JPH1024822A - Brake controller for traveling vehicle and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To brake rear wheels as strongly as the front wheels in working of excavation, loading, or the like and work at the stable state by providing a rear wheel brake booster means which feeds high pressure oil for being fed to a front wheel brake as a pressure oil for a rear wheel brake during working. SOLUTION: When a brake pedal 25 is stepped during the the traveling of a vehicle, a rear wheel brake valve 12 is switched from A to B position a pressure oil in an accumulator 5b is fed to a rear wheel oil pressure booster 18 and a rear wheel brake caliper 20 is driven by the generated pressure oil. The oil pressure boosted via a booster valve 14 is fed to a rear wheel oil pressure booster 17 so that the front wheel brake caliper 19 is driven. The front wheel braking force thus becomes larger than the rear wheel braking force so that the vehicle can be braked without any rear wheel lock. On the other hand, as for braking during working, a brake block valve 15 is switched from G to H position and the pressure oil is simultaneously fed to the front wheel and rear wheel oil pressure boosters 17, 18 respectively so that the front and rear wheels can be braked by the same braking force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a traveling brake of an industrial vehicle and a control method thereof, and more particularly to a control device for an industrial vehicle that performs braking during operation of the industrial vehicle using the brake during traveling of the industrial vehicle. The present invention relates to a traveling brake hydraulic control device and a control method thereof.

[0002]

2. Description of the Related Art When a full brake is applied during driving, the downward load on the front wheels increases, but the downward load on the rear wheels decreases. Therefore, the rear wheels are locked by the braking force of the same magnitude on the front and rear wheels. Easier to do. When the rear wheels are locked, not only does the braking force of the entire vehicle decrease, but also the vehicle easily spins, which is a problem in terms of safety. In order to solve this problem, for example, Japanese Patent Publication No. 2-1
No. 704 publication. According to the publication, a hydraulic pressure lower than the hydraulic pressure of the front wheel brake is supplied as the hydraulic pressure of the rear wheel brake, so that the braking force of the rear wheel is made smaller than that of the front wheel.

[0003]

However, in order to operate the vehicle in a stable state during the operation, the rear wheels are required to have a large braking force as in the case of the front wheels. Therefore, the technique disclosed in Japanese Patent Publication No. 2-1704 has a problem in that when a large load is applied to the work equipment during operation, the vehicle moves and excavation cannot be performed. Also, in vehicles with an upper revolving structure, when working on the rear wheel side and the front wheels rise, if the rear wheels alone support the load on the work equipment, the braking force on the rear wheels will be insufficient and the vehicle will become unstable Problem.

Therefore, the present invention has been made in view of the above-mentioned problem, and even if braking is performed with full brakes during high-speed traveling, the rear wheels can be safely braked without being locked.
It is an object of the present invention to provide a control device for a traveling brake of an industrial vehicle and a control method thereof, in which a rear wheel is also strongly braked by a brake lock operation in the same manner as a front wheel, so that a stable operation can be performed.

[0005]

Means for Solving the Problems and Functions / Effects In order to achieve the above object, in a first invention of a control device for a traveling brake of an industrial vehicle according to the present invention, the vehicle is stopped and excavation is performed by a working machine mounted on a vehicle. In a traveling brake control device for an industrial vehicle, which performs a work such as loading, a front wheel brake having a strong braking force and a rear wheel brake having a weak braking force, the traveling brake control device of an industrial vehicle brakes the vehicle during traveling and work. The rear wheel brake valve which reduces the pressure oil of the pressure source according to the pressure supplied to the rear wheel brake and operates in conjunction with the rear wheel brake valve, and supplies the front wheel with a pressure oil higher than the pressure supplied to the rear wheel brake. It is characterized by comprising a front-wheel brake valve to be supplied to the brake, and a rear-wheel brake pressurizing means for supplying high pressure oil to be supplied to the front wheel brake as pressure oil for the rear wheel brake during operation. . According to the above configuration, when the operator depresses the brake pedal, the brake valve for the front wheel and the brake valve for the rear wheel are moved according to the movement amount (depression amount),
The pressure from the pressure source is reduced and supplied to each of the front wheel brake and the rear wheel brake. At this time, in normal traveling, a higher pressure is output for the front wheel brake than for the rear wheel brake, and the front wheel brake has a strong braking force. Further, in the present invention, at the time of work, the pressure at this time is made equal to the pressure of the pressure oil supplied to the front wheel brake by the rear wheel brake pressure increasing means. As a result, when the brake pedal is depressed during traveling, a strong braking force is generated on the front wheels, a weak braking force is generated on the rear wheels, and the same strong braking force is generated on the rear wheels as the front wheels during work. In addition, the rear wheel and the front wheel can maintain the reaction force during the work without moving, and the vehicle can work in a stable state, the excavating force of the work machine increases, and the amount of work increases.

