JP2007333036A - Gear shift device of work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear shift device which is advantageous in footprint and structure as well as being capable of preventing a static hydraulic stepless speed change device from being subjected to a gear shift movement while preventing a gear shift lever from returning swiftly due to a return energizing spring. <P>SOLUTION: The gear shift device is equipped with: a gear shift lever 24 which performs a gear shift of the static hydraulic stepless speed change device for driving a traveling device and can be manually freely operated; and a positioning mechanism 70 which positions the gear shift lever 24 at a neutral state. The positioning mechanism 70 is equipped with: an energizing mechanism 74 which returns and energizes the gear shift lever 24 at the neutral state by means of a spring 73; and a rotary dumper 81 which is interlinked with a rotary spindle 80 of the gear shift lever 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a shift operation tool that can be manually operated to shift a hydrostatic continuously variable transmission that drives a traveling device, and a shift operation of a work vehicle including a positioning mechanism that positions the shift operation tool in a neutral state. Relates to the device.

The above-described shift operation device positions the shift operation tool in a neutral state by a positioning mechanism so that the hydrostatic continuously variable transmission can be easily held in a neutral state.
Conventionally, as this type of transmission, there has been one disclosed in Patent Document 1, for example.
The device disclosed in Patent Document 1 includes a shift pedal (corresponding to a shift operation tool) and a neutral device (corresponding to a positioning mechanism). The neutral device includes an intermediate link interlocked with the speed change pedal via a first interlocking rod, a pressing member, and a roller provided to the pressing member by swinging and energizing the pressing member, so that the V-shaped side surface of the intermediate link is provided. And an urging spring for urging and applying to.
Moreover, what is shown by patent document 1 is provided with the damper connected with the intermediate link. This damper provides resistance to return swinging to the neutral position of the intermediate link.

JP 2001-32926 (paragraphs [0028] and [0029], FIGS. 2 and 3)

If the positioning mechanism is provided with a spring that urges the shifting operation tool to return to the neutral state, when the operation of the shifting operation tool is released, the shifting operation tool operates vigorously toward the neutral state in order to restore the elasticity of the spring. Sometimes.
According to the above-described conventional technical matters, it is possible to obtain a speed change operation device that can prevent the above-described operation trouble of the speed change operation tool with a damper. However, since the damper has a telescopic structure, the speed change operation device tends to be large due to the space and structure required for installing and supporting the damper. Further, the structure of the speed change operation device tends to be complicated.

  While the object of the present invention is to provide a positioning mechanism with a spring, it is possible to prevent the above-described operation troubles of the speed change operation tool and to avoid the problems in the installation space and the structure. An object of the present invention is to provide a shift operation device for a work vehicle.

A first aspect of the present invention is a work vehicle equipped with a manually operated shift operation tool that shifts a hydrostatic continuously variable transmission that drives a traveling device, and a positioning mechanism that positions the shift operation tool in a neutral state. In the speed change operation device,
The positioning mechanism includes an urging mechanism that urges the shifting operation tool to return to a neutral state by a spring, and a rotary damper that is linked to a rotating body of the urging mechanism or a rotation support shaft of the shifting operation tool. Configured.

  According to the configuration of the first aspect of the present invention, the positioning mechanism biases the shift operation tool back to the neutral state by the spring, thereby positioning the shift operation tool in the neutral state. However, resistance can be applied to the speed change operation tool by the rotary damper so that the speed change operation tool does not operate vigorously toward the neutral state due to the spring. Since the rotary damper has a structure that provides resistance to rotation and the internal rotor rotates, the space required for installing and supporting the damper may be smaller than that of the damper having a telescopic structure.

  As a result, a spring for returning and biasing the speed change operation tool to the neutral state is employed, but the speed change operation tool operates quietly toward the neutral state, and it is difficult for a sudden speed change to occur and the speed change operation is easy. The speed change operation device can be obtained with a compact and simple structure in which the rotary damper is interlocked with the rotating body of the urging mechanism or the rotation support shaft of the speed change operation tool.

  The second aspect of the present invention is based on a potentiometer that detects an operation position of the shift operation tool, a shift actuator that operates the hydrostatic continuously variable transmission, and detection information obtained by the potentiometer. And a control means for operating the speed change actuator so as to be in a speed change state corresponding to the operating position of the speed change operating tool.

