Patent Publication Number: US-2022221081-A1

Title: A membrane for a moving a valve disk of a control valve, and a control valve

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention refers to a membrane for moving a valve disk of a control valve between a first position and a second position according to the preamble of claim  1 . The present invention also refers to a control valve according to the preamble of claim  8 . 
     BACKGROUND AND PRIOR ART 
     In larger milking installations, a problem to build up the milking vacuum quickly enough at startup of the milking installation may occur. The problem is related to the functioning of the membrane of the control valve that controls the shut off valve provided on the respective long milk conduit to the milking cluster. In order to build up the milking vacuum efficiently, after a shutdown of the milking installation, it is important that each shut off valve is properly closed to prevent ambient air from leaking into milking vacuum system. Thus the control valves have to be activated to control the respective shut off valve to be closed so that no air may leak into the milking vacuum system during building up of the vacuum. 
     Occasionally, the membrane of the control valve may not be able to lift the valve disk from a valve disk seat in one of its positions, in particular its first position in which vacuum, or low pressure, is allowed to pass through the outlet of the control valve. The valve disk may be attached to the valve disk seat in its first position in the control valve. In order to solve this problem, a solution with a coil spring mounted underneath the membrane has been tested. According to this solution, the valve disk is subjected to a force from the coil spring and biased away from the valve disk seat and the first position towards a second position. The idea is that the coil spring may assist the membrane in pulling the valve member away from the first position. However, the functionality of this solution is not perfect. Moreover, the solution is associated with increased service costs. 
     SUMMARY OF THE INVENTION 
     The purpose of the present invention is to overcome the problems discussed above. In particular, the purpose is to overcome the problem of the valve disk being attached in one of its positions. 
     The purpose is achieved by the membrane initially defined, which is characterized in that the membrane is designed with an inherent pre-tensioning of the flexible portion, which permits the flexible portion to exert a force on the valve disk from the first position towards the second position. 
     The inherent pre-tensioning of the membrane may assist a relatively high pressure or a relatively low pressure to move the valve disk away from the first position and towards the second position. The membrane may thus overcome the problem of the prior art that the valve disk get clogged or attached to the valve disk seat of the first position. Moving the valve disk from the second position to the first position may be less critical. Atmospheric pressure may, when applied, overcome the inherent pre-tensioning of the membrane to move he valve disk to the first position. 
     According to an embodiment of the invention, the flexible portion has a wavy shape, in particular in a cross-section, with a circular wave peak and a circular wave valley. Such a wavy shape may create the inherent pre-tensioning of the flexible portion to exert a pulling force on the central portion in a desired direction along the central axis, i.e. in particular from the first position. The cross-section may be parallel with the central axis. 
     According to an embodiment of the invention, the wave peak is located more closely to the central axis than the wave valley. The inner wave peak and the central portion may thus be lifted in relation the outer wave valley and the central portion. 
     According to an embodiment of the invention, the flexible portion comprises an intermediate annular flank extending between and connecting wave peak and the wave valley. The intermediate annular flank may slope from the wave peak to the wave valley. 
     According to an embodiment of the invention, the flexible portion has a thickness, wherein the thickness is thinner through the intermediate annular flank than through the wave peak and the wave valley. Such a thinner intermediate annular flank may improve the flexibility of the flexible portion. 
     According to an embodiment of the invention, the membrane has an active side and a passive side, wherein the outer annular rim portion has annular surface on the active side, wherein the wave peak is located above the annular surface in a rest position of the membrane. 
     According to an embodiment of the invention, the wave valley is located below the annular surface in the rest position. 
     The purpose is also achieved by the control valve initially defined, which is characterized in that the membrane is designed with an inherent pre-tensioning of the flexible portion, which permits the membrane to exert a force on the valve disk from the first position towards the second position. The inherent pre-tensioning of the membrane of the control valve may assist a relatively high pressure or a relatively low pressure to move the valve disk away from the first position and towards the second position, and thus prevent the valve disk from resting attached to the valve disk seat in the first position. 
     Various embodiments of the control valve are defined in the dependent claims  9  to  16 . For instance, the central portion of the membrane may be connected to the valve disk via a rod member extending through and attached to a central hole of the central portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is now to be explained more closely through a description of an embodiment and with reference to the drawings attached hereto. 
         FIG. 1  is a schematic illustration of a milking installation comprising a plurality of milking clusters. 
         FIG. 2  is a schematic cross-sectional view of a control valve of the milking installation in  FIG. 1 . 
         FIG. 3  is a schematic cross-sectional view of the control valve in  FIG. 2 . 
         FIG. 4  is a schematic perspective view of a membrane of the control valve in  FIGS. 2 and 3 . 
         FIG. 5  is a schematic view from above of the membrane in  FIG. 4   
         FIG. 6  is a schematic view from below of the membrane in  FIG. 4   
         FIG. 7  is a schematic cross-sectional view of the membrane along the line VII-VII in  FIG. 5 . 
         FIG. 8  is a schematic cross-sectional view of a part of the membrane in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION 
       FIG. 1  discloses a milking installation comprising a plurality of milking places, wherein each milking place comprises a milking cluster  1  having a number of teatcups  2  to be attached to the teats of an animal to be milked at the milking place. 
     Each milking cluster  1  may be connected to a vacuum pump device  3  via a respective long milk conduit  4 , a common vacuum conduit  5  and a milk receiver  6 . During milking, milk may thus be conveyed from the animals through the respective milking cluster  1 , the respective long milk conduit  4  and the common milk conduit  5  to the milk receiver  6  by means of the vacuum or low pressure provided by the vacuum pump device  3 . The milk collected in the milk receiver  6  may be conveyed to a milk tank  7  for delivery to a dairy. 
     A respective shut off valve  8  is provided on each long milk conduit  4 . The shut off valve  8  is configured to close or open the respective long milk conduit  4  for the low pressure to the respective milking cluster  1 . 
     The closing and opening of the shut off valve  8  is controlled by means of a control valve  9 , see also  FIGS. 2 and 3 . 
     The control valve  9  has an outlet  12 . The outlet  12  is connected to the shut off valve  8  as can be seen in  FIG. 1 . The control valve  9  is configured to connect the outlet  12 , and thus the shut off valve  8 , to a low pressure source, formed by the vacuum pump device  3 , or to a high pressure source, formed by the atmosphere, via a high pressure inlet  13 . 
     The control valve  9  comprises an outlet chamber  14 , which is connected to the outlet  12 . The outlet chamber  14  comprises high pressure port  15  and a low pressure port  16 . A valve disk  17  is provided in the outlet chamber  14  and is movable between a first position closing the high pressure port  15 , see  FIG. 2 , and a second position closing the low pressure port  16 , see  FIG. 3 . 
     The control valve  9  also comprises a pilot circuit  18 . The pilot circuit  18  is connectable to the low pressure source or the high pressure source. In the embodiment disclosed, the pilot circuit  18  is connectable to the low pressure source, i.e. the vacuum pump device  3 , via the common vacuum conduit  5 , the long milk conduit  4  and a low pressure inlet  19 . The pilot circuit  18  may alternatively be directly connected to the vacuum pump device  3  via the low pressure inlet  19 . 
     The pilot circuit  18  acts on a membrane  20 , which may have an active side  20   a  and a passive side  20   b , see also  FIGS. 4-7 . The passive side  20   b  is turned towards the valve disk  17 . The membrane  20  acts mechanically on the valve disk  17 . In the embodiment disclosed, the membrane  20  is connected to the valve disk  17  by a rod member  21  that may extend through the low pressure port  16 . 
     An actuator  22  is comprised by the control valve  9  and is configured to connect the pilot circuit  18  to one of the low pressure source  3  and the high pressure source. The actuator  22  may comprise a solenoid which acts on a magnetic disk  23  arranged in the pilot circuit  18 . 
     The pilot circuit  18  extends between the active side  20   a  of the membrane  20  and the passive side  20   b  of the membrane  20 . In  FIG. 3 , the pilot circuit is open from the active side  20   a  of the membrane to the passive side  20   b  of the membrane. In  FIG. 2 , the magnetic disk  23  shuts off the pilot circuit  18 . 
     The actuator  22  comprises a channel  24 , which may be provided to extend centrally through the solenoid of the actuator  22 , as is illustrated in  FIGS. 2 and 3 . In the embodiment disclosed, the channel  24  extends between the surrounding atmosphere and the pilot circuit  18 . The pilot circuit  18  is thus connectable to the high pressure source, i.e. the atmosphere, via the channel  24 . 
     The membrane  20  is configured to move the valve disk  17  to the first position when the pilot circuit  18  is connected to the high pressure source, i.e. to the atmosphere via the channel  24 , and to move the valve disk  17  to the second position when the pilot circuit  18  is connect to the low pressure source, i.e. to the vacuum pump device  3  via the low pressure inlet  19 . 
     In  FIG. 2 , the valve disk  17  is in the first position closing the high pressure port  15 . In the embodiment disclose, the actuator  22  is not activated, i.e. no electric current is fed to the solenoid thereof, so that the magnetic disk  23  may be moved away, for instance by the gravity force, from the solenoid to a primary position preventing the low pressure from passing through the pilot circuit  18  to the active side  20   a  of the membrane  20 . Atmospheric pressure may act on the active side  20   a  of the membrane  20  forcing the membrane  20  downwards which means that the membrane  20  forces the rod member  21  downwards so that the rod member  21  forces the valve disk  17  to the first position against the high pressure port  15 . 
     A low pressure may thus in the first position be guided through the control valve  9  via the low pressure inlet  19 , the low pressure port  16 , the outlet chamber  14  and out through the outlet  12  to the shut off valve  8 , which in response to the low pressure may open the long milk conduit  4  to permit low pressure, i.e. the milking vacuum, to act on the milking cluster  1  and the teatcups  2 . 
     In  FIG. 3 , the valve disk  17  is in the second position closing the low pressure port  16 . In the embodiment disclosed, the actuator  22  is activated, i.e. electric current is fed to the solenoid thereof, so that the magnetic disk  23  may be pulled to the solenoid to a secondary position closing the channel  24  and preventing the high pressure from passing through the pilot circuit  18  to the active side  20   a  of the membrane  20 . Instead the low pressure may act on the active side  20   a  of the membrane  20  pulling the membrane  20  upwards, which means that the membrane  20  pulls the rod member  21  upwards so that the rod member  21  pulls the valve disk  17  to the second position against the low pressure port  16 . 
     A high pressure may thus in the second position be guided through the control valve  9  via the high inlet  13 , the high pressure port  15 , the outlet chamber  14  and out through the outlet  12  to the shut off valve  8 , which in response to the high pressure may close the long milk conduit  4  to prevent the low pressure, i.e. the milking vacuum, from acting on the milking cluster  1  and the teatcups  2 . 
     The membrane  20  of the embodiment disclosed will now be further described with reference to  FIGS. 4-8 . It should be noted that  FIGS. 4-6  discloses a membrane member having two membranes  20 . The control valves  9  may be arranged side by side in a pair, wherein the membranes  20  advantageously may be manufactured with two membranes  20  as disclosed in  FIGS. 4-6 . However, for one control valve  9  only one, see  FIG. 7 , of the membranes  20  disclosed in  FIGS. 4-6  may be used. 
     The membrane  20  extends along an extension plane p. A central axis x of the membrane  20  is perpendicular to the extension plane p. The membrane  20  comprises an outer annular rim portion  31 , a central portion  32  and flexible portion  33 . 
     The outer annular rim portion  31  may have an annular surface  34  located on the active side  20   a  of the membrane  20 . The annular surface  34  may be parallel with the extension plane p. The central portion  32  may be circular and is configured to be connected the valve disk  17 . The flexible portion  33  is annular and provided between the central portion  32  and the outer annular rim portion  31 . The flexible portion  33  may adjoin and connect to the outer annular rim portion  31  and the central portion  32 . 
     The central portion  32  has a central hole  35 . The rod member  21  may extend through and be attached to the central hole  35  of the central portion  32 . 
     The membrane  20  is flexible to permit the central portion  32  to move back and forth along the central axis x, thereby permitting the valve disk  17  to move to one of the first position and the second position. 
     As initially mentioned, the membrane  20  may not always be able to lift the valve disk  17  from its first position in which the low pressure is allowed to pass through the outlet  12 . In order to overcome this problem, the membrane  20  is designed with an inherent pre-tensioning of the flexible portion  33 , which permits the membrane  20  to exert a force on the valve disk  17  from the first position towards the second position. The movement of the valve disk  17  from the first position shown in  FIG. 2  may thus be facilitated by the inherent pre-tensioning of the flexible portion  33 . It should be noted that the inherent pre-tensioning may not prevent the movement of the valve disk  17  from the second position when the high pressure acts on the active side  20   a  of the membrane  20  via the channel  24 . 
     As can be seen in particular in  FIGS. 7 and 8 , the flexible portion  33  may have a wavy shape, in a cross-section comprising the central axis x, with a circular wave peak  36  and a circular wave valley  37 . The wave peak  36  may be located more closely to the central axis x than the wave valley  37 . 
     The flexible portion  33  comprises an intermediate annular flank  38  extending between and connecting wave peak  36  and the wave valley  37 . The intermediate annular flank  38  may slope from the wave peak  36  to the wave valley  37 . As can be seen in  FIG. 8 , the intermediate annular flank  38  may slope outwardly and downwardly in relation to the extension plane p, and thus form an angle of inclination with extension plane p. 
     The flexible portion  33  has a thickness T. The thickness T may be thinner through the intermediate annular flank  38  than through the wave peak  36  and through the wave valley  37 . 
     The wave peak  36  may be located above the annular surface  34  in a rest position of the membrane  20 , and the wave valley  37  may be located below the annular surface  34  in the rest position. 
       FIG. 6  discloses the passive side  20   b  of the membrane  20 . The central portion  32  comprises a bottom surface  39  on the passive side  20   b . The bottom surface  39  may surround the central hole  35  and may be parallel with the extension plane p. The central portion  32  may comprise four grooves  40  extending through the bottom surface  39  and being arranged perpendicularly in relation to each other. The purpose of the grooves  40  is to permit the low pressure to pass through the low pressure port  16  in the first position of the valve disk  17 , see  FIG. 2 . 
     The membrane  20  may be manufactured of a plastic elastic material, for instance silicon rubber. The bending rigidity of the material of the membrane  20  may be at least 45 Shore, preferably at least 50 Shore. 
     The present invention is not limited to the embodiments disclosed but may be varied and modified within the scope of the following claims.