Offset work machine

Abstract

To prevent a malfunction caused when a work unit comes in contact with an obstacle.SOLUTION: An offset work machine includes a work unit, an escape mechanism unit, an offset mechanism unit having an arm unit, and a first connection unit for connecting the arm unit with the escape mechanism unit. The escape mechanism unit has an elastic member, a turning connecting member, and a second connection unit for connecting the elastic member with the turning connecting member. The first connection unit can turn centering on the turning shaft of the turning connecting member. The second connection unit is movable along with the turning of the turning connecting member. The elastic member biases the second connection unit in the direction for preventing the turning connecting member from being turned when external force acts on the work unit. When the external force acts on the work unit, an angle formed by the direction acting on the first connection unit from the arm unit and the direction in which the first connection unit is going to move along with the turning of the turning connecting member by the external force is configured so that a smaller case may become small in comparison with the case where an offset moving amount is large.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an offset work machine, and more particularly to an offset-type work machine that is attached to the rear of a traveling machine body and performs agricultural work to the side of the traveling machine body. [Background technology]

[0002] Conventionally, mowers have been known as working machines used to mow grass to remove weeds from farm roads and wastelands. Generally, mowers are attached to a traveling body such as a tractor, and the mower performs the mowing work by operating the working unit while moving together with the traveling body. In recent years, offset-type mowers have become known in which the working unit that performs the mowing work moves offset to the side of the traveling body, and mows the grass to the side of the traveling body (Patent Documents 1 and 2). The mowers described in Patent Documents 1 and 2 have a parallel link mechanism between the attachment unit attached to the traveling body and the working unit that performs the mowing work, and this parallel link mechanism enables the working unit to be offset to the side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-39941 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-191864 Summary of the Invention [Problem to be solved by the invention]

[0004] In the brush cutters described in Patent Documents 1 and 2, when mowing in an offset position that protrudes laterally from the running body, the working unit may get caught on an obstacle such as a rock or stump hidden in the grass. In this case, a large load is placed on the frame of the working unit, the electric cylinder, etc., which may result in damage to the brush cutter. Furthermore, since a load is also placed on the running body, this may lead to damage to parts of the running body. Furthermore, if the running body continues to travel with the working unit caught on an obstacle, the running body will rotate around the obstacle, significantly changing its direction of travel, which may lead to an accident.

[0005] The present invention has been made in view of the above problems, and one of its objects is to prevent problems that occur when a working unit comes into contact with an obstacle. [Means for solving the problem]

[0006] An offset work machine in one embodiment of the present invention comprises a working unit that receives power from a traveling machine body to perform agricultural work, an escape mechanism for causing the working unit to move away from the working unit when an external force equal to or greater than a predetermined force acts on the working unit, an offset mechanism having an arm extending from the working unit toward the escape mechanism and causing the working unit to move in an offset manner in the left and right direction, and a first connecting part connecting the arm and the escape mechanism, the escape mechanism comprising an elastic member, a pivotable connecting member connected to the first connecting part and pivotable about a pivot axis, and a second connecting part connecting the elastic member and the pivotable connecting member. the first connecting portion is rotatable around the rotation axis, the second connecting portion is movable in association with the rotation of the rotary connecting member, the elastic member biases the second connecting portion in a direction that prevents the rotary connecting member from rotating when an external force acts on the working unit, and when the external force acts on the working unit, the angle formed between the direction of action from the arm portion to the first connecting portion and the direction in which the first connecting portion attempts to move in association with the rotation of the rotary connecting member due to the external force is smaller when the amount of offset movement is small than when it is large.

[0007] The offset mechanism may include a parallel link mechanism, the arm may constitute a link of the parallel link mechanism, and the first connecting portion may constitute a joint of the parallel link mechanism.

[0008] The pivotal connecting member may have a first sliding portion extending in a first direction in which the distance from the pivotal axis changes, and the second connecting portion may approach the pivotal axis by sliding on the first sliding portion in the first direction.

[0009] The escape mechanism may further have a first member having a second sliding portion extending in a second direction different from the first direction, in which the distance from the pivot axis changes, and the second connecting portion is pushed by the first sliding portion while sliding on the first sliding portion, thereby sliding on the second sliding portion in the second direction and approaching the pivot axis, and the elastic member may extend or contract while rotating relative to the frame due to the movement of the second connecting portion.

[0010] The first member may include a second region continuous with the first region in which the second sliding portion is provided, the second region being a region in which the second connecting portion is movable in a third direction different from the second direction, and the angle formed between the third direction and the first direction when the second connecting portion is positioned in the second region may be larger than the angle formed between the second direction and the first direction when the second connecting portion is positioned in the first region. [Effects of the Invention]

