JP2020128125A - Brake system of industrial vehicle - Google Patents

Abstract

To provide a brake system of an industrial vehicle that can stop the industrial vehicle in more slowly at emergency stop time than at normal stop time.SOLUTION: A braking system 15 comprises: a first electromagnetic switch valve 27 arranged between an accumulator 26 and a hydraulic pressure cylinder 24; a first flow-rate control valve 28 and a second flow-rate valve 29, arranged in parallel between the first electromagnetic switch valve 27 and the hydraulic pressure cylinder 24, which control a flow rate of hydraulic oil to be supplied from the accumulator 26 to the hydraulic pressure cylinder 24; and a second electromagnetic switch valve 30, arranged among the first electromagnetic switch valve 27, the first flow-rate control valve 28 and the second flow-rate control valve 29, which is switched to either of a first permission position 30a at which flow of the hydraulic oil between the first electromagnetic switch valve 27 and the first flow-rate control valve 28 is permitted and a second permission position 30b at which flow of the hydraulic oil between the first electromagnetic switch valve 27 and the second flow-rate control valve 29 is permitted. An aperture of the second flow-rate control valve 29 is smaller than an aperture of the first flow-rate control valve 28.SELECTED DRAWING: Figure 2

Description

The present invention relates to a braking system for industrial vehicles.

As a brake system used for an industrial vehicle or the like, for example, the technique described in Patent Document 1 is known. The brake system described in Patent Document 1 is arranged between a brake pedal, a vacuum booster and a master cylinder connected to the brake pedal via a rod, a brake pedal and a vacuum booster, and a rod. A first hydraulic cylinder having a connected piston, a second hydraulic cylinder connected to the first hydraulic cylinder via a hydraulic pipe, a movable member that pushes the piston of the second hydraulic cylinder, and a movable member that is driven. It is equipped with a motor. When the motor is rotationally driven 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 moves forward and pushes the rod, the vacuum booster is operated and brake hydraulic pressure is generated in the master cylinder.

Further, in Patent Document 2, when a normal brake pedal is used during normal braking, the vehicle is mainly decelerated by an electric brake, the vehicle is stopped immediately before the stop by cooperation of an electric brake and a mechanical brake, and during emergency braking. It is described that when the emergency brake pedal is used, the mechanical brake and the electric brake are simultaneously activated to decelerate and stop the vehicle.

JP, 10-152028, A JP, 2016-22804, A

By the way, in an industrial vehicle such as a forklift truck, there is a case where it is desired to change the degree of braking depending on the traveling situation. For example, when an abnormality or the like occurs while the industrial vehicle is running, the power source is cut off and the industrial vehicle is brought to an emergency stop. However, industrial vehicles often carry luggage, and luggage is loaded in front of the vehicles. Therefore, at the time of emergency stop, it is necessary to stop the industrial vehicle more slowly than at the time of normal stop in consideration of luggage. In the technique described in Patent Document 2, the vehicle is stopped faster during emergency stop (during emergency braking) than during normal stop (during normal braking).

An object of the present invention is to provide a brake system for an industrial vehicle that can stop the industrial vehicle more slowly during an emergency stop than during a normal stop.

One aspect of the present invention is a brake system of an industrial vehicle that operates a brake unit by pressing a brake pedal provided in the industrial vehicle to brake the industrial vehicle. Of the hydraulic cylinder that is driven by the hydraulic oil and presses the brake pedal, the hydraulic pressure source and the supply position that supplies the hydraulic oil from the hydraulic source to the hydraulic cylinder, and the hydraulic cylinder and the tank. A first electromagnetic switching valve that is switched to either a return position that returns the hydraulic oil to the tank, and a hydraulic oil that is arranged in parallel between the first electromagnetic switching valve and the hydraulic cylinder and that is supplied from the hydraulic source to the hydraulic cylinder. A first flow rate control valve and a second flow rate control valve that respectively control the flow rates of the first and second flow rate control valves, and a first electromagnetic changeover valve and a second flow rate control valve. A first permissible position for allowing the flow of hydraulic oil between the first flow control valve and the first electromagnetic switching valve while allowing the flow of hydraulic oil between the first electromagnetic switching valve and the second flow control valve; A second electromagnetic switching valve that is switched to any of a second allowable position that blocks the flow of hydraulic oil between the first electromagnetic switching valve and the first flow control valve; It has a solenoid operating part, and when the first solenoid operating part is energized, the position of the first electromagnetic switching valve is the return position, and when the first solenoid operating part is de-energized, the position of the first electromagnetic switching valve is Is the supply position, the first switch section is connected between the first solenoid operating section and the power source, and the second electromagnetic switching valve has the second solenoid operating section connected to the power source. When the 2-solenoid operating portion is energized, the position of the second electromagnetic switching valve becomes the first allowable position, and when the second solenoid operating portion is de-energized, the position of the second electromagnetic switching valve becomes the second allowable position. The opening degree of the second flow rate control valve is smaller than the opening degree of the first flow rate control valve.

In such a braking system, when the first switch section is opened during normal stop of the industrial vehicle, the energization of the first solenoid operating section of the first electromagnetic switching valve is released, so that the position of the first electromagnetic switching valve is changed. Becomes the supply position and the second solenoid operating portion of the second electromagnetic switching valve is energized, so that the position of the second electromagnetic switching valve becomes the first allowable position. Therefore, the hydraulic oil from the hydraulic source is supplied to the hydraulic cylinder through the first flow control valve, and the brake pedal is pressed by the hydraulic cylinder, so that the industrial vehicle is braked. On the other hand, at the time of the emergency stop of the industrial vehicle, the power is cut off, so that the first solenoid switching valve is de-energized, so that the position of the first solenoid switching valve becomes the supply position, and Since the power is cut off, the second solenoid switching valve is de-energized so that the position of the second solenoid switching valve becomes the second allowable position. Therefore, hydraulic oil from the hydraulic source is supplied to the hydraulic cylinder through the second flow control valve, and the brake pedal is pressed by the hydraulic cylinder, so that the industrial vehicle is braked.

