Work vehicles

Abstract

To provide a work vehicle that has no forward / backward movement lever and can stop transmission of driving to a PTO shaft at low cost when stopping or moving backward.SOLUTION: A work vehicle (1) has a forward movement pedal (202) and a backward movement pedal (203) and no forward / backward movement lever, by including a switch (213) for determining whether the forward movement pedal (202) is operated and a PTO clutch (221) for switching to non-transmission of power when the forward movement pedal (202) is not operated based upon a determination result of the switch (213), so as to determine that the work vehicle (1) moves forward, stops, or moves backward by the use of the relatively low-cost switch without including an expensive vehicle speed sensor, thereby stopping transmission of driving to a PTO shaft while the vehicle stops or moves backward.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a work vehicle such as a tractor, a seedling transplanter, or a lawnmower. [Background technology]

[0002] BACKGROUND ART The technology described in Patent Document 1 is known for work vehicles such as tractors and seedling transplanters that perform work by transmitting drive to a work machine via a PTO (Power Take Off) shaft. Patent Document 1 describes a technology in which a work vehicle that spreads snow-melting agent can switch between forward and reverse using a forward / reverse lever, and the rotation of the drive wheels can be detected by a rotation speed sensor.When the vehicle is stopped (when the rotation speed of the drive wheels is zero) or when the forward / reverse lever is operated to the reverse side, the transmission of drive to the PTO shaft is restricted, so that drive is transmitted to the PTO shaft only when the vehicle is moving forward, thereby operating the work equipment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-24330 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology described in Patent Document 1, a forward / reverse lever is used to determine whether to operate the vehicle in reverse, but some work vehicles do not have a forward / reverse lever and instead use forward and reverse pedals to operate the vehicle in forward and reverse, and this cannot be realized in a configuration that does not have a forward / reverse lever. Furthermore, in work vehicles that can move forward and backward, it is important to display the engine RPM in relation to the work, but the vehicle speed, which fluctuates due to gear changes and clutch engagement and disengagement, is less important to display than the engine RPM. Therefore, some work vehicles do not have a function to display vehicle speed, and some work vehicles do not have a vehicle speed sensor that detects axle rotation. Therefore, the configuration of Patent Document 1, which detects vehicle speed and regulates the transmission of drive to the PTO shaft, cannot be implemented in work vehicles that do not have a relatively expensive vehicle speed sensor.

[0005] The present invention has as its technical object the provision of a work vehicle that does not have a forward / reverse lever and that can stop the vehicle at low cost or stop the transmission of drive to the PTO shaft when reversing. [Means for solving the problem]

[0006] The above-mentioned problems of the present invention are solved by the following means. The invention described in claim 1 includes a traveling body (1a) having a working implement (18), an engine (E) supported on the traveling body (1a), a PTO shaft (141) that transmits the power of the engine (E) to the working implement (18), a forward pedal (202) that is operated when moving the traveling body (1a) forward, a reverse pedal (203) that is operated when moving the traveling body (1a) backward, an interlocking part (211) that moves in conjunction with the operation of the forward pedal (202), and a PTO shaft (141) that transmits the power of the engine (E) to the working implement (18). a switch (213) that is switched on and off by the interlocking part (211) that moves in response to the operation of the forward pedal (202), thereby determining whether or not the forward pedal (202) is being operated; and a PTO clutch (221) that is disposed in a power transmission path from the engine (E) to the PTO shaft (141) and switches between transmission and non-transmission of power, and the PTO clutch (221) switches to non-transmission of power when the forward pedal (202) is not being operated based on the determination result of the switch (213). a second interlocking part (212) that moves in conjunction with the operation of the forward pedal (202) and the reverse pedal (203); a second switch (214) that switches on and off depending on whether the forward pedal (202) and the reverse pedal (203) are not operated or whether either the forward pedal (202) or the reverse pedal (203) is operated; the PTO clutch (221) that switches power transmission to non-transmission based on the determination result of the switch (213) and also switches power transmission to non-transmission even when the forward pedal (202) and the reverse pedal (203) are not operated based on the determination result of the second switch (214); and an interlocking shaft (204) that rotates in conjunction with the operation of the forward pedal (202) and the reverse pedal (203). Equipped with The interlocking portion (211) and the second interlocking portion (212) are arranged adjacent to each other along the axial direction of the interlocking shaft (204), and the switch (213) and the second switch (214) are arranged adjacent to each other corresponding to the interlocking portion (211) and the second interlocking portion (212). The work vehicle (1) is characterized by the above. [Effects of the Invention]

