Centrifuge rotor mounted on drive shaft

Abstract

A rotor 10 of a centrifuge 100, having a receiving chamber 18 for samples to be centrifuged, a concentrically mounted seat 20 which is associated with a support 106 of a drive shaft 104 of said centrifuge 100, a lid 40 which limits the receiving chamber 18 at the top, which is mounted concentrically relative to the rotor and which has, on its side remote from the receiving chamber 18, a handle 44 for carrying the rotor and the lid 40, and a locking mechanism 50, 34b of lid 40 and rotor, which locking mechanism 50, 34b comprises a locking element 50 which can be moved between a locking position and an unlocking position thereof. In accordance with the invention, part of the handle 44 is adapted to be movable and is operatively connected to a retaining element 48b, 48c, which retaining element 48b, 48c can be moved, by the handle 44, between a first position which prevents actuation of the locking element 50, and a second position which releases the locking element 50.

Claims

1. A rotor (10) of a centrifuge (100), comprising: a receiving chamber (18) for samples to be centrifuged; said receiving chamber (18) includes a top; said centrifuge includes a drive shaft (104); said drive shaft (104) includes a support (106) mounted thereon; a concentric seat (20) concentrically mounted on said support (106) of said drive shaft (104) of said centrifuge (100); a lid (40); said lid includes a remote side facing away from said receiving chamber (18); said lid (40) limits said receiving chamber (18) at said top when said lid (40) is mounted concentrically with said rotor in said receiving chamber (18); a blocking device (22, 24, 26) fixing said rotor in position relative to said drive shaft (104) of said centrifuge (100); an activating element (74, 36) mounted in said lid (40) for activating said blocking device (22, 24, 26); said activating element (74) includes a far end protruding outside of said lid (40) when said lid (40) is mounted concentrically in said receiving chamber; said blocking device (22, 24, 26) includes a blocking unit (26) which is movable between a blocking position and a releasing position by said activating element (74, 36); said activating element (74, 36) releasing said blocking device from said blocking position to said releasing position, said far end of said activating element (74, 36) includes a pushbutton (82) thereon; a handle (44) resides on said remote side of said lid facing away from said receiving chamber (18) for carrying said rotor and said lid (40); said pushbutton (82) is outside said handle (44) when said blocking unit (26) is in said blocking position; said lid includes a locking mechanism (50, 34b) for locking said lid (40) and said rotor; said locking mechanism (50, 34b) comprising: a locking element (50) movable between a locking position and an unlocking position thereof (50); and, a retaining element (48b, 48c); a part of said handle (44) is adapted to be movable and is operatively connected to said retaining element (48b, 48c); and, said retaining element (48b, 48c) movable by said handle between a first position which prevents actuation of said locking element (50) and a second position which releases said locking element (50).

2. A centrifuge (100), comprising: a rotor (10); a drive; a drive shaft (104); said drive shaft (104) includes a free end; a support (106) mounted on said free end of said drive shaft (104); said rotor includes: a receiving chamber (18) for samples to be centrifuged; said receiving chamber (18) includes a top; a concentric seat (20); said concentric seat (20) of said rotor is mounted on said support (106) mounted on said free end of said drive shaft (104) of said centrifuge 100); a lid (40); said lid (40) limits said receiving chamber (18) at said top, said lid (40) is mounted concentrically relative to said rotor; a blocking device (22, 24, 26) having a blocking body (22) interacting with a blocking unit (26) fixing said rotor (10) to said drive shaft (104); said blocking body (22) is mounted on said seat (20) of said rotor and engages said support (106) through a recess (110) in said support (106) and, in a locking position, said blocking body (22) is embraced by said blocking unit (26) and an outer circumference of said blocking unit (26) embracing said blocking body (22) is larger than an inner circumference of said recess (110); a handle (44) on a remote side of said lid from said receiving chamber (18) for carrying said rotor and said lid (40); said lid includes a locking mechanism (50, 34b) for locking said lid (40) and said rotor; said locking mechanism (50, 34b) comprising: a locking element (50) movable between a locking position and an unlocking position thereof (50); a retaining element (48b, 48c); a part of said handle (44) is adapted to be movable and is operatively connected to said retaining element (48b, 48c); and, said retaining element (48b, 48c) is movable between a first position which prevents actuation of said locking element (50) and a second position which releases said locking element (50).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings,

