JP2007217071A - Lifting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine the presence or absence of the abnormality of a valve and safely lower a lifting device even if the valve is defective. <P>SOLUTION: When a control device 5 determines that a motor 22 is rotated in the down direction of an operation stand 9 based on the result of the detection by a rotation detector 23 when a down instruction is not given thereto (down switch 15 is not operated), it determines that the valve 24 is defective. Then, the control device 5 regeneratively regenerates the motor 22 and displays an error on a display 17. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an elevating device that performs an operation by elevating an elevating tool up and down, and particularly relates to an apparatus that operates by hydraulic pressure.

  Conventionally, in an industrial vehicle such as a forklift, hydraulic pressure is used to operate a lifting device that lifts and lowers a lifting tool (fork, work table, etc.) up and down, and a valve is provided in a hydraulic circuit of the lifting device. The flow of hydraulic oil is controlled by the above. By using a valve, for example, it is possible to easily change the movement of the lifting tool. However, if dust (pipe wear powder, etc.) in the hydraulic fluid is clogged, the valve will not operate normally, and the elevator will move up and down. The tool may not be able to move up and down or may move abnormally. Therefore, when using a valve, it is necessary to consider the possibility of a valve failure, and it is important that the failure can be detected and dealt with early.

  Therefore, as described in Patent Document 1, for example, the position of the spool of the valve is detected, and when the detected actual position is deviated from the target position, the supply of hydraulic pressure is stopped because the valve is abnormal. Technology to do is considered. In addition, as described in Patent Document 2, there is a technique in which the presence or absence of an abnormality is determined based on a current value for an electromagnetic valve, and an alarm is activated if there is an abnormality. Furthermore, when an abnormality occurs in the valve, for example, as described in Patent Document 3, a technique for controlling the flow of hydraulic oil with a separately provided auxiliary valve is also considered.

Japanese Utility Model Publication No. 5-64199 JP 2002-37600 A JP 2003-104699 A

  In the configuration in which a sensor is attached to a valve in order to detect an abnormality, there is an advantage that the presence / absence of an abnormality can be individually determined by preparing sensors for the number of valves. However, it is necessary to take into consideration that erroneous detection of the sensor, particularly erroneous detection due to abnormality of the valve, for example, it is necessary not to make a mistake in determining whether there is an abnormality even if the sensor makes an erroneous detection. Also, as described in Patent Document 3, if an auxiliary valve is provided, even if an abnormality occurs in the valve, the operator will not be left at a high place. It is necessary to consider the possibility of failure.

  An object of the present invention is to make it possible to accurately determine the presence or absence of an abnormality in a valve and to safely lower a lifting tool even when the valve is abnormal.

  In order to achieve the above object, according to the present invention, a cylinder supporting a lifting tool and a pump connected to a motor are connected by hydraulic piping, and when an ascending instruction is given, hydraulic oil stored in a tank is supplied to the pump. When the lowering tool is given, the hydraulic oil discharged from the cylinder is returned to the tank via the pump when the cylinder is shortened. In the lifting device for lowering the lifting tool, the lifting device is provided in a hydraulic pipe connecting the rotation detector for detecting the rotation direction and rotation speed of the motor and the cylinder and the pump, and from the cylinder to the pump. A valve that can be switched between a closed state that interrupts the flow of hydraulic oil and an open state that allows the flow of the hydraulic oil, and the ascending or descending instruction and the rotation detector. A control device for controlling the motor and the valve according to a detection result. The control device switches the valve to the open state when the lowering instruction is given, and when the lowering instruction is not given. The valve is switched to the closed state, and it is determined whether or not the rotation direction detected by the rotation detector is a direction in which the lifting tool is lowered, and the valve is rotating in the direction in which it is lowered. Is configured to determine that the valve is abnormal.

  According to the present invention, it is possible to easily switch between lowering and stopping of the lifting tool by switching the state of the valve, and it is assumed that the valve cannot be switched to the closed state in the open state. It is possible to reliably recognize the abnormality. That is, the valve should be closed when no lowering instruction is given, but the valve is open when it is determined that the motor is rotating in the direction of lowering the lifting tool. Therefore, it can be determined that there is an abnormality in the valve. Therefore, necessary measures such as warning to the operator can be promptly performed based on the determination result. Furthermore, the rotation detector provided for controlling the motor can also be used as the rotation detector in the present invention, and in this way, safety can be ensured while reducing costs.

  In the above configuration, when the lowering instruction is not given, the control device is such that the detected rotation direction is a direction in which the lifting tool is lowered, and the detected rotation speed is a predetermined value or more. If there is, the motor can be regeneratively controlled.

