JP2008072822A - Electric motor with speed reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow the eccentricity due to the not so good concentricity or not so good assembly of a bearing by simple assembly method. <P>SOLUTION: In an electric motor with a speed reducer which has a worm shaft 4 united with a motor shaft 3 and is equipped with the worm shaft within its housing 1, the worm shaft 4 is supported tiltably by a bearing holder 11 via a bearing 10. The bearing holder 11 is equipped with a magnetic body 12, and it is positioned and fixed within the housing 1 via a magnet 16 provided outside the housing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor with a speed reduction mechanism.

  2. Description of the Related Art Conventionally, an electric motor with a speed reduction mechanism used in an ERR (electric tilt / telescopic) type steering device or the like includes a motor body and a speed reduction mechanism.

  A housing that houses the speed reduction mechanism unit supports a worm shaft that is integral with the motor shaft and an output gear so as to be rotatable by bearings.

The worm shaft integrated with the motor shaft is supported by three bearings. Between the bearing and the worm shaft, there is no gap, so if the coaxiality of the three bearings is low or the assembly position accuracy to the housing is poor, the output of the electric motor will decrease, Abnormal noise occurs.
International Publication No. WO99 / 59235

  Therefore, as disclosed in Patent Document 1, there is a method of allowing the coaxial displacement of the three bearings and the misalignment due to the assembly by, for example, pressurizing the resin material in the worm axis direction after heating and softening.

  However, in this method, there are cases where assembly is not simple, for example, equipment such as heating and pressurization is required for assembly.

  The present invention has been made in view of the circumstances as described above, and provides an electric motor with a speed reduction mechanism capable of allowing the coaxiality of a bearing and misalignment due to assembly by a simple assembly method. For the purpose.

In order to achieve the above object, an electric motor with a speed reduction mechanism according to the present invention includes:
A motor shaft and a worm shaft integrated with the motor shaft, the worm shaft is provided in a housing;
The worm shaft is tiltably supported on a bearing holder via a bearing,
The bearing holder is positioned and fixed inside the housing via a magnet provided outside the housing.

In the electric motor with a speed reduction mechanism of the present invention,
The bearing holder includes a magnetic body, and a magnet holding means is provided on the outer side of the housing at a position facing the bearing holder, and the magnet holding means is screwed through the housing to come into contact with the tip of the worm shaft. It is preferable to provide.

  According to the present invention, the coaxiality of the bearing and the misalignment due to the assembly can be allowed by a simple assembling method.

  Hereinafter, an electric motor with a speed reduction mechanism according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of an electric motor with a speed reduction mechanism according to a first embodiment of the present invention.
FIG. 2 is a partially enlarged sectional view of a circled portion indicated by reference numeral “II” in FIG.

  As shown in FIG. 1, a motor body 2 is fixed to a housing 1 that houses a speed reduction mechanism, and a worm shaft 4 and an output shaft that are integrated with a motor shaft 3 are rotatably supported via bearings, respectively. Has been.

  The speed reduction mechanism is composed of a worm shaft 4 and an output gear 5 that meshes with the worm of the worm shaft 4. The bearing that rotatably supports the worm shaft 4 integrated with the motor shaft 3 in the housing includes bearings 6 and 7 provided in the motor body 2 and a bearing 10 provided in the housing 1. The bearing that supports the output shaft to which the output gear 5 is attached to the housing is not shown.

  As shown in FIG. 2, the bearing 10 provided in the housing 1 is a sliding bearing having a spherical outer peripheral surface, and is supported by a cylindrical bearing holder 11 with a bottom so as to be tiltable.

  A round hole 11 a is formed at the center of the bottom surface of the bearing holder 11. The bearing holder 11 is provided with a magnetic body 12 between the outside of the bottom surface and the inner surface of the housing, and the magnetic body 12 is also formed with a round hole 12a aligned with the round hole 11a.

  The material of the magnetic body 12 is a metal such as steel or stainless steel, and the surface roughness of contact with the housing 1 is deteriorated.

  A screw hole for mounting the bearing 10 is formed in the portion of the housing 1 that accommodates the worm shaft 4, and is screwed into the screw hole from the outside of the housing 1 toward the tip of the worm shaft 4. Screws 13 are arranged. The backlash screw 13 passes through the round hole 12a of the magnetic body 12 and the hole 11a of the bearing holder 11, contacts the tip of the worm shaft 4, and suppresses the axial play of the worm shaft 4. A loosening lock nut 14 is disposed on the backlash screw 13.

  A metal washer 15 is sandwiched between the lock nut 14 and the housing 1. A cylindrical groove 15a is formed continuously with the central hole on one side of the washer 15 that contacts the housing, and a cylindrical ferrite magnet 16 is accommodated in the cylindrical groove 15a. Yes.

  Since the ferrite magnet 16 is easily broken, the cylindrical groove 15 a is deeper than the thickness of the ferrite magnet 16, and the axial force when the lock nut 14 is tightened is not applied to the ferrite magnet 16. That is, a gap G is provided between the ferrite magnet 16 and the bottom surface of the cylindrical groove 15a.

