Power Transmission Device with Dual Locking Pistons
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Solution Overview
Problem
Existing power transmission devices for variable valve trains in internal combustion engines lack a simple and reliable method for changing valve lift, leading to inefficiencies and complexities in valve operation.
Innovation Solution
A power transmission device featuring a rocker arm or rocker arm design with a main body, actuating piston, and dual locking pistons that allow for selective switching between two valve lifts, enabling two-stage valve lift variability and secure locking mechanisms to ensure fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power transmission device is used, then the structure is simple, but the valve lift cannot be reliably changed
Solution Approach 1:
The invention introduces a movable locking piston that can dynamically switch between locked and unlocked positions to enable or disable actuating piston movement, allowing the system to adapt between fixed and variable valve lift states. This dynamic mechanism ensures reliable valve lift changing while maintaining structural simplicity.
Solution Approach 2:
The locking piston serves as an intermediary element between the actuating piston and the valve train. By controlling whether the actuating piston can move, the locking piston reliably switches between two valve lift positions without requiring complex control systems.
2Reliability
If a single locking mechanism is used, then the device is simple, but fail-safe operation cannot be ensured
Solution Approach 1:
The invention incorporates a spring element that pre-loads the locking piston against the locking surface. This beforehand cushioning ensures that the locking piston maintains positive engagement with the locking surface under all operating conditions, preventing accidental disengagement and ensuring fail-safe operation.
Solution Approach 2:
The spring-loaded locking piston creates a dynamic locking mechanism that automatically maintains locking force despite variations in operating conditions such as pressure changes or thermal expansion, ensuring reliable fail-safe operation without adding excessive complexity.
3Ease of operation
If the actuating piston can move freely, then valve lift adjustment is simple, but secure positioning cannot be maintained
Solution Approach 1:
The locking piston transitions between two distinct states: locked and unlocked. In the locked state, it securely positions the actuating piston at a specific valve lift position. In the unlocked state, it allows free movement for adjustment. This dynamic switching mechanism provides both ease of operation and secure positioning.
Solution Approach 2:
The locking piston acts as an intermediary that controls the freedom of movement of the actuating piston. When engaged, it restricts movement to maintain secure positioning; when disengaged, it allows free movement for adjustment, thus providing both security and ease of operation.
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 device enables reliable and simple adjustment of valve lift, reducing complexity and improving engine efficiency by allowing two different valve lift profiles and ensuring secure piston positioning, thus enhancing engine performance and reducing operational risks.
Implementation Method 1
an actuating piston (20), in particular a hydraulic one, which is provided in the receptacle (16) such that it can be moved back and forth between a first position and a second position along the longitudinal axis
Implementation Method 2
a first, in particular hydraulic, locking piston (22), which is reciprocable in a radial direction with respect to the longitudinal axis between a third position in which the first locking piston (22) locks the actuating piston (20) in the first position
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a power transmission device (10), in particular a rocker arm or tappet, for establishing an operative connection between a camshaft (72) and a gas exchange valve (12). The power transmission device (10) has a main body (14) with a receptacle (16) extending along a longitudinal axis (A). The power transmission device (10) has an actuating piston (20) which is reciprocally movable between a first position and a second position along the longitudinal axis (A) in the receptacle (16). The power transmission device (10) has a contact element (28) for actuating the gas exchange valve (12), which is in operative connection with the actuating piston (20).The power transmission device (10) has a first locking piston (22) which is provided in the receptacle (16) and is movable back and forth in a radial direction with respect to the longitudinal axis (A) between a third position, in which the first locking piston (22) locks the actuating piston (20) in the first position, and a fourth position, in which the first locking piston (22) releases a movement of the actuating piston (20) between the first position and the second position.