FR2536825A1 - Device of the magnetically-controlled valve type comprising a reducer. - Google Patents

Abstract

The present invention relates to a valve capable of being used especially in radioactive-fluid circuits of nuclear power stations. The valve comprises a body 10 into which emerge two conduits 11, 12 capable of communicating between them, as well as a cap 20 which houses a shut-off 30 and members for moving the shut-off. The latter comprise permanent magnets 40 and a reduction gearing 54, 71, 74 and 81. A threaded stem 90, cooperating with a bush 80 of the gearing system, carries at its end a valve shut-off 30.

Description

 The pr (> scJste invention concc; z e an apparatus or tap, capable of fulfilling the functions of isolation and sealing on fluid circuits, in particular radioactive fluids used in the context of nuclear power plants.

 More specifically, the present invention relates to a tap of the type comprising a body into which open two conduits capable of communicating with each other, as well as a cap made of non-magnetic material tightly fixed on the body to define a chamber which houses a shutter intended interrupt. the communication between said conduits, as well as shutter movement control members which comprise at least one permanent magnet capable of being moved in rotation by means of an external part adapted to generate a magnetic field of rotary appearance.

Such devices are described in particular in United States patents No. 2,289,574, No. 3,347,262 (GIBSON), No. 3,355,140 (ANDERSEN), No. 3,908,959 (FICHTNER), and No. 4,232 695 (THE GARRETT CORPORATION), as well as in French patents and patent applications No. 1,200,372 (COTTON DE BENNETOT), No. 2,373,729 (AUTOCLAVE-ENGINNERS) and No. 2,456,892 (AUTOCLAVE
ENGINNERS), to which reference will be made for the proper understanding of the present invention.

 - All these valves must meet an imperative condition, which is that of watertightness to the outside.

 It is understood in particular that this imperative must be respected, in the context of nuclear power plants, when handling radioactive fluids.

On the other hand, said fluids are brought to very high pressures, which can exceed 20 M Pa (200 bars), and at temperatures between-val for example, 20 to 3400cl
In practice, it has been observed that all of the previously proposed taps cannot give full satisfaction, in the sense that when the fluid pressures exceed a given threshold, the torques applied to the shutter control members, thanks to the magnetic coupling between the internal permanent magnets and the external part is insufficient to move the shutter and bring the valve to the open position.

 In particular, as described in patent application No. 2 456 892, and as shown in particular in FIGS. 1 and 3, it has proved essential, with the devices hitherto proposed, to provide a mechanical part connected to the control members of the shutter, and accessible outside the tap after having passed through the wall of the body.

By mechanical intervention on this part, the movement of the shutter can easily be controlled. This said part therefore makes it possible to compensate for faults in the drive system comprising at least one permanent magnet. The seal between the part and the body is achieved by O-rings. However, it is easy to understand that such an arrangement cannot in any way produce a perfectly reliable seal. In other words, such an arrangement, which it has proved essential to use up to now, when the fluids to handle reach very high pressures, eliminates all the advantages linked to the permanent magnet control which made it possible to obtain a perfect seal with respect to the text and present by cons (there are 3 disadvantages of conventional taps or valves, such as those described in US Pat. Nos. 969,803 and 3,269,698.

It has also been proposed to equip the shutters with bellows, in order to solve the sealing problems, as described in particular in the patents of the United States of America No. 2,642,890 (SKEWIS), No. 4,166,607 (WEBB ) and 4,232,695 (THE
GARRETT CORPORATION). However, such valves do not have satisfactory reliability and therefore cannot be used with fluids for which permanent sealing is a primary imperative.

 There is therefore a need on the market to have taps of the aforementioned type, which are at the same time simple, robust, reliable and economical, which can be used with fluids, such as. radioactive fluids, reaching very high pressures on the order of 20 M Pa, and temperatures on the order of 3500C, while presenting a perfect seal vis-à-vis the outside, and this requiring effort very limited maneuvering. Preferably, such taps should furthermore require reduced maintenance, and, as far as possible, present a certain safety, allowing the tap to be handled only by a few given individuals.

