US3431900A

US3431900A - Fuel injection systems

Info

Publication number: US3431900A
Application number: US597435A
Authority: US
Inventors: Harold Ernest Jackson
Original assignee: Petrol Injection Ltd
Current assignee: Petrol Injection Ltd
Priority date: 1965-12-24
Filing date: 1966-11-28
Publication date: 1969-03-11
Anticipated expiration: 1986-03-11
Also published as: GB1156790A; FR1506774A; BE691749A; DE1526540A1; SE337141B; NL6617093A; NL141609B

Description

March 1969 H. EJACKSON FUEL INJECTION SYSTEMS I of 4 Sheet Filed Nov. 28, 1966 March 11, 1969 H. E. JACKSON 3,431,900

FUEL INJECTION SYSTEMS Filed Nov. 28, 1966 March 11, 1969 H. E. JACKSON FUEL INJECTION SYSTEMS Sheet Filed Nov. 28, 1966 March 11, 1969 Filed liov. 28, 1966 FIG. 6.

H. E. JACKSON 3,431,900

FUEL INJECTION SYSTEMS United States Patent 54,793/65 US. (:1. 123-139 5 Claims rm. cl. FtlZm 39/00 ABSTRACT OF THE DISCLOSURE A fuel injection system for an internal combustion engine, in which fuel pressure increases with increasing engine speed and in which, to provide proper fuel supply to the fuel injector nozzles over the whole of the engine operating speed range, the fuel supply path to the injector nozzles has first and second parallel flow branches, connected directly to the nozzles by feed conduits, the flow paths defined by the feed conduits and the nozzles including fixed flow equalising restrictors. In one embodiment, an engine load responsive fuel fiow control valve connects the supply path and the first branch, and the second branch contains an engine load responsive fuel flow conload responsive valve) contains a reference fiow restrictor the fuel pressure drop across which is indicative of fuel supply to the injector nozzles and'is used to control a flow control valve in the second branch to maintain that branch open only at engine speeds below a preselected value. In a second embodiment, the supply branch contains an engine load responsive fuel flow con trol valve located upstream of both the first and second branches. Both the first and second branches include fuel pressure responsive valves, that in the first branch opening at a higher fuel pressure than that in the second branch. The second branch includes a reference flow restrictor and communicates with the first branch downstream of the fuel pressure Valve in the first branch. At low engine speeds (when fuel pressure is low) the first branch is closed and the second branch is open. As engine speed (and fuel pressure) increase, the back pressure across the reference fiow restrictor closes the second branch.

This invention relates to continuous fuel injection systerns in general, both those employing vented injector devices as well as those employing compressed-air atomizing injector nozzles. More particularly, the invention is concerned with fuel supply to the injector devices in such systems.

The invention is concerned with the recognised problem of ensuring adequate fuel supply to the injector devices at low engine speeds, including engine idling speeds, without supplying excessive fuel at higher engine speeds.

According to the present invention, a continuous fuel injection system for an internal combustion engine has a fuel supply conduit connected to fuel injector devices and including an engine drivable fuel pumping device operable to pressurise fuel in dependence on engine speed, the fuelsupply conduit including first and second parallel flow branches, the supply conduit also including a fuel metering vave arrangement operable in response to engine loading to supply fuel to the injector devices via the first branch over the greater part of the engine operating speed range above a selected relative-1y low engine operating speed, and the second branch containing a flow restrictor forming part of a fuel flow control device so operable that fuel passes through the second branch only over a range of engine speeds at the lower end of the speed range and occupying a small proportion of the overall engine speed range.

3,431,900 Patented Mar. 11, 1969 In a preferred embodiment, the fuel metering valve device has a variable area orifice disposed in the first branch. In this embodiment the second branch includes a fixed flow restrictor and a closure valve member operable to close the second branch at engine speeds higher than the small range of engine speeds at the lower end of the overall speed range. In a system in which fuel supply pressure is increased with increasing engine speed over the whole of the operating speed range, the closure valve member can be operably responsive to fuel supply pressure such that it is closed by fuel pressures corre sponding to engine speeds above the selected engine speed.