  According to the configuration of the second aspect of the present invention, it is possible to easily obtain the structure of a speed change operation device that can be easily operated for speed change but is less likely to be erroneously operated.

  In other words, if the potentiometer is operated by the speed change operation tool, the speed change actuator is operated to change the speed of the hydrostatic continuously variable transmission, and the required speed change operation force can be reduced. Nevertheless, the rotary damper prevents the shift operation tool from operating vigorously toward the neutral state due to the spring and the shift operation tool from being excessively operated, and operates the shift operation tool for a desired stroke. It can be operated in an easy-to-control state.

  In the third aspect of the invention, the rotary damper is linked to one end side of the rotation support shaft of the speed change operation tool, and the potentiometer is linked to the other end side of the rotation support shaft.

  According to the configuration of the third aspect of the invention, the interlocking mechanism for interlocking the rotary damper with the rotating support shaft and the interlocking mechanism for interlocking the potentiometer with the rotating support shaft are each configured as a dedicated interlocking mechanism to rotate the rotary damper and the potentiometer. Can be linked to the spindle.

  Thereby, the interlocking mechanism of the rotary damper and the interlocking mechanism of the potentiometer can be obtained in a dedicated compact and simple structure, and from this aspect, the speed change operation device can be obtained in a compact and simple structure.

  According to the fourth aspect of the present invention, a rotor operation body of the rotary damper is positioned concentrically with the rotation support shaft of the speed change operation tool and is interlocked with the rotation support shaft. It is being fixed to the support body which supports rotatably.

  According to the configuration of the fourth aspect of the invention, the rotary damper can be supported by using the support body of the speed change operation tool for the damper. This eliminates the need for a dedicated support member for the rotary damper, and the shift operating device can be obtained in a compact and simple structure from this aspect.

Embodiments of the present invention will be described below with reference to the drawings.
[First Example]
In the embodiments of the present invention, a case where the present invention is applied to a tractor will be described as an example. FIG. 1 is an overall side view of the tractor. As shown in this figure, the tractor includes a vehicle body frame 4 having a clutch housing 4A connected to the rear portion of the engine 1, and a pair of left and right provided at the front portion of the vehicle body frame 4 so as to be steerable and drivable. Front wheels 3, 3, a pair of left and right rear wheels 5, 5 movably provided at the rear of the vehicle body frame 4, and a driver seat 7 and a driver seat 7 positioned above the rear end of the vehicle body frame 4 A driving portion 8 having a steering wheel 6 positioned in the front, a pair of left and right lift arms 18 and 18 provided at the rear end portion of the vehicle body frame 4 so as to be vertically driven and swingable, and a rear end portion of the vehicle body frame 4 And a power take-out shaft 15 protruding rearward from the vehicle body.

  The vehicle body frame 4 includes the engine 1 and the clutch housing 4A, a front frame 2 connected to a lower portion of the engine 1, a transmission case 4B connected to a rear portion of the clutch housing 4A, and the transmission. A rear transmission case 4C connected to the rear end side of the case 4B is provided. The front frame 2 supports the front wheels 3, 3 on the left and right. The rear mission case 4C supports the pair of left and right rear wheels 5 and 5, and includes the pair of left and right lift arms 18 and 18 and the power take-out shaft 15.

  The tractor connects a rotary tiller (not shown) to the rear of the vehicle body so as to be lifted and lowered by the pair of left and right lift arms 18 and 18, and the driving force of the engine 1 is rotary tilled from the power take-out shaft 15. Various riding devices are constructed by connecting various working devices to the rear part of the vehicle body so that they can be lifted and driven, such as a riding type tiller.

FIG. 2 is a diagram of a traveling transmission device included in the tractor. As shown in this figure, the driving transmission is provided in the main clutch 9 provided in the clutch housing 4A, the main transmission 10 provided in the transmission case 4B, and the rear transmission case 4C. A sub-transmission 11 and a rear-wheel differential mechanism 13 are provided, and a front-wheel differential mechanism 12 linked to a front-wheel output gear 11a of the sub-transmission 11 via a clutch gear 11b and a front-wheel transmission shaft 11c is provided.
The main clutch 9 transmits the driving force from the engine 1 to the input shaft 16 a of the main transmission 10. The main transmission 10 shifts the driving force input by the input shaft 16a, and outputs the driving force after the shift from the output shaft 17a to the auxiliary transmission 11. The auxiliary transmission 11 is shifted between a high speed state and a low speed state when the shift gear 11d is operated to shift, and the driving force from the main transmission 10 is shifted in two stages of high speed and low speed to change the rear wheel differential mechanism 13. And output to the front wheel differential mechanism 12.

