Remote VCT Control Valve with Recirculation for Oil Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing variable camshaft timing (VCT) devices face performance issues at lower RPMs due to low oil pressure and at higher RPMs due to reduced camshaft torque energy, necessitating a solution that can seamlessly switch between torsional assist (TA) and camshaft torque actuation (CTA) functionalities.
Innovation Solution
A VCT phaser assembly and control valve design that allows for remote installation of the control valve, enabling distinct and concurrent TA and CTA phasing functionalities, with a spool and recirculation check valves to manage oil flow effectively between advance and retard chambers, and a remote installation structural interface for non-central mounting, minimizing oil contact and optimizing performance across RPM ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control valve is mounted centrally with respect to housing and rotor components, then the flow of oil among the valve and advance and retard chambers is convenient and efficient, but the valve is exposed to higher risk of oil contact and cannot be installed in remote locations
Solution Approach 1:
The control valve is extracted from the central location within the VCT device and relocated to a remote position on the engine structure. The valve housing includes a remote installation structural interface that enables mounting away from the housing and rotor components, thereby reducing oil contact risk while maintaining functional effectiveness through fluid communication pathways.
2Force
If a TA VCT device uses source oil for advance and retard purposes, then it can provide adequate force at lower RPMs, but low oil pressure at lower RPMs hinders performance
Solution Approach 1:
A recirculation check valve is introduced as an intermediary component to capture and redirect oil that would otherwise be lost during CTA operation. This recirculated oil is directed back to the advance and retard chambers, providing an additional oil supply mechanism that enhances force generation at lower RPMs when source oil pressure is insufficient.
Solution Approach 2:
The VCT device merges TA and CTA functionalities into a single system that can operate in different modes. The control valve is designed to switch between TA and CTA functions as needed, allowing the system to utilize source oil for TA operation at higher RPMs and recirculated oil for CTA operation at lower RPMs, thereby optimizing performance across the entire RPM range.
3Stability of the object's composition
If a CTA VCT device relies on camshaft torque energy and uses recirculated oil, then it can operate independently of source oil pressure, but higher RPMs produce reduced camshaft torque energy which hinders performance
Solution Approach 1:
The control valve incorporates a spool that can dynamically shift position to establish different fluid pathways. The spool moves in response to operating conditions, enabling the system to transition between CTA mode (using recirculated oil) and TA mode (using source oil). This dynamic switching capability allows the system to maintain optimal performance across varying RPM conditions by selecting the appropriate operational mode.
4Adaptability or versatility
If the VCT device merges TA and CTA functionalities into a single device, then it can address shortcomings at both low and high RPMs, but the device complexity increases
Solution Approach 1:
The control valve is designed as a universal component that performs multiple functions: it controls both TA and CTA operations, switches between different oil supply sources, and manages fluid pathways for both advance and retard chambers. This multi-functionality is achieved through a compact design featuring a spool mechanism and recirculation check valve that enable the single valve to handle diverse operational requirements across the entire RPM range.
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 enhances VCT performance by allowing efficient switching between TA and CTA modes, improving engine operation at various RPMs by managing oil flow and reducing the risk of oil contact, thus addressing the limitations of traditional VCT devices.
Implementation Method 1
These camshaft phasers are often hydraulically-actuated. In hydraulically-actuated VCT devices, valves are typically mounted centrally with respect to housing and rotor components of the VCT devices in order to regulate the flow of oil to and from the components
Implementation Method 2
The recirculation check valve(s) is situated at the spool. The first recirculation path can be established between the valve housing and spool depending upon the position of the spool in the valve housing's bore
Implementation Method 3
The valves are part of a larger center bolt assembly. The valve's mounting and its centrality offer convenient and efficient flow of oil among the valve and advance and retard chambers established by the housing and rotor components to carry out advance and retard functionalities
Data Source
AI summary
A variable camshaft timing (VCT) phaser assembly and control valve are employed for use in an internal combustion engine. The VCT phaser assembly has a housing and a rotor. The control valve is installed at a location that is remote of the housing and rotor, and apart from a center bolt site of the housing and rotor. The control valve has a valve housing and a spool located in the valve housing. The valve housing has different ports for fluid communication with a source, an advance line, and a retard line. One or more recirculation paths can be established at various times between the valve housing and the spool, depending upon the position of the spool in the valve housing.