Rolling bearing unit with rotation speed detection instrument for use in cars and method for working outer race for use in this bearing unit

Abstract

A rolling bearing unit with a rotation speed detection instrument having a hub with a plurality of inner race tracks, an outer race formed of steel material with a plurality of outer race tracks, rolling elements between the tracks, and encoder on the hub and a sensor supported in a mounting hole in the outer race. A hardened layer is formed on the inner surface of the outer race and each portion where the outer race tracks are formed. An area of the inner surface around the mounting hole is not hardened.

What is claimed is  
     
         1 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race formed of steel material, which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface which face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and the corresponding outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals; and    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder,    wherein a hardened layer is formed in the inner surface of the outer race, and each portion where the outer race track is formed, and a distance between an end periphery of the outer race, track which is closer to said mounting hole and the mounting hole is 10.5 mm or less, and a portion where said mounting hole is formed is not hardened and a thickness of the hardened layer formed in the outer race track closest to said mounting hole is 1.5 mm or more.    
     
     
         2 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race formed of steel material, which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface which face the inner racetracks;    rolling elements, each being rotatably provided between the inner race track and the outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals;    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section face the encoder and changing its output signal in response to the change of the characteristic of the encoder; and    a hardened layer exhibiting a hardness of 500 Hv or more, being formed in the inner surface of the outer race and at each portion where the outer race track is formed,    wherein a distance between the mounting hole and an end periphery of the outer race track closest to the mounting hole among said outer race tracks is at a range from 2 to 10.5 mm, and a minimum distance between said mounting hole and the hardened layer is 0.5 mm or more.    
     
     
         3 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface;    an outer race formed of steel material, which is supported by a suspension device and does not rotates at the time of its use, the outer race having plural lines of outer race tracks in an inner peripheral surface which face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and the corresponding outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals;    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder, and    a hardened layer being formed in the inner surface of the outer race and at each portion where the outer race is formed, and    wherein the hardened layers provided in the outer race track portions are connected to each other by a jointing hardened layer provided apart from said mounting hole in its circumference direction, and a portion of said outer race at which said mounting hole is formed is not hardened.    
     
     
         4 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race formed of steel material, which is supported by suspension device and does not rotates at the time of its use, the outer race having plural lines of outer race tracks in an inner peripheral surface which face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and the outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals; and    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder; and    a hardened layer exhibiting a hardness of 500 Hv or more is formed in the inner surface of the outer race, and at each portion where the outer race track is formed    wherein the hardened layers provided in the outer race track portions are connected to each other by a jointing hardened layer exhibiting a hardness of 500 Hv or more provided apart from said mounting hole in its circumference direction, and a minimum distance between said mounting hole and the jointing hardened layer is 0.5 mm or more.    
     
     
         5 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface to face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and the corresponding outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals; and    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder, and    a hardened layer being formed in the portions where the outer race tracks are formed and a portion between the outer race tracks, in the inner peripheral surface of said outer race,    wherein said mounting hole is one formed using a drill having a super-hard drill or a ceramic chip, while cooling and lubricating a cut portion by cutting oil.    
     
     
         6 . A method for working the outer race constituting the rolling bearing unit according to  claim 5 , comprising the steps of: 
 forming the hardened layer in the inner peripheral surface of the outer race and in the portions of each outer race track and the portion between the outer race tracks; and    forming the mounting hole in a portion of the outer race track in an intermediate portion of the outer race in its axial direction using the drill having the super-hard drill or the ceramic chip, while cooling and lubricating the cut portion by cutting oil.    
     
     
         7 . The method for working the rolling bearing unit according to  claim 6 , wherein the hardened layer located in the inner peripheral surface of the outer race and in the portion where each outer race track is formed and the portion between the outer race tracks is formed while cooling said outer race from the outer peripheral surface side by coolant, and a cutting speed for making the mounting hole by the drill is 20 m/min. or less expressed by a speed of an outer peripheral surface of the drill.  
     
