Variable Cam Timing Phaser with Remote Piloted Valve for Intermediate Locking
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Solution Overview
Problem
Existing variable cam timing systems face challenges in efficiently positioning the phaser to an intermediate phase angle position while maintaining a compact package length and optimizing performance, due to the complexity and length issues associated with combining hydraulic circuits for control, detent, and lock pin functions.
Innovation Solution
The introduction of a remote piloted valve that controls the hydraulic detent switching function, allowing for active positioning of the phaser to an intermediate phase angle by blocking or allowing fluid flow between the advance and retard chambers, and simultaneously controlling the lock pin, thereby simplifying the hydraulic circuit and enhancing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If all three hydraulic circuits (VCT control, hydraulic detent, and lock pin control) are combined on one spool valve, then the system integrates multiple functions in a single component, but the spool valve and sleeve become very long and difficult to manufacture, and the overall package length increases
Solution Approach 1:
The patent divides the hydraulic control system into separate spool valves: one spool valve controls the VCT phaser position, and another spool valve controls both the lock pin and hydraulic detent circuit. This segmentation reduces the length and complexity of each individual spool valve while maintaining full functional control of the VCT system.
2Adaptability or versatility
If all three hydraulic circuits are combined on one spool valve, then multiple functions are controlled in a single component, but the overall package length of the VCT increases
Solution Approach 1:
By separating the hydraulic control circuits into distinct spool valves, the patent reduces the overall package length of the VCT assembly while maintaining the ability to control VCT position, lock pin engagement, and hydraulic detent positioning independently.
3Adaptability or versatility
If all three control circuits are placed on one spool valve, then a single component controls all functions, but the flow circuits become complex and restrictive, limiting the performance of each circuit
Solution Approach 1:
The patent separates the hydraulic control circuits into different spool valves, allowing each circuit to have optimized flow paths and reducing cross-interference between control functions. This improves the responsiveness and performance of each individual control circuit.
Solution Approach 2:
The patent introduces a pilot circuit that uses a small amount of hydraulic fluid to control the main spool valve positions. This intermediary approach allows for precise control of the lock pin and hydraulic detent circuits without requiring large flow capacities in the main control lines.
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 the phaser to be efficiently positioned to an intermediate phase angle, reducing the overall package length and improving performance by simplifying the hydraulic detent circuit and allowing for active control of the lock pin, ensuring reliable engine operation even without electronic controls.
Implementation Method 1
When the piloted valve is in the second position, fluid is allowed to flow between the detent line from the advance chamber and the detent line from the retard chamber through the piloted valve and a common line
Implementation Method 2
The lock pin is moved from a locked to an unlocked position by hydraulic pressure
Data Source
AI summary
A variable cam timing phaser for an internal combustion engine including a piloted valve in the rotor assembly, movable from a first position to a second position, and detent lines communicating with the advance chamber or the retard chamber are restricted and or blocked when the rotor assembly is in or near an intermediate phase angle position. When the piloted valve is in the first position, fluid is blocked from flowing through the piloted valve. When the piloted valve is in a second position, fluid is allowed to flow between the detent line from the advance chamber and the detent line from the retard chamber through the piloted valve and a common line, such that the rotor assembly is moved to and held in the intermediate phase angle position relative to the housing assembly.