Patent Publication Number: US-2002006345-A1

Title: Hydraulically retractable hydraulic motor

Description:
SPECIFICATION  
     [0001] This application is a continuation of U.S. Pat. App. Serial No. 09/504,988. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] The present invention is a method and apparatus for hydraulically disengaging an output shaft of a hydraulic motor. In particular, the hydraulic motor includes a longitudinal movable output shaft which may be moved hydraulically for allowing the driven mechanism to rotate without interference from the hydraulic motor.  
       [0003] In hydraulic equipment, and especially mobile hydraulic equipment, it is often necessary and/or desirable to disengage the hydraulic motor from the mechanism it is driving so as to free wheel the mechanism. An example of this is a hydraulic motor which is connected to the wheels of a mining machine and used to propel the mining machine. When it becomes necessary to tow the mining machine the hydraulic motor must be disengaged from the drive train so the machine will roll freely. Another example is a scissor-lift used to load and unload aircraft. It is typically driven with a hydraulic motor connected to its drive train. When this vehicle requires towing, it is again necessary to disengage the motor from the drive train. Another example is a knuckle-boom loader which is used in the harvesting of timber. When it is in the woods, it is propelled by a hydraulic motor connected to its drive train. When it is transported to another job site, the hydraulic motor must be disconnected to allow the knuckle-boom loader to be towed.  
       [0004] Yet still another example is when a hydraulic motor is used to drive a winch. It is often necessary to disengage the motor in order to free wheel cable off the winch. Disengaging the hydraulic motor in the above examples is often accomplished by unbolting and physically removing the motor, building an elaborate slide which will slide the motor out of engagement, or using an expensive clutch between the motor and the drive train which can disengage the motor. Such disengagement may also be accomplished by hand, as set forth in U.S. Pat. No. 5,261,801. However, the art lacks a means of hydraulically engaging and disengaging a hydraulic motor.  
       SUMMARY OF THE INVENTION  
       [0005] An object of the present invention is to provide an automated means of engaging and disengaging a hydraulic motor from an external rotary load. Another object of the invention is to provide a means of easily retrofitting prior art hydraulic motors with automated means of engaging and disengaging the motor. Another object of the present invention is to provide a non-torque bearing hydraulic actuator.  
       [0006] There is provided a retractable shaft motor assembly comprising an axially moveable drive shaft, a retractable rod in communication with the drive shaft, an actuator in communication with the retractable rod, and a motor positioned between the drive shaft and the actuator. The actuator rod may be fixedly connected to the drive shaft. The actuator rod may be rotatably connected to the actuator. The actuator rod may be slidably positioned along an axis of the motor. The retractable actuator rod may be non-torque-bearing. The motor may be a hydraulic motor.  
       [0007] There is also provided a hydraulically retractable shaft motor comprising a motor, the motor having a longitudinal axis, an axially moveable output shaft, the output shaft having an interface for selectively engaging the motor, and an axial hydraulic actuator assembly connected to the output shaft. The hydraulic actuator assembly may comprise a cylinder, a piston, and an actuator rod. The motor may be a hydraulic motor comprising a rotor and a stator, and the hydraulic actuator assembly may comprise a non-torque bearing actuator rod. The actuator rod may be non-torque bearing. The actuator rod may be rotatably connected to the piston. The motor and the output shaft may have longitudinal coacting splines.  
       [0008] There is also provided a method of disengaging a hydraulic motor having a rotor, a stator, and a longitudinally moveable output shaft in selective communication with an external rotary load, comprising hydraulically and longitudinally moving the output shaft relative to the rotor whereby the output shaft disengages from the external load. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a cross-sectional view of a disengaged, hydraulically-engageable hydraulic motor exemplary of the present invention.  
     [0010]FIG. 2 is a cross-sectional view of an engaged, hydraulically-engageable hydraulic motor exemplary of the present invention.  
     [0011]FIG. 3 is a cross-sectional view of an alterative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0012]FIG. 1 depicts a cross-sectional view of a disengaged hydraulically engageable hydraulic motor  10  exemplary of the present invention. The hydraulic motor  10  comprises a rotor  12  and stator  14 . Output shaft  16  exhibits a dog-face clutch  17  axially and rotatably attached to retractable spline portion  20 . Motor shaft  22  is integral with rotor  12  and exhibits splines  24 . Splines  24  slideably coact with splines  26  of output shaft  16 . Actuator rod  28  is fixed to output shaft  16  by bolt  30  and, whereby actuator rod  28  rotates with output shaft  16 .  
     [0013] Actuator rod  28 , and in turn output shaft  16 , are moved axially by actuator piston assembly  31 . Actuator piston assembly  31  comprises actuator piston  32 , which rotatably communicates with actuator rod  28  via thrust flange assembly  34 . Thrust flange assembly  34  comprises thrust flange  36 , thrust bearings  38 , thrust washer  40 , and snap ring  42 . Thrust flange assembly  34  enables actuator rod  28  to rotate relative to piston  32 . Thrust flange assembly  34  is connected to the actuator rod  28  by bolt  33 .  
     [0014] Actuator piston assembly  31  is driven axially within cylinder  44  by alternating hydraulic fluid pressures through hydraulic fluid passageways  46  and  48 . Hydraulic fluid passageway  46  injects hydraulic fluid into and bleeds hydraulic fluid from chamber  50 , and hydraulic fluid passageway  48  injects hydraulic fluid into and bleeds hydraulic fluid from chamber  52 . Actuator piston seals  54  prevent communication of hydraulic fluid between chamber  50  and chamber  52 .  
     [0015] Actuator rod main rotary seal  56  in seal plate  58  prevents communication of hydraulic fluid from the front hydraulic cavity  52  to the motor case  60 . Actuator rod seal  61  prevents leakage of case fluid.  
     [0016] Actuator piston assembly  31  and actuator rod  28  selectively drive output shaft  16  and attached dog-face clutch  17  and dog teeth  18  in and out of engagement with dog-face clutch teeth  72  of load shaft  70 . Once engaged, motor shaft  22  rotates load shaft  70 . Actuator rod  28  is not imparted the full torque of the motor shaft  22 , because the output shaft  16  communicates directly with the motor shaft  22 , and because actuator rod  28  rotates relative to the actuator piston assembly  31 .  
     [0017] To engage hydraulic motor  10  of the present invention, hydraulic fluid is injected through hydraulic fluid passageway  46  into chamber  50 , while simultaneously venting any hydraulic fluid in chamber  52  through passageway  48 , whereby shaft  16  forces dog-face clutch  17  into engagement with dog-face clutch  70 . To disengage the hydraulic motor  10 , the foregoing hydraulic fluid flow is reversed.  
     [0018]FIG. 2 depicts the motor of FIG. 1 in an engaged position, with splines  24  and  26  coacting with each other, and dog-face clutch teeth  18  engaged with dog-face clutch teeth  72 .  
     [0019]FIG. 3 depicts an alternative embodiment of the present invention, in which  25  output shaft  16  comprises an engagement mechanism  64  exhibiting external splines  66 . Engaged position  68  is shown in shadow. External load shaft  74  exhibits internal splines  76  which are selectively engageable with splines  66 . The engaged position of splines  66  with splines  76  is shown in shadow by position  68 .  
     [0020] The foregoing are merely examples of the invention. One of ordinary skill in the art will appreciate that several embodiments of the invention may be devised within the scope of the claims.