Patent Application
20180215247
The present disclosure relates to a vehicle that may utilize a vehicle battery and motor, in conjunction with an engine, to drive power to the wheels.
A hybrid vehicle is known to have an internal combustion engine and a battery working in conjunction with a motor, which can provide kinetic energy to the driveline of the hybrid vehicle. Torque and power flow may be sent to the rear wheels by both the motor and/or the engine via a drive shaft and half shafts for the respective rear wheels. Torque and power flow may also be sent from the rear wheels to both the motor and/or the engine via half shafts and the driveshaft.
A first illustrative embodiment discloses a vehicle comprising an electric motor configured to drive power to rear wheels of the vehicle. The vehicle also includes a mechanical disconnect configured to engage, when closed, a plurality of half shafts corresponding to the rear wheels and a drive shaft coupled to a differential, and to engage, when open, the drive shaft but not the plurality of half shafts.
A second illustrative embodiment discloses an electric vehicle comprising a differential including a first input configured to receive power from an engine via a driveshaft and a second input configured to receive power from a motor. The electric vehicle also includes a clutch in driveable communication with the differential and configured to, in an open position, permit power flow from the motor to the driveshaft and preclude power flow from the motor to rear wheels, and to, in a closed position, permit power flow from the motor to the driveshaft and rear wheels.
A third illustrative embodiment discloses a vehicle comprising a rear differential including a first input adjacent a transmission that is in drivable communication with an engine via a driveshaft that is connected to a second input of the rear differential. The vehicle also includes an electric motor in drivable communication with the rear differential via the transmission, and configured to drive power to first and second rear wheels of the vehicle via first and a second half shafts respectively. The vehicle further includes one or more mechanical disconnects located at the first and second half shafts configured to drive the first and second rear wheels respectively when closed, and to engage a drive shaft connected to the engine, but not the first and second half shafts, when open.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Some hybrid architectures (e.g. P3) include a motor that is found after the transmission, driving the rear wheels by summing an electric-motor-torque with an internal combustion engine (ICE) torque before the differential. In such architecture, the traction motor may not be able to be utilized to charge a hybrid vehicle battery while the vehicle is stationary, without disconnecting the drive train from the wheels. Considering the substantial amount of torque on this path and the required hardware and controls complexity, a mechanical disconnect may be avoided.
Referring to
The engine 14 and the M/G 18 are both drive sources for the HEV 10. The engine 14 generally represents a power source that may include an internal combustion engine such as a gasoline, diesel, or natural gas powered engine, or a fuel cell. The engine 14 generates an engine power and corresponding engine torque that is supplied to the M/G 18 when a disconnect clutch between the engine 14 and the M/G 18 is at least partially engaged. The M/G 18 may be implemented by any one of a plurality of types of electric machines. For example, M/G 18 may be a permanent magnet synchronous motor. Power electronics condition direct current (DC) power provided by a battery to the requirements of the M/G 18, as will be described below. For example, power electronics may provide three phase alternating current (AC) to the M/G 18.
When a disconnect clutch is at least partially engaged, power flow from the engine 14 to the M/G 18 or from the M/G 18 to the engine 14 is possible. For example, the disconnect clutch may be engaged and M/G 18 may operate as a generator to convert rotational energy provided by a crankshaft and M/G shaft into electrical energy to be stored in the battery associated with the motor. The disconnect clutch can also be disengaged to isolate the engine from the remainder of the powertrain such that the M/G 18 can act as the sole drive source for the HEV 10. A Shaft extends through the M/G 18. The engine 14 is continuously drivably connected to the shaft (e.g. driveshaft 36), whereas the M/G 18 is drivably connected to the shaft 36 only when a disconnect clutch is at least partially engaged.
The M/G 18 is connected to a torque converter (e.g. in a motor/generator-transmission 19) via a shaft. The M/G 18 may include its own transmission system 19 distinct from The torque converter is therefore connected to the engine 14 when the disconnect clutch is at least partially engaged. The torque converter may include an impeller fixed to shaft 36 and a turbine fixed to a transmission input shaft. The torque converter thus provides a hydraulic coupling between shaft 30 and a transmission input shaft. The torque converter transmits power from the impeller to the turbine when the impeller rotates faster than the turbine. The magnitude of the turbine torque and impeller torque generally depend upon the relative speeds. When the ratio of impeller speed to turbine speed is sufficiently high, the turbine torque is a multiple of the impeller torque. A torque converter bypass clutch (also known as a torque converter lock-up clutch) may also be provided that, when engaged, frictionally or mechanically couples the impeller and the turbine of the torque converter, permitting more efficient power transfer. The torque converter bypass clutch may be operated as a launch clutch to provide smooth vehicle launch. Alternatively, or in combination, a launch clutch similar to disconnect clutch may be provided between the M/G 18 and gearbox for applications that do not include a torque converter or a torque converter bypass clutch. In some applications, disconnect clutch is generally referred to as an upstream clutch and launch clutch (which may be a torque converter bypass clutch) is generally referred to as a downstream clutch.
As shown in the representative embodiment of
The powertrain may include an associated controller, such as a powertrain control unit (PCU). While illustrated as one controller, the controller may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that the powertrain control unit and one or more other controllers can collectively be referred to as a “controller” that controls various actuators in response to signals from various sensors to control functions such as starting/stopping engine 14, operating M/G 18 to provide wheel torque or charge battery, select or schedule transmission shifts, etc. Controller may include a microprocessor or central processing unit (CPU) in communication with various types of computer readable storage devices or media. Computer readable storage devices or media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM is a persistent or non-volatile memory that may be used to store various operating variables while the CPU is powered down. Computer-readable storage devices or media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller in controlling the engine or vehicle.
The controller communicates with various engine/vehicle sensors and actuators via an input/output (I/O) interface (including input and output channels) that may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing, and/or conversion, short-circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process particular signals before being supplied to the CPU. As generally illustrated in the representative embodiment of
Control logic or functions performed by controller may be represented by flow charts or similar diagrams in one or more figures. These figures provide representative control strategies and/or logic that may be implemented using one or more processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various steps or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Although not always explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending upon the particular processing strategy being used. Similarly, the order of processing is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic may be implemented primarily in software executed by a microprocessor-based vehicle, engine, and/or powertrain controller, such as controller. Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers depending upon the particular application. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media having stored data representing code or instructions executed by a computer to control the vehicle or its subsystems. The computer-readable storage devices or media may include one or more of a number of known physical devices which utilize electric, magnetic, and/or optical storage to keep executable instructions and associated calibration information, operating variables, and the like.
To drive the vehicle with the engine 14, a disconnect clutch is at least partially engaged to transfer at least a portion of the engine torque through the disconnect clutch to the M/G 18, and then from the M/G 18 through the torque converter and gearbox. The M/G 18 may assist the engine 14 by providing additional power to turn the shaft 30. This operation mode may be referred to as a “hybrid mode” or an “electric assist mode.”
To drive the vehicle with the M/G 18 as the sole power source, the power flow remains the same except the disconnect clutch isolates the engine 14 from the remainder of the powertrain. Combustion in the engine 14 may be disabled or otherwise OFF during this time to conserve fuel. A traction battery may transmit stored electrical energy through wiring to power electronics that may include an inverter, for example. The power electronics may convert DC voltage from the battery 20 into AC voltage to be used by the M/G 18. A controller may command the power electronics to convert voltage from the battery 20 to an AC voltage provided to the M/G 18 to provide positive or negative torque to the shaft 30. This operation mode may be referred to as an “electric only” or “EV” operation mode.
In any mode of operation, the M/G 18 may act as a motor and provide a driving force for the powertrain. Alternatively, the M/G 18 may act as a generator and convert kinetic energy from the powertrain into electric energy to be stored in the battery. The M/G 18 may act as a generator while the engine 14 is providing propulsion power for the vehicle 10, for example. The M/G 18 may additionally act as a generator during times of regenerative braking in which torque and rotational (or motive) energy or power from spinning wheels 42 is transferred back through the gearbox, torque converter, (and/or torque converter bypass clutch) and is converted into electrical energy for storage in a battery.
It should be understood that the schematic illustrated in
During regenerative braking, it may be advantageous for the control system of the HEV 10 to coordinate the operation of the powertrain and braking systems to maximize fuel economy while also accounting for vehicle drivability. This may be accomplished by adapting the control systems to consider a wheel torque schedule, which may include anti-jerk control, during a regenerative braking event. Failing to consider the wheel torque schedule during regenerative braking may lead to torque holes during braking because the brake control is not aware of the actual status of the powertrain. This may also results in the transmission unnecessarily capacitating the torque converter to handle more negative torques when the powertrain has not actually requested so, causing waste of energy.
The first clutch 201 and second clutch 203 may be a dog clutch, such as a single friction dog clutch, at the ring/half-shaft interface or a one-way clutch. A single clutch may be configured to selectively engage with a ring to the half-shafts 44. In yet another embodiment, the first clutch 201 and second clutch 203 may be an electronically controlled hydraulic rocker one-way clutch. Meshing gearing elements may have a fixed gear ratio configured to define an overdrive speed and torque relationship between the engine and the output shaft when the clutch is engaged. A controller may be configured to selectively command the clutch to engage or disengage in response to various operating conditions. Other gearing arrangements that impose an overdrive speed relationship between the engine and output shaft may, of course, be used. An alternative pinion location for the electrical motor 18 input to the differential 40 may also be located on a ring of the clutch.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
