JPH0798640B2 - Cargo handling control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling control device for driving and controlling a hydraulic lift cylinder for raising and lowering a cargo handling work member such as a fork in a cargo handling vehicle including a forklift.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind, for example, FIG.
A cargo handling control device applied to an unmanned forklift truck is known as shown in FIG. This cargo handling control device has a fork 2
A hydraulic lift cylinder 22 for raising and lowering 1 is provided. The hydraulic circuit 23 that drives the lift cylinder 22 includes a pump 26 that is driven by a motor 25 to pump the working oil in the tank 24 to the lift cylinder 22, and a control valve 27 that controls the flow of the working oil. It is provided. The lift cylinder 22 has
A lift sensor 28 is provided to detect a lift operating position H corresponding to the lift height (lifting height) of the fork 21.
Further, the cargo handling control device is provided with a microcomputer 29 that stores a predetermined control program, and the detection signal of the lift sensor 28 is input to the microcomputer 29. Furthermore, microcomputer 2
9 drives and controls the control valve 27 on the basis of the detection signal, and the motor 2 via the power controller 30.
5 is driven and controlled.

When the microcomputer 29 raises the lift cylinder 22 to raise the fork 21,
The control valve 27 is opened according to a preset command value, and the motor 25 is rotated at a constant speed according to the preset command value. At this time, the microcomputer 29 determines that the lift sensor 2
The lift operating position H of the lift cylinder 22 is determined based on the detection signal of 8. In addition, as shown in FIG.
9 is the deceleration position H at which the ascending operating position H should start deceleration
When it is determined that the lift cylinder 22 has reached 1, the control valve 27 and the motor 25
Gradually lower each command value to the set level. Thereafter, when the microcomputer 29 determines that the lift operating position H of the lift cylinder 22 has reached a predetermined stop position H2, it issues a command to close the control valve 27 and stop the rotation of the motor 25.

[0004]

However, in the above-mentioned prior art, when the fork 21 is raised, in order to raise the lift cylinder 22, the control valve 27 and the motor 25 are uniformly distributed according to a preset control program. It was just drive control. Further, as shown in FIG. 5, since the ascending operating speed V of the lift cylinder 22 varies depending on the presence or absence of the load applied to the fork 21 or the magnitude thereof, the acceleration force and the deceleration force also vary depending on the magnitude of the load. Therefore, due to the difference in load, the lift cylinder 2
There is a possibility that variation E may occur in the second stop position and, as a result, the actual load height may deviate from the target stop position H2.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to perform cargo handling control capable of always matching an actual load-carrying height with a target stop position regardless of the magnitude of the load. To provide a device.

[0006]

In order to achieve the above object, in the present invention, a hydraulic lift cylinder for raising and lowering a work member for cargo handling, a hydraulic drive means for driving the lift cylinder, and a lift cylinder. A position detection means for detecting the operating position of the, and a cargo handling control device for driving and controlling the hydraulic drive means to control the operation of the lift cylinder based on the detection result of the position detection means,
Speed detection means for detecting the rising operation speed of the lift cylinder, speed comparison means for comparing the detection speed of the speed detection means with a preset reference speed, and speed comparison thereof
Based on the comparison result of the means, the detected speed is higher than the reference speed
If it is larger, lift it up before stopping the lift cylinder.
Command value to the hydraulic drive means to increase the deceleration force
If the determined speed is lower than the reference speed, the riff
The deceleration force before stopping
Command value determining means for determining the command value to the hydraulic drive means, and pre-stop control means for controlling the drive of the hydraulic drive means before the lifting operation of the lift cylinder is stopped based on the determination result of the command value determining means. It has and.

[0007]

According to the above construction, the speed detecting means detects the lifting operation speed of the lift cylinder when the lift cylinder is being lifted by the hydraulic drive means. And speed
The comparison means compares the detection result of the speed detection means with a preset reference speed . The command value determining means is the speed comparing means.
Detection speed is higher than the reference speed based on the comparison result
In some cases, deceleration before the lift cylinder stops operating
Determines the command value to the hydraulic drive so that the force becomes large
However, if the detected speed is lower than the reference speed, the lift
The deceleration force before the Linda rises and stops is reduced.
Thus , the command value for the hydraulic drive means is determined. Then, the pre-stop control means controls the drive of the hydraulic drive means before the lifting operation of the lift cylinder is stopped based on the determination result of the command value determination means.

