Actuator Calibration for Variable Geometry Turbine
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Solution Overview
Problem
The calibration of actuators for variable geometry turbines in turbochargers is complex and time-consuming, requiring manual alignment of the actuator output gear with the nozzle ring, which is challenging due to the confined space and limited travel range, leading to increased production and servicing times.
Innovation Solution
An automatic calibration method using a rotary sensor device with a sensor wheel and clutch mechanism that logs limit values to pre-align the actuator output shaft relative to the variable geometry element, allowing the actuator to operate within the sensor's rotational range, eliminating the need for complex calibration procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual calibration procedure is used to align actuator output gear with nozzle ring, then alignment precision is improved, but assembly time and operational complexity increase
Solution Approach 1:
The system performs self-calibration automatically. The microprocessor controls the actuator to move the nozzle ring to predetermined positions, the rotary sensor detects these positions, and the microprocessor stores the corresponding output gear angles. This eliminates the need for manual alignment procedures while maintaining precision.
Solution Approach 2:
The manual mechanical alignment process is replaced with an automated electronic control system. The microprocessor and rotary sensor work together to automatically determine and store calibration data, substituting the manual mechanical alignment operation with an automated electromechanical system.
2Manufacturing precision
If manual calibration procedure is used to align actuator output gear with nozzle ring, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-calibration automatically. The microprocessor controls the actuator to move the nozzle ring to predetermined positions, the rotary sensor detects these positions, and the microprocessor stores the corresponding output gear angles. This eliminates the need for manual alignment procedures while maintaining precision.
Solution Approach 2:
The manual mechanical alignment process is replaced with an automated electronic control system. The microprocessor and rotary sensor work together to automatically determine and store calibration data, substituting the manual mechanical alignment operation with an automated electromechanical system.
3Volume of moving object
If actuator and nozzle ring are mounted in confined space, then space utilization is improved, but calibration operation difficulty increases
Solution Approach 1:
The system performs self-calibration automatically. The microprocessor controls the actuator to move the nozzle ring to predetermined positions, the rotary sensor detects these positions, and the microprocessor stores the corresponding output gear angles. This eliminates the need for manual alignment procedures while maintaining precision.
Solution Approach 2:
The rotary sensor acts as an intermediary measurement device. Instead of requiring direct visual alignment or manual adjustment, the rotary sensor detects the angular position of the output gear and provides this information to the microprocessor, which then uses it to establish the correct calibration. This intermediary sensing mechanism enables calibration in confined spaces where manual operations would be difficult.
4Length of moving object
If limited travel range of actuator is used, then device compactness is improved, but calibration accuracy difficulty increases
Solution Approach 1:
The rotary sensor provides feedback on the angular position of the actuator output gear throughout the limited travel range. The microprocessor uses this feedback to accurately determine the gear angle at each end of the travel range and stores these values for calibration. This feedback mechanism enables precise calibration despite the limited travel range by continuously monitoring and recording positional data.
Solution Approach 2:
The manual mechanical alignment process is replaced with an automated electronic control system. The microprocessor and rotary sensor work together to automatically determine and store calibration data, substituting the manual mechanical alignment operation with an automated electromechanical system.
Data Source
AI summary
A variable geometry turbine of the kind used in a turbocharger has a variable geometry element such as a nozzle ring or an annular array of swing vanes that is operated by an actuator. The actuator has an output shaft coupled to a transmission mechanism for moving the variable geometry element. A rotary sensor device coupled to the output shaft of the actuator has a sensor wheel with a stop, slip clutch mechanism and a rotary position sensor. The device converts movement of the actuator output shaft into rotation of the wheel and the sensor generates an output signal representative of the rotary position of the wheel to provide a value indicative of the position of the variable geometry element. The actuator is calibrated to the position of the variable geometry element by rotating the sensor wheel in a first rotational direction until the variable geometry element reaches the first limit position, then rotating the sensor wheel in a second direction until the variable geometry element reaches the second limit position. The value of the output signal is logged at one of these positions as a limit value. The sensor wheel is allowed to declutch in the event that it encounters the stop in either direction of rotation. The output signal is monitored and the limit value is deducted to determine the position of the variable geometry element.