JPS5920911B2 - Pilot-controlled pressure limiting valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a pressure limiting valve having an inlet connection 2 and a return connection separated from each other by a spring-loaded valve piston and a pilot valve.

Compared to a direct-side type pressure limiting valve, a pilot-controlled type pressure limiting valve has an effective damping effect.
Less dependence on pressure medium flow.

Known pilot-controlled pressure limiting valves generally have a valve piston and a spring-loaded pilot valve (
For example, see Japanese Patent Publication No. 35-11137).

In this pressure limiting valve, normally the same pressure acts on the inlet side 2 of the valve piston and behind it, and the valve piston is in a position to close the passage from the inlet side to the return side, but there is an abnormality on the inlet side 2 of the valve piston. When a high pressure is applied, this pressure is sensed by the pilot valve and the pilot valve is displaced to release the pressure behind the valve piston, which creates a pressure difference between the inlet and rear sides of the valve piston. is displaced to the open position to communicate the inlet side with the return side.

In this known pilot-operated pressure limiting valve, a large spring must be installed in the chamber communicating with the atmosphere in order to prevent the pilot valve from being displaced by the pressure normally acting behind the valve piston. In addition to this spring, another spring is required to prevent the pressure behind the valve piston from being released.

Therefore, the structure becomes complicated due to these two springs, and the entire device becomes large and requires a large space, especially because of the large indoor spring that communicates with the atmosphere.
The cost will also be higher.

In view of the above, it is an object of the present invention to provide a system that requires only a single spring without requiring a large space, and that can be incorporated into a pump or other hydraulic device at low cost and with little assembly space. The object of the present invention is to obtain a pilot-controlled pressure limiting valve that can perform

According to the invention, this object has a tap-shaped valve piston for controlling the connection between the inlet connection and the return connection, on the front side of which the inlet is introduced in the opening direction so as to bring both said connections into communication. A side pressure is applied to the opening, and an inlet side pressure is applied to the rear side through the throttle hole in the opposite closing direction.
On the other hand, a spring-biased pilot valve provided in association with the valve piston is provided such that the spring biases the valve piston in the closing direction to place it in the closed position, and the valve body of the pilot valve has a cross-sectional size difference. The larger end face and the smaller end face of this valve member, and the larger end face and the introduction connection portion are communicated directly or through a throttle hole, and the pilot valve member is configured as a pilot valve member. A pilot control (such that the dimensional difference between the larger end face and the smaller end face is communicated with the return connection and the spring of the pilot valve is arranged in a pressure chamber closed by the back surface of the pilot valve) This is achieved by a pressure limiting valve.

This configuration of the invention makes it possible to provide only one spring for biasing the pilot valve, which also biases the closing device of the valve piston. This not only simplifies the structure, but also makes the overall device smaller and cheaper.

Since this single spring is housed in a pressure chamber that is not exposed to the outside air, its lifespan is extended, and in combination with the valve piston shape, a compact structure is achieved.

The special connection between the pilot valve body and the return connection with different dimensions then makes it possible to use the single spring described above.

Additionally, some embodiments of the present invention provide a pressure limiting valve that is easy to manufacture by constructing the pilot valve from a few simple components.

Further, according to another embodiment of the present invention, a pressure limiting valve is provided which is more reliable in maintaining a sealed state when the inlet connection and the return connection are not in communication.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a valve piston that acts as a pressure sensing means, and is provided inside a casing 2 so as to be freely slidable in the axial direction.

The housing 2 has an inlet connection 4 and a return connection 5 which communicate with the front end face 3 of the valve piston 1 .

A compression spring 6 is inserted into the spring chamber T on the side opposite the front end side 3 of the valve piston.

A pilot valve 8 is provided inside the valve piston 1,
This pilot valve is a stepped valve pressed by a compression spring 6 and has a stepped piston 9.

The throttle bore 10 of the stepped piston 9 connects the inlet connection 4 to the spring chamber T and thus provides for both equally sized end faces of the valve piston 1 and unequal sized end faces of the stepped piston 9. are under the same pressure.

The step or lid surface 11 between the end faces of the stepped piston 9 is connected to the return connection 5 by a transverse bore 12 formed inside the valve piston 1 .

In the neutral position of the valve shown in FIG. 1, the stepped piston 9 is held in the position shown by the compression spring 6, and the valve piston 1 is still held in the position shown.

When the pressure at the introduction connection 4 rises to a specified value determined by the strength of the compression spring 6 and the size of the lid surface 11,
The stepped piston 9 is displaced from the illustrated position to the right by a force as large as the cover surface 11 acting from the left to the right, and finally the spring chamber 1 is formed in the stepped piston 9. It is connected to the return connection 5 via a limiting edge 13 and a transverse hole 12 .

When the pressure in the spring chamber γ decreases as a result, the pressure on the end face 3 of the valve piston 1 becomes relatively high, and the valve piston 1 is displaced to the right against the force of the spring 6.

Thereby, the inlet connection 4 is directly connected to the return connection 5.

A more practical embodiment based on the principle described above is shown in FIG.

In this embodiment, the stepped piston 9 shown in FIG. 1 is replaced by a simpler piston 14 with a pin-like projection 15 and a ball 16 that rests against the valve seat 11 in the valve piston 201.

These replacement members are easier to manufacture and provide a better sealing effect.

The function of the pilot valve 208 as a stepped valve is achieved because the cross-sectional area of the piston 14 is larger than the cross-sectional area of the valve seat 17.

The cross-sectional area of the piston 14 corresponds to the larger cross-sectional area of the stepped valve, while the cross-sectional area of the valve seat 11 corresponds to the smaller cross-sectional area of the stepped valve.

The ball 16 is connected to a compression spring 20 via a spring seat 18.
6 is pressed against the valve seat 1T of the valve piston 201.

Further, the throttle hole 210 connects the introduction connection portion 4 to the spring chamber 20γ.

Due to the large pressure difference at the valve seat 1γ and the small flow of pressure medium therethrough, very small displacements of the ball 16 and the piston 14 are required for the pilot valve 208 to operate.

This corresponds to the piston 14 in the through hole 19 of the valve piston 201.
This is made possible by sealing the disc 20 made of highly elastic synthetic resin.

This disk 20 is prevented from being displaced in the axial direction within the through hole 19 by applying preload in its radial direction.
Therefore, the pressure in the inlet connection 4 is
00 elasticity is transmitted to the piston 14 of the pilot valve 208 without friction loss.

Generally, the disc 20 has a valve piston 2010 through the bore 19.
The purpose is to hold the piston 14 so that it does not escape from the piston 14.

In case it could occur that the pressure in the return connection 5 is greater than the pressure in the input connection 4, the disk 20 is additionally held, for example by a rolled-up support disk (not shown).

By sealing the through hole 19 with the disk 20, the through hole 19
It is possible to increase the fit tolerance between the piston 14 and the piston 14, and therefore manufacturing is also facilitated.

Since the synthetic resin disk 20 is provided in the through hole 19, no leakage occurs in the piston 14, and a hydraulic lock is prevented, thereby preventing the pilot valve 208 from leaking.
The accuracy of the operation is increased, and at the same time additional grooves for pressure relief in the piston 14 can be eliminated.

The above-mentioned elements are preferably provided within the threaded barrel 21.

The threaded cylinder 21 can be constructed of several separate members and screwed together, except when accurate machining of the passage hole in the casing is required.

This provides easy replaceability of the valve.

Another preferred embodiment of the pressure limiting valve is shown in FIG.

As already mentioned, a very small flow of pressure medium flows through the pilot valve 20B, which results in a very small displacement of the ball 16 and a correspondingly very small opening between the ball 16 and the valve seat 17. A gap is obtained.

Due to this small size, the gap acts like a very fine gap filter, and small foreign particles contained in the pressure medium are filtered out.

This foreign material settles on the sealing edge of the valve seat 11, impairing the sealing of the pilot valve and rendering the closing pressure of the valve piston 201 insufficient.

A filter 22 is therefore provided between the inlet connection 4 and the throttle hole 310, which filter is surrounded by a tube 23.

In order to obtain good filtration action, tight filtering materials are used.

The resulting large pressure drop is not a problem.

This is because the pressure medium flow flowing through the throttle hole 310 is small.

Such filters can also be used in other embodiments.

Unlike the embodiment of FIG. 2, in the piezo valve 308 the ball 16 is replaced by a conical valve body 24.

The conical valve body 24 has a less inclined surface for rocking than the ball. A pin-shaped protrusion 315 is connected to the conical valve body 24, so that the piston 31
Acts as 4 consecutive bearing needles.

In the next embodiment shown in FIG.
The valve seat 411 of No. 4 is formed by a ring 25 fitted into the valve piston 401.

This ring 25 radially defines the smaller cross section of the stepped valve.

The two-part configuration of the valve seat 41γ inside the valve piston 401 allows a very precise manufacturing of the valve seat.

In the embodiment shown in FIG. 5, the larger cross-section of the stepped valve is defined by the piston portion 524 and the smaller cross-section is defined by the piston 514.

The stepped valve pistons 524, 514 are slidable within a ring 525 within the valve piston 501.

A throttle hole 510 is provided in the flow direction at the front of the piwatt valve 508.

On the other hand, both end face portions of the pilot valve 508 communicate with each other through the protruding hole 26, so that the pilot valve 508
The same pressure is acting before and after 08.

Piston portion 524 is sloped from the inside to the outside in this example.

This ensures high reliability even when the valve seat 517 wears out and the opening pressure of the pilot valve 508 decreases accordingly.

FIG. 6 shows an embodiment that is simpler than FIG.

In this embodiment, the integrally stepped piston having piston portion 524 and piston portion 514 is replaced by a ball-shaped portion 624 and a roller or pin-shaped piston 614.

The piston 614 is slidably inserted into the ring 625.

The throttle hole 610 is formed in the throttle cap 27 in front of the pilot valve 608.

The protruding hole 626 is connected to the piston 614 . In addition to serving as a balancing hole for the reservoir of oil leakage in F15 and the valve piston 601, it also serves as a damper hole for the reservoir of the valve piston 601.

A connection hole 28 for a remote control device (not shown) is provided in the spring chamber 60γ.

Remote control of the pressure limiting valve, which can be used for all of the illustrated embodiments, may include remote control of the pressure limiting valve, such as a simple switching valve.
This is done by connecting the spring chamber 601 to a pressure medium container (not shown) via means.

The piston in FIG.
u and a piston γ14b.

In addition, a throttle cap 1 is provided in front of the pilot valve 108.
A throttle hole 710 is provided at 2γ.

In the embodiment shown in FIG. 8, a pipe throat valve 808 is disposed inside the threaded body 821.

Such a configuration is basically realizable for other embodiments as well.

FIG. 9 shows another embodiment of the invention.

901 is a valve piston, and this valve piston is supported slidably in the axial direction within a threaded cylindrical body 921,
In addition, the screw-in cylinder 921 and the cylindrical member 921 are incorporated inside the casing 902 .

The housing 902 has an inlet connection 904 and a return connection 905 leading to the end face 903 of the valve piston 901 .

Spring chamber 90γ on the side opposite the end face 903 of the valve piston
A compression spring 906 is attached to the.

A pilot valve 908 is provided in the spring chamber and is in the form of a stepped valve with a spring seat 928 and biased by a compression spring 906 .

Spring seat 928 has valve seat 917 and compression spring 90
6 to the ball 929.

The ball 929 is connected to the screw-in cylinder 9210 and the cylindrical projection 93
It is supported by the protrusion 930 so as not to close the hole 931 inside the 0.

A chamber 932 is formed between the spring seat 928, the ball 929, and the protrusion 930, and this chamber is isolated from the spring chamber 901 by an annular plate 933j6 and a sealing ring 934, and is connected to the spring chamber 901 through the hole 931. It is always in communication with the return connection 905.

The throttle hole 910 communicates the inlet connection 904 with the spring chamber 907, so that the same pressure acts on both end faces 935 of the spring seat formed by the outer periphery of the spring seat 928.

a surface portion 936 serving for actuation of the pilot valve 908;
931, on the one hand, due to the area difference between the annular surface 938 formed by the end surface 935S and the valve seat 917, and on the other hand, due to the area difference of the annular surface 9390 defined by the end surface 935 and the outer periphery of the cylindrical projection 930. configured.

Pilot valve 908 remains closed until the force exerted by the inlet pressure on differently sized cross-sectional portions 936, 937 overcomes the force of compression spring 906.

The spring seat 928 remains in contact with the ball 929.

When the introduction force exceeds the specified pressure, the spring seat 928, together with its valve seat 91γ, separates from the ball 929, and the spring chamber 901 is connected to the return connection 905.

This causes the pressure in the spring chamber 907 to dissipate and the valve piston 901 to slide against the force of the compression spring 906 due to the pressure in the inlet connection 904 .

Introductory connection 904 will communicate with return connection 905 .

This embodiment has the advantage that the pilot valve can be constructed from components that are easily manufactured.

The unique configuration of the spring seat ensures the action of a compression spring, resulting in stable balance and a favorable sealing effect.

In the embodiment shown in FIG.
They are both integrated into the casing 1002.

The casing has an inlet connection 1004'j6 leading to the end face 1003 of the valve piston 1001 and a return connection 100.
5.

The compression/'f, warp 1006 is provided in the spring chamber 1001 on the side opposite to the end face 1003.

A pilot valve 1008 serving as a stepped valve is provided within the spring chamber 1007 and is operated by a compression spring 1006 .

Various types of stepped valves shown in the previously described embodiments can also be used.

The opening and closing part between the inlet connection 1004 and the return connection 1005 is formed as a conical valve seat 1040 .

Here, a cylindrical member 1041 is firmly fixed to a screw-in cylinder 1021, and a conical surface 1042 is provided on this member.

A sealing edge 1043 on the valve piston 1001 cooperates with a conical surface 1042.

The opening and closing part between the spring chamber 1001 and the return connection 1005 is provided with an elastic sealing ring 1044 which is held in the annular groove of the valve piston 1001 and which is held within the cylindrical inner surface 1045 of the cylindrical member 1041. is pressed against.

The force of compression spring 1006 normally forces valve piston 1001 against conical surface 1042.

However, especially in the case of assembly for a small assembly space, the compression spring 1006 is limited in its built-in size.
cannot exert the necessary sealing force.

Therefore, in the third modified embodiment shown in FIG. 11, the valve piston 1101 is constructed as a stepped valve.

In this example, the diameter of the conical valve seat 1140 is the diameter of the cylindrical inner surface 11.
45 in diameter.

This creates working piston surfaces of different sizes, whereby the valve piston 1101 is subjected to an additional force acting in the closing direction due to the inlet pressure.

According to this embodiment, the sealing effect of the pressure limiting valve is improved by the conical seat surface and the differently sized valve piston surface.

As described above with respect to the embodiments, in the pressure limiting valve of the present invention, the compression spring force of the pilot valve increases as the displacement of the valve piston increases, compared to the conventional pressure limiting valve that is pilot controlled. To increase.

Therefore, depending on the magnitude of the spring constant of the compression spring, it is possible to have a characteristic curve that increases with the regulating flow rate.

This increase is freely selectable by the dimensional window of the compression spring and the size of the open cross section of the pressure sensing means formed by the valve piston.

This feature is extremely advantageous for the dynamic operation of the pressure limiting valve.

This is because this feature gives the closed control loop a reactive character.

This makes it possible to suppress vibrations very effectively without special damping means.

Another advantage of the pressure limiting valve of the invention is that it is simplified and compacted by the omission of the second spring and special connecting passages.

The present invention can be implemented in the following manner.

(1) In the pressure limiting valve according to the claims 8, the larger cross-sectional part of the stepped valve is connected to the inlet connection 4;
The smaller cross section of the stepped valve is the spring chamber 7, 207, 30
7,607, the pressure spring 6,206,306 rests on the smaller cross-section of the stepped valve.

(2. In the pressure limiting valve described in the claims, the larger cross section of the stepped valve has a throttle hole of 510° and 610.7°.
10 to the inlet connection 4, the smaller cross-sectional part of the stepped valve is a spring chamber γ.

20γ, 307, 607 directly.

(3) In the pressure limiting valve according to item 1 or 2, the larger and smaller cross-sectional portions of the stepped valve are respectively constituted by pistons 714a and γ14b.

(4) In the pressure limiting valve according to paragraph 1 or 2, the larger cross section of the stepped valve is the piston 14.314.
Therefore, the smaller cross-sectional portion is the seat valve 16, 1γ, 24,
411 and 424.

(5) In the pressure limiting valve according to item 1 or 2, the larger cross-sectional portion of the stepped valve is the seat valve 51γ.

524,624, the smaller cross-sectional part is constituted by the pistons 514, 614.

(6) In the pressure limiting valve according to the claims and any of the preceding clauses, the smaller cross-sectional portion of the stepped valve comprises a ring 25,525° that is replaceable within the valve piston 401,501°601. 625 in the radial direction.

(7) In the pressure limiting valve described in the claims and each of the above items, the larger hole 19 of the stepped valve is closed by a synthetic resin disk 20.

(8) In the pressure limiting valve described in the claims and each of the above items, the filter 22 is provided between the introduction connection portion 4 and the throttle hole 310.

(9) In the pressure limiting valve described in the claims and each of the above items, the pressure limiting valve is provided within the threaded cylinder 21.

00) In the pressure limiting valve described in the claim window and each of the above items, the valve piston 1, 201.301°401
．． Pilot valves are provided in 501 and 601.

αυ In the pressure limiting valve described in the claims and each of the above items, the pilot valve 808 has a threaded cylindrical body 821.
It is located inside.

(12. In the pressure limiting valve described in the claims and each of the above items, the spring chamber 60γ is connected to the connection hole 28 for the remote side
It is connected to the.

03) In the claimed pressure limiting valve, the stepped valve has a spring seat 928 with a valve seat 91γ, and the smaller cross-sectional portion 936 of the stepped valve has a spring seat 928 with a valve seat 91γ.
an end face 935 bounded by the outer periphery of the valve seat 9;
11 , while the larger cross-sectional portion 93γ of the stepped valve is defined by the difference between the annular surfaces 938 and 935 , which are bounded by the ends) and a cylindrical projection 930 projecting inwardly of the spring seat 928 . and an annular surface 939 bounded by the outer periphery of.

04) In the pressure limiting valve according to the claims, the valve pistons 1001, 1101 between the inlet connection 1004 and the return connection 10050 have conical valve seats 1040,
1140 and between the spring chamber 100γ in the valve piston 1001.1101 and the return connection 1005 is a cylindrical sealing part 1045 with an elastic sealing ring 1044.
1145 is provided.

(15) In the pressure side valve described in item 14, the conical valve seat 1140 has a smaller diameter than the cylindrical sealing portion 1145.

[Brief explanation of drawings]

FIG. 1 is a principle sectional view of one embodiment of the pressure limiting valve of the present invention, FIGS. 2 to 8 are sectional views showing various embodiments of the pressure limiting valve of the present invention, and FIG. FIG. 10 is a sectional view showing still another embodiment of the invention, and FIG. 11 is a partial sectional view showing a modified embodiment of FIG. 10. 1.201,401,501,601,9 (N. 1001.1101... Valve piston, 4, 9
04. 1004...Introduction connection part, 5,905,100
5... Return connection, 8.208.308.50
8. 608.708.808.908.1008...
・Pilot valve, 10,210,310,510°61
0.710,910...Aperture hole, 11...
...Lid surface.

Claims (1)

[Scope of Claims] 1. Cup-shaped valve piston 1,201°401 that controls the connection between the inlet connection 4'j6 and the return connection 50.
．． 501, 601, 901, and 1001, and an inlet side pressure acts on the bottom outer surface of the tip forming the front surface in the opening direction so as to communicate the two connecting portions, and a valve piston acts on the back surface in the opposite closing direction. A spring-biased pilot valve 8, 208 provided in conjunction with the valve piston is configured to act on the inlet pressure fed through the throttle hole of
308.508.708.808 is provided such that the spring biases the valve piston in the closing direction to place it in the closed position, and the valve body of the pilot valve is configured as a valve body with different cross-sectional dimensions. , the larger end face and the smaller end face of this valve body, and the larger end face and the introduction connection portion 4.
is direct or aperture hole 10, 210, 310, 510
, 610° γ10, the dimensional difference 11 of the larger and smaller end faces of the pilot valve body is in communication with the return connection 5, and the springs 6, 206, of the pilot valve 306 is a pressure chamber 7° 207.307,60 closed by the back surface of the pilot valve.
7. A pilot-controlled pressure limiting valve, characterized in that it is provided in a chamber of 7. 2 The pilot valve body has a spring seat 9 having a valve seat 917
28, the smaller end face of the pilot valve body is formed by the difference between its end face 935 formed by the outer periphery of the spring seat 928 and the circular surface 938 formed by the valve seat 91γ, while the pilot valve body Claim 1: The larger end surface of the valve body is formed by the difference between the end surface 935 and a circular surface 939 formed by the outer circumference of the cylindrical projection BO protruding inwardly from the spring seat 928. Pilot antibacterial pressure limiting valve as described in Section. 3 The valve piston 1001.1101 is connected to the inlet connection 10
04 and the return connection 1005 with a conical valve seat 1040
, 1140, and a pressure chamber 10 inside the valve piston.
01 and the return connection 10050, an elastic sealing ring 10
A pilot-operated pressure limiting valve as claimed in claim 1 having cylindrical sealing portions 1045, 1145 with 44.