KR20010064586A - Method for preventing abnormal operation of electric folklift truck - Google Patents

Abstract

PURPOSE: A method for preventing malfunction in a forklift truck is provided to stop the forklift truck by deciding abnormality of a switching device while foreign material is inserted in a contact point of a magnetic contactor in the forklift truck. CONSTITUTION: A method for preventing malfunction of a forklift truck comprises a first stage deciding abnormality by a signal applied from an error detecting signal line; a second stage firstly recognizing abnormality of a contactor and a switching device according to a deciding result; a third stage secondly recognizing abnormality of forward contactor and a backward contactor according to the second stage; and a forth process stopping the forklift truck while outputting abnormal condition. Thereby, the method for preventing malfunction of the forklift truck induces normal travelling by preventing regard the abnormality of the forward or backward contactor as the abnormality of the switching device.

Description

How to prevent abnormal operation of electric forklifts {METHOD FOR PREVENTING ABNORMAL OPERATION OF ELECTRIC FOLKLIFT TRUCK}

The present invention relates to a method of preventing abnormal operation of an electric forklift, and more particularly, to prevent an operation of the vehicle from being stopped due to an error of a switching element when a foreign material is caught in a contact of a magnetic contactor of an electric forklift. The present invention relates to a method of preventing abnormal operation of a forklift truck.

In general, forklifts are used to lift and lower loads or to transport them to a desired position within a limited space and are widely used throughout the industry. Such forklifts are classified into an engine forklift and an electric forklift according to a power source. The engine forklift drives the hydraulic pump with the engine and provides all the power necessary for steering, driving and working with the hydraulic pressure generated by the hydraulic pump. The exhaust gas is generated and the noise is mainly used for outdoor work. . In addition, the electric forklift is operated by electricity supplied from a battery, has no exhaust gas, and has a low noise, and thus is mainly used for indoor work.

Hereinafter, an embodiment of a vehicle driving apparatus of a conventional electric forklift will be described in detail with reference to FIG. 1.

1 is a block circuit diagram showing a vehicle driving apparatus of a conventional electric forklift.

With the battery 1 connected to the vehicle and the line contactor 3 closed, the driver places the forward and backward switch 14 forward or backward to drive the vehicle, and the accelerator ( When stepping on 15), the control unit 13 connects the forward or reverse contactors 7, 8, and outputs a driving pulse (PWM pulse) to the switching element 9 to drive the vehicle in a normal state. Here, when the seat switch (not shown) and the line contactor 3 are operated while the battery 1 is connected, the short-circuit prevention circuit inside the control unit 13 causes the bypass contactor, the drive transistor, and the power transistor for the pump. For example, if the short circuit of the switching element 9 is investigated and the short circuit is shorted, the contact of the line contactor 3 is opened by stopping the supply of the excitation current of the line contactor 3. At this time, if the line fuse 2 which prevents the burnout of each component due to overload is burned out, the line contactor 3 is closed but the motor is not driven.

When the vehicle is operating normally, if foreign matter such as dust is inserted in the forward or reverse contactors 7, 8, the driving motor circuits 5, 6 are blocked so that the driving motor 5 does not drive, and the control unit ( 13) stops the operation of the vehicle after displaying the circuit abnormal state to the outside. The state at this time is the same as the state in which the error detection signal line 16 is low in a state in which there is no driving pulse and the switching element 9 is shorted (ie, short).

However, such a vehicle driving apparatus of a conventional electric forklift truck has a low signal in a state where an error detection signal line does not have a driving pulse due to the insertion of a foreign material such as dust into a forward or reverse contactor, and a switching element is short-circuited. In this case, there is a problem of incorrectly recognizing an abnormality of the forward or reverse contactors as an abnormality of the switching element.

In addition, when the abnormality of the forward or reverse contactor is incorrectly recognized as the abnormality of the switching element, the operation of the vehicle is stopped, thereby reducing work efficiency and extending work time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned general problems, and an object of the present invention is to determine whether an abnormality is caused by a foreign matter in a switching element or a forward or reverse contact point when detecting an error during driving of a vehicle. It is to provide a method of preventing abnormal operation of the electric forklift that can accurately recognize the abnormal state.

Another object of the present invention can recognize the abnormality of the switching element and the abnormality of the forward or reverse contactor by using the existing device as it is without installing a separate device, so that the driver can easily identify the recognized result The present invention provides a method of preventing abnormal operation of an electric forklift truck that induces a driver to remove foreign substances.

