Cam Phaser Oil Pressure Boosting for Fast Valve Timing Shift
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Solution Overview
Problem
Hydraulic cam phasers in combustion engines face challenges in achieving quick and robust phase-shifting due to insufficient oil pressure, especially at low engine speeds or during transitions, which can lead to reduced engine performance and increased fuel consumption.
Innovation Solution
The implementation of a pressure media controlled cylinder connected to an accumulator, which increases oil pressure for the cam phaser, allowing for faster and more robust phase-shifting by using a smaller oil pump, thereby reducing parasitic losses and fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a larger oil pump is used to increase oil pressure for quick phase-shifting, then phase-shifting speed and robustness improve, but parasitic losses and fuel consumption increase
Solution Approach 1:
The system uses periodic action by charging the accumulator tank with pressurized oil during normal operation and then releasing this stored pressure during phase-shifting operations. This allows the cam phaser to receive high pressure oil on demand without requiring the oil pump to continuously operate at high pressure, thereby reducing parasitic losses while maintaining fast phase-shifting capability.
Solution Approach 2:
The accumulator tank performs preliminary action by pre-storing pressurized oil before it is needed for phase-shifting. The oil is pressurized in advance during periods when phase-shifting is not required, and this pre-pressurized oil is then available for immediate use when phase-shifting is needed, eliminating the need for a large continuous-duty oil pump.
2Loss of energy
If oil pressure is reduced to use a smaller oil pump, then parasitic losses decrease, but phase-shifting function becomes slow and unreliable at low engine speeds
Solution Approach 1:
The accumulator tank acts as an intermediary between the oil pump and the cam phaser. It receives pressurized oil from the pump during normal conditions and then supplies this stored pressure to the cam phaser during phase-shifting operations. This intermediary allows the system to maintain high pressure for reliable phase-shifting without requiring the pump to continuously generate high pressure, thus reducing parasitic losses.
3Device complexity
If EGR-systems are eliminated using cam phasers for emission control, then system complexity decreases, but sufficient oil pressure for reliable phase-shifting becomes more challenging to maintain
Solution Approach 1:
The system dynamically adjusts oil pressure delivery to the cam phaser based on operational needs. The accumulator tank provides high pressure oil during phase-shifting operations when it is most needed, while allowing lower system pressure during normal operation. This dynamic pressure management ensures reliable phase-shifting performance without requiring continuously high system pressure, making the elimination of EGR-systems feasible.
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 solution enables very fast and robust regulation of cam phasers with high pressure, reducing oil pump size and parasitic losses, thus improving engine performance and fuel efficiency.
Implementation Method 1
add oil to an accumulator tank in which the oil pressure may be increased with the help of a spring-loaded piston or similar
Implementation Method 2
Cam phasers may be used in combustion engines to change the rotational positions of camshafts in relation to each other and in relation to a crankshaft in order to phase-shift
Data Source
AI summary
A phase-shifting device, a so-called cam phaser, is arranged between a crankshaft and at least one camshaft to change the at least one camshaft's rotational position in relation to the crankshaft and thus push forward or defer at least one inlet valve's and/or at least one exhaust valve's opening and closing time. The phase-shifting device is connected to an accumulator that can be charged by an oil pump. The oil pressure may be increased with the help of a pressure medium controlled cylinder before or during a phase-shifting process.