JP2008067552A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce oscillating sound and striking sound, which are generated from respective parts, by securely showing a damping function for a plurality of damping generation sources. <P>SOLUTION: A clearance is made between a bearing 40 and a first support part 24A, which are fitted to a rear-side rotor shaft 32R in a motor 12, and a clearance is also made between a bearing 52 and a second support part 48B, which are fitted to a front-side shaft 32F. Thus, rolling of a rotor shaft 32 due to tolerance of spline engagement of a boss part 50 can be reduced. O rings 40 and 54 are installed between the clearances. Thus, alignment property at normal time can be maintained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention accommodates a rotor and a stator so that they are coaxial with each other and have a predetermined relative positional relationship, and supports a rotor shaft that extends through the shaft center of the rotor and extends in one direction via a bearing. Motor having a housing unit including a first support portion that rotates, and a second support portion that rotatably supports a rotor shaft that extends through the shaft axis of the rotor to the other via a bearing It is about.

  2. Description of the Related Art Conventionally, for example, a motor applied as a drive source for an electric power steering device for a vehicle includes a cylindrical stator and a lid member that closes the opening side of the housing, and a cylindrical stator. A rotor disposed coaxially and rotatably inside is accommodated.

  The rotor shaft extending coaxially through the rotor axis rolls on each of the first bearing support portion provided on the bottom side of the housing and the second bearing support portion provided on the lid member. It is supported via a bearing (ball bearing).

  By the way, in the conventional motor described above, a predetermined gap is intentionally provided between the ball bearing and a housing or lid member (hereinafter collectively referred to as “housing etc.”) that supports the ball bearing. To improve work efficiency during assembly. However, in such a structure, the structure in which the radial direction of the ball bearing cannot be reliably supported becomes unbalanced, and the rotor itself is unbalanced, or the vibration generated due to the backlash propagates to the ball bearing, and the operation noise And leaks to the outside.

  In this case, the motor applied to the electric power steering device has a great influence on the noise noise of the entire vehicle, so the motor is manufactured with extremely severe parts accuracy and aligned with high accuracy ( Alignment) is required.

  Therefore, Patent Documents 1 to 3 propose that a vibration absorbing material, a collision preventing member, an O-ring, and the like are interposed between the outer ring of the ball bearing and a housing that supports the outer ring.

Thereby, when the motor is operated, it is possible to reduce the sound (sounding sound) of the ball bearing hitting the hung jig or the like.
Japanese Patent Laid-Open No. 11-252851 JP 2000-166169 A JP 2002-101608 A

  However, the cause of the noise is not only the rear side ball bearing (usually the ball bearing corresponding to the bottom side of the housing) and the hitting sound of the housing, but also the motor output shaft of the electric power steering device, the deceleration Since the mechanism is spline-fitted, there is a noise caused by the meshing tolerance when the spline is fitted, and a sound caused by rolling (rolling) of the rear ball bearing due to the radial force generated by the misalignment. It is not sufficient to simply interpose a vibration absorbing material, a collision preventing material, an O-ring, or the like.

  In consideration of the above facts, the present invention has an object to obtain a motor that can reduce vibration sound and tapping sound generated from each part by reliably exhibiting a vibration suppression function for a plurality of vibration generation sources. It is.

  The present invention accommodates a rotor and a stator so that they are coaxial with each other and have a predetermined relative positional relationship, and a rotor shaft that extends through the shaft center of the rotor and extends to one side can be rotated via a bearing. A housing unit including a first support portion for supporting, and a second support portion for rotatably supporting a rotor shaft extending through the shaft center of the rotor to the other via a bearing is provided. The motor is characterized in that a predetermined gap is provided between each of the first support portion and the bearing and between the second support portion and the bearing.

  According to the present invention, in the first support portion and the second support portion that rotatably support the respective rotor shafts that extend from both ends through the shaft center of the rotor via the bearings, Assembling workability is improved by providing a gap therebetween.

  In addition, since the two support points both have a predetermined gap, it is possible to reduce propagation of vibration when the rotor is driven. Further, rolling around one support point is difficult to occur, and the hitting sound can be reduced.

