JPH0514630U - Dynamic bearing device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a dynamic pressure bearing device, to prevent partial contact between the sleeve and the shaft body. [Structure] Since the corners 3a, 3b of both ends of the shaft body 3 are crowned so that the diameter of both ends of the shaft body 3 in the axial direction is smaller than the diameter of the central part in the axial direction of the shaft body 3, both ends of the shaft body are Compared to the conventional example in which the corners of the parts are not crowned, the shaft 3
The gap between the corners 3a, 3b and the sleeve 5 becomes large. Therefore, when the center axis of the sleeve 5 is inclined with respect to the center axis of the shaft body 3 at the time of starting or overloading, the sleeve 5
It is possible to prevent partial contact between the shaft 3 and the corners 3a, 3b of the shaft 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a dynamic pressure bearing device including a rotor and a stator.

[0002]

[Prior Art]

 Conventionally, as this type of dynamic pressure bearing device, there is one shown in FIG. In this dynamic pressure bearing device, a shaft body 33 is connected to a shaft 2 fixed to a bottom plate 1, and the shaft body 33 is housed in a sleeve 5. A dogleg-shaped dynamic pressure groove 36 is provided on the outer peripheral surface of the shaft body 33 facing the sleeve 5. The stator 7 is attached to the outer peripheral surface of the shaft 2 facing the sleeve 5, and the rotor 8 facing the stator 7 is attached to the inner peripheral surface of the sleeve 5. A magnet 11 is attached to the upper plate portion 5a of the sleeve 5 via an attaching member 10. The magnet 12 is fixed to the shaft body 33 so that the same poles as the magnet 11 face each other.

In the above dynamic pressure bearing device, when the rotor 8 and the sleeve 5 are integrally rotated by the rotating magnetic field generated by the stator 7, the dynamic pressure groove 36 provided in the shaft body 33 is provided between the sleeve 5 and the shaft body 33. A dynamic pressure is generated in the air to support the sleeve 5 in the radial direction. The repulsive force of the magnets 11 and 12 supports the sleeve 5 in the axial direction.

[0004]

[Problems to be solved by the device]

 However, in the above conventional hydrodynamic bearing device, when the shaft body 33 and the sleeve 5 are misaligned, or at the time of start-up or overload, the central axis of the sleeve 5 is inclined with respect to the central axis of the shaft body 33. In this case, the corners 33a and 33b at the axial end of the shaft body 33 are easily unevenly contacted with the inner peripheral surface of the sleeve 5, and this uneven contact causes a torque required for starting and a torque required for overload rotation. There is a problem of increasing.

Therefore, an object of the present invention is to provide a dynamic bearing device capable of preventing partial contact between the sleeve and the corner portion of the shaft body.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a hydrodynamic bearing device of the present invention has a shaft connected to a shaft housed in a sleeve, and an outer peripheral surface of the shaft facing the sleeve or an inner circumference of the sleeve facing the shaft. A dynamic pressure groove is provided on at least one of the surfaces, and the rotor is attached to one of the outer peripheral surface of the shaft facing the sleeve and the inner peripheral surface of the sleeve facing the shaft, and the rotor is attached to the other. The opposite stators are attached, and the corners of both ends are curved so that the diameter of both ends of the shaft facing the inner peripheral surface of the sleeve in the axial direction is smaller than the diameter of the central part of the shaft in the axial direction. It is characterized by being allowed.

[0007]

[Action]

 Since the corners of both ends of the shaft are curved so that the diameter of both ends in the axial direction of the shaft is smaller than the diameter of the central part of the shaft in the axial direction, the corners are not curved. The gap between the corner of the shaft and the sleeve is larger than in the example. Therefore, when the center axis of the sleeve is inclined with respect to the center axis of the shaft body at the time of starting or overloading, partial contact between the sleeve and the corner portion of the shaft body is prevented.

[0008]

【Example】

 Hereinafter, the present invention will be described in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the dynamic pressure bearing device of the present invention. This embodiment differs from the conventional example only in that a shaft body 3 is provided in place of the shaft body 33 of the conventional dynamic pressure bearing device shown in FIG. Therefore, the same parts as those of the conventional example will be denoted by the same reference numerals, and the description thereof will be omitted.

The shaft body 3 of this embodiment has a dogleg-shaped dynamic pressure groove 6, and the diameter of both axial ends facing the inner peripheral surface of the sleeve 5 is the central portion in the axial direction of the shaft body 3. The corners 3a, 3b at both ends are crowned so as to be smaller than the diameter of the. Therefore, the gap between the corners 3a and 3b of the shaft 3 and the sleeve 5 becomes large. Therefore, even if the central axis of the sleeve 5 is tilted with respect to the central axis of the shaft body 3 at the time of overload or when the sleeve 5 is stationary, the corner portions of the sleeve 5 and the shaft body 3 are prevented. It is possible to prevent uneven contact with 3a and 3b. Therefore, according to this embodiment, the sleeve 5 can be smoothly started at low torque at the time of start-up, and the sleeve 5 can be smoothly rotated even at the time of overload.

Further, even if the shaft body 3 hits the sleeve 5 evenly, since the corner portions 3a and 3b are subjected to the crowning process, the surface pressure of the corner portions 3a and 3b is small and the shaft body 3 is Can rotate smoothly.

In this embodiment, while the stator 7 is attached to the shaft 2 and the rotor 8 is attached to the sleeve 5, the rotor is attached to the shaft 2 and the stator is attached to the sleeve 5 to rotate the shaft 2. You can

[0013]

[Effect of the device]

 As is apparent from the above description, in the dynamic pressure bearing device of the present invention, the diameter of both axial end portions of the shaft body facing the inner peripheral surface of the sleeve is smaller than the diameter of the axial center portion of the shaft body. As described above, since the corners of the both ends are curved, the gap between the corner of the shaft and the sleeve is larger than that in the conventional example in which the corners are not curved. Therefore, when the center axis of the sleeve is tilted with respect to the center axis of the shaft body at the time of starting or overloading, it is possible to prevent partial contact between the sleeve and the corner portion of the shaft body. Therefore, according to this invention, the torque required at the time of starting can be reduced and the rotation at the time of overload can be made smooth.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a dynamic pressure bearing device of the present invention.

FIG. 2 is a cross-sectional view of a conventional dynamic pressure bearing device.

[Explanation of symbols]

1 Bottom Plate 2 Shafts 3,33 Shafts 3a, 3b, 33a, 33b Corners 5 Sleeves 6,36 Dynamic Pressure Grooves 7 Stator 8 Rotor 10 Mounting Member 11,12 Magnet

Claims (1)

[Scope of utility model registration request] 1. A shaft body connected to a shaft is housed in a sleeve, and a dynamic pressure groove is provided on at least one of an outer peripheral surface of the shaft body facing the sleeve and an inner peripheral surface of the sleeve facing the shaft body. A rotor is attached to one of an outer peripheral surface of the shaft facing the sleeve and an inner peripheral surface of the sleeve facing the shaft, and a stator facing the rotor is attached to the other of the inner peripheral surface of the sleeve. Of the shaft body facing each other in such a manner that the diameters of both end portions in the axial direction of the shaft body are smaller than the diameter of the central portion in the axial direction of the shaft body, and the corner portions of the both end portions are curved. .