  FIG. 3 is a vertical side view of a portion where the main clutch 9 and the main transmission 10 of the traveling transmission are located. FIG. 4 is a cross-sectional plan view of the main transmission 10. As shown in these drawings, the main transmission 10 is driven by an axial plunger type, variable displacement type hydraulic pump 16 in which the input shaft 16 a serves as a pump shaft, and pressure oil from the hydraulic pump 16. An axial plunger type hydraulic motor 17 is provided. That is, the main transmission 10 is a hydrostatic continuously variable transmission. As a result, the main transmission 10 (hereinafter, abbreviated as the continuously variable transmission 10) is operated to change the swash plate angle of the hydraulic pump 16, so that the driving force from the engine 1 is driven forward and backward. And the forward drive force and the reverse drive force are steplessly shifted and output from the output shaft 17a, which is the motor shaft of the hydraulic motor 17, via the auxiliary transmission 11 and the rear wheel differential mechanism 13. The left and right rear wheels 5 and 5 are driven, and the left and right front wheels 1 and 1 are driven via the auxiliary transmission 11 and the front wheel differential mechanism 12.

  As shown in FIG. 2, the work transmission device provided in the tractor is configured such that the driving force of the input shaft 16 a (pump shaft of the hydraulic pump 16) of the main transmission 10 is applied to the power take-out shaft 15 via the work clutch 14. To communicate.

  FIG. 5 is a block diagram of the traveling operation device provided in the tractor. As shown in this figure, the travel operation device operates a hydraulic transmission cylinder 26 that performs a speed change operation on the continuously variable transmission 10 (hereinafter abbreviated as a transmission cylinder 26), and an accelerator device 40 of the engine 1. An electric actuator 41 (hereinafter referred to as an accelerator actuator 41) and a control means 21 linked to the accelerator actuator 41 and linked to a servo control mechanism 20 that controls the shift cylinder 26 are provided. Further, the traveling operation device detects the operation position of the shift pedal 24 and the accelerator lever 25 provided in the driving unit 8 and the shift pedal 24 and outputs the detected information to the control means 21 as a rotary type sensor. A potentiometer 27 (hereinafter referred to as a pedal sensor 27) and a rotary potentiometer 28 (hereinafter referred to as an accelerator lever sensor) as a sensor for detecting the operation position of the accelerator lever 25 and outputting the detected information to the control means 21. 28)). Further, the traveling operation device switches the interlocking mechanism 50 between the on state and the off state by the interlocking mechanism 50 that interlocks the shift pedal 24 and the operation unit 40 a of the accelerator device 40 and the interlocking on / off lever 61 provided in the driving unit 8. An operation mechanism 60 for switching operation and a detection switch 29 (hereinafter referred to as an on / off sensor 29) as a sensor for detecting the operation position of the interlocking on / off lever 61 and outputting the detection information to the control means 21 are provided. ing.

  As shown in FIG. 4, the speed change cylinder 26 is installed inside the transmission case 4B, and the swash plate 16b of the hydraulic pump 16 is operated to rotate via the interlocking pin 26a so that the cylinder of the swash plate 16b. By changing the angle with respect to the block 16c, the continuously variable transmission 10 is shifted. As shown in FIG. 5, the servo control mechanism 20 includes a forward proportional control valve 31 and a reverse proportional control valve 32, and the forward proportional control valve 31 and the reverse proportional control valve 32 are switched by a command from the control means 21. Then, the speed change cylinder 26 is operated so that the continuously variable transmission 10 is in a speed change state corresponding to the operation position of the speed change pedal 24. As shown in FIG. 4, the servo control mechanism 20 is mounted on the transmission case 4B.

  The control means 21 is configured using a microcomputer, and a swash plate sensor 34 that detects a shift state of the continuously variable transmission 10 based on information detected by the pedal sensor 27 and the angle of the swash plate 16b. The continuously variable transmission 10 is operated via the servo control mechanism 20 so that the continuously variable transmission 10 enters a shift state corresponding to the operation position of the shift pedal 24 based on the detection information obtained by the above.