According to a second aspect of the present invention, a rear wheel brake booster includes a pipe connecting a front wheel brake valve and a front wheel brake circuit, and a rear wheel brake. A rear wheel brake first booster valve disposed between the valve and a pipe connecting the rear wheel brake circuit;
The brake valve for the rear wheel and the rear wheel brake circuit are disposed in a pipe and connected to the rear wheel brake first booster valve;
And a shuttle valve for selecting either one of the front wheel brake valve and the rear wheel brake valve pressure oil. The brake oil pressure command causes the pressure oil of the front wheel brake valve to pass through the first pressure boost valve and the shuttle valve to the rear wheel brake valve. It is characterized in that it is supplied as pressure oil for the brake circuit. With the above configuration, during operation, high pressure oil generated by the front wheel brake valve is supplied as pressure oil to the rear wheel brake via the first booster valve and the shuttle valve, and high pressure oil generated by the front wheel brake valve is provided. Shuts off low pressure from the rear wheel brake valve by the shuttle valve. Thus, the high pressure oil generated by the front wheel brake valve reliably acts on the rear wheels with a simple configuration, and increases the braking force of the rear wheels.

According to a third aspect of the present invention, a rear-wheel brake booster is disposed in a pipe connecting a rear-wheel brake valve and a rear-wheel brake circuit. And a rear wheel brake second booster valve connected to a pipe connecting the front wheel brake valve and the front wheel brake circuit. The brake booster command causes the pressure of the front wheel brake valve to pass through the rear wheel brake second booster valve. The oil is supplied as pressure oil for the rear wheel brake circuit. With the above configuration, similarly to the second invention, the high pressure oil generated by the front wheel brake valve acts on the rear wheel brake via the second pressure increasing valve. Thus, with a configuration simpler than that of the second aspect of the present invention, it acts on the rear wheel without fail, and increases the braking force of the rear wheel.

According to a fourth aspect of the present invention, there is provided a traveling brake control device for an industrial vehicle mainly comprising one of the first to third aspects, wherein the transmission of the operating force from the brake pedal to the rear wheel brake valve is performed by the brake pedal. It is characterized by a pilot pressure of an intensity corresponding to the operation amount or a link connecting a brake pedal and a brake valve for a rear wheel. With the above configuration, in the case of pilot pressure, the master cylinder attached to the brake pedal and the brake valve for the rear wheel can be connected by piping, which simplifies the configuration and increases the operation of the small brake pedal by using boosting. A large operating force can be applied to the rear wheel brake valve by force. In particular, at the stroke end of the operation amount of the brake pedal at the time of work, the operating force is lightened and the effect is great for an industrial vehicle that often requires a large braking force of the rear wheel brake. In the case of a link, since the brake valve is mechanically connected to the brake pedal, the operation of the brake pedal is reliably transmitted to the brake valve, and for industrial vehicles that frequently apply braking force, Responsiveness and drivability are also improved.

According to a fifth aspect of the present invention, there is provided a traveling brake control device for an industrial vehicle mainly comprising one of the first to fourth aspects of the invention, wherein the front wheel brake valve and the rear wheel brake valve are operated by a brake lock means during operation. Lock while operating. Accordingly, at the time of work, the work can be performed while the braking force of the rear wheel is reliably increased, the vehicle can be stably worked without moving during the work, the workability is improved, and the work amount is increased.

A sixth embodiment of the control device for a traveling brake of an industrial vehicle.
In the invention, the vehicle is stopped and excavated by the work machine mounted on the vehicle,
In a traveling brake control device for an industrial vehicle that performs operations such as loading and uses a front wheel brake having a strong braking force and a rear wheel brake having a weak braking force to brake the vehicle at the time of traveling and at the time of operation, a strong force corresponding to an operation amount is provided. And a variable pressure reducing valve for the rear wheel brake, which operates in response to the pilot pressure and reduces the pressure oil of the pressure source according to the pilot pressure and supplies it to the rear wheel brake. A front wheel brake valve that operates in conjunction with a rear wheel brake variable pressure reducing valve and supplies pressure oil higher than the pressure supplied to the rear wheel brake to the front wheel brake. At the time of work, the pressure oil of the pressure source is reduced to the same pressure as the pressure oil supplied to the front wheel brake by the low pressure oil supplied to the rear wheel brake. With the above configuration, during operation, the rear wheel brake receives the same pressure as the pressure oil supplied to the front wheel brake by the rear wheel brake variable pressure reducing valve. This allows
As in the first invention, during traveling, a strong braking force is generated on the front wheels and a weak braking force is generated on the rear wheels, and during work, the same strong braking force is generated on the rear wheels as on the front wheels. The rear wheel and the front wheel can maintain the reaction force at the time of work without moving the vehicle, and the vehicle can work in a stable state. The excavating force of the work machine increases, and the amount of work increases.

According to a seventh aspect of the present invention, there is provided a control device for a traveling brake of an industrial vehicle, which is mainly composed of a brake locking means for locking a front wheel brake valve and a rear wheel brake variable pressure reducing valve while operating. It is characterized by becoming. With the above configuration, during operation, the front wheel brake valve and the rear wheel brake variable pressure reducing valve are locked while being operated by the brake lock means. As a result, as in the fourth aspect, at the time of work, the work can be performed while the braking force of the rear wheel is reliably increased, and the vehicle can be stably worked without moving during the work, thereby improving workability. , The amount of work increases.

