Patent Publication Number: US-2012027329-A1

Title: Flange assembly

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a flange assembly for holding a portion of a rotatable shaft. 
     BACKGROUND ART OF THE INVENTION 
     EP-A-1 705 089 describes a flange assembly comprising a ball bearing, a target attached to an inner ring of the ball bearing, a sensor and a flange for securing the outer ring of the ball bearing to a static casing. In the flange assembly, the sensor can hardly be removed in order to be replaced or repaired. Furthermore, the ball bearing of the flange assembly of EP-A-1 705 089 has a relatively low service life due to the axial clearance between rotating parts and static parts. Besides, the sensor and the target may have separate movements, such that the sensing gap between them varies, thus lowering the sensor accuracy. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to solve the here-above described problems by providing a flange assembly enabling access to the sensor, hence a high serviceability, and allowing axial preloading of the rolling bearing. 
     This object is achieved by a flange assembly, for holding a portion of a rotatable shaft, comprising:
         a rolling bearing having an inner ring and an outer ring, said inner ring being rotatable around an axis of rotation,   a target attached to said inner ring,   a sensing element arranged to read said target,   a flange having securing means for securing said flange assembly to a static casing.
 
This flange assembly is characterized in that it further comprises:
   a holding part configured to hold said outer ring,   a resilient part arranged to elastically urge said holding part with respect to said securing means and generally along said axis of rotation,
 
Furthermore, said sensing element is attached to said holding part so as to be removable from outside said static casing.
       

