Patent Publication Number: US-2016242802-A1

Title: Fluid injection device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/472,821, filed Aug. 29, 2014, which is a Continuation of U.S. patent application Ser. No. 13/039,042 filed on Mar. 2, 2011, now U.S. Pat. No. 8,857,734 which claims priority to Japanese Patent Application No. 2010-046299, filed on Mar. 3, 2010, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a fluid injection device including an injection pipe and a suction pipe. 
     2. Related Art 
     A method for excising, incising, and crushing a living tissue by using a fluid injection device has preferable characteristics as a surgical instrument such as capabilities of preventing heat damage and preserving blood vessels and other capillary tissues. When an operation is performed using the fluid injection device, injected liquid, excised tissues or the like which remains on the portion of surgery becomes an obstacle for securing vision in some cases. As a technology for overcoming this problem, such a fluid injection device further including a suction pipe capable of removing liquid or excised tissues by suction is known. 
     As an example of this type of fluid injection device, a device which has an injection pipe for injecting high-pressure fluid as a pipe disposed within a suction channel of a suction pipe in such a position as to be concentric with the suction channel has been proposed (see JP-A-1-313047). 
     Another example of the fluid injection device currently proposed includes an injection pipe for injecting high-pressure fluid as a pipe inserted eccentrically with respect to the inner circumferential surface of a suction pipe (see JP-A-6-90957). 
     A further example of the fluid injection device sharply changes the volume of a fluid chamber by using a volume varying unit to convert fluid into pulse flow and inject the pulse flow through an injection opening as pulses at high speed (see JP-A-2008-82202). 
     According to the technology disclosed in JP-A-1-313047, the inner circumferential surface of the suction pipe and the outer circumferential surface of the injection pipe are concentrically disposed. Thus, the size of the suction channel at a suction opening (the length of the clearance between the inner circumferential surface of the suction pipe and the outer circumferential surface of the injection pipe) becomes half of the difference between the inside diameter of the suction pipe and the outside diameter of the injection pipe. In this case, it is difficult to remote excised tissues larger than the size of the suction channel at the suction opening by suction. When the diameter of the suction pipe is increased to secure the sufficient size of the suction channel, the vision for surgery is narrowed. 
     According to the technology disclosed in JP-A-6-90957, the injection pipe is inserted eccentrically to the inner circumferential surface of the suction pipe. In this case, the size of the suction channel corresponds to the difference between the inside diameter of the suction pipe and the outside diameter of the injection pipe, and thus becomes larger than the size of the suction channel in the concentric structure shown in JP-A-1-313047 when the suction pipe and the injection pipe have the same diameters as those in the concentric structure. However, there is a possibility that vibration is generated at the top end of the injection pipe, that is, in the vicinity of the injection opening at the time of injection of high-pressure fluid. In this case, injection of fluid toward the target surgery portion becomes difficult. 
     Moreover, according to the structure which inserts the injection pipe eccentrically to the suction pipe as the structure shown in JP-A-6-90957, the position of the injection opening cannot be directly recognized by visual check. Thus, injection of fluid to the accurate position of the target surgery portion is difficult. 
     According to the fluid injection device disclosed in JP-A-2008-82202, excision can be achieved by using a smaller amount of fluid than the amount of high-pressure fluid injected as continuous streams used by the methods shown in JP-A-1-313047 and in JP-A-6-90957. In case of the structure disclosed in JP-A-2008-82202, however, there is a case in which a suction pipe is required for improvement of visual recognizability of the surgery portion or for removal of excised tissues by suction. In this case, the injection pipe can be inserted eccentrically to the inner circumferential surface of the suction pipe for increasing the size of the suction channel as in the structure shown in JP-A-6-90957. However, when fluid is injected as pulses in this structure, it is expected that vibration of the injection pipe becomes larger than vibration generated by continuous flow injection. 
     When vibration is generated on the injection pipe, abnormal noise is produced by contact between the injection pipe and the suction pipe. Moreover, when the suction pipe is resonated by vibration generated at the top end of the injection pipe (injection opening), injection of fluid toward the surgery portion becomes difficult. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a technology capable of solving at least a part of the problems described above and the invention can be implemented as the following forms or application examples. 
