Variable Valve Mechanism Lock Pin Control
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Solution Overview
Problem
Controlling switch timing in variable valve mechanisms of internal combustion engines is challenging, especially in multi-cylinder engines, due to shared oil passages in hydraulic drive devices and the high cost of using electromagnetic solenoids for each cylinder.
Innovation Solution
A variable valve mechanism with an input arm, output arm, lock pin, return spring, and lost motion spring, where the input arm has specific surface features and the lock pin has corresponding surfaces, utilizing an electromagnetic solenoid or hydraulic actuator to control the lock pin's position, allowing self-locking of the valve operation during the base circle phase, enabling reliable switching using the free swinging motion of the input arm, and sharing a single electromagnetic solenoid across multiple cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a hydraulic drive device with shared oil passages is used, then the device complexity is reduced, but the switch timing control becomes difficult
Solution Approach 1:
The patent divides the drive device into independent units for each cylinder, with each cylinder having its own drive device that can be controlled independently. This segmentation allows precise control of switch timing for each cylinder while maintaining relatively simple individual device structures.
2Ease of operation
If electromagnetic solenoids are mounted for each cylinder, then the switch timing control is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs a single electromagnetic solenoid that serves multiple functions by sequentially controlling the drive devices of different cylinders. The solenoid acts as a universal controller that can displace lock pins in various cylinders at different timings, reducing the total number of solenoids needed while maintaining independent control capability.
3Reliability
If the mover is separated from the lock pin during valve lifting, then the reliability of valve operation is improved, but the control precision of valve timing is worsened
Solution Approach 1:
The patent employs self-locking surfaces (pushback surface and stopped surface) that are pre-configured on the input arm and lock pin. When the valve starts to lift, these surfaces automatically engage to lock the input arm and output arm in their respective positions, ensuring precise timing control without requiring continuous contact between the mover and lock pin.
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 allows for easy and reliable control of valve operation timing in the base circle phase, reducing costs by using a single electromagnetic solenoid to drive multiple cylinders, while maintaining effective switching performance.
Implementation Method 1
a drive device that displaces the lock pin to a lock position... includes a driving source being an electromagnetic solenoid
Implementation Method 2
a lost motion spring that brakes the freely swinging input arm when the lock pin is in the unlock position
Implementation Method 3
a return spring that displaces the lock pin to an unlock position
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
A variable valve mechanism of an internal combustion engine includes an input arm, an output arm, a lock pin, a drive device and a return spring of the lock pin, and a lost motion spring of the input arm. The input arm has in its rear end portion a pushback surface and a stopped surface. The lock pin has in its distal end portion a pushed-back surface and a stopping surface. The drive device includes a driving source and a mover that moves to push the lock pin when driven by the driving source. A driving force of the driving source is set so as to be smaller than a force with which the pushback surface pushes back the pushed-back surface as the lost motion spring causes the input arm to freely swing upward and be larger than load with which the return spring displaces the lock pin.