JP2017229124A - Dc brushless motor and ventilation blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC brushless motor securing necessary radiation performance even when being used with high output.SOLUTION: A DC brushless motor comprises: a tubular frame 1 constituted of a thermal conductivity material; a stator 2 being mounted inside a body portion of the tubular frame 1 and having a coil 2a; an output pin 5 being erected on the stator 2 and connected to an end portion of the coil 2a; a rotor 6 arranged in a rotatable manner with a shaft 6c being a rotating shaft as a center; a circuit board 8 being mounted with an electronic component constituting a driving circuit and connected to the output pin 5; a heat sink 9 thermally brought into contact with the electronic component; and a motor cover 12 being made of metal and closing an opening 1o of the tubular frame 1 while being thermally brought into contact with the heat sink 9. The heat sink 9 includes a substrate connection terminal 9a thermally connected to the circuit board 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a DC brushless motor and a ventilation fan for a ventilation fan provided with a built-in substrate.

  In the structure of a direct current (DC) brushless motor that is an electric motor, a rotor is arranged in a case cover in which a stator around which a coil is wound is fitted. Then, the control circuit board provided with the shaft through hole is fixed to the stator, and the case is attached. The DC brushless motor is equipped with a drive circuit that generates a current for rotating the rotor and a microcomputer that controls the drive circuit.

  DC brushless motors incorporating a drive circuit and a control circuit board are expanding the application scale and application range in various product fields, mainly due to the increasing demand for energy saving and product miniaturization. In this trend, the demand for DC brushless motors with built-in drive circuits and control circuit boards is growing even in consumer systems such as ventilation fans, where the application scale and application range have not been so large.

  When considering the application of DC brushless motors to consumer systems, in many cases, the obstacle is that DC merit including energy saving and miniaturization is not worth the cost increase from AC motors. It is a point judged. In order to remove the obstacles, various technologies have been disclosed which aim at reducing material costs and manufacturing costs and improving added value.

  For example, Patent Document 1 discloses the following DC brushless motor technology. A cylindrical resin bracket is attached to a cylindrical metal stator frame. The resin bracket has a through hole through which an output pin connected to the winding of the stator is inserted. This through hole is closed by a moisture-proof seal. A bearing holding portion is provided on the load side of the resin bracket to hold the rotor. On the other hand, a circuit board on which electronic components are mounted is housed on the non-load side, and the electronic components are conductively connected to the inserted pins. Further, the inside of the upper surface of the metal motor cover radiates heat by coming into contact with the electronic component and closes the opening of the stator frame. With the above configuration, productivity is improved and cost reduction is achieved while ensuring heat dissipation and moisture resistance.

Japanese Patent No. 5268845

  According to the technique disclosed in Patent Document 1, heat is radiated with a simple structure in which an electronic component and a motor cover are brought into contact with each other, and a seal material is simply applied to a through hole of an output pin electrically connected to a winding. Since moisture resistance can be secured, cost reduction and productivity improvement are realized. However, since the heat radiating means relies only on heat conduction from the electronic component to the motor cover, there is a possibility that the heat radiating performance is insufficient in a high-power DC brushless motor. In addition, if there is a large gap between the inner surface of the motor cover and the heat generating component to be dissipated and there are high-profile components other than the heat generating component, an additional drawing process is required to connect the motor cover to the heat generating component. Deteriorating. In addition, since the cover shape cannot be shared with the cover for the AC motor, there is a concern about the burden of creating a new mold.

  As described above, for the heat dissipation of the DC brushless motor, without using a heat dissipation means that requires manufacturing costs, such as application of potting material, integral molding of the substrate case and the heat sink and addition of a metal cover for heat dissipation, In addition, there is a demand for a configuration that pursues cost reduction by eliminating functions other than the minimum necessary functions.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a DC brushless motor that ensures necessary heat dissipation performance even when used at high output.

  In order to solve the above-described problems and achieve the object, the present invention provides a cylindrical frame made of a thermally conductive material, a stator mounted in a barrel portion of the cylindrical frame, and provided with a coil, and a rotating shaft. , A circuit board on which electronic components constituting the drive circuit are mounted and connected to a stator coil, a heat sink in thermal contact with the electronic components, and a heat sink And a motor cover made of a thermally conductive material that contacts and closes the opening of the cylindrical frame. The heat sink includes a board connection terminal that is thermally connected to the circuit board.

