Valve Spring Retainer Skirt Design for Cylinder Head Size Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional internal combustion engines face challenges in reducing the size of the cylinder head while maintaining sufficient valve lift and minimizing wear on the cam and rocker arm, especially when the roller is movable relative to the rocker arm.

Innovation Solution

A valve spring retainer design featuring a cylindrical portion with a constant outer diameter, a cone-shaped portion with increasing inner diameter, and a flange portion, which allows for a compact configuration that avoids interference with the roller and rocker arm, enabling reduced cylinder head size and sufficient valve lift without relocating the rocker arm or valve spring retainer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the roller is made movable relative to the rocker arm to enable variable valve operation, then valve operation switching capability is improved, but the roller moves closer to the valve spring retainer causing potential interference

Engineering Contradiction:

Improvevariable valve operation capabilityVSAvoidinterference between roller and valve spring retainer

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The valve spring retainer transitions from a conventional cylindrical shape to a skirt-like shape that extends axially beyond the roller's movement range. This dimensional extension in the axial direction creates sufficient clearance space without requiring radial displacement, thereby preventing interference while accommodating the movable roller mechanism for variable valve operation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The valve spring retainer is segmented into distinct functional zones: a skirt-like portion that provides clearance space for the movable roller, a valve installation portion that maintains sealing functionality, and a spring support portion that provides structural stability. This segmentation allows each zone to independently fulfill its specific function without interfering with others.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If the position of the rocker arm is moved away from the valve spring retainer to avoid interference, then interference is avoided, but the size of the cylinder head increases

Engineering Contradiction:

Improveinterference avoidanceVSAvoidcylinder head size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

Instead of moving the rocker arm radially away from the valve spring retainer (which would increase cylinder head size), the valve spring retainer is extended axially in the direction of valve movement. This creates clearance space in the axial dimension, allowing the rocker arm to remain in its original radial position while still avoiding interference with the movable roller.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Object-affected harmful factors

If the position of the valve spring retainer is moved away from the rocker arm to avoid interference, then interference is avoided, but the valve lift amount becomes insufficient

Engineering Contradiction:

Improveinterference avoidanceVSAvoidvalve lift amount

Core Design Contradiction:

Object-affected harmful factorsVSLength of moving object

Solution Approach 1:

The valve spring retainer is extended axially beyond the roller's movement range, creating clearance space in the axial dimension. This allows the valve spring retainer to maintain its original radial position relative to the rocker arm, ensuring sufficient valve lift, while simultaneously providing the necessary clearance to avoid interference with the movable roller through axial extension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Object-affected harmful factors

If the valve spring retainer is given a skirt-like shape to avoid interference, then interference is avoided, but the manufacturing complexity increases

Engineering Contradiction:

Improveinterference avoidanceVSAvoidvalve spring retainer manufacturing

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The valve spring retainer is divided into functionally distinct segments: a skirt-like portion for clearance, a valve installation portion for sealing, and a spring support portion for structural integrity. This segmentation allows each portion to be optimized independently for its specific function, simplifying the manufacturing process while achieving the complex overall geometry needed to avoid interference.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11193403B2Valve spring retainer and internal combustion engine

Publication Date: 2021.12.07 YAMAHA MOTOR CO LTD

AI summary

An internal combustion engine switches valve operation states, reduces or prevents wear of a cam and a rocker arm, and reduces the size of the cylinder head to ensure a sufficient valve lift amount. A valve spring retainer includes a cylindrical portion including a first through hole with an inner diameter decreases from the first end portion toward the second end portion, a cone-shaped portion including a second through hole with an inner diameter increases as it extends away from the second end portion of the cylindrical portion, and a flange portion extending radially outward from the cone-shaped portion. An outer diameter of the cylindrical portion is constant from the first end portion to the second end portion, and an outer diameter of the cone-shaped portion increases as it extends away from the second end portion.