Abstract:
A seat adjusting device for an automobile seat ( 1 ) having an electric motor ( 11 ) for generating a drive motion, wherein the electric motor is operationally coupled to a gearbox ( 13 ) for transmitting the drive motion thereof, the gearbox having a gearbox housing ( 19 ) in which gearbox elements are disposed for a step-up or step-down transmission of the motor drive motion, by means of which electric motors of lesser technical complexity can be used than previously. To this end, the invention proposes that the gearbox ( 13 ) has detection device for detecting information about the speed of at least one of the gearbox elements or detecting a variable dependent on the speed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a United States National Phase application of International Application PCT/EP2009/004900 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2008 032 162.1 filed Jul. 8, 2008, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a seat adjusting device for an automobile seat, having an electric motor for generating a drive motion, wherein the electric motor is operationally coupled to a gearbox for transmitting the drive motion thereof, said gearbox having a gearbox housing in which gearbox elements are disposed for a step-up or step-down transmission of the motor drive motion. Such a generic seat adjusting device is known from DE 10 2004 019 466 B4, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0003]    Automobile seats, in particular single seats, are generally constructed so as to be adjustable. Here, on the one hand, the seat as a whole can be longitudinally adjustable, for which a seat part of the automobile seat is fastened to an upper track and the upper track is longitudinally displaceable with respect to a lower track fastened on the automobile side. 
         [0004]    In addition, usually a backrest part of the automobile seat is swivelably articulated on its seat pan part. The articulation is produced here by fittings which have components on the seat pan part side and also on the backrest part side, which are swivelable or rotatable relative to each other. Several different types of fitting exist for this; detent fittings or tumble fittings are frequently used. 
         [0005]    Either a manual or a motor-driven adjustment movement can be provided to carry out the movements of the automobile seat. To produce motor drive motions, generally electric motors are used, in particular electric direct current motors, owing to the direct current network in motor vehicles. As such direct current motors usually provide drive motions with high rotation speeds, which are not able to be used directly as an adjustment movement, a reduction takes place by means of the gearbox. With the reduced movement, the seat or respectively a seat component is adjusted. 
         [0006]    In particular for memorized seat functions, such as for example in the case of a stored longitudinal position of the seat with respect to the lower track of the seat or a particular backrest inclination, the electric motors have detection means in order to be able to establish the number of revolutions and/or rotation speed of the motor. This information is used by a control of the seat adjusting device, in order to transfer the seat or its components into the desired stored position. In particular with a plurality of different seats, this can lead to a large number of different electric motors, which involves high costs. In the previously known solutions, in addition it is a disadvantage that owing to the high rotation speeds of the electric motors used hitherto, high scanning frequencies are necessary, which in turn lead to a large amount of data which are to be processed, which in turn make high-performance and expensive evaluation electronics necessary. Furthermore, through the high frequencies, high electromagnetic loads occur, which in turn entail a high expenditure to achieve an immunity to interference in the respectively adjacent assemblies. 
         [0007]    Such a seat adjusting device, in which the motor rotation speed is detected and the position of the automobile seat is calculated therefrom, is disclosed in DE 3527906 A1. 
       SUMMARY OF THE INVENTION 
       [0008]    According to a first aspect, the invention is therefore based on the problem of providing a seat adjusting device of the type named in the introduction, which requires electric motors of lesser technical complexity than previously. According to a second aspect of the invention, a seat adjusting device is to be made possible which makes less high-performance evaluation electronics necessary than previous seat adjusting devices for the production of predetermined adjustment paths. 
         [0009]    This problem is solved according to the invention in a seat adjusting device of the type named in the introduction in that the gearbox has at least one detection means, such as for example a sensor, to determine the rotation speed of a gearbox member or of a variable dependent on the rotation speed. In addition, evaluation electronics are to be arranged on the gearbox for evaluation for signals provided by the at least one detection means. 
         [0010]    Unlike in the previous solutions, in which the detection means are arranged in the motor and require a high scanning frequency owing to the high rotation speeds of the motor shaft, in the solution according to the invention the lower rotation speeds, owing to the reduction taking place in the gearbox, can be used. The rotation speeds, which are usually distinctly lower, lead to lower scanning frequencies, which in turn make a less high-performance evaluation electronics necessary. If, on the other hand, similarly high-performance evaluation electronics are used as hitherto, then calculating capacities for other applications are now available in the evaluation electronics. Furthermore, the disturbance behavior at low frequencies is considerably less, which in turn has a positive effect on the surrounding peripheral electronics. 
         [0011]    In addition, the solution according to the invention makes technically less complex motors possible, which are suitable both for automobile seats without memory function and also for seats with memory function. As the detection means, in contrast to previously known solutions, are now advantageously arranged on or in the gearbox instead of on the motor, motors for seat adjusting devices with a memory function can now also be used which have no detection means for determining the rotation speed. As these motors can also be used for seats without memory function, this can be used for a standardization of the electric motors with otherwise different seat adjusting devices. The motor or respectively the drive unit can therefore be provided as a standard component, which can lead to higher numbers of units and hence to lower costs of the individual electric motors. The measure provided according to the invention of providing the evaluation electronics for the evaluation of the signals provided by the at least one detection means in whole or in part on the gearbox and not on the motor also contributes to this. Hereby, the motor is also relieved of functions and can be standardized. It is particularly advantageous here if the at least one detection means is integrated into the evaluation electronics, in particular is arranged on a shared board with the evaluation electronics. 
         [0012]    The problem is also solved according to the invention in a seat adjusting device of the type named in the introduction in that an electrical connection for the current supply and/or for data exchange is provided on the gearbox and that in addition the gearbox is provided with means for conveying current from the gearbox to the motor for the current supply of the latter, in particular for its production of a motor drive motion. These measures can be provided alone or in combination with the first aspect of the invention. Also with such a solution it is possible with less technical effort than hitherto to provide a smaller number of different motor types for different seat adjusting devices. Therefore, this aspect according to the invention can also be used to provide both seats with memory function and also seats without memory function with the same motor type. In addition, through the solution according to the invention, in which at least one electrical contact is present on the gearbox, it is simpler than hitherto to form a modular system for various motor- and gearbox embodiments, because an interface can be defined for the current supply and/or for the data exchange between the electric motor and the gearbox. It is preferred here if the electrical contacting of the motor takes place via the gearbox. For this, the gearbox and the motor can be respectively provided with a contact means, which can be connected with each other. The contact means can be connected directly with each other here, and can be constructed for this in the manner of a plug/socket. In other embodiments, the electrical contact means of the gearbox and of the motor can also be connected with each other by line means. 
         [0013]    It has proved to be advantageous if the gearbox is also provided with a control unit which is arranged on the gearbox itself. The control unit can advantageously undertake all the control functions which are necessary for carrying out movements of the respective seat. Provision can also be made that the control unit only controls the functions which are necessary for operating the respective drive of the seat adjusting device. It has proved to be advantageous here if the control unit has a board with electronic circuits, with the board being arranged on the gearbox, preferably on the gearbox housing and particularly preferably inside the housing, whereby the control unit is protected from damage and contamination. The control unit can contain both the necessary control electronics and also power electronics for the motor. 
         [0014]    In a preferred embodiment of the invention, at least one sensor, constructed as detection means, can be provided on the gearbox, by which information is determined with regard to the rotary movement of a rotatably arranged gearbox member. Such a sensor can advantageously be a sensor using inductive or magnetic effects, such as for example a Hall sensor. The magnets necessary in connection with Hall sensors can be arranged in various ways on the rotating gearbox member, for example can be glued on. However, it is particularly preferred if favorably priced synthetic sintered material is magnetized at predetermined sites of the gearbox member which is provided for this. In this way, the complex measure of the integration of additional magnets is dispensed with. The production methods necessary for this are previously known per se and are offered and carried out for example by the company MS-Schramberg GmbH &amp; Co. KG, D-78713 Schramberg-Sulgen. 
         [0015]    The at least one sensor provided for detecting the rotation speed information, preferably a Hall sensor, can be integrated into the control unit, in particular can be arranged on a board of the control unit. The control unit can be advantageously arranged on the gearbox, in particular inside its gearbox housing, such that the at least one magnet runs past the Hall sensor on the rotation of the gearbox member, and this is able to be detected by the Hall sensor. 