A control device for a traveling brake of an industrial vehicle mainly comprising one of the first invention, the second invention, the third invention or the sixth invention, and the fifth invention or the seventh invention. 8 In the invention, a shift lever position sensor attached to a shift lever from which stop and traveling speeds are selected,
Stop, excavation by a work machine mounted on the vehicle, loading, etc., or a mode selection sensor attached to the mode selection means to select traveling, a vehicle speed sensor to detect the speed of the vehicle, comprising a A rear wheel brake booster, a rear wheel brake first booster,
It is characterized by comprising either a rear wheel brake second pressure increasing valve or a rear wheel brake variable pressure reducing valve, a brake locking means, and a control means for outputting a 0 command. According to the above configuration, when the operation mode is selected by the mode selection means and the vehicle stops during the operation, the rear wheel brake receives the same pressure as the pressure oil supplied to the front wheel brake. Thereby, since the rear wheel brake automatically receives the same pressure as the pressure oil supplied to the front wheel brake during work, it is not necessary to work with the rear wheel brake kept low.

[0013] A control device for a traveling brake of an industrial vehicle mainly comprising one of the first invention, the second invention, the third invention or the sixth invention, and the fifth invention or the seventh invention. According to the ninth aspect, the brake lock switch outputs a command to lock the brake.
Any of the rear wheel brake pressure increasing means, the rear wheel brake first pressure increasing valve, the rear wheel brake second pressure increasing valve, or the rear wheel brake variable pressure reducing valve, and the control means for outputting a command to the brake locking means. It is characterized by becoming. With the above configuration, the brake lock switch causes the rear wheel brake to receive the same pressure as the pressure oil supplied to the front wheel brake. Thus, with a simpler configuration than the seventh invention,
During operation, the rear wheel brake and the front wheel brake can be automatically set to the same strength. Further, the structure is simplified, the reliability is improved, and the cost is reduced.

According to a first aspect of the present invention, there is provided a method for controlling a traveling brake of an industrial vehicle, wherein the vehicle is stopped by a working machine mounted on the vehicle to perform operations such as digging and loading, and a front wheel brake having a strong braking force and a weak brake. In a traveling brake control method for an industrial vehicle in which a vehicle is braked at the time of traveling and working by a rear wheel brake having power, a pressure of a front wheel side brake is set as a pressure of a rear wheel side brake by a brake pressure increase command at a time of working. Is characterized by increasing the braking force. According to the above method, at the time of work, the braking force of the rear wheel brake is increased by the booster. Thereby, an operation and an effect similar to those of the first, second, and third inventions of the device can be obtained.

A second control method for a traveling brake of an industrial vehicle
According to the invention, the stop and traveling speed are selected by the shift lever, and the vehicle is stopped by the work machine mounted on the vehicle to perform work such as excavation and loading, and the vehicle further includes a mode selection means for selecting traveling and work, and includes a front wheel brake. And in a traveling brake control method for an industrial vehicle in which the vehicle is braked at the time of traveling and work by a rear wheel brake, a signal from a mode selection sensor, a shift lever position sensor and a vehicle speed sensor, or a brake locking means for locking the brake,
The front wheel brake and the rear wheel brake are braked and locked. According to the above method, the same operation and effect as those of the eighth and ninth inventions of the device can be obtained.

A second method of controlling a traveling brake of an industrial vehicle.
A third aspect of the invention is characterized in that when the mode selection is a work mode, or when the brake locking means is turned on (ON), the braking force of the rear wheel brake is increased to perform braking and lock. According to the above-described method, the front wheel brake and the rear wheel brake have the same braking force and are locked to the same braking force only by turning on (turning on) the work mode or the brake locking means. This achieves the same effects as the fifth and seventh aspects of the device.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic control device for a traveling brake of an industrial vehicle and a control method thereof according to the present invention will be described below with reference to the drawings. FIG. 6 shows an example of an industrial vehicle 51 in which the traveling brake hydraulic control device of the present invention is used. The industrial vehicle 01 includes a lower traveling body 52 and an upper revolving body 53. The lower traveling body 52 has a front wheel 54 attached to the front and a rear wheel 55 attached rearward. Is provided with a working machine 56. The industrial vehicle 51 stops the vehicle, and performs work such as excavation and loading by a work machine 56 mounted on the vehicle. At this time, the front wheel 54
And the rear wheel 55 is provided with a traveling brake 19 to be described later,
The work is performed by braking the vehicle 20 so that the vehicle does not move. Further, such an industrial vehicle 51 is provided with a front wheel brake 19 having a strong braking force and a rear wheel brake 20 having a weak braking force, which will be described later, and a front wheel 54 and a rear wheel 55 are provided.

