JP4250726B2 - Power steering device and industrial vehicle having power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power steering device such as a forklift and an industrial vehicle having the power steering device.
[0002]
[Prior art]
Conventionally, a power steering mechanism that detects a steering amount of a steering wheel by a sensor and controls a hydraulic mechanism according to the detected steering amount is known.
USP, 542,490 (Patent Document 1) describes that the hydraulic pressure of the cargo handling and steering is controlled by one motor and hydraulic oil is supplied with priority over the hydraulic mechanism for steering. In the invention of Patent Document 1, rotation of a steering wheel is detected by an optical sensor.
[0003]
We previously proposed a power steering device that detects the angle of the steered wheels with a tire angle sensor and supplies hydraulic oil to the hydraulic mechanism for power steering based on the angular velocity of the wheels.
[0004]
[Patent Document 1]
USP 5,542,490 (Figure 1, ABSTRACT, page 2)
[0005]
[Problems to be solved by the invention]
By the way, when controlling the hydraulic motor that supplies the working oil to the hydraulic mechanism, when the direction lever is not set to the traveling state, the hydraulic motor is stopped and the direction lever is switched to the traveling position. Sometimes, it is conceivable to rotate the hydraulic motor at a low speed.
[0006]
FIG. 8 is a diagram showing a change in the number of rotations of the hydraulic motor at the start. In a battery forklift or the like, the hydraulic motor is started at a low rotational speed in order to reduce power consumption by the hydraulic motor. In this case, the rotational speed of the hydraulic motor rises from 0 with a constant slope to a constant idle rotational speed.
[0007]
However, when such motor control is performed, the rise of the rotation of the hydraulic motor is delayed, so that if the steering operation is performed immediately after the direction lever is switched to the travel position, the hydraulic mechanism of the power steering device operates sufficiently. Since the oil is not supplied, the steering operation is caught.
[0008]
An object of the present invention is to enable a steering operation to be smoothly performed from the start of a hydraulic motor.
[0009]
[Means for Solving the Problems]
The present invention provides a power steering apparatus having a hydraulic mechanism for transmitting an operation of a steering wheel to a steered wheel, a hydraulic pump for supplying hydraulic oil to the hydraulic mechanism, and driving the hydraulic pump to supply hydraulic oil to the hydraulic mechanism. The hydraulic motor to be supplied and when the direction lever is switched to the travel position in a state where the hydraulic motor is stopped, the rotational speed of the hydraulic motor is set high at the time of start-up, and the hydraulic oil to the hydraulic mechanism And a motor control circuit for controlling the rotational speed of the hydraulic motor to a rotational speed corresponding to a steering operation after a certain time.
[0010]
According to this invention, since the hydraulic oil can be sufficiently supplied to the hydraulic mechanism from the start of the hydraulic motor, even when the steering operation is performed immediately after the operation for starting the vehicle is performed, Power steering can be activated. As a result, for example, even when the direction lever for instructing the traveling direction is switched from the neutral position to the traveling position while the hydraulic motor is stopped, the steering can be reduced and the steering operation can be performed smoothly. .
[0011]
Another power steering device of the present invention includes a sensor that detects a wheel angle of a steered wheel, a hydraulic mechanism that transmits an operation of the steering wheel to the steered wheel, a hydraulic pump that supplies hydraulic oil to the hydraulic mechanism, A hydraulic motor that drives a hydraulic pump to supply hydraulic oil to the hydraulic mechanism, and the steering that is detected when the direction lever is switched to a traveling position with the hydraulic motor stopped or detected by the sensor When the angular velocity obtained from the wheel angle is larger than 0, the rotational speed of the hydraulic motor is set to be high at start-up to increase the amount of hydraulic oil supplied to the hydraulic mechanism. When the angular velocity is 0, the rotational speed of the hydraulic motor is set to a lower rotational speed than when starting, and when the angular speed of the steered wheels is greater than 0, the angular speed of the steered wheels is set. Controlling the rotational speed of the hydraulic motor to the rotation speed corresponding to and a motor control circuit.
