JP2005312087A - Electric power steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering system capable of shortening an overall length without impairing the performance or assembling workability. <P>SOLUTION: A stator 30 is composed by integrally resin-molding a laminated core 16 wound with a coil 15, a Hall IC 17 for detecting the magnetic force of a permanent magnet 13 for sensing, a board 18 mounting the Hall IC 17, a terminal (bus bar) 19 for connecting the coil 15, and a wire connection terminal (connector) 31 for the terminal connecting with the coil 15 and the terminal for outputting a signal of the Hall IC 17. Since a brushless motor can be fixed to a worm gear mechanism by a flange 33 provided in the stator 30, a conventional metallic cover can be eliminated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering apparatus capable of reducing the overall length without impairing performance or assemblability.
[0002]
[Prior art]
As an electric power steering device for a vehicle, the rotation output of an electric motor serving as an auxiliary steering torque is decelerated by a gear device and transmitted to the output shaft of the steering mechanism, and the steering force applied to the steering wheel is assisted to steer the wheel. What is comprised so that it may perform is known. In such an electric power steering apparatus, power is transmitted to the output shaft while reducing the rotation of the electric motor using a power transmission mechanism provided in the housing.
[0003]
As the electric motor used in the electric power steering apparatus, a motor with a brush has been mainly used. However, in recent years, a brushless motor is being shifted in order to improve reliability and further improve efficiency.
[0004]
An electric power steering apparatus provided with this brushless motor is shown in FIG. An output shaft 1 is connected to an input shaft (not shown) connected to a steering wheel (not shown) via a torsion bar (not shown) or the like, and the worm wheel 2 of the worm gear reduction mechanism is fixed to the output shaft 1. It is.
[0005]
The worm wheel 2 meshes with a worm 5 rotatably supported by a gear housing 3 by a bearing 4 or the like.
[0006]
A motor cover 7 of a brushless motor is connected to the gear housing 3 via a flange (partition plate) 6. A rotor 10 of a brushless motor is rotatably supported on the flange (partition plate) 6 and the motor cover 7 via bearings 8 and 9, respectively. The rotor 10 and the worm 5 are connected by a spline fitting portion 11, and both are movable in the axial direction and are not relatively rotatable.
[0007]
On the outer diameter side of the rotor 10, a cylindrical rotational driving permanent magnet 12 is attached to a laminated iron core 15 described later, and a ring-shaped sensing permanent magnet 13 is attached.
[0008]
A cylindrical stator 14 is provided on the inner diameter side of the motor cover 7. The stator 14 includes a laminated iron core 16 around which the coil 15 is wound, a Hall IC 17 that detects the magnetic force of the sensing permanent magnet 13, a substrate 18 on which the Hall IC 17 is mounted, and a terminal (bus bar) 19 that connects the coil 15. Are integrally formed by resin molding.
[0009]
In addition, a terminal (bus bar) 19 is connected with a wire cord 20 for a terminal connected to the coil 15 and a terminal for outputting a signal of the hold IC 17 by soldering or the like.
[0010]
Patent Document 1 discloses a brushless motor sharing a rotor bearing and a worm bearing in order to shorten the overall length of the motor.
[0011]
[Patent Document 1]
International Publication No. 99/65758 Pamphlet [0012]
[Problems to be solved by the invention]
In recent years, the required output of electric power steering devices has increased along with the increase in the number of vehicles to be mounted. On the other hand, motors are required to increase their output, but from the viewpoint of space saving, they are small in size. There is also a demand for it.
[0013]
Further, if the Hall IC 17 is too close to the coil 15, there is a risk of malfunction due to the magnetic force generated from the coil 15. Therefore, it is necessary to dispose the Hall IC 17 apart from the coil 15 by a predetermined interval (predetermined space). It may be difficult to shorten the overall length.
[0014]
Furthermore, it is necessary to attach brackets and flanges that support the bearings 8 and 9 to the outer periphery or end face of the stator 14, and it is difficult to reduce the axial length of the rotor 10 including the bearings 8 and 9. Sometimes.
[0015]
Patent Document 1 discloses a brushless motor sharing a rotor bearing and a worm bearing in order to shorten the overall length of the motor.
[0016]
However, in this case, there is a problem that the radial position of the rotor is displaced due to a load change of the worm, and accordingly, vibration is generated or characteristics are changed. In addition, when assembling, it is necessary to strictly manage in order to prevent iron scraps from adhering to the rotor equipped with the permanent magnet for rotational drive, and the rotor and stator must be assembled separately, and assembly workability is improved. There is a problem that assembly man-hours increase because of damage. In addition, the motor cannot be inspected unless the worm gear mechanism and the brushless motor are assembled, and the performance of the motor alone cannot be inspected.
[0017]
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an electric power steering device capable of shortening the overall length without impairing performance and assembly workability.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, an electric power steering apparatus according to claim 1 of the present invention generates an auxiliary steering torque from a brushless motor in response to a steering torque applied to a steering wheel, and decelerates by a reduction gear. In the electric power steering device that transmits to the output shaft of the steering mechanism
The rotor is provided with a cylindrical rotational driving permanent magnet and a detection object for detecting the rotation angle of the rotor,
A cylindrical stator facing the rotor has a resin core integrally formed with a laminated core around which a coil is wound, a detecting means for detecting a rotation angle of the rotor from the detected body, and a terminal for connecting the coil. Molded
Two bearings that rotatably support the rotor are supported by the stator.
[0019]
Thus, according to the first aspect, since the two bearings that rotatably support the rotor are supported by the stator, the radial gap between the laminated core of the stator and the rotor is strictly limited. Therefore, it is possible to maintain a stable performance with low noise by reducing transmission of vibration and the like.
[0020]
Moreover, since the stator covers the coil, the laminated iron core, the detection means, and the terminal and is integrally resin-molded, it can also serve as a conventional metal motor cover. Therefore, the stator allows the brushless motor to be mounted on the speed reducer, eliminates the need for a conventional metal motor cover, reduces the number of parts and assembly steps, and reduces manufacturing costs. be able to.
[0021]
According to a second aspect of the present invention, in the electric power steering apparatus according to the second aspect, the stator includes a blocking wall that closes the opening on the anti-reduction gear side and holds one of the two bearings. .
[0022]
As described above, according to the second aspect, the stator closes the opening on the anti-reduction gear side and has a blocking wall for holding one of the two bearings. Therefore, this one bearing can be easily attached to the blocking wall.
[0023]
Furthermore, in the electric power steering apparatus according to claim 3, the other of the two bearings is on the inner diameter side of the stator, and between the rotation driving permanent magnet and the detected body, It is arranged.
[0024]
Thus, according to the third aspect, the other of the two bearings is disposed on the inner diameter side of the stator and between the permanent magnet for rotation driving and the detected body. In other words, the bearing is arranged in a space for preventing malfunction between the detection means and the coil, so that the overall length of the rotor can be shortened, and thus the overall length of the brushless motor can be shortened. Can do.
[0025]
Further, the bearing is arranged in a space for preventing malfunction between the detection means and the coil, and when the bearing is a magnetic body, the bearing forms a magnetic path for confining the magnetic flux from the coil. Therefore, the influence of the magnetic flux generated from the coil on the detection means is reduced, and the sensitivity of the detection means can be improved.
[0026]
Furthermore, the electric power steering apparatus according to claim 4 is characterized in that the stator has an inner diameter that changes stepwise in the axial direction.
[0027]
Thus, according to the fourth aspect, the inner diameter of the stator changes stepwise in the axial direction. That is, the inner diameter of the stator has a large diameter on the opening side, and gradually changes from a large diameter to a small diameter as it advances toward the back side. Therefore, after the resin molding and curing, the cored bar of the mold can be pulled out without being caught, and the mold can be smoothly cut out.
