Work vehicles

Abstract

To provide a work vehicle that can automatically adjust its tension when traversing uneven terrain such as steps. [Solution] A work vehicle comprising a vehicle body 1, a running gear 2 that supports and runs on the vehicle body 1, and a prime mover that drives the running gear 2, wherein the running gear 2 has a pair of left and right crawler devices 2a, and the crawler devices 2a have a drive wheel 2a1 driven by the prime mover, a fixed idler wheel 2a2, a movable idler wheel 2a3, and an endless track body 2a4 wound around the drive wheel 2a1, the fixed idler wheel 2a2, and the movable idler wheel 2a3, wherein the relative positional relationship between the drive wheel 2a1, the fixed idler wheel 2a2, and the movable idler wheel 2a3 changes when external pressure is applied to all or part of these wheels from the outside of the endless track body 2a4.

Description

Technical Field

[0001] The present invention relates to a work vehicle equipped with a crawler that enables various operations such as tilling.

Background Art

[0002] Conventionally, in a walking type management machine in which one traveling device is provided below a gear case provided at the center of the machine body, a rotary tiller is attached to the rear thereof, a handle rod is erected upward and rearward from the upper side of the gear case, and an operator walking behind the machine body holds the rear end portion of the handle rod for steering operation. The traveling device includes a drive idler wheel attached to the lower end portion of a traveling transmission case protruding downward from the gear case, a plurality of fixed idler wheels located on the ground contact side, and an adjusting idler wheel attached above and in front of the fixed idler wheel arranged at the foremost position. A crawler belt is wound around these to form a crawler traveling device having a hull shape in side view. The adjusting idler wheel is configured to be movable and fixed upward and forward or downward and rearward at the same angle as the inclination angle (θ) in front of the crawler traveling device. A walking type management machine configured as such is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a work vehicle, the tension bolt for adjusting the tension of the crawler belt is attached at the same angle as the inclination angle θ in front of the crawler traveling device, and the tension can be adjusted without changing the inclination angle θ by moving and fixing the adjusting idler wheel along the inclination. However, it is necessary to operate the tension bolt one by one, and there is a problem that it is too troublesome when exceeding steps or the like.

[0005] This invention aims to provide a work vehicle that can automatically and appropriately handle obstacles such as steps, taking into consideration the problems of conventional work vehicles. [Means for solving the problem]

[0006] The first invention is, The vehicle comprises a vehicle body 1, a running gear 2 that supports and moves the vehicle body 1, and a prime mover 3 that drives the running gear 2. The aforementioned running gear 2 has a pair of left and right crawler devices 2a and 2b. The crawler devices 2a and 2b each have a drive wheel 2a1 driven by the prime mover 3, a fixed wheel 2a2, a movable wheel 2a3, and an endless track 2a4 wound around the drive wheel 2a1, the fixed wheel 2a2, and the movable wheel 2a3. The work vehicle is characterized in that the relative positional relationship between the drive wheels 2a1, fixed wheels 2a2, and movable wheels 2a3 changes when external pressure is applied to all or part of these wheels from the outside of the continuous track body 2a4.

[0007] The second aspect of the present invention is: The crawler device 2a has a running frame 2a5 fixed to the lower part of the vehicle body 1, a fixing plate 2a6 is fixed to the running frame 2a5, and two fixed wheels 2a2 are rotatably connected to the lower part of the fixing plate 2a6. The first work vehicle of the present invention is characterized in which the two movable road wheels 2a3 are connected to the running frame 2a5 via a relative position change mechanism 2a7.

[0008] The third invention is, The relative position changing mechanism 2a7 includes a rotating plate 2a71 rotatably supported on a pivot point 2a51 at the front of the travel frame 2a5, an operating plate 2a72 rotatably connected at one end to the rotating plate 2a71 at a predetermined distance from the pivot point 2a51, a rod 2a73 to which the other end of the operating plate 2a72 is connected, and a biasing means attached to the travel frame 2a5 that constantly biases the rod 2a73 toward the rotating plate 2a71. A second work vehicle of the present invention, wherein one of the movable wheels 2a3 is rotatably connected to one end of the rotating plate 2a71, and the other movable wheel 2a3 is rotatably connected to the other end of the rotating plate 2a71.

[0009] The fourth aspect of the present invention is: The third work vehicle of the present invention is such that the direction in which the biasing means biases the rod 2a73 is opposite to the direction of the force that the rod 2a73 receives from the working plate 2a72 which begins to rotate in response to the external pressure.

[0010] The fifth aspect of the present invention is: The pivot point 2a51 of the rotating plate 2a71 is located below the position drawn by a straight line L connecting the centers of the front movable wheel 2a3 and the rear movable wheel 2a3, and the pivot point 2a51 of the rotating plate 2a71 is configured to be close to the front movable wheel 2a3 and close to the rear movable wheel 2a3. This is a fourth work vehicle of the present invention.

[0011] The sixth aspect of the present invention is A fifth work vehicle of the present invention, wherein a hole 2a713 is formed between the pivot point 2a51 of the rotating plate 2a71 and the rearward movable road wheel 2a3, and above the line R connecting their centers, to which one end of the working plate 2a72 is connected in order to limit the rotational range of the rotating plate 2a71.

[0012] The seventh aspect of the present invention is The prime mover 3 is an electric motor, and the drive source for the prime mover 3 is located at the front of the vehicle body 1. The sixth work vehicle of the present invention is characterized in that the two movable road wheels 2a3 are positioned towards the front of the vehicle body 1, and the drive wheel 2a1 and the two fixed road wheels 2a2 are positioned towards the rear of the vehicle body 1.

[0013] The eighth aspect of the present invention is A plate 1a1 is horizontally disposed at the upper part of the rear portion of the body frame of the body 1. The central portion 1a11 of the plate 1a1 is formed higher than the left and right ends. Brackets 1a2 are erected respectively from the left and right ends, and holders 6 for holding the motor shaft 8 are respectively attached to the brackets 1a2. It is the seventh working vehicle of the present invention.

Effect of the Invention

[0014] According to the present invention, when an external force acts on the wheels due to a step or the like, the relative positional relationship between the wheels changes, so that the impact on the machine body can be suppressed.

Brief Explanation of the Drawings

[0015] [Figure 1] Left side view of the working vehicle according to the embodiment of the present invention with a tiller attached [Figure 2] Perspective view of the same working vehicle with the tiller and one of the endless track bodies removed [Figure 3] Partial enlarged view of FIG. 1 [Figure 4] Perspective view showing a part of the relative position changing mechanism of the same working vehicle [Figure 5] Perspective view of the rotating plate of the relative position changing mechanism of the same working vehicle [Figure 6] Plan view of the same rotating plate [Figure 7] (A), (B), (C) Operation transition diagrams for explaining the operation of the same working vehicle [Figure 8] Left side view (No. 1) for explaining the operation of the same working vehicle [Figure 9] Left side view (No. 2) for explaining the operation of the same working vehicle [Figure 10] Left side view (No. 3) for explaining the operation of the same working vehicle [Figure 11] Left side view (No. 4) for explaining the operation of the same working vehicle [Figure 12] Perspective view of the same working vehicle with one of the endless track bodies removed [Figure 13] Schematic cross-sectional view of the same working vehicle with the endless track bodies removed [Figure 14] A perspective view of a portion of the body frame of the work vehicle. [Figure 15] Cross-sectional view of the drive sprocket of the work vehicle. [Figure 16] Perspective view of the holder on the work vehicle. [Figure 17] Perspective view of the holder on the work vehicle. [Figure 18] Cross-sectional view of the holder on the work vehicle. [Figure 19] Perspective view of the joint of the work vehicle. [Figure 20] A perspective view of the joint of the same work vehicle from a different angle. [Figure 21] Cross-sectional view of the joint of the work vehicle. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described in detail below with reference to the drawings.

[0017] Figure 1 is a side view of a work vehicle according to an embodiment of the present invention with a tiller 5 attached to the rear as an example of a work machine; Figure 2 is a perspective view of the same work vehicle with the tiller 5 and one of the track units 2a4 omitted; and Figure 3 is a partially enlarged view of the same work vehicle. Hereafter, the front and rear and left and right will be defined as the direction of travel of the work vehicle.

[0018] The work vehicle according to this embodiment comprises a vehicle body 1, a traveling device 2 that supports and moves the vehicle body 1, a prime mover 3 that drives the traveling device 2, and further comprises a relative position changing mechanism 2a7.

[0019] As shown in Figures 1 to 3, the continuous track body 2a4 is wound around the envelope of the drive wheel 2a1, two movable wheels 2a3, and two fixed wheels 2a2, and maintains its shape. The two movable wheels 2a3 are rotatably mounted on a rotating plate 2a71 (see Figures 5 and 6). The pivot point 2a51 of the rotating plate 2a71 is located below the position drawn by a straight line L connecting the centers of the front movable wheel 2a31 and the rear movable wheel 2a32. The pivot point 2a51 of the rotating plate 2a71 is configured such that the distance to the rear movable wheel 2a32 is longer than the distance to the front movable wheel 2a31. This pivot point 2a51 is rotatably connected to a plate part 2a52, which is part of the running frame 2a5, via a pin, as will be described later.

[0020] A hole 2a713 is provided between the pivot point 2a51 of the rotating plate 2a71 and the rear movable road wheel 2a32, and above the line R connecting their centers, to limit the rotational range of the rotating plate 2a71. The rotational range of the movable road wheel 2a3 is limited by a tube 2a75 (see Figure 4) fixed to and protruding from the running frame 2a5, a rod 2a73 sliding inside it, and an action plate 2a72 connecting the hole 2a713 of the rotating plate 2a71 and the rod 2a73. A spring 2a74 is provided between the rod 2a73 and the tube 2a75 as a biasing means, and the spring 2a74 expands and contracts according to the center of gravity of the machine. This spring 2a74 also acts as a suspension during normal operation, running, and when going over steps, and plays a significant role in absorbing shocks to the control board and battery.

[0021] The sliding direction of the rod 2a73 is set to be almost parallel to the tangential direction of the start of rotation of the movable road wheel 2a3 (2a32), and it effectively receives the force acting on the movable road wheel 2a3. That is, the direction in which the biasing spring 2a74 biases the rod 2a73 is opposite to the direction of the force that the rod 2a73 receives from the working plate 2a72, which starts to rotate under external pressure. This configuration allows for adaptation to changes in working posture as shown in Figure 7, as well as adaptation to crossing over embankments.

[0022] The inner diameter of the spring 2a74 is positioned to fit along the outer diameter of the tube 2a75, acting as a guide for the smooth expansion and contraction of the spring 2a74. In the illustrated embodiment, the upper limit of the rotation range of the movable road wheel is restricted when the spring 2a74 is in its most compressed state.

[0023] The bottom surface of tube 2a75 abuts against the seating surface 2a73Z formed on rod 2a73, thereby preventing the spring from being fully compressed and limiting the rotation range of the movable road wheel. In other words, even if rod 2a73 protrudes upward, the seating surface 2a73Z abuts against tube 2a75, stopping the movement of rod 2a73.

[0024] The rod 2a73 is provided with a seating surface to receive the spring 2a74.

[0025] A plate component 2a52 is formed to hang down from a portion of the front of the running frame 2a5, and a hole corresponding to the pivot point 2a51 is formed in the lower end of the component 2a52, and the rotating plate 2a71 is rotatably supported via a pin. That is, the hole in the rotating plate 2a71 and the hole in the plate component 2a52 are aligned and connected by pinning at the pivot point 2a51. By providing the plate component 2a52 in this way, the assembly and tensioning of the continuous track body 2a4 can be made easier.

[0026] In a typical configuration where tension is applied to a continuous track system 2a4, this is done by extending one road wheel or idler. However, in the work vehicle of this embodiment, tension is applied by simultaneously extending two rotating movable road wheels 2a3, thereby reducing the extension distance compared to conventional designs and allowing for the construction of a more compact machine.

[0027] Next, the operation of the work vehicle in this embodiment will be described.

[0028] During normal driving or operation, as shown in Figures 7(A) and 8, the three road wheels—the rear movable road wheel 2a32 and the two fixed road wheels 2a2, 2a2—are in contact with the ground simultaneously. This configuration increases the contact length and stabilizes straight-line movement.

[0029] During normal driving or operation, the rear movable road wheel 2a32 moves in accordance with the ground via the action plate 2a72 and rotation plate 2a71, powered by the spring 2a74, thereby improving the machine's grip even on uneven terrain.

[0030] During turns, as shown in Figures 7(B) and 9, the center of gravity of the machine is moved forward by methods such as shifting weights, and the machine is tilted forward to lift the implement such as the tiller 5, so that the only points of contact with the ground are the rear movable wheel 2a32 and the front fixed wheel 2a2. Furthermore, as shown in Figures 7(C) and 10, by tilting forward, the points of contact with the ground become the front movable wheel 2a31 and the rear movable wheel 2a32, shortening the ground contact length and enabling turns with reduced turning space without disturbing the field.

[0031] In other words, during rotation, the contact points of the continuous track 2a4 gradually shift from three wheels to two wheels.

[0032] In this way, during turns, the shape of the continuous track system 2a4 is variably deformed by the force of the spring 2a74 during the shift in the center of gravity, thereby reducing the impact on the aircraft and allowing for smooth changes in attitude.

[0033] In other words, as shown in Figures 7(B), 9, 7(C), and 10, when a large external pressure is applied to the rear movable road wheel 2a32 from the outside of the track body 2a4, the rotating plate 2a71 begins to rotate counterclockwise around the pivot point 2a51. Consequently, the action plate 2a72 moves upward. As the action plate 2a72 moves upward, the connected rod 2a73 moves upward against the biasing force of the spring 2a74.

[0034] During this process, the shape of the continuous track 2a4 deforms to match the turning, but the stopper function of the tube 2a75 and spring 2a74 prevents the rear movable road wheel 2a32 from exceeding the line connecting the front movable road wheel 2a31 and the front fixed road wheel 2a2. In other words, by preventing the rear movable road wheel 2a32 from recessing too far inward, the configuration ensures stable attitude changes, maintains ground contact length, and prevents the continuous track 2a4 from coming off.

[0035] Here, considering the relationship between the pivot point 2a51 of the rotating plate 2a71 and the mounting position of the road wheels, it is desirable to have a configuration in which the change in the length of the envelope of each road wheel 2a1, 2a2, and 2a3 is kept within 5 mm. Also, when the movable road wheels 2a31 and 2a32 move, the length of the envelope in the working position and the turning position becomes slightly shorter, so the tension of the continuous track body 2a4 loosens slightly in the intermediate position, and the rotation of the rotating plate 2a71 is performed smoothly.

[0036] Figure 11 shows how, when there is a step or slope in front, the movable road wheel 2a32 retracts, allowing the track body 2a4 to smoothly climb over it.

[0037] The center of gravity of the machine is typically located between the front and rear fixed road wheels 2a2. The total weight of the machine is supported by the running frame 2a5 and the main frame of the body 1 through the left and right fixed road wheels 2a2 and the fixing plates 2a6 to which the 2a2 are attached, and no load is directly applied to the motor shaft of the drive wheel 2a1.

[0038] Figure 12 is a perspective view of the work vehicle of this embodiment with one of the track units 2a4 removed, and Figure 13 is a schematic cross-sectional view thereof.

[0039] Here, 1a is the body frame of the vehicle body 1, a component as shown in Figure 14. A plate 1a1 is horizontally positioned at the rear of the frame, serving as a waterproofing element to prevent water from entering the motor and electrical components from below. This component ensures stable operation and a structure that is less prone to breakage even under load. The left and right motors are mounted on the left and right sides of this plate 1a1 (see Figure 15), making them easy to attach and detach, and the shape does not interfere with the sliding of the weights or the movement of the cylinders. The large gap between the motor and the plate 1a1 prevents heat buildup, allowing for continuous operation (see Figure 15). Furthermore, the motor and sprocket can be assembled concentrically.

[0040] Plate 1a1 has a raised central section 1a11, which prevents interference with the cylinder located below it. It also does not interfere with the weight used for shifting the center of gravity, which is located below it.

[0041] Brackets 1a2, 1a2 are erected on both the left and right ends of plate 1a1, respectively.

[0042] Each of the brackets 1a2 has four holders 6 fixed to it with bolts. The motor shaft 8 of the motor is held by these holders 6, as will be described later.

[0043] As shown in Figures 15 to 18, the inner diameter of the holder 6 on the motor shaft 8 side is such that it fits onto the outer part of the motor shaft 8, and the motor shaft 8 and the holder 6 can be assembled concentrically. Furthermore, since the motor holder 6 is provided by press-fitting it onto the outer part of the motor shaft 8, no bending force is directly generated on the motor shaft 8 in relation to the force that tensions the continuous track body 2a4 described above.

[0044] In other words, the inner diameter of the holder 6 furthest from the motor shaft 8 has a length and diameter that can accommodate two or more bearings, allowing the holder 6, rather than the motor shaft 8, to receive the load from the track body 2a4.

[0045] As shown in Figure 18, a groove 6a for inserting a retaining ring is provided on the outer side of the machine body with an inner diameter 6b where the bearing is attached by the holder 6.

[0046] As shown in Figure 15, a joint 7 is provided to connect the motor shaft 8 to the drive sprocket 9. As shown in Figures 19, 20, and 21, this joint 7 is constructed by welding two members together. One cylinder 71 is shaped for the motor shaft 8, and the other cylinder 72 is shaped for the drive sprocket 9. The inner diameter of the cylinder 71 is sized to match the motor shaft 8, and a groove 71a is formed therein for a key material that transmits the rotation of the motor shaft 8. On the other hand, a tap 72a is formed on the outer end face of the cylinder 72 to prevent the drive sprocket 9 from coming out.

[0047] As shown in Figure 21, from the part of the joint 7 where the other cylinder 72 is inserted into one cylinder 71 to the motor shaft 8 side, the inner diameter is slightly enlarged for a distance of a few millimeters, creating a relief groove 71b for inner diameter polishing.

[0048] Furthermore, as shown in Figure 15, a spacer collar member 10 is provided to prevent it from entering the inside of the drive sprocket 9.

[0049] The implement to be mounted on the work vehicle of the present invention is not limited to the tiller described above, but may be any other implement. Furthermore, the prime mover is not limited to an electric motor. [Industrial applicability]

[0050] This invention is a work vehicle that can automatically adapt to and appropriately navigate over obstacles such as steps, making it ideal for tilling and other similar tasks. [Explanation of symbols]

[0051] 1. Vehicle body 1a Vehicle frame 1a1 plate 1a11 central part 1a2 bracket 2. Traveling device 2a Left crawler device 2a1 Drive wheel 2a2 Fixed road wheels 2a3 Movable road wheels 2a31 Forward movable road wheel 2a32 Rear movable road wheel 2a4 Track body 2a5 Running frame 2a51 Rotating fulcrum 2a52 plate parts 2a6 Fixed plate 2a7 Relative position change mechanism 2a71 Rotating Plate 2a711 one end 2a712 Other end 2a713 hole 2a72 Working plate 2a73 Rod 2a74 Biasing means (spring) 2a75 Tube 2b Right crawler device 3. Engine 3a Left motor 3b Right motor 4. Power source (battery) 5 Work equipment (tiller) 6 holders 6a groove 6b Inner diameter 7 joints 71 One-sided cylinder 71a, 71b groove 72 The cylinder 72a Tap 73 gaps 8 motor shafts 9 Drive sprocket 10 Color components

Claims

1. The vehicle comprises a vehicle body, a running gear that supports the vehicle body and allows it to move, and a prime mover that drives the running gear. The aforementioned traveling device has a pair of left and right crawler devices, The crawler device comprises a drive wheel driven by the prime mover, a fixed wheel, a movable wheel, and an endless track wrapped around the drive wheel, the fixed wheel, and the movable wheel. A work vehicle characterized in that the relative positional relationship between the drive wheels, fixed wheels, and movable wheels changes when external pressure is applied to all or part of these wheels from outside the track body.

2. The crawler device has a running frame fixed to the lower part of the vehicle body, a fixing plate fixed to the running frame, and two fixed wheels rotatably connected to the lower part of the fixing plate. The work vehicle according to claim 1, wherein the two movable road wheels are connected to the running frame via a relative position change mechanism.

3. The relative position changing mechanism comprises a rotating plate pivotably supported at a pivot point at the front of the travel frame, an operating plate rotatably connected at one end to the rotating plate at a predetermined distance from the pivot point, a rod to which the other end of the operating plate is connected, and a biasing means attached to the travel frame that constantly biases the rod toward the rotating plate. The work vehicle according to claim 2, wherein one of the movable wheels is rotatably connected to one end of the rotating plate, and the other movable wheel is rotatably connected to the other end of the rotating plate.

4. The work vehicle according to claim 3, wherein the direction in which the biasing means biases the rod is opposite to the direction of the force received by the rod from the working plate which begins to rotate upon receiving the external pressure.

5. The pivot point of the rotating plate is located below the position drawn by a straight line connecting the centers of the front movable wheel and the rear movable wheel, and the pivot point of the rotating plate is configured to be close to the front movable wheel and close to the rear movable wheel.

6. The work vehicle according to claim 5, wherein a hole is formed between the pivot point of the rotating plate and the rearward movable road wheel, and above the line connecting their centers, to which one end of the working plate is connected for restricting the rotational range of the rotating plate.

7. The prime mover is an electric motor, and the power source for the prime mover is located at the front of the vehicle body. The work vehicle according to claim 6, wherein the two movable road wheels are positioned towards the front of the vehicle body, and the drive wheel and the two fixed road wheels are positioned towards the rear of the vehicle body.

8. A plate is horizontally positioned on the upper rear portion of the vehicle frame of the vehicle body, the central part of the plate is formed to be higher than both the left and right ends, brackets are erected from both the left and right ends, and holders for holding motor shafts are attached to each of the brackets, as described in claim 7.

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