Another object of the present invention is to remove the foreign matter by repeating the operation of turning on / off the contact of the forward or reverse contactor when foreign matter is inserted into the forward or reverse contactor, if the foreign matter is not removed An object of the present invention is to provide a method of preventing abnormal operation of an electric forklift truck capable of removing foreign substances by displaying an abnormal state.

1 is a block circuit diagram showing a vehicle driving apparatus of a conventional electric forklift.

2A and 2B are flowcharts illustrating the operation according to the present invention.

♣ Explanation of symbols for the main parts of the drawing ♣

3: line contactor 5: amateur

6: field coil 7: forward contactor

8: Reverse contactor 9: Switching element

10: line contactor drive coil 11: forward contactor drive coil

12: reverse contactor drive coil 13: control unit

14: forward and backward switch 15: accelerator

16: Signal line for error detection

In order to achieve the above object, the present invention provides an error detecting signal line in a method of driving an electric forklift that rotates a motor by applying a driving pulse to a forward forward connector and a reverse reverse connector using a switching element. Determining whether there is an abnormality by a signal applied from the first recognition step; and recognizing the abnormality of the switching element and the abnormality of the contactor according to the determination result of the determination step; And a second recognizing step of recognizing the abnormality by distinguishing the abnormality of the forward contactor from the abnormality of the reverse contactor; and outputting the abnormal state to the outside and stopping the vehicle.

In addition, the first recognition step is a first confirmation step of confirming the current forward and backward switch according to the signal input from the forward and backward switch; and if the forward and backward switch is in the forward position according to the first confirmation step, the forward contactor is opened and the reverse direction Connecting the contactor, if the forward / backward switch is in the reverse position, opening the reverse contactor and connecting the forward contactor; and if the signal applied from the error detection signal line is an error signal, it is determined as an abnormality of the switching element. If the signal applied from the signal line is a normal signal, the first determination step of determining that the abnormality of the contactor.

In addition, the second recognition step is a second confirmation step of checking the current forward and backward switch according to the signal input from the forward and backward switch; and if the forward and backward switch is in the forward position according to the second confirmation step, the reverse contactor is opened and the forward Connecting the contactor, if the forward / backward switch is in the reverse position, opening the forward contactor and connecting the backward contactor; and according to the signal applied from the error detection signal line, And a second identification step of discriminating and identifying.

In addition, the second identification step may include repeating the operation of turning on / off the contact of the forward contactor when the error is the abnormality of the forward contactor, and repeating the operation of turning on / off the contact of the reverse contactor if the error of the reverse contactor; Characterized in that it comprises a.

Hereinafter, a preferred embodiment of the abnormal operation prevention method of the electric forklift according to the present invention will be described in detail with reference to the accompanying drawings.

2A and 2B are flowcharts illustrating the operation according to the present invention.

First, when the driver connects the battery 1 to the vehicle and turns on the key switch while the driver is seated on the seat, the controller 13 applies power to the line contactor driving coil 10 to turn on the line contactor 3. Connect (202). At this time, when the seat switch (not shown) and the line contactor 3 are operated while the battery 1 is connected, the short circuit prevention circuit inside the control unit 13 checks whether the switching element 9 is shorted and if the line is shorted, The contact of the line contactor 3 is opened by stopping the supply of the excitation current of the contactor 3, and the line contactor 3 remains connected if it is not shorted.

Next, the control unit 13 determines whether or not the driver has stepped on the accelerator 15 pedal after the forward or backward switch 14 is positioned forward or backward (204). If it is determined that the driver has not pressed the accelerator 15, the driver returns to the step 202 and waits for the driver to press the pedal of the accelerator 15 while the line contactor 3 is continuously connected. When the pedal has pressed the accelerator 15, it is determined whether the forward or backward switch is input to determine whether it is a forward switch or a reverse switch (206). Here, if the driver presses the accelerator 15 pedal or enters the forward / backward switch before turning on the seat switch and the key switch, a warning is displayed and the operation of the vehicle is stopped.

As a result of the determination in step 206, if it is determined that the forward switch is input, the control unit 13 applies power to the forward contactor driving coil 11 to connect the contacts of the forward contactor 208 (208), and switches A driving pulse (that is, a PWM pulse) for turning on / off the element 9 is output to advance the vehicle in a forward direction according to the stepping angle of the pedal of the accelerator 15 (210). In addition, when it is determined in step 206 that the reverse switch is input, the controller 13 applies power to the reverse contactor driving coil 12 to connect the contacts of the reverse contactor 8 (212). In operation 210, a driving pulse (ie, a PWM pulse) for turning on / off the switching element 9 is output and the vehicle is advanced in the reverse direction according to the stepped angle of the pedal of the accelerator 15. Here, the direction change to the forward or reverse direction of the vehicle is changed direction by changing the connection of the forward contactor 7 or the reverse contactor 8 contact and reversing the direction of the power applied to the armature 5 of the traveling motor. Do this.

