Accessory detachable mechanism of construction machine

Abstract: A construction machine typically comprises a mobile chassis having an arm vertically swingably mounted thereon, and a working accessory (118) is detachably retained by the tip end of the arm. The arm has a link arrangement (111,112) with pin holes at upper and lower portions thereof, retaining grooves (113) at upper end thereof. The accessory has pin holes (120,121) at front rear portions thereof. Retaining elements such as rings (131) or pin are fixed to the accessory. The retaining rings or pin are fitted in the retaining grooves to position the accessory so connecting pins (115,116) can be inserted into the pin holes to connect the accessory to the arm.

Description: The present invention relates to a construction machine for use in digging and levelling the ground and particularly to a coupling mechanism for detachably attaching an accessory to an arm of the construction machine. Construction machines such as excavators are employed for earth work or construction work. A conventional excavator has an arrangement in which an accessory like a bucket or breaker is connected to the tip end of the arm. When the arm and the accessory are vertically swung by a hydraulic cylinder, earth and sand are dug out for forming holes or drains. However, the excavator is used not only for digging holes or drains, but may be diverted to other projects which require different accessories. For example, the bucket may be selected to have a size adapted for a specific trenching width, thereby enabling the excavator to work depending on hardness of earth and width of holes or drains. Alternatively, a breaker may be connected to the tip end of the arm or a grip may be employed for carrying out the loading or unloading of objects. A combination of various kinds of these accessories enables the excavator to adapt to various projects, thereby improving the applicability at the construction work site. To change an accessory such as a bucket attached to the tip end of the arm two pins connecting the arm and the bucket are manually removed and the bucket manually detached from the arm. A substitute accessory is manually connected to the arm by inserting connecting pins into the accessory and the arm. The series of operations for attaching the accessory to or detaching the accessory from the excavator arm is carried out through tedious human effort. Several operators are involved in the attaching and detaching operations, which impedes the efficiency at the working site. Furthermore, since it takes time to align and replace pins and accessories, it was impossible to maximise replacement of the accessory at the working site. If one operator alone can attach the accessory to and detach the accessory from the arm, then the other operators required for replacing the accessory can be eliminated. Furthermore, in the connection between the arm and the accessory, if the connection between the arm and the accessory is made by pin connection using pins which are received in pin holes and not by a mere hooking connection, the connection is improved because less deformation of the mechanism will be achieved even if a great operating force is applied to the accessory and the arm. Accordingly, in a first attempt to solve the accessory problem, the inventor proposed an accessory coupling mechanism including a pair of holding pawls which are provided at the tip end of the arm and capable of extending and contracting vertically (EP-A-0 468 771). Alternatively, a pawl may be provided at the upper side of the tip end of the arm and a connecting pin, which can be extended to the right or the left is provided at the lower portion of the pawl. The inventor also proposed a structure in which the arm has a horizontal groove which is open at the tip end and a connecting rod fixed to the accessory is inserted inside the horizontal groove so as to be gripped in the horizontal groove when hooked by a pawl provided at the upper portion of the tip end of the arm. In these related arrangements as disclosed in co-pending EP-A-0 468 771, the arrangement is complex and the pawl is deformed if a great operating force is applied to the accessory. Furthermore, the arm and the accessory are frequently turnably operated and consequently it is preferable that the arm and the accessory are connected by a pin connection. The state of the art will be better understood by reference to US-A-4 643 631, with respect to which claim 1 has been characterised. It is desired to develop a construction machine having a coupling mechanism for detachably attaching an accessory so that; the accessory can be easily connected to the arm and the positioning of the pin holes through which the connecting pins are inserted by pin connection is simplified. The accessory is normally connected to the arm by a link mechanism in which both the accessory and the arm can be swingably connected to each other so that the angle between the accessory and the arm can be varied during the operation of the specific work. Accordingly, if the operating force is applied to the accessory, this force is concentrated on the connecting portion whereby the connecting member is liable to deform if connected by only one connecting pin. Therefore, it is preferable that the accessory is connected to the arm by pin connection at two positions respectively located at front and rear portions of the accessory. According to the present invention there is provided a construction machine having a coupling for detachably attaching an accessory as defined in claim 1. According to the present invention, it is possible to quickly detach and attach accessories to the arm in order to reduce the numbers of operators required and increase the efficiency of the work. Embodiments of a construction machine having a coupling mechanism in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an excavator and the coupling mechanism for connecting a bucket to an arm of the excavator according to a first embodiment; Fig. 2 is an enlarged perspective view showing the arrangement of each component adjacent to the tip end of the arm; Fig. 3 is an enlarged perspective view showing a mechanism adjacent to the tip end of the arm and a mechanism of the bucket; Fig. 4 