[0011] The offset working machine according to one embodiment of the present invention can prevent problems that occur when the working unit comes into contact with an obstacle. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a plan view showing a configuration of an offset working machine according to an embodiment of the present invention. [Figure 2] 1 is a plan view showing a configuration of an offset working machine according to an embodiment of the present invention. [Figure 3]FIG. 10 is an explanatory diagram showing a state in which the working unit has been offset to the right and moved before coming into contact with an obstacle in the offset working machine according to one embodiment of the present invention. [Figure 4] 3 is an exploded view of a flat plate-shaped member and a rotary connecting member in the offset work machine according to one embodiment of the present invention. FIG. [Figure 5] 1 is an explanatory diagram showing a state before a working unit of an offset working machine according to an embodiment of the present invention comes into contact with an obstacle. FIG. [Figure 6] 10 is an explanatory diagram showing a state after the working unit of the offset working machine according to one embodiment of the present invention has come into contact with an obstacle. FIG. [Figure 7] 3 is an exploded view of a flat plate-shaped member and a rotary connecting member in the offset work machine according to one embodiment of the present invention. FIG. [Figure 8] 3 is an exploded view of a flat plate-shaped member and a rotary connecting member in the offset work machine according to one embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the offset working machine of the present invention will be described with reference to the drawings. However, the offset working machine of the present invention can be embodied in many different forms, and should not be construed as being limited to the description of the example shown below. In the drawings referred to in this embodiment, the same parts or parts having similar functions are given the same reference numerals, and repeated explanations thereof will be omitted.

[0014] For ease of explanation, terms indicating directions such as "up," "down," "front," "rear," "right," and "left" are used, but for the offset work machine of the present invention, the direction in which gravity acts is "down," and the opposite is "up." Furthermore, the direction in which the traveling body moves is "front," and the opposite is "rear." Furthermore, facing "front," the right side is "right" and the left side is "left." The side closer to the centerline of the offset work machine is called the "inner" side, and the side farther away is called the "outer" side.

[0015] [1. First embodiment] [1-1. Configuration of offset work machine] 1 is a plan view showing the configuration of an offset working machine 100 according to a first embodiment. In this embodiment, an offset-type mower is shown as an example of the offset working machine 100. However, the offset working machine 100 is not limited to a mower, and may be other offset-type working machines such as a ridger or plow.

[0016] As shown in FIG. 1, the offset work machine 100 of this embodiment includes a mounting unit 10, an offset mechanism unit 20, a power transmission unit 30, a working unit 40, and an escape mechanism unit 50. The offset work machine 100 is connected to a traveling machine body (not shown) such as a tractor by the mounting unit 10. The mounting unit 10 and the working unit 40 are connected via the offset mechanism unit 20 and the power transmission unit 30. With this configuration, the offset work machine 100 moves forward as the traveling machine body travels. While the offset work machine 100 moves, the working unit 40 operates by power received from the traveling machine body to perform grass cutting work.

[0017] The mounting unit 10 is a portion that is connected to a three-point link mechanism (not shown) provided on the traveling machine body. Specifically, the mounting unit 10 in this embodiment includes a front frame 11, a top link connection (top mast) (not shown), a lower link connection (lower link pin) 13, an input shaft 14, a power transmission means 15, and an output shaft 16. The top link connection and the lower link connection 13 may be connected to the three-point link mechanism of the traveling machine body via an auto hitch arm (not shown). In this embodiment, the output shaft 16 is provided at a position offset in the D2 direction from the input shaft 14 in the left-right direction. The front frame 11 is provided with the top link connection and the lower link connection 13. The front frame 11 is a member that extends in the left-right direction and functions as a support frame for supporting the offset work machine 100 on the traveling machine body via the top link connection and the lower link connection 13.

[0018] The offset mechanism 20 is disposed between the mounting unit 10 (front frame 11) and the working unit 40, connects the mounting unit 10 and the working unit 40, and moves the working unit 40 in the left-right direction by rotating with respect to the mounting unit 10. In this embodiment, the offset mechanism 20 includes a parallel link mechanism that is rotatably connected to the front frame 11 and the working unit 40. That is, by rotating the offset mechanism 20 with respect to the front frame 11, the working unit 40 can be moved in the left-right direction (direction D2) while maintaining the orientation of the working unit 40 with respect to the traveling direction (direction D1). In other words, the offset mechanism 20 can offset and move the working unit 40 to the side with respect to the traveling direction of the traveling machine body.

[0019] 2 is a plan view of the offset work machine 100 of the first embodiment, omitting the illustration of the power transmission unit 30. As shown in FIG. 2, the offset mechanism unit 20 of this embodiment has a first link arm 21, a second link arm 22, a third link arm 23, and an expandable member 24.

[0020] 1, the first link arm 21 is disposed below and overlaps the power transmission unit 30. One front end of the first link arm 21 is rotatably connected to the front frame 11 of the mounting unit 10 at a connection part 201, and the other rear end (rotation fulcrum 25) of the first link arm 21 is rotatably connected to the third link arm 23 and the working unit 40.

[0021] The second link arm 22 extends from the working unit 40 toward the relief mechanism 50. The second link arm 22 is disposed substantially parallel to the first link arm 21 at a distance therefrom and has a length approximately equal to that of the first link arm 21. One front end of the second link arm 22 is rotatably and movably connected to the relief mechanism 50 provided on the front frame 11 of the mounting unit 10, and the other rear end of the second link arm 22 is rotatably connected to the third link arm 23. Note that, as will be described in detail later, one front end of the second link arm 22 is rotatably connected to a pin-shaped connecting portion 203 (first connecting portion), and the second link arm 22 is configured to be rotatable relative to the relief mechanism 50 via the connecting portion 203. In other words, the connecting portion 203 provided at one front end of the second link arm 22 functions as a fulcrum for the offset movement. Note that the detailed connection structure between the connecting portion 203 and the relief mechanism 50 will be described later.

