JPH0297729A - Hydraulic driving device for dry clutch in industrial vehicle - Google Patents

Abstract

PURPOSE:To make it possible to perform stabilized cargo handling and travelling by setting both selector valves of a hydraulic circuit at a constantly closed state so as to maintain a connection-driving means at a fixed posture when no signal is outputted from a switching control means. CONSTITUTION:When an inching pedal is operated, CPU operates an exhaust side low speed opening/closing valve 26 of a hydraulic circuit 19 for driving a clutch to open, and when the clutch 2 becomes a half-closed state, CPU operates the opening/closing valve 26 to close. As a result, all four opening/ closing valves 23-26 in the hydraulic circuit 19 are closed so as to maintain the oil pressure in an actuator 10 at a fixed value, and the clutch is held at a half-closed state. Even when signal output from CPU is stopped due to failure of electrical system during inching travelling, no change in the oil pressure in the actuator 10 is produced and the connecting condition of the clutch 2 is not switched, since all the four, constantly closed opening/closing valves 23-26 are positioned at home-positions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic drive system for a dry single-plate clutch in an industrial vehicle.

[Prior Art] In an industrial vehicle equipped with an automatic transmission with a dry single-plate clutch, such as a forklift, the clutch connects and disconnects the engine and the automatic transmission according to the stroke of a clutch control cylinder in a hydraulic circuit.

That is, as shown in FIG. 5, the cylinder 57 that connects and disconnects the clutch is always disengaged by extending the rod 58 forward, which is biased toward the Rondo chamber, and contracting toward the piston chamber. I try to engage the clutch. The rod 58 is operated by controlling the pressure oil flowing into the piston chamber of the cylinder 57 using the hydraulic circuit 51. On the supply side of this hydraulic circuit 51, there are electromagnetic switching valves 52, 53 for high speed and low speed, and on the discharge side, there are electromagnetic switching valves 54, 54 for high speed and low speed.
55 are arranged respectively. The supply side switching valve 5
2.53 and the high-speed switching valve 54 on the discharge side are normally open, and only the low-speed switching valve 55 on the discharge side is normally open.

Then, based on the operation of the forward/reverse switching lever 50, etc., the controller 62 opens the switching valves 52 and 53 on the supply side.
By closing the switching valves 54, 55 on the discharge side, the rod 58 of the cylinder 57 is extended and the clutch is disengaged. On the contrary, the controller 62 controls the switching valves 52 and 53 on the supply side.
When the switching valves 54 and 55 on the discharge side are opened, the pressure oil in the piston chamber of the cylinder 57 is discharged by the rod 58, and the clutch is connected.

[Problems to be Solved by the Invention] However, in the above-mentioned hydraulic circuit 51, by making the low-speed switching valve 55 on the discharge side normally open,
When the controller 62 is cut off from the power supply due to a blown fuse or the like, the low speed switching valve 55 on the discharge side is returned to the communicating position. As a result, the pressure oil in the cylinder 57 is discharged to the drain side, the rod 58 contracts, and the clutch is unexpectedly connected. Therefore, when the vehicle is coasting downhill or inching, the clutch 59, which is in the disconnected or half-engaged state, is transferred to the engaged state against the driver's will, and the vehicle speed suddenly increases. Stable operation and work could not be guaranteed due to rising temperatures.

This invention was made to solve the above-mentioned problems, and its purpose is to avoid the start of the vehicle or sudden increase in vehicle speed caused by failure of the clutch electrical system when the engine is idling, thereby stabilizing the vehicle. An object of the present invention is to provide a hydraulic drive circuit for a dry single-plate clutch in an industrial vehicle that enables cargo handling and traveling.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a supply system whose switching is controlled according to the presence or absence of a signal from a switching control means based on the operation of an operation instruction means for instructing the vehicle to run or stop. A hydraulic circuit equipped with a side on-off valve and a discharge side on-off valve is provided, and the two on-off valves of the hydraulic circuit are connected via a connecting drive means, and the hydraulic pressure between the two on-off valves is controlled by switching control of these on-off valves. In a hydraulic drive system for a dry single-plate clutch in an industrial vehicle, which is provided with a clutch that moves according to the operation of a coupling drive means corresponding to changes in the engine and disconnects and connects an engine and an automatic transmission, the switching control means does not output a signal. The gist is that both switching valves of the hydraulic circuit are set to be normally closed in order to maintain the connecting drive means in a constant position.

By employing the above-described means, the present invention maintains both the switching valves on the supply side and the discharge side of the hydraulic circuit in the closed position when the switching control means does not output a signal, and the connecting drive means maintains a constant posture. The clutch is held in position to prevent movement of the clutch.

[Embodiment] Hereinafter, an embodiment in which the present invention is applied to a hydraulic drive device for a dry single-plate clutch in a forklift will be described in detail with reference to FIGS. 1 to 4.

In FIG. 2, the output of an engine 1 is transmitted to an automatic transmission 3 via a dry single plate clutch 2, and the output of the automatic transmission 3 is transmitted via a differential gear mechanism 4 to drive wheels 5 at a predetermined gear ratio. It is designed to drive forward and backward.

The dry single plate clutch 2 that cuts the output of the engine 1 moves between a fully engaged position and a completely disengaged position, and in the fully engaged position, its pressure plate 6 moves the clutch disc 8 into a flywheel by the biasing force of a spring 7. Acts to press against 9. And a piston rod 10 of a clutch drive actuator 10 constituted by a hydraulic cylinder.
When the lever a is about to protrude, the pressure plate 6 is moved in the direction away from the flywheel 9 via the lever 11, and the connection state of the clutch 2 is adjusted in accordance with the stroke amount of the piston rod 10a. is moved to the complete position where it is cut off from the output shaft. The stroke amount of the actuator 10 F10a (7) is detected by a clutch position sensor 2a consisting of a potentiometer.

On the other hand, the automatic transmission 3 is shifted between 1st speed (low speed) and 2nd speed (high speed) by driving the shift switching actuator 12, and the gear position is changed by driving the forward/forward switching actuator 13. is forward, neutral,
It can be switched to three positions, including reverse. Both the actuators 12 and 13 are constructed of hydraulic cylinders like the clutch drive actuator 10, and are driven by a hydraulic circuit shown in FIG. And the rod 13 of the forward/reverse switching actuator 13
The position of a is detected by a forward/reverse position sensor 14 consisting of a potentiometer, and three positions are detected: forward, neutral, and reverse. Further, the shift switching sensor 15 is also constituted by a potentiometer, and the shift switching actuator 1
The position of the second rod 12a is detected to detect two positions, 1st speed and 2nd speed.

As shown in FIG. 1, a pump 17 driven by a motor
After the pressure oil pumped up from the tank 16 is stored in the accumulator 18, it is transferred to the clutch drive hydraulic circuit 1.
9 and the transmission drive hydraulic circuit 20. The clutch drive hydraulic circuit 19 has high-speed and low-speed electromagnetic on-off valves 23 and 24 on the upstream side (supply side) of the central portion thereof.
However, further downstream (discharge side), high-speed and low-speed electromagnetic on-off valves 25 and 26 are arranged in parallel.

All of the on-off valves 23 to 26 are normally closed, and the amount of pressure oil in the clutch control actuator 10 is adjusted by opening and closing these valves.

Then, when the low-speed on-off valve 24 on the supply side is switched to the open position and the actuator 10 and the pump 17 are communicated with each other while holding both the on-off valves 25 and 26 on the discharge side in the closed position, pressurized oil flows into the actuator 10. Flows in and the piston rod 10a gradually extends from the actuator 10, so that the clutch 2 moves to the fully disengaged position and disconnects the engine 1 and automatic transmission 3.

In the above operation, when the high-speed on-off valve 23 is opened instead of the low-speed on-off valve 24 on the supply side, the actuator 10
The piston rod 10a of the piston rod 10a expands rapidly and is shut off faster.

In addition, in order to move the clutch 2 to the fully engaged position, both supply-side on-off valves 23 and 24 are closed, and the actuator 10
When the low-speed on-off valve 26 on the discharge side is opened, the rod 10 is closed by the biasing force of the spring.
a is pressed to the fully connected position side, the pressure oil in the actuator 10 flows out to the drain side, and the piston loft 10a of the actuator 10 gradually contracts. As a result, the clutch 2 moves from the half-clutch position to the fully engaged position, and the engine and transmission are connected.

In addition, in the above operation, the low speed on-off valve 24 on the supply side
When the high-speed switching valve 23 is opened instead, the piston rod 10a of the actuator 10 contracts rapidly, and the connection is performed more quickly.

In addition, in the transmission drive hydraulic circuit 20, the normally closed electromagnetic main on-off valve 27 is moved to the open position and communicated with the pump 17, and is further provided corresponding to the rod chamber 12b and piston chamber 12C of the shift switching actuator 12. The rod 12 is opened and closed by the two shift solenoid on-off valves 28 and 29.
The gear mechanism is operated by expanding and contracting a, and switching between 1st speed and 2nd speed is performed. Similarly, actuator 1 for forward/forward switching
By opening and closing two forward and reverse electromagnetic on-off valves 30 and 31 provided corresponding to the rod chamber 13b and piston chamber 13C of No. 3, the rod 13a is moved in and out, operating the gear mechanism, and switching between forward and backward movement is performed. .

Next, the electrical configuration of this embodiment will be explained with reference to FIG.

The accelerator opening sensor 32 consists of a potentiometer,
The amount of depression of an accelerator pedal 33 provided in the driver's cab is detected. Further, the lever position sensor 34 is composed of three limit switches, and the lever position sensor 34 is composed of three limit switches.
5 is in three positions: forward, neutral, and reverse.

Further, the inching sensor 40 detects when an inching pedal 41 in the driver's seat is depressed.

A central processing unit (hereinafter referred to as CPU) 36 inputs (No. 8 from the accelerator opening sensor 32, lever position sensor 34, and inching sensor 40 via an interface 37. The CPU 36 has a read-only memory (R)
OM) System memorized in 3B? Readable and writable memory (RAM) that operates based on the III program
39 temporarily stores the calculation results of the CPU 36.

The CPU 36 determines whether to start operating the accelerator pedal 33 based on the detection signal from the accelerator opening sensor 32, and when it determines that the pedal 33 is not operated, it maintains the clutch 2 in a fully engaged state. In order to do this, the on-off valves 23 and 24 of the clutch drive hydraulic circuit 19 are opened to drive and control the actuator 10. Furthermore, the CPU
36 determines the amount of depression of the accelerator pedal 33 at that time based on the signal from the accelerator opening sensor 32, rotates the engine 1 according to this, and also rotates the engine 1 based on the detection signal from the lever position detection sensor 34 at that time. Determine the operating position of the lever 35.

Then, the amount of depression of the accelerator pedal 33 at any given time is input manually from the accelerator opening sensor 32 to the CPtJ 36.

As shown in FIG. 3, the on-off valve 28.
The shift switching actuator 12 is driven and controlled via the actuator 29.

At the time of this switching, the supply side on-off valves 23, 24 of the clutch drive hydraulic circuit 19 are opened, and the discharge side on-off valves 25, 26 are kept closed, so that the actuator 1
0 and disconnects clutch 2.

Further, the CPU 36 determines whether the forward/reverse lever 35 is in the forward or reverse position based on the signal from the lever position detection sensor 34, and controls the opening/closing of the on-off valves 28 and 29 of the mission drive hydraulic circuit 20. As a result, the stroke amount of the rod 13a of the forward/reverse switching actuator 13 is adjusted, and the vehicle is moved forward or backward.

The CPU 36 determines that the inching pedal 41 has been operated based on the detection signal from the inching sensor 40,
The discharge side low-speed on-off valve 26 of the clutch drive hydraulic circuit 19 is opened, the opening IQa of the actuator 10 is gradually contracted, and the clutch 2 is moved toward the fully engaged position. The movement of this clutch 2 is monitored by a clutch position sensor 2a, and when the clutch 2 becomes a half clutch, a signal is output from the clutch position sensor 2a to the CPU 36.

Then, the CPtJ 36 stops outputting a signal to the discharge side low-speed on-off valve 26 and closes it. As a result, the four on-off valves 23 to 26 in the clutch drive hydraulic circuit 19 are all closed in order to keep the hydraulic pressure in the actuator 10 constant, and the clutch 2 is held in a half-clutch state.

During this inching run, due to a failure in the electrical system, C
Even if the signal output from the PU 36 is stopped, the four normally closed on-off valves 23 to 26 are all located at the home position, so that the clutch 2 can be connected without any change in the oil pressure inside the actuator 10. The state is never toggled.

Furthermore, when coasting downhill,
The forward/reverse lever 35 is held at the forward or reverse position without the accelerator pedal 33 being depressed, and the rotational force of the engine 10 is not transmitted to the automatic transmission 3. In this state, the on-off valve 23 of the clutch drive hydraulic circuit 19 is connected to CPLJ.
36, and the clutch 2 is in the fully disengaged position.

During the above-described coasting, when the operation of the CPU 36 is stopped due to a failure in the electrical system, the open on-off valve 23 returns to its home position, which is the closed position, but the on-off valve 25 and 26 positions on the discharge side Since this does not change, there is no possibility that the clutch 2 will engage against the driver's will.

In addition, in the above-mentioned Example, although the forklift was explained as an example, it is not limited to a forklift and can be applied to other industrial vehicles without charge.

[Effects] As detailed above, according to the present invention, it is possible to avoid changes in the engagement and disconnection of the clutch due to failures in the electrical system during coasting, inching, etc., and to achieve stable cargo handling and running. It has the excellent effect of making it possible.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of the clutch control system and automatic transmission control system in this invention, Fig. 2 is a mechanical diagram showing the mechanism of a drive system mainly consisting of an automatic transmission, and Fig. 3 is an electrical diagram of the invention. FIG. 4 is a diagram showing the shift state of the automatic transmission with respect to the vehicle speed and the amount of depression of the accelerator pedal, and FIG. 5 is a hydraulic circuit diagram showing a conventional example. Engine 1, clutch 2, automatic transmission 3, clutch actuator lO as connection drive means, clutch drive hydraulic circuit 19, supply side on-off valves 23, 24, discharge side on-off valves 25, 26, forward and backward movement as operation instruction means Switching lever 3
5. CPU36° as switching control means Patent applicant Toyota Industries Corporation Fujitsu
Co., Ltd.

Claims (1)

[Claims] 1. A hydraulic circuit is provided with a supply-side on-off valve and a discharge-side on-off valve whose switching is controlled according to the presence or absence of a signal from a switching control means based on the operation of various operation instruction means for instructing the running speed, direction, etc. of the vehicle, and Connected between both on-off valves of the same hydraulic circuit via a connecting drive means communicating therewith,
Hydraulic drive of a dry clutch in an industrial vehicle equipped with a clutch that connects and disconnects the engine and automatic transmission by moving according to the operation of the connecting drive means corresponding to changes in oil pressure between the two on-off valves due to switching control of these on-off valves. A hydraulic drive device for a dry clutch in an industrial vehicle, wherein both switching valves of the hydraulic circuit are set to be normally closed in order to maintain the connecting drive means in a constant position when the switching control means does not output a signal.