JPH0439455Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention relates to a hydrodynamic bearing device that supports a shaft using the dynamic pressure of a fluid.

<Prior Art> Conventionally, there has been a hydrodynamic bearing device as shown in FIG. In FIG. 4, reference numeral 1 denotes a fixed shaft having a groove 7 for generating dynamic pressure on its outer peripheral surface, and an inner magnet 5 is fixed to its end surface 1a. An outer magnet 6 is arranged on the inner surface 3a of the cover part 3, which constitutes a part of the housing 2 that houses the end surface 1a of the fixed shaft 1 and covers the inner magnet 5, with the same polarity facing the inner magnet 5. are mated. Therefore,
The shaft 1 is supported relatively in the thrust direction by the repulsive force between the outer magnet 6 and the inner magnet 5, and the pumping action of the shaft 7 generated by the relative rotation of the fixed shaft 1 with respect to the housing 2. Therefore, the shaft 1 is supported in the radial direction. Also, gap 9
is set to be sufficiently small compared to the distance between the inner magnet 5 and the outer magnet 6 in the space 8.
It functions as a throttle passage that communicates with the outside (hereinafter, the above-mentioned gap 9 will be referred to as a throttle passage). Therefore, the fluid in the space 8 is in an incompletely sealed state.

In this hydrodynamic bearing device, when a force that displaces the shaft 1 relative to the housing 2 is generated due to vibration or a shocking disturbance, the bearing device is sealed by the cover portion 3 and closed by the throttle passage 9. Due to the damper effect of the fluid in the space 8 that communicates with the outside,
Vibrations are quickly absorbed.

<Problems to be solved by the invention> However, the conventional hydrodynamic bearing device described above includes a cover part 3 that seals the fluid between the inner magnet 5 and the outer magnet 6, and the cover part 3 seals the fluid between the inner magnet 5 and the outer magnet 6. It includes a throttle passage 9 that communicates the space 8 with the outside,
Due to the damper effect of the fluid sealed in the space 8, the force that displaces the shaft 1 relative to the housing 2 is quickly absorbed. vibration,
Alternatively, while it has the advantage of being able to quickly attenuate large amplitude vibrations caused by shocking disturbances, it is difficult for the air sealed in the housing 2 by the shaft 1 to escape during assembly, and the shaft There is a problem that it takes time to insert 1.

Therefore, in order to deal with the above-mentioned problems, it is conceivable to simply provide holes in the housing 2 to allow the fluid to escape. However, in this case, if grease is used as the fluid for generating dynamic pressure, the centrifugal force during driving will scatter the grease to the outside from the hole.

Therefore, the purpose of this invention is to provide a passage that allows the air inside the cover to quickly flow out to the outside during assembly, while also preventing the fluid inside the cover from flowing out during drive. Our objective is to provide a hydrodynamic bearing device that can be inserted into your home and is easy to assemble.

<Means for Solving the Problems> In order to solve the above object, this invention stores a part of the shaft in a housing and provides a groove on at least one of the inner circumferential surface of the housing or the outer circumferential surface of the shaft. The rotation of the housing generates dynamic pressure in the fluid between the shaft and the housing to support the shaft in the radial direction, and furthermore, a force is applied in the thrust direction between the end surface of the shaft and the end surface of the housing. In a hydrodynamic bearing device, a hydrodynamic bearing device is provided with a cover portion that supports a shaft in the thrust direction by generating a thrust and seals fluid between an end surface of the shaft and an end surface of the housing, the cover portion having an inner side and an outer side of the housing. The present invention is characterized in that a passage is provided which communicates with the housing, and the passage is oriented such that the fluid in the passage is drawn back into the housing by the centrifugal force accompanying the rotation of the housing.

<Operation> When the shaft is inserted into the housing during assembly, the air that would otherwise be sealed between the end face of the shaft and the end face of the housing (i.e., inside the cover part) is quickly pushed out to the outside through the passage. The shaft is inserted in a short time.

On the other hand, during driving, fluid that has entered the passage from within the cover portion is pulled back into the housing by centrifugal force accompanying rotation of the housing, and is prevented from flowing outside. Therefore, the effect of preventing the fluid within the cover portion from scattering can be obtained.

<Example> This invention will be explained in detail below with reference to the illustrated example.

In FIG. 1, 11 is a fixed shaft housed in a housing 12. As shown in FIG. A groove 17 for generating dynamic pressure is provided on the outer peripheral surface of the shaft 11. Therefore, fluid pressure is generated in the gap 19 between the outer peripheral surface of the shaft 11 and the inner peripheral surface of the housing 12 by the pumping action of the groove 17 caused by the relative rotation of the shaft 11 with respect to the housing 12. occurs. This fluid pressure supports the shaft 11 in the radial direction.

On the other hand, at least one of the inner surface 13a of the cover part 13 constituting a part of the housing 12 that accommodates the end surface 11a side of the shaft 11 or the end surface 11b of the protrusion provided on the end surface 11a of the shaft 11 is provided with a structure for generating dynamic pressure. A spiral groove (not shown) is provided. Therefore, fluid pressure is generated by the pumping action of the spiral groove due to the rotation of the shaft 11 relative to the housing 12. This fluid pressure supports the shaft 11 in the thrust direction.

