JP2578758Y2 - Electric power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to downsizing of a power assist section of an electric power steering apparatus.

[0002]

2. Description of the Related Art As a power steering device for steering an automobile, an outboard motor, and the like, an electric power steering device that includes an electric motor and transmits power of the electric motor to a rack shaft by a transmission means to perform power assist has been known. Have been. 2 and 3 show a conventional electric power steering apparatus for a vehicle in this system. Here, the rotation of the steering wheel 1 is
The power is transmitted to a steering rack shaft 4 via a steering pinion 3 provided at the tip of an input shaft 2 linked to the steering wheel 1. That is, the steering wheel 1
Is rotated, the pinion 3 rotates in conjunction with the rotation. The pinion 3 is a rack 6 formed on a rack shaft 4.
The rotational force of the pinion 3 is transmitted to the rack shaft 4. Then, the rack shaft 4 moves in the left-right direction in the figure, and the wheel 5 is steered by the movement of the rack shaft 4.

The rack shaft 4 passes through the inside of a rotor 8 of an electric motor m provided in a housing 7 as shown in FIG. The rotor 8 is rotatably supported by the housing 7 by bearings 9 and 10, and a gear 11 is provided at one end thereof. A ball screw 12 is provided in the housing 7 in parallel with the rack shaft 4. The ball screw 12 is rotatably supported on the housing 7 by bearings 14 and 15 with the screw portion 13 being parallel to the rack shaft 4. A gear 16 is provided at one axial end of the screw portion 13, that is, at the side of the electric motor m, and the gear 16 and the gear 1 of the rotor 8 are provided.
1 is engaged. In addition, ball screw 1
The second nut 17 is fixed to the rack shaft 4 at a position parallel to the screw portion 13. As described above, since the electric motor m and the rack shaft are linked by the ball screw 12, when the electric motor m rotates, the gear 11 provided at one end of the rotor 8 rotates and meshes with the gear 11. The screw portion 13 is also rotated by the gear 16. When the screw portion 13 rotates, the nut 17 moves in the axial direction of the screw portion 13 in accordance with the rotation amount of the screw portion 13, so that the rack shaft 4 fixing the nut 17 also moves the nut 17 Move as much as.

Further, a steering force sensor 18 is provided on the pinion 3 side, and a detection signal of the steering force sensor 18 is sent to the controller C. The controller C drives and controls the electric motor m according to a detection signal from the steering force sensor 18 and a detection signal from the vehicle speed sensor 19. Reference numeral 20 denotes a pressure pad mechanism including a pressure pad 21, a spring 22, and a cover 23, which adjusts the backlash of the engagement between the pinion 3 and the rack 6. Reference numerals 24 and 25 are a magnet and a brush of the electric motor m, respectively.

[0005]

As described above, in the conventional electric power steering apparatus, the housing 7 is used as means for transmitting the driving force of the electric motor m to the rack shaft 4.
The screw portion 13 of the ball screw 12 is provided separately in parallel with the rack shaft 4. For this reason,
The housing 7 becomes large by the size of the ball screw 12, and there is a problem that it cannot be incorporated when housed in a narrow engine room. An object of the present invention is to provide a power steering device which does not require a large storage space by making the housing 7 compact.

In order to solve the above-mentioned problems, according to the present invention, an electric motor is provided in a housing, a rack shaft is passed inside the rotor of the electric motor, and the rack shaft and the electric motor are linked by a transmission means. In an electric power steering device in which a shaft is moved by an electric motor, the transmitting means is an arm provided on a rotor of the electric motor.
Formed on the screw thread and rack shaft and above
A worm that engages with the acme screw
Is located on the inner circumference of the rotor of the electric motor.
I do .

[0007]

The worm formed on the rack shaft passing through the inside of the rotor meshes with the acme screw portion provided on the rotor. If the electric motor is rotated, the acme screw rotates with the rotor, and the worm meshes with the acme screw. Moves in its axial direction. As described above, since the transmission means for moving the rack shaft by the electric motor is provided on the rack shaft and the periphery thereof, the housing can be made compact.

[0008]

FIG. 1 shows an embodiment of the present invention. The same reference numerals are used for the same components as those in the above-described conventional example, and the detailed description is omitted. Here, the electric motor m is mounted in the housing 7 as in the conventional example. An acme screw portion 26 is formed inside the rotor 8 of the electric motor m, and both ends thereof are rotatably supported by the housing 7 by bearings 27 and 28. The rack shaft 4 passes through the inside of the acme screw portion 26, and a worm 29 that meshes with the acme screw portion 26 is formed on the rack shaft 4. By engaging the worm 29 with the acme screw 26, the rotation of the acme screw 26 is converted into the movement of the rack shaft 4 in the axial direction. In the figure, a flat portion 30 is formed on the rack shaft 4 below the rack 6, and a detent mechanism 35 composed of a roller 31, a spring 32, a roller housing 33, and an adjust cover 34 is pressed against the flat portion 30. I have. The rotation preventing mechanism 35 has a role of suppressing rotation of the rack shaft 4 and adjusting a backlash between the pinion 3 and the rack 6.

The electric power steering apparatus constructed as above operates as follows. That is, the rotation from the steering wheel is transmitted to the pinion 3 attached to the tip via an input shaft (not shown). The steering force sensor 18 detects the rotational force of the pinion 3 and
Send it to controller C. The controller C controls the driving of the electric motor m based on the detection signal and information from the vehicle speed sensor 19.

When the electric motor m driven and controlled by the controller C rotates, the acme screw 26 provided inside the rotor 8 also rotates. Acme screw part 26
Engages with the worm 29 formed on the rack shaft 4 and is prevented from rotating by the rotation preventing mechanism 35. Therefore, when the acme screw portion 26 rotates, the rack shaft 4
Moves in its axial direction. When the rack shaft 4 moves in the axial direction, a tire attached to both ends thereof via knuckle arms (not shown) is steered.

The rack shaft 4 is moved by the driving force of the electric motor m driven and controlled by the controller C as described above. As a means for transmitting the driving force of the electric motor m to the rack shaft 4, as described above, Acme screw part 26
And the worm 29. The acme screw portion 26 is provided inside the rotor 8 of the electric motor m, and the rack shaft 4 forming the worm 29 that meshes with the acme screw portion 26 passes through the acme screw portion 26. That is, the acme screw portion 26 that transmits the rotation of the electric motor m to the rack shaft 4 around the rack shaft 4 and the same axis.
And the transmission means including the worm 29,
The housing 7 is more compact than the transmission means using the ball screw 12 as in the conventional example.

That is, in the conventional example, the rack shaft 4
The ball screw 12 is provided in the housing 7 in parallel with the above, and the driving force of the electric motor m is transmitted to the rack shaft 4 by the ball screw 12, so that the size of the housing 7 increases accordingly. However, in this embodiment, since the transmission means including the rack shaft 4 and the acme screw portion 26 and the worm 29 provided coaxially around the rack shaft 4 is used instead of the ball screw 12, the housing 7 can be made compact. . If the housing 7 is compact, a large storage space is not required when storing it in a small engine room. Even if the storage space is very small, the housing 7 is compact, so that it is not impossible to incorporate the housing 7.

[0013]

Since the transmission means for moving the rack shaft by the electric motor is provided on the rack shaft and the periphery thereof, the housing can be made more compact than conventional transmission means using a ball screw, for example. it can. Also, the part provided with the transmission means must be
Ring swells in the radial direction. So, with this idea
Is transmitted in order to reduce the swelling area as much as possible.
The acme screw part that constitutes the means is connected to the rotor of the electric motor.
It is provided on the inner circumference. In this way, it expands in the radial direction
The range can be shortened in the axial direction. Therefore,
The housing can be made compact. That's all
As described above , if the housing is made compact, there is no need to require a large space when storing it in a small engine room, or to prevent the storage space from being too small to be incorporated .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of a conventional electric power steering device.

FIG. 3 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 4 Rack shaft 7 Housing 8 Rotor 26 Acme screw part 29 Worm m Electric motor

Claims (1)

(57) [Scope of request for utility model registration] 1. An electric power steering apparatus in which an electric motor is provided in a housing, a rack shaft is passed through a rotor of the electric motor, and the rack shaft and the electric motor are linked by a transmission means, and the rack shaft is moved by the electric motor. , The transmission means is a rotor of an electric motor.
Acme screw part provided on the rack shaft
Both have a worm that meshes with the acme screw part,
The acme screw is located on the inner circumference of the rotor of the electric motor.
And an electric power steering device.