Grass cutting equipment

Abstract

To provide a grass mower capable of following a ground surface while securing a reaping height of a reaping blade which a turnable work part has.SOLUTION: A grass mower includes: a frame extending forward in a traveling direction; a work arm having one end side supported turnably in an almost horizontal direction by a turning fulcrum part disposed in the front part of the frame; a work part capable of ground work and having a rotary reaping blade at the other end side of the work arm; and a plurality of skids positioned at a lateral part along the rotation direction of the reaping blade and having grounding parts capable of grounding. The grounding part of at least one skid of the plurality of skids faces a traveling direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a grass cutting device mounted on a traveling body such as a tractor. In particular, the present invention relates to a grass cutting device capable of following the undulations of the ground and performing work.

Background Art

[0002] When performing grass cutting work using a grass cutting device, it is a known technique to maintain the height position of the cutting blade from the cutting surface using a grounding member such as a sled or skid. Also, it is a known technique for the working part to turn backward or turn left and right in the lateral direction with respect to the traveling direction and perform a retreating operation due to the load on the rear side received during traveling or contact with an obstacle or the like. These known techniques are disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the grass cutting main body, which is the working part described in Patent Document 1, rotates by a support rod due to the load received during traveling, or when it laterally moves to the side of the traveling direction of the working part by a boom, the camber plate that protrudes forward in the traveling direction from the rotary cutting blade pushes down the grass that is the object to be cut. In such a case, the cutting blade may not be able to cut the grass that is the object to be cut, and thus uncut grass may occur.

[0005] Therefore, the present invention has been made by focusing on the above problems, and an object of the present invention is to provide a grass cutting device that can follow the ground while ensuring the cutting height of the cutting blade of a working part having a rotatable working part.

Means for Solving the Problems

[0006] One aspect of the present invention for achieving the above object is a lawn mowing device including a frame extending forward in the traveling direction, a working arm having one end rotatably supported in a substantially horizontal direction at a pivot portion provided at the front portion of the frame, a working portion having a rotating cutting blade capable of performing ground work at the other end of the working arm, and a plurality of skids located on a side portion along the rotation direction of the cutting blade and having a grounding portion capable of grounding. The gist is that, among the plurality of skids, the grounding portion of at least one skid faces the traveling direction.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a lawn mowing device that can follow the ground while ensuring the cutting height of the cutting blade of the rotatable working portion.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0009] With reference to the drawings, an embodiment of the present invention will be described. In the description, the left side shown in FIG. 1 is the right side with respect to the traveling direction, the right side is the left side with respect to the traveling direction, the left side shown in FIG. 2 is the front side with respect to the traveling direction, and the right side is the rear side with respect to the traveling direction. The left side shown in FIGS. 3 to 5 will be described as the front side with respect to the traveling direction, and the right side shown in FIG. 6 will be described as the front side with respect to the traveling direction. Also, in the description, the upward direction refers to the direction away from the ground side which is the working surface, and the downward direction refers to the direction approaching the ground side. In the description of the drawings, the same or similar parts may be denoted by 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 relationships with the dimensions of each part may be different from the actual ones. Further, various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims described in the claims.

[0010] As shown in FIG. 7, the mowing device 1 is attached to a traveling machine body T composed of a tractor or the like by a boom device A which is a mounting frame composed of a single or a plurality of booms. FIG. 7 shows an example in which the mowing device 1 is attached to a boom device A which is telescopic or bendable by a cylinder or the like composed of a plurality of boom devices A attached to the rear of the traveling machine body T. By vertically swinging the boom of the illustrated boom device A about a pivot axis, the mowing device 1 can be moved in the vertical direction with respect to the traveling machine body T.

[0011] The mowing device 1 shown in FIGS. 1 to 4 is attached to the boom device A by the attachment part 10. A frame 2 extending forward in the traveling direction is attached to the attachment part 10. The mowing device 1 includes a working arm 50 that is located below the frame 2, is horizontally rotatable, and has a working part 51 attached to the tip of the rotating radial direction. The working part 51 includes a plurality of horizontally rotating cutting blades 511, and performs a mowing operation by rotationally driving the cutting blades 511. Since the working part 51 is horizontally rotatable by the working arm 50, obstacles moving relative from the front side can be passed while performing a turning operation. Since the working part 51 is arranged to protrude from the attachment part 10 by the frame 2, the work can be performed even in a place where there is an obstacle covering the upper part of the working part 51. Below the front end of the frame 2, a skid 73 that contacts the ground, which is the working surface, is provided, and the working part 51 can be maintained at a constant height. Further, the front of the working part 51 and the skid 73 are arranged to further improve the height maintenance of the working part 51.

[0012] The attachment part 10 can be integrally fixed to the boom device A by fitting it to the tip of the boom device A, and the fixation to the boom device A can be released by releasing this fixation. That is, the mowing device 1 is detachable from the boom device A. In the embodiment, the boom device A is fixed to the upper part of the attachment part 10, but there is no limitation on the fixing position. Further, a rolling fulcrum part A1, which is a shaft facing the traveling direction, is provided at the tip of the boom device A, and the mowing device 1 can be turned left and right.

[0013] One end on the left side in the traveling direction of the attachment part 10 fixes the rear end of the frame 2. The frame 2 in the embodiment is composed of a first frame 20 that is long in the front direction and a second frame 30 that is connected to the front end of the first frame 20 by a bending shaft 40 and is horizontally rotatable with respect to the first frame 20. The first frame 20 is a long member and is arranged so that the long direction 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 in this holder part 22. The rear end of the second frame 30 is connected to the bending shaft 40 so as to be horizontally rotatable.

[0014] The second frame 30 is a long member and is arranged so that its long direction protrudes forward. In the embodiment, the second frame 30 in plan view is arranged with its long direction inclined with respect to the first frame 20. By providing the second frame 30 so as to be rotatable about the bending axis 40 as a fulcrum, when a load is applied to the second frame 30 due to a collision with an obstacle or the like on the rear side in the traveling direction, the second frame 30 rotates to the rear side, and damage to the frame 2 can be prevented. In the embodiment, the frame 2 is provided with the first frame 20 and the second frame 30 so as to be bendable, but they may be integrally provided so as not to be bendable.

[0015] A 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 a fulcrum cylinder 71 which protrudes downward from the front end of the second frame 30. The fulcrum cylinder 71 is a member for supporting a support shaft 72 of the skid 73. The fulcrum cylinder 71, the skid 73, and the support shaft 72 will be described later.

[0016] The fulcrum shaft 31 is a shaft in the vertical direction and is provided below the front end side of the frame 2. In the case of the embodiment, it is arranged behind the middle of the fulcrum cylinder 71 which hangs downward from the front end of the frame 2. One end side of the working arm 50 is attached to the fulcrum shaft 31. The working arm 50 is rotatable horizontally about the fulcrum shaft 31.

[0017] A working part 51 is provided on the other end side which is the side away from the axis of the fulcrum shaft 31 of the working arm 50 in the radial direction. The working part 51 is a working part capable of performing an operation of mowing grass growing on the ground. The working part 51 includes a mowing blade 511, a motor 512, and a cover member 513. A motor 512 is provided on the other end side of the working arm 50, and the mowing blade 511 arranged below this is rotationally driven. A plurality of mowing blades 511 are provided, and they are rotatable horizontally about the motor 512 as an axis and rotate receiving the rotational power of the motor 511. The grass existing on the working surface can be mowed by the rotating mowing blades 511.

[0018] The working arm 50 is provided with a cover member 513. The cover member 513 is a member imitating a drop shape in plan view, and the drop-shaped protrusion is arranged facing the fulcrum shaft 31 side. The cover member 513 is located above the cutting blade 511 and prevents the upward scattering of objects such as cut grass scattered by the cutting blade 511. In the case of the embodiment, in plan view, the other end of the working arm 50 is positioned behind the fulcrum shaft 31, and the motor 512 serving as the rotation drive shaft of the cutting blade 511 is positioned on the side of the frame 2.

[0019] By horizontally swinging around the fulcrum shaft 31, the working arm 50 can be positioned in the first working area B on the left side of the traveling direction and the second working area C on the right side of the traveling direction, which are divided by the longitudinal direction passing through the fulcrum shaft 31 with respect to the working part 51 shown in FIG. 3. The working part 51 shown by the solid line in FIG. 3 indicates the state of being located in the first working area B, and the working part 51 shown by the two-dot chain line indicates the state of being located in the second working area. The grass cutting operation is performed by the working part 51 located in each area.

[0020] A switching piece 55 is provided on the fulcrum shaft 31 separately from the working arm 50 and capable of swinging coaxially around the working arm 50. The switching piece 55 is provided separately from the working arm 50 and swings 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 case of the embodiment, the long hole 551 is provided on the first working area B side which is the one end side. A swing restricting body 52 is passed through the long hole 551. Since the center of the arc of the arc-shaped long hole 551 is provided coaxially with the fulcrum shaft 31, the switching piece 55 can swing freely within the long hole 551.

[0021] The swing restricting body 52 is a rod-shaped member long in the vertical direction, is arranged near the fulcrum shaft 31 and penetrates through the long hole 551. Further, by contacting the working frame 51, the swing restricting body 52 restricts the swing angle of the working frame 51 toward the forward direction side in each of the first working area B and the second working area C.

[0022] A rod-shaped guide rod 57 is rotatably arranged at the other end of the switching piece 55. The guide rod 57 is arranged so as to span a guide rod fulcrum portion 571 provided at the other end of the switching piece 55 and a guide rod holding portion 572 provided at the other end side of the working arm 50. As shown in FIG. 3, when the working portion 51 is positioned in the first working area B, the guide rod fulcrum portion 571 is provided on the second working area C side. The guide rod holding portion 572 is located in the first working area B and holds the guide rod 57 slidable in the axial direction without inhibiting the turning operation of the working arm 50.

