JPH072500A - Hydraulic control device - Google Patents

Abstract

PURPOSE:To make a turn direction of a stepping motor coping with an operating direction of an operating means even when the stepping motor steps out. CONSTITUTION:In a controller 3, an operating position of a cargo handling lever 1 is detected from output voltage of a potentiometer 2. In the controller 3, a stepping motor 10 is detected for whether it is placed in a neutral position or not from an on-off condition of a limit switch 20 provided in the stepping motor 10. In the case of not placing the cargo handling lever 1 but placing the stepping motor 10 in the neutral position, supply of power for driving the stepping motor 10 is stopped, in the controller 3. Thereafter, when detecting the stepping motor 10 and the cargo handling lever 1 placed in the neutal position, the driving power is again supplied to the stepping motor 10, in the controller 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device, and more particularly to a hydraulic control device having a stepping motor for driving and controlling a spool of a cargo control valve.

[0002]

2. Description of the Related Art Conventionally, a control valve is provided in a forklift of an industrial vehicle. By adjusting the spool movement amount and its direction of the control valve, the supply amount and the supply direction of the hydraulic oil supplied to the hydraulic cylinder are determined. Further, in recent years, a hydraulic control device has been proposed which controls a spool of a control valve by a stepping motor. This hydraulic control device is shown in FIG.

The cargo handling lever 51 is provided with a potentiometer 52 for detecting the operation amount thereof. The potentiometer 52 detects the operation amount of the cargo handling lever 51 and outputs it to the controller 53. The controller 53 drives and controls the stepping motor 54 based on the operation amount of the cargo handling lever 51, moves the spool 56 of the control valve 55, and stops the spool 56 at a target position corresponding to the operation amount of the cargo handling lever 51.

Hydraulic oil is supplied to a hydraulic cylinder (not shown) in accordance with the position of the spool 56, so that the fork moves up and down. The stepping motor 54 is controlled by a drive voltage (constant voltage) supplied from a battery (not shown).

[0005]

By the way, at the point A in FIG. 4 in the middle of raising the fork by operating the cargo handling lever 51 in the ascending direction, a load larger than the torque generated in the stepping motor 54 for some reason is applied. The stepping motor 54 may be added. At this time, the rotor of the stepping motor 54 is displaced from the position where it should be,
The torque generated in the stepping motor 54 disappears and the step is lost. When the stepping motor 54 loses step, the spool 56 returns to the neutral position due to the force of a spring (not shown) provided in the control valve 55.

After that, when the cargo handling lever 51 is returned to the neutral direction, the controller 53 controls the stepping motor 54 to rotate according to the operation amount of the cargo handling lever 51. This time,
Since the stepping motor 54 is already in the neutral position,
Although the cargo handling lever 51 is in the neutral position, the stepping motor 54 rotates in the descending direction from the neutral position. As a result, the fork is lowered unlike the operation of the cargo handling lever 51. Therefore, there is a problem that the hydraulic cylinder cannot be operated corresponding to the operation of the cargo handling lever 51, and the cargo handling work cannot be performed.

An object of the present invention is to provide a hydraulic control device capable of making the operating direction of the operating means correspond to the rotating direction of the stepping motor even when the stepping motor is out of step.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to an operating means operated to drive a hydraulic system, an operating amount detecting means for detecting an operating amount of the operating means, The spool includes a control valve whose spool is held in a neutral position by an elastic member, and a stepping motor which operates the spool of the control valve against the elastic force of the elastic member. In a hydraulic control device for dynamically controlling a spool of a control valve to control hydraulic oil supplied to the hydraulic device via the control valve, an operating range of the operating means is determined based on a detection result of the operation amount detecting means. The operation position determination means for determining whether the spool is in the operation range for setting the neutral position and the rotation position of the stepping motor are set. The rotational position detecting means for outputting, and the rotational position for determining whether or not the rotational position of the stepping motor is at the rotational position for setting the spool to the neutral position based on the detection result of the rotational position detecting means. Determination means, and a control means for determining whether or not the stepping motor is out of step based on the determination results of the both determination means, and when it is determined that the stepping motor is out of step, controlling the stepping motor to a state in which it can be returned to the neutral position. The main point is to provide.

