EP-4739546-A1 - COIL SPRING CASSETTE

EP4739546A1EP 4739546 A1EP4739546 A1EP 4739546A1EP-4739546-A1

Abstract

The invention relates to a coil spring cassette comprising a stationary stator housing part and a rotatable rotor housing part, between which a coil gap is formed in which a flexible flat cable that has electric conductors and a flexible ribbon cable are arranged in such a manner that the flat cable and the ribbon cable are wound in opposite directions such that a respective first section of the flat cable and the ribbon cable rests against the inner lateral surface of the stator housing part and a respective second section rests against the outer lateral surface of the rotor housing part such that a U-shaped turning section which reverses the winding direction is formed between the two respective sections of the flat cable and the ribbon cable. The invention is characterized in that the ribbon cable is designed as a thin steel strip, and a permanent magnet is installed in the region of the outer lateral surface of the rotor housing part such that the permanent magnet exerts an attractive effect on the ribbon cable section resting thereon.

Inventors

MOLDENHAUER, KNUT
HESS, CHRISTIAN
PRIEBE, RENE

Assignees

KOSTAL Automobil Elektrik GmbH & Co. KG

Dates

Publication Date: 20260513
Application Date: 20240702

Claims (1)

1 . A coil spring cassette with a fixed, at least partially cylindrical stator housing part (1) and a cylindrical rotor housing part (2) arranged coaxially to the latter and rotatable about its longitudinal axis, wherein a winding gap (5) is formed which is delimited by the inner surface (3) of the cylindrical portion of the outer stator housing part (1) and the outer surface (4) of the inner rotor housing part (2), in which at least one flexible flat cable (6) having an electrical conductor and at least one flexible flat strip (7) serving to mechanically stabilize the flat cable (6) are arranged in such a way that their respective first ends are fastened to the stator housing part (1) and their respective second ends to the rotor housing part (2), and that they are wound in the opposite direction with a respective first section of their length on the inner surface (3) of the stator housing part (1) and with a respective second section of their length on the outer surface (4) of the rotor housing part (2), so that between the two sections of the flat cable (6) and the flat strip (7) a U-shaped turning section (6', 7') reversing the winding direction is formed, characterized in that the at least one flat strip (7) is designed as a thin steel strip, and that in the area of the outer surface (4) of the rotor housing part (2) at least one permanent magnet (8) is mounted in such a way that it exerts an attractive effect on the second section of the length of the flat strip (7) lying there.

Description

winding spring cassette The invention relates to a coil spring cassette with a fixed, at least partially cylindrical stator housing part and a cylindrical rotor housing part arranged coaxially to the latter and rotatable about its longitudinal axis, wherein a winding gap is formed which is delimited by the inner surface of the cylindrical portion of the outer stator housing part and the outer surface of the inner rotor housing part, in which at least one flexible flat cable having an electrical conductor and at least one flexible flat band serving to mechanically stabilize the flat cable are arranged in such a way that their respective first ends are fastened to the stator housing part and their respective second ends to the rotor housing part, and that they are wound in opposite directions with a first section of their length on the inner surface of the stator housing part and with a second section of their length on the outer surface of the rotor housing part, so that a U-shaped turning section reversing the winding direction is formed between the two sections of the flat cable and the flat band. Such coil spring cassettes are designed, for example, to safely transmit energy and/or data in motor vehicles between connection points that are rotatably mounted in the steering wheel and those that are fixed in the area of the steering column. The connection points of such a device can be used to supply an airbag system, a steering wheel heater, a switching device, etc. with the voltage and signals required for their function. EP 0 556 779 B1 has disclosed such a coil spring cassette in which several flexible flat cables are accommodated within a ring-shaped cavity of a housing. One end of each flexible flat cable is fixed to the stator part and the other end of the flexible flat cable is fixed to a rotor part of the housing that can rotate relative to the stator part. The flexible flat cables can be wound with their two broad sides via a U-shaped turning section with at least one turn onto the axially aligned inner wall and, at a distance from this, conversely with at least one further turn onto the axially aligned outer wall of the housing. If a plurality of flat cables is required to provide the necessary electrical connections, this plurality of Flat cables are arranged in such a way that their respective end sections overlap on the outer surface of the inner housing part and on the inner surface of the outer housing part, and the U-shaped turning sections of each of the flat cables generate an elastic compressive force which ensures that the inside or outside wound areas of the other flat cables are securely attached to the housing surfaces. If a smaller number of flat cables is required to provide the necessary electrical connections than is required to ensure the perfect mechanical function of the clock spring cassette, so-called dummy cables are used instead of additional flat cables. These are elastic flat strips that have the same mechanical properties as the flat cables, but unlike the flat cables, they do not contain any electrical conductors. Plastic strips, e.g. made of PET, are used as dummy cables as standard. In practical use, the use of at least four or five cables or dummy cables has proven to be advantageous in order to ensure the perfect mechanical function of the clock spring cassette. These four or five cables or dummy cables must be arranged in such a way that their U-shaped turning sections, which reverse the winding direction, are distributed as evenly as possible over the circumference of the winding gap. In steering systems based on the so-called steer-by-wire principle, where there is no longer a mechanical steering spindle, the steering wheel no longer has to be able to rotate several revolutions. In fact, it usually only needs to be able to rotate by less than 360 degrees, which means that the clock spring cassette no longer has to cover the entire steering spindle. The housing of the clock spring cassette no longer has to be completely ring-shaped in cross-section. It is sufficient if the housing only forms a segment of a ring, which creates additional installation space in this area compared to the state of the art. If several flat cables are required, these must then be arranged much closer together, so that the previously described mechanical stabilization by the U-shaped turning sections of the flat cables evenly distributed over the circumference is no longer possible. It is apparent that, particularly near the connection of the flat cables to the inner rotor housing part, the flat cables are no longer securely attached to the outer surface of this rotor housing part. Therefore, another form of mechanical stabilization is required here, which the clock spring cassette according to the present invention provides in a simple and robust manner. This is achieved according to the invention in that the at least one flat strip is designed as a thin steel strip and in that at leas