Apparatus for producing a frictional and/or form-fitting connection between two components which are arranged such that they can be moved linearly or rotated relative to one another

An apparatus is disclosed for producing a frictional and/or form-fitting connection between first and second components which are linearly or rotationally movable relative to one another for transmitting forces and/or force moments that act between the first and second components in a linear and/or rotational manner. The first component surrounds the second component, at least sectionally, with at least one inner wall that faces the second component. The second component features at least one active-face element that can be transferred in a force-loaded manner from a first position, in which the active-face element is spaced apart from the inner wall, into a second position, in which the active-face element produces the frictional and/or form-fitting connection with the inner wall. The invention includes at least one mechanical stressing element for exerting a restoring force upon the active-face element which holds the active-face element in a first position, and a kinematic system acts upon the active-face element opposite to the restoring force and is driven exclusively by a converter material, with the kinematic system transferring the active-face element into the second position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention pertains to an apparatus for producing a frictional and/or form-fitting connection between two components that are arranged such that they can be moved linearly or rotated relative to one another for the purpose of transmitting forces and/or force moments that act between the two components in a linear and/or rotational manner, wherein the first component surrounds the second component at least sectionally with at least one inner wall that faces the second component, and wherein the second component features at least one active-face element that can be transferred in a force-loaded manner from a first position, in which the active-face element is spaced apart from the inner wall, into a second position, in which the active-face element produces the frictional and/or form-fitting connection with the inner wall. An apparatus of this type is preferably used as a brake or a clutch.

As a supplement, an alternative apparatus is described that is comparable to the aforementioned apparatus and comprises two components that are arranged such that they can be independently rotated about a common rotational axis and functionally connected for the purpose of transmitting forces and/or force moments that act between the two components in a rotational manner, wherein the first component features at least one active face that is inclined relative to the rotational axis or orthogonally intersects the rotational axis, and wherein the second component features at least one active face such that a face contact between the two active faces, which results in a frictional and/or form-fitting connection between the two components, can be produced by means of an axial excursion of at least one of the two active faces. An apparatus of this type is used as a clutch element, by means of which both components can be transferred from a state of independent rotation into a state of synchronous rotation.

2. Description of the Prior Art

Apparatuses of the above-described type primarily serve for the controlled transmission of forces between two components that are usually arranged such that they can be rotated relative to one another about a common rotational axis, wherein one component is connected to a drive element and the other component is connected to a driven element. Depending on the respective technical application, the components that are functionally connected to one another in the form of a frictional and/or form-fitting connection may either serve for exerting a braking effect upon a component that serves as the drive element by the other component that serves as the driven element or, if realized in the form of a clutch, for transferring the components that respectively rotate about a common rotational axis independently of one another into a state of synchronous rotation.

One classic example for the realization in the form of a brake is the conventional drum brake, in which two shaped brake shoes are provided that can be respectively pivoted about a pivoting axis on a rigid end support, wherein the radially outer contour of said brake shoes can be respectively inscribed in a circle, and wherein the brake shoes are pivoted radially outward about the pivoting axis under the influence of an actuator such that they are pressed against the inner side of a drum-shaped housing that is connected, for example, to a wheel to be decelerated in a rotationally rigid fashion. The actuator is usually realized in the form of a hydraulic cylinder, the actuation of which causes the shaped brake shoes to be spread radially outward. After the actuation of the brake cylinders, the brake shoes are returned radially inward, that is, into a state in which they are spaced apart from the drum housing, by means of a pull-back spring.

In order to initiate a braking maneuver, it is typically required to actuate a master cylinder that is able to spread the brake shoes provided in the drum brake against the respective inner side of the drum housing in a force-loaded manner by means of a corresponding hydraulic transmission of forces.

In numerous technical applications, it is desirable to carry out certain mechanical coupling or braking maneuvers in a controlled fashion depending on, for example, the temperature and/or other external energy states. The activation of such braking or coupling maneuvers usually requires the supply of external energy, for example, in the form of mechanical energy such as, for example, the above-described actuation of a control or brake lever or in the form of electric energy such as, for example, an electric excitation of a coil such that the complexity of the braking or coupling apparatus is ultimately increased.

