JPH06227800A - Balance drive device for elevation arm type cargo handling device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the delay of the elevating speed and the moving speed of a loading cargo owing to the change of the load of a hydraulic cylinder occasioned by the angular change of an arm and the occurrence of instability of operation to the arm without arranging a balance weight and a balance spring, in a cargo handling device having arms driven for elevation by means of the hydraulic cylinder. CONSTITUTION:A cargo handling device is provided with two arms 26 and 28 and operated to perform elevation and movement of a loading cargo suspended from the arm 28 on the tip side of a hydraulic cylinder 18 arranged to the base end of the arm 26 on the base end side. In the cargo handling device, counter balance valves 63 are located in the respective return flow passage of oil pressure chambers 68 and 69 on both sides of the piston of the hydraulic cylinder 18 the load of which is changed according to the angles of the arms 26 an 28. The pilot port of the counter balance valve 63 is communicated with the hydraulic feed piping of the oil chamber on the opposite side through a check valve 64 to allow a flow toward the pilot port side and a throttle valve 65 connected in parallel to the check valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling apparatus provided with an arm that is driven up and down by a hydraulic cylinder. The load acting on the hydraulic cylinder for lifting and lowering is changed by changing the angle of the arm. The present invention relates to a device for preventing slowing up / down or moving speed of the arm and unstable operation of the arm.

[0002]

2. Description of the Related Art FIG. 4 is a diagram schematically showing an example of an arm of a lifting / lowering arm type cargo handling device and a direction of action of its driving force. The base end of a first arm 26 is a base end pin which is horizontally movable. The second arm 28 is pivotally supported by the swivel base 5 at 23, the second arm 28 is pivotally connected to the tip of the first arm 26, and the link 4 parallel to the second arm 28 whose one end is pivotally supported at the intermediate portion of the first arm 26.
1 and a link 42 parallel to the first arm 26, one end of which is pivotally supported at an intermediate portion of the second arm 28, and the other end of which is the lifting pin 25.
A vertical cylinder for vertically driving the lifting pin 25 and a horizontal cylinder 18 for vertically moving the base pin 23 and a vertical cylinder for driving the lifting pin 25 in the vertical direction. 15 is a structure for vertically moving a load suspended at the tip of the second arm 28.

In the cargo handling apparatus having the structure shown in FIG. 4, when the lifting pins 25 are moved up and down, the load vertically moves, and when the base pin 23 is moved, the load horizontally moves. The ascending / descending and moving speeds are proportional to the speeds of the upper and lower cylinders 15 and the horizontal cylinder 18. Therefore, if the hydraulic oil having a stable flow rate is supplied to the vertical cylinder 15 and the horizontal cylinder 18, the load 66 can be moved at a stable speed.

Therefore, conventionally, as shown in FIG. 3, the flow rate of the oil supplied to the hydraulic cylinders 15 and 18 is controlled by using the servo switching valves 55 and 60 in which the moving amount of the spool changes according to the exciting current. The speed of the hydraulic cylinders 15 and 18 was controlled. Here, the horizontal cylinder 18 driven on both sides of expansion and contraction includes the hydraulic chambers 6 on both sides of the piston 67.
Install throttle valves 65 and 65 in the return pipe from 8 and 69,
The cylinder was expanded and contracted at a constant speed.

[0005]

In the lifting arm type cargo handling apparatus, the arm is undulated when the load is moved, and the center of gravity of the arm moves up and down accordingly. Therefore, even when the height of the load is kept constant by the upper and lower cylinders 15, the arms 26 and 28 always try to be flat due to their own weight, and the horizontal cylinder 18 receives a force due to its own weight. Will affect. That is, when the arm is in a vertically standing state, the force due to the weight of the arm acting on the horizontal cylinder 18 is zero, and when the arm is in a slightly bent state near the horizontal position,
The arm serves as a booster mechanism such as a toggle link to apply a large force to the horizontal cylinder 18, and the first arm 26
When the robot stands up at an angle of 90 degrees or more, the load keeps the load at a constant height, such that the force acting on the horizontal cylinder 18 in the opposite direction acts due to its own weight, causing the arm to fall in the opposite direction. Even in the state in which the arm is engaged, the magnitude and the direction of the force acting on the horizontal cylinder 18 change depending on the angle of the arm, and the weight of the arm becomes relatively large compared to the weight of the load particularly in a large cargo handling apparatus. Therefore, depending on the angles of the arms 26 and 28, the horizontal cylinder 18
The load acting on will greatly change.

