Magnetic Swivel Angle Sensing for Compact Axial Piston Machines

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing rotary swivel angle measuring devices for hydrostatic axial piston machines require significant installation space and are prone to jamming due to the radial movement of the return lever, especially at the end areas of the adjustment piston travel, leading to reduced measuring accuracy and increased risk of mechanical failure.

Innovation Solution

A translational swivel angle measuring device with two or more permanent magnets is used, where the encoder is coupled to the adjustment piston and moves in translation, minimizing the overall length and reducing the need for radial movements, while maintaining high measuring accuracy through a holistic design that optimizes the measuring range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a rotary swivel angle measuring device with a return lever is used, then the swivel angle can be detected, but the installation space requirement increases and the device is prone to jamming

Engineering Contradiction:

Improveswivel angle detection accuracyVSAvoidinstallation space and mechanical complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical return lever system with a magnetic field-based encoding system. Permanent magnets mounted on the adjustment piston create magnetic fields that are detected by a Hall sensor, eliminating the need for mechanical return levers and their associated wear-prone contact points. This substitution reduces installation space and eliminates jamming risks while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces permanent magnets as an intermediary between the adjustment piston and the Hall sensor. These magnets convert the linear position of the adjustment piston into magnetic field variations that the Hall sensor can detect, enabling indirect measurement without direct mechanical coupling. This intermediary approach simplifies the transmission mechanism and reduces the risk of mechanical failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the return lever moves radially to engage with the adjustment piston recess, then the encoder can be driven, but the risk of jamming increases at the end areas of piston travel

Engineering Contradiction:

Improvemeasuring rangeVSAvoidrisk of jamming

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent eliminates the radial movement of the return lever by using magnetic fields to transmit information. The permanent magnets move with the adjustment piston, and their magnetic field signatures are detected by the Hall sensor, removing the need for mechanical engagement and radial movement that causes jamming at end positions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of using mechanical contact to transmit motion from the adjustment piston to the encoder, the patent inverts the approach by using magnetic fields to transmit position information. The permanent magnets are moved by the adjustment piston, and their magnetic field variations are detected indirectly by the Hall sensor, eliminating direct mechanical coupling and its associated reliability issues.

Inventive Principle:

Principle #13The other way round (Inversion)

3Measurement precision

If the bearing and holder require increased installation space in the axial direction, then the encoder can be properly supported, but the overall length of the device increases

Engineering Contradiction:

Improveencoder support stabilityVSAvoidaxial installation space

Core Design Contradiction:

Measurement precisionVSLength of moving object

Solution Approach 1:

The patent replaces the mechanical bearing and holder system with a magnetic field-based detection system. The Hall sensor detects the position of permanent magnets through magnetic field interactions, eliminating the need for extensive mechanical support structures in the axial direction. This substitution significantly reduces the axial installation space while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 minimizes installation space and reduces the risk of jamming, allowing for a wide measuring range with high accuracy and efficient conversion of adjustment piston movement into encoder movement, particularly in hydrostatic axial piston machines with swashplate or inclined axis designs.

Implementation Method 1

a transducer affixed to the housing, in particular a Hall sensor

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS20250361862A1Swivel Angle Measuring Device on a Hydrostatic Axial Piston Machine with Variable Stroke Volume

Publication Date: 2025.11.27 ROBERT BOSCH GMBH

AI summary

In a translational swivel angle measuring device designed and configured to indirectly sense a swivel angle of a swashplate or cylinder drum of an axial piston machine, the swivel angle being adjustable by an adjustment piston guided in an adjustment cylinder, the swivel angle measuring device includes a movable encoder and a transducer affixed to the housing. The encoder is formed by two permanent magnets, for example, that may be carried linearly and translationally by the adjustment piston along its movement direction.