JP2003165458A - Motor-driven power steering device for cargo-handling vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve working efficiency by eliminating work for confirming the direction of steering wheel. <P>SOLUTION: When a traveling operation determining section 43 detects a neutral signal from a rotational angle sensor 41, it is determined as an operator having not performed traveling operation and a timer 44 counts the duration of the condition. When the duration reaches a prescribed period, a motor 32 for power steering is controlled by a target steering speed calculating section 34 and a motor driver 37 so that the steering angle detected by a steering angle sensor 33 may reach a value corresponding to a straight movement condition. Thus, the steering wheel is automatically steered so as to obtain the straight movement condition. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus for a cargo handling vehicle having a steering handle and a steering mechanism including steering wheels.

[0002]

2. Description of the Related 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 a steering mechanism including, for example, a steering wheel operated by an operator and steerable steering wheels. A device having no mechanical connection structure between and is adopted, and is configured as shown in FIG.

That is, as shown in FIG. 5, an operation speed sensor 1 including an encoder detects an operation speed when a steering handle provided on a vehicle body of an order picking truck is rotated, and at the same time, for power steering. The motor rotation speed of the motor 2 is detected by the motor rotation speed sensor 3 such as an encoder, and from the operation speed of the steering wheel detected by the operation speed sensor 1,
The target steering speed is calculated by the target steering speed calculation unit 4. At this time, since the operating speed of the steering wheel and the target steering speed are in a proportional relationship, the target steering speed can be calculated by multiplying the detected operating speed of the steering wheel by a predetermined constant. .

Then, the difference between this target steering speed and the motor rotation speed detected by the motor rotation speed sensor 3 is calculated by the adder / subtractor 5, and this difference is given to the motor driver 6 consisting of a chopper circuit or an inverter circuit. The motor driver 6 controls the output of the power steering motor 2. In this way, the motor rotation speed by the motor rotation speed sensor 3 is controlled so as to match the target steering speed, and the steering wheel steering is controlled in accordance with the rotating operation of the steering handle. At this time, the motor driver 6 controls the power steering motor 2 to rotate in the steering wheel operating direction by the operating speed sensor 1.

[0005]

However, in the case of an order picking truck, a driver's cab part on which an operator rides is lifted up and down, and since the steered wheels are arranged at the lower part of the vehicle body, it is particularly visible to the operator's eyes. In addition, since the steering handle of the electric power steering device described above is difficult to rotate without an end, it is difficult to operate, for example, when the user tries to run again after performing picking work while the vehicle is stopped, When getting off the vehicle and boarding again, the operator cannot know which direction the steered wheels are facing.

Therefore, conventionally, the vehicle is run at an extremely low speed and the direction of the steered wheels is confirmed by the traveling direction of the vehicle. However, it is necessary to confirm the direction of the steered wheels. However, there is a problem that the work efficiency is lowered. 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.

Further, such a phenomenon is not limited to the order picking truck, but is a problem that can occur in a cargo-handling vehicle having a structure in which the steered wheels are hard to be seen from the outside, particularly from the steering wheel and the steered wheels. This is a significant problem in the case where there is no mechanical connection structure with the steering mechanism.

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 to improve the work efficiency.

[0009]

In order to achieve the above object, the invention according to claim 1 is a cargo handling vehicle having a traveling device on a vehicle body which operates in response to an operation of traveling operation means by an operator. An electric power steering device for a cargo handling vehicle, comprising rotation detection means for detecting rotation of a steering wheel, and controlling a power steering motor based on a value detected by the rotation detection means to steer a steering mechanism. Steering angle detecting means for detecting the steering angle of the steering mechanism, traveling operation determining means for determining whether or not the traveling operating means is operated, and the traveling operating means is not operated by the traveling operation determining means. The time measuring means for counting the duration of the determined state, and the operation when the duration counted by the time measuring means reaches a predetermined time. Is the steering angle detected is characterized in that a control means for the power drive control of the steering motor to reach a value corresponding to the straight state by the angle detecting means.

