US3673996A

US3673996A - Fuel injection pump timing and metering arrangement

Info

Publication number: US3673996A
Application number: US77407A
Authority: US
Inventors: Alexander Dreisin
Original assignee: Allis Chalmers Corp
Current assignee: Deutz Allis Corp
Priority date: 1970-10-02
Filing date: 1970-10-02
Publication date: 1972-07-04
Anticipated expiration: 1989-07-04
Also published as: CA947595A; JPS5238169B1

Abstract

A fuel injection pump for an internal combustion engine having a control sleeve operated by separate metering and timing control elements.

Description

O United States Patent [151 3,673,996 Dreisin 1 July 4, 1972 [54] FUEL INJECTION PUMP TIMING AND 2,746,443 5/1956 Meyer ..123/139 BD METERING ARRANGEMENT 2,772,668 12/1956 Nyslrom... ..l23/139 BD r 2,778,351 l/1957 Links ..l23/l39 BD [72] Inventor. Alexander Dreism, Olymp1a F1elds,lll. 2,813,523 11/1957 Bischoff 123/139 BD [73] Assignee: Allis-Chalmers Manufacturing Company, 2,980,092 4/1961 Dreisin ..l23/l 39 BD Milwaukee, Wis.

FOREIGN PATENTS OR APPLICATIONS [22] Filed: Oct. 2, 1970 697,542 9/1953 Great Britain ..l23/l39 [21] App1.No.: 77,407

Primary Examiner-Laurence M. Goodridge 52 11.5.01. ..123/139 AP, 123/139 BD, 123/139 AB, Assistant COX 123/139 AC 123/139 AR, 123 139 AD, 123 139 Att0rney-Arthur L. Nelson, Robert B. Benson and Charles L.

AE Schwab [51] Int. Cl ..F02m 39/00 [58] Field of Search ..l23/l 39 R, 139 BD, 139 AP ABSTRACT References Cited A fuel injection pump for an internal combustion engine haw ing a control sleeve operated by separate metering and timing UNITED STATES PATENTS control elements- 2,624,327 l/1953 Hogeman ..l23/139 BD 10 Claims, 13 Drawing Figures FUEL INJECTION PUMP TIMING AND METERING ARRANGEMENT This invention relates to a fuel injection pump and more particularly to means providing individual metering and timing control levers to operate the control sleeve whereby movement of one lever effects a control without changing the effect of the other control lever.

Distributor type fuel injection pumps of the type which utilize a reciprocating plunger which reciprocates within the pump housing usually in response to a cam action while simultaneously being rotated for selective communication with delivery passages to the engine, normally use a control sleeve to sequentially close and open communication between a fuel supply chamber and a high pressure injection chamber. The closing of a port initiates fuel injection while opening of the port permits the spill of pressurized fluid to terminate fuel injection.

The conventional control mechanism for the control sleeve raises or lowers the control sleeve on the plunger whereby lowering of the sleeve advances timing of fuel injection while the raising of the sleeve retards the timing of fuel injection. A rotation of the control sleeve controls the quantity of fuel injected by metering the quantity of fuel to each combustion chamber. Generally, controlling of timing and quantity of fuel is through a single rod. The timing control varies either the start or the end of fuel injection and in the conventional fuel injector this also varies the effective stroke. This has disadvantageous effects since it is not necessarily desirable to increase the quantity of fuel with an advance in the timing of the fuel injection and accordingly this invention provides a means whereby the timing is completely independent of the quality of fuel injection. This is accomplished by using axial grooves on the inner periphery of the control sleeve which will spill pressurized fluid on termination of fuel injection. The port on the plunger sequentially communicates with the spill groove. The path of the spill port of the plunger defines a wavy curve due to the rise and fall of the cam follower reciprocating the plunger while the plunger is simultaneously rotated. The constant velocity portion of the curve defines an angle on the inner periphery of the control sleeve. If the slot receiving an element of the quantity control linkage positioned on the external periphery of the control sleeve is positioned at a properly selected angle, the effective length of the pumping stroke of the plunger can be kept constant for any retardation or advance of the fuel injection cycle.

Accordingly it is an object of this invention to provide a fuel injection pump having separate metering and timing control elements connected to the control sleeve.

It is another object of this invention to provide a fuel injection pump having a control sleeve to control the timing and metering with individual levers connected to the control sleeve through control slots on the external periphery on the control sleeve.

