Abstract:
A configuration of a tubing pump capable of improving flow rate accuracy which is required, particularly, in infusion pumps for medical use is developed. In a tubing pump that delivers a liquid in a tube which is separately loaded, a pump mechanism includes a valve mechanism unit that occludes and releases occlusion to the loaded tube and a tube pressing mechanism unit that repeatedly presses the tube, and the tube squeezing mechanism unit includes a pump block which has its movement guided by at least two guide shafts.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a tubing pump that is primarily used as an infusion pump for medical use and that delivers fluid in a tube, which is separately loaded into a pumping mechanism. 
         [0003]    2. Description of the Related Art 
         [0004]    In the related art, infusion pumps for medical use include a reciprocating type infusion pump in which a tube is loaded between two V-grooves and is repeatedly pressed by a reciprocation of any one of the two V-grooves. 
         [0005]    As an example of the reciprocating type infusion pump, Patent Document  1  discloses a reciprocating type infusion pump in which a tube is loaded between a V-groove formed by an upper jaw  220 , a lower jaw  222  and a V-groove of a shuttle  200  and is repeatedly pressed by a reciprocation of the shuttle  200 . 
         [0006]    In the infusion pump disclosed in Patent Document 1, an upstream valve  412  is positioned on the upstream side of the shuttle  200 , and a downstream valve  414  is positioned on the downstream side thereof. 
         [0007]    The upstream valve  412  and the downstream valve  414  occlude a tube or open the tube at an appropriate timing in association with the reciprocation of the shuttle  200 , and thus, fluid in the infusion tube is transferred. 
         [0008]    Operational ranges of the shuttle  200 , the upstream valve  412 , and the downstream valve  414  are defined by a cam  100  with cam profiles that define the operational of the shuttle  200 , the upstream valve  412 , and the downstream valve  414 . 
         [0009]    Another example of a reciprocating type infusion pump, Patent Document  2  discloses a reciprocating type infusion pump in which a tube is loaded between a V-groove of a V-groove-shaped fixed component  22  and a V-groove-shaped driving component  12 A and is repeatedly pressed by the reciprocation action of the V-groove-shaped driving component 12A. 
         [0010]    The reciprocating type infusion pumps as disclosed in Patent Document 1 and Patent Document 2 produce an accurate flow rate accuracy as compared with, for example, a peristaltic-type infusion pump disclosed in Patent Document 3 in which an tube is pressed by peristalsis of all of a plurality of fingers. 
         [0011]    However, further improvement of flow rate accuracy, particularly in infusion pumps for medical use is required. 
         [0012]    (Patent Document 1) Japanese Laid-Open Patent Publication No. hei 11-508017 
         [0013]    (Patent Document 2) International Patent Publication No. WO2009/133705 
         [0014]    (Patent Document 3) Japanese Laid-Open Patent Publication No. hei 5-277183 
       SUMMARY OF THE INVENTION 
       [0015]    According to an aspect of the present invention, there is provided a tubing pump that delivers fluid in a tube, which is separately loaded into a pump mechanism. The pump mechanism includes: a valve mechanism unit that occluded and opens the loaded tube, and a tube pressing mechanism unit that repeatedly presses the tube, the tube pressing mechanism unit included a pump block that is movable along at least two guided shafts, and the tube being is repeatedly pressed by a continuous reciprocation of the pump block. 
         [0016]    According to the above configuration, since the movement of the driving unit can be prevented, fluid in a tube may be transferred at further stable flow rate accuracy. 
         [0017]    In another aspect of this present invention, the tube pressing mechanism unit consist of a front facing component which does not move when delivering the liquid in the tube, the front facing component is being assembled at a position directly opposite to the pump block. The first groove profile with an approximate V shape is formed in the pump block. The second groove profile having an approximately V shape is formed in the front facing component. The tube is repeatedly pressed between the first groove profile and the second groove profile when the pump block reciprocates continuously. 
         [0018]    According to the above configuration that allows the process of repeatedly pressing the tube, the deformation state of the tube from squeezing the tube may be restored before the tube is pressed again, thus, the liquid in the tube may be transferred at an accurate flow rate. 
         [0019]    According to another aspect of the present invention, the valve mechanism unit is positioned on the upstream side and the downstream side. The tube pressing mechanism unit is positioned between the valve mechanism unit on the upstream side and the valve mechanism unit on the downstream side. The operational range of the pump block assembled in the tube pressing mechanism unit is determined by a pump cam. The operational range of the upstream side valve of the valve mechanism unit is determined by a first valve cam. The operational range of a downstream side valve of the valve mechanism unit is determined by a second valve cam. The pump cam, the first valve cam, and the second valve cam are different cam components to each other. 
         [0020]    According to the above configuration, the opening and closing timings of the valve may be setup further to deliver fluid at an accurate flow rate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0022]      FIG. 1  is a perspective view showing an appearance of an tubing pump according to the present invention; 
           [0023]      FIG. 2  is a perspective view showing a state where a front door of the tubing pump according to the present invention is opened; 
           [0024]      FIG. 3  is an exploded perspective view showing a structure of the tubing pump according to the present invention; 
           [0025]      FIGS. 4A to 4C  are diagrams showing a positional relationship between a pump cam and a pump block in the tubing pump according to the present invention; 
           [0026]      FIG. 5  is a diagram showing a cam profile of the pump cam in the tubing pump according to the present invention; 
           [0027]      FIGS. 6A to 6D  are schematic diagrams showing a deformation and restoration state of a tube in the tubing pump according to the present invention; 
           [0028]      FIGS. 7A and 7B  are diagrams showing a positional relationship between a valve cam and a valve in the tubing pump according to the present invention; and 
           [0029]      FIG. 8  is a timing chart showing operational timings of the pump block and the valve in the tubing pump according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the embodiment corresponds to the drawings of  FIGS. 1 to 8 . In the following description, reference numerals are used to describe elements when there is any appropriate drawing to reference to. 
       Embodiment 
       [0031]      FIGS. 1 and 2  show an appearance of an tubing pump  1  to which a pump mechanism according to the present invention is applied, wherein the tubing pump  1  is an apparatus that forces a fluid (for example, a medicinal fluid or a nutritional agent) in a tube to flow through the pump in a controlled way so as to infuse into a patient&#39;s body. The tubing pump  1  includes a door  20  that opens and closes at the front portion of a pump body  10 .  FIG. 1  shows a closed state of the door  20 , and  FIG. 2  shows an opened state of the door  20 . 
         [0032]    The pump body  10  is shaped approximately like a rectangular box shape. The pump body  10  has a horizontal base  11  that has a door in front that can be opened and closed .an tube  30  that is clamped by a clamping device  40  that is laterally inserted into base  11  (see  FIG. 2 ). The clamped state of the tube  30  by the clamping device  40  is released when the door  20  is closed. 
         [0033]    The horizontal base  11  is the shape of a deep tray and it accommodates the pump mechanism  50  that forcibly transfers the fluid in the loaded tube  30 . The pump mechanism  50  forcibly transfers the fluid in the tube  30  from the upstream side to the downstream side, i.e., in the direction d, by sequentially combining a pressing and opening operational to the loaded tube  30 , an opening-closing operational of a valve  51  on the upstream side thereof, an opening-closing operational of a valve  52  on the downstream side thereof, and the like (see  FIG. 2 ). 
       &lt;Configuration of Pump Mechanism&gt; 
       [0034]      FIG. 3  is an exploded perspective view showing components of the pump mechanism  50 . The pump mechanism  50  includes the upstream side valve  51 , an upstream side valve cam  51  C, the downstream side valve  52 , a downstream side valve cam  52 C, a pump block  53 , a pump block cam  53 C, a guide shaft  53 S, a shaft  54 , a pump block case  55 , and the like. 
         [0035]    Among these components, the tube pressing mechanism unit is formed by the pump block  53 , the pump block cam  53 C, and the guide shaft  53 S as main components. 
         [0036]    The upstream side valve mechanism unit is formed in the pump mechanism  50  by including the upstream side valve  51  and the upstream side valve cam  51  C as main components. A downstream side valve mechanism unit is formed in the pump mechanism  50  by including the downstream side valve  52  and the downstream side valve cam  52 C as main components. 
         [0037]    The upstream side valve cam  51  C, the downstream side valve cam  52 C, and the pump block cam  53 C are fixed to the shaft  54 . The shaft  54  continuously rotates by using an electric motor (not shown) as a power source. 
         [0038]    When the shaft  54  continuously rotates, the upstream side valve cam  51 C, the downstream side valve cam  52 C, and the pump block cam  53 C respectively cause the upstream side valve  51 , the downstream side valve  52 , and the pump block  53  to reciprocate in ranges that are predetermined by the respective cam profiles. 
