JPH07115840B2 - Hydraulic load balancer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load balancer,
In particular, the present invention relates to a load balancer capable of transporting and moving a heavy object to a desired place with a slight force.

[0002]

2. Description of the Related Art When a heavy object such as an engine part is conveyed, a reaction force commensurate with the weight of the load is generated in advance, and a force corresponding to the load fluctuation caused by the operator's operation force is generated to lighten the heavy object. There is known a load balancer that can be transported and moved.

A conventional load balancer of this type is disclosed in Japanese Utility Model Laid-Open No. 61-197079. This is provided with an arm on which a heavy object is placed and which can be freely moved, and a balance cylinder receives a load transmitted through the arm. The balance cylinder is provided with a pneumatic cylinder, and a hydraulic weight-sensing cylinder receives the full load including the pneumatic cylinder. The pneumatic cylinder is connected to the pneumatic pressure source via a precision pressure reducing valve, and the weight sensing cylinder transmits the initial load due to the sensing load to the precision pressure reducing valve as pilot pressure.

According to such a load balancer, when a heavy load is first placed on the arm, the weight sensing cylinder receives a reaction force corresponding to the load, which is introduced as a pilot pressure into the precision pressure reducing valve. The air pressure is introduced into the balance cylinder by opening and closing the precision pressure reducing valve to respond to the load reaction force that accompanies the operation of the arm, so that it is possible to carry heavy objects in a nearly weightless state at all times. is there.

[0005]

However, since the conventional load balancer is a method of balancing operation fluctuations by air pressure, it is not possible to handle heavy objects of a ton class, and a suspension method using a crane is adopted. There were many cases. However, it is not possible to use a crane in a closed space or a place where the height of the ceiling is limited, and even if a forklift is used, delicate positioning is difficult, and a handling device with better operability is desired. It was rare.

It is an object of the present invention to provide a hydraulic load balancer capable of handling a so-called ton-class heavy object in an unloaded state, focusing on the above conventional problems.

[0007]

In order to achieve the above object, in a hydraulic load balancer according to the present invention, a mounting table is attached to the tip of a support arm pivotally attached to a support frame, and the support arm and the support are attached. In a load balancer in which a balance cylinder is arranged between the rack and the balance to support the load from the mounting table, the balance cylinder is configured by a hydraulic cylinder device, and a load from the mounting table to the hydraulic cylinder device is formed. A load detection sensor such as a load cell is attached to the transmission path, a hydraulic pressure supply path is connected to the rod side hydraulic chamber of the hydraulic cylinder device, and a hydraulic path in which a servo valve is interposed is connected to the head side hydraulic chamber. Oil that balances the initial load with the difference between the thrust on the head side and the thrust on the rod side of the hydraulic cylinder device based on the detection signal from the load detection sensor. It is generated, and was to determine the presence or absence of vertical operation force by detecting the displacement of the sensor or hydraulic chamber pressure sensor and structure provided with control means for driving and controlling the servo valve.

[0008]

According to the above construction, when a load is placed on the mounting table, the control device determines the hydraulic reaction force necessary for balancing by the detection signal from the load sensor such as the load cell or the hydraulic chamber pressure sensor, and the head side. Supply to hydraulic chamber to support initial load. When an operator's operation is applied, the load detection sensor senses the operation direction to determine the operation direction and set the pressure or speed of the servo valve. This makes it possible for humans to handle tons of heavy objects.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the hydraulic load balancer according to the present invention will be described in detail below with reference to the drawings.

FIG. 4 shows the external configuration of the load balancer according to the embodiment. The load balancer includes a main arm 12 pivotally mounted on the carriage 10, and a lift cylinder 14 is attached between the main arm 12 and the carriage 10 so that the main arm 12 can be tilted. Further, a lift arm 16 is pivotally connected to the tip of the main arm 12, and the lift arm 16 can be bent with respect to the main arm 12 so as to be able to move up and down. A mounting table 20 on which a heavy object 18 is placed is attached to the tip of the lift arm 16. The mounting table 20 is designed to always maintain a horizontal plane regardless of the operation of the main arm 12 and the lift arm 16. Therefore, the main arm 12 and the lift arm 16 are constituted by a horizontal link mechanism.

In such a structure, in order to convey the heavy load 18 in an unloaded state, the carriage 10 is provided with a balance cylinder 22 for generating a lifting operation force of the lift arm 16.
A drive control means 24 for driving and controlling this is mounted. The balance cylinder 22 is connected between the main arm 12 and the lift arm 16 so as to support a load applied through the arm 16.

Balance cylinder 22 and drive control means 24
FIG. 1 shows a specific configuration of the above. As shown in this figure, the balance cylinder 22 connecting the main arm 12 and the lift arm 16 is composed of a hydraulic cylinder device, and a piston 26 is slidably inserted therein.
This piston 26 has a rod 2 that receives a load as an axial force.
8 is integrally attached. Due to the piston 26, the inside of the cylinder 22 is moved to the upper rod-side hydraulic chamber 3 in the figure.
0A and a lower head side hydraulic chamber 30B. A constant pressure supply pipe line 31 for supplying hydraulic oil having a constant pressure is connected to one of the rod side hydraulic chambers 30A, and the other head side hydraulic chamber 30B is provided with a servo valve 32. A variable supply pipe line 34 for mounting and variably supplying hydraulic oil is connected, and is connected to a pump 36 as a hydraulic pressure source and a tank 38. Thus, by adjusting the pressure and the changing speed of the head side hydraulic chamber 30B, an oil pressure that balances the load from the lift arm 16 side including the heavy object 18 is generated, and an oil pressure that corresponds to the operating force is generated. I will support you.

Further, such a balance cylinder 22 is provided with a load cell 40 as a load detecting sensor on the load receiving surface from the lift arm 16 so that the load weight applied to the balance cylinder 22 as an axial force can be detected. I am trying. Further, pressure sensors 42A and 42B for detecting the internal pressures of the rod side hydraulic chamber 30A and the head side hydraulic chamber 30B.
And a stroke sensor 44 for detecting the stroke of the piston 26.

The drive control means 24 inputs the detection signals from these respective sensors, and the respective sensors 40, 42A, 42B and 44 are amplified by the amplifier 46 and input to the control means 24. ing. The control means 24 inputs the input signal through the A / D converter 48 to the computing unit 50.
Is input to the servo valve 32 and the necessary arithmetic processing is performed to output a drive signal to the servo valve 32.

The arithmetic processing in the arithmetic unit 50 is performed as follows. That is, the axial load F applied to the balance cylinder 22 by the detection signal from the load cell 40.
_W is obtained and taken into the calculator 50 as a load signal. Further, the position signal of the piston 26 can be taken in by the detection signal from the stroke sensor 44. Furthermore,
The hydraulic pressure in the hydraulic chambers 30A and 30B can be taken in according to the detection signals from the pressure sensors 42A and 42B. In the arithmetic unit, the axial load F _W that is initially taken in is stored in the internal memory and is stored as the initial set load. Then, the calculator 50 continuously takes in the load signal F from the load cell 40, and calculates the deviation from the initial set load F _{W in} the balance operation mode. This deviation is compared with an upper and lower threshold value ± r which is preset or automatically set in relation to the initial value so as to determine the load cell output signal F which is sequentially detected. This has the following form.

[0016]

[Formula 1] F> F _W + r At this time, it is determined that a lowering operation force is applied to the mounting table 20, and the required hydraulic pressure of the head side hydraulic chamber 30B is calculated in relation to the rod side hydraulic chamber 30A. A pressure reduction signal is output to the servo valve 32 so as to obtain the calculated hydraulic pressure.

[0017]

## EQU00002 ## F _W + r ≧ F ≧ F _W −r At this time, it is determined that the vertical operation force is not applied to the mounting table 20, and the drive signal to the servo valve 32 is not output and the current state is maintained. .

