JPH0748863A - Revolving hydraulic circuit for construction machine - Google Patents

Abstract

PURPOSE:To improve the safety of a construction machine by preventing the quick revolution of the upper revolving superstructure of the construction machine. CONSTITUTION:A bypass oil path 12 connecting two main pipes 10, 11 connected to the driving hydraulic motor 9 of an upper revolving superstructure is provided. A pilot operation type communicating valve 13 is inserted in the bypass oil path 12. The pilot oil pressure of a revolution operation section 17 is fed to the communication side pilot port 14 of the communicating valve 13 via a pilot oil path 15 and a shuttle valve 16. A cutoff side pilot port 23 is connected to the extension side oil path 25 of a boom cylinder 8 via an oil path 24. When a revolution lever 18 is operated to start the hydraulic motor 9, the pilot oil pressure is applied to the communication side pilot port 14 of the communicating valve 13. The communicating valve 13 keeps the communication or cutoff state in response to the holding pressure of the boom 6 of the boom cylinder 8. When a boom is erected and the holding pressure of the boom 6 is low, the main pipes 10, 11 are communicated, the revolving acceleration of the upper revolving superstructure is decreased, and the quick revolution is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing hydraulic circuit for a construction machine, and more particularly to a hydraulic circuit for a construction machine used in a power shovel.

[0002]

2. Description of the Related Art A conventional construction machine such as a power shovel of this kind supplies pilot hydraulic pressure to a directional control valve for turning by operating an operating lever, and switches the directional control valve to a right turning position or a left turning position. Then, the hydraulic motor for driving the upper swing body is driven. By operating the operation lever in the other direction, the directional control valve for the boom cylinder is switched to raise or lower the boom. Then, by performing a combined operation of the operation levers on the opposite sides, it is possible to perform an upright operation or an inversion operation of the boom while turning the upper revolving structure.

[0003]

Conventionally, since the turning acceleration of a power shovel changes depending on the posture of the boom, it accelerates gently when the moment of inertia is large while the boom is tilted. When the moment of inertia is small due to standing up, sudden acceleration may occur. Therefore,
The operator gently operates the operation lever according to the posture of the boom to prevent the boom from suddenly accelerating. However, if the operating lever is suddenly operated while the boom is upright, the boom suddenly turns, which is dangerous.

Therefore, there arises a technical problem to be solved in order to prevent the accidental sudden turn and improve the safety of the construction machine. The present invention aims to solve the problem. To do.

[0005]

DISCLOSURE OF THE INVENTION The present invention is proposed in order to achieve the above object, and in a construction machine having an upper revolving structure, a lower traveling structure and a boom, the upper revolving structure is The two main pipelines connected to the drive hydraulic motor are connected via a communication valve, and the pilot hydraulic pressure of the swing operation part is connected to the communication side pilot port of the communication valve, and the extension side oil of the boom cylinder is connected. A swing hydraulic circuit for a construction machine in which a hydraulic pressure in a chamber is connected to a shut-off side pilot port of the communication valve.

[0006]

The two main pipes of the hydraulic motor for driving the upper swing body are connected by the pilot operated communication valve.
The pilot hydraulic pressure of the turning operation portion is connected to the communication side pilot port of the communication valve, and the hydraulic pressure of the extension side oil chamber of the boom cylinder is connected to the shutoff side pilot port.
When the swing operation section is operated and the pilot hydraulic pressure is applied to the communication side pilot port, the boom is tilted forward and the boom holding pressure of the boom cylinder is high. The spool does not move and remains in the non-communication state. On the other hand, when the boom is in the upright state and the holding pressure of the boom is low, the spool of the communication valve is switched by the pilot hydraulic pressure on the operating portion side so that the two main pipelines are communicated.

When the two main pipelines communicate with each other,
The pressure oil in the supply-side main pipe passes through the communication valve and is diverted to the return-side main pipe to reduce the acceleration of the hydraulic motor.
Thus, when the turning operation is performed, when the inertia moment is small and the holding pressure of the boom is low, the communication valve communicates with each other to limit the turning acceleration. Further, when the inertia moment is large and the holding pressure of the boom 6 is high, the communication valve does not maintain the shut-off state and holds the pressure of the main conduit to reduce the swing speed of the upper swing body.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 shows a power shovel as an example of a construction machine, in which a traveling body 2 such as a crawler is provided below a machine body 1, and an upper revolving body 5 including a cabin 3 and weights 4 is provided above the machine body 1. The upper swing body 5 is swingable in the horizontal direction about the axis L, and a boom 6 of an excavator is attached to the side of the cabin 3. Also, 7
Is a door of the cabin 3, and the body 1 and the boom 6
A boom cylinder 8 for moving the boom 6 up and down is provided between and. When the turning acceleration of the upper swing body 5 is α, the swing acceleration α is the upper swing body 5
If the moment of inertia of is I, then α∝1 / I, which is inversely proportional to the moment of inertia I. Therefore, when the inertia moment I is large, the acceleration is small, and when the inertia moment I is small, the acceleration is large.

