FR2719647A1 - Valve, in particular vacuum valve. - Google Patents

Abstract

The present invention relates to a valve, in particular a vacuum valve, comprising a valve seat opening provided with a sealing part (12), and a closing and opening member (14) closing in the direction of the part. and moved in a controlled manner. Surfaces (16o, 16u) facing each other and projecting along at least one component perpendicular to the direction of closing movement (K) of the member (14) are connected on the one hand to the valve seat opening , and to the member (14), on the other hand, which surfaces define an air gap, minimum in the closed position, which is crossed by a magnetic field (H) of a magnet device (18). Unlike the force of a spring, the closing force (F) decreases when the stroke (x) of the member (14) increases.

Description

The present invention relates to a valve, in particular a vacuum valve.

  valve, in particular a vacuum valve, comprising a valve seat opening provided with a sealing part, and a closing and opening member closing in the direction of said valve

  sealing part and moved in a controlled manner.

  Whether for vacuum valves which have a closing and opening member formed by a valve stem provided with a valve head, or for spool valves with which a spool is moved in the plane of the plane. opening to be controlled using a valve technique, it is common to control the opening movement using control members able to be remote-controlled, such as pneumatic, hydraulic or electromagnetic members, and to control on the other hand the closing movement by means of a spring control, so that in the event of a power supply failure, for example, the valve passes through

the safe closing position.

  The closing spring must then be dimensioned so that the required valve seat sealing force is generated either along a circular sealing part, for example, located around the valve seat opening, or direction of a linear sealing part, in the case of slide valves, and in the first case, in particular, of the additional forces which are a function of the pressure difference and which act

  in the opening direction must be absorbed.

  Figure 1 shows, using the example of a valve shown schematically, in particular a vacuum valve, comprising a valve stem 1 and a valve head 3, a known valve provided with a closing spring 5 and an opening control 7 acting against the force of said closing spring 5. 9 designates the annular sealing zone, here, and 11 a metal bellows to be provided with vacuum applications, which envelops the control 7 and in particular the closing spring 5 against the vacuum connection V to be opened and closed at

using the valve.

  Mechanical springs always have a force

  booster which increases with the compression stroke.

  This gives, as shown to the right in Figure 1, a spring force acting in the closing direction which increases with the valve seat stroke x. When x = 0, that is to say when the valve is closed, the spring acts with the closing force F1 according to the sealing force required. Although the valve closing springs usually have a relatively flat characteristic curve as far as the construction conditions allow, the spring force acting in the opening direction on the valve head 3, for a normal working stroke s, goes to a value F2 which is generally approximately 20% to 30% higher than the spring force F1 in the closed position ensuring the

  sealing force required in sealing area 9.

  The opening controls 7 must therefore be designed for the force F2 although only the spring force is needed for x = 0, that is to say FI, as the active force essential for the function. This results in drive units 7, and therefore fairly large valves which

  receive high powers.

  If the control unit 7 is designed as an electromagnetic unit, it must also be taken into account that the control current increases in proportion to the square of the force to be exerted, i.e. to the square of the difference

(F2-F1).

  The object of the present invention is to eliminate the drawback mentioned for a valve of the type specified in

  introduction, including a vacuum valve.

  This object is achieved, according to the invention, with a valve of the type specified in the introduction which is characterized in that surfaces facing each other and projecting along at least one component perpendicular to the direction of closing movement of the member are connected at the valve seat opening, on the one hand, and at the member, on the other hand, which surfaces define an air gap, minimum in the closed position, which is crossed by a magnetic field of a magnet device . Thanks to this configuration, a magnetic force is generated in the closing movement direction, which magnetic force, given that in the closed position, the air gap becomes minimal, then becomes maximum and decreases on the contrary during

opening the valve.

  It is thus obtained that the control unit, whether electromagnetic, pneumatic or hydraulic, can offer a smaller construction for the opening of the valve, since such a unit can be designed for a low absorbed power or for low control agent pressures. It just has to be designed for the maximum opposing force, the sealing force

magnetic.

  In addition, the automatic closing function is retained, since the magnetic force closes the valve in

  control power failure.

