Front end motor-generator system and hybrid electric vehicle operating method

Abstract

A system and method are provided for hybrid electric internal combustion engine applications in which a motor-generator, a narrow switchable coupling and a torque transfer unit therebetween are arranged and positioned in the constrained environment at the front of an engine in applications such as commercial vehicles, off-road vehicles and stationary engine installations. The motor-generator is preferably positioned laterally offset from the switchable coupling, which is co-axially-arranged with the front end of the engine crankshaft. The switchable coupling is an integrated unit in which a crankshaft vibration damper, an engine accessory drive pulley and a disengageable clutch overlap such that the axial depth of the clutch-pulley-damper unit is nearly the same as a conventional belt drive pulley and engine damper. The front end motor-generator system includes an electrical energy store that receives electrical energy generated by the motor-generator when the coupling is engaged. Whenthe coupling is disengaged, the motor-generator may drive the pulley portion of the clutch-pulley-damper to drive the engine accessories using energy returned from the energy store, independent of the engine crankshaft.

Description

technical field [0001] The present invention relates to hybrid electric vehicles, and more particularly to a system for selectively coupling a hybrid power generation and storage system with an internal combustion engine. The invention further relates to a method of operating the system, including a method of operating the system in a manner that prioritizes engine accessory speeds. Background technique [0002] Hybrid electric vehicles having an internal combustion engine combined with a motor-generator and an electrical energy storage system have become the focus of considerable interest in the automotive field, especially in the passenger car field. The development of hybrid electric vehicle systems has only recently begun to cause extreme stress in commercial and off-road vehicles (e.g., trucks and buses in vehicle classes 2-8), in earth-moving equipment and railway applications, and in stationary internal combustion engine powerplants. big interest. [0003] Hybrid el...

AI Technical Summary

Problems solved by technology

This approach adds significantly to vehicle weight, cost, and wiring harness and control system line length and complexity, potentially negating any fuel economy or emissions reductions provided by removing engine accessory loads from the engine

[0007] State-of-the-art hybrid electric vehicle systems have a number of disadvantages that hinder their adoption in applications such as commercial vehicles

These include: the engineering difficulties associated with trying to scale up hybrid powertrain components to handle the very high torque output of a large engine (typically a high torque output diesel engine); the interdependence of engine and motor-generator operation, as these components are either Integral to the rear of the engine, or directly on the driveline (i.e., the engine and motor-generator must be together); and when not operating a vehicle engine or operating a separate on-board auxiliary power unit (“APU”) (for example, a dedicated self-contained internal combustion unit or a dedicated battery pack containing multiple conventional batteries and associated support equipment) "hotel" loads (e.g. nighttime climate control and 120 volt power requirements in sleeper compartments of commercial vehicle tractors)

These APUs are very expensive (typically several thousand dollars), heavy and require considerable space on an already space constrained vehicle

In the case of fuel burning APUs, they also have the further disadvantage of potential hazards associated with open flames and the production of carbon monoxide (which can enter the sleeper compartment during driver rest periods), and in the case of all-electric APUs, they also have A further disadvantage that the vehicle's engine may not return sufficient energy for extended periods of time to meet all of the vehicle's accessory requirements when the vehicle's engine is off

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