WO2024062792A1

WO2024062792A1 - Hydraulic lifting/lowering device

Info

Publication number: WO2024062792A1
Application number: PCT/JP2023/029045
Authority: WO
Inventors: 敏和川本; 松井　保憲; 祐輝大嶽; 大樹東畠; 央塚谷
Original assignee: 株式会社クボタ
Priority date: 2022-09-20
Filing date: 2023-08-09
Publication date: 2024-03-28
Also published as: JP2024043765A

Abstract

Provided is a hydraulic lifting/lowering device that can easily increase the separation distance between a coupled implement and the ground. The hydraulic lifting/lowering device 100 can execute draft control and comprises a lift arm 2, a bracket 3, a draft control lever 8, and a draft control transmission mechanism 40. The bracket 3 is provided on a rear end portion of a case 1 and rotates, using the other-end side 32 of the bracket 3 as a fulcrum, relative to the case 1 in accordance with the draft load from a coupled top link. Additionally, the bracket 3 includes attachment parts 35a-c, 36a-c that are configured to enable the attachment of a front-side end of the top link. In the lifting/lowering direction of the implement, the bracket axis Z2 is positioned higher than the lift arm axis Z1, and the attachment parts 35a-c, 36a-c, which have the axes Z3, Z4, and Z5, are positioned lower than the bracket axis Z2.

Description

Hydraulic lifting device

The present invention relates to a hydraulic lifting device that lifts and lowers a lift arm based on hydraulic pressure.

Conventionally, a hydraulic lifting device that raises and lowers a lift arm based on hydraulic pressure is known, for example, as shown in Patent Document 1. This device is equipped with a hydraulic cylinder and a control valve having a spool, and the supply and discharge of hydraulic oil to the hydraulic cylinder is permitted and regulated depending on the position of the spool. This device also includes a load detection member and a biasing mechanism. The load detection member is provided at the rear end of the transmission case, and is connectable to the front end of the top link. The load detection member is also capable of swinging in response to the towing load of the implement via the top link. The biasing mechanism biases the load detection member to swing.

When the load detection member swings in response to the traction load, the spool is displaced in response to the swing via the transmission mechanism. Then, the lift arm moves up and down with the implement connected. As a result, implements such as plows can also be raised and lowered, and an appropriate tractive load can be maintained. That is, the above-described configuration allows draft control to be executed.

JP 2018-153118 A (paragraph 0039, FIG. 3, etc.)

A top link connected to this type of hydraulic lifting device generally has a rod shape, with a front end side and a rear end side defined. When the front end side of the top link is connected to the attachment part of the hydraulic lifting device, the rear end side is located above the front end side. Here, if the height, arm length, and rotation range of the lift arm rotation axis remain the same, the more the front end position of the top link moves downward when the implement is connected, the more the implement The lower edge of is raised higher. That is, the distance between the connected implement and the ground becomes larger. Therefore, by locating the front end of the top link further downward, the distance between the connected implement and the ground can be increased, which is often preferable when operating a working machine.

On the other hand, the load detection member of Patent Document 1 mentioned above includes a connection hole and a support shaft. The connecting hole is configured to connect the front end side of the top link. The support shaft swingably supports the load detection member at the rear end of the transmission case. Regarding the positional relationship between the connection hole and the support shaft, the connection hole is located above the support shaft. For this reason, the front end side of the top link cannot be positioned sufficiently downward, and it is difficult to increase the distance between the connected implement and the ground.

Therefore, in view of the above, an object of the present invention is to provide a hydraulic lifting device that can easily increase the distance between a connected implement and the ground.

The technical means of the present invention for solving this technical problem is characterized by the following points. The hydraulic lifting device of the present invention includes a case, a hydraulic cylinder located inside the case and driven according to the supply and discharge of hydraulic oil, and a spool located inside the case and arranged in a flow path for the hydraulic oil. a control valve that allows and regulates supply and discharge of the hydraulic oil to the hydraulic cylinder according to the position of the spool; and a control valve that is located outside the case and has one end and the other end. The lift arm is configured such that the one end side can be connected to an object, and when the hydraulic cylinder is driven, the other end side rotates relative to the case with the other end side as a fulcrum. a lift arm configured to be able to lift and lower the object, and a bracket located outside the case and defined with one end and the other end, the one end being configured to be connectable to the object. a bracket that rotates relative to the case using the other end as a fulcrum in response to a traction load from the connected object; and a bracket that is located outside the case and is displaced in response to an operator's operation. a draft control lever configured to be able to control the draft; a draft feedback rod that is located outside the case and configured to be displaceable in accordance with relative rotation of the bracket; The displacement of the control lever is transmitted toward the spool, and the position of the spool is displaced toward a side that allows supply and discharge of the hydraulic oil, and when the bracket rotates relative to the other, the displacement of the draft feedback rod is transmitted. The draft control transmission mechanism includes a draft control transmission mechanism that transmits the transmission toward the spool and displaces the position of the spool toward a side that regulates supply and discharge of the hydraulic oil. The lift arm includes a lift arm axis that is an axis of the relative rotation with respect to the case and that extends in a second direction perpendicular to a first direction that is a lifting direction of the object; The axis of relative rotation with respect to the case is an axis extending in the second direction, and is configured to be able to attach the object to a bracket axis located parallel to the lift arm axis, and is configured such that the object can be attached to the bracket axis. and a mounting portion located on the lower side in the first direction.

In the hydraulic lifting device, the bracket is configured such that the bracket axis is located lower than the lift arm axis in the first direction.

In the hydraulic lifting device, the bracket is configured such that the bracket axis is located above the lift arm axis in the first direction.

The hydraulic lifting device is a shaft that pivotally supports the other end of the bracket on the case and is arranged coaxially with the bracket shaft, and generates a biasing force during relative rotation according to the traction load. The apparatus further includes a bracket shaft configured to do so.

In the hydraulic lifting device, the draft control transmission mechanism includes a first draft control shaft that rotates about its axis in response to the displacement of the draft control lever when the draft control lever is operated, a second draft control shaft that is located above the first draft control shaft in the lifting direction of the object and rotates about its axis in response to the displacement of the draft feedback rod when the bracket rotates relative to the first draft control shaft, and a draft control cam that displaces the position of the spool toward the allowable side of the supply and discharge of the hydraulic oil in response to the rotation of the first draft control shaft when the first draft control shaft rotates, and displaces the position of the spool toward the restrictive side of the supply and discharge of the hydraulic oil in response to the rotation of the second draft control shaft when the second draft control shaft rotates.

In the hydraulic lifting device, the draft control lever has one end and the other end, the one end is operable by the operator, and the other end is used as a fulcrum for displacement according to the operation. The first draft control shaft is connected to the other end of the draft control lever and is configured to be rotatable in the same direction as the rotation direction of the draft control lever. a same-direction rotating shaft; a reverse-rotating shaft connected to the draft control cam and configured to be rotatable in a direction opposite to the rotational direction of the draft control lever; and when the draft control lever relatively rotates, the A rotation transmitting unit that transmits the rotation of the same direction rotating shaft to the opposite direction rotating shaft and rotates the opposite direction rotating shaft in a direction opposite to the rotation direction of the same direction rotating shaft.

The hydraulic lifting device includes a position control lever located outside the case and configured to be displaceable according to an operation by an operator, and a position control lever located outside the case and configured to be displaced according to relative rotation of the lift arm. a position feedback rod configured to transmit a displacement of the position control lever toward the spool when the position control lever is operated, and a position feedback rod configured to allow the position of the spool to be supplied and discharged in the hydraulic fluid; and transmits the displacement of the position feedback rod toward the spool when the lift arm relatively rotates, and the position of the spool is directed toward a side that regulates supply and discharge of the hydraulic oil. A position control transmission mechanism for causing displacement. The position control transmission mechanism includes a first position control shaft that rotates around an axis in response to displacement of the position control lever when the position control lever is operated, and a first position control shaft that rotates around the axis in response to displacement of the position control lever; a second position control shaft that is located on the upper side in the vertical direction of the lift arm and rotates around an axis according to the displacement of the position feedback rod when the lift arm rotates relative to the second position control shaft; and when the first position control shaft rotates. In accordance with the rotation of the first position control shaft, the position of the spool is displaced toward a side where supply and discharge of the hydraulic oil is permitted, and when the second position control shaft rotates, the second position control shaft is moved. The apparatus further includes a position control cam that displaces the position of the spool toward a side that regulates supply and discharge of the hydraulic oil in accordance with rotation of the shaft.

The hydraulic lifting device is connected to the second draft control shaft so as to be integrally rotatable, and is also connected to the draft feedback rod so as to be relatively rotatable, and when the bracket rotates relative to the bracket, the hydraulic lifting device responds to the displacement of the draft feedback rod. Accordingly, a first displacement transmitting section that rotates the second draft control shaft is connected to the second position control shaft so as to be integrally rotatable, and is connected to the position feedback rod so as to be relatively rotatable, and the lift arm a second displacement transmitting part that rotates the second position control shaft according to the displacement of the position feedback rod when the position feedback rod rotates relative to the second position control shaft; The second displacement transmitting section is configured to rotate relative to the case in conjunction with the rotation of the second displacement transmitting section, and when the position feedback rod is displaced and the second displacement transmitting section rotates, the second displacement transmitting section rotates relative to the case. The apparatus further includes a third displacement transmitting part that rotates the first displacement transmitting part by pressing the first displacement transmitting part while contacting the first displacement transmitting part.

In the hydraulic lifting device, one of the first draft control shaft and the first position control shaft has a hollow structure, and the other is configured to be coaxially fit into the inside of the one. , the second draft control shaft, and the second position control shaft have a hollow structure and are configured such that the other can be coaxially fitted into the inside of the one, and the draft control transmission The mechanism and the position control transmission mechanism are such that the other is coaxially fitted into one of the first draft control shaft and the first position control shaft, and the other is coaxially fitted into one of the first draft control shaft and the second position control shaft. The other position control shaft is coaxially fitted into one of the position control shafts, and the first draft control shaft and the first position control are moved in response to displacement of either one of the draft control lever and the position control lever. The shafts rotate relative to each other around the axis, and the second draft control shaft and the second position control shaft rotate relative to each other around the axis in response to displacement of either one of the draft feedback rod and the position feedback rod. configured to rotate.

The hydraulic lifting device is located outside the case, and is moved in response to an operator's operation from a first position that is an arbitrary position when supply and discharge of the hydraulic oil is regulated by the control valve. , a pumper lever configured to be able to be displaced to a second position different from the first position; and a pumper lever that is configured to be displaced from the first position to the second position. The transmission is transmitted toward the spool, and the position of the spool is displaced toward a side where supply and discharge of the hydraulic oil is permitted, and the lift arm is rotated relative to the pump lever in the second position. The pump transmission mechanism further includes a pump transmission mechanism that transmits the displacement of the position feedback rod toward the spool and displaces the position of the spool toward a side that restricts supply and discharge of the hydraulic oil. The pumper transmission mechanism includes a pumper shaft that rotates around an axis in accordance with displacement of the pumper lever, and a pumper shaft that rotates when the pumper lever is operated and displaced from the first position to the second position. When the pump shaft rotates, the position of the spool is displaced toward a side that allows supply and discharge of the hydraulic oil, and when the second position control shaft rotates, the second position control shaft a pump cam that displaces the position of the spool toward a side that regulates supply and discharge of the hydraulic oil in response to rotation of the pump cam.

