JPH0241642B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for an actuator to which a large load is connected, such as an actuator for a swivel base of a truck crane.

An actuator to which a large load is connected is subject to the inertial force of the load when the actuator is driven or stopped. Therefore, if the actuator is suddenly driven or stopped, a large impact is generated. A drive circuit for such an actuator is disclosed in Japanese Patent Application Laid-open No. 71760/1983.

This actuator drive circuit has two brake circuits equipped with a pressure control valve with a pilot section between two main circuits that connect the directional control valve and the actuator, and further connects the directional control valve and the actuator. A counterbalance valve is provided between the pressure control valve and the pilot switching valve so that the pilot portion of the pressure control valve can be connected to either the upstream side of the counterbalance valve or between the counterbalance valve and the directional switching valve. It has been established.

According to this circuit, if the pilot section of the pressure control valve is connected to the upstream side of the counterbalance valve in the pilot switching valve, when the actuator is driven by an external force, pressure will be generated on the upstream side of the counterbalance valve. Since the hydraulic pressure acts on the pilot part of the pressure control valve, it increases the set pressure of the brake circuit and prevents the actuator from being driven by external force (external force due to outdoor wind pressure).

In addition, if the pilot part of the pressure control valve is connected between the counterbalance valve and the directional switching valve with a pilot switching valve, when the directional switching valve is operated from the neutral position to the switching position, The hydraulic pressure of the main circuit on the driving side acts on the pilot section of the pressure control valve, increases the set value of the pressure control valve, and drives the actuator to a value corresponding to the operation amount of the directional control valve. When the directional control valve is operated to the neutral position from this driving state, the main circuit is closed by the counterbalance valve, but the pilot section of the pressure control valve is connected to the tank, so the set pressure of the brake circuit becomes low pressure. , resulting in weak braking force. For this reason,
The actuator stops slowly without impact.

Conventional brake circuits with such functions use a directional control valve to apply hydraulic pressure to the main circuit to adjust the braking force to the actuator when stopping the actuator from the driving state.
Reverse lever operation [operation of switching from one switching position to the other switching position beyond the neutral position. ), the set value of the pressure control valve will suddenly rise to a high pressure, and a large braking force will be applied to the actuator, which is dangerous. Therefore, it has become difficult to perform this reverse lever operation. For this reason, it is difficult to control the position of the actuator by adjusting the braking force, and it is difficult to control the inertia force, which varies depending on the size of the load, using the directional control valve, so the stopping position of the actuator cannot be controlled. has.

The present invention solves the above problems, and its technical means is to provide a brake circuit having a pressure control valve with a pilot chamber between two main circuits connecting the directional control valve and the actuator. established,
In an actuator drive circuit configured to supply hydraulic pressure to the pilot chamber of the pressure control valve by operating a directional valve, the pressure control valve is cut at its tip into an inner hole to which the one main circuit is connected. A main valve having a hole in the notch and its sliding portion is slidably fitted into the notch, and the main valve and the inner hole form a pressure chamber and a pilot chamber, and a first valve is provided on the pressure chamber side of the inner hole. a second annular groove is formed on the pilot chamber side, and the first annular groove and the second annular groove are connected to the other main circuit, and the main valve is connected to the pilot chamber side. After the provided spring pushes the pressure chamber toward the first annular groove and the hole in the sliding portion connects the second annular groove and the pilot chamber, the notch at the tip connects the pressure chamber to the first annular groove. the notch increases the amount of connection between the pressure chamber and the first annular groove in accordance with the amount of movement of the main valve, and the hole in the sliding part and the second annular groove It is characterized by a structure that maintains the connection while the main valve is moving.

The present invention having the above technical means is such that when the directional control valve is switched from the neutral position to the switching position,
Since the pilot chamber of the pressure control valve of the brake circuit is connected to the tank, the main valve is moved toward the first annular groove and the second annular groove by the hydraulic pressure generated in one of the high-pressure main circuits. As a result, the pilot chamber of the main valve is connected to the other (low pressure side) main circuit by the hole in the main valve via the second annular groove, and the pressure fluid of the one main circuit is transferred from the pressure chamber to the main valve. It is connected to the other main circuit through the notch and the first annular groove. At this time, since the main valve has moved to the maximum, the connection between the pressure chamber and the first annular groove through the notch in the main valve is at its maximum. At this time, when the reverse lever is operated to control the braking force, pressure oil is supplied from the directional control valve to the pilot chamber of the pressure control valve. A part of this pressure oil is discharged to the other (low pressure side) main circuit through the second annular groove by the hole in the sliding part of the main valve, so the hydraulic pressure in the pilot chamber is supplied to the pilot chamber. When the pressure becomes equal to the oil volume and the oil pressure in the pressure chamber becomes equal, the main valve is moved by the spring, so that the notch in the main valve moves between the pressure chamber and the first annular groove. Throttle and increase the oil pressure in the pressure chamber.

