CN113572300A

CN113572300A - Electric motor

Info

Publication number: CN113572300A
Application number: CN202110453795.1A
Authority: CN
Inventors: 中山裕次
Original assignee: Nidec Sankyo Corp
Current assignee: Nidec Instruments Corp
Priority date: 2020-04-28
Filing date: 2021-04-26
Publication date: 2021-10-29
Anticipated expiration: 2041-04-26
Also published as: CN113572300B; JP2021175312A; JP7385524B2

Abstract

A motor includes a motor main body, a motor case accommodating the motor main body, and a shield wire drawn out of the motor case, and can improve the appearance even if the shield wire is prevented from being drawn out when a tensile force acts on the shield wire. In the motor, a shielding material folding part (8c) for folding back a shielding material (37) to the side of the central core wire covering part is formed at the boundary part of the central core wire exposed part (8a) and the central core wire covering part (8b) of the shielding wire (8). An insertion hole (43a) of a bush (43) attached to a motor housing is provided with a small-diameter inner peripheral surface portion (43b) on which a middle core wire covering portion (8b) is disposed and a large-diameter inner peripheral surface portion (43c) on which a shield material folded portion (8c) is disposed. The shield material folded portion (8c) is adhesively fixed to the large-diameter inner peripheral surface portion (43c) in a state of being in contact with a step surface (43d) formed at a boundary portion between the large-diameter inner peripheral surface portion (43c) and the small-diameter inner peripheral surface portion (43 b).

Description

Electric motor

Technical Field

The present invention relates to a motor including a shield wire drawn out of a motor case.

Background

Conventionally, there is known an electric motor including: a motor main body having a rotor and a stator; and a motor housing accommodating the motor main body (see, for example, patent document 1). The motor described in patent document 1 includes an encoder for detecting a rotational speed or a rotational position of a rotor. The encoder includes: a sensor magnet mounted on the rotor; a magnetic induction element disposed opposite to the sensor magnet; and a sensor substrate on which the magnetic induction element is mounted. The sensor output line is connected to the sensor substrate. The sensor output line is, for example, a shielded line including a center core wire, a shielding material covering the center core wire, and an insulating film covering the shielding material.

In the motor described in patent document 1, a motor housing includes: a cylindrical housing; a first bearing holder disposed on the opposite side of the cylindrical housing from the output side; and a second bearing holder disposed on the output side of the cylindrical housing. An encoder cover for accommodating the encoder is mounted on the opposite side of the first bearing holder from the output side. The encoder cover is provided with a notch portion, and a gap is formed between the encoder cover and the first bearing holder through the notch portion. A bushing is interposed in the gap. The sensor output line is wound through the bushing, and the sensor output line passing through the bushing is led out to the outside in the radial direction of the motor.

In the motor described in patent document 1, a wire fixing portion for fixing the sensor output wire to the outside of the motor housing is formed in the first bearing holder, and the sensor output wire led out to the outside of the encoder cover through the bush is fixed to the wire fixing portion. In the motor described in patent document 1, the sensor output wire is fixed to the wire fixing portion, thereby preventing the sensor output wire from being pulled out when a pulling force for pulling out the sensor output wire acts on the sensor output wire. That is, in the motor described in patent document 1, the sensor output line is fixed to the wiring fixing portion, thereby preventing the connection portion between the sensor output line and the sensor substrate from being damaged when a tensile force acts on the sensor output line.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-9570

Disclosure of Invention

Technical problem to be solved by the invention

In the motor described in patent document 1, the sensor output line is fixed to a wiring fixing portion disposed outside the motor case, and the fixing portion of the sensor output line appears in the appearance of the motor. Therefore, in the case of the motor described in patent document 1, the appearance of the motor is deteriorated.

Accordingly, an object of the present invention is to provide a motor including a motor main body portion having a rotor and a stator, a motor case accommodating the motor main body portion, and a shield wire drawn out to the outside of the motor case, the motor being capable of improving the appearance even if the shield wire is prevented from being drawn out when a tensile force acts on the shield wire.

Technical scheme for solving technical problem

In order to solve the above problem, an electric motor according to the present invention includes: a motor main body portion having a rotor and a stator; a motor case that houses a motor main body portion; a detection mechanism housed in the motor case; a shielded wire drawn out from the detection mechanism toward an outside of the motor case; and a rubber bush for preventing liquid from penetrating into the motor case, the shielded wire including a center core wire, a shielding material covering the center core wire, and an insulating coating covering the shielding material, the shielded wire being formed with a shielded material and a center core wire covering portion in which the insulating coating is removed to expose a center core wire exposed portion of the center core wire and the center core wire covered with the shielding material and the insulating coating, a shielding material folded portion formed at a boundary portion between the center core wire exposed portion and the center core wire covering portion, the shielding material folded back to an outer peripheral surface of the insulating coating on the center core wire covering portion side, the center core wire exposed portion being disposed inside the motor case, the bush being attached to the motor case, the bush being formed with an insertion hole through which the shielded wire is inserted, the insertion hole including a small-diameter inner peripheral surface portion and a large-diameter inner peripheral surface portion, the small-diameter inner peripheral surface portion being disposed with the center core wire covering portion, the large diameter inner peripheral surface portion is provided with a shield material folded portion, the inner diameter of the large diameter inner peripheral surface portion is larger than that of the small diameter inner peripheral surface portion, the small diameter inner peripheral surface portion is arranged on the outer side of the motor housing, the large diameter inner peripheral surface portion is arranged on the inner side of the motor housing, a step surface in which the shield material folded portion is in contact is formed on the boundary portion between the large diameter inner peripheral surface portion and the small diameter inner peripheral surface portion, and the shield material folded portion is bonded and fixed to the large diameter inner peripheral surface portion.

In the motor of the present invention, a shield material folded portion where the shield material is folded back to the outer peripheral surface of the insulating film on the side of the core wire covering portion is formed at a boundary portion between the core wire exposed portion and the core wire covering portion of the shield wire. In the present invention, the insertion hole of the bush attached to the motor case includes a small-diameter inner peripheral surface portion on which the center wire covering portion is disposed and a large-diameter inner peripheral surface portion on which the shield material folded portion is disposed, the small-diameter inner peripheral surface portion being disposed on an outer side of the motor case, and the large-diameter inner peripheral surface portion being disposed on an inner side of the motor case. In the present invention, a step surface with which the shield material folded-back portion is brought into contact is formed at a boundary portion between the large-diameter inner peripheral surface portion and the small-diameter inner peripheral surface portion, and the shield material folded-back portion is adhesively fixed to the large-diameter inner peripheral surface portion.

Therefore, in the present invention, the shield wire can be prevented from being pulled out when a tensile force acts on the shield wire by the stepped surface of the bushing attached to the motor case, the shield material folded-back portion of the shield wire, and the adhesive that adhesively fixes the shield material folded-back portion to the large-diameter inner peripheral surface portion of the bushing. In the present invention, the small-diameter inner peripheral surface portion is disposed on the outer side of the motor case, and the large-diameter inner peripheral surface portion is disposed on the inner side of the motor case, so that the portion of the shield material folded portion bonded to the large-diameter inner peripheral surface portion does not appear on the appearance of the motor. Therefore, in the present invention, even if the pulling-out of the shield wire when the pulling force acts on the shield wire can be prevented, the appearance of the motor can be improved. In addition, in the present invention, since the shield material of the shield wire can be used to prevent the pull-out of the shield wire, the structure of the motor can be simplified.

Further, in the present invention, since the shield material folded-back portion is disposed on the large-diameter inner peripheral surface portion of the bush and is fixed by adhesion, the amount of projection of the shield material folded-back portion having a large outer diameter into the motor case can be suppressed. Therefore, in the present invention, the shield material folded-back portion can be disposed inside the motor case even if the disposition space of the shield material folded-back portion is narrowed or the disposition space of the shield material folded-back portion is not provided. Therefore, in the present invention, the influence of the folded-back portion of the shielding material on the assembly of the motor can be reduced in the motor case, and as a result, the assembly of the motor can be easily performed. In addition, in the present invention, since the influence of the folded portion of the shielding material on the constituent parts disposed inside the motor case can be reduced, the degree of freedom in designing the motor can be improved.

