Connecting Rod Switching Valve Leakage Control
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Solution Overview
Problem
Existing connecting rods with switching valves in internal combustion engines suffer from hydraulic fluid leakage, leading to unwanted changes in connecting rod length and compression ratio due to mechanical jamming and play between the piston and housing, which affects the engine's efficiency and stability during variable compression operations.
Innovation Solution
Integration of two check valves within the switching valve, actuated mechanically via profile surfaces, to control hydraulic fluid flow between the fluid lines and relief channels, preventing leakage and ensuring stable operation by maintaining the desired compression ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If play is provided between the pick-off element and the connecting section to prevent jamming, then the reliability of the switching valve is improved, but hydraulic fluid leakage increases
Solution Approach 1:
The pick-off element is divided into a piston section and a control section, with the piston section having a first diameter and the control section having a second diameter. This segmentation allows the piston section to fit tightly in the piston bore for sealing, while the control section provides the necessary play for reliable operation without causing leakage.
Solution Approach 2:
Different sections of the pick-off element have different diameters to serve different functions. The piston section has a larger diameter for tight sealing against the piston bore, while the control section has a smaller diameter to allow play for operational reliability. This local differentiation resolves the contradiction between sealing and reliability.
2Loss of substance
If a tight fit is used between the pick-off element and the connecting section to prevent leakage, then hydraulic fluid leakage is reduced, but the pick-off element may jam
Solution Approach 1:
The pick-off element is segmented into functional sections with different diameters. The piston section provides tight fitting for leakage prevention, while the control section provides clearance for reliable operation, thus resolving the contradiction between preventing leakage and preventing jamming.
Solution Approach 2:
The pick-off element has non-uniform diameter along its length, with the piston section having a larger diameter for sealing and the control section having a smaller diameter for play. This local quality differentiation allows simultaneous achievement of tight sealing and operational reliability.
3Productivity
If the connecting rod length is adjusted to improve compression ratio, then engine efficiency is improved, but positional stability decreases due to leakage
Solution Approach 1:
The pick-off element's segmented structure with different diameters ensures tight sealing while maintaining operational reliability, preventing hydraulic fluid leakage that would cause unwanted changes in connecting rod length and compression ratio, thus maintaining positional stability during efficiency-improving adjustments.
Solution Approach 2:
The differential diameter design of the pick-off element provides local tight sealing at the piston bore interface while maintaining play at the control section, preventing leakage-induced positional drift and ensuring stable connecting rod length during compression ratio adjustments.
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
The solution significantly reduces hydraulic fluid leakage, enhancing the positional stability of the connecting rod and maintaining consistent compression ratios, thereby improving the reliability and efficiency of the internal combustion engine's variable compression mechanism.
Implementation Method 1
two shut-off valves (30, 31) which are integrated into the switchover valve (10) and, depending on the position of the tapping element (12), release or block a flow of hydraulic fluid from the first (17) or the second bore (19) in the direction of the relief channel (22)
Implementation Method 2
which have a tappet (36), which can be placed sealingly against a valve seat (38) by means of a spring element (37)
Implementation Method 3
The check valves are actuated via an inner profile (34) of the recess (33)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a changeover valve (10), in particular for controlling a hydraulic fluid flow, with a tap element (12) and a sleeve-shaped connecting section (16) having a first bore (17) for connecting to a first hydraulic fluid line (18), a second bore (19) for connecting to a second hydraulic fluid line (20), and a relief bore (21) for connecting to a relief channel (22). The tap element (12) is arranged in the sleeve-shaped connecting section (16) and can be selectively moved into a first switching position (S1) or a second switching position (S2), wherein in the first switching position (S1) the first hydraulic fluid line (18) is connected to the relief channel (22) and in the second switching position (S2) the second hydraulic fluid line (20) is connected to the relief channel (22).According to the invention, two shut-off valves (30, 31) are provided, which are integrated into the changeover valve (10) and which, depending on the position of the tap element (12), allow or block the flow of hydraulic fluid from the first or the second bore (17, 19) towards the relief channel (22). The invention further relates to a connecting rod (1) with such a changeover valve (10).