Abstract:
A hydraulic motor comprising a housing having inlet and outlet ports and an access port for connecting a pressure fluid to an accessory of the motor, such as a brake. A shuttle valve integrally contained within the housing selectively communicates the pressure at one of the inlet port or the outlet port to the access port. In addition, the housing has at least two axial sections that are sealed at a parting line therebetween, and the shuttle valve is inserted through an opening in one section so that when the sections are joined, the opening is sealed at the parting line. A ring of bolts holds the sections together, and the shuttle valve is contained at least partially within the envelope formed by the ring.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/338,017 filed on Nov. 8, 2001, which is hereby incorporated herein by reference in its entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    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  
         [0003]    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.  
           [0004]    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).  
           [0005]    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  
         [0006]    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.  
           [0007]    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.  
           [0008]    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.  
           [0009]    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.  
           [0010]    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. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a side elevational view of a hydraulic motor in accordance with the present invention.  
         [0012]    [0012]FIG. 2 is an end view of the motor looking from the line  2 - 2  of FIG. 1  
         [0013]    [0013]FIG. 3 is a cross-sectional view of the motor taken substantially along the line  3 - 3  of FIG. 2.  
         [0014]    [0014]FIG. 4 is a cross-sectional view of the motor taken substantially along line  4 - 4  of FIG. 3.  
         [0015]    [0015]FIG. 5 is an end view of one housing section of the motor looking from the line  5 - 5  of FIG. 3 with the internal drive components removed for clarity.  
         [0016]    [0016]FIG. 6 is a cross-sectional view taken along the line  6 - 6  of FIG. 5. 
     
    
     DETAILED DESCRIPTION  
       [0017]    Referring now in detail to the drawings, and initially to FIGS.  1 - 3 , an exemplary hydraulic motor according to the invention is designated generally by reference numeral  10 . The exemplary motor is essentially identical to a Model TB0000AS260AAAA hydraulic motor available from Parker Hannifin Corporation of Cleveland, Ohio, except for the inclusion of the herein described shuttle valve and below-described modifications associated therewith.  
         [0018]    The motor comprises a housing  12  having a pair of inlet/outlet ports  14  and  16 , an access port  20 , and an integral shuttle valve  22  for selectively transmitting a higher pressure from one of the inlet/outlet ports to the access port. (To facilitate the description, the inlet/outlet ports  14  and  16  will be referred to hereinafter collectively as “inlet/outlet ports” and individually as the “inlet port”  14  and the “outlet port”  16 , although either port may be either an inlet or an outlet.) The pressurized fluid withdrawn or “bled” from the motor through the access port  20  may be used to control/power motor accessories, including the releasing of a brake (not shown) in conjunction with pressurized hydraulic fluid being fed into the motor.  
         [0019]    The motor  10  further comprises a drive assembly  24  within the housing  12  that uses pressurized hydraulic fluid to generate rotational motion. The illustrated drive assembly includes a gerotor set with a rotor  26  located in a central chamber  30  of the housing. The rotation of the rotor generated by the pressurized hydraulic fluid is output via a rotatable drive shaft  32  extending from the housing.  
         [0020]    The housing  12  of motor  10  may be substantially cylindrical as shown and may have a pair of mounting flanges  34  or other suitable mounting configuration. In addition, the inlet/outlet ports  14 ,  16  and the access port  20  may open to a substantially flat external face  40  of a port boss  42  protruding from one side of the housing. As shown, the inlet/outlet ports and the access port open in the same direction, a direction transverse to, and more specifically perpendicular to the longitudinal axis of the housing.  
         [0021]    The housing  12  may be formed of a plurality of longitudinally aligned axial sections. The illustrated housing includes a rear section (end cover)  50 , a drive assembly section (rotor set, manifold and commutator assembly)  52 , a wear plate  54 , and a forward section  56  (often referred to as a housing assembly in the art). Each section of the housing has an axial end face, and the sections are assembled so that respective end faces of adjacent sections abut one another along respective parting lines formed therebetween. For example, when assembled the wear plate  54  has a forward end face  60  that abuts a rear end face  62  of the forward section. The central chamber  30  in the housing referred to above extends through the drive assembly section, the wear plate and the forward section of the housing.  
         [0022]    The housing  12  also contains a hydraulic fluid circuit. Hydraulic fluid generally may move through the fluid circuit from a high pressure zone at the inlet port  14 , through the drive assembly  24 , and to a relatively lower pressure zone at the outlet port  16  in a well-known manner (or in reverse manner if the port  16  is used as the inlet and the port  14  is used as the outlet). The access port is connected to the fluid circuit via a passage containing the shuttle valve  22 . The particular arrangement of the shuttle valve and the access port provides significant advantages, as will be apparent from the following description.  