In the hydraulic lifting device, the pumper lever has one end and the other end, the one end is operable by the operator, and the pumper lever is configured to be displaced in accordance with the operation with the other end as a fulcrum. The pump lever includes a rotation regulating portion configured to be rotatable relative to the case and regulating the relative rotation of the pumper lever.

According to the present invention, the distance between the connected implement and the ground can be easily increased.

1 is an overall perspective view of a hydraulic lifting device according to a first embodiment of the present invention. FIG. 2 is a right side view of the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is a left side view of the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is a bottom view of the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is a perspective view showing a part of the drive system inside the case of the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is a perspective view showing a part of the drive system inside the case of the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is a left side view of the rear side of the hydraulic lifting device shown in FIG. 1, and is a diagram showing the positional relationship of each axis. 2 is an overall perspective view of each transmission mechanism in the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is an enlarged view of essential parts showing the positional relationship of each cam and spool in the hydraulic lifting device shown in FIG. 1. FIG. 2 is an overall view of a position control transmission mechanism in the hydraulic lifting device shown in FIG. 1. FIG. 2 is an overall view of a pump transmission mechanism in the hydraulic lifting device shown in FIG. 1. FIG. 2 is an overall view of a draft control transmission mechanism in the hydraulic lifting device shown in FIG. 1. FIG. FIG. 2 is an overall schematic diagram showing the positional relationship of the components of each transmission mechanism in the hydraulic lifting device shown in FIG. 1. FIG. FIG. 6 is a left side view of a hydraulic lifting device according to a second embodiment of the present invention. FIG. 15 is a left side view of the rear side of the hydraulic lifting device shown in FIG. 14, and is a diagram showing the positional relationship of each axis. 15 is a perspective view showing the configuration near the front end of each feedback rod in the hydraulic lifting device shown in FIG. 14. FIG. 15 is an overall schematic diagram showing the positional relationship of the components of each transmission mechanism in the hydraulic lifting device shown in FIG. 14. FIG. 15 is a component configuration diagram of a position feedback rod, a second displacement transmission mechanism, a third displacement transmission mechanism, and a fourth displacement transmission mechanism in the hydraulic lifting device shown in FIG. 14. FIG. 15 is a component configuration diagram of a draft feedback rod and a first displacement transmission mechanism in the hydraulic lifting device shown in FIG. 14. FIG.

Hereinafter, each embodiment of the present invention will be described based on the drawings.

[First embodiment]
First, a first embodiment of the present invention will be described.

<Overall configuration of hydraulic lifting device>
FIG. 1 is an overall perspective view of a hydraulic lifting device 100 according to a first embodiment of the present invention. 2 and 3 are side views of the hydraulic lifting device 100. FIG. 4 is a bottom view of the hydraulic lifting device 100. Left/right, up/down, front/back of the arrows appropriately shown in each figure correspond to left/right direction, upward/downward direction, and front/backward direction, respectively.

The hydraulic lifting device 100 is mounted, for example, on an agricultural vehicle such as a tractor. More specifically, the hydraulic lifting device 100 is mounted at the rear of a tractor or the like and above the transmission case. One end side 21 of the lift arm 2 and one end side 31 of the bracket 3 protrude rearward from the mounted hydraulic lifting device 100. One end 21 of the lift arm 2 is connected to a lower link via a lift link. An end of a top link is connected to one end 31 of the bracket 3. An implement is connected to the rear of the top link and the lower link. As the lift arm 2 rotates relative to the case 1, the connected implement can be raised and lowered in the vertical direction relative to the agricultural vehicle via the top link and the lower link. In this embodiment, the up-and-down direction of the implement corresponds to the up-down direction, and corresponds to the first direction.

As shown in FIGS. 1 to 4, the hydraulic lifting device 100 includes a case 1, a lift arm 2, a lift arm shaft 23, a bracket 3, a bracket shaft 33, a hydraulic cylinder 4, a control valve 5, a position control lever 6, and a pumper lever. 7, a draft control lever 8, a position feedback rod 9, and a draft feedback rod 10. The bracket 3 will be detailed later. The hydraulic lifting device 100 also includes a position control transmission mechanism 20, a pump transmission mechanism 30, and a draft control transmission mechanism 40. Each

transmission mechanism

20, 30, 40 will also be explained in detail later.

Case 1 is a housing, and the bottom of case 1 is open. The two lift arms 2 are located at the rear outside of the case 1, one each on both left and right sides. In each lift arm 2, one end side 21 and the other end side 22 are defined. One end side 21 is configured to be connectable to a lift link (not shown). The other end side 22 is pivotally supported at both ends of a lift arm shaft 23 that passes through both left and right side surfaces from inside the case 1 (see FIGS. 5 and 6). Each lift arm 2 projects rearward from the other end side 22 toward the one end side 21. Each lift arm 2 rotates relative to the case 1 using the other end side 22 as a fulcrum when the hydraulic cylinder 4 is driven. That is, the one end side 21 can swing vertically using the other end side 22 as a fulcrum.

As shown in FIGS. 1, 5, and 6, the lift arm 2 includes a lift arm axis Z1 that is an axis of relative rotation with respect to the case 1. In this embodiment, the direction of the lift arm axis Z1 corresponds to the left-right direction, and corresponds to the second direction. Note that the direction of the lift arm axis Z1 (second direction) is perpendicular to the ascending and descending direction (first direction) of the implement. Lift arm shaft 23 is arranged coaxially with lift arm axis Z1.

5 and 6 show part of the drive system inside the case 1. As shown in FIGS. 4 to 6, the hydraulic cylinder 4 is connected to a hydraulic oil circuit (not shown), and is driven according to supply and discharge of the hydraulic oil. The hydraulic cylinder 4 includes a piston 41 and a piston rod 42 therein. As the hydraulic oil inside the hydraulic cylinder 4 is supplied and discharged, the piston 41 and the piston rod 42 move relative to the case 1 in the front-back direction. In the internal space of the case 1, the rear end side of the piston rod 42 is connected to the rotating tip side of the crank arm 43. Further, the rotation fulcrum side of the crank arm 43 is connected to the center portion of the lift arm shaft 23 in the left-right direction. Thereby, the relative movement of the piston 41 and the piston rod 42 in the longitudinal direction is converted into rotation of the lift arm shaft 23.

As shown in FIG. 4, the hydraulic cylinder 4 is arranged in the internal space of the case 1 so that the axes of the piston 41 and the piston rod 42 are along the front-rear direction and are closer to the front left side. A portion of each

transmission mechanism

20, 30, 40, which will be described later, is accommodated between the hydraulic cylinder 4 and the upper inner wall and right inner wall of the case 1. Further, a hydraulic oil control valve 5 is housed between the hydraulic cylinder 4 and the right inner wall of the case 1.

The control valve 5 has a hydraulic oil flow path formed inside and is interposed in the hydraulic oil circuit. Other components connected to and interposed in the circuit include a hydraulic pump, a relief valve, a flow path switching valve, a safety valve, and a drop adjustment valve. These components are configured as either one with the case 1 or as separate components. The control valve 5 is located to the right of the hydraulic cylinder 4 in the internal space of the case 1. The control valve 5 has a spool 51 in the hydraulic oil flow path. The front end side 51a of the spool 51 is exposed outside the hydraulic oil flow path of the control valve 5. The spool 51 is displaceable in the front-rear direction relative to the housing of the control valve 5. The spool 51 is constantly biased forward by a spring.

The front end side 51a of the spool 51 is pressed rearward by the cams of the

respective transmission mechanisms

20, 30, and 40 against the urging force. At this time, the position of the spool 51 is displaced rearward, and supply of hydraulic oil to the hydraulic cylinder 4 is permitted. As hydraulic oil is supplied to the hydraulic cylinder 4 and the piston 41 and piston rod 42 are displaced, the lift arm 2 rotates relatively through transmission from the crank arm 43 and the lift arm shaft 23. On the other hand, when the pressure by the cam of each

transmission mechanism

20, 30, 40 is released, the position of the spool 51 is displaced forward along the force, and the supply of hydraulic oil to the hydraulic cylinder 4 is regulated. As a result, the displacement of the piston 41 and the piston rod 42 and the rotation of the crank arm 43 and the lift arm shaft 23 are respectively regulated, and the position (height) of the lift arm 2, which has been relatively rotating, is fixed.

As shown in FIGS. 1 and 2, the position control lever 6, the pumper lever 7, and the draft control lever 8 are located on the outside of the case 1, on the right side, and in front of the lift arm 2, respectively. are doing. In the position control lever 6, one end side 61 and the other end side 62 are defined. One end side 61 is configured to be operable by an operator. The other end side 62 is pivotally supported at the right end portion of a first position control shaft 220 that passes through the right side surface from inside the case 1 (see FIGS. 8 and 10). The position control lever 6 projects upward from the other end side 62 toward the one end side 61. When one end 61 of the position control lever 6 is operated by an operator, the position control lever 6 rotates relative to the case 1 about the other end 62 as a fulcrum as a displacement corresponding to the operation. That is, the one end side 61 can swing back and forth using the other end side 62 as a fulcrum.

In the pumper lever 7, one end side 71 and the other end side 72 are defined. One end side 71 is configured to be operable by an operator. Separately, a grip (not shown) that can be held by the operator may be provided. The other end 72 is pivotally supported at the right end of a pump shaft 320 that passes through the right side surface from inside the case 1 (see FIGS. 8 and 11). The pumper lever 7 projects upward from the other end side 72 toward the one end side 71. The other end side 72 of the pumper lever 7 is located above the other end side 62 of the position control lever 6. When one end side 71 is operated by an operator, the pumper lever 7 rotates relative to the case 1 with the other end side 72 as a fulcrum as a displacement according to the operation. That is, the one end side 71 can swing back and forth using the other end side 72 as a fulcrum. More specifically, the pumper lever 7 is moved from a first position, which is an arbitrary position when supply and discharge of hydraulic oil is regulated by the control valve 5, to the first position according to the operator's operation. It is configured to be able to be displaced to a second position different from the first position.

Here, the "state in which the supply and discharge of hydraulic oil is regulated by the control valve 5" means, for example, that the position of the spool 51 is directed toward the side that restricts the supply and discharge of hydraulic oil due to displacement of the position feedback rod 9. This is the state after displacement. Regarding the relationship between the "first position" and the "second position", it is sufficient that the positions of the one end side 71 are different from each other. For example, the one end side 71 at the second position may be located on the front side or the one end side 71 at the first position. By moving the position of the one end side 71, the position of the spool 51 is displaced toward the side where supply and discharge of hydraulic oil is permitted.

The pumper lever 7 has a detent mechanism as a detent for relative rotation. In this embodiment, the detent mechanism functions only on the lowering side of the pumper lever 7, but in addition to this, it may also function on the raising side of the pumper lever 7. In addition to the detent mechanism, the pumper lever 7 includes a rotation regulating portion 74 that regulates relative rotation of the pumper lever 7. The rotation restricting portion 74 may be indirectly fixed to the case 1 via a plate 73 provided on the case 1, for example. The rotation restricting portion 74 includes a protrusion member 74a that protrudes forward. The protruding member 74a is located at the rear of the pumper lever 7, and the front end of the protruding member 74a can intersect with the radial locus of the pumper lever 7. Therefore, if the one end side 71 continues to swing backward, the pumper lever 7, which rotates counterclockwise in FIG. 2, will eventually come into contact with the front end of the protruding member 74a. At this time, the relative rotation of the pumper lever 7 is restricted. As a result of restricting relative rotation, the vertical height of the connected implements can be easily adjusted to any desired position.

Note that the position of the front end of the protruding member 74a can be adjusted in the front-rear direction using a length adjustment mechanism such as a screw. That is, the position where the pumper lever 7 contacts the protrusion member 74a is also adjusted in the front-rear direction. Therefore, the relative rotation of the pumper lever 7 is regulated more toward the front as the position of the front end of the protrusion member 74a is displaced forward.

In the draft control lever 8, one end side 81 and the other end side 82 are defined. One end side 81 is configured to be operable by an operator. The other end side 82 is pivotally supported at the right end portion of a first draft control shaft 420 that passes through the right side surface from inside the case 1 (see FIGS. 8 and 12). The draft control lever 8 projects upward from the other end side 82 toward the one end side 81. The other end side 82 of the draft control lever 8 is located coaxially with the other end side 62 of the position control lever 6. The draft control lever 8 is located to the left of the position control lever 6. When one end side 81 is operated by an operator, the draft control lever 8 rotates relative to the case 1 with the other end side 82 as a fulcrum as a displacement according to the operation. That is, the one end side 81 can swing back and forth using the other end side 82 as a fulcrum.

As shown in FIGS. 3 to 6, the position feedback rod 9 and the draft feedback rod 10 are located on the outside and left side of the case 1, and extend in the front-rear direction. The rear end side 91 of the position feedback rod 9 is connected to the lower end of the cam 24 so as to be relatively rotatable. The cam 24 is coaxially fixed to the lift arm shaft 23 of the left lift arm 2 and protrudes downward. When the lift arm 2 rotates relative to the case 1, the cam 24 also rotates together, and the lower end of the cam 24 swings back and forth. Accordingly, the position feedback rod 9 can be displaced in the front-rear direction.

The front end side 92 of the position feedback rod 9 is connected to the lower end of the cam 230a so as to be relatively rotatable. The cam 230a is pivotally supported at the left end of a second position control shaft 230 that passes through the left side surface from inside the case 1, and protrudes downward (see FIGS. 8 and 10). When the position feedback rod 9 is displaced in the longitudinal direction, the lower end of the cam 230a swings in the longitudinal direction, and the second position control shaft 230 is relatively rotatable.

The rear end side 101 of the draft feedback rod 10 is connected to the lower end of the joint 34. The joint 34 is integrally fixed to the left side plate 35 of the bracket 3 and protrudes downward on the left side. When the bracket 3 rotates relative to the case 1, the joint 34 also rotates together, and the lower end of the joint 34 swings back and forth. Accordingly, the draft feedback rod 10 is movable in the front-rear direction.

The front end side 102 of the draft feedback rod 10 is connected to the lower end of the cam 430a so as to be relatively rotatable. A part of the front end side 102 is constituted by a spring 102a. The cam 430a is pivotally supported at the left end of a second draft control shaft 430 that passes through the left side surface from inside the case 1, and protrudes downward to the left side (see FIGS. 8 and 12). The connection position of the front end side 102 with the cam 430a is higher than the connection position of the front end side 92 of the position feedback rod 9 with the cam 230a. When the draft feedback rod 10 is displaced in the longitudinal direction, the lower end of the cam 430a swings in the longitudinal direction, and the second draft control shaft 430 is relatively rotatable. In particular, when the draft feedback rod 10 is displaced forward, the spring 102a is slightly compressed from its installation length, and the cam 430a swings forward while being biased by the spring 102a. On the other hand, when the draft feedback rod 10 is displaced backward, the spring 102a does not interfere (does not stretch).

<Bracket configuration>
As shown in FIGS. 1, 5, and 6, the bracket 3 is located on the rear side of the other end 22 of the lift arm 2 and at the outer rear end of the case 1. In the bracket 3, one end side 31 and the other end side 32 are defined. One end side 31 is configured to be connectable to a top link (not shown). That is, in this embodiment, the bracket 3 is a so-called top link bracket. The other end 32 is pivotally supported by a bracket shaft 33 connected to the case 1 at both ends. The bracket 3 rotates relative to the case 1 using the other end side 32 as a fulcrum in response to the traction load from the connected top link (namely, the implement).

The bracket 3 includes a bracket axis Z2 that is an axis of relative rotation with respect to the case 1. Bracket axis Z2 is located parallel to lift arm axis Z1. In this embodiment, the direction of the bracket axis Z2 corresponds to the left-right direction, and corresponds to the second direction. Note that the direction of the bracket axis Z2 (second direction) is perpendicular to the ascending and descending direction (first direction) of the implement. The bracket shaft 33 is arranged coaxially with the bracket axis Z2.

The bracket 3 includes a left side plate 35 and a right side plate 36. The left side plate 35 and the right side plate 36 are disposed at the outer rear end of the case 1 on the left side and the right side of the substantially central portion in the left-right direction, respectively. The surfaces of the left side plate 35 and the right side plate 36 face each other in parallel with a predetermined interval. The left side plate 35 and the right side plate 36 each have substantially the same shape, extend rearward from the other end side 32, and further protrude toward the one end side 31 diagonally downwardly rearward.

Further, the bracket 3 includes

attachment parts

35a, 35b, 35c, 36a, 36b, 36c, and a link pin 37. The

attachment parts

35a, 35b, and 35c are circular through holes, and are provided in the left side plate 35. The

attachment parts

36a, 36b, and 36c are circular through holes, and are provided in the right side plate 36. The

attachment parts

35a and 36a are arranged coaxially with the left-right axis Z3. The

attachment parts

35b and 36b are arranged coaxially with the left-right axis Z4. The attachment parts 35c and 36bc are arranged coaxially with the left-right axis Z5. The axes Z3, Z4, and Z5 are each located parallel to the bracket axis Z2.

The link pin 37 can be coaxially engaged with one set selected from the mounting

parts

35a, 36a, the mounting

parts

35b, 36b, and the mounting

parts

35c, 36c. As an example, the link pin 37 is shown engaged with the mounting

parts

35c, 36c. When attaching the top link to the bracket 3, the engagement holes of the top link end are coaxially positioned between the selected set of mounting parts 35a-c, 36a-c, and the link pin 37 engages with the engagement holes of the top link end. This allows the top link to be connected at its end to the bracket 3 via the link pin 37 so that it can rotate relatively to the bracket 3.

The bracket shaft 33 is configured to generate a biasing force during relative rotation according to the traction load of the implement. The bracket shaft 33 has, for example, a torsion bar structure, and is configured to generate an urging force in the opposite rotational direction in response to a rotational load around the bracket axis Z2. More specifically, when the top link is connected by the link pin 37 and the one end side 31 swings rearward in response to a traction load, the bracket 3 rotates relatively around the bracket axis Z2. In this case, the direction of relative rotation is counterclockwise when viewed from the left side (see FIGS. 3 and 7). In response, the bracket shaft 33 generates a biasing force in the clockwise direction when viewed from the left side. On the other hand, when the one end side 31 swings forward in response to the traction load, the bracket 3 also rotates relatively around the bracket axis Z2. In this case, the direction of relative rotation is clockwise when viewed from the left side. In response, the bracket shaft 33 generates a biasing force in a counterclockwise direction when viewed from the left side. In this way, the one end side 31 can swing back and forth while being biased using the other end side 32 as a fulcrum.

As shown in FIG. 7, the bracket shaft 33 is located on the rear side of the lift arm shaft 23. The bracket axis Z2 of the bracket shaft 33 is located below the lift arm axis Z1 of the lift arm shaft 23 by a height H1 in the vertical direction. The

attachment portions

35a, 35b, and 35c are located on the rear side of the bracket shaft 33. The

attachment parts

35a, 35b, and 35c are arranged in parallel on the left side plate 35 in this order from the upper left to the lower right. Note that the positional relationship of the attachment parts 36a to 36c is also the same as that of the attachment parts 35a to 35c. The axis Z3 of the attachment part 35a is located below the bracket axis Z2 by a height H2a in the vertical direction. The axis Z4 of the attachment part 35b is located below the bracket axis Z2 by a height H2b in the vertical direction. The axis Z5 of the attachment portion 35c is located below the bracket axis Z2 by a height H2c in the vertical direction. In the present embodiment, the axes Z1 to Z5 are parallel to each other in the left-right direction, and the heights H1<H2a<H2b<H2c, but the present invention is not limited thereto.

<Configuration of transmission mechanism>
8 to 13, the hydraulic lifting device 100 includes a position control transmission mechanism 20, a pumper transmission mechanism 30, and a draft control transmission mechanism 40. Each

transmission mechanism

20, 30, 40 is configured to transmit the displacement of each

lever

6, 7, 8 and the displacement of each

rod

9, 10 to a spool 51 of the control valve 5. The displacements input to each

transmission mechanism

20, 30, 40 are finally collected in a position control cam 210, a pumper cam 310, and a draft control cam 410, and displace each of the

cams

210, 310, 410, respectively.

FIG. 9 is an enlarged view of the main parts showing the positional relationship between the

cams

210, 310, 410 and the spool 51 inside the case 1. As shown in FIG. 8, the position control cam 210, the pumper cam 310, and the draft control cam 410 each have a substantially "E" shape when viewed from the left side. From the left side to the right side, the draft control cam 410, the position control cam 210, and the pump cam 310 are arranged in this order so as to be overlapped with each other at intervals. Each of the

cams

210, 310, and 410 is provided with a pin that passes through the substantially central portion of each cam in the vertical direction in the left-right direction for positioning. Each of the

cams

210, 310, and 410 can rotate relative to each other using the pin as a support shaft. As the position control cam 210, pumper cam 310, and draft control cam 410 are displaced, their respective upper end sides 212, 312, 412 or

lower end sides

213, 313, 413 can swing in the front-rear direction.

According to the rocking, the

respective protrusions

211, 311, and 411 can also rock integrally in the front-rear direction. When the

protrusions

211, 311, 411 swing and displace rearward, the front end side 51a of the spool 51 is pressed by the

protrusions

211, 311, 411 and is displaced rearward. Next, when the protruding

portions

211, 311, and 411 are swung and displaced toward the front, the spool 51 is displaced toward the front according to the biasing force of the spring. In this way, the spool 51 of the control valve 5 is also displaced in accordance with the displacement of each

cam

210, 310, 410. The specific operation of each

cam

210, 310, 410 will be explained when the details of each

transmission mechanism

20, 30, 40 are explained.

Hereinafter, the respective configurations of the position control transmission mechanism 20, the pump transmission mechanism 30, and the draft control transmission mechanism 40 will be described in detail.

<<Position control transmission mechanism>>
FIG. 10 is an overall view of the position control transmission mechanism 20. As shown in FIG. 10, the position control transmission mechanism 20 includes a position control cam 210, a first position control shaft 220, and a second position control shaft 230.