  As a result, when the motor body 2 is assembled to the housing 1, the sliding bearing 10 and the bearing holder 11 at the tip of the worm shaft 4 are not fixed and are arranged at positions following the worm shaft 4.

  Even when the loose screw 13 is assembled in the axial direction of the worm shaft 4, the sliding bearing 10 and the bearing holder 11 at the tip of the worm shaft 4 are not fixed and are arranged at positions following the worm shaft 4.

  Finally, by attaching the ferrite magnet 16, the washer 15, and the lock nut 14 for preventing loosening, the bearing holder 11 is attracted to the housing 1 by the magnetic force of the ferrite magnet 16, and the worm shaft 4 supported by the bearing holder 11. The position of the sliding bearing 10 at the tip is fixed.

  Since the slide bearing 10 is supported to be tiltable with respect to the bearing holder 11, even when the shaft core of the worm shaft 4 and the shaft center of the bearing holder 11 are misaligned when the bearing holder 11 is attracted by a magnetic force. The worm shaft 4 is not twisted.

  Therefore, since the sliding bearing 10 at the tip of the worm shaft 4 can be disposed at a position following the worm shaft 4, it is possible to prevent a decrease in the output of the electric motor and the generation of abnormal noise. In other words, the coaxiality of the bearing and the misalignment due to the assembly can be allowed by a simple assembling method.

  Further, by reducing the surface roughness of the contact surface between the magnetic body 12 and the housing 1, the friction coefficient of the contact surface can be increased and the force for fixing the bearing holder 11 can be increased. Therefore, the ferrite magnet 16 can be reduced in size, and cost and weight can be reduced.

(Second Embodiment)
FIG. 3 is a partially enlarged sectional view of an electric motor with a speed reduction mechanism according to the second embodiment of the present invention.

  In the present embodiment, the basic configuration is the same as that of the first embodiment described above, and only differences will be described.

  In the present embodiment, the ferrite magnet 16 is disposed on the radially outer side of the metal washer 15 having a diameter larger than that of the lock nut 14.

  At this time, the thickness of the ferrite magnet 16 is made thinner than that of the washer 15, and the washer 15 and the ferrite magnet 16 are joined and integrated with, for example, an adhesive to provide a gap between the housing 1 and the first embodiment. Similarly to the embodiment, the ferrite magnet 16 has a structure in which no axial force is applied.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

(Third embodiment)
FIG. 4 is a partially enlarged sectional view of an electric motor with a speed reduction mechanism according to a third embodiment of the present invention.

  In the present embodiment, the basic configuration is the same as that of the first embodiment described above, and only differences will be described.

  In the present embodiment, the lock nut 14 is a magnet. In this case, since an axial force is applied to the lock nut 14, the lock nut 14 is a rare earth magnet having high mechanical strength.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

(Fourth embodiment)
FIG. 5 is a partially enlarged cross-sectional view of an electric motor with a speed reduction mechanism according to a fourth embodiment of the present invention.

  In the present embodiment, the basic configuration is the same as that of the first embodiment described above, and only differences will be described.

  In the present embodiment, a washer 15 is sandwiched between the lock nut 14 and the housing 1, and the washer 15 is a magnet. In this case, since an axial force is applied to the washer 15, the washer 15 is a rare earth magnet having high mechanical strength.

  Other configurations, operations, and effects are the same as those in the first embodiment described above.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible.

It is sectional drawing of the electric motor with a speed reduction mechanism which concerns on 1st Embodiment of this invention. FIG. 2 is a partially enlarged cross-sectional view of a circled portion indicated by reference numeral “II” in FIG. 1. It is a partial expanded sectional view of the electric motor with a reduction mechanism which concerns on 2nd Embodiment of this invention. It is a partial expanded sectional view of the electric motor with a reduction mechanism which concerns on 3rd Embodiment of this invention. It is a partial expanded sectional view of the electric motor with a reduction mechanism which concerns on 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Motor body 3 Motor shaft 4 Worm shaft 5 Output gear 6, 7 Bearing 6, 7
DESCRIPTION OF SYMBOLS 10 Sliding bearing 11 Bearing holder 11a Round hole 12 Magnetic body 12a Round hole 13 Backpacking screw 14 Lock nut 15 Washer 15a Cylindrical groove 16 Ferrite magnet G Gap

Claims (2)

In an electric motor with a speed reduction mechanism having a motor shaft and a worm shaft integrated with the motor shaft, and having the worm shaft in a housing,
The worm shaft is tiltably supported on a bearing holder via a bearing,
The electric motor with a speed reduction mechanism, wherein the bearing holder includes a magnetic body and is positioned and fixed in the housing via a magnet provided outside the housing.   Magnet holding means is provided on the outer side of the housing at a position opposed to the bearing holder, and the magnet holding means includes a screw that penetrates the housing and contacts the tip of the worm shaft. The electric motor with a speed reduction mechanism according to claim 1.

Images