As described above, in the present invention, since the brake force can be controlled by the hydraulic pressure supplied to the pilot chamber, the brake can be applied in response to fluctuations in the load acting on the actuator.

Examples according to the present invention will be described below.

As shown in FIG. 1, the drive circuit of this embodiment includes a pressure fluid source 1 (hereinafter referred to as pump 1),
A pressure fluid circuit 5 having a directional switching valve 4 connected to main circuits 3a and 3b connected to the discharge side of the pump 1 and an actuator 2 (hereinafter referred to as motor 2), and a main circuit of this pressure fluid circuit 5. Between 3a and 3b, there is a brake circuit 9a in which a pressure control valve 7a to which the main circuit 3a and the pilot circuit 6a are connected is connected to the main circuit 3b via a check valve 8a, and a brake circuit 9a that connects the main circuit 3b and the pilot circuit. A brake circuit 9b is provided in which a pressure control valve 7b is connected to the main circuit 3a via a check valve 8b.
b, tank T and the discharge side of pump 1 are check valve 1
0, the configuration includes a switching valve 12 connected via a variable throttle 11. In addition, between the directional control valve 4 of the main circuits 3a, 3b and the brake circuits 9a, 9b, there are a residual pressure valve 13a consisting of check valves 14a, 15a and a throttle 16a, a check valve 14b, 15b, and a throttle 16b. A residual pressure valve 13b consisting of
Check valves 14a, 14 of these residual pressure valves 13a, 13b
b indicates the pressure control valves 7a and 7a of the brake circuits 9a and 9b for the forward flow of the check valves 14a and 14b.
When the pilot circuits 6a and 6b connected to the tank T are connected to the tank T, the pilot circuits 6a and 6b are configured to leave a residual fluid pressure necessary to operate the pressure control valves 7a and 7b.

The directional control valve 4 provided in the pressure fluid circuit 5 is
A switching valve 12 having a neutral position 4a, switching positions 4b, 4c, and an operating lever 4d, and also having a neutral position 12a, switching positions 12b, 12c, are connected in a linked manner. This directional control valve 4 is in the neutral position 4a
, the discharge side of the pump 1 is connected to the tank T and the main circuits 3a and 3b are closed. At this time, the switching valve 12 is also in the neutral position 12a, closing the pilot circuits 6a and 6b. Directional switching valve 4
is operated to the switching position 4b, the main circuits 3a, 3
b are connected to the pump 1 and the tank T, respectively, and at this time, the switching valve 12 also becomes the switching position 12b, and the pilot circuits 6a and 6b of the pressure control valves 7a and 7b of the brake circuits 9a and 9b are connected to the pump 1 and the tank T, respectively. Connecting. Also, the directional control valve 4 is at the switching position 4c.
When operated, the main circuits 3a and 3b are connected to the tank T and the pump 1, respectively, and at this time, the switching valve 12
also becomes the switching position 12c, and the brake circuits 9a, 9b
The pilot circuit 6a of the pressure control valve 7a, 7b,
6b to the tank T and pump 1, respectively.

The brake circuit 9a has a branch circuit 17a branched from the main circuit 3a and connected to the pressure control valve 7a, a pressure control valve 7a, and a check valve 8a, and one end is connected to the main circuit 3b.
The pressure control valve 7a is connected to the pressure control valve 7a via a common circuit 19 at the other end thereof. The brake circuit 9b is also almost the same as above, and is a branch circuit 17.
b, a main circuit 3a having a common circuit 19 and a check valve 8b;
The circuit 18b is connected to the circuit 18b. Note that the common circuit 19 includes branch circuits 19a, 19b, and 20.
a, 20b and connected to pressure control valves 7a, 7b. Note that the pressure control valves 21a and 21b are pressure control valves arranged between the main circuits 3a and 3b and the common circuit 19 for controlling the starting pressure.

Next, the pressure control valve 7a will be described with reference to FIG. 2, but since the pressure control valve 7b has the same structure, a description of the structure will be omitted.

