Abstract:
A motor includes a magnetic ring which is the seat of a magnetic field related to operating parameters of the motor. A connector for the motor includes a magnetic flux conduction member forming a flux concentrator interposed, when the connector is fixed on the motor, between the magnetic ring and a Hall-effect sensor adapted so as to measure the magnetic flux the magnetic flux conduction member. Application to geared motors for window-raising systems, seat actuation systems or sunroof systems, in the automobile sector.

Description:
BACKGROUND OF THE INVENTION 
     The present invention concerns the domain of electric motors, in particular geared motors for automobile accessories, which are used for example in window-raising systems, seat actuation systems or sunroof systems. 
     The invention is more precisely aimed at a connector for electric motor, adapted so as to be fixed on said motor, said motor comprising a magnetic ring which is the seat of a magnetic field related to operating parameters of the motor. 
     The motors or geared motors to which the invention applies are associated with a control system which uses motor speed and/or position parameters. These parameters are fed to the control system by a Hall-effect sensor associated with the magnetic ring, which is adapted so as to deliver to the sensor a magnetic field dependant on the speed and/or position of the motor shaft. 
     Generally, the electronic control devices of such motors or geared motors comprise an electronic board secured to the casing of the motor, said board comprising motor electrical supply connections and the Hall-effect sensor. This sensor is fixed on a board part formed of a rigid strip penetrating the casing of the motor as far as a zone neighboring the magnetic ring, in such a way that the sensor is located in the vicinity of said ring. 
     It is understood that the presence of such an electronic control module on the casing of the motor is incompatible with a high degree of standardization of motors, since such a configuration of the motor and of its casing is not suited to an application in which the speed and/or position sensor is dispensed with, and in which the electronic control device of the motor is located off-site some distance away from the motor. 
     SUMMARY OF INVENTION 
     A main aim of the invention is to remedy this drawback, and to propose a connector for electric motor, which makes it possible to transport information of magnetic type to an electronic processing device and is capable of amalgamating with this function the conventional functions for the electrical supply of the motor. 
     With this aim, a connector according to the invention comprises at least one magnetic flux conduction member forming a flux concentrator interposed, when the connector is fixed on the motor, between the magnetic ring and a Hall-effect sensor adapted so as to measure the magnetic flux conducted by the magnetic flux conduction member. 
     The invention is also aimed at a geared motor for automobile accessories, such as a window or a seat, comprising a rotor shaft equipped with a magnetic ring, characterized in that it comprises a connector as described above. 
     BRIEF DESCRIPTION OF DRAWINGS 
     Exemplary embodiments of the invention will now be described with regard to the appended drawings, in which: 
     FIG. 1 is an end-on view in partial section of a geared motor equipped with a connector according to a first embodiment of the invention; 
     FIG. 2 is a diagrammatic cross section along the line  2 — 2  of FIG. 1 representing the magnetic flux conduction member and the magnetic ring; 
     FIG. 3 is a view similar to FIG. 1 according to a second embodiment of the invention; 
     FIG. 4 is a cross section similar to FIG. 2, along the line  4 — 4  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Represented in FIG. 1 is a geared motor  1  essentially consisting of a motor  2  and of a reduction gear  3 , the motor  2  being equipped with an electronic control device  4  which comprises a printed circuit board  5 . 
     The motor  2  comprises a stator  6  forming a shroud in which are housed permanent magnets (not represented), and supporting by way of a bearing  7  an end  8 A of a shaft  8  of a rotor  9 . In a known manner, the latter comprises windings coiled around stacked laminations. A commutator  10  is linked electrically to the rotor  9  and receives by way of brushes  1  the motor supply current transmitted to said motor at the level of supply lugs  12 . 
     The geared motor  1  moreover comprises a casing  20  rigidly fixed to the stator  6  and supporting by way of a second bearing assembly, not represented, the second end of the rotor shaft  8 . The rotor shaft span situated on the same side as this second shaft end is configured as a threaded rod forming a worm screw, which drives a set of gears of the reduction gear  3 . 
     A magnetic ring  21  is fixed on the rotor shaft  8  in a region neighboring the supply lugs  12 . 
     The casing  20  exhibits an aperture  22  in proximity to the supply lugs  12 , which aperture is adapted so as to receive in a detachable manner an electrical connector  30  into which the printed circuit board  5  of the electronic control device  4  is fixed. This board supports an electronic circuit  100  able to deliver a supply current for the motor. The connector  30  is held in position by releasable fastening means of conventional type (not represented). The current delivered by the electronic circuit  100  travels through power tags  31  secured to the printed circuit board  5 , each of said tags  31  being connected fixedly to an end  32 A of a contact  32  of “stirrup” type, that is to say a contact one end of which consists of an elastic clip having two inwardly arched symmetric contact portions. 
     The printed circuit board  5  additionally supports a Hall-effect sensor  33  intended to receive a magnetic flux indicative of the speed and/or position of the rotor shaft  8  and to transmit to the electronic control device  4  an electrical signal indicative of these operating parameters of the motor. 
     The connector  30  also comprises a magnetic flux conduction member  35  consisting, in the variant of the invention represented in FIG. 1, of two parallel metal pins, one end of which is fixed to the printed circuit board  5  in the vicinity of the Hall-effect sensor  33 . The other end  35 A constituting the free end of the pin  35  is situated, when the connector  30  is inserted into the aperture  22  of the corresponding casing  20  and held by the fastening means, in proximity to the periphery of the magnetic ring  21 . The two free preferably disposed symmetrically respect to an axial plane P of the magnetic ring  21 . 
     The relative position of the metal pins  35  and of the magnetic ring  21  is more clearly apparent in FIG.  2 . The magnetic ring  21  generates a magnetic field of constant strength whose direction varies with the angular position of the rotor shaft  8 , and therefore the magnetic flux conducted by the pins  35  of the magnetic ring  21  to the Hall-effect sensor  33  is dependent on the angular position of the rotor shaft  8 . The electrical signal delivered by the Hall-effect sensor  33  therefore affords access to the speed and/or angular position of the rotor shaft  8 . 
     Preferably, the pins  35  forming magnetic flux conduction members are made of steel. 
     Represented in FIG. 3 is a geared motor  101  of the same type as above, whose motor  102  comprises a rotor shaft  108  on which a magnetic ring  121  is fixedly mounted. A connector  130  comprises a printed circuit board  105  forming part of an electronic control device  104  of the electric motor  102  and supporting a pair of supply tags  131  situated in proximity to a Hall-effect sensor  133 . The connector is fixed in a detachable manner to the casing  120  of the geared motor  101  by conventional releasable fastening means (not represented). The connector  130  comprises contacts  132  of “stirrup” type, fixed by one of their ends  132 A to the tags  131  and intended to be connected by their second end  132 B to motor supply lugs  112 . 
     In this variant of the invention, and as will be more clearly seen in FIG. 4, the two lugs  112  each exhibit a part  140  overlapping the magnetic ring  121 , oblique with respect to the direction of coupling of the contacts  132 , and which lies in the vicinity of the magnetic ring  121  in an almost tangential manner. These two parts  140  are preferably symmetric with respect to the axial plane P of the ring  121 . Likewise, the tags  131  comprise a part  131 A partially overlapping the Hall-effect sensor  133 , so that the lugs  112 , the contacts  132  and the tags  131  fulfill the flux concentrator function and constitute a member for conducting the magnetic flux of the magnetic ring  121  to the Hall-effect sensor  133 . 
     Preferably, the contacts  132  are made of steel, a material of this type offering an acceptable compromise between the qualities of electrical and magnetic conduction, and exhibiting excellent mechanical properties. 
     It is readily understood that the two variants of the invention which have just been described make it possible to design geared motors with a high degree of standardization. Specifically, it is not necessary to secure a printed circuit board carrying a Hall-effect sensor to the motor in order to achieve the position and/or speed sensor functions, and hence to modify the casing of a standard motor. Thus, one and the same motor can be used regardless of the application of the geared motor, and regardless of the type of sensor required (speed/position), only the connector having to be modified. 
     The invention, which makes it possible to conduct magnetic information to an offsite sensor, renders a single geared motor configuration adaptable to various applications, the standardization of the geared motor being offset by the diversification of the connection engineering, thereby achieving a considerable saving with regard to the complete system. 
     The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specially described. For that reason the following claims should be studied to determine the true scope and content of this invention.