Locking bolt with protected locking mechanism

Description

[0001] The invention relates to a locking bolt with a protected locking mechanism according to the preamble of claim 1.

[0002] In coordination with all relevant industries, such as the food, pharmaceutical, and cosmetics industries, as well as biotechnology, state health authorities see their primary task and objective as ensuring that products used for human nutrition or treatment, and by extension animals, are as free as possible from harmful influences. Within this policy framework, the safety, quality, and shelf life of products sold to consumers are crucial. Therefore, all consumer protection efforts aim at product safety, both preventively and sustainably, to protect against toxic substances and relevant microorganisms and to eliminate health risks.

[0003] For the aforementioned industrial sectors, some of which manufacture highly hygienic products, it is characteristic that the original focus of legislation was solely on hygiene and quality measures for the manufactured products, while for the process equipment, only the cleanliness before the start of the process was a key requirement. In recent years, legal requirements have been added to these specifications: "Hygienic Design," meaning the easily cleanable and hygienic design of the process equipment, as an important prerequisite for safe production in the interest of consumer protection.

[0004] Recent findings and economic analyses show that the desired high quality of products with a long service life can only be achieved by combining the two target variables "product" and "production facility".

[0005] The textbook "Gerhard Hauser: Hygienic Production Technology, 2008, pp. 1-7, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, ISBN: 978-3-527-30307-3" conveys the idea of ​​hygienic design or "hygiene-friendly design" using basic examples.

[0006] Today, in addition to the fundamental meaning of "health" or "promoting health," hygiene is also understood to encompass all areas that aim to avoid risks and dangers to human health through contamination by relevant microorganisms and other substances during the consumption of products.

[0007] For this reason, the manufacturing process must be optimized from a process engineering perspective (e.g., coordination of mass flows, residence times, temperatures) and monitored with regard to potential product impacts. To prevent additional contamination by microorganisms and substances that impair quality, the cleaning of equipment, apparatus, and components, as well as—especially in processes that are open to the environment during production or require inspection—the surrounding area, is carried out at the end of each production cycle. As a result of comprehensive quality assurance, all negative influences on the product must be eliminated at their source.

[0008] While product processing and cleaning have always been considered equally important in many areas of the industries mentioned, the strong influence of hygienic plant and component design was long considered irrelevant or simply neglected.

[0009] In some sectors, the prevailing opinion was that sufficiently high concentrations of suitable, often aggressive, cleaning and disinfecting agents, along with adequately long cleaning times and high temperatures, would ensure successful cleaning for virtually any system. Furthermore, it was frequently argued that for products pasteurized or sterilized immediately before filling or packaging, hygiene during production was not necessarily the decisive factor, as the elimination of relevant microorganisms in the final step was ultimately crucial.

[0010] What is often overlooked is that an increased contamination of the product with microorganisms during production can significantly impact its quality and make decontamination measures more difficult and expensive. Furthermore, the increased risk of toxic metabolic byproducts forming when the number of microorganisms is elevated and uncontrolled must be taken into account.

[0011] Due to learning processes in this area, the perspective has changed significantly in recent years, with the demand for hygienic plant design taking center stage. Technical terms such as hygienic design or cleanability are now commonplace among experts dealing with hygiene issues related to production and production facilities. Through appropriate design measures, which are now also legally required in various sectors, hygienic design aims to improve cleanability and thus cleaning effectiveness, as well as making cleaning safer.

[0012] With the patents DE202015003789U1, DE10338621B4, DE102008047041B4, DE202008013348U1 and EP2163772B1, which are attributed to the same applicant, it is known to arrange the locking mechanism of a locking bolt externally, i.e. on the radial, lower circumference of a guide sleeve.

[0013] The function of a locking bolt described therein is intended to be fully encompassed by the disclosure of the present invention.

[0014] The subject matter of EP 2 163 772 B2 discloses a detent mechanism arranged in the actuating button, which is unprotected at the lower free end of the actuating button, opposite a guide sleeve. The actuating button is guided axially displaceably on the guide sleeve by spring action. A screw thread is provided on the guide sleeve, allowing the guide sleeve to be screwed into any machine surface.

[0015] In the top area of ​​the actuating button, there is an unsealed recess to accommodate a spring-loaded, sliding release button. The locking mechanism for the locking bolt consists of radially outward-facing guide lugs on the inner circumference of the sleeve-like extension of the actuating button, which interact with opposing radial ring projections in the area of ​​the guide sleeve. Dirt particles and other contaminants can thus enter the space between the guide sleeve and the downward-facing actuating button and impair the function of the locking mechanism.

[0016] Furthermore, such an arrangement has the disadvantage of not meeting increased hygiene requirements because the radially outward-protruding parts of the locking mechanism from the guide sleeve are susceptible to contamination, prone to breakage, and otherwise do not comply with the requirements of a hygienic design. Dirt pockets can form there, preventing the use of conventional locking bolts in hygiene-sensitive environments.

[0017] The invention is therefore based on the objective of further developing a locking bolt with a known locking mechanism in such a way that it meets the increased hygiene requirements in accordance with a hygiene design.

[0018] To solve the stated problem, the invention is characterized by the technical teaching of the claim.

[0019] In a preferred embodiment of the invention, the locking mechanism is located in the sealed interior of the actuating button, which means that the (first) guide sleeve with axial sleeve-like projections extends into a central bore of the actuating button and that the locking mechanism is arranged in a sealed manner in the area between the axial projections of the guide sleeve - which thereby form a second guide sleeve - and the central bore of the actuating button.

[0020] In a preferred embodiment, the locking mechanism is arranged in a sealed manner in the central bore of the actuating button, and the second guide sleeve with its coaxial, second projections extends in a sealed manner into the central bore of the actuating button.

[0021] This achieves for the first time that no parts of the locking mechanism protrude unprotected in or on the outer first guide sleeve, which receives the movable locking pin or bolt; rather, these parts are sealed and received into the interior of the actuating button on the one hand and into the second guide sleeve with axial projections on the other, with the second guide sleeve forming a single-piece part with the first guide sleeve.

[0022] The first guide sleeve is therefore completely smooth and flat and sealed against the actuating button, and the entire locking mechanism is protected and sealed within the actuating button itself.

[0023] To meet special hygiene requirements, the guide sleeve and / or the actuating button can be made of a polished stainless steel material with a surface roughness of less than 0.04 micrometers.

[0024] According to a preferred embodiment of the invention, the locking mechanism consists of a locking sleeve arranged in the central bore of the actuating button, which is designed as a sleeve open on one side and is fixedly and immovably coaxially connected to the actuating button in the central bore of the actuating button.

[0025] The rotationally fixed connection between the locking sleeve and the inner side of the actuating button is achieved by an axially raised locking pin, which engages in a corresponding blind bore on the inside of the actuating button and thus connects the locking sleeve firmly and immovably to the actuating button.

[0026] Instead of a rotationally fixed fastening with a locking pin between the locking sleeve and the inside of the actuating button, of course all other fastening means can be used, such as an adhesive connection, a clamp connection or other types of connection that ensure that the locking sleeve is rotationally fixed and cannot be moved inside the actuating button.

[0027] In a further development of the invention, it can also be provided that the locking sleeve and the actuating button form a single, one-piece part, which means that, for example, if the actuating button is made of plastic, the locking sleeve is also connected to the actuating button as a one-piece plastic part inside the button.

[0028] In this case, it is a homogeneous injection-molded part that connects the actuating button to the locking sleeve in a material-bonded manner.

[0029] The guide sleeve can be fixed to a mounting surface in any type of fastening, e.g., in the form of a clamp fastening, a screw fastening, or a fastening in conjunction with a screw nut, wedge and other fasteners.

[0030] It is important that parts of the locking mechanism extending radially beyond the guide sleeve are no longer present, but rather that the entire locking mechanism, consisting of the locking sleeve and the associated opposing and housing-like locking contours, is sealed inside the locking bolt, specifically inside the actuating button.

[0031] This means that the locking mechanism inside the actuating button is completely sealed from the environment, because the rod seal arranged on the inside of the actuating button ensures a secure seal against the outer circumference of the cylindrical guide sleeve.

[0032] However, instead of such a rod seal, other sealing arrangements can also be used, such as an O-ring seal, a cord ring or stuffing box seal, or other sealing measures.

[0033] If stricter hygiene requirements are not a concern, the previously described rod seal can be omitted entirely.

[0034] The locking mechanism of the locking bolt with the internally integrated locking mechanism is such that the actuating button, in the locked state, is spring-loaded downwards onto the cylindrical guide sleeve, against the force of an associated compression spring.

[0035] To release the locking mechanism, the operating knob is turned approximately 90° until the detent contour of the locking sleeve disengages from the opposite, housing-mounted detent recess on the guide sleeve. Due to the spring force of the compression spring, the operating knob is then automatically moved into the raised position. It thus enters a locked rotational position, meaning it can no longer rotate independently when released.

[0036] This has the advantage that you don't have to lift the operating button against the force of the pressure spring, but you can turn it immediately to move it from one detent position to the other without having to lift it.

[0037] In a preferred embodiment of the invention, the locking contour is designed as a chamfer inclined to the longitudinal axis, consisting of two separate circular segments with different radii. One circular segment is designed as the locking contour, while the subsequent circular segments are designed as non-locking arc segments.

[0038] Instead of forming two diametrically opposed detent contours that are fixed to the housing and arranged in the detent sleeve, it is also possible to provide, for example, four such detent contours arranged in a star shape relative to each other. Other geometries are also possible.

[0039] The subject matter of the present invention is not only defined by the subject matter of the individual patent claims, but also by any combination of the individual patent claims with each other.

[0040] All information and features disclosed in the documents, including the abstract, and in particular the spatial configuration shown in the drawings, could be claimed as essential to the invention, insofar as they are novel individually or in combination compared to the prior art. The use of the terms "essential," "according to the invention," or "essential to the invention" is subjective and does not imply that the features so designated must necessarily be part of one or more patent claims.

[0041] The invention is explained in more detail below with reference to drawings illustrating only one embodiment. Further essential features and advantages of the invention will become apparent from the drawings and their description.

[0042] They show: Figure 1: Section through a latching button according to the invention in the disengaged state. Figure 2: Section through the latching button in the engaged state. Figure 3: A perspective view of the actuating button showing the latching mechanism in the engaged state. Figure 4: The same representation as Figure 3 in a frenzied state, Figure 5: one opposite Figure 4 Same representation of the actuating button in the locked state. Figure 6: a perspective view of the locking sleeve. Figure 7: a front view of the locking sleeve in the direction of arrow VII. Figure 6 Figure 8: a section through the locking sleeve after Figures 6 and 7 Figure 9: a longitudinal section through the guide sleeve. Figure 10: a front view of the guide sleeve in the direction of arrow X. Figure 9

[0043] In the Figures 1 and 2In general, a latching button is shown, which in the illustrated embodiment essentially consists of an upper actuating button 6, which can be made of any material, preferably a metal or plastic material.

[0044] The locking mechanism is arranged in the central bore 14 of the actuating button 6, which in the illustrated embodiment essentially consists of a locking sleeve 8 that is fixedly and immovably received in the interior of the actuating button 6 and which interacts with an associated guide sleeve 3 of approximately cylindrical shape, wherein the guide sleeve 3 can also be made of any material, such as a metal or a plastic material.

[0045] To meet the required hygiene standards, it is provided that the locking mechanism, consisting of the locking sleeve 8, is arranged in the central bore 14 and that, moreover, there are no radially protruding parts of the guide sleeve 3 that belong to the locking mechanism and that might be susceptible to contamination.

[0046] The guide sleeve 3 can therefore be attached to any mounting surface with any screw connection or fixing. In the illustrated embodiment – ​​which is not limiting to the invention – the guide sleeve 3 is provided with a first circumferential sealing ring 5 at its lower end, which is embedded in a radial projection of the guide sleeve 3.

[0047] Opposite this radially enlarged diameter projection with the sealing ring 5, a sealing nut 1 is provided, which is also provided with a sealing ring 5 on its radial outer circumference, which is also embedded there.

[0048] The sealing nut 1 is, incidentally, screwed onto a further sealing ring 4 on an associated external thread on the guide sleeve 3.

[0049] In the space between the two opposing sealing rings of guide sleeve 3 and sealing nut 1, a (thereby sealed) clamping receptacle 10 is formed, into which, for example, a mounting plate 11 can engage, whereby the entire locking bolt can be fixed on a mounting plate - only partially shown - and in a bore arranged there.

[0050] Instead of the sealed screw fastening of the locking button with the sealing nut 1 shown, all other sealed fastening methods are of course possible, such as a sealed screw connection in an associated cylindrical bore of a mounting plate or wedge, clamp or adhesive connections.

