A permanent magnet motor having a magnetocaloric shunt layer

Abstract

The utility model discloses a permanent magnet motor with magnetic heat shunt layer, including the casing, as the bearing part of permanent magnet structure, the inner wall middle part of casing has the rough surface, and the rough surface is formed by roughening treatment, and the adhesion strength can be improved to increase roughness, permanent magnet structure, install in the inner wall of casing, and the permanent magnet structure includes the magnetic heat shunt layer and the magnetic tile, and the magnetic heat shunt layer is adhered in the upper casing through the adhesive, and because the adhesion strength has increased due to the roughness, the thickness of the adhesive can be reduced, and the magnetic heat shunt layer is used for increasing the magnetic flux and improving the heat dissipation performance, and the magnetic tile is adhered on the exposed surface of the magnetic heat shunt layer through the adhesive, the bonding strength of the adhesive is increased through the rough surface formed on the inner wall of the casing, and the magnetic heat shunt layer is arranged between the casing and the magnetic tile, the heat dissipation performance is increased while the magnetic flux is improved, so that the magnet structure has excellent heat conduction performance and has higher magnetic flux, and the magnetic stability is improved.

Description

Technical Field

[0001] This utility model relates to the field of motors, and is particularly applicable to motors used in automotive actuators, especially to a permanent magnet motor with a magnetothermal shunt layer. Background Technology

[0002] Automotive actuators are core components of automotive electronic control systems, responsible for converting control signals transmitted by the electronic control unit (ECU) into actual mechanical or electrical motion, thereby achieving precise control of key components such as the engine and braking system. Motors used in automotive actuators include, but are not limited to: EPB (Electronic Parking Brake) actuator, ABS modulator pump, ESC / ESP hydraulic control unit motor, HVAC blower / cabin fan, wiper motor (brushed DC motor), seat adjustment / seat rail motor, window lift motor, sunroof motor / trunk opening motor, HVAC damper actuator motor, permanent magnet DC (PMDC) micro motor, rear differential unit (RDU) motor, other permanent magnet DC (PMDC) and brushed DC motors, electric tailgate / trunk opening motor, radiator cooling fan (older models), headlight leveling motor, throttle body actuator, vacuum pump actuator motor (electric / hybrid vehicles), electric bicycle hub motor, remote control model motor (large brushed), permanent magnet DC (PMDC) or other brushed DC motors.

[0003] In current EPB and actuator motor production, magnets are typically bonded to the inner wall of the stator housing using epoxy or silicone-based adhesives. This simple bonding process reduces costs and allows for a compact motor design. However, this design presents the following key challenges: Magnetic leakage: The adhesive layer is a non-magnetic material, increasing the effective air gap and reducing the air gap magnetic flux density; Poor heat dissipation: The adhesive layer has poor thermal conductivity, leading to localized overheating of the magnets during braking cycles. Utility Model Content

[0004] To overcome the shortcomings of existing technologies, this invention provides a permanent magnet motor with a magnetothermal shunt layer, which solves the following technical problems: In current EPB and actuator motor production, magnet tiles are typically bonded to the inner wall of the stator housing using epoxy or silicone-based adhesives. This simple bonding process reduces costs and allows for a compact motor design. However, this design suffers from the following key issues: Magnetic leakage: The adhesive layer is a non-magnetic material, increasing the effective air gap and reducing the air gap magnetic flux density; Poor heat dissipation: The adhesive layer has poor thermal conductivity, leading to localized overheating of the magnet during braking cycles.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a permanent magnet motor with a magnetothermal shunt layer, the permanent magnet motor including a housing as a load-bearing component of the permanent magnet structure, the middle part of the inner wall of the housing having a rough surface, the rough surface being formed by roughening treatment, increasing roughness to improve bonding strength; a permanent magnet structure, installed on the inner wall of the housing, the permanent magnet structure including a magnetothermal shunt layer and magnetic tiles, the magnetothermal shunt layer being bonded to the housing by an adhesive, since the roughness increases the bonding strength, the thickness of the adhesive can be reduced, the magnetothermal shunt layer is used to increase magnetic flux and improve heat dissipation performance, the magnetic tiles being bonded to the exposed surface of the magnetothermal shunt layer by an adhesive; a rear cover structure, the rear cover structure including a plastic end cap and a rear iron cover, bearings being embedded in both the rear iron cover and the housing, the rotor structure being mounted inside the housing by two bearings.

