Translational Swivel Angle Sensing for Axial Piston Machines

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Solution Overview

Problem

Existing rotary swivel angle measuring devices in hydrostatic axial piston machines require significant design space and are prone to jamming due to the radial movement of the return lever, and translational devices have limited measuring ranges.

Innovation Solution

A translational swivel angle measuring device with a Hall sensor and rod-shaped permanent magnets that detect the swivel angle indirectly by moving along the adjustment piston's direction, eliminating radial movements and increasing the measuring range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a rotary swivel angle measuring device is used with radial movement of the return lever, then the swivel angle can be detected, but the design space requirement increases and the risk of jamming increases

Engineering Contradiction:

Improveswivel angle detectionVSAvoiddesign space

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent replaces the rotary mechanical encoding system with a translational measurement system using a linear encoder and magnet. The return lever's rotary motion is substituted by a translational movement along the adjustment piston's axis, eliminating the need for radial movement and complex rotary couplings. This substitution reduces the design space while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of converting linear adjustment piston movement into rotary encoder movement (as in prior art), the patent inverts the approach by using a translational encoder that moves linearly along with the adjustment piston. This inversion eliminates the radial in-and-out movement of the return lever, reducing jamming risk and design space requirements.

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If a rotary swivel angle measuring device with return lever is used, then the swivel angle can be detected, but the risk of jamming increases due to radial movement

Engineering Contradiction:

Improveswivel angle detectionVSAvoidjamming risk

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical return lever system with a magnetic field-based translational measurement system. The return lever's mechanical radial movement is substituted by a magnet moving translationally along the adjustment piston, detected by a linear encoder. This eliminates the jamming-prone radial movement while maintaining detection reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnet as an intermediary between the adjustment piston and the encoder system. Instead of direct mechanical coupling with radial movement, the magnet's translational position along the piston axis is detected by the linear encoder, eliminating the jamming risk associated with radial lever movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the measuring range of the swivel angle measuring device is increased, then more swivel angles can be detected, but the design space requirement increases

Engineering Contradiction:

Improvemeasuring rangeVSAvoiddesign space

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent employs a dynamic translational measurement system where the encoder moves along with the adjustment piston rather than remaining stationary. This dynamic configuration allows the measuring range to expand with the piston's travel distance without requiring additional design space, as the measurement system scales with the mechanical components.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The translational encoder and magnet system serves multiple functions: it measures swivel angle across the full range of piston travel, eliminates the need for separate rotary mechanisms, and reduces design space requirements. This multi-functionality allows increased measuring range without proportional increase in design space.

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 solution reduces the risk of jamming and increases the measuring range by up to 60 mm, optimizing space utilization and enhancing the swivel angle detection efficiency.

Implementation Method 1

A translational swivel angle measuring device with a Hall sensor and rod-shaped permanent magnets that detect the swivel angle indirectly

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS20250362157A1Swivel Angle Measuring Device on a Hydrostatic Axial Piston Machine with Variable Stroke Volume

Publication Date: 2025.11.27 ROBERT BOSCH GMBH

AI summary

A swivel angle measuring device is configured to indirectly sense a swivel angle of a swashplate or cylinder drum of an axial piston machine. The swivel angle is adjustable using an adjustment piston guided in an adjustment cylinder. The swivel angle measuring device includes a movable encoder and a transducer affixed to a housing. The encoder is formed by two permanent magnets that are carried linearly and translationally by the adjustment piston along its direction of movement and that have a distance to one other.