Variable Displacement Piston Sensor Integration
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Solution Overview
Problem
Conventional variable displacement piston machines are complex and costly due to the need for additional components and linkages to sense the swash plate inclination, leading to potential faults in signal transmission and increased sensitivity to errors.
Innovation Solution
A sensor element is integrated into the auxiliary cylinder, using a RF signal to induce a current in the plunger, allowing for reliable and cost-effective displacement sensing without additional linkages, utilizing an antenna and electronic circuit to determine the swash plate angle and piston displacement based on impedance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensing piston with potentiometer is used to sense swash plate inclination, then displacement sensing is achieved, but device complexity increases and reliability decreases due to additional linkages and signal transmission components
Solution Approach 1:
The sensing function is merged with the existing plunger structure. The plunger serves both its original function of tilting the swash plate and as the sensing element for displacement measurement. The sensor element is integrated into the auxiliary cylinder housing, eliminating the need for separate sensing components and their associated linkages.
Solution Approach 2:
The sensing function is extracted from the main piston mechanism and implemented through a separate sensor element that detects plunger position directly. This allows the sensing system to operate independently without requiring mechanical linkages to the swash plate or main piston, simplifying the overall structure.
2Measurement precision
If additional linkages and draw bars are used to connect swash plate to sensor, then displacement can be measured, but reliability decreases due to potential faults in signal transmission
Solution Approach 1:
The mechanical linkage system (draw bars, tension rods) is replaced with a direct sensor element that detects plunger position through non-contact or minimal-contact means. The sensor element measures displacement directly from plunger movement, eliminating mechanical signal transmission components that are prone to faults.
3Measurement precision
If conventional sensing methods with separate components are used, then displacement sensing is possible, but manufacturing cost increases
Solution Approach 1:
The sensing function is combined with existing components (plunger and auxiliary cylinder), eliminating the need for separate sensing housings, mounting structures, and linkage mechanisms. This integration reduces part count and assembly complexity, leading to lower manufacturing costs.
Solution Approach 2:
The plunger is given dual functionality: it performs its original role in tilting the swash plate and simultaneously serves as the sensing element for displacement measurement. This multi-functionality eliminates the need for dedicated sensing components, reducing overall system cost.
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
This solution simplifies displacement sensing, enhances reliability, and reduces costs by eliminating the need for complex linkages, while maintaining accuracy in determining piston displacement within the variable displacement axial piston machine.
Implementation Method 1
The plunger may e.g. comprise an electrically conductive material, e.g. iron or aluminum, which enables induction of a current, and wherein movement is sensed based on change of impedance by induction in the plunger as it moves in the auxiliary cylinder. The auxiliary cylinder may, for this purpose, include an antenna which transmits a radio frequency (RF) signal which provides induction of a current in the plunger.
Data Source
AI summary
A variable displacement axial piston machine. The variable displacement axial piston machine includes a cylinder block with at least one main cylinder and main piston, a swash plate, a plunger arrangement with a plunger and auxiliary cylinder, and a sensor. The swash plate is arranged to effect movement of the main piston in the main cylinder upon rotation of the swash plate relative to the cylinder arrangement. The plunger is arranged to tilt the swash plate relative to the cylinder arrangement and to control a stroke of the main cylinder in the main piston. To provide a simple and reliable measurement of displacement of the main piston in the main cylinder, the invention provides a sensor element which is fixed in the auxiliary cylinder and which is adapted to sense movement of the plunger therein.