JPH07149159A - Travelling transmission structure for work vehicle - Google Patents

Abstract

PURPOSE:To perform variable speed operation of a continuously variable- transmission without any trouble even at temporary stop time, and also facilitate a switching operation to a backward travelling condition, for example, when a vehicle frame is temporarily stopped and the operation is switched from a forward travelling condition to the backward travelling condition. CONSTITUTION:A travelling transmission structure for a work vehicle is formed such that engine power is transmitted from a continuously variable transmission to a travelling device through a forward/backward travelling switching device on the lower side, and provided with a stop operation mechanism 53 to move a switching operation tool 47 for the forward/backward travelling switching device to a neutral stop position N when a stop operation tool 55 for a vehicle frame stop operation is operated.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As an example of a continuously variable transmission for traveling as described above, a pair of pulley portions are opposed to each other so that they can be moved close to and away from each other to form a split pulley, and a transmission belt is provided across the pair of split pulleys. BACKGROUND ART There is a belt-type continuously variable transmission that is configured to perform a gear shift operation by winding and changing a gap between pulley portions of a split pulley to change a winding radius of a transmission belt. Since such a continuously variable transmission is not provided with a reverse rotation function, there are many work vehicles in which a forward / reverse switching device of a gear shift type or a hydraulic clutch type is arranged in series to the continuously variable transmission.

In the case of this work vehicle, a main clutch is provided between the continuously variable transmission and the forward / rearward movement device and the engine, and when the clutch pedal is depressed, the main clutch is disengaged. Some are configured to be able to pause.

[0004]

As described above, the main clutch is provided on the upper side of the continuously variable transmission and the forward / rearward traveling device,
When the main clutch is disengaged, the aircraft temporarily stops, but both the continuously variable transmission and the forward-reverse shifting device stop without power being transmitted. In this case, the continuously variable transmission is capable of gear shifting operation in a transmission state in which power is transmitted from the upper hand side and power is shifted to the lower hand side due to its mechanical property.

Therefore, when the operator mistakenly attempts to shift the continuously variable transmission by force while the main clutch is disengaged and the continuously variable transmission is stopped as described above, the continuously variable transmission is changed. An unreasonable load may be applied to the gear shift operation system, resulting in damage to the gear shift operation system. The present invention relates to a traveling power transmission structure for a work vehicle in which a continuously variable transmission and a forward / rearward movement device are arranged in series, and when a vehicle body is temporarily stopped, an operator mistakenly attempts to perform a gear shift operation of the continuously variable transmission. The purpose is to prevent situations that would damage the system.

[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. In other words, the power of the engine is transmitted from the continuously variable transmission to the traveling device via the forward / reverse switching device on the lower side, and the operation portion for switching operation of the forward / reverse switching device and the artificial operation are performed. In cooperation with the switching operation tool, the switching operation tool allows the forward / reverse switching device to be switched between the forward position and the reverse position, and also includes a stop operation tool that is artificially operated to stop the aircraft. A stop operation mechanism is provided for operating the switching operation tool at a neutral stop position where power is not transmitted by the forward / reverse switching device, in conjunction with the operation of the stop operation tool to the stop operation side.

[0007]

With the configuration of the present invention, for example, as shown in FIG. 1A, when the switching operation tool 47 is operated to the forward movement position F and the stop operation tool 55 is operated to the stop operation side during the forward movement, As shown in FIG. 1B, the switching operation tool 47 is forcibly returned to the neutral stop position N by the action of the stop operation mechanism 53. As a result, the operating portion of the forward / reverse switching device is also operated to the neutral stop position via the switching operation tool 47, power is shut off in the forward / reverse switching device, and the machine body stops.
In this case, for example, as shown in FIG. 4, since the forward / reverse switching device 44 is located on the lower side of the continuously variable transmission 2, even if the power is cut off in the forward / reverse switching device 44, the power from the engine is not supplied. It is input to the continuously variable transmission 2, and the power from the continuously variable transmission 2 is transmitted to the forward / reverse switching device 44 side. Therefore, if the operator tries to shift the continuously variable transmission 2 in the stopped state of the machine body, the shifting operation of the continuously variable transmission 2 can be performed without any trouble.

In a work vehicle such as the present invention, work may be carried out by repeating forward and backward movements. In such a case, the aircraft is once stopped from the forward movement state, and then the switching operation tool is moved backward from the forward movement position. Switching to the position is performed, and the reverse state is entered. Therefore, with the configuration of the present invention, in the case of the work of repeating forward and backward movements as described above, the stop operation tool is operated in the state where the switching operation tool 47 is operated to the forward movement position F as shown in FIG. When 55 is operated to the stop operation side, the switching operation tool 47 at the forward movement position F
Will be returned to the neutral stop position N and the aircraft will stop. Accordingly, when the switching operation tool 47 is operated to the reverse position R after the airframe is stopped, the switching operation tool 47 may be operated from the neutral stop position N intermediate between the forward drive position F and the reverse drive position R to the reverse drive position R. Rather than switching the switching operation tool 47 from the forward drive position F to the reverse drive position R all at once, the switching operation tool 4 is operated.
7 can be easily switched to the reverse position R.

[0009]

As described above, the forward / reverse switching device on the lower side of the continuously variable transmission is operated to the neutral stop position so as to temporarily stop the machine body. If you try to shift gears, you can perform gear shifting without any problems, so you can prevent damage to the gear shifting operation system of the continuously variable transmission due to unreasonable load. It was possible to improve the durability of.

Further, when the forward and backward movements are repeated, the switching operation tool is returned to the neutral stop position with the temporary stop operation of the machine body, so that the switching operation tool can be easily switched to the forward movement position or the reverse movement position after this. As a result, it is possible to improve the operability of the switching operation tool when repeating forward and backward movements.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 4 shows the structure inside the transmission case 1 of the traveling system of the combine, which is one of the work vehicles, in which the power from the engine (not shown) has a belt transmission mechanism (not shown) equipped with a tension clutch. (1) to the input pulley 3 of the belt type continuously variable transmission 2. The power from the output shaft 4 of the continuously variable transmission 2 is transmitted to the reaper (not shown) via the first transmission shaft 5, the second transmission shaft 6 and the output pulley 7.

A forward gear 8 is fitted onto the second transmission shaft 6 so as to be rotatable relative to the second transmission shaft 6, an input gear 12 of the third transmission shaft 11 is meshed with the forward gear 8, and a shift gear 10 is attached to the second transmission shaft 6.
Is fitted with a spline structure so that it can be slid. The reverse gear 9 is fitted onto the first transmission shaft 5 so as to be relatively rotatable, and the reverse gear 9 is attached to the input gear 13 of the third transmission shaft 11.
Is occluded. With the above structure, when the shift gear 10 is engaged with the forward gear 8, the power of the second transmission shaft 6 is transmitted to the third transmission shaft 11 in the forward movement state. Conversely, when the shift gear 10 is engaged with the reverse gear 9, the power of the second transmission shaft 6 is transmitted to the third transmission shaft 11 via the reverse gear 9 in the reverse reverse state. As described above, on the lower side of the continuously variable transmission 2, the gear shift type forward / reverse switching device 44 is configured.

A first high speed gear 16 is fitted onto the third transmission shaft 11 so as to be relatively rotatable, and a shift gear 14 is fitted on the third transmission shaft 11 so as to be slidable by a spline structure. On the other hand, a second high speed gear 17, a medium speed gear 18, and a low speed gear 19 that are in mesh with the first high speed gear 16 are fixed to the fourth transmission shaft 15. As a result, the shift gear 14 is slid to operate the first high speed gear 16, the medium speed gear 18, and the low speed gear 1.
By engaging with the gear 9, the power from the third transmission shaft 11 is transmitted to the fourth transmission shaft 15 after being shifted in three stages of high, medium and low, and this power is transmitted from the medium speed gear 18 to the first transmission gear 20. Be transmitted to.

A support shaft 25 for supporting the first transmission gear 20.
Further, the right and left side gears 26 are externally fitted so as to be rotatable relative to each other, and the input gears 28 of the left and right crawler type traveling devices 27 are always meshed with the left and right side gears 26. As a result, a pair of left and right side clutches 21 is formed between the left and right side gears 26 and the first transmission gear 20.
When it is occluded to 0, the power for straight traveling is transmitted to the left and right crawler type traveling devices 27, and the machine body goes straight. Also, spring 2
9 is for urging the side gear 26 toward the first transmission gear 20 side.

(2) In this combine, the slow-moving structure for driving the one traveling device 27 in the forward direction at a lower speed than the other traveling device 27 to gently swivel the vehicle body, and the one traveling device 2
7 has a super-spot turning structure for driving the airframe 7 in the reverse direction to turn the vehicle in the super-spot turning. Next, the gentle turning structure and the super-spinning turning structure will be described.

As shown in FIG. 4, a pair of second transmission gears 30 are externally fitted to the left and right of the support shaft 25, and a multi-plate friction clutch 31 is provided between the left and right second transmission gears 30 and the side gears 26.
Is provided. The turning gear 22 fixed to both ends of the fifth transmission shaft 32 meshes with the left and right second transmission gears 30, and the shift gear 23 is slidably fitted onto the fifth transmission shaft 32 by a spline structure. The slowly turning gear 39, which is fitted onto the fifth transmission shaft 32 so as to be relatively rotatable, meshes with the output gear 20 a fixed to the first transmission gear 20.

With the above structure, when the shift gear 23 is slid rightward on the paper surface to be engaged with the gentle turning gear 39, the forward drive power for straight traveling transmitted to the first transmission gear 20 is slowly transmitted to the output gear 20a. Revolving gear 39, shift gear 23
Also, it is converted into low-speed forward rotation power via the left and right turning gears 22 and transmitted to the left and right second transmission gears 30. In this state, for example, when the left side gear 26 is operated away from the first transmission gear 20 and the friction clutch 31 is pressed in and out by the pressing portion 43 of the left side gear 26, the low speed forward rotation of the second left transmission gear 30 is performed. The power is transmitted to the left traveling device 27. In this case, the right side gear 26 is the first transmission gear 20.
Since the right traveling device 27 is driven to rotate forward at a predetermined speed by engaging with, the machine body slowly turns to the left due to the difference in the driving speeds of the left and right traveling devices 27.

The reverse gear 24 is fitted onto the fifth transmission shaft 32 so as to be relatively rotatable, and the output gear 45 of the fourth transmission shaft 15 is provided.
The reverse rotation gear 24 is engaged with. With the above structure, the shift gear 23 is slid to the left side of the drawing to rotate the reverse gear 2
When the fourth transmission shaft 15 is engaged, the forward drive power for straight traveling of the fourth transmission shaft 15 is converted into the reverse drive power via the output gear 45, the reverse rotation gear 24, the shift gear 23, and the left and right turning gears 22, and the second left and right transmissions are transmitted. It is transmitted to the gear 30. In this state, for example, the left side gear 26 is operated to be separated from the first transmission gear 20, and the pressing portion 43 of the left side gear 26 causes the friction clutch 3 to move.
When 1 is pressed and operated, the reverse rotation power of the left second transmission gear 30 is transmitted to the left traveling device 27. In this case, the right side gear 26 is engaged with the first transmission gear 20 and the right traveling device 27 is normally driven at a predetermined speed, so that the aircraft makes a super turning turn to the left.

(3) Next, the sliding operation system of the left and right side gears 26 and the structure of the turning operation will be described. As shown in FIG. 3, the hydraulic oil from the pump 34 is passed through the switching valve 35 to the hydraulic cylinder 3 for the left and right side gears 26.
3, the side gear 26 is supplied to the first transmission gear 2
When the hydraulic cylinder 33 extends until it moves away from 0 and moves to a neutral stop position where the friction clutch 31 is not pressed and operated, a drain oil passage for draining hydraulic oil from the hydraulic cylinder 33 and stopping the hydraulic cylinder 33 at the neutral stop position 36
The drain oil passage 36 is provided with a variable relief valve 37.
Is provided. An operating lever 40 is supported by the control section of the machine body so as to be swingable left and right, and the operating lever 40, the switching valve 35, and the variable relief valve 37 are mechanically linked by linking mechanisms 41 and 42.

With the above structure, the shift gear 23 shown in FIG.
Is engaged with the slow turning gear 39 to select the slow turning state. When the operation lever 40 is operated to the neutral position N in this gentle turning state, the switching valve 35 is also operated to the neutral position, the left and right hydraulic cylinders 33 contract, and the left and right side gears 26 engage with the first transmission gear 20. To do. This makes the first
The forward rotation power transmitted to the transmission gear 20 is transmitted to the left and right traveling devices 27, the left and right traveling devices 27 are driven at the same speed, and the machine body moves straight.

Next, when the operating lever 40 is operated from the neutral position N to the first operating position R1 on the right side or the first operating position L1 on the left side, only the switching valve 35 is switched and the hydraulic cylinder 3 is operated.
3, the right or left side gear 26, which is in mesh with the first transmission gear 20, is separated from the first transmission gear 20 via the right or left operation portion 38. In this case, the variable relief valve 37
Is still fully open, the drain oil passage 36 is opened at the neutral stop position before the right or left side gear 26 presses the friction clutch 31, and the hydraulic oil escapes from the variable relief valve 37. Stops at the neutral stop position (transmission cutoff state of the side clutch 21). As a result, the transmission to the right or left traveling device 27 is cut off, and the machine body gradually turns to the right or left.

