Curved-Vent Piston Retainer Plate for Stress and Fuel Pressure Relief

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Solution Overview

Problem

Bent-axis fuel variable displacement piston pumps experience localized contact stress and high fuel pressure due to the sphere-on-plate wear interface between the piston and the piston retainer plate, leading to potential damage and trapped fuel.

Innovation Solution

A piston retainer plate with a curved vent integrated into the curved annular surface to maximize contact area and provide controlled venting, reducing localized stress and pressure, and allowing for lubrication and fuel flow management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sphere-on-plate wear interface is used between the piston and piston retainer plate, then the piston can be held and guided effectively, but localized contact stress and high fuel pressure occur leading to potential damage

Engineering Contradiction:

Improvepiston retention and guidanceVSAvoidlocalized contact stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent introduces a curved annular surface with a curved vent that matches the curvature of the piston sphere. This curved geometry distributes the contact stress across a larger area of the spherical piston surface, preventing localized stress concentration that would occur with a flat plate interface. The curved vent specifically positioned at the region of greatest contact maximizes stress distribution while maintaining effective piston retention and guidance.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Productivity

If the piston moves rapidly on a bent axis, then productivity increases, but fuel becomes trapped leading to hydrolock conditions

Engineering Contradiction:

Improvepiston speedVSAvoidtrapped fuel causing hydrolock

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful trapped fuel from the piston pocket by introducing a curved vent that provides a dedicated escape path. The vent is strategically positioned and shaped to allow fuel to be expelled from the piston pocket during rapid piston movement, preventing hydrolock conditions while maintaining high productivity. The curved geometry of the vent aligns with the piston motion to maximize fuel evacuation efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

3Stress or pressure

If the contact area between piston and retainer plate is increased, then localized stress is reduced, but the device complexity increases

Engineering Contradiction:

Improvecontact stress distributionVSAvoidretainer plate structure

Core Design Contradiction:

Stress or pressureVSDevice complexity

Solution Approach 1:

The curved annular surface serves multiple functions simultaneously: it provides the venting passage for fuel evacuation, it creates the curved contact surface that distributes stress, and it maintains the structural integrity of the retainer plate. This multi-functional design achieves reduced localized stress through increased effective contact area without proportionally increasing device complexity, as the same geometric feature performs multiple critical functions.

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

The curved vent reduces wear and pressure, preventing hydrolock and enabling larger, faster piston assemblies by optimizing the contact interface and venting fuel effectively.

Implementation Method 1

The curved vent is configured to receive fuel from within the piston pocket when the piston is moving toward the curved annular surface and release fuel into the piston pocket when the piston is moving away from the curved annular surface

Methodology Applied

Scientific EffectFuel venting:

Implementation Method 2

the curved vent that extends into the curved annular surface that defines the piston pocket to decrease localized contact stress between the piston and the piston retainer plate

Methodology Applied

Scientific EffectContact stress reduction:

Implementation Method 3

allowing for lubrication and fuel flow management... venting fuel effectively... preventing hydrolock

Methodology Applied

Scientific EffectFuel escape/venting:

Data Source

PatentUS12372074B1Piston retainer plate

Publication Date: 2025.07.29 HAMILTON SUNDSTRAND CORP

AI summary

A piston retainer plate includes a first end, a second end opposite the first end, a piston pocket extending from the first end to the second end, a straight annular surface extending from the first end, an angled annular surface extending at an angle from the second end, a curved annular surface connected to the straight annular surface and the angled annular surface, the curved annular surface being between the straight annular surface and the angled annular surface, and a curved vent within the curved annular surface. The straight annular surface, the angled annular surface, and the curved annular surface define the piston pocket.