JP2001251804A - Electric motor and electric steering apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in rotation resistance of a rotor due to a sealing ring 15e of a bearing 15 and assures returning property of a steering ring, at assembling of an electric motor and at the time of rising in temperature of the bearing 15 supporting the rotor by assisting the steering with the electric motor. SOLUTION: A bearing 15, which supports a rotor 72 to rotate at an engaging portion within a housing 70, has a sealing ring 15e for preventing leakage of a lubricating agent between an inner ring 15a and an outer ring 15b, which are engaged with play via a plurality of rolling bodies 15c. This sealing ring 15e is also provided with an inter-connecting path 17 for communicating vacant areas 7a, 7b within the housing 70, to which both ends of the bearing 15 are facing. As a result, the air in one vacant area 7a is made to escape to the other vacant area 7b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor in which a rotor is rotatably supported via a bearing in a housing provided with a stator, and an electric motor for assisting the steering of steering means using the electric motor. The present invention relates to a steering device.

[0002]

2. Description of the Related Art As an electric steering device for a vehicle, for example, a steering torque applied to an input shaft is detected by a relative angular displacement of an input shaft and an output shaft coaxially connected to the input shaft via a torsion bar. A torque sensor, a control unit that drives and controls an electric motor for steering assistance based on the torque detected by the torque sensor, and a first housing that covers the torque sensor portion, wherein The operation of the steering mechanism is assisted by the rotation of the electric motor, and the burden on the driver for steering is reduced.

FIG. 6 is an enlarged sectional view of a bearing portion of a conventional electric motor, and FIG. 7 is an explanatory view showing an assembling process of the conventional electric motor. The steering assist electric motor 100 includes a cylindrical stator 102 fixed in a bottomed cylindrical second housing 101, a rotor 103 rotatably disposed in the stator 102, A first bearing 1 fitted to both ends of the rotor 103 in the axial direction to rotatably support the rotor 103.
04 and a second bearing (not shown)
Are provided, and a first fitting portion 105 and a second fitting portion (not shown) are provided. The rotor 103 is connected to the steering shaft via a speed reduction mechanism such as a hypoid gear and the output shaft. It is connected to the taking mechanism.

[0004] The first bearing 104 is a lubricating material such as grease filled in the bearing between the rolling element 106 and both ends in the axial direction of the inner ring 107 and the outer ring 108 which are loosely fitted through the plural rolling elements 106. Rubber sealing ring 1 to prevent the agent from flowing out
09. The sealing ring 109 has its outer peripheral portion fitted and fixed to the outer ring 108, and its inner peripheral portion is arranged so as to face a radial step 110 provided at the end of the inner ring 107 in a non-contact manner.

The electric motor 100 is assembled by connecting a first bearing 1 to one end of a rotor 103 whose other end is supported by the first housing via a second bearing and a second fitting portion.
04 is fitted and fixed, a bottomed cylindrical second housing 101 in which a stator 102 is fitted and fixed to the inner peripheral surface is inserted around the outer periphery of the rotor 103, and the bottom of the housing 101 is inserted. It is assembled by fitting the first bearing 104 into the first fitting portion 105 provided on the side.

[0006]

However, in the conventional electric motor 100, a bottomed cylindrical second housing 101 is inserted around the outer periphery of the rotor 103, and the second housing 101 is attached to the bottom side of the housing 101. When the first bearing 104 is fitted to the provided first fitting portion 105, one end of the first bearing 104 comes into contact with the fitting portion 105, and an empty space between the bottom of the housing 101 and the bearing 104. Place 111 is sealed,
Since the housing 101 is inserted and fitted in this sealed space, and the volume of the sealed space is reduced, the air in the sealed space is removed until the bearing 104 is completely fitted into the fitting portion 105. The sealing ring 109 of the bearing 104 is bent by the pressurized air, and the inner peripheral portion of the sealing ring 109 is
7, the rotational resistance of the rotor 103, which rotates integrally with the inner ring 107, is increased, and the electric motor 100 is incorporated into the vehicle body while maintaining the pressed state. Therefore, there is a problem that the return resistance of the steered wheels after the electric motor 100 assists the steering is increased, and the return of the steered wheels is reduced.

Further, when the electric motor 100 assists the steering, the inner ring 107 and the outer ring 108 of the first bearing 104 rotate relative to each other, and a plurality of rolling elements 106 roll, and the temperature of the bearing 104 increases due to the frictional resistance. , The bearing 10
4, the air in the space 111 thermally expands, and the thermal expansion causes the sealing ring 109 of the bearing 104 to bend, and the inner peripheral portion of the sealing ring 109 becomes a step 110 of the inner ring 107.
, Which is pressed against the inner ring 107 and rotates integrally with the inner ring 107.
Will increase the rotational resistance. Therefore, the return resistance of the steered wheels after the electric motor 100 assists the steering increases,
There is a problem that the return of the steered wheels is reduced.

An object of the present invention is to provide an electric motor and an electric steering device which can solve the above problems.

[0009]

Means for Solving the Problems and Effects of the Invention An electric motor according to a first aspect of the present invention is an electric motor in which a bearing for supporting a rotor is fitted in a housing having a fitting portion. The bearing has a sealing ring between the inner ring and the outer ring loosely fitted via a plurality of rolling elements to prevent the lubricant from flowing out, and at least one of the bearing, the fitting portion, and the rotor is provided. One is characterized in that it is provided with a communication path for communicating the cavities facing both ends of the bearing with each other.

According to a third aspect of the present invention, there is provided an electric steering apparatus comprising: an electric motor according to claim 1 or 2; a control unit for controlling the electric motor in accordance with steering of a steering means; Transmission means for transmitting the rotational force of the motor to the steering mechanism.

According to the first and third aspects of the invention, at least one of the bearing for supporting the rotor, the fitting portion into which the bearing is fitted, and the rotor communicates with each other through the space facing both ends of the bearing. Since the communication passage is provided, when the housing of the motor is inserted around the outer periphery of the rotor, the housing can be inserted without creating a closed space by the communication passage. Therefore, it is possible to prevent the sealing ring of the bearing from being pressed against the housing due to the insertion of the housing, thereby preventing the rotation resistance of the rotor from increasing due to the sealing ring, and improving the return of the steered wheels.

In addition, the temperature of the bearing supporting the rotor rises due to the assisting of the steering by the electric motor, and the air in one of the cavities thermally expanded due to the heat generated by the bearing causes the air in one of the cavities to pass between the communication passage and the inner and outer rings. Since it is possible to escape to the other space through the space, it is possible to prevent the sealing ring from being pressed against by the thermally expanded air, and to prevent the rotation resistance of the rotor from being increased by the sealing ring. It is possible to maintain good return of the steered wheels.

An electric motor according to a second invention is characterized in that the sealing ring has the communication passage.

According to the second aspect of the present invention, by forming a communication hole in a plate portion having a relatively small thickness, a space between both ends of the bearing can be communicated with each other through a space between the inner ring and the outer ring. it can.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. 1 is a sectional view of an electric steering device according to the present invention.

The electric steering apparatus has a first steering shaft 1 whose upper end is connected to a steered wheel (not shown), and a first steering shaft 1 connected to the steering shaft 1 and the steering shaft 1 via a torsion bar 2. A torque sensor 4 for detecting a steering torque based on a relative rotational displacement of the second steering shaft 3, a pinion 5 for transmitting a torque of the second steering shaft 3 to a steering mechanism, and a torque detected by the torque sensor 4. A steering assist electric motor 7 driven and controlled by the control unit 6 based on the control signal, a transmission means 8 for transmitting the rotation of the electric motor 7 to the second steering shaft 3, the transmission means 8 and the torque sensor 4. And a first housing 9 for supporting the steering shafts 1 and 3. The electric motor 7 is attached to the housing 9.

The first steering shaft 1 is formed in a cylindrical shape.
The torsion bar 2 is inserted into a hole of the steering shaft 1,
The upper end of the torsion bar 2 and the upper end of the steering shaft 1 are connected by a dowel pin 10.
The torque sensor 4 is arranged around the.

The second steering shaft 3 has a fitting hole 31 at an upper end and the pinion 5 at a lower end. The lower end of the steering shaft 1 is fitted into the fitting hole 31 so as to be relatively rotatable, and the lower end of the torsion bar 2 is spline-fitted.

The torque sensor 4 is connected to an input section of the control section 6 using a microprocessor, and a motor drive circuit 11 of the electric motor 7 is connected to an output section.
Is connected.

The transmission means 8 is a hypoid gear having a small gear 8a serving as a hypoid pinion and a large gear 8b serving as a hypoid wheel. The small gear 8a is formed integrally with the end of the rotor shaft of the electric motor 7. Have been. The large gear 8b has teeth on one side of the conical portion, and an inner peripheral surface is fitted around the intermediate portion of the steering shaft 3.

The electric motor 7 is connected to the first housing 9.
A bottomed cylindrical second housing 70 which is detachably connected to the housing 7 via a cylindrical adapter 12;
0, a rotor 72 rotatably disposed in the stator 71, a rotor 72,
2, a cylindrical commutator 73 attached to the
A plurality of brushes that come into contact with a peripheral surface of the motor drive circuit 11; and a brush holder that movably accommodates the brushes toward the commutator 73.
The motor drive circuit 11 is connected to a power supply such as a battery and the control unit 6, and a brush holder is mounted in the housing 70.

The second housing 70 has a bottom wall 70a
Of the first fitting portion 1 having a cylindrical shape,
3 are provided. Also, the second part is located at the center of the adapter 12.
Are provided.

The rotor 72 has one end thereof connected to the first bearing 1.
A rotor shaft 72a rotatably supported by the first fitting portion 13 through the first bearing 5 and rotatably supported by the second fitting portion 14 through the second bearing 16 at the other end; The rotor shaft 72a
And a driving winding 72b fixed to an intermediate portion of the commutator 73. The driving winding 72b is connected to the commutator 73.

FIG. 2 is an enlarged sectional view of a bearing portion of the electric motor, and FIG. 3 is an enlarged sectional view taken along line III-III of FIG. The first bearing 15 is provided in an inner ring 15a and an outer ring 15b loosely fitted via a plurality of rolling elements 15c, and in a space 15d between both ends of the inner ring 15a and the outer ring 15b in the axial direction and the rolling elements 15c. And a pair of sealing rings 15e made of rubber. A sealing ring 15 is provided on the inner peripheral surfaces of both ends of the outer ring 15b.
An annular groove 15f for fitting and fixing the outer peripheral portion of e is provided, and a radial step 15g is provided on the outer peripheral surfaces of both ends of the inner ring 15a.

The sealing ring 15e has an outer peripheral portion fitted and fixed in the annular groove 15f, and an inner peripheral portion is arranged so as to face the step portion 15g of the inner ring 15a in a non-contact manner. In addition, lubricant such as grease filled in the space 15d between the outer ring 15b is prevented from flowing out.

In the intermediate portion between the outer peripheral portion and the inner peripheral portion of the sealing ring 15e, the cavities 7a and 7b in the housing 70 facing both ends of the bearing 15 are formed with the cavities 15d between the inner ring 15a and the outer ring 15b. There is provided a communication passage 17 that communicates with each other through the intermediary. The communication path 17 is formed of a relatively small diameter through hole formed in the plate portion, and a plurality of the communication paths 17 are provided at circumferential positions. The number of the communication passages 17 may be one in addition to a plurality.

The assembling of the electric motor configured as described above is performed by the rotor shaft 7 having the other end supported on the first housing 9 side via the second bearing 16 and the second fitting portion 14.
In a state where the first bearing 15 is fitted and fixed to one end of 2a,
The bottomed cylindrical second housing 70 in which the stator 71 is fitted and fixed to the inner peripheral surface is inserted from the first bearing 15 side to the outer periphery of the rotor 72. The outer periphery of one end of the bearing 15 contacts the first fitting portion 13 and the bearing 1
5 is fitted to the fitting portion 13.