U.S. Pat. No. 4,550,695 describes a fan arrangement, the motor-driven fan wheel of which is held in a decelerated position by a spring brake. One side of the spring brake is rigidly connected to a stationary housing and the other side presses against a brake rotor that is connected to the fan wheel in a rotationally rigid fashion by means of a brake element that is subjected to a spring force. As long as a certain limit temperature is not exceeded, the fan wheel is stopped due to the intimate contact between the brake element and the brake rotor. Once a certain limit temperature is exceeded, the spring force is lowered such that the brake element is transferred into a position, in which it is spaced apart from the brake rotor and the fan wheel is released such that it is able to rotate freely. The spring element that is functionally connected to the brake element consists of a shape memory alloy that assumes an elongated state at low temperatures and a shortened state at temperatures above a certain limit temperature. The braking apparatus described in the aforementioned publication therefore is autonomously activated by the ambient temperature.

JP 62147130 A describes an overload clutch that is designed like a drum brake and features inner brake shoe members within a drum housing, wherein the brake shoe members are subjected to a centrifugal force resulting from the rotational movement and radially pressed against the inner wall of the drum housing by this centrifugal force. The brake shoes are also functionally connected to a spring that consists of a shape memory alloy and is shortened in case of thermal overheating due to increased brake friction such that the spring pulls the brake shoe members radially inward and the braking effect diminishes in order to ultimately prevent thermal overheating of the apparatus that acts as a clutch.

JP 61099724 A describes a clutch arranged between a drive segment and a driven segment, wherein a coil spring is extended and relaxed by a spring consisting of shape memory material such that the drive shaft and the driven shaft are respectively engaged and disengaged. The spring consisting of shape memory material is subjected to an electric control current in order to actuate the clutch.

Japanese publication JP 58211027 A also describes a mechanism that increases the braking force between two rotating bodies and, analogous to the initially cited design of a drum brake, features two shaped brake shoes that are respectively adapted to the inner contour of the drum housing and can be pivoted radially outward against the wall of the drum housing about a common rotational axis. The excursion of the brake shoes about the rotational axis is realized with the aid of an externally actuated hydraulic cylinder that makes it possible to bring the brake shoes into intimate frictional contact with the inner wall of the drum housing. The rotation of the inner wall of the drum relative to the brake shoes generates frictional heat that is able to spread a functional element that consists of shape memory metal and is also connected to the brake shoes such that the braking force between the brake shoes and the inner wall of the drum housing is increased.

SUMMARY OF THE INVENTION

The invention is an apparatus of the initially described type for producing a frictional and/or form-fitting connection between two components that are arranged such that they can be moved linearly or rotated relative to one another in such a way that the transmission of rotationally or linearly accelerating or decelerating forces or force moments between a rotatable or linearly movable component relative to a second component can be realized with the simplest construction possible, wherein the engaging or coupling process, during which both components are respectively engaged or functionally connected to one another, takes place automatically, that is, without controlling an external energy supply. The activation of the engaging or coupling process should rather be initiated automatically in dependence on an energy state that is adjusted in an uncontrolled or unregulated fashion such as, for example, the ambient temperature. In addition, it should not only be possible to realize the activation in dependence on thermal energy, but also in dependence on other types of energy such as, for example, magnetic or electrodynamic energy.

The invention is an apparatus for producing a frictional and/or form-fitting connection between two components that are arranged such that they can be moved linearly or rotated relative to one another for the purpose of transmitting forces and/or force moments that act between the two components in a linear and/or rotational manner, wherein the first component surrounds the second component at least sectionally with at least one inner wall that faces the second component, and wherein the second component features at least one active-face element that can be transferred in a force-loaded manner from a first position, in which the active-face element is spaced apart from the inner wall, into a second position, in which the active-face element produces the frictional and/or form-fitting connection with the inner wall, with the apparatus being realized in such a way that at least one mechanical stressing element is provided that exerts a restoring force upon the active-face element and this restoring force holds the active-face element in a first position. In addition, a kinematic system is provided that acts upon the active-face element opposite to the restoring force and is driven exclusively by a converter material, wherein the kinematic system transfers the active-face element into the second position.