         [0039]    At the same time, the tube squeezing mechanism unit function in association with the upstream and downstream side valve mechanism units so as to repeatedly squeeze the infusion tube  30  at an appropriate timing, and also to occlude the infusion tube  30  or open the infusion tube  30  on the upstream side and the downstream side. Hence, the fluid in the infusion tube  30  is transferred. 
       &lt;Tube Squeezing Mechanism Unit&gt; 
       [0040]    As described above, the tube pressing mechanism unit includes the pump block  53 , the pump block cam  53 C, and the guide shaft  53 S. 
         [0041]    The position of the pump block  53  that vertically reciprocates is determined by the position of the pump block cam  53 C that is fixed to the rotating shaft  54  which causes the cam to rotate. 
         [0042]      FIGS. 4A to 4C  show the cam profile of the pump block cam  53 C. The position of the pump block  53  is determined by the position at which the cam surface of the pump block cam  53 C having the cam profile shown in  FIGS. 4A and 4C  contacts with the upper bearing unit  53   u  or the lower bearing unit  53   d  of the pump block  53  when the pump block  53  moves vertically from the immediate position where the pump block  53  is located. 
         [0043]      FIG. 4A  shows a positional relationship between the pump block  53  and the pump block cam  53 C in a situation where the pump block  53  is located at the uppermost position. 
         [0044]      FIG. 4B  shows a positional relationship between the pump block  53  and the pump block cam  53 C in a situation where the pump block  53  is located at the intermediate position. 
         [0045]      FIG. 4C  shows a positional relationship between the pump block  53  and the pump block cam  53 C in a situation where the pump block  53  is located at the lowermost position. 
         [0046]    In addition, the pump block  53  is guided and move vertically using guide shafts  53 S that pass through the ball bushing units  53   b  located on the upstream side and the downstream side. 
         [0047]    The pump block  53  is held by the guide shaft  53 S, and thus the pump block  53  may be restricted from moving in other directions when the pump block  53  vertically reciprocates. 
         [0048]    In addition, the pump block  53  is restricted from moving in other directions, thereby allowing vibration and noise generated during the operational of the tubing pump  1  to be controlled and contributing to the flow rate accuracy of the infusion pump. 
         [0049]    A V-groove  53   v , which is a concave area having an approximately V shape, is formed in the pump block  53 , and the infusion tube  30  is loaded along the V-groove  53   v.    
         [0050]    The pump block&#39;s front facing component  21  is fixed to the door  20  at a position opposite to the pump block  53  when the door  20  is closed. 
         [0051]    The tube  30  is loaded in a diamond-shaped space formed by the V-groove  21   v  which has a concave area with an approximate V shape on the pump block&#39;s front facing component  21  and the V-groove  53   v  of the pump block  53  that is opposite to each other (see  FIGS. 6A and 6C ). 
         [0052]    From this setup, when the pump block  53  vertically reciprocates, the tube  30  is repeatedly pressed (see  FIGS. 6B and 6D ). 
         [0053]    When the diamond-shaped space is formed again upon released from a state ( FIG. 6B ) where the tube  30  is squeezed during the operational of the pump block  53 , the shape of the tube  30  tries to return to its state prior to being squeezed by the elastic force of the tube  30  material and also by the pressure of the fluid flowing into the tube  30 . 
         [0054]    At the same time, the tube  30  is pressed from both sides by the inclined surface of the V-groove  53   v  and the inclined surface of the V-groove  21   v  in addition to the tube  30  material&#39;s elastic force and the pressure of the fluid. Thus, the shape of tube  30  will be restored. 
         [0055]    For this reason, the shape of the tube  30  can be reliably restored every time when tube  30  is pressed. Hence, the transfer amount of the fluid is stable every time the tube  30  is pressed and restored, thereby improving the flow rate accuracy. 
       &lt;Valve Mechanism Unit&gt; 
       [0056]    The valve mechanism unit includes the upstream side valve  51  and the upstream side valve cam  51  C on the upstream side, and includes the downstream side valve  52  and the downstream side valve cam  52 C on the downstream side. 
         [0057]    The function of the valve  51  ( 52 ) that occludes the tube  30  and the release of the occlusion of the infusion tube  30  is determined by the profile of the valve cam  51  C ( 52 C) that rotates around the rotating shaft  54 . 
         [0058]      FIG. 7A  shows the positional relationship between the valve  51  ( 52 ) and the valve cam  51  C ( 52 C) when the valve  51  ( 52 ) is in a state where the valve  51  ( 52 ) opens tube  30 . 
         [0059]      FIG. 7B  shows the positional relationship between the valve  51  ( 52 ) and the valve cam  51 C ( 52 C) when the valve  51  ( 52 ) is in a state when the valve  51  ( 52 ) occludes tube  30 . 
         [0060]    Since the upstream side valve  51  and the downstream side valve  52  are separate components, an ideal valve angle may be set by largely forming a movable unit, and thus the flow rate accuracy is improved as the infusion pump is improved. 
         [0000]    &lt;Operational Relationship between Pump Block and Valve&gt; 
         [0061]      FIG. 8  is a timing chart showing the operational timings of the pump block  53 , the upstream side valve  51 , and the downstream side valve  52  when the shaft  54  rotates one revolution in the tubing pump  1  of the present embodiment. 
         [0062]    When the shaft  54  rotates one revolution, the pump block  53  vertically reciprocates once. 
         [0063]    When the shaft  54  rotates one revolution, the upstream side valve  51  performs an operational of opening and closing the valve twice. 
         [0064]    At the same time, the downstream side valve  52  performs the operational for opening and closing the valve twice at timings when the upstream side valve  51  and downstream side valve  52  alternate with each other.  FIG. 8  shows the operational relationship between them. 
         [0065]    The horizontal axis of  FIG. 8  represents the angles at which three different rotating component, that is, the pump block cam  53 C, the upstream side valve cam  51  C, and the downstream side valve cam  52 C, rotate with the shaft  54 . 
         [0066]    The vertical axis of  FIG. 8  represents the displacement of the pump block  53 , the upstream side valve  51 , and the downstream side valve  52 . 
         [0067]    As shown in  FIG. 8 , in the present embodiment, for the valves  51  and  52 , the difference between occluded and open is set to a value of 1. For the pump block, each pump cycle from the intermediate or zero position is set to 3. 
         [0068]    When the fluid in the infusion tube  30  is sucked (filled), the pump block cam  53 C brings the pump block  53  into operational at the range of 44° indicated as “F” in  FIG. 5 . At this range, the upstream side valve  51  opens the infusion tube  30 , and the downstream side valve  52  occludes the infusion tube  30 . As the pump block  53  further moves toward the intermediate position, the fluid is sucked (filled). 
         [0069]    When the fluid in the tube  30  is discharged (pumped), the pump block cam  53 C brings the pump block  53  into operational at the range of 70° indicated as “P” in  FIG. 5 . At range, the upstream side valve  51  occludes the infusion tube  30 , and the downstream side valve  52  release the occlusion on the infusion tube  30 . The fluid is discharged by the inclined surface of the V-groove  53   v  of the pump block  53  to press the infusion tube  30 . 
         [0070]    One of the elements for increasing the flow rate accuracy of the infusion pump is to increase the proportion of discharging time as much as possible after considering various conditions such as the opening and closing timings of the valve or elastic force of the tube. 
         [0071]    It is necessary to set a wide cam angle range of the pump block cam  53 C for discharging (pumping). In the related art in which the pumping operational is performed using a driving component for pressing the tube, operating the cam at upstream side valve and operating the cam at the downstream side valve, it is not likely that the cam angle range of the pump block cam  53 C can be set larger than 60°. 
         [0072]    However, in the present embodiment, different cams are used to change the operational angles of the pump block  53 , the upstream side valve  51 , and the downstream side valve  52 , thus, a wider range can be designed. As a result, the cam angle range may be set to at least 70°. 
         [0073]    In addition, according to the above-described embodiment, the cam angle range for discharging (pumping) is set to 70°, and the cam angle range for sucking (filling) is set to 44°. However, different angle ranges can be set to predetermine the opening and closing timings of the upstream and downstream side valves. 
         [0074]    Further, according to the above-described embodiment, one shaft  54  is used as a common rotating shaft for the pump block cam  53 C, the upstream side valve cam  51  C, and the downstream side valve cam  52 C. However, individual rotating shafts can be use on all or some of them. 
         [0075]    According to the present invention, a tubing pump capable of further improving flow rate accuracy can be configured. 
         [0076]    While this invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.