Abstract:
A peristaltic pump includes a support section and a rotor mounted for rotation on the support section. There are a pair of spaced apart cam elements attached to and extending from the rotor. A drive mechanism rotatably operates the rotor such that the cam elements are turned together with the rotor. There are first and second mounting sheaves connected to the support section. Each mounting sheave has a groove formed peripherally therein. An elongate, resilient tube conducts liquid therethrough. The tube includes leading and trailing tube segments and an intermediate tube segment formed longitudinally therebetween. The leading segment is retainably inserted in the groove of the first sheave and the trailing segment is retainably inserted in the groove of the second sheave to hold the intermediate segment of the tube for being operatively engaged by the cam elements as the rotor is operated. This causes liquid to be pumped peristaltically through the intermediate segment of the tube from the trailing segment to the leading segment.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved peristaltic pump and, in particular, to a peristaltic pump utilizing a resiliently flexible fluid conducting tube that is releasably attached to a pair of “quick connect” mounting sheaves. 
     BACKGROUND OF THE INVENTION 
     Low volume peristaltic pumps are currently utilized in a wide variety of industrial applications (e.g. water treatment, mining, chemical processing) where abrasive, corrosive and/or viscous liquids must be pumped. Such pumps employ the principal of peristalsis to deliver the fluid through a flexible tube or hose. Peristaltic pumps have no valves or seals and the pump fluid contacts only the interior of the tube. As a result, the pump is fairly easy to clean and sterilize. Even caustic and/or abrasive fluids exert little wear and tear on the pump parts so that maintenance is simplified considerably. By the same token, the gentle pumping action exhibited by the peristaltic pump causes little, if any, damage to the tube, particularly when compared to the wear and deterioration typically experienced by components of other types of pumps. Because the pump fluid is contained completely within the tubing, there is little, if any, opportunity for the fluid to be contaminated. 
     To date, most maintenance required for peristaltic pumps has involved inspecting, cleaning and/or changing the fluid conducting tube. Virtually all low volume peristaltic pumps have utilized a relaxed tube. Such tubing tends to deteriorate after prolonged use and requires periodic replacement. The tube may also require occasional cleaning. In such situations, the tubing must be fully disconnected from the peristaltic pump. Conventionally, opposing ends of the tubing are attached by clamps or brackets to the frame or body of the pump. Such means of attachment must be painstakingly manipulated opened and/or disconnected before the tubing can be removed. After the tube is inspected, it is cleaned and replaced as needed. In either case, the tubing must be tediously reattached to the pump by the aforesaid clamps or brackets. This tends to be a time consuming, annoying and inconvenient procedure that prolongs the pump&#39;s downtime. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide for an improved durable and easy to service peristaltic pump, which utilizes a long-lasting pump tube that requires infrequent maintenance and replacement. 
     It is a further object of this invention to provide a peristaltic pump that allows the pump tubing to be removed and replaced much more quickly and conveniently than is accomplished in conventional peristaltic pumps so that pump maintenance is facilitated considerably. 
     It is a further object of this invention to provide a peristaltic pump wherein the pump housing is mounted to the pump without requiring brackets, clamps or other components that are awkward, tedious and time consuming to operate. 
     It is a further object of this invention to provide a peristaltic pump utilizing a quick connect form of flexible tubing that greatly facilitates pump maintenance. 
     This invention results from a realization that the maintenance and repair of a low volume peristaltic pump may be facilitated considerably by utilizing a resiliently flexible pump hose or tube that is connected at respective ends to a pair of “quick connect” mounting sheaves. This mounting structure allows the hose to be quickly and conveniently removed from and replaced on the pump as required and without the need for clamps, brackets or the like, which are typically time consuming, tedious and annoying to use. 
     This invention features a peristaltic pump including a support section and a rotor mounted for rotation on the support section. There are a pair of spaced apart cam elements attached to and extending from the rotor. A drive mechanism rotatably operates the rotor such that the cam elements are turned together with the rotor. There are first and second mounting sheaves connected to the support section. Each mounting sheave has a groove formed peripherally therein. An elongate, resilient tube conducts liquid therethrough. The tube includes leading and trailing tube segments and an intermediate tube segment formed longitudinally therebetween. The leading tube segment is retainably insertable in the groove of the first mounting sheave and the trailing tube segment is retainably insertable in the groove of the second mounting sheave to hold the intermediate segment of the tube for being operatively engaged by the cam elements as the rotor is operated. As a result, liquid is pumped peristaltically through the intermediate segment of the tube from the trailing segment to the leading segment. 
     In a preferred embodiment, the drive mechanism may include a rotary motor and a reduction device that operatively interconnects the motor and the rotor. The reduction device may include a belt that operatively connects an output of the motor to the rotor. The output may include a toothed pulley and the rotor may include a circumferential series of teeth. The drive belt may include a complementary set of teeth that operatively interengage the tooth pulley and the circumferential teeth on the rotor. 
     The cam elements may include rollers mounted for axial rotation on the rotor. The cam elements may be positioned generally 180° apart on the rotor. The rollers may extend generally parallel to one another. 
     A pair of tube retainer elements may be attached to the support section. Each retainer element may be positioned adjacent to a respective mounting sheave for holding the leading and trailing segments of the tube in respective grooves of the sheaves. 
     The tube may include an elongate stretch tube. The tube may be composed of Norprene™. 
    
    
     
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       Other objects, features and advantages will occur from the following description of a preferred embodiment and the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a low volume peristaltic pump according to this invention; 
         FIG. 2  is a side elevational view of the peristaltic pump; 
         FIGS. 3 and 4  are front elevational views of the pump depicting sequential rotation of the rotor and corresponding operation of the pump such that fluid is moved through the resilient tubing; 
         FIG. 5  is a rear elevational view of the peristaltic pump; and 
         FIG. 6  is a perspective view of the pump with the tube shown in fragmentary fashion and disengaged from the mounting sheaves. 
     
    
    
     There is shown in  FIGS. 1-6  a low volume peristaltic pump  10  that is designed for pumping liquids in various applications. Pump  10  may be used for a wide variety of industrial uses, such as in the chemical water treatment, mining and other industries. The particular technology, application and/or environment in which pump  10  may be utilized is not a limitation of this invention. 
     Pump  10  employs a base  11 , which carries a plurality of rubber of plastic feet  13  for engaging a underlying table or other generally horizontal supportive surface. Feet  13  help to minimize movement of the pump across the supportive surface during operation of the pump. Base  11  is unitarily attached to a cylindrical motor accommodating casing  14 , which circumferentially surrounds and receives a rotary motor  16  ( FIG. 5 ). Motor  16  preferably comprises a 12 volt or 24 volt DC motor. The motor may also be adapted in a standard manner for alternating current operation. The size of the motor may be varied to achieve corresponding pumping capacities in a manner that will be understood by persons skilled in the art. Base  11  and casing  14  may be composed of various lightweight yet durable plastics, metals or metal alloys. 
     A support section  12  abuts an inner end of cylindrical casing  14 . Support section  12  comprises a plate-like bracket having a generally vertical wall  20  and a pair of opposing flanges  22  formed along respective vertical edges thereof. A pair of screws  21  ( FIGS. 3 and 4 ) interengage wall  20  and adjoining motor  16  ( FIG. 5 ). This holds support section  12  upright. The flanges  22  widen proximate the lower ends thereof and form parallel side walls  24 . Preferably, support section  20  comprises a one-piece construction and is composed of aluminum or some other durable plastic, metal or metal alloy material. As used herein, the “support section” should be construed broadly to include any and all structure used to support the rotor for axial rotation. In alternative embodiments, support section  12  may be attached directly to base  11  and/or motor casing  14 . 
     A plastic rotor  26  is axially rotatably mounted to wall  20  of support section  12 . In particular, rotor  26  is mounted on a pivot  28 , which may comprise a bolt, bushing, rivet or other comparable structure for axially rotatably mounting rotor  26  to support section  12 . For example as depicted in  FIGS. 1-5 , pivot  28  may comprise a bolt  30  that extends through aligned holes in rotor  26  and wall  20 . Bolt  30  is secured to wall  20  by a nut  32 ,  FIG. 5 , and a washer  34 . The rotor thereby rotates axially freely about bolt  30 . 
     Rotor  26  includes a series of axial teeth  27  that are formed circumferentially about the rotor. This facilitates operation (turning) of the rotor in the manner described more fully below. Rotor  26  also carries a webbing  36  on the side of the rotor facing away from wall  20 . Webbing  36  includes four receptacles  38  that are spaced 90° apart from one another on rotor  26 . Each receptacle  38  includes a threaded interior circumference. This enables a pair of selected receptacles  38  to be engaged by respective cam rollers  40 .  FIGS. 1-4  and  6  particularly depict a pair of cam roller components that are axially rotatably attached to and extend from rotor  26 . Each roller  40  includes an interior hex screw that is threadably interengaged with a respective receptacle  38 . The two cam rollers  40  are attached to a pair of receptacles  38  that are spaced 180° apart on rotor  26  such that the cam rollers  40  are likewise positioned 180° apart. Each cam roller element includes an outer cylindrical roller  42 , which is axially rotatably mounted on a respective hex bolt  39  of the cam roller component. As a result, exterior rollers  42  rotate about the respective hex bolts which are in turn secured to respective receptacles  38  of rotor  26 . 
     A drive mechanism  50  is employed for operatively turning rotor  26 . The drive mechanism comprises the previously described DC motor  16 , which is mounted in cylindrical casing  14 , and a reduction mechanism  51  for operatively interconnecting the motor to the rotor. More particularly, the motor includes an output shaft  52  that extends through a lower hole (not shown) in wall  20  of support section  22 . Rotary output shaft  52  carries a toothed pulley  54 , which is analogous to rotary, motor driven pulleys utilized in conventional peristaltic pumps. 
     Pulley  54  and rotor  26  are operably interconnected by a drive belt  60 . The drive belt is preferably composed of a flexible rubberized or elastomeric material and includes a series of teeth on the inner surface  62  thereof. These teeth cooperate with the teeth of pulley  54  and the peripheral teeth  27  of rotor  26 . As a result, when pulley  54  is driven rotatably in a clockwise direction, for example, rotor  26  is similarly driven by the reduction mechanism comprising pulley  54  and belt  60  in the clockwise direction as indicated by arrows  66  in  FIGS. 1 ,  3 ,  4  and  6 . 
     A pair of first and second mounting sheaves  70  and  72  are attached to respective side walls  24  of support section  12 . Each sheave is preferably composed of a high-strength, durable plastic and features a generally circular, disk-like shape with a groove  76  formed circumferentially therein. Each groove  76  surrounds a circular hub  75 , shown in  FIG. 5 . The groove is designed for receiving the hose or tube of the pump in a manner described more fully below. Each sheave  70 ,  72  is fastened to a respective one of the side walls  24  by a nut/bolt connector  78 . As best shown in  FIGS. 2-4 , the mounting sheaves  70 ,  72  are supported slightly above the feet  13  of the pump and therefore slightly above the underlying table or supportive surface. 
     Each side wall  24  also carries a tube retainer element  80 , which is secured to the side wall  24  of support section  12  proximate and slightly above a respective one of the mounting sheaves  70 ,  72 . Each retainer element includes a bolt that is engaged with the corresponding hole in side wall  24 , a bushing  84  (best shown in  FIG. 5 ), which is disposed about bolt  82  and a fastening nut  86  that is attached to the distal end of the bolt adjacent bushing  84 . As is described more fully below, the retaining elements  80  work in cooperation with mounting sheaves  70 ,  72  to hold the pumping tube securely, yet releasably, in place during operation of the peristaltic pump. 
     An elongate, resilient peristaltic pumping hose or tube  90  is employed by the pump to conduct liquid therethrough. Tube  90  is composed of a durable and resilient tubing, which is commonly referred to as “stretch tube”. This is contrasted with “relaxed” tubing, which is universally utilized in low volume peristaltic pumps of the prior art. Preferably, Norprene™ is utilized for the tubing. This material is extremely resilient and durable. It provides for an extended and relatively maintenance free service life. Inlet and outlet fittings  91  and  93  are attached to the respective ends of tube  90  for attaching the tube to other segments of hose or other types of conduits or containers. 
     More particularly, tube  90  includes a leading tube segment  92  and a trailing tube segment  94 . An intermediate tube segment  96  is formed between leading and trailing segments  92  and  94 . Leading tube segment  92  is releasably interengaged with first sheave  70  in the manner best shown in  FIGS. 1-4 . In particular, segment  92  wraps about sheave  72  and is received by circumferential groove  76  in sheave  72 . Tube segment  92  extends through groove  76  and passes between sheave  72  and retainer element  80  before exiting the groove. Similarly, trailing segment  94  of tube  90  wraps about first mounting sheave  70  and extends between that sheave and its respective retainer element  80 , in the manner best shown in  FIG. 2 . The tube then extends through the circumferential groove of sheave  70  and exits the groove in a generally vertical direction. Intermediate segment  96  of tube  90  extends above and across cam rollers  40  in the manner best shown in  FIG. 1 . Tube  90  extends downwardly from rollers  40  such that leading tube segment  92  engages circumferential groove  76  of mounting sheave  72 , whereas trailing tube segment  94  engages the circumferential groove of sheave  70 . A snug frictional fit is provided between each resilient tube segment  92 ,  94  and the circumferential groove  76  of its respective mounting sheave. The mounting sheaves hold the leading and trailing ends of the tube securely in place and the tube is retained in snug interengagement with the sheaves by respective retainer elements  80 . 
     With the tube  90  assembled on pump  10  in the manner shown in  FIGS. 1-4 , pump  10  is ready to perform low volume peristaltic pumping in the manner illustrated in  FIGS. 3 and 4 . In particular, the inlet and outlet fittings  91  and  93  are interconnected to appropriate upstream and downstream conduits, containers, etc., which may be varied in accordance with the particular pumping application involved. It should be understood that alternative types of fittings or connections may be utilized in conjunction with tube  90 . The particular manner in which the tube attaches to or communicates with other conduits or containers is not a limitation of this invention. 
     It should be understood that a transparent plastic cover or housing may be attached to support section  12 , base  11 , casing  14  and/or sheaves  70 ,  72  for covering the rotor and tube during operation of the pump. Such a cover protects the working components of the pump. The particular structure of the cover and its means for attachment to the pump do not constitute part of the invention however. 
     Motor  16  is actuated by an appropriate electrical power source to operate drive mechanism  50 . In particular, rotary shaft  52  rotates in a clockwise manner to drive belt  60  and rotor  26  in the direction of arrow  66 . This turns cam roller components  40  with the rotor, as depicted in  FIGS. 3 and 4 . Cam rollers  40  engage intermediate section  96  of tube  90  such that peristaltic-type pumping in the direction of arrows  100  is performed in a generally conventional manner. In particular, when pressure is applied by a roller to the tube, the liquid is urged forwardly. By the same token, when roller pressure on the tube is relieved, a vacuum is created, which continues to push liquid forwardly. Liquid is pumped through intermediate tube segment  96  from trailing tube segment  94  to leading tube segment  92 . From there, the liquid is pumped to its eventual destination. 
     Tube  90  may be installed in and removed from pump  10 , as required, in an extremely quick and convenient manner. Initially, as shown in  FIG. 6 , operator  0  attaches tube  90  at its respective end segments to sheaves  70  and  72  by simply grasping a respective end segment of the tube (e.g. segment  92  in  FIG. 6 ) and wrapping the tube segment about the sheave such that the tube segment is received in circumferential groove  76 . The tube segment is then squeezed and inserted between the sheave and its associated retainer element  80  such that it is held securely in place as depicted in  FIGS. 1-4 . The end of the tube and its attached fitting may then be oriented in any desired direction and attached to a desired conduit or container. Hose  90  may be engaged with (e.g. extended above and across) cam rollers  40  either before or after the leading and trailing tube segments are securely engaged with their respective mounting sheaves  70  and  72 . 
     It is similarly easy to remove hose  90  from the pump when the hose needs to be inspected, cleaned and/or replaced. Operator  0  simply grasps one end of tube  90  and pulls either leading or trailing segment of the tube from between a respective sheave  70 ,  72  and its associated retainer element  80 . The distance between the sheave and the retainer element should be slightly less than the normal diameter of the tube so that the tube is held snugly and securely in place between the sheave and the retainer element. By the same token, the distance between each sheave and its associated retainer element should be wide enough so that the resiliently flexible tube is readily inserted into or removed from between the sheave and retainer element without requiring undue manual force or pressure. The resilient composition of the tube further facilitates such insertion and removal. 
     Accordingly, the present invention allows for the tubing or hose of a low volume peristaltic pump to be installed in or removed from the pump in a manner that is faster, easier and less annoying than has been heretofore possible in conventional peristaltic pumps. No clamps, clips or brackets must be unfastened and refastened to perform the tube changing operation. Maintenance of the peristaltic pump is therefore simplified and facilitated. By using a quick connect mounting sheave and resilient Norprene™ pumping tube of this invention, an easily serviceable, relatively maintenance free and long-lasting peristaltic pump is provided. 
     From the foregoing it may be seen that the apparatus of this invention provides for an improved peristaltic pump and, in particular, to a peristaltic pump utilizing a resiliently flexible fluid conducting tube that is releasably attached to a pair of “quick connect” mounting sheaves. While this detailed description has set forth particularly preferred embodiments of the apparatus of this invention, numerous modifications and variations of the structure of this invention, all within the scope of the invention, will readily occur to those skilled in the art. Accordingly, it is understood that this description is illustrative only of the principles of the invention and is not limitative thereof. 
     Although specific features of the invention are shown in some of the drawings and not others, this is for convenience only, as each feature may be combined with any and all of the other features in accordance with this invention. 
     Other embodiments will occur to those skilled in the art and are within the following claims: