Patent Publication Number: US-8528239-B2

Title: Quick coupling device for connecting a tool to a handling equipment, such as the arm of an excavator

Description:
BACKGROUND OF THE INVENTION 
     The present invention refers in general to equipments the be used for excavation, demolition or earthwork operations, and relates in particular to a quick coupling device for connecting a tool to a handling equipment, such as the articulated arm of an excavator, or similar. 
     Known devices that allow tools, such as buckets, cutters and demolisher hammers, to be quick coupled to the articulated arm of an excavator in different working phases during execution, earthwork or demolition operations, allow the time to substitute the tools to be reduced. In the most common case, these devices comprise a first support member connected to the free end of the articulated arm and a second support member connected to the tool, which support members can be mutually connected by mechanical coupling members that comprise a pair of generally parallel pins interposed between the aforesaid support members. 
     Some known quick coupling devices, such as for example that one described in GB-A-2 330 568, comprise movable hook members associated with the first support member, and therefore with the end of the handling arm, which are rotatably mounted in order to allow the aforesaid pins connected to the second support member to be grasped or released, rotation of the hook members being controlled by a hydraulic or mechanical control system. 
     Although these known devices allow the tools to be connected to an articulated handling arm to be replaced quickly, they have the drawback that they acquire clearances in the use, as a result of the wear the mechanical members of the coupling device are subjected to, because of the severe stresses the tools and the handling arm undergo in the use. These clearances cause the stability of the connection to be degraded in the time, and originate annoying vibrations that can cause a progressive damaging of the tools and of the handling arm up to jeopardize their correct operation. 
     Moreover, these known devices have relevant sizes in the axial direction of the handling arm and are remarkably cumbersome, which reduces their versatility of use and might negatively modify geometry and possibility of movement of the tools. 
     In particular, the invention relates to a quick coupling device for connecting a tool to a handling equipment, such as the arm of an excavator, comprising a first support member adapted to be connected to an end of said arm, and a second support member adapted to be fastened to the tool to be connected to said arm, wherein said support members are mutually engageable as a result of a relative movement along an axis of coupling generally transverse to the end of said arm, each support member comprising two opposed coupling formations having a double inclination so as to converge towards the axis of coupling both along the direction of mutual connection of the support members and with respect to a plane transverse to the axis of coupling, one of the support members including movable holding means which are adapted to engage at least a corresponding seat of the other support member in the mutually coupled configuration of the support members in order to cause mutual locking of the two support members. 
     EP-A-1 353 011 discloses a coupling device of the type defined above, which is adapted to allow a working tool to be removably connected to a working machine. The device comprises a first support member in the form of a trapezoidal plate, connected to the machine, and a second support member, having a seat which shape correspond to said plate, connected to the tool. The side edges of the first support member, which are tapered with respect to the axis of coupling in the second portion and the cross-sectional of which is V shaped, are intended to engage side guide formations the shape of which corresponds to that of a second support member. Owing to the shape of the side edges of the plate and the seat, which allow the first and a second support member to be kept in predetermined mutual positions, the plate of the first support member cannot be pushed against the counter surface of the seat. Moreover, the second support member, at the narrow end of the trapezoidal seat, is provided with an abutment crosspiece that constitutes an end-of-stroke member, and that limitates therefore the introduction of the first member in the respective seat. In this manner, the plate of the first member can be inserted into the seat of the second member only until it interferes with such a crosspiece, which prevents the possibility of recovering clearances between the two support members. Because of the structure of the device of this document, therefore, clearances between the side edges of the first support member and the respective guide formations of the second member may originate, that can not be easily recovered and that, in the use, may cause vibrations to arise. 
     SUMMARY OF THE INVENTION 
     In order to overcome such drawbacks, the subject of the invention is a quick coupling device of the type defined in the appended claims. 
     In particular, in the device according to the invention, the second support member lacks in any end-of-stroke member for stopping the relative movement of the support members along the axis of coupling, and both the opposite coupling formations of the second support member have respective guide surfaces facing a base portion of the second support member in order to define, together with said base portion, respective undercut side seats for the engagement of the opposite coupling formations of the first support member so that, as a result of the relative movement of the support members along the axis of coupling and owing to the mutual engagement of said opposite coupling formations, the first support member wedge into the second support member so that a force of connection is generated, that is applied to the support members and is directed perpendicular to the axis of coupling, which causes the connection between them to be forced proportionally to the force of insertion of the first support member into the second support member. 
     By virtue of this idea of solution, the device of the invention allows the tools to be connected to the handling arm, to be replaced in a simple and safe manner, and at the same time their mutual connection to be made particularly firm and effective in addition to avoid any possibility of accidental uncoupling. Moreover, by virtue of the structure of the quick coupling device of the invention, its size is particularly compact in the axial direction of the handling arm, to full advantage of the versatility of use and of the possibility of movement of the tools connected by it to the arm. 
     According to a preferred feature of the invention, said holding means are resiliently urged so as to snap engage at least a respective seat formed in the second support member. 
     In this manner, the holding means allow a further safety of the coupling to be assured for the quick coupling device. 
     According to another preferred feature of the invention, the holding means allow that possible clearances are automatically recovered, which are originated between the support members in the direction of the axis of coupling. 
     In this manner, the device of the invention turns out to be particularly effective in the use since it is not affected by possible mechanical clearances that could originate in the use between its members as a result of the high stresses the tools and the handling arm are subjected to, which allows arising of vibrations to be considerably reduced. 
     Further characteristics and advantages of the invention will ensue more clearly from the following detailed description, supplied as a non limitative example and referred to the appended drawings that show two exemplifying embodiments of the invention, and in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view of an excavator provided with an arm for handling a tool, 
         FIG. 2  is a schematic perspective view of a quick coupling device according to a first embodiment of the invention, adapted to connect a tool to the handling arm, 
         FIG. 3  is a perspective exploded view of the main elements of the device of  FIG. 2 , 
         FIG. 4  is a perspective view of the elements of  FIG. 3  in their condition before the mutual connection, 
         FIG. 5  is a side elevational view sectioned along line V-V of  FIG. 4 , 
         FIGS. 6 to 9  are top elevational views similar to each other showing as a sequence the coupling steps of the coupling device according to the first embodiment of the invention, 
         FIGS. 10 and 11  are views similar to  FIGS. 6 to 9  showing the uncoupling steps of the coupling device of the first embodiment of the invention, 
         FIG. 12  is a schematic perspective and exploded view of the main components of a second embodiment of the coupling device of the invention, and 
         FIGS. 13 to 15  are side elevational and sectioned views showing as a sequence the coupling steps of the coupling device of the second embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference to  FIG. 1 , a working tool  10 , for example a demolishing hammer, is connected through a quick coupling device indicated  18  in its whole, to the free end  12   a  of an articulated arm  12  of an excavator  14 , in order to allow demolition works to be performed. Of course, the tool  10  to be connected to the arm  12  by the device  18  can be of a any known type, such as a bucket or a cutter, in the case in which it is required to perform earthwork or digging works by the excavator  14 . 
     With reference to  FIGS. 2 to 11 , which show a first embodiment of the invention, in the most common case, two parallel brackets  15  extend from the end  12   a  of the arm  12  according to a fork configuration, in which respective pairs of holes  16  are formed in order to allow insertion of two transverse pins  19  ( FIG. 1 ). The pins  19  engage also holes  21  formed in another pair of parallel brackets  20  extending according to a fork configuration from a first support member  22  of the device  18 . 
     The device  18  comprises also a second support member  24  intended to be fixed to an end face of the tool  10 , for example, in the case of a demolishing hammer, to an end of its elongated body opposite to that one from which a working tip extends. The members  22  and  24  are intended to be mutually engaged as a result of a relative movement, typically a movement of the first member  22  with respect to the second member  24 , along an axis of coupling indicated by A, which extends along a direction generally transverse to the end  12   a  of arm  12 . 
     Usually, the member  22  consists of a flat plate, but it might have an arched shape also. It has a substantially isosceles trapezoidal shape in plan, that is conveniently symmetrical with respect to the axis A. Both the two opposite inclined edges of the member  22  extend according to directions that converge towards the axis A. Each of such inclined edges has a coupling surface  26  inclined with respect to the general plane of the member  22 , in such a manner that the two opposite surfaces  26  converge also with respect to planes transverse to the axis A. 
