JP7510176B2 - Grass cutting equipment - Google Patents

Description

The present invention relates to a grass cutting device that is attached to a traveling vehicle such as a tractor. In particular, it relates to a grass cutting device that can follow the undulations of the ground.

Patent document 1 discloses an example of a work machine in which a working unit is attached to the front end of a boom or arm that can swing up and down. This invention is provided with a control device that uses a sensor, which is a detection unit that detects the distance to the ground, to keep the working unit, the grass cutting device, within a set height range. This allows the working unit to follow the undulations of the ground and prevents it from coming into contact with the ground.

Japanese Utility Model Application Publication No. 58-194620

However, if the sensor is installed on the side panel of the grass cutting device as described in Patent Document 1, it may be damaged by flying debris or obstacles passing by the side, so it is preferable to install it away from the ground or in a position where it is less likely to hit obstacles.

Therefore, the present invention was made with the above problem in mind, and aims to provide a grass cutting device that can detect undulations regardless of the work location and eliminate the inconvenience of obstacles.

In order to achieve the above object, one aspect of the present invention is a grass cutting device that includes a boom device having at least one boom and that is arranged so that the boom can be rotated up and down; a frame that is arranged at the tip of the boom device and extends forward from the tip of the boom device in the direction of travel; a work arm that is supported at one end so that it can be rotated substantially horizontally on a fulcrum shaft arranged near a fulcrum tube arranged on the frame and has a working section at the other end that can perform ground work; a skid that has a support shaft arranged coaxially with the fulcrum tube and is arranged so that it can move up and down relative to the fulcrum tube by the support shaft and is arranged at the lower end of the support shaft and can come into contact with a work surface; a switch that can be operated via the support shaft that moves up and down with the up and down movement of the skid; and a control unit that causes the switch to rotate the boom upward when it detects upward movement of the skid and releases the boom rotation when it detects downward movement of the skid.

This invention provides a grass cutting device that can detect undulations regardless of the work location and eliminate the inconvenience of obstacles.

FIG. 2 is a front view of the grass cutting device according to the embodiment, as viewed from the front in the traveling direction. FIG. 2 is a side view of the grass mowing device showing the embodiment, viewed from the left side in the traveling direction. 1 is a plan view of the grass cutting device according to an embodiment, showing a state in which the working unit is located in a first working area. FIG. FIG. 2 is a bottom view of the grass cutting device according to the embodiment, showing a state in which the working unit is located in a first working area. FIG. 2 is a side view showing a cross section of a main part of the grass cutting device according to the embodiment. FIG. 2 is a side view in cross section of a main part of the grass mowing device showing the embodiment, with the right side shown in the figure being the forward direction in the traveling direction. FIG. 2 shows a rear view of an example of a grass cutting device attached to a boom device provided on a traveling body. FIG. 2 is a fluid circuit diagram of the grass cutting device showing the embodiment. 1 is a control block diagram of a grass cutting device showing an embodiment. FIG. FIG. 4 is a control flow diagram of the grass cutting device showing the embodiment.

One embodiment of the present invention will be described with reference to the drawings. In the description, the left side shown in FIG. 1 is expressed as the right side in the direction of travel, the right side as the left side in the direction of travel, the left side shown in FIG. 2 as the forward side in the direction of travel, and the right side as the rear side in the direction of travel. The left side shown in FIG. 3 to FIG. 5 is described as the forward side in the direction of travel, and the right side shown in FIG. 6 is described as the forward side in the direction of travel. In addition, in the description, the upward direction refers to the direction away from the ground side, which is the work surface, and the downward direction refers to the direction approaching the ground side. In the description of the drawings, the same or similar parts are given the same or similar reference numerals, and the description thereof may be omitted. In addition, the drawings used in the description are schematic, and the relationship between the dimensions of each part may differ from the actual ones. In addition, the technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

As shown in FIG. 7, the grass cutting device 1 is attached to a traveling machine body T consisting of a tractor or the like by a boom device A, which is an attachment frame consisting of a single or multiple booms. FIG. 7 shows an example in which the grass cutting device 1 is attached to a boom device A that can be freely extended or flexed by a cylinder or the like consisting of multiple boom devices A attached to the rear of the traveling machine body T. By rotating the boom of the illustrated boom device A up and down around a rotation axis as a fulcrum, it is possible to move the grass cutting device 1 up and down relative to the traveling machine body T.

The grass cutting device 1 shown in Figures 1 to 4 is attached to the boom device A by the mounting part 10. The mounting part 10 is attached to the frame 2, which extends forward in the direction of travel. The working arm 50 is located below the frame 2 and is capable of rotating horizontally, and has a working part 51 attached to the tip of the rotating radial direction. The working part 51 has multiple cutting blades 511 that rotate horizontally, and the grass cutting work is performed by rotating the cutting blades 511. Since the working part 51 is freely rotatable in the horizontal direction by the working arm 50, it can pass obstacles that move relatively from the front side while rotating. Since the working part 51 is arranged to protrude from the mounting part 10 by the frame 2, it can work even in places where there are obstacles covering the upper part of the working part 51. A skid 73 that comes into contact with the ground, which is the work surface, is provided below the front end of the frame 2, and the working part 51 can be maintained at a constant height. Furthermore, a skid 73 is positioned in front of the working unit 51 to further improve the maintenance of the working unit 51's height.

The mounting part 10 can be fixed integrally to the boom device A by fitting it to the tip of the boom device A, and can be released from the boom device A by releasing this fixation. In other words, the grass cutting device 1 can be freely attached and detached from the boom device A. In the embodiment, the boom device A is fixed to the top of the mounting part 10, but there is no limitation on the fixed position. In addition, a rolling fulcrum part A1, which is an axis facing the direction of travel, is provided at the tip of the boom device A, and the grass cutting device 1 can be rotated left and right.

The rear end of the frame 2 is fixed to one end of the mounting part 10, which is on the left side in the traveling direction. In this embodiment, the frame 2 is composed of a first frame 20 that is long forward, and a second frame 30 that is connected to the front end of the first frame 20 by a bending shaft 40 and can rotate horizontally relative to the first frame 20. The first frame 20 is a long member and is arranged so that its long dimension protrudes forward. A holder part 22 is provided at the front end of the first frame 20, and a bending shaft 40, which is a vertical axis, is provided on this holder part 22. The rear end of the second frame 30 is connected to this bending shaft 40 so that it can rotate horizontally.

The second frame 30 is a long member, and is positioned so that its long dimension protrudes forward. In the embodiment, the second frame 30 is positioned so that its long dimension is inclined relative to the first frame 20 in a plan view. By providing the second frame 30 with the ability to rotate around the bending axis 40 as a fulcrum, when a load is applied to the second frame 30 rearward in the traveling direction due to a collision with an obstacle or the like, the second frame 30 rotates rearward, preventing damage to the frame 2. Note that, in the embodiment, the frame 2 is provided with the first frame 20 and the second frame 30 bendable, but they may be integrated and unbendable.

The fulcrum shaft 31 is provided below the front end of the second frame 30, which is the front end of the frame 2. The fulcrum shaft 31 is provided near the middle of the fulcrum tube 71, which protrudes downward from the front end of the second frame 30. The fulcrum tube 71 is a member for supporting the support shaft 72 of the skid 73. The fulcrum tube 71, skid 73, and support shaft 72 will be described later.

The fulcrum shaft 31 is a vertical shaft and is provided below the front end of the frame 2. In the present embodiment, it is located behind the middle part of the fulcrum tube 71 that hangs down from the front end of the frame 2. One end of the working arm 50 is attached to the fulcrum shaft 31. The working arm 50 can freely rotate horizontally around the fulcrum shaft 31.

A working unit 51 is provided on the other end of the working arm 50, which is the side radially away from the axis of the fulcrum shaft 31. The working unit 51 is a working part capable of cutting grass growing on the ground. The working unit 51 includes a cutting blade 511, a motor 512, and a cover member 513. The motor 512 is provided on the other end of the working arm 50, and drives the cutting blade 511 disposed below it to rotate. There are multiple cutting blades 511, which are freely rotatable in the horizontal direction around the motor 512 as an axis and rotate by receiving the rotational power of the motor 511. The rotating cutting blades 511 can cut grass present on the work surface.

The working arm 50 is provided with a cover member 513. The cover member 513 is a teardrop-shaped member in a plan view, with the teardrop-shaped protrusion facing the fulcrum shaft 31. The cover member 513 is positioned above the cutting blade 511 to prevent objects such as grass clippings scattered by the cutting blade 511 from scattering upward. In the case of this embodiment, the other end of the working arm 50 is positioned rearward of the fulcrum shaft 31 in a plan view, and the motor 512 that serves as the rotation drive shaft for the cutting blade 511 is positioned to the side of the frame 2.

The working arm 50 can rotate horizontally around the fulcrum shaft 31 to position the working unit 51 shown in FIG. 3 in either a first working area B on the left side of the traveling direction, or a second working area C on the right side of the traveling direction, which are divided along the front-to-rear longitudinal direction passing through the fulcrum shaft 31. The working unit 51 shown by the solid line in FIG. 3 shows the state in which it is positioned in the first working area B, and the working unit 51 shown by the two-dot chain line shows the state in which it is positioned in the second working area. Grass-cutting work is performed by the working unit 51 positioned in each area.

The fulcrum shaft 31 is provided with a switching piece 55 that is separate from the working arm 50 and can rotate around the same axis as the working arm 50. The switching piece 55 is provided separately from the working arm 50 and rotates around the fulcrum shaft 31 independently of the working arm 50. An arc-shaped long hole 551 is provided at one end of the switching piece 55. In the embodiment, the long hole 551 is provided on the first working area B side, which is the one end side. The rotation restricting body 52 is passed through the long hole 551. The center of the arc of the arc-shaped long hole 551 is provided coaxially with the fulcrum shaft 31, so the switching piece 55 can freely rotate within the long hole 551.

The rotation restricting body 52 is a rod-shaped member that is long in the vertical direction and is placed near the fulcrum shaft 31 and passes through the long hole 551. Furthermore, the rotation restricting body 52 comes into contact with the work frame 51, thereby restricting the rotation angle of the work frame 51 in the forward direction in each of the first work area B and the second work area C.

A rod-shaped guide rod 57 is rotatably arranged at the other end of the switching piece 55. The guide rod 57 is arranged to span a guide rod fulcrum 571 provided at the other end of the switching piece 55 and a guide rod holding part 572 provided on the other end side of the working arm 50. As shown in FIG. 3, when the working part 51 is positioned in the first working area B, the guide rod fulcrum 571 is provided on the second working area C side. The guide rod holding part 572 is located in the first working area B and holds the guide rod 57 slidably in the axial direction, so as not to impede the rotational movement of the working arm 50.

A biasing body 56 is arranged on the outer periphery of the guide rod 57 to bias the working arm 50 towards either the first working area B or the second working area C. In this embodiment, a compression spring is used as the biasing body 56. The guide rod 57 serves to guide the biasing body 56 so that it does not shift. A biasing body regulating portion 573 is fixed to the guide rod fulcrum portion 571 side of the guide rod 57. The biasing body 56 biases the working arm 50 by expanding and contracting between the biasing body regulating portion 573 and the guide rod holding portion 572. The biasing body 56 biases the working unit 51 and the working arm 50 forward in the direction of travel.

The action of the switching piece 55 will now be described. The switching piece 55 rotates around the fulcrum shaft 31, changing the biasing direction of the biasing body 56 and pushing the working arm 50 towards either the first working area B or the second working area C. The working arm 50 located in the first working area B or the second working area C is pushed by the biasing body 56 to rotate until the working arm 50 comes into contact with the rotation restricting body 52, and the rotation is restricted at the position where the working arm 50 comes into contact with the rotation restricting body 52.

3 shows the state in which the working arm 50 and the working unit 51 are located in the first working area B. The arrow extending in an arc in FIG. 3 indicates the first rotation direction D and the second pivot direction E, which are the rotation directions of the working arm 50, the working unit 51, and the switching piece 55 around the fulcrum shaft 31. When the working unit 51 is located in the first working area B, the guide rod fulcrum part 571 of the switching piece 55, which is located behind the fulcrum shaft 31 and on the second working area C side, is pushed by the biasing body 56 to rotate the switching piece 55 in the second pivot direction E, which is a left rotation direction in a plan view. The switching piece 55 rotates in the second pivot direction E until the pivot restricting body 52 contacts one end of the long hole 551, and after the contact, the pivot of the switching piece 55 is restricted. The biasing body 56 continues to bias the switching piece 55, whose rotation is restricted, in the second rotation direction E, and by pressing the guide rod holding portion 572, rotates the working arm 50 in the first rotation direction D, which is a right rotation direction in a plan view, until the working arm 50 contacts the rotation restricting body 52. In other words, the working arm 50 and the working unit 51 are biased forward in the direction of travel in the first working area. In the first working area B, the position where the working arm 50 contacts the rotation restricting body 52 is called the return position in the first working area B.

In this way, the working unit 51 located in the first working area B can be deployed away from the side of the frame 2 by being biased in the first pivot direction D by the switching piece 55 and the biasing body 56, and can be positioned at the return position in the first working area B. Also, when the working unit 51 and the working arm 50 are pushed backward by an external force, they pivot in the second pivot direction E in accordance with the external force. At this time, the distance between the guide rod holding part 572 and the biasing body regulating part 573 is shortened, and the biasing body 56 is compressed. The compressed biasing body 56 is in a state in which the repulsive force is increased. Since the guide rod fulcrum part 571 is located on the second working area C side of the line segment connecting the fulcrum shaft 31 and the guide rod holding part 572, when the external force is removed, the working arm 50, which has been biased by the biasing body 56, returns to the return position in the first working area B. In this case, an external force in actual work refers to an obstacle higher than the working unit, such as a pillar, and when this obstacle collides with the working unit, the working arm 50 and the working unit 51 rotate backward within the first working area B. Then, when the external force is removed, the working arm 50 and the working unit 51 return to their return positions.

As shown by the two-dot chain line in FIG. 3, the working arm 50 and the working unit 51 can be switched from the first working area B to the second working area C by the switching piece 55 and the biasing body 56. When switching, the working arm 50 or the working unit 51 located in the first working area B is rotated toward the second rotation direction E. If the working arm 50 continues to rotate in the second rotation direction E, the working arm 50 and the working unit 51 will eventually be located on the second working area C side. If the working arm 50 continues to rotate further, the fulcrum shaft 31, the guide rod fulcrum part 571, and the guide rod holding part 572 will be arranged on a straight line in a plan view. If the working arm 50 continues to rotate further, the guide rod fulcrum part 571 will be located on the first working area B side of the virtual line segment connecting the fulcrum shaft 31 and the guide rod holding part 572, so that the switching piece 55 will be rotated in the first rotation direction D by the biasing body 56. The switching piece 55 rotates until the rotation restricting body 52 contacts the other end of the long hole 551, and then the rotation in the first rotation direction D is restricted by the rotation restricting body 52. The working arm 50 and the working part 51 are then positioned in the second working area C, and are urged by the biasing body 56 toward the forward direction of travel, which is the second rotation direction E. The biasing body 56 continues to urge the switching piece 55, whose rotation is restricted, in the first rotation direction D, and rotates the working arm 50 in the second rotation direction E, which is a left rotation direction in a plan view, until the working arm 50 contacts the rotation restricting body 52. This position is called the return position in the second working area C.

The working unit 51 located in the second working area C can be urged in the second pivot direction E by the switching piece 55 and the biasing body 56, and deployed away from the side of the frame 2 to be positioned in a return position in the second working area C. Furthermore, when the working unit 51 and working arm 50 are pushed rearward by an external force such as an obstacle, they pivot in the first pivot direction D in accordance with the external force, but return to their return position in the second working area C when the external force is removed. The procedure for moving the working unit 51 located in the second working area C to the first working area B is similar to that described above, so a description of this will be omitted.

By using the switching piece 55, one working unit 51 can be deployed to either the first working area B or the second working area C, and the direction of the biasing force of the biasing body 56 can be changed so that it faces the return position corresponding to each deployment position.

A skid, called a working skid 58, is provided on the radial side of the rotating cutting blade 511. The working skid 58 is a rod-shaped sled member formed from a rod-shaped member, and multiple working skids 58 are provided around the side of the cutting blade 511. In the embodiment described, the working skids 58 are provided at two locations around the side of the cutting blade 511, symmetrical with respect to the longitudinal direction of the working arm 50. In the description, one working skid 58 is referred to as the first working skid 58a, and the other as the second working skid 58b.

In plan and bottom views, the working section skid 58 is curved to follow the circumferential direction of the blade 511. In side view, the working section skid 58 includes an inclined portion 581 that is connected to the lower portion of the cover member 513 and inclines rearward as it goes downward, a grounding portion 582 that extends horizontally from the lower end of the inclined portion 581, and a rising portion 583 that rises from the rear end of the grounding portion 582 and connects its upper portion to the lower portion of the cover member 513. The illustrated working section skid 58 is formed of a rod-shaped member, but is not limited to this and may be formed of a plate-shaped member or the like, and may be installed in two or more locations.

The first working skid 58a, which is one of the working skids 58 in the first working area B, will be described. In the first working area B, the first working skid 58a is arranged at a position furthest in the width direction of the traveling direction, based on the fulcrum shaft 31. In a plan view, the inclined portion 581a of the first working skid 58a curves from the front side of the cutting blade 511 to the rear while following the rotation direction of the cutting blade 511. The ground contact portion 582a of the first working skid 58a, which is continuous with the inclined portion 581a, is elongated, and the elongated direction faces the traveling direction. A rising portion 583a is arranged from the rear end of the ground contact portion 582a and is connected to the cover member 513.

The inclined portion 581a of the first working unit skid 58a guides the undulating ground surface, which is the working surface that moves relatively from the front as the mowing work progresses, to the ground contact portion 582a at the rear. When guiding, the inclination of the inclined portion 581a causes the mowing device 1 to gradually rise with a rolling motion, with the rolling fulcrum portion A1 at the tip of the boom device A as its axis. In other words, the cutting blade 511 is also lifted up along the undulating ground surface. The ground surface undulations are maintained by the ground contact portion 582a touching the ground and then sliding along the ground in the longitudinal direction, thereby maintaining the relative height of the cutting blade 511 and the undulating ground surface.

When the undulations of the ground reach the rising part 583a, which is the rear end of the ground contact part 582a, there is nothing to support the working part 51, so the working part 51 descends again along the undulations of the ground, with the rolling fulcrum part A1 as its axis. This configuration prevents the undulations of the ground from coming into contact with the rotating cutting blade 511. The inclined part 581a and the ground contact part 582a are disposed at the farthest position from the rolling fulcrum part A1 and the fulcrum axis 31 in a plan view. The first working part skid 58a guides the undulations of the ground at the outermost part of the working width of the cutting blade 511, thereby ensuring the cutting height of the cutting blade 511 and protecting the cutting blade 511 from contact with the ground. In addition, by disposing the ground contact part 581a at the outermost part of the working width, the ground contact part 582a can be separated from the rolling fulcrum part A1, and the rolling operation of the working part 51 can be performed more reliably. In other words, the force required for the turning operation by the rolling fulcrum part A1 is reduced, allowing for smooth turning. This prevents the inclined portion 581a and the ground contact portion 582a from digging into the ground.

As described above, the working unit 51 may be moved up and down not by raising and lowering the rolling fulcrum A1, but by bending the multiple booms of the boom device.

The second working section skid 58b, which is the other working section skid 58 in the first working area B, will now be described. The inclined portion 581b of the second working section skid 58b is located on the fulcrum axis 31 side in the width direction of the traveling direction relative to the inclined portion 581a of the first working section skid 58a, and is located slightly rearward. The inclined portion 581b relative to the inclined portion 581a does not interfere with the rolling motion caused by the ups and downs of the inclined portion 581a and ground contact portion 582a, which are the skids on one side, and does not get stuck on the ground.

