JPH03173329A - High speed rotor - Google Patents

Abstract

PURPOSE:To protect a permanent magnet from breakdown by arranging a nonmagnetic stress relax layer for relaxing concentration of stress due to centrifugal force between the permanent magnet and a sleeve. CONSTITUTION:When a rotor is rotary driven with high speed by the exhaust energy, the rotor is subjected to a strong centrifugal force and thereby a permanent magnet 2, a stress relax layer 4 and a sleeve 3 are subjected to tensile stress in the outer direction. Since stiff metal is employed for the outermost sleeve 3 and a nonmagnetic stress relax layer 4 is burried in the gap at the inside, strong centrifugal force of the permanent magnet 2 is transmitted uniformly to the sleeve 3 without causing concentration of stress at the gap due to imperfect roundness or the surface irregularity, thus relaxing the stress. By such arrangement, the permanent magnet 2 can be protected against breakdown even under super high speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultra-high-speed rotor of a rotating electrical machine that is directly connected to an ultra-high-speed rotating turbine shaft.

(Prior art) In recent years, turbochargers have been widely used, which guide exhaust gas emitted by an internal combustion engine to a turbine, drive it at high speed, drive a compressor attached to the turbine shaft, and forcefully send supercharged air to the internal combustion engine. .

Then, a rotating electrical machine that serves as an electric generator is attached to the turbine shaft of this type of turbocharger, and the exhaust energy is recovered as electric power through power generation operation, or power is supplied from a battery to supercharge the electrically operated Nyote compressor. Efforts are being made to assist in movement.

Since the rotor of such a rotating electric machine placed on the turbine shaft rotates at an ultra-high speed of 100,000 revolutions per minute or more, the applicant has developed a permanent magnet made of a magnetic material containing rare earth elements on the outer circumferential surface of the rotating magnetic pole. A proposal for an ultra-high-speed rotor in which a sleeve that applies compressive stress in the central axis direction to a permanent magnet is fitted has been filed in Patent No. 217110 of 1989.

(Problems to be Solved by the Invention) The material for the sleeve in the above-mentioned proposal is required to have high bow tensile strength, low specific gravity, be hard to stretch at the size of young grass, and be non-magnetic.

The mechanical properties of the rare earth cobalt magnet, which is the magnet material, are similar to those of ceramics, as shown in Figure 3, without undergoing plastic deformation, and the permanent magnet tends to expand in the outer circumferential direction due to centrifugal force during high-speed rotation. However, the sleeve fitted around the outer periphery suppresses the expansion and avoids destruction.

Now, if we focus on the part where the permanent magnet and the sleeve fit together,
As shown in the partially enlarged views of FIGS. 4 and 5, gaps are created due to the respective roundness and surface roughness, and stress concentration occurs in the gaps.

The mechanism of destruction of permanent magnets is due to the progression of cracks as explained by Griffith's fracture theory, and when stress concentration occurs as described above, microscopic damage occurs during machining of permanent magnets in the vicinity. There is a risk that the cracks will increase and lead to destruction.

The present invention was made in view of such problems,
The purpose is to provide an ultra-high-speed rotor that focuses on the gap between the permanent magnet and the outer sleeve and prevents the permanent magnet from being destroyed even during ultra-high-speed rotation.

(Means for Solving the Problems) According to the present invention, rotation of a permanent magnet made of a magnetic material containing rare earth elements iii! An ultra-high-speed rotor in which a reinforcing sleeve is fitted to the outer peripheral surface of the pole, and a stress-relaxation layer made of a non-magnetic material is provided between the permanent magnet and the sleeve to alleviate stress concentration caused by centrifugal force. A high speed rotor is provided.

(Function) In the present invention, a stress relaxation layer made of a soft metal or a polymeric material is provided between the permanent magnet made of a magnetic material containing rare earth elements and the sleeve on the outer periphery. The gap is filled with the stress relaxation layer, eliminating the gap. Therefore, stress concentration due to centrifugal force when the rotor rotates at high speed does not occur, and the stress becomes uniform, thereby preventing damage to the permanent magnet.

(Example) Next, an example of the present invention will be described in detail using the drawings.

FIGS. 1(a) and 1(b) are cross-sectional views showing one embodiment of the present invention.

In the figure, reference numeral 1 denotes a rotating shaft made of high-strength steel, on which a turbocharger turbine and a compressor are arranged on the left and right sides, and a permanent magnet 2 serving as a rotating magnetic pole is attached in between.

The permanent magnet 2 is made of a magnetic material containing a rare earth element, and is formed into a thick cylindrical shape using a rare earth magnet such as samarium-cobalt. It is configured to generate electricity through electromagnetic interaction with the stator of a rotary electric machine, and to rotate as an electric motor when a predetermined amount of power is supplied to the stator.

Reference numeral 3 denotes a thin sleeve 5 made of a strong non-magnetic titanium alloy or other metal to form the outer periphery of the rotor. A stress relief layer 4 of corresponding thickness is fitted as shown.

Note that the stress relaxation R4 is made of a soft and easily deformable non-magnetic metal such as copper or aluminum, or a polymeric material, and the above-mentioned stress relaxation R4 is made of a material such as a polymer material or a soft non-magnetic metal such as copper or aluminum. Either a material is surface-treated and placed between the permanent magnet 2 and the sleeve 3, or a thin plate of the above-mentioned material is wrapped around the outer circumference of the permanent magnet 2, and this is inserted into the inner surface of the sleeve 3 to tightly secure it. They are fitted together.

Reference numeral 5 denotes a side plate made of high-strength material, which is fixed to the end of the rotating shaft 1 and the sleeve 3 so as to prevent the stress relaxation layer 4 and the permanent magnet 2 from being deformed in the axial direction of the rotating shaft 1 due to centrifugal force. There is.

FIG. 2 is a sectional view of a turbocharger with a rotating electric machine to which this embodiment is applied.

Next, referring to the sectional view of FIG. 2, the turbocharger lO is compressed by the exhaust energy of the engine (not shown), compresses air, and supplies this pressurized air to the engine as supercharging air.

11 is a turbine driven by the exhaust gas from the exhaust pipe 12, and 13 is a compressor connected to the turbine 11 by rotation @1 and driven to rotate, compressing air from the intake air port 14 and sending it to the engine. It is something to do.

15 is a bearing, which supports the rotating shaft 1;
A rotating shaft 1 between the bearing 15 and the compressor 13
The permanent magnet 2 described above is attached as a rotating magnetic pole.

A stator 8 electromagnetically corresponds to the rotor of the permanent magnet 2, and has a core 81 and a coil 82.

When the exhaust energy from the engine is large and there is surplus power for supercharging the turbocharger 10, the electric power generated in the coil 82 of the stator 8 is reduced by the change in magnetic flux caused by the permanent magnet 2 driven at ultra-high speed. When the battery is charged as a power source, or when the engine is running at low speed and high load with little exhaust energy and sufficient boost pressure cannot be obtained from the turbocharger 10, the electric energy from the battery is transferred to the stator 8. The system is configured to supply the fuel to move the rotor, energize the supercharging operation of the compressor 13, and increase the boost pressure to the engine.

Next, the operation of this embodiment configured as described above will be explained.

When the rotor configured as described above is driven to rotate at ultra-high speed by exhaust energy, a strong centrifugal force is applied to the rotor outward from the central axis, and the permanent magnet 2 and the stress relaxation layer 4
, and sleeve 3 are subjected to outward tensile stress.

The outermost sleeve 3 is made of strong metal, and inside it there is a stress relaxation layer 4 that fills the gap.
The strong outward centrifugal force applied to the permanent magnet 2 is transmitted almost uniformly to the sleeve 3, and the stress is alleviated, without causing stress concentration due to gaps due to its roundness or surface roughness. That will happen.

Although the present invention has been described in detail using the above-mentioned embodiments, various modifications can be made within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) According to the present invention, the stress of the soft material that fills the gap between the permanent magnet made of the magnetic material containing rare earth elements and the reinforcing sleeve based on the roundness and surface roughness of each Since the relaxation layer is provided, uniform stress is applied to the strong centrifugal force caused by the rotor's high-speed rotation without stress concentration. Also, the increase in scratches is prevented and damage is avoided,
The effect is that stable ultra-high speed rotation can be obtained.

[Brief explanation of the drawing]

Fig. 1 (a, b) is a sectional view showing one embodiment of the present invention, Fig. 2 is a sectional view of a turbocharger with a rotating electric machine to which this embodiment is applied, and Fig. 3 is a relationship between strain and stress. curve diagram, 4th
The figure is an explanatory diagram of the roundness of the material and the gap, and FIG. 5 is an explanatory diagram of the surface roughness of the material and the gap. 1... Rotating shaft, 2... Permanent 61 stones, 3... Sleeve, 4... Stress relaxation layer.

Claims (3)

[Claims] (1) In an ultrahigh-speed rotor in which a reinforcing sleeve is fitted to the outer peripheral surface of the rotating magnetic pole of a permanent magnet made of a magnetic material containing rare earth elements, between the permanent magnet and the sleeve,
An ultra-high-speed rotor characterized by having a stress relaxation layer made of a non-magnetic material that relieves stress concentration caused by centrifugal force. (2) The ultrahigh-speed rotor according to claim 1, wherein the stress relaxation layer is a thin layer made of a soft metal. (3) The ultrahigh-speed rotor according to claim (1), wherein the stress relaxation layer is a thin layer made of a polymeric material.