is a plan view showing the relation between the portion adjacent to the arm and the attached bodies of the bucket; Fig. 5 is a cross-sectional view showing the bucket attached to the tip end of the arm; Fig. 6 is a perspective view showing one positional relation between the arm and the bucket; Fig. 7 is a view showing the tip end of the arm approaching the bucket; Fig. 8 is a view showing the bucket connected to the arm by one connecting pin; Fig. 9 is a view showing the bucket connected to the arm by two connecting pins; Fig. 10 is a perspective view showing the mechanism for connecting a bucket to an arm of an excavator according to a second embodiment of the present invention; Fig. 11 is an enlarged perspective view showing the arrangement of each component adjacent to the tip end of the arm; Fig. 12 is an enlarged perspective view showing a mechanism adjacent to the tip end of the arm and a mechanism of the bucket; Fig. 13 is a plan view showing the relation between the portion adjacent to the arm and the attached bodies of the bucket; Fig. 14 is a cross-sectional view showing the bucket attached to the tip end of the arm; Fig. 15 is a perspective view showing one positional relation between the arm and the bucket; Fig. 16 is a view showing the tip end of the arm approaching the bucket; Fig. 17 is a view showing the bucket connected to the arm by one connecting pin; Fig. 18 is a view showing the bucket connected to the arm by two connecting pins; Fig. 19 is a perspective view showing the mechanism for connecting a bucket to an arm of an excavator according to a third embodiment of the present invention; Fig. 20 is an enlarged perspective view showing the arrangement of each component adjacent to the tip end of the arm; Fig. 21 is an enlarged perspective view showing a mechanism adjacent to the tip end of the arm and a mechanism of the bucket; Fig. 22 is a plan view showing the relation between the portion adjacent to the arm and the component of the bucket; Fig. 23 is a perspective view showing one positional relation between the arm and the bucket; Fig. 24 is a view showing the tip end of the arm approaching the bucket; Fig. 25 is a view showing the bucket connected to the arm by one connecting pin; and Fig. 26 is a view showing the bucket connected to the arm by two connecting pins. First Embodiment (Figs. 1 to 0): An accessory coupling mechanism of a construction machine according to a first embodiment of the present invention will be described with reference to Figs. 1 to 9. In the first embodiment, Fig. 1 is a perspective view of an excavator as a whole in which an accessory coupling mechanism is provided at the tip end of an arm, Fig. 2 is an enlarged view showing the tip end portion of the arm of an excavator, Fig. 3 is a plan view showing the shapes of each component of the arm and the accessory, Fig. 4 is a plan view showing the shape of each component of the arm and the accessory, Fig. 5 is a cross-sectional view of the tip end portion of the arm and Fig. 6 is a perspective view showing the state where the accessory is hooked by the arm. The construction machine comprises a mobile chassis 101 having an engine and the like mounted thereon and an endless track 102 at right and left sides of the lower portion thereof and capable of freely moving front and rear, left and right. The mobile chassis 101 has a boom 103 having a substantially C-shaped configuration and attached to the front portion thereof so as to be vertically swingable. There are provided a pair of hydraulic cylinders 104 connected between the boom 103 at right and left sides of the substantially central portion thereof and the front portion of the mobile chassis 101, whereby the boom 103 can be vertically swung by the operation of the hydraulic cylinders 104. An arm 105 is connected to an upper end of the boom 103 so as to be vertically movable. A hydraulic cylinder 106 is interposed between a central portion of the boom 103 at the rear surface thereof and the rear end of the arm 105, whereby the arm 105 can be vertically swung relative to the boom 103 by the operation of the hydraulic cylinder 106. A bucket cylinder 107 has a rear end pivotally connected to a rear central portion of the arm 105 while rising links 109 are pivotally connected to the right and left sides of the cylinder rod 108 of cylinder 107. Lower ends of the rising links 109 are pivotally connected to a portion adjacent to the tip of the arm 105 at both sides thereof. A pair of connecting links 110 are pivotally connected to the tip end of the cylinder rod 108 in parallel with each other and the arm 105. Operating links 111 are disposed in parallel with each other between the tip ends of the connecting links 110 and the tip end of the arm 105 and they are swingably connected to each other. A pivotal link mechanism is formed by the am 105, the rising links 109, the connecting links 110 and the operating links 111. Swinging links 112 are connected to both sides of the operating links 111 so as to swing forward and backward. Retaining grooves 113 are defined on the upper ends of the swinging links 112 and open substantially in U-shape in the upper directions thereof. Operating links 111 have pin holes 114 and 115 which are pierced rightward and leftward at the lower and upper ends thereof. The position of the pin holes 115 conform to the rotary axial lines between the operating links 111 and the arm 105 and the rotary axial line of the swinging links 112 relative to the operating links 111. Connecting pins 116 and 117 are inserted into these pin holes 114 and 115. A bucket or other accessory 118 as illustrated in Fig. 1 has a pair of flat-shaped attached bodies 119 which are fixed to an outer periphery of the bucket 118 in parallel with each other. The attached bodies 119 have pairs of pin holes 120 and 121 at the respective front and rear portions thereof. An axial line of pin holes 120 is arranged to be parallel with that of pin holes 121. The interval between the axial line of the pair of pin holes 120 and that of the pair of pin holes 121 conforms to the interval between the pin holes 114 and 115 of the operating links 111. Fig. 2 is an enlarged view showing the accessory coupling mechanism which is positioned adjacent to the tip end of