Adjustable Angle Sensor for Hydraulic Pump Displacement Control

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Solution Overview

Problem

Hydraulic axial displacement machines face challenges in maintaining consistent volumetric displacement and flow rates during forward and reverse operations due to variations in swashplate angular positions, which are not adequately addressed by existing feedback systems.

Innovation Solution

A control system with a feedback assembly that provides proportional feedback information to the swashplate position, including a valve arrangement, pivot arm, and adjustable angle sensor, allowing for balanced forward and reverse flow control characteristics, ensuring consistent flow rates regardless of operational direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an angle sensor is used to sense swashplate position, then feedback control precision is improved, but internal biasing or spring loading in the sensor compromises balancing and centering of the pivot arm

Engineering Contradiction:

Improveswashplate position sensing accuracyVSAvoidbalancing and centering of pivot arm

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent removes the angle sensor from the pivot arm assembly, extracting the sensing function entirely from the mechanical feedback mechanism. The sensor is positioned separately to detect pivot arm angle without physically interfering with the balancing springs or centering mechanism, thus eliminating the conflict between measurement precision and mechanical reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a separate mechanical feedback linkage that connects the pivot arm to the control valve without requiring the angle sensor to be mounted on the pivot arm itself. This intermediary linkage transmits positional information mechanically while allowing the sensor to remain externally mounted, preserving both sensing accuracy and mechanical balance

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the control system uses electro-proportional displacement control, then control precision is improved, but the system becomes vulnerable to angle sensor failure

Engineering Contradiction:

Improvedisplacement control precisionVSAvoidsystem operation continuity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent incorporates a mechanical feedback mechanism through the pivot arm that provides passive, spring-loaded centering and balancing forces. This mechanical backup exists beforehand and automatically maintains system equilibrium even when the electro-proportional control or angle sensor fails, cushioning against complete system failure

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent allows the control system to operate in multiple modes by changing the dominance of control parameters: normally electro-proportional control provides precision, but when sensor failure is detected, the system transitions to relying on the mechanical feedback parameter (spring-loaded pivot arm centering) to maintain basic operational reliability

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the pivot axis position is fixed, then manufacturing simplicity is improved, but forward and reverse flow control characteristics cannot be balanced

Engineering Contradiction:

Improvepivot axis positioning simplicityVSAvoidflow control symmetry

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent makes the pivot axis position adjustable rather than fixed, allowing the system to dynamically adapt its mechanical configuration. The pivot arm can be repositioned along the servo piston rod to achieve optimal forward and reverse flow balance, transforming a static manufacturing constraint into a dynamic adjustment capability

Inventive Principle:

Principle #15Dynamics

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 system ensures balanced flow rates in both forward and reverse operations by adjusting the pivot axis and angle sensor, allowing the control system to maintain desired swashplate positions, even if the angle sensor fails, through mechanical feedback without internal biasing, thus enhancing operational reliability and efficiency.

Implementation Method 1

an angle sensor for sensing the angular position of the pivot arm

Methodology Applied

Scientific EffectAngular sensing:

Implementation Method 2

providing hydraulic pressure to move one or more servo-pistons along their movement axis

Methodology Applied

Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 3

movement of the servo-piston(s) is transmitted to a swashplate, causing the angle of the swashplate to change

Methodology Applied

Scientific EffectMechanical transmission: Mechanical Force

Data Source

PatentUS11608825B2Displacement control with angle sensor adjustment

Publication Date: 2023.03.21 DANFOSS AS

AI summary

Control systems and feedback assemblies for hydraulic axial displacement machines, such as pumps and motors. The control systems and feedback assemblies can have enhanced adjustability. An angle sensor for sensing the angular position of a pivot arm can have a housing, and the housing can be angularly adjustable about the pivot axis relative to the pivot arm.