Spring-Loaded Encoder Wheel for Crankshaft Speed Sensing
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Solution Overview
Problem
Existing engine speed sensor systems face challenges in accurately measuring rotational speed and position in limited spaces where traditional encoder wheels with magnetized ferrite cannot be effectively mounted due to space constraints and the need for precise alignment.
Innovation Solution
A load generating encoder wheel assembly featuring an annular support ring with a radially inwardly extending portion that compresses spring-like between a crankshaft and flywheel, allowing for flexible angular positioning of encoder material to generate a magnetic flux perpendicular to the sensor, enabling accurate speed and position measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional encoder wheel with magnetized ferrite is mounted on the crankshaft, then accurate rotational speed and position measurement can be achieved, but the available space on the crankshaft is limited and precise alignment is difficult to achieve
Solution Approach 1:
The encoder wheel is divided into two functional parts: the support ring (which provides mechanical mounting and spring loading) and the encoder material (which contains the magnetic poles). This segmentation allows the encoder material to be optimally positioned for measurement accuracy while the support ring adapts to the limited crankshaft space.
Solution Approach 2:
The encoder wheel assembly is nested within the existing crankshaft-flywheel structure. The support ring fits within the limited radial and axial space, with the encoder material nested on the outer circumference, maximizing space utilization while maintaining measurement precision.
2Measurement precision
If a traditional encoder wheel is mounted on the crankshaft, then speed sensing can be provided, but precise alignment is difficult to achieve in limited spaces
Solution Approach 1:
The spring-loaded support ring automatically self-aligns with the crankshaft and flywheel during assembly. The elastic deformation of the radially inwardly extending portion provides self-centering action, eliminating the need for precise manual alignment while ensuring accurate positioning of the encoder material relative to the sensor.
Solution Approach 2:
The support ring utilizes elastic deformation (change in shape parameter) to accommodate misalignment. By allowing the radially inwardly extending portion to flex within elastic limits, the system compensates for alignment variations and maintains precise encoder-sensor positioning without requiring strict alignment during installation.
3Strength
If the encoder wheel is compressed between the flywheel and crankshaft end, then secure mounting is achieved, but the encoder material positioning must be extremely precise
Solution Approach 1:
The support ring transitions from a rigid structure to a dynamic, spring-loaded component. The radially inwardly extending portion is designed to elastically deform under compression, providing mounting security through spring force while maintaining encoder material positioning through the inherent elasticity and recovery of the material, reducing the need for extreme manufacturing precision.
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 design allows for precise rotational speed and position measurement while accommodating space limitations, ensuring accurate misfire detection and compatibility with various shaft designs, including camshafts and crankshafts.
Implementation Method 1
The radially inwardly extending portion is compressed between the flywheel and the end of the shaft in spring-like fashion
Implementation Method 2
The encoder wheel typically includes an outer surface having magnetized ferrite therein. The ferrite can be magnetized to form alternating north and south poles around the circumference of the encoder wheel
Implementation Method 3
As the encoder wheel rotates, a magnetic sensor measures the change in the magnetic field of the alternating poles. From this alternating magnetic field, the rotational speed of the encoder wheel may then be calculated
Data Source
AI summary
A shaft assembly, includes an elongated shaft and a flywheel mounted to an end of the shaft. An encoder is mounted to the shaft and includes an annular support ring having a radially inwardly extending portion and an axially extending portion extending from a radially outer end of the radially inwardly extending portion. The radially inwardly extending portion defines a spring section which is compressed between the flywheel and the end of the shaft, and an encoder material is disposed on the axially extending portion of the annular support ring.