Abstract:
A valve including a shutter placed in a chamber which is arranged in the valve body and whose end is provided with a seat against which a plug-forming part of the shutter is pressed in the closed position of the valve and is remote in the open position thereof. The inventive valve also includes a magnetic control device provided with the shutter magnetic drive device disposed outside the chamber and displacing the shutter in the closed or open position thereof. The valve is characterized in that the magnetic control device includes at least one ball which is made of a magnetic material, disposed in the chamber and is coupled with an external magnetic drive device, wherein the ball is associated with the shutter in such a way that the shutter is driven in the chamber when the ball is moved by a magnetic drive device.

Description:
FIELD OF THE INVENTION 
     The present invention concerns improvements to valves comprising a shutter moving in a chamber one end of which is provided with a seat which the shutter bears against in a closed position of the valve or is moved away from in an open position of the valve, and wherein the movement of the shutter is obtained by a magnetic control device disposed outside the chamber and magnetically coupled to the shutter. 
     Such valves are intended in particular to be used in food product filling machines, in particular for liquids. 
     DESCRIPTION OF THE PRIOR ART 
     The document EP 0436214 describes a magnetic valve equipped with a shutter and a control member outside the tubular body of the valve. The shutter and the control member have magnetized portions and the control member can be moved along the body so that the magnetic attraction exerted when the control member is moving causes movement of the shutter to open or to close the outlet orifice of the valve. In that valve, the external control member is moved by a pneumatic system that is integrated into the body of the valve. 
     However, such a device has the drawback of high friction forces between the shutter and the inside wall of the chamber because the shutter, which is attracted by the externally situated magnet, may stick more or less strongly to said inside wall. This results in the risk of premature wear of the wall and/or the shutter and/or of deposition of particles in the chamber and their passage into the liquid to be distributed; furthermore, this kind of valve is difficult to clean, in particular in the friction areas, in, which the cleaning liquid cannot circulate or can circulate only with difficulty. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a valve arrangement in which the areas of friction between the body of the valve and the shutter are reduced or even eliminated in order to overcome the mentioned drawbacks. 
     According to the invention, a valve comprising a shutter placed in a chamber provided in the valve body, one end of said chamber being provided with a seat which a plug-forming part of the shutter rests against in a closed position of the valve and is remote from in an open position thereof and a magnetic control device including shutter magnetic drive means disposed outside the chamber for moving it either to its closed position or to its open position is characterized in that the magnetic control device further comprises at least one ball which is made of a magnetic material, disposed in the chamber and coupled to the external magnetic drive means, said ball being associated with the shutter in such a way that said shutter is driven in the chamber when the ball is moved by the magnetic drive means. 
     According to other features of the invention:
         the ball turns freely relative to the shutter;   the shutter includes at least one housing in which at least one ball is placed;   the valve is adapted to enable centering of the shutter in the valve body;   the shutter is associated with at least two balls that cooperate therewith and the body of the valve to provide centering by the external magnetic drive means;   the centering means are disposed inside the chamber, on the lateral wall thereof, to cooperate with the shutter;   the centering means are disposed on the shutter to cooperate with the internal lateral wall of chamber;   the centering means are fins;   the shutter is associated with at least two balls offset longitudinally relative to the axis of the shutter;   at least one section of the shutter is associated with at least two balls that are offset angularly relative to each other;   two separate sections of the shutter are each associated with at least two balls disposed so that the circumferential offset between two successive balls of the same section is less than or equal to 180°;   the (n) balls of a section are offset angularly by an angle equal to 360°/n.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will become apparent on reading the following detailed description given with reference to the appended drawings, in which: 
         FIG. 1  is a diagrammatic view in axial section of one embodiment of a valve of the invention whose magnetic control device comprises a single ball; 
         FIG. 2  is a diagrammatic view in cross section taken along the line AA in  FIG. 1 ; 
         FIG. 3  is a diagrammatic view in axial section of a first embodiment of the valve of the invention whose magnetic control device comprises two balls that are not placed on the same section; 
         FIG. 4  is a diagrammatic view in axial section of a second embodiment of the valve of the invention whose magnetic control device comprises two balls that are placed on the same section; 
         FIG. 5  is a diagrammatic view in axial section of a third embodiment of the valve equipped with two magnetic control devices each comprising two balls placed on the same cross section; 
         FIG. 6  is a diagrammatic view in cross section of one of the  FIG. 5  control devices; 
         FIG. 7  is a diagrammatic view in axial section of what is shown in  FIG. 6 , and constitutes a more detailed view of the areas immediately above and below the section line BB in  FIG. 5 ; 
         FIG. 8  is a diagrammatic view in axial section of another embodiment with more than one ball; 
         FIG. 9  is a diagrammatic view of the  FIG. 9  valve in cross section taken along the line CC in a plane defined by a ball and the drive means. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  a valve  110  is shown that is intended to be installed in a container filling installation, for example. 
