US3304885A

US3304885A - Piston pump lubrication structure

Info

Publication number: US3304885A
Application number: US452090A
Authority: US
Inventors: Harold R Orth
Original assignee: International Harverster Corp
Current assignee: Navistar Inc
Priority date: 1965-04-30
Filing date: 1965-04-30
Publication date: 1967-02-21
Anticipated expiration: 1984-02-21
Also published as: DE1653477A1; GB1141705A

Description

Feb. 21, 1967 H. R. ORTH 3,304,885

PISTON PUMP LUBRICATION STRUCTURE Filed April 50, 1965 4 Sheets-Sheet 1 Iifi U 1 M M 57 95- m T R 3 2 INVEN 0 HAROLD R. ORTH ATT'Y.

Feb. 21, 1967 H. R. ORTH 3,304,885

PISTON PUMP LUBRICATION STRUCTURE Filed April 50, 1965 4 Sheets-Sheet {5 INVENTOR HAROLD R. ORTH BY 71 P. X

ATT'Y.

' j 7 H. R. ORTH 3,304,885

PISTON PUMP LUBRICATION STRUCTURE Filed April 50, 1965 4 Sheets-Sheet 4 HA ROLD R. ORTH United States Patent 3 304 885 PISTON PUMP LUQRIXEATION STRUCTURE Harold R. Orth, La Grange, IlL, assignor to International Harvester Company, Chicago, III., a corporation of New Jersey Filed Apr. 30, 1965, Ser. No. 452,090 6 Claims. (Cl. 103-162) This invention relates generally to variable displacement axial piston pumps and motors; and more particularly relates to axial piston pumps and motors having improved lubricating structures.

As is well known, when an axial piston pump is driven mechanically, it functions as a pump to pump a working fluid from a low pressure source into a high pressure outlet line; and when it is supplied with a relatively high pressure flow of fluid, the pump functions as a motor to supply a mechanical output of power. Consequently, while for purposes of simplification the invention will be referred to as a pump in the description and claims which follows, it should be clear that the invention may be employed with equal advantages when the invention is functioning as a motor.

In the usual case, axial piston pumps have been cooled and lubricated by submersion in a wet sump or fluid reservoir containing a fluid suitable for lubrication and cooling of the components of the pump. Unfortunately, such submersion results in considerable churning of the fluid increasing its operating temperature and decreasing pump etficiency. Increased fluid operating temperatures leads to pump overheating and maximum pump operating speed is limited severely with submerged lubrication.

Other axial piston pumps are lubricated by an external spray method to avoid power losses and overheating caused by oil churning. While the external spray lubrication method avoids the churning losses of submerged lubricataion, pump operating speeds are still severely limited by maximum safe operating temperatures; while the lubricant sprayed on the pump cools its external surfaces to some extent, some pump components are relatively inaccessible to the lubricating spray. Thus the rotating pump shaft is relatively inaccessible to external spray lubrication and must rely upon somewhat inadequate chance lubrication to prevent shaft wear and fretting, as in its splined drive areas, due to shaft deflection. Also, at high speeds contemplated of over 3000 r.p.m. with conventional lubricating methods such as external spray lubrication or submerged lubrication, pump overheating inevitably occurs due to centrifugal forces which tend to throw. lubricating fluid supplied to the pump centrifugally outwardly, keeping the lubricating fluid away from the internal components of the pump.

In hydrostatic transmissions incorporating two of the devices herein contemplated functioning individually as an axial piston pump and-as an axial piston motor coaxially arranged, power losses are considered very critically, and as would be expected, ways to avoid reductions in efficiency due to friction or overheating are constantly sought. Friction of the pump and motor valve plates rubbing together in operation of the transmission without sufficient cooling and lubrication tends to result in pump overheating and destruction of the valve plates. With relatively larger transmission units utilizing relatively larger valve plates having relatively larger rubbing surfaces, safe operating speeds are further limited. Additionally, pump and motor slippers and thrust plates have a rather limited operating life at high speeds and tend to become unserviceable after only a few hundred hours of operation, due to overheating and oxidizing of lubricant.

Thus, an object of the invention is to provide an improved axial piston pump.

Another object of the invention is to provide an axial piston pump having an improved lubrication structure to permit operation at higher speeds.

Still another object of the invention is to provide a simple relatively foolproof axial piston pump arrangement to achieve forced lubrication and cooling of the pump components.

Still another object of the invention is to provide an improved axial piston pump lubricating system to achieve selective lubrication of internally disposed pump compo nents such as pump shaft bearings, valve plates, and shaft splines as well as relatively inaccessible internal surfaces of pump slippers, slipper retaining guides and thrust plate.

Yet another object of the invention is to provide an improved axial piston pump structure to achieve internal lubrication of the pump components to permit safe operation of the pump at relatively high operating speeds of over about 3000 r.p.m.

A further object of the invention is to provide a lubricating system for an axial piston pump operating in a dry sump where pump components are not picking up lubricating fluid by rotation within a fluid, and to achieve lubrication of the pump without churning power losses associated with submerged pump operation.

Sill another object of the invention is to provide a forced lubricating system for a hydrostatic transmission incorporating an axial piston pump and an axial piston motor coaxially arranged and cooperating fo operation at high speeds of over about 3000 r.p.m., the lubricating system directing a central flow of lubricating and cooling fluid to internal components of the pump and motor.

These and other objects of the invention will become clear from the following description taken in conjunction with the appended claims and drawings, wherein:

FIG. 1 is,a somewhat schematic, simplified sectional view of an embodiment of an axial piston pump constructed in accordance with the present invention;

FIG. 2 is a somewhat schematic, sectional view of a hydrostatic transmission including an axial piston pump and an axial piston motor both constructed in accordance with the teachings of the present invention;

FIG. 3 is a somewhat schematic simplified sectional view similar to FIG. 1 of another embodiment of an axial piston pump constructed in accordance with the invention;

FIG. 4 is a schematic representation of a flow diagram of an axial piston pump as illustrated in FIGS. 1' and 3;

FIG. 5 is a schematic representation of a flow diagram of a hydrostatic transmission as illustrated in FIG. 2;

FIGS. 6 and 7 are end sectional views taken along the lines 66 and 7-7 respectively of FIG. 1;

FIG. 8 is an enlarged sectional view taken along the 0 line 88 of FIG. 6 showing a valve plate portion of the axial piston pump of FIG. 1;

FIGS. 9 and 10 are end sectional views taken along the lines 99 and 10-10 respectively of FIG. 3;

FIG. 11 is an enlarged sectional view taken along the line 11-11 of FIG. 9;

FIG. 12 is an enlarged somewhat schematic sectional view of another embodiment of an axial piston pump similar to the showings of FIGS. 8 and 11 but constructed without valve plates;

FIGS. 13 and 14 are end sectional views taken along the lines 1313 and 14-14 respectively of FIG. 12.

Referring to the drawings, FIG. 1 shows an axial piston pump 10 including a rotatable cylinder block 12 having a plurality of axially extending splines, the block being splined on a rotatable drive shaft 14 driven by an associated source of power such as a vehicle engine 15, FIG. 4, the shaft 14 having a plurality of axially extending splines 16 complementary to the cylinder block splines for rotation of the cylinder block with the drive shaft 14;

The cylinder block 12 has a plurality of axial cylinder bores 18 therein, each housing one of a plurality of reciprocable pistons 20, each of the pistons 20 having a ball or outer end 22 force fitted within individual sockets 23 provided for this purpose in a pump sockcted bearing surface or slipper 24. First and

second valve plates

32, 28 respectively are provided for receipt or exhaust of a fluid from the cylinder bores 18. The cylinder block 12 is biased by .a cylinder block spring 26 against the second or right valve plate 28 pinned to or integral with the cylinder block 12 for rotation therewith. The valve plate 28 comprises a bearing plate which may be but is not necessarily integral with the block 12 having a flat valving surface 30. Plate 28 rotates with respect to the first Valve plate or port plate 32 having a flat complementary valving surface 34 which bears or slides against the fiat face 38 of the right valve plate 28. The first valve plate 32 is pinned to a housing 36, although it may be integral with the housing 36, a portion of which is shown in the drawing, and is thus maintained stationary. The first and

second valve plates

32, 28 are formed with complementary arcuate

shaped ports

40, 38 for successive fluid communication with ports 42 in the cylinder bores 18 as the cylinder block 12 rotates to admit and exhaust a working fluid, not shown, to and from the cylinder bores 18, as is well known in the art.

The ball ends 22 of the pistons 28 cooperate with a swash plate assembly includin a swash plate 44 pivotable about the drive shaft 14 by means of a pair of trunnions 46, 48 having a plurality of trunnion bearings 50 comprising tapered roller bearings supporting the swash plate 44. As is well understood, the swash plate 44 is pivoted between a minimum displacement neutral position approximateiy as shown in FIG. 1 to maximum displacement positions, as shown generally in FIG. 2, at opposite sides of the center position in order to vary the fluid displacement of the pump. The pump drive shaft 14 is connected for rotation with an input shaft, not shown, to rotate the drive shaft.

The swash plate 44 has a generally cylindrical inner portion 54 with an annular thrust plate 56 therein providing a flat bearing surface 57 for the slipper 24 which slides thereon. A slipper retainer 58 and slipper retainer guide 60 are provided to maintain the slipper in bearing position against the thrust plate 56, the slipper retainer guide 60 being biased to the right, as viewed in the figure, by a slipper retainer spring 62. The slipper retainer guide 60 is splined to the shaft 14 for rotation therewith and has a generally spherical outer surface 64 on which a complementally spherically shaped inner surface 66 of the slipper retainer 58 slides.

First and second main shaft bearings 68, 70 are positioned at the left and right ends of the main shaft to support the shaft 14 for rotation within the pump housing 36.

In accordance with an important feature of the invention, the rotatable main shaft 14 is provided with an axially extending central passageway 74 in communication with a plurality of first, second and third radial passageways or openings 76, 78, 80 in communication therewith for receipt of a lubricating fluid. The first radial passageways 76 are comm-unicatively connected to the first main shaft bearing 68 which is in communication with a plurality of radially extending

passageways

84, 82 provided respectively in the first and

second valve plates

32, 28 to carry a lubricating fluid radially about the valve plates to dissipate the heat generated by the intermediate rubbing surfaces 34, 30 of the valve plates.

