JP4734883B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering device mounted on an automobile or an industrial vehicle, and more particularly to an improvement for preventing the interference between an electric motor for assisting steering and peripheral components and improving the mountability.

  Electric power steering devices are widely used in automobiles because they can be finely controlled according to driving conditions as compared with hydraulic ones. However, in recent years, as the number of functions of automobiles has increased, the number of parts arranged in the engine room has been increasing, and improvement in mountability of the electric power steering apparatus has been demanded.

  Therefore, as an electric power steering device with improved mountability, Patent Document 1 discloses an electric power steering device in which the axis of an electric motor for assisting steering is arranged substantially parallel to the axis of a rack (steering rod). Yes.

  FIG. 4 is a front view of a steering gear portion of a conventional electric power steering apparatus as disclosed in Patent Document 1, as viewed from the front of the vehicle, and FIG. 5 is a top view thereof. 4 and 5, the electric power steering apparatus 100 includes a pinion shaft 101 linked to the steering wheel and a rack shaft 103 that meshes with the pinion shaft 101 by the steering gear portion 102. The pinion shaft 101 is engaged by the steering gear portion 102. The rotational motion of the shaft 101 is converted into the linear motion of the rack shaft 103. The rack shaft 103 is supported so as to be slidable in the axial direction within the rack casing 104 and steers the wheels via tie rods (not shown) arranged at both ends.

  Further, the rotation of the motor shaft 107 of the electric motor 106 is transmitted to the pinion shaft 101 via the speed reduction mechanism 105. That is, in this electric power steering apparatus 100, the electric motor 106 is driven by ECU current control according to the steering torque and the vehicle speed, and the rotation of the motor shaft 107 of the electric motor 106 is rotated via the speed reduction mechanism 105 to the pinion shaft. By being transmitted to 101, a steering assist force is applied.

  In this electric power steering apparatus 100, as shown in FIGS. 4 and 5, the axis m of the motor shaft 107 and the axis r of the rack shaft 103 are arranged substantially in parallel, whereby the electric motor 106 is mounted on the rack casing 104. And the dust boot 108 are prevented from interfering with each other.

  6 shows an electric power steering apparatus 100 ′ in which the electric motor 106 of the electric power steering apparatus 100 shown in FIG. 4 is arranged so that the axis line p of the pinion shaft and the axis line m of the motor shaft are perpendicular to each other. FIG. As is clear from comparison between FIG. 4 and FIG. 6, the electric power steering apparatus 100 has a height h of the electric motor 106 with respect to the rack casing as a reference to the height of the electric motor 106 in the electric power steering apparatus 100 ′. It is smaller than h ′. In other words, the electric power steering device 100 improves the mountability in the vehicle vertical direction by reducing the space above the electric motor 106 required when mounted on the vehicle.

  Similarly, by giving a degree of freedom to the intersection angle between the axis of the rotating shaft (motor shaft) of the electric motor (electric motor) and the axis of the pinion shaft, and arranging the motor shaft in a direction close to parallel to the rack shaft, Patent Document 2 discloses an electric motor that is compactly mounted.

JP 2000-219140 A Japanese Patent Publication No.3-11941

  However, in Patent Document 1, since the axis m of the motor shaft 107 and the axis r of the rack shaft 103 are arranged substantially in parallel, the electric motor 106 is engaged with the worm wheel in the speed reduction mechanism 105. In the pitch circle shape, it is arranged at a position farthest from the rack shaft 103. Therefore, for example, as shown in FIG. 5, the distance between the electric motor 106 and the peripheral component 109 in the engine room disposed behind the electric motor 106 becomes short, and the electric motor 106 interferes with the peripheral component 109. There was a fear. Therefore, when the electric power steering apparatus 100 is mounted on a vehicle, a large space is required in the front-rear direction of the electric motor 106 to prevent the electric motor 106 from interfering with the peripheral component 109. That is, in order to mount the electric power steering apparatus 100 on a recent vehicle in which many parts are arranged in the engine room, the electric motor 106 is made compact not only in the vehicle vertical direction but also in the vehicle longitudinal direction. It was necessary to install.

  Similarly, the electric power steering device disclosed in Patent Document 2 has not been considered for the mounting property of the electric motor in the vehicle front-rear direction. Therefore, when mounting on a recent vehicle with a large number of parts, There was a restriction on the placement space.

  Therefore, the present invention has been made in view of the above circumstances, and its object is to provide an electric motor that is mounted not only in the vehicle vertical direction but also in the vehicle longitudinal direction when the electric power steering device is mounted on the vehicle. On the other hand, by being arranged so as to be compact, it is possible to prevent interference with peripheral components arranged in the engine room and to improve the vehicle mountability of the electric power steering apparatus.

The object of the present invention is to provide a pinion shaft linked to the steering shaft, a rack shaft for changing the turning angle by converting the rotational motion of the pinion shaft into a linear motion in the longitudinal direction at the steering gear portion, and the steering shaft. An electric motor that rotationally drives the motor shaft according to the generated steering torque, and a speed reduction mechanism that decelerates the rotation of the motor shaft and transmits it to the pinion shaft, and at least the steering gear portion and the electric motor are mounted on the vehicle. Rutotomoni disposed in the engine room, the electric power steering apparatus in which the peripheral part is provided on the vehicle front side of the electric motor, in front view when viewing the steering gear unit from the front, the axis of the motor shaft The crossing angle between the pinion axis and the pinion axis is equal to the crossing angle between the pinion axis and the rack axis. Ri, in the upper view viewed steering gear unit from above, Ri at least a portion of the motor body and Do heavy rack shaft, and so that the space required for the vehicle mounted is minimized, the motor body in the longitudinal direction This is achieved by arranging the electric motor so that the rear end and the rear end of the gear box housing the speed reduction mechanism are substantially in the same position .

  Further, the above object is effective when the crossing angle between the axis of the motor shaft and the axis of the rack shaft is 10 ° to 30 ° in an upper view when the steering gear portion is viewed from above. Achieved.

  As described above, according to the electric power steering apparatus according to the present invention, when the steering gear portion is viewed from the front, the crossing angle between the axis of the motor shaft and the axis of the pinion shaft is the axis of the pinion shaft and the rack shaft. When the vehicle is mounted on the vehicle, the electric motor is arranged so that at least a part of the motor body overlaps the rack shaft when viewed from above when the steering gear is viewed from above. The space can be minimized not only in the vertical direction but also in the front-rear direction. As a result, it is possible to prevent interference of the electric motor with respect to peripheral components arranged in the front-rear direction of the electric motor, and therefore, it is possible to improve mountability on recent vehicles having a large number of components.

  In addition, when the steering gear portion is viewed from above, the crossing angle between the axis of the motor shaft and the axis of the rack shaft is set to 10 ° to 30 °, so that the steering assist motor of the electric power steering apparatus can be used. When a general-sized electric motor is mounted, the motor body can be arranged so as to overlap the rack shaft, and the design flexibility of the electric power steering in the longitudinal direction of the vehicle can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an electric power steering apparatus 1 according to an embodiment of the present invention. In the figure, an electric power steering apparatus 1 includes a pinion shaft 3 linked to a steering shaft 2, and a rack that converts rotational motion of the pinion shaft 3 into linear motion in a longitudinal direction (axial direction) by a steering gear portion 4. When a steering force is applied from a steering wheel 6 composed of a shaft 5 and linked to the steering shaft 2, the rack shaft 5 linearly moves in the axial direction, and the linear motion is transferred from the tie rods 7, 7 to the wheels 8, 8. It is transmitted and the turning angle is changed.

  In addition, the electric power steering apparatus 1 performs steering assistance by transmitting the rotation of the motor shaft 11 of the electric motor 10 to the pinion shaft 3 via the speed reduction mechanism 9. In the electric motor 10, the ECU 14 controls the motor supply current in accordance with signals from various sensors such as a torque sensor 12 that detects a steering torque generated in the steering shaft 2 and a vehicle speed sensor 13 provided in the wheel 8. The drive is controlled.

  FIG. 2 is a front view of the steering gear portion 4 of the electric power steering apparatus 1 as viewed from the front of the vehicle, and FIG. 3 is a top view thereof. 2 and 3, the rack shaft 5 is slidably supported in the rack casing 15 in the axial direction (left and right directions in FIGS. 2 and 3), and the steering gear portion 4 rotates the pinion shaft 3. Is changed to a linear linear motion, and slides in the axial direction. In the speed reduction mechanism 9, a worm 16 provided at the end of the motor shaft 11 meshes with a worm wheel 17 provided coaxially with the pinion shaft 3, and the rotation of the motor shaft 11 is reduced to reduce the pinion. It is transmitted to the shaft 3.

  In the electric power steering 1 according to the present embodiment, as shown in FIG. 2, the electric motor 10 has an intersection angle X between the axis m of the motor shaft 11 and the axis p of the pinion shaft 3 such that the axis r of the rack shaft 5. And the crossing angle Y of the pinion shaft 3 with the axis p. Accordingly, the height h of the electric motor 10 with respect to the rack casing 15 can be minimized, so that the electric motor 10 is arranged in the rack casing 15, the dust booth 18, or the vertical direction of the electric motor 10. Interference with the components in the room can be prevented, and mountability can be improved.

  In the present embodiment, as shown in FIG. 3, the electric motor 10 is rotationally moved along the pitch circle of the worm wheel 17 from the position of the electric motor 106 shown in FIG. 5 and the rack casing 15. As a result, the space required when the vehicle is mounted can be minimized not only in the vertical direction (the vertical direction in FIG. 2) but also in the front-rear direction (the vertical direction in FIG. 3). As a result, for example, in the electric power steering apparatus 100 of FIG. 5, there is a possibility that the electric motor 106 may interfere with the peripheral component 109 installed in the engine room. In the electric power steering apparatus 1 according to the present embodiment, as shown in FIG. 3, the distance between the electric motor 10 and the peripheral component 20 in the engine room installed at the same position as the peripheral component 109 in FIG. Therefore, it is possible to prevent the electric motor 10 from interfering with the peripheral component 20. Therefore, in the electric power steering apparatus 1 according to the present embodiment, not only the mountability in the vehicle vertical direction but also the mountability in the vehicle longitudinal direction can be improved.

  Further, assuming that the electric motor 10 has a size generally adopted as a steering assist motor (for example, as shown in FIG. 3, the motor diameter D is 80 mm and the motor length L is 110 mm), FIG. The crossing angle Z between the axis m of the motor shaft 11 and the axis r of the rack shaft 5 is preferably 10 ° to 30 °. As a result, the space in the front-rear direction of the electric motor 10 required when mounted on the vehicle can be minimized, and the design flexibility of the electric power steering can be improved.

  In the present embodiment, the electric motor 10 is disposed above the rack shaft 5, but the present invention is not limited to this. For example, the same applies to the case where the electric motor 10 is disposed below the rack shaft 5. Has an effect. Moreover, even if the mounting position of the electric motor 10 is changed between the left and right of the pinion shaft 3 and the upper and lower sides of the rack shaft 5 with respect to the electric power steering apparatus 1 according to this embodiment, the same effect is obtained.

  Although the present invention has been specifically described above, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

1 is a schematic configuration diagram of an electric power steering apparatus according to an embodiment of the present invention. It is the front view which looked at the steering gear part of the said electric power steering device from the vehicle front. It is the top view which looked at the steering gear part of the said electric power steering device from the vehicle upper direction. It is the front view which looked at the steering gear part of the conventional electric power steering device from the vehicle front. It is the top view which looked at the steering gear part of the conventional electric power steering device from the vehicle upper direction. FIG. 5 is a front view showing a state in which the electric motor is arranged so that the axis of the pinion shaft and the axis of the motor shaft are perpendicular to each other in the conventional electric power steering apparatus shown in FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 2 Steering shaft 3 Pinion shaft 4 Steering gear part 5 Rack shaft 9 Deceleration mechanism 10 Electric motor 11 Motor shaft 19 Motor body m Motor shaft axis p Pinion shaft axis r Rack shaft axis X Motor shaft Crossing angle between axis and pinion axis Y Crossing angle between rack axis and pinion axis Z Crossing angle between motor axis and rack axis

Claims (2)

According to the pinion shaft linked to the steering shaft, the rack shaft for changing the turning angle by converting the rotational motion of the pinion shaft into a linear motion in the longitudinal direction at the steering gear portion, and the steering torque generated on the steering shaft An electric motor that rotationally drives the motor shaft, and a speed reduction mechanism that decelerates the rotation of the motor shaft and transmits it to the pinion shaft,
And at least the steering gear unit and the electric motor is disposed in an engine compartment of a vehicle Rutotomoni, electric power steering apparatus in which the peripheral part is provided on the vehicle front side of the electric motor,
The electric motor has a crossing angle between the axis of the motor shaft and the axis of the pinion shaft that intersects the axis of the pinion shaft and the axis of the rack shaft when viewed from the front when the steering gear portion is viewed from the front. It equals the angle, the in the upper view viewed steering gear unit from above, at least part of the motor body, the rack shaft and heavy Do Ri, and so that the space required for the vehicle mounted is minimized, longitudinal An electric power steering apparatus , wherein the rear end of the motor body and the rear end of the gear box that houses the speed reduction mechanism are arranged at substantially the same position in the direction.   2. The electric power steering apparatus according to claim 1, wherein the crossing angle between the axis of the motor shaft and the axis of the rack shaft is 10 ° to 30 ° when the steering gear portion is viewed from above.

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