[0009]

According to the present invention thus constructed, the operating position judging means detects that the operating amount of the operating means for driving the hydraulic device is detected by the operating quantity detecting means. It is determined whether or not it is within the operation range for moving to the position. The rotational position detecting means detects the rotational position of the stepping motor. The rotation position determination means determines whether or not the rotation position of the stepping motor is at the rotation position for setting the spool to the neutral position based on the detection result of the rotation position detection means. Then, the control means determines whether or not the stepping motor is out of step based on the determination results of both determination means, and when it is determined that the stepping motor is out of step, the control means controls the stepping motor to a state in which it can be returned to the neutral position.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. As shown in FIG. 1, the cargo handling lever 1 is provided in a driver's seat of a forklift (not shown). The cargo handling lever 1 is connected to a potentiometer 2 that detects the operation amount (angle) thereof. The potentiometer 2 is connected to the controller 3.

The forklift is also provided with a hydraulic cylinder 4 for moving the fork up and down. Hydraulic cylinder 4
Is connected to the control valve 5. Hydraulic oil is supplied to the control valve 5 by a hydraulic pump 7 which is rotationally driven by a cargo handling pump motor 6. Further, a spool 8 is slidably provided in the control valve 5, and a pair of springs (shown by broken lines) 9 for constantly pressing and holding the spool 8 at a neutral position.
Is provided. By sliding the control valve 3 up and down against the pressure of the spring 9 of the spool 8, the hydraulic oil supplied from the hydraulic pump 7 is supplied to the hydraulic cylinder 4 so that the fork moves up and down. ing.

That is, hydraulic oil is supplied to the hydraulic cylinder 4 in an amount corresponding to the moving position of the spool 8. When the spool 8 is in the neutral position, hydraulic oil is not supplied to the hydraulic cylinder 4, and the position of the fork is maintained. Further, the hydraulic cylinder 4 is supplied with an amount of hydraulic oil corresponding to the moving position of the spool 8, and the fork moves up and down at a speed corresponding to the amount.

A stepping motor 10 is connected to the spool 8 via a link mechanism 11. Then, the rotational movement of the stepping motor 10 is converted into a linear movement by the link mechanism 11, and the movement of the spool 8 is controlled.

The link mechanism 11 comprises a connecting link 12, a first link 13, a second link 14, a fixed shaft 15 and a third link 16. One end of a connecting link 12 is rotatably attached to the spool 8. The other end of the connecting link 12 is rotatably attached to the center of the first link 13. One end of the first link 13 is rotatably attached to one end of the second link 14 and the other end is rotatably attached to a fixed shaft 15. The other end of the second link 14 is rotatably attached to one end of the third link 16. The other end of the third link 16 is formed into a substantially disc shape. An arm portion 17 is formed on one of the outer circumferences of the third link 16 so as to project in the radial direction, and a recess portion 18 is formed on the other. The tip of the arm 17 is connected to the second link 14. The third link 16 has the output shaft 19 of the stepping motor 10 at its center.
Is pivotally attached so that it cannot rotate.

A limit switch 20 is provided in the recess 18. The limit switch 20 is turned off (open circuit) when the cargo handling lever 1 is in the neutral position, that is, when the spool 8 is in the neutral position. Then, the limit switch 20 is turned on (closed) by the recess 18 of the third link 16 when the stepping motor 10 rotates. In the present embodiment, as shown in FIG. 3, the limit switch 20 is turned on when the stepping motor 10 is in a position (rotational position) rotated by 10 degrees from the neutral position. At this time, the spool 7 is in the neutral position and the hydraulic oil is supplied to the control valve 5.
It doesn't flow from.

The limit switch 20 is connected to the controller 3. Controller 3 is limit switch 2
0 on or off state is detected. When the controller 3 detects the off state of the limit switch 20, the controller 3 determines that the stepping motor 10 is in the neutral position. When the controller 3 detects the ON state of the limit switch 20, the controller 3 determines that the stepping motor 10 is not in the neutral position.

Next, the electrical configuration of the hydraulic control device will be described. A potentiometer 2 provided on the cargo handling lever 1 is connected to the controller 3. The controller 3 inputs an operation angle at a predetermined voltage as an operation amount of the cargo handling lever 1 detected by the potentiometer 2. In this embodiment, when the cargo handling lever 1 is in the neutral position,
The controller 3 outputs the potentiometer 2 with an output voltage of 2.5.
Enter V. Further, when the cargo handling lever 1 is in the position tilted to the rising side (raising operation position), the controller 3 inputs the value of the output voltage 3V to 4.5V of the potentiometer 2. Then, when the cargo handling lever 1 is in the position tilted to the lower side (lowering operation position), the controller 3 inputs the output voltage 0.5V to 2V of the potentiometer 2. Therefore,
The controller 3 inputs the operating position of the cargo handling lever 1 based on the output voltage of the potentiometer 2. Therefore, the controller 3 can detect the operating position of the cargo handling lever 1 from the output voltage of the potentiometer 2.

A stepping motor 10 is connected to the controller 3. The controller 3 controls ON / OFF of the drive voltage supplied to the stepping motor 10. Further, the controller 3 outputs a drive (pulse) signal corresponding to a predetermined drive frequency to the stepping motor 10 in correspondence with the forward or reverse rotation direction. The stepping motor 10 is the controller 3
When the driving power is supplied from the device and the driving signal is output, the motor rotates according to the driving signal. Further, the stepping motor 10 is configured to be pressed and held at the neutral position by the pressing force of the spring 9 in the control valve 5 when the driving power is not supplied from the controller 3.

As shown in FIG. 2, the controller 3 stores an operation amount-rotational position map for controlling the stepping motor 10. The controller 3 calculates the voltage output from the potentiometer 2 as the operation amount of the cargo handling lever 1 according to the operation amount-rotation amount map.
The rotation position of the stepping motor 10 is read out as the position. Then, the controller 3 drives and controls the stepping motor 10 up to the position corresponding to this rotating position.

In this manipulated variable-rotational position map, when the output voltage of the potentiometer 2 is a value between 2.9 V and 3.1 V, that is, when the voltage is near the neutral position of the cargo handling lever 1, the controller 3 steps. The drive of the motor 10 is not controlled. That is, 2.9V to 3.1V
During this period, there is a dead zone of the cargo handling lever 1, and the stepping motor 10 does not rotate when the cargo handling lever 1 moves only slightly from the neutral position.

When the operation amount of the cargo handling lever 1 passes the dead zone, the rotational position of the stepping motor 10 increases in accordance with the operation amount. Further, in a region where the operation amount of the cargo handling lever 1 is large, the stepping motor 10 is rotated to the maximum rotation position to slide the spool 8.

In this embodiment, when the operation amount of the cargo handling lever 1 is 3.25V, the stepping motor 10 is drive-controlled to a rotation position of 10 degrees in the upward direction from the neutral position, and when it is 4V, the stepping motor 10 is driven. Is driven and controlled from the neutral position to a rotation position of 60 degrees. When the operation amount of the cargo handling lever 1 is 2.75V, the stepping motor 1
0 is driven and controlled from the neutral position to a rotation position of -10 degrees,
When it is 1V, the stepping motor 10 moves from the neutral position to −
The drive is controlled to a rotation position of 60 degrees.

Further, a limit switch 20 provided on the stepping motor 10 is connected to the controller 3. The controller 3 inputs the ON / OFF state of the limit switch 20 as the rotational position of the stepping motor 10 detected by the limit switch 20. Figure 3
As shown in, when the stepping motor 10 is in the neutral position, the controller 3 inputs that the limit switch 20 is in the off state. When the stepping motor 10 rotates upward or downward by 10 degrees or more, the controller 3 inputs that the limit switch 20 is in the ON state. Therefore, the controller 3 controls the stepping motor 10 depending on the state of the limit switch 20.
It is possible to input whether is in the neutral position or in the rotating position in the ascending or descending direction.

Further, the controller 3 controls the input voltage from the potentiometer 2 and the ON / OFF of the limit switch 20.
The operating position of the cargo handling lever 1 and the rotating position of the stepping motor 10 are compared based on the off state. Then, the output voltage of the potentiometer 2 is 3.25.
Between V and 4.5 V, that is, when the cargo handling lever 1 is in the raising operation position and the limit switch 20 is in the ON state, the controller 3 determines that the stepping motor 10 is not out of step. Also, the output voltage of potentiometer 2 is 0.5V.
Between 1.75V, that is, when the cargo handling lever 1 is in the lowering operation position and the limit switch 20 is in the ON state, the controller 3 determines that the stepping motor 10 is not out of step.

On the other hand, when the output voltage of the potentiometer 2 is between 0.5 V and 1.75 V or between 3.25 V and 4.5 V, that is, when the cargo handling lever 1 is in the raising operation position or the lowering operation position, the limit switch 20 operates. In the off state, the controller 3 determines that the stepping motor 10 is out of step. At this time, the controller 3 stops the drive voltage supplied to the stepping motor 10 and resets the rotation position of the stepping motor 10.

The output voltage of the potentiometer 2 is 1.
Between 75V and 3.25V, that is, when the cargo handling lever 1 is in the neutral position and the limit switch 20 is in the ON state, the controller 3 determines that the stepping motor 10 is out of step. At this time, the controller 3 stops the drive voltage supplied to the stepping motor 10 and resets the rotation position of the stepping motor 10.

Next, the controller 3 monitors the output voltage of the potentiometer 2. And potentiometer 2
Output voltage is 2.5 V, that is, when the cargo handling lever 1 is in the neutral position, the drive voltage is supplied to the stepping motor 10 again. Then, the controller 3 controls the rotation of the stepping motor 10 based on the amount of subsequent operation of the cargo handling lever 1.

Next, the operation of the hydraulic control device thus constructed will be described. The worker turns on the power of the controller 3 in order to perform the cargo handling work. Then, the controller 3 supplies drive power to the stepping motor 10.

Next, the operator tilts the cargo handling lever 1 to the ascending side in order to raise the fork. Controller 3
Reads the rotation position of the stepping motor 10 from the input voltage from the potentiometer 2, that is, the stored operation amount-rotation position map based on the operation amount of the cargo handling lever 1.
Then, the controller 3 outputs a drive signal to the stepping motor 10 to drive and control the stepping motor 10 to the rotating position.

Then, the controller 3 reads the state of the limit switch 20. When the cargo handling lever 1 is not in the neutral position and the limit switch 20 is in the on state, the controller 3 determines that the stepping motor 10 is not out of step. Then, the controller 3 continues to control the stepping motor 10 based on the operation amount of the cargo handling lever 1. At this time, since the stepping motor 10 is in the neutral position, hydraulic oil is not supplied from the control valve 5 to the hydraulic cylinder 4.

On the other hand, the cargo handling lever 1 is not in the neutral position,
When the limit switch 20 is off, the controller 3 determines that the stepping motor 10 is out of step. Then, the controller 3 stops the drive power supply supplied to the stepping motor 10. As a result, the stepping motor 10 does not rotate even if a drive signal is supplied from the controller 3 based on the operation amount of the cargo handling lever 1.

When the operator returns the cargo handling lever 1 to the neutral position, the controller 3 reads the output voltage of the potentiometer 2 and detects that the cargo handling lever 1 is at the neutral position. Then, the controller 3 supplies drive power to the stepping motor 10 again. After that, when the cargo handling lever 1 is cargo-operated, the controller 3 rotates the stepping motor 10 based on the operation amount. Therefore, the operating direction of the cargo handling lever 1 and the rotating direction of the stepping motor 10 coincide with each other.

When the cargo handling lever 1 is in the neutral position and the limit switch 20 is in the ON state, the controller 3 determines that the stepping motor 10 is out of step. Then, the controller 3 stops the drive power supply supplied to the stepping motor 10. As a result, the stepping motor 10 is moved to the neutral position by the pressing force of the spring 9 in the control valve 5, and the limit switch 20 is turned off. Then, the cargo handling lever 1 is in the neutral position, and the controller 3 operates the limit switch 20.
When the off state is detected, the controller 3 supplies drive power to the stepping motor 20 again. After that, when the cargo handling lever 1 is cargo-operated, the controller 3 rotates the stepping motor 10 based on the operation amount. Therefore, the operating direction of the cargo handling lever 1 and the stepping motor 1
The rotation directions of 0 are the same.

As described above, in the hydraulic control system according to the present embodiment, when the cargo handling lever 1 is in the raising or lowering operation position and the stepping motor 10 is in the neutral position, the controller 3 supplies the driving power supply to the stepping motor 10. Stop. Then, when the cargo handling lever 1 returns to the neutral position,
Since the controller 3 supplies the driving power again to the stepping motor 10,
Even when step out occurs, the operating direction of the cargo handling lever 1 and the rotating direction of the stepping motor 10 can be matched.

The present invention is not limited to the above embodiments, but may be modified as follows without departing from the spirit of the present invention. (1) In the above embodiment, the hydraulic cylinder 4 is used for raising and lowering the fork, but it may be applied to other hydraulic cylinders for reach and tilt. Further, it may be applied to a cargo handling vehicle other than a forklift.

(2) Although the limit switch 20 is used to detect the neutral position of the stepping motor 10 in the above embodiment, the stepping motor 10 is provided with a rotary encoder or the like to detect the neutral position of the stepping motor 10. May be.

(3) In the above embodiment, the stepping motor 10 is provided with the limit switch 20 to detect the neutral position of the stepping motor 10. May be detected.
Further, a spool sensor may be provided on the spool 8 and the neutral position of the stepping motor 10 may be detected based on the output thereof.

[0038]

As described above in detail, according to the hydraulic control apparatus of the present invention, when it is determined that the stepping motor is out of step, the stepping motor is controlled to be in a state where it can be returned to the neutral position. Therefore, even when the stepping motor is out of step, there is an excellent effect that the operating direction of the operating means and the rotating direction of the stepping motor can be matched.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hydraulic control device showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an output voltage of a potentiometer of a cargo handling lever and a rotation amount of a stepping motor.

FIG. 3 is a characteristic diagram showing a turning position of a stepping motor and ON / OFF states of limit switches.

FIG. 4 is a characteristic diagram showing a relationship between an operation amount of a lever and a rotation amount of a stepping motor.

FIG. 5 is a schematic configuration diagram showing a conventional hydraulic control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cargo handling lever as operation means, 2 ... Potentiometer as operation amount detection means, 3 ... Operation position determination means, rotation position determination means, and controller as control means, 4
... hydraulic cylinder as a hydraulic device, 5 ... control valve, 8 ... spool, 9 ... spring as elastic member, 10 ... stepping motor, 20 ... limit switch as rotational position detecting means

Front page continuation (72) Inventor Yasuhiko Naruse 2-chome, Toyota-cho, Kariya city, Aichi Prefecture Toyota Industries Corp.

Claims (1)

[Claims] 1. An operating device operated to drive a hydraulic system, an operating amount detecting device for detecting an operating amount of the operating device, and a control valve in which a spool is held at a neutral position by an elastic member. A stepping motor that operates the spool of the control valve against the elastic force of the elastic member, and controls the spool of the control valve by controlling the rotation of the stepping motor according to the operation amount of the operating means. In a hydraulic control device for controlling the hydraulic oil supplied to the hydraulic device via the operation device, it is determined whether the operating range of the operating means is within the operating range for setting the spool to the neutral position based on the detection result of the operating amount detecting means. Operating position determining means for determining, rotating position detecting means for detecting a rotating position of the stepping motor, and rotating position detecting means Rotation position determining means for determining whether or not the rotation position of the stepping motor is at the rotation position for setting the spool to the neutral position based on the detection result of stepping motor; A hydraulic control device comprising: a control unit that determines whether or not the motor is out of step and, if it is determined that the step is out of step, controls the stepping motor to a state in which it can return to the neutral position.