JPH0241643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is provided in a hydraulic circuit for driving an actuator, and when the actuator is stopped from a driving state, the actuator is driven in the opposite direction by the hydraulic pressure due to the inertial load of the actuator. This invention relates to a valve that prevents so-called swinging back.

Conventionally, as this type of swing back prevention valve, the first
The items shown in Figures a and b were found.

In FIG. 1a, 3
is a counterbalance valve, which has a neutral position 3a and switching positions 3b, 3c.On the upstream side of this counterbalance valve 3, a hydraulic pump and a tank are connected via a directional switching valve (not shown), and on the downstream side, a hydraulic pump and a tank are connected via a directional switching valve (not shown). The first circuit 4a is provided with a swing back prevention valve 2 on the side.
and swing back prevention valve 2' (swing back prevention valve 2' is
Since it has the same structure as the swing back prevention valve 2, it will be omitted. ) is connected to the actuator 1 (hydraulic motor) via the second circuit 4b. Note that 5a and 5b are overload valves.

The swing back prevention valve 2 has a valve body 7 fixed to a main body 6 to which a first circuit 4a and a second circuit 4b are connected, and a small diameter inner hole 8 and a large diameter inner hole 9 in the valve body 7. A poppet valve seat 10 having a smaller diameter than the inner hole 9 and a larger diameter than the inner diameter 8 is formed between the inner holes 8 and 9, as shown in FIG. 1b. A valve body 11 is provided which abuts against a poppet valve seat 10 and is slidably fitted into each of the inner diameters 8 and 9. This valve body 1
1 is open to the spring chamber 12 and a valve portion 14 that is constantly brought into contact with the poppet valve seat 10 by a spring 13 provided in the spring chamber 12 to which the second circuit of the main body 6 is connected;
A passage 16 that opens into a chamber 18 and a throttle 17 that is formed on the side of the inner hole 9 of the poppet valve seat 10 and communicates with the passage 16 are provided. It is formed by the hole 8.

In the hydraulic circuit shown in FIG. 1a, the counterbalance valve 3 is switched to the switching position 3c, pressure oil is supplied to the actuator 1 via the second circuit 4b and the swing back prevention valve 2', and the oil from the actuator 1 is flows out to the tank via the first circuit 4a, the swing back prevention valve 2, and the counterbalance valve 3, and the actuator 1 rotates in the direction of the arrow. In a situation where the actuator 1 is rotating in this direction, when the directional control valve is set to the neutral position, the counterbalance valve 3 is switched to the neutral position 3a, and the first circuit 4
a and the second circuit 4b are both cut off, so the inertial load of the actuator 1 causes the first circuit 4a to
oil pressure begins to rise. This oil pressure acts on the overload valve 5a and the piston 11 of the swing back prevention valve 2. When this oil pressure rises to a certain value, the piston 11 of the swing back prevention valve 2 moves in the opposite direction against the spring 13, and the valve part 14 is separated from the poppet valve seat 10, and the first circuit 4a is aperture 1
7 to allow the pressure oil in the first circuit 4a to flow out to the second circuit 4b. However, at this point, the inertial load acting on the actuator 1 is large, so the oil pressure in the first circuit 4a continues to rise.
The overload valve 5a is activated, the hydraulic pressure in the first circuit 4a is controlled by the operation of the overload valve 5a, and a braking force is applied to the actuator 1 by the hydraulic pressure. In this way, the inertial load acting on the actuator 1 is reduced, but the pressure receiving area of the valve body 11 is reduced as shown in FIG.
increases when the poppet leaves the valve seat 10. Therefore, when the oil pressure in the first circuit 4a drops by a certain value from the oil pressure at the time when the valve body 11 starts moving leftward, the valve body 11 It begins to return to the right, but
This return time is the time during which the oil in the chamber 18 is discharged into the passage 16 via the throttle 15. During this time, the first circuit 4a and the second circuit 4b are connected to the diaphragm 17.
Since the connection remains connected, the hydraulic pressure of the first circuit 4a immediately before the actuator 1 stops is lowered to prevent swinging back when the actuator 1 stops, and the piston 11
When the actuator 1 returns to the position shown in FIG. 1b, the first circuit 4a and the second circuit 4b are closed and the actuator 1 stops.

This swing back prevention valve 2 is designed so that the hydraulic pressure of the hydraulic circuit is
It activates when the oil pressure rises to a certain value, and when the oil pressure becomes lower than the oil pressure at the time of activation, it begins to return and completes the return after a certain period of time, thereby reducing the oil pressure just before the actuator stops to a low pressure when the actuator stops. This prevents the swing back of the
The technical means for this purpose is to use a valve body whose pressure-receiving area changes at the start of operation and at the time of return.

In such a hydraulic circuit, when the actuator 1 is started, the pressure in the hydraulic circuit on the supply side reaches the operating pressure of the swing back prevention valve due to the inertial load at the time of starting, so the first circuit 4a and the second circuit 4b are disconnected. A part of the pressurized oil is not supplied to the actuator 1, simulating a loss of pressurized oil, which is disadvantageous.

The technical object of the present invention is to prevent a swing back prevention valve from operating at startup.

A technical means for achieving this technical problem is to provide an inner hole to which the first circuit and the second circuit are connected, in the valve body which is connected to the first circuit and the second circuit, respectively, which are connected to the actuator. A first valve consisting of a check valve and a poppet valve seat arranged in series is slidably fitted into the inner hole, and this first valve is pressed by a spring from the first circuit side, and one end of the first valve is pressed by a spring from the first circuit side. A second valve abutting the poppet valve seat is provided, and the other end of the second valve is
A spring chamber is provided which communicates with the second circuit through a diaphragm.

The swing back prevention valve having such a technical means supplies pressurized oil to the first circuit to drive the actuator, and when the actuator is driven, the first circuit and the second circuit are controlled by the first valve and the check valve. The hydraulic pressure in the second circuit increases due to the inertia load of the actuator, and this hydraulic pressure causes the first valve and the second valve to open respectively. It is moved against a pressing spring. After that, when the hydraulic pressure in the second circuit begins to decrease due to a decrease in the inertial load of the actuator, the first valve and the second valve are pressed by their respective springs and begin to return, but at this time, the return speed of the first valve is By slowing down the return speed of the second valve, the first valve and the second valve are separated, and the second circuit and the first valve are separated.
The circuit is connected to prevent the actuator from swinging back when it is stopped.

Since the present invention has the above-mentioned technical means, it has the following unique effects.

The technical problem of the present invention is as shown in FIG.
The swing back prevention valve 2a has a small diameter portion 11f that is slidably fitted into the small diameter inner hole 8a of the valve body 7a fixed to the main body 6a, and a large diameter portion that is slidably inserted into the large diameter inner hole 9a. Sleeve valve 1 configured with 11e
1a, and this sleeve valve 11a is connected to the spring chamber 12.
A check valve 19a having a throttle 15a is provided in the inner hole 16a of the sleeve valve 11a, the spring chamber 12a is connected to the second circuit 4b, and the first circuit 4a is connected to the inner hole 16a of the sleeve valve 11a. It is configured to be connected to a chamber 20a formed by the holes 8a and 9a and the sleeve valve 11a, and this chamber 20a is connected to the check valve 19a.
This problem can be solved by providing a pressure chamber 18a connected to the upstream side of the spring chamber 12a through a throttle 17a and connected to the spring chamber 12a through a throttle 15a, but the vibration shown in FIG. The return prevention valve 2a prevents the chamber 2 from increasing when the pressure in the first circuit 4a increases.
The oil pressure at 0a also increases. The oil pressure in the chamber 20a is determined by the pressure receiving area of the large diameter portion 11e that is slidably fitted into the large diameter inner hole 9a of the sleeve valve 11a, and the small diameter portion 11f that is slidably fitted into the small diameter inner hole 8a. Since it acts on the difference, the pressing force due to this hydraulic pressure is applied to the spring 13a.
When the spring force is exceeded, the sleeve valve 11a is moved to the left. At this time, the check valve 19a also moves to the left, so that when the oil pressure in the first circuit 4a increases, the connection between the first circuit and the second circuit is cut off. Then, when the oil pressure in the first circuit 4a begins to decrease and its rate of descent reaches a certain value, the check valve 19a moves to the left side due to the pressure difference between before and after the throttle 15a (chamber 18a and spring chamber 12a). Move the first circuit 4a to the chamber 20a, the aperture 17a, and the inner hole 16.
a. By connecting the spring chamber 12a to the second circuit 4b, the drop in the oil pressure in the first circuit 4a is controlled from the chamber 1.
The actuator 1 is prevented from swinging back when the actuator 1 is stopped by performing this for a time determined by the volume of the diaphragm 8a and the pressing force of the throttle 15a and the spring 13a. Therefore, in this swing back prevention valve 2a, the spring 13a has the function of determining the operating setting pressure and operating time of the sleeve valve 11a, so in order to lengthen the operating time, if the pressing force of the spring 13a is reduced, the sleeve There are problems in that the operating set pressure of the actuator 11a decreases, and the force (holding force) that opposes the external force that acts when the actuator 1 is stopped becomes weaker. However, in the present invention, a first valve having a check valve and a poppet valve seat is slidably fitted into the valve body, and a second valve is provided which abuts on the poppet valve seat of the first valve. Since the spring chamber connected to the second circuit via the spring chamber is provided separately from the first valve body, the operating time of the swing back prevention valve can be adjusted without changing the operating setting pressure of the first valve, so that the actuator can be held. This has the effect of keeping the force at a desired level and adjusting the operating time.