the arm 105. A pin 125 is inserted into the tip end of the cylinder rod 108 and pivotally connects links 110 at the right and left sides of the cylinder rod 108. The rising links 109 are pivotally connected by the pin 125 to the right and left sides of the connecting links 110. The rising links 109 extend downward and have lower ends which are pivotally connected to the portion adjacent to the tip end of the arm 105 by pin 126. The operating links 111 are disposed at right and left sides of the tip end of the arm 105 and extend upward. The upper ends of the operating links 111 are pivotally connected to the tip ends of the connecting links 110 while a collar 127 is interposed between the tip ends of the pair of connecting links 110. Pin holes 114 pierce the connecting links 110 and the collar 127. The swinging links 112 are pivotally connected coaxially to the lower end of the operating links 111 at the right and left sides thereof. Pin holes 115 pierce the swinging links 112, the operating links 111 and the arm 105. Accordingly, the operating links 111 and the swinging links 112 are coaxially connected to each other so as to be swingable about the pin hole 115. Stoppers 128 protrude from the rear central portion of the swinging links 112 (right side in Fig. 2) and extend in the direction of the center of the arm 105. The stoppers 128 are bent inwardly in an L-shape at the tip ends thereof for forming stopping portions 129. The stopping portions 129 can contact the central side surfaces of the operating links 111 and restrict the swinging motion of the swinging links 112, namely, restrain the swinging links 112 not to incline forward over a predetermined angle. The swinging links 112 are recessed at the upper ends thereof so as to form U-shaped retaining grooves 113. The interval between the retaining grooves 113 and the axial line of the pin holes 115 conforms to an interval between the axial lines of the pin holes 114 and 115. Fig. 3 is an enlarged view showing the relation between the attached bodies 119 fixed to the bucket 118, the operating links 111 and the swinging links 112. The pair of flat-shaped attached bodies 119 are fixed to a rear surface of the bucket 118 in a given interval. An internal interval of the attached bodies 119 is set to be A. Retaining rings 131 are fixed to the inner surfaces of the attached bodies 119 in the position coaxial with the pair of pin holes 120. The retaining rings 131 have inner diameters which are the same as the diameters of the pin holes 120 and outer diameters which are set to be C. The pin holes 120 have inner diameters through which the connecting pin 116 is inserted. An interval of the right and left operating links 111, which are connected to the tip end of the arm 105, is set to be B while an interval between the right and left swinging links 112 is set to be dimension A. The retaining grooves 113, defined in the swinging links 112, have inner diameters which are set to be dimension C and the same as the outer diameters of the retaining ring 131. Fig. 4 is a plan view showing the relation between the dimensions A, B and C between the components as illustrated in Fig. 3. As evident from this figure, the entire swinging links 112 can be inserted into the space between the attached bodies 119 while the retaining rings 131 can be inserted into the retaining grooves 113 defined in the swinging links 112. The configurations of the operating links 111 are set in the manner that they can slide between the retaining rings 131. Fig. 5 is a cross-sectional view showing the portion adjacent to the tip end of the arm 105 and showing the state where the connecting pin 117 is inserted into the pin holes 115 and 121 and the bucket 118 is connected to the tip end of the arm 105. A shaft supporter 135 is fixed to the tip end of the arm 105. The shaft supporter 135 is pierced inside thereof to form an opening hole. The operating links 111 are brought into contact with both sides of shaft supporter 135 at the lower surfaces thereof. A cylindrical bearing 136 is fixed to the lower surface of one of the swinging links 112. The bearing 136 is inserted into the opening of the shaft supporter 135 and has a tip end which protrudes through the operating links 111 and is exposed to other side of the arm 105. The other swinging link 112 is brought into contact with the tip end of the bearing 136 at the lower surfaces thereof while the bearing 136 and the swinging links 112 are connected to each other by screws 137. Both swinging links 112 can be turned forward and backward by the bearing 136 about the shaft supporter 135 and the operating links 111 can be freely turned along the outer periphery of the bearing 136. That is, the operating links 111 and the swinging links 112 can be turned on the coaxial lines thereof at the tip end of the arm 105. The pierced opening hole in the center of the bearing 136 corresponds to the pin holes 115. The inner walls of the attached bodies 119 contact both sides of the swinging links 112 and the connecting pin 117 is inserted into the pin holes 121 and 115 whereby the attached bodies 119 and the arm 105 are connected to each other. A washer 139 is inserted into the tip end of the connecting pin 117 which is inserted into the pin holes 121 and 115 while a split pin 138 is inserted into the tip end of the connecting pin 117 perpendicular to the lengthwise of the connecting pin 117. Procedures for mounting the bucket 118 on the tip end of the arm 105 are illustrated in Figs. 6, 7, 8 and 9. As illustrated in Fig. 7, the bucket 118 is placed on the ground and the operator of the excavator sits on the operator's seat of the chassis 101 and operates the boom 103 and the arm 105 so that the operator alone can mount the bucket 118 on the arm 105. Fig. 7 is a view showing the state where the accessory for construction work (the bucket 118 is this case) is not attached to the tip end of the arm 105 and the operation to mount the bucket 118 on the tip end of the arm 105 starts. Before starting the mounting operation, the bucket cylinder 107 is operated to extend the cylinder rod 108 at its maximum so that the operating links 111 are inclined as far as possible to the front portion thereof. In this state, the swinging links 112 turns about the