JPH06191300A - Transmission structure for agricultural work vehicle - Google Patents

Abstract

PURPOSE:To provide a motive power taking-out transmission structure having excellent operability and safety in a simple structure. CONSTITUTION:In a transmission structure for an agricultural work vehicle, a transmission system is constituted so that motive power from an engine can be supplied to a motive power taking-out shaft through a friction type hydraulic clutch 14 which is energized to the clutch releasing side and on which clutch throwing-in operation is carried out by supplying operating oil, and a gear shift type speed changing mechanism is provided on the downstream side of transmission of the hydraulic clutch 14. The transmission structure has a brake mechanism B constituted in such a way that when a hydraulic piston 28 in the hydraulic clutch 14 is returned/operated to a clutch releasing position, a braking operation part 39 interlocking with it is brought into pressure contact with a fixed side braking member 40 by clutch releasing energizing force, and braking is applied, and the fixed side braking member 40 is supported with a transmission case side fixing pin 41 so as to be capable of making relative rotation freely within a prescribed small range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies power from an engine to a power take-off shaft through a friction hydraulic clutch that is biased to the clutch disengagement side and is operated by a hydraulic oil supply. The present invention relates to a transmission structure of an agricultural work vehicle that constitutes a transmission system and includes a gear shift type transmission mechanism on the transmission lower side of the hydraulic clutch.

[0002]

2. Description of the Related Art In the transmission structure for an agricultural work vehicle, in the related art, for example, when an external work device such as a lawn mowing work device is used and driven by a power takeoff shaft, the driven side is Since it is dangerous because the driving inertia force of the lawnmower work machine may continue the rotating state, in order to surely stop the rotation of the power take-off shaft during such a clutch disengagement operation, the clutch disengagement side of the hydraulic clutch is moved to the disengagement side. A structure in which a frictional brake mechanism for braking the driven side is provided by utilizing the spring force of the urging spring is considered.

[0003]

However, in the above-mentioned conventional structure, since the transmission mechanism of the hydraulic clutch is provided on the lower transmission side, when the driven side of the hydraulic clutch is braked, the transmission mechanism of the transmission mechanism is changed. There is a risk that the gears will hit each other and will not bite, and the shift operation cannot be performed smoothly. Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 4-113935, a hydraulic braking mechanism having a structure different from that of the hydraulic clutch is provided so that a state in which the clutch is disengaged and the braking action is not exerted can be realized. What made up was considered. However, if this improved structure is applied to the above transmission system, a braking member, a braking hydraulic cylinder, hydraulic piping, and the like are required in addition to the hydraulic clutch, and the structure becomes complicated and the cost becomes high. The present invention eliminates the above-mentioned inconveniences and, by a simple structure, can prevent the power take-off shaft from rotating due to inertia during clutch disengagement operation, and also provides a transmission mechanism located on the lower transmission side during clutch disengagement operation. The purpose is to be able to change gears.

[0004]

In the transmission structure of an agricultural work vehicle described at the beginning, the characteristic structure of the present invention is that when the hydraulic piston in the friction hydraulic clutch is operated to return to the clutch disengaged position, it interlocks with the hydraulic piston. The braking action part includes a brake mechanism for pressing the fixed side braking member by a clutch disengagement urging force to brake the fixed side braking member, and the fixed side braking member is rotatably supported within a predetermined small range with respect to the transmission case side fixing member. There is a point.

[0005]

When the supply of pressure oil to the hydraulic clutch is stopped and the clutch is disengaged, the hydraulic piston is returned to the clutch disengaged position by the clutch disengagement urging force, and the braking action portion interlocked with the hydraulic piston is pressed against the fixed side braking member. The brake is applied to the driven side. As a result, rotation of the power takeoff shaft due to inertial force is prevented. Then, when the gear shift type transmission mechanism located on the lower transmission side is operated to shift while the clutch is disengaged in this way, even if the gears come into abutting contact with each other at the edges, the lower transmission side of the hydraulic clutch is Since the transmission shaft can rotate relative to the transmission case within a predetermined small range, the gears can be engaged with each other by a slight shift in the rotational phase, and a gear shift operation for shifting can be performed.

[0006]

Therefore, the clutch disengagement force of the hydraulic piston in the hydraulic clutch can be effectively utilized to obtain the braking function of the power take-out shaft, and the fixed side braking member required in the braking mechanism can be simply improved. As a result, even when the clutch is disengaged, it is possible to perform a gear shift operation of the transmission mechanism located on the lower transmission side, and it is possible to provide a transmission structure excellent in operability and safety with a simple structure.

[0007]

Embodiments will be described below with reference to the drawings. Figure 1
An agricultural tractor, which is an example of an agricultural vehicle, is shown in FIG. This agricultural tractor transmits the power of the engine 1 mounted on the front part of the machine body to the front and rear wheels 3 and 4 via the mission case 2, and the rear power take-off shaft 5 provided on the rear part of the machine body and the central power take-off provided on the lower part of the machine body. A transmission system is configured to supply power to the shaft 6. More specifically, as shown in FIG. 2, the power of the engine 1 is input to a gear shift type main transmission mechanism 9 via a main clutch 7 and a cylinder shaft 8, and its shift output is transmitted via a sub transmission mechanism 10 to a rear wheel difference. While being supplied to the dynamic mechanism 11, the airframe traveling drive system is configured such that the dynamics mechanism 11 supplies the front wheels 3 via the front wheel speed increasing mechanism 12. Further, the input shaft 13 to which the power of the engine 1 is directly supplied is fitted in the cylindrical shaft 8 in a free-rotating manner, and the power take-off shafts 5 and 5 are provided through a hydraulic PTO clutch 14 and a gear shift operation type PTO transmission mechanism 15. The PTO transmission system is configured so that power is supplied to 6.

Next, the mounting structure of the PTO clutch 14 will be described. The PTO clutch 14 is composed of a multi-plate friction type hydraulic clutch, and is configured so that it can be mounted in the mission case 2 in an assembled state assembled in advance in a unitized state.
A large opening 22 formed on the upper side of the mission case 2
It can be installed from the upper side through. That is,
As shown in FIG. 3, the driven side friction plate 23 is integrally rotatably engaged, and the driven member 25 spline-fitted to the driven shaft 24 is supported by the bearing 26 via the bearing 26.
It is supported in a unit state in such a manner that it is rotatably fitted inside by means of 7. Further, the hydraulic piston 28 is slidably fitted in the cylindrical space formed by the drum portion 25a and the spline boss portion 25b of the driven member 25, and the inside formed by piercing the support case 27 and the driven member 25. Oil passage L1,
The hydraulic oil is supplied to the oil chamber R of the hydraulic piston 28 via L2. The hydraulic piston 28 is configured to be biased toward the clutch disengagement side by a compression spring 30 that is interposed between the hydraulic piston 28 and a bearing 29 that is externally fitted and fixed to the spline boss portion 25b. The unitized PTO clutch unit is inserted from the upper side through the opening 22 formed in the upper portion of the transmission case 2 from above and, as shown in FIGS. 27a, 27a through the opening 2
In FIG. 2, the left and right side wall portions 31, 31 are erected, connected, and fixed over a stepped portion in the middle. Then, after the clutch unit is mounted, the opening 22 of the mission case 2 is covered with the cover 32.
It is configured to be closed by.

The hydraulic oil for the PTO clutch 14 is configured so that the return oil of the hydraulic circuit for power steering is supplied, and the switching control valve 33 is directly bolted to a mounting seat 34 formed on the side of the transmission case 2. The oil passage between the control valve 33 and the oil chamber R is an internal oil passage L3 bored in the mission case 2 and the internal oil passages L1 and L of the support case 27 and the driven member 25.
2 and these oil passages are connected to the mission case 2
The hydraulic pressure control valve 33 is attached and fixed to the support case 27, and the hydraulic control valve 33 is attached and fixed to the transmission case 2, so that the communication connection is made as it is, and hydraulic piping is omitted to simplify the structure. , The workability of assembly is improved.

