Patent Publication Number: US-2021170163-A1

Title: Peristaltic pump

Description:
TECHNICAL FIELD 
     The invention relates to the field of peristaltic pumps for various applications. One application field is the medical field. The peristaltic pump according to the invention comprises some unique features in particular an opening and closing mechanism that is accentuated by a pivotable cover, which pivotable cover is connected to a tube pressuring portion via elastic elements. The elastic elements are thereby connected via at least one adjustable element so that the tension or pre-tension in the elastic element can be adjusted to tube types and material, to the viscosity of the pumped fluid and to the amount of fluid that needs to be pumped. 
     BACKGROUND OF THE INVENTION 
     In the medical field peristaltic pumps are used quite often, since this technology allows to avoid contact between the fluid (gas or liquid) to be pumped and the actual pump via a tube. Peristaltic pumps for medical applications are usually integrated in units that comprise other devices, for instance in intensive care units. The peristaltic pumps are typically used for a comparably long time and since they help to keep up vital functions a failure of a peristaltic pump is not an option. Peristaltic pumps used in medical applications have to be reliable and durable. 
     Many prior art pumps comprise mechanism that press a tube comprising a fluid to be pumped towards a rotor having rollers or the like so that the rollers can push the fluid in the tube. Such mechanism further comprise holders or clamps that squeeze the tube on inlet- and outlet side of the pump so that the rotor, which is arranged in between the holder on the inlet side and the holder on the outlet side, cannot move the tube when rotating and thus pumping the fluid. The clamping or holding on the inlet side is thereby more important than the clamping or holding on the outlet side, since the rotor is urging the tube to glide in the direction of pumping and the rotor will thus draw the tube away from the inlet side of the peristaltic pump in the direction of pumping. The outlet side holder merely has the task of holding the tube in position. In known pumps such mechanisms are normally not adjustable by the operator or medical personnel. They only provide a factory set tension or pressure force for pressuring the tube towards the rotor and for holding the tube in position on the inlet- and outlet side of the pump respectively. This can pose problems if the viscosity of the fluid changes or if the stiffness of the tube varies, thus if another tube material, size or strength (wall thickness) of the tube is used or if different fluid volumes need to be pumped. 
     As medicine, oxygen, blood or other fluids can be pumped with peristaltic pumps, these pumps further have to be very precise. Therefore the construction of such peristaltic pumps has to be exact and it shall be performed with minimal tolerances. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a peristaltic pump that is flexible in its use and reliable. 
     Another object is to provide a peristaltic pump that is durable and can be used for various applications. 
     A further object is to provide a peristaltic pump that is easy to use and precise. 
     The inventor(s) of the present invention have realized that it is possible to provide a peristaltic pump for medical applications comprising an opening and closing mechanism that is coupled to a pivotable cover, said opening and closing mechanism being adjustable in various ways so that the contact pressure of the tube towards a rotor of the peristaltic pump can be adjusted and that a clamping force of the tube, at least on a pump inlet side, can be adjusted. The opening and closing mechanism is coupled to the pivotable cover so that it is engaged and disengaged when the pivotable cover is closed and opened, respectively. The inventor(s) further realized that if the opening and closing mechanism is provided with high precision, the adjustability and accuracy further improves. 
     Disclosed herein is a peristaltic pump for medical applications comprising a motor, a rotor coupled to the motor, a housing in which the rotor is arranged, an opening and closing mechanism comprising a tube pressuring portion, a slider and a pivotable cover coupled to the housing and the slider. The opening and closing mechanism further comprises an elastic element connected to the slider and the tube pressuring portion so that a tube engaging surface of the tube pressuring portion slides towards and away from the rotor upon closing and opening of the pivotable cover, respectively. The housing comprises a first adjustable motion link, the tube pressuring portion comprises a frame that extends into the housing said frame comprising at least two guiding elements and in that the tube pressuring portion&#39;s movement towards and away from the rotor is guided by the at least two guiding elements, which interact with the first adjustable motion link. The tube pressuring portion comprises an adjustment element to which the elastic element is connected so that the tension in the elastic element can be adjusted. The opening and closing mechanism further comprises a post attached to the slider, the pivotable cover comprising a rotating shaft having an extension extending perpendicular to a longitudinal direction defined by the rotating shaft. The extension being configured to engage the post for moving the slider and via the elastic element also the tube pressuring portion away and towards a top of the housing, when the pivotable cover is opened and closed, respectively. 
     The above peristaltic pump provides an adjustable opening and closing mechanism, in which the pressure or force at which the tube pressuring portion is pressed towards the rotor can be varied and adjusted. 
     The post may be chamfered at its free end. Such a chamfered free end may provide an initial resistance to the actual opening movement of the pivotable cover. As soon as the extension or the free end of the extension is moved below the chamfered free end then the force needed to open the pivotable cover decreases. The chamfered free end of the post provides for a self-locking of the pivotable cover when the cover is closed and for example under adjustment. Thus even when the elastic elements are highly pre-tensioned the pivotable cover will not open due to the self-locking effect of the chamfered post. In other words, the higher the force of the pre-tensioning the more the pivotable cover wants to stay in its position. 
     The above explained chamfered free end of the post may be beneficial if the extension comprises a roller at its free end. 
     The guiding elements may be rollers, sleeve bearings, gliding surfaces or any other suitable element that can engage the first adjustable motion link. In a similar way the first and second motion links may be cam surfaces, surfaces or any other suitable motion guiding means. 
     The, preferably single, adjustment element is configured to adjust the pump to various system pressures. This allows to make sure that the pump is always running in its optimal range depending on the system pressure. 
     In an embodiment the peristaltic pump comprises a second motion link and the first adjustable motion link may be adjustable by at least one screw and the frame may comprise four guiding elements whereby two of them engage the first motion link and two of them engage the second motion link. 
     The effect of the above is that the tube pressuring portion comprising the frame is guided via the first and second motion link in a kinematically overdetermined way. Thus the frame and therewith the tube pressuring portion cannot move sideways with respect to the longitudinal direction of the first and second motion link and the movement of the frame and the tube pressuring portion is very precisely and smoothly guided. 
     In an embodiment the peristaltic pump may comprise a bridge connecting the adjustment element to the elastic element, wherein the frame comprises a cut-out having a bottom wall and two side walls and one stop protrusion extending from each of the two side walls. The bridge being arranged movable in the cut-out between the bottom wall and the stop protrusions. 
     The bottom wall is arranged at an end of the frame closest to the bottom of the peristaltic pump. The bottom wall may further comprise a through passage or the like so the adjustment element can engage the bridge. The stop protrusion prevents the bridge from being drawn too far away from the bottom wall by the elastic element in case the adjustment element is disengaged from the bridge by mistake. 
     In one embodiment a pair of elastic elements symmetrically parallel-connected to the adjustment element via the bridge are provided. 
     Two elastic elements symmetrically connected to the bridge provide for a symmetric force or tension on the bridge and thus on the tube pressuring portion. 
     In another embodiment the housing may comprise a front portion and a back portion and whereby the rotor is arranged in the front portion and the slider, the elastic element (s), the frame, the adjustment element and the first and second motion links are arranged in the back portion. 
     Such a separation may protect the mechanical pieces of the opening and closing mechanism in the back portion from dust and abrasion from the tube. 
     In another embodiment the slider may comprise a pin extending in the same direction from the slider as the post, said pin being arranged in line with the post as seen in a direction perpendicular to the longitudinal direction defined by the rotating shaft. The extension may comprise a roller that engages the post upon closing of the pivotable cover for moving the slider towards the top of the housing and the roller may engage the pin upon opening of the pivotable cover for moving the slider away from the top of the housing. 
     The above explained pin and post combination arranged and fixed to the slider provides for a very smooth transition and movement of the opening and closing mechanism when the pivotable cover is opened and closed, respectively. 
     In another embodiment the peristaltic pump may comprise an adjustable adapter, whereby the elastic element(s) are connected to the slider via the adjustable adapter. The adjustable adapter may comprise a threaded shaft having a hole and a nut for fastening the latter to the slider. 
     This allows to change the range of pre-tension that is possible to provide with the elastic element(s) depending on application field and circumstances, such as temperature, size of tube, material of tube etc. 
     In a further embodiment the housing may comprise a pump inlet side and a pump outlet side each of the pump inlet side and the pump outlet side comprising a tube receiving opening. The opening and closing mechanism may further comprise an inlet tube holder portion and an outlet tube holder portion each of the inlet tube holder portion and the outlet tube holder portion being arranged next to the corresponding pump inlet side and pump outlet side, respectively. Each of the inlet tube holder portion and the outlet tube holder portion may be coupled to the slider via a corresponding elastic element and they may be configured to increase and decrease the size of the corresponding tube receiving opening upon opening and closing of the pivotable cover. 
     The increasing and decreasing of the size of the corresponding tube receiving opening leads to a clamping and thus a temporary fixation of the tube when the pivotable cover is closed and to a release of the tube when the pivotable cover is opened. 
     In a further embodiment the elastic element connecting the inlet tube holder portion to the slider may be connected to the inlet tube holder portion via a positioning element in order to adjust position of the inlet tube holder portion. 
     This allows to set the position of the inlet tube holder portion and, if wanted, to already provide a slight pre-tension in the elastic element. The above feature provides for a simple adjustment of the position of the inlet tube holder portion to various tube sizes for example. 
     In a further embodiment the tube pressuring portion may comprise a stop element that is configured to engage the adjustment element so that the adjustment element cannot move any longer once the tension of the elastic element(s) is set. 
     This may increase the reliability of the peristaltic pump and increase long-term stability of the chosen tension in the elastic element(s) used to press the tube pressuring portion towards the rotor when the pivotable cover is closed. 
     In another embodiment the inlet tube holder portion may comprise a pre-tension device configured to be screwed onto the adjustment element in order to provide a pre-tension in the elastic element. 
     Thus the force with which the inlet tube holder portion clamps the tube when the pivotable cover is closed may be directly adjustable. In many or almost all cases at least a small engagement of the elastic element is wanted when the tube is positioned and clamped by the inlet tube holder portion. Such an adjustment may be beneficial in order to adapt the force at which the tube is clamped to tube size, the material stiffness of the tube, in some lengths also the viscosity of the fluid and the fluid pressure in the system. 
     In a further embodiment the inlet tube holder portion may comprise a stop element configured to engage the positioning element in order to lock the positioning element after a tension in the elastic element has been set. 
     The above may increase reliability and long term stability of the force or clamping force applied on the pump inlet side to the tube, when the tube is engaged in the pump. 
     The elastic elements may be springs and the adjustment elements may be screws. 
     The effect of using screws is that the pre-tension in the elastic elements can be steplessly adjusted. 
     The elastic elements or springs may even be configured to be exchangeable or interchangeable so that springs or elastic elements with various spring constants can be used and installed in the peristaltic pump. 
     The guiding elements are rollers and they may have a U- or V-shaped profile or any combination thereof and the first and second motion links may be bars that fit into said U- or V-shaped profile of said rollers. 
     The U- or V-shaped profile and the fitting of the first and second motion link respectively into said U- or V-shaped profile provides for a determined and gap-free movement. Further due to the U- or V-shaped profile (or combination thereof) the movement of the tube pressuring portion is locked in a z-direction (height) of the peristaltic pump and the noise level during movement is reduced while at the same time the accuracy is very high. 
     In another embodiment the rotating shaft may comprise a sensor element and the housing may comprise a corresponding sensor, the sensor element and sensor may be arranged so that it can be detected, whether the pivotable cover is open or closed. 
     The sensor and sensor element may be used to detect whether or not it is safe to switch on the peristaltic pump and/or to simply detect whether or not the pivotable cover is closed or open. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, for exemplary purposes, in more detail by way of an embodiment(s) and with reference to the enclosed drawings, in which: 
         FIG. 1  schematically illustrates an exploded, perspective view of the peristaltic pump according to the invention; 
         FIG. 2  schematically illustrates another exploded, perspective view of the peristaltic pump according to the invention; 
         FIG. 3  schematically illustrates a perspective view of the peristaltic pump according to the invention with a pivotable cover in a closed position; 
         FIG. 4  schematically illustrates the peristaltic pump according to the invention with certain parts of the housing removed for illustrative purposes; 
         FIG. 5 a    schematically illustrates a perspective view of a part of the peristaltic pump according to the invention and of an opening and closing mechanism of the peristaltic pump according to the invention; 
         FIG. 5 b    schematically illustrates a top down view onto the part of the peristaltic pump shown in  FIG. 5   a;    
         FIG. 6  schematically illustrates a bottom up view of the peristaltic pump according to the invention; 
         FIG. 7  illustrates a cross sectional view of the peristaltic pump according to the invention, the cross section being taken along line VII-VII of  FIG. 6 ; 
         FIG. 8  illustrates a cross sectional view of the peristaltic pump according to the invention, the cross section being taken along line VIII-VIII of  FIG. 6 ; 
         FIG. 9  schematically illustrates a perspective view of another embodiment of the peristaltic pump according to the invention, with a housing removed; 
         FIG. 10  illustrates a view onto a cross section of the embodiment according to  FIG. 9  cut along plane X-X; and 
         FIG. 11  illustrates a top down view onto the embodiment of  FIG. 9  with the pivotable cover closed and the housing removed. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  illustrate exploded and perspective views of a peristaltic pump  1  according to the invention. The peristaltic pump  1  comprises a motor  2 , a rotor  4  and a housing  6 . The motor  2  comprises a drive axis  10  that extends partially through the housing and that is connected to the rotor  4 . The rotor  4  comprises drive elements  12 , in the form of rollers that are configured to engage a tube (not shown) comprising a fluid to be pumped. The drive elements  12  of the rotor are arranged symmetrically along the circumference of the rotor  4 . In the embodiment shown the rotor  4  comprises four drive elements  12  covering a 90° degree angle. It is however clear that any number of drive elements  12  from three (covering a 120° degree angle) upwards can be installed in the rotor. 
     The housing  6  comprises a base plate  14 , a back portion  16  and front portion  18 . The motor  2  is connected to the base plate  14  via screws and the back portion  16  and the front portion  18  are connected to the base plate  14  via screws. The housing  6  further comprises a top  13  and a bottom  15 . 
     The back portion  16  comprises a separating wall  34  for separating mechanical parts from dust and tube residuals, an outlet side guide track  40  and an inlet side guide track  42 . These guide tracks  40 ,  42  are configured to let a tube engaging protrusion  80 ,  92  of a tube inlet holder portion  30  and tube outlet holder portion  32 , respectively, pass. The separating wall  34  comprises various through holes for the screws that hold the base plate  14 , the back portion  16  and the front portion  18  together and for the drive axis  10  to pass through and reach the rotor  4 . The through holes may further comprise O-rings in order to hermetically separate the front portion  18  from the back portion  16  of the peristaltic pump  1 . 
     The front portion  18  comprises a pump inlet side  44  and a pump outlet side  46 . The tube (not shown) that comprises the fluid (gas or liquid) to be pumped runs into the peristaltic pump  1  via the pump inlet side  44  and a tube receiving opening  98 , respectively, into the area of the rotor  4 , where it is held in position via a tube pressurizing portion  28  and out of the peristaltic pump  1  through the pump outlet side  46  and a further tube receiving opening  100 , respectively. 
     The front portion  18  further comprises a window  48  made of an at least partially see-through material that allows to see from the outside of the peristaltic pump  1 , if the rotor  4  is running even when a pivotable cover  22  is closed, as illustrated in  FIGS. 1 and 2 . 
     The pivotable cover  22  is part of an opening and closing mechanism  8 , which will now be at least partially explained referring to  FIGS. 1 and 2 . The opening and closing mechanism  8  comprises a slider  20 , which is embedded in the back portion  16  of the housing  6 , the pivotable cover  22 , two elastic elements  24  in the form of springs (can also be rubber elements or the like) and the tube pressuring portion  28 . The two elastic elements  24  are coupled, via one of their ends to the slider  20  via screws comprising a receiving opening for a hook of the elastic elements  24 . The elastic elements  24  are also connected to the tube pressuring portion  28 . Details of this connection will be explained referring to  FIGS. 5 a    and  5   b.    
     The pivotable cover  22  comprises a front cover  58 , which is made of an at least partially transparent material, which allows to see a tube, when it is arranged in the peristaltic pump  1 . The front cover  58  is connected to a rotating shaft  60  that extends through the front portion  16 , via arms  56  on the inlet side  44  and the outlet side  46 , respectively. 
     The slider  20  comprises recesses  50 , a post  52 , which is chamfered at its free end and a pin  54 . The slider  20  is arranged movable in the back portion  16  and the post  52  and the pin  54  are configured to extend through a longitudinal opening  41  in the separating wall  34  into the front portion  18 . The post  52  and the pin  54  are configured to be engaged by the rotating shaft  60  of the pivotable cover  22  upon opening and closing of the pivotable cover. 
       FIG. 3  illustrates a perspective view of the peristaltic pump  1  assembled and ready to be used or built into a medical unit. The housing  6  is illustrated comprising the base plate  14 , the back portion  16  and the front portion  18 . Further also the motor  2  is visible. The pivotable cover  22  is illustrated in the closed position. The arrow i) illustrates where a tube comprising a fluid to be pumped would enter the peristaltic pump  1 . 
     The functioning of the opening and closing mechanism  8  will now be explained in detail referring to  FIGS. 4 to 8 . 
       FIG. 4  illustrates the peristaltic pump  1  with the pivotable cover  22  in its open position. The front portion  18  (not shown in  FIG. 4 ) is removed for illustrative purposes and only the back portion  16  and the base plate  14  of the housing  6  are shown. The pivotable cover  22  is in the open position and the tube pressurizing portion  28  is therewith in a position moved away from the rotor  4  so that a tube (not shown) can be placed in between a tube engaging surface  63  of the tube pressuring portion  28  and the rotor  4  and its drive elements  12 , respectively. The rotating shaft  60  of the pivotable cover  22  comprises a first extension  102  or protrusion comprising a roller  122 , which roller  122  engages the post  52  with the chamfered free end upon moving of the pivotable cover  22  into a closed position. The extension  102  extends in a direction more or less perpendicular to a longitudinal direction of the rotating shaft  60 . By closing the pivotable cover  22  the extension  102  and the roller  122  will push the post  52  and therewith the slider  20  towards the top  13  of the housing  6  and the back portion  16 , respectively. The post  52  extends through the longitudinal opening  41  in the separating wall of the back portion  16 . 
     Still referring to  FIG. 4 , the rotating shaft  60  comprises a second extension  99  comprising a sensor element (not visible in  FIG. 4 ) at its free end, which sensor element is configured to interact with a sensor  43  on the separating wall  34  of the back portion  16  of the housing  6 . As can be seen in  FIG. 4 , the second extension  99  is also extending more or less in a direction perpendicular to the longitudinal direction of the rotating shaft  60  but about or approximately 90° offset the first extension  122 . The sensor element  101  will be in comparably close contact or even in physical contact with the sensor  41  when the pivotable cover  22  is in a closed position. Thus sensor  41  is able to detect whether or not the pivotable cover  22  is in its closed position. 
     The sensor  41  may be a magnetic sensor such as a hall type sensor or an electromechanical sensor. 
     In  FIG. 4 , there are further the inlet tube holder portion  30  and the outlet tube holder portion  32  illustrated. Since the inlet- and outlet tube holder portions  30 ,  32  are also coupled, via elastic elements (not visible in  FIG. 4 ) to the slider  20 , they are also shown in a position moved away from the top  13  of the peristaltic pump  1 . More specifically the inlet- and outlet tube holder portions  30 ,  32  are configured to change the size of the tube receiving opening  98 ,  100  in the front portion (c.f.  FIGS. 1 and 2 ) and the pump inlet side  44  and the pump outlet side  46 , respectively. Thus upon closing of the pivotable cover  22 , the inlet- and outlet tube holder portions  30 ,  32  are configured to move upwards towards the top  13  of the peristaltic pump  1  in order to decrease the size of the corresponding tube receiving opening  98 ,  100  in order to clamp the tube (not shown) via a corresponding tube engaging protrusion  80 ,  92  having a V-shape  112 ,  116  and to increase the size of the corresponding tube receiving opening  98 ,  100  in order to release the tube (not shown) upon opening of the pivotable cover  22 . The V-shape  112 ,  116  of the tube engaging protrusions  80 ,  92  may alternatively be U-shaped or any other shape that is able to engage a tube. 
     Although the outlet and inlet side are illustrated in the figures, it is clear that they can be interchanged, since the peristaltic pump is configured to fluid in both directions, which can be easily achieved by changing the direction of rotation of the rotor. 
     Referring to  FIGS. 5 a  and 5 b    the functioning of the opening and closing mechanism  8  of the peristaltic pump  1  is now explained.  FIGS. 5 a  and 5 b   , whereby  FIG. 5 a    is a perspective view and  FIG. 5 b    is a top down view of the same part of the peristaltic pump  1 , illustrate the peristaltic pump  1  with the motor  2  and base plate  14  removed in order to make various parts of the opening and closing mechanism visible. 
       FIGS. 5 a  and 5 b    illustrate very well how the slider  20  is connected to the tube pressuring portion  28  via the elastic elements  24  and a bridge  26 . The bridge  26  is connected to the tube pressuring portion  28  via an adjustment element  64  that is engaged in the tube pressuring portion  28  and a frame  70  of the tube pressuring portion  28 , respectively, and the bridge  26 . The elastic elements  24  are connected to the slider  20  via screws that for example comprise a hook, which can engage in a hook of the corresponding elastic element  24 . The bridge  26  may comprise connecting protrusions  62  ( FIG. 5 a   ) comprising two holes for engaging hooks of the corresponding elastic elements  24 . Thus the elastic elements  24  can be exchanged so that the elastic elements  24  or springs with different spring constants can be installed in the peristaltic pump  1 . The connecting protrusions  62  are optional and not needed in order to achieve the function of the opening and closing mechanism  8 . 
     The adjustment element  64  is shown as a single adjustment element  64 . This is advantages since only one adjustment element  64  is used to change the pre-tension this is smooth and saves time. The adjustment element  64  allows to adjust the peristaltic pump to various system pressures so that it will function optimally. The frame  70  of the tube pressurizing portion  28  comprises four symmetrically arranged guiding elements  104  in the form of rollers. The frame  70  is fixedly connected to the tube pressuring portion  28  and forms part of it, the connection may be achieved via screw and thread combination. The frame  70  has a rectangular shape as seen in a top down view ( FIG. 5 b   ) the rectangular shape defining a cut-out  105  having a side walls  109 , a bottom wall  107  and a top wall  111 . For illustrative purposes the bottom wall  107 , the stop wall  111  and the side walls  109  are only referenced in  FIG. 5 a   . The side walls  109  comprise each a stop protrusion  106 . The stop protrusions  106  have the function of stopping the movement of the bridge  26  towards the slider  20  when the adjustment element  64  in the form of a screw is rotated in order to adjust the pre-tension in the elastic elements  24 . The bridge  26  can thus not move all the way to the top wall  111  and it is always possible to engage the adjustment element  64  again in the bridge  26 , even when the adjustment element  64  is by mistake disengaged and the elastic elements  24  is drawn towards the slider  20  by the elastic elements  24 . The adjustment element  64  may be engaged in the bottom wall  107  of the frame  70  and a bottom of the tube pressurizing portion  28  or in one of the two elements. In the illustrated embodiment the adjustment element  64  is embedded in the bottom wall of the tube pressurizing portion  28  and the bottom wall  107 . As mentioned previously the elastic elements  24  are embodied in the form of springs. The top wall  111  comprises openings  108  ( FIG. 5 a   ) in order to let the elastic elements  24  pass through. 
     The guiding elements  104  are provided in the form of rollers connected to the side walls  107  of the frame  70 , for example via screw-bearing combination. Although the four guiding elements  104  are illustrated in the embodiment shown, it is actually possible to provide only two or more than four guiding elements  104 . The advantage with four guiding elements  104  is that the movement of the frame  70  and therewith the tube pressuring portion  28  is kinematically overdetermined and gap-free. Due to the first adjustable motion link  36  the system can be deformed until all four guiding elements  104  engage the first and second motion link  36 ,  39 , respectively, which provides for a good angle stiffness of the movement. Referring now to  FIG. 5 b    in can be seen that half of the guide elements  104  on one side wall  109  engage a first adjustable motion link  36  and the other half of the guide elements  104  on the other side wall  109  engage a second motion link  39 . The first adjustable motion link  36  and the second motion link  39  form part of the back portion  16  of the housing  6  and are connected to the back portion  16  via screws. The first adjustable motion link  36  is adjustable via two screws  96  that are screwed into a protrusion of the back portion  16 , whereby said protrusion extends towards the top  13  of the peristaltic pump  1 . A similar protrusion may be provided to connect the second motion link  39  to the back portion  16 . The adjustability of the first adjustable motion link  36  is provided in order to make sure that the first adjustable motion link  36  and the second motion link  39  are as parallel as possible so that during movement as little friction as possible exists and that other forms of movement problems that can occur due to lacking accuracy can be avoided and minimized in order to provide a very smooth and precise movement. During the opening and closing of the pivotable cover  22  the tube pressurizing portion  28  and the slider  20  move in a direction indicated by arrow ii) in  FIG. 5 b   . The first adjustable motion link  36  is thus adjustable in a direction at least more or less perpendicular to the direction indicated by the arrow ii). 
     In an embodiment that is not shown in the figures, only one adjustable motion link may be provided. The adjustable motion link may be engaged by the two guiding elements, one on each side, or, if more than two guiding elements, for instance four guiding elements are provided, by two guiding elements on each side. 
       FIG. 5 b    further illustrates that the elastic elements  24  are connected to the slider  20  by adjustable adapters  55  configured to hold the elastic elements  24 . The adapters may be screwed into the slider  20  or connected to it via a thread-shaft and nut combination while the thread shaft comprises a hole in order to hold an end of each of the elastic elements  24 . The adjustable adapters  55  allow to move the range of pre-tension, for example in Newton, of the opening and closing mechanism  8  and the force with which the tube pressurizing portion is pressed towards the rotor  4 , respectively. This further increases application fields of the peristaltic pump  1  and it also provides a high flexibility. 
     In the in  FIGS. 5 a  and 5 b    illustrated closed position of the pivotable cover  22  the frame  70  and the tube pressuring portion  28  are moved upwards towards the top  13  of the housing  6  and the back portion  16 , respectively. Thus when the pivotable cover  22  is opened, the frame  70  and the tube pressuring portion  28  will move downwards away from the top  13  of the housing  6  and the separating wall  34  of the back portion  16 , respectively, so that a tube can be positioned between the tube pressurizing portion  28  and the rotor  4  (not shown in  FIGS. 5 a  and 5 b   ). In order to further improve the movement of the tube pressurizing portion  28  and the frame  70  there may be gliding surfaces  68  ( FIG. 5 a   ) employed on the back portion  16  and the corresponding surfaces of the tube pressurizing portion  28 . The gliding surfaces  68  may comprises an element polymer or similar material such as for example Teflon or the like. In particular a gliding surface  68  may be arranged between the separating wall  34  of the back portion  16  and the tube pressurizing portion  28  as indicated in  FIG. 5 a   . Such gliding surfaces  68  increases the robustness of the opening and closing mechanism  8 , it reduces friction and further provides a force absorption when the tube pressuring portion  28  is closed. These effects lead to an increased lifetime of the peristaltic pump and to an improved stiffness. 
     Still referring to  FIG. 5 a    the tube receiving opening  100  on the pump outlet side  46  is illustrated. The tube receiving opening  100  has at least a partial V-shape  120  (or U-shape) that is configured to interact, as shown in  FIG. 4 , with the V-shape  116  of the tube engaging protrusion  92  of the outlet tube holder portion  32  in order to decrease and increase the tube receiving opening  100  on the pump outlet side  46  upon closing and opening of the pivotable cover  22 . Similarly does the tube receiving opening  98  comprise a V-shape  112  (or U-shape) as illustrated in  FIG. 1  that interacts with the V-shape  112  of the tube engaging protrusion  80  of the inlet tube holder portion  30  as shown in  FIG. 4 . 
     The functioning of the inlet tube holder portion  30  and the outlet tube holder portion  32  will now be explained referring to  FIGS. 6 and 7 .  FIG. 6  is a bottom up view of the peristaltic pump  1  illustrating various elements previously explained, including the housing  6 , the motor  2  and the base plate  14 , the back portion  16  and the front portion  18  of the housing  6  and the pivotable cover  22 .  FIG. 7  is a cross sectional view of  FIG. 6  through line VII-VII, thus through the inlet tube holder portion  30 . The inlet tube holder portion  30  comprises a positioning element  72  in the form of a screw, which positioning element  72  is embedded in a recess  82  via an elastic element  74 , here shown in the form of a spring. The positioning element  72  extends via a hole in the outlet tube holder portion  30  into the slider  20  so that the outlet tube holder  30  moves together with the slider  20  upon opening and closing of the pivotable cover  22 . The position of the elastic element  74  can be adjusted and by rotating the positioning element/screw  72 . This may be done in order to adjust the position and an initial pressure with which the V-shapes  112 ,  118  of the tube receiving opening  98  ( FIG. 6 ) and the tube engaging portion  80 , respectively, clamp or squeeze a tube when the pivotable cover  22  is in its closed position. In order to lock the position of the positioning element  72  the tube inlet holder portion  30  further comprises a stop element  78 , illustrated in the form of a setscrew that fits and engages a thread in the slider  20 , in which thread also the positioning element  72  is embedded but from an opposite side. The inlet tube holder portion  30  may further comprise a pre-tension device  76  for example in the form of a nut, which pre-tension device  76  is used to further adjust the pre-tension in the elastic element  74  once the position of the tube engaging protrusion  80  is set via the positioning element  72 . The pre-tension element  76  is used to move the position of the tube engaging protrusion  80  in relation to the elastic element  74 . The elastic element  74  is thereby arranged in between the tube engaging protrusion  80  and a head of the positioning element  72  so that a pre-tension can be achieved by changing the position of the pre-tension device  76 . 
     The outlet tube holder portion  32  (illustrated in  FIG. 4 ) may be similarly constructed and engaged in the slider  20  as the inlet tube holder portion  30  via an adjustment element and an elastic element. It may however be connected in a more simple way, for example via an elastic element that replaces the adjustment element and connects the slider to the outlet tube holder portion  32  so that it also moves together with the slider  20 , as explained, upon closing and opening of the pivotable cover  22 . It may be simpler constructed since the holding and temporary fixation of the outlet part of the tube is not that important and mainly fulfils a positioning and holding function, while the clamping and fixation of the tube in the tube receiving opening on the pump inlet side is of more interest since a slippage of the tube on the pump inlet side  44  should be avoided. The tube may however be fixed outside of the peristaltic pump  1  and thus the inlet- and outlet tube holder portion may not be present at all in the peristaltic pump  1 . 
     Turning now to  FIG. 8 , which  FIG. 8  is a cross sectional view of  FIG. 6  through line VIII-VIII, thus through the center of the peristaltic pump  1 .  FIG. 8  further illustrates how the adjustment element  64  of the tube pressurizing portion  28  engages the bridge  26 . Once the pre-tension in the elastic elements  24  is set, the adjustment element  64  can be locked via a stop element  66 , illustrated in the form of a setscrew/screw. 
     The pivotable cover  22  is shown in its closed position and it is well visible, how the post  52  of the slider  20  engages the roller  122  mounted at the first extension  102  of the rotating shaft  60  of the pivotable cover  22 . When the pivotable cover  22  is closed the roller  122  is in contact with the chamfered free end of the post  52  in order to provide an initial resistance to the pivotable cover  22  prior to opening and also to provide a soft “snap” feeling upon closing of the pivotable cover  22 , due the force in the tension elements  24  and the shape of the free end of the post  52 . As can well be seen from  FIG. 8 , the pin  54  is engaged by the roller  122  once the pivotable cover  22  is opened more than a certain, predetermined angle. This angle may be chosen to be in a suitable range. As soon as the pivotable cover  22  is moved above or beyond this angle the roller  122  is starting to engage the pin  54  and pushes the slider  20  away from the top  13  and therewith lets the tube pressurizing portion  28  and the tube inlet holder portion  30  (not shown in  FIG. 8 ) and the tube outlet holder portion  32  (also not shown in  FIG. 8 ) move or glide away from the top  13  of the peristaltic pump  1  and the rotor  4 , respectively. The post  52  may be fixedly connected to the slider  20  via a screw/thread connection. It is to be noted that when the pivotable cover  22  is opened then the slider  20  and the frame  70  and tube pressurizing portion  28 , respectively, do not move together from the beginning of the movement rather only after the pivotable cover  22  is opened beyond said suitable angle. 
       FIG. 8  further also illustrates well how the drive axis  10  extends through the housing  6  and engages the rotor  4 . Further the second extension  99  comprising the sensor element  101  that is configure to engage and interact with the sensor  43  is also well visible in  FIG. 8 . 
       FIG. 9  illustrates a perspective view of a different embodiment of the peristaltic pump  101 , whereby the housing is removed for illustrative purposes. The difference concerns the opening and closing mechanism  108  and the rotating shaft  160 . Note that only the parts that differ from the previous embodiment shown in  FIGS. 1 to 8  will be described. The slider  20  remains unchanged for instance. Some elements that are connected to the slider  20  however differ from the embodiment shown previously, such as the pin  54  and the post  52 . The shaft  160  is divided in two shaft parts  160   a ,  160   b , each of the parts  160   a ,  160   b  is embedded with one end in the housing (not shown) and with another end in a disc-shaped piece  161   a ,  161   b , which disc-shaped pieces  161   a ,  161   b  each have a diameter greater than the shaft parts  160   a ,  160   b . The shaft parts  160   a ,  160   b  are further connected to the pivotable cover  22  via one end. The disc-shaped pieces  161   a ,  161   b , each comprise a hole  164  for receiving the corresponding shaft part end and the disc-shaped pieces  161   a ,  161   b  further each comprise a set screw  163  for clamping the respective disc shaped piece  161   a ,  161   b  to the corresponding shaft part  160   a ,  160   b  and shaft part end, respectively. 
     The disc-shaped pieces  161   a ,  161   b , each comprise a recess  165 . The recess  165  is located eccentric on the disc shaped pieces  161   a ,  161   b  and also eccentric versus the shaft parts  160   a ,  160   b , so that an eccentric shaft  166  or the like can be arranged within the recess  165  so that the eccentric shaft  166  extends between the two disc-shaped pieces  161   a ,  161   b . The eccentric shaft  166  may comprise a ball-bearing  167 , as illustrated in  FIG. 9  or another ring-shaped element (not shown) that can be rotated when the disc-shaped pieces  161   a ,  161   b  are rotated, for example upon opening or closing the pivotable cover  22 . The disc-shaped pieces,  161   a ,  161   b , the eccentric shaft  166  and the ball bearing  167  may together form the first extension  102  (c.f.  FIG. 8 ), as previously explained. 
     The shaft parts  160   a ,  160   b  may be partially flattened at their end engaging the disc-shaped pieces  161   a ,  161   b  so that the set screw  163  can engage a flattened surface  168  for better engagement. 
     Turning now to  FIG. 10 , the opening and closing mechanism  108  illustrated in  FIG. 9 , is further explained. The slider  20  still comprises the pin  54  as previously described and with the same function but the post  152  is designed in a different manner and does not comprise a chamfered free end any longer but rather a cylindrical shaped free end. 
       FIG. 10  further illustrates how the position of the eccentric shaft  166 ′, the ball bearing  167 ′ and the post  152 ′ change when the pivotable cover  22  is in the closed position (not shown). The positions of the eccentric shaft  166 ′, the ball bearing  167 ′ and the post  152 ′ are indicated with dashed lines. It can be seen that the centre of the shaft  166 ′ and the ball bearing  167 ′ is positioned above a top surface of the post  152 ′ when the pivotable cover  22  is in the closed position (not shown). This creates a force in a closing direction of the pivotable cover  22  and an operator will feel when the pivotable cover “clicks” in its closed position. The same will happen when the pivotable cover  22  is opened, the positioning of the centre of the shaft  166 ′ and the ball bearing  167 ′ versus the top surface of the post  152 ′ creates a “click” that can be felt by an operator. The “click” is generated when the ball bearing  167 ′ is transferring from the edge of the post  152 ′ to the side surface of the post  152 ′. The described positioning of the eccentric shaft  166 ′, the ball bearing  167 ′ and the top surface of the post  152 ′ leads to the outcome that an upper edge of the post  152 ,  152 ′ is pushing the ball bearing  167 ′ towards a closed position of the pivotable cover  22  and the housing  6 , respectively, when the pivotable cover  22  is in the closed position (not shown in  FIG. 10 ). 
     The interaction between the pin  54  and the eccentric shaft  166 ,  166 ′ and the ball bearing  167 ,  167 ′ is the same as previously described and concerns the movement of the slider  20  via the pin  54 , when the pivotable cover  22  is moved from the closed position to the open position via the disc-shaped pieces  161   a ,  161   b , the ball bearing  167  and the eccentric shaft  166 , respectively. 
       FIG. 11  illustrates a top down view on the opening and closing mechanism  108  described in connection with  FIGS. 9 and 10 . In  FIG. 11  the disc-shaped pieces  161   a ,  161   b , the shaft parts  160   a ,  160   b , the ball bearing  167 , the post  152  and the pin  54  are well illustrated. The pivotable cover  22  is in its closed position. From  FIG. 11  it is further visible that the second extension  199  interacting with the sensor  143  is positioned slightly different as in the embodiments shown in  FIGS. 1 to 8 . The second extension  199  is connected to the shaft  160  and the shaft part  160   b , respectively, so that it can make contact with the sensor  143 , which sensor  143  is now positioned above the shaft  160  close to the housing  6  (c.f.  FIG. 3 ), when the pivotable cover  22  reaches the closed position. The sensor  143  is mounted on an inside of the front portion  18 , such as the roof portion of the front portion  18 , and press fitted to it using one, two or more pins or the like and/or an adhesive. 
     As indicated above, the first extension  102  comprising a roller  122  explained referring to  FIG. 8 , can be seen as the shaft  166  and the two disc-shaped pieces  161   a ,  161   b . The roller  122  may be seen as the ball bearing  167 . Thus the term first extension  102  also covers the solution of the opening and closing mechanism  108  shown in  FIGS. 9 to 11 . 
     As mentioned herein the elastic elements  24 ,  74  may be springs, rubber elements or other kind of dampers that are elastic. Further also the various adjustment elements  64 ,  72  may be screws, or other types of adjustable elements such as gear racks or the like. 
     The invention has now been described referring to a specific embodiment. The skilled person may however conceive that certain elements or mechanisms of the peristaltic pump may be designed differently. Such different designs are considered to fall within the scope of the present invention.