JPH07112912B2 - Crane hydraulic control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic control device for a crane.

[Prior Art] Conventionally, in a small-sized crane, a worm gear is diffracted between a hydraulic motor that rotates a pedestal of the crane and the pedestal, and the rotation of the hydraulic motor is decelerated by the worm gear, and the deceleration is performed. The rotation caused the pedestal to turn.

[Problems to be Solved by the Invention] With such a conventional drive configuration, when a load located at a position apart from directly below the crane boom is hoisted by a rope, the hoisting of the load laterally causes the boom to move laterally. A force acts and its lateral force naturally pulls the boom to just above the load, pulls the boom directly above it and at the same time winds up the suspended load, such a so-called suspended load center cannot be operated. It will be.

Even if such a lateral force is applied to the crane boom, the worm gear is interposed between the pedestal and the hydraulic motor as described above, so that the lateral force acting on the boom causes This is because the hydraulic motor cannot be freely driven from the pedestal side, and as a result, the suspended load center cannot be conveniently operated.

Also, in a large crane, the hanging load center can be operated, but the brake device in the hydraulic motor is designed to apply the brakes by the pedaling force separately from the pedestal driving operation lever or the lifting load hoisting operation lever. Therefore, the operation requires inexperienced operation of the pedal effort and the manual operation lever, which is inconvenient.

An object of the present invention is to provide a crane hydraulic control device that improves the conventional inconvenience as described above and enables a suspended load center only by manual operation.

[Characteristics of the Invention] A first switching valve 2 and a counterbalance valve 3 are provided between a hydraulic power source 1 and a hydraulic motor 5 for driving a crane base, and the first switching valve 2 is at the time of its neutral setting. The pipeline 1c from the hydraulic source is opened to the reservoir 4 (set to the switching position 2B), and the pipeline is opened when the drive is set (set to the switching position 2C or 2A).
In the conventional crane hydraulic system configured to increase the pressure in the 1c portion, the hydraulic motor 5 is provided with the brake hydraulic actuator 6, and the second switching valve 8 or 80 is normally connected to the hydraulic actuator 6 through the pipeline 1c. As a result, a: When the first switching valve 2 is set to the neutral position, the pipeline 1c is set to the atmospheric pressure and the hydraulic motor 5 is braked via the brake 5a. B: The first switching valve 2 When the drive is set to, the brake 5a is released by the hydraulic pressure in the pipeline 1c that has been boosted.

Also, when the hanging load center is set and the first switching valve 2 is set to neutral and the crane lifting load operating lever is operated,
The second switching valve 8 or 80 is set to a position for the hanging load center, which causes pressure oil from a predetermined hydraulic pressure source to be pumped to the pilot pipe 3c of the counterbalance valve 3 and the hydraulic actuator 6.

As a result, the brake 5a is released, and the conduits for sending hydraulic pressure to the hydraulic motor 5 and the conduits 5c and 5d for returning the same are provided.
Both are opened to the reservoir 4, and as a result, the hydraulic motor 5 for driving the crane pedestal is released from both the hydraulic drive and the mechanical braking mechanism 5a, so that a so-called hanging load center is possible.

[Examples] Hereinafter, the present invention will be described based on Examples.

FIG. 1 is a system diagram showing a crane hydraulic control device as an embodiment of the present invention.

In FIG. 1, the discharge line 1b from the hydraulic source 1 is a back pressure valve.
1a, check valve 2b, switching valve 2, hydraulic line 2c or 2d,
It is connected to a hydraulic motor 5 via a counterbalance valve 3 and a hydraulic line 5b or 5c, and the hydraulic motor 5 is a hydraulic motor for driving a pedestal of a small crane to rotate. The branch line from the hydraulic line 1c opens to the reservoir 4 only at the neutral switching position 2B of the switching valve 2.

When both pilot pipes 3a and 3c are open to the atmosphere, the counterbalance valve 3 sets its switching position to neutral 3B by an internal spring biasing force, and only the pilot pipe 3a is boosted. However, when the pilot pipe 3c remains at atmospheric pressure, the switching position is set to 3A by the hydraulic pressure of the pilot pipe 3a, and conversely, only the pilot pipe 3c is boosted and the pilot pipe 3a remains at atmospheric pressure. When it is, the switching position is set to 3C by the hydraulic pressure of the pilot pipe 3c.

Check valves 5d and 5e are provided between the hydraulic lines 5b and 5c.
And check valves 5f and 5g are interposed, and the hydraulic pipe line 7a between the check valve 5d and the check valve 5e is connected to the reservoir 4 via the relief valve 7 and the pipe line 7b.

