Steering System of a Two-Track Vehicle

Abstract

A steering system of a two-track vehicle has a control rod which is displaceable transverse to the longitudinal axis of the vehicle, and track rods coupled at the two ends of the control rod, which act on steerable wheels of the vehicle such that the wheels are pivoted around the steering axis of rotation by a displacement of the control rod. The control rod is configured divided into two control rod parts each assigned to a wheel and connected to each other via a coupling member which braces the two control rod parts against each other at least temporarily, and at least temporarily enables a relative movement of the two control rod parts in the transverse direction of the vehicle. The coupling member is connected to each of the control rod parts via screw threads. The screw axis of rotation of the screw threads is the longitudinal axis of the control rod. The control rod parts and/or the coupling member are rotatable around the longitudinal axis.

Claims

1. A steering system of a two-track vehicle, comprising: a control rod displaceable transversely with respect to a vehicle longitudinal axis, two ends of the control rod being articulatedly connected with track rods that act on steerable wheels of the vehicle such that a displacement of the control rod pivots the steerable wheels about their steering axis of rotational, wherein the control rod is split into two control rod parts assigned to, in each case, one wheel, and a coupling element by which the two control rod parts are connected to one another, the coupling element at least intermittently supporting the two control rod parts relative to one another and at least intermittently permitting a relative movement of the two control rod parts in a vehicle transverse direction, the coupling element is connected by way of, in each case, one screw thread to the control rod parts, wherein a screw axis of rotation of the screw thread is a longitudinal axis of the control rod, and the two control rod parts and/or the coupling element are rotatable about the longitudinal axis; a steering spindle, which is connected to a steering wheel for a driver of the two-track vehicle, meshes with the coupling element such that a rotation of the steering spindle causes a displacement of the coupling element in the vehicle transverse direction.

2. The steering system according to claim 1, wherein for at least a partial decoupling between the coupling element and the two control rod parts, which at least partial decoupling permits relative movement between the two control rod parts, a clutch element is provided, the clutch element being actuatable via an actuator.

3. The steering system according to claim 1, wherein each control rod part is assigned a dedicated motor for adjustment thereof.

4. The steering system according to claim 3, wherein the dedicated motor is an electric motor.

5. The steering system according to claim 4, wherein each dedicated motor acts via a ball screw on an associated one of the two control rod parts for displacement thereof.

6. The steering system according to claim 3, wherein each dedicated motor acts via a ball screw on an associated one of the two control rod parts for displacement thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a highly schematic diagram of a steering system having a control rod according to an embodiment of the invention, wherein FIG. 1 is a view in a direction perpendicular to a roadway on which the vehicle is standing.

[0015] FIG. 2 is a highly schematic diagram of FIG. 1 in which parts of the control rod are illustrated in cross-section.

DETAILED DESCRIPTION OF THE DRAWINGS

[0016] Merely one of several possible exemplary embodiments is illustrated in substantially abstracted form in the appended diagrammatic sketches (FIG. 1 shows a view with a viewing direction perpendicular to the roadway on which the vehicle is standing; FIG. 2 illustrates the control rod parts in section), and will be discussed below in addition to the description above.

[0017] The reference designation 1 denotes, as a whole, a control rod which is displaceable transversely with respect to the longitudinal axis L of a two-track vehicle (for example a passenger motor vehicle). The control rod 1 is composed of substantially three individual parts, specifically a first control rod part 1a, situated on the left in the illustration in the figure, a second control rod part 1b, situated on the right in the illustration in the figure, and a coupling element 1c, which connects the two control rod parts 1a, 1b to one another. Here, of the two control rod parts 1a, 1b, in each case only one section, which overlaps the coupling element 1c, is illustrated, and each control rod part 1a, 1b extends further away from the coupling element 1c to the right and to the left. Both the coupling element 1c and the two control rod parts 1a, 1b are of substantially circular cylindrical form and have a common cylinder axis or longitudinal axis A (or axis of rotation A) extending in a vehicle transverse direction Q.

[0018] Each of the mutually averted ends of the control rod parts 1a and 1b, that is to say the left-hand end, not shown in the figure, of the (left-hand) control rod part 1a and the right-hand end, not shown in the figure, of the (right-hand) control rod part 1b is connected by way of a steering-knuckle arm or the like, in a manner known to a person skilled in the art, via a track rod or the like to a steerable wheel (likewise not shown here) of the vehicle, in such a way that a displacement of the respective control rod part 1a or 1b in the vehicle transverse direction Q effects a pivoting of the respective wheel about the steering axis of rotation thereof (also referred to as spreading axis).

[0019] Those end sections of the control rod parts 1a, 1b which face toward the coupling element 1c are in the form of a sleeve with a circular-ring-shaped cylindrical cross section, into the respective inner wall of which there is formed a screw thread G. By way of said screw thread G. Each control rod part 1a, 1b is supported on the coupling element 1c by virtue of the coupling element 1c having, on the outside of its end sections Ca, Cb at both sides, a counterpart screw thread G, and partially projecting by way of said end sections Ca, Cb, or being screwed by way of the screw thread G, into the respective sleeve-shaped end section of the respective control rod part 1a, 1b. The screw thread G in the end section Ca of the coupling element 1c meshes with the corresponding screw thread section G of the control rod part 1a, which surrounds the end section Ca of the coupling element 1c at least in sections in sleeve-like fashion. Analogously, the screw thread G in the end section Cb of the coupling element 1c meshes with the corresponding screw thread section G of the control rod part 1b, which surrounds the end section Cb of the coupling element 1c at least in sections in sleeve-like fashion.

[0020] A further suitably designed thread D is formed on the outer wall of the coupling element 1c in the central section thereof, with which thread D there meshes a pinion (not illustrated in the figures) which is connected by way of a steering spindle (not shown) to a steering wheel (not shown) for the driver of the vehicle. By rotating the steering wheel, the driver can thus, in the conventional manner, displace the control rod 1 in the vehicle transverse direction Q and thus steer the wheels by virtue of, in the present case, the two control rod parts 1a, 1b being displaced in the same direction by way of the coupling element 1c which is displaced (laterally) in the vehicle transverse direction Q by way of the pinion.

[0021] In the present case, each control rod part 1a, 1b is assigned a dedicated control motor 2a and 2b, respectively, in the form of electric motor. Each control motor 2a and 2b is connected to the associated control rod part 1a and 1b, respectively, by way of a ball screw 3, which is illustrated merely symbolically and thus not in any more detail. The outer side of each control rod part 1a, 1b is consequently designed such that the ball screw 3 that is set in motion by the respective control motor 2a and 2b displaces the respective control rod part 1a and 1b correspondingly in the vehicle transverse direction Q.

[0022] When the driver steers using the steering wheel and thus seeks to displace the coupling element in the transverse direction Q, and the two control motors 2a, 2b are suitably actuated by an electronic control unit which identifies the steering demand of the driver, it is initially possible for both control motors 2a, 2b to assist an equal displacement of the two control rod parts 1a, 1b by way of their torque. With equal dimensioning at each control rod part 1a, 1b, it is then the case that the two identical control motors 2a, 2b rotate at the same rotational speed, and each of the control motors 2a, 2b introduces half of the required assistance torque into the steering system. Alternatively, it is however also possible for the two control motors 2a, 2b, with identical dimensioning, to also rotate at different rotational speeds as described above, whereupon the two control rod parts 1a, 1b are displaced differently in the vehicle transverse direction Q. With suitable actuation of the control motors 2a, 2b, it is thus possible to maintain the Ackermann relationship for all steer angles of the vehicle. In the event of a failure of one control motor (2a, 2b), it is ultimately necessary, by way of suitable configuration of the ball screw 3 in conjunction with the screw threads G in the sections Ca, Cb, to ensure that at least a certain assistance torque can be introduced by way of a single control motor 1a or 1b, and both wheels can be steered in the conventional manner by the driver via the coupling element 1c. Furthermore, corresponding steering of the two vehicle wheels by way of the control motors 2a, 2b alone, without a displacement of the coupling element 1c by the driver, is also possible.

[0023] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.