FIG. 1 is a circuit diagram of a hydraulic control device for a traveling brake of an industrial vehicle 51 according to a first embodiment. In FIG.
The engine 1 drives a hydraulic pump 2. The hydraulic oil sucked and discharged from the tank 3 by the hydraulic pump 2
Are branched into conduits 4a and 4b, each of which has an input port 11 for a front wheel brake valve 11 and a rear wheel brake valve 12.
a, 12a. The pipelines 4a and 4b are provided with accumulators 5a and 5b for accumulating the pressure oil and check valves 7a and 7b for preventing the pressure oil accumulated in the accumulators 5a and 5b from flowing back to the hydraulic pump 2. ing. The accumulators 5a, 5 are provided in the pipelines 4a, 4b.
When the oil pressure in b becomes higher than the set value,
There is provided a relief valve 9 for discharging to the air. The front wheel brake valve 11 has an input port 11a, a tank port 11b, and an output port 11c.
a, tank port 110 to tank 3, output port 1
1c is a hydraulic booster 1 for front wheels through conduits 21 and 21a.
7 is connected to the input terminal 17a. The rear wheel brake valve 12 has an input port 12a, a tank port 12b, and an output port 12c, and the input port 12a is connected to the pipeline 4b.
The tank port 12b is connected to the tank 3 and the output port 12c is connected to the first input port 13a of the shuttle valve 13 through the pipe 22.
It is connected to the. Shuttle valve 13 is the first input port 1
3a, a second input port 13b, and an output port 13c. The first input port 13a is connected to an output port 12c of the rear wheel brake valve 12 through a pipe 22, and the output port 13c is connected to a rear wheel hydraulic booster through a pipe 22a. 18 input terminals 18
a. An output end 17 b of the front wheel hydraulic booster 17 is connected to a front wheel brake caliper 19 through a conduit 23. The output end 18b of the rear wheel hydraulic booster 18 is connected to the rear wheel brake caliper 20 through a conduit 24.
It is connected to the.

The rear wheel brake valve 12 has a spring 12d.
At the position A, and the first pressure receiving portion 12e or the second pressure receiving portion 12e.
The pilot pressure switching type two-position valve switches to the position B when the pilot pressure is input to the pressure receiving portion 12f. The first pressure receiving portion 12e has an input end 26b connected to an output end 26a of the master cylinder 26 connected to the brake pedal 25 by a pipe 27.
When the brake pedal 25 is depressed, a pilot pressure corresponding to the depression force (operation amount) is input to the first pressure receiving portion 12e, and the main spool of the rear wheel brake valve 12 moves. Has become. The second pressure receiving portion 12f is connected to the output port 15c of the brake lock valve 15 through a pipe 28,
Is switched from the G position to the H position, the second pressure receiving portion 1
The pilot pressure is input to 2f.

The rear wheel brake valve 12 is provided with a pressure reducing valve 32 between the input port 12a and the output port 12c at the position B, and the output pressure is changed according to the amount of movement of the main spool with respect to the input pressure Pa. Pr is reduced from 0 to the maximum P2.

The front wheel brake valve 11 includes a spring 12
Although it is connected to the rear wheel brake valve 12 in tandem via d, it is normally held at the C position by a spring 11d. At the time of the brake operation, when the pilot pressure is input to the first pressure receiving portion 12e or the second pressure receiving portion 12f of the rear wheel brake valve 12, it is operated in exactly the same manner as the rear wheel brake valve 12, and is switched to the D position. The front-wheel brake valve 11 has an input port 11a and an output port 11c in the D position.
The pressure reducing valve 31 is provided between the main pressure and the output pressure Pf from 0 to the maximum P with respect to the input pressure Pa in accordance with the amount of movement of the main spool (= the amount of movement of the main spool of the rear wheel brake valve 12).
The pressure has been reduced to 1. In this case, P1> P2 is set. In the above embodiment, the front wheel brake valve 11 is connected to the rear wheel brake valve 12, but may be separately connected to the master cylinder 26 to receive pilot pressure and operate.

Input end 17a of front wheel hydraulic booster 17
And a rear wheel brake first pressure-increasing valve 14 via a shuttle valve 13 between the rear wheel hydraulic booster 18 and the input end 18a of the rear wheel hydraulic booster 18. The rear wheel brake first pressure increasing valve 14 has an input port 14a, a tank port 14b, and an output port 14c. The input port 14a is connected to the output port 11c of the front wheel brake valve 11 through the pipe 21 and the tank port 14b is connected to the tank 3. , The output port 14c is connected to the second input port 13b of the shuttle valve 13 through the line 22b. The rear wheel brake first pressure increasing valve 14 has a spring 14e.
The electromagnetic switch type two-position valve that is held at the E position and switches to the F position when the receiving unit 14d is energized, and is a brake lock switch 41 (hereinafter, referred to as a brake lock sw41).
Is turned on, a current is supplied from the power supply 47 to the receiving unit 14d.

The brake lock valve 15 is connected to the input port 15
a, a tank port 15b, and an output port 15c. The input port 15a is connected to the hydraulic pressure source 2a, the tank port 15b is connected to the tank 3, and the output port 15c is connected to the second pressure receiving portion 12f of the rear wheel brake valve 12 through the conduit 28. It is connected to the.
The brake lock valve 15 is an electromagnetic switching type two-position valve that is held at the G position by a spring 15e and switches to the H position when the receiving unit 15d is energized.
By performing the N operation, a current is supplied from the power supply 47 to the receiving unit 15d.

The operation unit 45 of the vehicle is provided with a mode changeover switch 42 (hereinafter, referred to as mode changeover sw42) for switching between the traveling mode and the work mode, and a shifter switch 43 (hereinafter, referred to as shifter sw43) for switching the vehicle speed. , Sw are input to the T / M controller 44.

Next, the operation of FIG. 1 will be described. First, braking during traveling of the vehicle will be described. When the brake pedal 25 is depressed during traveling of the vehicle, the input end 26a of the master cylinder 26 moves, and the output end 26b of the master cylinder 26 moves.
, And acts as pilot pressure on the first pressure receiving portion 12e of the rear wheel brake valve 12 through the pipe line 27 to switch the rear wheel brake valve 12 from the position A to the position B. The pressure oil accumulated in the accumulator 5b (pressure =
Pa) is the pipe 4b, the rear wheel brake valve 12, the pipe 22,
It flows to the input end 18a of the rear wheel hydraulic booster 18 through the shuttle valve 13 and the pipeline 22a. At this time, the input terminal 18a
Changes from 0 to the maximum P2 depending on the depression force of the brake pedal 25. Due to the boosting action of the hydraulic booster 18 (magnification = α), a hydraulic pressure ranging from 0 to a maximum α × P2 is generated at the output end 18b. And the rear wheel is braked. On the other hand, front wheel brake valve 11
Is switched from the position C to the position D because the gear is linked with the rear wheel brake valve 12. Then, the pressure oil (pressure = Pa) accumulated in the accumulator 5a flows to the input end 17a of the front wheel hydraulic booster 17 through the pipeline 4a, the front wheel brake valve 11, and the pipelines 21 and 21a. At this time, the oil pressure acting on the input terminal 17a changes from 0 to the maximum P1. Due to the boosting action of the hydraulic booster 17 (magnification = α), a hydraulic pressure ranging from 0 to a maximum α × P1 is generated at the output terminal 17b, and this hydraulic oil is supplied to the front wheel brake caliper 19 through the pipeline 23. The vehicle is guided and the front wheels are braked. Here, the maximum hydraulic pressure P1 acting on the input terminal 17a of the front wheel hydraulic booster 17 is equal to the input terminal 18 of the rear wheel hydraulic booster 18.
a larger than the maximum hydraulic pressure P2 acting on the normal pressure a (normally P1 =
1.5 × P2), the front wheel braking force is greater than the rear wheel braking force, and the well-balanced and safe braking of the entire vehicle body can be performed without locking the rear wheels.

Next, braking during operation will be described. When the brake block sw41 is turned on, power is supplied to the receiving portion 15d of the brake block valve 15, and the brake block valve 15 switches from the G position to the H position. Then, the pressure oil of the hydraulic pressure source 2a acts on the second receiving portion 12f of the rear wheel brake valve 12 through the pipeline 28, and the rear wheel brake valve 12
The position is switched to the position B. At the same time, the front wheel brake valve 11 switches from the C position to the D position. Also, the power is supplied to the receiving portion 14d of the rear wheel brake first pressure increasing valve 14, and the rear wheel brake first pressure increasing valve 14 switches from the E position to the F position. As a result, the pressure oil (pressure = Pa) accumulated in the accumulator 5a flows through the pipeline 4a, the front wheel brake valve 11, and the pipelines 21 and 21a to the input end 17a of the front wheel hydraulic booster 17, and at the same time, through the pipeline. Rear wheel brake first from 21
Pressure increasing valve 14, line 22b, shuttle valve 13, line 22a
To the input end 18a of the rear wheel hydraulic booster 18. At this time, the input end 17a of the hydraulic booster 17 for the front wheels,
The same oil pressure that changes from 0 to the maximum P1 acts on the input end 18a of the rear wheel hydraulic booster 18. This hydraulic pressure is boosted by hydraulic boosters 17 and 18 (magnification =
α), the output terminals 17b, 1
8b, a hydraulic pressure from 0 to a maximum α × P1 is generated, and this hydraulic pressure is transmitted through the lines 23 and 24 to the brake calipers 19,
20 and the front and rear wheels are braked with the same braking force. Therefore, the vehicle can work in a stable state.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram of a traveling brake hydraulic control device for an industrial vehicle 51 according to a second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Although the shuttle valve 13 is used in the first embodiment of FIG. 1, the shuttle valve 13 is omitted in the second embodiment of FIG. 2, and the rear wheel brake first pressure increasing valve 14 is replaced with the rear wheel brake second pressure increasing valve. 1
4B. The rear wheel brake second pressure increasing valve 14B has a first input port 14f and a second input port 14f.
g, an output port 14h, and a first input port 14f is connected to an output port 1 of the front wheel brake valve 11 through a conduit 21.
1c, the second input port 14g is connected to the output port 12c of the rear wheel brake valve 12 through the conduit 22 and is connected to the output port 1c.
Reference numeral 4h is connected to an input end 18a of the rear wheel hydraulic booster 18 through a conduit 22a. The rear-wheel brake second pressure increasing valve 14B is held at the position I by the spring 14i, and is switched to the position J when the receiving portion 14j is energized. A current is supplied to the section 14j.

The operation of FIG. 2 will be described. With regard to braking during traveling of the vehicle, the pressure oil from the rear wheel brake valve 12 is supplied to the second input port 14 of the rear wheel brake second pressure increasing valve 14B.
g, the output port 14h, and the pipe 22a, and are the same as those of the first embodiment except that they flow to the input end 18a of the hydraulic booster 18 for the rear wheel.
This is exactly the same as the embodiment. With regard to the braking during the operation of the vehicle, the ON operation of the brake lock sw41 switches the rear wheel brake second pressure increasing valve 14B from the I position to the J position, and the pressure oil from the front wheel brake valve 11 causes the rear wheel brake second First input port 14f, output port 1 of booster valve 14B
4h, after passing through the pipeline 22a, the rear wheel hydraulic booster 18
This embodiment is the same as the first embodiment except that it flows to the input end 18a, and the braking of the front wheels and the rear wheels is exactly the same as the first embodiment.

According to the second embodiment, in addition to the effects of the first embodiment, the structure is simplified and the reliability is improved.
Costs are also lower.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a circuit diagram of a traveling brake hydraulic control device for an industrial vehicle 51 according to a third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the first embodiment of FIG. 1, the shuttle valve 13 and the rear wheel brake first boost valve 14 are used. However, in the third embodiment of FIG. 3, the shuttle valve 13 and the rear wheel brake first boost valve 14 are omitted. The pressure oil from the front wheel brake valve 11 is supplied to the front wheel hydraulic booster 17.
The pressure oil from the rear wheel brake valve 12 is led to the input end 18a of the rear wheel hydraulic booster 18 and the pressure reducing valve 32 provided on the rear wheel brake valve 12 is changed to a variable pressure reducing valve. 32B. When no current is supplied to the receiving unit 32a, the variable pressure reducing valve 32B
In the same manner as the pressure reducing valve 32, the output pressure Pr of the rear wheel brake valve 12 depends on the amount of movement of the main spool with respect to the input pressure Pa.
Is reduced from 0 to the maximum P2. However, when the brake lock sw41 is turned on and the receiving unit 32a is energized, the output pressure Pr is reduced from 0 to the maximum P1 (the same as the front wheel).

The operation of FIG. 3 will be described. With respect to braking during traveling of the vehicle, the pressure oil from the front wheel brake valve 11 is applied to the input end 17a of the front wheel hydraulic booster 17 and the pressure oil from the rear wheel brake valve 12 is directly applied to the rear wheel hydraulic booster 18.
The first embodiment is the same as the first embodiment except that it flows to the input terminals 18a of the first embodiment, and the braking of the front wheels and the rear wheels is completely the same as the first embodiment. Regarding the braking during the operation of the vehicle, the ON operation of the brake lock sw41 energizes the receiving portion 32a of the variable pressure reducing valve 32B, and the variable pressure reducing valve 32B changes the output pressure Pr of the rear wheel brake valve 12 from 0 to the maximum P1. The decompression is reduced so that it is the same as the braking force of the front wheels. The first embodiment is the same as the first embodiment except that the pressure oil from the rear wheel brake valve 12 flows directly to the input end 18a of the rear wheel hydraulic booster 18.
The braking of the rear wheels is exactly the same as in the first embodiment.

According to the third embodiment, in addition to the effects of the first embodiment, the structure is further simplified, the reliability is improved, and the cost is reduced.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a circuit diagram of a traveling brake hydraulic control device for an industrial vehicle 51 according to a fourth embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the fourth embodiment of FIG. 4, the hydraulic pressures of the main circuit are all set to α times (α = multiplier of the hydraulic boosters 17 and 18) as in the first embodiment.
Front wheel hydraulic booster 17 and rear wheel hydraulic booster 18
Are omitted, and the pressure oil from the front wheel brake valve 11A and the rear wheel brake valve 12A is directly supplied to the brake calipers 19,2.
It has been brought to 0. That is, the relief valves 9A and 9B
Is the set pressure Pa of the relief valve 9 of the first embodiment.
It is set to α times. Brake valve for front wheel 11
The pressure reducing valve 31A provided at the position A moves the main spool with respect to the input pressure α × Pa (= the rear wheel brake valve 12A).
The output pressure Pf is reduced from 0 to a maximum α × P1 in accordance with the amount of movement of the main spool. The pressure reducing valve 32A provided in the rear wheel brake valve 12A reduces the output pressure Pr from 0 to a maximum α × P2 according to the amount of movement of the main spool with respect to the input pressure α × Pa. I have. The hydraulic pump 2A, the accumulators 5A, 5A
B, front wheel brake valves 11A and 12A, shuttle valve 13
A, the rear wheel brake first pressure increasing valve 14A is of a high pressure type, and its functions are the hydraulic pump 2, accumulators 5a and 5b, front wheel brake valve 11, rear wheel brake valve 12, shuttle valve 13 of the first embodiment. , Rear wheel brake first booster valve 1
4 and the description is omitted.

The operation of FIG. 4 is the same as that of FIG. 1 except that the pressure oil from the front wheel brake valve 11A and the rear wheel brake valve 12A are directly guided to the front wheel brake caliper 19 and the rear wheel brake caliper 20, respectively. The braking of the front and rear wheels is exactly the same as in the first embodiment.