While the vehicle is driving in the forward or reverse direction, the controller 13 determines whether an error signal input to the error detection signal line 16 is input or not, and determines whether it is a normal signal or an error signal (214). When foreign matter such as dust or the like is inserted into the forward contactor 7 or the reverse contactor 8 and the circuit of the traveling motor is cut off, the signal of the error detection signal line 16 is input to the controller 13 as follows.

≪Table≫

Switching element Steady state signal Signal when foreign object is inserted Signal when switching element short ON LOW LOW LOW OFF HIGH (battery) LOW LOW

As a result of the determination in step 214, if the signal input to the control unit 13 is a normal signal (i.e., if the signal input from the error detection signal line 16 is LOW while the switching element 9 is on), then If the signal input to the control unit 13 is an error signal (that is, if the signal input from the error detection signal line 16 is LOW when the switching element 9 is in the OFF state) The control unit 13 determines whether the current forward or backward switch 14 is in the forward or backward position according to the signal input from the forward / backward switch (218).

As a result of the determination in step 218, if the forward and backward switch 14 is in the forward position, the control unit 13 cuts off the power applied to the forward contactor driving coil 11 to open the contact of the forward contactor 7. In operation 220, the reverse contactor driving coil 12 is powered to connect the contacts of the reverse contactor 8 (222). As a result of the determination in the step 218, if the forward and backward switch 14 is in the reverse position, the control unit 13 cuts off the power applied to the reverse contactor drive coil 12 to open the contacts of the reverse contactor 8. In operation 224, power is applied to the forward contactor driving coil 11 to connect the contacts of the forward contactor 7 (222).

After the above steps 222 and 226, the controller 13 determines whether an error signal input to the error detection signal line 16 is input to determine whether it is a normal signal or an error signal (226). As a result of the determination, when the error signal is output, the forward contactor 7 and the reverse contactor 8 are in an error state, indicating that the switching element 9 is abnormal or that both the forward contactor 7 and the reverse contactor 8 are abnormal. In response, the abnormal state is displayed to the outside (228), and the vehicle is stopped (230). As a result of the determination in step 226, if the normal signal is output when the forward / backward switch 14 is in the forward position, it is determined that the forward contactor 7 is abnormal, and the forward / backward switch 14 is in the reverse position. If the normal signal is outputted, the reverse contactor 8 determines that there is an error. After the normal signal is output in the step 226, the control unit 13 again determines whether the current forward or backward switch 14 is in the forward or backward position according to the signal input from the forward or backward switch (232) ).

As a result of the determination in step 232, if the forward and backward switch 14 is in the forward position, the control unit 13 cuts the power applied to the reverse contactor drive coil 12 to open the contact of the reverse contactor 8. In operation 234, a power is applied to the forward contactor driving coil 11 to connect the contacts of the forward contactor 7 (236). Next, the controller 13 determines whether the error signal input to the error detection signal line 16 is input or not, and determines whether it is a normal signal or an error signal (238).

As a result of the determination of the step 238, when the normal signal is output, since the abnormality is cured between the opening of the forward contactor 7 and the connection process, the operation ends after returning to the normal driving state (240). As a result of the determination of the step 238, when the error signal is output, the abnormality is not healed, so that the power applied to the forward contactor driving coil 11 is cut off to open the contact of the forward contactor 7 (242). Power is applied to the forward contactor driving coil 11 to connect the contacts of the forward contactor 7 (244). At this time, the driver or the designer sets the number of repetitions for the opening and connecting process of the contactor 7 forward. The reason for repeating the opening and connecting process of the forward contactor 7 contact is that foreign matter may be removed by repeating the opening and connecting process of the contact. Next, the controller 13 determines whether or not the process of opening and connecting the contactor of the forward contactor 7 has been repeated a predetermined number of times (246). As a result of the determination, if the set number of times has not been performed, the process returns to the step 238 to repeat the subsequent steps, and if it is determined that the set number of times has been performed, the opening and connecting process of the forward contactor 7 is repeated. Since the foreign matter is not removed, the abnormal state of the forward contactor 7 is displayed to the outside for the driver to recognize (248).