The splined area of the pump shaft 14, extending axially from an intermediate portion 86 of the shaft toward the right end of the shaft adjacent the pump slippers 24, is subject to considerable wear and fretting due to rotational deflection. In accordance with the invention, the splines 16 of the shaft and the splines, not shown, of the cylinder block 12 are slightly undercut to provide undercut spline passageways designated by the numeral 85 for the flow of lubricating fluid. The second or intermediate radial passageways 78 are positioned immediately adjacent the spline-d area at the left or valve plate end of the splines 16 and are in communication with the undercut passageways 85 provided in the splined area. The right hand end of the cylinder block is notched at points indicated by the numeral 86 and a plurality of radial openings 87 in line therewith are provided in the slipper retainer guide 60, the openings 87 being in communication with the intermediate radial passageways 78 by means of the undercut spline passageways 85 for receipt of lubricating fluid therefrom.

The third radial passageways 86 are positioned at the right end of the axially extending central passageway 74 at the right hand end of the pump shaft 14 leading to and being in communication with the right shaft bearing 70 to direct a flow of lubricating fluid through the hearing.

The annular thrust plate 56 has an inner edge 90 adjacent the slipper retainer guide 60 which edge 98 is chamfered so as to encourage the flow of lubricating fluid flowing radially outwardly from the openings 85, 87 to flow over surface 57 rather than through opening 89. Having now described the invention, its operation should be clear; however, for purposes of a better understanding of the invention, the manner in which the axial piston pump is lubricated and coo-led will be explained.

Conventional means 180, FIG. 4, are provided to direct a flow of lubricating fluid under pressure from a reservoir 182 to the pump 10 at the left end of the axially extending central assageway 74 in the pump shaft 14, with arrows indicating the direction of flow. Fluid enters the pump at the valve plate area and travels axially to the right through the passageway 74 entering the first, second and third radial passageways 76, 78 and 80. Lubricating fluid first enters radial passageway 76 flowing through and lubricating the main shaft bearings 68 and then flowing radially outwardly through the valve plate passageways 82, 84 to cool the valve plates, the fluid then being directed by conventional means, not shown, to a fluid reservoir 182, FIG. 4.

Another portion of the flow of fluid from the axial passageway 74 flows radially outwardly through passageways 78, to the right through the undercut spline passageways 85 where the flow of fluid lubricates and cools the splined area of the shaft which is highly stressed due to flexure of the shaft with a consequent tendency to wear out. The lubricating fluid continues through notches 86 provided in the right end of the cylinder block 12 in communication with openings 87 provided in the slipper retainer guide 60 where the chamfered thrust plate 56 encourages the lubricating fluid to flow over the chamfered edge of the thrust plate rather than through an opening 89 provided in the thrust plate 56. The lubricating fluid from the intermediate radial passageways 78 then sprays centrifugally outwardly from the slipper retainer guide openings 87 to lubricate and cool the surfaces of the slipper retainer guide 60, slipper 24 and slipper retainer 58; and the fluid continues in a spray radially outwardly through openings, not shown, provided in the swash plate 44 to lubricate the trunnion bearings 50, as indicated by the arrows, before returning to the fluid reservoir 182, FIG. 4.

The third radial passageway 80 in fluid communication with the right shaft bearings 70 permits flow of lubricating fluid from axial passageway 74 through the right shaft bearings 70 with means, not shown, provided in the pump housing for return of the lubricating fluid to the fluid reservoir 182, FIG. 4.

The manner in which the first and

second valve plates

32, 28 are constructed may best be seen by reference to FIGS. 6 to 8 shown in conjunction with an axial piston pump similar to that illustrated in FIG. 1 but utilizing conventional straight roller bearings 68b instead of the tapered roller bearings 68 utilized in the embodiment of FIG. 1. The second valve plate 28, FIG. 7, has

arcuate shaped ports 38, forming no part of the present invention, and has'an inner annular ring 198 and an outer annular ring 200 straddling the ports 38, the

rings

198, 200 being connected communicatively by radial passageways 82 with inner and outer

radial passageways

202, 204 respectively, passageways 202 communicatively connecting the inner ring 198 to the area about the first main shaft bearing 68 and passageways 204 carrying lubricating fluid radially outwardly from the outer ring 200 to the peripheral edge of the valve plate 28 and thence to the reservoir.

The first valve plate 32, FIG. 6, constructed in a similar manner to valve plate 28, has an inner ring or annular fluid channel 190 and an outer ring or annular fluid channel 192 straddling ports 40 and being communicatively connected by radially extending passageways 84, with inner radial passageways 194 provided to connect the inner ring 190 communicatively with fluid from the fluid area about the first main shaft bearing, with outer radial passageways 196 provided to connect communicatively the outer ring 192 to the peripheral edges of the first valve plate 32 and thence to reservoir.

