Hybrid Vehicle Torque Control Device for Engine Start Shock
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Solution Overview
Problem
Hybrid vehicles face challenges in balancing fuel efficiency and minimizing engine start shock, as setting motor running available torque by subtracting starting torque from the electric motor's upper limit torque can lead to inefficient fuel use and increased engine start shock, especially with large-capacity batteries, and insufficient drive torque when starting torque is diverted for running torque.
Innovation Solution
A control device for hybrid vehicles that notifies the driver of the motor running state using both running and starting torque, allowing maximum utilization of electric motor power while reducing engine start shock by adjusting torque output and securing starting torque only when necessary, utilizing multiple electric motors and differential mechanisms to optimize torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the motor running available torque is set by subtracting the starting torque from the upper limit torque of the electric motor, then the engine start shock is suppressed, but the fuel efficiency deteriorates and the motor running region is unnecessarily restricted
Solution Approach 1:
The patent dynamically adjusts the motor running available torque based on real-time battery state of charge (SOC). When SOC is high, the system allows motor running using even the starting torque, expanding the motor running region. When SOC is low, the system restricts motor running to preserve starting torque capability. This dynamic adjustment resolves the contradiction by adapting the torque allocation strategy to current system conditions rather than using a fixed conservative limit.
Solution Approach 2:
The patent changes the parameter of motor running available torque from a fixed value (upper limit torque minus starting torque) to a variable value that depends on battery SOC. This parameter change allows the system to optimize between fuel efficiency and start shock suppression by adjusting the available torque parameter according to battery charge levels, enabling fuller utilization of electric motor power when battery capacity permits.
2Reliability
If the motor running available torque is set by subtracting the starting torque from the upper limit torque of the electric motor, then the engine start reliability is improved, but the productivity of motor running is reduced
Solution Approach 1:
The system dynamically adjusts motor running availability based on battery SOC levels. When SOC is high, the system permits motor running even when using the starting torque, significantly expanding motor running capability and productivity. When SOC is low, the system maintains conservative torque allocation to ensure reliable engine start. This dynamic strategy resolves the contradiction by adapting reliability assurance to current battery capacity rather than always restricting motor running.
Solution Approach 2:
The patent transforms the motor running available torque from a static parameter to a dynamic parameter that varies with battery SOC. This parameter change enables the system to maximize motor running productivity when battery capacity allows while maintaining sufficient starting torque reserve for reliable engine start when needed, thus resolving the contradiction between reliability and productivity.
3Loss of energy
If the starting torque is diverted as the running torque to extend motor running capability, then the fuel efficiency improves, but the drive torque becomes insufficient at engine start resulting in increased engine start shock
Solution Approach 1:
The system dynamically determines whether to allow motor running using the starting torque based on real-time battery SOC. When SOC is high, the system permits using the starting torque for motor running, accepting increased start shock risk but achieving better fuel efficiency. When SOC is low, the system restricts motor running to preserve starting torque. This dynamic decision-making resolves the contradiction by adapting torque allocation to current battery capacity rather than always conserving starting torque.
Data Source
AI summary
A control device of a hybrid vehicle includes an electric motor outputting a running torque at the time of motor running and a starting torque at engine start, in a state of the motor running using even the starting torque, the control device being configured to give a notification of the state to a driver when a charging capacity is smaller than a first predetermined value, and to start an engine when the charging capacity is smaller than a second predetermined value which is smaller than the first predetermined value.