JP2011074745A - Construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep constant the opening angle between a first boom section and a second boom section. <P>SOLUTION: A first pin mounting hole 26 and a second pin mounting hole 27 are provided to the front end of the first boom section 12, and a boom connection pin 16 is selectively fitted to either of the first and second pin mounting holes 26, 27. Thereby, when a load acts on a positioning cylinder 23 in the retracting direction during the disassembling operation, the holding force of the positioning cylinder 23 can be secured by the product of the extension/retraction force of the positioning cylinder 23 in the extending direction and the shortest distance L1 between the center of the first pin mounting hole 26 and the axis O1-O1 of the positioning cylinder. When a load acts on the positioning cylinder 23 in the extending direction during the excavating operation, the holding force of the positioning cylinder 23 can be largely secured by the product of the extension/retraction force of the positioning cylinder 23 in the retracting direction and the shortest distance L2 between the center of the second pin mounting hole 27 and the axis O1-O1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a construction machine such as a hydraulic excavator, and more particularly to a construction machine including a two-piece boom specification working device having a first boom and a second boom.

  In general, a hydraulic excavator as a typical example of a construction machine is a self-propelled lower traveling body, an upper revolving body that is turnably mounted on the lower traveling body, and an uplifting motion on the front side of the upper revolving body. It is roughly constituted by a working device that can be provided. The working device normally has a boom whose base end side is rotatably connected to the upper swing body, an arm rotatably connected to the distal end side of the boom, and is rotatable to the distal end side of the arm And a boom cylinder, an arm cylinder, and a work tool cylinder for operating these booms, arms, and work tools.

  In addition, a two-piece boom type working device is known in which the boom is divided into a first boom and a second boom in order to expand the movable range of the working device. The two-piece boom has a first boom whose base end side is rotatably connected to the upper swing body, and a second boom whose base end side is rotatably connected to the distal end side of the first boom via a boom connecting pin. A boom and a positioning cylinder that is provided between the first boom and the second boom and rotates the second boom with respect to the first boom around a boom connecting pin; Are configured to be rotatably coupled.

  The two-piece boom specification working device expands and contracts the positioning cylinder, so that, for example, the opening angle (folding) between the first boom and the second boom according to the work content such as earth and sand excavation work or building dismantling work. (Angle) can be set appropriately.

  Here, as a working device of the two-piece boom specification according to the prior art, a first positioning cylinder disposed on the upper surface side (rear surface side) of the first boom and a second disposed on the lower surface side (abdominal surface side) of the first boom. A working apparatus having two positioning cylinders with the other positioning cylinder has been proposed.

  In a working device having two positioning cylinders, for example, when a load is applied in the direction of increasing the opening angle between the first boom and the second boom by performing excavation work of earth and sand using a bucket, for example. The high pressure is applied to the bottom side oil chamber of the first positioning cylinder and the rod side oil chamber of the second positioning cylinder. As a result, the two positioning cylinders can secure a force (holding force) for keeping the opening angle of the first and second booms constant, and the first boom and the second boom against the external load. The opening angle with the boom can be kept constant.

  On the other hand, when a load acts in a direction to reduce the opening angle between the first boom and the second boom by performing a dismantling operation or a hanging load operation using a crusher or the like, the rod of the first positioning cylinder Since the side oil chamber and the bottom oil chamber of the second positioning cylinder are at a high pressure, the holding force of the two positioning cylinders can be secured, and the first boom and the second boom are resisted against the load received from the outside. Can be kept constant (for example, see Patent Document 1).

JP 2002-220851 A

  However, the above-described conventional two-piece boom working device requires two positioning cylinders in order to set the opening angle between the first boom and the second boom, and connects these positioning cylinders. Two connecting pins, a connecting pin retaining mechanism, and the like are also required. As a result, there is a problem that the configuration of the working device is complicated and the number of assembly steps is increased, and the manufacturing cost is increased.

  On the other hand, in the working device of the two-piece boom specification in which one positioning cylinder is provided on the lower surface side (abdominal surface side) of the first boom and the second boom, the first boom and the second boom are performed by performing excavation work. When the load acts in the direction in which the opening angle increases (the direction in which the positioning cylinder is extended), the rod-side oil chamber of the positioning cylinder receives a load from the outside due to high pressure.

  However, the rod-side oil chamber has a smaller pressure receiving area of the piston than the bottom-side oil chamber, so that the holding force of the positioning cylinder cannot be sufficiently secured against the load received from the outside. There is a problem that the opening angle with the two booms cannot be kept constant.

  On the other hand, in a two-piece boom specification working device in which one positioning cylinder is provided on the upper surface side (rear surface side) of the first boom and the second boom, the first boom and the second boom are operated by performing the dismantling work and the lifting work. 2 When the load acts in the direction in which the opening angle with the boom is reduced (the direction in which the positioning cylinder is extended), the rod side oil chamber of the positioning cylinder receives a load due to the high pressure. There is a problem that the holding force of the cylinder cannot be sufficiently secured, and the opening angle between the first boom and the second boom cannot be kept constant.

  The present invention has been made in view of the above-described problems of the prior art, and when performing different work such as excavation work, dismantling work, etc. using a work device of a two-piece boom specification, the first boom and the second boom. It is an object of the present invention to provide a construction machine that can maintain a constant opening angle according to the work content.

  In order to solve the above-described problems, the present invention includes a self-propelled vehicle body and a work device provided on the vehicle body so as to be able to move up and down. Provided between the first boom and the second boom, a second boom whose base end side is rotatably connected to a distal end side of the first boom via a boom connecting pin, and The present invention is applied to a construction machine including a positioning cylinder that sets an opening angle of the first and second booms by rotating the second boom about the boom connecting pin.

  A feature of the configuration adopted by the invention of claim 1 is that a first pin mounting hole and a second pin mounting hole on which the boom connecting pin is selectively mounted on the tip side of the first boom according to work contents. The pin mounting holes are arranged at different positions, and the shortest distance between the center of the second pin mounting hole and the axis passing through the center of the tube and rod of the positioning cylinder is set to the first pin mounting hole. It is set larger than the shortest distance between the center of the hole and the axis.

  The invention of claim 2 connects the second boom to the first boom via the boom connecting pin attached to the first pin attachment hole when a load acts on the positioning cylinder in a contracting direction. When a load acts on the positioning cylinder in the extending direction, the second boom is connected to the first boom via the boom connection pin attached to the second pin attachment hole.

  According to the first aspect of the present invention, by connecting the first boom and the second boom via the boom connection pin attached to one of the first pin attachment hole and the second pin attachment hole, the work contents Accordingly, the connection position of the first boom and the second boom can be changed.

  In this case, when the first and second booms are connected via the boom connecting pin attached to the first pin attachment hole, the opening angle of the first and second booms is kept constant against the load received from the outside. The holding force of the positioning cylinder can be expressed by the product of the expansion / contraction force of the positioning cylinder and the shortest distance between the center of the first pin mounting hole and the axis of the positioning cylinder. On the other hand, when the first and second booms are connected via the boom connecting pin attached to the second pin attachment hole, the holding force of the positioning cylinder is the expansion force of the positioning cylinder and the center of the second pin attachment hole. And the shortest distance between the axis of the positioning cylinder.

  Therefore, by selectively attaching the boom connecting pin to one of the first and second pin attaching holes and changing the connecting position of the first and second booms, the first and second loads are resisted against the load received from the outside. The holding force of the positioning cylinder for holding the opening angle of the second boom constant can be appropriately set according to the work content. As a result, the opening angle of the first and second booms can always be kept constant regardless of whether excavation work is performed using the work device or dismantling work. Can be performed smoothly. In addition, the holding force of the positioning cylinder can be set appropriately according to the work content, so the positioning cylinder can be downsized to increase the operating speed, and workability when performing excavation work or dismantling work is improved. Can do.

  According to the second aspect of the present invention, when an external load acts in the contracting direction of the positioning cylinder, the bottom side oil chamber of the positioning cylinder becomes high pressure, so that it acts against the load in the extending direction of the positioning cylinder. Since the force to perform is increased, the holding force of the positioning cylinder can be ensured against the load received from the outside. Therefore, the opening angle of these first and second booms can be kept constant in a state where the first and second booms are connected via the boom connecting pins attached to the first pin attachment holes.

  On the other hand, when a load from the outside acts in the extending direction of the positioning cylinder, the rod side oil chamber of the positioning cylinder becomes high pressure, so that the force acting in the contracting direction of the positioning cylinder against the load is reduced. For this reason, by attaching the boom connecting pin to the second pin mounting hole having the shortest distance from the axis of the positioning cylinder, the force acting in the reduction direction of the positioning cylinder and the center of the second pin mounting hole A large holding force of the positioning cylinder represented by the product of the shortest distance from the axis of the positioning cylinder can be ensured.

  Thus, the positioning cylinder receives from the outside by appropriately changing the mounting position of the boom connecting pin depending on whether the load from the outside acts in the contracting direction of the positioning cylinder or in the extending direction. Since an appropriate holding force can be generated with respect to the load, the opening angle of the first and second booms can always be kept constant, and various operations such as excavation work, dismantling work, and lifting work can be performed smoothly. be able to.

