JP4853652B2 - Axial air gap type electric motor - Google Patents

Description

  The present invention relates to an axial air gap type electric motor in which a stator and a rotor are arranged to face each other along the axial direction of a motor output shaft, and more specifically, a bracket for housing the stator and the rotor, and a lid cover attached to the bracket. And a seal structure.

  An axial air gap type electric motor is an electric motor in which a rotor (rotor) is arranged oppositely with a predetermined gap on one or both sides of a stator (stator), and is a radial gap type electric motor such as an inner rotor type. Compared to the above, there is a feature that the thickness in the direction of the rotation axis can be reduced, that is, flattened.

  The motor mechanism including the stator and the rotor is housed in a cylindrical bracket and lid covers are attached to both ends thereof. At this time, in order to prevent water and the like from entering the bracket, Need to be sealed.

  As an example of this sealing process, in Patent Document 1, for example, a space formed between the abutting surfaces of the bracket and the lid cover is filled with a sealing agent, and the bracket is crimped, so that the sealing agent is evenly distributed in the space. Spread and seal the inside of the bracket.

  However, the application of this type of sealing process to an axial air gap type motor has the following problems. That is, the axial air gap type electric motor is applied to the periphery of the bracket when the lid cover is attached to the bracket because there is a rotation space of the rotor just inside the inner peripheral surface of the bracket as shown in Patent Document 2. There is a risk that an excess of the sealing agent leaks into the rotating space.

  In addition, the axial air gap type electric motor has recently been attracting attention as a power source for a bicycle with an electric assist because of its small size and high output, and since this type of electric motor is used outdoors, it is particularly highly waterproof and dustproof. Is required.

Japanese Patent No. 3168167 JP 2007-6699 A

  Accordingly, in order to solve the above-described problems, the present invention is to provide an axial air gap type electric motor having a sealing structure capable of reliably sealing between a bracket and a lid cover.

In order to achieve the above-described object, the present invention has several features described below. According to the first aspect of the present invention, the stator and the rotor are disposed in a state of being opposed to each other with a predetermined gap along the axial direction of the output shaft, and a lid cover is attached to the open end of the bracket. In the Achill air gap type electric motor, a sealing agent for sealing between the bracket and the lid cover is filled in the open end on which the terminal pin for energizing the stator of the bracket is projected. A first seal groove and a second seal groove for sealing the periphery of the terminal pin, and the second seal groove is disposed so as to surround the periphery of the terminal pin. A part of the second seal groove is formed with an escape groove for allowing excess sealant overflowing from the second seal groove when the cover is covered to the outside of the second seal groove. The escape groove is formed on the second seal groove so that an excess of the sealant overflowing from the second seal groove does not flow into the rotor storage space formed on the open end side of the bracket. It is characterized by being arranged on one or both sides in the circumferential direction .

The invention according to claim 2, Oite to the claim 1, the outer circumference of the second seal groove is characterized in that recesses for receiving the sealing agent flowing out from the relief groove.

The invention according to claim 3, Oite to the claim 1 or 2, in the lid cover is characterized in that the protrusions to be inserted along said second seal groove.

  According to the first aspect of the present invention, the first seal groove for filling the sealant between the bracket and the lid cover and the second seal groove for sealing the periphery of the terminal pin are provided. The space between the lid cover and the lid cover can be surely sealed.

Further, in one or both of the circumferential direction of the second seal groove, by providing the escaping groove for releasing excess sealant, to reliably prevent the sealant from flowing into the low data storage portion of the bracket be able to.

According to the invention described in claim 2, by a recess for receiving a sealant discharged from the escape groove in the outer circumference of the second seal groove is provided, it is received reliably excess sealant in the recess Can do.

According to the invention described in claim 3 , by providing the convex portion inserted into the second seal groove on the lid cover side, the sealing agent filled in the second seal groove is evenly distributed in the second seal groove. Not only can it be distributed, but also the adhesion is improved.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 is an exploded cross-sectional view of an axial air gap type electric motor according to an embodiment of the present invention, FIG. 2 is a perspective view of the bracket, and FIG. 3 is a front view of the bracket viewed from the axial direction.

  As shown in FIGS. 1 and 2, this axial air gap type electric motor 1 is opposed to a stator 2 formed in a disk shape and a predetermined gap (air gap) on both side surfaces of the stator 2. A pair of rotors 3 and 3 is provided.

  In the stator 2, a plurality of core members 21 are annularly arranged around the axis of the rotor output shaft 4, and these are integrally connected to form a disk-shaped stator 2. A coil (not shown) is wound around each core member in multiple layers, and these are connected in a predetermined order.

  The rotors 3 and 3 include a disk-shaped rotor back yoke 31 made of an electromagnetic steel plate and the like, and a rotor magnet 32 attached to the rotor back yoke 31 at a predetermined interval in the circumferential direction. In this example, the rotors 3 and 3 are disposed on both the left and right sides of the stator 2, but only one of them may be provided.

  A rotor output shaft 4 for taking out the rotational force of the rotors 3 and 3 is coaxially attached to the center of the rotors 3 and 3. In this example, the rotor output shaft 4 shares the two rotors 3, 3, but may be a two-output shaft type in which each rotor 3, 3 has a rotor output shaft. Furthermore, it is good also as a shaft-less type | mold which does not have the rotor output shaft 4, but supports the rotors 3 and 3 directly with respect to the stator 2 via a radial ball bearing.

  The stator 2 is integrally formed with the bracket 100 by insert molding by pouring molten resin into the mold. That is, in this example, the bracket 100 is integral with the stator 2. The bracket 100 is made of synthetic resin such as engineering plastic, for example, and is formed so as to leave only the portion of the tooth surface 22 of the stator 2 exposed.

  A bearing 5 is disposed at the center of the stator 2. In this example, the bearing portion 5 has a pair of radial ball bearings 5, 5 whose inner ring is press-fitted into the rotor output shaft 4, and the outer ring side is a shaft insertion hole formed at the center of the bracket 100 of the stator 2. 101 is embedded. In the present invention, the configuration of the bearing portion 5 may be arbitrary.

  Three screw holes 102 for fixing a first cover 210 (to be described later) to the bracket 100 are provided on the outer peripheral surface of the bracket 100 in this example. The screw hole 102 can be arbitrarily changed according to the specification.

  At both ends of the bracket 100, first and second rotor housing recesses 110 and 120 in which the rotors 3 and 3 are rotatably housed are provided. Teeth surfaces 22 of the core members 21 of the stator 2 are exposed in an annular shape at the bottoms of the first and second rotor housing recesses 110 and 120.

  A cylindrical portion 140 to which the first lid cover 210 is attached is provided at one end portion (right end portion in FIG. 1) of the bracket 100. As shown in FIG. 4, the inner peripheral side of the cylindrical portion 140 is used as the first rotor housing recess 110 described above.

  A first lid cover 210 is attached along the outer peripheral surface 141 of the cylindrical portion 140. Referring to FIGS. 1 and 4, first lid cover 210 is formed of a synthetic resin molded product such as engineering plastic, and is formed in a disc dome shape so as to close the end of bracket 100.

  The center of the first lid cover 210 is annularly recessed, and the side wall inner surface 211 abuts along the cylindrical portion 140 of the bracket 100. Three fixing holes 213 corresponding to the screw holes 102 provided on the outer periphery of the bracket 100 are provided on the outer periphery of the first lid cover 210.

  On the open end side of the side wall inner surface 211, a step surface 212 having a diameter slightly larger than the inner diameter of the side wall inner surface 211 is provided, so that when the first lid cover 210 is attached to the bracket 100, the cylindrical portion 140 is provided. A space is formed between the outer peripheral surface 141 and the side wall inner surface 212.

  According to this, as shown in FIG. 5, after applying the sealing agent S1 to the base portion of the cylindrical portion 140, the first lid cover 210 is fitted along the cylindrical portion 140, so that the sealing agent S1 is placed on the outer peripheral surface. 141, the space between the side wall inner surface 212 and the side wall inner surface 212 is tightly filled, and the space between the bracket 100 and the first lid cover 210 can be reliably sealed.

  Referring again to FIGS. 1 to 3, an annular mounting surface 150 for mounting the second lid cover 220 is provided on the other end side (left end side in FIG. 1) of the bracket 100. The annular mounting surface 150 is annularly formed with a specified width between the inner peripheral surface of the second rotor housing recess 120 and the outer peripheral surface of the bracket 100.

  On the outer peripheral side of the annular mounting surface 150, an outer rib 155 that abuts along a second lid cover 220, which will be described later, is formed in an annular shape. Is formed.

  As shown in FIGS. 2 and 3, the upper surface of the outer rib 155 is provided with a first seal groove 160 into which a sealing agent S2 (see FIG. 6) for hermetically sealing with the second lid cover 220 is poured. It has been. In this example, the first seal groove 160 is a semicircular groove cut out inward from the upper surface, and is formed in an annular shape along the outer rib 155.

  As shown in FIG. 7, the stepped surface 156 of the annular mounting surface 150 is integrally provided with a terminal block 152 that supports terminal pins 151 for supplying power to the stator 2 from an external power source (not shown). In this example, the terminal pin 151 and the terminal block 152 are provided at three places for a three-phase brushless DC motor, but the number may be other than this.