(2) FIG. 1 is a lateral sectional view of a rotor of the invention with the lid in place, in which the locking of the lid has been activated (section through the rotor axis);

(3) FIG. 2a is a lateral sectional view of the lid of FIG. 1, in which locking has been activated and blocking has been deactivated;

(4) FIG. 2b is a lateral sectional view of the lid, in which both locking and blocking have been activated;

(5) FIG. 2c is a lateral sectional view of the lid, in which both locking and blocking have been deactivated;

(6) FIG. 3 is an exploded lateral sectional view of the rotor of FIG. 1 with the lid removed, and of the rotor receiving chamber of the drive shaft of a centrifuge;

(7) FIG. 3a is an enlarged view of a detail marked III a in FIG. 3;

(8) FIG. 3b is a perspective view of a blocking element;

(9) FIG. 4 is a perspective sectional view of the rotor, similar to the view of FIG. 1;

(10) FIG. 5a is a lateral sectional view of the lid with activated locking and deactivated cover according to an alternative embodiment;

(11) FIG. 5b is a lateral sectional view of the lid with activated locking and activated cover according to said alternative embodiment;

(12) FIG. 5c is a lateral sectional view of the lid with deactivated locking and deactivated cover according to said alternative embodiment; and

(13) FIG. 6 is a lateral sectional view of a centrifuge according to the invention.

DESCRIPTION OF THE INVENTION

(14) FIG. 1 is a lateral sectional view of a rotor 10 according to the invention with the lid 40 in place and activated locking of the lid 40.

(15) The rotor 10 has the basic shape of a truncated cone which tapers toward the top. Provided in a rotor head 12 in a conventional manner and uniformly spaced from each other are receiving units 14 for sample containers 16. The longitudinal extension of the receiving units 14 is parallel to the lateral surface 12a of the rotor head 12. The view of FIG. 1 shows four sample containers 16 inserted in the receiving units 14. Sealing caps 16a of the sample containers 16 protrude from the respective receiving units 14 into a receiving chamber 18 of the rotor 10.

(16) Mounted concentrically in a bottom 12b of the rotor head 12 is a rotor seat 20 which is associated with the support 106 of the centrifuge 100. The rotor seat 20 has a frusto-conical first portion 20a which tapers in a removal direction E and which is adjoined in an axial direction by a cylindrical second portion 20b. The upper boundary of the rotor seat 20 is a boundary surface 20c which is perpendicular to the rotor axis R. Concentrically mounted on this boundary surface 20c is a locking ball 22 which faces the support 106 of the centrifuge 100 and extends away from the boundary surface 20c along the rotor axis R and whose function will be explained in more detail below with reference to FIGS. 3, 3a and 3b.

(17) Above the locking ball 22, a rotor pin 34 is mounted within the receiving chamber 18 which is concentric relative to the rotor axis R and which has an external contour 34a that conically tapers towards its free end. The rotor pin 34 is shown in more detail in FIG. 3, and in particular in the enlarged detail of FIG. 3a.

(18) Placed on the rotor 10 is a lid 40 which seals the receiving chamber 18 from the outside in an aerosol-tight manner. Mounted concentrically relative to the lid 40 is a handle 44 which is used to place the lid 40 on the rotor 10 and to remove the lid 40 from the rotor 10. Part of the handle 44 is inserted in a blind-hole shaped recess 42 of the lid 40 and firmly connected to the latter in a conventional manner. The recess 42 has an aperture 42a which is concentric to the rotor axis R and provided in the cylindrical bottom of the recess, and through which the free end of the rotor pin 34 engages the handle 44.

(19) For the sake of clarity, the handle 44 is shown in enlarged detail in FIGS. 2a, 2b and 2c. The handle 44 has a cylindrical bearing body 46 which has a wall 48 mounted on its outer wall for movement in an axial direction. Within the bearing body 46, two tilt levers 50 are mounted opposite each other relative to the rotor axis R. The longitudinal extension of the tilt levers 50 is essentially aligned axially. Provided approximately in the middle of the cross-section of the tilt levers 50 is a thickened portion 52 which points towards the bearing body 46 and which is rounded. A strut 54 each (not shown for reasons of clarity) runs through these thickened portions 52 about which the tilt levers 50 can be tilted. The strut 54, together with its associated recess in the thickened portion 52, thus forms a tilt joint for the tilt levers with respect to the bearing body 46 and the wall 48 which completely surrounds at least parts of the latter. On the upper end of the tilt lever 50, there is an actuating member 56 which faces in a direction away from the rotor axis R. Moreover, each tilt lever 50 tapers in cross-section towards the upper end. Each tilt lever 50 also tapers in cross-section towards the lower end, on which a latching element 58 each pointing towards the rotor axis R is mounted on the tilt lever 50.

(20) The actuating members 56 each have an associated recess 46a in the bearing body 46 and a recess 48a in the wall 48 through which part of the actuating members 56 protrudes laterally from the handle 44.

(21) At the upper end of each tilt lever 50 is a recess 60 each which is engaged by an end of a spring 62, more specifically a leaf spring, which is arranged along the bearing body 46 of the handle 44. The ends of the springs 62 which are remote from the recesses 60 are clamped onto the bearing body 46 and radially preloaded toward the outside. The spring 62 will thus urge the upper ends of the tilt levers 50 radially outwards, if, as shown in FIG. 2a, no force is applied manually from the outside, and into abutment on the bearing body 46, and the actuating members 56 will protrude laterally from the handle 44 to a maximum extent. At the same time, the tilt levers 50 will be tilted about the struts 54 in such a way that the lower ends will be spaced from the bearing body 46. The latching elements 58 will latch into engagement with a circumferential groove 35b made in the external contour 34a of the rotor pin 34. In this position of the tilt levers 50 as shown in FIG. 2a, the rotor 10 and the lid 40 are locked together.

(22) FIG. 2b is a view of the handle 44 with the tilt levers 50 in the same position as in the view of FIG. 2a, i.e. the locking position. Here, the wall 48 of the handle 44 has been moved axially relative to the bearing body 46 in the removal direction E. This relative change in position of the wall 48 with respect to the bearing body 46 is brought about by an operator grasping the handle 44 and lifting it without releasing the locking of lid 40 to rotor 10, rather than applying force to the actuating members 56 so as to tilt the tilt levers 50 and release the latching elements 58 from the groove 34b made in the external contour 34a of the rotor pin 34.

(23) As the wall 48 changes position, a projection 48b which is located on the end of the wall 48 that points in the direction of the receiving chamber 18, and which extends in the direction of the rotor axis R and which reaches through a recess (not shown) in the bearing body 46 will also be entrained. Lifting the wall 48 in the removal direction E will cause the projection 48b to abut on the tilt lever 50 in the area between the thickened portion 52 and the latching element 58. This will block the tilt lever 50 so as to prevent it from tilting about the strut, and the latching element 58 will thus be secured within the groove 34b. The locking between the rotor 10 and the lid 40 cannot be released in this blocking position.

(24) A spring not shown here for the sake of clarity applies a force to the wall 48, which force acts against the removal direction E. As soon as the operator sets down the rotor 10 or places it inside a centrifuge 100, which will neutralize the weight force acting on the handle 44, the wall 48 will return to its initial position, and the blocking of the tilt levers 50 by each projection 48b will be released. The projection 48b of the wall 48 thus constitutes a safety element which either blocks or releases actuation of the tilt lever 50, as required, depending on its respective position.

(25) As can be seen in FIG. 3, a bent free end 49 of the bearing body 46 and a shoulder 49a associated with the free end 49 and formed in the wall 48 together form a stop, thus limiting the axial displacement of the wall 48 on the bearing body 46.

(26) In FIG. 2c, the wall 48 of the handle 44 is illustrated in its initial position again. The projection 48b is again below the tilt levers 50, which thus eliminates the blocking of the tilt levers 50 as shown in FIG. 2b. As a result of a manual force exerted on the actuating members 56, the tilt levers 50 are tilted about their tilt joints formed by a strut 54 and respective associated recess in the thickened portion 52, and the latching elements 58 are outside the groove 34b. The locking between the rotor 10 and the lid 40 has been released, and the lid 40 can be removed from the rotor 10.

(27) FIG. 3 is an exploded lateral sectional view of the rotor 10rotated by 90 relative to the views of FIG. 1 and FIGS. 2a to 2ci.e. an exploded view with the lid 40 removed, as well as of a support 106 of a centrifuge 100 which is also shown schematically in FIG. 6.

(28) When the rotor 10 is placed onto the support 106 of the centrifuge 100, the locking ball 22 will engage an aperture 110 of an abutment insert 108 which is concentrically arranged on the support 106 and screwed together with the latter. The aperture 110 is dimensioned so as to allow passage of the locking ball 22 with minimum clearance. Following after the aperture 110 is an internal contour 112 of the abutment insert 108 which widens conically in a direction opposite to the direction of removal E.

(29) Arranged in a cylindrical inner area 114 of the support 106 is a spring 24 in which a blocking unit 26 is mounted to which a spring force is applied which acts in the removal direction E, which blocking unit 26 is separately shown in FIG. 3b for reasons of clarity. The blocking unit 26 has four blocking springs 30 which are interconnected via a connecting ring 28 and each have a blocking element 30a mounted on their respective ends. The shape of the blocking elements 30a is essentially adapted to the external contour of the locking ball 22. Placing the rotor 10 onto the support 106 of the centrifuge 100 will cause the blocking elements 30a and thus the entire blocking unit 26 to be initially pressed downward, by the locking ball 22 entering the aperture 110, into the area of the internal contour 112 in the abutment insert 108 which is larger than the aperture 110 so that the blocking elements 30a can then be pressed apart. The blocking elements 30a then slide along the locking ball 22 to the point where they will ultimately surround the locking ball 22 with the rotor 10 completely in place on the support 106. The spring force will cause the blocking unit 30 to again move in the removal direction E, and the blocking elements 30a will abut on the internal contour 112 of the abutment insert 108. With the blocking elements 30a in abutment, the circumference of the locking ball 22 with the blocking elements 30a will increase to such an extent that it will no longer be able to pass through the aperture 110 of the abutment insert 108. The abutment of the blocking elements 30a on the internal contour 112 of the abutment insert 108 will thus prevent any movement of the blocking elements 30a in a radial direction. The rotor 10 is thus securely fixed in an axial direction on the support 106 of the centrifuge 100.

(30) The locking ball 22 is penetrated by a bore 32. The bore 32 extends from the locking ball 22 through the rotor head 12 and the adjacent rotor pin 34. As viewed in the removal direction E, the inner diameter of the bore 32 widens at a first shoulder 32a and again at a second shoulder 32b.

(31) Reaching through the bore 32 is an unlocking pin 36 which in turn has a first shoulder 36a which is associated with the first shoulder 32a of the bore 32, and a second shoulder 36b which is associated with the second shoulder 32b of the bore 32. For reasons of clarity, the area marked III a in FIG. 3 which shows the unlocking pin 36 inserted in the bore 32 is illustrated in enlarged detail in FIG. 3a. In the areas respectively associated with each other, the diameter of the unlocking pin 36 and the internal diameter of the bore 32 are adapted to each other so as to allow axial movement of the unlocking pin 36 within the bore 32. Axial movement of the unlocking pin 36 in the direction of the support 106 is limited and possible up to a final position in which the respective corresponding shoulders 32a and 36a as well as the shoulders 32b and 36b will then abut on each other.

(32) The longitudinal extension of the unlocking pin 36 is dimensioned such that a free end 38 thereof will be made to protrude from the locking ball 22 as the unlocking pin 36 is moved against the removal direction E, will engage the blocking unit 26 and increasingly displace the blocking unit 26 against the force of the spring 24, with the blocking elements 30a also moving along the locking ball 22 into the area of the internal contour 112 which is wider than the aperture 110 of the abutment insert 108, thus allowing the blocking elements 30a to bend outwardly. Once unlocking pin 36 reaches the above described final position, the blocking unit 26 has been moved by a distance s.sub.S to such an extent that the blocking elements 30a will completely release the locking ball 22, i.e. as the locking ball 22 passes the blocking elements 30a, the latter will be bent radially outwardly. The locking ball 22 will then be able to pass through the aperture 110 of the abutment insert 108 again, and the rotor 10 can be taken off the support 106 of the centrifuge 100.

(33) It is also conceivable to interchange the positions of the locking ball 22 and of the blocking unit 30, i.e. to have the locking ball 22 arranged on the side of the shaft, to mount the blocking unit 30 for axial movement in the rotor 10, with the internal contour 112 of the abutment insert 110 consequently tapering in the removal direction E.

(34) For activating the unlocking pin 36, an actuating pin 74 is provided in the handle 44, whichtogether with the unlocking pin 36forms an activating element 36, 74.

(35) For this purpose, a support insert 70 is incorporated in the bearing body 46 of the handle 44, concentrically to the rotor axis R, which is flush with the handle pieces 45 on the side facing away from the rotor 10. An axial bore 72 runs through the support insert 70 and tapers in steps at the end facing the rotor 10 so as to form an aperture 72a there which is smaller in diameter than the diameter of the bore 72.

(36) The actuating pin 74 is movably mounted within the bore 72 and comprises a cylindrical first portion 76 which is adapted in diameter to the internal diameter of the bore 72, as well as a cylindrical second portion 78 which is adapted in diameter to the internal diameter of the aperture 72a. The second portion 78 runs through the aperture 72a and engages an inner space 47 of the handle 44 which is delimited laterally by the bearing body 46. A shoulder 80 formed between the first portion 76 and the second portion 78 thus serves as a boundary for axially moving the actuating pin 74 into a final position, against the removal direction E.

(37) The free end of the first portion 76 is designed as a pushbutton 82 which, in its non-depressed state, will project completely from the support insert 70 and is of a height h.sub.D. When the pushbutton 82 is completely depressed, it will be flush with the free side of the support insert 70, and the actuating pin 74 will be moved against the removal direction E by a distance s.sub.B which corresponds to the height h.sub.D. The actuating pin 74 is thus moved into its above described final position.

(38) As the lid 40 is placed onto the rotor 10, the rotor pin 34 housing the unlocking pin 36 will enter the inner space 47 of the bearing body 47 of the handle 44 through the aperture 42a. Centering the lid 40 will be facilitated by the conically tapering external contour 34a on the free end of the rotor pin 34.

(39) The lengths of the unlocking pin 36 and the actuating pin 74 have been chosen such that their ends which face each other will abut on each other once the lid 40 is completely in place on the rotor 10. Thus the unlocking pin 36 and the actuating pin 74 together form an activating element 36, 74 which can be used to move the blocking unit 26 axially by the distance s.sub.S into a release position even with the lid 40 in place, and the lock between the rotor 10 and the shaft 104 can be deactivated in the manner described above, thus allowing the rotor 10 to be taken off the support 106.

(40) In the present embodiment, the height h.sub.D of the pushbutton 82 is of the same length as the distance s.sub.B and the distance s.sub.S. The pushbutton 82 may also be designed to be higher, in which case it will also protrude from the support insert 70 in its activated state. However, the height h.sub.D must not be smaller or not much smaller than the length of the distances s.sub.B and s.sub.S, else the required lifting height of the blocking unit 26 for unlocking will not be obtained and unlocking cannot be reliably ensured anymore.

(41) Similarly, it is possible to form the activating element 36, 74 as one piece and optionally either mount it in the handle 44 of the lid 40 or in the receiving chamber 18 of the rotor 10, in the rotor pin 34. When the activating element 36, 74 is mounted in the handle 44, the rotor pin 34 can be of a more space-saving design, or the rotor pin 34 can almost completely be omitted.

(42) The perspective view of FIG. 4 illustrates how the locking mechanism 50, 34b for interlocking the lid 40 and the rotor, and the blocking device 22, 24, 26 for securing the rotor 10 to the drive shaft 104 are embedded in the handle 44. The operator will thus only need one hand to operate the two unlocking means, and will not have to change the position of his hand much, either. Since the pushbutton 82 will have to be pressed down vertically to unlock the blocking device 22, 24, 26 which secures the rotor 10 to the shaft 104, whereas unlocking the device which secures the lid 40 to the rotor 10 is accomplished by exerting horizontal pressure on both sides of the two actuating members 56, the risk of incorrect use is low.

(43) Similarly to FIGS. 2a, 2b and 2c, FIGS. 5a, 5b and 5c are detailed views of the handle 44 incorporated in the lid 40 with a retaining device which, in its activated state, will prevent access to the locking element 50.

(44) As already described, the lid 40 is locked by means of the tilt levers 50. On the lower end of each tilt lever 50, a latching element 58 is provided which, in a locked state of the lid 40, will engage the groove 34a made in the rotor pin 34. This will secure the lid 40 axially to the rotor pin 34 and thus lock it together with the rotor 10.

(45) The tilt levers 50 are pivotably supported on the struts 54. Exerting a force on the actuating members 56 arranged on the upper ends of the tilt levers 50 in the direction of the rotor axis R will cause the tilt levers 50 to be tilted for unlocking in such a way that the latching elements 58 will slide out of the groove 34a, thus releasing the secure connection of the lid 40 to the rotor pin 34.

(46) As also already described with reference to FIGS. 2a, 2b and 2c, lifting the handle 44 will activate the retention of the locking. This will cause the wall 48 and the projections 48b mounted on the wall 48 to be moved axially in the removal direction E. As a result, a projection 48b each will be made to abut on its associated tilt lever 50, thus blocking any movement of the tilt levers 50. The latching element 58 will be locked in the groove 34b, and the locked connection of the lid 40 to the rotor 10 will be secured.

(47) The difference to the embodiment shown in FIGS. 2a, 2b and 2c is that cover elements 48c are additionally provided as a precaution against unintentional releasing of the locked connection.

(48) The cover elements 48c mounted on the free end of the wall 48 and facing away from the rotor axis R, together with the wall 48 of the handle 44, feature a U-shaped cross-section which is open toward the top. The cover elements 48c are dimensioned such that their free ends which point upwards will reach up to below the actuating members 56 when the handle 44 is in its non-actuated initial position, as shown in FIG. 5a. The actuating elements 56 are freely accessible in this state.

(49) The view of FIG. 5b shows the tilt levers 50 in an identical position as the one of FIG. 5a, the locking position. Here the wall 48 of the handle 44, together with projections 48b and cover elements 48c, have been axially displaced relative to the bearing body 46 in the removal direction E. The actuating elements 56 each engage the area between the cover element 48c and the wall 48 such that their free ends will no longer be freely accessible, thus preventing any exertion of a manual force by an operator and consequent release of the locked connection of the lid 40 to the rotor 10. The locked connection will thus be secured against faulty operation both by the blocking of the movement of the tilt levers 50 and by a cover of the actuating members 56.

(50) Finally, FIG. 5c is a view of the wall 48 of the handle in its initial position again in which the cover elements 48c are again located below their associated actuating elements 56. Owing to a manual force exerted on the actuating members 56, the tilt levers 50 are now tilted in such a way that the latching elements 58 are outside the groove 34a, in the unlocking position.

(51) FIG. 6 is a lateral sectional view of a centrifuge 100 according to the invention, from which a housing and a bottom have been omitted for reasons of clarity.

(52) As already described with reference to FIG. 3, the rotor 10 illustrated in FIGS. 1 to 4 is connected to the drive shaft 104 via the support 106 and rotates about rotor axis R. The drive shaft 104 is driven by the motor 102 underneath it.

(53) For safety and soundproofing reasons, the rotor 10 is surrounded by a safety vessel 116. The motor 102 engages the safety vessel 116 via an aperture 116a.

(54) Provided above the safety vessel 116 is a centrifuge lid 118 which is connected to the housing (not shown) in a conventional manner and seals the centrifuge 100 at its top.

LIST OF REFERENCE SIGNS

(55) 10 rotor 12 rotor head 12a lateral surface 12b bottom 14 receiving units 16 sample containers 16a sealing caps 18 receiving chamber 20 rotor seat 20a first portion 20b second portion 20c boundary surface 22 locking ball 24 spring 26 blocking unit 28 connecting ring 30 blocking springs 30a blocking elements 32 bore 32a first shoulder 32b second shoulder 34 rotor pin 34a external contour 34b groove 36 unlocking pin 36a first shoulder 36b second shoulder 38 free end 40 lid 42 recess 42a aperture 44 handle 45 handle pieces 46 bearing body 46a recess 47 inner space 48 wall 48a recess 48b projection 48c cover element 49 free end 49a shoulder 50 tilt lever 52 thickened portion 54 strut 56 actuating member 58 latching element 60 recess 62 springs 70 support insert 72 bore 72a aperture 74 actuating pin 76 first portion 78 second portion 80 shoulder 82 pushbutton 100 centrifuge 102 motor 104 shaft 106 support 108 abutment insert 110 aperture 112 internal contour 114 inner area E removal direction R rotor axis h.sub.D pushbutton height s.sub.B activation distance of actuating pin s.sub.S activation distance of blocking unit