It is a further object of this invention to provide a distributor type fuel injection pump having a control sleeve receiving a pumping plunger whereby the outer perimetry of the control sleeve fonns a horizontal slot to receive a timing control element and an inclined slot to receive a quantity control element, the angle being such as to maintain the vertical distance between port closing and port opening and isolate the effect of timing changes applied to the control sleeve so that a timing change does not vary the quantity setting and vice versa.

The objects of this invention are accomplished by providing in a distributor type fuel injection pump a cam operated plunger having means for rotating the plunger simultaneously with its reciprocation. A horizontal slot in the external periphery of the control sleeve is connected to a speed responsive device to control the timing of fuel injection of the pump. The path of the port on the plunger which sequentially opens and closes as it reciprocates and rotates in the sleeve forms a wavy curve having a constant velocity portion of the curve which defines a predetermined angle. The metering slot on the external periphery of the control sleeve is formed at an angle duplicating the lead of the constant velocity portion of the port curve. Accordingly any change in timing due to raising and lowering in the sleeve does not change the effective length of the pumping stroke for fuel injection. Accordingly the metering control is independent of the timing control and each control separately controls its function of timing and metermg.

Referring to the drawings:

FIG. 1 is a top view of the fuel injection pump and governor assembly;

FIG. 2 is a cross section view of the fuel injection pump and governor assembly mounted on an engine taken on line ll-ll of FIG. 3;

FIG. 3 is a cross section view taken on line III-III in FIG. 2;

FIG. 4 is a cross section view taken on line lV-IV on FIG.

FIG. 5 is a cross section view with the upper portion taken on line V-V and the lower portion taken on line V'-V of FIG. 1;

FIG. 6 is a cross section view taken on line Vl-Vl of FIG.

FIG. 7 is a view showing the development of the control sleeve with fragmentary views showing control elements on the external peripheral grooves;

FIG. 8 is an illustration of a sleeve movement for a sleeve having a vertical quantity control slot;

FIG. 9 is a three dimensional view of the control sleeve;

FIG; 10 is an enlarged portion of the development;

FIG. 11 is a plunger velocity control graph;

FIG. 12 is an illustration of relationship of dimensional and angular rotau'on of the control sleeve;

FIG. 13 is a front view of the quantity control slot in the control sleeve.

Referring to FIG. 2 the engine crankshaft 50 is rotatably mounted in the housing 51 and carries the drive gear 52 which drives a pump drive gear 3. The pump drive gear 3 is carried on the camshaft l and drives the cam 2 at engine speed.

The cam is a double lobe cam for operation with a four cylinder, four stroke cycle engine.

A pinion of the pump drive gear 3 engages the lower face gear of the cup gear 4 which is guided axially in the pump housing 5. It also contains a coaxially guided flat cam follower 6. The pump plunger 7 is fitted into the pump head 8. In addition to the reciprocal movement imparted by the cam 2 the plunger 7 is rotated by the cup gear 4 through the inwardly extending prongs 9 which engage slots in the drive plate 10. The drive plate 10 has a D-shaped opening in its center cooperating with the plunger outside diameter which has a flat on one side.

A control sleeve 11 is rotatably and slidably positioned on the intermediate portion of the plunger 7. The metering and timing mechanism for operating the control sleeve includes 2 levers, one for each function. The timing control is introduced into the control sleeve 11 by the crank 12. The crank arm 12 has a cylindrical portion 54 which is joumaled in the head 8 and has an eccentric pin 55 extending into a substantially horizontal slot 56 on the external periphery of the control sleeve 11. As the crank 12 is rotated in response to a movement of the lever 29, the control sleeve is moved upwardly or downwardly on the plunger which controls the timing function of the fuel injection pump.

Angular dephasing of the sleeve 11 provides the metering function of the control sleeve. The crank 13 also has a cylindrical portion 57 which is joumaled in the pump head 8 and has an eccentric pin 58. The crank 13 is connected to the lever 38 and provides quantity control. The pin 58 is equipped with a spherical end 72 engaging the slanted slot 65 in the control sleeve. Angular rotation or counterrotation of the control sleeve regulates the quantity of fuel injected.

The plunger 7 reciprocates in the head 8 and pumps by pressurizing fuel in the high pressure chamber 59. The pump head is equipped with a conventional delivery valve I4 and four outlet fittings 15 which are sequentially connected through distribution slot 60 on the plunger 7 to delivery valve 14. Fuel is supplied from supply pump 71 through the passage 16 and goes around the plunger by the annulus 17 and out through the passage 18 to a pressure relief valve, and back to the tank 70. It is understood that only surplus fluid is returned to the tank and that during the pumping cycle fuel is pressurized and delivered through the delivery valve to a combustion chamber (not shown).

