JP2012228938A - Shift operation device of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compactly constitute a detent mechanism and an assist mechanism of a trunnion shaft, while avoiding complication of a structure.SOLUTION: A base part of a main shift lever 13 is provided with a cam 25 for rotating the trunnion shaft by integrally rotating with the main shift lever 13, and a cam arm 26 push-contacting with a cam surface of the cam 25. The cam surface of the cam 25 is provided with a neutral holding recessed part 25a for push-contacting in an engaging shape with the cam arm 26 when the trunnion shaft is a neutral position, an advance time push-contact surface 25b for push-contacting with the cam arm 26 when the trunnion shaft is an advance shift area, and a retreat time push-contact surface 25c for push-contacting with the cam arm 26 when the trunnion shaft is a retreat shift area. An inclination for making push-contact force of the cam arm 26 act so as to assist operation to the speed increase side of the trunnion shaft, is arranged on the advance time push-contact surface 25b and/or the retreat time push-contact surface 25c.

Description

  The present invention relates to a gear shifting operation device for a work vehicle such as a passenger rice transplanter that continuously shifts traveling power using a hydraulic continuously variable transmission.

  A hydraulic continuously variable transmission that continuously changes the driving power in accordance with the rotation position of the trunnion shaft, a shift operation lever that is rotated to a forward shift operation region and a reverse shift operation region via a neutral position; 2. Description of the Related Art A work vehicle including a speed change operation device that rotates a trunnion shaft according to an operation of a speed change operation lever is known (see, for example, Patent Documents 1 and 2).

  Normally, this type of shift operation device holds a position by a detent mechanism that holds the position of the trunnion shaft or the shift operation lever by the engagement force of the cam member or the friction force of the friction member in order to hold the rotational position of the trunnion shaft or the shift operation lever. A position holding mechanism such as a brake mechanism is provided. For example, in the speed change device shown in Patent Document 1, the rotation position of the trunnion shaft and the speed change lever is held steplessly by the brake mechanism in the low speed operation range including the neutral position, and by the detent mechanism in the high speed operation range. It is designed to hold in stages.

JP 2005-193816 A JP 2002-257229 A

  However, in the speed change operation device disclosed in Patent Document 1, when the speed change lever is turned to the speed increasing side, the operation load increases due to the resistance of the trunnion shaft, while the speed change operation lever is turned to the speed reduction side. In this case, since the operation load is reduced by the return force of the trunnion shaft, there is a problem that a good operation feeling cannot be obtained. It is possible to provide an assist mechanism that reduces the operation load when the shift operation lever is turned to the speed increasing side and increases the operation load when the speed change operation is turned to the deceleration side. If a dedicated assist mechanism is provided, the structure becomes complicated.

The present invention has been created in order to solve these problems in view of the above circumstances, and is a hydraulic continuously variable transmission that continuously changes traveling power according to the rotational position of a trunnion shaft. A shift operation lever that is rotated into the forward shift operation region and the reverse shift operation region via the neutral position, and a shift operation device that rotates the trunnion shaft according to the operation of the shift operation lever. The base of the speed change lever is provided with a cam that rotates integrally with the speed change lever and rotates the trunnion shaft, and a cam arm that presses against the cam surface of the cam. In addition, a neutral holding concave portion where the cam arm is pressed in an engaging manner when the trunnion shaft is in the neutral position, a forward pressing surface where the cam arm is pressed when the trunnion shaft is in the forward shift region, and the trunnion shaft It has a reverse pressing surface that the cam arm presses in the speed change range, and assists the operation of the cam arm pressing force toward the acceleration side of the trunnion shaft on the forward pressing surface and / or the reverse pressing surface. It is characterized by providing an inclination to act as described above.
Further, the cam is provided so as to be rotatable coaxially with the rotation support shaft of the speed change operation lever.

According to the first aspect of the present invention, not only can the detent mechanism that holds the trunnion shaft in the neutral position be constituted by the cam and the cam arm provided at the base portion of the speed change operation lever, but also the acceleration force of the trunnion shaft can be increased by the pressing force of the cam arm. Therefore, the trunnion shaft detent mechanism and assist mechanism can be configured compactly while avoiding the complexity of the structure.
According to the invention of claim 2, since the cam is provided coaxially with the rotation support shaft of the speed change operation lever, the assist mechanism that is also used as the detent mechanism can be made more compact.

