JPH10182100A - Electric control method for air type cargo carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the change of the weight of a cargo having excellent elevation characteristics by a method wherein a cylinder is driven by an electric signal proportioning a weight signal from a load sensor and an elevation control force is exerted between the load sensor and an actuator. SOLUTION: A signal obtained from a load sensor 13 generates the output of a cylinder 11, brought into a state to be balanced with a control force, through an amplifier 16e and an electric and pneumatic converter 16b. When a control force is continuously applied by an operator, the force of a cargo 15 applied on a floor is decreased and when weight W and the output of the cylinder 11 coincide with each other, the cargo is floated in air. When a control force is exerted on a grip part 12b by an operator to elevate a cargo, the output of the cylinder 11 always proportioning a signal from the load sensor 13 is generated and an arm mechanism is elevated. On landing of the cargo, an output from the cylinder 11 is decreased by an amount equivalent to the control force of an operator and by applying the weight W on the floor, the cargo is brought into a landing state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic cargo handling machine having a lifting mechanism of a parallelogram link type or a jib type and moving cargo using an actuator such as a cylinder.

[0002]

2. Description of the Related Art Conventionally, as a method of controlling a cargo handling machine for lifting and lowering cargo, a balance control method using a load sensor in electric control, a balance control method and a flow control method in air control, and The balance / flow control method was common.

[0003]

Here, the contents and disadvantages of the conventional control method described above will be described.
In the balance control method by electric control using a load sensor, the load is first lifted completely in the air by speed control or flow rate control, and after the accurate weight of the load is detected,
This is stored as a reference signal for the balance control method. Next, the balance control is switched, and the difference between the weight signal newly output from the load sensor and the previously stored reference signal is obtained, and the difference is used as a command signal for raising and lowering, and the control method of the cargo handling machine is used as the command signal. Since the control is shifted from speed control or flow rate control to balance control, the control method is switched externally, which complicates the operation. Had become. In addition, the direction of the operation force applied to raise and lower the cargo by the person is opposite to the direction of the weight change due to the acceleration received during the lifting and lowering of the cargo. There was a problem that it was not possible.

[0004] The problem with air control is as follows. First, the balance control method is a method in which the cargo is lifted and lowered by constantly supplying air pressure corresponding to the weight of the cargo to the cylinder. Since it was necessary to set the reference air pressure corresponding to the weight, it could not cope with changes in the weight of cargo.

The flow control method is to provide a flow control valve between the primary air and the cylinder, control the opening of the flow control valve to adjust the air supply flow rate to the cylinder, and raise and lower the cargo. Is the way. In this flow control method, the lifting operation is stopped by closing the flow control valve and shutting off the air supply to the cylinder. Immediately after closing the flow control valve, an inertial force is applied to all the mechanisms that move up and down, causing the balance between the cylinder pressure and the weight of the cargo to be lost, causing a bounce phenomenon and raising and lowering characteristics. There was a problem that it deteriorated.

[0006] The balance / flow rate control method is a balance control method which is excellent in operability but cannot cope with a change in the weight of the cargo, and a flow control method which is inferior in operability but can cope with a change in the weight of the cargo. This is a control method that can respond to changes in the weight of cargo with excellent lifting characteristics.