Another embodiment of the invention is illustrated in FIG. 3 and FIGS. 9-11 wherein like parts are designated by like numerals with the addition of the sufiix a for identification. Since the basic structure shown in FIG. 3 is a conventional axial piston pump similar to the axial piston pump of FIG. 1 and designated generally by the numeral 10a, an additional description of such similar conventional features will not be given. Rather, those features, wherein the pump of FIG. 3 differs from the pump of FIG. 1 and which features embody the concepts of the present invention, will be described.

The axial piston pump 10:: includes a housing 36a having a passageway 190 which is in fluid communication with a source 180a of lubricating fluid under pressure. An antifriction bearing 68a supporting one end of pump shaft 14a is in communication with radial fluid passageways 212, 84a provided in

valve plates

28a and 32a; and the bearing 68a is also in fluid communication with a fluid chamber 192 provided about spring 26a. The chamher 192 is in fluid communication with undercut splined passageways 85a provided about the splined area 16 of the shaft by means of a passageway 194 in the housing about shaft 14.

The right hand end of cylinder block 12a is notched at points indicated by the numeral 86a and a plurality of radial openings 87a in line therewith are provided in the slipper retainer guide 60a, the openings 87a being in communication with the undercut splined passageways 85a for receipt of lubricating fluid therefrom. Annular thrust plate 56a has an inner edge 90a adjacent the slipper retainer guide 60a which edge 90a is chamfered so as to direct the flow of lubricating fluid radially outwardly from opening 86a, 87a in the slipper retainer guide 60a to flow over surface 57a of thrust plate 56a rather than through opening 89a, the openings 87a being in communication with the undercut splined passageways for receipt of lubricating fluid. The manner of operation of the lubricating structure of the axial piston pump V embodiment shown in FIGURE 3 will now be described. Conventional means 180a are provided to direct the flow of lubricating fluid under pressure from a source 182a of lubricating fluid to the axial piston pump 10a,

lubricating fluid moving through opening 190 at the left end of housing 36a with arrows indicating the direction of flow. Fluid then enters the anti-friction bearings 68:: where a portion of the flow moves radially outwardly through the valve plate passageways 82a, 84a to cool the valve plates, the fluid then being directed by conventional means, not shown, to the fluid reservoir.

Another portion of the flow of fluid from the bearings 68a moves axially to the right, as viewed in the figure into the fluid chamber 192 about spring 26a, way 194 about the shaft 14a, continuing into passageto the right through the undercut splined passageways a where the flow of fluid lubricates and cools the splined area of the shaft. The lubricating fluid continues through notches 86a in the right end of the cylinder block 12a in communication with openings 87a in the slipper retainer guide where the chamferedthrust plate 56a encourages the lubricating fluid to flow over the chamfered edge of the thrust plate rather than through opening 89a provided in the swash plate 56a. The lubricating fluid then sprays centrifugally outwardly from the slipper retainer guide openings 87a to lubricate and cool the surfaces of the slipper retainer guide 60a, slipper 24a and slipper retainer 58a; and the fluid continues to spray radially outwardly through openings, not shown, in the swash plate 44a, to lubricate trunnion bearings 50a, the fluid then being directed by conventional means, not shown, to the fluid reservoir.

The manner of construction of the valve plate and cylinder block valving surface of the embodiment of the axial piston pump illustrated in FIG. 3 is best seen by reference to FIGS. 9-11. A first valve plate or port plate 32a is illustrated in FIG. 9 pinned to the housing 36a, the plate being similar in construction to valve plate 32, FIG. 6, including inner and outer rings 190a, 192a, inner and outer radial passageways 194a, 196a and intermediate radially extending passageways 84a communicatively connecting the inner and outer rings 190a, 192a. Thus, fluid is directed radially outwardly from about the first main bearing 68a to radial passageways 194a, inner ring 190a radially extending passageways 84a and 212, FIG. 10, to the outer ring 192a and via outer radial passageways 196a to the reservoir.

The cylinder barrel 12a, FIG. 11, is provided with a valving surface 205 which is complementary to the flat valve face of valve plate 320. Cylinder barrel 12a has complementary inner and outer rings 206, 208 and arcuate ports 38a similar to the ports of the second valve those utilized in FIGS. 9-11 with the addition of the suffix c for identification. The axial piston pump, designated generally by the numeral 100, with only a portion of the pump being illustrated, includes a cylinder block 12c and a housing or end cap 360, FIG. 13. End cap 360 has arcuate shaped ports 40c therein and has a valving surface, designated generally by the'numeral 214 which is complementary to a flat valving surface 216 of the cylinder barrel 12c. The cylinder barrel 120, FIG. 14, is provided with arcuate ports 38c, inner and outer rings 206e, 208a, inner radial passageways 210e, radially extending passageways 212e, and outer radial passageways 217 communicatively connecting the inner ring 206c to the outer ring 2080 and thence to the outer periphery of the cylinder barrel and to a reservoir, not shown.

Referring now to FIG. 2, a hydrostatic transmission designated generally by the numeral 92 is shown having an axial piston pump 96 and an axial piston motor 98 coaxially arranged with a transmission housing, not shown, with a common central stationary section 100 ing pump and motor valve plates 109, 111 pinned to opposite sides thereof, the central section'100 being stationarily mounted within the transmission housing. The respective pump and

motor cylinder blocks

101, 103 of the pump and

motor

96, 98 are biased by springs, not

The pump and motor

second valve plates

102, 104 and central sechav-' motor cylintion 100 with its first valve plates 109, 111 are formed with complementary cooperating arcuate shaped inlet and outlet ports indicated respectively by the

numerals

106, 108 in the pump and motor

second valve plates

102, 104 and by the

numerals

110, 113, 115 in the center section 100 and pump and motor first valve plates 109, 111 respectively for successive communication with ports 112, 114 in cylinders 116, 118 of the pump and

motor cylinder blocks

101, 103.

Outer ball ends 120, 121 of

pistons

122, 123 in the pump and motor respectively cooperate with

swash plate assemblies

124, 126 similar to the assembly illustrated in FIG. 1 and including pump and

motor swash plates

128, 130, pump and motor thrust plates 132, 134, pump and motor slippers 136, 138, pump and

motor slipper retainers

140, 142 and pump and motor slipper retainer guides 144, 146. Ball ends of the pump and

motor pistons

122, 123 cooperate with the

swash plates

128, 130 which are pivotable in opposite directions from a minimum displacement neutral center position such as illustrated in FIG. 1 to a maximum displacement position with the

swash plate

128, 130 generally as illustrated in FIG. 2 in order to vary the displacement of the pump, as is well understood in the art. A pump drive shaft 140 is connected for rotation with an input shaft, not shown, adapted to be driven by a prime mover such as an internal combustion engine 41, FIG. 5, conventionally associated with tractors and the like.

The motor 98 is identical in construction to the pump 96 but may be somewhat larger than the pump 96 as indicated generally in FIG. 5, with the motors cylinder block 103 .splined on an output shaft 142 for rotation therewith. The

arcuate ports

108 and 115 of the motor valve plates 104 and 111 cooperate with ports 110 of the center section 100 and the

valve plate ports

113 and 106 of the

pump valve plates

102 and 109 so that the pump and motor are connected in a closed, closely cou pled hydraulic circuit.

Ball ends 121 of the motor pistons cooperate with the motor swash plate assembly 126 which is variable between a minimum allowable displacement position as illustrated in FIG. 1 and a maximum displacement position as illustrated in FIG. 2. The motor shaft 142 is connected to an output shaft, not shown, adapted to be connected to the propelling wheels of an associated vehicle such as a tractor. The

swash plate assemblies

124, 126 are controlled by means, not shown, such as by hydraulically actuatable piston assemblies, as is well known in the art.

The pump and

motor shafts

140, 142, respectively, are each provided with a central axially extending lubricant passageway 144, 146 respectively with first, second and third radially extending pump passageways 148, 150, 152 in communication with axial pump passageway 144 and corresponding to first, second and third radial passageways 76, 78, 80 as illustrated in FIG. 1. First, second and third radially extending motor passageways 154, 156, 158 in communication with the axially extending center motor passageway 146 are also provided. Additional passageways for flow of lubricating fluid are provided in the pump 96 and motor 98 similar to those provided in the pump, FIG. 1, including pump and motor splines 160, 162 which are slightly undercut providing undercut spline passageways in communication with the second or intermediate radial passageways 150, 156 and leading communicatively to cylinder block notches, not shown, and slipper retainer guide openings 164, 166 providing lubrication respectively for the pump and motor thrust plates, slippers, slipper retainers, and slipper retainer guides. The pump and motor radial passageways 148, 150, 152 and 154, 156, 158 provide lubrication for pump and motor

main shaft bearings

168, 170 and other bearings, not shown, supporting the shaft for rotation and further provide coolant for the pump and motor

second valve plates

102 and 104, first valve plates 109 and 111 and 3 center section by means of radially extending tanking grooves or passageways provided in the valve plates, being in communication with

shaft bearings

168, 170.

Conventional means 184, FIG. 5, provide a flow of lubricating fluid under pressure to the axial shaft passageways 144, 146 as by a radial opening 172 in the center section 100 in communication with the pump and motor axial passageways 144, 146 thus providing a central common fiow of lubricant and ensuring selective forced lubrication and cooling of the various wearing surfaces of the pump and motor to permit safe and efficient operation of the hydrostatic transmission at high speeds of over about 3000 to 4000 r.p.m.

Since modifications of the details of the structures as illustrated in the figures are contemplated, the invention should be limited only by the scope of the appended claims.

The invention is claimed as follows:

1. In an axial piston pump including a housing, a rotatable drive shaft extending through said housing, said shaft having first and second ends, first and second antifriction bearings supporting said shaft at its first and second ends respectively for rotation within said housing, said shaft having an outer area having a plurality of splines extending axially from a first point at an intermediate location on said shaft and extending to a second point adjacent the second end of said shaft, a cylinder block having first and second spaced ends and a plurality of axially extending splines being complementally positioned to the splines on said shaft for rotation therewith, said cylinder block having a plurality of axial cylinder bores, a plurality of pistons, each of said bores housing one of said pistons for reciprocation therein, said pistons each having a ball portion at one end thereof, said ball portions extending outwardly from said cylinder bores toward the second end of said shaft and being fitted within socketed bearing surfaces, a swash plate assembly being positioned about the shaft at its second end adjacent the socketed bearing surfaces, said bearing surfaces being positioned within said swash plate assembly for controlled reciprocation of said pistons, said housing and said cylinder block having respectively first and second complementary relatively rotatable annular valve plates to control the flow of fluid through said piston pump, said valve plates being positioned adjacent said first anti-friction bearings, said first and second valve plates having mating relatively rotating complementary face portions the improvement comprising:

means providing at least one of said first and second valve plates with radially extending fluid passageways therethrough; said passageways being adjacent said face portions,

means providing an axial shaft passageway extending axially through said rotating shaft between said first and second anti-friction bearings;

means providing said shaft with first radially extending passageways positioned adjacent said first antifriction bearings and extending communicatively between said axial shaft passageway and said first antifriction bearings;

means communicatively connecting said first anti-friction bearings and said radially extending valve plate passageways;

means providing said shaft with second radially extending passageways positioned adjacent said splined area of said shaft between said first end of said shaft and said intermediate location on said shaft,

means providing splined fluid passageways extending axially between said splined area of said shaft and said cylinder block, said splined fluid passageways communicatively connecting said second radially extending shaft passageways with said swash plate assembly;

and means providing a source of lubricating fluid under pressure to said axially extending shaft passageway,

whereby lubricating fluid under pressure is directed in a lubricating and cooling stream through said first antifriction bearings, said valve plates, about the splined area of said shaft and said swash plate assembly.

2. An axial piston pump to be operated at high speeds in a dry sump, comprising a housing; a rotating drive shaft extending through said housing, said shaft having first and second ends; first and second anti-friction bearings mounted in said housing supporting said shaft at its first and second ends respectively for rotation within said housing, said shaft having an outer area having a plurality of axially extending splines extending from a first point intermediate said first and second ends of said shaft and extending to a second point adjacent said second end of said shaft; a cylinder block splined to said shaft for rotation therewith having first and second spaced ends and a plurality of axially extending splines complemental in shape to said shaft splines and positioned for engagement with said shaft splines, said cylinder block having a plurality of axial cylinder bores; a plurality of reciprocable pistons housed individually within said bores, said pistons each having a ball portion at one end thereof extending outwardly from said cylinder bores toward a plane perpendicular to the second end of said shaft; a swash plate assembly pivotable about the second end of said shaft and positioned adjacent the ball portions of said pistons to control the axial reciprocation of said pistons, said swash plate assembly including a swash plate being pivotable about the shaft, pivoting means for pivoting said swash plate about said shaft and including a plurality of trunnion bearings supporting the swash plate, a pump slipper having a plurality of sockets f-orce fitted about the ball portions of said pistons to maintain said pistons within their respective bores, an annular thrust plate providing a bearing surface for said slipper, a slipper retainer guide splined to said shaft for rotation therewith and having a generally spherical radially outer surface, a slipper retainer to maintain the slipper in bearing position against the thrust plate, said slipper retainer being fitted about said slipper and having a generally spherical shaped radially inner surface of said slipper retainer guide for sliding movement thereon;

said pump housing and said cylinder block respectively having first and second annular valve plates positioned about said shaft between said housing and said first end of said cylinder block adjacent said first anti-friction bearings, said first and second valve plates each having complemental relatively rotating bearing surfaces, said valve plates each having a plurality of axially extending cooperating pump ports therein for fluid communication with complementary ports provided in said cylinder block bores, means providing said valve plates with a plurality of radially extending fluid passagewaysin communication with said first anti-friction bearings;

means providing an axially extending passageway through said shaft including means providing an inlet opening for receipt of a lubricating fluid under pressure;

a reservoir for lubricating fluid;

means providing a source of lubricating fluid under pressure to said inlet opening;

means providing first radially extending shaft passageways communicatively connecting said axially extending shaft passageway to said first anti-friction bearings;

means providing splined fluid passageways in said splined area of said shaft in fluid communication with said cylinder block;

a plurality of notched passageways in said cylinder block adjacent said shaft splines being in fluid communication with said axially extending splined fluid passageways;

means providing a plurality of openings in said slipper retainer guide, said openings being in communication with said notched passageways in said cylinder block for receipt of fluid under pressure from said splined fluid passageways;

means providing second radially extending passageways at an intermediate portion of said shaft immediately adjacent said splined area of said shaft between said first end of said shaft and said splined area, said second radially extending passageways communicatively connecting said axially extending shaft passageway and said splined fluid passageways;

and means providing third radially extending fluid passageways in said shaft communicatively connecting said axially extending shaft passageway to said secone anti-friction bearings;

whereby lubricating fluid under pressure is directed a rotatable drive shaft extending through said housing, a lubricant reservoir, first and second anti-friction bearings supporting said shaft at its first and second ends respectively for rotation within said housing,

means for rotating said shaft, said shaft having a splined outer area having a plurality of axially extending splines extending from an intermediate location on said shaft toward a point adajcent the second end of said shaft,

a cylinder block being positioned about said shaft, said blockhaving a plurality of axially extending splines said piston pump including a swash complementally positioned to the splines on said shaft for rotation of said cylinder block with said shaft, plurality of reciprocable pistons positioned within said axial cylinder bores for reciprocation therein, said pistons each having a ball portion at one end, said pistons being positioned with said ball end extending outwardly from said cylinder bores toward the second end of said shaft, 1

plate pivotable about the right end of said shaft, a Y plurality of trunnion bearings mounted within said housing and supporting said swash plate for pivotal movement about said shaft, said swash plate having a generally cylindrical opening facing said pistons, thrust plate being generally annular in shape and being positioned within said cylindrical opening in said swash plate, said thrust plate having a generally flat, surface facing said pistons, Y slipper positioned arcuately about said shaftan having a first and second end, said first end having means providing socket openings therein, said second end comprising a generally flat surface being generally complemental to the flat surface of said thrust plate and being adapted for sliding movement on said thrust plate, said ball ends of said pistons being fitted within said sockets of said slipper,

slipper retainer guide positioned about a portion of the second end of said cylinder block, said slipper retainer guide being splined to said shaft for rotation therewith,

1 1 a slipper retainer positioned about said slipper and being adapted to maintain said slipper in bearing contact with said thrust plate,

first and second valve plates being positioned at the first end of said cylinder block between said housing and said cylinder block, said first valve plate comprising a stationary housing plate, said second valve plate being a cylinder block plate for rotation therewith, said valve plates having intermediate abutting relatively rotating flat face portions, said valve plates being positioned adjacent said first anti-friction bear ings and being in fluid communication therewith, the improvement comprising:

means providing said shaft with an axial passageway extending through said shaft between said first and second bearings,

means providing said shift with first radial passageways positioned adjacent said first bearings and extending communicatively between said axial shaft passageway into said first bearings;

means providing each of said valve plates with a plurality of radially extending passageways adjacent said face portions communicatively connecting said first anti-friction bearings and said fluid reservoir,

means providing splined fluid passageways extending axially between said shaft splines and said complemental splines of said cylinder block;

means providing said shaft with second radially extending passageways extending communicatively between said axial shaft passageway and said splined fluid passageways at a point adjacent the valve plate end of said splined passageways;

means providing said slipper retainer guide with a plurality of openings positioned adjacent the second end of said cylinder block and being in fluid communication with said splined fluid passageways;

means providing said shaft with third radially extending passageways positioned at the second end of said axially extending passageway and extending communicatively therefrom to said second anti-friction bearings;

means providing lubricant under pressure from said reservoir to said axially extending shaft passageway, where-by lubricant under pressure flows through said first, second and third radial passageways to lubricate said shaft bearings, flowing radially outwardly in said axially extending valve grooves to cool said valve plates and returning to said reservoir,

said lubricant also flowing through said second radially extending shaft passageways to flow into said splined passageways, through said openings provided in said slipper retainer guide about said slipper and said thrust plate and radially outwardly to lubricate said trunnion bearings and returning to said reservoir.

4. The axial piston pump of claim 3 wherein said thrust plate is chamfered on an inner edge adjacent said cylinder block to encourage the flow of lubricating fluid radially outwardly over said chamfered edge about said slipper and trunnion bearings.

5. The axial piston pump of claim 3 wherein said means providing splined fluid passageways extending axially in said splined area of said shaft comprises shaft splines which are undercut to permit a flow of fluid therethrough.

6. In a hydraulic transmission including an axial piston pump, an axial piston motor, conduit means communicatively connecting said pump and said motor, said pump and motor respectively having a rotating pump and motor shaft, said shafts each havingan outer area having a plurality of axially extending splines thereon, pump and motor cylinder block being splined respectively to said pump and motor shaft splines for rotation of said cylinder blocks with said respective rotating shafts, inner pump and motor anti-friction bearings supporting inner ends respectively of said pump shaft and said motor shaft adjacent said conduit means, a pump and a motor swash plate assembly axially spaced from said conduit means, outer pump and motor anti-friction bearings supporting outer ends respectively of said pump shaft and said motor shaft, the improvement comprising:

means providing a source of lubricating fluid under pressure;

means providing axially extending passageways in said pump and motor shaft in communication with said source of lubricating fluid;

pump and motor means each providing first, second and third radial passageways connected communicatively to said pump and motor axially extending passageways, said pump and motor each having valve plates having radially extending passageways connected communicatively with said inner pump and motor anti-friction bearings, said first radially extending pump and motor passageways being in communication with said pump and motor inner anti-friction bearings;

said second radially extending pump and motor passageways being positioned respectively at intermediate portions of said pump and motor shafts and leading communicatively from said axial pump and motor passageways to said splined areas of said shaft at a position immediately adjacent the valve plate end of said splined area, means providing splined fluid passageways extending axially through said pump and motor splined areas and connected communicatively respectively to said pump and motor swash plate assemblies; said third pump and motor radially extending passageways leading respectively communicatively from said axially extending pump and motor passageways to said pump and motor outer antifriction bearings whereby lubricating fluid under pressure is directed in predetermined proportions to said pump and motor bearings, splined areas of said pump and motor shafts, pump and motor valve plates, and pump and motor swash plate assemblies.

