Cam Profile Switch Assembly for Cold-Start Emission Reduction
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Solution Overview
Problem
Existing engine emission control systems face challenges in reducing cold-start emissions due to the inefficiency of exhaust catalysts at low temperatures, and secondary air injection systems add cost and weight while being redundant during other engine conditions.
Innovation Solution
A cam profile switch (CPS) assembly that independently adjusts cam profiles for intake and exhaust valves using two concentric hollow cylinders and locking mechanisms, allowing for different cam profiles to be used based on engine operating conditions to expedite exhaust heating and improve emissions and fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a secondary air injection system with a dedicated pump is included to increase exhaust temperature and reduce cold-start emissions, then emissions are reduced, but cost and weight increase
Solution Approach 1:
The CPS assembly enables the existing camshaft system to perform multiple functions by providing different cam profiles for different operating conditions. The same camshaft mechanism that controls valve operation during normal operation is reused during cold-start by switching to a specific cam profile, eliminating the need for a dedicated cold-start air injection system
Solution Approach 2:
The system dynamically switches between different cam profiles based on engine operating conditions. During cold-start, the CPS assembly transitions to a first cam profile that optimizes valve timing and duration to enhance exhaust heating, while during normal operation it switches to a second cam profile for standard performance
2Object-affected harmful factors
If a secondary air injection system with a dedicated pump is included to increase exhaust temperature and reduce cold-start emissions, then emissions are reduced, but device complexity increases
Solution Approach 1:
The CPS assembly enables the existing camshaft system to perform multiple functions by providing different cam profiles for different operating conditions. The same camshaft mechanism that controls valve operation during normal operation is reused during cold-start by switching to a specific cam profile, eliminating the need for a dedicated cold-start air injection system
Solution Approach 2:
The invention merges the cold-start emission control function with the existing camshaft valve actuation system. By integrating the cold-start strategy into the cam profile switching mechanism rather than adding a separate system, the overall device complexity is reduced
3Object-affected harmful factors
If a secondary air injection system with a dedicated pump is included to increase exhaust temperature and reduce cold-start emissions, then emissions are reduced, but packaging space increases
Solution Approach 1:
The CPS assembly enables the existing camshaft system to perform multiple functions by providing different cam profiles for different operating conditions. The same camshaft mechanism that controls valve operation during normal operation is reused during cold-start by switching to a specific cam profile, eliminating the need for a dedicated cold-start air injection system
Solution Approach 2:
The invention extracts the cold-start emission control function from a separate dedicated system and integrates it into the existing camshaft mechanism. This removes the need for additional packaging space for pumps and associated components
4Object-affected harmful factors
If cam profiles are adjusted to open valves to varying degrees during cold-start to improve exhaust heating, then emissions are reduced, but manufacturing complexity increases
Solution Approach 1:
The camshaft system is segmented into multiple independent cam profiles, each optimized for specific operating conditions. The CPS assembly selectively engages different cam profiles by switching between different tappet cylinders, allowing complex valve timing strategies to be implemented through modular, independently manufacturable components
Data Source
AI summary
Methods and systems are provided for actuating an advanced cam profile switch (CPS) assembly. In one example, a system may include a first cylinder and a second cylinder of the CPS assembly that may be independently coupleable to a valve stem via two separate locking mechanisms. A first cam may be selectively engage with the first cylinder and the valve stem and a second cam may be selectively engaged with the second cylinder and the valve stem.