Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-09-24
2001-08-07
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S042000, C180S435000
Reexamination Certificate
active
06272409
ABSTRACT:
The present invention relates to steering systems for motor vehicles. More particularly, the present invention relates to a steering control system that permits achievement of virtually perfect Ackerman geometry. A further benefit to be derived from the system is greater freedom of placement of steering system components among other components of a vehicle.
BACKGROUND OF THE INVENTION
Ackerman steering geometry can be explained by examining the relationships of components of a typical two-wheeled steering system situated on the front axle of a motor vehicle. As the vehicle negotiates a turn in a roadway, both the inside and the outside wheels must be turned to correspond to the turn. In doing so, both wheels take two distinct arc-like paths which ideally will have a common center point that is located at the point of intersection of a line extending inwardly from the rotational center of the rear axle of the vehicle and toward the central region of the turn being negotiated and two similar inwardly extending lines, one of which originates at the rotational center of the inside wheel of the front axle and the other of which has its starting point at the rotational center of the outside wheel of the front axle. For correct steering and to avoid undesirable scrubbing of rubber from the tread region of the tire on the outside wheel, the arc-like path taken by that wheel must have that same center point as the arcuate path taken by the inside wheel. However, because the inside and outside wheels are spaced apart from each other on the front axle, i.e., they have what is commonly called a “track width”, the radius of the curved path taken by the outside wheel must be larger than the radius of the path taken by inside wheel. As a consequence, the outside wheel must be turned inwardly at a turning angle that is less than the turning angle provided to the inside wheel. When the center points of inside and outside wheel paths are coincident, a condition known as perfect Ackerman exists. Such a state is desirable in a vehicle dynamics sense, because any deviation from it results in Ackerman error degradation of vehicle handling characteristics.
At the present time, the only means available for controlling Ackerman geometry is generally through the placement of various components of the steering system, and more specifically, through the positioning of the outer tie rod ball joints. Such positioning has often proved to be difficult or impossible, because movement of the outer tie rod ball joints in an outboard direction typically runs into physical constraints within the wheel rims. The present invention facilitates the placement process and helps to better cope with the indicated physical limitations by allowing greater freedom for placement of the tie rod ball joints and other components in a range of locations, which is advantageous for vehicle packaging issues.
SUMMARY OF THE INVENTION
It is therefore an advantage of the present invention to provide a motor vehicle steering box which can be used with light duty trucks and with other vehicles and which is provided with a means for specifically controlling Ackerman geometry regardless of the location of the outside tie rod ball joint and for independently controlling left and right tie rod links. This advantage is provided by a motor vehicle steering box comprising: a function generation means; a first connecting means for linking the function generation means to a steering column and steering wheel of the vehicle steering system; a second connecting means for linking the function generation means to a first tie rod of a linkage apparatus of the steering system; a third connecting means for linking the function generation means to a second tie rod of the linkage apparatus; and a means for ascertaining an angle of rotation of the steering wheel of the steering system when the vehicle makes a turn and for conveying the angle to the function generation means.
This advantage and other novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.
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Dana Corporation
Nguyen Tan
Oldham & Oldham Co. L.P.A.
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