References Cited by the Examiner UNITED STATES PATENTS 7/1919 Ferris et al 103-162 11/ 1958 Cornelius 103-202 2/1961 Douglas 103-162 2/1964 Firth et al 103-162 3/1964 Boyer a 103-162

Claims

1. IN AN AXIAL PISTON PUMP INCLUDING A HOUSING, A ROTATABLE DRIVE SHAFT EXTENDING THROUGH SAID HOUSING, SAID SHAFT HAVING FIRST AND SECOND ENDS, FIRST AND SECOND ANTIFRICTION BEARINGS SUPPORTING SAID SHAFT AT ITS FIRST AND SECOND ENDS RESPECTIVELY FOR ROTATION WITHIN SAID HOUSING, SAID SHAFT HAVING AN OUTER AREA HAVING A PLURALITY OF SPLINES EXTENDING AXIALLY FROM A FIRST POINT AT AN INTERMEDIATE LOCATION ON SAID SHAFT AND EXTENDING TO A SECOND POINT ADJACENT THE SECOND END OF SAID SHAFT, A CYLINDER BLOCK HAVING FIRST AND SECOND SPACED ENDS AND A PLURALITY OF AXIALLY EXTENDING SPLINES BEING COMPLEMENTALLY POSITIONED TO THE SPLINES ON SAID SHAFT FOR ROTATION THEREWITH, SAID CYLINDER BLOCK HAVING A PLURALITY OF AXIAL CYLINDER BORES, A PLURALITY OF PISTONS, EACH OF SAID BORES HOUSING ONE OF SAID PISTONS FOR RECIPROCATION THEREIN, SAID PISTONS EACH HAVING A BALL PORTION AT ONE END THEREOF, SAID BALL PORTIONS EXTENDING OUTWARDLY FROM SAID CYLINDER BORES TOWARD THE SECOND END OF SAID SHAFT AND BEING FITTED WITHIN SOCKETED BEARING SURFACES, A SWASH PLATE ASSEMBLY BEING POSITIONED ABOUT THE SHAFT AT ITS SECOND END ADJACENT THE SOCKETED BEARING SURFACES, SAID BEARING SURFACES BEING POSITIONED WITHIN SAID SWASH PLATE ASSEMBLY FOR CONTROLLED RECIPROCATION OF SAID PISTONS, SAID HOUSING AND SAID CYLINDER BLOCK HAVING RESPECTIVELY FIRST AND SECOND COMPLEMENTARY RELATIVELY ROTATABLE ANNULAR VALVE PLATES TO CONTROL THE FLOW OF FLUID THROUGH SAID PISTON PUMP, SAID VALVE PLATES BEING POSITIONED ADJACENT SAID FIRST ANTI-FRICTION BEARINGS, SAID FIRST AND SECOND VALVE PLATES HAVING MATING RELATIVELY ROTATING COMPLEMENTARY FACE PORTIONS THE IMPROVEMENT COMPRISING: MEANS PROVIDING AT LEAST ONE OF SAID FIRST AND SECOND VALVE PLATES WITH RADIALLY EXTENDING FLUID PASSAGEWAYS THERETHROUGH; SAID PASSAGEWAYS BEING ADJACENT SAID FACE PORTIONS, MEANS PROVIDING AN AXIAL SHAFT PASSAGEWAY EXTENDING AXIALLY THROUGH SAID ROTATING SHAFT BETWEEN SAID FIRST AND SECOND ANTI-FRICTION BEARINGS; MEANS PROVIDING SAID SHAFT WITH FIRST RADIALLY EXTENDING PASSAGEWAYS POSITIONED ADJACENT SAID FIRST ANTIFRICTION BEARINGS AND EXTENDING COMMUNICATIVELY BETWEEN SAID AXIAL SHAFT PASSAGEWAY AND SAID FIRST ANTIFRICTION BEARINGS; MEANS COMMUNICATIVELY CONNECTING SAID FIRST ANTI-FRICTION BEARINGS AND SAID RADIALLY EXTENDING VALVE PLATE PASSAGEWAYS; MEANS PROVIDING SAID SHAFT WITH SECOND RADIALLY EXTENDING PASSAGEWAYS POSITIONED ADJACENT SAID SPLINED AREA OF SAID SHAFT BETWEEN SAID FIRST END OF SAID SHAFT AND SAID INTERMEDIATE LOCATION ON SAID SHAFT, MEANS PROVIDING SPLINED FLUID PASSAGEWAYS EXTENDING AXIALLY BETWEEN SAID SPLINED AREA OF SAID SHAFT AND SAID CYLINDER BLOCK, SAID SPLINED FLUID PASSAGEWAYS COMMUNICATIVELY CONNECTING SAID SECOND RADIALLY EXTENDING SHAFT PASSAGEWAYS WITH SAID SWASH PLATE ASSEMBLY; AND MEANS PROVIDING A SOURCE OF LUBRICATING FLUID UNDER PRESSURE TO SAID AXIALLY EXTENDING SHAFT PASSAGEWAY, WHEREBY LUBRICATING FLUID UNDER PRESSURE IS DIRECTED IN A LUBRICATING AND COOLING STREAM THROUGH SAID FIRST ANTIFRICTION BEARINGS, SAID VALVE PLATES, ABOUT THE SPLINED AREA OF SAID SHAFT AND SAID SWASH PLATE ASSEMBLY.