KR20090079350A - Motor for electric power steering - Google Patents

Abstract

A motor for electric power steering is provided to absorb vibration generated when a rotation axis and a rotor rotate by an elastic member even when the vibration is transmitted to the elastic member through a ball bearing. A motor for an electric power steering includes a housing(110), a bracket(120), first and second ball bearings(131,135), a rotation axis, a rotor(150), a stator(160), and an elastic member. The housing and the bracket are combined with each other. The first and second ball bearings are arranged opposite to one side of the housing and the bracket. One side the rotation axis is supported by the first ball bearing and the other side is supported by the second ball bearing and connected to a steering column of a vehicle. The rotor is combined with the rotation axis and rotates with the rotation axis. The stator is combined with the housing and rotates the rotor. The elastic member is located between the first ball bearing and the housing and applies pre-load to the first ball bearing.

Description

Motor for electric power steering {MOTOR FOR ELECTRIC POWER STEERING}

1A is a cross-sectional view of a conventional motor.

Figure 1b is a perspective view of the elastic member shown in Figure 1a.

2 is a partially cutaway perspective view of a motor according to an embodiment of the present invention.

3 is a perspective view of the elastic member shown in FIG.

Explanation of symbols on the main parts of the drawings

110 housing 120 bracket

131,135: first and second ball bearing 140: rotating shaft

150: rotor 160: stator

190: elastic member

The present invention relates to a motor for electric power steering (hereinafter referred to as "EPS").

The vehicle is provided with an ECU (Electric Control Unit) for receiving electrical signals detected by various input sensors and outputting digital control signals for driving various actuators on the output side. In addition, the EPS motor receives a signal from the ECU to assist the driver's steering force to allow the driver to steer lightly and quickly.

A conventional EPS motor will be described with reference to FIGS. 1A and 1B. Figure 1a is a cross-sectional view of a conventional motor, Figure 1b is a perspective view of the elastic member shown in Figure 1a.

As shown, the housing 11 and the bracket 13 coupled to each other are provided, and the first and second ball bearings 15 and 17 are correspondingly installed on the lower surface and the bracket 13 of the housing 11. .

The first and second ball bearings 15 and 17 are respectively rotatably installed at the lower end side and the upper side of the rotary shaft 21, and a steering shaft (not shown) of the vehicle is connected to the upper end side of the rotary shaft 21. .

The rotor 23 having the yoke 23a and the magnet 23b is fixed to the outer circumferential surface of the rotating shaft 21, and the stator 25 having the core 25a and the coil 25b is fixed to the inner circumferential surface of the housing 11. It is fixed. Thus, when a current is supplied to the coil 25b, the rotating shaft 21 rotates while the rotor 23 rotates by the action of the rotor 23 and the stator 25, thereby rotating the steering shaft. do.

The first and second ball bearings 15 and 17 have an outer racer 15a and 17a, an inner racer 15b and 17b and a plurality of balls 15c and 17c, respectively. At this time, the ring-shaped metal springs 31 bent in the axial direction along the circumferential direction so that the axial positions of the outer racers 15a and 17a and the inner racers 15b and 17b do not change even during the rotation of the rotary shaft 21. ) Is applied between the first bearing 15 and the housing 11 to preload the first ball bearing 15.

In detail, the outer racer 15a of the 1st bearing 15 is supported by the support pipe 11a of the housing 11, and the inner race 15b rotates integrally with the rotating shaft 21. As shown in FIG. At this time, the outer racer 15a has a clearance with the support pipe 11a, and the spring 31 is interposed between the outer racer 15a and the housing 11.

Then, since the axial preload acts on the outer racer 15a by the spring 31, the flow of the ball 15c is prevented even when the rotating shaft 21 rotates, so that noise is reduced and vibration of the rotating shaft 21 is reduced. Decreases.

However, in the conventional motor as described above, since the spring 31 for preloading is formed of metal, the vibration generated when the rotating shaft 21 and the rotor 23 rotate is relatively much made of metal through the spring 31. Is delivered to the housing 11. Due to this, there is a disadvantage that a lot of vibration and noise are generated.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention to provide a motor for EPS that can reduce vibration and noise.

EPS motor according to the present invention for achieving the above object, the housing and the bracket coupled to each other; First and second ball bearings respectively installed to face one surface of the housing and the bracket; One end side is supported by the first ball bearing, the other side is supported by the second ball bearing rotatably installed, the other end side is a rotation shaft connected to the steering shaft side of the vehicle; A rotor coupled to the rotation shaft to rotate integrally with the rotation shaft; A stator coupled to the housing and acting with the rotor to rotate the rotor; It is installed between the first ball bearing and the housing includes an elastic member made of synthetic resin to apply a preload to the first ball bearing.

Hereinafter, an EPS motor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a partially cutaway perspective view of a motor according to an embodiment of the present invention, and FIG. 3 is a perspective view of the elastic member shown in FIG. 2.

As shown, the motor for electric power steering (hereinafter referred to as "EPS") according to the present embodiment has a cylindrical housing 110 of which one side is sealed and the other side of the motor 110 is closed. The other side of the open bracket 120 is coupled.

Hereinafter, in referring to the face and direction of other components including the housing 110, the closed face and direction of the housing 110 are referred to as "lower and lower side", and the open face and direction are referred to as "upper and upper side." .

Support tubes 113 and 123 protrude from the lower surface of the housing 110 and the brackets 120 so as to correspond to each other, and the first and second ball bearings 131 and 135 are respectively supported by the support tubes 113 and 123.

The lower end side and the upper side of the rotation shaft 140 are supported by the first and second bearings 131 and 135 so as to be rotatable. At this time, the upper end side of the rotating shaft 140 is exposed to the upper side of the bracket 120 is connected to the steering shaft (not shown) of the vehicle.

The rotor 150 and the stator 160 are fixed to the outer circumferential surface of the rotating shaft 140 and the inside of the housing 110, respectively.

The rotor 150 has a yoke 151 fixed to the outer circumferential surface of the rotating shaft 140 and a magnet 155 coupled to the yoke 151, and the stator 160 surrounds the magnet 155 to form a housing 110. The core 161 is fixed to the inner circumferential surface of the c) and the coil 165 wound around the core 161 is provided.

Thus, when a current is supplied to the coil 165, the magnet 155 is rotated by the electromagnetic field formed between the magnet 155 and the coil 165, thereby rotating the steering shaft while the rotary shaft 140 rotates. .

In order to drive the EPS motor, the rotation angle of the rotation shaft 140 must be sensed to supply an appropriate current to the coil 165.

In order to detect the rotation angle of the rotating shaft 140, the plate 170, the ring-shaped first and second sensing magnets (173, 175) is installed to the portion of the rotating shaft 140 located above the bracket 120 The printed circuit board (PCB) 180 on which the first and second sensors 183 and 185 are installed is coupled to an upper surface of the bracket 120.

The first and second sensing magnets 173 and 175 have different diameters and different pole numbers, and the first and second sensors 183 and 185 sense magnetic flux changes of the rotating first and second sensing magnets 173 and 175, respectively. It is delivered to the vehicle's ECU (Electric Control Unit).

In detail, when the rotation shaft 140 rotates, the first and second sensing magnets 173 and 175 installed on the plate 170 also rotate integrally with the rotation shaft 140. Then, the magnetic flux changes of the first and second sensing magnets 173 and 175 are sensed by the first and second sensors 183 and 185 and transmitted to the ECU, and the ECU calculates the received signal appropriately to rotate the rotating shaft 140. After calculating the rotation angle of the appropriate current is supplied to the coil 165.

The first and second ball bearings 131 and 135 are positioned inside the outer racers 131a and 135a and the outer racers 131a and 135a to be concentric with the outer racers 131a and 135a, respectively. And a plurality of balls 131c and 135c interposed between the racers 131b and 135b and the outer racers 131a and 135a and the inner racers 131b and 135b, respectively. At this time, the outer racers 131a and 135a and the inner racers 131b and 135b have a play with the balls 131c and 135c, respectively. As a result, when the outer racers 131a and 135a or the inner racers 131b and 135b are rotated, the balls 131c and 135c move between the outer racers 131a and 135a and the inner racers 131b and 135b and make noise. This occurs and the outer racers 131a and 135a or the inner racers 131b and 135b vibrate. To prevent this, preload is applied to the outer racers 131a and 135a or the inner racers 131b and 135b so that the shafts of the outer racers 131a and 135a and the inner racers 131b and 135b are rotated even when the rotating shaft 140 rotates. Do not change the direction position. Then, the balls 131c and 135c do not flow even when the rotating shaft 140 rotates, and the outer racers 131a and 135a or the inner racers 131b and 135b do not vibrate.

The EPS motor according to the present embodiment applies a preload to the first ball bearing 131.

In detail, the outer racer 131a of the first ball bearing 131 is supported by the support tube 113 while having a play with the support tube 113, and the rotation shaft 140 is press-coupled to the inner racer 131b. .

The elastic member 190 made of a synthetic resin that applies preload to the outer racer 131a is interposed between the outer racer 131a of the first ball bearing 131 and the housing 110. That is, since the outer racer 131a of the first ball bearing 131 is installed to be able to move up and down of the support pipe 113, and the inner racer 131b is fixed to the rotation shaft 140, the outer racer 131a is attached to the outer racer 131a. Preload is applied so that the axial positions of the outer racer 131a and the inner racer 131b do not change.

However, since the elastic member 190 according to the present embodiment is formed of a synthetic resin, vibration generated when the rotating shaft 140 and the rotor 150 are rotated is transmitted to the elastic member 190 through the first ball bearing 131. Even if it is, most of the absorbed by the elastic member 190, it is relatively less delivered to the metal housing (110). This relatively reduces vibration and noise.

In addition, irregularities 191 are formed on the upper and lower surfaces of the elastic member 190 in contact with the outer racer 131a of the housing 110 and the first ball bearing 131, respectively, in the axial direction along the circumferential direction. do. Then, since the contact area of the outer racer 131a of the first ball bearing 131 and the elastic member 190 in contact with the housing 110 is small, the vibration transmitted to the housing 110 is less. This further reduces vibration and noise.

The outer circumferential surface of the magnet 155 may be wound around the film to prevent the magnet 155 from being separated.

As described above, in the EPS motor according to the present invention, an elastic member for preloading the ball bearing is formed of a synthetic resin. Therefore, even if the vibration generated during the rotation of the rotating shaft and the rotor is transmitted to the elastic member through the ball bearing, most of the vibration is absorbed by the elastic member and is transmitted less to the housing. This reduces vibration and noise.

In the above, the present invention has been described in accordance with one embodiment of the present invention, but those skilled in the art to which the present invention pertains have been changed and modified without departing from the spirit of the present invention. Of course.

Claims (3)

Mutually coupled housings and brackets; First and second ball bearings respectively installed to face one surface of the housing and the bracket; One end side is supported by the first ball bearing, the other side is supported by the second ball bearing rotatably installed, the other end side is a rotation shaft connected to the steering shaft side of the vehicle; A rotor coupled to the rotation shaft to rotate integrally with the rotation shaft; A stator coupled to the housing and acting with the rotor to rotate the rotor; A motor for electric power steering, which is installed between the first ball bearing and the housing and includes an elastic member made of synthetic resin to apply a preload to the first ball bearing. The method of claim 1, A support tube protrudes from one surface of the housing, The first ball bearing has an outer racer supported by the support tube while having a play with the support tube, an inner racer and an outer racer in which the rotary shaft is press-fitted and coupled to the inner side of the outer racer. And a plurality of balls interposed between the inner spacer and The elastic member is formed in a ring-shaped electric power steering motor installed between the outer racer and the housing. The method of claim 2, At least one of the one surface and the other surface of the elastic member in contact with the housing and the outer racer, respectively, the electric power steering motor is formed in the axial direction along the circumferential direction.

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