It is a front view which shows the state which the hydraulic excavator by embodiment of this invention performs a disassembly work. It is a principal part enlarged view which shows the connection state of the 1st boom and the 2nd boom at the time of a dismantling operation | work. It is the schematic of the working device which shows the load which acts on a positioning cylinder etc. at the time of dismantling work. It is a front view similar to FIG. 1 which shows the state which a hydraulic excavator performs excavation work. It is a principal part enlarged view which shows the connection state of the 1st boom and the 2nd boom at the time of excavation work. It is the schematic of the working device which shows the load which acts on a positioning cylinder etc. at the time of excavation work.

  Hereinafter, a case where an embodiment of a construction machine according to the present invention is applied to a hydraulic excavator will be described as an example, and will be described in detail with reference to FIGS. 1 to 6.

  Here, FIGS. 1 to 3 show the case where the excavator according to the present embodiment is used for dismantling work such as a building, and FIGS. 4 to 6 show that the excavator according to the present embodiment is used for excavation work such as earth and sand. Shows the case.

  In the figure, reference numeral 1 denotes a hydraulic excavator as a typical example of a construction machine. The hydraulic excavator 1 is mounted on a crawler-type lower traveling body 2 that can be self-propelled and is pivotably mounted on the lower traveling body 2 so that the lower traveling The upper revolving body 3 which comprises a vehicle body with the body 2 and the below-mentioned working apparatus 11 provided in the front part side of the upper revolving body 3 are comprised roughly.

  The upper swing body 3 of the excavator 1 is provided with a swing frame 4 serving as a base that is pivotably mounted on the track frame 2A of the lower traveling body 2, and a cab provided on the left side of the front portion of the swing frame 4. A counterweight 6 provided on the rear end side of the defining cab 5 and on the rear end side of the swivel frame 4 to balance the weight of the working device 11, an engine and a hydraulic pump provided on the front side of the counterweight 6 (not shown) ) And a hydraulic oil tank and a fuel tank (both not shown) provided on the front side of the building cover 7.

  Next, 11 indicates a work device provided on the front side of the upper swing body 3, and the work device 11 is configured as a work piece of a two-piece boom specification, and excavation work such as earth and sand, demolition work such as a building Are used for a plurality of operations. Here, the work device 11 includes a first boom 12, a second boom 14, a boom connecting pin 16, an arm 17, a crusher 19, a boom cylinder 22, a positioning cylinder 23, an arm cylinder 24, a work tool cylinder 25, a first work piece, which will be described later. 1 pin mounting hole 26, second pin mounting hole 27, bucket 28, and the like.

  A first boom 12 is rotatably attached to the front end side of the revolving frame 4, and the first boom 12 constitutes a two-piece boom together with a second boom 14 described later. Here, the first boom 12 includes a left and right side plate 12A facing each other at a constant interval in the left and right directions, and an upper surface plate 12B and a lower surface plate facing each other in the upper and lower directions across the side plate 12A. 12C, it is formed as a rectangular tube having a quadrangular cross section over almost the entire area in the longitudinal direction.

  The base end side of the first boom 12 is pin-coupled to the front end side of the revolving frame 4 via a connecting pin (not shown) so as to be rotatable upward and downward. On the other hand, a pair of left and right boom brackets 13, which will be described later, project from the distal end side of the first boom 12, and a base end side of a second boom 14 which will be described later rotates on the left and right boom brackets 13. It becomes the structure connected so that it is possible. In addition, a cylinder bracket 12D is provided on the distal end side of the bottom plate 12C constituting the first boom 12, and a bottom side of a positioning cylinder 23 described later is attached to the cylinder bracket 12D.

  Reference numeral 13 denotes a pair of left and right brackets (only the left side is shown) projecting from the front end side of the first boom 12, and these left and right boom brackets 13 face each other at regular intervals in the left and right directions. . The left and right boom brackets 13 are provided with a first pin mounting hole 26 and a second pin mounting hole 27, which will be described later, penetrating left and right in different positions.

  Reference numeral 14 denotes a second boom whose base end side is rotatably connected to the distal end side of the first boom 12, and the second boom 14 is raised with respect to the first boom 12 by expansion and contraction of a positioning cylinder 23 described later. It rotates downward. Here, the second boom 14 has left and right side plates 14A facing each other at a constant interval in the left and right directions, and an upper surface plate 14B and a lower surface plate facing each other in the upper and lower directions across the side plates 14A. 14C is formed as a rectangular cylinder having a quadrangular cross section over almost the entire area in the longitudinal direction. The proximal end side of the second boom 14 is inserted between the left and right boom brackets 13 provided on the distal end side of the first boom 12, and is rotated to each boom bracket 13 via a boom connecting pin 16 described later. It is configured to be movably pin-coupled.