According to the fourth embodiment, in addition to the effects of the first embodiment, the structure is simplified, the reliability is improved, and the cost is reduced.

A fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a circuit diagram of a traveling brake hydraulic control device for an industrial vehicle 51 according to a fifth embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. 5 of FIG.
In the embodiment, the brake lock sw41 is omitted in FIG. 1, and the work mode of the mode switching sw42 is such that when the brake lock is engaged and the shifter sw43 is in the neutral N, the receiving portion of the brake lock valve 15 15d and the receiving part 14d of the rear wheel brake first pressure increasing valve 14
The current is supplied from the T / M controller 44A as a brake lock command. In addition, when the work mode signal and the shifter N signal are input during traveling and the brakes are locked, sudden braking is applied and it is dangerous. Therefore, the vehicle speed is detected by the pickup 46, and the brake lock command is not issued unless the vehicle speed becomes zero. I have. Except for this, it is the same as the first embodiment, and the braking of the front wheels and the rear wheels is exactly the same as the first embodiment.

According to the fifth embodiment, in addition to the effects of the first embodiment, the complexity of the operation of the brake lock sw and forgetting to put the brake lock sw can be avoided, and the drivability is improved.

A sixth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a circuit diagram of the sixth embodiment. In the first to fifth embodiments, when the brake pedal 25 is depressed,
The pilot pressure according to the pedaling force is applied to the first pressure receiving portion 12e.
And the main spool of the brake valve 12 moves. However, in the sixth embodiment, the brake pedal 25A and the brake valve 12 are connected via the link 27A, and when the brake pedal 25A is depressed,
The main spool of the brake valve 12 moves according to the amount of stepping. The brake valve 12 reduces the output pressure Pr according to the pedaling amount.

According to the sixth embodiment, since the brake valve 12 is mechanically connected to the brake pedal 25A, the operation of the brake pedal 25A is reliably transmitted to the brake valve 12, and the responsiveness is improved. And drivability is also improved.

In the above embodiment, the hydraulic pressure is used as the pressure source of the main circuit. However, the pressure source of the main circuit may be pneumatic.
In this case, all the devices in the main circuit change from hydraulic to pneumatic, but the operation is the same as in the first embodiment, and the braking of the front and rear wheels is exactly the same as in the first embodiment. The circuit diagram of the seventh embodiment in which air pressure is used as the pressure source of the main circuit is omitted in FIG. 1 because all the components of the main circuit are changed from hydraulic to air.

According to such an example, in addition to the effect of the first embodiment, since the pressure medium is air, the handling of the equipment can be improved.
Easy maintenance.

In the above-mentioned second to seventh embodiments, it is natural that a brake oil pressure control device for a traveling vehicle can be constituted by appropriately combining the embodiments. However, the description is omitted here. I do.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a brake hydraulic control device for a traveling vehicle according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment.

FIG. 3 is a circuit diagram showing a third embodiment.

FIG. 4 is a circuit diagram showing a fourth embodiment.

FIG. 5 is a circuit diagram showing a fifth embodiment.

FIG. 6 is a circuit diagram showing a sixth embodiment.

FIG. 7 is a side view showing an example of an industrial vehicle 51 in which the traveling brake hydraulic control device of the present invention is used.

[Explanation of symbols]

1. Engine, 2, 2A ... Hydraulic pump, 5a, 5A, 6
a, 6A ... accumulator, 9a, 9b, 9A, 9B ...
Relief valve, 11, 11A ... Brake valve for front wheel, 12,
12A: rear wheel brake valve, 13, 13A: shuttle valve, 14, 14A: rear wheel brake first booster valve, 14B ...
Rear wheel brake second booster valve, 15 ... brake lock valve, 1
7 ... hydraulic booster for front wheel, 18 ... hydraulic booster for rear wheel,
19: front wheel caliper, 20: rear wheel caliper, 25: brake pedal, 26: master cylinder, 27A: link, 31, 31A, 32, 32A: pressure reducing valve, 32B: variable pressure reducing valve, 41: brake lock s
w, 42: mode switching sw, 43: shifter switching sw, 4
4, 44A T / M controller, 45 operation unit, 46
... Pickup, 51 ... Industrial vehicle, 52 ... Undercarriage,
53: upper revolving structure, 54: front wheel, 55: rear wheel.

