US 3927654 A
A fuel supply system for an internal combustion engine including an injector for each cylinder. The quantity of fuel injected during each engine cycle is controlled by regulating the pressure of the fuel supplied to the injectors, and at intermediate engine speeds with full open throttle, a pressure regulator module functions to regulate the fuel pressure. The module responds to engine speed to modify the pressure as a function of engine speed. A governing device separate from the module governs engine speed at idle and maximum speeds. The throttle includes a pressure regulating mechanism, separate from the module, which operates at part throttle positions to maintain a selected pressure.
Claims available in
Description (OCR text may contain errors)
United States Patent Perr 5] Dec. 23, 1975 1 1 FUEL SUYPLY SYSTEM 3,598,097 8/1971 Eheim 123/140 FG 3,631,743 [/1972 Eckert 123/140 FG [751 Julms Columbus, 3,648,673 3/1972 Knape 123/140 F0  Assignee; Cummins Engine Company, Inc. 3,314,072 6/1974 Gillespie 123/139 ST Columbus, Ind. E I Primary Examiner-Wendell Burns  Flled' 1973 Assistant Examiner-Paul Devinsky  Appl. No.; 390,605 Attorney, Agent, or Firm-Hibben, Noyes & Bicknell 52 11.8. C1. 123/140 FG; 123/140 A; 123/140 R [571 ABSTRACT  Int. Cl. F02D 1/04; F02D 1/06 A fuel supply system for an internal combustion en-  Field of Search 123/ 140 F6, 140 J, 140 A, gine including an injector for each cylinder. The quan- 123/140 R tity of fuel injected during each engine cycle is controlled by regulating the pressure of the fuel supplied  References Cited to the injectors, and at intermediate engine speeds UN E STATES PATENTS with full open throttle, a pressure regulator module 2,136,959 11/1938 Wimfeild 123/139 AW fmcmns m regulate the fuel 'F The "mdule 2,670,725 3/1954 Cummins 123/140 FG i ensme speed the FFessure as 3 2,937,637 5/1960 11613611 123/140 R function of engme speed- A govemlng device Separate 3,036,565 5/1962 Reiners 123/139 AF from the module g r s ngin spe d at idle and 3,058,455 10/1962 Hofer et al 1231140 R maximum speeds. The throttle includes a pressure reg- 3,l43,l04 8/1964 Curnmins et a1... 123/140 R ulating mechanism, separate from the module, which 3,159,152 12/1964 Reiners [23/140 R operates at part throttle positions to maintain a e- 3,185,140 5/1965 Cummins 123/140 lected pressuw 3,319,568 5/1967 Repko et al. 123/140 PG 4 3,319,613 5/1967 Begley et a1.. 1231139 AW 16 Claims, 4 Drawing Figures 0 2 J X 2 ll DAMPER /f/ STRAINER w RETURN ZQDFMQ U.S. Patent Dec. 23, 1975 Sheet 2 of 2 3,927,654
J46-f g9 u 143 I g I (n :3 g5 i ,,.7 SIGNAL ENGINE SPEED J47 R. P. M.
SPEED REPRESENTATIVE SIGNAL FUEL SUPPLY SYSTEM Internal combustion engines wherein fuel is injected into the engine cylinders also of course include a fuel supply system for delivering fuel to injectors for injection into the engine cylinders. Such a supply system usually includes a fuel supply rail connected to the injectors, a fuel tank, a pump for delivering fuel from the tank to the supply rail, and a return rail connected to the injectors for carrying excess fuel away from the injectors.
Reiners U.S. Pat. No. 3,159,152 discloses such a fuel system wherein the quantity of fuel injected into the cylinders in each engine cycle is determined by the pressure of the fuel in the supply rail. Each injector includes a metering or feed orifice having a fixed size, through which the fuel passes in flowing from the supply rail into the injector. Since the quantity of fuel flowing through an orifice is a function of the orifice size, the length of time the orifice is open (the orifice size and the time being constant for a constant engine speed), and the fuel pressure, the quantity may be controlled by regulating the fuel pressure.
In ordinary engine operation, it is advantageous to have the rail pressure increase with increasing engine speed so that a sufficient quantity of fuel may be metered into the injectors. If the rail pressure were constant, the quantity would decrease because the metering time interval shortens with increasing speed. In addition, it is desirable to regulate the supply rail pressure to obtain an advantageous torque curve, which is a curve of the engine torque as a function of engine speed at full open throttle.