[0006] As a preferred technical solution of this utility model, the magnetothermal shunt layer is made of a soft magnetic shunt layer and a heat dissipation metal foil rolled together, with the soft magnetic shunt layer adjacent to the shell and the heat dissipation metal foil adjacent to the magnetic tile.

[0007] As a preferred technical solution of this utility model, the soft magnetic shunt layer can be low-carbon steel or iron-silicon electrical steel.

[0008] As a preferred embodiment of this invention, the heat dissipation metal foil may be copper foil or aluminum foil.

[0009] As a preferred embodiment of this utility model, a glue groove is formed on the rough surface of the shell, and adhesive is dripped into the inside of the glue groove.

[0010] As a preferred embodiment of this utility model, the adhesive is a high-temperature epoxy resin; As a preferred embodiment of this utility model, the plastic end cap is provided with an insert that can connect to the outside, and a carbon brush is also provided inside the plastic end cap. The rear iron cover is fixedly connected to the housing.

[0011] As a preferred embodiment of the present invention, the rotor structure includes a rotating shaft that passes between two bearings, and a rotor core is fixed to the outside of the rotating shaft. A commutator that cooperates with carbon brushes is provided on the outside of the rotating shaft.

[0012] Compared with the prior art, the beneficial effects that this utility model can achieve are: 1. By increasing the bonding strength of the adhesive through the rough surface formed on the inner wall of the shell, and by setting a magnetothermal shunt layer between the shell and the magnetic tile, the magnetic flux is increased while the heat dissipation performance is also increased, so that the magnet structure has excellent thermal conductivity and high magnetic flux, thus improving magnetic stability. 2. By placing a heat-dissipating metal foil near the magnetic tile, heat transfer can be improved, reducing the working temperature of the magnetic tile. The soft magnetic shunt layer increases the magnetic flux and improves magnetic stability. At the same time, the adhesive is dripped into the adhesive groove on the rough surface and then coated and smoothed, which further increases the bonding strength of the adhesive. Attached Figure Description

[0013] Figure 1 This is an exploded view of the permanent magnet motor of this utility model; Figure 2 This is a schematic cross-sectional view of the permanent magnet motor of this utility model; Figure 3 This is a diagram showing the relative positional distribution of the permanent magnet structure of this utility model; Figure 4 This is a schematic diagram of the internal structure of the housing of this utility model; Figure 5 This is a schematic diagram of the present invention after dispensing adhesive; The components are: 1. Housing; 2. Magnet; 3. Magnetothermal shunt layer; 4. Shaft; 5. Rotor core; 6. Adhesive; 7. Soft magnetic shunt layer; 8. Heat dissipation metal foil; 9. Glue groove; 10. Rough surface; 11. Commutator; 12. Plastic end cap; 13. Bearing; 14. Rear iron cover; 15. Drive structure. Detailed Implementation

[0014] To make the technical means, creative features, and achieved objectives and effects of this utility model easier to understand, the present utility model is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this utility model and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described in the implementation are all within the protection scope of this utility model without creative effort.

[0015] Example Please refer to Figures 1-5As shown, this utility model provides a permanent magnet motor with a magnetothermal shunt layer. The permanent magnet motor of this utility model includes, but is not limited to: EPB (Electronic Parking Brake) actuator, ABS modulator pump, ESC / ESP hydraulic control unit motor, HVAC blower / cabin fan, wiper motor (brushed DC motor), seat adjustment / seat rail motor, window lift motor, sunroof motor / trunk opening motor, HVAC damper actuator motor, permanent magnet DC (PMDC) micro motor, rear differential unit (RDU) motor, other permanent magnet DC (PMDC) and brushed DC motors, electric tailgate / trunk opening motor, radiator cooling fan (older models), headlight leveling motor, throttle body actuator, vacuum pump actuator motor (electric / hybrid vehicles), electric bicycle hub motor, remote control model motor (large brushed), permanent magnet DC (PMDC) or other brushed DC motors; all of the above motors are of the type where the magnet is fixed to the motor housing. The permanent magnet motor includes a housing 1, on the inner wall of which a permanent magnet structure is provided. A plastic end cap 12 is embedded in the open end of the housing 1. The plastic end cap contains a carbon brush structure, capacitors, and other essential motor components. An insert is also provided in the plastic end cap, which can extend to the outside of the permanent magnet motor and connect to the outer wires. A rear iron cover 14 is provided in the open end of the housing 1. The rear iron cover 14 has a groove to allow the insert to pass through. The rear iron cover 14 is fixedly connected to the housing 1, thereby enabling the motor to work stably. A bearing 13 is embedded in the rear iron cover 14 and the housing 1. A rotating shaft 4 is interference-fitted to the bearing 13. A rotor core 5 is fixed on the rotating shaft 4. A copper wire winding is provided on the rotor core 5. The two ends of the copper wire of the copper wire winding are connected to a commutator 11 fixed on the outside of the rotating shaft 4. The commutator 11 can cooperate with the carbon brush structure inside the plastic end cap 12. A drive structure 15 is connected to the rotating shaft 4 located on the outside of the housing 1. The drive structure 15 can be a pulley or gear structure, etc. The inner wall of the shell 1 is roughened by sandblasting, micro-grinding and other roughening processes to form a rough surface 10. Multiple small glue grooves 9 can be formed on the rough surface 10, and adhesive 6 is dripped into the glue grooves 9. The adhesive 6 is then spread evenly to form the first layer of adhesive 6, and the permanent magnet structure is bonded on the adhesive 6. Alternatively, the small glue grooves 9 can be omitted from the rough surface 10, and glue can be directly applied to the rough surface 10 at certain intervals. Thus, strong adhesion of the glue can be achieved through the rough surface 10 and the glue grooves 9. like Figure 2As shown, the permanent magnet structure includes a magnetothermal shunt layer 3 and a magnetic tile 2. The magnetothermal shunt layer 3 includes a soft magnetic shunt layer 7 and a heat dissipation metal foil 8. The soft magnetic shunt layer 7 and the heat dissipation metal foil 8 are formed by rolling. The soft magnetic shunt layer 7 is made of AISI 1010 low carbon steel or iron-silicon electrical steel and is used for magnetic flux recovery, increasing magnetic flux and improving magnetic stability. Its thickness is 0.5-1.0 mm. The heat dissipation metal foil 8 is made of copper foil or aluminum foil and is used to conduct the heat of the magnet to the shell. Its thickness is 0.05-0.1 mm. When using copper foil, the thermal conductivity is better than that of aluminum foil, while aluminum foil is the preferred choice for lightweighting. like Figure 2 As shown, after forming the magnetothermal shunt layer 3, the magnetothermal shunt layer 3 is installed on the flat adhesive 6. During installation, the soft magnetic shunt layer 7 is bonded to the shell 1. A second layer of adhesive 6 is applied to the heat dissipation metal foil 8, and the magnetic tile 2 is bonded to the magnetothermal shunt layer 3. After installation, it is heated and cured in an oven in one stage at a curing temperature of 150±5℃ for 30±5 min. Thus, during the curing process, all layers are bonded simultaneously to form an integrated multi-layer composite structure. In summary, a stable magnet structure is formed, the connection strength between the magnet structure and the shell 1 is increased, the thermal conductivity of the magnet structure is improved, it has a high magnetic flux, and the magnetic stability is enhanced.

[0016] In the above structure, the thickness of the adhesive 6 between the shell 1 and the magnetothermal shunt layer 3 is 0.1-0.15 mm, and the thickness of the adhesive 6 between the magnetothermal shunt layer 3 and the magnetic tile 2 is ≤0.1 mm. The adhesive is high-temperature epoxy resin with a thermal conductivity of ( The shear strength is 0.3-1.5 W / (m·K). The initial permeability is 12-25 MPa; AISI 1010 low carbon steel or iron-silicon electrical steel, with a thickness of 0.5-1.0 mm, has an initial permeability of 12-25 MPa. The value is 2500-5000, and the thermal conductivity is ( The initial permeability of iron-silicon electrical steel is 45-55 W / (m·K). The thermal conductivity is 4000-6000. The thermal conductivity of copper foil is 25-35 W / (m·K); the thickness of the heat dissipation metal foil is 0.05-0.1 mm, the thermal conductivity of copper foil is 380-400 W / (m·K), and the thermal conductivity of aluminum foil is 210-230 W / (m·K). Table 1 Expected Comparison Data ; Based on the above data, the following principles and theories are verified: Table 2 Verification Parameters and Values ; 1. Principle of Magnetothermal Diversion Mechanism (1) Problem Analysis: Magnetic Resistivity of the Adhesive Layer In traditional bonded magnet DC motors, permanent magnets are attached to the inner wall of the housing via an adhesive layer. However, most industrial adhesives (epoxy or silicone-based) are non-magnetic materials, and their relative permeability is:

[0017] Similar to air, the magnetic circuit through the adhesive layer is equivalent to a series air gap, increasing the total magnetic reluctance R: Total magnetic reluctance of a conventional motor:

[0018] in, For the magnetic reluctance of the magnet, For adhesive magnetic resistance;

[0019] The thickness of the adhesive layer is 0.10-0.15 mm. This represents the bonding area.

[0020] Although the adhesive layer is extremely thin, 1 / ( The value is relatively large, therefore It can account for 5% - 10% of the total magnetic circuit reluctance, directly resulting in: magnetic flux leakage to the housing instead of the air gap; and a decrease in the magnetic flux density in the air gap (which in turn leads to a decrease in torque).

[0021] (2) Solution: Parallel magnetic shunt path This invention inserts a soft magnetic shunt plate (made of low-carbon steel or electrical steel) behind the adhesive layer (between the magnet and the housing). This layer provides a low-resistivity parallel alternative path. The magnetic circuit is transformed from a single series path to a parallel magnetic flux path structure. Total magnetic reluctance of the new motor:

[0022]

[0023] in, The thickness of the magnetothermal shunt layer, The area of ​​the magnetocaloric shunt layer, ; because Parallel combination equivalent magnetic reluctance The low-resistance shunt path dominates, that is:

[0024] Therefore, the effective magnetic resistance of the bonding air gap is reduced by more than an order of magnitude.

[0025] 2. Calculation of typical EPB motor geometric parameters Adhesive layer thickness =0.15mm; Magnetothermal shunt layer thickness =0.5mm; Bonding area A=500mm² 2 Vacuum permeability =4π×10 -7 H / m; (1) Calculation of magnetic reluctance of adhesive layer:

[0026] (2) Calculation of magnetic reluctance of flux shunt plate:

[0027] (3) Equivalent magnetic reluctance and reduction ratio

[0028] Effective reluctance reduction ratio:

[0029] (4) Increase in total magnetic reluctance and air gap flux density Assuming that in traditional designs the adhesive layer reluctance accounts for 8% of the total reluctance ( =1.00, =0.08), after the improvement, the magnetic reluctance of this part is reduced by 1500 times, so the total magnetic reluctance of the new motor is:

[0030] Total reluctance reduction rate:

[0031] Magnetic flux ratio:

[0032] in, For the new motor flux, For traditional electric motor magnetic flux; According to the inverse relationship between magnetic flux and magnetic reluctance (Φ = magnetomotive force / magnetic reluctance), the air gap magnetic flux density Bg is directly proportional to the magnetic flux Φ (Bg = ... (where Ag is the air gap area, which is constant), therefore:

[0033] in, The air gap flux density of the new motor, This refers to the air gap magnetic flux density of a traditional electric motor. The air gap magnetic flux density is increased by approximately 8.7% (the actual measured increase is 6%-9%, depending on the shell permeability and magnet grade).

[0034] (5) Physical explanation Magnetothermal shunt plate layer ( (≈4000-6000) provides a low magnetic reluctance bypass around the adhesive layer. Since magnetic reluctance is inversely proportional to permeability μ, a material with a permeability 4000 times that of air or adhesive can significantly reduce the total magnetic reluctance, thus allowing the same magnetomotive force to drive more magnetic flux through the air gap.

[0035] 3. Torque Boost Calculation For brushless motors or DC motors, the torque formula is:

[0036] (where k) t (Φ is the torque constant, which depends on the winding and geometry; Φ is the unipolar flux; I is the armature current) Under constant current, torque is proportional to magnetic flux, that is:

[0037] in, For the new motor torque; This is the torque of a traditional motor; Considering magnetic saturation and resistive losses in actual operating conditions, 80% of the theoretical gain can be achieved, therefore:

[0038] Based on the benchmark EPB motor torque For example, with a value of 1.20 N·m: = 1.20 × 1.0696 = 1.284 N·m = - =1.284-1.20 = 0.084 N·m

[0039] The torque is increased by approximately 7%.

[0040] 4. Calculation of magnet temperature drop The thermal resistance formula is:

[0041] Where t is the thickness, k is the thermal conductivity, and A is the area. (1) Calculation results of thermal resistance of each layer Table 3 Calculation results of thermal resistance for each layer ; (2) Equivalent thermal resistance and temperature rise The adhesive layer and the flow distribution layer are thermally parallel, with an equivalent thermal resistance of:

[0042] in, For the thermal resistance of the magnetocaloric shunt layer, For the thermal resistance of the adhesive; Thermal resistance reduction rate: (0.30-0.0205) / 0.30≈93% Assuming the magnet's heat dissipation power Q = 8 W, then:

[0043]

[0044] Note: The simplified layer model has smaller numerical values. In the actual EPB thermal cycle, the temperature gradient will amplify this temperature difference, and the final magnet temperature can be reduced by 10-15℃.

[0045] 5. Magnetic Energy Verification Magnetic energy density:

[0046] If the magnetic flux density B increases from 0.90 T to 0.98 T (+8.9%), then:

[0047] in, For the magnetic energy density of the new motor, The magnetic energy density of a traditional electric motor; The magnetic energy was increased by 18.6%, which explains the principle that the rotor can generate greater electromagnetic torque under the same excitation.

[0048] Table 4 Performance Comparison Table (I) ; Table 5 Performance Comparison Table (II) ; In summary, the permanent magnet (60mm in length and 3mm in thickness) is bonded to the steel casing (56mm in inner diameter) via a 0.1mm epoxy resin layer. A 0.5mm thick iron-silicon alloy flux shunt plate (initial permeability of 4000 and thermal conductivity of 25 W / (m·K)) is integrated between the magnet and the adhesive. After assembly, under the same load, the torque increases from 1.12 N·m to 1.21 N·m, and the magnet temperature decreases from 142℃ to 128℃.

[0049] In the description of this utility model, it should be understood that the terms "front", "rear", "left", "right", "up", "down", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A permanent magnet motor with a magnetothermal shunt layer, characterized in that: The permanent magnet motor includes The shell (1), as the load-bearing component of the permanent magnet structure, has a rough surface (10) in the middle part of the inner wall of the shell (1). The rough surface (10) is formed by roughening treatment. Increasing the roughness can improve the bonding strength. The permanent magnet structure is installed on the inner wall of the shell (1). The permanent magnet structure includes a magnetothermal shunt layer (3) and a magnetic tile (2). The magnetothermal shunt layer (3) is bonded to the shell (1) (10) by an adhesive (6). Since the roughness increases the bonding strength, the thickness of the adhesive (6) can be reduced. The magnetothermal shunt layer is used to increase the magnetic flux and improve the heat dissipation performance. The magnetic tile (2) is bonded to the exposed surface of the magnetothermal shunt layer (3) by an adhesive (6). The rear cover structure includes a plastic end cap and a rear iron cover. Both the rear iron cover and the housing are inlaid with bearings (13). The rotor structure is mounted inside the housing (1) by the two bearings (13).

2. A permanent magnet motor with a magnetothermal shunt layer according to claim 1, characterized in that: The magnetic thermal shunt layer (3) is rolled and composite of a soft magnetic shunt layer (7) and a heat dissipation metal foil (8). The soft magnetic shunt layer (7) is adjacent to the shell (1), and the heat dissipation metal foil (8) is adjacent to the magnetic tile (2).

3. A permanent magnet motor with a magnetothermal shunt layer according to claim 2, characterized in that: The soft magnetic shunt layer (7) can be made of low-carbon steel.

4. A permanent magnet motor with a magnetothermal shunt layer according to claim 2, characterized in that: The heat dissipation metal foil (8) can be copper foil.

5. A permanent magnet motor with a magnetothermal shunt layer according to claim 1, characterized in that: The shell (1) has a glue groove (9) on its rough surface, and adhesive (6) is dripped into the inside of the glue groove (9).

6. A permanent magnet motor with a magnetothermal shunt layer according to claim 1, characterized in that: The adhesive (6) is a high-temperature epoxy resin.

7. A permanent magnet motor with a magnetothermal shunt layer according to claim 1, characterized in that: The plastic end cap has an insert that can connect to the outside, and a carbon brush is also installed inside the plastic end cap. The rear iron cover is fixedly connected to the housing.

8. A permanent magnet motor with a magnetothermal shunt layer according to claim 7, characterized in that: The rotor structure includes a shaft (4) which passes between two bearings (13), and a rotor core (5) is fixed on the outside of the shaft (4). A commutator (11) that cooperates with a carbon brush is provided on the outside of the shaft (4).

Images