     Thanks to the invention, the sensor is easily removable, the rolling bearing can be preloaded and the sensor and the target move together without significantly varying the sensing gap between them. 
     According to other advantageous but optional features of the present invention, considered either in isolation or in any technically feasible combination:
         said resilient part is integral with said flange;   said holding part is integral with said flange;   said securing means, said resilient part and said holding part are integral, in that said flange has a rotational symmetry and in that said resilient part comprises an annular ridge joining said securing means and said holding part;   said annular ridge has a cross-section, along a plane comprising said axis of rotation, having the shape of half an ellipse.   said holding part has a hole, said sensing element being mounted through said hole;   said sensing element is arranged to be mounted on or removed from said holding part along a generally radial direction with respect to said axis of rotation;   said sensing element is individually removable from said flange assembly;   said holding part encases said outer ring;   said securing means comprise an annular plate and a plurality of holes bored through said annular plate;   said sensing element is arranged to read said target along a radial direction with respect to said axis of rotation;   said sensing element is arranged to read said target along an axial direction with respect to said axis of rotation;   said sensing element is selected in the group comprising a magnetic sensor, a capacitive sensor, an inductive sensor and an optical sensor; and   said resilient part comprises an elastic washer.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention and its advantages will be well understood on the basis of the following description, which is given as an illustrative example without restricting the scope of the invention and in relation with the annexed drawings, among which: 
         FIG. 1  is a perspective view of a flange assembly according to the invention, 
         FIG. 2  is an exploded perspective view of the flange assembly of  FIG. 1 , and 
         FIG. 3  is a cross-section along plane III on  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF SOME EMBODIMENTS 
       FIGS. 1 and 2  illustrate a flange assembly  1 , respectively after and before its assembly. Flange assembly  1  comprises a rolling bearing  3 , a flange  4  and a sensing element or sensor  7 . Flange  4  has a rotational symmetry around axis X 3 -X′ 3 . 
     The rolling bearing  3  has balls  33 , an inner ring  31  and an outer ring  32 . Inner ring  31  is rotatable around an axis of rotation X 3 -X′ 3 . The annular, inner radial surface of inner ring  31  receives an end portion of a rotatable shaft  2 . Rolling bearing  3  is mounted into flange  4 . 
     Flange assembly  1  further comprises a holding part  43  to hold rolling bearing  3  and sensor  7 . As can be seen on  FIG. 2 , holding part  43  has a cavity  45  of a cylindrical shape to encase the annular, radial outer surface of the outer ring  32 . Holding part  43  thus encases the outer ring  32 . 
     Flange  4  comprises a plate  41  of a flat, annular shape extending radially with respect to axis X 3 -X′ 3 , i.e. along an axis Y 3 -Y′ 3 . On the side of axis X 3 -X′ 3 , plate  41  ends up with a shoulder  411  serving as a positioning reference. Flange  4  also comprises several holes  42  bored through plate  41  at locations which are approximately evenly distributed around axis X 3 -X′ 3 . The holes  42  are bored parallel to axis X 3 -X′ 3 . 
     Plate  41  and holes  42  form securing means for securing flange assembly  1  to a static casing C, partially sketched by a dashed line at  FIG. 3 . Such a static casing C is intended to house the rotatable shaft  2 . For instance, such a static casing C can be a motor casing for housing a motor, or any other mechanical system such as a gearbox or an actuator. 
     In order to secure flange  4  to the static casing C, plate  41  can be pressed against a not shown corresponding plate, while screws or bolts, schematically shown at  FIG. 3  with reference X C -X′ C , pass through the holes  42  to fasten flange assembly  1  to the static casing C. Holding part  43  is hence configured to hold the outer ring  32 . 
     Sensor  7  comprises an electrical connector  72  and a sensing member  71 . As can be seen on  FIG. 3 , after assembly of flange assembly  1 , sensing member  71  is arranged to read a target  51 . In the example of the  FIGS. 1 ,  2  and  3 , the sensor  7  is of a magnetic type. The sensing member  71  can comprise a Hall effect cell and the target  51  can be a magnetized multipolar ring. Connector  72  can receive a plug not shown to supply electrical power to the sensing member  71  and deliver sensing signals to a not shown remote control unit. 
     Sensor  7  is mounted through a hole  47  visible on  FIG. 2 . Hole  47  is bored through an exterior portion  46  of holding part  43  along a radial direction Y 3 -Y′ 3  with respect to axis X 3 -X′ 3 . Sensor  7  is arranged to be mounted on or removed from holding part  43  along radial direction Y 3 -Y′ 3 . As can be seen on  FIGS. 1 and 2 , connector  72  of sensor  7  is fastened to the exterior portion  46  by means of two screws  73  and  74 . The terms “interior” and “exterior” respectively refer to the inside and to the outside of the static casing C. The term “inner” relates to an element oriented towards axis X 3 -X′ 3 , whereas the term “outer” relates to an element oriented opposite to axis X 3 -X′ 3 . 
     Sensor  7  is individually removable from flange assembly  1 , i.e. without removing any other component of flange assembly  1 . Besides, in order to remove sensor  7  from outside the static casing C, an operator only needs to unscrew screws  73  and  74 . Alternatively to screws, snapping means can advantageously be used to lock the sensor  7  in position. Sensor  7  is thus easily removable from outside the static casing C. The outside of the static casing C is represented by the right-hand part of  FIG. 3 . 
     The target  51  is attached to the inner ring  31 . More accurately, target  51  is fixed on a support member  5 , which is fast with inner ring  31 . Target  51  can be stuck or tight-fitted onto the radial outer surface of support member  5 . Thus, the sensing member  71  of the sensor  7  is arranged to read target  51  along a radial direction with respect to axis X 3 -X′ 3 . The sensor therefore measures a rotational parameter of the flange assembly. 
     Flange assembly  1  further comprises an annular ridge  44  joining the plate  41  and the holding part  43 . Like the flange  4 , the annular ridge  44  has a rotational symmetry around axis X 3 -X′ 3 . The cross-section of annular ridge  44  along plane Ill has the shape of half an ellipse. The plate  41 , the annular ridge  44  and the holding part  43  are integral. Therefore, annular ridge  44  is integral with flange and holding part  43  is integral with flange  4 . 
     The dimensions of annular ridge  44 , in particular its thickness along axis X 3 -X′ 3 , are selected so that the annular ridge  44  can have an elastic deformation along axis X 3 -X′ 3 , as indicated by the double arrow D 44  at  FIG. 3 . The annular ridge  44  thus forms a resilient part arranged to elastically urge holding part  43  with respect to plate  41  and holes  42  and generally along axis X 3 -X′ 3 . 
     Annular ridge  44  hence enables to preload the rolling bearing  3 , in particular its outer ring  32 . Such a preloading of rolling bearing  3  permits to avoid any unnecessary clearance inside the bearing, so that the bearing rotates smoothly and quietly. For instance, in case the rolling bearing  3  is a Deep Groove Ball Bearing, a flange assembly according to the invention ensures that a small axial preloading is applied onto the bearing. 
     Flange assembly  1  further comprises a sealing gasket  6  mounted into the outside portion of holding part  43  so as to hinder leaks of lubricant out of the static casing and to prevent ingress of water or dust in the static casing. 
     Thus, a flange assembly according to the invention provides easy access to the sensor for its removal or replacement, hence a high serviceability of the sensor. 
     Furthermore, a flange assembly according to the invention permits to preload the rolling bearing, hence to increase its service life. 
     Besides, since the sensor and the target are both fixed with respect to the holding part, they move together without significantly varying the sensing gap between them. This increases the sensor accuracy, and thereby the precision of the measurement. 
     According to a not shown embodiment, the resilient part can comprise an elastic washer forming a resilient part, instead of annular ridge  44 . Such an elastic washer can be located between the securing means, i.e. annular plate and the static casing. 
     Alternatively to a magnetic encoder, the sensor can be selected in the group consisting of a capacitive sensor, an inductive sensor and an optical sensor. 
     According to a not shown embodiment of the present invention, the sensor can comprise several sensing members and can be arranged to read one or several targets along an axial direction or along a direction sloped to the axis of rotation. 
     According to another not shown embodiment, a flange assembly according to the present invention can comprise a blind plummer block to receive the end of a shaft so as to form a flange corresponding to the flange  4 . 
     According to a further not shown embodiment of the present invention, the flange assembly can house a middle portion of a shaft, instead of the end of a shaft. 
     The invention has been described in relation with a rolling bearing having balls as rolling components. However, the invention also applies to other types of rolling components, like rollers or needles for instance.