JP2023119733A - brake system - Google Patents

Abstract

To provide a brake system in which brake operation at manual operation can be compatible with brake control at automatic operation at low cost.SOLUTION: A brake system 1 comprises: a solenoid valve 9 which has a first open position 9a which communicates between a hydraulic fluid channel 21 where hydraulic fluid flows between a brake booster 6 and the solenoid valve 9 and a hydraulic fluid channel 23 where hydraulic fluid flows between the solenoid valve 9 and a brake wheel cylinder 4, and a second open position 9b which communicates between a hydraulic fluid channel 22 where hydraulic fluid flows to the solenoid valve 9 without passing through the brake booster 6 and the hydraulic fluid channel 23; and a brake control part 41 which controls, when braking a fork lift 2 during automatic operation of the fork lift 2, a solenoid operation part 24 of the solenoid valve 9 to switch a position of the solenoid valve 9 from the first open position 9a to the second open position 9b.SELECTED DRAWING: Figure 1

Description

The present invention relates to braking systems.

2. Description of the Related Art As a brake system used for industrial vehicles and the like, for example, the technology described in Patent Document 1 is known. The brake system described in Patent Document 1 includes a brake pedal, a vacuum booster and a master cylinder connected to the brake pedal via a rod, and a brake pedal and the vacuum booster arranged between the brake pedal and the vacuum booster. A first hydraulic cylinder having a coupled piston, a second hydraulic cylinder connected to the first hydraulic cylinder via hydraulic piping, a movable member pushing the piston of the second hydraulic cylinder, and driving the movable member and a motor. When the motor rotates while the driver is not stepping on the brake pedal, the movable member moves forward together with the piston of the second hydraulic cylinder, and hydraulic pressure is generated inside the second hydraulic cylinder, the hydraulic pipe and the first hydraulic cylinder. . Therefore, when the piston of the first hydraulic cylinder advances and pushes the rod, the vacuum booster is operated and brake hydraulic pressure is generated in the master cylinder.

JP-A-10-152028

However, in the conventional technology described above, in order to brake the industrial vehicle during automatic operation of the industrial vehicle, a dedicated first hydraulic cylinder, a second hydraulic cylinder, a movable member, and a motor are provided between the brake pedal and the vacuum booster. need to add. Therefore, the device for automatically braking the industrial vehicle becomes complicated, and the number of newly designed and manufactured products increases. Therefore, the cost for achieving compatibility between brake operation during manual operation and brake control during automatic operation increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a brake system capable of achieving both brake operation during manual driving and brake control during automatic driving at low cost.

One aspect of the present invention is a brake system for braking an industrial vehicle capable of automatic operation, comprising a brake pedal operated by a driver of the industrial vehicle, a hydraulic brake device that applies a braking force to the wheels of the industrial vehicle, and a hydraulic brake device. a booster that is placed between the oil pump and the hydraulic brake device to assist the driver in operating the brake pedal, and between the booster and the hydraulic brake device a first hydraulic fluid flow path through which hydraulic fluid flows between the solenoid valve and the solenoid valve; and a second hydraulic fluid flow path through which hydraulic fluid that does not pass through the booster flows toward the solenoid valve. a path, a third hydraulic fluid path through which hydraulic fluid flows between the solenoid valve and the hydraulic brake device, and a braking control section that controls the solenoid valve when the industrial vehicle is braked during automatic operation of the industrial vehicle. The solenoid valve has a first open position that communicates the first hydraulic fluid flow path with the third hydraulic fluid flow path and blocks communication between the second hydraulic fluid flow path and the third hydraulic fluid flow path, and a second operating fluid flow path. a second open position that communicates the oil flow path with the third hydraulic oil flow path and cuts off the first hydraulic oil flow path and the third hydraulic oil flow path; A solenoid operation part of a solenoid valve is controlled so that the position of the solenoid valve is switched from the first open position to the second open position when the industrial vehicle is braked during operation.

In such braking systems, the solenoid valve is normally in the first open position and manual operation of the industrial vehicle is implemented. When the brake pedal is operated by the driver during manual operation of the industrial vehicle, hydraulic fluid from the booster flows through the first hydraulic fluid flow path, the solenoid valve, and the third hydraulic fluid flow path to the hydraulic brake device. By being supplied, braking force is applied to the wheels by the hydraulic brake device. On the other hand, when braking the industrial vehicle during automatic operation of the industrial vehicle, the solenoid operating portion of the solenoid valve is controlled so that the position of the solenoid valve is switched from the first open position to the second open position. Therefore, hydraulic fluid that does not pass through the booster flows through the second hydraulic fluid flow path, the solenoid valve, and the third hydraulic fluid flow path and is supplied to the hydraulic brake device, so that the hydraulic brake device exerts a braking force on the wheels. Granted. Here, an existing electromagnetic switching valve can be used as the solenoid valve. Therefore, it is not necessary to newly design and manufacture a device for automatically braking the industrial vehicle. As a result, it is possible to achieve both brake operation during manual operation and brake control during automatic operation at low cost.

The brake system further includes a brake pressure detection unit that detects the pressure of hydraulic fluid supplied to the hydraulic brake device, and the brake control unit detects the position of the solenoid valve when the industrial vehicle is braked during automatic operation of the industrial vehicle. is switched from the first position to the second position and the pressure of hydraulic oil supplied to the hydraulic brake device is adjusted to the set pressure.

With such a configuration, when braking the industrial vehicle during automatic operation of the industrial vehicle, the pressure of the hydraulic oil supplied to the hydraulic brake device is adjusted to the set pressure. Therefore, it is possible to easily adjust the braking force applied to the wheels of the industrial vehicle.

The brake system is arranged between an accumulator that accumulates hydraulic oil discharged from the oil pump, and between the oil pump, the booster, and the accumulator, and the hydraulic oil from the oil pump is supplied to the accumulator according to the pressure of the accumulator. and a charge valve for switching between an oil passage through which the hydraulic oil from the oil pump is supplied to the booster, and the second hydraulic oil passage is a passage through which the hydraulic oil flows from the accumulator to the solenoid valve. may be

In such a configuration, when the industrial vehicle is braked during automatic operation of the industrial vehicle, the hydraulic fluid accumulated in the accumulator flows through the second hydraulic fluid flow path, the solenoid valve, and the third hydraulic fluid flow path to hydraulic brake. By being supplied to the device, a braking force is applied to the wheels by the hydraulic brake device. Therefore, the industrial vehicle can be effectively braked with a simple configuration during automatic operation of the industrial vehicle.

The brake system further includes an accumulator pressure detection unit that detects the pressure of the accumulator, and a pump control unit that controls a drive source that rotationally drives the oil pump based on the pressure of the accumulator during automatic operation of the industrial vehicle. The control unit may control the drive source to stop the rotation of the oil pump or decrease the rotation speed of the oil pump when the pressure of the accumulator is equal to or higher than the specified pressure.

In such a configuration, when the pressure of the accumulator is equal to or higher than the specified pressure, the rotation of the oil pump is stopped or the rotational speed of the oil pump is reduced. When the industrial vehicle is braked during automatic operation of the industrial vehicle, hydraulic oil is supplied from the accumulator to the hydraulic brake device, so the oil pump does not need to be operated all the time. Therefore, the energy consumption of the oil pump can be reduced by stopping the rotation of the oil pump or reducing the rotation speed of the oil pump. Therefore, the fuel efficiency of the industrial vehicle is improved, and the operating time of the industrial vehicle can be extended.

The brake system consists of a detection unit that detects whether the brake pedal is operated during automatic operation of industrial vehicles, and a state in which the solenoid valve is in the second open position. It may further include an automatic operation stop control unit that controls the solenoid operation unit so that the position of the solenoid valve is switched from the second open position to the first open position when the operation is detected.

In such a configuration, when the brake pedal is operated by the driver while the solenoid valve is in the second open position by braking the industrial vehicle during automatic operation of the industrial vehicle, the position of the solenoid valve is changed to the second position. The second open position is switched to the first open position, and the braking of the industrial vehicle by automatic operation is forcibly stopped. Therefore, braking force is applied to the wheels by supplying hydraulic fluid from the booster to the hydraulic brake device. In this way, when the brake pedal is operated during automatic operation of the industrial vehicle, automatic operation is switched to manual operation. Therefore, it is possible to prevent the brake control from being performed against the intention of the driver.

Advantageous Effects of Invention According to the present invention, it is possible to inexpensively achieve both brake operation during manual operation and brake control during automatic operation.

1 is a configuration diagram showing a brake system according to one embodiment of the present invention; FIG. 2 is a configuration diagram showing details of a solenoid valve and a system control system shown in FIG. 1; FIG. FIG. 3 is a flowchart showing a procedure of braking control processing executed by a braking control unit shown in FIG. 2; FIG. FIG. 3 is a flow chart showing a procedure of an automatic operation stop control process executed by an automatic operation stop control unit shown in FIG. 2; FIG. FIG. 3 is a flowchart showing a procedure of oil pump control processing executed by the pump controller shown in FIG. 2; FIG. FIG. 6 is a flow chart showing a modification of the procedure of the oil pump control process shown in FIG. 5; FIG. FIG. 2 is a configuration diagram showing a modified example of the brake system shown in FIG. 1;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

FIG. 1 is a configuration diagram showing a brake system according to one embodiment of the present invention. In FIG. 1, a brake system 1 of this embodiment is mounted on a forklift 2, which is one of industrial vehicles. The forklift 2 is an electric forklift capable of automatic operation.

A brake system 1 is a system for braking the forklift 2 . A brake system 1 includes a brake pedal 3 , a brake wheel cylinder 4 , an oil pump 5 , a brake booster 6 , an accumulator 7 , a charge valve 8 and a solenoid valve 9 .

The brake pedal 3 is an operation pedal that is operated by the driver of the forklift 2 by stepping on it.

The brake wheel cylinder 4 is a hydraulic brake device that applies braking force to the wheels 10 of the forklift 2 using hydraulic oil. The brake wheel cylinders 4 have, for example, brake discs or brake drums.

The oil pump 5 is rotationally driven by a pump motor 11 . The pump motor 11 is a drive source that drives the oil pump 5 to rotate. The oil pump 5 sucks up hydraulic oil stored in the oil tank 12 and supplies it to the brake booster 6 and the brake wheel cylinder 4 .

A suction filter 13 for preventing dust from entering the oil pump 5 is arranged in the oil tank 12 . The suction filter 13 is connected with the oil pump 5 via the hydraulic fluid flow path 14 . The hydraulic fluid flow path 14 is a flow path through which hydraulic fluid flows from the suction filter 13 to the oil pump 5 .

The brake booster 6 is connected to the brake pedal 3 and arranged between the oil pump 5 and the brake wheel cylinder 4 . The brake booster 6 is a booster that assists the driver's force to operate the brake pedal 3 .

The brake booster 6 is connected to the oil tank 12 via hydraulic oil passages 15 and 16 . The hydraulic oil passages 15 and 16 are passages through which the hydraulic oil flows from the brake booster 6 to the oil tank 12 . A cooler 17 that cools the hydraulic oil returning to the oil tank 12 is arranged in the hydraulic oil flow path 16 .

The accumulator 7 accumulates hydraulic oil discharged from the discharge port 5 a of the oil pump 5 . The accumulator 7 is filled with an accumulator gas such as nitrogen gas. Hydraulic oil from the oil pump 5 is sealed in the accumulator 7 by a valve and accumulated. When the valve is opened in this state, the hydraulic oil in the accumulator 7 is pushed out and released by the expansion force of the accumulated pressure gas.

A charge valve 8 is arranged between the oil pump 5 and the brake booster 6 and the accumulator 7 . The charge valve 8 switches between an oil passage in which the hydraulic oil from the oil pump 5 is supplied to the brake booster 6 and an oil passage in which the hydraulic oil from the oil pump 5 is supplied to the accumulator 7 according to the pressure of the accumulator 7. .

The charge valve 8 is connected to the discharge port 5 a of the oil pump 5 via the hydraulic fluid flow path 18 . The hydraulic fluid flow path 18 is a flow path through which hydraulic fluid flows from the oil pump 5 to the charge valve 8 .

Also, the charge valve 8 is connected to the brake booster 6 via a hydraulic fluid flow path 19 . The hydraulic fluid flow path 19 is a flow path through which hydraulic fluid flows from the charge valve 8 to the brake booster 6 .

Also, the charge valve 8 is connected to the accumulator 7 via a hydraulic fluid flow path 20 . The hydraulic fluid flow path 20 is a flow path through which hydraulic fluid flows from the charge valve 8 to the accumulator 7 .

The charge valve 8 switches between an oil passage that communicates the hydraulic oil passage 18 with the hydraulic oil passage 19 and an oil passage that connects the hydraulic oil passage 18 with the hydraulic oil passages 19 and 20 .

Specifically, until the pressure of the accumulator 7 reaches a set pressure, the charge valve 8 communicates the hydraulic fluid passage 18 with the hydraulic fluid passages 19 and 20, thereby supplying the hydraulic fluid from the oil pump 5. The accumulator 7 is supplied preferentially. When the pressure of the accumulator 7 reaches the set pressure, the charge valve 8 connects the hydraulic fluid flow path 18 and the hydraulic fluid flow path 19 and blocks the hydraulic fluid flow path 18 and the hydraulic fluid flow path 20. Hydraulic oil from the oil pump 5 is supplied to the brake booster 6. The set pressure of the charge valve 8 can be manually adjusted.

A solenoid valve 9 is arranged between the brake booster 6 and accumulator 7 and the brake wheel cylinder 4 . The solenoid valve 9 is an electromagnetic proportional switching valve that switches the hydraulic fluid flow between the brake booster 6 and accumulator 7 and the brake wheel cylinder 4 .

The solenoid valve 9 is connected to the brake booster 6 via a hydraulic fluid flow path 21 . The hydraulic fluid flow path 21 is a first hydraulic fluid flow path through which hydraulic fluid flows bidirectionally between the brake booster 6 and the solenoid valve 9 .

Also, the solenoid valve 9 is connected to the accumulator 7 via a hydraulic fluid flow path 22 . The hydraulic fluid flow path 22 is a second hydraulic fluid flow path through which hydraulic fluid flows from the accumulator 7 to the solenoid valve 9 . The hydraulic fluid flow path 22 is a flow path through which hydraulic fluid that does not pass through the brake booster 6 flows toward the solenoid valve 9 .

Also, the solenoid valve 9 is connected to the brake wheel cylinder 4 via a hydraulic fluid flow path 23 . The hydraulic fluid flow path 23 is a third hydraulic fluid flow path through which hydraulic fluid flows bidirectionally between the solenoid valve 9 and the brake wheel cylinder 4 .

The solenoid valve 9, as shown in FIG. , a second open position 9b that connects the hydraulic fluid flow path 22 and the hydraulic fluid flow path 23 and blocks the hydraulic fluid flow path 21 and the hydraulic fluid flow path 23, and a first open position 9a and a second open position 9b , and has a closed position 9c that blocks the hydraulic fluid flow paths 21, 22 and 23 from each other.

The solenoid valve 9 is provided with a solenoid operation portion 24 to which an electric signal is input. When the solenoid valve 9 is at the first open position 9a, the opening of the solenoid valve 9 is constant. When the solenoid valve 9 is in the second open position 9b, the opening degree of the solenoid valve 9 changes according to the value of the electrical signal (for example, current value) input to the solenoid operation section 24. FIG. Specifically, the greater the value of the electric signal input to the solenoid operation portion 24, the greater the degree of opening of the solenoid valve 9 becomes.

In a normal state in which no electric signal is supplied to the solenoid operating portion 24, the solenoid valve 9 is at the first open position 9a (illustrated) by the spring 25. As shown in FIG. When the solenoid operation portion 24 is energized by supplying an electric signal to the solenoid operation portion 24, the solenoid valve 9 is switched from the first open position 9a to the second open position 9b.

1 and 2, the brake system 1 includes an automatic operation switch 30, a pressure sensor 31, a potentiometer 32, an alarm 33, a brake controller 34, a pressure sensor 35, and a pump controller. 36.

The automatic operation switch 30 is an instruction operation unit for the driver to instruct automatic operation of the forklift 2 . When the automatic operation switch 30 is OFF, the operation mode of the forklift 2 is the manual operation mode. The manual operation mode is a mode in which the forklift 2 is manually operated by the driver. When the automatic operation switch 30 is ON, the operation mode of the forklift 2 is the automatic operation mode. The automatic operation mode is a mode in which the automatic operation controller 37 controls the forklift 2 to automatically travel.

When automatic operation of the forklift 2 is instructed by turning on the automatic operation switch 30, the automatic operation controller 37 automatically drives the forklift 2 based on the detection values of various sensors. 38. The drive unit 38 has a travel motor that rotates the wheels 10 of the forklift 2 and a steering motor that steers the wheels 10 .

A pressure sensor 31 is connected to the hydraulic fluid flow path 23 . The pressure sensor 31 constitutes a brake pressure detection section that detects the pressure of hydraulic fluid supplied to the brake wheel cylinder 4 as brake pressure.

The potentiometer 32 detects the depression amount (operation amount) of the brake pedal 3 . The potentiometer 32 constitutes a detection section that detects whether or not the brake pedal 3 has been operated during automatic operation of the forklift 2 .

The alarm device 33 sounds or displays an alarm to the driver when it is detected that the brake pedal 3 has been operated during automatic operation of the forklift 2 .

The brake controller 34 is composed of a CPU, a RAM, a ROM, an input/output interface, and the like. The brake controller 34 has a braking control section 41 and an automatic operation stop control section 42 .

The braking control unit 41 controls the solenoid valve 9 when braking the forklift 2 during automatic operation of the forklift 2 . The braking control unit 41 switches the position of the solenoid valve 9 from the first open position 9a to the second open position 9b when the forklift 2 is braked during automatic operation of the forklift 2. The solenoid operation part 24 of the solenoid valve 9 is controlled so that the oil pressure is adjusted to the set pressure.

FIG. 3 is a flow chart showing the procedure of the braking control process executed by the braking control section 41. As shown in FIG. This process is executed when the automatic operation switch 30 is turned on. Note that the solenoid valve 9 is at the first open position 9a before this process is executed.

In FIG. 3, the braking control unit 41 first acquires a control command signal from the automatic driving controller 37 (step S101). Then, the braking control unit 41 determines whether it is time to start braking the forklift 2 based on the control command signal from the automatic operation controller 37 (step S102). When the braking control unit 41 determines that it is not the time to start braking the forklift 2, the above step S101 is executed again.

When the brake control unit 41 determines that it is time to start braking the forklift 2, the brake control unit 41 outputs a control signal for switching the position of the solenoid valve 9 from the first open position 9a to the second open position 9b. Output to the unit 24 (step S103). As a result, the hydraulic oil flow path 22 and the hydraulic oil flow path 23 are communicated with each other, so that the hydraulic oil is supplied from the accumulator 7 to the brake wheel cylinder 4 and braking force is applied to the wheels 10 .

Subsequently, the braking control unit 41 acquires the detection value of the pressure sensor 31 (step S104). Based on the detection value of the pressure sensor 31, the braking control unit 41 sends a control signal to the solenoid operation unit 24 for adjusting the pressure of the hydraulic oil (brake pressure) supplied to the brake wheel cylinder 4 to the set pressure. Output (step S105). Information on the set pressure is included in the control command signal of the automatic operation controller 37 . As a result, the solenoid valve 9 is adjusted to open at the second open position 9b at an opening degree corresponding to the set pressure.

Subsequently, the braking control unit 41 acquires a control command signal for the automatic driving controller 37 (step S106). Then, the braking control unit 41 determines whether it is time to end the braking of the forklift 2 based on the control command signal from the automatic operation controller 37 (step S107). When the braking control unit 41 determines that the braking end timing of the forklift 2 is not reached, the above step S106 is executed again.

When the braking control unit 41 determines that it is time to end the braking of the forklift 2, the control signal for switching the position of the solenoid valve 9 from the second open position 9b to the first open position 9a is applied to the solenoid valve 9. The data is output to the unit 24 (step S108), and the above step S101 is executed again. As a result, the hydraulic oil flow path 22 and the hydraulic oil flow path 23 are blocked, so that the supply of hydraulic oil from the accumulator 7 to the brake wheel cylinder 4 is stopped, and the application of the braking force to the wheels 10 is released. .

Returning to FIG. 2, when the potentiometer 32 detects that the brake pedal 3 has been operated during automatic operation of the forklift, the automatic operation stop control unit 42 detects that the solenoid valve 9 is in the second open position 9b. The solenoid operation part 24 of the solenoid valve 9 is controlled so that the position of the solenoid valve 9 is switched from the second open position 9b to the first open position 9a.

FIG. 4 is a flow chart showing the procedure of the automatic operation stop control process executed by the automatic operation stop control unit 42. As shown in FIG. This process is also executed when the automatic operation switch 30 is turned on.

In FIG. 4, the automatic operation stop control unit 42 determines whether the current position of the solenoid valve 9 is the second open position 9b (step S111). A determination as to whether the current position of the solenoid valve 9 is the second open position 9b is made based on a control signal output from the braking control section 41 to the solenoid operation section 24 of the solenoid valve 9, for example.

When the automatic operation stop control unit 42 determines that the current position of the solenoid valve 9 is the second open position 9b, it acquires the detection value of the potentiometer 32 (step S112). Then, the automatic operation stop control unit 42 determines whether or not the brake pedal 3 is operated based on the detection value of the potentiometer 32 (step S113). When the automatic operation stop control unit 42 determines that the brake pedal 3 is not operated, the above step S111 is executed again.

When the automatic operation stop control unit 42 determines that the brake pedal 3 has been operated, it outputs a control signal for switching the position of the solenoid valve 9 from the second open position 9b to the first open position 9a. Output to the unit 24 (step S114). As a result, the hydraulic oil flow path 22 and the hydraulic oil flow path 23 are blocked, so that the brake control by the automatic operation of the forklift 2 is forcibly stopped.

Then, the automatic operation stop control unit 42 outputs an alarm signal to the alarm device 33 (step S115), and executes the above step S111 again. As a result, the alarm device 33 warns the driver that the brake control by the automatic operation of the forklift 2 has been forcibly stopped.

Returning to FIG. 2 , the pressure sensor 35 is connected to the hydraulic fluid flow path 20 . The pressure sensor 35 constitutes an accumulator pressure detection section that detects the pressure of the accumulator 7 .

The pump controller 36 includes a CPU, RAM, ROM, input/output interface, and the like. The pump controller 36 constitutes a pump control section that controls the pump motor 11 based on the pressure of the accumulator 7 during automatic operation of the forklift 2 . The pump controller 36 controls the pump motor 11 to stop the rotation of the oil pump 5 when the pressure of the accumulator 7 is equal to or higher than the specified pressure.

FIG. 5 is a flow chart showing the procedure of the oil pump control process executed by the pump controller 36. As shown in FIG. This process is executed when an ignition switch (not shown) of the forklift 2 is turned on.

In FIG. 5, the pump controller 36 first acquires an operation signal of the automatic operation switch 30 (step S121). Then, the pump controller 36 determines whether the operation signal of the automatic operation switch 30 is an ON signal (step S122).

When the pump controller 36 determines that the operation signal of the automatic operation switch 30 is not the ON signal, it determines that the operation mode of the forklift 2 is the manual operation mode, and performs control to rotate the pump motor 11 at a specified rotation speed. A signal is output to the pump motor 11 (step S123), and the above step S121 is executed again. As a result, the oil pump 5 rotates at the specified number of revolutions.

When the pump controller 36 determines that the operation signal of the automatic operation switch 30 is the ON signal, it determines that the operation mode of the forklift 2 is the automatic operation mode, and acquires the detection value of the pressure sensor 35 (step S124). ). Then, the pump controller 36 determines whether the pressure of the accumulator 7 is equal to or higher than the specified pressure based on the detection value of the pressure sensor 35 (step S125). The prescribed pressure is the pressure at which the accumulator 7 is maintained in a pressure-accumulated state.

When the pump controller 36 determines that the pressure of the accumulator 7 is lower than the specified pressure, it outputs a control signal to the pump motor 11 to rotate the pump motor 11 at the specified number of revolutions (step S123), and performs the above steps. S121 is executed again. As a result, the oil pump 5 rotates at the specified number of revolutions.

When the pump controller 36 determines that the pressure of the accumulator 7 is equal to or higher than the specified pressure, the pump controller 36 outputs a control signal to the pump motor 11 to stop the rotation of the pump motor 11 (step S126), and the above step S121 is performed. Try again. As a result, the rotation of the oil pump 5 is stopped.

In the brake system 1 as described above, the solenoid valve 9 is at the first open position 9a in the manual operation mode in which the automatic operation switch 30 is not turned on. In this case, when the brake pedal 3 is operated by the driver, the hydraulic fluid in the brake booster 6 flows through the hydraulic fluid channel 21 , the solenoid valve 9 and the hydraulic fluid channel 23 and is supplied to the brake wheel cylinder 4 . As a result, the brake wheel cylinder 4 operates to apply a braking force to the wheels 10 .

When the driver turns on the automatic operation switch 30, the operation mode of the forklift 2 is switched from the manual operation mode to the automatic operation mode, and the automatic operation controller 37 controls the drive unit 38 so that the forklift 2 automatically travels. .

When the forklift 2 stops or decelerates during automatic travel of the forklift 2, the position of the solenoid valve 9 is switched from the first open position 9a to the second open position 9b by a control signal from the brake controller 34, and the hydraulic oil flow path 22 is opened. and the hydraulic oil flow path 23 are communicated with each other. However, since the position of the solenoid valve 9 is temporarily changed to the closed position 9c while the position of the solenoid valve 9 is being switched, backflow of hydraulic oil from the brake wheel cylinder 4 to the accumulator 7 is prevented.

The hydraulic fluid accumulated in the accumulator 7 flows through the hydraulic fluid channel 22 , the solenoid valve 9 and the hydraulic fluid channel 23 and is supplied to the brake wheel cylinder 4 . As a result, the brake wheel cylinder 4 operates to apply a braking force to the wheels 10 .

When the pressure of the accumulator 7 becomes low and the pressure accumulation state of the accumulator 7 is no longer maintained, the charge valve 8 supplies the hydraulic oil from the oil pump 5 to the accumulator 7, whereby the accumulator 7 enters the pressure accumulation state.

As described above, in this embodiment, the solenoid valve 9 is normally in the first open position 9a, and the forklift 2 is manually operated. When the brake pedal 3 is operated by the driver during manual operation of the forklift 2, hydraulic fluid from the brake booster 6 flows through the hydraulic fluid flow path 21, the solenoid valve 9, and the hydraulic fluid flow path 23 to the brake wheel cylinder 4. A braking force is applied to the wheels 10 by the brake wheel cylinders 4 . On the other hand, when braking the forklift 2 during automatic operation of the forklift 2, the solenoid operation portion 24 of the solenoid valve 9 is controlled so that the solenoid valve 9 is switched from the first open position 9a to the second open position 9b. Therefore, the hydraulic fluid that does not pass through the brake booster 6 flows through the hydraulic fluid flow path 22, the solenoid valve 9 and the hydraulic fluid flow path 23 and is supplied to the brake wheel cylinder 4, so that the wheel 10 is controlled by the brake wheel cylinder 4. Power is given. Here, as the solenoid valve 9, an existing electromagnetic proportional switching valve can be used. Therefore, it is not necessary to newly design and manufacture a device for automatically braking the forklift 2 . As a result, it is possible to achieve both brake operation during manual operation and brake control during automatic operation at low cost.

