Switchable Lever Coupling Assembly Actuation
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Solution Overview
Problem
Existing switchable lever systems in internal combustion engine valve trains face challenges in packaging space and efficiency due to the need for hydraulic fluid galleries and slower actuation times, particularly in achieving different discrete valve lifts within limited engine spaces.
Innovation Solution
A switchable lever system with a coupling assembly that includes push pins and a coupling pin, actuated by an electric actuator, allowing for selective locking and unlocking of the inner and outer levers, enabling different valve lift modes through a cam-form interface and bias spring assistance, with actuation possible from either side of the lever.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic fluid galleries are used to actuate the coupling assembly, then the system can achieve valve lift switching, but the packaging space within the engine is increased and the system complexity is increased
Solution Approach 1:
The patent extracts and eliminates the hydraulic fluid galleries from the switchable lever system, replacing them with an electric actuator that directly actuates the coupling pin through push pins. This removal of the hydraulic gallery network significantly reduces the packaging space required within the engine while maintaining the valve lift switching capability.
Solution Approach 2:
The patent replaces the hydraulic actuation system with an electric actuator system. The electric actuator uses electromagnetic or electrostatic fields to move the push pins, which in turn actuate the coupling pin mechanically. This substitution eliminates the need for hydraulic fluid delivery infrastructure, reducing overall system volume and complexity.
2Adaptability or versatility
If hydraulic fluid actuation is used for the coupling assembly, then the system can switch between valve lift modes, but the actuation time is slower
Solution Approach 1:
The patent replaces the hydraulic actuation mechanism with an electric actuator that directly drives the coupling pin through push pins. Electric actuators respond almost instantaneously to control signals, eliminating the fluid compression and flow delays inherent in hydraulic systems. This results in significantly faster actuation times for switching between valve lift modes.
3Adaptability or versatility
If hydraulic fluid system is implemented for switchable lever actuation, then the coupling can be actuated, but the operating temperature range is limited
Solution Approach 1:
The patent replaces the hydraulic fluid-based actuation system with an electric actuator system. Electric actuators are not constrained by fluid viscosity changes across temperature ranges and can operate reliably from very cold to very hot conditions. The electric motor or solenoid components maintain consistent performance across a wide temperature spectrum, eliminating the thermal limitations of hydraulic systems.
Data Source
AI summary
A switchable lever is provided that includes an outer lever, an inner lever pivotably mounted to the outer lever, and a coupling assembly capable of selectively locking the inner lever to the outer lever. The coupling assembly is arranged to be actuated from either a first side or a second side of the switchable lever. The coupling assembly can have one or more push pins and a coupling pin that is arranged to be actuated by the one or more push pins. An actuated end of the coupling pin can be formed with a receiving land that is configured to engage a cam form on a second end of the one or more push pins.