Abstract:
The device for applying a flowable medium, in particular a tissue adhesive is provided with at least one reservoir ( 16 ) for the medium, wherein said reservoir ( 16 ) comprises an outlet ( 22 ) from which the medium exits when pressure is applied to the medium and/or said reservoir ( 16 ). A pressure-generating element ( 20 ) acts upon the medium and/or said reservoir ( 16 ) and is biased by a biasing means ( 34 ). Said biasing means ( 34 ) can be locked with the aid of a controllable locking means ( 58 ), wherein said locking means ( 58 ) comprises a movable fixing element ( 54 ) which, in at least one fixing position, locks the biasing element ( 34 ) against movements caused by the biasing process, and is movable out of the at least one fixing position to release said biasing element ( 34 ). Further, a release means ( 81 ) for selected release of said locking means ( 58 ) is provided, wherein said release means ( 81 ) comprises a release element ( 82 ) for temporary movement of the fixing element ( 56 ) out of its at least one fixing position.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a device for applying a flowable medium, in particular a single- or multiple-component tissue adhesive. 
     A number of embodiments of application devices for flowable media (pasty or liquid media) are known (EP-B 0 037 393, EP-B-0 210 160, U.S. Pat. No. 4,874,368, U.S. Pat. No. 4,978,336, DE-A-42 23 356, EP-B-0 315 222, WO-A-96/19940, WO-A95/31137 and WO-A-98/40167). According to the application it is sometimes necessary and desirable to dosedly discharge the medium. In the case of application devices for medical tissue adhesives it is particularly desirable that the doses are reproducible and relatively small. This discharged quantity should further be independent of the duration of manual operation of the application device. 
     For hygienic reasons it is further advantageous when the application devices are designed as non-returnable and/or disposable articles. This, in turn, requires the mechanisms for medium discharge in a dosed manner and independent of the application device to be of relatively simple configuration. If, besides the medium, a gas is to be discharged, by means of which the discharged medium can be sprayed onto an article, it is appropriate to control the dosing mechanism for the medium with the aid of the pressurized gas. Such an application device for technical media is known from EP-A-0 548 509. However, said known application device is not suited for use with nonreturnable and/or disposable articles due to its rather complex structure. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an application device for flowable media, the application device displaying a simple structure suitable for configuration of the application device as non-returnable and/or disposable article. 
     According to the invention, the object is solved with an application device provided with 
     at least one reservoir for the medium, the reservoir comprising an outlet from which the medium exits when pressure is applied to the medium and/or the reservoir, 
     a pressure-generating element for applying pressure to the medium and/or the reservoir, 
     a biasing means for biasing the pressure-generating element, the biasing means comprising a movable biasing element which is pneumatically and/or hydraulically biased towards the pressure-generating element and coupled with the latter, 
     a controllable locking means for locking the biasing element, the locking means comprising a movable fixing element which, in at least in one fixing position, locks the biasing element against movements caused by the biasing process and is movable out of the at least one fixing position to release said biasing element, and 
     a release means for selectedly releasing the locking means, the release means comprising a release element for temporarily moving the fixing element of its at least one fixing position. 
     Further aspects of the invention are stated in the subclaims. 
     The flowable medium to be discharged by the device according to the invention is located in a reservoir which comprises an outlet. If the medium is a multiple-component medium, the components of which are to mixed with each other only during the discharge process, a separate reservoir is provided for each component. The medium is hydraulically discharged from the reservoir by pressure application. The pressure acting upon the medium is applied by a pressure-generating element. Said pressure-generating element acts either upon the medium in the reservoir or from outside upon the reservoir which, in this case, must be of flexible configuration. In the first case, in particular a syringe is used as a reservoir, with the piston of the syringe and the piston rod serving as the pressure-generating element. 
     In the device according to the invention the pressure-generating element used for discharging the medium is biased. This is realized by biasing the pressure-generating element towards the reservoir with the aid of a biasing means. Said biasing means operates pneumatically and/or hydraulically, with in particular the pressure of a gas, which may be used for atomizing the discharged medium, being applied. The biasing means comprises a biasing element coupled with the pressure-generating element. Said biasing element is biased towards the pressure-generating element. The freedom of movement of the biasing element is limited by a locking means. In its normal position said locking means blocks the movement of the biasing element towards the pressure-generating means. With the aid of a release means locking of the biasing element can be released selectively and for a predeterminable period of time. Said release means comprises a release element which temporarily sets a fixing element, which locks the biasing element, into a position in which said fixing element releases the biasing element. 
