JPH03293300A - Device for automatic control of clamping article in industrial vehicle - Google Patents

Abstract

PURPOSE:To compose an automatic control device, which can clamp articles, and tighten the clamping force and, in addition, avoid excessive clamping force in order to prevent breakage of the articles, by increasing arm gripping force up to a required value by means of an actuator when detected gripping pressure of arms is less by a certain amount or more than the set value necessary for clamping the articles. CONSTITUTION:Actual gripping pressure B is compared with optimum gripping pressure A by means of a controller 24 during operation of a change-over valve 6 and a change- over valve 19 for a pilot valve. When the actual gripping pressure B is larger than the optimum gripping pressure A, operation of the change-over valves 6 and 19 is stopped. After the operation of the change-over valve 19 is stopped, the controller 24 compares the actual gripping pressure B with the optimum gripping pressure A. When the actual gripping pressure B is less by a required allowable amount or more than the optimum gripping pressure A, a cylinder 20 contracts again by operating the change-over valve 19. Thus, the controller 24 always executes a lever operating program and controls a hydraulic system so that clamping arms 21 grip an article L with the optimum gripping pressure A set by means of a pressure setting trimmer 26 according to signals sent from a safety switch 28 and an operating position sensor 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an automatic clamp control device for an industrial vehicle.

[Prior Art] Generally, a clamp device is used as an attachment for transporting a cylindrical load such as a roll of paper in a forklift. This clamp device includes a movable and a fixed clamp arm, and a hydraulic cylinder is expanded and contracted by operating a clamp lever, and the movable clamp arm is opened and closed. Then, the movable arm is moved in the closing direction, the roll paper between the movable arm and the fixed arm is gripped by the movable arm, and the roll paper is conveyed as the vehicle travels.

[Problems to be Solved by the Invention] The gripping force of the above-mentioned movable arm may loosen during transportation due to leakage of the hydraulic cylinder, etc., and the arm must be closed by operating the clamp lever at predetermined time intervals. The operator moves the arm in the direction to increase the gripping force, or the operator operates the lever based on experience and tightens the arm to compensate for the loosened force, ensuring stable conveyance of the roll paper. .

In the above-mentioned apparatus, the clamp lever is operated and the clamp control is performed after the arm grips the load, and the steps up to that point must be performed manually.

Furthermore, if the worker operates the clamp lever excessively,
The clamp arm applies strong pressure to the load, potentially damaging it.

The purpose of this invention is to solve the above-mentioned problems, and the purpose is to eliminate the complexity of manual operations and avoid clamping operations, retightening operations, and even excessive clamping operations that may damage the load. An object of the present invention is to provide an automatic clamp control device in an industrial vehicle that does not have any problems.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the present invention drives an actuator by operating a cargo handling lever when picking up cargo,
In an industrial vehicle that grips a load by moving at least one of a pair of clamp arms facing each other in the closing direction, an automatic control device that is operated when the cargo handling lever is not operated and instructs the clamp arm to automatically move in the closing direction. a movement instruction means, a detection means for detecting the gripping pressure of the load by the clamp arm when the clamp arm grips the load, the gripping pressure of the arm detected by the detection means, and a preset necessary value for the load. a comparison determination means for determining this when the gripping pressure of the arm is lower than a predetermined allowable amount from the required value for picking up the load; and based on the determination result of the comparison determination means, the actuator is driven to clamp the load. The gist thereof is to provide a driving means for increasing the gripping force of the arm to a value necessary for picking up the load.

[Operation] When the cargo handling lever is not operated, the automatic movement instructing means is operated to instruct the clamp arm to automatically move in the closing direction. When the detection means detects the gripping pressure of the clamp arm, the comparison and determination means compares the gripping pressure of the arm detected by the detection means with a preset value required for picking up a load, and determines whether the gripping pressure of the arm is This is determined when the value falls below the required value by more than a predetermined allowable amount. The driving means drives the actuator to increase the gripping force of the clamp arm to a value necessary for picking up the load, based on the determination result of the comparison and determination means.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 3.

