Aircraft Generator CVT Warm-Up Control at Low-Temperature Start
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Solution Overview
Problem
In aircraft power generation systems, the warm-up time is prolonged due to increased heat capacity and reduced temperature increasing effect when the CVT operates at a maximum deceleration position during low-temperature start-ups, especially when the CVT size increases to accommodate wider speed change ranges.
Innovation Solution
A power generation controller that positions the speed change element of the hydraulic transmission at the acceleration side during low-temperature start-ups, continuously outputting an acceleration-side drive signal to increase the oil temperature quickly, and includes a temperature condition determining section to ensure reliable oil temperature monitoring and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CVT operates at maximum deceleration position during low-temperature start-up, then the power generator is protected from excessive speed, but the warm-up time is prolonged due to increased heat capacity and reduced stirring loss
Solution Approach 1:
The control device performs preliminary warming-up action by positioning the speed change element at the acceleration side before normal operation begins. This preliminary action increases the oil temperature in advance, so that when normal operation starts, the hydraulic actuator is already in a suitable temperature state, eliminating the need for prolonged warm-up at maximum deceleration position.
2Adaptability or versatility
If the CVT size is increased to accommodate wider speed change range, then the speed change width is improved, but the heat capacity increases and warm-up time is prolonged
Solution Approach 1:
The control device dynamically adjusts the operating position of the speed change element based on temperature conditions. During low-temperature start-up, it positions the element at the acceleration side to increase warm-up efficiency, whereas in normal conditions it can operate at the deceleration side for power generator protection. This dynamic adjustment allows the larger CVT to warm up efficiently without compromising its wide speed change capability.
3Adaptability or versatility
If the maximum reduction ratio is increased to increase deceleration width, then the speed change range is improved, but the rotational frequency after deceleration becomes low and temperature increasing effect decreases
Solution Approach 1:
The control device implements periodic or conditional action by switching between two distinct operating modes: during low-temperature conditions, it operates in warming-up mode with the speed change element at the acceleration side to generate heat; once the temperature condition is met, it switches to normal operating mode with the element at the deceleration side for power generator protection. This periodic switching between modes allows the system to achieve both wide deceleration range and adequate warm-up effect.
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
This approach shortens the warm-up time by rapidly increasing the oil temperature during low-temperature start-ups, preventing excessive power generation or idle power transmission, and ensuring stable operation by maintaining the speed change element at the maximum acceleration position.
Implementation Method 1
Speed change control of the CVT is performed by a hydraulic actuator
Implementation Method 2
rotational power extracted from an aircraft engine is changed in speed by a transmission so as to have an appropriate rotational frequency
Implementation Method 3
the rotational power is then transmitted to a power generator
Data Source
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AI summary
A power generation controller of an aircraft includes a low-temperature start-up control section and a power generation control section. When it is determined that an oil temperature of a hydraulic actuator configured to change an operation position of a speed change element of a hydraulic transmission satisfies a predetermined low-temperature condition when starting up an aircraft engine, the low-temperature start-up control section sets a power generator to a power non-generating state and controls the hydraulic actuator such that the speed change element is positioned at an acceleration side of a median in a speed change range. When it is determined that the oil temperature satisfies a predetermined low-temperature start-up completion condition, the power generation control section sets the power generator to a power generating state and controls the hydraulic actuator in accordance with a rotational frequency of the aircraft engine.