JPH0112006Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a logic switching circuit, specifically, it has a pump port, a tank port, and two load ports, and each of these ports has a square main port, a side main port, and a back pilot port. The present invention relates to a logic switching circuit in which four first to fourth seat type main valves are connected, and a pilot valve is connected to each of these main valves to enable switching in four directions.

Conventionally, a logic switching circuit configured to be able to switch in four directions using four seat-type main valves and four pilot solenoid valves as described above has already been developed, as shown on page 41 of the September issue of Hydraulic Technology '80. Are known.

As shown in FIG. 5, this logic switching circuit connects the pump port P to the first and second main valves 1 and 2.
The tank port T is connected to the square main port A of the third and fourth main valves 3 and 4, and the tank port T is connected to the side main port B of the third and fourth main valves 3 and 4, respectively.
side main ports B, B, and the third and fourth main valves 3,
Since the four square main ports A and A are connected to the load ports X and Y, respectively, there is a problem in that fluid leaks between the pump port P and the tank port T.

More specifically, since each of the main valves 1 to 4 uses a seat type valve, no leakage occurs at the main valve seat.
Leakage occurs between the rear pilot port F and the side main port B, and each of the main valves 1 to 4
Pilot solenoid valves 10a to 10 provided correspondingly to
The pilot solenoid valves 10a to 10d are connected to the pump port P, so when driving the pump to move the actuator Ac forward or backward, the pilot solenoid valves 10a to 10d are connected to the pump port P. Fluid leaking from the rear pilot port F of the third and fourth main valves 3 and 4 to the side main port B may flow out to the tank port T connected to the side main port B, or may cause the pump to be driven. stop or
In addition, when stopping the operation of actuator Ac, such as performing unload control while the pump is being driven, the first
The fluid leaking from the side main ports B of the second main valves 1 and 2 to the rear pilot port F is transferred to the rear pilot port F from the pilot solenoid valve 10.
There was a problem that the water leaked out to the pump port P, which is connected via ports a and 10b.

Therefore, the present invention was devised in view of the above problems, and the purpose is to change the connection structure of the four first to fourth main valves to the pump port, tank port, and load port, and to With a simple configuration that only uses a check valve, 4-way switching can be performed, and between any adjacent ports, that is, between a tank port and a load port, a pump port and a load port, and a tank port and a pump port. The structure is as follows:
The pump port is provided with a check valve for blocking the flow toward the pump, and the first and second
A side main port of the main valve is connected to the pump port via a connection passage, and a square main port of the third and fourth main valves is connected to the tank port via a connection circuit, and The square main port of the first main valve and the side main port of the third main valve are connected to one load port through a connecting passage, and the square main port of the second main valve and the side main port of the fourth main valve are connected to one load port through a connecting passage. ports are respectively connected to the other load port via a connecting passage, while communicating a rear pilot port of each of the main valves to a pilot passage having the pilot valve,
The pilot passage of the first main valve communicates with one load port, the pilot passage of the second main valve communicates with the other load port, and the third and fourth main valves communicate with each other.
The pilot passages of the main valves are communicated with the tank ports, and the side main ports and rear pilot ports of each of the main valves 1 to 4 are communicated with each other via throttles. Even if there is a leak between the rear pilot port and the side main port, there will be no leak between the adjacent tank port and load port, pump port and load port, or tank port and pump port. I made sure that there was no such thing.

Next, an embodiment of the logic switching circuit of the present invention will be explained based on FIG.

First, in Fig. 1, RB is the main body of the switching circuit, and is equipped with a pump port P, a tank port T, and two load ports X and Y. 4th main valve 1~
4 and four pilot solenoid valves 11 to 14 are connected as described later.

The main valves 1 to 4 and the pilot solenoid valves 11 to 1
4 uses seat-type valves, and specifically, they are constructed as shown in FIG.

Incidentally, FIG. 2 shows the first main valve 1 and the pilot solenoid valve 11 selected from among the main valves 1 to 4 and the pilot solenoid valves 11 to 14.
The second main valve 2 and the pilot solenoid valve 12 have the same structure, and the pilot passages 21, 21 in the third and fourth main valves 3, 4 are connected in parallel with a throttle 41 and a check valve 42, as described later. The same structure is obtained when the structure in which a circuit is interposed and the check valve 43 is connected in parallel to the throttle 24 is not used.

However, the one shown in FIG.
and a pilot solenoid valve 11 are assembled into one valve body 5. The valve body 5 is provided with a valve chamber 5a, a square main port A, and a side main port B. The poppet-shaped main valve element 1a of the main valve 1 is freely movable inside the main valve 1, and a guide 6 is inserted into the inner cavity of the valve element 1a, that is, the inner cavity which becomes the rear pilot port F of the main valve 1. The pilot valve body 11a of the pilot solenoid valve 11 is freely movable, and the plunger 7 is attached to the back of the pilot valve body 11a.
An electromagnet is configured to correspond to the solenoid S, and a spring 8 is provided on the back of the plunger 7, and the pilot valve body 11a and the main valve body 1a are connected to each other.
is urged in the direction of the square main port A.

Further, in the above configuration, a main valve seat 20 is formed in the step between the valve chamber 5a and the square main port A, and a small diameter pilot passage 21 is provided at the top of the main valve body 1a. A pilot seat 22 is formed at the back of the passage 21, and the pilot valve body 11a is inserted through the pilot passage 21.
The secondary side of the main valve 1, that is, the inner cavity of the main valve body 1a which becomes the rear pilot port F of the main valve 1, is formed so as to communicate with the secondary side of the main valve 1, that is, the square main port A. be.

A shoulder is provided at the top of the main valve body 1a, and an annular chamber 23 is formed between the shoulder and the top, and this annular chamber 23 is communicated with the side main port B. A throttle passage 24 is provided on the side surface of the main valve body 1a facing the annular chamber 23, which communicates the annular chamber 23 with the inner cavity of the main valve body 1a.

In FIG. 2, reference numeral 9 denotes a plunger case that houses the plunger 7 and holds the solenoid S, and is screwed onto the valve body 5. Further, this case 9 is screwed and held onto the switching circuit main body RB.

As shown in FIG.
and the load ports X and Y. Next, this connection configuration will be explained.

First, the pump port P connected to the pump PM is provided with a check valve 30 for blocking the flow toward the pump PM, and the pump port P is connected to the pump PM.
are connected to the side main ports B and B of the first and second main valves 1 and 2 among the first to fourth main valves 1 to 4 through connection passages 31 and 32, and the tank TK
The third and fourth tank ports T connected to
Connecting passage 3 connecting square main ports A and A of main valves 3 and 4
3 and 34.

Then, the square main port A of the first main valve 1 and the side main port B of the third main valve 3 are connected to the second main valve 3.
The square main port A of the main valve 2 and the side main port B of the fourth main valve 4 are connected via communication passages 35 and 36, respectively, and these communication passages 35 and 36 are connected via connection passages 37 and 38. It is connected to the load ports X and Y, which are connected to the actuator AC.

In FIG. 1, reference numeral 21 is formed on the main valve body 1a as shown in FIG. 24 is a pilot passage formed in the main valve body 1a, and is a throttle that always allows communication between the rear pilot port F, that is, the inner cavity of the main valve body 1a, and the side main port B. The first and second
The pilot passages 21, 21 of the main valves 1, 2 are connected to the load ports X, Y, and also to the third and fourth main valves 3, 4.
The pilot passages 21, 21 are connected to the tank port T.
and communicate with each of the main valves 1 to 4.
The side main ports B and the rear pilot port F are communicated through the throttles 24, respectively.

