US3146716A

US3146716A - Fuel supplying mechanism

Info

Publication number: US3146716A
Application number: US161863A
Authority: US
Inventors: Dreisin Alexander
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1961-12-26
Filing date: 1961-12-26
Publication date: 1964-09-01
Anticipated expiration: 1981-09-01

Description

p 1, 1964 A. DRElSlN 3,146,716

FUEL SUPPLYING MECHANISM 1 Filed Dec. 26, 1961 2 Sheets-Sheet l United States Patent 3,146,716 FUEL SUPPLYING MECHANISM Alexander Dreisin, Olympia Fields, Ill., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Dec. 26, 1961, Ser. No. 161,863 3 Claims. (Cl. 103-2) This invention relates to a fuel supplying mechanism of the type including a distributor type fuel injection pump. More particularly, this invention relates to a fuel supply pump for delivering fuel at an intermediate pressure to a fuel injection pump and relates to the gear train for rotating the injection pump plunger.

In a fuel injection system for a compression ignition engine, it is customary to employ a fuel supply pump for delivering fuel to a fuel supply chamber of the fuel injection pump. The fuel supply pump delivers fuel which is maintained at an intermediate pressure, that is, a pressure lower than the pressure of the injected fuel delivered by the injection pump and higher than the atmospheric pressure at which the fuel supply tank is normally maintained. Gear type pumps have heretofore been employed to supply fuel to the fuel supply chamber communicating with the inlet to the injector pump, however, the overall cost and number of parts have been greater than desired.

It is an object of this invention to provide an improved injection pump which is lower in cost and requires less parts than prior injection pumps.

It is an object of the present invention to provide a simplified fuel supply pump arrangement wherein the gear train between the drive shaft and the pump plunger and the supply pump are advantageously interrelated.

It is a further object of this invention to provide an improved gear train for rotating the pump plunger of an injection pump.

It is a further object of this invention to provide an improved relief valve for a gear pump.

It is a further object of this invention to provide an improved relief valve for a pump without requiring additional parts.

I It is a further object of this invention to provide an improved fuel supplying system for a fuel injection pump.

These and other objects and advatnages of this invention will be apparent when the following description is read in conjunction with the drawings in which:

FIG. 1 is a section view of a pump incorporating the present invention;

FIG. 2 is a section view taken along the lines IIII of FIG. 1;

FIG. 3 is a section view taken along the lines TIL-III of FIG. 1.

Referring to FIG. 1, the distributor type fuel injection pump 11 is part of a fuel supply system for a compression ignition engine. A drive shaft 12 is adapted at its front end 15 to be connected to an engine, not shown, is journaled in cylindrical surface type bearings 13, 14 formed 1 in opposite side walls 16, 17, respectively, of the drive compartment 18 of the pump housing 19. The drive shaft 12 includes a cam portion 21 which includes a plurality of cams which reciprocate a pump plunger 22 as the shaft 12 is rotated. Reciprocation of the plunger 22 is effected through thrust transmitting means 23 interposed between the cam portion 21 and the plunger. The thrust transmitting means 23 includes a roller 24 and a barrel 26 reciprocably mounted in a sleeve 27, the latter being press fit into an inwardly disposed portion 28 of the housing 19. The plunger 22 has a pumping and distributing portion 31 which reciprocably and rotatably fits in fluid tight engagement with a plunger bore 32 in the head portion 33 of the housing 19. The head portion 33 is rigidly secured to the lower portion 34 of the housing 3,146,716 Patented Sept. 1, 1964 19 by a plurality of cap screws, not shown. A pumping chamber 36 is disposed at the upper end of the bore 32 and when the fuel is pressurized to a high injection pressure on the upward stroke of the pumping part 35 of the pumping and distributing portion 31, a delivery valve 37 permits the fluid to pass to the distributing part 38 of the pumping and distributing portion 31 of the plunger 22 through delivery passage 39. As the plunger 22 rotates, fuel is alternately delivered through an axially extending groove 41 in the periphery of the distributing part 38 of the plunger 22 to the injector supply passages 42.

A cylindrical fuel inlet portion 46 is coaxially formed in relation to the pumping and distributing portion 31 of the plunger 22. The fuel inlet portion 46 is disposed within a fuel supply chamber 47 and fluid is permitted to flow to the pumping chamber 36 from the fuel supply chamber 47 when inlet ports in the form of grooves 48 of the control sleeve 49 register with inlet ports 51 in the fuel inlet portion of the plunger. Rotation and reciprocation of the sleeve 49 also controls beginning and ending of injection. The inlet ports 51 are connected with the pumping chamber 36 by an interior passage 52 formed in plunger 22 on the axis 50 thereof. The sleeve is rotatably and reciprocably positioned relative to the housing 19 by a control rod 53 which is reciprocably and rotatably mounted in a bore 54 in wall 17.