The first position control shaft 220 includes a co-rotating shaft 221, a reverse-rotating shaft 222, and a rotation transmitting section 223. The co-rotating shaft 221 extends in the left-right direction and has an axis A1 parallel to the left-right direction. The same direction rotating shaft 221 is connected to the other end 62 of the position control lever 6 at its right end. The same direction rotating shaft 221 is rotatable around the axis A1 in the same direction as the rotation direction of the position control lever 6. A cam 221a that projects upward is provided on the left end side of the co-rotating shaft 221. The cam 221a can swing back and forth in accordance with the rotation of the co-rotating shaft 221 about the axis A1.

The reverse rotation shaft 222 extends in the left-right direction and has an axis A2 that is parallel to the left-right direction. The axis A2 is located diagonally above and forward of the axis A1. That is, the same-direction rotation shaft 221 and the reverse-direction rotation shaft 222 are arranged to have different axes. As shown in the dashed line portion of FIG. 10 and in FIG. 13, the reverse rotation shaft 222 has a hollow structure along the axis A2, and the reverse rotation shaft 422 of the first draft control shaft 420 can be coaxially inserted inside it.

A cam 222a that protrudes downward is provided on the right end side of the reverse rotation shaft 222. In response to the back-and-forth rocking of the cam 222a, the reverse rotation shaft 222 can rotate around the axis A2 in a direction opposite to the rotation direction of the position control lever 6. A cam 222b that protrudes downward is provided on the left end side of the reverse rotation shaft 222. The cam 222b can swing back and forth in response to the rotation of the reverse rotation shaft 222 about the axis A2.

The rotation transmission section 223 is a plate that extends in the front-rear direction. The rear side of the rotation transmission section 223 is rotatably connected to the upper end of the cam 221a, and the front side of the rotation transmission section 223 is rotatably connected to the lower end of the cam 222a. The rotation transmission section 223 is configured to swing the cam 222a in the front-back direction in response to the swing of the cam 221a in the front-back direction.

In the first position control shaft 220 configured in this way, when the position control lever 6 is operated, the same direction rotation shaft 221 rotates around the axis A1 and rotates in the opposite direction according to the displacement of the position control lever 6. Shaft 222 rotates around axis A2. More specifically, when the position control lever 6 and the co-rotating shaft 221 rotate in the direction R1 by operating the position control lever 6, the cam 221a swings forward. Direction R1 corresponds to the clockwise direction when viewed from right to left. As the cam 221a swings forward, the cam 222a also swings forward via the rotation transmission section 223. In response to the forward rocking of the cam 222a, the reverse rotation shaft 222 rotates in a direction R2 opposite to the direction R1. Direction R2 corresponds to a counterclockwise direction when viewed from right to left.

On the other hand, when the position control lever 6 and the co-rotating shaft 221 rotate in the direction R2 due to the operation of the position control lever 6, the cam 221a swings rearward. As the cam 221a swings rearward, the cam 222a also swings rearward via the rotation transmission section 223. In response to the rearward rocking of the cam 222a, the reverse rotation shaft 222 rotates in the direction R1 opposite to the direction R2. That is, the rotation transmitting unit 223 transmits the rotation of the same-direction rotating shaft 221 to the opposite-direction rotating shaft 222, and rotates the opposite-direction rotating shaft 222 in a direction opposite to the rotation direction of the same-direction rotating shaft 221. It looks like this.

The second position control shaft 230 extends in the left-right direction and has an axis A3 that is parallel to the left-right direction. The axis A3 is located above the axis A2. In other words, the first position control shaft 220 and the second position control shaft 230 are arranged to have different axes, and the second position control shaft 230 is located above the first position control shaft 220.

A cam 230a that protrudes downward is provided on the left end side of the second position control shaft 230. A front end side 92 of the position feedback rod 9 is connected to the lower end of the cam 230a so as to be relatively rotatable. The second position control shaft 230 is rotatable around the axis A3 in response to the back-and-forth rocking of the cam 230a.

A cam 230b that protrudes upward is provided slightly to the right of the center of the second position control shaft 230 in the left-right direction. The cam 230b can swing back and forth in response to the rotation of the second position control shaft 230 about the axis A3. On the right end side of the second position control shaft 230, an extension portion 231 having the same diameter is provided. The extension portion 231 extends to the right from the cam 230b coaxially with the axis A3.

The second position control shaft 230 configured in this manner rotates around axis A3 in response to the displacement of the position feedback rod 9 when the lift arm 2 rotates relative to the lift arm 2. More specifically, when the cam 24 swings rearward due to the lift arm 2 swinging upward, the position feedback rod 9 is displaced rearward. In response to the rearward displacement of the position feedback rod 9, the cam 230a swings rearward. In response to the rearward swing of the cam 230a, the second position control shaft 230 rotates in direction R1.

On the other hand, when the cam 24 swings forward due to the downward swing of the lift arm 2, the position feedback rod 9 is displaced forward. In response to the forward displacement of the position feedback rod 9, the cam 230a swings forward. In response to the forward rocking of the cam 230a, the second position control shaft 230 rotates in a direction R2 opposite to the direction R1.

In the position control cam 210, a protrusion 211, an upper end side 212, and a lower end side 213 are defined. The protruding portion 211 protrudes rearward from the substantially central portion in the vertical direction, and can come into contact with the front end side 51a of the spool 51 as described above. The upper end side 212 is connected to a cam 230b of the second position control shaft 230 so as to be relatively rotatable. The lower end side 213 is connected to a cam 222b of a reverse rotation shaft 222 (first position control shaft 220) so as to be relatively rotatable.

By operating the position control lever 6, the position control lever 6 and the same-direction rotating shaft 221 rotate in the direction R2, and when the opposite-direction rotating shaft 222 rotates in the direction R1, the cam 222b swings rearward. In response to the rearward swinging of the cam 222b, the lower end side 213 of the position control cam 210 also swings rearward, and the protrusion 211 is also displaced rearward. As a result, the spool 51 is displaced toward the side (ie, the rear side) that allows supply and discharge of hydraulic oil. The displacement of the spool 51 causes the lift arm 2 to swing upward.

Next, as the lift arm 2 swings upward, the second position control shaft 230 rotates in the direction R1, and the cam 230b swings forward. In response to the forward swinging of the cam 230b, the upper end side 212 of the position control cam 210 also swings forward, and the protrusion 211 is also displaced forward. As a result, the spool 51 is displaced toward the side where supply and discharge of hydraulic oil is restricted (ie, the front side). The displacement of the spool 51 causes the lift arm 2 swinging upward to stop.

<<Pumper transmission mechanism>>
11 is an overall view of the pump transmission mechanism 30. As shown in FIG. 11, the pump transmission mechanism 30 includes a pump cam 310, a pump shaft 320, and a rotation transmission portion 330.

The pumper shaft 320 extends in the left-right direction and is arranged coaxially with the axis A3. As shown in the broken line in FIG. 11 and in FIG. 13, the pumper shaft 320 has a hollow structure along the axis A3, into which the extension part 231 of the second position control shaft 230 can be coaxially fitted. It has become.

The pumper shaft 320 is connected to the other end 72 of the pumper lever 7 at its right end. The pumper shaft 320 is rotatable around the axis A3 in the same direction as the rotational direction of the pumper lever 7. A cam 320a that projects downward is provided on the left end side of the pumper shaft 320. The cam 320a can swing back and forth in accordance with the rotation of the pump shaft 320 about the axis A3.

The rotation transmission section 330 is a plate that extends in the vertical direction, and is arranged coaxially with the axis A2. As shown in the broken line part in FIG. 11 and in FIG. It is possible to insert it. The upper side of the rotation transmitting section 330 is rotatably connected to the lower end of the cam 320a, and the lower side of the rotation transmitting section 330 is rotatably connected to the lower end side 313 of the pump cam 310. The rotation transmission section 330 is configured to swing the lower end side 313 in the front-back direction in response to the swing of the cam 320a in the front-back direction.

The pumper shaft 320 configured in this manner rotates around the axis A3 in accordance with the displacement of the pumper lever 7 when the pumper lever 7 is operated. More specifically, when the pumper shaft 320 rotates in the direction R1 by operating the pumper lever 7, the cam 320a swings rearward. In response to the rearward rocking of the cam 320a, the rotation transmitting section 330 rotates in a direction R2 opposite to the direction R1.

On the other hand, when the pumper lever 7 and the pumper shaft 320 are rotated in the direction R2 by operating the pumper lever 7, the cam 320a swings forward. In response to the frontward swinging of the cam 320a, the rotation transmitting section 330 rotates in the direction R1 opposite to the direction R2.

In the pump cam 310, a protrusion 311, an upper end side 312, and a lower end side 313 are defined. The protruding portion 311 protrudes rearward from the substantially central portion in the vertical direction, and can come into contact with the front end side 51a of the spool 51 as described above. The upper end side 312 is connected to the cam 230b of the second position control shaft 230 so as to be relatively rotatable. More specifically, as shown in FIG. 13, the upper end side 312 is interposed between the cam 230b and the upper end side 212 of the position control cam 210. The cam 230b and the upper end sides 312, 212 are pinned together so that the upper end sides 312, 212 can swing together in response to the swing of the cam 230b. The lower end side 313 is connected to the lower side of the rotation transmission section 330 so as to be relatively rotatable.

It is assumed that the pumper lever 7, which is in the first position, is moved to the second position in a state where the supply and discharge of hydraulic oil is regulated by the control valve 5. When the pumper lever 7 and the pumper shaft 320 rotate in the direction R2 by operating the pumper lever 7, the cam 320a swings forward, and the rotation transmitting section 330 rotates in the direction R1. In accordance with the rotation of the rotation transmission section 330 in the direction R1, the lower end side 313 of the pump cam 310 also swings rearward, and the protrusion 211 is also displaced rearward. As a result, the spool 51 is displaced toward the side (ie, the rear side) that allows supply and discharge of hydraulic oil. According to the displacement of the spool 51, the lift arm 2 swings upward.

Next, as the lift arm 2 swings upward, the second position control shaft 230 rotates in the direction R1, and the cam 230b swings forward. As the cam 230b swings forward, the upper end 212 of the position control cam 210 as well as the upper end 312 of the pump cam 310 swings forward, and the protrusion 311 also moves forward. As a result, the spool 51 is displaced toward the side where supply and discharge of hydraulic oil is restricted (ie, the front side). In response to the displacement of the spool 51, the lift arm 2, which had been swinging upward, stops.

<<Draft control transmission mechanism>>
FIG. 12 is an overall view of the draft control transmission mechanism 40. As shown in FIG. 12, the draft control transmission mechanism 40 includes a draft control cam 410, a first draft control shaft 420, and a second draft control shaft 430.

The first draft control shaft 420 includes a co-rotating shaft 421, a reverse-rotating shaft 422, and a rotation transmitting section 423. The co-rotating shaft 421 extends in the left-right direction and is disposed coaxially with the axis A1. As shown in the broken line part in FIG. 11 and in FIG. 12, the co-rotating shaft 421 has a hollow structure along the axis A1, and the co-rotating shaft 221 of the first position control shaft 220 is coaxially inserted therein. It can be inserted into. The co-rotating shaft 421 is connected to the other end 82 of the draft control lever 8 at its right end. The same direction rotating shaft 421 is rotatable around the axis A1 in the same direction as the rotation direction of the draft control lever 8. A cam 421a that protrudes upward is provided on the left end side of the co-rotating shaft 421 so as to be adjacent to the right side of the cam 221a. The cam 421a can swing back and forth in accordance with the rotation of the co-rotating shaft 421 about the axis A1. Note that each swinging

cam

421a, 221a can come into contact with the stay. When in contact with the stay, the swinging of each

cam

421a, 221a is restricted, and the operation of each

lever

6, 8 is also restricted. That is, by adjusting the contact position between each

cam

421a, 221a and the stay, the operating range of each

lever

6, 8 can be set. For example, in this embodiment, the operating range may be set so that the operating angle of each

lever

6, 8 is 45 degrees.

The reverse rotation shaft 422 extends in the left-right direction and is arranged coaxially with the axis A2. That is, the same direction rotating shaft 421 and the opposite direction rotating shaft 422 are arranged to have different axes. As shown in the broken line in FIG. 11 and in FIG. 12, the reverse rotation shaft 422 is fitted inside the reverse rotation shaft 222 of the first position control shaft 220.

A cam 422a that protrudes downward is provided on the right end side of the reverse rotation shaft 422 so as to be adjacent to the right side of the cam 222a. In response to the back and forth rocking of the cam 422a, the reverse rotation shaft 422 can rotate around the axis A2 in a direction opposite to the rotation direction of the draft control lever 8. A cam 422b that protrudes downward is provided on the left end side of the reverse rotation shaft 422. The cam 422b can swing back and forth in response to the rotation of the reverse rotation shaft 422 about the axis A2.

The rotation transmission section 423 is a plate adjacent to the right side of the rotation transmission section 223 and extending in the front-rear direction. The rear side of the rotation transmission section 423 is rotatably connected to the upper end of the cam 421a, and the front side of the rotation transmission section 423 is rotatably connected to the lower end of the cam 422a. The rotation transmission section 423 is configured to swing the cam 422a in the front-back direction in response to the swing of the cam 421a in the front-back direction.

In the first draft control shaft 420 configured in this way, when the draft control lever 8 is operated, the same direction rotating shaft 421 rotates around the axis A1 and rotates in the opposite direction according to the displacement of the draft control lever 8. Shaft 422 rotates around axis A2. More specifically, when the draft control lever 8 and the co-rotating shaft 421 rotate in the direction R1 by operating the draft control lever 8, the cam 421a swings forward. In response to the forward swinging of the cam 421a, the cam 422a also swings forward via the rotation transmission section 423. In response to the forward rocking of the cam 422a, the reverse rotation shaft 422 rotates in a direction R2 opposite to the direction R1.

On the other hand, when the draft control lever 8 and the co-rotating shaft 421 rotate in the direction R2 due to the operation of the draft control lever 8, the cam 421a swings rearward. As the cam 421a swings rearward, the cam 422a also swings rearward via the rotation transmission section 423. In response to the rearward rocking of the cam 422a, the reverse rotation shaft 422 rotates in the direction R1 opposite to the direction R2. That is, the rotation transmitting unit 423 transmits the rotation of the same-direction rotating shaft 421 to the opposite-direction rotating shaft 422, and rotates the opposite-direction rotating shaft 422 in a direction opposite to the rotation direction of the same-direction rotating shaft 421. It looks like this.

The second draft control shaft 430 extends in the left-right direction and is arranged coaxially with the axis A3. As shown in the dashed line in FIG. 12 and in FIG. 13, the second draft control shaft 430 has a hollow structure along the axis A3, into which the second position control shaft 230 can be coaxially fitted. ing. That is, the first draft control shaft 420 and the second draft control shaft 430 are arranged to have mutually different axes, and the second draft control shaft 430 is located above the first draft control shaft 420. ing.

A cam 430a that protrudes downward is provided on the left end side of the second draft control shaft 430. The front end side 102 of the draft feedback rod 10 is connected to the lower end of the cam 430a so as to be relatively rotatable. The second draft control shaft 430 is rotatable around the axis A3 in response to the back-and-forth rocking of the cam 430a.

A cam 430b that protrudes upward is provided on the right end side of the second draft control shaft 430. The cam 430b can swing back and forth in response to the rotation of the second draft control shaft 430 about the axis A3.

The second draft control shaft 430 configured in this manner rotates around the axis A3 in accordance with the displacement of the draft feedback rod 10 when the bracket 3 rotates relative to the other. More specifically, when the joint 34 swings rearward due to rearward rocking of the bracket 3, the draft feedback rod 10 is displaced rearward without the spring 102a extending from its attachment length. In response to the rearward displacement of the draft feedback rod 10, the cam 430a swings rearward. In response to the rearward rocking of the cam 430a, the second draft control shaft 430 rotates in the direction R1.

On the other hand, when the joint 34 swings forward due to the forward swing of the bracket 3, the draft feedback rod 10 is displaced forward. In this case, the draft feedback rod 10 is displaced while the spring 102a is slightly shortened from the mounting length. In this way, the spring 102a shortens, thereby suppressing hunting due to input. For example, the spring constant of the spring 102a may be adjusted so that the hunting can be appropriately suppressed. In response to the forward displacement of the draft feedback rod 10, the cam 430a swings forward. In response to the forward swing of the cam 430a, the second draft control shaft 430 rotates in a direction R2 opposite to the direction R1.

As shown in FIGS. 12 and 13, a protrusion 102b is further provided on the front end side 102 of the draft feedback rod 10. The protrusion 102b protrudes to the right and is located above the position feedback rod 9 and behind the cam 230a of the second position control shaft 230. That is, the protruding portion 102b can intersect with the radial locus of the cam 230a.

Therefore, for example, when the position feedback rod 9 continues to be displaced backward, the cam 230a, which is relatively rotating backward, will eventually come into contact with the protrusion 102b. After the contact, when the position feedback rod 9 is further displaced rearward, the cam 230a presses the protrusion 102b rearward, causing the spring 102a to contract. As a result, the portion of the draft feedback rod 10 rearward of the spring 102a is not displaced rearward, and the bracket 3 does not swing. On the other hand, in conjunction with the protrusion 102b being pushed rearward, the cam 430a also swings rearward, and the second draft control shaft 430 rotates in the direction R1.

In the draft control cam 410, a protrusion 411, an upper end side 412, and a lower end side 413 are defined. The protruding portion 411 protrudes rearward from the substantially central portion in the vertical direction, and can come into contact with the front end side 51a of the spool 51, as described above. The upper end side 412 is connected to a cam 430b of the second draft control shaft 430 so as to be relatively rotatable. The lower end side 413 is connected to a cam 422b of a reverse rotation shaft 422 (first draft control shaft 420) so as to be relatively rotatable.

Hereinafter, the operations associated with the operation of the draft control lever 8 will be explained. The premise of operation is that a traction load from the top link (implement) is applied to the bracket 3, the bracket 3 is oscillated according to the traction load, and the spool 51 is positioned in a neutral state. It is assumed that there is In this state, when the draft control lever 8 and the same direction rotating shaft 421 are rotated in the direction R2 by operating the draft control lever 8, and the opposite direction rotating shaft 422 is rotated in the direction R1, the cam 422b is moved to the rear side. oscillate. In response to the rearward swinging of the cam 422b, the lower end side 413 of the draft control cam 410 also swings rearward, and the protrusion 411 is also displaced rearward. As a result, the spool 51 is displaced toward the side (ie, the rear side) that allows supply and discharge of hydraulic oil. The displacement of the spool 51 causes the lift arm 2 to swing upward.

Next, as the lift arm 2 swings upward, the implement connected to the lift arm 2 is also displaced upward. For example, if the lower end of the implement is intruding into the ground, the degree of plowing depth will be reduced. Further, when the lower end of the implement is separated from the ground, the separation distance increases. Therefore, the traction load from the top link to the bracket 3 changes, and the bracket 3 rotates relative to it accordingly. Due to the relative rotation of the bracket 3, the second draft control shaft 430 rotates in the direction R1, and the cam 430b swings forward.

On the other hand, when the cam 230a presses the protrusion 102b rearward due to upward swinging of the lift arm 2, the spring 102a of the draft feedback rod 10 contracts. On the other hand, the cam 430a also swings rearward in conjunction with the protrusion 102b being pushed rearward. Also in this case, the second draft control shaft 430 rotates in the direction R1, and the cam 430b swings forward.

In response to the forward swinging of the cam 430b, the upper end side 412 of the draft control cam 410 also swings forward, and the protrusion 411 is also displaced forward. As a result, the spool 51 is displaced toward the side where supply and discharge of hydraulic oil is restricted (ie, the front side). The displacement of the spool 51 causes the lift arm 2, which swings upward, to stop.

<Effects of embodiment>
As described above, the hydraulic lifting device 100 according to the first embodiment of the present invention includes the lift arm 2, the bracket 3, the draft control lever 8, and the draft control transmission mechanism 40. This allows draft control to be executed. The lift arm 2 rotates relative to the case 1 using the other end 22 as a fulcrum in order to raise and lower the connected implement. The bracket 3 is provided at the rear end of the case 1, and rotates relative to the case 1 using the other end side 32 as a fulcrum in response to a traction load from a connected top link (namely, an implement). Further, the bracket 3 includes

attachment portions

35a, 35b, 35c, 36a, 36b, and 36c configured to allow attachment of the front end of the top link. Here, the lift arm 2 includes a lift arm axis Z1 that is an axis of relative rotation with respect to the case 1. The bracket 3 includes a bracket axis Z2 that is an axis of relative rotation with respect to the case 1, and further includes axes Z3, Z4, and Z5 of the mounting portions 35a to 35c, and 36a to c. The lift arm axis Z1, the bracket axis Z2, and the respective axes Z3, Z4, and Z5 are arranged in a direction (second direction, in this embodiment) perpendicular to the up-and-down direction (first direction, in this embodiment, the vertical direction) of the implement. They extend in the left-right direction) and are parallel to each other. In the first direction, the bracket axis Z2 is located below the lift arm axis Z1, and the mounting parts 35a to 35c, 36a to 36a have the respective axes Z3, Z4, and Z5 below the bracket axis Z2. c is located (see Figure 7).

By connecting the front end of the top link to the attachment portions 35a to 36a to 36c configured in this manner, the front end of the top link can be positioned sufficiently downward. Therefore, the distance between the connected implement and the ground can be easily increased. In particular, compared to a configuration in which the mounting portions 35a to 36a to 36c are located above the bracket axis Z2, the front end of the top link can be located further downward, and the above-mentioned separation distance can be made larger. can. For example, even if a work machine to which the hydraulic lifting device 100 of the first embodiment is applied is tilted with respect to the ground when traveling on uneven ground, uneven ground, slope, etc., the distance between the implement and the ground can be reduced. Since it can be made larger, contact between the implement and the ground can be suppressed. More specifically, when the tractor equipped with the hydraulic lifting device 100 of this embodiment goes over a ridge, the ridge can be prevented from collapsing without bringing the implement into contact with the ground.

