Winding spring case

Description

[0001] The invention relates to a coil spring cassette with a stationary stator part and a rotor part arranged to rotate relative to it, and with a flat ribbon cable which is mechanically fixed to the stator part and the rotor part, and which establishes an electrical connection between the stator part and the rotor part, wherein the flat ribbon cable has at least one notch on at least one lateral edge section.

[0002] A coil spring cassette is known, for example, from the German patent application DE 10 2010 022 542 A1.

[0003] Clock spring cassettes are long-established and indispensable components, particularly in motor vehicles, for electrically connecting rotating elements such as the steering wheel and steering column. This electrical connection is typically achieved via a ribbon cable located between the stator and rotor sections of the clock spring cassette. During rotation, the cable winds and unwinds or shifts within the cassette. The ribbon cable can carry both electrical signals and electrical energy, potentially involving relatively high currents and voltages.

[0004] Japanese patent applications JP H08 227774 A and JP H08 227773 A each disclose coil spring cassettes with flat ribbon cables that have incisions in their edge regions. These incisions form elastic edge regions of the cable, which are intended to provide elastic support for the cable within the respective housing.

[0005] German patent application DE 196 04 797 A1 discloses a coil spring cassette according to the preamble of claim 1. The flat ribbon cable of this coil spring cassette is provided on its edge with a pair of rectangular indentations, which serve for fastening by an associated pair of flat retaining elements.

[0006] The maximum possible twist angle of a coil spring cassette is usually limited by the installation location. However, under unfavorable circumstances, a ribbon cable can still become severely strained and then break due to overload. An uncontrolled breakage of a ribbon cable can cause short circuits, which can lead to further faults and defects.

[0007] The task was to create a coil spring cassette that avoids or at least reduces the aforementioned disadvantages.

[0008] This problem is solved according to the invention by having the indentation be v-shaped.

[0009] The ribbon cable has a deliberately introduced mechanical weakening due to at least one notch. In the event of mechanical overload, the ribbon cable therefore tears at this selected, predefined point. The location of the notch is chosen so that, as a result of the tear, exposed conductors have as little opportunity as possible to form a short circuit.

[0010] The coil spring cassette designed according to the invention thus enables a significant limitation of damage in the event of a cable breakage in a simple manner.

[0011] It is particularly advantageous if the ribbon cable has two notches opposite each other on its two edges. This allows for a relatively straight tear edge in the event of a cable break.

[0012] It is also particularly advantageous if the ribbon cable is designed as a foil conductor. Apart from the well-known property that a relatively thin foil conductor can be particularly well accommodated in multiple layers inside a coil spring cassette, a foil conductor can also tear particularly easily under mechanical overload.

[0013] An embodiment of the invention will now be illustrated and explained with reference to the drawing. The drawing shows Figure 1: A section of a coil spring cassette. Figure 2: A first embodiment of a flat ribbon cable. Figure 4: A second embodiment of a flat ribbon cable.

[0014] The Figure 1Figure 1 schematically shows a section of a coil spring cassette designed according to the invention. The coil spring cassette is not described in detail here, as its basic structure and function can be assumed to be known from publications such as the aforementioned German patent application DE 10 2010 022 542 A1.

[0015] A coil spring cassette typically comprises a stator part 10 and a rotor part 20 which is rotatably arranged relative to the stator part 10. A flat ribbon cable 30 is arranged between the stator part 10 and the rotor part 20, which transmits electrical signals or electrical energy between the stator part 10 and the rotor part 20.

[0016] For this purpose, the flat ribbon cable 30 is mechanically and electrically connected to both the stator part 10 and the rotor part 20. This is shown schematically in the Figure 1A conductor connector 50 mechanically and electrically fixes one end of the ribbon cable 30 to the stator part 10. From there, the ribbon cable 30 extends over an edge 14 on the stator part 10, and, forming an internal twist 36, into a gap formed between a wall 12 on the stator part 10 and the rotor part 20.

[0017] Not shown in detail in the drawing, the flat ribbon cable 30 is arranged within the space in several winding layers or forming deflection loops. As a result, when the rotor part 20 rotates relative to the stator part 10, at least parts of the flat ribbon cable 30 wind up or unwind.

[0018] To protect a flat ribbon cable 30 from overload due to excessive tensile stresses, the length and arrangement of the flat ribbon cable 30 are designed for a specified maximum rotation angle range. Devices to limit the rotation angle range are also sometimes provided. However, these are particularly difficult to implement when the coil spring cassette is designed for more than one complete revolution.

[0019] In any case, malfunctions cannot be ruled out that could lead to overload and breakage of the ribbon cable 30. If the ribbon cable 30 breaks, conductors 38 are usually exposed, which can lead to short circuits and other faults and defects, the nature and extent of which can lead to a safety-critical condition, such as the unintended deployment of the airbag.

[0020] According to the invention, a targeted weakening of the material on the flat ribbon cable 30 is provided to create a point where breakage can occur in the event of mechanical overload. This is achieved simply and advantageously by a notch 41 made on the edge of the flat ribbon cable 30.

[0021] The notch 40 is, as in the Figure 1 The notch 40 is shown as a triangular incision in an edge section 32 of the flat ribbon cable 30. Advantageously, the edge of the flat ribbon cable 30 is chosen for the incision 40, as this is where the greater tensile stress occurs in the event of a high tensile load on the flat ribbon cable 30. This allows for a quick and relatively smooth break.

[0022] Preferably, the notch 40 is provided near one end of the ribbon cable 30, and thus in the vicinity of a conductor connector 50. Alternatively, a notch can be provided at each end of the ribbon cable 30, and thus both near the stator-side conductor connector 50 and near the rotor-side edge connector (not shown here).

[0023] Alternatively, a notch 40 can also be made in a middle area of ​​the ribbon cable 30.

[0024] The Figures 2 and 4 Figure 1 illustrates several advantageous possibilities for providing one or more notches 41, 43, 44 on a flat ribbon cable 30.

[0025] In the Figure 2 The flat ribbon cable 30, as already mentioned in the Figure 1The figure shows a single triangular indentation 41. The indentation 41 is narrow compared to the width of the ribbon cable 30 and is primarily made in the insulating sheath layer of the ribbon cable 30, whereby the material of the conductors 38 can be partially incorporated into the formation of the indentation.

[0026] Figure 4 Figure 30 shows a further embodiment of a flat ribbon cable 30, which has a notch 43, 44 on each of its opposite edge sections 32, 34, arranged opposite each other. A tear starting on the first edge section 32 and running perpendicular to the first edge section 32 can thus find a target point through the notch 44 on the second edge section 34, through which the complete tearing of the flat ribbon cable 30 can occur particularly quickly and reliably. Reference sign

[0027] 10Stator part 12Wall 14Edge 20Rotor part 30Flat ribbon cable 32First edge section 34Second edge section 36Twist 38Wires 40, 41, 43, 44Notch 50Wire connector

Claims

1. Coil spring cassette with a fixed stator part (10) and a rotor part (20) arranged rotatably relative thereto, and with a flat ribbon cable (30) which is mechanically fixed to the stator part (10) and the rotor part (20) and which provides an electrical connection between the stator part (10) and the rotor part (20), wherein the flat ribbon cable (30) has at least one notch (40, 41, 43, 44) on at least one lateral edge section (32, 34), characterized in that that the notch (40, 41, 43, 44) is V-shaped.

2. Coil spring cassette according to claim 1, characterized in that the flat ribbon cable (30) is designed as a foil conductor.

3. Coil spring cassette according to claim 1, characterized in that the flat ribbon cable (30) has two notches (43, 44) mutually opposing each other on its two lateral edge sections (32, 34).