  Since the known closing springs are relatively long, the construction of the valve of the present invention is shorter. Even failures caused, for example, by a spring break with the known valves controlled by a closing spring, are no longer taken into account since the magnetic force is available practically without defect. Thanks to the fact that the magnetic force conditioned by the field appears in the form of a force distributed along the air gap, an optimal distribution of the sealing pressure is obtained at the sealing part. Unlike a closing spring, the magnetic force reaches its maximum when the air gap is minimal, that is to say in the closed position of the valve. The force-generating construction members, that is to say in particular the air gap, can be provided at any point along the path of the closing and opening member, which allows a great flexibility for the construction of the valve and for the application of the method of the invention to constructions

of existing valves.

  The magnetic force can thus act directly on the valve head, for example, insofar as a device of permanent magnets and / or electromagnets is provided on said valve head or on the valve seat, and o , therefore, the opposing element is made of soft magnetic material. It is also possible to provide the magnet / air gap device along a valve stem or, in the case of a slide valve, along the lateral slide guides. In a preferred embodiment, the device for permanent magnets and / or electromagnets is provided in the region of at least one of the surfaces facing each other.

  previously mentioned, and firmly connected to them.

  The magnetic field is advantageously controlled by a control signal which depends on the distance between the sealing zone of the member and the sealing zone located at the

valve seat level.

  According to another characteristic, the closing and opening member comprises a slide valve of a slide valve and the sealing part is linear. Advantageously, this member comprises a valve stem and a

valve head.

  The invention also proposes that the member acts, just before opening, against a spring member acting in the opening direction. The spring member may be formed by an elastic sealing member provided at the closing and opening member and / or

  valve seat, in the sealing area.

  In a preferred embodiment, a closing spring acts on the member in the closing direction, whereby said member is pushed into the area

magnetic field.

  According to another characteristic of the invention,

  finally, the valve is designed as a vacuum valve.

  The invention will now be described by way of

example using figures.

  Figure 1 is a schematic representation of a known vacuum valve, Figure 2 shows schematically the basic principle of a valve of the invention, Figure 3 shows, from the basic principle of Figure 2, a preferred embodiment of a valve of the invention, with which the closing stroke is controlled by spring until it reaches the closed position, Figure 4 shows, from the basic principle of Figure 2 and possibly according to a construction according to FIG. 3, displacement damping for the valve closing and opening member intended to prevent rebounding, FIG. 5 shows another embodiment of a valve of the invention , represented as in FIGS. 2 to 4, in which the closing force and therefore the sealing force are controlled as a function of the stroke, and FIG. 6 is a partially sectioned representation of an embodiment currently favorite of a

valve of the invention.

  The basic principle of the invention goes first

  be explained with reference to Figures 2 to 5.

  It emerges for those skilled in the art a large number of different possible embodiments, among which a mode currently used will be presented with reference

in Figure 6.

  According to the schematic functional representation of FIG. 2, a valve basically comprises a fixed covering system, usually an envelope 10, provided with a sealing zone 12 towards which an opening and closing member 14 is moved with its zone seal 17 located on the organ side, as indicated by the double arrow K. The control device intended to move the closing and opening member 14, in particular towards the open position, which may consist of an electromagnetic control unit , pneumatic or hydraulic, is not shown in Figures 2 to 5. On the fixed casing 10, on the one hand, and on the movable closure and opening member 14, on the other hand, are provided surfaces 16o and 16u which define an air gap L between them if the direction of displacement K is considered. The surfaces 16 are arranged with at least one component perpendicular to the direction K, and they can be perpendicular to this, as shown, or they can optionally be curved depending on the configuration desired for the air gap. The surfaces facing each other are crossed by a magnetic field H preferably, but not necessarily, static. The magnetic system 18 generating the magnetic field H, as shown in broken lines, is either movably coupled to the member 14, or coupled to the fixed casing 10. The surfaces 16o, 16u traversed by the magnetic field H are defined by the magnetic system 18 itself or by a soft magnetic material, so that the member 14 is moved by the magnetic force F towards the sealing zone 12. The magnetic system 18 preferably consists of a permanent magnet device, but it can also consist of an electromagnet device or a

  combination of permanent magnets and electromagnets.