[0023] An urging body 56 for urging the working arm 50 to one side of either the first working area B or the second working area C is arranged on the outer periphery of the guide rod 57. In the case of the embodiment, the urging body 56 uses a compression spring. The guide rod 57 has a role of guiding so that the urging body 56 does not shift. An urging body regulating portion 573 is fixed to the guide rod fulcrum portion 571 side of the guide rod 57. The urging body 56 urges the working arm 50 by expanding and contracting between the urging body regulating portion 573 and the guide rod holding portion 572. By the urging body 56, the working portion 51 and the working arm 50 are urged forward in the advancing direction.

[0024] Here, the operation of the switching piece 55 will be described. By rotating the switching piece 55 around the fulcrum shaft 31, the urging direction of the urging body 56 is changed, and the working arm 50 is pushed to one side of 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 urging body 56 and turns until the working arm 50 contacts the turning restricting body 52, and the turning is restricted at the position where the working arm 50 contacts the turning restricting body 52.

[0025] FIG. 3 shows a state where the working arm 50 and the working unit 51 are located in the first working area B. The arc-shaped arrow shown in FIG. 3 indicates a first rotation direction D and a second turning direction E, which are the rotation directions around the fulcrum axis 31 of the working arm 50, the working unit 51, and the switching piece 55. When the working unit 51 is located in the first working area B, the guide rod fulcrum portion 571 of the switching piece 55, which is located behind the fulcrum axis 31 and on the second working area C side, is pushed by the biasing body 56 to turn the switching piece 55 in the second turning direction E, which is the left-turning direction in plan view. The turning of the switching piece 55 in the second turning direction E is performed until the turning regulator 52 contacts one end of the long hole 551, and after the contact, the turning of the switching piece 55 is restricted. The biasing body 56 continues to bias the switching piece 55, whose turning is restricted, in the second turning direction E, and by pushing the guide rod holding portion 572, turns the working arm 50 in the first turning direction D, which is the right-turning direction in plan view, until the working arm 50 contacts the turning regulator 52. That is, the working arm 50 and the working unit 51 are biased forward in the traveling direction in the first working area. In the first working area B, the position where the working arm 50 contacts the turning regulator 52 is called the return position in the first working area B.

[0026] In this way, the working part 51 located in the first working area B can be expanded away from the side of the frame 2 and positioned at the return position in the first working area B by being biased in the first turning direction D by the switching piece 55 and the biasing body 56. Further, when the working part 51 and the working arm 50 are pushed rearward by an external force, they turn and move in the second turning direction E according to the external force. At this time, the distance between the guide rod holding part 572 and the biasing body regulating part 573 is reduced, and the biasing body 56 is compressed. The compressed biasing body 56 is in a state where the repulsive force is increased. Since the guide rod fulcrum part 571 is on the second working area C side from the line segment connecting the fulcrum shaft 31 and the guide rod holding part 572, when the above external force is removed, the working arm 50 receiving the biasing force by the biasing body 56 returns to the return position in the first working area B. In this case, the external force in actual work refers to an obstacle higher than the working part such as a pillar, and when this obstacle collides with the working part, the working arm 50 and the working part 51 turn rearward within the first working area B. Then, when the external force is removed, the working arm 50 and the working part 51 return to the return position.

[0027] As shown by the two-dot chain line portion 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 in the second turning direction E. If the working arm 50 continues to rotate in the second turning direction E, eventually, the working arm 50 and the working unit 51 will be located on the second working area C side. If further rotation continues, the fulcrum shaft 31, the guide rod fulcrum portion 571, and the guide rod holding portion 572 will be arranged in a straight line in a plan view. Furthermore, if rotation continues, since the guide rod fulcrum portion 571 is located on the first working area B side of the virtual line segment connecting the fulcrum shaft 31 and the guide rod holding portion 572, the switching piece 55 rotates in the first turning direction D by the biasing body 56. The switching piece 55 rotates until the turning restricting body 52 contacts the other end of the long hole 551, and thereafter, the turning in the first turning direction D is restricted by the turning restricting body 52. Then, the working arm 50 and the working unit 51 are located in the second working area C and are biased forward in the traveling direction, which is the second turning direction E, by the biasing body 56. The biasing body 56 continues to bias the switching piece 55 with restricted turning in the first turning direction D and rotates the working arm 50 in the second turning direction E, which is the left rotation direction in a plan view, until the working arm 50 contacts the turning restricting body 52. This position is called the return position in the second working area C.

[0028] The working unit 51 located in the second working area C can be biased in the second turning direction E by the switching piece 55 and the biasing body 56, expanded so as to move away from the side of the frame 2, and positioned at the return position in the second working area C. Also, when the working unit 51 and the working arm 50 are pushed backward by an external force such as an obstacle, they rotate and move in the first turning direction D according to the external force, but when this external force is removed, they return to the return position in the second working area C. To move the working unit 51 located in the second working area C to the first working area B, since it is similar to the above-described procedure, this description is omitted.