In FIG. 1, a motor M rotated by an engine drives a hydraulic pump 1, which discharges pressurized oil from an oil tank 2 into a main pipe 3. A diversion valve 4 is disposed in the main pipe 3 and divides the flow of pressure oil between the downstream side of the main pipe 3 and the cargo handling pipe 5. An electromagnetically controlled switching valve 6 is disposed on the downstream side of the main pipe 3, and when the switching valve 6 is in the closed position, the pressure oil discharged by the pump 1 is transferred from the upstream side of the main pipe 3 to the cargo handling pipe 5. flows, increasing the pressure inside the cargo handling pipe 5.

A clamp control valve 7 is provided in the cargo handling pipe 5, and its valve chamber 8 and pressure chamber 9 communicate with each other via a communication port 11 in a partition wall 10. The spool 1 disposed within the valve chamber 8
The lot 13 passes through the communication port 11 from the inner end surface of the pressure chamber 9.
protrudes inward.

In the pressure chamber 9, a large-diameter piston 14 is formed on the outer circumference of the rod 13, and its outer circumferential surface slides against the inner circumferential wall of the pressure chamber 9, so that the pressure chamber 9 is connected to the left chamber 9a and the right chamber 9b. It is divided into two parts.

The spool 12 can be switched to three positions a, b, and c, and there is a gap between the outer end surface of the spool 12 and the inner wall of the valve chamber 8, and between the outer end of the rod 13 and the inner wall of the pressure chamber 9. Compression springs 15 and 1.6 are installed between the spool 12 and the spool 12, respectively, to keep it at the home position (
b position) is held.

Furthermore, a pilot line 17 is connected between the diverter valve 4 and the switching valve 6 of the main line 3, and the pilot line 17 is connected to the left chamber 9a and right chamber 9b of the pressure chamber 9, respectively. It is connected to an electromagnetically controlled pilot switching valve 1.8.19 which serves as the left and right closing drive means. As these switching valves 6 are closed, the pressure inside the main pipe 3 is increased, and the pilot fluid generated in the pilot pipe 17 is transferred to the switching valves 18, 1.
According to the opening/closing of the pressure chamber 9, the air selectively flows through the left chamber 9a and the right chamber 9b of the pressure chamber J 9, increasing the internal pressure of either chamber. As a result, the spool 12 is connected to the compression spring 15 via the piston 14.
．． It is switched to the a and C positions against a force of 16.

A clamp cylinder 20 as an actuator is disposed downstream of the spool 12, and the spool 12 connects the piston chamber 20a of the clamp cylinder 20 to the pump 1 and the bottom 20b to the tank 2 in three positions, thereby contracting the cylinder 20.

When the spool 12 is in the 5 position, the clamp cylinder 20
The piston chamber 20a and bottom chamber 20b are isolated from both the pump 1 and the drain side, and the cylinder 20 is held non-expandable. In addition, the spool 12 is in the C position, and the bottom chamber 20b of the clamp cylinder 20 is connected to the pump 1.
Next, the piston chamber 20a is communicated with the tank 2 to extend the cylinder 20.

A movable clamp lever 21 is connected to the clamp cylinder 20, and when the cylinder 20 is extended, it moves in the opening direction to release the load, and when it contracts, it moves in the contraction direction to grip the load. When the cylinder 20 is held in a non-extendable manner, the arm 21 is held at the current position.

Next, the electrical configuration of this embodiment will be explained.

The operation position sensor 22 is composed of a limit switch, and detects the three positions of the clamp lever 23 operated to operate the clamp arm 21: closed, neutral, or open, and compares and compares this detection signal with the controller as a driving means. Output to 24. The seat sensor 25 is connected to the arm 21
The arm 21 detects that the arm 21 has gripped a load, and outputs this detection signal to the controller 24. The pressure setting trimmer 26 is composed of a variable resistor, and sets the load gripping pressure (optimal gripping pressure A) by the arm 21 inputted by the operator by manual operation of the rotary switch before starting the load picking operation. A signal based on the controller 24
Output to. A pressure sensor 27 serving as a detection means detects the oil pressure value in the clamp cylinder 20, that is, the load gripping pressure (actual gripping pressure B) by the arm 21, and outputs this detection signal to the controller 24.

The operation safety switch 28 and the automatic clamp switch 29 are push-button switches provided on the operating portion 23a of the clamp lever 23 (Fig. 2), and the safety switch 28 outputs an invalidation command signal to the controller 24 when not operated. . Further, when the clamp lever 23 is in the neutral position, the automatic clamp switch 29 as an automatic clamp instruction means outputs an automatic clamp start command signal to the controller 24 based on the pressing operation, and outputs an automatic clamp release command when the clamp lever 23 is pressed again. Output to the controller 24.

The controller 24 disables the signal from the clamp lever 23 in accordance with the disable command signal from the safety switch 28. When the safety switch 28 is operated, the controller 24 determines whether the clamp lever 23 is in the closed, neutral, or open operation position according to the signal from the operation position sensor 22, and according to the result of this determination, the switching valve 6 And the pilot switching valves 18 and 19 are controlled to open and close the arm 21.

The controller 24 drives the switching valve 6 to close the arm 21 to the closed position. Then, when the lever 23 is in the open operation position, the controller 24 drives the pilot switching valve 18 at a predetermined duty ratio to open it, and keeps the pilot switching valve 19 closed,
Introducing pilot fluid into the right chamber 9a of the pressure chamber 9 from the pilot pipe 17 via the switching valve 18 and increasing the pressure of the pilot fluid,
Switch the spool 12 of the control valve 7 to the 3rd position. Also, the controller 24 closes the arm 21,
The pilot switching valve 19 is opened and the pilot switching valve 8 is kept closed, and the pilot fluid from the pilot pipe 17 is introduced into the left chamber 9b of the pressure chamber 9 to increase its pressure. As a result, the spool I2 is extended and the spool 12 of the control valve 7 is switched to the C position. In order to hold the arm 21 unable to open or close, the controller 24 switches the left and right chambers 9a, 9 of the pressure chamber 9 without outputting signals to the switching valve 6 and both pilot switching valves 18, 19.
The pressure inside b is made equal, and the spool 12 is held at position b by the force of both springs 15 and 16.

Based on the signal from the sheet sensor 25, the controller 24 determines that the clamp arm 21 has gripped the load. The controller 24 calculates the actual gripping pressure B of the clamp arm 21 at any given time according to the signal from the pressure sensor 27. The controller 24 calculates the optimal gripping pressure A for the clamp arm 21 to grip the load according to the signal from the gripping pressure setting trimmer 26.

1 The controller 24 includes the switching valve 6 and the pilot switching valve 1
9, the optimum gripping pressure A and the actual gripping pressure B are compared, and when the actual gripping pressure B becomes larger than the optimum gripping pressure A, the driving of the switching valves 6 and 19 is stopped. Further, after the switching valve 19 is stopped, the controller 24 compares the optimum gripping pressure A and the actual gripping pressure B, and if the actual gripping pressure B is lower than the optimum gripping pressure A by a predetermined tolerance α or more, the switching valve 19 is driven to contract the cylinder 20 again.

The controller 24 always executes the lever operation program, and the clamp arm 21 is set to the pressure setting trimmer 26 according to signals from the safety switch 28 and the operation position sensor 22.
The hydraulic system is controlled to grip the load at the optimum gripping pressure A set by the operator.

When the clamp lever 23 is in the neutral position, the controller 24 executes an automatic control program based on the automatic clamp start command signal from the automatic clamp switch 29, and clamps at the optimum gripping pressure A set by the pressure setting trimmer 26. Automatic control is performed with a predetermined sampling time (20 milliseconds in this embodiment) as one control cycle so that the arm 21 grips the load.

Now, the operation of the clamp control device configured as described above will be explained below according to the flowchart shown in FIG.

Now, the vehicle is stopped at a predetermined loading position to pick up cargo. Then, when the optimum gripping pressure A is set by the gripping pressure setting trimmer 26 in step 1, the controller 24 confirms in step 2 that the clamp lever 23 is in the neutral position, and proceeds to step 3. When the automatic clamp switch 29 is pressed down in step 3, the controller 24 drives the switching valve 6 and pilot switching valve 19 in step 4 to contract the cylinder 20 and move the clamp arm 21 in the closing direction.

Next, in step 5, when the actual gripping pressure B is input from the pressure sensor 27, the controller 24 performs step 6.
At that time, the actual gripping pressure B and the optimum gripping pressure B are compared, and if B=A, it is determined that the arm 21 has reliably gripped the load with a pressure that does not cause it to fall. Then, in step 7, the driving of the switching valve 6 and the switching valve 19 is stopped to stop the clamping operation, and the clamp arm 21 is held so that it cannot be opened or closed.

