Self-resetting safety element and coupling comprising several of these safety elements

Abstract

The invention relates to a safety element (5a) with self-resetting properties for a clutch (1) comprising two clutch elements (2, 3), wherein in an engaged state a torque can be transmitted between the two clutch elements (2, 3), and wherein, by means of the safety element, the two clutch elements (2, 3) can be switched to a disengaged state depending on the torque and can be automatically reset to the engaged state. The invention further relates to a clutch comprising at least one safety element (5a) according to the invention.

Description

The invention relates to a safety element according to claim 1, which is intended for a coupling. It has the property of decoupling as a function of torque in the event of a fault due to an overload. In addition, the safety element can then automatically return to the engaged state. The invention also relates to a clutch comprising a plurality of safety elements according to the invention, in particular a shaft clutch which can be shifted as a function of torque.The safety element is designed for a coupling which comprises two coupling elements, which can be understood as coupling halves. In the case of a shaft clutch, a torque can be transmitted between the two clutch elements in the coupled state, wherein the two clutch elements can be automatically switched into the uncoupled state by means of the safety element depending on the torque, i.e. when a defined torque is exceeded, with the proviso that the safety element comprises: a plunger, which can be displaced in its axial direction by means of a provided bearing in order to provide their coupled state or the uncoupled state in the assembled state of the clutch, a latching element, which bears against the plunger, for example a ball, wherein the latching element preferably bears against an end face of the plunger, a spring device, by means of which a spring force can be transmitted as far as into the plunger and further into the latching element, for example a disk spring pack, wherein the plunger is provided with a shoulder element, which protrudes in the radial direction on the tappet, preferably a circumferential annular shoulder element, wherein at least one transmission body is provided, which is in contact with the shoulder element on the one hand and further with at least one pressure body and interacts therewith, wherein the transmission body is, for example, a rolling body and preferably the pressure body is designed as a circumferential annular pressure body, for which purpose the pressure body has a deflection surface and the shoulder element comprises two functional surfaces, namely an inclined surface which likewise points in the axial direction and a laterally arranged resting surface, wherein the transmission body, in the coupled state of the clutch, is in contact with the inclined surface of the shoulder element in a manner transmitting the spring force, while in the uncoupled state of the clutch (neutral), it bears against the lateral resting surface of the shoulder element, and with the further proviso, in the assembled state, the plunger and the latching element are assigned to a first of the two coupling elements of the coupling, and in that the other second coupling element is assigned a latching region, for example a conical or spherical opening, which latching region is formed complementary to the latching element. The latching region expediently forms a component of the security element or is assigned to it.Safety elements of this type and couplings equipped therewith are used for heavy-duty machines, for example for machines in mining, the construction industry or in conveying installations, for example cranes, for example container cranes. In the case of a container crane of a modern port terminal, there are particular requirements, for example, due to the increasing automation.Safety elements are also known which, when they are disconnected after a malfunction and the clutch elements are disconnected, cannot automatically return to a connected state. In this type of safety element, the return must necessarily be brought about by manual actuation, which is labor-intensive and always requires an operator on site. An example of this is given in US 2010 / 0224713 A1, which proposes a safety element and a coupling provided therewith. Each safety element is arranged on one clutch half and comprises a plunger which, in the coupled state, can transmit a torque to the other clutch half by spring force in an advanced position. After a malfunction, the plungers and latching elements of all safety elements are pushed back into a position in which a spring force can no longer be transmitted into the plunger. The transmission of the force from the spring device is neutralized in an interrupted manner. In order to switch the clutch back to a torque-transmitting operation, the transmission of the spring force into the plunger must be restored and the neutralization must be canceled. In the aforementioned prior art, this switching is to be brought about only by manual intervention, which can take place, for example, by a targeted hammer strike and requires operating personnel.A generic safety element which has a self-restoring function has been proposed by the applicant in DE 10 2019 110 297 B3. With this safety element or a clutch equipped therewith, after a malfunction has taken place, when the clutch halves are separated, it is possible to engage again without having to manually actuate each safety element by an operator. In this prior art, a mechanism is provided which comprises an actuating lever arranged on the outside of the housing, which actuating lever can be pivoted against the plunger by spring force in order to achieve a return to the coupled state. The present application now seeks to provide another improved solution to this problem.The object of the invention is to provide a safety element which, installed in a clutch, allows renewed engagement after disengagement and disconnection of the torque transmission for the sake of safety, without the need for an operator who would have to effect a manual resetting of each plunger of the many safety elements on site at the operating point of the clutch.According to the invention, the object is achieved in that the resting surface of the shoulder element of the plunger is further developed with respect to an action surface which has an inclination relative to the axial direction of the plunger, namely is inclined by an angle α with respect to the axial direction of the plunger.The direction of the proposed inclination of the action surface corresponds here to the direction in which the inclined surface of the shoulder element is also inclined. The action surface deflects the spring force on the one hand and moreover brings about a transmission of the spring force. The transmission is designed such that the tappet is only acted upon with a defined low force component in the axial direction, so that the renewed coupling in this direction takes place