The grounding portion 582b following the inclined portion 581b is located on the rear side of the cutting blade 511, and its longitudinal direction is arranged to intersect with the direction of travel. In other words, the longitudinal direction of the grounding portion 582b of the second working unit skid 58b is arranged to intersect with the longitudinal direction of the grounding portion 582a of the first working unit skid 58a. In addition, the grounding portion 582b is located at the rear end of the working unit 51. By arranging it in this way, the first working unit skid 58a receives the undulations that move relatively from the front to the working unit 51 before the second working unit skid 58b. In other words, the second working unit skid 58b in the first working area B does not interfere with the rolling motion of the working unit 51.

The other second working unit skid 58b in the first working area B is arranged so that the longitudinal direction of the grounding portion 582b intersects with the direction of travel. In other words, the longitudinal direction of the grounding portion 582b is oriented substantially in the direction of rotation of the working unit 51 around the fulcrum shaft 31. Therefore, the second working unit skid 58b does not interfere with the horizontal rotation of the working unit 51 caused by the rotation of the working arm 50 around the fulcrum shaft 31.

The grass cutting device 1 is configured so that the working unit 51 can be protruded to either the left or right in the direction of travel relative to the fulcrum shaft 31 to perform work. In other words, the working unit 51 can be positioned in the second working area C to perform work. When the working unit 51 is positioned in the second working area C, the second working unit skid 58b is positioned in a position farthest from the rolling fulcrum A1 and the fulcrum shaft 31 in a plan view. In addition, the first working unit skid 58a, which is one of the working unit skids 58 in the second working area C, has its inclined portion 581a positioned on the fulcrum shaft 31 side in the width direction of the direction of travel and slightly rearward relative to the inclined portion 581b of the second working unit skid 58b.

The action and effect of the first working section skid 58a and the second working section skid 58b in the second working area C is opposite to the action and effect of the first working section skid 58a and the second working section skid 58b in the first working area B. This explanation is omitted as it is similar to the explanation above.

When the working unit 51 is positioned in the first working area B, the grounding portion 582a of the first working unit skid 58a faces the direction of travel, and when the working unit 51 is positioned in the second working area C, the grounding portion 582b of the second working unit skid 58b faces the direction of travel. In other words, the longitudinal direction of at least one of the grounding portions 582 of the multiple working unit skids 58 faces the direction of travel when the working unit 51 is positioned in either the first working area B or the second working area C. With this configuration, the working unit 51 can smoothly move up and down by rolling to follow the ground, and the working unit 51 can rotate horizontally around the fulcrum axis 31 to pass obstacles that move relatively from the front of the grass cutting device 1 and collide with the working unit 51.

The illustrated working section skids 58 are shown arranged in two locations along the circumferential direction of the blade 511, but three or more locations are also acceptable. In this case, it is sufficient that the longitudinal direction of the ground contact portion 582 of at least one working section skid 58 faces the direction of travel.

The area surrounded by the cover member 513, the inclined portion 581, the grounding portion 582, and the rising portion 583 forms a passage space S through which objects can pass. The passage space S does not block the path of objects, such as grass clippings that scatter sideways from the cutting blade 511, so objects do not accumulate between the working section skid 58 and the cutting blade 511. In other words, the cutting blade 511 can work without coming into contact with foreign objects, so it is possible to cut grass, which is the object to be cut that moves relatively from the front in the direction of travel, without putting a load on the cutting blade 511 or the motor 512 that rotates it.

A bowl-shaped grounding body 59 is provided under the working unit 51. The bowl-shaped grounding body 59 is provided coaxially with the rotation axis of the cutting blade 511. The bowl-shaped grounding body 59 is attached so that it can rotate freely independent of the rotation of the cutting blade, so that even when the bowl-shaped grounding body touches the ground, it remains stationary and prevents the cutting blade from coming into contact with undulating ground surfaces, etc.

The grounding point s1 at the bottom of the bowl-shaped grounding body is positioned above the grounding point 582s at the bottom of the grounding part 582 of the working part skid 58. The part of the lower part of the working part 51 that can come into contact with the ground is configured in two stages, the working part skid 58 and the bowl-shaped grounding body 59.

The working part skid 58 guides the majority of rough undulations, causing the working part 51 to move up and down, while the bowl-shaped ground contact body 59 captures ground undulations that the working part skid 58 cannot fully guide, causing the working part 51 to move up and down. If there are undulations in the ground approaching below the cutting blade 511 as the mower advances, the bowl-shaped ground contact body 59 comes into contact with the undulations in the ground, pushing up the grass cutting device 1 via the working part 51. The grass cutting device 1 then moves up and down at the rolling fulcrum A1 near the mounting part 10 and the boom device A.

A vertically long support shaft 72 that supports a skid 73 is inserted coaxially into a fulcrum tube 71 that is disposed downward from the front end of the frame 2. The support shaft 72 is provided so that it can move up and down relative to the fulcrum tube 71. The skid 73 is fixed to the lower part of the support shaft 72. In other words, the skid 73 is provided so that it can move up and down.