[0018]

## EQU00003 ## F _W -r> F At this time, it is determined that the raising operation force is applied to the mounting table 20, and the required hydraulic pressure of the head side hydraulic chamber 30B is calculated in relation to the rod side hydraulic chamber 30A. A pressure increase signal is output to the servo valve 32 so as to obtain the calculated hydraulic pressure.

By the way, as for the control pressure of the head side hydraulic chamber 30B, in the case of the embodiment, the reference pressure P _W is calculated with reference to the initial load value F _W, and from this reference pressure, a constant pressure is obtained. The pressure signal P _W + α or P _W −β obtained by adding α and subtracting the constant pressure β in the case of the lowering operation is output. As a result, the servo valve 32 is set so that the internal pressure of the head side hydraulic chamber 30B continues to increase at a constant rate while the raising operation signal is detected, and conversely, the internal pressure of the head side hydraulic chamber 30B continues to decrease at a constant rate while detecting the lowering signal. It is controlled and driven. The drive signal calculated by the arithmetic unit 50 is output to the servo control module 54 via the D / A converter 52, and the servo valve 32 is driven via the servo driver 56.

Here, the adjustment pressures α and β are set in the vertical operation direction at a constant rate in consideration of the piston sliding resistance of the balance cylinder 22 and the mechanical loss in the load transmission path to the balance cylinder 22. Therefore, the lift arm 16 is set so as to move up and down. For example, experimentally, appropriate adjustment pressures α and β for raising or lowering the piston 26 are obtained, and these are stored in a memory and the reference pressure is appropriately set. It is also possible to perform an addition / subtraction process on and output to the servo control module 54. Of course, the magnitude of the operating force is calculated, and the adjusting pressures α ₁ , α ₂ , ..., β ₁ , β ₂ ,. It is also possible to cause the up and down movement of the.

The control operation of the hydraulic load balancer thus constructed will be described with reference to the flow chart shown in FIG. First, the load balancer is first set to the forced mode by turning on the drive switch in the unloaded state (step 100), and the heavy load 1 is placed on the mounting table 20 in this state.
By mounting 8 on the mounting table 20, the mounting table 20 is forcibly driven to rise to a certain height (step 110).
When the heavy load 18 is placed, the weight of the load is initially detected by the load cell 40 or the pressure sensors 42A and 42B (step 120) and stored in the memory as the initial load F _W (step 130). As a result, a hydraulic reaction force commensurate with the initial load is output to the servo valve 32 so as to be generated in the head side hydraulic chamber 30B, and the heavy object 18 is held at a constant height.

Then, the balance mode for accepting the manual operation of the operator is determined (step 140), and when the balance mode is set, the control means 24 successively inputs the detection signals from the sensors such as the load cell 40. Then, in particular, the deviation between the initial set load F _W and the detected load F is calculated by the input signal from the load cell 40 (step 15
0), this is compared with the threshold value ± r, and the presence or absence of the operating force is determined based on the above-mentioned "Equation 1" to "Equation 3" (step 160). When the operating direction is the raising direction, the calculator 50 outputs the drive signal of the servo valve 32 so that the pressure in the head side hydraulic chamber 30B becomes P _W + α, and conversely the operating direction is the lowering direction. In this case, a drive signal is output so that the pressure in the head side hydraulic chamber 30B becomes P _W -β (steps 180, 190). Then, the presence / absence of a stop command is determined (step 200), and the processes in and after step 150 are repeated until the stop command is issued.

According to such a hydraulic load balancer, the balance cylinder 22 composed of a hydraulic cylinder is used.
While the mounting table 20 is positioned at a predetermined height by generating a hydraulic reaction force that opposes the initial load by the operator,
When 0 is manually operated up and down, as long as the operation is continued, the balance cylinder 22 is continuously pressurized or depressurized in the operating direction, and the heavy object 18 is unloaded in the desired direction. It can be moved. In particular, since the balance cylinder 22 is constituted by the hydraulic cylinder device, even if the placed heavy object is of the so-called ton class, it is possible to easily support the balance and move it in any direction.