In the above Reiners U.S. Pat. No. 3,159,152, the fuel pressure with the throttle fully open is regulated by an engine driven centrifugal mechanism which functions as a governor to control the flow of fuel to the supply rail at idle and at maximum engine speeds, and which also functions as a fuel pressure regulator at engine speeds between idle and maximum. A disadvantage of such a fuel supply system is that the governing and torque curve shaping functions are interwoven and one cannot be changed without affecting the other. Therefore, there is limited flexibility in torque curve shaping in such a system.
There are other patents, such as U.S. Pat. Nos. 2,670,725, 2,727,503, 2,727,498 and 2,749,897, wherein a pressure regulator is provided in such a system. In U.S. Pat. No. 2,749,897 a pressure regulator is provided to shape the torque curve, and a separate centrifugal mechanism is provided which acts as a governor at idling and maximum speeds. Such systems have the disadvantage that the torque curve shaping device does not respond to engine speed nor is it readily adjustable.
It is an object of the present invention to overcome the foregoing disadvantages by providing a fuel supply system wherein the torque curve shaping and the speed governing functions are separated thereby increasing system flexibility, wherein the torque curve shaping function responds to engine speed, wherein governed operation may be obtained for all engine speeds, wherein the torque curve shape may be changed without affecting the governing function, and wherein constant pressure, part throttle curves are obtainable to increase stability of engine operation.
A fuel supply system embodying the invention comprises a pump adapted to supply fuel at a rate which is a function of engine speed, an engine speed responsive governor connected to receive fuel from said pump and regulating the fuel pressure at idle and maximum engine speeds, fuel injector means connected to receive fuel from said governor and injecting fuel into cylinders of the engine, a pressure regulator module connected in the fuel flow path between said pump and said governor and regulating fuel pressure at intermediate engine speeds between idle and maximum speeds, and signal generating means responsive to engine speed and generating a signal which is a function of engine speed, said module being connected to receive said signal and to regulate fuel pressure as a function of engine speed. Also preferably provided is a throttle which maintains the pressure of the fuel flowing to the fuel injector means constant for any given part throttle setting.
Other objects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying figures of the drawings, wherein:
FIG. 1 is an illustration of a fuel supply system embodying the invention;
FIG. 2 is a sectional view taken on the line 2-2 of FIG. 1;
FIG. 3 shows curves illustrating the operation of the fuel supply system;
FIG. 4 is a schematic illustration of an alternate construction of a part of the fuel supply system shown in FIG. 1.
With reference to FIG. I, an engine having a fuel supply system embodying the invention includes a fuel supply tank 10, a plurality of fuel injectors 11, one for each cylinder of the engine, and speed governing and fuel pressure regulating apparatus 16 for drawing fuel from the supply tank 10 and delivering it to the injectors 11.
The injectors 11 may be of the character shown, for example, in the Perr U.S. Pat. No. 3,351,288 or in the Reiners et al. U.S. Pat. No. 3,544,008. Such an injector includes an injection chamber connected to a supply rail 18 by a feed or metering orifice, indicated schematically by the reference numeral 17 in FIG. 1. Fuel flows from the fuel supply rail 18 through each of the metering orifices 17 to the injection chambers of the injectors, and since the size of the orifices 17 is fixed, the quantity of fuel metered into each injection chamber will be determined by the pressure of the fuel in the supply rail 18 and by the length of time the orifice I7 is open. The length of time the orifice 17 is open varies with engine speed and decreases as engine speed increases. In a fuel supply system of this character, the quantity of fuel metered into an injection chamber and injected into an engine cylinder in each engine cycle is regulated by varying the pressure of the fuel in the supply rail 18. A return rail 19 is connectedbetween each of the injectors I1 and, in this instance, the fuel supply tank 10, and returns surplus fuel to the tank 10. The pressure within the tank 10 and in the return line 19 is at substantially atmospheric pressure.
The governing and regulating apparatus 16 comprises a positive displacement pump 22 such as gear pump which is connected by a drive connection 23 to be driven by the engine. The drive connection 23 drives the pump at a rate which is a function of engine speed, and consequently, the rate at which the fuel is pumped out of the tank 10 is also a function of engine speed. A
fuel line 24 connects the intake of the pump 22 with the tank 10, and another fuel line 26 connects the pump output to a fuel strainer 27. A pulsation damper 28 is preferably connected to the fuel line 26 in order to remove any pressure pulses that may be produced by operation of the pump 22.
