JPH0242616A - Dynamic pressure bearing device - Google Patents

Abstract

PURPOSE:To make the diameter of a cylinder outer diameter small by making a rotary transformer into a plane faced type and arranging a driving motor in a plane faced type outside the axial direction of the cylinder. CONSTITUTION:A rotary side rotary transformer 22a and a fixed side rotary transformer 22b are fitted to the axial direction faced surfaces of a rotary cylinder 20 and a fixed cylinder 10, respectively, they composed the plane faced type rotary transformer, and a rotor magnet 24a is fitted to a part extended in the axial direction at a side opposite to the fixed cylinder 10 of the rotary cylinder 20. A stator coil 24b arranged between the rotor magnet 24a and rotary cylinder 20 and faced to the rotor magnet 24a in the axial direction is fitted to a substrate 25 having an insertable notch part 26 around the rotary cylinder 20 in a radius direction and composes the plane faced type driving motor. Thus, the cylinder outer diameter can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydrodynamic bearing device used in a magnetic head cylinder of audio/visual equipment, information computer equipment, etc.

[Conventional technology]

Conventionally, this type of dynamic pressure bearing device for a magnetic head cylinder is
For example, it has a structure as shown in FIG.

The lower end of the fixed shaft 2 is fixed to the fixed cylinder 1, and the fixed shaft 2
A cylinder body 3b to which a magnetic head 4 is attached is integrally coupled to a sleeve 3a rotatably fitted around the cylinder body 3a, and the sleeve 3a and cylinder body 3b constitute a rotating cylinder 3.

The sleeve 3a of the rotating cylinder 3 is a dynamic pressure type constructed between the outer circumferential surface of the fixed shaft 2 and the inner circumferential surface of the sleeve 3a, in which grooves 5a and 5b for generating herringbone-like dynamic pressure are provided. The sleeve 3a is radially supported by a radial fluid bearing.
It is supported in the axial direction by a pivot-type dynamic pressure type thrust fluid bearing constructed between a thrust receiver 6 fixed to the upper end and the upper end surface of the fixed shaft 2.

A cylindrical fixed rotary transformer 7a arranged radially outside the sleeve 3a is attached to the fixed cylinder 1, and a cylindrical rotary transformer 7b radially opposed to the fixed rotary transformer 7a is attached to the sleeve 3a. These rotary transformers 7a and 7b constitute a circumferentially opposed rotary transformer.

Further, an annular stator coil 8a disposed on the radially outer side of the rotary transformer is attached to the fixed cylinder 1, and an annular rotor magnet 8b axially opposed to the stake coil 8a is attached to the sleeve 3a.
These stator coil 8a and rotor magnet 8b constitute a planarly opposed drive motor.

[Problem to be solved by the invention]

The hydrodynamic bearing device used in the conventional magnetic spatula 1' cylinder consists of a fixed cylinder 1 and a rotating cylinder 3 as described above.
A magnetic head 4° rotary transformer is installed in the internal space between the! The fixed side rotary transformer 7a and the rotating side rotary transformer 7b, which constitute the JI, and the stator coil 8a and rotor magneto 8b which constitute the drive motor are accommodated.

However, in recent years, there has been a strong demand for smaller magnetic head cylinders with smaller cylinder outer diameters.For example, in addition to the normal cylinder outer diameter of 62 fins, there is a demand for smaller cylinder outer diameters of 15 mm or less. It's coming out.

However, it is difficult to accommodate all of the components of the magnetic head, rotary transformer, and drive motor inside the conventional hydrodynamic bearing device, which has a reduced diameter as described above, for the following reasons. There is a limit to this, and the practical application of products below a certain limit is prevented.

In other words, when the diameter of a rotary transformer housed in a conventional hydrodynamic bearing device is the same, it becomes difficult to wind the coil, making mass production difficult and increasing costs. However, if the diameter of the rotor magnet of the drive motor is reduced, there is a problem that it becomes impossible to secure the torque necessary to drive the device.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a hydrodynamic bearing device in which the outer diameter of the cylinder can be reduced without being restricted by the machining of the rotary transformer or the torque of the drive motor.

