JPH09123776A - Power transmission of work wagon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the operating failure of an interlocking mechanism caused by sticking of the rust of a linking mechanism arranged in an external side or foreign objects in a structure in which the traveling speed changing lever or a multistage transmission and the operation lever of a mechanical clutch are interlocked with each other in the linking mechanism provided in the external part of a transmission case. SOLUTION: In the power transmission of a work wagon having a transmission having forward, neutral and backward positions and a mechanical clutch freely engaged/disengaged, the shift fork 11 of the mechanical clutch is arranged with play on a rotary shaft 46 rotated associatively with the speed changing operation of the transmission. Further, a thrust adding mechanism for moving the shift fork 11 to a clutch switching OFF position when the transmission is operated to at least one of the neutral position and the backward position is provided between the rotary shaft 46 and the shift fork 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission for a work vehicle equipped with a transmission for shifting power from an engine and transmitting the power to a traveling portion, and a mechanical clutch for connecting / disconnecting power to / from the working portion. Regarding a transmission device.

[0002]

2. Description of the Related Art Conventionally, regarding a power transmission device for a work vehicle equipped with a transmission and a mechanical clutch, a technique for interlocking the mechanical clutch so as to disengage it at a predetermined gear position of a multi-stage transmission is the same applicant. Japanese Patent Application No. 6-207185
Techniques such as those in Japanese Patent Publication have been proposed.

[0003]

However, in the prior art, since the traveling speed change lever of the transmission and the operation lever of the mechanical clutch are interlocked with each other by the link mechanism provided outside the mission case, the external mechanism is used. The rusting of the link mechanism arranged in the above and the adhesion of foreign matter occurred, which caused a malfunction of the interlocking mechanism. The present invention solves the problem by configuring the interlocking mechanism so that it can be arranged inside the mission case.

[0004]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. The transmission is provided with a forward position, a neutral position, and a reverse position for shifting the power from the engine and transmitting the power to the traveling unit, and a mechanical clutch that can be engaged and disengaged between the engine and the working unit. In a power transmission device for a work vehicle, a shift fork of a mechanical clutch is loosely fitted on a rotary shaft that rotates in conjunction with a shift change operation of a transmission, and a gear shift is performed between the rotary shaft and the shift fork. A thrust applying mechanism is provided for moving the shift fork to the clutch disengagement position when the device is operated in at least one of the neutral position and the reverse position.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a skeleton diagram of a power transmission device for a work vehicle, FIG. 2 is a sectional view showing a speed change mechanism and a clutch mechanism of a portion of an input shaft 2 and a power takeoff shaft 20, and FIG. 3 is a speed change shift fork shaft 43 and a rotary shaft 46. FIG. 4 is a developed sectional view showing the relationship of the speed change operation valve V, and FIG.
5 is a perspective view of the cam groove 12 formed on the end surface of the boss portion 11a of the shift fork 11, and FIG. 6 is a hydraulic circuit diagram of a hydraulic clutch including the shift operation valve V.

A power transmission device for a work vehicle will be described with reference to FIG. The driving force from the engine is input to the input pulley 2a of the input shaft 2 via the V belt. The rotation input to the input pulley 2a is changed in speed to change the power output shaft 20.
And output to the traveling output shafts 31L and 31R. First, the speed change mechanism from the input pulley 2a to the output pulley 20a of the power takeoff shaft 20 will be described.

The input pulley 2a is fixed to the portion where the input shaft 2 is projected to the outside of the mission case 1. Power is input to the input pulley 2a by the V belt.
On the input shaft 2 in the mission case 1, a sub-transmission slide body 3 is spline-engaged so as to be relatively non-rotatable and slidable in the axial direction. Further, the gear 4 is loosely fitted and installed. The sub-transmission slide body 3 includes a gear portion 3b and a gear portion 3b.
It is configured as a double gear consisting of a. The gear portion 3b
Can mesh with a fixed gear 9 on the counter shaft 6 which is erected on the lower side of the power transmission system. Also, the gear unit 3
The a can mesh with the fixed gear 8 on the counter shaft 6.
Further, the gear portion 3a can be engaged with the internal tooth portion of the gear 4 on the input shaft 2. Further, the gear 4 is always the counter shaft 6
It meshes with the upper fixed gear 7.