Further, during automatic operation of the forklift 2, hydraulic oil is supplied to the brake wheel cylinder 4 without automatically operating the brake pedal 3. Therefore, variations in the braking force applied to the wheels 10 are suppressed. The time lag that occurs when the braking force is applied to the wheels 10 is reduced.

Further, in this embodiment, when braking the forklift 2 during automatic operation of the forklift 2, the solenoid operating portion of the solenoid valve 9 is adjusted so that the pressure of the hydraulic oil supplied to the brake wheel cylinder 4 is adjusted to the set pressure. 24 is controlled. Therefore, the braking force applied to the wheels 10 of the forklift 2 can be easily adjusted.

Further, in this embodiment, when the forklift 2 is braked during automatic operation of the forklift 2, the hydraulic oil accumulated in the accumulator 7 flows through the hydraulic oil flow path 22, the solenoid valve 9, and the hydraulic oil flow path 23 to brake. By being supplied to the wheel cylinder 4 , braking force is applied to the wheel 10 by the brake wheel cylinder 4 . Therefore, during automatic operation of the forklift 2, the forklift 2 can be effectively braked with a simple configuration. Existing products can also be used as the accumulator 7 and the charge valve 8 .

Further, in this embodiment, when the pressure of the accumulator 7 is equal to or higher than the specified pressure, the rotation of the oil pump 5 is stopped. When the forklift 2 is braked during the automatic operation of the forklift 2, the hydraulic oil is supplied from the accumulator 7 to the brake wheel cylinder 4, so the oil pump 5 does not need to be operated all the time. Therefore, by stopping the rotation of the oil pump 5, the energy consumption of the oil pump 5 is reduced. Therefore, the fuel efficiency of the forklift 2 is improved, and the operating time of the forklift 2 can be extended.

Further, in the present embodiment, when the driver operates the brake pedal 3 in a state where the solenoid valve 9 is in the second open position 9b by braking the forklift 2 during automatic operation of the forklift 2, the solenoid valve The position of 9 is switched from the second open position 9b to the first open position 9a, and braking of the forklift 2 by automatic operation is forcibly stopped. Therefore, braking force is applied to the wheels 10 by supplying hydraulic oil from the brake booster 6 to the brake wheel cylinders 4 . Thus, when the brake pedal 3 is operated during automatic operation of the forklift 2, automatic operation is switched to manual operation. Therefore, it is possible to prevent the brake control from being performed against the intention of the driver.

FIG. 6 is a flowchart showing a modification of the procedure of the oil pump control process executed by the pump controller 36, and corresponds to FIG.

In FIG. 6, the pump controller 36 executes the above procedures S121, S122, S124 and S125. When the pump controller 36 determines in step S125 that the pressure of the accumulator 7 is equal to or higher than the specified pressure, it outputs a control signal to the pump motor 11 to reduce the rotation speed of the pump motor 11 below the specified rotation speed. (step S126A). As a result, the rotational speed of the oil pump 5 is reduced below the prescribed rotational speed.

In this modification, the energy consumption of the oil pump 5 is reduced by reducing the number of revolutions of the oil pump 5 . Therefore, as in the above embodiment, the fuel efficiency of the forklift 2 can be improved, and the operation time of the forklift 2 can be extended.

In addition, this invention is not limited to the said embodiment. For example, in the above-described embodiment, the solenoid valve 9 is an electromagnetic proportional switching valve whose opening degree is variable at the second open position 9b. An electromagnetic switching valve or the like having a constant degree of opening at the position 9b may be used.

Further, in the above embodiment, the brake controller 34 and the pump controller 36 are provided, but the configuration is not particularly limited, and the brake controller 34 and the pump controller 36 may be composed of one controller. In this case, one controller has the braking control section 41, the automatic operation stop control section 42, and a pump control section that functions as the pump controller .

Further, in the above embodiment, the oil pump 5 is driven by the pump motor 11, but the drive source for driving the oil pump 5 is not particularly limited to the pump motor 11, and an engine 50 as shown in FIG. may be

When the drive source is the engine 50, the control of the rotational speed of the oil pump 5 is unnecessary, so the pressure sensor 35 and the pump controller 36 may be omitted. Moreover, when the drive source is the engine 50, the forklift 2 may be provided with an inching pedal. In this case, even when the inching pedal is operated by the driver, hydraulic fluid is supplied from the brake booster 6 to the brake wheel cylinder 4 , so braking force is applied to the wheels 10 .

Further, in the above embodiment, the brake booster 6 is arranged between the oil pump 5 and the brake wheel cylinder 4. However, as a booster for assisting the driver's force to operate the brake pedal 3, a brake It is not limited to the booster 6, and may be, for example, a brake valve, a master cylinder, or the like.

Further, in the above embodiment, by detecting the amount of operation of the brake pedal 3 by the potentiometer 32, it is detected whether or not the brake pedal 3 is operated during automatic operation of the forklift 2. is not limited. For example, it may be detected whether or not the brake pedal 3 is operated during automatic operation of the forklift 2 using a contact switch or the like that detects whether or not the brake pedal 3 is in contact.

Furthermore, although the brake system 1 of the above embodiment is mounted on the forklift 2, the present invention can also be applied to industrial vehicles other than forklifts (for example, towing tractors, etc.) as long as they are provided with brake pedals. .

DESCRIPTION OF SYMBOLS 1... Brake system, 2... Forklift (industrial vehicle), 3... Brake pedal, 4... Brake wheel cylinder (hydraulic brake device), 5... Oil pump, 6... Brake booster (booster), 7... Accumulator, 8... Charge valve 9 Solenoid valve 9a First open position 9b Second open position 10 Wheel 21 Hydraulic oil passage (first hydraulic oil passage) 22 Hydraulic oil passage (second Hydraulic oil passage), 23 Hydraulic oil passage (third hydraulic oil passage), 31 Pressure sensor (brake pressure detector), 32 Potentiometer (detector), 35 Pressure sensor (accumulator pressure detector) , 36... pump controller (pump control section), 41... braking control section, 42... automatic operation stop control section.

Claims (5)

In the brake system that brakes industrial vehicles that can operate automatically,
a brake pedal operated by a driver of the industrial vehicle;
a hydraulic brake device that applies a braking force to the wheels of the industrial vehicle;
an oil pump that supplies hydraulic oil to the hydraulic brake device;
a booster disposed between the oil pump and the hydraulic brake device for assisting the driver's force to operate the brake pedal;
a solenoid valve disposed between the booster and the hydraulic brake device;
a first hydraulic fluid flow path through which hydraulic fluid flows between the booster and the solenoid valve;
a second hydraulic fluid flow path through which hydraulic fluid that does not pass through the booster flows toward the solenoid valve;
a third hydraulic fluid flow path through which hydraulic fluid flows between the solenoid valve and the hydraulic brake device;
a braking control unit that controls the solenoid valve when braking the industrial vehicle during automatic operation of the industrial vehicle;
a first open position in which the solenoid valve communicates the first hydraulic fluid flowpath and the third hydraulic fluid flowpath and blocks communication between the second hydraulic fluid flowpath and the third hydraulic fluid flowpath; a second open position that communicates the second hydraulic fluid flow path and the third hydraulic fluid path and blocks the first hydraulic fluid path and the third hydraulic fluid path;
The brake control unit operates a solenoid of the solenoid valve so that the position of the solenoid valve is switched from the first open position to the second open position when the industrial vehicle is braked during automatic operation of the industrial vehicle. Brake system that controls the parts. further comprising a brake pressure detection unit that detects the pressure of hydraulic oil supplied to the hydraulic brake device;
The braking control unit switches the position of the solenoid valve from the first open position to the second open position when braking the industrial vehicle during automatic operation of the industrial vehicle, and the brake control unit switches the position of the solenoid valve from the first open position to the second open position. 2. The brake system according to claim 1, wherein the solenoid operation part is controlled so that the pressure of the hydraulic oil applied to the brake is adjusted to the set pressure. an accumulator for accumulating hydraulic oil discharged from the oil pump;
An oil passage disposed between the oil pump, the booster, and the accumulator, through which hydraulic oil from the oil pump is supplied to the accumulator in accordance with the pressure of the accumulator, and hydraulic oil from the oil pump is further provided with a charge valve that switches the oil path supplied to the booster,
3. The brake system according to claim 1, wherein said second hydraulic fluid flow path is a flow path through which hydraulic fluid flows from said accumulator to said solenoid valve. an accumulator pressure detection unit that detects the pressure of the accumulator;
a pump control unit that controls a drive source that rotationally drives the oil pump based on the pressure of the accumulator during automatic operation of the industrial vehicle;
4. The pump control unit according to claim 3, wherein when the pressure of the accumulator is equal to or higher than a specified pressure, the pump control unit controls the driving source so as to stop the rotation of the oil pump or decrease the rotation speed of the oil pump. brake system. a detection unit that detects whether the brake pedal has been operated during automatic operation of the industrial vehicle;
When the detection unit detects that the brake pedal is operated during automatic operation of the industrial vehicle while the solenoid valve is in the second open position, the solenoid valve is positioned in the second open position. 5. The brake system according to any one of claims 1 to 4, further comprising an automatic shutdown control section that controls the solenoid operation section to switch from the position to the first open position.

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