     Application Example 1 
     This application example of the invention is directed to a fluid injection device which includes: a pulse generator which converts fluid into pulse flow; a suction pipe projecting from the pulse generator; an injection pipe which is eccentrically inserted into the suction pipe such that the outer circumferential surface of the injection pipe contacts the inner circumferential surface of the suction pipe, and has an injection opening communicating with the pulse generator; and a suction channel and a suction opening formed between the inner circumferential surface of the suction pipe and the outer circumferential surface of the injection pipe. In this case, the injection pipe is fixed to the inner circumferential surface of the suction pipe in the vicinity of the injection opening. 
     According to this application example, the injection pipe is eccentrically inserted into the suction pipe. In this case, the size of the suction channel corresponds to the difference between the inside diameter of the suction pipe and the outside diameter of the injection pipe. When the inside diameter of the suction pipe and the outside diameter of the injection pipe are d 1  and d 2 , respectively, the size of the suction channel (length of clearance) is expressed as d 1 −d 2 . On the other hand, according to a structure which concentrically disposes the suction pipe and the injection pipe, the size of the suction channel corresponds to (d 1 −d 2 )/2. In this case, the size of the suction channel in the eccentric structure becomes larger than the size of the suction channel in the concentric structure. Thus, larger excised tissues can be sucked in the structure in which the injection pipe and the suction pipe are eccentrically disposed than in the structure in which the injection pipe and the suction pipe are concentrically disposed. In addition, the removal amount of injected drainage increases, providing preferable vision for surgery. 
     According to this structure, the injection pipe is fixed to the inner circumferential surface of the suction pipe in the vicinity of the injection opening. Thus, abnormal noise produced by contact between the injection pipe and the suction pipe caused by vibration at the top end of the injection pipe is prevented by reduction of the vibration thereat. Moreover, movement of the top end of the injection pipe (injection opening) caused by the vibration thereat and resonance of the suction pipe generated by the vibration can be both prevented. Thus, fluid can be accurately injected toward the surgery portion. 
     Application Example 2 
     This application example of the invention is directed to the fluid injection device of the above application example, wherein a mark indicating the position of the injection opening is provided on the suction pipe in the vicinity of the suction opening. 
     According to the structure which eccentrically inserts the injection pipe into the suction pipe, an operator can recognize the position of the injection opening based on the mark indicating the position of the injection opening. Thus, fluid can be accurately injected toward the surgery portion. 
     Application Example 3 
     This application example of the invention is directed to the fluid injection device of the above application example, wherein the mark is a notch formed in such a position as to overlap with the periphery of the suction opening, or a through hole opened in the vicinity of the suction opening. 
     The mark may be a seal or the like which indicates the position of the injection opening provided in the vicinity of the suction opening. When a notch as the mark is formed in such a position as to overlap with the periphery of the suction opening, the notch not only allows recognition of the position of the injection opening but also increases the size of the suction opening by the amount corresponding to the notch. 
     When the mark is constituted by a through hole, excised tissues on the side surface as well as excised tissues at the top end can be removed by suction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  illustrates the structure of a fluid injection device as a surgical instrument according to a first embodiment. 
         FIG. 2  is a cross-sectional view illustrating cross sections of a pulse generator, an injection pipe, and a suction pipe cut in the injection direction of fluid according to a first example. 
         FIGS. 3A and 3B  are cross-sectional views showing cross sections taken along a line A-A in  FIG. 2 , wherein:  FIG. 3A  illustrates the first example; and  FIG. 3B  illustrates a related art. 
         FIG. 4  is a partial cross-sectional view illustrating the structure of an injection pipe and a suction pipe according to a second example. 
         FIG. 5  is a partial cross-sectional view illustrating the structure of an injection pipe and a suction pipe according to a third example. 
         FIG. 6  is a partial cross-sectional view illustrating the structure of an injection pipe and a suction pipe according to a fourth example. 
         FIG. 7  is a partial cross-sectional view illustrating the structure of an injection pipe and a suction pipe according to a fifth example. 
         FIG. 8  is a partial cross-sectional view illustrating the structure of an injection pipe and a suction pipe according to a sixth example. 
         FIGS. 9A and 9B  show top ends of an injection pipe and a suction pipe according to a seventh example, wherein:  FIG. 9A  is a cross-sectional view; and  FIG. 9B  is a front view as viewed from the top ends (in the direction indicated by an arrow E). 
         FIG. 10  is a front view illustrating a top end of a suction pipe according to an eighth example. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENT 
     An exemplary embodiment according to the invention is hereinafter described with reference to the drawings. 
