JPH0367731A - Hydraulic driving device for clutch in industrial vehicle - Google Patents

Abstract

PURPOSE:To obtain a quick engagement of a clutch by controlling the operating pressure of a clutch cylinder at the time of starting a vehicle by filling two accumulators with pressure to realize a shockless engagement of the clutch, and controlling the operating pressure by filling one accumulator with pressure. CONSTITUTION:A back and forth shifting shift booster 5 and a speed changing shift booster 6 are connected in series with a booster circuit 4 connected to a hydraulic pump 1, and a clutch cylinder 21 is connected through an inching valve 7 to a clutch circuit 8 branched by a flow dividing valve 3. Further, an operating gate valve 15 capable of being switched to an open position by booster operating pressure, and back and forth moving- and speed changing gate valves 16, 17 for releasing the clutch pressure into a tank only at the time of neutral, are provided to a clutch pressure control circuit 13 branched from the clutch circuit 8. Then, a first accumulator 18 for controlling the increase in clutch pressure at the time of starting a vehicle and a second accumulator 19 for controlling the increase in clutch pressure at the time of starting and speed changing are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic drive system for a clutch in an industrial vehicle such as a forklift.

<Prior Art> In an industrial vehicle equipped with a manual transmission with a hydraulically operated clutch, such as a forklift, when the gear position of the manual transmission is changed by operating the forward/reverse shift lever and the gear shift lever, In conjunction with this, the hydraulic valve of the clutch control hydraulic circuit is switched to connect or disconnect the clutch.

That is, the conventional clutch hydraulic drive device is shown as σ゛14th
In the circuit diagram shown in the figure, when the forward/reverse shift lever 201 is shifted to the forward or reverse position, the forward/reverse gear shift fork 202 is moved to change the forward/reverse gear position of the manual transmission, and the forward/reverse gear shift fork 202 is moved. The advance shift valve 203 is switched from the neutral closed position to the open position.

When the shift is completed, the pressure oil discharged from the hydraulic pump 204 is sent to the gate valve 206 for forward and backward movement via the regulator valve 205, and the gate valve 206 is
Let go. At this time, if the high-low gate valve (shift gate valve) 207 is in the open position, the hydraulic pump 20
4 and the clutch cylinder 208 of the clutch, the modulator valve 209 and the 7 cumulator 2 communicate with each other.
10, the clutch is connected while the rise of the oil pressure is regulated.

On the other hand, when the gear shift lever (high-low lever) 211 is shifted to the low speed position or high speed position, the high-low valve 212 is switched and the high-low shift valve 213 is switched from the neutral closed position to the open position by hydraulic pressure. , the gear shift fork 214 of the manual transmission is moved to change the gear position.Then, by switching the high-low shift valve 213 to the open position, the high-low gate valve 207 is switched to the open position, and at this time, 1yi reverse movement is performed. gate valve 20
6 is in the open position, the clutch is connected in the same way as in the above-mentioned forward/reverse operation.

Note that if either the forward/reverse shift lever 201 or the gear shift shift lever 211 is operated to the neutral position,
The gate valve 206, 207 is the clutch cylinder 2
08 to the tank 215, the clutches are all
I will be treated.

(Problem to be Solved by the Invention) However, in the case of the conventional device described above, the rise of the hydraulic pressure of the clutch cylinder 208 is always constant, that is, the rise of the hydraulic pressure of the clutch cylinder 208 is constant, that is, the rise of the hydraulic pressure of the clutch cylinder 208 is constant, that is, the rise of the hydraulic pressure of the clutch cylinder 208 is constant, that is, the modulator valve 209 and the accumulator 210 are Since there is a constant pressure increase control, if the hydraulic pressure rise time is set to be long to reduce the shock when starting, the clutch connection will be delayed when switching from low speed to high speed while driving, resulting in a large time lag. Conversely, when the rise time of the oil pressure was set short in order to reduce the time lag during traveling gear changes, there was a problem in that the shock at the time of starting was large.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a hydraulic drive system for a clutch in an industrial vehicle that can change the clutch engagement time between starting and when changing gears.

(Means for Solving the Problems) In order to solve the above problems, the present invention is configured as follows.

That is, a hydraulic drive system for a clutch in an industrial vehicle includes a clutch circuit that communicates between a hydraulic pump and a clutch cylinder, and a clutch pressure control circuit that is branched from the clutch circuit and communicates with a tank.