At the position of the chain line in the drawing in which the boom 6 is turned upside down, the inertia moment I is large and the holding pressure of the boom 6 of the boom cylinder 8 is also high, so that the boom 6 is erected upright. At the position indicated by the solid line in the figure, the inertia moment I is small, and the holding pressure of the boom cylinder 8 on the boom 6 is also low. Therefore, the holding pressure of the boom 6 of the boom cylinder 8 can be used as a substitute value for the inertia moment I.

FIG. 2 shows a hydraulic circuit diagram. Reference numeral 9 denotes a hydraulic motor for driving the upper swing body 5, and a bypass oil passage 12 connecting between two main pipelines 10 and 11 connected to the hydraulic motor 9. And a pilot operated communication valve 13 is inserted in the bypass oil passage 12. Then, the pilot oil pressure of the turning operation portion 17 is supplied to the communication side pilot port 14 of the communication valve 13 via the pilot oil passage 15 and the shuttle valve 16. In addition, 18 is a turning operation lever, 1
Reference numerals 9 and 20 are control valves, 21 is a pilot pump, and 22 is a tank. In addition, shut-off pilot port 2
3 is an extension side oil passage 2 of the boom cylinder 8 via an oil passage 24.
Connected to 5.

The figure shows a state in which the turning operation lever 18 is in the neutral position and the hydraulic motor 9 is stopped.
In this case, the spool of the communication valve 13 has the shutoff position 1
3b, the bypass oil passage 12 is cut off. Next, the operation of the hydraulic circuit of the present invention will be described.
First, by turning the turning operation lever 18 in either the right turning direction or the left turning direction of the machine body 1, the hydraulic motor 9 is brought into a driving state, and the pilot oil is fed from the pilot pump 21 via the control valve 19 or 20. Road 26 or 27
Pilot oil is discharged to. And shuttle valve 16
And, pilot pressure is applied to the communication side pilot port 14 of the communication valve 13 through the oil passage 15 and urges in the communication direction.

Here, when the boom 6 shown in FIG. 1 is turned over like the position of the chain line in the drawing and the holding pressure of the boom 6 of the boom cylinder 8 is high, the communication valve 13 is shut off via the oil passage 24. Since a high pilot pressure is applied to the side pilot port 23, the spool of the communication valve 13 does not move and maintains the non-communication state. On the other hand, when the boom 6 stands up and the holding pressure of the boom 6 of the boom cylinder 8 is low as shown by the solid line in the figure, the pilot pressure to the shutoff side pilot port 23 is also low, When the pilot pressure on the turning operation lever 18 side exceeds a certain value, the spool of the communication valve 13 is switched from 13b to 13a, and the two main pipelines 10 and 11 are communicated.

When the communication valve 13 is opened, 2
The main pipelines 10 and 11 of the book communicate with each other, and the pressure oil in the supply-side main pipeline 10 or 11 passes through the communication valve 13 and returns-side main pipeline 1
Since the flow is divided into 1 or 10, the acceleration of the hydraulic motor 9 is reduced. Thus, when the turning operation is performed, when the inertia moment I is small and the holding pressure of the boom 6 is low, the communication valve 13 communicates to act to limit the turning acceleration. Further, when the inertia moment I is large and the holding pressure of the boom 6 is high, the communication valve 13 does not communicate, and the pressure of the main pipelines 10 and 11 is maintained to reduce the swing speed of the upper swing body 5. It does not interfere with workability.

The present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention extends to such modifications.

[0015]

As described in detail in the above one embodiment, the present invention has a communication valve interposed between two main pipes of a hydraulic motor for driving an upper swing body in, for example, a construction machine. . Then, the pilot oil passage of the operating portion is connected to the communication side pilot port of the communication valve, and the holding pressure of the boom cylinder is applied to the shutoff side pilot port of the communication valve. Therefore, when the boom is in the upturned state and the holding pressure of the boom is high, the communication valve does not communicate with each other, and the pressure in the main pipe line is retained so that the swing speed of the upper swing body is not reduced. or,
When the boom is in the standing state and the holding pressure of the boom is low, the spool of the communication valve is switched by the pilot hydraulic pressure on the operating portion side so that the two main pipelines are communicated.

When the two main pipelines communicate with each other, the pressure oil in the supply-side main pipeline is diverted to the return-side main pipeline through the communication valve, and the acceleration of the hydraulic motor is reduced. Regardless of the boom posture, the same turning acceleration is always obtained, and sudden turning of the upper swing body of the construction machine can be prevented, and the safety of the construction machine can be improved.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of an embodiment of the present invention.

[Explanation of symbols]

 2 Lower traveling body 5 Upper revolving structure 6 Boom 8 Boom cylinder 9 Hydraulic motor 10, 11 Main line 13 Communication valve 14 Communication side pilot port 23 Shutdown side pilot port

Claims (1)

[Claims] 1. In a construction machine having an upper revolving structure, a lower traveling structure and a boom, two main pipelines connected to a hydraulic motor for driving the upper revolving structure are connected via a communication valve. Further, the pilot hydraulic pressure of the turning operation portion is connected to the communication side pilot port of the communication valve, and the hydraulic pressure of the extension side oil chamber of the boom cylinder is connected to the shutoff side pilot port of the communication valve. Swing hydraulic circuit of construction machinery.