Abstract:
A control element is provided for a motor vehicle, particularly a rotary actuator, having at least one pivoted control knob, an extension formed on the control knob, and an electrical device to detect the rotary movement of the control knob, whereby the electrical device works together with the extension of the control knob, and whereby the electrical device is formed of at feast two oppositely polarized magnets connected torsion-proof to the extension and by at least two sensors held stationary in the control element and detecting the magnetic field lines of the magnets.

Description:
This nonprovisional application is a continuation of International Application No. PCT/EP2006/007220, which was filed on Jul. 21, 2006, and which claims priority to German Patent Application No. DE 102005033983, which was filed in Germany on Jul. 21, 2005, and which are both herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a control element for a motor vehicle, particularly a rotary actuator, including at least one pivoted control knob, an extension formed on the control knob, and an electrical means to detect the rotary movement of the control knob, whereby the electric means works together with the control knob extension. 
     2. Description of the Background Art 
     Highly different systems are prior in the art to detect rotary movements at a rotary actuator in a motor vehicle. Thus, German Unexamined Pat. Application No. DE 103 04 804 A1 describes an electric switch, especially a joystick type switch or cursor type switch, which is also provided with means to detect a rotation of an operating element of the electric switch. On the pivoted operating element an extension is integrally formed at whose end tooth elements are formed in the shape of castle battlements. The tooth elements in this case act together with two light barriers, whose light is interrupted by the tooth elements during rotation of the operating element so that the movement is detectable. The two light barriers are arranged in such a way that the particular rotational direction of the operating element is detectable. It can be derived from the description that other sensory operating switching elements such as Hall sensors may also be used. 
     The use of Hall sensors to detect motion in a switch is described in German Utility Model No. DE 94 15 257 U1. A ferromagnetic object, located centrally above two Hall generators, is affixed on a lock cylinder. If rotation now occurs at the lock cylinder, then a tripping portion is moved to an off-center position relative to a Hall difference IC. In this position, a difference in the magnetic flux between the two Hall generators is perceived. Depending on whether the tripping portion is off-center to the left or right, the difference in the magnetic flux is positive or negative. Therefore, the use of Hall generators in combination with a ferromagnetic object and a permanent magnet is described. 
     German Utility Model No. DE 20 2005 019 271 U1 describes the use of Hall sensor elements to detect movement in a multi-stage contactless switch, particularly for a control element in a motor vehicle. A two-pole permanent magnet is disposed rotated around its central axis to a sensor axis on which the Hall sensors are attached. By means of a movement of the permanent magnet in relation to the sensor axis, the magnetic field detectable by the Hall sensors changes, so that a switching process is detectable. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a control element that, on the one hand, enables the detection of the rotary movement and, on the other, is resistant to soiling, particularly dust. In addition, the operating element is to be made simple in structural terms, smooth-running, and economical to produce. 
     The object of the invention is attained in that the electrical means to detect the rotary movement of the control knob is formed of at least two oppositely polarized magnets, connected torsion-proof to the extension, and at least two sensors, held stationary in the control element and detecting the magnetic field lines of the magnets. The structure of the control element of the invention now makes it possible to provide a control element resistant to soiling. The magnets formed in the extension of the control knob work together with Hall sensors, which enable detection of the rotary movement regardless of dust and dirt. If the sensors detecting the magnetic field lines of the magnets are now disposed below the control knob in such a way that a different switch position is detectable for each rotary movement, determination of the direction of the rotary movement is thus possible simultaneously. The structurally simple layout results from the fact that the extension, formed on the control knob and in which the permanent magnets are contained, is formed as one piece to the extension. It is proposed in another advantageous embodiment to mount the control knob in its seat by means of a conventional, standardized mount, so that, in one respect, free movement is assured and the control element can be manufactured economically with the use of standardized parts. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
         FIG. 1  shows a rotary actuator of the invention in the side view, which is cut in part; 
         FIG. 2  shows a basic view from the direction of arrow II of  FIG. 1 ; 
         FIG. 3  shows an arrangement of the magnets in the extension of the control knob; 
         FIG. 4  shows the course of the switching states determined by the sensors as a function 
       of the rotation angle of the control knob; and 
         FIG. 5  shows the actual course of the field strengths measured by tests and their course 
       versus the rotation angle. 
     
    
    
     DETAILED DESCRIPTION 
     Control element  1  equipped according to the invention is shown in the side view in  FIG. 1  in a partially cut view. The control element in this case includes a control knob  2 , an extension  3 , formed on control knob  2 , of a seat  4  arranged in a torsion-proof manner in control element  1  for control knob  2 , whereby the seat is attached to a printed circuit board  5 . A sensor  7 , which detects the magnetic field lines of the magnets and in this exemplary embodiment is a Hall sensor, is attached to printed circuit board  5  in a recess  6  of seat  4 . Control knob  2  is mounted by means of a mount  8  in seat  4 . A detent contour  9 , which works together with spring element  10  generating the detent force, is formed simultaneously on the control knob  2 . Of course, detent contour  9  and detent spring  10  are also attached or formable the other way around in the control element. An area  11 , in which the magnets are held, is formed or attached in each case torsion-proof at the lower end of extension  3 . Extension  3  and seat  4  are shown in section, whereas control knob  2  is shown from its side, so that grip area  2  detectable for a user can be seen. Grip area  2  may be made, of course, also of several parts, for example, of a metallic or a metallic two-component plastic and a rubber-elastic surface. As indicated by the broken lines  12 , both control knob  2  and seat  4  are made hollow, so that internal part  13 , as also extension  3 , form hollow-cylinder-shaped parts  3 ,  13 . 
     If control knob  2  is now moved around its central axis  14  in the direction of arrow P, a relative movement occurs between control knob  2  and seat  4  held rigidly in control element  1 . As a result, a freely selectable detent is created simultaneously via detent contour  4  and detent spring  10 , whereby the rotary movement occurs over mount  8 . Part  11 , provided with magnets, of extension  3  moves here over Hall sensors  7 , whereby preferably two Hall sensors  7 ,  15  are used, as is also evident from  FIG. 2 . Preferably, two detents, distributed in each case along the periphery, are assigned to a magnetized area  16  or  17 . 
     Further, the interplay between Hall sensors  7 ,  15  and the oppositely polarized magnets  16 ,  17  is described for a more detailed explanation of the mode of operation of the direction determination and the detection of the switch position.  FIG. 2  depicts a basic view from the direction of arrow II of  FIG. 1 . Hall sensors  7 ,  15  and a section from extension  3 ,  11  of control knob  2  can be seen. The arrows  18  indicate the position of the detents, i.e., the individual detent positions during rotation. Permanent magnets  16 ,  17  are arranged next to one another in extension  3 ,  11  with different polarities. Thus, it is conceivable, for example, to provide the lighter area  16  with a positive pole and the darker area  17  with a negative pole. It is important here that Hall sensors  7 ,  15  can detect a magnetic flux difference in the positive or negative direction from the different polarity to enable therewith an evaluation of the rotation direction and the rotary movement. If the positive magnetization of magnet  16  is now designated as north, the negative polarity of magnet  17  can be designated as south. A complete arrangement of magnets  16 ,  17  with their north and south poles is shown in  FIG. 3 . It is particularly advantageous here, as shown in  FIG. 3 , that the magnets do not completely fill areas  16 ,  17 , but that it suffices when area  11 , provided with the magnets, is only partially provided with magnets  16 ,  17 . The alternating polarity is essential, however. 
     A course of detected switching states of Hall sensors  7 ,  15  as a function of the rotation angle and the individual detent positions  18  is shown in  FIG. 4 . Proceeding from position  19 , which is shown in  FIG. 2  and is characterized in that both Hall sensors are above a north pole  16 , in a subsequent switch each time a  1  is determined as north pole  16 , so that switching state  1 / 1  results. If control knob  2  is now moved in the direction of arrow F, the polarity above Hall sensor  15  changes from north  16  to south  17  and therefore from plus to minus. This corresponds to switch position  20  of  FIG. 4 , in which the switching state  1 / 0  is detectable. The detection of the rotation direction is made possible by this type of arrangement of Hall sensors  7 ,  15  relative to permanent magnets  16 ,  17 . As depicted by way of example,  FIG. 4  shows the course of the switching states of Hall sensors  7 ,  15 , whereby the change in the field line strength of the permanent magnets is detected by means of Hall sensors  7 ,  15 . Switching states  19 ,  20  are shown in  FIG. 4  versus rotation angle  21 , the rotation angle forming the ordinate of the diagram. 
     The actual course of the switching states in an exemplary embodiment of a control element  1  of the invention is depicted in  FIG. 5 . In this case, the ordinate  22  again designates the rotation angle from 0° to 360° and the corresponding measured value  23 ,  24  for the determined field line strength of permanent magnets  16 ,  17  is shown on the abscissa  23 . In the actual course of the measured values  23 ,  24  of the Hall sensors, which correspond to a sinusoidal wave, the switching states  25 ,  26  resulting therefrom, as they are depicted in  FIG. 4 , are shown superimposed. Here, the course of curve  23  corresponds to switching state  25  of Hall sensor  15  and the course of curve  24  to switching state  26  of Hall sensor  7 . The two switching states  25 ,  26 , described in  FIG. 4  according to the exemplary embodiment, were also entered in  FIG. 5 . It can be seen that to achieve a switching threshold a certain threshold value  27 ,  28  must be exceeded or underrun. 
     Hall sensors  7 ,  15  are placed directly on the present printed circuit board  5 . To minimize the tolerances, printed circuit board  5  is oriented by means of auxiliary pivots to rotary actuator  1 . It must be noted furthermore that Hall sensors  7 ,  15  may also be used, which are mounted vertically on printed circuit board  5  and therewith stand opposite at the periphery to extension  3 ,  11  and corresponding magnets  16 ,  17 . 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.