     The figures referred to in this embodiment are shown only as schematics the reduction scales of which for components and parts in the vertical and horizontal directions are different from the actual scales for convenience of easy understanding of the figures. 
     First Embodiment 
       FIG. 1  illustrates the structure of a fluid injection device as a surgical instrument according to a first embodiment. Thus, fluid used in this embodiment described herein is constituted by physiological salt water. As illustrated in  FIG. 1 , a fluid injection device  1  includes a fluid supply container  2  for containing fluid, a supply pump  10  as a fluid supply unit, a pulse generator  20  for converting fluid supplied from the supply pump  10  into pulse flow (hereinafter referred to as pulse flow as well), an injection pipe  70  communicating with the pulse generator  20 , a suction pipe  80  projecting from the pulse generator  20 , a suction pump  11  as a suction unit, and a drainage container  3  for containing sucked drainage and excised tissues. The pulse generator  20 , the supply pump  10 , and the fluid supply container  2  are connected by a fluid supply tube  4 . The suction pipe  80 , the suction pump  11 , and the drainage container  3  are connected by a suction tube  5 . 
     The pulse generator for generating pulse flow may be operated by various systems such as a piezoelectric system including a piezoelectric element, and a bubble jet (trademark) system as long as the systems can convert fluid into pulse flow and inject the pulse flow as pulses. In the following explanation, a pulse generator operated by the piezoelectric system is discussed as an example. 
     The injection pipe  70  has an injection channel  71  communicating with a fluid chamber  60  formed within the pulse generator  20 . An injection opening  72  having a narrowed flow channel is opened at the top end of the injection pipe  70 . 
     The injection pipe  70  is eccentrically inserted into the suction pipe  80  such that the outer circumferential surface of the injection pipe  70  contacts the inner circumferential surface of the suction pipe  80 . The injection pipe  70  is fixed to the inner circumferential surface of the suction pipe  80  in the vicinity of the injection opening  72  by bonding or other fixing methods. The clearance formed between the inner circumferential surface of the suction pipe  80  and the outer circumferential surface of the injection pipe  70  corresponds to a suction channel  81  and a suction opening  82 . The injection pipe  70  is rigid enough to avoid deformation during injection of fluid. It is preferable that the suction pipe  80  is more rigid than the injection pipe  70 . 
     The flow of fluid within the fluid injection device  1  constructed as above is now briefly explained. Fluid contained in the fluid supply container  2  is sucked by the supply pump  10 , and supplied through the fluid supply tube  4  toward the pulse generator  20  at a constant pressure. The pulse generator  20  has the fluid chamber  60 , a piezoelectric element  30  as a volume varying unit for varying the volume of the fluid chamber  60 , and a diaphragm  40 . The pulse generator  20  generates pulse flow within the fluid chamber  60  by driving the piezoelectric element  30 , and injects the fluid having passed through the injection channel  71  as pulses from the injection opening  72  at high speed. 
     While the operation of the pulse generator  20  is stopping, that is, while the volume of the fluid chamber  60  is not being changed, the fluid supplied from the supply pump  10  at the constant pressure passes through the fluid chamber  60  and goes out of the injection opening  72  as continuous streams for injection. 
     The pulse flow herein refers to flow of fluid which has a constant flow direction but has a flow amount or a flow speed varying periodically or irregularly. The pulse flow includes intermittent flow where fluid repeats a cycle of flow and stop. However, the pulse flow may be flow other than the intermittent flow as long as the flow amount or the flow speed of fluid changes periodically or irregularly. 
     Similarly, injection of fluid as pulses refers to injection of fluid whose flow amount or moving speed varies periodically or irregularly. The injection as pulses includes intermittent injection which repeats a cycle of injection and non-injection of fluid, for example. However, the injection as pulses may be injection other than the intermittent injection as long as the flow amount or the moving speed of fluid to be injected changes periodically or irregularly. 
     The method of suction is now explained. The fluid injected from the injection opening  72  remains on the surgery portion as drainage. In addition, excised tissues exist on the surgery portion. These drainage and excised tissues are sucked by the suction pump  11 , and conveyed from the suction opening  82  through the suction channel  81  and the suction tube  5  into the drainage container  3 . The drive of the suction pump  11  may be interlocked with the drive of the pulse generator  20 , or may be periodical intermittent drive. 
     There are a plurality of shapes and structures considered as suitable for those of the injection pipe  70  and the suction pipe  80 . These shapes and structures are herein discussed as specific examples while referring to the respective drawings. 
