US3386428A

US3386428A - Engine fuel supply system

Info

Publication number: US3386428A
Authority: US
Inventors: Martin W Slabey; Wu Tao-Yuan
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1966-04-20
Filing date: 1966-04-20
Publication date: 1968-06-04
Anticipated expiration: 1985-06-04

Description

June 4, 1968 M. SLABEY ETAL ENGINE FUEL SUPPLY SYSTEM 2 Sheets-Sheet 1 Filed April 20, 1966 5 I MART/N W SLABEY RIO-YUAN WU INVENTORS Q45 Fw yw/wm F /GA ATTORNEYS June 4, 1968 M. w. SLABEY ETAL 3,386,428

ENGINE FUEL SUPPLY SYSTEM Filed April 20, 1966 2 SheetS Sheet 2 M4,? TIN W SLABEY 7710-YLMN WU INVENTORS United States Patent M 3,386,428 ENGINE FUEL SUPPLY SYSTEM Martin W. Slabey, Dearborn, and Tao-Yuan Wu, Ann Arbor, Mich., assignors to Ford Motor Company, Dearborn, Mich, a corporation of Delaware Filed Apr. 20, 1966, Ser. No. 543,898 11 Claims. (Cl. 123-139) ABSTRACT OF THE DESCLOSURE A bypass valve is used in the fuel supply system for a fuel injection engine to divide bypass fuel flow into primary and secondary channels. A plurality of orifices are movable individually into the primary channel to adapt the fuel supply system to different types of fuel or different types of general engine operation. The secondary channel contains a valve linked to the throttle blade to open when the throttle blade closes, thereby permitting extra fuel bypass during engine deceleration. A pressure responsive valve is located in the secondary channel to prevent fiow through the secondary channel at low speeds so high injection pressures are available for acceleration. In addition, a valve for stopping all flow through the bypass system, which is desirable for starting, is included in the bypass valve housing.

This invention provides a fuel supply system for an internal ombustion engine that accurately matches the quantity of fuel supplied to the engine requirements. This invention is useful particularly in fuel injection engines used for ordinary driving, racing, or both ordinary driving and racing.

The amount of fuel supplied to the combustion chambers of a fuel injection engine depends on the fuel pressure drop through the injection nozzles, called the injection pressure. For ordinary road load operation the fuel quantity required by the engine is proportional to engine speed, but the fuel quantity required for accelerating at any engine speed or operating near wide open throttle is much greater than the proportionate amount, while the quantity required when decelerating is much less.

Engine driven, positive displacement fuel pumps supply fuel at a rate proportional to engine speed and independent of fuel pressure and are used widely in fuel injection fuel supply systems because of these characteristics. At any engine speed, the fuel pump must supply a pressure sufficiently high to provide an accelerating injection pressure when acceleration is desired. These already high pressures can become extremely high when decelerating the engine, since the amount of fuel required by the engine is low while the pump speed is high. Means are required in the fuel supply system of fuel injection engines to prevent the high accelerating pressures from being applied to the injection nozzles when acceleration is not desired and to prevent the fuel pump from developing extremely high fuel pressures when the engine is decelerating.

In most of the current production engines used for ordinary city and highway driving Where engine speed ranges up to about 4500 r.p.m., the injection pressure for road load operation is provided by interposing a variable restriction in the fuel supply circuit capable of reducing fuel line pressure to the proper injection pressure. The restriction is reduced by the accelerator linkage when acceleration is desired and is calibrated to provide the proper mixture for idling and full power operation. A bypass circuit having a pressure relief valve therein bypasses fuel when fuel line pressure builds up during decelera- 3,386,428 Patented June 4, 1968 tion. However, a racing engine operates at much greater speeds, in some cases exceeding 9000 rpm. The faster accelerating rates demanded of racing engines require increased accelerating injection pressures and the wide variations in engine speeds render simple restrictions and bypass circuits ineffectual in controlling fuel line pressure to the proper injection pressure under one set of operating conditions Without affecting adversely the injection pressure at other speeds.

Difliculties arise in racing engines, for example, when accidents occurring during a race require the cars to operate at a moderate speed for several laps. Most prior fuel systems supply an excessively rich fuel mixture to the engine under these moderate speed conditions, thereby fouling engine parts and unnecessarily increasing the fuel consumed by the engine. In addition, may racing drivers desire a different type of fuel for different driving conditions. For example, some drivers use one fuel blend for qualifying and switch to another fuel blend for the actual race. The flow characteristics of each fuel blend must be matched to engine requirements which, in the past, has required changing and adjusting fuel pumps, injection nozzles, accelerator linkage, and other elements of the fuel supply system.

Fuel flow characteristics of the fuel supply system of this invention can be changed rapidly by the driver to accommodate changes in engine operation and in the flow characteristics of a variety of fuel blends by a relatively simple operation that does not require changing parts or adjusting linkages. In addition to the many advantages provided by the fuel supply system of this invention in racing engines, the system also improves the fuel economy of engines used in ordinary driving by more closely matching injection pressure to engine speed. This fuel supply system has a fuel bypass circuit that establishes proper fuel line pressure by providing means for dividing the fuel flow through the bypass circuit into primary and secondary channels. A flow constriction means is positioned in the primary channel and a throttle valve and a pressure relief valve are positioned in the secondary channel. The throttle valve is connected to the engine accelerator linkage and adjusts the bypass fuel fiow through the secondary channel according to the throttle position. The pressure relief valve maintains minimum fuel line pressure at moderate engine speeds. A standard metering block adjusts the fuel line pressure to the proper injection pressure.

A shutoff valve preventing flow through the bypass circuit at extremely low engine speeds encountered, for example, when starting the engine, can be included in the system of this invention if desired. By changing the flow constriction means the fuel supply system is readily tailored for the expected type of sustained engine operation such as city driving, highway driving, part throttle racing, or wide-open throttle pacing, or operation on a different fuel blend.

For convenience, the entire fue'l bypass circuit of this invention can be included in a single control valve. In this valve the flow constriction means comprises a rotatable member having a plunality of orifices individually movable into the primary channel. Other features and advantages provided by the fuel system of this invention are included in the following detailed description of the drawings in which:

FIGURE 1 is :a schematic diagram of the fuel system of this invention for a fuel injection engine showing the fuel bypass circuit enclosed by a dotted line;

FIGURE 2 is an end vie-w of a control valve perfor the functions of the devices shown within the dotted line in FIGURE 1;

FIGURE 3 is a side sectional view along line 3-3 of 3 FIGURE 2 showing the shutoff valve and the How constriction means in the primary channel of the control valve;

FIGURE 4 is a top sectional view along line 44 in FIGURE 2 showing the shutoff valve, the plurality of orifices of the flow constriction means in the primary channel, and the throttle valve and the pressure relief valve in the secondary channel; and

FIGURE 5 is an end sectional view taken through the control valve of the location of line 5-5 of FIGURE 4.

Referring to the fuel injection system shown schematically in FIGURE 1, a gear-type fuel pump 16 driven by the engine by conventional means (not shown) pumps fuel from a fuel tank 12 into a high pressure fuel line 14. High pressure line 1 branches into a bypass branch 16 and an engine supply branch 18. Engine supply branch 18 passes through fuel metering block 20 and fuel distributing lines 22 to the fuel distributor blocks 23 that distribute fuel to the fuel injection nozzles 24. Bypass branch 16 enters the control valve indicated generally by the dotted line 28, and return line 44 located between the outlet of control valve 28 and fuel tank 12 completes the bypass circuit.

The engine air intake passage 46 is also shown schematically in FIGURE 1. Mounted in air intake passage 46 is a movable blade 43 that is attached to a lever 59. Linkage 52 connects lever 50 with a lever 56 controlling fuel flow through metering block 29. Conventional means (not shown) connect linkage 52 to a conventional accelerator pedal (not shown).

Bypass branch 16 enters the control valve 28 at its inlet 26. Within valve 28 bypass fuel initially passes through a shutoff valve 30 and then is divided into primary and secondary channels 32 and 34, respectively. A flow constriction means 36 is positioned in the primary channel 32, and a throttle valve 38 and a pressure relief valve 40 are positioned in series in the secondary channel 34. A lever 54 connects throttle valve 38 with linkage 52. Fuel flow through the primary channel 32 is recombined with fuel flowing through secondary channel 34 just prior to the valve outlet 42. The recombined bypass fuel returns to fuel tank 12 via return fuel line 44.

Shown in FIGURE 2 is a typical control valve 28. Valve 28 comprises a valve body 58 having lever 54 pivotally mounted at one end adjacent valve inlet 26. Lever 54 is attached to a shaft 116- that controls flow through the throttle valve 38 in a manner shown in more detail in FIGURE 4. Projecting from the top of valve body 58 is a shaft 60 that controls flow through flow constriction means 36.

As shown in FIGURE 3, the section of valve body 58 through inlet 26 and shaft 60 is L-shaped. An enlarged bore 64- is drilled into the long leg of valve body 53, and an inlet fitting 62 forming inlet 26 is threaded into the end of bore 64. A cone-shaped valve member 66 slides on a plurality of vanes 68 in bore 64. The base 63 of inlet fitting 62 serves as the valve seat for valve member 66. A spring 70 urges valve 66 toward its seat and an O-ring seal 72 seals the connection between valve body 58 and inlet fitting 62. Spring 70, valve member 66 and base 63 form the shutoff valve 31 of the FIGURE 1 schematic.

Behind valve member 66 a first passage 74 coaxial with bore 64 and a second passage 76 perpendicular to bore 64 are drilled into body 53. Passage 74 opens into an enlarged bore 78 formed in the short leg of valve body 58 perpendicular to the axis of bore 64. A sleeve bushing 80 having a hole 81 communicating with passage 74 is pressed into the upper end of bore 78. Passage 74 and hole 81 constitute a portion of primary channel 32. Rotatably mounted in sleeve bushing 80 is a cylindrical member 82 which serves as the flow constriction means 36.

Cylindrical member 82 has a radial hole 33 therein aligned at one end with hole 81 when member 82 is positioned as shown. Hole 83 communicates with a bore 84 within and parallel to the axis of member 82. Threadably mounted in the lower portion of bore 84- is an orifice body 86 having an orifice 88 therein. Shaft 60 projecting through the top of valve body 58 is formed integrally with cylindrical member 82 and is positioned at the top thereof. An O-ring seal 90 surrounds shaft 60 to seal the surface between shaft 66 and body 58.

On the side of cylindrical member 82 opposite bore 84 a short detent hole 92 is drilled into member 82. A hole is drilled through valve body 58 adjacent detent hole 92, and a detent ball M is spring uoaded by spring 96 into detent hole 92. Spring 96 seats on a plate 98 attached to valve body 58 by threaded fasteners 160.

An outlet fitting 192 forming outlet 42 is threaded into the lower part of bore 73 and is sealed therein by an O ring 104. A spring 1116 seats on outlet fitting 102 and holds cylindrical member 82 in position in the upper end of bore 78.

Referring to FIGURE 4, the second passage 76 is drilled through an inner wall of valve body 58 into another bore 163 that is parallel to bore 64 but opens at the opposite end of valve body 5c. The access hole in the outer wall of body 58 necessary for drilling passage 76 through the inner wall is closed by a plug 110. A sleeve bushing 112 having a hole 113 therein communicating with passage '76 is pressed into the far end of bore 108. Passage 76 and hole 113 constitute a portion of secondary channel 34.

A cylindrical member 114 having a concentric hole 115 in one end and an opening 117 in the shape of a slot in one side communicating with hole 115 is rotatably positioned in the far end of bushing 112. Shaft 116 is formed integral-1y with member 114 and extends through valve body 58. An O-ring 118 seals the surface between shaft 116 and body 58 and the throttle valve lever 54 is attached to shaft 116 outside of valve body 58. A variable area of slot 117 is aligned with hole 113 during rotation of member 114 in bushing 112 to form throttle valve 33 of the FIGURE 1 schematic.