Therefore, the spool of the servo switching valve 60 is held at a fixed position, and the hydraulic chambers 6 on both sides of the horizontal cylinder 18 are held.
Even if the throttle valves 65 and 65 are put in the return pipes 8 and 69 to make the moving speed of the load constant, there is a problem that the moving speed of the load fluctuates greatly as the angle of the arm changes.

This problem is usually solved by providing a balance weight or a balance spring on the arm, but the base end of the first arm 26 is supported at a low position near the floor surface or the ground surface. If
The balance weight cannot be provided, and a large apparatus requires a large balance spring, which causes a problem that a large amount of labor is required for manufacturing and assembling the balance spring. Further, as another means, the moving speed of the load can be controlled to be constant by detecting the expansion / contraction speed of the horizontal cylinder 18 by using, for example, a linear scale and feedback controlling the servo switching valve 60. There is a problem that the device becomes expensive.

An object of the present invention is to obtain a simpler technical means for preventing a change in the moving speed of a load due to a change in the angle of the arm of the lifting arm type cargo handling apparatus.

[0009]

A balance drive device for a lifting arm type cargo handling device according to the present invention comprises two arms 26 and 28 connected to each other and a parallel link 41 which constitutes a similarity enlargement mechanism together with these two arms. , 42, and a lifting arm type cargo handling device for lifting and lowering a load suspended at the tip of the arm 28 on the tip side by hydraulic cylinders 15, 18 provided at the base end of the arm 26 on the base side. , 28
The counter balance valves 63 and 63 are provided in the return passages of the hydraulic chambers 68 and 69 on both sides of the piston of the hydraulic cylinder 18 on the side where the load changes depending on the angle of the counter balance valves 63 and 63, respectively. It is characterized in that it is controlled via a check valve 64 which allows the flow of oil to the pilot port side of the counter balance valve by the supplied oil pressure and a throttle valve 65 connected in parallel with the check valve 64. It is a thing.

[0010]

In the above structure, the feedback signal of the servo switching valve 60 is switched to one side, and the hydraulic pressure is supplied to one hydraulic chamber of the cylinder (horizontal cylinder in the illustrated embodiment) 18 in which the load changes depending on the arm angle. In this state, when the load acting on the cylinder 18 increases, the hydraulic pressure supplied increases, which causes the counterbalance valve 63 inserted in the return side flow path (the flow path of the hydraulic chamber on the opposite side). Since the pilot pressure also increases, the opening degree of the counter balance valve 63 increases, the pressure of the return side hydraulic chamber provided by the counter balance valve 63 decreases, and the load acting on the cylinder 18 rises. The cylinder 18 is canceled by the pressure drop in the hydraulic chamber.
The fluctuation of the moving speed of the piston is also prevented.

By installing the check valve 64 and the throttle valve 65 in parallel in the pipe line connected to the pilot port of the counter balance valve 63, the opening degree of the counter balance valve when the load of the cylinder 18 increases. Is quickly opened, and the counterbalance valve 63 is made slightly slower to follow when the load is reduced.
The counterbalance valve 63 prevents chattering.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a more specific arm structure and drive hydraulic circuit of a lifting arm type cargo handling apparatus will be described with reference to FIGS. In FIG. 1, a base 2 installed on the floor 1 of a factory or the like
A swivel shaft 3 is erected on the shaft 3, and a swivel base 5 is axially supported by bearings 4 and 4 on the swivel shaft 3. A hydraulic motor 6 is mounted on the swivel base 5, and a sprocket 8 connected to the hydraulic motor 6 via a clutch 7 meshes with a chain 9 fixed to the outer peripheral surface of the cylindrical portion of the base 2. When the hydraulic motor 6 is rotated while the clutch 7 is connected, the swivel base 5 automatically swivels, and when the worker pushes the swivel base 5 with the clutch 7 disengaged, the swivel base 5 swivels manually.

The swivel base 5 is provided with a vertical guide 11 and a horizontal guide 12, each of which is provided with a lifting bracket 13
And the expansion bracket 14 is guided. A rod of an upper and lower cylinder 15 provided below the lifting bracket 13 is directly connected to the lifting bracket 13. In addition, the expansion bracket 14
Is provided with a vertical elongated hole 16 and the rod end of a horizontal cylinder 18 whose head end is pivotally supported on the swivel base 5 by a pin 17 is connected to one end of a bell crank 20 pivotally supported on the swivel base 5 by a fulcrum pin 19. A pin 21 which is pivotally connected and is set up at the other end of the bell crank is provided with the elongated hole 16 of the telescopic bracket.
Is fitted to. Therefore, when the vertical cylinder 15 is expanded and contracted, the elevating bracket 13 is moved up and down, when the horizontal cylinder 18 is extended, the elastic bracket 14 moves left in the figure, and when the horizontal cylinder 18 is retracted, the elastic bracket 1
4 moves to the right in the figure.

A base pin 23 and an auxiliary base pin 24 are mounted horizontally and parallel to each other on the telescopic bracket 14, and a lifting pin 25 is mounted parallel to the base pin 23 on the lifting bracket 13. Has been done. The base pin 23 has a first
The base end of the arm 26 is pivotally supported, and the tip end of the first arm 26 is pivotally connected to the base end of the second arm 28 by an intermediate pin 27.
The tip of the second arm 28 is pivotally connected to the tip bracket 30 by a tip pin 29. On the other hand, a base end of a first auxiliary arm 32 having the same length as the first arm 26 is pivotally supported by the auxiliary base pin 24, and a tip end of the first auxiliary arm 32 is pivotally supported by an intermediate bracket 34 by a first auxiliary intermediate pin 33. The other end of the intermediate bracket 34 is connected to the tip bracket 30 via a second auxiliary intermediate pin 36 and an auxiliary tip pin 37 by a second auxiliary arm 35 having the same length and parallel to the second arm 28. There is. The intermediate bracket 34 is pivotally supported by the intermediate pin 27.

That is, each of the first arm 26 and the first auxiliary arm 32 and the second arm 28 and the second auxiliary arm 35 constitutes a parallel link mechanism.
The angle of the front end bracket 30 is kept constant regardless of the swinging movement of 28. The tip bracket 30 is provided with a hook 39 for suspending a load and a mounting seat for an attachment that holds the load.

Near the base end of the first arm 26 and the second arm 2
Near the base ends of 8, one ends of links 41 and 42 that form a parallelogrammatic link mechanism with these two arms 26 and 28 are pivoted, respectively.
The other end of 2 is pivotally connected by a lifting pin 25. The triangle formed by the base pin 23, the link pin 43 on the first arm side, and the lift pin 25 is similar to the triangle formed by the base pin 23, the intermediate pin 27, and the tip pin 29. Thus, the raising / lowering operation of the raising / lowering pin 25 is enlarged to raise / lower the load, and the horizontal movement of the base end pin 23 is enlarged to horizontally move the load.

In the hydraulic circuit of FIG. 2, reference numeral 45 is a variable flow rate pump unit, and the pump unit itself is a known one. Reference numeral 46 is a hydraulic manifold fixed to the base 2, 47 and 48 are hydraulic manifolds fixed to the swivel base, and 6, 15, and 18 are the hydraulic motors for swiveling, the upper and lower cylinders, and the horizontal cylinder described above.

The discharge oil of the pump that has entered the hydraulic manifold 46 of the base passes through the unloading switching valve 51 and is branched into three, one of which is the pressure adjusting valve 52 and the servo switching valve 53.
And is connected to the turning hydraulic motor 6 via. The second one communicates with the hydraulic chamber on the head end side of the upper and lower cylinders 15 through the pressure regulating valve 54, the servo switching valve 55, the pilot check valve 56, and the fuse valve 57 in the swivel manifold 47. To be done. This upper and lower cylinder 15
In this hydraulic circuit, the pressure oil is supplied only to the hydraulic chamber on the head end side of the cylinder, and when the servo switching valve 55 is switched to the lower side, the hydraulic pressure from the pump is controlled by the pilot check valve 56. The structure is such that it acts on the pilot port to open the pilot check valve 56, and the piston of the upper and lower cylinders 15 descends due to the weight of the arms 26, 28 and the like. It should be noted that the fuse valve 57 blocks the hydraulic flow passages and prevents the arms 26 and 28 and the load suspended thereon from falling in an emergency such as when the hydraulic hose 58 breaks.