As shown in FIG. 3, the hydraulic piston 28 of the PTO clutch 14 is operated at a position where the drive-side friction plate 35 faces the friction plate engagement portion of the inner engagement member 36 with which the spline is externally engaged. By forming a small-diameter through hole 37 connected to the hydraulic pressure chamber R so that the oil can be smoothly supplied to the spline engaging portion, the movement of the friction plate 35 in the axial direction during the clutch disengagement operation is facilitated. The clutch disengagement operation can be reliably performed. Although a part of the operating oil pressure is lost when the clutch is engaged, it has a small diameter and cannot be operated. Further, when the hydraulic piston 28 is slid to the clutch disengagement side by the spring 30, the brake mechanism B exerts a braking action on the driven side.
Is equipped with. That is, the plurality of pins 38 that are driven and fixed to the hydraulic piston 28 are connected to the drum portion 25 of the driven member 25.
a is slidably inserted, and a ring-shaped braking sliding contact member 39 (an example of a braking action portion) is screwed to the pin 38 on the outer side of the drum portion 25a.
A ring-shaped fixed-side braking member 40 received and supported by the support case 27 is provided at a position where the sliding contact member 39 faces. As shown in FIG. 7, the fixed-side braking member 40 has the support pin 4 fixed to the support case 27 by driving.
1 (an example of a mission case side fixing member) is engaged,
The support pin 41 is configured so as to be prevented from rotating.
The engaging recess 42 with which is engaged is configured to allow relative rotation by a predetermined angle [about 60 degrees]. With this configuration, even in the clutch disengaged state, the switching operation of the PTO transmission mechanism 15 provided on the transmission lower side of the clutch can be performed.

Support case 27 for the clutch unit
Is used as a material even in a model in which the PTO clutch 14 is not mounted. That is, when the PTO clutch 14 is not mounted, the bearing 43 is simply supported as shown in FIG. 4, and when the PTO clutch 14 is mounted, the driven member 25 is fitted in the material from this material. The parts and the mounting parts of the brake mechanism B are machined to correspond.

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

[Brief description of drawings]

1] Overall side view of an agricultural tractor

[Fig. 2] Transmission system diagram

FIG. 3 is a sectional view of the PTO clutch with the clutch engaged.

FIG. 4 is a sectional view when the PTO clutch is not attached.

FIG. 5 is a sectional view of the PTO clutch with the clutch engaged.

FIG. 6 is a plan view showing a mounted state of a PTO clutch unit.

FIG. 7 is a front view showing a mounted state of the PTO clutch unit.

[Explanation of symbols]

 1 Engine 5,6 Power Extraction Shaft 14 Hydraulic Clutch 15 Transmission Mechanism 28 Hydraulic Piston 39 Braking Action Section 40 Fixed Side Braking Member 41 Mission Case Side Fixed Member B Brake Mechanism

Claims (1)

[Claims] 1. A power take-off shaft (5) via a friction hydraulic clutch (14) which is urged by a clutch disengagement side to motive power from an engine (1) and which is operated by supplying hydraulic oil to engage the clutch. (6) A transmission system is configured to supply the hydraulic clutch (14) and a transmission structure of an agricultural work vehicle is provided with a gear shift type transmission mechanism (15) on the transmission lower side of the hydraulic clutch (14), wherein the friction hydraulic clutch ( When the hydraulic piston (28) in (14) is operated to return to the clutch disengaged position, the braking action portion (3) interlocked with the hydraulic piston (28).
9) causes the stationary side braking member (4
0) is provided with a brake mechanism (B) for braking by pressing, and the fixed side braking member (40) is rotatably supported within a predetermined small range with respect to the mission case side fixing member (41). Transmission structure of agricultural work vehicle.