[0028]
The stator has an inner diameter that changes stepwise in the axial direction. That is, the inner diameter of the stator has a large diameter on the opening side, and gradually changes from a large diameter to a small diameter as it advances toward the back side. Therefore, the rotor to which the bearing is attached can be inserted from the opening side having the maximum diameter, and the assembly workability can be improved.
[0029]
Therefore, since the brushless motor can be assembled to the speed reducer after assembling, the assembly workability is not impaired, and the performance and the like can be inspected with the brushless motor alone. .
[0030]
Furthermore, the electric power steering apparatus according to claim 5 is characterized in that the stator has an electric wire connecting terminal integrally.
[0031]
Thus, according to the fifth aspect, the stator integrally has the wire connection terminal. That is, since the stator is integrally formed with the terminal connected to the coil and the wire connecting terminal (connector) for outputting the signal of the detecting means, the conventional wire cord is soldered or the like. The work that has been connected can be made unnecessary, and the number of parts and the number of assembly steps can be reduced.
[0032]
Furthermore, in the electric power steering apparatus according to claim 6, the stator has a flange on the outer surface thereof for mounting the brushless motor on the speed reducer, and the flange is disposed near the center of the stator shaft length direction. It is characterized by being.
[0033]
Thus, according to the sixth aspect, the stator has the flange for mounting on the reduction gear on the outer surface thereof. For this reason, the brushless motor can be mounted on the reduction gear by the flange of the stator, the conventional metal motor cover and its mounting flange can be dispensed with, and the number of parts and assembly man-hours can be reduced. Manufacturing cost can be reduced. Furthermore, since this flange is provided near the center of the stator shaft length direction, the distance between the center of gravity of the motor and the flange can be shortened, and the force generated on the flange due to vibration or the like is reduced, so the required strength of the flange is lowered. That is, the weight and size can be reduced.
[0034]
Furthermore, the electric power steering apparatus according to a seventh aspect is characterized in that the detected object is installed at a rotor end opposite to the motor output side end.
[0035]
Thus, according to claim 7, by providing the detected object at the rotor end opposite to the motor output side end, the interference portion between the gear housing and the wire connection terminal is eliminated, and the shape is simplified. It is possible to improve dustproof and waterproof properties, and it is possible to prevent intrusion of iron scrap or the like into the interior of the motor assembly alone.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an electric power steering apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0037]
FIG. 1 is a longitudinal sectional view of an electric power steering apparatus according to an embodiment of the present invention.
[0038]
As shown in FIG. 1, an output shaft 1 is connected to an input shaft (not shown) connected to a steering wheel (not shown) via a torsion bar (not shown) and the like, and a worm gear speed reduction is connected to the output shaft 1. The worm wheel 2 of the mechanism (reduction gear) is fixed.
[0039]
The worm wheel 2 meshes with a worm 5 rotatably supported by a gear housing 3 by a bearing 4 or the like.
[0040]
The rotor 10 of the brushless motor and the worm 5 are connected by a spline fitting portion 11, and both are movable in the axial direction and are not relatively rotatable.
[0041]
On the outer diameter side of the rotor 10, a cylindrical rotational driving permanent magnet 12 is attached to a laminated iron core 15 described later, and a ring-shaped sensing permanent magnet 13 (detected body) is attached. .
[0042]
A cylindrical stator 30 is provided on the inner diameter side of the motor cover 7. The stator 30 includes a laminated iron core 16 around which the coil 15 is wound, a Hall IC 17 (detection means) that detects the rotation angle of the rotor 10 by detecting a magnetic field of the sensing permanent magnet 13 (detected body), Wire connection terminal (connector) for the board 18 on which the Hall IC 17 is mounted, the terminal (bus bar) 19 for connecting the coil 15, the terminal connected to the coil 15 and the terminal for outputting the signal of the Hall IC 17 (detection means) ) 31 is integrally formed by resin molding. Further, the stator 30 integrally has a flange 33 on its outer surface for mounting the brushless motor to the worm gear mechanism (reduction gear). Further, the detecting means and the detection target for detecting the angle of the rotor 10 may be not only a Hall IC / permanent magnet but also a resolver, an induct coder, or the like.