[0051] In the illustrated embodiment, the guide sleeve 3 has a central bore 17 in which a bolt 2 is designed to be displaceable in the axial direction by spring loading due to the force of a compression spring 7.

[0052] In the illustrated embodiment, the bolt 2 extends through the bore of the sealing nut 1 in a sealed manner and thus forms an actuating end, whereby the bolt 2 can engage in a machine-fixed bore of a machine housing (not shown) or be disengaged from this machine-fixed bore.

[0053] To meet the increased hygiene requirements according to the general description section, it is further provided that a radially inwardly directed rod seal 9 is integrated on the lower foot side of the actuating button 6, which seals against the outer circumference of the guide sleeve 3 with its inner circumference, so that the entire actuating button 6 is slidably and spring-loaded in the axial direction (in the direction of arrow 23 and in the opposite direction) sealed on the cylindrical guide sleeve 3.

[0054] Instead of an integrated rod seal 9, other sealing measures can also be used, such as an O-ring seal, a cord ring seal, or the rod seal 9 can be omitted completely if hygiene requirements are reduced.

[0055] In any case, it is important that no parts of the locking mechanism are present on the outer circumference of the guide sleeve 3, because this is completely integrated into the central bore 14 of the actuating button 6.

[0056] For this purpose, the guide sleeve 3 engages with an upwardly open second guide sleeve 12, which is an integral part of the first guide sleeve 3, in the central bore of the actuating button and the outer circumference of the second guide sleeve 12 forms a sliding surface 13 to the inner circumference of the actuating button in the area of ​​the central bore 14.

[0057] The hygienic design is achieved by the fact that the locking mechanism 27, 28 is arranged in the central bore of the actuating button 6 on the inner end face 35 of the central bore 17 and is sealed by the rod seal 9 arranged at an axial distance, and the guide sleeve 3 extends into the central bore 14 of the actuating button 6 with the coaxial, second axial guide sleeve 12, sealed by the rod seal 9.

[0058] The bolt 2 is connected, either integrally or separately, to an upper threaded bolt 19, which is screwed into an associated bore 18 on the inside of the actuating button 6.

[0059] Instead of such a screw connection, other connections, such as an adhesive bond or a weld, can also be used. It is also possible that the threaded bolt 19 is designed as a rivet bolt and riveted to the actuating button 6.

[0060] The locking mechanism essentially consists of a sleeve-shaped locking sleeve 8, which is fixed in a blind bore 21 of the actuating button 6 in the area of ​​the inner end face 35 by means of its single, acentrically and axially directed locking pin 22, and is held there immovably. It is therefore rotationally and immovably connected to the actuating button 6.

[0061] The sleeve-shaped locking sleeve 8 forms an axially downward extending sleeve extension 15, which also defines a central center bore 17, (see Figure 8 ).

[0062] The central bore 17 with the indicated, central radial play can also be completely omitted, because the sleeve extension 15 of the locking sleeve 8 can also be positively engaged with the outer circumference of the bolt 2.

[0063] The locking mechanism itself is formed by an end-face stop surface 16 in the guide sleeve 3, which interacts with an associated locking contour 28 of the locking sleeve 8, as will be shown later with reference to the further drawings according to Figures 6 to 8 will be described.

[0064] While the Figure 1 The disengaged position of the locking bolt shows the Figure 2 the locked position. This differs from the Figure 1 by moving the actuating button 6 upwards in the direction of arrow 23 and by pulling it up, thereby compressing the compression spring 7.

[0065] It is therefore pulled upwards against the force of the compression spring 7 into its locked position in the direction of arrow 23 and rotated by 90°, for example in the direction of arrow 24 around its longitudinal axis 25.

[0066] The Figure 2 shows in comparison to Figure 1 , that the operating button 6 has now been rotated by 90°.

[0067] Instead of a 90° rotation to achieve the two detent positions, other rotation angles can also be provided, such as 30°, 60°, 120°, or similar. This depends on the type of detent contour 28, 34, which can be seen in the drawings. Figures 6 to 8 will be described. More than two rest positions may also be provided.

[0068] It is further added that a central threaded bore 20 is incorporated on the inside of the actuating button 6, into which the threaded bolt 19 of the bolt 2 is screwed.

