Crankshaft Counterweight Angular Offset Design

Solution Overview

Problem

The existing counterweight arrangement for crankshafts in internal combustion engines is difficult to manufacture and expensive due to its complexity.

Innovation Solution

A crankshaft design featuring pairs of counterweights angularly offset on each side of the front, rear, and central crankpins, reducing the number of counterweights required for balancing, which simplifies manufacturing and reduces costs while maintaining effective balance and torsional vibration control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional counterweight arrangement with counterweights attached to each crankshaft cheek is used, then engine balancing is achieved, but manufacturing difficulty and cost increase

Engineering Contradiction:

Improveengine balancingVSAvoidmanufacturing difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple counterweight functions into fewer, larger counterweight structures. Instead of having separate counterweights for each crankpin, the invention combines counterbalancing functions for multiple cylinders into integrated counterweight assemblies that span across multiple crankshaft cheeks, reducing the total number of discrete counterweight components and simplifying manufacturing.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The counterweights in the patent are designed to perform multiple balancing functions simultaneously. Each counterweight structure is configured to counterbalance forces from multiple crankpins and cylinders, making a single counterweight component serve universal balancing purposes for several engine components rather than being dedicated to a single crankpin.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If traditional counterweight arrangement with counterweights attached to each crankshaft cheek is used, then engine balancing is achieved, but manufacturing cost increases

Engineering Contradiction:

Improveengine balancingVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple counterweight functions into fewer, larger counterweight structures. Instead of having separate counterweights for each crankpin, the invention combines counterbalancing functions for multiple cylinders into integrated counterweight assemblies that span across multiple crankshaft cheeks, reducing the total number of discrete counterweight components and simplifying manufacturing.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The counterweights in the patent are designed to perform multiple balancing functions simultaneously. Each counterweight structure is configured to counterbalance forces from multiple crankpins and cylinders, making a single counterweight component serve universal balancing purposes for several engine components rather than being dedicated to a single crankpin.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If fewer counterweights are used, then manufacturing cost and complexity reduce, but engine balancing effectiveness may be compromised

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidengine balancing

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs asymmetric counterweight configurations where counterweights are positioned at specific non-uniform angular locations and have varying mass distributions. This asymmetric arrangement is carefully calculated to generate the precise balancing forces needed to counteract the asymmetric firing forces and inertial forces from multiple cylinders, maintaining balancing effectiveness despite using fewer counterweight components.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention changes the parameters of the counterweights including their angular positions, radial distances from the crankshaft center, and mass distributions. By optimizing these parameters, the fewer counterweights can generate sufficient balancing moments to counteract the unbalanced forces from all cylinders, achieving effective engine balancing with reduced component count.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9273604B2Crankshaft

Publication Date: 2016.03.01 PROGRESS RAIL LOCOMOTIVE INC

AI summary

A crankshaft having a front end, a rear end, and a central axis extending from the front end to the rear end is provided. The crankshaft includes a front crankpin, a rear crankpin, and one or more central crankpins. The front crankpin is located in proximity to the front end and the rear crankpin is located in proximity to the rear end. Further, the one or more central crankpins are located substantially equidistant from the front crank pin and the rear crankpin. The crankshaft further includes pairs of counterweights disposed on each side of the front crankpin, the rear crankpin and the one or more central crankpin. The counterweights are disposed such that counterweights in each pair of counterweights are angularly offset with respect to each other.