Further, in the valve shown in FIG. 1, a parallel circuit with a throttle 41 and a check valve 42 is interposed in the pilot passages 21, 21 of the third and fourth main valves 3, 4, and a parallel circuit with a throttle 41 and a check valve 42 is provided. A check valve 43 that allows flow only from the rear pilot port F to the load ports X and Y is connected in parallel.

With this configuration, when the load ports X and Y become negative pressure, the rear pilot port F is made negative pressure and the pressure is applied against the spring 8, regardless of whether the pilot solenoid valves 13 and 14 are turned on or off. Main valve 3,
4 to enable self-priming of fluid from the tank TK via the tank port T.

In addition, when using the above configuration, the structure becomes complicated if the parallel circuit and check valve 43 are incorporated into the valve body 5 as shown in FIG. 13,
14 is formed separately from the third and fourth main valves 3 and 4, and the pilot passages 21 and 21 are formed by piping, and a parallel circuit of the throttle 41 and the check valve 42 is interposed in this piping. Then, the piping is connected between the rear pilot ports F of the third and fourth main valves 3 and 4 and the pilot solenoid valves 13 and 14, and the throttle 24 and check valve 43 are connected to the piping. These pipes are connected in parallel to the rear pilot ports F of the third and fourth main valves 3 and 4.
and is connected to the connection passage 37.

Therefore, the logic switching circuit having the configuration shown in FIG. 1 can be operated as shown in FIG.
Four-way switching, such as a street symbol, is possible.
In FIG. 3, S ₁ to _{S 4} are pilot solenoid valves 11 to 4 provided corresponding to the first to fourth main valves 1 to 4.
It is a solenoid attached to 14, and the circle mark indicates excitation, and the x mark indicates demagnetization.

When the actuator Ac is moved forward or backward by the four-way switching as described above, for example, when fluid is supplied from the pump port P to the load port X and fluid is discharged from the load port Y to the tank port T, the OFF operation is performed. The rear pilot port F and the side main port B of the third main valve 3 are in communication with the load port X, so the pressure between these ports F and B is the same, and the third main valve 3
Since the main valve body of the pilot solenoid valve 13 is seated on the main valve seat, and the pilot valve body of the pilot solenoid valve 13 is seated on the pilot seat, fluid will not leak from the load port X to the tank port T.

On the other hand, since the connection between the pump port P and the load port Y is cut off by the second main valve 2 and the pilot solenoid valve 12, which are in the OFF operation as described above, fluid leaks from the pump port P to the load port Y. There is no such thing.

Also, stop driving the pump PM, or
When the actuator Ac stops operating, such as when performing unload control while the pump PM is being driven, there is also a Even if this occurs, the check valve 30 is connected to the pump port P.
, there is no leakage from the load ports X and Y to the pump port P, and as mentioned above, the side main ports B of the third and fourth main valves 3 and 4 are
Since the main port A is connected to the load ports X and Y, and the square main port A is connected to the tank port T, there is no leakage from the load ports X and Y to the tank port T.

Further, according to the configuration shown in FIG. 1, for example, when the actuator Ac is moved to the right, an external force acts on the actuator Ac, causing the actuator Ac to move to the right.
When the load port
The third
Since the rear pilot port F of the main valve 3 is in communication, the rear pilot port F of the third main valve 3 also has a negative pressure, and as a result, regardless of the on/off operation of the pilot solenoid valve 13, 3 main valve 3 operates and the third main valve 3 communicates with the tank port T.
The square main port A and the side main port B communicate with each other to suck fluid from the tank TM, and even when the third main valve 3 does not operate, the main port B corresponds to the third main valve 3. The pilot solenoid valve 1 is connected from the tank TM via the pilot passage 21 in which the pilot solenoid valve 13 is interposed.
3. Fluid is sucked from the connection passage 37 via the throttle 41 and check valve 43. The same applies when the actuator Ac moves to the left.

In order to enable self-priming in the configuration shown in FIG.
Although the parallel circuit with the pilot valves 13 and 14 is installed on the rear pilot port F side with respect to the installation position of the pilot valves 13 and 14, it may also be installed on the square main port A side as shown in FIG.