     First Example 
     A first example is now described. 
       FIG. 2  is a cross-sectional view showing cross sections of the pulse generator, the injection pipe, and the suction pipe cut in the injection direction of fluid according to the first example. The pulse generator  20  includes an inlet channel  61  through which fluid is supplied from the supply pump  10  via the fluid supply tube  4  toward the fluid chamber  60 , the piezoelectric element  30  and the diaphragm  40  as the volume varying unit for varying the volume of the fluid chamber  60 , and an outlet channel  62  communicating with the fluid chamber  60 . 
     The diaphragm  40  is constituted by a disk-shaped thin metal plate and fixed by tight contact with a lower case  50  and an upper case  52 . In this embodiment, the piezoelectric element  30  is a laminated-type piezoelectric element which has one end fixed to the diaphragm  40  via an upper plate  35  and the other end fixed to a bottom plate  51 . 
     The fluid chamber  60  is a space defined by the diaphragm  40  and a concave portion formed on the surface of the upper case  52  opposed to the diaphragm  40 . The outlet channel  62  opens approximately at the center of the fluid chamber  60 . 
     The upper case  52  and the lower case  50  are combined into one body by junction of the opposed surfaces of the upper case  52  and the lower case  50  (with the diaphragm.  40  interposed therebetween in the example of  FIG. 2 ). The injection pipe  70  which has the injection channel  71  communicating with the outlet channel  62  engages with the upper case  52 . The injection opening  72  having a reduced channel diameter is provided at the top end of the injection pipe  70 . The injection opening  72  may be formed by a nozzle. 
     The suction pipe  80  as a jacket pipe for the injection pipe  70  projects from the upper case  52 . An opening  83  penetrating through the side wall of the suction pipe  80  is formed in the vicinity of the root end of the suction pipe  80  close to the pulse generator  20 , and the suction tube  5  is attached to the opening  83  in such a condition as to communicate with the opening  83 . For an operator who holds the pulse generator  20  while performing operation, the maneuverability improves when the extending direction of the suction tube  5  in the vicinity of the pulse generator  20  is equalized with the extending direction of the fluid supply tube  4 . 
     As illustrated in the figure, the injection pipe  70  is eccentrically inserted into the suction pipe  80 . Thus, the outer circumferential surface of the injection pipe  70  and the inner circumferential surface of the suction pipe  80  contact each other, or are disposed with a small clearance left therebetween in the range of the length of the suction pipe  80 . This condition is now explained with reference to  FIGS. 3A and 3B . 
       FIGS. 3A and 3B  are cross-sectional views illustrating cross sections cut along an A-A line in  FIG. 2 .  FIG. 3A  shows the cross section in this example, while  FIG. 3B  shows the cross section in a related art. As illustrated in  FIG. 3A , the outer circumferential surface of the injection pipe  70  and the inner circumferential surface of the suction pipe  80  contact each other. The clearance formed between the flow channel of the suction pipe  80  and the outer circumferential surface of the injection pipe  70  corresponds to the suction channel  81 . When the flow channel diameter of the suction pipe  80  and the outside diameter of the injection pipe  70  are d 1  and d 2 , respectively, the length (d 1 −d 2 ) becomes the maximum size of the suction channel  81 . 
     According to the technology shown in JP-A-1-313047, the injection pipe  70  is inserted concentrically with the suction pipe  80 . In this case, the maximum size of the suction channel  81  becomes (d 1 −d 2 )/2. Thus, even when the total areas of the respective suction channels  81  in the structures of this example and JP-A-1-313047 are the same, the size of the suction channel  81  in the eccentric structure as in this example becomes larger than the size of the suction channel  81  in JP-A-1-313047. This relationship between the suction channels  81  in this example and in JP-A-1-313047 similarly applies to the relationship between the sizes of the suction openings  82  in both of the structures. 
     According to this example, the outer circumferential surface of the injection pipe  70  contacts the inner circumferential surface of the suction pipe  80 . In this structure, the injection pipe  70  is inserted into the suction pipe  80  and fixed thereto by an adhesive or the like under the condition of contact between the inner circumferential surface of the suction pipe  80  and the outer circumferential surface of the injection pipe  70 . Then, the suction pipe  80  and the injection pipe  70  fixed to each other are attached to the upper case  52  with press fit for assembly. In this case, as illustrated in  FIG. 2 , the injection pipe  70  is forced into the upper case  52  with the root end of the injection pipe  70  on the upper case  52  side projecting from the root end of the suction pipe  80 , in which condition the suction pipe  80  engages with the upper case  52  with play. Then, the fitted pipes  70  and  80  are fixed to the upper case  52  by using an adhesive or the like. It is preferable that the sealing of the fixation between the upper case  52  and the injection pipe  70  and the suction pipe  80  is reinforced by using an adhesive, a solder or the like. 