[Means to solve the problem]

In this invention, in order to achieve the above object, the rotary transformer on the rotating side and the rotary transformer on the fixed side are respectively attached to the axially opposing surfaces of the rotating cylinder and the fixed cylinder to form a planar facing type rotary transformer. The rotor magnet is attached to a portion of the rotating cylinder that extends in the axial direction on the opposite side from the fixed cylinder, and the stator coil is disposed between the rotor magnet and the rotating cylinder and faces the rotor magnet in the axial direction. In this example, a cutout portion that can be inserted around a rotating cylinder is attached to a substrate that extends in the radial direction, thereby forming a planar facing drive motor.

[Effect]

In the hydrodynamic bearing device of the present invention, since the rotary transformer on the rotating side and the rotary transformer on the stationary side that constitute the rotary transformer are of the type that face each other in a plane, even when the outer diameter of the cylinder is reduced, the bearing can be of the type that faces each other on the circumferential surface. The coil winding process is easier than that, and since the rotor magnet and stator coil that make up the drive motor are placed on the outside of the cylinder in the axial direction and face each other in a plane, there are no restrictions on the outside diameter of the cylinder. It is possible to increase the outer diameter of the rotor magnet without causing damage.

〔Example〕

An embodiment of the invention will be described based on FIG.

A sleeve 20a is rotatably fitted around a fixed shaft 11 whose lower end is fixed to a fixed cylinder lO.
The rotary cylinder 20 is constituted by the cylinder body 20b which is integrally connected to the lower half of the sleeve 20a in the axial direction. Sleeve 20a is made of copper alloy, cylinder body 2
0b is molded from aluminum alloy.

The outer peripheral surface of the fixed shaft 11 has herringbone-shaped grooves 12a for generating dynamic pressure at two locations separated in the axial direction.

12b is formed, and this radial bearing surface and a radial bearing surface formed on the inner diameter surface of the sleeve 20a opposite to this radial bearing surface support the sleeve 20a in the radial direction. bearings are configured.

A thrust receiver 13 made of a spherical body is press-fitted and fixed to the inner peripheral surface of the upper end of the sleeve 20a.
The convex spherical thrust bearing surface and the concave spherical thrust bearing surface formed on the upper end surface of the fixed shaft 11 opposite thereto constitute a pivot-shaped thrust bearing that supports the sleeve 20a in the axial direction. ing.

Further, a fixed shaft 1 is provided on the inner circumferential surface of the upper end of the sleeve 20a.
An air vent groove 14 is provided in the axial direction to communicate the space between the upper end of the thrust receiver 1 and the thrust receiver 13 with outside air.

A magnetic head 21 is attached to the lower surface of the outer circumferential side of the cylinder body 20b of the rotary cylinder 20, and an annular rotating side rotary is attached to the cylinder body 20b, which is arranged on the mounting surface of the lower surface of the magnetic head 21. A transformer 22a is attached.

An annular fixed-side rotary transformer 22b is attached to the mounting surface of the fixed cylinder 10 that faces the rotating-side rotary transformer 22a in the axial direction. It consists of a rotary transformer.

Further, an annular rotor magnet 24a is attached via a magnet case 27 to the upper end of the sleeve 20a extending axially upward from the cylinder body 20b.

The stator coil 24b, which is disposed between the rotor magnet 24a and the cylinder body 20b and faces the rotor magnet 24a in the axial direction, is a substrate fixed to a mounting member 12 provided on the outer peripheral side of the fixed cylinder 10. 25, these rotor magnets 2
4a and the stator coil 24b constitute a planarly opposed drive motor outside the cylinder in the axial direction.

As shown in FIG. 2, the substrate 25 of the stator coil 24b is provided with a notch 26 in the radial direction that opens at the periphery of the disc-shaped body, and the width between the opposing surfaces of the notch 26 is It is larger than the outer diameter of the sleeve 20a.

As a result, even when the drive motor is disposed outside the cylinder in the axial direction of a hydrodynamic bearing device in which the sleeve rotates around a shaft with one end fixed, the rotary cylinder 20
After assembling the rotating body in which the rotary transformer 22a on the rotating side of the magnetic head 212 and the rotor magnet throat 24a are integrally coupled to the fixed shaft 11, the substrate 25 to which the stator coil 24b is attached is connected to the rotor magnet 24a and the cylinder body 20b. The rotor magnet 2
4a can be configured as a planarly opposed drive motor that exerts an attractive force toward the fixed cylinder main body.

