Brushless electric motor

Abstract

The noise reduction structure of the brushless motor has: a circuit substrate, the circuit substrate is provided with a switching element and an electrolytic capacitor on a first surface; a conductive member, the conductive member is opposite to a second surface of the circuit substrate which is opposite to the first surface; a conductive connecting part, the conductive connecting part connects a conductive pattern formed on the circuit substrate and a cathode terminal of the electrolytic capacitor with the conductive member; and a dielectric, the dielectric is arranged between the circuit substrate and the conductive member in a state of contacting the circuit substrate and the conductive member, and is arranged at a position of electrostatically combining with the switching element.

Description

Technical Field

[0001] This disclosure relates to a brushless electric motor. Background Technology

[0002] Generally, brushless motors require minimal electromagnetic noise flowing out of the motor. Therefore, a brushless motor with a structure that suppresses electromagnetic noise flowing out of the motor is proposed.

[0003] For example, in order to suppress the outflow of electromagnetic noise generated from the stator to the outside of the brushless motor, the brushless motor described in Patent Document 1 has: a first grounding path through the rotor housing, shaft, bearing, bearing retainer and conductive part; and a second grounding path through the rotor housing, shaft, bearing and conductive part.

[0004] According to this brushless motor, even when electromagnetic noise is generated from the stator, the potential induced in the rotor and shaft can be effectively guided to the grounding part of the circuit board, thus improving the EMC (Electromagnetic Compatibility) performance of the brushless motor.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 6648619 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] Generally, a switching element that drives the stator is mounted on the circuit board of a brushless motor. It is known that this switching element generates electromagnetic noise during switching operations. Therefore, in order to improve the EMC performance of the brushless motor, it is desirable to suppress the electromagnetic noise generated by the switching element from flowing out of the brushless motor.

[0010] This disclosure is made in view of the above-mentioned technical problems, and in one aspect, its object is to provide a brushless motor capable of suppressing electromagnetic noise generated from switching elements from flowing to the outside of the brushless motor.

[0011] Technical solutions adopted to solve technical problems

[0012] To achieve the above objectives, one aspect of the brushless motor disclosed herein is a brushless motor including a noise reduction structure for reducing electromagnetic noise, wherein the noise reduction structure comprises: a circuit board on which a switching element and an electrolytic capacitor are mounted on a first surface; a conductive member opposite to a second surface of the circuit board opposite to the first surface; a conductive connection portion connecting a conductive pattern formed on the circuit board and connected to the cathode terminal of the electrolytic capacitor to the conductive member; and a dielectric material sandwiched between the circuit board and the conductive member in contact with the circuit board and the conductive member, and disposed at a position electrostatically connected to the switching element.

[0013] According to this brushless motor, it is possible to suppress the outflow of electromagnetic noise generated from the switching element to the outside of the brushless motor. Attached Figure Description

[0014] Figure 1 This is a longitudinal sectional view of a brushless motor according to one embodiment of the present disclosure.

[0015] Figure 2 It is a schematic representation Figure 1 The diagram shows a cross-sectional view of the noise reduction structure of the brushless motor.

[0016] Figure 3 From Figure 1 Observe from the side of arrow A2 Figure 1 The circuit board shown is viewed from the side.

[0017] Figure 4 From Figure 1 Observe from the side of arrow A2 Figure 1 A view of the plate-shaped portion of the central component shown.

[0018] Figure 5 yes Figure 1 The equivalent circuit diagram of the brushless motor is shown.

[0019] Figure 6 It means Figure 2 The diagram shows a modified example of the noise reduction structure.

[0020] Figure 7 From Figure 1 Observe from the side of arrow A2 Figure 6 A view of the plate-like portion of the center member in the modified example shown. Detailed Implementation

[0021] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0022] Figure 1This is a longitudinal sectional view of a brushless motor 10 according to one embodiment of this disclosure. Figure 1 As shown, a brushless motor 10 according to one embodiment of the present disclosure includes a rotor 12, a stator 14, a shaft 16, a center member 18, a circuit board 20, a board housing 22, and a connector member 24.

[0023] Arrow A1 indicates one side of the axial direction of the brushless motor 10, and arrow A2 indicates the other side of the axial direction of the brushless motor 10. The axial directions of the rotor 12 and stator 14, which will be described later, are aligned with the axial direction of the brushless motor 10.