Furthermore, in the first embodiment, a bracket shaft 33 is particularly provided. The bracket shaft 33 pivotally supports the other end side 32 of the bracket 3 on the outer rear end of the case 1, and is arranged coaxially with the bracket axis Z2. The bracket shaft 33 is configured to generate an urging force during relative rotation according to the traction load. According to this, the bracket shaft 33 can be provided with a biasing function required for executing draft control. That is, the bracket shaft 33 serves both as a support shaft for the bracket 3 and as a biasing mechanism, and there is no need to add a separate biasing mechanism. Therefore, it is no longer necessary to interpose a biasing mechanism between the one end side 31 of the bracket 3 and the case 1, for example, as in the conventional case. Therefore, it is possible to increase the room for positioning the bracket shaft Z2 or the attachment portions 35a to 35c, 36a to 36c further downward.

In the first embodiment, the draft control transmission mechanism 40 includes a draft control cam 410, a first draft control shaft 420, and a second draft control shaft 430. When the draft control lever 8 is operated, the first draft control shaft 420 rotates around the axis A1 (and axis A2) in response to the displacement of the draft control lever 8. When the bracket 3 rotates relative to the draft control lever 8, the second draft control shaft 430 rotates around the axis A3 in response to the displacement of the draft feedback rod 10. When the first draft control shaft 420 rotates, the draft control cam 410 displaces the position of the spool 51 toward the allowable side of the supply and discharge of the hydraulic oil in response to the rotation of the first draft control shaft 420. When the second draft control shaft 430 rotates, the draft control cam 410 displaces the position of the spool 51 toward the restrictive side of the supply and discharge of the hydraulic oil in response to the rotation of the second draft control shaft 430. This makes it easy to adjust the lift height of the lift arm 2 so that the traction load on the bracket 5 is the desired magnitude.

The second draft control shaft 430 is located above the first draft control shaft 420 in the vertical direction of the top link (implement). In this embodiment, the axis A3 of the second draft control shaft 430 is located above the axis A1 of the first draft control shaft 420. According to this, the lower side of the second draft control shaft 430 can be effectively used as a space for accommodating components. For this reason, for example, as shown in FIG. 8, the hydraulic cylinder 4 is housed below the second draft control shaft 430 and on the left side of the first draft control shaft 420, so that the hydraulic lifting device 100 can be operated. The overall size can be made smaller. In this way, the degree of freedom in layout of component parts can be increased.

Therefore, the lifting height of the lift arm 2 can be easily adjusted so that the traction load on the bracket 5 reaches a target level, and the degree of freedom in the layout of the component parts can be increased. Moreover, the hydraulic cylinder 4, which is heavy among the components, can be arranged below in the internal space of the hydraulic lifting device 100. Therefore, the position of the center of gravity of the hydraulic lifting device 100 can be adjusted over a wide range.

For example, in the first embodiment, the draft control lever 8 is defined by one end side 81 and the other end side 82, and the one end side 81 is configured to be operable by the operator, and the other end side is configured to be able to be operated by the operator. It is configured to be rotatable relative to the case 1 about the side 82 as a fulcrum. The first draft control shaft 420 includes a co-rotating shaft 421 , a reverse-rotating shaft 422 , and a rotation transmitting section 423 . The same direction rotation shaft 421 is connected to the other end side 82 of the draft control lever 8 and is configured to be rotatable in the same direction as the rotation direction of the draft control lever 8. The reverse rotation shaft 422 is connected to the draft control cam 410 and is configured to be rotatable in a direction opposite to the rotation direction of the draft control lever 8. The rotation transmitter 423 transmits the rotation of the same-direction rotating shaft 421 to the opposite-direction rotating shaft 422 when the draft control lever 8 rotates relative to the draft control lever 8 , and also transmits the rotation of the same-direction rotating shaft 421 to the opposite-direction rotating shaft 421 . Rotate in the opposite direction.

According to this, the same direction rotation shaft 421 and the opposite direction rotation shaft 422 can be arranged with different axes via the rotation transmission part 423. For example, as shown in FIG. 12, the position of the axis A1 of the same direction rotating shaft 421 and the position of the axis A2 of the opposite direction rotating shaft 422 can be made different from each other. Therefore, the same direction rotating shaft 421 and the opposite direction rotating shaft 422 can be laid out without interfering with the arrangement of the hydraulic cylinder 4, control valve 5, etc. That is, the degree of freedom in the layout of the first draft control shaft 420 and the draft control lever 8 can be increased, and for example, a layout that is easy for the operator to operate can be adopted. Furthermore, by changing the link ratio in the rotation transmission section 423, the amount of displacement of the draft control cam 410 (the amount of displacement of the spool 51) relative to the amount of displacement of the draft control lever 8 can be adjusted. Therefore, the operating range of the draft control lever 8 can be adjusted so that the operator can easily operate the draft control lever 8.

In addition, in the first embodiment, a position control lever 6 and a position control transmission mechanism 20 are particularly provided. The position control transmission mechanism 20 includes a position control cam 210, a first position control shaft 220, and a second position control shaft 230. The first position control shaft 220 rotates around the axis A1 (and axis A2) according to the displacement of the position control lever 6 when the position control lever 6 is operated. The second position control shaft 230 rotates around the axis A3 according to the displacement of the position feedback rod 9 when the lift arm 2 rotates relative to the other. When the first position control shaft 220 rotates, the position control cam 210 displaces the position of the spool 51 toward the side where supply and discharge of hydraulic oil is permitted according to the rotation of the first position control shaft 220. When the second position control shaft 230 rotates, the position control cam 210 displaces the position of the spool 51 in accordance with the rotation of the second position control shaft 230 toward the side where supply and discharge of hydraulic oil is restricted. Therefore, the height of the lift arm 2 in the vertical direction can be easily adjusted to a target height.

The second position control shaft 230 is located above the first position control shaft 220 in the vertical direction of the top link (implement). In this embodiment, the axis A3 of the second position control shaft 230 is located above the axis A1 of the first position control shaft 220. According to this, the lower side of the second position control shaft 230 can be effectively used as a space for accommodating components. For this reason, for example, as shown in FIG. 8, the hydraulic cylinder 4 is housed below the second position control shaft 230 and on the left side of the first position control shaft 220, so that the hydraulic lifting device 100 can be operated. The overall size can be made smaller. In this way, the degree of freedom in layout of component parts can be increased.

Therefore, the height of the lift arm 2 in the vertical direction can be easily adjusted to the desired height, and the degree of freedom in the layout of the component parts can be increased. Moreover, the hydraulic cylinder 4, which is heavy among the components, can be arranged below in the internal space of the hydraulic lifting device 100. Therefore, the position of the center of gravity of the hydraulic lifting device 100 can be adjusted over a wide range.

Further, in the first embodiment, in particular, the position control lever 6 has one end side 61 and the other end side 62, and the one end side 61 is configured to be operable by the operator, and the other end side 61 is configured to be operable by the operator. It is configured to be rotatable relative to the case 1 using the end side 62 as a fulcrum. The first position control shaft 220 includes a co-rotating shaft 221 , a reverse-rotating shaft 222 , and a rotation transmitting section 223 . The same direction rotation shaft 221 is connected to the other end side 62 of the position control lever 6 and is configured to be rotatable in the same direction as the rotation direction of the position control lever 6. The reverse rotation shaft 222 is connected to the position control cam 210 and configured to be rotatable in a direction opposite to the rotation direction of the position control lever 6. The rotation transmitting unit 223 transmits the rotation of the same-direction rotating shaft 221 to the opposite-direction rotating shaft 222 when the position control lever 6 rotates relative to the position control lever 6 , and also transmits the rotation of the same-direction rotating shaft 221 to the opposite-direction rotating shaft 221 . Rotate in the opposite direction.

According to this, the same direction rotation shaft 221 and the opposite direction rotation shaft 222 can be arranged with different axes via the rotation transmission part 223. For example, as shown in FIG. 10, the position of the axis A1 of the same direction rotating shaft 221 and the position of the axis A2 of the opposite direction rotating shaft 222 can be made different from each other. Therefore, the same direction rotating shaft 221 and the opposite direction rotating shaft 222 can be laid out without interfering with the arrangement of the hydraulic cylinder 4, control valve 5, etc. That is, the degree of freedom in the layout of the first position control shaft 220 and the position control lever 6 can be increased, and for example, a layout that is easy for the operator to operate can be adopted. Furthermore, by changing the link ratio in the rotation transmission section 223, the amount of displacement of the position control cam 210 (the amount of displacement of the spool 51) relative to the amount of displacement of the position control lever 6 can be adjusted. Therefore, the operating range of the position control lever 6 can be adjusted to make it easier for the operator to operate.

Further, in the first embodiment, particularly, one of the first draft control shaft 420 and the first position control shaft 220 has a hollow structure, so that the other can be coaxially fitted into the inside of one. configured. Either the second draft control shaft 430 or the second position control shaft 230 has a hollow structure, and is configured such that the other can be coaxially fitted into the inside of one.

More specifically, as shown in FIGS. 10, 12, and 13, the same direction rotating shaft 221 of the first position control shaft 220 is coaxial with the same direction rotating shaft 421 of the first draft control shaft 420. It will be inserted. The reverse rotation shaft 422 of the first draft control shaft 420 is coaxially fitted into the reverse rotation shaft 222 of the first position control shaft 220 . The second position control shaft 230 is coaxially fitted into the second draft control shaft 430 . Depending on the displacement of either the position control lever 6 or the draft control lever 8, the first position control shaft 220 and the first draft control shaft 420 rotate relative to each other around the axes A1 and A2. Depending on the displacement of either the position feedback rod 9 or the draft feedback rod 10, the second position control shaft 230 and the second draft control shaft 430 rotate relative to each other around the axis A3. According to this, the other shaft can be accommodated inside one shaft, and a space can be secured by the amount of space accommodated in the shaft. Therefore, the degree of freedom in layout of component parts can be further increased.

Furthermore, in the first embodiment, a pumper lever 7 and a pumper transmission mechanism 30 are particularly provided. The pumper lever 7 is configured to be movable from a first position to a second position in response to an operation by an operator. The pump transmission mechanism 30 includes a pump cam 310, a pump shaft 320, and a second position control shaft 230. The pumper shaft 320 rotates around the axis A3 in accordance with the displacement of the pumper lever 7 when the pumper lever 7 is operated and displaced from the first position to the second position. The pump cam 310 displaces the position of the spool 51 toward a side that allows supply and discharge of hydraulic oil in accordance with the rotation of the pump shaft 7 when the pump shaft 7 rotates, and when the second position control shaft 230 rotates. In response to the rotation of the second position control shaft 230, the position of the spool 51 is displaced toward the side where supply and discharge of hydraulic oil is restricted. Therefore, the lift arm 2 can be easily raised and lowered according to the operator's request.

For example, when the pump transmission mechanism 30 is provided with the rotation transmission section 330 as in the first embodiment, the pump shaft 320 and the lower end side 313 of the pump cam 310 can be arranged with different axes via the rotation transmission section 330. (See Figure 11). Therefore, the pump shaft 320 can be laid out without interfering with the arrangement of the hydraulic cylinder 4, control valve 5, etc. That is, the degree of freedom in the layout of the pumper shaft 320 and the pumper lever 7 can be increased, and for example, a layout that is easy for the operator to operate can be adopted. Furthermore, by changing the link ratio in the rotation transmission section 330, the amount of displacement of the pumper cam 310 (the amount of displacement of the spool 51) relative to the amount of displacement of the pumper lever 7 can be adjusted. Therefore, the operating range of the pumper lever 7 can be adjusted to make it easier for the operator to operate.

Further, in the first embodiment, in particular, the pumper lever 7 has one end side 71 and the other end side 72, and the one end side 71 is configured to be operable by the operator, and the other end side is configured to be able to be operated by the operator. It is configured to be rotatable relative to the case 1 using the side 72 as a fulcrum. Further, a rotation regulating portion 74 for regulating relative rotation of the pumper lever 7 is provided. Thereby, the height at which the implement is raised by operating the pumper lever 7 can be intentionally regulated so as to be at an arbitrary position. For example, if the instrument is raised too high, the center of gravity also rises, increasing the risk of falling. In particular, when using a relatively heavy implement (for example, a plow, etc.) on a slope, the risk of overturning often increases. In such a case, the height of the implement can be appropriately regulated and safety can be improved. On the other hand, by regulating the height at which the implement can be raised to the minimum necessary height, for example, when lowering the implement after turning during work interruption, the implement will not touch the ground. You can shorten the time it takes. Therefore, the time required for work interruption can be shortened, and work efficiency can be improved accordingly.

[Second embodiment]
Next, a second embodiment of the present invention will be described. The hydraulic lifting device 100 according to the second embodiment of the present invention differs from the above-described first embodiment in the following points. In the hydraulic lifting device 100 of the second embodiment, the configuration of the bracket 3 is different from that of the first embodiment. Further, in order to interlock the second draft control shaft 430 with the rotation of the second position control shaft 230, a predetermined mechanism is added near the front end of each

feedback rod

9, 10 in the first embodiment. It is different from the form. The second embodiment is the same as the first embodiment except for these points. Hereinafter, only the differences between the second embodiment and the first embodiment will be described. In addition, in the constituent parts of the second embodiment, the same or equivalent parts as those of the first embodiment are given the same reference numerals, and the description thereof will be omitted.

FIG. 14 is a left side view of the hydraulic lifting device 100 of the second embodiment, and corresponds to FIG. 3. FIG. 15 is a diagram showing the positional relationship of each axis in the hydraulic lifting device 100 of the second embodiment, and corresponds to FIG. 7. As shown in FIGS. 14 and 15, the left side plate 35 and the right side plate 36 of the bracket 3 have substantially the same shape, extend from the other end side 32 to the rear side, and further extend from the lower one end side. It protrudes towards 31. The

attachment parts

35a, 35b, and 35c are arranged in this order vertically downward from above on the left side plate 35. Note that the positional relationship of the attachment parts 36a to 36c is also the same as that of the attachment parts 35a to 35c.

As shown in FIG. 15, the bracket axis Z2 of the bracket shaft 33 is located above the lift arm axis Z1 of the lift arm shaft 23 by a height H3 in the vertical direction. The axis Z3 of the attachment part 35a is located below the bracket axis Z2 by a height H4a in the vertical direction. The axis Z4 of the attachment part 35b is located below the bracket axis Z2 by a height H4b in the vertical direction. The axis Z5 of the attachment part 35c is located below the bracket axis Z2 by a height H4c in the vertical direction. In the present embodiment, the axes Z1 to Z5 are parallel to each other in the left-right direction, and have a height H4a<H3<H4b<H4c, but are not limited thereto.

16 is a perspective view showing the configuration near the front end of each

feedback rod

9, 10 in the hydraulic lifting device 100 of the second embodiment. FIG. 17 shows the positional relationship of the components of each transmission mechanism in the hydraulic lifting device 100 of the second embodiment, and corresponds to FIG. 13. As shown in FIGS. 14, 16, and 17, the draft feedback rod 10 is located between the position feedback rod 9 and the left side of the case 1 behind the approximately middle part of each

feedback rod

9, 10. On the other hand, the draft feedback rod 10 is located outside the position feedback rod 9 forward of the approximately middle part of each

feedback rod

9, 10. The hydraulic lifting device 100 of the second embodiment is provided with a cam 430a, a cam 230a, and a cam 11a at the front end of the position feedback rod 9 and the draft feedback rod 10. In this embodiment, the cam 430a, the cam 230a, and the cam 11a correspond to the first displacement transmission part, the second displacement transmission part, and the third displacement transmission part. Hereinafter, cam 430a, cam 230a, and cam 11a will be referred to as the first displacement transmission part 430a, the second displacement transmission part 230a, and the third displacement transmission part 11a.

The first displacement transmission section 430a is connected to the left end side of the second draft control shaft 430 so as to be able to rotate integrally with the second draft control shaft 430. The first displacement transmitting section 430a is capable of swinging in the front-rear direction about the axis A3. A lower end portion of the first displacement transmitting portion 430a is connected to the front end side 102 of the draft feedback rod 10 so as to be relatively rotatable. Therefore, when the bracket 3 rotates relative to each other, the first displacement transmitting section 430a rotates the second draft control shaft 430 according to the displacement of the draft feedback rod 10.

The second displacement transmission section 230a is connected to the left end side of the second position control shaft 230 so as to be able to rotate integrally with the second position control shaft 230. The second displacement transmitting portion 230a is capable of swinging in the front-rear direction about the axis A3. The lower end portion of the second displacement transmitting portion 230a is connected to the front end side 92 of the position feedback rod 9 so as to be relatively rotatable. Therefore, when the lift arm 2 relatively rotates, the second displacement transmitting section 230a rotates the second position control shaft 230 according to the displacement of the position feedback rod 9.

The third displacement transmitting portion 11a is a substantially triangular flat plate, and a fulcrum portion 11a1 is provided approximately in the center thereof. The fulcrum portion 11a1 is connected to a projection portion projecting leftward from the left side surface of the case 1 via a stepped bolt so as to be relatively rotatable. Thereby, the third displacement transmitting part 11a can rotate relative to the case 1 about the fulcrum part 11a1. The third displacement transmitting section 11a is configured to be able to press the first displacement transmitting section 430a when its front end side comes into contact with the first displacement transmitting section 430a. The rear end side of the third displacement transmission section 11a is connected to the second displacement transmission section 230a via the fourth displacement transmission section 11b.

The fourth displacement transmitting part 11b is a substantially rectangular flat plate, and the third displacement transmitting part 11a and the second displacement transmitting part 230a are connected to each other at both ends thereof so as to be relatively rotatable. The connecting portion of the fourth displacement transmitting portion 11b in the second displacement transmitting portion 230a is located above the front end side 92 of the position feedback rod 9.

As shown in FIG. 18, for example, when the position feedback rod 9 is displaced rearward due to the swinging of the lift arm 2, the second displacement transmitting section 230a swings rearward, and the second position control shaft 230 is rotated in direction R1 around axis A3. At this time, the fourth displacement transmitting section 11b is displaced backward in conjunction with the second displacement transmitting section 230a, and the third displacement transmitting section 11a is rotated using the fulcrum section 11a1 as a fulcrum. As a result, the front end side 11a2 of the third displacement transmitting portion 11a swings forward.

As shown in FIG. 19, the front end side 11a2 of the third displacement transmitting section 11a that swings forward approaches the first displacement transmitting section 430a, and eventually comes into contact with and presses the rear end side 430a1. Note that the rear end side 430a1 is configured to have a round bar shape extending left and right. As a result, the first displacement transmitting section 430a swings rearward and rotates the second draft control shaft 430 in the direction R1 around the axis A3. The spring 102a is contracted by the rearward swinging of the first displacement transmitting portion 430a. As a result, the portion of the draft feedback rod 10 rearward of the spring 102a is not displaced rearward, and the bracket 3 does not swing.

As explained above, in the hydraulic lifting device 100 according to the second embodiment of the present invention, the bracket axis Z2 is located above the lift arm axis Z1 in the first direction, and the bracket axis Z2 is located below the bracket axis Z2. On the sides are located mounting parts 35a-c, 36a-c with respective axes Z3, Z4, Z5 (see FIG. 15). By connecting the front end of the top link to the mounting portions 35a-c, 36a-c configured in this way, even when the bracket axis Z2 is located above the lift arm axis Z1, the top link The front end side of the can be positioned sufficiently downward. Therefore, effects similar to those obtained in the first embodiment described above can be obtained.

Further, in the second embodiment, in particular, a first displacement transmitting section 430a, a second displacement transmitting section 230a, a third displacement transmitting section 11a, and a fourth displacement transmitting section 11b are provided near the front end of each

feedback rod

9, 10. , equipped. The third displacement transmitting section 11a is configured such that its front end side 11a2 can come into contact with the rear end side 430a1 of the first displacement transmitting section 430a and press the third displacement transmitting section 11a. The third displacement transmitting section 11a is adapted to rotate in conjunction with the rotation of the second displacement transmitting section 230a via the fourth displacement transmitting section 11b, using the fulcrum section 11a1 as a fulcrum (see FIGS. 19).

Therefore, in order to link the second draft control shaft 430 with the rotation of the second position control shaft 230, the displacement of the second displacement transmission part 230a can be transmitted to the first displacement transmission part 430a via the third displacement transmission part 11a. In the third displacement transmission part 11a, the input from the second displacement transmission part 230a can be made to undergo rotational displacement with the fulcrum part 11a1 as the fulcrum. On the other hand, the first displacement transmission part 430a, which receives a load from the third displacement transmission part 11a, also undergoes rotational displacement. Therefore, the load direction and the displacement direction can be brought closer together, so that the application of excessive force can be suppressed. Furthermore, the relatively strong front end side 11a2 of the third displacement transmission part 11a and the rear end side 430a1 of the first displacement transmission part 430a can be used as the abutment/pressure parts. For example, a configuration is also conceivable in which the oscillating second displacement transmission part 230a abuts and presses against the draft feedback rod 10 to link the second draft control shaft 430. In this case, the input from the second displacement transmission part 230a is directly transmitted to the draft feedback rod 10, which may cause bending or deformation of the draft feedback rod 10. On the other hand, as described above, the configuration of the second embodiment can reliably transmit displacement while suppressing bending or deformation of the linked parts.

[Modified example]
In the first embodiment, the draft feedback rod 10 is provided with the protrusion 102b, and the swinging cam 230a contacts and presses the protrusion 102b. Instead, the first displacement transmitting section 430a, the second displacement transmitting section 230a, and the third displacement transmitting section 11a of the second embodiment are provided near the front end of each

feedback rod

9, 10, and the second displacement transmitting section The displacement of the transmission section 230a may be configured to be transmitted to the first displacement transmission section 430a via the third displacement transmission section 11a.

In each of the embodiments described above, the bracket shaft 33 is configured to generate a biasing force during relative rotation according to the traction load, but instead, for example, the other end side 32 of the bracket 3 is It may also have only the function of being pivotally supported at the outer rear end of. In this case, the bracket shaft 33 does not have the biasing function required to perform draft control. For this reason, for example, a separate biasing mechanism may be interposed between the case 1 and the bracket 3, the bracket axis Z2 may be positioned below or above the lift arm axis Z1 to the extent possible, and the mounting portions 35a to 35c may be , 36a to 36c may be located below the bracket axis Z2 to the extent possible.