  The annular mounting surface 150 is further provided with a second seal groove 170 for independently sealing the periphery of each terminal block 152. The second seal groove 170 is formed so as to surround each terminal block 152, and a part (outer side in the radial direction) of the second seal groove 170 communicates with the first seal groove 160.

  On the outer peripheral side of the second seal groove 170, a leakage prevention wall 180 for preventing leakage of the sealing agent S2 is provided. The leakage prevention wall 180 is formed in a U shape with the open side facing the outside (the first seal groove 160 side) when the bracket 100 is viewed from the axial direction (the direction of FIG. 3). The leakage prevention wall 180 is erected from the step surface 156 so that its top end is flush with the outer rib 155.

  According to this, the space formed between the outer rib 155 and the leakage prevention wall 180 functions as the second seal groove 170, so that the seal agent S <b> 2 filled in the second seal groove 170 is second. It does not leak to the rotor storage recess 120 side (in the radial direction).

The leakage prevention wall 180, when fitted with a second lid cover 220 to the bracket 100, that have escape grooves 181 for releasing the excess of the second sealing agent S2, extruded by the lid cover 220 is formed.

  The relief grooves 181 are provided at both ends in the circumferential direction of the leakage prevention wall 180, and even if surplus is generated in the sealing agent S 2, the excess sealing agent is placed in the left and right sides of the leakage prevention wall 180. By letting it escape, the sealing agent S2 is prevented from flowing into the second rotor housing recess 120.

It is preferable that concave portions 153 for receiving the leaked sealant are provided on both the left and right sides of each terminal block 152 (the outlet side of the escape groove 181). According to this, the surplus of the sealing agent S2 can be escaped and can be avoided in the recess 153 through the groove 181, and the sealing agent S2 can be reliably prevented from flowing into the second rotor housing recess 120.

  As shown in FIG. 7, in this example, a boss 154 for positioning the position of the second lid cover 220 is protruded from a part of the recess 153 when the second lid cover 220 is attached. The boss 154 is an optional item in the present invention.

  Next, the second lid cover 220 will be described with reference to FIGS. 1 and 8 together. The second lid cover 220 is made of a synthetic resin molded product such as engineering plastic, and is formed in a disk shape larger in diameter than the bracket 100.

  A shaft extraction hole 221 for extracting the rotor output shaft 4 to the outside is provided in the center of the second lid cover 220. On the inner surface of one side (the right end in FIG. 1) of the second lid cover 220, a seal surface 222 is formed that abuts along the open surface (the left end in FIG. 1) on the other end side of the bracket 100.

  As shown in FIG. 1, the seal surface 222 includes an annular recess that is recessed inward from the inner surface of the second lid cover 220. The inner wall surface of the seal surface 222 is in contact with the outer peripheral surface of the bracket 100.

  The second lid cover 220 further includes three pin lead-out holes 223 for pulling out terminal pins 151 protruding from the annular mounting surface 150 of the bracket 100 to the outside of the bracket 100 in accordance with the number of terminal pins 151. Is provided.

  The second lid cover 220 is formed with a notch groove 224 so as to surround both ends of each pin lead-out hole 223 in the circumferential direction and the inner side in the radial direction. The notch groove 224 is provided at a position facing the leakage prevention wall 180 of the annular mounting surface 150. According to this, as shown in FIGS. 9A and 9B, the leakage prevention wall 180 is inserted into the notch groove 224 by attaching the second lid cover 220 along the annular attachment surface 150.

  Also, by providing the notch groove 224, a rib 225 that enters the second seal groove 170 is formed between each pin lead-out hole 223 and the notch groove 224, and this rib 225 is formed in the second seal groove 170. The sealing agent S <b> 2 filled in the second seal groove 170 is brought into close contact along the second seal groove 170 by being inserted along the second seal groove 170.

  In this example, the second lid cover 220 is provided with a guide hole 226 for guiding a positioning rib 154 protruding from the annular mounting surface 150 of the bracket 100. The positions and shapes of the rib 154 and the guide hole 226 can be arbitrarily changed according to the specifications.

  Next, an example of a sealing procedure for the bracket 100 and the lid covers 210 and 220 will be described with reference to FIGS. In the following description, it is assumed that the stator 2 and the rotor 3 are incorporated in the bracket 100 by a predetermined method in advance.

  First, as shown in FIG. 4, the sealing agent S <b> 1 is applied along the root of the cylindrical portion 140 of the bracket 100. In this example, a curable sealing agent such as a silicone-based liquid gasket is used as the sealing agent S1.

  After applying the sealing agent S <b> 1, the first lid cover 210 is attached along the cylindrical portion 140 of the bracket 100, and pushed into a position where the first lid cover 210 contacts the terminal end of the cylindrical portion 140.

