Abstract:
A quick coupler for mounting implements on excavators has an upwardly facing set of recesses for engaging one mounting pin and a laterally facing set of recesses for engaging the other mounting pin on the implement. A freely rotatable latch closing the lateral recesses is provided with two locking mechanisms, both of which provide positive metal to metal lock.

Description:
This patent application is a continuation of application Ser. No. 09/049,179 filed on Mar. 27, 1998, now abandoned and incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a connector for attaching implements to mobile construction equipment and the like and more particularly to a quick coupler allowing convenient interchangeability of implements on construction equipment. 
     Heavy equipment is used at construction sites, scrap yards, in roadwork, railroad maintenance, mines, at demolition sites, and elsewhere. Such equipment includes smaller tractors with backhoes, large excavators and other pieces of equipment. Often, excavators and backhoes have a boom attached to the body of the piece of equipment and a stick attached to the end of the boom. An implement such as a digging bucket, an impact hammer, an earth compactor, or another piece of equipment is then attached at the end of the stick. The implement at the end of the stick is often attached by means of a hinge pin connected to the stick and the implement. Additionally, a hydraulic cylinder connected to the stick is also connected to the implement through a link by means of a link pin. This allows the operator of the equipment to position the implement with the boom and stick and also rotate the implement about the end of the stick by means of the stick hydraulic cylinder. 
     A particular piece of construction equipment may be put to several different uses at the same job site. It may be used with an impact hammer to break-up concrete or rocks. At a different time at the same site, it will be used with a bucket to excavate a trench. Thereafter, the same piece of equipment may be used with a compactor implement when the trench is refilled. In order to efficiently use this versatility, the changing of implements at the end of the stick should be a relatively quick operation. To this end, numerous quick coupler attachments have been provided in the past. Generally, such quick couplers are attached to the stick and stick cylinder link of the piece of equipment. Recesses are provided on the open face of the quick coupler which can engage pins on the implement to be attached. Hydraulic, spring and/or other mechanisms are then used to grasp the pins on the implement. 
     Such prior art quick couplers sometimes employ hydraulic cylinders to directly drive a closure member around a pin. Other prior art quick couplers use a heavy spring to drive a closure member around a pin. In some instances, the force on the implement in use acts directly against the force of the hydraulic cylinder or spring retaining the implement. Other units require extensive hand manipulation in moving or cocking engagement members. Sometimes such hand manipulations require a good deal of effort as construction equipment is heavy and the quick coupler must therefore be robust. Moreover, the forces applied on construction equipment are often very large also requiring robust connectors, springs or hydraulic cylinders. The construction, demolition, mining, and other environments in which such equipment are used are usually gritty, open to the elements and very hard on equipment. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a quick coupler which does not require heavy springs directly biasing a pin grasping member into a closed position or a hydraulic cylinder exerting a large closure force on a pin grasping member. 
     In accordance with the present invention, there is provided a quick coupler comprising recesses which engage the upper mounting pin on an implement, recesses which engage the lower mounting pin on an implement, a movable latch which is positioned by contact with the pins on the implement only and a gate fixing the latch in the closed position when attached to an implement. 
     Further in accordance with the invention, the recesses on the quick coupler comprise one set of U-shaped recesses with the opening of the U facing in the direction of the plane defined by the two pins on the implement and the second set of U-shaped recesses with the opening of the U facing perpendicular to the plane defined by the two pins on the implement with the latch engaging the pin in the second set of recesses. 
     Still further in accordance with the invention, the latch comprises a hook shaped surface with the short leg of the hook forming a closure portion and the long leg of the hook forming an engagement portion and a pin of the implement retained between the closure portion and engagement portion when the latch is in the closed portion. 
     Still further in accordance with the invention, the latch closure portion engages the lower mounting pin on the implement and the closure portion is shaped so that the lower mounting pin may push by the closure portion when entering the appropriate recess, contact the engagement portion and push the engagement portion until the latch reaches the closed position whereupon the gate can be engaged. 
     Still further in accordance with the present invention, the latch is rotatable about an axis and has a catch portion with a surface generally extending radially from the latch axis which catch surface engages the gate in the closed position. 
     Still further in accordance with the present invention, the quick coupler has a frame comprising two side walls with locking apertures coaxial in the side walls and a locking aperture through the latch which is coaxial with the frame locking apertures when the latch is in the closed position. A pin is provided for insertion through the locking apertures and a pin retention structure is provided on the latch fixing the locking pin in place. 
     Still further in accordance with the invention, a double acting hydraulic cylinder is attached to the gate moving the gate between the open and closed position under operator control. 
     It is the principal object of the present invention to provide a quick coupler which is robust, reliable, easy to use, and inexpensive to manufacture. 
     It is another object of the present invention to provide a quick coupler in which a latch is held in the closed position by reason of a robust piece of steel engaging against a second robust piece of steel. 
     It is yet another object of the present invention to provide a quick coupler in which a control hydraulic cylinder simply moves a gate element into or out of engaged position and does not oppose the force of disengagement. 
     It is still another object of the present invention to provide a quick coupler using a latch and gate engagement and also a locking pin engagement fixing the attach in the closed, engaged position. 
     It is yet another object of the present invention to provide a quick coupler which does not require manual cocking of a mechanism into the open position to make it ready for attachment to an implement. 
     It is still another object of the present invention to provide a quick coupler in which an implement can be engaged, and a gate moved into the closed position from the excavator control station whereupon locking apertures will be aligned with a locking pin easily inserted and fixed in place completing the attachment. 
     It is yet another object of the present invention to provide a quick coupler which is easily maintained in the field, robust, not prone to failure, and having only a minimum of moving parts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing objects, and others, will in part be obvious and in part pointed out more fully hereinafter in conjunction with the written description of the preferred embodiment of the invention illustrated in the accompanying drawings in which: 
     FIG. 1 is a side elevation of a quick coupler in accordance with the present invention, an excavator stick, stick cylinder and bucket; 
     FIG. 2 is a more detailed side elevation of the quick coupler in accordance with the present invention; 
     FIG. 3 is a front elevation of the quick coupler in accordance with the present invention as seen from the excavator side; 
     FIG. 4 shows the quick coupler on FIGS. 1-3 as it begins to engage the mounting pins of an implement; 
     FIG. 5 is a view similar to FIG. 4 with the quick coupler more advanced in the engagement process; 
     FIG. 6 is a view similar to FIG. 5 with the engagement process still more advanced; 
     FIG. 7 is a view similar to FIG. 6 with the quick coupler in the completely engaged position; 
     FIG. 8 is a side elevation of the latch element of the quick coupler of the present invention; 
     FIG. 9 is a front elevation of the latch element seen in FIG. 8; and, 
     FIG. 10 shows the strike plate, gate and hydraulic cylinder of the quick coupler seen in FIGS. 1-9. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now in greater detail to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention and not for the purpose of limiting the invention. FIG. 1 shows a quick coupler  10  in accordance with the present invention fixed to the stick  12  of an excavating machine. An excavating bucket  14  is adjacent to the quick coupler  10 . The quick coupler  10  is shown in more detail in FIGS. 2 and 3. 
     The quick coupler  10  has a frame  16  comprising a two piece left side plate  22 , a two piece right side plate  24 , a central cross brace  26 , a nose plate  28 , and an upper cross brace  30 . As can be seen in FIGS. 2 and 3, the side plates  22 ,  24  are fabricated from outer side plates  22   a ,  24   a  and inner side plates  22   b ,  22   b . The inner side plates  22   b ,  22   b  are welded to the inside surface of the outer side plates  22   a ,  24   a . The spacing between the inner surfaces of the outer side plates  22   a ,  24   a  is appropriate for accepting the stick  12  of an excavator. The spacing between the outer surfaces of the inner side plates  22   b ,  22   b  is approximately the same as the spacing between the inner surfaces of the outer side plates  22   a ,  24   a . This spacing is therefore appropriate for engaging implements, such as bucket  14 , normally engaged by the stick  12 . Shims (not shown) may be used at the welds between the outer side plates and inner side plates to adjust spacing and provide clearance. The left side plate  22  and the right side plate  24  are fabricated from steel plate and have the same general outline. The central cross brace  26 , the nose plate  28  and the upper cross brace  30  are all welded between the two side plates  22 ,  24 . The side plates are thus rigidly interconnected. 