     The biasing means appropriately comprises a medical syringe to the outlet nozzle of which a hose coupled with a compressed-gas source is connected. The piston rod end and the flanges and/or wings of the barrel of the syringe are supported between a fixed point and the biasing element. By application of pressure the piston and the piston rod are pushed out of the barrel and/or biased towards the outside. This pressure is utilized to move the biasing element towards the pressure-application element acting upon the medium reservoir. 
     The locking device is appropriately configured in the form of teeth meshing with each other. For this purpose the biasing means and in particular the biasing element is provided with at least one toothed rack cooperating with a fixing projection of the fixing element. If said fixing projection is in engagement with said toothed rack, movement of the biasing element is blocked. By moving the fixing element such that the fixing device is disengaged from the toothed rack the biasing means and/or the biasing element is released so that it moves in forward direction following the biasing force. Release of the biasing means and/or the biasing element is controlled by the release element which, on its part, moves the fixing element. 
     The toothing, i.e. the succession of teeth of the toothed rack, determines the measure by which the biasing element can move forward when it is released. If it is requested that extremely small fluid quantities are discharged, the toothed rack must display a correspondingly fine toothing. However a fine toothing is of disadvantage in so far as the meshing of the fixing projection with the toothed rack requires a high degree of finishing accuracy. This finishing accuracy is realizable only in plastic injection molded parts with higher efforts being made, which plastic injection molded parts are to be preferably employed in the device according to the invention. The reason for this is that the device according to the invention is to be configured as non-returnable and/or disposable article. Therefore it is advantageous to use toothed racks with a rougher toothing. To be able to discharge small dosing quantities even with such a tooting, it is advantageous to provide two toothed racks instead of one toothed rack at the biasing means and/or the biasing element, said toothed racks being staggered, in particular by a fraction of the distance between the teeth, preferably half the tooth distance. Consequently, the fixing element comprises two fixing projections. Said fixing projections as well as the toothed racks are arranged at opposite sides and/or sides averting each other of the fixing element and/or the biasing element. By reciprocating the fixing element a respective one of the fixing projections alternately meshes with one of the toothed racks. Even in the intermediate states of movement of the fixing element the biasing element is not released such that the desired step-by-step advance movement is limited exclusively by the alternate meshing of the fixing projections with the toothed rack and the staggered toothed rack arrangement. The fixing element is in both fixing positions protected against unintentional movements in that due to the bias a clamping force is exerted via the respective toothed rack on the fixing element. This force suffices to retain the fixing element in engagement with the respective toothed rack. 
     If only one toothed rack is used, mechanical biasing of the fixing element appropriately ensures that said fixing element automatically moves back into the locking position (the fixing projection meshes with the toothed rack) after release of the biasing element. The release element then operates against this biasing force in that it moves the fixing element of the locking device against the biasing force. 
     As has already been stated above, a mechanical coupling exists between the pneumatically and/or hydraulically biased biasing element and the pressure-generating element acting upon the fluid and/or the reservoir for the purpose of discharging the medium. The biasing element can, on the one hand, be directly coupled and/or connected with the pressure-generating element. Alternatively, coupling can be realized by employing an intermediate or connecting element. Said connecting element is appropriately configured as an actuating element for manually moving the pressure-generating element. Said actuating element is supported on the biasing element and can be manually moved relatively to said biasing element and protected against unintentional displacement. The actuating element can advantageously be configured as a spindle in threaded engagement with the biasing element. One end of said spindle is connected via a rotatably supported receiving element and/or a rotatably supported connecting element with the pressure-generating element, whereas the other end comprises a handwheel or a similar handle by means of which the spindle can be rotated. This configuration allows the pressure-generating element to be manually moved alternatively to the biasing element. This offers the advantage that the device according to the invention can optionally be used for manually discharging a medium quantity which is no longer limited in terms of volume. In the case of this application the pressure-generating element is then moved away from the biasing element by operating the spindle. If the reservoir is configured as a syringe, this spindle can also be used for taking in, via the syringe outlet, medium to be discharged from the syringe. The pressure-generating element is moved towards the biasing element by operating the spindle, whereby a vacuum is produced in the barrel of the syringe due to which vacuum the medium to be discharged (later) is taken into the barrel of the syringe. 
