JP3784308B2 - Electric power steering system for cargo handling vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering device for a cargo handling vehicle having lifting / lowering means for lifting and lowering a loaded load.
[0002]
[Prior art]
Conventionally, there is an order picking truck as a cargo handling vehicle, and an electric power steering device in this order picking truck is, for example, a machine between a steering handle operated by an operator and a steering mechanism including steerable steering wheels. What does not have a typical connection structure is adopted, and is configured as shown in FIG.
[0003]
That is, as shown in FIG. 5, the operation speed when the steering handle provided on the vehicle body of the order picking truck is rotated is detected by the operation speed sensor 1 composed of an encoder or the like, and the power steering motor 2 The motor rotation speed is detected by a motor rotation speed sensor 3 composed of an encoder or the like, and the target steering speed is calculated by the calculation by the target steering speed calculation unit 4 from the operation speed of the steering handle detected by the operation speed sensor 1. At this time, since the steering handle operating speed and the target steering speed are in a proportional relationship, the target steering speed can be calculated by multiplying the detected steering handle operating speed by a predetermined constant. .
[0004]
Then, the difference between the target steering speed and the motor rotational speed detected by the motor rotational speed sensor 3 is calculated by the adder / subtractor 5, and this difference is given to the motor driver 6 comprising a chopper circuit or an inverter circuit. Thus, the output of the power steering motor 2 is controlled. Thus, the motor rotation speed by the motor rotation speed sensor 3 is controlled so as to coincide with the target steering speed, and the steering of the steering wheel is controlled according to the rotation operation of the steering handle. At this time, control by the motor driver 6 is performed so that the power steering motor 2 rotates in the operation direction of the steering handle by the operation speed sensor 1.
[0005]
[Problems to be solved by the invention]
However, in the case of an order picking truck, the driver's cab is lifted and lowered, and the steering wheel is arranged at the lower part of the vehicle body so that it is difficult for the operator's eyes to see. In the device, the steering handle has an end and can be rotated indefinitely.For example, when the user tries to run again after picking work while the vehicle is stopped, or when the operator once gets off the vehicle. When boarding again, the operator cannot know which direction the steered wheel is facing.
[0006]
Therefore, conventionally, the vehicle is driven at an extremely low speed and the direction of the steered wheel is confirmed based on the traveling direction. However, since it is necessary to confirm the direction of the steered wheel, the work efficiency is improved. There was a problem of causing a drop. Furthermore, there is a risk of accidentally hitting the vehicle against a wall or the like during such confirmation work, which is not preferable for safety.
[0007]
Such a phenomenon is not limited to an order picking truck, and is a problem that can occur in common in a cargo handling vehicle having a structure in which steering wheels are difficult to see from the outside. In particular, a steering mechanism including a steering handle and steering wheels, etc. This is a significant problem when a mechanical connection structure is not provided between the two.
[0008]
The present invention has been made in view of the above problems, and an object of the present invention is to eliminate the work of confirming the direction of the steered wheels and improve work efficiency.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, the invention according to claim 1 is a cargo handling vehicle having a lifting / lowering means for lifting and lowering a loaded load, and detecting the rotation of a steering handle and based on the detected value. In an electric power steering apparatus for a cargo handling vehicle that controls a power steering motor to steer a steering mechanism, a steering angle detecting means for detecting a steering angle of the steering mechanism and an operator for instructing an operation of the lifting means Operating means for detecting operation to the indicating means, and the steering detected by the steering angle detecting means when an operation to the indicating means is detected by the operation detecting means. And a control means for performing drive control of the power steering motor so that the angle reaches a value corresponding to the straight traveling state of the vehicle.
[0010]
According to this configuration, the steering means detected by the steering angle detection means by the control means when the instruction means is operated by the operator to indicate the operation of the lifting means and this operation is detected by the operation detection means. The drive control of the power steering motor is performed so that reaches a value corresponding to the straight traveling state of the vehicle. Further, when the operator intends to resume the traveling operation, it is not necessary to confirm the direction of the steering wheel again, and the next traveling operation can be started from a state in which the steering wheel is surely directed straight. Therefore, since the work for confirming the direction of the steered wheels as in the prior art is not required, the work efficiency can be improved, and the risk of hitting the vehicle around can be eliminated and the safety can be improved.
[0011]
Further, the invention according to claim 2 is provided with a time measuring means for counting a duration time of the operation to the instruction means, and the control means is provided when the duration time counted by the time measuring means reaches a predetermined time. In addition, the drive control is performed.
[0012]
According to this configuration, if the operation to the instruction means, that is, the operation of the lifting means continues for a predetermined time, it can be determined more reliably that the operator is not performing the traveling operation. There is no problem even if it is steered to face.