Figure 5 is an enlarged view of the skid 73 as viewed from the left side in the direction of travel, and is a cross-sectional view of the fulcrum tube 71 and the support shaft 72. The skid 73 is also shown in a state in which it has been moved upward. As shown in Figure 5, a regulating pin 74 is provided on the lower end side of the fulcrum tube 71 in a direction intersecting the axial direction of the fulcrum tube 71. Both ends of the regulating pin 74 are fitted with retainers to prevent it from coming off the fulcrum tube 71, and the position is fixed so that it does not come off the fulcrum tube 71. In this embodiment, the regulating pin 74 is made up of the shaft portion of a bolt, and the retainer 741 is made up of the head of the bolt and a nut. Of course, the shape of the regulating pin 74 is not limited to the one illustrated.

A restriction hole 75 is provided at the bottom of the support shaft 72 inserted into the fulcrum tube 71. The restriction hole 75 is configured with a diameter larger than the outer diameter of the restriction pin 74, and the restriction pin 74 is provided so as to be located on the inner diameter side of this restriction hole 75. The vertical movement of the support shaft 72 is restricted by the restriction pin 74 located on the inner diameter side of the restriction hole 75. In detail, when the support shaft 72 moves upward, the restriction pin 74 comes into contact with the inner lower part of the restriction hole 75, and the support shaft 72 is restricted so that it cannot move upward any further. Conversely, when the support shaft 72 moves downward, the restriction pin 74 comes into contact with the inner upper part of the restriction hole 75, and the support shaft 72 is restricted so that it cannot move downward. In other words, the support shaft 72 can move up and down within the range in which the restriction pin 74 can move within the restriction hole 75.

When the lower part of the restriction hole 75 comes into contact with the restriction pin 74, even if the skid 73 is pushed upward by the work surface, the upward movement is restricted by the restriction hole 75. Therefore, the relative height of the skid 73 and the working part 51 changes only within the range between the restriction pin 74 and the restriction hole 75, so that the height of the cutting blade 511 of the working part 51 above the ground can be secured, and damage to the cutting blade 511 due to contact with the ground can be prevented. Although the restriction hole 75 in the embodiment is shown as a round hole, there is no limitation on the shape, and it may be an elongated hole or other shapes.

As shown in FIG. 6, a skid biasing body 76 that biases the skid 73 downward is provided on the upper part of the support shaft 72. In this embodiment, a compression spring is used as the skid biasing body 76. The skid biasing body 76 is located between the inside of the upper end side of the fulcrum tube 71 and the step portion 721 on the upper part of the support shaft, and biases the support shaft 72 downward. Therefore, the force that moves the support shaft 72 upward exceeds the biasing force of the skid biasing body 76, and the skid 73 moves upward relative to the fulcrum tube 71.

The skid 73 fixed to the lower part of the support shaft 72 is located below the working arm 50 and is a long sled-shaped member having a curved portion 731 that contacts the ground, which is the working surface. The skid 73 is installed so that its longitudinal direction always faces the direction of travel. The curved portion 731 of the skid 73 contacts the working surface and glides on the working surface, preventing the cutting blade 511 of the working part 51 from getting too close to the working surface.

The curved portion 731 is set to be larger than the radius of rotation of the cutting blade 511. In this embodiment, the radius of curvature of the curved portion 731 is 350 mm, and the radius of rotation of the cutting blade 511 is 260 mm. In other words, by setting the dimensional relationship such that the radius of curvature of the curved portion 731 is 1.35 times larger than the radius of rotation of the cutting blade 511, the skid 73 is prevented from getting stuck in small depressions that exist on the work surface. Since the skid 73 does not move up and down sensitively to small depressions, the working part 51 also does not move up and down sensitively on the work surface. In other words, the cutting blade 511 is prevented from coming into contact with small depressions, etc., and damage to the working part 51 is prevented.

The curved portion 731 slides while in contact with the work surface, and moves up and down relative to the fulcrum tube 71 within the range in which the regulating pin 74 can move through the regulating hole 75 in response to the unevenness of the work surface. When the skid 73 separates from the work surface, the skid biasing body 76 causes the skid 73 to descend until the curved portion 731 touches the ground, or until the regulating pin 74 is regulated by the regulating hole 75.

The skid 73 is located at the front end of the grass cutting device 1, so it can reach the unevenness before the working part 51, which works as it moves forward, reaches the unevenness. This prevents the working part 51 moving forward from suddenly coming into contact with the unevenness and being damaged. In other words, it is possible to catch the unevenness of the ground before the working part 51. In addition, since the curved radius of the curved part 731 is set to be larger than the turning radius of the cutting blade 511, it does not react sensitively to small unevenness and can prevent the lower part of the working part 51 from coming into contact with the working surface. Because the curved radius of the curved part 731 is large, the working part 51 does not get stuck in a depression smaller than the turning radius of the cutting blade 511, so grass cutting work can be continued stably.

