Abstract:
A multi-port rotary disc valve comprising a stator with a plurality of fluid flow ports and a rotary distributor with a plurality of channels arranged in a channel pattern. The channels are adapted to connect the ports between them and/or to the environment in a plurality of predetermined combinations, each combination being associated with an angular position of the rotary distributor with respect to the stator. The succession of combinations performed during a full or partial unidirectional turn of the rotary distributor constitute a predetermined sequence. The rotary distributor comprises a rotor and a mask mounted movably thereon, the rotor and the mask accommodating the plurality of channels. The mask is adapted to change the channel pattern by changing its position with respect to the rotor, thereby enabling the rotary disc valve to perform different predetermined sequences corresponding to different positions of the mask.

Description:
FIELD OF THE INVENTION 
     This invention relates to rotary disc valves for feeding fluid flow and/or pressure to a plurality of ports, in particular to valves performing a predetermined cycle of feeding operations, such as, for example, numerous cyclical inflating and deflating a plurality of pressure cells in an inflatable device. 
     BACKGROUND OF THE INVENTION 
     A rotary disc valve for inflating and deflating pressure cells in a therapeutic sleeve is disclosed in U.S. Pat. No. 5,014,681, incorporated herein by reference. This rotary disc valve comprises two discs: a stator disc with fluid flow ports connectable to a compressor and to the pressure cells, and a rotary distributor disc, the two discs contacting sealingly along a planar interfacing surface perpendicular to the axis of rotation. The ports of the stator disc open at the interfacing surface. The rotary distributor disc has a plurality of U-channels and through-going windows also opened at the interfacing surface. The channels and windows are configured so that during rotation of the rotary distributor disc, the compressor flow is successively directed, through the appropriate ports, to inflate the corresponding pressure cells, which are then successively opened to die atmosphere, all this following a predetermined sequence. 
     JP 01145474 discloses a rotary disc valve with a similar function where the stator comprises two discs fixed with respect to each other, the stator discs slidingly contacting a rotor distributor disc disposed therebetween. The rotor disc has U-channels and through holes connecting the ports of the stator in various combinations during one turn of the rotor distributor disc. 
     U.S. Pat. No. 4,614,205 discloses a multiport rotary disc valve with a similar function of simultaneous interconnection of a plurality of conduits in accordance with a predetermined cycle. The stator and the rotary distributor in this rotary valve are assemblies each comprised of two parallel plates or discs. The rotary assembly is sandwiched between two parallel plates of the stator assembly. Crossover pipes extend between the rotor plates to form either U-channels or through-passages similar to the above-cited designs. 
     The known rotary disc valves are capable of performing one predetermined cycle (sequence) of connections between the stator ports. The connections may be varied in time by controlling the rotational velocity and position of the rotor, but their order is determined by the pattern of the channels in the rotor and the stator. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a multi-port rotary disc valve comprising a stator with a plurality of fluid flow ports and a rotary distributor with a plurality of channels arranged in a channel pattern. The channels are adapted to connect the ports between them and/or to the environment in a plurality of predetermined combinations, each combination being associated with an angular position of the rotary distributor with respect to the stator. A succession of such combinations performed during a full or partial unidirectional turn of the rotary distributor constitute a predetermined sequence. The rotary distributor comprises a rotor and a mask mounted movably thereon, accommodating the plurality of channels. The mask is adapted to change the channel pattern by changing its position with respect to the rotor, thereby enabling the disc valve to perform different predetermined sequences corresponding to different positions of the mask. 
     In a preferred embodiment the mask and the rotor are coaxial and co-rotatable discs driven by a reversible controllable electric drive. The rotary distributor is mounted rotatably relative to the stator in a first direction only, while the mask disc is mounted rotatably relative to the rotor disc in a second direction only, contrary to said first direction. Thereby, the rotary distributor rotates only when electric drive rotates in the first direction and the mask disc rotates relative to the rotor disc only when the drive rotates in the second direction. 
     In a further embodiment of the rotary disc valve, the rotor disc has two faces, at least part of the rotary distributor channels connecting them. The first face sealingly contacts with a face of the stator, the connections between the stator ports and the rotary distributor channels being performed via this face. The second face sealingly contacts with a face of the mask disc, and the mask disc changes the channel pattern by switching connections between those channels that exit at the second face. 