in a material-saving manner.The appropriate measure for the inclination of the action surface can be determined empirically. The latching elements can expediently be moved back into the latching regions only if the rotational speed difference between the coupling halves is small, because in this way, renewed coupling is possible in a material-preserving manner with a low restoring force on the plunger.If the transmission body is designed as a rolling body, it does not yet have to execute a pure rolling movement; instead, sliding components with the tappet or the pressure bodies can occur. This is then a proportional rolling and a proportional sliding.According to this new concept, safety elements can be provided which are designed, for example, for different torques and / or in stages according to different sizes. Expediently, type series of security elements can be provided. Advantageously, for each safety element of a series, a suitable angle is defined for the inclination of the action surface of the shoulder element of the plunger. The angle can be determined empirically for each variable or for each desired torque of the respective safety element, for example.During operation of a clutch, both clutch elements (clutch halves) rotate and can transmit a certain maximum torque. The overall performance of the clutch depends on the properties of the safety elements used and on their number. This results in a cumulative performance corresponding to the number of safety elements of the clutch present. When the maximum torque is exceeded, the latching elements and plungers of all safety elements simultaneously move back out of the latching regions counter to the force of the spring device and prevent a further transmission of torque. The transmission body, which is preferably a ball, no longer bears completely neutrally against the action surface of the plunger. As a result, a force component can be introduced into the plunger in the axial direction, which force component advances the plunger in the direction of the latching region.In the case of the safety element of US 2010 / 0224713 A1 and DE 10 2019 110 297 B3, the resting surface is provided in each case on the shoulder element of the plunger. If, in the uncoupled state, the transmission bodies (balls) bear against the resting surface, then the movable pressure body can still press against the balls, but the balls can no longer deflect force into the tappet via the resting surface. The spring force exerted by the spring device is neutralized. The coupling halves are separated as long as the balls remain in contact with the resting surface. Both the safety element of US 2010 / 0224713 A1 and that of DE 10 2019 110 297 B3 require a high outlay, either a expenditure on personnel or a outlay on apparatus, in order to act on the plunger from the outside.In contrast, the new solution proposed here changes the function of the resting surface by having it turned into an action surface. The action surface is expediently inclined at an acute angle with respect to the axial direction of the plunger. When the movement of the transmission balls on the action surface is redirected, a defined transmission ratio in the play is due to the angle α of their inclination. By varying the angle of inclination α, the transmission ratio of the action surface can be adapted. It is desired to direct a relatively low axial force into the plunger and to have it again advance towards its engaged position. The transmission ratio is expediently such that the latching elements can only be moved back into the latching regions when the rotational speed difference between the clutch halves is small. Only with a significantly reduced restoring force on the plunger should a renewed coupling be permitted.As a result, a clutch which is equipped with safety elements according to the invention can now be automatically recoupled in the event of a malfunction which has led to a disengagement and an interruption of the torque transmission, merely by slow restarting of the driving clutch element. Before reengagement, it is always advisable to eliminate the problem which is responsible for exceeding the torque. It is only then expedient to set the clutch slowly back into operation in order to automatically re-engage it. For this purpose, the driving clutch element is set into rotation so slowly that the small restoring axial force transmitted into the plunger is sufficient to advance all the latching elements of one clutch half into the latching regions of the other clutch half and thus again to enable the transmission of torque.The transmission ratio set by means of the inclination of the action surface is selected in a targeted manner such that renewed engagement of the latching element is only possible in the case of a definedly low rotational speed difference. It is therefore material-saving. As mentioned, the clutch is expediently initially brought completely to a standstill and, before a renewed startup, the cause of the torque exceeding is sought and eliminated before starting up again and engaging.A coupling provided with the proposed safety element can thereby advantageously be put into operation again without having to manipulate each plunger manually or by means of a complex mechanism from the outside by an operator and bring it into its advanced position. It is expedient to carry out the movement so slowly that the transmission-induced low axial force component for the plunger is sufficient to move it into its advanced, engaged position. Then, the clutch can again transmit to it the torque for which it is provided.Advantageously, the angle α of the inclination of the resting surface of the shoulder element is in a range from 3° to 12°, preferably in a range from 5° to 10° and particularly preferably in a range from 7° to 8°.Advantageously, a first axially movable pressure body and a second pressure body are provided, wherein the second pressure body is arranged fixed relative to the housing.Expediently, both pressure bodies are spring-loaded directly or indirectly, wherein at least one of the two pressure bodies has an oblique deflection surface, wherein each of the deflection surfaces is in contact with the transmission body, and wherein at least the deflection surface of one of the two pressure bodies is arranged inclined at an angle, preferably an acute angle, with respect to a radial plane.The mounting of the plunger can advantageously be integrated into a housing, wherein the housing has a fastening means which is designed for the purpose of simple mounting of the safety element on a coupling element. If the housing has a cylindrical shape, then an external thread, for example, can be provided on the housing as fastening means, which external thread can be screwed into a complementary internal thread of the coupling element.The housing is expediently provided with an adjusting means by means of which, in the assembled state, its axial position relative to the supporting coupling element can be adjusted. It is considered important for the proposed safety element to enable, via this, adjustability of the axial position, a plurality of components which are arranged in a row in the assembled state. The relevant components are the plunger, the latching element and the latching region. They should be arranged as free of play as possible or with a defined small play with respect to one another. The plunger and the latching element are located in the housing which is assigned to one coupling element, while the latching region is assigned to the other coupling element. This results in certain positional tolerances between the mentioned components in their axial direction, which can be compensated for by means of the adjustability of the housing.The aforementioned measure is considered not only as a function of the solution for the underlying object indicated above, but also as an independent inventive solution for the deviating technical problem which occurs in the positional tolerances of the stated components. For this reason, starting from the preamble of claim 1, a safety element is proposed with this, which is additionally provided with the aforementioned adjustment means for the housing in order to adjust its axial position relative to the supporting coupling element and indirectly adjust the axial position of the components tappet, latching element and latching region relative to one another.The aforementioned independent solution for the adjustability of the components mentioned is supplemented in that the latching region is formed as an exchangeable latching region element which has a fixed positioning aid, wherein the positioning aid interacts with a stop means of the relevant coupling element in the assembled state.In a coupling with a plurality of safety elements, each of the latching elements (e.g. balls) can advantageously be brought into contact with each of the latching region elements without having to pay attention to an aligned position of the two coupling elements, because for example only one latching region element would be suitably set for each latching element.Advantageously, a guide bushing is assigned which, in the assembled state, serves for guiding the plunger and / or for guiding the latching element, wherein the guide bushing is likewise assigned to the first coupling element concentrically with respect to the plunger.The guide bushing can be assigned as a separate component or it is assigned as an integral component to the safety element, for example is assigned to a housing part of the safety element.The housing can have a closure element as a housing part, wherein the closure element acts as a counter bearing for the spring device and / or acts as a guide for the plunger and / or the latching element.The closure element expediently comprises a means by means of which its axial position relative to the housing can be adjusted. The closure element is simply provided with a guide bore for the plunger and has an edge with an external thread. The external thread can serve as a means for fastening. Moreover, the external thread may constitute the aforementioned means for adjusting the axial position. The external thread of the closure element expediently interacts with a matching internal thread which is provided in the housing, preferably it is a fine thread. Furthermore, an integrated securing element can be provided, for example an aluminum piece, which is embedded in a blind bore which is arranged transversely thereto in the region of the external thread. The aluminum piece reaches into the area of the external thread and is only deformed when the external thread is screwed into the internal thread of the housing and a stopping effect is achieved, similar to the inserted plastic of a self-locking hexagonal nut DIN 985, which deforms during the screwing in and acts as a screw lock.The spring device can comprise at least one disk spring; preferably, a disk spring pack consisting of a plurality of disk springs is provided.The tappet and / or at least one of the pressure bodies can be provided on its deflection surface with at least one radially extending groove which, in the assembled state, acts as a guide for the transmission body.The latching element and / or the latching region element are expediently produced from a ceramic material.The pressure body and / or the transmission body can be made of a ceramic material.The static or stationary pressure body and the movable pressure body can alternatively be made of a metal alloy. They are expediently subjected to a treatment by means of which improved wear resistance can be provided. The transfer body can also be made of a metal alloy and be subjected to a treatment for improving the wear resistance. The treatment for the mentioned components can be a heat treatment in order to cure, for example, printing bodies and / or transfer bodies made of steel, or it can be a treatment in the form of a coating which applies a material which improves the wear properties, for example a coating with chromium, in particular a hard chromium layer.It is furthermore expedient if the components within the housing are operated in the presence of a suitable lubricant.It is furthermore proposed for the plunger to be composed of several parts from at least one plunger shank and a shoulder element, in particular a shoulder ring, which can be connected thereto. The shoulder ring may have a conical action surface or the conical action surface is additionally provided with radial grooves. A suitable connection between the plunger shaft and the shoulder ring establishes a defined fixed association between the plunger shaft and the shoulder ring, in particular in the axial direction. The two-piece design has the advantage of being able to exchange the shoulder ring separately. During operation, it is subject to particular wear and may have to be replaced at a point in time when the tappet shaft can be used even further. Then the existing plunger shaft is simply provided with a new shoulder ring. In addition, it is thus possible to subject the shoulder ring to a targeted treatment which improves its wear properties and leaves the plunger shaft untreated or subjects it to another suitable treatment.Furthermore, a clutch is proposed comprising two clutch elements which can be rotated about an axis and which can be switched into an engaged state and into a disengaged state, wherein a torque can be transmitted in the engaged state, wherein at least one safety element according to one of Claims 1 to 16 is arranged on one of the clutch elements on a defined diameter and concentrically with respect to the axis of rotation of the clutch element (preferably axially or radially) and, in the case of a plurality of arranged safety elements, a defined distance of the safety elements from one another is preferably provided, and wherein a corresponding number of engagement region elements are arranged on the second clutch element on an identical diameter and concentrically with respect to the axis of rotation thereof, to be precise at congruent distances as the safety elements.Advantageously, a circumferential groove is provided on the second coupling element, which groove interacts with the latching elements of the safety elements in the uncoupled state. The cross section of the groove is expediently adapted to the cross section of the latching element, for example to the cross section of a spherical latching element.The invention is illustrated by way of example in a drawing and described in detail with reference to a plurality of figures below. The following are shown: FIG. 1 shows a coupling provided with six safety elements according to the invention, FIG. 2 shows a sectional illustration of a detail of a safety element according to the prior art mounted on a clutch and illustrated in the engaged state, FIG. 3 shows a sectional view of a portion of the known safety element of FIG. 2 in a fictitious separated state of the coupling, FIG. 4 shows a sectional illustration of a detail of a first exemplary embodiment of the security element according to the invention mounted on a coupling and illustrated in the coupled state, FIG. 5 shows a sectional illustration of a portion of the exemplary embodiment of FIG. 4 in another sectional plane in the coupled state, FIG. 6 shows a sectional illustration of a portion of the exemplary embodiment of FIGS. 4 and 5 in a separated state of the coupling, FIG. 7 shows a perspective illustration of an alternative plunger for a second embodiment of the security element according to the invention, FIG. 8 shows a perspective illustration of an alternative movable pressure body for the second embodiment of the security element according to the invention, FIG. 9 shows a perspective illustration of an alternative stationary pressure body for the second embodiment of the security element according to the invention.FIG. 1 shows a coupling 1 according to the invention, which has two coupling elements 2 and 3 (coupling halves) which are movable relative to one another and can be switched as a function of the torque. In the present example, the coupling elements 2 and 3 are rotatable about an axis of rotation 4 of the coupling 1. Therefore, the clutch 1 is a shaft clutch. It is rotationally rigid and switchable. A changeover is possible between an engaged and a disengaged state and takes place as a function of the torque.The coupling 1 is provided, for example, for drive trains of machines, such as machines in mining, the construction industry or in conveying installations, such as cranes. In particular, an application for container cranes is provided. In such machines sudden overloads may occur, which jeopardize components of the machine, such as motors, transmissions, etc. To protect them, the proposed clutch 1 disconnects the power transmission between the two clutch elements 2 and 3 so that overloading is kept away from the mentioned components of the machine and this is protected. The clutch 1 can therefore be referred to as a safety clutch or overload clutch.In order that the clutch 1 can fulfil the torque-dependent safety function, it is provided with six safety elements 5a according to the invention. Each safety element 5a has a certain capacity for transmitting a moment. In the present example, the torque that can be transmitted overall by the clutch 1 is based on six safety elements 5 a, so that the clutch 1 in principle has six times the performance of an individual safety element 5 a.The safety elements 5a are subject to wear. Certain components of the safety element 5a, which are critical for operating safety, are usually regularly inspected and optionally exchanged.In order to improve the service life of the safety element 5a according to the invention, they are provided with means for reducing wear, as follows.The coupling element 2 carries the six safety elements 5a. For this purpose, it is designed like a flange. The positions for the safety elements 5 aare distributed on the coupling element 2 on a circle (pitch circle) which is coaxial to the axis of rotation 4 of the coupling 1. Each safety element 5 ais constructed rotationally symmetrically and has a central axis 6 a. With the center axis 6 a, it is positioned on the pitch circle of the coupling element 2. In the present example, the central axes 6 aof the safety elements 5 aare arranged parallel to the rotational axis 4 of the coupling 1 or of the coupling element 2. Alternatively, safety elements 5 acan also be arranged on a coupling element in a radial orientation, for example in order to obtain a coupling acting in the axial direction.FIGS. 2 and 3 show a safety element 5 b, which is part of the prior art, which is attached to a coupling element 2 of flange-like design. The coupling element 2 has a mounting plane 7 which is perpendicular to the axis of rotation 4 and the safety element 5 bhas a defined mounting plane 8. In the assembled state shown, the assembly plane 8 of the safety element 5 bis in contact with the assembly plane 7 of the coupling element 2. the relative position of the coupling element 2 and safety element 5 bis thereby fixed in the axial direction in this prior art. The safety element 5 bincludes a plunger 9 in a housing 10, wherein a housing edge 10 adefines the mounting plane 8 of the safety element 5 b. The plunger 9 is indirectly spring-loaded and presses against a latching ball 11. According to FIG. 2, the latching ball 11 is latched in a latching region 12 which is arranged on the opposite coupling element 3 and can be axially adjusted by means of a set screw 13. The plunger 9 has a shank on which a shoulder element 14 is provided circumferentially. The shoulder member 14 is in contact with balls as transfer bodies 15. In Fig. 3 is shown the disengaged state of the safety element 5b, in which a cylindrical resting surface 16 as part of the shoulder element 14 has come into contact with the transmission bodies 15. In order to switch over from the uncoupled state back into the coupled state, the plunger 9 must be advanced, actuated from the outside, and thus the latching ball 11 must be pressed back into the latching region 12.FIG. 4 illustrates a first embodiment of the security element 5 aaccording to the invention, which has a self-restoring function. By means of this function, it can be automatically switched over from a decoupled state into a coupled state. For a clutch provided therewith, this means that it can be automatically switched from a separated state of the clutch halves to the engaged state. For comparable features, the same reference numerals are used for the sake of simplicity as previously in the description.FIG. 4 shows in particular that the safety element 5 ais mounted on a coupling element 2 in a different manner than in the prior art. The proposed safety element 5 aincludes a rotationally symmetrical plunger 9, which is modified in relation to the prior art and on which the cylindrical resting surface is replaced by a frustoconical action surface which has an inclination with respect to the axial direction of the plunger, in the present case an angle of 7.5° with respect to the central axis of the plunger 9. According to FIG. 4, a front end 17 of the plunger presses against a spherical latching element (latching ball 11), wherein the plunger 9 is arranged in a housing 10 which has a bearing for the plunger 9 and enables the latter to be displaced in its axial direction. The internal structure in the housing 10 of the safety element 5a corresponds at least largely to the structure of the known safety element according to FIGS. 2 and 3. In contrast to this prior art, however, the safety element does not need to provide a housing edge as a mounting plane for fixed positioning on the relevant coupling element 2, and otherwise the plunger 9 differs by the inclined action surface 49 mentioned above.For mounting on the coupling element 2, the housing 10 is provided with a combined fastening and adjusting means 18, by means of which its axial position relative to the supporting coupling element 2 can be adjusted. The housing 10 is arranged coaxially around the plunger 9 and has two end faces 10 band 10 c. The end faces 10 band 10 cform a bearing which has bearing openings L 1 and L 2 respectively which serve as guide bearings for the axial movability of the plunger 9. In each of the bearing openings, a seal S 1 or S 2 is arranged. Simply, the fastening and adjusting means 18 is an external thread 19 provided externally on a cylindrical side wall 20 of the housing 10. The external thread 19 is expediently designed as a fine thread. Matching this, the coupling element 2 is provided with a complementary internal thread 21, into which the external thread 19 of the housing 10 can be screwed. The screw connection consisting of the external thread 19 and the internal thread 21 has a double function. It serves on the one hand for mounting and fastening and on the other hand for the mentioned axial adjustability. The axial position of the housing 10 determines the axial position of the plunger 9, which is arranged in a row with the latching ball 11 and in series with the associated latching region 12, which is arranged on the other coupling element 3. The appropriate depth of screwing for the housing 10 is found during assembly. What is desired, moreover, is a play-free contact between the plunger 9 and the latching ball 11 and, as a result, a play-free contact between the latching ball 11 and the latching region 12.Furthermore, the plunger 9 is indirectly under a prestress which is generated by a spring device 22 arranged in the housing 10.Alternatively, the screw-in depth of the housing 10 can also be selected such that during assembly a slight clearance is provided between the plunger / latching ball / latching region, in order for example to achieve freedom from clearance only when the machine has been warmed up and has reached an intended operating state. A certain thermal expansion of the components involved can reduce or eliminate play to a defined extent. During assembly, the housing 10 can be screwed in, for example, with a defined torque, in order subsequently to rotate the housing 10 back in the opposite direction by a defined angle and thus to generate a defined clearance.The final screw-in depth of the housing 10 in the coupling element 2 is expediently secured. A suitable means 24 is provided for securing, as in the example of FIG. 4 a threaded pin 25 which is arranged in a bore 26 of the coupling element 2. The threaded pin 25 presses in the radial direction against the external thread 19 of the housing 10 in the screwed-in state, fixes its position relative to the coupling element 2; in order to conserve the external thread 19, an intermediate piece 27 made of aluminum as soft metal is provided in front of the tip of the threaded pin 25, which intermediate piece is pressed against the external thread 19 of the housing 10 without damaging it. The intermediate piece 27 is deformed and thereby achieves a stop effect, similar to the plastic of a self-locking hexagonal nut DIN 985, which is deformed during screwing in and counteracts the loosening of the screw connection.The latching regions 12 for the latching balls 11 of each safety element 5 aare arranged on the other coupling element 3. In the present example, the latching regions 12 are each formed as a replaceable latching region element 28. The engagement region element 28 has an external thread which is screwed into an internal thread of the coupling element 3. Each engagement portion element 28 has an engagement recess 29, here a recess with a conical inner surface 30. The protruding collar 31 cooperates in the assembled state with a radial surface of the coupling element 3, which serves as a stop means. The correct axial position is always defined for the engagement region element 28. As a result, it has become possible to dispense with having to bring the two coupling elements, as in the prior art, into a specific rotational position relative to one another before coupling. The proposed engagement area elements 28 are manufactured with a quality and dimensional accuracy which is so good that the engagement ball 11 of each safety element 5 aof the coupling can interact as desired with each mounted engagement area element 28. In this way, the proposed safety element 5a generally facilitates the coupling.FIGS. 5 and 6, like FIG. 4, relate to the first exemplary embodiment of the security element. It differs from the prior art by a modified tappet 9, the second functional surface of the shoulder element 14 of which forms an action surface 49 which has an inclination with respect to the axial direction of the tappet 9. In the present example, the action surface is inclined by an angle α of 7.5° with respect to the axial direction of the plunger 9. In the example, the action surface 49 is arranged circumferentially on a shoulder ring 14 a. This results in a frustoconical shape of the action surface 49.In comparison with FIG. 4, FIGS. 5 and 6 show the first exemplary embodiment in a different sectional plane, wherein FIG. 5 relates to the engaged state and FIG. 6 shows the disengaged state, in which the plunger 9 and the latching ball 11 assume a retracted position; the clutch is disconnected. The latching ball is pulled back from the latching region. In FIG. 6, the latching region element 28 is shown in simplified alignment with the plunger and the latching ball. In practice, however, the latching region element 28 has then already rotated further; during the further rotation, the latching depression 29 has pushed the latching ball 11 back into that position shown in FIG. 6. In this respect, FIG. 6 is a simplified theoretical illustration of the uncoupled state, which shows the engagement region (simplified) at a wrong rotational position.Furthermore, in the sectional plane of FIG. 5, a further threaded pin 32 can be seen in a further pin bore 33 in the coupling element 2, because the section is located in a different sectional plane than the section in FIG. 4. It serves for mounting and securing the position of a guide bush 34, which is provided on its outer surface with a V-shaped circumferential groove. The tip of the threaded pin 32 is screwed into the V-shaped groove and thus fixes the position of the guide bushing 34, which serves for guiding