A cone-shaped valve member is slidably mounted in the near end of bus-hing 112 and is urged toward hole 115 in member 114 by spring 122. Valve member 120 seats on the base 119 of member 114 surrounding hole 15. Spring 22 seats in a plug 124 threaded into the open end of bore 103 and sealed therein by O-ring 126. Valve 120 is positioned in bushing 112 by vanes 121 similar to the vanes 68 on valve 66 and shown in more detail in FIG- URE 5. Spring 122, valve member 120 and base 119 form the pressure relief valve 40 of the FIGURE 1 schematic.

FIGURE 4 shows additional

orifice containing bores

128 and 130 and corresponding detent holes 132 and 134 in member 82.

Bores

128 and 130 communicate with

holes

129 and 131, respectively, opening on a narrow segment of cylindrical member 82 on either side of the hole 83 to that minimal rotation of member 82 is required to align one of the bores with hole 81.

Orifice 88 and corresponding orifices in bores 128 and 134) are selected to provide the fuel fiow characteristics through the bypass circuit that produce the proper fuel line pressure for the expected driving conditions. For example, the control valve for an engine used for ordinary driving has only two orifices; one for city driving and a second for highway driving. For a racing engine, the typical control valve has one orifice for the qualifying fuel blend, a second orifice for maximum power operation on a racing fuel blend, and a third orifice for maximum economy operation on the racing fuel blend. Where the same fuel is used for qualifying and racing, an orifice compensating for pump wear or temperature or barometric pressure changes can be provided in place of the qualifying orifice.

As shown in FIGURE 5, a passage 136 is drilled from bore 78 below bushing 81 angularly upward through bushing 112, opening into bore 108 behind valve member 120. Passage 136 serves as the portion of the secondary channel 34 transmitting fuel from relief valve 40 to outlet 42.

OPERATION At engine cranking speeds, fuel line pressure in

lines

14, 16 and 18 is insufficient to unseat shutoff valve member 66, and the fuel from pump is metered by metering block 20 to distributor blocks 23 where the fuel is distributed to the nozzles 24. Two distributor blocks 23 and eight nozzles 24 are shown to exemplify a typical racing engine. Metering block 20 adjusts fuel line pressure to the proper injection pressure and proportions fuel flow through nozzles 24 to the air flow through air intake passage 46 in a conventional manner.

When the engine is running, pump 10 typically pumps considerably more fuel than the engine requires, and the increase in fuel line pressure unseats shutoff valve member 66, thereby opening shutoff valve 30.

Lever 54 positions member 114 so the area of slot 117 aligned with hole 113 is indirectly related to the amount of the throttle opening and becomes zero at wideopen throttle or at some point below wide-open throttle, thereby closing oil the secondary channel. At engine speeds below a certain preselected 'r.p.m., pressure relief valve member 120 remains seated on base 119'of cylindrical member 114 so all of the bypass fuel flows through the primary channel. The orifice aligned in the primary channel provides a sufiicient restriction to the fuel flow to establish the minimum operating pressure. Shutoff valve 30 is ineffectual for this purpose because it must unseat at a much lower pressure. When engine speed is above the point at which the fuel pressure exceeds the preselected opening pressure for unseating pressure relief valve member 120, additional bypass fuel is permitted to flow through secondary channel 34.

When acceleration of the engine is desired, ordinary movement of the accelerator pedal not only opens metering block 20 to increase the injection pressure but also increases the restriction provided by valve 38 to the bypass fuel flow to increase the fuel line pressure.

For a race where full power output at wide-open throttle is required repeatedly, a medium-size orifice located, for example, in bore 34 is positioned in the primary channel. Member 114 usually is set to close secondary channel 34 at a relatively low throttle opening for such a .race to provide the high fuel line pressures desired for maximum power output. During the short periods of deceleration, such as when entering a curve, engine speed is high and the fuel required is low. A fuel pressure buildup during this deceleration is avoided by lever 54 positioning member 114 to open secondary channel 34 so the excess fuel can flow through the secondary channel.

If the racing car is required to slow down for an extended period of time, such as when the caution flag is being displayed on the race track, fuel flow through the secondary channel becomes insufficient to relieve the fuel line pressure building up on the pressure side of pump 10. Ordinarily, this increased pressure would enrich unnecessarily the fuel-air ratio of the mixture supplied to the engine, thereby decreasing the fuel economy, and also causes unnecessarily rich injection pressures for acceleration. However, with the fuel system of this invention the driver of the auto can prevent such enrichment by rotating member 82 so a larger orifice positioned, for example, in bore 130 is located in the primary channel. Additional fuel flowing through the larger orifice relieves the fuel line pressure buildup, thereby preventing excessively rich engine operation during the caution period.

Opening and closing .pressures of

valves

30 and 40, the relationship of valve 38 to the opening of throttle blade 48, and the sizes of the orifices in flow constriction means 36 depend on the flow characteristics of the systerm and the fuel requirements of the engine and usually are determined by empirical tests. If desired, a continuously variable flow constriction means 36 and an abruptly opening valve 38 can be used.

Thus, this invention provides a fuel supply system for a fuel injection engine that increases both the operating economy and the performance of the engine by tailoring the injection pressure to the engine requirements with greater accuracy than prior art fuel supply systems. In addition, the system is readily modified to permit the engine to operate on a different type of fuel, a particularly important feature in racing engines.

It is emphasized that the invention is not limited to the exact constructions shown or described but that changes and modifications can be made Without departing from the spirit and scope of the invention as defined in the claims.

We claim:

1. In a fuel supply system for an internal combustion engine, a fuel bypass circuit comprising a control valve, said control valve comprising a valve body,

means for dividing fuel flow through said valve body into primary and secondary channels,

a flow constriction means positioned in said primary channel in said valve body, said flow constriction means comprising a member having a plurality of orifices therein, said member being movable manually to individually position each of said orifices in said primary channel,

a throttle valve positioned in the secondary channel in said valve body and connected to the engine accelerator linkage, and

a pressure relief valve positioned in one of the channels in said valve body.

2. The bypass circuit of claim 1 in which said pressure relief valve is positioned in the secondary channel in the valve body.

3. The bypass circuit of claim 2 in which the throttle valve comprises a cylindrical member having a hole in one end and an opening in the side communicating with said hole, said hole and opening being part of the secondary channel, said cylindrical member being rotatable in the body to align various amounts of said opening with the secondary channel.

4. The bypass circuit of claim 3 in which the end of the cylindrical member is the valve seat for the pressure relief valve, said pressure relief valve being spring loaded toward said seat.

5. The bypass circuit of claim 4 in which the control valve comprises a shutoff valve mounted in said valve body for stopping fluid flow through said control valve when fluid pressure is below a predetermined value.

6. The bypass circuit of claim 1 comprising a shutoff valve for stopping flow through said circuit when fuel pressure is below a predetermined value.

7. A fuel supply system for an internal combustion engine comprising:

a fuel pump pumping fuel from a fuel tank into a fuel line to produce fuel line pressure,

metering means transporting fuel from said fuel line to a fuel injection nozzle, said metering means reducing said fuel line pressure to fuel injection pres sure,

a fuel bypass circuit having means for dividing fuel flow into primary and secondary channels, a flow constriction means positioned in said primary channel, said flow constriction means comprising a member having a plurality of orifices individually positionable in said primary channel, and a throttle valve positioned in said secondary channel, and

means linking said metering means with said throttle valve.

8. The fuel supply system of claim 7 in which the bypass circuit comprises shutoff valve means preventing fuel flow through said bypass circuit when fuel line pressure is below a preselected value.

9. The fuel supply system of claim 8 in which a pressure relief means positioned in the secondary channel prevents fuel flow through said secondary channel when fuel line pressure is below a preselected value.

10. The fuel supply system of claim 9 in which a control valve has the means for dividing fuel flow, the flow constriction means and the throttle valve located therein.

11. The fuel supply system of claim 10 in which the shutoff valve means and the pressure relief means are located in the control valve.

References Cited UNITED STATES PATENTS Winfield 123139.17 Plattner et al. 123-139.17

Groves 123-119 Tuscher.

Powell et a1 123-43917 Groves.

Powell et a1 123-13917 Groves.

Wallman Jr. 123-419 Guiot.

Dolza.

LAURENCE M. GOODRIDGE, Primary Examiner.