  According to the present invention, there is an effect that it is possible to obtain a DC brushless motor that ensures necessary heat dissipation performance even when used at high output.

Partial sectional view of DC brushless motor of Embodiment 1 Part A enlarged view of FIG. The top view of the circuit board in the state where the heat sink in the DC brushless motor of Embodiment 1 was connected The principal part enlarged view of the modification of the DC brushless motor of Embodiment 1 Partial sectional view of DC brushless motor according to Embodiment 2 The top view of the circuit board in the state where the heat sink in the DC brushless motor of Embodiment 2 was connected Partial sectional view of DC brushless motor of Embodiment 3 FIG. 7 is a top view of the intermediate layer of the multilayer substrate in FIG. FIG. 7 is a top view of the intermediate layer of the multilayer substrate in FIG. Partial sectional view of DC brushless motor of Embodiment 4 Part B enlarged view of FIG. Top view of the circuit board to which the heat sink of Embodiment 4 is connected Sectional drawing of the ventilation fan carrying the DC brushless motor of Embodiment 5 of this invention

  Hereinafter, embodiments of a DC brushless motor and a ventilation fan according to the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to this embodiment, and can be appropriately changed without departing from the gist of the present invention. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings. Further, even a cross-sectional view may not be hatched for easy viewing of the drawing.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional view of DC brushless motor 201 according to Embodiment 1 of the present invention. First, the overall configuration of the DC brushless motor 201 will be described with reference to FIG.

  The DC brushless motor 201 according to the first embodiment includes a metal cylindrical frame 1 that is a heat conductive material, a stator 2 that is mounted in a body portion of the cylindrical frame 1, and includes a coil 2 a, and stands on the stator 2. A circuit in which an output pin 5 provided and connected to the end of the coil 2a, a rotor 6 disposed so as to be rotatable around a rotation axis, and an electronic component 101 constituting a drive circuit are mounted and connected to the output pin 5. A substrate 8, a heat sink 9 that is in thermal contact with the electronic component, and a metal motor cover 12 that is a thermally conductive material that is in thermal contact with the heat sink 9 and closes the opening 1 o of the cylindrical frame 1. With. The heat sink 9 includes a board connection terminal 9 a that is thermally connected to the circuit board 8.

  Furthermore, it has an insulator 4 on the opposite side as well as an insulator 3 on the load side for insulating and protecting the coil 2a. Further, the heat sink 9 has a board connection terminal 9a and forms an arch shape surrounding the shaft 6c, and the board side contacts the electronic component 101 on the circuit board 8 through a heat radiating sheet 10 that is compressed and deformed. ing. In addition, a motor cover 12 that closes the opening 1 o of the cylindrical frame 1 is provided. The motor cover 12 has a bearing holding portion 12 a and contacts the heat sink 9 via the high thermal conductor 11. A hole for taking out the lead terminal is formed in the central portion of the motor cover 12, but since it is closed by a terminal block (not shown), the seal structure can be maintained. The high heat conductor is a material having high heat conductivity, and a heat conductive material such as a metal or a heat conductive resin can be used.

  The rotor 6 is rotatably disposed inside the stator 2 around the shaft 6c. At this time, the load-side bearing 6 a is held by the cylindrical frame 1. On the other hand, the bearing 6 b on the opposite load side is held by a bearing holding portion 12 a formed on the motor cover 12. The bearing holding portion 12a is formed on the motor cover 12 to ensure strength. The higher the output motor, the larger the size and weight of the rotor, so that a strong holding mechanism is likely to be required.