 The present invention comes on this point to provide a solution to the problem previously posed, and proposes a new tap of the aforementioned type in which the members for controlling the movement of the shutter comprise a screw / nut system, one of the elements of which is integral with the permanent magnet to transform the rotational movement of the permanent magnet into translation, and in which the control members also comprise a shaft linked in rotation with said permanent magnets and which carries an external toothing on which meshes a first toothing of a. plurality of satellites whose second toothing meshes with a nut-type socket, of the screw / nut system, coaxial with the shaft, which has an external toothing, and an internal thread engaged with a rod immobilized in rotation in the body, but free in translation, and which carries at one of its ends said obturator, and by the fact that a heat exchanger is fixed on the valve body and / or the cap.

 As will appear on reading the detailed description which follows, the present invention makes it possible to obtain perfectly tight taps while requiring reduced operating torques.

 Preferably, the wall of the cap enveloping the permanent magnets is made of non-magnetic steel doped with boron ', - and the cap consists of two generally cylindrical parts assembled by thread, the cap itself being assembled by thread on the body.

 According to an important characteristic of the present invention, there are provided elastic washers playing the role of supporting the vi's / nut system and allowing axial compensation for differential expansions.

 According to another characteristic of the present invention, the permanent magnets are cobalt and rare earth metal magnets, and preferably the permanent magnets are cobalt and sanarium magnets.

 According to an advantageous characteristic of the present invention, the seal between the cap and the body is ensured by welding of joined lips.

 According to a particular embodiment, said external part adapted to generate a magnetic field of rotary appearance consists of a set of permanent magnets, mounted on the cap and capable of rotation around the axis of the screw / nut system, and preferably said set of permanent magnets is removable.

 This set of permanent magnets can be fitted with a torque limiter.

 According to another characteristic of the present invention, said shutter is housed in a chamber of the cap which communicates by LD through a calibrated bore with the high pressure fluid inlet pipe, so that the shutter is applied to the seat by autoclave effect.

 Other characteristics and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawing, given by way of nonlimiting example, in which the single figure represents an axial section view of 'A device according to the present invention.

 It appears clearly from an examination of the said appended figure, that numerous geometrical shapes of the parts making up a tap in accordance with the present invention must imperatively be observed so as to allow correct cooperation of these said parts. For these reasons, we will consider, in the following, that said appended figure is integrated ld pi-ésntc 'descriEtiorl, nar the reference made to it here, so that this figure clearly defines the geometric shape, and the arrangement of parts of a tap according to an embodiment of the present invention.

 In the figure, O-O has been referenced the longitudinal axis of the valve through which the cutting plane passes, and which corresponds to the direction of movement of the shutter.

 As shown in the single appended figure, the valve according to the present invention comprises a body 10 into which two conduits 11, 12 open, capable of communicating with each other, and a cap 20, made of non-magnetic material, and fixed sealingly on the body 10, to define a chamber 21 which houses a shutter 30 intended to interrupt the communication between said conduits 11 and 12, as well as displacement members of the shutter.

 More precisely, as shown in the figure, the body 10 delimits a valve or valve seat 13, of generally circular shape, equipped if necessary with a seat ring for the body (not shown in the figure). The median plane of the seat 13 is substantially perpendicular to the above-mentioned axis O-O which corresponds to the direction of movement of the shutter 30.

 More precisely, one of the conduits 11, of generally circular cross-section, opens into a blind bore 14 coaxial with the abovementioned axis O-O, and which opens at the bottom of the seat 13.

The conduit 11, as shown in the figure is itself slightly inclined relative to the median plane (referenced A-A) in the figure, of the seat.

 Similarly, the second conduit 12, of circular cross section, itself inclined with respect to the above-mentioned plane AA, opens into a chamber 15 generally cylindrical with axis OO formed at the upper part of the seat 13, opposite to the aforementioned bore 14.

 More specifically, as shown, the two cylindrical conduits 11 and 12, with respective axes 16 and 17, are substantially parallel.