In another embodiment, in which fuel pressure in the fuel supply conduit is so controlled that during engine operation at speeds higher than the idling speed range, the fuel pressure equals a predetermined constant value and increases beyond that value with increasing engine speed, the first branch includes a first fuel pressure responsive valve member openable at the predetermined fuel pressure to pass fuel via the first branch to the injector devices. The second branch includes a relatively high resistance fixed flow restrictor arrangement and a second fuel pressure responsive valve member openable at a pressure lower than the predetermined fuel pressure to pass fuel through the second branch at engine speeds in the idling speed range, when no fuel passes through the first branch, the amount of fuel passing through the second branch, when the first branch is open, being zero or a negligible value due to the relatively high flow resistance of the flow restrictor arrangement in the second branch.

In systems incorporating a fuel supply arrangement according to the invention, it is preferred that the supply conduit is also connected via a fixed (preferably adjustable), flow restrictor arrangement to a fuel return or bypass line. During operation of such a system, fuel from the supply line passes partly to the injector devices and partly to the return or by-pass line, the flow proportions depending on the flow restriction offered by the injector devices and the restriction offered by the flow restrictor arrangement connecting the supply line to the bypass line.

By way of example, embodiments of the invention will be descibed in greater detail with reference to the accomp'anying drawings, in which:

FIGS. 1 and 4 are schematic illustrations of two sys terns according to the invention,

FIG. 2 shows a modification of part of FIG. 1,

FIG. 3 is a diagrammatic illustration of a component of FIG. 1,

FIG. 5 is a cross-section of a component of FIG. 4,

FIG. 6 is a section on the line VIVI in FIG. 5,

FIG. 7 is a section on the line VII-VII in FIG. 5, and

FIG. 8 is a front view of FIG. 5.

In FIG. 1, there is shown a low pressure continuous fuel injection system for an internal combustion engine. The system has a fuel supply conduit system including a supply line 1 including parallel branches 1A and 1B connected by

lines

2A and 2B to a chamber 3 which in turn is connected to a distribution chamber 4 from which lines 5, containing flow equalising restrictors 6, lead to fuel injector devices 7 disposed in the inlet manifold structure of the engine such that the fuel spray discharged from the injector devices is drawn into the engine cylinders when the inlet valves open. This disposition of the injector devices is illustrated, for example, in copending application No. 8,528/ 65. Down-stream of their connections to the chamber 3, the branches 1A and 1B are connected via fixed adjustable flow restrictors 8A and SE to a fuel b-y-pass line 9.

Fuel is supplied to the supply branch 1 from an engine driven pressurising pump 10 operable to pressurise fuel in the supply line in dependence on engine operating speed so that as engine speed increases, so does the fuel supply pressure. The pump llti is fed by a priming pump 11 that delivers fuel at a constant pressure determined by a relief valve 12, having a vent 17, a lift pump 13 supplying fuel to the priming pump from the fuel tank M of the engine via vapour separator 15. The by-pass line 9 is connected back to the tank 14 via a relief valve 16 having a vent 17, the vapour separator and a check valve 13.

In operation of the system, as so far described, fuel is pumped through the supply line It at a pressure dependent on engine speed, the flow from the supply line dividing between the injector devices 7 and the by-pass line 9 in a proportion dependent on the relation between the flow restrictors 6 and the

flow restrictors

8A, 88. By suitable choice of the flow resistances of these restrictors, circulation of fuel in the lines 1 and 9 can be maintained over the normal range of engine speeds whilst maintaining desired fuel supply to the injector devices.

