Hybrid Engine Cranking via Segmented Electric Machines
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Solution Overview
Problem
Hybrid vehicles with engines and electric machines face limitations due to the electric machine's limited capacity, which restricts its ability to accelerate beyond low speeds without engine assistance, leading to reduced utility beyond starting the engine.
Innovation Solution
Implementing a method where the engine is started by two electric machines under different conditions, with one providing torque to the driveline during low demand and the other assisting during higher demand, allowing a smaller driveline integrated starter/generator to cover a broader torque range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single electric machine is used to start the engine and provide torque, then the electric machine must have high power output capacity, but this increases packaging constraints and weight
Solution Approach 1:
The single electric machine is segmented into two separate electric machines: a first electric machine (driveline integrated starter/generator) and a second electric machine (separate starter). Each machine is sized for its specific function, allowing the overall system to achieve high power capacity without requiring a single oversized heavy machine.
Solution Approach 2:
The first electric machine combines multiple functions: it serves as both a starter motor for engine cranking and as a driveline integrated starter/generator for providing torque to the driveline. This merging of functions allows the system to achieve versatility without requiring separate dedicated components for each function.
2Adaptability or versatility
If a single electric machine is used to both start the engine and provide driveline torque, then the machine must handle all conditions, but this limits its effectiveness beyond engine starting
Solution Approach 1:
The first electric machine is designed with multi-functionality, serving both as an engine starter and as a driveline torque provider. This universal design allows a single machine to handle multiple operational conditions, extending its adaptability beyond just engine starting to include vehicle acceleration and torque provision across a broader operating range.
3Reliability
If the driveline disconnect clutch is closed during engine starting, then the electric machine must accelerate the entire driveline, but this increases the torque demand on the electric machine
Solution Approach 1:
The second electric machine performs preliminary action by starting the engine independently before the driveline disconnect clutch is closed. This allows the engine to begin rotating and producing torque before being connected to the driveline, reducing the initial torque demand on the first electric machine and allowing for a more compact, lighter design.
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
This approach extends the driver demand torque range of the driveline integrated starter/generator, improves engine starting, and enables the engine to accelerate to the starter/generator speed before the driveline disconnect clutch is closed, enhancing vehicle performance and efficiency.
Implementation Method 1
starting an engine with a first electrical machine
Implementation Method 2
starting the engine with a second electrical machine
Implementation Method 3
driveline disconnect clutch is closed/open
Data Source
AI summary
Systems and methods for improving operation of a hybrid vehicle are presented. In one example, an engine may be started in one of two ways depending on operating conditions. In particular, the engine may be started via a lower power output electric machine or a higher power output electric machine.