[0012]
According to the present invention, when the direction lever is switched to the traveling position from the state where the hydraulic motor is stopped, or when the angular speed of the steering wheel is greater than 0, the rotational speed of the hydraulic motor is set high. The hydraulic oil can be sufficiently supplied to the hydraulic mechanism, and the power steering can be operated from the start.
[0013]
An industrial vehicle having a power steering device according to the present invention is a power steering device for an industrial vehicle that supplies hydraulic oil from one hydraulic pump to both a cargo handling hydraulic mechanism and a power steering hydraulic mechanism. A sensor that detects the angle of the wheel, a hydraulic mechanism that transmits the operation of the steering wheel to the steering wheel, a hydraulic pump that supplies hydraulic oil to the hydraulic mechanism, and a hydraulic pump that drives the hydraulic pump to supply hydraulic oil to the hydraulic mechanism When the direction lever is switched to the travel position with the hydraulic motor to be supplied and the hydraulic motor stopped, or when the angular velocity obtained from the angle of the steering wheel detected by the sensor is greater than 0, At the time of start-up, the rotational speed of the hydraulic motor is set high to increase the amount of hydraulic oil supplied to the hydraulic mechanism. When the angular speed of the steering wheel is 0, the rotational speed of the hydraulic motor is set to a lower rotational speed than when starting, and when the angular speed of the steering wheel is greater than 0, the rotational speed is set to the rotational speed according to the angular speed of the steering wheel. A motor control circuit for controlling the rotation speed of the hydraulic motor.
[0014]
According to the present invention, when the direction lever is switched to the traveling position from the state where the hydraulic motor is stopped, or when the angular speed of the steering wheel is greater than 0, the rotational speed of the hydraulic motor is set high. The hydraulic oil can be sufficiently supplied to the hydraulic mechanism, and the power steering can be operated from the start.
[0015]
Another industrial vehicle having the power steering device of the present invention includes a cargo handling hydraulic mechanism for carrying out a cargo handling operation, a power steering hydraulic mechanism for transmitting an operation of a steering wheel to a steered wheel, the cargo handling hydraulic mechanism, A hydraulic pump that supplies hydraulic oil to a power steering hydraulic mechanism; a hydraulic motor that drives the hydraulic pump to supply hydraulic oil to the cargo handling hydraulic mechanism and the power steering hydraulic mechanism; When the direction lever is switched to the traveling position with the sensor for detecting the angle and the hydraulic motor stopped, or when the angular velocity obtained from the angle of the steered wheel detected by the sensor is greater than 0, At the time of start-up, the rotational speed of the hydraulic motor is set high to increase the amount of hydraulic oil supplied to the hydraulic mechanism. Soon after, when the angular speed of the steering wheel is zero, the rotational speed of the hydraulic motor is set to a lower rotational speed than at the start, and when the angular speed of the steering wheel is larger than zero, the angular speed of the steering wheel is set. A motor control circuit for controlling the number of rotations of the hydraulic motor.
[0016]
According to the present invention, since the hydraulic oil can be sufficiently supplied to the hydraulic mechanism by setting the rotation speed at the start of the hydraulic motor high, the power steering can be sufficiently operated immediately after the start. Further, the power consumption for driving the hydraulic motor can be reduced by setting the number of rotations of the hydraulic motor to be equal to or less than that at the start in accordance with the angular velocity of the steered wheels after a certain time.
[0017]
For example, the hydraulic mechanism of claim 1 corresponds to the power steering valve 24 and the power steering cylinder 26 of FIG. 2, and the steering wheel corresponds to the tire 14 of FIG. The hydraulic motor corresponds to the hydraulic motor 22 in FIG. 2, and the motor control circuit corresponds to the control unit 28 in FIG.
[0018]
The sensor of claim 2 corresponds to the tire angle sensor 27 of FIG. 2, the hydraulic mechanism corresponds to the power steering valve 24 and the power steering cylinder 26 of FIG. 2, and the hydraulic pump is the hydraulic pump 21 of FIG. The hydraulic motor corresponds to the hydraulic motor 22 in FIG. 2, the direction corresponds to the direction lever 18 in FIG. 1, and the motor control circuit corresponds to the control unit 28 in FIG.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are an external top view and a side view of a battery forklift 11 according to the embodiment.
