Progressive Spring Connecting Element for Brake Force Measurement
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Solution Overview
Problem
Conventional vehicle brake systems lack effective measurement of actuating force, primarily focusing on pedal travel rather than force measurement, which limits precise braking force control and comfort.
Innovation Solution
A connecting element with a progressive spring characteristic and a deformation measuring device, comprising series-connected spring elements with varying rates, measures deformation to quantify actuating force, enhancing resolution and signal quality for braking force control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid piston rod is used to transmit actuating force, then force transmission is direct and reliable, but measurement of actuating force becomes difficult and the system lacks deformation sensitivity
Solution Approach 1:
The connecting element changes its mechanical parameter (spring rate) dynamically through progressive spring characteristic. The spring rate increases with deformation, providing both sensitivity at low forces and stability at high forces, enabling force measurement without requiring a completely different structure
Solution Approach 2:
The rigid mechanical connection is replaced with an elastic spring-based connecting element. This substitution enables the system to measure force through deformation while still transmitting the actuating force reliably to the master cylinder piston
2Measurement precision
If a linear spring characteristic is used in the connecting element, then the relationship between deformation and force is simple, but resolution at low forces is insufficient and pedal feel is unrealistic
Solution Approach 1:
The spring rate parameter is changed from constant (linear) to variable (progressive). This allows the connecting element to provide high resolution measurement at low forces while delivering realistic pedal feel across the entire operating range
Solution Approach 2:
The connecting element transitions from a static linear spring to a dynamic progressive spring whose characteristics change with deformation. This dynamic behavior mimics real brake system pedal feel while improving measurement resolution
3Productivity
If the connecting element has high stiffness, then force transmission is efficient, but deformation sensitivity for measurement decreases
Solution Approach 1:
The spring rate parameter is made variable rather than constant. At low deformations, the spring rate is low providing high sensitivity for measurement. At high deformations, the spring rate increases providing efficient force transmission and rapid braking response
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
The solution provides improved braking force control by increasing deformation sensitivity at low forces and stiffness at high forces, reducing brake pedal inertia and enhancing measurement resolution, thus optimizing braking performance.
Implementation Method 1
The connecting element has spring elements (6, 11) connected in series with different spring rates (progressive spring characteristic)
Implementation Method 2
a deformation measuring device (14) for measuring a deformation of the connecting element (1) by an actuating force exerted on the connecting element
Data Source
Figure 1~2
AI summary
The invention relates to a connecting element (1) connecting a brake pedal (2) to a brake force amplifier (3) of a vehicle brake system. The invention proposes to dispose a helical compression spring (7) as a first spring element (6) and a rubbery-elastic reaction disk (10) as a second spring element (11) between a pedal rod (4) and a piston rod (12) of the connecting element (1), said spring elements being installed in series due to the arrangement thereof. Due to the higher spring rate of the reaction disk (10) preferably increasing with load, the connecting element (1) has a progressive spring characteristic line. As soon as the pedal rod (4) contacts the reaction disk (10) the helical compression spring (7) and the reaction disk (10) act in parallel and serially such that the progression of the total spring characteristic line further increases.