     It is preferable that the injection pipe  70  and the suction pipe  80  are fixed to each other for the entire contacting areas of the respective pipes  70  and  80  in the length directions. However, the pipes  70  and  80  are only required to be fixed at least in the area around the top end of the injection opening  72  (a B range in  FIG. 2 ). In this case, the injection pipe  70  and the suction pipe  80  are inserted into the upper case  52  in this order, and then the range B in the figure is fixed by bonding using an adhesive or a solder, or fixed by using a fixing method such as welding. 
     It is preferable that each flow channel size of the opening  83  provided on the suction pipe  80  and the suction tube  5  is made equal to or larger than the cross-sectional area of the flow channel of the suction opening  82 . 
     The pulse flow injection operation performed by the pulse generator  20  according to this example is now explained with reference to  FIGS. 1 and 2 . Fluid is supplied to the inlet channel  61  at a constant pressure by the function of the supply pump  10 . The fluid supply amount from the supply pump  10  is only required to be approximately the same amount as that of the pulse flow injection amount from the injection opening  72 . While the piezoelectric element  30  is not actuating, fluid flows into the fluid chamber  60  by the difference between the discharging force of the supply pump  10  and the resistance of the entire flow channel of the inlet channel  61 . 
     When the piezoelectric element  30  rapidly expands in the vertical direction with respect to the surface of the diaphragm  40  on the fluid chamber  60  side in response to a drive signal inputted to the piezoelectric element  30 , the volume of the fluid chamber  60  decreases. As a result, the pressure within the fluid chamber  60  sharply increases to reach several tens atms. 
     In this case, the increase in the flow amount of the fluid discharged from the outlet channel  62  becomes larger than the decrease in the flow amount of the fluid flowing from the inlet channel  61  into the fluid chamber  60 , thereby generating pulse flow in the injection channel  71 . This pressure change produced at the time of the discharge is transmitted through the injection pipe  70  to allow injection of pulsed fluid at high speed from the injection opening  72  at the top end. 
     As described above, the injection pipe  70  is eccentrically inserted into the suction pipe  80  according to the first example. In this case, each size of the suction channel  81  and the suction opening  82  corresponds to the difference between the inside diameter of the suction pipe  80  and the outside diameter of the injection pipe  70 . Thus, each size of the suction channel  81  and the suction opening  82  in the eccentric structure becomes larger than the corresponding size in the concentric structure. Accordingly, larger excised tissues can be sucked in the structure of the eccentrically disposed the injection pipe  70  and the suction pipe  80  than in the concentric structure. Moreover, the drainage removal amount of injected fluid increases, which provides preferable vision for surgery. 
     According to this example, the injection pipe  70  is fixed to the inner circumferential surface of the suction pipe  80  in the vicinity of the injection opening  72 . Thus, abnormal noise generated by contact between the injection pipe  70  and the suction pipe  80  caused by vibration at the top end of the injection pipe  70  during injection of pulse flow can be prevented. Moreover, resonance of the suction pipe  80  generated by the vibration at the top end of the injection pipe  70  (injection opening) is avoided, allowing accurate injection of fluid toward the surgery portion. 
     While the structure which fixes the suction pipe  80  to the upper case  52  has been discussed in this example, such a structure which expands the upper case  52  such that the upper case  52  can function as a suction pipe is allowed. 
     The position and extending direction of the suction tube  5  are not specifically limited. However, since the operator holds the pulse generator  20  for performing operation, the system becomes well-balanced during operation and provides higher maneuverability when the suction tube  5  and the fluid supply tube  4  extend along each other in the vicinity of the pulse generator  20 . 
     Second Example 
     A second example is now described with reference to the drawings. While the injection pipe  70  and the suction pipe  80  are provided eccentrically for the entire lengths of the pipes  70  and  80  in the first example described above, the second example is different from the first example in that only the top end areas of the injection pipe  70  and the suction pipe are eccentrically disposed with the root end areas concentrically positioned. In the explanation of the second example, similar reference numbers are given to parts similar to the corresponding parts in the first example, and the different points between the first example and the second example are chiefly discussed. 
       FIG. 4  is a partial cross-sectional view illustrating the structures of the injection pipe and the suction pipe according to the second example. The root end of the suction pipe  80  is fixed to the upper case  52  with press fit. The root end of the injection pipe  70  is fixed to the upper case  52  with press fit in such a condition as to be concentric with the suction pipe  80 . The top ends (the B area in the figure) of the injection pipe  70  and the suction pipe  80  are fixed to each other by bonding such as an adhesive and a solder, or by using a fixing method such as welding. 
     According to this structure, the condition visually recognized on the top end side is similar to the condition shown in  FIG. 3A , and the size of the suction opening  82  in this structure becomes larger than the corresponding size in the concentric structure. Thus, larger excised tissues can be sucked than in the related art which concentrically disposes the top ends of the injection pipe  70  and the suction pipe  80 . Since clogging with excised tissues is easily caused at the suction opening  82 , the sucking capability can be increased by widening the suction opening  82 . 
     According to the structure which concentrically disposes the root ends of the injection pipe  70  and the suction pipe  80 , the upper case  52  can be more easily processed than in the structure which fixes the eccentrically disposed pipes  70  and  80  to the upper case  52  as in the first example. Thus, the respective pipes  70  and  80  can be more easily attached to the upper case  52  with press fit. 
     The injection pipe  70  may be bended beforehand and urged toward the inner circumferential surface of the suction pipe  80  by the elastic force of the injection pipe  70 . In this case, the suction pipe  80  is made rigid enough to resist the elastic force of the injection pipe  70  and to prevent vibration of the suction pipe  80 . According to this structure, the process for fixing the top ends of the pipes  70  and  80  can be eliminated. 
     Third Example 
     A third example is now described with reference to the drawings. The third example is different from the second example in that the position of connection between the suction pipe  80  and the suction tube  5  is different from the corresponding position in the second example. In the following explanation, similar reference numbers are given to parts similar to the corresponding parts in the second example, and the different points between the second example and the third example are chiefly discussed. 
       FIG. 5  is a partial cross-sectional view illustrating the structures of the injection pipe and the suction pipe according to the third example. The relationship between the injection pipe  70  and the suction pipe  80  is similar to that relationship in the second example. According to the second example, the top ends of the injection pipe  70  and the suction pipe  80  are eccentrically disposed and fixed to each other. Thus, the area of the suction channel  81  other than the fixed portion gradually decreases toward the root end, and becomes a channel of the same size as that size in the concentric structure in the vicinity of the opening  83  where the suction tube  5  is disposed. However, it is preferable that the opening  83  is provided in the range where the suction channel  81  is wide. 
     According to this example, therefore, an opening position C is disposed at a position where the suction channel  81  is relatively wide. In this structure, a tube fitting  90  having a connection channel  91  is used. The connection channel  91  is bended approximately in an L shape such that the suction tube  5  extends along the suction tube  80  and further along the fluid supply tube  4  (see  FIG. 2 ). In this case, the suction tube  5  may be formed in the manner shown in the figure, or may be bound to the suction pipe  80  by using a binding band (not shown) around a point D in the figure when the suction tube  5  has sufficient elasticity. 
     According to this structure, the opening  83  is disposed at the position where the suction channel  81  becomes wider than in the concentric structure. Thus, the sucking capability does not lower. Moreover, in case of this structure, the area of the suction tube  5  around the tube fitting  90  extends along the suction pipe  80 , and the area of the suction tube  5  around the pulse generator  20  extends along the fluid supply tube  4 . Thus, the pulse generator  20  can be easily held, which does not deteriorate the maneuverability. 
     Furthermore, the structure of the upper case  52  to which the root ends of the injection pipe  70  and the suction pipe  80  are attached can be simplified. 
     It is possible to form the tube fitting  90  and the suction pipe  80  integrally with each other, or form the tube fitting  90  and the suction tube  5  integrally with each other. 
     Fourth Example 
     A fourth example according to the invention is now described with reference to the drawings. The fourth example is different from the third example in that the injection pipe  70  is bended at a position within the area between the root end and the top end to fix the top ends of the injection pipe  70  and the suction pipe  80  to each other. In the following explanation, similar reference numbers are given to parts similar to the corresponding parts in the third example, and the different points between the third example and the fourth example are chiefly discussed. 
       FIG. 6  is a partial cross-sectional view illustrating the structures of the injection pipe and the suction pipe according to the fourth example. The injection pipe  70  and the suction pipe  80  are attached to the upper case  52  such that the pipes  70  and  80  become concentric with each other similarly to the second example and the third example described above. According to this example, the injection pipe  70  is bended approximately at the center. The area of the injection pipe  70  between the top end and a bended portion  70   a  contacts the inner circumferential surface of the suction pipe  80 , and is fixed thereto by bonding such as an adhesive and a solder, or by using a fixing method such as welding. The area of the injection pipe  70  between the bended portion  70   a  and the root end is approximately concentric with the suction pipe  80 . 
     The opening  83  formed on the suction pipe  80  (the opening position C) is disposed at a position shifted from the bended portion  70   a  toward the top end and communicates with the suction tube  5  via the tube fitting  90 . The suction tube  5  extends along the fluid supply tube  4 . 
     According to this structure, the opening  83  is provided at a position within the area between the suction opening  82  and the bended portion  70   a  where the suction channel  81  is wide. Thus, the suction channel  81  having approximately the same size as that of the suction opening  82  can be formed, which allows larger excised tissues to be removed by suction than in the concentric structure. 
     When the bended portion  70   a  is positioned closer to the root end, the opening  83  of the suction pipe  80  can be shifted toward the pulse generator  20 . In this case, the pulse generator  20  can be easily held, which improves the maneuverability. When the bended portion  70   a  is disposed within the area of the upper case  52 , the opening  83  can be provided on the upper case  52  similarly to the structure of the second example (see  FIG. 4 ). 
     Fifth Example 
     A fifth example is now described with reference to the drawings. The fifth example is different from the first example in that the suction pipe  80  linearly formed in each of the first through fourth examples is bended in the middle area. In case of an abdominal cavity surgery or the like performed by using the fluid injection device  1 , there is a possibility that the surgery portion is not located on a straight line extending from the position on the body surface into which the suction pipe  80  is inserted. In this case, the top ends of the injection pipe  70  and the suction pipe  80  are required to be located at bended positions with respect to their root ends. This example is appropriate for this case. In the following explanation, similar reference numbers are given to parts similar to the corresponding parts in the second example on which the fifth example is based. 
       FIG. 7  is a partial cross-sectional view illustrating the structures of the injection pipe and the suction pipe according to the fifth example. The suction pipe  80  is bended at a middle position in the area between the top end and the root end. The injection pipe  70  is bended along the inner circumferential surface of the suction pipe  80 , and fixed to the inner circumferential surface of the suction pipe  80  in the area around the injection opening  72  (the B range in the figure) by bonding using an adhesive, a solder or the like, or by a fixing method such as welding. 
     There is a method which bends the injection pipe  70  in accordance with the shape of the suction pipe  80 . In practice, however, insertion of a bended tube into another bended tube is difficult from the viewpoint of structure. Thus, the substantially linear injection pipe  70  is initially fixed to the upper case  52  with press fit, and then the suction pipe  80  is inserted from the injection opening  72  side. In this case, the top end of the injection pipe  70  contacts a slope  80   a  at the bending position of the suction pipe  80 , and then is bended in accordance with the shapes of the slide  80   a  and a bended portion  80   b  with to obtain a shape shown in  FIG. 7  when the root end of the suction pipe  80  reaches the upper case  52 . In case of the abdominal cavity surgery, each length of the injection pipe  70  and the suction pipe  80  is approximately in the range from 200 m to 400 mm. Thus, the actual bending angle becomes a gentler angle than the angle in the condition shown in the figure. 
     According to this example, therefore, the top ends of the injection pipe  70  and the suction pipe  80  can be eccentrically disposed even when the top ends of the injection pipe  70  and the suction pipe  80  are located at bended positions with respect to their root ends in correspondence with the surgery portion or the surgery method. Thus, the suction opening  82  in this structure becomes wider than in the concentric structure. In this example, the bended portion of the suction channel  81  has an area smaller than the suction opening  82 . However, since the outer shape of the injection pipe  70  is circular, the resistance of the flow channel is small enough to avoid lowering of the capability of sacking the excised tissues. 
     According to this example, the injection pipe  70  is inserted along the inner circumferential surface of the bended suction pipe  80 . Thus, the top end of the injection pipe  70  is urged toward the inner circumferential surface of the suction pipe  80  by the elastic force of the injection pipe  70 . Accordingly, the top end of the injection pipe  70  is not required to be fixed as long as the urging force is large enough to prevent vibration. Considering this point, the rigidity of the suction pipe  80  is made larger than the rigidity of the injection pipe  70 . 
