JP3841403B2 - Electric steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric steering device that steers a steered wheel by a steering motor in response to a steering operation.
[0002]
[Prior art]
Conventionally, in various industrial vehicles such as forklifts, an electric steering device that drives a steering motor in accordance with an operation of a steering handle by an operator and steers the steering wheel has been adopted. In some cases, there is no mechanical connection mechanism between the two.
[0003]
This type of electric steering apparatus is configured, for example, as shown in the block diagram of FIG. 5 includes a steering wheel rotation sensor 1 that detects the number of rotations of the steering wheel, a steering motor 2 that operates the steering mechanism, a control device 3 that controls the steering motor 2, and the steering motor 2. And a steering angle sensor 4 that detects a steering angle of a steered wheel whose direction is changed by an actuated steering mechanism.
[0004]
The control device 3 performs control to drive the steering motor 2 in accordance with the number of rotations of the steering wheel detected by the steering wheel rotation sensor 1 and the actual steering angle of the steering wheel detected by the steering angle sensor 4. It is like that. Here, the control device 3 determines the steering speed at which the steering wheel is steered according to the number of rotations of the steering wheel, and the steering motor 2 is driven to rotate so that the steering wheel is steered at this steering speed. To do. That is, control is performed to rotate the steering motor 2 faster so that the steering wheel is steered at a higher steering speed as the steering handle is rotated and the rotational speed from the neutral state of the steering handle increases. That is, assuming that the rotation speed of the steering wheel is θs, the steering wheel steering speed is ωt, and the proportionality coefficient is K, the relationship between the steering wheel rotation speed θs and the steering wheel steering speed ωt is
ωt = K × θs (1)
It can be expressed by the formula
[0005]
[Problems to be solved by the invention]
As described above, in the conventional electric steering apparatus, the steering speed ωt of the steering wheel is determined in relation to the rotation speed θs of the steering wheel, so that the intention of the operator who rotates the steering wheel is always reflected. Therefore, there is a problem that the direction of the steering wheel cannot be changed. That is, even if the operator slowly rotates the steering handle 12 to turn the vehicle slowly or quickly rotates the steering handle 12 to turn quickly, the steering wheel steering speed ωt is set. Since the operation is not followed, the operation feeling is poor, and as a result, the operator may feel stressed or the work efficiency may not be increased.
[0006]
Further, when traveling while holding the steering handle 12 at an arbitrary position such as when going straight ahead, the change in the direction of the steering wheel due to the shake of the steering handle 12 or the unevenness of the road surface is made as small as possible, and the direction of the steering wheel is changed greatly. In some cases, there is a desire to minimize the number of rotation operations of the steering handle 12 as much as possible.
[0007]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electric steering apparatus configured to realize a satisfactory operation feeling of the steering wheel.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention according to claim 1 is directed to an electric steering device that drives a steering motor in accordance with a rotation operation of the steering wheel and changes the direction of the steering wheel. Steering wheel detection means for detecting the steering wheel, steering angle detection means for detecting the actual steering angle of the steered wheel, and rotation of the steering wheel by calculation based on the rotational speed detected by the steering wheel rotation detection means. A calculation means for determining a steering speed for steering the steered wheel according to a number of time change rates, a time change rate of an actual steering angle of the steered wheel detected by the steering angle detection means, and the Control means for driving and controlling the steering motor so that the steering speed determined by the calculation means coincides with the steering speed.
[0009]
In the invention according to claim 1, the calculating means determines the steering speed as a set value when the time change rate of the rotation speed of the steering wheel is within a predetermined numerical range, and the time change rate When it is not within the predetermined numerical range, the steering speed is determined so as to increase as the time change rate of the rotation speed of the steering wheel increases.
[0010]
The number of rotations of the steering wheel in the present invention is the number of rotations based on the steering wheel neutral position, that is, the position of the steering wheel where the vehicle goes straight, and the steering wheel steering speed in the present invention. Includes an angular velocity at which the steered wheels are steered and a peripheral velocity.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a forklift as an example of an industrial vehicle will be described with reference to the drawings. FIG. 1 is an external perspective view of a forklift provided with the electric steering apparatus of the present embodiment, FIG. 2 is a block diagram showing a control system of the electric steering apparatus of the present embodiment, and FIG. 3 is a steering system according to the present embodiment. It is explanatory drawing which shows the relative relationship between the rotational speed of a steering wheel, and the steering speed of a steering wheel.
[0012]
The forklift shown in FIG. 1 is a three-wheeled forklift that includes a pair of left and right front wheels at the front of the vehicle body 11 and a rear wheel at the rear of the vehicle body 11. The pair of left and right front wheels are drive wheels driven by a forklift that is driven by a travel motor (not shown), and the rear wheels are steering wheels 13 that turn the forklift. A driver's seat on which an operator is seated is provided at the center of the vehicle body 11, and a steering handle 12 is disposed in front of the driver's seat.
[0013]
A steering motor 2 is installed above the steering wheel 13, and a steering mechanism 14 driven by the steering motor 2 is connected to the steering wheel 13. The direction of the steered wheels 13 can be changed by the operation of the driven steering mechanism 14. Note that a mechanical coupling mechanism is not provided between the steering wheel 12 and the steering wheel 13, and the steering wheel 13 can be rotated by 180 ° based on the straight traveling state.
[0014]
As shown in FIG. 2, the electric steering apparatus according to the present embodiment includes a steering wheel rotation sensor 1 as a steering wheel rotation detection unit that detects the rotational speed θs of the steering wheel 12, and the actual steering angle θt of the steering wheel 13. A steering angle sensor 4 as a steering angle detection means for detecting the control signal, and a control device 3 composed of a microcomputer or the like.
[0015]
The handle rotation sensor 1 has an encoder that is directly connected to the rotation shaft of the steering handle 12, and a detection signal is output from the encoder when the steering handle 12 is rotated. . Further, the steering angle sensor 4 has a potentiometer that detects the steering angle θt in a range of 90 ° clockwise and counterclockwise based on the straight traveling state (steering angle 0 °) of the steering wheel 13. A detection signal corresponding to the steering angle θt of the steered wheel 13 is output from the potentiometer.
[0016]
As shown in FIG. 3, the control device 3 is configured to calculate a target steering speed ωto of the steered wheel 13 based on a signal from an encoder of the steering wheel rotation sensor 1, and a target determined by the calculation unit 5. The addition / subtraction unit 6 for deriving the deviation between the steering speed ωto and the signal from the potentiometer of the steering angle sensor 4, that is, the time change rate of the actual steering angle θt, and the deviation derived by the addition / subtraction unit 6 become zero. Thus, a drive unit 7 that drives and controls the steering motor 2 is provided. Further, a memory 8 in which data used for calculation described below is stored is attached to the calculation unit 5, and the calculation unit 5 reads out necessary data from the memory 8 and performs calculation. .
[0017]
The calculation unit 5 determines the target steering speed so that the relative relationship between the rotational speed ωs of the steering handle 12 and the target steering speed ωto of the steered wheels 13 becomes the relationship shown in FIG. That is, the calculation unit 5 first derives a rotation speed (angular velocity) ωs of the steering handle 12 by performing time differentiation on the detection signal of the steering wheel rotation sensor 1, that is, the rotation speed θs of the steering handle 12, and rotates the steering handle 12. When the speed ωs is in the range of 0 ≦ ωs <ωs1,
ωto = K1 × ωs (2)
When the calculation represented by the equation (A in FIG. 3) is performed and the rotational speed ωs of the steering handle 12 is in the range of ωs1 ≦ ωs <ωs2,
ωto = ωt1 (3)
When the calculation represented by the equation (B in FIG. 3) is performed and the rotational speed ωs of the steering handle 12 is in the range of ωs2 ≦ ωs <ωs3,
ωto = K2 × ωs (4)
(C in FIG. 3) and the rotational speed ωs of the steering handle 12 is in the range of ωs ≧ ωs3,
ωto = ωt2 (5)
The calculation represented by the equation (D in FIG. 3) is performed to determine the target steering speed ωto. Here, ωt1 and ωt2 are steering speed values set in advance, ωs1, ωs2, and ωs3 are steering wheel rotation speed values that are set in advance, and K1, K2 (> K1) are proportional coefficients.
[0018]
The adder / subtractor 6 derives an actual steering speed (angular velocity) ωt of the steered wheel 13 by time-differentiating the detection signal from the steering angle sensor 4, that is, the actual steering angle θt. A deviation between the direction speed ωt and the target steering speed ωto derived by the calculation unit 5 is derived.
[0019]
Then, the drive unit 7 drives and controls the steering motor 2 so that the deviation derived by the addition / subtraction unit 6 becomes zero, that is, the actual steering speed ωt and the target steering speed ωto coincide.
[0020]
Therefore, when the rotational speed ωs obtained by time-differentiating the rotational speed θs of the steering handle 12 is in the range of ωs2 ≦ ωs <ωs3, the target steering speed ωto of the steered wheels 13 is a preset value ωt1. Therefore, the steering motor 2 is driven to rotate as in the prior art. On the other hand, when the rotational speed ωs obtained by time-differentiating the rotational speed θs of the steering handle 12 is not in the range of ωs2 ≦ ωs <ωs3, the steering wheel is calculated by the calculation represented by the formula (2) or (4). The target steering speed ωto of the steering wheel 13 increases as the rotational speed ωs of the steering wheel 12 increases. Then, the steering motor 2 is rotationally driven so that the steering wheel 13 is steered at the steering speed ωt of the steering wheel 13 according to the rotational speed ωs of the steering handle 12. However, in order to prevent danger due to the steering speed ωt of the steered wheels 13 becoming too fast, the target steering speed ωto is determined to a preset value ωt2 when the rotational speed ωs is in the range of ωs ≧ ωs3. The steering wheel 13 is steered within a safe steering speed range.
[0021]
As described above, according to the present embodiment, when the rotational speed ωs of the steering handle 12 is not in the range of ωs2 ≦ ωs <ωs3, the steering wheel 13 can be operated faster if the operator rotates the steering handle 12 faster. If the operator turns the steering handle 12 slowly, the steering wheel 13 is steered slowly, so that the steering handle 12 has a good feeling of operation and the operator can turn as desired.
[0022]
In this embodiment, the proportionality coefficient K1 when the rotational speed ωs of the steering wheel 12 is slow (0 ≦ ωs <ωs1) is set small, and the proportionality coefficient K2 when the rotational speed ωs is fast (ωs ≧ ωs3) is set large. Therefore, when the rotational speed ωs of the steering wheel 12 is slow, the steering speed ωt of the steering wheel 13 is further decreased, and when the rotational speed ωs of the steering handle 12 is fast, the steering speed of the steering wheel 13 is further increased. ωt becomes faster. Therefore, it is possible to effectively suppress the change in the direction of the steering wheel 13 due to the fluctuation of the steering handle 12 or the unevenness of the road surface when traveling with the steering handle 12 held at an arbitrary position. By rapidly rotating the steering wheel 13, the direction of the steered wheel 13 can be greatly changed with fewer operations.
[0023]
Incidentally, the steering wheel rotational speed values ωs1, ωs2, ωs3, the steering speed values ωt1, ωt2, etc. stored in the memory 8 may be changed. For example, an electric steering device as shown in FIG. be able to.
[0024]
That is, in addition to the above-described embodiment, a setting change switch 9 that can be operated by the operator is further provided, and the steering wheel rotation speed values ωs1, ωs2, ωs3, the steering speed values ωt1, ωt2, and the like set by the setting change switch 9 The data is stored in the memory 8. By doing in this way, each operator can perform the setting according to his liking, and it becomes possible to realize a more suitable operation feeling.
[0025]
In the above embodiment, the actual steering angle θt of the steered wheels 13 is directly detected by the steering angle sensor 4. However, when high-precision control is not necessary, the steering motor 2 The applied voltage value and current value may be detected, and the steering angle of the steered wheels 13 may be calculated by a calculation process based on the detected values.
[0026]
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.
[0027]
【The invention's effect】
According to the present invention, since the steering wheel is steered at a steering speed corresponding to the time change rate of the rotation speed of the steering wheel, the operator can quickly rotate the steering wheel to steer the steering wheel quickly. In addition, the steering wheel can be slowly rotated to steer the steering wheel. As a result, the operator can turn the vehicle as desired.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a forklift provided with an electric steering device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a control system of the electric steering device according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a relative relationship between the rotation speed of the steering wheel and the steering speed of the steering wheel in the embodiment of the present invention.
FIG. 4 is a block diagram showing a control system in another embodiment of the electric steering apparatus according to the present invention.
FIG. 5 is a block diagram showing a control system in a conventional electric steering apparatus.
[Explanation of symbols]
1 Handle rotation sensor (handle rotation detection means)
2 Steering motor 3 Control device 4 Steering angle sensor (steering angle detection means)
5 Calculation unit (calculation means)
6 Addition / subtraction unit (control means)
7 Drive unit (control means)
8 Memory 9 Setting change switch 11 Car body 12 Steering handle 13 Steering wheel 14 Steering mechanism

Claims (1)

In an electric steering device that drives a steering motor in accordance with a rotation operation of the steering wheel and changes the direction of the steering wheel, a steering wheel rotation detecting means that detects the number of rotations of the steering wheel, and an actual steering angle of the steering wheel A steering angle detecting means for detecting the steering wheel and a steering speed for steering the steered wheel according to a time change rate of the rotational speed of the steering handle by a calculation based on the rotational speed detected by the steering wheel rotation detecting means. The steering means so that the time change rate of the actual steering angle of the steered wheel detected by the steering angle detecting means matches the steering speed determined by the calculating means. Control means for driving and controlling the motor, and the calculation means is configured such that the time change rate of the rotation speed of the steering wheel is within a predetermined numerical range. In this case, the steering speed is determined as a set value, and when the time change rate is not within the predetermined numerical range, the steering speed becomes a larger value as the time change rate of the rotation speed of the steering wheel increases. An electric steering apparatus characterized by determining as follows .

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