NL2001471C2 - Electromagnet valve, has second seat for sealing ring formed by annular edge protruding from wall of groove in which ring is held - Google Patents

Abstract

A second seat (30) is provided for the sealing ring (20) and is formed by an annular edge which protrudes from a groove wall and projects inward into the ring. The valve comprises a housing with an axial bore which is flow-connected to at least one inlet port and an outlet port; a valve element (12-14) which can be moved back and forth in the bore in the axial direction; at least one annular groove with a groove wall which forms part of the housing or valve element; and a sealing ring made of an elastomeric material which is received in the groove in a form-fitting manner. The valve element can be moved between a closed position in which the ring rests against a first seat (26) so as to produce a seal and an open position in which a throughflow opening is left free between the ring and first seat.

Description

P29328NL00 / RR

Brief indication: Electromagnetic valve with groove provided with an upstanding seat edge for securing a sealing element.

The invention relates to an electromagnetic valve for regulating a medium flow, in particular to a so-called balanced 3-way electromagnetic valve. Balanced means that the force required for opening or closing the valve is independent of the fluid pressure. The fluid pressure can hereby end up at any inlet or outlet port of the valve, without this fluid pressure affecting the force required for opening or closing the valve. Balance is hereby achieved by providing opposite surfaces of equally large upstream surfaces of a sealing area to a movable valve element of the valve which are exposed to the medium.

Many variants of solenoid valves are known from the prior art.

See, for example, U.S. Pat. No. 2,971,090 and U.S. Pat. No. 3,077,207. The electromagnetic valves disclosed herein each comprise three inlet resp. outlet ports and a valve member movable back and forth in an axial bore of a housing. The valve element and / or the housing are provided with circumferential grooves in which O-rings are accommodated. Furthermore, seats are provided against which the O-rings can come to lie sealingly depending on the position of the valve element.

A disadvantage here is that the seal sometimes leaves something to be desired. For example, it may happen that in a closed position, medium still leaks away around the O-ring. This can be further enhanced by the fact that the medium exerts pressure that extends to between the groove wall and the Ο-ring. Particularly at high pressures, this will result in the O-ring being slightly pushed out of its peripheral groove, or even completely pop out of the groove. Temperature fluctuations, dimensional tolerances, aging and wear of the relevant parts can lead to a greater risk of leakage.

For a large number of years, the applicant has been selling a balanced 3-way direct-acting solenoid valve of the ASCO series 327. This type of solenoid valve is used, for example, to control large butterfly valves and ball valves used in the process industry and the petrochemical industry . Due to varying environmental influences and process conditions such as temperature and medium used, the seals used therein must be able to withstand a wide range of conditions in order to provide a reliable seal at a certain required pressure. To this end, a choice can be made from different types of elastomeric sealing materials, each with its own specific properties, such as temperature properties and chemical resistance. The current construction comprises O-rings which are arranged in a tightly closed position in correspondingly recessed grooves in a holder of the valve element.

A disadvantage is that at higher pressures, for example between 14 and 20 bar, the O-rings tend to roll out of their grooves. This tendency is strongly dependent on the fit of the O-ring in the groove, the temperature of the medium and the hardness of the elastomeric material of the O-ring. An attempt has been made to overcome this problem by starting to manufacture O-rings with a higher dimensional tolerance so that they could better be tightly accommodated in the associated grooves. Particularly when using expensive sealing materials for aggressive media, however, this quickly led to considerably higher costs. Attempts have also been made to use vulcanized sealing materials directly in the grooves. Vulcanization, however, is an inaccurate process and leads to a harder sealing element because it becomes completely stuck in the groove.

This, in turn, has to be overcome with an adjustment of the stroke stroke of the valve element, which has a negative impact on the required magnetic forces, resp. on the degree of sealing to be obtained.

It is an object of the present invention to at least partially overcome the aforementioned disadvantages or to provide a useful alternative. In particular, the invention has for its object to provide an electromagnetic valve with a higher degree of sealing and which is suitable for higher pressures.

This object is achieved by an electromagnetic valve according to claim 1. The valve herein comprises a housing with an axial bore which is in flow communication with at least one inlet and an outlet port. A valve element is movable back and forth in the bore in the axial direction. The valve comprises an annular groove that is bounded by a groove wall that forms part of the housing or the valve element. An annular sealing element of an elastomeric material is formed in the groove to form a form. The valve element is movable between a closed position in which the sealing element abuts in a sealing manner against a first seat and an open position in which a flow opening is released between the sealing element and the first seat. According to the inventive concept, a second seat is provided which is in the form of an annular edge protruding from the groove wall and protruding into the sealing element. When placed in the groove, the sealing element should preferably deform somewhat elastically around the second seat in order to be able to take a good place in the groove.

The second seat advantageously forms an additional seat which, together with the first seat, prevents the sealing element from being wholly or partially pushed out of the groove under the influence of the prevailing medium pressure. Another advantage is that in the closed position of the valve, the sealing element now rests against both the second seat and the first seat. The extra seat provides a mechanical locking and an additional sealing edge for the sealing element. All this guarantees a reliable seal in the closed position, even if the fit of the sealing element 5 has a certain amount of play in the groove, for example as a result of temperature fluctuations, dimensional tolerances, aging and / or wear of the relevant parts. Small differences in volume of the annular sealing element are now less relevant and can be easily and simply absorbed by the second seat. The same applies to any unevenness in the groove wall. The construction thus obtained has proved to be highly resistant at higher pressures. Pressures up to more than 25 bar are now possible and still produce good results. Special O-rings or other types of sealing elements with high dimensional tolerances no longer have to be advantageously manufactured.

In a special embodiment the second seat is provided at a position along the groove wall which is situated at a distance from the free peripheral edges thereof, for instance at a distance of at least a few millimeters, and / or in a middle position between these free peripheral edges. More specifically, the second seat is provided at a position along the groove wall that extends at an angle of 40-50 degrees with respect to the axial direction of the housing. These measures individually or in combination ensure that the second seat can protrude sufficiently into the sealing element to fulfill its function.

In a preferred embodiment, the sealing element is an O-ring, and the groove wall defines an at least semicircular complementary cross section along which the second seat is provided. O-rings are inexpensive, reliable and can be manufactured easily and accurately from all kinds of elastomers. They are also suitable for both high and low pressures.

The second seat advantageously extends continuously in circumferential direction along the groove wall. The second seat then forms, as it were, a continuous threshold against a pressure wave entering between the groove wall and the sealing element. The pressure wave 30 is hereby advantageously interrupted and can then no longer exert pressure on the sealing element along the entire groove wall.

In one embodiment, the second seat is integrally molded on the groove wall. Thus, it is possible to manufacture the second seat in one machining run simultaneously with the groove in a turning operation with the aid of a suitably shaped insertion chisel.

The invention is preferably carried out in an electromagnetic valve of the above-mentioned direct-acting balanced 3-way type. The valve is herein provided with two grooves with seat edge which are opposed in the axial direction and a sealing element received therein. This makes it advantageously possible to operate this type of valve with a very low power and at the same time to obtain a very high degree of sealing.

Further preferred embodiments are defined in the subclaims.

5

The invention will be further elucidated with reference to the accompanying drawing, in which:

FIG. 1 is a schematic sectional view of a preferred embodiment of a 3-way solenoid valve according to the invention in a released position; FIG. 2 is a view similar to FIG. 1 in an engaged position;

FIG. 3 is a partial view of FIG. 1 on an enlarged scale;

FIG. 4 is a cut-away perspective view of the holder in FIG. 1; and

FIG. 5 is a sectional view of the holder in FIG. 4.

The electromagnetic valve is indicated in its entirety in Figures 1 and 2 by the reference numeral 1. The valve 1 comprises three inlet and outlet heads respectively. outlet ports 2, 3 and 4 which are provided in a housing 5 and connect there to an axial bore 7. A bore element 8 is provided which can be moved up and down in the axial direction by controlling an electromagnet 10. FIG. 1 shows the position in which the magnet 10 is switched off and the valve element 8 is pressed down under the influence of springs 11a, 11b. FIG. 2 shows the position in which the magnet 10 is switched on and the valve element 8 has been pulled up under the influence of the magnetic forces.

The valve element 8 comprises a core 12, a holder 13 pushed thereon and a sleeve 14 pushed thereon. Together, the core 12, the holder 13 and the sleeve 14 define two annular grooves in which O-rings 19, 20 are received. Each annular groove thus formed has an at least partially circular segment-shaped cross-section and encloses with its groove walls more than half the cross-section of the relevant O-ring 19, 20, in particular more than three-quarters of the cross-section, while leaving axially oriented openings 22 free. Each O-ring 19, 20 is thereby retained in its groove in a form-locked manner. The groove walls of the upper groove are formed on the one hand by the holder 13 and on the other hand by the core 12. A free peripheral edge projecting radially outwards is provided on the core 12. The groove walls of the lower groove are formed on the one hand by the holder 13 and on the other hand by the bush 14. The bush 14 is provided with a free peripheral edge protruding radially outwards. This edge is obtained, for example, by slightly flipping the free end of the sleeve 14 together with a part of the free end of the core 12 or not.

- 5 -

The housing 5 is provided with two first seats 25, 26 which are slightly edged here and which are positioned opposite the respective O-rings 19, 20. Depending on the position of the valve 1, either the O-ring 19 can be sealed lie against its associated seat 25 (Fig. 2) or the O-ring 20 to be sealingly against its associated seat 26 (Fig. 1).

As can be clearly seen in Fig. 3, a second seat 30 is integrally molded on the holder 13 at a central position at a distance from the free peripheral edges of the groove. This seat 30 is designed as an annular edge protruding from the groove wall and protruding such into the O-ring 20 so that it deforms slightly as a result.

The holder 13 is of symmetrical design, which is advantageous for manufacture and assembly. Both groove parts provided in the holder are herein provided with a seat edge protruding from the groove wall. The groove parts are each provided in one of the two axially directed end faces of the holder 13. The symmetry is clearly seen in Fig. 4. In this Fig. It is also clearly visible that the seat 30 extends continuously along the circumferential direction along the part of the groove wall provided in the holder 13.

The arrangement of the seat edge 30 protruding from the groove wall is preferably such that it is directed at least partially towards the seat 26 in the axial direction. As can be seen in Fig. 5, the seat 30 has a center line extending at an angle of 40-50 degrees, in particular about 45 degrees with respect to the axial direction 50. Furthermore, the seat 30 here has a height of between 0.2-0.4 mm, in particular approximately 0.3 mm. The seat 30 has sloping side walls, in particular side walls that are at an angle of 25-35 degrees, more particularly 30 degrees, with respect to the center line of the seat 30. At its free end, the seat 30 is rounded, in particular with a radius of at most 0.1 mm. The part of the groove wall provided in the holder 13 has a circle segment-shaped cross-section that covers more than 180 degrees and whose center line, like that of the seat 30, extends at an oblique angle to the axial direction. This makes it possible to manufacture the holder 13 including its grooves and seats in a turning process. The holder 13 is, for example, manufactured from a magnetic stainless steel material.

In addition to the embodiment shown, many variants are possible. The invention can thus also be applied in other types of (electromagnetic) valves, for example 2-way valves with only one O-ring provided in a groove with a seat edge. Instead of an O-ring, it is also possible to use other types of sealing elements with differently shaped cross sections. The seat edge protruding from the groove wall can be provided at a different position along it and / or be designed differently, while a plurality of seat edges protruding from the groove wall can also be provided. For example, the part of the groove wall formed by the holder can comprise several seat edges. It is also possible to equip the core and / or the bush with such seat edges.

Thus, according to the invention, a reliably operating electromagnetic valve is provided which can be manufactured inexpensively and which lends itself well to application under difficult conditions.

10

Claims (17)

An electromagnetic valve comprising: - a housing with an axial bore that is in flow communication with at least one inlet and one outlet port; - a valve element that can be moved back and forth in the bore in the axial direction; 5. at least one annular groove that is bounded by a groove wall that forms part of the housing or the valve element; - an annular sealing element of an elastomeric material which is received in the groove in a form-fitting manner; the valve element being movable between a closed position in which the sealing element 10 is sealingly abutting against a first seat and an open position in which a through-flow opening has been left free between the sealing element and the first seat, characterized in that a second seat is provided which is designed as annular edge protruding from the groove wall and protruding inwardly into the sealing element received in the groove. The electromagnetic valve of claim 1, wherein the second seat is provided at a position along the groove wall that is spaced from the free peripheral edges thereof. 3. Electromagnetic valve according to claim 2, wherein the second seat is provided in a middle position between the free peripheral edges of the groove wall. 4. Electromagnetic valve according to any of claims 2-3, wherein the second seat has a center line that extends at an angle of 40-50 degrees with respect to the axial direction of the housing. Electromagnetic valve according to one of the preceding claims, wherein the sealing element is an O-ring, and the groove wall defines an at least semicircular complementary cross section along which the second seat is provided. 30 Electromagnetic valve according to one of the preceding claims, wherein the second seat extends continuously along the groove wall in the circumferential direction. 7. Electromagnetic valve according to any of the preceding claims, wherein the second seat is integrally molded on the groove wall. - 8 - 8. Electromagnetic valve according to claim 7, wherein the second seat is manufactured simultaneously with the groove in a turning operation with the aid of a turning tool. The electromagnetic valve according to any one of the preceding claims, wherein the second seat has a height of between 0.2-0.4 mm. 10. Electromagnetic valve as claimed in any of the foregoing claims, wherein the second seat has sideways sloping away walls, in particular side walls which are at an angle of 25-35 degrees with respect to a center line of the second seat. Electromagnetic valve according to one of the preceding claims, wherein the second seat is rounded at its free end, in particular with a radius of at most 0.1 mm. 12. Electromagnetic valve as claimed in any of the foregoing claims, wherein the groove is provided in an axially directed end of the valve element, and the groove comprises an opening opening in the axial direction. 13. Electromagnetic valve as claimed in any of the foregoing claims, wherein the valve element comprises a core and a holder connected thereto, and wherein the groove is at least partially provided in the holder and the groove wall is at least partially part of the holder. 14. Electromagnetic valve according to claim 13, wherein the groove wall is formed in radial direction 25 inwards by a bush placed between the core and the holder. 15. Electromagnetic valve according to claim 14, wherein the form-fitting of the sealing element in the groove is obtained by an upset wall part of the bush. 16. Electromagnetic valve according to one of the preceding claims, wherein the first and the second seat are directed at least partially towards each other in the axial direction. 17. Electromagnetic valve according to one of the preceding claims, comprising three inlet resp. outlet ports, a second groove with an annular seat edge provided therein and an annular sealing element of an elastomeric material accommodated therein, the grooves each being provided at one of the axially directed end ends of the valve element.