In the clutch pressure III/II] circuit, in conjunction with the shift operation of the forward/reverse shift lever of the manual transmission, the circuit is switched to a position where the circuit is opened at the neutral position and a position where the circuit is closed at the forward or reverse position. A gate valve for forward and backward movement, and a gate valve for shifting that can be switched to a position where the circuit is opened at the neutral position and a position where the circuit is closed at the shifting position in conjunction with the shift operation of the gear shift lever of the manual transmission. They are provided in parallel to each other.

Further, a check valve for blocking oil flow toward the clutch circuit is provided upstream of the forward/reverse gate valve, and a pressure increase adjustment valve is provided between the check valve and the forward/reverse gate valve. A 17th ↓ neemulator is provided, and furthermore, a second accumulator for promotion adjustment is provided upstream of the shift gate valve.

(Operation) In the clutch hydraulic drive system of the present invention configured as described above, when the forward/reverse gear position and the shift gear position of the manual transmission are respectively in the neutral state, the forward/reverse drive gate valve and the shift gate valve are in the neutral state. Both are held in the open position, so the clutch pressure control circuit is communicated with the tank and the clutch is quickly disengaged.When starting, the forward/reverse shift lever is shifted to the forward or reverse side, and the gear shift lever is When the shift lever is shifted to the low speed position, the gate valves for forward/reverse and gear shifting are switched to the closed position, and the clutch pressure control circuit is disconnected from the tank.Therefore, the hydraulic pressure in the clutch circuit system increases. The clutch is then connected, and at this time, the rise of the oil pressure in the clutch cylinder is controlled by two accumulators, a first accumulator and a second accumulator, in the clutch pressure control circuit.

Regarding the first accumulator on the side of the forward/reverse gate valve, the check valve prevents pressure oil from flowing out unless the forward/reverse gate valve is returned to the neutral open position. Therefore, when the gear position of the manual transmission is operated from the low speed side to the high speed side by the speed change shift lever while driving, and the speed change gate valve is operated from the low speed position to the high speed position in conjunction with this, the gate When the valve is switched to the open position, which is the neutral position, the pressure oil accumulated in the second accumulator is discharged to the tank, and the clutch moves to ij1! The clutch cylinder operates when the clutch cylinder is switched to the closed position, which is a high-speed position, but the rise of the oil pressure of the clutch cylinder at this time is controlled by only the second accumulator.

In other words, the operating pressure of the clutch cylinder at the time of starting is controlled by the filling of two accumulators, which enables clutch connection with less shock, and the operating pressure of the clutch cylinder at the time of shifting is controlled by the filling of one accumulator. Since it is To control, it is possible to quickly and fairly latch connect by quickly boosting the voltage.

(Example) Hereinafter, an example of the present invention will be specifically described based on the drawings.

(Example 1) First, Example 1 of the present invention will be described based on FIGS. 1 to 9. The hydraulic circuit diagram C in Fig. 1 shows the hydraulic operating system of the latch, in which the pressure oil discharged from the hydraulic pump 1 is divided by a flow divider valve 3, and one side is connected in series to the booster circuit 4 for forward and backward movement. It communicates with the tank 2 through a shift booster 5 and a gear shift booster 6, and the other communicates with a clutch cylinder 21 through a clutch circuit 8 provided with an inching valve 7. The booster circuit 4 is provided with a relief valve 9 that sets the maximum operating pressure of the shift booster 5.6, and the clutch circuit 8 is provided with a regulator valve 10 that sets the maximum operating pressure of the clutch cylinder 21.

Further, the shift boosters 5.6 for forward/reverse movement and gear change are respectively operated by a forward/reverse movement shift lever 11 and a speed change shift lever 12 for changing gear positions of the manual transmission.

Between the inching valve 7 and the clutch cylinder 21, a clutch pressure control circuit 13 branched from the clutch circuit 8 is switched to the open position by the booster operating pressure applied via the pilot line 14, and releases the clutch pressure to the tank. two gate valves 16 and 17, one for forward/reverse movement and the other for gear shifting, to release the clutch pressure to the tank only when in neutral, and a gate valve 16 and 17 for controlling the increase in clutch pressure at the time of starting. 1 accumulator 1
8, a second accumulator 19 for controlling the increase in clutch pressure at the time of starting and shifting, and a check valve 20 for preventing the pressure oil in the first accumulator 18 from flowing out to the clutch circuit 8 side. ing.

The operation gate valve 15 and the forward/backward advancement gate valve 1
6 and the gate valve 17 for shifting are arranged in parallel with each other in the clutch pressure control circuit 13, and the gate valve 16 for forward/reverse traveling and the gate valve 17 for shifting are connected to the shift booster for forward/reverse traveling and shifting. 5.6 and is mechanically connected. The check valve 20 is arranged upstream of the gate valve 16 for forward and backward movement, and the first accumulator 18 is connected between this check valve 20 and the gate valve 16 for forward and backward movement. Further, the second accumulator 19 is made up of a combination of an accumulator 191 and a modulator valve 192, and is connected to the upstream side of the shift gate valve 17.

Figure 2 shows a general two-speed forward/reverse manual transmission used in forklifts, etc., in which the two shift shafts 33 and 34, one for forward/forward movement and the other for shifting, are used for forward/reverse movement. and the output shaft 52 of the shift booster 5.6 for speed change.
By sliding in the axial direction, the gear position is changed via the shift forks 35 and 36, and the changed position is maintained by the detect 3 f.

In addition, in Fig. 2, 38.39 is a pair of low speed gears,
40.41 is a pair of high speed gears, 42.43 is a pair of forward gears, 44.45 is a pair of reverse gears, 46 is an input shaft, and 47 is an output shaft.

Next, FIG. 3 shows the specific structure of the shift booster 5.6, and the structure is the same for both forward and backward movement and for shifting. Shift levers 11, 12 for forward/forward movement or gear change
The input shaft 51 operated by the output shaft 5
2, and the output shaft 52 is movable in the axial direction relative to the housing 53. And shift lever 11
, 12 is in the illustrated position when the pump boat 5 is neutral.
4, left and right cylinder chambers 55, 56, and left and right reaction force chambers 5.
7.58 (the left reaction force chamber 57 also serves as a spring storage chamber) and the tank boat 59 are in communication, and the pressure oil is discharged to the tank 2.

In the illustrated state, when the input shaft 51 is moved to the right side in the figure, the pulse 1 gaps 62 and 64 between the land portion of the valve body 60 that moves together with the output shaft 52 and the land portion of the input shaft 51 are closed, and pressure acts on the left cylinder chamber 55 and the right reaction force chamber 58.

Therefore, in the reaction force chamber 58, the force at the pressure receiving area of al-a2 is applied to the input shaft 51 as a reaction force, and the shift lever
Transmit the operation reaction force to 11 and 12.

On the other hand, in the cylinder chamber 55, the output shaft 52 is moved to the right in the figure by the force of the pressure receiving area of Al-A2.

In other words, if we omit the reaction force caused by the spring 65, the output shaft 51 will move by the stroke of the input shaft 51.
2 is operated with an increased force in the ratio of A1-A2/a1-a2, and moves the shift shaft 33 or 34 of the manual transmission to change the gear position, and also operates the gate for forward/reverse movement or the transmission. Switch valves 16 and 17.

When the shift operation of the shift levers 11 and 12 is completed, the valve gaps 62 and 64 are opened by the relative movement between the output shaft 52 and the input shaft 51, and the pump boat 54 communicates with the tank boat 59. In other words, while the shift boosters 5 and 6 are in operation when the shift levers 11 and 12 are operated, the operating pressure in the booster circuit 4 becomes high, but as soon as the shift operation is completed, it flows into the tank 2 and becomes low pressure or zero. .

Note that when the input shaft 51 is moved to the left side in the figure,
Since the valve gaps 61 and 63 between the land portion of the valve body 60 and the land portion of the input shaft 51 are respectively closed, pressure oil does not act on the right cylinder chamber 55 and the left side reaction chamber 57 at this time. and the output shaft 5
2 is moved to the left in the figure.

Figure 4 shows each gate valve 15, 16, 17 and check valve 2.
0, and as mentioned above, each gate valve 16.17 for forward/reverse movement and gear change is connected to the output shaft 52 of the shift booster 5.6 for forward/reverse movement and gear change, respectively. and they are connected to the gate valve 16 when the manual transmission is in the neutral position.
．． Each of the 17 clutch boats 161, 161° and the tank boat 162 are communicated with each other, and both the clutch boats 161, 161° and the tank boat 162 are cut off at positions other than the neutral position.

