CN116420299A - Brushless motor - Google Patents
Brushless motor Download PDFInfo
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- CN116420299A CN116420299A CN202180075272.6A CN202180075272A CN116420299A CN 116420299 A CN116420299 A CN 116420299A CN 202180075272 A CN202180075272 A CN 202180075272A CN 116420299 A CN116420299 A CN 116420299A
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- circuit board
- brushless motor
- dielectric
- silicone gel
- plate
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
- H02K11/02—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for suppression of electromagnetic interference
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
- H02K11/30—Structural association with control circuits or drive circuits
- H02K11/33—Drive circuits, e.g. power electronics
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
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- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
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- Inverter Devices (AREA)
Abstract
The noise reduction structure of the brushless motor comprises: a circuit board having a switching element and an electrolytic capacitor mounted on a first surface; a conductive member that faces a second surface of the circuit board on the opposite side of the first surface; a conductive connection portion that connects a conductive pattern formed on a circuit board and connected to a cathode terminal of an electrolytic capacitor, to a conductive member; and a dielectric material interposed between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically coupled to the switching element.
Description
Technical Field
The present disclosure relates to a brushless motor.
Background
In general, a brushless motor requires less electromagnetic noise flowing out to the outside of the brushless motor. Accordingly, a brushless motor having a structure that suppresses outflow of electromagnetic noise to the outside of the brushless motor has been proposed.
For example, in order to suppress electromagnetic noise generated from a stator from flowing out to the outside of a brushless motor, the brushless motor described in patent document 1 includes: a first ground path through the rotor housing, shaft, bearing holder portion, and conductive portion; and a second ground path through the rotor housing, shaft, bearing and conductive portion.
According to this brushless motor, even when electromagnetic noise is generated from the stator, the electric potential induced in the rotor and the shaft can be effectively guided to the ground portion of the circuit board, and therefore the EMC (Electro magnetic Compatibility: electromagnetic compatibility) performance of the brushless motor can be improved.
Prior art literature
Patent literature
Patent document 1: japanese patent No. 6648619
Disclosure of Invention
Technical problem to be solved by the invention
In general, a switching element for driving a stator is mounted on a circuit board of a brushless motor. The switching element is known to generate electromagnetic noise at the time of switching operation. Therefore, in order to improve EMC performance of the brushless motor, it is desirable to suppress outflow of electromagnetic noise generated from the switching element to the outside of the brushless motor.
The present disclosure has been made in view of the above-described problems, and an object thereof is to provide a brushless motor capable of suppressing electromagnetic noise generated from a switching element from flowing out to the outside of the brushless motor.
Technical proposal adopted for solving the technical problems
In order to achieve the above object, a brushless motor according to one embodiment of the present disclosure is a brushless motor including a noise reduction structure that reduces electromagnetic noise, the noise reduction structure including: a circuit board having a switching element and an electrolytic capacitor mounted on a first surface; a conductive member facing a second surface of the circuit board opposite to the first surface; a conductive connection portion that connects a conductive pattern formed on the circuit board and connected to a cathode terminal of the electrolytic capacitor, to the conductive member; and a dielectric material interposed between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically coupled to the switching element.
According to this brushless motor, the outflow of electromagnetic noise generated from the switching element to the outside of the brushless motor can be suppressed.
Drawings
Fig. 1 is a longitudinal sectional view of a brushless motor of an embodiment of the present disclosure.
Fig. 2 is a cross-sectional view schematically showing a noise reduction structure of the brushless motor shown in fig. 1.
Fig. 3 is a view of the circuit board shown in fig. 1 from the arrow A2 side in fig. 1.
Fig. 4 is a view of the plate-like portion of the center piece shown in fig. 1 from the arrow A2 side of fig. 1.
Fig. 5 is an equivalent circuit diagram of the brushless motor shown in fig. 1.
Fig. 6 is a diagram showing a modification of the noise reduction structure shown in fig. 2.
Fig. 7 is a view of the plate-like portion of the center piece of the modification shown in fig. 6 from the arrow A2 side in fig. 1.
Detailed Description
An embodiment of the present disclosure will be described below with reference to the drawings.
Fig. 1 is a longitudinal sectional view of a brushless motor 10 according to an embodiment of the present disclosure. As shown in fig. 1, a brushless motor 10 of an embodiment of the present disclosure includes a rotor 12, a stator 14, a shaft 16, a centerpiece 18, a circuit substrate 20, a substrate housing 22, and a connector member 24.
