JPS5914531Y2 - Swing drive/brake circuit for construction machinery - Google Patents

Description

[Detailed Description of the Invention] Generally, the turning of a construction machine is performed by operating a turning motor by operating a directional control valve, and controlling it by a hydraulic brake valve that is a combination of a counterbalance valve and a relief valve.

This method is effective in protecting the swing motor from external overloads and preventing overspeeding when working on slopes.

The present invention relates to a swing drive and braking circuit for construction machinery equipped with this hydraulic brake valve.

In conventional swing drive/brake circuits, the relief valve provided in the brake valve is used for pressure control for both starting and braking.

That is, the starting torque and braking torque of the swing motor are always equal.

In such a swing circuit, the set pressure of the relief valve must be determined by considering both the starting torque and the braking torque. If the pressures required for both are different, the pressure must be unified to an appropriate value. Settings are being made.

For this reason, there are disadvantages such as smooth braking but poor acceleration when starting, or quick starting but shock during braking. The disadvantage is that it takes a long time to operate.

The present invention aims to improve the above-mentioned drawbacks by making it possible to set the starting pressure and braking pressure separately in one relief valve, so that smooth, agile, and agile turning can be achieved. The aim is to realize a swing drive/brake circuit.

First, the configuration of an embodiment of the present invention shown in the drawings will be explained.

In this embodiment, a hydraulic pump king oil tank 2, a directional switching valve 3, a counterbalance valve 4, a relief valve 8.9,
In a normal swing drive/brake circuit composed of a swing motor 5 and a swing body 6, a first... Second pipe line 10b, 10a
and the directional control valve 3 is in the first position in the neutral position. Second
The pipes 10b and 10a are connected to the tank 2, and in the operating position, the oil discharged from the hydraulic pump 1 is transferred to the first and second pipes 10b and 1.
0a, and the directional switching valve 3
When the counterbalance valve 4 is switched by the first
．． Second conduit 10b.

10a, respectively communicating with the third. Fourth pipe line 10d
, 10C are respectively connected to the swing motors 5, and the first and second valves constituting the counter balance valve and the brake valve.
Relief valves 8 and 9 are valve 8f (9f) and spring 8e, respectively.
(9e) and a spring receiver 8d (9d), and communicates with the valve opening side connection port 8a, 9a and the closing valve when the valve 8f (9f) is moved by pressure oil against the spring Be (9e). It is equipped with side connection ports 8b and 9b, and the spring receiver 8d (
The spring support 8d (9d) is installed so that the pressure receiving area on the 9d) side becomes larger.
) and the inner wall of the cylinder is enlarged to form a cylinder chamber 8g (9g) in which the spring receiver 8d (9d) can slide for a predetermined length,
This cylinder chamber 8g (9g) has a structure in which connection ports gc and 9c for introducing pressure oil to the spring receiver 8d (9d) are provided. Pressure oil introduction connection ports 8c and 9 of the second relief valve 8.9
The first and second pressure oil pipes 7a and 7b are respectively connected to the spool 4a of the counterbalance valve 4 at the neutral position. The second pressure oil pipes 7a, 7b and the first. Second
A first passage 4 communicating with the conduits 10b and 10a is provided, and in the operating position, the first passage 4 communicates with the conduits 10b and 10a. The second pressure oil pipes 7a, 7b and the first.
A second pipe communicating with either of the second pipes 10b and 10a. Third passages 42 and 43 are provided.

Next, the operation of the above configuration will be explained.

When the spool 3a of the directional control valve 3 is operated to the left or right from the rotating stationary state, the second directional control valve 3 connecting the directional control valve 3 and the counterbalance valve 4 is connected. First conduit 10a.

10b is generated, the spool 4a of the counterbalance valve 4 moves to the left or right, and the spool 4a of the counterbalance valve 4 moves to the left or right. Third conduit 10
A differential pressure is generated between C and 10d, and a driving force is generated in the swing motor 5, causing the swing body 6 to rotate.

Pressure control at this time is carried out by the first relief valve 8 or the second relief valve 9, but since these valves have completely the same structure, the first relief valve 8 will be explained below.

When the spool 4a of the counterbalance valve 4 moves to the left or right, a portion of the pressure oil is transferred to the second passage 4° or the third passage.
It flows from the passage 43 through the first pressure oil pipe line 7a to the pressure oil introduction connection port 8C of the first relief valve 8, and is sent to the cylinder chamber 8g.

The spring receiver 8d is moved to the left in the drawing by this pressure oil until it hits the stopper portion 11 and stops.

In this stopped state, the opening pressure of the valve 8f is set, and the third pipe line 1
The upper limit of the differential pressure between 0d and the fourth conduit 10C is set, and therefore the starting torque of the swing motor 5 is determined.

Since the pressure receiving area of the spring receiver 8d is larger than the pressure receiving area on the valve opening side connection port 8a side of the valve 8f, even if a high pressure that causes the valve 8f to open is generated at the connection port 8a, the spring receiver 8d will not be able to maintain the first pressure. Since the same pressure is received through the oil pipe 7a, the set pressure can be maintained without moving to the right.

Next, in order to stop turning, the spool 3a of the directional control valve 3
is returned to neutral, the pipes 10a and 10b are connected to the oil tank 2, and the first. Second conduit 10b.

10 Since there is no differential pressure between a and 4, the counterbalance valve 4
The spool 4a returns to neutral.

At the same time, the first hydraulic line 7a also includes the first passage 4 of the spool 4a,
and 1st. Since it is connected to the oil tank 2 through the second pipes 10b and 10a, the pressure oil in the cylinder chamber 8g that was pressing the spring receiver 8d to the left is removed by the spring 8e, and the spring receiver 8d is pushed to the right end. and in this state, close valve 8.
The valve opening pressure f is set, and the braking torque of the swing motor 5 is determined.

The set pressure during braking is clearly lower than the set pressure during starting.

As described above, in the swing drive/brake circuit according to the present invention,
Since the pressures at startup and braking can be set separately in two-stage reciprocating operations, it is possible to set the optimal startup torque and braking torque, respectively, and therefore good operability can be obtained.

■Smooth and fast turning operations are possible, which has the effect of shortening cycle time.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. 1...Hydraulic pump, 2...Oil tank,
3... Directional switching valve, 4... Counter balance valve, 4a... Its spool, 4...-
...Passage ↓, 42.43...2nd. Third passageway, 5...Swivel motor, 6...Swivel body, 7a, 7b...First and second pipes, 8.
...First relief valve, 8a... Valve opening side connection port, 8b... Valve closing side connection port, 8C...
・Connection port for pressure oil introduction, 8d...Spring receiver, 8e・
...Spring, 8f...Valve, 8g...
・Cylinder chamber, 9...Second relief valve, 9a・
...Valve opening side connection port, 9b... Valve closing side connection port, 9C... Pressure oil introduction connection port, 10 b,
10 a... 1st ° 2nd conduit, 10 d, 1
0 C...3rd. 4th conduit.

Claims (1)

[Claims for Utility Model Registration] The first. The second pipes 10b and 10a are connected, and the directional control valve 3
is the first in the neutral position. The second pipes 10b and 10a are connected to the tank 2, and in the operating position, the oil discharged from the hydraulic pump 1 is transferred to the first pipe.
The structure is such that the discharge is carried out into either the second pipe line 10b or 10a, and the counterbalance valve 4 is controlled by the directional switching valve 3.
When switching the 1st. The third pipes 10b and 10a communicate with the second pipes 10b and 10a, respectively. Fourth pipe line 10d, 10C
are connected to the swing motors 5, respectively, and constitute the counterbalance valve 4 and the brake valve. The second relief valves 8 and 9 are a valve 8f (9f) and a spring 8e (9e), respectively.
) and a spring receiver 8d (9d), and the valve opening side connection port ga communicates with the valve closing side connection port 9a when the valve 8f (9f) is moved against the spring 8e (9e) by pressure oil. Mouth 8b, 9
b, and the spring receiver 8d (9d) and cylinder are arranged so that the pressure receiving area on the spring receiver 8d (9d) side is larger than the pressure receiving area on the valve opening side connection port 8a (9a) side of the valve 8f (9f). The inner wall is enlarged to form a cylinder chamber 8g (9g) in which the spring receiver 8d (9d) can slide for a predetermined length, and a connection for introducing pressure oil to the spring receiver 8d (9d) is formed in this cylinder chamber 8g (9g). The structure has openings Be and gc, and the first and second
The pressure oil introduction connection ports 8C99C of the relief valves 8 and 9 each have a first one. The second pressure oil pipes 7 a and 7 b are connected, and the spool 4 a of the counterbalance valve 4 is connected to the first pressure oil pipe in the neutral position. The second pressure oil pipes 7a, 7b and the first.
A first passage 4 that communicates with the second pipe lines 10b and 10a.
, and in operating position 1, the first . Second pressure oil pipe line 7a. 7b and 1st. Which of the second conduits 10b and 10a communicates with the second. A swing drive/brake circuit for a construction machine including third passages 42 and 43.