Steering wheel assembly for motor vehicle

Abstract

The invention relates to a steering wheel assembly for a motor vehicle, comprising a steering wheel, a steering angle measuring assembly for measuring the real-time position of the steering wheel, an electrically driven steering wheel heater, and a coil spring box, which contains at least one flat belt cable, the operating current of the electrically driven steering wheel heating part flows through the flat belt type cable, and a current adjusting device for the steering wheel heating part is provided, and the current adjusting device limits the operating current of the electrically driven steering wheel heating part according to the measured steering wheel position.

Description

Technical Field

[0001] The present invention relates to a steering wheel assembly for a motor vehicle, which comprises a steering wheel, a steering angle measuring assembly for measuring the real-time position of the steering wheel, an electrically driven steering wheel heating unit and a coil spring box, wherein the coil spring box comprises at least one flat ribbon cable, and the operating current of the electrically driven steering wheel heating unit flows through the flat ribbon cable. Background Art

[0002] Modern motor vehicles almost without exception have a steering angle measuring assembly, with the aid of which the current position of the steering wheel is electronically detected. The detected steering angle is required, for example, to control an electric power steering. The steering angle measuring assembly comprises an analog steering angle sensor or a digital steering angle sensor, which is arranged on the steering wheel and / or the steering column.

[0003] The signals of the steering angle sensor are usually forwarded via a flat ribbon cable which is arranged in a so-called spring cassette and can be wound or unwound. The spring cassette is often used for the electrical coupling of components of a steering wheel assembly which can be arranged to rotate relative to one another and has at least one stationary housing part (stator) which is connected to the steering column and a housing part (rotor) which can rotate relative thereto and is connected or coupled to the steering wheel.

[0004] An increasingly popular equipment feature of motor vehicles is a device for electrically heating a steering wheel, referred to herein as a steering wheel heater. The operating current for the steering wheel heater is usually also conducted via at least one flat ribbon cable in a spring cassette. In order to achieve comfortable and rapid heating of the steering wheel, a relatively high current intensity must be supplied.

[0005] The electrical power that can be delivered by the spring cassette depends on the position of the flat ribbon cable in the cable chamber. A disadvantageous situation in this regard arises in steering wheel positions in which the flat ribbon cable is completely wound around the rotor or stator of the spring cassette, since the highest electrical power density is generated in the flat ribbon cable. The inevitable ohmic heat generation in the flat ribbon cable is thus concentrated in a small space. The compact arrangement of the flat ribbon cable also results in poor dissipation of the generated heat.

[0006] The situation is significantly better in the position of the steering wheel, in which the flat ribbon cable is evenly distributed on the rotor and stator and also evenly distributed in its space in the spring box. The electrical heat is distributed over a relatively large area, wherein a large part of the surface of the flat ribbon cable is also surrounded by air, and the generated heat can be discharged to the air.

[0007] The exact steering wheel position in which the at least one flat ribbon cable conducting the current for the steering wheel heater is wound up to the maximum extent in the spring cassette depends on the exact arrangement of the flat ribbon cable in the spring cassette. Without limiting the generality, it is assumed that these worst-case scenarios occur in the two most possible steering wheel positions of the steering wheel, which are deflected to the right or to the left.

[0008] The least critical is the central steering wheel position near straight-ahead driving of the motor vehicle, since the flat ribbon cable is positioned loosely in the spring cassette here.

[0009] In order to avoid excessive heating of the flat ribbon cable, the maximum current intensity that can be delivered has been limited to date by the most extreme state of “flat ribbon cable completely wound up.” However, by assuming the limitation of unfavorable conditions, the heating of the steering wheel also lasts longer. Summary of the invention

[0010] An object of the present invention is to provide a steering wheel assembly capable of heating a steering wheel quickly, safely and reliably through a steering wheel heating portion.

[0011] According to the invention, this object is achieved in that a current control device is provided for the steering wheel heater, which current control device limits the operating current of the electrically driven steering wheel heater as a function of the detected steering wheel position.

[0012] Therefore, according to the invention, a steering angle-dependent steering wheel heater current regulation is provided. Based on the steering angle information from the steering angle measuring assembly, the steering wheel heater electronics predetermine a maximum possible current for each steering wheel position.

[0013] The maximum current intensities to be observed for different steering angle positions can be determined empirically in advance, for example on the assumption that predefined limit temperatures are not exceeded in the spring cassette and in particular at the flat ribbon cable carrying the operating current for the steering wheel heater.

[0014] It is particularly advantageous if at least one flat ribbon cable conducting the operating current for the steering wheel heater is arranged in the spring cassette in such a way that it is wound to a minimum in the central position of the steering wheel and to a maximum in the maximum deflected position of the steering wheel, and that the limitation of the operating current for the steering wheel heater is minimum in the straight-ahead position of the steering wheel and maximum in the maximum deflected position of the steering wheel.

[0015] During normal driving operation, the steering wheel is mostly in the vicinity of a central steering wheel position. In these steering wheel positions, at least one flat ribbon cable is wound to the minimum extent, so that the steering wheel heater can be operated at maximum current intensity. In contrast, extreme steering wheel turns, in which the supplied current intensity must be greatly limited, occur relatively rarely. For intermediate steering wheel positions, the supplied current intensity can be adjusted accordingly to an intermediate value.

[0016] In this case, the current intensity depends either in steps or continuously on the steering wheel rotation angle. Electronics are used, which use either the output signal of the steering angle sensor or the correspondingly preprocessed signal or data from the sensor, in order to regulate the current of the steering wheel heater. In this case, the regulating electronics are designed either as an analog circuit or as a digital circuit.

Claims

1. Steering wheel assembly for motor vehicles, It has a steering wheel, Steering angle measurement component for measuring the real-time position of the steering wheel, Electric steering wheel heating unit, and having a coil spring box, the coil spring box including at least one flat ribbon cable, through which the operating current of the electric steering wheel heating unit flows, It is characterized in that A current regulating device is provided for the steering wheel heating unit, and the current regulating device limits the operating current of the electrically driven steering wheel heating unit according to the detected steering wheel position.

2. The steering wheel assembly according to claim 1, characterized in that: The flat ribbon cable is wound in the spring box to the lowest degree in the center position of the steering wheel and to the highest degree in the spring box to the highest degree in the maximum deflection position of the steering wheel, and the limitation on the operating current of the steering wheel heating part is lowest in the straight-ahead position of the steering wheel and highest in the maximum deflection position of the steering wheel.