JP3379777B2 - Balance drive for lifting arm type cargo handling equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling apparatus having an arm driven up and down by a hydraulic cylinder, and a hydraulic cylinder for driving up and down by changing the angle of the arm. The present invention relates to a device for preventing a load acting on a load from changing, causing a load to move up and down or to slow down a moving speed, and to prevent unstable operation of an arm. 2. Description of the Related Art FIG. 4 is a view schematically showing an example of an arm of a lifting arm type cargo handling device and an action direction of a driving force thereof. A base end of a first arm 26 is movable in a horizontal direction. The second arm 28 is pivotally connected to the tip of the first arm 26 by the base pin 23, and is parallel to the second arm 28, one end of which is pivotally supported at an intermediate portion of the first arm 26. Link 4
The other end of a link 42 parallel to the first arm 26 pivotally supported at one end at an intermediate portion between the first arm and the second arm 28 is connected to an elevating pin 25.
The lifting pin 25 is pivotally supported by the swivel 5 movably in the vertical direction, and a horizontal cylinder 18 for moving the base pin 23 in the horizontal direction and an upper and lower cylinder for driving the lifting pin 25 in the vertical direction. 15 is a structure for moving the load suspended from the tip of the second arm 28 up and down. In the cargo handling apparatus having the structure shown in FIG. 4, the cargo vertically moves when the lifting pin 25 is moved up and down, and the cargo moves horizontally when the base pin 23 is moved. The ascending / descending and moving speeds are proportional to the speeds of the vertical cylinder 15 and the horizontal cylinder 18. Accordingly, if a stable oil pressure is supplied to the upper and lower cylinders 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 oil supplied to the hydraulic cylinders 15 and 18 is controlled by using servo switching valves 55 and 60 in which the amount of movement of the spool changes according to the exciting current. The speed control of the hydraulic cylinders 15 and 18 was performed. Here, the horizontal cylinder 18 driven on both sides of the expansion and contraction has hydraulic chambers 6 on both sides of the piston 67.
Throttle valves 65, 65 are provided in the return pipe from 8, 69,
The cylinder was expanded and contracted at a constant speed. [0005] In the lifting arm type cargo handling device, the arm moves up and down when the cargo is moved, and accordingly the center of gravity of the arm moves up and down. Therefore, even in the state where the height of the cargo is maintained at a constant height 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 applies the force of the arm's own weight to the horizontal cylinder 18. Will have an effect. That is, when the arm is standing vertically, the force of the arm acting on the horizontal cylinder 18 due to its own weight is 0, and when the arm is slightly bent at a position near horizontal,
The arm serves as a boosting mechanism such as a toggle link to apply a large force to the horizontal cylinder 18.
When the robot is standing at an angle of 90 degrees or more, the load is maintained at a constant height so that the force acting on the horizontal cylinder 18 in the opposite direction is exerted by the force that causes the arm to fall in the opposite direction by its own weight. Even in this state, the magnitude and direction of the force acting on the horizontal cylinder 18 changes 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 device. Therefore, the horizontal cylinder 18 depends on the angle of the arms 26 and 28.
, The load acting on the load changes greatly. Accordingly, 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, 65 are inserted into the return lines 8, 69 to keep the moving speed of the load constant, there is a problem that the moving speed of the load greatly fluctuates with the change in the angle of the arm. Although this problem is usually solved by providing a balance weight or a balance spring on the arm, the base end of the first arm 26 is supported at a low position near the floor or the ground surface. If you have
A balance weight cannot be provided, and a large-sized device requires a large balance spring, which causes a problem that a large amount of labor is required for its manufacture and assembly. 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 using, for example, a linear scale and performing feedback control of the servo switching valve 60. There is a problem that the device becomes expensive. An object of the present invention is to provide a simpler technical means for preventing a change in the moving speed of a load caused by a change in the angle of an arm of a lifting arm type cargo handling device. [0009] [Means for Solving the Problems] balance driving device of the lifting arm type handling apparatus according to the present invention, the articulated base end
And two arms 26, 28 of the front end side, parallel to constitute a similar enlargement mechanism with the two arm link 41 and 42
2 and provided on the base end of the arm 26 on the base end side and
Oil for lifting and lowering the load suspended at the tip of the arm 28
Pressure cylinder, depending on the angle of the arms 26 and 28.