[0024] The rotor 12 has a rotor housing 26 and a rotor magnet 28. The rotor housing 26 is formed into a top cylindrical shape, and a cylindrical bearing housing 30 (inner cylinder portion) is formed in the center of the top wall portion of the rotor housing 26. The bearing housing 30 is located radially inside the outer cylinder portion of the rotor housing 26. A pair of bearings 32 are housed in the bearing housing 30, and the rotor 12 is rotatably supported on the shaft 16 via the pair of bearings 32.

[0025] The rotor magnet 28 is fixed to the inner circumferential surface of the outer cylindrical portion of the rotor housing 26. The rotor housing 26 is annular along the circumference of the rotor 12, and has alternating N and S poles along the circumference of the rotor 12. The brushless motor 10 is a so-called external rotor type, with the rotor magnet 28 arranged radially outward from the stator 14, as described later, opposite to the stator 14.

[0026] The stator 14 is housed inside the rotor housing 26. The stator 14 is integrally formed in an annular shape and is coaxially arranged with the shaft 16. The aforementioned bearing housing 30 and the shaft 16 are arranged inside the stator 14.

[0027] The stator 14 has a stator core 34, an insulator 36, and a plurality of windings 38. A plurality of pole teeth 40 are formed on the stator core 34, extending radially from the shaft 16, and the plurality of windings 38 are wound around the plurality of pole teeth 40 via the insulator 36.

[0028] The center member 18 is made of a metal such as iron or aluminum. The center member 18 has a plate-shaped portion 42. The plate-shaped portion 42 is disposed on the opposite side of the rotor 12 and stator 14 in the axial direction, opposite to the opening 44 of the rotor housing 26. The stator 14 is fixed to the plate-shaped portion 42 by means of locking screws or the like, thereby holding the stator 14 in the plate-shaped portion 42.

[0029] A shaft support portion 46 is formed in the center of the plate-shaped portion 42. The shaft support portion 46 is formed in a concave shape that opens toward the stator 14. The shaft 16 is fixed to the shaft support portion 46 in an inserted state, thereby supporting the shaft 16.

[0030] The circuit board 20 has a control circuit 48 for driving the stator 14. The control circuit 48 includes electrical components such as multiple switching elements 50 and multiple electrolytic capacitors 52, which will be described later. Figure 1 A portion of the multiple switching elements 50 is shown. Additionally, Figure 1 One of a plurality of electrolytic capacitors 52 is shown.

[0031] The circuit board 20 is disposed opposite to the plate-shaped portion 42 on the side opposite to the rotor 12. The circuit board 20 is disposed along the plate-shaped portion 42. The circuit board 20 is fixed to the plate-shaped portion 42 by screws 54 or the like.

[0032] The substrate housing 22 is made of metal such as iron or aluminum. The substrate housing 22 is fixed to the plate-shaped portion 42 from the side opposite to the rotor 12. The circuit board 20 is housed inside the substrate housing 22.

[0033] The connector component 24 has a connector housing 56 and connector terminals 58. The connector housing 56 is made of resin and is fixed to the plate-shaped portion 42 by locking screws or the like. The connector terminals 58 are disposed inside the connector housing 56. The connector terminals 58 are electrically connected to a control circuit 48 formed on the circuit board 20.

[0034] In this brushless motor 10, the current flowing through multiple windings 38 is switched by the switching action of multiple switching elements 50, and the stator 14 forms a rotating magnetic field. When the stator 14 forms a rotating magnetic field, attractive and repulsive forces are generated between the stator 14 and the rotor magnet 28, thereby causing the rotor 12 to rotate.

[0035] However, the multiple switching elements 50 generate electromagnetic noise during switching operations. Therefore, in order to improve the EMC performance of the brushless motor 10, it is desirable to suppress the electromagnetic noise generated from the multiple switching elements 50 from flowing to the outside of the brushless motor 10. Therefore, the brushless motor 10 includes a noise reduction structure 60 to reduce electromagnetic noise.

[0036] Figure 2 It is a schematic representation Figure 1 A cross-sectional view of the noise reduction structure 60 of the brushless motor 10 shown. Figure 2 As shown, in addition to the circuit board 20 and the plate-shaped portion 42, the noise reduction structure 60 also has a conductive connection portion 62, a first silicone gel 64, and a second silicone gel 66.

[0037] The plate-shaped 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".

[0038] The circuit board 20 has a first surface 20A and a second surface 20B. The first surface 20A is a surface of the circuit board 20 on one side in the thickness direction and is located on the side opposite to the plate-shaped portion 42. The second surface 20B is a surface of the circuit board 20 on the other side in the thickness direction and is located on one side of the plate-shaped portion 42.