The plunger 7 is seated on the cam follower 6 and the spring 61 on the upper spring seat 62 biases the lower spring seat 63 on the lower end of the plunger 7 downwardly to make a firm seating between the plunger and the cam follower 6. The cam 2 biases the plunger upwardly against the force of the spring 61 during the pumping operation.

The face gear cut in the upper portion of the cup gear 4 engages the governor drive pinion 19 which is positioned in sleeve bearing 20 and has a sliding fit with a governor shaft 21. The weight spider 22 is pressed onto the splined portion of the governor shaft 21. The weight spider is driven through the low frequency torque spring 23, connected between the gear 19 and the weight spider assembly 22. The governor weight 24 transmits centrifugal force through the shifter assembly 25 through the thrust bearing 26.

Springs

27 and 28 balance the axial vector of the centrifugal forces produced by the governor weights 24. The axial movement of the shifter assembly 25 is thus a function of the governor speed which in turn is in direct relationship to engine speed.

The timing advance and retard motion is initiated by the shifter assembly and is transmitted by the timing lever 29 to the timing crank 12. The timing lever 29 has a spherical end 30 which is engaged to a helical slot 31 in the cup end of the shifter 25.

The shifter assembly 25 is guided axially by a fixed pin 32 which registers in an axial slot in the cup of shifter assembly 25. Initial adjustment of the pump timing, which for the purpose illustrated is at port closing, is made from the outside adjusting screw 33 which moves an eccentric pin serving as a fulcrum for the timing lever 29.

The metering function provides a rotational movement of the control sleeve 11. The metering movement is transmitted through a conventional floating fulcrum arrangement from the throttle lever 34 through the fulcrum assembly 35, governor yoke 36, which engages the shifter by means of pins 37, through the lever 38 to the metering crank arm 13. Any other control arrangement such as torque limiter, starting boost, pressure compensator or other modifying sensors can be mounted on the

covers

39 and 40 for convenient interaction with the basic governor mechanism. Exterior adjustments 41 and 42 are respectively high idle and low idle stops.

FIG. 7 illustrates the development of the control sleeve and the curve produced by the path of the port 75 in the plunger 7 as it simultaneously reciprocates and rotates within the control sleeve 11. The spill slots 80 are shown in FIGS. 7 and 8 and their relationship with the curve formed by the movement of the port in the plunger. In a conventional timing control of distributor type pump, a timing change varies either start or ending of fuel injection. This also varies the effective stroke length which is undesirable. This invention however provides a means whereby the effective pumping stroke remains constant with timing variations. With the separate cranks controlling the timing and metering as shown in FIGS. 7, 8, 9 and 10, crank arm 12 changes timing by moving the control sleeve 11 up and down. Crank arm 13 changes the quantity of fuel injected by moving the sleeve in a horizontal plane in a clockwise or a counterclockwise rotation. The slot 65 engaging the crank arm 13 for quantity control is slanted. When the slot 65 engaging the end 72 of crank arm 13 is positioned to the same lead as the angle formed by the constant velocity portion of the curve 85, the effective stroke remains constant notwithstanding timing variations. Accordingly the timing control and the metering or quantity control provide control of the control sleeve which is unaffected by the movement of the other control lever.

FIG. 11 shows the plunger movement generated by a typical cam profile in an injection pump subdivided into three portions. The first portion is needed to accelerate the plunger and shows a rising velocity. The last portion 181 shows the movement caused by the nose of the cam over which the plunger decelerates, and comes to rest momentarily at the top of the stroke; and the intennediate portion 182 which is used essentially for the injection itself. This intermediate portion is made typically with either a constant velocity, as shown in solid line on FIG. 11 or a somewhat variable velocity shown by the dotted line 183 in FIG. 11 which can be approximated by an average constant value. If we look at the trace of the port against the inside diameter of the sleeve this curve is approximately sinusoidal, or preferably termed a wavy curve.

Referring again to FIG. 11, an early injection is shown at the beginning of the constant velocity portion of the cam and a late injection during the later part of this portion. Because both injections are at constant velocity and have the same duration or the same angle of plunger rotation, both will have the same effective stroke and will deliver equal quantities of fuel.

The control sleeve of the type referred to in the description always has the injection controlled by a horizontal sleeve edge and a slot edge. Either edge can be used to start or end an injection. In the following figures the lower edge of the sleeve controls port closing and the left hand edge of vertical slot controls port opening.

FIG. 8 shows effect of retarding the start of injection when the sleeve is lifted by the amount AY without rotation of the sleeve. Port closing occurs later by this amount of effective stroke, while the port opening is still at the same point as before.

FIG. 10 shows what happens if, in addition, we rotate the sleeve moving it to the right by the amount AX. This amount is chosen in such a way as to add AY to the effective stroke so that the total effective stroke remains unchanged. The amount AX by which we rotated the sleeve corresponds to an angle of rotation of AB. This angle AB is required to maintain constant effective stroke when we lift the sleeve by the amount AY.

Assuming that the slope of the constant velocity portion of the cam continues indefinitely, then a rotation of the sleeve 360 will raise the sleeve by the amount Y, maintaining the original total effective stroke. By an analogy with a screw and nut this is known as the lead or the amount by which a nut advances axially when rotated a complete turn. Therefore, the inclined control slot on the outside of the sleeve makes an angle with the horizontal which has the same lead as the angle which the path of the port makes on the inside of the sleeve. Mathematically it is expressed as follows:

Y constant. Where Y lead.

On the inside diameter of the sleeve:

tana=A Y/AX Y/1rd l where d= inside diameter of sleeve 1 7rd tana ll On the outside of this sleeve at the diameter D on which the quantity control knob (72) contacts the inclined slot, we have: tan a =Y/1rD (see FIG. 5) or, substituting from ll tan a =d/D tan a m Therefore, the correct statement is: the control slot angle with horizontal is equal to angle a on the sleeve inside diameter multiplied by the ratio of the diameters d/D.

The operation of this device is described in the following paragraphs. When the engine, is in operation the engine crankshaft 50 carrying the drive gear 52 drives the pump drive gear 3. The drive gear 3 drives the cup gear 4 which in turn is connected to the drive plate 10 which rotates the plunger 7v Simultaneously with rotation of the plunger 7 the camshaft l carrying the cam 2 is rotated. The cam 2 is a double lobe cam and it rotates at engine speed. The plunger 7 is reciprocated simultaneously with its rotation causing port 75 to define curve as shown in FIGS. 7 and 9. The governor 66 is also driven by the cup gear 4 which drives the governor drive pinion 19. The flyweight spider 22 is driven through the torque spring 23 thereby producing an axial movement of the shifter assembly 25 in response to speed of rotation of the flyweight. This in turn produces the axial movement of the shifter assembly which controls the timing and metering function supplied to the fuel injection pump.

The control sleeve 11 is rotatably and reciprocably mounted on the plunger 7. The control of timing is provided through the timing lever 29 which is connected to the shifter assembly 25. As the speed increases the flyweights 24 move radially outward shifting the shifter assembly to the right as shown in H6. 3. This in turn causes the spherical end 30 to move in the slot 31 causing the pivoting of the shifter lever 29 on its fulcrum screw 33. With an increase in engine speed the lever moves to lower the control sleeve 11 which advances timing of the fuel injection. A reverse function produces a lifting of the control sleeve which in turn retards the timing of the fuel injection.

The throttle lever 34 is a manually controlled lever which moves the throttle assembly and the throttle arm 35. The throttle arm 35 is pivoted on the shaft 170 which in turn pivots the end of the lever 36. This in turn moves the metering lever 38, crank arm 13, and rotates the control sleeve 11. The shifting movement of the shifter assembly to the right with increased engine speed causes rotation of the lever 36 and the metering lever 38 and rotation of the control sleeve. This in turn will cause the control sleeve to rotate counterclockwise or shift to the right as viewed in FIG. permitting the path of the port in the plunger to move through a larger segment of the land 172, thereby increasing the time which the port is closed. The reverse situation is produced when the sleeve is rotated in the opposite direction aNd the quantity of fuel is decreased. Consequently the port is closed for a shorter length of time and the fuel injection duration is for a shorter period. This is shown in FIG. 8 by moving the path of the port 75 to the right to cause a shorter duration of the closed port and consequently reduce quantity of fuel injection.

It can alsobe seen that if the sleeve is moved upwardly or downwardly in response to the timing function that the duration of fuel injection is not changed since the lead of the slot 65 is substantially the same as the constant velocity portion 74 of the curve 85. The port closes at the point where the port passes under the lower edge 90 of sleeve 11 in FIG. 10 and opens when the port passes over the edge 79 of the groove 80. Regardless of whether the lower edge of sleeve 11 is in retarded position at 76 or in advanced position at 77, the duration of the closed port condition during fuel injection remains substantially constant. Accordingly, a timing change does not affect duration of fuel injection.

The preferred embodiments of this invention have been illustrated and described.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel injection pump for an internal combustion engine comprising, a pump housing defining a cylindrical bore and a plunger received in said bore defining a fuel injection pumping chamber and a fuel supply chamber, means simultaneously reciprocating and rotating said plunger to define a predetermined angular motion of the plunger during fuel injection, said housing and said plunger defining a fuel supply passage and a fuel discharge passage in communication with said pumping chamber, a control sleeve in saidsupply chamber receiving said plunger, said sleeve defining a sleeve edge and a spill groove on the inner periphery of said sleeve, said plunger defining passage means and a spill port connected to said pumping chamber and selectively and alternatively passing over said sleeve edge and said spill groove to control fuel injection, said control sleeve defining a horizontal peripheral timing slot and a diagonal peripheral metering slot on the external periphery of said control sleeve with said diagonal slot defining a predetermined constant relationship to the angular motion of said plunger, a speed responsive device, a timing control linkage connected between said speed responsive device and said control sleeve for engaging said sleeve in said timing slot for controlling the timing of said fuel injection pump, a fuel quantity control linkage connected between said speed responsive device and said control sleeve for engaging said sleeve in said metering slot for controlling the metering of said fuel injection pump.

2. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said means simultaneously reciprocating and rotating said plunger moves said spill port in said plunger through a curve having constant velocity portion defining a predetermined axial advance per degree rotation of said plunger, said metering slot defines an axial advance per degree rotation of said sleeve substantially equal to the axial advance defined by the constant velocity portion of said curve to thereby permit the quantity fuel setting to remain constant when injection timing is changed.

3. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said control sleeve includes a vertical spill groove on the internal periphery of said control sleeve to spill pressurized fluid from said pumping chamber for termination of fuel injection during operation of said fuel injection pump.

4. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said means reciprocating and rotating said plunger include a face gear rotating said plunger and a cam reciprocating said plunger to thereby cause the spill port of said plunger to define approximately a sinusoidal path.

5. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said plunger defines an axial passage means in communication with said pumping chamber and a radial passage means defining said spill port connected to said axial passage means in said plunger.

6. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said means reciprocating and rotating said plunger includes a cam and gear driving said plunger to cause said spill port to define a curve having a constant velocity portion forming an angle of a predetermined lead on the internal periphery of said control sleeve, said sleeve defines said metering slot on its external periphery at another angle having substantially equal lead to the angle of the constant velocity portion of said curve, said control sleeve defines said horizontal timing slot on its external periphery connected to said timing control linkage to thereby provide metering and timing function of said fuel injection pump.

7. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said control sleeve defines a plurality of vertical spill grooves on its inner periphery.

8. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said control sleeve defines at least one substantially vertical spill groove on its internal periphery and said metering slot means includes a helical slot on its external periphery.

9. A fuel injection pump for an internal combustion engine as set forth in claim 1 wherein said control sleeve defines at least one vertical land and groove defining said spill groove on its inner periphery, said means simultaneously reciprocating and rotating said plunger causes said spill port in said plunger to define a diagonal path across a portion of said land whereby movement of the spill port over the lower edge of said sleeve initiates injection and movement to the edge of said groove terminates fuel injection.

10. A fuel injection pump for an internal combustion engine as set forth in claim 9 wherein said timing and quantity control linkages include means axially moving said sleeve on said plunger to control timing and rotatably moving said sleeve on said plunger to control quantity of fuel injection.

Claims

1. A fuel injection pump for an internal combustion engine comprising, a pump housing defining a cylindrical bore and a plunger received in said bore defining a fuel injection pumping chamber and a fuel supply chamber, means simultaneously reciprocating and rotating said plunger to define a predetermined angular motion of the plunger during fuel injection, said housing and said plunger defining a fuel supply passage and a fuel discharge passage in communication with said pumping chamber, a control sleeve in said supply chamber receiving said plunger, said sleeve defining a sleeve edge and a spill groove on the inner periphery of said sleeve, said plunger defining passage means and a spill port connected to said pumping chamber and selectively and alternatively passing over said sleeve edge and said spill groove to control fuel injection, said control sleeve defining a horizontal peripheral timing slot and a diagonal peripheral metering slot on the external periphery of said control sleeve with said diagonal slot defining a predetermined constant relationship to the angular motion of said plunger, a speed responsive device, a timing control linkage connected between said speed responsive device and said control sleeve for engaging said sleeve in said timing slot for controlling the timing of said fuel injection pump, a fuel quantity control linkage connected between said speed responsive device and said control sleeve for engaging said sleeve in said metering slot for controlling the metering of said fuel injection pump.