[0022] The third link arm 23 is disposed substantially parallel to the front frame 11 and interconnects the first link arm 21 and the second link arm 22. One end (the pivot point 25 side) of the third link arm 23 connected to the first link arm 21 is fixed to the working unit 40, and is configured so that the positional relationship between the third link arm 23 and the working unit 40 does not change.

[0023] With the above configuration, the front frame 11, the first link arm 21, the second link arm 22, and the third link arm 23 form a quadrilateral link mechanism with each of them serving as a side (link). The connecting portion 203 corresponds to a pair (joint) of the parallel link mechanism. With this link mechanism, the offset mechanism 20 can offset and move the working unit 40 in the left-right direction while maintaining the orientation of the working unit 40 so that the longitudinal direction of the working unit 40 is approximately parallel to the left-right direction.

[0024] The telescopic member 24 is a power source (actuator) that drives the offset mechanism 20, and is formed, for example, by an electric cylinder or a hydraulic cylinder. One end of the telescopic member 24 is rotatably connected to the connecting portion 203 together with the front end of the second link arm 22. As described above, the connecting portion 203 is connected to the escape mechanism 50, and therefore the front end of the second link arm 22 can be said to be connected to the front frame 11 via the escape mechanism 50 (a pair of flat plate-shaped members 570). The other rear end of the telescopic member 24 is connected to the first link arm 21 via a bracket provided near the center of the first link arm 21 (or slightly rearward from the center). The telescopic movement of the telescopic member 24 rotates the first link arm 21, driving the offset mechanism 20. The offset amount (the amount of movement in the offset direction) of the working unit 40 is controlled by the amount of extension and contraction of the telescopic member 24.

[0025] Returning to Fig. 1 for the explanation, the power transmission unit 30 is a mechanism for transmitting power transmitted from the traveling machine body via the input shaft 14 of the mounting unit 10, the power transmission means 15 (the sprocket 152 and the intermediate shaft 154), and the output shaft 16 to the working unit 40. As described above, the power transmission unit 30 is disposed overlapping a part of the offset mechanism unit 20, specifically, the upper side of the first link arm 21.

[0026] The offset work machine 100 of this embodiment uses a chain drive mechanism as the power transmission unit 30. Specifically, the power transmission unit 30 has at least a drive sprocket 31, a driven sprocket 32, and a roller chain 33. The roller chain 33 is configured to be wound around a pair of sprockets (the drive sprocket 31 and the driven sprocket 32).

[0027] The drive sprocket 31 is a gear that rotates in engagement with the rotating output shaft 16, thereby transmitting the power received from the output shaft 16. The driven sprocket 32 ​​is a gear that rotates passively by the power transmitted from the drive sprocket 31 via a roller chain 33. The roller chain 33 is a member that transmits power, etc., using tension. Note that the power transmission unit 30 is not limited to a chain drive mechanism, and may be configured as a belt drive mechanism using a pair of pulleys and a belt.

[0028] The front of the power transmission unit 30 is rotatably connected to the mounting unit 10 (front frame 11), and the rear of the power transmission unit 30 is rotatably connected to the working unit 40. In this embodiment, the rotation center of the power transmission unit 30 relative to the mounting unit 10 coincides with the rotation center of the drive sprocket 31. In other words, the rotation center of the power transmission unit 30 relative to the mounting unit 10 coincides with the rotation center of the output shaft 16. In addition, the rotation center of the power transmission unit 30 relative to the working unit 40 coincides with the rotation center of the driven sprocket 32.

[0029] Furthermore, the rotation center of the power transmission unit 30 relative to the mounting unit 10 coincides with the rotation center of the offset mechanism unit 20 (specifically, the first link arm 21) relative to the mounting unit 10. In this manner, in this embodiment, the first link arm 21, which is part of the offset mechanism unit 20, and the power transmission unit 30 rotate integrally relative to the mounting unit 10 (front frame 11), so a large offset amount can be ensured without being restricted by a bending angle as occurs when a universal joint is used for power transmission. Also, when the working unit 40 is stored (not working), it can be positioned close to the traveling machine body in the fore-and-aft direction.

[0030] The working unit 40 is the part that performs the grass cutting work, and includes a work rotor 41 and a blade drive unit 42. The working unit 40 performs the grass cutting work by having the blade drive unit 42 receive power transmitted from the power transmission unit 30 to drive the work rotor 41. The work rotor 41 includes a tine shaft 41a and multiple cutting blades 41b radially arranged on the tine shaft 41a. The tine shaft 41a extends in the left-right direction, approximately perpendicular to the traveling direction of the traveling machine body. The work rotor 41 performs grass cutting by rotating the multiple cutting blades 41b together with the tine shaft 41a. The blade drive unit 42 transmits the power transmitted by the power transmission unit 30 to the tine shaft 41a of the work rotor 41. The blade drive unit 42 may be a chain drive mechanism having a configuration similar to that of the power transmission unit 30, or may be a belt drive mechanism.