[0039] Multiple switching elements 50 and multiple electrolytic capacitors 52 and other electrical components are mounted on the first surface 20A. Figure 2 One of a plurality of switching elements 50 is shown. Similarly, Figure 2 One of a plurality of electrolytic capacitors 52 is shown.

[0040] Multiple electrolytic capacitors 52 each have an anode terminal 52A and a cathode terminal 52B. A conductive pattern 68, connecting to the cathode terminals 52B of the multiple electrolytic capacitors 52, is formed on the first surface 20A of the circuit board 20. Figure 1 In the diagram, the conductive pattern 68 is represented by an imaginary line (double-dotted line).

[0041] The plate-shaped portion 42 faces the second surface 20B of the circuit board 20. A bushing portion 70 protruding toward the circuit board 20 is formed on the plate-shaped portion 42. The bushing portion 70 has a threaded hole 72. The threaded hole 72 is formed along the axial direction of the bushing portion 70 and opens toward the circuit board 20.

[0042] The conductive connection portion 62 has the aforementioned screw 54 and through hole 74. Both the screw 54 and the through hole 74 are made of metal and are conductive. The through hole 74 is formed on the circuit board 20 and extends through the circuit board 20 along its thickness direction.

[0043] The inner circumferential surface of the through hole 74 and the peripheral portions of the openings on both axial sides of the through hole 74 are formed by plating and are electrically connected to each other. The through hole 74 is coaxial with the bushing portion 70. A screw 54 is inserted into the inside of the through hole 74, and the front end of the screw 54 is screwed into the threaded hole 72 of the bushing portion 70.

[0044] The conductive pattern 68 and the plate-shaped portion 42 are electrically connected through the conductive connection portion 62 having the through hole 74 and the screw 54. That is, the conductive pattern 68 is connected to the peripheral portion of the opening on one axial side of the through hole 74, and the peripheral portion of the opening on the other axial side of the through hole 74 contacts the top surface of the bushing portion 70. In addition, the head of the screw 54 contacts the peripheral portion of the opening on one axial side of the through hole 74, and the front end of the screw 54 contacts the inner circumferential surface of the threaded hole 72.

[0045] Additionally, a plurality of signal lines 76 are connected to the circuit board 20. These signal lines 76 are connected via connector terminals 58 of the connector member 24 (see reference 20). Figure 1 It is connected to the conductive pattern 68 of the circuit board 20.

[0046] The first silicone gel 64 and the second silicone gel 66 are each formed of silicone gel. The first silicone gel 64 is sandwiched between the circuit substrate 20 and the plate-shaped portion 42 in a state of contact with the circuit substrate 20 and the plate-shaped portion 42. Similarly, the second silicone gel 66 is sandwiched between the circuit substrate 20 and the plate-shaped portion 42 in a state of contact with the circuit substrate 20 and the plate-shaped portion 42.

[0047] As described below, a first silicone gel 64 is disposed at a position corresponding to each of the plurality of switching elements 50, and a second silicone gel 66 is disposed at a position corresponding to each of the plurality of electrolytic capacitors 52.

[0048] Figure 3 From Figure 1 Observe from the side of arrow A2 Figure 1 The circuit board 20 shown is viewed from the following direction. Figure 3 As shown, 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.

[0049] From now on, when distinguishing the multiple switching elements 50, the multiple switching elements 50 will be referred to as switching elements 50-1 to 50-6 respectively. The multiple electrolytic capacitors 52 each have an anode terminal 52A and a cathode terminal 52B.

[0050] Figure 4 From Figure 1 Observe from the side of arrow A2 Figure 1 A view of the plate-shaped portion 42 of the center member 18 shown. Figure 4 The diagram shows a state in which a first silicone gel 64 and a second silicone gel 66 are coated on one side of the circuit board 20 of the plate-shaped portion 42.

[0051] In addition, Figure 4 In the diagram, the circuit board 20, multiple switching elements 50, and multiple electrolytic capacitors 52 are represented by imaginary lines (double-dotted lines) when the circuit board 20 is assembled on the plate-shaped portion 42.

[0052] With a first silicone gel 64 and a second silicone gel 66 coated on the surface of the circuit board 20 side of the plate-shaped portion 42, the circuit board 20 is assembled onto the plate-shaped portion 42, thereby the first silicone gel 64 and the second silicone gel 66 are sandwiched between the circuit board 20 and the plate-shaped portion 42 while in contact with the circuit board 20 and the plate-shaped portion 42.

[0053] As an example, the noise reduction structure 60 has first silicone gels 64 disposed at three locations corresponding to the distribution of the plurality of switching elements 50. Hereinafter, when distinguishing the first silicone gels 64 disposed at these three locations, the first silicone gels 64 disposed at the three locations will be referred to as first silicone gels 64-1 to 64-3, respectively.

[0054] First silicone gel 64-1 and first silicone gel 64-2 are integrally formed with second silicone gel 66. As an example, one end of first silicone gel 64-1 and second silicone gel 66 are continuously formed, and the other end of first silicone gel 64-2 and second silicone gel 66 are continuously formed.

[0055] The first silica gel 64-1, 64-2 and the second silica gel 66 are all formed in a linear shape. The first silica gel 64-3 is independent of the first silica gel 64-1, 64-2 and the second silica gel 66, and is also formed in a linear shape.

[0056] The first silicone gel 64-1 is disposed at a location where it electrostatically bonds with each of the plurality of switching elements 50-1, 50-2. Specifically, a portion of the first silicone gel 64-1 is disposed at a location overlapping each of the plurality of switching elements 50-1, 50-2 when viewed from above the circuit substrate 20. Viewing the circuit substrate 20 from above corresponds to... Figure 1 Observe the circuit board 20 from the side indicated by arrow A2.

[0057] The first silicone gel 64-2 is disposed at a location where it is electrostatically bonded to each of the plurality of switching elements 50-3 to 50-5. Specifically, a portion of the first silicone gel 64-2 is disposed at a location where it overlaps with each of the plurality of switching elements 50-3 to 50-5 when viewed from above on the circuit board 20.

[0058] The first silicone gel 64-3 is disposed at a location where it is electrostatically bonded to the plurality of switching elements 50-6. Specifically, a portion of the first silicone gel 64-3 is disposed at a location where it overlaps with the plurality of switching elements 50-6 when viewed from above on the circuit board 20.

[0059] As an example, the first silicone gels 64-1 to 64-3 are respectively disposed at positions that partially overlap with each of the plurality of switching elements 50-1 to 50-6, but the first silicone gels 64-1 to 64-3 may also be disposed at positions that completely overlap with each of the plurality of switching elements 50-1 to 50-6.

[0060] The second silicone gel 66 is disposed at a position where it is electrostatically bonded to each of the plurality of electrolytic capacitors 52. Specifically, a portion of the second silicone gel 66 overlaps with each of the cathode terminals 52B of the plurality of electrolytic capacitors 52 when viewed from above the circuit substrate 20, while the entire portion is disposed at a position where it does not overlap with the anode terminals 52A of the plurality of electrolytic capacitors 52 when viewed from above the circuit substrate 20.

[0061] As an example, multiple electrolytic capacitors 52 are arranged in a row, with each other facing the same direction. The cathode terminals 52B of the multiple electrolytic capacitors 52 are located on the opposite side from the anode terminals 52A of the multiple electrolytic capacitors 52.

[0062] That is, when the imaginary line L1 passing through the anode terminals 52A of the multiple electrolytic capacitors 52 is set when the circuit board 20 is viewed from above, the cathode terminals 52B of the multiple electrolytic capacitors 52 are located on one side B1 of the imaginary line L1, and the multiple switching elements 50 are located on the other side B2 of the imaginary line L1.

[0063] As an example, the circuit board 20 is fixed to the plate-shaped portion 42 by a plurality of screws 54. Hereinafter, when distinguishing the plurality of screws 54, the plurality of screws 54 will be referred to as screws 54-1 to 54-3 respectively.

[0064] Screws 54-1 and 54-2, among screws 54-1 to 54-3, form the aforementioned conductive connection portion 62. These screws 54-1 and 54-2 are connected via a conductive pattern (not shown) (equivalent to...). Figure 2 The conductive pattern 68 shown is connected to the cathode terminals 52B of a plurality of electrolytic capacitors 52. Hereafter, 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.

[0065] The second silicone gel 66 is disposed between the first silicone gels 64-1 to 64-3 and the conductive connections 62-1 and 62-2. That is, when the circuit board 20 is viewed from above, the conductive connections 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.

[0066] like Figure 2 As shown, according to the above structure, the noise reduction structure 60 includes a first noise propagation path 78 and a second noise propagation path 80.

[0067] In the first noise propagation path 78, electromagnetic noise from the multiple switching elements 50 propagates from the multiple switching elements 50 through the first silicone gel 64, the plate-shaped portion 42, the conductive connection portion 62 and the conductive pattern 68 to the cathode terminals 52B of the multiple electrolytic capacitors 52.

