Variable Valve Rocker Arm Actuator for Speed-Independent Timing
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Solution Overview
Problem
Conventional internal combustion engines with variable valve timing systems face challenges in maintaining consistent valve action switching due to varying inertial forces at different engine speeds, limiting their applicability to specific engine speed ranges.
Innovation Solution
The engine employs a rocker arm system with a hydraulic actuator and trigger mechanism, allowing the rocker arm to selectively engage with cams by sliding axially, and a disengagement member that moves orthogonally to disengage the stopper, ensuring consistent valve action timing across all engine speeds through a simple configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional engagement member and protruding portion mechanism is used, then the valve action switching can be achieved at predetermined engine speeds, but the timing of restriction removal varies with engine speed due to varying inertial forces
Solution Approach 1:
The patent replaces the conventional mechanical inertial force-based engagement member flipping mechanism with a hydraulic actuator system. The hydraulic actuator uses fluid pressure to move the rocker-arm shaft axially, which in turn activates the disengagement member to move the stopper. This substitution eliminates the dependency on engine speed-dependent inertial forces, providing consistent valve action switching timing across all engine speeds.
Solution Approach 2:
The patent introduces a hydraulic actuator that uses hydraulic pressure to drive the rocker-arm shaft in the axial direction. The hydraulic system provides controlled, consistent actuation force regardless of engine speed variations, enabling the disengagement member to reliably disengage the stopper from the rocker arm at the correct timing across the entire engine operating range.
2Ease of operation
If the engagement member is flipped up by inertial force, then the restriction on sliding movement is removed, but the inertial force varies with engine speed causing timing variations
Solution Approach 1:
The patent replaces the automatic inertial force-based disengagement mechanism with a hydraulically-controlled system. The hydraulic actuator provides controlled axial movement of the rocker-arm shaft, which reliably actuates the disengagement member to move the stopper away from the rocker arm at the precise intended timing, eliminating timing variations caused by inertial force fluctuations.
3Adaptability or versatility
If the rocker arm slides axially to engage with different cams, then variable valve actions are achieved, but the sliding movement is restricted by the stopper until disengaged
Solution Approach 1:
The patent employs a nested arrangement where the disengagement member is integrated with the rocker-arm shaft structure. The disengagement member is positioned within the axial movement path of the rocker-arm shaft, and the stopper is arranged to be moved by the disengagement member. This nested configuration achieves the necessary restriction and disengagement functions with minimal additional components, reducing overall device complexity.
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 enables reliable and consistent valve action switching irrespective of engine speed, preventing erroneous disengagement and maintaining engine performance across a wide range of speeds.
Implementation Method 1
an actuator (e.g., a hydraulic actuator 65 in the embodiment) that moves the rocker-arm shaft in the axial direction of the rocker-arm shaft
Implementation Method 2
the disengagement member moves in a direction orthogonal to the axial direction, and thereby brings the stopper into action to disengage the stopper from the rocker arm
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
Object The invention aims to provide an internal combustion engine equipped with a variable valve controlling system which switches the actions of an engine valve by sliding a rocker arm in the axial direction of the rocker-arm shaft, while enabling the restriction on the sliding movement of the rocker arm to be removed in accordance with the timings of the actions of the rocker-arms irrespective of the engine speed. Solving Means The internal combustion engine (1) includes: an actuator (65) that moves a rocker-arm shaft (14) in its axial direction; a trigger arm (33) that engages with a rocker arm (13) to prohibit the sliding movement of the rocker arm (13); and a trigger pin (37) which is activated by an axial-direction movement of the rocker-arm shaft (14) and which brings the trigger arm (33) into action to disengage the trigger arm (33) from the rocker arm (13).