US-20260128561-A1 - COIL SPRING CASSETTE

US20260128561A1US 20260128561 A1US20260128561 A1US 20260128561A1US-20260128561-A1

Abstract

A coil spring cassette includes a stator housing part and a rotor housing part, between which a winding gap is formed. A flexible flat cable having an electrical conductor and a flexible flat ribbon are arranged in the winding gap and are wound in opposite directions so that a respective first section of the cable and ribbon rests against an inner surface of the stator housing part and a respective second section rests against an outer surface of the rotor housing part with a U-shaped turning section which reverses the winding direction is formed in each case between the two respective sections of the cable and the ribbon. The ribbon is a thin steel strip, and a permanent magnet is mounted in the region of the outer surface of the rotor housing part such that the permanent magnet exerts an attractive effect on the ribbon section resting thereon.

Inventors

Knut Moldenhauer
Christian Hess
Renè Priebe

Assignees

KOSTAL AUTOMOBIL ELEKTRIK GMBH & CO. KG

Dates

Publication Date: 20260507
Application Date: 20260102
Priority Date: 20230704

Claims (1)

1 . A coil spring cassette comprising: a partially cylindrical stator housing part, the stator housing part being partially cylindrical in that the stator housing part includes a cylindrical housing part portion and a non-cylindrical housing part portion; a cylindrical rotor housing part; the rotor housing part is situated coaxially with respect to the stator housing part and the rotor housing part is rotatable relative to the stator housing part; a winding gap between by an inner surface of the cylindrical housing part portion of the stator housing part and an outer surface of the rotor housing part; a flexible flat cable having at least one electrical conductor; a flexible flat ribbon used for mechanical stabilization of the flat cable; the flat cable and the flat ribbon are arranged in the winding gap in such a way that their respective first ends are fastened to the stator housing part and their respective second ends are fastened to the rotor housing part and are wound in opposite directions with a respective first section of their length resting against the inner surface of the cylindrical housing part portion of the stator housing part and with a respective second section of their length resting against the outer surface of the rotor housing part, so that a U-shaped turning section which reverses the winding direction is formed in each case between the two respective sections of the flat cable and of the flat ribbon; wherein the flat ribbon is a thin steel strip; and a permanent magnet is mounted in a region of the outer surface of the rotor housing part in such a way that the permanent magnet exerts an attractive effect on the second section of the length of the flat ribbon resting thereon.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/EP2024/068621, published in German, with an international filing date of Jul. 2, 2024, which claims priority to DE 10 2023 117 656.0, filed Jul. 4, 2023, the disclosures of which are hereby incorporated in their entirety by reference herein. TECHNICAL FIELD The present invention relates to a coil spring cassette including a stationary, at least partially cylindrical stator housing part and a cylindrical rotor housing part that is situated coaxially with respect to same and rotatable about its longitudinal axis, wherein a winding gap that is delimited by the inner lateral surface of the cylindrical portion of the exterior stator housing part and the outer lateral surface of the interior rotor housing part is formed, in which a flexible flat cable having at least one electrical conductor, and at least one flexible flat ribbon used for mechanical stabilization of 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 are fastened to the rotor housing part, and are wound in opposite directions with a respective first section of their length resting against the inner lateral surface of the stator housing part and with a respective second section of their length resting against the outer lateral surface of the rotor housing part, so that a U-shaped turning section which reverses the winding direction is formed in each case between the two respective sections of the flat cable and of the flat ribbon. BACKGROUND These types of coil spring cassettes are provided, for example, to allow reliable transfer of energy and/or data in motor vehicles, between connection points that are rotatably mounted in the steering wheel and connection points that are stationarily situated in the area of the steering column. Via the connection points of such a device, an airbag system, a steering wheel heating unit, a switching mechanism, etc., may be supplied with the voltage and signals necessary for them to function. Such a coil spring cassette has become known from EP 0 556 779 B1 (corresponding to U.S. Pat. No. 5,310,356), in which multiple flexible flat cables are accommodated inside an annular cavity in a housing. In each case, one end of the flexible flat cables is fastened to the stator part, and the respective other end of the flexible flat cables is fastened to a rotor part of the housing which is rotatable relative to the stator part. The flexible flat cables, with each of their two broad sides, are windable with at least one winding onto the axially oriented inner wall, and at a distance therefrom, are oppositely windable onto the axially oriented inner outer wall of the housing with at least one further winding, in each case via a U-shaped turning section. If a plurality of flat cables is needed for providing the required electrical connections, this plurality of flat cables is arranged in such a way that their respective end sections overlap on the outer lateral surface of the interior housing part and on the inner lateral surface of the exterior housing part, and the U-shaped turning sections of each of the flat cables generates an elastic pressure force that brings about secure contact of the internally or externally wound areas of the other flat cables with the lateral surfaces of the housing. If the number of flat cables needed for providing the required electrical connections is smaller than necessary for ensuring proper mechanical functioning of the coil spring cassette, so-called dummy cables are used instead of further flat cables. Dummy cables are elastic flat ribbons having mechanical properties equivalent to the flat cables, except that the former have no electrical strip conductors. Plastic ribbons made of PET, for example, are normally used as dummy cables. In practical operation, use of at least four or five cables or dummy cables has proven advantageous to ensure proper mechanical functioning of the coil 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 uniformly as possible over the circumference of the winding gap. In steering assemblies according to the so-called steer-by-wire principle, in which a mechanical steering spindle is no longer present, the steering wheel no longer has to be rotatable over multiple revolutions. Rotatability of even less than 360 degrees is necessary as a rule, which for the coil spring cassette means that it no longer has to encompass the entire steering spindle. Thus, the housing of the coil spring cassette no longer has to have a completely ring-shaped cross section. Rather, it is sufficient for the housing to form only a segment of a ring, thus providing additional installation space in this area in comparison to the background art. However, w