In the present invention, it is preferable that the shielding material folded back to the outer peripheral surface of the insulating film in the shielding material folded-back portion is twisted in the circumferential direction of the core wire covering portion. With this configuration, the outer diameter of the shield folded portion can be increased as compared with a case where the shield folded back onto the outer peripheral surface of the insulating film is not twisted in the circumferential direction of the core wire coated portion. Therefore, the difference between the outer diameter of the shield material folded back portion and the outer diameter of the core wire covering portion can be increased, and the contact area between the stepped surface formed in the bush and the shield material folded back portion can be enlarged. As a result, the shield wire can be effectively prevented from being pulled out when a tensile force acts on the shield wire.

In the present invention, for example, the insertion hole is constituted by a small-diameter inner peripheral surface portion and a large-diameter inner peripheral surface portion. In this case, the shape of the insertion hole can be simplified. In the present invention, for example, the core wire coating portion is press-fitted into the small-diameter inner peripheral surface portion.

In the present invention, it is preferable that the shielding material folded-back portion is covered with an adhesive that adhesively fixes the shielding material folded-back portion to the large-diameter inner peripheral surface portion. With this configuration, the shielding material folded back on the outer peripheral surface of the insulating film can be covered with the adhesive, and therefore, the insulating property of the shielding material folded back on the outer peripheral surface of the insulating film can be ensured using the adhesive.

In the present invention, it is preferable that the shielding material folded back on the outer peripheral surface of the insulating film has a tip end directed to the outside of the motor case in the shielding material folded back portion. That is, in the shielding material folded-back portion, the front end of the shielding material folded back on the outer peripheral surface of the insulating film preferably does not face the side of the exposed core wire. With this configuration, the contact between the leading end of the shield material and the core wire can be prevented. Therefore, it is easy to ensure insulation of the shield material and the core wire.

Effects of the invention

As described above, the present invention provides a motor including a motor main body having a rotor and a stator, a motor housing accommodating the motor main body, and a shield wire drawn out to the outside of the motor housing, which can improve the appearance of the motor even when the shield wire is prevented from being drawn out when a tensile force acts on the shield wire.

Drawings

Fig. 1 is a perspective view of a motor according to an embodiment of the present invention.

Fig. 2 is a sectional view of the motor shown in fig. 1.

Fig. 3 is a diagram for explaining the structure of the shield wire and the bushing shown in fig. 2.

Fig. 4 is a perspective view of the shield wire, the cover, and the like shown in fig. 1.

Fig. 5 is an exploded perspective view of the cover, liner, and liner cover shown in fig. 4.

Fig. 6 is an exploded perspective view showing the cover, the bush, and the bush cover shown in fig. 5 from different directions.

Description of the reference numerals

1 … electric motor; 2 … rotor; 3 … stator; 4 … motor body portion; 5 … motor housing; 6 … detection mechanism; 8 … shielded wire; 8a … core wire exposed portion; 8b … core wire coating portion; 8c … a folded back portion of shielding material; 36 … core wire; 37 … shielding material; 38 … insulating film; 39 … adhesive; 43 … a bushing; 43a … insertion hole; 43b … small-diameter inner peripheral surface portion; 43c … large-diameter inner peripheral surface portion; 43d … step surface.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

(integral Structure of Motor)

Fig. 1 is a perspective view of a motor 1 according to an embodiment of the present invention. Fig. 2 is a sectional view of the motor 1 shown in fig. 1.

The motor 1 of the present embodiment is an inner rotor type motor. The motor 1 includes: a motor main body 4 having a rotor 2 and a stator 3; a motor case 5 accommodating the motor main body portion 4; and a detection mechanism 6 for detecting the rotational speed and rotational position of the rotor 2. The motor 1 further includes a power supply line 7 for supplying power to the motor main body 4 and a shield line 8 connected to the detection mechanism 6.

The rotor 2 includes a rotating shaft 11 and a driving magnet 12 fixed to the rotating shaft 11. The output-side end of the rotary shaft 11 protrudes outside the motor housing 5. The stator 3 is disposed on the outer peripheral side of the driving magnet 12. The stator 3 includes a stator core 13 and a driving coil 15 wound around a salient pole of the stator core 13 via an insulator 14. The end of the driving coil 15 is wound around and fixed to a terminal pin fixed to the insulator 14, and a substrate 16 is soldered and fixed to the terminal pin. One end of the power supply line 7 is soldered and fixed to the substrate 16.

In the following description, the axial direction of the rotary shaft 11 (i.e., the axial direction of the rotor 2, the X direction in fig. 1, etc.) is referred to as the "front-rear direction", and the Z direction in fig. 1, etc. orthogonal to the front-rear direction is referred to as the "up-down direction". Further, an output side (X1 direction side in fig. 1 and the like) of the rotary shaft 11 in the front-rear direction (axial direction of the rotary shaft 11) is referred to as a "front" side, an opposite side (X2 direction side in fig. 1 and the like) to the output of the rotary shaft 11 in the front-rear direction is referred to as a "rear (back)" side, one side in the up-down direction, that is, a Z1 direction side in fig. 1 and the like is referred to as an "upper" side, and the other side in the up-down direction, that is, a Z2 direction side in fig. 1 and the like is referred to as a "lower" side.

The detection mechanism 6 is a magnetic rotary encoder. The detection mechanism 6 includes a detection magnet 20 and a flat plate-shaped substrate 21 disposed on the back side of the detection magnet 20. The substrate 21 is disposed such that the thickness direction of the substrate 21 coincides with the front-rear direction. A magnetoresistive element and a hall element are mounted on the front surface of the substrate 21. The detection magnet 20 is fixed to a magnet holder 22. The magnet holder 22 is fixed to the rear end portion of the rotary shaft 11. The substrate 21 is fixed to the substrate holder 23. The board holder 23 is fixed to a bearing holder 27, which will be described later, constituting the motor case 5.

The motor case 5 includes: a cylindrical case main body 2 that opens in the front-rear direction; a bearing holder 26 fixed to the front end of the housing body 25; a bearing holder 27 fixed to the rear end of the housing main body 25; a cover 28 covering a connection portion of the power supply line 7 and the substrate 16; and a cover 29 covering the detection mechanism 6. A bearing 30 for rotatably supporting the rotary shaft 11 is attached to the bearing holder 26. A bearing 31 for rotatably supporting the rotary shaft 11 is attached to the bearing holder 27.

The cover 28 is fixed to the upper surface of the housing main body 25. A rubber bush 32 for preventing liquid such as water from penetrating into the motor case 5 is attached between the cover 28 and the case main body 25. The bush 32 is formed with an insertion hole 32a through which the power supply line 7 is inserted. The power supply line 7 is drawn out from the insertion hole 32a to the outside of the motor case 5.

The cover 29 is fixed to the rear surface of the bearing holder 27. As described above, the cover 29 covers the detection mechanism 6, and the detection mechanism 6 is accommodated in the motor case 5. As described above, the shielded wire 8 is connected to the detection mechanism 6. Specifically, one end of the shield wire 8 is connected to the substrate 21 via the connector 33. The shielded wire 8 is led out from the detection mechanism 6 toward the outside of the motor case 5. Specifically, the shielded wire 8 is drawn out toward the outside of the cover 29. The structure of the shield wire 8 and the structure of the lead portion of the shield wire 8 will be described below.

(Structure of shielded wire and Structure of lead-out portion of shielded wire)

Fig. 3 is a diagram for explaining the structure of the shield wire 8 and the bush 43 shown in fig. 2. Fig. 4 is a perspective view of the shield wire 8 and the cover 29 shown in fig. 1. Fig. 5 is an exploded perspective view of the cover 29, the bush 43, and the bush cover 44 shown in fig. 4. Fig. 6 is an exploded perspective view showing the cover 29, the bush 43, and the bush cover 44 shown in fig. 5 from a different direction.