In each of the above embodiments, the co-rotating shaft 221 of the first position control shaft 220 is coaxially fitted into the co-rotating shaft 421 of the first draft control shaft 420 . Instead, the co-rotating shaft 221 of the first position control shaft 220 has a hollow structure, and the co-rotating shaft 221 of the first draft control shaft 420 has a co-rotating shaft 221 of the first draft control shaft 420. , may be fitted coaxially.

In each of the above embodiments, the reverse rotation shaft 422 of the first draft control shaft 420 is coaxially fitted into the reverse rotation shaft 222 of the first position control shaft 220. Instead, the reverse rotation shaft 422 of the first draft control shaft 420 has a hollow structure, and the reverse rotation shaft 222 of the first position control shaft 220 has a hollow structure. , may be fitted coaxially.

In each of the above embodiments, the second position control shaft 230 is coaxially fitted into the second draft control shaft 430. Alternatively, the second position control shaft 230 may have a hollow structure, and the second draft control shaft 430 may be coaxially fitted into the second position control shaft 230.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 : Case 2 : Lift arm 21 : One end side 22 : Other end side 23 : Lift arm shaft 3 : Bracket 31 : One end side 32 : Other end side 33 : Bracket shaft 35a : Attachment part 35b : Attachment part 35c : Attachment part 36a : Attachment part 36b : Attachment part 36c : Attachment part 4 : Hydraulic cylinder 5 : Control valve 51 : Spool 6 : Position control lever 61 : One end side 62 : Other end side 7 : Pumper lever 71 : One end side 72 : Other end side 74 : Rotation regulating part 8 : Draft control lever 81 : One end side 82 : Other end side 9 : Position feedback rod 91 : Rear end side 92 : Front end side 10 : Draft feedback rod 101 : Rear end side 102 : Front end side 11a : Third Displacement transmission section 11a1: Fulcrum section 11a2: Front end side 11b: Fourth displacement transmission section 100: Hydraulic lifting device 20: Position control transmission mechanism 210: Position control cam 220: First position control shaft 221: Same direction rotation shaft 222: Reverse Directional rotation shaft 223: Rotation transmission section 230: Second position control shaft 230a: Second displacement transmission section 30: Pumper transmission mechanism 310: Pumper cam 320: Pumper shaft 330: Rotation transmission section 40: Draft control transmission mechanism 410: Draft control cam 420: First draft control shaft 421: Same direction rotation shaft 422: Opposite direction rotation shaft 423: Rotation transmission section 430: Second position control shaft 430a: First displacement transmission section 430a1: Rear end side Z1: Lift arm axis Z2: bracket axis

Claims

case and
a hydraulic cylinder located inside the case and driven according to supply and discharge of hydraulic oil;
A control valve located inside the case and having a spool in the flow path of the hydraulic oil, the control valve allowing and regulating supply and discharge of the hydraulic oil to the hydraulic cylinder according to the position of the spool. valve and
A lift arm is located outside the case and has one end and the other end defined, the one end being configured to be connectable to an object, and the other end being connected to the object when the hydraulic cylinder is driven. a lift arm configured to be able to lift and lower the connected object by rotating relative to the case as a fulcrum;
A bracket located outside the case and defined by one end side and the other end side, the one end side is configured to be connectable to a target object, and according to the traction load from the connected target object, a bracket that rotates relative to the case using the other end as a fulcrum;
a draft control lever located outside the case and configured to be movable in response to an operator's operation;
a draft feedback rod located outside the case and configured to be displaceable according to relative rotation of the bracket;
When the draft control lever is operated, the displacement of the draft control lever is transmitted toward the spool, and the position of the spool is displaced toward a side where supply and discharge of the hydraulic oil is permitted, and the bracket is a draft control transmission mechanism that transmits the displacement of the draft feedback rod toward the spool and displaces the position of the spool toward a side that regulates the supply and discharge of the hydraulic oil;
In a hydraulic lifting device equipped with
The lift arm is
a lift arm axis that is an axis of the relative rotation with respect to the case and that is an axis that extends in a second direction orthogonal to a first direction that is the upward and downward direction of the object;
The bracket is
a bracket axis that is an axis of relative rotation with respect to the case and that extends in the second direction and is located parallel to the lift arm axis;
an attachment part configured to be able to attach the object and located below the bracket axis in the first direction;
Hydraulic lifting device with.
The hydraulic lifting device according to claim 1,
The bracket is
The hydraulic lifting device is configured such that the bracket shaft is located lower than the lift arm shaft in the first direction.
The hydraulic lifting device according to claim 1,
The bracket is
The hydraulic lifting device is configured such that the bracket shaft is located above the lift arm shaft in the first direction.
In the hydraulic lifting device according to claim 2 or 3,
A bracket shaft that pivotally supports the other end of the bracket on the case and is disposed coaxially with the bracket shaft, and is configured to generate a biasing force upon relative rotation according to the traction load. Hydraulic lifting device further equipped with.
In the hydraulic lifting device according to claim 2 or 3,
The draft control transmission mechanism includes:
a first draft control shaft that rotates around an axis in response to displacement of the draft control lever when the draft control lever is operated;
a second draft control shaft that is located above the first draft control shaft in the vertical direction of the object and rotates around an axis in accordance with the displacement of the draft feedback rod when the bracket rotates relative to each other;
When the first draft control shaft rotates, the position of the spool is displaced toward a side where supply and discharge of the hydraulic oil is allowed according to the rotation of the first draft control shaft, and the second draft control shaft is rotated. a draft control cam that, when rotated, displaces the position of the spool in accordance with the rotation of the second draft control shaft toward a side that regulates supply and discharge of the hydraulic oil;
Hydraulic lifting device with.
The hydraulic lifting device according to claim 5,
The draft control lever is
One end side and the other end side are defined, and the one end side is configured to be operable by the operator, and configured to be able to rotate relative to the case with the other end side as a fulcrum as a displacement in response to the operation. ,
The first draft control shaft is
a co-rotating shaft connected to the other end of the draft control lever and configured to be rotatable in the same direction as the rotation direction of the draft control lever;
a reverse rotation shaft connected to the draft control cam and configured to be rotatable in a direction opposite to the rotation direction of the draft control lever;
When the draft control lever relatively rotates, the rotation of the same-direction rotating shaft is transmitted to the opposite-direction rotating shaft, and the opposite-direction rotating shaft is transmitted in a direction opposite to the rotation direction of the same-direction rotating shaft. a rotation transmission unit that rotates the
Hydraulic lifting device with.
The hydraulic lifting device according to claim 5,
a position control lever located outside the case and configured to be movable in response to an operation by an operator;
a position feedback rod located outside the case and configured to be displaceable according to relative rotation of the lift arm;
When the position control lever is operated, the displacement of the position control lever is transmitted toward the spool, and the position of the spool is displaced toward the side where supply and discharge of the hydraulic oil is permitted, and the lift arm a position control transmission mechanism that transmits the displacement of the position feedback rod toward the spool and displaces the position of the spool toward a side that regulates supply and discharge of the hydraulic oil when the position feedback rod rotates relative to the
In a hydraulic lifting device equipped with
The position control transmission mechanism is
a first position control shaft that rotates around an axis in response to displacement of the position control lever when the position control lever is operated;
a second position control shaft that is located above the first position control shaft in the lifting direction of the object and rotates about the axis according to the displacement of the position feedback rod when the lift arm rotates relative to the lift arm; ,
When the first position control shaft rotates, the position of the spool is displaced toward a side where supply and discharge of the hydraulic oil is permitted according to the rotation of the first position control shaft, and the second position control shaft is rotated. a position control cam that, when rotated, displaces the position of the spool in accordance with the rotation of the second position control shaft toward a side that regulates supply and discharge of the hydraulic oil;
Hydraulic lifting device further equipped with.
The hydraulic lifting device according to claim 7,
The second draft control shaft is connected to the second draft control shaft so as to be integrally rotatable, and is connected to the draft feedback rod so as to be relatively rotatable, and when the bracket rotates relatively, the second a first displacement transmission section that rotates the draft control shaft;
The lift arm is connected to the second position control shaft so as to be integrally rotatable, and is connected to the position feedback rod so as to be relatively rotatable. a second displacement transmission section that rotates a two-position control shaft;
The position feedback rod is configured to be able to abut and press the first displacement transmitting section and to rotate relative to the case in conjunction with rotation of the second displacement transmitting section, and the position feedback rod is displaced and the second displacement transmitting section is moved. a third displacement transmitting section that rotates the first displacement transmitting section by rotating relative to the case and pressing while abutting the first displacement transmitting section when the displacement transmitting section rotates;
Hydraulic lifting device further equipped with.
The hydraulic lifting device according to claim 7 or 8,
Either one of the first draft control shaft and the first position control shaft has a hollow structure, and is configured such that the other can be coaxially fitted into the inside of the one;
Either one of the second draft control shaft and the second position control shaft has a hollow structure, and is configured such that the other can be coaxially fitted into the interior of the one;
The draft control transmission mechanism and the position control transmission mechanism are
The other is coaxially fitted into one of the first draft control shaft and the first position control shaft, and the other is fitted into one of the second draft control shaft and the second position control shaft. Fitted coaxially,
In response to displacement of either the draft control lever or the position control lever, the first draft control shaft and the first position control shaft rotate relative to each other around their axes, and
A hydraulic lifting device configured such that the second draft control shaft and the second position control shaft rotate relative to each other around an axis in response to displacement of either one of the draft feedback rod and the position feedback rod.
The hydraulic lifting device according to claim 5,
The first position is located outside the case and is an arbitrary position in a state where supply and discharge of the hydraulic oil is regulated by the control valve. a pumper lever configured to be movable to a different second position;
When the pumper lever is operated to be displaced from the first position to the second position, the displacement of the pumper lever is transmitted toward the spool, and the position of the spool is changed to allow the supply and discharge of the hydraulic oil. When the pumper lever is displaced toward the permissible side and the lift arm is relatively rotated with the pump lever positioned at the second position, the displacement of the position feedback rod is transmitted toward the spool, and a pump transmission mechanism that displaces the position of the spool toward a side that regulates supply and discharge of the hydraulic oil;
further comprising;
The pump transmission mechanism includes:
a pumper shaft that rotates around an axis in response to displacement of the pumper lever when the pumper lever is operated and displaced from the first position to the second position;
When the pumper shaft rotates, the position of the spool is displaced toward a side where supply and discharge of the hydraulic oil is allowed according to the rotation of the pumper shaft, and when the second position control shaft rotates, the a pump cam that displaces the position of the spool toward a side that regulates supply and discharge of the hydraulic oil according to rotation of a second position control shaft;
Hydraulic lifting device with.
The hydraulic lifting device according to claim 10,
The pumper lever is
One end side and the other end side are defined, and the one end side is configured to be operable by the operator, and configured to be able to rotate relative to the case with the other end side as a fulcrum as a displacement in response to the operation. ,
A hydraulic lifting device comprising: a rotation regulating section that regulates the relative rotation of the pumper lever.