JP2008125309A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assure insulation at the joint of the external connection terminal and the power input terminal of a stator while preventing a screw from loosening without causing cost increase. <P>SOLUTION: A power input terminal 55 connected with an external power supply is connected with the external connection terminal 54 of a brushless motor 1 by means of a terminal fixing screw 57. A heat-resistant rubber insulation cap 59 is fixed to one end of the power input terminal 55. The insulation cap 59 covers the one end of the power input terminal 55 and the joint of both terminals 54 and 55. Head portion 57a of the terminal fixing screw 57 is also covered with the cover body 66 of the insulation cap 59 and insulated from other components. A protrusion 67 formed on the cover body 66 abuts against the right end face 41a of the housing. The cover body 66 pushed by the protrusion 67 bites into the tool fitting hole 57b of the screw 57, thus locking the screw 57. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brushless motor used for an electric power steering apparatus and the like, and more particularly to an insulating structure in a connection portion between an external connection terminal and a power input terminal of a stator.

  In recent years, many vehicles have been equipped with so-called power steering devices for assisting steering force of automobiles and the like. As such power steering devices, in recent years, vehicles equipped with electric power steering devices (so-called electric power steering devices) are increasing from the viewpoint of reducing engine load and weight. In this electric power steering device (hereinafter abbreviated as EPS), the motor as a driving source thereof is required to be downsized and high in performance because the device is arranged in a narrow bonnet space. Conventionally, DC motors with brushes have been widely used as such motors, but recently, with the improvement of control technology, the adoption of brushless motors that are superior in terms of miniaturization and high performance has increased. is doing.

  FIG. 5 is an explanatory view showing a stator structure of such a brushless motor for EPS. As shown in FIG. 5, the stator 101 includes a stator core 102 formed by laminating many steel plates, and a coil 103 using a copper wire is wound around the stator core 102. A plurality of teeth and slots are alternately formed on the outer periphery of the stator core 102, and a coil 103 is wound around each tooth via an insulator 104 made of synthetic resin. A terminal unit 105 is attached to one end side of the stator core 102. The terminal unit 105 has a large number of coil feed terminals 106 protruding in the radial direction. Each coil feed terminal 106 has a terminal portion 103a of the coil 103 (a winding start portion or a winding end portion of the coil 103). It is connected.

  The terminal unit 105 is further provided with an external connection terminal 107 that is electrically connected to the coil power supply terminal 106. A power input terminal 108 connected to an external power source is connected to the external connection terminal 107. Electric power is appropriately supplied to each coil 103 from the power input terminal 108 via the terminal unit 105. Conventionally, soldering, spot welding (resistance welding), arc welding (plasma welding), screwing, and the like are used as a method for connecting the external connection terminal 107 and the power input terminal 108. In recent years, with the reduction in size and weight of motors and higher output, the internal layout of the motor has become very highly integrated, and due to work space and other reasons, the number of cases where screwing is used rather than various welding methods has increased. ing.

FIG. 6 is an explanatory diagram showing a configuration of a connection portion between the external connection terminal 107 and the power input terminal 108, and shows a configuration of a motor in which both terminals are connected by screwing. As shown in FIG. 6, in the motor, the external connection terminal 107 and the power input terminal 108 are fixed by a terminal fixing screw 109 (hereinafter abbreviated as a screw 109). A screw 109 is attached from the axial direction, and is screwed into a nut 111 disposed on the terminal unit 105. As a result, the external connection terminal 107 and the power input terminal 108 are fixed in contact with each other, and both are electrically connected. The power input terminal 108 extends to the outside of the motor housing 112 (upward in FIG. 6) and is connected to a power supply lead wire by a coupler (not shown).
JP 2004-48851 A

  On the other hand, as the inside of the motor is highly integrated, each component is housed in the motor in a state of being very close to each other. For this reason, in recent brushless motors, electrical insulation between components is indispensable in terms of product quality. For example, in the connection portion between the external connection terminal 107 and the power input terminal 108 as described above, the adjacent housing 113 and the screw 109 are close to each other as shown in FIG. Become. In this case, an insulation coating or the like can be considered as an insulation means. However, since the screws are attached during the assembly of the motor, the partial coating is difficult to work and the man-hour is increased, which contributes to the cost increase. It also becomes. For this reason, at present, consideration is given to the design so that a gap is provided between the screw 109 and the housing 113 as much as possible, and there is also a problem that hinders reduction in size and weight.