  In this way, the motor is regeneratively controlled in the event of an abnormality in which the valve remains open, so that the lifting tool can be lowered at a controlled safe lowering speed. Can be reliably prevented.

In the present invention, the ascending and descending instructions for the lifting device are a method of instructing the operator by operating the operating device provided in the lifting device, or a signal representing an instruction from the outside to the communication device provided in the lifting device. It is sufficient to adopt a method of transmitting the message.
Further, when determining an abnormality, not only whether or not the rotation direction detected by the rotation detector is the direction in which the lifting tool is lowered, but also the state in which the rotation direction is the direction in which the lifting tool is lowered. Can be determined together with whether or not the rotation speed is higher than a predetermined value in a state where the rotation direction is the direction in which the lifting tool is lowered. In this way, it is possible to prevent erroneous determination due to detection error or disturbance in the rotation detector, and it is possible to more accurately determine whether there is an abnormality in the valve.

  As described above, according to the present invention, it is possible to reliably switch the lowering and lowering of the lifting tool by switching the valve state. Even if the valve cannot be switched to the closed state, the abnormality Can definitely be recognized. Furthermore, in the present invention, the lifting tool can be safely lowered by performing regenerative control of the motor when the valve is abnormal.

  Hereinafter, an embodiment in which the present invention is applied to a battery forklift will be described with reference to the drawings.

  As shown in FIG. 1, the battery forklift according to this embodiment includes a pair of left and right straddle legs 2 extending rearward at the rear part of a vehicle body 1, and a rear wheel 3 is provided at the front end part of each straddle leg 2. ing. As shown in FIGS. 1 and 2, a front wheel 4 is provided at the center of the front portion of the vehicle body 1, various hydraulic devices to be described later are mounted on the right side, and a control device 5 is mounted on the left side. Note that an inverter 6 is mounted integrally with the control device 5, and the motor 22 described later is controlled by the inverter 6 being controlled by the control device 5. Further, as shown in FIG. 2, a battery 7 is mounted on the rear portion of the vehicle body 1, and the battery 7 is used as a drive source of the battery forklift.

  As shown in FIGS. 1 and 2, a mast 8 is erected on the rear portion of the vehicle body 1, and a driver's cab 9 on which an operator rides is provided on the mast 8 so as to be lifted and lowered. The mast 8 is provided with a pair of left and right lift cylinders 10. When the lift cylinder 10 is extended, the cab 9 is raised. Conversely, when the lift cylinder 10 is shortened, the cab 9 is lowered. The driver's cab 9 is supported by a mast 8 and a lift cylinder 10, but in addition to these, the lifting device for cargo handling according to this embodiment includes various hydraulic devices provided in the vehicle body 1, a control device 5, an inverter 6, and a battery 7. It is comprised by.

  The cab 9 is provided with a pair of left and right forks 11 extending rearward on the floor, and as shown in FIG. 1, the front wall 4 is rotated as a steering wheel on the front wall to change its direction. A handle 12 for operating and an operation box 13 for raising and lowering the cab 9 are provided. The operation box 13 includes an up switch 14 for instructing to raise the cab 9 and a down switch 15 for instructing to descend. When the operator performs a switch operation, the up instruction or the down instruction is controlled as a signal. It is transmitted to the device 5. Further, the front wall of the cab 9 includes an accelerator 16 for adjusting the traveling speed by rotating the front wheels 4 as driving wheels, and a display 17 for displaying a display visible to the operator on the cab 9. It has been. Such a driver's cab 9 and various devices including the fork 11 provided in the driver's cab 9 correspond to the lifting tool in the present invention.

  The hydraulic device provided in the vehicle body 1 mainly includes a tank 20 for storing hydraulic oil, a pump 21, a motor 22 connected to the pump 21, a rotation sensor 23 attached to the motor 22, and a flow of hydraulic oil. It consists of a valve 24 for controlling the pressure and hydraulic piping connecting the devices. As shown in FIG. 3, the tank 20 and the pump 21, the pump 21 and the valve 24, and the valve 24 and the lift cylinder 10 are respectively connected by hydraulic piping. In this embodiment, a hydraulic pipe that supplies hydraulic oil from the tank 20 to the lift cylinder 10 and a hydraulic pipe that returns the hydraulic oil from the lift cylinder 10 to the tank 20 are shared.

  The rotation sensor 23 detects the rotation direction and rotation speed of the motor 22 and transmits the detection result to the control device 5 as a signal. The valve 24 is an electromagnetic valve that can be switched between a raised position and a lowered position, and is controlled by the control device 5. That is, when the built-in solenoid is excited by the control device 5, the valve 24 is in the lowered position, and only the flow of hydraulic oil from the lift cylinder 10 to the pump 21 is allowed. When the excitation is stopped by the control device 5, the valve 24 returns to the raised position by the built-in spring, allowing the flow of hydraulic oil from the pump 21 to the lift cylinder 10, and blocking the flow from the lift cylinder 10 to the pump 21. It becomes.

  As shown in FIG. 3, the control device 5 is supplied with signals from the rotation sensor 23 together with signals from the up switch 14 and the down switch 15, and the control device 5 receives the inverter 6 and the valve based on these signals. 24 is controlled. Further, these signals are used in the control device 5 to determine abnormality of the valve 24 described later.

  When the lift switch 14 is operated by an operator, the control device 5 does not excite the valve 24 and the inverter 22 is rotated so that the motor 22 rotates forward (rotates in the direction to raise the cab 9) at a predetermined rotational speed. The pump 21 is driven by the motor 22. When the motor 22 is subjected to power running control in this manner, the pump 21 discharges hydraulic oil sucked from the tank 20 toward the valve 24, and the discharged hydraulic oil is supplied to the lift cylinder 10 through the valve 24. As a result, the lift cylinder 10 extends, and the cab 9 rises at a rising speed corresponding to the rotational speed of the motor 22. When the operation of the raising switch 14 is stopped, the control device 5 stops the motor 22. If the valve 24 is normally in the raised position, the lift cylinder 10 stops extending and the cab 9 stops.

On the other hand, when the lowering switch 15 is operated by the operator, the control device 5 excites the valve 24. As a result, when the valve 24 is in the lowered position, the hydraulic oil from the lift cylinder 10 due to the shortening due to the weight of the cab 9 or the load flows into the pump 21 through the valve 24, and the pump 21 reverses (lowers the cab 9). Rotate in the direction). Along with this, the motor 22 also reverses, but the control device 5 performs regenerative control of the motor 22 via the inverter 6 and charges the battery 7 with the electric power generated by the motor 22. As a result, the cab 9 descends at a descending speed corresponding to the rotational speed of the motor 22. When the operation of the lowering switch 15 is stopped, the control device 5 stops the regeneration control of the motor 22 and stops the excitation of the valve 24. If the valve 24 returns to the raised position normally, the shortening of the lift cylinder 10 stops and the cab 9 stops.
As will be described later, the control device 5 performs regenerative control of the motor 22 even when the valve 24 is abnormal and the cab 9 is lowered.

  The control device 5 determines whether or not the valve 24 is abnormal based on the input signal, that is, whether or not the valve 24 cannot be switched from the lowered position to the raised position. When it is determined that the valve 24 is abnormal, a display to that effect is displayed on the display 17. The control device 5 displays various information useful for the operator on the display 17 in addition to the abnormality of the valve 24.

  Hereinafter, the control flow in this embodiment will be further described.

  As shown in FIG. 4, when the rotation direction and rotation speed of the motor 22 are taken into the control device 5 from the rotation sensor 23 (S1), the control device 5 determines whether or not the ascent switch 14 is operated (S2). . If the ascent switch 14 is operated (YES in S2), the control device 5 performs power running control of the motor 22 to raise the cab 9 (S3). If the up switch 14 is not operated (NO in S2), the control device 5 next determines whether or not the down switch 15 is operated (S4). If the lowering switch 15 is operated (YES in S4), the control device 5 excites the valve 24 (S5), regeneratively controls the motor 22 and lowers the cab 9 (S6).

If the lowering switch 15 is not operated (NO in S4), as shown in FIG. 4, the control device 5 determines whether the rotation direction of the motor 22 is the reverse rotation direction (S7). If the rotation direction of the motor 22 is the reverse rotation direction (YES in S7), the control device 5 counts the duration of the state of the reverse rotation direction, and whether or not this duration is equal to or greater than a predetermined threshold (for example, 1s). Is determined (S8). If the duration is equal to or greater than the threshold (YES in S8), the control device 5 determines that the valve 24 is abnormal and sets an error flag (S9). In other words, the fact that the motor 22 continues to reverse while the valve 24 is not excited means that the valve 24 cannot be switched to the raised position, and hydraulic oil flows from the lift cylinder 10 to the pump 21 through the valve 24. Therefore, the control device 5 determines that the valve 24 is abnormal.
When the rotation direction of the motor 22 is the normal rotation direction (NO in S7) and when the duration of the state in which the rotation direction of the motor 22 is the reverse rotation direction is less than the threshold value (NO in S8), the control device 5 does not set an error flag.

Further, as shown in FIG. 4, the control device 5 determines whether or not the rotational speed of the motor 22 is equal to or higher than a predetermined threshold (for example, 500 rpm) (S10). (YES in S10), the motor 22 is regeneratively controlled (S11). As a result, the cab 9 is lowered at the controlled lowering speed. Here, if the rotational speed of the motor 22 is set to a low speed by regenerative control, the cab 9 can be lowered at a slow lowering speed.
When the rotation speed of the motor 22 is less than the threshold value (NO in S10), the control device 5 does not perform regenerative control of the motor 22.

Subsequently, as shown in FIG. 4, the control device 5 determines whether or not the error flag is set (S12). If the error flag is set (YES in S12), the valve 17 on the display 17 is abnormal. An error display to the effect is displayed (S13). Even if the up switch 14 or the down switch 15 is operated and the cab 9 is raised or lowered, even if any switch is not operated and the motor 22 is stopped, the error flag is already set. If so, an error is displayed on the display 17 so that the operator on the cab 9 can know the abnormality of the valve 24 by seeing this.
The error flag may be cleared, for example, when the valve 24 is repaired or when the battery forklift is started after the valve 24 is repaired.

  According to such an embodiment, if the valve 24 is normal, the cab 9 can be reliably switched between rising and lowering and stopping the cab 9 by switching the state of the valve 24. Even if the oil in the hydraulic oil is clogged or the spring is damaged and the valve 24 remains in the lowered position and becomes abnormal, the motor 22 is regeneratively controlled by the control device 5, so that the cab 9 is safe. Can be lowered. In addition, it is possible to definitely determine that there is an abnormality in the valve 24, and the operator can be notified by an error display on the display 17. In addition, since the rotation direction and the rotation speed detected by the rotation sensor 23 provided for controlling the motor 22 are used, it is not necessary to provide a separate sensor for abnormality determination, and the cost can be reduced. it can.

In the above-described embodiment, an error is displayed on the display 17 based on the error flag in the control device 5, but in addition to this, for example, an error may occur when a buzzer provided in the cab 9 is operated. Flags can be used.
In the above embodiment, the error flag is set according to the duration of the state in which the rotation direction of the motor 22 is the reverse rotation direction. However, instead of or in addition to this, the rotation direction of the motor 22 is set. An error flag can be set when the rotational speed in the state of reverse rotation is greater than or equal to a threshold value. In this way, the presence or absence of abnormality in the valve 24 can be determined more accurately.

1 is a rear perspective view of a battery forklift according to an embodiment of the present invention. 1 is a front perspective view of a battery forklift according to an embodiment of the present invention. It is a system diagram of the lifting device for cargo handling according to an embodiment of the present invention. It is a control flowchart of the Example of this invention.

Explanation of symbols

5 Control device 6 Inverter 7 Battery 8 Mast 9 Driver's cab 10 Lift cylinder 13 Operation box 14 Up switch 15 Down switch 17 Display 20 Tank 21 Pump 22 Motor 23 Rotation sensor 24 Valve

Claims (2)

The cylinder supporting the lifting tool and the pump connected to the motor are connected by hydraulic piping, and when an ascending instruction is given, the hydraulic oil stored in the tank is supplied via the pump to extend the cylinder. When the lifting / lowering tool is raised and a lowering instruction is given, the lifting / lowering device lowers the lifting / lowering tool by returning the hydraulic oil discharged from the cylinder to the tank via the pump when the cylinder is shortened. In
A rotation detector that detects the rotation direction and rotation speed of the motor, and a hydraulic pipe that connects the cylinder and the pump, and allows a closed state and a flow that shut off the flow of hydraulic oil from the cylinder to the pump. A valve that can be switched to an open state, and a controller that controls the motor and the valve according to the ascending instruction or the descending instruction and a detection result by the rotation detector,
The control device switches the valve to the open state when the lowering instruction is given, and switches the valve to the closed state when the lowering instruction is not given. It is determined whether or not the detected rotation direction is a direction in which the lifting / lowering tool is lowered, and if it is rotating in the lowering direction, it is determined that the valve is abnormal. apparatus.   If the rotation direction detected is a direction in which the lifting tool is lowered when the lowering instruction is not given, and the detected rotation speed is a predetermined value or more, the control device The elevating device according to claim 1, wherein the elevating device performs regenerative control.

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