  On the other hand, a pair of left and right arm brackets 15 (only the left side is shown) are provided on the distal end side of the second boom 14 so as to face each other at a constant interval in the left and right directions. The base end side of an arm 17 described later is connected to be rotatable. A cylinder bracket 14D to which a bottom side of an arm cylinder 24 described later is attached is provided on the base end side of the upper surface plate 14B constituting the second boom 14, and a positioning cylinder 23 described later is provided on the distal end side of the lower surface plate 14C. A cylinder bracket 14E to which the rod side is attached is provided.

  Reference numeral 16 denotes a boom connecting pin that connects the distal end side of the first boom 12 and the proximal end side of the second boom 14, and the boom connecting pin 16 is a boom bracket provided on the distal end side of the first boom 12. The second boom 14 is pivotally connected to 13. Here, the boom connection pin 16 is selectively attached to either one of a first pin attachment hole 26 and a second pin attachment hole 27 described later provided in the left and right boom brackets 13. Thus, the mounting position of the second boom 14 with respect to the first boom 12 can be changed according to the work content.

  Reference numeral 17 denotes an arm that is rotatably connected to the distal end side of the second boom 14, and the arm 17 is a rectangular tube having a square cross section surrounded by left and right side plates, an upper surface plate, and a lower surface plate. It is formed as. A cylinder bracket 17A to which an arm cylinder 24 described later is attached is provided on the proximal end side of the arm 17, and a cylinder bracket 17B to which a work tool cylinder 25 described later is attached is provided on the upper surface on the proximal end side of the arm 17. It has been.

  Reference numeral 18 denotes an arm connecting pin for connecting the distal end side of the second boom 14 and the arm 17, and the arm connecting pin 18 includes left and right arm brackets 15 provided on the distal end side of the second boom 14, and The arm 17 is inserted into a boss portion (not shown) provided on the base end side. As a result, the distal end side of the arm 17 is configured to rotate upward (downward and downward) with respect to the second boom 14 about the arm connecting pin 18.

  Reference numeral 19 denotes a crusher as a working tool rotatably attached to the distal end side of the arm 17, and the crusher 19 is used to disassemble a building using the work device 11 as shown in FIG. 17 is attached to the tip side. Here, the crusher 19 has left and right claw members 19A that are opened and closed by a hydraulic cylinder. The left and right claw members 19A crush the building and the like, and lift the crushed waste material 100 for transportation. It is transported to a vehicle or the like (not shown). A bracket 19B is provided on the proximal end side of the crusher 19, and the bracket 19B is attached to the distal end side of the arm 17 via a work tool connecting pin 20. A bucket link 21 is provided between the bracket 19 </ b> B and the arm 17, and a rod side of a work tool cylinder 25 described later is connected to an intermediate portion of the bucket link 21.

  A boom cylinder 22 is provided between the revolving frame 4 and the first boom 12, and the boom cylinder 22 is arranged on the left and right with the first boom 12 interposed therebetween. The boom cylinder 22 rotates the first boom 12 upward and downward with respect to the revolving frame 4.

  Reference numeral 23 denotes a positioning cylinder provided between the first boom 12 and the second boom 14, and the positioning cylinder 23 sets an opening angle between the first boom 12 and the second boom 14. Here, as shown in FIG. 3, the positioning cylinder 23 includes a tube 23A, a piston 23B slidably provided in the tube 23A, a proximal end side attached to the piston 23B, and a distal end side outside the tube 23A. The tube 23A is roughly constituted by the protruding rod 23C, and the inside of the tube 23A is defined by a bottom side oil chamber 23D and a rod side oil chamber 23E by a piston 23B. In the positioning cylinder 23, the bottom side of the tube 23A is pin-coupled to the cylinder bracket 12D of the first boom 12, and the tip side of the rod 23C is pin-coupled to the cylinder bracket 14E of the second boom 14.

  Therefore, the angle between the first boom 12 and the second boom 14 around the boom connecting pin 16, that is, the first boom 12 and the second boom, according to the amount of expansion and contraction of the positioning cylinder 23 (projection length of the rod 23C). The opening angle (bending angle) with the boom 14 can be set as appropriate. When excavation work or dismantling work is performed using the work device 11, the positioning cylinder 23 resists loads acting on the extending direction or the reducing direction of the positioning cylinder 23 from the outside, and the first boom 12 and the second boom. 14 generates a force (holding force) for keeping the opening angle with respect to 14 constant.

  Reference numeral 24 denotes an arm cylinder provided between the second boom 14 and the arm 17. The arm cylinder 24 is connected to the cylinder bracket 14 </ b> D of the second boom 14 on the bottom side and connected to the cylinder bracket 17 </ b> A of the arm 17 on the rod side. Has been. Accordingly, the arm 17 can be rotated upward and downward on the tip end side of the second boom 14 by extending and contracting the arm cylinder 24.

  A work tool cylinder 25 is provided between the arm 17 and the bucket link 21, and the work tool cylinder 25 is pin-coupled to the cylinder bracket 17 </ b> B of the arm 17 on the bottom side and is pinned to an intermediate portion of the bucket link 21 on the rod side. Are combined. Accordingly, the crusher 19 is rotated upward and downward on the distal end side of the arm 17 by expanding and contracting the work tool cylinder 25.

  Next, 26 indicates a first pin mounting hole provided on the distal end side of the first boom 12, and the first pin mounting hole 26 is formed on a building or the like by using a crusher 19 as shown in FIG. When the dismantling operation is performed, a boom connecting pin 16 that connects the first boom 12 and the second boom 14 is attached.

  The first pin mounting holes 26 are provided through the left and right boom brackets 13 located on the distal end side of the first boom 12 in the left and right directions. The first boom 12 and the second boom 14 are connected via the boom connection pin 16 by inserting both end sides of the boom connection pin 16 inserted through the proximal end side of the second boom 14. ing.

  Reference numeral 27 denotes a second pin attachment hole provided on the distal end side of the first boom 12 at a position spaced from the first pin attachment hole 26. The second pin attachment hole 27 is, for example, as shown in FIG. When excavation work such as earth and sand is performed using a bucket 28 described later, a boom connecting pin 16 that connects the first boom 12 and the second boom 14 is attached.

  The second pin mounting holes 27 are also provided penetrating left and right in the left and right boom brackets 13 located on the distal end side of the first boom 12. The first boom 12 and the second boom 14 are connected via the boom connection pin 16 by inserting both end sides of the boom connection pin 16 inserted through the proximal end side of the second boom 14. ing.

  Here, as shown in FIGS. 2 and 5, the axis passing through the center of the tube 23A and the rod 23C of the positioning cylinder 23 is O1-O1, and the center of the first pin mounting hole 26 and the axis O1-O1 are If the shortest distance between them is L1, and the shortest distance between the center of the second pin mounting hole 27 and the axis O1-O1 is L2, the distance L2 is set larger than the distance L1 (L2>). L1).

  In this case, the shortest distance L1 between the center of the first pin mounting hole 26 and the axis O1-O1 is from the center of the first pin mounting hole 26 to the axis O1-O1, as shown in FIG. This is expressed as the length of the lowered vertical line X1. The shortest distance L2 between the center of the second pin mounting hole 27 and the axis O1-O1 is the length of the perpendicular line X2 extending from the center of the second pin mounting hole 27 to the axis O1-O1. It is represented.

  Next, FIG. 4 shows a case where the excavator 1 is used for excavation work such as earth and sand. In this case, instead of the crusher 19 for dismantling work shown in FIG. 1, a bucket 28 for excavation work is attached to the tip side of the arm 17.

  A bracket 28 </ b> A is provided on the proximal end side of the bucket 28, and the bracket 28 </ b> A is attached to the distal end side of the arm 17 via a work tool connecting pin 20. A bucket link 21 is provided between the bracket 28 </ b> A and the arm 17. Accordingly, the bucket 28 rotates upward and downward on the tip end side of the arm 17 by expanding and contracting the work tool cylinder 25.

  Thus, the hydraulic excavator 1 according to the present embodiment is used for dismantling work such as a building when the crusher 19 is attached to the distal end side of the arm 17 as shown in FIG. 1, and as shown in FIG. When the bucket 28 is attached to the distal end side of the arm 17, it is used for excavation work such as earth and sand.

  Here, when the dismantling work is performed using the hydraulic excavator 1, that is, when a load acts on the positioning cylinder 23 in a contracting direction as will be described later, as shown in FIGS. 26, the boom connecting pin 16 is attached, and the first boom 12 and the second boom 14 are connected via the boom connecting pin 16.

  In this case, the waste material 100 is lifted by the crusher 19 in a state where the opening angle of the first and second booms 12 and 14 is set to θ1 by the positioning cylinder 23, whereby a downward load A1 is applied to the distal end side of the working device 11. When acting, the load B1 acts on the positioning cylinder 23 in the direction of decreasing the opening angle θ1 of the first and second booms 12 and 14 (the reduction direction of the positioning cylinder 23).

  On the other hand, the holding force F1 for keeping the opening angle θ1 constant against the load B1 during the dismantling operation is the pressure in the bottom side oil chamber 23D of the positioning cylinder 23 as shown in FIG. Is expressed as follows as the product of the stretching force C1 acting in the extending direction and the shortest distance L1 between the center of the first pin mounting hole 26 and the axis O1-O1 of the positioning cylinder 23.

  In this case, since the pressure receiving area of the piston 23B in the bottom side oil chamber 23D of the positioning cylinder 23 is larger than the pressure receiving area of the piston 23B in the rod side oil chamber 23E, the expansion / contraction force C1 acting in the extending direction of the positioning cylinder 23 is large. Become. As a result, a large holding force F1 of the positioning cylinder 23 during the dismantling operation represented by the above equation 1 can be secured, and the opening angle θ1 of the first and second booms 12 and 14 during the dismantling operation can be kept constant. The configuration can be maintained.

  On the other hand, when excavation work is performed using the hydraulic excavator 1, that is, when a load is applied to the positioning cylinder 23 in the extending direction as will be described later, as shown in FIGS. A boom connecting pin 16 is attached to the first boom 12 and the second boom 14 via the boom connecting pin 16.

  In this case, in a state where the opening angle of the first and second booms 12 and 14 is set to θ2 by the positioning cylinder 23, the excavation reaction force when excavating the hard ground by the bucket 28 is directed forward to the front end side of the work device 11. When the load A2 is applied, the load B2 is applied to the positioning cylinder 23 in the direction of increasing the opening angle θ2 of the first and second booms 12 and 14 (the extending direction of the positioning cylinder 23).

  On the other hand, the holding force F2 for keeping the opening angle θ2 constant against the load B2 during excavation work is the pressure in the rod-side oil chamber 23E of the positioning cylinder 23 as shown in FIG. Is expressed as follows as the product of the expansion / contraction force C2 acting in the reduction direction and the shortest distance L2 between the center of the second pin mounting hole 27 and the axis O1-O1 of the positioning cylinder 23.

  In this case, since the pressure receiving area of the piston 23B in the rod side oil chamber 23E of the positioning cylinder 23 is smaller than the pressure receiving area of the piston 23B in the bottom side oil chamber 23D, the expansion / contraction force C2 acting in the reduction direction of the positioning cylinder 23 is It becomes smaller than the stretching force acting in the extension direction.

  On the other hand, the shortest distance L2 between the center of the second pin mounting hole 27 and the axis O1-O1 of the positioning cylinder 23 is the center of the first pin mounting hole 26 and the axis O1-O1 of the positioning cylinder 23. It is set larger than the shortest distance L1 between. As a result, a large holding force F2 of the positioning cylinder 23 at the time of excavation represented by the above equation 2 can be secured, and the opening angle θ2 of the first and second booms 12 and 14 at the time of excavation can be kept constant. The configuration can be maintained.

  The hydraulic excavator 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described below.

  First, as shown in FIGS. 1 and 2, when the excavator 1 is used to dismantle a building or the like, the boom is connected to the first pin mounting hole 26 provided in the boom bracket 13 of the first boom 12. A pin 16 is attached, and the first boom 12 and the second boom 14 are connected via the boom connecting pin 16.

  Then, the positioning cylinder 23 provided between the first boom 12 and the second boom 14 is expanded and contracted to set a constant opening angle θ1 between the first boom 12 and the second boom 14. A crusher 19 is attached to the tip end side of the arm 17.

  In this state, the first and second booms 12 and 14 are rotated by the boom cylinder 22, the arm 17 is rotated by the arm cylinder 24, the building or the like is crushed by the crusher 19, and the crushed waste material 100 is lifted. By transporting it to a transportation vehicle or the like, the excavator 1 can be used to dismantle a building or the like.

  By the way, at the time of the above-described dismantling operation, the crushed waste material 100 is lifted by the crusher 19 and transported to a transport vehicle or the like, so that the tip of the work device 11 depends on the weight of the waste material 100 or the weight of the work device 11 as shown in FIG. A downward load A1 acts on the side, and a load B1 in the reduction direction acts on the positioning cylinder 23.

  Here, the holding force F1 for the positioning cylinder 23 to keep the opening angle θ1 of the first and second booms 12 and 14 constant against the load B1 in the shrinking direction is determined by the above-described equation (1). The product of the expansion / contraction force C1 acting in the extending direction due to the pressure in the bottom side oil chamber 23D and the shortest distance L1 between the center of the first pin mounting hole 26 and the axis O1-O1 of the positioning cylinder 23 Represented as:

  In this case, since the pressure receiving area of the piston 23B in the bottom side oil chamber 23D of the positioning cylinder 23 is larger than the pressure receiving area of the piston 23B in the rod side oil chamber 23E, the expansion / contraction force C1 acting in the extending direction of the positioning cylinder 23 is large. Thus, a large holding force F1 of the positioning cylinder 23 can be secured. As a result, even if a load B1 in the reduction direction acts on the positioning cylinder 23 during the dismantling operation, the positioning cylinder 23 sets the opening angle θ1 of the first and second booms 12 and 14 against this load B1. Can be kept constant.

  As a result, when the disassembly work is performed using the work device 11, the opening angle θ1 between the first boom 12 and the second boom 14 can be always kept constant by the single positioning cylinder 23. Work can be performed smoothly.

  Moreover, the shortest distance L1 between the center of the first pin mounting hole 26 and the axis O1-O1 of the positioning cylinder 23 is between the center of the second pin mounting hole 27 and the axis O1-O1 of the positioning cylinder 23. It is set smaller than the shortest distance L2 between them.

  Therefore, the opening angle θ1 between the first boom 12 and the second boom 14 when the boom connecting pin 16 is attached to the first pin attaching hole 26 is determined by attaching the boom connecting pin 16 to the second pin attaching hole 27. The opening angle θ2 between the first boom 12 and the second boom 14 can be set larger. As a result, the work range (movable range) of the work device 11 during the dismantling work can be expanded, and the workability can be further enhanced.

  Next, as shown in FIGS. 4 and 5, when excavation work such as earth and sand is performed using the excavator 1, the boom is inserted into the second pin mounting hole 27 provided in the boom bracket 13 of the first boom 12. A connecting pin 16 is attached, and the first boom 12 and the second boom 14 are connected via the boom connecting pin 16.

  Then, by extending and retracting a positioning cylinder 23 provided between the first boom 12 and the second boom 14, a constant opening angle θ2 is set between the first boom 12 and the second boom 14. In addition, a bucket 28 for excavation work is attached to the distal end side of the arm 17 instead of the crusher 19 for dismantling work.

  In this state, the excavator 1 is used by excavating the ground by the bucket 28 while rotating the first and second booms 12 and 14 by the boom cylinder 22 and rotating the arm 17 by the arm cylinder 24. Excavation work such as earth and sand can be performed.

  By the way, during the excavation work described above, a forward load A2 acts on the distal end side of the working device 11 due to the excavation reaction force when the hard ground is excavated by the bucket 28, and the positioning cylinder 23 is affected. Thus, the load B2 in the extending direction acts.

  Here, the holding force F2 for the positioning cylinder 23 to keep the opening angle θ2 of the first and second booms 12 and 14 constant against the load B2 in the extending direction is determined by the above-described formula 2. The product of the expansion / contraction force C2 acting in the contracting direction due to the pressure in the rod side oil chamber 23E and the shortest distance L2 between the center of the second pin mounting hole 27 and the axis O1-O1 of the positioning cylinder 23 Represented as:

  In this case, since the pressure receiving area of the piston 23B in the rod side oil chamber 23E of the positioning cylinder 23 is smaller than the pressure receiving area of the piston 23B in the bottom side oil chamber 23D, the expansion / contraction force C2 acting in the reduction direction of the positioning cylinder 23 is It becomes smaller than the stretching force acting in the extension direction.

  However, the shortest distance L2 between the center of the second pin mounting hole 27 and the axis O1-O1 of the positioning cylinder 23 is the shortest distance between the center of the first pin mounting hole 26 and the axis O1-O1. It is set larger than the distance L1. Therefore, even when the expansion / contraction force C2 acting in the reduction direction of the positioning cylinder 23 is small, the expansion / contraction force C2 of the positioning cylinder 23 and the shortest distance between the center of the second pin mounting hole 27 and the axis O1-O1. A large holding force F2 of the positioning cylinder 23 that is a product of the distance L2 can be secured.

  As a result, even if a load B2 in the extending direction acts on the positioning cylinder 23 during excavation work, the positioning cylinder 23 sets the opening angle θ2 of the first and second booms 12 and 14 against this load B2. It can be kept constant and excavation work can be performed smoothly.

  In addition, since the positioning cylinder 23 can keep the opening angle θ2 of the first and second booms 12 and 14 constant against the load B2 in the extending direction, it is not necessary to increase the size of the positioning cylinder 23. Thereby, since the small positioning cylinder 23 can be used and the operating speed can be raised, workability | operativity at the time of dismantling work or excavation work can be improved further.

  Thus, according to the present embodiment, when the first bracket mounting hole 26 and the second pin mounting hole 27 are provided in the boom bracket 13 of the first boom 12, and the disassembly work is performed, the first pin mounting When the first boom 12 and the second boom 14 are connected via the boom connection pin 16 attached to the hole 26 and excavation work is performed, the first boom 12 is attached via the boom connection pin 16 attached to the second pin attachment hole 27. The first boom 12 and the second boom 14 are connected to each other.

  Thereby, when the load B1 is applied in the shrinking direction of the positioning cylinder 23 during the dismantling operation, the expansion / contraction force C1 acting in the extending direction of the positioning cylinder 23 against the load B1 and the center of the first pin mounting hole 26 And the minimum distance L1 between the positioning cylinder 23 and the axis O1-O1 of the positioning cylinder 23 can ensure a large holding force F1 of the positioning cylinder 23, and the opening angle between the first boom 12 and the second boom 14 θ1 can be kept constant.

  On the other hand, when the load B2 is applied in the extending direction of the positioning cylinder 23 during excavation work, the expansion / contraction force C2 acting in the contracting direction of the positioning cylinder 23 against the load B2 and the center of the second pin mounting hole 27 The product of the positioning cylinder 23 and the shortest distance L2 between the axis O1-O1 can secure a large holding force F2 of the positioning cylinder 23, and the opening angle θ2 between the first boom 12 and the second boom 14 can be secured. Can be kept constant.

  As described above, the positioning cylinder 23 can be externally changed by appropriately changing the mounting position of the boom connecting pin 16 between when the load is applied in the contracting direction of the positioning cylinder 23 and when the load is applied in the extending direction. A proper holding force can always be secured with respect to the load received from the. As a result, since the opening angle between the first boom 12 and the second boom 14 can be kept constant regardless of the work content, various work such as excavation work and dismantling work can be performed smoothly. Can be increased.

  Further, the positioning cylinder 23 can keep the opening angle between the first boom 12 and the second boom 14 constant regardless of whether the load from the outside acts in the contracting direction or the extending direction. There is no need to increase the size of the positioning cylinder 23. As a result, the positioning cylinder 23 can be reduced in size and its operating speed can be increased, so that workability when performing dismantling work or excavation work can be further improved.

  In addition, in embodiment mentioned above, the case where the crusher 19 is attached to the front end side of the arm 17 and the dismantling work is illustrated as a case where the boom connecting pin 16 is attached to the second pin attachment hole 27. However, the present invention is not limited to this. For example, even when a clamshell bucket, a lifting magnet, or the like is attached to the distal end side of the arm 17 to perform a lifting work, the boom connecting pin 16 is inserted into the second pin attachment hole 27. Can be installed.

  In the above-described embodiment, the hydraulic excavator 1 having a crawler type lower traveling body is described as an example of the construction machine. However, the present invention is not limited to this, and can be applied to, for example, a wheeled hydraulic excavator having wheels.

1 Excavator (construction machine)
2 Lower traveling body (car body)
3 Upper swing body (car body)
DESCRIPTION OF SYMBOLS 11 Work apparatus 12 1st boom 14 2nd boom 16 Boom connection pin 17 Arm 19 Crusher 23 Positioning cylinder 23A Tube 23C Rod 26 1st pin attachment hole 27 2nd pin attachment hole 28 Bucket

Claims (2)

The vehicle includes a self-propelled vehicle body and a work device provided on the vehicle body so as to be able to move up and down. The work device includes a first boom whose base end side is rotatably connected to the vehicle body, A second boom pivotably connected to a tip end side of the first boom via a boom connecting pin; and the second boom provided between the first boom and the second boom. In a construction machine comprising a positioning cylinder that sets an opening angle of the first and second booms by turning as a center,
A first pin mounting hole and a second pin mounting hole to which the boom connecting pin is selectively mounted according to the work content are disposed at different positions on the distal end side of the first boom,
The shortest distance between the center of the second pin mounting hole and the axis passing through the center of the tube and rod of the positioning cylinder is the shortest distance between the center of the first pin mounting hole and the axis. A construction machine characterized in that it is configured to be larger than that. When a load acts on the positioning cylinder in a contracting direction, the second boom is connected to the first boom via the boom connection pin attached to the first pin attachment hole,
2. The structure according to claim 1, wherein when a load is applied to the positioning cylinder in an extending direction, the second boom is connected to the first boom via the boom connection pin attached to the second pin attachment hole. Construction machinery.

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