Valve Clearance Adjustment via Cam Profile Measurement
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Solution Overview
Problem
Existing valve clearance adjustment methods for internal combustion engine mechanisms require multiple measurements of cam profiles and are sensitive to the tolerance of pitch dimensions in adjusting screws, making the process time-consuming and inaccurate.
Innovation Solution
A method that involves measuring the cam profile once to identify a specific rotation angle where a predetermined valve clearance is achieved, allowing the rocker arm to face the cam surface at that angle, and then adjusting the screw to set the clearance to zero using a lock nut, enabling accurate adjustment regardless of pitch dimension tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple cam profile measurements are performed to achieve accurate valve clearance adjustment, then the manufacturing precision is improved, but the loss of time increases
Solution Approach 1:
The cam profile is measured in advance to identify the specific rotation angle where the predetermined lift amount occurs. This preliminary measurement allows the adjustment process to proceed directly to the correct position without requiring multiple measurement cycles, thereby reducing adjustment time while maintaining precision.
Solution Approach 2:
The invention replaces the traditional iterative mechanical adjustment method with a method based on cam profile measurement and rotation angle identification. By using measurement data to determine the exact rotation angle, the system eliminates the need for repeated trial-and-error adjustments, reducing both time and measurement cycles.
2Ease of manufacture
If the pitch dimensions of the adjusting screw are within tolerance, then the ease of manufacture is improved, but the manufacturing precision of valve clearance adjustment deteriorates
Solution Approach 1:
The invention replaces reliance on the mechanical pitch dimensions of the adjusting screw with a measurement-based rotation angle identification system. By determining the correct rotation angle from cam profile measurements, the system achieves precise valve clearance adjustment independent of screw pitch tolerance, allowing easier manufacturing of the adjusting screw while maintaining adjustment precision.
Solution Approach 2:
The invention changes the control parameter from screw pitch dimensions to rotation angle based on cam profile measurements. This parameter change allows the system to achieve precise valve clearance adjustment without being sensitive to variations in screw pitch, thereby improving ease of manufacture while maintaining precision.
3Device complexity
If the adjusting screw is tightened until valve clearance reaches zero without using a thickness gauge, then the device complexity is reduced, but the manufacturing precision deteriorates
Solution Approach 1:
The invention replaces the need for thickness gauge tools with a measurement-based rotation angle identification system. By using cam profile measurements to determine the exact rotation angle for zero clearance, the system eliminates the need for additional measurement tools while maintaining high precision adjustment.
Data Source
AI summary
Provided is a valve clearance adjusting method by which an accurate valve clearance adjustment can be easily performed regardless of the tolerance of pitch dimensions of an adjusting screw. The valve clearance adjusting method including: measuring a cam profile of the camshaft 50 mounted on the cylinder head100; identifying, on the basis of a measurement result of the cam profile, a predetermined rotation angle θV of the camshaft 50 at which a predetermined lift amount corresponding to a predetermined valve clearance is obtained; rotating the camshaft 50 and allowing a pressed portion 61, 71 of the rocker arm 60, 70 to face a cam surface at the predetermined rotation angle θV; rotating an adjusting screw 90 with the pressed portion faced with the cam surface and setting a valve clearance to zero; and fastening the adjusting screw 90 with a lock nut 91.