     The left side plate  22  is provided with a hinge bushing  32  and link bushing  34 . The right side plate  24  is provided with a hinge bushing  36  and a link bushing  38 . The two hinge bushings  32 ,  36  are coaxially aligned and the two link bushings  34 ,  38  are also coaxially aligned. A hinge pin  42  passes through the lefthand hinge bushing  32 , lefthand plate  22 , the excavator stick  12 , the right-hand plate  24 , and the right-hand hinge bushing  36 . A bolt  44  and nut  46  are fixed through the right side hinge bushing  36  and the hinge pin  42  fixing it in place and fixing the quick coupler  10  to the stick  12 . In a similar manner, a link pin  48  passes through bushings  34 ,  38  and side plates  22 ,  24  and excavator mounting link  50 . The hinge pin  42  is held in place by a bolt  52  and nut  54  passing through the right side link bushing  38 . A hydraulic cylinder  56  (the bucket cylinder) is fixed to the boom end of the stick  12  and to the excavator mounting link  50 . A pair of brace links  58  are fixed to the stick  12  and to the mounting link  50 . The bucket cylinder  56  can rotate the quick coupler  10  about the axis of the hinge pin  42  and can thus control the positioning of any implement attached to the quick coupler  10 . 
     The nose plate  28  is a thick piece of steel plate interconnecting the bottom of the two inner side plates  22   b ,  22   b  and also providing a rest upon which the quick coupler can stand when not in use. The cross brace  30  rigidly interconnects the upper end of the inner side plates  22   b ,  22   b . The central cross brace  26  rigidly interconnects the central portions of the side plates  22   b ,  22   b , provides a mounting area for other elements to quick coupler and performs other functions described hereinafter. As can be seen in FIG. 1, the bucket  14  is provided with an upper mounting pin  60  and a lower mounting pin  62 . The mounting pins  60 ,  62  are fixed to tabs  64  fixed to the bucket  14  by welding or the like. The pins  60 ,  62  and the tabs  64  are conventionally provided on virtually all implements to be used with an excavator. When a quick coupler is not used, the pins  60 ,  62  are mounted directly to the stick  12  and the link  50  with hinge and link pins. Thus, the bucket  14  and other implements do not need to be modified in any way for use with the quick coupler  10 . 
     The mounting pins  60 ,  62  are generally parallel with one another. In the bucket  14  shown in FIG. 1, the pins  60 ,  62  are generally disposed with the upper pin  60  above the lower pin  62 . A plane through the two pins  60 ,  62  is generally vertical. Other implements for use with this particular excavator and quick coupler will have pins of generally to the same diameter as the pins  60 ,  62  and spaced from one another the same distance as the pins  60 ,  62 . The orientation of the pins may be different in that they may be horizontally disposed with respect to one another in the resting position but in all events, the two pins will define a mounting plane in which the axis of the two pins always resides. 
     As can be seen in FIG. 2, the side plates  22   b ,  22   b  are provided with upwardly opening U-shaped upper recesses  72 . The two side plates  22   b ,  22   b  are also provided with laterally opening U-shaped lower recesses  74 . 
     A latch pivot pin  80  passes through apertures in the side plates  22   a ,  24   a . The latch pivot pin is behind the lower recesses  74 . The latch pivot pin  80  is slightly lower than the center of the lower recess  74 . A latch  82 , that is shown in detail in FIGS. 8 and 9, is rotatable about the latch pivot pin  80 . As can be seen in FIGS. 2 and 3, the latch  82  is supported between the inner side plates  22   b ,  22   b  on the latch pivot pin  80 . The latch comprises a right side latch plate  84 , a left side latch plate  86 , a catch  88 , a brace  90 , and a plunger mount plate  92 . The latch plates  84 ,  86  are identical to one another in outline and rigidly interconnected by the catch  88 , the brace  90  and the plunger mount plate  92 . Coaxial apertures  94  are provided near the center of the latch plates  84 ,  86  and accommodate the latch pivot pin  80 . The preferred latch  82  is welded from several components. The latch  82  could also be cast as a unit. The latch  82  has a forward portion (forward meaning in the direction toward the implement to be attached). The forward portion  96  is generally hook shaped with an upwardly facing recess  98 . The forward portion  96  comprises a closure portion  102  and an engagement portion  104 . The closure portion  102  is the most forward portion of the latch  82 . Its forward edge  106  is flat or curved and the upper portion  108  of the forward edge slants upwardly and backwardly. The engagement portion  104  of the latch is closer to the latch pivot pin  80  than the closure portion  102 . The engagement portion  104  is generally a vertical flat surface on the latch plates  84 ,  86  defining one side of the U-shaped recess  98 . The term vertical is used with reference to the quick coupler  10  sitting on its nose plate  28 . 