The shielded wire 8 includes a center core 36, a shield material 37 covering the center core 36, and an insulating film 38 (see fig. 3) covering the shield material 37. The shield wire 8 of the present embodiment includes a plurality of core wires 36, and a shield material 37 covers the plurality of core wires 36. The intermediate core 36 is composed of a core wire (conductor wire) composed of a copper wire or the like and an insulating coating covering the core wire. The shield material 37 is made of a copper wire or the like woven into a mesh shape. The shield line 8 has formed therein: a core wire exposure portion 8a in which the shielding material 37 and the insulating film 38 are removed to expose the core wire 36; and a core wire coating portion 8b in which the core wire 36 is coated with a shielding material 37 and an insulating coating 38. Specifically, both ends of the shield wire 8 are core wire exposed portions 8a, and the portion of the shield wire 8 from which the core wire exposed portions 8a are removed is a core wire covering portion 8 b.

A shield material folded portion 8c is formed at a boundary portion between the central-core-wire exposed portion 8a and the central-core-wire covering portion 8b on one end side of the shield wire 8 (specifically, on the side of the shield wire 8 connected to the substrate 21), and the shield material 37 is folded back onto the outer peripheral surface of the insulating film 38 on the side of the central-core-wire covering portion 8b (see fig. 3). In the shield material folded-back portion 8c, the shield material 37, from which the insulating film 38 is removed and which is exposed to the outside, is folded back once toward the center wire covering portion 8b side, and the tip of the shield material 37 folded back on the outer peripheral surface of the insulating film 38 is directed toward the center wire covering portion 8b side. In the shielding material folded-back portion 8c, the shielding material 37 folded back on the outer peripheral surface of the insulating film 38 is twisted in the circumferential direction of the core wire covering portion 8 b. The outer diameter of the shielding material folded-back portion 8c is larger than the outer diameter of the core wire covering portion 8 b.

As described above, the shielded wires 8 are drawn out toward the outside of the cover 29. The cover 29 is formed of resin. The cover 29 is formed in a substantially square tubular shape with a bottom at the rear end. The cover 29 includes an upper wall portion 29a constituting an upper surface of the cover 29. A rubber bush 43 for preventing liquid from penetrating into the motor case 5 is attached to the cover 29. That is, the motor 1 includes a rubber bushing 43 for preventing liquid from penetrating into the motor case 5, and the bushing 43 is attached to the motor case 5.

A bush holding portion 29b for holding the bush 43 is formed in the cover 29. The bush holding portion 29b is formed on the upper wall portion 29 a. That is, the bush 43 is attached to a side wall portion of the motor housing 5 (specifically, an upper side wall portion of the cover 29). The bush holding portion 29b is formed with a notch 29c in which the bush 43 is disposed. The notch 29c is cut in a U shape from the front end of the upper wall portion 29a toward the back side. Further, a support wall portion 29d that supports the bush 43 from below is formed in the bush holding portion 29 b. The support wall 29d is disposed below the notch 29 c.

The support wall 29d is formed with a U-shaped notch 29 e. The notch 29e is cut out from the front end of the upper wall portion 29a toward the back side. The outer shape of the notch 29e is smaller than that of the notch 29c, and as shown in fig. 6, the upper surface of the support wall 29d is a plane perpendicular to the vertical direction. As shown in fig. 5, the lower surface of the support wall 29d also becomes a plane perpendicular to the vertical direction.

The bush 43 is formed with an insertion hole 43a through which the shield wire 8 is inserted. The insertion hole 43a penetrates the bush 43 in the vertical direction. The insertion hole 43a includes a small-diameter inner peripheral surface portion 43b in which the center wire covering portion 8b is disposed, and a large-diameter inner peripheral surface portion 43c in which the shielding material folded portion 8c is disposed and which has an inner diameter larger than that of the small-diameter inner peripheral surface portion 43 b. The insertion hole 43a of the present embodiment is constituted by a small diameter inner peripheral surface portion 43b and a large diameter inner peripheral surface portion 43 c.