Here, by setting the opening of the second flow control valve to be smaller than the opening of the first flow control valve, the flow rate of the hydraulic oil flowing through the second flow control valve is the flow rate of the hydraulic oil flowing through the first flow control valve. Less than. Therefore, during an emergency stop in which hydraulic oil flows through the second flow control valve, the operating speed of the hydraulic cylinder becomes lower than during normal stop in which hydraulic oil flows through the first flow control valve, so the deceleration of the industrial vehicle becomes low. .. As a result, the industrial vehicle can be stopped more slowly during the emergency stop than during the normal stop. As a result, it is possible to stably stop the industrial vehicle loaded with the luggage at the time of emergency stop.

The first allowable position allows the flow of hydraulic oil between the first electromagnetic switching valve and the first flow rate control valve, and blocks the flow of hydraulic oil between the first electromagnetic switching valve and the second flow rate control valve. It may be at the position. With such a configuration, during normal stop, the hydraulic oil from the hydraulic source is supplied to the hydraulic cylinder through the first flow control valve without passing through the second flow control valve, and during emergency stop, the hydraulic oil from the hydraulic source is supplied. Is supplied to the hydraulic cylinder through the second flow rate control valve without passing through the first flow rate control valve. Therefore, it becomes easy to adjust the degree of brake application during normal stop and emergency stop.

A second switch unit may be connected between the second solenoid operating unit and the power supply. In such a configuration, by controlling the second switch unit so that the second solenoid operating unit of the second electromagnetic switching valve is de-energized, the second electromagnetic switching valve moves from the first allowable position to the second allowable position. Switch to. Therefore, the hydraulic oil from the hydraulic power source is supplied to the hydraulic cylinder through the second flow rate control valve even during the normal stop, so that it is possible to apply the same brake to the industrial vehicle as during the emergency stop.

The brake system further includes a load detection unit that detects a load load of the industrial vehicle, and a control unit that controls to open the second switch unit when the load load detected by the load detection unit is equal to or more than a threshold value. Good. With such a configuration, when the load of the industrial vehicle is greater than or equal to the threshold value, the second switch section is open. Therefore, since the second solenoid operating portion of the second electromagnetic switching valve is de-energized, the second electromagnetic switching valve switches from the first allowable position to the second allowable position. As a result, even when the vehicle is normally stopped, it is possible to stably stop the industrial vehicle on which the luggage is loaded.

According to the present invention, an industrial vehicle can be stopped more slowly during an emergency stop than during a normal stop.

It is a side view which shows a forklift as an industrial vehicle provided with the brake system which concerns on embodiment of this invention. It is a schematic block diagram which shows the brake system of the industrial vehicle which concerns on 1st Embodiment of this invention. It is a schematic block diagram which shows the modification of the brake system shown by FIG. It is a schematic block diagram which shows the brake system of the industrial vehicle which concerns on 2nd Embodiment of this invention. 5 is a flowchart showing a procedure of a valve relay control process executed by the automatic operation controller shown in FIG. 4. It is a schematic block diagram which shows the modification of the brake system shown by FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a side view showing a forklift as an industrial vehicle including a brake system according to an embodiment of the present invention. In FIG. 1, a forklift 1 that is an industrial vehicle according to the present embodiment is a counter-type electric forklift. The forklift 1 includes a traveling device 2 and a cargo handling device 3 that is disposed on the front side of the traveling device 2 and that lifts and lowers the cargo W.

The traveling device 2 includes a vehicle body 4, a front wheel 5 that is two left and right driving wheels arranged at a front portion of the vehicle body 4, and a rear wheel 6 that is two left and right steered wheels arranged at a rear portion of the vehicle body 4. It has a traveling motor 7 for rotating the front wheels 5, a cargo handling motor 8 for rotationally driving a cargo handling hydraulic pump (not shown), and a battery 9 for supplying electric power to the travel motor 7 and the cargo handling motor 8.

The cargo handling device 3 is provided with a mast 10 standing upright on the front end of the vehicle body 4, a pair of forks 12 mounted on the mast 10 via a lift bracket 11, and carrying a load W, and lifting and lowering the fork 12. It has a lift cylinder 13 that causes the mast 10 to tilt and a tilt cylinder 14 that tilts the mast 10.

FIG. 2 is a schematic configuration diagram showing a brake system for an industrial vehicle according to the first embodiment of the present invention. In FIG. 2, the brake system 15 of the present embodiment is mounted on the forklift 1 for automatically operating the forklift 1. The forklift 1 is equipped with a steering system, a drive system, and the like in addition to the brake system 15 as a system related to automatic driving.

The brake system 15 performs the same operation as the work of stopping the forklift 1 by depressing a brake pedal 16 (described later) by an operator. The forklift 1 has a regenerative brake that is performed by the traveling motor 7 during deceleration. In automatic operation of the forklift 1, two brakes, a regenerative brake and a mechanical brake, are used together. While the forklift 1 is traveling, deceleration control is mainly performed by the regenerative brake. When the brake pedal 16 is depressed, the braking force of the regenerative brake is first increased to reduce the speed, and the mechanical brake is activated midway. In the present embodiment, detailed description of the control of the regenerative brake will be omitted, and a description will be given focusing on the case where the mechanical brake that operates from the middle is acted by pressing the brake pedal 16.

The forklift 1 includes a brake pedal 16 and a brake unit 17. The brake pedal 16 has a stepping portion 16a that is operated by the operator when the operator drives the vehicle (during manual operation). When the operator depresses the depression portion 16a, the brake pedal 16 is pushed.

The brake unit 17 operates when the brake pedal 16 is pressed. The brake unit 17 has a brake device 18 that brakes the front wheels 5 of the forklift 1, and a master cylinder 19 that operates the brake device 18.

