A composite permanent magnet for a synchronous permanent magnet motor rotor

Abstract

The present invention discloses a composite permanent magnet for a synchronous permanent magnet motor rotor, comprising a permanent magnet, a permanent magnet bracket and a permanent magnet sheath, wherein the two permanent magnets are symmetrically fixedly connected to the outer wall of the permanent magnet bracket, and the permanent magnet and the permanent magnet bracket form a cylindrical composite permanent magnet unit with a smooth outer wall surface, the permanent magnet sheath is sleeved on the composite permanent magnet unit, and the permanent magnet sheath and the composite permanent magnet unit are interference fit; the permanent magnet bracket is made of low carbon steel. The present invention saves permanent magnet material consumption, greatly reduces costs, can directly replace the original cylindrical permanent magnet parts, does not need to change the production line, can replace high-strength alloy steel with austenitic stainless steel, and reduces the cost of permanent magnet sheath materials.

Description

Technical field:

[0001] The invention relates to a composite permanent magnet of a synchronous permanent magnet motor rotor. Background technology:

[0002] Due to the high speed, the volume of the magnetic levitation motor is much smaller than that of ordinary motors. Therefore, some medium-power magnetic levitation permanent magnet motors use simple-to-manufacture integral permanent magnets. There are two advantages to this: first, the rotor structure is simple and easy to manufacture; second, the rotor core shaft can be made of non-magnetic materials to prevent the magnetism of the rotor permanent magnet from interfering with the work of the magnetic bearing.

[0003] But the disadvantages of integral permanent magnets are also obvious:

[0004] 1) The amount of permanent magnetic material used is large, the cost is high and the resources are wasted.

[0005] 2) The permanent magnet sheath has great stress and must be made of expensive high-strength alloy material.

[0006] Since the operating temperature of the rotor can reach above 100°C, the thermal expansion coefficient of the permanent magnet is close to 0, and the thermal expansion coefficient of the sheath is 12-16, the sheath and the permanent magnet tend to loosen during operation.

[0007] In order to maintain a reliable interference fit between the permanent magnet and the sheath and offset loosening caused by thermal expansion differences, the sheath stress is very high (up to 700-1000 MPa in some cases), so expensive high-strength alloy materials must be used. Summary of the invention:

[0008] The present invention provides a composite permanent magnet for a synchronous permanent magnet motor rotor in order to solve the problems existing in the prior art.

[0009] The technical scheme adopted by the present invention is as follows: a composite permanent magnet of a synchronous permanent magnet motor rotor, comprising a permanent magnet, a permanent magnet bracket and a permanent magnet sheath, wherein two permanent magnets are symmetrically fixedly connected to the outer wall of the permanent magnet bracket, and the permanent magnet and the permanent magnet bracket form a cylindrical composite permanent magnet unit with a smooth outer wall surface, the permanent magnet sheath is sleeved on the composite permanent magnet unit, and the permanent magnet sheath and the composite permanent magnet unit are interference fit;

[0010] The permanent magnet bracket is made of low carbon steel.

[0011] Furthermore, the permanent magnet bracket includes a cylindrical body, and two rectangular installation grooves are symmetrically provided on the outer circumferential wall of the body, and the two installation grooves are arranged along the axial direction of the body.

[0012] Furthermore, the permanent magnet is bonded in the installation groove by epoxy adhesive, and an arc surface is provided on the permanent magnet. After the permanent magnet is fixed in the installation groove, the arc surface of the permanent magnet and the outer wall surface of the body together form a smooth cylindrical outer wall surface.

[0013] Furthermore, the permanent magnet sheath is made of austenitic stainless steel.

[0014] The present invention has the following beneficial effects:

[0015] 1) Save permanent magnet material consumption and greatly reduce costs:

[0016] Since a part of the permanent magnet material is replaced by a permanent magnet bracket made of low carbon steel, the consumption of permanent magnet material can be reduced by about 50%, and the cost of the permanent magnet is also reduced by nearly 50%.

[0017] 2) It can directly replace the original cylindrical permanent magnet parts without changing the production line:

[0018] The overall shape of the composite permanent magnet is still cylindrical, which is consistent with the original solid permanent magnet. Therefore, the composite permanent magnet parts can be directly used to replace the solid permanent magnets on the original production line without adjusting and changing the production line.

