Cylinder Block Crank Cap Layout for Lower Bearing Friction

Solution Overview

Problem

In internal combustion engines, the deformation of crankshafts under load leads to increased friction between crank journals and bearings, resulting in elevated friction loss, which existing machining methods to alleviate this issue increase manufacturing costs and time.

Innovation Solution

A cylinder block assembly design featuring crank caps with strategically removed parts, such as holes and grooves, allows for easier deformation under load, reducing friction loss without increasing manufacturing costs or time, by differentiating intermediate and side crank caps in terms of deformation ease.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If crank caps are machined to form holes and grooves to make them easier to deform when receiving a load from the crankshaft, then friction loss is reduced, but manufacturing costs and manufacturing time increase

Engineering Contradiction:

Improvefriction lossVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The invention applies local quality by making only the intermediate crank caps (second and third crank caps) easier to deform through hole formation, while the side crank caps (first and fourth crank caps) maintain their original solid structure. This localized modification reduces friction loss at the intermediate positions where deformation is most beneficial, without incurring the manufacturing costs of modifying all crank caps.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention implements partial action by forming holes in only two out of four crank caps (the intermediate ones), rather than modifying all crank caps. This partial modification is sufficient to achieve the desired friction reduction effect while minimizing manufacturing complexity and cost.

Inventive Principle:

Principle #16Partial or excessive action

2Loss of energy

If crank caps are machined to form holes and grooves to make them easier to deform when receiving a load from the crankshaft, then friction loss is reduced, but manufacturing time increases

Engineering Contradiction:

Improvefriction lossVSAvoidmanufacturing time

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The invention applies local quality by making only the intermediate crank caps (second and third crank caps) easier to deform through hole formation, while the side crank caps (first and fourth crank caps) maintain their original solid structure. This localized modification reduces friction loss at the intermediate positions where deformation is most beneficial, without incurring the manufacturing costs of modifying all crank caps.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention implements partial action by forming holes in only two out of four crank caps (the intermediate ones), rather than modifying all crank caps. This partial modification is sufficient to achieve the desired friction reduction effect while minimizing manufacturing complexity and time.

Inventive Principle:

Principle #16Partial or excessive action

3Loss of energy

If intermediate crank caps are made with removed parts to deform more easily, then friction loss between crank journals and bearings is reduced, but device complexity increases

Engineering Contradiction:

Improvefriction lossVSAvoidcrank cap structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The invention applies local quality by making only the intermediate crank caps (second and third crank caps) easier to deform through hole formation, while the side crank caps (first and fourth crank caps) maintain their original solid structure. This localized modification reduces friction loss at the intermediate positions where deformation is most beneficial, without incurring the manufacturing costs of modifying all crank caps.

Inventive Principle:

Principle #3Local quality

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 design effectively reduces friction loss between crank journals and bearings while maintaining cost-effectiveness and manufacturing efficiency by selectively incorporating hole parts and grooves in the crank caps to accommodate load deformation.

Implementation Method 1

the intermediate crank caps are configured to have shapes including removed parts which are removed compared with side crank caps so as to more easily deform when receiving a load from the crankshaft

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11300073B2Cylinder block assembly

Publication Date: 2022.04.12 TOYOTA JIDOSHA KK

AI summary

A cylinder block assembly has: a cylinder block having three cylinders aligned side-by-side; and four crank caps arranged side-by-side in an alignment direction of the cylinders and fastened to the cylinder block. The crank caps and the cylinder block are provided with crank bearings which rotatably support a crankshaft. The crank caps are arranged at both sides of each cylinder in the alignment direction. Intermediate crank caps positioned at intermediate positions in the plurality of the crank caps include removed parts so as to more easily deform when receiving a load from the crankshaft compared with the side crank caps.