[0043]
The wire connection terminal (connector) 31 may be made of the same material as the resin to be molded, or may be made of a different material. The wire connection terminal (connector) 31 is molded by PBT or PA6 generally used for a connector, and then the stator. 30 may be integrally formed.
[0044]
Since the stator 30 covers the coil 15, the laminated iron core 16, the Hall IC 17 (detection means), the substrate 18 and the terminal (bus bar) 19 and is integrally resin-molded, the conventional metal motor cover (7 ) Can also be used.
[0045]
Accordingly, the brushless motor can be mounted on the worm gear mechanism by the flange 33 of the stator 30, so that the conventional metal motor cover (7) and its mounting flange can be dispensed with, and the number of parts and the number of assembly steps can be reduced. Thus, the manufacturing cost can be reduced.
[0046]
In the present embodiment, the bearing 8 is an inner diameter side of the stator 30 and rotatably supports the worm side of the rotor 10 between the rotational driving permanent magnet 12 and the sensing permanent magnet 13 (detected body). Is arranged.
[0047]
Specifically, the bearing 8 is attached to the inner diameter side of the stator 30 molded by resin molding via the cylindrical bracket 34. However, the bearing 8 may be directly attached to the inner diameter side of the stator 30 without providing the bracket 34.
[0048]
The stator 30 has a blocking wall 35 that closes the opening on the anti-worm side and holds the bearing 9 that rotatably supports the rotor 10. Specifically, the bearing 9 is housed and held in the recess 36 of the closing wall 35.
[0049]
Thus, since the two bearings 8 and 9 that support the rotor 10 rotatably are supported by the stator 30, the radial gap between the laminated core 16 of the stator 30 and the rotor 10 is as follows. It can be kept strictly constant, transmission of vibrations and the like can be reduced, and low noise and always stable performance can be ensured.
[0050]
The bearing 8 is arranged in a space for preventing malfunction between the Hall IC 17 (detection means) and the coil 15, whereby the overall length of the rotor 10 can be shortened, and as a result, the brushless motor The overall length can be shortened.
[0051]
The bearing 8 is arranged in a space for preventing malfunction between the Hall IC 17 (detection means) and the coil 15, and when the bearing 8 is a magnetic body, the bearing 8 is connected to the coil 15. Therefore, the magnetic flux generated from the coil 15 has less influence on the Hall IC 17 (detection means), and the sensitivity of the Hall IC 17 (detection means) can be improved.
[0052]
The resin-molded stator 30 has an inner diameter that changes stepwise in the axial direction. That is, the inner diameter of the stator 30 has a large diameter on the opening side (worm side), and gradually changes from a large diameter to a small diameter as it advances to the back side (counter worm side).
[0053]
Therefore, after the resin molding and curing, the cored bar of the mold can be pulled out without being caught, and the mold can be smoothly cut out.
[0054]
Further, the inner diameter of the stator 30 has a large diameter on the opening side (worm side), and gradually changes from a large diameter to a small diameter as it advances to the back side (counter worm side). The rotor 10 can be inserted from the side of the opening having the maximum diameter, and the assembly workability can be improved.
[0055]
Therefore, since the brushless motor can be assembled to the worm gear mechanism after assembling, the assembly workability is not impaired, and the performance and the like can be inspected with the brushless motor alone. .
[0056]
Further, the resin-molded stator 30 is integrally molded with resin-molded wire connection terminals (connectors) 31 for terminals connected to the coil 15 and terminals for outputting signals from the Hall IC 17 (detection means). Therefore, the work of connecting the electric wire cord by soldering or the like can be eliminated, and the number of parts and the number of assembling steps can be reduced.
[0057]
Next, FIG. 2 is a longitudinal sectional view of an electric power steering apparatus according to a modification of the embodiment of the present invention.
[0058]
In this modification, a thick IC on the opposite side to the motor output side end of the stator 30 is provided with a Hall IC 17 (detection means), a substrate 18, a terminal (bus bar) 19, and a wire connection terminal (connector) 31. Is arranged.
[0059]
Further, the bearing 9 opposite to the motor output side end of the stator 30 is provided at this thick end via a cylindrical bracket 9a.
[0060]
Further, the sensing permanent magnet (detected body) 13 is installed at the end of the rotor 10 opposite to the motor output side end. Thereby, the interference part of the gear housing 3 and the electric wire connection terminal 31 can be eliminated, the shape can be simplified, dustproof and waterproof can be improved, and iron scraps and the like can be prevented from entering the interior when the motor is assembled alone. It becomes possible.
[0061]
Further, the stator 30 has a flange 33 on its outer surface for mounting on the speed reducer. Therefore, the flange 33 of the stator 30 allows the brushless motor to be mounted on the reduction gear, eliminates the need for a conventional metal motor cover and its mounting flange, and reduces the number of parts and assembly man-hours. Manufacturing cost can be reduced.
[0062]
In addition, since the flange 33 is provided near the center of the stator 30 in the axial direction, the distance between the motor center of gravity and the flange 33 can be shortened, and the force generated in the flange 33 due to vibration or the like is reduced. The required strength of 33 can be reduced, that is, the weight and size can be reduced.
[0063]
In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible.
[0064]
【The invention's effect】
As described above, according to the first aspect, since the two bearings that support the rotor rotatably are supported by the stator, the radial gap between the laminated core of the stator and the rotor is Therefore, it can be kept strictly constant, transmission of vibration and the like can be reduced, and low noise and always stable performance can be ensured.
[0065]
Moreover, since the stator covers the coil, the laminated iron core, the detection means, and the terminal and is integrally resin-molded, it can also serve as a conventional metal motor cover. Therefore, the flange provided on the stator allows the brushless motor to be mounted on the reduction gear, eliminates the need for a conventional metal motor cover, and reduces the number of parts and assembly man-hours. Manufacturing cost can be reduced.
[0066]
According to a second aspect of the present invention, the stator closes the opening on the anti-reduction gear side and has a blocking wall for holding one of the two bearings. Therefore, this one bearing can be easily attached to the blocking wall.
[0067]
Further, according to the third aspect, the other of the two bearings is disposed on the inner diameter side of the stator and between the rotation driving permanent magnet and the detected body. In other words, the bearing is arranged in a space for preventing malfunction between the detection means and the coil, so that the overall length of the rotor can be shortened, and thus the overall length of the brushless motor can be shortened. Can do.
[0068]
Further, the bearing is arranged in a space for preventing malfunction between the detection means and the coil, and when the bearing is a magnetic body, the bearing forms a magnetic path for confining the magnetic flux from the coil. Therefore, the influence of the magnetic flux generated from the coil on the detection means is reduced, and the sensitivity of the detection means can be improved.
[0069]
According to a fourth aspect of the present invention, the inner diameter of the stator changes stepwise in the axial direction. That is, the inner diameter of the stator has a large diameter on the opening side, and gradually changes from a large diameter to a small diameter as it advances toward the back side. Therefore, after the resin molding and curing, the cored bar of the mold can be pulled out without being caught, and the mold can be smoothly cut out.
[0070]
The stator has an inner diameter that changes stepwise in the axial direction. That is, the inner diameter of the stator has a large diameter on the opening side, and gradually changes from a large diameter to a small diameter as it advances toward the back side. Therefore, the rotor to which the bearing is attached can be inserted from the opening side having the maximum diameter, and the assembly workability can be improved.
