Seal assembly for hydraulic pump output shaft

Abstract

A seal assembly for a hydraulic pump is provided. The assembly includes a spacer ring, a rotor having a first side and a second side, the first side engaging the spacer ring, and a spring-loaded face seal having a face in contact with the rotor second side, where the face seal is configured to supply a force against the rotor sufficient to cause the face seal face to sealingly engage the rotor second side.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/656,286, filed Feb. 24, 2005.

TECHNICAL FIELD

The present invention relates to a hydraulic pump and, more particularly, to a seal assembly for use on an output shaft of a hydraulic pump.

BACKGROUND

A gas turbine engine may include a hydraulic pump for powering certain engine components. In one example, a hydraulic pump may be used to hydraulically power actuators that control an afterburner exhaust nozzle. The hydraulic pump includes a shaft that extends to an aircraft engine gearbox and that extends the length of the pump to communicate with a plurality of hydraulic pump components, such as pistons, gears, or vanes. A portion of the shaft, the hydraulic pump components, and hydraulic fluid are disposed within a housing.

When the aircraft engine gearbox drives the shaft, the shaft rotates within the hydraulic pump to thereby provide power to the pistons, gears, or vanes to force hydraulic fluid through the pump. As a result, power is provided to the aforementioned actuators.

To prevent leakage of the hydraulic fluid from the area along the shaft where the shaft extends through the housing, a magnetic seal has typically been used. In this regard, one section of the magnetic seal is mounted to a stator of the pump, which is typically coupled to the housing, and another section of the magnetic seal is mounted to a rotor of the pump, which is typically coupled to the shaft. The two sections of the magnetic seal attract one another to provide a leak-tight seal between the shaft and the housing.

In some cases, however, the magnetic seal may not effectively seal the hydraulic pump. For example, if the stator and rotor experience a relatively large amount of axial travel therebetween, the magnetic seal may separate which may result in loss of oil. Additionally, if metal chips are inadvertently generated inside the pump, the metal chips may interfere with the magnetic seal and separation may occur.

Accordingly, there is a need for seal assembly that is effective even when a hydraulic pump stator and a rotor experience axial travel therebetween. In addition, there is a need for seal assembly that continues to be operational, in the event metal chips are generated inside the pump. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

BRIEF SUMMARY

The present invention provides a seal assembly for a hydraulic pump. The assembly includes a spacer ring, a rotor having a first side and a second side, the first side engaging the spacer ring, and a spring-loaded face seal having a face in contact with the rotor second side, where the face seal is configured to supply a force against the rotor sufficient to cause the face seal face to sealingly engage the rotor second side.

In another embodiment, and by way of example only, a hydraulic pump is provided that includes a housing, a shaft rotationally mounted at least partially within the housing, a spacer ring mounted to the shaft, a rotor mounted to the shaft and having a first side and a second side, where the rotor first side engages the spacer ring, and a spring-loaded face seal coupled to the housing and having a face in contact with the rotor second side, the face seal configured to supply a force against the rotor sufficient to cause the face seal face to sealingly engage the rotor second side.

In still another embodiment, a seal-assembly for a hydraulic pump includes a spacer ring, a rotor having a first side and a second side, the first side engaging the spacer ring, a stator having a face in contact with the rotor second side, a seal case within which the stator is disposed, and a spring disposed within the seal case, the spring configured to supply a force against the rotor that is sufficient to cause the stator face to sealingly engage the rotor second side.

Other independent features and advantages of the preferred seal assembly will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a conventional hydraulic pump;

FIG. 2 is an exemplary seal assembly for use in the conventional hydraulic pump of FIG. 1;

FIG. 3 is an isometric view of a portion of the exemplary seal assembly depicted in FIG. 2; and

FIG. 4 is a cross sectional view of a portion of another exemplary embodiment of the seal assembly.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Before proceeding with the detailed description, it should be appreciated that the present invention is not limited to use in conjunction with a specific type of rotating machine. Thus, although the present invention is, for convenience of explanation, depicted and described as being implemented in a turbine starter, it should be appreciated that it can be implemented in numerous other machines including, but not limited to, a gas turbine engine, a hydraulic pump, a water pump, or various other chemical and industrial pumps.

