Air Suspension Level Control Using Chassis-Axle Capacitance

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Solution Overview

Problem

Existing electronic level control systems for air-sprung vehicles require separate, externally installed capacitive height sensors, which are costly and complex, and do not efficiently integrate with the vehicle's components.

Innovation Solution

The system utilizes the chassis and axle as a capacitive height sensor, forming a capacitor with a variable electrical capacitance that changes with their mutual distance, allowing the electronic control unit to generate a control signal for the solenoid valve without additional sensors, using a circuit with a DC voltage source, charging resistor, and time-voltage measuring unit to calculate the capacitance and determine the distance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate capacitive height sensors are installed externally on the vehicle, then the vehicle height can be measured, but the device complexity and cost increase

Engineering Contradiction:
Improvevehicle height measurementVSAvoidsensor installation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the height measurement function with the existing vehicle chassis and axle components. The chassis and axle themselves form the capacitive sensor elements, eliminating the need for separate external sensors. This combining of measurement function with structural components directly reduces device complexity while maintaining measurement capability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The chassis and axle components serve dual purposes: they provide structural support for the vehicle and simultaneously function as the capacitive height sensor. This multi-functionality eliminates the need for dedicated separate sensors, reducing both complexity and cost while achieving accurate height measurement

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If separate capacitive height sensors are used, then the distance between chassis and axle can be determined, but the system cost increases

Engineering Contradiction:
Improvedistance measurementVSAvoidsystem cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The vehicle's own structural components (chassis and axle) serve as the sensing elements. Instead of requiring externally purchased and installed sensors, the system uses the vehicle's existing parts to perform the measurement function, making the system self-sufficient and eliminating additional cost centers

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Existing vehicle components are made multi-functional by enabling them to serve both their primary structural role and the secondary function of height sensing. This eliminates the need to purchase and install separate expensive sensors, directly reducing system cost while maintaining measurement precision

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 integration eliminates the need for separate sensors, simplifies the system, and effectively adjusts the vehicle's height by using existing components, enhancing operational efficiency and reducing costs.

Implementation Method 1

at least one capacitive height sensor is provided for the at least one axle by means of which the distance (D) between the chassis (1) and the at least one axle (2) can be determined, wherein the capacitive height sensor has a variable capacitance (C2), which forms the chassis (1) together with the at least one axle (2)

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3452311B1Air-suspended vehicle and method for electronic level control of an air-suspended vehicle
Publication Date: 2023.08.30 ZF CV SYST EURO BV
  • EP3452311B1 patent drawingFigure 1~5
  • EP3452311B1 patent drawingFigure 2~4

AI summary

The invention relates to an electronic level control device for an air-suspended vehicle, for example for an air-suspended trailer vehicle, having a chassis (1) with at least one axle (2), wherein at least two wheels (14) are arranged on the axle (2), wherein an air spring (3) for at least one of the wheels (14) is arranged between the axle (2) and the chassis (1), wherein an electronic control unit (6) can bring about a level control by actuating a magnetic valve (4), wherein the magnetic valve (4) can supply the at least one air spring (3) with compressed air from a compressed air store (5) or can release same from the air spring (3) into the atmosphere for level control, and wherein at least one capacitive height sensor is provided for the at least one axle (2), by means of which the distance (D) between the chassis (1) and the at least one axle (2) can be established. In order to simplify the distance measuring, according to the invention, the capacitive height sensor has a variable capacitance (C2) formed by the chassis (1) together with the at least one axle (2).