Examples according to the present invention will be described below.

In FIG. 3, the swing back prevention valve 2c is
A valve main body 7c is fixed to a main body 6c to which the circuit 4a and the second circuit 4b are connected, and a first valve 11c having a check valve 20c and a poppet valve seat 10c is slid into an inner hole 8c of the valve main body 7c. Insert freely into this first
The valve 11c has a spring chamber 12 connected to the first circuit 4a.
It is constantly pressed to the left by the spring 13c of c. a second valve 19c having a poppet valve 14c that abuts the poppet valve seat 10c of the first valve 11c;
is equipped with a passage 16c equipped with a throttle 15c, and forms a chamber 18c with the valve body 7c, and this chamber 1
It is always pressed to the left by a spring 21c provided at 8c.

In this swing back prevention valve 2c, when pressure oil is supplied to the first circuit 4a in order to start the actuator 1 in the direction of arrow Y, the oil pressure in the first circuit 4a However, since this oil pressure is blocked by the poppet valve seat 14c and the check valve 20c, no outflow from the first circuit 4a to the second circuit 4b occurs.

Next, when the actuator 1 that is being driven in the direction of the arrow Y is stopped, when the first circuit 4a and the second circuit 4b are cut off by the neutral position 3a of the counterbalance valve 3, the inertial load acting on the actuator 1 causes the first circuit to stop. The oil pressure in the second circuit 4b increases and acts to push the first valve 11c to the right. When the pressing force of the hydraulic pressure acting on the first valve 11c exceeds the pressing force of the spring 13c, it moves to the right together with the second valve 19c. Then, by operating the overload valve 5b, the oil pressure in the second circuit 4b is controlled to a constant value, and the actuator 1 is braked by this oil pressure, thereby reducing the inertial load. Due to this decrease in inertial load, the oil pressure in the second circuit 4b begins to decrease, and the first valve body 11c of the swing back prevention valve 2c begins to move to the left due to the pressing force of the spring 13c. 19c is also pressed by the spring 21c and begins to move to the left. Since the moving speed of the second valve 19c is limited by the throttle 15c, the first valve 1
The moving speed becomes slower than that of poppet valve 14c.
is separated from the poppet valve seat 10c, and the second circuit 4b
The first valve 11c, the check valve 20c, and the spring chamber 12
connected to the first circuit 4a via c and the second circuit 4b
The pressure oil is discharged into the first circuit 4a. This outflow time is determined by the throttle 15c of the second valve 19c and the pressing force of the spring 21c. In this way the second
By reducing the oil pressure in the circuit 4b in accordance with the decrease in inertial load, it is possible to prevent the actuator 1 from swinging back when it is stopped. The operating time of the swing back prevention valve is determined by the opening area of the throttle 15c, the pressing force of the spring 21c, and the volume of the spring chamber 18c.
The opening area of c and the pressing force of spring 21c can be determined regardless of the operating pressure of the swing back prevention valve.

[Brief explanation of drawings]

1A and 2 are hydraulic circuit diagrams including a sectional view of a conventional swing back prevention valve, and FIG. 1B is a partially enlarged sectional view of a conventional swing back prevention valve 2. FIG. 3 is a hydraulic circuit diagram including a sectional view of the swing back prevention valve according to the present invention. DESCRIPTION OF SYMBOLS 1... Actuator, 2c... Swing return prevention valve, 3... Counter balance valve, 4a... First circuit, 4b... Second circuit, 6c... Valve body, 7c...
Valve body, 10c... Poppet valve seat, 11c... First valve, 13c... Spring, 15c... Throttle, 16c
...Passage, 18c...Spring chamber, 21c...Spring.

Claims (1)

[Claims] 1. In a hydraulic circuit including a first circuit and a second circuit for supplying and discharging pressure oil to and from an actuator, a valve body is provided between the first circuit and the second circuit, and a valve body is provided between the first circuit and the second circuit. Provide inner holes to which each of the circuits connects,
A first valve having a check valve and a poppet valve seat arranged in series is provided in this inner hole by being pressed by a spring from the first circuit side, and a valve portion is provided which abuts the poppet valve seat of the first valve. A second valve having a passageway opening at one end and the first circuit side of the poppet valve seat and opening at the other end through a throttle, the other end fitting into a spring chamber and being pressed by a spring provided in the spring chamber. A swing back prevention valve with.