Cam Angle Sensor Boss Stiffness via EGR Passage Integration
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Solution Overview
Problem
Conventional cam angle sensor attaching structures for internal combustion engines suffer from low surface stiffness at the attachment point, leading to vibrations that degrade the accuracy of detecting camshaft rotational angles.
Innovation Solution
The proposed structure includes a cylinder head with an EGR housing portion that integrates a tubular boss portion for attaching the cam angle sensor, connected to a high-stiffness EGR passage, enhancing the stiffness around the sensor attachment point to suppress vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cam angle sensor is attached to a flat point of the cylinder head cover, then the attachment is simple and accessible, but the surface stiffness is low causing sensor vibration and detection accuracy deterioration
Solution Approach 1:
The invention creates a localized stiffening structure (protruding portion) at the specific attachment point on the cylinder head cover, while the rest of the cover maintains its original design. This localized modification increases surface stiffness precisely where the sensor is mounted without requiring changes to the entire cover structure, thus resolving the contradiction between simple attachment and high measurement precision.
Solution Approach 2:
The invention transitions from a two-dimensional flat surface attachment to a three-dimensional protruding structure. By creating a protruding portion that extends from the flat surface of the cylinder head cover, the attachment point gains additional structural dimensionality, which significantly increases local stiffness and reduces vibration while maintaining attachment simplicity.
2Stability of the object's composition
If the cam angle sensor is attached to a flat surface with wide area, then the mounting is stable and accessible, but the surface stiffness is low leading to sensor vibration under engine vibration
Solution Approach 1:
Instead of making the entire cylinder head cover rigid (which would compromise mounting stability and increase complexity), the invention applies local quality enhancement by creating a protruding portion only at the sensor attachment location. This localized stiffening maintains the overall stability of the cover while providing the necessary surface stiffness to prevent sensor vibration.
3Measurement precision
If a stiffening structure is added to the cylinder head cover to reduce sensor vibration, then detection accuracy improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention minimizes device complexity by applying stiffening only where needed - a simple protruding portion at the sensor attachment point. This localized approach avoids the need for complex global reinforcement structures, maintaining manufacturing simplicity while achieving the goal of improved detection accuracy through reduced sensor vibration.
Solution Approach 2:
The protruding portion adds vertical dimensionality to the attachment surface, creating a stiffening effect through three-dimensional structure rather than requiring complex planar reinforcement. This dimensional approach achieves high stiffness with minimal added complexity, as the protruding geometry naturally provides structural rigidity without requiring additional components or complex assembly.
Data Source
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AI summary
[Problem to be Solved] It is to provide a cam angle sensor attaching structure for an internal combustion engine capable of enhancing stiffness around a point where a cam angle sensor is attached to suppress vibration of the cam angle sensor to thereby prevent accuracy of detecting a rotational angle of a camshaft from deteriorating. [Solution] An EGR housing portion 25 attached to a cylinder head 4 includes: an upper wall 25D with an attaching boss portion 28A, 28B to which a cam angle sensor 31, 32 is attached, the upper wall being connected to a front wall 25A, a rear wall 25B, and a left side wall 25C; and a tubular EGR passage portion 26 with an EGR passage 26a through which an EGR gas flows, the EGR passage portion being located on the same side as the left side wall 25C. The EGR passage portion 26 includes: an EGR gas inlet 26b provided at the front wall 25A, to introduce the EGR gas into the EGR passage 26a; and an EGR gas outlet 26c provided at the rear wall 25B, to discharge the EGR gas from the EGR passage 26a. The attaching boss portion 28A, 28B is connected to the EGR passage portion 26.