The master cylinder 19 includes a cylinder tube 20, a piston 21 arranged in the cylinder tube 20, a piston rod 22 fixed to the piston 21, and an opposite side (base end side) of the piston rod 22 in the cylinder tube 20. ) And a spring 23 disposed in The tip of the piston rod 22 engages with the back surface of the brake pedal 16. When the brake pedal 16 is pushed, the piston rod 22 is pushed against the biasing force of the spring 23, and the hydraulic oil flows out from the master cylinder 19. The hydraulic oil discharged from the master cylinder 19 is supplied to the brake device 18, and the brake device 18 operates. As a result, the front wheels 5 are braked.

The brake system 15 is a system that operates the brake unit 17 by pushing the brake pedal 16 to apply a brake to the forklift 1. The brake system 15 includes a hydraulic cylinder 24, a hydraulic pump 25 for braking, an accumulator 26, a first electromagnetic switching valve 27, a first flow control valve 28, a second flow control valve 29, and a second electromagnetic switching. And a valve 30.

The hydraulic cylinder 24 is fixed to the vehicle body 4 of the forklift 1. The hydraulic cylinder 24 is driven by hydraulic oil and presses the brake pedal 16. The hydraulic cylinder 24 includes a cylinder tube 31, a piston 32 arranged in the cylinder tube 31, a piston rod 33 fixed to the piston 32, and a piston rod 33 side (tip side) in the cylinder tube 31. And a spring 34 that has been opened. The tip of the piston rod 33 is in contact with the central portion of the surface of the brake pedal 16.

The hydraulic pump 25 is driven by a drive motor 35. The hydraulic pump 25 sucks and discharges the hydraulic oil stored in the tank 36. A relief valve 37 is arranged between the discharge port 25 a of the hydraulic pump 25 and the tank 36.

The accumulator 26 stores the hydraulic oil discharged from the hydraulic pump 25. The accumulator 26 constitutes a hydraulic pressure source that supplies hydraulic oil. A check valve 38 that allows only the flow of hydraulic oil from the hydraulic pump 25 side to the accumulator 26 side is arranged between the discharge port 25a of the hydraulic pump 25 and the accumulator 26.

The first electromagnetic switching valve 27 is arranged between the hydraulic cylinder 24 and the accumulator 26 and the tank 36. The first electromagnetic switching valve 27 is a non-leak type three-way valve in which hydraulic oil does not easily leak. The first electromagnetic switching valve 27 is switched between a supply position 27a for supplying the hydraulic oil from the accumulator 26 to the hydraulic cylinder 24 and a return position 27b for returning the hydraulic oil from the hydraulic cylinder 24 to the tank 36.

The supply position 27a is a position that allows the supply of the hydraulic oil from the accumulator 26 to the hydraulic cylinder 24 and blocks the return of the hydraulic oil from the hydraulic cylinder 24 to the tank 36. The return position 27b is a position where the hydraulic oil is allowed to return from the hydraulic cylinder 24 to the tank 36 and the supply of hydraulic oil from the accumulator 26 to the hydraulic cylinder 24 is shut off.

A spring 39 is provided on the supply position 27a side of the first electromagnetic switching valve 27. A solenoid operating unit 40 (first solenoid operating unit) is provided on the return position 27b side of the first electromagnetic switching valve 27. The solenoid operating unit 40 is connected to the main power supply 42 of the forklift 1 via a contactor 41. When the solenoid operating unit 40 is energized, the position of the first electromagnetic switching valve 27 becomes the return position 27b. When the solenoid operating unit 40 is de-energized, the spring 39 causes the position of the first electromagnetic switching valve 27 to become the supply position 27a.

The first flow control valve 28 and the second flow control valve 29 are arranged in parallel between the first electromagnetic switching valve 27 and the hydraulic cylinder 24. The first flow rate control valve 28 and the second flow rate control valve 29 control the flow rate of the hydraulic oil supplied from the accumulator 26 to the hydraulic cylinder 24. The first flow control valve 28 and the second flow control valve 29 are slow return check valves having the same structure.

The first flow control valve 28 is a flow control valve for normal stop. The normal stop is a stop of the forklift 1 according to the automatic operation control of the forklift 1. The second flow control valve 29 is a flow control valve for emergency stop. The emergency stop is an emergency stop of the forklift 1 due to the interruption of the power supply or the like. The normal stop and emergency stop will be described later in detail.

The first flow control valve 28 has a main flow passage 44 having a variable throttle valve 43, and a bypass flow passage 45 connected to the main flow passage 44 so as to bypass the variable throttle valve 43. The hydraulic fluid from the first electromagnetic switching valve 27 flows through the variable throttle valve 43 toward the hydraulic cylinder 24. A check valve 46 that allows only the flow of hydraulic oil from the hydraulic cylinder 24 side to the first electromagnetic switching valve 27 side is arranged in the bypass flow passage 45.

The second flow rate control valve 29 has a main flow passage 48 having a variable throttle valve 47, and a bypass flow passage 49 connected to the main flow passage 48 so as to bypass the variable throttle valve 47. The hydraulic fluid from the first electromagnetic switching valve 27 flows through the variable throttle valve 47 toward the hydraulic cylinder 24. A check valve 50 that allows only the flow of hydraulic oil from the hydraulic cylinder 24 side to the first electromagnetic switching valve 27 side is arranged in the bypass flow passage 49.

The throttle opening of the variable throttle valve 47 is smaller than the throttle opening of the variable throttle valve 43. Therefore, the opening degree of the second flow rate control valve 29 is smaller than the opening degree of the first flow rate control valve 28. The throttle openings of the variable throttle valves 43 and 47 can be adjusted by adjusting screws (not shown). The openings of the variable throttle valves 43 and 47 can be finely adjusted according to the characteristics of the road surface on which the forklift 1 travels and the characteristics (shape, weight, etc.) of the cargo to be handled. As a result, the deceleration of the forklift 1 can be finely adjusted.

The second electromagnetic switching valve 30 is arranged between the first electromagnetic switching valve 27 and the first flow rate control valve 28 and the second flow rate control valve 29. The second electromagnetic switching valve 30 is a non-leakage three-way valve like the first electromagnetic switching valve 27.

