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Publication numberUS3919885 A
Publication typeGrant
Publication dateNov 18, 1975
Filing dateJan 31, 1974
Priority dateMar 24, 1972
Publication numberUS 3919885 A, US 3919885A, US-A-3919885, US3919885 A, US3919885A
InventorsKaireit Manfred Gustav
Original AssigneeHarbeke Gerold J
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for dynamically analyzing an electronic fuel injection system and the associated engine parts
US 3919885 A
Abstract
Defect detecting apparatus for use with an internal combustion engine comprising means for sensing at least the speed, load condition, and ambient temperature of the internal combustion engine; fuel injection means injecting a variable amount of fuel into the cylinder of the engine in response to at least one control signal; control means for generating the control signal in response to the sensing means; and defect detecting means responsive to at least the sensing means, the fuel injection means, and the control means for dynamically detecting any defects within the sensing means, the fuel injection means, the control means, and the engine while the engine is running without interfering with the operation of the engine, the sensing means, the fuel injection means and the control means. Reference signal generating means may be substituted for the above control means to isolate the defect in either (1) the sensing means, the fuel injection means, or the engine or (2) the control means. Further, the signal generating means may be used as a control means to control the operation of the fuel injection system and run the engine.
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United States Patent Kaireit [451 Nov. 18, 1975 APPARATUS FOR DYNAMICALLY ANALYZING AN ELECTRONIC FUEL INJECTION SYSTEM AND THE ASSOCIATED ENGINE PARTS [75] Inventor: Manfred Gustav Kaireit, West Palm Beach, Fla.

[73] Assignee: Gerold J. Harbeke, Lake Worth,

Fla.

22 Filed: Jan. 31, 1974 21 Appl No.: 438,446

Related US. Application Data [63] Continuation of Ser. No. 237,828, March 24, i972.

abandoned.

[52] US. Cl 73/119 A [51] Int. Cl. G01M 15/00 [58] Field of Search 73/l 19 A, 1173, 118

[56] References Cited UNITED STATES PATENTS 3,463,130 8/l969 Reichardt et al. 73/l 19 A UX 3,732,492 5/1973 Geul 73/1 l9 A X Primary E.\'aminer.lerry H. Myracle [57] ABSTRACT Defect detecting apparatus for use with an internal combustion engine comprising means for sensing at least the speed, load condition, and ambient tempera ture of the internal combustion engine; fuel injection means injecting a variable amount of fuel into the cylinder of the engine in response to at least one control signal; control means for generating the control signal in response to the sensing means; and defect detecting means responsive to at least the sensing means, the fuel injection means, and the control means for dynamically detecting any defects within the sensing means, the fuel injection means, the control means, and the engine while the engine is running without interfering with the operation of the engine, the sensing means, the fuel injection means and the control means. Reference signal generating means may be substituted for the above control means to isolate the defect in either (1) the sensing means, the fuel injection means, or the engine or (2) the control means. Further, the signal generating means may be used as a control means to control the operation of the fuel injection system and run the engine.

46 Claims, 13 Drawing Figures comm/m0 FUEL SENSORS TL UNIT 52: INJECTOR I L- 2o 30; J 28 REFERENCE I ANALYZER GENERATOR I is L/m I L USE Pawn?! Nov. 12%, .975 5116i? 1 of6 3,919,885

10 I2 24 T6 2s COMMANO FUEL SENSORS UNIT }Z INJECTOR T T 22 I REFERENCE ANALYZER L OENERATOR I L/I4 I ELECTRIC F l G. [A FUEL TANK 53% V FUEL PUMP 74 75 (PRIOR ART) 78 80 79 F Aux. 46 AIR RUN/G MAlN/ AlR CLEANER THROTTLE SWITCH l 45 ,40

1 SENSOR T ENRi lEl ViENT '52 56 3 I2 MEANs U 66 44 COMMANO UNIT OR a B 60 T URE V REFERENCE sTANOARO 62 mm A US. Patent Nov. 18, 1975 Sheet 2 of6 3,919,885

FIG. 2

TRIGGER CONTACTS l NTAKE MANIFOLD 10; 132% 06 36 IL? 255;

M I I I Lain) i 1 x38 1 n2 pm I 3 [00 H4 254 TEMPERATURE F|G 4 SENSOR 42 COMMAND l I56 UNIT m 264 M5 FUEL INJECTOR I64 I60 '62 FIG 5 COIL @fi I66 I72 T0 LAMP 202 2 mflwl E I f FUEL PUMP m? I70 F|G.6 i:

APPARATUS FOR DYNAMICALLY ANALYZING AN ELECTRONIC FUEL INJECTION SYSTEM AND THE ASSOCIATED ENGINE PARTS This is a continuation of application Ser. No. 237,828, filed Mar. 24, 1972, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to apparatus for detecting defects within an electronic fuel injection system and, in particular, to apparatus of the above type where the defect detection occurs while the engine is running and without interfering with the operation of the engine and the fuel injection system.

2. Discussion of the Prior Art Electronic fuel injection systems are known and have been described in various US. Pat. such as Nos. 2,883,976 granted to S. G. Woodward et al.; 3,460,520 granted to R. Huber; and 3,463,130 granted to W. Reichardt et al. Further, patents have been granted on various systems for monitoring various aspects of internal combustion engines and the like such as US. Pat. Nos. 3,358,499 granted to G. Fourtane; 3,456,497 granted to E. Eberl; 3,512,405 granted to D. Schlicher; and 3,572.l03 granted to J. Marino.

However, heretofore, the apparatus utilized to monitor the performance of electronic fuel injection systems has essentially done so on a static basis.

SUMMARY OF THE INVENTION In contradistinction to the known static testing systems for electronic fuel injection systems, the system of this invention dynamically monitors the fuel injection system in such a way that there is no interference with the operation of the engine or the fuel injection system. Further, the operating parameters of the fuel injection system are so monitored that detected defects are substantially isolated in a particular portion of the system.

Thus, it is a primary object of this invention to provide apparatus for dynamically monitoring the performance of an electronic fuel injection system without interfering with the operation of the engine or the fuel injection system.

It is a further object of this invention to monitor the performance of the pressure sensor, temperature sensor, speed sensor, pressure switch, throttle switch, fuel pump, fuel injection valves, and command unit of a fuel injection system to detect either mechanical or electrical failures in the above elements or the engine such as vacuum losses.

It is a further object of the invention to provide a reference signal generator responsive to the sensors of the fuel injection system for isolating defects either in the ,bon waste, and prolongs the life of the fuel injection 'valve stem and seat.

Other objects and advantages of this invention will become apparent upon reading the appended claims in conjunction with the following detailed description and the attached drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram of an illustrative overall embodiment of the invention.

FIG. 1A is a schematic diagram of a fuel injection system which may be in accordance with the prior art.

FIG. 2 is a combined block and schematic diagram of an illustrative embodiment of the speed sensing circuitry of this invention together with circuitry for indicating the status thereof.

