JPH07158666A - Travel transmission structure of working vehicle - Google Patents

Abstract

PURPOSE:To make sudden stop quick at the time of return-operating a speed change lever into the neutral stop position in the travel transmission structure of a working vehicle provided with an actuator for speed-change operating a continuously variable transmission so that the continuously variable transmission for travel is operated into the speed change position corresponding to the operated position of the speed change lever. CONSTITUTION:The travel transmission structure of a working vehicle is provided with an operating sensor 62 for detecting the operation of a speed change lever 41 onto neutral position N side at the operating speed faster than the operating speed of a continuously variable transmission 1 by an actuator 55, and an operating means 63 for rapidly operating transmission cutoff to a travel transmission system on the upper or lower side of the continuously variable transmission 1, preceding the actuator 55 when the speed change lever 41 is going to be return-operated rapidly onto the neutral stop position N-side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling power transmission structure of a work vehicle using a belt type or a hydrostatic type continuously variable transmission for traveling.

[0002]

2. Description of the Related Art When a gearshift operating member such as a gearshift lever or a gearshift pedal is mechanically linked to a gearshift operating portion of a continuously variable transmission for traveling as described above, operation resistance from the continuously variable transmission causes The operation of the speed change operation tool is often heavy.

Therefore, as disclosed in, for example, Japanese Unexamined Patent Publication No. 4-175562, an auxiliary operating force is applied to the speed change operation tool along the operation direction of the speed change operation tool (3 in FIG. 1 of the publication). By providing the actuator (8 in FIG. 1 of the above publication), the continuously variable transmission (1 in FIG. 1 of the above publication) is lightly operated to the gear shift position corresponding to the operation position of the gear shift operation tool. Some are configured to.
Further, an actuator for directly shifting the continuously variable transmission is provided so that the potentiometer detects the operation position of the gear shifting operation device and the continuously variable transmission is operated at the gear shift position corresponding to the detected position of the potentiometer. There are also things.

[0004]

If the actuator is provided with an auxiliary operating force or the actuator is used to directly shift the continuously variable transmission as described above, the operation of the shift operating tool is light. However, since the operating speed of the continuously variable transmission by this actuator is limited, it is actually difficult to say a quick gear shift operation of the continuously variable transmission by the gear shifting operation tool. .

Therefore, when the continuously variable transmission is operated to a certain shift position by the gearshift operation tool and the vehicle is traveling, it is difficult to quickly return the gearshift operation tool to the neutral stop position to make an abrupt stop. Sometimes became. The present invention provides a traveling power transmission structure for a work vehicle configured such that a continuously variable transmission for traveling is speed-changed by a speed-change operating tool and an actuator, so that a quick stop can be easily performed by quickly returning the speed-changing operating tool to a neutral stop position. It is intended to be configured to do.

[0006]

A feature of the present invention is that the traveling power transmission structure for a work vehicle as described above is configured as follows. That is, the continuously variable transmission, the manually operated gear shift operation tool, and the continuously variable transmission are operated so that the continuously variable transmission is operated at the gear shift position corresponding to the operation position of the gear shift operation tool. In addition to an actuator to operate, the operation sensor that detects that the speed change operation tool has been operated to the neutral stop position side at an operation speed faster than the operation speed of the continuously variable transmission by the actuator, and the operation sensor Based on this, there is provided operation means for rapidly performing transmission cutoff operation of the traveling transmission system on the upper side or the lower side of the continuously variable transmission.

[0007]

According to the present invention, when the operator operates the continuously variable transmission to a certain gear shift position by the gear shift operation tool, the operator tries to quickly return the gear shift operation tool to the neutral stop position. To do. In this case, the return operation of the gear shift operation tool by the operator is detected by the operation sensor, and the travel transmission system is rapidly transmitted by the operation means prior to the return operation to the neutral stop position side of the continuously variable transmission by the actuator. The aircraft will be shut off and the aircraft will make a sudden stop. Then, after a short delay, the continuously variable transmission is brought back to the neutral stop position by the actuator.