As a result of the determination in step 232, if the forward and backward switch 14 is in the reverse position, the control unit 13 cuts off the power applied to the forward contactor driving coil 11 to open the contact of the forward contactor 7. In operation 250, power is supplied to the reverse contactor driving coil 12 to connect the contacts of the reverse contactor 8 (252). Next, the controller 13 determines whether the error signal input to the error detection signal line 16 is input or not, and determines whether it is a normal signal or an error signal (254).

As a result of the determination of the step 254, when the normal signal is output, since the abnormality is cured between the opening and the connecting process of the reverse contactor 8, the operation ends after returning to the normal driving state (256). As a result of the determination in step 254, when the error signal is output, the abnormality is not healed. Then, the power applied to the reverse contactor driving coil 12 is cut off to open the contact point of the reverse contactor 8 (258). Power is applied to the reverse contactor driving coil 12 to connect the contacts of the reverse contactor 8 (260). At this time, the driver or the designer sets the number of repetitions for the opening and connecting process of the reverse contactor (8) contact. The reason why the opening and connecting process of the reverse contactor 8 is repeated is that foreign matter may be removed by repeating the opening and connecting process of the contact. Next, the controller 13 determines whether the opening and connecting processes of the reverse contactor 8 contacts are repeated as many times as the set number of times (262). As a result of the determination, if the set number of times has not been performed, the process returns to the step 254 to repeat the subsequent steps, and if it is determined that the set number of times has been performed, the opening and connecting processes of the reverse contactor 8 are repeated. Since the foreign matter has not been removed, the abnormal state of the reverse contactor 8 is displayed to the outside for the driver to recognize (248). After displaying the abnormal state of the forward contactor 7 or the reverse contactor 8 to the outside, the controller 13 stops the operation of the vehicle and ends the operation (264).

The abnormal operation prevention method according to the present invention can be equally applied to a hydraulic motor as well as a traveling motor.

The above embodiments are merely illustrative of the preferred embodiments of the present invention, and the scope of application of the present invention is not limited to these, and may be appropriately changed within the scope of the same idea. For example, the shape and structure of each component specifically shown in the embodiment of the present invention can be modified. In addition, the present invention can be widely used in various ways.

As described above, according to the method of preventing an abnormal operation of the electric forklift according to the present invention, it is determined whether the abnormality is caused by the abnormality of the switching element or the foreign matter in the forward or reverse contact point when the error of the vehicle is detected. By recognizing, there is an effect that can prevent the wrong of the forward or reverse contactor to the error of the switching element to induce the normal running.

In addition, since the abnormality of the switching element and the abnormality of the forward or reverse contactors can be recognized by using the existing device as it is without installing a separate device, the cost can be reduced.

In addition, when a foreign material is inserted into the forward or reverse contactor, the foreign material can be removed by repeating the operation of turning on / off the contact of the forward or reverse contactor. By displaying, the foreign matter can be removed by the driver.

Claims (4)

In a driving method of an electric forklift truck which rotates a motor by applying a driving pulse to a forward forward connector and a reverse reverse contactor using a switching element, Determining an abnormality by a signal applied from an error detection signal line; A first recognition step of discriminating and recognizing an abnormality of a switching element and an abnormality of a contactor according to the determination result of the determination step; A second recognizing step of recognizing the abnormality of the contactor by distinguishing the abnormality of the forward contactor from the abnormality of the reverse contactor according to the first recognizing step; Outputting the abnormal state to the outside and stopping the vehicle; Method for preventing abnormal operation of the electric forklift, comprising a. The method of claim 1, wherein the first recognition step A first checking step of checking a current forward / backward switch according to a signal input from the forward / backward switch; Connecting the forward contactor and the reverse contactor when the forward and backward switch is in the forward position according to the first checking step, and opening the reverse contactor and connecting the forward contactor when the forward and backward switch is at the backward position; And a first determining step of determining that the signal applied from the error detection signal line is an error signal, and determining that the switching element is abnormal. How to prevent abnormal operation of the electric forklift truck. The method of claim 1, wherein the second recognition step A second checking step of checking a current forward / backward switch according to a signal input from the forward / backward switch; If the forward and backward switch is in the forward position according to the second checking step, opening the reverse contactor and connecting the forward contactor; if the forward and backward switch is in the reverse position, opening the forward contactor and connecting the backward contactor; And a second identification step of discriminating and identifying the abnormality of the forward and the reverse contactors according to the signal applied from the signal line for error detection. The method of claim 3, wherein the second identification step Repeating the operation of turning on / off the contact of the forward contactor if the abnormality of the forward contactor, and repeating the operation of turning on / off the contact of the reverse contactor of the reverse contactor of the reverse contactor. How to prevent abnormal operation of electric forklifts.