In this balance / flow rate control method, first, a cargo is lifted by the flow control method, and in this state, the pressure of the cylinder is taken into a storage circuit, and the pressure of the storage circuit is set as a reference air pressure corresponding to the weight of the cargo. The cylinder is driven based on the reference air pressure, and the process shifts to a balance control method. However, in this balance / flow rate control method, since all controls are performed by air, not only does the entire system become complicated, but it takes time to set a reference air pressure corresponding to the weight of cargo. Further, since the once set reference air pressure is constant, it was not possible to cope with a change in the weight of the cargo. In addition, there are many disadvantages, such as not only the necessity of adjusting the timing of operating the valve of each part, but also the reproducibility of the elevating operation is lost due to the fluctuation of the primary air pressure.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages, and comprises a mechanism for lifting and lowering a cargo, an actuator for driving the lifting and lowering mechanism, and a control for controlling the actuator. In a cargo handling machine having a part and an operating part, the weight of the cargo is always detected by a load sensor, and the cylinder is operated via an electric / pneumatic converter that operates based on an electric signal proportional to the weight signal from the load sensor. And a lifting / lowering operation force is applied between the load sensor and the actuator to lift and lower the cargo.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of this embodiment. Prop 1 and swivel 2
One end of the A-arm 4 is fixed to the fixed shaft 5 on the side plate of the main body 3 connected through the link, and the other end of the A-arm 4 is connected to one end of the C-arm 7 via the support shaft 6, and a link is provided. The arm 8, the B arm 9, the A arm 4 and the C arm 7 form a parallel link mechanism. In addition, a guide is provided for supporting the power point 10 of the parallel link mechanism in the direction perpendicular to the rotation axis of the swivel 2. Then, the operation unit 12 incorporating the hand sensor 12a and the grip unit 12b is provided at the other end of the C-arm 7. The other end of the operation unit 12 is connected to the load sensor 13. At the other end of the load sensor, a hook 14 for suspending the cargo 15 is provided.

The control section 16 includes a control board 16a, an electric / pneumatic converter 16b, a stop valve 16c, and a pressure sensor 16d. The hand sensor 12a provided on the operation unit 12 outputs to the control board 16a via the electric wire 17 and the load sensor 13 outputs to the control board 16a via the electric wire 18, respectively. Further, the pressure sensor 16d similarly outputs an electric signal to the control board 16a. The control board 16a outputs an electric signal proportional to the load sensor 13 to the electric / pneumatic converter 16b, and also outputs an electric signal for controlling the opening and closing of the stop valve 16c. Electric / pneumatic converter 16b
Is connected to the cylinder 11 via a stop valve 16c by an air pipe. Further, the pressure sensor 16
d converts the air pressure output from the electric / pneumatic converter 16b into an electric signal and outputs the electric signal to the control board 16a.

FIG. 2 is a block diagram of the control method. The load sensor 13 converts the weight of the cargo into an electric signal and outputs the electric signal to the amplifier 16e of the control board 16a. The amplifier 1
The sum of the electric signal amplified in 6e and the no-load adjuster 16f is converted to air pressure by an electric / pneumatic converter 16b. This air pressure is supplied to the cylinder 11 through the stop valve 16c, so that the cylinder 11 generates an output in proportion to the weight of the cargo, and lifts the cargo 15 via the arm mechanism. In addition, operation detector 16g
Controls the air supply of the cylinder 11 via the electric / pneumatic converter 16b and the stop valve 16c based on the electric signal from the hand sensor 12a. Further, the safety circuit 16h includes the electric signal from the pressure sensor 16d, the electric signal amplified by the amplifier 16e, and the no-load regulator 16
Based on the sum with f, the air supply to the cylinder 11 via the electric / pneumatic converter 16b and the stop valve 16c is controlled.

[0012]

From the above configuration, the operation will be described with reference to FIG. 1. First, when lifting the cargo 15 from the floor to the air, a person grasps the grip portion 12b and the hand sensor 12a.
When the human hand detects a human hand, the operation detector 16g operates the electric / pneumatic converter 16b and the stop valve 16c, and the arm mechanism can be moved up and down. Next, when a person attempts to lift the cargo 15 by applying an operation force to the grip portion 12b, a force is applied to the load sensor 13 by the operation force applied by the person. The load sensor 13 converts the applied force into an electric signal and outputs the electric signal to the amplifier 16e. This amplifier 16e
Amplifies the electric signal so that the force applied to the load sensor 13 and the output of the cylinder 11 are in a state of equilibrium, so that the signal obtained from the load sensor 13 is amplified by the amplifier 16e.
The output of the cylinder 11 which is in equilibrium with the operating force is obtained via the electric / pneumatic converter 16b. The force of the cargo 15 applied to the floor at this time is only the difference between the weight W of the cargo 15 and the output force of the cylinder 11. Since the above-mentioned action is always promptly processed, the force of the cargo 15 applied to the floor decreases promptly when a human continues to apply an operating force, and the weight W of the cargo 15 and the output of the cylinder 11 match. The cargo 15 rises in the air. Next, in order for a person to lift and lower the cargo while the cargo 15 is floating in the air, when an operation force is applied to the grip portion 12b, the output of the cylinder 11 proportional to the signal of the load sensor 13 is always obtained. The arm mechanism moves up and down. The operation of raising and lowering the cargo 15 lifted in the air is as follows. First, when a person applies an operating force to raise the cargo 15 in a speed-up state, the force applied to the load sensor 13 is the stationary state of the cargo 15. , The electric signal output from the load sensor 13 and the output of the cylinder 11 proportional to this electric signal also become larger than the amount required for the stationary state of the cargo load 15, and the operation of the person The power will be reduced. This action also works in the case of the descent deceleration state,
In the ascending and decelerating states and the descending and accelerating states, the operation is reversed, and in any case, the operation force of the person is reduced. Furthermore, when the cargo handling object 15 lands, the operation is the reverse of the case where the cargo handling material 15 is lifted, and the force applied to the floor by the cargo handling material 15 is such that the output from the cylinder 11 is rapidly reduced by the operation force of the person. Finally, all the weight W of the cargo 15 is deposited on the floor, and the cargo 15 is brought into a landing state.

When a person releases his / her hand from the grip portion 12d, the operation detector 1 is operated based on the electric signal of the hand sensor 12a.
6g stops the electric / pneumatic converter 16b, shuts off the air supply to the cylinder 11 by the stop valve 16c, and holds the arm mechanism. From this state, when the person again tries to lift the cargo load 15 by gripping the grip portion 12d, the operation is the reverse of the above-described operation, and the device can be moved up and down. At this time, the signal of the sum of the amplifier 16e and the no-load regulator 16f is compared with the electric signal of the pressure sensor 16d by the safety circuit 16h, and the output of the electric / pneumatic converter 16b is set to a level at which the cargo 15 can be maintained. If it is determined, the air is supplied to the cylinder 11 by the stop valve 16c, and the arm mechanism is shifted to a vertically movable state. Further, the above-described safety circuit 16h is an electric / pneumatic converter 16
b and the air piping have failed and the correct air pressure is no longer supplied, ie, the electric-pneumatic converter 16b
Is determined to be at a level at which the cargo 15 cannot be maintained, the air supply to the cylinder 11 is shut off by the stop valve 16c and the arm mechanism is stopped immediately.

[0014]