     The member  24  has an upper seat substantially shaped as an isosceles trapezoid which shape corresponds to that of the member  22 , which seat is limited sideways by a pair of opposite, preferably symmetrical, inclined edges converging towards the axis A. Such edges have respective coupling surfaces  28  inclined with respect to the general plane of the member  24 , so that the opposite surfaces  28  converge also with respect to planes transverse to the axis A. 
     In the most general case, the coupling surfaces  26  and can be rectilinear or arched or curvilinear, correspondingly to each other, so as to constitute a double wedge coupling system which allow a remarkable solidity of coupling to be achieved. 
     The member  24 , which is also conveniently made with the shape of a flat, or possibly arched, plate so as to correspond to the member  22 , may consist of a single piece, or comprise a base plate  25   a  to which a pair of side auxiliary plates  25   b  are fixed on its upper face, each of which forms a respective edge provided with a respective surface  28 . 
     The pairs of surfaces  26  and  28  of the member  22  and of the member  24 , which have a double inclination, constitute mutual engagement formations of the device  18 , adapted to attain a wedging according to two perpendicular directions, which allows an extremely solid and effective locking to be achieved. 
     Holding means are associated with the device  18  in order to firmly hold the elements  22  and  24  in the mutual engagement condition. In particular, the member  22  has a substantially arched cavity  30  formed in its thickness, that preferably opens towards the arm  12 , in which a usually preloaded leaf spring  32  is inserted, in such a manner that the opposite ends  34  of the spring  32 , in the usual condition, project from opposite sides of the member  22  close to an end of its inclined edges  26 . 
     The member  24  has respective seats  36 , close to one of the ends of its inclined edges  28 , intended to receive the ends  34  of the spring  32  in the mutually coupled configuration of the members  22  and  24 , in order to lock them mutually. 
     Preferably, the ends  34  of the spring  32  are tapered in such a manner that, as a result of insertion of the member  22  in the seat of the member  24 , the ends  34  are snap engaged in the seats  36  of the member  24 . 
     Moreover, the seats  36  have an entry portion  36   a  at their side opposite to the edges  28 , which is conveniently inclined with respect to the axis A, so that engagement of the tapered ends  34  of the spring  32  in such slanted entry portions  36   a  causes a thrust to be applied to the member  22  towards the member  24  along the direction of the axis A, in order to allow possible clearances that might be originated in the direction of the axis A between the support members  22  and  24  as a result of the use of the device  18 , to be recovered automatically. 
     Also other types of holding means, for example made by a pair of preloaded spring pins or cam members and resiliently biased towards an extended configuration that project from one or more sides of the member  22  can be used, which are intended to snap engage one or more respective seats  36  of the member  24 . 
     Conveniently, disengaging means for disengaging the ends  34  of the spring  32  from the seats  36  of the member  24 , are associated with the member  22 , which can be operated when it is necessary to separate the tool  10  from the arm  12 . These disengaging means can be remotely controlled, for example by the operator of the excavator  14 , in which case they comprise an actuator (not shown in the figures), particularly hydraulically or electrically controlled, which is associated with the first member  22  and is adapted to control retraction of the ends  34  of the spring  32 , for example by increasing its bending in the seat  30 , in order to extract such ends from the seats  36  of the second member  24 , so that the members  22  and  24  can be separated as a result of their relative movement along the axis A. 
     As an alternative to the solution of remote control, and according to a simpler measure that can be used with quick coupling devices  18  adapted for tools  10  having a lower weight, the disengaging means can be of the mechanical type adapted to be manually driven. According to what shown in the figures as an example, a screw  40  can be associated with the first member  22 , which engages a through threaded axial hole  38  opening in the cavity  30 . By screwing the screw  40  in the hole  38 , its end facing the spring  32  moves until it interferes with the central portion of the spring  32  and pushes it in order to increase its bending so as to cause the ends  34  to be retracted with respect to the sides of the member  22 . 
     As an alternative, other disengaging means of the mechanical type or remotely controlled by different kinds of actuators can be used in order to cause the ends of the spring  32  or of other appendages protruding from the member  22  to be retracted, so as to unlock the member  22  with respect to the member  24 , when such members need to be separated starting from their mutually engaged condition. 
