Hybrid Vehicle Drive Force Control System for Brake Torque Management
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Solution Overview
Problem
Hybrid vehicle drive force control systems face a reduction in maximum brake force when electrical input to the battery is restricted, limiting braking performance due to restricted engine speed and reduced regenerative torque.
Innovation Solution
A control system that manages the selection of operating modes by restricting the first mode when input power to the battery is below a threshold, ensuring the engine speed is maintained at a predetermined level to maximize brake force, and utilizing regenerative torque from the second motor to enhance braking, while adjusting throttle and fuel supply to optimize brake torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine speed is restricted to limit damage on rotary members of the power split mechanism, then the reliability of the power split mechanism is improved, but the maximum engine brake torque is restricted
Solution Approach 1:
The system dynamically switches between high mode and low mode based on battery input power conditions. In high mode, the engine speed can be higher to provide maximum brake torque. In low mode, the engine speed is restricted to protect the power split mechanism. This dynamic adaptation allows the system to optimize between reliability and braking force based on real-time conditions.
Solution Approach 2:
The system changes the operating parameters (engine speed limits, mode selection) based on the battery input power conditions. When battery input power is restricted, the system switches to low mode with lower engine speed limits to prevent damage to the power split mechanism while maintaining sufficient braking capability through the second motor.
2Force
If the mode is shifted from high mode to low mode to increase braking force, then the brake force is improved, but the electric power available for the second motor is reduced
Solution Approach 1:
The control system continuously monitors battery input power conditions and provides feedback to determine mode selection. When battery input power is sufficient, the system operates in high mode to maximize electric power availability. When battery input power is restricted, the system switches to low mode to maintain braking force while adapting to the reduced electric power conditions.
3Use of energy by moving object
If the first motor operates at reduced speed in low mode, then the electric consumption of the first motor is reduced, but the brake torque of the second motor is restricted
Solution Approach 1:
The system changes the operating parameters (engine speed, mode selection) based on battery input power conditions. When battery input power is restricted, the system switches to low mode with lower engine speed limits to prevent damage to the power split mechanism while maintaining sufficient braking capability through the second motor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system prevents a significant reduction in maximum brake force by optimizing engine speed and regenerative torque distribution, ensuring consistent braking performance even with limited battery input power.
Implementation Method 1
execute a regeneration control to deliver a regenerative torque resulting from operating the second rotary machine as a generator to the output member
Implementation Method 2
an engine brake control to deliver a brake torque resulting from a power loss of the engine to the output member
Implementation Method 3
an engine brake torque established by a friction torque and a pumping loss of the engine
Data Source
Figure 1
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Figure 3
AI summary
A control system for hybrid vehicles to prevent a reduction in a brake force when an electrical input to a battery (47) is restricted. A controller (48) is configured to execute a regeneration control to deliver a regenerative torque resulting from operating second motor (7) as a generator to the drive wheels (1L, 1R), and an engine brake control to deliver a brake torque resulting from a power loss of an engine (5) to the output member (18). The controller (48) is further configured to select an HV-Lo mode according to whether an input power (Win) allowed to accumulate in the battery (47) is smaller than a threshold power (W1).