Abstract:
A flap valve for a trocar system including a valve housing ( 12 ) that is proximally attachable to a guide tube ( 10 ), a lead-through opening ( 30 ) formed in the valve housing ( 12 ), and a pivotally mounted flap valve ( 46 ). The flap valve ( 46 ) is manually pivotable from a “closed” position to an “open” position via a slide rod. The slide rod ( 52 ) is mebedded in the body ( 12 ), is radially slidable and contacts with its inner end an actuation area of the flap valve ( 46 ).

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention concerns a flap valve for a trocar system according to the preamble of a patent 1. 
   2. Description of the Related Art 
   Trocar systems are being used in minimally invasive surgery to enable entrance to a body cavity, for example, into the visceral cavity. For this procedure, a guide tube (trocar cannula) with a trocar (obturator) inserted therein is passed through the abdominal wall. Subsequently, the trocar is removed and the guide tube remains as an access canal to the visceral cavity. In order to perform surgical procedures in the visceral cavity, it typically is insufflated. To avoid gas leakage from the visceral cavity, a valve is placed at the extracorporeal remaining proximal end of the guide tube, which closes automatically if no instrument is inserted. 
   To enable the insertion of a delicate instrument and avoid the entanglement of instruments during extraction, flap valves are used that can be manually opened. The flaps on the flap valves include part of a valve that closes, spring-biased, on an aperture, which aligns axially with the guide tube. The flap is pivotally operated against a spring force, perpendicularly to the exocentric pivoting axis of the lead-through opening. 
   From U.S. Pat. No. 4,654,030 it is known to affix a valve non-rotatingly (torque-proof) upon a pivot axle, and to provide a pivot lever on the end of the axle projecting out from the valve body for the manual actuation of the valve. The manipulation of the flap valve is unfavorable, because the surgeon has to support the trocar system with one hand and use the other hand for pivoting the valve. 
   In DE 3923243 C2, a flap valve of the previously mentioned type is disclosed. This flap valve is pivoted into the open position with the aid of a sliding rod. The sliding rod is slidable parallel to the axis of the releasable lead-through-opening. To operate the flap, the housing-inner end of the sliding rod engages the flap between the valve part and its pivoting axis. The space needed to operate the slide rod enlarges the radial and axial measurements of the body of the flap valve. Because of spatial reasons the slide rod must be attached very close to the middle axis of the body, so the handling of the slide rod is ergonomically unfavorable. 
   The object of the invention is to provide a flap valve for a trocar system with a compact configuration that allows an ergonomically favorable handling of the tool. 
   This task is inventively accomplished by a flap valve having the characteristics of Patent 1. 
   Preferred embodiments of the invention are set forth in the dependent claims. 
   SUMMARY OF THE INVENTION 
   In the inventive flap valve, the slide rod operating the flap is introduced radially slidable into the housing. The flap valve can thus be opened simply by pushing a radially positioned push button. Therefore, it becomes possible to handle the trocar system and operate the flap valve with one hand in an ergonomically favorable manner. The housing of the flap valve and consequently the trocar system can be held, for example, between the index and middle fingers, whereas the radial operation of the flap valve can be by the thumb. The flap is constructed in the manner of a two-armed lever. The slide rod engages an actuation area that is located on one arm of the flap. The other arm, relative to the pivoting axis of the flap, includes the valve part. Preferably, the operating area is developed immediately in the area of the pivoting axis. Therefore, the operating of the flap doesn&#39;t require any additional radial space and the outside diameter of the body can stay at a minimum. In addition, a pivoting of the flap by 90° between the “closed” and “open” positions is possible through a smaller radial stroke—another advantage of the compact design of the flap valve. Especially, the radial slide rod allows a significant reduction of the axial dimensions of the flap valve. 
   In a preferred embodiment, the actuation area of the flap is in the form of a curved surface having such a shape that the area that slide rod engages has, in any pivoted position of the flap, as sufficiently large angle to the slide rod axis to initiate a turning moment in the pivoting direction of the flap. Through the pivoting movement of the flap, the actuation area practically slides underneath the inward facing end of the slide rod. Thus, there is a constant application of force and a constant torque over the total linear range of the slide rod and therefore the total pivoting range of the flap. This is of substantial advantage for an ergonomic operation of the flap valve. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention will be explained in detail in the following on the basis of the embodiments shown in the figures, wherein there is shown: 
       FIG. 1 : a side view of the trocar system, 
       FIG. 2 : an axial view of the trocar system viewed from the proximal end, 
       FIG. 3 : an axial section of the trocar system, 
       FIG. 4 : an axial view of the flap valve from the distal side, 
       FIG. 5 : an axial section through the flap valve in the “closed” position 
       FIG. 6 : an axial section through the flap valve in the “open” position 
       FIG. 7 : an enlarged representation of the flap in side view 
       FIG. 8 : a corresponding representation of the flap viewed from above 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The trocar system shown in  FIGS. 1 through 3  includes a guide tube  10 , containing an inserted trocar, not visible in the drawing, serving as instrument channel and access channel for minimally invasive surgery, for example, when inserted through the visceral cavity. 
   On the proximal end of the guide tube  10  a housing  12  is seated axially flush, comprising a base part  14  and a flap body  16 . An insufflation stop-cock or valve  18  leads into the base part of the housing, through which gas can be injected into the visceral cavity. The flap body contains the flap valve, which is described in detail below. A hollow insertion shaft  20  is proximally screwed in sealed manner into the flap body  16 , which is aligned axially with the insertion tube  10  and also exhibits the same inner diameter. On the proximal end of the insertion shaft  20 , a soft elastic rubber covering  22  is attached, which exhibits a central opening and a diameter slightly smaller than the inner diameter of the insertion shaft  20 . 
   In  FIGS. 4 through 6 , the flap body  16  together with the therein arranged flap valve is shown in detail. The flap body  16  has a distal cylindrical chamber  26  that attaches at the base to the base part  14 , into which a valve receptacle  24  is fitted. The chamber transitions co-axially into an opening, which exhibits an inner thread into which the insertion shaft  20  is screwed. The valve receptacle  24  has a lead-through opening  30  with its inner diameter smaller than the diameter of the opening of the body of the flap  16 . Thereby, the valve receptacle  24  serves as an inner shoulder  32 . An elastic gasket bushing  34  is fitted axially between the valve receptacle  24  and the insertion shaft  20 . It is attached between the inner shoulder  32  of the valve receptacle  24  and inner shoulder of the insertion shaft  20 , as shown in  FIG. 3 . The gasket bushing  34  extends co-axially into the lead-through opening  30  of the valve receptacle  24  and serves as the valve seat for the flap valve. 
   Two bearing supports  36  are positioned outside the outer diameter of the lead-through opening  30  on the flap retainer. Between the two bearing supports  36  there remains free a radial receptacle space. Both bearing supports  36  show respectively a flush-running bore  38  in the secant direction. A bearing pin  40  is inserted into the bore of one of the bearing supports. A leg spring  42  is co-axially attached upon the bearing pin  40 . The leg spring  42  is held by a bearing bolt  44  which sits in the bore  38  of the other bearing support  36  and is co-axially screwed on to the bearing pin  40 . The bearing pin  40  and the bearing bolt  44  pivotally hold flap  46 . The flap  46  is housed between the bearing supports through a modeled block which is a lead-through-drilling flush to the bearing bore  38 , and houses the bearing pin  40  with the leg spring. The leg spring  22  has one leg in the valve receptacle  24  and is attached with its other leg to the flap  46 . The leg pin  42 , therefore, provides the flap  46  with a pretension in the pivoting direction, in which the flap  46  gets pivoted against the valve receptacle  24 . 
   The flap  46 , shown in  FIGS. 7 and 8  as a single part, generally consists of a rectangular piece extending from the inner circumference of the chamber  26  radially towards inside and extends beyond the center axis of the flap body  16 . At the radial outer edge of the flap  46 , a mounting block  47  is formed on this distal area. Concentric to the middle axis of the body of the flap  16  and the lead-through opening  30 , the flap  46  shows receptacle  48 , into which a spherical calotte-shaped valve part  50  is screwed. The valve part  50  seals against the gasket bushing  34  when the flap  46 , via the leg spring  42 , is pivoted into the “closed” position, as shown in  FIG. 5 . Shown in  FIG. 5  in the “closed” position, the flap  46  can be pivoted by a 90° turn into the “open” position against the force of the leg spring  42 . In the “open” position, the flap  46  can be completely pivoted together with the valve part  50  in a distal direction, from the cross-section of the lead-through opening  30 . In this “open” position, an instrument can be inserted through the insertion shaft  20 , the lead-through opening  30  with the gasket bushing  34  and the guide tube  10  into the are where surgery is being performed. The instrument can be a surgical instrument, an endoscope or anything similar. 
   The pivoting of the valve  46  from the “closed” position into the “open” position is executed via slide rod  52 . The slide rod  52  is guided radially through the flap body  16 , and is displaceable in the radial direction along a plane perpendicular to the center axis of the flap body  16 . The slide rod  52  is guided in a bushing  54 , which is screwed into the body of the flap  16  radially and from the outside. The outer end of the bushing  54  is enclosed by a co-axial pushbutton  56 . The pushbutton  56  is pressed upon the radial outer end of the slied rod  52 . A helical compression spring is inserted co-axial to the slide rod axially between the bushing  54  and pushbutton  56  and tensions the pushbutton  56  and the therewith firmly connected slide rod  52  in the rest position shown in  FIG. 5 . The slide rod  52  is withdrawn radially from the chamber  26  of the body of the flap  16 . Through manual pressure on to the push button  56 , the slide rod  52  can be pushed into the body of the flap  16  radially against the force of the helical compression spring to operate the flap  56  and pivot from the “closed” position, as shown in  FIG. 5 , into the “open” position, as shown in  FIG. 6 . 
   In order to pivot the flap  46  using the slide rod  52 , the flap  46  is constructed as follows. The pivot axis of the flap  46 , formed by the bearing pin  40  and the bearing bolt  44 , runs through a mounting block  47  and is distally offset from the plane of the flap  46 . Therefore the area of the flap  46  runs eccentric in relation to the pivot axis. The axis of the slide rod  52 , which corresponds with the direction of the linear movement, is constructed in a way that it nearly corresponds with the proximal topside of the flap  46 , when the flap  46  is in the position shown in  FIG. 5 . An actuation area is defined on the flap  46  where the slide rod  52  is in contact with its inward directed end. The actuation area  60  is most easily seen in  FIGS. 7 and 8 . The actuation area  60  is located at the radial outer end of the valve part  50  away from the flap  46 . The actuation area  60  starts at the proximal outer edge of the flap  46 , runs in a distal direction until block  47  and gets increasingly closer to the predetermined pivot axis of the bearing pin  40 . The radial distance of the actuation area  60  from the pivoting axis  40  therefore decreases from the proximal side of the flap  46  toward the mounting block  47 . When starting the opening pivoting movement of the flap  46 , the slide rod  52  pushes against the proximal side of the flap  46 , parallel to the plane thereof, against the actuation area  60 , which runs perpendicular to the plane of the flap area. At the end of the opening pivoting movement however, the slide rod  52  pushes perpendicularly to the plane of the flap area, against the section of the actuation area  60  which almost runs parallel to the plane of the flap area. Consequently, the linear movement of the slide rod  52  gets transformed into an angled pivoting movement of the flap  46 , whereby the slide rod affects the actuation area almost perpendicularly throughout the complete pivoting movement and carries out the optimal pivoting momentum to the flap  46 . 
   As shown in  FIGS. 7 and 8 , the actuation area  60 , in the direction parallel to the pivoting axis, is slightly concavely arched, so it results in a good sliding area for the rounded inner end of the slide rod  52 . 
   An ergonomically favorable handling of the trocar system is possible because a finger grip recess  62  is located at the distal end of the body  12 , on both sides of the guide tube  10 . The body  12  and, therefore, the whole trocar system is supported by positioning the index finger and the middle finger into these finger receptacles. The pushbutton  56  can be pushed with the thumb of the same hand to operate the flap valve.
       10  Guide tube     12  Valve housing     14  Base part of the valve housing     16  Flap body     18  Insufflation valve     20  Insertion hollow shaft     22  Rubber covering     24  Valve receptacle     26  Chamber     28  Inner thread     30  Lead-through opening     32  Inner shoulder     34  Gasket bushing     36  Bearing support     38  Bearing bore     40  Bearing pin     42  Leg pin     44  Bearing bolt     46  Flap     48  Receptacle     50  Valve part     52  Slide rod     54  Bushing     56  Pushbutton     58  Helical compression spring     60  Actuation area     62  Finger grip recess