  The substrate case 7 is inserted into the cylindrical frame 1 after the stator 2. At this time, the output pin 5 inserted through the through hole 7a protrudes to the mounting surface side of the circuit board 8 in the board case 7 and is electrically connected to the circuit board 8 by soldering. The DC brushless motor 201 is a three-phase drive motor often used for consumer use. In this case, three output pins 5 are provided for the U phase, the V phase, and the W phase. The diameter of the opening 7b of the substrate case 7 and the opening 8a of the circuit board is larger than the diameter of the bearing 6b on the anti-load side so that the rotor 6 can be inserted. The substrate case 7 is positioned in the axial direction by being brought into contact with the insulator 4 on the anti-load side.

  A frame flange 1 a and a cover flange 12 b are formed on the outer periphery of the opening end of the cylindrical frame 1 and the motor cover 12. The motor cover 12 is externally fitted to the cylindrical frame 1, and the cover flange 12b is brought into contact with the frame flange 1a and screwed to close the opening 1o of the cylindrical frame 1. The motor cover 12 and the heat sink 9 are in thermal contact via the high thermal conductor 11. For the high thermal conductor 11 through which the motor cover 12 and the heat sink 9 are in thermal contact, an adhesive such as silicon or epoxy resin may be considered. In the first embodiment, the high thermal conductor 11 is interposed between the motor cover 12 and the heat sink 9, but the motor cover 12 and the heat sink 9 are joined by using a joining means for direct contact such as screw tightening. Also good.

  FIG. 2 is an enlarged view of part A in FIG. FIG. 3 is a top view of the circuit board in a state where the heat sink in FIG. 1 is connected. Hereinafter, the details of the heat dissipation structure in the first embodiment will be described with reference to FIGS. 2 and 3.

  Various electronic components 101 mounted on the circuit board 8 constitute each function including a drive unit 101a, a control unit 101b, and a power supply unit 101c. The drive unit 101a is a combination of six discrete elements including a one-chip inverter IC (Integrated Circuit) or IGBT (Insulated Gate Bipolar Transistor) and a motor driver IC. A configuration using a three-phase bridge driver is conceivable. The control unit 101b may be configured using a control element such as a microcomputer or a programmable logic controller (PLC). The power supply unit 101c is equipped with a power supply terminal connected to an external power supply. Furthermore, when an EMC (Electro Magnetic Compatibility) filter and an external power source are AC power sources, a configuration using an AC-DC converter is conceivable.

  When the external power supply is supplied to the power supply unit 101c, the drive unit 101a energizes and drives the coil 2a according to a control command from the control unit 101b, thereby generating a drive torque for rotating the rotor 6 connected to the shaft 6c. generate. At this time, main heat generating components in the circuit board 8 are components constituting the drive unit 101a and the power supply unit 101c. Hereinafter, in Embodiment 1, the heat generating component 101d in the drive unit 101a will be described as a heat dissipation target.

  As shown in FIG. 2, the heat generating component 101 d is mounted on the circuit board 8, and the upper surface is connected to the heat sink 9 via the heat radiating sheet 10, and the heat sink 9 contacts the motor cover 12 via the high thermal conductor 11. ing. For this reason, heat dissipation of the heat generating component 101d is performed by heat transfer using the motor cover 12 that is in contact with the heat dissipation sheet 10, the heat sink 9, and the high thermal conductor 11. In addition to improving the thermal conductivity between the heat-generating component 101d and the heat sink 9, the heat-dissipating sheet 10 relieves stress on the heat-generating component 101d and the entire circuit board 8 due to an assembly error in the axial direction due to a compressive deformation characteristic.

  In addition, as a member having the characteristic of compressive deformation with respect to the stress, as shown in an enlarged view of a main part of a modification of the DC brushless motor according to the first embodiment in FIG. It is also possible to provide it. The substrate support portion 7c having a spring property exhibits a reaction force of the spring according to the law of elasticity against the pressure applied to the heat generating component 101d and the entire circuit board 8 by attaching the heat sink 9. By designing the structure so that the stress and the reaction force of the spring antagonize, it is possible to eliminate the heat radiating sheet 10 or to have a configuration in which the high thermal conductor 11 is interposed instead of the heat radiating sheet 10. As described above, the cost can be reduced by interposing the high thermal conductor 11 in place of the heat radiating sheet 10.

  Next, the heat sink 9 increases the contact area with the motor cover 12 while avoiding interference with the components other than the drawing portion 12c and the heat generating component 101d formed when the bearing holding portion 12a is provided and the output pin 5. For this reason, as shown in FIG. 3, an arch shape surrounding the shaft 6c is formed as viewed from the axial direction. In the first embodiment, components other than the heat generating component 101d are components of the power supply unit 101c. Although FIG. 3 shows a shape in which a part of the ring is missing, another shape such as a polygon may be used. The substrate connection terminal 9a is joined to the heat sink 9 by integral molding, caulking, or screw tightening.

  When the heat sink 9 is pressed against the heat radiating sheet 10, the board connection terminals 9 a are inserted into the through holes 8 b on the circuit board 8, and are connected and fixed by soldering. As a connection method, other conductive connection means or mechanical connection using an adhesive may be used as long as the connection method can obtain a connection portion having high thermal conductivity.

  In FIG. 3, the number of board connection terminals 9a is three, but two or less or four or more in consideration of the required heat dissipation performance, mounting stability, or the space for arranging the through holes 8b on the circuit board 8. It is also good. Naturally, the heat dissipation performance is higher as the number of substrate connection terminals 9a is larger. Furthermore, the closer the position of the board connection terminal 9a is to the heat generating component 101d, the higher the heat transfer effect.

  By adopting the configuration of the first embodiment, the circuit board 8 and the heat sink 9 are connected via the board connection terminal 9a, so that the heat generating component 101d → the heat sink 9 → the motor cover 12 is transmitted with a simple configuration and manufacturing method. In addition to the heat path, a heat transfer path of the heat generating component 101d → the circuit board 8 → the heat sink 9 → the motor cover 12 is obtained. Thereby, the heat dissipation performance required for the DC brushless motor 201 can be ensured while keeping materials and manufacturing costs low.

Embodiment 2. FIG.
In order to further improve the heat dissipation performance of the heat dissipation structure described above, the thermal resistance between the circuit board 8 and the heat sink 9 may be lowered. Hereinafter, in Embodiment 2, the structure which reduces the above-mentioned thermal resistance is shown using FIG. 5 and FIG. FIG. 5 is a partial cross-sectional view of the DC brushless motor according to the second embodiment, and FIG. 6 is a top view of the circuit board with the heat sink connected to the DC brushless motor according to the second embodiment. The circuit board 8 used in the DC brushless motor of the second embodiment is made of the same material as the circuit pattern so as to be in thermal contact with the substrate connection terminal 9a in order to increase the thermal conductivity with the heat sink 9 by the board connection terminal 9a. A solid pattern for heat dissipation that is patterned using the same process is formed.

  First, the configuration shown in FIGS. 5 and 6 will be described. FIG. 5 shows a configuration in which the heat sink 9 in FIG. 2 has a contact surface 9c of the circuit board 8 to improve thermal contact. The circuit board 8 is formed on the first solid pattern 8d including the contact surface 8c with the heat sink 9 and the second main surface 8B opposite to the first main surface 8A which is the first solid pattern forming surface. A solid pattern 8e is formed, and the heat dissipation sheet 10a is formed so as to include a heat generating component 101d that generates heat and a contact surface 8c. 6 is a top view of the circuit board 8 with the heat sink 9 in FIG. 5 connected thereto. The first solid pattern 8d is coupled to the through hole 8b.

  According to the configuration shown in FIGS. 5 and 6, since the heat sink 9 contacts the circuit board 8 via the contact surface 9c via the first solid pattern 8d having good thermal conductivity and the heat radiation sheet 10a, the heat sink 9 and the circuit The thermal resistance between the substrates 8 can be reduced. In FIG. 6, there are two first solid patterns 8 d including the contact surface 9 c of the heat sink 9 with the circuit board 8 and the contact surface 8 c on the circuit board 8. Considering the space for forming the solid pattern 8d, it may be one or three or more.

  Naturally, the heat dissipation performance is higher as the number and area of the contact surfaces 8c are larger. Furthermore, the closer the arrangement of the contact surface 8c is to the heat generating component 101d, the higher the heat transfer effect. Of course, the first solid pattern 8d should have a larger area from the viewpoint of exhibiting the effect of diffusing the heat generated by the heat generating component 101d on the circuit board 8. However, it is necessary to secure creepage distances for compliance with the Electrical Appliance and Material Safety Law or IEC (International Electrotechnical Commission: IEC), and to prevent failures and malfunctions caused by various causes including external noise and lightning surges. There is a restriction such as securing a distance between the negative potentials.

  Therefore, it is difficult to form a solid pattern for the electronic component 101, the output pin 5, or the entire space without pattern wiring. Moreover, the thermal resistance between the heat sink 9 and the circuit board 8 can be reduced by coupling the through hole 8b to which the board connection terminal 9a is soldered and the first solid pattern 8d. As shown in FIG. 5, when the solid pattern 8e formed on the surface opposite to the surface on which the first solid pattern 8d is formed is similarly coupled to the through hole 8b, the thermal resistance can be further reduced. The through hole and the solid pattern can be combined without increasing the cost by pattern design.

Embodiment 3 FIG.
Next, the configuration shown in FIGS. 7 to 9 will be described. FIG. 7 is a partial cross-sectional view of the DC brushless motor according to the third embodiment. FIG. 7 shows a configuration in which the circuit board 8 in FIG. 2 is formed of a multilayer substrate, and the second solid substrate 8f, the second solid pattern 8h of the third layer substrate 8g, and the third solid pattern 8i are combined with the through hole 8b. FIG. 8 and 9 are top views of the intermediate layer of the multilayer substrate in FIG.

  According to the configuration of the third embodiment shown in FIG. 7 to FIG. 9, the through hole 8b to which the board connection terminal 9a is soldered, the second solid pattern 8h, and the third solid pattern 8i are combined, so that the heat sink The thermal resistance between 9 and the circuit board 8 can be reduced. A solid pattern may be formed only on one of the second layer substrate 8f and the third layer substrate 8g. The second solid pattern 8h and the third solid pattern 8i should have a large area as in the case of the solid pattern in the configuration shown in FIGS. 5 and 6, but the above-described restrictions on the creepage distance or the distance between the ground potentials are limited. Therefore, it is difficult to make the entire space without the terminals, the output pins 5 and the pattern wiring of the electronic component 101 as a solid pattern. In the third embodiment, a four-layer substrate is taken as an example, but it goes without saying that the thermal resistance can be further reduced by increasing the number of substrate layers having a solid pattern coupled to the through-holes 8b. . However, since the substrate cost increases as the number of layers increases, it is necessary to consider the balance between heat dissipation performance and cost.

  As described above, according to the DC brushless motors of the second and third embodiments shown in FIGS. 5 to 9, the increase in material cost is suppressed, and the configuration and the manufacturing method are not complicated. Therefore, the heat radiation performance can be further improved at low cost.

  The through-hole 8b for heat dissipation described in the first to third embodiments has no problem even if the potential is floated, but if it is connected to a specific potential, the GND potential is desirable. The GND potential is a reference potential of various DC power sources for driving the driving unit 101a and the control unit 101b, and exhibits various noise countermeasure effects when connected to a solid pattern.

Embodiment 4 FIG.
A DC brushless motor according to the fourth embodiment will be described. 10 is a partial cross-sectional view of the DC brushless motor according to the fourth embodiment, FIG. 11 is an enlarged view of a portion B in FIG. 10, and FIG. 12 is a top view of the circuit board to which the heat sink of the fourth embodiment is connected. is there. First, the overall configuration of the DC brushless motor 301 will be described with reference to FIG. In addition, although description is abbreviate | omitted about the site | part of the same structure as Embodiment 1, the same code | symbol was attached | subjected to the same site | part.

  In the fourth embodiment, no opening is provided in the center of the substrate case 307 and the circuit board 308. The substrate case 307 is provided with a bearing holding portion 307b on the load side, and holds the bearing 6b on the opposite load side. Accordingly, a drawing portion 307 c is formed on the load side of the substrate case 307.

  In the fourth embodiment, since the bearing holding portion 307b is provided in the substrate case 307, the cover 312 does not have the bearing holding portion and the drawing portion. The cover flange 312a is the same as that in the first embodiment.