  Based on the information detected by the on / off sensor 29, the control means 21 determines whether the interlock mechanism 50 is in the on state or the off state, and if it is determined that the interlock mechanism 50 is in the off state, Based on the detection information by the lever sensor 28 and the detection information by the accelerator sensor 35 that detects the operation state of the accelerator device 40, the accelerator device 40 causes the engine 1 to display a rotational speed corresponding to the operation position of the accelerator lever 25. The accelerator actuator 41 is operated so as to be in the operation state. On the other hand, when it is determined that the interlocking mechanism 50 is in the on state, the control unit 21 stops the operation of the accelerator actuator 41 based on the detection information by the accelerator lever sensor 28 and the accelerator sensor 35 and the shift pedal 24 is operated. The accelerator actuator 41 is switched to a state in which the operation by the external force can be performed so that the operation of the accelerator device 40 can be performed.

  When the tractor is driven, when the shift pedal 24 is depressed from the neutral state to the front side of the vehicle body by the front operation portion 24a (see FIGS. 6 and 8), the control means 21 operates the shift cylinder 26 to the forward side to continuously change the speed. The device 10 is operated to shift forward and the tractor travels forward. When the shift pedal 24 is stepped on from the neutral state to the rear side of the vehicle body by the rear operation portion 24b (see FIGS. 6 and 8), the control means 21 operates the shift cylinder 26 to the reverse side and the continuously variable transmission 10 is moved to the reverse side. As a result, the tractor travels backward. In both forward travel and reverse travel, as the depressing stroke of the speed change pedal 24 is increased, the control means 21 operates the speed change cylinder 26 to the higher speed side to change the continuously variable transmission 10 to the higher speed side. Tractor speed increases.

  When the tractor travels in this manner, for example, when traveling on the road, the interlocking on / off lever 61 is switched to the on position ON. Then, the interlock mechanism 50 is turned on by the operation of the operation mechanism 60, and the shift pedal 24 and the accelerator device 40 are interlocked. As a result, when the shift pedal 24 is depressed, the accelerator device 40 is actuated to increase the speed in association with this, and the rotational speed of the engine 1 is increased. As the stepping stroke of the speed change pedal 24 is increased and the change in the continuously variable transmission 10 toward the high speed side is increased, the accelerator device 40 is operated at a higher speed side and the engine speed is further increased. As a result, even if the vehicle travels at a high speed, the engine speed increases and the engine stop is less likely to occur. On the other hand, when the operation with respect to the shift pedal 24 is released and the shift pedal 24 is operated to the low speed side by the return operation by the positioning mechanism 70 provided in the shift pedal 24, the accelerator device 40 is operated to the deceleration side in conjunction with this. . As a result, if the vehicle travels at a low speed, the rotational speed of the engine 1 decreases and fuel consumption decreases.

  On the other hand, when working, the interlocking on / off lever 61 is switched to the cutting position OFF. Then, the interlock mechanism 50 is turned off by the operation of the operation mechanism 60, and the interlock between the shift pedal 24 and the accelerator device 40 is disconnected. Accordingly, the accelerator device 40 maintains the speed state set by the accelerator lever 25 regardless of whether the shift pedal 24 is depressed or returned to the low speed side. For this reason, even if the traveling speed is changed, the rotational speed of the engine 1 does not change, and the connected working devices maintain a predetermined driving rotational speed.

  FIG. 6 is a side view of the positioning mechanism 70 provided in the speed change pedal 24. FIG. 9 is a perspective view of a part of the positioning mechanism 70. As shown in these drawings, the positioning mechanism 70 includes a coil-shaped spring 73 supported at one end by a spring holder 72 provided in a base body 71 fixed to the lower surface side of the floor plate 8a of the operation unit 8. A mechanism 74 and a rotary damper 81 linked to one end side of the rotation support shaft 80 of the shift pedal 24 are provided.

  The urging mechanism 74 includes the spring 73, a rotating member 75 that is rotatably supported by a connecting cylinder portion 75a on a support shaft 71a of the base body 71, and an end portion of an arm portion 75b of the rotating member 75. Is connected to a connecting piece 24a located at the rear end of the speed change pedal 24, and a positioning rocking body 78 supported on a support shaft 71b of the base body 71 so as to be swingable by a connecting cylinder part 78a. And a cam mechanism 79 provided between the other swing link portion 78b of the positioning swing body 78 and the cam plate portion 75c of the rotating member 75. The spring 73 is connected to one of the pair of swing link portions 78b and 78c of the positioning swing body 78.