After this, after waiting for 20m5ec in step 8,
In step 9, the controller 24 controls the optimum gripping pressure A-
Determine whether the value of the actual gripping pressure B is greater than or equal to the allowable value
If B≧α, the cylinder 20 is damaged due to a leak in the hydraulic system, etc.
, that is, the actual gripping pressure B of the arm 21 is the allowable value α
It is determined that the amount has decreased by the above amount, and in order to compensate for this decrease, the process returns to step 4, and the clamp arm 21 is caused to perform the clamping operation again.

If AB<α in step 9, the clamp arm 21 returns to step 1 since it is holding the load with sufficient gripping pressure.

If the signal from the pressure sensor 27 is not input in step 5, the preset time t is determined in step 10.
Waiting for the passage of time, it is determined in step 11 whether or not there is an output signal from the sheet sensor 25. When the signal from the sheet sensor 25 is input manually, the process returns to step 4 to continue the clamping operation, and when the signal from the sheet sensor 25 is not input,
It is determined that the operator has erroneously operated the switch 29 even though there is no load, and separate processing is performed.

Further, when the lever 23 is being operated to open or close in step 2, and when the automatic clamp switch 29 is not operated in step 3, the controller 24 executes a manual operation program.

As described above, in this embodiment, when the automatic clamp switch 29 is operated, the clamp arm 21 automatically moves in the closing direction, starts the clamping operation, and grips the load.

Then, when the actual gripping pressure B becomes equal to the optimum gripping pressure A preset in anticipation of preventing damage to the load (1), the clamp arm 21 stops the clamping operation, thereby preventing damage to the load.

If the clamp arm 21 continues to grip the load, the actual gripping pressure B of the arm 21 will decrease due to leakage of the hydraulic system. Therefore, the controller 24 again operates the switching valve 6 and the pilot switching valve 18.
, 1.9 to make the actual gripping pressure B equal to the optimum gripping pressure A. By repeating this operation, the arm 21
retightening is always possible, and the load is prevented from falling from the arm 21.

Note that the present invention is not limited to the above-described embodiments; for example, a hydraulic clamp cylinder 20 may be used as the actuator.
This electric cylinder 20 adopts an electric cylinder instead of
(2) As shown in FIG. 4, pressure chambers 30a and 30b are formed on both sides of the valve chamber 8 and communicate with the same valve chamber 8, and the pressure inside these chambers is Of course, arbitrary changes are possible without departing from the spirit of the invention, such as a configuration in which the spool 12 in the valve chamber 8 is switched by controlling the pilot switching valves 31a and 31b.

6 [Effects of the Invention] As detailed above, the present invention provides an excellent replacement that eliminates the complexity of manual operations and avoids clamping operations, retightening operations, and damage to loads. do.

[Brief explanation of drawings]

FIG. 1 is a hydraulic and electrical circuit diagram showing a clamp control device embodying the present invention, FIG. 2 is a perspective view showing a clamp lever having two switches, and FIG. 3 is a flow chart showing the operation of the controller. FIG. 4 is a hydraulic circuit diagram showing a separate control valve. A pilot switching valve 18.19 as an actuator, a clamp cylinder 20 as an actuator, a clamp arm 21, a clamp lever 23 as a cargo handling lever, a teno controller 24 as a comparison/discrimination means and a driving means, a detection means and a pressure sensor 27. Automatic clamp switch as automatic movement instruction means 29°

Claims (1)

[Scope of Claims] 1. In an industrial vehicle that grips a load by driving an actuator by operating a load handling lever and moving at least one of a pair of mutually opposing clamp arms in a closing direction when picking up a load, automatic movement instructing means that is operated when the cargo handling lever is not operated and instructs the clamp arm to automatically move in the closing direction; and a detection device that detects the pressure in which the clamp arm grips the load when the clamp arm grips the load. comparing the gripping pressure of the arm detected by the detection means with a preset necessary value for picking up the load, and determining when the gripping pressure of the arm falls below the required value for picking up by more than a predetermined allowable amount; An automatic clamp control device for an industrial vehicle, comprising: a comparison/discrimination means that performs a comparison and discrimination; and a drive means that drives an actuator to increase the gripping force of the clamp arm to a value necessary for picking up a load based on the discrimination result of the comparison and discrimination means. .