According to this structure, when the traveling operation determination means determines that the traveling operation means is not operated, the duration time of the state in which it is determined that the traveling operation means is not operated is measured by the timing means. When the counted time is reached to a predetermined time, the control means controls the drive of 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. In this case, when the traveling operation is not continuously performed for the predetermined time, it can be determined that the worker is performing the work other than the traveling operation, so that the steering angle should reach a value corresponding to the straight traveling state. Controlling does not cause any problems. Further, when the worker intends to restart the traveling operation, it is not necessary to confirm the direction of the steered wheels again, and the next traveling operation can be started from the state in which the steered wheels surely face the straight traveling direction. Therefore, the work for confirming the direction of the steered wheels as in the related art is not required, so that the work efficiency can be improved and the risk of hitting the vehicle around can be eliminated and the safety can be improved.

According to a second aspect of the present invention, the control means controls the rotation of the steering handle by the rotation detecting means during drive control of the power steering motor based on non-operation of the traveling operation means. Is detected, the drive control is stopped, and the control of the power steering motor based on the rotation of the steering wheel is started.

According to this structure, when the operator operates the steering handle during the automatic steering to a value corresponding to the straight traveling state of the steering angle, the drive control of the power steering motor for the automatic steering is performed. Since the control is stopped and the control of the power steering motor based on the detection value of the rotation detection means according to the rotation operation of the steering handle is started, the operator can always perform steering of the normal steering mechanism. Become.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which 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 truck according to the embodiment of the present invention when viewed from different directions, respectively.
Is a block diagram of the control system, and FIG. 4 is a flowchart for explaining the operation.

As shown in FIGS. 1 and 2, the order picking truck 10 in this embodiment is a vehicle body 1
1, a mast device 12 provided upright in the substantially central portion of the vehicle body 11, and a driver's cab 13 provided at the rear portion of the vehicle body 11 so that an operator can be placed on the mast device 12 to move up and down.
And a pair of forks 14 attached to the lower part of the cab 13.

The driver's cab 13 is provided with a floor portion 131 on which an operator rides, a pair of columns 132 standing upright on the left and right front ends of the floor portion 131, and a worker fixed to the upper ends of both columns 132 for protecting the operator. A head guard 133, a safety guard 134 having a U-shape in plan view whose front ends are rotatably supported at positions slightly above the centers of both columns 132, and the front ends of the columns 132 are rotatable at substantially the centers thereof. And a pair of left and right lateral guards 135 supported by.

Although not shown in FIGS. 1 and 2, the safety guard 134 is urged upward by springs embedded in both columns 132, and the urging force of the springs causes the safety guard 134 to move backward. The safety guard 134 can be opened by simply flipping the end up. And the safety guard 134
In the open state, the vehicle is not allowed to travel or load for safety. On the other hand, when the rear end portion of the safety guard 134 is pulled down against the biasing force of the spring, the safety guard 1 is locked by a lock mechanism (not shown).
34 is retained (locked) in the closed state, and returns to a state where traveling and cargo handling are possible.

When the safety guard 134 is viewed from the side, the rear half of the safety guard 134 is bent downward, and the cross beam 1 at the rear end of the safety guard 134 in the closed state.
34A is located exactly on the waist of the worker, and both side guards 135
At the same time, the worker is prevented from falling from the cab 13.

Further, as shown in FIG. 1, an operating portion 16 for operating the order picking truck 10 is provided substantially in the center of the front surface of the cab 13, and the operating portion 16 is provided.
The steering wheel 161, a lift button 162 including a plurality of buttons (for example, three buttons in FIG. 1) for instructing the lifting and lowering of the driver's cab 13, an accelerator lever 163 as a traveling operation means in the present invention, and various parts. A display or the like for displaying the status is provided. Furthermore, the cab 13
A metal net 17 is attached to the upper half portion of the upper part to protect the operator while securing a front view.

The accelerator lever 163 is configured to be bidirectionally rotatable from the neutral position, and is configured to return to the neutral position by an urging member such as a spring when the hand is released in the rotated state. The accelerator lever 163 has a rotation angle sensor 41 including a potentiometer and the like for detecting the rotation direction and the rotation angle of the lever (see FIG. 3).
Is attached.

The brake micro switch 42 is attached to the brake pedal 20 disposed at a proper position in the front part of the floor portion 131.
(See FIG. 3) is installed, and the operator can pedal 2
When 0 is not depressed, the brake micro switch 42 is turned off, the electromagnetic brake is activated, and the steering wheel 22
3 (see FIG. 2) is held in the braking state and the vehicle stops, while when the worker depresses the pedal 20, the brake micro switch 42 is turned on, the braking state is released, and the vehicle is allowed to run. In addition, 18 in FIG. 1 is a cab 13
The left and right driven wheels are arranged at the lower rear end of the floor portion 131.

Further, as shown in FIG. 2, a traveling unit 22, a hydraulic unit 24, a control unit 26, and a battery not shown in FIG. 2 are provided in a housing portion provided at a front portion of the vehicle body 11. Etc. are housed. This traveling device 22
A traveling motor 221, a speed reduction mechanism 222 composed of several gears for transmitting the rotation of the traveling motor 221, and a steering wheel 223 driven by the rotation of the traveling motor 221 being transmitted via the reduction mechanism 222. It has and.

The hydraulic system 24 is provided with a hydraulic motor 241 and a solenoid valve 242, and raises and lowers the cab 13 together with the fork 14. Further, the control device 26 includes a control circuit that controls each unit, and the function thereof will be described later with reference to FIG.

Then, the power steering motor 32
The rotation of (see FIG. 3) is transmitted to the steered wheels 223 via a transmission mechanism (not shown in FIG. 2), and the steered wheels 223 are steered. This transmission mechanism and the steering wheel 22
A steering mechanism is constituted by 3. At this time, in the order picking truck 10, the steering wheel 161
There is no mechanical connection structure between the steering wheel and the steering mechanism, and the steered wheels 223 are steered by the electric power steering device described below.

That is, as shown in FIG. 3, an operation speed sensor 31 composed of an encoder or the like for detecting an operation speed when the steering handle 161 of the order picking truck 10 is rotationally operated is provided in the vehicle body 11, and at the same time, the power is reduced. A steering angle sensor 33 including a potentiometer and the like for detecting the steering angle of the steered wheels 223 steered by the steering motor 32 is provided in the vehicle body 11. Here, the operation speed sensor 31 corresponds to rotation detecting means, and the steering angle sensor 33 corresponds to steering angle detecting means.

Then, the target steering speed calculator 34 calculates the target steering speed from the operation speed of the steering wheel 161 detected by the operation speed sensor 31. here,
Since the operation speed of the steering wheel 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. Further, the relationship between the operation speed of the steering wheel 161 and the target steering speed is made into a table 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.

Further, the steering angle detected by the steering angle sensor 33 is differentiated by the motor rotation speed calculator 35 to calculate the rotation speed of the power steering motor 32, and the calculated motor rotation speed and the target steering angle are calculated. The difference from the target steering speed calculated by the speed calculation unit 34 is calculated by the addition / subtraction unit 36, and this difference is given to the motor driver 37 composed of a chopper circuit or an inverter circuit, and the output of the power steering motor 32 is output by the motor driver 37. Is controlled in this way, the motor rotation speed is controlled by the motor rotation speed calculation unit 35 so as to match the target steering speed, and the steering of the steered wheels 223 is controlled according to the rotating operation of the steering handle 161. At this time, the rotation speed of the steering wheel 161 is also detected by the operation speed sensor 31, and the motor driver 37 is operated so that the power steering motor 32 rotates in the detected rotation direction.
Is controlled by.

The rotation angle sensor 41 attached to the accelerator lever 163 outputs a detection signal (voltage signal in the case of a potentiometer) according to the rotation direction and rotation angle of the accelerator lever 163, and the vehicle travels depending on the rotation direction. The direction (forward / reverse) is determined, and the traveling speed of the vehicle is determined according to the rotation angle. Also, the lever 16
The rotation angle of 3 is a predetermined range from the neutral position (for example, ± 5
When it is within the range of (°), the rotation angle sensor 41 outputs a neutral signal indicating that it is in the neutral state.

Here, when the traveling operation determining section 43 as the traveling operation determining means detects that the neutral signal is not output from the rotation angle sensor 41, it is determined that the operator is performing the traveling operation. It On the other hand, when the traveling operation determination unit 43 detects that the neutral signal is output from the rotation angle sensor 41, it is determined that the operator is not performing the traveling operation.

