Permanent magnet motor with an embedded rotor structure and method of assembling the same

Abstract

This invention provides a permanent magnet motor with an embedded rotor structure and its assembly method. The permanent magnet motor with an embedded rotor structure includes a stator core and a rotor core. The rotor core is provided with magnet slots for accommodating magnets, and a glue storage groove is provided on the side of the magnet slot near the outer ring of the rotor core. By providing a built-in glue storage groove, the permanent magnet motor with an embedded rotor structure of this invention increases the reliability of glue bonding and prevents magnets from falling off during high-speed motor rotation; it also increases the back electromotive force of the motor and reduces motor losses.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a permanent magnet motor with an embedded rotor structure and its assembly method. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) use permanent magnets for excitation, simplifying the motor structure, reducing processing and assembly costs, and eliminating the need for potentially problematic slip rings and brushes, thus improving operational reliability. Furthermore, the absence of excitation current and excitation losses increases efficiency and power density. A PMSM consists of a stator, rotor, and end covers. The stator is essentially the same as a conventional induction motor, employing a laminated structure to reduce iron losses during operation. The rotor can be solid or formed from laminated sheets, with permanent magnet material mounted on it. Depending on the location of the permanent magnet material on the rotor, PMSMs can be classified into two structural types: protruding and embedded. Protruding rotors have a simpler magnetic circuit structure and lower manufacturing costs, but because starting windings cannot be mounted on their surface, asynchronous starting is not possible.

[0003] There are three main types of magnetic circuit structures for built-in rotors: radial, tangential, and hybrid. The main difference between them lies in the relationship between the magnetization direction of the permanent magnet and the rotor's rotation direction. Because the permanent magnet is placed inside the rotor, pole shoes can be formed on the rotor surface. The pole shoes, incorporating copper bars or cast aluminum, can serve for starting and damping, resulting in good steady-state and dynamic performance. Furthermore, the asymmetrical magnetic circuit of the built-in rotor generates reluctance torque during operation, which helps improve the motor's power density and overload capacity. This structure also facilitates field weakening for speed extension.

[0004] like Figure 1 and Figure 2 As shown, the electromagnetic structure of a traditional permanent magnet synchronous motor mainly consists of a stator core 10, windings 12, magnets 14, a rotor core 11, and a shaft 15. An air gap 13 is formed between the stator core 10 and the rotor core 11. Depending on the installation position of the magnets, permanent magnet synchronous motors can be classified as follows: Figure 1 The surface mount type and such Figure 2 The magnets in both the built-in and surface-mount permanent magnet synchronous motors shown are easy to optimize, allowing the air gap magnetic field waveform to approach a sine wave. However, compared to traditional built-in motors, their magnet processing technology is more complex, resulting in higher processing costs. The air gap magnetic field waveform distortion rate of built-in permanent magnet motors is generally greater than that of surface-mount motors. The magnet structure is simpler and easier to process. Both types of magnets require adhesive bonding to the rotor core during assembly; otherwise, they will detach from the rotor core under centrifugal and electromagnetic forces during high-speed rotation.

[0005] Because surface-mounted magnets are directly attached to the rotor core surface, adhesive can be applied directly to the core surface, and the core surface typically has an adhesive reservoir, making the adhesive application process relatively simple. For example... Figure 3 As shown, the basic method of applying glue to embedded motors is to brush a layer of glue 16 on the surface of magnet 14 and then insert the magnet into the magnet slot of rotor core. During the insertion process, most of the glue is scraped off by the rotor core, resulting in insufficient adhesion between the magnet and the core, which may cause the magnet to fall off when the motor is running at high speed. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention provides a permanent magnet motor with an embedded rotor structure to solve the problem of difficult glue application in built-in permanent magnet motors. At the same time, it increases the back electromotive force of the motor by adding a glue storage tank and designing the shape of the glue storage tank.

[0007] The present invention provides a permanent magnet motor with an embedded rotor structure, including a stator core and a rotor core. The rotor core is provided with a magnet slot for accommodating magnets, and a glue storage slot is provided on the side of the magnet slot near the outer ring of the rotor core.

[0008] In one embodiment, the glue storage tank is a square tank or a conical tank.

[0009] In one embodiment, the width of the glue storage tank is smaller than the width of the magnet tank.

[0010] In one embodiment, the glue storage tank is located at the middle of one end of the magnet tank, and the centerline of the glue storage tank coincides with the centerline of the magnet tank.

[0011] In one embodiment, the length-to-width ratio of the glue storage tank is 11-13:1.

[0012] In one embodiment, the length-to-width ratio of the glue storage tank is 12:1.

[0013] In one embodiment, the outer wall of the rotor core is provided with a glue injection hole corresponding to the glue storage tank, and the glue injection hole is connected to the corresponding glue storage tank.

[0014] In one embodiment, the injection hole extends radially along the rotor core.

[0015] In one embodiment, the injection hole is located at the center of the outer side of the glue storage tank, and the injection hole communicates with the middle part of the glue storage tank.

[0016] The present invention also provides an assembly method for a permanent magnet motor with the above-mentioned embedded rotor structure, comprising the following steps: first, installing uncoated magnets into the magnet slots of the rotor core, and then injecting adhesive into the adhesive storage tank through the adhesive injection hole on the outer wall of the rotor core.

[0017] Compared with the prior art, the advantages of the present invention are that the permanent magnet motor with embedded rotor structure of the present invention increases the reliability of glue bonding by setting an internal glue storage tank, and prevents the magnets from falling off when the motor rotates at high speed; at the same time, it also increases the back electromotive force of the motor and reduces the motor loss.

[0018] The glue injection process of the permanent magnet motor of the present invention first installs the un-glued magnets into the magnet slots of the rotor core, and then injects glue into the glue storage tank through the glue injection hole. This overcomes the problem that the prior art process of applying glue first and then installing the magnets loses some glue. Moreover, since no glue is applied when installing the magnets, the preset force acting on the magnets can be kept basically unchanged. In contrast, in the prior art, because glue is applied first, the preset force is reduced due to the presence of glue, and ultimately cannot meet the requirements for the preset force. Attached Figure Description

[0019] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0020] Figure 1 A schematic diagram of the electromagnetic component of an existing surface-mounted permanent magnet synchronous motor.

[0021] Figure 2 This is a schematic diagram of the electromagnetic component of an existing embedded permanent magnet synchronous motor.

[0022] Figure 3 A schematic diagram of the assembly of built-in magnets in an existing embedded permanent magnet synchronous motor;

[0023] Figure 4 This is a schematic diagram of the electromagnetic part of the built-in permanent magnet motor in an embodiment of the present invention;

[0024] Figure 5 for Figure 4 Enlarged schematic diagram of a portion of the internal magnetic steel channel;

[0025] Figure 6 This is a schematic diagram of the embedded adhesive coating process for the built-in permanent magnet motor in an embodiment of the present invention;

[0026] Figure 7 This is a comparison diagram of the back EMF waveforms of the built-in permanent magnet motor in an embodiment of the present invention and the existing built-in permanent magnet motor structure.

[0027] Reference numerals: Stator core-20, Rotor core-21, Winding-22, Air gap-23, Magnet-24, Shaft-25, Glue reservoir-26, Glue injection hole-27; Glue gun-28.

[0028] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0029] The invention will now be further described with reference to the accompanying drawings.

[0030] The permanent magnet motor with an embedded rotor structure of the present invention is an embedded permanent magnet synchronous motor, such as... Figure 1 The image shows an existing surface-mounted permanent magnet synchronous motor, such as... Figure 2 The image shows a built-in permanent magnet synchronous motor. The difference between the two is that the magnets in the built-in permanent magnet synchronous motor are located in the magnet slots of the rotor core.

[0031] like Figure 4 As shown, in the permanent magnet motor with an embedded rotor structure of the present invention, the electromagnetic structure of the permanent magnet synchronous rotor motor is largely consistent with the structure of existing permanent magnet synchronous motors. The permanent magnet motor with an embedded rotor structure of the present invention mainly includes a stator core 20, windings 22, a rotor core 21, magnets 24, and a shaft 25. The rotor core 21 is disposed inside the stator core 20, and multiple windings 22 are arranged in an array on the stator core 20. Current is generated in the energized windings and a magnetic field is generated. An air gap 23 is formed between the stator core 20 and the rotor core 21, and a magnetic field is present in the air gap 23. The shaft 25 is connected to the rotor core 21. For example, the shaft 25 is located at the center of the rotor core 21. The rotor core 21 outputs power outward through the shaft 25. Multiple magnet slots extending radially along the rotor core are provided on the rotor core 21, and the magnet slots can be used to accommodate magnets 24.

[0032] like Figure 5 As shown, a glue storage groove 26 is provided on the radially outer side of the magnet slot. For example, the glue storage groove 26 is provided on the side near the outer ring of the rotor core 21. The additional glue storage groove 26 helps to improve the reliability of the adhesive bonding force when the magnet 24 and the core are mated, ensuring that the magnet 24 is stably bonded to the magnet slot on the core. The glue storage groove 26 is preferably a square groove, for example, a square glue storage groove 26 with a length of L and a width of W. Multiple laminations can be stacked to form the glue storage groove 26 when designing the shape and structure of the laminations of the rotor core 21.

[0033] The adhesive can be any adhesive that is suitable for permanent magnet motors in the existing technology, such as epoxy adhesive, Loctite 326 structural adhesive, or Schmindt hard Y-358AB adhesive.

[0034] Preferably, the aforementioned glue storage tank is located at the outer end of the magnet slot, and the width of the glue storage tank is smaller than the width of the magnet slot. The glue storage tank is located at the middle of the outer end of the magnet slot, and the centerline of the glue storage tank coincides with the centerline of the magnet slot. This symmetrical arrangement is beneficial for forming a regular magnetic field on the motor and also facilitates processing and manufacturing.

[0035] A major improvement of the embedded rotor structure permanent magnet motor of the present invention compared with the existing conventional built-in permanent magnet synchronous motor lies in the addition of a glue storage tank 26 structure within the magnet slot. The increased glue storage tank 26 correspondingly increases the magnetic reluctance of the rotor core 21, reducing rotor leakage flux and thus improving the effective magnetic flux of the motor, thereby increasing the back electromotive force (EMF). Since the size and shape of the glue storage tank 26 affect the back EMF performance of the motor, the glue storage tank 26 of the embedded rotor structure of the present invention is preferably a square tank. The dimensions of the square tank preferably satisfy the following characteristics: the length and width of the glue storage tank 26 satisfy the relationship L:W = 11-13:1, preferably L:W = 12:1. Figure 7 As shown, the back electromotive force of the permanent magnet motor using the structure of the present invention is shown as curve B, while the back electromotive force of the existing permanent magnet motor is shown as curve A. In the figure, the horizontal axis represents time, and the vertical axis represents voltage value. The back electromotive force of the permanent magnet motor using the structure of the present invention is higher than that of the permanent magnet motor with the existing structure (the main difference between the two motors in the comparison curves is whether or not a glue storage tank is provided).

[0036] In addition, the adhesive storage tank 26 can also be configured in other shapes, such as a conical tank, with the longer side of the conical tank closer to the magnet tank and the shorter side farther away from the magnet tank, in order to increase the contact area between the conical adhesive storage tank 26 and the magnet tank and increase the bonding area. Alternatively, the longer side of the conical tank can be farther away from the magnet tank and the shorter side closer to the magnet tank to change the magnetic field distribution in the air gap 23.

[0037] The glue storage tank 26 can be a through-slot located at the outer end of the magnet slot, or it can be a hollow slot with a square or frustum-shaped slot in the middle. That is, the glue storage tank 26 has a hollow square or frustum-shaped cavity inside, and the punches at the top and bottom ends do not have cuts. The punches at both ends cover the hollow square or frustum-shaped cavity inside, which can prevent the injected adhesive from flowing out and facilitate the filling of the glue storage tank 26 and the glue injection process.

[0038] like Figure 6 As shown, the rotor core is also provided with a glue injection hole 27 for injecting glue into the glue storage tank 26, and the glue injection hole is connected to the glue storage tank. The glue injection hole can be a radially extending or axially extending hole, such as a cylindrical hole. To facilitate uniform glue injection into the glue storage tank, the glue injection hole is preferably radially extending on the rotor core, and preferably located at the center of the width direction of the outer side of the glue storage tank. The radially extending glue injection hole is connected to the middle of the glue storage tank, and the centerline of the radially extending glue injection hole coincides with the centerline of the glue storage tank. Thus, the position of the glue injection hole 27 is correspondingly located at the geometric center of the glue storage tank 26 and the magnet slot, that is, at the center of the width and length directions of both the glue storage tank 26 and the magnet slot, which is beneficial for the glue to flow and disperse evenly in all directions during glue injection.

[0039] The embedded rotor structure of the permanent magnet motor of the present invention can be used in a fractional-slot concentrated winding permanent magnet synchronous motor. The stator segmented iron core is automatically wound on a winding machine, and multiple wound segmented winding iron cores 22 are spliced ​​together to form the stator. The rotor iron core 21 is formed by stacking multiple rotor laminations. After being heated and expanded, the rotor iron core 21 is fitted onto the rotating shaft 25. The rotor iron core 21 is provided with magnet slots. When installing the magnets 24, the unmagnetized magnets 24 are first inserted into the magnet slots, and then the nozzle of the glue gun 28 is inserted into the radial cylindrical glue injection hole 27 of the rotor iron core 21 (e.g., Figure 6 As shown), gently squeeze the glue gun 28 to fill the entire gap of the magnet slot with glue.

[0040] This invention also discloses a glue-injection manufacturing process for permanent magnet motors that differs from existing processes. Unlike existing processes, the assembly method of the permanent magnet motor of this invention, especially its glue-injection manufacturing process, is applicable to permanent magnet motors with the structure of this invention. In the glue-injection process, the un-glued magnets are first installed into the magnet slots of the rotor core. Then, glue is injected into the glue storage tank through the glue injection hole, so that the glue is evenly distributed between the magnets and the magnet slots, and between the magnets and the glue storage tank, thereby ensuring a firm bond between the magnets. This differs from the existing technology of first applying glue to the magnets and then installing the glued magnets into the magnet slots. This glue-injection process of this invention has more advantages. First, the existing technology of applying glue first and then installing the magnets will lose some glue. Second, because no glue is applied when installing the magnets, the preset force acting on the magnets can be kept basically unchanged. In contrast, in the existing technology, because glue is applied first, the preset force is reduced due to the presence of glue, ultimately failing to meet the requirements for the preset force.

[0041] The permanent magnet motor with an embedded rotor structure of the present invention adds an injection hole 27 to the outside of the rotor core 21 to facilitate the injection of glue into the magnet slot by the glue gun 28; and sets a glue storage tank 26 on the magnet slot of the rotor core 21 to increase the reliability of glue bonding and prevent the magnet 24 from falling off when the motor rotates at high speed; at the same time, it also increases the back electromotive force of the motor and reduces the motor loss.

[0042] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A permanent magnet motor with an embedded rotor structure, characterized in that, It includes a stator core and a rotor core. The rotor core is provided with a magnet slot for accommodating magnets. A glue storage slot is provided on the side of the magnet slot near the outer ring of the rotor core. The width of the glue storage tank is smaller than the width of the magnet tank; The outer wall of the rotor core is provided with a glue injection hole corresponding to the glue storage tank, and the glue injection hole is connected to the corresponding glue storage tank. The injection hole extends radially along the rotor core; The glue injection hole is located at the center of the outer side of the glue storage tank, and the glue injection hole is connected to the middle of the glue storage tank; The interior of the glue storage tank has a hollow square or frustum-shaped cavity, while the upper and lower end punches do not have cuts, and the end punches cover the hollow square or frustum-shaped cavity. The injection hole is positioned at the center of both the glue storage tank and the magnetic steel tank in the width and length directions.

2. The permanent magnet motor with an embedded rotor structure according to claim 1, characterized in that, The glue storage tank is a square tank or a conical tank.

3. The permanent magnet motor with an embedded rotor structure according to claim 1, characterized in that, The glue storage tank is located in the middle of one end of the magnetic steel tank, and the centerline of the glue storage tank coincides with the centerline of the magnetic steel tank.

4. The permanent magnet motor with an embedded rotor structure according to any one of claims 1-3, characterized in that, The length-to-width ratio of the glue storage tank is 11-13:

1.

5. The permanent magnet motor with an embedded rotor structure according to claim 4, characterized in that, The length to width ratio of the glue storage tank is 12:

1.

6. An assembly method for a permanent magnet motor with an embedded rotor structure according to any one of claims 1-5, characterized in that, Includes the following steps: First, the uncoated magnets are installed into the magnet slots of the rotor core, and then glue is injected into the glue storage tank through the glue injection hole on the outer wall of the rotor core.

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