shaft supporter 135 by its own weight so that the swinging links 112 are inclined at the front side of the operating links 111. At this time, the stopping portions 129 defined on the swinging links 112 contact the side surfaces of the operating links 111 to thereby restrain the operating links 111 from opening to the extent exceeding a prescribed angle. As a result, both the operating links 111 and the swinging links 112 open like a fan so that the retaining grooves 113 defined on the upper ends of the swinging links 112 are directed forward as illustrated in Fig. 7. At this state, when the hydraulic cylinders 104 and 106 are cooperatively operated, both the boom 103 and the arm 105 are vertically swung to thereby permit the tip end of the arm 105 to approach the attached bodies 119 of the bucket 118. Accordingly, the pair of swinging links 112 can be inserted into the space of the attached bodies 119 as illustrated in Fig. 7. As illustrated in Figs. 3 and 4, the interval between the inner walls of the attached bodies 119 is set to be A and the interval between the outer surfaces of the swinging links 112 is also set to be A so that the swinging links 112 can be inserted into the space of the attached bodies 119 (refer to Fig. 6). As the boom 103 and the arm 105 are further swung vertically, the retaining rings 131 are permitted to contact the retaining grooves 113 so that the retaining rings 131 are inserted into the retaining grooves 113. The inner diameters of the retaining grooves are set to be C and the outer diameters of the retaining rings 131 are set to be C. Thereafter, both the hydraulic cylinders 104 and 106 are cooperated to thereby lower the arm 105 so that the retaining rings 131 are inserted into the innermost portions of the retaining grooves 113. Further lowering operation of the arm 105 permits the swinging links 112 to turn relative to the operating links 111 so that the operating links 111 are inserted into the space of the attached bodies 119. Consequently, the pin holes 114 of the operating links 111 are positioned at the position where the pins 120 of the retaining rings 131 are located whereby the axial line of the pin holes 120 of the retaining rings 131 conform to the axial line of the pin holes 114 of the operating links 111. At this state, the connecting pin 116 is inserted into the pin holes 120 from one of the side surfaces of the attached bodies 119 so that the connecting pin 116 is inserted into the pin holes 120 and 114. Accordingly, the connecting links 110, operating links 111 and the attached bodies 119 are connected to the attached bodies 119 by the connecting pin 116. Fig. 8 is a view showing the state where the bucket 118 is connected to the connecting point between the connecting links 110 and the operating links 111 by inserting the connecting pin into the connecting point. After the pin holes 114 and 120 are connected by the connecting pin 116, the hydraulic cylinders 104 and 106 are operated, as illustrated in Fig. 9, thereby slightly raising both the boom 103 and arm 105 and slightly pulling up the bucket 118 from the ground. Thereafter, the bucket cylinder 107 is operated to contract the cylinder rod 108 so that the rising links 109 are turned about the pin 126. As a result, the connecting links 110 are interlocked with the rising links 109 so as to pull the operating links 111 which turn about the bearing 136. The bucket 118 is pulled upward as the operating links 111 are turned whereby the bucket 118 is turned counterclockwise by its own weight relative to the operating links 111 as illustrated in Fig. 9. When the bucket 118 approaches the operating links 111, the pin holes 115 approach the pin holes 121 so that the axial line of the pin holes 115 conforms to that of the pin holes 121. Thereafter, the connecting pin 117 is inserted into the pin holes 115 and 121 so that the bucket 118 is connected to the tip end of the arm 105 by the connecting pin 117. With a series of procedures as set forth above, the bucket 118 can be mounted on the tip end of the arm 105. When the bucket 118 is disconnected from the tip end of the arm 105, the connecting pins 117 and 116 are in turn pulled out from the pin holes in the order of the procedures as illustrated in Fig. 9, Fig. 8 and Fig. 7. With the arrangement of the first embodiment, it is possible to position the two pin holes defined on the tip end of the arm to the two pin holes defined on the accessory with ease. In addition, it is possible to connect the arm to the accessory by the two connecting pins although the structure thereof is very simple. Both the arm and the accessory can be securely connected to each other by the pins and can be turned smoothly. Accordingly, there is no likelihood of deformation of the components even if the strong external force is applied to the accessory. Second Embodiment (Figs. 10 to 18): An accessory detachable mechanism of a construction machine according to a second embodiment will be described with reference to Figs. 10 to 18. The construction machine according to the second embodiment is the same as that of the first embodiment, hence the explanation thereof is omitted. Described hereinafter is the coupling mechanism and the accessory. A pair of connecting links 210 are pivotally connected to the tip end of the cylinder rod 208 in parallel with each other and directed forward of the arm 205. A pair of retaining links 211 are disposed between the tip ends of the connecting links 210 and the tip end of the arm 205 and they are swingably connected to each other. A link mechanism is formed by the arm 205, the rising links 209, the connecting links 210 and the retaining links 211. In the connection between the tip ends of the connecting links 210 and the retaining links 211, the tip ends of the connecting links 210 are pivotally connected to the substantially central portions of the retaining links 211 by a pin 227 and the upper half portions of the retaining links 211 are directed forward the excavator. Substantially U-shaped grooves 212 are defined at the upper ends of the retaining links 211 in the longitudinal direction thereof. Flat shaped bearing plates 213 are fixed to the inner portions of the retaining links 211 at the innermost position of the retaining