FIG. 3 shows another embodiment of the invention.

In this embodiment, the sleeve 20a and the cylinder body 20b of the rotating cylinder 20 are integrally molded from the same material, and the magnetic head 21 and the rotating side rotary transformer 22a are integrally molded.
This means that the number of parts is reduced by using parts that have been joined together in advance.

In this way, the assembly work becomes easier than that shown in FIG.

The rotating cylinder 20 is made of aluminum alloy,
By using zinc alloy, magnesium alloy, etc., the weight of the entire device becomes lighter compared to the one shown in FIG.

The configuration other than the above is the same as in Figure 1, so
Identical parts are given the same reference numerals.

In the above embodiment, the spherical thrust receiver press-fitted into the sleeve and the fixed shaft make point contact to form a pivot-type thrust bearing. It can also be configured as a dynamic pressure type thrust fluid bearing in which the receiver and the upper end surface of the fixed shaft face each other in a plane.

Furthermore, in the above embodiment, the groove for generating dynamic pressure provided on the outer diameter surface of the fixed shaft may be provided on the inner diameter surface of the sleeve, or may be provided on both the outer diameter surface of the fixed shaft and the inner diameter surface of the sleeve. Good too.

〔Effect of the invention〕

As explained above, in the hydrodynamic bearing device of the present invention, the rotary transformer is of a plane-opposing type, so even if the outer diameter of the cylinder is reduced, winding can be easily performed, and mass productivity is not impaired. In addition, since the drive motor is of a planar opposed type and is placed outside the cylinder in the axial direction, the outer diameter of the rotor magnet is not restricted by the outer diameter of the cylinder, and the size necessary to secure torque can be used. This makes it possible to reduce the outer diameter of the cylinder.

Further, according to the present invention, since the notch is provided in the substrate of the stator coil of the drive motor, the fixed cylinder, rotating cylinder, stator coil, and rotor magnet can be arranged in the axial direction in the order of the shaft. It becomes possible to assemble a planarly opposed rotary transformer and a drive motor to a dynamic pressure bearing device of which one end is fixed and the sleeve rotates.

Further, according to the present invention, when the assembled hydrodynamic bearing device is transported, the base plate of the stator coil can prevent the rotary cylinder from being pulled out in the axial direction.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view showing an embodiment of the present invention, FIG. 2 is a plan view showing a stator coil substrate, FIG. 3 is a longitudinal side view showing another embodiment of the invention, and FIG. 4 is a conventional FIG. 3 is a vertical side view showing the hydrodynamic bearing device of FIG. In the figure, 10 is a fixed cylinder, 11 is a fixed shaft, 12a, 1
2b is a groove for generating dynamic pressure, 13 is a thrust receiver, 20 is a rotating cylinder, 20a and 20b are sleeves and cylinder bodies, 21 is a magnetic throat, 22a and 22b are a rotary transformer on the rotating side and a rotary transformer on the fixed side, respectively. , 24a and 24b are a rotor magnet and a stator coil, 25 is a substrate, and 26 is a notch. 2゜Figure 1

Claims (1)

[Claims] (1) A fixed cylinder to which one end of a fixed shaft is fixed; a fixed cylinder fitted around the fixed shaft, supported in the radial direction by a hydrodynamic radial bearing, and supported in the axial direction by a thrust bearing; a rotating cylinder that rotates in opposite directions; a magnetic head attached to the rotating cylinder;
A rotary side rotary transformer and a fixed side rotary transformer are attached to the rotating cylinder and the fixed cylinder, respectively, to constitute a rotary transformer, and a rotor magnet and a stator coil are attached to the rotating cylinder and the fixed cylinder, respectively, to constitute a drive motor. In the hydrodynamic bearing device, the rotating-side rotary transformer and the stationary-side rotary transformer are configured as planar-opposed rotary transformers attached to axially opposing surfaces of the rotating cylinder and the stationary cylinder, respectively, and the rotor magnet is configured such that: The stator coil, which is attached to the axially extending part of the rotating cylinder on the opposite side of the fixed cylinder and is disposed between the rotor magnet and the rotating cylinder and faces the rotor magnet in the axial direction, is inserted around the rotating cylinder. 1. A hydrodynamic bearing device, characterized in that it is configured as a planar drive motor mounted on a substrate provided with a radial cutout.