[0029] By using the switching piece 55, one working part 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 as to face the return position corresponding to each deployment position.

[0030] On the radial side part of the rotating cutting blade 511, a working part skid 58 which is a skid is provided. The working part skid 58 is a rod-shaped skid member formed of a rod-shaped member, and a plurality of them are provided around the side of the cutting blade 511. In the case of the embodiment to be described, the working part skids 58 are provided at two places around the side of the cutting blade 511 symmetrically with respect to the longitudinal direction of the working arm 50. In the description, one working part skid 58 is referred to as the first working part skid 58a, and the other is referred to as the second working part skid 58b.

[0031] In plan view and bottom view, the working part skid 58 is provided so as to be curved along the circumferential direction of rotation of the cutting blade 511. Further, the working part skid 58 in side view is connected to the lower part of the cover member 513 and includes an inclined part 581 inclined rearward as it goes downward, a grounding part 582 extending horizontally from the lower end of the inclined part 581, and a rising part 583 rising from the rear end of the grounding part 582 and having its upper part connected to the lower part of the cover member 513. Although the illustrated working part skid 58 is formed of a rod-shaped member, it is not limited thereto, and it may be formed of a plate-shaped member or the like, and the installation locations may be two or more.

[0032] The first working part skid 58a which is one of the working part skids 58 in the first working area B will be described. In the first working area B, the first working part skid 58a is arranged at the position farthest from the advancing direction width direction with respect to the fulcrum shaft 31 as a reference. The inclined part 581a of the first working part skid 58a reaches the rear while curving along the rotation direction of the cutting blade 511 from the front side of the cutting blade 511 in plan view. The grounding part 582a of the first working part skid 58a following the inclined part 581a is long, and the long direction faces the advancing direction. A rising part 583a is arranged from the rear end of the grounding part 582a and is connected to the cover member 513.

[0033] The inclined portion 581a of the first working unit skid 58a guides the undulations of the ground, which is the working surface moving relatively from the front as the mowing operation advances, to the rear grounding portion 582a. During the guiding, due to the inclination of the inclined portion 581a, the mowing device 1 is gradually lifted with a rolling motion about the rolling fulcrum portion A1 at the tip of the boom device A. That is, the cutting blade 511 is also lifted along with the undulations of the ground. When the grounding portion 582a contacts the ground and then slides on the ground along the longitudinal direction, the relative height between the cutting blade 511 and the undulating ground can be maintained.

[0034] When the undulations of the ground reach the rising portion 583a, which is the rear end portion of the grounding portion 582a, since there is nothing to support the working unit 51, the working unit 51 descends again about the rolling fulcrum portion A1 along with the undulations of the ground. By configuring it in this way, it is possible to prevent the undulations of the ground from contacting the rotating cutting blade 511. The inclined portion 581a and the grounding portion 582a are arranged at the positions farthest from the rolling fulcrum portion A1 and the fulcrum shaft 31 in plan view. By guiding the undulations of the ground at the outermost edge of the working width of the cutting blade 511 with the first working unit skid 58a, it is possible to ensure the cutting height of the cutting blade 511 and protect the cutting blade 511 from contact with the ground. Further, by arranging the grounding portion 581a at the outermost edge of the working width, the grounding portion 582a can be separated from the rolling fulcrum portion A1, and the rolling operation of the working unit 51 can be performed more reliably. That is, the force required for the turning operation by the rolling fulcrum portion A1 is reduced and the turning is performed smoothly. And it is possible to prevent the inclined portion 581a and the grounding portion 582a from biting into the ground.

[0035] As described above, the working unit 51 may be moved up and down by bending a plurality of booms of the boom device without raising and lowering the rolling fulcrum portion A1.

[0036] The second working part skid 58b, which is the other working part skid 58 in the first working area B, will be described. The inclined part 581b of the second working part skid 58b is located on the side of the fulcrum axis 31 in the width direction of the traveling direction with respect to the inclined part 581a of the first working part skid 58a, and is located slightly rearward. The inclined part 581b with respect to the inclined part 581a does not prevent the rolling motion due to the undulation at the inclined part 581a and the grounding part 582a, which are the skids on one side, and does not get stuck in the ground.

[0037] The grounding part 582b following the inclined part 581b is located on the rear side of the cutting blade 511, and the longitudinal direction is arranged in a direction intersecting the traveling direction. That is, the longitudinal direction of the grounding part 582b of the second working part skid 58b is arranged in a direction intersecting the longitudinal direction of the grounding part 582a of the first working part skid 58a. Also, the grounding part 582b will be located at the rear end of the working part 51. By arranging it in this way, the undulation that relatively moves to the working part 51 from the front is received by the first working part skid 58a ahead of the second working part skid 58b. That is, the second working part skid 58b in the first working area B does not prevent the rolling motion of the working part 51.

[0038] The other second working part skid 58b in the first working area B has the longitudinal direction of the grounding part 582b arranged in a direction intersecting the traveling direction. That is, the longitudinal direction of the grounding part 582b is in a state substantially facing the turning direction around the fulcrum axis 31 of the working part 51. For this reason, the second working part skid 58b does not prevent the horizontal turning motion of the working part 51 due to the turning around the fulcrum axis 31 of the working arm 50.

[0039] The grass cutting device 1 is configured such that the working part 51 can be projected to either the left or right in the traveling direction with respect to the fulcrum shaft 31. That is, the working part 51 can be positioned in the second working area C for work. When the working part 51 is positioned in the second working area C, the second working part skid 58b is arranged at the position farthest from the rolling fulcrum part A1 and the fulcrum shaft 31 in plan view. Further, the first working part skid 58a, which is one of the working part skids 58 in the second working area C, positions the inclined part 581a on the side of the fulcrum shaft 31 in the width direction in the traveling direction with respect to the inclined part 581b of the second working part skid 58b, and is also positioned slightly rearward.

[0040] The actions and effects of the first working part skid 58a and the second working part skid 58b in the second working area C are opposite to the actions and effects of the first working part skid 58a and the second working part skid 58b in the first working area B. Since this explanation is similar to the above explanation, it is omitted.

[0041] When the working part 51 is positioned in the first working area B, the grounding part 582a of the first working part skid 58a faces the traveling direction. When the working part 51 is positioned in the second working area C, the grounding part 582b of the second working part skid 58b faces the traveling direction. That is, among the grounding parts 582 of the plurality of arranged working part skids 58, the longitudinal direction of at least one grounding part 582 faces the traveling direction when the working part 51 is positioned in either the first working area B or the second working area C. With such a configuration, the up-and-down movement due to the rolling operation of the working part 51 is smoothly performed to make a following operation with respect to the ground, and by horizontally turning around the fulcrum shaft 31 of the working part 51, an obstacle that relatively moves from the front of the grass cutting device 1 and collides with the working part 51 can be bypassed.

[0042] The illustrated working part skids 58 are shown arranged at two locations along the circumferential direction of rotation of the cutting blade 511, but may be arranged at three or more locations. In this case, it is only necessary that the longitudinal direction of the grounding part 582 of at least one working part skid 58 faces the traveling direction.

[0043] The portion 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 an object can pass. Since the passage space S does not block the path of an object such as mowed grass scattered laterally from the cutting blade 511, no object accumulates between the working part skid 58 and the cutting blade 511. That is, since the cutting blade 511 can operate without contact with foreign objects, it can cut grass, which is the object to be cut moving relatively from the front in the traveling direction, without applying a load to the cutting blade 511 and the motor 512 that rotationally drives it.

[0044] A bowl-shaped grounding body 59 is provided at the lower part of the working part 51. The bowl-shaped grounding body 59 is provided coaxially with the rotation axis of the cutting blade 511. Since the bowl-shaped grounding body 59 is rotatably attached independently of the rotation of the cutting blade, even when this bowl-shaped grounding body contacts the ground, it can maintain a stationary state and prevent the cutting blade from contacting due to the undulation of the ground.

[0045] The grounding point s1 at the lowermost end of the bowl-shaped grounding body is positioned above the grounding point 582s at the lower part of the grounding portion 582 of the working part skid 58. In the lower part of the working part 51, the portion that can contact the ground has a two-stage structure of the working part skid 58 and the bowl-shaped grounding body 59.

[0046] By guiding most of the large undulations with the working part skid 58, the working part 51 is moved up and down. At the same time, the bowl-shaped grounding body 59 catches the undulations of the ground that the working part skid 58 cannot fully guide, thereby moving the working part 51 up and down. When there are undulations on the ground approaching below the cutting blade 511 as it travels, the contact between the bowl-shaped grounding body 59 and the undulations of the ground pushes up the grass cutting device 1 via the working part 51. Then, the grass cutting device 1 moves up and down at the rolling fulcrum portion A1 near the attachment portion 10 and the boom device A.

[0047] A vertically long support shaft 72 that supports a skid 73 is coaxially inserted into a fulcrum cylinder 71 disposed downward from the front end of a frame 2. The support shaft 72 is provided so as to be vertically movable with respect to the fulcrum cylinder 71. Further, the skid 73 is fixed to the lower portion of the support shaft 72. That is, the skid 73 is provided so as to be vertically movable.

[0048] FIG. 5 is an enlarged view of the skid 73 as viewed from the left side in the traveling direction, and is a cross-sectional view of the fulcrum cylinder 71 and the support shaft 72. Further, the skid 73 is shown in a state of being moved upward. As shown in FIG. 5, a regulating pin 74 is provided on the lower end side of the fulcrum cylinder 71 in a direction intersecting the axial direction of the fulcrum cylinder 71. Both ends of the regulating pin 74 are provided with retaining means so that the position is fixed so as not to come out of the fulcrum cylinder 71. In the embodiment, the regulating pin 74 is constituted by the shaft portion of a bolt, and the retaining means 741 is constituted by the head of the bolt and a nut. Of course, the form of the regulating pin 74 is not limited to the exemplified one.