[0020]
The battery forklift 11 has a three-wheel configuration having a pair of left and right drive wheels 12 and 13 at the front part of the vehicle body and a steering wheel 14 at the rear part. The left and right drive wheels 12, 13 are respectively driven by a left wheel drive motor and a right wheel drive motor (not shown). The tire 14 that is a steered wheel is provided at a position that passes through the central portion of the shaft that connects the left drive wheel 12 and the right drive wheel 13.
[0021]
A mast device 15 for carrying a load is provided in front of the left and right drive wheels 12 and 13, and a driver's seat is provided between the left and right drive wheels 12 and 13 and the tire 14. The driver's seat is provided with a steering wheel 16, a cargo handling lever 17 that is operated when the mast device 15 is moved up and down, a direction lever 18 that instructs a traveling direction, an accelerator pedal, a brake pedal, and the like. The direction lever 18 can be switched between three positions: forward, neutral, and reverse.
[0022]
FIG. 2 is a diagram illustrating a configuration of a main part related to the power steering device of the battery forklift 11, and FIG. 3 is a diagram illustrating a configuration of the control unit 28 of FIG.
The hydraulic pump 21 supplies hydraulic oil to the hydraulic mechanism of the power steering device and the hydraulic mechanism of the mast device 15 that performs cargo handling, and is driven by a hydraulic motor 22. The hydraulic motor 22 controls the operation of the hydraulic pump 21 to control the amount of hydraulic oil supplied from the hydraulic pump 21 to the hydraulic mechanism.
[0023]
The priority valve 23 is a valve that supplies hydraulic oil with priority over one hydraulic mechanism (in the embodiment, the hydraulic mechanism of the power steering device), and prioritizes hydraulic oil required by the power steering (PS) valve 24. The remaining hydraulic oil is supplied to the cargo handling cylinder 25.
[0024]
The power steering valve 24 supplies hydraulic oil corresponding to the left and right steering speed of the steering wheel 16 to the power steering cylinder 26.
The power steering cylinder 26 is operated by hydraulic oil supplied with the steering direction being distinguished from the power steering valve 24, and rotates the tire 14 in the right direction or the left direction.
[0025]
The tire angle sensor 27 is configured by a potentiometer or the like provided on the rotation axis of the tire 14, detects the rotation angle of the tire 14, and outputs the detected rotation angle to the control unit 28.
As shown in FIG. 3, the control unit 28 includes a CPU 31, a RAM 32, a ROM 33 storing a motor control program and the like, and an input / output unit (I / O) 34. A control signal a indicating the angle of the tire 14, an operation signal b for the direction lever 18, an operation signal for the cargo handling lever 17, and the like are input from the tire angle sensor 27 to the input / output unit 34 of the control unit 28. Further, the CPU 31 of the control unit 28 obtains an angular velocity from the angle of the tire 14 detected by the tire angle sensor 27, and sends a control signal c for controlling the rotation speed according to the angular velocity via the input / output unit 34. Output to.
[0026]
Next, FIG. 4 is a control flowchart of the power steering apparatus according to the first embodiment of the present invention. In the first embodiment, when the direction lever 18 is switched from the neutral position to the traveling position, the rotational speed at the start of the hydraulic motor 22 is set high.
[0027]
The control unit 28 determines whether the hydraulic motor 22 is in a stopped state or a state immediately after being started from the stopped state (FIG. 4, S11).
When the hydraulic motor 22 is in a stopped state or just after starting (S11, YES), whether or not the direction lever 18 is turned on based on the control signal b output from the direction lever 18, that is, the direction lever 18 is moved from the neutral position. It is determined whether or not the traveling position (forward or reverse position) has been switched (FIG. 4, S12).
[0028]
When the direction lever 18 is switched to the travel position (S12, YES), it is next determined whether or not a certain time has elapsed since the hydraulic motor 22 was activated (FIG. 4, S13).
