Power plants – Pressure fluid source and motor – Condition responsive control of motive fluid flow
Reexamination Certificate
2002-11-08
2004-12-07
Lazo, Thomas E. (Department: 3745)
Power plants
Pressure fluid source and motor
Condition responsive control of motive fluid flow
C418S061300
Reexamination Certificate
active
06826909
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a hydraulic motor and, more particularly, to a hydraulic motor with a gerotor drive assembly and integral shuttle valve useful with a brake assembly.
BACKGROUND OF THE INVENTION
A hydraulic motor can convert pressurized fluid flow into torque and speed for transferring rotational motion to a desired piece of machinery. A common type of hydraulic motor includes a gerotor set having an inner rotor “gear” received in an outer stator “gear.” The stator has internal teeth or “vanes” extending radially inwardly and the rotor has one less external “tooth” or lobe extending radially outwardly. The rotor teeth remain in contact with the stator vanes as the rotor moves relative to the stator, and the resulting continuous multi-location contacts create fluid pockets that sequentially expand and contract as fluid is supplied and exhausted from the fluid pockets in a timed relationship.
As the pressurized fluid circulates through the fluid pockets, the pressurized fluid produces shaft rotation. Conversely, a gerotor set can be used in a pump such that shaft rotation can be used to produce fluid pressure, and thus a gerotor set can be used in a motor. A gerotor motor can provide a combination of compact size, low manufacturing cost, and high torque capacity thereby making it a popular choice for heavy duty applications requiring low speed (e.g., about 1000 rpm or less) and high torque (e.g., about 15,000 in-lb or more).
In the past, a variety of external valve components were connected to hydraulic motors for various purposes, either directly attached to the motor or connected remotely by hydraulic lines. These valve components have included shuttle valves. A common application is to connect a supply pressure to a brake normally biased to a braking condition for releasing the brake in conjunction with the supply of fluid power to the hydraulic motor. These valve component designs have been relatively heavy and bulky.
SUMMARY OF THE INVENTION
The present invention provides a hydraulic motor having an integral shuttle valve that, when compared to the conventional hydraulic motor and external valve arrangement, is lighter, uses fewer components, and is less bulky and more compact. Specifically, the present invention provides a hydraulic motor having a shuttle valve contained within the housing of the motor to provide pressure from the fluid circuit to an access port. Such a motor may be particularly useful with a brake, whereby the access port may provide a pressure in conjunction with the supply of hydraulic fluid to a motor to release a brake and allow the motor to rotate.
More particularly, the present invention provides a hydraulic motor having a housing, a chamber contained within the housing, and a drive assembly. The drive assembly includes a rotor located in the chamber and a drive shaft extending from the housing. The housing has inlet and outlet ports connected to a fluid circuit in the housing. The fluid circuit also is connected to an access port by a shuttle valve contained within the housing. The shuttle valve selectively transmits a relatively higher pressure from one of the inlet and outlet ports to the access port. Preferably, the shuttle valve is contained within the sealed diameter or region of the motor containing the fluid circuit.
The present invention also provides a hydraulic motor wherein the housing has at least two axial sections meeting at a parting line, and wherein the inlet and outlet ports open to an external face of the housing. In this embodiment, the shuttle valve is located in a passage in one of the axial sections, and the passage opens to the parting line between the sections of the housing so as to be internal to the housing when the sections of the housing are joined together.
The present invention further provides a hydraulic motor wherein the housing sections are held together by a peripheral arrangement of bolts. In this embodiment, the peripheral arrangement of bolts define a volume therebetween, and the shuttle valve is mounted at least partially within the volume defined by the peripheral arrangement of bolts. The bolts may be arranged in a circular fashion to define a cylindrical volume in which the shuttle valve is at least partly contained.
These and other features of the invention are fully described and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative embodiments of the invention, these embodiments being indicative of but a few of the various ways in which the principles of the invention may be employed.
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Auxiliary valves VV&Lgr; Shuttle valve. Catalog No. 9129 8602-06 (USA). Jan. 1998.
Lazo Thomas E.
Parker-Hannifin Corp.
Renner , Otto, Boisselle & Sklar, LLP
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