The pressure control valve 7a has a main circuit 3a connected to a branch circuit 17.
an inner hole 27 having annular grooves 25a, 26a to which the pilot circuit 6a is connected and branch circuits 19a, 20a branching from the common circuit 19 are connected;
a, a main valve 32a that is slidably fitted into the inner hole 27a and has a throttle hole 28a, a hole 29a, an inner hole 30a, and a notch 31a, and this main valve 32a.
and a pressure chamber 33a formed by the inner hole 27a, and a pilot chamber 34a in which a spring 35a is tensioned to constantly press the main valve 32a. In addition, 36a is
This is a stopper for the main valve 32a having a throttle hole 37a.

The main valve 32a of this pressure control valve 7a is connected to the main circuit 3.
When the fluid pressure in a acts on the pressure chamber 33a and the pilot circuit 6a is opened to the tank T, and the pushing force due to the fluid pressure exceeds the pushing force of the spring 35a,
Move leftward, cutout 31a and annular groove 25a
After the connection, the hole 29a and the annular groove 26a are connected to form a restriction between the pressure chamber 33a and the branch circuit 19a and between the pilot chamber 34a and the branch circuit 20a, respectively.

In this embodiment, the switching valve 12 is connected to the directional switching valve 4, but the configuration is not limited to this, and the number of ports of the directional switching valve 4 can be increased to It may also have a function.

Next, the operation of this embodiment will be described.

When the directional switching valve 4 is operated to the switching position 4b, the switching valve 12 is also switched to the switching position 12b. The discharge pressure fluid of the pump 1 flows into the motor 2 via the directional switching valve 4 and the main circuit 3a, and the discharge fluid from the motor 2 flows into the main circuit 3b and the residual pressure valve 13.
It flows out to the tank T via the check valve 14b, the throttle 16b, and the directional control valve 4 of b. At this time, the pilot chamber 34a of the pressure control valve 7a of the brake circuit 9a
includes a check valve 10, a variable throttle 11, a switching valve 12,
Since the discharge fluid pressure of the pump 1 is applied via the pilot circuit 6a, the main valve 32a maintains the position shown in FIG. 2.

The pressure control valve 7b of the other brake circuit 9b is
The pilot chamber 34b is connected to the tank T, and fluid pressure due to the residual pressure of the check valve 14b of the residual pressure valve 13b acts on the pressure chamber 33b via the branch circuit 17b. Therefore, the main valve 32b moves from the position shown in FIG. 1 to the rightmost position, and the pressure chamber 33b
A throttle is formed between the pilot chamber 34b and the annular groove 25b, and between the pilot chamber 34b and the annular groove 26b.

In this way, pressurized fluid is supplied to the motor 2, and the fluid pressure within the main circuit 3a increases as shown by curve A shown in FIG. Note that the slope of this curve A is determined by the operating speed of the directional control valve 4 and the load connected to the motor 2.
When the pressure rises to the set value, a part of the fluid pressure in the main circuit 3a is released to the main circuit 3b via the common circuit 19 and the check valve 8a, thereby preventing an abnormal rise in the pressure fluid in the main circuit 3a. . In this way, when the motor 2 is driven by the discharge pressure fluid of the pump 1 and begins to reach a predetermined rotation speed, the influence of inertia becomes smaller, so the fluid pressure in the main circuit 3a decreases as shown in curve B. do.

As described above, when the directional switching valve 4 is switched to the neutral position 4a while the motor 2 is driving, the switching valve 12 is also switched to the neutral position 12a. When the directional control valve 4 switches to the neutral position 4a, both the main circuits 3a and 3b are closed, but since the motor 2 is driven by the inertia of the load, it sucks the fluid in the main circuit 3a and discharges it to the main circuit 3b. do. On the other hand, by switching the switching valve 12 to the neutral position 12a, both the pilot circuits 6a and 6b are closed, but since the pressure control valve 7b is at the rightmost position in FIG. , the pilot chamber 34b is connected to the main circuit 3a via the hole 29b, the annular groove 26b, the branch circuit 20b, the common circuit 19, the check valve 8b, and the circuit 18b. Therefore, the pressure chamber 33 of the pressure control valve 7b
The discharge fluid pressure of the motor 2 flowing into the main valve 3
2b to hold the main valve 32b in the rightmost position in FIG. 1 against the force of the spring 35b. Main valve 32b
When the pressure chamber 33b is held at this position, the pressure chamber 33b is connected to the low-pressure side main circuit 3a through the annular groove 25b, the common circuit 19, and the aperture formed by the notch 31b. Therefore, the oil pressure of the main circuit 3b is controlled to the oil pressure according to the throttle formed by the notch 31b of the pressure control valve 7b. In other words, as shown in characteristic curve d in FIG.
Since the pressure is controlled to a value according to the restriction formed by the notch 31b of the pressure control valve 7b, a braking force due to the hydraulic pressure acts on the motor 2.