[Effects] From the above configuration and operation, the effects can be described. Compared with the balance control method using a load sensor or the conventional control method in which all the controls are performed by air, the present invention always reduces the weight of the cargo. The cylinder is driven through an electric / pneumatic converter that operates based on an electric signal that is detected by a load sensor and is proportional to the weight signal from the load sensor, and applies a vertical operation force between the load sensor and the actuator. By using the electric control method for lifting and lowering the cargo, there is no need to switch the control method, and it is possible to respond not only to changes in the weight of the cargo, but also to changes in the weight after the cargo is lifted. In addition, changes in the weight of the cargo during acceleration and deceleration are reflected in the electric signal input to the electric / pneumatic converter. Compared to the conventional balance control method using a load sensor and the balance control method of a pneumatic cargo handling machine where the reference air pressure is always set to a constant value, the lifting characteristics of the cargo handling machine match the human will. Therefore, good operability can be obtained. Also, a hand sensor for detecting the presence or absence of a human hand is provided on the operation unit. If this hand sensor does not detect a human hand,
The air pressure converter is stopped, the air supply to the air cylinder is shut off by the stop valve, and the electric / pneumatic pressure is maintained while the arm mechanism, which accounts for a relatively large percentage of the operation time of the pneumatic cargo handling machine, is held. By stopping the converter, the life of the electric / pneumatic converter can be improved, and the total air consumption can be reduced. In addition, a pressure sensor is provided at the output of the electric / pneumatic converter, and the pressure signal detected by this pressure sensor is compared with the input signal of the electric / pneumatic converter.When it is determined that the cargo cannot be held, a stop valve is used. By having a safety circuit that shuts off the air supply to the air cylinder and keeps the internal pressure, people can release their grips,
Stop the air pressure transducer, shut off the air supply to the cylinder with the stop valve, and hold the arm mechanism. In this state, when a person again tries to lift the cargo by grasping the grip part, air is supplied to the cylinder by the stop valve while the air pressure output from the electric / pneumatic converter can sufficiently maintain the weight of the cargo. Therefore, even when the cargo is lifted, the cargo can be safely and quickly moved from the holding state to the vertically movable state without falling. Furthermore, if the air pressure output from the electric / pneumatic converter due to the malfunction of the electric / pneumatic converter and the air pipe cannot maintain the weight of the cargo sufficiently due to the above-described action, the arm is provided by the stop valve. In order to quickly hold the mechanism, the pneumatic cargo handling machine is more secure than the conventional pneumatic cargo handling machine.

Further, by performing the control with electricity, the configuration can be simplified and the size can be reduced, and the cost can be reduced. Furthermore, it is no longer necessary to take into account the deterioration of the response speed due to pipe resistance and the complicated and difficult adjustment due to the inconsistency of the response characteristics of each valve, which must be taken into account in conventional pneumatic equipment. In addition, since the correction is performed by the feedback circuit held inside the electric / pneumatic converter, the reproducibility of the raising / lowering operation with respect to the fluctuation of the primary air pressure can be ensured.

[0016]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention.

FIG. 2 is a functional explanatory diagram (block diagram) of an embodiment of the present invention.

[Explanation of symbols]

1 support 2 swivel
3 Main unit 4 A arm 5 Fixed axis
6 Support shaft 7 C arm 8 Link arm
9 B arm 10 Power point 11 Cylinder
12 operation part 12a hand sensor 12b grip part
13 load sensor 14 hook 15 cargo
16 Control unit 16a Control board 16b Electric / pneumatic converter 16c Stop valve 16d Pressure sensor
16e amplifier 16f no-load regulator 16g operation detector
16h Safety circuit 17 Electric wire 18 Electric wire W Weight of cargo

Claims (3)

[Claims] 1. A cargo handling machine having a mechanism for lifting and lowering a cargo, an actuator for driving the lifting / lowering mechanism, and a control unit and an operation unit for controlling the actuator. The cylinder is driven via an electric-to-pneumatic converter that operates based on an electric signal proportional to the weight signal from the load sensor, and a lifting operation force is applied between the load sensor and the actuator. An electric control method for a pneumatic cargo handling machine, characterized by lifting and lowering a material. 2. An operation unit having a hand sensor for detecting the presence or absence of a human hand. When the hand sensor does not detect a human hand, the electric / pneumatic converter is stopped and the stop valve is shut off. The pneumatic cargo handling machine according to claim 1, wherein the supply air pressure to the cylinder is stopped by (1). 3. A pressure sensor is provided at an output of the electric / pneumatic converter, and a pressure signal detected by the pressure sensor is connected to an electric / pneumatic converter.
2. A pneumatic cargo handling device according to claim 1, further comprising a safety circuit for shutting off a stop valve to maintain the internal pressure of the cylinder when it is determined that the cargo cannot be held when the input signals of the pneumatic converter are compared. Transporter.