     The operation of the quick coupling device  18  of the first embodiment is schematically shown in  FIGS. 6 to 11 . 
     During the coupling step of the device  18  ( FIGS. 6 to 9 ), the member  22  is aligned with respect to the member  24 , along the direction of the axis A. As a result of the linear approach of the member  22  with respect to the member  24  (arrow B of  FIG. 6 ), the lower face of the member  22  is brought into contact with the upper face of the seat formed in the member  24 , and slides until the inclined edges  26  and  28  are brought into mutual contact. The relative movement of the elements  22  and  24  goes on until the ends  34  of the spring  32  interfere with the front edge of the member  24  ( FIG. 7 ). A further movement of the member  22  along the direction of the axis A (arrows C and D of  FIGS. 7 and 8 ), by virtue of the tapered shape of the ends  34  and of their interference with the front surface of the member  24 , cause the spring  32  to be contracted and its ends  34  to undergo a corresponding retraction until the latter snap engage the seats  36  of the member  24  ( FIG. 9 ). In this configuration, by virtue of the tapered shape of the ends  34  and of the inclination of the entry portion  36   a  of the seats  36 , a resilient force is originated between the ends  34  and the portions  36   a  of the seats  36 , which force tends to compress the member  22  towards the member  24  along the direction of the axis A, so as to allow possible clearances originated between the two members  22  and  24  in the use, to be automatically and resiliently recovered. 
     In order to disengage the quick coupling device  18  when the tool  10  has to be separated from the arm  12  ( FIGS. 10 and 11 ), with reference to the mechanical solution of the disengagement means described above and shown in the figures, the screw  40  is screwed in the hole  38  so that one end of it projects into the cavity  30  in which the spring  32  is arranged, until the end of the screw  40  interferes with the central portion of the spring  42 . By screwing some more the screw  40 , it causes bending of the spring  32  to be increased and, as a consequence, its ends  34  to be retracted until the seats  36  are released, in such a manner that the member  22  can be extracted from the seat of the member  24  by a rectilinear relative movement along the axis A (arrow E of  FIG. 11 ). 
     A second embodiment of the invention will be now described with reference to  FIGS. 12 to 15 , in which elements equal or similar to those of the first embodiment have been indicated by the same numeral references. In particular, the elements already described with reference to the first embodiment will not be described again. 
     In this case, the holding means associated with the quick coupling device of the invention, here indicated  18   a  in its whole, comprise a cavity  36   a  formed in a central zone of the base plate  25   a , which cavity has a surface inclined towards the entry zone of the plate  22  in the seat of the member  24 , so that the cavity  36   a  has a wider section facing the plate  22 . 
     The trapezoidal plate  22 , in its turn, has a shaped central zone  40 , closer to its wider edge perpendicular to the axis A. In the upper portion of the seat  40 , at parts sidewise opposite to the longitudinal axis of coupling A, two semi-cylindrical seats  42  are formed for the engagement of opposite ends  44  of a shaft  46  perpendicular to the axis A. An eccentric member  45  is fixed to the shaft  46 , which projects radially from it towards the wider transverse side of the trapezoidal member  22 . 
     A transverse section of the member  45  has the shape of a substantially circular sector with a center angle of about 50°-60°, limited on its upper and lower part by a pair of almost radial surfaces between which a smooth outer radial surface extends, opposite to the shaft  46 , the distance of which from the shaft  46 , namely its radius with respect to the axis of such a shaft, slightly increases between the lower radial surface and the upper surface of the member  45 . The radially outer surface of the member  45  is intended to cooperate with the inclined surface of the cavity  36   a , the inclination of which promotes sliding on it of such a radially outer surface. 
     The seat  40  is closed on the top by a cover  50  fixed to the member  22  by screws  52  crossing through holes  54  formed in the cover  50 , which are screwed in corresponding threaded holes of the plate  22 , that open in the seat  40 . In particular, the cover  50  has on its lower surface a pair of half-cylindrical seats  49  arranged in positions corresponding to the seats  42  and defining, together with the seats  42 , cylindrical seats for rotatably receiving the ends  44  of the shaft  46 . 
