Hub unit for wheel

A hub unit for wheel comprising:

• an outer ring having two bearing tracks on its inner circumferential surface;
• a hub having a wheel mount flange on the outer end side and an end portion on the axially vehicle center side, said hub having, integrally on its outer circumference, a first bearing track corresponding to the axially vehicle outer end side bearing track of said outer ring;
• an inner ring element fitted on said end portion side of said hub, said inner ring element having on its outer circumference a second bearing track opposed to the axially vehicle center side bearing track of said outer ring and being fixed on said end portion by plastically deforming said end portion of said hub radially outwardly by caulking, said inner ring element being formed with a chamfered portion between an inner circumferential surface and a vehicle center side end face;
• and
• rolling members provided between the two bearing tracks of said outer ring and said first and second bearing tracks,
• wherein said end portion of the hub is formed integrally with a first smaller diameter circumferential portion continuously to a portion of the second bearing track through a step portion therebetween, a circumferential diameter of the first smaller diameter circumferential portion is smaller than that of the second bearing track and said inner ring element being fitted on the first smaller diameter circumferential portion;
• in a state before plastically deformed by caulking, said end portion of the hub being further formed with a second smaller diameter peripheral portion that is continuous to the first smaller diameter circumferential portion and has a smaller diameter than that of the first smaller diameter circumferential portion, and
• the start point of the second smaller diameter circumferential portion is located at a position whose distance from said step portion of the hub is smaller than the width of the inner ring element and larger than the length of difference between the width of the inner ring element and the length from the start point of the inner surface of the chamfered portion to said vehicle center side end face of the inner ring element.

A hub unit for wheel comprising:

• an outer ring having two bearing tracks on its inner circumferential surface;
• a hub having a wheel mount flange on the outer end side and an end portion on the axially vehicle center side, said hub having, as a separate part or integrally on its outer circumference, a first bearing track corresponding to the axially vehicle outer end side bearing track of said outer ring;
• an inner ring element fitted on said end portion side of said hub, said inner ring element having on its outer circumference a second bearing track opposed to the axially vehicle center side bearing track of said outer ring and being fixed on said end portion by plastically deforming said end portion of said hub radially outwardly by caulking;
• and
• rolling members provided between the two bearing tracks of said outer ring and said first and second bearing tracks,
• wherein a continuous circumferential groove is provided on the inner circumferential surface of said inner ring element at an axially more vehicle center side than the second bearing track;
• and
• a portion of the hub end portion on which the inner ring element is fitted, is expanded inside the continuous circumferential groove of said inner ring element by material forming the hub end portion having been flown and expanding therein.