Turning now to the description, a cross sectional view of a conventional hydraulic pump 100 is provided in FIG. 1. The hydraulic pump 100 may be any one of numerous types of pumps capable of producing hydraulic power. For example, the hydraulic pump 100 may be a centrifugal pump, a positive displacement pump, a reciprocating positive pump, or any other suitable type of pump. In any case, the pump 100 includes at least a housing 102, a shaft 104, and a seal assembly 200. The housing 102 contains a portion of the shaft 104 and the seal assembly 200 and includes hydraulic fluid that is pumped therethrough. The housing 102 may be a single piece, or alternatively, and as shown in FIG. 1, the housing 102 may be an assembly of multiple pieces. In an exemplary embodiment in which the housing 102 is multiple pieces, the housing 102 may include an outer housing 110 and a cover plate 112 that are coupled to one another. The cover plate 112 includes an opening 114 formed therein.

The shaft 104 is rotationally mounted within the housing 102 and extends through the cover plate opening 114. The shaft 104 has a pump section 118 and a gearbox section 120. The pump section 118 extends axially through the housing 102 and is configured to couple to various hydraulic pump components (not shown), such as pistons, gears, and/or vanes. It will be appreciated that the particular hydraulic pump components included in the housing 102 depend on the hydraulic pump type, for example, a centrifugal pump, a positive displacement pump, a reciprocating positive pump, or any other type of pump. The gearbox section 120 extends outside of the housing 102 and has an end 122 configured to couple to a gearbox (not shown).

To minimize friction that may occur when the shaft 104 rotates, a bearing assembly 124 is mounted thereto. The bearing assembly 124 includes an inner race 126, an outer race 128, and balls 130. The inner race 126 contacts the shaft 104 and rotates therewith. The outer race 128 positions the balls 130 against the inner race 126 and is coupled to a portion of the housing 102, such as, for example, to the cover plate 112.

The seal assembly 200 seals the hydraulic fluid within the housing 102 and prevents the hydraulic fluid from leaking between the shaft 104 and the cover plate 112. FIG. 2 provides a close up view of the seal assembly 200. The seal assembly 200 includes a spacer ring 202 and a face seal assembly 204. The spacer ring 202 is disposed between the shaft 104 and inner race 126 and is mounted to the shaft 104 to thereby rotate therewith. The spacer ring 202 has a retaining end 206 and a mating end 208. The retaining end 206 abuts a portion of the shaft 104 that extends radially outwardly to prevent axial movement of the spacer ring 202 along the shaft 104. The mating end 208 preferably includes two grooves 210, 212 formed thereon that are configured to mate with a portion of the face seal assembly 204, which will be described in more detail below. Although two grooves 210, 212 are depicted, it will be appreciated that fewer or more than two grooves may alternatively be employed.

With reference now to both FIGS. 2 and 3, the face seal assembly 204 includes a rotor 214, a seal case 216, and stator 218. The rotor 214 is disposed adjacent to and in contact with the spacer ring mating end 208 and is mounted to the shaft 104. The rotor 214 includes a mating face 220 and a sealing face 222. The mating face 220 preferably has two axially extending flanges 224, 226 formed thereon that correspond and engage with the two grooves 210, 212, respectively, in the spacer ring 202. Just as with the grooves 210, 212, fewer or more than two flanges 224, 226 may be alternatively employed. Moreover, although the grooves 210, 212 are shown as being formed on the spacer ring 202 and the flanges 224, 226 are depicted as being formed on the rotor 214, it will be appreciated that the grooves 210, 212 may alternatively be formed on the rotor 214 and the flanges 224, 226 may be alternatively formed on the spacer ring 202, as shown in FIG. 4.

Returning to FIG. 2, the rotor 214 may have a channel 228 formed in its inner peripheral surface 230 within which an O-ring 232 is disposed. The O-ring 232 provides a leak-tight seal between the rotor 214 and the shaft 104.

The seal case 216 is mounted to the housing 102, for example, the cover plate 112, and surrounds the shaft 104. The seal case 216 includes a cavity 234 formed therein within which the stator 218 is disposed. The stator 218 is configured to sealingly engage with the rotor sealing face 222, and in this regard, includes a sealing face 236. Preferably, a spring 238 is included that has a preload suitable for applying sufficient force against the stator 218 to thereby bias the stator sealing face 236 to sealingly contact the rotor sealing face 222. The stator 218 may be further secured within the seal case 216 by a retaining ring 240 and an O-ring 242.