     Sixth Example 
     A sixth example is now described with reference to the drawings. The sixth example is different from the first through fifth examples in that the fluid injection direction which extends on a straight line drawn from the injection channel  71  or in parallel with the injection channel  71  in each of the first through fifth examples is inclined to the injection channel  71 . There is a case in which excision is performed at a position shifted from the extending direction of the suction pipe  80  depending on the surgery portion. This example is appropriate for this case. In the following explanation, similar reference numbers are given to parts similar to the corresponding parts in the first example on which the sixth example is based. 
       FIG. 8  is a partial cross-sectional view illustrating the structures of the injection pipe and the suction pipe. The top ends of the injection pipe  70  and the suction pipe  80  are bended, and the injection pipe  70  follows the inner circumferential surface of the bended portion of the suction pipe  80 . The area of the injection pipe  70  around the injection opening  72  is fixed to the inner circumferential surface of the suction pipe  80  by using an adhesive, a solder or the like, or by a fixing method such as welding. 
     When the flow channel diameter of the suction pipe  80  and the bending height of the injection pipe  70  are d 1  and h, respectively, the flow channel diameter d 1  is determined such that the relationship h&lt;d 1  holds. This arrangement allows insertion of the injection pipe  70  into the suction pipe  80 . 
     According to this structure, excision and removal of excised tissues by suction at a position shifted from the extending direction of the suction pipe  80  can be achieved in accordance with the surgery portion. 
     The structure in this example may be applied to each structure of the first through fifth examples. 
     Seventh Example 
     A seventh example is now described with reference to the drawings. Since the injection opening  72  is disposed eccentrically to the suction opening  82  as described in each of the examples, it is difficult for the operator to directly recognize the injection opening  72  by visual check. For overcoming this drawback, a feature of the seventh example resides in that a mark representing the position of the injection opening  72  is provided in the vicinity of the suction opening  82 . 
       FIGS. 9A and 9B  illustrate the top ends of the injection pipe and the suction pipe according to the seventh example.  FIG. 9A  is a cross-sectional view, and  FIG. 9B  is a front view as viewed from the top end (in the direction indicated by an arrow E). As illustrated in  FIGS. 9A and 9B , a notch  73  as a mark is formed on the suction pipe  80  in the vicinity of the injection opening  72 . The notch  73  is formed in such a position and a shape as to overlap with the periphery of the suction opening  82 . Thus, the operator can visually recognize the top end of the injection pipe  70  (injection opening position). 
     The mark may be a notch as shown in the figure, or other marks such as a seal, a small hole, and a paint provided on the outer circumferential surface of the suction pipe  80 . When the mark is the notch  73  as in this example, the operator can directly recognize the position of the injection opening  72  by visual check during operation. Thus, the operator can inject fluid to the accurate surgery portion for excision. 
     Eighth Example 
     An eighth example is now described with reference to the drawings. While the one notch  73  is provided as a mark in the seventh example, the eighth example is different in that the mark is constituted by notches formed in such positions as to overlap with the suction opening or through holes opened in the vicinity of the suction opening. 
       FIG. 10  is a front view illustrating the top end of the suction pipe according to the eighth example. As illustrated in  FIG. 10 , four notches  73   a ,  73   b ,  73   c , and  73   d  are formed on the top end of the suction pipe  80  in such positions as to overlap with the periphery of the suction opening  82 . According to the example shown in  FIG. 10 , the notch  73   a  corresponds to a mark indicating the position of the injection opening  72 . The other notches  73   b  through  73   d  are provided to supplement the sucking function of the suction opening  82 . Thus, the notch  73   a  has a position and shape appropriate for a mark, while the other notches  73   b  through  73   d  have positions and shapes allowing suction of excised tissues. The notches  73   a  through  73   d  may be through holes (not shown) penetrating the side surface of the top end of the suction pipe  80 . 
     Accordingly, the mark indicating the position of the injection opening  72  can be provided in the vicinity of the suction opening  82  by formation of the notches  73   a  through  73   d . These notches  73   a  through  73   d  can further supplement the size of the suction opening  82 , and thus can increase the capability of sucking excised tissues. 
     Furthermore, the through holes formed in the vicinity of the suction opening  82  can remove excised tissues existing on the side surface of the top end by suction.