Variable Camshaft Engine Valve Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Internal combustion engines, particularly diesel engines, face inefficiencies due to the limitations of fixed valve control times, which can lead to collisions and suboptimal gas exchange, resulting in reduced efficiency and increased emissions.
Innovation Solution
The implementation of a mixed camshaft system with a variable camshaft adjuster allows for adjustable valve control times, specifically a late opening of the exhaust valve and matching intake valve control times, optimizing the expansion stroke and compression efficiency, while avoiding piston collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exhaust valve opening time is advanced to improve gas exchange, then the piston collision risk increases, but if it is delayed to avoid collision, then the expansion stroke utilization decreases
Solution Approach 1:
The patent applies variable valve timing technology where the exhaust valve opening timing is dynamically adjusted based on operating conditions. The adjustable camshaft allows the exhaust valve to open at different crankshaft angles (between 0° and 25° before BDC) depending on load and speed, optimizing both collision avoidance and expansion stroke utilization across different operating ranges.
2Productivity
If the intake valve closing time is retarded to improve Miller cycle efficiency, then the cylinder filling decreases, but if it is advanced to maintain filling, then the compression efficiency reduces
Solution Approach 1:
The patent implements variable intake valve timing where the intake valve closing point is dynamically adjusted. By retarding the intake valve closing time (delaying closure), the patent achieves Miller cycle benefits with improved expansion stroke utilization while the adjustable timing ensures adequate cylinder filling is maintained through optimized valve events.
3Adaptability or versatility
If fixed valve timing is used to simplify control, then adaptability to different operating conditions decreases, but if variable valve timing is implemented, then device complexity increases
Solution Approach 1:
The patent employs variable camshaft timing mechanisms with adjustable camshafts that can be rotated to different positions using adjustment devices. This allows the valve timing to be adapted to different operating conditions (load, speed) while maintaining a relatively simple mechanical implementation through camshaft rotation rather than complex electronic control systems.
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 enhances engine efficiency by allowing better use of the piston expansion stroke, improving heating of the catalytic converter, optimizing compression, and reducing emissions, leading to increased engine power and efficiency across various operating conditions.
Implementation Method 1
a charge exchange stroke, which comprises an exhaust stroke and an intake stroke
Implementation Method 2
a power stroke, which comprises a compression stroke and a power stroke
Implementation Method 3
an internal combustion engine, in particular a diesel internal combustion engine
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The engine has working cylinder in which a piston is moved cyclically between top dead center and bottom dead center. The working cylinder comprises two intake valves and two exhaust valves that are associated with two camshafts (16,18). The camshaft (18) has adjuster (28) that adjusts valve timing and the camshaft (16) that operates valve in non-variable timing. The opening degree of the exhaust valves is set to 0-25 [deg] corresponding to bottom dead center of the piston. An independent claim is included for method for operating internal combustion engine.