     The device according to the invention is preferably accommodated in a pistol-shaped housing, which is appropriate for the purpose of application of the medium and thus for handling purposes. Such a housing comprises a handle at which appropriately a finger-operated actuating element in the form of a pushbutton, lever or the like is arranged. For reasons of space it is further advantageous when in such a housing the reservoir containing the medium is horizontally arranged. This, in turn, means that the pressure-generating element is horizontally arranged either, i.e. moves in parallel to the movement of the actuating element. Since the pressure-generating element is coupled with the biasing element, the biasing force, too, ensures that the biasing element is movable in parallel to the actuating element. This movement of the biasing element is to be effectively blocked and/or selectively released by the fixing element when said fixing element is movable transversely to the biasing element to, on the one hand, block the biasing element and, on the other hand, release the biasing element. In the final analysis, this means that the movement of the actuating element, which releases the biasing element, must be deflected essentially by 90° to move the fixing element in transverse direction. This movement deflection means is appropriately provided with a swivelling element swivelling about a swivelling axis extending transversely to the directions of movement of the release element and the fixing element. Said swivelling element is coupled with the fixing element and comprises a swivelling arm upon which acts the release element. When the release element presses against the swivelling arm, the swivelling element is swivelled about the swivelling axis. Due to the coupling of the swivelling element with the fixing element a linear movement of the fixing element goes along with this swivelling movement. Such an arrangement is suitable for moving the fixing element from a fixing position into a release position. The fixing element is appropriately moved back from the release position into the fixing position with the aid of a biasing force mechanically applied to said fixing element. 
     If a structure with a fixing element alternately movable between two fixing positions is selected as locking and release mechanism, the swivelling element of the movement deflection means comprises two swivelling arms arranged opposite each other, with the release element alternately acting onto these swivelling arms. Owing to that the swivelling element is alternately pivoted in different directions, which results in a movement of the fixing element from the one fixing position into the other fixing position. In this structure the swivelling element has the form of a “T” whose horizontal legs form the two swivelling arms and whose vertical leg is coupled with the fixing element, wherein the swivelling axis is located in the point of intersection of the two legs. 
     As has already be said above, it is sometimes desirable to atomize the medium discharged with the aid of a device according to the invention. This requires synchronous discharge of a gas, wherein the gas should continue to be discharged for a certain time interval after termination of the medium discharge to prevent medium droplets from forming at the outlet of the device. For this purpose a valve controlling the gas discharge is preferably used, the valve being controlled by the pressure of the gas the discharge of which is to be influenced by the valve. While it is desirable that the passage state of the gas discharge valve is assumed as erratically as possible, change-over of the valve from the passage state to the blocking state is to be effected in a delayed manner. This is appropriately realized by employment of a “differential” gas discharge valve whose housing comprises two interconnected chambers with different diameters and/or cross-sectional areas. In the two chambers a piston is arranged. In particular at opposite ends of the two chambers gas inlet openings are arranged to which the pressurized gas-carrying lines are connected. In the chamber with the smaller cross-section a gas outlet is located, while the chamber with the larger cross-section contains a vent hole to be opened when required. In the normal state said vent hole is closed by a closing element. 
     In the blocking state of the valve the vent hole is closed. Since the associated chamber (hereinafter referred to as first chamber) has a larger cross-section than the other chamber (hereinafter referred to as second chamber) and the gas pressure is identical in both chambers, a larger force acts upon the front face of the piston located in the first chamber than upon the front face of the piston located in the second chamber. Consequently, the piston is displaced towards the second chamber until it bears upon a limit stop defined by a shoulder-shaped tapered area of the housing. In this piston position the piston seals the gas outlet of the second chamber. 
     By opening the vent hole the pressure in the first chamber is abruptly reduced. In the second chamber the overall gas pressure still prevails. Consequently, the piston moves into the first chamber whereby the gas outlet of the second chamber is cleared. Now the gas at the gas inlet of the first chamber is fed via the gas outlet of the first chamber; the valve is in its passage position. 
     As soon as the vent hole is closed again, the pressure in the first chamber rises again, namely to the value of the pressure in the second chamber. Due to the larger piston front area in the first chamber the piston moves again towards the second chamber until, in its final position, it closes the gas outlet. The velocity at which this process takes place depends, on the one hand, on the ratio of the front face sizes of the piston, and, on the other hand, on the rate at which the gas flows into the first chamber. This rate can be limited and adjusted by a flow restrictor or a similar flow rate-determining element such that the valve displays the desired time switching characteristic. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Hereunder the invention is explained in detail with reference to the drawings in which: 
     FIG. 1 shows a side view of the overall setup of the device, 
     FIG. 2 shows a detail of FIG. 1, 
     FIG. 3 shows the state of the device immediately prior to application of the medium, 
     FIG. 4 shows a detail of FIG. 3, 
     FIG. 5 shows a top view of the device according to FIG. 3, 
     FIG. 6 shows the device in the state after initial operation of the actuating element and immediately before exit of the medium, 
     FIG. 7 shows the state of the device when the actuating element is in an intermediate position, and in the phase in which the medium exits, 
     FIG. 8 shows the state of the device with fully pushed-through actuating element and stopped medium discharge, 
     FIG. 9 shows the state of the device after complete release of the actuating element, 
     FIGS. 10 and 11 show enlarged representations of the locking and release mechanisms, and 
     FIGS. 12 to  25  show perspective representations as well sectional representations of the actuating element and details of said actuating element cooperating with the movement coupling of the actuating and release element with the fixing element in different phases of manual operation of the actuating element. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The general setup of the device  10  according to the invention is explained in detail below with reference to FIGS. 1 to  5 . The device  10  shown in the drawing serves for dosed discharge of a two-component tissue adhesive which is atomized with the aid of a gas. The device  10  comprises a housing  12  in which a double chamber discharge device  14  can be accommodated as shown in FIG.  5 . Said device  14  is described in WO-A-98/10703 the contents of which is incorporated herein by reference. Said device  14  comprises two reservoirs  16  configured as syringe bodies in which pistons  18  are slidingly displaceable, said pistons  18  being arranged at piston rods  20 . The outlets  22  of the syringe bodies  16  are connected via a special three-way valve  24  with the inlets of a head piece  26  at whose outlet a multiple-lumen catheter  28  is located. Further, the connecting head  26  comprises a gas connection  30 . The setup of the three-way valves  24  is described in detail in WO-A-98/10703. Because of these details and the overall setup of the device  14  reference is made to the contents of this printed publication. 
     As can be seen from the above description, the two-component tissue adhesive is hydraulically discharged. The pistons  18  with piston rods  20  can be regarded as pressure-generating elements. A biasing means  34  acts via a connecting element  32  upon the piston rods  20 , said biasing means  34  comprising a biasing element  36 . Said biasing element  36  is connected via the connecting element  32  with the piston rods  20 . Further, the biasing element is biased towards the piston rods  20 , which, in this case, is carried out pneumatically. The flanges  42  of the syringe body  38  of a syringe  40  are supported on the biasing element  36 . The piston rod  44  of said syringe  40  is supported on a locating bearing  46  of the housing  12 . To the syringe outlet  48  a hose  50  is connected which is connected via a Y-type connector  52  with the connecting hose  54  coming from an external compressed-gas source. By means of the pressure building up in the syringe body  38  the piston rod  44  is pushed “in rearward direction” out of the syringe body  38  thus being pressed against the locating bearing  46 . Consequently, a biasing force acts upon the biasing element  36 , the biasing force pushing the the biasing element  36  “in forward direction” thus pressing it against the piston rods  20 , which, in turn, exert a pressure on the medium. 
     By a time-limited release of the bias-induced movement of the biasing element  36  tissue adhesive can be selectedly and dosedly be discharged from the reservoirs  16 . The biasing element  36  is guided in the housing  12  in an axially displaceable manner. A fixing element  56  of a locking device  58  which can engage with and disengage from the biasing element  36  controls the release and/or locking of the biasing element  36 . Said fixing element  56  can be reciprocated transversely to the direction of movement of the biasing element  36 . It encircles, like a ring, a sleeve-type and/or cylindrical part  60  of the biasing element  36 , said part  60  being toothed at two diametrically opposed external face areas such that two rows of teeth and/or toothed racks  62 , 64  are produced. Opposite said rows of teeth and/or toothed racks  62 , 64  fixing projections  66 , 68  of the fixing element  56  are arranged, which alternately, according to the position of the fixing element  56 , can mesh with the toothed rack  62 , 64  located opposite the projections and associated with them. While at the two limit points of the linear movement of the fixing element  56  the biasing element  36  is locked, the biasing element  36  is freely movable when none of the two fixing projections  66 , 68  meshes with the two toothed racks  62 , 64  during the linear movement of the fixing element  56 . This particular feature is explained in detail below. 
     As already stated above, the biasing element  36  and the piston rods  20  are mechanically coupled with each other via the connecting element  32 . Said connecting element  32  is configured as a spindle  70  which is in threaded engagement with the biasing element  36 . At the end facing the piston rods  20  the spindle  70  comprises a connecting and/or receiving part  72  where the plate-type flanges  74  of the piston rods  20  are clampedly supported and which is rotatably supported on the spindle  70 . The spindle  70  passes through an internally threaded extension  76  of the biasing element  36  and comprises a handwheel  78  at its end opposite the receiving part  72 . By manually rotating said handwheel  78  the piston rods  20  can be displaced in the reservoirs  16  when the biasing element  36  is fixed. This function is e.g. required to take in the components of the tissue adhesive contained in ampoules  80  via the three-way valves  24  into the reservoirs  16  in the state of the device shown in FIG.  1 . Further, it is possible to move the piston rods  20  into the reservoirs  16  by reverse rotation of the spindle  70  in order to manually ensure discharge of tissue adhesive. 
     The movement of the fixing element  56  is controlled by a release means  81  having a pin-shaped release element  82  which is reciprocable transversely to the direction of movement of said fixing element  56  when the actuating element  84  configured as an actuating button is actuated. Said actuating button  84  is arranged in the handle of the housing  12  and movable against the force of a spring  86  into said housing  12 . Coaxially to the actuating button  84  a cap  88  is accommodated in said actuating button  84 , said cap  88  carrying the release pin  82 . Said cap  88  is also biased by a readjusting spring  90 , the biasing direction of the cap  88  being identical with the biasing direction of the actuating button  84 . The front end of the release pin  82  averting the cap  88  acts upon a rocker-type swivelling element  92  when the actuating button  84  is actuated, said swivelling element  92  being tiltable and/or capable of being swivelled about a swivelling axis  94  of the housing  12 . Said swivelling element  92  is provided with two swivelling arms  96 , 98  extending linearly on both sides of the swivelling axis  94 . Transversely to the swivelling arms  96 , 98  an extension  100  is arranged which forms one part of a ball-and-socket joint whose other part is configured on the fixing element  56 . The swivelling element  92  is thus mechanically connected with the fixing element  56 . By pivoting the swivelling element  92  the fixing element  56  can thus be reciprocated. 
     The release pin  82  is guided via a double-groove guide  102 . Owing to this guiding the release pin  82  moves both linearly and excurses transversely to this direction of movement when the actuating button  84  is actuated. The double-groove guide  102  comprises two guiding grooves  104 , 106  extending at a slant to the linear movement direction of the release pin, with a carrier projection  108  of the release pin  82  meshing with said guiding grooves  104 , 106 . Due to the double-groove guide  102  the release pin  82  is alternately positioned in two different advance positions, in which the release pin  82  experiences different transverse excursions, when the actuating button  84  is repeatedly pressed. For this purpose the readjusting capability of the release pin  82  transversely excursed in one or both advance positions is utilized. The double-groove guide  102  is operated in a similar way as cartridge writing utensils where the cartridge is moved into an extended position, in which it is locked, and a retracted position by repeatedly pressing an actuating button. 
     Employment of this known double-groove guide  102  in the device  10  offers the advantage that in the case of repeated actuation of the actuating button  84  the rocker-type swivelling element  92  is alternately tilted and/or pivoted in opposite directions such that, due to repeated actuation of the actuating button  84 , the fixing element  56  is reciprocable between its fixing positions by the movement deflection means  110  realized by the swivelling element  92 , in which positions it alternately meshes with one of the two toothed racks  62 , 64  and locks the biasing element  36 . 
