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Adaptive Longitudinal Front End Disclosure Number: IPCOM000127611D
Publication Date: 2005-Sep-05
Document File: 7 page(s) / 887K

Publishing Venue

The Prior Art Database


A bumper assembly is mounted on a structure which can change the stifness of the front end when a crash is identified. The structure is either an extendable structure that on receiving a fire from some predictive crash sensor will extend by a given distance or an additional section of structure that can eitheir released or engaged to the longitudinals when the system receives the fire signal.

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Page 1 of 7

Adaptive Longitudinal Front End

Background of the invention:

In a high speed impact a significant factor in occupant injury is cabin intrusion, i.e. the front of the car being forced backwards into the passenger compartment, due to the crushing of the structure around the bumper and engine bay. The best way to avoid this problem is to make the frontal areas of the car very stiff while maintaining a progressive collapse from the bumper towards the vehicle cabin to enable them to withstand the impact.

In a low speed impact cabin intrusion is not a significant problem as the energies involved are not sufficient to crush the structure, however injuries can be caused by the rapid deceleration of the passenger compartment, and hence the deceleration of the occupants. The best way to avoid this problem is to make the front of the car as soft as possible to enable the structure to crush and absorb the energy, hence allowing the passenger compartment to decelerate over a longer period of time, this will subject the occupant to less severe deceleration forces.

Clearly high speed and low speed considerations drive conflicting requirements of the stiffness in the front end of the vehicle, and to satisfy both is to strike a balance, potentially compromising, to some extent, either or both considerations.

In order to deliver improved safety performance whilst maintaining aesthetic proportions and design, an active system could be employed to change the stiffness of the front end of a vehicle when a crash event is identified. This would rely on predictive crash sensing, as an active system would need to be 'deployed' prior to impact in order to deliver benefits.

Description of the invention:

(1) Hydraulic actuator Concept

Hydraulic actuator fits inside longitudinal

Hydraulic fluid from auxiliary reservoir


Variable exhaust



Solenoid (normally closed) opens to allow hydraulic fluid to pressurise actuator. Solenoid closes when actuator has reached full travel (100mm)

Gap to allow longitudinal to crush once actuator stroked

Disclosed anonymously 1/7

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Hydraulic Actuator - Functional description

The hydraulic actuator concept is designed to work in conjunction with Radar Enhanced Crash Sensing (imminent collision sensing radar). When the sensing system has established a definite frontal impact is about to occur, the inlet valve (solenoid operated system) opens to allow the pressurised hydraulic fluid into the cylinder. The piston extends the front bumper system forward of the vehicle by 100mm and the solenoid then closes (normally closed).

During the crash, the variable exhaust valve controls the collapse rate in order to provide the required crush characteristics for a high speed collision.

A gap must be present between the actuator and the longitudinal to allow the longitudinal to crush once the actuator has stroked.

The system is designed to be re-settable...