US 7,308,964 B2 · Vehicle steering apparatus

Abstract

A vehicle steering apparatus includes a steering input section having at least a steering wheel to which steering input is applied, and a steering output section having at least a steering rack shaft and operatively associated with left and right steered wheels for steering the steered wheels by steering-rack-shaft movement produced by a steering force determined based on the steering input and transmitted directly or indirectly to the steering rack shaft. The steering rack shaft is split into left and right movable rack shaft portions. Also provided is a steer angle converter enabling a differential rack stroke between left and right rack strokes of the left and right movable rack shaft portions. The steer angle converter is constructed by at least one of a variable-pitch dual rack arrangement and a dual taper-pulley arrangement of a cable back-up mechanism.

Claims32

Dependent claims

A vehicle steering apparatus comprising:

a steering input section having at least a steering wheel to which steering input is applied;
a steering output section having at least a steering rack shaft and operatively associated with left and right steered wheels for steering the steered wheels by steering-rack-shaft movement produced by a steering force determined based on the steering input;
mechanical transmission means via which the steering force is transmitted to the steering rack shaft;
the steering rack shaft being split into left and right movable rack shaft portions;
and
the mechanical transmission means including a steer angle converter enabling a differential rack stroke between left and right rack strokes of the left and right movable rack shaft portions by one rotation input that is input directly to the steering rack shaft, when steering the left and right steered wheels.

3 more elements

A vehicle steering apparatus comprising:

a steering input section having at least a steering wheel to which steering input is applied;
a steering output section having at least a steering rack shaft and operatively associated with left and right steered wheels for steering the steered wheels by steering-rack-shaft movement produced by a steering force determined based on the steering input and transmitted directly or indirectly to the steering rack shaft;
the steering rack shaft being split into left and right movable rack shaft portions;
and
a steer angle converter enabling a differential rack stroke between left and right rack strokes of the left and right movable rack shaft portions,
wherein:
the steer angle converter comprises:
(i) a left variable-pitch rack-and-pinion mechanism including a left variable rack having a left variable-pitch rack gear portion formed on the left movable rack shaft portion and a left pinion shaft having a left pinion gear portion in meshed-engagement with the left variable-pitch rack gear portion;
and
(ii) a right variable-pitch rack-and-pinion mechanism including a right variable rack having a right variable-pitch rack gear portion formed on the right movable rack shaft portion and a right pinion shaft having a right pinion gear portion in meshed-engagement with the right variable-pitch rack gear portion,
wherein the left and right variable-pitch rack-and-pinion mechanisms cooperate with each other to enable a rack-stroke difference between the left and right movable rack shaft portions for a same pinion-shaft rotary motion;
a steer-by-wire (SBW) system in which the steering wheel of the steering input section is mechanically separated from the steering rack shaft of the steering output section and the steering-rack-shaft movement is produced responsively to a command signal determined based on the steering input;
and
a mechanical back-up system capable of mechanically coupling the steering input section with the steering output section, the mechanical back-up system comprising:
(i) a cable back-up mechanism having three cylindrical pulleys;
and
(ii) a clutch device provided on a side of the steering input section;
and
the SBW system comprising two steering actuators that drive the respective movable rack shaft portions responsively to the command signal.

16 more elements

A vehicle steering apparatus comprising:

a steering input section having at least a steering wheel to which steering input is applied;
a steering output section having at least a steering rack shaft and operatively associated with left and right steered wheels for steering the steered wheels by steering-rack-shaft movement produced by a steering force determined based on the steering input and transmitted directly or indirectly to the steering rack shaft;
the steering rack shaft being split into left and right movable rack shaft portions;
and
a steer angle converter enabling a differential rack stroke between left and right rack strokes of the left and right movable rack shaft portions,
wherein:
the steer angle converter comprises:
(i) a left frusto-conical taper pulley of a cable steering column system associated with a left rack-and-pinion mechanism and fixedly connected to and coaxially arranged with a left pinion shaft, so that an effective diameter of a cable wound on the left taper pulley varies depending on the rack stroke of the left movable rack shaft portion;
and
(ii) a right frusto-conical taper pulley of the cable steering column system associated with a right rack-and-pinion mechanism and fixedly connected to and coaxially arranged with a right pinion shaft, so that an effective diameter of a cable wound on the right taper pulley varies depending on the rack stroke of the right movable rack shaft portion, and that a sum of the effective diameter of the cable wound on the left taper pulley and the effective diameter of the cable wound on the right taper pulley is constant;
wherein the left and right taper pulleys cooperate with each other to provide a differential movement of the left and right pinion shafts and consequently to enable the differential rack stroke between the left and right movable rack shaft portions.

8 more elements

Dependencies are inferred from the claim text.

Vehicle steering apparatus

Life of this patent

Vehicle steering apparatus

Life of this patent

Abstract

Claims32