[0049] A regulating hole 75 is provided in the lower portion of the support shaft 72 inserted into the fulcrum cylinder 71. The regulating hole 75 is formed with a diameter larger than the outer diameter of the regulating pin 74, and the regulating pin 74 is provided so as to be positioned on the inner diameter side of the regulating hole 75. The vertical movement of the support shaft 72 is regulated by the regulating pin 74 positioned on the inner diameter side of the regulating hole 75. Specifically, when the support shaft 72 moves upward, the regulating pin 74 contacts the inner lower portion of the regulating hole 75, and the support shaft 72 is regulated so that it cannot move upward any further. Conversely, when the support shaft 72 moves downward, the regulating pin 74 contacts the inner upper portion of the regulating hole 75, and the support shaft 72 is regulated so that it cannot move downward. That is, the support shaft 72 can move vertically within the range in which the regulating pin 74 can move within the regulating hole 75.

[0050] When the lower part of the regulating hole 75 comes into contact with the regulating pin 74, even if the skid 73 is further pushed upward by the working surface, the upward movement is restricted by the regulating hole 75. Therefore, the relative height between the skid 73 and the working part 51 varies only within the range between the regulating pin 74 and the regulating hole 75, so that the ground clearance of the cutting blade 511 of the working part 51 can be ensured, and damage to the cutting blade 511 due to contact with the ground can be prevented. Although the regulating hole 75 in the embodiment is shown as a round hole, the shape is not limited, and it may be a long hole or other shapes.

[0051] As shown in FIG. 6, a skid biasing body 76 for biasing the skid 73 downward is provided on the upper part of the support shaft 72. The skid biasing body 76 in the embodiment uses a compression spring. The skid biasing body 76 is located between the inner part of the upper end side of the fulcrum cylinder 71 and the step portion 721 of the upper part of the support shaft, and biases the support shaft 72 downward. Therefore, when the force for the support shaft 72 to move upward exceeds the biasing force of the skid biasing body 76, the skid 73 moves upward with respect to the fulcrum cylinder 71.

[0052] 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 as the working surface. The skid 73 is provided such that its longitudinal direction always faces the traveling direction. When the curved portion 731 of the skid 73 contacts the working surface and slides on the working surface, the cutting blade 511 of the working part 51 is prevented from approaching the working surface too closely.

[0053] The curved portion 731 is provided to be larger than the rotation radius of the cutting blade 511. In the embodiment, the curvature radius of the curved portion 731 is 350 mm, and the rotation radius of the cutting blade 511 is provided at 260 mm. That is, by setting the dimensional relationship such that the curvature radius of the curved portion 731 is 1.35 times larger than the rotation radius of the cutting blade 511, the skid 73 is prevented from fitting into small depressions on the working surface. Since the skid 73 does not move up and down sensitively in small depressions, the working part 51 also does not move up and down sensitively on the working surface. That is, contact of the cutting blade 511 due to small depressions or the like is prevented, and damage to the working part 51 is prevented.

[0054] The bending part 731 slides while contacting the working surface, and moves up and down within the range where the regulating pin 74 can move in the regulating hole 75 with respect to the fulcrum cylinder 71 according to the undulations of the working surface. When the skid 73 separates from the working surface, the skid 73 descends by the skid biasing body 76 until the bending part 731 touches the ground, or until the regulating pin 74 is regulated by the regulating hole 75.

[0055] Since the skid 73 is located on the front end side of the lawn mowing device 1, the skid 73 can reach the undulations such as bumps and hollows of the working surface in advance before the working part 51 that works during forward movement reaches them. For this reason, the working part 51 moving forward does not suddenly contact the undulations and get damaged. That is, it becomes possible to catch the undulations of the ground before the working part 51. Also, since the bending radius of the bending part 731 is set larger than the rotation radius of the cutting blade 511, it does not react sensitively to small undulations and can prevent contact with the working surface below the working part 51. Since the bending radius of the bending part 731 is large, the working part 51 does not fit into a depression smaller than the rotation radius of the cutting blade 511, so the lawn mowing operation can be continued stably.

[0056] As shown in FIG. 6, an operation piece 78 is fixed to the upper part of the support shaft 72. FIG. 6 is an enlarged view around the operation piece 78 and shows a partial cross-section of the fulcrum cylinder 71. The right side shown in the figure is the front in the traveling direction. Also, the operation piece 78 is in a state of rising together with the support shaft 72, and the switch 79 provided on the operation piece 78 is in a state of abutting against the lower surface of the second frame 30. The operation 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. An attachment part 781 for attaching the switch 79 is positioned by bending the lower end part of the operation piece 78 below the second frame 30 which is a frame and on the rear side in the traveling direction of the fulcrum cylinder 71. The switch 79 attached to the attachment part 70 moves up and down as the support shaft 72 and the operation piece 78 move up and down.

