Front end motor-generator system and hybrid electric vehicle operating method
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. When the 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.
1. A hybrid electric arrangement for an internal combustion engine, comprising:
a motor-generator;
a torque transfer segment having a motor-generator end configured to receive the motor-generator and transfer torque between the motor-generator end and a coupling end of the torque transfer segment; and
an integrated switchable coupling configured to be co-axially located between the coupling end of the torque transfer segment and a front end of an engine crankshaft,
wherein the integrated switchable coupling includes an engine-side portion including a crankshaft vibration damper portion configured to be coupled to the engine crankshaft, a drive-side portion configured to be coupled to the torque transfer segment coupling end and to drive at least one engine accessory drive coupled to the drive-side portion, and a clutch arranged between the engine-side portion and the drive-side portion, the clutch being configured to selectively engage the engine-side portion with the drive-side portion,
the drive-side portion concentrically surrounds at least a portion of the clutch along a coupling rotation axis, and
a rotation axis of the motor-generator is parallel to and laterally offset from the coupling rotation axis.
2. The hybrid electric arrangement of claim 1 , wherein
the torque transfer segment is a gearbox including a motor-generator end gear configured to be coupled to the motor-generator and a coupling end gear configured to be coupled to the drive portion of the integrated switchable coupling, and
said gearbox gears are arranged to transfer torque between the motor-generator and the integrated switchable coupling.
3. The hybrid electric arrangement of claim 2 , wherein
the gearbox includes at least one intermediate gear arranged to transfer torque between the motor-generator end gear and the coupling end gear.
4. The hybrid electric arrangement of claim 3 , wherein
a reduction ratio of the gearbox is between 1:1 and 4:1.
5. The hybrid electric arrangement of claim 4 , wherein
a reduction ratio of the gearbox is approximately 2:1.
6. The hybrid electric arrangement of claim 1 , wherein
the motor-generator includes a front end motor-generator controller configured to control actuation of the switchable coupling actuator to switch between engaged and disengaged states.
7. The hybrid electric arrangement of claim 1 , further comprising:
a torque arm configured to be coupled between a housing of the torque transfer segment and one of the engine and a member coupled to the engine such that the torque transfer segment is rotationally fixed relative to an engine block of the engine.
8. The hybrid electric arrangement of claim 7 , wherein
the member is a portion of an engine support structure.