Switchable Rocker Arm Hydraulic Coupling for Valve Deactivation
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Solution Overview
Problem
Existing switchable valve train components in internal combustion engines face packaging challenges due to the need for a lost motion spring and arcuate lost motion, which also require a camshaft abutment and base circle lobe, leading to friction and wear, and limited switching time at higher engine speeds.
Innovation Solution
A switchable rocker arm design with a hydraulically actuated coupling assembly, featuring a shuttle pin, locking pin, and resilient element, that eliminates the need for a camshaft abutment and base circle lobe, allowing for minimal lost motion packaging and efficient valve deactivation without external housing for lost motion springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lost motion spring and arcuate lost motion are used in switchable valve train components, then valve deactivation can be achieved, but packaging space requirements increase and friction and wear occur due to camshaft abutment and base circle lobe
Solution Approach 1:
The patent removes the lost motion spring and arcuate lost motion features from the switchable rocker arm design. Instead, it uses a direct hydraulic actuation system with a solenoid valve that controls oil pressure to move a plunger and pivot the rocker arm between active and deactivated positions, eliminating the need for traditional spring-based lost motion mechanisms and their associated packaging requirements
Solution Approach 2:
The patent replaces the mechanical spring-based lost motion system with a hydraulic actuation system. The solenoid-controlled hydraulic pressure directly pivots the rocker arm, substituting mechanical elasticity with fluid pressure control to achieve valve deactivation with reduced packaging space and without the friction and wear of camshaft abutments
2Reliability
If camshaft abutment and base circle lobe are used, then valve deactivation is enabled, but friction and wear increase
Solution Approach 1:
The patent replaces the mechanical camshaft abutment and base circle lobe interaction with a hydraulic actuation system. The solenoid valve controls hydraulic pressure to move a plunger that directly pivots the rocker arm, eliminating the sliding friction and wear between camshaft components while enabling the same valve deactivation function
Solution Approach 2:
The patent uses a hydraulic actuation system where engine oil pressure, controlled by a solenoid valve, acts on a plunger to pivot the rocker arm between active and deactivated positions. This hydraulic mechanism replaces the mechanical friction-based camshaft abutment system, reducing harmful friction and wear while maintaining reliable valve deactivation
3Reliability
If traditional electro-hydraulic coupling assembly is used, then valve lift switching is achieved, but switching time is limited by camshaft rotation through base circle portion
Solution Approach 1:
The patent removes the base circle lobe and traditional electro-hydraulic coupling assembly from the design. Instead, it uses a direct hydraulic actuation system where solenoid-controlled pressure directly pivots the rocker arm, eliminating the time delay associated with camshaft rotation through the base circle portion and enabling faster switching between valve lift modes
Solution Approach 2:
The patent positions the hydraulic actuation system so that the solenoid valve can immediately actuate the plunger and pivot the rocker arm when switching is required, without waiting for the camshaft to complete a base circle rotation. This preliminary positioning of the hydraulic system enables immediate response and reduces switching time, particularly at higher engine speeds
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 design enables efficient valve deactivation with reduced packaging space requirements, minimized friction, and improved switching speed at higher engine speeds, enhancing engine efficiency and fuel economy.
Implementation Method 1
a resilient element or spring that acts on the locking pin
Implementation Method 2
The electro-hydraulic system typically contains at least one solenoid valve within an array of oil galleries that manages engine oil pressure to either lock or unlock the coupling assembly
Data Source
AI summary
A switchable rocker arm for valve deactivation is provided for a valve train of an internal combustion engine. The switchable rocker arm includes a cam lever assembly, a valve lever assembly, and a hydraulically actuated coupling assembly that is radially arranged between the cam lever and valve lever assemblies. The coupling assembly includes a shuttle pin, a locking pin with a round or flat locking interface, and optional shuttle pin and locking pin sleeves. In a first, locked position, the rotational motion of a camshaft is translated to linear motion of an engine valve. In a second, unlocked position, the cam lever assembly rotates about the valve lever assembly, facilitating valve deactivation. A pivot joint arranged between the cam lever and valve lever assemblies facilitates an arcuate lost motion of the cam lever assembly. An integrated arrangement for one or more lost motion springs offers packaging and functional advantages.