JPS6044620A - Dynamic pressure bearing device - Google Patents

Abstract

PURPOSE:To obtain an inexpensive power bearing device having a long life without use of a specific bearing material and lubricating oil by providing plural inclined grooves in a shaft hole of bearing metal made of a porous sintered alloy, and impregnating grooves with oil and interposing grease therebetween. CONSTITUTION:Bearing metal 30 is made of a porous sintered alloy, including plural inclined grooves 30a provided in a shaft hole thereof 30. With rotation of the shaft 11, grease is pushed in between the shaft 11 and the shaft hole of the bearing metal 30 along the grooves 30a in the bearing metal 30, allowing a fluid film 31a to be formed between said shaft 11 and said shaft hole. Accordingly, the shaft 11 is rotated in a non-contact state with respect to the shaft hole. Porous portions of the bearing metal 30 are impregnated with sufficient oil, and grease 31 having the same kinematic viscosity as that of said oil is interposed between the shaft and the shaft hole. In addition, a filler is blended in the grease 31. Consequently, the filler does not enter said porous portions, and the grease 31 is maintained as the fluid film 31a. The grease is prevented from flowing out since it is circulated between a grease reservoir 30b and the bearing surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrodynamic bearing device in which a plurality of spiral grooves or the like are formed on a bearing sliding surface.

As a bearing device, a hydrodynamic group bearing is known in which a plurality of spiral or herringbone grooves are formed on the sliding surface of the sliding bearing. Such a dynamic pressure group bearing is a type of sliding bearing, and as it rotates, a working fluid such as oil is pushed into the bearing along a plurality of grooves provided on the sliding surface, and the working fluid is This system generates high pressure and receives a load from this fluid pressure.

As the groove shape provided on the sliding surface, for example, a spirally curved groove with a substantially rectangular cross section and an angle between the longitudinal direction of the groove on the sliding surface and the rotating direction of the bearing is always constant. Grooves are generally provided on the sliding surface of either the rotating shaft or the bearing.

During operation of such a dynamic pressure group bearing, two opposing sliding surfaces are separated from each other by a fluid film, and both sliding surfaces rotate relative to each other without contacting each other. Therefore, it has the advantage of generating almost no noise or vibration and having high dynamic rotation accuracy. However, since it has a structure in which grooves are provided on the sliding surface, it has the effect of providing better stability where axial runout is small compared to ordinary sliding bearings without grooves.

On the other hand, in such a dynamic pressure group bearing, since the original dynamic pressure action does not occur during startup, the two sliding surfaces are directly connected to each other.
They come into contact and wear occurs due to the friction between the two sliding surfaces. Then, as the starting and stopping are repeated, the wear increases and the rotational accuracy is adversely affected. Therefore, as a countermeasure to this problem, the bearing material is selected to be a familiar material such as gunmetal, or a special lubricant is selected. This may increase the cost of bearings.

In view of the above-mentioned points, an object of the present invention is to form a plurality of inclined grooves in the shaft hole of a bearing metal, to construct this bearing metal from a porous sintered alloy, and to form a porous portion of the sintered alloy. It is an object of the present invention to provide a long-life, low-friction hydrodynamic bearing device that is impregnated with oil and has a gas interposed therebetween, which does not require special bearing materials or lubricants.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows a capstan motor for a deck, which is an example of application of the hydrodynamic bearing device according to the embodiment of the present invention. , described below.

In Fig. 1, the can is the rotating shaft of the electric motor.

The stand shaft 11 is press-fitted into a rotor 12 that also serves as a flywheel with the required inertia, and a multi-pole magnetized annular rotor magnet is placed in a recess formed on the lower surface of the rotor 12. 13 is fixed.

The capstan shaft 11 is supported by a thrust receiver 15 fixed on the stator core 14 and supported by a support column 16.
．． A base plate 17 is fixed parallel to the stator core 14 at a predetermined interval by interposition of a base plate 16, and a base plate 18 is fixed parallel to the stator core 14 at a predetermined interval further above the base plate 17. The bearing holder 19 is inserted through the bearing holder 19.

At both ends of the bearing holder 19 are bearing metals 30, which will be described later.
30 is fitted, these bearing metal 30.30
The capster/shaft 11 is rotatably supported by. A capstan shaft 1 is mounted on the first stator core 14.
A plurality of drive coils 20 are arranged concentrically with rotor magnet 1 at a predetermined circumferential angle, and are opposed to each other with a predetermined gap between the upper surface of each coil 20 and the lower surface of rotor magnet 13.

Further, a rotor magnet 13 is placed on the stator core 14.
A position detection element (not shown) made of a Hall element or the like that detects the magnetic pole of the rotor magnet 13 is disposed at a position facing the rotor magnet 13, and the energization to the drive coil 20 is controlled based on this detection signal. The rotor magnet 13 and the rotor 12 rotate as a non-commutator motor, and the rotor 1
The capstan shaft 11 rotates together with the capstan shaft 2. A concave portion 12cL is also formed on the upper surface of the rotor 12, and internal teeth 22 in the shape of an internal gear are formed on the inner peripheral surface of the concave portion 12α.

Upper and lower yokes 23 and 24 of the frequency generator fixed to the lower end of the bearing holder 19 are located in the recessed portion 12CL. ．． A ring-shaped excitation magnet 25 is disposed on the inner periphery between the magnets 24, and a power generation coil 26 wound in a ring shape in the circumferential direction is disposed on the outer side thereof. On the outer periphery of one yoke 23 of the frequency generator, external teeth 23a are formed in the shape of a gear.
and the external teeth 23α are opposed to each other with an appropriate interval.

The it coil 26 detects a magnetic change between the internal teeth 22 and the external teeth 23α due to the rotation of the rotor 12, outputs a signal corresponding to the rotation speed of the rotor 12, and based on this detection signal, the drive coil 20 Low month 2 by controlling the energization to
is designed to rotate at a constant rotation speed.

A printed wiring board 27 is fixed to the lower surface of the stator core 14. The printed wiring board 27 includes a group of circuit elements (Fig. (not shown) are provided. Note that the reference numeral 28 in the figure is a pinch roller that is pressed against the capsutor/shaft 11 and driven to rotate, and the tape or the like is caused to run by the rotation of this pinch roller 2B.

Now, to describe the hydrodynamic bearing device according to the embodiment of the present invention, in FIG. 1, the bearing metal indicated by the reference numeral 3o is the hydrodynamic group bearing described at the beginning.

The bearing metal 30 is formed into a sleeve shape, and a plurality of inclined herringbone-shaped grooves 30cL are formed on the sliding surface around the shaft hole, as shown in FIG. Note that this groove may have a plurality of spiral shapes.

The bearing metal 30 is made of a porous sintered alloy, and the porous portion has a kinematic viscosity of, for example, 1000C.
It is impregnated with silicone oil equivalent to /s. Note that this oil impregnation is carried out, for example, by a vacuum impregnation method under high temperature.

The capstan shaft 11 is fitted into the shaft hole of the bearing metal 30 configured as described above, and the capstan shaft 11 and
As shown in Fig. 3, a silicone-based grease 31 of the same type and equivalent to the same kinematic viscosity of 1000 C/S as the above-mentioned oil is interposed between the shaft hole and the sliding surface. . A large chamfered grease reservoir portion 30b is formed at one end of the shaft hole of the bearing metal 30,
3101 parts of grease is stored in this part.

Note that the above-mentioned 0/8 represents the kinematic viscosity (Senna-Stokes), and 1000 C//S is an example used in an experiment, and is not necessarily limited to this example. The oil equivalent to 10000/8 that is impregnated into the bearing metal is made by adding additives such as oxidation and corrosion inhibitors to liquid base oil.

In addition, 1.000°/8 interposed between the shaft hole and the shaft.
Corresponding greases are semi-solids made by adding solid particle fillers to base oils. Note that oils and greases other than silicone-based oils may be used. In addition, in FIG. 1, the reference numeral 19 (L
The reference symbol is an air vent, which is provided to make the atmospheric pressure inside the bearing holder 19 the same as the outside atmospheric pressure.

Here, when the motor shown in FIG. 1 is stopped, the capstan shaft 11 is also stopped, and in this state,
A part of the outer periphery of the shaft 1 is in contact with the sliding surface of the shaft hole of the bearing metal 30.

At the initial stage when the motor starts from such a stopped state and the shaft 11 begins to rotate, the oil impregnated in the bearing metal 3° achieves a lubrication function between the shaft 11 and the bearing metal 30. Ru.

On the other hand, after the motor is started and the shaft 11 starts rotating, the shaft 11 is moved along the groove 3oα of the bearing metal 3o (see Fig. 2).
Grease is pushed between the shaft hole of the bearing metal 3o, and a fluid film 31cL is formed between the two by a type of pumping action as shown in FIG. 3. Due to the pressure of this fluid film, The shaft 11 is spaced apart from the shaft hole, and the shaft 11 rotates without contacting the shaft hole.

This kind of function is called dynamic pressure effect.

When the shaft 11 rotates without contacting the shaft hole, the porous portion of the bearing metal 3o made of a sintered alloy is sufficiently impregnated with oil, and the grease 31 of the same kinematic viscosity is applied between the shaft and the shaft hole. This grease 31 is interposed between
Since the filler is mixed in, the filler does not enter the porous portion, and therefore, the grease 31 does not penetrate into the fluid film 31.
It is maintained as α.

Although the fluid film 31α moves with the rotation of the shaft 11, a grease reservoir 30b is provided, and the grease circulates between this portion and the shaft hole surface, so that the grease does not flow out. Prevented.

On the other hand, when the motor is started, the shaft 11 is
When in contact with the shaft hole surface of 0, the oil in the bearing metal flows toward the shaft 11 due to friction, and this oil achieves a lubrication function between the bearing metal and the shaft 11. Then, the oil flowing toward the shaft 11 advances to both ends of the bearing metal 30 and returns from both ends into the porous portion of the bearing metal, thereby performing a kind of pumping action.

In FIG. 1, when the pinch roller 28 presses the shaft 11, the shaft 11 tends to deviate due to this pressure, but due to the dynamic pressure action and the pressure action of the fluid film 31α formed by the grease 31, the shaft 11 rotates while maintaining the center position.

In this way, the oil impregnated into the bearing metal made of porous sintered alloy is interposed between the shaft and the bearing metal, so that no dynamic pressure is generated and when the shaft starts rotating, the oil is impregnated into the bearing metal. The oil achieves the lubrication function, and after startup, a fluid film is formed by the grease, and the shaft 11 is supported in a non-contact state due to the dynamic pressure action of the oil, so the shaft and bearing metal are It becomes less prone to wear, and accordingly, the life of the bearing device can be extended.

Further, since only general oil or grease is used, no special bearing material or lubricant is required, and the bearing device can be made inexpensive. Furthermore, even if a directional force perpendicular to the axial direction is applied to the supported shaft, the amount of deviation of the shaft will be small due to the dynamic pressure effect accompanying the formation of a fluid film by the grease, and for some reason Even if the shaft comes into direct contact with the bearing metal, the lubrication function is achieved by the oil impregnated within the bearing metal, so there is no risk of the shaft's rotational function being impaired. It can also respond to load conditions.

As described above, according to the present invention, it is possible to provide a long-life, low-friction hydrodynamic bearing device that does not require special bearing materials or lubricants, can maintain good rotational accuracy, and has a long life.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a capstan motor for a deck, with the main part taken in cross section, and FIG. 2 is a sectional view of the bearing metal of the device according to the invention. ,
FIG. 3 is a cross-sectional view of the dynamic pressure bearing device of the same embodiment. ll shaft, 30 bearing metal, 30a groove, 31 grease, 31a/fluid film.

Claims (1)

[Claims] A hydrodynamic bearing in which a plurality of inclined grooves are formed in a shaft hole of a bearing metal into which a shaft is rotatably inserted, and lubricating oil is interposed between the shaft and the shaft hole including the grooves. The bearing metal is made of a porous sintered alloy, and the porous portions of the sintered alloy are impregnated with oil, and
A dynamic pressure bearing device characterized in that a fluid film is formed between the shaft and the shaft hole by interposing grease of the same type and the same dynamic viscosity as the oil as a lubricating oil.