Horizontally-Opposed Engine Crankshaft Angular Velocity Detection
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Solution Overview
Problem
In internal combustion engines with a horizontally-opposed cylinder arrangement, precise detection of crankshaft angular velocity is hindered by the large run-out of the crankshaft, which affects the accuracy of angular velocity detection due to the generator's position at the shaft end.
Innovation Solution
A detection sensor is positioned on the crankcase, facing the trajectory of a to-be-detected body integrated with the crankshaft, allowing for precise angular velocity measurement while avoiding electromagnetic interference and protecting the sensor from external debris, with the sensor mounted externally to prevent dimension and weight increases in the engine casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the generator is disposed at the shaft end of the crankshaft to detect angular velocity, then the detection function is achieved, but the run-out of the crankshaft becomes large and detection precision deteriorates
Solution Approach 1:
A to-be-detected body (pulser ring) is introduced as an intermediary component between the crankshaft and the detection sensor. This pulser ring rotates with the crankshaft and provides a stable reference surface for the detection sensor, thereby eliminating the effect of crankshaft run-out on detection precision while maintaining the generator's position at the shaft end.
2Reliability
If the detection sensor is mounted externally on the crankcase, then the sensor is protected from external debris and electromagnetic interference, but the device complexity increases due to additional mounting structures
Solution Approach 1:
The detection sensor is integrated into the crankcase structure by forming a through-hole in the crankcase and mounting the sensor within this hole. This merging of the sensor with the crankcase structure provides protection from external debris and electromagnetic interference while avoiding the need for separate external mounting brackets or housings, thus reducing overall device complexity.
3Adaptability or versatility
If the crankshaft length is increased to accommodate more cylinders in horizontally-opposed arrangement, then the cylinder count increases, but the run-out of the crankshaft increases and detection precision deteriorates
Solution Approach 1:
The to-be-detected body (pulser ring) serves as a mediator that rotates with the crankshaft and provides a stable reference for the detection sensor. This intermediary component decouples the detection function from the crankshaft's physical run-out, allowing the crankshaft length to be extended for more cylinders without compromising detection precision.
4Measurement precision
If the to-be-detected body is integrated with the crankshaft, then the detection function is achieved, but the manufacturing precision requirements increase due to the integration
Solution Approach 1:
The to-be-detected body (pulser ring) is designed as a separate component that can be independently manufactured and then attached to the crankshaft. This segmentation allows each component to be manufactured with standard precision tolerances, and the assembly process ensures proper alignment, thereby reducing the overall manufacturing precision requirements compared to creating a fully integrated one-piece structure.
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 configuration enables high-precision detection of crankshaft angular velocity, protects the sensor from damage, and maintains engine design integrity by avoiding unnecessary changes or increased dimensions, while suppressing vibration and flexure in the crankshaft, ensuring accurate measurements even with increased cylinder count and crankshaft length.
Implementation Method 1
The extremity of an eddy current type microdisplacement sensor (detection sensor) opposes an outer peripheral face of the ring gear. The microdisplacement sensor detects a crank angle.
Data Source
AI summary
An internal combustion engine includes a crankcase that defines a crank chamber, a crankshaft that has a crank housed in the crank chamber and is rotatably supported on the crankcase, a cylinder block that is joined to the crankcase and defines a plurality of cylinders in a horizontally-opposed arrangement, a to-be-detected body that rotates integrally with the crankshaft, and a detection sensor that extends through the crankcase from an upper face of the crankcase, is made to face a trajectory of the to-be-detected body, and generates a pulse signal in response to movement of the to-be-detected body. Thus, in a so-called horizontally-opposed internal combustion engine, a structure for disposing a detection sensor that can detect the angular velocity of a crankshaft with high precision is provided.