Arrow A1 represents one axial side of the brushless motor 10, and arrow A2 represents the other axial side of the brushless motor 10. The axial direction of the rotor 12 and the stator 14 described later coincides with the axial direction of the brushless motor 10.
The rotor 12 has a rotor housing 26 and rotor magnets 28. The rotor case 26 is formed in a top cylindrical shape, and a cylindrical bearing housing portion 30 (inner cylindrical portion) is formed in a central portion of a top wall portion of the rotor case 26. The bearing housing portion 30 is located radially inward of the outer cylindrical portion of the rotor case 26. The bearing housing portion 30 houses a pair of bearings 32, and the rotor 12 is rotatably supported by the shaft 16 via the pair of bearings 32.
The rotor magnet 28 is fixed to the inner peripheral surface of the outer cylindrical portion of the rotor case 26. The rotor case 26 is provided in a ring shape along the circumferential direction of the rotor 12, and has N poles and S poles alternately in the circumferential direction of the rotor 12. The brushless motor 10 is of a so-called outer rotor type, and the rotor magnet 28 is disposed to face the stator 14 radially outside the stator 14 described later.
The stator 14 is housed inside the rotor case 26. The stator 14 is formed in an annular shape as a whole and is disposed coaxially with the shaft 16. The bearing housing 30 and the shaft 16 are disposed inside the stator 14.
The stator 14 has a stator core 34, an insulator 36, and a plurality of windings 38. A plurality of pole teeth 40 extending radially around the shaft 16 are formed in the stator core 34, and a plurality of windings 38 are wound around the plurality of pole teeth 40 via an insulator 36.
The center piece 18 is made of metal such as iron or aluminum. The center piece 18 has a plate-like portion 42. The plate-like portion 42 is disposed on the other axial side of the rotor 12 and the stator 14, and faces the opening 44 of the rotor case 26. The stator 14 is fixed to the plate-like portion 42 by a set screw or the like, and thereby the stator 14 is held by the plate-like portion 42.
A shaft support portion 46 is formed in a central portion of the plate-like portion 42. The shaft support portion 46 is formed in a concave shape that opens to the stator 14 side. The shaft 16 is fixed to the shaft support portion 46 in an inserted state, whereby the shaft 16 is supported by the shaft support portion 46.
The circuit board 20 has a control circuit 48 that drives the stator 14. The control circuit 48 includes a plurality of switching elements 50, a plurality of electrolytic capacitors 52, and other electrical components, which will be described later. Fig. 1 shows a part of a plurality of switching elements 50. In addition, fig. 1 shows one of a plurality of electrolytic capacitors 52.
The circuit board 20 is disposed opposite the plate-like portion 42 on the opposite side of the plate-like portion 42 from the rotor 12. The circuit board 20 is provided along the plate-like portion 42. The circuit board 20 is fixed to the plate-like portion 42 by screws 54 or the like.
The substrate case 22 is made of metal such as iron or aluminum. The substrate case 22 is fixed to the plate-like portion 42 from the side opposite to the rotor 12. A circuit board 20 is accommodated inside the board case 22.
The connector member 24 has a connector housing 56 and connector terminals 58. The connector housing 56 is made of resin and is fixed to the plate-like portion 42 by a set screw or the like. The connector terminals 58 are disposed inside the connector housing 56. The connector terminals 58 are electrically connected to the control circuit 48 formed on the circuit board 20.
In the brushless motor 10, the stator 14 forms a rotating magnetic field by switching the current flowing through the plurality of windings 38 by the switching operation of the plurality of switching elements 50. When the stator 14 forms a rotating magnetic field, attractive force and repulsive force are generated between the stator 14 and the rotor magnet 28, and thus the rotor 12 rotates.
However, the plurality of switching elements 50 generate electromagnetic noise at the time of switching operation. Therefore, in order to improve EMC performance of the brushless motor 10, it is desirable to suppress outflow of electromagnetic noise generated from the plurality of switching elements 50 to the outside of the brushless motor 10. Accordingly, the brushless motor 10 includes the noise reduction structure 60 that reduces electromagnetic noise.
Fig. 2 is a cross-sectional view schematically showing a noise reduction structure 60 of the brushless motor 10 shown in fig. 1. As shown in fig. 2, the noise reduction structure 60 has a conductive connection portion 62, a first silicone gel 64, and a second silicone gel 66 in addition to the above-described circuit substrate 20 and plate-like portion 42.
The plate-like portion 42 is an example of a "conductive member", the first silicone gel 64 is an example of a "dielectric" and a "first dielectric", and the second silicone gel 66 is an example of a "second dielectric".
The circuit substrate 20 has a first face 20A and a second face 20B. The first surface 20A is a surface on one side in the board thickness direction of the circuit board 20, and is a surface on the opposite side to the plate-like portion 42. The second surface 20B is a surface on the other side in the board thickness direction of the circuit board 20, and is a surface on one side of the plate-like portion 42.
A plurality of switching elements 50, a plurality of electrolytic capacitors 52, and other electrical components are mounted on the first surface 20A. Fig. 2 shows one of a plurality of switching elements 50. Likewise, fig. 2 shows one of a plurality of electrolytic capacitors 52.
The plurality of electrolytic capacitors 52 have an anode terminal 52A and a cathode terminal 52B, respectively. A conductive pattern 68 connected to the cathode terminals 52B of the plurality of electrolytic capacitors 52 is formed on the first surface 20A of the circuit board 20. In fig. 1, the conductive pattern 68 is indicated by an imaginary line (two-dot chain line).
The plate-like portion 42 faces the second surface 20B of the circuit board 20. A boss portion 70 protruding toward the circuit board 20 is formed on the plate-like portion 42. The boss 70 has a threaded bore 72. The screw hole 72 is formed along the axial direction of the boss 70 and opens to the circuit board 20 side.
The conductive connection portion 62 has the screw 54 and the through hole 74 described above. The screw 54 and the through hole 74 are made of metal, and have conductivity. The through hole 74 is formed in the circuit board 20 and penetrates in the board thickness direction of the circuit board 20.
The inner peripheral surface of the through hole 74 and the opening peripheral portions on both axial sides of the through hole 74 are formed of plating layers, and are electrically connected to each other. The through hole 74 is located coaxially with the boss 70. A screw 54 is inserted into the through hole 74, and the tip end of the screw 54 is screwed into the screw hole 72 of the boss 70.
The conductive pattern 68 and the plate-like portion 42 are electrically connected by the conductive connection portion 62 having the through hole 74 and the screw 54. That is, the conductive pattern 68 is connected to the opening peripheral portion on one side in the axial direction of the through hole 74, and the opening peripheral portion on the other side in the axial direction of the through hole 74 is in contact with the top surface of the boss portion 70. The head of the screw 54 is in contact with the opening peripheral portion on one side in the axial direction of the through hole 74, and the tip of the screw 54 is in contact with the inner peripheral surface of the screw hole 72.
A plurality of signal lines 76 are connected to the circuit board 20. The plurality of signal lines 76 are connected to the conductive patterns 68 of the circuit board 20 via the connector terminals 58 (see fig. 1) of the connector member 24.
The first silicone gel 64 and the second silicone gel 66 are formed of silicone gels, respectively. The first silicone gel 64 is sandwiched between the circuit board 20 and the plate-like portion 42 in a state of being in contact with the circuit board 20 and the plate-like portion 42. Similarly, the second silicone gel 66 is sandwiched between the circuit board 20 and the plate-like portion 42 in a state of being in contact with the circuit board 20 and the plate-like portion 42.
As will be described later, the first silicone gel 64 is disposed at a position corresponding to each of the plurality of switching elements 50, and the second silicone gel 66 is disposed at a position corresponding to each of the plurality of electrolytic capacitors 52.
Fig. 3 is a view of the circuit board 20 shown in fig. 1 from the arrow A2 side in fig. 1. As shown in fig. 3, a plurality of switching elements 50 and a plurality of electrolytic capacitors 52 are distributed on the first surface 20A of the circuit board 20.
Hereinafter, when the plurality of switching elements 50 are distinguished, the plurality of switching elements 50 are referred to as switching elements 50-1 to 50-6, respectively. The plurality of electrolytic capacitors 52 have an anode terminal 52A and a cathode terminal 52B, respectively.
Fig. 4 is a view of the plate-like portion 42 of the center piece 18 shown in fig. 1 from the arrow A2 side of fig. 1. Fig. 4 shows a state in which the first silicone gel 64 and the second silicone gel 66 are coated on the surface of the plate-like portion 42 on the side of the circuit substrate 20.
In fig. 4, the circuit board 20, the plurality of switching elements 50, and the plurality of electrolytic capacitors 52 when the circuit board 20 is assembled to the plate-like portion 42 are shown by phantom lines (two-dot chain lines).
The circuit board 20 is assembled to the plate-like portion 42 in a state in which the first silicone gel 64 and the second silicone gel 66 are coated on the surface of the plate-like portion 42 on the circuit board 20 side, and thereby the first silicone gel 64 and the second silicone gel 66 are sandwiched between the circuit board 20 and the plate-like portion 42 in a state of being in contact with the circuit board 20 and the plate-like portion 42.
As an example, the noise reduction structure 60 includes the first silicone gel 64 disposed at three positions corresponding to the distribution of the plurality of switching elements 50. Hereinafter, when the first silicone gel 64 disposed at these three positions is distinguished, the first silicone gel 64 disposed at these three positions will be referred to as first silicone gels 64-1 to 64-3, respectively.
The first silicone gel 64-1 and the first silicone gel 64-2 are integrally formed with the second silicone gel 66. As an example, the first silicone gel 64-1 is formed continuously with one end of the second silicone gel 66, and the first silicone gel 64-2 is formed continuously with the other end of the second silicone gel 66.
The first silicone gel 64-1, 64-2 and the second silicone gel 66 are each formed in a linear shape. The first silicone gel 64-3 is independent of the first silicone gel 64-1, 64-2 and the second silicone gel 66, and is formed in a linear shape.
The first silicone gel 64-1 is disposed at a position electrostatically bonded to each of the plurality of switching elements 50-1, 50-2. Specifically, a part of the first silicone gel 64-1 is arranged at a position overlapping each of the plurality of switching elements 50-1, 50-2 when the circuit board 20 is seen in plan view. The planar view of the circuit board 20 corresponds to the view of the circuit board 20 from the arrow A2 side in fig. 1.
The first silicone gel 64-2 is disposed at a position electrostatically bonded to each of the plurality of switching elements 50-3 to 50-5. Specifically, a part of the first silicone gel 64-2 is arranged at a position overlapping each of the plurality of switching elements 50-3 to 50-5 when the circuit board 20 is seen in plan view.
The first silicone gel 64-3 is disposed at a position electrostatically bonded to the plurality of switching elements 50-6. Specifically, a part of the first silicone gel 64-3 is disposed at a position overlapping the plurality of switching elements 50-6 when the circuit board 20 is viewed in plan.
As an example, the first silicone gels 64-1 to 64-3 are disposed at positions overlapping with a part of each of the plurality of switching elements 50-1 to 50-6, respectively, but the first silicone gels 64-1 to 64-3 may be disposed at positions overlapping with all of each of the plurality of switching elements 50-1 to 50-6, respectively.
The second silicone gel 66 is disposed at a position electrostatically bonded to each of the plurality of electrolytic capacitors 52. Specifically, a part of the second silicone gel 66 overlaps each of the cathode terminals 52B of the plurality of electrolytic capacitors 52 in a plan view of the circuit board 20, and all of the second silicone gel is disposed at a position not overlapping the anode terminals 52A of the plurality of electrolytic capacitors 52 in a plan view of the circuit board 20.
As an example, the plurality of electrolytic capacitors 52 are arranged in a row and are arranged in the same direction. The cathode terminals 52B of the plurality of electrolytic capacitors 52 are located on the opposite side of the plurality of switching elements 50 from the anode terminals 52A of the plurality of electrolytic capacitors 52.
That is, when the virtual line L1 passing through the anode terminals 52A of the plurality of electrolytic capacitors 52 is set in a plan view of the circuit board 20, the cathode terminals 52B of the plurality of electrolytic capacitors 52 are positioned on one side B1 of the virtual line L1, and the plurality of switching elements 50 are positioned on the other side B2 of the virtual line L1.
As an example, the circuit board 20 is fixed to the plate-like portion 42 by a plurality of screws 54. Hereinafter, when the plurality of screws 54 are distinguished, the plurality of screws 54 will be referred to as screws 54-1 to 54-3, respectively.
The screws 54-1 and 54-2 of the screws 54-1 to 54-3 form the conductive connection portion 62, and the screws 54-1 and 54-2 are connected to the cathode terminals 52B of the plurality of electrolytic capacitors 52 through conductive patterns (corresponding to the conductive patterns 68 shown in fig. 2) not shown. Hereinafter, the conductive connection portions 62 corresponding to the screws 54-1 and 54-2 are sometimes referred to as conductive connection portions 62-1 and 62-2.
The second silicone gel 66 is disposed between the first silicone gels 64-1 to 64-3 and the conductive connecting portions 62-1 and 62-2. That is, when the circuit board 20 is viewed in plan, the conductive connection portions 62-1 and 62-2 are located on one side B1 of the linearly extending second silicone gel 66, and the first silicone gels 64-1 to 64-3 are located on the other side B2 of the second silicone gel 66.
As shown in fig. 2, according to the above-described structure, the noise reduction structure 60 includes a first noise propagation path 78 and a second noise propagation path 80.
In the first noise propagation path 78, electromagnetic noise of the plurality of switching elements 50 propagates from the plurality of switching elements 50 to the cathode terminals 52B of the plurality of electrolytic capacitors 52 via the first silicone gel 64, the plate-like portion 42, the conductive connection portion 62, and the conductive pattern 68.
In the second noise propagation path 80, electromagnetic noise of the plurality of switching elements 50 propagates from the plurality of switching elements 50 to the cathode terminals 52B of the plurality of electrolytic capacitors 52 via the first silicone gel 64, the plate-like portion 42, and the second silicone gel 66.
Fig. 5 is an equivalent circuit diagram of the brushless motor 10 shown in fig. 1. The inverter circuit 82 is formed of a plurality of switching elements 50 (see fig. 3 and 4).
In the noise reduction structure 60, at least a part of the second silicone gel 66 overlaps the cathode terminals 52B of the plurality of electrolytic capacitors 52 when the circuit board 20 is viewed in plan, and all of the second silicone gel 66 does not overlap the anode terminals 52A of the plurality of electrolytic capacitors 52 when the circuit board 20 is viewed in plan, whereby the second silicone gel 66 and the plurality of electrolytic capacitors 52 are electrostatically bonded. That is, the second silicone gel 66 as a dielectric is connected between the plate-like portion 42 and the conductive pattern 68 on the cathode side to which the cathode terminals 52B of the plurality of electrolytic capacitors 52 are connected.
In addition, when at least a part of the second silicone gel 66 overlaps the anode terminals 52A of the plurality of electrolytic capacitors 52 in a plan view of the circuit board 20, and when all of the second silicone gel 66 does not overlap the cathode terminals 52B of the plurality of electrolytic capacitors 52 in a plan view of the circuit board 20, the second silicone gel 66 is not electrostatically bonded to the plurality of electrolytic capacitors 52 as shown by a phantom line (two-dot chain line) in fig. 5. That is, in this case, the second silicone gel 66 is connected between the plate-like portion 42 and the conductive pattern 84 on the anode side to which the anode terminals 52A of the plurality of electrolytic capacitors 52 are connected.
Next, the operation and effect of an embodiment of the present disclosure will be described.
As described in detail above, the brushless motor 10 of an embodiment of the present disclosure includes the noise reduction structure 60 that reduces electromagnetic noise. In the noise reduction structure 60, as shown in fig. 2, a conductive pattern 68 formed on the circuit board 20 is connected to the cathode terminals 52B of the plurality of electrolytic capacitors 52, and the conductive pattern 68 and the plate-like portion 42 are connected by a conductive connection portion 62. Further, the first silicone gel 64 is interposed between the circuit board 20 and the plate-like portion 42 in a state of being in contact with the circuit board 20 and the plate-like portion 42. The first silicone gel 64 is disposed at a position where it is electrostatically bonded to the plurality of switching elements 50.
Accordingly, by the first silicone gel 64, electromagnetic noise of the plurality of switching elements 50 is propagated from the plurality of switching elements 50 to the first noise propagation path 78 of the cathode terminal 52B of the plurality of electrolytic capacitors 52 via the first silicone gel 64, the plate-like portion 42, the conductive connection portion 62, and the conductive pattern 68. Accordingly, electromagnetic noise generated from the plurality of switching elements 50 can be absorbed by the plurality of electrolytic capacitors 52, and thus, the electromagnetic noise generated from the plurality of switching elements 50 can be suppressed from flowing out to the outside of the brushless motor 10, for example, through the plurality of signal lines 76.
Further, the second silicone gel 66 is interposed between the circuit board 20 and the plate-like portion 42 in a state of being in contact with the circuit board 20 and the plate-like portion 42. The second silicone gel 66 is disposed at a position where it electrostatically bonds to the plurality of electrolytic capacitors 52.
Accordingly, the electromagnetic noise of the plurality of switching elements 50 is propagated from the plurality of switching elements 50 to the second noise propagation path 80 of the cathode terminal 52B of the plurality of electrolytic capacitors 52 via the first silicone gel 64, the plate-like portion 42, and the second silicone gel 66 by the second silicone gel 66 and the first silicone gel 64. Accordingly, electromagnetic noise can be propagated to the plurality of electrolytic capacitors 52 through the second noise propagation path 80 in addition to the first noise propagation path 78, and therefore, compared with a configuration in which electromagnetic noise is propagated to the plurality of electrolytic capacitors 52 through only the first noise propagation path 78, for example, the absorption efficiency of electromagnetic noise in the plurality of electrolytic capacitors 52 can be improved.
A part of the first silicone gel 64 is disposed at a position overlapping the plurality of switching elements 50 when the circuit board 20 is viewed in plan. This enables the first silicone gel 64 to be appropriately electrostatically bonded to the plurality of switching elements 50.
A part of the second silicone gel 66 overlaps the cathode terminals 52B of the plurality of electrolytic capacitors 52 in a plan view of the circuit board 20, and all of the second silicone gel is disposed at a position not overlapping the anode terminals 52A of the plurality of electrolytic capacitors 52 in a plan view of the circuit board 20. This enables the second silicone gel 66 to be appropriately electrostatically bonded to the plurality of electrolytic capacitors 52.
In addition, the second silicone gel 66 is disposed between the first silicone gel 64 and the conductive connection portion 62. Therefore, since the path length of the second noise propagation path 80 is shorter than that of the first noise propagation path 78, the electromagnetic noise absorption efficiency in the plurality of electrolytic capacitors 52 can be improved as compared with, for example, the case where the path length of the second noise propagation path 80 is equal to or longer than that of the first noise propagation path 78.
As shown in fig. 4, the first silicone gel 64-1 is formed in a linear shape, and overlaps the plurality of switching elements 50-1 and 50-2 when the circuit board 20 is viewed in plan, and the first silicone gel 64-2 is formed in a linear shape, and overlaps the plurality of switching elements 50-3 to 50-5 when the circuit board 20 is viewed in plan. Therefore, the coating process of the first silicone gel 64 can be simplified as compared with, for example, the case where the first silicone gel 64 is arranged for each of the plurality of switching elements 50.
The second silicone gel 66 is formed in a linear shape and overlaps the cathode terminals 52B of the plurality of electrolytic capacitors 52 when the circuit board 20 is viewed in plan. Therefore, the coating process of the second silicone gel 66 can be simplified as compared with, for example, the case where the second silicone gel 66 is arranged for each of the plurality of electrolytic capacitors 52.
In addition, the noise reduction structure 60 uses the plate-like portion 42 of the center piece 18 as a conductive member that propagates electromagnetic noise. Therefore, for example, the structure of the noise reduction structure 60 can be simplified as compared with the case of using a dedicated conductive member that propagates electromagnetic noise.
Next, a modification of an embodiment of the present disclosure will be described.
Fig. 6 is a diagram showing a modification of the noise reduction structure 60 shown in fig. 2, and fig. 7 is a view of the plate-like portion 42 of the center piece 18 in the modification shown in fig. 6 from the arrow A2 side in fig. 1. In the above embodiment, as a preferable example, the first silicone gel 64 and the second silicone gel 66 are used. However, for example, in the case where the first silicone gel 64 is sufficient, as shown in fig. 6, 7, the second silicone gel 66 (see fig. 2, 4) may also be omitted.
In the above embodiment, the cathode terminals 52B of the plurality of electrolytic capacitors 52 are located on the opposite side of the plurality of switching elements 50 from the anode terminals 52A of the plurality of electrolytic capacitors 52, but the cathode terminals 52B of the plurality of electrolytic capacitors 52 may be located on the side of the plurality of switching elements 50 from the anode terminals 52A of the plurality of electrolytic capacitors 52.
With this configuration, for example, the distance between the cathode terminal 52B of the plurality of electrolytic capacitors 52 and the plurality of switching elements 50 becomes shorter than in the case where the cathode terminal 52B of the plurality of electrolytic capacitors 52 is located on the opposite side of the anode terminal 52A of the plurality of electrolytic capacitors 52 from the plurality of switching elements 50 (see fig. 4). As a result, the length of the second noise propagation path 80 shown in fig. 2 becomes short, and therefore electromagnetic noise can be efficiently propagated to the plurality of electrolytic capacitors 52 through the second noise propagation path 80.
In the above embodiment, the noise reduction structure 60 is a structure including the plate-like portion 42 of the center piece 18, but may be a structure including the substrate case 22 instead of the plate-like portion 42. In this case, the substrate case 22 corresponds to an example of the "conductive member".
In the above embodiment, the first silicone gel 64 and the second silicone gel 66 are used as examples of the "first dielectric" and the "second dielectric", but the first dielectric and the second dielectric other than the silicone gel may be used. As an example of the "first dielectric material" and the "second dielectric material", the first dielectric material and the second dielectric material may be used as dielectric grease.
In the above embodiment, the arrangement of the plurality of switching elements 50 and the plurality of electrolytic capacitors 52 is an example, and other cases may be used. The arrangement and shape of the first silicone gel 64 and the second silicone gel 66 are examples, and may be other than those described above.
In the above embodiment, a part of the first silicone gel 64 is arranged at a position overlapping each of the plurality of switching elements 50 when the circuit board 20 is seen in plan view, but for example, a plurality of first silicone gels 64 may be used, and each of the plurality of first silicone gels 64 overlaps each of the plurality of switching elements 50 when the circuit board 20 is seen in plan view.
In the above embodiment, a part of the second silicone gel 66 is arranged at a position overlapping each of the plurality of electrolytic capacitors 52 when the circuit board 20 is seen in plan view, but for example, a plurality of second silicone gels 66 may be used, and each of the plurality of second silicone gels 66 overlaps each of the plurality of electrolytic capacitors 52 when the circuit board 20 is seen in plan view.
In the above-described embodiment, the first silicone gel 64 is provided corresponding to all the switching elements 50 mounted on the circuit board 20 as a preferable example, but the first silicone gel 64 may be provided corresponding to only a part of all the switching elements 50 mounted on the circuit board 20.
In the above embodiment, the second silicone gel 66 is provided corresponding to all the electrolytic capacitors 52 mounted on the circuit board 20 as a preferable example, but the second silicone gel 66 may be provided corresponding to only a part of all the electrolytic capacitors 52 mounted on the circuit board 20.
In the above embodiment, the screw 54 and the through hole 74 are used as an example of the "conductive connection portion", but a structure other than the screw 54 and the through hole 74 may be used.
While the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above, and various modifications may be made and implemented without departing from the scope of the present disclosure.
In addition, the entire disclosure of Japanese patent application 2020-186784 is incorporated herein by reference.
All documents, patent applications and technical standards described in the present specification are incorporated in the present specification by reference to the same extent as if each document, patent application and technical standard was specifically and individually described.
With respect to an embodiment of the present disclosure described above, the following supplementary notes are further disclosed.
(additionally, 1)
A brushless motor comprising a noise reduction structure that reduces electromagnetic noise, wherein,
the noise reduction structure includes:
a circuit board having a switching element and an electrolytic capacitor mounted on a first surface;
a conductive member facing a second surface of the circuit board opposite to the first surface;
a conductive connection portion that connects a conductive pattern formed on the circuit board and connected to a cathode terminal of the electrolytic capacitor, to the conductive member; and
and a dielectric material interposed between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically coupled to the switching element.
(additionally remembered 2)
The brushless motor according to supplementary note 1, wherein at least a part of the dielectric is disposed at a position overlapping the switching element in a plan view of the circuit board.
(additionally, the recording 3)
The brushless motor according to any one of supplementary notes 1 and 2, wherein,
the noise reduction structure includes:
a first dielectric as the dielectric; and
and a second dielectric member interposed between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically coupled to the electrolytic capacitor.
(additionally remembered 4)
The brushless motor according to item 3, wherein at least a part of the second dielectric overlaps the cathode terminal of the electrolytic capacitor in a plan view of the circuit board, and all of the second dielectric is disposed at a position not overlapping the anode terminal of the electrolytic capacitor in a plan view of the circuit board.
(additionally noted 5)
The brushless motor according to any one of supplementary notes 3 and 4, wherein the second dielectric is disposed between the first dielectric and the conductive connecting portion.
(additionally described 6)
The brushless motor according to any one of supplementary notes 3 to 5, wherein,
a plurality of switching elements are mounted on the first surface of the circuit board,
the first dielectric is formed in a linear shape and overlaps the plurality of switching elements when the circuit board is viewed in plan.
(additionally noted 7)
The brushless motor according to any one of supplementary notes 3 to 6, wherein,
a plurality of electrolytic capacitors are mounted on the first surface of the circuit board,
the second dielectric is formed in a linear shape and overlaps with the cathode terminals of the plurality of electrolytic capacitors in a plan view of the circuit board.
(additionally noted 8)
The brushless motor according to any one of supplementary notes 3 to 7, wherein the first dielectric and the second dielectric are integrally formed.
(additionally, the mark 9)
The brushless motor according to any one of supplementary notes 3 to 8, wherein the first dielectric and the second dielectric are silicone gel.
(additionally noted 10)
The brushless motor according to any one of supplementary notes 1 to 9, wherein a cathode terminal of the electrolytic capacitor is located on a side opposite to the switching element with respect to an anode terminal of the electrolytic capacitor.
(additionally noted 11)
The brushless motor according to any one of supplementary notes 1 to 10, wherein a cathode terminal of the electrolytic capacitor is positioned on the switching element side with respect to an anode terminal of the electrolytic capacitor.
(additional recording 12)
The brushless motor according to any one of supplementary notes 1 to 11, wherein,
the brushless motor includes:
a rotor having a rotor case with a top cylindrical shape;
a stator that is housed inside the rotor case; and
a center member having a plate-like portion opposed to the opening of the rotor case and holding the stator,
the circuit board is disposed opposite to the plate-like portion on the opposite side of the rotor from the plate-like portion,
the conductive member is the plate-like portion.
(additional recording 13)
The brushless motor according to any one of supplementary notes 1 to 11, wherein,
the brushless motor includes:
a rotor having a rotor case with a top cylindrical shape;
a stator that is housed inside the rotor case; and
a center member having a plate-like portion opposed to the opening of the rotor case and holding the stator,
the circuit board is disposed opposite to the plate-like portion on the opposite side of the rotor from the plate-like portion,
the conductive member is a substrate case for accommodating the circuit substrate.
Claims (8)
1. A brushless motor includes a noise reduction structure that reduces electromagnetic noise,
the noise reduction structure has:
a circuit board having a switching element and an electrolytic capacitor mounted on a first surface;
a conductive member that is opposed to a second surface of the circuit substrate on a side opposite to the first surface;
a conductive connection portion that connects a conductive pattern formed on the circuit substrate and connected to a cathode terminal of the electrolytic capacitor with the conductive member; and
and a dielectric material interposed between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically coupled to the switching element.
2. The brushless motor of claim 1 wherein,
at least a part of the dielectric is disposed at a position overlapping the switching element in a plan view of the circuit board.
3. A brushless motor as claimed in claim 1 or 2, wherein,
the noise reduction structure has:
a first dielectric as the dielectric; and
and a second dielectric material interposed between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically coupled to the electrolytic capacitor.
4. The brushless motor of claim 3 wherein,
at least a part of the second dielectric overlaps with the cathode terminal of the electrolytic capacitor in a plan view of the circuit board, and all of the second dielectric is arranged at a position not overlapping with the anode terminal of the electrolytic capacitor in a plan view of the circuit board.
5. The brushless motor as claimed in claim 3 or 4, wherein,
the second dielectric is disposed between the first dielectric and the conductive connection.
6. The brushless motor according to any one of claim 3 to 5,
a plurality of the switching elements are mounted on a first surface of the circuit substrate,
the first dielectric is formed in a linear shape and overlaps the plurality of switching elements in a plan view of the circuit board.
7. The brushless motor according to any one of claims 3 to 6,
a plurality of electrolytic capacitors are mounted on the first surface of the circuit substrate,
the second dielectric is formed in a linear shape and overlaps with the cathode terminals of the plurality of electrolytic capacitors in a plan view of the circuit board.
8. The brushless motor according to any one of claims 1 to 7,
the brushless motor includes:
a rotor having a rotor case of a top cylindrical shape;
a stator housed inside the rotor case; and
a center member having a plate-like portion opposed to the opening of the rotor housing and holding the stator,
the circuit board is disposed opposite to the plate-like portion on the opposite side of the plate-like portion from the rotor,
the conductive member is the plate-like portion.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020186784A JP7484670B2 (en) | 2020-11-09 | 2020-11-09 | Brushless motor |
| JP2020-186784 | 2020-11-09 | ||
| PCT/JP2021/029566 WO2022097338A1 (en) | 2020-11-09 | 2021-08-10 | Brushless motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116420299A true CN116420299A (en) | 2023-07-11 |
Family
ID=81457673
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180075272.6A Pending CN116420299A (en) | 2020-11-09 | 2021-08-10 | Brushless motor |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP7484670B2 (en) |
| CN (1) | CN116420299A (en) |
| WO (1) | WO2022097338A1 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012135213A (en) | 2012-04-13 | 2012-07-12 | Mitsubishi Electric Corp | Brushless dc motor and apparatus |
| JP2020072500A (en) | 2018-10-29 | 2020-05-07 | 株式会社デンソー | Rotary electric machine |
-
2020
- 2020-11-09 JP JP2020186784A patent/JP7484670B2/en active Active
-
2021
- 2021-08-10 CN CN202180075272.6A patent/CN116420299A/en active Pending
- 2021-08-10 WO PCT/JP2021/029566 patent/WO2022097338A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| JP2022076387A (en) | 2022-05-19 |
| JP7484670B2 (en) | 2024-05-16 |
| WO2022097338A1 (en) | 2022-05-12 |
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