KR20030056637A - Method for controlling steering of electromotive forklift truck by use of angle sensor - Google Patents

Abstract

PURPOSE: A rotation control method of an electromotive forklift is provided to control wider rotation than a former electromotive forklift by continuously detecting a rotating angle of the forklift through an angle sensor and controlling a driving pulse to be fed to each traveling motor. CONSTITUTION: Driving pulse duties of left/right traveling motors are preset corresponding to a rotating angle of an electromotive forklift. In rotating left/right rear wheels of the electromotive forklift by adjusting a steering handle, the rotating angle is sensed by an angle sensor(S607). The preset duties of the driving pulses are calculated corresponding to the rotating angle. The driving pulses for the traveling motors are reduced based on the calculated duties(S615). Thereby, the rotation control range is wider than a former electromotive forklift.

Description

Rotation control method of electric forklift using angle sensor {METHOD FOR CONTROLLING STEERING OF ELECTROMOTIVE FORKLIFT TRUCK BY USE OF ANGLE SENSOR}

The present invention relates to a rotation control method of an electric forklift, and more particularly, an electric motor using an angle sensor that can prevent damage to the driving motor by appropriately adjusting the load of the driving motor according to the rotational angle during left / right turning in the electric forklift. It relates to a rotation control method of a forklift.

In general, forklifts are classified into engine-based forklifts using fuel and electric forklifts using electric power according to their power sources. Here, the electric forklift (electric forklift) is operated by the electricity supplied from the battery, there is no exhaust gas and the noise is mainly used in the indoor working environment.

1 is a view showing each constituent means for performing a rotation control in a conventional general electric forklift in relation to the present invention, the steering wheel 11, the left driving motor 12, the right driving motor 13, the control unit (14), hydraulic pump motor (15), pressure switch (16), angle sensor (17), left front wheel (18), right front wheel (19), left rear wheel (20), right rear wheel (21) And a left current detector 22 and a right current detector 23.

Referring to Figure 1 describes the rotation control process in the conventional electric forklift as follows.

First, when the driver attempts to turn left or right by manipulating the steering wheel 11, the pressure switch 16 connected to the steering wheel 11 detects the steering wheel operation and transmits a steering signal corresponding thereto. To apply. Then, the control unit 14 increases the drive pulse output of the hydraulic pump motor 15 in response to the steering signal, the hydraulic pump motor 15 is based on the increased drive pulse from the control unit 14 of the rear wheel of the electric forklift (20, 21) is mechanically rotated by hydraulic pressure.

Figures 2a to 2c is a diagram showing the state of the rear wheels 10, 11 of the electric forklift that is rotated through this process divided into straight (Fig. 2a), left turn (Fig. 2b), right turn (Fig. 2c). .

On the other hand, when the driver rotates the steering wheel 11 at a predetermined angle or more during the left / right rotation of the electric forklift, and the rotation angle of the rear wheels 10 and 11 accordingly exceeds 75 degrees, the angle sensor 17 operates. By generating a rotation detection signal, the control unit 14 receives this rotation detection signal to selectively control the driving pulses of the respective driving motors (12, 13). That is, the angle sensor 17 mounted on the conventional general electric forklift operates only when the rotation angle of the rear wheels 20 and 21 is 75 degrees or more, and outputs a detection signal accordingly.

For example, if the rotation angle becomes 75 degrees or more in the process of turning the electric forklift to the right, and the rotation detection signal from the angle sensor 17 is transmitted to the control unit 14, the control unit 14 may be configured as a left driving motor ( A driving pulse corresponding to 75% is applied to the accelerator input (not shown) as shown in 12), and then the driving pulse is reduced to the right driving motor 13 so as to be 0% with respect to the accelerator input. Similarly, when turning left, a driving pulse corresponding to 75% of the accelerator input is applied to the right driving motor 13, and the driving pulse is reduced to the left driving motor 12 so as to be 0% of the accelerator input.

Controlling the driving pulses of each of the driving motors 12 and 13 in this way prevents slippage of the rear wheels 20 and 21 during left and right rotations, and at the same time unbalances the load on the driving motors 12 and 13. The purpose is to prevent. That is, when the electric forklift turns left, the load on the left driving motor 12 is relatively high, and when the electric forklift turns right, the load on the right driving motor 13 is relatively high. The driving motors 12 and 13 are adaptively controlled.

However, in the conventional general electric forklift, the driving pulse control as described above is performed only when the rotation angle is 75 degrees or more.

3 is a view illustrating this, the angle sensor 17 mounted on a conventional general electric forklift as shown in the same drawing, each rear wheel 20, 21 is rotated more than 75 degrees to the left or right. In this case, the detection signal is generated only. Therefore, the control unit 14 is designed to control the driving pulses of the driving motors 12 and 13 only when the rotation angle is 75 degrees or more. That is, in FIG. 3, the regions in which the steering control is possible are the regions 1 and 4, and the rotation control is not performed in the regions 2 and 3.

Therefore, when the area 2 and the area 3 of FIG. 3, that is, the electric forklift are rotated at an angle of less than 75 degrees, only the directions of the rear wheels 20 and 21 are switched and the driving pulses of the respective driving motors 12 and 13 are not adjusted. Because of this, a slip phenomenon of the vehicle occurs, and a problem occurs that the driving motor in the rotating direction is overloaded.

FIG. 4 is a graph measuring the amateur current flowing through the left and right traveling motors 12 and 13 according to the conventional rotation control method.

As shown in the figure, when the right turn of the vehicle is overloaded on the right driving motor 13, there is a problem that the likelihood of damage of the right driving motor 13 and the right power module is increased accordingly, each driving motor There is a problem that the amount of current flowing through the (12, 13) is increased, the battery consumption is also increased and the working time of the electric forklift is reduced by that amount.

Therefore, the present invention has been made to solve the above problems of the prior art, by using an angle sensor to continuously detect the rotation angle of the electric forklift and control the driving pulse applied to each driving motor according to the conventional electric forklift The purpose of the present invention is to provide a rotation control method of an electric forklift truck using an angle sensor capable of controlling a rotation for a wider rotation angle than that of the electric forklift.

The present invention according to a preferred embodiment for achieving the above object,

A method for controlling rotational driving by detecting a rotational angle through an angle sensor during left / right rotation of an electric forklift, the driving pulse duty of the left / right traveling motor corresponding to the rotational angle of the electric forklift Setting up a first step; A second step of sensing a rotation angle through the angle sensor when the left / right rear wheel of the electric forklift is rotated by a steering wheel; A third step of calculating a duty of the predetermined driving pulse corresponding to the rotation angle; And a fourth step of reducing a driving pulse of the driving motor in the driving direction based on the calculated duty.

1 is a view showing each component associated with the rotation control in a general electric forklift.

Figure 2a to 2c is a view showing a state of the wheel according to the rotation direction of the electric forklift.

3 is a view showing a rotation area that can be controlled in a conventional electric forklift.

Figure 4 is a graph measuring the amateur current flowing in the left / right running motor when the right turn in the conventional electric forklift.

Figure 5 is a view showing each constituent means of the electric forklift truck suitable for performing the rotation control method according to the present invention.

6 is a flowchart illustrating a rotation control process of the electric forklift according to the present invention.

<Explanation of symbols for the main parts of the drawings>

11: steering wheel 12: left driving motor

13: right driving motor 14: control unit

15: hydraulic pump motor 16: pressure switch

18: Left front wheel 19: Right front wheel

20: left rear wheel 21: right rear wheel

22: left current detector 23: right current detector

51: analog angle sensor 52: A / D conversion unit

53: display unit

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

Figure 5 is a view showing each constituent means of the electric forklift truck suitable for performing the rotation control method according to the present invention, the overall constituent means shown in the same figure and its function is the same as that of FIG. However, in FIG. 5 according to the present embodiment, the conventional angle sensor 17 shown in FIG. 1 is changed to an analog angle sensor 51 having a variable resistance type. That is, the angle sensor 17 provided in the conventional electric forklift is configured as a digital type sensor to generate a sensing signal only when a specific angle (75 °) or more, while the analog angle sensor 51 used in the present invention is The linear sensing signal is continuously output according to the rotation angle. The analog sensing signal output from the analog angle sensor 51 is converted into digital data through the A / D converter 52 and transmitted to the controller 14. Here, the above-described analog angle sensor 51 outputs a sensing signal for the rotation angle of the left and right rear wheels 20 and 21 as a value within a range of, for example, 0V to 5V, and the A / D converter 52 This is converted into a digital value in the range of 0 to 1024 and transmitted to the controller 14.

Then, the controller 14 determines the rotation direction and the rotation angle of the electric forklift based on the digital value provided through the A / D conversion unit 52 and generates driving pulses corresponding to the respective driving motors 12, 13).

In detail, first, the controller 14 determines that the electric forklift is turning right when the digital value of the sensing signal converted and provided by the A / D converter 52 is less than 512. It is judged to turn left. Then, the duty of the driving pulses applied to each of the driving motors 12 and 13 is controlled to a predetermined value corresponding to the digital value, wherein the value of the driving pulse corresponding to the rotation angle corresponds to the rotation direction. As a value that can minimize the overload of the traveling motor to be, it can be easily calculated by an experiment according to the capacity of the traveling motor in the initial design stage.

On the other hand, the duty of the driving pulse corresponding to the rotation angle detected from the control algorithm and the analog angle sensor 51 may be built in the program form in the control unit 14 as in the present embodiment, alternatively a separate storage means (eg For example, the controller 14 may be configured to store the data in a ROM, and then read and execute the same in the controller 14.

5 is a means for displaying the rotation angle of the electric forklift under the control of the control unit 14, and the user displays the rotation angle of the electric forklift through the display unit 53. This can be confirmed, thereby helping to drive safely.

6 is a flowchart illustrating a rotation control process of the electric forklift according to the present invention. The overall process will be described in detail with reference to the accompanying drawings.

First, if the driver attempts to turn left / right by rotating the steering wheel 11 while the electric forklift is driving straight (step S601) (step S603), the pressure switch 16 detects the steering signal according to the control unit ( 14, the control unit 14 applies a driving pulse to the hydraulic pump motor 15 to mechanically rotate the left and right rear wheels 20, 21 of the vehicle by hydraulic pressure (step S605).

At this time, the analog angle sensor 51 detects the rotation angles of the left and right rear wheels 20 and 21 and generates a sensing signal of a predetermined level corresponding thereto, and the A / D converter 52 converts the sensing signals. A predetermined digital value is converted and provided to the control unit 14 (step S607).

Meanwhile, the controller 14 calculates the rotation direction of the electric forklift based on the digital value provided from the A / D conversion unit 52 and calculates the rotation angle, and then displays the result through the display unit 53 to allow the driver to do this. Reference is made (step S609).

Subsequently, the controller 14 determines whether the calculated rotation angle is greater than or equal to a predetermined predetermined angle (for example, 30 °) (step S611), which is the speed of the vehicle when the rotation angle of the electric forklift is large. It is to decelerate and improve stability.

If, as a result of the determination in the above-described step (S611), when the rotation angle of the electric forklift is more than a predetermined predetermined angle, the field current applied to each of the driving motors 12, 13 is first increased in correspondence to the rotation angle of the vehicle. By doing so, the torque of the vehicle is increased, but the speed of the vehicle is lowered to induce safe driving during rotation (step S613). Here, the magnitude of the field current increased corresponding to the rotation angle of the electric forklift is calculated by an experiment according to the capacity of the motor in the design of the electric forklift as described above, and stored in the control unit 14 or stored in a separate storage means. Applicable

On the other hand, if the speed of the vehicle is decelerated through such a process, the control unit 14 is a driving motor having a larger load based on the rotation angle of the electric forklift truck calculated in step S609 described above, that is, driving corresponding to the rotation direction. By reducing the drive pulses applied to the motor to a predetermined duty (step S615), the load imbalance between each of the traveling motors 12 and 13 is eliminated. At this time, it is preferable that the reduction of the driving pulse for the driving motor is adjusted in steps of 2 ㎲ or less so that the electric forklift can maintain a stable driving state.

On the contrary, if the rotation angle of the electric forklift is less than a predetermined angle (for example, 30 °), the field current applied to each of the driving motors 12 and 13 is determined. By adjusting stepwise only the driving pulses applied to the driving motor whose load is greater, that is, the driving motor corresponding to the rotation direction without adjusting, in step S615 (step S615), the load between the driving motors 12 and 13 is similarly applied. This will eliminate the imbalance.

As a result, the control unit 14 calculates the rotation angle of the vehicle based on the sensing signal provided from the analog angle sensor 51 when the electric forklift turns left / right, and accordingly calculates the field current and the driving pulse of the driving motor. It can be controlled appropriately.

As described above, according to the present invention, it is possible to apply a wider range of rotation control than a conventional electric forklift truck, thereby enabling stable rotational travel, and eliminating the load imbalance between each driving motor during rotation. And there is an effect that can also prevent damage to the motor drive module. In addition, by reducing the sum of the load current applied to each driving motor has an effect that can extend the use time of the battery of the electric forklift.

Claims (5)

In the method for controlling the rotation running by detecting the rotation angle through the angle sensor when the left / right rotation of the electric forklift, A first step of presetting a driving pulse duty of a left / right traveling motor corresponding to a rotation angle of the electric forklift; A second step of sensing a rotation angle through the angle sensor when the left / right rear wheel of the electric forklift is rotated by a steering wheel; A third step of calculating a duty of the predetermined driving pulse corresponding to the rotation angle; And a fourth step of reducing a driving pulse of the driving motor in the driving direction based on the calculated duty. The method of claim 1, The second step, If the sensed rotation angle is greater than the predetermined predetermined angle to increase the field current applied to the left / right driving motor further comprising the step of slowing down the traveling speed of the electric forklift, the rotation control method of the electric forklift using an angle sensor . The method of claim 1, Always angle sensor is an analog angle sensor for generating an analog sensing signal, The third step, A thirty-first step of converting the signal sensed in the second step into a predetermined digital value; A thirty-second step of calculating a rotation direction and a rotation angle based on the converted digital value; And a thirty-third step of calculating the duty of the predetermined driving pulse in response to the rotation angle. The method of claim 3, wherein The 32nd process, Rotating control method of the electric forklift using an angle sensor further comprising the step of displaying the calculated rotation angle through the display means. The method according to any one of claims 1 to 4, The fourth step, Rotation control method of the electric forklift using an angle sensor, characterized in that for gradually reducing the drive pulse for the driving motor in the driving direction in units of less than 2㎲.