Variable Cam Phaser Locking Mechanism for Hybrid Engine Starts
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Solution Overview
Problem
Existing cam phasers in vehicles lack the ability to optimally lock at intermediate positions for both cold and hot engine starts, as they rely on natural positive stops which are not present, and fail to differentiate between hybrid vehicle conditions where the electric motor is active or inactive, affecting engine performance.
Innovation Solution
A cam phaser design with a stator and rotor configuration that includes lock pins and springs, allowing the rotor to be locked at specific intermediate positions based on the status of the electric motor, using alignment and biasing mechanisms to secure the rotor relative to the stator, enabling optimal cam phasing for both cold and hot starts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cam phaser uses natural positive stops for locking, then the structure is simple, but the cam phaser cannot lock at intermediate positions optimally for cold and hot starts
Solution Approach 1:
The locking mechanism is segmented into multiple lock pins (first lock pin, second lock pin, third lock pin) that can independently engage with different lock pin seats corresponding to different intermediate positions. This segmentation allows the cam phaser to lock at multiple specific positions rather than relying on a single natural positive stop, resolving the contradiction between reliable intermediate position locking and structural simplicity.
Solution Approach 2:
Spring mechanisms are introduced as intermediary elements to bias the lock pins toward their respective lock pin seats. These springs provide the necessary force to ensure reliable engagement at intermediate positions without requiring complex active control systems, thus maintaining relative structural simplicity while achieving reliable locking.
2Adaptability or versatility
If the cam phaser locks at a single position, then the structure is simple, but it cannot differentiate between hybrid vehicle conditions (electric motor active or inactive) to optimize performance
Solution Approach 1:
The locking mechanism transitions from a static single-position lock to a dynamic multi-position system. The rotor can be locked at different intermediate positions (first intermediate position with first lock pin, or second intermediate position with second and third lock pins) depending on operating conditions such as whether the electric motor is active or inactive, enabling adaptability to hybrid vehicle conditions.
Solution Approach 2:
Different lock pin seats are positioned at specific locations around the rotor-stator assembly, each corresponding to optimal cam phasing for different operating conditions. The first lock pin seat corresponds to one intermediate position while the second and third lock pin seats correspond to another intermediate position, allowing local optimization for different vehicle operating modes.
3Reliability
If the cam phaser uses multiple lock pins and lock pin seats, then it can lock at multiple intermediate positions, but the device complexity increases
Solution Approach 1:
The second lock pin and third lock pin share a common spring mechanism (second spring) that biases both pins simultaneously. This merging of the biasing mechanism reduces the total number of springs required compared to having separate springs for each lock pin, thereby reducing device complexity while maintaining the ability to lock at multiple positions with high reliability.
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
Enables enhanced engine performance by allowing the cam phaser to lock at positions optimal for cold and hot starts, improving fuel efficiency and reducing emissions by adjusting valve timing based on engine conditions, particularly in hybrid vehicles.
Implementation Method 1
The cam phaser further includes a spring operatively coupled to the first lock pin. The spring is configured to bias the first lock pin toward the first lock pin seat.
Data Source
AI summary
A cam phaser includes a rotor, a stator, and a cover. The rotor defines a first hole and a second hole and can rotate relative to the stator between a first intermediate position and a second intermediate position. The cover is mounted on the stator and defines a first lock pin seat and a second lock pin seat. The cam phaser includes a first lock pin and a second lock pin. The first lock pin can move along the first hole and into the first lock pin seat to lock the rotor relative to the stator at the first intermediate position. The second lock pin can move along the second hole and into the second lock pin seat to lock the rotor relative to the stator at the second intermediate position.