the latching ball 11 and also for guiding a front cylindrical end (end face 17) of the plunger 9. For this purpose, the guide bush 34 is provided with a first cylindrical inner surface 35 which forms the guide for the latching ball 11. A second cylindrical inner surface 36 forms the guide for the front end 17 of the plunger 9. The latching ball 11 in this example has a larger diameter than the front end 17 of the plunger 9. Between the cylindrical inner surfaces 35 and 36, the guide bush 34 has the conical inner surface 37, which serves as a stop in order to limit the movement of the latching ball 11.The coupling element 2 has a larger diameter than the coupling element 3 and it accommodates a shaft sealing ring 38 (sizing), which comprises a sealing lip 39 which bears against the coupling element 3. The shaft sealing ring 38 is arranged in such a way that an introduction of dirt into the guide bushing 34 and the latching region 12 is counteracted.In the sectional illustration of FIG. 5, two transfer balls 15 are illustrated, which are each in contact with a stationary pressure body, which is configured annularly as a pressure ring 40. In addition, an axially movable pressure body is provided, which is designed as a movable pressure ring 41. Finally, the plunger 9 has a shoulder element 14 which is of annular configuration as a shoulder ring. The shoulder ring comprises two functional surfaces. A first functional surface 42 is an inclined surface which is formed as a circumferential fillet 42 a. The fillet is designed such that its cross section conforms to the shape or to the radius of the transfer balls 15. a second functional surface 16 aof the shoulder element 14 is formed by a cylindrical resting surface 16, which in the present example, as in the prior art, is arranged parallel to the axial direction of the plunger 9.Furthermore, FIG. 5 shows the spring device 22, which comprises six disk springs, which are assembled to form the disk spring pack 23. In the engaged state shown, the disk spring pack 23 is in a slightly prestressed state. On the end face 10 cof the housing 10, a housing opening is provided with a closure element 43 which serves as a counter bearing for the disk spring pack 23 and comprises one of the bearing openings for the plunger which is provided with the seal S 2. The closure element 43 is designed to be able to set a prestress of the disk spring pack 23 or to remove prestress. For this purpose, a cylindrical inner wall 44 of the housing 10 is provided with an internal thread 45 and the closure element 43 has an external thread 46 cooperating therewith. Thus, the closure element 43 can be screwed into the housing 10 and can be prestressed more or less strongly against the disk spring pack 23 or can leave it relaxed. In order to ensure the desired adjustment, the cylindrical surface of the closure element 43 provided with the external thread 46 is provided with a pocket, simply a radial blind bore 47, into which a soft material, for example an intermediate piece 48 made of aluminum, is introduced. The soft material has no thread turns, but comes into contact with the internal thread 45 of the housing 10 during assembly and is thereby deformed. The deformed intermediate piece 48 serves to secure the adjusted position of the closure element 43. the deformed intermediate piece 48 achieves a stopping effect, such as the embedded plastic of a self-locking hexagonal nut DIN 985.The spring force of the disk spring assembly 23 acts on the transmission ball 15 via two deflecting components, namely the static pressure ring 40 and the movable pressure ring 41, the latter in turn diverting a component of the spring force into the annular shoulder element 14 of the plunger 9. The plunger 9 is thereby acted upon by a force component which prestresses it in the direction of the latching region 12.In FIG. 6, which shows the safety element in a separated state of the coupling, the plunger 9 has been pulled back out of the engagement region 12, whereby the transmission balls 15 have been moved radially outwards as far as beyond the first functional surface 42. The transfer balls 15a now bear against the second functional surface, i.e. against the action surface 49, which is inclined at an angle α of 7.5° with respect to the central axis of the plunger 9.The spring force emanating from the disk spring pack 23 furthermore presses against the movable pressure ring 41, which acts on the transmission balls 15 aand gives them a radially inwardly directed movement component. The transmission balls 15 ain turn redirect over the inclined action surface into the plunger and impart an axial movement component thereto in the advancing direction, whereby the plunger 9 presses the latching ball 11 in the direction of the latching region 12.In contrast to the prior art, in the uncoupled state, the inclined action surface 49 immediately deflects a force component and generates a advancing movement into the plunger 9 via the transmission balls 15 a.Due to the flat inclination of the action surface 49 (acute angle α), the spring force is translated at the action surface. The transmission ratio is selected such that a defined limitation of the force component takes place, which advances the plunger 9 in its axial direction. This is intended to allow the engagement process of the latching balls 11 into the latching regions 12 in a material-saving manner. The force component is dimensioned to be so low that it is preferably possible to engage only when there is a small rotational speed difference. With a larger rotational speed difference, a larger advancing force would be required in the tappet 9, but this would entail a higher material wear which the invention would like to prevent. The small advancing axial force on the one hand reduces the wear immediately after a malfunction if the clutch elements 2 and 3 are still in a decaying rotation and are subject to a material-wearing frictional contact on account of a rotational speed difference which is still present. On the other hand, a later startup can also take place in a material-saving manner.In the first case, when the clutch 1 has disengaged as a function of torque in full operation, the clutch elements 2 and 3 are initially still in a rotational movement, wherein a certain rotational speed difference can quickly be set. Then, detent balls 11 and detent portions 12 overrun while moving at different speeds, and this certain frictional contact causes material wear. However, since the plungers 9 and the detent balls 11 are acted upon according to the invention by a definedly small advancing axial force component, the wear in this operating phase can be kept low.During a new start-up, it is recommended that, starting from the standstill of both coupling elements 2 and 3, the driving coupling element 2 or 3 be allowed to restart only slowly in order to press the latching balls 11 gently into engagement with the latching regions 12 of the coupling element 3 with the defined low advancing force arriving in the plunger 9. The only way of coupling that works is