in the description below , identical reference numbers designate identical parts , unless otherwise stated . features , functions and / or structures of different embodiments can be combined with one another . fig1 shows a schematic representation of an insertion device 1 , with a housing 2 , with a housing aperture 3 on the underside , with an infusion set 30 which is held releasably and in an axially displaceable manner in the housing 2 , and with a corresponding displacement mechanism 4 . the displacement mechanism 4 has four interconnected leg levers 5 , 6 , 7 , 8 . the two upper leg levers 5 , 6 are mounted rotatably in the housing 2 at their bearing ends 52 , 62 by way of their own bearing axles 51 , 61 . in addition , the bearing ends 52 , 62 mesh with one another via teeth ( fig2 ), comparable to a compass as described in de 2 , 357 , 745 . both upper leg levers 5 , 6 are connected via connection axles 71 , 81 to the lower leg levers 7 , 8 , which in turn are mounted by way of bearing axles 91 , 92 on a receiving element 9 for the infusion set 30 . by means of this connection of the individual leg levers 5 , 6 , 7 , 8 to one another and to the housing 2 or receiving element 9 , a pivoting of the upper leg levers 5 , 6 with respect to one another results in an axial displacement of the receiving element 9 and , consequently , of the infusion set 30 toward the housing aperture 3 . upon maximum pivoting of the leg levers 5 , 6 with respect to one another , the underside 32 of the infusion set lies slightly outside the housing aperture 3 . the displacement mechanism also has an elastic element or member 13 , for example a spring , which in fig1 is arranged between the upper leg levers 5 , 6 and causes a pivoting movement of the upper leg levers 5 , 6 with respect to one another . it would be likewise possible to arrange the spring 13 between housing 2 and at least one leg lever 5 , 6 , above the connection axles 71 and 81 between the upper and lower leg levers . by way of a release device , for example , a release button 10 , the displacement mechanism is freed from a tensioned to a non - tensioned position . an infusion set 30 usually comprises a head 31 , a holding element 34 arranged thereon , an adhesive underside 32 , and a cannula 33 for penetrating the skin . depending on the design of the cannula 33 , either from easily bendable material , for example teflon , or harder material , for example steel , the cannula 33 can itself penetrate the skin or may require an additional insertion cannula ( not indicated ). fitted on the catheter head is an infusion catheter ( not shown ) which creates a fluidic connection between the cannula 33 and an administration device ( not shown ), for example an insulin pump . in use , an infusion set 30 is arranged on the receiving element 9 by means of a holding element 34 , and , by moving the receiving element 9 away from the housing aperture 3 , the displacement mechanism 4 is brought from the non - tensioned to the tensioned position . the housing 2 of the insertion device 1 is pressed with the housing aperture 3 onto the skin . by actuating the release button 10 , a movement of the upper leg levers 5 , 6 with respect to one another and , consequently , a movement of the receiving element 9 and of the infusion set 30 in the direction of the housing aperture 3 is instigated . the displacement mechanism 4 forces the cannula 33 under the skin and at the same time forces the adhesive underside 32 onto the surface of the skin . to allow the catheter head 31 to be removed from the insertion device 1 in a way which is as painless as possible , actuation of an ejector device 15 releases the holding element 34 from the receiving element 9 . in the simplest case , the holding element 34 is held in the receiving element 9 by means of frictional engagement , such that the ejection takes place by means of light axial pressure being exerted on the holding element 34 via the ejector device 15 , for example in the form of a drive rod . fig2 shows a modified insertion device . here , the displacement mechanism 4 also has four interconnected leg levers 5 , 6 , 7 , 8 , the two upper leg levers 5 , 6 being mounted in the housing 2 by way of bearing axles 51 , 61 at their bearing ends 52 , 62 , and meshing with one another via teeth . both upper leg levers 5 , 6 are connected by connection axles 71 , 81 to the lower leg levers 7 , 8 , which in turn are mounted in a receiving element 9 for the infusion set 30 by way of bearing axles 91 , 92 . in this embodiment , the ends of the lower leg levers 7 , 8 arranged around these bearing axles 91 , 92 also mesh with one another via teeth ( not shown ) in order to ensure that the receiving element 9 cannot buckle to the side . such buckling would have the effect that , during the insertion process , the cannula 33 would not move perpendicular to the surface of the skin . actuation of the release button 10 leads to a sideward movement of a locking lug 11 , arranged on the receiving element 9 , from a holding fixture 12 arranged in the housing 2 and , consequently , to the release of the displacement mechanism 4 from a tensioned to a non - tensioned state . in use , movement of grip elements 17 a , 17 b in the direction of the release button 10 tensions the displacement mechanism 4 and engages the locking lug 11 in