[0008]

As described above, in the traveling power transmission structure of the working vehicle in which the continuously variable transmission for traveling is operated to change the speed by the operation gear and the actuator, the operation gear is moved to the neutral stop position during traveling. If you want to perform a quick return operation and make a sudden stop, you can perform a sudden stop of the aircraft by cutting off the transmission of the traveling transmission system at another position prior to the continuously variable transmission,
It was possible to improve the speed change operability of the work vehicle.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 7 shows a combine vehicle, which is an example of a work vehicle,
1 shows a structure inside a transmission case 8 of a traveling system, in which power from an engine (not shown) is passed through a belt transmission mechanism (not shown) equipped with a tension clutch to drive the belt-type continuously variable transmission 1. It is transmitted to the input pulley 2. The power from the output shaft 3 of the continuously variable transmission 1 is transmitted to the first transmission shaft 5 and the input gear 6 of the hydraulic forward clutch FC, and from this input gear 6 to the input gear 9 of the hydraulic reverse clutch RC. The output gears 7 and 10 of the forward clutch FC and the reverse clutch RC are transmitted and mesh with the input gear 12 of the second transmission shaft 11.

With the above-mentioned structure, when hydraulic oil is supplied to the forward clutch FC and is entered and operated, the power from the first transmission shaft 5 is in the forward state via the input gear 6, the forward clutch FC and the output gear 7. Is transmitted to the second transmission shaft 11.
On the contrary, when hydraulic oil is supplied to the reverse clutch RC and the reverse clutch RC is turned on and operated, the power from the first transmission shaft 5 causes the input gear 6,
9, the reverse clutch RC and the output gear 10 are transmitted to the second transmission shaft 11 in the reverse reverse rotation state.

A shift gear 13 is slidably fitted on the second transmission shaft 11 in a spline structure, while a high speed gear 15 and a medium speed gear 16 are mounted on the third transmission shaft 14 on the third transmission shaft 14.
Also, the low speed gear 17 is fixed. As a result, the shift gear 13 is slid and operated to engage with the high speed gear 18, the medium speed gear 16 or the low speed gear 17 that meshes with the high speed gear 15 to shift the power to three stages of high, medium and low. Is transmitted to the transmission gear 28.

Right and left side gears 21 are relatively rotatably fitted over the support shaft 20 supporting the transmission gear 28, and the input gears 23 of the left and right axles 22 are constantly meshed with the left and right side gears 21. . A multi-plate type side brake 26 is provided between the left and right side gears 21 and the transmission case 8 at both left and right ends of the support shaft 20.
7, the side gear 21 is urged toward the occlusal side with the transmission gear 28.

When the left and right side gears 21 are engaged with the transmission gear 28 by the above structure, the power from the third transmission shaft 14 is transmitted through the transmission gear 28 and the left and right side gears 21 to the left and right crawler type traveling devices. After being transmitted to 24, the aircraft goes straight. Then, when the right or left side gear 21 is operated to be separated from the transmission gear 28 and the side brake 26 is pressed and operated by the side gear 21, one traveling device 24 is braked and the machine body makes a pivotal turn.

A gear pair 25 having a pair of large and small gears is fitted onto the first transmission shaft 5 so as to be rotatable relative to each other, and the gear on the large side of the gear pair 25 meshes with the output gear 7 of the forward clutch FC. is doing. A shift gear 43 having a spline structure is slidably fitted onto an output shaft 42 that supports an output pulley 4 that transmits power to a mowing portion (not shown) at the front of the machine body. As a result, the shift gear 43 is slid and engaged with the large and small gears of the gear pair 25, so that the power to the mowing section can be shifted between high and low stages.

(2) Next, a turning structure in which the left and right side gears 21 are independently slid is described. Figure 8
As shown in FIG. 5, the hydraulic oil from the pump 29 is supplied to the hydraulic cylinders 31 for the left and right side gears 21 via the flow priority valve 32 and the first switching valve 30, and the flow priority valve 32 and the first switching valve 30 are supplied. A variable relief valve 33 is connected between and. An operating lever 34 for turning operation is provided in the control section of the aircraft,
The operating lever 34, the first switching valve 30, and the variable relief valve 3
3 and 3 are mechanically linked via a push-pull wire 35 and a wire 36. In the state shown in FIG. 8, the operating lever 34 is operated to the neutral position N, the left and right side gears 21 are engaged with the transmission gear 28, and the power of the transmission gear 28 is transmitted to the left and right traveling devices 24. The aircraft is going straight.

When the operating lever 34 is operated to the right or left first turning position R1, L1 from this state, for example, the first switching valve 30 is switched and hydraulic oil is supplied to one hydraulic cylinder 31, and the right or left hydraulic cylinder 31 is operated. The left side gear 21 is slid by the operation arm 37 and separated from the transmission gear 28,
The side brake 26 is contacted. In this case, since the variable relief valve 33 is in a state close to the fully opened state, the right or left side gear 21 lightly presses the side brake 26, the one traveling device 24 is lightly braked, and the aircraft gently moves to the right. Or turn left and go.

Then, the operation lever 34 is moved to the right or left first
The second turning position R2, which is right or left from the turning positions R1, L1
As the valve is operated toward the L2 side, the variable relief valve 33 is gradually throttled and the side gear 21 gradually presses the side brake 26 strongly. As a result, the braking force applied to the right or left traveling device 24 from the side brakes 26 gradually increases, and the aircraft turns right or left. Then, the braking force of the side brake 26 becomes maximum at the right or left second turning position R2, L2, and the operation lever 34 is moved between the first turning position R1, L1 and the second turning position R2, L2. The braking force of the side brake 26 can be arbitrarily changed by operating the.

(3) Next, the belt type continuously variable transmission 1 and its gear shifting operation structure will be described. As shown in FIG. 2, the input shaft 44 to which the input pulley 2 is fixed is provided with a first split pulley 45, and the output shaft 3 is provided with a second split pulley 46.
Transmission belt 4 across the first and second split pulleys 45, 46
It is winding 7. First and second split pulleys 45, 46
Is composed of a pulley portion 48 fixed to the input shaft 44 and the output shaft 3 with a spline structure, and a pulley portion 49 movable in the axial direction of the input shaft 44 and the output shaft 3, and the second split pulley 46. The moving pulley portion 49 is urged by the spring 50 toward the fixed pulley portion 48, and the moving pulley portion 49 is moved to the fixed pulley portion 48 in proportion to the increase in the load on the output shaft 3 side. A pushing cam mechanism 51 is provided.

As shown in FIGS. 2 and 3, a ring member 52 is externally fitted to a moving pulley portion 49 of the first split pulley 45 via a bearing, and a pair of pins 52a are fixed to the ring member 52. However, the ring member 52 is prevented from rotating by entering the recess 54 on the case side of the continuously variable transmission 1. A cylindrical cam member 53 is externally fitted to the input shaft 44 via a bearing, and a pair of concave portions composed of a linear bottom portion 53a and a pair of left and right symmetrical inclined surfaces 53b are formed in the cam member 53. Therefore, the roller 52b of the pin 52a of the ring member 52 is inserted into the pair of recesses of the cam member 53.

In the state shown in FIGS. 2 and 3, the moving pulley portion 49 of the first split pulley 45 is farthest from the fixed pulley portion 48 on the left side of the drawing, and the second split pulley 46 is shown.
Of the moving side pulley portion 49 of the fixed side pulley portion 4
It is the state of the lowest speed position closest to 8. Then, when the cam member 53 is rotated to the right or left from this state, the moving side pulley portion 49 of the ring member 52 and the first split pulley 45 is moved to the fixed side pulley portion 48 side via the inclined surface 53b. By pushing and approaching, the winding radius of the transmission belt 47 on the first split pulley 45 increases, and along with this, the moving-side pulley portion 49 of the second split pulley 46 becomes the fixed-side pulley. As it moves away from the portion 48 to the right in the drawing, the continuously variable transmission 1 is operated to shift to the high speed side.

Next, the shift operation of the continuously variable transmission 1 by the shift lever 41 (corresponding to a shift operation tool) will be described. As shown in FIGS. 1 and 2, the boss member 38 is fixed to the end of the cam member 53 on the outside of the continuously variable transmission 1, and the speed change lever 41 is swingable right and left around the horizontal axis P1 of the boss member 38. The fan-shaped gear 40 is fixed to the boss member 38, and a motor 55 (corresponding to an actuator) that rotationally drives the fan-shaped gear 40 is provided. Then, the pin 38b of the arm 38a of the boss member 38
Is inserted into the opening 40a of the fan gear 40, and the pair of rubber-like pressure-sensitive sensors 56 are connected to the pin 38 of the arm 38a.
It is fixed to the fan-shaped gear 40 so as to sandwich b.

The state shown in FIG. 1 is a state in which the transmission lever 41 is being operated to the neutral stop position N, and corresponds to the state shown in FIGS. 2 and 3. From this state, the shift lever 41
When the cam member 53 is rotated by operating the forward movement side F and the backward movement side R, the pin 38b of the arm 38a is pressed by the pressure sensitive sensor 56 by this operation, and the pressure sensitive sensor 5
A signal from the motor 55 causes the boss member 38 and the fan gear 40 to rotate in the operating direction of the speed change lever 41.
Is operated, and the continuously variable transmission 1 is operated to shift to the high speed side. When the operation of the speed change lever 41 is stopped at the desired operation position, the motor 55 also stops, and the speed change lever 41 and the continuously variable transmission 1 are held at this operation position by the motor 55.

(4) Next, the linkage structure of the continuously variable transmission 1, the forward and reverse clutches FC and RC will be described. Figure 8
As shown in FIG. 5, the hydraulic oil of the pump 29 is supplied to the forward clutch FC and the reverse clutch RC via the flow priority valve 32 and the second change valve 39, and the second change valve 39 has the forward clutch FC and the reverse clutch. Neutral stop position 39N for draining hydraulic oil from RC and cutting both
It has three positions: a forward drive position 39F for supplying hydraulic oil to the forward clutch FC to enter and operate it, and a reverse drive position 39R for supplying hydraulic oil to the reverse clutch RC to enter and operate it.

As shown in FIGS. 4, 5 and 6, the second switching valve 3
The operation plate 5 is attached to the operation shaft 57 for switching 9 to the above-mentioned three positions.
8 is fixed, and a long hole 58a is opened in the operation plate 58. On the other hand, as shown in FIG. 1, a push-pull wire 60 is connected to the fan gear 40 on the side of the continuously variable transmission 1, and the pin 60a at the tip of the push-pull wire 60 is inserted into the elongated hole 58a of the operation plate 58. Has been inserted. Then, one spiral spring 59 is wound around the operation shaft 57, and the spiral spring 59 sandwiches the pin 58b fixed to the operation plate 58 and the pin 60a of the push-pull wire 60.

As shown in FIG. 8, a lever guide 61 is provided for the speed change lever 41, and the lever guide 61 corresponds to the neutral stop position N. An operation path 61F on the forward side F that faces the front side, and an operation path 6 on the reverse side R that faces the rear side of the aircraft from the neutral path 61N and is opposite to the forward side F.
It is configured with 1R.

(5) Next, the operation of the continuously variable transmission 1, the forward and reverse clutches FC and RC will be described. With the above structure, as shown in FIGS. 1 and 8, the speed change lever 41 is moved to the neutral path 61N of the lever guide 61 (neutral stop position N).
When it is operated to the center, the continuously variable transmission 1 is operated to the lowest speed position as shown in FIGS. 2 and 3. And
In this state, the second switching valve 39 moves to the neutral stop position 39N.
Operated by the forward clutch FC and the reverse clutch RC
The aircraft has been turned off and the aircraft has stopped.

From this state, the transmission lever 41 is moved to the neutral path 6
In 1N, when the operation is performed to the operation side 61F side of the forward movement side F (upper surface of FIG. 8) and the operation is started to the forward movement side F along the operation passage 61F, the motor 55 and the fan are interlocked with the operation of the shift lever 41. The mold gear 40 starts to move forward F,
The push-pull wire 60 starts to be pushed. Then, by the operation of the push-pull wire 60, the second switching valve 39 is switched from the neutral stop position 39N to the forward position 39F via the spiral spring 59 and the operation plate 58.

As described above, when the shift lever 41 is operated to the forward side F to the extent that the second switching valve 39 is switched to the forward position 39F, the bottom portion 53 of the cam member 53 shown in FIG.
The end of a (the boundary with the inclined surface 53b) is the ring member 5
Since the cam member 53 rotates to such an extent that it reaches the second roller 52b, the continuously variable transmission 1 is left in the lowest speed position. Then, the second switching valve 39 moves to the forward position 3
When the speed change lever 41 is operated to the high speed side of the forward drive side F along the operation path 61F from the state of being switched to 9F, the motor 55 and the fan-shaped gear 40 are also operated to the high speed side of the forward drive side F and the cam is operated. When the member 53 is rotationally operated, one of the inclined surfaces 53b of the cam member 53 causes the ring member 52 and the pulley portion 49 on the moving side of the first split pulley 45 shown in FIG.
The continuously variable transmission 1 is pushed toward the high-speed side by being pushed toward the fixed pulley portion 48 side.