[0031] The relief mechanism 50 is provided on the front frame 11. The relief mechanism 50 includes a pair of upper and lower flat plate-like members 570 and an elastic member 600. As will be described in detail later, the pair of flat plate-like members 570 are provided parallel to the upper surface of the front frame 11 and sandwich the front frame 11 from above and below. One end of the elastic member 600 is rotatably connected to a pin-shaped connecting portion 603, and the elastic member 600 is rotatably connected to the pair of flat plate-like members 570 via a pivot shaft member 610. As will be described in detail later, the relief mechanism 50 has a function of moving the working unit 40 diagonally backward to escape when an external force equal to or greater than a predetermined force acts on the working unit 40. The escape movement means that when the working unit 40 receives an external force equal to or greater than the predetermined force, the relief mechanism 50 functions to move the working unit 40 backward while tilting its orientation relative to the traveling direction of the working unit 40 during operation.

[0032] [1-2. Detailed configuration of the escape mechanism 50] FIG. 3 is an explanatory diagram showing a state in which a working unit that has been offset to the right and moved in an offset work machine according to one embodiment of the present invention has not yet come into contact with an obstacle. FIG. 4 is an exploded view of the flat plate-shaped members and the pivotal connecting member in the offset work machine according to one embodiment of the present invention. FIG. 3B is a partially enlarged view of the escape mechanism 50. A pair of flat plate-shaped members 570 are arranged parallel to the upper surface of the front frame 11 and sandwich the front frame 11 from above and below, but FIG. 3B does not show the upper flat plate-shaped member of the pair of flat plate-shaped members 570. FIG. 4 is an exploded view showing the pair of flat plate-shaped members 570 and the pivotal connecting member 700 of the escape mechanism 50 shown in FIG. 3B. The detailed configuration of the escape mechanism 50 will be described below using FIGS. 3B and 4. The offset work machine 100 shown in FIG. 3 shows the case where the offset amount is maximum.

[0033] As shown in FIG. 3B, the escape mechanism 50 includes a flat member 570, an elastic member 600, a pivotable connecting member 700, and a connecting portion 603 (second connecting portion). The pivotable connecting member 700 connects the second link arm 22 (arm portion) and the elastic member 600 while rotating about a pivot shaft 705. The connecting portion 603 connects the elastic member 600 and the pivotable connecting member 700. The connecting portion 203 connects the second link arm 22 and the pivotable connecting member 700. With the above configuration, when the second link arm 22 presses the connecting portion 203, the pivotable connecting member 700 is rotated by the connecting portion 203, and the connecting portions 203 and 603 rotate about the pivot shaft 705 as the pivotable connecting member 700 rotates. As the connecting portion 603 rotates, the elastic member 600 expands and contracts.

[0034] The elastic member 600 includes a rotating shaft member 610, a contact member 620, and a shaft member 630. The rotating shaft member 610 is rotatably connected to the pair of flat plate-like members 570. The rotating shaft member 610 allows the orientation of the elastic member 600 relative to the pair of flat plate-like members 570 to be changed. The contact member 620 is connected (fixed) to the shaft member 630, and is rotatably connected to the connecting portion 603. The shaft member 630 is inserted inside the elastic member 600, passes through a through-hole provided in the rotating shaft member 610, and is fixed to the contact member 620. The shaft member 630 slides against the inner wall of the through-hole provided in the rotating shaft member 610, causing the elastic member 600 to expand and contract.

[0035] The elastic member 600, the contact member 620, and the shaft member 630 rotate around the rotating shaft member 610. In other words, the elastic member 600, the contact member 620, and the shaft member 630 are connected to the pair of flat plate-shaped members 570 by the rotating shaft member 610 so as to be able to rotate.

[0036] The elastic member 600 is disposed between the front end 631 of the shaft member 630 and the pivot shaft member 610 so as to press (bias) them together. That is, the elastic member 600 is disposed between the end 631 and the pivot shaft member 610 in a state slightly contracted from its free length. Due to the bias of the elastic member 600 as described above, a forward biasing force acts on the abutting member 620, the shaft member 630, and the connecting portion 603 connected to the abutting member 620, thereby maintaining the working unit 40 facing squarely in the direction of travel. When an external force acts on the working unit 40 from the front, a force F1 is applied to the connecting portion 203 by the second link arm 22 in the extension direction (axial direction) of the second link arm 22, and the pivot connecting member 700 receives a counterclockwise rotational force from the connecting portion 203. Due to this rotational force, the connecting portion 603 receives a rearward force (a direction away from the elastic member 600) from the pivot connecting member 700. The elastic member 600 biases the connecting part 603 forward to suppress this rearward force. When an external force greater than a predetermined force is applied to the working unit 40, the force attempting to move the connecting part 603 rearward exceeds the forward biasing force of the elastic member 600, causing the above-mentioned parallel link mechanism to collapse and causing the working unit 40 to escape in the clockwise direction. In other words, the elastic member 600 biases the connecting part 603 in a direction that suppresses the counterclockwise rotation of the rotating connecting member 700, and functions to keep the working unit 40 facing directly in the direction of travel except when a predetermined external force is applied.