     A return helical spring  56  surrounds one of the ends  44  of the shaft  46  and comprises two projecting end branches one of which rests against a projection  45   a  of the eccentric member  45 , while the other rests against the cover  50 , with the aim of applying a resilient thrust to the eccentric member  45  in order to urge it to the bottom, in a position in which it projects below the plate  22 . 
     Moreover, an almost tangential hole  48  is formed on the upper surface of the member  45 , which can be engaged by the tip of a tool (not shown) in order to allow the member  45  to be drawn into rotation against the resilient action of the spring  56 . 
     In operation of the device  18   a , and with particular reference to  FIGS. 13 to 15 , coupling of the members  22  and  24  requires the member  22  to be aligned in the direction defined by the axis of coupling A of the member  24 . As a result of a movement of the member  22  along the axis A in the direction indicated by arrows E of  FIGS. 13 and 14 , such as already described with reference to the first embodiment, the lower face of the member  22  is brought into contact with the upper face of the plate  25   a  that limits the seat formed in the member  24 , and it slides until the pair of inclined edges  26  and  28  reach mutually facing positions. 
     Going on the relative movement of the members  22  and  24 , the lower radial surface of the eccentric member  45  interferes with the front edge of the member  24  and therefore the member  45  rotates about the axis of the shaft  46  (in the clockwise direction, with reference to the figures), against the resilient action of the return spring  56 , until a position is reached in which its lower surface substantially rests on the plate  25   a  ( FIG. 14 ). 
     As a result of a further sliding of the member  22  with respect to the member  24  in the direction of arrow E, the eccentric member  45  reaches the cavity  36   a  and, when its lower edge reaches the upper edge of the inclined wall of the cavity  36   a , owing to the stress caused by the spring  56 , it snap engages such a cavity ( FIG. 15 ). In this configuration, the inclined edges  26  and  28  reach the mutual contact condition and the opposed coupling formations  26  of the first support member  22  engage the undercut side seats defined between the base portion  25   a  and the opposed coupling formations  28  of the member  24 , in such a manner that the first member  22  wedges into the second member  24 . As a consequence, a coupling force is applied to the support members  22  and  24 , which is directed perpendicular to the axis of coupling A and causes a forced coupling to be accomplished, the entity of which is proportional to the force of insertion of the first support member  22  into the second support member  24 . Moreover, the radially outer surface of the member  45 , by virtue of such an inclination, begins to slide on the inclined surface of the cavity  36   a.    
     Since the radius of the radially outer surface of the member  45  increases from its lower radial surface to its upper radial surface, sliding of the member  45  on the inclined surface of the cavity  36   a , as a result of the thrust of the spring  56  applied on the shaft  46 , and therefore on the member  22 , originates a thrust in the direction of the axis A, which causes a further forward movement of the member  22  with respect to the member  24 . By virtue of the shape of the edges  26  and  28  and of this thrust applied to the member  22 , the member  22  wedges into the member  24  and originates a forced coupling owing to the contact of the member  22  against the plate  25   a . By virtue of this forced coupling, possible clearances existing between the members  22  and  24  in the direction perpendicular to the plate  25   a  are eliminated automatically, since the eccentric member  45 , in the case in which such clearances should exist, penetrates more into the cavity  36   a  and therefore originates a greater thrust on the member  22  in the seat of the member  24 , which wedges more the member  22  into the member  24 . 
     In order to disengage the quick coupling device  18   a , when separation of the tool  10  from the arm  12  is required, the eccentric member is rotated in such a manner that it disengages the cavity  36   a , by means of a tool inserted in the hole  48  of the eccentric member  45 , which is operated so as to overcome the resilient action of the spring  56 , so as to allow the member  22  to be extracted from the seat of the member  24  along the axis A. 
     As an alternative, a remote control device for controlling the position of the eccentric member  45  can be provided, which includes an actuator (not shown in the figures), for example hydraulically or electrically controlled, for controlling the rotation of the member  45  against the resilient thrust action of the spring  56 . 
     In both the embodiments described above, the second support member  24  do not comprise any end-of-stroke member for stopping the movement of the support member  22  with respect to the support member  24  along the axis of coupling A, so that the support member  22  can be inserted to the bottom of the seat of the member  24  until any relative clearance is eliminated, so as to assure always that an optimal forced coupling of the members  22  and  24  is achieved.