Valve Timing Adjuster Bypass Valve Pressure Relief
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Solution Overview
Problem
The existing valve timing adjusting apparatuses face issues with unstable vane rotor positioning due to torque changes, leading to increased fluid pressure and potential slapping sounds, especially when the engine is started, and the response time for reaching target phase is decreased.
Innovation Solution
A valve timing adjusting apparatus with a housing and vane rotor system that includes retarding and advancing fluid paths, a lock member, and a check valve with a bypass passage and control valve to manage fluid pressure and prevent fluid discharge, ensuring stable positioning and reduced slapping sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a check valve is provided to prohibit working fluid discharge from fluid chambers, then the response time for reaching target phase is improved, but the fluid pressure in the fluid chamber is largely increased to a value higher than the fluid supply source pressure
Solution Approach 1:
A bypass passage is introduced as an intermediary path that allows excess fluid pressure to be relieved. The bypass passage includes a control valve that opens when fluid pressure exceeds a predetermined threshold, providing a safety mechanism to prevent dangerous pressure buildup while maintaining the primary check valve function of preventing fluid discharge during normal operation.
Solution Approach 2:
The bypass passage with control valve acts as a pre-established pressure relief mechanism. Before pressure can reach dangerous levels, the control valve provides a predetermined path for pressure equalization, cushioning against excessive pressure buildup that would otherwise occur when the check valve prevents fluid discharge.
2Ease of operation
If the fluid pressure in the fluid chamber is increased to move the lock member from the housing, then the locked condition of the vane rotor to the housing is released, but the vane rotor is not stably positioned when the fluid pressure is still low shortly after engine start-up
Solution Approach 1:
The lock member is designed to be engaged with the housing before the engine starts, providing stable positioning of the vane rotor during the period when fluid pressure is still low. This preliminary mechanical locking action prevents the vane rotor from being unstable before hydraulic pressure becomes sufficient to operate the control valve.
Solution Approach 2:
The system transitions from a purely mechanical positioning system to a hybrid system where a mechanical lock member provides initial stability, which is then replaced by hydraulic pressure control once the engine starts and fluid pressure builds up. The lock member is automatically released when fluid pressure exceeds the predetermined threshold, transferring the positioning function from mechanical to hydraulic control.
3Stability of the object's composition
If a lock member is provided to lock the vane rotor to the housing, then the vane rotor is stably positioned, but the locked condition may be erroneously released when fluid pressure is rapidly increased
Solution Approach 1:
The control valve is designed with a specific pressure threshold that must be exceeded to activate the bypass passage and release the lock member. By carefully selecting this threshold parameter, the system ensures that the lock is only released when fluid pressure has reached a sufficient level, preventing erroneous release during normal pressure fluctuations while allowing intentional release when pressure is adequately high.
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 improves response time and suppresses slapping sounds by maintaining stable fluid pressure and preventing erroneous lock releases, allowing the vane rotor to smoothly reach its target position without backtracking.
Implementation Method 1
a check valve is provided in one of the branched passage portions connected to a second fluid chamber, which is one of the retarding and advancing fluid chambers other than the first fluid chamber, wherein the check valve allows the fluid flow from the fluid pressure source to the second fluid chamber, but prohibits the fluid flow from the second fluid chamber to the fluid pressure source
Implementation Method 2
The vane rotor is relatively rotated by fluid pressure in the retarding fluid chamber and/or the advancing fluid chamber in a retarding or advancing direction with respect to the housing
Implementation Method 3
a bypass passage is provided between the second fluid chamber and the fluid pressure source, so that the bypass passage bypasses the check valve, and a control valve is provided in the bypass passage for opening and closing the bypass passage in accordance with the fluid pressure of the working fluid introduced into the bypass passage
Data Source
AI summary
A valve timing adjusting apparatus has a housing and a vane rotor to form multiple fluid chambers, and a relative position of the vane rotor to the housing is adjusted by the fluid pressure supplied into the fluid chambers. A check valve is provided in a branched passage portion, so that working fluid may not be pushed out from an advancing fluid chamber to a low pressure side, even when the working fluid in the advancing fluid chamber is temporally compressed to increase its fluid pressure due to a torque change applied from a cam shaft to the vane rotor.