grooves 212 by welding or other conventional means of attachment. The bearing plates 213 have pin holes 228 opened therein. Pin holes 214 are pierced in the central axis about which the arm 205 and the retaining links 211 are turned. A connecting pin 215 can be inserted into or removed from the pin holes 214 while connecting pin 216 can be inserted into or removed from the pin holes 228 of the bearing plates 213. A bucket or other accessory 218 as illustrated in Fig. 11 has a pair of flat-shaped attached bodies 219 which are fixed to an outer periphery of the bucket 218 and parallel with each other. The attached bodies have a pair of pin holes 220 and another pair of pin holes 221 at the front and rear portions thereof. An axial line of the pair of pin holes 220 is arranged to be parallel with that of another pair of pin holes 221. An interval between the axial line of the pair of the pin holes 220 and that of the pair of pin holes 221 conforms to an interval between the axial line of the pin holes 228 of the bearing plates 213 and that of the pin holes 214. Fig. 11 is an enlarged view showing the accessory detachable mechanism which is positioned adjacent to the tip end of the arm 205. A pin 225 is inserted into the tip end of the cylinder rod 208 and the connecting links 210 are pivotally connected by pin 225 at the right and left sides of the cylinder rod 208. The upper ends of the rising links 209 are pivotally connected by pin 225 at the right and left sides of the connecting links 210. The rising links 209 extend downward and have lower ends which are pivotally connected to the portion adjacent to the tip end of the arm 205 by a pin 226. The lower ends of the retaining links 211 are positioned at the tip end of the arm 205 at right and left sides of the arm 205 while the retaining links 211 extend substantially upward. The middle portions of the retaining links 211 and the tip ends of the connecting links 210 are pivotally connected by the pin 227. The substantially U-shaped retaining grooves 212 are defined on the upper ends of the retaining links 211 and extend downward in the longitudinal directions thereof. The bearing plates 213 are fixed to the inner portions of the retaining links 211 at the positions corresponding to the retaining grooves 212 and have the pin holes 228 opened therein. The axial line of the pin holes 228 conform to an axial core of the semicircular arc positioned at the innermost end of the retaining groove 212. Fig. 12 is an enlarged perspective view showing the relation between the attached bodies 219 fixed to the bucket 218 and the retaining links 211. The pair of flat-shaped attached bodies 219 are fixed to a rear surface of the bucket 218. The internal interval of the attached bodies 219 is set to be dimension A. Retaining rings 231 are fixed to the inner surfaces of the attached bodies 219 at the position coaxial with the pair of pin holes 220 and have inner diameters which are the same as the diameters of the pin holes 220 and outer diameters which are set to be dimension C. The inner interval between the confronted two retaining grooves 231 is set to be dimension B. The interval of the right and left retaining links 211, which are connected to the tip end of the arm 205, is set to be A while an inner interval between the confronted retaining links 211 is set to be B. The retaining grooves 212, defined on the retaining links 211, have groove width which is set to be C. Furthermore, the interval between the axial lines of the pin holes 214 and 228 of the retaining links 211 conform to the interval between the axial lines of the pin holes 220 and 221 of the attached bodies 219. Fig. 13 is a plan view showing in part the relation between the dimensions or intervals A and B. As evident from this figure, the outer sides of the retaining links 211 can be inserted into the space between inner walls of the attached bodies 219 while the retaining rings 231 can be inserted into the retaining grooves 212 defined on the tip ends of the retaining links 211. The dimension or interval D between the axial lines of the pin holes 214 and 220 is set to be equal to the interval D between the axial lines of the pin holes 220 and 221. Fig. 14 is a cross-sectional view showing the portion adjacent to the tip end of the arm 205 where the connecting pin 216 is inserted into the pin holes 214 and 221 and the bucket 218 is connected to the tip end of the arm 205. A shaft supporter 235 is fixed to the inside of the tip end of the arm 205. The shaft supporter 235 is of a pipe shape having two flange-shaped ends. A cylindrical bearing 236 is fixed to the side surface of one of the retaining links 211. The bearing 236 is slidably inserted into the opening of the shaft supporter 235 and has a tip end which is brought into contact with the side surface of another retaining link 211. The bearing 236 and retaining link 211 are fixedly connected to each other by screws 237. Therefore, the bearing 236 can turn freely relative to the fixed shaft supporter 235 and the retaining links 211 positioned at both sides of the shaft supporter 235 can swing freely relative to the arm 205. A hole pierced inside the bearing 236 corresponds to the pin holes 214. The retaining links 211 are inserted into the space in the attached bodies 219 at both sides thereof and then the connecting pin 216 is inserted into the pin holes 221 and 214 so that the attached bodies 219 are connected to the arm 205. A split pin 238 is inserted into the tip end of the connecting pin 216 which is inserted into the pin holes 221 and 214 to thereby prevent the connecting pin 216 from dropping out of the attached bodies 219. Procedures for mounting the bucket 218 on the tip end of the arm 205 are illustrated in Figs. 15, 16, 17 and 18. In the procedures, as illustrated in Fig. 16, the bucket 218 is at first placed on the ground and the operator of the excavator sits on the operator's seat of the chassis 201 and operates the boom 203 and the arm 205 so that the operator alone can mount the bucket 218 on the arm 205. Fig. 16 is a view showing the state where the accessory for construction work (the bucket 218 in this case) is not attached to the tip end of the arm 205 and the operation to mount the bucket 218 on the tip end of the arm 205 starts. Before starting the mounting operation, the bucket cylinder 207 is operated to extend the cylinder rod 208 at its maximum so that the retaining links 211 are inclined forward as far as possible to the front portion thereof. In this state, the retaining grooves 212 confront the bucket 218. At this state, when the hydraulic cylinders 204 and 206 are cooperatively operated, both the boom 203 and the arm 205 are vertically swung to thereby permit the tip end of the arm 205 to approach the attached bodies 219 of the bucket 218. Accordingly, the pair of retaining links 211 can be inserted into the space on the attached bodies 219 as illustrated in Fig. 16. As illustrated in Figs. 12 and 13, the interval between the inner walls of the attached bodies 219 is set to be A and the interval between the outer surfaces of the retaining links 211 is also set to be A so that the retaining links 211 can be inserted into the space on the attached bodies 219 (refer to Fig. 15). As the boom 203 and the arm 205 are further swung, the retaining rings 231 are permitted to conform to the retaining grooves 212 and retaining rings 231 are inserted into the retaining grooves 212 since the inner diameters of the bearing plates 213 are set to be C and the outer diameters of the retaining rings 231 are set to be C. In such a manner, the bucket 218 is hooked by the tip end of the arm 205 through the retaining grooves 231 and the bearing plates 213. In this state, if the boom 203 and the arm 205 are operated to permit the retaining rings 231 to be brought into contact with the innermost portions of the bearing plates 213, the axial line of the pin holes 220 conform to that of the pin holes 228. This is because the axial core of the semicircular arc of the bearing plates 213 conform to the axial core of the retaining grooves 231. If the axial core of the pin holes 220 conform to that of the pin holes 228, the connecting pin 215 can be inserted into the pin holes 220 from one side surface of one of the attached bodies 219. Accordingly, the connecting links 210 and the retaining links 211 are connected to the attached bodies 219 by the connecting pin 215. Fig. 17 is a view showing the state where the boom 203 and the arm 205 are slightly swung upward to thereby lift the bucket 218 after the connecting pin 215 is inserted to thereby connect the retaining links 211 to the attached bodies 219. After the bucket 218 is lifted by inserting the connecting pin into the pin holes 220 and 228, the bucket cylinder 207 is operated, as illustrated in Fig. 18, to contract the cylinder rod 208 thereof so that the rising links 209 are turned about the pin 226, and then the connecting links 210 pull the operating links 211 so that the retaining links 211 are turned about the shaft supporter 235. The bucket 218 is pulled upward as the retaining links 211 are turned. The bucket 218 is turned counterclockwise by its own weight relative to the operating links 211, as illustrated in Fig. 18, and the attached bodies 219 approach the tip end of the arm 205. When the attached bodies 219 and the arm 205 approach each other, both the pin holes 214 and 221 approach each other so that both the axial lines of the pin holes 214 and 221 conform to each other. Since the interval between the axial lines of the pin holes 214 and 228 to the interval between those of the pin holes 220 and 221, if both the pin holes 220 and 228 are connected by the connecting pin 215, the axial lines of the pin holes 214 and 221 will conform to each other. Thereafter, the connecting pin 216 is inserted into the pin holes 214 and 221 from the side surface of one of the attached bodies 219 so that the bucket 218 is connected to the tip end of the am 205 by the connecting pin 216. With a series of procedures set forth above according to the second embodiment, the bucket 218 can be mounted on the tip end of the arm 205. When the bucket 218 is disconnected from the tip end of the arm 205, the connecting pins 215 and 216 are in turn pulled out from the pin holes in the order of the procedures as illustrated in Fig. 18, Fig. 17 and Fig. 16. Third Embodiment (Figs. 19 to 26): An accessory coupling mechanism of a construction machine according to a third embodiment will be described with reference to Figs. 19 to 26. The construction machine according to the third embodiment is the same as that of the second embodiment, hence the numerals common to those of the second embodiment are denoted by the same numerals and the explanation thereof is omitted. More specifically, only the accessory detachable mechanism provided at the tip end of the arm 205 is modified. In Fig. 19, connecting links 240 are connected to the tip end of the cylinder rod 208 in parallel with each other while a pair of retaining links 241 are pivotally connected to the tip end of the arm 205. The connecting links 240 and the retaining links 241 are pivotally connected to one another at the tip ends thereof. Accordingly, the arm 205, the rising links 209, the connecting links 240 and the retaining links 241 form a substantially parallelogram link mechanism. Substantially U-shaped retaining grooves 242 are formed at the upper ends of the retaining links 241 and open upward. A pipe-shaped sliding body 243 has both ends which are large in the diameters thereof and are positioned adjacent to the U-shaped retaining groove 242. The sliding body 243 has a pin hole 244 which is open in the central portion thereof in which the axial core of the pin hole 244 conforms to the axial cores of the innermost semicircular arcs of the retaining grooves 242. The sliding body 243 is inserted into holes provided at the tip end of the connecting links 240 at the periphery thereof whereby the connecting links 240 can be slidably connected to the retaining links 241 by the sliding body 243. The pin holes 214 are pierced in the central axis between the tip end of the arm 205 and the retaining links 241 in which the retaining links 241 turn about the central axis. The connecting pin 216 is inserted into the pin holes 214 while the connecting pin 215 is inserted into the pin hole 244 defined in the sliding body 243. Fig. 20 is an enlarged view showing an arrangement adjacent to the tip end of the arm 205 according to this embodiment. The U-shaped retaining grooves 242 are defined at the upper ends of the retaining links 241 and the sliding body 243 is fixed to the upper ends of the retaining links 241 by welding or similar means of conventional attachment. The sliding body 243 has two flange-shaped sides and the flange-shaped sides are respectively brought into contact with and fixed to the inner surfaces of the retaining links 241. The pin hole 244 is defined at the center of the sliding body 243 which is pierced to leftward and rightward in which the axial line of the pin hole 244 conforms to the axial line of the curved surfaces of the innermost semicircular arcs of the retaining groove 242. Fig. 21 is an enlarged perspective view showing the relation of the lengths of the attached bodies 219 fixed to the bucket 218, the retaining links 241, the retaining grooves 242 and each part of the retaining links 241. An inner interval between the attached bodies 219 fixed to the bucket 218 is set to be E while an inner interval between the retaining rings 231 fixed to the inner walls of the attached bodies 219 is set to be F and the outer diameters of the retaining rings 231 are set to be G. The interval between the retaining links 241, which are connected to the tip end of the arm 205, are set to be E while the interval between the inner walls of the retaining links 241 are set to be F and the widths of the retaining grooves 242, which are defined at the upper ends of the retaining links 241, are set to be G. Fig. 22 is a plan view showing the relation between the intervals or dimensions E, F and G of the components as illustrated in Fig. 21. Evident from this figure, the retaining links 241 can be inserted into the space of the attached bodies 219 while the retaining rings 231 can be inserted into the retaining grooves 242. The interval between the axes of the pin hole 214 and the pin hole 244 is set to be H while the interval between the axes of the pin holes 220 and the pin holes 221 is set to be H. Accordingly, when the retaining rings 231 are retained by the innermost portions of the retaining grooves 242, the axial line of the pin holes 220 conforms to that of the pin holes 244 and at the same time the axial line of the pin holes 221 conforms to that of the pin holes 214. The procedure to attach the bucket 218 to the tip end of the arm 205 is explained with reference to Figs. 23, 24, 25 and 26. This procedure flows in the first step where the bucket 218 is placed on the ground and detached from the arm 205 as illustrated in Fig. 15 and in the last step where the bucket 218 is connected to the arm 205 as illustrated in Fig. 26. In the state as illustrated in Fig. 24, the bucket cylinder 207 is first operated to extend the cylinder rod 208 at its maximum while the retaining links 241 are inclined forward as much as possible. Thereafter, two retaining links 241 are directed toward the attached bodies 219 causing the tip end of the retaining links 241 to be directed toward the retaining rings 231. The retaining rings 231 are fitted into the U-shaped retaining grooves 242 and are pushed into the innermost portions of the retaining grooves 242 by swinging the boom 203 and the arm 205. Consequently, the axial lines of the innermost semicircular arcs of the retaining grooves 242 conform to the axial line of the pin holes 220 so that the connecting pin 215 can be inserted from one side surface of one of the attached bodies 219 into the pin hole 244, whereby the retaining rings 241 and the bucket 218 can be connected by the pin 215. As illustrated in Fig. 25, the boom 203 and the arm 205 are operated to swing upward and thereby lifting up the bucket 218 from the ground. The lifted bucket 218 is shown in Fig. 25. At this state, the bucket 218 is hooked by the retaining links 241 by the connecting pin 215, hence the bucket 218 hangs down by its own weight. At the state illustrated in Fig. 25, the bucket cylinder 207 is operated to contract the cylinder rod 208 so that the retaining links 241 turn clockwise. At the same time, the attached bodies 219 are pulled up, and the bucket 218 is directed downward about the connecting pin 215 due to its own gravity so that the bucket 218 is drawn relative to the tip end of the arm 205. As a result, the pin holes 221 defined in the attached bodies 219 approach the pin holes 214 of the arm 205 and cause the pin holes 214 to conform to the pin holes 221 as illustrated in Fig. 26. As explained with reference to Fig. 22, the interval H between the axial lines of the pin holes 220 and 221 is the same as those of the interval H between the axial lines of the pin holes 214 and 244, when the cylinder rod 208 is contracted, and the bucket 218 and the arm 205 relatively approach each other. As a result, the pin holes 221 approach the pin holes 214 and cause the axial core of the pin holes 214 to conform to that of the pin holes 221. At this state, the connecting pin 216 is inserted into the holes from one side surface of the attached bodies 219 so that the arm 205 and the attached bodies 219 are connected by the pin 216. In this way, the bucket 218 can be attached to the tip end of the arm in the procedures as illustrated in the order of Figs. 24, 25 and 26. In the second embodiment, since the connecting links 240 are connected to the portion adjacent to the tip end of the arm 205, the point where the bucket 218 and the connecting links 240 operate conforms to the axial line of the pin holes 215 so that the stress from the bucket cylinder 207 can be transmitted directly to the bucket 218. With the arrangements of the second and third embodiments of the present invention, it is possible to position the two pin holes defined on the tip end of the arm to the two pin holes defined on the accessory with ease and possible to connect the arm to the accessory by the two connecting pins, although the structure thereof is very simple. Both the arm and the accessory can be connected strongly to each other by the pins and can be turned smoothly. Accordingly, deformation of the components is not likely even if a strong external force is applied to the accessory. Furthermore, the structure of the mechanism is very simplified compared with the conventional mechanism and the number of parts is reduced.

Claims: A construction machine having a coupling for detachably attaching an accessory comprising; a mobile chassis (101; 201) and an articulated arm assembly swingably mounted on the chassis to deploy the accessory (118; 218) for use, the coupling mechanism including a pair of retaining links (112; 211; 241) each having a first end mounted via a pivot on the end of the arm assembly, the retaining links (112; 211; 241) being connected to a linkage to be swung around the pivot by the action of an hydraulic ram (107; 207) U-shaped retaining grooves (113; 213; 242) defined at the upper ends of each retaining link, a projecting part on the body of the accessory (119; 219) whereby the "U" shaped grooves (113; 213) can engage the projecting part (131; 231) to guide co-operable pin holes (114, 115, 120, 121; 214, 215, 220, 221) provided in the linkage and the accessory into alignment to receive a locking pin (116, 117; 216, 215) to mount the accessory on the end of the arm assembly, the accessory (118; 218) having pin holes (120, 121; 220, 221) axially aligned and laterally spaced, there being pairs of pin holes (120, 121; 220, 221) in the accessory and, and characterised in that; the projecting part is provided by retaining rings (131, 231) fixed to inner sides of one pair of the pin holes (120, 121; 220, 221) in the accessory to be received into the U-shaped retaining grooves (113; 213; 242) in the retaining links. A machine according to claim 1 wherein the distance between the axis of each retaining groove (113; 213; 242) and the pin hole (115; 214) in each retaining link (112; 211; 241) is the same as the distance between the axis of the co-operable pairs of pin holes (120, 121; 220, 221) in the accessory. A machine according to one of claims 1 or 2 wherein the arm assembly comprises a boom (103; 203) swingably mounted on the chassis (101; 201) adjacent one end, an elongate arm (105; 205) pivotally connected to the boom (103; 203) and spaced from the one end; there being two body parts of the accessory (118; 218) provided by planar, spaced, parallel, first and second attached bodies (119; 219); the linkage including, rising link means (109; 209) connected at one end to a front end of a cylinder (107; 207) and at the opposite end to the end of the arm (105; 205) connecting link means (110; 210) pivotally connected at the rear end to the cylinder (107; 207) and at the front end to a top end of a pin hole link (111; 211; 241), the pin hole link (111; 211; 241) being pivotally connected at the lower end to the end of the arm (105; 205). A machine according to claim 2 or claim 3 wherein the retaining link (112) is mounted to be pivotal independently of the linkage (109, 110, 114) to provide for connection of the accessory (118) to the end of the arm. A machine according to claim 4 wherein pin hole links (111) are provided as part of the linkage on the end of the arm assembly, the pin hole links (111) having coaxial pin holes at upper and lower portions into which connecting pins (115, 116) can be received, an end of each retaining link (112) being pivotally mounted one each respectively to the right and left sides of each pin hole link (111) so that the retaining grooves (113) can be directed upwards, the distance between upper and lower pairs of pin holes (114,115) in the pin hole links (111) being the same as the distance between the pin holes (120, 121) in the accessory. A machine according to claim 5 wherein the retaining links (112) are each provided with a stopper (128) which protrudes from the rear central portion of each retaining link (112) towards the arm assembly, each stopper being bent inwardly in an L-shape to provide a stopping portion (129) engageable with an arm facing edge of each adjacent pin hole link (111) to restrict the angle through which each retaining link (112) can pivot with respect to each pin hole link (112). A machine according to one of claims 1, 2 or 3 wherein flat shaped bearing plates (213) are fixed to the inner portions of the retaining links (211) at the innermost position of the retaining grooves (212) and have pin holes (228) therein. A machine according to one of claims 1, 2 or 3 wherein one of the pin holes (244) is provided in a sliding body (243) fixed to the upper ends of the retaining links (241).

Inventors: KISHI MITSUHIRO C O JAPANIC CO, KISHI, MITSUHIRO, C/O JAPANIC CORPORATION
Applicants: JAPANIC CORP, JAPANIC CORPORATION
Application year: 1992
Main classification: E02F3
IPC codes: E02F3