Patent Publication Number: US-6991398-B2

Title: Tool coupler

Description:
FIELD OF THE INVENTION 
   The present invention is directed to a tool coupler using a single slidably mounted hydraulic cylinder to move two locking pins to lock a coupler frame to an attachment frame. 
   BACKGROUND OF THE INVENTION 
   Tool couplers for work vehicles are well known in the art. These couplers allow an operator to quickly switch from one tool attachment to another to perform a different operation. Tool couplers comprise an attachment frame mounted to the attachment and a coupler frame mounted to the work vehicle. The coupler frame may be provided with catches that engage hooks on the attachment frame. To lock the attachment frame to the coupler frame, slidable locking pins on the coupler frame are used to engage receiving apertures in the attachment frame. 
   U.S. Pat. No. 5,692,850 discloses a tool coupler wherein two locking pins are positioned by extending and retracting a hydraulic cylinder. The hydraulic cylinder is mounted to a coupler frame. The hydraulic cylinder has two piston rods having locking pins that engage receiving apertures on an attachment frame. The barrel of the hydraulic cylinder is fixedly mounted to the coupler frame. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a tool coupler that uses a single slidably mounted hydraulic cylinder to couple and uncouple two locking pins. 
   The tool coupler comprises a coupler frame mounted to the work vehicle and an attachment frame mounted to the tool. The attachment frame is provided with two downwardly opening hooks that engage two transverse catches located on the coupler frame. The coupler frame is provided with two transversely arranged locking pins and the attachment frame is provided with two transversely arranged receiving apertures, for locking the coupler frame to the attachment frame. Both locking pins are actuated by a single double acting hydraulic cylinder that is in line with the locking pins. The hydraulic cylinder has an extended coupled position, wherein the locking pins are extended to engage the receiving apertures, and a retracted uncoupled position, wherein the locking pins are withdrawn from the receiving apertures. 
   The hydraulic cylinder is slidably mounted on the coupler frame. The hydraulic cylinder is provided with a piston rod having the first locking pin and a barrel end having the second locking pin. The piston rod is extended from and retracted into the barrel end. Both locking pins are slidably positioned in bosses mounted to the coupler frame. Each boss is provided with a through passage for receiving and guiding the respective locking pin. The pin is received in the boss when the hydraulic cylinder is in its extended coupled position and its retracted uncoupled position. The coupler frame and the hydraulic cylinder are provided with limiters which limit the sliding movement of the piston rod and the barrel end of the hydraulic cylinder relative to the coupler frame. The piston rod limiter limits the sliding movement of the piston rod relative to the coupler frame and the barrel end limiter limits the sliding movement of the barrel end relative to the coupler frame. Each limiter comprises a slot formed in the coupler frame and a pin extending from the respective portion of the hydraulic cylinder that engages the slot. The slots are parallel to the longitudinal axis of the hydraulic cylinder and are sized in the transverse direction to keep the locking pins in the bosses. Therefore, as the locking pins are extended and retracted the locking pins maintain contact with and are guided by the bosses. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a work vehicle having a tool coupler. 
       FIG. 2  is an enlarged side view of the tool coupler. 
       FIG. 3  is a rear view of the tool coupler with the hydraulic cylinder in its extended coupled position. 
       FIG. 4  is a rear view of the tool coupler with the hydraulic cylinder halfway between its extended locking position and its retracted uncoupled position. 
       FIG. 5  is a rear view of the tool coupler with the hydraulic cylinder in its retracted uncoupled position. 
   

   DETAILED DESCRIPTION 
   The work vehicle illustrated in  FIG. 1  is a four wheel drive loader  10 . The loader  10  comprises a front frame portion  12  and a rear frame portion  14  that are pivotally coupled to one another by a vertical articulation joint  16 . Each frame portion is provided with a pair of drive wheels  18 . The rear frame portion  14  houses an engine and transmission that drives the wheels  18 . A telescoping drive shaft, not shown, extends across the articulation joint  16  to power the front pair of wheels  18 . The loader  10  is steered by pivoting the frame portions  12  and  14  about the articulation joint  16  by steering hydraulic cylinders  20 . The operation of the loader is controlled by an operator located in an operator&#39;s cab  22 . 
   The front frame portion  12  is provided with a boom  24  that is pivotally attached to the front frame portion  12  at pivot  26 . Boom hydraulic cylinders, not shown, lift and lower the boom  24  relative to the front frame portion  12 . A tool in the form of a bucket  28  is pivotally coupled to the boom  24  at pivot  30 . The position of the bucket  28  relative to the boom  24  is controlled by bucket linkage  32  and bucket hydraulic cylinder  34 . Although the present invention is disclosed as being mounted on a four wheel drive loader  10  it can also be used on skid steer loaders, backhoe loaders, crawlers and other work vehicles. 
   The bucket  28  is mounted to the boom  24  by a tool coupler  40 . The tool coupler  40  allows other tools, for example material handling forks, or jib booms, or snow blowers, or other tool attachments to be readily coupled to the loader  10 . The tool coupler comprises an attachment frame  42  mounted to the bucket  28  and a coupler frame  44  mounted to the boom  24  of the loader  10 . The attachment frame  42  comprises two downwardly opening hooks  46  located above two transversely arranged receiving apertures  48  and  49 . 
   The coupler frame  44  is pivotally mounted to the boom  24  at pivots  30  and to the bucket linkage at pivot  50 . The coupler frame  44  is also provided with two transversely arranged cylindrical catches  52  that are used to engage downwardly opening hooks  46  of the attachment frame  42 . The coupler frame  44  is locked to the attachment frame  42  by transversely arranged locking pins  54  and  55  that engage the receiving apertures  48  and  49  on the attachment frame  42 . The position of the locking pins  54  and  55  is controlled by a single hydraulic cylinder  56 . The hydraulic cylinder  56  is a double acting hydraulic cylinder that is slidably mounted on the coupler frame  44 . The hydraulic cylinder  56  has an extended coupled position and a retracted uncoupled position. 
   The hydraulic cylinder  56  has a piston rod  58  that is slidably received in the barrel end  60 . By using pressurized hydraulic fluid, the piston rod  58  is extended from and retracted into the barrel end  60 . The piston rod  58  is provided with the second locking pin  55  and the barrel end  60  is provided with the first locking pin  54 . The locking pins  54  and  55  are received and guided by bosses  62  mounted to the coupler frame  44 . Each of the bosses  62  have a through passage into which the respective locking pin is received and guided. As shown in  FIGS. 3 ,  4  and  5  the locking pins  54  and  55  are always in contact with the bosses  62  whether the hydraulic cylinder  56  is fully extended or fully retracted. 
   As the hydraulic cylinder  56  is slidably mounted on the coupler frame  44 , it is necessary to limit the relative movement of the piston rod  58  and the barrel end  60  relative to the coupler frame  44 . The coupler frame  44  is provided with a piston rod limiter  64  and a barrel end limiter  66  that limits the sliding movement of the piston rod  58  and barrel end  60 , respectively. The piston rod limiter  64  comprises a piston rod slot  72  formed in the coupler frame  44  and a piston rod pin  74  that rides in the slot  72 . Similarly, the barrel end limiter  66  comprises a barrel end slot  68  formed in the coupler frame  44  and a barrel end pin  70  that rides in the slot  68 . As the hydraulic cylinder  56  is retracted from its extended coupled position to its retracted uncoupled position, the piston rod  58  and the barrel end  60  may not move in unison with one element moving more than the other. The limiters  64  and  66  allow the elements to move a defined amount before stopping the respective element&#39;s movement relative to the coupler frame  44 . The slots  68  and  72  are parallel to the longitudinal axis of the hydraulic cylinder  56  and are sized to maintain the locking pins  54  and  55  in their respective bosses  62 . 
   Having described the illustrated embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.