US 6,307,295 B1Granted

Spindle motor and complex bearing assembly for use with the spindle motor

AssigneeSumitomo Electric Industries, Ltd.

InventorsKaoru Murabe, Makoto Otsuki, Osamu Komura

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Abstract

A complex bearing assembly has a sleeve and a shaft inserted in the sleeve. The shaft is rotatably supported in the sleeve through radial and axial bearings, i.e., hydrodynamic bearing and magnetic bearing. In particular, the axial bearing includes first and second magnetic members or magnet rings. The first magnetic member is secured on the shaft in a coaxial fashion, but the second magnetic ring is secured on the sleeve in an eccentric fashion. This causes an eccentric bias that forces the rotating shaft to a certain radial direction, allowing the rotating shaft becomes to lose frictional contacts with the sleeve at lower rotational number. This in turn decreases wears of the sleeve and the shaft, increasing the durability of the bearing assembly.

Claims18

Dependent claims

A complex bearing assembly, comprising:

a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said, second member, and wherein one of said first and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly.

3 more elements

A complex bearing assembly, comprising:

a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said second member, and wherein one of said first and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly, wherein said axial bearing includes two pairs of said first and second magnetic members and said two pairs are provided at opposite ends of said one and the other cylindrical members.

3 more elements

A complex bearing assembly, comprising:

a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said second member, and wherein one of said first and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly, wherein said radial bearing meets a following relation:
δ/C≦1.0×10−4
wherein
δ:
a difference of radii of coaxially arranged minimum circumscribed and maximum inscribed circles for said closed loop, and
C:
a mean diameter of said coaxially arranged minimum circumscribed and maximum inscribed circles.

9 more elements

A complex bearing assembly, comprising:

a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said second member, and wherein one of said fist and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly, wherein said radial bearing meets a following relation:
δ/C≦7.0×10−5
wherein
δ:
a difference of radii of coaxially arranged minimum circumscribed and maximum inscribed circles for said closed loop, and
C:
a mean diameter of said coaxially arranged minimum circumscribed and maximum inscribed circles.

9 more elements

A complex

bearing assembly, comprising:
a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said second member, and wherein one of said first and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly, wherein said inner and outer are designed so that they define one or more enlarged gap portions, each of said enlarged gap portions extending about 40% or more of a longitudinal length of said opposed peripheries.

4 more elements

A spindle motor having a complex bearing assembly, comprising:

a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said second member, and wherein one of said first and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly.

3 more elements

A spindle motor having a complex bearing assembly, comprising:

a base member;
a first cylindrical member having a cylindrical outer periphery defined therein;
a second cylindrical member having a cylindrical inner periphery defined therein, said inner periphery having a greater diameter than that of said outer periphery of said first member, wherein said outer periphery of said first member is positioned in said inner periphery of said second member, and wherein one of said first and second cylindrical members is fixed to said base member so that the other of said first and second cylindrical members rotates relative to said one of said first and second cylindrical members;
a radial bearing formed by said opposed inner and outer peripheries for supporting said the other cylindrical member in a radial direction relative to said one fixed cylindrical member by means of a hydrodynamic force generated in a rotational movement of said the other rotatable cylindrical member relative to said one fixed cylindrical member between said opposing inner and outer peripheries;
and
an axial bearing having a first magnetic member secured on said the other rotatable cylindrical member and extended around a rotational axis of said bearing assembly and a second magnetic member secured on said one fixed cylindrical member and extended around said first magnetic member while leaving a space therebetween so that said first and second magnetic members cooperate to generate a magnetic force therebetween for supporting said the other rotatable member in an axial direction relative to said one fixed cylindrical member, wherein one of said first and second magnetic member is positioned in a coaxial fashion with said rotational axis of said bearing assembly and the other of said first and second magnetic member is positioned in an eccentric fashion with said rotational axis of said bearing assembly, wherein said spindle motor is designed so that, in a rotational movement of said the other rotatable cylindrical member, said the other rotatable cylindrical member looses frictional contacts with said one fixed cylindrical at the rotational number of 2,000 rpm.

3 more elements

Dependencies are inferred from the claim text.