JPH089587A - Electric motor - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide an electric motor using a hydrodynamic bearing having excellent reliability by eliminating oil shortage due to contact between a ring and a sleeve to form a very narrow gap. [Structure] A sleeve 26 and a rotary shaft 28 supported by radial bearings 34a, 34b composed of oil 33 and dynamic pressure generating grooves 32a, 32b formed on the inner peripheral surface thereof,
Magnet 29 and sleeve 26 fixed to rotating shaft 28
A ring 30 is arranged between the two to prevent them from coming into direct contact with each other, and a counterbore is provided on a contact surface 30a of the ring 30 with the sleeve 26. Therefore, the ring 3
0 and the sleeve 26 are in contact with each other, the oil 33 on the inner peripheral portion thereof
Prevents the oil 33 from escaping into the gap between the ring 30 and the sleeve 26 due to the capillary phenomenon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor having a hydrodynamic bearing.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view of a conventional electric motor, and FIGS. 9 and 10 are sectional views of a radial bearing portion of the same electric motor. As will be described below, this electric motor has a hydrodynamic bearing. In FIGS. 8, 9, and 10, reference numerals 1 and 2 denote frames, and a stator 4 having a coil 3 wound therein.
A substrate 5 equipped with a hall element or the like is installed in. The stator 4 is fixed to the frame 2, and a thruster 15 made of resin or the like is fixed to the frame 2. A sleeve 6 is fixed to the frame 1, and the frame 1 and the frame 2 are connected by screws or the like to form a stator unit 7. Further, a magnet 9 is fixed to the rotary shaft 8, a ring 10 made of resin or the like is arranged between the magnet 9 and the sleeve 6, constitutes a rotor unit 11, and is rotatably attached via a bearing. ing. The ring 10 prevents direct contact between the magnet 9 and the sleeve 6 when vibration occurs during transportation or when the electric motor is tilted, and prevents abnormal noise or cracking of the magnet 9.

Here, the bearing will be described with reference to FIG. Dynamic pressure generating grooves 12a and 12b are formed by ball rolling or the like at two locations on the inner and outer sides of the sleeve on the load side and the anti-load side, and oil 13 is lubricated as lubricating oil. The generation grooves 12a and 12b form radial bearings 14a and 14b with a gap of several μm maintained therebetween. The end face of the rotating shaft 8 on the side opposite to the load side is finished into a spherical surface and comes into contact with the thruster 15 to form a thrust bearing 16.
Further, oil reservoirs 17a, 17b, 17c having an inner diameter larger than that of the dynamic pressure generating groove portions are provided on the inner peripheral surfaces of the sleeves on both sides of the dynamic pressure generating grooves 12a, 12b. 18b is provided to prevent evaporation and scattering of the oil 13.

[0004]

However, in the configuration of such a conventional electric motor, as shown in FIG. 10, the ring 1 is subject to vibration during transportation (see arrow) or when the electric motor is tilted.
0 and the sleeve 6 come into contact with each other to form a very narrow gap, and the impact of the contact and the capillary phenomenon cause the oil 1 in the dynamic pressure generating grooves 12a and 12b to enter the gap between the ring 10 and the sleeve 6.
However, there was a problem that the reliability of the electric motor was remarkably deteriorated, such as that 3 escaped and an oil shortage occurred.

Further, since the conventional oil 13 is applied to the dynamic pressure generating grooves 12a and 12b and then the sleeve 6 is inserted into the rotary shaft 8, the oil 13 remains at the tip of the rotary shaft 8 and the residual oil is retained. A wiping step for wiping off the oil 13 is generated, and the oil 13 causes the dynamic pressure generating grooves 12a, 1
There is a problem that the required amount remains in 2b and the reliability is poor.

SUMMARY OF THE INVENTION The first object of the present invention is to solve the above problems, and to provide a highly reliable electric motor by eliminating the oil shortage due to the contact between the ring and the sleeve to form a very narrow gap. To do. A second object of the present invention is to provide an electric motor capable of eliminating the oil wiping step and reliably injecting oil into the dynamic pressure generation groove.

[0007]

To this end, the present invention comprises a rotary shaft sleeve, wherein a dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the rotary shaft and the inner peripheral surface of the sleeve. In a motor using a hydrodynamic bearing that holds oil in a pressure generating groove, a ring is arranged near the sleeve, and a counterbore is provided on a contact surface of the ring with the sleeve.

[0008]

With the above construction, the electric motor of the present invention can prevent the oil in the dynamic pressure generating groove from escaping into the gap between the ring and the sleeve and prevent the oil shortage.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view of an electric motor according to a first embodiment of the present invention, and FIGS. 2 and 3 are sectional views of a radial bearing portion of the electric motor. In FIG. 1, FIG. 2, and FIG. 3, a substrate 23 having Hall elements and the like is installed on a stator 22 around which a coil 21 is wound. This stator 22 is one frame 2
The thruster 35 is made of resin or the like and is fixed to the frame 24. A sleeve 26 is fixed to the other frame 25, and the frame 24 and the frame 25 are connected by screws or the like to form a stator unit 27. A magnet 29 is fixed to the rotating shaft 28, and an elastic resin or the like (for example, PES or PBT) is provided between the magnet 29 and the sleeve 26.
A ring 30 made of the same) is arranged, constitutes a rotor unit 31, and is rotatably attached via a bearing.

In FIG. 2, the sleeve 26 of the ring 30 is shown.
On the contact surface 30a with the groove 26, a counterbore having a diameter D2 larger than the inner diameter D1 of the end of the sleeve 26 on the ring side and a depth h larger than the gap between the inner diameter D1 of the end of the sleeve 26 on the ring side and the outer diameter D1 of the rotating shaft. Have In this embodiment, D
1 is φ3.20, D3 is φ3.100, and the ring 30
The diameter D2 of the counterbore provided in the above is set to φ4.0 and the depth h is set to 0.5, but of course, it is not limited to these numerical values.

Next, the bearing will be described with reference to FIG. Dynamic pressure generating grooves 32a and 32b are formed by ball rolling or the like at two positions on the inner circumference of the sleeve on the load side and the anti-load side, and oil 33 is injected as lubricating oil to rotate the rotary shaft 28.
And the dynamic pressure generating grooves 32a and 32b of the sleeve 26 are several μm.
The radial bearings 34a and 34b are formed with the gaps maintained. The end face of the rotary shaft 28 on the side opposite to the load side is finished to be spherical, and comes into contact with the thruster 35 to form a thrust bearing 36. A copper alloy or the like is usually used as the sleeve material.

The rotating shaft material is S45C, SUS303, S
US420J2 or the like can be used depending on the application, but especially when the operating temperature range is wide, a material having a linear expansion coefficient close to that of the sleeve material is preferable. For example, when the sleeve material is a copper alloy, SUS303 or the like should be used as the rotating shaft material. Is preferred. As the oil, diester, polyol ester, a-olefin, mineral oil, fluorine or the like is used, and some additives are added depending on the conditions. Further, on the inner peripheral surfaces of the sleeves on both sides of the dynamic pressure generating grooves 32a, 32b, oil reservoirs 37a, 3 having an inner diameter larger than that of the dynamic pressure generating grooves are formed.
7b and 37c are provided, and projections 38a and 38b are provided at both ends of the inner circumference of the sleeve to prevent evaporation and scattering of the oil 33.

The operation of the above structure will be described with reference to FIG. 3. Even if the ring 30 and the sleeve 26 come into contact with each other to form a very narrow gap due to vibration during transportation or when the motor is tilted, the ring 30 is provided. The counterbore causes the dynamic pressure generation groove 32.
The oil 33 of a and 32b does not escape to the gap between the ring 30 and the sleeve 26 due to the capillary phenomenon, and the reliability of the electric motor can be maintained.

FIG. 4 is a sectional view of an electric motor according to a second embodiment of the present invention, and FIGS. 5 and 6 are sectional views of a radial bearing portion of the electric motor. 4 and 5 and 6, a stator 42 around which a coil 41 is wound, a substrate 43 including a Hall element, etc.,
A thruster 44 made of resin or the like is fixed to the frame 45, and the frame 45 and the frame 46 are connected by screws or the like. Sleeves 49 and 50 held by sleeve holders 47 and 48 are provided on the frames 45 and 46, respectively.
Are installed and constitute the stator unit 51. A magnet 53 is fixed to the rotary shaft 52,
A ring 5 made of an elastic resin or the like (for example, PES or PBT) is provided between the magnet 53 and the sleeve 49.
4 is arranged, constitutes a rotor unit 55, and is rotatably attached via a bearing.

In FIG. 5, the sleeve 49 of the ring 54
A counterbore 54a having a diameter h larger than the inner diameter D1 of the ring-side end of the sleeve 49 and a depth h larger than the gap between the inner diameter D1 of the sleeve-side end of the sleeve 49 and the outer diameter D3 of the rotating shaft. Have In this embodiment, D
1 is ψ3.20, D3 is ψ3.100, and the ring 30
The diameter D2 of the counterbore provided at is φ4.0 and the depth h is 0.5.

Next, the bearing will be described with reference to FIG. One each on the inner peripheral surface of the sleeves 49, 50,
A dynamic pressure generating groove 56 is formed by ball rolling or the like, oil 58 is injected as lubricating oil, and the rotary shaft 52 and sleeve 4
The dynamic pressure generating grooves 56 of 9, 50 form radial bearings 59 with a gap of several μm maintained therebetween. Sleeve 49,
The outer circumference of 50 is spherically shaped and held by sleeve holders 47 and 48 made of resin or the like, so that the sleeves 49 and 50 and the rotary shaft 52 are always concentric. Further, the end face of the rotating shaft 52 on the side opposite to the load side is finished into a spherical surface and comes into contact with the thruster 44 to form the thrust bearing 61. Further, oil reservoirs 62a, 62b having an inner diameter larger than that of the dynamic pressure generating groove 56 are provided on the sleeve inner peripheral surfaces on both sides of the sleeves 49, 50, respectively.
Further, protrusions 64a and 64b are provided on both ends of the inner circumferences of the sleeves 49 and 50, respectively, to prevent evaporation and scattering of the oil 58.

FIG. 7 is a sectional view of the electric motor of the third embodiment of the present invention. 7, the same parts as those in FIG. 1 are designated by the same reference numerals. The conventional oil 33 is injected by the dynamic pressure generating groove 32.
a and 32b and then the sleeve 26 is inserted into the rotary shaft 28, the oil 33 remains at the tip of the rotary shaft 28, and a wiping step for wiping off the residual oil 33 occurs. Dynamic pressure generating grooves 32a, 3
It was difficult to keep the required amount in 2b. Therefore, in this third embodiment, the oil filling hole 71 is provided in the sleeve 26 and the frame 25, and after inserting the sleeve 26 into the rotary shaft 28, the oil 33 is oiled from the oil filling hole 71.
It is possible to omit the wiping step of No. 3 and to surely inject the oil 33 into the dynamic pressure generating grooves 32a and 32b, reduce the excess oil 33, and prevent the oil 33 from scattering.

It is needless to say that the electric motor structure, electric motor type, bearing structure, oil, etc. are not limited to each embodiment, and various design changes are possible. Further, in the above embodiment, the material of the ring is the resin having elasticity, but other materials having the same function may be used.

[0019]

As described above, according to the present invention, the counterbore provided on the ring causes the oil in the dynamic pressure generating groove to enter the gap between the ring and the sleeve due to the capillary phenomenon due to vibration during transportation or tilting of the electric motor. Since it does not run away, it is possible to obtain a highly reliable electric motor that can be smoothly operated.

Further, since the oiling hole is provided in the sleeve, and the oil is oiled from the oiling hole after the sleeve is inserted into the rotary shaft, the oil wiping step can be omitted, and further the oil can be supplied to the dynamic pressure generating groove. It enables reliable lubrication, reduction of excess oil, and prevention of oil scattering.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a radial bearing portion of the electric motor according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a radial bearing portion of the electric motor according to the first embodiment of the present invention.

FIG. 4 is a sectional view of an electric motor according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a radial bearing portion of an electric motor according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a radial bearing portion of an electric motor according to a second embodiment of the present invention.

FIG. 7 is a sectional view of an electric motor according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view of a conventional electric motor

FIG. 9 is a sectional view of a radial bearing portion of a conventional electric motor.

FIG. 10 is a sectional view of a radial bearing portion of a conventional electric motor.

[Explanation of symbols]

 26, 49, 50 Sleeve 28, 52 Rotating shaft 30, 54 Ring 32a, 32b, 56 Dynamic pressure generating groove 33, 58 Oil 71 Lubrication hole

Claims (3)

[Claims] 1. A rotary shaft and a sleeve are provided, and a dynamic pressure generating groove is formed on at least one of an outer peripheral surface of the rotary shaft and an inner peripheral surface of the sleeve, and the dynamic pressure generating groove holds oil. An electric motor using a hydrodynamic bearing,
A motor is characterized in that a ring is arranged in the vicinity of the sleeve, and a counterbore is provided on a contact surface of the ring with the sleeve. 2. The diameter of the counterbore is made larger than the inner diameter of the ring side end of the sleeve, and the depth of the counterbore is made larger than the gap between the inner diameter of the ring side end of the sleeve and the outer diameter of the rotary shaft. The electric motor according to claim 1, wherein: 3. A rotary shaft and a sleeve are provided, and a dynamic pressure generating groove is formed on at least one of an outer peripheral surface of the rotary shaft and an inner peripheral surface of the sleeve, and the dynamic pressure generating groove holds oil. An electric motor using a hydrodynamic bearing,
An electric motor characterized in that a radial hole is provided in the vicinity of the dynamic pressure generation groove as means for injecting oil into the dynamic pressure generation groove.