The above is a case where the motor 2 is stopped only by the characteristics of the pressure control valve 7b. However, when the load is light or when it is necessary to stop the motor 2 at a predetermined position, the directional control valve 4 is moved to the neutral position. When a rapid switching operation from 4a to switching position 4c, a so-called reverse lever operation, is performed, the discharge pressure fluid of the pump 1 is supplied to the main circuit 3b. When the directional switching valve 4 is operated with the reverse lever in this manner, the switching valve 12 is also switched to the switching position 12c, and the discharge pressure fluid of the pump 1 is transferred to the pilot via the check valve 10, the variable throttle 11, the switching valve 12, and the pilot circuit 6b. It flows into chamber 34b. Therefore, both the pressure fluid in the pressure chamber 33b flowing through the throttle hole 28b of the main valve 32b and the pressure fluid flowing through the pilot circuit 6b flow into the pilot chamber 34b. The pressure oil flowing into the pilot chamber 34b is discharged from the hole 29b to the main circuit 3a via the common circuit 19, but as the amount of oil increases, the pressure oil flowing into the pilot chamber 34
The pressure between the pressure chamber 33b and the pressure chamber 33b becomes smaller, and the main valve 3
2b moves to the left, and the notch 31b narrows the space between the pressure chamber 33b and the annular groove 25b. Therefore, the fluid pressure in the main circuit 3b rises again, as shown by curve H in FIG. In this way, by operating the reverse lever, the braking force applied to the motor 2 can be adjusted.

The above explanation is for the case where the directional switching valve 4 is operated to the switching position 4b, but the pressure control valve 7a operates in the same manner as described above when the directional switching valve 4 is operated to the switching position 4c. The explanation will be omitted.

When the directional control valve 4 is in the neutral position, the motor 2
Even if an external force acts on the main circuit 3a and the pressure becomes high, the pilot circuit 6a of the pressure control valve 7a is closed, so a braking force corresponding to the set pressure of the pressure control valve 21a is applied to the main circuit 3a. do.

As explained above, the present invention has a configuration in which the pilot circuit of the pressure control valve in the brake circuit provided between the main circuits is controlled by the switching valve linked to the directional switching valve, so that the braking force applied to the actuator is can be freely controlled. Therefore, the stop position of the actuator can be controlled as necessary, regardless of the magnitude of the load driven by the actuator.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG.
The figure is a sectional view of the pressure control valve, and FIG. 3 is a characteristic curve diagram. 1... Pressure fluid source, 2... Actuator, 3
a, 3b... Main circuit, 4... Directional switching valve, 5...
Pressure fluid circuit, 6a, 6b...pilot circuit,
7a, 7b...pressure control valve, 8a, 8b...check valve, 9a, 9b...brake circuit, 12...switching valve, 25a, 25b...annular groove (first annular groove),
26a, 26b... annular groove (second annular groove), 27
a, 27b...inner hole, 28a, 28b...diaphragm hole, 29a, 29b...hole, 30a, 30b...
Inner hole, 31a, 31b...notch, 32a, 3
2b...Main valve, 33a, 33b...Pressure chamber, 34
a, 34b...Pilot room.

Claims (1)

[Claims] 1 Connecting the directional control valve and actuator 2
In the actuator drive circuit, a brake circuit having a pressure control valve having a pilot chamber is provided between two main circuits, and hydraulic pressure is supplied to the pilot chamber of the pressure control valve by operation of a directional control valve. In the control valve, a main valve having a notch at its tip and a hole at the sliding part is slidably inserted into the inner hole to which the one main circuit is connected, and the main valve and the inner hole form a pressure chamber. and a pilot chamber, a first annular groove is formed on the pressure chamber side of the inner hole, and a second annular groove is formed on the pilot chamber side,
The first annular groove and the second annular groove are connected to the other main circuit, and the main valve is pressed toward the first annular groove by a spring provided in the pilot chamber, and connects the second annular groove and the pilot chamber, the notch at the tip begins to connect the pressure chamber to the first annular groove, and the amount of connection between the pressure chamber and the first annular groove increases. The drive circuit for an actuator is characterized in that the amount of the movement of the main valve is increased in accordance with the amount of movement of the main valve, and the hole of the sliding part and the second annular part are configured to maintain connection during movement of the main valve.