  Also, in the case of connection with screws, the problem of loosening of the screws cannot be avoided, and there is a possibility that problems such as poor conduction due to dropping off of the screws, or inability to secure insulation due to the screws or terminals coming into contact with other parts may occur. . For this reason, as a measure for preventing loosening of screws in the motor, generally, a method using adhesion or painting such as screw lock is adopted. However, since the adhesive and paint are organic, there is a problem that the reliability of the electrical connection portion may be deteriorated over time.

  An object of the present invention is to provide a brushless motor capable of ensuring both insulation and preventing screws from loosening at a connection portion between an external connection terminal of a stator and a power input terminal without causing an increase in cost.

  The brushless motor of the present invention is a brushless motor comprising a stator having a steel core, a coil wound around the core, and a rotor arranged to be rotatable with respect to the stator, An external connection terminal that is disposed inside the motor and is electrically connected to the coil, a power input terminal that is electrically connected to an external power source, and is connected to the external connection terminal and the motor, and an insulating material. And a cap member that covers a connection portion between the external connection terminal and the power input terminal.

  In the brushless motor of the present invention, by providing a cap member made of an insulating material that covers the connection portion between the external connection terminal and the power input terminal, between the external connection terminal and the power input terminal and other components. Contact prevention is achieved, and the insulation of the terminal connecting portion and its vicinity is improved.

  In the brushless motor, the cap member may be attached to one end of the power input terminal on the motor inner side. The cap member may have a terminal mounting portion to which the power input terminal is mounted and a cover portion that covers the connection portion between the external connection terminal and the power input terminal. Furthermore, the terminal mounting portion may be configured to have a hollow housing portion and a plurality of terminal insertion portions formed in the housing portion and separated by a partition wall. In addition, the external connection terminal and the power input terminal may be coupled by a screw member, and the head portion of the screw member may be covered by the cover portion. Insulated from the member.

  On the other hand, it is good also as a structure which has the cover main body in which the said connection part is accommodated in the said cover part, and the projection part protrudingly provided on the said cover main body. In this case, the external connection terminal and the power input terminal may be coupled by a screw member, and the cover main body may be pressed against the screw member by a member that is in contact with the protruding portion. The screw member is prevented from rotating by the cover body. Further, the screw member is attached along the axial direction, and the cover main body is pushed into a tool fitting hole formed in the screw member head by a member that abuts on the protrusion from the axial direction. In this case, the screw member is more firmly prevented from rotating.

  According to the brushless motor of the present invention, the external connection terminal electrically connected to the stator coil, the external connection terminal electrically connected to the external power source, and the power input terminal connected inside the motor are provided. Since the cap member made of an insulating material that covers the connection portion between the external connection terminal and the power input terminal is provided, it is possible to prevent contact between the external connection terminal or the power input terminal and other components. Thereby, the insulation of a terminal connection part improves and it becomes possible to aim at the reliability improvement of a motor.

  In addition, since the head of the screw member that couples the external connection terminal and the power input terminal is covered with the cover portion of the cap member, it is possible to prevent contact between the screw member head and other components. Become. Thereby, the insulation of a terminal connection part, especially a screw member improves, and it becomes possible to aim at the reliability improvement of a motor.

  Furthermore, the cover portion of the cap member has a cover main body in which the connection portion is accommodated and a protrusion protruding from the cover main body, and the cover main body is screwed by the member in contact with the protrusion. The screw member can be prevented from rotating by the cover body. Thereby, it becomes possible to satisfy | fill two functions, an insulation and the loosening prevention of a screw, with one member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a brushless motor to which the present invention is applied. A motor 1 shown in FIG. 1 is used as a power source for a rack-assisted EPS, and has a configuration in which a rack shaft 2 penetrates the motor 1. The rotation of the motor 1 is transmitted to the rack shaft 2 via the ball screw mechanism 3 and becomes a steering assist force.

  The motor 1 has an inner rotor type device configuration in which a stator 11 is disposed outside and a rotor 21 is disposed inside. The stator 11 includes a housing 12, a stator core 13 fixed to the inner peripheral side of the housing 12, and a coil 14 wound around the stator core 13. The housing 12 is formed of iron or the like, and a housing 41 made of aluminum die casting is attached to the left end side in the drawing. The stator core 13 has a structure in which a large number of steel plates are laminated, and a plurality of (in this case, nine) teeth project from the inner peripheral side of the stator core 13. A coil 14 is wound around a slot (nine slots) formed between the teeth via an insulator made of synthetic resin, and insulation of the coil 14 wound between the slots is secured by the insulator.