[0013]
According to a third aspect of the present invention, when the rotation of the steering handle is detected during the drive control of the power steering motor based on the operation of the instruction unit, the control unit stops the drive control. Then, the control of the power steering motor based on the rotation of the steering handle is started.
[0014]
According to this configuration, when the operator operates the steering handle during automatic steering to a value corresponding to the straight traveling state of the steering angle, drive control of the power steering motor for the automatic steering is stopped. Thus, the operator can always perform the normal control operation, that is, the steering mechanism by controlling the power steering motor based on the detected value of the rotation of the steering handle.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment when the present invention is applied to an order picking truck which is a cargo handling vehicle will be described with reference to FIGS. 1 and 2 are perspective views of the order picking track according to an embodiment of the present invention when viewed from different directions, FIG. 3 is a block diagram of a control system, and FIG. 4 is a flowchart for explaining operations.
[0016]
As shown in FIGS. 1 and 2, the order picking truck 10 according to this embodiment includes a vehicle main body 11, a mast device 12 erected substantially at the center of the vehicle main body 11, and a mast device on which an operator is placed. 12, a cab 13 provided at the rear of the vehicle body 11 so as to be movable up and down, a pair of forks 14 attached to the lower part of the cab 13, and a telescopic lift cylinder 15 for raising and lowering the cab 13. It is comprised by.
[0017]
The driver's cab 13 includes a floor portion 131 on which an operator gets on, a pair of support columns 132 erected on the left and right front end portions of the floor portion 131, and a protective head guard 133 for the operator fixed to the upper ends of both support columns 132. And a U-shaped safety guard 134 whose front end is pivotally supported at a position slightly above the center of both struts 132, and the front end portions of the struts 132 are pivotally supported substantially at the center. And a pair of left and right lateral guards 135.
[0018]
Although not shown in FIGS. 1 and 2, the safety guard 134 is urged upward by springs embedded in both struts 132, and the urging force of the springs causes the rear end of the safety guard 134 to move. The safety guard 134 can be opened simply by lifting up. And in the open state of the safety guard 134, it is set as the state which cannot drive | work and handle for safety ensuring. On the other hand, when the rear end portion of the safety guard 134 is pulled downward against the urging force of the spring, the safety guard 134 is held (locked) in a closed state by a lock mechanism (not shown) so that traveling and cargo handling are possible. Return to the state.
[0019]
By the way, when the safety guard 134 is viewed from the side, the latter half of the safety guard 134 is bent downward, and the lateral beam 134A at the rear end of the safety guard 134 in the closed state is located just at the waist of the operator. Together with the lateral guard 135, the operator is prevented from dropping from the cab 13.
[0020]
As shown in FIG. 1, an operation unit 16 for operating the order picking truck 10 is provided at a substantially central portion of the front surface of the cab 13. The operation unit 16 includes a steering handle 161, a cab. Lift-up button 162A as an instruction means for instructing ascent of 13, lift-stop button 162B as an instruction to stop raising / lowering cab 13, lift-down button as an instruction means for instructing lowering of cab 13 162C, an accelerator lever 163 that can be rotated bidirectionally from a neutral state, a display that displays the state of each part, and the like are disposed. Furthermore, a metal net 17 is attached to the upper half of the cab 13 in order to protect the operator while ensuring a forward view. In FIG. 1, reference numeral 18 denotes a pair of left and right driven wheels disposed at the lower rear end of the floor 131 of the cab 13. Reference numeral 20 denotes a brake pedal. When the operator depresses the brake pedal 20, the brake is released and the vehicle can travel. When the operator depresses the brake pedal, the brake is applied and the vehicle is stopped. Hereinafter, the lift-up button 162A and the lift-down button 162C are also collectively referred to as “lift buttons”.
[0021]
Further, as shown in FIG. 2, in addition to the traveling device 22, the hydraulic device 24, the control device 26, a battery not shown in FIG. 2 is accommodated in the accommodating portion provided at the front portion of the vehicle body 11. Has been. The traveling device 22 includes a traveling motor 221, a speed reduction mechanism 222 including several gears that transmit the rotation of the traveling motor 221, and the rotation of the traveling motor 221 is transmitted via the speed reduction mechanism 222. And a steered wheel 223 to be driven.
[0022]
The hydraulic device 24 includes a hydraulic motor 241, an electromagnetic valve 242, an oil tank 243, and a pump (not shown) driven by the hydraulic motor 241, and a hose connecting the electromagnetic valve 242, the oil tank 243, the pump, and the lift cylinder 15. Connecting members (not shown).