In the lifting / lowering arm type loading and unloading device having a hydraulic cylinder 18 having a variable load , counterbalance valves 63 and 63 are respectively provided in return passages of hydraulic chambers 68 and 69 on both sides of the piston of the hydraulic cylinder 18 with a variable load. Each counter balance valve 63 is provided with a check valve 64 that allows oil flow to the pilot port side of the counter balance valve by hydraulic pressure supplied to the hydraulic chamber on the opposite side, and a throttle connected in parallel to the check valve 64. It is characterized by being controlled via the valve 65. In the above construction, the feedback signal of the servo switching valve 60 is switched to one, and the hydraulic pressure is supplied to one hydraulic chamber of a cylinder (horizontal cylinder in the illustrated embodiment) 18 whose load varies depending on the angle of the arm. When the load acting on the cylinder 18 increases in the state where the pressure is supplied, the supplied hydraulic pressure increases, whereby the counter balance inserted in the return flow path (the flow path of the opposite hydraulic chamber) is increased. Since the pilot pressure of the valve 63 also increases, the opening degree of the counterbalance valve 63 increases, the pressure in the hydraulic chamber on the return side provided by the counterbalance valve 63 decreases, and the load acting on the cylinder 18 increases. Is canceled by the pressure drop in the return hydraulic chamber, and the cylinder 18
The fluctuation of the moving speed of the piston is also prevented. A check valve 64 and a throttle valve 65 are interposed in parallel in a pipe connected to the pilot port of the counterbalance valve 63, so that the opening of the counterbalance valve is increased when the load on the cylinder 18 is increased. Is opened quickly and the follow-up of the counterbalance valve 63 when the load is reduced is slightly slowed down.
The counterbalance valve 63 prevents chattering. Next, a more specific arm structure and a drive hydraulic circuit of a lifting arm type cargo handling device will be described with reference to FIGS. 1 and 2. FIG. In FIG. 1, a base 2 installed on a floor 1 of a factory or the like.
A swivel 3 is set up, and a swivel 5 is supported by bearings 4 and 4 on the swivel 3. A hydraulic motor 6 is mounted on the swivel 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 turns. When the clutch 7 is turned off and the operator presses the swivel base 5, the swivel base 5 is manually swiveled. The swivel 5 is provided with a vertical guide 11 and a horizontal guide 12, each of which has a lifting bracket 13.
The extension bracket 14 is guided. The lifting bracket 13 is directly connected to a rod of an upper and lower cylinder 15 provided below the lifting bracket 13. Telescopic bracket 14
Is provided with an elongated hole 16 in the vertical direction, and a rod end of a horizontal cylinder 18 whose head end is pivotally supported by the pivot table 5 by a pin 17 is connected to one end of a bell crank 20 pivotally supported by the pivot table 5 by a fulcrum pin 19. The pin 21 which is pivotally connected and is erected at the other end of the bell crank is connected to the elongated hole 16 of the telescopic bracket.
Is fitted. Therefore, the elevating bracket 13 is moved up and down by extending and retracting the vertical cylinder 15, and when the horizontal cylinder 18 is extended, the telescopic bracket 14 moves to the left in the figure.
4 moves to the right in the figure. A base pin 23 and an auxiliary base pin 24 are mounted on the telescopic bracket 14 horizontally and parallel to each other, and a lift pin 25 is mounted on the lift bracket 13 in parallel with the base pin 23. Have been. The first pin 23
The proximal end of the arm 26 is pivotally supported, and the distal end of the first arm 26 is pivotally connected to the proximal end of the second arm 28 with an intermediate pin 27,
The tip of the second arm 28 is pivotally connected to a tip bracket 30 by a tip pin 29. On the other hand, the base end of a first auxiliary arm 32 having the same length as the first arm 26 is pivotally supported by the auxiliary base end pin 24, and the distal end of the first auxiliary arm 32 is pivotally supported by a first auxiliary intermediate pin 33 to an intermediate bracket 34. The other position of the intermediate bracket 34 and the end bracket 30 are connected via a second auxiliary intermediate pin 36 and an auxiliary end pin 37 with a second auxiliary arm 35 having the same length and parallel to the second arm 28. I have. The intermediate bracket 34 is pivotally supported by the intermediate pin 27. That is, the first arm 26 and the first auxiliary arm 32 and the second arm 28 and the second auxiliary arm 35 each constitute a parallel link mechanism.
The angle of the tip bracket 30 is kept constant irrespective of the swinging operation of the tip 28. The tip bracket 30 is provided with a hook 39 for suspending a load and an attachment seat for an attachment for holding the load. Near the base end of the first arm 26 and the second arm 2
Near the base end of the link 8, one end of each of links 41 and 42 constituting a parallelogram link mechanism with these two arms 26 and 28 is pivotally supported.
