Abstract:
A flange attaching section has a flange supporting section and a movable section, and the movable section can approach the flange supporting section and separate therefrom due to rotational moving. Even if a flange section of a barrel of a syringe has various thickness, the flange section is easily attached between the flange supporting section and the movable section, and although the attachment is easy, the flange section comes in pressure contact with the flange supporting section in the attached state. Even if, therefore, the flange section of the barrel of the syringe has various thickness, a syringe pump, in which moving of the barrel of the syringe during infusion is prevented securely and the infusion is executed at an accurate speed, is provided.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a syringe pump for injecting various drug solution, blood, or the like to human bodies using a syringe. 
   2. Description of the Related Art 
     FIG. 1  shows a first related art of the syringe pump (JP, B2, 63-44389). The syringe pump  11  of the first related art includes an operation/display section  13  which is an upper surface portion of a case  12 , and a syringe attaching section  14 . The operation/display section  13  has various operation buttons and display sections, and the syringe attaching section  14  has a flange attaching section  15 , a barrel attaching section  16 , a slider  17  and a syringe diameter detecting section  18 . The barrel attaching section  16  has a pair of projected ribs  21  which form a groove shaped section. 
   The flange attaching section  15  has end surfaces  21   a  of the pair of projected ribs  21  on a side of the slider  17 , a pair of projected portions  22  opposed to the end surfaces  21   a , and slits  23  between the end surfaces  21   a  and the projected portions  22 . In order to use the syringe pump  11 , the syringe  24  which is loaded with drug solution or the like is attached to the syringe attaching section  14 . At the time of the attachment, a barrel  25  of the syringe  24  is attached to the barrel attaching section  16  and the syringe diameter detecting section  18 , a flange section  26  of the barrel  25  is inserted into the slits  23 , and a flange section  28  of a plunger  27  is attached to the slider  17 . 
   The syringes  24  are manufactured by a plurality of manufacturers, and one manufacturer manufactures the syringes  24  of plural types. Dimensions of the respective sections of the syringe  24  differ according to manufacturers and types of the syringes  24 , and a thickness of the flange section  26  of the barrel  25  also differs according to manufacturers and types of the syringes  24 . Meanwhile, the syringe pump  11  is designed so as to be capable of being used for the syringes  24  of all manufacturers and all the types. A width of the slits  23  is, therefore, determined so that the most thick flange section  26  in the syringes  24  of various manufacturers and types can be inserted thereinto. 
   A diameter of the barrel  25  also differs according to manufacturers and types of the syringes  24 . Since the syringe diameter detecting section  18 , however, detects the diameter of the barrel  25 , a sliding speed of the slider  17  for obtaining a desired infusion speed is determined based on the detected diameter. The slider  17  slides to a direction approaching the flange attaching section  15  at the determined sliding speed so as to press the flange section  28  of the plunger  27 , and the plunger  27  is gradually inserted into the barrel  25 . As a result, the infusion is executed always at the desired infusion speed regardless of the diameter of the barrel  25 . 
   When the slider  17  slides to a position corresponding to a state where a tip of the plunger  27  is separated from the end surfaces  21   a  by a predetermined distance, a “warning that shows predetermined time before end of infusion” is given. When the slider  17  further slides to a position corresponding to a state where the tip of the plunger  27  is separated from the end surfaces  21   a  by a distance for reaching an injection end of the barrel  25 , an “infusion end warning” is given. That is to say, an infusion quantity is calculated at the time of the infusion on the premise that the flange section  26  comes in pressure contact with the end surfaces  21   a.    
   In a second related art of the syringe pump, an elastic supporting piece which elastically presses the flange section  26  of the barrel  25  of the syringe  24  against the end surfaces  21   a  is provided between the projected portions  22  in the syringe pump  11  of the first related art (JP, B2, 6-36827). 
   In the syringe pump  11  of the first related art, however, the width of the slits  23  is determined so that the flange section  26  which has the largest thickness in the syringes  24  of various manufacturers and types can be inserted thereinto. When the flange section  26  is inserted into the slits  23 , therefore, a gap is normally generated between the slits  23  and the flange section  26 . 
   When the slider  17  presses the plunger  27 , the barrel  25  also moves to an opposite direction from the slider  17  in result until the flange section  26  comes in pressure contact with the end surfaces  21   a . While the barrel  25  is moving, the infusion is not executed at all, or the infusion speed is lowered. Even if the moving distance of the barrel  25  is slight, when a slight quantity of highly medicable drug solution is infused or the like, the moving of the barrel  25  cannot be ignored. 
   On the contrary, in the syringe pump of the second related art, since the elastic supporting piece, which elastically presses the flange section  26  of the barrel  25  of the syringe  24  against the end surfaces  21   a , is provided, when the flange section  26  is fitted between the elastic supporting piece and the end surfaces  21   a , the flange section  26  comes in pressure contact with the end surfaces  21   a . When the slider  17  presses the plunger  27 , the barrel  25  does not move to the opposite direction from the slider  17 . 
   In a state, however, in which the syringe  24  is attached to the syringe pump, since the plunger  27  of the syringe  24  is positioned above the elastic supporting piece, the elastic supporting piece should be necessarily shortened. Since the thin elastic supporting piece is easily damaged, the elastic supporting piece should be necessarily thicken, and in result it has strong elastic force. When the elastic supporting piece is short and has the strong elastic force, strong force should be applied to the elastic supporting piece in order to elastically deform it. In a state where the elastic supporting piece is not elastically deformed, the gap between the elastic supporting piece and the end surfaces  21   a  is extremely narrow. 
   The flange section  26  is, therefore, difficultly fitted between the elastic supporting piece and the end surfaces  21   a , and even if the flange section  26  is not fitted therebetween, the flange section  26  is easily taken to be fitted by an operator. In the end, also in the syringe pump of the second related art, the barrel  25  frequently moves to the opposite direction from the slider  17  due to the pressing of the plunger  27  by the slider  17  until the flange section  26  comes in pressure contact with the end surfaces  21   a.    
   In any one of the syringe pumps  11  of the first and second related arts, at the time of attaching the syringe  24 , even if the flange section  26  of the barrel  25  is not attached into the slits  23  which is the proper position but is attached to an improper position, for example, a position which is closer to the slider  17  than the projected portions  22  as shown by a chain line in  FIG. 1 , the attachment to the improper position is not detected at all. When the flange section  26  of the barrel  25  is attached to the position which is closer to the slider  17  than the projected portions  22  as shown by the chain line in  FIG. 1 , the flange section  28  of the plunger  27  is separated from the end surfaces  21   a  excessively in comparison with the case where the flange section  26  is attached into the slits  23 . 
   When the flange section  28  of the plunger  27  is attached to the slider  17 , it is necessary to excessively separate also the slider  17  from the end surfaces  21   a . The syringe pump  11  judges to necessarily infuse a larger quantity of the drug solution than the quantity of the drug solution with which the syringe  24  is actually loaded, namely, judges to necessarily slide the slider  17  over a longer distance than the proper distance, and starts the infusion. As a result, before the “infusion end warning” is given, or in some cases even before the “warning that shows predetermined time before end of infusion” is given, the tip of the plunger  27  reaches the injection end of the barrel  25 . 
   Meanwhile, the tip portion of the plunger  27  has a flexible sealing member made of rubber or the like in order to seal the solution. When the pressing of the plunger  27  by the slider  17  is continued also after the tip of the plunger  27  reaches the injection end of the barrel  25 , the sealing member on the tip of the plunger  27  is compressed so as to be deformed. That is to say, while the sealing member is being compressed and is deformed, the plunger  27  is continued to be pressed by the slider  17 . Since, however, the compressive deformation of the sealing member is limited, when the plunger  27  cannot be moved despite the pressing of the plunger  27  by the slider  17 , the syringe pump  11  judges that the syringe  24  is blocked, so that “blocking warning” is given. 
   During time when the tip of the plunger  27  reaches the injection end of the barrel  25  and then the “blocking warning” is given, however, the infusion is actually not executed at all. Even if, therefore, the syringe  24  is replaced immediately upon the “blocking warning”, the infusion is regarded to be interrupted. When the infusion is interrupted while the solution is being infused in order to inject a slight quantity of vasopressor, hypotensor or the like, the interruption of the infusion is serious such that this determines life and death of a patient. Even when the interruption of the infusion is not so serious, the operator gets confused in the following case. The case is such that the infusion is actually completed before the “warning that shows predetermined time before end of infusion” or the “infusion end warning” is given, and that althougt the syringe  24  is not actually blocked, the “blocking warning” is given. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a syringe pump in which even if a flange section of a barrel of a syringe has various thickness, moving of the barrel of the syringe during infusion is prevented securely and the infusion is executed at an accurate speed, and when the flange section of the barrel of the syringe is not attached to a flange attaching section, this can be detected, and a quantity of solution is calculated accurately at the time of the infusion so that warning, display or the like is executed accurately. 
   In a syringe pump according to a first invention, a flange attaching section has a flange supporting section and a movable section, and the movable section can approach the flange supporting section and separate therefrom due to rotational moving. In the separation by the rotational moving, a gap between the flange supporting section and the movable section can be larger in comparison with separation by elastic deformation, for example. Even if the gap between the flange supporting section and the movable section is large in a state where the movable section is separated from the flange supporting section, at the time of approaching by the rotational moving, the gap between the flange supporting section and the movable section can be smaller in comparison with approaching by elastic deformation, for example. 
   Even if, therefore, the flange section of the barrel of the syringe has various thickness, the flange section is easily attached between the flange supporting section and the movable section. Although the attachment is easy, the flange section comes in pressure contact with the flange supporting section in the attached state. The moving of the barrel of the syringe during infusion is, therefore, prevented securely, the infusion is executed at an accurate speed. Further, a flange attaching operation section which rotationally moves the movable section of the flange attaching section is further provided separately from the flange attaching section. For this reason, even in such a case that an insufficient space is provided around the flange attaching section and thus an operator cannot easily and directly move the movable section rotationally, the flange section can be easily attached between the flange supporting section and the movable section. 
   In a preferred syringe pump according to the first invention, since barrel attaching section has not only a barrel supporting section but also a barrel pressing section, the moving of the barrel of the syringe during the infusion is prevented with high reliability. Since the flange attaching operation section serves also as the barrel pressing section, the moving of the barrel of the syringe during the infusion is prevented by a small number of operations, and omission of the operations for the prevention is less. Even if the flange section of the barrel of the syringe has various thickness, the infusion is executed at a more accurate speed and easily and securely. 
   In a syringe pump according to a second invention, after the movable section of the flange attaching section finishes approaching the flange supporting section, the barrel pressing section presses the barrel of the syringe against the barrel supporting section. The barrel is prevented from being pressed against the barrel supporting section in the state that the flange section does not come in pressure contact with the flange supporting section yet, the moving of the barrel of the syringe during the infusion is prevented with higher reliability. Even if, therefore, the flange section of the barrel of the syringe has various thickness, the infusion is executed at a more accurate speed. 
   In a syringe pump according to a third invention, a detecting section detects whether the flange section of the barrel of the syringe is attached to the flange attaching section or not. That is to say, when the flange section of the barrel of the syringe is not attached to the flange attaching section, the detecting section can detect this. For this reason, the operator can reattach the flange section to the flange attaching section immediately based on the detection by the detecting section. At the time of the infusion, therefore, an infusion quantity is calculated accurately, and warning, displaying, or the like is executed accurately. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view that shows a first related art of the present invention in a state where a syringe is attached; 
       FIG. 2  is a sectional view that shows a main section in the first embodiment of the present invention in a state where the syringe is attached properly; 
       FIG. 3  is a plan view that shows the first embodiment of the present invention in the state where the syringe is attached properly; 
       FIG. 4  is a sectional view that shows the main section in the first embodiment of the present invention in a state where the syringe is attached improperly; 
       FIG. 5  is a sectional view that shows the main section in the first embodiment of the present invention in a preparation state for attaching the syringe; 
       FIG. 6  is a sectional view that shows the main section in the first embodiment of the present invention in a state where the syringe is not attached; 
       FIG. 7  is a side view that viewed from a position of line VII—VII in  FIG. 9 ; 
       FIG. 8  is a sectional view that viewed from a position of line VIII—VIII in  FIG. 9 ; and 
       FIG. 9  is a plan view that shows the first embodiment of the present invention in the state where the syringe is not attached. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The first embodiment of the present invention will be explained below with reference to  FIGS. 2 through 9 .  FIGS. 6 through 9  show a syringe pump of the embodiment in a state where a syringe is not attached. The syringe pump  31  of the embodiment is provided with an operation/display section  33  which is an upper surface of a case  32 , a handle section  34  and a syringe attaching section  35 . The operation/display section  33  is provided with various operation buttons and display sections. The syringe attaching section  35  is provided with a flange attaching section  36 , a barrel attaching section  37 , a slider  38  and a syringe diameter detecting section  41 . 