[0037] 3(B) and 4, the flat plate-shaped member 570 is provided with a movement limiting portion 502 that limits the movement range of the connecting portion 203, a movement limiting portion 503 that limits the movement range of the connecting portion 603, and an insertion hole 505 through which the pin-shaped rotation shaft 705 is inserted. The movement limiting portions 502 and 503 are formed by grooves (through holes) provided in each of the pair of flat plate-shaped members 570.

[0038] As shown in FIG. 4, the movement limiting portion 502 is provided in an arc shape centered on the rotation axis 705. The dashed-dotted line overlapping the movement limiting portion 502 is part of the arc centered on the rotation axis 705. The movement limiting portion 502 limits the movement of the connecting portion 203 inserted into the second link arm 22 to a range from one end to the other end of the arc-shaped movement limiting portion 502. The movement limiting portion 503 has a shape in which a region 585 extending (having a longitudinal direction) in the D3 direction and a circular arc-shaped region 586 centered on the rotation axis 705 are continuous. The region 585 may be referred to as the "first region." The region 586 may be referred to as the "second region."

[0039] The dashed-dotted line overlapping with region 586 of movement limiting portion 503 is part of an arc centered on rotation axis 705. The dashed-two-dotted line overlapping with region 585 of movement limiting portion 503 is a line extending in direction D3 and corresponds to the center line of region 585 extending in direction D3. Direction D3 is the direction in which the distance from rotation axis 705 changes. Movement limiting portion 503 limits the movement of connecting portion 603 inserted into contact member 620. The connecting portion 603 slides on the inner wall on the rear side of movement limiting portion 503 in region 585, thereby restricting the movement of connecting portion 603 and moving connecting portion 603 closer to rotation axis 705. Direction D3 may be referred to as the "second direction." In region 586, the direction in which connecting portion 603 is movable may be referred to as the "third direction." The third direction is different from the second direction. The pair of flat plate-like members 570 may be referred to as "first members."

[0040] The front end of region 586 may be referred to as first end 511, and the rear end of region 585 may be referred to as second end 521. The point where region 585 and region 586 are connected may be referred to as bent portion 515. Connecting portion 603 moves in an arc shape centered on pivot shaft 705 between first end 511 and bent portion 515. That is, in region 586 (second region), the distance between connecting portion 603 and pivot shaft 705 does not change. Meanwhile, connecting portion 603 moves in direction D3 between bent portion 515 and second end 521. The D3 direction, which starts from a point on the arc centered on pivot shaft 705, is the direction toward the inside of the circle. Therefore, as described above, when connecting portion 603 moves in direction D3 through region 585 (second sliding portion) of movement limiting portion 503, the distance between connecting portion 603 and pivot shaft 705 becomes shorter.

[0041] The rotary connecting member 700 is sandwiched between a pair of upper and lower flat plate-shaped members 570. The rotary connecting member 700 is rotatably connected to the flat plate-shaped members 570 via a rotary shaft 705. The rotary connecting member 700 has a connecting portion 710 and a sliding portion 720. The connecting portion 710 is a groove (or a through-hole) into which the connecting portion 203 can be inserted and is rotatably connected to the connecting portion 203. The sliding portion 720 is a groove (or a through-hole) into which the connecting portion 603 can be inserted and is rotatably and slidably connected to the connecting portion 603. The long side of the sliding portion 720 is in the D4 direction. The D4 direction is the direction in which the distance from the rotary shaft 705 changes. In this embodiment, the rotary shaft 705 is provided on an extension line of the sliding portion 720 in the D4 direction. The D4 direction may be referred to as the "first direction."

[0042] The connecting portion 603 slides in the direction D4 on the inner wall on the front side of the sliding portion 720. As the connecting portion 603 slides on the sliding portion 720, the distance between the connecting portion 603 and the rotation shaft 705 changes. The abutting member 620 (see FIG. 3) is connected to the sliding portion 720 via the pin-shaped connecting portion 603. That is, the connecting portion 603 inserted into the sliding portion 720 is movable along the sliding portion 720 in the direction D4, and therefore the connecting portion 603 can move in the direction D3 in the region 585 of the movement restricting portion 503.

[0043] 3, the elastic member 600 has a function of holding the connecting portion 603 at the first end portion 511 when no external force exceeding a predetermined threshold is applied to the working unit 40. In other words, the elastic member 600 indirectly biases the connecting portion 203 via the connecting portion 603 and the pivotal connecting member 700 so that the connecting portion 203 is held at a predetermined position of the movement limiting portion 502 (in this embodiment, the rear end position of the movement limiting portion 502).

[0044] The pivot shaft member 610 is inserted through a pivot center 590 (see FIG. 4 ) that is pivotably provided on the flat plate-shaped member 570. Therefore, as the connecting portion 603 moves, the elastic member 600 pivots about the pivot center 590 relative to the flat plate-shaped member 570. In this manner, the elastic member 600 is configured to be pivotable relative to the flat plate-shaped member 570 (front frame 11) and can pivot in response to the movement of the connecting portion 603. Therefore, the connecting portion 603 can move not only in one direction but also in multiple directions (in the arc direction about the pivot shaft 705 and the direction D3 in this embodiment). Therefore, it is possible to design the movement directions of the connecting portion 603 and the connecting portion 203 without being limited to the biasing direction (expansion / contraction direction) of the elastic member 600. In this embodiment, a configuration in which the elastic member 600 pivots in response to the movement of the connecting portion 603 has been illustrated, but the present invention is not limited to this configuration. For example, if a through-hole that changes the distance between the connecting portion 603 and the rotation axis 705 of the rotating connecting member 700 is provided in the rotating connecting member 700, such as the sliding portion 720 (through-hole) of this embodiment, and a configuration is adopted in which the rotating connecting member 700 is permitted to rotate, the rotation of the elastic member 600 is not essential. Also, for example, a configuration in which the elastic member 600 follows the movement of the connecting portion 603 by providing a mechanism that moves the elastic member 600 in parallel in the left-right direction in accordance with the movement of the connecting portion 603 may be adopted.

[0045] [1-3. Action of External Force Applied to Working Unit 40 on Relief Mechanism Unit 50] If an obstacle collides with working unit 40 from the front in the state shown in FIG. 3 and an external force is applied to working unit 40, working unit 40 will attempt to rotate about pivot point 25 (see FIG. 2) of the pivotally connected offset link, and second link arm 22 will be pushed toward connecting portion 203. The force pushing connecting portion 203 is converted by pivot connecting member 700 into rotational power of pivot connecting member 700. Specifically, as shown in FIGS. 3(B) and 4, the force F1 with which second link arm 22 pushes connecting portion 203 is converted by pivot connecting member 700 into a component (F2) in the tangential direction of a circle centered on pivot axis 705. This F2 is the power that causes connecting portion 203 to rotate pivot connecting member 700. Therefore, the rotational power is derived from the magnitude of the force with which the second link arm 22 pushes the connecting portion 203 (the magnitude of F1) and the angle between the direction in which the second link arm 22 pushes the connecting portion 203 (the direction of F1) and the tangent direction at the connecting portion 203 (the direction of F2).

[0046] FIG. 5, like FIG. 3, is an explanatory diagram showing the offset work machine according to one embodiment of the present invention in a state before the working unit comes into contact with an obstacle. The state of the offset work machine 100 shown in FIG. 5 is a state in which the offset amount is smaller than that shown in FIG. 3. Comparing FIG. 3B with FIG. 5B, there is no difference in the state of the escape mechanism 50, but the longitudinal direction of the second link arm 22 is different. Specifically, when the offset amount is small (FIG. 5), the angle between the longitudinal direction of the second link arm 22 and the D1 direction is smaller than when the offset amount is large (FIG. 3). As a result, the angle between the F1' direction and the F2' direction when the offset amount is small (FIG. 5) is smaller than the angle between the F1 direction and the F2 direction when the offset amount is large (FIG. 3).

[0047] Here, the magnitude of the force with which the second link arm 22 pushes the connecting portion 203 will be described for each of the cases shown in FIGS. 3 and 5. In the following description, a case where an external force FX is applied to the end of the working unit 40 in the D2 direction will be described. The force pushing the connecting portion 203 is determined based on the product of the external force FX and the horizontal distance in the D2 direction between the rotation fulcrum of the power transmission unit 30 on the front frame 11 (a position corresponding to the output shaft 16 in FIGS. 1 and 2) and the position where the external force FX is applied. That is, in the case of FIG. 3, the force pushing the connecting portion 203 is determined based on the product of the external force FX and the horizontal distance L1. In the case of FIG. 5, the force pushing the connecting portion 203 is determined based on the product of the external force FX and the horizontal distance L2. Because L2 is smaller than L1, when the external force FX is the same, the force F1' in the state shown in FIG. 5 is smaller than the force F1 in the state shown in FIG. 3. That is, when the external force FX is the same, as the offset amount decreases, the rotational power of the pivotal connecting member 700 by the connecting portion 203 decreases.

[0048] If the relief mechanism 50 according to this embodiment were not provided with the above-described function, the smaller the offset amount, the more difficult it would be for the relief mechanism 50 to function. In other words, if the offset amount is small, the relief mechanism 50 may not function even if a very large external force is applied to the working unit 40. In such a case, the offset mechanism 20, the power transmission unit 30, and the working unit 40 may be damaged. Even if these components are not damaged, when the same magnitude of external force is applied to the working unit 40, the relief mechanism 50 may or may not function depending on the offset amount. In other words, in this case, stable operation of the relief mechanism 50 cannot be obtained.

[0049] On the other hand, in this embodiment, because the escape mechanism 50 has the above function, even if F1' in Fig. 5 is smaller than F1 in Fig. 3, the angle between the directions of F1' and F2' is smaller than the angle between the directions of F1 and F2, so that F2' converted from F1' can be made to be approximately the same size as F2 converted from F1. In other words, the external force FX required for the escape mechanism 50 in this embodiment to function can be made uniform regardless of the offset amount.

