Hybrid Vehicle Engine Start Control via Motor-Generator Speed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid vehicles face challenges in starting the engine efficiently in neutral mode, particularly at cold temperatures, as existing systems struggle to maintain engine startability when the engine is cold, such as at −30° C.
Innovation Solution
A control system for a hybrid vehicle that includes first and second planetary gear sets, motor-generators, clutches, and brakes, where the system is configured to rotate the engine to a predetermined speed by controlling the rotational speed of the motor-generators using specific formulas to ensure smooth engine starting, even in cold conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is started in neutral mode using conventional methods, then the system structure remains simple, but the engine starting performance deteriorates at cold temperatures (−30° C.)
Solution Approach 1:
The control system performs preliminary actions by rotating the engine to a predetermined speed using the first and second motor-generators before actual engine combustion starts. This preliminary rotation ensures the engine is ready for combustion even in cold conditions, addressing the startability issue without requiring structural changes to the transmission system.
Solution Approach 2:
The invention changes operational parameters by controlling the rotational speeds of the first and second motor-generators to specific values (first predetermined speed and second predetermined speed respectively). By adjusting these speed parameters, the system achieves reliable engine starting in neutral mode at cold temperatures without modifying the physical structure.
2Reliability
If the engine is rotated to predetermined speed using motor-generators, then engine starting performance is improved, but the control system complexity increases
Solution Approach 1:
The first and second motor-generators serve multiple functions: they act as motors during engine starting, as generators during regenerative braking, and as speed control mechanisms during neutral mode operation. By making these components multi-functional, the system achieves improved engine starting performance without adding dedicated starting equipment, thus limiting the increase in system complexity.
Solution Approach 2:
The controller continuously monitors the rotational speeds of the first and second motor-generators and adjusts their operation to maintain the predetermined speeds required for engine starting. This feedback control ensures reliable starting performance while using the existing motor-generator control infrastructure, avoiding the need for completely separate starting control systems.
3Stability of the object's composition
If the first and second motor-generators are controlled to rotate the engine, then the engine reaches target speed stably, but the control precision requirements increase
Solution Approach 1:
The planetary gear set acts as an intermediary mechanism between the first and second motor-generators and the engine. By controlling the motor-generators to rotate at predetermined speeds, the planetary gear set naturally distributes and combines their rotational outputs, providing stable engine rotation without requiring extremely precise synchronization between the two motor-generators.
Solution Approach 2:
The control system maintains the rotational speeds of the first and second motor-generators at predetermined values that create a balanced operational state. This equipotential approach ensures that both motor-generators contribute equally and stably to engine rotation, reducing the need for high-precision differential speed control while achieving stable target speed.
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 effectively starts the engine in neutral mode and ensures stable reach of target speed, securing startability even at colder temperatures, thereby improving engine starting performance.
Implementation Method 1
a first and second motor/generator... operate/control the first motor-generator and the second motor-generator to rotate the engine at a predetermined rotational speed
Implementation Method 2
The first brake may be configured to apply friction to the first ring gear to reduce the rotational speed of the first ring gear, and the second brake may be configured to apply friction to the second ring gear to reduce the rotational speed of the second ring gear
Data Source
AI summary
Disclosed is a control system and method for controlling starting of an engine in a hybrid vehicle. More specifically, a controller is implemented that confirms first and second brake and the first and second clutch are released so that the system is in a neutral condition, confirm that the engine is stopped, and control the first motor-generator and the second motor-generator to rotate the engine at a predetermined rotational speed to start the engine.