FIG. 3 is a combined block and schematic diagram of the load condition sensing means of this invention together with circuitry for indicating the status thereof.

FIG. 4 is a combined block and schematic diagram of the temperature sensing means of this invention together with circuitry for indicating the status thereof.

FIG. 5 is a combined block and schematic diagram of illustrative fuel injection means for use with this invention together with circuitry for indicating the status thereof.

FIG. 6 is a combined block and schematic diagram for circuitry for controlling a fuel pump in accordance with this invention.

FIG. 7 is a schematic diagram of the circuitry for detecting defects within a fuel injection system and associated parts of an internal combustion engine.

FIG. 7A is a plan view of an illustrative display panel in accordance with this invention.

' FIG. 8 is a combined block and schematic diagram of an illustrative embodiment of a reference signal generator in accordance with this invention.

FIGS. 9 and 10 are combined block and schematic diagrams of illustrative embodiments of details within the circuitry of FIG. 8.

FIGS. 11A through 11,] are waveforms illustrating the operation of the circuitry of FIGS. 8 through 10.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring to FIG. I there is shown an illustrative overall system block diagram of the invention. Sensors l0 sense load conditions, ambient temperatures. and speed of an internal combustion engine. Sensors I0 are connected to a command unit 12 or reference generator or reference standard or reference generating means 14 through a switch 16. The sensors 10 are also connected to analyzer or defect detecting means 18 over line 20. Reference generator 14 and analyzer 18 collectively comprise the dynamic fuel injection analyzer of this invention and are indicated within the dotted block 22. Command unit 12 is connected to fuel injectors 24 through switch 26 which is ganged with switch 16. Reference generator 14 is also connected to fuel injectors 24 depending on the setting of switch 16 over line 28. Either command unit 12 or reference generator 24 is connected to analyzer 18 over line 30, once again, depending on the setting of switches 16 and 26.

In operation, the system of FIG. 1 functions as follows. Normally the switches 16 and 26 are set in the upward position so that sensors 10 are connected to command unit 12 while unit 12 is connected to the fuel injectors 24. Hence, in this first mode of operation, reference generator 14 is not in the circuit. The analyzer 18 is responsive to the sensing signals generated by sensors 10 and the command or control signals generated by unit 12 to energize the fuel injectors 24. Hence, any defects in either the sensors 10, command unit 12, fuel injectors 24 or the engine can be detected and analyzed 3 by unit 18. In order to further isolate any defects detected by analyzer 18, the switches 16 and 26 are switched to the position shown in FIG. I. The sensing signals are then applied to reference generator 14, which, in response thereto, generate control signals for the fuel injector over line 28, these signals also being applied to analyzer 18 over line 30. Since it is known beforehand that the control signals produced by generator 14 are not defective, it can be assumed that the defect. if still detected by analyzer 18, is in the enginethat is. either in the sensors or the fuel injectors 24.

Referring now to FIG. 1A, there is shown an electric fuel injection system of the prior art. which illustrates in diagrammatic detail the various sensors incorporated within the block 10 of FIG. 1 together with an illustrative fuel injection device. The engine speed is detected by speed sensing means 32 connected to the engine distributor. which will be discussed in further detail hereinafter. The speed sensing means applies a speed sensing signal over line 34 to command unit 12, which, as indicated hereinbefore. may be replaced by reference generator 14. The load conditions of the motor are sensed by pressure sensing means 36, which measures the vacuum in the air intake manifold 38 and in response thereto applies a load condition sensing signal over line 40 to the command unit 12. The ambient temperature is measured by temperature sensing means 42 which generate a temperature sensing signal which is applied over line 44 to command unit 12. Sensing means 42 will be described in more detail hereinafter. The air is induced into manifold 38 through air cleaner 46 and throttle valve 48.

The position of throttle valve 48 is sensed by switch 50 to detect whether it is open or closed and the signal generated by this switch is applied to command unit 12 over line 52. A pressure switch 54 is also connected to the air intake manifold and measures the difference between the pressure therein and the outer atmosphere at full load to generate a pressure difference signal which is applied over line 56 to command unit 12.

The air drawn into manifold 38 is mixed with fuel injected by a fuel injector valve 58. This valve is associated with one of the cylinders in the car. Assuming a four cylinder car. the valves for the other cylinder are indicated at 60 through 64. Hence. valves 58 through 64 collectively correspond to the injectors indicated at 24 in FIG. 1. These valves are controlled by control signals applied over lines 66, 68, and 72 from command unit 12. It should be noted that in the prior art embodiment, a single control signal is applied to a pair of valves whereas in accordance with one aspect of this invention as will be brought out in more detail hereinafter, separate. individual control signals are respectively applied to each of the fuel injection valves regardless of the number of valves.

There is further shown in FIG. 1 a fuel tank 74 connected to fuel pump 76 through fuel filter 78. Fuel for each of the cylinders is distributed through ring main 79, there only being shown in FIG. 1A the connection to the first cylinder. A pressure regulator 80 maintains the pressure at a predetermined pressure such as 17 or 28 psi and enables excess fuel to be returned to the fuel tank 74. The fuel pump is controlled from command unit 12 over line 82.

Reference should now be made to FIG. 2 wherein there is shown in further detail the relationship between the command unit 12 or reference generator 14 and the speed sensing means 32 together with means 4 for detecting defects either in the unit 12 or the sensor 32, the defect detecting means being generally indicated at 84. The speed sensor means is part of the prior art and comprises first and second pairs of contacts 86 and 88, which are alternatively opened and closed by cam means mounted in the lower section of the ignition distributor. The first defect detecting means 84 comprises a resistor and a first status indicating means 92, which is also indicated as M9. Status indicating means 92 is preferably a modified ammeter which is responsive to the average value of alternative dc pulses applied thereto as will be brought out in more detail hereinafter. The first status indicating means also includes a second resistor 96 and a meter 98, which are prespectively identical to resistor 90 and meter 92. Meters 92 and 98 are respectively associated with trigger contacts 88 and 86. The description hereinafter will be mainly directed to meter 92 inasmuch as meter 98 is the same as meter 92. In operation, the command unit 12 applies over line 94 a first interrogation signal which typically is a dc voltage to the contact pair 88. As contact pair 88 is successively opened and closed, a direct current pulse train will be applied over line 94 to command unit 12, which. in response thereto, will generate control signals for the actuation of the fuel injectors. As will be brought out in detail hereinafter, other sensing signals are also utilized to develop the control signals applied to the fuel injectors.

Assuming no defect is in the speed sensing system or in the engine. a small amount of the pulse trains applied from contacts 88 will also be applied to meter 92, the resistance 90 being so chosen that the defect detecting circuit 84 does not interfere with the normal operation of the speed sensing means. In other words, the resistance 90 is of a sufficiently high magnitude to prevent undesirable loading of the speed sensing circuitry by the defect detecting circuitry. The signal applied to meter 92 during normal operation causes the needle of the meter to be at substantially center scale at a predetermined engine speed. Typically, this speed might be 500 rpm. Thus, the meter 92 may be calibrated to provide a center scale reading for an engine speed of 500 rpm.

Several of the possible defects which can occur in the speed sensing means 32 or the command unit 12 will now be discussed. First, if either of the contacts of contact pair 88 has been burned'thereby forming corrosion, there will be an imbalance in the magnitude of the signals applied to command unit 12. Inasmuch as meter 92 reads the average dc value of the signal occurring on line 94, a deflection either right or left of center on the scale of meter 92 will occur if the contact pair 88 has become defective.

If an open circuit occurs in the line including contact pair 88, this will be detected immediately when the ignition switch is turned on inasmuch as the interrogation signal will be applied over line 94 and only through meter 92 to effect full scale deflection thereof. Further, if a short circuit or leakage from one cable to the line including contact pair 88 occurs, the interrogation signal will be shorted to ground thereby effecting little if any deflection of the meter 92. Further, the interrogation signal applied over line 94 may be defective, which will also be indicated on meter 92.

Hence, if defects are detected on meters 92 or 98, it can be immediately established that the defect is either in the speed sensor 32 or in the command unit 12. As described hereinbefore, the command unit 12 can be switched out by switches 16 and 26 of FIG. 1 and replaced by reference generator 14. If the meters 92 or 98 still indicate a defect, then the defect has been isolated in the speed sensor 32. However, if the indicators 92 or 98 indicate no defect, then the defect has been isolated in the interrogation signals applied over lines 94 or 95.

Referring now to FIG. 3 there is shown a pressure sensor 36 corresponding to that shown in FIG. 1. The pressure sensor 36 includes a substantially air tight cylinder 100 which may include a diaphragm 102 disposed in air tight relationship therein. The diaphragm 102 divides the cylinder 100 into two chambers 104 and 106. Chamber 104 is connected to air intake manifold 38 by an appropriate coupling or line 108. The diaphragm 102 is connected to core by rod 112. The core 110 is typically made of magnetic material and disposed between a primary winding 114 and a secondary winding 116 of a transformer 118. The command unit 12 or ref erence signal generator 14 applies an alternating current or pulses or second interrogation signal to primary winding 114 which are coupled to secondary winding 116 and then returned to the command unit 12. The signal sensed across winding 116 has a parameter which is a function of the vacuum measured in intake manifold 38.

The foregoing is part of the prior art, however, a brief description of the pressure sensor will be given to facilitate understanding of the instant invention and its efficacy in detecting defects in the pressure sensor and manifold. A second interrogation signal is applied to the primary winding which tends to attract core 110 in the direction of the arrow A. However, this tendency is counteracted by the vacuum present in the manifold 38 which tends to attract the diaphragm 102 in the direction of the arrow B. Since the diaphragm and core are connected by rod 112, the diaphragm 102 stays in an equilibrium position as long as the pressure or vacuum in manifold 38 remains constant. Referring to FIG. 1A, if throttle valve 48 is opened, thereby causing the pressure in manifold 38 to decrease, there will be a tendency for the diaphragm 102 to move in the direction of the arrow B. This will move the core 110 thereby changing the load sensing signal applied across secondary winding 116. This change in the load condition is sensed by command unit 12 and utilized in the development of the control signals which are applied to the fuel injectors, which will be described in more detail hereinafter.

In order to detect any defects in command unit 12, pressure sensor 36 or manifold 38, second defect detecting means 120 are utilized in accordance with this invention. Second defect detecting means 120 com prises first and second Wheatstone bridges 122 and 124. The components comprising Wheatstone bridges are of the same type but may be of different values. Hence. the following discussion will be mainly directed to Wheatstone bridge 122 will be briefly discussed. Wheatstone bridge 124 is connected across primary winding 114 and includes signal diodes 126 and 128, second status indicating means or modified ammeter 130, and resistors 132 and 134. Meter 130 reads aven age current applied thereto and resistors 132 and 134 are so selected to correspond to a predetermined load condition in manifold 38 which is a function of the particular kind of automobile with which the second defect detecting means is used. Typical values for these 6 resistors are given in FIG. 7 which will be discussed in more detail hereinafter.

The Wheatstone bridge 122 comprises diodes 136 and 138, meter 140 which is also included within the second status indicating means, and resistors 142 and 144.

Assuming normal operation of the pressure sensor, intake manifold, and command unit, the null-detection meters 130 and 140 will be positioned at substantially center scale for a predetermined load condition. If a leak occurs in diaphragm 102 the diaphragm will move in the direction of the arrow B toward the extreme left of cylinder 102. This will unbalance the signals occurring at diodes 126 and 128 such that the meter 130 will indicate a full scale reading and thereby indicate the diaphragm leak.

A further defect which may occur is a leak in the manifold 38 or coupling 108 thereby causing a vacuum loss. This causes the diaphragm 102 to be pushed to the right of cylinder 100--once again, unbalancing the signals occurring across and reflected back into primary winding 114 so that the meter 130 is deflected in the direction opposite from that for a diaphragm leak. That is, the needle will be deflected in one direction for a vacuum leak and in the other direction for a diaphragm leak. Further, an open circuit in the primary winding 114 is also indicated on meter 130 by a deflection in the same direction as occurs for a vacuum leak. An open circuit in secondary winding 116 is indicated on meter 140 in thesame manner as an open circuit is indicated on meter 130.

From the foregoing it can be seen that meters 130 and 140 can detect defects either in the intake manifold 38, the pressure sensor 36 or the command unit 12. As discussed hereinbefore, the command unit 12 can be replaced by the reference generator 14 to isolate the defect either in the command unit or in the engine including the intake manifold 38 or the pressure sensor 36.

Referring to FIG. 4 there is shown the temperature sensing means or sensor 42 which typically comprises a thermister 146, the resistance of which is an inverse function of the sensed temperature. As will be brought out in more detail hereinafter, at least two temperature sensors are used in this invention and are typically placed in the air intake manifold, the cylinder head. or the crank case. These sensors measure ambient engine temperature and generate temperature sensing signals which are applied to command unit 12 in response to a third interrogation signal applied thereto over line 148. The signal applied from the command unit is typically a dc voltage and the sensing signal generated by sensor 42 results from the fact that the resistance of the thermister varies with temperature. A third defect detecting means is connected across temperature sensor 42 and comprises resistor 152 and third status indicating means or meter 154. Meter 154 is typically a direct current micro-ammeter and is calibrated so that as long as the sensed temperature is normal, a center scale reading is provided. However, if overheating occurs in any of the engine parts sensed by the temperature sensors, the current through meter 154 will decrease because of the decrease in resistance of the thermister 146. A short circuit would also cause a deflection in meter 154 corresponding to that of overheating. An open circuit in the line including thermister 146 will cause a full scale reading of the meter 154. However. since, when the engine is cold, the resistance of thermister 146 will be high and thereby also cause a full scale reading of meter 154, the meter 154 will not reliably indicate an open circuit until the engine has reached its normal operating temperature.

Defects in the command unit 12 causing a defective interrogation signal on line 148 are also detected by meter 154. Hence, as described hereinbefore. the command unit 12 may be replaced with the reference generator 14 to isolate the location of the defect.

Referring to FIG. 5, there is shown the energization coil 156 of a fuel injector such as shown at 58 in FIG. 1A. The fuel injector is magnetically operated and opens and closes depending on whether an energization, control signal or pulse is applied to coil 156. A fourth status indicating circuit 158 comprising resistor 160 and fourth status indicating means or meter 162 is connected across the fuel injector coil 156 and is responsive to the control signals applied from command unit 12 or reference signal generator 14. An illustrative value of resistor 160 is given in FIG. 7 as is the case for the other resistors used in the status indicating circuits of this invention. Those values are given for illustrative purposes only. Meter 162 is the same type of meter as meters 92 and 98 described in connection with FIG. 2. Meter 162 is so calibrated that the center reading thereof corresponds to a predetermined engine speed, load condition, and ambient temperature. An open circuit in the line including fuel injector coil 156 causes a full scale deflection of meter 162. Loose or corroded grounds will also cause deflection of meter 162 in the direction of a full scale reading. The deflection will typically not be as great with a corroded ground and thus, the amount of the deflection of the meter also tends to isolate the particular kind of defect involved. A short circuit or leakage in the line including coil 156 causes little if any deflection of the meter 162. Thus. defect detecting means 158 is responsive to the control signals generated by command unit 12 or reference signal gen erator 14 to detect defects either in the command unit or the fuel injector system.

A further defect which can occur in the fuel injection system is internal corrosion of the fuel injection nozzle.-

Means for detecting this are indicated at 164 which comprises a voltage source 166 and momentary contact switch 168. By depressing switch 168 a momentary contact is established which causes a pulse to be applied to the fuel injector coil 156. This pulse should then cause fuel to be injected by the injector. Hence, if nozzle corrosion is present. this will be detected by the failure of the valve to inject the fuel which can be readily observed.

In first, second, third, and fourth status indicating means described hereinbefore, the loading of these means on the operating sensors, command unit and fuel injection devices is negligible. Further, in all of these status indicating devices, a defect in either the sensors, command unit or fuel injection devices is detected. Thus. for example, if a short occurs in the output circuitry of the command unit, which generates the control signals for the injectors, this also will be detected by meter 162 whereby the short can be isolated in the command unit by replacing it with the reference signal generator. After such a replacement, the status indicated by meter 162 will be normal and thus the short will have been isolated in the command unit.

Reference should now be made to FIG. 6 which illustrates circuitry for energizing the fuel pump 76 for a predetermined amount of time to bring the pressure in 8 the fuel line up to rated pressure which may typically be 17 or 28 psi. The command unit 12 generates a pulse of predetermined length to energize relay 170 and close contact 172 thereby connecting the pump to a source of dc voltage for the predetermined length of time to thereby bring the pump up to rated pressure.

Reference should now be made to FIG. 7 which is a schematic diagram of the analyzer or defect detecting means 18 of FIG. 1. The circuitry of FIG. 7 includes a B line 174 and a ground line 176. A meter 178 or M1 is connected across lines 174 and 176 and indicates that the ignition key has been turned on and that defect detector 18 has received its operating voltage. The engine is then turned on and the various elements of the fuel injection system are monitored as follows.

When the engine is started, the command unit 12 is responsive to the starting solenoid or fuel enrichment means 45 of FIG. 1A to generate a fuel enrichment signal which is applied to the fuel injectors. The presence of the fuel enrichment signal is detected at terminal 180 and amplified in amplifier 182 and applied to switch 184 to energize light 186 or L2.

As will be brought out in more detail hereinafter, the defect detecting circuitry 18 of FIG. 7 analyzes fuel injection systems of differing types. Thus, two types which are presently commercially available are the socalled type III and type IV systems. However, it is to be understood that the defect detector 18 of the subject invention can be used with and adapted to any type of electronically controlled fuel injection system. Hence, switch 188 or S2 is utilized to switch the analyzer to either the type III or type IV mode of operation. Switch S2 is ganged to switches 189, 190, 191, 192, 194, 196, and 198. The switches are shown in the type III mode position.

Terminal 200 is connected to command unit 12 as indicated in FIG. 6 to energize lamp 202 or L1 to thereby indicate proper operation of the fuel pump relay 76 and the associated power input circuitry from the command unit 12. The signal generated by command unit 12 is applied to amplifier 204 and thence to switch 206 where lamp 202 is energized.

Terminal 208 is connected to line 52 which is connected to the throttle valve switch 54 of FIG. 1A. The throttle valve switch controls the cutoff of fuel at typically 1800 rpm and the supply of fuel when coating at typically 1250 rpm. The proper operation of switch 54 is detected by a signal applied to terminal 208 from the switch when the throttle valve is closed during idle, this signal being applied through switch 192 and amplifier 210 to switch 212 to energize fifth status indicating means or lamp 214 or L6. Defective operation of the throttle valve can thus be detected if, after depressing the accelerator, the lamp 214 continues to light. That is, the throttle valve should open upon depression of the accelerator peddle thereby deenergizing lamp 214 and thus, a faulty throttle valve can be detected.

Defective components within the command unit 12 can also be sensed at lamp 214 since terminal 216 is connected thereto through amplifiers 218, 220, and 222 and switch 212. Terminal 216 is connected to a floating ground in the command unit 12 to which all circuits are referred. Thus, breakdown of any compo nents in the command unit is sensed at terminal 216.

Thus, in summary, with respect to lamp 214- or L6, this lamp should be on when the throttle valve is closed and off when the throttle valve opened in response to the depression of the accelerator. However, if the lamp remains on, this indicates either a faulty component within the command unit via terminal 216 or a faulty throttle valve or a vacuum leak via terminal 208.

Lamp 224 or L serves a function similar to lamp 214 except that lamp 224 is associated with type IV systems and is connected to terminal 208 through switch 192 (which would be in its lower position), amplifier 226 and switch 228. Terminal 216 may also be connected to lamp L5 in a manner similar to the way in which it is connected to lamp 214, however, for purposes of clarity it is not indicated in FIG. 7.

