Radial Fluid Device Piston Timing Control

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Solution Overview

Problem

Radial fluid devices face challenges in varying fluid flow without increasing piston stroke displacement distance or energy consumption, particularly in designs with high piston diameter to stroke ratios, which require significant force to move cams and often result in inefficient energy use and vibration.

Innovation Solution

A radial fluid device design featuring a cylinder block with paired radially extending cylinders and pistons, where the stroke timing of one piston is adjustable relative to another, allowing for fluid flow adjustment without varying displacement distance, using mechanically linked cams to reduce energy requirements and minimize vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If piston stroke displacement distance is increased to adjust fluid flow, then fluid flow is improved, but device complexity and energy consumption increase

Engineering Contradiction:
Improvefluid flowVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent changes the timing parameter (phase angle) between pistons rather than changing piston displacement distance. By adjusting when pistons begin their strokes relative to each other, fluid flow is controlled without modifying the physical displacement distance, thus avoiding increased device complexity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamically adjustable piston timing through phase adjustment mechanisms that allow the phase angle between pistons to be changed during operation. This dynamic timing control enables fluid flow adjustment without mechanical redesign or complex structural modifications

Inventive Principle:
Principle #15Dynamics

2Productivity

If cam offset is increased to vary displacement, then fluid flow adjustment is improved, but force required to move cam increases significantly

Engineering Contradiction:
Improvefluid flow adjustmentVSAvoidforce to move cam
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

Instead of changing cam offset (which requires large forces), the patent changes the timing parameter (phase angle) between pistons. This parameter substitution allows fluid flow control through temporal coordination rather than spatial displacement, dramatically reducing the force required for adjustment

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If piston diameter to stroke ratio is increased, then device compactness is improved, but force required to move cam increases

Engineering Contradiction:
Improvedevice compactnessVSAvoidforce to move cam
Core Design Contradiction:
Volume of moving objectVSForce

Solution Approach 1:

The patent decouples fluid flow control from cam displacement by using piston timing (phase angle) as the control parameter. This allows compact high ratio pistons to be used without requiring large cam offsets, as the timing adjustment doesn't depend on cam displacement magnitude

Inventive Principle:
Principle #35Parameter changes

4Use of energy by moving object

If piston timing is adjusted to control fluid flow, then energy consumption is reduced, but device complexity increases

Engineering Contradiction:
Improveenergy consumptionVSAvoiddevice complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent uses simple phase angle timing adjustments between pistons to control fluid flow, replacing energy-intensive mechanical displacement methods. The timing mechanism uses minimal energy compared to moving heavy cams or changing piston displacement, achieving energy efficiency with acceptable complexity

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2679817B1Variable radial fluid device with differential piston control
Publication Date: 2016.11.09 BELL HELICOPTER TEXTRON INC
  • EP2679817B1 patent drawingFigure 1
  • EP2679817B1 patent drawingFigure 2A~2B
  • EP2679817B1 patent drawingFigure 3A~3B

AI summary

According to one embodiment, a radial fluid device (300) comprises a cylinder block (320), a first plurality of pistons (340a-340f) including a first piston, and a second plurality of pistons (340a'-340f') including a second piston. Each of the first plurality of pistons (340a-340f) are slidably received within a different one of a first plurality of radially extending cylinders. Each of the second plurality of pistons (340a'-340f') are slidably received within a different one of a second plurality of radially extending cylinders. The second piston is configurable to begin its stroke at a different time relative to the first piston within the first cylinder pair.