Hydraulic Cam Phaser Pressure Boosting at Low Engine Oil Pressure
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Solution Overview
Problem
Hydraulic cam phasers in combustion engines face challenges in achieving quick and robust phase-shifting functions at low oil pressures, particularly during low engine speed or transition from idling to higher load conditions, which can lead to insufficient oil pressure for effective phase-shifting.
Innovation Solution
The implementation of a hydraulic cam phaser system that utilizes an accumulator to store pressurized oil, supplemented by a pressure media-controlled cylinder to increase oil pressure during phase-shifting, allowing for faster and more robust regulation of camshaft positions, even at reduced engine oil pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If oil pressure in the engine is decreased to use a smaller oil pump, then parasitic losses and fuel consumption are reduced, but the phase-shifting function becomes insufficient at low engine speeds or during transitions from idling to higher load
Solution Approach 1:
The accumulator is pre-filled with pressurized oil before the phase-shifting operation begins. This preliminary storage of high-pressure oil ensures that when phase-shifting is needed, immediately available high-pressure oil can be supplied to the cam phaser, resolving the contradiction between using a smaller pump (lower continuous pressure) and maintaining reliable phase-shifting capability.
Solution Approach 2:
The accumulator acts as an intermediary between the smaller oil pump and the cam phaser. It receives oil from the pump and transforms it into high-pressure oil on demand, mediating between the limited output of the smaller pump and the high-pressure requirements of the phase-shifting mechanism.
2Productivity
If a larger oil pump is used to maintain high oil pressure for robust phase-shifting, then phase-shifting speed and robustness are improved, but parasitic losses and fuel consumption increase
Solution Approach 1:
The accumulator stores high-pressure oil in advance, eliminating the need for a large pump to continuously maintain high pressure. The pump only needs to fill the accumulator at a moderate rate, while the accumulator provides instantaneous high-pressure oil for rapid phase-shifting when needed.
Solution Approach 2:
The system uses periodic action by accumulating pressure over time and releasing it in short bursts during phase-shifting events. This allows the use of a smaller pump that operates continuously at lower power consumption, while still achieving the high power output needed for rapid phase-shifting when required.
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 faster and more robust phase-shifting of camshaft positions, reducing parasitic losses and fuel consumption by allowing the use of a smaller oil pump while maintaining high pressure for effective valve timing control.
Implementation Method 1
a pressure media controlled cylinder (71) is arranged in the accumulator (60) and is adapted to increase the pressure of the oil in the first chamber (65) of the accumulator (60)
Implementation Method 2
An oil pump (6) is arranged at the combustion engine (3) to pump oil through the oil channels
Implementation Method 3
Hydraulic cam phasers in combustion engines face challenges in achieving quick and robust phase-shifting functions
Data Source
Figure 1~2
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AI summary
A phase- shifting device (29), a so-called cam phaser, is arranged between a crankshaft and at least one camshaft (20,23) to change the at least one camshaft's (20, 23) rotational position in relation to the crankshaft (15) 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 (29) is connected to an accumulator (60) that can be charged by an oil pump (6). The oil pressure may be increased with the help of a pressure medium controlled cylinder (71) before or during a phase- shifting process.