In this manner, in this embodiment, the shaft 11 is supported in the radial and thrust directions by fluid pressure. At this time, in order to obtain a large fluid pressure, oil or grease is used as a fluid for generating dynamic pressure.

Further, the cover portion 13 is provided with a passage 21 that extends obliquely from the inside to the outside toward the center of the housing 12.

In the hydrodynamic bearing device having the above configuration, when the shaft 11 is inserted into the housing 12 during assembly, the gap between the outer circumferential surface of the shaft 11 and the inner circumferential surface of the housing 12 is small, so that the housing 12 and the cover part 1
3 and the shaft 11 are forced out through the passage 21. Therefore, the shaft 11 can be inserted into the housing 12 in a short time.

On the other hand, when the housing 12 rotates during driving, fluid such as oil or grease that has entered the passage 21 in an attempt to flow out is returned to the opening 21a inside the passage 21 by centrifugal force, and is returned to the inside of the housing 12. will be collected. Therefore, oil or grease is not scattered to the outside, and the long-term reliability of the bearing can be improved.

Further, in this embodiment, the interval between the gaps 19 is set to be sufficiently small. Therefore, fluid cannot flow out from the space 20 formed between the end surface 11a of the shaft 11 and the inner surface 13a of the cover part 13 and around the groove 17. Thus, axis 1
This prevents the fluid that generates fluid pressure between the bearing 1 and the housing 12 from decreasing, thereby preventing the reliability of the bearing from decreasing. In this way, during assembly, the air that is to be sealed in the housing 12, the inside of the cover section 13, and the shaft 11 is allowed to flow out through the passage 21;
1 prevents oil or grease in the passage 21 from scattering to the outside. Therefore, a hydrodynamic bearing device with long-term reliability can be easily assembled in a short period of time.

In another embodiment shown in FIG. 2, like the embodiment shown in FIG. 1, the shaft 11 is supported in the thrust direction and the radial direction by the fluid pressure of a fluid such as oil or grease. A passage 32 is provided from the side surface 31a of the protrusion 31 provided on the inner surface 13a of the cover part 13 toward the rotation center of the cover part 13, and a passage 33 is provided at the rotation center of the cover part 13 to communicate the passage 32 to the outside.

In this hydrodynamic bearing device, when the shaft 11 is inserted into the housing 12 during assembly, the housing 12
2. The air that is about to be sealed in the cover part 13 and the shaft 11 is pushed out through the passages 32 and 33, allowing the shaft 11 to be inserted into the housing in a short time. On the other hand, during driving, oil or grease that has entered the passage 32 is collected into the housing 12 by centrifugal force and is not scattered to the outside.

In another embodiment shown in FIG. 3, the passage 33 of the embodiment shown in FIG. . Therefore,
The oil or grease that has entered the passage 41 is sent toward the passage 32 as the housing 12 rotates due to the reverse threaded structure of the passage 41. and,
Furthermore, the centrifugal force caused by the rotation of the passage 32 prevents the particles from being collected in the housing 12 and scattered to the outside.

<Effect of the invention> As is clear from the above, this invention supports the shaft in the radial direction using the fluid pressure generated between the shaft and the housing, while at the same time supporting the shaft in the radial direction using the fluid pressure generated between the shaft and the housing. In devices that generate force in the thrust direction and support the shaft in the thrust direction,
A cover part seals the fluid between the end face of the shaft and the end face of the housing, and a passageway is provided that allows the air inside the cover part to flow out to the outside during assembly, but prevents it from flowing out during drive. When the shaft is inserted into the housing, the air within the cover portion can be quickly discharged to the outside through the passage, so that the shaft can be inserted into the housing in a short time and easily assembled.

Furthermore, during driving, the passage can prevent the fluid within the cover portion from flowing out using centrifugal force, thereby preventing the fluid within the cover portion from scattering.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of a hydrodynamic bearing device that is an embodiment of this invention, Figs. 2 and 3 are partial sectional views of embodiments different from Fig. 1, and Fig. 4 is a conventional hydrodynamic bearing device. FIG. 11... Shaft, 12... Housing, 13... Cover portion, 21, 32, 33, 41... Passage, 17
... Radial dynamic pressure generation groove, 19 ... Throttle passage,
20... Sealed space.

Claims (1)

[Claims for Utility Model Registration] A part of the shaft is housed in the housing, and a groove is provided on at least one of the inner circumferential surface of the housing or the outer circumferential surface of the shaft, so that rotation of the housing can cause a gap between the shaft and the housing. Dynamic pressure is generated in the fluid to support the shaft in the radial direction, and
A cover part is provided that supports the shaft in the thrust direction by generating a force in the thrust direction between the end face of the shaft and the end face of the housing, and also seals the fluid between the end face of the shaft and the end face of the housing. In the hydrodynamic bearing device, a passage is provided in the cover portion to communicate the inside and outside of the housing, and the direction of the passage is such that the fluid in the passage is drawn back into the housing by centrifugal force accompanying rotation of the housing. A hydrodynamic bearing device characterized in that it is oriented in such a way that the