  As a result, the sealing agent S <b> 1 is swept into a space formed between the outer peripheral surface of the cylindrical portion 140 of the bracket 100 and the side wall inner surface 212 of the first lid cover 210. Thereby, the space between the first lid cover 210 and the bracket 100 is reliably sealed.

  Next, the other open surface is sealed. As shown in FIG. 6, first, the sealant S <b> 2 is filled along the first seal groove 160 and the second seal groove 170. Next, after aligning the second lid cover 220 at a position where the rib 154 and the guide hole 226 coincide with each other, the second lid cover 220 is put on the annular mounting surface 150.

  At this time, by pressing the second lid cover 220 toward the annular mounting surface 150, the ribs 225 of the second lid cover 220 enter the second seal groove 170 as shown in FIGS. 9A and 9B. The sealant S2 in the second seal groove 170 is crushed. As a result, the sealing agent S2 is evenly distributed in the base 2 seal groove 170.

  At this time, the surplus of the sealant S2 that does not fit in the second seal groove 170 is discharged to the recesses 153 provided on both sides of the second seal groove 170 via the escape groove 181 of the leakage prevention wall 180.

  In this example, the plate-like second lid cover 220 is illustrated as an engagement partner of the other open surface (annular mounting surface 150). However, other than this, for example, a torque detection unit or control of a bicycle with an electric assist In the case where the axial air gap type motor is directly attached to a part of the casing of the drive unit in which the circuit is housed, the engaging surface of the casing corresponds to the mounting surface of the lid cover. Included in the invention.

  Finally, the bracket 100 and the first and second lid covers 210 and 220 are integrally fixed to the motor mounting portion (not shown) with bolts through the screw holes 102 and the fixing holes 213. Through the series of sealing steps described above, the inside of the bracket 100 is reliably sealed from the outside.

  In this example, the bracket 100 is integrally formed by insert molding the stator 2 in a mold, but the bracket 100 is molded as a separate body, and the stator 2 and the rotor 3 are accommodated therein. May be.

  In this example, the axial air gap type electric motor 1 is exemplified as a method of using it as a power source for a bicycle with an electric assist. If it is provided, the form of use is arbitrary.

The exploded sectional view of the axial air gap type electric motor concerning one embodiment of the present invention. The perspective view of the bracket of the said axial air gap type electric motor. The front view of the terminal pin installation surface of a bracket. The disassembled perspective view of a bracket and a 1st cover. The partial expanded sectional view of the state which attached the 1st cover to the bracket. The disassembled perspective view of a bracket and a 2nd cover cover. The partial expansion perspective view of the annular attachment surface in which the terminal pin was installed. The front view which looked at the 2nd cover from the bracket opposing surface side. (A) Sectional drawing of meshing with bracket in line AA in FIG. 7, (b) Cross sectional view of meshing with bracket in line BB in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axial air gap type motor 2 Stator 21 Stator core 22 Teeth surface 3, 3 Rotor 31 Rotor back yoke 32 Rotor magnet 4 Rotor output shaft 5 Radial ball bearing 100 Bracket 101 Shaft insertion hole 102 Screw hole 110 First rotor housing recess 120 Second Rotor housing recess 140 Cylindrical portion 150 Annular mounting surface 151 Terminal pin 152 Terminal block 153 Recess 160 First seal groove 170 Second seal groove 180 Leakage prevention wall 181 Escape groove S1, S2 Sealing agent

Claims (3)

In an air gap type electric motor in which a stator and a rotor are arranged opposite to each other with a predetermined gap along the axial direction of the output shaft and housed in a bracket, and a lid cover is attached to the open end of the bracket,
A first seal groove filled with a sealant for sealing between the bracket and the lid cover at the open end where a terminal pin for energizing the stator of the bracket is provided, and A second seal groove for sealing the periphery of the terminal pin is provided ,
The second seal groove is disposed so as to surround the periphery of the terminal pin, and a part of the second seal groove overflows from the second seal groove when the lid cover is covered. An escape groove is formed for allowing an excess of the agent to escape outside the second seal groove,
The escape groove is provided in a circumferential direction of the second seal groove so that an excess of the sealant overflowing from the second seal groove does not flow into the rotor storage space formed on the open end side of the bracket. An axial air gap type electric motor characterized by being arranged on one or both side surfaces . 2. The axial air gap type electric motor according to claim 1, wherein a concave portion for receiving the sealant that has come out of the escape groove is provided on an outer periphery of the second seal groove. The axial air gap type electric motor according to claim 1 or 2, wherein the lid cover is provided with a convex portion inserted along the second seal groove.

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