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 elevating pin 25 is similar to the triangle formed by the base pin 23, the intermediate pin 27, and the tip pin 29. Then, the lifting operation of the lifting pins 25 is enlarged to lift and lower the load, and the horizontal movement of the base end pin 23 is expanded to move the load horizontally. In the hydraulic circuit shown in FIG. 2, reference numeral 45 denotes a variable flow rate pump unit, which is a known pump unit. Reference numeral 46 denotes a hydraulic manifold fixed to the base 2, 47 and 48 denote hydraulic manifolds fixed to the swivel table, and 6, 15, and 18 denote the above-described hydraulic motor for turning, a vertical cylinder, and a horizontal cylinder. The pump discharge oil entering the base hydraulic manifold 46 is branched into three through an unloading switching valve 51, one of which is a pressure adjusting valve 52 and a servo switching valve 53.
Through the hydraulic motor 6 for turning. The second valve passes through a pressure regulating valve 54, a servo switching valve 55, a pilot check valve 56, and further passes through a fuse valve 57 in a manifold 47 of a swivel base to communicate with a hydraulic chamber on the head end side of the upper and lower cylinders 15. Is done. This vertical cylinder 15
In this hydraulic circuit, pressure oil is supplied only to the hydraulic chamber on the head end side of the cylinder. When the servo switching valve 55 is switched to the descending side, the hydraulic pressure from the pump causes the pilot check valve 56 Acting on the pilot port, the pilot check valve 56 is opened, and the piston of the upper and lower cylinder 15 is lowered by its own weight of the arms 26 and 28. The fuse valve 57 shuts off the hydraulic flow path in an emergency such as when the hydraulic hose 58 is broken, thereby preventing the arms 26 and 28 and the cargo suspended therefrom from dropping. The third hydraulic pipe branched from the discharge side of the unloading switching valve 51 passes through the servo switching valve 60, passes through the hydraulic hoses 61 and 62, and is guided to the hydraulic manifold 48 on the turning table side. . A hydraulic chamber 68 on the head end side of the horizontal cylinder 18 is provided in the manifold 48 on the turntable side.
And two hydraulic passages respectively corresponding to the hydraulic chamber 69 on the rod end side. A counterbalance valve 63 is interposed in each of the two oil passages, and a hydraulic supply path is provided in parallel with the counterbalance valve 63. to form a (i.e. to permit the flow of oil into the cylinder 18 side) check valve 70 are connected. Therefore, the counterbalance valve 63 has the function of controlling the pressure in the hydraulic chamber on the return side of the horizontal cylinder 18. The pilot port of each counter balance valve 63 has a check valve 64 that allows the pressure of the pipes on the opposite sides to allow oil to flow into the pilot port,
The air is supplied through a 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 section of the operation. 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, 18 is maintained even when the supply of the pressure to the cylinders 15, 18 is released by switching the unloading switching valve 51. And the servo switching valve 5
The spool lock phenomenon caused by the continuous high pressure of the hydraulic pressure applied to the servo switching valves 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.
8 requires the highest pressure, the pump unit 45
Is set to a value corresponding to the required pressure of the horizontal cylinder 18, and the hydraulic pressure applied to the upper and lower cylinders 15 and the swing motor 6 is set by the pressure adjusting valves 52 and 54. 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 loading / unloading device from being changed depending on the angle of the arm. Since large balance weights and strong balance springs are not required, and expensive feedback control is not required, the apparatus can be made inexpensive and compact, and the operation is stable.

[Brief description of the drawings] FIG. 1 is a side view of an embodiment of a lifting arm type cargo handling device. FIG. 2 shows a drive hydraulic circuit of the device 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 Second arm 41 links 42 links 63 Counterbalance valve 64 Check valve 65 Throttle valve 68 Hydraulic chamber 69 hydraulic chamber

Claims (1)

(57) two arms of the Patent Claims 1] articulated proximal side and a distal side (26), and (28), to form a similar enlargement mechanism with the two arms Provided at the base of the parallel link (41), (42) and the base arm (26), and at the tip of the distal arm (28).
A hydraulic cylinder that lifts and lowers a suspended load
Oil whose load changes depending on the angle of the arms (26) and (28)
In lifting arm type handling apparatus that includes a pressure cylinder (18), said piston on both sides of the hydraulic chamber of the hydraulic cylinder load changes (18) (68), each counterbalance valve to the return flow path (69) ( 63) and (63) are provided, and the pilot port of each counter balance valve (63) has a check valve (64) in a direction allowing flow toward the pilot port side and a throttle valve connected in parallel to the check valve (64). (65) is connected to the hydraulic pressure supply pipe of the hydraulic chamber on the opposite side through (65), the balance drive device of the lifting arm type cargo handling device.