CN118017769A - Electronically commutated DC motor with encapsulated controller - Google Patents

Abstract

An EC motor with an encapsulated electronic controller. The electronic controller is encapsulated by creating a silicone mold to contain voids that are fine enough to allow some portions of the electronic controller adjacent to the voids to be encapsulated, while other portions of the electronic controller adjacent to places in the mold that do not have voids are not encapsulated.

Description

Electronically commutated DC motor with encapsulated controller

Cross Reference to Related Applications

This patent application is a continuation-in-part application of U.S. patent application Ser. No. 17/145,724, filed on even 11, 2021, which claims priority from U.S. provisional patent application Ser. No. 62/961,446, filed on even 15, 2020, which is incorporated herein by reference.

Technical Field

The present invention relates to electronically commutated Direct Current (DC) motors (EC motors), and more particularly to EC motor air cooling systems, optimized permanent magnet rotors, and integrally overmolded housings.

Background

In one embodiment, an inner rotor EC motor includes: a stator with a series of circumferentially spaced electromagnets, and a rotor located inside the stator and mounted on a shaft for rotation. The rotor has circumferentially spaced permanent magnets. The electronic controller controls the electrical energy delivered to the electromagnet coils of the stator. By controlling the electrical energy supplied to the stator coils, a rotating magnetic field is generated, which in turn attracts the permanent magnets of the rotor, causing the rotor to rotate on its shaft.

In another embodiment, an outer rotor EC motor includes a stator with circumferentially spaced electromagnets. Such EC motors have a rotor with permanent magnets positioned outside the stator. The operating principle of an EC motor, whether an inner rotor or an outer rotor, is substantially the same, i.e. a rotating magnetic field is generated by the stator, which attracts the permanent magnets of the rotor, causing the rotor to rotate.

During operation, both the electronic controller and the stator coils generate heat. As a result, EC motors require a system for dissipating heat from the control circuitry and stator coils.

The arrangement of the permanent magnets and steel laminations (STEEL LAMINATE) that make up the rotor can have an impact on the performance of the EC motor. This performance may be improved by constructing the rotor with a combination of permanent magnets sized and spaced around the rotor.

To ensure stability and durability of the electronics for the EC motor, the circuit board is typically encapsulated with epoxy to ensure that components mounted on the circuit board do not vibrate and become dislodged from the circuit board, or that the circuit board itself does not delaminate or otherwise fail.

During operation, switching of the current in the stator coils can lead to undesirable vibrations and noise. Furthermore, for some applications of EC motors, the cost and weight of the motor components (including the motor housing) are important to the purchaser.

Disclosure of Invention

To overcome the heat dissipation problem of the EC motor of the present invention, the EC motor includes an impeller fan attached to the rotating shaft of the rotor. The impeller fan draws ambient air into the housing of the EC motor. Ambient air is directed to the impeller fan through circumferentially spaced air inlets and then through radially oriented air passages adjacent the electronic controller. As ambient air passes through the radially oriented air passage, the ambient air absorbs heat from the electronic controller. Once ambient air has been drawn through the radially oriented air passages and into the impeller fan, the impeller fan will force the air to circulate along the axially oriented stator cooling passages between the stator coils. After heat is absorbed from the stator coils, air is expelled axially or radially through an air outlet in the housing. The impeller fan has planar fins oriented parallel to the rotor shaft so that cooling air flows in one direction regardless of the direction of rotation of the rotor and attached impeller fan.

For embodiments of the inner rotor, the stator includes a structural circular core back with inwardly extending teeth of laminated steel. An energizing coil is wound around and insulated from a single tooth. The teeth have concave ends defining a circular opening in which a circular inner rotor is positioned. The dimensions of the teeth and rotor provide an air gap between the concave ends of the teeth and the outer circumference of the rotor.