Next, the operating lever 40 is moved from the right or left first operating position R1, L1 to the right or left second operating position R2, L.
When it is operated to 2, the variable relief valve 37 is gradually throttled while the switching valve 35 is switched, the hydraulic cylinder 33 extends from the neutral stop position described above, and the side gear 26 is operated to the right or left. The friction clutch 31 is pressed and operated. In this case, since the shift gear 23 meshes with the gentle turning gear 39 and the low-speed forward rotation power is transmitted to the left and right second transmission gears 30, as described above, the side gear 26 presses one of the friction clutches 31 to perform an operation of pressing. Then, the right or left traveling device 27 is driven to rotate in the normal direction at a low speed, and the machine body slowly turns to the right or left. When the operating lever 40 is operated between the first operating position R1, L1 and the second operating position R2, L2, the hydraulic oil is drained from the hydraulic cylinder 33 from the above-mentioned state, and the pressing force on the friction clutch 31 is weakened. To be As a result, the friction clutch 31 slips and the low forward speed of the right or left traveling device 27 can be changed.

(4) Next, it is assumed that the shift gear 23 of FIG. 4 is engaged with the reverse rotation gear 24 to select the super-spinning state. When the operation lever 40 is operated to the neutral position N in this super-spinning state, the switching valve 35 is also operated to the neutral position as in the slow turning state described above, and the left and right side gears 26 are moved.
Engages with the first transmission gear 20 and the aircraft advances straight. When the operating lever 40 is operated from the neutral position N to the first operating position R1 on the right or the first operating position L1 on the left, only the switching valve 35 is switched and the side gear 26 is moved to the neutral stop position (side) as described above. The clutch 21 is stopped in the transmission cut-off state), the transmission to the right or left traveling device 27 is discontinued, and the aircraft gradually turns to the right or left.

Next, the operation lever 40 is moved from the right or left first operation position R1, L1 to the right or left second operation position R2, L.
When it is operated to 2, the variable relief valve 37 is gradually throttled while the switching valve 35 is being switched, the hydraulic cylinder 33 is extended from the neutral stop position, and the side gear 26 is operated to the right or left. The friction clutch 31 is pressed and operated. In this case, since the shift gear 23 is engaged with the reverse rotation gear 24 and the reverse rotation power is transmitted to the left and right second transmission gears 30, when the one side friction clutch 31 is pressed and operated by the side gear 26 as described above, the right or left The left traveling device 27 is driven in the reverse direction, and the airframe makes a super turning turn to the right or left. Then, the first operation positions R1, L
When the operation lever 40 is operated between the first operation position R2 and the second operation position R2, L2, the hydraulic oil is released from the above-mentioned state.
It is further pulled out, and the pressing force on the friction clutch 31 is weakened. As a result, the friction clutch 31 slips and the reverse rotation speed of the right or left traveling device 27 can be changed.

(5) Next, the switching operation structure of the shift gear 10 of the forward / reverse switching device 44 of FIG. 4 will be described. Figure 1
As shown in (a) and FIG. 2, the balance arm 46 (operating portion) that slides the shift gear 10 (see FIG. 4) of the forward / reverse switching device 44 over the interlocking positions of the forward gear 8 and the reverse gear 9. (Corresponding to a switching operation tool) is supported swingably around the horizontal axis P1 on the front surface of the mission case 1 and is provided in the control section of the aircraft (corresponding to a switching operation tool).
And one end of the balance arm 46 are interlockingly connected by a connecting rod 48.

As a result, the switching lever 47 is moved to the forward position F.
4 is operated by the balance arm 46, the shift gear 10 of FIG. 4 is slid and engaged with the forward drive gear 8, and forward forward power is transmitted to the lower side, and the switching lever 47 is operated to the reverse drive position R. Then, the shift arm 10 is slid in the opposite direction by the balance arm 46 to be engaged with the reverse gear 9, and the reverse power for reverse is transmitted to the lower side.

As shown in FIGS. 1 (a) and 2, a support bracket 49 bent in an L-shape in plan view is swingably supported around a horizontal axis P2 on the front surface of the mission case 1, and a balance arm is provided. A rod 50, which is swingably supported around the first pin 46a at the other end of 46, is slidably inserted into a support bracket 49 in the left-right direction of the drawing, and a spring 51 that biases the rod 50 to the left of the drawing. Is attached. With the above structure, the balance arm 46 and the switching lever 47 are held at the forward drive position F and the reverse drive position R by the biasing force of the spring 51.

