Swashplate Angle Sensor Linkage Spring Design
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Solution Overview
Problem
Existing swashplate angle sensors for variable displacement hydraulic units are complex, costly, and prone to inaccuracies due to machining tolerances and wear, making them difficult to install in existing hydraulic units without significant modifications.
Innovation Solution
A swashplate angle sensor design featuring a magnet carrier rotatable around a sensor axis, connected via a mechanical linkage element, such as a linkage spring, which transforms the circular arc motion of the swashplate's feedback link into a rotation of the magnet carrier, allowing for accurate angle measurement without requiring significant space or design changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetic sensors are mounted directly on the swashplate or displacement element, then angle measurement is achieved, but the sensor is subjected to high friction, wear, and machining tolerance inaccuracies
Solution Approach 1:
A feedback link serves as an intermediary mechanical element that transmits the angular position information from the swashplate to the sensor assembly. The feedback link is rotatably connected to the swashplate and carries a magnet, allowing the sensor to measure angle indirectly through this mediator rather than directly on the swashplate, thereby reducing wear and friction on the measurement components.
Solution Approach 2:
The sensor assembly is segmented into separate functional components: the feedback link (mechanical transmission element), the magnet carrier (magnet assembly), and the magnetic sensor (measurement element). This segmentation allows each component to be optimized independently and reduces the wear burden on any single component while maintaining measurement accuracy.
2Measurement precision
If complex sensor assemblies are used to achieve accurate angle measurement, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The complex mechanical sensing mechanisms (such as potentiometers, encoders, or mechanical linkages with multiple moving parts) are replaced with a simple magnetic field-based sensing system. A magnet mounted on the feedback link interacts with a magnetic sensor (e.g., Hall effect sensor or magnetoresistive sensor), eliminating the need for complex mechanical-to-electrical conversion mechanisms while achieving high measurement precision.
Solution Approach 2:
The feedback link serves multiple functions: it transmits hydraulic forces, indicates swashplate angular position, and carries the magnet for the sensor assembly. This multi-functionality reduces the need for separate dedicated sensing mechanisms, thereby simplifying the overall device complexity while maintaining accurate angle measurement capability.
3Measurement precision
If precision sensors are installed in existing hydraulic units, then measurement accuracy improves, but installation difficulty and cost increase due to required modifications
Solution Approach 1:
The feedback link is a pre-existing component in variable displacement hydraulic units that naturally indicates the angular position of the swashplate or displacement element. The invention utilizes this self-service feature by mounting the magnet and sensor assembly onto the existing feedback link structure, allowing the system to provide its own measurement reference without requiring external calibration or complex installation procedures.
Solution Approach 2:
The magnet and sensor assembly are nested onto the existing feedback link structure of the hydraulic unit. The feedback link acts as a carrier that already exists in the system, and the sensing components are integrated onto it, allowing the sensor assembly to be installed within the existing structural envelope without requiring major modifications to the hydraulic unit housing or architecture.
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 provides a simple, robust, and cost-effective angle sensor that compensates for wear and production tolerances, enabling accurate angle measurement and easy installation in existing hydraulic units, including those of the swashplate and bent axis construction types, with reduced friction and hysteresis effects.
Implementation Method 1
A magnet is mounted on a magnet carrier rotatable around a sensor axis, and a sensor for sensing the orientation of the magnet
Implementation Method 2
a sensor for sensing the orientation of the magnet
Data Source
AI summary
The invention is directed to a swashplate angle sensor (10) for a variable displacement hydraulic unit (1). The hydraulic unit (1) comprising a housing (2), within which a swashplate (3) with a rod shaped feedback-link (12) fixedly attached to the swashplate (3) is arranged pivotable around a swashplate axis (7). The angle sensor (10) comprising a magnet (16) mounted rotatable on a magnet carrier (13), and a sensor (15) for sensing the orientation of the magnet (16). The magnet carrier (13) is located in a control block (14) attached to the housing (2) and is located parallel to the feedback-link (12). The magnet carrier (13) is rotatable around a sensor axis (18) being parallel to the swashplate axis (7). A linkage spring (11) provides a connection between the feedback-link (12) and the magnet carrier (13) such that a pivoting of the swashplate (3) with the feedback-link (12) causes a rotation of the magnet carrier (13).