Valve Timing Control Apparatus Backlash Reduction
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Solution Overview
Problem
Conventional valve timing control apparatuses face challenges in accurately adjusting the gap between rollers and inner teeth, leading to torque variation and strong impact sounds due to limited precision in roller diameters, which deteriorates the quality of the apparatus.
Innovation Solution
The apparatus includes a deceleration mechanism with an eccentric rotational shaft, a bearing portion, and a pressing member, such as a leaf spring, to adjust the power transmission bodies radially and reduce backlash, using a recess portion on the eccentric rotational shaft and a bearing portion to press the power transmission bodies against the inner teeth, thereby reducing impact sounds and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rollers with different outer diameters are selectively assembled to adjust the gap, then the gap can be adjusted, but the precision is limited and impact sound occurs
Solution Approach 1:
The patent changes the parameter of the pressing member (using a leaf spring with elastic properties) to dynamically adjust and maintain the gap between the roller and inner teeth, eliminating the need for multiple rollers with different diameters and achieving precise gap control without impact sound
Solution Approach 2:
The patent introduces a dynamic pressing mechanism using a leaf spring that can adaptively adjust the gap between the roller and inner teeth during operation, replacing the static approach of selectively assembling rollers with different fixed diameters
2Adaptability or versatility
If multiple rollers with different diameters are prepared and selectively assembled, then gap adjustment is possible, but device complexity increases
Solution Approach 1:
The patent makes the pressing member (leaf spring) serve multiple functions: it presses the roller against the inner teeth to eliminate backlash, adjusts the gap dynamically, and maintains operational responsiveness, replacing the need for multiple specialized rollers with different diameters
Solution Approach 2:
The patent uses a single roller with fixed diameter combined with a deformable pressing member (leaf spring) whose contact pressure can change, achieving the adaptability of multiple rollers while simplifying the device to a single standardized roller assembly
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 effectively suppresses impact sounds and improves the quality of the valve timing control by reducing backlash and maintaining operational responsiveness, while also simplifying the assembly process and reducing production costs by eliminating the need for rollers with different diameters.
Implementation Method 1
a pressing member that allows the power transmission body to generate power in a tooth bottom surface direction of the inner tooth through the bearing portion may be disposed at the recess portion. The pressing member may include a leaf spring bent in a circular arc shape.
Data Source
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AI summary
A valve timing control apparatus of an internal combustion engine may include a driving rotational body to which torque is transmitted from a crankshaft, a driven rotational body fixed to a camshaft to which torque is transmitted from the driving rotational body, an electric motor disposed between the driving rotational body and the driven rotational body and relatively rotating the driving rotational body and the driven rotational body when electric power is applied thereto, and a deceleration mechanism that decelerates a rotational speed of the electrical motor and transmit the decelerated rotational speed to the driven rotational body.