Abstract:
A door handle with a door-side output shaft  17  and a handle  10  facing away from the door, said output shaft and handle having a common rotational axis  2  and being connected via an electromechanical clutch, may be particularly compact and may have a particularly low energy intake for shifting the clutch by providing the output shaft  30  with a recess  31  on the side facing towards the handle  10 , in which a coupling element  40  is displaceably mounted; by providing the door handle  1  with a receiving area  51  for the coupling element  40  opposite to the recess; and by arranging a linear drive in the handle, the linear drive acting on the coupling element  40  in order to move the coupling element  40  in the axial direction so far out of the recess that the coupling element engages both into the recess  31  as well as into the receiving area  51  in order to close the clutch, and the coupling element is moved out of the receiving area  51  back into the recess  31  in order to open the clutch.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of pending International Application No. PCT/EP2015/055580 filed on Mar. 17, 2015 and now published as WO 2015/140180, which designates the United States and claims priority from German Application No. 10 2014 103 666.2 filed on Mar. 18, 2014. The disclosure of each of the above-identified patent documents in incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a door handle, e.g. to a doorknob, with a door-side output shaft and a handle facing away from the door leaf, wherein the output shaft and the handle have a common rotation axis and are connected by a preferably electromechanical clutch, so that with an open clutch the handle may be operated, i.e. may be rotated, without entraining the output shaft. With a closed clutch, however, the handle and the output shaft are non-rotatably connected with each other. 
         [0004]    2. Description of Relevant Art 
         [0005]    In Europe, so-called case locks are generally used in doors, which are also known as mortise locks. Mortise locks are inserted into a recess in the narrow side of the door which is revealed when opening of the door, and are fixed there. These mortise locks have a latch and usually a dead bolt (bolt, for short). At least the latch may usually be retracted by a door handle (mostly in a form of a doorknob) to open the door. In so-called anti-panic locks, also the dead bolt is coupled with the handle, such that also this bolt is retracted upon actuation of the handle. To initiate the rotational movement of the door handle in the mortise lock, the mortise lock has a so-called nut, in which usually a square shaft extending orthogonally to the door leaf is inserted, such that it protrudes at least on one side over the door leaf. The nut is thus some sort of socket for (e.g. form fittingly) receiving the shaft. The door handle is then placed on this free end in a rotationally locked manner. 
         [0006]    Locking or unlocking the door is usually done by so-called cylinder locks, which are inserted in the mortise locks. The cylinder locks have a locking cam arranged on a shaft, which cam interacts with the mortise lock. The locking cylinder allows rotation of the locking cam by a user, provided the user is authorized, whereby either a key or a knob serves for actuating the locking cam by the user. 
         [0007]    Electromechanical locking systems are based on the electronic identification of a key. The key may be, for example, an active or passive transponder. A lock control exchanges data with the key, thereby checks the authorization of the key, and possibly releases the lock. To release the lock in electromagnetic locking cylinders, the locking cam must be non-rotatably connected (i.e. coupled) with a handle, e.g. a knob. In an unreleased state, at least the handle arranged on the outside of the door is not non-rotatably connected with the locking cam (un-coupled state). For switching between the coupled and the uncoupled locking cam, a clutch (also inter-changeably referred to herein as a switchable clutch) is required. Such clutch, being switchable by the lock control, has on the one hand to be so small that it can be integrated into a locking cylinder, and on the other hand has to absorb comparatively high torques, such that even malfunctioning, e.g. sticking locks can be opened. The energy supply is mostly provided by batteries, which is why the energy requirement of the coupling for a closing and opening operation has to be minimized. 
         [0008]    In DE 198 54 454 C2, an electromechanical locking cylinder with an external knob is described, which can be non-rotatably coupled with a locking cam via an electromotively actuated clutch. For this purpose, a shaft is guided from the outside knob into an inner knob, where it carries a support for a linear drive. By means of the linear drive, a coupling element may be inserted in a recess of the hollow shaft which is as well led out from the locking cylinder shaft. The end of the hollow shaft being led out is extended in a flange-like manner and carries the inner knob. The other end of the hollow shaft carries the locking cam. 
         [0009]    DE 10 2004 056 989 A1 also describes a locking cylinder with a clutch for a non-rotatable connection of two knobs with a locking cam. The outer knob sits on a pin mounted in the locking cylinder, which pin is non-rotatably connected to a hollow shaft. A coupling gear sits non-rotatably on the hollow shaft. The coupling gear is located in the door-inner-side half of the locking cylinder and is overlapped by axially displaceable coupling claws. The coupling claws each have a radially inwardly facing locking protrusion at their distal end, which can be inserted between the teeth of the coupling gear. Thus, the claws can be non-rotatably coupled to the hollow shaft. When, in addition, the claws engage with counter-claws of a sleeve bearing the locking cam, the lock can be operated by turning the outer knob. The claws are located on an axially displaceable ring and extend from the ring towards the outside of the door. In addition, the ring is permanently non-rotatably connected to a flange bearing the inner knob. By correspondingly displacing the ring, the claws can be disengaged from the counter-claws, whereby the inner knob is decoupled from the locking cam. 
         [0010]    U.S. Pat. No. 6,460,903 B1 discloses a door lock with an inner knob and an outer knob acting on a door latch. The inner knob is permanently connected to the door latch via an output shaft, such that said door latch can be permanently retracted by a rotation of the inner knob at any time. The outside knob has a ring being non-rotatably connected to the corresponding handle with a spur toothing in which a coupling ring can be inserted by means of a slider. The coupling ring has two radially placed entraining wing parts, each having two teeth being complementary to the spur toothing. The entraining wing parts are mounted axially displaceable in two slots of a connecting element, such that a rotation of the coupling ring is transmitted to the connecting element. The connecting element has a receiving area in which the output shaft is mounted non-rotatably. 
         [0011]    U.S. Pat. No. 6,460,903 B1 also describes an electronic door lock with two knobs that act on a door latch. The inner knob permanently acts on the latch, the outer knob can be indirectly coupled to an output shaft of the inner knob. 
         [0012]    In WO 2011/119097 A1, a window handle with locking being adjustable by an electromotor is disclosed. Balls can be inserted by an axial slider in a radial direction in corresponding receiving areas of a rosette screwed to the window, thereby causing the window handle to be locked against rotation. 
         [0013]    Alternatively, also clutches are known which are arranged under a cover being arranged directly on the door leaf and serving to connect a doorknob with a nut of a mortise lock (EP 1 662 076 B1, EP 1881135 A1, EP 1522659 B, DE 10 2009 018471 A). These find, however, only limited acceptance for aesthetic reasons. 
       SUMMARY 
       [0014]    The object of the present invention is to simplify the—often perceived as cumbersome—release of the lock by means of a locking cylinder. 
         [0015]    A door handle, also called doorknob, is a lever-like device for opening and closing the latch of a door. The door handle thereby acts via a shaft, usually a square shaft, on the so-called spindle hole (referred to, shortly, as a nut) of a mortise lock (see e.g. DIN 18 251). A door handle usually has two legs: a first leg the longitudinal axis of which generally, or even preferably, coincides with the rotation axis of the nut, and a second leg attached angled thereto and acting as a lever. For actuating the door handle, the second leg is pivoted about the longitudinal axis of the first leg, rotating the first leg accordingly. Usually, the first leg is much shorter than the second leg. 
         [0016]    The door handle has a door-side output shaft and a handle facing away from the door. The output shaft may be, as usual, connected to the nut of a mortise lock via e.g. a square shaft. The handle serves to pivot the door handle about an axis of rotation. The handle serves to pivot the door handle about a rotation axis. The handle and the output shaft have a common rotation axis and are connected to one another via a preferably electro-mechanical clutch. 
         [0017]    A shifting clutch (also referred to herein as a clutch) is to be understood as a coupling which can be opened and closed. In an open state of the clutch, the handle is freely rotatable with respect to the output shaft, i.e. the door cannot be opened. In a closed state of the shifting clutch, the handle and the output shaft are non-rotatably connected to each other, so the door can be opened. The adjustment of the shifting clutch between the two states “closed” and “open” is preferably carried out electromechanically, so that a lock control can switch the clutch between the two states. 
         [0018]    Preferably, the output shaft has a recess on the side facing towards the handle, in which a coupling element is mounted preferably axially displaceable. The handle has a receiving area for receiving the coupling element, which receiving area is located preferably directly opposite to the recess. The recess, the coupling element and the receiving area are complementary to each other and are not rotationally symmetric to the rotational axis in at least one section, so that a rotation movement is transmitted from the handle to the output shaft via the coupling element, when the coupling element (more precisely, the at least one non-rotationally symmetrical section of it) engages in the complementary sections of both the recess and the receiving area. If the coupling element rotationally engages into the recess and the receiving area, the clutch is locked, and correspondingly the coupling element is in the closed-position. When the coupling element rotationally engages only in one of the receiving area and in the recess, the clutch is opened and the coupling element is in the open-position. Generally, the receiving area is also a recess of the handle. Merely for linguistic distinction between the two recesses, the term ‘receiving area’ is used. One could alternatively speak of a first recess (the recess) and a second recess (the receiving area). 
         [0019]    A linear drive is arranged in the handle, which drive acts on the coupling element to displace the coupling element in axial direction out of the recess so far that, it engages both in the recess and in the receiving area in order to thereby close the coupling. For opening of the coupling, the coupling element is displaced from the receiving area back into the recess. Such a clutch is very reliable, compact and can transmit also high torques with only little material. In addition, this clutch can be arranged in a very narrow shaft, i.e. in a narrow door-side leg of a door handle. The door handle can therefore be correspondingly slim and does not necessarily differ visually from the usual rigid door handles that do not contain a clutch. 
         [0020]    Preferably, the recess receives the coupling element completely if it is in its open position. In the closed-position of the coupling element, it is arranged preferably completely in a cavity formed by the recess and the receiving area. This allows to form the clutch particularly compact. In addition, the end faces of the output shaft and the handle preferably abut each other (thereby forming a rotation gap or a plain bearing), whereby tilting moments are introduced from the handle into the output shaft, which increases the stability of the door handle. 
         [0021]    Preferably, the output shaft is rotatably mounted in a door-side recess of the handle. This can ensure that a displacement of the coupling element is not disturbed by forces acting on the handle in a direction radial with respect to the rotation axis. For absorbing such forces, the handle is preferably rotatably mounted relative to the door leaf. For this purpose, e.g. a rosette overlapping the door-side end of the handle can be formed as a bearing for the handle. Such rosette can also be fastened (e.g. by screws) to the door leaf from the inside of the door, and can thereby complicate an attack on the clutch of the door handle mounted on the outside. With regard to an adjustment of the clutch, the rosette preferably has no function, in this regard of the door handle is autonomous. 
         [0022]    Preferably, the coupling element is pre-loaded or biased in the direction of the handle. For closing the door, it is then sufficient to release the way of the coupling element in the direction of receiving area. Once the output shaft and the handle are correspondingly aligned to each other, the coupling element is displaced such that it engages in the receiving area and in the recess. The clutch is now closed. For opening of the shifting clutch, the coupling element is moved out of the receiving area, whereby the pre-load (a bias) is increased again. For biasing, a biasing spring, e.g. a coil spring, may be arranged between the bottom of the recess and the coupling element. Preferably, a rosette for mounting on a door leaf overlaps the handle and is so connected with the handle via a return spring, such that the handle is biased against a stop toward its closed-position. Thereby, the handle is in a well-defined, e.g. usually horizontal position also with an open clutch. 
         [0023]    Preferably, the handle has a door-side hollow shaft (a hollow shaft on a door-side of the handle), in which the output shaft and at least a part of the linear drive are disposed. Thereby, the handle protects the output shaft from unauthorized access and enables a particularly compact design. More preferably, the output shaft is rotatably mounted in the hollow shaft. When closing the switching clutch, the rotation is of course blocked or at least restricted. 
         [0024]    For example, the handle may have a handpiece that is non-rotatably connected with the hollow shaft with two legs being arranged angled (that is, at an angle with respect) to each other. The door handle then has the form of a conventional door lever. For mounting, it is advantageous if the handpiece comprises at least two half-shells, between which at least one fixing portion of the hollow shaft is arranged. For example, the half-shells may have a door-side external thread, on which a union nut is seated, which fixes the half-shells on the hollow shaft. The union nut should preferably be protected against unauthorized opening, e.g. be overlapped by a rosette or be locked by a stop only being reachable after dismounting the door handle. 
         [0025]    In the leg facing away from the door (i.e. in the leg of the handle being at least approximately parallel to the door leaf), a battery for energy supply of the door handle may be provided. For example, the ends of the half-shells facing away from the door may open into a hollow profile, which holds together their ends and e.g. provides space for at least one battery or for at least parts of a circuitry, such as a lock control. 
         [0026]    The linear drive preferably has at least one control member that is axially displaceable and rotatably mounted in the handle, which engages in the coupling element in such a way that a displacement of the control member results in a displacement of the coupling element. Accordingly, the control member has at least one “open-position” in which the clutch is open and one “closed-position” in which the clutch is closed. 
         [0027]    The control member preferably has at least one (e.g. slotted) thread, into which a pin or a complementary threaded portion engages, which is rigidly connected to the handle. Alternatively, the control member can also have only one thread-like contact surface for the pin or the threaded section, in which case the control member and/or the pin or threaded section, respectively, are mutually spring-loaded. Thereby, a rotational movement of the control member can be converted into a linear movement, i.e. a rotation of the control member also causes a linear movement, preferably axially to the rotation axis. 
         [0028]    The drive of the control member may e.g. be carried out by a motor controlled by a lock control. The motor may preferably be arranged in the handle and may drive a drive wheel for the control member, at least indirectly. The drive wheel may preferably be arranged coaxially to the rotation axis of the control member. The drive wheel is connected to the control member in order to entrain it with a rotational movement. Preferably, the control member and the drive wheel are connected via a spring element, e.g. a coil spring. The spring element compensates on the one hand the changes in distance between the adjusting element and the drive wheel during axial displacement of the adjusting element, and in addition serves as energy storage, when the adjusting element is blocked. If for example the control member is to be moved in the direction of the output shaft, it may occur that the coupling element, e.g. by actuating the handle, is stressed such that it jams. Accordingly, a movement of the control member in the direction of the coupling element is not possible. The motor can be controlled by the lock control, regardless of this circumstance. Thereby, it drives the drive wheel and loads the spring element in the corresponding direction of rotation. Once the coupling element is relieved, i.e. no longer jammed, the blockage of the control member is also relieved. The energy stored in the spring element is converted into a displacement of the control member, and thereby also the coupling element is displaced correspondingly. 
         [0029]    Preferably, the drive wheel is partially toothed, i.e. it has a toothed region and in the extension of the toothed region as well a non-toothed region, wherein the angular range being spanned by the toothed region corresponds to the rotation angle of the drive wheel, which rotation angle is necessary to adjust the control member between its “open-position” (in which the clutch is open) and its “closed-position” (in which the clutch is closed). 
         [0030]    In the handle, particularly in a cavity between at least two half-shells of the handle, electrical components, e.g. a lock control or a part thereof may be arranged. The lock control is adapted to exchange data with an electronic key, (e.g. an RFID transponder) via a data link (e.g. a radio data link). Based on the data, the lock control checks the locking authorization of the key and drives the linear drive, if the locking authorization does not correspond with the state of the clutch, i.e. for a given locking authorization the clutch is closed and is otherwise opened, if necessary. 
         [0031]    Herein the term ‘non-rotatably connected’ is used to express that two pieces are connected such that a transmission of torque from one piece to the other is (and vice versa) is possible. For example, when clutch having an input shaft and an output shaft is closed, the input shaft and the output shaft of the clutch are ‘non-rotatably connected’. In case the clutch is open, they are ‘ rotatably connected’. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    In the following, the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment and with reference to the drawings. 
           [0033]      FIG. 1 a    shows a perspective view of a door handle. 
           [0034]      FIG. 1 b    shows the door handle of  FIG. 1 a    in the front view. 
           [0035]      FIG. 2 a    shows a longitudinal section of the door handle along the plane A-A. 
           [0036]      FIG. 2 b    shows a detail of  FIG. 2   a.    
           [0037]      FIG. 3 a    shows a longitudinal section of the door handle along the plane B-B. 
           [0038]      FIG. 3 b    shows a detail of  FIG. 3   a.    
       
    
    
       [0039]    While the invention can be modified without changing its scope and take alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0040]      FIG. 1  shows a door handle  1 , here in the form of a door lever. The door handle  1  has a handle  10  being pivotable about a rotation axis  2 , with a door-side first leg  11 , the longitudinal axis  2  of which is oriented in approximately orthogonal direction with respect to a door leaf (when mounted on the door), and with a second leg  12  angled with respect to the first leg. The region in which the first and second legs meet at an angle consists of two half-shells  13 ,  14  being held together by a nut  15  on the door side and a sleeve  16  on the other side. As indicated, the handle  1  may have a receiving area for a square shaft  17 , to non-rotatably couple the door handle with the nut of a mortise lock. A rosette  18  may be provided to fasten and mounting the door handle  1  to a door leaf and protect the clutch (which will be described in more detail below) against manipulation. An output shaft  30  (cf.  FIGS. 2 a  to 3 b   ) is covered by the handle  10 , which output shaft  30  acts on the (illustrated as) square shaft  17 , i.e. it is connected with the square shaft  17  in a manner permitting transmission of a rotational movement. To be more precise, the rotational movements about the longitudinal axis  2  are transmitted. In contrast thereto, tilting moments applied orthogonally to the longitudinal axis  2  are preferably at least substantially absorbed from the bearing of the handle  10  by the rosette  18 , and are introduced into the door leaf. A clutch is located between the handle  10  and the output shaft  30 , in order to non-rotatably connect the handle  10  with the output shaft  17  by means of a lock control (clutch closed) or in order to uncouple both (clutch open). Preferably, the handle  10  rests on the rosette  18  via a return spring  19 , thus, the door handle does not hang down when the clutch is open. The rosette  18  may preferably be fastened to the door leaf from the inner side of the door, or may be fixed otherwise with same. 
         [0041]    The functioning of the door handle is explained by way of the two sections A-A and B-B, i.e. of  FIGS. 2 a  to 3 b   : The door handle  1  has an output shaft  30  on the door side, which is rotatably mounted in a hollow shaft  50  of the handle  10 . The output shaft  30  and the hollow shaft  50  have a common rotational axis  2  and may be non-rotatably coupled to each other via the clutch (or decoupled, if the clutch is open). The output shaft  30  is non-rotatably connected with the square shaft  17 , as illustrated. The hollow shaft  50  is non-rotatably connected with the handle  10 . In the example shown, the hollow shaft  50  has an attachment portion  52  by which it is fixed between the two half-shells  13 ,  14 . 
         [0042]    The output shaft  30  has a recess  31  on its side facing towards the hollow shaft  50 . In the recess  31  sits a coupling element  40 . The coupling element  40  is axially displaceable but not freely rotatable. The coupling element  40  is for example (circularly-)cylindrical and has a cam  401  on at least one side (two cams  401  are shown) which engages (engage) in a (each) complementary groove of the recess  31 . Alternatively, the coupling element  40  may have at least one flattened portion which interacts with a complementary flattened portion of the hollow shaft  50  and the output shaft  30 . It is only important that the coupling element  40  may (depend-ent on its position) generate a torque-transmitting form-fit connection with the hollow shaft  50  and/or with the output shaft  30 . The cylindrical part of the coupling element  40  is arranged coaxially with the rotation axis. 
         [0043]    The hollow shaft  50  has a receiving area  51  opposite to the recess  30 . The receiving area  51  is also complementary to the form of the coupling element  40 . If the coupling element  40  is displaced into the receiving area  51  in axial direction to an extend that the coupling element  30  engages both in the recess  31  and in the receiving area  51 , the hollow shaft  50  and thus the handle  10  are non-rotatably connected with the output shaft  30 , i.e. the clutch is closed. Therefore, the output shaft  30  is taken upon actuation of the handle, and the rotation movement is transmitted to the square shaft  17 . In other words, the rotation of the handle is transmitted via the clutch to the output shaft. 
         [0044]    When the coupling element  40  as shown is pushed back into the recess  31  of the output shaft  30  so far that it no longer engages with the receiving area  51  of the hollow shaft, the clutch is open. In the open state of the clutch, upon actuation of the door handle, the rotation is not transmitted to the output shaft  30 . 
         [0045]    The adjustment of the coupling element  40  is preferably carried out by means of a control member  41 . The example of shown control member  41  is rotatably mounted and axially displaceable the hollow shaft  50  on a rod  54 . The control member  41  has a thread-shaped slot  42  (more generally: a thread  42 ) into which a pin  53  engages radially as a complementary threaded section, said threaded section  53  is connected at least substantially rigid to the handle  10  via rod  54 . In the example shown, the rod  54  is held by a gear block  61 ; other fastenings are also possible. It is only important that the rod  54  and the control member  41  can be rotated relative to each other about the longitudinal axis  2 . Upon rotation of the control member  41  about its longitudinal axis  2 , said control member is either pushed forward in the direction towards the output shaft  30  according to the rotational direction, by interaction of the threaded section  53  and the thread  42 , or is pushed back in the opposite direction. If the control member  41  is pushed forward, it pushes the coupling element  40  against the force of a spring  32  (which spring rests against the bottom of the recess  31 ) so far into the recess  30 , that the coupling element  40  is not engaged with the receiving area  51 ; the clutch is now open. The control member has reached one of its two end positions, namely its “open end position”. If the control member  41  is rotated back and thereby retracted, the coupling element  40  follows the control member  41  into the receiving area  51  of the hollow shaft  50  due to the spring  32 , wherein the spring  32  is at least somewhat relaxed; the clutch is closed. The control member  41  now has reached the other end position, the so-called “closed end position”. 
         [0046]    To displace the control member  41  axially, it is rotatably driven about its longitudinal axis  2 . For this purpose, a motor  45  driven by a lock control (not shown) drives a drive wheel  44  via a preferably self-locking gear, the drive wheel  44  being arranged preferably coaxially with regard to the control member  41 . The drive wheel  44  thereby entrains a first end of a spring element  43  (at least indirectly). The other, second end of the spring element  43  is (at least indirectly) attached to the control member  41  such that upon rotation of the drive wheel  44  the control member  41  is rotated, provided that the coupling element is not blocked. Therewith, the adjusting element  41  and thus also the coupling element  40  are axially displaced due to the threaded section  53  engaging axially into the thread. If, however, the control member is axially blocked, the spring element  43  is loaded by the rotation of the both ends against each other. Once the blockage is relieved, the control member  41  follows the rotation of the drive wheel  44 , wherein the spring element is relaxed again. 
         [0047]    If the drive wheel  44  is driven to open the clutch, i.e. to push forward the control member  41 , it may occur that at the same time the handle  10  is actuated. In this case, the coupling element  40  is clamped between the output shaft  30  and the hollow shaft  50  and thereby blocks an axial displacement of the control member  41 . The coupling element is jammed. Therefore, only the spring element  43  is tensioned by the rotation of the drive wheel  44 , i.e. kinetic energy is stored as potential energy in the spring element  43 . If the handle  10  is released, the clamping of the coupling element  40  is relieved, i.e. the control member  41  being pre-loaded by the spring element  43  can push the coupling element  40  out of the receiving area  51  and thus into the “open-position”. 
         [0048]    Likewise, it may occur that the clutch is open when the door handle is actuated. In this case, the receiving area  51  of the hollow shaft  50 , i.e. of the handle is rotated against the recess  31  of the output shaft  30 , and the coupling element  40  cannot engage with the receiving area  51  even if the control member  41  is retracted. The coupling element  40  is not able to follow the control member  41 , despite the biasing of the bias spring  32 . Once the door handle is released, the grooves of the recess  31  and the receiving area  51  align, such that the coupling element  40  engages in the receiving area  51  of the hollow shaft  50 , thereby closing the clutch. 
         [0049]    Preferably, the drive wheel  44  is a partly toothed gear, i.e. the drive wheel has at least a first toothed region and a second non-toothed region, wherein the non-toothed region is disposed in the imaginary extension of the toothed region. For adjusting the first end of the spring element  43  being at least indirectly entrained by the drive wheel, an output element (e.g. a screw (see  FIG. 2 a   ), a gear rack, or other gear) being driven by motor  45  engages in the toothed region of the drive wheel  44 . The toothed region is arranged on the drive wheel in a manner that the toothing no longer engages in the output element, as soon as the first end of the spring element  43  has reached one of its two end positions. In the first end position, the control member is spring-loaded in the direction of its “closed end position” and in the other end position it is spring-loaded towards its “open end position”. To adjust the control member  41  between its respective end positions, it is sufficient to drive the motor for a sufficiently long time period with the corresponding rotation direction. Once the entrained end of the spring element  43  has reached its desired end position, the output element and the drive wheel  44  disengage. Thus, the motor  45  can be operated time-controlled, and sensors for detecting an end position of the first end of the spring element are not necessary. It is sufficient to determine the time constant for controlling the motor to be big enough. If the desired end position of the entrained first end of the spring element  43  has been reached and the drive wheel  44  and the driven element are not engaged with each other, the control member is now spring-loaded in the direction of its respective end position and the “last tooth” of the toothed region is correspondingly pushed against the complementary toothing of the output element by the spring element  43 . If the control member  41  is to be shifted into the other end position, it suffices to drive the motor  45  again for a sufficiently long time period, but with the reverse direction. Again, the teeth engage in one another until the entrained end of the spring element  43  has reached its second end position. Now, the control member is spring-loaded in the direction of its corresponding (different) end position, and due to the spring-load, the “first tooth” of the toothed region fits closely to the complementary toothing of the output element. Therefore, the drive wheel  44  would again be entrained by the output element with a repeated reversal of rotation direction of the motor  45 . 
         [0050]    The door handle has been described by way of an example, in which in mortise of an open clutch the coupling element is seated in the output shaft and the linear drive is integrated in the handle. This the output shaft to be kept relatively short, which makes an attack difficult. In principle, the clutch can be rotated by 180°. Then the coupling element  40  would sit in the handle in case of the open position. Independently of this, the linear drive may be arranged in the handle, or in or at the output shaft. An essential advantage of the invention is that the rosette does not accommodates any elements being necessary for switching of the clutch. Further it should be noted, that door handle can as well have the form of a door knob. In this case the second leg is omitted and the first leg is thickened to thereby provide a handle. 
         [0051]    It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide a door handle. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           2  rotation axis/longitudinal axis 
           10  handle 
           11  first leg 
           12  second leg 
           13  upper half-shell 
           14  lower half-shell 
           15  union nut 
           16  sleeve 
           17  square shaft 
           18  rosette 
           19  return spring 
           30  output shaft 
           31  recess of the output shaft 
           32  bias spring 
           40  coupling element 
           401  cam 
           41  control member 
           42  slot/thread 
           43  spring element, e.g. coil spring 
           44  drive wheel 
           45  motor 
           50  hollow shaft 
           51  receiving area 
           52  attachment portion 
           53  pin/threaded section 
           54  rod 
           61  block gear