# US 5,702,243 A · Hydraulic motor with pressure compensated end plates

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- Number: US 5,702,243 A
- Document ID: US5702243A
- Status: Granted
- Kind: A
- Application number: 08/689,322
- Filed: 1996-08-07
- Granted: 1997-12-30
- Earliest claimed: 1996-08-07
- Assignees: RHI Joint Venture
- Inventors: C. Richard Gerlach
- Web page: https://patentgrep.com/patent/US5702243A

## CPC

- F04C 15/0023: {Axial sealings for working fluid}
- F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS

## Abstract

A hydraulic motor having hydraulic pressure compensating annuli for compensating for different hydraulic forces exerted on seal plates that seal both ends of a rotor and a stator.

## Claims

### Claim 1

A hydraulic motor comprising:
a rotor having two ends;
a stator having two ends;
first and second seal plates having interior and exterior ends, the interior ends of the seal plates adjacent to the ends of the stator and the ends of the rotor;
an intake annulus defined by an interior end of a first housing and the exterior end of the first seal plate, for injecting high pressure hydraulic fluid into a radial space defined by the rotor and the stator;
an exhaust annulus defined by an interior end of a second housing and the exterior end of the second seal plate, for exhausting low pressure hydraulic fluid from the radial space defined by the rotor and the stator; and
means for asymmetrically and hydraulically compensating for different hydraulic pressures exerted on the exterior of the seal plates from the intake and exhaust annuli.

### Claim 2 (depends on 1)

The apparatus of claim 1 further comprising:
a pressure compensating annulus defined by the interior end of the second housing and the exterior end of the second seal plate, the pressure compensating annulus having a radius; and
means for hydraulically pressurizing the pressure compensating annulus to a pressure higher than a pressure exerted on the exterior end of the first seal plate along a radius equal to the radius of the pressure compensating annulus.

### Claim 3 (depends on 1)

The apparatus of claim 1 in which the seal plates are affixed to the stator.

### Claim 4 (depends on 2)

The apparatus of claim 2 in which the seal plates are affixed to the stator.

### Claim 5

A hydraulic motor comprising:
a rotor having first and second ends and radial pockets;
a stator having first and second ends;
a first seal plate adjacent the first ends of the rotor and the stator, the first seal plate defining a first aperture communicating with the radial pockets of the rotor;
a second seal plate adjacent the second ends of the rotor and the stator, the second seal plate defining a second aperture communicating with the radial pockets of the rotor, the second aperture being asymmetrical relative to the first aperture;
and a pressure-compensating annulus defined by the second seal plate and a housing, the pressure-compensating annulus communicating with the second aperture.

### Claim 6 (depends on 5)

The apparatus of claim 5 in which the radial pockets are vane pockets.

### Claim 7 (depends on 6)

The apparatus of claim 6 in which the seal plates are affixed to the stator.