It goes without saying that low viscosity fluids such as water can be handled under high pressure.

As described above, the present invention provides the pump port P with
A check valve 30 is provided to prevent the flow to the pump side, and a passage 3 connecting the side main ports B of the first and second main valves 1 and 2 to the pump port B is provided.
1, 32, and the square main ports A of the third and fourth main valves 3, 4 are connected to the tank port T via connection circuits 33, 34; The square main port A of the valve 1 and the side main port B of the third main valve 3 are connected to one load port X, and the square main port A of the second main valve 2 and the fourth
While connecting the side main port B of the main valve 4 to the other load port Y via the connection passage 38,
The rear pilot port F of each of the main valves 1 to 4 is
The pilot passage 21 of the first main valve 1 is connected to one load port X, and the pilot passage 21 of the second main valve 2 is connected to the other load port Y, communicating with the pilot passage 21 having the pilot valves 11 to 14. The third and fourth main valves 3 and 4 are connected to each other.
The pilot passages 21, 21 of the main valves 1 to 4 are communicated with the tank port T, and the side main ports B of the main valves 1 to 4 and the rear pilot F are communicated via a throttle 24, respectively. Therefore, while switching can be performed in 12 ways, during any switching operation, as well as when moving the actuator forward or backward, stopping the pump drive,
Even when the actuator is driven but unloaded and the actuator stops operating, it has a simple configuration.
Internal leakage occurring between the rear pilot port F and side main port B of each of the main valves 1 to 4, and leakage between adjacent ports due to internal leakage due to the pilot valve, i.e., tank port T and load port. X or Y
This makes it possible to reliably eliminate leaks that occur between the pump port P and the load port X or Y.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing an embodiment of the present invention, Fig. 2 is a sectional view showing an embodiment of the main valve and pilot solenoid valve, Fig. 3 is an explanatory diagram of operation, and Fig. 4 is a diagram showing the third and fourth valves. FIG. 5 is a schematic explanatory diagram showing another embodiment of the main valve, and FIG. 5 is a schematic explanatory diagram showing a conventional example. 1 to 4...first to fourth main valves, 11 to 14...
Pilot valve, 21...Pilot passage, 22...
... Restriction passage, P ... Pump port, T ... Tank port, X, Y ... Load port, A ... Square main port, B ... Side main port, F ... Back pilot port.

Claims (1)

[Scope of utility model registration request] Equipped with a pump port P, a tank port T, and two load ports X, Y, each of these ports P, T,
Four first to fourth seat type main valves 1 to 4 each having a square main port A, a side main port B, and a rear pilot port F are connected to X and Y, and each of these main valves 1 to 4 is connected to 4 each has a seat type pilot valve 1
1 to 14, the logic switching circuit is configured to be switchable in four directions, and the pump port P
A check valve 30 for blocking the flow toward the pump is provided at the pump, and the side main ports B of the first and second main valves 1 and 2 are connected to the pump port P via connection passages 31 and 32. Further, the square main ports A of the third and fourth main valves 3 and 4 are connected to the tank port T via connection circuits 33 and 34, and the square main ports A of the first main valve 1 and The side main port B of the third main valve 3 is connected to one load port X via the connection passage 37, and the square main port A of the second main valve 2 and the side main port of the fourth main valve 4 are connected. B to the other load port Y via the connecting passage 38, while communicating the rear pilot ports F of each of the main valves 1 to 4 to the pilot passage 21 having the pilot valves 11 to 14, The pilot passage 21 of the first main valve 1 is communicated with one load port X, the pilot passage 21 of the second main valve 2 is communicated with the other load port Y, and the third and fourth main valves 3, The pilot passages 21, 21 of No. 4 are communicated with the tank port T, and the side main ports B and the rear pilot ports F of the main valves 1 to 4 are communicated through throttles 24, respectively. A logic switching circuit characterized by: