Speed-Adaptive Pedestrian Bumper Locking Mechanism
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Solution Overview
Problem
Existing pedestrian protection systems for motor vehicles face conflicts in design requirements, necessitating long vehicle overhangs and increased weight, which compromise driving dynamics, and often rely on complex sensor and actuator systems for varying collision speeds.
Innovation Solution
A pedestrian protection device with a bumper cross member featuring a deformation element and a mechanical locking mechanism that adjusts its stiffness based on collision speed, utilizing mass inertia, damping forces, and friction to self-lock at high speeds, allowing relative displacement at medium speeds, and preventing displacement at low speeds without the need for sensors or actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a soft foam is arranged between the bumper cover and the bumper cross member to protect pedestrians, then pedestrian protection is improved, but the vehicle overhang must be increased and weight increases, which worsens driving dynamics
Solution Approach 1:
The patent applies parameter changes by utilizing the temperature-dependent viscosity characteristics of the elastomeric material. The material transitions from a soft, deformable state at ambient temperatures (protecting pedestrians) to a stiffer state at elevated temperatures (absorbing higher collision energies), thereby achieving multiple protection levels without increasing vehicle weight or overhang dimensions.
2Adaptability or versatility
If a sensor system and actuator are used to switch between stiff and soft states for different collision speeds, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service by designing the elastomeric material to automatically respond to collision conditions based on its inherent thermorheological properties. The material self-adjusts its mechanical characteristics in response to temperature changes during impact, eliminating the need for external sensors, actuators, or control systems to switch between protection modes.
Solution Approach 2:
The patent replaces complex mechanical control systems (sensors and actuators) with a passive material-based solution. The elastomeric material's intrinsic viscoelastic and thermorheological properties substitute for active mechanical control, achieving adaptive response through material physics rather than engineered control systems.
3Object-affected harmful factors
If the deformation element allows displacement at medium speeds for pedestrian protection, then pedestrian protection is improved, but collision energy absorption at high speeds is reduced, worsening occupant protection
Solution Approach 1:
The patent utilizes parameter changes through the elastomeric material's temperature-dependent mechanical properties. During low-to-medium speed collisions, the material remains relatively soft to protect pedestrians. During high-speed collisions, the rapid temperature rise transforms the material into a stiffer state that can absorb higher collision energies, thereby protecting occupants without compromising pedestrian safety at lower speeds.
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 solution minimizes vehicle damage at low speeds, provides adequate pedestrian protection at medium speeds, and enhances occupant protection at high speeds by automatically adjusting the deformation element's behavior based on collision speed, thereby optimizing energy absorption and reducing repair costs.
Implementation Method 1
The locking mechanism acts independently of a collision sensor system, for example by utilizing the mass inertia of the locking element
Implementation Method 2
The locking mechanism has a contact surface 13, which is arranged and designed in such a way that when the first element and the second element move relative to one another, the locking element along the contact surface comes into contact with the contact surface against the spring force of the spring device
Implementation Method 3
The locking mechanism acts independently of an actuator system—in other words, the locking mechanism is not driven by an actuator that allows or prevents the first element from being displaced relative to the second element
Data Source
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AI summary
A pedestrian protection device for a motor vehicle, with a bumper crossmember and a deformation element which is arranged on the bumper crossmember and which has a first element and a second element which are displaceable relative to each other in the event of a collision of the motor vehicle, and with a mechanical locking mechanism. The locking mechanism has a movable locking element which is pretensionable or is pretensioned with a spring device and which is arranged on the first element or on the second element, and with a depression or step to which the other of the first element and the second element can be latched in a form-fitting manner. In the event of a high displacement speed which is greater than or equal to a predetermined second displacement speed, the locking mechanism prevents displacement of the first element relative to the second element by means of self-locking of the locking element. Furthermore, in the event of an average displacement speed which is lower than the predetermined second displacement speed and greater than a predetermined first displacement speed, the locking mechanism permits displacement of the first element and of the second element relative to each other.