Hybrid Vehicle Drive Control System for Uphill Grade Torque Management
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Solution Overview
Problem
Hybrid vehicles experience backward coasting on uphill grades due to the delay in delivering drive torque when shifting from engine to motor mode, as the clutch and transmission interposed between the motor and drive wheels cause a lag in torque transmission.
Innovation Solution
A drive control system that includes a controller to determine engine stall or torque failure, shifting the vehicle to a motor-driven mode by delivering torque from the motor to the second drive wheels while disengaging the engagement device, and optionally adjusting the transmission speed ratio to ensure prompt delivery of drive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clutch and geared transmission are interposed between the motor and drive wheels, then the motor can be activated promptly upon detection of abnormal operation, but it takes time until drive torque is delivered to the drive wheels
Solution Approach 1:
The patent extracts the engagement device from the torque transmission path between the motor and drive wheels. When engine stall is detected, the controller disengages the engagement device to create a direct connection, eliminating the delay caused by the clutch and transmission. This allows motor torque to be delivered directly to the drive wheels without the time lag associated with engaged transmission components.
2Force
If the engagement device is engaged to transmit engine torque, then torque can be delivered to drive wheels, but backward coasting occurs when engine torque cannot be delivered on uphill grades
Solution Approach 1:
The controller continuously monitors engine operation status and detects engine stall conditions. When engine stall is detected, the feedback mechanism triggers immediate disengagement of the engagement device and activation of the motor to prevent backward coasting. This closed-loop control ensures the system responds reliably to changing conditions and maintains forward motion on uphill grades.
Solution Approach 2:
The system performs preliminary detection of engine stall conditions and prepares for immediate torque delivery by the motor. The controller is configured to detect engine stall and automatically switch to motor-driven mode before backward coasting can occur, ensuring proactive prevention rather than reactive correction.
3Reliability
If the motor is activated to propel the vehicle on uphill grades, then backward coasting is prevented, but the clutch and transmission cause delay in torque delivery
Solution Approach 1:
The system dynamically changes the torque transmission configuration based on operating conditions. During normal operation, the engagement device connects the engine to the drive wheels through the transmission. When engine stall is detected on uphill grades, the system dynamically reconfigures by disengaging the engagement device and activating the motor, creating a direct torque path that is both fast and reliable for preventing backward coasting.
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
Prevents backward coasting by quickly delivering drive force to the wheels through the motor, reducing the risk of vehicle movement backward due to delayed torque transmission, especially on uphill grades.
Implementation Method 1
a motor connected to the first drive wheels or a pair of second drive wheels. The hybrid vehicle is propelled by torque generated by at least one of the engine and the motor
Implementation Method 2
a generator that translates an output power of the engine to an electric power to be delivered to the motor
Data Source
AI summary
A drive control system for a hybrid vehicle configured to prevent backward coasting on an uphill grade even when an engine torque cannot be delivered to drive wheels. When the hybrid vehicle is propelled by delivering engine torque to rear wheels on an uphill grade, the drive control system determines an occurrence of a failure in which the torque cannot be delivered from the engine to the rear wheels. If the occurrence of the failure is determined, the drive control system executes a hill hold control to deliver torque to establish a required drive force from a motor to front wheels while disengaging an engagement device.