Variable Valve Actuation Roller Selection for Noise Reduction
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Solution Overview
Problem
Variable valve timing control devices with planetary gear drives suffer from increased clearance deviations due to manufacturing differences, leading to hammering noise and reduced control responsiveness due to alternating torque fluctuations.
Innovation Solution
A variable valve actuation apparatus using an electric motor with an eccentric rotation member, rolling elements, and a cage that allows radial displacement, where the rolling elements are selected based on measured clearance to maintain optimal meshing and reduce noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a planetary gear drive is used as a speed reducer, then the rotational speed of the output shaft can be reduced to control valve timing, but the clearance space dimension deviates from the allowable range due to manufacturing differences, causing hammering noise
Solution Approach 1:
The patent applies parameter changes by providing a plurality of rolling elements with different outside diameters and selecting the appropriate size based on the actual clearance measurement. This allows adjustment of the meshing parameters to compensate for manufacturing deviations, ensuring optimal clearance and preventing hammering noise while maintaining the speed reduction function.
Solution Approach 2:
The patent implements preliminary action by measuring the clearance space before final assembly and pre-selecting the appropriate rolling element size. This preliminary measurement and selection process ensures that the correct rolling elements are installed before the speed reducer is finalized, preventing clearance deviations and hammering noise from occurring during operation.
2Ease of operation
If a planetary gear drive is used as a speed reducer, then valve timing control is achieved, but alternating torque fluctuations cause hammering noise and reduced control responsiveness
Solution Approach 1:
The patent changes the physical parameter of the rolling elements by providing multiple size variants. By selecting and installing rolling elements with the appropriate outside diameter based on actual clearance measurements, the meshing characteristics are optimized to minimize alternating torque fluctuations and hammering noise, thereby reducing harmful factors while maintaining control functionality.
3Ease of manufacture
If standard rolling elements are installed without clearance measurement, then assembly is simplified, but clearance deviation exceeds allowable range causing operational issues
Solution Approach 1:
The patent applies preliminary action by measuring the clearance space before final assembly and pre-selecting the appropriate rolling element size. Although this adds a measurement step, it prevents operational failures and ensures reliable clearance within the allowable range, ultimately improving product reliability while maintaining reasonable manufacturing efficiency.
Solution Approach 2:
The patent enables parameter changes by providing rolling elements with different outside diameters. This allows the clearance parameter to be adjusted and optimized based on actual measurements, ensuring that the final assembly meets the required clearance specifications and maintains high reliability during operation.
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
The solution effectively suppresses hammering noise and enhances control responsiveness by ensuring precise clearance adjustments within a specific range, improving the operational stability and efficiency of the variable valve timing control device.
Implementation Method 1
an eccentric rotation member configured to rotate eccentrically with respect to a center of rotation of an output shaft of the electric motor by torque transmitted from the electric motor
Data Source
AI summary
In a variable valve actuation apparatus with a speed reducer between a timing sprocket and a camshaft for changing a phase of the camshaft relative to the sprocket, while reducing normal-rotation/reverse-rotation of an electric motor, the speed reducer includes an eccentric rotation member connected to an output shaft of the motor, an annular member connected to the sprocket, a plurality of rollers installed between an inner toothed portion of the annular member and an outer peripheral surface of the eccentric rotation member, and a cage connected to the camshaft for circumferentially partitioning the respective rollers, while permitting a radial displacement of each roller. Depending on a dimension of a clearance space between the eccentric rotation member and the annular member, a suitable one of a plurality of roller sets, each having a different outside diameter, is selected, and then the selected rollers are installed.