The second electromagnetic switching valve 30 allows the flow of the hydraulic oil between the first electromagnetic switching valve 27 and the first flow rate control valve 28, and between the first electromagnetic switching valve 27 and the second flow rate control valve 29. In the first permissible position 30a for shutting off the flow of hydraulic oil, and the flow of hydraulic oil between the first electromagnetic switching valve 27 and the second flow rate control valve 29, the first electromagnetic switching valve 27 and the first electromagnetic switching valve 27 are allowed. It is switched to any one of the second allowable position 30b that shuts off the flow of the hydraulic oil between the flow control valve 28 and the flow control valve 28.

A spring 51 is provided on the second allowable position 30b side of the second electromagnetic switching valve 30. A solenoid operating unit 52 (second solenoid operating unit) is provided on the first allowable position 30a side of the second electromagnetic switching valve 30. The solenoid operating unit 52 is connected to the main power source 42 via the contactor 41. When the solenoid operating portion 52 is energized, the position of the second electromagnetic switching valve 30 becomes the first allowable position 30a. When the solenoid operating unit 52 is de-energized, the spring 51 causes the second electromagnetic switching valve 30 to move to the second allowable position 30b.

A valve relay 53 is connected between the solenoid operating unit 40 of the first electromagnetic switching valve 27 and the contactor 41. The valve relay 53 is a first switch unit that switches the electric power output from the main power supply 42.

The valve relay 53 is controlled by an ON/OFF signal output from an automatic operation controller 54 that controls automatic operation of the forklift 1. The automatic driving controller 54 includes a CPU, a RAM, a ROM, an input/output interface, and the like. When the ON signal is output from the automatic operation controller 54, the valve relay 53 is turned on (closed), and the solenoid operating unit 40 is energized. When the OFF signal is output from the automatic operation controller 54, the valve relay 53 is turned off (opened), and the solenoid operating unit 40 is de-energized.

An emergency stop circuit 55 is connected to the contactor 41. When the emergency stop signal is input to the emergency stop circuit 55, the contactor 41 forcibly shuts off the power output from the main power supply 42. When the emergency stop button 56 provided on the forklift 1 or the operator's wireless mobile terminal is operated, an emergency stop command is input from the emergency stop button 56 to the emergency stop circuit 55. In addition, an emergency stop command may be input to the emergency stop circuit 55 from the automatic operation controller 54.

The drive motor 35 described above is connected to the main power supply 42 via a contactor 41. A pump relay 57 is connected between the drive motor 35 and the contactor 41. The pump relay 57 switches the electric power output from the main power supply 42.

The main power source 42 and the contactor 41 are related to the electric power of the entire forklift 1. Electric power from the main power source 42 is supplied to the traveling motor 7 and the cargo handling motor 8 (see FIG. 1) via the contactor 41, a controller of the forklift 1 (not shown), a sensor for automatic operation, and a braking system such as a system for steering. It is also supplied to systems other than 15.

The brake system 15 also includes a pressure sensor 58 and a relay controller 59. The pressure sensor 58 detects the pressure of the accumulator 26. The pressure sensor 58 detects, for example, the pressure in the flow path 60 that connects the discharge port 25a of the hydraulic pump 25 and the accumulator 26.

The relay controller 59 is composed of a CPU, a RAM, a ROM, an input/output interface and the like. The relay controller 59 controls the pump relay 57 based on the detection value of the pressure sensor 58.

Specifically, the relay controller 59 controls the pump relay 57 to be in the ON state (closed state) when the pressure of the accumulator 26 is equal to or lower than the lower limit set pressure. Then, since the drive motor 35 is energized, the hydraulic pump 25 is activated, and the hydraulic oil discharged from the hydraulic pump 25 is supplied to the accumulator 26 to accumulate pressure. The lower limit set pressure is determined in advance by experiments or the like.

The relay controller 59 controls the pump relay 57 to be in an OFF state (open state) when the pressure of the accumulator 26 is equal to or higher than the upper limit set pressure. Then, since the drive motor 35 is de-energized, the operation of the hydraulic pump 25 is stopped and the hydraulic oil is not supplied from the hydraulic pump 25 to the accumulator 26. The upper limit set pressure is a value larger than the lower limit set pressure and is determined in advance by experiments or the like.

In the brake system 15 as described above, as described above, the throttle opening degree of the variable throttle valve 47 of the second flow rate control valve 29 is smaller than the throttle opening degree of the variable throttle valve 43 of the first flow rate control valve 28. Is set to be.

When the OFF signal is output from the automatic operation controller 54 to the valve relay 53 during the automatic operation of the forklift 1, the valve relay 53 is turned off and the solenoid operating unit 40 of the first electromagnetic switching valve 27 is not energized. The position of the electromagnetic switching valve 27 is the supply position 27a. Further, since the solenoid operating portion 52 of the second electromagnetic switching valve 30 is energized, the position of the second electromagnetic switching valve 30 is the first allowable position 30a.

Then, the hydraulic oil accumulated in the accumulator 26 is supplied to the hydraulic cylinder 24 through the first electromagnetic switching valve 27, the second electromagnetic switching valve 30, and the variable throttle valve 43 of the first flow rate control valve 28, and the hydraulic cylinder 24. The piston rod 33 pushes the brake pedal 16 against the biasing force of the spring 34. When the brake pedal 16 is pushed, the brake pedal 16 pushes the piston rod 22 of the master cylinder 19 against the urging force of the spring 23. Therefore, hydraulic oil is supplied from the master cylinder 19 to the brake device 18, and the brake device 18 is released. Operate. As a result, the forklift 1 is in a state where the mechanical brake is applied, and decelerates and stops.

At this time, since the throttle opening degree of the variable throttle valve 43 of the first flow rate control valve 28 is large, the flow rate of the hydraulic oil flowing through the first flow rate control valve 28 is large and the operating speed of the piston rod 33 of the hydraulic cylinder 24 is high. Therefore, in addition to the braking by regeneration, the action of the mechanical brake is added, so that the deceleration of the forklift 1 increases and the forklift 1 immediately stops. Thereby, for example, the forklift 1 can be held in a stopped state after the forklift 1 is stopped on a slope. Further, when the forklift 1 may not be completely stopped at the target stop position with only the regenerative braking by the traveling motor 7, the forklift 1 can be stopped at the target stop position by applying the action of the mechanical brake. it can.

It should be noted that the mechanical brake used to maintain the stopped state of the slope and the mechanical brake used to stop at the target position as described above are defined as normal stops to distinguish them from emergency stops. ..

When the ON signal is output from the automatic operation controller 54 to the valve relay 53, the valve relay 53 is turned on and the solenoid operating unit 40 of the first electromagnetic switching valve 27 is energized, so that the position of the first electromagnetic switching valve 27 is changed. Switches from the supply position 27a to the return position 27b. Further, since the solenoid operating portion 52 of the second electromagnetic switching valve 30 is energized, the position of the second electromagnetic switching valve 30 is the first allowable position 30a.

Then, the hydraulic oil in the hydraulic cylinder 24 returns to the tank 36 through the check valve 46 of the first flow control valve 28, the second electromagnetic switching valve 30, and the first electromagnetic switching valve 27. Therefore, the pressing of the brake pedal 16 by the piston rod 33 of the hydraulic cylinder 24 is released, and the pressing of the piston rod 22 of the master cylinder 19 by the brake pedal 16 is released, so that hydraulic oil is supplied from the master cylinder 19 to the brake device 18. Therefore, the braking device 18 does not operate. As a result, the forklift 1 is in a state where the mechanical brake is released.

Further, when an abnormality or the like occurs while the forklift 1 is traveling, and the emergency stop button 56 is operated, the contactor 41 shuts off the main power supply 42. Therefore, since the energization of the solenoid operating portion 40 of the first electromagnetic switching valve 27 is forcibly released, the position of the first electromagnetic switching valve 27 is the supply position 27a. Moreover, since the energization of the solenoid operating portion 52 of the second electromagnetic switching valve 30 is forcibly released, the position of the second electromagnetic switching valve 30 switches from the first allowable position 30a to the second allowable position 30b.

Then, the hydraulic oil accumulated in the accumulator 26 is supplied to the hydraulic cylinder 24 through the first electromagnetic switching valve 27, the second electromagnetic switching valve 30, and the variable throttle valve 47 of the second flow rate control valve 29, and the hydraulic cylinder 24 is discharged. The piston rod 33 pushes the brake pedal 16. As a result, the forklift 1 is in the state where the mechanical brake is applied as described above, and decelerates and stops.

At this time, since the throttle opening degree of the variable throttle valve 47 of the second flow rate control valve 29 is small, the flow rate of the hydraulic oil flowing through the second flow rate control valve 29 is small and the operating speed of the piston rod 33 of the hydraulic cylinder 24 is low. Therefore, since the action of the mechanical brake is reduced, the deceleration of the forklift truck 1 becomes low, and the forklift truck 1 stops slowly. As a result, even when the luggage W is loaded on the fork 12, the forklift 1 can be stably stopped with the luggage W hardly moving. However, due to the action of the mechanical brake, the forklift 1 can be stopped more quickly than the brake using only the regenerative brake.

In addition, the mechanical brake used for emergency stop by operating the emergency stop button 56, or the mechanical brake used for emergency stop when the forklift 1 detects an abnormality, It will be an emergency stop.

As described above, in the present embodiment, when the forklift 1 is normally stopped, when the valve relay 53 is opened, the solenoid operation unit 40 of the first electromagnetic switching valve 27 is de-energized, so that the first electromagnetic switching is performed. The position of the valve 27 becomes the supply position 27a and the solenoid operating portion 52 of the second electromagnetic switching valve 30 is energized, so that the position of the second electromagnetic switching valve 30 becomes the first allowable position 30a. Therefore, the hydraulic oil from the accumulator 26 is supplied to the hydraulic cylinder 24 through the first flow rate control valve 28, and the brake pedal 16 is pressed by the hydraulic cylinder 24, so that the mechanical brake is applied to the forklift 1. On the other hand, when the forklift 1 is in an emergency stop, the main power supply 42 is shut off, so that the solenoid operating portion 40 of the first electromagnetic switching valve 27 is de-energized, so that the position of the first electromagnetic switching valve 27 is changed to the supply position 27a. At the same time, since the main power supply 42 is cut off, the solenoid operating portion 52 of the second electromagnetic switching valve 30 is de-energized, and the position of the second electromagnetic switching valve 30 becomes the second allowable position 30b. Therefore, the hydraulic oil from the accumulator 26 is supplied to the hydraulic cylinder 24 through the second flow control valve 29, and the brake pedal 16 is pressed by the hydraulic cylinder 24, so that the mechanical brake is applied to the forklift 1.

Here, by making the opening of the second flow control valve 29 smaller than the opening of the first flow control valve 28, the flow rate of the hydraulic oil flowing through the second flow control valve 29 flows through the first flow control valve 28. Less than the flow rate of hydraulic oil. Therefore, during an emergency stop in which the hydraulic oil flows through the second flow control valve 29, the operating speed of the hydraulic cylinder 24 becomes lower than in the normal stop in which the hydraulic oil flows through the first flow control valve 28, so the deceleration of the forklift 1 is reduced. Becomes lower. This makes it possible to stop the forklift 1 more slowly during an emergency stop than during a normal stop. As a result, at the time of emergency stop, the forklift 1 loaded with the luggage W can be stably stopped.

In the present embodiment, the hydraulic oil from the accumulator 26 is supplied to the hydraulic cylinder 24 through the first flow rate control valve 28 without passing through the second flow rate control valve 29 during normal stop, and during the emergency stop. The hydraulic oil from No. 1 is supplied to the hydraulic cylinder 24 through the second flow rate control valve 29 without passing through the first flow rate control valve 28. Therefore, it becomes easy to adjust the degree of application of the mechanical brake during normal stop and during emergency stop.

Further, in the present embodiment, since the three-way valve is used as the first electromagnetic switching valve 27 and the second electromagnetic switching valve 30, the number of parts of the first electromagnetic switching valve 27 and the second electromagnetic switching valve 30 is one each. I'm done. Therefore, the configurations of the first electromagnetic switching valve 27 and the second electromagnetic switching valve 30 can be simplified.

FIG. 3 is a schematic configuration diagram showing a modified example of the brake system shown in FIG. In FIG. 3, the brake system 15 of the present modified example is replaced with a first electromagnetic switching valve 70 and a second electromagnetic switching valve 71 instead of the first electromagnetic switching valve 27 and the second electromagnetic switching valve 30 in the first embodiment. Equipped with.

The first electromagnetic switching valve 70 has an opening/closing valve 72 arranged between the accumulator 26 and the hydraulic cylinder 24, and an opening/closing valve 73 arranged between the tank 36 and the hydraulic cylinder 24. The on-off valves 72 and 73 are non-leakage type solenoid valves.

The on-off valve 72 is switched between an open position 72a that allows the supply of hydraulic oil from the accumulator 26 to the hydraulic cylinder 24 and a closed position 72b that blocks the supply of hydraulic oil from the accumulator 26 to the hydraulic cylinder 24. .. The on-off valve 73 is switched to either an open position 73a that allows the return of the hydraulic oil from the hydraulic cylinder 24 to the tank 36, or a closed position 73b that blocks the return of the hydraulic oil from the hydraulic cylinder 24 to the tank 36. ..

The open position 72a of the open/close valve 72 and the closed position 73b of the open/close valve 73 constitute a supply position for supplying the hydraulic oil from the accumulator 26 to the hydraulic cylinder 24 in the first electromagnetic switching valve 70. The closed position 72b of the open/close valve 72 and the open position 73a of the open/close valve 73 constitute a return position for returning the hydraulic oil from the hydraulic cylinder 24 to the tank 36 in the first electromagnetic switching valve 70.

A spring 74 is provided on the open position 72a side of the opening/closing valve 72. A solenoid operating unit 75 is provided on the closed position 72b side of the opening/closing valve 72. The solenoid operating unit 75 is connected to the main power supply 42 via the valve relay 53 and the contactor 41. When the solenoid operating portion 75 is energized, the position of the opening/closing valve 72 becomes the closed position 72b. When the solenoid operating unit 75 is de-energized, the spring 74 causes the opening/closing valve 72 to move to the open position 72a.

A spring 76 is provided on the closed position 73b side of the opening/closing valve 73. A solenoid operating unit 77 is provided on the open position 73a side of the opening/closing valve 73. The solenoid operating unit 77 is connected to the main power source 42 via the valve relay 53 and the contactor 41. When the solenoid operating unit 77 is energized, the position of the opening/closing valve 73 becomes the open position 73a. When the solenoid operating unit 77 is de-energized, the spring 76 causes the opening/closing valve 73 to move to the closed position 73b.

The solenoid operating parts 75 and 77 form a first solenoid operating part of the first electromagnetic switching valve 70.

The second electromagnetic switching valve 71 is provided between the opening/closing valve 78 arranged between the first electromagnetic switching valve 70 and the first flow rate control valve 28, and between the first electromagnetic switching valve 70 and the second flow rate control valve 29. And an on-off valve 79 arranged. The on-off valves 78 and 79 are non-leak solenoid valves.

The open/close valve 78 is located between the first electromagnetic switching valve 70 and the first flow rate control valve 28, and the open position 78a that allows the flow of hydraulic oil between the first electromagnetic switching valve 70 and the first flow rate control valve 28. To a closed position 78b that shuts off the flow of hydraulic oil. The on-off valve 79 is located between the first electromagnetic switching valve 70 and the second flow rate control valve 29, and the open position 79a that allows the flow of hydraulic oil between the first electromagnetic switching valve 70 and the second flow rate control valve 29. To a closed position 79b for shutting off the flow of hydraulic oil.

The open position 78a of the open/close valve 78 and the closed position 79b of the open/close valve 79 allow the flow of hydraulic oil between the first electromagnetic switching valve 70 and the first flow rate control valve 28 in the second electromagnetic switching valve 71, and The first permissible position that blocks the flow of hydraulic oil between the first electromagnetic switching valve 70 and the second flow rate control valve 29 is configured. The closed position 78b of the open/close valve 78 and the open position 79a of the open/close valve 79 allow the flow of hydraulic oil between the first electromagnetic switching valve 70 and the second flow rate control valve 29 in the second electromagnetic switching valve 71, and the second position. The second permissible position that blocks the flow of hydraulic oil between the first electromagnetic switching valve 70 and the first flow rate control valve 28 is configured.

A spring 80 is provided on the closed position 78b side of the opening/closing valve 78. A solenoid operating unit 81 is provided on the open position 78a side of the opening/closing valve 78. The solenoid operating unit 81 is connected to the main power source 42 via the contactor 41. When the solenoid operating portion 81 is energized, the position of the opening/closing valve 78 becomes the open position 78a. When the solenoid operating unit 81 is de-energized, the spring 80 causes the opening/closing valve 78 to move to the closed position 78b.

A spring 82 is provided on the open position 79a side of the opening/closing valve 79. A solenoid operating portion 83 is provided on the closed position 79b side of the opening/closing valve 79. The solenoid operating unit 83 is connected to the main power source 42 via the contactor 41. When the solenoid operating portion 83 is energized, the position of the opening/closing valve 79 becomes the closed position 79b. When the energization of the solenoid operating portion 83 is released, the position of the opening/closing valve 79 becomes the open position 79a by the spring 82.

The solenoid operating parts 81 and 83 form a second solenoid operating part of the second electromagnetic switching valve 71.

