JP2020001534A - Passenger car type work vehicle - Google Patents

Abstract

To provide a passenger car type work vehicle that is inexpensive and that can detect the amount of extension/retraction of a hydraulic cylinder with superior durability even when being used outdoors.SOLUTION: A passenger type work vehicle includes: a hydraulic cylinder capable of changing a height of a driving wheel relative to a vehicle body frame; and operation amount detection means 60 configured to detect the amount of extraction/retraction of the hydraulic cylinder. The operation amount detection means 60 includes: a screw shaft 66 mounted to move integrally with one of a first member 62 and a second member 63 which are relatively movable in accordance with extension/retraction of the hydraulic cylinder and provided with a helical blade 65 on the outer circumference of the screw shaft; a slidable member 67 mounted on the other of the first member and the second member and slidably operable to the helical blade 65 in accordance with the relative movement of the first member 62 and the second member 63 to guide the screw shaft 66 so that the screw shaft rotates; and a rotation detection sensor 68 capable of detecting the number of rotations of the screw shaft 66. The amount of extension/retraction of the hydraulic cylinder is detected based on the number of rotations detected by the rotation detection sensor 68.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a riding type work vehicle having a riding type traveling body with a plurality of traveling wheels.

  2. Description of the Related Art In a riding type work vehicle that travels while working in a field, a hydraulic cylinder having a large operating force is used to detect the amount of expansion / contraction operation of a hydraulic cylinder when performing an operation that changes the ground height of a traveling vehicle body. For this reason, there is a case where a stroke sensor having a configuration capable of performing expansion and contraction operations similar to a hydraulic cylinder is provided. Conventionally, as this type of stroke sensor, a fixed side electrode and a movable side electrode are provided in a storage case, and the expansion / contraction operation is performed based on the amount of change in capacitance that changes with the expansion / contraction operation of the hydraulic cylinder. In some cases, the amount is electrically detected (for example, see Patent Document 1).

JP 2018-63239 A

  In the above conventional configuration, the fixed side electrode and the movable side electrode need to be formed accurately in the storage case, and a capacitance detection circuit for detecting the capacitance is also required. There was a disadvantage. In addition, because of the structure that electrically detects the capacitance between the electrodes, there is a greater risk of failure when used under conditions where moisture may enter or severe vibration may be applied. When used in a car, it is disadvantageous in terms of durability.

  Therefore, it has been desired to be able to detect the amount of expansion / contraction operation of the hydraulic cylinder at a low cost and with excellent durability even when used outdoors.

  The feature configuration of the riding-type work vehicle according to the present invention includes a traveling body, a body frame, traveling wheels supported so as to be capable of changing a relative height with respect to the body frame, and a relative height of the traveling wheels with respect to the body frame. A hydraulic cylinder that can switch the hydraulic cylinder, and an operation amount detection unit that detects an expansion / contraction operation amount of the hydraulic cylinder. The operation amount detection unit includes a first member that relatively moves along with the expansion / contraction operation of the hydraulic cylinder. A screw shaft provided integrally with one of the second members and being provided with a spiral blade on an outer peripheral portion thereof; and a screw shaft having the other of the first member and the second member. A sliding contact member provided on a member, and slidingly acting on the spiral blade with the relative movement of the first member and the second member to guide the screw shaft to rotate; The rotational speed of the over-axis and a detectable rotation sensor, in that it detects the expansion and contraction operation of the hydraulic cylinder based on the rotation speed detected by the rotation detecting sensor.

  According to the present invention, when the hydraulic cylinder expands and contracts, the first member and the second member move relatively, and the sliding contact provided on the other of the first member and the second member. The member slides on the spiral blade of the screw shaft provided on one member to rotate the screw shaft. Then, the rotation detection sensor detects the number of rotations of the screw shaft, and detects the amount of expansion / contraction operation of the hydraulic cylinder based on the number of rotations. The rotation speed of the screw shaft is a value corresponding to the relative movement amount between the first member and the second member. As the rotation detection sensor, for example, a low-cost and highly reliable electromagnetic pickup sensor that is widely used for detecting rotation of a transmission shaft in an agricultural work vehicle or the like can be used.

  As described above, since the amount of expansion / contraction operation is detected based on the number of rotations of the screw shaft obtained by the mechanical sliding action of the screw shaft and the sliding contact member, a simple structure can be used to reduce the cost. Can be achieved. In addition, even if moisture invades from the outside, it is less likely to be affected by the moisture, and the durability can be improved.

  Therefore, it is possible to detect the amount of expansion / contraction operation of the hydraulic cylinder with low cost and excellent durability even when used outdoors.

  In the present invention, an outer cylinder as the first member and an inner cylinder as the second member slidably fitted in the outer cylinder are provided, and an outer cylinder of the outer cylinder and the inner cylinder is provided. It is preferable that a cylindrical sliding member having a cylinder structure in which an end portion facing to is closed and a closed space is formed therein is provided, and the operation amount detecting means is housed inside the cylindrical sliding member. It is.

  According to this configuration, since the operation amount detection unit is housed inside the cylindrical sliding member whose periphery is covered, it is possible to prevent rainwater, muddy water, and the like from falling on the operation amount detection unit. It can be made more durable.

  In the present invention, it is preferable that the operation amount detecting means is housed inside the hydraulic cylinder, a cylinder tube in the hydraulic cylinder functions as the first member, and a piston rod in the hydraulic cylinder functions as the second member. It is.

  According to this configuration, since the hydraulic cylinder includes the cylinder tube and the piston rod that relatively move with the expansion and contraction operation, the operation amount detection unit is housed inside the hydraulic cylinder, and the cylinder tube and the piston rod are Is directly detected. Therefore, it is possible to detect the expansion / contraction operation amount by effectively using the members originally provided in the hydraulic cylinder.

It is an overall side view of a work vehicle. It is a top view which shows the wheel support structure of a working vehicle. It is a front view which shows a wheel support structure. It is a perspective view of a part of wheel support structure. It is a perspective view of a part of wheel support structure. It is a top view showing the engagement state of the operation arm. FIG. 4 is a cross-sectional front view of the vehicle height adjustment mechanism in a maximum extension state. FIG. 3 is a cross-sectional front view of the vehicle height adjusting mechanism in an intermediately extended state. It is a cross-sectional front view of the vehicle height adjustment mechanism in the shortest state. It is a figure showing a base member. It is a cross-sectional plan view of a base member. It is sectional drawing which shows the structure of a stroke sensor. It is sectional drawing which shows the structure of the stroke sensor of another embodiment.

  Hereinafter, an embodiment of a riding work vehicle according to the present invention will be described with reference to the drawings.

〔overall structure〕
FIG. 1 shows a riding work vehicle according to the present invention. This work vehicle is provided with a medicine spraying device 2 as a work device at the rear of a four-wheel running type vehicle body 1. This work vehicle performs an operation of spraying a medicine on a crop while traveling across a planting streak in a field where the crop is already planted.

  A pair of front wheels 3 are provided on the left and right sides of the front of the traveling vehicle body 1 as traveling wheels S capable of turning operation, and a pair of rear wheels 4 are provided on the left and right sides of the rear portion of the traveling vehicle body 1 as traveling wheels S. Is provided. As described above, all four wheels can be turned. For example, a two-wheel steering state in which only the two front wheels 3 are turned, and a four wheel in which the front wheel 3 and the rear wheel 4 are turned in opposite directions to travel with a small turning radius It can be switched to a steering state.

  The front wheel 3 and the rear wheel 4 are formed to be narrow so that they can run between the strips located between the crop strips. An engine 5 is mounted on a front portion of the traveling vehicle body 1, and an operation unit 6 is provided on a rear portion of the traveling vehicle body 1. At the lower part of the traveling vehicle body 1, there is provided a transmission case 7 in which a transmission (not shown) for shifting the power of the engine 5 is provided. The transmission case 7 is provided so as to extend in the front-rear direction from a lower rear portion of the engine 5 to a position corresponding to the rear wheel 4 in a side view. On the lower side of the engine 5, a front frame body 8 is provided so as to cover the outer peripheral portion. The transmission case 7 and the front-side frame body 8 are integrally connected, and a vehicle frame F that supports the entire vehicle body is configured by these components. The driving unit 6 includes a driving seat 9 on which a driver sits, and a steering handle 10 located in front of the driving seat 9 to perform a steering operation. In addition to the above, the operating unit 6 is also provided with an elevating lever 11 for elevating and lowering the working device, a shift lever 12, and the like.

  In the traveling vehicle body 1, the power of the engine 5 is transmitted to the left and right front wheels 3 and the left and right rear wheels 4 after being shifted by the transmission in the transmission case 7. Therefore, the traveling vehicle body 1 is configured as a four-wheel drive type in which four traveling wheels S are driven. As shown in FIG. 2, a lateral transmission shaft 14 is provided inside a tubular rear lateral transmission case 13 (an example of a vehicle body side case) connected to both left and right sides of the transmission case 7, and the power after shifting is transmitted laterally. The power is transmitted to the left and right rear wheels 4 via the shaft 14. The rear lateral transmission case 13 is supported by the transmission case 7, that is, the vehicle body frame F.

  As shown in FIG. 2, a tubular front side transmission case 15 (an example of a vehicle body side case) is provided at the left and right intermediate portion of the left and right front wheels 3, and the power from the transmission case 7 is transmitted to the front and rear intermediate shaft 16. The power is transmitted to the left and right front wheels 3 via a differential mechanism (not shown) provided in the lateral transmission case 15 and the lateral transmission shaft 18. The front lateral transmission case 15 is supported by the vehicle body frame F so as to freely roll around a front-rear axis X that is the same axis as the intermediate shaft 16.

  As shown in FIG. 3, a vertical transmission case 19 is connected to both left and right ends of the front horizontal transmission case 15. As shown in FIG. 7, a vertical transmission shaft 20 is provided in the vertical transmission case 19. The shaft end of the horizontal transmission shaft 18 provided in the front horizontal transmission case 15 and the upper end of the vertical transmission shaft 20 are interlocked via an upper bevel gear mechanism 21. The lower end of the vertical transmission shaft 20 and the rotation shaft 3a of the front wheel 3 are linked and connected via a lower bevel gear mechanism 22.

  The traveling wheel S is supported so as to be able to change its direction around the rotation axis Y of the vertically-oriented transmission shaft 20 with respect to the body frame F. Since the support structure of the wheel having the vertical transmission case 19 and the vertical transmission shaft 20 has the same configuration for each of the four traveling wheels S, the support structure for one of the front wheels 3 which is one of them will be described below. Will be described.

(Wheel support structure)
As shown in FIGS. 4, 5, and 7, the end of the front lateral transmission case 15 has a shape that bends in a curved shape in a front view while covering the upper bevel gear mechanism 21, and has an opening that opens downward. Is formed. An upper connector 23 integrally connected to the upper end of the vertical transmission case 19 is turned around the rotation axis Y of the vertical transmission shaft 20 around the end of the front horizontal transmission case 15 so as to cover the opening. It is movably fitted and connected. As shown in FIG. 7, a wheel support case 24 for covering the lower bevel gear mechanism 22 and supporting the rotation shaft 3 a of the front wheel 3 is connected to a lower end portion of the vertical transmission case 19.

  A stopper 25 is provided for preventing the upper connector 23 from coming off in the state of being fitted and connected. As shown in FIG. 5, the stopper 25 is formed of a strip-shaped member, one end of which is bolted to the outer peripheral portion of the upper connector 23, and the other end of which is connected to the end of the front lateral transmission case 15. Engage with the formed step portion 26 to prevent detachment.

  As shown in FIGS. 2, 3, and 4, a double-acting hydraulic cylinder 27 (hereinafter, referred to as a steering cylinder) for steering operation is positioned in front of the front lateral transmission case 15 and is parallel to the front lateral transmission case 15. , A steering cylinder). A cylinder tube 28 of the steering cylinder 27 is connected to the front lateral transmission case 15 via a bracket 29. The piston rod 30 of the steering cylinder 27 is operatively connected to one end of a tie rod 32 via a ball joint 31, and the other end of the tie rod 32 is interlocked with a knuckle arm 34 provided on the upper connector 23 via a ball joint 33. Are linked.

  When the steering cylinder 27 is operated, the vertical transmission case 19, the wheel support case 24, and the front wheel 3 are integrally integrated with each other via the knuckle arm 34 and the upper connection body 23. By turning around, the front wheel 3 is operated to change the direction. The hydraulic control valve is switched by a control device (not shown) in response to the operation of the steering handle 10 to operate the steering cylinder 27, and the steering cylinder 27 is slid to the left or right from the neutral position for straight running by hydraulic pressure.

  A rotation angle detection device 35 for detecting the rotation angle of the upper connecting body 23, that is, the rotation angle of the front wheel 3, is provided above the end of the front lateral transmission case 15. The rotation angle detection device 35 includes a potentiometer-type detection device main body 36 fixedly provided on the upper part of the front lateral transmission case 15 and a band-shaped operation arm 37. One end of the operating arm 37 is bolted to the outer peripheral portion of the upper connector 23, and the other end is engaged and linked to a rotating shaft 38 that protrudes downward from the detection device main body 36 so as to be integrally rotatable.

  As shown in FIGS. 3 and 4, the outer periphery of the detection device main body 36 is covered with a casing 39, and the casing 39 is connected to an upper portion of an end of the front lateral transmission case 15. The operation arm 37 is provided so as to extend obliquely upward from a connection point to the upper connector 23. As shown in FIG. 6, the rotating shaft 38 is machined so that its cross section becomes rectangular, and a rectangular engaging groove 40 formed at the other end of the operating arm 37 is engaged. It is interlockedly linked with the operation arm 37 in a state where it is integrally rotated.

  At an end portion of the front lateral transmission case 15, a rotation restricting portion 41 for restricting a range of a rotation operation of the upper connector 23 is formed. The configuration is such that the upper protruding portion 42 formed on the upper connector 23 is allowed to rotate within the range set by the rotation restricting portion 41.

  By the operation of the steering cylinder 27, the upper connecting body 23, that is, the vertical transmission case 19 and the front wheel 3 can rotate within the operation range regulated by the rotation regulating unit 41. The turning operation angle of the upper connector 23 is detected by the turning angle detecting device 35 and fed back to a control device (not shown), so that the steering cylinder 27 is controlled so that the turning angle corresponds to the operation of the steering handle 10. .

(Vehicle height adjustment mechanism)
Each of the vertical transmission shaft 20 and the vertical transmission case 19 has an inner / outer double structure that can expand and contract while sliding in the axial direction of the vertical transmission shaft 20. As shown in FIGS. 7, 8, and 9, the vertical transmission case 19 has an outer cylindrical member 19A and an inner cylindrical member 19B, and is configured to be able to expand and contract while sliding. The vertical transmission case 19 is provided with the outer cylinder member 19A located on the lower side and the inner cylinder member 19B located on the upper side, and the lower end of the outer cylinder member 19A is integrally connected to the wheel support case 24. The upper end of the inner cylindrical member 19 </ b> B is integrally connected to the upper connector 23.

  As shown in FIGS. 7, 8, and 9, the vertical transmission shaft 20 is slidable in the axial direction while maintaining a state of being integrally rotated by being spline-fitted inside the cylindrical shaft 20A with the cylindrical shaft 20A. And a shaft 20B. The upper end of the inner shaft 20B is connected to the upper bevel gear mechanism 21 so as to be integrally rotatable. The lower end of the cylindrical shaft 20A is connected to the lower bevel gear mechanism 22 so as to be integrally rotatable.