the holding fixture 12 . actuation of the release button 10 leads to a sideward movement of the locking lug 11 and , consequently , to release from the holding fixture 12 and thus to release of the displacement mechanism 4 from a tensioned to a non - tensioned position . when the cannula 33 is arranged under the skin , renewed actuation of the release button 10 causes a slight axial movement of the ejector device 15 and thus , via cams ( not shown ), an axial movement to the infusion set 30 held by frictional engagement in the receiving element 9 . this movement suffices to eject the infusion set 30 from the receiving element 9 . fig3 to 7 show a second exemplary insertion device according to the present invention which likewise is based on the principle of a lever mechanism . fig3 shows the insertion device without infusion set in the tensioned state . fig3 indicates a spring 213 which is visible at its ends 213 a , 213 b . one end 213 a bears on an abutment 214 which is connected to the housing 202 a in a positionally fixed manner . the other end of the leg spring 213 presses against the leg lever 205 and seeks to press this downward in fig3 . the spring is prevented from doing this by the latch 211 which , with a hook , is engaged on a rib 212 at the upper end of the housing . the rib 212 is connected to the housing 202 in a positionally fixed manner . the leg lever 205 is connected to another leg lever 208 , arranged below it , via a rotary connection member ( axle ) 241 which ensures a rotation of the leg levers 205 and 208 about the common axle 241 . a further rotary connection member 242 is arranged at the upper end of the leg lever 205 . the rotation axle of the connection member 242 is positionally fixed , in contrast to the rotation axle 241 . arranged on the axle of the connection member 242 is a toothed wheel 243 which rotates together with the upper end of the leg lever 205 . the toothed wheel 243 meshes with a toothed wheel 244 which rotates about a rotary connection member 245 or an axle 245 . this toothed wheel 244 is connected to the upper end of the leg lever 206 in such a way that it co - rotates with the latter . thus , a rotation movement of the leg lever 205 about the axle 242 causes , via the meshing toothed wheels , a corresponding rotation movement of the leg lever 206 in the opposite direction about the axle 245 . a second leg spring is provided whose one leg is likewise supported on the housing , while the other one forces the leg lever 206 downward . a rotation movement about the axle 245 caused by this is likewise transmitted via the toothed wheels 244 and 243 to the leg lever 205 . the leg lever 205 is connected via the rotary connection member 241 to the leg lever 208 , which in turn is connected via a rotary connection member 247 to a hammer head or plunger 244 which serves as a drive endpiece . correspondingly , the leg lever 207 is connected to the hammer head 224 via a rotary connection member 248 . grip elements 217 a and 217 b are connected fixedly to the hammer head 224 . the hammer head 224 extends through elongate slits 218 located on both sides of the housing , and specifically in a manner free of contact , so as to have no friction losses . in the position shown in fig3 , the hammer head is at its uppermost end . a recess or receiving element 235 serves to receive an infusion set , as can be seen in fig4 . the housing is designed in two parts , namely with parts 202 a and 202 b , and the part 202 b can be pushed downward , as will be discussed later in connection with fig5 . as has already been mentioned , an infusion set 230 is shown which comprises the following components : head 231 , main part 234 , protective sleeve for the cannula 233 , and what is called a liner or adhesive plaster 232 . the infusion set 232 is fitted on the receiving element 235 which is now concealed in fig4 and which is connected to the rear wall 236 of the housing . as can be seen from fig4 , a gap 237 is present between the infusion set 230 and the hammer head 234 when the latter is in the locked state , that is to say the locking lug or latch 211 is locked , as has already been discussed with reference to fig3 . fig5 now shows the insertion device in a ready for use state . the insertion device is charged or loaded with the infusion set . the protective sleeve 233 has been removed , so that the cannula 237 now projects freely . the lower housing half 202 b has been drawn out and thus surrounds and protects the exposed cannula 237 . the lower ends 202 c of the housing 202 b may be generally flat to ensure a good placement of the housing on the skin . fig6 shows the insertion device after the release button 210 has been actuated and the cannula has penetrated into the skin . as will be seen , the liner 232 protrudes below the housing , as of course does the cannula or needle 237 , such that the latter can penetrate into the skin unimpeded by the housing . the leg levers 205 and 206 have been forced downward by the relaxing of the leg spring 213 and by another leg spring ( not shown ) after the locking lug 211 has been released from the rib 212 by way of the release button 210 . the leg levers 205 , 206 , 207 and 208 are now in the extended state and have turned about the respective connection members . by this means , the hammer head 224 has been driven down in its drive direction . by virtue of the sufficiently widely dimensioned gap 218 , the hammer head has also been moved forward without friction and without contact in this gap , and the grip elements 217 a and 217 b are now located in their lower end state . while the hammer head has been driven forward in the downward direction , it has struck against the upper end 239 of the infusion set 230 and thus released it from the receiving element 235 in which the infusion set has been held by form fit , force fit and / or friction . as a result of inertia , from this point onward , the infusion set 230 flies in the same direction as the hammer head 224 moves , and the cannula 237 thus pierces the skin . the infusion set thus moves in a free flight and unguided . however , optimal puncturing results were able to be achieved , since friction losses resulting from guidance of the infusion set have been avoided . fig7 now shows the insertion device in a state before it is tensioned again and in a state in which no infusion set has yet been introduced . by pressing the grip elements 217 a and 217 b up toward the spring 213 , the hammer head 224 is brought back up to its charged position . the holding fixture for the infusion set on the housing can be configured in different ways . for example , the upper end of the infusion set can be held with force - fit between two receiving elements 235 serving as clamping fixtures . one clamping fixture 235 is mounted on one wall of the housing 202 a , and the other lies opposite it . the distance between the clamping fixtures is greater than the width of the hammer head 224 , so that the latter can pass without contact between two opposite clamping fixtures 235 and can carry the infusion set with it and release it from the clamping fixture . as an alternative to clamping , the receiving element 235 can also be designed such that it has , for example , extensions which point downward , and the infusion set is then fitted from below onto these extensions , the infusion set having corresponding depressions so as to produce , for example by means of frictional engagement , the plug connection between infusion set and extension . the extension and the depression are once again arranged such that the hammer head , during its movement in the drive direction , can pass without making contact with it and then carries the infusion set with it . further to the above description , it will be noted that the leg springs may be mounted about the axles 242 and 245 . for the case of frictional or form - fit engagement with the infusion set to be introduced , the receiving elements 235 are provided with elastic means which acts perpendicularly or transversely with respect to the drive direction , and in which two elastic means lying opposite one another clamp the infusion set securely , this also being able to be achieved , of course , with a single elastic means . as will be seen from fig8 b , the receiving elements 235 press laterally against the infusion set so as to securely clamp it . the pressing action is effected by means of the elastic elements 251 which , for example , are helical springs . fig8 c shows a plan view of fig8 b . if the hammer head 224 now strikes against the upper end of the infusion set 230 , the receiving elements 235 are forced back counter to the spring force of the springs 251 , and the infusion set flies downward , freely accelerated by the force of the impacting hammer . fig8 b is a sectional view along the line a - a in fig8 a . in one embodiment , the receiving elements 235 are thrust pins which , upon insertion of the infusion set , produce an audible click in order to show the patient that the infusion set has been correctly inserted . abutments 252 and 253 are also arranged above the infusion set to obtain a correct position of the infusion set . the distance “ d 1 ” between hammer head and infusion set is in the range of approximately 0 to 10 mm . the protective sleeve ( needle guard ) and the protective paper may be removed after the infusion set has been secured in its starting position , that is to say in the tensioned position shown in fig8 . by virtue of the secure clamping of the infusion set and locking by the locking lug 211 , this can be done without danger . the insertion device is now ready to apply the infusion set . for this purpose , the infusion set is placed onto the skin at the intended site . to release it , all that has to be done is to actuate the button 210 . by this means , the locking lug ( snap - in hook ) is deflected and the snap - fit connection thus released . the pretensioned mechanism is then accelerated downward , and the hammer head strikes against the infusion set after a free flight ( without contact with the housing ). the hammer head exerts on the infusion set a downward vertical force component which transmits laterally to the receiving elements 235 ( thrust pins ). by this means , the springs are compressed , leading to release of the infusion set . the infusion set is now applied into the body by the spring force of the pretensioned levers . the distance “ d 2 ” shown in fig9 a between hammer head and infusion set after release does not have to be defined . depending on the curvature of the skin at the application site , the infusion set is in contact or not in contact with the hammer . after the