  As shown in FIGS. 6 and 9, the cam mechanism 79 includes a V-shaped inclined cam surface 79 a provided on the cam plate portion 75 c of the rotating member 75 and the swing link portion 78 b of the positioning swing body 78. The rotary cam follower 79b is provided with a roller rotatably supported. The spring 73 swings and biases the swing link portion 78c, thereby biasing and biasing the cam follower 79b against the inclined cam surface 79a.

  As shown in FIG. 8, the rotary damper 81 includes a main body case 81a, a rotor 81b rotatably accommodated in the main body case 81a, a damper oil accommodated in the main body case 81a, And a rotor operation body 81c interlocked with the rotor 81b. The main body case 81a supports the pair of vertical pieces 82a of the support body 82 that supports the transmission pedal 24 in a swingable manner by supporting the rotation support shaft 80 of the transmission pedal 24 with a pair of vertical pieces 82a, 82a. , 82a is fixed to one outer surface. The rotor operation body 81c is connected to the rotary support shaft 80 so as to be integrally rotatable in a state of being arranged concentrically with the rotary support shaft 80.

  That is, regardless of whether the shift pedal 24 is depressed from the neutral state to either the forward side or the reverse side, the rotating member 75 rotates around the axis of the support shaft 71 in conjunction with the swing of the shift pedal 24. Then, due to the action of the cam mechanism 79, the positioning oscillating body 78 rotates the rotating member 75 so as to return to the initial position. As a result, the positioning mechanism 70 positions the shift pedal 24 in a neutral state by the elastic restoring force of the spring 73, and sets the shift pedal 24 in a neutral state even when the shift pedal 24 is depressed to either the forward side or the reverse side. Perform return operation. Further, the positioning mechanism 70 applies rotational resistance to the shift pedal 24 by the rotary damper 81 so that the shift pedal 24 that is returned by the spring 73 does not operate vigorously in the neutral state.

  As shown in FIGS. 7, 9, and 11, the interlocking mechanism 50 that interlocks the shift pedal 24 and the accelerator device 40 is connected to the positioning mechanism 70 and the support shaft 71 b that supports the positioning rocking body 78. Accelerator interlocking member 51 that is swingably supported by 51 a, one of the pair of swing link portions 51 b and 51 c provided in this accelerator interlocking member 51, and one swing link portion 78 c of the positioning swing body 78. An engagement mechanism 52 provided between the operation link 53, the operation cable 53 linking the other swing link 51 c of the accelerator interlocking member 51 with the operation unit 40 a of the accelerator device 40, and the one of the accelerator interlocking members 51. And a return spring 54 connected to the swing link portion 51c.

  The accelerator interlocking member 51 is slidably supported on the support shaft 71b so as to approach and separate from the positioning rocking body 78. The engaging mechanism 52 is configured to be inserted into the pin hole 52a provided in the swing link portion 78c of the positioning swing body 78, and to enter the pin hole 52a, and is fixed to the swing link portion 51b of the accelerator interlocking member 51. The interlocking pin 52b is used.

  11 is a plan view of the engagement mechanism 52 in a disengaged state, and FIG. 12 is a plan view of the engagement mechanism 52 in an engaged state. As shown in these drawings, that is, when the accelerator interlocking member 51 is slid along the support shaft 71b so as to approach the positioning rocking body 78, the interlocking pin 52b enters the pin hole 52a. Then, the engaging mechanism 52 is in an engaged state in which the positioning rocking body 78 and the accelerator interlocking member 51 are engaged so as to rock integrally. On the other hand, when the accelerator interlocking member 51 is slid along the support shaft 71b so as to be separated from the positioning rocking body 78, the interlocking pin 52b is detached from the pin hole 52a. Then, the engagement mechanism 52 enters a disengaged state in which the positioning rocking body 78 and the accelerator interlocking member 51 are disengaged so as to relatively rock.

  As shown in FIGS. 7, 9, and 11, the operation mechanism 60 for switching the interlocking mechanism 50 between the on state and the off state includes the interlocking on / off lever 61, the positioning swing body 78, and the accelerator interlocking member. 51, a spring 62 positioned in a state of being externally fitted to a support shaft 71b, an operation arm 64 supported by the base body 71 through a support shaft 63 so as to be swingable, and a cable connection of the operation arm 64 An operation cable 65 having one end of the inner cable 65a coupled to the portion 64a is provided.

