JP2002347640A - Electric power steering device in cargo handling vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a power steering motor and a controller thereof from over-heating and burning. SOLUTION: It is judged from a switch position of a directional lever whether or not the lever is in the neutral state (S1); if the judgment result is YES, it is judged whether or not a count value of a timer counter arrives at 3s being a set time (S4); and if the result is YES, an output control of a power steering motor by a motor driver is stopped (S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus for a cargo-handling vehicle having no mechanical connection between a steering wheel and a steering mechanism.

[0002]

2. Description of the Related Art Conventionally, some electric power steering devices for cargo handling vehicles such as forklifts do not have a mechanical coupling structure between a steering wheel and a steering mechanism. The device is configured, for example, as shown in FIG.

That is, as shown in FIG. 4, a rotation angle of a steering wheel provided on a vehicle body such as a forklift is detected by an operation angle sensor 1 comprising a potentiometer or the like, and an actual steering angle of a steering mechanism is detected. The target steering angle is detected by an actual steering angle sensor 2 composed of a potentiometer or the like, and the target steering angle is derived by calculation by a target steering angle calculation unit 3 from the rotation operation angle detected by the operation angle sensor 1. At this time, since the rotation operation angle of the steering wheel and the target steering angle are in a proportional relationship, the target steering angle can be derived by multiplying the detected rotation operation angle by a constant.

Then, a difference between the target steering angle and the steering angle detected by the actual steering angle sensor 2 is calculated by an addition / subtraction unit 4, and the difference is multiplied by a predetermined proportional coefficient by a proportional element calculation unit 5. The output of the proportional element calculation unit 5 is provided to a motor driver 6 composed of a chopper circuit or an inverter circuit, and the output of the power steering motor 7 is controlled by the motor driver 6. In this way, control is performed so that the steering angle by the actual steering angle sensor 2 matches the target steering angle.

However, since friction and reaction force exist between the actual road surface and the tires of the cargo handling vehicle, the power is determined based on the value obtained by multiplying the difference between the target steering angle and the steering angle by the proportional coefficient. When the steering motor 7 is controlled,
The steering angle of the actual steering mechanism cannot be completely matched with the target steering angle, and a steady deviation occurs between the actual steering angle and the target steering angle.

If such a steady deviation occurs continuously, a residual current corresponding to the steady deviation will continue to flow through the motor 7 even when the steering wheel is not operated. 6 may cause overheating and burning of the controller.

Therefore, usually, as shown in FIG. 4, the time integral value of the difference between the target steering angle and the steering angle is calculated by an integral element operation unit 8.
The steady-state error is eliminated by adding the integration result (integration element) by the integration element calculation unit 8 to the calculation result of the proportional element calculation unit 5 by the addition unit 9, and the output of the addition unit 9 is used as a motor driver. 6, the power steering motor 7 is controlled to eliminate the above-mentioned problem due to the residual current.

[0008]

However, the friction and reaction force generated between the actual road surface and the tires of the cargo handling vehicle differ depending on the type of the tire and the condition of the road surface.
Since these frictions and reaction forces are greatly different between when the load is loaded and when the load is not loaded, it is generally difficult to find the optimal value of the integral element in consideration of all the states of such cargo handling vehicles. It is impossible to make the above-mentioned stationary deviation completely zero.

Also, in a vehicle other than a forklift, if the tires fall into a groove and the tires are locked and the vehicle cannot be steered, current continues to flow through the motor 7. The controller including the motor 7 and the motor driver 6 may be overheated or burnt.

Accordingly, an object of the present invention is to protect a power steering motor and its controller from overheating and burning.

[0011]

In order to achieve the above object, the present invention detects the rotation of a steering wheel and controls a power steering motor based on the detected value. In a cargo handling vehicle that steers, a traveling direction setting unit provided in the vehicle to set the traveling direction of the vehicle to forward and backward and a neutral state, and a neutral detection unit that detects setting of the neutral state by the traveling direction setting unit. Wherein the control means comprises:
The control of the power steering motor is stopped when the neutral state is detected by the neutral detecting means.

According to this configuration, when the neutral detecting means detects that the traveling direction of the vehicle is set to the neutral state by the traveling direction setting means, the traveling direction of the vehicle is set to the neutral state. During this time, there is no need to drive the power steering motor to perform power assist, and the control means stops the control of the power steering motor. Therefore, while the traveling direction of the vehicle is set to the neutral state by the traveling direction setting means, the control of the power steering motor is stopped, so that the current to the motor continuously flows during that time, and the motor and its controller are controlled. Can be prevented from overheating and burning.

The present invention also relates to a cargo handling vehicle in which a rotation of a steering wheel is detected and a control means controls a power steering motor based on the detected value to steer a steering mechanism. A traveling direction setting means for setting the traveling direction of the vehicle to forward and backward and a neutral state, a neutral detecting means for detecting the setting of the neutral state by the traveling direction setting means, and a preset from the detection of the neutral state by the neutral detecting means. A timer counter that counts the set time that has been set, wherein the control means stops controlling the power steering motor when the counting of the set time by the timer counter ends.

According to such a configuration, it is determined whether or not the counting of the set time by the timer counter is completed.
The traveling direction setting means can reliably determine whether the traveling direction of the vehicle is set to the neutral state. If it can be determined that the traveling direction of the vehicle is set to the neutral state, the power steering by the control means is performed. Since the control of the motor is stopped, the current to the power steering motor is cut off when the vehicle is in the neutral state in the traveling direction, so that the motor and its controller can be more reliably prevented from overheating and burning.

Further, according to the present invention, the cargo handling vehicle is a reach type forklift, and the traveling direction setting means is operated in a forward direction or a backward direction by a driver, and automatically shifts to the neutral state by releasing the operation. It is an accelerator lever that performs

According to such a configuration, when the driver releases the operation of the accelerator lever, the traveling direction of the vehicle is automatically set to the neutral state by the traveling direction setting means, and the neutral state is detected by the neutral detecting means. Since the current to the power steering motor is cut off, overheating and burning of the motor and its controller can be prevented more reliably.

Further, the present invention is characterized in that the cargo handling vehicle is a counterbalance type forklift, and the traveling direction setting means is a directional lever.

According to such a configuration, when the driver sets the directional lever to the neutral state, the current to the power steering motor is cut off when the neutral state is set, so that the motor and its controller are overheated or burned out. Can be more reliably prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a counterbalance type forklift as a cargo handling vehicle will be described with reference to FIGS. However,
FIG. 1 is a perspective view of a counterbalanced forklift according to an embodiment of the present invention, FIG. 2 is a block diagram of a control system of the counterbalanced forklift, and FIG. 3 is a flowchart for explaining the operation.

As shown in FIG. 1, a counterbalance type forklift 100 according to this embodiment has a driver seat 111.
Vehicle body 110 provided with a vehicle body 1 and the like.
10 and a mast device 120 provided at a front portion of the vehicle body 110. The mast device 120 includes a pair of masts 121 provided at a front portion of the vehicle body 110 and both masts 121.
Each of them is constituted by a pair of forks 123 attached via a lift bracket 122.

An accelerator pedal 113 and a brake pedal 114 are disposed on a floor portion 112 of the driver's seat 111. In front of the driver's seat 111, a steering wheel 115, a directional lever 117 as a traveling direction setting means, and various other components are provided. Panel 11 on which the operating levers and the like are arranged
6 are provided.

A battery, a traveling motor, and a hydraulic motor for cargo handling are provided inside the vehicle body 110, and each of these motors performs traveling and cargo handling, respectively.

The directional lever 117 in front of the driver's seat 111 is provided with a neutral detecting means (not shown) for detecting a neutral state from the switching position of the directional lever 117. The detecting means detects whether or not the position of the directional lever 117 is set to the neutral state. By operating the directional lever 117, it is possible to set the traveling direction of the counterbalanced forklift 100, that is, the forward and reverse travels and the neutral state. For example, the direction of travel of the vehicle body 110 can be set to the backward direction when the directional lever 117 is tilted backward, the forward direction when the directional lever 117 is tilted forward, and to a neutral state at an intermediate position between them.

Next, the control system of the electric power steering device of the counterbalance type forklift 100 will be described with reference to FIG.

That is, as shown in FIG. 2, an operation angle sensor 21 is provided as operation angle detecting means for detecting the rotation operation angle of the handle 115 of the counterbalance type forklift 100, and the actual steering angle of the steering mechanism is determined. An actual steering angle sensor 22 is provided as actual steering angle detecting means for detecting, and both of the sensors 21 and 22 are constituted by, for example, potentiometers.

The target steering angle is calculated by the target steering angle calculator 23 from the rotation operation angle detected by the operation angle sensor 21. Here, since the rotation operation angle of the steering wheel 115 and the target steering angle are in a proportional relationship, it is possible to derive the target steering angle by multiplying the rotation operation angle detected by the operation angle sensor 21 by a constant. it can.

Further, the difference between the target steering angle and the steering angle detected by the actual steering angle sensor 22 is calculated by the addition / subtraction unit 25.
The difference is multiplied by a predetermined proportional coefficient by a proportional element calculating unit 26, and a time integral value of a difference between the target steering angle and the steering angle is calculated by an integral element calculating unit 27. The integration result (integration element) by the integration element calculation unit 27 is added to the calculation result of the proportional element calculation unit 26.

The output of the adder 28 is supplied to a motor driver 30 comprising a chopper circuit or an inverter circuit, and the output of the power steering motor 31 is controlled by the motor driver 30. Thus, the steering angle by the actual steering angle sensor 22 is changed. Control is performed so as to match the target steering angle.

On the other hand, as described above, the directional lever 117 provided at the front of the driver's seat 111 is set to the neutral state, and when this neutral state is detected by the neutral detecting means 33, the timer counter 34 When the counting starts and a preset time (for example, 3 s) is counted and the counting of the timer counter 34 ends, the output control of the power steering motor 31 by the motor driver 30 is stopped. . Such a motor driver 3
The process of stopping the output control of the power steering motor 31 by 0 corresponds to control means in the present invention. still,
The timer counter 34 has a directional lever 117.
Is cleared when the vehicle is set in a forward or reverse state other than the neutral state.

Next, the operation will be described with reference to the flowchart of FIG. As shown in FIG. 3, it is determined from the switching position of the directional lever 117 whether or not the vehicle is in the neutral state (S1). If the determination result is NO, that is, the directional lever 117 is set to the forward or backward state. For example, the timer counter 34 is cleared (S2), the output control of the power steering motor 31 is performed by the motor driver 30, and the power steering motor 31 is driven (S3).
Return to 1.

On the other hand, if the decision result in the above step S1 is YES, that is, if the directional lever 117 is in the neutral state, the timer counter 34 operates, and whether or not the count value of the timer counter 34 has reached the set time of 3 s is determined. Is determined (S4), and the determination result is N
If it is O, the count of the timer counter 34 is continued (S5), and then the process proceeds to the above-described step S3.

If the result of the determination in step S4 is YES, it can be determined that the timer counter 34 has completed counting (counting up) for the set time of 3 s. The output control of the power steering motor 31 by the driver 30 is stopped (S6), and the process returns to step S1.

As described above, the directional lever 11
When the timer counter 34 starts counting and ends counting the set time after the switching position 7 is in the neutral state, it can be determined that the directional lever 117 is set to the neutral state. While the lever 117 is set in the neutral state, it is not necessary to drive the power steering motor 31 to perform power assist, and the output control of the power steering motor 31 is stopped by the motor driver 30.

At this time, by adding the integration result (integration element) by the integration element calculation section 27 to the calculation result of the proportional element calculation section 26 by the addition section 28, a steady state between the actual steering angle and the target steering angle is obtained. Can be reduced to some extent, but not completely zero,
A residual current based on this deviation flows through the power steering motor 31. However, by stopping the output control of the power steering motor 31 by the motor driver 30 as described above while the directional lever 117 is set to the neutral state,
It is possible to prevent the residual current based on this deviation from continuing to flow to the power steering motor 31.

Therefore, according to the above-described embodiment, while the switching position of the directional lever 117 is set to the neutral state, the output control of the power steering motor 31 by the motor driver 30 is stopped, so that the direct Prevents overheating and burnout of the power steering motor 31 and the like due to continuous flow of current (residual current) to the power steering motor 31 while the switching position of the positional lever 117 is set to the neutral state. can do.

The suspension of the output control of the power steering motor 31 is delayed by the count time (= 3 s) of the timer counter 34, for example, when the switching position of the directional lever 117 is switched from forward to reverse. The directional lever 117 is momentarily brought into the neutral state, but it is possible to prevent the output control of the power steering motor 31 from being stopped in response to the momentary neutral state and the steering wheel from becoming ineffective.

In the above embodiment, the output control of the power steering motor 31 by the motor driver 30 is stopped when the timer counter 34 counts up the set time (here, 3 s). This set time is not particularly limited to the above-mentioned 3 s. Further, without providing such a timer counter 34,
The output control of the power steering motor 31 by the motor driver 30 may be stopped when the switching position of the directional lever 117 is set to the neutral state.

In the above-described embodiment, the case where the traveling direction setting means is the directional lever 117 has been described. However, the traveling direction setting means is not limited to such a directional lever 117. is there. For example, two switches, forward and reverse, are arranged on a front panel 116 in front of the driver's seat 111,
By turning on either the forward or reverse switch, the traveling direction of the vehicle body 110 can be set to forward or reverse. If neither switch is turned on, the vehicle can be set to the neutral state, and the state of these switches is detected. Thus, a configuration for detecting the neutral state may be adopted.

Further, in the above-described embodiment, the case where the present invention is applied to the counterbalance type forklift 100 has been described. However, the scope of the present invention is not limited to this, and the reach type forklift and other cargo The present invention can be applied to a vehicle having a traveling direction setting means capable of setting a vehicle body to a neutral state.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.

[0041]

As described above, according to the first aspect of the present invention, when it is detected by the neutral detecting means that the traveling direction of the vehicle is set to the neutral state by the traveling direction setting means, during that time, Eliminates the need to drive the power steering motor for power assist,
Since the control of the power steering motor is stopped by the control means, the control of the power steering motor is stopped while the traveling direction of the vehicle is set to the neutral state. It is possible to prevent the motor and its controller from being overheated or burned out due to the flow.

According to the second aspect of the present invention, whether or not the traveling direction of the vehicle is set to the neutral state by the traveling direction setting means is determined by whether or not the counting of the set time by the timer counter is completed. When it can be determined that the traveling direction of the vehicle is set to the neutral state, the control of the power steering motor by the control means is stopped.
By interrupting the current to the power steering motor in the neutral state in the traveling direction of the vehicle, overheating and burning of the motor and its controller can be more reliably prevented.

Further, the suspension of the output control of the power steering motor is delayed by the count time of the timer counter, so that, for example, even when the traveling direction of the vehicle is switched from forward to reverse, even if the vehicle temporarily enters the neutral state, the neutral state is maintained. It is possible to prevent the output control of the power steering motor from being stopped in response to the momentary neutral state and the steering wheel from becoming ineffective.

According to the third aspect of the present invention, when the driver releases the operation of the accelerator lever, the traveling direction of the vehicle is automatically set to the neutral state by the traveling direction setting means, and the neutral detecting means is set. As a result, the neutral state is detected and the current to the power steering motor is cut off, so that the motor and its controller can be more reliably prevented from overheating and burning.

According to the fourth aspect of the present invention, when the driver sets the directional lever to the neutral state, the current to the power steering motor at the time of setting the neutral state is cut off. It is possible to more reliably prevent overheating and burning of the controller.

[Brief description of the drawings]

FIG. 1 is a perspective view of a counterbalanced forklift according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control system according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation according to the embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Operation angle sensor (operation angle detection means) 22 Actual steering angle sensor (actual steering angle detection means) 30 Motor driver (control means) 31 Power steering motor 33 Neutral detection means 34 Timer counter 100 Counterbalanced forklift 117 Directional lever (Progress direction setting means)

Claims (4)

[Claims] 1. A cargo handling vehicle for detecting rotation of a steering wheel and controlling a power steering motor based on the detected value to steer a steering mechanism. A traveling direction setting unit that sets forward, backward, and neutral states; and a neutral detection unit that detects setting of a neutral state by the traveling direction setting unit, wherein the control unit detects the neutral state by the neutral detection unit. An electric power steering apparatus for a cargo-handling vehicle, wherein control of the power steering motor is sometimes stopped. 2. A cargo handling vehicle which detects rotation of a steering wheel and controls a motor for power steering based on the detected value to steer a steering mechanism. A traveling direction setting means for setting forward, backward, and neutral states; a neutral detecting means for detecting setting of the neutral state by the traveling direction setting means; and a preset time set from the detection of the neutral state by the neutral detecting means. An electric power steering apparatus for a cargo-handling vehicle, wherein the control means stops the control of the power steering motor when the counting of the set time by the timer counter ends. 3. The cargo handling vehicle is a reach-type forklift, and the traveling direction setting means is operated by a driver in a forward direction or a reverse direction, and the accelerator lever automatically shifts to the neutral state when the operation is released. The electric power steering apparatus for a cargo handling vehicle according to claim 1 or 2, wherein: 4. The electric power steering apparatus according to claim 1, wherein the cargo handling vehicle is a counterbalance type forklift, and the traveling direction setting means is a directional lever.