JPH08188400A - Cooling method for hydraulic pump-motor in cargo-handling industrial vehicle and hydraulic circuit control device used in the method - Google Patents

Abstract

PURPOSE: To enable to use a motor with standard specification by draining pressured oil from a oil pressure pump to a tank when a hydraulic cylinder equipped in an industrial vehicle for loading is stopped, by rotating a motor in a light loading state for the pump and by cooling the motor itself with a fan rotated by the motor. CONSTITUTION: A control valve unit 29 controlling the operation of a lift cylinder 17 and a tilt cylinder 19 is disposed in a hydraulic circuit 21. This control valve unit 29 is equipped with a first control valve controlling the operation of the lift cylinder 17 and a second control valve controlling the operation of the tilt cylinder 19 in a loading industrial vehicle and unitizes them. Then, while either the lift cylinder 17 or the tilt cylinder 19 is stopped, even if a pressure sensor 23 is operated, a solenoid 25S is tuned on, an open and close valve 25 is opened so that the pressured oil in the hydraulic circuit 21 is drained to a tank T, an oil pressure pump P is made to become a light loading state to rotate a motor. The motor M itself can be cooled by wind sent from a fan F caused by the motor M to improve the safety.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cooling a motor for a hydraulic pump in a cargo handling industrial vehicle such as a forklift truck, and a hydraulic circuit control device used in the method.

More specifically, when a hydraulic cylinder provided in an industrial vehicle for cargo handling is stopped, the hydraulic pump is brought into a light load state, and the motor is rotated at a light load to forcibly cool the motor itself by a fan provided in the motor. The present invention relates to a method and a hydraulic circuit control device used in the method.

[0003]

2. Description of the Related Art As a prior art example considered to be related to the present invention, there is JP-A-2-33098. In this prior art example, a forklift is shown as an industrial vehicle for cargo handling.

In the above prior art example, as shown in FIG. 3, a mast 3 is provided on the front side of the vehicle body 1, and the mast 3 is provided.
The fork 5 is vertically movable. A tilt cylinder 7 for swinging the mast 3 back and forth is provided between the main body 1 and the mast 3, and a lift cylinder 9 for vertically moving the fork 5 is provided on the mast 3.

Further, the tilt cylinder 7 is attached to the main body 1.
And an operating lever 1 for operating the lift cylinder 9.
1, 13 are provided respectively, and the operation levers 11, 1 are provided.
A switch (not shown) for detecting that the operation levers 11 and 13 are operated and driving the motor for the hydraulic pump is provided at a position close to the position 3.

With the above structure, in the prior art example, when the operation levers 11 and 13 are operated, the switches provided in proximity to the respective operation levers are operated, the motor is driven and the hydraulic pump is driven, and the corresponding action is taken. Hydraulic cylinder (one or both of tilt cylinder 7 and lift cylinder 9)
Is operated.

When the hydraulic cylinder reaches the stroke end, the driving of the motor for the hydraulic pump is stopped.

[0008]

In the conventional structure such as the prior art, the driving of the motor for the hydraulic pump is stopped when the hydraulic cylinder reaches the stroke end, so that the heat generation of the motor is not suppressed. it can. However, since there is no choice but to rely on natural cooling for cooling the motor, when using a motor in a sealed mode such as dustproof specifications, the natural cooling effect is small, so consider the heat resistance condition and use it as a standard. However, there is a problem in that a motor having a higher output than the existing one must be used, resulting in higher cost.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional problems as described above, and the invention described in the first item is a motor connected to a hydraulic pump provided in an industrial vehicle for cargo handling. As a cooling method, when the hydraulic cylinder provided in the industrial vehicle for cargo handling is stopped, the pressure oil from the hydraulic pump is drained to the tank, the hydraulic pump is set to a light load state, the motor is rotated, and the motor is rotated. Is a method for cooling a motor for a hydraulic pump in a cargo handling industrial vehicle in which the motor itself is cooled by a fan.

In the method according to the second aspect of the present invention, the drain of the pressure oil from the hydraulic pump to the tank controls the opening / closing of the opening / closing valve branched and connected to the hydraulic circuit connecting the hydraulic pump and the hydraulic cylinder. The control of the opening and closing of the on-off valve is performed based on the output signal of the switch operated when operating the operation lever for operating the hydraulic cylinder and the output signal of the pressure sensor that detects the pressure of the hydraulic circuit. A method for cooling a motor for a hydraulic pump in an industrial vehicle.

The hydraulic circuit control device for an industrial vehicle for cargo handling according to the invention as set forth in claim 3 controls the operation of the hydraulic cylinder in a hydraulic circuit connecting a hydraulic cylinder and a hydraulic pump provided in the industrial vehicle for cargo handling. And a switch that is operated by operating an operation lever provided in the control valve, and a pressure sensor that operates when the pressure in the hydraulic circuit becomes a predetermined pressure or more is connected to the hydraulic circuit. An opening / closing valve is provided in a branch path branched and connected to the hydraulic circuit, and an opening / closing valve control unit is provided to control opening / closing of the opening / closing valve based on an output signal of the switch and an output signal of a pressure sensor. When the hydraulic cylinder is stopped, the opening / closing valve is opened to bring the hydraulic pump into a light load state, and the motor for rotationally driving the hydraulic pump is rotated in the light load state. The fan with the said motor is made as a structure for cooling the motor itself.

In the hydraulic circuit control device for an industrial vehicle for cargo handling according to the invention as set forth in claim 4, the on-off valve control section is:
The configuration includes an operation confirmation unit that determines whether or not the operation lever has been operated when the pressure sensor operates.

[0013]

According to the invention of the first aspect, a method of cooling a motor connected to a hydraulic pump provided in an industrial vehicle for cargo handling is provided, and when the hydraulic cylinder provided in the industrial vehicle for cargo handling is stopped, Since it is a method of cooling a hydraulic pump motor in a cargo handling industrial vehicle in which pressure oil is drained to a tank and a hydraulic pump is put in a light load state to rotate the motor, and the motor is cooled by a fan rotated by the motor, The motor is in a state in which heat generation is small by rotating in a light load state in which a hydraulic pump in a light load state and a fan included in the motor are rotationally driven, and is forcibly cooled by cooling air blown by the fan. There is something.

Therefore, even if the motor itself is in a high temperature state due to the heat generated at the time of high load due to the operation of the hydraulic cylinder, it will be immediately cooled by the cooling air when the hydraulic cylinder is stopped, and the motor can be effectively cooled. It is possible to use the standard specification motor.

In the method according to the second aspect of the present invention, the drain of the pressure oil from the hydraulic pump to the tank controls the opening / closing of the opening / closing valve branched and connected to the hydraulic circuit connecting the hydraulic pump and the hydraulic cylinder. The control of the opening and closing of the on-off valve is performed based on the output signal of the switch operated when operating the operation lever for operating the hydraulic cylinder and the output signal of the pressure sensor that detects the pressure of the hydraulic circuit. Since this is a method of cooling a motor for a hydraulic pump in an industrial vehicle, the stop signal of the hydraulic cylinder is confirmed by the output signal of the pressure sensor, and then the opening / closing valve is opened to bring the hydraulic pump into a light load state.

Therefore, the on-off valve is not opened during the operation of the hydraulic cylinder, and it is easy to automatically switch the hydraulic pump to the light load state.

The hydraulic circuit control device for an industrial vehicle for cargo handling according to the invention as set forth in claim 3 controls the operation of the hydraulic cylinder in a hydraulic circuit connecting a hydraulic cylinder and a hydraulic pump provided in the industrial vehicle for cargo handling. And a switch that is operated by operating an operation lever provided in the control valve, and a pressure sensor that operates when the pressure in the hydraulic circuit becomes a predetermined pressure or more is connected to the hydraulic circuit. An opening / closing valve is provided in a branch path branched and connected to the hydraulic circuit, and an opening / closing valve control unit is provided to control opening / closing of the opening / closing valve based on an output signal of the switch and an output signal of a pressure sensor. When the hydraulic cylinder is stopped, the opening / closing valve is opened to bring the hydraulic pump into a light load state, and the motor for rotationally driving the hydraulic pump is rotated in the light load state. The fan with the said motor is made as a structure for cooling the motor itself.

Therefore, after the switch is turned on by operating the operating lever to drive the motor and drive the hydraulic pump to supply the hydraulic pressure to the hydraulic cylinder, the hydraulic cylinder reaches the stroke end and the pressure in the hydraulic cylinder reaches a predetermined level. When the pressure rises above the pressure, the pressure sensor operates, the on-off valve is opened, and the pressure in the hydraulic circuit is drained, so that the hydraulic pump is in a light load state.

Therefore, when the hydraulic pump has a light load, the motor also has a light load, so that heat generation of the motor is suppressed and
It is forcibly cooled by the cooling air blown by the fan provided in the motor, so that the motor can be effectively cooled.

Therefore, the damage due to heat generation of the motor can be prevented, and the standard specification motor can be used.

In the hydraulic circuit control device for the industrial vehicle for cargo handling according to the invention as set forth in claim 4, the on-off valve control section is:
The configuration includes an operation confirmation unit that determines whether or not the operation lever has been operated when the pressure sensor operates.

Therefore, when the pressure sensor operates despite the operation lever not being operated, it can be recognized as a malfunction. Therefore, in this case, the safety can be improved by investigating the cause of the malfunction.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings. Since the overall construction of a forklift as an industrial vehicle for cargo handling is the same as the conventional configuration described above, the entire industrial vehicle for cargo handling is described. The detailed description of the dynamic configuration is omitted.

In FIG. 1, P is a hydraulic pump connected to a motor M. A fan F for blowing cooling air to the motor M itself is appropriately interlocked with the motor M. A power transistor 17 that controls the rotation of the motor M is connected to the motor drive circuit that connects the motor M and the power supply 15.

A pressure sensor 23 for detecting the pressure in the hydraulic circuit 21 is connected to the hydraulic circuit 21 which connects the hydraulic pump P to the lift cylinder 17 and the tilt cylinder 19 in the forklift. Furthermore, the hydraulic circuit 2
An opening / closing valve 25 and a relief valve 27 are branched and connected to 1.

The pressure sensor 23 is activated when the pressure in the hydraulic circuit 21 exceeds a predetermined pressure and is turned on.
(Or OFF) signal is output.

The on-off valve 25 normally has the circuit closed, and operates to open when the solenoid 25S is excited to drain the pressure oil of the hydraulic circuit 21 to the tank T.

The relief valve 27 is opened to drain the pressure oil in the hydraulic circuit 21 to the tank T when the pressure in the hydraulic circuit 21 rises above the predetermined pressure and becomes equal to or higher than a preset pressure. It functions as a safety valve.

A control valve unit 29 for controlling the operations of the lift cylinder 17 and the tilt cylinder 9 is arranged in the hydraulic circuit 21. The control valve unit 29 is a unit of a first control valve (not shown) for controlling the operation of the lift cylinder 17 and a second control valve (not shown) for controlling the operation of the tilt cylinder 19. Is.

The first control valve for controlling the operation of the lift cylinder 17 and the second control valve for controlling the operation of the tilt cylinder 19 are publicly known as shown in, for example, the preceding examples, Detailed description of the configurations of the first and second control valves is omitted.

The first control valve is provided with an operating lever 31 for operating the first control valve to operate the lift cylinder 17. This operation lever 31 is used for the lift cylinder 17
Can be operated in three positions, namely, a first position for controlling to raise, a second position for controlling to lower, and a neutral position. The operation of the operation lever 31 is detected by the switch 33 provided near the operation lever 31.

The switch 33 operates to detect only when the operating lever 31 is operated to the first position.
The detection signal of the switch 33 is input to the control device 35.

That is, when the operation lever 31 is operated to the first position (for example, when it is operated upward in FIG. 1),
The switch 33 operates and the motor M is started. And then
The hydraulic pump P is driven to supply pressure oil to the lift cylinder 17, so that the lift cylinder 17 moves up.

The pressure oil is supplied to the lift cylinder 17 through a check valve (not shown), and the lift cylinder 17 is held in the raised state unless the operating lever 31 is moved to the second position. It is something.

When the operation lever 31 is operated to the second position (for example, downward operation in FIG. 1), the lift cylinder 17 is lowered by its own weight, and the pressure oil is discharged to the tank T.

Second for controlling the operation of the tilt cylinder 19
The control valve is provided with an operating lever 37, and a switch 39 for detecting that the operating lever 37 has been operated from the neutral position to the first and second positions. The detection signal of the switch 39 is input to the control device 35.

The control device 35 controls the pressure sensor 23.
And the opening and closing of the motor M and the on-off valve 25 based on the input signals from the switches 33 and 39.

Next, the operation of the above configuration will be described with reference to the flow chart shown in FIG.

In step S1, the lift cylinder 1
The operating lever 31 of the first control valve for controlling the
It is determined whether the switch 33 has been operated to the position and the switch 33 has been actuated. If YES, the first flag R0 is set to 1,
In the case of NO, the first flag R0 is set to 0.

When the first flag R0 is 1, a signal is output from the control device 35 to the power transistor 17, so that the power transistor 17 becomes conductive and the motor M is turned on.
Is started. The hydraulic pump P is driven by starting the motor M, and the pressure oil from the hydraulic pump P is supplied to the lift cylinder 17 via the hydraulic circuit 21 and the first control valve. Therefore, the lift cylinder 17 is operated to move up.

Next, in step S2, it is determined whether or not the switch 39 has been operated by operating the operating lever 37 of the second control valve for controlling the tilt cylinder 19. If the above determination is YES, the second flag T0 is set to 1, and if the determination is NO, the second flag T0 is set to 0.

When the switch 39 is operated and the second flag T0 becomes 1, and the motor M is not driven, the motor M is started and the hydraulic pump P is driven. Then, the tilt cylinder 19 operates leftward or rightward in FIG. 1 in accordance with the operating direction of the operating lever 37.

As described above, after activating at least one of the lift cylinder 17 and the tilt cylinder 19, the pressure sensor 23 is turned on (or turned off) in step S3.
It is determined whether or not it has operated.

That is, when the lift cylinder 17 and the tilt cylinder 19 are operated by operating the operation levers 31 and 37 of the first and second control valves, and the lift cylinder 17 and the tilt cylinder 19 reach the stroke end, the hydraulic circuit. The pressure sensor 23 is activated when the hydraulic pressure in 21 gradually rises and becomes equal to or higher than a predetermined pressure.

Therefore, when the pressure sensor 23 operates, the hydraulic cylinder to be controlled (the lift cylinder 17
Alternatively, one or both of the tilt cylinders 19 have reached the stroke end and are in a stopped state.

If NO at step S3, the process returns to step S1, and if YES, the process proceeds to step S4.

In step S4, it is determined whether or not the first and second flags R0 and T0 are 1 prior to the opening operation of the opening / closing valve 25. That is, when both the operation levers 31 and 37 are not operated, and the pressure sensor 23 is turned on in a state where both the first and second flags R0 and T0 are not 1, the pressure sensor 23 or the hydraulic circuit is turned on. Two
1 can be recognized as having an abnormality.

Therefore, in this case, the pressure sensor 2
The safety can be improved by confirming the cause that the 3 is turned on.

If NO in step S4, the operation levers 31 and 39 are not operated, so the process returns to step S1. If YES, operating lever 3
At least one of 1 and 39 is operated, and the hydraulic cylinder to be operated reaches the stroke end and is in a stopped state. Therefore, the process proceeds to step S5, and the solenoid 25S of the on-off valve 25 is turned on.

When the solenoid 25S is turned on, the opening / closing valve 25 is opened and the pressure oil in the hydraulic circuit 21 is drained to the tank T, so that the load on the hydraulic pump P becomes a light load. Therefore, the motor M that drives the hydraulic pump P also has a light load, heat generation of the motor M is suppressed, and the motor M is forcibly cooled by the cooling air that is driven by the motor M and blown from the fan F. Become.

Therefore, even if the temperature of the motor M rises due to heat generation of the motor M when the load of the hydraulic pump P is large due to the driving of the hydraulic cylinder or the like, the state of light load is immediately established after the hydraulic cylinder is stopped. Since the fan is forcibly cooled, it is possible to effectively cool the motor M and prevent the motor M from reaching a high temperature.

Therefore, as the motor M, a dustproof type motor of standard specifications can be used, and the motor M has an inexpensive structure without using a motor having a larger output.

When the motor M is driven with a light load as described above to perform the forced cooling, it is determined in step S6 whether or not the switch 33 has been turned ON by the operation of the operation lever 31, and if YES, Is the third flag R
1 is set to 1, and 0 is set to NO.

Next, in step S7, the operating lever 3
7 is operated to determine whether or not the switch 39 has been turned ON. If YES, the third flag T1 is set to 1, and
If NO, set to 0.

Then, in step S8, the exclusive OR (XO) of the first flag R0 and the third flag R1 is performed.
R) and the exclusive OR of the second flag T0 and the fourth flag T1 and the logical OR (0R) of both exclusive ORs, and the result is not 1. Since the current state is maintained, the process returns to step S5, and the open / close valve 25 is open.

If the calculation result in step S8 is 1, it means that at least one of the operation levers 31 and 37 has been newly operated in step S6 or step S7. The solenoid 25S is turned off and the on-off valve 25 is closed. Then, the process returns to step S1 and the above-described operation is repeated.

[0057]

As can be understood from the above description of the embodiments, the invention described in the first item is a cooling method for a motor connected to a hydraulic pump provided in an industrial vehicle for cargo handling.
At the time of stopping the hydraulic cylinder provided in the above cargo handling industrial vehicle,
A method for cooling a motor for a hydraulic pump in a cargo handling industrial vehicle in which pressure oil from the hydraulic pump is drained to the hydraulic pump to cause a light load to rotate the motor, and the motor is cooled by a fan rotated by the motor. Therefore, the motor is in a state of less heat generation by rotating in a light load state in which the fan provided in the hydraulic pump and the motor of a light load state is rotationally driven, and is forced by the cooling air blown by the fan. It is cooled to.

Therefore, even if the motor itself is in a high temperature state due to heat generated at high load due to the operation of the hydraulic cylinder, it is immediately cooled by the cooling air when the hydraulic cylinder is stopped, so that the motor can be effectively cooled. It is possible to use the standard specification motor.

In the method according to the second aspect of the present invention, the drain of the pressure oil from the hydraulic pump to the tank controls the opening / closing of the opening / closing valve branched and connected to the hydraulic circuit connecting the hydraulic pump and the hydraulic cylinder. The control of the opening and closing of the on-off valve is performed based on the output signal of the switch operated when operating the operation lever for operating the hydraulic cylinder and the output signal of the pressure sensor that detects the pressure of the hydraulic circuit. Since this is a method of cooling a motor for a hydraulic pump in an industrial vehicle, the stop signal of the hydraulic cylinder is confirmed by the output signal of the pressure sensor, and then the opening / closing valve is opened to bring the hydraulic pump into a light load state.

Therefore, the on-off valve is not opened during the operation of the hydraulic cylinder, and it is easy to automatically switch the hydraulic pump to the light load state and forcibly cool it.

The hydraulic circuit control device for an industrial vehicle for cargo handling according to the invention of item 3 controls the operation of the hydraulic cylinder in a hydraulic circuit which connects a hydraulic cylinder and a hydraulic pump provided in the industrial vehicle for cargo handling. And a switch that is operated by operating an operation lever provided in the control valve, and a pressure sensor that operates when the pressure in the hydraulic circuit becomes a predetermined pressure or more is connected to the hydraulic circuit. An opening / closing valve is provided in a branch path branched and connected to the hydraulic circuit, and an opening / closing valve control unit is provided to control opening / closing of the opening / closing valve based on an output signal of the switch and an output signal of a pressure sensor. When the hydraulic cylinder is stopped, the opening / closing valve is opened to bring the hydraulic pump into a light load state, and the motor for rotationally driving the hydraulic pump is rotated in the light load state. The fan with the said motor is made as a structure for cooling the motor itself.

Therefore, after the switch is turned on by operating the operation lever to drive the motor and drive the hydraulic pump to supply the hydraulic pressure to the hydraulic cylinder, the hydraulic cylinder reaches the stroke end and the pressure in the hydraulic cylinder reaches a predetermined level. When the pressure rises above the pressure, the pressure sensor operates, the on-off valve is opened, and the pressure in the hydraulic circuit is drained, so that the hydraulic pump is in a light load state.

Therefore, when the hydraulic pump has a light load, the motor also has a light load and heat generation of the motor is suppressed, and at the same time,
It is forcibly cooled by the cooling air blown by the fan provided in the motor, so that the motor can be effectively cooled.

Therefore, it is possible to prevent the motor from being damaged by heat generation and to use the motor of the standard specification.

In the hydraulic circuit control device for the industrial vehicle for cargo handling according to the invention of item 4, the on-off valve control section is
The configuration includes an operation confirmation unit that determines whether or not the operation lever has been operated when the pressure sensor operates.

Therefore, when the pressure sensor operates even though the operation lever is not operated, it can be recognized as a malfunction. Therefore, in this case, the safety can be improved by investigating the cause of the malfunction.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view of a hydraulic circuit control device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation.

FIG. 3 is an explanatory diagram of a conventional configuration.

[Explanation of symbols]

 M Motor P Hydraulic pump F Fan 17 Lift cylinder 19 Tilt cylinder 21 Hydraulic circuit 23 Pressure sensor 25 Open / close valve 31,37 Operating lever 33,39 Switch

Claims (4)

[Claims] 1. A method for cooling a motor connected to a hydraulic pump provided in a cargo handling industrial vehicle, wherein the hydraulic oil from the hydraulic pump is drained to a tank when a hydraulic cylinder provided in the cargo handling industrial vehicle is stopped. A method for cooling a motor for a hydraulic pump in a cargo handling industrial vehicle, comprising: rotating the motor with a light load on the hydraulic pump, and cooling the motor itself by a fan rotated by the motor. 2. The drain of the pressure oil from the hydraulic pump to the tank is performed by controlling the opening / closing of an opening / closing valve branched and connected to a hydraulic circuit connecting the hydraulic pump and the hydraulic cylinder, and controlling the opening / closing of the opening / closing valve. The cargo handling according to claim 1, wherein the cargo handling is performed based on an output signal of a switch that is operated when an operating lever that operates a hydraulic cylinder and an output signal of a pressure sensor that detects the pressure of the hydraulic circuit. For cooling motors for hydraulic pumps in industrial vehicles. 3. A control circuit for controlling the operation of the hydraulic cylinder is provided in a hydraulic circuit connecting a hydraulic cylinder and a hydraulic pump provided in an industrial vehicle for cargo handling, and is operated by operating an operation lever provided in the control valve. Is provided, a pressure sensor that operates when the pressure in the hydraulic circuit exceeds a predetermined pressure is connected to the hydraulic circuit, and an on-off valve is arranged in a branch path that is branched and connected to the hydraulic circuit. A control valve for controlling the opening / closing of the opening / closing valve based on the output signal of the switch and the output signal of the pressure sensor, and opening the opening / closing valve when the hydraulic cylinder is stopped to open the hydraulic pump in a light load state. In this configuration, the motor for rotating the hydraulic pump is rotated in a light load state so that the fan provided in the motor cools the motor itself. A hydraulic circuit control device for an industrial vehicle for cargo handling, comprising: 4. The cargo handling industrial vehicle according to claim 3, wherein the on-off valve control unit includes an operation confirmation unit that determines whether or not the operation lever is operated when the pressure sensor is activated. Hydraulic circuit controller.