Exhaust Valve Coupling with Spring Preload for Rattle Reduction
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Solution Overview
Problem
Existing exhaust-gas valve systems face challenges with rattling noise and reduced torsional stiffness, leading to increased stress on actuators and gear wear, which affects reliability and lifespan.
Innovation Solution
A coupling device with a torsionally rigid retainer and an elastic element, featuring a slot for translational movement and a coil spring that provides a predetermined tensioning angle to reduce rattling and enhance torque transfer, while maintaining minimal deformation and compensating for misalignment and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct coupling between drive shaft and driven shaft is used, then device complexity is reduced, but manufacturing precision and alignment tolerance are worsened
Solution Approach 1:
The coupling device acts as an intermediary component between the drive shaft and driven shaft, incorporating tolerance compensation mechanisms that absorb manufacturing errors and thermal expansion without requiring direct precision alignment between the shafts
Solution Approach 2:
The coupling device allows for parameter changes in shaft positioning and orientation, accommodating variations in alignment through its mechanical design that compensates for deviations from ideal alignment conditions
2Reliability
If high torque is applied rapidly to reduce valve rattling, then reliability is improved, but stress on actuator and gear wear increases
Solution Approach 1:
The coupling device incorporates elastic elements that store energy and provide cushioning before high torque is applied, reducing the shock load on actuator components while maintaining the ability to deliver high torque when needed for valve positioning
3Temperature
If thermal expansion is compensated with flexible coupling, then temperature gradient tolerance is improved, but torsional stiffness is reduced
Solution Approach 1:
The coupling device is segmented into multiple functional elements including rigid and flexible components, allowing thermal expansion compensation in certain directions while maintaining torsional stiffness through the rigid structural segments
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 solution effectively reduces rattling noise, increases the lifespan of the actuator, and allows for higher torque application over a wider time frame, while maintaining structural integrity and compensating for assembly clearances.
Implementation Method 1
an elastic element (4), in particular a coil spring, comprising a coupling rod (45) which can be moved in the direction of the rotational axis and being biased in the direction of the rotational axis
Implementation Method 2
a torsionally rigid retainer (2) having an axially extending slot (25) in which the coupling rod (45) is received for translational movement of the rod parallel to the rotational axis in a direction circumferential relative to the rotational axis
Implementation Method 3
the driven shaft is subjected to significant thermal stress because of the temperature gradient
Implementation Method 4
Manufacturing errors can cause a drive shaft of the valve actuator and the driven shaft of the exhaust-gas valve to be misaligned
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a coupling device (1) for connecting a drive shaft (31) of an actuator to a driven shaft (51) of an exhaust-gas valve, the coupling device defining a rotational axis and comprising a torsionally rigid retainer (2) having an axially extending slot (25) which also extends circumferentially; a coupling rod (45) received in the slot for translational movement 4_1, 4_2) relative to the retainer (2) in the direction of the rotational axis; and an elastic element (4) biasing the coupling rod in the direction of the rotational axis and having one end fixed to the retainer; wherein the coupling rod is rotationally movable for a predetermined tensioning angle within the edges (27) of the slot (25) relative with regard to the retainer (2).