puncturing procedure , the insertion device can be removed from the application site and the application procedure is completed . in a further variant not shown in the figures , but which can be understood therefrom and from this description , the infusion set is not secured on the housing in such a way as to be struck off it by the hammer head , and instead the infusion set is attached to the hammer head itself . this means that the upper end of the infusion set is brought into connection with the lower end of the hammer head . this can be done , for example , by adhesive bonding , frictional engagement or a form - fit . in some cases , the infusion set can be plugged onto or into the hammer head . in this case , the hammer head can , for example , have an extension which engages into a corresponding recess in the infusion set , for example with an exact fit , to hold the infusion set by frictional engagement . of course , this can also be reversed , that is to say the infusion set has an extension and the hammer head has a corresponding recess . the infusion set can also engage round the hammer head with a clamping action so as to be secured thereon , or vice versa . care is taken to ensure that , during the movement in the drive direction , neither the infusion set nor the hammer head comes into contact with the housing , so as to avoid unnecessary friction losses upon conversion of the potential energy of the drive means into the kinetic energy of the infusion set . this allows the infusion device to be made compact , without excessively large drive means . fig9 also illustrates the principle of the present invention , with identical reference numbers designating the same parts as in the embodiment described above . the variant of the second embodiment described with reference to fig8 and 9 is similar to this . referring to fig9 , a lateral introduction of the infusion set into the inserter or insertion device is described . the insertion set 230 is pushed laterally in the direction e 1 into the insertion device . the distance between the hammer head 224 and the upper end 238 of the infusion set is designated by “ d 1 ”. this distance can be 0 or greater than 0 as in the previous embodiment . a guide 250 serves as abutment surface for the infusion set in order to orient the latter correctly with respect to the hammer 224 . correspondingly , in the second embodiment , the rear wall 236 shown in fig4 can be designed to guide the infusion set when it is introduced into the insertion device . the lateral introduction of the infusion set can also be provided in the other embodiments . for example , in the sixth embodiment ( fig1 to 16 ), a gap 612 at the side ( fig1 a ) is provided for this purpose . fig1 shows a further embodiment of the present invention , in which an elastic means serves both as a guide for the drive endpiece and also as a drive mechanism . in the embodiment shown in fig1 , the elastic means is formed from an elastic material and assumes an elongate shape , with constant cross section in the longitudinal direction , so that , in the released state , its distance from the housing is constant along the entire longitudinal extent . the elastic means may be formed from any suitable elastic material , for example , a foam , rubber , etc . fig1 a shows the infusion set which , in fig1 b , is inserted into the receiving element 335 . the receiving element serves to hold the infusion set , for example by frictional engagement or with a force fit . the grips 317 a and 317 b extend in a longitudinal slit of the housing and are used for charging the insertion device , by the elastic means 313 being brought from a released state ( fig1 b ) to a tensioned state ( fig1 c ). in this process , the cam 311 engages in the release button 312 . the ejector 352 is entrained in this movement . if the release button 312 is now moved away from the cam 311 in fig1 c , the energy stored in the elastic means 313 discharges and drives the drive endpiece 335 , at the same time designed as receiving element , in the drive direction . after the infusion set has thus been applied to the skin , the ejector 352 serves to release the infusion set from the receiving element 335 . fig1 shows another embodiment of the present invention in which a drive endpiece is designed in the form of a punch or an inverted t . the drive endpiece has a lower end 424 a onto which an infusion set can be fitted , or which is designed to strike the latter out of a holding fixture which , for example , is secured on a housing wall . the drive endpiece also has a part 424 b which extends in the drive direction and which is here referred to as connecting rod . pivot bearings 448 and 447 are mounted on this connecting rod and each serve as rotary connection members for levers 408 , 407 and 417 , 418 , respectively . the rotary connection members 421 , 422 , 423 and 425 are not fixedly connected to the connecting rod 424 , but only via the levers 407 , 408 , 417 and 418 . these rotary connection members are in turn connected in each case via leg levers 405 , 406 , 415 and 416 to rotary connection members or pivot bearings 401 , 402 , 411 , 412 on the housing wall . the embodiment shown permits guidance of the connection endpiece along a lemniscate curve and may , therefore , also be referred to as a lemniscate guide . the connecting rod is guided at least substantially vertically by this . the elastic tensioning means and the locking mechanism and release mechanism can be designed analogously to the other described embodiments . the elastic means can be connected to the connecting rod and / or to one or more of the leg levers so as to pretension these in such a way that the connection endpiece is accelerated downward when the tension of the elastic means is released . fig1 shows a further embodiment of the invention . a leg lever 505 is attached at one end on the housing wall 502 via a rotary connection member 542 . an infusion set 530 is secured at the opposite end of the leg lever . the leg lever can be tensioned against the housing wall 502 via a spring 513 as is shown in fig1 b . if a locking mechanism ( not shown ) is released , the leg lever 505 is forced downward by the spring 513 , as is shown in fig1 a . if a free end of the leg lever strikes against an abutment 503 , the infusion set 530 can be released , for example from a frictional connection , and , after a short free flight , can penetrate the skin . instead of the abutment , it is of course also possible to provide an ejector mechanism with which the infusion set can be released from the insertion device after it has penetrated the skin . alternatively , the infusion set can also be struck out of a holding fixture by the leg lever 505 , as has been described in other embodiments . fig1 to 16 show another embodiment of the present invention . fig1 a shows the insertion device in the tensioned state , that is to say the charging grip 601 is drawn upward . the release mechanism 602 is located to the left and right of the charging grip . these are pressed inward for release . the housing is designated by 603 and surrounds a drive endpiece 604 , which can be seen in fig1 b . an elastomer part 605 is located at the lower end of the housing 603 and may be suitably connected , including integrally connected , to the latter . this elastomer part 605 is guided round a sleeve 606 at the lower end of the insertion device , as can be seen from fig1 b . the elastomer part bears on the lower inside wall of the sleeve 606 at a location designated by 605 a . from there , it branches upward in the form of a band 605 b . fig1 b also shows the tensioned state . fig1 shows the non - tensioned state in which the charging grip 601 has moved downward after the release mechanisms 602 have been actuated . a needle tip 630 can be seen at the bottom protruding downward from the insertion device . fig1 b corresponds to fig1 a . fig1 c shows the state of fig1 a with the infusion needle 630 and the liner or plaster 631 . the drive endpiece 604 is located at the lower end of its path of movement . the lowermost end of the drive endpiece 604 lies at least approximately in the plane of the lower end of the elastomer part 605 . as can be seen from fig1 c , there is a space between the lower end 605 of the elastomer part and the drive endpiece 604 . fig1 a shows , in cross section , the non - tensioned state from fig1 a . the infusion set 632 is mounted in the drive endpiece 604 . hooks 610 are engaged with the drive endpiece 604 and define the deepest position of the path of movement of the drive endpiece . as will be seen from fig1 b , the band 605 b of the elastomer part is guided round a top end of the drive endpiece , such that the band is stretched when the drive endpiece is moved upward . the upward movement is effected with the aid of the charging grip 601 . at its lower end , this charging grip has two hooks 601 a and 601 b which are locked in engagement with a correspondingly designed projection 604 a of the drive endpiece . this locked engagement can be released by the release mechanisms 602 because , when the charging grip 601 is drawn out , they act on extensions 601 c which can be seen in fig1 a . fig1 c shows the tensioned state in cross section . the band 605 b is tensioned , and the insertion device is ready for application , the drive endpiece 604 being moved downward until extensions 604 a strike against the hook - shaped ends 610 a . fig1 shows component parts of the insertion device of fig1 to 15 . here , 606 indicates the sleeve , 601 the charging grip , 602 the release mechanisms , 636 a guard for the needle , 604 the drive endpiece , 605 the elastomer part , and 603 the housing . embodiments of the present invention , including preferred embodiments , have been presented for the purpose of illustration and description . they are not intended to be exhaustive or to limit the invention to the precise forms and steps disclosed . obvious modifications or variations are possible in light of the above teachings . the embodiments were chosen and described to provide the best illustration of the principles of the invention and the practical application thereof , and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the use contemplated . all such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth they are fairly , legally , and equitably entitled .
an insertion device for infusion sets , comprising a housing for enclosing an infusion set , a drive device for displacing the infusion set for insertion , wherein a portion of the drive device moves in an insertion direction , the movement being substantially friction - free relative to the housing .