When the bearing 15 is fitted, the cavities 7a and 7b in the housing 70 at which both ends of the first bearing 15 face.
Are connected to each other via a communication passage 17 provided in a sealing ring 15e of the bearing 15 and a space 15d between the inner ring 15a and the outer ring 15b, so that the bearing 15 is completely fitted to the fitting portion 13. The air in one of the vacancies 7a in the process up to
7 is sent to the other space 7b, and the air in the one space 7a can be favorably prevented from being pressurized. Accordingly, it is possible to prevent the inner peripheral portion of the sealing ring 15e from contacting the stepped portion 15g of the inner ring 15a due to the pressurized air, and prevent an increase in the rotational resistance of the rotor 72 that rotates integrally with the inner ring 15a. The return of the steered wheels can be kept good.

The cavities 7a and 7b in the housing 70 where both ends of the first bearing 15 face each other are provided on the sealing ring 15e even when the bearing 15 is completely fitted into the fitting portion 13. Since the passage 17 and the space 15d between the inner wheel 15a and the outer wheel 15b communicate with each other, the relative rotation between the inner wheel 15a and the outer wheel 15b and the rolling of the rolling element 15c when the electric motor 7 assists the steering. The temperature of the bearing 15 rises due to the frictional resistance of the bearing 15, and the air in the cavity 7 a thermally expanded by the heat generated by the bearing 15 is transferred to the communication passage 17 and the inner ring 15 a
And the space 15d between the outer ring 15b and the other space 7b. Therefore, the inner peripheral portion of the sealing ring 15e is formed by the stepped portion 15g of the inner ring 15a by the thermally expanded air.
, The rotation resistance of the rotor 72 that rotates integrally with the inner ring 15a can be prevented, and good return of the steered wheels can be maintained.

Second Embodiment FIG. 4 is a longitudinal sectional view of a bearing portion showing the structure of a second embodiment, and FIG. 5 is a sectional view taken along line VV of FIG. In the second embodiment, instead of providing the communication path 17 in the sealing ring 15 e of the bearing 15,
The first fitting portion 13 has a communication passage 17a formed of a groove that is long in the axial direction, and both ends of the communication passage 17a
5 are open to vacancies 7a and 7b in the housing 70 facing both ends.

Since other structures and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals.
The detailed description and the description of the operation will be omitted.

In the above-described embodiment, the communication paths 17, 17a are provided in the sealing ring 15e of the first bearing 15 or the first fitting portion 13 of the housing 70. One end outer peripheral surface to which 72 bearings 15 are fitted;
Inner peripheral surface of the inner ring 15a of the bearing 15, outer peripheral surface of the outer ring 15b,
It may be provided at either the radially intermediate portion of the inner ring 15a or the outer ring 15b.

In the embodiment described above, the electric motor 7 is used for the electric steering device. However, the electric motor 7 may be used for other than the electric steering device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electric steering device according to the present invention.

FIG. 2 is an enlarged sectional view of a bearing portion of the electric motor according to the present invention.

FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 1;

FIG. 4 is a longitudinal sectional view of a bearing portion showing a configuration of an electric motor according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is an enlarged sectional view of a bearing portion of a conventional electric motor.

FIG. 7 is an explanatory view showing a process of assembling a conventional electric motor.

[Explanation of symbols]

 6 Control part 7 Electric motor 70 Housing 71 Stator 72 Rotor 13 Fitting part 15 Bearing 15a Inner ring 15b Outer ring 15c Rolling element 15e Sealing ring 17, 17a Communication passage 7a, 7b Empty space 8 Transmission means

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Claims (3)

[Claims] 1. An electric motor in which a bearing supporting a rotor is fitted in a housing having a fitting portion, wherein the bearing has an inner ring loosely fitted through a plurality of rolling elements. A sealing ring for preventing lubricant from flowing out between the outer rings, wherein at least one of the bearing, the fitting portion, and the rotor is provided;
The electric motor further comprises a communication passage for communicating the cavities facing both ends of the bearing with each other. 2. The electric motor according to claim 1, wherein the sealing ring has the communication path. 3. An electric motor according to claim 1 or 2, a control unit for controlling the driving of the electric motor in accordance with the steering of a steering means, and transmitting a torque of the electric motor to a steering mechanism. An electric steering device comprising: