Abstract:
A transmission emergency release for an automatic transmission which is mechanically blocked when a parking mode is engaged, includes a manually operable actuating element for the mechanical deactivation of the parking mode, wherein the actuating element has a vehicle-fixed mount ( 1, 29 ) with a force transmitting element and an actuating lever ( 9, 25 ) which is insertable in the vehicle-fixed mount ( 1, 29 ) to disable the parking mode in order to disable the parking mode by means of the force-transmitting element.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2012/004870, filed Nov. 24, 2012, which designated the United States and has been published as International Publication No. WO 2013/079182 A1 and which claims the priority of German Patent Application, Serial No. 10 2011 119 747.1, filed Nov. 30, 2011, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The invention relates to a transmission emergency release for an automatic transmission which is mechanically blocked when a parking mode is engaged, and includes a manually operable actuating element for mechanical disabling the parking mode. 
     Automatic transmissions for motor vehicles having an operating range which is divided into various manually selectable operating modes, which are referred to as drive positions. The drive positions include also the parking mode (parking position) and the neutral position. Drive positions of an automatic transmission are selected by the driver on a control unit, resulting in electro-hydraulic actuators to be engaged in the automatic transmission. When the parking mode is engaged, the automatic transmission is mechanically blocked so that the vehicle cannot be towed in the event of a power failure or a fault in the associated electronic control. In order to release this lock, a mechanical emergency release has to be actuated. The same problem exists also in newer automatic transmissions in which control inputs by the driver are transmitted via a shift-by-wire control element electronically to the automatic transmission. 
     DE 10 2007 011 614 A1 describes a transmission emergency release which is coupled to the gear selector. This apparatus is also suitable for shift-by-wire systems. The transmission emergency release can be activated by a coupling member which can be formed for example as a lever. 
     DE 199 40 029 A1 discloses a drive position selecting device with an emergency operation for a parking lock, which includes a Bowden cable that is connected to a lever. To trigger the emergency operation, a tensile force is applied upon the Bowden cable so that the lever is pivoted and the automatic transmission is released. 
     DE 101 40 164 A1 discloses a transmission emergency release in which unlocking is implemented by the transmission selector lever. A release mechanism is secured by a lock, the release mechanism is liberated after unlocking the lock so that the transmission selector can be pivoted beyond a movement limitation, resulting in a release of the parking mode mechanically via a Bowden cable. 
     Implementing a transmission emergency release requires solution of a number of problems: The cable pull has to be operated by a force that cannot be manually applied, therefore a force multiplication has to be integrated into the emergency release. In order to prevent uncontrolled rolling of the vehicle when operating the emergency release, the foot brake has to be applied at the same time. Thus, the emergency release has to be positioned within reach of the driver. To limit the length of the cable pull, the emergency release must be positioned in the vicinity of the transmission. As a result, only a few locations exist in the vehicle to accommodate the transmission emergency release. When the transmission is located in the front, the emergency release is suitably accommodated in the driver-side footwell. When the transmission is located in the rear, the emergency release is suitably accommodated in the center console or next to the driver seat or in the rear-window shelf when a two-seater is involved. 
     Conventional transmission emergency releases require large installation space and can be easily installed only in larger vehicles. When small cars or sports cars are involved, this is not possible due to the requirements of body shell, chassis and ergonomics. 
     SUMMARY OF THE INVENTION 
     The invention is therefore based on the object to provide a transmission emergency release having reduced need for installation space. 
     This object is achieved according to the invention by a transmission emergency release of the aforementioned type by providing the actuating element with a vehicle-fixed mount with a force-transmitting element and an actuating lever which is insertable in the vehicle-fixed mount to deactivate the parking mode in order to disable the parking mode by means of the force-transmitting element. 