The amount of fuel passing through the supply line it is determined by flow restrictors in the supply line branches 11A and 1B. The supply line branch 1A contains a variable flow restrictor 20, the flow resistance of which is controlled in response to engine loading (as determined, for example, by engine inlet manifold vacuum or engine throttle opening) to increase the fuel flow as the engine load increases. Whilst this control is effective to meter an adequate fuel flow to the injector devices at engine speeds above the engine idling speed range, the engine can be starved of fuel supply when the engine is idling with the variable restrictor 20 closed due to the negligible engine load. If, at engine idling speeds, the restrictor 2th is arranged to be open sufficiently to ensure adequate fuel supply to the injector devices, then at increased cngine loads excess fuel is supplied to the injector devices, which is undesirable. The problem is solved in the system shown in FIG. 1 by provision of a fixed restrictor 21 in the branch 1B of the supply line 1 at a location upstream of the connection of the branch to the restrictor 6B, and a valve member 22 engageable with a seating 23 disposed downstream of the connection of the branch 18 to the restrictor 8B. The valve member 22 is urged towards an unseated position by a light spring 24 and is carried by a plunger 25 exposed to fuel pressure in the supply line branch llB upstream of the restrictor 21. At engine idling speeds, and low operating speeds when the variable restrictor 20 is closed or only slightly open, the spring 24 is arranged to prevent the valve member 22 being seated by fuel pressure in the branch 1B (which is dependent on engine speed) acting on the plunger 25. Thus, fuel can flow via restrictor 21 past a non-return valve 26 to the distribution chamber 4- and hence to the injector devices 7, the restrictor 21 offering a flow resistance such that there is adequate fuel flow to the injectors under these engine operating conditions.

As the engine speed increases, the unseating force for the spring 24 is overcome by the fuel pressure in the branch llB acting on the plunger 25 so that any fuel flow through the restrictor 21 passes via restrictor SE to the bypass line 9. Fuel flow to the injector devices then is solely via the variable restrictor 20 in the branch 1A, the flow resistance of which decreases with increasing engine load. Thus, fuel supply to the engine is metered by adjustment of fuel supply pressure in dependence on engine speed and adjustment of fuel flow in dependence on engine loading.

Under engine overrun conditions, i.e. high engine speed and engine throttle closed (corresponding to negligible engine loading and high inlet manifold vacuum), the variable restrictor 249 is closed and the valve member 22 is seated so that the injector devices receive no fuel supply, which is the desired condition.

The injector devices 7 each have a housing 110 from which projects a tube 111 at the end of which is an outlet orifice 112. A resilient diaphragm 113 divides the housing into two chambers 114 and 115, the former communicating with a feed line 5 and with the tube 111 and the latter containing a light spring 116 bearing on the diaphragm and urging a. valve member 117 carried by the diaphragm towards a seated position in the outlet orifice 112. The arrangement is designed such that inlet manifold vacuum does not interfere with fuel flow to the injector devices, particularly under conditions of low engine speed (i.e. low fuel pressure) and high inlet manifold vacuum (e.g. engine idling condition), the nozzles of the injector devices being disposed in the inlet manifold downstream of the throttle valve. Under these conditions fuel flow through to injector outlet orifice 112 might be such that the chamber 114 became exposed to inlet manifold vacuum which would interfere with fuel flow to the injector devices. However, when fuel flow falls to such a level, the spring H6 seats the needle 117 in the outlet orifice until fuel pressure in the chamber 114 acting on diaphragm 113 is sufiicient to unseat the needle 117.

Instead of connecting the

lines

2A and 23 to a common chamber 3 which in turn is connected to a distribution chamber 4, each of the

lines

2A and 23 could be connected to

separate distribution chambers

30 and 31 as shown in FIG. 2. From the chamber 3%, lines 32 containing non-return valves 33 communicate with the feed lines 5 to individual injector devices 7, the feed lines 5 containing flow restrictors 6. The chamber 31 also communicates via lines 34 containing flow restrictors 35 with the feed lines 5 to the individual injector devices '7, the points of connection being upstream of the restrictors 6.

FIG. 3 shows, in section, a control assembly containing the flow control components in the supply line branches 3A and 1B. The assembly has a housing 40 having a cylindrical chamber 41 containing the variable restrictor 20. The restrictor includes a sleeve 42 having an aperture 43. Rotatably disposed in the sleeve is a closely fitting valve member 4 having a passage 45 extending partly along its length from one end thereof. An elongated transverse slot 46, having outwardly divergent walls which, projected, define a V-section, is formed in the wall of the valve member and communicates with the passage 45 and the aperture 43 in the sleeve. A passage 47 leads from the aperture 4-3 to a first outlet port 48.

A fuel inlet port 49 communicates via a passage 50 with the chamber 41 and the open end of the valve member 44. A passage 51 leads from the passage So to a chamber 52 which communicates via a small bore passage 53 (forming the fixed restrictor ,1) in the closed end of plunger 25 with the interior of the plunger. The plunger 25 carries the valve member 22 engageable with the seating 23 which is provided at one end of chamber 52. The spring 24, biases the plunger 25 to an unseated position. A passage communicating with the bore of the seating 23 downstream of the non-return valve 26 leads to a second outlet port 54 whilst a passage 55 leads to a return flow port, not shown.

In use of this control assembly in the system shown in FIG. 1, the inlet port 49 is connected to the supply line 1, the passages 50 and 51 forming the inlet sections of branches 1A and 1B. The first outlet port 48 is connected to line 2A and to restrictor 8A, the second outlet port 54 to the line 213 and the return flow port (not shown) to which the passage 55 leads is connected to the restrictor 8B.

The valve member 44 of the variable restrictor 21 shown in FIG. 3 extends, at its closed end, into a chamber 56 and is coupled by an arm 57 to a roller 58 engaged by a cam 59 carried by a shaft 60 for rotation therewith. The shaft 60 can be coupled to the engine throttle operating mechanism so that as the throttle is opened, the cam 59 is rotated, the valve member 44 also being rotated in a manner dependent on the cam surface of cam 59. As the valve member 44 rotates, the area of the V-slot 46 is registration with the aperture 43 increases thereby increasing fuel flow to the port 48 as the throttle opening increases.

Instead of being coupled to the engine throttle opening mechanism by the shaft 60, the cam 59 could be coupled to a plunger movable to rotate the cam in response to engine inlet manifold vacuum so that decreasing manifold vacuum causes increase in the fuel flow through the outlet port 48.

The system illustrated in FIG. 4 differs from that shown in FIG. 1 in two main respects. Firstly, the branch of the supply line 1 of the system shown in FIG. 4 includes a fixed fiow restrictor 71 for each nozzle. In place of the variable flow restrictor shown in FIG. 1, the system shown in FIG. 4 has a variable flow restrictor 73 connected in the supply line 1 upstream of the branches 1A and 1B. The variable flow restrictor 73 can be of similar construction and operated in like manner to the restrictor 20 shown in FIG. 3. Alternatively, it can be constructed in the manner disclosed in respect of the metering valve shown in co-pending application No. 8,528/ 65. The second difference of the system shown in FIG. 4 as compared with that shown in FIG. 1, is that the fuel flow in the supply line 1 has, under normal engine operating conditions, a minimum pressure determined by a diaphragm valve 74 connected in the supply line branch 1A whilst fuel flow through the by-pass line 9 has a like minimum pressure determined by the relief valve 16.

The branches 1A and 1B are connected to distribution chambers 4A and 4B to which the injector devices 7 are connected by respective flow lines 5 containing flow restrictors 6, in the manner described with reference to FIG. 1. A check valve in each connection to flow lines 5 prevents return fiow to chamber 4A. The standing fuel pressure introduced by the diaphragm valve 74 is sutficient to prevent fuel vaporisation upstream of the diaphragm valve 74 during all operating conditions and speeds of the engine. Downstream of the diaphragm valve 74, in the flow paths to the injector devices, the standing pressure is not present but is re-introduced in the by-pass line 9 by the relief valve 16.