  In the fourth embodiment, by closing the through hole 307a with the moisture-proof sealing material 313, the installation space of the circuit board 308 is blocked from the outside air, so that the moisture resistance can be improved.

  FIG. 11 is an enlarged view of a portion B in FIG. FIG. 12 is a top view of the circuit board with the heat sink in FIG. 11 connected thereto. Hereinafter, details of the heat dissipation structure in the fourth embodiment will be described with reference to FIGS. 11 and 12. In addition, description is abbreviate | omitted about the site | part of the same structure as Embodiment 2. FIG. The same symbols are assigned to the same parts.

  Since the heat sink 309 has no drawing portion in the motor cover 312, it is possible to increase the contact area with the motor cover 312 while avoiding interference with components other than the heat generating component 101 d and the output pin 5. In the fourth embodiment, components other than the heat generating component 101d correspond to components of the power supply unit 101c. Although FIG. 12 shows a shape in which a part of the cylinder is missing, another shape such as a polygon may be used. The substrate connection terminal 309a is the same as that of the first embodiment, and is joined to the heat sink 309 by various joining methods such as integral molding, caulking, or screw tightening.

  With the above-described structure, the circuit board 308 and the heat sink 309 are connected to each other through the board connection terminal 309a in the DC brushless motor according to the second embodiment. In addition to the heat transfer path of 101d → heat sink 309 → motor cover 312, a heat transfer path of heat generating component 101d → circuit board 308 → heat sink 309 → motor cover 312 is obtained. As a result, the necessary heat dissipation performance can be secured even in the DC brushless motor 301 while keeping the material cost and the manufacturing cost low.

  Further, the thermal resistance reduction measures described in the second and third embodiments with reference to FIGS. 5 to 9 can be applied in the same manner as in the first embodiment. As a result, the increase in the cost of the DC brushless motor can be suppressed, and the thermal resistance between the circuit board 308 and the heat sink 309 can be reduced without complicating the configuration or the manufacturing method, thereby further improving the heat dissipation performance at a low cost. Can do.

Embodiment 5. FIG.
The DC brushless motor having the heat dissipation structure described in the first to fourth embodiments is suitable for a system including a ventilation fan that requires low cost and high productivity. In the fifth embodiment, an example of mounting the DC brushless motor described in the first to fourth embodiments on a ventilation fan will be described.

  FIG. 13 is a cross-sectional view of a ventilation fan equipped with the DC brushless motor according to the first to fourth embodiments. The DC brushless motor 201 or 301 of Embodiments 1 to 4 is mounted on the casing 402 of the ventilation fan 401, and the blower fan 403 is attached to the shaft 6c. After the housing 402 is embedded in the ceiling plate 404, a grill 405 is attached from below.

  When the DC brushless motor 201 or 301 is energized and driven, a driving torque is generated to rotate the blower fan 403. When the blower fan 403 rotates, an air flow indicated by an arrow in FIG. 13 is generated. The DC brushless motor 201 or 301 comes into contact with the housing 402 by the above-described screw tightening of the frame flange and the cover flange. As a result, heat generated by the energization drive is transferred to the housing 402, so that a heat dissipation effect is obtained.

  In the case of the DC brushless motor 301 according to the fourth embodiment, the circuit unit 406 and the motor unit 407 are partitioned by the substrate case 307 that has been subjected to moisture-proofing processing as described above. Thereby, since it has a structure in which moisture does not easily enter the circuit unit 406, the ventilation fan 401 can be used even in a high temperature and high humidity environment such as a bathroom.

  As described above, the ventilation fan equipped with the DC brushless motor in the fifth embodiment can obtain the heat dissipation effect described in the first to fourth embodiments. In addition, the installation of a DC brushless motor can realize energy saving and downsizing of the ventilation fan at low cost. Moreover, when the DC brushless motor of Embodiment 4 is mounted, moisture resistance can also be improved.

  In the above embodiment, the metal motor cover is used. However, the motor cover is not limited to metal, and may be made of a heat conductive material such as a heat conductive resin.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit and change the part.

  1 cylindrical frame, 1a frame flange, 1o opening, 2 stator, 2a coil, 3 load side insulator, 4 counter load side insulator, 5 output pin, 6 rotor, 6a load side bearing, 6b anti load Side bearing, 6c shaft, 7 substrate case, 7a through hole, 7b opening, 7c substrate support, 8 circuit board, 8a opening, 8b through hole, 8c contact surface, 8A first main surface, 8d first solid Pattern, 8B second main surface, 8e solid pattern formed on the opposite side of the first solid pattern forming surface, 8f second layer substrate, 8g third layer substrate, 8h second solid pattern, 8i third solid pattern, 9 Heat sink, 9a board connection terminal, 9c contact surface, 10 heat dissipation sheet, 10a heat dissipation sheet, 11 high thermal conductor, 12 motor cover, 12a shaft Holding part, 12b Cover flange, 12c Drawing part, 101 Electronic parts, 101a Drive part, 101b Control part, 101c Power supply part, 101d Heat generating part, 201 DC brushless motor, 301 DC brushless motor, 307 Substrate case, 307a Through hole, 307b Bearing holding part, 307c Drawing part, 308 Circuit board, 309 Heat sink, 309a Board connection terminal, 312 Motor cover, 312a Cover flange, 313 Moisture-proof sealant, 401 Ventilation fan, 402 Housing, 403 Fan, 404 Ceiling board, 405 Grill, 406 Circuit part, 407 Motor part.

Claims (13)

A cylindrical frame made of a thermally conductive material;
A stator mounted in the barrel of the cylindrical frame and provided with a coil;
A rotor arranged to be rotatable around a rotation axis;
A circuit board on which electronic components constituting a drive circuit are mounted and connected to the stator coil;
A heat sink in thermal contact with the electronic component;
A motor cover made of a thermally conductive material that is in thermal contact with the heat sink and closes the opening of the cylindrical frame;
The DC brushless motor, wherein the heat sink includes a board connection terminal that is thermally connected to the circuit board. The cylindrical frame and the motor cover are made of metal,
The stator is fitted in the body of the cylindrical frame;
The DC brushless motor according to claim 1, wherein a board case made of an insulating material is attached to the circuit board. The board case and the circuit board have an opening through which the rotor is inserted,
The motor cover has a bearing holding portion,
The DC brushless motor according to claim 2, wherein the bearing on the side opposite to the load of the rotor inserted through the opening is held by the bearing holding portion of the motor cover.   4. The DC brushless motor according to claim 1, wherein the electronic component is in thermal contact with the heat sink via a heat-dissipating sheet that compressively deforms. 5. The substrate case has a bearing holding portion that is shaped on the load side,
The DC brushless motor according to claim 2, wherein the bearing on the side opposite to the load of the rotor is held by the bearing holding portion of the substrate case. The stator coil and the circuit board are connected by output pins standing on the stator,
The substrate case has a through hole through which the output pin is inserted,
3. The DC brushless motor according to claim 2, wherein the through hole of the substrate case into which the output pin is inserted is closed with a moisture-proof sealing material.   The DC brushless motor according to claim 2, wherein the board case includes a board support portion that elastically holds the circuit board. The heat sink has a contact surface in thermal contact with the circuit board;
The DC brushless motor according to any one of claims 1 to 7, wherein the circuit board includes a solid pattern including a contact portion with the contact surface.   The DC brushless motor according to any one of claims 1 to 8, wherein the contact surface of the heat sink and the circuit board are in thermal contact with each other via a heat dissipation sheet. The circuit board has a through hole combined with the solid pattern,
10. The DC brushless motor according to claim 8, wherein a substrate connection terminal of the heat sink is inserted into and connected to the through hole. The circuit board is a multilayer wiring board having a solid pattern in an intermediate layer,
The DC brushless motor according to claim 10, wherein the substrate connection terminal of the heat sink is inserted into and connected to a through hole that is thermally connected to the solid pattern of the intermediate layer.   The DC brushless motor according to claim 10, wherein the through hole and the solid pattern are GND potentials in the circuit board.   A ventilation blower comprising the DC brushless motor according to any one of claims 1 to 12.

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