The plunger 22 is rotated by a gear train connected to the drive shaft 12 which includes a gear 56 nonrotatably connected to a drive plate 57 through a pair of gears 58 on gear 56. Only one of the gears 58 is shown. The plate 57 has a control opening 59 for slidingly receiving a torque transmitting portion 60 of plunger 22. Opening 59 and portion 60 are so formed as to cause the plunger 22 to rotate with the plate 57. A hearing surface 61 on the gear 56 is in thrust transmitting relation to a thrust washer 62 which rotates with gear 56 and bears against thrust plate 63 held in place by a snap ring 64. The gear train for rotating the plunger 22 also includes a gear 66 formed on a countershaft 67 in meshing relation with gear 56 and a gear 73 which meshes with a gear 74 coaxial with and nonrotatively secured to the drive shaft 12. The countershaft 67 includes a cylindrical journal 68 between gears 66 and 74 which rotates in a bearing surface 69 of wall 17 and a journal surface 71 in bearing engagement with a bearing surface 72 in portion 28 of the housing 19. The journal portion 68 of the countershaft 67 is of at least as large a diameter as the outside diameter of gear 66, thereby permitting the gear 66 to pass through the opening presenting bearing surface 69.

Referring to FIGS. 1, 2 and 3,

gears

73, 74 are disposed between a pair of axially facing surfaces 76, 77 and semicylindrical surfaces 78, 79 formed in the Wall 17. An inlet passage 81 and an outlet passage 82 are formed in the wall 17 of the housing. The fuel inlet passage 81 and the fuel outlet passage 82 communicate with the

gears

73, 74 at transversely opposite sides, respectively, of the meshing teeth onthe

gears

73, 74. The

bores

86, 86 at the end of the

passage

81, 82, respectively, form inlet and outlet chambers in the wall 17 at transversely opposite sides of the teeth of the

gears

73, 74 which are in mesh. Thus, the

gears

73, 74 and surfaces 76, 77, 78, 7 9 constitute the essentials of a positive displacement gear type pump 75. The surface 77 in axially confronting relation to the

gears

73, 74 is formed on an annular plate 87 and is axially shiftably supported in the wall 17 of the housing by a cylindrical surface 88. The outside circumference 89 of the plate 87 is slightly smaller in diameter than the diameter of the cylindrical surface 88. A resiliently deformable retainer 91 constitutes biasing means for urging the plate 87 against the

gears

73, 74 and against. a flat surface 92 formed in the wall 17 at right v3 angles to the axis 3 of the drive shaft 12 and the axis 94 of the countershaft 67. The retainer 1 is a snap ring having circumferentially facing

ends

96, 97 defining a gap.

Conically shaped

camming surfaces

101, 102 are formed on the housing 19 and retainer at in complementary and axially facing relation to one another. Camming surface 191 is formed on one axial side of an annular recess 1%. When the pressure in the pump exceeds a predetermined value, the plate 87 will move to the right forcing the retainer 91 to contract through the camming action of the camming surfaces 16 1, 1512. Such axial movement will permit the fuel to escape to the governor compartment 103. Fuel in the governor compartment 163 is at approximately atmospheric pressure and is permitted to return to the fuel tank 196 through a conduit 167, schematically illustrated. Actually conduit 1%? may be so positioned that the governor compartment is maintained full of fuel to insure lubrication of parts therein. Fuel is drawn from tank 106 by a conduit 108 which is connected by a suitable fitting 1'69 to inlet passage 81. The outlet passage 82 is connected to a full flow filter 111 by a conduit 112. Fluid flowing from filter 111 passes to the supply chamber 47 through a con duit 113.

Wear particles of the drive compartment 18 are pre vented from passing to the fuel supply compartment 47 The fuel flowing from the supply chamber 47 to the drive compartment 18 is directed to the governor compartment by way of bearings 13, 14. Fuel lubricating journal type bearing 13 and mating bearing surface 117 on shaft 12 flows axially to the left to a cavity 122 defined by a low pressure seal 121, shaft 12 and cap 118 which forms a part of wall 16. The cavity 122 is connected to the governor compartment 163 through a passag 123 formed in the shaft 12 and a recess 116 in gear 74. A fiat 126 is formed on the shaft 12 to drivingly connect the gear 74 and this flat extends axially to the left, as viewed in FIG. 1, sufficiently to provide a small connecting cham her 127 at the end of passage 123. Fuel also flows from the drive compartment to the governor compartment be tween bearing surfaces 14 and journal type surface 128 A pressure regulating valve 131 is provided in the wall 17 intermediate the fuel supply chamber 47 and the governor compartment 1%. The governor compartment 103, the fuel tank 16-6 and fuel supply passage 81 are at a low pressure and may be considered the low pressure zone of the fuel system. The outlet passage 82, conduit 112, filter 111, conduit 113 and fuel supply chamber 47 are at an intermediate pressure as regulated by the valve 131 and these portions of the fuel supplying mechanism may be thought of as being an intermediate pressure zone. The pressure chamber 36, nozzle supply passages 42 and passage 39 are cyclically at a high pressure and may be considered a high pressure zone. When the fuel filter 111 becomes clogged, pressure in conduit 112 and chamber 86' goes up and then the plate 87, retainer 91 and camming surfaces 101 and M2 function as a relief valve for the pump.

An additional relief valve function may be provided by the pressure plate 87. By constructing the pressure plate of suitable resilient material, such as carbon steel of proper thickness, the pressure plate will bulge at its center axially away from the rotary pumping elements or gears 73, 74 to permit fuel to escape to the governor compartment when the pressure of the fuel in the pump reaches a predetermined value. The resilient plate may be used as a relief valve independently of the tapered surface, snap ring arrangement or vice versa. The plate is preferably constructed to relieve pressure at a somewhat lower pressure than required to move the circumference of the plate axially by camming action of surfaces 161, 162. Thus a two step pressure relief valve arrangement is provided which protects the system against damage should the filter 111 become clogged. The resilient plate will deflect to relieve pressure at low output, for instance, and the contracting snap ring will permit additional fuel bypass flow at higher pump output.

The gear type pump 75 utilizes spur gears 73, 74 of the gear train employed to rotate the plunger thereby effecting a savings in cost. By placing the pump 75 in wall 17, the fuel escaping through the pump relief valve, of which pressure plate 87 and retainer 91 are a part, conveniently passes into the governor compartment 103 which is at approximately atmospheric pressure. If pressure plate 87 is removed upon contraction and removal of retainer 91, the gear 74 and the countershaft with its integrally formed gears 66, 73 and bearing surfaces 68, 71 may be easily removed for replacement, if required.

Since a full flow filter is used in the fuel supply zone of the system, it is desirable to provide a relief valve for the supply pump 75. By providing a resilient plate 87 and camming surfaces on the snap ring type retainer )1 and the side wall of recess 100, an effective two step relief valve is provided without increasing the number of parts required for the injection pump. It should be understood that the pump relief valve relieves pressure at a higher pressure than does regulating valve 131.

The illustrated fuel supplying system is also shown in copending patent application of Alexander Dreisin and Walter A. Parrish, Jr., Serial No. 161,862, filed December 26, 1961, Fuel Supplying Mechanism.

It is intended that this invention includes such modifications and other embodiments as are within the scope of the appended claims.

What is claimed is:

1. In a fuel injection pump of the type including a housing with a drive compartment and a governor compartment, the combination of a shaft rotatably mounted in said housing and having a cam within said drive compartment, a bore in said housing, a plunger reciprocated in said bore by said cam to pump fuel, a wall driving said drive and governor compartments and having a cylindrical journal, means for rotating said plunger to distribute fuel to a plurality of outlets including a first gear mounted in said housing in coaxial relation to and rotating with said plunger, a countershaft having a cylindrical bearing portion in cooperative engagement with said journal and having second and third gears formed integrally and coaxially therewith at axially opposite sides, respectively, of said bearing portion, said journal having a diameter at least as great as the outside diameter of said second gear, a fourth gear connected to said shaft for rotation therewith in meshing relation with said third gear, said second gear meshing with said first gear, surfaces in said wall in axially and radially confronting relation to said third and fourth gears, an end plate releasably secured to the governor compartment side of said Wall in axially engaging relation to said third and fourth gears and inlet and outlet chambers formed in said wall at transversely opposite sides of the meshing teeth of said third and fourth gears whereby the latter operate as a fuel supply pump.

2. The structure set forth in claim 1 wherein said end plate is annular and resiliently deflects axially to provide pressure relief for said supply pump upon the pressure therein reaching a predetermined value.

3. The structure set forth in claim 2 and further comprising an annular retainer resiliently flexible radially and securing said end plate to said wall and cooperatively engaging annular camming surfaces on said wall and retainer at the radially outer periphery of the latter, said retainer resiliently deflecting radially allowing said outer periphery of said end plate to move axially to permit fluid to escape from said supply pump to said governor compartment upon said pressure in said supply pump exceeding a value greater than said predetermined value.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Parsons Aug. 21, 1945 Westbury May 20, 1952 Hartmann Dec. 30, 1952 Dale et a1. June 16, 1953 High Feb. 2, 1954 Garnier Feb. 22, 1955 Carpigiani J an. 30,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 146,716 September 1, 1964 Alexander Dreisin It is hereby certified that error appears in the above numbered patent req'iiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 37, for "driving" read dividing Signed and sealed this 22nd day of December 1964.

(SEAL) Attest:

ERNEST w. SWIDER EDWARD J. BRENNER Aitesting Officer Commissioner of Patents