Abstract:
A vibratory pump includes an oscillator that is connected to a plunger mounted within a housing submerged beneath the surface of a fluid to be displaced. The oscillations of the plunger selectively communicate an outlet for the pump with inlet openings on the housing. The selective communication creates a slight vacuum in the pump that enables the fluid to be moved by the pump without generating any significant back pressure in the outlet fluid flow from the pump. The pump can also be configured to operate in a dual stroke mode where an outward flow of fluid from the pump is generated during both the downward and return strokes of the pump.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to pumps, and in particular to a vibratory pump that can be widely used in different branches of industry, in scientific research, in medicine and in agriculture production. 
     When fluids are to be moved from one place or container to another, a pump is normnally used. The wide variety of pumps available can very adequately move the fluid using mechanical forces generated by the pump. However, these pumps cannot adequately move precise volumes of fluid due the presence of back pressure in the fluid lines of the pump. This back pressure is created by the force of the fluid flowing through the pump, and causes the fluid being pumped to continue to flow for a period of time after the pump has stopped operating. 
     Therefore it is desirable to develop a type of pump which is capable of moving large volumes of fluid from one location to another without creating any back pressure within the pump itself. A pump having this capability would be highly useful in situations where the volume of fluid to be moved must be extremely precise, such as in various medical applications. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a pump operated by a vibration generator that does mot create any back pressure in the fluid flow when the pump is in operation. 
     It is another object of the invention to provide a pump which can deliver a fluid in a wide range of volumes by varying the frequency of the vibration generator driving the pump. 
     It is still another object of the invention to provide a pump that can provide a fluid flow out of the fluid lines of the pump during both the downward and upward strokes of the pump. 
     It is still a further object of the invention to provide a pump capable of combining the fluid flow generated during both strokes of the pump into a single fluid flow. 
     The present invention is a pump operated by a vibration generator connected to the pump. The pump includes a plunger slidably disposed within a housing having a number of fluid openings. The fluid openings allow the fluid to be pumped to enter the interior of the housing. A shaft connects the plunger to the vibration generator to enable the pump to move in conjunction with the oscillations of the vibration generator. The vibration generator causes the shaft and plunger to move a short distance in order to create the pumping action for the apparatus. 
     The plunger is in fluid communication with an outlet on the housing and also includes a number of fluid openings that enable the fluid entering the housing to flow into the plunger. The oscillation of the plunger within the housing successively fills the plunger with fluid and forces the fluid out of the outlet of the housing. 
     The small travel length of the plunger in the housing creates no back pressure in the fluid passing through the pump. This enables the fluid flow generated by the pump to stop instantaneously with the shutting off of the pump. Furthermore, because the vibration generator is controlled by a variably operable power source, it is possible to change the output of the pump of the present invention over a wide range of operational parameters to control the flow rate based upon the particular application to which the pump is put. 
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
     FIG. 1 is a cross-sectional view of a pump apparatus constructed according to the present invention; and 
     FIG. 2 is a cross-sectional view similar to FIG. 1 of a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to the drawing figures in which like reference numerals designate like parts throughout the disclosure, a pump is designated generally at  1  in FIG.  1 . The pump  1  includes a pump body  1  a that encloses an electric motor  2  that is connected to a converting mechanism  3  which converts the rotary motion of the electric motor  2  into the reciprocating motion necessary for the operating elements of a vibratory pump. In a preferred embodiment the mechanism  3  is a circular cam, but can be any suitable device. The electric motor  2  is powered by a conventional power supply  4 , such as a DC or AC power source. The power supply  4  is connected to the motor  2  through an electronic current controller  5  which can be used to control the operating speed of the electric motor  2 , and consequently to control the frequency of the oscillations of the converting mechanism  3  connected to the motor  2 . 
     Opposite the motor  2 , the converting mechanism  3  is connected to the upper end of a shaft  6  which is disposed within a tube  7  interconnected with the body  1   a . The shaft  6  is formed of a rigid material such as a hard plastic or a metal, e.g., steel, aluminum, titanium, polyvinyl chloride, polyester, or any other suitable material. The tube  7  is fixed to the body  1   a  such that the shaft moves relative to the tube  7  when the pump  1  is in operation. 
     Opposite the body  1  a the tube  7  is fixedly connected to a housing  8 . The housing  8  is generally square in shape, but can have any form desired. The body  1   a , the tube  7  and the housing  8  are preferably formed of the same material, which is a rigid, waterproof material resistant to most acidic and basic substances to enable the pump  1  to pump corrosive fluids. 
     The housing  8  has an upper wall, a lower wall and a number of side walls, and includes a pair of openings  15  in opposed side walls of the housing  8 . The opening  15  allow fluid to enter into the interior of the housing. While the housing  8  is illustrated as having a pair of opposed openings  15 , it should be noted that the number of openings in the housing can be varied from as few as one, to as many as are deemed necessary to enable the proper amount of fluid to enter the housing. The lower wall of the housing  8  has an outlet opening  8 a in which is disposed a hollow cylindrical chamber  12 . The chamber  12  defines an outlet for the fluid that has entered the housing  8  and includes a peripheral flange  14  around an inlet end disposed within the housing  8 , and an outlet tube  13  forming an outlet end outside of the housing  8  opposite the flange  14 . The outlet tube  13  can be connected to a length of hose (not shown) in order to direct the outlet flow of fluid to the desired location. 
     The pump also includes a cylindrical plunger  10  disposed within the housing  8  and slidably engagable with the chamber  12 . The plunger  10  has an outer diameter slightly lees than the inner diameter of the chamber  12 , i.e. between 0.0 and 0.25 mm smaller, to allow the plunger to slide freely within the chamber  12 . The plunger  10  also has a closed upper end and an open lower end. The upper end is formed by a plate  9  extending across the upper end of the plunger and forming a peripheral flange around the upper end of the plunger  10 . The shaft  6  is secured to the plate  9  to enable the plunger  10  to move in conjunction with the oscillating movements of the shaft  6  and converting mechanism  3 . When the shaft  6  has raised the plunger  10  to its highest point within the housing  8 , the open end of the plunger  10  is positioned partially within the chamber  12 , at least 4 mm below the inlet end of the chamber  12 , to ensure that the plunger  10  remains in proper alignment with the chamber  12  while the pump  1  is in operation. 
     Between the plate  9  and the open end, the plunger  10  also includes a number of fluid passages  11  that enable the fluid inside the housing  8  to enter the plunger  10  when the plunger  10  is raised above the chamber  12 . When the plunger  10  is urged downwardly into the chamber  12 , the passages  11  are closed and the fluid is pushed out of the plunger  10  and into the chamber  12 . To sealingly engage the flange  14  on the chamber  12  when the plunger  10  is fully positioned within the chamber  12  and prevent fluid from flowing out of the chamber  12  past the plunger  10 , a sealing member  16 , such as a rubber O-ring, is positioned against the plate  9  to engage the flange  14  when the plunger  10  is fully inserted into the chamber  12 . 
     To operate the pump  1 , the housing  8  is placed within a volume of the fluid to be pumped. The power supply  4  is then switched on and the voltage is transmitted to the electronic voltage controller  5  which is connected to the electric motor  2 . The controller  5  makes it possible to control the revolutions of the motor  2  by controlling the voltage reaching the motor  2 . Typically, the motor  2  is operated in the range of from between ten (10) to one hundred and fifty (150) Hz. Any increase of the frequency of the oscillations of the cylinder  10  provides an increase of the volume output of the pump  1 . Also, an increase of head characteristics of the pump  1  can be provided by an increase of the length of the motion of the plunger  10 . 
     The rotation of the motor  2  is transferred to the converting mechanism  3  which changes the rotary motion of the electric motor into the reciprocating motion of the shaft  6 . The oscillations of the shaft  6 , in turn, urge the plunger  10  to move in a reciprocating fashion inside a chamber  12 . When the plunger  10  moves upwardly, the passage  11  is exposed and fluid contained within the housing  8  flows into the plunger  10  through the passage  11 . The plunger  10  is then urged downwardly into the chamber  12 . The length of the downward motion of the plunger  10  is slightly greater than the length of the passage  11  to ensure that the entire passage  11  is covered by the chamber  12 . As the passage  11  is covered by the chamber  12 , the fluid contained within the plunger  10  is directed into the chamber  12  and through the outlet end  13  for displacement. When the passage  11  is again exposed as the plunger  10  begins to move upwardly, a slight vacuum is formed within the plunger  10  by the absence of the fluid in the plunger  10  that causes more fluid to enter the plunger  10  through the passage  11 . The flanges  9  and  14  assist in the creation of an area of low pressure in the liquid surrounding the plunger  10  at the moment the passage  11  is first exposed. 
     This small vacuum and the weight of the fluid in the container are the only forces acting to create any back pressure in the pump  1 . As a result, the back pressure in the pump  1  is negligible, such that when the motor  2  or power source  4  is switched off, the flow of fluid through the outlet  13  ceases immediately. 
     A second embodiment of the pump  1 ′ of the present invention is presented in FIG.  2 . This second embodiment has a volume output capacity twice as large as the pump  1  of FIG. 1 due to the transformation of the return stroke of the plunger inside a fixed chamber into a working stroke. The pump  1  includes a housing  21  having an upper end and a lower end that has two sets of input holes  26  and  26 * through which fluid disposed around the housing  21  can flow into the interior of the housing  21 . 
     The housing  21  also has a pair of outlet openings disposed adjacent the up per end and at the lower end, respectively. Each outlet opening is connected to an inlet leg  210  and  211  of an outlet tube The inlet legs  210  and  211  are each connected to an outlet leg  212  and  213 , respectively, that are, in turn, connected to a collector  214  opposite the inlet legs. The collector  214  includes a fluid wedge  215  that diverts the outgoing fluid streams in each outlet leg  212  and  213  in such a manner as to greatly reduce the pressure of these fluid streams on one another. 
     To direct the fluid from the interior of the housing  21  into the outlet openings, a piston or plunger  23  is disposed within the housing  21 . The plunger  23  conforms to the shape of the housing  21  and has an outer diameter slightly less than the inner diameter of the housing  21 . This enables the plunger  23  to slide freely within the interior of the housing  21 . The plunger  23  is generally hollow and has a plate  217  extending across the inside of the plunger  23  at approximately the midpoint of the plunger  23  to define an upper cavity  218  and a lower cavity  219  on opposite sides of the plate  217 . 
     The plate  217  is also connected to one end of a shaft  24  disposed within the upper cavity  218 . The shaft  24  is connected to a converting mechanism (not shown) and motor (not shown) similar to that illustrated in FIG. 1 as is used to oscillate the plunger  23  within the housing  21 . The shaft  24  passes through a shaft opening in the housing  23  which is sealed by a sealing member  28  and plug  29  disposed around the shaft  24  above the housing  21 . The sealing member  28  is formed similarly to the O-rings described with respect to FIG.  1  and are enclosed with the plug  29  inside an enclosure  220  which enhances the sealing ability of the member  28  and plug  29 . 
     The plunger  23  also has a pair of sealing members  25  disposed within circumferential grooves opposite the plate  217  and adjacent each end of the plunger  23 . The members  25  are preferably rubber O-rings that serve to prevent any fluid from flowing between the inside of the hosing  21  and the outside of the plunger  23  while the pump  1 ′ is in operation. 
     The length of the plunger  23  is equal to the length between the lower edge of the upper set of openings  26  and the lower edge of the lower set of openings  26 * plus four (4) mm. Therefore, when the plunger  23  is positioned at the extremes of its oscillation, i.e., the top or bottom of the housing  21 , the plunger closes one set of openings  26  or  26 * and opens the opposite set. This allows fluid to flow into the portion of the housing  21  in fluid communication with the unobstructed openings, and prevents fluid from entering the remainder of the housing  21 . 
     In operation, the housing  21  is placed within a volume of fluid to be displaced and the motor and converting mechanism are turned on and cause the shaft  24  to oscillate up and down a predetermined distance. The oscillation of the shaft  24  also causes the plunger  23  to oscillate the same distance within the housing  21 . At the highest point in the oscillation, the plunger  23  completely obstructs the upper set of openings  26  and completely opens the lower set  26 *. This allows the fluid surrounding the housing  21  to enter into the interior of the housing  21  through the openings  26 * and fill the lower cavity  219 . When the plunger  23  begins to move downwardly in response to the oscillation of the shaft  24 , the fluid contained within the cavity  219  is urged outwardly from the housing  21  into the inlet leg  210  at the bottom of the housing  21 . Simultaneously, the openings  26 * are closed and the openings  26  are opened by the plunger  23 . This prevents any more fluid from entering the lower cavity  219  and creates a small vacuum around the openings  26  such that fluid enters and fills the upper cavity  218 . The plunger  23  then moves upwardly, urging the fluid filling the upper cavity  218  out of the housing  21  and into the inlet leg  211 . The upward movement of the plunger  23  also closes the openings  26  and opens the openings  26 * to create a small vacuum around the opening  26 * and again fill the lower cavity  219 , as occurred previously. The oscillation of the plunger  23  within the housing continually opens and closes the respective openings  26  and  26 * to provide an outward flow of fluid regardless of the direction in which the plunger  23  is moving, effectively doubling the volume output for the pump  1 ′. 
     Similar to the first embodiment, the head capacity and flow rate characteristics of the pump  1 ′ can be controlled by controlling the frequency of the oscillations for the plunger and the length of its working stroke. These characteristics can also be altered by changing the overall dimension of the operating elements of the pump  1 ′ or the power characteristics of the electric motor and/or oscillator, such as by changing the voltage supplied to the motor. Furthermore, as with the first embodiment, only the small vacuum and the weight of the fluid create any back pressure on the output fluid flow, which is negligible. 
     Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.