Fuel from the strainer 27 flows through a fuel line 29 to a centrifugally controlled governing device 31. The device 31 includes a housing 32 (FIGS. 1 and 2) which supports a sleeve 30, the sleeve having a plunger bore 33 formed therein, and a reciprocable and/or rotatable plunger 34 is movably mounted in the bore 33. A passage or port 36 is formed through the wall of the housing 32 and a plurality of ports 36a are formed through the sleeve 30, the ports 36 and 36a connecting the fuel line 29 with the plunger bore 33. The plunger 34 may, for example, have an elongated generally cylindrical configuration and include an annular groove 37 which is always in registry with the port 36. The housing 32 and the sleeve 30 also may have idle ports 38 and 38a, respectively, for automotive operation, and maximum speed ports 39 and 39a, respectively, formed therethrough which are also, at certain times during the operation of the engine, in registry with the groove 37. As shown in FIG. 2, the ports 36, 38 and 39 are angularly spaced in the body 32, and two ports 39 may be provided. Each of the ports 36a, 38a and 39a may actually consist of a set of angularly spaced ports, each set of ports being connected by an annular groove. Further, the outer periphery of the body 32 at circumferentially spaced points may be machined flat as indicated at 36b and 39b. The idle port 38 is connected by a fuel line 41 to the supply rail 18, a shutdown valve 42 preferably being connected between the line 41 and the supply rail 18. As will be described hereinafter, the device 31 serves as a governor at maximum and idle speeds, and also serves as an all-speed governor.
The maximum speed port 39 is connected by another line 43 to a throttle 44, comprising a housing 46 having a throttle plunger 47 reciprocably mounted in a bore 48 formed in the housing 46. A wall 49 closes one end of the housing 46, and a port 51 in the wall 49 is connected to the line 43. A chamber 60 is formed between the wall 49 and the upper end of the plunger 47. An annular groove 52 is formed in the plunger 47, dividing the plunger 47 into upper and lower portions. A passage 53 is formed in the plunger 47 from the groove 52 to the end which is adjacent the wall 49. The other end of the plunger 47 is engaged by a compression spring 54 which is positioned between the plunger 47 and a cam follower 56. A pivotally mounted cam 57 having a manually operated lever 58 attached thereto, engages the cam 57. A port 55 is formed in the wall of the housing 46 adjacent the upper edge of the groove 52, and is connected by a line 59 to the line 41.
In the operation of the throttle 44, fuel flows from the line 43 into the chamber 60. The fuel pressure pushes the plunger 47 downwardly against the force of the spring 54. The port 55 is located relative to the lower edge of the upper portion of the plunger such that the lower edge increasingly closes off the port 55 as the plunger 47 is forced downwardly by fuel pressure in the chamber 60. The cam 57 and the lever 58 enable an operator to adjust the compression of the spring 54 and, consequently, the amount of force required to move the plunger 47 downwardly. Therefore, at any given setting of the cam 57, the throttle also acts as a pressure regulator because increased pressure in the chamber 60 results in increased closing off of the port 55. As fuel pressure decreases, the port 55 opens. The net result is that the throttle holds the fuel pressure in the rail 18 substantially constant for a given throttle setting. The throttle 44 thereby serves as an automotive governor and provides increased engine stability because it maintains the rail pressure constant at various part throttle settings.
With reference again to the centrifugally controlled device 31, the position of the plunger 34 is controlled by a compression spring 61 and two weights 63 and 64 connected to the drive connection 23 to be rotated at a rate which is a function of engine speed. As the engine speed increases, the two weights 63 and 64 pivot on pins 66 and move the plunger 34 downwardly against the force of the spring 61. Of course, as engine speed decreases, the weights 63 and 64 pivot to permit the spring 61 to return the plunger 34 upwardly.
The spring 61 is positioned between lower and upper cup shaped supports 71 and 72 which are slidably mounted in the housing 32 below the lower end of the plunger 34. Holes 73 are preferably formed in the two supports 71 and 72 to permit fuel to flow into and out of the space between the supports as the spring 61 expands and contracts. The lower support 71 rests on a manually adjustable, pivotally mounted lever 70. The upper support 72, which is adjacent the plunger, carries a cupped member 76 which fits around the lower end of a circular adaptor 77. A small ball is interposed between the support 72 and the member 76.
The adaptor 77 has a central spill passage 78 formed therethrough, through which fuel flows as will be explained hereinafter. The member 76 includes an outer circular wall portion 79 which fits around the adaptor 77. Spill ports 81 are formed in the wall 79, and an O-ring 83 is mounted in a groove formed in the adaptor 77, between the passage 78 and the ports 81. in the position of the parts shown in FIG. 1, the inner wall of the member 76 sealingly engages the O-ring 83 and prevents fuel flow out of the passage 78. When sufficient fuel pressure exits in the passage 78, the member 76 is forced downwardly against the force of the spring 61 and separates from the O-ring 83, thus spilling fuel from the passage 78 to the ports 81. Any fuel flowing out of the ports 81 flows through ports 84 in the housing 32 and through a line 85 to the return line 19.
Fuel flowing through the passage 78 is derived from an axially extending passage 91 formed from the lower end of the plunger 34 upwardly to approximately its midpoint. The adaptor 77 is sealingly connected to the lower end of the plunger 34, and the passage 78 is aligned with the passage 91. At its upper end, the passage 91 is connected to the groove 37 by a plurality of radial ports 92. An insert 93 having a restricted passage or orifice 94 formed therethrough, is fastened, as by a threaded connection, within the passage 91 below the ports 92. Further, another plurality of radial ports 95 are formed through the plunger 34 from the passage 91 to an annular groove 97 formed in the outer surface of the plunger. Ports 98 and 980 are formed in the housing 32 and the sleeve 30, respectively, and connect the groove 97 to a line 99.
The mechanism 31 acts as a governor at idling and maximum speeds. At idling speed, the weights 63 and 64 are approximately in the position shown in FIG. 1 and the plunger 34 is upwardly displaced. The idle port 38a is located in the sleeve 30 such that it is opened by the upper edge of the groove 37 when the plunger 34 is upwardly displaced at idling speed, as shown in full lines in FIG. 1. If the engine tends to speed up, the weights 63 and 64 move the plunger 34 downwardly causing the upper edge of the groove 37 to increasingly close the idle port 380. Such closure will decrease the quantity of fuel supplied to the line 41 and the rail 18 and result in a drop in engine speed. The weights 63 and 64 react to the speed drop by permitting the plunger 34 to move upwardly, due to the force of the spring 61, to maintain a sufficient supply of fuel to the injectors to keep the engine running. It will be apparent therefore that the interaction between the upper edge of the groove 37 and the idle port 380 provides a governing action at idle speed which maintains the engine idling at the desired speed.
The maximum speed port 39a is located in the sleeve 30 such that it will be closed by the upper edge of the groove 37 when the engine speed exceeds the maximum allowable speed of the engine. If the engine speed reaches the maximum allowable speed, the upper edge of the groove 37 starts to close off the port 39a and thus reduce the quantity of fuel flowing to the injectors 11. Consequently, the interaction between the upper edge of the groove 37 and the maximum speed port 39a serves to control or govern the maximum engine speed and thereby protect the engine.
At intermediate engine speeds between idle speed and maximum speed, the groove 37 is in the dashed line position 40 shown in FIG. 1, wherein the idle port 38a is completely closed and the maximum speed port 39a is fully open. with the throttle cam 57 moved to the fully open position shown in FIG. 1, pressure regulation at intermediate speeds is provided by a pressure regulator module 111 which is connected to the fuel line 29 and is responsive to engine speed. The module 111 includes a housing 112 having a bore 113 formed therein. One end of the housing 112 is open as at 114 and a fuel control insert 116 is fastened in the opening, an orifice 117 being formed in the fuel control insert 116. The size of the orifice 117 thus may easily be changed by providing a number of inserts such as the insert 116, each having a different size orifice, and installing the insert having the desired orifice size. A line or passage 118 connects the fuel line 29 with the orifice 117. A fuel control plunger 119 within, the housing 112 is urged by a compression spring 121 in the direction of the insert 116, and with little or no fuel pressure in the line 29, the plunger 119 closes the orifice 117. The space within the housing 112 around the upper end of the plunger 119 is connected by a port 122 formed in the housing 112 and by a fuel line 123 to the fuel return line 19. Thus, any fuel bypassed from the line 29 through the orifice 117 when the plunger 119 is displaced downwardly flows to the return line 19.
it will be apparent that if the force exerted by the spring 121 on the plunger 119 were not adjustable, the module 111 would operate as a constant pressure regulator and would hold the pressure in the line 29 substantially constant when the pressure in the line 29 exceeds the strength of the spring 121. In accordance with the present invention, however, the force exerted by the spring 121 may be varied by a signal that is representative of engine speed, and consequently, the module 1 1 1 operates to regulate the pressure in the line 29 in accordance with engine speed to obtain a desirable torque curve.
To this end, another port 126 is formed through the wall of the housing 112 below a cup shaped piston 127 which is movably mounted within the housing 112 below the plunger 119 and the spring 121. A compression spring 128 is positioned between the upper end of the piston 127 and a ledge 129 formed within the housing 112. The upper end of the spring 128 does not engage the ledge 129 until the piston 127 and the spring 128 have moved upwardly slightly. A closure 131 and a snapring 132 are fastened in the lower end of the bore 113, and form a stop which limits the maximum extent of downward movement of the piston 127. The compression spring 121 is located between the lower end of the plunger 119 and the piston 127, and it will be apparent that if the pressure within the housing 112 between the piston 127 and the closure 131 is sufficient to move the piston 127 upwardly, such upward movement of the piston 127 will increase the force of the spring 121 tending to move the plunger 119 upwardly. This increased force and upward movement of the plunger 119 reduces the effective size of the orifice 117, thereby increasing the pressure in the fuel line 29 because of the decrease in the amount of fuel being bypassed from the line 29 to the return line 19.
The previously mentioned speed representative signal appears at the port 126 and may be derived from a separate mechanism, but in the present instance it is derived from the device 31. The port 126 is connected to the line 99, and the pressure of the fuel in the line 99 constitutes a speed representative signal. When the member 76 engages the seal 83 on the adaptor 77, no fuel flows from the passage 91. However, if the pressure of the fuel in the passage 91 is sufficient, it forces the member 76 downwardly against the force of the spring 61 thereby permitting bypass flow of fuel through the port 92 and the orifice 94, through the passages 91 and 78 and out of the ports 81. This fuel flows out of the housing 32 through the ports 84 which are connected to the return line 19 by the line 85.
The amount of force exerted by the spring 61 to urge the member 76 upwardly may be adjusted by pivoting the lever which has one end engaging the underside of the support 71 at the lower end of the spring 61.
Considering the operation of the fuel supply system illustrated in FlG. 1, during cranking and starting of the engine, the drive connection 23 turns slowly and the idle port 38 of the centrifugally operated device 31 is open. The pump 22 draws fuel from the tank 10 and delivers it to the fuel line 29. The fuel flows through the ports 36 and 36a, the groove 37 and out of the idle ports 38 and 380, through the line 41 and the valve 42 to the supply rail 18 for injection into the engine cylinders. The throttle 44 is set to close the port 55. The pressure in the line 29 during cranking and starting is normally quite low because of the reduced speed of the engine driven pump 22, and consequently the pressure is not sufficient to force the plunger 119 downwardly against the spring 121 and open the orifice 117, and is not sufficient to force the member 76 downwardly against the force of the spring 61. Therefore, full pressure of the fuel pump 22 is delivered to the injectors 11 during cranking and starting operation.
After the engine starts and the throttle 44 is adjusted to a part throttle position by turning the cam 57, the centrifugal mechanism of the device 31 moves the plunger 34 downwardly and the plunger closes the idle ports 38 and 38a. The maximum speed ports 39 and 39a are however open, and consequently, fuel flows through the ports 39 and 39a to the throttle 44, and in normal engine operation at the intermediate speeds, the fuel pressure in the supply rail 18 is regulated by the operator who adjusts the throttle 44. If the throttle 44 is placed in the fully open position shown in FIG. 1, the engine speed will vary with load on the engine. This is illustrated by the curve 142 (FIG. 3) which represents rail 18 pressure vs. speed with fully open throttle. With reference to FIG. 3, the pressure in the fuel line 29 increases as indicated by the portion 141 of the pressure vs. engine speed curve 142, as the drive connection 23 turns faster, because of the increased rate of operation of the pump 22. It should be understood that the pump 22 always delivers more fuel than is required for engine operation. When the pressure in the fuel line 29 reaches a predetermined value, indicated by the knee 143 of the curve 142, this value being determined by the strength of the compression spring 121, the plunger 119 is moved downwardly by the fuel pressure in the line 29 to partially open the orifice 117. A portion of the fuel flowing from the pump 22 is then bypassed, through the line 118 and the orifice 117 and the bypass port 122 and to the return line 19. In addition, fuel from the line 29 also flows to the port 36 formed in the housing 32 of the device 31. The fuel flowing to the port 36 flows through the groove 37, the ports 92, the orifice 94 and the passage 91, and this fuel pressure is sufficient to force the member 76 downwardly against the force of the spring 61. The effective size of the opening between the lower end of the adaptor 77 and the member 76 will determine the amount of fuel bypassed through the ports 81 and 84 and the line 85 to the return line 19, and this effective size of the opening is determined by the speed of the engine turning the weights 63 and 64, by the fuel pressure in the passage 91, and by the strength of the spring 61. The amount of fuel bypassed through the passage 91 determines the pressure in the line 99 and in the port 126, and since this pressure varies as a function of the speed of the engine, the pressure at the port 126 constitutes a speed representative pressure signal. The orifice 94 maintains pressure in the line 43 even though fuel is bypassed through passage 91.
The pressure of the fuel in the port 126 is applied to the underside of the piston 127 and tends to move the spring 121 and the piston 127 upwardly, increasing the force of the spring 121 on the piston 119. This increased force tends to reduce the size of the orifice 117 and decrease the amount of bypassed fuel flowing to the line 123, which results in an increase in the pressure in the fuel line 29.
With reference again to the curves of FIG. 3, the pressure of the fuel during intermediate engine speeds is represented by the portion 144 of the curve 142 between the knee 143 and an upper knee 146. If the module III were a simple pressure regulator and did not respond to engine speed, the portion 144 of the curve would be a substantially straight constant pressure curve. However, in accordance with the present invention, the pressure of the speed representative signal gradually increases as represented by the curve 147, thereby gradually increasing the force exerted by the spring 121. Consequently, the fuel pressure in the rail 18 gradually increases with increasing engine speed, as indicated by the portion 144 of the curve 142.
At high engine speeds, the piston 127 is moved upwardly sufficiently by the speed representative signal to move the outer spring 128 against the ledge 129 formed within the housing 112. Consequently, the spring 128, in addition to the spring 121, resists upward movement of the piston 127, and therefore the curve 142 flattens above the knee 146, as indicated by the numeral 148.
The foregoing described fuel pressure curve 142 which exists when the throttle 44 is fully open, produces a torque vs. engine speed curve indicated by the numeral 151 in FIG. 3.
If the engine reaches maximum speed, the plunger 34 is moved downwardly by the weights 63 and 64 to the point where the plunger at the upper edge of the groove 37 starts to close the maximum speed ports 39 and 39a, thereby reducing the pressure in the supply rail 18 as indicated by the curve 149 (FIG. 3). The quantity of fuel flowing into the injectors 11 thereby drops, reducing engine speed. When the engine speed reduces, the plunger 34 moves upwardly and the ports 39 and 39a are again opened. Thus, the mechanism 31 operates as a governor at maximum speed as well as a governor at idling speed.
The maximum speed referred to above at which the ports 39 and 39a are closed, may be adjusted by changing the pressure exerted by the spring 61 using the lever 70. If the lever is adjusted to place high compression on the spring 61, the curve 149 (FIG. 3) falls at a relatively high engine speed. If there is light compression on the spring 61, the curve 149 falls at a relatively low engine speed. Consequently, if the throttle 44 is locked in its fully open position, the lever 70 may be adjusted to a desired speed setting and the mechanism 31 will hold the engine at that speed because it holds the fuel pressure at the intersection of the curve 149 with the curve 142. Such governing action is referred to as tractor or all-speed governing because it will hold a set speed at any load. The shape of the portions 144 and 148' may be changed by changing the springs 121 and 128. The spring 121 is preloaded, and the amount of the preload determines the location of the knee 143 of the curve 142. The knee 143 is rounded somewhat due to leakage in the system. The pressure level of the curve 142 depends upon the size of the orifice 117 of the module 111. For example, if a smaller orifice than the one shown is used, the curve 142 will be moved upwardly to higher pressure levels for the various engine speeds.
For automotive governing action, the throttle 44 is adjusted to obtain a desired fuel pressure. Setting of the cam 57 to a part throttle position will result in the plunger at the upper edge of the groove 52 partly closing off the port 55. As previously mentioned, the fuel pressure at which the port 55 is partly closed depends upon the force of the spring 54 which in turn depends upon the setting of the cam 57, and the throttle 44 acts as a pressure regulator at part throttle settings. The constant pressure lines 152 (FIG. 3) represent three different throttle settings. For a constant engine load, the fuel pressure and engine speed will be held constant for any given throttle setting.
The fuel supply system described above has numerous advantages. The characteristics of the pressure regulator module may be easily changed as by selecting a member 116 having the desired orifice size or by changing the springs 121 and 128. The module characteristics may easily be changed without dlsturbmgthe other operating parts of the system to obtain a desired torque curve, and the torque curve shaping parts of the 9 system are separate from the governing function. The mechanism 31 forms an idle speed governor and it provides an all-speed or tractor governing function. The throttle 44 holds the rail pressure constant at different part throttle settings and provides an automotive governing function.
FIG. 4. illustrates an alternate form of fuel pressure regulator module, wherein the fuel pressure drops along a negative pressure curve indicated by dash-dot line 160, shown in FIG. 3, at above a certain engine speed. The module shown in FIG. 4 includes a housing 161 having an orifice 162 formed in one end thereof, which is connected by a passage 163 to a fuel line such as the line 29 in FIG. 1. A plunger 164 closes the orifice 162 at low pressures in the line 29 due to the action of a compression spring 166 which urges the plunger 164 upwardly. When the plunger 164 is moved downwardly due to increased pressure in the line 29 and the passage 163, the effective size of the orifice 162 is increased and fuel is bypassed from the line 29 through the passage 163, the orifice 162, the interior of the housing 161, an outlet port 167, and a return line 168. The plunger 164, in the present example, is slidably mounted in a hole formed in an interior wall 169 of the housing 161, and ports 171 are formed through the wall 169 for the flow of the bypassed fuel.
The spring 136 is supported and urged upwardly by a piston 172 which is movably mounted in the housing 161 below the plunger 164. A second wall 173 is formed interiorly of the housing 161, and the piston 172 is slidably mounted in a hole 174 formed in the wall 173. An inverted cup-shaped member 176 is slidably mounted in the housing 161 below the wall 173 and normally supports the piston 172. Another compression spring 177 is located below the member 177 and urges it upwardly. A port 178 if formed in the wall of the housing 161 between the member 176 and the wall 173, the space between the wall 173 and the member 176 forming a chamber 179. The wall 173 separates the interior of the housing 161 into an upper chamber 181 through which the bypassed fuel flows, and the chamber 179 which receives the speed representative pressure signal. The lower space in the housing 161, indicated by the numeral 182, below the member 176 is connected by a port 183 to the return line 168 so that the underside of the member 176 and the chamber 181 will be at substantially atmospheric pressure.
Both of the springs 166 and 177 are preloaded, and the preload of the spring 177 is substantially greater than that of the spring 166. Further, the area of the top of the member 176 over which the pressure of the speed representative signal acts, is substantially greater than the area of the lower end of the piston 172.
At a low pump pressure in the line 29 and with a low signal pressure at the port 178, due to low engine speed, the plunger 164 closes the orifice 162 and thus prevents any bypass fuel from flowing. When the engine speed increases, the pressure in the line 29 exceeds the preload of the spring 166 and the orifice 132 is opened slightly by forcing the plunger 164 downwardly. This occurs at the knee 143, FIG. 3. In addition, the pressure of the speed representative signal increases and this pressure in the chamber 179 moves the piston 172 upwardly, thus producing the sloped portion 144 of the curve 142. When the preload of the spring 177 is overcome, the member 176 moves downwardly. and removes part of the upwardly directed force on the plunger 172, thus increasing the amount of fuel bypassed and decreasing the pressure in the line 29, as shown by the negative pressure curve 160.
While the invention has been described in connection with an engine including cylinders, it should be understood that it may also be used in other types of internal combustion engines, such as rotary engines, including combustion chambers.
It will be apparent from the foregoing that a novel and useful fuel supply system has been provided. The fuel pump, the module, the centrifugal mechanism including the idling and high speed governors, and the throttle may all be assembled in a compact housing, with the fuel passages between them, and the return line, being formed by bores in the housing. The levers and 58 would of course be accessible from outside the housing, and the lower end of the module 111 would also be accessible from outside the housing so that the module may easily be removed or installed. Since the module may be removed, the springs 121 and/or 128 may be changed, or the size of the orifice may be changed, to produce a desired torque characteristic. It is especially advantageous that the module 111 is separate from the mechanism 31 so that either the torque characteristic or the low and high speed governing characteristic may be changed without changing the other characteristic. The system provides both allspeed governing and automotive speed governing without torque curve distortion and the throttle holds the fuel pressure in the rail constant with changing engine speed, for various part throttle settings, thus improving engine stability.
1. A fuel supply system for an internal combustion engine, comprising an engine driven pump means for drawing fuel from a fuel supply and delivering the fuel to a fuel line leading to injectors of the engine, bypass pressure regulator module means connected to said line for regulating the pressure in said line by bypassing a portion of the pump output, engine speed responsive means separate from said pump means for producing a speed representative signal, said module means being connected to receive said signal and operating to adjust the amount of fuel bypassed as a function of said speed representative signal and thereby regulating the pressure in said line as a function of engine speed and independently of the output of said pump at an intermediate engine speed range, and governor means separate from said module means and connected to said line for regulating the fuel pressure in said line at maximum speed range, said module means and said governor means functioning independently of each other and said module means further functioning in said maximum speed range when said governor means is operative.
2. A fuel supply system as in claim 2, wherein said module means includes a variable size orifice connected to withdraw fuel from said fuel line, and means responsive to said signal for varying the size of said orifice in response to variations in the speed of the engine.
3. A fuel supply system as in claim 3, wherein said signal responsive means tends to change said orifice to a smaller size with increasing engine speed.
4. A fuel supply system as in claim 2, wherein said signal responsive means tends to change said orifice to a larger size at above a predetermined engine speed.
5. A fuel supply system as in claim I, and further including centrifugal means adapted to be connected to be driven by the engine, said engine speed responsive means and said governor means both being operated by said centrifugal means.
6. A fuel supply system as in claim 5, wherein said governor means further regulates the fuel pressure in said line at idling speed range.
7. A fuel supply system as in claim 5, wherein said governor means further includes adjustable means for changing the value of said pressure at maximum speed range.
8. A fuel supply system as in claim I, and further including a throttle connected to said fuel line, said throttle comprising adjustable pressure control means for maintaining a selected fuel pressure in said fuel line.
9. A fuel supply system as in claim 8, wherein said throttle comprises a housing having a plunger movably mounted therein, a chamber formed in said housing and connected to receive fuel flowing in said line, the fuel pressure in said chamber urging said plunger in one direction, spring means connected to said plunger and urging said plunger in the opposite direction, and a fuel passage formed in said throttle which is increasingly closed as the pressure in said chamber increases.
10. A fuel supply system as in claim 9, wherein said throttle further includes manually adjustable means for varying the force of said spring means.
11. A fuel supply system as in claim 1, wherein said module means comprises a housing having a plunger slidably mounted therein, an orifice formed in said housing and one end of said plunger extending to said orifice, a spring urging said plunger in the direction to close said orifice, a port formed in said housing, said orifice being connected to said fuel line and the amount of fuel bypassed from said orifice to said port being dependent upon the pressure of the fuel in said fuel line and the force of said spring, said signal adjusting the force of said spring as a function of engine speed.
12. A fuel supply system as in claim 1, wherein said engine speed responsive means comprises a centrifugal mechanism adapted to be driven by the engine, a movable plunger connected to be moved in one direction by said mechanism, spring means connected to move said plunger in the other direction, bypass passage means extending through said plunger and connected to said line, the amount of fuel bypassed from said line and the pressure in said bypass passage means being a 12 function of the position of said plunger and therefore engine speed, and means connecting said bypass passage means with said module means, said pressure in said bypass passage means comprising said speed representative signal.
13. A fuel supply system as in claim 1, wherein said speed representative signal comprises the pressure of a fluid in a passage which is connected to said module means.
14. A fuel pressure regulating system for an internal combustion engine including at least one injector, a fuel supply tank, and a pump for pumping fuel from the tank at a rate which is a function of engine speed, said system comprising fuel flow means connecting said pump to said injector, engine speed responsive governor means in said flow means and governing the fuel pressure at maximum engine speed, signal generating means connected to the output of said pump and to said governor means for generating a signal having a value which is a function of engine speed, and pressure regulator means connected to said flow means and to said generating means and responding to said signal to regulate the pressure of the fuel in said flow means, said pressure regulator means comprising a housing having a plunger slidably mounted therein, an orifice formed in said housing and one end of said plunger extending to said orifice, a spring urging said plunger in the direction to close said orifice, a port formed in said housing, said orifice being connected to said flow means and the amount of fuel bypassed from said orifice to said port being dependent upon the pressure of the fuel in said flow means and the force of said spring, and means responsive to engine speed for adjusting the force of said spring as a function of engine speed, said speed responsive means comprising a member movably mounted in said housing behind said spring and engaging said spring, movement of said member in one direction increasing the force of said spring and movement of said member in the other direction decreasing the force of said spring, said signal being applied to and moving said member in accordance with engine speed.
15. A system as in claim 14, wherein said signal is applied to said member to move said member in said one direction.
16. A system as in claim 14, wherein said signal is applied to said member to move said member in said other direction.
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