WO2009126020A1

WO2009126020A1 - Electromagnet valve with groove, provided with a projecting seat edge, for locking of a sealing element

Info

Publication number: WO2009126020A1
Application number: PCT/NL2009/000075
Authority: WO
Inventors: Jan Van Der Zee; Adriaan Paul Klein Hesselink; Hendrikus Johannes Bialek
Original assignee: Asco Controls B.V.
Priority date: 2008-04-11
Filing date: 2009-03-31
Publication date: 2009-10-15
Also published as: WO2009126020A8; NL2001471C2

Abstract

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

Description

Title in brief: Electromagnet valve with groove, provided with a projecting seat edge, for locking of a sealing element

The invention relates to an electromagnet valve for the regulating of a medium flow, in particular to what is known as a balanced 3-way electromagnet valve. The term "balanced" refers in this case to the fact that the force which is necessary for opening or closing the valve is independent of the medium pressure. The medium pressure can in this case be applied to any desired inlet or outlet port of the valve, without this medium pressure influencing the force which is necessary for opening or closing the valve. Balance is in this case obtained by providing upstream of a sealing region on a movable valve element valve surfaces which are the same size, directed in opposite directions and are exposed to the medium.

Many variants of electromagnet valves are known in the art. See for example US 2,971,090 and US 3,077,207. The electromagnet valves disclosed therein each comprise three inlet and outlet ports respectively and a valve element which can move back and forth therebetween in an axial bore of a housing. The valve element and/or the housing are provided with circumferential grooves wherein O-rings are received. Seats, against which the O-rings can come to lie so as to produce a seal as a function of the position of the valve element, are also provided.

A drawback of this is that the seal in some cases leaves much to be desired. Thus, it can for example occur that in a closed position medium still leaks away around the O-ring. This can be further intensified in that the medium exerts pressure which persists to between the groove wall and the O-ring. In particular at high pressures, this will lead to the O-ring being pressed outward somewhat out of its circumferential groove, or even falling completely out of the groove. Fluctuations in temperature, dimensional tolerances, ageing and wear to the components in question can in this case lead to a greater risk of leakage.

The Applicant has itself sold for a large number of years a balanced 3-way electromagnet valve of the directly-acting type under the ASCO series 327. This type of electromagnet valve is for example used to activate large butterfly valves and ball valves which are used in the processing industry and the petrochemical industry. As a consequence of varying ambient influences and process conditions such as temperature and medium used, the seals applied therein should be resistant to a broad range of conditions in order to be able to provide a reliable seal at a specific required pressure. For this purpose, a selection can be made from various types of elastomeric sealing materials, each having its own specific properties, such as temperature properties and chemical resistance. The current construction comprises O- rings which are received in a tightly closed manner in grooves which are accordingly formed for this purpose in a holder of the valve element.

A drawback is that at excessively elevated pressures, for example between 14 and 20 bar, the O-rings tend to roll outward from their grooves. This tendency is highly 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. Attempts have been made to overcome this problem by starting to produce O-rings having higher dimensional tolerance so that these could be more effectively received in a tightly closing manner in the associated grooves. However, in particular on application of expensive sealing materials for aggressive media, this soon led to much higher costs. Attempts have also been made to use sealing materials vulcanized directly in the grooves. However, vulcanizing is an imprecise process and leads to a harder sealing element as a result of the fact that said sealing element becomes completely fixed in the groove. This needs then to be overcome again by an adaptation of the setting of the stroke of the valve element, and this has a negative impact on the required magnetic forces or on the degree of sealing to be obtained.

The object of the present invention is to at least partly overcome the above-mentioned drawbacks or else to provide a usable alternative. In particular, the object of the invention is to provide an electromagnet valve which has a higher degree of sealing and is suitable for elevated pressures.

This object is achieved by an electromagnet valve according to claim 1. In this case, 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 can be moved back and forth in the bore in the axial direction. The valve comprises an annular groove which is delimited by a groove wall which forms part of the housing or the valve element. An annular sealing element made of an elastomeric material is received in the groove in a form-fitting manner. The valve element is movable between a closed position wherein the sealing element rests against a first seat so as to produce a seal and an open position wherein a throughflow opening is left free between the sealing element and the first seat. In accordance with the idea of the invention, a second seat is provided and is embodied as an annular edge which protrudes from the groove wall and projects inward into the sealing element. The sealing element should, on placement in the groove, preferably elastically deform somewhat around the second seat in order to be able to fit securely in the groove.

It is highly advantageous for the second seat to form an additional seat which, along with the first seat, prevents the sealing element from being wholly or partly pressed outward from 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 both against the second seat and against the first seat. The additional seat provides, as it were, mechanical locking and an additional sealing edge for the sealing element. This all ensures reliable sealing in the closed position, even if the fit of the sealing element in the groove has a certain degree of play, for example as a consequence of fluctuations in temperature, dimensional tolerances, ageing and/or wear to the components in question. Small differences in volume of the annular sealing element now have less effect and can be accommodated effectively and easily by the second seat. The same applies to any unevenness in the groove wall. The construction thus obtained has been found to be highly resistant at elevated pressures. Pressures of up to more than 25 bar are now readily possible and still provide a good result. Advantageously, special O-rings or other types of sealing elements having high dimensional tolerances no longer have to be produced.

In one particular embodiment, the second seat is provided at a position along the groove wall that is positioned at a distance from the free circumferential edges thereof, for example at a distance of at least a few millimetres, and/or in a centrally positioned position between these free circumferential edges. More particularly, the second seat is provided at a position along the groove wall which extends at an angle of 40-50 degrees with respect to the axial direction of the housing. These features, separately or in combination, ensure that the second seat can project sufficiently inward into the sealing element in order to be able to fulfil its function.

In a preferred embodiment, the sealing element is an O-ring, and the groove wall delimits an at least half-round complementary cross section along which the second seat is provided. O- rings are inexpensive, reliable and can be made easily and precisely from all sorts of elastomers. Furthermore, they are suitable for both high and low pressures.

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

In one embodiment, the second seat is moulded integrally onto the groove wall. It is thus possible to produce the second seat in one step together with the groove in a turning operation with the aid of a suitable paring tool.

In particular, the design of the valve is such that the annular edge of the second seat protrudes in-ward at all times into the sealing element. That is to say, both in the closed and in the open position of the valve element, the annular edge presses inward into the sealing element, and the sealing element deforms elastically around this annular edge.

Furthermore, the design of the valve is preferably such that on enclosing of the sealing element in its groove, small open spaces (annular air gaps) are formed on both sides of the contact face between the top of the annular edge and the sealing element elastically deforming therearound. This ensures that even after slight relaxation of the sealing element, the annular edge can still continue to be pressed sufficiently into the sealing element over time.

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

Further preferred embodiments are defined in the sub-claims.

The invention will be described in greater detail with reference to the appended drawings, in which:

Fig. 1 is a schematic view in cross section of a preferred embodiment of a 3-way electromagnet valve according to the invention in a released position; Fig. 2 is a view corresponding to Fig. 1 in a switched-on position;

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

Fig. 4 is an exploded perspective view of the holder in Fig. 1 ;

Fig. 5 is a partial view in cross section of the holder in Fig. 4;

Fig. 6a and b are views corresponding to Fig. 3 of a variant with a sealing element to which medium pressure is applied internally and externally respectively and which is received in a valve element according to the invention; and

Fig. 7a and b are views corresponding to Fig. 6a and b with a sealing element to which medium pressure is applied internally and externally respectively and which is received in a valve element according to the prior art.

In Figures 1 and 2, the electromagnet valve is denoted in its entirety by reference numeral 1.

The valve 1 comprises three inlet and outlet ports 2, 3 and 4 respectively which are provided in a housing 5 and connect there to an axial bore 7. A valve element 8, which can be moved up and down in the axial direction by means of activation of an electromagnet 10, is provided in the bore. Fig. 1 shows in this case the position wherein the magnet 10 is switched off and the coupling element 8 is pressed downward under the influence of springs 11a, 11b. Fig. 2 shows in this case the position wherein the magnet 10 is switched on and the valve element 8 is drawn upward under the influence of the magnetic forces.

The valve element 8 comprises a core 12, a holder 13 slid thereon and a bush 14 slid thereon. Together, the core 12, the holder 13 and the bush 14 delimit two annular grooves wherein O-rings 19, 20 are received. Each annular groove thus formed has an at least partly circle-segmentshaped cross section and encases in this case with its groove walls more than half the cross section of the O-ring 19, 20 in question, in particular more than three quarters of the cross section, while leaving free axially directed openings 22. Each O-ring 19, 20 is as a result secured in its groove in a form-fitting 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 circumferential edge protruding outward in the radial direction is provided on the core 12. In the radial direction inwards, the groove wall is formed by the core 12. The form-fitting of the O-ring 19 in its groove is automatically obtained by sliding during mounting the holder 13 in the axial direction over the core 12 while the O-ring 19 was already placed therebetween.

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 circumferential edge protruding outward in the radial direction. This edge is for example obtained by upsetting somewhat the free end of the bush 14, optionally together with a part of the free end of the core 12. The form-fitting of the O-ring 20 in its groove is in this case automatically obtained by providing during mounting the bush 14 with its free circumferential edge protruding outward in the radial direction while the O-ring 20 was then already present in its groove.

The housing 5 is provided with two first seats 25, 26 which are embodied here in a somewhat sharp-edged manner and which are positioned opposite the respective O-rings 19, 20. Depending on the position of the valve 1 , either the O-ring 19 comes to lie against its associated seat 25 so as to produce a seal (Fig. 2), or the O-ring 20 comes to lie against its associated seat 26 so as to produce a seal (Fig. 1).

As may clearly be seen in Fig. 3, a second seat 30 is formed integrally onto the holder 13 at a centrally positioned position at a distance from the free circumferential edges of the groove. This seat 30 is embodied as an annular edge which protrudes from the groove wall and projects inwardly into the O-ring 20 in such a way that said O-ring deforms somewhat as a consequence thereof. The holder 13 is embodied symmetrically; this is advantageous for production and assembly. Both groove parts provided in the holder are in this case equipped with a seat edge protruding from the groove wall. The groove parts are each provided in one of both axially directed front ends of the holder 13. The symmetry may clearly be seen in Fig. 4. This figure also shows clearly that the seat 30 extends uninterrupted in the circumferential direction along the part of the groove wall that is provided in the holder 13.

The arrangement of the seat edge 30 protruding from the groove wall is preferably such that said seat edge is directed in the axial direction at least partly toward the seat 26. As may be seen in Fig. 5, the seat 30 has an axis which extends at an angle of 40-50 degrees, in particular approx. 45 degrees with respect to the axial direction 50. Furthermore, the seat 30 has in this case a height of from 0.2-0.4 mm, in particular approx. 0.3 mm. The seat 30 has side walls which run off obliquely, in particular side walls standing at an angle of 25-35 degrees, more particularly 30 degrees, with respect to the axis of the seat 30. At its free end, the seat 30 is rounded off, in particular with a radius of at most 0.1 mm. The part of the groove wall that is provided in the holder 13 has a segment of a circle-shaped cross section which covers more than 180 degrees and the axis of which, just like that of the seat 30, extends at an oblique angle with respect to the axial direction. This makes it possible to produce the holder 13, including its grooves and seats, in a turning process. The holder 13 is for example made of a magnetic stainless steel material.

Fig. 6 shows schematically a variant with a one-part valve element 60 wherein a groove is formed containing a protruding seat edge 61. An O-ring 62 is placed in the groove as a sealing element. The O-ring 62 is received in the groove in a form-fitting manner in that the groove encloses the O-ring 62 for more than half of its cross section. The position shown of the valve is the closed position wherein the O-ring 62 rests against a valve seat 63 provided therebelow in the axial direction so as to produce a seal. In the closed position shown, parts of the O-ring 62 that are not delimited by groove walls are located on both sides of the contact face between the O-ring 62 and the valve seat 63.

Fig. 6a shows a state wherein the closed valve is internally fed with pressurized medium. At a sufficiently high pressure, this medium presses against the O-ring 62 so hard that said O- ring comes to lie on the inside somewhat loose from the groove wall in the valve element 60. However, once it has reached the region of the protruding seat edge 61 , the elastic deformation force of the O-ring 62 around the seat edge 61 is advantageously so great that a pressure wave from the pressurized medium is stopped and can no longer ensure that the O- ring 62 still continues to be pressed loose from its groove wall. Fig. 6b shows a state wherein the closed valve is externally fed with pressurized medium. This pressure tries again to pass the sealing abutment of the O-ring 62 in the valve element 60 and presses, at sufficiently high medium pressure, against the O-ring 62 so hard that said pressure now presses on the outside the O-ring 62 loose from its groove wall. Now again, it is the case that a pressure wave from the pressurized medium is advantageously stopped as soon as said pressure starts to arrive in the region of the seat edge 61. Again, the sealing abutment of the O-ring 62 in the valve element 60 is not jeopardized as a result.

By way of comparison, Fig. 7a and b show similar situations to Fig. 6a and b but then without at least one inwardly protruding seat edge according to the invention being provided in the groove. Now, Fig. 7a clearly shows that, at sufficiently high medium pressure from the inside of the valve seat 63, a bulging 70 of the O-ring 62 begins to occur on the outside of the valve seat 63. Fig. 7b shows that, at sufficiently high medium pressure from the outside of the valve seat 63, a bulging 70' of the O-ring 62 begins to occur on the inside of the valve seat 63. In extreme situations, this can lead to medium beginning to leak along the O-ring 62 or to the O-ring 62 even being pressed right out of its groove.

In addition to the embodiment shown, many variants are possible. For instance, the invention can also be used in other sorts of (electromagnet) valves, for example 2-way valves with just one O-ring provided in a groove with a seat edge. Instead of an O-ring, other sorts of sealing elements having differently shaped cross sections can also be used. The seat edge protruding from the groove wall can be provided at a different position therealong and/or be embodied in a different shape, while a plurality of seat edges protruding from the groove wall can also be provided. Thus, for example, the part of the groove wall that is formed by the holder can comprise a plurality of seat edges. It is also possible to equip the core and/or the bush with seat edges of this type.

Thus, the invention provides a reliably operating electromagnet valve which can be produced economically and is suitable for use under difficult conditions.

Claims

C L A I M S

1. Electromagnet valve comprising:

- a housing with an axial bore which is flow-connected to at least one inlet port and an outlet port;

- a valve element which can be moved back and forth in the bore in the axial direction;

- at least one annular groove which is delimited by a groove wall which forms part of the housing or else the valve element;

- an annular sealing element made of an elastomeric material which is received in the groove in a form-fitting manner; the valve element being movable between a closed position wherein the sealing element rests against a first seat so as to produce a seal and an open position wherein a throughflow opening is left free between the sealing element and the first seat, characterized in that a second seat is provided and is embodied as an annular edge which protrudes from the groove wall and projects inward into the sealing element which is received in the groove in a form-fitting manner.

2. Electromagnet valve according to claim 1 , wherein the second seat is provided at a position along the groove wall that is positioned at a distance from the free circumferential edges thereof.

3. Electromagnet valve according to claim 2, wherein the second seat is provided in a centrally positioned position between the free circumferential edges of the groove wall.

4. Electromagnet valve according to one of claims 2-3, wherein the second seat has an axis which extends at an angle of 40-50 degrees with respect to the axial direction of the housing.

5. Electromagnet valve according to one of the preceding claims, wherein the sealing element is an O-ring, and the groove wall delimits an at least half-round complementary cross section along which the second seat is provided.

6. Electromagnet valve according to one of the preceding claims, wherein the second seat extends in the circumferential direction uninterrupted along the groove wall.

7. Electromagnet valve according to one of the preceding claims, wherein the second seat is formed integrally onto the groove wall.

8. Electromagnet valve according to claim 7, wherein the second seat is produced together with the groove in a turning operation with the aid of a turning tool.

9. Electromagnetic valve according to one of the preceding claims, wherein the second seat has a height of from 0.2-0.4 mm.

10. Electromagnet valve according to one of the preceding claims, wherein the second seat has side walls which run off obliquely, in particular side walls standing at an angle of 25- 35 degrees with respect to an axis of the second seat.

11. Electromagnetic valve according to one of the preceding claims, wherein the second seat is rounded off at its free end, in particular with a radius of at most 0.1 mm.

12. Electromagnet valve according to one of the preceding claims, wherein the groove is provided in an axially directed front end of the valve element, and the groove comprises an opening which opens out in the axial direction.

13. Electromagnet valve according to one of the preceding claims, wherein the valve element comprises a core and a holder connected thereto, and wherein the groove is at least partly provided in the holder and the groove wall at least partly forms part of the holder.

14. Electromagnet valve according to claim 13, wherein the groove wall is formed inward in the radial direction by a bush placed between the core and the holder.

15. Electromagnet 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. Electromagnet valve according to one of the preceding claims, wherein the first and the second seat are directed in the axial direction at least partly toward each other.

17. Electromagnet according to one of the preceding claims, comprising three inlet and outlet ports respectively, a second groove with an annular seat edge provided therein and an annular sealing element which is made of an elastomeric material and received therein, wherein the grooves are each provided at one of the axially directed front ends of the valve element.