Patent Publication Number: US-2018051687-A1

Title: Tube Pump and Tube Stabilizer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. Ser. No. 13/472,593 filed May 16, 2012, which is a Continuation Application of U.S. Ser. No. 13/470,134 filed May 11, 2012, now U.S. Pat. No. 9,175,678 issued Nov. 3, 2015, which is a Continuation-in-Part of International Application No. PCT/JP2010/070143 filed Nov. 11, 2010, which claims priority from Japanese Patent Application Nos. 2009-258648, filed Nov. 12, 2009 and 2010-144713, filed Jun. 25, 2010. The entire disclosure of the prior applications is hereby incorporated herein by reference herein its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates a tube pump configured to move a roller pressing a tube along the tube and thereby to transport liquid in the tube by a peristaltic motion of the tube. 
     BACKGROUND 
     As an apparatus for transporting a relatively small amount of liquid, a tube pump configured to move a roller pressing a tube along the tube and thereby to transport liquid in the tube by a peristaltic motion of the tube has been widely used, as described, for example, in U.S. Pat. No. 5,356,267 (hereafter, referred to as patent document #1). 
       FIG. 10  is a side cross section of a conventional tube pump. As shown in  FIG. 10 , a tube pump  201  includes a drive motor  210 , a gear box  220  and a pump main body  300 . A rotation shaft  211  of the drive motor  210  is connected to the gear box  220 . The gear box  220  transmits a rotational motion of the drive shaft  211  to an output shaft  221  of the gear box  220  while decelerating the rotational motion of the rotation shaft  211 . 
     The pump main body  300  includes a cap  310 , a rotor  320  and a base  340 . The cap  310  includes a cylindrical inner surface  311 . A tube  360  of the tube pump  201  is arranged along the inner surface  311  of the cap  310 . 
     The rotor  320  includes a rotor main body  321 , a roller  322  and a roller pressure member  323 . The rotor main body  321  includes a circular plate  321   g  and a main support shaft  321   f  extending from the central part of the circular plate  321   g  to the cap  310 . The roller pressure member  323  is a member having a shape of a circular plate and is arranged on the cap  310  side with respect to the rotor main body  321 . The roller pressure member  323  holds the roller  322  between the rotor main body and the roller pressure member  323 . The rotor  321  is supported to be rotatable with respect to the cap  310 , and is configured such that the roller  322  rotates along the inner surface  311  of the cap  310  by rotating the rotor  320 . When the rotor  320  rotates, the tube  360  is pressed between the roller  322  and the inner surface  311  of the cap  310  to produce a peristaltic motion and thereby the liquid in the tube  360  is transported. 
     The base  340  is fixed to the gear box  220  with a bolt (not shown). The cap  310  is detachably attachable to the base  340 . When the cap  310  accommodating the tube  360  and the rotor  320  is attached to the base  340 , the output shaft of the gear box  220  engages with the rotor main body  321 , and it becomes possible to rotate the rotor  320  by driving the drive motor  210 . 
     In a tube pump in which liquid in a tube is transported by moving a roller, which presses a flexible tube to be a flat shape, along the tube, sometimes the tube is pulled in the moving direction of the roller by being pressed by the roller. If pulling-in of the tube occurs, the extra length of the upper side tube gradually decreases, and thereby it becomes necessary to periodically conduct a re-stretching work for the tube. Therefore, a tube fixing member for fixing the upstream part and/or the downstream part of the tube to the tube pump main body is used. Japanese Patent Provisional Publication No. 2007-198150A (hereafter, referred to as patent document #2) discloses a tube pump which uses a tube fixing member (a holder  4   d ) formed by bending a wire in a gate shape. In the tube pump disclosed in patent document #2, two circular holes are formed in a front surface of a main body housing which accommodates a drive motor, and a tube is fixed between the tube fixing member and the main body housing by inserting the both ends of the tube fixing member into the two circular holes. Regarding the tube fixing member of the patent document #2, the number components is small (configured by a single component), and the fixing/releasing of the tube can be achieved by insertion or drawing (i.e., a single step) of the tube fixing member. Therefore, the tube fixing member is excellent in regard to the part cost and the workability. 
     SUMMARY 
     In the conventional tube pump shown in  FIG. 10 , a projection  341  protruding to the cap  310  side is formed on the base  340 . The projection  341  is provided to seal a space between the roller  322  and the inner surface  311  of the cap  310 , so that the tube  360  does not drop off the roller  322  even when the tube  360  moves to the base  340  side. 
     As described above, in the conventional tube pump, the projection  341  which is a mechanism for preventing dropping-off of the tube  360  is provided on the base  340 . Since the projection  341  is inserted into the space between the roller  322  and the inner surface  311  of the cap  310 , it is required to secure a large space between the roller  322  and the inner surface  311  of the cap  310 . That is, in order to suppress the dropping-off of the tube in the conventional tube pump, the size of the tube pump inevitably increases, and it is difficult to downsize the tube pump. 
     Furthermore, in the conventional tube pump  201 , there is a possibility that the tube  360  contacts the projection  341  and thereby a force for drawing the cap  310  from the base  340  occurs, and the cap  310 , particularly a nail  314  for engaging the cap  310  with the base  340 , is damaged due to the force. 
     The present invention is made to solve the above described problem. That is, the first object of the invention is to provide a compact tube pump in which damage of a cap is hard to occur. 
     Furthermore, the conventional pump  201  shown in  FIG. 10  is configured such that a high degree of torque applies to the main support shaft  321   f . Therefore, the main support shaft  321   f  is formed to have a large diameter. Therefore, in order to decrease the size of the tube pump  201 , the diameter of the roller  322  is inevitably decreased. If the diameter of the roller  322  is small, the contact surface between the roller  322  and the tube  360  also decreases. As a result, the load applies to the tube in a concentrated manner, and fatigue of the tune occurs in a relatively short time period. 
     The present invention is made to solve the above described problem. That is, the second object of the present invention is to provide a compact tube pump in which a large diameter of a roller pressing a tube can be secured. 
     Furthermore, the conventional tube pump  201  shown in  FIG. 10  is configured such that the output shaft  221  of the gear box  220  can be fixed to an engagement hole  321   e  formed in the circular plate  321   h  of the rotor main body  321 . In order to transmit a high degree of torque from the output shaft  221  to the rotor main body  321 , the cross sectional shape of each of the output shaft  221  and the engagement hole  321   e  is non-circular. Therefore, when the output shaft  221  of the gear box is attached to the rotor, positions of these members need to be registered. In order to conduct such registration effectively, it is preferable that the registration is conducted in a state where the gear box  220  is detached from the engagement hole  321   e  to some extent. That is, it is preferable that the size in the length direction of the output shaft  221  and the engagement hole  321   e  is sufficiently large. When the size of the tube pump can be set to be large, it is also possible to set the size in the length direction of the output shaft  221  and the engagement hole  321   e  to be large. However, in a compact tube pump, it is impossible to set the size in the length direction of the output shaft  221  and the engagement hole  321   e  to be large. Therefore, in order to fit the output shaft  221  into the engagement hole  321   e  in the tube pump  201  shown in  FIG. 10 , it is necessary to conduct the registration of the output shaft  221  and the rotor main body  321  in a state where the cap  310  is situated close to the base  340 . Since such registration work is not easy, the conventional tube pump takes a long time for assembling 
     The present invention is made to solve the above described problem. That is, the third object of the present invention is to provide a tube pump in which a drive unit including a drive motor and a gear box can be connected to a roller by a relatively easy work. 
     With regard to the tube pump described in the patent document #2, the following problem is considered. That is, in the conventional fixing manner disclosed in the patent document #2, the force for holding the tube with a tube fixing member (i.e., the deforming amount of the tube) fluctuates depending on the inserting amount of the both ends of the tube fixing member to circular holes. It is difficult to precisely control the inserting amount of the tube fixing member to the circular hole, and therefore a large degree of variations of the holding force of the tube by the conventional fixing member described in the patent document #2 cannot be avoided. Therefore, a problem frequently arises that the pulling-in of the tube occurs due to insufficient fixing of the tube by the tube fixing member, and decrease of the flowing amount and the deterioration and the damage of the tube occur due to excessive pressing of the tube. 
     To achieve the first object of the invention, a tube pump according to the invention includes a rotor configured to have a roller and to hold the roller to be able to make an orbital motion along the inner circumferential surface of the cap, and the rotor includes a disk part which holds the roller on a base side, and a tube press member that engages with the disk part so that the tube does not move to the base side with respect to the disk part, seals a gap formed with respect to the inner circumferential surface of the cap, and is capable of rotating along an outer circumferential part of the disk part is provided at the outer circumferential part of the disk part. 
     Since, according to the above described configuration, dropping-off of the tube is prevented by the tube press member attached to the rotor, there is no necessity to provide a mechanism for preventing dropping-off of the tube on the base. Therefore, a compact tube pump can be realized. When the tube contacts the tube press member, the tube press member stays still because of the frictional force acting between the tube and the tube press member. Therefore, even if the rotor rotates, the tube is not pulled by the tube press member, and therefore, the load acting on the tube and the tube press member becomes small. There is a possibility that, in a configuration where the dropping-off of the tube is suppressed by the rotor itself, the tube is pulled by the rotor when the tube contacts the rotor and thereby the tube is damaged. By contrast, according to the invention, the tube is not pulled, and the lifetime of the tube becomes long. 
     A step part may be formed on an outer circumferential surface of the disk part such that a diameter of the disk part is made larger on the base side, and the tube press member may be a ring-shaped member having an inner circumferential surface on which a step part engaging with the step part of the disk part is formed. 
     The rotor may include a roller presser member that holds the roller while sandwiching the roller between the roller presser member and the disk part. In this case, a rotor support shaft may be formed on the cap to extend toward the base, a main support shaft may be formed at a central part of the disk part to extend toward the roller presser member, and a bearing hole may be formed in each of the roller presser member and the main support shaft so as to enable the rotor to rotate around the rotor support shaft. 
     The rotor may include a roller presser member that holds the roller between the roller presser member and the disk part, a main support shaft may be formed at a central part of the disk part to extend toward the roller presser member so that a tip of the main support shaft contacts the roller presser member, and a rib may be formed between the disk part and the main support shaft. 
     An engagement part that engages with the roller presser member and transmits a rotational motion of the disk part to the roller presser member may be formed on the rib. 
     The engagement part of the rib may be a projection that protrudes toward the roller presser member. In this case, a hole is formed in the roller presser member to accommodate the projection. 
     A hole may be formed at a central part of the roller to extend along an axis direction, and a roller support shaft that extends toward the roller presser member and is accommodated in the hole of the roller may be formed on the disk part so as to rotatable support the roller. 
     The tube pump may further include a drive unit that is fixed to the base and rotates the rotor so that the roller makes the orbital motion, and a joint shaft that transmits a rotational motion of an output shaft of the drive unit to the rotor. In this case, the rotor may include a roller presser member that holds the roller between the roller presser member and the disk part, a main support shaft may be formed at a central part of the disk part such that the main support shaft extends toward the roller presser member and a tip of the main support shaft contacts the roller presser member, a positioning shaft part having a non-circular cross section may be formed on a rotor side end portion of the joint shall, and an engagement shaft part that has a non-circular cross section and has a diameter larger than that of the positioning shaft part may be formed on a drive unit side portion of the joint shaft with respect to the positioning shaft part. A positioning hole that is capable of engaging with the positioning shaft part may be formed in the main support shaft, and an engagement hole that is capable of engaging with the engagement shaft part may be formed in the disk part. 
     The positioning shaft part may be formed such that a cross section radially extending from an center axis line of the joint shaft has a shape of a letter “Y”. 
     The engagement shaft part may have a cross section having a triangular shape. 
     On a part of an outer circumferential surface of the cap, a nail may be formed to protrude outward in a radial direction, a recession in which the cap is accommodated may be formed on the base, and a nail may be formed on the recession of the base such that the nail of the base engages with the nail of the cap to prevent the cap from dropping off the base. In this case, the nail of the base contacts the outer circumferential surface of the cap, and the cap is reinforced by the nail of the case from an outside in the radial direction. 
     An engagement projection may be formed on one of the nail of the base and the outer circumferential surface of the cap with which the nail of the base contacts, and an engagement recession may be formed on the other of the nail of the base and the outer circumferential surface of the cap. 
     The engagement projection may be formed in a shape of a pin extending in an axis direction of the cap. 
     To achieve the above described second object, the tube pump according to the invention includes a rotor configured to have a roller and to hold the roller to be able to make an orbital motion along the inner circumferential surface of the cap. The rotor includes a disk part which holds the roller on a base side, and a roller presser member that holds the roller between the roller presser member and the disk part. A main support shaft is formed at a central part of the disk part such that the main support shaft extends toward the roller presser member and a tip of the main support shaft contacts the roller presser member, and a rib is formed between the disk part and the main support shaft. 
     According to the above described tube pump, since the main support shaft is reinforced by the rib, it becomes possible to secure a large diameter for the roller while decreasing the diameter of the main support shaft even when the tube pump is formed to be compact. 
     To achieve the above described third object, the tube pump according to the invention includes a rotor configured to have a roller and to hold the roller to be able to make an orbital motion along the inner circumferential surface of the cap. The tube pump includes a base to which the cap is attached, a drive unit that is fixed to the base and rotates the rotor so that the roller makes the orbital motion, and a joint shaft that transmits a rotational motion of an output shaft of the drive unit to the rotor. The rotor includes a disk part which holds the roller on a disk side, and a roller presser member that holds the roller between the roller presser member and the disk part. A main support shaft is formed at a central part of the disk part such that the main support shaft extends toward the roller presser member and a tip of the main support shaft contacts the roller presser member, a positioning shaft part having a non-circular cross section is formed on a rotor side end portion of the joint shaft, an engagement shaft part that has a non-circular cross section and has a diameter larger than that of the positioning shaft part is formed on a drive unit side portion of the joint shaft with respect to the positioning shaft part, a positioning hole that is capable of engaging with the positioning shaft part is formed in the main support shaft, and an engagement hole that is capable of engaging with the engagement shaft part is formed in the disk part. 
     According to the above described tube pump, the drive unit can be coupled to the rotor by simply moving the cap to the base in a state where the positioning shaft part of the joint shaft and the positioning hole formed in the inside of the main support shaft engage with each other. The engagement between the positioning shaft part and the positioning hole can be conducted in a state where the cap is away from the base. Therefore, according to the invention, the drive unit can be easily coupled to the rotor even when the tube pump is formed to be compact. 
     In view of the above described circumstances, a tube fixing member according to an embodiment of the invention is provided. The tube fixing member according to an embodiment of the invention is a tube fixing member for fixing a flexible tube to a housing of a tube pump, wherein the tube pump transports liquid in the flexible tube arranged along a wall surface by continuously pressing and flattening a part of the flexible tube to cause elastic deformation through use of a roller moving along the wall surface. The tube fixing member includes a first holding part which sandwiches the flexible tube between the first holding part and the housing of the tube pump, and an engagement part that protrudes from the first holding part, engages with the housing of the tube pump, and presses the first holding part against the housing of the tube pump. 
     By using the tube fixing member having the above described configuration, it becomes possible to hold the tube by a constant appropriate holding force. Therefore, a problem that the tube is excessively deformed and is damaged or inversely pulling-in of the tube cannot be securely prevented due to the excessively weak holding force does not occur. Furthermore, since the attaching/detaching of the tube fixing member can be achieved by a one-touch operation, it becomes possible to effectively perform assembling and maintenance work for the tube pump. 
     A recessing part which contacts the flexible tube may be formed on the first holding part. The recessing part may be formed to be a recessed curved surface having a curvature substantially equal to a curvature of a side surface of the flexible tube. 
     By providing such a recessing part, precise positioning for the flexible tube can be realized. In particular, when the flexible tube is formed of a slender tube or of soft material, the lifetime of the flexible tube can be enhanced. When the recessing part is formed to be a recessed curved surface having a curvature substantially equal to a curvature of a side surface of the flexible tube, the holding force acting on the side surface of the flexible tube becomes uniform, and the stress concentration does not occur. Therefore, the lifetime of the flexible tube can be further enhanced. 
     It is preferable that the engagement part may be formed to protrude in a direction to which the recessing part points. At a tip portion of the engagement part in a protruding direction, a second engagement mechanism is formed to engage with a first engagement mechanism formed on the housing of the tube pump. For example, the first engagement mechanism and the second engagement mechanism are an engagement projection and an engagement nail, respectively, or are an engagement nail and an engagement projection, respectively. 
     With this configuration, it becomes possible to attach the tube fixing member to the housing with a strong force. 
     The recessing part may include a first recession which contacts a first end of the flexible tube, and a second recession which contacts a second end of the flexible tube. In this case, it is preferable that the engagement part protrudes from an intermediate position between positions of the first recession and the second recession. 
     By employing such a configuration where the both ends of the flexible tube is fixed by one tube fixing member, it becomes possible to considerably decrease the work man-hour for attaching the tube fixing member in addition to achieving reduction of the number of parts and downsizing. 
     It is preferable that the engagement part includes a first part protruding perpendicularly from a first surface of the first holding part, and a second part protruding, from a tip of the first part, in a frontward direction to which the recessing part points, and a most frontward surface of the first part is formed to have an offset to a back side with respect to a most frontward surface of the first holding part. 
     By thus arranging the most front surface of the first part to have an offset to the back side with respect to the most front surface of the first holding part, it becomes possible to securely engage the first part with a rear end of a support part (e.g., a flat plate pan). As a result, the attaching work of the tube fixing member is made more efficient, and the tube can be stably held by the tube fixing member. 
     The tube fixing member may further include a second holding part which is arranged between the first holding part and the housing of the tube pump and which sandwiches the flexible tube between the second holding part and the first holding part. 
     By employing such a second holding part, it becomes possible to hold the flexible tube without causing the shearing force. Therefore, a problem that the tube buckles due to the shearing force can be prevented, particularly in the case where a slender tube or a tube formed of sort material is used. Furthermore, it becomes possible to arrange the tube at a more appropriate position in accordance with the shape and the size of the tube. 
     According to an embodiment of the invention, a tube pump including the housing to which the above described tube fixing member can be attached is provided. The housing of the tube pump according to an embodiment of the invention includes a support part which supports the first holding part, and a first engagement mechanism which engages with the second engagement mechanism formed on the engagement part of the tube fixing member. 
     Typically, the support part includes a first flat plate part which is sandwiched between the first holding part and the engagement part of the tube fixing member. The support part may include a second, flat plate part which is formed to be parallel with the first flat plate part and which sandwiches the first holding part of the tube fixing member between the second flat plate part and the first flat plate part, 
     The tube pump may further include a drive unit; and a pump cartridge which is detachably attachable to the drive unit. Typically, the pump cartridge includes a roller, a flexible tube, and a pump cassette on which a wall surface for pressing and flattening the flexible tube between the wall surface and the roller is formed. In this case, it is preferable that the housing is the pump cassette. 
     The tube pump having the pump cartridge which is detachably attachable to the drive unit is able to considerably enhance the maintenance workability of a pump mechanism (the pump cartridge) which is more frequently subjected to the maintenance. When the present invention is applied to the tube pump configured as described above, the workability for attaching the pump cartridge to the drive unit can be enhanced by fixing an end of the flexible tube to the pump cassette which is the housing of the pump cartridge. 
     The tube pump further includes a rotor which rotatably supports a plurality of rollers. In this case, the wall surface is a cylindrical first inner wall surface formed on the pump cassette, and on a second inner wall surface of the pump cassette formed to be substantially perpendicular to the first inner wall surface, a rotor support shaft which rotatably supports the plurality of rollers is formed to extend along a center axis of the cylindrical first inner wall surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a tube pump according to a first embodiment of the invention. 
         FIG. 2  is a side cross section of the tube pump according to the first embodiment. 
         FIG. 3  is an exploded view of the tube pump according to the first embodiment. 
         FIG. 4  is a perspective view of a joint shaft of the tube pump according to the first embodiment. 
         FIG. 5  is a front view of the joint shaft of the tube pump according to the first embodiment. 
         FIG. 6  is a rear view of a rotor body of the tube pump according to the first embodiment. 
         FIG. 7  is a perspective view of the rotor body of the tube pump according to the first embodiment. 
         FIG. 8  is a side cross section of the tube pump of another example of the first embodiment. 
         FIG. 9  is a side cross section of the tube pump of another example of the first embodiment. 
         FIG. 10  is a side cross section of a conventional tube pump. 
         FIG. 11  is an exploded view of a tube pump according to a second embodiment. 
         FIG. 12  is a front view of the tube pump according to the second embodiment. 
         FIG. 13  is a vertical cross section of the tube pump according to the second embodiment. 
         FIG. 14  is a rear view of a pump cassette of the tube pump according to the second embodiment. 
         FIG. 15  is a bottom view of the pump cassette of the tube pump according to the second embodiment. 
         FIG. 16  is an outer appearance of a tube stabilizer according to the second embodiment, in which  FIG. 16( a )  is a rear view,  FIG. 16( b )  is a top view,  FIG. 16( c )  is a front view and  FIG. 16( d )  is a side view. 
         FIG. 17  shows top views of variations of the tube stabilizer according to the second embodiment. 
         FIG. 18  is an explanatory illustration for explaining a detaching method of the tube stabilizer according to the second embodiment. 
         FIG. 19  illustrates a variation of the tube stabilizer according to the second embodiment. 
         FIG. 20  illustrates a variation of the tube stabilizer according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the following, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. 
     First Embodiment 
     Hereafter, a first embodiment according to the invention will be described in detail with reference to the accompanying drawings.  FIGS. 1 and 2  respectively illustrate a front view and a side cross sectional view of a tube pump according to the first embodiment.  FIG. 3  is an exploded view of the tube pump according to the embodiment. As shown in  FIGS. 2 and 3 , the tube pump  1  according to the embodiment includes a drive motor  10 , a gear box  20  and a pump body  100 . 
     In the following explanation, the side on which the pump body  100  is situated is referred to as a “near side” (the front side in  FIG. 2 , the left side in  FIG. 2 , and the lower left side in  FIG. 3 ), and the side on which the drive motor  10  is situated is referred to as a “back side” (the rear side in  FIG. 2 , the right side in  FIG. 2 , and the upper right side in  FIG. 3 ). In addition, the direction pointing from the near side to the back side and the direction pointing from the back side to the near side are defined as a depth direction. 
     The pump body  100  includes a cap  110 , a rotor  120 , a tube press ring  130  ( FIGS. 2 and 3 ), a base  140 , a fixing plate  150  and a plate holding cylinder  170 . 
     As shown in  FIGS. 2 and 3 , the fixing plate  150  is held by being sandwiched between the base  140  and the plate holding cylinder  170 . That is, by fixing the plate holding cylinder  170  to the base  140 , the fixing plate  150  is fixed to the base  140 . As shown in  FIGS. 1 and 3 , a pair of through holes  151  is formed in the fixing plate  150 . When the tube pump  1  is fixed to, for example, a frame of an apparatus in which the tube pump  1  is used, the fixing plate  150  is fixed to the frame by inserting bolts into the through holes  151 . 
     As described above, in the embodiment, the fixing plate  150  for fixing the tube pump  1  can de detached. Therefore, by using the fixing plate  150  having an appropriate shape in accordance with the shape of a frame to which the tube pump  1  is to be attached, it becomes possible to attach the tube pump  1  to various types of apparatuses. 
     As shown in  FIGS. 1 and 2 , an inner circumferential surface  111  of the cap  110  is formed to be a cylindrical surface, and a tube  160  is arranged along the inner circumferential surface  111  (i.e., the long axis of the tube  160  is substantially equal to the circumferential direction of the inner circumferential surface  111 ). As shown in  FIG. 1 , a first opening  112   a  and a second opening  112   b  are formed at a lower portion of the cap  110 , and a first end  161  and a second end  162  of the tube  160  respectively protrude to the outside of the cap  110  via the first opening  112   a  and the second opening  112   b.    
     As shown in  FIG. 3 , the rotor  120  includes a rotor body  121 , three rollers  122 , and a rotor presser member  123 . As shown in  FIG. 2 , at a central part of a ceiling  113  situated on the near side in the cap  110 , a rotor support shaft  114  is formed to extend from the near side to the back side. Engagement holes  121   a  and  123   a  into which the rotor support shaft  114  is inserted are respectively formed in the rotor body  121  and the rotor presser member  123 , and the rotor body  121  and the rotor presser member  123  are rotatably supported by the rotor support shaft  114 . 
