JPH02113167A - Transmission for running vehicle - Google Patents

Abstract

PURPOSE:To prevent engine start due to inertia by providing an electromagnetic throttling valve to regulate return oil from a hydraulic actuator at cutoff of an electric source, in an oil passage connecting a hydraulic actuator for clutch operation to an electromagnetic control valve. CONSTITUTION:Pressure oil from a hydraulic pump 13 is introduced to a hydraulic cylinder C5 for operating a main clutch through an electromagnetic control valve V5, and an electromagnetic throttling valve 15 is provided on an oil passage connecting the hydraulic cylinder C5 to the electromagnetic control valve V5. This electromagnetic throttling valve 15 let the total quantity of pressure oil pass through usually, but at OFF of the main key of a tractor, actuates so as to regulate return oil from the hydraulic cylinder C5. Consequently, at engine stop, clutch on due to drop of oil pressure is previously prevented, and start of the vehicle due to inertia of the engine is prevented. Thus the vehicle can be kept in stable condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulically operated automatic transmission provided in a traveling vehicle such as a tractor.

[Prior technology] Electronically controlled transmissions that use hydraulic actuators to automatically engage and disengage the main clutch, which intermittent power from the engine, and change gears, have been adopted in traveling vehicles such as tractors. has been done.

[Problems to be Solved by the Invention] In the conventional transmission described above, when the hydraulic pump is stopped by turning off the engine key, the hydraulic actuator for operating the main clutch becomes low pressure and the clutch is engaged, causing the vehicle body to shift due to the inertia of the engine. It was dangerous to move forward.

[Means for Solving the Problems] In order to solve the above problems, the present invention has the following configuration.

That is, the transmission device for a traveling vehicle according to the present invention is a transmission device for a traveling vehicle that automatically performs clutch engagement/disengagement operations and gear change operations using hydraulic pressure, and includes a hydraulic actuator for operating the clutch and its TL electromagnetic actuator. A feature is that a magnetic throttle valve 1a is provided in the oil path connecting the control valves to regulate the amount of oil returned from the hydraulic actuator when the power is turned off.

[Function] An electromagnetic throttle valve is installed in the oil path connecting the hydraulic actuator for clutch operation and its electromagnetic control valve, which regulates the amount of oil returned from the hydraulic actuator when the power is turned off. Even when the clutch is disengaged, the internal pressure of the hydraulic actuator does not drop suddenly.9 Since the clutch remains disengaged for a while, starting due to engine inertia is prevented.

[Embodiment] Fig. 1 is a power transmission system diagram of a tractor according to an embodiment of the present invention.
The transmission is transmitted to the driving system via the main and sub-transmission devices 4 and 5.
to drive the drive wheels 6, 6, and the PTO
The signal is transmitted to the working system via the clutch 8, and is then changed in speed by the PTO transmission 9 and transmitted to each driving section of the working section.

The main and auxiliary transmissions 4.5 are each capable of shifting into 4 speeds, and as operating means, the main transmission N4 uses a hydraulic cylinder C1,
C2 and its electromagnetic switching valves vt, V2, and the sub-transmission device 3 includes hydraulic cylinders C3, C4 and electromagnetic switching valves V3. It is equipped with V4. A clutch pedal 11 and a hydraulic cylinder C5 controlled by an electromagnetic control valve 5 are connected to the operating fork of the main clutch 2, and the clutch can be operated by either the pedal or the cylinder. On the other hand, P.T.O.
The clutch 8 is operated by a hydraulic cylinder C6 controlled by an electromagnetic control valve v6. Each of these cylinders C1 to C6 has a stroke sensor S1 for detecting its contracted state.
~S6 is installed. Further, rotation speed sensors R1, R2, and R3 are provided on the drive side and driven side of the clutch 2 and on the load side of the auxiliary transmission 5, respectively, for detecting the rotation speed of the shaft.

Figure 2 is a speed change operation circuit diagram of this hydraulic system, in which the pressure oil led from the hydraulic pump 13 is
．． V7, and from each valve hydraulic cylinder C5 for operating the main clutch and hydraulic cylinder C for operating the PTO clutch.
6, and hydraulic cylinder 01 for gear change operation
It is configured to be supplied to C4. Normally, the entire amount of pressure oil passes through the oil path connecting the hydraulic cylinder C5 for operating the main clutch and its electromagnetic control valve ■5, but when the main key 14 of the tractor is turned off, the hydraulic cylinder C
An electromagnetic throttle valve 15 is provided which switches to regulate the amount of oil returned from the oil pump 5 to a small amount. Hydraulic cylinder 01~C
The electromagnetic switching valves v1 to 4 are 3-position, 4-boat switching valves, and the switching valve V1 switches the main speed between 1st speed and 2nd speed.
Switching valve ■2 switches the main gear between 3rd speed and 4th speed.
3 switches the sub-shift between high speed and low speed, and switching valve v4 switches the sub-shift between reverse and medium speed.

FIG. 3 is a block diagram of the speed change control device 3120 provided in the control box 19, and the detection results of each stroke sensor 31 to S6 are sent to the C through the A/D converter 21.
The detection results of the rotation speed sensors R1 to R3 are input to the PU 22, and the detection results are directly input to the CPU 22. When a shift is set by the operation switch 24 of the main and auxiliary transmissions,
While outputting to electromagnetic control valve v5 and disengaging clutch 2,
A gear change is performed to achieve the set shift by outputting to the electromagnetic switching valve Vl-V4. When the gear change is completed, the main clutch 2 is engaged. When the clutch pedal 11 is depressed and the clutch operation switch 25 is turned on during automatic control, the command from the pedal takes priority and the automatic control is stopped.

When stopping the work, turn off the main key 14 to stop the engine rotation. At this time, when the main key 14 is turned off, the electromagnetic throttle valve 15 is switched and the amount of return oil from the hydraulic cylinder C5 is throttled to a small amount, so the internal pressure of the hydraulic cylinder C5 does not drop suddenly and the Since the main clutch 2 is in a disengaged state for a while, an unexpected start due to engine inertia is prevented.

Note that data indicating the states of the clutch 2, the main and auxiliary transmissions 4.5, the PTO clutch 7, and the PTO transmission are also transmitted to the engine control unit 27 and display unit 28.

[Effects of the Invention] As is clear from the above description, the transmission system for a traveling vehicle according to the present invention prevents the clutch from engaging due to a drop in oil pressure when the engine is stopped. Vehicles no longer start running, making it safer.

[Brief explanation of drawings]

FIG. 1 is a power transmission system diagram of a tractor as an example of the present invention, FIG. 2 is a hydraulic circuit diagram showing the main parts of a hydraulic system, and FIG. 3 is a block diagram of a speed change control device. 1...Engine, 2...Main clutch, 4...
Main transmission device, 5... Sub-transmission device, 6... Drive wheel,
8...Pro clutch, 9...PTO transmission, 1
5... Electromagnetic throttle valve, 20... Speed change control device.

Claims (1)

[Claims] A transmission system for a traveling vehicle that automatically performs clutch engagement/disengagement and gear change operations using hydraulic pressure, and is equipped with a transmission system that automatically performs clutch engagement/disengagement operations and gear change operations using hydraulic pressure. A transmission device for a traveling vehicle, characterized by being provided with an electromagnetic throttle valve that regulates the amount of oil returned from a hydraulic actuator.