Variable Cam Timing Phaser Dual Control Valves
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Solution Overview
Problem
Existing cam timing phaser arrangements in commercial vehicles face issues with mechanical complexity, sensitivity to impurities, oil leakage, and durability due to the use of multi-positional spool valves and check valves, leading to compromised performance and increased costs.
Innovation Solution
A variable cam timing phaser arrangement utilizing a rotor with vanes and a stator, along with a control assembly featuring a piloted valve and solenoid-controlled actuator, which simplifies the system by using only on/off valves and reducing the complexity of hydraulic components, thereby minimizing oil leakage and enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-positional spool valves and check valves are used in cam timing phaser arrangements, then camshaft timing control is achieved, but mechanical complexity increases and sensitivity to impurities worsens
Solution Approach 1:
The patent divides the cam timing phaser into distinct functional segments: a rotor with cam-driven vanes that generate periodic torque, a stator with hydraulic chambers, and a simplified spool valve with only two positions (advance/retard). This segmentation allows each component to perform its specific function with reduced complexity, eliminating the need for multi-positional valves while maintaining timing control capability
Solution Approach 2:
The patent extracts and eliminates the check valves from the system by using a simplified spool valve design with direct oil flow control. The spool valve directly connects the hydraulic oil supply to either the advance chamber or retard chamber without requiring intermediate check valves, thereby reducing mechanical complexity and sensitivity to impurities while preserving the cam torque actuation mechanism
2Measurement precision
If multi-positional spool valves are used, then precise timing control is achieved, but oil leakage increases
Solution Approach 1:
The patent employs a simplified spool valve design with fewer moving parts and sealing surfaces compared to multi-positional valves. The reduced complexity of the valve mechanism inherently decreases the number of potential leakage paths, making the system more robust against oil leakage while maintaining sufficient timing control precision for cam phasing operations
3Reliability
If check valves are used in the rotor, then hydraulic ratchet effect is achieved, but device complexity increases
Solution Approach 1:
The patent merges the functions of the spool valve and check valve operations into a single simplified spool valve mechanism. The spool valve directly controls oil flow direction to achieve the hydraulic ratchet effect through cam torque actuation, eliminating the need for separate check valves in the rotor and thereby reducing device complexity while maintaining the desired hydraulic functionality
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 results in a more robust, less complex, and less prone to oil leakage cam phaser system, improving performance and reducing manufacturing costs by eliminating the need for precise regulation and specialized tools, while maintaining reliable camshaft timing control.
Implementation Method 1
The spool valve is moved to each of the three operative positions using a variable force solenoid
Implementation Method 2
The resulting difference in oil pressure between the advance chamber and the retard chamber makes the rotor rotate relative to the stator
Implementation Method 3
The reverse direction of fluid flow is blocked by check valve. Therefore, the rotor will be rotationally shifted relative to the stator every period the torque acts in the relevant direction
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
A variable cam timing phaser arrangement (201) is disclosed, comprising: a rotor (9) having at least one vane; a stator (7) co-axially surrounding the rotor (9), having at least one recess for receiving the at least one vane of the rotor, wherein the at least one vane divides the at least one recess into a first chamber (11) and a second chamber (13); and a control assembly for regulating hydraulic fluid flow from the first chamber (11) to the second chamber (13) or vice-versa. The control assembly comprises a central on/off piloted valve (15) for allowing or preventing fluid flow along a first unidirectional flow path between the first (11) and second (13) chambers, and a central solenoid valve (37) for allowing or preventing fluid flow along a second unidirectional flow path between the first (11) and second (13) chambers in the opposite direction to the first flow path. The present disclosure further relates to an integrated valve unit for use in the variable cam timing phaser arrangement, and a method of controlling the timing of a camshaft in an internal combustion engine. The disclosure also relates to an internal combustion engine and a vehicle comprising the disclosed variable cam timing phaser arrangement.