Pressure-Balanced Gaseous Fuel Dosing Valve With Bellows Compensation

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Solution Overview

Problem

Existing metering valves for gaseous fuels struggle to compensate for pneumatic closing forces caused by pressure differences, leading to inefficiencies and increased costs in actuator design.

Innovation Solution

A metering valve design featuring a plate-shaped valve seat element with a corrugated bellows that creates a compensation chamber, equalizing gas pressure to generate a counterforce that cancels out pneumatic forces, allowing for efficient and secure operation with reduced opening force and increased switchable pressure differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional metering valve design is used without pressure compensation, then the actuator design is simpler, but the valve cannot compensate for pneumatic closing forces resulting from pressure differences

Engineering Contradiction:
Improvepressure compensation capabilityVSAvoidactuator design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The valve body is divided into distinct pressure chambers (inlet pressure chamber and outlet pressure chamber) separated by a partition wall. This segmentation allows independent pressure management in different zones, enabling the outlet pressure to act on the closing element to compensate for pneumatic closing forces without complicating the overall actuator design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a pressure balance by allowing the outlet pressure to act on the closing element through the compensation chamber, equalizing the pressure forces on both sides of the closing element. This equipotential approach compensates for pneumatic closing forces while maintaining a relatively simple actuator design.

Inventive Principle:
Principle #12Equipotentiality

2Measurement precision

If the valve stroke is made independent of pressure conditions through pressure balancing, then metering precision is improved, but the device complexity increases

Engineering Contradiction:
Improvefuel metering precisionVSAvoidpressure balancing structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The valve body is segmented into inlet and outlet pressure chambers with a partition wall, allowing the outlet pressure to be channeled to act on the closing element. This segmentation enables pressure-balanced operation that ensures precise fuel metering independent of pressure conditions while keeping the structure manageable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A compensation chamber serves as an intermediary structure that transmits the outlet pressure to the closing element. This mediator allows the pressure balancing function to be achieved without directly complicating the actuator design, as the compensation chamber acts as an intermediate pressure transmission path.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Area of stationary object

If larger valve assemblies are realized with standard magnets, then the valve size or pressure differential capability is increased, but the actuator design becomes more complex

Engineering Contradiction:
Improvevalve assembly sizeVSAvoidactuator design complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

By implementing pressure balancing that equalizes forces on the closing element, the patent enables larger valve assemblies to be actuated by standard magnets. The pressure compensation reduces the net force the magnet must overcome, allowing larger valve areas or higher pressure differentials without requiring oversized actuators.

Inventive Principle:
Principle #12Equipotentiality

Solution Approach 2:

The outlet pressure acting on the closing element through the compensation chamber creates a counterforce that opposes the pneumatic closing forces. This counterweight effect allows standard magnets to adequately actuate larger valve assemblies by reducing the net opening force required.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

4Force

If the compensation chamber is arranged on the side of the closing element facing the valve seat element, then the counterforce is optimized, but the valve stroke space is reduced

Engineering Contradiction:
Improvecounterforce optimizationVSAvoidvalve stroke space
Core Design Contradiction:
ForceVSLength of moving object

Solution Approach 1:

The compensation chamber is arranged in the radial direction rather than extending axially, utilizing the radial space around the closing element. This dimensional change allows the compensation chamber to be positioned optimally for counterforce generation without significantly reducing the axial valve stroke space.

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

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 results in a compact, cost-effective actuator concept that maintains secure closure and efficient operation, enabling larger valve assemblies or higher pressure differences with standard magnets, and potentially eliminates the need for return springs.

Implementation Method 1

The compensation chamber is connected to a pressure chamber via a recess formed in the closing element, so that the same gas pressure prevails in both chambers regardless of the switching position of the metering valve

Methodology Applied
Scientific EffectPressure equalization: Pascal's Law

Implementation Method 2

When the gas pressure in the pressure chamber increases, the gas pressure in the compensation chamber also increases. This results in a pneumatic pressure force acting directly or indirectly on the closing element, which – due to the position of the compensation chamber – acts in the opening direction

Methodology Applied
Scientific EffectPneumatic pressure force: Pressure Gradient

Data Source

PatentEP3658764B1Dosing valve for a gaseous fuel
Publication Date: 2021.05.05 ROBERT BOSCH GMBH
  • EP3658764B1 patent drawingFigure 1
  • EP3658764B1 patent drawingFigure 2
  • EP3658764B1 patent drawingFigure 3a~3b

AI summary

The invention relates to a metering valve (1) for a gaseous medium, in particular for a gaseous fuel, comprising a preferably planar valve seat element (2) having at least one flow-through opening (3) for the gaseous medium, a closing element (4) movable in a stroke-like manner and interacting in a sealing manner with the valve seat element (2) in order to release and close the at least one flow-through opening (3), and a corrugated or folding bellows (5) connected to the closing element (4) for delimiting a compensation space (6), which is connected to a pressure space (8) via a recess (7) formed in the closing element (4) so that the same gas pressure prevails in both spaces (6, 8) irrespective of the switched position of the metering valve (1). According to the invention, the compensation space (6) is arranged on the side of the closing element (4) facing the valve seat element (2) and is delimited in the axial direction by a pressure surface (10) which is formed on the closing element (4) or on a component (11) connected to the closing element (4), in particular a flange component.