If the predetermined time has not elapsed (S13, NO), the hydraulic motor 22 is rotated at a high rotational speed (FIG. 4, S14).
[0029]
By the process of step S14, a large amount of hydraulic oil is supplied from the hydraulic pump 21 to the priority valve 23 at the start, and as a result, a large amount of hydraulic oil is supplied to the power steering valve 24. Power steering can be activated in a short time.
[0030]
On the other hand, when the hydraulic motor 22 is not stopped and not immediately after starting (S11, NO), when the hydraulic motor 22 is stopped or immediately after starting and the direction lever 18 is not switched (S12, NO), or when it is determined that the directional lever 18 has been switched to the travel position immediately after the hydraulic motor 22 is stopped or started and a predetermined time has elapsed since the hydraulic motor 22 was started (S13, YES), step Proceeding to S15, motor rotation processing corresponding to the angular velocity of the tire 14 is executed.
[0031]
In the process of step S15, for example, when the hydraulic motor 22 is just started and the direction lever 18 is switched to the travel position, and a certain time has elapsed from the start and the angular velocity of the tire 14 is 0, the idle rotation is lower than that at the start. The hydraulic motor 22 is rotated by switching to the number. Alternatively, when the tire angular velocity is greater than 0, the rotation of the hydraulic motor 22 is controlled at the number of rotations corresponding to the angular velocity of the tire 14.
[0032]
FIG. 5 is a diagram showing a change in the number of rotations since the hydraulic motor 22 is started.
When the direction lever 18 is switched to the travel position in a state where the hydraulic motor 22 is stopped, the control unit 28 causes the hydraulic motor 22 to rotate at a higher speed than the idle rotational speed (a low rotational speed when the steering operation is not performed). A control signal c for rotating by a number is output. As a result, the hydraulic motor 22 rotates at a higher rotational speed than the idle rotational speed.
[0033]
When the tire angular velocity is 0 after a certain time has elapsed since the start, the control unit 28 outputs a control signal c that causes the hydraulic motor 22 to rotate at an idle speed lower than that at the start. As a result, the hydraulic motor 22 rotates at a lower idle speed than at the start. According to the first embodiment described above, in the power steering device that supplies hydraulic oil to the power steering valve 24 in accordance with the angular velocity of the tire 14, when the hydraulic motor 22 is started from the stop state, the idle rotational speed is determined. Rotate at high speed. Thereby, the rise of the rotation speed of the hydraulic motor 22 can be accelerated, and the power steering can be operated in a short time. Therefore, even when the steering operation is performed immediately after the direction lever 18 is switched to the traveling position, the steering operation can be performed smoothly, and the catching of the steering can be reduced.
[0034]
In addition, when the steering operation is not performed after a certain period of time after the direction lever 18 is switched and the tire angular velocity is 0, the idle rotational speed is set to be lower than that at the start, so the hydraulic motor 22 continues to rotate. Power consumption can be reduced.
[0035]
Next, FIG. 6 is a control flowchart of the power steering apparatus according to the second embodiment of the present invention. In the second embodiment, when the direction lever 18 is switched to the traveling position, or when the tire angular velocity is not 0, the hydraulic motor 22 is started at a high rotational speed.
[0036]
The control unit 28 determines whether or not the hydraulic motor 22 is stopped or just after starting (FIG. 6, S21).
When the hydraulic motor 22 is stopped or immediately after starting (S21, YES), whether the direction lever 18 is turned on, that is, whether the direction lever 18 is switched from the neutral position to the traveling position, or It is determined whether or not the tire angular velocity is greater than 0 (FIG. 6, S22).
[0037]
When the direction lever 18 is switched to the travel position or when the tire angular velocity is greater than 0 (S22, YES), it is determined whether or not a certain time has elapsed since the hydraulic motor 22 was started (FIG. 6,). S23).
When the predetermined time has not elapsed (S23, NO), high motor rotation processing is executed, and the hydraulic motor 22 is rotated at a higher rotational speed than the idle rotational speed (FIG. 6, S24).
[0038]
When the hydraulic motor 22 is not stopped and not immediately after startup (S21, NO), the hydraulic motor 22 is stopped or immediately after startup, the direction lever 18 is not switched to the travel position, and the tire angular velocity Is determined to be 0 (S22, NO), or when the hydraulic motor 22 is stopped or immediately after starting, the direction lever 18 is switched to the running position, or the tire angular velocity is 0 and the hydraulic motor 22 is started. When it is determined that a certain time has elapsed since the start (S23, YES), the process proceeds to step S25, and an appropriate rotation process according to the tire angular speed is executed.
[0039]
In the process of step S25, for example, after the hydraulic motor 22 is stopped, the direction lever 18 is switched from the neutral position to the traveling position, or the tire angular speed is greater than 0 and started at a rotational speed higher than the idle rotational speed. When the tire angular velocity is zero after a predetermined time has elapsed, the rotation of the hydraulic motor 22 is controlled so that the idle rotation speed is lower than the rotation speed at the start. In addition, when the hydraulic motor 22 is not immediately after starting and the tire angular velocity is not 0, the rotation of the hydraulic motor 22 is controlled so that the rotational speed corresponds to the tire angular velocity.
[0040]
According to the second embodiment, when the steering motor is operated immediately after setting the direction lever 18 to the traveling position with the hydraulic motor 22 stopped, or without switching the direction lever 18, the steering When the operation is performed to change the angle of the tire 14 of the steered wheel, the hydraulic motor 22 is rotated at a higher rotational speed than the idle rotational speed at the time of starting. As a result, it is possible to sufficiently supply hydraulic oil to the hydraulic mechanism for power steering so that the power steering works immediately after starting. Therefore, the steering operation can be reduced. In addition, when the steering operation is not performed after a certain time and the tire angular velocity is 0, the hydraulic motor 22 is rotated at an idle rotational speed lower than that at the time of starting, so that the power consumption by continuing to rotate the hydraulic motor 22 Can be reduced.
[0041]
Next, FIG. 7 is a diagram showing a configuration of a main part related to the power steering apparatus according to the third embodiment of the present invention.
The difference between the third embodiment and the second embodiment shown in FIG. 2 is that hydraulic oil is supplied only from the hydraulic pump 21 to the power steering valve 24. In this case, since it is not necessary to supply hydraulic oil from the hydraulic pump 21 to both the cargo handling cylinder 25 and the power steering valve 24, the priority valve 23 becomes unnecessary.
[0042]
Also in the third embodiment, as in the first and second embodiments described above, when the hydraulic motor 22 is stopped and the direction lever 18 is set to the travel position, the hydraulic motor By rotating the motor 22 at a rotational speed higher than the idle rotational speed, even when the steering operation is performed immediately after the direction lever 18 is switched to the traveling position, the occurrence of the steering operation can be reduced.
[0043]
The present invention is not limited to the above-described embodiment, and may be configured as follows.
(A) In the above-described embodiment, the rotational speed of the hydraulic motor 22 is controlled based on the angular velocity of the tire angle sensor. In the power steering device that detects the operation amount of the steering wheel by the sensor, the hydraulic motor The present invention can also be applied to a case where the hydraulic motor 22 is activated when a steering operation is detected while the vehicle is in a stopped state.
(B) The present invention is applicable not only to forklifts but also to other industrial vehicles. The invention is not limited to a three-wheel forklift.
[0044]
【The invention's effect】
According to the present invention, the steering motor can be smoothly operated from the start of the hydraulic motor by rotating the hydraulic motor at a high rotational speed at the start and sufficiently supplying hydraulic oil to the hydraulic mechanism for the power steering. Can be.
[Brief description of the drawings]
FIGS. 1A and 1B are an external top view and a side view of a forklift.
FIG. 2 is a diagram showing a configuration of a main part related to a power steering device.
FIG. 3 is a diagram illustrating a configuration of a control unit.
FIG. 4 is a control flowchart of the power steering apparatus according to the first embodiment.
FIG. 5 is a diagram showing a change in the number of rotations at the start of the hydraulic motor.
FIG. 6 is a control flowchart of the power steering apparatus according to the second embodiment.