According to the invention, the kinematic system, driven by a converter material, initiates a coupling or braking process between both components, as well as the at least one mechanical stressing element for kinematically decoupling the two components from one another, is directly connected to the second component or forms part of the second component such that, if the first component is a drum housing, the at least one stressing element, as well as the kinematic system, preferably can be peripherally surrounded by the drum housing in its entirety in order to create a completely encapsulated unit without any external connection. Depending on the material class selection with respect to the converter material that drives the kinematic system, it needs to be ensured that the energy form that activates the converter material is also able to act within the space encapsulated by the first component, in which the converter material and the stressing element are situated. In addition to the basic usability of piezoelectric materials, electrorestrictive materials and magnetostrictive materials are possible converter materials. Also, a shape memory alloy (SMA) that is subjected to a predetermined shape change as the temperature changes is also particularly suitable for this purpose. Shape memory alloys in the form of wires or strips are typically reduced in length when an activation temperature that depends on the particular alloy is exceeded, wherein length reduction causes the excursion of the active-face elements into the above-described second position due to the corresponding design of the kinematic system. Consequently, it needs to be ensured that the converter material is thermally coupled to the ambient temperature. Corresponding precautions need to be taken if the converter material consists, for example, of a magnetostrictive material that undergoes a shape change due to a variation of the magnetic field surrounding the converter material.

The inventive apparatus serves as a clutch or a brake depending on whether both components can be rotated about a common rotational axis independently of one another or one of the two components is arranged stationarily in space. In both instances, a corresponding excursion of the at least one active-face element against the inner wall of the first component results in forces that act radially referred to the rotational axis and cause the coupling or braking process between both components. As an alternative to such an apparatus, it is also possible realize another brake or clutch apparatus that operates in an entirely autonomous or free fashion and comprises two components that are arranged such that they can be independently rotated about a common rotational axis, wherein the first component features at least one active face that is inclined relative to the rotational axis or orthogonally intersects the rotational axis, and wherein the second component features at least one active face such that a face contact between the two active faces, which results in a frictional and/or form-fitting connection between the two components, can be produced by means of an axial excursion of at least one of the two active faces. The forces and/or force moments acting between both components are directed axially referred to the rotational axis in this variation. In the case, a converter material for generating a first axially directed force, as well as a spring-like element for generating a second directional force that is directed axially opposite to the first force, is also provided on one of the two components. The converter material and the spring-like element are placed between two parts of the one component that can be axially moved relative to one another and are connected in a rotationally rigid fashion such that they are able to axially move both parts in dependence on the shape change of the converter material used. Since the second variation features two components that are arranged such that they can be rotated along a common rotational axis independently of one another, this variation serves exclusively as a clutch element and, analogous to the first alternative, is advantageously an extremely compact and robust construction that is furthermore able to operate without any externally regulated or controlled energy supply. However, this apparatus may also serve as a brake if one component is coupled stationarily in space.

As initially mentioned, the inventive apparatus may, depending on the respective design, serve as a brake or a clutch between two rotating shafts, one of which represents, for example, a drive shaft and the other one of which represents a driven shaft. The inventive apparatus is particularly suitable for kinematically coupling a fan propeller to a shaft that is driven by an electric motor. In this case, the objective is operating a fan propeller that usually is rigidly connected to such a shaft and always rotates synchronous with the shaft speed due to the rigid connection to the shaft in such a way that the fan propeller only rotates synchronously with the shaft if a cooling effect to be realized with the fan propeller is desired due to the current heat state. Under normal operating conditions, such a cooling effect is only realized at extreme ambient temperatures and a correspondingly extreme load of the electric motor such that the fan propeller can be mostly switched off, for example, in order to reduce the noise. The inventive clutch apparatus makes it possible, for example, to only drive the fan propeller that is rigidly connected to the first component by the drive shaft connected to the second component if an ambient temperature that causes the initial deformation of the converter material is exceeded. If the ambient temperature remains below the corresponding limit temperature, no accelerating forces of the drive shaft whatsoever are transmitted between the second and the first component.

Based on the functional principles for coupling two components that can be rotated relative to one another or two components that can be moved linearly to one another which were generally described above, it is possible to realize several concrete embodiments, based on which the general principle of the invention is described in greater detail below.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a first embodiment of an inventive apparatus that makes it possible to transmit rotational forces or force moments between two components1and2that are arranged such that they can be rotated about a rotational axis D. It is assumed that the second component2is arranged on a drive shaft3in a rotationally rigid fashion while the first component1is a hollow-cylindrical component or a drum housing and connected to a driven element which is not illustrated. The second component2that is connected to the shaft3features a disk-shaped carrier plate2′, wherein two sickle-shaped or arc-shaped active-face elements4and5are coupled to the upper side of the carrier plate that faces the observer inFIG. 1such that they can be respectively pivoted about a pivoting axis D1and D2. On the side that radially faces away from the shaft3, the active-face elements4and5have a surface contour that is largely adapted to the inner wall1′ of the first component1which is a hollow-cylindrical drum housing in a form-fitting fashion. A friction lining6is provided at least in a selected region of the surface of the respective active-face element4and5that faces the inner wall1′ of the drum housing, wherein the friction lining makes it possible to generate higher frictional forces between the respective active-face elements4and5and the inner wall1′ of the first component1that is realized with a drum housing.

The ends of the active-face elements4and5that lie opposite of the pivoting axes D1and D2, are connected to one another by a mechanical stressing element7which is a conventional tension spring in the embodiment according toFIG. 1such that the stressing element7holds both active-face elements together as shown inFIG. 1if no other forces act upon the active-face elements4and5and the surfaces of the active-face elements4and5that face the inner wall of the first component1and, in particular, the friction linings6are radially spaced apart from the inner wall of the first component1. In addition, web-like extensions8and9are arranged on both active-face elements4and5in the manner shown inFIG. 1, wherein these web-like extensions respectively extend in the direction of the opposite active-face element and both web-like extensions8and9overlap one another at least sectionally. A wire-shaped or strip-shaped converter material, preferably in the form of a SMA wire, that is, a wire made of a shape memory material or shape memory alloy, which extends between the two web-like extensions8and9, wherein the converter material is subjected to such a shape change under the influence of energy in the form of heat that it contracts in the longitudinal direction under an elevated temperature. This generates a force that is directed opposite to the prevailing restoring force exerted by the stressing element7and spreads both active-face elements4and5radially outward such that the friction linings6of the active-face elements4,5are pressed into frictional engagement with the inner wall1′ of the first component1which is a drum housing. Depending on whether the first component1that is connected to the driven element is also able to rotate about the rotational axis D or arranged stationarily, the prevailing rotational movement caused by the drive shaft3can be transmitted to the first component1or decelerated accordingly by means of the second component2. However, once the temperature drops below a certain temperature value, the SMA wire relaxes again and the stressing element7which is a conventional tension spring or coil spring, pulls the active-face elements4and5, which act as brake shoes, together such that the frictional connection is disengaged. The tension spring or coil spring used as the stressing element7needs to have a spring stiffness such that it not only holds together the active-face elements4and5against the centrifugal forces acting thereupon, namely even at the highest occurring rotational speeds of the second component about the rotational axis D, but can also be extended by the SMA wire10and the outwardly directed force that is generated when this wire is heated and radially acts upon the active-face elements4and5.

According to the embodiment shown inFIG. 1, only the stressing element7that is functionally connected to the active-face elements4and5and the wire-shaped or strip-shaped converter material10are required for producing and for disengaging the frictional connection between the first and the second component. This means that no other regulated or controlled external energy supply is required for producing and disengaging the frictional connection and/or form-fitting connection between the two components1and2. The frictional and/or form-fitting connection is simply produced and disengaged by utilizing the energy state that is able to cause a corresponding shape change in the converter material10. Depending on the selection of the converter material, the function of the inventive apparatus may depend on a prevailing external energy field. If the converter material is a temperature-sensitive material as described above, for example, a shape memory alloy, the shape of the converter material is usually reduced in size or shortened beginning at a certain limit temperature, wherein the converter material is reversibly returned to its original shape by means of an external force or spring force when the temperature drops below the limit temperature.

However, it is also possible to utilize converter materials such as, for example, magnetostrictive materials that are subjected to a shape change when the intensity of the surrounding magnetic field changes. Other converter materials such as, for example, piezoelectric or electrorestrictive materials are able to perform shape changes that can be initiated by applying an electric voltage or an electrostatic field.

The compactness and, in particular, the mechanical encapsulation of the system for realizing a braking effect and for terminating a braking effect achieved due to a free engaging principle is illustrated in the embodiment according toFIG. 1. If the first component is a drum housing with at least one open drum housing side for installing the active-face elements4and5connected to the second component such that a closed, encapsulated brake or clutch element to be implemented between a drive train and a driven train can be realized, rotationally acting forces or force moments can be transmitted between both components in dependence on a prevailing external energy field if the drive element and the driven element are rotating elements.

It is also possible to transmit linear forces between the two components if the first component can be longitudinally displaced relative to the second component along the linear axis that is identified as the rotational axis D inFIG. 1. This would be the case, for example, if the first component1is realized as an elongated hollow-cylindrical tube, in which the second component2can be longitudinally displaced. If the length of the converter material10is shortened in this case, a frictional connection is produced between the friction linings6of the active-face elements4and5and the inner wall1′ of the first component1such that a linear transmission of forces can be between the two components. If a purely linear transmission of forces is required between the two components, it would naturally also be possible to choose a cross-sectional shape other than circular, for example, rectangular or n-angular, for the inside contour of the inner wall1′ of the first component, wherein the correspondingly counter-contoured active-face elements4and5that are on the second component2such that they can be rotated or linearly moved in the form of a restricted guidance to produce a frictionally engaged connection to carry out an excursion relative to the aforementioned inner wall of the first component.

The friction lining6illustrated inFIG. 1primarily serves for increasing the frictional forces that can be generated between the friction lining6and the inner wall1′ of the first component so as to produce a frictionally engaged connection. The inner wall1′ of the first component1, as well as the active faces of the active-face elements4,5that can be functionally connected thereto, may be advantageously realized structured or counter-structured referred to the inner wall1′ in order to also produce a form-fitting connection in addition to a frictional connection.

FIGS. 2 to 4show equivalently acting mechanisms that are based on the same functional principle as the clutch or brake apparatus according toFIG. 1between a drive shaft and a driven shaft which can be distinguished with respect to their kinematic drive system. Analogous toFIG. 1, the active-face elements4and5inFIG. 2are coupled to the second component2such that they can be respectively rotated about the axes D1and D2independently of one another in the form of a restricted guidance. In this case, a conventional tension spring7on the respective ends of the active-face elements4and5that lie opposite of the axes D1and D2also ensures a restoring force directed radially inward and acting between only the active-face elements4and5. In order to spread the active-face elements4and5radially outward against the inner wall1′ of the first component1, a toggle lever mechanism11with two levers13and14that can be respectively pivoted relative to one another by means of a pivot joint12is additionally provided at the coupling points of the tension spring7. A deviating link15of circular design is furthermore provided on the pivot joint12, wherein a wire-shaped or strip-shaped converter material10that preferably is a SMA material extends over the deviating link and is rigidly connected on both sides to the respective coupling points of the active-face elements4and5. Due to the constructive design of the toggle lever mechanism11in connection with the wire-shaped converter material10according to the embodiment shown inFIG. 2, the SMA wire10is shortened when heated such that the toggle lever11is spread apart and the active-face elements4and5are pressed radially outward against the inner wall1′ of the first component1. The deviating link15allows the utilization of the longest SMA wire possible in order to increase the percentile change of the length of the converter material and therefore ultimately increases the force that is directed radially outward and acts between the active-face elements4and5.

InFIG. 3, the active-face elements4and5, that are connected to the second component2analogous to the above-described embodiments, are rotatably coupled to the respective rotational axes D1and D2in a restricted guidance. The opposite ends of the active-face elements4and5respectively feature face sides16and17that are spaced apart from one another by a gap and produce a sliding functional connection with an oval-shaped cam18that can be rotated about a rotational axis D3located in the intermediate space between the face sides16and17. The cam18is connected to a lever arm18′, to one side of which a wire-shaped or strip-shaped converter material10is coupled, that is connected to the second component2which is an end support. The other side of the lever18′ is connected to a stressing element7which is a conventional tension spring that is connected to the second component2and the spring characteristic of which is adjusted such that the cam18is spaced apart from both face sides16and17symmetrical to the rotational axis D3in an initial position. If the converter material10is a SMA element, the SMA element is shortened as the temperature increases so that a force, that is directed opposite to the spring force, is generated by the SMA element, which causes the lever arm18′ to extent. This causes the cam18to press both face sides16and17in two opposite directions in accordance with its outside contour such that the active-face elements4are5are displaced radially outward due to their rotation about the respective rotational axes D1and D2and produce a frictionally engaged connection with the inner wall1′ of the first component in the above-described fashion. Once the temperature drops again, the wire-shaped or strip-shaped converter material10can be returned to its original shape under the influence of a mechanical stressing force, for example, a spring force, such that it reassumes the neutral position illustrated inFIG. 3.

FIG. 4shows another variation for producing a frictional or form-fitting connection between a second component2that is connected to a drive shaft3and the inner wall1′ of a first component1. As in the above-described embodiments, the second component2also features a carrier plate19that is connected to the drive shaft3in a rotationally rigid fashion, wherein lever-like active-face elements4′ are coupled to the carrier plate such that they are rotatable about a rotational axis20and feature friction linings6that face the inner wall1′ of the first component1. In order to subject the friction linings6to a radial excursion in the direction of the inner wall1′ of the first component1, the lever-like active-face elements4′ are about centrally connected to an adjusting lever21with the other side being rotatably connected to a second carrier disk22that is decoupled from the rotation defined by the shaft3and therefore from the carrier disk19by a bearing23. The carrier disk22is connected to a conventional tension spring7and the wire-shaped or strip-shaped converter material10at two coupling points that lie diametrically opposite of one another on its disk periphery. The tension spring and the converter material10are coupled to one side of the carrier disk19with end supports. The bearing23makes it possible to rotate the carrier disk22relative to the carrier disk19. If the first and the second components are in the decoupled state, the forces engaging on the carrier plate22by means of the converter material10and the tension spring7are adjusted in a balanced manner so that the friction linings6are spaced apart from the inner wall1′ of the first component1. However, once a certain limit temperature is exceeded, the length of the converter material10is reduced such that the carrier disk22is turned relative to the carrier disk19, namely in the counterclockwise direction in the embodiment shown inFIG. 4. This rotation results in an extension of the adjusting lever that is coupled to the carrier disk22and ultimately presses the active-face element4′ which is a rod-shaped lever with a friction lining6arranged thereon against the inner wall1′ of the first component1. Once the ambient temperature drops accordingly, it is possible to extend the converter material10under the influence of the tension generated by the tension spring7such that the carrier plate22can be turned back into the initial position illustrated inFIG. 4. According to the embodiments shown, three such active-face elements that can be subjected to a lever-like extension are provided. However, this number may vary and depends on the shape and size of the disk arrangement and the lever arrangement.

The embodiments illustrated inFIGS. 5,6and7show clutch or brake apparatuses, in which the forces generated between two components are oriented axially rather than radially (referred to an axis of a rotary drive as above) wherein these clutch or brake apparatuses are also based on the activation of a correspondingly designed converter material as in the previously described embodiments.

The apparatus illustrated inFIG. 5features a first component1that surrounds the face side of a drive shaft3similar to a sleeve, wherein the first component1is rotationally decoupled from the rotation of the drive shaft3by means of a bearing, preferably a needle bearing25. The second component2is connected to the shaft3in a rotationally rigid fashion and features a first carrier plate24, to the peripheral edge of which a second carrier plate24′ is coupled in a rotationally rigid fashion, however, such that it can be axially displaced relative to the first carrier plate24. A pressure spring7and a wire-shaped or strip-shaped converter material10are respectively provided between both carrier plates24and24′ in order to realize the axial excursion of the second carrier plates24′. According to the embodiment shown inFIG. 5, the sleeve-like first component1features a disk-like widening1′, on which axially opposite sides of friction linings6are arranged. The first and the second carrier plates24and24′ of the second component2also feature surface areas that face the disk-like widening of the first component1and also feature friction linings6that are able to produce a frictionally engaged connection with the friction linings6of the first component1if they are subjected to a corresponding axial excursion.

In an initial state, the stressing element7which is a conventional pressure spring ensures that the first and the second component are spaced apart such that the corresponding friction linings6are not frictionally engaged. However, once a certain limited temperature is exceeded, the length of the wire-shaped or strip-shaped converter material10extending between the first carrier plate24and the second carrier plate24′ is reduced such that the corresponding friction linings6are axially pressed against one another and the first and the second component are rotationally coupled.

FIG. 6shows another embodiment, in which the first component1is connected to a driven element which is not illustrated and is axially seated on the drive shaft3such that it is rotationally decoupled by means of a radial bearing25. The second component2is rigidly connected to the drive shaft3and features a first carrier plate24that is connected to a second carrier plate24′ which is arranged in the first carrier plate24in a rotationally rigid fashion by means of a combination of a pressure spring7and a converter material10that are analogous to the embodiment shown inFIG. 5. The second carrier plate24′ is once again connected to the first component1by means of a radial bearing26, wherein the radial bearing26is only able to transmit axially directed forces to the first component1. In addition, the face side of the drive shaft3has a contour27that is similar to a truncated cone and features an active face28that is directed obliquely to the shaft axis. A corresponding opposite active face29is provided on the first component1axially opposite of the active face28such that a frictionally engaged connection is produced between the shaft drive3and the first component1when both active faces come in contact with one another. Once a limit temperature for the converter material10is exceeded, the converter material contracts such that the second carrier plate24′ is subjected to an axial excursion in the direction of the first carrier plate24. The radial bearing26transmits the axial excursion to the first component1with the corresponding opposite active face29being pressed against the active face28of the contour27in the shape of a truncated cone in a force-loaded fashion and causes a certain braking effect. Once the temperature drops below a certain limit temperature that is defined by the converter material, the axial distance between the first and the second carrier plates24and24′ increases due to the force generated by the pressure spring7such that the active faces28and29are axially spread apart.

FIG. 7shows a combined illustration of two apparatuses along a common rotating shaft3. Both brake or clutch variations which are shown also feature a sleeve-like first component1that is axially seated on the drive shaft3by means of a radial bearing25and, for example, may be connected to a driven element analogous to the above-described embodiments shown inFIGS. 5 and 6. The second component2is arranged along the drive shaft3and has the following components. A supporting plate30that is connected to the shaft3in a rotationally rigid fashion, a sliding ring31that is arranged along the drive shaft3in a rotationally rigid, but in an axially displaceable fashion, a stressing element which is a conventional tension spring7that is provided between the sliding ring31and the supporting plate30, as well as a wire-shaped or strip-shaped converter material10that is also provided between these components, a first friction element32that radially protrudes from the drive shaft3and is connected to the drive shaft3in a rotationally and axially rigid fashion, as well as a second friction element33that is arranged on the drive shaft3in a rotationally rigid, but axially in displaceable fashion, wherein both friction elements32are33are axially spaced apart from one another and enclose an intermediate space, into which a third friction element34that is rigidly connected to the first component1protrudes from the side of the first component. The second friction element33, which can be axially displaced relative to the drive shaft3, produces a functional connection with a toggle lever35that can be pivoted about a pivoting axis D and is connected to the drive shaft3. An extension of the toggle lever35about the pivoting axis D occurs when the toggle lever35comes in contact with a sliding ring surface36that is directed obliquely to the shaft axis as shown in the upper illustration ofFIG. 7. In this embodiment, the converter material is coiled in a spiral-like fashion and is able to deform in such a way when a certain limit temperature is exceeded that the spiral of the converter material is elongated along its spiral axis. In the upper variation ofFIG. 7, an axial displacement of the sliding ring31in the direction of the first component1occurs such that the toggle lever35is pivoted about the pivoting axis D in such a way that the second friction element33is axially pressed against the third friction element34and a corresponding frictionally engaged connection with the axially fixed first friction element32is produced. Once the temperature drops below the corresponding limit temperature again, the tension spring7ensures that the toggle lever35is correspondingly reset such that the intermediate space enclosed between the first and the second friction elements is increased and the third friction element34is released to run freely.

