JP2001119913A - Self-cooled hydrodynamic pressure bearing brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-performance high-speed hydrodynamic pressure bearing brushless motor which suppresses heat generation, and is hardly influenced by temperature. SOLUTION: By forming cooling fins on a rotor yoke and forming holes in a circuit board, outside air is taken in from a rotor. The outside air forcedly taken along a sleeve having a dynamic pressure generating groove inside is led, and temperature increase of the surface of the sleeve having a bearing and heat generation of inside oil as well are suppressed. Air flow from the rotor to the circuit board is established from the holes of the board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention P. The present invention relates to a structure of a dynamic pressure fluid bearing brushless motor used for OA equipment such as C and a printer.

[0002]

2. Description of the Related Art In recent years, P.I. P. OA devices such as C tend to have high functions, high accuracy, and high speed in response to user needs, and low-cost products are demanded. Under such market trends, there is a demand for a high-performance, high-precision, high-speed, and inexpensive hydrodynamic fluid bearing brushless motor used for driving the functions of various parts of the OA equipment. .

As shown in FIG. 1, in a brushless motor of a hydrodynamic bearing, a magnetic field is generated by an electromagnetic action in a core 5 provided with a winding. Repulsion and attraction work between this magnetic field and the magnetic field of the magnet 9 disposed opposite the core 5, and the rotor yoke 3 holding the magnet rotates integrally with the rotating shaft 1.

A dynamic pressure fluid bearing (sleeve) 7 for bearing the rotary shaft 1 in the axial direction is disposed on the rotary shaft 1, and a dynamic pressure is generated on either the rotary shaft 1 or the sleeve 7. A groove is provided. The rotating shaft 1 integrated with the rotor yoke 3 is held in the sleeve 7 via the lubricating fluid by the dynamic pressure generated during rotation by the sleeve 7, the rotating shaft 1 and the lubricating fluid interposed therebetween. During the rotation, the holding force (dynamic pressure) increases as the number of rotations increases. In addition, increasing the number of revolutions with an increase in speed requires increasing the holding force. It generates heat inside the sleeve,
This leads to an increase in the temperature of the interposed lubricating fluid. With this, the temperature rise of each component existing inside the rotor is also led, and the characteristics of the brushless motor of the hydrodynamic bearing are reduced.

[0005]

The holding force generates heat inside the sleeve due to the shearing force of the oil due to the rotation and the frictional force due to the viscosity of the oil, leading to an increase in the temperature of the intervening oil. Along with this, the holding force is reduced, and the temperature rise of the parts inside the rotor due to the temperature rise of the sleeve itself provided with the dynamic pressure generating groove is also led, and the characteristics of the motor as a dynamic pressure fluid bearing brushless motor Is reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-performance, high-speed hydrodynamic bearing brushless motor that suppresses heat generation, is less affected by temperature, and has high performance.

[0007]

A cooling fin is provided on a rotor yoke and a hole is provided in a circuit board to take in outside air from a rotor and forcibly take it in along a sleeve having a dynamic pressure generating groove therein. It can guide outside air, suppress the temperature rise on the surface of the sleeve having the bearing, and also suppress the heat generation of the oil inside. Create a flow of air from the rotor to the board through the holes in the circuit board.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the heat sources of a hydrodynamic fluid bearing brushless motor
The lubricating fluid for generating dynamic pressure in the dynamic pressure generating groove inside the sleeve 7 is provided on the cooling fin 2 formed on the upper surface of the sheet metal rotor yoke 3 by press working and the cooling fin 2. The outside air outside the motor is taken in by the hole 10. The dynamic pressure generating groove may be formed on either the bearing surface of the sleeve or the outer peripheral surface of the rotating shaft.

The outside air taken in from the holes 10 is cooled by the cooling fins 2.
Accordingly, the temperature rise of the surface of the sleeve 7 is suppressed and the heat generation of the lubricating fluid interposed in the hydrodynamic bearing (groove) 6 is suppressed.

The outside air guided to the surface of the sleeve 7 is discharged to the outside of the motor through a hole 8 provided in the circuit board 4 near the attachment of the sleeve 7 to secure an air flow path.
The shape of the cooling fin 2 is formed on the upper surface of the sheet metal rotor yoke 3.
A vertical plane is provided at an angle of 45 degrees with respect to the center of the rotor, and a hole 10 for taking in outside air is arranged on the plane. From the upper part of the vertical surface to the next vertical surface, a blade is formed in the direction opposite to the rotation direction, the upper part of the vertical surface is horizontal, and the next vertical surface is at an angle of 45 degrees from the circle inside the fin forming part They are connected by an appropriate R-plane shape.

[0011]

The cooling fins and the holes provided in the fin portions take in outside air at a temperature lower than the inside of the motor, thereby suppressing the outer peripheral surface of the sleeve and the temperature rise of the lubricating fluid for generating dynamic pressure. As a result, it is possible to suppress the deterioration of the lubricating fluid due to the temperature rise and the accompanying decrease in the motor characteristics.

Since the cooling fin is formed integrally with the rotor, which is a rotating body, the efficiency of suppressing the temperature rise is proportional to the number of rotations. Also, since the cooling fins are formed simultaneously by pressing when forming the rotor yoke, the number of components does not increase, so that the function can be increased at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a motor according to an embodiment of the present invention.

FIG. 2 is a sectional view, a plan view, and a perspective view of a rotor yoke.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Cooling fin 3 Rotor yoke 4 Circuit board 5 Core 6 Dynamic pressure generating groove 7 Dynamic pressure fluid bearing (sleeve) 8 Hole 9 Magnet 10 Hole

Continuation of the front page (72) Inventor Hiromasa Masuda 2-4-19 Nakane, Meguro-ku, Tokyo F-term in Canon Seiki Co., Ltd. (reference) 3J011 AA09 BA02 BA10 CA02 5H019 CC04 DD01 EE14 FF01 FF03 5H607 AA02 BB01 BB09 BB14 CC01 DD01 DD02 GG01 GG02 GG09 GG12 GG14 5H611 AA03 BB01 BB08 PP03 QQ04 5H621 GA01 GA04 HH01 JK01 JK07 JK11 JK13 JK14 JK19

Claims (4)

[Claims] A magnet, a rotor yoke and a shaft rotate integrally, and the rotating shaft has a hydrodynamic bearing so as to cover the rotating shaft in the axial direction, and the hydrodynamic bearing, the rotating shaft and lubrication interposed therebetween. In a dynamic pressure fluid bearing brushless motor in which a rotating shaft is held by dynamic pressure generated during rotation with a fluid, a cooling fin is provided on the upper surface of a rotor yoke in a direction opposite to a rotating direction, and a hole is provided in a rotating substrate. A self-cooling hydrodynamic bearing brushless motor characterized in that when the rotor rotates, the surface of the hydrodynamic bearing and the lubricating fluid therein are self-cooled and the temperature is suppressed. 2. A sleeve having a bearing surface therein, a core disposed radially outward of the sleeve, a rotating shaft rotatably bearing on the bearing surface of the sleeve, and a rotor yoke attached to the rotating shaft. A rotor comprising a magnet attached to the rotor yoke so as to generate an electromagnetic force together with the core; a dynamic pressure generating groove formed on either a bearing surface of the sleeve or an outer peripheral surface of the rotating shaft; A cooling fin formed on the rotor yoke, which is configured to introduce air from the outside of the rotor yoke into the inside of the rotor yoke where the sleeve is present when the rotor rotates, and a cooling fin formed on the rotor yoke. Fluid bearing brushless motor. 3. The self-cooling hydrodynamic bearing brushless motor according to claim 2, wherein said rotor yoke vertically hangs from a ring-shaped plate portion fixed horizontally to said rotary shaft and an outer peripheral edge of said plate portion. The cooling fin is formed at the center of the plate portion, the sleeve is supported on a circuit board, and the circuit board receives air introduced into the rotor yoke by the cooling fin. A self-cooling hydrodynamic bearing brushless motor, characterized in that a hole for discharging is formed. 4. The self-cooling hydrodynamic bearing brushless motor according to claim 1, wherein said cooling fin has a plurality of holes formed to introduce air when the rotor rotates. A plurality of vanes arranged obliquely so that air introduced through the holes is directed toward the outer periphery of the sleeve inside the rotor yoke. .