Adjustable Steering Column Breakaway Force Control
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Solution Overview
Problem
Existing adjustable steering columns in vehicles face the challenge of not being able to break loose with a precisely defined breakaway force during a crash, which can impair the energy absorption mechanism.
Innovation Solution
The coupling device features a pin-shaped holding element with a head fixed in a counter-holder, where the thickness of elements between the head and counter-holder changes from a first thickness to a second, allowing the actuating unit to move relative to the transmission device only when a predetermined breakaway force is exceeded, enabling the energy absorption device to engage during a crash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If riveted connections are used to attach the coupling element to the actuator, then the connection provides structural strength, but the breakaway force cannot be precisely adjusted to requirements
Solution Approach 1:
The invention changes the parameter of connection strength by using adjustable friction elements (washers, springs, or friction plates) between the coupling element and actuator. By varying the friction coefficient and normal force through these elements, the breakaway force can be precisely adjusted to match specific safety requirements, resolving the contradiction between structural strength and breakaway force precision.
2Stability of the object's composition
If the coupling device is firmly connected during normal operation, then stability is maintained, but the energy absorption device cannot be activated in a crash
Solution Approach 1:
The invention transforms the static connection into a dynamic one by introducing friction-based coupling elements that can transition between locked and slipped states. During normal operation, friction maintains stable connection, while during crashes, the connection dynamically transitions to allow relative movement, activating the energy absorption device. This resolves the contradiction between stability and reliability.
Solution Approach 2:
The invention introduces friction elements (washers, springs, or friction plates) as intermediary components between the coupling element and actuator. These intermediaries mediate the force transmission, providing controlled friction that maintains stability during normal operation but allows controlled slippage during crashes to activate energy absorption, thus resolving the contradiction between stability and activation reliability.
3Ease of operation
If adjustment forces are transmitted through the energy absorption device during normal operation, then the actuator can be adjusted, but the function of the energy absorption device is impaired
Solution Approach 1:
The invention segments the force transmission path by introducing a separate adjustment force transmission path through friction elements, distinct from the energy absorption device. This allows adjustment forces to be transmitted through the friction-based coupling mechanism without involving the energy absorption device, preserving its function while maintaining actuator adjustability.
Solution Approach 2:
The invention introduces friction elements as intermediary components that provide a separate force transmission path for adjustments. These intermediaries handle adjustment forces through friction-based coupling, preventing them from being transmitted through the energy absorption device and thus preserving the energy absorption function while enabling actuator adjustability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design ensures that the steering column breaks loose at a defined force threshold during a crash, allowing the energy absorption device to absorb energy effectively while maintaining stability under normal driving conditions.
Implementation Method 1
the energy absorption device comprises at least one bending wire, whose first end is connected to the actuator and whose second end is connected to the coupling device. In the event of a crash, the connection between the coupling device and the actuator is severed, thus allowing movement between the actuator and the transmission device and enabling the energy absorption device to absorb energy
Implementation Method 2
The head of the retaining element rests with preload on the raised edge region. In the event of a crash, relative movement occurs between the retaining element and the coupling element, such that the static friction force acting between the head of the retaining element and the raised edge area is exceeded by the force transmitted to the steering shaft
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The aim of the invention is to provide an adjustable steering column (1) for a motor vehicle, comprising an adjusting unit (3) for mounting a steering shaft (2) such that it rotates about a longitudinal axis (7), and a support unit (4) in which the adjusting unit (3) is mounted such that it can be axially moved in the direction of the longitudinal axis (7) of the steering shaft (2) by means of a motor-driven longitudinal-adjustment drive (8) arranged on the support unit (4), and also comprising a transmission device that is coupled to both the adjusting unit (3) and the longitudinal-adjustment drive (8), in which an energy absorption device (29) is provided, which absorbs energy in the event of the adjusting unit (3) moving in relation to the transmission device, in which a coupling device is provided, which is connected to the adjusting unit (3) and is connected to the transmission device, and in which, in the event of a crash, in which a force exceeding a pre-determined value acts on the steering shaft (2) in the direction of the longitudinal axis (7), the connection of the coupling device to the adjusting unit (3) and/or the transmission device is interrupted such that a movement between the adjusting unit (3) and the transmission device is allowed. Additionally said steering column breaks away with a defined breakaway force in the event of a vehicle crash. To this end, the coupling device comprises a rod-type holding element (33, 34) with a head (37, 42) fixed in a clamp (36, 360), wherein at least one element is arranged between the clamp (36, 360) and the head (37, 42), said element being secured to the transmission device or the adjusting unit (3), and wherein a second thickness (d) of all elements arranged between the clamp (36, 360) and the head (37, 42) is smaller, in the event of a movement of the adjusting unit (3) in relation to the transmission device, than a first thickness (D) of all elements in the event of the adjusting unit (3) and the transmission device being fixed in the position thereof in relation to each other.