Wastegate Actuator with Tilting Tappet Guide
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Solution Overview
Problem
Existing actuators for variable turbine geometry devices in exhaust gas turbochargers, such as pneumatic servo-drives, are not optimally suited for the specific requirements of wastegate operation, particularly in terms of heat resistance, adaptability, and compatibility with hinged mechanisms.
Innovation Solution
A rotary drive actuator that converts rotary motion into reciprocating motion through a threaded element and tappet system, allowing for tilting or pivoting movements with play in the guide, enabling efficient actuation of wastegates and variable turbine geometry devices, potentially eliminating the need for return springs and using cost-effective materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pneumatic servo-drives are used as actuators, then the actuation of wastegates and variable turbine geometry devices can be achieved, but the heat resistance and adaptability to hinged mechanisms are insufficient
Solution Approach 1:
The patent replaces the pneumatic servo-drive system with a mechanically actuated system comprising a threaded element that converts rotary motion into reciprocating motion of the tappet. This mechanical substitution eliminates the limitations of pneumatic systems regarding heat resistance and adaptability to hinged wastegate mechanisms, while maintaining reliable actuation functionality
Solution Approach 2:
The patent changes the fundamental operating parameter from pneumatic pressure-driven motion to mechanically-driven reciprocating motion through thread engagement. This parameter change enables the actuator to withstand higher temperatures and adapt to the pivoting motion requirements of hinged wastegates, resolving the contradiction between reliability under thermal stress and adaptability to different mechanism types
2Manufacturing precision
If a tappet is rigidly connected to the threaded element, then precise reciprocating motion can be achieved, but the ability to accommodate tilting or pivoting movements is lost
Solution Approach 1:
The patent introduces dynamic flexibility by allowing the tappet to tilt or pivot within guided constraints while maintaining reciprocating motion. The guide structure with web and broadened portions provides controlled play that accommodates the circular path motion of hinged wastegates, enabling both precise linear actuation and adaptive angular movement
Solution Approach 2:
The guide structure acts as an intermediary between the threaded element and the wastegate mechanism. It mediates the motion transmission by allowing controlled tilting of the tappet while maintaining the reciprocating motion generated by the threaded element, thus reconciling the conflict between motion precision and adaptability
3Manufacturing precision
If guide bushings are used to guide the tappet, then motion control is improved, but friction and wear increase
Solution Approach 1:
The patent replaces traditional guide bushings with a guide structure formed by webs and broadened portions that provide guidance through geometric constraints rather than sliding contact. This substitution reduces friction and wear while maintaining motion control, as the guidance is achieved through the configuration of the guide structure itself rather than through continuous contact with bushings
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 actuator provides improved heat resistance, adaptable stroke control, high actuating forces, low friction, and reduced wear, enabling precise control of wastegates and replacing pneumatic or vacuum actuators, with the ability to achieve non-linear force characteristics and efficient operation in a wide range of applications.
Implementation Method 1
A rotary drive (12) which firstly drives a threaded element (18) in rotation... A tappet (22) cooperates with the threaded element (18) and is in engagement with the threaded element (18) in such a manner that the rotary motion of the threaded element (18) is converted into a reciprocating motion of the tappet (22)
Data Source
AI summary
An actuator has a rotary drive and a threaded element for converting the rotary motion of the rotary drive into a reciprocating motion of a tappet connected to a hinged wastegate and/or to a variable turbine geometry device of an exhaust gas turbocharger. The tappet and/or an axle between the tappet and the threaded element is received in at least one guide comprising at least one web and allowing for at least a slight tilting or pivoting movement of the tappet in at least one direction. At least some play is present between the web and at least one broadened portion on the tappet and/or on the axle. Methods of actuating a wastegate and/or a variable turbine geometry device.