     The rotary disc valve used for inflating and deflating N cells comprises a central inlet port and N outlet ports disposed around the central port. The rotor disc has a feed channel configured so that, during one turn of the rotary distributor, it successively connects the central inlet port to each one of the outlet ports. 
     The rotary disc valve is also adapted for group exhaust of all N inflated cells. For this purpose, the rotor disc has N through windows connecting the first face to the second face, configured so that, in a predetermined angular position A of the rotary distributor with respect to the stator, the N through windows match the N outlet ports. The mask disc has a group exhaust channel configured so that, in a predetermined angular position B of the mask disc with respect to the rotor disc, the group exhaust channel is connected to all the through windows of the rotor disc. The group exhaust channel is her connectable to a source of vacuum such as the entry of a compressor or pump, thereby enabling a group evacuation of any volumes connected to the N outlet ports of the stator, provided the positions A and B are attained simultaneously. 
     Preferably, the rotary disc valve is adapted to work as a part of a computerized system for inflating and deflating in cycles N cells connected to the N outlet ports. The stator of the rotary disc valve has N through pressure openings each disposed adjacent to one of the outlet ports, and a pressure channel connecting the pressure openings to a pressure outlet. The rotor disc has a bypass channel configured so as to be able to connect, when rotated, anyone of the outlet ports to the corresponding adjacent pressure opening while keeping the rest pressure openings stopped, thereby enabling the measurement of pressure P C  in a volume connected to anyone outlet port. Preferably, the bypass channel is disposed behind the feed channel with respect to the first direction of rotation, so that the bypass channel is connected to outlet port No. n when, the feed channel is between outlet port No. n+1 and outlet port No. n+2, where n is an ordinal number of an outlet port, n increasing in the first direction. The system comprises a sensor to measure the pressure P 0  in the central inlet port, and a sensor to measure the pressure P C  in the pressure outlet. The system is programmed to terminate the inflation of a given cell at a predetermined instant value of the pressure P 0  in order to obtain a target established pressure P E  in that cell, and the system is adapted to correct this instant value in a next cycle if the measured pressure P C  in a current cycle is different from the target pressure P E . 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is an exploded view of a rotary disc valve according to the present invention; 
     FIGS. 2A,  2 B, and  2 C are, respectively, lower, upper and cross-sectional views of the stator disc shown in FIG. 1; 
     FIGS. 3A,  3 B, and  3 C are, respectively, lower, upper and cross-sectional views of the rotor disc shown in FIG. 1; and 
     FIGS. 4A,  4 B, and  4 C are, respectively, lower, upper and cross-sectional views of the mask disc shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIG. 1, a multi-port rotary disc valve  10  according to the present invention is shown for use, for example, with an inflatable device having a plurality of pressure cells. One example of such inflatable device will be used in the explanations, without any limitation to the scope of the invention. The device is a therapeutic massage sleeve with N annular cells embracing a human&#39;s limb (not shown here) as described in the incorporated U.S. Pat. No. 5,014,681. The annular cells are close to each other or even slightly overlapping, and they need to be cyclically inflated or deflated in different sequences depending on the therapeutic procedure. 
     The rotary disc valve  10  comprises a housing  12 , a stator disc  14 , a rotor disc  16 , a mask disc  20 , a coupling disc  22 , and a drive motor  24 , all adapted for coaxial assembly along axis  2  of the valve. 
     The housing  12  is a massive plate with a circular recess  26  accommodating the stator  14 , with a plurality of N outlet windows  28  disposed in a fan-like manner around the axis  2  at a predetermined uniform angular distance Δα from each other. The outlet windows  28  are connected by individual channels (not seen) to outlet ports  30 . In operation, the outlet ports  30  are connected by pipes to the inflatable cells of an inflatable device, such as a massage sleeve (not shown). The housing  12  has also a central inlet port  32  connectable to a source of pressurized fluid such as the discharge of an air compressor (not shown), an exhaust port  34 , and a vacuum port  33  connectable to a source of vacuum such as the entry of an air compressor. The housing also has a channel  35  for measuring the air pressure of the inlet flow and a channel  36  for measuring the air pressure in inflated cells, as will be explained in more detail below. 
     With reference also to FIGS. 2A,  2 B and  2 C, the stator  14  is a disc with a wide axial opening  38  and with a plurality of various through windows, recesses and channels. In particular, the stator  14  has N through outlet windows  40  matching the outlet windows  28  of the housing, and N through pressure openings  46  each disposed adjacent to an outlet window  40 . At the lower side of the stator that faces the housing  12  (FIG.  2 A), there are the exit sides of the N outlet windows  40 , an arcuate vacuum channel  42  concentrically embracing the windows  40 , and an arcuate cell pressure channel  44  concentric with the vacuum channel  42  internally connected to the N pressure openings  46 . The end  47  of the cell pressure channel  44  matches the inlet of the measurement channel  36  when the stator is mounted in the housing. An exhaust recess  48  located to match the exhaust port  34  of the housing  12  is in fluid communication with an exhaust window  50  at the upper side of the stator (FIG.  2 B), though a slit  51 . Also at the upper side of the stator, which faces the rotor  16 , are the entrance sides of the outlet windows  40 , and a plurality of recesses  52  disposed in a fan-like manner between the outlet windows  40 . The recesses  52  are displaced farther from the disc axis than the windows  40  and are internally connected to the exhaust channel  42  on the lower side of the disc. The pressure openings  46  connect the cell pressure channel  44  at the lower surface of the stator to the stator upper surface facing the rotor  16 . A long arcuate recess  54  has a wide opening  56  adapted to match the vacuum, port  33  in the housing  12  and is in fluid communication with the exhaust channel  42  through a slit  55 . An extension  58  of the recess  54  is connected thereto by a narrow passage  60 . 
     The stator  16  is sealingly mounted to the housing  12 , in the recess  50  thereof, and operates as one integral body with the housing. 
     With reference to FIGS. 3A,  3 B and  3 C, the rotor disc  16  has a blind central recess  62  at the lower side which faces the stator  14  (FIG.  3 A). At the same side, the rotor has a radial feed channel  64  extending from the recess  62  to a radius suitable to cover the outlet windows  40  on the stator  14  when the valve is assembled. A plurality of N+3 windows  66  are disposed in fan-like manner at one side of the feed channel  64 . The windows  66  are at an angular distance Δα from each other and from the feed channel  64  so as to be able to match the windows  40  on the stator  16  when the valve is assembled. A group of three windows  68 A,  68 B, and  68 C similar to the windows  66  are located at the other side of the feed channel  64 . A group of N openings  70  are disposed between the windows  66  farther from the axis  2  of the valve than the outer edge of the windows  66 . A single bypass recess  72  is placed in one and a half angular steps Δα from the feed channel  64 . The recess  72  has such radial extent that it can cover and establish fluid communication between a window  40  and a corresponding pressure opening  46  on the stator, when the valve is assembled (shown also in FIG. 2B, in broken line). The rotor has also a wide window  74  completing the arc of windows  66  and  68  to a full ring. A wide exhaust port  76  is disposed on the rotor farther from the axis  2  than the openings  70 , and is configured to match the recess  54  on the stator. On the circumference of the rotor disc  16 , there is a plurality of inclined teeth  78  constituting part of a ratchet mechanism, adapted for engagement with the coupling disc  22  (FIG.  1 ). 
     With reference to FIGS. 4A,  45  and  4 C, the mask disc  20  has a wide arcuate window  80  with radial extent similar to that of the windows  66  on the rotor  16  and angular extent suitable to cover N windows  66 , when the mask disc  20  is mounted on the rotor  16 . The mask disc  20  further has a group of three adjacent exhaust windows  82 A,  82 B and  82 C, and one remote exhaust window  84 , each adapted to match the exhaust port  76  on the rotor  16 . At the lower side of the mask facing the rotor  16 , there is a group exhaust recess  86 , shaped similarly to, and disposed adjacent the group of windows  82 . The group exhaust recess  86  communicates with an arcuate exhaust channel  88  which has angular extent, radial position and width suitable to match the openings  70  and to connect them all via the exhaust recess  86 , to the exhaust port  76  on the rotor, when the mask disc  20  is mounted on the rotor  16 . On the circumference of the mask disc  20 , there are three pairs of teeth  90  for coupling the mask disc to the coupling disc  22  (FIG.  1 ). 
     With reference to FIG. 1, the coupling disc  22  is a thin disc with three straight teeth  92  matching the teeth  90  on the mask disc  20 , and a spring pawl  94 . The coupling disc is fixed to the shaft (not seen) of the electric motor  24 . 
     The electric motor  24  is reversible and controllable by angular velocity and angular coordinate. The control system (not shown) comprises inter alia a sensor  96  for the angular position of the rotor disc  16 , and a sensor  98  for the angular position of the mask disc  20 . 
     In assembled condition, the rotor  16  sits on the stator  14  and is rotatably connected to the housing  12  by means of a one-way bearing  18  allowing rotation of the rotor only in direction A. The mask disc  20  sits rotatably on the rotor  16 . The coupling disc  22  engages the mask disc  20  by means of the teeth  90  and  92  for rotation of the mask in any direction. At the same time, the spring pawl  94  of the coupling disc  22  engages the teeth  78  of the rotor disc  16  forming a ratchet mechanism allowing the mask  20  to rotate with respect to the rotor  16  only in direction B. The stator  14 , the rotor  16 , and the mask  20  are pressed to each other for air tightness by a spring means (not shown). Thus, when the motor  24  rotates in direction A, the mask disc  20  and the rotor  16  rotate together, as a single body, and constitute a rotary distributor interacting with the stator  14  to feed the air coming from the air compressor to the outlet ports  30 , in a predetermined sequence. This manner of rotation is called “operational mode”. When the motor rotates in direction B, the rotor  16  stands still with respect to the stator  14  while the mask disc  20  slips relative to the rotor  16  to change its angular position relative to the rotor, thus making a different rotary distributor capable of performing a different predetermined sequence. This manner of rotation is called “setup mode”. Thereby, the inventive rotary disc valve can perform the function of several conventional multi-port disc valves. 
     A number of predetermined sequences are illustrated below by way of examples only. 
     Sequence A: Sequential Inflation—simultaneous deflation. 
     The mask disc  20  is rotated in direction B relative to the rotor  16  to a position where the exhaust window  84  matches the exhaust port  76 , and at the same time the wide arcuate window  80  of the mask covers all N windows  66  of the rotor. The initial position of the rotor  16  with respect to the stator  14  is with the feed channel  64  over the exhaust window  50 . This is a stand-by or idle mode where the pressurized air from the compressor comes via the central inlet port  32  and the axial opening  38  to the recess  62  and the feed channel  64 , and leaves the rotary valve through the exhaust window  50  and the exhaust port  34 . 
     As the rotor  16  starts to rotate in direction A, the feed channel  64  moves over the nearest outlet window  40   1  which is connected to the first annular cell and it starts to inflate. After a predetermined time, or after reaching a predetermined pressure in the first cell, the rotor moves on and the feed channel  64  now matches the nearest recess  52   1  which is connected to the exhaust channel  42 , while the fluid communication with the first cell is stopped. This is also a stand-by mode. After a predetermined time, the rotor moves on and the feed channel matches the next outlet window  40   2  to inflate the next cell. Thus, all N cells are successively inflated until the feed channel reaches the last outlet window  40   N . After a predetermined time, the rotor makes about ½ turn so that all N outlet windows  40  match the windows  66  and communicate with the atmosphere via the window  80  on the mask. Thereby, the cells are deflated simultaneously and the sequence A is completed. 
     Sequence B: Sequential Inflation—sequential deflation. 
     The mask disc  20  is rotated in direction B relative to the rotor  16  to a position where the exhaust window  82 A matches the exhaust port  76 , and at the same time the wide arcuate window  80  of the mask covers the windows  68 A,  68 B and  68 C of the rotor. The initial position of the rotor  16  with respect to the stator  14  is with the feed channel  64  over the exhaust window  50 , as above. 
     As the rotor  16  starts to rotate in direction A, the feed channel  64  moves over the nearest outlet window  40   1  which is connected to the first annular cell, and it inflates. Then, the rotor moves on and the feed channel  64  matches the nearest recess  52   1  (stand-by mode). After a predetermined time, the rotor moves on and the feed channel  64  matches the next outlet window  40   2  to inflate the next cell. At the same tine, the window  68 A of the rotor matches the first outlet window  40   1  and the first cell releases its pressure to the atmosphere through the window  80 . Thus, all N cells are successively inflated and each one is deflated when the next cell is inflated. 
     If, alternatively, the exhaust window  82 B of the mask is fixed opposite the exhaust port  76  of the rotor, then the window  80  of the mask will cover only windows  68 B and  68 C of the rotor. Thus, the outlet window  40   1  will be opened to the atmosphere only when the window  68 B matches it, which will happen when the feed channel  64  reaches the outlet window  40   3 . In a similar manner, when the exhaust window  82 C of the mask is fixed opposite the exhaust port  76 , the outlet window  40   1  opens to the atmosphere only when the window  68 C matches it and this happens when the feed channel  64  reaches the outlet window  40   4 . Thereby, the three exhaust windows  82 A,  82 B and  82 C of the mask, with the cooperation of the three windows  68 A,  68 B and  68 C of the rotor, provide for three sequences B each characterized by different delay of the cell deflation. 
     Sequence C: Active suction. 
     The mask disc  20  is rotated in direction B relative to the rotor  16  to a position where the group exhaust recess  86  matches the exhaust port  76 . The rotor  16  is now rotated, together with the mask disc  20 , in direction A with respect to the stator  14  to a position where the feed channel  64  is over the exhaust window  50 , in stand-by mode as above. The exhaust port  76  now is positioned over the arcuate recess  54  and is in fluid communication with the vacuum port  33  which is connected to the compressor entry. The arcuate exhaust channel  88  covers all openings  70  of the rotor which, in their turn, match the inlet windows  40 . Thereby, the compressor suction provides for the rapid deflation of the massage sleeve cells. 
     The rotary disc valve of the present invention may be advantageously used in a computerized system for inflating and deflating in cycles a plurality of cells connected to the outlet ports, for example in the therapeutic sleeve shown in U.S. Pat. No. 5,014,681. The system is programmable to terminate the inflation of each cell when a predetermined instant pressure P 0  is reached (i.e. by moving the feed channel  64  to stand-by position or to the next cell). However, the instant pressure P 0  during the inflation is transient and even if the system terminates the inflation at P 0 =P E , the established pressure P C  in the cell at a short time may turn out different from the target pressure P E . Another factor that may affect the established pressure P C  in the cell is the inflation of the next adjacent cell, especially when the cells overlap. The computerized system that controls the inflation-deflation process needs to measure the actual established pressure P C  in the cell in order to compare it to the target pressure P E  and to try to minimize the difference ΔP=P E −P C  when the next turn to inflate the same cell comes, by shifting the predetermined pressure P 0  for this particular cell. 
     The rotary disc valve facilitates the above process of precise achievement of target established pressure P E  in the inflated cells. The instant pressure P 0  is measured at the central inlet port of the rotary valve, by means of a pressure sensor connected to the channel  35 . The measurement of the established cell pressure P C , after the next cell is inflated, is provided by means of the bypass recess  72  on the rotor, which is located one-and-half angular steps Δα behind the feed channel  64  with respect to rotation direction A. When the feed channel  64  has inflated two successive cells via the respective outlet windows  40  and is in stand-by position halfway to a third outlet window  40 , then the bypass recess  72  covers the first outlet window  40  and a corresponding opening  46  on the stator. Thereby, fluid communication is provided between the first inflated cell and the cell pressure channel  44  that is connected to a pressure sensor via the measurement channel  36 , and the established cell pressure P C  is measured. 
     Although a description of specific embodiments has been presented, it is contemplated that various changes could be made without deviating from the scope of the present invention. For example, the mask may be movable with respect to the rotor not only by way of rotation but in any other way providing commutation of the rotor distributor channels; the mask may comprise plural movable parts; the rotor and the mask may be driven by other means than electric motor; the rotary distributor may be driven by one motor and the mask may be driven by another motor; the discs may contact therebetween along a conical or other surface of rotation, etc. Also, the stator may comprise two discs with inlet or outlet windows at either side of the rotary distributor in a manner similar to U.S. Pat. No. 4,614,205 or to JP 01145474, which are incorporated herein by reference.