US 3745817 A
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United States Patent 1 1 1111 3,745,817
Williams et al. 14 1 Jul I7, 1973 ENGINE TEST METHOD AND APPARATUS  References Cited  Inventors: Malcolm Williams, Solihull; UNITED STATES PATENTS Duncan Barry Hodgson, Whitnash, 3,319,613 5 1967 Begley et al. 123 32 EA both of England 3,272,187 9/1966 Westbrook et al. 123 32 EA  Assignee: Jose h Lucas (Industries) Limited,
Bimfingham, England Primary Examiner-Jerry W. Myracle Att0rney-l-lolman & Stern  Filed: Nov. 9, 1971 21 Appl. No.: 196,954 [571 ABSTRACT An engine is tested by deriving a first digital signal rep- [3()] F i A li ti P i it D t resentative of a first engine parameter and a second digital signal representative of a second engine parame- Nov. ll, 1970 Great Britain ..53546/70 ter. These signals provide inputs to a semi-conductor matrix which produces a digital output signal deter- U-S- Cl. 17.3, A mined the values of the input ignals the output ig- [5 1] Int. Cl. G0lm 15/00 nal being used to control an engine characteristic, The Field of Search 119 1 selections within the matrix are chosen for each combil23/32 EA nation of input signal so that for each combination of input signals, the output signal exercises the required control of the engine characteristic.
2 Claims, 1 Drawing Figure ENGINE TEST METHOD AND APPARATUS This invention relates to engine control systems of the kind in which any two of three engine parameters, namely engine speed, manifold pressure (which can of course be a negative pressure) and throttle angle are used to provide two signals, the signals providing inputs to a diode or other suitable semi-conductor matrix, the matrix being designed to give an output determined by both input signals and this output being used to control an engine characteristic. The invention is particularly concerned with control systems for engines used in road vehicles and in most cases the engine characteristics controlled by the system is the injection of fuel to the engine, although, where the engine has a spark ignition system, the ignition timing or a combination of the timing and fuel injection could be controlled.
The object of the invention is to provide a convenient method of testing an engine which facilitates the manufacture of a control system of the kind specified.
The invention further resides in a method of testing an engine comprising deriving a first digital signal representative of a first engine parameter and a second digital signal representative of a second engine parameter, each of said signals providing an input to a semiconductor matrix which produces a digital output signal determined by the values of the input signals, said output signal being used to control an engine characteristic, and selecting the connections within the matrix for each combination of input signals so that, for each combination of the first and second digital signals, said output signal exercises the required control of said engine characteristic.
Preferably, said matrix is a diode matrix in which the diodes are detachable so that the positions of the diodes within the matrix can be altered so as to vary the connections within the matrix.
The invention further resides in apparatus for performing the method.
The accompanying drawing is a diagrammatic illustration of a device for use in the manufacture of a fuel injection control system according to one example of the invention.
Referring to the drawing, there is provided a transducer 8 which produces an electrical signal representing the throttle angle of the engine with which the system is employed. The electrical signal from the transducer 8 .is in the form of a 3 bit binary word which is fed to control means 11 which serves to energise one of 8input lines 134 to 13h, the input lines 13a to 13h fonning part of a diode matrix unit 10, the construction of which will be described later. The unit 10 further includes 8 sets of input lines 16a to 16h, each of the lines 13a to 13h crossing each of the sets of lines 16a to 16h. Although in the example shown there are 8 input lines 13 and 8 sets of lines 16, it will be appreciated that the number of lines can be more or less than this figure. Moreover, although in the example shown each set of lines 16 contains 5 lines, they can be more or less lines in each set 16.
There is further provided a second transducer 9 which produces an electrical signal representing engine speed, the signal being in the form of a 3 bit binary word which is fed to control means 12, which energises one of a set of lines 14a to 14h. The lines 14a to 14h are connected to a switching device 15 having 8 sets of switches 15a to 15k respectively. The arrangement is suchthat when a signal appears on the line 14a, the
switches 15a connect the lines 16a to 5 output lines 21 coupled to a decoder 22, the output from which is fed to injection means 23 controlling the quantity of fuel supplied to the engine.
The lines 16 and 13 are interconnected by diodes in a manner to be described. In the drawing, the connections between the first two sets of lines 16a and 16b and the lines 13 are shown, each dot representing a diode connection. Suppose that the value of throttle angle is such that the line 13a is energised, and the engine speed is such that the line 14a is energised, then the switches 15a connect the lines 16a to the decoder 22, and the decoder 22 will receive a signal of the form 10,000, where 1 represents the diode connection between the line 13a and the first of the set of lines 16a. If the parameters now change in such a manner that the line 13g and the line 14b are energised, then the decoder 22 will receive a signal 01,111. Thus, it will be appreciated that the unit 10'produces an output dependent on the two input signals controlled by the decoders, and controls the fuel in accordance with the connections within the unit 10.
The unit 10 includes a base plate in the form of a peg board 31 above which the lines 13 and 16 are supported by pegs (not shown). The lines 13 extend in a first plane above the board 31, the lines 16 extend in a second plane above the board 31 and at right angles to the lines 13. Each of the lines 13 crosses each of the lines 16 but is spaced from the lines 16. The design of the unit 10 is such that any line 13 can be connected to any line 16' by one of a number of semi-conductor diodes each of which can be detachably engaged between a line 13 and a line 16 to electrically connect the lines. In the drawing, which illustrates the device in use, a number of diodes are shown connected between the lines 13 and the first two groups of lines 16, the diode connections being indicated by the dots previously referred to. During the manufacture of an engine control system, the engine speed and the throttle angle of the engine are set at predetermined values such that the line 13a is energised andthe line 14a is energised, energisation of the line 14a serving to couple the lines 16a to the output lines 21. The line 13a is connected to the lines 16a by l or more diodes which may be chosen arbitrarily, or with some prior knowledge of the engine characteristic, and as shown the output lines 21 will receive a signal 10,000. The signal on the output lines 21 serves through the decoder'22 and the injection means 23 to govern the amount of fuel supplied to the engine for the predetermined throttle setting and engine speed, and the perfonnance of the engine under these circumstances is inspected. The nature of the inspection dependson the intention of the designer, and by way of example the intention could be to maximise engine performance, or to minimise exhaust pollution.
When the engine characteristic has been inspected, the designer then attempts to improve the situation by varying the diode connections. It will of course be appreciated that the connections chosen may not provide the required results, and the next step may, merely by way of example, be to insert another diode at the connection of the line 13a to the line so that the lines 21 receive a signal 1 1,000. This process continues until the optimum engine condition is reached. The engine speed is then kept constant, but the throttle angle changed so that the line 13b is energised instead of the line 13a. The diode connections between the line 13b and the lines 160 are then varied in the same way to give the best possible result. This procedure continues with all the sites in the matrix, the term site" being used to indicate the position at which a line 13 can be connected by up to 5 diodes to a set of lines 16.
It will of course be appreciated that once the required diode positions have been found in the manner described, then diode matrix units can be manufactured on a production basis for use in engine control systems.
The arrangement described above, whereby the diode connections are all found empirically, is somewhat time consuming if the designer has no idea of the most likely diode connections at any given site. In practice, the designer may well be aware of the approximate connections which will be needed, and so not every possible combination of diodes at every site has to be attempted, so that the overall length of time taken to select the diode connections is less than appears. However, in some circumstances the designer may not have any advance information whatsoever, and in such a case it is possible to reduce the time taken to select the diode positions in the following manner. The engine speed and the throttle angle are varied as before so that the site where the line 13a crosses the line 16a is inspected. However, the lines 21 are disconnected from the switches 15, and are connected instead through 5 manually operable switches respectively to a power source. Closing of one of the 5 manually operable switches feeds a signal 1 to the decoder 22, and in this way the decoder 22 can be fed with a digital signal which simulates the insertion of diodes into the unit 10. It is far quicker for an operator to manipulate the switches than to insert the diodes in the matrix unit, and when the manipulation of the switches is completed to give the best possible result, then the diodes are inserted at the appropriate site on the unit in accordance with the positions of the switches, so that if the first three switches are closed and the last two are open, diodes are inserted to connect the line 13a to the first three of the lines 160, but not to the last two of the lines 16a. This action is repeated for each site, and considerably reduces the time necessary for establishing the diode positions. It is necessary after finding the diode positions with the switches to insert the diodes in the unit itself and then to repeat the tests, in case some of the diodes need to be moved. During the repeat test, by virtue of the prevailing dynamic conditions when the engine is used in conjunction with the unit 10 the switches can again be used instead of the diodes, as long as the diode connections are all present, and the lines 21 are coupled to the switches 15 or to the manually operable switches at any given instant.
1. A method of testing an engine comprising deriving a first set of digital signals representative of a range of values of a first engine parameter and a second set of digital signals representative of a range of values of a second engine parameter, feeding one signal from the first set representing one value of the first engine parameter and one signal from the second set representing one value of the second engine parameter to a semiconductor matrix which produces a digital output signal determined by the values of the signals fed to the semi-conductor matrix, said output signal being used to control an engine characteristic, and selecting the connections within the matrix for said combination of one of the first set of digital signals and one of the second set of digital signals so that, said output signal exercises the required control of said engine characteristics, and then repeating said process for each possible combination of signals from the first set and the second set.
2. Apparatus for testing an engine comprising in combination a first transducer for deriving a first digital signal having one of a plurality of values representing a range of values of a first engine parameter, a second transducer for deriving a second digital signal having one of a plurality of values representative of a range of values of a second engine parameter, a diode matrix to which the signals from said transducers are applied, said diode matrix incorporating detachable diodes so that the positions of the diodes within the matrix can be altered so as to vary the connections within the matrix, and engine control means operable by the output from the diode matrix to control said engine characteristic. i t =8