In the above embodiment, an example of operation by controlling the pressure of the balance cylinder 22 has been shown, but this may be performed by controlling the ascending / descending speed of the balance cylinder 22. This is a flow chart corresponding to FIG. 2, and the output of the control operation to the balance cylinder 22 performed by the determination of the operation direction is performed by the flow rate control by the servo valve 32 as shown in steps 280 and 290. The ascending speed V _U may be calculated and set (step 280) or the descending speed V _D may be controlled and output. Other processing is the same as that shown in FIG.

As described above, in the embodiment according to the present invention, the presence or absence and the direction of vertical movement of the balance cylinder 22, which is a hydraulic cylinder, are detected by the load balancer 40, and when the operating force is continuously applied, Since the balance cylinder 22 is controlled and driven so as to be vertically moved at an appropriate movement amount or speed in consideration of sliding resistance and mechanical loss due to a piston ring or the like, when the weight of luggage is in the ton class. Can be handled easily.

As described above, the control amount of the balance cylinder 22 can be adjusted so as to be proportional to the magnitude of the operating force, or the reaction force and stroke of the balance cylinder can be controlled in proportion to the operating speed.

[0027]

As described above, according to the present invention,
The balance cylinder is composed of a hydraulic cylinder device,
A load detection sensor such as a load cell is attached to the load transmission path from the mounting table to the hydraulic cylinder device, a constant pressure supply path is connected to the rod side hydraulic chamber of the hydraulic cylinder device, and a servo valve is interposed in the head side hydraulic chamber. Variable hydraulic path is connected, the hydraulic pressure that balances the head side hydraulic pressure of the hydraulic cylinder device with the initial load is generated based on the detection signal from the load detection sensor, and the displacement of the sensor or the hydraulic chamber pressure is detected. Since the control means for driving and controlling the servo valve by determining the presence / absence of the vertical operation force is provided, it is possible to perform the vertical operation in the no-load state while sufficiently supporting the heavy load due to the hydraulic pressure. Therefore, it is possible to obtain the effect that handling of heavy goods in the ton class can be performed extremely easily.

[Brief description of drawings]

FIG. 1 is a configuration diagram of essential parts of a hydraulic load balancer according to an embodiment.

FIG. 2 is a flowchart showing an example of control of the load balancer.

FIG. 3 is a flowchart showing another control example of the same load balancer.

FIG. 4 is a side view showing an overall configuration of the load balancer.

[Explanation of symbols]

 10 Bogie 12 Main Arm 14 Lift Cylinder 16 Lift Arm 18 Heavy Object (Luggage) 20 Placement Table 22 Balance Cylinder 24 Drive Control Means 26 Piston 28 Rod 30A Rod Side Hydraulic Chamber 30B Head Side Hydraulic Chamber 31 Constant Pressure Supply Pipeline 32 Servo Valve 34 Variable Supply Pipeline 36 Pump 38 Tank 40 Load Cell 42A, 42B Pressure Sensor 44 Stroke Sensor 46 Amplifier 48 A / D Converter 50 Computing Unit 52 D / A Converter 54 Servo Control Module 56 Servo Driver

Claims (1)

[Claims] 1. A mounting table is attached to a tip of a supporting arm pivotally mounted on the supporting frame, and a balance cylinder is arranged between the supporting arm and the supporting frame to balance and support a load from the mounting table. In the load balancer configured as described above, the balance cylinder is configured by a hydraulic cylinder device, and a load such as a load cell is provided in a load transmission path of the hydraulic cylinder device.
A detection sensor is attached, a hydraulic pressure supply path is connected to the rod side hydraulic chamber of the hydraulic cylinder device, and a hydraulic path in which a servo valve is interposed is connected to the head side hydraulic chamber. Based on the above, the hydraulic pressure at which the difference between the thrust on the head side of the hydraulic cylinder device and the thrust on the rod side balances with the initial load is adjusted in the pressure in the hydraulic chamber on the head side.
The initial load to determine the presence or absence of vertical operating force is generated, and the detection of the displacement of the sensor or hydraulic chamber pressure by
A load balancer comprising a control means for driving and controlling the servo valve so that the servo valve is operated with a deviation from the weight .