[0057] The switch 79 is located below the second frame 30 and on the rear side in the advancing direction of the fulcrum cylinder 71. By arranging the switch 79 below the second frame 30, in a scenario where an obstacle or the like is located above the second frame 30, the switch 79 is protected by the second frame 30. Also, by arranging the switch 79 behind the fulcrum cylinder 71, even if there is an obstacle or the like that relatively moves from the front of the fulcrum cylinder 71, the switch 79 is protected by the fulcrum cylinder 71. That is, the switch 79 is arranged at a position that is in the shadow of the obstacles existing on the front side and the upper side of the frame 2, so that damage during operation 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. By this cover, the upper parts of the operating piece 78 and the support shaft 72 are protected, and it is possible to further prevent the operation of the switch 79 from being inhibited by an obstacle or the like.

[0058] The switch 79 is connected to a control unit 8 installed separately from the mowing device 1. Although not shown in the embodiment, it is arranged around the boom device A. When the switch 79 that moves up and down reaches near the top dead center, a detection signal can be emitted by contacting the lower surface of the second frame 30. That is, a detection signal is emitted to detect 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 lower surface of the second frame 30. Then, a signal is emitted to notify that the switch 79 has left the lower surface of the second frame 30. That is, a detection signal is emitted to detect that the skid 73 has moved downward.

[0059] By receiving the signal of switch 79, the control unit 8 can detect the operation status of switch 79. That is, the control unit 8 is provided so as to be able to identify whether the skid 73 is in an upward moving state or an upward moving state by the switch 79. The switch 79 in the embodiment uses a limit switch which is a mechanical switch, but the form of the switch 79 is not limited to this. For example, the switch 79 may be optical, sonic, etc. Further, the switch 79 only needs to be able to detect the displacement amount or change amount due to the vertical movement of the skid 73 or the support shaft 72, and it may also be a displacement sensor for detecting this.

[0060] As shown in FIG. 9, the control unit 8 is connected to the switch 79 and the direction control valve H. The direction control valve H shown in FIG. 8 sends the fluid pressure generated by the hydraulic pump P to the cylinder J provided in the boom device A according to the command of the control unit 8 to operate the boom device A. By the operation of the boom device A, the mowing device 1 can move in the vertical direction. In the embodiment, a plurality of direction control valves H such as direction control valves H1, H2, H3, and H4 are provided, and a plurality of cylinders J such as cylinders 1J, J2, J3, and J4 are provided. The control unit 8 operates at least one direction control valve H to expand and contract at least one cylinder J and operate the boom device A.

[0061] The control unit 8 receives the detection signal from the switch 79, and issues an operation instruction to the direction control valve H based on this detection signal to operate the direction control valve H and switch the fluid pressure transmission direction. The cylinder J that receives the fluid pressure expands and contracts to operate the boom device A, and as a result, the mowing device 1 can move in the vertical direction.

[0062] The operation control of the mowing device 1 by the switch 79 and the control unit 8 will be described with reference to FIG. 10.

[0063] First, when the control starts, in step S1, the control unit 8 determines whether the skid 73 is rising. That is, it determines whether the switch 79 has risen with respect to the fulcrum cylinder 71 and is in contact with the second frame 30. When the control unit 8 determines that the switch 79 has not risen with respect to the fulcrum cylinder 71 and is not in contact with the second frame 30, that is, when it determines that the skid 73 is not rising, the control unit 8 repeats the determination in step 1 again.

[0064] When the switch 79 rises with respect to the fulcrum cylinder 71 and comes into contact with the second frame 30, the switch 79 issues a detection signal, which is a signal indicating that it has detected the rise, to the control unit 8. By receiving this detection signal, the control unit 8 determines that it has come into contact with the second frame 30. That is, the control unit 8 can determine that the skid 73 has risen. When it is determined that the skid 73 has risen, the process proceeds to the next step S2.

[0065] In step S2, the control unit 8 operates the direction control valve H to expand and contract the cylinder provided in the boom device, thereby raising the boom device. Accordingly, the mowing device 1, which is two - connected to the boom device by the attachment part 10, also rises.

[0066] Next, in step S3, it is determined again whether the skid 73 is rising with respect to the fulcrum cylinder 71. When the switch 79 has risen with respect to the fulcrum cylinder 71 and remains in contact with the second frame 30, the switch 79 continues to issue a detection signal, which is a signal indicating that it has detected the rise, to the control unit 8. The control unit 8, which has received the detection signal indicating the rise, repeats the determination in step 3 again. When the switch 79 descends with respect to the fulcrum cylinder 71 and separates from the second frame 30, the switch 79 issues a detection signal, which is a signal indicating that it has detected the descent, to the control unit 8. The control unit 8, which has received the detection signal indicating the descent, performs the operation in the next step 4.