In this case, the second switching valve 39 is moved to the forward position 39.
Since the shift lever 41 is further operated to the forward side F after the switching operation to F, the shift lever 41 is operated more than the switching operation amount of the second switching valve 39. As described above, when the shift lever 41 is further moved to the forward side F after the second switching valve 39 has been switched to the forward position 39F, the operation plate 58 is moved downward by the push-pull wire 60 in FIG. 39 is operated to the forward position 39F),
From the state in which the operation plate 58 cannot be displaced further downward, the push-pull wire 60 is further pushed downward in the plane of the paper. In such a state, the spiral spring 59 opens downward in the plane of the paper and is pushed. Pull wire 6
The movement of 0 to the lower side of the paper (advancing side F) is allowed.

Contrary to the above state, the gear shift lever 41 is operated from the state shown in FIG. 8 to the operation route 61R side of the reverse side R in the neutral route 61N (downward in the plane of FIG. 8), and along the operation route 61R. When the operation to the reverse side R is started, the motor 55 and the fan gear 40 are interlocked with the operation of the shift lever 41.
Starts to operate on the reverse side R, and the push-pull wire 60 starts to be pulled. The operation of the push-pull wire 60 causes the second switching valve 39 to be switched from the neutral stop position 39N to the reverse position 39R via the spiral spring 59 and the operation plate 58. In this case as well, As in the case of the forward drive side F, the continuously variable transmission 1 remains in the lowest speed position.

From this state, the transmission lever 41 is moved to the operation path 6
When operated toward the high speed side of the reverse side R along 1R, the motor 55 and the fan gear 40 are also operated to the high speed side of the reverse side R, the cam member 53 is rotationally operated, and the other inclination of the cam member 53 is increased. The ring member 52 and the first split pulley 4 are formed by the surface 53b.
5, the pulley portion 49 on the moving side is pushed toward the pulley portion 48 on the fixed side, and the continuously variable transmission 1 is shifted to the high speed side. Then, in this state, when the second switching valve 39 is switched to the reverse position 39R and then the shift lever 41 is further operated to the reverse side R, the second switching valve 3
Although the shift lever 41 is operated by more than the switching operation amount of 9, the spiral spring 59 is not operated after the operation plate 58 is operated upward in the drawing in FIG. 4 (the reverse position 39R of the second switching valve 39). Open the upper part of the page and push-pull wire 6
Therefore, the movement of 0 to the upper side of the paper surface (reverse side R) is allowed.

(6) Next, a structure for suddenly stopping the airframe when moving forward will be described. As shown in FIGS. 1 and 8, a rubber-like pressure sensor 62 (corresponding to an operation sensor) is embedded in the surface of the grip portion 41a at the upper end of the shift lever 41 on the front side of the machine body. Then, as shown in FIG. 8, between the pump 29 and the flow priority valve 32, the hydraulic oil from the pump 29 is supplied to the flow priority valve 32 side to supply position 63a, and the hydraulic oil is drained from the flow priority valve 32 side. It is provided with an electromagnetically operated third switching valve 63 (corresponding to operating means) which is switchable between two positions of the oil draining position 63b and biased toward the supply position 63a.

During forward movement by operating the speed change lever 41 along the operation path 61F of the lever guide 61 toward the forward side F, the operator holds the speed change lever 41 at the neutral stop position N while gripping the grip portion 41a of the speed change lever 41. Therefore, the motor 55 is operated in response to this operation, and the continuously variable transmission 1 is operated to the low speed side.
Is operated to the neutral stop position N, the continuously variable transmission 1 is operated to the lowest speed position, the push-pull wire 60 operates the first switching valve 39 to the neutral stop position 39N, and the forward clutch FC is disengaged to operate the vehicle body. Will stop.

In this case, when the worker quickly starts to operate the speed change lever 41 to the neutral stop position N while gripping the grip part 41a of the speed change lever 41, the force applied to the grip part 41a from the operator's hand is applied to the pressure sensor 62. Is detected by the control device 64, and the control device 64 quickly switches the third switching valve 63 to the oil discharge position 63b. As a result, the shift lever 4
Before 1 returns to the neutral stop position N, the forward clutch FC is quickly disengaged by the third switching valve 63, and the airframe is stopped.

(7) Next, the structure of the transmission lever 41 near the pressure-sensitive sensor 56 of the fan gear 40 will be described. As shown in FIGS. 9 and 10, a plate member is bent to form a holding member 65, and the holding member 65 is fixed to the sector gear 40 by a bolt 66, and the rectangular block-shaped pressure sensitive sensor 56 is held. The member 65 is held by the member 65 at a position slightly inserted into the opening 40 a of the fan gear 40. The holding member 65 is provided with a notch 65a at the tip thereof for embracing the pressure sensitive sensor 56, and the notches 65a of both the holding members 65 are formed in the opening 4 of the fan-shaped gear 40.
0a and the pin 38b on the side of the speed change lever 41 are positioned to face each other.

In this case, the holding member 65 as shown in FIG.
The depth A1 of the notch 65a is set to be larger than the depth A1 of the pressure sensor 56 into the opening 40a, and the pin 38b is pressed by the pressure sensor 56 in accordance with the operation of the shift lever 41. When this is done, the pin 38b comes into contact with the portion of the notch 65a of the holding member 65. The holding member 65 is fixed to the fan gear 40 via the bolts 66 by a pair of elongated holes 65b provided in the holding member 65, and the pressure sensor 56 and the holding member 65 for the opening 40a. Is configured so that the position of can be adjusted in the left-right direction of the paper surface of FIG.

[First Embodiment] In addition to the structure of the pressure-sensitive sensor 62 shown in FIGS. 1 and 8, a push-on push-off type stop beside the grip portion 41a of the speed change lever 41 as shown in FIG. The switch 41b is provided, and the limit switch 67 for detecting that the stop switch 41b is being pushed is provided.
In response to the signal from the third switching valve 63 in FIG.
3b may be provided so that it can be switched. As a result, the stop switch 41b of the speed change lever 41 during traveling
If is pressed, the third switching valve 63 is quickly switched to the oil discharge position 63b, and the machine body suddenly stops.

Instead of the pressure sensitive sensor 62 shown in FIGS. 1 and 8, the pressure sensitive sensor 56 for the motor 55 shown in FIGS.
May be used as the operation sensor of the present invention. In this case, when the gear shift lever 41 is strongly returned to the neutral stop position N side and the pin 38b of the arm 38a is strongly pressed by the pressure sensor 56, based on this, the third switching valve 6 of FIG.
3 is switched to the oil discharge position 63b.

[Second Embodiment] In the embodiment shown in FIGS. 1 and 8, the shift lever 41, the fan gear 40, and the second switching valve 39 are connected by the push-pull wire 60. 41 and the second switching valve 39 may be interlockingly connected by a bell crank (not shown), a connecting rod (not shown), an operation plate 68 shown in FIG. in this case,
A planar operation plate 68 as shown in FIG. 12 is slidably supported on the lever guide 61 in the vertical direction of the drawing,
A limit switch 70 is provided for urging the operation plate 68 toward the lever guide 61 (downward in the plane of FIG. 12) by a pair of springs 69 to detect the movement of the operation plate 68 upward in the plane of paper.

Thus, as shown in FIG. 12, the center position of the neutral path 61N in the lever guide 61 is set as the neutral stop position N of the speed change lever 41, and the speed change lever 41 is operated on the forward side F or the reverse side R of the neutral path 61N. Route 6
The second switching valve 39 is configured to be switched to the forward drive position 39F or the reverse drive position 39R when operated to the end portions of 1F and 61R, and when the speed change lever 41 is located in the neutral path 61N, the limit is set. The non-detection signal of the switch 70 causes the third switching valve 63 of FIG. 8 to be operated to the oil drainage position 63b.

Next, when the speed change lever 41 is operated to the operation path 61F, 61R on the forward side F or the reverse side R, the operation plate 68 is pushed upward by the speed change lever 41, and the limit switch 70 is detected. The third signal shown in FIG.
The switching valve 63 is configured to be switched to the supply position 63a. In addition to the configuration shown in FIG. 12 above, the pressure sensor 62 of FIGS. 1 and 8 and the stop switch 4 of FIG.
1b and the limit switch 67 are provided.