Further, the discharge line 1b from the hydraulic pressure source 1 and the hydraulic line 1c after exiting the back pressure valve 1a are respectively connected to a switching valve 8, and the switching valve 8 connects the pilot pipe 3c and the hydraulic actuator 6. It is connected to both push-out chambers 6e.

When the hydraulic pressure is not generated in the displacement chamber 6e, the hydraulic actuator 6 acts on the brake 5a by the urging force of the spring 6a via the piston 6b to brake the hydraulic motor 5, and conversely, in the displacement chamber 6e. When hydraulic pressure is generated,
The hydraulic pressure pushes up the piston 6b against the biasing force of the spring 6a, thereby releasing the brake 5a.

The operation of the configuration of the above embodiment will be described below.

Normally, the driver places the switching valve 8 in a state in which the current to the solenoid 8a is cut off, and as a result, the switching valve 8 is
The switching position is set to 8A by the biasing force of the spring 8b.

In this normal state, when the switching valve 2 is set to the neutral position of the switching position 2B by operating the lever 2a, the discharge pressure oil from the hydraulic pressure source 1 passes through the discharge pipe line 1b, the back pressure valve 1a and the hydraulic pressure line 1c. The branch pipe is opened from the switching valve 2 to the reservoir 4.

Therefore, in this state, the hydraulic motor 5 is not driven by the pressure oil discharged from the hydraulic source 1,
Moreover, the displacement chamber 6e in the hydraulic actuator 6 is opened to the reservoir 4 via the orifice 6d, the switching valve 8, the hydraulic line 1c and the switching valve 2, so that the hydraulic motor 5 is braked by the biasing force of the spring 6a. It is in a state of

For guidance of the above neutral position, by operating the leave 2a,
When the switching valve 2 is set to the switching position 2C, the switching valve 2 closes the relationship of the hydraulic line 1c to the reservoir 4 via the switching valve 2 at the neutral position.
A hydraulic pressure is generated in the valve, and the hydraulic pressure is sent to the displacement chamber 6e via the switching valve 8 and the check valve 6c, and as a result, the brake 5a is opened. At the same time, the pressure oil in the hydraulic line 1c is pressure-fed to the hydraulic line 2d via the check valve 2b and the switching valve 2, and the pressure feed causes the hydraulic pressure in the hydraulic line 2d to flow through the orifice 3d and the pilot pipe 3c. The counter balance valve 3 is set to the switching position 3C via the.

As a result, the pressure oil that has been pressure-fed to the hydraulic line 2d causes the hydraulic motor 5 to rotate in one direction through the counterbalance valve 3 and the hydraulic line 5c, and the pressure oil that has completed its rotary work is It is opened to the reservoir 4 via the passage 5b, the counter balance valve 3, the hydraulic line 2c and the switching valve 2.

When the lever 2a is returned to the switching position 2B again from this state, both the hydraulic lines 2c and 2d are opened to the reservoir 4 as described above, and the pilot lines 3a and 3c become the atmospheric pressure. It is again set to the neutral switching position 3B and the hydraulic lines 5b and 5c are closed.

At this time, since the hydraulic motor 5 is driving the crane pedestal having a large inertial force, when the hydraulic motor 5 stops being driven by the pressure oil, the hydraulic motor 5 starts to act as a pump due to the inertial force, and the hydraulic pressure is maintained until now. The pump action pushes the pressure oil to the hydraulic line 5b that has been the oil return line.

However, since the hydraulic line 5b is closed in the counter balance valve 3 at this time, the pressure oil in the hydraulic line 5b, which has been boosted by the pump action of the counter-balanced valve 3, is used as the check valve 5d and the hydraulic line 7.
It is discharged to the reservoir 4 via a, the relief valve 7 and the conduit 7b. Further, at this time, the relief valve 7 is set to the hydraulic motor 5
A hydraulic brake is applied to the crane, which stops the rotation of the crane pedestal.

Similarly, when the lever 2a is operated to set the switching valve 2 to the switching position 2A, as is apparent from the above description, the pilot pipe
The pressure oil generated in 3a switches the counter balance valve 3 to the switching position 3A.
Therefore, the pressure oil pressure-fed to the hydraulic line 5b causes the hydraulic motor 5 to rotate to the other side.

The operation of rotating the hydraulic motor 5 to the other side from the hydraulic line 1c via the switching valve 2, the counterbalance valve 3 and the hydraulic line 5b is well known, and therefore its detailed description is omitted. .

The operation of rotating the pedestal of the crane (not shown) by the hydraulic motor 5 is performed as described above. Next, with the switching valve 2 set to the neutral position of the switching position 2B, The operation of the so-called hanging load center will be described.

When performing the hanging load center, a switch button (not shown) provided on a load hoisting operation lever or the like is pressed to supply a current to the solenoid 8a. As a result, the switching valve 8 is set to the switching position 8B.

Further, in this state, since the back pressure valve 1a is provided between the hydraulic source 1 and the hydraulic pipeline 1c, the hydraulic pressure is always generated in the discharge pipeline 1b.

For this reason, when the switching valve 8 is set to the switching position 8B, the pressure oil in the discharge pipe line 1b passes through the switching valve 8 and the pilot pipes 3b and 3c, and the check valve 6c pushes out the displacement chamber 6a.
Communicate with.

Thus, when the switching valve 2 is set to the switching position 2B, the pilot pipe 3a moves through the switching position 2B.
Open to the pilot pipe 3b in this state.
When the hydraulic pressure is sent from the side to the pilot pipe 3c, the hydraulic pressure of the pilot pipe 3c is maintained by the existence of the orifice 3d, and the hydraulic pressure sets the counter balance valve 3 to the switching position 3C.

Further, in this state, the switching valve 2 is still set to the switching position 2B as described above. Therefore, when the counterbalance valve 3 is set to the switching position 3C as described above, the hydraulic pipeline 5b becomes , The reservoir 4 via the switching position 3C of the counterbalance valve 3, the hydraulic line 2c and the switching position 2B of the switching valve 2.
The hydraulic line 5c is also opened to the counter balance valve 3
Switching position 3C, hydraulic line 2d and switching valve 2 switching position 2B
It will be opened to the reservoir 4 via.

This means that the hydraulic motor 5 is eventually opened hydraulically.

Further, in this state, the pressure oil is pressure-fed to the displacement chamber 6e through the switching position 8B of the switching valve 8 as described above, which means that the brake 5a is released as described above.

Therefore, in this state, the hydraulic motor 5 is released in a completely free state in terms of hydraulic drive and mechanical braking by the brake 5a.

As a result, in this state, even if the load on the crane is hoisted from a position different from the position just below the crane boom, the lateral force on the boom generated during hoisting
The boom, its pedestal, and the hydraulic motor 5 that drives it are freely swiveled, and their lateral direction causes the boom to naturally swivel directly above its load without creating significant lateral force on the boom. Enables a so-called hanging center.

In the above case, the back pressure valve 1a in FIG. 1 is always connected to the hydraulic pressure line 8c even when the switching valve 2 is set to the neutral switching position 2B and the hydraulic pressure line 1c is opened to the reservoir 4. It is designed to generate hydraulic pressure.

Therefore, if the hydraulic line 8c is connected to another hydraulic source different from the hydraulic source 1, the back pressure valve 1a can be omitted and the discharge line 1b and the hydraulic line 1c can be directly connected. .

Further, as shown in FIG. 1, the back pressure valve 1a can be used even when the hydraulic pressure required for the hydraulic pressure line 8c is drawn from the hydraulic pressure source 1.
Is necessary only when the switching valve 8 is set to the switching position 8B, the back pressure valve 1a can be provided in the switching valve 8.

FIG. 2 shows an embodiment in which a back pressure valve is provided in the switching valve, and the point different from FIG. 1 is that the back pressure valve in FIG.
Only 1a and the switching valve 8 are changed, and the switching positions 80A and 80B of the switching valve 80 are changed to the switching positions of the switching valve 8 in FIG.
Parts corresponding to 8A and 8B and having the same reference numerals indicate the same material.

The operation in FIG. 2 is as follows.

When the switching valve 80 is set to the switching position 80A, the discharge conduit 1b of the hydraulic power source 1 communicates with the hydraulic conduit 1c and the displacement chamber 6e. In this case, as described above, when the switching valve 2 is in the neutral position Displacement chamber where passage 1c becomes atmospheric pressure and the atmospheric pressure is in communication
6e is also atmospheric pressure, and when the switching valve 2 is in the other switching position 2C or 2A for driving, the hydraulic line 1c increases in pressure as described above, so that the hydraulic line 1c is in communication at this time. The push-out chamber 6e is also increased in pressure, whereby the brake 5a is released, and its action becomes the same as the action at the normal time in FIG.

Further, when the switching valve 80 is set to the switching position 80B, the back pressure valve 1a is provided between the discharge pipeline 1b and the hydraulic pipeline 1c. In this case, the same as in FIG. , Switching valve 2
Is in the neutral switching position 2B, hydraulic pressure is generated in the discharge pipe line 1b, and this hydraulic pressure is pumped to the pilot pipe 3c and the displacement chamber 6e. As a result, the action is as shown in FIG. Will be the same.

Here, the feature in FIG. 2 is that the switching valve 80 has a switching position 80.
When set to A, the discharge line 1 is directly connected without going through the back pressure valve 1a.
Since b communicates with the hydraulic line 1c, there is an advantage that energy loss due to pressure loss in the back pressure valve 1a as shown in FIG. 1 does not occur at this normal time.

[Effects of the Invention] The effects of the crane hydraulic control device according to the present invention are as follows.

When the second directional control valve 8 or 80 is provided and the second directional control valve is set to the normal position, the first directional control valve 2 is operated in a neutral state in conjunction with the operation of the first directional control valve 2. The hydraulic motor 5 is automatically braked, and the brake 5a of the hydraulic motor 5 is automatically released when the first switching valve 2 is set to be driven. Therefore, it becomes possible to operate the hydraulic motor 5 in the normal operation by operating only the first switching valve 2, and the work of the driver becomes easy.

Further, when the second switching valve 8 or 80 is set to the position of the hanging load center and the operating lever for hoisting the load is operated, the hanging load center can be easily operated. Since an excessive lateral force is not generated in the crane boom, it is possible to prevent an accident such as the crane falling due to the lateral force.

[Brief description of drawings]

FIG. 1 is a system diagram showing a crane hydraulic control device as one embodiment of the present invention, and FIG. 2 is a diagram showing the other embodiment of FIG. 1 by the same system diagram. . The main symbols used in the examples are as follows. 1: hydraulic power source, 1a: back pressure valve, 1b: discharge line, 1c: hydraulic line, 2:
Switching valve, 2c and 2d: hydraulic line, 3: counterbalance valve, 3c: pilot pipe, 3d: orifice, 4: reservoir, 5:
Hydraulic motor, 5a: brake, 5b and 5: hydraulic line, 6: hydraulic actuator, 8 and 80: switching valve.

Claims (2)

[Claims] 1. A first switching valve and a counterbalance valve are provided between a hydraulic power source and a crane pedestal driving hydraulic motor, and the first switching valve and the counterbalance valve are the first switching valve and the counterbalance valve. A third hydraulic pressure line and a second hydraulic pressure line are connected, and pressure oil for driving the hydraulic motor is pressure-fed between the counter balance valve and the hydraulic motor, or pressure oil after the driving is returned. And the fourth switching line is connected to the first switching valve, and when the switching position is set to drive the hydraulic motor, a: When the second hydraulic line is connected to the first hydraulic line and the second hydraulic line is opened to the reservoir, and b: the switching position is set to the neutral position,
Both the hydraulic line and the second hydraulic line are opened to the reservoir, and the counterbalance valve has a: the second hydraulic line is connected to the pilot line via the orifice. Communication, b: when the pilot line is opened to the reservoir, the counterbalance valve is set to the neutral position, and the third hydraulic line and the fourth hydraulic line are connected to the third hydraulic line. 1
Communication between the hydraulic line and the second hydraulic line is closed, and c: when hydraulic pressure is generated in the pilot line, the counterbalance valve is set to the drive position, and In the above configuration, the hydraulic motor is connected to the third hydraulic conduit, and the second hydraulic conduit is connected to the fourth hydraulic conduit. A hydraulic actuator that brakes the hydraulic motor when the mechanical brake to the hydraulic motor is released by pumping the hydraulic oil and the pressure oil is released to the atmosphere is provided. When the switch position is set to, the part where the discharge conduit from the hydraulic source is connected to the first switch valve is communicated with the hydraulic actuator, and b: is set to the second switch position. Pressure oil from a specified hydraulic source when the pilot pipe And said communicating the hydraulic actuator, the above-described configuration and going on crane hydraulic control device. 2. When the second switching valve is set to the second switching position, the pressure oil pressure-fed to the pilot line and the hydraulic actuator has a back pressure valve between the hydraulic source and the first switching valve. The crane hydraulic pressure control device according to claim 1, wherein the hydraulic pressure control device is interposed and uses pressure oil generated between the hydraulic pressure source and the back pressure valve.