     By pressing the actuating button  84  not only the medium discharge but also the gas discharge is controlled in the device  10 . To the gas connection  30  of the connecting head piece  26  a hose  112  is connected which is connected with the gas outlet connection  114  of a gas pressure-controlled valve  116 . Said valve  116  comprises a gas inlet  118  to which a hose  120  is connected which is connected with the Y-type connector  52 . Via the gas inlet  118  the gas to be controlled is supplied to the valve  116  and is allowed to pass to the gas outlet  114  and thus to the connecting head piece  26  in dependence on the position of a control piston  122 . Said valve  116  comprises a valve housing  123  having a first or control chamber  124  and a second or gas passage chamber  126  which is provided with the gas inlet  118  and the gas outlet  114 . The first chamber  124  has a larger cross-section than the second chamber  126 . The control piston  122  effects sealing with its end with the larger cross-section in the first chamber  124  and with its end with the smaller cross-section in the second chamber  126 . Into the first chamber  124  extends a control line  128  connected to a gas inlet  129  of said chamber  124  and connected to the Y-type connector  52 . In the first chamber  124  a vent hole  130  is provided which is closed by a closing element  132  biased into a closed position. Said closing element  132  comprises an actuating arm  134  arranged in the movement path of a carrier element  136  which is connected with the actuating button  84 . 
     In the normal position the valve  116  assumes its closed state in which the control piston  122  is inserted into the second chamber  126  to such an extent that it closes the gas outlet  114 . This state is assumed due to the fact that gas with identical gas pressure acts on both sides of the piston, and a displacement force acting upon the piston  122  occurs in the direction of the second chamber  126  due to the different sizes of the piston front faces. By opening the vent hole  130  the pressure in the first chamber  124  is abruptly reduced. This results in displacement of the control piston  122  into the first chamber  124  and clearing of the gas outlet  114  such that a fluid connection between the gas inlet and the gas outlet  114  is produced. As soon as the vent hole  130  is closed again, the control piston  122  returns into its closed position. To delay this movement and prevent this movement from being carried out abruptly, the control line  128  contains a flow restricting element  138  in the form of a flow restrictor or the like. 
     Now that the basic setup of the device  10  has been described, it can be seen from FIGS. 6 to  9  which intermediate operating stages the device  10  assumes in dependence on the actuation of the actuating button  84 . By pressing the actuating button  84  not only the tissue adhesive discharge but also the gas discharge is controlled. As can be seen in FIG. 6, the valve  116  is operated at the beginning of actuation of the actuating button  84 , wherein the control piston  122  clears the gas outlet  114  as a result of pivoting the closing element (see FIG.  6 ). Now gas flows out of the catheter  28 . At this time the release pin  82  does not yet bear upon the swivelling element  92  and/or just bears upon the swivelling element  92 . Upon further actuation the release pin  82  presses onto the swivelling arm  98  of the swivelling element  92  whereby the latter is pivoted and thus the fixing element  56  is moved out of the locking position assumed before and via a temporarily assumed release position into the second locking position. For the duration during which none of the fixing projections  66 , 68  of the fixing element  56  meshes with the toothed racks  62 , 64  the biasing element  36  can move in forward direction thus moving the piston rods  20  into the reservoirs  16 . Consequently, the tissue adhesive is discharged via the catheter  28  (see FIGS.  6  and  7 ). When the actuating button  84  is fully pushed (see FIG.  8 ), the closing element  132  closes the vent hole  130  of the valve  116 . Thus the control piston  122  moves in a time-delayed manner back into the second chamber  126  and closes the gas outlet  114  when it has assumed its final position. This means that for a short time after the discharge of tissue adhesive gas flows out of the catheter  28 . If a tissue adhesive droplet forms at the end of the catheter  28 , this droplet is atomized by the gas flow. 
     After release of the actuating button  84  the situation shown in FIG. 9 occurs. As can be seen, the release pin  82  is in a position further inside the housing  12  as compared with the position shown in FIG. 1, wherein its free end is located opposite the swivelling arm  96  upon which the release pin  82  has not acted during the previous advance movement. This means that during the next actuation of the actuating button  84  the release pin  82  acts upon the swivelling arm  96  which results in the fixing element  56  being moved from the position shown in FIG. 9 into the position shown in FIG.  1 . 
     FIGS. 10 and 11 show, on an enlarged scale, the cooperation and the configuration of the fixing element  56  and the cylindrical part  60  of the biasing element  36 . The fixing element  56  encircles, like a ring, the part  60  of the biasing element  36 , and its fixing projections  66 , 68  alternately, according to the displacement position, mesh with one of the two toothed racks  62 , 64 . 
     As shown in FIGS. 13,  17 ,  18 ,  20 ,  22  and  24 , the two readjusting springs  86 , 90  set the elements (actuating button  84  and cap  88 ) coupled with said readjusting springs  86 , 90  into an extended position. Since, due to the double-groove guide  102  with the guiding grooves  104 , 106  arranged one behind the other as seen in the direction of movement of the release pin  82 , the position of the release pin  82  differs, but, irrespective of this, the actuating button  84  is to be returned always into one and the same initial position after having been released, the second spring  86  is required, besides the first spring  90  acting upon the cap  88 , for moving the actuating button  84  back. If this double spring arrangement did not exist, the actuating button  84 , in the state shown in FIG. 18, would not be fully moved back. This is however necessary, on the one hand for reasons of an improved haptics and handling of the device  10 , and on the other hand due to actuation of the closing element  132  of the valve  116  by means of the pushbutton  84 . 
     FIGS. 12 to  25  further show that the release pin  82  is moved against the plate  140  via an integrally formed spring arm  139 , the plate  140  comprising the two guiding grooves  104 , 106 . This pressing is appropriate to ensure, irrespec tive of any vibrations acting upon the release pin  82 , that the carrier projection  108  of the release pin  82  remains in engagement with one of the two guiding grooves  104 , 106 . 
     Finally, FIGS. 12 to  25  show the advance and pivoting positions of the release pin  82  in dependence on the position of the actuating button  84  and its actuation sequence. The following description is based on the situation shown in FIG.  13 . In this position the carrier projection  108  of the release pin  82  is in the first guiding groove  106  relative to the advance movement of the release pin  82  towards the swivelling element  110 . When the actuating button  84  is acutated the release pin  82  is forcedly moved downwards (relative to the representation in the FIGS.)(as shown by the dot-dash line in FIG.  13 ). When the carrier projection  108  has reached at the end of the guiding groove  106 , the release pin  82  is moved away from the plate  140 , since the carrier projection  108  comprises a bevelled face  142  at its free front end, said bevelled face  142  causing this extending movement of the release pin  82  when the carrier projection  108  has reached the end of the guiding groove  106  and a force continues to act upon the actuating button  84 . To prevent the release pin  82  pivoted into this position from moving back into its linear position shown in FIG. 13 due to its readjusting capability when the carrier projection  108  is moved out of the guiding groove  106 , the plate  140  comprises a graduated portion  144  with a guiding edge  146  along which the carrier projection  108  slides up to the second guiding groove  104  as long as it is outside the guiding groove  106  (see the intermediate positions shown in FIGS. 15 to  17 ). The guiding edge  146  thus connects the ends, shown in the lower section of the drawing plane, of the two slanting guiding grooves  106 , 104  of the double-groove guide  102 . 
     In the position shown in FIG. 17 the carrier projection  108  is located in the guiding groove  104  facing the swivelling element  110 . Further, the guiding pin  82  acts upon the swivelling element  110  and rotates said element. When the actuating button  84  has been released, the guiding pin  82  is moved back by the readjusting spring  90  until the carrier projection  108  bears upon the end of the guiding groove  104  facing the actuating button  84  (see FIGS.  18  and  19 ). If, proceeding from this position, the actuating button  84  is pushed again (see FIGS.  20  and  21 ), the release pin  82  is moved again in forward direction towards the swivelling element  110 . Meshing of the carrier projection  108  with the guiding groove  104  would result in an excursion movement of the release pin  82  transverse to the direction of its linear movement. The guiding groove  104  comprises however a trapping recess  150  in its bend area  148  (see FIG. 17) into which trapping recess  150  the carrier projection  108  is inserted (see FIG.  21 ). Thus the carrier projection  108  does not follow the further slanting course of the guiding groove  104  but rather moves out of the guiding groove  104  via the bevelled face  142 , more precisely, out of the trapping recess  150 . Thus the release pin  82  moves essentially linearly in forward direction, has however a certain readjusting capability due to a slight excursion. This readjusting capability has the effect that the release pin  82  linearly aligns itself, and its carrier projection  108  is placed into a position above the guiding groove  104  (see FIG.  22 ). Besides the fact that the release pin  82  acts upon the swivelling element  110  as the release pin  82  continues to move in forward direction (see FIGS.  22 , 23 ), the movement of the carrier projection  108  up to the area above the guiding groove  104  has the effect that the carrier projection  108  laterally slides past the upper end of the guiding groove  104  when the pushbutton  84  is released (see FIG. 24) in order to mesh with the upper end of the guiding groove  106  (see FIGS.  24  and  25 ). At this point the same movements as described with reference to FIG. 12 are started again when the pushbutton  84  is actuated the next time. 
     Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the apparatus without departing from the spirit and scope of the invention, as defined the appended claims.