JPH02299440A - Spindle motor - Google Patents

Abstract

PURPOSE:To reduce the deterioration of dimensional accuracy and rotating accuracy accompanied by the deterioration of the dimensional accuracy by a method wherein a rotary shaft, to which a rotor equipped with permanent magnets is attached, is supported through oil mist lubricating bearings and the inside of a machine is cooled by passing air mixed with oil mist while a frame is cooled by passing cooling water. CONSTITUTION:A rotary shaft 2, to which a rotor 1 equipped with cylindrical permanent magnets 6 is attached, is supported by oil mist lubricating bearings 3, 4 and the inside of a machine is cooled by passing air mixed with oil mist while a frame 5 is cooled by passing cooling water. In this case, the temperature gradients of respective parts are reduced and, further, the inside of the machine is cooled by air mixed with the oil mist while the frame 5 is cooled effectively by cooling water. According to this method, the temperature gradients may be eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention solves the problem of reducing the dimensional accuracy of various parts due to the heat generated during operation and the accompanying reduction in rotational accuracy in spindle motors that require high rotational accuracy. Regarding things that can be reduced.

[Conventional technology]

For spindle motors, -1113 uses a squirrel-cage rotor, and in order to suppress temperature rises during operation, cooling air is sent into the machine, and cooling air or cooling water is passed through the frame, rotating shaft, etc. to cool the motor. Ta.

[Problem to be solved by the invention]

In the above structure, the temperature of the rotor rises due to the heat generated by the rotor current, creating a temperature gradient in each part, which may cause, for example, a decrease in the dimensional accuracy of the mounting surface or the end of the rotating shaft, resulting in a decrease in rotation accuracy. There was a drawback.

In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to provide a spindle motor that can reduce the reduction in dimensional accuracy of each part due to heat generated during operation and the accompanying reduction in rotational accuracy. do.

[Means to solve the problem]

In order to achieve the above object, this invention supports a rotating shaft 2 on which a cylindrical permanent magnet rotor 1 is fitted with an oil mist lubricated bearing 3.4, and cools the inside of the machine by passing air mixed with oil mist. At the same time, the frame 5 is cooled by passing cooling water.

[Effect]

Unlike the squirrel-cage rotor described in the prior art, the rotor 1 with permanent magnets does not generate heat due to electric current, so the temperature gradient in each part is small. Since each of the parts is effectively cooled with cooling water, the temperature gradient can be almost eliminated, thereby reducing the decrease in dimensional accuracy of each part and the accompanying decrease in rotation accuracy.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which a rotating shaft 2 is fitted with a cylindrical rotor 1 having permanent magnets 6 embedded therein.
It is supported at the center of a frame 5 having a U-shaped cross section and a disc-shaped bracket 7 attached to the tip end surface of the frame 5 through combination bearings 3 and 4, which are combined in stages and two stages to provide rotational precision. The bearings 3 and 4 are lubricated with oil mist, and this oil mist is supplied to the frame 5 and bracket 7 through oil supply passages 8 and 9 provided in the radial direction from the outer periphery. The oil mist that has lubricated the bearings 3 and 4 passes through the interior of the machine as shown by the arrow P while being mixed with air, cools it down, and then is discharged from a radial oil drain path 10 provided in the frame 5.

A stator 1 surrounding the rotor 1 is disposed on the inner periphery of the frame 5.
1 is fitted, and the stator 11, bearing 3, and frame 5 are cooled by passing cooling water through a water passage 12 provided through the frame 5.

Water can pass through the water passage 12 through the frame 5 in the axial direction from the outer periphery of the outer surface of the bracket 7, and then through annular water passages 12a and 12b formed near the outer peripheries of the bearing 3 and stator 11, respectively. ing.

According to the embodiment, the rotor 1 with permanent magnets does not generate heat due to electric current unlike the squirrel cage rotor described in the prior art, so the temperature gradient in each part is small, and furthermore, the rotor 1 with permanent magnets does not generate heat due to electric current, and the temperature gradient in each part is small. The stator 11 is also a heat source.
Since the bearing 3 and the frame 5 are each effectively cooled with cooling water, the temperature gradients mentioned above can be almost eliminated and the decrease in dimensional accuracy of each part can be reduced. For example, in the experimental apparatus shown in FIG. 2, the mounting of the motor 13 is based on the experimental results of measuring the amount of change in deflection of the tip of the rotating shaft 2 with respect to the surface.As shown in FIG. It can be seen that the number is significantly reduced compared to B, which was explained in .

In the embodiment described above, a case has been described in which the bearings 3 and 4 are a combination of four-stage and two-stage bearings, but the present invention is not limited thereto.

〔Effect of the invention〕

According to this invention, in a spindle motor, a rotating shaft fitted with a permanent magnet rotor is supported by an oil mist lubricated bearing, and the inside of the machine is cooled by passing air mixed with oil mist, and the frame is cooled by passing cooling water. As a result, temperature gradients in various parts due to heat generated during operation can be almost eliminated (thus reducing the decrease in dimensional accuracy and the accompanying decrease in rotational accuracy).

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, Fig. 2 is a schematic configuration diagram of an experimental apparatus for measuring rotational accuracy of the motor shown in Fig. 1, and Fig. 3 shows measured values of rotational accuracy of the motor shown in Fig. 1. It is a curve diagram. 1... Rotor, 2... Rotating shaft, 3, 4... Bearing,
5... Frame, 6... Permanent magnet, 13... Motor. Figure 2 → J rotation amount H) Figure 3

Claims (1)

[Claims] 1) A rotating shaft fitted with a cylindrical permanent magnet rotor is supported by an oil mist lubricated bearing, and the inside of the machine is cooled by passing air mixed with oil mist, and the frame is cooled by passing cooling water. Spindle motor.