Hybrid Vehicle Control Device for Fixed Gear Ratio and Torque Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hybrid vehicle control devices experience unintended gear shifts when the motor/generator's rotational speed exceeds a predetermined limit, leading to transitions to different gear stages against the driver's intention, failing to meet high-load travel requests effectively.
Innovation Solution
A control device with a rotational speed limit setting and control mechanism that fixes the gear ratio by the driver's intention, allowing the motor/generator to output torque within a set rotational speed limit, ensuring the assist and power generation requests are met while maintaining the selected gear stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rotational speed limit is set to exceed the motor/generator's upper rotational speed limit, then the driver's high-load travel request can be reflected, but the motor/generator cannot carry out torque output effectively
Solution Approach 1:
The rotational speed limit is made dynamic rather than fixed. The control device adjusts the rotational speed limit based on the actual rotational speed and torque output requirements of the motor/generator, allowing the system to adapt between meeting driver requests and maintaining effective torque output capability
Solution Approach 2:
The rotational speed limit parameter is changed from a static value to a variable that exceeds the upper rotational speed limit when conditions permit, enabling the system to reflect driver's high-load travel requests while the motor/generator can still operate effectively within its torque output capabilities
2Reliability
If the gear shift stage transitions automatically when motor/generator rotational speed exceeds the limit, then the motor/generator can maintain operational limits, but the gear ratio cannot be fixed by the driver's intention
Solution Approach 1:
The control device continuously monitors the rotational speed and torque output request of the motor/generator, and adjusts the rotational speed limit accordingly. This feedback mechanism ensures that the gear shift stage remains fixed according to driver selection while the rotational speed limit adapts to maintain motor/generator operational reliability
Solution Approach 2:
The rotational speed limit is made dynamic to accommodate both the fixed gear ratio selected by the driver and the operational requirements of the motor/generator, resolving the conflict between automatic gear shifting and driver intention
3Power
If the rotational speed limit is reduced to meet motor/generator torque output requirements, then effective torque output is achieved, but the driver's high-load travel request cannot be fully reflected
Solution Approach 1:
The rotational speed limit parameter is adjusted based on real-time conditions. When the motor/generator can carry out torque output, the limit is set to reflect the driver's high-load travel request. When torque output capability is compromised, the limit is reduced to maintain effective power delivery
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An assist request or a power generation request can be met while reflecting the high-load travel request of the driver. A control device for a hybrid vehicle comprises, in the drive system: an engine (Eng); a motor/generator (MG); an automatic transmission (AT) in which the gear ratio can be fixed by the driver's intention; and drive wheels (RL, RR). The control device comprises an assist traveling mode and an engine generation traveling mode as hybrid modes in which the engine (Eng) and the motor/generator (MG) are drive sources. The control device is provided with: a rotational speed limit setting unit (411) which sets a value that exceeds the upper rotational speed limit, at which the motor/generator (MG) can carry out a torque output, as the rotational speed limit (La) of the engine-motor rotational speed (Nem), and a rotational speed limit control unit (413) for reducing the rotational speed limit (La) to the rotational speed limit (Lb) at which the motor/generator (MG) can carry out a torque output, when the engine-motor rotational speed (Nem) has reached the rotational speed limit (La) and there is a torque output request of the motor/generator (MG).