  A hydraulically operated type in which the vertical transmission shaft 20 and the vertical transmission case 19 can be expanded and contracted in the rotation axis Y direction of the vertical transmission shaft 20 to switch the relative height of the front wheels 3 with respect to the body frame F in a plurality of stages. The vehicle height adjustment mechanism 43 is provided. As shown in FIGS. 3, 7, 8, and 9, the vehicle height adjusting mechanism 43 includes a plurality of hydraulic cylinders 44 extending along the axial direction of the longitudinal transmission shaft 20, and a base member supporting the plurality of hydraulic cylinders 44. 45 are provided. The plurality of hydraulic cylinders 44 are arranged at different positions in the circumferential direction on the outer peripheral side of the vertical transmission case 19 and at positions facing each other with the vertical transmission case 19 interposed therebetween.

  In addition, as the plurality of hydraulic cylinders 44, two upper hydraulic cylinders 44 a that can be extended upwardly with respect to the base member 45, and can be extended downwardly with respect to the base member 45. And two lower hydraulic cylinders 44b. The two upper hydraulic cylinders 44 a are arranged at different positions in the circumferential direction on the outer peripheral side of the vertical transmission case 19 and at positions facing each other across the vertical transmission case 19. Similarly, the two lower hydraulic cylinders 44b are arranged at different positions in the circumferential direction on the outer peripheral side of the vertical transmission case 19 and at positions facing each other with the vertical transmission case 19 interposed therebetween.

  The upper hydraulic cylinder 44a and the lower hydraulic cylinder 44b are arranged at different positions in the circumferential direction. That is, as shown in FIG. 10, the lower hydraulic cylinder 44b is located in a state where it is located at a substantially intermediate portion in the circumferential direction between the two upper hydraulic cylinders 44a when viewed in the axial direction.

  The upper hydraulic cylinder 44a is provided with the piston rod 46 positioned on the upper side and the cylinder tube 47 positioned on the lower side. The lower hydraulic cylinder 44b has the piston rod 48 positioned on the lower side and the cylinder tube 49 It is provided in a state located on the upper side. The distal ends of the piston rods 46 of the two upper hydraulic cylinders 44a are integrally connected to the upper connector 23, and the distal ends of the piston rods 48 of the two lower hydraulic cylinders 44b are integrally formed with the wheel support case 24. Are linked. The cylinder tubes 47 of the two upper hydraulic cylinders 44a and the cylinder tubes 49 of the two lower hydraulic cylinders 44b are integrally connected to the base member 45. Therefore, the upper hydraulic cylinder 44a is located above the base member 45, and the lower hydraulic cylinder 44b is located below the base member 45.

  The upper end of the vertical transmission case 19 and the upper ends of the two upper hydraulic cylinders 44a are integrally connected to the upper connector 23, and the lower ends of the two lower hydraulic cylinders 44b are integrally connected to the wheel support case 24. Have been. The cylinder tubes 47 of the two upper hydraulic cylinders 44a and the cylinder tubes 49 of the two lower hydraulic cylinders 44b are integrally connected to the base member 45. Therefore, the upper connector 23 and the wheel support case 24 are integrally connected via the four hydraulic cylinders 44 and the base member 45, and when the steering cylinder 27 operates, the members rotate integrally. Then, the front wheel 3 is turned.

  When the four hydraulic cylinders 44 are extended, as shown in FIG. 7, in the state where the vertical transmission case 19 is extended most, the outer peripheral side of the overlapping portion 50 where the outer cylindrical member 19A and the inner cylindrical member 19B overlap is the base member. 45 supported. In this way, even when the vertical transmission case 19 is elongated and the vertical width of the overlapping portion 50 is narrow, the outer peripheral side is supported by the base member 45, thereby preventing a reduction in support strength.

  As shown in FIGS. 7, 8, and 9, a supporting boss 51 that rotatably supports the inside of the vertical transmission case 19 is provided at an end of the horizontal transmission case 15 to which the upper connector 23 is rotatably connected. Are provided radially inward of the vertical transmission case 19 and extend downward along the rotation axis Y direction. That is, at the end of the horizontal transmission case 15, the support boss portion 51 that rotatably supports the inner peripheral side of the upper connector 23 via the bearing 52 is integrally formed along the axis of the vertical transmission shaft 20. It is formed to extend in a state of extending downward. The support boss 51 rotatably supports the vertical transmission shaft 20 located on the inner peripheral side via a bearing 53.

  The support boss portion 51 is provided so as to extend downward to a lower side than an intermediate portion in the vertical direction of the outer cylindrical member 19A. As described above, the vertical transmission case 19 is supported from the inner peripheral side by the support boss portion 51 which is long in the vertical direction, so that a decrease in the support strength of the vertical transmission case 19 is prevented.

  A communication oil passage 56 that connects the oil chamber 54 of the upper hydraulic cylinder 44a and the oil chamber 55 of the lower hydraulic cylinder 44b is formed in the vehicle height adjusting mechanism 43 so that the inside of the base member 45 is inserted. Then, after the hydraulic oil is supplied to the oil chamber 54 of the upper hydraulic cylinder 44a while the communication oil path 56 is switched to the closed state to extend the upper hydraulic cylinder 44a, the communication oil path 56 is opened. The operation mode is sequentially switched to supply the operating oil to the oil chamber 55 of the lower hydraulic cylinder 44b, and the operation of the oil chamber 54 of the upper hydraulic cylinder 44a and the lower hydraulic cylinder 44b in a state where the communication oil passage 56 is switched to the open state. It is configured to be switchable between a simultaneous operation mode in which hydraulic oil is simultaneously supplied to the oil chamber 55.

  In addition, as shown in FIGS. 7, 8, and 9, an internal oil passage 57 extending along the axial direction inside the shaft of the piston rod 46 of the upper hydraulic cylinder 44a integrally connected to the upper connector 23. Is formed. A hydraulic oil supply port 58 is formed in the upper connector 23, and the hydraulic oil supply port 58 is connected to an internal oil passage 57. Although not shown, hydraulic oil is supplied to the hydraulic oil supply port 58 from a hydraulic pump provided in the traveling vehicle body 1 via a hydraulic control valve. As described above, since the internal oil passage 57 is formed inside the shaft of the piston rod 46, hydraulic oil can be supplied into the oil chamber by using the internal oil passage 57, and special oil is supplied from the hydraulic oil supply port 58. There is no need to provide a simple external pipe or the like, and the hydraulic pipe can be simplified.

  As shown in FIG. 11, an oil chamber 54 inside the cylinder tube 47 of the upper hydraulic cylinder 44a communicates with an oil chamber 55 inside the cylinder tube 49 of the lower hydraulic cylinder 44b at the upper and lower intermediate positions of the base member 45. The communication oil passage 56 is formed integrally with the base member 45. An electromagnetically operated on-off valve 59 is provided at a middle portion of the communication oil passage 56.

  As shown in FIG. 9, from the shortest state in which all four hydraulic cylinders 44 are retracted, the on-off valve 59 is switched to the closed state to shut off the communication oil passage 56 and operate on the two upper hydraulic cylinders 44a. Hydraulic oil is supplied from the oil supply port 58. Then, only the two upper hydraulic cylinders 44a are switched to the extended state, and the two lower hydraulic cylinders 44b enter the intermediate extended state in which the retracted state is maintained (see FIG. 8).

  Next, when the opening / closing valve 59 is opened to further supply the operating oil from the operating oil supply port 58, the cylinder of the lower hydraulic cylinder 44 b passes from the oil chamber 54 of the cylinder tube 47 of the upper hydraulic cylinder 44 a through the communication oil passage 56. The working oil is supplied to the oil chamber 55 of the tube 49. Then, the two upper hydraulic cylinders 44a and the two lower hydraulic cylinders 44b are each in the maximum extended state where they are switched to the extended state (see FIG. 7). The operation mode in which the state is switched from the shortest state to the maximum extension state through the intermediate extension state is a sequential operation mode. Therefore, in the sequential operation mode, the ground height (vehicle height) of the traveling vehicle body 1 can be switched between three stages of a low position (shortest state), an intermediate position (intermediate extended state), and a high position (maximum extended state).

  As shown in FIG. 9, from the shortest state in which all four hydraulic cylinders 44 are retracted, the on-off valve 59 is switched to the open state to open the communication oil passage 56 and operate on the two upper hydraulic cylinders 44a. When the operating oil is supplied from the oil supply port 58, the operating oil is supplied through the internal oil passage 57 and the communication oil passage 56, and the two upper hydraulic cylinders 44a and the two lower hydraulic cylinders 44b are simultaneously extended. It switches to the maximum extension state (see FIG. 7). Such an operation mode in which the shortest state is switched to the maximum extension state is a simultaneous operation mode. Therefore, in the simultaneous operation mode, the ground height (vehicle height) of the traveling vehicle body 1 can be switched between a low position (shortest state) and a high position (maximum extended state).

  Although not shown, the switching between the sequential operation mode and the simultaneous operation mode is performed by the mode switching operation tool provided in the driving unit 6, and the vehicle height changing operation is performed by the vehicle height switching operation tool provided in the driving unit 6. The control device (not shown) controls the operation so that the hydraulic control valve and the opening / closing valve 59 are switched to corresponding states according to the operation of the mode switching operation tool and the vehicle height switching operation tool. . The configuration is not limited to the configuration in which the sequential operation mode and the simultaneous operation mode are respectively provided, but may be a configuration in which one of the modes is provided.

  As shown in FIG. 3, a stroke sensor serving as an operation amount detecting means is located on the inner side of the vertical transmission case 19 in the vehicle width direction and extends vertically along the extending direction of the vertical transmission case 19. 60 are provided. The stroke sensor 60 is provided over the upper connector 23 and the support bracket 61 provided below the wheel support case 24.

  As shown in FIG. 12, an outer cylinder 62 as a first member that relatively moves with the expansion and contraction operation of the four hydraulic cylinders 44 and an inner cylinder as a second member slidably fitted in the outer cylinder 62. 63, and a cylindrical sliding member 64 having a cylinder structure in which the outer ends of the outer cylinder 62 and the inner cylinder 63 facing outside are closed and a closed space is formed therein. In the cylindrical sliding member 64, the upper end of the outer cylinder 62 is connected to the upper connector 23, and the lower end of the inner cylinder 63 is connected to the support bracket 61.

  As shown in FIG. 12, a stroke sensor 60 is housed inside a tubular sliding member 64. The stroke sensor 60 is provided in the inner cylinder 63 and the screw shaft 66 provided so as to move integrally with the outer cylinder 62 and in a state where the spiral blade 65 is integrally fixed to the outer peripheral portion. A sliding contact member 67 that guides the screw shaft 66 to rotate by slidingly contacting the spiral blade 65 with the relative movement between the inner cylinder 63 and the outer cylinder 62, and a rotation capable of detecting the rotation speed of the screw shaft 66. And an electromagnetic pickup sensor 68 as a detection sensor. The spiral blade 65 may be formed integrally with the outer cylinder 65, or may be formed separately from the outer cylinder 65 and then attached in a fixed state.

  The screw shaft 66 is supported by a support portion 69 provided at the upper end of the outer cylinder 62 so as to move integrally along the axial direction and to be rotatable in the circumferential direction. The screw shaft 66 extends along the inside of the inner cylinder 63. At the upper end of the inner cylinder 63, there is provided a sliding member 67 which is externally inserted into the screw shaft 66 and which slides on the spiral blade 65. On the screw shaft 66, a detection gear 70 is provided at a position extending above the sliding contact member 67. The outer cylinder 62 is provided with a well-known electromagnetic pickup sensor 68 at a position corresponding to the outer peripheral portion of the detection gear 70. The pickup sensor 68 is widely used, for example, in agricultural machines and other devices, and can accurately detect the number of rotations.

  When the outer cylinder 62 and the inner cylinder 63 move relative to each other in the axial direction in accordance with the expansion and contraction of the four hydraulic cylinders 44, the spiral blade 65 of the screw shaft 66 receives the sliding action of the sliding member 67, and the amount of movement is increased. The screw shaft 66 rotates by a rotation amount corresponding to. The pickup sensor 68 can detect the number of rotations of the screw shaft 66 based on the waveform of the current generated when the teeth of the detection gear 70 pass with the rotation of the screw shaft 66. By counting the number of rotations of the screw shaft 66 from the start of rotation to the stop, the amount of movement of the screw shaft 66 in the axial direction (the amount of expansion / contraction operation accompanying the expansion / contraction operation of the four hydraulic cylinders 44) is determined. You can ask.

[Another embodiment]
(1) In the above embodiment, a cylindrical sliding member 64 having a cylinder structure is provided separately from the four hydraulic cylinders 44, and the operation amount detecting means (stroke) is stored in the cylindrical sliding member 64. Although the sensor 60) is provided, the operation amount detecting means may be housed inside the hydraulic cylinder 44 instead of this structure.

  Although not shown, the piston rod is formed in a cylindrical shape like the inner cylinder 63 of the above embodiment, and a screw shaft 66 is provided inside the cylindrical piston rod. On the other hand, the cylinder tube is provided with a support portion 69 similar to that of the above-described embodiment, and supports the screw shaft 66 so as to be able to move integrally and to allow rotation. Then, a pickup sensor 68 is provided in the cylinder tube. Therefore, the cylinder tube in the hydraulic cylinder 44 functions as a first member, and the piston rod in the hydraulic cylinder 44 functions as a second member. Incidentally, in the case where the upper hydraulic cylinder 44a and the lower hydraulic cylinder 44b are provided as in the above-described embodiment, the stroke sensors are respectively housed in the respective hydraulic cylinders, and the expansion / contraction operation amount of the upper hydraulic cylinder 44a and the lower hydraulic pressure are determined. The value obtained by adding the expansion / contraction operation amount of the cylinder 44b is the entire expansion / contraction operation amount.

(2) In the above embodiment, the configuration is such that the electromagnetic pickup sensor 68 is provided as the rotation detection sensor. However, instead of this configuration, another type of rotation sensor such as a rotary encoder may be used.

(3) In the above embodiment, the medicine spraying device 2 is provided as the working device. However, the working device may be provided with a fertilizer application device or another type of working device.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a riding-type work vehicle in which a riding-type traveling body has a plurality of traveling wheels.

DESCRIPTION OF SYMBOLS 1 Running vehicle body 44 Hydraulic cylinder 46,48 Piston rod 47,49 Cylinder tube 60 Operation amount detecting means (stroke sensor)
62 First member (outer cylinder)
63 Second member (inner cylinder)
64 cylindrical sliding member 65 spiral blade 66 screw shaft 67 sliding contact member 68 rotation detection sensor (pickup sensor)
F Body frame S Running wheels

Claims (3)

A traveling body, a body frame, traveling wheels supported so as to be capable of changing a relative height with respect to the body frame, a hydraulic cylinder capable of switching a relative height of the traveling wheels with respect to the body frame, and expansion and contraction of the hydraulic cylinder Operation amount detection means for detecting the operation amount,
The operation amount detection means includes:
A screw shaft that is provided in a state of moving integrally with one of the first member and the second member that relatively move with the expansion and contraction operation of the hydraulic cylinder, and that has a spiral blade on an outer peripheral portion. When,
The screw member is provided on the other of the first member and the second member, and slides on the spiral blade as the first member and the second member move relative to each other to move the screw shaft. A sliding contact member for guiding rotation,
Having a rotation detection sensor capable of detecting the number of rotations of the screw shaft,
A riding work vehicle that detects an amount of expansion / contraction operation of the hydraulic cylinder based on a rotation speed detected by the rotation detection sensor. An outer cylinder as the first member, and an inner cylinder as the second member slidably fitted in the outer cylinder, and an end facing the outer cylinder and the inner cylinder facing outward. Closed, provided with a cylindrical sliding member of a cylinder structure having a closed space formed therein,
The riding type work vehicle according to claim 1, wherein the operation amount detection means is housed inside the cylindrical sliding member. The operation amount detection means is housed inside the hydraulic cylinder,
The riding work vehicle according to claim 1, wherein a cylinder tube of the hydraulic cylinder functions as the first member, and a piston rod of the hydraulic cylinder functions as the second member.

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