FIG. 7 is a diagram illustrating a configuration of a main part related to a power steering apparatus according to a third embodiment.
FIG. 8 is a diagram showing a change in the number of rotations at the start of the hydraulic motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Forklift 14 Tire 16 Steering wheel 18 Direction lever 21 Hydraulic pump 22 Hydraulic motor 23 Priority valve 24 Power steering valve 26 Power steering cylinder 27 Tire angle sensor 28 Control part

Claims (4)

In a power steering apparatus having a hydraulic mechanism for transmitting an operation of a steering wheel to a steering wheel,
A hydraulic pump for supplying hydraulic oil to the hydraulic mechanism;
A hydraulic motor that drives the hydraulic pump to supply hydraulic oil to the hydraulic mechanism;
When the direction lever is switched to the travel position in a state where the hydraulic motor is stopped, the rotational speed of the hydraulic motor is set high at the time of start-up, and the amount of hydraulic oil supplied to the hydraulic mechanism is increased. A power steering apparatus comprising: a motor control circuit that controls the rotational speed of the hydraulic motor to a rotational speed corresponding to a steering operation after a certain time. A sensor for detecting the angle of the wheel of the steering wheel;
A hydraulic mechanism that transmits the operation of the steering wheel to the steering wheel;
A hydraulic pump for supplying hydraulic oil to the hydraulic mechanism;
A hydraulic motor that drives the hydraulic pump to supply hydraulic oil to the hydraulic mechanism;
When the direction lever is switched to the traveling position with the hydraulic motor stopped, or when the angular velocity obtained from the angle of the steered wheel detected by the sensor is greater than 0, the hydraulic motor at the start When the angular speed of the steered wheels is zero after a certain time , the rotational speed of the hydraulic motor is set to a lower rotational speed than at the start. And a motor control circuit that controls the rotational speed of the hydraulic motor to a rotational speed corresponding to the angular speed of the steering wheel when the angular speed of the steering wheel is greater than zero . A power steering device for an industrial vehicle that supplies hydraulic oil from one hydraulic pump to both a hydraulic mechanism for cargo handling and a hydraulic mechanism for power steering,
A sensor for detecting the angle of the wheel of the steering wheel;
A hydraulic mechanism that transmits the operation of the steering wheel to the steering wheel;
A hydraulic pump for supplying hydraulic oil to the hydraulic mechanism;
A hydraulic motor that drives the hydraulic pump to supply hydraulic oil to the hydraulic mechanism;
When the direction lever is switched to the traveling position with the hydraulic motor stopped, or when the angular velocity obtained from the angle of the steered wheel detected by the sensor is greater than 0, the hydraulic motor at the start When the angular speed of the steered wheels is zero after a certain time , the rotational speed of the hydraulic motor is set to a lower rotational speed than at the start. When the angular speed of the steering wheel is greater than 0 , an industrial vehicle having a power steering device including a motor control circuit that controls the rotational speed of the hydraulic motor to a rotational speed corresponding to the angular speed of the steering wheel . A hydraulic mechanism for loading and unloading work,
A hydraulic mechanism for power steering that transmits the operation of the steering wheel to the steering wheel;
A hydraulic pump for supplying hydraulic oil to the cargo handling hydraulic mechanism and the power steering hydraulic mechanism;
One hydraulic motor that drives the hydraulic pump to supply hydraulic oil to the cargo handling hydraulic mechanism and the power steering hydraulic mechanism;
A sensor for detecting the angle of the steering wheel;
When the direction lever is switched to the traveling position with the hydraulic motor stopped, or when the angular velocity obtained from the angle of the steered wheel detected by the sensor is greater than 0, the hydraulic motor at the start When the angular speed of the steered wheels is zero after a certain time , the rotational speed of the hydraulic motor is set to a lower rotational speed than at the start. When the angular speed of the steering wheel is greater than 0 , an industrial vehicle having a power steering device including a motor control circuit that controls the rotational speed of the hydraulic motor to a rotational speed corresponding to the angular speed of the steering wheel .

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