[0071]
Therefore, since the brushless motor can be assembled to the speed reducer after assembling, the assembly workability is not impaired, and the performance and the like can be inspected with the brushless motor alone. .
[0072]
Furthermore, according to the fifth aspect, the stator integrally has the electric wire connection terminal. That is, since the stator is integrally formed with the terminal connected to the coil and the wire connecting terminal (connector) for outputting the signal of the detecting means, the conventional wire cord is soldered or the like. The work that has been connected can be made unnecessary, and the number of parts and the number of assembly steps can be reduced.
[0073]
According to the sixth aspect of the present invention, the stator has a flange on the outer surface thereof for mounting on the reduction gear. Therefore, this stator flange allows the brushless motor to be mounted on the reduction gear, eliminates the need for a conventional metal motor cover and its mounting flange, and reduces the number of parts and assembly man-hours. Manufacturing cost can be reduced. Furthermore, since this flange is provided in the vicinity of the center of the stator shaft in the longitudinal direction, the distance between the motor center of gravity and the flange can be shortened, and the force generated in the flange due to vibration or the like is reduced, thereby reducing the required strength of the flange. That is, the weight and size can be reduced.
[0074]
Furthermore, according to claim 7, by providing the detected body at the rotor end opposite to the motor output side end, the interference portion between the gear housing and the electric wire connection terminal is eliminated, the shape is simplified, dust proof, It is possible to improve the waterproof property, and it is possible to prevent the entry of iron scrap or the like into the interior of the motor assembly alone.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an electric power steering apparatus according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of an electric power steering apparatus according to a modification of the embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of a conventional electric power steering apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Output shaft 2 Worm wheel 3 Gear housing 4 Bearing 5 Worm 6 Flange 7 Motor cover 8 Bearing 9 Bearing 9a Cylindrical bracket 10 Rotor 11 Spline fitting part 12 Rotation drive permanent magnet 13 Sensing permanent magnet (detected body)
15 coil 16 laminated iron core 17 Hall IC (detection means)
18 Board 19 Terminal (Bus Bar)
20 Electric wire cord 30 Stator 31 Electric wire connection terminal (connector)
33 Flange 34 Cylindrical bracket 35 Closure wall 36 Recess

Claims (7)

In the electric power steering device that generates auxiliary steering torque from the brushless motor in response to the steering torque applied to the steering wheel, decelerates it by the reduction gear, and transmits it to the output shaft of the steering mechanism.
The rotor is provided with a cylindrical rotational driving permanent magnet and a detected body for detecting the rotation angle of the rotor,
A cylindrical stator facing the rotor has a resin core integrally formed with a laminated iron core around which a coil is wound, a detecting means for detecting a rotation angle of the rotor from the detected body, and a terminal for connecting the coil. Molded,
The electric power steering apparatus, wherein the two bearings that rotatably support the rotor are supported by the stator. 2. The electric power steering apparatus according to claim 1, wherein the stator has an obstruction wall for obstructing an opening on an anti-reduction gear side and holding one of the two bearings. The other of the two bearings is disposed on the inner diameter side of the stator and between the rotation driving permanent magnet and the detected body. 2. The electric power steering apparatus according to 2. 4. The electric power steering apparatus according to claim 1, wherein an inner diameter of the stator changes stepwise in the axial direction. 5. The electric power steering apparatus according to any one of claims 1 to 4, wherein the stator has an electric wire connection terminal integrally. 6. The stator according to claim 1, wherein the stator has a flange for mounting on the speed reducer on an outer surface thereof, and the flange is disposed in the vicinity of the center of the stator in the longitudinal direction of the stator. The electric power steering device according to the item. The electric power steering apparatus according to any one of claims 1 to 6, wherein the detected object is installed at a rotor end opposite to a motor output side end.

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