  Similarly to the conventional brushless motor shown in FIG. 5, a stator insulator 51 (hereinafter abbreviated as an insulator 51) is attached to both ends of the stator core 13. A terminal unit 52 is attached to the left end of the left side (insulator 51a) in FIG. A large number of coil power supply terminals 53 protrude from the terminal unit 52 in the radial direction. Each coil power supply terminal 53 is connected to a terminal portion of the coil 14 (a winding start portion or a winding end portion of the coil 14).

  The terminal unit 52 is further provided with an external connection terminal 54 electrically connected to the coil power supply terminal 53. One end of a power input terminal 55 is connected to the external connection terminal 54, and the other end of the power input terminal 55 is disposed in a female coupler 56. A lead wire (not shown) for power feeding is connected to the coupler 56 by a male coupler. Electric power is appropriately supplied to each coil 14 from the coupler 56 via the power input terminal 55 and the terminal unit 52.

  FIG. 2 is an explanatory diagram illustrating a configuration of a connection portion between the power input terminal 55 and the external connection terminal 54. As shown in FIG. 2, the power input terminal 55 and the external connection terminal 54 are fixed by terminal fixing screws (screw members) 57 similarly to the motor of FIG. 6. A terminal fixing screw 57 (hereinafter abbreviated as screw 57) is attached along the axial direction (left side in FIGS. 1 and 2) and screwed into a nut 58 disposed in the terminal unit 52. Thereby, the power input terminal 55 is fixed in contact with the external connection terminal 54, and both are electrically connected. On the other hand, in the motor 1 according to the present invention, as shown in FIG. 2, an insulating cap (cap member) 59 formed of heat-resistant rubber (insulating material) is attached to one end side of the power input terminal 55. . FIG. 3 is a perspective view of the insulating cap 59 as viewed from the front upper side, and FIG. 4 is a perspective view of the insulating cap 59 as viewed from the lower back side.

  As shown in FIGS. 3 and 4, the insulating cap 59 is provided with a terminal mounting portion 60 and a screw cover portion 61. The terminal mounting part 60 and the screw cover part 61 are integrated by a connection piece 62. The terminal mounting portion 60 includes a hollow housing portion 63 formed in a flat rectangular parallelepiped shape, and a plurality of terminal insertion portions 65 formed in the housing portion 63 and separated by a partition wall 64. The terminal insertion portion 65 is formed through the inside of the housing portion 63 along the short side direction. Three terminal insertion portions 65 are formed in accordance with the U, V, and W phase power input terminals 55, and are separated by a partition wall 64. The power input terminals 55 are inserted into the respective terminal insertion portions 65 while being insulated from each other. Thereby, the one end side of the power input terminal 55 is covered with an insulating material, and contact between terminals or between the terminal and peripheral parts can be prevented, and electrical insulation of the power input terminal 55 is ensured.

  The screw cover portion 61 includes a cover body 66 having a substantially U-shaped cross section, and a protrusion 67 protruding from the cover body 66. When the insulating cap 59 is attached to the power input terminal 55, as shown in FIG. 2, the connection portion between the power input terminal 55 and the external connection terminal 54 is covered by the cover body 66, and a screw is placed in the inner space 66 a of the cover body 66. The head 57a is accommodated. That is, the vicinity of the connecting portion of both terminals 54 and 55 and the screw head 57 a are covered with the cover body 66. For this reason, the connection part of both the terminals 54 and 55 is covered with an insulating material, and a contact with a connection part, especially the screw 57, and peripheral components can be prevented, and the electrical insulation of a connection part is ensured. The

  Further, when the insulating cap 59 is attached to the power input terminal 55, the protrusion 67 is formed so as to be disposed at the approximate center of the screw head 57a. On the other hand, when the housing 41 is assembled to the motor 1, the right end face 41 a of the housing 41 in FIGS. For this reason, when the housing 41 is assembled, the protrusion 67 is pushed in the axial direction by the right end surface 41a of the housing, and the cover main body 66 is pushed against the screw head 57a. At that time, as shown in FIG. 2, the surface of the cover body 66 opposite to the protrusion 67 is pushed by the housing right end surface 41 a and is pushed into the tool fitting hole 57 b of the screw 57 and bites into the hole. As a result, the screw 57 is prevented from rotating by the rubber insulating cap 59 and the screw 57 is prevented from loosening.

  As described above, in the motor 1 of the present invention, the insulation near the terminal connection portion is improved by attaching the insulating cap 59 as shown in FIGS. In addition, the screw 57 can be prevented from loosening. That is, the insulating cap 59 covers one end portion of the power input terminal 55 and the connection portion of both terminals 54 and 55 with an insulating material, and prevents contact between the terminals or between the terminal and other components. The insulation in the vicinity of the portion is improved, and the reliability of the brushless motor can be improved. In addition, the screw 57 can be prevented from loosening by press-contacting a part of the insulating cap 59 to the screw head 57a, and the reliability of the brushless motor can be improved. Therefore, the motor 1 can achieve two functions of electrical insulation and screw loosening with a single component without causing an increase in cost due to an inexpensive component such as a rubber molded product. Further, the rubber insulating cap 59 has less variation during mass production and higher reliability over time than the loosening prevention by painting or adhesion, so that the reliability of the brushless motor can also be improved in this respect.

  The rotor 21 is disposed inside the stator 11 and has a configuration in which a cylindrical rotor shaft 22, a rotor core 23, a magnet 24, and a magnet cover 25 are arranged coaxially. The rack shaft 2 is inserted inside the rotor shaft 22. A cylindrical rotor core 23 is externally provided on the outer periphery of the rotor shaft 22. A magnet 24 having a 6-pole configuration is fixed to the outer periphery of the rotor core 23.

  The magnet 24 is a rare earth magnet such as a neodymium iron magnet that is small and has a high magnetic flux density. Thus, by using a rare earth magnet for the magnet 24, the motor can be miniaturized, the inertia of the rotor 21 is reduced, and the steering feeling is improved. The magnet 24 has a ring shape, and a plurality of magnetic poles are alternately arranged N and S in the circumferential direction. A plurality of segment magnets may be used as the magnet 24. A magnet cover 25 is externally provided on the outside of the magnet 24 so that even if the magnet is broken, the motor 1 is not locked by the broken piece.

  An aluminum die cast housing 31 is attached to the right end side of the housing 12 in the figure. The housing 31 accommodates a bearing 32 that supports the right end side of the rotor 21 and a resolver 33 that detects the rotation of the rotor 21. The resolver 33 includes a resolver stator 34 fixed to the housing 31 side and a resolver rotor 35 fixed to the rotor 21 side. A coil 36 is wound around the resolver stator 34, and an excitation coil and a detection coil are provided.

  A resolver rotor 35 fixed to the rotor shaft 22 is disposed inside the resolver stator 34. The resolver rotor 35 has a configuration in which metal plates are laminated, and has convex portions in three directions. When the rotor shaft 22 rotates, the resolver rotor 35 also rotates in the resolver stator 34. A high frequency signal is given to the exciting coil of the resolver stator 34, and the phase of the signal output from the detection coil changes due to the proximity of the convex portion. The rotational position of the rotor 21 is detected by comparing the detection signal with the reference signal. Then, based on the rotational position of the rotor 21, the current to the coil 14 is appropriately switched, and the rotor 21 is rotationally driven.

  A housing 41 is attached to the left end side of the housing 12, and the ball screw mechanism 3 is incorporated in the housing 41. The ball screw mechanism 3 includes a nut portion 42, a screw portion 43 formed on the outer periphery of the rack shaft 2, and a large number of balls 44 interposed between the nut portion 42 and the screw portion 43. . The rack shaft 2 is supported so as to be reciprocable in the left-right direction by the nut portion 42 in a state where the rotation around the shaft is restricted, and moves in the left-right direction as the nut portion 42 rotates.

  The nut portion 42 is fixed to the left end portion of the rotor shaft 22 and is rotatably held by an angular bearing 45 fixed to the housing 41. The angular bearing 45 is fixed in a state where axial movement is restricted between bearing fixing rings 46 a and 46 b screwed into the opening of the housing 41 and a stepped portion 47 formed inside the housing 41. ing. The axial movement between the nut portion 42 and the angular bearing 45 is restricted by a bearing fixing ring 48 screwed into the left end of the nut portion 42 and a step portion 49 formed on the outer periphery of the nut portion 42. Is done.