         [0016]    In principle, any type of gearbox having at least one rotating gearbox element can be used in connection with the seat adjusting device according to the invention. The invention can have for example at least one wobble, planetary, worm or spur gearbox and combinations of these gearbox types. Particular advantages can be achieved with gearboxes which have a high reduction gear ratio because in these gearboxes—compared with the respective rotation speed of the drive motor—particularly low rotation speeds occur. In connection with the present invention, it is therefore expedient if with the detection means the rotation speed or respectively rotation movement is detected of the gearbox element which has the lowest rotation speed in the gearbox. In many cases, this will be the gearbox element on the output side, by which the rotary movement is delivered from the gearbox to the seat element which is to be adjusted. 
         [0017]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    In the drawings: 
           [0019]      FIG. 1  is a perspective view of an automobile seat with a seat adjusting device according to the invention; and 
           [0020]      FIG. 2  is a highly diagrammatic view of a basic representation of a seat adjusting device according to the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    An automobile seat  1  of a motor vehicle has a seat pan part  3  and a backrest  4 , which is arranged by means of two fittings laterally on the seat pan part  3 , is swivelable relative thereto and is able to be locked with different inclination settings. The alignment of the automobile seat  1  in the motor vehicle and its usual travel direction on the one hand and the symmetry and arrangement of the fittings in the automobile seat  1  on the other hand define the direction indications which are used. The automobile seat is constructed as a seat with integrated seatbelt, i.e. the upper end of a safety belt is fastened to the backrest  4 , more precisely to an automatic belt retraction device on the upper edge of the backrest. 
         [0022]    For the longitudinal displacement of the seat, the latter is arranged with its seat pan part  3  on two seat track pairs  5 ,  6  aligned parallel to each other at a distance. Each seat track pair  5 ,  6  has a lower track  5   a ,  6   a  fastened on the automobile floor, and an upper track  5   b ,  6   b  guided on the seat lower track  5   a ,  6   a  and longitudinally displaceable relative thereto. Each seat upper track  5   b ,  6   b  is operationally coupled to an electric seat adjusting device  10  according to the invention. Here, in an embodiment a shared seat adjusting device  10  can be provided for both seat track pairs. In alternative embodiments to this, each seat track pair  5 ,  6  can have its own seat adjusting device associated with it. In the latter case, a coupling of the movements of the two seat upper tracks can be provided, in particular a mechanical coupling or an electronic coupling of the two motors of the seat adjusting devices, as is described for example in DE 198 60 910 B4, the entire contents of which are incorporated herein by reference. 
         [0023]    The seat adjusting device according to the invention has a direct current electric motor  11 , shown in  FIG. 2 , the drive shaft  12  of which is operationally coupled to a reduction gearbox  13 . The reduction gearbox  13  of the example embodiment is connected with at least one of the upper tracks  5   b ,  6   b  and has a worm  14  on the input side, which meshes with a worm wheel  15 . The worm wheel  15  in turn meshes with a spur cogwheel  16 , which is arranged on a drive shaft on the gearbox side. In addition, a further cogwheel which is not illustrated in the figures is arranged on the output shaft, which cogwheel is in engagement with a rack of the lower track. The rotary movement of the drive motor  11  therefore leads to a reduction of the drive motion, preferably in a ratio of a range of 150:1 to 250:1, which in turn leads to a translatory movement of the upper tracks  5   b ,  6   b  and hence of the seat in the longitudinal direction of the automobile. 
         [0024]    As can be seen in particular from  FIG. 2 , the gearbox  13  has a housing  19 , on the outer side of which a first electrical contact plug  20  is provided, which can be constructed as a bus contact plug. Via the bus cable  21 , which is able to be connected to the bus contact plug  20 , the gearbox housing  19  can be connected with an electrical energy source, in particular a car battery, and with an actuating element, for example a switch. In different embodiments than the one illustrated, the gearbox can also be connected with an external control of the seat adjusting device by means of the bus contact plug  20 . 
         [0025]    By means of the actuating element, which is not illustrated and is situated outside the gearbox in a favorable operating position, an adjustment movement which is to be carried out to the seat adjusting device, i.e. a kind of run command for the electric motor, can be triggered by the user of the seat, corresponding to particular numbers of revolutions of each of the gearbox elements. The bus contact plug  20  is connected in turn with an electronic circuit arranged in the gearbox housing  19 , which has the function of a control for the seat adjusting device. The electronic circuit can be arranged on a board  23  which is fastened on the inner side of the gearbox housing. The board  23  is situated here directly opposite the spur cogwheel  16 , the gearbox element which moves with the lowest rotation speed in the gearbox. 
         [0026]    The gearbox housing  19  has a second contact plug  24 , by which the motor  11  is able to be connected electrically with the gearbox housing  19 . For this, the electric motor  11  with its housing  19  is preferably connected directly on the contact plug  24  of the gearbox housing using suitable contact means. Alternatively, this can also take place with the use of a cable. The second contact plug  24  is either connected directly with the first contact plug or electrically via the board  23 , whereby a connection of the electric motor  11  to the on-board network of the automobile takes place for the current supply. The electric motor  11  therefore obtains the energy necessary for its drive via the gearbox. 
         [0027]    A Hall sensor  25 , constructed as a Hall IC, is arranged on the board as detection means, which is situated hereby in the immediate vicinity of the spur cogwheel  16  arranged on the output side in the gearbox. The spur cogwheel  16  is manufactured from a sintered material, for example a synthetic sintered material, which makes it possible that locally limitedly magnetic material can also be integrated into the material of the spur cogwheel in this example embodiment. In this way, one or more magnets  26  can be integrated into the spur wheel, wherein in the case of several magnets  26 , these are preferably to be distributed uniformly on the periphery. In this way, the rotary movement of the spur cogwheel  16  can be scaled further. Depending on the number of magnets which are introduced per revolution, a pulse frequency can be adapted with respect to the increments per revolution of the respective reduction stage. An increase to the release can also be achieved by several sensors which are preferably arranged distributed uniformly on the periphery of the spur cogwheel  16 . 
         [0028]    In this example embodiment, impulses are therefore generated by means of the Hall sensor  25  and the at least one magnet  26  on the spur cogwheel  16  as a function of the rotation speed of the spur cogwheel  16 , which is supplied to the electronic circuit integrated into the gearbox and arranged on the board  23 . There, the rotation speed measurement, based on the Hall sensor, is evaluated. As a function of the measured Hall sensor increments, the respectively desired reaction can take place from the electronic circuit, in order to thereby control the motor. With this control, the rotation speed of the electric motor can be controlled in particular by means of the measured number of revolutions of the spur wheel  16 . Here, a rotation speed regulation of the motor based on pulse width modulation (PWM) is preferred. Likewise, with the determined rotation speed or number of revolutions of the spur wheel  16 , a traveling distance of the seat of predetermined length can also be controlled and hence produced. The length of the traveling distance is produced here by means of a calibration of the predetermined number of revolutions of the spur wheel with the measured actual number of revolutions of the spur wheel  16 . As soon as this predetermined number of revolutions has been covered, the motor is stopped by the control. 
         [0029]    In other embodiments, the number of revolutions of the spur wheel or of another gearbox member can be used as the applicably determinative variable for covering a predetermined rotation angle by a rotatably or swivelably adjustable component of an automobile seat. The structure and the mode of operation of such a seat adjusting device can basically correspond to the structure shown in  FIG. 2 . In contrast to the example embodiment previously discussed, in the case of a backrest adjustment the rotary movement of the spur wheel is not converted into a translatory movement, but rather is used as a rotary movement. 
         [0030]    While specific embodiments of the invention have been described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
       LIST OF REFERENCE NUMBERS 
       [0031]      1  automobile seat 
         [0032]      3  seat pan part 
         [0033]      4  backrest 
         [0034]      5  seat track pair 
         [0035]      5   a  seat lower track 
         [0036]      5   b  seat upper track 
         [0037]      6  seat track pair 
         [0038]      6   a  seat lower track 
         [0039]      6   b  seat upper track 
         [0040]      10  seat adjusting device 
         [0041]      11  electric motor 
         [0042]      12  drive shaft 
         [0043]      13  gearbox 
         [0044]      14  worm 
         [0045]      15  worm wheel 
         [0046]      16  spur cogwheel 
         [0047]      19  gearbox housing 
         [0048]      20  contact plug 
         [0049]      21  bus cable 
         [0050]      23  board 
         [0051]      24  contact plug 
         [0052]      25  Hall sensor 
         [0053]      26  magnet