Therefore, when the load applied to the lift cylinder via the work member for cargo handling is large, the lifting operation is not stopped.
If the deceleration force of is relatively small and the load is small,
The deceleration force before the ascending operation is stopped can be made relatively large.
It As a result, the lifting operation of the lift cylinder is stopped so as to match the target stop position.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a cargo handling control device for an unmanned forklift will be described in detail with reference to FIGS. FIG. 1 is a schematic configuration diagram showing a cargo handling control device in this embodiment. This cargo handling control device is provided with a hydraulic lift cylinder 2 that lifts and lowers a fork 1 as a working member for cargo handling. A hydraulic circuit 3 for driving the lift cylinder 2 is provided with a motor 4 as a hydraulic drive means, a pump 7 and a control valve 5. The motor 4 drives the pump 7 to pump the working oil in the tank 6 to the lift cylinder 2, and the control valve 5
Controls the flow of its working oil. Lift cylinder 2
The lift sensor 8 is provided with a pulse encoder as a position detecting means and a speed detecting means for detecting an ascending operating position H corresponding to the ascending / descending height (lifting height) of the fork 1. Further, this cargo handling control device is provided with a microcomputer 9 which constitutes a speed comparison means for storing a predetermined control program for operating an unmanned forklift , a command value determination means and a pre-stop control means. A pulse signal PS is input from the lift sensor 8. Further, the microcomputer 9 determines the ascending operation speed V and the ascending operation position H of the lift cylinder 2 on the basis of the pulse signal PS, and the control valve 5 according to the result of the operation.
And the drive control of the motor 4 via the power controller 10.

Next, the operation of the cargo handling control device configured as described above will be described with reference to the flow chart of FIG. 2 and the graph of FIG. FIG. 2 is a flow chart illustrating a routine for load control executed by the microcomputer 9. When the processing shifts to this routine, first, at step 101, a loading instruction for raising the fork 1 is awaited,
Upon receiving the load instruction, the process proceeds to the next step 102.

In step 102, a fork rising acceleration process is executed. That is, in order to gradually open the control valve 5, the valve current value VI to the valve 5 is gradually increased, and at the same time, the rotation of the motor 4 is gradually increased to pump the pump 7.
The duty command value DS to the power controller 10 is gradually increased in order to drive the. That is, the process of pumping the working oil to the lift cylinder 2 to accelerate the fork 1 is executed.

Next, at step 103, the fork 1 is moved by a predetermined amount (in this embodiment, "100 m
m ”) to raise the lift cylinder 2 to the operating position H
Waits until the initial position H0 is reached, and when the initial position H0 is reached, the process proceeds to step 104. The determination in step 103 is made by determining the ascending operating position H based on the pulse signal PS of the lift sensor 8. During this period, the lifting operation speed V of the lift cylinder 2 gradually increases.

Then, in step 104, the valve current value VI to the control valve 5 is increased to the maximum value VImax in order to raise the lift cylinder 2 at the maximum target speed Vmax0.
And the duty command value DS for the motor 4
Is controlled to the maximum value DSmax. That is, the maximum target speed V
The lifting operation of the lift cylinder 2 is controlled so that it becomes max0.

Then, in step 105, counting of the pulse signal PS of the lift sensor 8 is started. That is,
Based on the pulse signal PS, the pulse signal PS is fetched at regular intervals in order to calculate the ascending operation speed V of the lift cylinder 2 and thus the ascending speed of the fork 1. or,
Based on the pulse signal PS, the pulse signal PS is fetched at regular intervals in order to calculate the lift operating position H of the lift cylinder 2 and thus the lift position of the fork 1.

Then, in step 106, the ascending operation speed V and the ascending operation position H are calculated based on the fetched pulse signal PS. Then, in step 107, it waits for the ascending operating position H to reach the decelerating position H1 at which deceleration is to be started.

In step 108, the actual ascending operation speed V of the lift cylinder 2 is compared with a predetermined reference speed V0 to determine the speed difference. Here, when the ascending operation speed V is higher than the reference speed V0, it means that the load applied to the lift cylinder 2 is small. Conversely, the fact that the ascending operation speed V is lower than the reference speed V0 means that the load applied to the lift cylinder 2 is large. In this embodiment, the reference speed V0 corresponds to the maximum target speed Vmax0 while the valve current value VI and the duty command value DS are controlled to the maximum values VImax and DSmax. Therefore, this step 1
At 08, the valve current value VI and the duty command value DS
The maximum actual speed Vmax1 and the maximum target speed Vmax0 are compared while the values are controlled to the maximum values VImax and DSmax.

Then, in step 108, if the ascending operating speed V (maximum actual speed Vmax1) is smaller than the reference speed V0 (maximum target speed Vmax0), that is, if the load applied to the lift cylinder 2 is large, in step 109, A value obtained by adding the predetermined value α to the valve reference current value VI0 is set as the pre-stop current value VI1, and a value obtained by adding the predetermined value α to the duty reference command value DS0 is also set as the pre-stop command value DS1. Also, step 10
If the ascending operating speed V (maximum actual speed Vmax1) is greater than the reference speed V0 (maximum target speed Vmax0) at 8, that is, if the load applied to the lift cylinder 2 is small, at step 110, the valve reference current value VI
A value obtained by subtracting the predetermined value α from 0 is set as the pre-stop current value VI1, and a value obtained by subtracting the predetermined value α from the duty reference command value DS0 is also set as the pre-stop command value DS1. Further, in step 108, if the rising actuation speed V is equal to the reference speed V0 , step 1
11, the valve reference current value VI0 is set as the pre-stop current value VI1 and the duty reference command value D
Similarly, S0 is set as the pre-stop command value DS1.