  In an EPS equipped with such a motor 1, the steering handle is first operated to rotate the steering shaft, and the rack shaft 2 is moved in a direction corresponding to this rotation to perform a steering operation. When a steering torque sensor (not shown) is activated by this operation, electric power is supplied from the battery to the coil 14 via the lead wire according to the detected torque. When electric power is supplied to the coil 14, the motor 1 operates and the rotor shaft 22 rotates. When the rotor shaft 22 rotates, the nut portion 42 coupled therewith rotates, and the steering assist force in the axial direction is transmitted to the rack shaft 2 by the action of the ball screw mechanism 3. Thereby, the movement of the rack shaft 2 is promoted, and the steering force is assisted.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, the power input terminal 55 exists individually for each phase, and the motor 1 is structured such that each terminal can be in contact with the structure. Although provided, the partition wall 64 is not necessary when a configuration in which each terminal does not come into contact with each other by a direct coupler or the like is employed. If the partition wall 64 can be omitted, the die can be simplified correspondingly, and the die cost can be reduced.

  In the above-described embodiment, the example in which the stator according to the present invention is used for a brushless motor used as an EPS drive source has been described. However, the stator is not limited to a brushless motor for EPS, and brushless for other uses. Widely applicable to motors. Further, the present invention can be widely applied to general brushless motors as well as motors for EPS and various in-vehicle electric products. Furthermore, in the above-described embodiment, the brushless motor used for the rack assist type EPS is shown, but the present invention can also be applied to other types of EPS motors such as a column assist type.

It is sectional drawing which shows the structure of the brushless motor to which this invention is applied. It is explanatory drawing which shows the structure of the connection part of a power input terminal and an external connection terminal. It is the perspective view which looked at the insulating cap from the front upper direction. It is the perspective view which looked at the insulating cap from the back lower surface. It is explanatory drawing which shows the stator structure of the brushless motor for EPS. It is explanatory drawing which shows the structure of the connection part of an external connection terminal and a power input terminal, and has shown the structure of the motor which connected both terminals by screwing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Rack shaft 3 Ball screw mechanism 11 Stator 12 Housing 13 Stator core 14 Coil 21 Rotor 22 Rotor shaft 23 Rotor core 24 Magnet 25 Magnet cover 31 Housing 32 Bearing 33 Resolver 34 Resolver stator 35 Resolver rotor 36 Coil 41 Housing 41a Right end surface 42 Nut Part 43 Screw part 44 Ball 45 Angular bearings 46a, 46b Bearing fixing ring 47 Step part 48 Bearing fixing ring 49 Step part 51 Stator insulator 51a Insulator 52 Terminal unit 53 Coil feed terminal 54 External connection terminal 55 Power input terminal 56 Coupler 57 Terminal fixing screw (screw member)
57a Head 57b Tool fitting hole 58 Nut 59 Insulation cap (cap member)
60 Terminal mounting part 61 Screw cover part 62 Connection piece 63 Housing part 64 Partition 65 Terminal insertion part 66 Cover body 66a Inner space 67 Projection part
101 stator
102 stator core
103 coil
103a terminal
104 Insulator
105 Terminal unit
106 Coil feed terminal
107 External connection terminal
108 Power input terminal
109 Terminal fixing screw
111 Nut
112 Motor housing
113 housing

Claims (8)

A stator comprising a steel core and a coil wound around the core;
A brushless motor having a rotor rotatably arranged with respect to the stator,
An external connection terminal disposed inside the motor and electrically connected to the coil;
A power input terminal electrically connected to an external power source and connected to the external connection terminal and the motor;
A brushless motor comprising a cap member formed of an insulating material and covering a connection portion between the external connection terminal and the power input terminal.   2. The brushless motor according to claim 1, wherein the cap member is attached to one end of the power input terminal on the motor inner side.   3. The brushless motor according to claim 1, wherein the cap member includes a terminal mounting portion to which the power input terminal is mounted, and a cover portion that covers the connection portion between the external connection terminal and the power input terminal. A brushless motor characterized by that.   4. The brushless motor according to claim 3, wherein the terminal mounting portion includes a hollow housing portion and a plurality of terminal insertion portions formed in the housing portion and separated by a partition wall. .   5. The brushless motor according to claim 3, wherein the external connection terminal and the power input terminal are coupled by a screw member, and a head portion of the screw member is covered by the cover portion.   5. The brushless motor according to claim 1, wherein the cover portion includes a cover main body in which the connection portion is accommodated, and a protrusion protruding on the cover main body. Brushless motor characterized by   7. The brushless motor according to claim 6, wherein the external connection terminal and the power input terminal are coupled by a screw member, and the cover body is pressed against the screw member by a member in contact with the protruding portion. Brushless motor.   8. The brushless motor according to claim 7, wherein the screw member is attached along an axial direction, and the cover body is a tool fitting formed on the screw member head by a member that abuts on the protrusion from the axial direction. A brushless motor that is pushed into a hole.

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