JP2012039714A - Housing ring, motor, and electric power steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a housing ring capable of more effectively reducing motor vibrations by suppressing resonance.SOLUTION: A motor 10 comprises a housing ring 30 that is fitted to an outer periphery of a housing 11 in a position corresponding to a radial outside of a stator 12. The housing ring 30 is formed in such a manner that its rigidity is uneven in a circumferential direction.

Description

  The present invention relates to a housing ring fitted on the outer periphery of a motor housing, a motor including the housing ring, and an electric power steering apparatus including the motor.

  2. Description of the Related Art Conventionally, power steering apparatuses for vehicles include an electric power steering apparatus (EPS) using a motor as a drive source. And since such EPS has many advantages such as excellent energy efficiency, high controllability and layout flexibility, its adoption has been widely promoted in recent years.

  Now, in EPS in which high silence is required, suppressing the motor vibration is one of the most important issues. In particular, in a brushless motor, the stator is likely to be distorted (deformed) due to a magnetic attractive force during driving. For this reason, a configuration is generally used in which the stator is fixed in a housing (case) and the rigidity including the housing is reinforced, thereby suppressing the distortion of the stator as described above and improving the quietness. .

  However, a vehicle is strongly required to reduce its size and weight as well as improve its quietness. For this reason, the rigidity enhancement by the housing as described above is also naturally restricted by its outer shape (motor diameter) and weight.

  Therefore, for example, a ring member as disclosed in Patent Document 1 is fitted to the outer periphery of the housing. By disposing the ring member on the outer side in the radial direction of the stator, it is possible to effectively strengthen the rigidity around the stator while suppressing an increase in motor diameter and weight.

Japanese Patent Laid-Open No. 11-30170

  However, even when the ring member (housing ring) as described above is used, as long as there are restrictions on the outer shape and weight, the distortion caused by the magnetic attraction force when driving the motor cannot be completely suppressed. Further, the housing ring has a light weight as a single unit, and therefore, the influence of resonance tends to be obvious. For this reason, the noise level may increase in a specific frequency (resonance frequency) band, and there is still room for improvement in this respect.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a housing ring, a motor, and an electric power steering capable of reducing motor vibration more effectively by suppressing resonance. To provide an apparatus.

  In order to solve the above problems, the invention described in claim 1 is a housing ring that is fitted to the outer periphery of the motor housing, and is characterized in that the rigidity is formed unevenly in the circumferential direction. To do.

  That is, when the same distortion (deformation) occurs at each position in the circumferential direction, the vibration of the housing ring is amplified, and the influence of the resonance is easily manifested. In this regard, according to the above configuration, the deformation of the housing ring caused by the magnetic attraction force when the motor is driven becomes non-uniform in the circumferential direction. As a result, the vibration of the housing ring can be suppressed and the motor vibration can be effectively suppressed.

The gist of the invention described in claim 2 is that it has a plurality of high-rigidity portions provided at intervals in the circumferential direction.
According to the above configuration, the rigidity of the housing ring can be easily made nonuniform in the circumferential direction.

The gist of the invention described in claim 3 is that the high-rigidity portions are formed at unequal intervals in the circumferential direction.
That is, the deformation around the stator based on the magnetic attraction force at the time of driving the motor usually causes concave portions or convex portions at substantially equal intervals in the circumferential direction. Therefore, according to the said structure, it can avoid that the same deformation | transformation arises simultaneously in each highly rigid part. As a result, the resonance of the housing ring can be suppressed more effectively.

The gist of the invention described in claim 4 is that the number of the high-rigidity portions is set to a value different from the divisor of the number of motor magnetic poles.
According to the said structure, it can avoid that the same deformation | transformation arises simultaneously in all each highly rigid part with a simple structure. As a result, the resonance of the housing ring can be suppressed easily and effectively.

The gist of the invention described in claim 5 is that the rigidity at each position in the circumferential direction is set by the thickness.
The gist of the invention described in claim 6 is that the rigidity at each position in the circumferential direction is set by the ring width.

The gist of the invention described in claim 7 is that the rigidity at each position in the circumferential direction is set by heat treatment.
According to each said structure, the rigidity of each position of the circumferential direction can be changed easily and reliably.

The gist of an eighth aspect of the invention is that the motor includes the housing ring according to any one of the first to seventh aspects.
According to the above configuration, it is possible to provide a motor with high silence while suppressing vibration.

The gist of the invention described in claim 9 is an electric power steering apparatus including the motor according to claim 8.
According to the above configuration, it is possible to provide an electric power steering device that suppresses motor vibration and has high silence.

  According to the present invention, it is possible to provide a housing ring, a motor, and an electric power steering device that can suppress resonance and reduce motor vibration more effectively.

The schematic block diagram of an electric power steering device (EPS). Sectional drawing of the motor with which the housing ring was mounted | worn. The perspective view of the motor with which the housing ring was mounted | worn. The top view of a housing ring. The perspective view of the motor with which the housing ring of another example was mounted | worn. The expanded view of the housing ring of another example.

Hereinafter, an embodiment in which the present invention is embodied in a housing ring mounted on a motor of an electric power steering apparatus (EPS) will be described with reference to the drawings.
As shown in FIG. 1, in the EPS 1 of the present embodiment, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. The rotation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. Then, the reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 6 connected to both ends of the rack shaft 5, whereby the steering angle of the steered wheels 7. Is changed.

  The steering shaft 3 of the present embodiment is formed by connecting a column shaft 3a, an intermediate shaft 3b, and a pinion shaft 3c. The EPS 1 of the present embodiment is configured as a so-called column-type EPS that rotationally drives the column shaft 3a using the motor 10 as a drive source.

  That is, the EPS 1 of the present embodiment decelerates the rotation of the motor 10 by the speed reduction mechanism 9 and transmits it to the steering shaft 3 (column shaft 3a). Thus, the motor torque is applied to the steering system as an assist force.

Next, the configuration of the motor 10 in the EPS 1 of the present embodiment will be described.
As shown in FIG. 2, the motor 10 according to the present embodiment is configured as a brushless motor including a stator 12 housed in a housing 11 and a rotor 13 that is rotatably supported on the radially inner side of the stator 12. Has been.

  More specifically, the stator 12 includes an annular portion 14 fixed to the inner periphery of the substantially cylindrical housing 11 and a plurality of teeth 15 extending radially inward from the annular portion 14. . Specifically, the stator 12 of the present embodiment includes “12” teeth 15 that are evenly arranged over the entire circumference of the annular portion 14. A motor coil 17 is wound around each of the teeth 15.

  Note that the stator 12 of this embodiment has a so-called split core connection type configuration in which a plurality of split cores having a shape obtained by splitting the annular portion 14 for each tooth 15 are connected in an annular shape. The stator 12 is housed in the housing 11 with the outer periphery (the outer periphery of the annular portion 14) being fixed to the inner periphery of the housing 11 by being press-fitted in the axial direction.

  On the other hand, as shown in FIGS. 2 and 3, the rotor 13 is formed by fixing a magnet 23 on the outer periphery of a rotor core 22 that rotates together with the rotating shaft 21. Specifically, a cylindrical ring magnet is used for the magnet 23 of the present embodiment, and a “10 poles” magnetic pole is formed on the outer periphery of the magnet 23 by magnetization. The rotor 13 is rotatably supported inside the stator 12 by the rotation shaft 21 being pivotally supported by a bearing (not shown) provided in the housing 11.

  That is, the rotor 13 rotates based on the relationship between the field magnetic flux formed by each magnetic pole of the magnet 23 and the rotating magnetic field formed on the stator 12 side. The motor 10 according to the present embodiment can take out motor torque generated by the rotation of the rotor 13 by using one end of the rotating shaft 21 protruding outside from the axial end portion of the housing 11 as an output portion. Yes.

(Strengthened structure with housing ring)
Next, the rigidity reinforcement structure using the housing ring in the motor of this embodiment will be described.

  As shown in FIGS. 2 and 3, in the motor 10 of this embodiment, a substantially cylindrical housing ring 30 is fitted on the outer periphery of the housing 11. Specifically, the housing ring 30 of the present embodiment is formed of metal, and the housing ring 30 is press-fitted from the axial direction, so that the housing ring 30 is positioned at a position corresponding to the outer side in the radial direction of the stator 12. The housing 11 is externally fitted. In this embodiment, the rigidity around the stator 12 is thereby strengthened, and the distortion (deformation) of the stator 12 and the housing 11 that occurs when the motor is driven is suppressed, thereby improving the quietness by reducing the motor vibration. It has been.

  Specifically, as shown in FIGS. 2 to 4, the housing ring 30 of the present embodiment has a plurality of high-rigidity portions 31 provided at intervals in the circumferential direction. In this embodiment, the rigidity of the housing ring 30 is set to be non-uniform in the circumferential direction.

  Specifically, in the present embodiment, each high-rigidity portion 31 has a thickness (thickness at the center position in the circumferential direction) D1 thicker than a thickness D0 (basic thickness of the housing ring 30) of other portions. It is formed by setting. In the present embodiment, each high-rigidity portion 31 has the thickest circumferential center position (thickness D1) and gradually increases in thickness toward the peripheral portion (both sides in the circumferential direction) of each high-rigidity portion 31. It is formed to be thin. Further, the number (n) of each high-rigidity portion 31 is “9”, which is one less than “10” which is the number of magnetic poles 32 (the number of motor magnetic poles: p) set on the rotor 13 (magnet 23) of the motor 10. (N = p−1). In the present embodiment, the high-rigidity portions 31 are formed such that the intervals (two adjacent intervals) La to Li in the circumferential direction are unequal.

Next, the operation and effect of the housing ring of the present embodiment configured as described above will be described.
(1) The motor 10 includes a housing ring 30 fitted to the outer periphery of the housing 11 at a position corresponding to the radially outer side of the stator 12. The housing ring 30 is formed such that its rigidity is not uniform in the circumferential direction.

  That is, when the same distortion (deformation) occurs at each position in the circumferential direction, the vibration of the housing ring 30 is amplified, and the influence of the resonance is easily manifested. In this regard, according to the above configuration, the deformation of the housing ring 30 caused by the magnetic attractive force when the motor is driven becomes non-uniform in the circumferential direction. As a result, resonance of the housing ring 30 can be suppressed and motor vibration can be effectively suppressed.

  (2) The housing ring 30 has a plurality of high-rigidity portions 31 provided at intervals in the circumferential direction. Thereby, the rigidity of the housing ring 30 can be easily made nonuniform in the circumferential direction.

  (3) As shown in FIG. 4, each high-rigidity portion 31 is formed such that the intervals La to Li in the circumferential direction are unequal. That is, the deformation around the stator 12 based on the magnetic attraction force at the time of driving the motor usually causes recesses or protrusions at substantially equal intervals in the circumferential direction. Therefore, according to the above configuration, it is possible to avoid the same deformation from occurring in each high-rigidity portion 31 at the same time. As a result, the resonance of the housing ring 30 can be suppressed more effectively.

  (4) The number (n) of each high-rigidity portion 31 is one less than the number of magnetic poles 32 (the number of motor magnetic poles (p), p = 10) set on the rotor 13 (magnet 23) of the motor 10. (N = 9) is set (n = p−1). Thus, it is possible to avoid the same deformation from occurring in all the high rigidity portions 31 at the same time. As a result, the resonance of the housing ring 30 can be suppressed easily and effectively.

  (5) Each high-rigidity portion 31 is formed by setting its thickness (thickness at the center position in the circumferential direction) D1 to be thicker than the thickness D0 (basic thickness of the housing ring 30) of other portions. . As a result, it is possible to easily and surely form a portion having a higher rigidity than the other portions (i.e., not easily deformed), that is, a high rigidity portion.

In addition, you may change the said embodiment as follows.
In each of the above embodiments, the present invention is embodied in the housing ring 30 of the motor 10 that is used as the driving source of the EPS 1. However, the present invention is not limited thereto, and the present invention may be applied to a motor housing ring used for purposes other than EPS. And even if it is a case where it implements in EPS, you may apply not only to column type EPS as shown in the said embodiment but to rack type and pinion type EPS.

  In the above embodiment, the motor 10 is a brushless motor in which the stator 12 having the motor coil 17 is fixed in the housing 11. However, the present invention is not limited to this, and the present invention may be applied to a DC motor with a brush whose motor housing constitutes a yoke.

  In the above embodiment, each high-rigidity portion 31 has its thickness (thickness at the center position in the circumferential direction) D1 set to be thicker than the thickness D0 (basic thickness of the housing ring 30) of other portions. It was decided to be formed. However, not limited to this, like the housing ring 40 shown in FIG. 5, the ring width (the length in the motor axial direction (vertical direction in the figure) when mounted) W1 of each high-rigidity portion 41 is set to other portions. It is good also as a structure set relatively longer than the ring width W0. Thereby, the height of the relative rigidity can be further strengthened. And it is good also as a structure which forms each highly rigid part by setting the ring width W1 relatively longer than the ring width W0 of another part, without changing thickness. Even if it does in this way, a highly rigid part can be formed easily and reliably.

  In the configuration in which the high rigidity portion 51 is formed by setting the ring width as in the housing ring 50 shown in the development view of FIG. 6, the circumferential direction of each high rigidity portion 51 having the widest ring width W1 It is preferable that the ring width gradually change in the circumferential direction from the central portion to the peripheral portion of each of the high rigidity portions 51 having the narrowest ring width W0.

  -Furthermore, when the housing ring is formed with metal, it is good also as a structure which sets the rigidity of each position of the circumferential direction by heat processing (quenching or annealing). And the setting of the rigidity at each position in the circumferential direction, that is, the formation of each high-rigidity part is one of the setting of the thickness of the housing ring, the setting of the ring width, and the execution of the heat treatment, or It is good also as a structure performed by these arbitrary combinations.

  In the above embodiment, the number (n) of each high-rigidity portion 31 is set to a value that is one less than the number of motor magnetic poles (p) (n = p−1). However, the present invention is not limited to this, and the number (n) of each high-rigidity portion 31 may be a value different from the divisor of the number of motor magnetic poles (p) (p ≠ α × n, where “α” is an integer). . For example, if the number of motor magnetic poles (p) is “10”, the number (n) of each high-rigidity portion 51 is set to the number of motor magnetic poles (p) as in the housing ring 50 shown in FIG. One more than “11” may be set (n = p + 1). Even with such a configuration, it is possible to avoid the same deformation at the same time in all the high rigidity portions.

  In the above embodiment, the motor 10 is a 10 pole 12 slot brushless motor. However, the present invention is not limited to this, and any combination may be used for the number of motor magnetic poles (p) and the number of slots.

  In the above-described embodiment, the high-rigidity portions 31 are formed such that the intervals La to Li in the circumferential direction are unequal, but not all of them are necessarily unequal intervals. However, it is desirable to set the circumferential position of each high-rigidity part so as to avoid the occurrence of the same deformation in each high-rigidity part as much as possible.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus (EPS), 10 ... Motor, 11 ... Housing, 12 ... Stator, 13 ... Rotor, 23 ... Magnet, 30, 40, 50 ... Housing ring, 31, 41, 51 ... High rigidity part, 32 ... magnetic poles, D0, D1 ... thickness, W0, W1 ... ring width, n ... number of high-rigidity parts, p ... number of motor magnetic poles, La to Li ... intervals.

Claims (9)

A housing ring fitted on the outer periphery of the motor housing,
The rigidity is unevenly formed in the circumferential direction;
Housing ring characterized by The housing ring according to claim 1,
Having a plurality of highly rigid portions provided at intervals in the circumferential direction;
Housing ring characterized by The housing ring according to claim 2,
Each of the high rigidity portions is formed at unequal intervals in the circumferential direction,
Housing ring characterized by The housing ring according to claim 2 or claim 3,
The number of the high-rigidity parts is set to a value different from the divisor of the number of motor magnetic poles,
Housing ring characterized by In the housing ring as described in any one of Claims 1-4,
The rigidity at each position in the circumferential direction is set by the thickness,
Housing ring characterized by In the housing ring as described in any one of Claims 1-5,
The rigidity of each circumferential position is set by the ring width,
Housing ring characterized by In the housing ring as described in any one of Claims 1-6,
The rigidity at each position in the circumferential direction is set by heat treatment,
Housing ring characterized by   The motor provided with the housing ring as described in any one of Claims 1-7.   An electric power steering apparatus comprising the motor according to claim 8.

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