The third hydraulic pipe branched from the discharge side of the unloading switching valve 51 passes through the servo switching valve 60, the hydraulic hoses 61 and 62, and is guided to the hydraulic manifold 48 on the swivel side. . A hydraulic chamber 68 on the head end side of the horizontal cylinder 18 is provided in the manifold 48 on the swivel side.
And two oil passages corresponding to the rod end side hydraulic chamber 69 are provided, and a counter balance valve 63 is provided in each of the oil passages. A hydraulic supply passage is provided in parallel with the counter balance valve 63. Is connected (that is, allows the inflow of oil to the cylinder 18 side). Therefore, the counter balance valve 63 functions to control the pressure in the hydraulic chamber on the return side of the horizontal cylinder 18. Then, in the pilot port of each counterbalance valve 63, there is a check valve 64 whose pressure in the pipe lines on the opposite sides allows the oil to flow into the pilot port side.
It is supplied through the throttle valve 65 connected in parallel with this.

The operation of the hydraulic circuit inside the manifold 48 of the swivel base is as described in the above section. The throttle valve 65 connected to the pilot port of the counter balance valve 63 is a variable throttle valve, and by adjusting the throttle amount, both quick response of the counter balance valve 63 and prevention of chattering are realized. In the hydraulic circuit shown in the embodiment, the pressure in the hydraulic chambers of the cylinders 15 and 18 is maintained even when the unloading switching valve 51 is switched to release the pressure supply to the cylinders 15 and 18. Servo switching valve 5
The spool locking phenomenon caused by the continuous application of high hydraulic pressure to 5 and 60 is prevented by releasing the pressure applied to the servo switching valves 55 and 60 by the and load switching valve 51 to the atmosphere when not in use. It has a structure.

In the apparatus shown in FIG. 1, the horizontal cylinder 1
8 requires the highest pressure, pump unit 45
The maximum discharge pressure is set to a value corresponding to the required pressure of the horizontal cylinder 18, and the oil pressure applied to the upper and lower cylinders 15 and the swing motor 6 is set by the pressure adjusting valves 52 and 54.

[0022]

According to the present invention described above, it is possible to effectively prevent the moving speed of the load of the lifting / lowering arm type cargo handling apparatus from changing depending on the angle of the arm, and especially for a large apparatus, a large balance weight. Since a strong balance spring is unnecessary and expensive feedback control is unnecessary, the device can be made inexpensive and compact, and the operation is stable.

[Brief description of drawings]

FIG. 1 is a side view of an example of a lifting arm type cargo handling device.

FIG. 2 is a diagram showing a drive hydraulic circuit of the apparatus of FIG.

FIG. 3 is a diagram showing a main part of a hydraulic circuit of a conventional device.

FIG. 4 is a schematic side view of a lifting arm type device.

[Explanation of symbols]

 15 Vertical cylinder 18 Horizontal cylinder 26 1st arm 28 2nd arm 41 Link 42 Link 63 Counter balance valve 64 Check valve 65 Throttle valve 68 Hydraulic chamber 69 Hydraulic chamber

Claims (1)

[Claims] 1. A base end arm comprising two articulated arms (26), (28) and parallel links (41), (42) forming a similar enlargement mechanism together with the two arms. In the lifting arm type cargo handling device that lifts and lowers the load suspended at the tip of the arm (28) on the tip side by the hydraulic cylinders (15) and (18) provided at the base end of (26), Counterbalance valves (63) and (63) are provided in the return passages of the hydraulic chambers (68) and (69) on both sides of the piston of the hydraulic cylinder (18) where the load changes depending on the angle of (28). The counterbalance valve (63) has a pilot port on the opposite side through a check valve (64) in a direction that allows the flow toward the pilot port side and a throttle valve (65) connected in parallel with the check valve (64). Balance drive device for a lifting and lowering arm type cargo handling device, characterized in that the balance drive device is connected to the hydraulic supply pipe of the hydraulic chamber.