Hybrid Vehicle Engine Speed Limiting for Quick Firing Motoring Transition
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Solution Overview
Problem
The transition between firing and motoring operations in hybrid vehicles is not done quickly due to the lack of an upper limit rotational speed setting, leading to degraded acceleration responsiveness.
Innovation Solution
A control method for hybrid vehicles that sets an upper limit for the target rotational speed of the internal combustion engine during failures, allowing for quick transitions between firing and motoring operations by setting the target rotational speed to an on-failure upper limit rotational speed for firing and ensuring it is not higher than the on-failure fuel cut recovery rotational speed for motoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an upper limit rotational speed is not set when shifting into motoring operation from firing operation, then the engine can operate freely without speed restrictions, but transition between firing and motoring operation is not done quickly and acceleration responsiveness degrades
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the target rotational speed based on operational mode. When in firing operation, an upper limit rotational speed is set to prevent excessive speed buildup. When transitioning to motoring operation, this speed limit is released or adjusted, allowing the engine to quickly reach the desired speed for acceleration. This parameter adjustment resolves the contradiction by enabling both speed control during firing and rapid response during motoring operation.
2Reliability
If the engine rotational speed is not limited during failure, then the engine can maintain operational flexibility, but secondary failures may occur and acceleration responsiveness degrades
Solution Approach 1:
The patent implements dynamic rotational speed limiting based on failure detection. When a failure is detected in the firing operation, the control system dynamically adjusts the upper limit rotational speed to a safer value, preventing the engine from operating at high speeds that could cause secondary failures. This dynamic adjustment maintains reliability while allowing the engine to still function within safe parameters.
3Power
If the target rotational speed is set high during motoring operation, then acceleration performance is improved, but the risk of secondary failure increases during engine failure
Solution Approach 1:
The patent applies preliminary action by detecting engine failures before they can lead to secondary failures. When a failure is detected, the control system preemptively adjusts the upper limit rotational speed to a safer value. This preliminary protective action prevents the engine from reaching speeds that could cause secondary failures, while still allowing adequate acceleration performance within the adjusted speed limits.
Data Source
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AI summary
It is a control method of a hybrid vehicle that includes an engine (11) and an electrical power generation motor (12) that is connected with the engine (11) for controlling a rotational speed of the engine (11) to be a target rotational speed. When an failure with respect to the engine (11) is judged, an upper limit of a target rotational speed of a firing operation is set to a first upper limit rotational speed lower than an upper limit for a normal state. Further, a target rotational speed of a motoring operation is set to be not higher than the first upper limit rotational speed. It becomes possible to carry out transition between the firing operation and the motoring operation quickly.