As shown in FIG. 6, an operating piece 78 is fixed to the upper part of the support shaft 72. FIG. 6 is an enlarged view of the periphery of the operating piece 78, and a partial cross-section of the fulcrum tube 71. The right side of the figure is the front in the direction of travel. The operating piece 78 is in a raised state together with the support shaft 72, and a switch 79 provided on the operating piece 78 is in a state of abutting against the lower surface of the second frame 30. The operating piece 78 is a plate-like member that is bent downward from the upper part of the support shaft 72 and hangs down, and moves up and down together with the support shaft 72. The lower end of the operating piece 78 is bent downward of the second frame 30, which is a frame, and toward the rear side of the fulcrum tube 71 in the direction of travel to position an attachment part 781 for attaching the switch 79. The switch 79 attached to the attachment part 70 moves up and down in accordance with the up and down movement of the support shaft 72 and the operating piece 78.

The switch 79 is located below the second frame 30 and behind the fulcrum tube 71 in the direction of travel. By arranging the switch 79 below the second frame 30, the switch 79 is protected by the second frame 30 in situations where an obstacle is located above the second frame 30. Also, by arranging the switch 79 behind the fulcrum tube 71, the switch 79 is protected by the fulcrum tube 71 even if an obstacle moves relatively from the front of the fulcrum tube 71. In other words, the switch 79 is arranged in a position that is in the shadow of an obstacle that exists on the front and upper sides of the frame 2, so that damage during work can be prevented. Furthermore, a cover can be provided to cover the upper part of the operating piece 78 and the upper part of the support shaft 72. This cover protects the operating piece 78 and the upper part of the support shaft 72, and further prevents the operation of the switch 79 from being hindered by an obstacle.

The switch 79 is connected to a control unit 8 that is installed separately from the grass cutting device 1. Although not shown in the embodiment, it is arranged around the boom device A. When the switch 79, which moves up and down, reaches near the top dead center, it comes into contact with the underside of the second frame 30 and emits a detection signal. In other words, it emits a detection signal that detects that the skid 73 has moved upward. On the other hand, when the switch 79 moves downward from near the top dead center, the switch 79 moves in a direction away from the underside of the second frame 30. Then, it emits a signal that indicates that the switch 79 has left the underside of the second frame 30. In other words, it emits a detection signal that detects that the skid 73 has moved downward.

The control unit 8 can detect the operation status of the switch 79 by receiving a signal from the switch 79. In other words, the control unit 8 is configured to be able to distinguish, by the switch 79, whether the skid 73 is moving upward or downward. In the embodiment, a limit switch, which is a mechanical switch, is used as the switch 79, but the form of the switch 79 is not limited to this. For example, the switch 79 may be an optical or sonic switch. In addition, the switch 79 may be a displacement sensor that detects the amount of displacement or change due to the up and down movement of the skid 73 or the support shaft 72.

As shown in FIG. 9, the control unit 8 is connected to a switch 79 and a directional control valve H. The directional control valve H shown in FIG. 8 sends fluid pressure generated by a hydraulic pump P to a cylinder J provided in the boom device A in response to a command from the control unit 8, thereby operating the boom device A. The operation of the boom device A allows the grass cutting device 1 to move up and down. In this embodiment, multiple directional control valves H are provided, such as directional control valves H1, H2, H3, and H4, and multiple cylinders J are provided, such as cylinders 1J, J2, J3, and J4. The control unit 8 operates at least one directional control valve H to extend or retract at least one cylinder J and operate the boom device A.

The control unit 8 receives a detection signal from the switch 79 and issues an operation command to the directional control valve H based on this detection signal, thereby operating the directional control valve H and switching the direction of the fluid pressure output. The cylinder J that receives the fluid pressure expands and contracts, thereby operating the boom device A, and as a result, the grass cutting device 1 can move up and down.

Using Figure 10, we will explain the operation control of the grass cutting device 1 by the switch 79 and the control unit 8.

First, when control is started, in step S1, the control unit 8 determines whether the skid 73 is raised. That is, it determines whether the switch 79 is raised relative to the fulcrum tube 71 and in contact with the second frame 30. If the control unit 8 determines that the switch 79 is not raised relative to the fulcrum tube 71 and is not in contact with the second frame 30, that is, if it determines that the skid 73 is not raised, the control unit 8 repeats the determination in step 1 again.

When the switch 79 rises relative to the fulcrum tube 71 and comes into contact with the second frame 30, the switch 79 issues a detection signal to the control unit 8, which is a signal that detects the rise. Upon receiving this detection signal, the control unit 8 determines that the switch 79 has come into contact with the second frame 30. In other words, the control unit 8 can determine that the skid 73 has risen. If it is determined that the skid 73 has risen, the process proceeds to the next step S2.

In step S2, the control unit 8 operates the directional control valve H to extend and retract the cylinder of the boom device, thereby raising the boom device. As a result, the grass cutting device 1 connected to the boom device 2 by the attachment unit 10 also rises.

Next, in step S3, it is determined again whether the skid 73 is rising relative to the fulcrum tube 71. If the switch 79 rises relative to the fulcrum tube 71 and remains in contact with the second frame 30, the switch 79 continues to issue a detection signal to the control unit 8, which is a signal that detects the rise. The control unit 8, which has received the rise detection signal, repeats the determination in step 3 again. If the switch 79 falls relative to the fulcrum tube 71 and separates from the second frame 30, the switch 79 issues a detection signal to the control unit 8, which is a signal that detects the descent. The control unit 8, which has received the descent detection signal, performs the operation of the next step 4.

In step 4, the control unit 8 operates the directional control valve H to stop the extension and retraction of the cylinder of the boom device, thereby stopping the lifting of the boom device. In other words, the lifting of the grass cutting device 1 stops. The process returns to step 1 again, and the above series of control steps are repeated.

By detecting the vertical movement of the skid 73 relative to the fulcrum tube 71, the control unit 8 can detect the undulations of the work surface on which the grass cutting device 1 advances before the working unit 51 reaches it. When the control unit 8 detects that the skid 73 moves upward, that is, that there are protruding parts such as undulations or obstacles on the work surface, it can operate the boom device A to raise the working unit 51. When the skid 73 moves downward, that is, that there are no protruding parts such as depressions or obstacles on the work surface, it stops the boom device A and maintains the vertical position of the working unit 51. In other words, even if there is no protruding part on the work surface at the skid 73, the working unit 51 maintains its current vertical position, so that even if there is another obstacle hidden in the grass, there is no risk of the working unit 51 accidentally damaging the obstacle. In addition, the working unit 51 will not be damaged by the obstacle. When lowering the working unit 51, the operator operates the directional control valve H to extend and retract the cylinder J to operate the boom device A, thereby lowering the working unit 51. In other words, the worker can lower the working part after confirming that there are no obstacles, so that the obstacles and the working part 51 can damage each other.

The curved portion 731 of the skid 73 prevents the skid 73 from getting caught in small uneven surfaces. Since there is no excessive up and down movement, the boom device A does not operate excessively due to frequent detection signals from the switch 79.

The boom device in the embodiment has multiple booms or arms, but as long as it is possible to move the grass cutting device 1 up and down, it is sufficient for the boom device A to have one or more booms or arms that can move up and down or rotate.

The skid 73 moves vertically via the support shaft 72, so the amount of unevenness on the work surface can be directly reflected in the skid 73, and the support shaft 72 can be moved up and down. As a result, the switch 79 can be operated at an appropriate frequency depending on the height of the ground surface, and the boom device A does not operate excessively. In addition, the skid biasing body 76 arranged on the support shaft 72 constantly biases the skid 73 downward, preventing the skid 73 from remaining in an upward position when there is no foreign object on the underside of the skid, and eliminating factors that impede the detection operation of the switch 79.

The present invention has been described by the above embodiments and examples, but the descriptions and drawings that form part of this disclosure should not be understood as limiting the present invention. Modifications of the embodiments, examples, and operating techniques based on this disclosure are possible within the scope described in the claims.

REFERENCE SIGNS LIST 1 Grass cutting device 2 Frame 31 Fulcrum shaft 50 Working arm 51 Working section 511 Cutting blade 512 Motor 513 Cover member 58 Working section skid 581 Inclined section 582 Ground contact section 582s Ground contact point 59 Bowl-shaped ground contact body 71 Fulcrum tube 72 Support shaft 73 Skid 731 Curved section 76 Skid biasing body 78 Operation piece 79 Switch A Boom device S Passing space

Claims (6)

A boom device having at least one boom, the boom being arranged to be vertically rotatable;
a frame provided at a tip portion of the boom device and extending forward from the tip portion of the boom device in a traveling direction;
a working arm having one end supported so as to be rotatable in a substantially horizontal direction by a fulcrum shaft provided in the vicinity of a fulcrum cylinder provided on the frame, and having a working section on the other end capable of performing ground work;
a skid having a support shaft provided coaxially with the fulcrum tube, capable of moving vertically relative to the fulcrum tube by the support shaft, and provided at a lower end of the support shaft and capable of contacting a work surface;
a switch that can be operated via the support shaft that moves up and down in accordance with the up and down movement of the skid;
a control unit that rotates the boom upward when the switch detects an upward movement of the skid and releases the boom rotation when the switch detects a downward movement of the skid;
A grass cutting device comprising: The switch has an operation piece connected to an upper end of the support shaft, capable of moving up and down in synchronization with the up and down movement of the support shaft, and capable of operating the switch;
The grass cutting device according to claim 1, further comprising: The switch is located near the fulcrum tube and behind the fulcrum tube in the traveling direction.
3. The grass cutting device according to claim 1 or 2. The switch is located below the upper end of the support shaft and below the frame.
4. The grass cutting device according to claim 1, wherein the grass cutting device is a brush cutter. The skid has a curved portion having a front end portion curved upward in an arc shape,
The radius of the curved portion is greater than the rotation radius of the cutting blade of the working unit.
5. A grass cutting device according to claim 1, wherein the grass cutting device is a brush cutter. The support shaft includes a biasing body that constantly biases the skid downward;
The grass cutting device according to any one of claims 1 to 5, further comprising:

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