  If, as in FIG. 1, the stroke of the member 14 from the closed position is called x, for the closing force F from the closed position with x = 0, the decreasing characteristic curve shown is obtained.

qualitatively in Figure 2.

  It is quite possible to move the member 14 over the entire closing stroke, that is to say from the open position with x = P to the closed position with x = 0, to

  using the magnetic system 18 as a control member.

  In many cases, however, it is simpler to activate the magnetic system provided according to the invention only in the area where the member 14 approaches its closed position, in particular for reasons of construction. To this end, according to FIG. 3 which corresponds to the representation of FIG. 2 and on which the same reference numbers have been used, the invention proposes that a closing spring 20 in support located on the envelope side 10 acts on the member 14, which closing spring 20 however has the sole role of overcoming the friction between the member 14 and the fixed casing 10 and of moving the member towards a predefined approach zone, at the level of the sealing zone 12, o the magnetic system 18 provided according to the invention then takes care of ensuring the rest of the

  closing and guaranteeing the sealing force.

  As we can see now from the

  descriptions of Figures 2 and 3, arrangement of surfaces

  16o and 16u on the member 14 and on the casing side 10 can be freely chosen depending on the construction of the valve. Thus, these two surfaces can be formed for example directly by a valve head (16o) and a seat

valve (16u).

  As emerges from the closing force curve, the principle of which is shown in FIG. 2, the member 14 is increasingly accelerated by the magnetic force F in the direction of the sealing zone 12. To prevent the member 14 does not rebound when it reaches its closed position (x = 0), the invention proposes, according to FIG. 4, which corresponds to the representation of FIGS. 2 and 3, to provide a member forming a damping spring 22 which acts d 'on the one hand on the member 14 and is supported on the other side envelope. There is thus obtained, as shown in the qualitative curve of FIG. 2, in broken lines, a damping of the progressively accelerated displacement of the member 14 in the approach zone of the sealing zone.

  12, which prevents a rebound.

  As a damping spring member 22, it is possible, in a preferred embodiment, to directly use the elasticity of elastic sealing members provided at the sealing zone 12 and / or the sealing zone 17 provided on the organ side, for example O-rings, the elasticity of which is countered by the magnetic closing force F in the last zone

  approach to the sealing position.

  FIG. 4 has shown how, using a spring member, the closing force F produced by magnetic means can be optimally adapted, in particular in the area where member 14 approaches the sealing area 12, moving away from the characteristic magnetic force curve, that is to say how a damping of the force

  closing was carried out according to the stroke x.

  According to Figure 5, this can also be achieved in a much more flexible way thanks to the use

  of a permanent magnet / electromagnet device 18a.

  To this end, a travel detector 24 is provided, the

  output signal s (x) depends on the travel x of the member 14.

  The output signal s (x) of the detector 24 is amplified linearly or nonlinearly at a processing unit 26, and controls the electromagnetic current I of the electromagnets provided at the unit 18a. The detector 24 can consist extremely simply of an electric circuit section which closes when the member 14 approaches the sealing zone 12, and which puts the device

  electromagnets energized from that point on.

  It is quite possible to produce such a circuit section in the closure zone of the member 14, for example by using the member 14 itself as an electrical circuit section to activate the partial electromagnet device or the electromagnet device

unit level 18.

  Figure 6 shows a currently preferred embodiment of a valve of the invention, in the form of a vacuum valve. On the valve stem 14a which is part of the opening and closing member 14 of FIGS. 2 to 4 is mounted, axially movable, an armature 30 which

  is controlled by the field of a coil device 32.

  The armature 30 acts in the opening direction on a shoulder 14b of the valve stem 14a in order to lift the latter, and it is mounted on said valve stem 14a in order to be able to tilt. To this end, its bore 30b has a clearance with respect to the section of the valve stem 14a provided with a reduced diameter. In the open position of the valve, the armature 30 can thus be applied flatly, with its upper front surface, against the opposing surface

fixed 30c.

  The armature 30, which acts at the same time as a damping piston, slides in leaktight manner, thanks to seals 34, over a cylindrical bore 43 and defines therein, according to its position, cylindrical chambers

34o and 34u.

  A first input / output line 36u opens into the lower chamber 34u and a second line

  36o inlet / outlet opens into the upper room 34o.

  As current regulating members, filters are inserted in the input / output lines 36 having conductance values which can be chosen. These filters can be changed. As shown in broken lines at 38, there is provided in the armature 30, in addition to or in place of the lines 36, a discharge line in which a filter having a given conductance is preferably mounted

to be changed.

  The piston rod 14a acts on a valve head 40 on which a closing spring 42 is supported, which is itself in support on the envelope side. The valve head 40, which also forms part of the closing and opening member 14 of FIGS. 2 to 4, closes and opens a connection between the lines 44 and 46 of a vacuum system which is wrapped in the using a metal bellows 48 relative to the valve stem 14a provided with the closing spring 42, and

  to the damping / control unit.

  In the sealing zone surrounding the opening of the pipe 44 to be closed, an annular permanent magnet 50 is placed. This corresponds, according to the representations in FIGS. 2 to 4, to the case where the magnet device 18 is connected to the 'envelope 10. The valve head 40 is for example of soft iron, so that it is attracted by the annular magnet 50 provided on the valve seat. To prevent rebounding in the sense of the explanations for Figure 4, a seal 52 which should in any case be provided on the valve head, as shown, or on the valve seat or both, is designed so that during the final phase of closing the displacement of the valve head, the magnetic force of the magnet 50 must first work in compression against the elasticity of the sealing device 52, which prevents rebound. It is obviously quite possible to provide the magnet device at the level of the valve head, or even to provide magnet devices acting in the closing direction both on the envelope side and on the valve stem / valve head side. valve, to realize it from permanent magnets and / or electromagnets and / or to place the magnet device intended to generate the closing force at any place along the valve stem 14a o this can be done most simply from

by construction.

  Thus, with the embodiment of Figure 6, it would be quite possible to provide the magnet device at the armature 30, as shown in broken lines at 50a, but to put the armature 30 also in action in the closing direction, against

  a stop provided on the valve stem 14a.

  The closing spring 42 acts only with a weak force on the valve head 40, simply to bring it into the approach zone of the annular magnet 50, overcoming friction. The actual tight sealing lh is effected by the action of the magnet 50 on the head

valve 40.

Claims (9)

  1. Valve comprising a valve seat opening provided with a sealing part (12, 44), and a closing and opening member (14, 14a, 40) closing in the direction of said sealing part ( 12, 44) and moved in a controlled manner, characterized in that surfaces (160, 16u) facing each other and projecting along at least one component perpendicular to the direction of closing movement (K, A) of the member (14 , 14a, 40) are connected to the valve seat opening (44), on the one hand, and to the member (14, 14a, 40), on the other hand, which surfaces (16o, 16u) define an air gap, minimum in the closed position, which is crossed by a magnetic field (H) of a magnet device (18, 50, 40).   2. Valve according to claim 1, characterized in that it is provided, in the area of at least one of the surfaces (160, 16u), firmly connected to them, a   permanent magnet device (18, 50) and / or electro- magnets (18a).   3. Valve according to any one of   claims 1 or 2, characterized in that the field   magnetic (H) is controlled by a control signal (s (x)) which depends on the distance (x) between the sealing zone of the member (14, 14a, 40) and the sealing zone (12 ) located at valve seat level.   4. Valve according to any one of   Claims 1 to 3, characterized in that the member (14)   includes a drawer of a slide valve, and the part sealing (12) is linear.   5. Valve according to any one of   Claims 1 to 3, characterized in that the member (14a,   ) includes a valve stem (14a) and a valve head (40). 6. Valve according to any one of   claims 1 to 5, characterized in that the organ acts,   just before opening, against a body forming   spring (22, 52) acting in the opening direction.   7. Valve according to claim 6, characterized in that the spring member is formed by an elastic sealing member (52) provided on the closing and opening member (14, 14a, 40) and / or on the valve seat, in the sealing area (12). 8. Valve according to any one of   Claims 1 to 7, characterized in that a spring of   closure (20, 42) acts on the member (14, 14a, 40) in the closing direction, whereby the member is pushed as far as   in the area of action of the magnetic field.   9. Valve according to any one of   Claims 1 to 8, characterized in that it is designed like a vacuum valve.