Hybrid Vehicle Engine Start Timing for Stable Driving Torque
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Solution Overview
Problem
Conventional hybrid vehicles experience torque fluctuations and degraded running feelings due to battery voltage declines, leading to inefficient engine starting and excessive torque increases when the driver accelerates.
Innovation Solution
The hybrid vehicle includes an engine and motor that operate independently, with a control device that starts the engine if a predetermined battery output condition is met for a certain time, even without driver input, to stabilize driving torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is started when battery voltage declines to a lower limit voltage, then the battery electric power consumption can be suppressed, but the driving torque fluctuates and the running feeling is degraded
Solution Approach 1:
The control device starts the engine in advance when the battery output state continues for a predetermined time or more, before the battery voltage actually declines to the lower limit voltage. This preliminary engine start prevents subsequent torque fluctuations that would occur if the engine were started later when voltage had already dropped, thus maintaining driving torque stability while still managing battery power consumption effectively.
2Force
If the driver depresses the accelerator pedal strongly to increase driving torque, then the driver-demanded torque increases, but the driving torque becomes excessively large and the running feeling is further degraded
Solution Approach 1:
The control device continuously monitors the battery output state and uses this feedback to determine the optimal timing for engine start. By detecting when the battery output state persists for a predetermined time, the system proactively starts the engine to maintain stable driving torque, preventing the need for aggressive accelerator pedal depression and avoiding excessive torque increases that would degrade running feeling.
3Power
If the engine is started when battery voltage is low, then the battery power can be maintained, but the rapid torque increment causes the driver to rapidly ease the accelerator pedal, reducing usability
Solution Approach 1:
The engine is started in advance based on the predetermined time condition of battery output state, before battery voltage becomes critically low. This timing prevents rapid torque increments that would occur with delayed engine start, allowing the driver to maintain steady accelerator pedal depression and enjoy smooth, predictable vehicle acceleration, thereby enhancing usability.
Data Source
AI summary
The disclosed hybrid vehicle (1) includes: an engine (2) and a motor (3) that operate independently of each other; a battery (5) that stores electric power to drive the engine (2) and the motor (3); and a control device (10) that controls operating states of the engine (2) and the motor (3). If a condition A is satisfied when the motor (3) is operating but the engine (2) is not operating, the control device (10) starts the engine (2). The condition A is that a state where a battery output of the battery (5) is a predetermined value or more continues for a predetermined time or more.