Vibration dampening media in hydraulic power units

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.

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.

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.