     The rotor body  121  includes a disk part  121   g  and three roller support shafts  121   b  extending from a front surface of the disk part  121   g  to the near side. The roller support shafts  121   b  are formed to be along a circumference having its center at the engagement hole  121   a . The engagement hole  121   a  of the rotor body  121  is formed in the inside of a main support shaft  121   f  extending from a central part of the front surface of the disk part  121   g  to the near side. The roller  122  has a shape of a column, and at a central part of one end surface (back side)  122   a , a hole  122   c  is formed to extend toward the other end surface (near side)  122   b . The diameter of the hole  122   c  is determined to be able to slidably accommodate the roller support shaft  121   b  of the rotor body  121 . Furthermore, a cylindrical projection  122   d  is formed in the end surface  122   b  of the roller  122 . On a back side end face  123   b  of the rotor presser member  123 , three recessions  123   c  each of which is able to slidably accommodate the projection  122   d  of the roller  122  are formed along a circumference having a center at the engagement hole  123   a.    
     By inserting the roller support shafts  121   b  of the rotor body  121  into the holes  122   c  of the rollers  122 , accommodating the projections  122   d  of the rollers  122  in the recessions  123   c  of the rotor presser member  123  and further inserting the engagement holes  123   a  and  121   a  of the rotor presser member  123  and the rotor body  121  into the rotor support shaft  114  of the cap  110 , the entire rotor  120  becomes able to rotate about the rotor support shaft  112  and each of the rollers  122  becomes able to rotate around the roller support shaft  121   b  of the rotor body  121 . At this time, the main support shaft  121   f  of the rotor body  121  contacts the rotor presser member  123 . 
     As shown in  FIGS. 1 and 2 , the tube  160  is pressed and flattened between the rollers  122  and the inner circumferential surface of the cap  110 , and when the rotor  120  rotates around the rotor support shaft  114  of the cap  110 , the rollers  122  cause an orbital motion along the inner circumferential surface  111  of the cap  110  while pressing and flattening the tube  160 . As a result, the tube  160  causes a peristaltic motion, and the content in the tube  160  moves. For example, when the rotor  120  is rotated in the clockwise direction in  FIG. 1 , the content of the tube  160  is transported from the first end protruding from the first opening  112  situated at the lower left toward the second end  162  protruding from the second opening  112   b  situated at the lower right. Thus, the content or the tube  160  can be transported by driving the rotor  120 . 
     The cap  110  is configured to be fixed to the base  140 . When the cap  110  is fixed to the base  140 , the rotor  120  is held by being sandwiched between the cap  110  and the base  140 . 
     As shown in  FIG. 2 , on the outside of the rotor body  121  in the radial direction, the tube press ring  130  having the diameter slightly larger than that of the rotor body  121  is arranged. On an inner circumferential surface  131  of the tube press ring  130 , a step  132  is formed such that a small diameter part  132   a  is situated on the near side and a large diameter part  132   n  is situated on the back side. On a cylindrical outer circumferential surface  121   c  of the rotor body  121 , a step  121   d  is formed such that a small diameter part  121   d   1  is situated on the near side and a large diameter part  121   d   2  is situated on the back side. The diameter of the small diameter part  132   a  of the tube press ring  130  is slightly larger than the diameter of the small diameter part  121   d   1  of the rotor body  121  and is smaller than the large diameter part  121   d   2 . Furthermore, the large diameter part  132   b  of the tube press ring  130  is slightly larger than the diameter of the larger diameter part  121   d   2  of the rotor body  121 . Therefore, in a state where the tube press ring  130  is attached to the rotor body  121 , the step  121   d  of the rotor body  121  engages with the step  132   b  of the tube press ring  130 , and as a result the tube press ring  130  does not move to the back side of the rotor body  121  and the tube press ring  130  is able to rotate while sliding on the rotor body  121 . In a state where the cap  110  and the tube press ring  130  reattached to the rotor body  121 , the centers of the outer circumferential surface  121   c  of the rotor body  121  and the inner circumferential surface  131  of the tube press ring  130  substantially coincide with the center axis of the rotor support shaft  114  of the cap  110 . 
     As shown in  FIG. 2 , the tube press ring  130  is arranged to seal the gap between the rollers  122  of the rotor  120  and the inner circumferential surface  111  of the cap  110 . With this configuration, when the tube pump  1  operates, the tube  160  is prevented from running off the gap between the rollers  122  and the inner circumferential surface  111  of the cap  110  even if the tube  160  moves to the back side. 
     In a configuration where the tube pump  1  does not have the tube press ring  130  and instead the disk part  121   g  of the rotor body  121  is formed to seal the gap between the rollers  122  and the inner circumferential surface  111  of the cap  110 , there is a possibility that, when the tube  160  moves to the back side and thereby contacts the disk part  121   g  of the rotor body  121 , the tube  160  is drawn in the direction of the orbital motion of the rollers  122  by the frictional force acting on the disk part  121   g  and the tube  160 , and the tube is damaged. 
     By contrast, in the tube pump  1  according to the embodiment, the tube press ring  130  capable of rotate with respect to the disk part  121   g  of the rotor body  121  serves to prevent the tube  160  from running off the gap between the rollers  122  and the inner circumferential surface  111  of the cap  110 . In such a configuration, when the tube  160  moves to the back side and contacts the tube press ring  130 , the tube press ring  130  stays still without following the rotation of the rotor body  121  due to the frictional force acting between the tube  160  and the tube press ring  130 , and thereby the tube  160  is prevented from being drawn in the direction of the orbital motion of the rollers  122  by the rotation of the rotor  120  and is prevented from being damaged. 
     Since, as described above, the tube pump  1  according to the embodiment is configured such that the gap between the rollers  122  of the rotor  120  and the inner circumferential surface  111  of the cap  110  is sealed by the tube press ring  130  attached to the rotor body  121 , the tube  160  can be installed in the tube pump  1  through an easy work in which the rotor  120  is formed by combining the rollers  122  and the rotor presser member  123 , the tube  160  is arranged around the rollers  122  of the rotor  120 , and then the tube  160  is pressed into the cap  110  together with the rotor  120  and the tube press ring  130 . 
     Next, an attachment mechanism for attaching the cap  110  to the base  140  is explained. As shown in  FIGS. 1 to 3 , at the back side end portion of an outer circumferential surface  116  of the cap  110 , four nails  115  protruding outward in the radial direction and in a shape of a flange are formed at constant intervals (i.e., every 90 degrees). A recession  141  for accommodating the back side part and the nails  115  of the cap  110  is formed on the base  140 , and at the near side end of an inner circumferential surface  142  of the recession  141 , four nails  143  protruding inward in the radial direction are formed at constant intervals (i.e., every 90 degrees). Tips of the four nails  115  of the cap  110  in the radial direction are arranged along a circumference concentric with the outer circumferential surface  116  of the cap  110 , and the diameter of the circumference is slightly smaller than the inner circumferential surface  142  of the case  140 . Tips of the four nails  143  of the base  140  are arranged along a circumference concentric with the inner circumferential surface  142  of the case  140 , and the diameter of the circumference is substantially equal to the diameter of the outer circumferential surface of the cap  110  and is smaller than the circumference on which the four nails  115  are positioned. Furthermore, the size of the nail  115  of the cap  110  in the circumferential direction is sufficiently smaller than the interval between the nails  143  of the base  140  in the circumferential direction (i.e., the length, in the circumferential direction, of each of four regions where the nails  143  are not provided on the inner circumferential surface  142 ). 
     The cap  110  is attached to the base  140  by inserting the nails  115  to the recession  141  of the base so as not to interfere with the nails  143  of the base  140 , by rotating the cap  110  about the rotor support shaft  114  of the cap  110  in the clockwise direction in  FIG. 1 , and by moving the nails  115  of the cap  110  to the positions at which the nails  115  are aligned with the nails  143  of the base  140  in the depth direction. In the state where the nails  115  of the cap  110  are aligned with the nails  143  of the base  140  in the depth direction, the nails  115  of the cap  110  engage with the nails  143  of the base  140 , and therefore the cap  110  is not removed from the base  140  even if the cap  110  is drawn from the base  140  to the near side. 
     In the tube pump  1 , the tube  160  is constantly pressed against the inner circumferential surface  111  of the cap  110  by the rotor  120 , and a load pointing outward in the radial direction is applied constantly to the cap  110 . As described above, in this embodiment, the nails  143  of the base  140  contact the outer circumferential surface  116  of the cap  110  in the state where the cap  110  is attached to the base  140 . Therefore, the nails  143  reinforce the cap  110  from the outside in the radial direction, and deformation of the cap  110  by the load pointing to the outside in the radial direction can be suppressed. 
     At the near side portions of the nails  115  on the outer circumferential surface  116  of the cap  110 , engagement projections  117  each having a shape of a pin are provided to protrude outward in the radial direction and to extend in the depth direction ( FIGS. 1 and 3 ). On the nails  143  of the base  140 , engagement recessions  144  are formed to be recessed outward in the radial direction. At an end of the nail  143  of the base  140  in the circumferential direction, a slanting surface  145  is formed to become closer to the inner circumferential surface  142  of the case  140  toward the clockwise direction. Therefore, when the cap  110  is inserted into the recession  141  of the case  140  and then the cap  110  is rotated in the clockwise direction in  FIG. 1 , the engagement projections  117  of the cap  110  move along the slanting surfaces  145  of the nails  143  of the base  140  and are finally fitted into the engagement recessions  144 , respectively. In the state where the engagement projections  117  are fitted into the engagement recessions  144 , the engagement between the engagement projections  117  and the engagement recessions  144  are such that the cap  110  cannot be removed unless the cap  110  is rotated in the counter clockwise direction with a strong force. That is, thanks to the engagement between the engagement projections  117  and the engagement recessions  144 , the cap  110  is engaged with the base  140 . 
     As described above, in this embodiment, the cap  110  is locked to the base  140  by the engagement projections  117  provided on the outer circumferential surface  116  of the cap  110 . In the conventional structure where engagement projections or engagement recessions are formed on a nail which is a low rigidity part of a cap, a large load may be applied to the nail for engagement, and thereby the nail may be damaged. By contrast, since, according to the embodiment, the engagement projections  117  are provided on the outer circumferential surface  116  having a relatively high degree of rigidity, the cap  110  hard to be damaged when the cap  110  is attached. 
     At a portion of the other end (at the counterclockwise end portion in  FIG. 1 ) of the nail  143  in the circumferential direction on the inner circumferential surface of the base  140 , a stopper  146  having a smaller diameter is formed (see  FIGS. 1 and 3 ). In the case where the cap  110  is rotated in the clockwise direction in  FIG. 1  from the state where the engagement projections  117  are fitted into the engagement recessions  144 , even when the engagement between the engagement projections and the engagement recessions  144  is released, the nail  115  interferes with the stopper  146  and thereby the cap  110  is prevented from rotating in the clockwise direction further more. That is, the stopper  146  functions as a stopper for stopping the movement of the cap in the clockwise direction in  FIG. 1  from the state where the engagement projections  117  are filled into the engagement recessions  144 . 
     Although, in this embodiment, the engagement projections  117  are provided on the cap  110  and the engagement recessions are formed on the base  140 , engagement recessions formed to be recessed inward in the radial direction of the cap  110  may be provided on the cap  110 , and engagement projections protruding outward in the radial direction of the case may be provided on the base  140 . 
     Next, a mechanism for rotating the rotor  120  of the pump body  100  is explained. As shown in  FIG. 2 , a rotation shaft  11  of the drive motor  10  is connected to the gear box  20 . The gear box  20  transmits the rotational motion of the rotation shaft of the drive motor  10  to an output shaft  21  of the gear box  20  while decelerating the rotational motion. To the output shaft  21  of the gear box  20 , a joint shaft  30  for transmitting the rotational motion of the output shaft  20  to the rotor body  121  of the rotor  120  is connected. 
     Hereafter, a joint mechanism between the joint shaft  30  and the rotor body  121  is explained.  FIG. 4  is a perspective view of the joint shaft  30 .  FIG. 5  is a front view of the joint shaft viewed from the near side (the lower left side in  FIG. 4 ). As shown in  FIG. 4 , at a tip of the near side (i.e., the rotor body  121  side) portion of the joint shaft  30 , a positioning shaft part  31  having the cross section form in a shape of a letter “Y” (i.e., the shape in which arms  31   a ,  31   b  and  31   c  radially extend from a center axis line  30 A of the joint shaft) is formed. 
     At a portion adjoining the back side portion of the positioning shaft part  31  of the joint shaft  30 , an engagement shaft part  32  is formed. The engagement shaft part  32  includes flat surface parts  32   a   1 ,  32   a   2  and  32   a   3  formed by cutting a cylindrical shaft by planes which are perpendicular to directions in which the arms  31   a ,  31   b  and  31   c  of the positioning shaft part  31  extend, at the positions of the tips f the arms  31   a ,  31   b  and  31   c , respectively, and cylindrical surfaces  32   b   1 ,  32   b   2  and  32   b   3  respectively formed between the flat surface parts  32   a   1  and  32   a   2 , between the flat surface parts  32   a   2  and  32   a   3  and between the flat surface parts  32   a   3  and  32   a   1 . On the whole, the engagement shaft part  32  is formed to have a triangular cross section. 
     In this embodiment, the positioning of the joint shaft  30  around the shaft with respect to the rotor body  121  is performed by the positioning shaft part  31  arranged on the near side, and the joint shaft  30  and the rotor body  121  become able to rotate together by the engagement shaft part  32 .  FIG. 6  is a rear view of the rotor body  121 . As shown in the cross sectional view of  FIG. 2  and the rear view of  FIG. 6 , an engagement hole  121   e  for engaging with the engagement shaft is formed in the rotor body  121 . 
     As shown in the cross sectional view of  FIG. 2 , the engagement hole  121   e  is a hole having a step, and includes a positioning hole part  121   e   1  situated on the near side and an engagement hole part  121   e   2  situated on the back side. The engagement hole part  121   e   2  is formed to have a triangular cross section which is substantially equal to the engagement shaft part  32  of the joint shaft  30 , and the rotor body  121  and the joint shaft  30  become able to rotate together by the engagement between the flat surface parts  32   a   1 ,  32   a   2  and  32   a   3  of the engagement shaft part  32  (see  FIGS. 4 and 5 ) and the engagement hole part  121   e   2 . On the other hand, the positioning hole part  121   e   1  has a cross section having a shape of a letter “Y” which is substantially equal to the positioning shaft part  31  (see  FIGS. 4 and 5 ), and after inserting the positioning shaft part  31  to the positioning hole part  121   e   1 , the engagement shaft part  32  can be engaged with the engagement hole part  121   e   2  by only moving the joint shaft  30  to the rotor body  121  along the positioning hole part  121   e   1 . 
     After the tube  160  is attached to the position between the cap  110  and the rollers  122  (see  FIGS. 1 and 2 ), the cap  110 , the rotor  120 , the tube  160  and the tube press ring  130  form an integrated pump side unit by the frictional force acting between the cap  110 , the rollers  122  and the tube  160 . When the joint shaft  30  is attached to this unit, a gear box side unit is formed by first fixing the joint shaft  30  to the output shaft  21  of the gear box  30 , and then fixing the base  140  to the gear box  20  with a bolt (not shown). Then, the engagement shaft part  32  of the joint shaft  30  is engaged with the engagement hole part  121   e   2  of the rotor body  121 , and finally the cap  110  is fixed to the base  140 . 
     It is preferable that the positioning between the engagement shaft part  32  of the joint shaft  30  and the engagement hole part  121   e   2  of the rotor body  121  is performed in the state where the base  140  does not interfere with the cap  110  or the rotor body  121 , i.e., in the state where the cap  110  is away from the base  140  to some extent. As to a large size tube pump in which a larger size can be secured for the cap  110  and the rotor  120  in the depth direction, it is possible to perform the positioning in the state where the cap  110  is away from the base  140  to some extent by securing a long size for the engagement shaft part  32  (the engagement shaft part  32  functions as a positioning shaft part). However, as to a compact size tube pump in which a large size in the depth direction cannot be secured for the cap  110  and the rotor  120 , in the configuration where the positioning shaft part  31  is not provided on the joint shaft  30 , a large size cannot be secured for the engagement shaft  32  in the depth direction, and thereby it becomes necessary to perform the positioning while contacting the engagement shaft part  32  with the rotor body  121  and sliding them with respect to each other. Therefore, the cap  110  is inevitably situated near the base  140 . For this reason, the cap  110  or the rotor body  121  easily interfered with the base  140 , and therefore the positioning work for the engagement shaft part  32  of the joint shaft  30  and the engagement hole part  121   e   2  of the rotor body  121  was not easy. By contrast, according to the embodiment, since the positioning shaft part  31  is formed on the joint shaft  30 , the positioning work for the engagement shaft part  32  of the joint shaft  30  and the engagement hole part  121   e   2  of the rotor body  121  can be performed easily. Furthermore, since there is no necessity to transmit torque from the gear box  20  to the rotor  120 , it is not necessary to increase the diameter thereof. Therefore, the main support shaft  121   f  in which the positioning shaft part  31  is accommodated can be made slender. 
     Next, the shape of the rotor  121  is explained.  FIG. 7  is a perspective view of the rotor body  121  according to the embodiment. In this embodiment, as shown in  FIGS. 1, 2 and 7 , three ribs  121   h  are formed between the main support shaft  121   f  of the rotor body  121  and the disk part  121   g . As shown in  FIG. 1 , each of the three ribs is located between the rollers  122 . 
     On the near side surfaces of the ribs  121   h , engagement projections  121   i  are formed. As shown in  FIG. 2 , on the rotor presser member  123 , through holes  123   d  into which the engagement projections  121   i  are fit are formed. 
     In a configuration where the ribs  121   h  are not formed on the rotor body  121 , a large degree of torque is applied to the main support shaft  121   f . Therefore, it is necessary to thicken the main support shaft  121   f  so that the main support shaft  121   f  is not damaged. In this embodiment, the main support shaft  121   f  is reinforced by the ribs  121   h , and further the rotor presser member  123  is coupled to the ribs  121   h  via the engagement projections  121   i . Therefore, even if the main support shaft  121   f  is slender, the main support shaft  121   f  is not damaged. Since the main support shaft  121   f  can be made slender, it is possible to make the diameter of the roller support shaft  121   b  large. As described above, in this embodiment, the diameter of the roller support shaft  121   b  can be made large. Therefore, as shown in  FIG. 8 , in this embodiment, it is possible to support the roller  122  only by the roller support shaft  121   b  in a cantilever manner, without providing the projection  122   d  on the roller  122  as shown in a cross sectional view of  FIG. 8 . Alternatively, as shown in a cross sectional view of  FIG. 9 , the hole  122   c  of the roller  122  may penetrate through the roller  122 , and the roller support shaft  121   b  may be formed to protrude from the near side end surface  122   b  of the roller  122  and to be accommodated in the recess  123   c  of the rotor presser member  123  (i.e., the roller support shaft  121   b  also serves as the function of the projection  122   d ). 
     Since, in this embodiment, the diameter of the roller  122  can be made large, it becomes possible to make a contact area between the roller  122  and the tube  160  can be made large, and thereby the load applied to the tube  160  can be dispersed. As a result, stretching of the tube  160  becomes relatively small, and the tube  160  is not damaged easily (i.e., the lifetime of the tube  160  can be increased). 
     Since, in this embodiment, the range of the diameter of the available roller  122  is large, the roller  122  having an appropriate diameter can be used in accordance with the thickness, material or the wall thickness of the tube  160 . 
     As described above, according to the embodiment, the long lifetime tube pump in which the damage to the tube is hard to occur, the tube pump capable of securing the large diameter of the roller, and the tube pump in which the drive unit can be attached to the rotor though an easy work can be realized. 
     Second Embodiment 
     Hereafter, a second embodiment is explained in detail with references to the drawings. For convenience of explanations, to elements which are substantially the same as those of the first embodiment, the same reference numbers are assigned.  FIG. 11  is an exploded perspective view of the tube pump  1  according to the second embodiment of the invention.  FIGS. 12 and 13  are the front view and the vertical cross section of the tube pump  1 , respectively.  FIGS. 14 and 15  are the rear view and the bottom view of a pump cassette  110  shown in  FIG. 11 . 
     As shown in  FIG. 11 , the tube pump  1  includes the drive motor  10 , the gear box  20  and the pump body  100 . The torque of the axial output produced by the drive motor  10  is amplified by the gear box  20 , and is supplied to the pump body  100 . 
     In the following explanations. The pump body  100  side of the tube pump  1  (the lower left side in  FIG. 11 , the front side on the paper face of  FIG. 12 , and the left side of  FIG. 13 ) is defined as the “near side”, and the drive motor  10  side (the upper right side of  FIG. 11 , the rear side in  FIG. 12 , and the right side of  FIG. 13 ) is defined as the “back side”. In addition, the direction pointing from the near side to the back side and the direction pointing from the back side to the near side are defined as the depth direction. The upper side and the lower side in  FIGS. 12 and 13  are defined as the “upper side” and the “lower side”, respectively. 
     The pump body  100  includes a pump cassette  110 , the rotor  120 , the base  140 , the fixing plate  150 , the tube  160 , the plate holding cylinder  170  and a tube stabilizer (a tube fixing member)  230  according to the embodiment. A part of the tube  160  and the rotor  120  are arranged in an operation chamber surrounded by the pump cassette  110  and the base  140 . 
     The pump cassette  110  is a bowl-shaped member formed with transparent resin, such as PP (polypropylene), by injection molding. The material of the pump cassette  110  is not limited to the transparent resin, but various types of general structural materials may be used. However, by using the transparent resin, it becomes possible to easily observe the inner condition, and therefore maintenance can be enhanced. In the pump cassette  110 , the tube  160 , the rotor  120  and the tube stabilizer  230  are attached, and thereby a pump cartridge detachable attachable to the base  140  can be formed. Structures of parts of the pump cassette  110  are explained later. 
     The fixing plate  150  is formed of, for example, a metal plate, such as a steel plate, and is held while being sandwiched between the base  140  and the plate holding cylinder  170 . The side surface (outer circumferential surface) of the base  140  is formed to be a cylindrical surface, a step is formed at a midway point on the side surface, and the diameter of the back side portion thereof is smaller than that of the near side portion. On the back side portion of the outer circumferential surface of the base  140 , a male thread (not shown) is formed. The plate holding cylinder is a cylindrical member having the inner diameter which is substantially equal to the diameter of the back side portion of the outer circumferential surface of the base  140 , and a female thread (not shown) to be engaged with the male thread formed on the outer circumferential surface of the base  140  is formed on the inner surface of the plate holding cylinder  170 . The fixing plate  150  has a circular hole having the diameter equal to the diameter of the back side portion of the outer circumferential surface of the base  140 . When the base  140  is inserted into the circular hole of the fixing plate  150  to the back side, the step of the outer circumferential surface of the base  140  is hooked to the circular hole of the fixing plate  150 . Then, by screwing the plate holding cylinder  170  to the outer circumferential surface of the case  140  on which the male thread is formed, the fixing plate  150  is fixed to the base  140  while being sandwiched between the step of the outer circumferential surface of the base  140  and the plate holding cylinder  170 . By detaching the plate holding cylinder  170 , it is possible to detach the fixing plate  150  from the base  140 . 
     As shown in  FIGS. 11 to 13 , the pair of attachment holes  151  is formed in the fixing plate  150 . When the tube pump  1  is attached to, for example, a frame of an apparatus (e.g., a washing machine) to which the tube pump  1  is to be installed, the fixing plate is fixed to the frame by inserting bolts into the attachment holes  151 . 
     As described above, in this embodiment, the fixing plate  150  for fixing the tube pump  1  is detachable. Therefore, by using the fixing plate  150  having an appropriate shape for the frame to which the tube pump  1  is attached, it becomes possible to attach the tube pump  1  to various types of apparatuses. 
     The rotor  120  includes the rotor body  121 , three rollers  122  and the rotor presser member  123 . The three rollers  122  are rotatably supported around the axis thereof between the rotor body  121  and the rotor presser member  123 . As shown in  FIG. 13 , at the central part of a ceiling  119  situated on the near side in the pump cassette  110 , the rotor support shaft  114  is formed to extend to the back side. Engagement holes  121   a  and  123   a  into which the rotor support shaft  114  is inserted are respectively formed in the rotor body  121  and the rotor presser member  123 , and the rotor body  121  and the rotor presser member  123  are rotatably supported by the rotor support shaft  114 . 
     As shown in  FIGS. 12 to 14 , the inner surface having the cylindrical surface shape is formed on the pump cassette  110 , and the tube  160  is arranged along the inner surface  111  (specifically, the length direction is aligned along the circumferential direction of the inner surface  111 ). The tube  160  is pressed and flattened between the rollers  122  and the inner surface  111  of the pump cassette  110 , and when the rotor  120  rotates around the rotor support shaft  114  of the pump cassette  110 , the rollers  122  make the orbital motion along the inner surface  111  of the pump cassette  110  while pressing flattening the tube  160 . As a result, the tube  160  produces the peristaltic motion, and the content of the tube  160  moves. For example, when the rotor  120  is rotated in the clockwise direction in  FIG. 12 , the content of the tube  160  is sent out from the first end  161  situated lower left portion in  FIG. 12  to the second end  162  situated lower right portion in  FIG. 12 . As described above, by driving the rotor  120 , the content of the tube  160  can be sent out. 
     As shown in  FIGS. 14 and 15 , at the lower side of the pump cassette  110 , two flat plate parts  212  and  213  expanding in parallel with the paper face of  FIG. 15  are formed. A pair of grooves  212   a  and  212   b  and a pair of grooves  213   a  and  213   b  extending from the back side end to the near side are respectively formed in the flat plate parts  212  and  213 . The first end  161  and the second end  162  of the tube  160  are protruded from the operation chamber of the pump cassette  110  through the grooves  212   a  and  213  and the grooves  212   b  and  213   b , respectively. The width of each of the grooves  212   a ,  212   b ,  213   a  and  213   b  is set to be substantially equal to the outer diameter of the thickest one of the attachable tubes  160 . The position of the bottom of each groove (the nearest side end), is set such that, even when the tube  160  is pressed to the bottom of the grove, the tube  160  is situated on the cylindrical surfaces of the rollers  122  ( FIG. 13 ). 
     In a gap formed between the two flat plate parts, the tube stabilizer  230  (a holding part  231 ) according to the embodiment is inserted, and the tube  160  is sandwiched between the tube stabilizer  230  and the flat plate parts  212  and  213 . As a result, the tube  160  is fixed and positioned.  FIG. 16  illustrates an outer appearance of the tube stabilizer  230 .  FIG. 16( a )  is a rear view,  FIG. 16( b )  is a top view,  FIG. 16( c )  is a front view,  FIG. 16( d )  is a side view. The tube stabilizer  230  is a member including the holding part  231  having a shape of a rectangular solid, and a hook  232  protruding from the lower surface of the holding part  231  to the near side, and has such flexibility that the tube stabilizer  230  can cause an engagement/disengagement operation. The tube stabilizer  230  according to the embodiment is formed of resin, such as PET (polyethylene terephthalate) or PP, by the injection molding. On the near side surfaces of the both ends of the holding part  231  in the width direction (the left and right direction in  FIG. 16( b ) ), a pair of recessions  231   a  and  231   b  is formed. On the top surface near the tip of the hook  232 , an engagement nail  233  is formed to protrude upward on the back side. The engagement nail  233  has a shape of a slander triangular prism extending in the width direction, and the tip thereof protruding upward on the back side is formed to have an acute angle. As shown in  FIG. 16( d ) , the vertical cross section of the hook  232  is formed to have a shape of a letter “L”, and a near side surface  232   d  (hereafter, referred to as an “offset surface  232   d ”) of the short length part of the letter “L” is formed to have an offset to the back side with respect to the nearest side surface  231   c  of the holding part  231 . In this embodiment, the offset surface  231  is extended to the holding part  231 , and an offset surface  231   d  continuing from the offset surface  231   c  is formed. The offset surface  231  of the holding part  31  is provided for the purpose of serving to enhance the efficiency of the ejection molding and decreasing the use amount of resin, and the offset surface  231   d  is not necessarily required on the holding part  231 . The opening  234  penetrating through the tube stabilizer  230  in the depth direction is provided for convenience of processing, and the opening  234  is not necessarily required depending on the processing method. 
     When the tube stabilizer  230  is attached to the pump cassette  110 , the holding part  231  is inserted into the space between the flat plate parts  212  and  213 . The thickness of the protruded part of the holding part  231  protruded to the near side from the offset surface  232   d  (the size in the vertical direction in  FIG. 16( d ) ) is set to be substantially equal to the space between the flat plate parts  212  and  213 , and is sandwiched by the flat plate parts  212  and  213  without a gap. The hook  232  of the tube stabilizer  230  is arranged under the flat plate part  212  to be along the flat plate part  212 . The height of the offset surface  232   d  in  FIG. 16( d )  (i.e., the interval between the lower surface of the holding part  231  and the top surface of the hook  232 ) is set to be substantially equal to the thickness of the flat plate part  212 , and the top surface of the hook  232  closely contacts the lower surface of the flat plate part  212 . At a central portion on a lower edge of the front side portion of the pump cassette  110 , an engagement projection  118   a  is formed, and the engagement nail  233  formed at the tip portion of the hook  232  of the tube stabilizer  230  is hooked to the engagement projection  118   a , so that the tube stabilizer  230  is prevented from dropping off the pump cassette  110 . 
     The first end  161  of the tube  160  is sandwiched between the grove  212   a  of the flat plate part  212 , the groove  213   a  of the flat plate part  213  and the recession  231   a  of thee tube stabilizer  230 , and is fixed so as not to move in the longitudinal direction the second end  162  of the tube  160  is sandwiched between the groove  212   b  of the flat plate part  212 , the groove  213   b  of the flat plate part  213  and the recession  231   b  of the tube stabilizer  230 , and is fixed so as not to move in the longitudinal direction. A force for holding the tube  160  between the pump cassette  110  and the tube stabilizer  230  (i.e., a deforming amount of the tube) is determined in accordance with the depth of the grooves  212   a ,  212   b ,  213   a  and  213   b  of the pump cassette  110 , the depth of the recessions  231   a  and  231   b  of the tube stabilizer  230 , and the offset amount of the offset surface  232   d  (the distance between the flat plane including the offset surface  232   d  and the plane including the foreground surface  231   c  of the holding part  231 ). Since these parameters are determined by the processing sizes of the pump cassette  110  and the tube stabilizer  230 , as long as the same tube  160  is used, the tube  160  is held by a predetermined constant force. Therefore, the tube  160  is prevented from being excessively deformed, and the tube  160  is prevented from moving in the longitudinal direction due to an insufficient holding force. Furthermore, by setting the size and the shape of the recessions  231   a  and  231   b  depending on the size and the material (rigidity) of the tube  160 , various types of tubes can be held by an appropriate holding force. Shape variations of the recessions  231   a  and  232   b  are illustrated in  FIGS. 17( a ) to 17( c ) .  FIG. 17( a )  illustrates an example of the tube stabilizer  230  adapted for the tube  160  having a small diameter, and the recessions  231   a  and  231   b  each having a semicircular shape with a small radius which is the same as that of the tube  160  are formed.  FIG. 17( b )  illustrates an example of the tube stabilizer  230  adapted for the relatively rigid tube  160  having a large diameter, and each of the recessions  231   a  and  231   b  is formed such that the depth thereof is small so that the contacting area with the tube becomes small. With this configuration, it is possible to hold the tube with a strong force.  FIG. 17( c )  illustrates an example in which each of the recessions  231   a  and  231   b  is formed to be deep and further the frontage is broadened. With this configuration, the tube  160  can be easily guided to the recessions  231   a  and  231   b  and the grooves  212   a ,  212   b ,  213   a  and  231   b  of the pump cassette  110  when the tube is fixed by the tube stabilizer  230 . 
     The pump cassette  110  accommodates the tube  160  and the rotor  120 , and is fixed to the base  140  in the state where the tube  160  is fixed to the pump cassette  110  by the tube stabilizer  230 . By fixing in advance the tube  160  to the lower edge of the pump cassette  110  by the tube stabilizer  230 , handling of the tube  160  can be eased when the pump cassette  110  is fixed to the caser  140 . 
     When the pump cassette  110  has been fixed to the case  140 , the rotor  120  is sandwiched and held between the pump cassette  110  and the base  140 . Furthermore, the output shaft  30  of the gear box  20  is coupled to the rotor  120 , and the rotational drive by the output shaft  30  becomes available. 
     Next, an attaching and detaching method for the tube stabilizer  230  according to the embodiment is explained. As described above, the tube stabilizer  230  is attached to the pump cassette  110  after the tube  160  and the rotor  120  are accommodated in the pump cassette  110 . When the tube stabilizer  230  is attached, first the first end  161  of the tube  160  is inserted into the groove  212   a  of the flat plate part  212 , the groove  213   a  of the flat plate part  213 , and the second end  162  of the tube  160  is inserted into the groove  212   b  of the flat plate part  212  and the groove  213   b  of the flat plate part  213 . Next, the holding part  231  of the tube stabilizer  230  is inserted into the gap between the flat plate part  231  and the flat plate part  213 . Further, by pressing the lower part of the back surface of the hook  232  toward the near side (in the direction of an arrow A in  FIG. 16( d ) ) (according to circumstances, by further lifting up the tip of the hook  232  while pressing the back surface of the hook  232  to the near side), the engagement nail  233  of the tube stabilizer  230  engages with the engagement projection  118   a  of the pump cassette  110 , and thus the attachment is completed. 
     Next, detaching of the tube stabilizer  230  is explained.  FIG. 18  is an explanatory illustration for explaining the detaching manner of the tube stabilizer  230 . As shown in  FIG. 18 , by pressing down the tip of the hook  232 , the engagement between the engagement nail  233  of the tube stabilizer  230  and the engagement projection  118   a  of the pump cassette  110  is released. By further pressing the tube stabilizer  230  to the back side in this state, the tube stabilizer  230  is detached. As described above, the tube stabilizer  230  according to the embodiment eases the maintenance work for the tube pump  1 , such as replacement of the tube  160 , because the tube stabilizer  230  can be detached through a one touch operation. 
     As described above, in the tube pump  1  according to the embodiment, the pump cartridge providing the pump function is formed by the pump cassette  110 , the tube  160 , the rotor  120  and the tube stabilizer  230 , and the pump cartridge is detachable attachable to the drive part (the drive motor  10 , the gear box  20  and the base  140 ). Furthermore, the tube  160  is fixed to the pump cartridge by the tube stabilizer  230 . In such a configuration, since each of the ends  161  and  162  of the tube is positioned and fixed to the pump cassette  110 , the need for the work for adjusting the position of the tube  160  is eliminated when the pump cartridge is attached to the drive part, and therefore the assembling and maintenance work for the tube pump  1  may be made more efficient. However, the configuration of the embodiment is not limited to such examples, a pump cartridge may be configured not to be detachable attachable to the drive part, and the tube may be fixed to the drive part (e.g., the base  140 ) by the tube stabilizer  230 . 
     The forging is exemplary embodiments of the present invention. However, embodiments are not limited to the foregoing, and can be varied within the scope of the technical concept described in the claims. Hereafter, some variations of the embodiments according to the invention are shown. In the following variations, to elements which are the same as or correspond to those of the above described embodiments, the same or similar reference symbols are assigned. 
     In the above described embodiments, the tube  160  is held by sandwiching the tube  160  between the flat plate parts  212  and  213  (specifically the groves  212   a ,  212   b ,  213   a  and  213   b ) of the pump cassette  110  and the recessions  231   a  and  231   b  of the tube stabilizer  230 . In this configuration, since the flat plate parts  212  and  213  and the holding part  231  are not on the same plane, a shearing force is applied to the tube. For this reason, when the thin-walled tube made of soft resin is used, the tube may buckle. In such a case, a second holding part  235  which is arranged between the flat plate part  212  and  213  to face the holding part  231  and which holds the tube  160  between the second holding part  235  and the holding part  231  may be provided. 
       FIG. 19  illustrates an example of the tube stabilizer  230  having the second holding part  235 .  FIG. 19  is a bottom view defined by cutting the pump cassette  110  to which the tube stabilizer  230  is attached by the top surface of the flat plate part  212 . The second holding part  235  is arranged on the near side of the gap formed between the flat plate part  212  and the flat plate part  213  (the upper side in  FIG. 19 ). Specifically, the second holding part  235  is used in the state where the second holding part  235  is sandwiched between the holding part  231  and the near side portion of a lower side wall  118  which connects the flat plate part  212  to the flat plate part  213 . Recessions  235   a  and  235   b  are formed at the back side portion (the lower side in  FIG. 19 ) of the second holding part  235 . The shape and size of each of the recessions  235   a  and  235   b  is set appropriately in accordance with the material and the size of the used tube  160 . In the example shown in  FIG. 19 , each of the recessions  235   a  and  235   b  is formed to be a semicircular shape having a diameter slightly smaller than the used tube. The first end  161  (not shown) of the tube  160  is held while being sandwiched between the recession  231   a  a of the holding part  231  and the recession  235   a  of the second holding part  235 . The second end  162  of the tube  160  is held while being sandwiched between the recession  231   b  of the holding part  231  and the recession  235   b  of the second holding part  235 . 
     In the example shown in  FIG. 19 , the end surface on the back side of the second holding part  235  is formed to be a flat shape, and is formed to contact the end surface on the near side of the holding part  231 . Therefore, the force for holding the tube  160  (the deforming amount of the tube  160 ) is determined in accordance with the shapes and the sizes of the recessions  231   a  and  231   b  of the holding part  231  and the recessions  235   a  and  235   b  of the second holding part  235 . In another example, the near side end surface of the holding part  231  may not contact the end surface of the second holding part  235 , and in this case a constant holding force determined in accordance with the size of the tube stabilizer  230  is applied to the tube  160 . Therefore, as long as the material and the size of the tube  160  are not changed, it is possible to constantly apply a predetermined holding force to the tube  160  even if the tube stabilizer  230  is attached or detached. 
     In the example shown in  FIG. 19 , the positions of the tips of the recessions  235   a  and  235   b  of the second holding part  235  are situated on the back side with respect to the positions of the tips of the grooves  213   a  and  213   b  of the flat plate part  213  as indicated by a dashed line. The width and depth of the grooves  213   a  and  213   b  of the flat plate part  213   n  are formed to be large enough so that various types of tubes can be used. Therefore, regarding the positioning method in which the tube  160  is pushed to contact the tips of the grooves  213   a  and  213   b  in the above described embodiments, the tube cannot be necessarily positioned at the optimum position. By providing the second holding part  235 , a more appropriate positioning can be realized in accordance with the thickness and the material of the tube. 
     Although, in the example shown in  FIG. 19 , the second holding member  235  is formed of one piece, the part for holding the first end  161  of the tube  160  (the part where the recession  235   a  is formed) and the part for holding the second end  162  of the tube  160  (the part where the recession  235   b  is formed) may be separate members. Although, in the example shown in  FIG. 19 , the near side end of the second holding part  235  is formed to be along the lower side wall  118  of the pump cassette  110 , the shape of the near side end of the second holding part  235  is not limited to the shape shown in  FIG. 19  as long as the second holding part  235  can be securely and stably positioned at an appropriate position. Although, in the example shown in  FIG. 19 , the holding part  231  and the second holding member  235  are provided as separate members, the holding part  231  and the second holding part  235  may be formed as an integrated member. For example, as shown in  FIG. 20 , the tube stabilizer  230  may be formed such that the first holding part  231  and the second holding part  235  are coupled via a joint part  236 . In this case, the joint part  236  serves as a kind of hinge, and it is possible to attach the tube stabilizer  230  to the tube  160  while causing the first holding part  231  and the second holding part  235  to depart from each other around the joint part  236  serving as an axis. 
     In the above described embodiments, one engagement nail  233  of the tube stabilizer  230  and one engagement projection  118   a  of the pump cassette  110  are formed, respectively. However, the number, the position and the shape of each of the engagement nails  233  and the engagement projections  118   a  are not limited to those in the above described embodiments. A plurality of engagement nails and engagement projections  118   a  may be provided depending on the material, the size and the arrangement interval of the tube. The number of the engagement nail  233  and the engagement projection  118   a  may not be one-to-one relationship. For example, a plurality of short engagement nails  233  may engage with one long engagement projection  118   a.    
     The tube pump  1  according to the above described embodiment is a rotational pump configured such that the liquid in the tube is transported, by arranging the tube along the cylindrical inner surface of the pump cassette, by moving the rollers to cause the orbital motion along the inner surface and thereby continuously pressing and flattening the tube. However, embodiments of the invention are not limited to such a configuration. For example, the tube pump may be a linear type pump in which a tube is arranged on a slender flat plate and a roller moves straight along the flat plate. 
     In the tube pump  1  according to the above described embodiment, the two parallel flat plate parts  212  and  213  are formed, and the holding part  231  of the tube stabilizer  230  is inserted into the space between the two flat plate parts  212  and  213 . However, embodiments of the invention are not limited to such a configuration. For example, when the second holding part  235  is not used, the tube  160  can be fixed by only one of the flat plate parts sandwiched between the holding part  231  and the hook  232 . In place of the flat plate parts, a rail or a projection for supporting the ends (e.g., both ends in the width direction) of the tube stabilizer  230  may be provided on the inner surface of the lower side wall  118 . 
     As described above, by using the tube fixing member according to the embodiment of the invention, pulling-in of the flexible tube due to the movement of the roller can be effectively prevented.