Coil spring box

Abstract

The invention relates to a coil spring box, comprising a stationary stator housing part and a rotatable rotor housing part, between which a winding gap is formed, in which a flexible flat cable having an electrical conductor and a flexible flat tape are arranged in such a way, the flat cable and the flat belt are wound in opposite directions in such a way that respective first sections of the flat cable and the flat belt abut against the inner side surface of the stator housing part and respective second sections of the flat cable and the flat belt abut against the outer side surface of the rotor housing part. According to the invention, the flat cable and the flat belt are arranged in the rotor housing part such that a U-shaped deflection section which reverses the winding direction is formed between the respective two sections of the flat cable and the flat belt, characterized in that the flat belt is designed as a thin steel belt, and the permanent magnets are mounted in the region of the outer side surface of the rotor housing part such that the flat cable and the flat belt can be wound around the rotor housing part. A suction effect is generated on the section of the flat belt which is attached to the section of the flat belt.

Description

TECHNICAL FIELD

[0001] The invention relates to a coil spring box with a fixed, at least partially cylindrical stator housing part and a coaxially arranged, cylindrical rotor housing part which is rotatable about its longitudinal axis, wherein a winding gap is formed which is bounded by the inner lateral surface of the cylindrical portion of the stator housing part which is on the outside and the outer lateral surface of the rotor housing part which is on the inside, in which at least one flexible flat cable with electrical conductors and at least one mechanically stable flexible flat ribbon for the flat cable are arranged in such a way that the respective first end of the flat cable and the flat ribbon is fixed to the stator housing part and the respective second end of the flat cable and the flat ribbon is fixed to the rotor housing part, and the flat cable and the flat ribbon are wound in opposite directions with their respective first section of length against the inner lateral surface of the stator housing part and with their respective second section of length against the outer lateral surface of the rotor housing part, so that between the respective two sections of the flat cable and the flat ribbon a U-shaped turning section of the opposite winding direction is formed. BACKGROUND

[0002] Such coil spring boxes are provided, for example, for the secure transmission of energy and / or data in motor vehicles between a connection point which is rotatably held in a steering wheel and which is arranged positionally fixed in the region of a steering column. Via the connection point of such a device, for example, an airbag system, a steering wheel heating device, a switching device, etc. can be supplied with the voltage and signals necessary for its function.

[0003] From EP 0 556 779 B1 a coil spring box is known in which a plurality of flexible flat cables are accommodated in an annular cavity of the housing. Respective one end of the flexible flat cables is fixed to a stator part and the respective other end of the flexible flat cables is fixed to a rotor part of the housing which is rotatable relative to the stator part. The flexible flat cables are respectively wound with their two broad sides via a respective U-shaped turning section in at least one turn onto an axially aligned inner wall and oppositely in at least one further turn spaced therefrom onto an axially aligned outer wall of the housing.

[0004] As soon as a plurality of flat cables is required for the provision of the necessary electrical connections, these are arranged in such a way that their respective end sections overlap on the outer lateral surface of the housing part which is on the inside and on the inner lateral surface of the housing part which is on the outside, and the U-shaped turning section of each flat cable generates an elastic pressure which causes a reliable lying of the wound regions of the other flat cables on the housing lateral surfaces, either on the inside or on the outside.

[0005] If, in order to provide the necessary electrical connections, a smaller number of flat cables than necessary for ensuring the intact mechanical function of the clock spring housing is to be used, so-called dummy cables are used instead of additional flat cables. These are elastic flat strips which have mechanical properties equivalent to those of flat cables, but which, unlike them, do not comprise electrical conductor strips. As dummy cables, plastic strips composed, for example, of PET are used as standard. In practical use, the use of at least four or five cables or dummy cables proves to be advantageous in order to ensure the intact mechanical function of the clock spring housing. The four or five cables or dummy cables must be arranged here in such a way that the U-shaped turning sections of the reverse winding direction are distributed as uniformly as possible over the circumference of the winding gap.

[0006] In steering devices according to the so-called steer-by-wire principle, in which there is no longer a mechanical steering shaft, the steering wheel no longer has to be rotatable through many revolutions. In general, even less than 360 degrees of rotatability is required, which for the clock spring housing means that the clock spring housing no longer needs to encompass the entire steering shaft. The housing of the clock spring housing is therefore no longer necessarily completely annular in cross section. Rather, it is sufficient if the housing only constitutes a part of a ring, whereby additional construction space is obtained in this area compared to the prior art.

[0007] In the case of a plurality of flat cables, these then have to be arranged more closely to one another, so that the above-mentioned mechanical stabilization by means of the U-shaped turning sections of the flat cables distributed uniformly over the circumference can no longer be achieved. It has shown that, in particular in the region of the connection of the flat cables to the rotor housing part situated inside, the flat cables can no longer reliably lie against the outer side surface of the rotor housing part.

[0008] A further form of mechanical stabilization is therefore required here, which provides the clock spring housing according to the application in a simple and robust manner. SUMMARY

[0009] According to the application, this is achieved in that at least one flat strip is embodied as a thin steel strip, and in that at least one permanent magnet is mounted in the region of the outer side surface of the rotor housing part in such a way that it exerts an attractive action on a second section of the length of the flat strip lying there against. BRIEF DESCRIPTION OF DRAWINGS

[0010] Advantageous design variants of the object according to the application are explained further by means of the embodiments shown in the drawings.

[0011] In the drawings:

[0012] Figure 1 schematic view in cross section of an embodiment of a clock spring housing according to the application

[0013] Figure 2 shows a schematic view in cross section of a clock spring housing according to the prior art DETAILED DESCRIPTION

[0014] In order to illustrate the general working principle of the coil spring box referred to here, a coil spring box according to the prior art with the minimum number of four cables or virtual cables mentioned previously is shown schematically in cross section in Figure 2. The coil spring box consists essentially of a housing with a stator housing part 1 and a rotor housing part 2 and a flexible flat cable 6 or flat belts 7 as virtual cables which are accommodated in the annular cavity of the housing which constitutes a winding gap 5. In the known embodiment shown here there are three flexible flat belts 7 without electrical conductors and one electrical flat cable 6. The flat cable 6 is shown by a broken line in the drawing.

[0015] The rotor housing part 2 which is shown inside in the embodiment rotates about its own longitudinal axis and thus also about the longitudinal axis of the coaxially arranged stator housing part 1. The winding gap 5 in which the flexible flat cable 6 is accommodated is constituted by the inner side surface 3 of the stator housing part 1 and the outer side surface 4 of the rotor housing part 2. The flexible flat cable 6 is fixed with its first end on the stator housing part 1 and with its second end on the rotor housing part 2 and is arranged in the winding gap 5 in such a way that the section of its length adjacent to its first end is wound in the opposite direction lying against the inner side surface 3 of the stator housing part 1 and the section of its length adjacent to its second end is wound in the opposite direction lying against the outer side surface 4 of the rotor housing part 2. Between the two respective sections of the flat cable 6 there is a U-shaped turn section 6' which reverses the winding direction. In the event of a rotation of the rotor housing part 2 in one or the other direction, the U-shaped turn section 6' moves along the circumference of the winding gap 5 and the flat cable 6 is unwound on one side and wound on the other side. In order to mechanically stabilise the flat cable 6, in particular to ensure a firm lying against the side surfaces 3, 4 of the end sections, three additional flexible flat belts 7 are accommodated in the winding gap 5 in the same way as the flat cable 6, more precisely: the four U-shaped turn sections 6', 7' of the flat cable 6 and the three flat belts 7 are arranged at the same angle of approximately 90° to one another. The respective first and second ends of the flat belts 6 and 7 which are fixed on the stator housing part 1 on the one hand and on the rotor housing part 2 on the other hand also have the same angle of approximately 90° to one another here respectively.

[0016] In Figure 1In the shown coil spring cartridge according to the application, the housing is no longer completely annular in cross section, but is constructed as only a part of a ring, and a different arrangement of the flat cables 6 and flat strips 7 has to be made. The respective first and second end portions of the flat cables 6 and, in this case, only one flat strip 7 are fixed at identical locations on the stator housing part 1 and on the rotor housing part 2, respectively. Unlike in the above-described implementation according to the prior art, in which all flat cables 6 and flat strips 7 can at least in theory be implemented to be substantially the same length, here their lengths have to be different. The flat strip 7, which is located inside with respect to the winding gap 5, has the shortest length here. The flat cables 6, which are located outside with respect to the winding gap 5, are the longest, and in this implementation are also the only ones which lie directly not only against the inner side surface 3 of the stator housing part 1, but also against the outer side surface 4 of the rotor housing part 2.

[0017] The flat strip 7, which is located inside with respect to the winding gap 5, is implemented as a thin steel strip and serves only for mechanical stabilization of the flat cables 6 according to the application. For this purpose, permanent magnets 8 are mounted in the region of the outer side surface 4 of the rotor housing part 2 in such a way that they exert an attractive action on the length section of the flat strip 7 which lies there against. The region of the flat cables 6 which is located between the flat strip 7 and the outer side surface 4 of the rotor housing part 2 is thus fixed to the outer side surface 4 of the rotor housing part 2 by the flat strip 7. The strength and the region range of the attractive action on the flat strip 7 can be varied by the number and the strength of the permanent magnets 8 used. This makes it possible, for example, to adapt to different maximum ranges of angles of rotation or to different numbers of flat cables 6 present. In the implementation shown here, there are three permanent magnets 8.

Claims

1. A coiled spring box comprising a fixed, at least partially cylindrical stator housing component (1) and a cylindrical rotor housing component (2) coaxial with the stator housing component and rotatable about its longitudinal axis, wherein, A winding gap (5) is formed by the inner side surface (3) of the cylindrical portion of the stator housing component (1) located on the outside and the outer side surface (4) of the rotor housing component (2) located on the inside, wherein at least one flexible flat cable (6) having an electrical conductor and at least one flexible flat strip (7) for mechanical stability of the flat cable (6) are arranged such that the first ends of the flat cable (6) and the flat strip (7) are respectively fixed to the stator housing component (1) and the second ends of the flat cable (6) and the flat strip (7) are respectively fixed to the rotor housing component (2), and the flat cable (6) and the flat strip (7) are respectively connected at their respective lengths. A portion of the stator housing component (1) is attached to the inner side surface (3) of the stator housing component (1), and a second portion of each of their lengths is attached to the outer side surface (4) of the rotor housing component (2) in opposite directions, such that a U-shaped turning segment (6′, 7′) with reverse winding direction is formed between each of the two portions of the flat cable (6) and the flat strip (7), characterized in that at least one of the flat strips (7) is implemented as a thin steel strip, and at least one permanent magnet (8) is mounted in the region of the outer side surface (4) of the rotor housing component (2) such that it attracts the second portion of the length of the flat strip (7) attached there.

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