Variable Valve Mechanism Assembly with Enlarged Stem End
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Solution Overview
Problem
Existing variable valve mechanisms for internal combustion engines are complex to assemble and can apply stress to sensitive hydraulic components like lash adjusters during assembly.
Innovation Solution
A variable valve actuating device with a valve stem having an enlarged stem end and a second spring retainer engaged by a cotter, allowing for simple assembly by placing the valve lifter on top of the second valve retainer, and minimizing stress on the lash adjuster by using a switch member that moves under oil pressure between positions to control valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second valve spring is compressed via the valve lifter during assembly, then the valve spring can be installed, but the assembly work becomes highly complex and pressure is applied to sensitive hydraulic components
Solution Approach 1:
The valve stem is divided into two distinct sections: a first section with a first diameter for engaging the first spring retainer, and a second section with a second diameter for engaging the second spring retainer. This segmentation allows each spring to be installed independently through separate access points, eliminating the need to compress the second spring through the valve lifter and simplifying the assembly process.
Solution Approach 2:
The enlarged second section of the valve stem acts as an intermediary structure that provides a direct engagement point for the second spring retainer. This intermediary feature eliminates the need for complex assembly procedures by allowing the second spring to be installed through the second access hole without requiring compression via the valve lifter.
2Ease of manufacture
If pressure is applied during assembly to compress the second valve spring, then the spring can be installed, but stress is applied to sensitive hydraulic components such as the lash adjuster
Solution Approach 1:
The valve stem is segmented into two sections with different diameters, allowing the second spring to be installed through a separate second access hole. This segmentation enables the second spring to be compressed and installed independently, preventing the transmission of compressive forces to the lash adjuster and other sensitive hydraulic components.
Solution Approach 2:
The second section of the valve stem with its enlarged diameter serves as an intermediary that provides a dedicated path for second spring installation. This intermediary structure isolates the compression forces to the spring installation area, protecting the lash adjuster from harmful stresses during assembly.
3Device complexity
If the valve stem has a uniform diameter throughout, then the structure is simpler, but the valve lifter cannot be easily positioned and assembled
Solution Approach 1:
The valve stem incorporates local quality variations by having a first section with a first diameter and a second section with a second diameter. The second section is specifically enlarged to provide a localized engagement feature for the second spring retainer, enabling easy positioning and assembly of the valve lifter while maintaining overall structural integrity.
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
Facilitates easy assembly of the valve actuating device without stressing the lash adjuster and enhances durability and precision in valve operation by ensuring the valve lifter applies pressure only to the cotter, reducing wear and maintaining positional accuracy.
Implementation Method 1
a switch member (53) received in the valve lifter so as to be selectively movable under oil pressure between a first position where the switch member abuts the end surface of the valve stem
Implementation Method 2
a first spring retainer (36) attached to an intermediate part of the valve stem to interpose a first valve spring (35) surrounding the valve stem between the first spring retainer and a part of the cylinder head
Data Source
AI summary
The variable valve actuating device (20) comprises a switch pin (53) slidably received in the valve lifter (24) so as to selectively abut the end surface of the valve stem as the valve lifter is actuated by the cam. The device further comprises a first spring retainer (36) attached to an intermediate part of the valve stem (32) to engage a first valve spring (35), and a second spring retainer (44) slidably engaged by an end part of the valve stem to engage a second valve spring (43). The valve stem is provided with a stem end (39) which is enlarged with respect to a part of the valve stem slidably engaging the second spring retainer so as to define a shoulder surface (40a) that engages the second spring retainer against a spring force of the second valve spring.