     The latch forward portion  96  thus is generally hook-shaped with a nose-like forward surface forming the forward side of an upwardly opening U-shaped recess  98 . This profile is present on both the right side latch plate  84  and the left side latch plate  86 . To the rear of the forward portion  96 , the latch has a locking portion  110 . The locking portion comprises portions of the latch plates  84 ,  86  having locking apertures  112  coaxially disposed through both plates. The plunger mount  92  rigidly interconnects the locking portions  110  of the latch plates  84 ,  86 . 
     The catch  88  is a robust steel plate welded between the two latch plates  84 ,  86 . The catch is shaped like an upside down “T.” It is full width between the two side plates  84 ,  86  and has a tongue portion  114  of reduced width extending above the two latch plates  84 ,  86 , that is, away from the latch pivot pin  80 . Importantly, the catch  88  extends away from the latch pivot pin  80  and in a generally radial direction. The forward wall  116  of the catch tongue and the catch tongue  114  are generally radial with reference to the latch pivot pin  80  and hence the axis of rotation of the latch  82 . 
     FIG. 10 shows the central cross brace  26  in more detail. The central cross brace  26  is welded rigidly between the two frame inner side plates  22   b ,  22   b . It is generally rectangular and has a catch recess  122  in the center of its lower end. A double acting hydraulic cylinder  124  is bolted to the catch plate  26  on its centerline. A piston rod  126  extends from a piston  128  in the cylinder  124  and is fixed to a locking gate  130 . The locking gate  130  comprises a T-shaped gate plate  132  having a long narrow stem  134  generally disposed parallel to the piston rod  126  and an enlarged gate head  136 . The gate head is somewhat wider than the catch recess  122  and has a wear plate  138  bolted to it. Shims (not shown) can be inserted between the gate head  136  and the wear plate  138  as required. As can be seen in FIG. 10, the piston rod  126  moves the locking gate  130  in the direction of the arrow  140 . This allows the cylinder  124  to either close the catch recess  122  with the gate head  136  or open the catch recess  122  by retracting the gate head toward the cylinder  124 . When the piston rod  126  is retracted, the gate  130  is in the open position and the catch recess  122  is open. When the piston rod  126  is extended, the gate  130  is in the closed position and the catch recess  122  is closed. 
     The wear plate  138  has a chamfered forward edge  142 . 
     A spring  144  in the cylinder  124  acts against the piston  128  biasing piston  128  and locking gate  130  into the closed position. If hydraulic pressure to the cylinder  124  is lost, the locking gate is held in the closed position. Retraction is avoided. The cylinder  124  can be replaced with an electrically operated controller such as a solenoid. The solenoid shaft would engage and operate the locking gate  130  as shown in FIG.  10 . The solenoid would be spring biased into the closed position. An electrical signal would cause the solenoid shaft to retract, moving the gate  130  to the open position. The solenoid would be controlled by a switch at the excavator operator position. 
     The interaction of the latch  82 , the gate  130 , and the mounting pins  60 ,  62  is shown in FIGS. 4-7. 
     In FIGS. 4,  5  and  6 , the locking gate  130  is shown in the open position. In FIG. 7, the locking gate  130  is shown in the closed position. 
     FIG. 1 shows the orientation of the quick coupler  10  as it approaches an implement to be connected to the arm  12 . The operator of the excavator has positioned the quick coupler adjacent the bucket  14  and is about to engage the upper mounting pin  60  on the bucket  14  with the upper recesses  72  on the quick coupler  10 . FIG. 4 shows the position just after the upper mounting pin  60  is fully engaged in the upper recess  72 . The operator now extends the bucket cylinder  56  which rotates the quick coupler  10  about the hinge pin  42  and brings the upper portion  108  of the closure portion  102  of the latch  82  into contact with the lower mounting pin  62 . The latch  82  is freely rotatable about the latch pin  80 . As the bucket cylinder  56  is further extended, the quick coupler  10  assumes the position seen in FIG.  5 . The pressure exerted by the lower mounting pin  62  against the upper portion  108  of the latch pushes the latch forward portion  96  downwardly causing the latch to rotate in a clockwise direction. The catch  88  rotates into the catch recess  122  of the central cross brace  26 . The closure portion  102  of the latch  82  is thereby able to slide past the lower mounting pin  62 . 