     The invention is based on the recognition that a major part of the required installation space can be saved in critical areas by configuring the actuating element in two parts with a vehicle-fixed mount and an actuating lever which is separate from the mount and is inserted in the vehicle-fixed mount only in case of need, i.e. when executing an emergency release of the transmission. During normal operation, the actuating lever can be stowed at a different location in the vehicle. The space-intensive mechanism in the form of the actuating lever projects into the passenger compartment only for a limited time period during an emergency release of the transmission and is otherwise part of the on-board tool kit. Thus, additional storage space in the center console is provided, for example. 
     It is expected that automatic transmissions with shift-by-wire operation increasingly come into use in the future, particularly in the context of the increasing use of hybrid vehicles. It can also be assumed that the number of control devices continues to increase in the future so that problems to find installation space may arise. The transmission emergency release according to the invention can therefore be used advantageously also in small cars or sports cars, as it requires only very little installation space. 
     In the transmission emergency release according to the invention, it is particularly preferred that the actuating lever can be coupled with the vehicle-fixed mount in a formfitting manner. In the coupled state, the force needed for the release can be applied and transmitted to the force transmitting element. 
     A particularly space-saving attachment is realized, when the vehicle-fixed mount of the transmission emergency release according to the invention has a plate in which a matingly shaped portion of the actuating lever can be inserted. This plate requires only little space so that the interior of the vehicle is not adversely affected unnecessarily. 
     According to a refinement of the transmission emergency release according to the invention, the actuating lever can be provided with a locking element which is insertable into a vehicle-fixed opening. This opening may be formed in particular as a groove or hole. The locking member provides a firm linkage of the actuating element with the vehicle-fixed mount so that the parking mode can be disabled in this state. 
     A particularly reliable operation is obtained when the transmission emergency release according to the invention has a tie rod which is arranged in the mount and connected to a cable pull and which can be coupled in the mount with the actuating lever by a form fit and/or interference fit, when inserting the actuating lever. The coupling is preferably established automatically when inserting the actuating lever. 
     According to a refinement of the invention, the actuating lever can include a hand crank, and preferably a force multiplication to reduce the actuating force that has to be applied manually. In this way, an emergency release can be executed with little effort by a user. 
     As an alternative, the actuating lever of the transmission emergency release according to the invention can have a carriage which can be coupled with the vehicle-fixed mount by a form fit and can be coupled with a lever handle to disable the parking mode by a tie rod which is arranged in the mount and connected to a cable pull. 
     It is also within the scope of the invention that the actuating lever has an external thread and/or a pin so that the actuating lever is guided by an internal thread and/or a guideway of the housing. Preferably, the thread is configured such that no self-locking occurs. The carriage coupled to the actuating lever is non-rotatably supported on the housing and axially movable. It is rotatably mounted to the actuating lever and is moved along as the actuating handle is axially moved. When being rotated, the actuating lever moves via the thread and/or guideway axially upwards and pulls the carriage with the tie rod with it so that the parking mode is disabled via the force transmitting element. According to a refinement of the invention, the actuating lever can be locked in an end position when the actuating element is actuated (activated). The guideway of the housing is formed such that the pin of the actuating lever is locked in the end position. Thus, the user receives a feedback so as to be able to recognize when the parking mode is disabled and the transmission is released. 
     According to a refinement, the transmission emergency release can be transferred back to its original position when the user applies a force with the assistance of a return spring. 
     Preferably, the locking mechanism of the transmission emergency release is provided with a peg or ejector which presses the pin from the end position, when the locking mechanism is pushed up. As a result, the locked position is released again, the carriage is moved downwards and the deactivation of the parking mode is reversed again, when the actuating element is removed. 
     Besides the described manually operable variants of the transmission emergency release according to the invention, the provision of an electrified variant is possible. The latter includes an integrated electric motor which is supplied with energy by an accumulator. Instead of an actuating lever, a push button is provided on the actuating element to replace an actuating handle or an actuating lever. The lower region of the actuating element, which includes a housing, a guide sleeve and an outer thread and/or a pin, remains the same however. This electric variant is inserted and locked in the vehicle-fixed mount like the manually operable variant. Actuation of the push button causes the electric motor to move a structure by which the carriage is pulled up so that the parking mode is disabled, The accumulator supplies the energy necessary for the actuation, when the on-board electrical system has failed. A powerful accumulator such as a lithium-ion battery that provides functional life for many years is especially appropriate. 
     Primarily, the transmission emergency release is provided for such cases, when the entire on-board electrical system has failed. In the event, a malfunction causes only part of the on-board electrical system to fail or the automatic transmission is locked for another reason, the provision of a connection of the transmission emergency release according to the invention to the on-board electrical system is conceivable as power source in addition to the integrated accumulator. For this purpose, the transmission emergency release has a respective electrical connection, for example a contact point. The actuating element has a corresponding mating contact point and a wiring for the power supply to the electric motor. In these cases, the integrated accumulator provides only an “emergency solution”. 
     For larger vehicles, for example trucks, the passenger compartment and the automatic transmission are located far apart, the cable pull is therefore very long and cumbersome accordingly. To avoid this disadvantage, an electrical decoupling can be provided between the transmission emergency release and the automatic transmission. The mechanism for the electric emergency release may be located outside the driver&#39;s cab in the vicinity of the automatic transmission. Inside the cab, there is a remote control which is connected to the on-board electrical system and/or an independent power source (accumulator). For actuating the transmission emergency release according to the invention, the driver is able to operate the remote control from the passenger compartment. The remote control sends a signal to the emergency release so that the integrated electric motor pulls the force transmitting element, in particular a cable pull, to thereby disable the parking mode. 
     In addition to the remote control, the emergency release requires a transmitter and a receiver for receiving the signal from the remote control and to send back a corresponding signal after the release of the automatic transmission. In this way, the driver obtains feedback via an indicator light after the parking mode of the automatic transmission has been disabled. 
     In addition, the invention relates to a motor vehicle. The vehicle according to the invention has a transmission emergency release of the described type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Further advantages and details of the invention are explained based on exemplary embodiments with reference to the drawings. The drawings are schematic illustrations and show: 
         FIG. 1  a perspective view of a vehicle-fixed mount of a first exemplary embodiment of a transmission emergency release according to the invention; 
         FIG. 2  the vehicle-fixed mount shown in  FIG. 1  and an actuating lever having a hand crank; 
         FIG. 3  the actuating lever after insertion into the mount; 
         FIG. 4  a detail of the actuating lever, showing its base being inserted into the mount; 
         FIG. 5  a second exemplary embodiment of a transmission emergency release according to the invention with an actuating element having a carriage; 
         FIG. 6  a sectional view of the actuating element shown in  FIG. 5 ; 
         FIG. 7  an actuating lever with greater leverage; 
         FIG. 8  a tie rod; 
         FIG. 9  a further exemplary embodiment of a tie rod; 
         FIG. 10  a further exemplary embodiment of a vehicle-fixed mount; 
         FIG. 11  a further exemplary embodiment of a transmission emergency release according to the invention; 
         FIG. 12  an enlarged view of the guideway; 
         FIG. 13  the transmission emergency release in the end position; 
         FIG. 14  the locking in the end position of  FIG. 13  by way of an enlarged view; and 
         FIG. 15  the transmission emergency release during unlocking by a pin. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of a vehicle-fixed mount  1  as component of an actuating element of a transmission emergency release for an automatic transmission of a motor vehicle. The vehicle-fixed mount includes a plate  2  which is angled in relation to a fastening portion  3 . The fastening portion  3  is securely connected to a vehicle body  4 , in the illustrated embodiment, it is welded. A clearance is formed between the vehicle body  4  and the fastening portion  3  for insertion of an actuating element. The vehicle-fixed mount  1  is symmetrical in configuration and has in midsection a one-sided opening  5  into which an actuating element can be inserted. The one-sided opening  5  is configured as a rectangular recess of the plate  2 . 
     In  FIG. 1  a tie rod  6  of T-shaped configuration is located in the opening  5  and connected at its lower end to a cable pull  7 . The cable pull  7  is part of a Bowden cable whose other end is attached to an automatic transmission so that the parking mode of the automatic transmission can be disabled by a pulling force acting on the tie rod  6 . 
     Provided next to the opening  5  of the plate  2  is a vehicle-fixed opening which is configured as a groove  8 . An actuating element formed as an actuating lever can be inserted and locked in the groove  8 . 
       FIG. 2  shows the vehicle-fixed mount  1  and an actuating lever  9 . The actuating lever  9  includes a crank  10  to exert a pulling force upon the tie rod  6  in the coupled state. The actuating lever  9  has front and rear base portions  12 ,  13  of a shape and size suited to the plate  2 . The base portions  12 ,  13  can be pushed laterally into the clearance between the plate  2  and the vehicle body  4  until the actuating lever  9  is located in the opening  5 . Thereafter, a latch  11  can be pressed into the groove  8  to formfittingly couple the actuating lever  9  to the vehicle-fixed mount  1 . During insertion or engagement, the tie rod  6  is received at the same time in form-fitting manner in a carriage inside the actuating lever  9 . 
     The crank  10  is connected via a multiplier  14  with a cable pull  15  having a carriage  16  at its lower end. During engagement, the tie rod  6  is formfittingly received in the carriage  16 , as shown in  FIG. 4 . 
     As the crank  10  is turned, the cable pull  15  is pulled up together with the attached carriage  16  via the multiplier  14  so as to apply a pulling force on the tie rod  6  and the cable pull  7  connected therewith. In order to prevent the carriage  16  from recoiling, when the crank  10  is released, the actuating lever  9  has a wedge brake  17 . In order for the carriage  16  to assume the initial position shown in  FIG. 3  prior to carrying out a transmission emergency release, a return spring  18  is mounted above the carriage  16  for pushing the carriage  16  downwards. Turning the crank  10  overcomes the force of the spring  18  and the carriage  16  is pulled upwards. 
     In other exemplary embodiments, the crank  10  has a locking bolt to lock the crank  10  in the end position, after deactivation of the parking mode. 
       FIGS. 5 and 6  show a second exemplary embodiment of the essential components of a transmission emergency release. The vehicle-fixed mount  1  secured to the vehicle body  4  essentially corresponds to the one of the first exemplary embodiment. 
     The actuating element includes a tubular housing  19  which can be engaged in the plate  2 . A latch  20  is located on a side of the housing  19  and can be pressed downwards after engagement into the groove  8  in order to formfittingly connect the actuating element to the vehicle-fixed mount  1 . 
     Inside the housing  19  is a carriage  21  which is non-rotatably received in the housing  19 . Extensions or projections  22  are provided on the outer side of the carriage  21  to prevent rotation of the carriage  21  relative to the housing  19 . An upper portion of the carriage  21  has an outer thread  23 . The tie rod  6  is received in the lower portion of the carriage  21  and has an underside where the cable pull  7  is located. 
     The actuating element further includes a hollow handle  24  with an internal thread which is threadably engaged onto the external thread  23  of the carriage  21 . 
     When rotating the handle  24 , the connection of the internal thread in the handle  24  with the external thread  23  of the carriage  21  causes an upward movement of the non-rotatably mounted carriage  21  with the tie rod  6  form-fittingly received therein. 
     Due to the force transmission via the self-locking threads, the necessary forces can be translated on one hand, and, on the other hand, an undesirable recoiling of the carriage  21  is precluded in the direction of the body  4 . The exemplary embodiment shown in  FIGS. 5 and 6  is characterized by a small number of components. 
     The actuating element, comprised essentially of the housing  19  and the handle  24 , is inserted in the vehicle-fixed mount  1  only for execution of a transmission emergency release, otherwise, it is stowed at a different location in the vehicle, for example in the on-board tool kit. 
       FIG. 7  shows an embodiment of a differently structured actuating lever. Basically the actuating lever  25  shown in  FIG. 7  corresponds to the actuating lever  9  of the first exemplary embodiment. The actuating lever  25  includes, however, a handle  26  having a longer lever arm so that in addition to the multiplication, the operating forces are reduced. 
       FIGS. 8 and 9  illustrate alternative embodiments of a tie rod.  FIG. 8  shows a tie rod  27  having a ball head which can be received by a correspondingly shaped carriage. As a further alternative,  FIG. 9  shows a pear-shaped tie rod  28 , which can also be received and pulled by a correspondingly shaped carriage. In the tie rods shown in  FIGS. 8 and 9 , a form-fit connection is present but also other embodiments are conceivable in which the tie rod is received in the carriage by interference fit. 
       FIG. 10  finally shows an alternative exemplary embodiment of a vehicle-fixed mount  29 . The vehicle-fixed mount  29  is attached in the area of a tunnel  30  of a vehicle body and integrated into an anyway existing body component  31 . In the region of attachment of the body component  31  to the tunnel  30 , the vehicle-fixed mount  29  has—analogous to the mount  1  shown in  FIG. 1 —an opening  32  and an angled plate  33 , thereby forming a clearance in which an actuating element is engageable. By integrating the vehicle-fixed mount into an existing body component  31 , the transmission emergency release can be realized especially easily and with little effort. 
       FIG. 11  shows an exemplary embodiment of a transmission emergency release, with an actuating lever  34  having an external thread  35  which interacts with an internal thread of a housing  36 . The external thread  35  and the internal thread  37  are configured such that no self-locking occurs. 
     The housing  36  includes a guideway  38 , which extends helically and into which a pin  39  of the actuating lever  34  is guided. A carriage  40  is rotatably mounted on the actuating lever  34 , the carriage  40  is restrained against rotation relative to the housing  36  and axially displaceable. When being rotated by a user, the actuating lever  34  is moved by means of the meshing threads  35 ,  37  and the pin running in the guideway  38  axially away from the vehicle body  4  (upwards). A tie rod, which is mounted on the lower end of the carriage  40 , is pulled upwards to thereby disable the parking mode. 
     Arranged between the housing  36  and the carriage  40  is a spring element  41  which generates a recoiling force when the actuating lever  34  is released to thereby move the actuating lever  34  back into the starting position. 
       FIG. 12  shows the area of the guideway  38  of the housing  36  on an enlarged scale. In  FIG. 12 , the pin  39  is in its initial position, i.e. in the non-actuated state in which the parking mode is activated. Upon unlocking by a user, the pin  39  is moved by the rotation of the actuating lever  34  along the guideway  38 , as indicated by the double arrow. 
       FIG. 13  shows, together with  FIG. 14 , the end position after the pin  39  has reached the upper end of the guideway  38 . At the upper end of the guideway  38 , the latter has a projecting detent portion  42  behind which the pin  39  locks into place. This engagement is perceived by the user who can then recognize that the actuating lever  34  is in the locked position. 
     When applying a force, the user is able to guide the pin  39  over the detent portion  42 , the pin  39  is guided along the guideway  38  under the action of the spring element  41 , while the carriage  40  is lowered until reaching again the initial position. The actuating lever  34  rotates hereby also back to the initial position. Unlocking by lifting the pin  39  over the detent portion  42  is shown in  FIG. 15 . When being pushed upwards, the locking element  43  automatically presses by means of an ejector  44  the pin  39  from the locked end position over the detent portion  42 . This ensures that the emergency release is disabled, when the actuating element is removed from the vehicle-fixed mount, and the carriage assumes in its starting position at the bottom.