[0069] The Figures 3 , 4 and 5show the same parts with the same reference symbols, where the Figure 3 the locked state according to Figure 2 represents the Figure 4 the state of being out of control according to Figure 1 and the Figure 5 again the locked state according to Figure 2 .

[0070] The same parts are marked with the same reference symbols, so the explanation according to the Figures 1 and 2 also for the names and parts of the Figures 3 to 5 apply.

[0071] The Figure 6 Figure 1 shows a perspective view of a locking sleeve 8, which essentially consists of a cylindrical ring extension 29 having a central bore through which the bolt 2 passes.

[0072] A locking pin 22 is formed acentrically to the central bore 18, which, according to the preceding embodiments, engages in an associated blind bore 21 in the interior of the actuating button 6 and is anchored there.

[0073] Such a fastening has the advantage that a particularly reliable and simple fastening of the locking sleeve 8 inside the actuating button 6 is ensured.

[0074] A locking contour 28 is formed on the lower end face of the sleeve attachment 15, wherein the locking lug 31 belonging to the locking contour 28 extends into the sleeve attachment 15.

[0075] In another embodiment, it can also be provided that the sleeve extension 15 is cylindrical and the radially projecting, opposing locking lugs 31 are only formed at the bottom in the area of ​​the locking contour 28.

[0076] The Figure 7The special design of the locking contour 28 of the locking sleeve 8 on the lower end face shows that the two diametrically opposed locking lugs 31 form a locking area 33 and that there are intervening arc sections 30 which are not designed to lock.

[0077] It is preferred if the locking lugs 31 are formed in the area of ​​an obliquely running chamfer 32, as shown by the Figure 8 is recognizable.

[0078] The Figure 8 shows that the locking contour is formed in the area of ​​the chamfer 32 which runs obliquely at an angle to the longitudinal axis.

[0079] The formation of the raster contour 28 in an obliquely running chamfer 32 according to Figure 8 This has the advantage that you do not have to lift the actuating button 6 against the force of the compression spring 7, but you can turn it immediately to move it from one detent position to the other without having to lift it.

[0080] The chamfer 32 thus forms, so to speak, a ramp on the housing-side detent contour 34, so that lifting the actuating button is not necessary.

[0081] Instead of a sloping chamfer 32, as in Figure 8 As depicted, it can of course be provided in one embodiment that this preferred comfortable rotary movement, which does not require pulling movement, is replaced by a combined pulling-rotating movement.

[0082] In the latter case, chamfer 32 would then be omitted, and there would be a smooth end face that is not inclined at an angle to the vertical.

[0083] In this case, however, the actuating button 6 with the bolt 2 firmly connected to it would have to be lifted against the force of the compression spring 7.

[0084] Instead of the straight chamfer 32 shown here, which runs diagonally, arc-shaped chamfers can also be used, i.e., the diagonal straight chamfer according to Figure 8 , which forms the chamfer 32, can also be profiled in an arc shape.

[0085] The Figure 9 and 10 The opposite detent contour 34 of the guide sleeve 3 is shown, with the same reference numerals applying to the same parts.

[0086] The Figure 10 The front view of the guide sleeve 3 in the direction of arrow X is shown. Figure 9 .

[0087] It can be seen that there are two axially spaced guide contours, i.e. these two axially spaced surfaces 26 and 16 form the engaged and disengaged states of the actuating button 6.

[0088] The locking element 26 forms the locking contour 34, which is in Figure 10The detent contour essentially consists of two diametrically opposed detent lugs, which are also referred to as locking projections 26, while in the space between them there are two opposing stop surfaces 26, which are arc-shaped and do not serve for detenting.

[0089] The two spaced-apart guide surfaces of the locking mechanism are therefore arranged in the area of ​​the locking recess 27.

[0090] In the locked state, the locking lug 31 of the locking sleeve 8 rests on the locking projection 26 with the locking contour 34 according to Figure 10 the guide sleeve 3.

[0091] If, however, the locking lugs 31 are rotated by, for example, 90° by rotating the locking sleeve 8, then these locking lugs 31 move downwards in an axial direction through the locking recess 27 and strike the lower, bottom-side stop surfaces of the guide sleeve 3. This results in the disengaged state according to Figure 1 reached.

[0092] It can thus be seen that the locking mechanism with the spaced-apart guide surfaces 16, 26, 34, which are formed in the area of ​​a central locking recess 27 in the interior of the guide sleeve 3, is completely sealed and integrated in the interior of the actuating button 6, so that there are no radially protruding parts from the guide sleeve 3. Drawing legend

[0093] 1. Sealing nut 2. Bolt 3. Guide sleeve (first) 4. Sealing ring 5. Sealing ring 6. Actuating button 7. Compression spring 8. Detent sleeve 9. Rod seal 10. Clamping receptacle 11. Mounting plate 12. Guide sleeve (second of 3) 13. Sliding surface 14. Central bore (of 6) 15. Sleeve shoulder (of 8) 16. Stop surface (of 3) 17. Center bore (of 8) 18. Bore (of 8) 19. Threaded bolt (of 2) 20. Threaded bore (of 6) 21. Blind bore 22. Locking pin 23. Arrow direction 24. Arrow direction 25. Longitudinal axis 26. Locking shoulder (of 3) 27. Detent recess (of 3) 28. Detent contour (of 8) 29. Ring attachment 30. Arc section 31. Locking lug 32. Chamfer 33. Locking area 34. Locking contour (of 3) 35. End face area

Claims

1. A latch pin with a latching mechanism (8, 16, 27, 28), comprising a guide sleeve (3) that can be fixed to a machine part and a pin (2) connected to an actuating knob (6), which passes through a central bore (14) in the actuating knob (6) and which can be axially moved in a through-bore of the guide sleeve (3) and locked in place against and by means of the force of a compression spring (7) by actuating the actuating knob (6), wherein the pin (2) can be brought into at least two latching positions by means of the latching mechanism (8, 27, 28) disposed in the central bore (14), wherein the latching mechanism (8, 16, 27, 28) is disposed in the area of the guide sleeve (3), which extends into the central bore (14) of the actuating button (6) with axial sleeve-like projections made from a single piece of material, and consists of a latching sleeve (8) connected firmly to the actuating knob (6), which rests with latching contours (28) on the latching sleeve side on latching contours (34) of the guide sleeve (3) in the latched position and on stop surfaces (16) on the bottom side of the guide sleeve (3) in the unlatched position, characterised in that the latching mechanism is disposed in a sealed manner in the area between the axial projections of the guide sleeve (3) and the central bore (14) of the actuating knob (6), and in that the latching sleeve has at least two detents (31) which, in the latched state, rest on a locking projection (26) with the latching contour (34) inside the guide sleeve (3), and in that opposite latching recesses (27) fixed to the housing are disposed in the interior of the guide sleeve (3), into which the detents (31) engage when in the unlatched state.

2. The latch pin according to claim 1, characterised in that a rod seal (9) is disposed at the foot end of the actuating knob (6), which is designed to be axially displaceable in a sealed manner on the outer circumference of the guide sleeve (3) together with the actuating knob (6).

3. The latch pin according to claim 1 or 2, characterised in that the latching sleeve (8) fixed to the inner end face area (35) of the actuating knob (6) engages with its sleeve projection into a coaxial, second axial guide sleeve (12) of the first guide sleeve (3), which is formed by the axial sleeve-like projections.

4. The latch pin according to claim 3, characterised in that the outer circumference of the second guide sleeve (12) forms a sliding surface (13) to the inner circumference of the actuating knob in the area of the central bore (14).

5. The latch pin according to any one of claims 1 to 4, characterised in that the actuating knob (6) can be rotated by approximately 90° for unlatching until the latching contour (28) of the latching sleeve (8) disengages from the opposite locking recess (27) on the guide sleeve (3), which is fixed to the housing, whereby the operating knob (6) can be automatically moved into the raised position due to the spring force of the compression spring (7).

6. The latch pin according to any one of claims 1 to 5, characterised in that there are a total of two latching positions between the latching sleeve (8) and the guide sleeve (3).

7. The latch pin according to any one of claims 1 to 6, characterised in that the latching contour (28) of the latching sleeve (8) consists of two diametrically opposite detents (31), which each form a latching area (33) between them, and in that there are curved sections (30) between them which are not designed to latch.

8. The latch pin according to any one of claims 1 to 7, characterised in that the latching contour (28) is formed in the area of a chamfer (32) running at an angle to the longitudinal axis, which forms a run-up slope on the latching contour (34) on the guide sleeve side, so that it is not necessary to lift the actuating knob (6) for the purpose of actuation.