Pressure Reducer Diaphragm Assembly for Leak-Free Long Stroke

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing pressure reducers face issues with leakage due to axial movement of piston rods, leading to reduced functional accuracy and high manufacturing costs, particularly with roll and flat diaphragm designs that require larger diameters and are expensive to produce.

Innovation Solution

A pressure reducer assembly featuring a diaphragm made of silicone with a central hole diameter less than the piston rod's outer diameter, allowing for radial stress-induced deformation and increased stroke length, and a cost-effective stamping process for production, along with a diaphragm support surface to prevent slippage and a stop surface to manage spring force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a radial lip seal like diaphragm is used in pressure reducers, then pressure control function is provided, but axial movement of the piston rod causes grooves to form in the sealing surface over time resulting in leakage

Engineering Contradiction:
Improvesealing performanceVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent employs a flexible diaphragm made of elastic material (such as rubber or polymer) that acts as both the sealing element and the piston rod. This flexible membrane can deform elastically to maintain sealing contact without forming permanent grooves, thereby resolving the contradiction between maintaining sealing performance and extending service life under axial movement conditions

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If roll diaphragm technology is used, then leakage is prevented, but larger diameters are required requiring more installation space and manufacturing cost increases

Engineering Contradiction:
Improvesealing performanceVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The flexible diaphragm design allows for a more compact configuration compared to rigid roll diaphragms. The elastic material can conform to the sealing surface and maintain effective sealing with a smaller diameter, thus preventing leakage while reducing installation space requirements

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the material parameters by using elastic materials with appropriate durometer and tensile properties, allowing the diaphragm to achieve effective sealing at smaller dimensions compared to traditional rigid roll diaphragm designs

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If flat diaphragms reinforced with fabric insert are used, then manufacturing cost is reduced, but the stroke is very low (up to 2mm) as the flat diaphragm is not stretchable

Engineering Contradiction:
Improvemanufacturing costVSAvoidstroke length
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The patent uses a flexible diaphragm made of elastic material without fabric reinforcement, allowing for greater stretchability and stroke length. The elastic material can deform significantly more than fabric-reinforced flat diaphragms, achieving stroke lengths exceeding 2mm while remaining cost-effective through simple stamping or molding processes

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent optimizes the thickness and material composition parameters of the diaphragm to achieve an balance between flexibility (for increased stroke) and structural integrity. By controlling the elastic material properties and diaphragm geometry, the design achieves extended stroke length without requiring expensive fabric reinforcement

Inventive Principle:
Principle #35Parameter changes

4Length of moving object

If the outer diameter of the piston rod is made greater than the diameter of the central hole of the diaphragm, then the diaphragm can be assembled over the piston rod with radial stress-induced deformation increasing stroke length, but assembly complexity increases

Engineering Contradiction:
Improvestroke lengthVSAvoidassembly complexity
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent designs the diaphragm with a central hole diameter slightly larger than the piston rod outer diameter in the unstressed state, allowing the diaphragm to be pre-assembled over the piston rod before operational radial stress is applied. This preliminary assembly action simplifies the assembly process while still achieving the desired radial stress-induced deformation and increased stroke length during operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent carefully selects the dimensional parameters (diaphragm hole diameter, piston rod diameter, diaphragm thickness) and material properties to ensure that the radial stress during normal operation produces the desired deformation and stroke extension without requiring complex assembly procedures or special tools

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 enhances the stroke length of the diaphragm, improves the durability and cost-effectiveness of the pressure reducer, reduces maintenance needs, and prevents leakage, while maintaining functional accuracy over time.

Implementation Method 1

the diaphragm is adapted to be operatively coupled with the piston rod... the outer diameter of the piston rod is greater than the diameter of the central hole of the diaphragm and the diaphragm is assembled over the piston rod so that the central axis of the piston rod coincides with the central axis of the diaphragm

Methodology Applied
Scientific EffectRadial stress-induced deformation: Elasticity

Data Source

PatentEP4305501B1Pressure reducer
Publication Date: 2024.05.08 HUSQVARNA AB
  • EP4305501B1 patent drawingFigure 1
  • EP4305501B1 patent drawingFigure 2A~2B
  • EP4305501B1 patent drawingFigure 3A~3B

AI summary

A pressure reducer assembly (100) includes a pressure reducer body (110) defining at least one pressure reducer chamber (120) along a central axis (X-X'). The pressure reducer chamber (120) includes an inlet section (122) and an outlet section (124) fluidly coupled with the inlet section (122). The pressure reducer assembly (100) further includes a spring-operated hollow piston rod (121) having a center (X) along the central axis (X-X'), a cylindrical inner peripheral surface comprising an inner diameter (A), and a cylindrical outer peripheral surface comprising an outer diameter (B). A diaphragm (128) made of elastic material is adapted to be operatively coupled with the piston rod (121). The diaphragm (128) includes a central hole (150) having a center (Y) along a central axis (W-W') and a diameter (C). The pressure reducer assembly (100) is characterized in that, in an unmounted state, the outer diameter (B) of the piston rod (121) is greater than the diameter (C) of the central hole (150) of the diaphragm (128), whereas in a mounted state, the outer diameter (B) of the piston rod (121) is the same as the diameter (C) of the central hole (150) of the diaphragm (128), and the diaphragm (128) is assembled over the piston rod (121) so that the central axis (X- X') of the piston rod (121) coincides with the central axis (W-W') of the diaphragm (128).