The inner rotor EC motor includes an overmolded housing including a cylindrical outer housing and inwardly extending stator coil sections. The stator coil sections encapsulate the coils and teeth (except for the concave ends). The housing is produced by over-molding the stator with plastic. The plastic is Rynite polyethylene terephthalate (available from DuPont) or any other plastic material having similar molding and heat transfer characteristics. Encapsulation of the stator coils and teeth reduces noise and vibration. Furthermore, the replacement of the metal cylindrical outer shell with a plastic shell contributes to weight saving and reduces material and manufacturing costs.

To optimize the performance of the inner rotor EC motor of the present invention, the rotor has permanent magnets and silicon steel laminations positioned around a central bushing. The silicon steel laminations are positioned around the outer circumference of the rotor and are circumferentially spaced around the rotor with gaps between adjacent silicon steel laminations. Rectangular shaped permanent magnets are inserted in the gaps between the silicon steel laminations. Wedge-shaped magnets are radially aligned with the silicon steel laminations and between the steel laminations and the central bushing of the rotor. By adjusting the size, shape and position of the silicon steel laminations, rectangular magnets and wedge magnets, the performance of the rotor is optimized.

For an outer rotor EC motor, the stator has a central bushing from which steel lamination teeth extend radially outward. The outer end of each tooth has an outer convex surface. The outer surfaces of the teeth form a circle. The rotor includes a cylindrical housing with a series of spaced apart permanent magnets attached to an inner surface of the cylindrical housing. The permanent magnets are sized to have inwardly facing concave surfaces that mate with the outer convex surfaces of the teeth. The cylindrical housing and the magnet are sized such that an air gap exists between the outer convex surface of the tooth and the inner concave surface of the permanent magnet. The rotor has a disk-shaped end cover with fan blades attached to an inner surface of the end cover. The cylindrical housing also has a series of circumferentially spaced openings that act as air outlets for air pressure generated by the fan blades.

The fan of the outer rotor EC motor draws air into the EC motor. Air enters the EC motor on one side of the stator, passes through a heat sink attached to the electronic circuit, passes axially through the stator air passage, and exits through an air outlet in the cylindrical housing of the rotor. Because the fan blades of the impeller fan are planar rather than curved, the cooling air is unidirectional regardless of the direction of rotation of the rotor and the fan.

To dampen vibrations, the stator is overmolded (encapsulated) with plastic. Likewise, the housing surrounding the stator and the electronic controller is also overmolded. In addition, the printed circuit board of the electronic controller is packaged so as to stabilize components mounted to the printed circuit board and to assist in dissipating heat from those components. The encapsulation of the printed circuit board utilizes a two-part silicone mold with a complex geometry to encapsulate portions of the circuit board with epoxy while leaving other portions unencapsulated. The silicone mold is supported by the exoskeleton during epoxy injection and epoxy curing.

Other objects, features, and advantages will become apparent after review of the following detailed description of the invention when taken in conjunction with the drawings and the appended claims.

Drawings

Fig. 1 is a perspective view of an inner rotor EC motor according to the present invention.

Fig. 2 is a side elevation view of an inner rotor EC motor in accordance with the present invention.

Fig. 3 is a left end elevational view of the inner rotor EC motor in accordance with the present invention.

Fig. 4 is a cross-sectional view of the inner rotor EC motor according to the present invention, as seen along line 4-4 of fig. 3.

Fig. 5 is a cross-sectional view of the inner rotor EC motor according to the present invention, as seen along line 5-5 of fig. 3.

Fig. 6 is a perspective view of an inner rotor EC motor according to the present invention with the electronic controller removed to show internal details.

Fig. 7 is a right end elevational view of the inner rotor EC motor according to the present invention with the electronic controller and impeller fan removed to show internal details.

Fig. 8 is a perspective view of the stator, rotor and impeller fan of the inner rotor EC motor according to the present invention.

Fig. 9 is a perspective view of the stator and rotor of the inner rotor EC motor according to the present invention.

Fig. 10 is a perspective view of a stator and a rotor of an inner rotor EC motor according to the present invention.

Fig. 11 is a right end elevation view of the stator and rotor of the inner rotor EC motor according to the present invention.

Fig. 12 is a perspective view of a first embodiment of a rotor (ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 13 is a front view of a first embodiment of a rotor (ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 14A and 14B are schematic views of a first embodiment of a rotor (ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 15A and 15B are schematic views of a first embodiment of a rotor (ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 16 is a front view of a second embodiment of a rotor (neo-ferrite) of an inner rotor EC motor according to the present invention.

Fig. 17A and 17B are schematic diagrams of a second embodiment of a rotor (neodymium-ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 18 is a schematic diagram of a second embodiment of a rotor (neodymium-ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 19A to 19D are schematic views of a second embodiment of a rotor (neodymium-ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 20 is a schematic diagram of a second embodiment of a rotor (neodymium-ferrite rotor) of an inner rotor EC motor according to the present invention.

Fig. 21 is a perspective view of an outer rotor EC motor according to the present invention.

Fig. 22 is a perspective view of an outer rotor EC motor according to the present invention.

Fig. 23 is a perspective view of an outer rotor EC motor with an outer rotor removed according to the present invention.

Fig. 24 is a perspective view of an outer rotor EC motor with an outer rotor removed according to the present invention.

Fig. 25 is a perspective view of an outer rotor EC motor with the outer rotor and stator cover (stator cowl) removed in accordance with the present invention.

FIG. 26 is a front elevation view of an outer rotor EC motor with the outer rotor, stator cover, and stator removed in accordance with the present invention.

FIG. 27 is a right side elevation view of an outer rotor EC motor with the outer rotor, stator cover and stator removed in accordance with the present invention.

Fig. 28 is a side elevation view of an outer rotor EC motor in accordance with the present invention.

Fig. 29 is a perspective view of a rotor of an outer rotor EC motor according to the present invention.

Fig. 30 is a perspective view of a stator of an outer rotor EC motor according to the present invention.

Fig. 31 is a cross-sectional view of an outer rotor EC motor in accordance with the present invention, as seen along line 31-31 of fig. 22.

Fig. 32 is a perspective view of a precision bottom master mold (master mold) according to the present invention.

Fig. 33 is a perspective view of a bottom silicone mold created from a precision bottom master mold in accordance with the present invention.

Fig. 34 is a perspective view of a precision top master mold according to the present invention.

Fig. 35 is a perspective view of a top silicone mold created from a precision top master mold in accordance with the present invention.

FIG. 36 is a cross-sectional view of a precision bottom female mold in accordance with the present invention.

Fig. 37A to 37C are schematic cross-sectional views of a process of packaging a circuit board of an electronic controller of an EC motor according to the present invention.

Detailed Description

Turning to fig. 1-6, an inner rotor, electronically commutated DC motor 10 (inner rotor EC motor) has an outer housing 20, the outer housing 20 comprising a cylindrical controller housing 14, a cylindrical stator housing 16, and a right end portion 12. The cylindrical controller housing 14 is attached to the cylindrical stator housing 16 by means of circumferentially spaced screws 21. The electronic controller 22 is mounted within the cylindrical controller housing 14, the electronic controller 22 including a printed circuit board 202 with a heat sink 206. The inner rotor EC motor 10 has a left end 24 and a right end 26.

The inner rotor EC motor 10 has an outer stator 30 and an inner ferrite rotor 62. Referring to fig. 8-11, stator 30 has a structural circular core back 32, core back 32 having inwardly extending steel lamination teeth 34 terminating in concave ends 35. The teeth 34 are circumferentially spaced about the circular core back 32 and define the opening 28 for receiving the rotor 62. The teeth 34 are wound with electromagnetic coils 38 insulated from the teeth 34.

