JPH038431B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a solenoid valve for pilot controlling a main spool for electromagnetic proportional four-way switching in general industrial fluid pressure equipment. The solenoid valve functions as a pilot switching valve with a pressure reducing device.

(Background Art) Several conventional solenoid valves are known.
For example, what is disclosed in Japanese Patent Application Laid-open No. 49-89923 is
A back pressure chamber is provided at both ends of the pilot spool, and cylinder ports A, B and the back pressure chamber are communicated with each other through a passage within the valve body. When the pilot spool is moved by the solenoid, the pressure oil that is reduced in pressure by the variable orifice that partitions the land of the pilot spool and the end of the port hole generates a reduced pressure △P× on the end face A of the pilot spool in the back pressure chamber.
By balancing A and the solenoid force F acting on the pilot spool, a reduced pressure corresponding to the input current is obtained. The maximum suction force, that is, the rated suction force, of such a solenoid valve is generally fixed, so if the maximum value of the reduced pressure, that is, the rated reduced pressure, needs to be changed due to specifications, control flow rate, valve size, etc., the outer diameter of the pilot pool may be changed. This required changing the diameter of the pilot spool hole in the valve body, and it was difficult to make various changes to the latter.

Another known solenoid valve includes a small piston within a pilot spool that generates a force counteracting the solenoid's force F, and communicates the small piston working chamber with a cylinder port. However, in this case, there were drawbacks such as difficulty in machining the pilot spool hole and the risk of damaging the small piston.

(Object of the Invention) The object of the present invention is to provide a pilot solenoid valve equipped with a pressure reducing device for pilot controlling a main spool for electromagnetic proportional four-way switching, which eliminates the drawbacks of conventional products, and which is capable of adjusting the maximum reduced pressure, that is, the rated reduced pressure, as necessary. To provide an inexpensive solenoid valve that can easily change pressure.

(Structure of the Invention) A pressure port P disposed in the valve body and a pair of cylinder ports A, B and tank ports T, T disposed in sequence on both sides of the pressure port P are built in the valve body to close communication. a retainer fitted into the valve body so as to fit with both ends of the spool and its outer periphery to form a back pressure chamber; and a direct current disposed to move the spool through the retainer. Each cylinder port A,
The solenoid valve is characterized in that it has a pilot passage that communicates B with the back pressure chamber adjacent thereto. With this configuration, the pressure-receiving area of the spool that generates back pressure that opposes the force F of the solenoid is the cross-sectional area of both ends of the spool.
By reducing the cross-sectional area of both ends of the spool and correspondingly making the retainer fitting hole smaller, the opposing back pressure can be further reduced, and the corresponding reduced pressure (pressure per unit area) can be further increased. can.
Therefore, the maximum value of reduced pressure, that is, the rated reduced pressure, can be easily changed by simply replacing the spool with a different cross-sectional area at both ends and the retainer in the fitting hole corresponding to this cross-sectional area. Since the valve body of the solenoid valve can be used, and the spool and retainer can be easily and inexpensively processed, it has become possible to provide such a solenoid valve that is inexpensive for both the solenoid valve itself and the modification.

(Description of Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.
It is commonly used as a solenoid valve for direction switching, and has a pressure port P in a circular hole 18 drilled in the axial direction in the valve body 1, and a pair of cylinder ports A, B, and P on both sides of the pressure port P. Tank ports T, T are arranged one after the other, and a spool 2 which fits into a circular hole 18 and has a suitable plurality of well-known lands provides communication and closure between these ports. The above points are well known and will not be explained in detail. Fitted into the valve body 1 are retainers 3, 3' that fit with both ends of the spool 2 and the outer periphery thereof to form back pressure chambers 6, 6'. Further, both sides of the valve body 1 include DC solenoids 4, 4' arranged to move the spool 2 via retainers 3, 3'. Furthermore, within the spool 2, there are pilot passages 7, which communicate the respective cylinder ports A, B and their adjacent back pressure chambers 6, 6'.
7' is drilled. Preferably, spool 2
The land that closes the cylinder ports A and B is the land that closes the pressure port P when the DC solenoids 4 and 4' are energized.
is closed with zero wrap. Solenoid 4 is
A movable element 19 to which a rod 5, which is supported at both ends by ball bearings 14 and 15, is fixed, is pressed rightward during attraction and excitation. The rod 5 and the retainer 3' may be separated from each other when not energized, or may be in contact with each other. Spring 16 and adjustment nut 1
7 is for manually moving the rod 5 when not energized. The above points also apply to the solenoid 4'.

The solenoid valve X is used by being attached to the main valve Y. The main valve Y has a main spool 13 corresponding to the solenoid valve X, a pressure port P', cylinder ports A', B', tank ports T', T', and main back pressure chambers 11, 11'. a pair of springs 12 that return the spool 13 to the neutral position;
12', and the cylinder ports A and B of the solenoid valve
and the main back pressure chambers 11 and 11' are passage 2, respectively.
They are communicated at 0,20'.

Next, to explain the operating state, assume that an input current is now applied to the left solenoid 4. At this time, an attractive force corresponding to the magnitude of the input current is generated, and this force is transmitted to the retainer 6 via the rod 5, causing the spool 2 to move to the right. At this time, the pressure oil in the pressure port P flows out to the cylinder port B, but the pressure flowing out to the port B is transmitted to the back pressure chamber 6' through the passage 7' in the spool, and becomes a force pushing the spool 2 back to the left. Specifically, the pressure in cylinder port B is controlled to be reduced to a pressure commensurate with the solenoid suction force. Note that since the cylinder port A communicates with the tank port T, the pressure of the port A becomes equal to the tank port T pressure. To explain in more detail, when the spool 2 is moved to the right by the suction force of the solenoid, the pressure oil from the pilot passage 7' is delayed and increases the pressure in the back pressure chamber 6', returning the spool 2 to its original position. However, as the pressure in cylinder port B decreases, the spool is moved to the right again and returned again, and as a result, the pressure in cylinder port B and back pressure chamber 6 is reduced to match the suction force of solenoid 4. be put under pressure. and back pressure chamber 6,
The pressure 6' is a pressure with the cross-sectional area of both ends of the spool 2 as the pressure-receiving area, so it can be applied without changing the outer diameter of the land of the spool 2 and the inner diameter of the inner hole 18 in the valve body 1 that fits there. By reducing the cross-sectional area of both ends of the spool 2 and correspondingly reducing the fitting holes of the retainers 3, 3', it is possible to obtain a smaller pressure in the back pressure chambers 6, 6', and the solenoid 4 , 4', a higher vacuum pressure (pressure per unit area) corresponding to the stronger suction force can be obtained. Therefore, spool 2 with different cross-sectional areas at both ends
By simply replacing the retainers 3, 3' with corresponding fitting holes, the maximum value of the reduced pressure, that is, the rated reduced pressure can be easily changed.

The main valve Y is configured to perform large-flow electromagnetic proportional flow control, and the pressure at the cylinder port is led to the main back pressure chamber 11' through a passage 20'.
The other back pressure chamber 11 communicates with the cylinder port A and is equal to the tank port T pressure.
Therefore, the main spool 13 of the main valve moves to the left and is moved to a position where the spring 12 of the back pressure chamber 11 and the reduced pressure of the back pressure chamber 11' are in equilibrium. At this time, the pressure oil in the pressure port P' of the main valve Y flows into the cylinder port A', and this inflow amount is the amount of movement of the main spool, that is, the reduced pressure in the cylinder port B by the solenoid valve X, that is, the input current to the solenoid 4. It will be proportional to the value.

As described above, in this embodiment, the valve body itself can be a standard solenoid valve, and the maximum value of the reduced pressure, that is, the rated reduced pressure, can be easily changed by simply replacing the spool and retainer. Processing the retainer is easy and inexpensive, so
It is possible to provide an inexpensive solenoid valve that allows such changes to be made at low cost.

[Brief explanation of the drawing]

The drawing shows a schematic sectional view showing a state in which a solenoid valve according to an embodiment of the present invention is used together with a main valve. 1... Valve body, 2... Spool, 3, 3'
...Retainer, 4,4'...Solenoid, 6,
6'...back pressure chamber, 7,7'...pilot passage.

Claims (1)

[Claims] 1. A spool 2 built into the valve body to close communication between the pressure port P disposed within the valve body 1 and each pair of cylinder ports A, B and tank ports T, T sequentially disposed on both sides of the pressure port P. and retainers 3, 3' fitted into the valve body 1 so as to fit with both ends of the spool and the outer periphery thereof to form back pressure chambers 6, 6', and the spool 2 via the retainers. The spool 2 includes pilot passages 7, 7' that communicate between each cylinder port A, B and the back pressure chamber adjacent thereto. A solenoid valve featuring: