Shaft arrangement for an axial piston pump assembly

Patent metadata

Field	Value
Publication number	US-9291133-B2
Application number	US-201113330736-A
Country	US
Kind code	B2
Filing date	Dec 20, 2011
Priority date	Dec 20, 2011
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A shaft arrangement for an axial piston pump assembly to couple to a rotatable member such as a gear therewith. A shaft extends at least partially through a housing chamber of the pump about a longitudinal axis. Reciprocating pistons are disposed within the chamber radially about the shaft. A cam unit is fitted over the shaft and provides an angled camming surface to engage the pistons. Bearing assemblies are fitted over the cam unit. An adapter can be fitted over the proximal end of the cam unit. The adapter has a distal surface which may abut the bearing assembly and be axially spaced from the cam unit, and an outer radial surface to engage the rotatable member. A clamping device provides a desired clamp load path between the rotatable member, the adapter, the cam unit, the bearing assemblies and the shaft.

First claim

What is claimed is:

1. A pump assembly to couple to a rotatable member, comprising:
a pump housing having a housing chamber;
a center shaft extending at least partially through the housing chamber and rotatable about a longitudinal axis;
a plurality of reciprocating pistons disposed within the housing chamber radially about the center shaft;
a cam unit, a central bore extending through the cam unit about the longitudinal axis to receive a portion of the center shaft, a distal end having a camming surface extending radially outward to engage each of the reciprocating pistons, a proximal end opposite the distal end having a shoulder portion;
one or more bearing assemblies disposed along the cam unit between the distal and proximal ends of the cam unit;
an adapter having a central opening extending therethrough about the longitudinal axis to engage the proximal end of the cam unit, a distally facing surface having a radial flange extending radially beyond the shoulder portion of the cam unit to abut the bearing assembly, and an outer radial surface to engage to a rotatable member; and
a clamping device insertable through the central opening of the adapter and the central bore of the cam unit to fixedly attach to the center shaft.

2. The pump assembly of claim 1 , wherein the proximal end of the cam unit comprises a reduced cross-sectional area for insertion into the central opening of the adapter.

3. The pump assembly of claim 2 , wherein the proximal end of the cam unit forms a shoulder portion having a proximally facing surface, wherein the distally facing surface of the adapter and the proximally facing surface are in a confronting relationship and axially spaced from one another to form a gap therebetween.

4. The pump assembly of claim 1 , wherein a proximal end of the outer radial surface of the adapter comprises a chamfered surface configured to form a frictional interface with a tapered recess of the rotatable member.

5. The pump assembly of claim 4 , wherein the chamfered surface of the adapter extends outwardly beyond the pump housing.

6. The pump assembly of claim 1 , further comprising a shaft seal sealably engaged with the outer radial surface of the adapter between the chamfered surface and the radial flange.

7. The pump assembly of claim 1 , wherein the clamping device comprises an enlarged first end and an elongated second end extending axially from the enlarged first end about the longitudinal axis.

8. The pump assembly of claim 1 , wherein the distal end of the cam unit comprises a proximal surface facing opposite to the camming surface, the one or more bearing assemblies comprises a first bearing assembly and a second bearing assembly captured between the distally facing surface of the adapter and the proximal surface of the distal end of the cam unit.

9. The pump assembly of claim 8 , further comprising at least one spacing member disposed between the first bearing assembly and the second bearing assembly.

10. A pump assembly, comprising:
a pump housing having a housing chamber;
a pump drive shaft extending at least partially through the housing chamber and rotatable about a longitudinal axis;
a plurality of reciprocating pistons disposed within the housing chamber radially about the pump drive shaft;
a cam unit having a cam body, a central bore extending through the cam body about the longitudinal axis for receiving a portion of the pump drive shaft, a distal end having an angled camming surface extending radially outward from the cam body for engaging each of the reciprocating pistons, and a proximal end having a shoulder portion;
one or more bearing assemblies disposed along the cam body between the distal and proximal ends of the cam unit;
an adapter having a central opening extending therethrough about the longitudinal axis coupled to the proximal end of the cam unit, a distally facing surface having a radial flange extending radially beyond the shoulder portion of the cam unit abutting the bearing assembly and spaced from a proximally facing surface of the shoulder portion of the cam unit, and an outer radial surface to engage a rotatable member; and
a clamping device inserted through the central opening of the adapter and the central bore of the cam unit to fixedly attach to the pump drive shaft.

11. The pump assembly of claim 10 , wherein a proximal end of the outer radial surface of the adapter comprises a chamfered surface frictionally engaged with a tapered recess of the rotatable member, wherein the rotatable member is a gear.

12. The pump assembly of claim 10 , wherein the clamping device comprises an enlarged first end and an elongated second end extending axially from the enlarged first end about the longitudinal axis, the enlarged first end disposed outside of the rotatable member, the second end inserted through the central opening of the adapter and the central bore of the cam unit to fixedly attach to the pump drive shaft.

13. The pump assembly of claim 10 , wherein the distal end of the cam unit comprises a proximal surface facing opposite to the angled camming surface, the one or more bearing assemblies comprises a first bearing assembly and a second bearing assembly captured between the distally facing surface of the adapter and the proximal surface of the distal end of the cam unit.

14. The pump assembly of claim 13 , wherein the first bearing assembly and the second bearing assembly are tapered roller bearing assemblies, the first bearing assembly disposed distal to the second bearing assembly and are opposably tapered relative to one another, wherein the first bearing assembly is configured to withstand a greater axial load than the second bearing assembly, and the second bearing assembly is configured to withstand a greater radial load than the first bearing assembly.

15. A method of connecting a rotatable member to a pump assembly, comprising:
coupling an adapter to a rotatable member via a conical friction interface;
coupling a bearing assembly to the adapter such that a distal surface of the adapter is in an abutting relationship with the bearing assembly; and
fitting the adapter over a proximal end of a cam unit such that a gap is formed between the distal surface of the adapter, a distal end of the adapter having a radial flange extending radially beyond a shoulder portion of the cam unit and a confronting proximally facing surface of the cam unit, wherein a distal end of the cam unit comprises an angled camming surface in engagement with a plurality of pistons.

16. The method of claim 15 , further comprising engaging the cam unit to a pump center shaft of the pump assembly.

17. The method of claim 16 , further comprising coupling a clamping device to the center shaft.

18. The method of claim 17 , further comprising engaging a proximal end of the center shaft into a counterbore of the cam unit, and attaching a distal end of the clamping device to the proximal end of the center shaft, such that a desired clamp load path is formed by the rotatable member, the adapter, the bearing assembly, the cam unit, the center shaft.

Assignees

• Pickell Michael E
• Nelson Bryan E
• Avasarala Satyasai C
• Hackett David E
• Caterpillar Inc

Inventors

• Pickell Michael E
• Nelson Bryan E
• Avasarala Satyasai C
• Hackett David E

Classifications

• F04B53/006

  Crankshafts · CPC title

• F04B1/0413

  Cams · CPC title

• F02M39/02 Primary

  Arrangements of fuel-injection apparatus to facilitate the driving of pumps; Arrangements of fuel-injection pumps; Pump drives · CPC title

• F04B9/042

  the means being cams · CPC title

• Y10T29/49236

  Fluid pump or compressor making · CPC title