Then, the duration time of the state in which the traveling operation determination unit 43 determines that the traveling operation is not performed by the worker is counted by the timer 44 as a time measuring means, and the duration time is set to a predetermined time. (For example,
180 seconds), the steering angle detected by the steering angle sensor 33 is a value (eg, 0) corresponding to the straight traveling state.
), The motor driver 37 is controlled based on the output of the target steering speed calculation unit 34, the power steering motor 32 is driven, and the steering wheels 223 are steered to the straight traveling state.

At this time, the duration time when the accelerator lever 163 is in the neutral state is counted by the timer 44, and when this duration time reaches 180 seconds (predetermined time), the target steering speed calculation unit 34 instructs the motor driver 37. Output of a predetermined automatic steering control signal is started, and this automatic steering control signal is continuously output until the steering angle detected by the steering angle sensor 33 input to the target steering speed calculation unit 34 becomes 0, On the basis of this automatic steering control signal, the motor driver 37 drives the power steering motor 32 in a predetermined direction so as to have a constant output.
The direction of 3 is steered straight.

On the other hand, when the steering wheel 161 is operated during the automatic steering processing operation of the steering wheel 223 and the output of the operation speed sensor 31 is not 0, the steering wheel 223 is immediately operated. The automatic steering process for the direction is stopped and the normal steering state of the steered wheels 223 based on the output of the operation speed sensor 31 is set.

The target steering speed calculation unit 34 and the motor driver 37 which control the automatic steering process and the suspension of the automatic steering process correspond to the control means in the present invention.

Next, the operation will be described with reference to the flowchart of FIG. As shown in FIG. 4, it is determined whether the operation speed of the handle 161 by the operation speed sensor 31 is 0 (S1), and if the result of this determination is YES,
It is determined whether or not the driving operation is performed (S
2) If the determination result is YES, the timer 44 starts counting.

Then, the count value of the timer 44 is 180
It is determined whether the time is longer than a second (predetermined time) (S
3) If the result of this determination is NO, the timer 44 counts up (S4), and the power steering motor 3 is operated in order to carry out normal steering based on the operation of the steering wheel 161.
2 is controlled (S5), and this routine ends.

On the other hand, the judgment result of the step S3 is YE.
If it is S, it means that the traveling operation is not performed for 180 seconds (predetermined time) counted by the timer 44, and the worker performs other work other than the traveling operation. It can be determined that the steering wheel 223 is in the straight running state, and the power steering motor 32 is controlled until the steering angle detected by the steering angle sensor 33 becomes zero. Is automatically steered to the straight traveling state (S6), and this routine ends.

By the way, if the decision result in the step S1 is NO or the decision result in the step S2 is NO, the count of the timer 44 is cleared (S7), and thereafter, the process shifts to the step S5 to operate the handle 161. Based on this, control processing of the power steering motor 32 for performing normal steering is executed.

In this way, when the state in which the operator is not performing the traveling operation continues for a predetermined time, the power steering motor 32 is set so that the steering angle detected by the steering angle sensor 33 reaches a value corresponding to the straight traveling state. Drive control is performed, and the steered wheels 223 are automatically steered to a straight traveling state. In this case, when the state where the traveling operation is not performed continues for a predetermined time, it can be determined that the worker is performing other work other than the traveling operation, and therefore the steering angle reaches the value corresponding to the straight traveling state. The motor control does not cause any problems.

Further, when the traveling operation is immediately performed after the traveling operation is not performed for a short time less than the predetermined time in order to perform the operation of scooping a load such as a pallet, the above steps are performed. S3 is YES
Until step S2 becomes NO and step S2
Since the count is cleared in step 7, step S3
Does not result in YES, the automatic steering operation of the steered wheels 223 to the straight traveling state is not performed, so that the restart of the traveling operation is not hindered.

Therefore, according to the above-described embodiment, for example, when the user tries to run again after performing a picking work for a predetermined time or more in a stopped state, or when the worker once gets out of the vehicle and a predetermined time or more elapses and then re-boards. It is not necessary to confirm the direction of the steered wheels 223 again when trying to start traveling, and the next traveling operation can be started from the state in which the steered wheels 223 are surely oriented straight ahead. Since it is unnecessary to confirm the direction of the steered wheels 223, the working efficiency can be improved, and the safety can be improved without the risk of hitting the vehicle around.

Further, according to the above embodiment, the steered wheels 22
3 during the automatic steering process to the straight traveling state, the steering wheel 1
When 61 is operated, the automatic steering process of the steered wheels 223 to the straight traveling state is stopped and the steering wheel 223 is shifted to the normal steered wheel 223 steering state based on the operation of the steering wheel 161. Therefore, it is easy to add a new member. With such a configuration, the operator can easily stop the automatic steering process for moving the steered wheels 223 to the straight traveling state at any time.

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 particularly, the steering handle and the steering mechanism. It is effective when applied to a material handling vehicle that does not have a mechanical connection structure between them or a cargo handling vehicle in which the directions of the steered wheels are difficult to see from the outside.

In the above embodiment, the case where the steering handle and the steering mechanism are not mechanically connected has been described. However, the steering handle and the steering mechanism are mechanically connected. The present invention can be applied to the case where

Further, in the above embodiment, the predetermined time set in advance is set to 180 seconds, but it is not limited to this and may be set to an appropriate value.

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.

[0045]

As described above, according to the first aspect of the invention, when the duration of the state in which the traveling operation is not performed reaches the predetermined time, the control means detects the steering angle detection means. Since the drive control of the power steering motor is performed so that the steering angle to reach the value corresponding to the straight traveling state, it is not necessary to confirm the direction of the steering mechanism again when the operator tries to restart the traveling operation. ,
The next traveling operation can be started from the state in which the steering mechanism faces straight ahead, which eliminates the conventional work of confirming the direction of the steering mechanism, which can improve the work efficiency and the vehicle. It is possible to improve safety without fear of hitting the surroundings.

According to the second aspect of the present invention, if, for example, the operator operates the steering handle during automatic steering to a value corresponding to the straight traveling state of the steering angle, the automatic steering is performed. Since the drive control of the power steering motor is stopped and the control of the power steering motor based on the detection value of the rotation detection means of the steering wheel is started, the operator always operates the steering mechanism of the normal steering mechanism. Can be performed, and the workability can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of an order picking truck according to an embodiment of the present invention as seen obliquely from the rear.

FIG. 2 is a perspective view of the order picking truck according to the embodiment of the present invention as seen obliquely from the front.

FIG. 3 is a block diagram of a control system in an 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 31 Operation speed sensor (rotation detecting means) 32 Power steering motor 33 Steering angle sensor (steering angle detection means) 34 Target Steering Speed Calculation Unit (Control Unit) 37 Motor driver (control means) 41 Rotation angle sensor 43 Travel Operation Determining Section (Run Operation Determining Means) 44 timer (time keeping means) 161 Steering handle 163 Accelerator lever (travel operation means) 223 steering wheel

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B62D 117: 00 B62D 117: 00 F term (reference) 3D032 CC50 DA03 DA09 DA92 DB05 DB11 DB12 DC03 DC09 DC32 DC33 DD18 DE20 EB04 EB08 EC21 GG06 3D033 CA17 CA19 CA21 CA24 3F333 AA02 CA11 DA10 DB10 FA32

Claims (2)

[Claims] 1. A cargo handling vehicle comprising a traveling device, which is operated according to an operation of a traveling operation means by a worker, on a vehicle body,
Equipped with a rotation detecting means for detecting the rotation of the steering wheel,
An electric power steering apparatus for a cargo-handling vehicle, which steers a steering mechanism by controlling a power steering motor based on a value detected by the rotation detecting means, comprising: steering angle detecting means for detecting a steering angle of the steering mechanism; Traveling operation determining means for determining whether or not the operating means is operated, and timing means for counting the duration of the state in which the traveling operation determining means determines that the traveling operation means is not operated, The drive control of the power steering motor is performed so that the steering angle detected by the steering angle detection means reaches a value corresponding to a straight traveling state when the continuation time counted by the timing means reaches a predetermined time. An electric power steering device for a cargo handling vehicle, comprising: 2. The drive control means, when rotation of the steering wheel is detected by the rotation detection means during drive control of the power steering motor based on non-operation of the traveling operation means. The electric power steering apparatus for a cargo handling vehicle according to claim 1, wherein the control of the power steering motor based on the rotation of the steering wheel is started.