Further, the operating gate valve 15 connects the clutch boat 161° of the gear shifting gate valve 17 and the tank boat 162 by using a pilot pressure lower than the operating pressure of the shift booster 5.6 acting through the pilot line 14, and transfers clutch pressure to the tank. It is designed to be removed. That is, it is switched to the open position only when the shift booster 5.6 is in operation, and is kept in the closed position at other times. Furthermore, the check valve 20 and the gate valve 16 for forward and backward movement are connected to the tank boat 162.
When the first accumulator boat 163 is shut off, the pressure oil in the first accumulator 18 shown in FIG.

Next, FIG. 5 is a detailed view of the second accumulator 19, which is used in a transmission with a torque converter, etc. and is composed of an accumulator 191 and a modulator valve 192.
3 on the right side of the drawing, and acts on the left side of the accumulator piston 195 through the orifice 194.

At the beginning of pressurization, the leftward pressing force acting on the modulator piston 193 overcomes the modulator spring 196 and moves the modulator piston 193 to the left, creating a balanced pressure in the gap formed between the modulator piston 193 and the tank boat 197. (up to point A shown in Figure 9), and as the pressure rises further, the seventh cumulator piston 195 begins to move to the right, increasing the set load of the modulator spring 196, and reducing the pressure in the circuit to point A in Figure 9. raise it from to point B. Furthermore, the accumulator piston 195 moves over the accumulator spring 198 until it is stopped by the modulator piston 193, which causes the pressure to rise to the maximum pressure shown at point 0 in FIG. Note that the pressure oil on the accumulator piston side is returned through a check valve 199.

Next, FIG. 6 is a detailed view of a general inching valve 7 and a regulator valve 10 used in a transmission with a torque converter. The inching valve 7 regulates the clutch pressure by a balance between an inching reaction spring 72 that presses the inching piston 71 to the right side in the figure, and an inching spring 74 that is supported by the inching shift shaft 73 and presses the inching piston 71 to the left side in the figure. Inching shift shaft 7
3 is mechanically connected to a pedal 75, and is always held at the position shown in the figure, pressed by an inching set spring 76. At this time, the pump boat 77 and clutch boat 78 are in communication, and the tank boat 79 is in communication with the pump boat 77. Although the inching shift shaft 7 is blocked, the inching shift shaft 7 can be opened by operating the pedal.
3 is moved to the right in the figure, the set load of the inching spring 74 changes corresponding to the amount of movement, and the operating pressure of the inching piston 71 changes. As a result, the inching piston 71 moves to the right in the figure, and the pump boat 7
7 communicates with the clutch boat 78 and tank boat 79, or the pump boat 77 is disconnected and the clutch boat 78 communicates with the tank boat 79.

That is, the clutch can be connected or disconnected by operating a pedal of the inching valve 7.

Next, FIG. 7 is a detailed view of the clutch, in which pressure oil is passed from the rotary valve 23 fixed to the clutch housing 22 via a rod 31 to the clutch cylinder 21 through an oil passage 25 formed in the clutch cover 24. is sent to the clutch brake II plate 27 via the piston 26.
Power is transmitted between the clutch disc 30 on the input shaft 29 and the flywheel 28.

This embodiment is constructed as described above, and its operation will be explained below.

Figure 8 shows all the shift patterns that can be operated by a two-speed forward/reverse transmission; in the figure, N is the neutral position;
F indicates a forward position, R indicates a reverse position, 1 indicates a low speed position, and 2 indicates a high speed position. Also, the white arrows indicate the first and second
A slow connection when the clutch is connected using two accumulators 18 and 19, a quick connection when the clutch is connected using only the first accumulator 18, and a dashed arrow means the clutch is not connected. Each is shown below.

Among various shift patterns, the case of the most simple IfA shift operation will be described as an example.

When the shift levers 11 and 12 for forward/reverse movement and gear change are in their neutral positions, both shift boosters 5 and 6 are in their neutral positions, and therefore, the flow is sent from the hydraulic pump 1 to the booster circuit 4 through the dividing valve 3. The released pressure oil is returned to tank 2. In addition, a gate valve 16 for forward and backward movement and shifting
．． 17 are both in the open position, the pressure oil sent to the clutch circuit 8 through the flow divider valve 3 is transferred to the clutch pressure control circuit 13.
The clutch is therefore in a disengaged state.

Therefore, when the gear shift lever 12 is shifted to the lower speed side in order to start the vehicle, the input shaft 51 of the gear shift booster 6 is moved, and accordingly, the output shaft 52 is moved to the input shaft 51 as described above. By being moved in the same direction, the shifting gear position of the manual transmission mechanically connected to the manual transmission is switched to the low speed side, and the shifting gate valve 17 is also switched to the closed position. The advance gate valve 16 remains open, so the clutch is held disengaged.