necessarily material-saving with the proposed safety element.Fig. 7 shows a design of an alternative grooved plunger 9b which can replace that plunger 9 of the first embodiment shown and then gives a further embodiment of the security element 5a according to the invention. The grooved plunger 9 bhas a cylindrical shaft and an annular shoulder member (shoulder ring 14 b) having two functional surfaces based on those functional surfaces of the first embodiment according to FIGS. 5 and 6, the plunger 9 of which has a shoulder member 14 having two functional surfaces. The first functional surface is an inclined surface which is formed as a circumferential fillet 42 a. The second function surface is the action surface 49 that has an inclination with respect to the axial direction (center axis) of the plunger 9. As in the first embodiment, a safety member 5a provided with the grooved plunger 9b has a self-restoring function. Due to the self-restoration, when the grooved plunger 9b has come to the disengaged state, it is applied with an axial force which advances it toward its engaged state position as in Fig. 5.According to FIG. 7, additional radial grooves 53 are provided, which extend over both functional surfaces, wherein the second functional surface is arranged in the region of the action surface 49 (conical outer surface). Because only the grooves 53 interact with the transmission bodies, in the present example the groove surface of each groove 53 serves as a substitute for the frustoconical action surface 49. advantageously the grooves 53 have the same inclination as the conical outer surface which forms the action surface 49 in FIG. 5. In the assembled state, the radial grooves 53 in FIG. 7 act as a guide for the respective transmission body 15, preferably rolling bodies. In the present example, the proposed transfer balls 15 aare provided as the transfer body. The cross sections of the radial grooves 53 are, like running grooves of a rolling bearing, adapted to the shape of the transfer balls 15a.An important aspect of this embodiment is, in turn, to reduce the surface pressure between the transmission bodies 15 and the grooves 53 of the shoulder ring 14b. This is done by matching the cross sections of the radial grooves 53 as mentioned to the cross sections of the transfer bodies 15, such as the transfer balls 15a proposed here. The grooves 53 form a wear-reducing means which has a favourable effect on the service life of the safety element.A further advantage is also shown here if the safety element 5 ais switched between the engaged and the disengaged state. In the first exemplary embodiment, this can be associated with adjacent transfer balls 15 achange their distance from one another. In general, in all the embodiments, in the uncoupled state, the distance between the transfer balls 15a is the greatest. Without lateral guidance by grooves 53, transfer balls 15a may possibly and disadvantageously move towards or away from each other in the circumferential direction. This can be avoided by means of a guidance through the proposed radial grooves 53 of FIG. 7.With reference to FIG. 8, a further measure is proposed which relates to a changed axially movable pressure body and contributes to a means for reducing wear. The movable pressing body may replace the movable pressing body 41 of the first illustrated embodiment, or it may be used, for example, in a safety member 5a in combination with the grooved plunger 9a. The axially movable pressure body is configured annularly as a pressure ring 41 aand has wear-reducing radial grooves 51, the cross section of which is likewise adapted to the shape of the transmission bodies 15, here transmission balls 15 a. In the grooves 51, the surface pressure relative to the transmission body 15 is reduced in turn and the means for reducing wear is thus provided. In order to be able to combine the pressure ring 41 awith the groove tappet 9 b, the pressure ring has radial grooves 51 in congruent arrangement, so that in pairs a respective groove 53 of the groove tappet 9 band a respective groove 51 of the pressure ring can act as a common guide for the transmission body 15.With reference to FIG. 9, a further measure is proposed which relates to a changed static pressure body. The static pressure body may replace the static pressure body 40 of the first embodiment or it may be used in a safety element 5a in combination with the grooved plunger 9b of Fig. 7 and or with the movable pressure ring 41a of Fig. 8. The static pressure body of FIG. 9 is configured annularly as a pressure ring 40 aand has radial grooves 52, the cross section of which is likewise adapted to the shape of the transfer bodies 15, here again the transfer balls 15 a. For a combination with the groove tappet 9 band / or with the pressure ring 41 aof FIG. 8, the pressure ring 40 ahas the radial grooves 52 likewise in congruent arrangement. Thus, in pairs, a respective groove 53 of the groove tappet 9 band / or a respective groove 51 of the movable pressure ring can cooperate with a respective groove 52 of the static pressure ring 40 a. Common guides for the transmission bodies 15 are obtained.List of reference characters1 Coupling 2 Coupling element 3 Coupling element 4 Axis of rotation 5 a Sicherheits element 5 b Sicherheits element 6 a Mittelachse axis 7 Mounting plane 8 Mounting plane 9 Plunger 9 b Rillen plunger 10 Housing 10 a Gehäuse edge 10 b Stirnseite end 10 c End (with housing opening) 11 Snap-in ball 12 Snap-in region 13 Adjusting screw 14 Shoulder element 14 a Ring 14 b Ring 15 Transmission body 15 a Ball 16 zyl. Resting surface 16 aSecond functional surface 17 Pin end (plunger) 18 Fastening and adjusting means 19 External thread 20 zyl. Side wall (housing) 21 Internal thread 22 Spring device 23 Disk spring element 24 Means 25 Threaded pin 26 Bore 27 Intermediate piece 28 Engagement region element 29 Engagement depression 30 Inner surface 31 Protruding collar 32 Threaded pin 33 Pin bore 34 Guide bushing 35 zyl. Inner surface 36 is cyl. Inner surface 37 Conical inner surface 38 Shaft sealing ring 39 Sealing lip 40 Pressure ring (stationary) 40 aPressing ring (stationary) 41 Pressure ring (movable) 41 aPressing ring (movable) 42 First functional surface 42 a Hohl 43 Closure element 44 zyl. Inner wall 45 Internal thread (housing 10) 46 External thread (closure element) 47 Blind bore 48 Intermediate piece (aluminum) 49 Action surface 51 Groove 52 Groove 53 Groove L1 Bearing opening L2 Bearing opening S1 Sealing ring S2 Sealing ringReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 2010 / 0224713 A1 [0004, 0013]DE 10 2019 110 297 B3 [0005, 0013]

Claims