[0050] [1-4. Operation of the escape mechanism 50] 3, when no external force is applied to working unit 40, connecting portion 603 is biased toward first end 511 by elastic member 600. When external force FX is applied to working unit 40 in this state, the force of second link arm 22 pressing connecting portion 203 generates rotational power of pivotal connecting member 700, and power is applied to connecting portion 603 to pivot connecting portion 603 in a direction away from first end 511.

[0051] 6, when the power applied to connecting portion 603 exceeds the biasing force with which elastic member 600 biases connecting portion 603 toward first end 511, connecting portion 203 moves forward within movement limiting portion 502. As connecting portion 203 moves forward, rotating connecting member 700 rotates (counterclockwise) around rotation axis 705, and connecting portion 603 moves backward (from first end 511, via bent portion 515, to second end 521) within movement limiting portion 503 while contracting elastic member 600. Because movement limiting portion 502 is arc-shaped, the distance between rotation axis 705 and connecting portion 203 remains the same before and after the movement of connecting portion 203.

[0052] In movement limiting portion 503, region 586 is arc-shaped, so the distance between pivot shaft 705 and connecting portion 603 does not change while connecting portion 603 moves from first end 511 to bent portion 515, but because region 585 extends in direction D3, the distance between pivot shaft 705 and connecting portion 603 gradually decreases as connecting portion 603 moves from bent portion 515 toward second end 521. At this time, connecting portion 603 approaches pivot shaft 705 while sliding on sliding portion 720.

[0053] In the present embodiment, a configuration has been exemplified in which the connecting portion 603 moves within the movement limiting portion 503 while contracting the elastic member 600 as the connecting portion 603 moves, but the present invention is not limited to this configuration. For example, the connecting portion 603 may move within the movement limiting portion 503 while stretching the elastic member 600 as the connecting portion 603 moves.

[0054] 7 and 8, the movements of connecting portion 203 and connecting portion 603 during the change from the state in Fig. 3 to the state in Fig. 6, and the change in the magnitude of the power applied from rotating connecting member 700 to connecting portion 603 will be described. Similar to Fig. 4, Fig. 7 and Fig. 8 are exploded views of the flat plate-shaped member and the rotating connecting member in an offset work machine according to one embodiment of the present invention.

[0055] FIG. 7 is a diagram showing the connecting portion 603 moving through an arc-shaped region 586 centered on the pivot shaft 705 (insertion hole 505). The connecting portion 603 moves away from the first end 511 and reaches the inner wall of the movement limiting portion 503 on the rear side in region 585. During this movement, the connecting portion 603 moves through the arc-shaped region 585. Furthermore, since the sliding portion 720 extends toward the pivot shaft 705 (the pivot shaft 705 is provided on an extension line extending from the sliding portion 720 in the D4 direction), the direction in which the sliding portion 720 pushes the connecting portion 603 during the above movement is the normal direction at the point of contact between the inner wall on the front side of the sliding portion 720 and the connecting portion 603. Therefore, while the connecting portion 603 is being pushed by the sliding portion 720 and moving through region 585, the connecting portion 603 does not move within the sliding portion 720. In other words, while connecting portion 603 is moving in region 585, the angle formed between direction D4, which is the longitudinal direction of sliding portion 720, and the direction in which connecting portion 603 can move in region 585 (the direction along the arc centered on rotation shaft 705) is 90°. However, this angle is not limited to 90°.

[0056] 7, the ratio of the distance L3 between the pivot shaft 705 and the connecting portion 203 to the distance L4 between the pivot shaft 705 and the connecting portion 603 remains constant. Therefore, when the same magnitude of force is applied to the connecting portion 203, the magnitude of the power applied from the pivotal connecting member 700 to the connecting portion 603 remains constant.

[0057] 8 is a diagram showing the coupling portion 603 moving in the region 586 extending in the direction D3. After the coupling portion 603 reaches the inner wall on the rear side of the movement restricting portion 503, the pivotable coupling member 700 further pivots (counterclockwise) about the pivot axis 705. Because the angle between the directions D3 and D4 is less than 90°, the coupling portion 603 slides on the inner wall and moves toward the second end portion 521. As the coupling portion 603 moves along the second sliding portion in the direction D3, the distance between the coupling portion 603 and the pivot axis 705 becomes shorter. During this time, the coupling portion 603 continues to be pressed by the inner wall on the front side of the sliding portion 720, and therefore the coupling portion 603 approaches the pivot axis 705 while sliding on the inner wall on the front side of the sliding portion 720.

[0058] Unlike this embodiment, if the angle between the D4 direction and the direction in which the connecting part 603 can move while the connecting part 603 is moving in the region 585 is less than 90°, the angle may be larger than the angle between the D3 direction and the D4 direction while the connecting part 603 is moving in the region 586.

[0059] A portion of the inner wall of sliding portion 720 on which connecting portion 603 slides may be referred to as a "first sliding portion 591." A portion of the inner wall in region 585 of movement restricting portion 503 on which connecting portion 603 slides may be referred to as a "second sliding portion 592." Using these expressions, the above operation can be restated as follows: connecting portion 603 slides on first sliding portion 591 and is pushed rearward by first sliding portion 591, thereby sliding on second sliding portion 592 in direction D3 and approaching rotation axis 705.

[0060] 8, the ratio of distance L3 to distance L4 changes. Specifically, as pivotal link 700 pivots (counterclockwise) about pivot axis 705 and link 603 moves on second sliding portion 592 toward second end 521, the ratio of L4 to L3 decreases. As a result, when the same magnitude of force is applied to link 203, the magnitude of the power applied from pivotal link 700 to link 603 gradually increases.

[0061] Here, the greater the degree of elastic deformation of the elastic member 600, the stronger the restoring force. If the escape mechanism 50 according to this embodiment were not provided with the above-described function (the function of decreasing the ratio of L4 to L3 as the pivotal coupling member 700 pivots), when the coupling portion 603 moves away from the first end 511 and the amount of deformation of the elastic member 600 increases, the force required to pivot the pivotal coupling member 700 (the rotational power of the coupling portion 203) would increase. As a result, the offset mechanism 20, the power transmission unit 30, the working unit 40, and the escape mechanism 50 may be damaged.

[0062] On the other hand, in this embodiment, as the pivotal connecting member 700 rotates and the connecting portion 603 becomes farther away from the first end 511, the magnitude of the force applied from the pivotal connecting member 700 to the connecting portion 603 gradually increases, thereby preventing the occurrence of the above-mentioned problems.

[0063] Although the present invention has been described above with reference to the drawings, the present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the present invention. For example, if a person skilled in the art appropriately adds, deletes, or modifies components based on the embodiments, such modifications are also included in the scope of the present invention as long as they incorporate the gist of the present invention. Furthermore, the above-described embodiments can be appropriately combined as long as there are no mutual contradictions, and technical matters common to the embodiments are included in each embodiment even if not explicitly stated.

[0064] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0065] 10: Mounting portion, 11: Front frame, 13: Lower link coupling portion, 14: Input shaft, 15: Power transmission means, 16: Output shaft, 20: Offset mechanism portion, 21: First link arm, 22: Second link arm, 23: Third link arm, 24: Telescopic member, 25: Pivot fulcrum, 30: Power transmission portion, 31: Driving sprocket, 32: Driven sprocket, 33: Roller chain, 40: Working portion, 41: Working rotor, 41a: Claw shaft, 41b: Cutting blade, 42: Cutting blade drive portion, 50: Escape mechanism portion, 100: Offset work machine, 201: Connection portion, 203: Linking portion, 502, 503: Movement limiting portion, 505: Insertion hole, 511: First end portion, 515: Bending portion, 521: Second end portion, 570: Flat plate-shaped member, 585, 586: Area, 590: Rotation center, 591: First sliding portion, 592: Second sliding portion, 600: Elastic member, 603: Connecting portion, 610: Rotation shaft member, 620: Contact member, 630: Shaft member, 631: End portion, 700: Rotation connecting member, 705: Rotation shaft, 710: Connection portion, 720: Sliding portion

Claims

1. a working unit that receives power from the traveling machine body and performs agricultural work; an escape mechanism for causing the working unit to move away when an external force equal to or greater than a predetermined force acts on the working unit; an offset mechanism having an arm extending from the working unit toward the relief mechanism, and offsetting the working unit in the left-right direction; a first connecting portion that connects the arm portion and the escape mechanism portion, The escape mechanism portion is An elastic member; a rotational connecting member connected to the first connecting portion and rotatable about a rotation axis; a second connecting portion that connects the elastic member and the pivot connecting member, the pivotal connecting member is connected to the arm portion at the first connecting portion, the first connecting portion is rotatable about the rotation axis; the second connecting portion is movable in accordance with the rotation of the rotary connecting member, the elastic member biases the second connecting portion in a direction that inhibits the rotation of the rotation connecting member when an external force is applied to the working portion, An offset work machine configured so that when the external force acts on the working part, the angle between the direction in which the arm part acts on the first connecting part and the direction in which the first connecting part attempts to move as the pivotal connecting member rotates due to the external force is smaller when the amount of offset movement is small than when it is large.

2. the offset mechanism includes a parallel link mechanism, the arm portion constitutes a link of the parallel link mechanism, The offset work machine according to claim 1 , wherein the first connecting portion constitutes a pair (joint) of a part of the parallel link mechanism.

3. the rotational connecting member has a first sliding portion extending in a first direction in which a distance from the rotational shaft changes; The offset work machine according to claim 1 or 2, wherein the second connecting portion approaches the rotation shaft by sliding on the first sliding portion in the first direction.

4. the escape mechanism further includes a first member including a second sliding portion extending in a second direction different from the first direction, the second direction being a direction in which a distance from the rotation shaft changes; the second connecting portion slides on the first sliding portion while sliding on the second sliding portion in the second direction, thereby approaching the rotation axis; The offset work machine according to claim 3 , wherein the elastic member extends or contracts while rotating relative to the frame in response to movement of the second connecting portion.

5. the first member includes a second region continuous with a first region in which the second sliding portion is provided, the second region is a region in which the second connecting portion is movable in a third direction different from the second direction, 5. The offset work machine according to claim 4, wherein an angle formed between the third direction and the first direction when the second connecting portion is positioned in the second region is larger than an angle formed between the second direction and the first direction when the second connecting portion is positioned in the first region.

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