The small-diameter inner peripheral surface portion 43b is disposed above the large-diameter inner peripheral surface portion 43 c. That is, the small-diameter inner peripheral surface portion 43b of the bush 43 held by the bush holding portion 29b formed on the upper wall portion 29a is disposed on the outer side of the motor housing 5 (specifically, on the outer side of the cover 29), and the large-diameter inner peripheral surface portion 43c is disposed on the inner side of the motor housing 5 (specifically, on the inner side of the cover 29). A step surface 43d is formed at a boundary portion between the small diameter inner peripheral surface portion 43b and the large diameter inner peripheral surface portion 43 c. The step surface 43d is an annular flat surface perpendicular to the vertical direction. The step surface 43d is a flat surface facing downward.

A liner cover 44 is fixed to the upper surface of the upper wall portion 29 a. The bush 43 is held by the bush holding portion 29b in a state of being sandwiched between the support wall portion 29d and the bush cover 44. The front surface of the bush 43 and the front surface of the cover 29 are arranged at the same position in the front-rear direction. The bushing cover 44 is formed with an insertion hole 44a that penetrates the bushing cover 44 in the vertical direction.

The core wire exposed portion 8a constituting one end portion of the shield wire 8 (specifically, an end portion of the shield wire 8 on the side connected to the substrate 21) is disposed inside the cover 29. That is, the core wire exposure portion 8a is disposed inside the motor case 5. The shield wire 8 is drawn out of the cover 29 from the insertion hole 43a of the bush 43 and the insertion hole 44a of the bush cover 44. The shielding material folded portion 8c is disposed on the large-diameter inner peripheral surface portion 43c of the bush 43. In the present embodiment, the entire shielding material folded portion 8c is disposed on the large-diameter inner peripheral surface portion 43 c. A part of the core wire exposed portion 8a is disposed in the notch 29 e. A part of the center wire coating portion 8b is disposed on the small-diameter inner peripheral surface portion 43b of the bush 43. The center wire coating portion 8b is press-fitted into the small-diameter inner peripheral surface portion 43 b.

The shielding material folded back portion 8c is in contact with the step surface 43 d. The shield material folded portion 8c is adhesively fixed to the large-diameter inner peripheral surface portion 43 c. That is, the shielding material folded portion 8c is adhesively fixed to the large diameter inner peripheral surface portion 43c in a state of being in contact with the stepped surface 43 d. Specifically, the shielding material folded-back portion 8c is adhesively fixed to the large-diameter inner peripheral surface portion 43c in a state where the upper end of the shielding material folded-back portion 8c is in contact with the stepped surface 43 d. As shown in fig. 3, the shield material folded-back portion 8c is covered with an adhesive 39 that adhesively fixes the shield material folded-back portion 8c to the large-diameter inner peripheral surface portion 43 c. The adhesive 39 covers the entire shielding material folded portion 8 c. The adhesive 39 is filled in the large-diameter inner peripheral surface portion 43 c.

As described above, in the shield material folded-back portion 8c, since the tip of the shield material 37 folded back on the outer peripheral surface of the insulating film 38 is directed toward the center wire coating portion 8b side, the tip of the shield material 37 folded back on the outer peripheral surface of the insulating film 38 is directed upward. That is, the leading end of the shielding material 37 folded back on the outer peripheral surface of the insulating film 38 faces the outside of the motor case 5 (specifically, the outside of the cover 29).

(main effect of the present embodiment)

As described above, in the present embodiment, the shield material folded back portion 8c is formed at the boundary portion between the central-wire exposed portion 8a and the central-wire covered portion 8b of the shield wire 8. In the present embodiment, the shielding material folded portion 8c disposed on the large diameter inner peripheral surface portion 43c of the bush 43 is bonded and fixed to the large diameter inner peripheral surface portion 43c by the adhesive 39 in a state of being in contact with the stepped surface 43d of the bush 43. Therefore, in the present embodiment, the stepped surface 43d, the shield material folded portion 8c, and the adhesive 39 can prevent the shield wire 8 from being pulled out when a pulling force is applied to the shield wire 8.

In the present embodiment, the small-diameter inner peripheral surface portion 43b is disposed on the outer side of the motor case 5, and the large-diameter inner peripheral surface portion 43c is disposed on the inner side of the motor case 5, so that the portion of the shield material folded portion 8c bonded to the large-diameter inner peripheral surface portion 43c does not appear in the appearance of the motor 1. Therefore, in the present embodiment, even if the shield wire 8 can be prevented from being pulled out when a pulling force is applied to the shield wire 8, the appearance of the motor 1 can be improved. In addition, in the present embodiment, since the shield material 37 of the shield wire 8 can be used to prevent the shield wire 8 from being pulled out, the structure of the motor 1 can be simplified. In addition, in the present embodiment, since it is not necessary to form a wiring fixing portion on the bearing holder 27 as in the motor described in patent document 1, the structure of the bearing holder 27 can be simplified.

In the present embodiment, the shield material folded-back portion 8c is disposed on the large-diameter inner peripheral surface portion 43c of the bush 43 and is fixed by adhesion, so that the amount of projection of the shield material folded-back portion 8c having a large outer diameter into the motor case 5 can be suppressed. In particular, in the present embodiment, since the entire shielding material folded-back portion 8c is disposed on the large-diameter inner peripheral surface portion 43c, the shielding material folded-back portion 8c does not protrude into the motor case 5.

Therefore, in the present embodiment, the shield material folded-back portion 8c can be disposed inside the motor case 5 without providing a space for disposing the shield material folded-back portion 8 c. Therefore, in the present embodiment, the influence of the shield material folded portion 8c on the assembly of the motor 1 can be reduced in the motor case 5, and as a result, the assembly of the motor 1 can be easily performed. In addition, in the present embodiment, since the influence of the shielding material folded portion 8c on the constituent parts disposed inside the motor case 5 can be reduced, the degree of freedom in designing the motor 1 can be improved.

In the present embodiment, in the shielding material folded-back portion 8c, the shielding material 37 folded back on the outer peripheral surface of the insulating film 38 is twisted in the circumferential direction of the core wire covering portion 8 b. Therefore, in the present embodiment, the outer diameter of the shielding material folded portion 8c can be increased as compared with the case where the shielding material 37 folded back to the outer peripheral surface of the insulating film 38 is not twisted in the circumferential direction of the core wire wrapping portion 8 b. Therefore, in the present embodiment, the difference between the outer diameter of the shield material folded portion 8c and the outer diameter of the core wire covering portion 8b can be increased, and the contact area between the stepped surface 43d of the bush 43 and the shield material folded portion 8c can be increased. As a result, in the present embodiment, the shield wire 8 can be effectively prevented from being pulled out when a pulling force acts on the shield wire 8.

In the present embodiment, the shielding material folded portion 8c is covered with the adhesive 39. That is, in the present embodiment, the shield material 37 folded back to the outer peripheral surface of the insulating film 38 is covered with the adhesive 39. Therefore, in the present embodiment, the insulating property of the shield material 37 folded back to the outer peripheral surface of the insulating film 38 can be ensured by the adhesive 39.

In the present embodiment, in the shield material folded-back portion 8c, the tip of the shield material 37 folded back on the outer peripheral surface of the insulating film 38 faces the center wire covering portion 8b side, not the center wire exposed portion 8a side. Therefore, in the present embodiment, the contact of the leading end of the shield material 37 with the center wire 36 can be prevented. Therefore, in the present embodiment, it is easy to ensure the insulation of the shield material 37 and the core wire 36.

In the present embodiment, the shielding material folded portion 8c disposed on the large diameter inner peripheral surface portion 43c of the bush 43 is adhesively fixed to the large diameter inner peripheral surface portion 43 c. Therefore, in the present embodiment, the rotation of the shield wire 8 with respect to the bush 43 can be prevented.

(other embodiments)

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made within a scope not changing the gist of the present invention.

In the above embodiment, a part of the shielding material folded portion 8c may protrude from the large diameter inner peripheral surface portion 43c toward the inner side of the cover 29. Even in this case, the shield material folded-back portion 8c can be disposed inside the motor case 5 even if the disposition space of the shield material folded-back portion 8c is narrowed. Therefore, substantially the same effects as those of the above-described embodiment can be obtained.

In the above-described embodiment, the shielding material 37 exposed to the outside with the insulating film 38 removed is folded back once toward the center wire covering portion 8b side in the shielding material folded-back portion 8c, but the shielding material 37 exposed to the outside with the insulating film 38 removed may be folded back plural times in the shielding material folded-back portion 8 c. In this case, the tip of the shielding material 37 folded back on the outer peripheral surface of the insulating film 38 may face the center-wire exposed portion 8a side. In the shield material folded-back portion 8c, the shield material 37 folded back on the outer peripheral surface of the insulating film 38 may not be twisted in the circumferential direction of the core wire covering portion 8 b.

In the above embodiment, the center wire coating portion 8b may not be press-fitted into the small-diameter inner peripheral surface portion 43 b. In the above-described embodiment, the detection means 6 may be other than a rotary encoder. In the above-described embodiment, the motor 1 is an inner rotor type motor, but the motor to which the configuration of the present invention is applied may be an outer rotor type motor.

Claims

1. An electric motor, comprising:

a motor main body portion having a rotor and a stator;

a motor case that houses the motor main body portion;

a detection mechanism housed in the motor housing;

a shielded wire drawn out from the detection mechanism toward an outside of the motor case; and

a bush made of rubber for preventing liquid from penetrating into the inside of the motor case,

the shielded wire is provided with: a center wire; a shielding material covering the center wire; and an insulating film covering the shielding material,

the shield wire is formed with: a central-core-wire exposing portion where the shielding material and the insulating film are removed to expose the central core wire; and a core wire coating portion in which the core wire is coated with the shielding material and the insulating coating,

a shielding material folded-back portion is formed at a boundary portion between the central-wire exposed portion and the central-wire covering portion, the shielding material of the shielding material folded-back portion being folded back onto an outer peripheral surface of the insulating coating on the central-wire covering portion side,

the core wire exposure portion is disposed inside the motor case,

the bushing is mounted to the motor housing,

an insertion hole through which the shield wire is inserted is formed in the bushing,

the insertion hole has a small-diameter inner peripheral surface portion on which the center wire covering portion is disposed, and a large-diameter inner peripheral surface portion on which the shielding material folded portion is disposed and which has an inner diameter larger than that of the small-diameter inner peripheral surface portion,

the small-diameter inner peripheral surface portion is disposed on an outer side of the motor housing, and the large-diameter inner peripheral surface portion is disposed on an inner side of the motor housing,

a step surface with which the shield material folded portion is brought into contact is formed at a boundary portion between the large-diameter inner peripheral surface portion and the small-diameter inner peripheral surface portion,

the shielding material folded portion is adhesively fixed to the large-diameter inner peripheral surface portion.

2. The motor according to claim 1,

in the shield material folded-back portion, the shield material folded back on the outer peripheral surface of the insulating film is twisted in the circumferential direction of the center wire covering portion.

3. The motor according to claim 1 or 2,

the insertion hole is formed by the small-diameter inner peripheral surface portion and the large-diameter inner peripheral surface portion.

4. The motor according to any one of claims 1 to 3,

the center wire coating portion is press-fitted into the small-diameter inner peripheral surface portion.

5. The motor according to any one of claims 1 to 4,

the shielding material folded-back portion is covered with an adhesive that adhesively fixes the shielding material folded-back portion to the large-diameter inner peripheral surface portion.

6. The motor according to any one of claims 1 to 5,

in the shielding material folded-back portion, a leading end of the shielding material folded back on the outer peripheral surface of the insulating film faces an outside of the motor case.