Hybrid Vehicle Throttle Control for High-Altitude Torque Response
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Solution Overview
Problem
Hybrid electric vehicles experience poor acceleration at high altitudes due to delayed engine torque increase after clutch re-engagement, caused by reduced intake air amount at low atmospheric pressure, leading to sluggishness and potential emission issues.
Innovation Solution
A vehicle controller adjusts the throttle opening degree based on atmospheric pressure to maintain a constant intake air amount, ensuring smooth and quick acceleration by controlling the engine torque during mode switching, particularly at high altitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the throttle opening degree is kept small after clutch re-engagement to prevent abrupt torque change, then the torque stability is improved, but the engine torque increase is delayed at high altitudes due to reduced intake air amount
Solution Approach 1:
The throttle opening degree is dynamically adjusted based on atmospheric pressure conditions. At high altitudes with low atmospheric pressure, the throttle opening degree is increased compared to sea level conditions, allowing sufficient intake air amount even with the throttle partially closed. This dynamic adjustment resolves the contradiction by adapting the throttle control strategy to environmental conditions, enabling both torque stability and adequate torque increase speed.
Solution Approach 2:
The control strategy changes the throttle opening degree parameter according to atmospheric pressure. By increasing the throttle opening degree at high altitudes, the system compensates for the reduced air density, ensuring that the engine receives adequate intake air during the critical period after clutch re-engagement. This parameter change resolves the contradiction between maintaining torque stability and achieving sufficient torque increase speed in low atmospheric pressure environments.
2Speed
If the throttle opening degree is increased to improve engine torque response at high altitudes, then the acceleration performance is improved, but the intake air amount control precision is reduced
Solution Approach 1:
The control strategy applies different throttle opening degree settings for different atmospheric pressure conditions. Instead of using a single fixed throttle control strategy, the system implements local quality control by adjusting the throttle opening degree based on the specific environmental conditions (high altitude vs. sea level). This resolves the contradiction by optimizing the throttle control for each operating condition, achieving both good acceleration performance and adequate intake air control precision.
Solution Approach 2:
The system performs preliminary adjustment of the throttle opening degree based on predicted atmospheric pressure conditions before the clutch re-engagement. By pre-setting an appropriate throttle opening degree based on atmospheric pressure, the system ensures that the engine is ready to respond quickly to clutch engagement while maintaining control over the intake air amount. This preliminary action resolves the contradiction between acceleration performance and control precision.
Data Source
AI summary
An electronic control unit includes processing circuitry. A hybrid electric vehicle has an electric traveling mode, in which the hybrid electric vehicle travels with a system clutch disengaged and an engine in a stopped state, and a hybrid traveling mode, in which the hybrid electric vehicle travels with the system clutch engaged and engine operating. The processing circuitry is configured to control, when the traveling mode is switched from the electric traveling mode to the hybrid traveling mode, a throttle opening degree of the engine at the time of completion of engagement of the system clutch in accordance with the atmospheric pressure such that a constant intake air amount is obtained regardless of the level of the atmospheric pressure.