Sixth status indicating means or lamp 230 or L7 is connected to terminal 232 which in turn is connected to line 56 connected to pressure switch 54 of FIG. 1A. The pressure switch generates a pulse of predetermined width when the accelerator is so depressed as to place the engine under full load condition such as a rapid start from standstill. The pressure on the high vacuum side of the throttle valve is then drastically reduced thereby causing pressure switch 54 to generate the above mentioned pulse and apply it to terminal 232 through switching contacts 190, amplifier 234, and switch 236 to energize lamp 230. Hence, if lamp 230 comes on when the accelerator is rapidly depressed, the pressure switch is operating satisfactorily. However, if it does not come on either the pressure switch is faulty or a vacuum leak has occurred in the high vacuum side of the vacuum system. The throttle valve switch, discussed hereinbefore, is employed via lamps 224 or 214 to detect vacuum leaks in the low vacuum end of the vacuum system. The throttle valve 48 divides the high vacuum end which is to the right in FIG. 1A from the low vacuum end of the system.

Referring again to terminal 232, when the system is in the type IV mode of operation, the switch contact 190 will be in downward position. However, in the type IV mode of operation the signal generated by pressure switch 54 is termed an acceleration enrichment signa Nevertheless, this signal is equivalent to the signal applied to lamp 230 or L7 in that it indicates that a full load condition has been sensed by the pressure switch. The acceleration enrichment signal is applied through the downwardly disposed contact 190 through amplifier 238 and switch 240 to lamp 242 or L3. Thus, L3 detects essentially the same conditions as detected by L7 or 230, as described above. Lamp 244 or L4 is connected to terminal 216 through switching contacts 189, amplifier 246 and switch 248. In the type IV embodiment additional information regarding the acceleration enrichment is provided to terminal 216 and the presence of this information is indicated at lamp 244 or L4. However, if the pressure sensor is faulty, this acceleration enrichment signal may not be applied to terminal 216 under full load conditions and thus, lamp 244 would not be energized indicating a fault condition.

The status indicating means for the speed, load condition, and ambient temperature sensing means and fuel injection means described hereinbefore with respect to FIGS. 3 through 6 are also shown in FIG. 7. Thus, terminals 250, 252, 254, 256, 258, 260 and 264 are shown in FIGS. 2-5 and 7. Terminal 262 is con- ;nected to the second temperature sensing means mentioned hereinbefore in connection with the description of the temperature sensing circuitry of FIG. 4. Terminals 264 through 270 are respectively connected to the drive circuits for the four cylinders of the automobile, it of course being realized that the number of such circuits could be expanded depending upon the number of cylinders. Terminals 272, 274 and 276 are special input terminals used for type IV injection systems and do not form a part of this invention. Switch *278 or S1 when closed connects all lamps of the circuitry of FIG. 7 to B to assure that the lamps have not burned out and also for reference purposes.

Referring now to FIG. 7A there is illustrated a typical display panel for illustrating the conditions described hereinbefore and detected by the circuitry of FIG. 7. Thus, on FIG. 7A the reference numerals correspond to the corresponding meters or lamps already described with respect to FIG. 7. There is further shown on the display panel of FIG. 7A a pump test switch which is utilized with the test described hereinbefore with respect to circuit 164 of FIG. 5. The purpose of the pump test switch is to actuate means not shown to lower the fuel pressure to a certain level and then bring it back up again to the required level to conduct the test described hereinbefore with respect to circuitry 164. The pump test switch is indicated at 280. The fuel pressure is indicated at gauge 282.

Reference should now be made to FIGS. 8-11 wherein it is described circuitry corresponding to an illustrative embodiment of the reference generator 14 of FIG. 1. The reference generator may have as its power source an automobile battery 284, the output voltage of which is regulated by voltage regulator 286. The dc output voltage from the voltage regulator is applied to an oscillator 288 which generates the signal which is applied to the primary winding 114 of FIG. 3, which is included in the pressure sensor 32. The output of the pressure sensor is applied to an AC to DC converter 34, the output of which is representative of the sensed load condition in the air intake manifold, as discussed in detail hereinbefore. The output signal from converter 290 is applied to a summing network 292 comprising resistors 294-298. Also applied to the summing network may be a dc signal from a sensor 300 for sensing the height of the engine above sea level. Such sensors are well known and generally are responsive to barometric pressure with respect to a predetermined level such as sealevel. The use of the height sensing signal permits optimization of the fuel/air ratio. Also applied to summing network 292 is a temperature signal derived from temperature sensors such as that described in FIG. 4. Thus, the temperature sensed in the cylinder head is applied as a dc voltage to resistor 302 while the temperature from the crank case or air intake manifold is applied to resistor 304. These resistors are connected to a noninverting input of a differential type operational amplifier 306. An inverting input of the amplifier is connected to a reference signal established at potentiometer 308. The above type amplifier is well known to those of ordinary skill in this art and generally discussed in Electronics Engineers Handbook, Landee, Davis, and Albrecht, I957, pp. l9-6 through 19-1 1. The potentiometer 308 is so set that the voltage therefrom corresponds to a predetermined normal operating temperature for the particular automobile being tested or operated. The operational amplifier 306 produces a reference voltage when the sensing signal applied from the temperature sensors through resistors 302 (which is connected at its other end to terminal 260 of FIG. 4) and 304 equals in absolute magnitude that produced by reference potentiometer 308. However, any deviation in the sensed temperature from the reference temperature will produce a change in the output voltage level from amplifier 306 which is applied to the summing network 302 and thence to another differential type operational amplifier 310, the operation of which is the same as that of amplifier 306. To the inverting input of the amplifier 310 is applied a reference voltage, once again dependent on the type of engine which corresponds to a predetermined, combined load condition and temperature signal for the selected type of automobile. The reference voltage is selected by switch 312 from one of the voltage divider networks 314 through 320. Any deviation of the signal applied from summing network 392 from the selected reference voltage will cause a change in the output voltage level from amplifier 310 on line 311. This change in output voltage is applied to a voltage controlled timing circuit 312, which will be described in more detail hereinafter in FIG. 9. Timing circuit 312 is also responsive to a timing signal applied over line 313 from valve selection logic circuit 314 over line 316, which will be described in more detail hereinafter with respect to FIG. 10. Logic circuitry 314 is responsive to distributor contacts 86 and 88 in speed sensor 32 to develop the control pulses applied to fuel injectors 58 through 64.

Referring to FIG. 9 there is shown in more detail the circuitry of voltage controlled timing circuit 312. This circuitry comprises a flip-flop 318 having its SET input connected to line 316 from valve selection logic 314 of FIG. 8. The SET output of flip-flop 318 is connected to an integrating circuit comprising resistor 320 and capacitor 322. The output of the integrator is applied to a voltage comparator circuit 324 such as described in Pulse and Digital Circuits" by Millman and Taub. McGraw Hill Book Company. Inc., 1956. pages 458484. The reference signal for the voltage comparator 324 is connected over line 311 from operational amplifier 310. The output from voltage comparator 324 is applied over line 326 to the RESET input of flip flop 218.

