Engine Braking via Cylinder Flow-Through Path

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Solution Overview

Problem

Existing engine braking technologies are costly due to the need for complex valve actuation systems and variable geometry turbochargers, and there is a need to economically improve and optimize engine braking power.

Innovation Solution

A method and system for engine braking that involves opening intake and exhaust valves in a first cylinder to create a flow-through path from the intake manifold to the exhaust manifold, charging a second cylinder with air through this path, and using the charged second cylinder to brake the engine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If complex valve actuation systems and variable geometry turbochargers are used to improve engine braking power, then braking power is improved, but system cost and complexity increase

Engineering Contradiction:

Improveengine braking powerVSAvoidvalve actuation system complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The engine cylinders are segmented into different functional roles within the same engine cycle. Some cylinders operate in normal power mode while others are dedicated to braking events. This segmentation allows the engine to achieve enhanced braking power through coordinated cylinder operations without requiring complex external braking systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The engine implements periodic braking events where cylinders alternately switch between power generation and braking modes. The valve actuation system periodically changes timing patterns to create controlled braking events, allowing the engine to deliver enhanced braking power in pulses rather than continuously, which reduces the need for constantly complex control systems.

Inventive Principle:

Principle #19Periodic action

2Power

If complex valve actuation systems and variable geometry turbochargers are used to improve engine braking power, then braking power is improved, but manufacturing cost increases

Engineering Contradiction:

Improveengine braking powerVSAvoidmanufacturing cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The engine cylinders serve multiple functions - they can operate in normal power mode or switch to dedicated braking mode depending on operational requirements. The same physical cylinders and basic valve actuation infrastructure are used for both power generation and braking, eliminating the need for separate dedicated braking components and reducing manufacturing costs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The engine uses its own existing infrastructure (cylinders, pistons, basic valve actuation system, intake and exhaust manifolds) to generate braking power rather than requiring external braking components. The engine essentially services its own braking needs through internal combustion processes, reducing the need for additional manufactured parts.

Inventive Principle:

Principle #25Self-service

3Device complexity

If traditional engine braking methods are used, then system simplicity is maintained, but braking power is insufficient

Engineering Contradiction:

Improvesystem simplicityVSAvoidbraking power

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The valve actuation system preliminarily prepares cylinders for braking events by adjusting valve timing patterns in advance. Intake valves are opened earlier and closed later to maximize air charging, and exhaust valves are timed to optimize pressure differentials. This preliminary preparation of the air charge and valve timing enables the engine to generate higher braking power when the braking event occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes operational parameters of the engine cylinders dynamically. Cylinders switch between normal power mode parameters and braking mode parameters, including different valve timing patterns, air charging strategies, and exhaust pressure management. These parameter changes allow the same physical system to deliver enhanced braking power without permanent structural modifications.

Inventive Principle:

Principle #35Parameter changes

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 approach enhances engine braking power by allowing two braking events per engine cycle, improves efficiency by using a fixed geometry turbine, and reduces costs compared to traditional systems.

Implementation Method 1

opening both an intake valve and an exhaust valve for a first cylinder in an engine to establish a flow-through path from an intake manifold to an exhaust manifold, and opening an exhaust valve for a second cylinder in an engine a first time to charge the second cylinder with air fed through the flow-through path

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS12234781B1Engine braking strategy using cylinder flow-through path for optimizing braking power

Publication Date: 2025.02.25 CATERPILLAR INC

AI summary

Operating an engine includes opening and closing exhaust valves in an engine braking timing pattern, charging a first cylinder with air fed directly from an intake manifold, and releasing the directly fed air in a first braking event. Operating the engine further includes charging the first cylinder with air fed via a flow-through path through a second cylinder operating as an air conduit, and releasing the air fed through the flow-through path and pressurized to brake the engine in a second braking event. Related apparatus and valve lift profiles are also disclosed.