Variable Nozzle Device Wear Reduction via Curved Engagement

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Solution Overview

Problem

Existing variable nozzle devices for exhaust turbochargers face high wear at the engagement portion between the lever plate and the drive ring, which affects the stability and accuracy of the nozzle vane position over time, leading to reduced supercharging efficiency.

Innovation Solution

The design incorporates a lever plate with a linear portion and a drive ring with a protruding curved surface, where the turning radius of the drive ring is greater than the lever plate, reducing stress and friction at the contact area, and optimizing the shape to minimize clearance and friction drag, thereby reducing wear and maintaining accurate operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the lever plate and drive ring use conventional engagement surfaces, then the structure is simple, but wear at the engagement portion increases over time

Engineering Contradiction:

Improvewear resistanceVSAvoidengagement surface structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The drive ring engagement surface is designed with a protruding curved surface shape, and the lever plate engagement surface includes a roll surface that contacts the curved surface. This curved geometry reduces stress concentration and distributes contact forces more evenly, thereby reducing wear at the engagement portion while maintaining structural simplicity

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention changes the geometric parameters of the engagement surfaces by introducing specific curvature radii and surface profiles. The protruding curved surface on the drive ring and the corresponding roll surface on the lever plate create optimized contact conditions that reduce friction and wear, improving reliability without significantly complicating the device

Inventive Principle:

Principle #35Parameter changes

2Stress or pressure

If the drive ring has a larger turning radius than the lever plate, then stress at the contact area is reduced, but the device dimensions increase

Engineering Contradiction:

Improvecontact stressVSAvoiddrive ring turning radius

Core Design Contradiction:

Stress or pressureVSLength of moving object

Solution Approach 1:

By designing the drive ring with a protruding curved surface having an optimized radius of curvature that is larger than the lever plate's turning radius, the contact stress is distributed over a larger area. This curvature design reduces peak stresses at the engagement portion while the specific geometric relationships are optimized to control the overall device dimensions

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Measurement precision

If the engagement portion has minimal clearance, then position accuracy is improved, but friction drag increases

Engineering Contradiction:

Improvenozzle vane position accuracyVSAvoidfriction drag

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The protruding curved surface on the drive ring and the roll surface on the lever plate are designed with specific curvature radii that optimize the contact geometry. This curved surface design allows for minimal clearance between components while reducing friction drag through optimized contact conditions, thereby improving position accuracy without excessive energy loss

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 wear at the engagement portion, ensuring stable and accurate operation of the nozzle vane for a longer period, allowing for precise regulation of supercharge pressure in the engine.

Implementation Method 1

The first-side roll surface includes a lever-plate-side linear portion extending linearly in at least a part of a range which is to be in contact with the first-side guide surface. The first-side guide surface includes a drive-ring-side protruding curved surface portion extending in a protruding curve shape in at least a part of a range which is to be in contact with the first-side roll surface.

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11739655B2Variable nozzle device and variable-displacement type exhaust turbocharger

Publication Date: 2023.08.29 MITSUBISHI HEAVY IND ENGINE & TURBOCHARGER LTD

AI summary

A variable nozzle device includes: a nozzle mount; a plurality of nozzle vanes; a drive ring being having a plurality of receiving portions disposed at different positions along a circumferential direction; and a plurality of lever plates each having a fixed portion to be fixed to corresponding one of the plurality of nozzle vanes and an engaging portion to be engaged with corresponding one of the plurality of receiving portions of the drive ring. The receiving portions include a first-side guide surface and a second-side guide surface. The engaging portions each include a first-side roll surface which is to be in contact with the first-side guide surface and a second-side roll surface which is to be in contact with the second-side guide surface. The first-side roll surface includes a lever-plate-side linear portion extending linearly in at least a part of a range which is to be in contact with the first-side guide surface. The first-side guide surface includes a drive-ring-side protruding curved surface portion extending in a protruding curve shape in at least a part of a range which is to be in contact with the first-side roll surface.