Valvetrain Cylinder Deactivation Two-Stroke Engine Braking
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Solution Overview
Problem
Existing valvetrain systems struggle to combine two-stroke and four-stroke actuation techniques on the same valves, limiting the implementation of variable valve actuation (VVA) methods for engine braking and cylinder deactivation.
Innovation Solution
A valvetrain configuration that enables two-stroke engine braking, late intake valve closing, and cylinder deactivation on a single cylinder, using lost motion springs and capsules to switch between normal and specialized lift profiles for intake and exhaust valves, allowing for provisioning of VVA techniques on all or some cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable valve actuation hardware is distributed across three cylinders and six valve pairings to implement multiple actuation techniques, then the system can provide two-stroke and four-stroke actuation techniques, but the device complexity and hardware requirements increase significantly
Solution Approach 1:
The patent divides the valvetrain into separate intake and exhaust sides, with each side having dedicated rocker arms and variable valve actuation hardware. This segmentation allows independent control of intake and exhaust valves, enabling implementation of multiple actuation techniques (two-stroke, four-stroke, cylinder deactivation) on a single cylinder without requiring hardware distribution across multiple cylinders.
Solution Approach 2:
The valvetrain design makes the single cylinder valvetrain universal by incorporating hardware that can perform multiple functions: two-stroke actuation, four-stroke actuation, and cylinder deactivation. The intake and exhaust rocker arms with their respective variable valve actuation capabilities enable the same hardware to support different operating modes, eliminating the need to distribute specialized hardware across three cylinders.
2Ease of operation
If normal valve lift profiles are used on all intake and exhaust valves, then the valvetrain operates in standard four-stroke mode, but the system cannot achieve two-stroke engine braking or cylinder deactivation functionality
Solution Approach 1:
The valvetrain employs dynamic valve lift profiles that can change based on operating conditions. The system switches between normal four-stroke lift profiles and specialized profiles (two-stroke engine braking profiles, cylinder deactivation profiles) using variable valve actuation hardware. This dynamic adaptability allows the same hardware to achieve both standard operation and specialized functions without compromising ease of operation.
3Adaptability or versatility
If specialized lift profiles are implemented on all valves, then two-stroke and cylinder deactivation functions are enabled, but the device complexity and control requirements increase
Solution Approach 1:
The patent applies specialized lift profiles selectively to specific valves based on local requirements. For example, during two-stroke engine braking, the exhaust valve receives a specialized engine braking lift profile while the intake valve may use a different profile. During cylinder deactivation, only the exhaust valve receives the deactivation profile. This localized application of specialized profiles reduces control complexity compared to applying specialized profiles to all valves simultaneously.
Data Source
AI summary
A method for engine braking on a type III valvetrain diesel engine comprises, on a first downstroke of a reciprocating piston, deactivating a normal intake lift profile on a first intake valve to implement a deactivated intake profile. Before a first upstroke of the reciprocating piston completes, a late intake valve closing lift profile is actuating on a second intake valve and beginning an engine brake lift profile on a first exhaust valve. On a second downstroke of the reciprocating piston, the engine brake lift profile on the first exhaust valve is completing and a normal exhaust lift profile is deactivating on a second exhaust valve to implement a deactivated exhaust profile on the second exhaust valve. Before a second upstroke of the reciprocating piston completes, a second engine brake lift profile is beginning on the first exhaust valve.