     As the lower end of the quick coupler  10  continues forward toward the bucket  14 , the engagement portion  104  of the latch  82  engages the lower mounting pin  62 . This causes the latch  82  to rotate in a counterclockwise direction about the latch pivot pin  80 . 
     The bucket cylinder  56  continues its extension until the pin  62  is fully seated in the U-shaped lower recess  74 . The lower pin  62  pushes the engagement portion  104  of the latch  82  into a vertical position, rotating the latch in a counterclockwise direction. The catch  88  is also rotated into a vertical position thereby, out of the space which is now available for the locking gate  130 . The cylinder  124  is actuated by the operator bringing the gate into the closed position with the wear plate  138  bearing against the forward wall  116  of the catch  88 . The sides of the gate head  136  bear against the central cross brace  26 . 
     If the catch  88  is slightly out of position, the chamfered forward edge  142  of the wear plate  138  will engage the catch tongue forward wall  116  and push the catch  88  and latch  82  into the fully closed position. As can be seen in FIG. 7, the lower mounting pin  62  is secure in the lower recess  74 . Because mounting pins  60 ,  62  are a fixed distance apart, the upper mounting pin  60  is also securely retained in the upper recess  72 . The operator can now insert a locking pin  150  through locking apertures  152  in the inner side plates  22   b ,  22   b  and the latch locking apertures  112 . A locking pin retaining screw or spring loaded plunger  154  retained in a threaded hole  156  in the plunger mounting plate  92  is then advanced into a recess in the locking pin  150 . The implement  14  is thereby doubly locked to the quick attach  10  by action of the catch  88  against the gate head  136  and the locking pin  150 . 
     When the locking gate  130  is in the open position, the latch  82  is freely rotatable within its range of motion. It is not spring biased or otherwise biased in a particular position. As shown in FIGS. 4-7, the movement and positioning of the latch  82  is governed simply by gravity and by the influence of the lower mounting pin  62  on shaped surfaces such as the upper portion  108  of the closure portion  102  and the engagement portion  104 . These surfaces are shaped and spaced from the latch pivot pin to provide the movements seen in FIGS. 4-7 without the need for active biasing of the latch  82  in any way. 
     The latch pivot pin  80  is retained in place by means of a retainer  162  welded to the end of the pivot pin  80 . The retainer is provided with a bolt hole through which a bolt  164  is passed and fastened to the right side plate  24  upper frame  16 . 
     A cylinder guard  166  comprising a rectangular piece of steel plate is bolted over the hydraulic cylinder  124  to protect it. 
     Grease fittings, wear plate shims and the like are provided as required. 
     In the preferred embodiment, the upper U-shaped recesses  72  have openings facing upwardly. Such openings could face downwardly and still properly coact with the laterally opening lower recesses. In such an arrangement, the quick coupler  10  will be brought into engagement with the implement  14  by bringing it downwardly so that the upper recesses engage the upper pin  60  from the top. Thereafter, the quick coupler  10  would be rotated about the hinge pin  42  and the operation seen in FIGS. 4-7 would occur just as described. 
     The upper and lower recesses could be interchanged. That is, the lower recess could open downwardly and the upper recess could open laterally and be closed by the latch. However, such an arrangement would probably be more difficult in a conventional excavator because the upwardly opening recess would be controlled by the cylinder  56  making attachment somewhat difficult. 
     The upper recess  72  could be replaced with a lateral recess identical to the lower recess  74 . A second latch would then be required. In such an arrangement, mounting of an implement  14  would be accomplished by moving the quick coupler  10  laterally toward the implement until both pins were properly seated and then locking the gates. 
     The quick coupler  10  is constructed from substantial steel plate elements. In the preferred embodiment, the frame side plates  22 ,  24  and latch side plates  84 ,  86  are constructed from 1¼″ steel plate. The strike plate  26  is constructed from 1″ thick steel plate. The other elements are similarly robust. All of these elements are welded into a very rigid quick coupler  10  suitable for use with heavy construction equipment and the like. 
     While considerable emphasis has been placed herein on the structures of the preferred embodiment and the structural interrelationships between component parts thereof, it will be appreciated that many changes in the embodiment herein illustrated and described can be made without departing from the principles of the invention. Several such changes have been described above. More will occur to those skilled in the art. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely illustrative of the present invention and not as a limitation.