Motor vehicles – Steering gear – With electric power assist
Reexamination Certificate
1998-04-15
2001-03-13
Hurley, Kevin (Department: 3619)
Motor vehicles
Steering gear
With electric power assist
Reexamination Certificate
active
06199654
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle steering apparatus capable of changing a transmission ratio of the steering angle of a steering wheel to the turning angle of a tire.
2. Related Background Art
A steering apparatus disclosed in Japanese Patent Laid-Open No. 3-153467 is available as a conventional steering apparatus capable of changing the transmission ratio of the steering angle of the steering wheel to the turning angle of the tire. This steering apparatus comprises a transmission ratio change mechanism constituted by a planetary gear differential mechanism mounted on a steering shaft between a steering wheel and a pinion connected to a tire.
The transmission ratio change mechanism of this steering apparatus is of a differential type. For this reason, when an excessive reverse input acts from a vehicle wheel or tire during traveling, this reverse input moves the transmission ratio change mechanism to change the relationship between the steering amount of the steering wheel and the turning amount of the tire.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vehicle steering apparatus capable of maintaining the relationship between the steering amount of a steering wheel and the turning amount of a tire even if an excessive reverse input acts during traveling.
In order to achieve the above object according to the present invention, there is provided a vehicle steering apparatus comprising transmission ratio change means arranged midway along a steering transmission system for connecting a steering wheel and a turned wheel, and control means for variably controlling the transmission ratio change means in accordance with a state of a vehicle,
the transmission ratio change means comprising:
a motor whose rotation is controlled by the control means, and
a reducing mechanism for reducing a rotation speed of the motor,
wherein a housing for the motor and an reduction output terminal of the reducing mechanism are connected to the steering transmission system.
The reducing mechanism desirably has a high reduction ratio enough to decrease a phase shift amount between a steering angle of the steering wheel and a turning angle of the turned wheel with respect to a force reversely input from the turned wheel through the steering transmission system to be less than a predetermined value.
With this arrangement, the apparent motor inertia viewed from the turned wheel side can be increased, and a phase shift amount by an RF reverse input (kick back) can be decreased.
A connection portion for connecting the transmission ratio change means to the steering transmission system preferably comprises a cylindrical yoke fixed to the body of the transmission ratio change means for coupling the transmission ratio change means to the steering transmission system, and holding means for holding a coupled state between the cylindrical yoke and the steering transmission system,
wherein the holding means is detachably mounted on an outer circumferential surface of the cylindrical yoke.
With this arrangement, a wire component for supplying power from a body side to the transmission ratio change means can be disposed on an outer circumferential surface of the cylindrical yoke between the holding means and the body of the transmission ratio change means. The wire component can be made compact, compared to the case wherein the wire component is disposed outside the body of the transmission ratio change means.
The wire component for supplying power from a body side to the transmission ratio change means may be disposed at a column portion supporting a steering shaft of the steering transmission system.
Since the wire component is separated from the transmission ratio change means, the transmission ratio change means can be made compact, and particularly the size in the axis direction can be reduced.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
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patent: 5631511 (1997-05-01), Schulmann et al.
patent: 5925082 (1999-07-01), Shimizu et al.
patent: 3830654 A1 (1989-11-01), None
patent: 0 480 159 A1 (1992-04-01), None
patent: 62-20755 (1987-01-01), None
patent: 3-153467 (1991-07-01), None
Kawamuro Junji
Kojo Takahiro
Matsuda Morihiro
Shindo Masahiko
Hurley Kevin
McKinley Kevin
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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