Claims (12)

[Claims] The vehicle is stopped and digging, loading and the like are performed by a work machine mounted on the vehicle, and the vehicle is driven during traveling and work by a front wheel brake having a strong braking force and a rear wheel brake having a weak braking force. In a traveling brake control device for an industrial vehicle that brakes, it operates in conjunction with a rear-wheel brake valve and a rear-wheel brake valve that reduces the pressure oil from the pressure source according to the operation force of the brake pedal and supplies it to the rear-wheel brake. A front-wheel brake valve for supplying pressure oil higher than the pressure supplied to the rear wheel brake to the front wheel brake; and a rear wheel brake for supplying high pressure oil supplied to the front wheel brake as pressure oil for the rear wheel brake during operation. A travel brake control device for an industrial vehicle, comprising a booster. 2. The rear wheel brake booster is disposed between a pipe connecting the front wheel brake valve and the front wheel brake circuit and a pipe connecting the rear wheel brake valve and the rear wheel brake circuit. The first brake valve for the wheel brake, the brake valve for the rear wheel, and the pipe connecting the rear wheel brake circuit are connected and connected to the first brake valve for the rear wheel brake. And a shuttle valve for selecting either one of the pressure oils. The pressure oil of the front wheel brake valve is supplied as the pressure oil of the rear wheel brake circuit via the first pressure increase valve and the shuttle valve in response to a brake pressure increase command. The brake hydraulic pressure control device according to claim 1, wherein 3. The rear wheel brake booster is disposed on a pipe connecting the rear wheel brake valve and the rear wheel brake circuit, and connected to a pipe connecting the front wheel brake valve and the front wheel brake circuit. It is composed of a wheel brake second booster valve, and through a rear wheel brake second booster valve according to a brake booster command,
2. The brake hydraulic control device according to claim 1, wherein the pressure oil of the front wheel brake valve is supplied as the pressure oil of the rear wheel brake circuit. The transmission of the operating force from the brake pedal to the rear wheel brake valve is performed by a pilot pressure having a strength corresponding to the operation amount of the brake pedal, or a link connecting the brake pedal and the rear wheel brake valve. The brake hydraulic pressure control device according to any one of claims 1 to 3, wherein: 5. The industrial vehicle according to claim 1, further comprising brake lock means for locking the front wheel brake valve and the rear wheel brake valve while operating during operation. Travel brake control device. 6. The vehicle is stopped and digging, loading and the like are performed by a working machine mounted on the vehicle, and the vehicle is driven during running and working by a front wheel brake having a strong braking force and a rear wheel brake having a weak braking force. In a traveling brake control device for an industrial vehicle to be braked, a brake pedal that outputs a pilot pressure having a strength corresponding to an operation amount, and operates in response to the pilot pressure, and a pressure oil of a pressure source according to the strength of the pilot pressure. The variable pressure reducing valve for the rear wheel brake and the variable pressure reducing valve for the rear wheel brake are operated in conjunction with the variable pressure reducing valve for supplying to the rear wheel brake, and the pressure oil higher than the pressure supplied to the rear wheel brake is supplied to the front wheel brake. It consists of a front-wheel brake valve, and a variable pressure-reducing valve for rear-wheel brakes. During operation, low-pressure oil supplied to the rear-wheel brakes has the same strength as pressure oil supplied to the front-wheel brakes. Travel brake control apparatus for an industrial vehicle, characterized in that for reducing the pressure oil pressure source. 7. The traveling brake control device for an industrial vehicle according to claim 5, further comprising a brake lock means for locking the front wheel brake valve and the rear wheel brake variable pressure reducing valve while operating during operation. 8. A shift lever position sensor attached to a shift lever for selecting a stop and a traveling speed, and a mode selection for selecting an operation for stopping, excavating, loading, or the like with a working machine mounted on the vehicle, or for traveling. A mode selection sensor attached to the means, and a vehicle speed sensor for detecting the speed of the vehicle. During work, the rear wheel brake pressure increasing means, the rear wheel brake first pressure increasing valve, the rear wheel brake 3. A control means for outputting a command to one of a second pressure increasing valve and a variable pressure reducing valve for a rear wheel brake, and a brake locking means.
Claim 3 or 6, and claim 5 or 7
A travel brake control device for an industrial vehicle, comprising: 9. A brake lock switch for outputting a command to lock a brake, comprising a rear wheel brake booster, a rear wheel brake first booster valve, a rear wheel brake second booster valve, or a rear wheel brake during operation. And a control means for outputting a command to one of the variable pressure reducing valve for use and a brake lock means.
A traveling brake control device for an industrial vehicle, comprising: the driving brake control device according to claim 6; 10. A work machine mounted on a vehicle stops to perform work such as excavation and loading, and the vehicle is braked during traveling and work by a front wheel brake having a strong braking force and a rear wheel brake having a weak braking force. A brake hydraulic pressure control method comprising: increasing a braking force of a rear wheel brake by using a pressure of a front wheel side brake as a pressure of a rear wheel side brake in response to a brake pressure increase command during operation. 11. A mode selecting means for selecting a stop and a traveling speed by a shift lever, performing a work such as excavation and loading by stopping with a work machine mounted on a vehicle, and selecting a run and a work, In a traveling brake control method for an industrial vehicle in which a vehicle is braked at the time of traveling and work by a front wheel brake and a rear wheel brake, a signal from a mode selection sensor, a shift lever position sensor, and a vehicle speed sensor, or a brake locking means for locking a brake. A traveling brake control method for an industrial vehicle, comprising braking and locking a front wheel brake and a rear wheel brake. 12. The method according to claim 1, wherein the mode selection is a work mode or
12. The traveling brake control method for an industrial vehicle according to claim 11, wherein when the brake lock means is turned on, the braking force of the rear wheel brake is increased to perform braking and lock.