The right end portion 12 of the housing 20, the cylindrical stator housing 16 and the stator coil section 18 are produced by plastic over-molding the stator 30. The plastic overmold encapsulates all of the stator circular core back 32, stator coils 38, and teeth 34 except for the concave ends 35 of the teeth 34. Due to the over-molding of the circular core back 32, teeth 34 and stator coils 38, axially oriented stator coil open channels 48 (fig. 5 and 7) are formed between the teeth 34. The plastic used to overmold the stator and create housing 20 is Rynite polyethylene terephthalate (available from DuPont) or any other plastic material having similar molding and heat transfer characteristics.

A ferrite rotor 62 is mounted on the shaft 56. The shaft is then mounted on bearings 58 to rotate the rotor and shaft within the opening 28 of the stator 30 (fig. 7 and 9). An impeller fan 60 with impeller fan blades 61 is attached to the shaft 56 such that it rotates with the shaft 56 and rotor 62.

The electronic controller 22 controls energization of the coils 38 of the stator 30 to generate a rotating magnetic field that interacts with a permanent magnet comprising a portion of the rotor 62 to produce rotation of the rotor 62. Thus, the electronic controller 22 generates heat that must be dissipated from the EC motor 10. In addition, energizing the electromagnetic stator coils 38 to generate a rotating magnetic field also generates heat that must be dissipated from the inner rotor EC motor 10.

To handle the heat generated by the electronic controller 22 and the stator coils 38, the inner rotor EC motor 10 has an air management system that includes an impeller fan 60, an air inlet 44, radially oriented air passages 46, axially oriented stator cooling passages 48 in the stator 30, and an air outlet 50 in the right end portion 12 of the housing 20. The radially oriented air passage 46 is routed adjacent the cylindrical controller housing 14 and thus adjacent the electronic controller 22. The radially oriented air passages 46 facilitate heat dissipation from the electronic controller 22 proximate to the electronic controller 22. Likewise, axially oriented open cooling channels 48 pass directly through the stator 30, adjacent to the stator coils 38 and between the stator coils 38. In operation, ambient air is drawn into the air intake 44 and through the radially oriented air passage 46 by the impeller fan 60. The air is then discharged from the impeller fan through the axially oriented cooling passage 48 and out the air outlet 50. As best shown in fig. 6, the impeller fan blades 61 of the impeller fan 60 are planar. As a result, air flows from the air inlet 44 to the air outlet 50 regardless of the direction of rotation of the impeller fan 60. Although the air management system 42 of the present invention has been described with respect to an inner rotor EC motor 10, the principles of operation of the air management system 42 are equally applicable to other electric motors.

Turning to fig. 12 and 13, the ferrite rotor 62 has a bushing 64 attached to the shaft 56. The bushing 64 supports 10 silicon steel laminations 66 that are evenly spaced around the outer circumference 63 of the rotor 62. Rectangular shaped permanent ferrite magnets 70 are positioned in the gaps between adjacent steel laminations 66 and slightly recessed from the outer circumference 63 of the rotor 62. Wedge-shaped permanent ferrite magnets 68 are positioned radially between the silicon steel laminations 66 and the bushing 64 and are circumferentially spaced from one another.

Turning to fig. 14A and 14B, the ferrite rotor 62 is optimized using Maxwell 2D FEA software. The width and length of the rectangular magnet 70 are varied to maximize torque output. The width of the rectangular magnet 70 is first set, and then the maximum length of the rectangular magnet is determined so that the rectangular magnet fits in the rotor without the magnets interfering with each other (see fig. 14A and 14B). The area of each configuration was calculated and the maximum area was selected (see table 1).

TABLE 1

Subsequently, the outer radius 65 of the wedge-shaped magnet 68 is increased to maximize torque output. Any increase in the magnet material in the rotor will thus reduce performance. The rotor 62 requires some region above the wedge-shaped magnets 68 to have protrusions (ferromagnetism). Increasing the radius of wedge-shaped magnet 68 (fig. 15B and 15A) will decrease the amount of this protrusion, thereby decreasing torque output.

Fig. 16 shows an alternative rotor embodiment, namely a neodymium-ferrite rotor 74 for an inner rotor EC motor 10. The neodymium-ferrite rotor 74 has a center bushing 76 attached to the shaft 56 of the inner rotor EC motor 10. The bushing 76 supports 10 silicon steel laminations 78 that are evenly spaced around the outer circumference 75. Rectangular-shaped permanent neodymium magnets 82 are positioned in the gaps between adjacent steel laminations 78, circumferentially spaced from one another, and slightly recessed from the outer circumference 75. Wedge-shaped permanent ferrite magnets 80 are positioned radially between the silicon steel laminations 78 and the bushings 76 and are circumferentially spaced from one another. The outer radius 84 of the wedge-shaped permanent ferrite magnet 80 is in contact with the silicon steel laminations 78 and the inner radius 86 conforms to the circumference of the bushing 76. Each wedge-shaped ferrite magnet 80 has a step 88 on each side between the outer radius 84 and the inner radius 86. Adjacent steps 88 between two adjacent wedge-shaped ferrite magnets 80 create a recess that accommodates the inner end 90 of each rectangular neodymium magnet 82.

Referring to fig. 17A and 17B, the neodymium-ferrite rotor 74 includes alternating permanent neodymium magnets 82 and silicon steel laminations 78. The neodymium-ferrite rotor 74 in fig. 17A and 17B is optimized by modeling the neodymium-ferrite rotor 74 and reducing the thickness of the rectangular neodymium magnet 82 until performance drops below a target performance.

Referring to fig. 18, the inner permanent magnet spoke rotor 74 is then simulated using less magnet material for the rectangular neodymium magnet 82 than the rotor 74 shown in fig. 17A and 17B. An air gap 92 is added between the rectangular neodymium magnets 82 to reduce magnetic leakage and thereby improve performance.

Referring to fig. 19A-19D, the length of the spoke rectangular neodymium magnet 82 is then reduced until performance drops below the target performance. The air gap 92 between the neodymium magnets 82 is then filled with wedge-shaped ferrite magnets 80, which improves performance.

Referring to fig. 20, the inner and outer radii of the ferrite magnets 80 are varied to maximize performance of the neodymium ferrite rotor 74 such that the optimal combination of neodymium magnets 82 and ferrite magnets 82 minimizes cost and maximizes performance. The ferrite rotor 62 is less costly than the neodymium-ferrite rotor 74 because the price per kilogram of neodymium is an order of magnitude more expensive than ferrite. Neodymium also has a higher magnetic flux than ferrite. For these reasons, the neodymium-ferrite rotor 74 is more efficient than the ferrite rotor 62, but is also more costly than the ferrite rotor 62.

A second embodiment of an electronically commutated DC motor is an outer rotor EC motor 110. An outer rotor EC motor 110 according to the present invention is shown in fig. 21 to 31. The outer rotor EC motor 110 has a housing that includes a cylindrical controller housing 112 and a cylindrical stator case 150. The stationary stator 130 is attached to the cylindrical controller housing 112 and the cylindrical stator case 130 by means of connection tabs 114, case shims 154, stator posts 140 (fig. 30) and connector screws 156 threaded into the stator posts 140. The electronic controller 116 is mounted inside the cylindrical controller housing 112. The heat sink 120 is thermally attached to the electronic controller 116, thereby dissipating heat generated by electronics within the electronic controller 116 (fig. 21, 23, 25, 26, and 27). An electrical connector 118 is provided to connect power and control signals to the outer rotor DC motor 110.

Referring to fig. 23, 24, 25 and 30, the stationary stator 130 has a bushing 132, with a stator bearing 144 fitted into the bushing 132. The ribs 142 radiate from the bushing 132 and terminate at their distal ends with stator posts 140, which stator posts 140 serve to connect the stator 132 to the cylindrical controller housing 112 and stator case 150 as previously described. In the particular embodiment shown in fig. 30, the stator 130 has 12 individual stator silicon steel lamination teeth 134. A gap or air channel 138 circumferentially separates each tooth 134. Each tooth 134 (not shown) is wound with an electrically conductive electromagnetic coil to generate a rotating electromagnetic force as is commonly understood in the art. The stator 130 has a plastic overmolded structure 136, which plastic overmolded structure 136 covers the teeth 134 and the electromagnetic coil except for the outer convex tooth surface 146. The overmolded structure 136 further leaves gaps or air channels 138 between the individual teeth 134. As previously described, the plastic used for the overmolded structure is Rynite.

Rotor 160 includes a bushing 164 to which rotor shaft 166 is secured. Rotor shaft 166 is mounted for rotation in stator bearing 144 (fig. 31). An end cap 168 extends from the bushing 164 and terminates at the cylindrical rotor housing 162. The end cap 168 has reinforcing ribs 170 on its outer surface. The inner surface of the end cap 168 includes an impeller fan 174 (fig. 29). Impeller fan 174 includes a planar radially extending inner fan blade 176 and a planar radially extending outer fan blade 178. The cylindrical rotor housing 162 has a plurality of air outlets 172 spaced around its periphery. A series of spaced apart permanent magnets 182 are attached around the inner surface of the cylindrical rotor housing and are axially offset from the air outlet 172.

In operation, the rotating magnetic field generated by the teeth 134 of the stator 130 interacts with the permanent magnets 182 of the rotor 160, causing the rotor 160 to rotate on the rotor shaft 166 within the bearing 144. As the rotor 160 rotates, the fan blades 176 and 178 draw ambient air into the shroud air intake opening 152, through the radiator 120, through the stator air passage 138 and into the impeller fan 174. As shown by line 180 in FIG. 31, fan blades 176 and 178 then exhaust air through air outlet 172. As a result, ambient air first dissipates heat from the heat sink 120, thereby maintaining cooling of the electronics of the electronic controller 116. Next, ambient air passes through the stator air channels 138, thereby maintaining cooling of the stator 130. Because the fan blades 176 and 178 are planar rather than curved, ambient air is drawn into the shroud air intake opening 152, through the stator air passages 138, and out through the air outlet 172, regardless of the direction of rotation of the fan 174.

Referring to fig. 32-37C, the electronic controller 22 is encapsulated in an epoxy 220 to stabilize the components 204 mounted to the printed circuit board 202 and to aid in dissipating heat from those components 204 (fig. 37A). Fig. 32 shows a bottom precision master mold 211 and fig. 34 shows a top precision master mold 209. The precision female molds 211 and 209 are formed of a rigid plastic such as polylactic acid (PLA). In the development process of the present invention, the master molds 211 and 209 are created by 3D printing using PLA. However, in a production environment, the precision female molds 211 and 209 are typically made of steel.

Fig. 33 shows a bottom silicone mold 212 and fig. 35 shows a top silicone mold 210. The bottom silicone mold 212 is created by casting silicone around the bottom precision master mold 211 shown in fig. 32. The top silicone mold 210 is created by casting silicone around the top precision master mold 209 shown in fig. 34. The bottom silicone mold 212 and the top silicone mold 210 together form a two-part silicone mold 208 (fig. 37B). Silica gel is a versatile two-part silica gel for epoxy casting.

Fig. 37A to 37C illustrate a process of packaging the electronic controller 22 and its printed circuit board 202 and heat sink 206. In order to properly encapsulate the electronic controller 22, it is necessary to encapsulate only those portions that need to be encapsulated, such as the printed circuit board 202 and its components 204, while leaving the other components of the controller 22 free of epoxy coating. Leaving the heat sink 206 of the controller 22 free of an epoxy coating. The area of the printed circuit board 202 not covered by epoxy is at the connection to the motor and the negative temperature coefficient thermistor. The negative temperature coefficient thermistor is designed to heat up to reduce the on-line resistance, so covering it with epoxy reduces the efficiency of the controller 22. The volume of the printed circuit board 202 adjacent to the absence of the component 204 is also free of an epoxy coating to minimize material usage and save costs.

To selectively coat controller 22 with epoxy 220, silicone mold 208 has a void 224 that accommodates printed circuit board 202 and leaves a layer of epoxy 220 around printed circuit board 202 when needed. In the case where a component on the controller 22, such as the heat sink 206, is devoid of the epoxy 220, the void 224 only accommodates the portion itself, leaving no room for the epoxy 220.

The shape of the hardened epoxy 220 is determined by the silicone mold 208. The shape of the silicone mold 208 is determined by the shape of the controller 22 and the minimum thickness required to cover the printed circuit board assembly 204.

The process of packaging electronic controller 22 begins by placing bottom silicone mold 212 into supporting bottom exoskeleton 218. Fig. 37A shows the insertion of the electronic controller 22 into the bottom portion 212 of the two-part silicone mold 208. Then, as shown in fig. 37B, top portion 210 of silicone mold 208 is closed over bottom portion 212 of silicone mold 208 and top 217 of exoskeleton 219 is closed over bottom 218 of exoskeleton 219. In particular, when the silicone mold portions 212 and 210 are closed together (fig. 37B), a void 224 is created adjacent the component to be encapsulated, while no void exists adjacent other components to remain unencapsulated. Once the silicone mold sections 210 and 212 are closed, the silicone mold 208 is positioned in an exoskeleton 219 that includes a top exoskeleton 217 and a bottom exoskeleton 218. Epoxy 220 is injected into the channel 222 and void 224 created by the two-part silicone mold 208 using an injector 214 that removes most of the air from the epoxy. Suitable syringes 214 include an M20 dispenser manufactured by guangzhou Mingkang, guangdong province, china.

Once the injection has been completed, the silicone mold 208 is negatively pressurized and then heated. The negative pressure in the silicone mold 208, which is near full vacuum, removes air bubbles from the epoxy prior to the thermal curing process. The epoxy resin is cured at a high temperature of 60-70 ℃ for 1.5-2.0 hours. Once the epoxy is cured, the exoskeleton 219, silicone mold 208 are separated, and the encapsulated controller 22 is removed from the silicone mold 208. The epoxy used to encapsulate the electronic controller 22 is Guangzhou Baoshi electronic material 55225A/B.

Although the invention has been described with reference to preferred embodiments, it is to be understood that variations and modifications can be effected within the spirit and scope of the invention as described herein and as described in the appended claims.

Claims (4)

1. A method of encapsulating an electronic controller with epoxy, the electronic controller being located in an EC motor, wherein certain portions of the electronic controller are encapsulated and other portions of the electronic controller are not encapsulated, the method comprising the steps of:

a. Creating a two-part silicone mold having a first mold part and a second mold part, wherein each mold part, when joined together, creates a void for surrounding and encapsulating the certain parts and does not create a void for surrounding other parts not to be encapsulated;

b. injecting the epoxy into the void for encapsulating the portion while leaving the other portion free of the epoxy; and

C. subjecting the silicone mold, the epoxy, and the electronic controller to negative pressure to remove air bubbles from the epoxy and heat to cure the epoxy.

2. The method of claim 1, wherein the silicone mold is supported by an exoskeleton during the injecting and subjecting steps.

3. The method of claim 1, wherein the silicone mold is created by 3D printing.

4. The method of claim 1, wherein the epoxy resin is subjected to the negative pressure and then cured at a temperature between 60-70 ℃ for 1.5-2.0 hours.