Safety Drain Valve Heating Element for Compressed Air Systems

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Solution Overview

Problem

The compressed air supply system in vehicles faces issues with ice formation at the drain valve during regeneration cycles, leading to potential blockages and disruptions, especially with clutch compressors, due to backflowing air expanding and cooling, which can cause condensation or ice crystals, affecting energy efficiency and system functionality.

Innovation Solution

A safety drain valve with a heating element coupled to the vehicle's ignition via a temperature switch, activated below a cut-in temperature to prevent freezing and deactivated above a switch-off temperature, ensuring energy efficiency and preventing ice formation, along with a 3/2-way valve design for controlled regeneration and a pressure switch for detecting control pressure and timing adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the drain valve is opened to allow regeneration air to flow outside, then the service life of filter devices is increased, but ice crystals may form and block the drain valve

Engineering Contradiction:
Improveservice life of filter devicesVSAvoiddrain valve functionality
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The heating element is activated before and during the regeneration process to prevent ice crystal formation proactively. The temperature switch detects when temperatures approach freezing point and activates the heating element in advance to counteract the cooling effect of expanding backflowing air, thereby preventing blockages before they occur.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The heating element acts as an intermediary between the temperature switch and the drain valve system. It provides thermal energy to the backflowing air and surrounding components, preventing the phase change of moisture into ice crystals that would block the valve, thus mediating between the cold backflowing air and the valve components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the heating element is activated continuously to prevent freezing, then ice formation is prevented, but energy consumption increases

Engineering Contradiction:
Improvedrain valve functionalityVSAvoidenergy consumption of heating element
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The heating element operates periodically rather than continuously, controlled by the temperature switch that activates it only when temperatures approach the freezing point and deactivates it when sufficient heat is generated. This periodic operation prevents ice formation while minimizing unnecessary energy consumption during warm periods.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The temperature switch provides feedback control for the heating element. It continuously monitors the temperature in the area of the valve seat and backflowing air, activating the heating element when temperatures approach freezing and deactivating it when the temperature rises above the switch-off temperature, thereby optimizing energy usage based on actual thermal conditions.

Inventive Principle:
Principle #23Feedback

3Stress or pressure

If backflowing air expands at the discharge valve, then pressure is reduced, but temperature drops causing condensation or ice crystals

Engineering Contradiction:
Improveair pressureVSAvoidair temperature
Core Design Contradiction:
Stress or pressureVSTemperature

Solution Approach 1:

The heating element changes the thermal parameter of the backflowing air by providing heat energy. This counteracts the temperature drop caused by adiabatic expansion, maintaining the temperature above the freezing point of moisture and preventing ice crystal formation while still allowing pressure reduction for proper drainage.

Inventive Principle:
Principle #35Parameter changes

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 effectively prevents ice formation and ensures continuous operation by maintaining the safety drain valve's functionality, enhancing energy efficiency and reducing the risk of blockages, while allowing for targeted regeneration and moisture flushing, thus ensuring reliable compressed air supply.

Implementation Method 1

a heating element (18) being arranged in the area of a valve seat (16) of the safety release valve (10)

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The heating element is activated by the temperature switch below a cut-in temperature T 1 below which the safety drain valve could freeze up

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

the backflowing air expands at the discharge valve, with the air and its immediate surroundings being cooled

Methodology Applied
Scientific EffectAdiabatic cooling: Adiabatic Cooling

Data Source

PatentEP2098429B1Safety discharge valve in compressed air supply plant for vehicles and method to operate such a compressed air supply plant
Publication Date: 2011.03.02 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP2098429B1 patent drawingFigure 1
  • EP2098429B1 patent drawingFigure 2
  • EP2098429B1 patent drawingFigure 3

AI summary

The safety drain valve (10) comprises a heating element (18), which is arranged in an area of a valve seat (16) of the safety drain valve. The heating element is coupled on an ignition (22) of the vehicle by a temperature switch (20). The safety drain valve is arranged in a supply line (28) connecting a compressor (24) and an air filter (26). Independent claims are included for the following: (1) a compressed air supply system for a vehicle; and (2) a method for operating a compressed air supply system.