Wiper Arm Torsion Spring Nesting for Height Reduction

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Solution Overview

Problem

Existing wiper arm designs have a large overall height due to the protrusion of spiral springs, which is not efficiently managed by current technologies.

Innovation Solution

The wiper arm incorporates a torsion spring arranged within a joint formed by an articulated and lever part, where the torsion spring is embedded between U-shaped side elements, reducing overall height by creating a compressive force and allowing for a pivoting movement while being compactly integrated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a spiral spring is used in the wiper arm, then the wiper arm can provide the necessary force for lever movement, but the overall height of the wiper arm increases due to spring protrusion

Engineering Contradiction:
Improveforce for lever movementVSAvoidoverall height of wiper arm
Core Design Contradiction:
ForceVSLength of stationary object

Solution Approach 1:

The torsion spring is nested within the joint part structure, specifically positioned between the articulated part and lever part. The spring is arranged radially inward relative to the joint axis, allowing it to be contained within the existing structural envelope rather than protruding outward. This nesting approach eliminates the need for additional space in the height direction while maintaining the spring's functional integrity for providing torque to the lever part.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The spring arrangement transitions from a vertical/protruding configuration to a radial/in-plane configuration. Instead of the spring extending in the height direction (z-axis), it is positioned in the radial direction (r-axis) within the joint part, utilizing the planar space between the articulated part and lever part. This dimensional reorientation allows the spring to provide necessary force while maintaining a compact overall height.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Length of stationary object

If the torsion spring is arranged within the joint part, then the overall height is reduced, but the installation space becomes limited

Engineering Contradiction:
Improveoverall height of wiper armVSAvoidinstallation space for spring
Core Design Contradiction:
Length of stationary objectVSArea of stationary object

Solution Approach 1:

The joint part is segmented into distinct functional zones: the articulated part, the lever part, and the intermediate space between them. The torsion spring is specifically positioned in this intermediate zone, utilizing the gap that naturally exists between the articulated part and lever part. This segmentation allows the spring to be installed in the available radial space without requiring additional vertical clearance, effectively using otherwise wasted space in the joint mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The joint part structure is designed with locally optimized features to accommodate the spring, including specific mounting surfaces and attachment points on the articulated part and lever part. The spring is positioned at a specific radial location where sufficient clearance exists between moving components, utilizing the non-uniform distribution of space within the joint mechanism to find an optimal installation position that maintains both compact height and adequate spring clearance.

Inventive Principle:
Principle #3Local quality

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 effectively reduces the overall height of the wiper arm while maintaining functionality, allowing for efficient operation and reduced installation space, with the torsion spring providing the necessary force for the lever's movement and prestressing the disk.

Implementation Method 1

The lever part can be tilted from this position. It is tilted in the direction of the joint part. The lever part performs a pivoting movement away from the disk. In the position on the disc, the lever part is held and prestressed by a spring.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The spring is designed as a torsion spring so that the overall height can be effectively reduced. The torsion spring is arranged in the area of the joint.

Methodology Applied
Scientific EffectTorsion spring: Torsion Spring

Data Source

PatentEP3359427B1Wiper arm and windscreen wiper system for a motor vehicle
Publication Date: 2020.12.16 ROBERT BOSCH GMBH
  • EP3359427B1 patent drawingFigure 1
  • EP3359427B1 patent drawingFigure 2
  • EP3359427B1 patent drawingFigure 3

AI summary

A wiper arm and a windscreen wiper system, wherein the wiper arm comprises a joint part and a lever part and a spring, wherein the parts form a common joint. The spring is embodied here as a torsion spring.