   A projected rib  42  which extends along a portion of the operation/display section  33  is provided on the barrel attaching section  37 , and a groove  43  having a V-shaped section is provided between the operation/display section  33  and the projected rib  42 . An end surface of the projected rib  42  on a side of the slider  38  is opposed to a projected portion  44  having a sectional shape similar to the projected rib  42 , and a flange pressing plate  46  is opposed to an end surface  45  on a side of the slider  38  formed by the projected rib  42  and the operation/display section  33 . The end surface  45 , the flange pressing plate  46  and the like compose the flange attaching section  36 . The flange pressing plate  46  has a section of V shape similar to the groove  43 , and is mounted rotatively to the case  32  by a pair of pins  47   a  and  47   b.    
   A flange pressing block  48  is mounted in the case  32  so as to be movable in an extending direction of the groove  43 , and a groove  48   a  is provided on an end of the flange pressing block  48  on the side of the slider  38 . A portion of the pin  47   a  which is projected from the flange pressing plate  46  is bent into an L shape, and its tip end is arranged in the groove  48   a . A helical compression spring  51  is mounted to an end of the flange pressing block  48  opposite to the groove  48   a , and the helical compression spring  51  applies energy to the flange pressing block  48  towards the groove  48   a.    
   The groove  48   a  approaches the slider  38  by means of the moving of the flange pressing block  48  due to the applied energy. Since the tip of the pin  47   a  is arranged in the groove  48   a , when the groove  48   a  approaches the slider  38 , the pins  47   a  and  47   b  and the flange pressing plate  46  move rotationally, so that the tip of the flange pressing plate  46  comes in pressure contact with the end surface  45 . 
   A cylinder section  52  whose outer peripheral surface is a plane within a predetermined angle range is provided between the projected rib  42  and the projected portion  44 , and a knob  53 , which has a cylindrical shape with an inner peripheral surface matching with the outer peripheral surface of the cylindrical section  52  and has a hook-shaped tip, wraps the cylindrical section  52 . A cylindrical section  54  which is coaxially with the cylindrical section  52  is provided in the case  32 , and the cylindrical section  54  is provided with a slit which extends to an axial direction. A pillar section  55  which is longer than the knob  53  is mounted to the knob  53  coaxially with the knob  53 , and the pillar section  55  is projected into the case  32  via the cylindrical sections  52  and  54 . 
   A cylindrical section  56 , which has a rack  56   a  on an outer peripheral surface in the axial direction wraps the pillar section  55 , and the rack  56   a  is inserted into the slit of the cylindrical section  54  in the axial direction. The cylindrical section  56  is prevented from dropping off from the pillar section  55  by an E ring  57  at the tip of the pillar section  55 . A helical compression spring  58  wraps the pillar section  55  in the cylindrical sections  52  and  54 , and the helical compression spring  58  applies energy to the cylindrical section  56 , the pillar section  55  and the knob  53  in a direction from the outside to the inside of the case  32 . In the states in  FIGS. 6 through 9 , a lower end surface of the knob  53  comes in pressure contact with an outer surface of the case  32 . 
   A link fixture  61  is fitted into the outer peripheral surface of the cylinder section  56 , and one end of a link  62  is mounted to the link fixture  61 . The other end of the link  62  is mounted to the end of the flange pressing block  48  opposite to the groove  48   a , and a plate section  48   b  extends from the end opposite to the groove  48   a  to a direction along the cylindrical section  54 . A light emitting element  63  and a light receiving element are arranged on both sides of a tip of the plate section  48   b . A potentiometer  64  is attached to a vicinity of the cylindrical section  54 , and a gear of the potentiometer  64  is engaged with the rack  56   a . The potentiometer  64 , the rack  56   a , the knob  53 , and the like compose the syringe diameter detecting section  41 . 
   The slider  38  is connected with a driving shaft  65  for sliding the slider  38 , and a guide shaft  66  for guiding the slider  38  at the time of the sliding. The driving shaft  65  is connected with a driving mechanism in the case  32 . The slider  38  includes a pair of holding sections  67  for holding the plunger of the syringe therebetween, a detecting section  68  for detecting the flange section of the plunger of the syringe, and an operation button  71  for operating the slider  38 . When the operation button  71  is pressed, the holding sections  67  are separated from each other so as to be brought into a state where they can hold the plunger of the syringe therebetween, and the slider  38  is brought into a slidable state manually. 
   In order to use the above syringe pump  31 , the knob  53  is moved on the outer peripheral surface of the cylindrical section  52  to a direction where it is separated from the outer surface of the case  32  against the applied energy of the helical compression spring  58 . According to the moving, the pillar section  55  moves in the cylindrical sections  52  and  54  to a direction from the inside to the outside of the case  32 . When the pillar section  55  is moved, the E ring  57  also moves simultaneously, and thus the cylindrical section  56  is also pushed by the E ring  57  so as to move in the cylindrical section  54  to the direction from the inside to the outside of the case  32 . 
   At this time, the link fixture  61  receives the applied energy from the helical compression spring  51  via the link  62 , and the applied energy of the helical compression spring  51  received via the link  62  includes a component directing from the outside to the inside of the case  32 . The link fixture  61  slides with respect to the cylindrical section  56  due to the component, and does not approach the cylindrical section  54  until the E ring  57  touches the link fixture  61 . When the knob  53  is further separated from the outer surface of the case  32  and the E ring  57  touches the link fixture  61 , as shown in  FIG. 5 , the link fixture  61  is also pushed by the E ring  57  so as to move together with the cylindrical section  56  until it touches the cylindrical section  54 . 
   When the link fixture  61  is pushed by the E ring  57 , the flange pressing block  48  receives force from the link fixture  61  via the link  62 . This force includes a component directing from the groove  48   a  of the flange pressing block  48  to the helical compression spring  51 . Due to this component, the flange pressing block  48  is moved to a direction from the groove  48   a  to the helical compression spring  51  against the applied energy of the helical compression spring  51 . Due to the moving of the flange pressing block  48 , the pins  47   a  and  47   b  and the flange pressing plate  46  moves rotationally to a direction where the tip of the flange pressing plate  46  is separated from the end surface  45 , so that a gap is formed between the end surface  45  and the flange pressing plate  46 . 
   When the link fixture  61  touches the cylindrical section  54 , the knob  53  can not be further separated from the outer surface of the case  32 . In this state, a lower end surface of the knob  53  is slightly higher than an upper end surface of the cylindrical section  52 , and the knob  53  and the pillar section  55  can be rotated with respect to the cylindrical section  52 . As described above, the outer peripheral surface of the cylindrical section  52  is the plane within a predetermined angle range, and an inner peripheral surface of the knob  53  coincides with the outer peripheral surface of the cylindrical section  52 . Therefore, when the knob  53  and the pillar section  55  are rotated with respect to the cylindrical section  52 , a section of the knob  53  does not correspond to the section of the cylindrical section  52 . 
   Even if the force which separates the knob  53  from the outer surface of the case  32  against the applied energy of the helical compression spring  58  is released, in result, the knob  53  does not approach the outer surface of the case  32  in a state where it is positioned on the cylindrical section  52 . In this state, therefore, as shown in  FIGS. 2 and 3 , a syringe  72  loaded with drug solution or the like is attached to the syringe attaching section  35 . At the time of the attachment, a barrel  73  of the syringe  72  is attached to the barrel attaching section  37 , and a flange section  74  of the barrel  73  is inserted into the gap formed between the end surface  45  and the flange pressing plate  46  in the state of  FIG. 5 . A width of the gap is determined so that even the flange section  74  with the largest thickness in the syringes  27  of various manufacturers and types can be inserted. 
   In a state where the operation button  71  is pressed and the holding sections  67  are separated from each other, a plunger  75  is slid manually to a position where the plunger  75  can be held between the holding sections  67 . In this position, the pressing of the operation button  71  is released and the holding sections  67  approach each other so that the plunger  75  is held between the holding sections  67 . The knob  53  and the pillar section  55  are, thereafter, rotated with respect to the cylindrical section  52  to a direction opposite to the rotation for obtaining the state in  FIG. 5  until the section of the knob  53  corresponds to the section of the cylindrical section  52 . 
   The knob  53 , in result, moves on the outer peripheral surface of the cylindrical section  52  to a direction where the knob  53  approaches the outer surface of the case  32  due to the applied energy of the helical compression spring  58 . According to the moving, the pillar section  55  moves in the cylindrical sections  52  and  54  to a direction from the outside to the inside of the case  32 . When the pillar section  55  moves, the E ring  57  also moves simultaneously, and thus the cylindrical section  56  also moves in the cylindrical section  54  to the direction from the outside to the inside of the case  32  due to the applied energy of the helical compression spring  58 . 
   When the E ring  57  moves simultaneously with the pillar section  55 , the force, which is applied from the E ring  57  via the link fixture  61  and the link  62  to the flange pressing block  48 , is released. As a result, the flange pressing block  48  moves towards the groove  48   a  by the applied energy of the helical compression spring  51 , and the groove  48   a  approaches the slider  38 . The pins  47   a  and  47   b  and the flange pressing plate  46 , therefore, move rotationally to the direction where the flange pressing plate  46  approaches the end surface  45 . The flange pressing plate  46  presses the flange section  74  and the flange section  74  comes in pressure contact with the end surface  45 . 
   The link fixture  61  also moves together with the cylindrical section  56  by the applied energy from the helical compression spring  51  via the link  62  so as to be separated from the cylindrical section  54 . When the flange section  74  comes in pressure contact with the end surface  45 , the flange pressing block  48  and the link fixture  61  do not move any more. Also after the flange section  74  comes in pressure contact with the end surface  45 , the knob  53  approaches the outer surface of the case  32 . The knob  53 , however, presses the barrel  73  of the syringe  72 , and when the barrel  73  comes in pressure contact with the inner surface of the groove  43 , the knob  53  does not move any more. 
   As sown in  FIG. 2 , when the flange pressing plate  46  presses the flange section  74  and the flange section  74  comes in pressure contact with the end surface  45 , even if the thickness of the flange section  74  is the smallest in the syringes  72  of various manufacturers and types, the tip of the plate section  48   b  of the flange pressing block  48  is positioned between the light emitting element  63  and the light receiving element. The light receiving element cannot, therefore, receive light from the light emitting element  63 , and in result a detection is made that the flange section  74  is attached properly to the flange attaching section  36 . In this detecting state, the infusion can be started normally. 
   When the flange section  74  comes in pressure contact with the end surface  45 , even if the flange section  74  has various thickness, the moving of the barrel  73  due to the the pressing of the flange section  76  of the plunger  75  by the slider  38  during the infusion can be prevented. The infusion is, therefore, executed at an accurate speed. 
   Meanwhile, when the syringe  72  is not attached to the syringe pump  31  at all as shown in  FIG. 6 , or the barrel  73  of the syringe  72  is attached to the barrel attaching section  37  but the flange section  74  is not attached to the flange attaching section  36  as shown in  FIG. 4 , the tip of the plate section  48   b  is not in a position where the light receiving element can be inhibited from receiving the light from the light emitting element  63 . The detection is made by the light receiving that the flange section  74  is not attached to the flange attaching section  36 . In this detecting state, if the infusion is tried to be started, the operation/display section  33  warns and displays this, and thus the infusion cannot be started. 
   Also in the case where the plunger  75  of the syringe  72  is not held between the holding sections  67  as shown in  FIG. 4 , this is detected by the detecting section  68 . The operation/display section  33  warns and displays this, and thus the infusion cannot be started. An operator can, therefore, reattach the syringe  72  to the syringe attaching section  35  and the slider  38  based on the warning and the displaying. 
   When the syringe  72  is attached to the syringe attaching section  35  properly, the knob  53  is still in a state where it presses the barrel  73 , and the engaged position between the gear of the potentiometer  64  and the rack  56   a  corresponds to a diameter of the barrel  73 . The diameter of the barrel  73  is, therefore, obtained from an output of the potentiometer  64 . When the diameter has a nonstandard value, the operation/display section  33  warns and displays this, and thus the infusion cannot be started. When the diameter of the barrel  73  has a standard value, a sliding speed of the slider  38  for obtaining a desired infusion speed is determined from the diameter. 
   In order to detach the syringe  72  from the syringe attaching section  35  when the infusion is ended and the syringe  72  is tried to be replaced by new one during the infusion, the knob  53  is changed from the state of  FIG. 2  into the state of  FIG. 5  in a similar manner to that when the knob  53  is changed from the state of  FIG. 6  into the state of  FIG. 5  so that the syringe  72  is attached. In this case, after the knob  53  releases the pressing against the barrel  73 , the flange pressing plate  46  moves rotationally to the direction where it is separated from the end surface  45 . As is clear from the above explanation, the knob  53  serves also as an operating unit for making the flange pressing plate  46  approximate to the end surface  45  and separating them, and a pressing unit for pressing the barrel  73 . 
   The knob  53  does not necessarily serve also as the operating unit and the pressing unit, and the operating unit for making the flange pressing plate  46  approximate to the end surface  45  and separating them may be provided separately from the knob  53 . The force, which moves rotationally the pins  47   a  and  47   b  and the flange pressing plate  46  to the direction where the flange pressing plate  46  approaches the end surface  45 , is obtained by the helical compression spring  51 , but the force may be obtained by another unit such as an eccentric cam.