Safety element (5a) with self-restoring property for a clutch (1) comprising two clutch elements (2, 3), wherein in an engaged state a torque can be transmitted between the two clutch elements (2, 3), and wherein by means of the safety element the two clutch elements (2, 3) can be switched into a disengaged state as a function of the torque and can be automatically reset into the engaged state, with the proviso that the self-restoring safety element (5a) comprises: - a plunger (9, 9b) which can be displaced in its axial direction by means of a provided bearing (L1, L2) in order to provide in the assembled state of the clutch (1) its engaged state or the disengaged state, - a latching element (11) which bears against the plunger (9, 9b), - a spring device (23), by means of which a spring force can be transmitted as far as the plunger (9, 9b) and further into the latching element (11), - wherein the plunger (9, 9b) is provided with a shoulder element (14) which projects in the radial direction on the plunger (9, 9b), - wherein at least one transmission body (15, 15a) is provided which interacts on the one hand with the shoulder element (14) and furthermore with at least one pressure body (40, 41, 40a, 41a), - for which the pressure body (40, 41, 40a, 41a) has a deflection surface and the shoulder element (14) comprises two functional surfaces (16a, 42), namely an inclined surface (42a) and a laterally arranged resting surface (16), - wherein the transmission body (15, 15a) in the coupled state of the clutch (1) is in contact with the inclined surface (42a) of the shoulder element (14) so as to transmit the spring force, while in the uncoupled state of the clutch (1) it bears against the lateral resting surface (16) of the shoulder element (14), and with the further proviso that in the assembled state the plunger (9, 9b) and the latching element (11) are associated with a first of the two clutch elements (2) of the clutch (1), and that the other second clutch element (3) is associated with a latching region (12) which is formed in a complementary manner to the latching element (11), -characterized in that the resting surface (16) of the shoulder element (14) of the plunger (9, 9b) is further developed with an action surface (49) which has an inclination relative to the axial direction of the plunger (9, 9b), namely, it is inclined by an angle (α) with respect to the axial direction of the plunger (9, 9b).The safety element (5a) according to claim 1, characterized in that the angle (α) of the inclination of the resting surface (16) of the shoulder element (14) is in a range from 3° to 12°, preferably in a range from 5° to 10° and particularly preferably in a range from 7° to 8°.Safety element (5a) according to claim 1 or 2, characterised in that a first axially movable pressure body (41, 41a) and a second pressure body (40, 40a) are provided, and in that the second pressure body (40, 40a) is arranged fixed relative to the housing (10).Safety element (5a) according to Claim 3, characterized in that both pressure bodies (40, 41, 40a, 41a) are spring-loaded, in that at least one of the two pressure bodies (40, 41, 40a, 41a) has an inclined deflecting surface, in that each of the deflecting surfaces is in contact with the transmission body (15, 15a), and in that at least the deflecting surface of one of the two pressure bodies (41, 41a) is arranged inclined at an angle with respect to a radial plane.The safety element (5a) according to any one of claims 1 to 4, characterized in that the bearing (L1, L2) of the plunger (9, 9b) is integrated into the housing (10), and in that the housing (10) comprises a fastening means (18) which is configured for the purpose of simple mounting of the safety element (5a) on a coupling element (2).Safety element (5a) according to one of claims 1 to 5, characterised in that the housing (10) is provided with an adjusting means (18), by means of which in the mounted state its axial position relative to the supporting coupling element (2) can be adjusted.The safety element (5a) according to any one of claims 1 to 6, characterized in that the latching region (12) is formed as an exchangeable latching region element (28), which has a fixed positioning aid (31), wherein the positioning aid (31) cooperates with a stop means of the relevant coupling element (3) in the assembled state.Safety element (5a) according to one of Claims 1 to 7, characterized in that a guide bush (34) is assigned, which in the assembled state serves for guiding the plunger (9, 9b) and / or for guiding the latching element (11), wherein the guide bush (34) is likewise assigned to the first coupling element (2) concentrically with respect to the plunger (9, 9b).Safety element (5a) according to claim 8, characterised in that the guide bush (34) is assigned as a separate component or is assigned as an integral component of the safety element (5a), for example is assigned to a housing part (10).Safety element (5a) according to one of Claims 5 to 9, characterized in that the housing (10) has a closure element (43) as the housing part, in that the closure element (43) acts as a counter bearing for the spring device (23) and / or acts as a guide for the plunger (9, 9b) and / or the latching element (11).Safety element (5a) according to claims 5 to 10, characterised in that the closure element (43) comprises a means by means of which its axial position relative to the housing (10) is adjustable.Safety element (5a) according to one of Claims 1 to 11, characterized in that the spring device comprises at least one disk spring, preferably a disk spring pack (23) consisting of a plurality of disk springs.Safety element (5a) according to one of Claims 1 to 12, characterized in that the tappet (9, 9b) and / or at least one of the pressure bodies is provided on its deflection surface with at least one radially running groove (51, 52), which in the assembled state acts as a guide for the transmission body (15, 15a).Safety element (5a) according to one of Claims 1 to 13, characterized in that the latching element (11) and / or the latching-region element (28) is produced from a ceramic material.The safety element (5a) according to any one of claims 1 to 14, characterized in that the pressure body (40, 41, 40a, 41a) and / or the transmission body (15, 15a) is made of a ceramic material.Safety element (5a) according to one of Claims 1 to 15, characterized in that the plunger (9, 9b) is to be composed of a plunger shank and a shoulder element which can be connected thereto.Clutch (1) comprising two clutch elements (2, 3) which can be rotated about an axis (4) and which can be switched into an engaged state and into a disengaged state, wherein a torque can be transmitted in the engaged state, wherein a plurality of safety elements (5a) according to one of Claims 1 to 16 are arranged on one of the clutch elements (2, 3) on a defined diameter and concentrically with respect to the axis of rotation (4) of the clutch element (2, 3), and wherein a corresponding number of engagement region elements (28) are arranged on the second clutch element (2) on an identical diameter and concentrically with respect to the axis of rotation (4) thereof, namely at congruent spacings as the safety elements (5a).Clutch (1) according to Claim 17, characterized in that a circumferential groove is provided on the second clutch element (3), which groove interacts with the latching elements (11) of the safety elements (5a) in the uncoupled state.

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