Hybrid Regenerative Braking Control Under Battery Charge Restriction
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Solution Overview
Problem
In hybrid vehicles, motoring during restricted battery charging leads to fouling of sensors downstream of the engine due to oil discharge, which decreases measurement accuracy and emission performance.
Innovation Solution
A regenerative control device that restricts battery charging by redirecting regenerative power to the engine's power generation motor generator for motoring, while maintaining regenerative braking power through combustion operation, preventing oil discharge and sensor fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the motor generator is driven as an electric motor to forcibly rotate the stopped engine (motoring) to consume regenerative power, then regenerative braking can be performed while restricting battery charging, but oil is discharged into the exhaust pipe and LAF sensor fouling occurs
Solution Approach 1:
The control device performs preliminary action by controlling the power generation motor generator to operate in power generation mode before oil discharge and sensor fouling occur. By generating power during the motoring period, the engine rotates faster which promotes oil vaporization and prevents oil from adhering to the LAF sensor, thereby preventing the harmful effect before it occurs
Solution Approach 2:
The control device changes the operational parameters of the power generation motor generator by controlling it to operate in power generation mode during motoring. This parameter change causes the engine rotation speed to increase, which in turn changes the thermal state of the combustion chamber and exhaust gases, leading to oil vaporization rather than discharge, thus preventing sensor fouling
2Object-affected harmful factors
If the power generation motor generator is controlled to perform motoring while advancing valve timing and adjusting throttle opening, then lubricating oil can be inhibited from being sucked into the intake system, but the device complexity increases
Solution Approach 1:
Instead of trying to prevent oil suction into the intake system by controlling valve timing and throttle opening, the invention inverts the approach by controlling the power generation motor generator to operate in power generation mode during motoring. This causes the engine to rotate faster, creating positive pressure that prevents oil from being suctioned into the intake system through a different mechanism, thereby solving the problem with simpler control
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 sensor fouling by ensuring regenerative power is consumed by the engine, maintaining accurate emission measurements and improved driving feel by managing regenerative braking and combustion operations.
Implementation Method 1
A LAF (linear air-fuel ratio) sensor that detects the air-fuel ratio of the exhaust gas is placed on an exhaust pipe from the engine. The LAF sensor is capable of detecting the ratio between air and fuel in the exhaust gas as a continuous value
Implementation Method 2
a traveling motor generator where a power generation function is added to the traveling motor
Implementation Method 3
the motor generator coupled to the engine is driven as an electric motor to forcibly rotate the stopped engine (motoring)
Implementation Method 4
combustion in the cylinder is not performed
Data Source
Figure 1
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Figure 4
AI summary
A regenerative control device (10) for a hybrid vehicle (20) includes a regenerative braking power control unit (1308) prohibiting or limiting execution of first regenerative braking to charge the battery (108) with power generated by the regenerative power generation of the traveling motor generator (106) during deceleration when it is determined that it is necessary to restrict charging of the battery (108). The regenerative braking power control unit (1308) causes both second regenerative braking to transmit rotary driving power to the engine (102) by rotating the power generation motor generator (104) by the power generated by the regenerative power generation, and combustion operation in which fuel is supplied to the engine (102) and the fuel is burned to generate the rotary driving power at the engine, to be executed, under condition where the execution of the first regenerative braking is prohibited or limited.