Hydrostatic transaxle

Patent metadata

Field	Value
Publication number	US-10323737-B1
Application number	US-201715682161-A
Country	US
Kind code	B1
Filing date	Aug 21, 2017
Priority date	Mar 11, 2013
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

A transaxle for use as a drive apparatus of a vehicle is provided. The transaxle includes a main housing joined to a gear housing to enclose a transmission and a reduction gear set. The transmission includes a pump assembly and a motor assembly arranged in a parallel configuration on one side of a center section. A charge pump is contained within a pocket on an opposing side of the center section. A charge pump cover assembly secures the charge pump in the pocket and has a charge relief assembly that extends into a void volume defined by a ring gear of the gear reduction set. The gear reduction set drives an axle extending from the gear housing.

First claim

What is claimed is:

1. A drive apparatus comprising:
a housing defining a sump;
a center section disposed in the sump and comprising a first side and a second side opposite the first side;
a charge pump disposed on the second side of the center section;
a hydraulic pump assembly disposed on the first side of the center section;
a pump input shaft drivably engaged with the charge pump and with the hydraulic pump assembly;
a charge pump cover engaged with the second side of the center section, the charge pump cover comprising an external surface and an internal surface, wherein the internal surface defines a charge gallery in fluid communication with the charge pump;
a charge relief passage formed on the charge pump cover and in fluid communication with the charge gallery and with the sump; and
a charge relief assembly in fluid communication between the sump and the charge gallery, the charge relief assembly comprising a ball and a spring applying a bias force to the ball.

2. The drive apparatus of claim 1 , further comprising a hydraulic motor assembly disposed on the first side of the center section and comprising a motor cylinder block driving a motor output shaft.

3. The drive apparatus of claim 2 , further comprising an axle extending into the housing and driven by the motor output shaft, wherein a first rotational axis of the pump input shaft, a second rotational axis of the motor output shaft, and a third rotational axis of the axle lie in a common plane.

4. The drive apparatus of claim 3 , wherein the center section further comprises a bearing pocket formed in the second side, wherein the axle is supported by the bearing pocket.

5. The drive apparatus of claim 3 , wherein the common plane passes through the charge pump.

6. The drive apparatus of claim 1 , further comprising a charge relief tower extending from the external surface of the charge pump cover and in fluid communication with the charge relief passage, wherein the ball and the spring are disposed in the charge relief tower.

7. The drive apparatus of claim 6 , wherein the spring is retained in the charge relief tower by a pin.

8. The drive apparatus of claim 1 , wherein the center section further comprises a charge pump pocket formed in the second side, wherein the charge pump is disposed in the charge pump pocket.

9. A drive apparatus comprising:
a housing defining a sump;
a center section disposed in the sump and comprising a first side, a second side opposite the first side and internal porting in fluid communication with the first side and the second side;
a hydraulic pump assembly comprising a pump cylinder block disposed on the first side of the center section and driven by a pump input shaft extending into the housing and having a first rotational axis;
a charge pump located on the second side of the center section and driven by the pump input shaft;
a hydraulic motor assembly comprising a motor cylinder block disposed on the first side of the center section and in fluid communication with the pump cylinder block via the internal porting;
a motor output shaft driven by the motor cylinder block and having a second rotational axis;
an axle extending into the housing and driven by the motor output shaft, the axle having a third rotational axis, wherein the first rotational axis, the second rotational axis, and third rotational axis lie in a common plane; and
a bearing pocket formed in the second side of the center section, wherein an end of the axle is supported by the bearing pocket.

10. The drive apparatus of claim 9 , further comprising a charge pump cover engaged with the second side of the center section and disposed adjacent to the bearing pocket, the charge pump cover comprising an external surface and an internal surface opposite the external surface and defining a charge gallery, the charge gallery being in fluid communication with the charge pump and with the internal porting.

11. The drive apparatus of claim 10 , wherein the center section further comprises a charge pump pocket formed in the second side, wherein the charge pump is disposed in the charge pump pocket.

12. The charge pump of claim 11 , wherein the charge pump is a gerotor charge pump and the common plane passes through the gerotor charge pump.

13. The drive apparatus of claim 10 , further comprising a charge relief passage in fluid communication with the charge gallery and with the sump, a charge relief tower extending from the external surface and in fluid communication with the charge relief passage; and a ball and a spring disposed in the charge relief tower.

14. The drive apparatus of claim 13 , wherein the spring is retained in the charge relief tower by a pin.

15. The drive apparatus of claim 9 , further comprising a brake rotor on the motor output shaft.

16. The drive apparatus of claim 15 , wherein the motor output shaft extends entirely through the center section, and the brake rotor is disposed adjacent the second side of the center section.

17. A drive apparatus comprising:
a center section disposed in a sump defined by a housing;
a charge pump disposed on the center section;
hydraulic porting formed in the center section; and
a charge pump cover engaged with the center section to define a charge gallery in fluid communication with the charge pump and comprising:
a pressure relief passage in fluid communication with the sump and with the charge gallery;
a charge relief tower extending away from the center section; and

a charge relief assembly comprising a ball and a spring disposed in the charge relief tower, wherein the spring biases the ball toward the pressure relief passage in the charge pump cover.

18. The charge pump of claim 17 , wherein the charge pump is a gerotor charge pump.

19. The drive apparatus of claim 18 , further comprising a pump cylinder block rotatably disposed on the center section opposite the charge pump, a motor cylinder block rotatably engaged with the center section and driving a motor output shaft, and a pump input shaft drivably engaged with the charge pump and with the pump cylinder block.

20. The drive apparatus of claim 19 , wherein the hydraulic porting is in fluid communication with the charge gallery via a first check valve and a second check valve.

Assignees

• Hydro Gear Lp

Inventors

• Bonny Nathan W

Classifications

• F16H61/4139

  Replenishing or scavenging pumps, e.g. auxiliary charge pumps · CPC title

• F16H39/06 Primary

  pump and motor being of the same type · CPC title

• F16H39/14 Primary

  with cylinders carried in rotary cylinder blocks or cylinder-bearing members · CPC title