Land vehicles – Wheeled – Running gear
Reexamination Certificate
2001-10-19
2003-04-01
Morris, Lesley D. (Department: 3611)
Land vehicles
Wheeled
Running gear
C280S778000
Reexamination Certificate
active
06540243
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2000-320649 filed in Japan on Oct. 20, 2000, the entirety of which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a front wheel steering system for automotive three- and four-wheeled vehicles for steering right and left front wheels.
2. Description of the Background Art
Automotive three-wheeled vehicles or four-wheeled vehicles have a front wheel steering system in which the proportion of the steered angle of the front wheel is variable with respect to the steering angle of the steering handle. One of the known front wheel steering systems of this type is, for example, presented in Japanese Unexamined Patent Application Publication No. 0115442/1994 (hereinafter referred to as a background art), and entitled “RUDDER ANGLE RATIO VARYING APPARATUS”.
Referring to
FIGS. 1 and 2
of the above reference, the background art is constructed in such a manner that by steering the steering wheel
4
(the reference numbers cited herein correspond to those in the above reference), the steering force is transmitted to the steered wheel
30
through the steering shaft
3
, the ball screw mechanism
12
, the conversion nut member
7
, the arm
17
, the lever member
16
, the cylindrical portion
19
, the shaft portion
18
, the first gear
21
, the second gear
26
, the pinion
27
, the rack gear
29
, the rack shaft
28
, the tie rod, and the knuckle arm to rotate the steered wheel
30
.
In the background art described above, as shown in
FIGS. 4 and 9
, the first gear
21
and the second gear
26
are elliptic gears. The steering angle ratio varying means comprises first and second gears
21
,
26
having a non-linear steering angle ratio in which the steered angle of the steered wheel
30
is small in the region where the steering angle of the steering wheel
4
is small. The steered angle increases with the steering angle.
In the background art described above, the first and second gears
21
,
26
constituting steering angle ratio varying means are elliptic gears having a complex configuration, which may increase the cost. In addition, in order to ensure a further stable operation of the steering angle ratio varying means, preferably, the steering angle ratio varying means is stored in a case
1
. The case
1
is utilized to ensure that the input and output portions of the steering angle ratio varying means is properly sealed. Accordingly, the employment of the elliptic gear in the background art may cause an increase in the cost of the steering angle ratio varying apparatus.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to simplify the construction of a steering angle ratio varying means in order to decrease the cost of a front wheel steering system for automotive three- and four-wheeled vehicles.
In order to achieve the object described above, according to a first aspect of the present invention a front wheel steering system for automotive three- and four-wheeled vehicles has right and left front wheels controlled by a steering shaft rotatably mounted on the head pipe of the vehicle body frame. The steering stem is disposed below the steering shaft at a location offset from the steering shaft. The steering stem is connected to the steering shaft via a link mechanism. The right and left front wheels are connected to the steering stem via the right and left tie rods and the right and left knuckle arms. The link mechanism is constructed from an upper link, a lower link, and a universal coupling for coupling the upper link and the lower link. Accordingly, so the steering shaft is disposed between the steering stem and the universal coupling when the link mechanism is viewed in the axial direction of the steering shaft.
When the link mechanism is viewed in the axial direction of the steering shaft, when the steering angle of the steering shaft is zero, the center of the steering shaft, the universal coupling, and the center of the steering stem are aligned. When viewed from the side of the vehicle body in a direction at a right angle with this line, the proportion of the distance from the universal coupling to the center of the steering stem with respect to the distance from the center of the steering shaft to the universal coupling varies in accordance with the steering angle of the steering shaft. Consequently, the proportion of the steered angle of the front wheel with respect to the steering angle of the steering shaft (steering angle ratio) varies in accordance with the steering angle of the steering shaft. In this way, the link mechanism functions to vary the steering angle ratio. This is referred to as a steering angle ratio varying function. Since the mechanism performing the steering angle ratio varying action is a link mechanism, an extremely simple construction may be achieved.
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.
REFERENCES:
patent: 1418679 (1922-06-01), Schipper
patent: 2638356 (1953-05-01), Butterfield et al.
patent: 3768825 (1973-10-01), Magnusson
patent: 3866946 (1975-02-01), Robison
patent: 4749205 (1988-06-01), Takahashi et al.
patent: 6349966 (2002-02-01), Hutter et al.
patent: 37 28 593 (1989-03-01), None
patent: 2 491 650 (1982-04-01), None
patent: 6-115442 (1994-04-01), None
Patent Abstracts of Japan for JP 2000-309280, vol. 2000, No. 14, Mar. 5, 2001.
Furuta Shinji
Kobayashi Hiroyoshi
Ozeki Takashi
Takayanagi Shinji
Birch & Stewart Kolasch & Birch, LLP
Honda Giken Kogyo Kabushiki Kaisha
Lum L.
Morris Lesley D.
LandOfFree
Front wheel steering system for automotive three- and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Front wheel steering system for automotive three- and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Front wheel steering system for automotive three- and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3101680