[0007] According to the invention of claim 1, in a work vehicle (1) having a forward pedal (202) and a reverse pedal (203) but no forward / reverse lever, it is possible to determine whether the work vehicle (1) is moving forward, stopped, or in reverse using a relatively low-cost switch, without having to provide an expensive vehicle speed sensor, and to stop the transmission of drive to the PTO shaft when the vehicle is stopped or in reverse. Also, claim 1 According to the described invention 、 The second switch (214) can determine a neutral state in which neither the forward pedal (202) nor the reverse pedal (203) of the work vehicle (1) is operated, and can stop the transmission of drive to the PTO shaft when the work vehicle (1) is in the neutral state. Furthermore, claim 1 According to the described invention 、 By arranging the interlocking part (211) and the second interlocking part (212) next to each other and arranging the switch (213) and the second switch (214) correspondingly, the interlocking part (211), the second interlocking part (212), the switch (213), and the second switch (214) can be installed compactly, thereby saving space overall. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram of the main parts of the engine, main transmission, and pedals according to the embodiment. [Figure 3] FIG. 3 is a perspective view seen from the direction of arrow III in FIG. [Figure 4] FIG. 4 is an enlarged view of the switch portion of FIG. [Figure 5] FIG. 5 is an explanatory diagram of the switch portion for detecting forward movement. [Figure 6] FIG. 6 is an explanatory diagram of the switch portion for detecting the neutral position. [Figure 7] FIG. 7 is a perspective view of the switch and the mounting plate. [Figure 8] FIG. 8 is an explanatory diagram of the mounting hole portion of the mounting plate. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment. In FIG. 1, a snow removal tractor 1, as an example of a work vehicle of the present invention, is equipped with front wheels 2, 2 and rear wheels 3, 3 at the front and rear of a traveling body 1a. The rotational power of an engine E mounted in an engine compartment 4 at the front of the traveling body is appropriately reduced by a transmission in a transmission case 5 and transmitted to the front wheels 2, 2 and the rear wheels 3, 3. The engine compartment 4 is covered by a hood 6. A work implement, such as a chemical sprayer 18 that sprays chemicals (e.g., snow-melting agent, antifreeze agent) on the road surface behind the tractor 1, is mounted at the rear of the tractor 1, and power is transmitted to the work implement via a rear PTO shaft 141. A snow removal brush 26, as an example of a work implement, is mounted at the front of the body. The snow removal brush 26 is a rotating brush that blows snow off the road surface to the side. The snow removal brush 26 is driven by power transmitted via a mid-PTO shaft 146. In this specification, the left and right sides of the tractor 1 when viewed in the forward direction are referred to as the left and right sides, respectively, and the forward direction is referred to as the front side, and the backward direction is referred to as the rear side.

[0010] A cabin 7 is supported on the upper part of the traveling vehicle body 1a. Inside the cabin 7, a driver's seat 8 is disposed above the transmission case 5, and a steering wheel 10, a parking brake (not shown), and the like are disposed in front of the driver's seat 8. Also disposed in front of the driver's seat 8 are a display panel for a speedometer (not shown), various operation switches (not shown), and the like. Disposed below and in front of the driver's seat 8 are travel operating devices such as a brake pedal 12 and an accelerator pedal 13 having a forward pedal and a reverse pedal.

[0011] In Figure 1, a hydraulic cylinder case 14 is provided above the rear of the transmission case 5, and lift arms 15, 15 are pivotally attached to both the left and right sides of this hydraulic cylinder case 14. Lift rods 17, 17 are interposed and connected between the lift arms 15, 15 and lower links 16, 16, and a chemical sprayer 18, an example of a work machine, is connected to the rear of the lower links 16, 16.

[0012] When hydraulic oil is supplied to the hydraulic cylinder 14a housed in the hydraulic cylinder case 14, the lift arms 15, 15 are rotated upward, and the work machine (pesticide sprayer) 18 is raised via the lift rod 17, lower link 16, etc. Conversely, when the hydraulic oil in the hydraulic cylinder 14a is discharged into the transmission case 5, which also serves as a hydraulic tank, the lift arms 15, 15 are lowered. A position sensor SN1 is disposed at the base end of the lift arm 15 to detect the tilt angle of the lift arm 15, that is, the elevation of the work machine 18.

[0013] In addition, the working machines attached to the rear of the traveling body 1a, i.e., the working machines to which drive is transmitted from the rear PTO shaft 141, include agricultural working machines such as rotary tillers and plows for agricultural work, seed sowing machines, seedling transplanters, fertilizer spreaders, and pesticide spreaders, in addition to pesticide sprayers. In addition, as a work implement attached to the front of the traveling body 1a, i.e., a work implement to which drive is transmitted from the mid-PTO shaft 146, in addition to the snow removal brush 26, for example, a lawn mower or a loader capable of storing and transporting samples, grass, soil, crops, etc. in baguettes can be used.

[0014] (Explanation of the pedals, engine, and main transmission configuration) FIG. 2 is an explanatory diagram of the main parts of the engine, main transmission, and pedals according to the embodiment. FIG. 3 is a perspective view seen from the direction of arrow III in FIG. FIG. 4 is an enlarged view of the switch portion of FIG. FIG. 5 is an explanatory diagram of the switch portion for detecting forward movement. FIG. 6 is an explanatory diagram of the switch portion for detecting the neutral position. FIG. 7 is a perspective view of the switch and the mounting plate. FIG. 8 is an explanatory diagram of the mounting hole portion of the mounting plate.

[0015] 2 and 3, in the tractor 1 of the embodiment, an HST (Hydraulic Static Transmission) 201, which is an example of a main transmission, is disposed at the rear of the engine E. Note that in Figs. 2 to 8, parts and components that are not relevant to the description of the invention are not shown. A forward pedal 202 and a reverse pedal 203 are disposed on the right side of the HST 201. The forward pedal 202 is a member that the driver steps on with his foot to operate the tractor 1 forward. The reverse pedal 203 is a member that the driver steps on with his foot to operate the tractor 1 in reverse. A base end of the reverse pedal 203 is supported on the right end of an interlocking shaft 204. The interlocking shaft 204 passes through the HST 201 in the left-right direction and is rotatably supported by the HST 201.

[0016] In Figure 2, the base end of the forward movement pedal 202 is supported by the right end of the interlocking sleeve 206. The interlocking sleeve 206 is configured in a cylindrical shape extending in the left-right direction, with the interlocking shaft 204 passing through its interior. One end of a forward movement link arm 207 is rotatably connected to the left end of the interlocking sleeve 206. The other end of the forward movement link arm 207 is connected to a trunnion shaft 208 of the HST 201.

[0017] The trunnion shaft 208 is a known component for changing the tilt angle of the swash plate (not shown) inside the HST 201, and by controlling the tilt angle of the trunnion shaft 208, it is possible to move forward (forward rotation) or backward (reverse rotation) in a stepless manner, and to change speeds (change the rotational speed). One end of a reverse link arm 209 is rotatably connected to the interlocking shaft 204 at a position to the left of the left end of the interlocking sleeve 206. The other end of the reverse link arm 209 is connected to a trunnion shaft 208 of the HST 201.

[0018] 3 to 6, an advance detection cam 211 as an example of an interlocking portion and a neutral detection cam 212 as an example of a second interlocking portion are disposed on the left end of the interlocking shaft 204. The advance detection cam 211 and the neutral detection cam 212 are disposed adjacent to each other in the axial direction of the interlocking shaft 204. Therefore, compared to when the two cams 211, 212 are disposed apart, it is possible to save installation space. In FIG. 5, the forward movement detection cam 211 of the embodiment is made up of a substantially fan-shaped plate member, and the diameter of the upper part 211a from the interlocking shaft 204 is formed to be larger than that of the lower part 211b.

[0019] 6, the neutral detection cam 212 of the embodiment is formed of a substantially fan-shaped plate member, and the upper portion 212a and the lower portion 212b are formed to have the same diameter from the interlocking shaft 204, while the intermediate portion 212c between the upper portion 212a and the lower portion 212b is formed to have a smaller diameter than the upper portion 212a and the lower portion 212b. Therefore, the neutral detection cam 212 has a fan shape with the intermediate portion 212c recessed in the circumferential direction of the neutral detection cam 212.

[0020] In front of each of the cams 211 and 212, a forward movement detection switch 213 as an example of a switch and a neutral position detection switch 214 as an example of a second switch are arranged. The forward movement detection switch 213 and the neutral movement detection switch 214 correspond to the forward movement detection cam 211 and the neutral movement detection cam 212, and are arranged adjacent to each other in the axial direction of the interlocking shaft 204. The forward movement detection switch 213 has a box-shaped switch body 213a. A contact portion 213b that protrudes rearward is provided at the lower part of the rear surface of the switch body 213a. A forward movement leaf spring portion 213c is disposed on the rear side of the switch body 213a, and the upper end of the forward movement leaf spring portion 213c is supported by the switch body 213a. A forward movement cam follower 213d that can come into contact with the front surface (outer peripheral surface) of the forward movement detection cam 211 is provided at the lower end of the forward movement leaf spring portion 213c.

[0021] The forward movement cam follower 213d comes into contact with the outer peripheral surface of the forward movement detection cam 211 due to the elastic force of the forward movement leaf spring portion 213c. In this embodiment, the positions, shapes, and sizes of the various components are set so that when the forward movement cam follower 213d is in contact with the small-diameter lower portion 211b, the forward movement leaf spring portion 213c does not come into contact with the contact portion 213b, and when the forward movement cam follower 213d is in contact with the large-diameter upper portion 211a, the forward movement leaf spring portion 213c comes into contact with the contact portion 213b. When the forward movement leaf spring portion 213c comes into contact with the contact portion 213b, electricity is conducted, turning the forward movement detection switch 213 on, and when the forward movement leaf spring portion 213c is not in contact with the contact portion 213b, the switch is off. Furthermore, the positions of the various components are set so that the forward cam follower 213d comes into contact with the boundary 211c between the upper part 211a and the lower part 211b when the forward pedal 202 and the reverse pedal 203 are not depressed (neutral state, no drive force is transmitted). The boundary 211c has the same diameter as the upper part 211a and a larger diameter than the lower part 211b.

[0022] The neutral detection switch 214 is configured similarly to the forward movement detection switch 213, and includes a switch body 214a, a contact portion 214b, a neutral leaf spring portion 214c, and a neutral cam follower 214d. The neutral cam follower 214d contacts the outer peripheral surface of the neutral detection cam 212 due to the elastic force of the neutral leaf spring portion 214c. In this embodiment, the positions, shapes, and sizes of the respective components are set so that when the neutral cam follower 214d is in contact with the small-diameter intermediate portion 212c, the neutral leaf spring portion 214c does not contact the contact portion 214b, and when the neutral cam follower 214d is in contact with the large-diameter upper portion 212a or lower portion 212b, the neutral leaf spring portion 214c contacts the contact portion 214b. When the neutral leaf spring portion 214c and the contact portion 214b come into contact, electricity is conducted, turning the neutral detection switch 214 on, and when the neutral leaf spring portion 214c and the contact portion 214b are not in contact, the switch is off. Furthermore, the positions of the various members are set so that the neutral cam follower 214d comes into contact with the intermediate portion 212c when the forward pedal 202 and the reverse pedal 203 are not depressed (neutral state, non-power transmission state).

[0023] 4 to 8, the forward movement detection switch 213 and the neutral position detection switch 214 are supported on the left side wall of the HST 201 via a mounting plate 216. The mounting plate 216 has a plate-shaped switch support portion 216a, a connecting portion 216b extending rightward from the lower end of the switch support portion 216a, and a mounted portion 216c extending rearward from the right end of the connecting portion 216b.

[0024] The switch support portion 216a supports the forward movement detection switch 213 and the neutral position detection switch 214. In the embodiment, the forward movement detection switch 213 and the neutral position detection switch 214 are configured similarly and are arranged adjacent to each other, and compared to when the two switches have different configurations or are arranged at distant positions, the two switches 213, 214 can be supported by a single mounting plate 216, which simplifies the configuration, reduces costs, and saves installation space.

[0025] A pair of mounting holes 216d are formed in the mounting portion 216c, one at the front and one at the rear. The mounting plate 216 is supported on the left wall of the HST 201 by screws 217 that pass through the mounting holes 216d. As shown in FIG. 8, the mounting holes 216d in this embodiment are configured as arc-shaped elongated holes that follow an arc centered on the interlocking shaft 204. This makes it easy to adjust the positional relationship around the interlocking shaft 204 when fine-tuning the positions of the switches 213, 214.

[0026] (Explanation of pedal operation and movement of each part) 2 to 6, in the tractor 1 of the embodiment, when neither the forward pedal 202 nor the reverse pedal 203 is depressed, each cam follower 213d, 214d contacts the boundary portion 211c and the middle portion 212c of each cam 211, 212, and the forward detection switch 213 is on and the neutral detection switch 214 is off.

[0027] In Figure 2, when the forward pedal 202 is depressed, the interlocking sleeve 206 rotates in the direction indicated by the solid arrow Ya in Figure 2. As the interlocking sleeve 206 rotates, the forward link arm 207 moves in the direction indicated by the solid arrow, and the trunnion shaft 208 also rotates in the direction indicated by the solid arrow. Therefore, the HST 201 outputs a rotational speed in the forward direction that corresponds to the amount of rotation of the trunnion shaft 208. As the trunnion shaft 208 rotates, the reverse link arm 209 also moves in the direction indicated by the solid arrow, and the interlocking shaft 204 rotates in the direction indicated by the solid arrow. 3, when interlocking shaft 204 rotates in the direction of solid arrow Ya, two cams 211, 212 also rotate in the direction of solid arrow Ya. Therefore, each cam follower 213d, 214d comes into contact with the outer circumferential surface of lower portion 211b, 212b of each cam 211, 212, and both forward detection switch 213 and neutral detection switch 214 are turned off.

[0028] In Figure 2, when the reverse pedal 203 is depressed, the interlocking shaft 204 rotates in the direction indicated by the dashed arrow Yb in Figure 2. As the interlocking shaft 204 rotates, the reverse link arm 209 moves in the direction indicated by the dashed arrow Yb, and the trunnion shaft 208 also rotates in the direction indicated by the dashed arrow Yb. Therefore, the HST 201 outputs a rotational speed in the reverse direction that corresponds to the amount of rotation of the trunnion shaft 208. 3, when the interlocking shaft 204 rotates in the direction of the dashed arrow Yb, the two cams 211 and 212 also rotate in the direction of the dashed arrow Yb. Therefore, the cam followers 213d and 214d come into contact with the outer circumferential surfaces of the upper portions 211a and 212a of the cams 211 and 212, respectively, and the forward detection switch 213 and the neutral detection switch 214 are both turned on.

[0029] Therefore, in the tractor 1 of this embodiment, when the forward pedal 202 is depressed to operate the tractor for forward movement, the forward detection switch 213 is turned off, and when the reverse pedal 203 is depressed to operate the tractor for reverse movement or when the tractor is in a neutral state where neither pedal 202, 203 is operated, the forward detection switch 213 is turned on. Also, the neutral detection switch 214 is turned off in the neutral state, and is turned on when both pedals 202, 203 are operated (forward state or reverse state: non-neutral state). Therefore, based on the detection results of the forward detection switch 213 and the neutral detection switch 214, it is possible to determine whether the tractor 1 is moving forward, backward, or in neutral (whether drive is not transmitted) from the combination of on / off of the two switches 213, 214.

[0030] In the embodiment, two switches, forward detection switch 213 and neutral detection switch 214, are used, but if it is only necessary to determine whether the vehicle is moving forward, stopped, or in reverse, then neutral detection switch 214 and neutral detection cam 212 are not necessarily required. In the embodiment, by providing neutral detection switch 214 and neutral detection cam 212, it is possible to reliably detect the neutral state.

[0031] Alternatively, the upper part 212a of the neutral detection cam 212 can be made as small in diameter as the lower part 211b of the forward detection cam 211, and the neutral detection switch 214 can be used to detect whether the vehicle is in neutral, forward, or reverse, and the forward / reverse / neutral position can be determined from the combination of the detection results of the two switches 213 and 214. Furthermore, the shapes (radii of the sectors) of the cams 211 and 212 are configured to switch between on and off as described above, but are not limited to this. For example, the forward movement detection cam 211 may have a small diameter at the upper portion 211a and boundary portion 211c and a large diameter at the lower portion 211b, or the neutral detection cam 212 may have a larger diameter at the middle portion 212c than the other portions.

[0032] 3, the control unit C of the tractor 1 of this embodiment switches the PTO clutch 221 to non-transmission when the tractor is not in a forward drive state (when the tractor is in a neutral or reverse drive state) based on the detection results of the switches 213, 214, i.e., when the forward drive detection switch 213 is on or the neutral detection switch 214 is off. The PTO clutch 221 is a clutch that is disposed in the power transmission path from the engine E to the PTO shaft 141 and switches between transmission and non-transmission of power, and as this is conventionally known, detailed description thereof will be omitted. Therefore, in a tractor 1 that does not have a forward / reverse lever, a relatively expensive vehicle speed sensor is not required, and the relatively low-cost configuration of switches 213 and 214 can stop the transmission of drive to PTO shaft 141 when tractor 1 is in neutral (stopped) or in reverse. This prevents the working machine from accidentally operating when reversing or stopped, causing the pesticide to be sprayed in unintended locations. [Explanation of symbols]

[0033] 1...Work vehicle, 1a...Traveling vehicle body, 18...Work equipment, 141...PTO shaft, 202...Forward pedal, 203...reverse pedal, 204... Interlocking shaft, 211...Interlocking part, 212...second interlocking part, 213...switch, 214...second switch, 221...PTO clutch, E...Engine.

Claims

[Claim 1] a traveling vehicle body (1a) having a working machine (18); an engine (E) supported on the traveling vehicle body (1a); a PTO shaft (141) that transmits power from the engine (E) to the working machine (18); a forward pedal (202) that is operated when moving the traveling vehicle body (1a) forward; a reverse pedal (203) that is operated when the traveling vehicle body (1a) is to be moved backward; A linkage part (211) that moves in conjunction with the operation of the forward pedal (202); a switch (213) that is switched on and off by the interlocking part (211) that moves in response to the operation of the forward pedal (202), thereby determining whether the forward pedal (202) is being operated; a PTO clutch (221) disposed in a power transmission path from the engine (E) to the PTO shaft (141) for switching between power transmission and non-transmission, the PTO clutch (221) switching to non-transmission of power when the forward pedal (202) is not operated based on the determination result of the switch (213); a second interlocking part (212) that moves in conjunction with the operation of the forward pedal (202) and the reverse pedal (203); a second switch (214) that switches between on and off depending on whether the forward pedal (202) and the reverse pedal (203) are not operated or whether either the forward pedal (202) or the reverse pedal (203) is operated; the PTO clutch (221) that switches power transmission to non-transmission based on the determination result of the switch (213) and also switches power transmission to non-transmission based on the determination result of the second switch (214) even when the forward pedal (202) and the reverse pedal (203) are not operated; a linkage shaft (204) that rotates in conjunction with the operation of the forward pedal (202) and the reverse pedal (203); Equipped with The interlocking portion (211) and the second interlocking portion (212) are arranged adjacent to each other along the axial direction of the interlocking shaft (204), The switch (213) and the second switch (214) are arranged adjacent to each other in correspondence with the interlocking portion (211) and the second interlocking portion (212). A work vehicle (1) characterized in that

Images