During operation, the spacer ring 202 and the rotor 214 are engaged with one another via the spacer grooves 210, 212 and rotor flanges 224, 226 and both rotate with the shaft 104 with minimal axial travel along the shaft 104. The spring 238 applies force against the stator 218 so that the stator sealing face 236 and rotor sealing face 222 engage one another to thereby seal the opening 114.

There has now been provided a seal assembly that is effective even when a hydraulic pump stator and a rotor experience axial travel therebetween. In addition, the seal assembly continues to be operational, in the event metal chips are generated inside the pump.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A seal assembly for a hydraulic pump, the assembly comprising:

a spacer ring;

a rotor having a first side and a second side, the first side engaging the spacer ring; and

a spring-loaded face seal having a face in contact with the rotor second side, the face seal configured to supply a force against the rotor sufficient to cause the face seal face to sealingly engage the rotor second side.

2. The seal assembly of claim 1, wherein the rotor has an inner surface and the assembly further comprises an O-ring contacting the rotor inner surface.

3. The seal assembly of claim 1, wherein the spacer ring has an end, and the assembly further comprises:

a groove formed in the spacer ring end; and

a flange formed on the rotor first side, the flange disposed within the groove.

4. The seal assembly of claim 1, wherein the spacer ring has an end and the assembly further comprises:

a groove formed in the rotor first side; and

a flange formed on the spacer ring end and disposed within the groove.

5. The seal assembly of claim 1, wherein the spacer ring has an end, and the assembly further comprises:

a first and a second groove each formed in the spacer ring end; and

a first and a second flange each formed in the rotor first side and each disposed within the first and second grooves, respectively.

6. The seal assembly of claim 1, wherein the face seal comprises:

a seal case;

a stator disposed within the seal case, the stator having the face; and

a spring disposed within the seal case, the spring configured to supply the force against the rotor to cause the face seal face to sealingly engage the rotor second side.

7. The seal assembly of claim 1, further comprising a bearing assembly coupled to the spacer ring.

8. The seal assembly of claim 1, further comprising a shaft to which the spacer ring and rotor are mounted.

9. The seal assembly of claim 8, wherein the shaft is configured to be coupled to a gearbox.

10. A hydraulic pump, comprising:

a housing;

a shaft rotationally mounted at least partially within the housing;

a spacer ring mounted to the shaft;

a rotor mounted to the shaft and having a first side and a second side, the rotor first side engaging the spacer ring; and

a spring-loaded face seal coupled to the housing and having a face in contact with the rotor second side, the face seal configured to supply a force against the rotor sufficient to cause the face seal face to sealingly engage the rotor second side.

11. The pump of claim 10, further comprising:

an O-ring disposed between the rotor and the shaft.

12. The pump of claim 10, wherein the spacer ring has an end, and the pump further comprises:

a groove formed in the spacer ring end; and

a flange formed on the rotor first side, the flange disposed within the groove.

13. The pump of claim 10, wherein the spacer ring has an end and the pump further comprises:

a groove formed in the rotor first side; and

a flange formed on the spacer ring end and disposed within the groove.

14. The pump of claim 10, wherein the spacer ring has an end, and the pump further comprises:

a first and a second groove each formed in the spacer ring end; and

a first and a second flange each formed on the rotor first side and each disposed within the first and second grooves, respectively.

15. The pump of claim 10, wherein the face seal comprises:

a seal case;

a stator disposed within the seal case, the stator having the face; and

a spring disposed within the seal case, the spring is configured to supply the force against the rotor to cause the face seal face to sealingly engage the rotor second side.

16. The pump of claim 10, further comprising a bearing assembly disposed concentrically around the shaft, wherein the spacer ring is disposed between the bearing assembly and the shaft.

17. The pump of claim 10, wherein the shaft is configured to couple to a gearbox.

18. A seal assembly for a hydraulic pump, the system comprising:

a spacer ring;

a rotor having a first side and a second side, the first side engaging the spacer ring;

a stator having a face in contact with the rotor second side;

a seal case within which the stator is disposed; and

a spring disposed within the seal case, the spring configured to supply a force against the rotor that is sufficient to cause the stator face to sealingly engage the rotor second side.

19. The seal assembly of claim 18, wherein the spacer ring has an end, and the assembly further comprises:

a groove formed in the spacer ring end; and

a flange formed on the rotor first side, the flange disposed within the groove.

20. The seal assembly of claim 18, wherein the spacer ring has an end and the assembly further comprises:

a groove formed in the rotor first side; and

a flange formed on the spacer ring end and disposed within the groove.