Abstract:
A disk mountable on a rotating support has one side at least partially covered with an elastomer loaded with magnetic particles to form an encoder while the other side of said disk axially limits an annular chamber. A sealing structure attached to the disk and contained within the plane of a lateral side of a support capable of supporting a non-rotating component of the seal with incorporated encoder is mountable within an annular cavity which is axially limited by the plane.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to encoder mounting devices and, more particularly, to a seal incorporating an encoder with multipolar magnetization for generating a magnetic field. 
     Document EP A 495323 describes a seal which has a rotating deflector covered by or made of a magnetized material. 
     When the operation of a particular sensor requires a strong magnetic field, the axial space requirement of the encoder must be increased. According to document FR A 2660975, the internal side of a rotating disk is oriented toward a sealing fixture, while the external side of the disk supports an encoder. The total axial dimension of such a seal does not allow sealing of bearings whose axial space requirements are determined in advance. 
     The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one, or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, this is accomplished by providing a seal with incorporated encoder. A disk mountable on a rotating support has an elastomer loaded with magnetic particles covering at least a portion of a first side of the disk to provide an encoder while the second side of the disk axially limits an annular chamber. A sealing means attached to the disk is contained within the plane of a lateral side of a support capable of supporting a non-rotating element of the seal mountable in an annular cavity axially limited by said plane. 
     The foregoing and other aspects of the invention will become apparent from the following detailed description thereof when considered, in conjunction with the accompanying drawing figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a radial cross-sectional view of a seal with incorporated encoder mounted on a rotatable shaft, illustrating an embodiment of the present invention; 
     FIG. 2 is a radial cross-sectional view similar to FIG. 1 illustrating a second embodiment of the Seal with incorporated encoder of the present invention; 
     FIG. 3 is a radial cross-sectional view similar to FIG. 1 illustrating a flush-fit seal rib with encoder between outer and inner rings of a rolling bearing; 
     FIG. 4 is a radial cross-sectional view illustrating a fourth embodiment of the present invention similar to that of FIG. 3; 
     FIG. 5 is a radial cross-sectional view illustrating a fifth embodiment of the present invention similar to that of FIG. 3; 
     FIG. 6 is a radial cross-sectional view similar to FIG. 1 illustrating a simplified sixth embodiment of the present invention; and 
     FIG. 7 is a radial cross-sectional view illustrating a seventh embodiment of the present invention similar to that of FIG. 6. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, FIGS. 1 and 2 show a rotating support shaft 1 supporting a radial disk 2 which is firmly attached to a cylindrical bearing surface 3 which is fitted to shaft 1. One side of disk 2 is covered with an elastomer loaded with magnetic particles, the elastomer and magnetic particles being designated as an encoder element 4. Disk 2 can also be made of a magnetic material for the purpose of ensuring a concentration of the field and of the magnetic flux emitted by encoder element 4. 
     Disk 2 and cylindrical bearing surface 3 together constitute an internal reinforcement located within a fixed external reinforcement 5, mounted on a support 6. External reinforcement 5 also has a mounting bearing surface 7 flush-fit in support 6 and a fixed radial disk 8 oriented toward the axis of rotation of shaft 1. 
     Disk 8 has an elastomeric coating 10 which has an axial lip 11 and a radial lip 11&#39; bearing against the free side of disk 2 and against the external surface of bearing surface 3, respectively, for sealing the bearing. The boundary of coating 10 connected to mounting bearing surface 7 has a circular rib 12 flush-fit in a countersink or on a chamfer of support 6. The external lateral surface of disk 2 is connected to a radial sealing lip 13 merging with shaft 1 and contained within the plane P of lateral side 61 of support 6. 
     Disks 2 and 8, encoder element 4, and elastomeric coating 10 are mounted within an annular cavity 15 which is axially limited by the plane P. In the embodiment of FIG. 1, the peripheral surfaces of disk 2 and encoder element 4 are separated radially from elastomeric coating 10 by an interstice 16. However, the peripheral surfaces of disk 2 and encoder element 4 can be flush-fit under a fixed sealing lip 17 supported by coating 10 and in contact with encoder element 4, as shown in FIG. 2. 
     Moreover, disks 2 and 8 of FIG. 2 delimit annular cavities 19 and 29 which may be filled with a magnetic liquid kept in place by the magnetism of encoder element 4. This liquid may also be contained within the interstice 16. The presence of liquid loaded with ferrite improves the sealing property of the seal. The encoder incorporated with the seal should however have a sufficiently large volume so that the magnetic field can be read easily by a sensor. 
     FIGS. 3 through 7 illustrate variations of the seal with incorporated encoder illustrated in FIGS. 1 and 2. The elements and parts of the assembly shown in FIGS. 3 through 7 whose functions correspond to the elements and parts illustrated in FIGS. 1 and 2 are consequently identified by the same reference numerals. In each of the embodiments, the external lateral side of encoder 4 essentially merges with plane P of the lateral side of outer ring 30 supporting disk 8. 
     The seal illustrated in FIGS. 3 and 4 is mounted in a cavity delimited between the support rings, that is, rotating inner ring 20 and fixed outer ring 30 of a bearing with rolling elements. For this purpose, encoder element 4 on disk 2 is limited radially in its internal diameter by an annular sealing rib 21 intended for the mounting of encoder element 4 in an annular groove 22 of inner ring 20. In a similar manner, elastomeric coating 10 on disk 8 is limited radially at its external diameter by an annular sealing rib 31 intended for the mounting of disk 8 in an annular groove 32 of outer ring 30. 
     According to FIG. 3, the peripheral surface of the encoder-disk combination 2,4 is separated radially by an interstice 16 from outer ring 30 of the bearing. According to FIG. 4, the axial dimensions of interstice 16 are limited by a lip 33 which extends radially outward at the perimeter of encoder 4. Annular rib 21 consists of an elastomer which is not loaded with ferrite. 
     FIG. 5 illustrates an embodiment of the present invention corresponding to the structure described with reference to FIG. 3 and in which annular sealing rib 21 consists of an elastomer which is not loaded with ferrite. In the embodiment of FIG. 5, disk 8, which supports elastomeric coating 10 and includes sealing lips 11,11&#39; corresponds to the structure described with reference to FIG. 1 in which radial lip 11&#39; bears, for example, against rotating inner ring 20 of a bearing. 
     FIG. 6 illustrates a simplified embodiment of the present invention which is mounted on a fixed inner ring 20 and a rotating outer ring 30 of a rolling bearing. Disk 2 is extended to the outside by mounting cylindrical bearing surface 3 in cavity 15 delimited between inner and outer rings 20,30 and the plane P of the lateral side of the bearing. Encoder element 4 supports an external radial sealing lip 33 in contact with a cylindrical bore of outer ring 30 and radial lip 34 in contact with a conical bearing surface of inner ring 20. 
     FIG. 7 illustrates a simplified embodiment of the present invention similar to that of FIG. 6 between a fixed inner ring 20 and a rotating outer ring 30 of a rolling bearing. In this example, a lateral side of encoder element 4 essentially merges with the plane P of the lateral side of the bearing. Disk 2 supports an elastomeric seal, which is of a known type, with two radial lips 35, bearing against inner ring 20 due to the action of a spring. 
     The present invention thus provides a rolling bearing with an encoder mounting means such that the axial position of the seal has no effect on the overall dimension of the bearing. The invention also provides a rolling bearing seal whose sealing property is improved at the connections with the fixed and mobile elements of the bearing. In addition, the invention provides a compact seal assembly comprising a sealing fixture with flexible lips whose incorporated encoder can easily be manufactured from an elastomer loaded with ferrite particles.