JPH1135299A - Hydraulic circuit of industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit of industrial vehicle which allow to run by converting a passage to feed and exhaust the operation oil to a damper, to the non-current-carrying condition and the communicating condition by a manual operation, regardless of a solenoid control valve, when the damper is in a lock condition and running is difficult, even though the solenoid control valve to cut off the passage is used in a power nonfeeding condition. SOLUTION: A damper 12 is provided between a body frame 1a and a rear axle 11, and it feeds and exhausts the operation oil according to the oscillation of an axle. A shut-off valve 13 converts passages P1 to P3 to let flow the operation oil in the power nonfeeding time, to a cutoff condition so as to make the damper 12 in the lock condition, and converts the passages P1 to P3 in the communicating condition in the power feeding time so as to make the damper 12 in the unlocked condition. A controller C controls the valve 13 to convert the communicating and the cutoff conditions. A manual operation valve 21 converts the passages P1 to P3 in the cutoff and the communicating conditions by a manual operation, regardless of the converting operation of the above valve 13 to the cutoff condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for an industrial vehicle having an axle swingably provided.

[0002]

2. Description of the Related Art Conventionally, forklifts have been proposed in which an axle can be swung with respect to a body frame in consideration of the traveling performance and riding comfort of the vehicle. In this forklift,
When the forklift turns, it swings according to, for example, lateral acceleration (centrifugal force). For this reason, the running stability at the time of turning was reduced, and the running speed could not be increased.

Japanese Patent Application Laid-Open No. 58-211903 has provided a turning detecting means for detecting a centrifugal force generated at the time of turning of a forklift. When the detected value of the centrifugal force exceeds a predetermined value, the swinging operation is performed. A technique has been proposed in which an axle that is supported is fixed by an axle fixing mechanism.

[0004] In this forklift, when the centrifugal force acting on the lift during turning of the forklift becomes a predetermined value or more, the turning can be performed in a stable state with the axle fixed.

The axle is fixed by locking a damper disposed between the body frame and the axle. That is, by blocking the passage for supplying and discharging the hydraulic oil to the damper so that the damper cannot supply and discharge the hydraulic oil, the damper is locked and the axle is fixed. Further, by making the passage communicated, the locked state of the damper is released, and the axle can swing.

[0006] The blocking of the passage and the switching of the communication state are performed based on the excitation and non-excitation of the electromagnetic control valve. This electromagnetic control valve uses a so-called normally open type in which the passage is in a communicating state in a non-excited state. This is because, for example, when the forklift is running, the electromagnetic control valve controls the passage in the communicating state for a long time, so that controlling the passage in the communicating state when in the non-excited state can contribute to lower power consumption. It is.

[0007]

However, when the electric system of the forklift breaks down, the power supply to the electromagnetic control valve is cut off and the control valve is de-energized. Then, the damper is in an unlocked state, and the vehicle body frame and the axle are always in a swingable state. In this state, the running stability at the time of turning of the forklift is reduced as described above.

In order to solve the above problem, a so-called normal shutter is used to shut off the passage when the electromagnetic control valve is not energized (de-energized).
It is conceivable to use a square shape. If you do this,
When the electric system of the forklift breaks down, the damper is locked and the body frame and the axle are fixed, so that the traveling of the lift during turning is stable. However, simply using a normal-closed type electromagnetic control valve, when forced to move to repair a forklift, etc., when the damper is in a locked state, for example, one of the drive wheels due to unevenness of the road surface In some cases, it may be difficult to travel due to being lifted off the road surface.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to use an electromagnetic control valve for shutting off a passage for supplying and discharging hydraulic oil to and from a damper in a non-energized state. Even when the traveling is difficult in the locked state of the damper, the hydraulic circuit of the industrial vehicle is capable of manually switching the passage between the closed state and the communicating state regardless of the control valve to enable traveling. It is in.

[0010]

According to a first aspect of the present invention, there is provided an industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame, the industrial vehicle being disposed between the body frame and the axle. A damper for supplying and discharging hydraulic oil in accordance with the swing of the axle, and a passage for flowing hydraulic oil supplied and discharged from the damper when not energized is switched to a cutoff state to lock the damper, An electromagnetic control valve for switching the electromagnetic control valve to an open state by switching the electromagnetic control valve to an open state, a fixed control means for controlling the electromagnetic control valve to be switched to an open state or a closed state, and switching of the electromagnetic control valve to a closed state The gist of the present invention is that a manual operation valve for switching the passage to a shut-off state or a communication state by a manual operation regardless of the operation is provided.

According to a second aspect of the present invention, there is provided a supply system which is connected to a passage through which hydraulic oil supplied and discharged from the damper flows, and which supplies the hydraulic oil to keep the hydraulic oil pressure flowing through the passage constant. And a backflow prevention means provided between the supply means and the passage for preventing backflow of the hydraulic oil from the passage to the supply means.

According to a third aspect of the present invention, at least one of the electromagnetic control valve, the manually operated valve, the supply means, and the backflow prevention means is integrally assembled to the body of the damper. .

According to the first aspect of the present invention, the damper is disposed between the vehicle body frame and the axle, and supplies and discharges the hydraulic oil according to the swing of the axle. The electromagnetic control valve switches the passage through which the hydraulic oil supplied and discharged from the damper flows when the power is not supplied to the shut-off state to lock the damper, and switches the communication path to the communication state when the power is supplied to bring the damper into the unlocked state. . The fixed control means controls the electromagnetic control valve to switch to a communication state or a cutoff state. The manually operated valve manually switches the passage to the cutoff state or the communication state regardless of the switching operation of the electromagnetic control valve to the cutoff state. Therefore, even if an electromagnetic control valve that shuts off the passage in the non-energized state is used, when the damper is locked and traveling is difficult, the passage is manually switched between the shut-off state and the communication state regardless of the control valve. Can be run.

According to the second aspect of the present invention, the supply means is connected to the passage through which the hydraulic oil supplied / discharged from the damper flows, and the supply means is operated to keep the hydraulic pressure of the hydraulic oil flowing through the passage constant. Supply oil. The backflow prevention means is provided between the supply means and the passage, and prevents backflow of the hydraulic oil from the passage to the supply means. Therefore, even if the hydraulic oil leaks, the hydraulic pressure of the hydraulic oil flowing through the passage can be kept constant by the supply means and the backflow prevention means, so that the locking effect of the axle with respect to the vehicle body frame is not reduced.

According to the third aspect of the invention, at least one of the electromagnetic control valve, the manually operated valve, the supply means, and the backflow prevention means is integrally assembled to the body of the damper. Therefore, it is possible to omit the electromagnetic control valve, the manually operated valve, the supply unit, the support member for supporting the backflow prevention unit, and the like, thereby contributing to a reduction in the cost of the industrial vehicle and a reduction in the number of assembling steps.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a side view showing the forklift 1 as an industrial vehicle. The forklift 1 has a pair of left and right outer masts 2 at its front.
The inner mast 3 is provided between the outer masts 2 so as to be able to move up and down. Fork 4 for Inna Mast 3
Are arranged so as to be able to move up and down. That is, the fork 4 moves up and down along the outer mast 2.

The outer mast 2 is a forklift 1
Is connected to the vehicle body frame 1a via a tilt cylinder 5, and a piston rod 5a of the cylinder 5
Is tilted based on the expansion / contraction drive. The lift cylinder 6 disposed on the back surface of the outer mast 2 has a piston rod 6a connected to the upper end of the inner mast 3, and the fork 4 moves up and down based on the expansion and contraction drive of the rod 6a.

A pair of left and right front wheels 7 are provided at the front of the body frame 1a of the forklift 1. Each front wheel 7
Is connected to the engine via a differential ring gear (not shown) and a transmission (not shown), and each front wheel 7 is driven by the engine. That is, the front wheels 7 are driving wheels.
Also, at the rear of the body frame 1a of the forklift 1,
Left and right rear wheels 8 are provided.

FIG. 1 shows a connecting structure for connecting the rear wheels 8. A rear axle 11 extending in the vehicle width direction is provided at the rear lower portion of the body frame 1a of the forklift 1 so as to be able to swing (rotate) about a center pin 11a. The rear wheels 8 are provided on both left and right sides of the rear axle 11.
Are connected. The rear wheel 8 is a steering wheel 1 in the cab 9
The steering wheel is steered based on the operation of “0”. The rear axle 11 forms an axle connecting the two rear wheels 8.

A hydraulic damper (hereinafter simply referred to as "damper") 12 is connected between the body frame 1a and the rear axle 11. The damper 12 is a double-acting hydraulic cylinder. That is, the damper 12 is connected to the rear wheel 8
It absorbs the force acting on

As shown in FIGS. 3 and 4, the damper 12 includes a substantially cylindrical body 12a and a piston 12b disposed in the body 12a. Piston 12
The piston rod 12c is connected to b. The rear axle 11 is connected to the tip of the piston rod 12c.

The interior of the damper 12 is partitioned by a piston 12b into a first chamber R1 and a second chamber R2. 1st, 2nd
First and second passages P1, P2 formed in the body 12a are connected to the chambers R1, R2, respectively. First
The passage P1 extends toward a shut-off valve 13 as an electromagnetic control valve mounted on the body 12a.

The shut-off valve 13 is a cylindrical body 1
4 and a substantially cylindrical spool 15 inserted into the body 14
And The body 14 has first to third communication holes E.
1 to E3 are formed. The first passage P1 is connected to the first communication hole E1. The first communication chamber Q1 is formed by the base end portion 15a of the spool 15 and the inner peripheral surface of the body 14.
Is formed in the communication chamber Q1, and the first and second communication holes E1,
E2 is connected.

The spool 15 has a circumferential groove 15b. A second communication chamber Q2 is formed by the groove 15b and the inner peripheral surface of the body 14, and the third communication hole E3 is connected to the communication chamber Q2. The third communication hole E3 has a small diameter. That is, the third communication hole E3 is the fixed throttle valve 16, and limits the flow rate of the working oil flowing through the hole E3.

A spring 17 is interposed between the base end 15a of the spool 15 and the body 14, and the first communication chamber Q1 and the second communication chamber Q2 are separated by the spool 15 urged by the spring 17. Is blocked. The movement of the spool 15 is controlled by the electromagnetic solenoid 1 provided in the shut-off valve 13.
8 based on the excitation (energization) and the non-excitation (non-energization). The switching between the excited state and the non-excited state of the electromagnetic solenoid 18 is performed by a controller C as fixed control means connected to the solenoid 18 as shown in FIG.

Normally, when the forklift 1 is started, the electromagnetic solenoid 18 changes from a non-excited state to an excited state, and a plunger 18a provided on the solenoid 18 protrudes, and the spool 15 moves against the urging force of the spring 17. Is done. Then, the first communication room Q1 and the second communication room Q2 enter a communication state. On the other hand, when the controller C controls the rear axle 11 to be fixed to the vehicle body frame 1a, the electromagnetic solenoid 18 changes from the excited state to the non-excited state, and the spool 15 moves by the urging force of the spring 17 to move to the first position. The first communication room Q1 and the second communication room Q2 are cut off.

The spool 15 has a through hole 15c formed in the axial direction thereof. The through hole 15c allows the first communication chamber Q1, the spool 15, and the plunger 1
8a and the gap D interposed between them. That is, even if the hydraulic pressure of the first communication chamber Q1 is high,
By 5c, the hydraulic pressures of the working oil in the communication chamber Q1 and the gap D are kept substantially equilibrium, so that the spool 15 can be easily moved.

