Torque-Free Pedestrian Hood Drive Device

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Solution Overview

Problem

Existing drive devices for lifting vehicle engine hoods to protect pedestrians often fail to deliver force effectively in a torque-free manner, which is crucial for swift hood raising.

Innovation Solution

A drive device featuring a pressure pipe with a piston driven by a gas source, where the piston rod is connected to a lifting gear through a torque-free mechanism, utilizing two aligned connection points to transmit force without rotational motion, and includes a stop ring for motion damping and a pyrotechnic gas generator for efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional drive device is used to lift the engine hood, then the hood can be raised, but the force transmission is not torque-free causing slower and less efficient operation

Engineering Contradiction:
Improvehood raising speedVSAvoidforce transmission mechanism
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The drive device is segmented into distinct functional components: a piston rod providing linear motion, a connection point for force application, and a lifting gear mechanism. This segmentation allows the linear force from the piston to be transmitted directly to the lifting gear without unnecessary rotational intermediaries, achieving torque-free force transmission and improving hood raising speed.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the piston rod is connected directly to the lifting gear, then force transmission is simplified, but the connection must accommodate both linear motion and lifting gear requirements

Engineering Contradiction:
Improveconnection mechanismVSAvoidconnection flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

A connection point acts as an intermediary element between the piston rod and the lifting gear. This connection point is designed to receive linear force from the piston rod and transfer it effectively to the lifting gear, accommodating both the linear motion requirement and the lifting gear's operational needs without requiring complex adaptive mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Power

If the piston is driven by a gas source in an angled pressure pipe, then the drive force is generated efficiently, but the force application point must be precisely aligned with the guideway

Engineering Contradiction:
Improvedrive force generationVSAvoidalignment precision
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

The connection point and the guideway are positioned such that the force application lies on the linear extension of the guideway, creating an equipotential alignment condition. This ensures that the drive force from the gas source, regardless of the pressure pipe angle, is applied precisely along the guideway's linear path, eliminating misalignment issues and ensuring efficient force transmission.

Inventive Principle:
Principle #12Equipotentiality

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

Enables the engine hood to be raised swiftly and efficiently, ensuring torque-free force transmission at the beginning of the drive motion, while maintaining structural integrity and safety features like motion damping and protection against accidental activation.

Implementation Method 1

The drive gas for the piston is supplied by a gas source disposed in a pressure pipe portion which is at an angle to the linear guideway

Methodology Applied
Scientific EffectPyrotechnic gas generator: Deflagration

Implementation Method 2

a stop ring arranged around the piston rod be provided at the front end of the piston in the drive direction. This stop ring may preferably consist of a motion-damping material

Methodology Applied
Scientific EffectMotion damping: Damping

Implementation Method 3

A piston rod is connected to the piston, the piston rod having having a rod portion projecting beyond a first guideway end of the pressure pipe

Methodology Applied
Scientific EffectLinear force transmission: Mechanical Force

Data Source

PatentEP2935906B1Drive device for lifting a vehicle engine hood adapted to protect pedestrians
Publication Date: 2018.08.22 KEY SAFETY SYSTEMS INC
  • EP2935906B1 patent drawingFigure 1~2
  • EP2935906B1 patent drawingFigure 3~6
  • EP2935906B1 patent drawingFigure 7

AI summary

The invention relates to a drive device for lifting a vehicle engine hood to protect pedestrians, said drive device comprising a pressure pipe (1) in which a piston (2) which can be driven by a drive gas can be moved along a linear guideway (3), a piston rod (4) connected to said piston (2), said piston rod (4) having a connection point (6) to be connected force-lockingly to a lifting gear for the engine hood at a rod portion (5) projecting beyond a first guideway end (11) of the pressure pipe, a second connection point (7) disposed at the second guideway end (12) located opposite the first guideway end (11), for force-locking support of the pressure pipe on the vehicle body, wherein said two connection points (6) and (7) are arranged at the pressure pipe (1) in line with the linear guideway (3) of the piston (2), and a gas source (8) supplying the drive gas, said gas source (8) being disposed in a pressure pipe portion (9) which is at an angle to the linear guideway (3).