JPH0573317U - Hydrodynamic bearing - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a dynamic pressure bearing that can be used not only vertically but also horizontally. In a dynamic pressure bearing in which a part of the shaft 2 is housed in the bottomed sleeve 1, a space S between the bottomed sleeve 1 and the shaft 2 is formed when the bottomed sleeve 1 rotates in the direction of arrow A. The dynamic pressure grooves 3, 4, 5, 6 are formed on the outer peripheral surface of the shaft 2 so as to have a negative pressure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a dynamic pressure bearing that is used in, for example, a laser printer or a polygon mirror and that supports a shaft by the dynamic pressure of fluid.

[0002]

[Prior Art]

 Conventionally, there is a dynamic pressure bearing shown in FIG. In this dynamic pressure bearing, a part of a shaft 32 is housed in a bottomed sleeve 31. Dynamic pressure grooves 33, 34 are provided on the outer peripheral surface of the shaft 32. The dynamic pressure groove 33 pumps air as a lubricating fluid between the bottomed sleeve 31 and the shaft 32 to the opening 31a side of the bottomed sleeve 31, and the dynamic pressure groove 34 transfers the air to the bottomed sleeve. It is pumped to the bottom 31b side of 31. The axial length of the dynamic pressure groove 33 and the axial length of the dynamic pressure groove 34 are equal.

Further, a permanent magnet 35 is fixed to the axial end surface of the shaft 32 facing the bottom portion 31b of the bottomed sleeve 31, and the bottomed sleeve 31 is arranged so that the same pole faces the permanent magnet 35. A permanent magnet 36 is fixed to the bottom portion 31b of the. A bottom hole 31b of the sleeve 31 and a through hole 37 that axially penetrates the permanent magnet 36 are formed.

When the bottomed sleeve 31 of the dynamic pressure bearing and the shaft 32 rotate relative to each other, the dynamic pressure groove 33 and the dynamic pressure groove 34 generate a dynamic pressure in the air between the shaft 32 and the bottomed sleeve 31. Thus, the bottomed sleeve 31 is supported in the radial direction with respect to the shaft 32. Further, the bottomed sleeve 31 is axially supported by the shaft 32 by the repulsive force of the permanent magnets 35 and 36. Further, the through hole 37 penetrating the bottom portion 31b of the bottomed sleeve 31 and the permanent magnet 36 causes the axial vibration of the bottomed sleeve 31 with respect to the shaft 32 due to the ventilation resistance of the air passing through the through hole 37. It serves to dampen.

[0005]

[Problems to be solved by the device]

 However, in order to prevent the sleeve 31 from slipping out of the shaft 32, the conventional hydrodynamic bearing is limited in its use to the vertically arranged type in which the opening 31a of the sleeve 31 faces the direction of gravity, and the horizontally arranged type. There is a problem that it cannot be used and its application range is narrow.

Therefore, an object of the present invention is to provide a dynamic pressure bearing that can be used not only vertically but also horizontally and has a wide range of application.

[0007]

[Means for Solving the Problems]

 To achieve the above object, according to the present invention, a bottomed sleeve accommodates a part of a shaft, and a dynamic pressure groove is formed on at least one of an inner peripheral surface of the bottomed sleeve and an outer peripheral surface of the shaft. In the pressure bearing, the dynamic pressure groove is formed so that the space between the shaft and the bottomed sleeve has a negative pressure when the bottomed sleeve and the shaft rotate relative to each other. There is.

[0008]

[Action]

 When the bottomed sleeve and the shaft rotate relative to each other, the dynamic pressure generated by the dynamic pressure groove causes a negative pressure in the space between the shaft and the bottomed sleeve. Attracted towards the shaft. Therefore, according to the present invention, not only is the bottomed sleeve opening vertically oriented in the direction of gravity, but the bottomed sleeve opening horizontally oriented in the direction perpendicular to the direction of gravity. Also in use, there is no risk of the bottomed sleeve coming out of the shaft, and a dynamic pressure bearing that can be used not only vertically but horizontally is realized.

[0009]

【Example】

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

In the dynamic pressure bearing of this embodiment, as shown in FIG. 1, a part of the shaft 2 is housed in the bottomed sleeve 1. On the outer peripheral surface of the shaft 2, there are dynamic pressure grooves 3 and 5 for sending air between the bottomed sleeve 1 and the shaft 2 to the opening 1a side of the bottomed sleeve 1 and the air. Dynamic pressure generating grooves 4 and 6 are formed for pressure feeding to the bottom portion 1b side of the bottom sleeve 1. The axial dimension of the dynamic pressure groove 5 and the axial dimension of the dynamic pressure groove 6 are made equal, and the axial dimension of the dynamic pressure groove 3 is made larger than the axial dimension of the dynamic pressure groove 4. I'm listening.

Further, the permanent magnet 8 is fixed to the shaft end portion 2a of the shaft 2 facing the bottom portion 1b of the bottomed sleeve 1, and the bottomed sleeve is arranged so that the same pole as the permanent magnet 8 faces. A permanent magnet 7 is fixed to the bottom portion 1b of 1. The repulsive force of the permanent magnets 8 and 7 supports the sleeve 1 in the axial direction with respect to the shaft 2.

When the bottomed sleeve 1 rotates in the direction of arrow A, the dynamic pressure grooves 3, 4, 5, 6 generate a dynamic pressure in the air between the bottomed sleeve 1 and the shaft 2, and the shaft 2, the bottomed sleeve 1 is supported in the radial direction. Further, since the axial dimension of the dynamic pressure groove 3 is made larger than the axial dimension of the dynamic pressure groove 4, the air between the sleeve 1 and the shaft 2 flows toward the opening 1a of the sleeve 1. The space between the sleeve 1 and the shaft 2 (especially the space S between the bottom portion 1b of the sleeve 1 and the shaft end surface 2a of the shaft 2) becomes negative pressure. Therefore, the bottomed sleeve 1 is attracted to the shaft 2.

Therefore, according to the present embodiment, not only is the opening 1a of the bottomed sleeve 1 of the dynamic pressure bearing used in a vertical arrangement in which the direction of gravity is applied, but also the opening 1a is perpendicular to the direction of gravity. There is no risk of the bottomed sleeve 1 slipping out of the shaft 2 even in the horizontally oriented use, and it is possible to realize a dynamic pressure bearing that can be used not only vertically but also horizontally. Further, when the negative pressure in the space S is large enough to pull up the bottomed sleeve 1, it is also possible to use a reverse vertical arrangement in which the opening 1a of the bottomed sleeve 1 faces the direction opposite to gravity. Become.

In the above embodiment, the permanent magnets 7 and 8 are used to axially support the bottomed sleeve 1 with respect to the shaft 2. However, as shown in FIG. The shaft end 2a may be formed into a hemispherical shape, and the bottomed sleeve 1 may be pivotally supported by the hemispherical shaft end 2a. The dynamic pressure groove formed on the shaft 2 is not limited to the pattern shown in FIG. 2, but the air between the bottomed sleeve 1 and the shaft 2 can be closed as shown in FIG. 2B. It may be configured only by the dynamic pressure groove 10 that is pressure-fed to the opening portion 1a side, or, as shown in FIG. 2C, a dynamic pressure groove having a pattern similar to the pattern shown in FIG. 1 may be configured. .. Further, the dynamic pressure groove may be formed on the inner peripheral surface of the bottomed sleeve 1. The point is that the dynamic pressure groove may be formed so that the space between the bottomed sleeve 1 and the shaft 2 has a negative pressure.

[0015]

[Effect of the device]

 As is clear from the above description, the dynamic pressure bearing of the present invention has the dynamic pressure groove formed so that the space between the shaft and the bottomed sleeve has negative pressure.

Therefore, when the bottomed sleeve and the shaft rotate relative to each other, the dynamic pressure generated by the dynamic pressure groove causes a negative pressure in the space between the shaft and the bottomed sleeve. The bottom sleeve is pulled towards the shaft.

Therefore, according to the present invention, the opening of the bottomed sleeve is not only used vertically, but also the opening of the bottomed sleeve is oriented in the direction perpendicular to the direction of gravity. Even when used horizontally, there is no risk of the bottomed sleeve coming out of the shaft, and it is possible to realize a dynamic pressure bearing that can be used not only vertically but also horizontally, and it is possible to provide a dynamic bearing with a wide range of applications.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a modification of the above embodiment.

FIG. 3 is a cross-sectional view of a conventional dynamic pressure bearing.

[Explanation of symbols]

1 Bottomed sleeve 1a Opening 1b Bottom 2 Shaft 2a Shaft end 3, 4, 5, 6,
10 Dynamic pressure groove 7,8 Permanent magnet S Space

Claims (1)

[Scope of utility model registration request] 1. A dynamic pressure bearing in which a part of a shaft is housed in a bottomed sleeve, and a dynamic pressure groove is formed on at least one of an inner peripheral surface of the bottomed sleeve and an outer peripheral surface of the shaft. The dynamic pressure bearing is characterized in that the dynamic pressure groove is formed so that the space between the shaft and the bottomed sleeve has a negative pressure when the sleeve and the shaft rotate relative to each other.