The third communication hole E3 is provided with the damper 1
The third passage P3 formed in the second body 12a is connected. The third passage P3 extends toward a check valve 19 as a backflow prevention means assembled to the body 12a. A first connection space F1 and the body 2 are provided between a body 20 having a check valve 19 and the body 12a.
A second connection space F2 is formed on the opposite side of the space F1 with respect to 0, and a third passage P3 is connected to the space F1.

In the first connection space F1, the body 1
The second communication hole E2 of the shutoff valve 13 is connected via a bypass passage P4 formed in 2a. As shown in FIG. 5, the bypass passage P4 is provided with a manual valve 21 as a manually operated valve that is operably mounted from the outside of the body 12a. The manual valve 21 is connected to the body 12a
The bypass passage P4 is switched to a communicating state or a shut-off state even when the shut-off valve 13 is in a shut-off state based on a manual operation from the outside of the above, and the shut-off valve 13 is normally in a shut-off state.

The first connection space F1 is connected to the second connection space F2 via a bypass space 20a formed through the body 20 to constitute the check valve 19. A second passage P2 extending from the second chamber R2 is connected to the second connection space F2.

The bypass space 20a has a connection hole 20
The storage chamber 23 of the accumulator 22 as a supply means formed in the body 20 is connected via b.
A valve body 19a is provided in the bypass space 20a, and the valve body 19a closes the connection hole 20b to shut off the space 20a and the storage chamber 23 by the urging force of the spring 19b. At this time, even if the hydraulic pressure of the hydraulic oil on the damper 12 side rises, the valve body 19a does not move because it is in contact with the passage opening of the connection hole 20b, and the valve body 19a does not move from the damper 12 side to the accumulator storage chamber 23. There is no oil backflow.

The body 24 of the accumulator 22 is fitted to the body 20 of the check valve 19. A gas chamber 25 is formed in the body 24 of the accumulator 22,
The gas chamber 25 and the storage chamber 23 are partitioned by a pressing piston 26. For example, air compressed at a predetermined pressure is sealed in the gas chamber 25, and the pressing piston 26 is pressed by the expansion force of the air. The operating oil filled in the storage chamber 23 has a predetermined pressure by the pressed pressing piston 26.

Normally, the valve body 19a of the check valve 19 is configured so that the oil pressure on the damper 12 side is higher than the oil pressure in the storage chamber 23 which has been increased to a predetermined pressure. Space 20a and storage room 2
3, the connection hole 20b is closed. However, when the hydraulic oil leaks from the damper 12 or the like and the hydraulic pressure on the damper 12 side decreases, the pressure of the storage chamber 23 causes the valve body 19a to resist the urging force of the spring 19b, thereby causing the connection hole 20b.
Is moved in a direction away from the passage opening. Therefore, the bypass space 20a communicates with the storage chamber 23 through the connection hole 20b, and the space 20a is kept in contact with the valve body 19a by the oil pressure on the damper 12 side until the valve body 19a contacts the passage opening of the connection hole 20b.
Hydraulic oil is supplied from the storage chamber 23.

In the thus constructed forklift 1, as shown in FIG. 1, the electromagnetic solenoid 18 of the shut-off valve 13 is not excited when stopped, so that the first passage P1 and the third passage The passage P3 is shut off. That is, the damper 12 is in the locked state.

When the forklift 1 travels, the electromagnetic solenoid 18 is excited, and the shutoff valve 13 is switched so that the first passage P1 and the third passage P3 are in communication. That is, the damper 12 is switched from the locked state to the unlocked state, and the rear axle 11 to which the rear wheel 8 is connected is in a state capable of swinging with respect to the body frame 1a. In this state, the force acting on the rear wheel 8 is
2 and the traveling of the forklift 1 becomes stable.

Here, for example, when an excessive centrifugal force is applied to the forklift 1, the lift 1 cannot turn in a stable state if the damper 12 is unlocked. When the damper 12 needs to be locked in such a case or the like, fixed control is performed by the controller C, and the shut-off valve 1 is controlled.
The third excitation solenoid 18 is switched from the excited state to the non-excited state.

Then, the first passage P1 and the third passage P3 are shut off by the shutoff valve 13, and the damper 12
Is locked. Therefore, since the rear axle 11 is fixed to the vehicle body frame 1a, the forklift 1 can turn in a stable state.

As described above, when the hydraulic oil leaks and the oil pressure on the damper 12 decreases, the hydraulic oil is supplied from the accumulator 22 via the check valve 19 to the damper 12. Therefore, the first and second chambers R1,
Since R2 and each of the passages P1 to P3 are always filled with an appropriate amount of hydraulic oil, the hydraulic pressure of the hydraulic oil is kept constant, and the locking effect of the damper 12 is not reduced.

The shut-off valve 13 is normally of a so-called normally closed type which shuts off the first passage P1 and the third passage P3. This is because when the electric system of the forklift 1 fails, the rear axle 11
Is fixed to the body frame 1a.
This is because the running stability at the time of turning does not decrease. However, when the damper 12 is forced to move to repair the failed forklift 1 or the like, it may be difficult to travel if the damper 12 is in the locked state. In this case, the manual valve 21 is operated to operate the bypass passage P4. When the damper 12 is switched to the unlocked state, the lift 1
Can be in a runnable state.

As described above, according to the present embodiment,
It has the following features. (1) Accumulator 22, second and third passages P2, P
3, a check valve 19 is interposed. Therefore, the backflow from the damper 12 side to the accumulator 22 is prevented, and when the oil pressure on the damper 12 side decreases, the check valve 19 from the storage chamber 23 which has been increased to a predetermined pressure.
The hydraulic fluid is replenished to the second and third passages P2 and P3 via, so that the hydraulic fluid can always be filled with an appropriate amount,
The lock effect of the damper 12 is not reduced.

(2) The shut-off valve 13 is usually
A so-called normally closed type that shuts off the passage P1 and the third passage P3 is used. A bypass passage P4 is connected between the first and second chambers R1 and R2 of the damper 12, and a manual valve 21 is provided in the passage P4. Therefore, when the electric system of the forklift 1 breaks down, the rear axle 11 is fixed to the body frame 1a, so that the running stability of the lift 1 during turning does not decrease. In addition, when the vehicle is forced to move to repair the failed forklift 1 or the like, it may be difficult to travel if the damper 12 is in the locked state. In this case, the manual valve 21 is operated to move the bypass passage P4. By setting the communication state, and switching the damper 12 to the unlocked state, the lift 1 can be made to be able to travel.

(3) Each of the passages P1 to P3 is provided with a damper 12
The shut-off valve 13, the check valve 19, the accumulator 22 and the like are formed on the body 12a.
2a is integrally assembled. Therefore, each valve 1
As compared with the case where the accumulators 22 and the like are assembled separately from the damper 12, there is no need for a support member for supporting the valves 13, 19 and the accumulators 22, so that the cost of the forklift 1 and the number of assembling steps can be reduced. Can contribute.

(4) The damper 12 is a double-acting hydraulic cylinder. Therefore, in a forklift using a single-acting damper, the body frame 1a and the rear axle 11
Although two dampers are required between the two, the use of the double-acting damper 12 allows only one damper to be connected between the body frame 1a and the rear axle 11, thereby reducing the cost of the forklift 1. Also, it can contribute to a reduction in the number of assembling steps.

The embodiment is not limited to the above, but may be modified as follows. ○ In the above embodiment, the check valve 19 is used.
As long as backflow from the damper 12 side to the accumulator 22 side can be prevented, another type of valve may be used instead.

In the above embodiment, the passages P1 to P3
Are formed on the body 12a of the damper 12, and the shut-off valve 13, the check valve 19, and the accumulator 22
And the like are integrally attached to the body 12a.
1 to P3, valves 13 and 19, and accumulator 22
May be provided separately from the damper 12 on the vehicle body frame 1a or the like.

In the above embodiment, the double-acting damper 12 is used. However, a single-acting damper, a multi-stage damper, or the like may be used. As described above, each embodiment of the present invention has been described, but regarding technical ideas other than the claims that can be grasped from each of the above embodiments,
These effects are described below.

(A) The hydraulic circuit for an industrial vehicle according to any one of claims 1 to 3, wherein the damper is a double-acting type. With this configuration, an industrial vehicle using a single-acting damper requires two dampers between the body frame and the axle, but using a double-acting damper allows the body frame and the axle to be used. And only one damper is required, which can contribute to a reduction in the cost of the industrial vehicle and a reduction in the number of assembling steps.

[0048]

According to the first aspect of the present invention, even when the electromagnetic control valve that shuts off the passage for supplying and discharging the hydraulic oil to and from the damper in the non-energized state is used, the vehicle can travel with the damper locked. When it is difficult, it is possible to provide a hydraulic circuit for an industrial vehicle that can manually switch the passage between a shut-off state and a communication state regardless of the control valve to enable travel.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described above, it is possible to provide a hydraulic circuit for an industrial vehicle that does not perform a work of filling the hydraulic oil even if the hydraulic oil leaks and that does not reduce the effect of locking the axle to the body frame. .

According to the third aspect of the present invention, in addition to the effects of the first and second aspects of the present invention, a hydraulic circuit for an industrial vehicle that can contribute to a reduction in the cost of the industrial vehicle and a reduction in the number of assembling steps is provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a mechanism for fixing a rear axle according to an embodiment.

FIG. 2 is a side view showing the forklift.

FIG. 3 is a sectional view showing a damper.

FIG. 4 is a sectional view of a main part showing a damper.

FIG. 5 is a front view showing a damper.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 1a ... Body frame, 11 ... Rear axle which comprises an axle, 12 ... Hydraulic damper, 12a ... Body, 13 ... Shut-off valve as an electromagnetic control valve, 19 ... Backflow prevention means Check valve, 21: manual valve as a manually operated valve, 22: accumulator as supply means, C: controller as fixed control means, P1 to P3: first to third passages.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaya Hyodo 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Takataka Muto 2-4-2 Hamamatsucho, Minato-ku, Tokyo No. 1 World Trade Center Building Kayaba Kogyo Co., Ltd. (72) Inventor Teruyuki Shioya 2-4-1, Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Kogyo Co., Ltd.

Claims (3)

[Claims] 1. An industrial vehicle having an axle vertically swingably supported with respect to a body frame, disposed between the body frame and the axle, and supplying and discharging hydraulic oil in accordance with the swing of the axle. A damper and a passage for flowing hydraulic oil supplied / discharged from the damper when not energized is switched to a blocked state to lock the damper, and when energized, the passage is switched to a communicating state and the damper is unlocked. An electromagnetic control valve, fixed control means for controlling the electromagnetic control valve to switch to a communication state or a shut-off state, and manually closing the passage irrespective of an operation of switching the electromagnetic control valve to a shut-off state A hydraulic circuit for an industrial vehicle, comprising: a manually operated valve that switches between a state and a communication state. 2. A supply means connected to a passage for flowing the hydraulic oil supplied and discharged from the damper, the supply means for supplying the hydraulic oil to keep the hydraulic pressure of the hydraulic oil flowing through the passage constant, and the supply means The hydraulic circuit for an industrial vehicle according to claim 1, further comprising: a backflow prevention unit provided between the passage and the passage to prevent backflow of hydraulic oil from the passage to the supply unit. 3. The industrial system according to claim 2, wherein at least one of the electromagnetic control valve, the manually operated valve, the supply unit, and the backflow prevention unit is integrally assembled to the body of the damper. Vehicle hydraulic circuit.