After that, the process proceeds from each of steps 109 to 111, and in step 112, the valve current value VI to the control valve 5 is controlled to become the pre-stop current value VI1 in order to gradually narrow the valve. At the same time, the duty command value DS to the power controller 10 is controlled to be the pre-stop command value DS1 in order to decelerate the rotation of the motor 4 and decelerate the pump 7. As a result, the supply of hydraulic oil to the lift cylinder 2 is gradually reduced, and the rising operating speed V is gradually reduced.

Next, at step 113, the target stop position at which the lift cylinder 2 is to be stopped while the valve current value VI and the duty command value DS are maintained at the pre-stop current value VI1 and the pre-stop command value DS1, respectively. It waits until it reaches H2, and when it reaches the target stop position H2, it proceeds to step 114. Then, in the last step 114, the pre-stop current value VI1 and the pre-stop command value DS1 are each controlled to "0" to shut off the supply of hydraulic oil to the lift cylinder 2 to bring the lift cylinder 2 to the target stop position H2. Stop. That is, the fork 1 is stopped at the target loading position.

As described above, according to the cargo handling control apparatus of this embodiment, the actual ascending operating speed V of the lift cylinder 2 is compared with the reference speed V0, and the difference in speed difference is applied to the lift cylinder 2. The difference is the pre-stop current value VI1
And the pre-stop command value DS1 is appropriately determined. Then, the control valve 5 and the motor 4 are drive-controlled based on the determined pre-stop current value VI1 and pre-stop command value DS1, and the operation of the lift cylinder 2 before deceleration operation stop is decelerated. That is, the deceleration force before the lifting operation of the cylinder 2 is stopped is controlled according to the difference in the load applied to the lift cylinder 2.

Therefore, even when the load acting on the lift cylinder 2 via the fork 1 changes with each cargo handling operation, the deceleration force before the lifting operation of the lift cylinder 2 is stopped is adjusted according to the magnitude of the load. You can That is, when the load is large, the deceleration force can be made relatively small accordingly, and when the load is small, the deceleration force can be made relatively large accordingly.
As a result, the lifting operation of the lift cylinder 2 can always be stopped in the vicinity of the target stop position H2, it is possible to prevent the stop position from being varied, and a position where the load position by the fork 1 is targeted. Can be matched to.

The present invention is not limited to the above-mentioned embodiments, and a part of the structure can be appropriately modified and carried out without departing from the spirit of the invention. (1) In the above embodiment, the cargo handling control device is embodied as an unmanned forklift, but it may be embodied as a manned forklift that is driven and operated by a person, or as a cargo handling vehicle other than a forklift. Further, as long as it is provided with a hydraulic lift cylinder for raising and lowering a work member for cargo handling, it can be embodied as a cargo handling mechanism that only performs cargo handling.

(2) In the above embodiment, the position detecting means and the speed detecting means are constituted by one lift sensor 8, but the position detecting means and the speed detecting means may be constituted by separate sensors.

[0024]

As described above in detail, according to the present invention,
The excellent effect that the actual load height due to the lifting operation of the lift cylinder can be always matched with the target stop position regardless of the magnitude of the load.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a cargo handling control device for an unmanned forklift according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the cargo handling control device according to the embodiment.

FIG. 3 is a graph illustrating the relationship between the lift operating position and lift operating speed of the lift cylinder, the duty command value of the motor, and the valve current value of the control valve, illustrating the operation of the cargo handling control device according to the embodiment.

FIG. 4 is a schematic configuration diagram showing a cargo handling control device in a conventional example.

FIG. 5 is a graph for explaining the relationship between the lift operating position of the lift cylinder and its lift operating speed in the conventional example.

[Explanation of reference numerals] 1 ... Fork as a working member, 2 ... Lift cylinder,
4, 5, 7 ... Motor and control valve forming hydraulic drive means
A pump and a pump, 8 ... Position detecting means and speed detecting means
Lifting height sensor, 9 ... Speed comparison means, command value determination means
And a microcomputer that constitutes pre-stop control means.

Claims (1)

[Claims] 1. A hydraulic lift cylinder for raising and lowering a work member for cargo handling, a hydraulic drive means for driving the lift cylinder, and position detection means for detecting an operating position of the lift cylinder. In a cargo handling control device for driving and controlling the hydraulic drive means to control the operation of the lift cylinder based on the detection result of the detection means, a speed detection means for detecting a rising operation speed of the lift cylinder, and the speed detection means. Based on the comparison result of the speed comparison means and the speed comparison means for comparing the detected speed with the preset reference speed,
Lifting of the lift cylinder when it is greater than the sub speed
In order to increase the deceleration force before stopping the operation,
Determine the command value to the driving means, and detect speed from the reference speed
If it is also smaller, before the lift cylinder stops moving up
To the hydraulic drive means so that the deceleration force at
And a pre-stop control means for controlling the drive of the hydraulic drive means before the lifting operation of the lift cylinder is stopped based on the determination result of the command value determination means. Control device.