Hydraulic Unit Siphon Venting for Engine Leakage
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Solution Overview
Problem
The existing hydraulic units for internal combustion engines with hydraulically variable gas exchange valve trains face issues with hydraulic leakage when idle for extended periods, leading to air entering the pressure chamber and preventing engine starting due to vacuum creation and medium shrinkage, which affects the rigidity and functionality of the gas exchange valve.
Innovation Solution
The hydraulic unit incorporates a siphon ventilation duct with a downward and upward section, ensuring a hydraulic reservoir to compensate for medium shrinkage and maintaining negative pressure to prevent leakage, featuring a third duct section for complete sealing and air bubble management to inhibit air re-entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vent channel is opened to allow air bubbles to escape from the pressure relief chamber, then air separation is improved, but hydraulic fluid leakage increases during idle periods
Solution Approach 1:
The vent channel is divided into three distinct sections: a first downward-leading section, a second upward-leading section forming a siphon, and a third downward-leading section. This segmentation creates different functional zones within the vent channel, allowing air bubbles to be vented while preventing hydraulic fluid leakage during idle periods through the siphon effect and gravity-assisted flow control.
2Loss of substance
If the hydraulic unit is sealed completely to prevent leakage, then fluid retention is improved, but air bubbles cannot be vented from the pressure relief chamber
Solution Approach 1:
The vent channel design dynamically adapts its function based on operating conditions. During operation, the channel allows air bubbles to escape through the siphon structure. During idle periods, the same channel structure, combined with the siphon geometry and gravity, prevents hydraulic fluid leakage by creating a seal through the fluid column in the upward-leading section.
3Reliability
If the vent channel opens geodesically high to allow air venting, then air separation is improved, but hydraulic fluid leaks through the guide gap more easily
Solution Approach 1:
Instead of opening the vent channel at the highest point, the design inverts the approach by having the channel open geodesically low through the third downward-leading section. The siphon structure with its upward-leading middle section creates a counter-intuitive flow path that uses gravity and pressure differentials to prevent leakage while maintaining effective air venting capability.
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 design effectively reduces hydraulic leakage, maintaining a critical filling level for engine starting and preventing air bubbles from entering the pressure chamber, ensuring reliable engine operation even after prolonged idle times.
Implementation Method 1
the vent channel (11) has a siphon with a first channel section (14) leading downstream in the direction of venting, geodetically downwards, and a second channel section (15) leading upwards
Implementation Method 2
the cooling hydraulic fluid, which shrinks in volume, creates a vacuum in the hydraulic chambers
Implementation Method 3
During this pressure equalization, gravity causes the hydraulic chambers to empty into the surrounding environment via the leakage through the guide gap between the slave piston and the hydraulic housing
Data Source
Figure 1
Figure 2
AI summary
What is proposed is a hydraulics unit for an internal combustion engine with a hydraulically variable gas exchange valve gear, comprising: – a hydraulics casing (4) with a pressure chamber (5), a pressure relief chamber (6) and a venting duct (11, 11'), wherein the pressure chamber, the pressure relief chamber and the venting duct are hydraulically connected to one another, – a master piston (7) which is guided in the hydraulics casing, is driven on the casing outer side by a cam (3) and, on the casing inner side, bounds the pressure chamber, – a slave piston (8) which is guided in the hydraulics casing, drives the gas exchange valve (2) on the casing outer side and, on the casing inner side, bounds the pressure chamber, – and a hydraulics valve (9) which, in the closed state, interrupts the connection between the pressure relief chamber and the pressure chamber. The venting duct is connected, on the casing inner side, to the pressure relief chamber via a throttle point (12) and opens on the casing outer side. The venting duct has a siphon with a downward first duct section and an upward second duct section, respectively in the direction of gravity and in the venting direction, wherein, when the gas exchange valve is closed, the lowermost section (17) of the siphon is below the boundary (13) of the pressure chamber of the slave piston.