During engine operation at idling speeds when the fuel pressure in the supply branch 1, determined by the engine driven pump 10, is less than that necessary to open the diaphragm valve 74, fuel passes to the injector devices 7 through supply line branch 1B. This branch contains a diaphragm valve 75 that is opened at a fuel pressure sufficiently lower than that required to open the diaphragm valve 74, to ensure an adequate fuel supply to the injector devices under engine idling conditions, when the variable restrictor 73 in only partly open. Fuel flow through the diaphragm valve 75 passes to chamber 4B and through the restrictors 71 to the injector feed lines 5.

As the engine speed increases above the idling speed range, the diaphragm valve 74 opens and fuel fiows through both branches 1A and IE to the injector devices until the back pressure across the restrictor 71 (which has a higher flow resistance than that of restrictor 6) reduces fuel flow through the branch IE to a negligible value or to zero.

FIGS. 58 show a control assembly 80 containing the diaphragm valves 74 and 75 and the flow restrictor 71. The control assembly 80 has an inlet port 79 leading via passages 81 and 81' (forming parts of branches 1A and 1B respectively) to annular chambers 82 and 82' forming parts of the diagragm valves 74 and 75 respectively. The chambers 82 and 82' are separated from

distribution chambers

30 and 31 by

resilient diaphragms

83 and 83 urged by springs 84 (adjustable by screws 85) towards seated positions on annular walls 86, 86', projecting into the

chambers

82, 82, respectively, to define

chambers

87 and 87. The diaphragms 83 and 83' have central apertures 88 and 88' so that when the diaphragms are unseated, fuel can flow from the chambers 82 and 82' via

chambers

87 and 87 and the apertures 88 and 88' in the fit 6

diaphragms

83 and 83 into the distribution chambers 30 and 30'.

The distribution chamber 30 communicates via a passage with a chamber 89 from which lead individual passages 90, each containing a non-return valve 91, to ports 92 (to which the lines 5 are connected). The distributor chamber 31 communicates 'via passages 94, each containing a restrictor in the form of a long fine tube 95, to the ports 92 into which the tubes 95 extend.

Downstream of the

passages

81 and 81, the inlet port 79 communicates with a chamber 96 containing an orifice disc 97 and an adjustable flow restrictor 98. The restrictor 98 extends through the orifice disc 97 and has a portion 99, the transverse cross-section of which varies along the length of the restrictor. The flow restriction presented by the orifice thus depends on the position of the variable area portion 99 relative to the disc 97 which position can be adjusted by a screw 100, against which the restrictor 98 is held by a spring 101. An outlet port 102 leads from the chamber 96, downstream of the orifice disc 97, and in use of the assembly is connected to the by-pass line 9 in FIG. 4, the variable area orifice disc 97 forming the flow restrictor 8.

I claim:

1. A continuous fuel injection system for an internal combustion engine, comprising in combination:

(A) a fuel circulation path including a fuel supply conduit and a fuel return conduit, the fuel supply conduit having first and second parallel flow branches,

(B) feed conduits connecting said first and second branches directly to each one of a plurality of fuel injector devices each having a fuel outlet orifice,

(C) a respective fixed flow equalising restrictor in each of the fuel flow paths defined by the said feed conduits and the injector devices the said fuel return conduit being connected to said first branch downstream of the connection of said first branch to the injector devices and being connected to said second branch upstream of the connection of said second branch to the injector devices,

(D) an engine driven fuel pressurising device con nected in said fuel supply conduit upstream of said first and second branches and operable to increase fuel pressure with increasing engine speed,

(E) a reference fixed flow restrictor in the said second branch upstream of the connection to the said return conduit,

(F) a fuel pressure-responsive valve device in said second branch downstream of the connection to the return conduit and means biasing said fuel pressure-responsive valve device to an open position, said fuel pressure-responsive valve device being exposed to the fuel pressure drop across said reference restrictor in the second branch to close the second branch in response to a fuel pressure drop corresponding to engine speeds greater than a predetermined value, and

(G) engine load responsive fuel flow control valve means connected in said supply conduit downstream of said fuel pressurising device for supplying fuel to the injector devices via said first branch in dependence on engine loading at least at engine speeds greater than the said predetermined value.

2. A system according to claim 1, wherein said fuel flow control valve means is connected in the said first branch of the supply conduit for supplying fuel to the injector devices in dependence on engine loading at substantially all engine speeds.

3. A system according to claim 2, wherein said fuel flow control valve means includes a rotary valve member and engine load responsive means coupled to said valve member for rotating said valve member to increasingly open said first branch with increasing engine loading, and wherein said fuel flow control valve means and said fuel pressure-responsive valve device are contained in a common housing, a first passage in said housing defining the first branch of the supply conduit and containing the rotary valve member, a second passage in said housing defining the second branch of the supply conduit and communicating with the first passage upstream of the rotary valve member, said second passage including a chamber defining a valve seating, a closure valve member engageable with said seating to close said second passage and means resiliently biasing said closure valve member towards an unseated position, a plunger in said chamber carrying said closure valve member, and a passageway extending through the plunger defining the said reference fixed flow restrictor in the second branch whereby the pressure differential due to fuel flow through said passageway urges said plunger to move the closure valve member towards a seated position against said resilient bias.

4. A continuous fuel injection system for an internal combustion engine, comprising in combination:

(A) a fuel circulation path including a fuel supply conduit and a fuel return conduit, the said supply conudit having first and second parallel flow branches,

(B) feed conduits conecting said first and second branches directly to each one of a plurality of fuel injector devices,

(C) a respective fixed flow equalising restrictor in each of the fuel flow paths defined by the said feed conduits and the injector devices, the said fuel return conduit being connected to said first branch downstream of the connection of said first branch to the injector devices,

(D) an engine driven fuel pressurising device connected in said fuel supply conduit upstream of said first and second branches and operable to increase fuel pressure with increasing engine speed,

(E) a low fuel-pressure-responsive valve device in said second branch and means biasing said low fuelpressure-responsive valve device to a closed position, fuel pressure in the second branch at engine speeds less than a predetermined value acting on said low fuel-pressure responsive valve device to open said second branch and permit passage of fuel to the injector devices,

(F) a reference fixed flow restrictor in the second branch downstream of the low fuel-pressure-respont3 sive valve device, the downstream end of said reference flow restrictor being connected to said first branch downstream of the connection of the branch to said return conduit, and (G) engine load responsive fuel flow control valve means connected in said supply conduit downstream of said fuel pressurising device for supplying fuel to the injector devices via said first branch in dependence on engine loading at least at engine speeds greater than the said predetermined value, the said reference flow restrictor in said second branch having flow resistance such that pressure in said second branch upstream of said low fuel-pressure-responsive device acts on said low fuel-pressure-responsive device at engine speeds greater than the said predetermined value to close said second branch. 5. A system according to claim 4, wherein said flow control valve means is connected in the supply conduit upstream of the first and second branches for supplying fuel to said first and second branches in dependence on engine loading at substantially all engine speeds, and including a high fuel-pressure-responsive valve device in said first branch and means biasing said high pressureresponsive valve device to a closed position, fuel pressure in said first branch at engine speeds greater than the said predetermined value acting on said high fuel-pressure-responsive valve device to open the first branch and permit passage of fuel to the injector devices.

References Cited UNITED STATES PATENTS 2,656,848 10/1953 Noon et a1 123-119 XR 2,924,206 2/1960 Groves 123-43917 2,940,435 6/1960 Nemec et al. 123139 3,019,603 2/1962 Kreutzer 39.28 3,036,564 5/1962 Guiot 123140.3 3,285,233 11/1966 Jackson 123139.17 3,330,300 7/1967 Jackson 137614.14

LAURENCE M. GOODRIDGE, Primary Examiner.

US. Cl. X.R. 123119, 140