(6) Next, a temporary stop structure for traveling in this combine will be described. As shown in FIGS. 1A and 2, a pair of upper and lower operation arms 53 (corresponding to a stop operation mechanism) are swingable around a horizontal axis P3 of a bracket 52 connected to the front surface of the mission case 1. A spring 54 that is supported and that urges both operation arms 53 in a direction away from each other is attached. A stop pedal 55 (corresponding to a stop operation tool) is provided in the control section of the machine body.
The inner wire 56a of the release wire 56 is connected across the one operation arm 53 and the stop pedal 55,
The outer 56b of the release wire 56 is connected to the other operation arm 53.

With the above structure, when the stop pedal 55 is stepped on during the forward movement by operating the switching lever 47 to the forward drive position F as shown in FIG. In (a), the operation arm 53 on the lower side of the paper is rocked upward on the paper, and the operation arm 53 on the upper side of the paper is rocked on the lower side of the paper. This allows
The pair of operation arms 53 is the first pin 46 of the balance arm 46.
Since the balance arm 46 in the forward movement position F is forcibly operated and held at the neutral stop position N as shown in FIG. 1B by sandwiching the a and the second pin 46b, accordingly. The switching lever 47 is also forcibly operated and held at the neutral stop position N.

At the neutral stop position N of the switching lever 47 and the balance arm 46, as shown in FIG. 4, the shift gear 10 of the forward / reverse switching device 44 is set to the neutral stop position in which the forward gear 8 and the reverse gear 9 are not engaged. Since the operation is performed, the power is shut off in the forward / reverse switching device 44 and the machine body is stopped. In this stopped state of the machine, as shown in FIG. 4, the power from the engine is input to the continuously variable transmission 2 from the input pulley 3, and the power from the continuously variable transmission 2 is transmitted to the forward / reverse switching device 44 side. Therefore, the gear shifting operation of the continuously variable transmission 2 can be performed without any trouble even when the machine body is stopped.

[Other Embodiments] In the configuration shown in FIGS. 1A and 1B, the operation arm 53 may be configured to directly act on the switching lever 47 instead of acting on the balance arm 46. Further, instead of the belt type continuously variable transmission 2, the continuously variable transmission 2 using a tapered cone may be used.

Instead of the forward / reverse switching device 44 using the shift gear 10 as shown in FIG. 4, a hydraulic system in which a pair of hydraulic clutches (not shown) and a switching valve for hydraulic clutches (not shown) are combined, The forward / reverse switching device 44 may be configured. When the forward / reverse switching device 44 is configured hydraulically, the switching valve or the switching can be changed by mechanically linking the switching valve for the hydraulic clutch and the switching lever (or the switching pedal (corresponding to the switching operation tool)). The lever (switching pedal) is configured to be returned to the neutral stop position and operated. When the changeover valve and the changeover switch (corresponding to a changeover operation tool) are electrically linked, the changeover switch is returned to the neutral stop position.

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

[Brief description of drawings]

FIG. 1 is a front view of the vicinity of a balance arm and an operation arm of a forward / rearward travel switching device, showing a state before and after a stop pedal is depressed.

FIG. 2 is a plan view of the vicinity of the balance arm and the operation arm of the forward / reverse switching device.

FIG. 3 is a hydraulic cylinder for left and right side gears, a switching valve,
The figure which shows the hydraulic circuit of a variable relief valve and an operating lever, and a connection state.

FIG. 4 is a schematic diagram showing a transmission structure in a mission case.

[Explanation of symbols]

 2 continuously variable transmission 27 traveling device 44 forward / reverse switching device 46 operation unit 47 switching operation tool 53 stop operating mechanism 55 stop operation tool N neutral stop position of forward / reverse switching device F forward position of forward / reverse switching device R forward / reverse switching device Reverse position

Claims (1)

[Claims] 1. The power of an engine is transmitted from a continuously variable transmission (2) to a traveling device (27) through a lower side forward / reverse switching device (44). 44) for operation of switching (4)
6) and a switching operation tool (47) that is manually operated, and the switching operation tool (47) causes the forward / reverse switching device (44) to move to the forward drive position (F) and the reverse drive position (R). It is configured to be freely switchable, and the stop operation tool (5
5), and in conjunction with the operation of the stop operation tool (55) to the stop operation side, the switching operation tool (N) is moved to the neutral stop position (N) where the forward / reverse switching device (44) does not transmit power. Four
7) A traveling power transmission structure for a work vehicle, which is provided with a stop operation mechanism (53) for operating.