[0023]
When the hydraulic motor 241 drives the pump while hydraulic oil is being supplied from the oil tank 243, pressure oil is generated by the pump. At this time, when the lift-up button 162A is pressed, the electromagnetic valve 242 is opened, pressure oil is supplied to the lift cylinder 15, and the lift cylinder 15 expands. The cab 13 is raised (lifted up) by the extension of the lift cylinder 15. On the other hand, when the lift down button 162C is pressed while the lift cylinder 15 is extended, the solenoid valve 242 is opened, the hydraulic oil is returned from the lift cylinder 15 to the oil tank 243, and the lift cylinder 15 is shortened. By shortening the lift cylinder 15, the cab 13 is lowered (lifted down). Further, when the lift stop button 162B is pressed, the solenoid valve 242 is closed, the hydraulic oil enters and exits the lift cylinder 15, and the expansion / contraction operation of the lift cylinder 15 stops. The lift of the cab 13 is stopped (lift stop) by the stop of the expansion / contraction operation of the lift cylinder 15.
[0024]
The lift cylinder 15 and the hydraulic device 24 that operate in this manner correspond to the lifting means in the present invention.
[0025]
The control device 26 includes a control circuit that controls each unit, and the function thereof will be described later with reference to FIG.
[0026]
The rotation of the power steering motor 32 (see FIG. 3) is transmitted to the steering wheel 223 via a transmission mechanism (not shown in FIG. 2), and the steering wheel 223 is steered. The transmission mechanism and the steering wheel 223 constitute a steering mechanism. At this time, in the order picking truck 10, there is no mechanical connection structure between the steering handle 161 and the steering mechanism, and the steering wheel 223 is steered by an electric power steering device as described below.
[0027]
That is, as shown in FIG. 3, an operation speed sensor 31 including an encoder for detecting an operation speed when the steering handle 161 of the order picking truck 10 is rotated is provided on the vehicle main body 11, and a power steering motor. A steering angle sensor 33 including a potentiometer that detects the steering angle of the steering wheel 223 steered by the steering wheel 223 is provided in the vehicle body 11. The steering angle sensor 33 corresponds to the steering angle detection means in the present invention.
[0028]
Then, the target steering speed calculation unit 34 calculates the target steering speed from the operation speed of the steering handle 161 detected by the operation speed sensor 31. Here, since the operation speed of the steering handle 161 and the target steering speed are in a proportional relationship, the target steering speed can be calculated by multiplying the operation speed detected by the operation speed sensor 31 by a predetermined constant. it can. Further, the relationship between the operation speed of the steering handle 161 and the target steering speed is tabulated in advance and stored in a storage means such as a memory provided in the target steering speed calculation unit 34 and detected by the operation speed sensor 31. The target steering speed corresponding to the operation speed may be read out.
[0029]
Further, the steering angle detected by the steering angle sensor 33 is differentiated by the motor rotation speed calculation unit 35 to calculate the rotation speed of the power steering motor 32. The calculated motor rotation speed and the target steering speed calculation unit are calculated. The difference from the target steering speed calculated by 34 is calculated by the adder / subtractor 36, and this difference is given to the motor driver 37 comprising a chopper circuit or an inverter circuit, and the output of the power steering motor 32 is controlled by the motor driver 37. Thus, the motor rotation speed by the motor rotation speed calculation unit 35 is controlled to coincide with the target steering speed, and the steering of the steering wheel 223 is controlled according to the rotation operation of the steering handle 161. At this time, the rotation direction of the steering handle 161 is also detected by the operation speed sensor 31, and control by the motor driver 37 is performed so that the power steering motor 32 rotates in the detected rotation direction.
[0030]
Here, when the lift button 162A or 162C is pushed by an operator and the switch sensor 41 is turned on by this pushing operation, the continuation time of the on state of the switch sensor 41 from this on time is counted by the timer 42 as a time measuring means. When the continuation time reaches a predetermined time (for example, 5 seconds) set in advance, the target is set so that the steering angle detected by the steering angle sensor 33 reaches a value (for example, 0 °) corresponding to the straight traveling state. Based on the output of the steering speed calculator 34, the motor driver 37 is controlled, and the power steering motor 32 is driven so that the direction of the steered wheels 223 is automatically steered straight.
[0031]
At this time, the continuation time of the ON state of the switch sensor 41 is counted by the timer 42, and when the continuation time reaches 5 seconds (predetermined time), the target steering speed calculation unit 34 sends a predetermined value to the motor driver 37. The output of the automatic steering control signal is started, and this automatic steering control signal is continuously output until the detected steering angle by the steering angle sensor 33 input to the target steering speed calculation unit 34 becomes zero. Based on the direction control signal, the motor driver 37 is driven in a predetermined direction so that the power steering motor 32 has a constant output, and the direction of the steered wheels 223 is steered to a straight traveling state.
[0032]
On the other hand, when the steering wheel 161 is operated during the automatic steering processing operation of the direction of the steering wheel 223 and the output of the operation speed sensor 31 is not zero, the automatic operation of the direction of the steering wheel 223 is immediately performed. The steering process is stopped, and a normal steering state of the steered wheels 223 based on the output of the operation speed sensor 31 is shifted.
[0033]
The target steering speed calculation unit 34 and the motor driver 37 that control the automatic steering process and the automatic steering process are equivalent to the control means in the present invention.
[0034]
Next, the operation will be described with reference to the flowchart of FIG. As shown in FIG. 4, it is determined whether or not the operation speed of the steering handle 161 by the operation speed sensor 31 is 0 (S1). If the determination result is YES, the count value of the timer 42 is 5 seconds ( Whether or not the switch sensor 41 is on is determined by pressing the lift button 162A or 162C (S3). If the determination result is YES, the cab 13 is moved up and down by the hydraulic device 24 or the like, the timer 42 counts up (S4), and the normal operation based on the operation of the steering handle 161 is performed. In order to perform steering, the power steering motor 32 is controlled (S5), and this routine ends.
[0035]
On the other hand, if the determination result in step S2 is YES, it means that the switch sensor 41 has been on for 5 seconds (predetermined time) counted by the timer 42. Therefore, it can be determined that the operator is not performing the traveling operation, and the power steering is performed until the automatic steering process of the steering wheel 223 to the straight traveling state is executed and the detected steering angle by the steering angle sensor 33 becomes zero. The motor 32 is controlled so that the steering wheel 223 is steered straight (S6), and this routine ends.
[0036]
Meanwhile, if the determination result in step S1 is NO or the determination result in step S3 is NO, the count of the timer 42 is cleared (S7), and then the process proceeds to step S5 and is based on the operation of the steering handle 161. Control processing of the power steering motor 32 for performing normal steering is executed.
[0037]
In this way, when the lift button 162A or the lift down button 162C is pushed by the operator and this push operation is detected by the switch sensor 41, the steering angle detected by the steering angle sensor 33 is a value corresponding to the straight traveling state. Thus, the drive control of the power steering motor 32 is performed so that the steering wheel 223 is automatically driven straight.
[0038]
Further, when the traveling is resumed immediately after picking up a load such as a pallet, step S3 becomes NO until step S2 becomes YES, and the count is cleared in step S7, so step S2 becomes YES. Therefore, the steering operation of the steered wheels 223 to the straight traveling state is not performed, so that there is no hindrance to resuming traveling.
[0039]
Therefore, according to the above embodiment, when the operator finishes the raising / lowering operation of the cab 13 and tries to resume the traveling operation, it is not necessary to confirm the direction of the steering wheel 223 again, and the steering wheel 223 is surely connected. The next traveling operation can be started from a state where the vehicle is directed straight ahead, and the conventional operation of confirming the direction of the steering wheel 223 is not required, so that the work efficiency can be improved and the vehicle is Safety can be improved without the risk of hitting.
[0040]
Further, according to the present embodiment, if the steering handle 161 is operated during the automatic steering process of the steering wheel 223 to the straight traveling state, the automatic steering process of the steering wheel 223 to the straight traveling state is canceled and the steering wheel Since the shift to the normal steering state of the steering wheel 223 based on the operation of the handle 161 is made, the operator can easily stop the automatic steering process of the steering wheel 223 to the straight traveling state at any time.
[0041]
In the above embodiment, the case where the present invention is applied to the order picking truck 10 has been described. However, the scope of application of the present invention is not limited to this, and a cargo handling vehicle having a configuration for moving up and down loaded cargo. In particular, the present invention is effective when applied to a vehicle having no mechanical connection structure between the steering handle and the steering mechanism or a cargo handling vehicle in which the direction of the steered wheels is difficult to see from the outside.
[0042]
In the above embodiment, the predetermined time set in advance is set to 5 seconds. However, the predetermined time is not limited to this. For example, the predetermined time is appropriately set according to the time required for picking up a load such as a pallet and immediately restarting traveling. You only have to set it.
[0043]
In the above embodiment, the timer 42 counts the duration time during which the operator lifts and lowers the cab 13 with the lift buttons 162A and 162C. However, the present invention is not limited to this. The drive control may be started immediately when the person detects the state where the operator 13 is being raised or lowered. In this case, since it is not necessary to provide the timer 42, the control configuration can be simplified, and the operator can always start the traveling operation from the straight traveling state after finishing the lifting / lowering operation.