  The other end side of the inner cable 65 a of the operation cable 65 is connected to the interlocking turning lever 61. The spring 62 slidably biases the accelerator interlocking member 51 toward the side away from the positioning swinging body 78 so that the interlocking pin 52b of the engagement mechanism 52 is pulled out from the pin hole 52a. The interlocking on / off lever 61 is supported by a support 67 through a lever support shaft 66, and a guide groove 68a of a lever guide 68 provided in the support 67 around the axis of the lever support shaft 66 (see FIG. 10). Swing operation can be performed along A rotatable roller 64 b is provided at the tip of the operation arm 64. The operating arm 64 is operated to swing around the axis of the support shaft 63, thereby bringing the roller 64 b into contact with the swing link portion 51 c of the accelerator interlocking member 51 and positioning the accelerator interlocking member 51 with the positioning swinging body 78. The spring 62 is pressed against the spring 62 or the swing link 51c is not pressed by the roller 64b, and the accelerator interlocking member 51 is moved away from the positioning swing body 78 by the spring 62. .

  That is, when the interlocking on / off lever 61 is swung along the guide groove 68a, the operation mechanism 60 swings the operation arm 64 by the pulling force of the operation cable 65, and the operation arm 64 causes the roller 64b to swing. By moving the accelerator interlocking member 51 closer to the positioning rocking body 78 via the engagement mechanism 52, the engaging mechanism 52 is switched to the engaged state and the interlocking mechanism 50 is switched to the on state, or the spring 62 is operated. By moving the accelerator interlocking member 51 away from the positioning rocking body 78 by the urging force, the engaging mechanism 52 is switched to the disengaged state and the interlocking mechanism 50 is switched to the disengaged state.

  That is, when the shift pedal 24 and the accelerator device 60 are interlocked, the interlock on / off lever 61 is swung along the guide groove 68a to switch to the ON position ON located at one end side of the guide groove 68a. Then, the operating mechanism 60 operates the accelerator interlocking member 51 to approach the positioning rocking body 78 by the operating arm 64, and the engaging mechanism 52 is switched to the engaged state. As a result, the interlocking mechanism 50 is turned on, and the operating force of the shift pedal 24 is controlled by the accelerator device 40 via the interlocking rod 76, the rotating member 75, the positioning rocking body 78, the interlocking pin 52b, the accelerator interlocking member 51, and the operation cable 53. To the operation unit 40a.

  In this case, the swinging direction of the shift pedal 24 is different and the rotation direction of the rotating member 75 is different when the shift pedal 24 is depressed forward and when it is depressed backward. However, regardless of whether the shift pedal 24 is depressed forward from the neutral state or when it is depressed backward, the positioning rocking body 78 is moved from the initial position to the same rocking direction due to the action of the inclined cam surface 79a. And the operation cable 53 is pulled. As a result, regardless of whether the shift pedal 24 is depressed forward or backward, the operation unit 40a of the accelerator device 40 is swung to the high speed side in conjunction with the depression of the shift pedal 24. And the accelerator device 40 work together. Further, in this case, the interlocking on / off lever 61 is maintained inside the notch 68b by the spring 69 by operating the interlocking on / off lever 61 into the notch 68b (see FIG. 10) of the lever guide 68. Accordingly, the interlocking mechanism 50 is held in the ON position, and the interlocking mechanism 50 can be held in the ON state.

  When interlocking of the shift pedal 24 and the accelerator device 40 is cut off, the interlocking on / off lever 61 is switched to the cutting position OFF located on the other end side of the guide groove 68a. Then, the operating mechanism 60 operates the accelerator interlocking member 51 to be separated from the positioning swinging body 78 by the spring 62, and the engaging mechanism 52 is switched to the disengaged state. Thereby, the interlocking mechanism 50 is turned off, and the operating force of the shift pedal 24 is not transmitted to the operating portion 40a of the accelerator device 40.

  As shown in FIG. 8, the pedal sensor 27 is arranged on the opposite side of the rotary pedal 80 of the speed change pedal 24 from the side where the rotary damper 81 is located, and the rotational operation shaft 27 a of the pedal sensor 27 is The rotating support shaft 80 is linked to the end opposite to the side to which the rotary damper 81 is connected by a connecting screw 83.

[Second Example]
FIG. 13 is a side view of a positioning mechanism 70 having another implementation structure. As shown in this figure, this positioning mechanism 70 has a configuration different from the positioning mechanism 70 of the first embodiment in terms of installation of the rotary damper 81 as compared with the positioning mechanism 70 of the first embodiment. Except for the installation of 81, it has the same configuration as the positioning mechanism 70 of the first embodiment. Next, the installation configuration of the rotary damper 81 will be described.

  A main body case 81 a of the rotary damper 81 is fixed to a damper bracket (not shown) provided in the base body 71. The rotor operating body of the rotary damper 81 is connected to the rotating member 75 in a state of being arranged concentrically with the support shaft 71a of the rotating member 75 as the rotating body of the urging mechanism 74. As a result, the rotary damper 81 gives a swing resistance to the transmission pedal 24 via the rotating member 75 and the interlocking rod 76.

[Another Example]
The object of the present invention can be achieved even if a configuration in which the continuously variable transmission 10 is shifted by a steering drive mechanism that is a combination of a motor and a screw mechanism is used instead of the steering cylinder 26 of the above embodiment. it can. Therefore, the steering cylinder 26 and the steering drive mechanism are collectively referred to as a shift actuator 26.

  The present invention can also be applied to a shift operating device that employs a shift lever instead of the shift pedal 24 of the above embodiment. Therefore, the shift pedal 24 and the shift lever are collectively referred to as a shift operation tool 24.

  The present invention can be applied to a speed change operation device equipped in various work vehicles such as a mower, in addition to the speed change operation device provided in the tractor. Therefore, these tractors, mowers, etc. are collectively referred to as work vehicles.

  The present invention can be applied to a work vehicle provided with a crawler type traveling device instead of the front wheel 3 and the rear wheel 5. Accordingly, the wheels 3 and 5 and the crawler type traveling device are collectively referred to simply as traveling devices 3 and 5.

Side view of the entire tractor Diagram of drive gear Longitudinal side view at the main transmission arrangement portion of the transmission for traveling Cross-sectional plan view at the main transmission arrangement of the drive transmission Block diagram of travel control device Side view of positioning mechanism Side view of interlocking mechanism Plan view of rotary damper and potentiometer placement Perspective view of positioning mechanism and accelerator interlocking member Front view of lever guide Top view of the engagement mechanism in the disengaged state Plan view of the engagement mechanism in the engaged state Side view of positioning mechanism with another implementation structure

Explanation of symbols

3,5 Traveling device 10 Hydrostatic continuously variable transmission 21 Control means 24 Shifting operation tool 26 Shifting actuator 27 Potentiometer 70 Positioning mechanism 75 Rotating body 73 of urging mechanism Spring 74 Energizing mechanism 80 Rotating support shaft 81 of the shifting operation tool Rotary damper 81a Main body case 81c Rotor operation body 82 Support body

Claims (4)

A shift operating device for a work vehicle, comprising a manually operated shift operating tool that shifts a hydrostatic continuously variable transmission that drives a traveling device, and a positioning mechanism that positions the shift operating tool in a neutral state. ,
The positioning mechanism includes an urging mechanism that urges the shifting operation tool to return to a neutral state by a spring, and a rotary damper that is linked to a rotating body of the urging mechanism or a rotation support shaft of the shifting operation tool. A shift operating device for a work vehicle configured as described above.   The hydrostatic continuously variable transmission is operated by the potentiometer for detecting the operation position of the transmission operation tool, the transmission actuator for operating the hydrostatic continuously variable transmission, and the detection information by the potentiometer. The shift operation device for a work vehicle according to claim 1, further comprising a control unit that operates the shift actuator so as to be in a shift state corresponding to a position.   The work gear shift operation device according to claim 2, wherein the rotary damper is linked to one end side of the rotation support shaft of the shift operation tool, and the potentiometer is linked to the other end side of the rotation support shaft.   A rotor operation body of the rotary damper is positioned concentrically with the rotation support shaft of the speed change operation tool and interlocked with the rotation support shaft, and a main body case of the rotary damper rotatably supports the speed change operation tool. The speed change operation device for a work vehicle according to any one of claims 2 to 3, which is fixed to a support.

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