It is a whole side view of a riding rice transplanter. It is a whole side view of a speed change operation device. It is a principal part front view of a speed change operation apparatus. It is a principal part rear view of a speed change operation apparatus. It is explanatory drawing of neutral fine adjustment operation. It is a side view of the cam and cam arm which show a neutral state. It is a side view of the cam and cam arm which shows the time of forward operation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a riding rice transplanter (work vehicle). The riding rice transplanter 1 is a traveling machine body 2 and a planting work machine 4 connected to a rear portion of the traveling machine body 2 via a lifting link mechanism 3. And is configured.

  The traveling machine body 2 is a passenger-type four-wheel vehicle including left and right front wheels 5 and left and right rear wheels 6. An engine mounting portion 7 on which an engine (not shown) is mounted, a transmission case 8 for shifting engine power, An operation unit 9 on which an operator gets on is provided.

  As shown in FIGS. 2 to 4, a hydraulic continuously variable transmission 10 that functions as a main transmission mechanism of the riding rice transplanter 1 is provided on the left side surface portion of the transmission case 8. The hydraulic continuously variable transmission 10 is configured to continuously change the power transmitted from the engine in accordance with the rotational position of a trunnion shaft (not shown) and to input the shifted power to the transmission case 8. Yes.

  A hydraulic continuously variable transmission 10 according to the present embodiment includes a hydrostatic continuously variable transmission unit configured by combining a swash plate type variable displacement hydraulic pump and a fixed displacement hydraulic motor driven by hydraulic oil supplied from the pump. (HST), and continuously variable transmission in the forward shift region and the reverse shift region via the neutral position is possible.

  The operation section 9 is provided with a driver's seat 11 on which an operator sits, and in front of it is an operation of a steering handle 12 that steers the front wheels 5, a main transmission lever (transmission operation lever) 13 that performs a main transmission operation, and the like. Ingredients are placed. The main transmission lever 13 is connected to the hydraulic continuously variable transmission 10 via a transmission operation device 14, and the trunnion shaft of the hydraulic continuously variable transmission 10 rotates according to the rotation operation of the main transmission lever 13. Is done.

  The main transmission lever 13 is allowed to rotate in the front-rear direction with the first lever support shaft 15 as a fulcrum and in the left-right direction with the second lever support shaft 16 as a fulcrum. It is designed to be rotated along a crank-shaped guide groove 17a. Specifically, the left-right rotation operation at the neutral position, and the front-rear rotation operation in the forward shift operation area secured to extend forward from the right end of the neutral position (speed increase by the front operation, rearward And decelerating in the forward / backward direction in the reverse shift operation area secured so as to extend backward from the left end of the neutral position (acceleration in the backward operation, deceleration in the forward operation). Yes.

  A lever arm 18 is integrally provided at a base end portion of the main transmission lever 13, and the lever arm 18 is supported by the first lever support shaft 15 so as to be rotatable. Directional rotation operation is allowed. Further, the first lever support shaft 15 is provided with a brake mechanism 19 for holding the rotational position of the main transmission lever 13 in the front-rear direction. The brake mechanism 19 of this embodiment includes a pair of friction plates 20 that are rotatably provided on the first lever support shaft 15 so as to sandwich the lever arm 18, a spring member 21 that presses the friction plate 20 against the lever arm 18, and A stopper member 22 for stopping the friction plate 20 is provided, and the rotational position of the main transmission lever 13 in the front-rear direction is held by the frictional force generated between the friction plate 20 and the lever arm 18. It has become.

  The transmission operation device 14 includes a trunnion arm 23, a rod 24, a cam 25, and a cam arm 26. The trunnion arm 23 is provided integrally with the trunnion shaft of the hydraulic continuously variable transmission 10 and is connected to the cam 25 via the rod 24. The length of the rod 24 can be adjusted, and the relative positional relationship between the trunnion arm 23 and the cam 25 can be changed. However, it is difficult to adjust the neutral position of the trunnion shaft, which requires a very small position change. It is.

  The cam 25 is disposed at the base portion of the main transmission lever 13 so as to be interlocked with the rotation operation of the main transmission lever 13 in the front-rear direction. Specifically, it is provided so as to be rotatable with respect to the first lever support shaft 15, and is connected to the lever arm 18 via the accommodation mechanism 27. Accordingly, the cam 25 can rotate the trunnion shaft via the rod 24 and the trunnion arm 23 in conjunction with the rotation operation of the main transmission lever 13 in the front-rear direction. The accommodation mechanism 27 is for allowing a slight relative displacement of the cam 25 with respect to the lever arm 18 when adjusting the neutral position of the trunnion shaft. And a connecting pin 28 that protrudes from the cam 25 and loosely fits in the fool hole 18a.

  The cam arm 26 is an arm member including a roller 29, and is provided on a lever bracket 30 on which the first lever support shaft 15 is protruded so as to be able to rotate back and forth. A spring 31 is interposed between the cam arm 26 and the lever bracket 30, and the roller 29 is brought into contact with the cam surface of the cam 25 when the cam arm 26 rotates toward the cam 25 by the urging force of the spring 31. It comes to be pressed.

  As shown in FIG. 6, a neutral holding recess 25 a is formed on the cam surface of the cam 25. When the trunnion shaft is at the neutral position, the roller 29 of the cam arm 26 presses the neutral holding recess 25a of the cam 25 in an engaging manner to hold the trunnion shaft at the neutral position. That is, the cam 25 and the cam arm 26 constitute a detent mechanism that holds the trunnion shaft in a neutral position.

  In the case where the neutral position of the trunnion shaft is held by the detent mechanism, an adjustment for matching the holding position by the detent mechanism and the neutral position of the trunnion shaft (hereinafter simply referred to as neutral position adjustment of the trunnion shaft) is required. The neutral position of the trunnion shaft can be coarsely adjusted based on the adjustment of the length of the rod 24, but it is necessary to provide a separate fine adjustment mechanism for fine adjustment.

  In the speed change operation device 14 according to the embodiment of the present invention, the detent mechanism that holds the trunnion shaft in the neutral position and the neutral fine adjustment mechanism that finely adjusts the neutral position of the trunnion shaft are combined. Specifically, the rotational fulcrum of the cam arm 26 can be adjusted in position, and the neutral position of the trunnion shaft is finely adjusted based on the position adjustment. In this case, the cam 25 and the cam arm 26 provided at the base portion of the main transmission lever 13 can not only constitute a detent mechanism for holding the trunnion shaft in the neutral position, but also a neutral fine adjustment mechanism for finely adjusting the neutral position of the trunnion shaft. Can be configured.

  In this embodiment, in order to make the position of the rotation fulcrum of the cam arm 26 adjustable, an eccentric nut 32 that is easy to perform a minute displacement operation is used. The eccentric nut 32 used in the present embodiment is rotated with a tool such as a rotation support shaft portion 32a that functions as a rotation support shaft of the cam arm 26, a retaining portion 32b that retains the cam arm 26, and a spanner. , And a screw hole 32d formed so as to be eccentric with respect to the center of the rotation support shaft portion 32a. As shown in FIG. By tightening 33 into the screw hole 32d, it is fixed to the front side of the lever bracket 30 and functions as a pivot of the cam arm 26. Further, the pivot of the pivot shaft 32a is based on the turning operation of the turning operation part 32c. By slightly displacing the center, the neutral position of the trunnion shaft can be finely adjusted. Reference numeral 34 denotes a nut for preventing looseness.

  A procedure for adjusting the neutral position of the trunnion shaft in the shift operating device 14 configured as described above will be described with reference to FIG. When finely adjusting the neutral position of the trunnion shaft, first, the main transmission lever 13 is operated to the neutral position. At this time, the main transmission lever 13 is held at the neutral position by the brake mechanism 19. Further, since the lever arm 18 provided integrally with the base portion of the main transmission lever 13 is connected to the cam 25 via the interchange mechanism 27, even if the cam 25 is displaced during the neutral position adjustment of the trunnion shaft, The main transmission lever 13 is prevented from interlocking.

  Next, the nut 34 and the bolt 33 are loosened, and the eccentric nut 32 is turned to an operable state. Thereafter, the turning operation portion 32 c of the eccentric nut 32 is turned to change the rotation fulcrum position of the cam arm 26. When the rotation fulcrum position of the cam arm 26 is changed, the position of the roller 29 is changed, the cam 25 engaged with the roller 29 is rotated via the neutral holding recess 25a, and the rod 24 and The trunnion shaft is rotated via the trunnion arm 23. When the turning position of the trunnion shaft becomes the neutral position, the turning operation of the eccentric nut 32 is stopped at that angle (adjusted angle), and the eccentric nut 32 is fixed. The eccentric nut 32 is fixed by holding the turning operation portion 32c of the eccentric nut 32 at a predetermined adjusted angle with a spanner, tightening the bolt 33 with another spanner, and then preventing loosening. This is done by tightening the nut 34.

  Next, a configuration for causing a detent mechanism including the cam 25 and the cam arm 26 to function as an assist mechanism will be described with reference to FIGS. 6 and 7.

