Title:
VIBRATION DAMPENING MEDIA IN HYDRAULIC POWER UNITS
Kind Code:
A1


Abstract:
A hydraulic power unit that uses a quantity of media within a cavity adjacent to and surrounding a hydraulic assembly in the housing of the hydraulic power unit to reduce the overall noise of the unit. Additionally, the cavity either seals the media from the moving parts of the hydraulic assembly or isolates the media from the moving parts of the hydraulic assembly to ensure damage to the hydraulic assembly does not result.



Inventors:
Gandrud, Michael D. (Ames, IA, US)
Application Number:
11/679280
Publication Date:
10/22/2009
Filing Date:
02/27/2007
Assignee:
SAUER-DANFOSS INC. (Ames, IA, US)
Primary Class:
Other Classes:
417/415
International Classes:
F04B3/00
View Patent Images:
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Primary Examiner:
LOPEZ, FRANK D
Attorney, Agent or Firm:
ZARLEY LAW FIRM P.L.C. (DES MOINES, IA, US)
Claims:
1. A hydraulic power unit comprising: a housing having a hydraulic assembly with reciprocating pistons disposed therein; at least a first cavity disposed within the housing adjacent the hydraulic assembly; a quantity of media within the cavity to reduce noise produced by the hydraulic assembly; wherein the cavity is enclosed by the housing, a tube that surrounds the hydraulic assembly and a swashplate of the hydraulic assembly so that the media is isolated from moving components of the hydraulic assembly.

2. The hydraulic power unit of claim 1 wherein the hydraulic assembly is actuated by an input shaft disposed through a cylinder block that houses the reciprocating pistons.

3. The hydraulic power unit of claim 1 wherein the hydraulic assembly is actuated by an electric motor.

4. The hydraulic power unit of claim 1 wherein the tube has at least one opening therein to provide fluid communication between oil of the hydraulic assembly and the media.

5. The hydraulic power unit of claim 1 further comprising a fill plug disposed through the housing and into the cavity to provide access to the cavity.

6. 6.-7. (canceled)

8. The hydraulic power unit of claim 1 wherein the quantity of media partially fills the first cavity.

9. The hydraulic power unit of claim 1 wherein the quantity of media completely fills the first cavity.

10. The hydraulic power unit of claim 1 wherein the media comprises a plurality of clean particles.

11. The hydraulic power unit of claim 1 wherein the media is selected from the group consisting of glass spheres, clean stone gravel, crushed hard rock, granite chips, sand, recycled glass and metal, polymer or ceramic particles.

12. The hydraulic power unit of claim 4 wherein the opening is of size and shape to isolate media from moving components of the hydraulic assembly.

13. A hydraulic power unit comprising: a housing having a hydraulic assembly with reciprocating pistons disposed therein; at least a first cavity disposed within the housing adjacent the hydraulic assembly; a quantity of media within the cavity to reduce noise produced by the hydraulic assembly; and a second cavity having at least one interconnected circuit board used to control the hydraulic power unit wherein a quantity of media is also disposed within the second cavity.

Description:

BACKGROUND OF THE INVENTION

This invention relates to hydraulic power units. More specifically, this invention relates to a hydraulic power unit that uses media therein to dampen noise of the unit.

Operators of equipment and vehicles that use various hydraulic power units such as hydraulic pumps, hydraulic motors, hydraulic rotary actuators, hydraulic valves and the like desire to reduce the noise levels that are produced by such units. Specifically, the government continues to require that noise levels in work settings produced by forklifts, backhoes, and the like that use hydraulic power units be minimized. Excess noise over long periods of time can cause workers to suffer from hearing loss, ringing ears, and the like.

Therefore, a principal object of the present invention is to provide a hydraulic unit that dampens the noise produced by a hydraulic assembly within the hydraulic power unit.

Another object of the present invention is to provide a means that dampens the overall noise produced by a hydraulic unit without contaminating fluids or damaging moving parts within the hydraulic power unit.

These and other objects, features or advantages of the present invention will become apparent from the specification and claims.

BRIEF SUMMARY OF THE INVENTION

A hydraulic power unit comprising a housing having a hydraulic assembly disposed therein. Additionally disposed within the hydraulic power unit is at least a first cavity adjacent and surrounding the hydraulic assembly. Within the cavity is a quantity of media that acts to reduce or dampen noise produced by the hydraulic assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a hydraulic power unit having a cavity in communication with a hydraulic assembly;

FIG. 2 is a sectional view of a hydraulic power unit having a cavity sealed from a hydraulic assembly.

FIG. 3 is a sectional view of a hydraulic power unit having a cavity in communication with a hydraulic assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-3 provide three embodiments of a hydraulic power unit 10 that dampens noise within the unit. FIG. 1 shows an embodiment of the hydraulic power unit 10 having a housing 12 that contains a hydraulic assembly 14 therein. The hydraulic assembly 14 of FIG. 1 has an input shaft 16 disposed through a cylinder block 18 having pistons 20 disposed therein reciprocating against a swashplate 22 for the purpose of displacing hydraulic fluid.

In this embodiment a cavity 24 is disposed within the housing 12 adjacent and surrounding the hydraulic assembly 14. The cavity 24 is enclosed by the housing 12, a stove pipe tube 26 that surrounds the hydraulic assembly 14 and by swashplate 22 that is disposed within cavity 24. The stovepipe tube 26 has a plurality of openings 28 therein such that oil associated with the hydraulic assembly can communicate between the cavity 24 and the hydraulic assembly 14. Within the cavity 24 is a quantity of media 30.

In FIG. 1 the media 30 is shown as completely filling the cavity 24 but in an alternative embodiment the media 30 could partially fill the cavity 24. In this embodiment because oil associated with the hydraulic assembly 14 is in communication with the cavity 24 the media 30 must comprise a plurality of clean particles or clean media. This clean media includes but is not limited to glass spheres, clean stone gravel, washed crushed granite chips or the like. Additionally, the openings 28 and media 30 are both of size and shape such that the media 30 is unable to be disposed through the openings 28 so that the media 30 is isolated from the moving components of the hydraulic assembly 14.

The housing 12 additionally comprises a fill plug 32 that allows an operator to fill the cavity 24 with a quantity of media 30. Thus, once the media 30 is within cavity 24 the media acts to buffer or dampen the noise created by the hydraulic assembly 14 similar to how a bell that is partially filled with sand does not ring. Consequently, less noise is produced by the hydraulic power unit 10.

FIG. 2 shows an alternative embodiment of hydraulic power unit 10. In this hydraulic power unit the stove pipe tube 26 and swashplate 22 do not comprise part of cavity 24 and instead an inner wall 34 seals the cavity 24 from the hydraulic assembly 14. Thus, because the cavity 24 is no longer in communication with the hydraulic assembly 14 the media 30 no longer needs to comprise clean particles. Consequently media 30 can comprise but is not limited to sand, gravel, crushed recycled glass, metal, polymer, or ceramic particles, glass marbles and the like. Similar to the embodiment seen in FIG. 1 wherein the openings 28 in stove pipe tube 26 are of size and shape to prevent the media 30 from contacting hydraulic assembly 14, by sealing the cavity 24 media 30 again is isolated from the moving parts of the hydraulic assembly 14 preventing potential damage to the hydraulic assembly 14.

FIG. 3 shows yet another embodiment of the present invention. In this embodiment the hydraulic assembly 14 is powered by an electric motor 36 having a stator 38, stator winding 40 and rotor 42 as is known in the art. In this embodiment, as in the embodiments of FIGS. 1 and 2, the cavity 24 is adjacent to and surrounds the hydraulic assembly 14. In this embodiment the cavity 24 is enclosed by housing 12 and a strainer 44 that has a plurality of strainer openings 46 therein that allow fluid communication between the hydraulic assembly 14 and cavity 24 similar to that shown in FIG. 1. Again, the openings 46 within strainer 44 are of size and shape and the media 30 therein additionally are of size and shape to isolate the media 30 within the cavity 24 from the moving parts of the hydraulic assembly 14 to prevent damage.

In this embodiment a second cavity 48 is provided that is considered a control circuitry cavity. The control circuitry cavity 48 has a cover member 50 and the second cavity 48 houses at least one interconnected circuit board 52. As with the first cavity 24 the second cavity 48 additionally houses a quantity of media 54 that may represent any of the media previously discussed. Thus, the media 54 in the second cavity 48 similarly acts to dampen noise produced by circuit board 52.

Disclosed are a plurality of embodiments of hydraulic units that use a first cavity 24 adjacent to a hydraulic assembly 14 to reduce the overall noise of the hydraulic power unit. Additionally, by using media 30 that is of size and shape that cannot be disposed through openings 28 of stove pipe tube 26, strainer 44 or by completely sealing the cavity 24 from the hydraulic assembly, damage to the hydraulic assembly 14 is minimized. Specifically, one skilled in the art would not think to use media and specifically granule type media within a hydraulic power unit as such a media could potentially cause major damage to the unit 10 and/or contaminate fluid within the unit. Thus, at the very least, all of the stated objectives have been met.

It will be appreciated by those skilled in the art that other various modifications could be made to the device without the parting from the spirit in scope of this invention. All such modifications and changes fall within the scope of the claims and are intended to be covered thereby.