In contrast to the upper variation illustrated inFIG. 7, the lower variation features a sliding ring31, with a sliding ring surface36directed and arranged such that an axial excursion of the sliding ring31toward the first component1causes the toggle lever35to pivot so that the intermediate space between the first and the second friction element32and33is increased and the braking effect is terminated. To this and, a wire-shaped or strip-shaped converter material10is provided between the supporting plate30and the sliding ring31and shortened when heated as in the above-described embodiments. In order to return the sliding ring31into an axial initial position once the temperature drops below the corresponding limit temperature again, a conventional pressure spring7is provided between the supporting plate30that is connected to the drive shaft3in a rotationally rigid fashion and to the sliding ring31.

The embodiments described so far primarily serve for transmitting forces or force moments between two components that are arranged such that they can be rotated relative to one another. The embodiment according toFIG. 8, in contrast, serves for transmitting forces or force moments between two components that are arranged such that they can be linearly moved relative to one another. For this purpose, the first component1that serves, for example, as the driven element and is preferably connected to a stationary part features a groove-shaped recess38in its surface. The recess38has a dovetail-shaped cross section with two opposing lateral flanks39and40which are respectively directed obliquely to one another in the embodiment shown inFIG. 8. Although the recess does not necessarily have to be a dovetail, at least one lateral flank that defines the recess38should be an undercut in order to generate a corresponding clamping force toward the second component2as described below.

A second component is arranged such that it can be linearly moved relative to the first component1and is connected, for example, to a drive which is not illustrated. The second component2is sleeve-like and features two lever-like active-face elements4and5in its interior that can be pivoted about a rotational axis D and feature an active-face element end4′ and5′ that protrudes over the second component2. The active-face element ends4′ and5′ that protrude over the second component2engage into the recess38and feature active faces41and42that are arranged opposite of the active faces39and40and respectively carry a friction lining6. A conventional tension spring7is also connected to the active-face element ends4′ and5′ and is able to pull together both active-face element ends4′ and5′ relative to the rotational axis D such that the active faces41and42with the friction linings6situated thereon are spaced apart from the opposite lateral flanks39and40. A converter material10made of SMA material extends between the active-face element ends4″ and5″ that lie opposite of the active-face element ends4′ and5′ and is able to contract as the temperature increases. Due to the lever effect and the ability to rotate the individual active-face elements4and5about the corresponding rotational axes D, the active faces41and42with the friction linings6arranged thereon are pressed against the lateral flanks39and40in a force-loaded fashion which, in this case, is such that the first and the second components can be locked relative to one another.

The above-described embodiments respectively feature a first and a second component that can be respectively connected to either a drive element or a driven element. The embodiments shown inFIGS. 9aandbindicate that the inventive apparatus can be flexibly utilized. For example,FIG. 9ashows that the first component1that is usually realized as a drum housing is connected to a driven element and guided such that it can be rotated relative to a drive shaft3by means of a corresponding bearing L. The second component2is realized as a carrier plate and is connected to the shaft drive3in a rotationally rigid fashion. Active-face elements4and5coupled to the second component and can be displaced radially relative to the shaft3against the inner wall of the drum-shaped first component and therefore transmit radially acting forces or force moments to the first component.

It is also possible to connect the first component1to a shaft drive3in a rotationally rigid fashion as shown inFIG. 9band to decouple the second component2from the rotational movement of the shaft drive3by means of a bearing L. The second component2is connected to the driven element in this case.

Due to the inventive apparatus that may be realized in the form of a clutch or a brake depending on the intended use, no regulated or controlled energy supply, for example, in the form of mechanical, electrical, hydraulic or pneumatic energy other than heat that can be generated by a process, for example, in the form of the waste heat of an engine to be cooled, is required for the actuation or engagement of the apparatus if an SMA converter material is used. Consequently, it is possible to realize, in particular, temperature-dependent engagements between linearly moved or rotating parts in a simple and compact fashion that causes little wear and requires little maintenance, wherein no energy other than the heat triggering the engagement needs to be supplied. The engagement is reversible, that is, it is reversed again as soon as the temperature drops below a certain value without an external energy supply.

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