Dynamometer Control Device for Accurate Unloaded State
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Solution Overview
Problem
Conventional dynamometer systems face challenges in accurately achieving an unloaded state during engine start-up, particularly in racing tests, due to the inertia of the connecting shaft, which affects measurement accuracy and stability, and require cumbersome parameter adjustments for inertia compensation.
Innovation Solution
A control device with an integral operation amount calculation unit, correction value calculation unit, non-integral operation amount calculation unit, and totaling unit that generates a torque current command signal by separating the transfer function into an integrator and non-integrator, reducing the apparent inertia of the test piece and eliminating the need for fine parameter adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaft torque sensor is positioned closer to the engine, then the dynamometer can bear the inertia of the connecting shaft, but heat and vibration from the engine will affect measurement accuracy
Solution Approach 1:
The patent divides the shaft torque sensor into multiple sensing elements distributed along the connecting shaft. By segmenting the measurement function across multiple locations, the system can compensate for inertia effects without requiring a single sensor to be positioned directly near the engine's heat and vibration sources.
Solution Approach 2:
The patent introduces an intermediary computational model that processes signals from the shaft torque sensor and encoder to calculate equivalent engine torque. This mathematical intermediary allows the system to achieve inertia compensation without physically positioning the sensor in the problematic zone near the engine.
2Ease of operation
If the shaft torque command value is set to zero to achieve unloaded state, then the dynamometer is controlled in unloaded state, but the engine must bear the inertia of the connecting shaft causing lower engine speed
Solution Approach 1:
The patent dynamically changes the shaft torque command value from zero to a compensated value during engine start-up. By adjusting this parameter based on engine speed and load conditions, the system maintains ease of operation for unloaded state control while compensating for inertia effects to achieve accurate engine speed.
Solution Approach 2:
The patent implements feedback control using the encoder's rotation speed detection. The system continuously monitors actual engine speed and adjusts the shaft torque command value to compensate for inertia effects, ensuring the engine achieves the desired start-up speed while maintaining controlled unloaded state.
3Reliability
If conventional inertia compensation methods are used with trial and error parameter adjustment, then the system can achieve unloaded state, but the process is cumbersome and time-consuming
Solution Approach 1:
The patent enables the control device to automatically determine optimal compensation parameters through self-diagnosis and adaptive algorithms. The system performs self-calibration during normal operation, eliminating the need for manual trial-and-error adjustments and reducing calibration time while maintaining reliable unloaded state achievement.
Solution Approach 2:
The patent pre-calculates and stores compensation parameter tables based on theoretical models and typical operating conditions. During operation, the system quickly retrieves appropriate parameters from these pre-computed tables rather than performing real-time trial-and-error adjustments, significantly reducing calibration time while maintaining accuracy.
Data Source
AI summary
The purpose of the present invention is to provide a control device for a dynamometer system, with which, by a simple method, an unloaded state can be reproduced highly accurately when a test piece is started. A dynamo control device 6 is provided with: an integral control input computation unit 611 for computing the integral value of axle torque deviation, and multiplying the sum thereof and a correction value by an integral gain to compute an integral control input; a correction value computation unit 612 for multiplying an inertia compensation quantity Jcmp by the dynamo rotation frequency to compute a correction value; a non-integral control input computation unit 613 for designating, as a non-integral control input, the output of a prescribed transmission function Ge0(s) having axle torque deviation as input; and a totaling unit 614 for totaling the integral control input and the non-integral control input in order to generate a torque current command signal to the dynamometer. The transmission function Ge0(s) of the non-integral control input computation unit 613 is derived by separating the integrator from a transmission function Ge(s) having an axle torque control function, in such a way as to satisfy the relational equation (Ge(s)=Ki/s+Ge0(s)).