In this state, if you shift the forward/reverse shift lever 11 to the forward or reverse side, the forward/reverse shift booster 5
The input shaft 51 of the input shaft 51 is moved, and the output shaft 52 is accordingly moved in the same direction as the input shaft 51, so that the forward/reverse gear position of the manual transmission mechanically connected to the output shaft 52 is moved forward. At the same time, the gate valve 16 for forward and backward movement is switched to the closed position, and the clutch pressure control circuit 13 is quickly disconnected from the tank 2. Therefore, the clutch pressure υJll1 circuit 1
3, clutch circuit 8, and clutch cylinder 21 rise to the set pressure of regulator valve 10, and the clutch is connected.

At this time, the first accumulator 18 and the second
The pressure increase time is controlled by the two accumulators including the accumulator 19, that is, the oil pressure rises slowly, and the clutch is connected slowly.
Smooth starting without shock is possible.

In addition, during the above-mentioned starting operation, the operating gate valve 15 of the clutch pressure control circuit 13 is switched to the open position while the shift booster 5.6 is operating as described above, but returns to the closed position upon completion of the shift. be done.

On the other hand, when shifting from low speed to high speed, when the shift lever 11 is operated to remove the low speed gear, the operation pressure of the shift booster 6 moves the operation gate valve 15 from the previous vRw4 position. When the shift booster 6 is switched to the open position, that is, when the shift booster 6 is in operation, the pilot pressure acting through the pilot line 14 as the pressure in the booster circuit 4 increases switches the operating gate valve 15 to the open position, so that the pressure in the clutch cylinder 21 increases. It is drained to tank 2 and the clutch is disengaged. That is,
After the clutch is disengaged, the low gear will be disengaged.

Further, when the operation gate valve 15 is switched to the open position, the pressure oil accumulated in the second accumulator 19 is discharged to the tank 2 similarly to the clutch cylinder 21, but the first accumulator 18 is in the closed position for forward and backward movement. The outflow is prevented by the gate valve 16 and the check valve 20, and the accumulated pressure is maintained. Then, when the manual transmission is switched from the neutral position to a high gear and the transmission gate valve 17 is switched to the closed position, the clutch pressure increases again and the clutch is connected.
Since the pressure increase in this case is controlled only by the 27th cumulative regulator 19, the back pressure is increased to the set pressure of the regulator valve in a shorter time than at the time of starting, and the clutch is quickly connected. It should be noted that when switching the shift gate valve 17, the shift gate valve 17 is first switched to the open position corresponding to the neutral position and then switched to the closed position, so even if the operation gate valve 15 is not provided. Also, the clutch system pressure, that is, the pressure of the second accumulator 19 and the clutch cylinder 21 can be released to the tank 2.

Furthermore, the accumulated pressure in the first accumulator 18 is released to the tank 2 only when moving from forward to reverse or vice versa.
This operation is the same as starting a vehicle, and quick engagement of the clutch is not necessary; slow engagement is effective.

Furthermore, clutch engagement R1bl due to pressure increase control of the first accumulator 18 and second accumulator 19 described above
When more delicate machine control than J ill is required, the inching valve 7 is created by the operator's operation of the pedal 75, that is, the inching valve 7 of the inching piston 71 shown in FIG.
By changing the set load in step 4, the clutch pressure can be controlled and the clutch can be disconnected or connected as appropriate.

Therefore, such first and second accumulators 1
The clutch pressure increase and IJ control according to 8.19 is performed as shown by the white arrow or solid line arrow in the shift pattern of FIG. The pressure increase υ control is performed by the second accumulator 19, and the clutch is connected slowly, and when shifting from low speed to high speed or vice versa, the pressure increase control is performed only by the second accumulator 19, and the clutch is quickly connected.

(Example 2) Next, Example 2 shown in FIG. 10 will be described. This embodiment 711fM2 differs from the embodiment 1 shown in FIG. 1 in that the branch point of the clutch circuit 8 of the clutch pressure control circuit 13 is set between the flow dividing valve 3 and the inching valve 7, and the other configurations are as follows. This is the same as in the first embodiment. Therefore, the same actions and effects as in the first embodiment can be obtained.

(Example 3) Next, Example 3 shown in FIG. 11 will be described. In this third embodiment, in the second accumulator 19, in place of the orifice 194 and check valve 199 of the first embodiment, a switching valve 2QO is provided which can return the accumulated pressure directly to the tank 2 when releasing the accumulated pressure in the accumulator 191. The hydraulic shift mechanism is changed from the shift boosters 5 and 6 of the first embodiment to a simple combination of a switching valve 90 and a shift cylinder 91. However, the switching valve 90 uses a spring offset type that automatically returns to the neutral position after a shift operation. Therefore, in the case of this third embodiment, the same operation and effect as in the first embodiment can be obtained.

(Example 4) Next, Example 4 shown in FIG. 12 will be described. In this fourth embodiment, the structure of the shift gate valve 17 is changed, and the 37th cumulator 93 is not filled when switching to the low speed side, but is filled when switching to the high speed side.
is added. Therefore, the operation of each of the first to third 7-cumulators 1B and 19.93 during a shift operation is as shown in FIG. 13. However, in FIG. 13, the first accumulator 18 is shown as ■, the second accumulator 19 is shown as ■, and the third accumulator 93 is shown as ■.

That is, when starting at a low speed, the clutch pressure is increased by 1 by the first accumulator 18 and the second accumulator 19.
1JIll, and the clutch is connected slowly. On the other hand, when starting at high speed, the total accumulator of 311 is 18.1
The boost MIg is 9.93, and the clutch is super fast.
It becomes a connection. Also, when shifting from low speed to high speed, the 27th
Pressure increase control is performed by the cumulator 19 and the 37th cumulator 93, and the clutch is quick-connected. Roughly speaking, when shifting from high speed to low speed, the pressure is increased by the second accumulator 19, and the clutch is connected very quickly.

That is, in accordance with the fourth embodiment, by appropriately adjusting the capacity of each of the first to third 7 cumulators 18, 19, 93, the 11
Control becomes possible.

Although the present embodiment has been described assuming that the gear change of the manual transmission is carried out by hydraulic pressure, it is also possible to apply a system in which the gear change is carried out mechanically without paying attention to this.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to slowly engage the clutch at the time of starting, and start without or with little shock, and also to quickly engage the clutch, and to quickly engage the clutch at the time of shifting. It is possible to change gears.

[Brief explanation of drawings]

1 to 13 show embodiments of the present invention, FIG. 1 is a hydraulic circuit diagram of the clutch control system of embodiment 1, FIG. 2 is a sectional view of a manual transmission, and FIG. 3 is a diagram of a shift booster. Fig. 4 is a sectional view showing the specific structure of each gate valve and check valve, Fig. 5 is a sectional view of the second accumulator, Fig. 6 is a sectional view of the inching valve, and Fig. 7 is a sectional view of the clutch. , FIG. 8 is an explanatory diagram showing the shift pattern and clutch connection mode of a two-speed forward/reverse manual transmission, FIG. 9 is an ascending diagram of the second accumulator, and FIG. 10 is a hydraulic diagram showing the second embodiment. Circuit diagram, Fig. 11 is a hydraulic circuit diagram showing Embodiment 3, Fig. 12
13 is a hydraulic circuit diagram showing a fourth embodiment, FIG. 13 is an explanatory diagram showing a clutch connection mode in a shift pattern in the fourth embodiment, and FIG. 14 is a hydraulic circuit diagram of a conventional clutch III III system. 17... Speed change gate valve 18... First accumulator 19... 27th accumulator 20... Check valve 21... Clutch cylinder

Claims (1)

[Claims] It is equipped with a clutch circuit that communicates between the hydraulic pump and the clutch cylinder, and a clutch pressure control circuit that is branched from this clutch circuit and communicates with the tank. The gate valve for forward and backward movement is switched to a position that opens the circuit in the neutral position and closes the circuit in the forward or reverse position in conjunction with the shift operation of the gear shift lever of a manual transmission. A clutch gate valve is provided in parallel with each other, and the gate valve is placed in a position that opens the circuit in the neutral position and closes the circuit in the shift position, and a clutch circuit is provided upstream of the gate valve for forward and backward movement. A check valve is provided to prevent the oil from flowing to the side, and a first accumulator for pressure increase adjustment is provided between the check valve and the forward/reverse gate valve, and a first accumulator is provided upstream of the shift gate valve. This is a hydraulic drive device for a clutch in an industrial vehicle, which is equipped with a second accumulator for boost adjustment.