[0067] In step 4, the control unit 8 operates the direction control valve H to stop the expansion and contraction operation of the cylinder provided in the boom device, thereby stopping the rise of the boom device. That is, the rising operation of the mowing device 1 stops. Then, it returns to step 1 again and repeats the above - described series of control steps.

[0068] By detecting the vertical movement of the skid 73 with respect to the fulcrum cylinder 71, the control unit can detect the undulation of the working surface on which the mowing device 1 travels before the working unit 51 reaches it. When the skid 73 moves upward, that is, when it is detected that there are protrusions such as undulations or obstacles on the working surface, the control unit 8 can operate the boom device A to raise the working unit 51. When the skid 73 moves downward, that is, when it is detected that there are no depressions or protrusions such as obstacles on the working surface, the boom device A is stopped and the vertical position of the working unit 51 is maintained. That is, even when there is no protrusion on the working surface at the skid 73, the working unit 51 maintains its current vertical position, so that even if there are further obstacles hidden in the grass or the like, the working unit 51 will not accidentally damage the obstacles. Also, the working unit 51 will not be damaged by the obstacles. When lowering, the operator operates the direction control valve H to expand and contract the cylinder J to operate the boom device A, thereby lowering the working unit 51. That is, since the operator can lower the working unit after confirming that there are no obstacles, damage to each other between the obstacles and the working unit 51 can be avoided.

[0069] Due to the curved portion 731 of the skid 73, even if there are small uneven surfaces, the skid 73 will not fit into these uneven surfaces. Since it does not move up and down excessively, the detection signal by the switch 79 is not frequently transmitted, and the boom device A does not operate excessively.

[0070] The boom device in the embodiment has a plurality of booms or arms, but as long as the mowing device 1 can move up and down, the boom device A may have one or more booms or arms capable of vertical movement or swiveling movement.

[0071] Due to the support shaft 72, the skid 73 moves vertically, directly reflecting the unevenness of the working surface on the skid 73 and enabling the support shaft 72 to move up and down. As a result, the switch 79 can be set to an appropriate operation frequency with respect to the undulation height of the ground, and the boom device A does not operate excessively. Also, the skid biasing body 76 arranged on the support shaft 72 constantly biases the skid 73 downward, preventing the skid 73 from remaining in the upward movement when there is no foreign object on the lower surface of the skid, and eliminating the inhibiting factor for the detection operation by the switch 79.

[0072] Although the present invention has been described by the above embodiments and examples, the discussions and drawings forming a part of this disclosure should not be understood as limiting the present invention. Modifications of the embodiments, examples, and operation techniques based on this disclosure are possible within the scope described in the claims.

Explanation of Reference Numerals

[0073] 1 Lawn mowing device 2 Frame 31 Fulcrum shaft 50 Working arm 51 Working part 511 Mowing blade 512 Motor 513 Cover member 58 Working part skid 581 Inclined part 582 Ground contact part 582s Ground contact point 59 Bowl-shaped grounding body 71 Fulcrum cylinder 72 Support shaft 73 Skid 731 Curved part 76 Skid biasing body 78 Operating piece 79 Switch A Boom device S Passage space

Claims

1. A frame extended forward in the direction of travel, a working arm having one end supported on a pivot point provided at a front portion of the frame so as to be pivotable in a substantially horizontal direction; a working part having a rotating cutting blade capable of ground work, on the other end side of the working arm; a plurality of skids positioned on sides along a rotation direction of the blade and having long ground contact portions that can be grounded; The working arm is configured to rotate horizontally around the pivot point, so that the working unit can be positioned in a first working area on the left side of the traveling direction and a second working area on the right side of the traveling direction, the first working area being divided along a longitudinal direction passing through the pivot point, and the ground contact portion of at least one of the plurality of skids faces the traveling direction and is disposed at a position farthest from the pivot point. A grass cutting device characterized by the above.

2. The grounding portions of the plurality of skids are arranged in a direction intersecting each other.

2. The grass cutting device according to claim 1.

3. At least one of the plurality of skids is disposed on either the left or right side of the working unit in the traveling direction, and the other skids are disposed on the rear side of the working unit in the traveling direction.

3. The grass cutting device according to claim 1 or 2.

4. The ground contact portion facing the traveling direction is located at the outermost part of the working width in the traveling direction based on the pivot point portion.

4. A grass cutting device according to claim 1, wherein the grass cutting device is a brush cutter.

5. a passage space above the ground contact portion through which an object moving from the blade can pass; The grass cutting device according to any one of claims 1 to 4, further comprising:

6. A bowl-shaped ground contact body having a curved surface protruding downward is provided below the cutting blade, A ground contact point where the curved surface comes into contact with the ground is disposed at a position higher than a ground contact point where the ground contact portion comes into contact with the ground.

6. A grass cutting device according to claim 1, wherein the grass cutting device is a brush cutter.

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