  In the present invention, a cushioning material is interposed in the gap. By interposing a cushioning material in the gap, it is possible to achieve both improved assembly workability and ease of alignment work. In the present invention, the cushioning material is an O-ring. By applying an O-ring as a buffer material, the first support member and the second support member can be supported with uniform force over the entire circumferential direction of the bearing, and alignment accuracy can be maintained. it can.

  Furthermore, in the present invention, the O-ring is provided at a plurality of locations in the axial direction on the outer periphery of the bearing, and the elastic coefficient or rubber hardness of each O-ring is different. For example, when there is a possibility that the rotor shaft may cause rolling, the rolling can be suppressed by adjusting the elastic coefficient or rubber hardness of the O-rings provided at different positions in the axial direction.

  Further, the motor of the present invention is characterized in that it is applied as a drive source of an electric power steering device that assists an operating force during steering of a vehicle.

  In the motor applied to the electric power steering apparatus, the operation sound has a great influence on the noise sound of the entire vehicle. For this reason, it has been necessary to manufacture the motor that causes this noise sound with the accuracy of extremely severe parts and to perform alignment (alignment) with high accuracy. When the first support portion and the second support portion are supported via the first support portion and the second support portion, a predetermined gap is provided between the first support portion and the second support portion, respectively. The spline fitting is connected to the speed reduction mechanism that constitutes a part of the electric power steering, and the rolling of the rotor shaft that can occur when the fitting rattles (within the tolerance) can be suppressed.

  As described above, the present invention has an excellent effect that vibration sound and tapping sound generated from each part can be reduced by reliably exhibiting a vibration damping function with respect to a plurality of vibration generation sources.

  FIG. 1 shows an electric power steering apparatus 10 according to the present embodiment. The electric power steering apparatus 10 is applied with the motor 12 of the present invention as a drive source.

  As shown in FIGS. 1 and 2, the electric power steering apparatus 10 is attached to the tip of a steering shaft 16 provided along the axis of the steering wheel 14, and the motor 12 and the driving force of the motor 12 are mounted. And a speed reducer 18 that decelerates and transmits the speed to the steering wheel 16.

  The motor 12 is driven based on a detection signal from a torque sensor (not shown) that detects an operation force during steering by the steering wheel 14, and assists (assists) the rotation of the steering shaft 16.

  As shown in FIG. 2, the speed reducer 18 is engaged with a worm gear 20 coaxially connected to an output shaft (a front rotor shaft 32F (see FIG. 3) described later) from the motor 12, and the worm gear 20. The wheel gear 22 is coaxially attached to the steering shaft 16. When power is transmitted from the worm gear 20 to the wheel gear 22, a predetermined deceleration is performed with respect to the rotational speed of the output shaft of the motor 12.

  As shown in FIG. 3, the periphery of the motor 12 is covered with a housing 24. The housing 24 has a bottomed cylindrical shape, and a cylindrical stator core 26 is attached to the inner peripheral surface thereof. A coil 28 is wound around the stator core 26 and is alternately excited to the N pole and the S pole by energization.

  A rotor core 30 is accommodated inside the stator core 26 and is disposed coaxially with the stator core 26. The rotor core 30 has a shaft extending through the rotor shaft 32 and extends from both ends of the rotor core 30 in the axial direction.

  A magnet 34 is attached to the outer periphery of the rotor core 30 so as to face the stator core 26 at a predetermined interval. The magnet 34 is covered with a magnet cover 36 on the outer periphery.

  Of the rotor shafts 32 protruding from the rotor core 30, the rotor shaft protruding to the bottom side of the housing 24 (hereinafter referred to as a rear-side rotor shaft 32 </ b> R) has a small-diameter cylindrical shape whose tip is formed in the housing 24. The first support portion 24A is housed. An inner ring 39A of a ball bearing (rolling bearing) 38 as a bearing is fitted to the tip of the rear rotor shaft 32R. 39B is a ball as a rolling element.

  As shown in FIG. 4, the outer periphery of the outer ring 39 of the ball bearing 38 faces the inner peripheral surface 41 of the first support portion 24 </ b> A, and a predetermined gap is formed therebetween. That is, when the outer diameter φ1 of the outer ring 39 of the ball bearing 38 is compared with the inner diameter φ2 of the inner peripheral surface of the first support portion 24A, the relationship is φ1 <φ2.

  Further, two streaky grooves 38A are formed on the outer periphery of the outer ring 39 of the ball bearing 38, and a part of the O-ring 40 as a buffer material is accommodated. As a result, the other part of the O-ring 40 protrudes from the outer periphery of the outer ring of the ball bearing 38 and comes into contact with the inner periphery of the first support portion 24A. In other words, the ball bearing 38 is tightly accommodated in the first support portion 24 </ b> A via the O-ring 40.

  On the other hand, of the rotor shaft 32 protruding from the rotor core 30, the rotor shaft protruding to the opening side of the housing 24 (hereinafter referred to as the front-side rotor shaft 32F) is fitted with a resolver rotor 42 at its protruding intermediate portion, and the terminal block It is opposed to a resolver stator 46 attached to 44.

  The front rotor shaft 32F passes through a through hole 48A provided in the shaft core of a lid member 48 (also serving as a flange) that closes the opening of the housing 24 in the vicinity of the opening of the housing 24. It is extended to the boss | hub part 50 for connecting with.

  The peripheral edge of the through hole 48 </ b> A constitutes a second support portion 48 </ b> B, and supports the front-side rotor shaft 32 </ b> F via a ball bearing 52 in a rotatable manner.

  That is, the inner ring of the ball bearing 52 is fitted to the front rotor shaft 32F, and the outer periphery of the outer ring of the ball bearing 52 is opposed to the inner peripheral surface of the second support portion 48B. A predetermined gap is formed between the outer periphery of the outer ring 51 of the ball bearing 52 and the inner peripheral surface of the second support portion 48B facing the outer ring 51, similarly to the rear rotor shaft 32R.

  Further, two streak-like grooves 52A are formed on the outer periphery of the outer ring of the ball bearing 52, and a part of the O-ring 54 as a cushioning material is accommodated. As a result, the other part of the O-ring 54 protrudes from the outer periphery of the outer ring of the ball bearing 52 and comes into contact with the inner periphery of the second support portion 48B. In other words, the ball bearing 52 is tightly accommodated in the second support portion 48 </ b> B via the O-ring 54. A streak-like groove is formed on the entire front end of the front shaft 32F, and the boss portion 50 is spline-fitted.

  The operation of this embodiment will be described below. The electric power steering device 10 functions when the steering wheel 14 is operated (steered). That is, when the steering wheel 14 is steered, the operating force at the time of steering is detected by a torque sensor.

  The detection signal of the torque sensor is input to, for example, a power steering computer, calculates the rotation angle signal of the motor 12, and sends it to the motor 12. The motor 12 is driven based on the input rotation angle signal. The driving force of the motor 12 is transmitted to the steering shaft 16 via the speed reducer 18, and the steering shaft 16 is rotated so as to assist the steering wheel 14.

In the motor 12 having the above-described configuration, the present embodiment is characterized in that a predetermined gap (φ ₂ −φ ₁ ) is provided in both the first support portion 24A and the bearing 38, and the second support portion 48B and the bearing 52. It is in the point provided. The gap is preferably 10 μm or less.

  In general, the bearing structure on the output side, that is, the front side rotor shaft 32F, is fitted with no gap between the bearing 52 and the second support portion 48B in order to suppress misalignment as much as possible. In this case, although the alignment state is maintained with the motor 12 alone, when assembled as the electric power steering device 10, the rotor shaft is loosened by the backlash due to the spline tooth meshing tolerance in the spline-fitted boss portion 50. As a result, the tapping noise may occur between the bearing 38 supporting the rear rotor shaft 32R and the first support portion 24A.

Therefore, in the present embodiment, in addition to the rear rotor shaft 32R and the bearing 38, the front rotor shaft 32F and the bearing 52 also have a predetermined clearance (Δφ =
The rolling was suppressed by forming φ ₂ −φ ₁ ).

  In addition, O-rings 40 and 54 are interposed in the gap, and the alignment state of the bearings 38 and 52 is maintained by the O-rings 40 and 54 in a steady state (including stable driving and non-driving). Therefore, unnecessary misalignment does not occur.

  Further, in the present embodiment, since the two O-rings 40 and 54 are shifted in the axial direction with respect to the respective bearings 38 and 52, the rotational shake at the steady state is further reduced.

  The O-rings 40 and 54 in the present embodiment all have the same physical properties, but in order to suppress rolling, the elastic coefficient and rubber hardness of the respective O-rings 40 and 54 are changed, It is good also as a structure which arrange | positions O-rings 40 and 54 of a respectively different physical property in a suitable material right place.

  Next, another embodiment of the present invention will be described with reference to FIG. This embodiment differs from the embodiment described with reference to FIGS. 3 and 4 described above in that the resolver is formed on the rear side and the housing (yoke) is divided into two parts such as 24A and 24B. It is that you are. In the embodiment of FIG. 5 as well, there is a predetermined gap between the outer peripheral surface of the bearing on the rear side and the inner peripheral surface of the support member facing the rear bearing, and the inner surface of the support member facing the outer peripheral surface of the front side bearing. There is a predetermined gap between the peripheral surface.

  According to the embodiment described above, in addition to providing a gap between the bearing 38 attached to the rear rotor shaft 32R and the first support portion 24A in the motor 12, the bearing attached to the front shaft 32F. By providing a similar gap between the second support portion 48B and the second support portion 48B, it is possible to reduce the rolling of the rotor shaft 32 due to the meshing tolerance of the spline fitting of the boss portion 50. Further, by providing the O-rings 40 and 54 in the gap, it is possible to maintain the alignment property in the steady state. Note that the gap on the rear side and the gap on the front side may be the same or substantially different. In an electric power steering motor, the size of the front bearing and the rear bearing is often changed, so that the gap on the front side and the rear side may be different.

1 is a perspective view of a steering assembly to which an electric power steering apparatus according to an embodiment is applied. It is a front view of the motor and reduction gear which are the electric power steering devices concerning this embodiment. It is sectional drawing which shows the internal structure of the motor which concerns on this Embodiment. It is the IV section enlarged view of FIG. It is sectional drawing which shows the internal structure of the motor which concerns on other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power steering apparatus 12 Motor 14 Steering wheel 16 Steering shaft 18 Reduction gear 20 Worm gear 22 Wheel gear 24 Housing (housing unit)
24A 1st support part 26 Stator core (stator)
28 Coil (stator)
30 Rotor core (rotor)
32 rotor shaft 32F front rotor shaft 32R rear rotor shaft 34 magnet (rotor)
36 Magnet cover (rotor)
38 Ball bearing
38A groove 40 O-ring (buffer material)
42 Resolver rotor 44 Terminal block 46 Resolver stator 48 Lid member (housing unit)
48A Through-hole 48B 2nd support part 50 Boss part 52 Ball bearing (bearing)
52A Groove 54 O-ring (buffer material)

Claims (5)

A rotor and a stator are accommodated so as to be coaxial with each other and have a predetermined relative positional relationship, and a rotor shaft extending through one through the shaft core of the rotor is rotatably supported via a bearing. A support part of
A second support portion that rotatably supports a rotor shaft that extends through the axis of the rotor and extends to the other through a bearing;
A motor comprising a housing unit comprising
A motor provided with predetermined gaps between the first support portion and the bearing and between the second support portion and the bearing.   The motor according to claim 1, wherein a buffer material is interposed in the gap.   The motor according to claim 2, wherein the cushioning material is an O-ring.   The motor according to claim 3, wherein the O-ring is provided at a plurality of different locations in the axial direction on the outer periphery of the bearing, and each O-ring has a different elastic coefficient or rubber hardness.   The motor according to any one of claims 1 to 4, wherein the motor is applied as a drive source of an electric power steering device that assists an operating force during steering of a vehicle.

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