         [0023]    As shown in FIGS.  4 - 6 , the outlet port  16  may extend from the external face  40  of the port boss  42  to a first passage  70  which connects the outlet port  16  to an annular groove  71  (FIG. 5) in the face of the forward section  56 . The annular groove  71  communicates with the ends of the axial holes for bolts  92  used to secure together the sections of the motor housing. The illustrated motor is of a “wet bolt” two zone design wherein the aligned bolt holes in the wear plate and drive assembly section are oversized to provide a passage for fluid flow between the annular groove  71  and a manifold  73  at the opposite end of the motor. It is noted, however, that the invention may be practiced with other types of hydraulic motors, the illustrated motor being an example of how the principles of the invention may be applied.  
         [0024]    In the illustrated exemplary motor, a second passage  72  may connect the inlet port  14  with the central chamber  30  of the housing. The central chamber forms part of a first pressure zone wherein fluid flows between the inlet port  14  and a manifold  75  at the opposite end of the motor. The second pressure zone includes the annular groove  71 , the bolt holes and the manifold  73 .  
         [0025]    A passage  74  located between the inlet/outlet ports  14  and  16  preferably extends from the rear end face  62  of the forward section  56  to a third passage  76 . The third passage may extend from the external face of the port boss perpendicular to the axis of the housing to the central chamber. Together these latter two passages  74  and  76  allow the separate pressure zones of the motor  10  to connect. The third passage is plugged adjacent the external face of the port boss with an expansion plug  90 . The access port  20  preferably extends perpendicular to the axis of the housing, parallel to and longitudinally aligned with the third passage, to connect with the axial passage  74 . In the illustrated housing, the access port opens at a location midway between the inlet/outlet ports.  
         [0026]    The shuttle valve  22  is located in the passage  74  and defines therewith two inlets and an outlet. The shuttle valve may be mounted in the axial passage such that the outlet of the shuttle valve is aligned with the access port  20 . The inlets of the shuttle valve may be aligned with each other, with one inlet opening to the third passage  76  the other opening at the open end of the passage  74  which communicates with the annular passage  71 .  
         [0027]    In the illustrated embodiment, the shuttle valve  22  is at least partly contained with a volume defined by a peripheral arrangement of bolts  92  used to hold together the housing sections  50 ,  52 ,  54  and  56  (FIG. 2) and preferably completely contained within the sealed diameter of the motor. In the illustrated embodiment which is a “wet bolt” design as above-indicated, the bolts  92  and the holes therefor are circumferentially spaced apart and define a bolt circle within the sealed diameter that can be extended axially to define a volume in which the shuttle valve is preferably at least partly contained. More particularly, the passage for the shuttle valve can be formed on the bolt circle as shown. The sealed diameter or region of the motor in relation to the shuttle valve may be defined by a face seal  95  provided in an annular groove formed in the rear face of the forward section.  
         [0028]    In the illustrated embodiment, the shuttle valve  22  has a pressed-in valve seat  100  with an O-ring seal  102 , and a check ball  104 . The shuttle valve also has a threaded shuttle plug  106 , with a second o-ring seal  110 , to capture and limit movement of the check ball. The illustrated shuttle valve may be obtained from the Gresen Hydraulics Division of the Parker-Hannifin Corporation. As should now be apparent, the shuttle valve transmits pressure from the highest of the two pressure zones to the access port  20 . Clearly, the separate sections of the housing facilitate integration of the shuttle valve into the housing of the motor. In addition, because only a small amount of fluid is needed to transmit the pressure through the access port, the shuttle valve and associated passages can be small.  
         [0029]    It should be noted that, while the illustrated motor  10  was designed for heavy duty applications requiring low speed and high torque, the principles of the invention can be employed in pumps and motors designed for other applications. In addition, although the description herein refers primarily to motors, most motors of the type described herein may also be used as pumps driven to pressurize a fluid rather than being driven by a pressurized fluid.  
         [0030]    Although the invention has been shown and described with respect to a certain illustrated embodiment, equivalent alterations and modifications will occur to others skilled in the art upon reading and understanding the specification and the annexed drawings. In particular regard to the various functions performed by the above described integers (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such integers are intended to correspond, unless otherwise indicated, to any integer which performs the specified function (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated embodiment of the invention.