[0019] 3) Austenitic stainless steel can be used to replace high-strength alloy steel to reduce the cost of permanent magnet sheath materials:

[0020] Since the thermal expansion coefficient of low carbon steel is consistent with that of the sheath, it will not loosen from the permanent magnet sheath due to thermal expansion during operation, so the interference fit of the sheath can be greatly reduced and the sheath stress can be reduced (to as low as 200-250Mpa), thereby using low-cost austenitic stainless steel material to manufacture the permanent magnet sheath. This change alone can reduce the manufacturing cost of the permanent magnet sheath by more than 70%. Description of the drawings:

[0021] Figure 1 This is a structural diagram of the present invention.

[0022] Figure 2 This is a structural diagram of a composite permanent magnet unit composed of a permanent magnet and a permanent magnet bracket in the present invention.

[0023] Figure 3 It is an exploded view of the present invention. Specific implementation method:

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] like Figures 1 to 3The present invention discloses a composite permanent magnet for a synchronous permanent magnet motor rotor, comprising a permanent magnet 1, a permanent magnet bracket 2 and a permanent magnet sheath 3. The two permanent magnets 1 are symmetrically fixedly connected to the outer wall of the permanent magnet bracket 2, and the permanent magnet 1 and the permanent magnet bracket 2 form a cylindrical composite permanent magnet unit with a smooth outer wall surface. The permanent magnet sheath 3 is sleeved on the composite permanent magnet unit, and the permanent magnet sheath 3 and the composite permanent magnet unit are interference fit.

[0026] The permanent magnet bracket 2 of the present invention comprises a cylindrical body 21 , and two rectangular mounting grooves 22 are symmetrically provided on the outer circumferential wall of the body 21 . The two mounting grooves 22 are arranged along the axial direction of the body 21 .

[0027] The permanent magnet 1 is bonded in the mounting groove 22 by epoxy adhesive. A circular arc surface is provided on the permanent magnet 1. After the permanent magnet 1 is fixed in the mounting groove 22, the circular arc surface of the permanent magnet 1 and the outer wall surface of the body 21 form a smooth cylindrical outer wall surface.

[0028] The permanent magnet bracket 2 in the present invention is made of low-carbon steel, and the permanent magnet sheath 3 is made of austenitic stainless steel.

[0029] The "I"-shaped permanent magnet bracket 2 made of low-carbon steel is used to fix two "tile-shaped" permanent magnets 1, achieving the same electromagnetic characteristics as the surface-mounted structure.

[0030] The permanent magnet 1 and the permanent magnet bracket 2 are bonded and assembled with epoxy glue. After the permanent magnet 1 and the permanent magnet bracket 2 are assembled, the shape of the entire composite permanent magnet unit is cylindrical. After the composite permanent magnet unit is assembled, the entire unit is subjected to external cylindrical grinding so as to be assembled with the permanent magnet sheath 3.

[0031] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A composite permanent magnet for a synchronous permanent magnet motor rotor, characterized in that: It comprises a permanent magnet (1), a permanent magnet support (2) and a permanent magnet sheath (3), wherein the two permanent magnets (1) are symmetrically fixedly connected to the outer wall of the permanent magnet support (2), and the permanent magnet (1) and the permanent magnet support (2) form a cylindrical composite permanent magnet unit with a smooth outer wall surface, and the permanent magnet sheath (3) is sleeved on the composite permanent magnet unit, and the permanent magnet sheath (3) and the composite permanent magnet unit are interference fit; The permanent magnet bracket (2) is made of low carbon steel; The permanent magnet (1) and the permanent magnet bracket (2) are bonded and assembled with epoxy glue. After the permanent magnet (1) and the permanent magnet bracket (2) are assembled, the shape of the entire composite permanent magnet unit is cylindrical. After the composite permanent magnet unit is assembled, the entire unit is subjected to external cylindrical grinding so as to be assembled with the permanent magnet sheath (3). The permanent magnet bracket (2) comprises a cylindrical body (21), and two rectangular mounting grooves (22) are symmetrically provided on the outer circumferential wall of the body (21), and the two mounting grooves (22) are arranged along the axial direction of the body (21); The permanent magnet (1) is bonded in the mounting groove (22) by epoxy adhesive, and a circular arc surface is provided on the permanent magnet (1). After the permanent magnet (1) is fixed in the mounting groove (22), the circular arc surface of the permanent magnet (1) and the outer wall surface of the body (21) together form a smooth cylindrical outer wall surface; The permanent magnet sheath (3) is made of austenitic stainless steel.

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