By slidingly operating the auxiliary transmission sliding body 3 by an auxiliary transmission shifter (not shown), high, medium, and low three-stage auxiliary transmission rotations can be obtained on the counter shaft 6. That is, when the gear portion 3b meshes with the fixed gear 9, the auxiliary shift speed becomes low, and when the gear portion 3a meshes with the fixed gear 8, the auxiliary gear shifts to the middle speed, and the gear portion 3a becomes the inner tooth portion of the gear 4. By engaging with, the auxiliary shift speed is increased.

Two hydraulic clutch shafts 71 and 22 are installed on the lower side of the power transmission system of the counter shaft 6. On the hydraulic clutch shaft 71, the hydraulic clutch F1
F3 is installed, and the hydraulic clutch F2.R is installed on the hydraulic clutch shaft 22. In addition, the fixed gear 10 on the counter shaft 6 is loosely fitted on the hydraulic clutch shaft 71, and the hydraulic clutch F1 causes the hydraulic clutch shaft 71 to move.
It always meshes with the forward first-stage gear 25 that is engaged and disengaged with the. Further, the forward first-stage gear 25 on the hydraulic clutch shaft 71 is loosely fitted on the hydraulic clutch shaft 22 and always meshes with the reverse gear 26 that is engaged with and disengaged from the hydraulic clutch shaft 22 by the hydraulic clutch R.

Further, the fixed gear 9 on the counter shaft 6 is
The hydraulic clutch F3 is loosely fitted on the hydraulic clutch shaft 71,
3rd forward gear 7 disengaged from the hydraulic clutch shaft 71 by
Always meshes with 3. Further, the fixed gear 9 is loosely fitted on the hydraulic clutch shaft 22 and always meshes with the forward two-stage gear 24 that is engaged with and disengaged from the hydraulic clutch shaft 22 by the hydraulic clutch F2. As described above, the hydraulic clutch type main transmission device is configured, and the rotation of the counter shaft 6 is always transmitted to the first forward gear 25, the second forward gear 24, the third forward gear 73, and the reverse gear 26. The hydraulic clutches F1, F2, F3 are switched by switching the speed change operation valve V.
-By selectively operating one of the Rs to the connected state, a main shift of three forward gears and one reverse gear can be obtained.

Further, a power transmission gear 27 is fixed to the center of the hydraulic clutch shaft 71, and a power transmission gear 28 is fixed to the center of the hydraulic clutch shaft 22. Power transmission gear 2
7 and the power transmission gear 28 are simultaneously meshed with a large-diameter gear 30 installed on the steering shaft 29 to transmit the power via the main transmission device to the steering shaft 29. A parking brake 32 is arranged at a portion where the hydraulic clutch shaft 22 projects to the left side surface of the transmission case 1. Also, to the left and right of the steering shaft 29,
Left and right steering hydraulic brakes 28L and 28R and steering clutch gears 33L and 33R are provided. By supplying pressure oil to an actuator (not shown), one of the steering clutch gears 33L and 33R slides outward and is formed on both side surfaces of the steering clutch gears 33L and 33R and the large diameter gear 30. The engaged state with the inner teeth 30L and 30R is released, the steering clutch is disengaged, and the body gently turns. When pressure oil is further supplied to the actuator, the steering clutch gears 33L and 33R press the friction plates of the steering hydraulic brakes 28L and 28R to brake the steering clutch gears 33L and 33R. As a result, the aircraft makes a sharp turn.

Although the steering clutch gears 33L and 33R are slidable, the steering clutch gears 33L and 33R are wide so as to maintain a constant meshing state with the fixed gears 34L and 34R on the traveling output shafts 31L and 31R. From the output shafts 31L and 31R,
The drive sprockets 35L and 35R are driven. The drive sprockets 35L and 35R drive the left and right crawler type traveling devices (not shown) which are traveling parts. Further, a hydraulic pump P for supplying pressure oil to the hydraulic clutch type main transmission is arranged at a portion of the input shaft 2 on the opposite side of the input pulley 2a and protruding from the transmission case 1 to drive the hydraulic clutch type main transmission. Has been done.

The above is a description of a traveling transmission including a gear sliding type sub transmission, a hydraulic clutch type main transmission, and a hydraulically operated steering device. Next, a power take-out mechanism that branches from the input shaft 2 and drives the power take-out shaft 20 will be described. A cylindrical shaft 19 is loosely fitted and installed on the power output shaft 20. Gear 16 engraved on counter shaft 15
Is formed wide so that the gear portion 3a always maintains the meshed state regardless of the sliding position of the auxiliary transmission sliding body 3 to the left and right. The gear 16 meshes with a large-diameter gear 21 which is loosely fitted and arranged on the cylinder shaft 19. Also, the counter shaft 15
The gear 17 fixed above is meshed with a small diameter gear 42 which is loosely fitted on the power take-off shaft 20.

A shift slider 23 is provided on the cylinder shaft 19.
The splines are engaged so that they cannot rotate relative to each other and are slidable in the axial direction. When the engaging portion 23a formed on one side surface of the speed change slider 23 meshes with the engaging protrusion 21a of the large-diameter gear 21, the cylinder shaft 19 rotates at a low speed. Reverse gear slider 2
The engagement portion 23b formed on the other side surface of the third gear meshes with the engagement protrusion 42a of the small-diameter gear 42, so that the cylinder shaft 19 can rotate at high speed. The transmission slider 23 and the large diameter gear 21
Moreover, it is also possible to switch to a neutral position in which the small diameter gear 42 is not engaged.

A clutch mechanism for engaging and disengaging the power take-off shaft 20 and the cylinder shaft 19 cannot rotate relative to the engaging body 44 fixed to the end of the cylinder shaft 19 and the power take-off shaft 20,
In addition, the clutch slider 14 is slidable in the axial direction. The claw portion 14a formed on the side surface of the clutch slider 14 meshes with the protrusion 44a of the engaging body 44 so that the rotation of the cylindrical shaft 19 is transmitted to the power take-off shaft 20. Reference numeral 37 is an urging spring that urges the clutch slider 14 toward the clutch engagement side.

As shown in FIG. 3, the shift slider 23 is engaged with a shifter 41 which slides on the shift shift fork shaft 43 axially rightward. The shifter 41 mounts the transmission shaft 45 protruding outside the mission case 1 on the arm 48.
The rotation of the arm 5 causes the arm 5 fixed to the end of the transmission shaft 45 protruding inside the mission case 1.
It is slid to the left and right on the shift shift fork shaft 43 via 1 and the pin 52.

In the above general construction, the present invention provides
The shift fork 11 for operating the engagement / disengagement of the clutch of the clutch slider 14 and the traveling speed change lever 36 for operating the speed changeover valve V are interlocked, and a thrust applying mechanism for the shift fork 11 is provided at this portion. is there. That is, when the multi-stage transmission constituted by the hydraulic clutch type transmission is in reverse and in neutral, the clutch slider 14 is automatically moved to the clutch disengagement side so as not to transmit power to the working part. It is a move.

When the rotary shaft 46 fixed to the base end side of the traveling speed change lever 36 is rotated by the swinging operation of the lever 36, the spool operation arm 47 fixed to the rotary shaft 46 shifts through the pin 49. The spool 50 of the operation valve V is configured to slide in the axial direction. The spool 50
By properly selecting the sliding position of, it is possible to obtain a neutral position with three forward gears and one reverse gear. Next, a thrust applying mechanism that constitutes a main part of the present invention will be described.
A shift fork 11, which is an essential part of the present invention, is slidably mounted on the outer periphery of the rotary shaft 46, and a cam groove 12 is formed on one side surface of a boss 11a of the shift fork 11. .

Cam pins 38 projecting from the outer peripheral surface of the rotary shaft 46 in opposite directions are engaged with the cam grooves 12. As shown in FIG. 5, the cam groove 12 has a cam pin 38.
However, among the 5 positions of 3 forward gears, 1 reverse gear, and neutral that are displaced by the rotation of the rotary shaft 46, the portion corresponding to the neutral position and reverse gear is shallow, and corresponds to the 1st forward gear to 3rd gear position. The shape is such that the portion to be deepened is deep (the displacement of the cam pin 38 is shown by the chain double-dashed line in FIG. 5). With this configuration, when the rotary shaft 46 is rotationally operated to the neutral position or the reverse position by the traveling speed change lever 36, the cam pin 38 rides on the shallow portion of the cam groove 12, and the shift fork 11 has the left side of FIG. A thrust force is applied in the direction of the arrow and slides on the rotary shaft 46 against the biasing spring 37. That is, the cam pin 38 of the rotary shaft 46 and the shift fork 1
The first cam groove 12 constitutes a thrust applying mechanism for urging the shift fork 11 toward the clutch disengagement side. By sliding the shift fork 11 to the left side of the drawing, the clutch slider 14 on the power takeoff shaft 20 slides toward the clutch disengagement side, and the rotation of the power takeoff shaft 20 is stopped.
As the transmission applied to the present invention, various continuously variable transmissions such as HST and stepped transmissions such as gear sliding type may be used in addition to the hydraulic clutch type transmission shown in the embodiment. .

[0020]

As described above, the present invention has the following advantages. First, when the multi-speed transmission is operated to at least one of the neutral position and the reverse position, the mechanical clutch is in the clutch disengaged state and the rotation of the working unit is automatically stopped. When not present, the working unit is not driven wastefully, waste of engine power can be suppressed, and operability can be improved.

Secondly, in the prior art, since the traveling speed change lever of the multi-speed transmission and the operation lever of the mechanical clutch are interlocked with each other by the link mechanism provided outside the mission case, they are arranged outside. The link mechanism suffered from rusting and adhesion of foreign matter, which caused a malfunction of the interlocking mechanism. According to the present invention, since the gear shift interlocking mechanism is arranged inside the mission case, the possibility of malfunction is extremely reduced, and the gear shift can be performed easily.

As shown in the embodiment, the thrust applying mechanism is constituted by the cam pin 38 protruding on the outer peripheral portion of the rotary shaft 46 and the cam groove 12 formed on one side surface of the boss portion 11a of the shift fork 11. Therefore, the rotary shaft 46 is
The shift fork 11 can also be used as a support shaft, the number of parts can be reduced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram of a power transmission device for a work vehicle.

FIG. 2 is a cross-sectional view showing a speed change mechanism and a clutch mechanism in a portion of an input shaft 2 and a power take-off shaft 20.

FIG. 3 is a developed cross-sectional view showing the relationship between a shift shift fork shaft 43, a rotary shaft 46, and a shift operation valve V.

FIG. 4 is a side sectional view of the same.

FIG. 5 is a perspective view of a cam groove 12 formed on an end surface of a boss portion 11a of the shift fork 11.

FIG. 6 is a hydraulic circuit diagram of a hydraulic clutch including a shift operation valve V.

[Explanation of symbols]

 P hydraulic pump V speed change operation valve 1 mission case 11 shift fork 12 cam groove 14 clutch slider 36 traveling speed change lever 38 cam pin 46 rotating shaft

Claims (1)

[Claims] 1. A transmission having a forward drive position, a neutral position, and a reverse drive position for speed-changing and transmitting power from an engine to a traveling unit, and a mechanical system capable of engaging and disengaging between the engine and the working unit. In a power transmission device for a work vehicle including a clutch, a shift fork of a mechanical clutch is loosely fitted on a rotary shaft that rotates in conjunction with a gear shift operation of a transmission, and the rotary shaft and the shift fork are provided. And a thrust applying mechanism for moving the shift fork to the clutch disengagement position when the transmission is operated to at least one of the neutral position and the reverse position. .