Spindle Drive Nominal Break Point for Tailgate Safety

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Solution Overview

Problem

Existing spindle drives for motor vehicle closing elements lack sufficient safety measures to maintain the retaining function and prevent damage to drive components when the axial load limit is reached, leading to potential safety risks and loss of functionality.

Innovation Solution

Incorporating a nominal break point in the drive train between the drive unit and the spindle-nut gear, which interrupts the force flow and torque transmission upon reaching the axial load limit, allowing the drive connections to remain intact and the spindle drive to retain its function, even after separation, by using a telescopic housing and a spring arrangement to ensure the drive components remain housed and operational.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a nominal break point is provided in the drive train to interrupt force flow when axial load limit is reached, then the drive connections remain intact and the connection to the motor vehicle is retained, but the drive train separates into two parts which may lose retaining function

Engineering Contradiction:

Improvedrive connection integrityVSAvoidspindle drive unity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The drive train is segmented at a nominal break point located between the drive unit and spindle-nut gear, allowing controlled separation into first and second component units while preserving drive connection integrity to the motor vehicle

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first and second component units are nested within a common housing structure with telescopic housing parts that provide axial guidance and retain both units even after separation, maintaining the spindle drive as one integrated unit

Inventive Principle:

Principle #7Nested doll (Nesting)

2Strength

If the nominal break point is arranged to separate the drive train between drive unit and spindle-nut gear, then damage to drive components is prevented, but the axial guidance and retaining function may be lost

Engineering Contradiction:

Improvedrive component protectionVSAvoidaxial guidance function

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The housing with telescopic housing parts acts as an intermediary structure that maintains axial guidance between the separated first and second component units, preserving the guiding function without requiring continuous drive train integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The housing structure is designed beforehand to accommodate and guide the separated component units, ensuring they remain axially guided and retained even after nominal break point separation occurs

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11821250B2Spindle drive for a closure element of a motor vehicle

Publication Date: 2023.11.21 BROSE FAHRZEUGTEILE GMBH & CO KG

AI summary

The invention concerns a spindle drive for a closing element (3) of a motor vehicle (4), wherein in a drive train (14) of the spindle drive (1), a drive unit (5) is provided together with a spindle-nut gear (11) located drivingly downstream of the drive unit (5), with geometric spindle axis (A) running in the axial direction (X), in order to generate linear drive movements of a spindle-side drive connection (12a) relative to a nut-side drive connection (12b) between a retracted position and an extended position of the spindle drive (1), wherein in the drive train (14) a nominal break point (17) is provided which separates the drive train (14) at a predetermined axial limit load acting on the spindle drive (1) via the drive connections (12a, 12b), in particular a tensile load in the direction of the extension position. It is proposed that the drive train (14) is separated via the nominal break point (17) between the drive unit (5) and the spindle-nut gear (11).