Abstract:
A rotary valve having inner and outer sleeves includes multiple ports configured to provide pressure and vacuum pulses when the sleeves are rotated with respect to each other. A source of pressure and vacuum is connected to the rotary valve, and the inner sleeve is rotated to generate pressure and vacuum pulses. The alternating pressure and vacuum pulses may be used to remove obstructions in conduits such as piping systems. The rotary valve may also provide static positions where no vacuum or pressure is available. The valve may be motor driven and the pressure/vacuum pulse frequency may be controlled based upon the relative speed of rotation of the sleeves.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/629,124 filed Nov. 18, 2004, which is incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates to a rotary fluid flow valve, and more particularly relates to a rotary valve which produces pressure and vacuum pulses over a range of frequencies which may be applied to various types of conduits. 
   BACKGROUND INFORMATION 
   Clogs are a common problem in any device in which flowable materials flow through conduits and narrow passages. Examples of conduits in which clogs occur include drains of plumbing fixtures such as sinks, toilets, bathtubs and showers. Additional examples of conduits in which clogs can occur are automobile radiators/cooling systems, heat exchangers and marine engine cooling systems (outboard, inboard and inboard/outboard), especially those that use seawater for cooling. 
   One method for cleaning clogs in drains involves the use of a cable drain tool, such as a snake. However, tools such as these may damage plumbing fixtures and may prove difficult to use in some situations such as sinks and bathtubs with drains having narrow passages and/or a series of bends. Another method for cleaning clogs involves the use of high pressure devices such as a jetter, however, such devices may rupture plumbing joints. 
   A further method for cleaning drains includes using chemicals including caustics and acids. This method has drawbacks in that many types of chemicals may be highly detrimental to plumbing systems and plumbing fixtures and may cause personal injury and/or destroy metal fittings. Additionally, caustic chemicals may damage PVC pipes and acids may damage porcelain. 
   Although chemicals, abrasives, disinfectants and other agents may be used to remove grease, scale, bacteria, hair and other forms of material which block flow through various types of conduits, a limitation of these chemicals is their need to reach the surface of the conduit affected by the contamination in a uniform and effective way and to stay in contact long enough to be effective. The effect of gravity alone tends to force the chemical or agent to the lower surface of the conduits, leaving upper surfaces untouched and untreated. Mechanical methods, e.g., jetters, are sometimes employed to introduce cleaning solutions into contaminated conduits, but these tend to utilize very active chemicals or agents and reduce the contact time with the contaminated surface. Furthermore, such methods cannot negotiate many types of turns and traps in typical conduit installations. 
   Devices which manually apply pressure and vacuum pulses have been developed. Examples of such devices are described in U.S. Pat. Nos. 5,664,284; 5,193,245; 5,105,504; and 4,933,017, which are incorporated herein by reference. These devices have proven successful in clearing clogs in a wide variety of applications. 
   U.S. application Ser. No. 10/991,688 filed Nov. 18, 2004, which is incorporated herein by reference, discloses a modification of the devices in the above-noted patents in which an operator can variably control the amount of pressure and/or vacuum through the use of a controller mounted near the distal end of the hose of the device. 
   The above-noted devices may require the operator to move a control handle or lever back and forth from the pressure position to the vacuum position. The operator may thus manipulate the lever/handle too quickly or too slowly for effective wave action to be produced in the conduit. Also, to maximize the pressure or vacuum produced, the control lever/handle needs to be held tightly against the stop at the end of travel in either the pressure or vacuum directions. It would be desirable to eliminate the reciprocating action of the control lever/handle of such devices. 
   SUMMARY OF THE INVENTION 
   The present invention provides an apparatus and method for generating pressure and vacuum pulses through the use of a rotary valve. A pressure and vacuum source is connected to the rotary valve, and an output hose from the valve delivers alternating pressure and vacuum pulses to a conduit such as a piping system. The rotary valve may be generally cylindrical, with an inner cylindrical sleeve that rotates with respect to an outer cylindrical sleeve to align pressure and vacuum ports in the sleeves at different rotational portions. The inner sleeve may be motor driven at constant or variable rates which effectively produce the desired pressure and vacuum pulses. The motor or manual drive of the rotary valve may be uni-directional or bi-directional, and the alternating pressure and vacuum valve opening times may be controlled to provide precise chemical treatment positioning. Continuous rotation of the inner cylindrical sleeve avoids the problems associated with conventional reciprocating valve designs. The creation of alternating pulses or waves in accordance with the present invention allows chemicals, abrasives, disinfectants or other agents to be uniformly distributed on all inner surfaces of the conduit due to the pulse wave action generated by the rotary valve. 
   An aspect of the present invention is to provide a system for providing alternating pressure and vacuum pulses to a conduit. The system comprises a source of pressure and vacuum, and a rotary valve communicating with the source of pressure and vacuum. The rotary valve comprises an outer sleeve having pressure and vacuum ports in flow communication with the source of pressure and vacuum, and an output port for delivering the alternating pressure and vacuum pulses to the conduit. The rotary valve also comprises an inner sleeve including pressure and vacuum ports rotatably mounted at least partially inside the outer sleeve. When the inner sleeve is located at a first rotational position with respect to the outer sleeve, a pressure port of the inner sleeve is aligned with a pressure port of the outer sleeve to deliver pressure to the outlet port of the outer sleeve. When the inner sleeve is located at a second rotational position with respect to the outer sleeve, a vacuum port of the inner sleeve is aligned with a vacuum port of the outer sleeve to deliver vacuum to the outlet port of the outer sleeve. 
   Another aspect of the present invention is to provide a rotary valve for providing alternating pressure and vacuum pulses. The rotary valve comprises an outer sleeve including a pressure port structured and arranged for connection to a source of pressure, a vacuum port structured and arranged for connection to a source of vacuum, and an outlet port. The rotary valve also comprises an inner sleeve rotatably mounted at least partially inside the outer sleeve including a pressure port aligned with the pressure port of the outer sleeve when the inner sleeve is located at a first rotational position with respect to the outer sleeve, a vacuum port aligned with the vacuum port of the outer sleeve when the inner sleeve is located at a second rotational position with respect to the outer sleeve, and at least one outlet port in flow communication with the outlet port of the outer sleeve. 
   A further aspect of the present invention is to provide a method of generating alternating pressure and vacuum pulses. The method comprises providing a rotary valve having an outer sleeve and an inner sleeve rotatably mounted at least partially inside the outer sleeve. Pressure is delivered to a pressure port of the outer sleeve; vacuum is delivered to a vacuum port of the outer sleeve; and the inner sleeve is rotated with respect to the outer sleeve to deliver pressure through the pressure port of the outer sleeve, through a pressure port of the inner sleeve, through an outlet port of the inner sleeve, and through an outlet port of the outer sleeve to generate the pressure pulse. The inner sleeve is further rotated with respect to the outer sleeve to deliver vacuum through the vacuum port of the outer sleeve, through a vacuum port of the inner sleeve, through the outlet port of the inner sleeve, and through the outlet port of the outer sleeve to generate the vacuum pulse. 
   These and other aspects of the present invention will be more apparent from the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of a rotary valve system for delivering pressure and vacuum pulses through a rotary valve to a conduit in accordance with an embodiment of the present invention. 
       FIG. 2  is an isometric view illustrating a rotary valve in accordance with an embodiment of the present invention. 
       FIGS. 3-5  are longitudinal sectional views of the rotary valve of  FIG. 2 . In  FIG. 3 , an inner cylindrical sleeve having pressure and vacuum ports is rotated to a first position inside an outer cylindrical sleeve in which pressurized fluid such as air is delivered through the rotary valve to an outlet port of the valve. In  FIG. 4 , the inner cylindrical sleeve is rotated to a second position in which a vacuum is delivered through the rotary valve to the outlet port of the valve. In  FIG. 5 , the inner cylindrical sleeve is rotated to a no-flow position between the pressure and vacuum positions. 
       FIG. 6  is a side view of the rotary valve of  FIGS. 2-5 , showing the vacuum port of the inner cylindrical sleeve closing with respect to the vacuum port of the outer cylindrical sleeve, corresponding to rotation of the inner sleeve from the vacuum position shown in  FIG. 4  toward the pressure position shown in  FIG. 3 . 
       FIG. 7  is an isometric view of the inner cylindrical sleeve of the rotary valve shown in  FIGS. 2-6 , illustrating the location of the pressure and vacuum ports at staggered locations along the length and circumference of the inner cylinder. 
       FIG. 8  is an isometric view of an inner cylindrical sleeve similar to the inner sleeve of  FIG. 7 , with the pressure, vaccum, pressure exhaust, vacuum intake and outlet ports arranged at different circumferential positions. 
   

   DETAILED DESCRIPTION 
   The present invention will be discussed with reference to preferred embodiments of conduit treatment devices including rotary valves for generating pressure and vacuum pulses. Specific details are set forth in order to provide a thorough understanding of the present invention. The preferred embodiments discussed herein should not be understood to limit the invention. 
     FIG. 1  schematically illustrates a rotary valve system for delivering pressure and vacuum pulses in accordance with an embodiment of the present invention. The system includes a rotary valve  10  which is connected to a source of pressure and vacuum  12 . The pressure and vacuum source  12  may comprise a standard motor and blower combination, for example, motorized blowers as found in conventional vacuum cleaners, wet/dry vacs, and the like. Although a combined source of pressure and vacuum is primarily described herein, the source of pressure and vacuum may also include separate pressure and vacuum generators in accordance with the invention. A valve motor  14  is connected to the rotary valve  10  and serves to drive an inner cylindrical sleeve of the valve, as more fully described below. Any suitable valve motor  14  may be used, such as standard variable or constant speed electric motors or the like. A reversing motor may be used to provide alternating forward/reverse motion if desired for a particular application. Furthermore, stepper type motors may be used to position the fluid being driven by the alternating pressure and vacuum pulses. Such motors have the ability to vary the amount of time the rotary valve provides either pressure or vacuum. For example, pressure may be applied for a predetermined time to deliver a certain amount of chemical to a contaminated or clogged pipe some distance from the delivery point, followed by the generation of alternating pressure and vacuum pulses to treat that specific area. 
   The rotary valve  10  is connected by a pressure and vacuum outlet hose  16  to a conduit  18 . The conduit  18  may comprise plumbing systems, drains, cooling systems, heat exchangers, pipes, fluid delivery lines, beverage delivery lines, powder delivery lines, medical equipment requiring disinfecting, dental chairs and the like. The conduit  18  may contain a partial or total clog, residue, corrosion, contaminants or any other material which may be subjected to alternating pressure and vacuum pulses in accordance with the present invention. 
     FIG. 2  illustrates a rotary valve  10  in accordance with an embodiment of the present invention. The rotary valve  10  includes an outer cylindrical sleeve  20 , and an inner cylindrical sleeve  30  rotating in a direction as shown by arrow R. The outer cylindrical sleeve  20  includes a pressure port  21 , a vacuum port  22 , a pressure exhaust port  23 , and a vacuum intake port  24 . The outer cylindrical sleeve  20  also includes an outlet port  25 . The valve motor  14  rotates the inner cylindrical sleeve  30 . A cotter pin  41  or other type of fastener or arrangement may optionally be used to hold the inner sleeve  30  in the desired axial position in relation to the outer sleeve  20 . A handle  42  may be connected to the inner sleeve  30  in order to manually rotate the inner sleeve  30  if desired. 
   The inner cylinder may be rotated at any desired rotational velocity, depending on various factors including conduit pipe diameter, length, type of fluid, amount of fluid in the conduit pipe, etc. For example, rotational velocities of from about 1 to about 60 rpm or higher may typically be used when air is delivered through the rotary valve  10  to treat a water or other liquid containing conduit. In this case, the alternating pressure and vacuum pulses may be generated at a frequency of from about 1 to about 60 per minute, and each pressure and vacuum pulse may have a duration of from about 1 to about 60 seconds. However, any other suitable frequencies may be used depending on the particular application. 
     FIGS. 3-5  are longitudinal sectional views of the rotary valve  10 . In  FIG. 3 , the inner cylindrical sleeve  30  is rotated to a position which results in the delivery of pressurized fluid from the outlet port  25  of the outer cylindrical sleeve  20 . In  FIG. 4 , the inner cylindrical sleeve is rotated to a position in which a vacuum is delivered to the outlet port  25 . In  FIG. 5 , the inner cylindrical sleeve is rotated between the pressure and vacuum positions of  FIGS. 3 and 4 , respectively. 
   As shown in  FIGS. 3-5 , the pressure and vacuum source  12  is connected by a pressure line  13  to the pressure port  21  of the outer sleeve  20 . A vacuum line  15  is connected between the vacuum port  22  of the outer sleeve  20  and the pressure and vacuum source  12 . A pressure exhaust line  17  is connected between the pressure and vacuum source  12  and the pressure exhaust port  23  of the outer sleeve  20 . A vacuum intake line  19  is connected between the vacuum intake port  24  of the outer sleeve  20  and the pressure and vacuum source  12 . 
   The outer cylindrical sleeve  20  includes a circumferential channel  26  extending around its inner diameter in flow communication with the outlet port  25 . Several O-ring seals  28  are provided between the inner diameter of the outer sleeve  20  and the outer diameter of the inner sleeve  30 . The O-rings seals  28  are under slight compression between the outside diameter of the inner sleeve  30  and the inside diameter of the outer sleeve  20 . They do not significantly restrict the rotation of inner sleeve  30  with respect to outer sleeve  20 . Although not shown in the figures, additional seals may be provided adjacent to the various ports in order to provide additional sealing, if desired. 
   The inner cylindrical sleeve  30  includes a pressure port  31 , a vacuum port  32 , a pressure exhaust port  33 , and a vacuum intake port  34 . In addition, the inner sleeve includes an outlet port  35  which is in flow communication with the circumferential channel  26  of the outer sleeve  20 . As most clearly shown in  FIGS. 6 and 7 , the pressure port  31 , vacuum port  32 , pressure exhaust port  33 , and vacuum intake port  34  of the inner sleeve  30  are coordinated with the pressure port  21 , vacuum port  22 , pressure exhaust port  23 , and vacuum intake port  24  of the outer sleeve  20  in such a manner that rotation of the inner sleeve  30  with respect to the outer sleeve  20  results in different alignments of the various ports. In the embodiments shown in the figures, the various ports in the outer sleeve  20  and inner sleeve  30  are circular, with diameters smaller than the diameters of their respective sleeves, e.g., their diameters may be from about 1 to about 95 percent or greater of the outer diameters of their respective sleeves. 
   Referring to  FIG. 3 , the pressure port  31  of the inner sleeve  30  is aligned with the pressure port  21  of the outer sleeve  20 . Also, the vacuum intake port  34  of the inner sleeve  30  is aligned with the vacuum intake port  24  of the outer sleeve  20 . In this position, pressure from the source  12  is provided through the pressure line  13 , through the aligned pressure ports  21  and  31 , and into an interior chamber  36  of the inner sleeve  30 . The interior chamber  36  is formed by chamber baffles  37   a  and  37   b . In  FIG. 3 , the pressurized interior chamber  36  communicates through the outlet port  35  of the inner sleeve  30  and through the outlet port  25  of the outer sleeve  20  to pressurize the outlet hose  16  and/or the conduit  18 . 
   As further shown in  FIG. 3 , the inner sleeve  30  includes an open vacuum intake end  39  which communicates with the ambient atmosphere. In the position shown in  FIG. 3 , the pressure and vacuum source  12  draws a vacuum through the vacuum intake line  19 , vacuum intake port  24 , vacuum intake port  34  and open vacuum intake end  39 . Thus, in  FIG. 3 , the vacuum side of the pressure and vacuum source  12  is connected with the surrounding atmosphere. The vacuum port  22  of the outer sleeve  20  and the vacuum line  15  are effectively sealed off by the circumferential wall of the inner sleeve  30 . In addition, the pressure exhaust port  23  of the outer sleeve  20  and the pressure exhaust line  17  are effectively sealed off by the circumferential wall of the inner sleeve  30 . 
   In  FIG. 4 , the inner sleeve  30  has been rotated 180 degrees from the first pressure delivery position shown in  FIG. 3  to a second vacuum delivery position. In the vacuum delivery position of  FIG. 4 , the vacuum port  32  of the inner sleeve  30  is aligned with the vacuum port  22  of the outer sleeve  20 . Furthermore, the pressure exhaust port  33  of the inner sleeve  30  is aligned with the pressure exhaust port  23  of the outer sleeve  20 . As shown in  FIG. 4 , the pressure port  21  of the outer sleeve  20  and the pressure line  13  are effectively sealed off by the circumferential wall of the inner sleeve  30 . Also, the vacuum intake port  24  of the outer sleeve  20  and the vacuum intake line  19  are effectively sealed off by the circumferential wall of the inner sleeve  30 . In the position shown in  FIG. 4 , the vacuum generated by the source  12  creates a vacuum through the vacuum line  15 , aligned vacuum ports  22  and  32 , interior chamber  36 , and aligned output port  35  and outlet port  25 . The rotary valve  10  acts to draw a vacuum through the outlet hose  16  and/or conduit  18 . Pressure generated by the source  12  in  FIG. 4  is directed through the pressure exhaust line  17 , aligned pressure exhaust ports  23  and  33 , and into an open pressure exhaust end  38  of the inner sleeve  30 . The open pressure exhaust end  38  is open to the ambient atmosphere, e.g., through a central opening in the valve motor  14 . 
     FIG. 5  illustrates a rotational position of the inner sleeve  30  between the pressure delivery position shown in  FIG. 3  and the vacuum delivery position shown in  FIG. 4 . As shown in  FIG. 5 , none of the pressure or vacuum ports are aligned, thus preventing flow into the inner chamber  36  and through the outlet port  25 . In this no-flow transitional position, neither the pressure line  13  nor the vacuum line  15  are connected with the interior chamber  36  of the inner sleeve  30 , with the net affect being cancellation of the pressure or vacuum delivered through the outlet hose  16  and/or conduit  18 . This results in substantially no flow through the pressure and vacuum source  12 . 
     FIG. 6  is a view looking into the ports  21 ,  22 ,  23  and  24  of the outer sleeve  20  after some rotation of the inner sleeve  30 , i.e., a 45 degree rotation from the vacuum position shown in  FIG. 4 . As the inner sleeve  30  rotates in the direction of the arrows, the vacuum port  32  and the pressure exhaust port  33  of the inner sleeve  30  are closing, while the pressure port  31  and the vacuum intake port  34  are not yet opening. 
     FIG. 7  is an isometric view of the inner sleeve  30  of  FIGS. 3-6 , illustrating the locations of the pressure port  31 , vacuum port  32 , pressure exhaust port  33 , vacuum intake port  34  and outlet port  35  at their positions along the length and circumference of the inner sleeve  30 . 
     FIG. 8  illustrates an inner cylindrical sleeve  30  similar to  FIG. 7 , except the pressure exhaust port  33 , the vacuum port  32 , and the outlet port  35  are located at different locations around the circumference of the sleeve  30  in relation to the pressure port  31  and the vacuum intake port  34 . In  FIG. 8 , the pressure exhaust port  33  and the vacuum port are circumferentially offset 90 degrees from the pressure port  31  and the vacuum intake port  34 , versus an offset of 180 degrees in  FIG. 7 . Also in  FIG. 8 , the outlet port  35  is circumferentially offset 180 degrees from the pressure port  31  and the vacuum intake port  34 , versus being aligned in  FIG. 7 . Many other such modifications of the locations, shapes, sizes and numbers of inner sleeve ports, as well as outer sleeve ports, are possible in accordance with the present invention. 
   The shapes and locations of the ports in the inner and outer sleeves can be altered to adjust the rate of change from pressure to vacuum and vice-versa. Also, the number and size of the ports, and the size of the cylindrical sleeves can be adjusted to obtain various performance characteristics. By varying the geometry of the pressure and vacuum ports on the inner and outer sleeves, varied pulse forms may be created and fluid flow and direction may be adjusted. For example, instead of circular ports as shown in the drawings, other port shapes such as elliptical, triangular, square, etc., may be used to change the form of the pulse in the conduit. The running clearance between the outer and inner sleeves  20  and  30  should be minimized or sealed in order to reduce or eliminate leakage. For example, the clearance may be from 0 to 1 mm, typically from 0.01 to 0.05 or 0.1 mm. The configuration of the cylindrical sleeves can be changed to enhance compactness and facilitate motor drive. It is also possible to use a multiple of motor/blowers in series or in parallel to enhance performance. 
   Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.