[0068] In the second noise propagation path 80, electromagnetic noise from the multiple switching elements 50 propagates from the multiple switching elements 50 via the first silicone gel 64, the plate-shaped portion 42 and the second silicone gel 66 to the cathode terminals 52B of the multiple electrolytic capacitors 52.

[0069] Figure 5 yes Figure 1The equivalent circuit diagram of the brushless motor 10 is shown. The inverter circuit 82 consists of multiple switching elements 50 (see reference). Figure 3 , Figure 4 )form.

[0070] In the noise reduction structure 60 described above, at least a portion of the second silicone gel 66 overlaps with the cathode terminals 52B of the plurality of electrolytic capacitors 52 when viewed from above the circuit substrate 20, while the entire second silicone gel 66 does not overlap with the anode terminals 52A of the plurality of electrolytic capacitors 52 when viewed from above the circuit substrate 20. Thus, the second silicone gel 66 and the plurality of electrolytic capacitors 52 are electrostatically bonded. That is, the second silicone gel 66, serving as a dielectric, is connected between the conductive pattern 68 on the cathode side where the cathode terminals 52B of the plurality of electrolytic capacitors 52 are connected and the plate-shaped portion 42.

[0071] Furthermore, when at least a portion of the second silicone gel 66 overlaps with the anode terminals 52A of the plurality of electrolytic capacitors 52 in a top view of the circuit substrate 20, and when the entire second silicone gel 66 does not overlap with the cathode terminals 52B of the plurality of electrolytic capacitors 52 in a top view of the circuit substrate 20, such as Figure 5 As shown by the imaginary line (double-dotted line), the second silicone gel 66 does not electrostatically bond with the plurality of electrolytic capacitors 52. That is, in this case, the second silicone gel 66 is in a state where it is connected between the conductive pattern 84 on the anode side for connecting the anode terminals 52A of the plurality of electrolytic capacitors 52 and the plate-shaped portion 42.

[0072] Next, the function and effects of one embodiment of this disclosure will be explained.

[0073] As detailed above, one embodiment of the brushless motor 10 of this disclosure includes a noise reduction structure 60 for reducing electromagnetic noise. In this noise reduction structure 60, such as... Figure 2 As shown, a conductive pattern 68 formed on the circuit board 20 is connected to the cathode terminals 52B of a plurality of electrolytic capacitors 52. The conductive pattern 68 and the plate-shaped portion 42 are connected via a conductive connection portion 62. Furthermore, a first silicone gel 64 is sandwiched between the circuit board 20 and the plate-shaped portion 42, in contact with both. This first silicone gel 64 is positioned at locations where it electrostatically bonds with the plurality of switching elements 50.

[0074] Therefore, through the first silicone gel 64, a first noise propagation path 78 is formed, through which electromagnetic noise from the multiple switching elements 50 propagates from the multiple switching elements 50 via the first silicone gel 64, the plate-shaped portion 42, the conductive connection portion 62, and the conductive pattern 68 to the cathode terminals 52B of the multiple electrolytic capacitors 52. Thus, the electromagnetic noise from the multiple switching elements 50 can be absorbed by the multiple electrolytic capacitors 52, thereby suppressing the electromagnetic noise generated from the multiple switching elements 50 from flowing out to the outside of the brushless motor 10, for example, via the multiple signal lines 76.

[0075] Additionally, a second silicone gel 66 is sandwiched between the circuit board 20 and the plate-shaped portion 42 while in contact with both the circuit board 20 and the plate-shaped portion 42. This second silicone gel 66 is positioned at locations where it is electrostatically bonded to the plurality of electrolytic capacitors 52.

[0076] Therefore, through the second silicone gel 66 and the aforementioned first silicone gel 64, a second noise propagation path 80 is formed, through which electromagnetic noise from the multiple switching elements 50 propagates from the multiple switching elements 50 via the first silicone gel 64, the plate-shaped portion 42, and the second silicone gel 66 to the cathode terminals 52B of the multiple electrolytic capacitors 52. Thus, in addition to the first noise propagation path 78, electromagnetic noise can also propagate to the multiple electrolytic capacitors 52 via the second noise propagation path 80. Therefore, compared to a structure that propagates electromagnetic noise to the multiple electrolytic capacitors 52 only through the first noise propagation path 78, the absorption efficiency of electromagnetic noise in the multiple electrolytic capacitors 52 can be improved.

[0077] Furthermore, a portion of the first silicone gel 64 is disposed at a position overlapping with the plurality of switching elements 50 when the circuit board 20 is viewed from above. This allows the first silicone gel 64 to be appropriately electrostatically bonded to the plurality of switching elements 50.

[0078] Furthermore, a portion of the second silicone gel 66 overlaps with the cathode terminals 52B of the plurality of electrolytic capacitors 52 when viewed from above the circuit board 20, while the entire portion is positioned where it does not overlap with the anode terminals 52A of the plurality of electrolytic capacitors 52 when viewed from above the circuit board 20. This allows for proper electrostatic bonding between the second silicone gel 66 and the plurality of electrolytic capacitors 52.

[0079] Furthermore, 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 the path length of the first noise propagation path 78, the absorption efficiency of electromagnetic noise in the plurality of electrolytic capacitors 52 can be improved compared to, for example, the path length of the second noise propagation path 80 being greater than or equal to the path length of the first noise propagation path 78.

[0080] In addition, such as Figure 4As shown, the first silicone gel 64-1 is formed in a linear shape and overlaps with multiple switching elements 50-1 and 50-2 when the circuit substrate 20 is viewed from above. The first silicone gel 64-2 is also formed in a linear shape and overlaps with multiple switching elements 50-3 to 50-5 when the circuit substrate 20 is viewed from above. Therefore, compared to, for example, arranging the first silicone gel 64 for each of the multiple switching elements 50, the coating process of the first silicone gel 64 can be simplified.

[0081] Furthermore, the second silicone gel 66 is formed in a linear shape and overlaps with the cathode terminals 52B of the plurality of electrolytic capacitors 52 when the circuit board 20 is viewed from above. Therefore, the coating process of the second silicone gel 66 can be simplified compared to, for example, arranging the second silicone gel 66 for each of the plurality of electrolytic capacitors 52.

[0082] Furthermore, the noise reduction structure 60 utilizes the plate-shaped portion 42 of the central member 18 as a conductive member for propagating electromagnetic noise. Therefore, for example, the structure of the noise reduction structure 60 can be simplified compared to the case of using a dedicated conductive member for propagating electromagnetic noise.

[0083] Next, a variation of one embodiment of the present disclosure will be described.

[0084] Figure 6 It means Figure 2 The diagram shows a modified example of the noise reduction structure 60. Figure 7 From Figure 1 Observe from the side of arrow A2 Figure 6 A view of the plate-like portion 42 of the center member 18 in the modified example shown. In the above embodiment, as a preferred example, a first silicone gel 64 and a second silicone gel 66 are used. However, for example, if the first silicone gel 64 is sufficient, such as Figure 6 , Figure 7 As shown, the second silicone gel 66 can also be omitted (see...). Figure 2 , Figure 4 ).

[0085] In addition, 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 relative to the anode terminals 52A of the plurality of electrolytic capacitors 52. However, the cathode terminals 52B of the plurality of electrolytic capacitors 52 may also be located on the side of the plurality of switching elements 50 relative to the anode terminals 52A of the plurality of electrolytic capacitors 52.

[0086] If configured in this way, for example, the cathode terminals 52B of the plurality of electrolytic capacitors 52 are located on the opposite side of the plurality of switching elements 50 relative to the anode terminals 52A of the plurality of electrolytic capacitors 52 (see reference). Figure 4Compared to the previous method, the distance between the cathode terminals 52B of the multiple electrolytic capacitors 52 and the multiple switching elements 50 is shortened. Therefore, Figure 2 The length of the second noise propagation path 80 shown is shortened, so electromagnetic noise can be effectively propagated to multiple electrolytic capacitors 52 through the second noise propagation path 80.

[0087] Furthermore, in the above embodiment, the noise reduction structure 60 is a structure that includes a plate-shaped portion 42 of the central member 18, but it may also be a structure that includes a substrate housing 22 instead of the plate-shaped portion 42. In this case, the substrate housing 22 is equivalent to an example of a "conductive member".

[0088] Furthermore, in the above embodiment, as an example of "first dielectric" and "second dielectric", a first silicone gel 64 and a second silicone gel 66, which are silicone gels, were used. However, first dielectrics and second dielectrics other than silicone gels may also be used. Additionally, as an example of "first dielectric" and "second dielectric", first dielectrics and second dielectrics that are dielectric greases may also be used.

[0089] Furthermore, the arrangement of the plurality of switching elements 50 and the plurality of electrolytic capacitors 52 in the above embodiment is one example, but other arrangements are also possible. Additionally, the arrangement and shape of the first silicone gel 64 and the second silicone gel 66 are one example, but other arrangements are also possible.

[0090] In addition, in the above embodiment, a portion of the first silicone gel 64 is disposed at a position that overlaps with each of the plurality of switching elements 50 when viewed from above the circuit substrate 20. However, for example, a plurality of first silicone gels 64 may also be used, each of which overlaps with each of the plurality of switching elements 50 when viewed from above the circuit substrate 20.

[0091] In addition, in the above embodiment, a portion of the second silicone gel 66 is disposed at a position that overlaps with each of the plurality of electrolytic capacitors 52 when viewed from above the circuit substrate 20. However, for example, a plurality of second silicone gels 66 may also be used, each of which overlaps with each of the plurality of electrolytic capacitors 52 when viewed from above the circuit substrate 20.

[0092] In addition, in the above embodiment, as a preferred example, the first silicone gel 64 is provided corresponding to all the switching elements 50 mounted on the circuit board 20, but it is also possible to provide the first silicone gel 64 only corresponding to a portion of all the switching elements 50 mounted on the circuit board 20.

[0093] In addition, in the above embodiment, as a preferred example, the second silicone gel 66 is provided corresponding to all the electrolytic capacitors 52 mounted on the circuit board 20, but it is also possible to provide the second silicone gel 66 only corresponding to a portion of all the electrolytic capacitors 52 mounted on the circuit board 20.

[0094] In addition, in the above embodiment, screw 54 and through hole 74 are used as an example of "conductive connection part", but structures other than screw 54 and through hole 74 can also be used.

[0095] The above describes one embodiment of the present disclosure. However, the present disclosure is not limited to the above. In addition to the above, various modifications and implementations can be made without departing from the spirit of the present disclosure.

[0096] Furthermore, the entire contents of Japanese Patent Application 2020-186784 are incorporated herein by reference.

[0097] Furthermore, all documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent that each document, patent application, and technical standard is specifically and separately described.

[0098] Regarding one embodiment of the present disclosure described above, the following notes are further disclosed.

[0099] (Postscript 1)

[0100] A brushless motor, the brushless motor including a noise reduction structure for reducing electromagnetic noise, wherein,

[0101] The above noise reduction structure has the following characteristics:

[0102] A circuit board, wherein a switching element and an electrolytic capacitor are mounted on the first side of the circuit board;

[0103] A conductive component, wherein the conductive component is opposite to a second surface of the circuit board on the side opposite to the first surface;

[0104] The conductive connection portion connects the conductive pattern formed on the circuit board and the conductive pattern connected to the cathode terminal of the electrolytic capacitor to the conductive member; and

[0105] The dielectric is sandwiched between the circuit board and the conductive member in a state of contact with the circuit board and the conductive member, and is disposed at a position where it is electrostatically connected to the switching element.

[0106] (Postscript 2)

[0107] As described in Appendix 1, in the brushless motor, at least a portion of the dielectric is disposed at a position that overlaps with the switching element when the circuit board is viewed from above.

[0108] (Note 3)

[0109] As described in Appendix 1 or Appendix 2, the brushless motor,

[0110] The above noise reduction structure has the following characteristics:

[0111] As the first dielectric of the aforementioned dielectric; and

[0112] The second dielectric is sandwiched between the circuit board and the conductive member in a state of contact with the circuit board and the conductive member, and is disposed at a position where it is electrostatically connected to the electrolytic capacitor.

[0113] (Postscript 4)

[0114] As described in Appendix 3, in the brushless motor, at least a portion of the second dielectric overlaps with the cathode terminal of the electrolytic capacitor when the circuit board is viewed from above, while all of it is positioned in a position that does not overlap with the anode terminal of the electrolytic capacitor when the circuit board is viewed from above.

[0115] (Note 5)

[0116] As described in Appendix 3 or Appendix 4, in a brushless motor, the second dielectric is disposed between the first dielectric and the conductive connection portion.

[0117] (Note 6)

[0118] The brushless motor described in any of Appendix 3 to Appendix 5, wherein,

[0119] Multiple switching elements are mounted on the first surface of the aforementioned circuit board.

[0120] The first dielectric is formed in the shape of a line and overlaps with the plurality of the switching elements when viewed from above on the circuit board.

[0121] (Note 7)

[0122] The brushless motor described in any of Appendix 3 to Appendix 6, wherein,

[0123] Multiple electrolytic capacitors are mounted on the first surface of the aforementioned circuit board.

[0124] The second dielectric is formed in the shape of a line and overlaps with the cathode terminals of the plurality of electrolytic capacitors when viewed from above on the circuit board.

[0125] (Postscript 8)

[0126] The brushless motor described in any of Notes 3 to 7, wherein the first dielectric and the second dielectric are integrally formed.

[0127] (Note 9)

[0128] The brushless motor described in any of Notes 3 to 8, wherein the first dielectric and the second dielectric are silicone gel.

[0129] (Postscript 10)

[0130] The brushless motor described in any of Appendix 1 to Appendix 9, wherein the cathode terminal of the electrolytic capacitor is located on the opposite side to the anode terminal of the electrolytic capacitor.

[0131] (Postscript 11)

[0132] The brushless motor described in any of Appendix 1 to Appendix 10, wherein the cathode terminal of the electrolytic capacitor is located on the side of the switching element relative to the anode terminal of the electrolytic capacitor.

[0133] (Postscript 12)

[0134] The brushless motor described in any of Appendix 1 to Appendix 11, wherein,

[0135] The above-mentioned brushless motors include:

[0136] The rotor has a top-cylindrical rotor housing;

[0137] The stator, which is housed inside the rotor housing; and

[0138] The center component has a plate-like portion opposite to the opening of the rotor housing and holds the stator.

[0139] The circuit board is disposed opposite to the plate-shaped portion on the side opposite to the rotor.

[0140] The aforementioned conductive component is the aforementioned plate-shaped portion.

[0141] (Postscript 13)

[0142] The brushless motor described in any of Appendix 1 to Appendix 11, wherein,

[0143] The above-mentioned brushless motors include:

[0144] The rotor has a top-cylindrical rotor housing;

[0145] The stator, which is housed inside the rotor housing; and

[0146] The center component has a plate-like portion opposite to the opening of the rotor housing and holds the stator.

[0147] The circuit board is disposed opposite to the plate-shaped portion on the side opposite to the rotor.

[0148] The aforementioned conductive component is a substrate housing that houses the aforementioned circuit board.

Claims

1. A brushless electric motor, the brushless electric motor including a noise reduction structure for reducing electromagnetic noise, The noise reduction structure has: A circuit board, wherein a switching element and an electrolytic capacitor are mounted on a first side; A conductive component, wherein the conductive component is opposite to a second surface of the circuit board on the side opposite to the first surface; A conductive connection portion, wherein the conductive connection portion connects the conductive pattern formed on the circuit board and the conductive pattern connected to the cathode terminal of the electrolytic capacitor to the conductive member; as well as A dielectric material is sandwiched between the circuit board and the conductive member in contact with the circuit board and the conductive member, and is disposed at a position where it is electrostatically coupled to the switching element.

2. The brushless motor as described in claim 1, characterized in that, At least a portion of the dielectric is disposed at a position that overlaps with the switching element when the circuit board is viewed from above.

3. The brushless motor as described in claim 1 or 2, characterized in that, The noise reduction structure has: As the first dielectric of the dielectric; as well as The second dielectric is sandwiched between the circuit board and the conductive member in a state of contact with the circuit board and the conductive member, and is disposed at a position that is electrostatically connected to the electrolytic capacitor.

4. The brushless motor as described in claim 3, characterized in that, At least a portion of the second dielectric overlaps with the cathode terminal of the electrolytic capacitor when the circuit board is viewed from above, while the entire second dielectric is disposed in a position that does not overlap with the anode terminal of the electrolytic capacitor when the circuit board is viewed from above.

5. The brushless motor as described in claim 3 or 4, characterized in that, The second dielectric is disposed between the first dielectric and the conductive connection portion.

6. The brushless motor as described in any one of claims 3 to 5, characterized in that, A plurality of the switching elements are mounted on the first surface of the circuit board. The first dielectric is formed in a linear shape and overlaps with the plurality of switching elements when viewed from above on the circuit board.

7. The brushless motor as described in any one of claims 3 to 6, characterized in that, 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 when viewed from above on the circuit board.

8. The brushless motor as described in any one of claims 1 to 7, characterized in that, The brushless motor includes: A rotor having a top-cylindrical rotor housing; Stator, the stator being housed inside the rotor housing; and A central component, having a plate-like portion opposite to an opening in the rotor housing, and holding the stator. The circuit board is disposed opposite to the plate-shaped portion on the side opposite to the rotor. The conductive component is the plate-shaped portion.

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