Abstract:
A peristaltic pump, for propelling liquid through a flexible pump tube, includes an outer casing having a guiding channel wherein an operating portion of the pump tube extends along the guiding channel. The peristaltic pump further includes at least two pressuring rollers supported at the outer casing in a radially movable manner which can move outwardly to press against the operating portion of the pump tube. A center driving mechanism is supported at a center portion of the outer casing to radially push the pressure rollers and to drive the pressuring rollers to concurrently rotate such that the pressuring rollers roll against the operating portion of the pump tube for continuously propelling the fluid in the pump tube in the direction of rotation.

Description:
BACKGROUND OF THE PRESENT INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The present invention relates to a pump for propelling liquid through a flexible tube segment, and more particularly to a peristaltic pump for propelling liquid through the flexible tube in a concealed manner to ensure the purity of the liquid during transmission and to prevent an environmental pollution of the peristaltic pump.  
         [0003]     2. Description of Related Arts  
         [0004]     The peristaltic pump is commonly used as a safe and stable liquid pumping device in many different fields such as the medical, pharmaceutical, chemical, nuclear, aviation, and environmental industries.  
         [0005]     Nowadays, conventional peristaltic pumps usually comprise an outer casing, a flexible pump tube which is adapted for allowing fluid to flow therealong, a plurality of rotating rollers spacedly supported at the outer casing at equal radial distance. The rotating rollers exert pressure on the pump tube thus to propel the liquid. A negative pressure will then be formed when the pump tube returns to it normal position so ask to suck in fluid from the source and thus continuously propel the fluid to travel in the pump tube. There are many disadvantages for such a conventional peristaltic pump. For examples, the peristaltic pump enclosed in China Patent CN85204827 and CN87107936 uses the rotating rollers to only exert pressure on the pump tube in a particular arc section of the guiding channel so as to achieve a more convenient installation of the pump tube. As a result, the design will experience a radial pulsing force on a particular section of the pump tube and also faces the following problems that are hard to overcome:  
         [0006]     1. a high power motor is required to drive the machine to overcome the friction on the particular side, especially for the initial force and the torque, therefore it increases the size of the machine, i.e. the bigger size of driving shaft and the power of the motor, and the design has a low efficiency;  
         [0007]     2. the machine is easy to wear out, a special design is needed to suit for the machine in order to keep a desired pressure and displacement exerted by the rollers on the pump tube; and  
         [0008]     3. the machine is noisy.  
       SUMMARY OF THE PRESENT INVENTION  
       [0009]     The technical problem that the present invention seeks to solve is to provide a peristaltic pump that is accurate in pumping fluid, cost efficient, low manufactory cost, convenient to repair and minimize the noise level of the machine.  
         [0010]     Accordingly, in order to solve the above technical problems, the present invention provides a peristaltic pump comprises an outer casing that has at least one guiding channel, at least one flexible pump tube installed inside the guiding channel, at least two pressuring rollers which is driven by a center driving mechanism. The pump tube has an operating portion and circulates the guiding channel more than one full circle. The pressuring rollers are supported at the circular edge of the center driving mechanism and are driven by the center driving mechanism to rotate and exert pressure on the operating portion of the pump tube thus pumping the fluid along the pump tube.  
         [0011]     As an embodiment of the present invention, the center driving mechanism comprises a driving shaft capable of rotating to drive the pressuring rollers, a retainer which is used to retain and support the pressuring rollers, at least a driving plate which can rotate as the same manner as the driving shaft, and a plurality of peripheral indentions formed on outer edges of the driving plates so that the pressuring rollers can be received at the peripheral indention.  
         [0012]     According to the present invention, the retainer comprises at least one pedal. A pedal slot is formed at one of the driving plates as a starting plate that the pedal is engaged with the pedal slot. The center driving mechanism comprises at least two driving plates including the starting plate, preferably three or above. The number of the driving plates excluding the starting plate should preferably come in pairs so as to keep symmetry of the center driving mechanism. Accordingly, the center driving mechanism can be constructed to have a plurality set of driving plates that one set of the driving plates is formed as the starting plate. The starting plate can be a single plate structure and should be positioned at the center between other driving plates. The thickness of the single starting plate could be double the thickness of the other driving plates. The pedal slot of the starting plate matches the size of the pedal. The pedal slots of the other driving plates extends along it arc length which is adapted to be driven by the pedal in a predetermined order of the driving plates. A corner of the peripheral indention of the starting plate can be formed in a roundness manner to the outer diameter by making the edge tangent to the outer diameter such that the edge of the peripheral indention is smoothly and gradually extended from the bottom side of the peripheral indention to the outer edge of the starting plate.  
         [0013]     In addition, the retainer is used to the distance between the pressuring rollers. The retainer further comprises a retainer shaft protrudes out from two sides of the pressuring roller and engages within a retainer slot of the retainer so that the pressuring roller can be supported firmly and its distance between the pump tube and the driving plates can be retained.  
         [0014]     The total thickness of the driving plates should be equal to the length of the pressuring roller and is approximate two times the width of the compressed pump tube. The peripheral indentions are equally spacedly installed at the outer edges of the driving plates and have a corresponding pressuring roller to engage with. The depth and shape of the aligned peripheral indentions of the driving plates should correspond to diameter size of the pump tube so that the pump tube is allowed to recover to its original shape when the pressuring roller is engaged with the peripheral indention of the starting plate.  
         [0015]     The outer casing of the peristaltic pump can comprise a plurality of guiding channel wherein each guiding channel has one single pump tube. As an alternative, the outer casing of the peristaltic pump comprises only a single guiding channel but capable to have multiple pump tubes installed within.  
         [0016]     The advantage of the present invention is that the peristaltic pump has a full complete circle of propelling path for the pump tube to propel liquid. Since it is a full circle and the pressuring rollers are evenly distributed all around, the force of the pressuring rollers can couple with each other and thus minimize the problem of getting a single stressed area in the peristaltic pump. The pressure exerted on the pump tube are also evenly distributed along the full circle thus to provide a more accurate and stable propelling motion. The present invention can minimize the noise as well as manufacturing and repairing cost of the peristaltic pump. When the peristaltic pump is not in used, the pressuring rollers can receive in the peripheral indention so that the pump tube will not be receiving unnecessary pressure. And the design makes the installation and tuning of the pump tube easier and is suitable for various types of pump tubes.  
         [0017]     A main object of the present invention is to provide a peristaltic pump for propelling liquid through a flexible tube segment which is very stable and accurate in propelling liquid while the noise from the peristaltic pump can be minimized.  
         [0018]     Another object of the present invention is to provide a peristaltic pump for propelling liquid through a flexible tube segment which is very energy efficient. Another object of the present invention is to provide a peristaltic pump for propelling liquid through a flexible tube segment without exerting pressure on the tube when installing the tube into the peristaltic pump in the beginning of the operation so as to simplify the operation of peristaltic pump and to prevent pump tube being aged when the pressure continuously exerts at the pump tube while being unused.  
         [0019]     Another object of the present invention is to provide a peristaltic pump for propelling liquid through a flexible tube segment which does not involve complicated mechanical structure, so as to minimize the manufacturing and repairing cost of the peristaltic pump.  
         [0020]     Another object of the present invention is to provide a peristaltic pump for propelling liquid through a flexible tube segment which minimizes the noise effectively.  
         [0021]     Accordingly, in order to accomplish the above objects, the present invention provides a peristaltic pump for propelling liquid through a flexible tube segment comprising:  
         [0022]     an outer casing having a guiding channel and defining a circular path therealong;  
         [0023]     a flexible pump tube, which is adapted for allowing the liquid flowing therealong, having an operating portion extending along the guiding channel of the outer casing;  
         [0024]     at least two pressuring rollers spacedly and eccentrically supported at the outer casing in a radially movable manner; wherein the two pressuring rollers are radially and outwardly moved to press against the operating portion of the pump tube along the circular path;  
         [0025]     a center driving mechanism supported at a center portion of the outer casing to radially push the pressure rollers and to drive the pressuring rollers to concurrently rotate such that the pressuring rollers roll against the operating portion of the pump tube for continuously propelling the fluid in the pump tube in the direction of rotation.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a top sectional view of the peristaltic pump according to a preferred embodiment of the present invention.  
         [0027]      FIG. 2  is a side sectional view of the peristaltic pump according to the above preferred embodiment of the present invention.  
         [0028]      FIG. 3  is a front view of the driving plate of the transmission unit according to the above preferred embodiment of the present invention illustrating their peripheral indention and pedal slots.  
         [0029]      FIG. 4  illustrates an alternative mode of the starting plate according to the above preferred embodiment of the present invention.  
         [0030]      FIG. 5  illustrates a configuration of the present invention using two pump tubes.  
         [0031]      FIG. 6  illustrates a configuration of the present invention using three pump tubes.  
         [0032]      FIG. 7  illustrates another alternative of the present invention which the driving plate has two pedal slots.  
         [0033]      FIG. 8  is a side view of the outer casing illustrating that it is divided into the upper layer and the lower layer and is capable of rotating for ease of tuning and installation.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0034]     Referring to  FIG. 1  and  FIG. 2  of the drawings, the peristaltic pump comprises an outer casing  10 , a center driving mechanism, at least two pressuring rollers  40 , a retainer  60 , and a flexible pump tube  90 . The outer casing  10  has a guiding channel  12  formed along an inner wall of the outer casing  10  and defines a circular path therealong, a center driving mechanism supported at a center portion of the outer casing  10 . There are pressuring rollers  40  spacedly and eccentrically supported at the outer casing  10 . The retainer  60  is used to retain and support the pressuring roller  40 . The flexible pump tube  90  made of silicon, which is adapted for allowing the liquid flowing therealong, has an operating portion extending along the guiding channel  12  of the outer casing  10 . Accordingly, the pressuring rollers  40  are symmetrically and planetary supported at the outer casing in a radially movable manner. The center driving mechanism comprises a motor which drives a driving shaft  20 . A transmission unit  30  comprises a cylindrical driving element, wherein a pedal  33  protrudes out from an outer surface of the driving element, and a plurality of driving plates  501 ,  502 ,  503 ,  504 , and  505  in an overlapped manner. According to the preferred embodiment of the present invention, there are five driving plates  501 - 505 .  
         [0035]     Referring to  FIG. 3  of the drawings of the preferred embodiment, the first to fifth driving plates  501 - 505  are very similar in a circular structure. The third driving plate  503 , which is also regarded as a middle starting plate, has three peripheral indentions  5033  in an arc shape evenly formed at the circumferential edge of the third driving plate  503 . The center portion of the third driving plate  503  has a pedal slot  5035 . The third driving plate  503  has a predetermined diameter that the third driving plate  503  is adapted to push the pressuring roller  40  to substantially press against the pump tube  90  within the guiding channel  12 . The depth and shape of the peripheral indention  5033  of the third driving plate  503  should correspond to diameter size of the pump tube  90  so that the pump tube  90  is allowed to recover to its original shape when the pressuring roller  40  is engaged with the peripheral indention  5033  of the third driving plate  503 . In other words, the radius of the peripheral indention  5033  is slightly larger than the radius of the pressuring roller  40  so as to allow the pump tube  90  not being pressed within the guiding channel  12  when the pressuring roller  40  is located at the peripheral indention  5033 . Accordingly, all five driving plates  501 - 505  have the same structure of the peripheral indentions. The difference between the five driving plates  501 - 505  is the size of the pedal slot. The arc length of the pedal slot  5035  of the third driving plate  503  is the same arc length of the pedal  33  such that the pedal  33  can be fitted into the pedal slot  5035  of the third driving plate  503 . In other words, the size and the shape of the pedal  33  of the transmission unit  30  is fitted right into pedal slot  5035  of the driving plate  503 . The third driving plate  503  is sandwiched between the identical second and fourth driving plates  502 ,  504 , wherein the arc length of the pedal slot  5025 ,  5045  of each of the second and fourth driving plates  502 ,  504  is larger than the arc length of the pedal slot  5035  of the third driving plate  503 . Preferably, arc length of the pedal slot  5025 ,  5045  of each of the second and fourth driving plates  502 ,  504  is additional 40° of the arc length of the pedal slot  5035  of the third driving plate  503 . In other words, the arc length of the pedal slot  5025 ,  5045  of each of the second and fourth driving plates  502 ,  504  is additional 40° extending at the operation direction, i.e. the rotational direction of each of the second and fourth driving plates  502 ,  504 . The second, third, and fourth driving plates  502 ,  503 ,  504  are sandwiched between the identical first and fifth driving plates  501 ,  505 . In other words, the first and fifth driving plates  501 ,  505  are the two outer plates. The arc length of the pedal slot  5015 ,  5055  of each of the first and fifth driving plates  501 ,  505  is larger than the arc length of the pedal slot  5025 ,  5045  of each of the second and fourth driving plates  502 ,  504 . Preferably, arc length of the pedal slot  5015 ,  5055  of each of the first and fifth driving plates  501 ,  505  is additional 80° of the arc length of the pedal slot  5035  of the third driving plate  503 . In other words, the arc length of the pedal slot  5015 ,  5055  of each of the first and fifth driving plates  501 ,  505  is 80° extending at the operation direction, i.e. the rotational direction of each of the first and fifth driving plates  501 ,  505 .  
         [0036]     The transmission unit  30  is connected to the driving shaft  20 . The driving plates  501 - 505  are overlappedly combined together to engage with the transmission unit  30  that the pedal slots  5015 ,  5025 ,  5035 ,  5045 , and  5055  are coaxially aligned with each other. The pedal  33  of the driving element engages the pedal slots  5015 ,  5025 ,  5035 ,  5045 ,  5055  of the driving plates  501 - 505  such that when the driving element is driven to rotate by the driving shaft  20 , the driving plates  501 - 505  are driven to rotate subsequently by the pedal  33 .  
         [0037]     The peripheral indentions as shown in  FIG. 3  all have sharp corners.  FIG. 4  illustrates an alternative mode of the peripheral indention wherein a corner of the peripheral indention  5033  of the third driving plate  503  can be modified as a round corner as shown by the dotted line which tangents out with the outer diameter of the driving plate  503 . The second and third driving plates  502   504  can follow the same modification as the third driving plate  503  to minimize the clearance of the driving plates  501 - 505  when the peripheral indentions of the driving plates  501 - 505  are misaligned to form an arc surface. This modification does not affect the operation of the invention. All driving plates  501 - 505  have the same thickness which their combined thickness is equal to the width of the pressuring roller  40  and is approximately equal to two times of the width of the pressured pump tube  90 .  
         [0038]     The pressuring roller  40  has a diameter of approximately 2.5-3 times of the depth of the pump tube  90  needed to be compressed. A width of the pressure roller  40  is approximately two times of the width of the compressed pump tube  90 . A retainer shaft  44  protrudes out from two sides of the pressuring roller  40  and engages within a retainer slot  66  of the retainer  60  so that the pressuring roller  40  can be supported firmly and its distance between the pump tube  90  and the driving plates  501 - 505  can be retained.  
         [0039]     According to the preferred embodiment of the present invention, the retainer  60  also helps to keep a predetermined distance between the pressuring rollers  40  but it does not affect the rotation and radial movement of them. Accordingly, a movable connecting rod can be installed in between the pressuring roller  40  and the retainer  60 . A central axis of both sides of the pressuring roller  40  can be connected to an end of the connecting rod. This structural configuration does not affect the operation of the invention also.  
         [0040]     The outer casing  10  has the guiding channel  12  formed along the inner side of the peripheral wall of the outer casing  10  and defines the circular path therealong. According to the preferred embodiment of the present invention, the pump tube  90  is installed in a full spiral manner in the guiding channel  12  of the outer casing  10 . An installation space is required for inserting the pump tube  90  into the guiding channel  12  of the outer casing  10 . In other words, a width of the guiding channel  12  is approximately about two times the width of the compressed pump tube  90  when the pump tube  90  is pressed by the pressuring roller  40  along the guiding channel  12 . Furthermore, the pump tube  90  is tangentially extended into the outer casing  10  at an entrance of the guiding channel  12  until the operating portion of the pump tube  90  is received along the circular path of the guiding channel  12 . In addition, the operating portion of the pump tube  90  is retained in an arc shape within the guiding channel  12  while the guiding portion of the pump tube  90 , i.e. extending from the operating portion thereof, is tangentially extended with respect to the outer casing  10 . Therefore, the configuration of the pump tube  90  with respect to the outer casing  10  allows the liquid to flow in a maximized circular distance with respect to the circumference of the outer casing  10  such that when the pressuring rollers  40  substantially press against the pump tube  90 , the liquid is forced to flow along the arc-shaped operating portion of the pump tube  90  within the circular path at 120° so as to cancel the pulsation of the liquid within the pump tube  90 .  
         [0041]     If the peripheral wall of the outer casing  10  is too slippery, then the pump tube  90  might have a slight movement along the guiding channel  12  while in operation. A plate can be installed at an entrance or exit location of the pump tube  90  in the peripheral wall to limit the slight movement of the pump tube  90  along the guiding channel  12 . As an alternative, the peripheral wall of the guiding channel  12  can be formed as a rough surface to enhance the friction of the pump tube  90  against the peripheral wall so as to avoid the movement along the guiding channel  12 .  
         [0042]     The operation principle of the present invention is explained below in detail:  
         [0043]     In a release state when the driving shaft  20  is not rotating, the peripheral indentions of the all driving plates  501 - 505  are all aligned to each other so that a full arc indention surface is formed at the peripheral side of the combined driving plates  501 - 505 . The pressuring roller  40  can then be fitted to engage the peripheral indentions of the driving plates  501 - 505  at a position that the circumferential surface of the pressuring roller  40  is engaged with the indention surface of the driving plates  501 - 505 . The pump tube  90  can be installed now and there will not be any pressure exerted onto the operating portion of the pump tube  90 . When the driving shaft  20  starts to rotate in the operating direction, it will drive the transmission unit  30  to rotate as well. The pedal  33  of the driving element of the transmission unit  30  will first engage the pedal slot  5035  of the driving plate  503  because the pedal slot  5035  is the narrowest out of the five driving plates  501 - 505  and thus drive the driving plate  503  to rotate in the operating direction as well. Once this motion starts, the peripheral indentions  5033  of the driving plates  501 - 505  will not be aligned to each other forming a full arc shape and thus disengage the peripheral indentions of the driving plates  501 - 505  from the pressuring roller  40 . At this point, the pressuring roller  40  is then forced to radially extend towards the peripheral wall of the outer casing  10  and thus exerts a pressure on the pump tube  90 . When the driving shaft  20  reaches a 40° rotation in the operating direction, the pedal  33  of the driving element of the transmission unit  30  will then engage the pedal slots  5025 ,  5045  of the second and fourth driving plates  502 ,  504  and thus drive the second and fourth driving plates  502 ,  504  to rotate. When the driving shaft  20  rotates an extra  400  in the operating direction, the pedal  33  of the driving element of the transmission unit  30  will then engage the pedal slots  5015 ,  5055  of the first and fifth driving plates  501 ,  505  and thus drive the first and fifth driving plates  501 ,  505  to rotate. At this moment, the peripheral indentions of each of the driving plates  501 - 505  will not be aligned and thus no indention or arc will be formed from the combined driving plate  501 - 505 . Therefore, as long as the driving shaft  20  keeps rotating in the operating direction or does not rotating in a reverse direction until a predetermined degree of rotation, the peripheral indentions of the driving plates  501 - 505  will never be aligned with each other, thus the pressuring roller  40  will always be exerting pressure onto the operating portion of the pump tube  90 . Following the procedure above, the fluid in the pump tube  90  will be forced to be pumped thus fulfilling to role of the peristaltic pump. When the machine is not in use, rotate the driving shaft  20  in the reverse direction less than 180° and the peripheral indentions of the driving plates  501 - 505  will be aligned on top with each other again. Since the pump tube  90  itself is flexible and elastic in it self-nature, it will push back onto the pressuring roller  40  and thus forcing the pressuring roller to engage the aligned peripheral indentions of the driving plates  501 - 505  and the present invention to return to the release state.  
