US3368490A

US3368490A - Fuel pump and pressure equalization means therefor

Info

Publication number: US3368490A
Authority: US
Inventors: Michael A Virello
Original assignee: Standard Screw Co
Current assignee: Stanadyne LLC
Priority date: 1965-11-01
Filing date: 1965-11-01
Publication date: 1968-02-13
Anticipated expiration: 1985-02-13
Also published as: ES332965A1; GB1166291A; DE1302404B; DE1302404C2; SE331925B

Description

mlm'mllw l alummmh Feb. 13, 1968 M. A. VIRELLO l 3,368,490

FUEL PUMP AND PRESSURE EQUALIZATION MEANS THEREFOR Filed Nov. l, 1965 3 Sheets-Sheet 1 :Milli Q u llWNlllllHil I rg MICHAEL A. VIRE-ILL() ATTORN EYS Feb. 13, 196s M. A. WELL@ 3,368,490

FUEL PUMP AND PRESSURE EQUALIZATION MEANS THEREF'OR Filed NOV. l, 1965 3 Sheets-5h66*l 2 INVENTOR.

MlCHAEL A. VIRELLO www4/,Myx

ATTORNEYS Feb. 13, 196s M. A. VIRELLO 3,368,490

FUEL PUMP AND PRESSURE EQUALIZATION MEANS TI'IEREFORv Filed Nov. l, 1965 5 Sheets-Sheet (5 INVENTOR.

MICHAEL A \/l RELLO WWW/Mw ATTORNEYS United States Patent 3,368,490 FUEL PUMP AND PRESSURE EQUALIZATION MEANS THEREFOR Michael A. Virello, Bristol, Conn., assigner to Standard Screw Company, Wilson, Conn., a corporation of New .Ierse y Filed Nov. 1, 1965, Ser. No. 505,948

12 Claims. (Cl. 103-2) ABSTRACT F THE DISCLOSURE A fuel pump for pressurizing fuel to a high pressure and delivering the pressurized fuel to a distributor passage of a rotating distributor which has an outlet port sequentially registrable with a plurality of delivery passages connected to the several injection nozzles supplied lby the pump, wherein the rotating distributor has a plurality of equalizing passages between the distributor passage and ports on the periphery of the rotating distributor which are registrable simultaneously with each of the delivery passages after the delivery of fuel thereto so as to equalize the residual pressure in the delivery passages and including a delivery valve between the fuel pump and the distributor passage for maintaining a positive pressure in the distributor passage and the delivery passages.

The present invention relates to fuel pumps of the type utilized in fuel injection systems for delivering measured charges of fuel to the nozzles of an internal combustion engine.

A principal object of this invention is to provide an improved means for equalizing the residual -pressures 1n the injection nozzle conduits after each injection. Included in this object is the provision of means for balancing the radial hydraulic forces acting on the distributor rotor.

Another object of this invention is to provide a means for eliminating or preventing air pockets in the injection nozzle conduits and a chamber in the rotor which delivers fuel thereto.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth, and the scope of the application of which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a longitudinal cross-sectional View, partly broken away, of a fuel injection pump embodying the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2 2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken along line 3 3 of FIG. 2;

FIG. 4 is an enlarged cross-sectional View taken along line 4 4 of FIG. l, and

FIG. 5 is a fragmentary cross-sectional View taken along line 5 5 of FIG. 1.

The following is a detailed description of the invention.

Referring now to the drawings in detail, in which like numerals refer to like parts throughout the several figures, a pump exemplifying the present invention is of the type now commercially available for supplying fuel charges to an associated internal combustion engine. The pump comprises an external housing or casing having an axial bore or opening 12 rotatably supporting a pump rotor or distributor 14.

At the right end of the housing 10, as viewed in FIG. 1,

there is mounted a vane-type fuel supply or transfer pump i Patented Feb. 13, 1968 fuel to the transfer pump 18 from an inlet pipe 22 which is connected to a fuel supply reservoir. The transfer pump delivers fuel under pressure through an outlet passage 24 4in the housing 10 to an air separator 26 from whence the fuel flows through a passage 28 (FIG. 2) in the housing 10 to a longitudinal bore 30 in the housing. A slideable spring lbiased pressure regulating valve 32 (FIG. 3) iS mounted in the bore 30 for regulating the output pressure of the pump 18. Regulating valve 32 delivers fuel to the centrifugal metering valve 34 at a pressure correlated with the speed of the driving engine through conduit 33 and returns excess fuel to the transfer pump inlet conduit 20 through conduit 35.

The high pressure charge pump generally denoted by the numeral 40 is formed by a transverse bore 42 in rotor 14 in which are slideably mounted a pair of opposed plungers 44. The outer ends of the plungers engage against shoes 46 which are slideably mounted in transverse passages 48 formed by the bifurcated end 47 of a separable drive shaft 60 aligned with bore 42. As shown in FIG. 4, the bifurcated end of drive shaft 60 also provides a pair of fiat opposed shoulders which engages complementary shoulders 45 on the rotor 14 to drive the same.

Surrounding the rotary member 14 is a generally circular or ring-like cam ring 50 preferably constructed of hardened steel which encircles the rotor 14 in the plane of revolution of the plungers 44 and is mounted for angular `adjustment within an annular bore 49 in the pump housing. The cam has 'a plurality of pairs of diametrically opposed inwardly extending cam lobes 52 which are adapted to actuate the plungers 44 inwardly simultaneously for discharging fuel from the pump, it being understood that the rollers 43 and the roller shoes 46 are disposed between the plungers 44 and the cam 5t) whereby the rollers 43 act as cam followers for translating the cam contour into this reciprocal movement of the plungers 44. The C-shaped ring 56 secured to the charge pump by a screw fastener 58 (FIG. 4) provides an adjustable outer resilient top for the roll shoes 46. A seal 62 is provided to prevent leakage of fuel into or out of between the shaft 60 and the housing 10i.

Upon rotation of the drive shaft 60, the transfer pump 18 and the charge pump 40 are rotated to supply measured charges of fuel under pressure to a plurality of fuel pump outlets 64 having suitable connections with the fuel injection nozzles of an associated engine. During the outward or intake stroke of the plungers 44, fuel is delivered to the charge pump from the metering port 41 by a passage 66 in the housing 10, an Iannulus 51, and -a diagonal passage 68 in the rotor 14. During the inward or discharge stroke of t-he plungers 44 fuel is delivered under high pressure by an axial passage 76 to a pressure-operated delivery valve 77 and a generally radially extending distributor passage 78 adapted for sequential registration with a plurality of angularly spaced radial delivery passages 63 (shown as four in number in FIG. 5) in fluid communication respectively with a plurality of pump outlets 64. A one-way valve 68a prevents reverse flow through passage 68 during the discharge stroke of the plungers 44.

The metering valve 34 may be adjusted in any suitable manner, and in the illustrated embodiment is shown as being a spool valve axially adjustable 'land rotatably vdriven by the centrifugal governor 31 against the force of spring 29, the bias of which may be adjusted or varied by lever 25. The governor is positively driven by its gear 84 which engages gear 85 mounted on drive shaft 60. Inasmuch as the axial force of centrifugal governor 31 is a function of engine speed, the position of the metering valve 34 and hence the restriction offered by the metering port 41 due to the axial shifting of the spool 34 will govern the engine at a speed which may be selected by varying the bias of the compression spring 29.

Referring now specific-ally to FIG. 4, there is shown a transverse bore 100 in the housing 10 in which an axially movable plunger 102 is reciprocably mounted. A passage 104 (FIG. l) from the air separator 26 is shown as being in communication with the bore 100 to deliver regulated transfer pump outlet pressure thereto. In the illustrated design, the plunger 102 includes a pilot valve 105 positioned in a chamber 106, one end of which communicates with housing passage 104 through passage 108 in plunger 102. A one-way valve is positioned in pilot valve 105 to prevent the reverse flow of uid through the passage 108 as a result of intermittent rotary force imposed on the plunger 102 as due to the oper-ation of the charge pump.

Pilot valve 105 is provided with an adjustable biasing spring 109 which engages the end of a threaded adjusting screw 103 at the end of transverse housing bore 100. Spring 109 opposes the transfer pump outlet pressure acting on the right end of the pilot valve with the result that 'the transfer pump output pressure will urge the plunger 102 to the left, as seen in FIG. 2, against the bias of compression spring 109.

Pilot valve 105 is also provided with an annular land 110 which is axially shiftable over port 111 in the plunger 102. Port 111 communicates through passage 112 to a chamber 113 formed in the end of transverse housing bore 100 to deliver fuel under pressure thereto when annular land 110 of the pilot valve is moved to the left to provide communication between passage 106 and port 111 via annulus 107 and passage 112. Inasmuch as the transfer pump pressure is a function of engine speed, the balanced position assumed by the pilot valve is determined by the equilibrium between the forces imposed thereon by the transfer pump pressure and the spring 109. This, in turn, determines whether the port 111 communicates with annulus 107 to receive additional fuel from the transfer pump (-and hence shift plunger 102 to the left to advance the time of injection) or the port 111 communicates with passage 114 to dump a portion of the fuel trapped in the chamber 113 into the pump housing through passage 114 to permit the plunger 102 to move to the right. As shown in FIG. 4, the left end of annulus 107 is of reduced cross section to throttle the ow of fuel therethrough and stabilize the operation of the pilot valve.

Since one end of the spring 109 engages stationary screw 103, it will be apparent that when the pilot valve is in equilibrium, the port 111 will be automatically closed by land 110 as the plunger 102 moves to the left by the increased fuel entering chamber 113.

For operatively connecting plunger 102 and cam 50, there is provided an arm 115 having -a cylindrical body 116 mounted in a complementary radial bore 118 in the plunger 102. The connector 115 has an integral head 120 closely received within a bore 101 of the cam ring 50 which serves as a socket therefor. The plunger 102 is recessed at 122 to receive a portion of the cam ring 50 extending within the bore 100, and the connector 115 is preferably dimensioned to reciprocate with the plunger 102 within the peripheral confines of the bore 100. A snap ring 124 seated in an annular groove in the connector 115 prevents excess axial movement of the connector toward the cam ring.

Referring now particularly to FIG. 5, there is illustrated in accordance with this invention a means for equalizing the residual pressures in the delivery passages 63 after each delivery of fuel to any of them by distributor passage 78. As illustrated, a plurality of equalizing passages 130 are provided in the rotor 14 and are positioned to provide ports on the periphery lof distributor 14 which are in the same radial plane as the discharge port of distributor passage 78. The equalizing passages 130, which are shown as being four in number to correspond with the number of injection nozzle passages included in the illustrated pump, communicate at their inner ends with the distributor bore 132 downstream of the delivery valve 77. The equalizing passages are also angularly disposed so as to simultaneously register respectively with the four delivery passages 63 when the distributor passage 78 is not in registry with any of them. It will thus be seen that the equalizing passages 130 provide communication between the delivery passages 63 and the distributor bore 132 of the distributor rotor after each delivery of high pressure fuel by the charge pump 40.

Since the excess or residual pressure in the passage 63 into which the high pressure fuel has just been discharged by the distributor passage 78, this pressure is automatically reduced and equalized with the pressures in each of the other delivery passages 63.

Significant to this invention is that the excess pressure in the last-to-be pressurized delivery passage 63 will also insure that the pressure in the central bore 132 downstream of the delivery valve is built up to the same level as the pressure within such last-to-be pressurized delivery passage 63. This is important since it prevents or eliminates any voids in the central bore 132 and the delivery passages 63 by lilling the same with liquid (as contrasted with gaseous) fuel under pressure and thereby prevents variations in the quantity of fuel delivered to each injection nozzle due to sponginess resulting from voids in the central bore 132 or delivery passages 63. This is particularly important at low operating speeds where the quantity of fuel injection per injection is extremely small, and may in fact be inadequate to fill such voids during each delivery by the charge pump.

In addition to the foregoing, the provision for the equilization for the pressure in each of the passages 63 assures that the hydraulic loading on the distributor is balanced in a radial direction since the pressure in any one of the delivery passages 63 is counter-balanced by an equal and opposite pressure by the lfuel in the opposite delivery passage thereby to minimize the radial loading on the rotor.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

I claim:

1. In a fuel pump for an internal combustion engine, the combination of a member having a plurality of delivery passages, a rotatable lfuel distributing device associated with said member and having a fuel distributing passage registrable sequentially with each of said delivery passages during the rotation thereof for delivering fuel thereto, pumping means for supplying fuel under pressure to said fuel distributing passage, pressure equalizing means in continuous communication with each other and communicating with at least some of said delivery passages when said fuel distributing passage is out of registry therewith to equalize the residual pressure in such delivery passages.

2. The combination recited in claim 1 wherein the said pressure equalizing means provides communication between said delivery passages after each discharge of fuel from said fuel distributing passage.

3. In a fuel pump the combination of a casing having a plurality of fuel delivery passages for delivering fuel to the fuel injection nozzles of an associated engine, a fuel distributing member having a chamber provided with a fuel discharge port movable along a portion of said casing for communicating with said fuel delivery passages in sequence, and pressure equalizing means in continuous communication with each other and providing communication between said chamber and each of said fuel delivery passages after each delivery of fuel to one of said fuel delivery passages by said fuel discharge port to pressurize the fuel remaining in said chamber and in the delivery passages.

4. The combination recited in claim 3 wherein said fuel distributing member includes a charge pump and a passageway for delivering the output of the charge pump to said chamber.

5. The combination recited in claim 4 wherein a oneway valve is provided between said chamber and said charge pump to prevent the reverse flow of fuel therebetween.

6. The combination recited in claim 3 wherein said fuel distributing member rotates Within a bore of said casing and the delivery passages have ports at the bore thereof, said ports being equally angularly spaced to hydraulically balance the radial loading on the rotor.

7. The combination as recited in claim 3 wherein said pressure equalizing means comprises a plurality of equali- Zation passages respectively registrable with each of said fuel delivery passages after each delivery of fuel to one of said fuel delivery passages by said fuel discharge port and said equalization passages further communicate with said chamber for equalizing the pressure therein with that in said fuel delivery passages.

8. The combination of claim 1 wherein said pressure equalizing means provides communication between said delivery passages and said fuel distributing passage.

9. In a fu-el pump for an internal combustion engine, the combination of a member having a plurality of delivery passages, a rotatable fuel distributing device associated with said member and having a fuel distributing passage registrable sequentially with each of said delivery passages during the rotation thereof for delivering fuel thereto, a pump for supplying fuel under pressure to said fuel distributing passage, pressure equalizing means providing communication between at least some of said fuel delivery passages when said fuel distributing passage is not in registry therewith to equalize the residual pressure in such delivery passages, and means for maintaining a positive pressure on the fuel in said delivery passages when said pressure equalizing means are in communication therewith.

10. The combination recited in c laim 9 wherein the means for maintaining a positive pressure on the-fuel in the delivery passages is a one-way valve disposed in the path of the fuel between said pump and sai-d fuel distributing passage to prevent the reverse ow of fuel therebetween when the residual pressure in the delivery passages is being equalized.

11. The combination recited in claim 10 wherein said pressure equalizing means comprises a plurality of generally radial passages communicating with the fuel distributing passage downstream of said one-way valve.

12. The combination recited in claim 11 wherein said radial passages are equiangularly spaced in a plane of rotation through said rotatable fuel distributing device and are equal in number to the number of said delivery passages.

References Cited UNITED STATES PATENTS 3,023,705 3/1962 Heiser 10S-2.1 3,050,001 8/1962 Links 10S-2.1 3,099,217 7/1963 Bessiere 123-139 X LAURENCE M. GOODRIDGE, Primary Examiner.