In the above, at the time of normal stop, the valve relay 53 is turned off, so that the solenoid operating portion 75 of the opening/closing valve 72 and the solenoid operating portion 77 of the opening/closing valve 73 are de-energized and the solenoid operating portion of the opening/closing valve 78 is released. 81 and the solenoid operating portion 83 of the on-off valve 79 are energized. Therefore, the position of the open/close valve 72 becomes the open position 72a, the position of the open/close valve 73 becomes the closed position 73b, the position of the open/close valve 78 becomes the open position 78a, and the position of the open/close valve 79 becomes the closed position 79b. Then, the hydraulic oil accumulated in the accumulator 26 is supplied to the hydraulic cylinder 24 through the open/close valve 72, the open/close valve 78, and the variable throttle valve 43 of the first flow control valve 28. For this reason, the forklift 1 is immediately in the state where the mechanical brake is applied as described above.

From that state, when the valve relay 53 is turned on and the solenoid operating portion 75 of the open/close valve 72 and the solenoid operating portion 77 of the open/close valve 73 are energized, the position of the open/close valve 72 is changed from the open position 72a to the closed position. 72b, and the position of the on-off valve 73 switches from the closed position 73b to the open position 73a. Then, the hydraulic oil in the hydraulic cylinder 24 returns to the tank 36 through the check valve 46, the opening/closing valve 78, and the opening/closing valve 73 of the first flow control valve 28. Therefore, the forklift 1 is in the state where the mechanical brake is released as described above.

On the other hand, at the time of emergency stop, since the main power supply 42 is shut off, the solenoid operating portion 75 of the opening/closing valve 72 and the solenoid operating portion 77 of the opening/closing valve 73 are de-energized, and the solenoid operating portion 81 of the opening/closing valve 78 and the opening/closing are opened. The energization of the solenoid operating portion 83 of the valve 79 is released. Therefore, the position of the opening/closing valve 72 becomes the opening position 72a, the position of the opening/closing valve 73 becomes the closing position 73b, the position of the opening/closing valve 78 switches from the opening position 78a to the closing position 78b, and the position of the opening/closing valve 79 becomes the closing position. It switches from 79b to the open position 79a. Then, the hydraulic oil accumulated in the accumulator 26 is supplied to the hydraulic cylinder 24 through the on-off valve 72, the on-off valve 79 and the variable throttle valve 47 of the second flow rate control valve 29. Therefore, the forklift 1 is in a state where the mechanical brake is slowly applied as described above.

In this modification, as the opening/closing valves 72, 73 forming the first electromagnetic switching valve 70 and the opening/closing valves 78, 79 forming the second electromagnetic switching valve 71, ordinary inexpensive electromagnetic valves can be used. Therefore, the costs of the first electromagnetic switching valve 70 and the second electromagnetic switching valve 71 can be suppressed.

FIG. 4 is a schematic configuration diagram showing a brake system for an industrial vehicle according to the second embodiment of the present invention. In FIG. 4, the brake system 15 of the present embodiment includes a load sensor 90 and a valve relay 91 in addition to the configuration of the first embodiment described above.

The load sensor 90 is a load detection unit that detects the load of the cargo W loaded on the fork 12 of the forklift 1 (the load of the forklift 1). As the load sensor 90, for example, a pressure sensor that detects the pressure of the lift cylinder 13 is used.

The valve relay 91 is connected between the solenoid operating unit 52 of the second electromagnetic switching valve 30 and the contactor 41. The valve relay 91 is a second switch unit that switches the power output from the main power supply 42. The valve relay 91 is controlled by the automatic driving controller 54. The automatic driving controller 54 constitutes a control unit that controls the valve relay 91 based on the detection value of the load sensor 90.

FIG. 5 is a flowchart showing a control processing procedure of the valve relay 91 executed by the automatic driving controller 54. In FIG. 5, the automatic driving controller 54 first acquires the detection value of the load sensor 90 (step S101).

Then, the automatic driving controller 54 determines whether the load of the forklift 1 detected by the load sensor 90 is equal to or more than a threshold value (step S102). At this time, the threshold value may be a value for determining whether or not the load W is loaded on the fork 12, or a value for determining whether or not the load W having a predetermined weight or more is loaded on the fork 12. Good.

When the automatic operation controller 54 determines that the load of the forklift 1 is not greater than or equal to the threshold, that is, the load of the forklift 1 is less than the threshold, it controls the valve relay 91 to close (turn on) (step S103). .. As a result, the solenoid operating portion 52 of the second electromagnetic switching valve 30 is energized, and the position of the second electromagnetic switching valve 30 becomes the first allowable position 30a.

When the automatic operation controller 54 determines that the load of the forklift 1 is greater than or equal to the threshold value, it controls the valve relay 91 to open (turn off) (step S104). As a result, the solenoid operating portion 52 of the second electromagnetic switching valve 30 is de-energized, and the position of the second electromagnetic switching valve 30 is switched from the first allowable position 30a to the second allowable position 30b.

In this embodiment as described above, by controlling the valve relay 91 so that the solenoid operating portion 52 of the second electromagnetic switching valve 30 is de-energized, the second electromagnetic switching valve 30 moves from the first allowable position 30a to the first allowable position 30a. 2 Switch to the allowable position 30b. Therefore, the hydraulic oil from the accumulator 26 is supplied to the hydraulic cylinder 24 through the second flow rate control valve 29 even during the normal stop, so that the forklift 1 is mechanically braked in the same manner as during the emergency stop. You can

Further, in the present embodiment, the valve relay 91 is opened when the load load of the forklift 1 is equal to or more than the threshold value. Accordingly, since the solenoid operating portion 52 of the second electromagnetic switching valve 30 is de-energized, the second electromagnetic switching valve 30 switches from the first allowable position 30a to the second allowable position 30b. As a result, the forklift 1 loaded with the luggage W can be stably stopped even when the forklift 1 is normally stopped.

FIG. 6 is a schematic configuration diagram showing a modified example of the brake system shown in FIG. In FIG. 6, a brake system 15 of the present modified example is replaced with the first electromagnetic switching valve 27 and the second electromagnetic switching valve 30 in the second embodiment described above, and the first electromagnetic switching valve 70 and the second electromagnetic switching valve described above are used. The valve 71 is provided. Other configurations are similar to those of the second embodiment.

The present invention is not limited to the above embodiment. For example, in the above modification, the opening/closing valve 79 is arranged between the first electromagnetic switching valve 70 and the second flow rate control valve 29, but such an opening/closing valve 79 may be omitted. In this case, the hydraulic oil from the accumulator 26 is supplied to the hydraulic cylinder 24 through the first flow rate control valve 28 and the second flow rate control valve 29 during the normal stop. At the time of emergency stop, the hydraulic oil from the accumulator 26 is supplied to the hydraulic cylinder 24 through the second flow control valve 29, as in the above embodiment.

In the above embodiment, the first flow rate control valve 28 has the variable throttle valve 43 and the second flow rate control valve 29 has the variable throttle valve 47. It is not limited to the throttle valves 43 and 47, and may be a fixed throttle valve if fine adjustment of the deceleration is unnecessary.

Further, in the above-described embodiment, the brake oil 16 is pressed by the hydraulic oil accumulated in the accumulator 26 being supplied to the hydraulic cylinder 24, but such an accumulator 26 may be omitted, and the hydraulic pump The brake pedal 16 may be pressed by supplying hydraulic oil discharged from 25 to the hydraulic cylinder 24. In this case, the hydraulic pump 25 serves as a hydraulic pressure source.

Further, the brake system 15 of the above-described embodiment is mounted on the forklift 1 that performs automatic operation, but the forklift may be switchable between manual operation and automatic operation by an operator. In this case, the hydraulic cylinder 24 is arranged at a position where it does not hinder the operator's depression of the brake pedal 16.

Further, the brake system 15 of the above embodiment is mounted on the electric forklift 1 driven by the electric power of the battery 9, but the present invention is also applicable to an engine forklift driven by an engine. ..

Further, the brake system 15 of the above-described embodiment is mounted on the forklift 1, but the present invention is also applicable to industrial vehicles other than forklifts (for example, towing tractors) as long as the brake pedal is provided. ..

DESCRIPTION OF SYMBOLS 1... Forklift (industrial vehicle), 15... Brake system, 16... Brake pedal, 17... Brake unit, 24... Hydraulic cylinder, 26... Accumulator (hydraulic power source), 27... 1st electromagnetic switching valve, 27a... Supply position, 27b ... Return position, 28... First flow rate control valve, 29... Second flow rate control valve, 30... Second electromagnetic switching valve, 30a... First allowable position, 30b... Second allowable position, 36... Tank, 40... Solenoid operation Part (first solenoid operation part), 42... Main power supply (power supply), 52... Solenoid operation part (second solenoid operation part), 53... Valve relay (first switch part), 54... Automatic operation controller (control part) , 70... First electromagnetic switching valve, 71... Second electromagnetic switching valve, 72a... Open position (supply position), 72b... Closed position (return position), 73a... Open position (return position), 73b... Closed position (supply) Position), 75, 77... Solenoid operating part (first solenoid operating part), 78a... Open position (first permissible position), 78b... Closed position (second permissible position), 79a... Open position (second permissible position) , 79b... Closed position (first allowable position), 81, 83... Solenoid operating part (second solenoid operating part), 90... Load sensor (load detecting part), 91... Valve relay (second switch part).

Claims (4)

In a brake system for an industrial vehicle, which operates a brake unit by pressing a brake pedal provided in the industrial vehicle, to brake the industrial vehicle,
A hydraulic source that supplies hydraulic oil,
A hydraulic cylinder that is driven by hydraulic oil from the hydraulic source and presses the brake pedal,
Between the hydraulic source and the tank and the hydraulic cylinder, a supply position for supplying the hydraulic oil from the hydraulic source to the hydraulic cylinder, and a return position for returning the hydraulic oil from the hydraulic cylinder to the tank. A first electromagnetic switching valve that is switched to either
A first flow rate control valve and a second flow rate control valve that are arranged in parallel between the first electromagnetic switching valve and the hydraulic cylinder and control the flow rate of the hydraulic oil supplied from the hydraulic pressure source to the hydraulic cylinder; ,
It is arranged between the first electromagnetic switching valve and the first flow control valve and the second flow control valve, and allows the flow of hydraulic oil between the first electromagnetic switching valve and the first flow control valve. A first allowable position and a flow of hydraulic oil between the first electromagnetic switching valve and the second flow rate control valve, and an operation between the first electromagnetic switching valve and the first flow rate control valve. A second electromagnetic switching valve that is switched to either a second allowable position that blocks the flow of oil,
The first electromagnetic switching valve has a first solenoid operating unit connected to a power source,
When the first solenoid operating unit is energized, the position of the first electromagnetic switching valve becomes the return position,
When the first solenoid operating unit is de-energized, the position of the first electromagnetic switching valve becomes the supply position,
A first switch unit is connected between the first solenoid operating unit and the power source,
The second electromagnetic switching valve has a second solenoid operating unit connected to the power source,
When the second solenoid operating unit is energized, the position of the second electromagnetic switching valve becomes the first allowable position,
When the second solenoid operating unit is de-energized, the position of the second electromagnetic switching valve becomes the second allowable position,
A brake system for an industrial vehicle, wherein an opening of the second flow control valve is smaller than an opening of the first flow control valve. The first allowable position allows the flow of hydraulic oil between the first electromagnetic switching valve and the first flow rate control valve, and operates between the first electromagnetic switching valve and the second flow rate control valve. The brake system for an industrial vehicle according to claim 1, wherein the brake system is located at a position where the flow of oil is interrupted. The brake system for an industrial vehicle according to claim 1, wherein a second switch unit is connected between the second solenoid operating unit and the power source. A load detection unit for detecting a load load of the industrial vehicle,
The brake system for an industrial vehicle according to claim 3, further comprising: a control unit that controls to open the second switch unit when the load load detected by the load detection unit is equal to or greater than a threshold value.

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