[Third Alternative Embodiment] [First Embodiment] [First Embodiment]
The configuration shown in FIG. 13 may be added to the other embodiment] and the [second embodiment]. As shown in FIG. 13, a brake pedal 71 that allows the left and right side brakes 26 to be simultaneously and forcibly operated on the braking side is provided.
A limit switch 72 for detecting the stepping operation of 1 is provided,
A wire 74 connects an operation arm 73 capable of forcibly operating the variable relief valve 33 to the fully open side with a brake pedal 71. As a result, when the brake pedal 71 is stepped on, the third switching valve 63 is quickly switched to the oil drainage position 63b based on the detection of the limit switch 72,
The variable relief valve 33 is forcibly operated to the fully open side by the operation arm 73.

[Fourth Embodiment] [First Embodiment] [First Embodiment]
Alternative Embodiment] In [Second Alternative Embodiment] and [Third Alternative Embodiment], instead of the configuration in which the second switching valve 39 for the forward and reverse clutches FC and RC is operated to the neutral stop position 39N, it is continuously variable. The tension clutch on the upper side of the transmission 1 is disengaged, and the shift gear 13 on the lower side of the continuously variable transmission 1 (see FIG. 7) is operated to a neutral stop position to make a sudden stop of the aircraft. May be. Further, the belt type continuously variable transmission 1 may be configured as a continuously variable transmission 1 using a tapered cone, and in this case, the lowest speed position of the continuously variable transmission 1 becomes a neutral stop position to which power is not transmitted. May be set as follows. Further, the continuously variable transmission 1 may be configured as a hydrostatic type that can be operated to shift to a neutral stop position, a forward drive side and a reverse drive side. Further, the transmission lever 41 and the continuously variable transmission 1 are completely separated, the operation position of the transmission lever 41 is detected by a potentiometer (not shown), and the continuously variable transmission 1 is operated by the actuator. It may be configured to operate to the shift position corresponding to.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a side view near a continuously variable transmission and a shift lever.

FIG. 2 is a vertical sectional rear view of the continuously variable transmission.

FIG. 3 is a plan view of a cam member and a ring member in the continuously variable transmission.

FIG. 4 is a front view showing an operating portion and a flexible structure of the second switching valve.

FIG. 5 is a vertical cross-sectional side view showing the operation portion and the accommodation structure of the second switching valve.

FIG. 6 is a cross-sectional plan view showing an operating portion and a flexible structure of the second switching valve.

FIG. 7 is a schematic diagram showing a transmission structure in a mission case.

FIG. 8 is a diagram showing a hydraulic cylinder for left and right side gears, a first switching valve and a variable relief valve, a second switching valve, hydraulic circuits such as forward and reverse clutches, and a lever guide of a shift lever.

FIG. 9 is a cross-sectional plan view around the pressure sensor of the fan gear.

FIG. 10 is a perspective view around a pressure sensor of a fan gear.

FIG. 11 is a rear view of the vicinity of the grip portion of the shift lever according to the first alternative embodiment.

FIG. 12 is a plan view of the vicinity of a lever guide in a second alternative embodiment.

FIG. 13 is a hydraulic circuit diagram in a third alternative embodiment.

[Explanation of symbols]

 1 continuously variable transmission 41 gear shift operation tool 55 actuator 62 operation sensor 63 operation means N neutral stop position

Claims (1)

[Claims] 1. A continuously variable transmission (1) for traveling, an artificially operated shift operating tool (41), and the continuously variable transmission at a shift position corresponding to an operating position of the shift operating tool (41). The continuously variable transmission (1) so that the transmission (1) is operated.
And an actuator (55) for performing a gear shift operation of the continuously variable transmission (1) by the actuator (55) at a faster operation speed than the operation speed of the continuously variable transmission (1). ) Side operation sensor (62) for detecting that it has been operated, and based on the detection of this operation sensor (62), the upper or lower traveling transmission system of the continuously variable transmission (1) is rapidly changed. A traveling power transmission structure for a work vehicle, which is provided with an operation means (63) for performing a transmission interruption operation.