 At their end opening onto the outside of the body 10, the conduits 11 and 12 are provided with any suitable conventional means capable of allowing their connection to the fluid circuit of an installation.

 In the figure, such connection means have been schematically represented and referenced respectively in 18 and 19.

 As shown in the single appended figure, the cap 20 consists of two parts 22, 23 of generally cylindrical shape assembled by thread at 24. The intermediate piece 23, which is open at its two ends, is also assembled by thread on the body 10, as shown in 25. The part 22, opposite the body 10 relative to the intermediate part 23, is open at its end adjacent to the intermediate part 23, but closed at its opposite end by a wall of general shape discolde, 26.

 More specifically, the part 22 is screwed inside the intermediate part 23, until radial bearing surfaces provided respectively on these two parts come into abutment.

In this position, annular lips provided on the outer periphery, on the one hand of the part 22, on the other hand of the intermediate part 23, are brought into contact. The seal between the two parts 22 and 23 is then ensured by welding lips-seals schematically referenced 27.

 Similarly, and as always shown in the single appended figure, the intermediate piece 23 is screwed inside the body 10, at 25, until radial bearing surfaces provided respectively on the piece intermediate 23 and on the body 10 abut. In this position, annular lips provided on the outer periphery, on the one hand of the intermediate piece 23, on the other hand of the body 10, are brought into contact. The seal between the intermediate piece-23 and the body 10 is then ensured by a weld of lips-joints schematically referenced 28.

 According to a characteristic of the present invention, the part 22 of the cap 20 is made of non-magnetic steel doped with boron, which makes it possible to produce a thin enclosure resistant to the pressure of the fluid. This arrangement proves to be particularly advantageous, insofar as this part 22 envelops permanent magnets 40 of the movement control members of the shutter 30 and constitutes an air gap.

 More precisely, said permanent magnets 40, of generally elongated shape, which are housed in the part 22 of the cap 20, constitute a generally cylindrical element which surrounds a shaft 50.

This shaft 50 expands coaxially to 1pave OO of the tap, and is immobilized in rotation relative to the magnets 40, by means of a key 51, parallel to the axis OO, which is engaged in a corresponding recess formed in the shaft 50, and enters a rectilinear groove 41, provided in the permanent magnets 40, parallel to the axis OO. According to an important characteristic of the present invention, the permanent magnets 40 linked in rotation with the shaft 50, are magnets of cobalt and of a rare earth metal.

 Preferably, said permanent magnets 40 are cobalt and sanarium magnets.

 The ends of the shaft 50 are introduced respectively into a blind bore provided in the discoid wall 26 of the part 22 of the cap 20, and into a through bore provided in a satellite carrier 60, the role of which will be explained in more detail below. of this description This planet carrier 60, of generally cylindrical shape, is engaged in a corresponding chamber provided in the intermediate piece 23 of the cap 20, and abuts against a radial bearing surface provided on the inner periphery of this piece intermediate 23.

 More specifically, the shaft 50 is guided at each of its ends by guide rings 29 and 61, engaged respectively in said blind bore of the discord wall 26 and in the satellite carriers 60.

 These guide rings 29 and 61 can be made of any suitable resistant material.

According to an advantageous embodiment, these rings 29 and 61 can be made based on an alloy of cobalt, chromium and tungsten. These rings 29 and 61 can be made of material sold under the registered trademark "STELLITE".

 In addition to the rotational connection existing between the permanent magnets 40 and the shaft 50, the permanent magnets 40 are immobilized in translation relative to the shaft 50, thanks to a washer 52 engaged on the shaft 50, on the side of the body 10 , which comes to bear against the radial surface of the magnets 40, and which is immobilized in this position, thanks to an elastic toric ring 53, engaged in an annular groove provided on the outer periphery of the shaft 50, on the side of the body 10 relative to washer 52.

 The shaft 50 comprises, in the vicinity of its end, body side 10, an external toothing 54.

This meshes with a first toothed wheel 71 of two satellites 70 of axes parallel to the axis O-O, and arranged on either side of it.

 Said first toothed wheels 71 of the satellites 70 have a number of teeth greater than the toothing 54 provided on the shaft 50.

The ends of the satellites 70 are introduced respectively into a planet carrier 120 and into blind holes with axes parallel to the axis
OO, provided in the intermediate part 23 of the cap 20. Of course, as also appears in the appended figure, the shaft 50 also passes through the planet carrier 120 while the satellites 70 pass through the planet carrier 60.

 The above-mentioned planet carrier 120, of generally cylindrical shape, externally threaded, is screwed into a corresponding thread provided on the internal periphery of the part 22 of the cap 20, until it abuts against a radial bearing surface presented by this part 22. To this end, the planet carrier 120 is advantageously provided, on the body side 10, with blind holes 21 capable of receiving an appropriate tool to ensure correct tightening of the planet carrier 120 on part 22.

 In a manner comparable to the shaft 50, the satellites 70 are guided by rings 72, 73, of cylindrical shape, engaged respectively on the body of the satellites 70 and on the end of these adjacent to the body 10. More precisely, the guide rings 72 and 73 are introduced respectively into the planet carrier 60 and into the blind bores provided in the intermediate part 23.

 Again, the guide rings 72 and 73 will be made of any suitable material, such as the material sold under the registered trademark STELLITE.

 As shown in the figure, the satellites 70 are provided, on the body side 10, with a second toothed wheel 74 having a number of teeth less than the first toothed wheel 71. This second toothed wheel 74 of the satellites 70 meshes with an external toothing 81 provided on the external periphery of a bushing 80 supported in an intermediate part 23, coaxial with the axis OO. The toothing 81 has a number of teeth greater than the second toothed wheels 74 provided on the satellites 70.

 The body of the sleeve 80 adjacent to the toothing 81, of generally cylindrical shape, is engaged in a corresponding bore provided in the intermediate part 23 of the cap 20, with the insertion of a cylindrical guide ring 82. Again, this ring guide will be made of any suitable material, such as for example material sold under the trademark "STELLITE".

 The axial immobilization of the sleeve 80 is ensured, on the body side 10, by a radial bearing surface presented by the intermediate part 23 of the cap 22, on the side opposite the body 10, by a ball bearing 85, and elastic washers 86 engaged on a cylindrical extension of reduced diameter of said socket 80. More precisely, as shown in the figure, the ball bearing 85 abuts against a radial bearing surface presented by the body of the socket 80, in the adjacent position to the teeth 81, while the elastic washers 86 are engaged in a bore of the satellite carriers 60, and come to bear against the bottom of the latter. Said elastic washers 86 thus compensate for the differential thermal expansions of the assembly.

 Indeed, it emerges from the examination of the appended figure, that the planet carrier 60 is free to move axially in the intermediate part 23, while the shaft 50, the satellites, and the bush 80 have freedom of movement axial limited, relative to their respective support.

 The system consisting on the one hand of the gear wheel 54 / gear wheel 71, on the other hand of the gear wheel 74 / gear wheel 81, constitutes a reduction gear adapted to transform the rotational movement of the permanent magnets 40, in translation of a rod 90 immobilized in rotation in the intermediate part 23. To this end, the rod 90 of generally cylindrical shape, and which extends coaxially to the axis OO, is provided, on the side opposite the body 10, with an external thread 91 capable of cooperate by engagement with a threaded blind orifice 87, formed in the aforementioned socket 80, coaxially with the axis OO.

 As shown in the appended figure, the immobilization in rotation of the rod 90 relative to the intermediate part 23 is produced by keys 92, of generally elongated shape, which extend parallel to the axis OO, on the outer periphery of the rod 90, said keys 92 being engaged in rectilinear grooves corresponding body formed in the intermediate piece 23, parallel to the axis OO.

 The end of the rod 90, body side 10, is provided on its outer periphery with an annular rib 95. The latter is immobilized in the aforementioned shutter valve 30.

 More specifically, the latter is composed of two parts 31 and 32 assembled by thread so as to enclose the annular rib 95 provided on the end of the rod 90.

 The shutter valve 30 is thus secured to the end of the rod 90, and guided in translation in a cylindrical chamber 33 formed in the intermediate part 23.

 More precisely still, preferably, the outside diameter of the shutter valve 30, of generally cylindrical shape corresponds to the inside diameter of said chamber 33, so that this shutter valve 30 is applied tightly against the wall of the room 33. Furthermore , a calibrated bore 34 provided in the intermediate part 23, connects the chamber 33 provided behind the shutter valve 30, with the high pressure inlet conduit 12 of the fluid.

 Such a calibrated bore 34 allows the shutter valve 30 to be applied tightly against the seat 13, since it allows the chamber 33 to be filled with high pressure fluid. Such an arrangement ensures a perfect seal at the seat 13 thanks to the autoclave effect thus obtained.

According to the embodiment shown in the figure, the end of the shutter valve 30 adjacent to the seat 13 has a generally spherical shape
Of course the shutter valve 30 can take any appropriate form. If necessary, the shutter valve 30 may be provided with a valve seat ring (not shown in the figure)
The assembly also comprises a heat exchanger 100 disposed on the outside of the intermediate part 23, and in close contact with the latter. The purpose of such a heat exchanger 100 is to evacuate the calories induced by the fluid, and thus limit the temperature of the interior assembly = the chamber 21.

 Preferably, the heat exchangers 100 are provided with internal fins not shown in the figure.

 In addition, cooling can be achieved by a conventional heat pipe, mounted on a heat exchanger 100.

 The external part 110 adapted to generate a magnetic field of rotary appearance capable of driving the permanent magnets in rotation 40, consists of a set of permanent magnets 111 of generally elongated shape, supported in a cylindrical housing 112 secured to a handwheel 113 which rests on the upper surface of the cap 20.

 More specifically, the permanent magnets 11l are immobilized in the cylindrical housing 112 by virtue of a support ring 114 immobilized in position by a threaded ring il 5 engaged in a corresponding thread of the housing 112.

 Of course, the external part 110 may take any appropriate form, the main thing being that it is adapted to generate a magnetic field of rotary appearance around the axis OO, so that by magnetic coupling it rotates the permanent magnets 40 of the system. In this case, such an external part provided with permanent magnets 111 can be rotated either manually or by any motorization not shown. Again, the permanent magnets 111 will preferably be cobalt magnets and a rare earth metal, such as a sanarium.

 The external part 110 is preferably removable. Thus, on the one hand, such a set of permanent magnets 111 can be used on different taps. On the other hand, insofar as such an assembly 110 is removable, the valve has a safety since it is necessary to have such an assembly 110 of permanent magnets to proceed with the control thereof.

 Preferably, the external part 110 is provided with a torque limiter. The latter can be achieved simply by friction assembly of the permanent magnets 111 in the corresponding cylindrical housing 112.

 It is easily understood that the gear reducer (toothed wheels 54 71, 74 and 81>, makes it possible to transform the rotational movement of the permanent magnets 40 into a translational movement of the rod 90, which requires a corresponding translational movement of the shutter valve 30.

 More specifically, the distance of the rod 90 from the seat 13 of the shutter causes the withdrawal of the shutter valve 30. Conversely, the approximation of the rod 90 of the seat 13 of the shutter causes the approximation of the valve 30, and carries by therefore the valve in the closed position.

The advantages of the valve according to the present invention with respect to previously existing devices are numerous. As an example, we can cite
- system ensuring perfect sealing towards the outside, and exceptional reliability, since the body 10 and the cap 20 delimit a chamber which is perfectly sealed from the outside thanks to the magnetic coupling produced between the permanent magnets 40 -and permanent magnets 111,
- high gear ratio of the drive system allowing low maneuvering forces on the external part 110 whatever the level of fluid pressure applied to the shutter 30,
- consequently reduced operating torque,
security presented by the system: it is impossible to open or close the tap without said external part 110 capable of achieving magnetic coupling between the permanent magnets 40 and the permanent magnets 111,
- fully bidirectional shut-off valve, that is to say that the valve according to the present invention is capable of fulfilling both the shut-off and sealing functions on the circuits of fluids, and in particular of radioactive fluids nuclear power plants, regardless of the fitting of the valve; however, it should be noted that the autoclave effect is applied to the shutter valve 30 only in the case where the duct 12 is connected to the high pressure fluid inlet pipe,
robustness resulting from the absence of bellows at the level of the shutter 30, whereas such bellows were commonly used in the prior art, as described in particular in US Pat. No. 4,232,695,
- absence of seals, which leads to particularly reduced maintenance, as well as to the elimination of corrosion attack on the valve stem,
- excellent reliability due to the simple screw / nut drive mechanism.

 Tests carried out on a valve in accordance with the present invention have made it possible to demonstrate that such a valve allows opening under a differential pressure at the shutter equal to 22.2 M Pa at a fluid temperature of 50 C.

Tests in the general conditions of service were carried out with the scales of variations of the parameters of state of the fluid as follows
- pressure: 0 to 18 M Pa,
- differential pressure: 0 to 18 M Pa,
- temperature: 20 to 3400C.

 Such tests have made it possible to demonstrate that the tightness of the valve, in sectioning and in the maneuverability were fully satisfactory.

 Of course, the present invention is not limited to the embodiment which has just been described, from which it will be possible to envisage numerous alternative embodiments in accordance with the spirit of the invention.

Claims (11)

 1. A valve of the type comprising a body (10) into which open two conduits (11,12) capable of communicating with each other, and a cap (20) made of non-magnetic material tightly fixed on the body so as to define a chamber ( 21) which houses a shutter (30) intended to interrupt the communication between said conduits, as well as shutter movement control members which comprise at least one permanent magnet (40) able to be moved in rotation by means of a part exterior (110) adapted to generate a magnetic field of rotary appearance, and a screw / nut system one of the elements of which is integral with the permanent magnet to transform the rotational movement of the permanent magnet into translation, characterized by the fact that the control members comprise a shaft (50) linked in rotation with said permanent magnets (40) and which carries an external toothing (54) on which meshes a first toothing (71) of a plurality of satellites (70. ) whose s second toothing (74) meshes with a socket (80> of the nut type, of the screw / nut system, coaxial with the shaft (50), and which comprises an external toothing (and an internal thread (87) engaged with a rod (90) immobilized in rotation in the body, but free in translation, and which carries at one of its ends said obturator (30), and by the fact that a heat exchanger (100) is fixed on the body (10 ) from the tap and / or the cap (20).  2. Tap according to claim 1, charac terized in that the wall of the cap (20) enveloping the permanent magnets (40) is made of non-magnetic steel doped with boron.  3. Tap according to one of claims 1 and 2, characterized in that the cap (20) consists of two parts (22,23) of generally cylindrical shape assembled by thread (24), and in that the cap (20) is itself assembled by thread (25) on the body (10).  4. Tap according to one of claims 1 to 3, characterized in that there are provided elastic washers (86) playing the role of support of the screw / nut system and allowing axial compensation for differential expansions.  5. Tap according to one of claims 1 to 4, characterized in that the permanent magnets (40) are cobalt magnets and a rare earth metal.  6. Tap according to claim 5, characterized in that the permanent magnets (40) are cobalt and sanarium magnets.  7. Tap according to one of claims 1 to 6, characterized in that the seal between the cap (20) and the body (10) is provided by a weld (28) of lip-seals.  8. Tap according to one of claims i to 7, characterized in that said outer part (110) adapted to generate a magnetic field of rotary appearance consists of a set of permanent magnets (111), mounted on the cap (20) and capable of rotation-around the axis of the screw / nut system.  9. Tap according to one of claims 1 to 8, characterized in that said set of permanent magnets (111) is removable.  10. Valve according to one of claims 1 to 8, characterized in that said set of permanent magnets (111) is equipped with a torque limiter.  11. Tap according to one of claims 1 to 10, characterized in that said shutter (30) is housed in a chamber (33) of the cap (20) which communicates by means of a calibrated bore (34) with the high pressure fluid inlet pipe (12), so that the shutter (30) is applied to the seat (13) by autoclave effect.