     The valve  110  has a tubular general structure. At its center it includes a chamber  12 , here of cylindrical section, which is delimited by a central tube having an axis A 1 . 
     In the following description, the terms lower, upper, top, bottom, etc. are used with reference to the drawings for easier comprehension. They must not be understood as being limiting on the scope of the invention, in particular with regard to the orientation of the valve. The vertical orientation of the axis A 1  of the valve is merely appropriate to one preferred embodiment of the invention. 
     In the present example, the upper portion of the valve includes an orifice  115  which is adapted to be connected to a supply tank (not shown) and which opens into the chamber  12 . The section of this orifice  115  is smaller than the cross section of the chamber  12 . The lower portion of the chamber  12  ends at a closure seat  116  adapted to receive a corresponding portion of the shutter  20 . The seat  116  has a frustoconical general shape and is extended in the downward direction by a cylindrical portion of smaller diameter than the chamber  12  forming the outlet orifice of the valve as such. 
     The shutter  20  has two main portions:
         a first portion forming a plug  121  made of non-magnetic material which has a frustoconical section and is adapted to cooperate with the seat  116  of the valve in the closed position of the valve. The seal is reinforced by a seal  124  around the plug  121 .   a second portion in the form of a stem  122  which is axially aligned with the plug and consists of a non-magnetic material such as stainless steel. The outside cross section of the stem  122  is everywhere less than the inside cross section of the chamber  12  so that the shutter  20  is able to move freely in the chamber  12  both ways along the axis A 1 .       

     According to the invention, the control device comprises drive means  130  based here on coils or magnets  132  placed outside the body of the valve, and thus of the chamber  12 , and a magnetic material ball  123  placed inside the chamber  12 . 
     The ball is made of soft iron, pure iron or an alloy of one or both of these materials, for example. 
     According to the invention, the ball  123  is associated with the shutter  20  in order to drive it in translation in the body of the valve when the ball itself is driven by the coils or magnets  132 . To this end, a transverse housing  124  is formed in the body of the shutter  20 , for example in the vicinity of the top of the stem, and the ball is disposed in the housing. The dimensions of the housing are such that the ball can turn freely inside it. 
     Moreover, the diameter of the ball  123  is significantly less than the inside cross section of the chamber  12 , so that the ball can roll freely in the chamber  12  whilst being held in the housing  124  of the shutter  20 , in which it also turns freely. 
     In a manner known per se, the drive means  130  including the coils or magnets  132  are placed outside the valve body, and can be moved in a direction parallel to the axis A 1  (double-headed arrow  133 ), either downwards (valve closing direction) or upwards (valve opening direction) in such a manner as simultaneously to drive the ball, which in turn moves the shutter  20 . The drive means  130  may be moved by any appropriate drive device (not shown) such as a piston-and-cylinder. 
       FIG. 2  is a diagrammatic view of the  FIG. 1  control device in cross section taken along the line AA in  FIG. 1 . It shows the whole of the tubular valve body delimiting the chamber  12  in which the shutter  20  moves. The drive means  130  are outside the body of the valve. In the present example, the drive means  130  carry two diametrically opposed magnets  132  on respective opposite sides of the outside wall of the tubular body so as to orient the magnetic flux lines so that they converge substantially toward the center of the ball  123  to achieve the best possible coupling. 
     At least one longitudinal groove  113  is machined into the inside wall  120  of the chamber to allow the fluid to pass on either side of the ball  123 . At least two grooves  113  are preferably provided, as in the present example, evenly distributed at the periphery of the chamber: here two diametrically opposed grooves are shown. They are machined across the whole of the axial section of the chamber  12 . The ball is trapped between two circular arc-shaped areas  114  that are separated from each other by the grooves  113 , the distance between the two areas being slightly greater than the diameter of the ball, and the magnets are preferably disposed facing these areas. Thus the ball “rolls” preferentially on one of these areas, which constitutes a rolling area, according to the orientation of the magnetic field produced by the coils or magnets. It should be noted that the other area is not in contact with the ball, but facilitates centering it when assembling the valve; what is more, it could very well become a bearing area if the magnets were fitted the other way around, for example following a maintenance operation. When the shutter is moved to the open position, the fluid can flow in the two grooves  113  provided for this purpose. 
     The valve is moved to the closed position or the open position by moving the magnetic control device in the appropriate direction. Operation is optimized if the valve is positioned as shown in the figures, i.e. with the liquid inlet at the top and the outlet at the bottom, with the drive means disposed at a level lower than the ball when the valve is closed: with this kind of configuration, the plug tends to be forced onto the seat not only by magnetic attraction but also by the static pressure exerted on the ball. 
     The mode of operation that has just been described is exactly the same for other embodiments of the present valve except that the control device, i.e. the drive means  130 , and the number of balls and their disposition in the shutter  20  are modified. 
     In the  FIG. 3  embodiment, the valve  110  has a tubular general structure, is made from a non-magnetic material and delimits the chamber  12 . The fluid flows in the gap between the shutter  20  and the chamber  12 . 
     In this embodiment, in a similar way to what is shown in  FIGS. 1 and 2 , the its upper portion of the valve includes an orifice  115  that is adapted to be connected to a supply tank (not shown) and opens into the chamber  12 . This orifice  115  has a section smaller than the cross section of the chamber  12 . The lower portion of the chamber  12  ends at a closure seat  116  adapted to receive a corresponding portion of the shutter  20 . The seat has a frustoconical general shape and is extended in the downward direction by a cylindrical portion of smaller diameter than the chamber  12  forming the outlet orifice of the valve as such. The seat  116  seals the valve when closed by the facing plug  121 . 
     As can be seen in  FIG. 3 , the diameter of the upper portion of the stem  122  of the shutter is less than that of the chamber  12  and tends to increase in a frustoconical manner from the upper portion to the lower portion in which the plug  121  is located. 
     In this embodiment, the first portion of the control device of the shutter  20  comprises two balls  123  offset axially and diametrically. Two centering members  324  in the form of non-magnetic material lugs or fins for stabilizing the shutter  20  are placed on the stem  122  of the shutter  20  or alternatively on the inside wall  120  of the chamber  12  and center the shutter  20  in the chamber  12  at the same time as allowing free movement of the shutter  20 ; in other words, a gap is left between the centering members  324  and the inside wall  120  of the chamber  12  or alternatively the stem of the shutter  20 . 
     In this embodiment, the stem is provided with as many housings  124  as the device includes balls. Each housing  124  has dimensions such that when the shutter  20  is fitted, i.e. centered by the centering members  324 , each housing receives a ball, which can turn freely in said housing and on the lateral inside wall  120  of the chamber  12 . 
     Here the drive means  130  are such that each of the balls is associated with at least one coil or one magnet  132  of its own. Moreover, the coil(s) or magnet(s)  132  are fastened together so that they move at the same time. 
     The embodiment that has just described is merely one nonlimiting example of the invention. Other constructive dispositions might be encountered in which the distribution of the balls on the shutter  20  or the distribution of the bearing members  324  on the body of the shutter  20  or in the chamber  12  are modified. 
     In operation, the valve is normally held closed by the magnetic control device, which tends to cause the plug to bear on the seat, as well as by the weight of the shutter  20  and by the static pressure that is exerted on the balls if the coils or magnets  132  are disposed at a level such that their force of attraction is below the diametrical plane of the balls and if the valve is disposed vertically as shown in  FIG. 3  (with the plug at the bottom). In use, the drive means  130  and therefore the coil(s) or magnet(s)  132  are moved and the magnetic attraction tends to move the balls that drive the shutter  20 . 
       FIG. 4  shows another embodiment in which the control device includes two diametrally opposed balls placed on the same cross section. This arrangement further improves the operation of the shutter  20 . 
     The control device further includes drive means  130  adapted to take account of the arrangement of the two balls  123  on the same section. To this end, the drive means  130  include a cylindrical magnetic body that carries two diametrally opposed magnets  132  disposed on respective opposite sides of the outside wall of the tubular body delimiting the chamber  12  to obtain the best coupling between the magnets and the two balls. 
     Centering is improved by providing bearing members  324  under the control device consisting of the balls and on the tubular body of the valve or on the body of the shutter  20  to achieve the best possible centering. In the example shown, these members are fins carried by the shutter  20 . 
       FIG. 5  shows another valve embodiment similar to those described above except that centering is achieved in a different way. In fact, the valve comprises two identical control devices, each of which includes two balls  123  placed on the same cross section of the shutter  20 . The two devices are centered on the axis A 1  of the valve but are offset longitudinally on that axis by a distance “h” and are offset circumferentially relative to each other, preferably at 90°, for better distribution of the lifting force and better centering of the shutter  20 . In other words, the two balls of a first device are carried by a first plane passing through the axis A 1  of the valve and the two balls of the second device are carried by a second plane passing through the axis A 1  of the valve and perpendicular to the first one; also, the two balls of the same device are disposed on the same section perpendicular to the axis A 1 ; the two balls of the other one are carried by a second section perpendicular to the axis A 1  but offset from the first one by a distance “h”. As shown, guiding is preferably completed in a manner known in the art by two perpendicular fins  524  interleaved with each other and offset longitudinally relative to the control devices, here placed downstream of the devices in the direction of flow of the fluid, and carried by the stem of the shutter  20 . The stem  122  of the shutter  20  terminates in a frustoconical portion under which the plug  121  is situated. 
     This embodiment of the valve includes drive means  130  with two sets of coils or magnets  132  that are mechanically linked to each other to move at the same time and are disposed so that one provides the coupling with the two balls of one section and the other with the two balls of the other section, offset by a distance “h”. 
       FIG. 6  is a diagrammatic view of one of the control devices in cross section taken along the line BB in  FIG. 5 . It shows the whole of the tubular body of the valve delimiting the chamber  12  in which the shutter  20  slides by means of balls each of which is disposed in a respective housing of the shutter  20 . Outside the body of the valve are the drive means  130  that include a cylindrical magnetic body that carries two magnets  132  whose magnetic poles are preferably reversed relative to each other. They are placed on respective opposites sides of the outside wall of the tubular body to cause the magnetic flux to converge towards the two balls  123  in order to obtain the best coupling. 
       FIG. 7  is a view of the arrangement of the balls  123  and the shutter  20  in the chamber  12  of the valve in axial section taken along the line B-B in  FIG. 6 . In the same cross section of the shutter  20  there is a hole  733  whose diameter is such that the two balls  123  of the same section cannot stick together because of magnetic attraction. This arrangement is introduced into the chamber  12  of the valve so that it slides freely in translation. The other portion of the control device, i.e. the drive means  130  with the coils or magnets  132  is on the same cross section but outside the valve body. 
     The operation of this type of valve is identical to that described with reference to the previous figures. 
     In the embodiment described with reference to  FIGS. 8 and 9 , the latter figure being a view in section taken along the line CC in  FIG. 8 , the valve includes drive means  130  with two sets of coils or magnets  132  placed outside the body of the valve and offset longitudinally on the axis A 1  so that each magnetizes two balls  123  disposed on the same cross section of the shutter. The two sets of coils or magnets  132  are also fastened together so that they move at the same time. Each set is similar to the  FIG. 5  set, i.e. it includes a body with two coils or magnets  132  on respective opposite sides of the outside wall of the tubular body so as to orient the magnetic flux lines to obtain the best coupling with the balls. 
     The shutter  20  terminates in a plug  121  in its lower portion extending the stem. A seal  829  preferably surrounds the plug, as shown here. 
     The plug has a frustoconical section intended to cooperate with a seat  116  of the valve to provide a seal in the closed position. 
     The shutter  20  is preferably machined from a single blank so that fitting it does not necessitate any welding which could introduce the risk of causing deformation at the level of the joint when it is being welded. That kind of operation would therefore have the effect of diminishing the accuracy of the centering of the shutter  20  in the chamber. 
     As can be seen in  FIG. 8 , the plug is surmounted by another frustoconical section  821  that is surmounted by two perpendicular fins  825  interleaved one within the other that center the shutter  20  in the chamber  12  of the valve at the same time as allowing the liquid to circulate between the fins  825  at  950  ( FIG. 9 ). 
     The fins are surmounted by a cylindrical portion  826  whose diameter is less than the diameter of the chamber  12  and which is itself surmounted by two other portions  827 ,  828  that are offset longitudinally by a distance “h” and each of which contains the two balls  123  mentioned above placed on the same cross section. These two portions  827 ,  828  are separated from each other by a cylindrical intermediate section  830 . As before, the balls in the same section are preferably diametrally opposed; the balls are offset circumferentially by 90° from one section to the other. 
     The inside diameter of the chamber is preferably substantially equal to the sum of the diameters of the two balls. 
     The balls of the same section are disposed in a housing  824  consisting here of a transverse bore formed in the stem which has a diameter significantly greater than that of the balls so that the latter may move freely therein. It should be noted that the fins  825  are machined from the same blank as the stem. 
       FIG. 9  is a view in section taken along the line CC in  FIG. 8  showing the shutter with the housing  824  in which the two balls  123  of the section are housed, the relative disposition of the balls and the fins  825  and the passages  850  that are left free for the fluid. 
     Of course, the invention is not limited to the embodiments described and design variants may be applied thereto without departing from the scope of the invention as defined by the claims. In particular, the control device may be equipped with a different number of balls (more than two balls per section; more than two sections equipped with balls). 
     Although the only embodiments shown in the figures are on/off valves, the production of variable flow valves may be envisaged, for which purpose it suffices to vary the dimensions of the gap between the chamber  12  and the shutter  20 .