[0044]
Further, in the above-described embodiment, the case where the lift-up button 162A and the lift-down button 162C are arranged on the operation unit 16 has been described. However, the installation positions of these lift buttons 162A and 162C are not limited to this, and the operator Any position on the vehicle may be used as long as it can be operated.
[0045]
In the above-described embodiment, the case where the cab 13 is moved up and down by hydraulic pressure using the hydraulic device 24 or the like as lifting means has been described. However, the present invention is not limited to this, and an electric actuator or the like is used as lifting means. The present invention can also be applied to.
[0046]
In the above embodiment, the instruction means is the lift-up button 162A or the lift-down button 162C. However, the instruction means is not limited to a button, and may be a lever or the like. Anything that can be operated by a person.
[0047]
In the above-described embodiment, the case where the mechanical connection structure is not provided between the steering handle and the steering mechanism has been described. However, the case where the mechanical connection structure is provided between the steering handle and the steering mechanism. The present invention can also be applied to.
[0048]
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.
[0049]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the instruction means is operated by the operator and this operation is detected by the operation detection means, the control means detects the steering angle detection means. Driving control of the power steering motor is performed so that the steering angle reaches a value corresponding to the straight traveling state of the vehicle, so that when an operator tries to resume the traveling operation after the lifting operation of the loaded luggage, It is not necessary to confirm the direction of the steered wheel again, and the next traveling operation can be started from a state in which the steered wheel is directed straight. Therefore, the conventional operation of confirming the direction of the steered wheels is not required, so that the work efficiency can be improved and the safety of the vehicle can be improved by eliminating the possibility of hitting the vehicle to the surroundings.
[0050]
According to the second aspect of the present invention, the duration of the operation to the instruction means is counted, and when this duration reaches a predetermined time, the steering angle is automatically steered to the straight traveling state. Since the drive control is performed, when the operation to the instruction means, that is, the operation of the lifting means continues for a predetermined time, it can be determined more reliably that the operator is not performing the traveling operation, and the result Even if the steering wheel is steered in the straight direction, there is no problem.
[0051]
According to the invention described in claim 3, during the automatic steering process to the value corresponding to the straight traveling state of the steering angle, for example, when the operator operates the steering handle, the power for the automatic steering is Since the drive control of the steering motor is stopped, the operator always performs the normal control operation, that is, the steering mechanism is controlled by the control of the power steering motor based on the detected value of the rotation of the steering handle. Thus, workability can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of an order picking track according to an embodiment of the present invention viewed obliquely from the rear.
FIG. 2 is a perspective view of an order picking track according to an embodiment of the present invention as viewed obliquely from the front.
FIG. 3 is a block diagram of a control system in one embodiment of the present invention.
FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention.
FIG. 5 is a block diagram of a conventional example.
[Explanation of symbols]
10 order picking truck 11 vehicle body 13 cab 15 lift cylinder (lifting means)
24 Hydraulic system (lifting means)
31 Operation speed sensor 32 Power steering motor 33 Steering angle sensor (steering angle detection means)
34 Target steering speed calculation unit (control means)
37 Motor driver (control means)
41 Switch sensor (operation detection means)
42 Timer (time measuring means)
161 Steering handle 162A Lift-up button (instruction means)
162C Lift-down button (instruction means)
223 Steering wheel

Claims (3)

An electric vehicle for a cargo handling vehicle having lifting means for raising and lowering a loaded cargo, the rotation of a steering handle being detected, and a power steering motor being controlled based on the detected value to steer a steering mechanism. In the power steering device,
Steering angle detection means for detecting the steering angle of the steering mechanism;
Instruction means operated by an operator to instruct the operation of the elevating means;
An operation detection means for detecting an operation to the instruction means;
Driving the power steering motor so that the steering angle detected by the steering angle detection means reaches a value corresponding to the straight traveling state of the vehicle when an operation to the instruction means is detected by the operation detection means. An electric power steering apparatus for a cargo handling vehicle, characterized by comprising control means for performing control. Comprising time measuring means for counting the duration of the operation to the instruction means,
2. The electric power steering for a cargo handling vehicle according to claim 1, wherein the control means performs the drive control when the duration time counted by the timing means reaches a predetermined time. apparatus. When the rotation of the steering handle is detected during the drive control of the power steering motor based on the operation of the instruction unit, the control unit stops the drive control, and the control unit based on the rotation of the steering handle 3. The electric power steering apparatus for a cargo handling vehicle according to claim 1, wherein control of the power steering motor is started.

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