  In the speed change operation device 14 configured as described above, when the main speed change lever 13 is turned to the speed increasing side, the operation load increases due to the resistance of the trunnion shaft, while the main speed change lever 13 is turned to the speed reduction side. When operating, the operation load is reduced by the return force of the trunnion shaft, and a good operation feeling may not be obtained. In order to solve such a problem, it is proposed to provide an assist mechanism that reduces the operation load when the main transmission lever 13 is rotated to the speed increasing side and increases the operation load when the main transmission lever 13 is rotated to the deceleration side. Is done. However, when a dedicated assist mechanism is provided, there is a problem that the structure becomes complicated. Therefore, in the speed change operation device 14 according to the embodiment of the present invention, the above problem is solved by causing a detent mechanism including the cam 25 and the cam arm 26 to function as an assist mechanism.

  More specifically, the cam surface of the cam 25 has a neutral holding recess 25a in which the roller 29 of the cam arm 26 presses in engagement when the trunnion shaft is in the neutral position, and when the trunnion shaft is in the forward shift region. A forward contact surface 25b to which the roller 29 of the cam arm 26 is pressed and a reverse contact surface 25c to which the roller 29 of the cam arm 26 is pressed when the trunnion shaft is in the reverse shift region are provided. The forward pressing surface 25b and the reverse pressing surface 25c are not parallel to the rotation locus K of the neutral holding recess 25a, but are inclined so as to approach the rotation center of the cam 25 as the distance from the neutral holding recess 25a increases. I have. As shown in FIG. 7, this inclination converts the pressing force A (the urging force of the spring 31) of the cam arm 26 into a force B that tries to rotate the cam 25 in the speed increasing direction. It is possible to reduce the operation load during the rotation operation to the speed increasing side and to increase the operation load during the rotation operation to the deceleration side.

  According to the present embodiment configured as described, the hydraulic continuously variable transmission 10 that continuously changes the traveling power according to the rotational position of the trunnion shaft, the forward shift operation region and the reverse shift via the neutral position. A riding rice transplanter 1 including a main transmission lever 13 that is rotated into an operation area and a transmission operation device 14 that rotates a trunnion shaft in accordance with the operation of the main transmission lever 13. A cam 25 that rotates integrally with the main transmission lever 13 to rotate the trunnion shaft and a cam arm 26 that presses against the cam surface of the cam 25 are provided at the base, and the trunnion shaft is provided on the cam surface of the cam 25. Is a neutral holding recess 25a in which the cam arm 26 is pressed in engagement when the trunnion is in the neutral position, a forward pressing surface 25b in which the cam arm 26 is pressed when the trunnion shaft is in the forward shift region, and the trunnion shaft And a reverse pressing surface 25c against which the cam arm 26 is pressed in the forward shift range, and the pressing force of the cam arm 26 is applied to the trunnion shaft on the acceleration side of the forward pressing surface 25b and / or the backward pressing surface 25c. Since the inclination that acts to assist the operation of the trunnion shaft is provided, the detent mechanism and the assist mechanism of the trunnion shaft can be made compact while avoiding the complexity of the structure.

  Further, since the cam 25 is provided so as to be rotatable coaxially with the rotation support shaft of the main transmission lever 13, the assist mechanism that is also used as the detent mechanism can be made more compact.

DESCRIPTION OF SYMBOLS 1 Riding rice transplanter 2 Traveling machine body 10 Hydraulic continuously variable transmission 13 Main transmission lever 14 Shifting operation device 18 Lever arm 19 Brake mechanism 20 Friction plate 23 Trunnion arm 24 Rod 25 Cam 25a Neutral holding concave portion 25b Pushing surface 25c at the time of advance Reverse contact surface 26 Cam arm 27 Interchange mechanism 28 Connecting pin 29 Roller 31 Spring 32 Eccentric nut 33 Bolt

Claims (2)

A hydraulic continuously variable transmission that continuously changes the driving power in accordance with the rotation position of the trunnion shaft, a shift operation lever that is rotated to a forward shift operation region and a reverse shift operation region via a neutral position; A work vehicle comprising a speed change operation device that rotates a trunnion shaft in response to an operation of a speed change operation lever;
The base of the speed change operation lever is provided with a cam that rotates integrally with the speed change operation lever to rotate the trunnion shaft, and a cam arm that presses against the cam surface of the cam, and the cam surface of the cam has a trunnion shaft. A neutral holding recess in which the cam arm is pressed and engaged in the neutral position, a forward pressing surface to which the cam arm is pressed when the trunnion shaft is in the forward shift region, and a cam arm when the trunnion shaft is in the reverse shift region. And a reverse-contact surface for reverse movement, and a slope that acts on the forward-contact surface and / or reverse-contact surface to assist the operation of the trunnion shaft toward the speed increasing side. A shift operating device for a work vehicle, comprising:   The shift operation device for a work vehicle according to claim 1, wherein the cam is rotatably provided on the same axis as a rotation support shaft of the shift operation lever.

Images