Fluid Supply Device Freezing Protection via Valve Venting

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Solution Overview

Problem

Devices used to supply aqueous urea solutions to SCR systems face issues with freezing, leading to equipment damage due to water expansion, and existing solutions like elastic compensating volumes are expensive and require significant design effort.

Innovation Solution

A device utilizing a displacement pump with a metal bellows displacement element and a valve arrangement that allows for complete aeration of the pump when not in use, preventing freezing by venting the fluid to the environment and ensuring the pump operates as a liquid pump when resumed, along with a fluid filter for contamination prevention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If elastic expansion volumes are provided to protect against freezing, then freezing damage is prevented, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:

Improvefreezing protectionVSAvoiddesign effort

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the freezing protection function from the fluid circuit by providing a separate venting path to the environment. Instead of protecting the fluid in-place, the system vents the fluid out during shutdown, removing the freezing hazard entirely from the pump and circuit.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The venting mechanism is activated automatically during shutdown sequence, performing the freezing protection action before the pump stops operating. The controller initiates the venting process in advance to ensure no freezing fluid remains in the pump when it stops.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the pump is vented to the environment during shutdown, then freezing damage is prevented, but fluid loss occurs

Engineering Contradiction:

Improvefreezing protectionVSAvoidfluid loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The system performs a partial venting action during shutdown, venting only the remaining fluid in the pump after normal operation. This is sufficient to prevent freezing without requiring complete evacuation of the entire fluid system, thereby minimizing fluid loss while achieving the freezing protection goal.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If a metal bellows displacement element is used, then sealing problems are avoided, but manufacturing cost increases

Engineering Contradiction:

Improvesealing performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical seals with a metal bellows displacement element that uses elastic deformation to create a seal. The bellows flexes to accommodate fluid displacement while maintaining a seal against the pump housing, eliminating the need for complex mechanical seal assemblies.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The metal bellows utilizes changes in its physical state (elastic deformation) to create an effective seal. The bellows expands and contracts in response to pressure changes, maintaining sealing contact without requiring rigid mechanical seal components that wear or leak over time.

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 freezing damage and ensures a reliable, contamination-free fluid supply, reducing production and operational costs while maintaining system safety under frosty conditions.

Implementation Method 1

the pump is a positive displacement pump, wherein a displacement element is formed by a metal bellows in the form of a bellows that encloses a fluid chamber within the pump housing

Methodology Applied

Scientific EffectPositive displacement:

Implementation Method 2

the pump is completely or fully vented via a flow path to the environment, created by the valve arrangement, when the supply to the consumer is interrupted

Methodology Applied

Scientific EffectAeration: Aeration

Implementation Method 3

a line branch containing a throttling point and a valve arrangement are provided in the fluid circuit

Methodology Applied

Scientific EffectThrottling:

Data Source

PatentEP3710697B1Device for providing fluids under a specifiable pressure

Publication Date: 2021.10.06 HYDAC ELECTRONICS GMBH

Figure 1
Figure 2~3
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AI summary

The invention relates to a device for providing fluids under a specifiable pressure for the pressure supply of a consumer, such as a working unit (1) of an SCR (selective catalytic reduction) system for treating the exhaust gas of internal combustion engines, comprising at least one pump (3), which, in a fluid circuit (4) formed between a fluid reservoir (5) and the consumer (1), draws the fluid in question from the fluid reservoir (5) and feeds said fluid to the consumer (1). Said device is characterized in that a line branch (9), which contains a throttle point (18), and a valve assembly (23, 59, 61, 63) are provided in the fluid circuit (4), which valve assembly can be actuated into a switching position connecting the fluid reservoir (5) to the pump (3), in which switching position a flow path containing the line branch (9) having the throttle point (18) is formed, and which valve assembly can be actuated into a second switching position interrupting the supply of the consumer, in which second switching position a flow path connecting the pump (3) to the surroundings (57) is formed.