     
         8 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface to face the inner race tracks;    rolling elements,, each being rotatably provided between the inner race track and corresponding the outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals; and    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder,    wherein a hardened layer is one formed by heating the inner peripheral surface of said outer race while cooling said outer race from its outer peripheral surface side by coolant, after said mounting hole has been formed from the outer peripheral surface of said outer race to a certain portion in a diameter direction of said outer race, and the said mounting hole is one completed by perforating through the certain portion to the inner peripheral surface of said outer race.    
     
     
         9 . The method for working the outer race constituting the rolling bearing unit according to  claim 8 , wherein the hardened layer is formed by heating the inner peripheral surface of said outer race while cooling said outer race from its outer peripheral surface side by coolant, after said mounting hole is formed from the outer peripheral surface of said outer race to a certain portion in a diameter direction of said outer race, and then the said mounting hole is completed by perforating through the certain portion to the inner peripheral surface of said outer race.  
     
     
         10 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface to face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and the corresponding outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals;    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial, direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder; and    a hardened layer being formed in the portions where the outer race tracks are formed and a portion between the outer race tracks, in the inner peripheral surface of said outer race, and    wherein after said mounting hole is formed, said the hardened layer is formed by heating the inner peripheral surface of said outer race while cooling the outer peripheral surface of said outer race by coolant in state where the mounting hole is at least substantially sealed by a plug.    
     
     
         11 . The method for working the outer race constituting the rolling bearing unit according to  claim 10 , wherein after the mounting hole is formed at a portion between the outer race tracks and in an intermediate portion of said outer race in its axial direction, said the hardened layer is formed by heating the inner peripheral surface of said outer race while cooling the outer peripheral surface of said outer race by coolant in a state where the mounting hole is at least substantially sealed by a plug.  
     
     
         12 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface thereof;    an outer race which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface to face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and the corresponding outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately so equal intervals;    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder; and    a hardened layer being formed in the portions where the outer race tracks are formed and a portion between the outer race tracks, in the inner peripheral surface of said outer race, and    wherein after said mounting hole is formed, said hardened layer is formed by, while rotating said outer race, heating the inner peripheral surface of the outer race while cooling the outer peripheral surface of said outer race by coolant blown upward.    
     
     
         13 . The method for working the outer race constituting the rolling bearing unit according to  claim 12 , wherein after the mounting hole is, formed at a portion between the outer race tracks in an intermediate portion of said outer race in its axial direction, said hardened layer is formed by, while rotating the outer race, heating the inner peripheral surface of the outer race while cooling the outer peripheral surface of said outer race by coolant blown upward.  
     
     
         14 . A rolling bearing unit with a rotation speed detection instrument comprising; 
 a hub rotating together with a wheel at the time of its use, the hub having a plurality of inner race tracks in an outer peripheral surface;    an outer race which is supported by a suspension device and does not rotates at the time of its use, the outer race having a plurality of outer race tracks in an inner peripheral surface to face the inner race tracks;    rolling elements, each being rotatably provided between the inner race track and corresponding the outer race track;    an encoder fixedly provided at a portion of the outer peripheral surface of the hub between the inner race tracks, the encoder exhibiting a characteristic which changes in its circumference direction alternately at equal intervals; and    a sensor having a detecting section, the sensor being supported in a mounting hole provided in an intermediate portion of the outer race in its axial direction so that the detecting section may face the encoder and changing its output signal in response to the change of the characteristic of the encoder; and    wherein a hardened layer being formed in the portion where the outer race tracks are formed and a portion between the outer race tracks, in the inner peripheral surface of said outer race,    wherein after said mounting hole is formed, said hardened layer is one formed by heating the inner peripheral surface of the outer race while cooling the outer peripheral surface of said outer race by gaseous coolant.    
     
     
         15 . The method for working the outer race constituting the rolling bearing unit according to  claim 14 , wherein after the mounting hole is formed at a portion between the outer race tracks and in an intermediate portion of said outer race in its axial direction, said hardened layer is formed by heating the inner peripheral surface of the outer race while cooling the outer peripheral surface of said outer race by gaseous coolant.