Collapsible Pushrod Valve Actuation for Diesel Compression
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Solution Overview
Problem
Diesel engines face inefficiencies in fuel economy, emissions, and power boost due to high design compression ratios for cold starting, which are not optimal for warm engine operation, and existing valve timing adjustment technologies are not applicable or effective for Diesel engines without altering combustion chamber geometry.
Innovation Solution
A collapsible pushrod system that allows for variable valve timing by partially or fully collapsing a pushrod device, activated by oil pressure, temperature, or electromagnetic mechanisms, enabling reduced valve lift and cylinder deactivation to adjust compression ratios without mechanical interference, and incorporating a damper for smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high compression ratio is used for cold starting, then cold startability is improved, but fuel economy and emissions performance deteriorate during warm operation
Solution Approach 1:
The pushrod is made collapsible to dynamically adjust the valve train geometry. During cold starting, the pushrod maintains its extended state to provide high compression ratio. During warm operation, the pushrod collapses to reduce compression ratio, optimizing fuel economy and emissions. This dynamic structural change allows a single engine design to adapt compression ratio based on operating conditions.
Solution Approach 2:
The invention changes the physical state of the pushrod from extended to collapsed, fundamentally altering the compression ratio parameter. This parameter change enables the engine to operate with high compression during cold start and low compression during warm operation, resolving the contradiction between cold startability and fuel economy.
2Reliability
If a high compression ratio is used for cold starting, then cold startability is improved, but power efficiency under normal operating conditions deteriorates
Solution Approach 1:
The collapsible pushrod enables dynamic adjustment of the valve train to match power output to operational needs. During warm operation, the collapsed pushrod reduces compression ratio to optimize power efficiency and prevent excessive power output that would waste energy during normal driving conditions.
3Loss of energy
If variable valve timing is implemented to improve part load efficiency, then fuel economy improves, but device complexity increases
Solution Approach 1:
The pushrod is segmented into multiple telescoping sections that can collapse independently. This segmentation allows the valve timing mechanism to achieve variable timing without requiring complex camshaft redesigns or additional actuators, as the segmented pushrod itself provides the timing adjustment through its collapse and extension.
Solution Approach 2:
The collapsible pushrod acts as an intermediary mechanism between the camshaft and valve, translating compression ratio changes into valve timing adjustments. This intermediary approach simplifies the overall system compared to direct camshaft timing control, as the pushrod collapse naturally produces the desired valve closure timing changes.
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 improves fuel economy, reduces emissions, and maintains cold startability by allowing lower compression ratios during warm operation, enabling cylinder deactivation for reduced load conditions and increased power boost without altering the combustion chamber design.
Implementation Method 1
the collapsible pushrod device further incorporates a temperature sensitive bi-metal spring to actuate the lock pins to lock or unlock the driver and plunger sections based on engine temperature
Implementation Method 2
the collapsible pushrod device further incorporates an electromagnetic mechanism to lock or unlock the driver and plunger sections
Data Source
AI summary
A valve actuation system is described containing a collapsible pushrod device for use in a reciprocating piston machine cylinder such as an engine. The collapsible pushrod device replaces a conventional pushrod. The system can include a driver base, plunger, and a deactivation pin assembly. In normal operation, the pins lock the driver base and plunger together thereby providing regular valve motion. Under selected conditions, the pin assembly controller unlocks the driver base from the plunger. Valve lift is reduced or eliminated. When eliminated, the cylinder is deactivated. The system can vary the effective compression ratio between higher for cold starting and other selected operating conditions and lower for warmed-up running, as well as trap additional exhaust residuals to assist starting and light load. This is especially useful for Diesel engines. Various means may be used to unlock the pins including oil pressure, bi-metal spring temperature, or electromagnetic activation. The telescoping motion which limits the motion of the valve may occur in one or more steps.