Reference should now be made to FIG. 11 for a description of the operation of FIG. 9. In FIGS. 11A and 11B there is shown the signals generated by contacts 86 and 88 and applied to lines 95 and 94 of FIGS. 2 and 8. As will be brought out in more detail hereinafter means within the valve selection logic circuitry 314 generates the trigger pulses shown in FIG. 11C at each transition of the speed sensing signals generated on lines 94 and 95. These trigger signals occur every 90 and are applied to the SET input of flip-flop 318 of FIG. 9 to set the flip-flop and initiate charging of condenser 322. The setting of flip-flop 318 also causes a voltage pulse to be initiated on line 313 which is applied to the valve selection logic 314 of FIG. 8. Assuming that the first solenoid is to be driven, a first pulse is applied from the output of valve selection logic 314 to the circuitry for driving the solenoid of fuel injection valve 58. This pulse is shown in FIG. 11F and the leading edge thereof corresponds to the setting of flip-flop 318.

The setting of flip-flop 318 will also initiate charging of capacitor 322 which charges up to the reference voltage value occurring on line 311. The operation of the comparator 324 is such that when the voltage level on each of the input lines thereto is equal, a pulse is generated which resets flip-flop 318. The resetting of flip-flop 318 corresponds to the trailing edge of the control pulse or signal applied to fuel injector 58 and shown in FIG. 11F. Capacitor 322 starts to discharge when flip-flop 318 is reset. It will continue to discharge until flip-flop 318 is again set by the next trigger pulse. Since the spacing between the pulses isa function of the sensed engine speed, the amount that capacitor 322 discharges will vary according to engine speed and thus, the length of time it takes for the capacitor to recharge to the reference voltage will also vary according to engine speed. Since the reference voltage also varies according to pressure and temperature, the length of the pulse generated by flip-flop 318 varies according to pressure, temperature, and speed.

Reference should now be made to FIG. 10 which illustrates an illustrative embodiment of the valve selection logic circuitry 314 of FIG. 8. The speed sensors 86 and 88 are respectively connected over lines 95 and 94 to generate the signals shown in FIGS. 11A and 11B and, lines 94 and95 being respectively labelled A and B. Invertors 326 and 328 respectively provide A and B signals. These invertors may each comprise a single stage NPN transistor circuit (not shown) with the collector connected to line 301 through a load resistor, the base connected through a biasing resistor to line 301, and the emitter connected to ground.

The AA, B, and B signals are combined in different combinations in AND circuits 330, 332, 334 and 336 which respectively generate AB, AB, AB, and AB functions which are applied to OR circuit 338. The leading edge of each of these functions is differentiated by a differentiator indicated at 340 to provide the trigger pulses shown in FIG. 11C of the drawing. The A, A, B, and B signals are also applied to AND circuits 342, 344, 346 and 348 in the combinations indicated in FIG. 10. Further, to each of these AND circuits is also applied the SET output of flip-flop 318 of FIG. 9 over line 313. Thus, depending on which of the A or B functions is occurring at a particular time one of the AND circuits 342 through 348 will be selected thereby effecting distribution of the control pulses to the solenoid drivers for the fuel injectors 58 through 64.

In FIG. 10 the solenoid for fuel injector 58 is indicated at 156 and corresponds to that also shown in FIG. 5. The driving circuit comprises a transistor 358 having an integrating or pulse forming circuit 360 connected to the base thereof. The integrating or pulse forming circuit 360 comprises resistor 362 and capacitor 364 and operates on the input pulse applied thereto as shown in FIG. 11F to shape the pulse to produce the pulse shown in FIG. 11G. Typically, the length of the pulse shown in FIG. 11F will vary depending on the reference voltage applied to line 311 from the temperature and pressure sensors. It will also vary as a function of the speed sensed by sensors 32. The pulse width variation is typically 8 to 12 milliseconds and may vary depending on the type of engine. The RC time constant of pulse shaping circuit 160 is such that the rise time is typically 3 milliseconds and may vary over a range of 2.5 to 3.5 milliseconds for certain types of engines.

The purpose of decreasing the rise time is to minimize the impact of the control pulse on the fuel injection solenoid. That is, rather than slamming the fuel injector on with a pulse having a substantially vertical leading edge, the solenoid is gently turning on thereby prolonging valve stem and valve seat life. Further, the engine operation is also smoothed out.

Further, by applying four separate pulses respectively to the injectors 58 through 64 as is done in the reference generator of FIGS. 8 through 11, more accurate timing of the injection of the fuel into the cylinders in relation to piston position can be obtained. Hence, this 13 also results in smoother operation and more complete fuel combustion to lessen exhaust pollution such as by drocarbon waste.

From the foregoing description of the operation of the reference standard, it should be understood that it may be used not only as a reference standard in a dynamic fuel injection analyzing system as described hereinbefore; but it may also be used as a command unit 12 shown in FIG. 1 to operate and control the fuel injection system.

The line 301 is connected from the positive side of the voltage regulator and is utilized to provide either directly or indirectly the bias voltages for all of the blocks of FIG. 8. However, lines are shown connected only to blocks 306 and 316. The bias voltage applied to the input transistor (not shown) of controller 306 con nected to resistors 302 and 304 is the beforementioned third interrogation signal while the bias voltage applied to the base of the transistor invertors 326 and 328 of FIG. is the beforementioned first interrogation signal.

Numerous modifications of the invention will become apparent to one of ordinary skill in the art upon reading the foregoing disclosure. During such a reading it will be evident that this invention provides a unique dynamic fuel injection analyzing system for accomplishing the objects and advantages herein stated.

What is claimed is:

l. Defect detecting apparatus for use with an internal combustion engine comprising means for sensing at least the speed, load condition,

and ambient temperatures of said internal combustion engine;

fuel injection means for injecting a variable amount of fuel into the cylinder of said engine in response to at least one control signal;

control means for generating said control signal in response to said sensing means; and

defect detecting means responsive to said sensing means, said fuel injection means, and said control means for dynamically detecting predetermined defects within said sensing means, said fuel injection means, and said control means while said engine is running without interfering with the operation of said internal combustion engine, said sens ing means, said fuel injection means and said control means, said defect detecting means including status indicating means responsive to said control signal applied to said fuel injection means for indicating the status of said fuel injection means or said control means, said status indicating means, in response to said control signal, indicating the presence of an open circuit or very high resistance in said fuel injection means and said status indicating means, in response to the absence of said control signal, indicating either the presence of a short circuit or very low resistance in said fuel injection means or a defect in said control means.

2. Apparatus as in claim 1 where said sensing means includes speed sensing means for generating a first sensing signal, the frequency of which is a function of said engine speed and where said defect detecting means includes first status indicating means responsive to said first sensing signal for indicating the status of said speed sensing means.

3. Apparatus as in claim 2 where said sensing means includes load condition sensing means for generating a second sensing signal, a parameter of which is a func- 14 tion of the load condition of said engine and where said defect detecting means includes second status indicating means responsive to said second sensing signal for indicating the status of said load condition sensing means.

4. Apparatus as in claim 3 where said sensing means includes temperature sensing means for generating a third sensing signal, the magnitude of which is a function of said ambient temperature and where said defect detecting means includes third status indicating means responsive to said third sensing signal for indicating the status of said temperature sensing means.

5. Apparatus as in claim 1 where said sensing means includes speed sensing means for generating a first sensing signal representative of the speed of said engine in response to a first interrogation signal applied thereto from said control means and where said defect detecting means includes first status indicating means responsive to said first sensing signal and said first interrogation signal for indicating the status of said speed sensing means or said control means.

6. Apparatus as in claim 5 where said speed sensing means includes means responsive to the rotation of the ignition distributor for generating said first sensing signal, the frequency of which is a function of said engine speed and where said first status indicating means includes means responsive to said first sensing signal for indicating the desired presence thereof whereby said first status indicating means, in response to said first interrogation signal, indicates the presence of an open circuit or very high resistance in said speed sensing means and said first status indicating means, in response to the absence of said first interrogation signal, indicates the presence of a short circuit or very low resistance in said speed sensing means.

7. Apparatus as in claim 6 where said means respon' sive to the rotation of the ignition distributor includes at least one pair of contacts successively opened and closed in response to said rotation to generate said first sensing signal and where the said very high resistance condition indicated by said first status detecting means is corrosion of said contact pair.

8. Apparatus as in claim 5 where said sensing means includes load condition sensing means for generating a second sensing signal representative of the load condition of said engine in response to a second interrogation signal applied thereto from said control means and where said defect detecting means includes second status indicating means responsive to said second sensing signal and said second interrogation signal for indicating the status of said load condition sensing means or said control means.

9. Apparatus as in claim 8 where said load condition sensing means includes pressure measuring means located in the intake air distributor of said engine for generating said second sensing signal, a parameter of which is a function of the pressure, and where said second status indicating means includes means responsive to said second interrogation signal and said second sensing signal for indicating the desired presence thereof.

10. Apparatus as in claim 9 where said pressure measuring means includes l a transformer, to the primary winding of which is applied a second command signal and from the secondary winding of which is connected said second sensing signal to said control means, (2) an armature disposed between said primary and secondary windings and connected to a diaphragm slidably mounted in a substantially air-tight cylinder to divide said cylinder into at least two chambers, and (3) means for connecting said intake air distributor to one of said chambers and where said second status indicating means includes null-detecting means connected across said primary winding for indicating the status of said pressure measuring means whereby leakage in said diaphragm causes said nulldetecting means to move in a first direction and a vacuum leak or open primary circuit causes said null detector to move in a second direction.

11. Apparatus as in claim 10 where said second status indicating means includes null-detecting means connected across said secondary winding for detecting an open circuit in said secondary winding.

12. Apparatus as in claim 8 where said sensing means includes temperature sensing means for generating a third sensing signal representative of said ambient temperature in response to a third interrogation signal applied thereto from said control means and where said defect detecting means includes third status indicating means responsive to said third sensing signal and said third interrogation signal for indicating the status of said temperature sensing means or said control means.

13. Apparatus as in claim 12 where said temperature sensing means includes temperature-sensitive, resistive means located in the crank case and cylinder head of said engine for generating said third sensing signal, the magnitude of which is a function of said ambient temperature and where said third status indicating means includes means responsive to said third sensing signal for indicating the desired presence thereof whereby said third status indicating means, in response to said third interrogation signal, indicates the presence of an open circuit or very high resistance in said temperature sensing means and said third status indicating means, in response to the absence of said third interrogation signal, indicates the presence of a short circuit or very low resistance in said temperature sensing circuit.

14. Apparatus as in claim 1 where said control signal generated by said control means is a pre-established, reference control signal for isolating any defects indicated by said fourth status indicating means in said fuel injection means.

15. Apparatus as in claim 14 where said control means includes means for generating said reference control signal, said reference control signal generating means including means for generating a plurality of control signals respectively applied to a plurality of said fuel injection means whereby complete combustion in each of the plurality of cylinders connected to said fuel injection means is enhanced so that exhaust pollution is lowered.

16. Apparatus as in claim 14 where said control means includes means for generating said reference control signal, said reference control signal generating means including means for shaping said reference control signal so that the leading edge thereof is gradually sloped whereby the life of the valve stem and seat of said fuel injection means is prolonged.

17. Apparatus as in claim 14 where said control means includes means for sensing the height of said engine'with respect to a predetermined altitude for generating a height signal and means responsive to the height signal and said sensing signals for generating said control signal.

16 18. Apparatus as in claim 1 where said sensing means includes means responsive to the position of a throttle valve in the air intake manifold for generating a throttle valve sensing signal and where said defect detecting means includes fifth status indicating means for indicating the status of said throttle valve.

19. Apparatus as in claim 18 where said fifth status indicating means is a first lamp whereby a vacuum leak in the low vacuum end of said air intake manifold is detected by rapid, irregular flickering of said first lamp.

20. Apparatus as in claim 1 where said sensing means includes second pressure sensing means responsive to full load vacuum in the air intake manifold for generating a full load vacuum sensing signal and where said defect detecting means includes sixth status indicating means for indicating the status of said second pressure sensing means.

21. Apparatus as in claim 20 where said sixth status indicating means is a second lamp whereby said second lamp indicates a vacuum leak in the high vacuum end of said air intake manifold, if present.

22. Apparatus as in claim 1 where said sensing means includes means connected to a floating ground within said control means for generating a circuit imbalance signal whenever components within said control means are defective and where said defect detecting means includes seventh status indicating means for indicating the status of said components within said control means.

23. Apparatus as in claim 22 where said fifth and seventh sensing means are included in a common status indicating means, the fifth status indicating means being operative when the throttle valve is closed and the seventh status indicating means being operative when the throttle valve is opened.

24. Defect detecting apparatus for use with an internal combustion engine comprising means for sensing at least the speed, load condition,

and ambient temperatures of said internal combustion engine; 1

fuel injection means for injecting a variable amoun of fuel into the cylinder of said engine in response to at least one control signal; control means having at least one input terminal and at least one output terminal for generating said control signal in response to said sensing means;

reference signal generator means having at least one input terminal and at least one output terminal for generating a reference control signal in response to said sensing means;

switching means for respectively connecting said sensing means and said fuel injection means to said input and output terminals of said control means in a first position of said switching means and for respectively connecting said sensing means and fuel injection means to said input and output terminals of said reference signal generator means in a second position of said switching means; and

defect detecting means connected to said sensing means and said fuel injection means, said defect detecting means being further connected to the input and output terminals of said control means when said switching means is in said first position for dynamically detecting any defects within said sensing means, said fuel injection means, and said control means while said engine is running without interfering with the operation of said internal combustion engine, said sensing means, said fuel injection means and said control means. said defect detecting means being connected to the input and output terminals of said reference signal generator when said switching means is in said second position for dynamically isolating any detected defect to either said sensing means and said fuel injection means or said control means while said engine is running.

25. Apparatus as in claim 24 where said sensing means includes speed sensing means for generating a first sensing signal, the frequency of which is a function of said engine speed and where said defect detecting means includes first status indicating means responsive to said first sensing signal for indicating the status of said speed sensing means.

26. Apparatus as in claim 25 where said sensing means includes load condition sensing means for generating a second sensing signal, a parameter of which is a function of the load condition of said engine and where said defect detecting means includes second status indicating means responsive to said second sensing signal for indicating the status of said load condition sensing means.

27. Apparatus as in claim 26 where said sensing means includes temperature sensing for generating a third sensing signal, the magnitude of which is a function of said ambient temperature and where said defect detecting means includes third status indicating means responsive to said third sensing signal for indicating the status of said temperature sensing means.

28. Apparatus as in claim 27 where said control means includes means for generating a second interrogation signal and where said sensing means includes load condition sensing means for generating a second sensing signal representative of the load condition of said engine in response to said second interrogation signal applied thereto from said control means and where said defect detecting means includes second status indicating means responsive to said second sensing signal and said second interrogation signal for indicating the status of said load condition sensing means or said control means.

29. Apparatus as in claim 28 where said load condition sensing means includes pressure measuring means located in the intake air distributor of said engine for generating said second sensing signal, a parameter of which is a function of the pressure, and where said second status indicating means includes means responsive to said second interrogation signal and said second sensing signal for indicating the desired presence thereof.

30. Apparatus as in claim 29 where said pressure measuring means includes l a transformer, to the primary windin g of which is applied said second command signal and from the secondary winding of which is connected said second sensing signal to said control means, (2) an armature disposed between said primary and secondary windings and connected to a diaphragm slidably mounted in a substantially air-tight cylinder to divide said cylinder into at least two chambers, and (3) means for connecting said intake air distributor to one .of said chambers and where said second status indicating means includes null-detecting means connected across said primary winding for indicating the status of said pressure measuring means whereby leakage in said diaphragm causes said nulldetecting means to move in a first direction and a 18 vacuum leak or open primary circuit causes said null detector to move in a second direction.

31. Apparatus as in claim 30 where said second status indicating means includes null-detecting means connected across said secondary winding for detecting an open circuit in said secondary winding.

32. Apparatus as in claim 28 where said control means includes means for generating a third interrogation signal and where said sensing means includes temperature sensing means for generating a third sensing signal representative of said ambient temperature in response to said third interrogation signal applied thereto from said control means and where said defect detecting means includes third status indicating means responsive to said third sensing signal and said third interrogation signal for indicating the status of said temperature sensing means or said control means.

33. Apparatus as in claim 32 where said temperature sensing means includes temperature-sensitive, resistive means located in the crank case and cylinder head of said engine for generating said third sensing signal. the magnitude of which is a function of said ambient temperature and where said third status indicating means includes means responsive to said third sensing signal for indicating the desired presence thereof whereby said third status indicating means. in response to said third interrogation signal, indicates the presence of an open circuit or very high resistance in said temperature sensing means and said third status indicating means, in response to the absence of said third interrogation signal, indicates the presence of a short circuit or very low resistance in said temperature sensing circuit.

34. Apparatus as in claim 24 where said control means includes means for generating a first interrogation signal and where said sensing means includes speed sensing means for generating a first sensing signal representative of the speed of said engine in response to said first interrogation signal applied thereto from said control means and where said defect detecting means includes first status indicating means responsive to said first sensing signal and said first interrogation signal for indicating the status of said speed sensing means or said control means.

35. Apparatus as in claim 34 where said speed sensing means includes means responsive to the rotation of the ignition distributor for generating said first sensing signal, the frequency of which is a function of said engine speed and where said first status indicating means includes means responsive to said first sensing signal for indicating the desired presence thereof whereby said first status indicating means, in response to said first interrogation signal, indicates the presence of an open circuit or very high resistance in said speed sensing means and said first status indicating means, in response to the absence of said first interrogation signal, indicates the presence of a short circuit or very low resistance in said speed sensing means.

36. Apparatus as in claim 35 where said means responsive to the rotation of the ignition distributor includes at least one pair of contacts successively opened and closed in response to said rotation to generate said first sensing signal and where the said very high resistance condition indicated by said first status detecting means is corrosion of said contact pair.

37. Apparatus as in claim 24 where said defect detecting means includes fourth status indicating means 19 responsive to said control signal applied to said fuel injection means for indicating the status of said fuel injecting means or said control means whereby said fourth status indicating means, in response to said control signal, indicates the presence of an open circuit or very high resistance in said fuel injection means and said fourth status indicating means, in response to the absence of said control signal, indicates either the presence of a short circuit or very low resistance in said fuel injection means or a defect in said control means.

38. Apparatus as in claim 24 including an internal combustion engine and where said reference signal generator means includes means for generating a plurality of control signals respectively applied to a plurality of said fuel injection means whereby complete combustion in each of the plurality of the engine cylinders connected to said fuel injection means is enhanced so that exhaust pollution is lowered.

39. Apparatus as in claim 24 where said reference signal generator means includes means for shaping said reference control signal so that the leading edge thereof is gradually sloped whereby the life of the valve stem and seat of said fuel injection means is prolonged.

40. Apparatus as in claim 24 where said control means includes means for sensing the height of said engine with respect to a predetermined altitude for generating a height signal and means responsive to the height signal and said sensing signals for generating said control signal.

41. Apparatus as in claim 24 where said sensing means includes means responsive to the position of a throttle valve in the air intake manifold for generating a throttle valve sensing signal and where said defect de- 20 tecting means includes fifth status indicating means for indicating the status of said throttle valve.

42. Apparatus as in claim 41 where said fifth status indicating means is a first lamp whereby a vacuum leak in the low vacuum end of said air intake manifold is detected by rapid, irregular flickering of said first lamp.

43. Apparatus as in claim 24 where said sensing means includes second pressure sensing means responsive to full load vacuum in the air intake manifold for generating a full load vacuum sensing signal and where said defect detecting means includes sixth status indicating means for indicating the status of said second pressure sensing means.

44. Apparatus as in claim 43 where said sixth status indicating means is a second lamp whereby said second lamp indicates a vacuum leak in the high vacuum end of said air intake manifold, if present.

45. Apparatus as in claim 24 including a floating ground within said control means where said sensing means includes means connected to said floating ground within said control means for generating a circuit imbalance signal whenever components within said control means are defective and where said defect detecting means includes seventh status indicating means for indicating the status of said components within said control means.

46. Apparatus as in claim 45 where said fifth and seventh sensing means are included in a common status indicating means, the fifth status indicating means being operative when the throttle valve is closed and the seventh status indicating means being operative when the throttle valve is opened.

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Classifications
U.S. Classification73/114.45
International ClassificationF02D41/00, F02D41/26, G01M15/04, F02D41/22, G01M15/05
Cooperative ClassificationF02D41/22, F02D41/266, G01M15/05
European ClassificationF02D41/26D, G01M15/05, F02D41/22