         [0044]     Referring to  FIG. 2  of the drawings, the outer casing  10  further comprises an opening cover  80  which can be opened so as to make ease for the removal of the pump tube  90  and the center driving mechanism for repairing and such.  
         [0045]     Referring to  FIG. 5  and  FIG. 6  of the drawings, using the same principle for operating the present invention, multiple pump tubes  90  can be used in the present invention. The pump tubes  90  can be installed inside the guiding channel  12  of the outer casing  10  in a similar manner as described above. Multiple pump tubes  90  can be used as long as the pump tubes  90  are installed in a full circle manner around the peristaltic pump and have at least one of the pressuring rollers to be exerting pressure on the operating portion of the pump tube  90 .  FIG. 5  illustrates a configuration of the present invention using two pump tubes  90 .  FIG. 6  illustrates a configuration of the present invention using three pump tubes  90 . Using the same principle for operating the present invention, for example, a combined total number of 3 and 7 pieces of driving plates will also work in the same manner as described in the preferred embodiment as well as long as they are symmetrically installed on each sides of the driving plate in the middle. It is even possible to use only two driving plates to carry out the function of a five pieces driving plates  501 - 505  as described in the preferred embodiment. Thus, the driving plates  501 - 505  of the transmission unit  30  are not limited by their numbers as long as an angle of the pedal slot of the driving plate correlates to a desired situation.  
         [0046]     Referring to  FIG. 7  of the drawings, an alternative of the driving plates  501 - 505  of the present invention is illustrated. Using the driving plate  503  as example, the pedal slot  5035  can have a duplicated exact mirror feature of itself by rotating  1800 . Therefore the pedal slot  5035  of the driving plate  503  is now double-sided. A similar principle modification is applied to the pedal  33  of the driving element of the transmission unit  30  so as to increase the contact area between the pedal  33  and pedal slot  5035  and thus creates a more stable and efficient rotation of the transmission unit  33 .  
         [0047]     Referring to the preferred embodiment of the present invention, the pressuring roller  40  and the drifting shaft  20  are made of metallic materials. Other parts are made of plexiglass. The peripheral wall of the guiding channel  12  of the outer casing  10  is lathed in a single cut from a two layer plexiglass. The entrance and exit location of the pump tube  90  can be milled from a milling machine and then the opening cover  80  of the outer casing  10  can be installed firmly thereon by screws.  
         [0048]     Referring to  FIG. 8  of the drawings, the present invention can also be produced in mass production by a casting of industrial plastic and similar materials. The outer casing  10  can be split into an upper housing  17  and a lower housing  18 . In between the upper housing  17  and lower housing  18 , an edge  15  is defined at a joint area so that the upper housing  17  can be fittedly received inside the lower housing  18  and screws can be used to joint them. Since multiple pump tubes  90  or different brand or material of pump tubes  90  can be used in the present invention, the flexible pump tube  90  can reflect a different pressure back on the pressuring roller  40 . The upper housing  17  and the lower housing  18  can now rotate concentrically in an independent manner so as to offer an option for tuning the angles or a routing route of installing pump tubes  90  into the guiding channel  12  of the outer casing  10 .