CN112585049A - Front-end motor-generator system and hybrid electric vehicle operation method - Google Patents

Abstract

A system and method for hybrid electric internal combustion engine applications is provided in which a motor-generator, a narrow switchable coupling and a torque transfer unit therebetween are arranged and positioned in a constrained environment in front of an engine in applications such as commercial vehicles, off-road vehicles and stationary engine installations. The motor generator is preferably located laterally offset from a switchable coupling arranged coaxially with the forward end of the engine crankshaft. The switchable coupling is an integrated unit in which the crankshaft vibration damper, the engine accessory drive pulley, and the disengagable 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 storage that receives electrical energy generated by the motor-generator when the coupler is engaged. When the coupling is disengaged, the motor-generator may drive the pulley portion of the clutch-pulley-damper to use energy returned from the energy storage to drive the engine accessories, independent of the engine crankshaft.

Description

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

Technical Field

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 speed.

Background

Hybrid electric vehicles having an internal combustion engine combined with a motor generator and an electrical energy storage system have become a considerable focus of attention in the automotive field, and particularly in the passenger vehicle field. The development of hybrid electric vehicle systems has only recently begun to be of great interest in commercial and off-road vehicles (e.g., trucks and buses in vehicle classes 2-8), in earth moving equipment and railroad applications, and in stationary internal combustion engine powerplants.

Hybrid electric technology offers many advantages, including improved fuel efficiency, reduced internal combustion engine emissions and vehicle noise, to help meet government regulatory requirements, improved vehicle performance, and lower fleet operating costs. These advantages benefit in large part from the ability of the hybrid electric system to recapture energy that would otherwise be wasted (e.g., mechanical energy from braking, otherwise dissipated to the environment as thermal energy) and return the captured energy at another time when needed (e.g., to power vehicle components rather than using an internal combustion engine as a power source or to assist vehicle propulsion).

Typically, the motor-generator of a hybrid electric vehicle is arranged independently of the internal combustion engine (e.g., using a separate electric motor to drive and recover energy from the front wheels while the engine provides propulsion power to the rear wheels), or is coupled to the engine, for example incorporated into the "rear" of the engine (i.e., the end of the engine where the flywheel is located) or between the engine and the drive train of the wheels. This "behind the engine" position allows the motor-generator device to transfer torque directly to the driveline and wheels of the vehicle, and to be driven directly by the driveline, for example during a regenerative braking event. Examples of the latter include flywheel motor generators, in which the flywheel of a conventional engine is modified to serve as the motor generator rotor and a concentrically mounted stator is located around the flywheel, and a separate electric motor disposed between the engine and the drive wheels, such as the so-called "two-mode hybrid" transmission provided by General Motors in the 2009 GMC Silverado pickup, which houses two electric Motors for vehicle propulsion and electrical power generation.

Another form of adding a motor generator to an internal combustion engine is to use a so-called starter-generator. The method directly couples the electric motor to the engine to serve as both a generator (a function traditionally performed by conventional belt-driven alternators) and an engine starter, thereby reducing the weight and cost of a duplex (dual) alternator and starter motor. Such starter-generator arrangements are particularly useful in so-called engine start stop systems, which shut down the engine during vehicle stops to save fuel and reduce idle emissions. The starter-generator is located behind the engine (e.g., a suitably designed flywheel motor-generator may also serve as a starter) and is mounted at the engine front end where it can drive a belt that is directly coupled to the engine crankshaft. An example of the latter system is the "belt alternator starter" system offered by General Motors as an option for the 2007 model Saturn Vue sport utility vehicle. These systems are difficult to accommodate with large engines, such as commercial vehicle diesel engines, because the electric motor must be larger to handle the higher torque requirements of these heavy duty engines, such as starting and operating various components (e.g., engine cooling fans can require up to 50 kilowatts of power, requiring a large amount of torque to drive the load carried by the fan). Moreover, the belt drives in such extended systems need to have the ability to transmit large levels of torque, which may not be possible, or at least not practical, because thicker and wider drive belts and pulleys sufficient to handle the torque requirements may be larger and heavier than their automotive counterparts, and therefore their weight, size, and/or cost are high.

Another method of electrification is to use separate electric motors to separately drive energy-consuming engine and vehicle accessories, such as air conditioning compressors, power steering pumps, air compressors, engine cooling fans, and coolant pumps, to reduce fuel consumption by removing accessory loads from the engine. This approach significantly increases vehicle weight, cost, and wiring harness and control system wiring length and complexity, potentially offsetting the fuel economy or emission reduction effects provided by removing engine accessory loads from the engine.

Prior art hybrid electric vehicle systems have a number of drawbacks that have prevented their adoption in applications such as commercial vehicles. These include: engineering difficulties associated with attempting to scale up hybrid powertrain components to handle the very high torque output of large engines (typically high torque output diesel engines); interdependence of engine and motor-generator operation, as these components are either integral with the engine rear or directly on the drive train (i.e., the engine and motor-generator must rotate together even when rotation of one or the other of the engine and motor-generator is not required or even detrimental to overall vehicle operating efficiency); and "hotel" loads (e.g., nighttime climate control and 120 volt electrical power requirements in commercial vehicle tractor sleeper compartments) cannot be met independently without operating the vehicle engine or without operating a separate on-board auxiliary power unit ("APU") (e.g., a dedicated self-contained internal combustion engine set or a dedicated battery pack containing multiple conventional batteries and associated support equipment). These auxiliary power units are very expensive (typically several thousand dollars), heavy and require considerable space on vehicles that have been space constrained. In the case of fuel-fired APUs, they also have the further disadvantage of potential hazards associated with open flames and the production of carbon monoxide (which may enter the sleeper compartment during driver rest), and in the case of fully electric APUs, they also have the further disadvantage of not returning sufficient energy for a long time to meet all accessory requirements of the vehicle when the vehicle engine is off.

Disclosure of Invention

Overview of the main front end motor generator system components.

The present invention addresses these and other problems by providing a hybrid electric vehicle system located at the front end of the engine, wherein the motor-generator is arranged in a manner that requires little or no extension of the length of the front of the vehicle. As used in this specification, the "front end" of an engine is the end opposite the end from which the torque output produced by the engine is transmitted to a primary torque consumer (e.g., a transmission and driveshaft of a vehicle or a load of a stationary engine device, such as a pump drive). Typically, the rear end of the engine is where the engine flywheel is located and the front end is where components such as engine driven accessories (e.g., air conditioning and compressed air compressors, engine cooling fans, coolant pumps, power steering pumps) are located. While the following discussion focuses primarily on commercial vehicle embodiments in which the engine crankshaft is aligned with the longitudinal axis of the vehicle, the invention is not limited to front-engine, longitudinally aligned engine applications, but may also be used with transversely mounted engines (including transversely mounted engines located at the front or rear of a vehicle) that may also have a highly space-limited environment in the region near the end of the engine opposite the end of the flywheel.

Preferably, the front end motor generator system of the present invention has a motor generator located in the front region of the engine, laterally offset to the rotational axis side of the engine crankshaft. The motor-generator is preferably supported on a torque transfer section (also referred to as a "drive unit"), such as a narrow depth single reduction parallel shaft gearbox, which is arranged with its input rotation axis coaxial with the engine crankshaft. The motor generator is preferably located behind the torque transfer section in a space between the engine and an adjacent longitudinal vehicle chassis frame member or in front of the torque transfer section in a space below the vehicle coolant radiator. The present invention is not limited to these locations for the motor-generator, but may be located anywhere in the area near the front of the engine, as long as the torque transmitting section on which it is mounted may be aligned with the engine crankshaft axis of rotation.

Preferably, the torque transfer section also provides a suitable speed ratio (e.g., a 2: 1 ratio) between its input and output to better adapt the engine and motor-generator speeds to each other, i.e., to provide an increase in speed from the engine to the motor-generator and a decrease in speed from the motor-generator output. The torque transfer section may be a gearbox with gears or another drive arrangement (e.g., a chain belt) on the motor-generator side of a disengageable coupling (discussed further below) between the engine crankshaft and the torque transfer section, which transfers torque between the motor-generator end and the engine end of the torque transfer section. The torque transfer section has an axially narrow profile to allow it to be housed between the front of the engine crankshaft and any component in front of the engine (e.g., the engine's coolant radiator).

An important feature of the present invention is that the motor-generator exchanges torque with the engine crankshaft via a switchable coupling (i.e., disengageable) between the torque transfer section and the front end of the crankshaft. The switchable coupling includes an engine-side portion directly coupled to the engine crankshaft, a drive portion engageable with the engine-side portion to transfer torque therebetween, and an engagement device (preferably an axially-actuated clutch between the drive portion and the engine-side portion). Unlike conventional crankshaft dampers, which are traditionally separate elements secured to the crankshaft as dedicated crankshaft vibration suppression devices, the engine-side portion of the coupling includes a crankshaft vibration damper (hereinafter "damper"). This arrangement enables torque to be transferred between the accessory drive, the motor-generator, and the engine in a flexible manner, for example, having the accessory drive driven by a different torque source (e.g., the engine and/or the motor-generator), having the engine be the torque source that drives the motor-generator as a generator, and/or having the motor-generator coupled to the engine and operating as a motor to serve as an auxiliary vehicle propulsion torque source.

Particularly preferably, the switchable coupling is an integrated clutch-pulley-damper unit with a clutch between the engine-side damper part and the drive part. The drive side portion includes a drive flange configured to be coupled to an engine end of the torque transmitting section, the drive flange further including one or more pulley segments on an outer circumference thereof. The preferred construction also provides for all three components of the pulley, clutch and damper to be concentrically arranged, with at least two of these elements partially overlapping each other along their axes of rotation. This arrangement results in a disengageable coupling with greatly minimized axial depth to facilitate installation of the FEMG in a space-constrained environment ahead of the engine. The axial depth of the coupling can be further minimized by reducing the axial depth of the clutch, pulley and damper to a point where the drive pulley extends concentrically around all, or at least substantially all, of the clutch and engine side damper portions of the coupling.

Alternatively, one or more of the three clutch, pulley and damper portions may be arranged coaxially with the other portions, but not axially overlapping the other portions, as desired to accommodate the particular front end arrangement of the engine from different engine suppliers. For example, in engine applications where the belt drive is not aligned with the damper (i.e., the damper does not have a damper around its outer periphery)Belt drive grooves, e.g. in some

In an engine arrangement), the belt driving surface of the pulley portion of the coupling need not axially overlap the damper. In other applications, there is a belt driving surface on the outer circumference of the damper and another belt driving surface on a pulley mounted in front of the damper, for example in some Detroit applications

In an engine, the coupling that will be used in place of the original damper and pulley may be provided with two belt driving surfaces on a pulley that extends axially on the damper (i.e., the damper axially overlaps substantially all of both the damper and the clutch), or a belt driving surface on the outer circumference of the damper may be retained (e.g., driving an engine accessory that is never disconnected from the crankshaft, such as an engine coolant pump), while another belt driving surface is located on a pulley member that extends axially on the clutch.

Although in the following description reference is made to connecting the damper part of the switchable coupling to the engine crankshaft, the switchable coupling engine connection is not limited to being connected to the crankshaft, but may be connected to any rotatable shaft of the engine accessible from the front of the engine, which is capable of transmitting torque between the engine and a motor generator, for example a crankshaft driven intermediate shaft or a suitably designed camshaft with a front accessible shaft end. Further, although reference is made in the following description to connecting a portion of the switchable coupling having the damper to the engine crankshaft, the engine-side connection of the switchable coupling is not limited to the portion having the damper but includes a portion (e.g., a plate member) having no damper, which is capable of being connected to the rotatable engine shaft while supporting an engine-side portion of the disengageable coupling (e.g., an engine-side clutch plate that holds the switchable coupling opposite to the pulley-side clutch plate).

The FEMG motor-generator is preferably electrically coupled to an electrical energy storage unit (also referred to herein as an "energy storage"). The energy storage preferably comprises two batteries suitable for high capacity long term energy storage, such as lithium chemistry based batteries capable of storing and returning large amounts of energy at moderate charge/discharge rates, and super-capacitors capable of receiving and releasing electrical energy at very high charge/discharge rates that may exceed the capability of lithium batteries to safely handle. This combination provides an energy store that can work with the motor-generator to absorb and/or discharge current for short periods of time above normal (i.e., over a wider range of motor-generator input or output loads that the battery unit can handle), while also providing battery-based long-term energy storage and return at lower charge and discharge rates.

Although the present disclosure is primarily directed to the use of an FEMG system in vehicular applications, particularly commercial vehicular applications, the FEMG system is also well suited for use in stationary engine installations (e.g., backup diesel generators), off-road engine applications such as self-propelled construction equipment, and other engine applications where the available space to provide hybrid power capability at the front of the engine is limited.

Overview of FEMG Driving of Engine Accessories

Engine accessories are traditionally belt driven, directly driven by the engine crankshaft, via a drive pulley bolted to the crankshaft. In the FEMG system, the engine accessories are also driven by the pulley, but the pulley is located on the motor-generator side of the clutch-pulley-damper (the "drive portion" identified above). The pulley of the clutch-pulley-damper unit is driven by the engine when the coupling is engaged, or by the motor generator when the coupling is disengaged. When the pulley-clutch-damper is disengaged, all of the engine accessories driven by the pulley are disconnected from the engine, removing their respective power requirements from the engine. This isolation of the accessories from the engine reduces fuel consumption while the engine is running. Further, since the accessories can be independently driven by the FEMG motor-generator via the torque transfer section while the coupling is disengaged, when the vehicle is at rest, the engine can be shut down or operated idle with little or no parasitic load to save fuel and reduce emissions.

Further system efficiency improvements may be obtained when the clutch-pulley-damper is disengaged, since the operating speed of the motor-generator may be varied as needed to operate one or more engine accessories at a speed that provides increased operating efficiency, while if doing so, reducing overall energy consumption, then other engine accessories will operate at sub-optimal efficiency speeds.

Preferably, to improve system efficiency, some or all of the engine accessories may be provided with a separate drive clutch (on/off or variable slip engagement) to enable selective engine accessory operation while other engine accessories are shut off or operated at a reduced speed. The combination of the ability to operate the motor-generator at variable speeds and the ability to selectively engage, partially engage, and disengage each of the accessory clutches provides an opportunity to customize the accessory energy consumption to that required only by the current operating conditions, further increasing overall system efficiency.

Alternatively, when one engine accessory has a high power input requirement that must be met under current vehicle operating conditions, the motor-generator may be driven at a speed that ensures that the engine accessory with the highest requirement can proceed as needed, while the other accessories operate at less than optimal efficiency or are disconnected from the motor-generator drive by their respective clutches (if equipped).

Preferably, the FEMG controller, discussed further below, executes an algorithm that evaluates factors such as engine accessory operating efficiency data and current vehicle operating state information (e.g., energy storage state of charge ("SOC"), engine torque output requirements, coolant temperature) to select a combination of vehicle operating parameters (e.g., engine accessory clutch engagement alone, accessory operating speed, pulley speed and engagement state of the clutch-pulley-damper, speed and torque output of the motor-generator) to determine a compromise configuration of coupling and clutch engagement state and component operating speed that meets the operating requirements of the vehicle while reducing fuel and energy usage. For example, while providing superior overall system efficiency is achieved by operating the motor-generator at a speed and torque output that places as many engine accessories as possible in or near their peak operating efficiency state, certain vehicle needs (such as the need to operate a high torque-demanding engine cooling fan to control engine coolant temperature) may cause the FEMG to control motor-generator speed and/or torque output to ensure that the particular requirements are met, and then operate other individual engine accessories driven by the clutch-pulley-damper in a manner that is as efficient as possible under the current vehicle operating environment.

Similarly, if the current demand for vehicle propulsion torque from the engine is high (and the state of charge of the energy storage allows), the FEMG controller may control the clutch-pulley-damper to switch to the engaged state and command the motor-generator to provide supplemental torque to the engine crankshaft to increase the overall output of propulsion torque, even though this may result in the engine accessories being driven at less than optimum efficiency because their speed is dependent on crankshaft speed.

Overview of the use of a dynamoelectric machine

When operating conditions permit, the clutch-pulley-damper may be engaged such that the motor-generator may recover mechanical energy from the engine crankshaft (i.e., recover mechanical energy transferred to the motor-generator from the wheels through the driveline to the engine crankshaft). For example, the clutch may be engaged during a deceleration event to allow the motor-generator to function as a generator in a regenerative braking mode that also saves cost in reducing brake pad or brake shoe wear and saves fuel consumption by minimizing brake air usage and associated compressed air consumption, which in turn reduces air compressor usage and energy consumption. The clutch may also be engaged when there is any other "negative torque" requirement, such as when it is necessary to provide a retarding force to minimize undesirable vehicle acceleration due to gravity when the vehicle is descending a slope.

When the disengageable pulley-clutch-damper is engaged and operating conditions permit, the motor-generator may be operated as a torque-producing motor to provide supplemental torque to the engine crankshaft, thereby increasing the total torque output supplied to the vehicle driveline to increase vehicle acceleration.

Another use of the motor generator is as a main engine starter, eliminating the need for a heavy duty dedicated starter motor. In this mode of operation, the clutch-pulley-damper is engaged to allow the motor-generator torque to be transferred directly to the engine crankshaft. This use of the motor generator is well suited to the operating characteristics of the motor generator as it is capable of producing very high torque outputs starting at zero rpm and is almost instantaneous. The fast reaction time and ability to run multiple times without overheating of the motor-generator make the FEMG system the best choice as a main engine starting motor in a fuel efficient engine "stop/start" system where the engine is started and stopped multiple times per day. Short restart reaction time capability is highly desirable in stop/start system applications where it is well known that any substantial delay in the automatic engine restart by the driver in response to the driver's request to resume movement (typically, a request generated by the release of the vehicle brake pedal after the traffic signal turns green) is indicative of an dissatisfaction. For example, drivers often find a delay of one second or more before the engine starts and the vehicle begins to move to a minimum of annoyance if not completely unacceptable.

Alternatively, the motor generator of the FEMG system may operate as an engine starter in cooperation with a pneumatic starter motor that converts stored compressed air pressure to a mechanical torque output (pneumatic starters are typically lighter and less costly than conventional electric starter motors). The weight and cost of the FEMG system may be improved with a combined FEMG/pneumatic start arrangement, as the supplemental torque output of the pneumatic starter may allow the FEMG motor-generator size to be reduced in the event that the highest expected torque demand on the FEMG motor-generator is associated with an engine start (particularly a cold engine start). In this case, the FEMG motor-generator may be sized to meet the next lower requested torque request (e.g., the highest expected torque request from the highest requested engine accessory combination), where the pneumatic starter may be used to provide the additional engine cranking torque required, which is higher than the additional engine cranking torque provided by the smaller FEMG motor-generator.

The motor generator may also be driven by the engine through the clutch of the engaged clutch-pulley-damper in a manner that does not require the engine to be equipped with a heavy dedicated alternator to supply operating voltage for the 12 vdc circuit of a typical vehicle, such as the vehicle lighting circuit, electronics module, and power supply for the 12V-driven driver comfort features (heating seats, sleeper compartment electrical, etc.). In a FEMG system, the required 12V power supply can be easily provided by a voltage converter that reduces the operating voltage of the energy storage (approximately 300-400 volts) to the 12 volts required by the vehicle circuitry. Thus, the electric energy generated by the motor-generator provides a 12V source of electric energy for charging the energy storage, which allows the elimination of a conventional engine-driven alternator. Storing a large amount of energy in the energy storage also creates an opportunity to remove additional weight and cost from the vehicle by reducing the number of 12V batteries needed to meet various needs of the vehicle. For example, a vehicle that may traditionally have four separate 12V batteries may only require a single 12V battery and energy storage.

Similarly, the voltage converter may be used to supply 120 volt ac directly to the vehicle, for example to a sleeper compartment for appliances or air conditioning use, or to an attached trailer to operate a trailer device such as a refrigeration unit (the refrigeration unit preferably having a trailer connection to the CAN system of the vehicle for tractor central monitoring and control of trailer accessories). The FEMG system may also eliminate the need to equip the vehicle with an expensive and heavy internal combustion engine driven auxiliary power unit to support vehicle operation when the engine is off for long periods of time if the energy storage is designed to provide sufficient storage capacity. For example, during nighttime driver breaks, the APU will no longer be needed to power the sleeper compartment air conditioning unit.

The FEMG may also act as an active damper to resist the rapid torque reversal pulses ("torque ripple") sometimes encountered during various load, speed, and environmental conditions. In this application, the FEMG control module will receive a signal from a vehicle sensor indicating that a torque ripple is present and output a command to the motor generator to generate a timed anti-torque pulse to cancel the driveline torque reversal pulse. Such active damping based on the FEMG motor-generator helps protect the driveline from mechanical damage caused by high stresses due to rapid changes in torque load and improves driver comfort by eliminating rapid acceleration/deceleration transmitted through the vehicle chassis to the vehicle cabin.

Overview of FEMG controller Programming and operating methods

In a preferred embodiment, the FEMG controller, preferably in the form of an electronic control module, monitors a plurality of vehicle signals, including signals available on the vehicle CAN and/or SAE J1939 bus network (if the vehicle is so equipped). One of the signals may be a state of charge (SOC) indication from a battery monitoring system that monitors a state of charge of the energy storage, or the like. The control module may be programmed, for example, to identify three state of charge levels, namely, a minimum charge level (e.g., 20% state of charge), an intermediate charge level (e.g., 40% state of charge), and a maximum charge level (e.g., 80% state of charge). The control module may also be programmed to include the state of charge as a factor: determining when to engage and disengage the clutch of the clutch-pulley-damper, at what speed the motor-generator should operate, at what operating speed of some or all of the engine accessories driven from the pulley of the clutch-pulley-damper, what combination of vehicle component operation and operating parameters will improve overall vehicle operating efficiency while meeting the current operating requirements of the vehicle and meeting the requirements for safe vehicle operation (e.g., by operating the air compressor, maintaining at least a minimum required amount of air pressure in the vehicle pneumatic system compressed air storage tank, even if doing so would reduce the overall energy efficiency of the vehicle).

In one embodiment, the clutch of the clutch-pulley-damper may be engaged when the state of charge of the energy storage is below a minimum charge level, and the motor-generator controlled by the control module causes the motor-generator to generate electrical energy for storage. In this mode of operation, the motor generator is powered by the engine or by the wheels through the engine via the driveline. Once the state of charge is above the minimum charge level, the clutch of the clutch-pulley-damper may remain engaged until an intermediate charge level is reached, and the motor-generator is controlled to generate electrical energy only during braking, deceleration, or negative torque events. This mode allows the motor-generator to continue to charge the energy storage using mechanical energy not provided by the engine on an available basis, while minimizing the energy that the engine must provide for the motor-generator, thereby reducing fuel consumption.

In another mode of operation, once the intermediate charge level is reached, the control module may determine that the clutch-pulley-damper clutch may be disengaged and the motor-generator is acting as a motor to generate torque to drive the engine accessories without engine assist, i.e., the motor-generator becomes the sole source of driving energy for the engine accessories. In this mode, the motor generator draws stored electrical energy from the energy storage to generate torque for delivery to the pulley of the clutch-pulley-damper via the drive unit gearbox to drive engine accessories, such as an engine cooling fan and an air compressor of the pneumatic supply system. By disengaging the engine from the torque demand of the engine accessories, the engine may be operated at a lower parasitic torque load to reduce fuel consumption of the engine or to make more engine torque output available to propel the vehicle. Alternatively, when the motor generator may be operated in a motor mode to drive the engine accessories, the engine may be completely shut down, such as in stop-and-go traffic in a vehicle equipped with a start/stop system.

Between the intermediate charge level and the maximum charge level, the front end motor-generator control module continues to monitor vehicle operating conditions, and during braking, deceleration or negative torque events may take advantage of the opportunity to further charge the energy storage without using engine fuel by engaging the clutch of the clutch-pulley-damper and controlling the motor-generator to generate electrical energy. When charging during braking, a deceleration or negative torque event may occur at any time the energy storage is below the maximum charge level; in this embodiment, the use of engine fuel for charging above the intermediate charge level is avoided, reducing fuel consumption and improving overall efficiency.

At any point above the minimum charge level, the motor generator may operate as a motor to produce torque to be delivered to the engine crankshaft to supplement the torque output of the engine, thereby increasing the amount of torque available to propel the vehicle. Increasing torque output to the driveline may improve vehicle acceleration and provide additional benefits, such as improved fuel economy from fewer transmission shifts, and faster acceleration to cruising speeds (e.g., "skip shifts" where the motor-generator adds sufficient engine torque to allow one or more gear ratios to be transferred while the vehicle is accelerating, thereby reducing vehicle acceleration time and fuel consumption). Furthermore, in vehicles equipped with a pneumatic boost system ("PBS"), a system that injects compressed air into the engine intake in order to provide additional engine torque output very quickly, using nearly "instant start" torque assistance from the motor-generator as much as possible instead of using compressed air injection from the PBS system to produce additional engine torque output may reduce the use of compressed air, further reducing fuel consumption and component wear (consumption and wear associated with additional air compressor operation to supplement the compressed air supply).

Once the FEMG control module determines that the maximum charge level has been reached and therefore no further input of electrical energy into the energy storage is required, the control module will prevent the motor generator from operating as a generator in order to protect the energy storage from damage due to overcharging. In this mode, the motor generator may be used as a motor only to drive engine accessories and/or provide supplemental drive torque to the engine, or if there is no current engine accessory demand, allowed to rotate in a non-generating idle state.

The FEMG controller preferably communicates with several vehicle controllers, such as a vehicle's brake controller (which may control different types of brakes, such as pneumatic or hydraulic brakes), an engine and/or transmission controller, and one or more controllers that manage energy storage. These communications allow coordinated operation of the vehicle systems. For example, in the event that the braking demand is low enough that only the engine retarder need be used, the brake controller and the FEMG control module may signal each other to prioritize the motor-generator over the retarder's use so that the motor-generator provides regenerative braking if the energy state of charge will allow additional electrical energy to be stored (i.e., the energy storage state of charge is below the maximum allowed state of charge). Conversely, if the operating condition is not such that additional electrical power is required to be generated by the motor-generator, the FEMG control module may signal the brake controller to cause the brake controller to activate the retarder to provide the required amount of braking. Communication between the controllers is preferably ongoing, providing the ability to quickly update the status. For example, if the driver decreases the amount of braking demand during a braking event, the brake controller will be able to signal the FEMG control module to decrease the amount of regenerative braking.

Another example of possible inter-controller communication is coordination of air compressor operation with energy storage management. For example, the air compressor controller may signal the FEMG control module to operate the motor-generator with the clutch-pulley-damper disengaged (engine running or off) to drive the air compressor at a desired speed to supplement the compressed air storage caused by the large air consumption requirement (e.g., a tire inflation system attempting to counteract a large tire pressure leak, a large air leak in a tractor or trailer air line, use of the air landing gear of the trailer, a high air release during ABS system brake pressure regulation or activation of the trailer stability system on low friction roads, operation of the kingpin pneumatic lock/unlock device, or actuation of the pneumatic lift shaft).

Additional operational improvements provided by FEMG systems

In addition to the features, capabilities and advantages already mentioned, the front end motor-generator approach of the present invention has the important advantage of not requiring substantial modifications to the front of the vehicle, such as extending the front end of a commercial vehicle tractor or increasing the size of a diesel-powered municipal bus engine compartment. This is directly due to the fact that the FEMG system is easily housed between the front of the engine and the coolant radiator of the engine by using an integrated clutch-pulley damper unit and an associated axially narrow drive unit to transfer torque laterally to/from the motor generator. Accordingly, the FEMG system is well suited for incorporation into existing vehicle designs, both during new vehicle assembly and for upgrading old vehicles (particularly commercial vehicles) and stationary engine installations by retrofitting existing internal combustion engines using hybrid electric technology.

Another operational advantage provided by the FEMG system is its ability of the motor-generator to assist the engine in providing short duration "over-speed" vehicle operation. In such applications, the controller of the vehicle coordinates the increase in supplemental torque from the motor-generator and the temporary override of the vehicle speed regulator to allow a brief "flare" speed, for example, to allow a cut-in of a similar speed vehicle (e.g., another large truck) to be quickly accomplished. While use of such operating modes should be limited to brief, infrequent periods of time to minimize excessive loading of the engine and driveline components, the FEMG system may be programmed to provide a driver-actuated "overrun" mode, i.e., a driver-switchable option (e.g., "press-through" a button), to briefly increase speed as needed. Preferably, this push-through mode CAN be coordinated with the vehicle's blind spot monitoring controller via the CAN network, for example, to automatically terminate overspeed operation once the blind spot monitoring system indicates that the passing vehicle is no longer alongside. Such coordination would include the FEMG control module terminating the motor generator supplying supplemental torque to the engine crankshaft as part of the termination of the mode.

Motor-generator supplemental torque has further applications, such as reducing driver fatigue in driver assistance systems by automatically increasing torque, which may minimize the need for a driver to manually shift gears, particularly when climbing hills (and when meeting associated safety requirements, such as nothing in the field of view of the vehicle's adaptive cruise control camera and/or radar system).

The supplemental motor-generator torque may also be used in a trailer weight determination system, where a known amount of additional torque is added and the resulting measurement of vehicle acceleration is used for vehicle mass calculation during the application of the supplemental torque.

In the case where there is a safety problem, the increase of the supplementary driving torque from the motor generator should be restricted. For example, when a low friction signal is received from the trailer indicating that the trailer wheels encounter a low friction surface, the command to supplement torque delivery should be disabled.

The application of the FEMG system is not limited to the application in which the motor generator is the only generator. Synergy may be achieved by adding an FEMG front-end device in the engine and/or drive train that also includes a motor-generator unit located aft of the crankshaft side of the FEMG clutch, for example at the rear of the engine (e.g. a flywheel motor-generator), in a downstream drive train (e.g. a motor-generator incorporated into the transmission) or at the front end of the crankshaft, i.e. on the constantly engaged side of the FEMG clutch-pulley-damper unit.

The combination of the FEMG system and the "rear end" hybrid electric arrangement provides opportunities for overall vehicle operation improvement. For example, the presence of front end and back end systems may allow for a reduction in the size and weight of one or both motor-generators while still meeting vehicle requirements, as neither motor-generator need be sized to handle the power requirements of all vehicles, wherein it is no longer necessary to meet the power generation and power supply requirements of all vehicles with only one motor-generator. Furthermore, if one of the two motor generators is able to meet at least the necessary vehicle requirements when the other motor generator fails, operational flexibility may be increased by the presence of the two motor generators, allowing the vehicle to continue operating, possibly with reduced performance, until a time or place is reached at which maintenance may be performed.

Operation of the FEMG system and the rear end motor-generator may also be coordinated to split and/or share the load as needed to optimize vehicle operation. For example, where the FEMG system assumes engine accessory drive and energy storage charging requirements while the rear end motor-generator assists the engine by providing supplemental torque output to the vehicle driveline to help propel the vehicle, the load is split between the motor-generators. An example of shared synergy is the use of a rear end motor-generator to receive and store energy from regenerative braking of the driveline, while keeping the FEMG decoupled from the crankshaft to improve engine accessory efficiency (i.e., to allow capture of regenerative braking energy by the rear end motor-generator even when the FEMG system is decoupled from the crankshaft and therefore unable to capture otherwise wasted braking energy). The flexibility of combining the FEMG system with another portion of the hybrid system is unlimited, for example, operating both motor generators with an engaged FEMG clutch to cause both motor generators to provide supplemental drive torque or using both to capture regenerative braking energy for storage, etc.

The FEMG components and controller may also be suitable for applications that benefit from the ability to disengage engine accessories from the engine crankshaft, but do not require the power generation capabilities that a complete FEMG system installation would provide. Such "electric motor only" applications may include vehicles having operational needs that do not require the additional expense and complexity of high voltage electrical energy storage and distribution systems, but still can take advantage of the ability of the FEMG system to decouple the engine crankshaft from the accessory drive and use the FEMG motor to drive the accessories to improve efficiency. Such motor-only operation may be provided by a smaller, simpler battery pack whose state of charge may be maintained by the alternator of the vehicle engine.

For example, an engine in a container carrier used at a container ship port loading/unloading site would not require the ability to power for extended periods of time during engine outages, such as providing nighttime power to the sleeper compartments of an off-road truck. However, utilizing the crankshaft decoupling components of the FEMG system and their associated accessory drive control via the FEMG motor may improve container transport efficiency and/or torque output. For example, accessory loads may be removed from the engine by disengaging the crankshaft from the accessory drive under various operating conditions (e.g., during idle times); allowing the transporter system to be operated for a short period of time while the engine is stopped, thereby enabling fuel efficient engine start-stop operation; and efficiency improvements are achieved by removing the accessory drive torque requirement from the engine to put full engine torque output into the carrier drive when needed. Similarly, when it is desired to have the FEMG motor supplement the propulsion torque output of the engine, only the motor's FEMG system may be coupled to the engine crankshaft. This latter feature may be further improved by making the engine smaller in size, lighter in weight, and less costly to meet the "average" torque requirement, with the FEMG motor providing supplemental torque as needed to meet the designed total propulsion torque requirement of the vehicle.

In summary, the front end motor-generator system of the present invention is particularly well suited to provide new and retrofitted commercial, off-road and stationary engine installations having a hybrid electric powertrain with a mechanically simplified, space-efficient and cost-efficient universal electric drive that allows for variable speed control of engine accessories, the ability to drive the engine accessories independent of engine crankshaft speed, and the storage and return of energy to operate the electric powertrain for extended periods of engine non-operation, thereby improving significant overall fuel and cost efficiencies by:

minimizing engine accessory energy consumption, thereby improving fuel economy (i.e., removing accessory torque requirements on the internal combustion engine when the clutch-pulley-damper unit is disengaged from the engine crankshaft),

recovering otherwise wasted energy (e.g., generating electrical energy for storage rather than applying wheel brakes to convert vehicle kinetic energy into waste heat), and

extended component life (e.g., operating only accessories such as engine cooling fan, air conditioning compressor and air compressor as needed and at accessory speeds and/or duty cycles corresponding to actual vehicle requirements, rather than all accessories that are forced to operate at speeds dictated by engine crankshaft speed; minimizing brake wear and compressed air usage that would otherwise require engine-driven air compressor operation).

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.

Drawings

Fig. 1A and 1B are schematic diagrams of overall views of the arrangement of an FEMG system according to an embodiment of the present invention.

Fig. 2A-2C are cross-sectional views of an embodiment of a clutch-pulley-damper and assembled FEMG components according to the present invention.

Fig. 3A-3C are views of components of the clutch-pulley-damper unit of fig. 2A-2C.

Fig. 4 is a cross-sectional view of another embodiment of a clutch-pulley-damper unit according to the present invention.

Fig. 5 is a detailed cross-sectional view of a bearing arrangement at the end of a clutch-pulley-damper unit of a FEMG gearbox according to an embodiment of the present invention.

Fig. 6A-6C are oblique views of a FEMG drive unit in the form of a gearbox according to an embodiment of the invention.

Fig. 7 is a cross-sectional view of the FEMG gearbox of fig. 6A-6C.

Fig. 8 is an exploded view of a FEMG clutch pneumatic actuator diaphragm arrangement according to an embodiment of the invention.

Fig. 9 is an oblique view of another embodiment of a FEMG gearbox according to the present invention.

Fig. 10 is a schematic diagram of a FEMG gearbox mounting arrangement according to an embodiment of the invention.

Fig. 11 is a schematic diagram of a FEMG gearbox mounting arrangement according to an embodiment of the invention.

Fig. 12 is a schematic diagram of the relationship between the engine and the FEMG gearbox mounting bracket according to an embodiment of the invention.

Fig. 13 is a schematic diagram of the relationship between the engine, the FEMG gearbox and the FEMG gearbox mounting bracket according to an embodiment of the invention.

Fig. 14 is an oblique view of the FEMG gearbox mounting bracket as in fig. 12-13.

Fig. 15 is an oblique view of a motor generator according to an embodiment of the present invention.

FIG. 16 is a plot of power and torque produced by an exemplary motor-generator, according to an embodiment of the present invention.

Fig. 17 is an oblique perspective view of a cooling arrangement of a motor generator according to an embodiment of the present invention.

Fig. 18 is a block diagram of a FEMG system control and signal exchange arrangement according to an embodiment of the present invention.

Fig. 19 is a schematic diagram of AC and DC portions of a grid of a FEMG system according to an embodiment of the invention.

Fig. 20 is a schematic diagram of a power transistor arrangement for FEMG system control for AC and DC conversion according to an embodiment of the present invention.

Fig. 21 is a schematic diagram of a forward DC voltage converter arrangement controlled by the FEMG system according to an embodiment of the present invention.

Fig. 22 is a schematic diagram of a high voltage bi-directional DC/DC converter according to an embodiment of the present invention.

Fig. 23 is a graphical illustration of the voltage and current response across the bi-directional DC/DC converter of fig. 22.

Fig. 24 is an oblique view of a power electronics arrangement incorporated into a motor-generator according to an embodiment of the present invention.

Fig. 25 is a battery management system state of charge estimation control loop according to an embodiment of the present invention.

FIG. 26 is a flow chart of accessory operating speed selection according to an embodiment of the present invention.

FIG. 27 is a flowchart of a control strategy for operating the motor-generator and engine accessories independently of the engine, according to an embodiment of the present invention.

FIG. 28 is a flowchart of a control strategy for operating the motor-generator and engine accessories independently of the engine, according to an embodiment of the present invention.

Detailed Description

Front end motor generator system embodiments.

Fig. 1A is a schematic diagram showing components of an embodiment of a FEMG system according to the present invention. Fig. 1B is a schematic diagram of several FEMG system components in a commercial vehicle chassis. In this arrangement, the engine accessories (including the air compressor 1, the air conditioning compressor 2 and the engine cooling fan 7 arranged to draw cooling air through the engine coolant radiator 20) are belt driven from the pulley 5. The pulley 5 is positioned coaxially with a damper 6, the damper 6 being directly coupled to the crankshaft of an internal combustion engine 8. The accessories may be directly driven by the belt or provided with their own on/off or transmission clutches (not shown) which allow the separately clutched accessories to be partially or fully disengaged from the belt drive.

In addition to driving the accessory drive belt, the pulley 5 is also coupled to a drive unit having a reduction gear 4 to transmit torque between a crankshaft end of the drive unit and an opposite end coupled to the motor generator 3 (the drive unit housing is not shown in this figure for clarity). A disengageable coupling in the form of a clutch 15 is arranged between the crankshaft damper 6 and the pulley 5 (and thus the drive unit and the motor-generator 3). Although shown schematically as axially separated components in fig. 1A for clarity, in this embodiment the crankshaft 6, clutch 15 and pulley 5 at least partially overlap axially one another, thereby minimizing the axial depth of the combined pulley-clutch-damper unit ahead of the engine. Actuation of the pulley-clutch-damper clutch 15 between its engaged and disengaged states is controlled by an Electronic Control Unit (ECU) 13.

On the electrical side of the motor generator 3, the motor generator is electrically connected to a power inverter 14, the power inverter 14 converting Alternating Current (AC) produced by the motor generator output to Direct Current (DC) available in the energy storage and distribution system. Also in the reverse direction, the power inverter 14 converts direct current from the energy storage and distribution system to alternating current input to power the motor generator 3 as a torque producing motor. The inverter 14 is electrically connected to an energy storage unit 11 (hereinafter referred to as "energy storage") that can both receive energy for storage and output energy on demand.

In this embodiment, the energy storage 11 comprises lithium-based storage cells, each cell having a nominal charging voltage of about 3.7V (operating range of 2.1V to 4.1V), the lithium-based storage cells being connected in series to provide a nominal energy storage voltage of 400 volts (operating voltage range of about 300 volts to 400 volts), with a storage capacity of about 12 to 17 kilowatt-hours of electrical energy. Alternatively, the cells may be connected in series and parallel as desired to suit the application. For example, 28 modules with four series-connected cells per module may be connected in series and in parallel to provide the same 17 kilowatt-hour stored energy storage as the first example described above, but with a nominal operating voltage of 200V volts and twice the current output of the first example.

In addition to the relatively high capacity, low charge and discharge rate lithium based storage cells, the energy storage 11 in this embodiment also includes a plurality of relatively low capacity, high charge and discharge rate supercapacitors to provide the energy storage with a very large current that can be received and/or discharged within a short period of time that cannot be handled by lithium based storage cells (such cells are typically limited to charge/discharge rates of less than 1C to just a few C).

FEMG system hardware assembly embodiment.

Fig. 2A-2C show cross-sectional views of an embodiment of the clutch-pulley-damper unit 19 and an assembled configuration of the FEMG system hardware having the clutch-pulley-damper embodiment. In this embodiment, the gearbox 16 containing the reduction gear 4 receives the motor-generator 3 at the motor-generator end of the gearbox. The motor generator 3 is fixed to a housing of the gear box 16 by a fastener such as a bolt (not shown). The rotor shaft 18 of the motor-generator 3 engages the respective central bore of the adjacent coaxially positioned gear of the reduction gear 4 to allow torque to be transmitted between the motor-generator 3 and the reduction gear 4.

In this embodiment, at the crankshaft end of the gear case 16, the reduction gear 4 coaxially aligned with the clutch-pulley-damper unit 19 is coupled to the pulley side of the clutch-pulley-damper unit 19 by a bolt (not shown) passing through the coaxial reduction gear 4 for common rotation. The coupled engine-side portion (the portion having the crankshaft damper 6) is configured to be coupled to the front end of the engine crankshaft by a fastener or other suitable connection that ensures co-rotation of the engine-side portion 6 with the crankshaft. As described further below, the gear box 16 is separately mounted to a structure that maintains the clutch-pulley-damper unit 19 in coaxial alignment with the forward end of the engine crankshaft.

The cross-sectional view in fig. 2B is a view from above the FEMG front end hardware, while the oblique cross-sectional view in fig. 2C is a view at the crankshaft end of the gearbox 16. In this embodiment, the gear box, the motor generator, and the clutch-pulley-damper unit assembly are arranged such that the motor generator 3 is located on the left side of the engine crankshaft and on the front side of the gear box 16 (the side away from the front of the engine), wherein the motor generator 3 may be located in a space below or directly behind the vehicle engine coolant radiator 20. Alternatively, to accommodate different vehicle arrangements, the gearbox 16 may be mounted with the motor-generator 3 at the rear of the gearbox 16, preferably in the space transverse to the left side of the engine crankshaft (e.g., adjacent the oil pan at the bottom of the engine). The gearbox 16 may also be provided with a double-sided motor-generator mounting feature, such that a common gearbox design may be used for both vehicular applications with a front-facing motor-generator and vehicular applications with a motor-generator mounted to the rear side of the gearbox.

An FEMG clutch-pulley-damper unit embodiment.

Fig. 3A-3C are views of the components of the clutch-pulley-damper unit 19 of fig. 2A-2C. When assembled, the unit is extremely narrow in the axial direction due to the substantial axial overlap of the pulley 5, the engine-side portion 6 (hereinafter referred to as damper 6), and the clutch 15. In this embodiment, the pulley 5 has two belt transmission portions 21 configured to drive an accessory drive belt (not shown), e.g., one portion arranged to drive the engine cooling fan 7 around the clutch 15 and the other portion arranged to drive other engine accessories, e.g., the air compressor 1. In this example, the belt portion 21 concentrically surrounds the damper 6 and the clutch 15 (the belt portion 21 surrounding the damper 6 is omitted in fig. 2B and 2C for clarity).

Within the clutch-pulley-damper unit 19, the clutch 15 comprises two axially engaging dog clutch elements 25, 26. As shown in the cross-sectional views of fig. 2A-2C, in this embodiment, the central dog clutch element 25 is fixed for rotation with the damper 6 by a bolt extending from the FEMG gearbox side of the clutch-pulley-damper unit 19 through an axial bolt hole 28. Pulley 5 is rotatably supported on central core element 25 by bearings 34.

The engine-side portion of the outer periphery of the central core dog clutch element 25 comprises external splines 29, which external splines 29 are arranged to engage corresponding internal splines 30 at the inner periphery of the axially movable dog clutch element 26. The external splines 29 and the internal splines 30 are constantly engaged so that the movable dog clutch element 26 rotates with the damper 6 while being axially movable along the damper rotation axis.

The movable dog clutch element 26 is further provided with axially forward facing dogs 31, the dogs 31 being circumferentially distributed around the gearbox side (the side remote from the engine) of the element 26. As shown in fig. 3C, the pawls 31 are configured to engage spaces between respective pawls 32 on the engine-facing side of the pulley 5. The movable dog clutch element 26 is biased in the engaged position in the clutch-pulley-damper unit by a spring 33 located between the damper 6 and the movable dog clutch element 26, as shown in fig. 2A. Fig. 2B and 2C show the clutch disengaged position, in which the spring 33 is compressed when the moveable dog clutch element 26 is axially displaced towards the damper 6.

In this embodiment, the clutch ejection lever 27 is concentrically positioned within the central core dog clutch element 25. The engine-side end of the ejector rod 27 is arranged to exert an axial clutch-disengagement force which overcomes the bias of the spring 33 to axially displace the dog clutch element 26 towards the damper 6, so as to disengage its forward-facing dog 31 from the corresponding dog 32 of the pulley 5, which faces towards the engine side. In this embodiment, the gearbox end of the clutch ejection lever 27 is provided with a bushing 303 and a bearing 304, the bearing 304 enabling the bushing to remain stationary while the ejection lever 27 rotates.

The clutch ejection rod 27 is axially displaced to disengage and engage the dog clutch 15 by the clutch actuator 22. In this embodiment, the clutch actuator 22 is pneumatically actuated, wherein compressed air enters the attachment 305 through the clutch actuator diaphragm 41, causing a central portion of the diaphragm 41 to contact the throw rod bushing 303 to axially displace the clutch throw rod 27 toward the engine 5, thereby disengaging the clutch 15. When compressed air pressure is removed from the clutch actuator, the diaphragm 41 retracts from the engine, allowing the biasing spring 33 to axially displace the throw rod 27 and dog clutch element 26 towards the pulley 5 to re-engage the clutch pawls 31, 32 so that the pulley 5 rotates with the damper 6.

Fig. 4 shows an alternative embodiment of the clutch-pulley-damper unit 19, in which the clutch 15 is a so-called wet multiplate clutch. The wet multiplate clutch includes a friction driven plate 23 splined in an alternating manner to the inner periphery of the pulley 5 and the outer periphery of the center portion of the damper 6. The clutch plates 23 are compressed in the axial direction by a spring 24 between the damper 6 and the clutch actuator 22 (in this embodiment a pneumatically actuated clutch actuation piston). The bias by which the friction driven plates are stacked together by the spring 24 engages the clutch 15 and causes the pulley 5 and damper 6 to rotate in unison with one another about the axis of rotation of the engine crankshaft. When hydraulic pressure is applied to clutch actuator 22 (on the FEMG gearbox side of the actuator), springs 24 are compressed, allowing alternate clutch friction driven plates 23 to axially disengage, thereby placing clutch 15 in a disengaged state, i.e., a state in which pulley 5 and damper 6 rotate independently.

In this embodiment, the hydraulic pressure is supplied by oil which is also used to cool and lubricate the gearbox reduction gears and their associated bearings, and to cool the friction driven plates of the wet multiplate clutch. The application of the hydraulic pressure is controlled by a solenoid valve (not shown) in response to a command from the FEMG electronic control unit 13. The clutch 15 is sized to ensure that a significant amount of torque that can pass between the engine crankshaft and the motor-generator is accommodated by the clutch without slipping. For this reason, due to the axially overlapping arrangement of the clutch-pulley-damper unit 19, the cooling design of this unit should be configured to ensure adequate cooling of the clutch plates during all operations. Although in this embodiment cooling is provided by oil circulating in the gearbox, other forced or passive cooling arrangements may be provided as long as the desired clutch temperature remains below the operating temperature limit of the clutch.

A FEMG gearbox embodiment.

Fig. 5 is a cross-sectional detail view of the bearing arrangement at the crankshaft end of an embodiment of the FEMG gearbox 16. Fig. 6A-6C and 7 show oblique views of this gearbox embodiment, with a pair of gearbox clamshell housing plates 35 enclosing the reduction gear 4, including a pulley end gear 36, an idler gear 37 and a motor-generator end gear 38.

In this application, the gear has 2: 1, but any gear ratio that suits the available space for a particular engine application may be provided while providing the desired ratio of crankshaft speed to motor-generator speed. The gears 36-38 may be spur gears, helical gears, or have other gear teeth (e.g., double helical herringbone gear teeth) as desired to meet the needs of a particular FEMG system application. These requirements include gear noise limits required to meet government noise emissions or driver comfort limits that may be met with helical gears, mechanical strength limits (e.g., tooth stress limits), or axial thrust limits that may be met with double helical herringbone gear teeth that produce equal and opposite axial thrust components.

The gearbox housing rotatably supports each reduction gear 36-38 with a bearing 39. The pulley end gear 36 comprises a plurality of through holes 40 in a circumferential ring inside its gear teeth, which correspond to the holes on the front face of the pulley 5 of the clutch-pulley-damper. These holes receive fasteners configured to rotationally fix pulley-end reduction gear 36 to pulley 5 for common rotation when driven by the crankshaft and/or the motor-generator.

The pulley end reduction gear 36 has a central aperture in the center thereof through which a pneumatic dog clutch actuation diaphragm 41 passes, located on the front face of the gearbox housing. A pneumatic diaphragm 41 extends and retracts axially a piston (not shown) arranged to engage a cup 27 on the dog clutch element 26 to control engagement and disengagement of the clutch 15 of the clutch-pulley-damper unit 19. The diaphragm 41 is shown covered by the pneumatic clutch actuator 22 in fig. 5, while fig. 7-8 show a simpler, thinner diaphragm cover 42 with a compressed air connection on its face, which is particularly suitable for space-constrained FEMG applications. Regardless of the diaphragm cover design, the diaphragm 41 is acted upon by the compressed air in the chamber above the front face of the diaphragm that is generated when the clutch actuator 22 or cover plate 42 is mounted on the diaphragm bore on the front face of the gearbox housing. The admission and release of compressed air may be controlled by solenoid valves (not shown) in response to commands from the FEMG control module 13. Although the clutch actuation mechanism in this embodiment is a pneumatically actuated diaphragm, the invention is not limited to a particular clutch actuator. For example, an electromechanical actuator, such as an electric solenoid, configured to extend an actuator rod to disengage a clutch member may be used.

Figures 5 and 8 provide further details of the mounting of the pneumatic diaphragm actuator of this embodiment. In this embodiment, the engine side of the diaphragm mounting ring 45 is configured to both support the front bearing 39 associated with the pulley end reduction gear 36 and receive the diaphragm 41 on its front side. The bearing 39 may be retained and axially supported by any suitable means, such as a snap ring, or by a nut 46 as shown in fig. 5. Once the mounting ring is secured in the large aperture shown on the front face of the gearbox housing flap 35, the pulley end reduction gear 36 and its bearings 39 and diaphragm 41 are axially fixed relative to the housing of the gearbox 16.

At the motor-generator end of the gearbox 16, a shaft hole 43 aligned with the rotational axis of the motor-generator-end reduction gear 38 is provided in at least one of the case flaps 35, as shown in fig. 6A to 6C and fig. 7. Shaft bore 43 is sized to allow the rotor shaft of motor-generator 3 (not shown in this figure) to enter gearbox 16 and engage motor-generator end gear 38 for common rotation.

The FEMG gearbox may be cooled and lubricated by oil. If the engine and gearbox share the same oil source, the oil may be stored in a separate oil sump, or alternatively, in a remote location, such as an external container or oil reservoir of the engine. By the movement of the gears or by a pump distributing pressurized oil (for example an electric pump or a mechanical pump driven by the rotation of the reduction gear), the oil can circulate throughout the gearbox and, in addition to lubricating and cooling the gears, can also cool the clutch plates of the wet clutch. Furthermore, the gearbox may be provided with an energy storage which ensures that a reserve of pressurized oil can still be used to actuate, for example, the clutch of the clutch-pulley-damper unit when the pressure generated by the pump is not immediately available. In such embodiments, a solenoid valve controlled by the FEMG control module may be used to release pressurized oil to operate an actuator of the hydraulic clutch.

Fig. 9 illustrates an example of a commercially available gearbox showing an alternative motor-generator mounting arrangement in which a motor-generator mounting flange 44 provides for mounting the motor-generator to the gearbox with fasteners without requiring the fasteners to penetrate into the gearbox housing.

In the foregoing embodiment, the end reduction gears 36,38 are in constant meshed engagement via the idler gear 37. However, the present invention is not limited to this type of single reduction parallel shaft gearbox. Conversely, other torque power transmission arrangements are also possible, such as chain or belt drives, or drives having components such as a torque transmission shaft at an angle to the axis of rotation of the switchable coupling (e.g. worm gear drives having a drive shaft rotating on an axis perpendicular to the axis of rotation of the switchable coupling), provided that they are able to withstand the torque to be transmitted without being so large that the axial depth of the gearbox becomes unacceptably large. Such an alternative gearbox arrangement may also be used in embodiments where the motor-generator 3 is not aligned parallel to the axis of rotation of the switchable coupling, but is positioned on the gearbox 16 and aligned as required for installation in areas of limited space (e.g. the motor-generator is attached at the end of the gearbox with its axis of rotation aligned with the gearbox torque transfer shaft which is not parallel to the axis of rotation of the switchable coupling).

The invention is also not limited to a constant mesh arrangement of fixed reduction ratios, as other arrangements may be used, such as variable diameter pulleys (similar to those used in some vehicle constant velocity transmissions) or internally disengageable gears, as long as the axial depth of the gearbox does not interfere with the position of the FEMG system components in the region ahead of the engine.

In the preferred embodiment, the reduction ratio of the FEMG gearbox reduction gears 36-38 is 2: 1, which is a ratio selected to better match crankshaft speed to the effective operating speed range of the motor-generator 3.

FEMG system hardware installation embodiment.

As described above, the FEMG assembly is preferably positioned such that the motor generator 3 is located in an area of the engine compartment that is offset below and to the side of the vehicle chassis rails supporting the engine. Fig. 10 shows such an arrangement as viewed from the front to the rear of the vehicle. The figure shows the relationship between the motor generator 3 and the crankshaft 47 of the engine 8 (located axially behind the gear box 16), the oil pan 48, the longitudinal chassis rails 49 and the transverse engine mount 50 in this embodiment.

In the above-described FEMG arrangement, the crankshaft 47, the clutch-pulley-damper unit 19, and the engine-side reduction gear 36 are located on the same rotational axis. To ensure that this relationship is maintained, the FEMG gearbox should be positioned in front of the engine in a manner that ensures that there is no relative movement between the engine and the gearbox either transverse to the axis of rotation of the crankshaft or about the axis of the crankshaft.

While the FEMG gearbox may be mounted in a manner that does not directly connect the gearbox to the engine (e.g., by suspending the FEMG gearbox from brackets connected to chassis rails that hold the engine), preferably the gearbox is directly coupled to an adjacent frame member or engine block. Examples of corresponding arrangements of mounting brackets of the FEMG gearbox to the engine and mounting holes in the gearbox are shown in figures 10-14.

In fig. 10, the FEMG gearbox 16 is directly secured to the engine 8 by fasteners 306 against rotational or lateral movement relative to the engine 8. Fig. 11 shows another approach, where a torque arm 307 (also called a tie rod) is attached at one end to an anchor point 308 of the FEMG gearbox 16 and at the opposite end to the adjacent frame rail 49, providing non-rotational support of the gearbox 16.

Another alternative FEMG mounting method is shown in fig. 12. In this embodiment, the mounting bracket 51 is provided with bolt holes 52 arranged around the bracket to align with corresponding holes in the engine block 8 that receive fasteners to provide engine-centric fixed support for the FEMG gearbox. In this example, the flat bottom of the mounting bracket 51 is arranged to be positioned on top of a resilient engine bracket, as is commonly used in commercial vehicle engine installations. The engine-side portion of the mounting bracket 51 is the portion of the bracket that must extend under and/or around the clutch-pulley damper unit to reach the portion of the FEMG gearbox mounting bracket where the gearbox may be coupled, while ensuring that sufficient clearance is available within the bracket to allow the clutch-pulley damper unit to rotate therein.

Fig. 13 and 14 schematically illustrate the location of the FEMG gearbox 16 on such a bracket, and the corresponding distribution of fastener holes around the FEMG reduction gear 36 and the FEMG side of the mounting bracket 51. Fig. 13 and 14 each show the circumferential arrangement of the respective fastener holes 53 on the FEMG gearbox 16 and on the FEMG gearbox side of the FEMG mounting bracket 51. In fig. 14, the engine-side portion and the FEMG gear case-side portion of the mounting bracket 51 are joined in a space (not shown in the drawings for clarity) where the clutch-pulley-damper unit 19 is not rotated, by an arm 54 extending parallel to the engine crankshaft axis. The schematically illustrated arm 54 is intended to convey the mounting bracket placement concept, it being understood that the connection between the engine side and the FEMG gearbox side of the mounting bracket may be any configuration that joins the front and rear sides of the bracket in order to secure the FEMG gearbox against movement relative to the engine crankshaft. For example, the arm 54 may be a rod welded or bolted to the front and/or rear side of the bracket, or the arm may be part of an integrally cast component that extends around the clutch-pulley-damper unit 19. Preferably, the mounting bracket 51 is designed such that its FEMG gearbox side portion has a fastener hole pattern that facilitates rotating the FEMG gearbox relative to the bracket as needed ("clocking") to index the gearbox at various angles to accommodate the FEMG components to various engine configurations, such as in retrofitting the FEMG system to various existing vehicle or stationary engine applications.

An FEMG system motor generator and an electronic control embodiment.

An example of a motor generator suitable for attachment to the motor generator end of a FEMG gearbox is shown in fig. 15. In this embodiment, the FEMG gearbox side 55 of the motor generator 3 includes a plurality of studs 56, the studs 56 configured to engage corresponding holes in a mounting flange on the gearbox (e.g., the mounting flange 44 shown on the exemplary gearbox 16 in fig. 9). To transmit torque between the rotor of the motor-generator 3 and the reduction gear 38 on the motor-generator side, the rotor bore 57 receives a shaft (not shown) that extends into a corresponding bore in the reduction gear 38. The shaft between the reduction gear 38 and the rotor of the motor generator 3 may be a separate component, or may be integrally formed with the rotor or the reduction gear. The shaft may also be pressed into one or both of the rotor and the reduction gear, or may be easily separated by using a displaceable connection, such as an axial spline or a threaded connection.

The motor generator 3 in this embodiment also houses several electronic components of the FEMG system, discussed further below, as well as a low voltage connection 58 and a high voltage connection 59 that serve as electrical interfaces between the motor generator 3 and the control and energy storage components of the FEMG system.

Preferably, the motor generator 3 is sized to provide at least engine starting, hybrid power generation and engine accessory drive capability. In one embodiment, as shown in the graph of FIG. 16, a motor-generator sized with a diameter of approximately 220mm and a longitudinal depth of 180mm will provide approximately 300Nm of torque at zero rpm for engine starting, and up to approximately 100Nm near 4000rpm for operating engine accessories and/or providing supplemental torque to the engine crankshaft to assist in propelling the vehicle. 2: 1, the speed range of such a motor generator closely matches the speed range of zero to about 2000rpm of a typical commercial vehicle engine.

FEMG motor-generator design is limited by thermal, mechanical and electrical considerationsAnd (5) preparing. For example, while the temperature rise of the motor-generator during start-up is relatively limited by the relatively short duration of the start-up operation, the required torque output from the motor may be in the range of 50Nm to 100Nm when the motor-generator alone is driving one or more demanding engine accessories (e.g., an engine cooling fan). Without sufficient motor-generator cooling, the temperature rise during sustained high torque output conditions may be significant. For example, the current density J in the dynamo-electric machine winding is 15A/mm²The adiabatic temperature rise may be around 30 c. Accordingly, the FEMG motor generator is preferably provided with forced cooling, such as the example shown in fig. 17, in which engine coolant or cooling oil (e.g., oil from a gearbox oil circuit) is circulated through cooling fluid passages 60 in the motor generator. It is particularly preferable that a part 61 of the cooling passage 60 is also guided to provide cooling to the FEMG system electronic components mounted on the motor generator 3.

The type of motor selected may also introduce limitations or provide certain advantages. For example, in an induction motor, the use of an inverter (with a corresponding flux increase) can increase the breakdown torque by 10-20%, and the breakdown torque is typically high, e.g., 2-3 times the machine rating. On the other hand, if a permanent magnet type machine is chosen, excessive stator excitation current must be avoided to minimize the demagnetization potential of the permanent magnet. While physical placement and operating temperature can affect demagnetization issues, current values greater than twice the rated current must typically be experienced before significant demagnetization is noted.

In view of these factors, the preferred embodiment of the motor-generator 3 will have the ability to operate at 150% of its nominal operating range. For example, the motor-generator may have a rated speed of 4000rpm, have a maximum speed rating of 6000rpm (corresponding to a maximum engine speed of 3000 rpm), and have a capacity of approximately 60KW at 4000 rpm. Such a motor generator operating at a rated voltage of 400V is expected to provide a continuous torque output of about 100Nm, a short duration (e.g. 20 seconds) of 150Nm engine cranking torque, and a peak cranking torque of 300Nm at 0 rpm.

It should be noted that the term "motor generator" is not intended to limit the invention to applications in which the motor must also act as a generator, but includes applications in which the motor generator drives an accessory drive but is not dependent on the generation of electrical energy.

In this embodiment, the FEMG motor-generator 3 and other components of the FEMG system are controlled by a central FEMG control module 13, an electronic controller ("ECU"). Regarding the motor generator, the FEMG control module: (i) controlling operation modes of the motor generator including a torque output mode in which the motor generator outputs torque to be transmitted to the engine accessories and/or the engine crankshaft via the clutch-pulley-damper unit, a power generation mode in which the motor generator generates electrical energy for storage, an idle mode in which the motor generator does not generate torque or electrical energy, and a stop mode in which a speed of the motor generator is set to zero (a mode possible when there is no engine accessory operation requirement and the clutch of the clutch-pulley-damper unit is disengaged); and (ii) control the engagement state of the clutch-pulley-damper unit (via components such as solenoid valves and/or relays required by the type of clutch actuator used).

The FEMG control module 13 controls the motor-generator 3 and the clutch-pulley-damper unit 19 based on various sensor inputs and predetermined operating criteria, as discussed further below, such as the state of charge of the energy storage 11, the temperature level of the high voltage battery pack within the energy storage, and the current or anticipated torque demand on the motor-generator 3 (e.g., the torque required to achieve a desired engine accessory rotational speed to achieve a desired level of engine accessory operating efficiency). The FEMG control module 13 also monitors speed signals associated with the motor-generator and engine crankshafts to minimize the possibility of damaging clutch components by ensuring that the crankshaft-side and pulley-side portions of the clutch are speed matched before signaling the clutch actuator to engage the clutch.

The FEMG control module 13 uses digital and/or analog signals to communicate with other vehicle electronics modules to obtain data for use in its motor-generator and clutch-pulley-damper control algorithms, and to cooperate with other vehicle controllers to determine the best combination of overall system operation. In one embodiment, for example, the FEMG control module 13 is configured to receive a signal from a brake controller to operate the motor-generator in a generating mode to provide regenerative braking in lieu of applying mechanical brakes of the vehicle in response to a relatively low braking demand from the driver. The FEMG control module 13 is programmed to evaluate the current vehicle operating conditions and provide a signal to the brake controller indicating that regenerative braking is being initiated, or that electrical energy generation is not required and that the brake controller should command actuation of the mechanical brakes or retarders of the vehicle, upon receipt of such a signal.

Fig. 18 provides an example of incorporating electronic control in an FEMG system. In this embodiment, the FEMG control module 13 receives and outputs signals that are bi-directionally communicated with sensors, actuators, and other vehicle controllers via the CAN bus of the vehicle. In this example, the FEMG control module 13 communicates with the battery management system 12, the engine control unit 63, and the power management components of the FEMG system, the battery management system 12 monitoring the state of charge of the energy storage 11 and other relevant energy management parameters, the engine control unit 63 monitoring engine sensors and controlling the operation of the internal combustion engine, the power management components of the FEMG system including the power inverter 14, the power inverter 14 handling AC/DC conversion between the AC motor generator 3 and the DC portion of the electrical bus between the DC energy storage and the electrical consumer (not shown in this figure) of the vehicle. The FEMG control module 13 also communicates with a DC-DC converter 10 of the vehicle, which DC-DC converter 10 manages the distribution of electrical energy suitable for the voltage of the consumers, for example, 400V power is converted from the energy storage 11 to 12V required by the 12V battery 9 of the vehicle and various 12V devices of the vehicle (e.g. lighting, radio, power seats, etc.).

Fig. 18 also shows communication of data input to the FEMG system control algorithm from sensors 64 associated with the motor-generator 3, the clutch of the clutch-pulley-damper unit 19, the various engine accessories 1 and 12V battery 9 (e.g., motor-generator clutch position sensor 101, motor-generator speed sensor 102, engine accessory clutch position 103, air compressor state sensor 104, dynamic heater state sensor 105, FEMG coolant temperature sensor 106, FEMG coolant pressure sensor 107, and 12V battery voltage sensor 108).

Many of the signals received and exchanged by the FEMG control module 13 are transmitted to/from other vehicle devices 66 (e.g., brake controller 111, retarder controller 112, Electronic Air Control (EAC) controller 113, transmission controller 114 and dashboard controller 115) via the vehicle's SAE J1939 standard compliant communication and diagnostic bus 65. Examples of sensor and operational signal types and variables exchanged and their corresponding sources are provided in table 1.

TABLE 1

The outputs from the FEMG control module 13 include commands to control the electrical energy production or torque output from the motor-generator 3, commands to engage and disengage the clutches of the clutch-pulley-damper unit 19, commands to engage and disengage the clutches 120 (discussed further below) of the various engine accessories 1, and commands for operation of the FEMG coolant pump 121.

And the FEMG control module of the FEMG system component controls the system.

In addition to controlling the motor-generator and its clutching connection to the engine crankshaft, in this embodiment the FEMG control module is also able to control the engagement state of any or all of the individual clutches connecting the engine accessories to the accessory drive belt driven by pulley 5, thereby allowing the FEMG control module to selectively connect and disconnect different engine accessories (e.g., air conditioning compressor 2 or compressed air compressor 1 of the vehicle) from the accessory drive depending on the operating state of the vehicle. For example, the algorithm of the FEMG control module may prioritize electrical energy generation when operating conditions permit and determine that some engine accessories do not need to be operated. Alternatively, the FEMG control module is programmed to operate the engine accessories in response to a priority that requires operating the accessories, even if doing so does not result in high overall vehicle operating efficiency. An example of the latter is receiving a compressed air reservoir low pressure signal, requiring engagement of the air compressor clutch and operation of the pulley 5 at a sufficiently high speed to ensure that sufficient compressed air is stored to meet the safety requirements of the vehicle (e.g. sufficient compressed air for pneumatic braking operation). Another example is to command the motor-generator and engine cooling fan clutch to operate the engine cooling fan at a high enough speed to ensure adequate engine cooling to prevent engine damage.

Preferably, the FEMG control module is provided with engine accessory operating performance data, for example in the form of a stored look-up table. With the engine accessory operating efficiency information, the operating speed of the motor generator can be variably controlled to almost any desired speed when the clutch of the clutch-pulley-damper unit is disengaged, and knowing the operating state of the vehicle received from the sensors and the vehicle's communication network, the FEMG control module 13 is programmed to determine and command a combination of a preferred motor generator speed and an engine assist clutch engagement state that results in a high level of overall vehicle system efficiency for a given operating condition.

While overall system efficiency may be improved by the presence of a large number of individual engine accessory clutches (including on/off, multi-stage or variable slip clutches), even in the absence of individual accessory clutches, the FEMG control module 13 may use the engine accessory performance information to determine a preferred motor-generator operating speed at which to rotate the pulley 5 at a speed that meets current system priorities, whether that priority increases system efficiency, ensures that the heaviest engine accessory requirements are met, or to determine another priority, such as to begin charging the energy storage 11 sufficiently at a predetermined time prior to a predetermined event to ensure that sufficient electrical energy is stored before the vehicle stops. For example, the FEMG control module in this embodiment is programmed to determine the current state of charge of the energy storage 11 and the amount of time available prior to an expected driver rest period, and to initiate motor-generator charging of the energy storage 11 for an expected duration of a reset period (e.g., an 8 hour overnight rest period) at a rate that will result in sufficient energy being present at engine off to support vehicle system operation (e.g., sleeper compartment air conditioning).

A similar rationale applies regardless of how many individual engine accessory clutches are present, i.e., the FEMG control module may be programmed to operate the motor-generator 3 and the clutch 15 of the clutch-pulley-damper unit in a manner that satisfies the priorities established in the algorithm, regardless of whether there are several, multiple, or no individual engine accessory clutches. Similarly, various priority schemes may be programmed into the FEMG control module to suit particular vehicle applications. For example, in a preferred embodiment, the energy efficiency priority algorithm may go beyond a configuration that simply analyzes pulley speed, and the individual engine accessory clutch engagements provide the best operating efficiency for the highest priority engine accessories, and it may also be determined whether combined operation of the engine accessories at compromised pulley speeds will result in higher overall system efficiency while still meeting the requirements of the priority accessories, i.e., if there is a pulley speed that maximizes overall vehicle efficiency, then each individual engine accessory is operated at a speed that is offset from its respective maximum efficiency operating point while still meeting the vehicle system requirements.

FEMG power generation, storage, and voltage conversion embodiments.

The relationship between the power electronics and the current distribution in this embodiment is shown in more detail in fig. 19. The three phases of the ac motor generator 3 are connected to an AD/DC power inverter 14 via a high-voltage connection. The electric energy generated by the motor generator 3 is converted into a high voltage DC current for distribution over the DC bus network 67. Conversely, a DC current may be supplied to the bidirectional power inverter 14 to be converted into an AC current, thereby driving the motor generator 3 as a torque-generating motor.

Fig. 20 illustrates a known embodiment of a bi-directional AC/DC power inverter, such as inverter 14. The arrangement includes a six IGBT power transistor configuration in which switching signals are provided from a controller (e.g., from the FEMG control module 13) to the control lines 68A-68F based on a vector control strategy. Preferably, the control module for power inverter 14 is located no more than 15cm from the IGBT board of the power inverter. If it is desired to minimize electrical noise on the DC bus 67, a filter 69 may be interposed between the power inverter and the remainder of the DC bus.

Fig. 19 also shows the high voltage lines between the two main DC bus connections, i.e. the power inverter 14 and the energy storage 11. The double-headed arrows in the figure indicate that DC current may be transferred from the power inverter 14 to the energy storage 11 to increase its state of charge, or may flow from the energy storage to the DC bus 67 for distribution to the power inverter 14 to drive the motor-generator 3 or to other DC voltage consumers connected to the DC bus. In this embodiment, a DC/DC voltage converter 70 is provided between the DC bus and the energy storage 11 to adapt the DC voltage on the DC bus generated by the motor-generator 3 to the preferred operating voltage of the energy storage. Fig. 19 also shows that the DC bus 67 may also be connected to a suitable voltage converter (e.g., AC-DC voltage converter 309) that converts electrical energy from an offboard power supply 310, such as a stationary charging station, to a voltage on the DC bus 67 to allow charging of the energy storage independent of the motor-generator 3 when the vehicle is parked.

In addition to the bi-directional flow of DC current to and from the energy storage 11, the DC bus 67 also supplies high voltage DC current to vehicle electrical consumers (e.g., lights, radios and other devices that typically supply 12V), as well as to 120V AC current devices (e.g., driver sleeper compartment air conditioners and/or refrigerators or cooking surfaces). In both cases, a suitable voltage converter is provided to convert the high voltage on the DC bus 67 to a suitable DC or AC current at a suitable voltage. In the embodiment shown in fig. 19, the DC/DC converter 71 converts the DC current at nominal voltage to a DC current of about 400V to 12V to charge one or more conventional 12V batteries 72. Thus, the vehicle's typical 12V load 73 is provided with the required amount of 12V power as needed without having to equip the engine with a separate engine-driven 12V alternator, thereby further saving weight and cost while improving overall vehicle efficiency. Fig. 21 shows a known embodiment of a forward DC/DC converter, such as DC/DC converter 71, in which the FEMG control module 13 controls the conversion of the high DC voltage from the DC bus 67 to the 12V output 75 of the converter by providing a FEMG control signal to the transistor drive circuit 74 to manage the current through the primary winding 76 of the transformer 77 of the DC/DC converter.

The bidirectional high-voltage DC/DC converter 70 is a so-called "buck + boost" type voltage converter, such as the known electrical arrangement shown in fig. 22. FIG. 23 shows the input voltage V when the electronically controlled switch S of FIG. 22 is actuated_inThe respective current oscillations across inductor L and capacitor C are driven in a pulsed manner, thereby generating a voltage around a baseline<v_o>Smoothly oscillating continuous output voltage v_o。

By integrating several electronic components into the housing of the motor generator, it is possible to satisfy the desire to keep the distance between the power inverter 14 and the three AC phase lines of the motor generator short, as shown in fig. 24. On the side of the motor generator opposite to the side that will face the gear box 16, the three AC-phase lines 78A-78C appear and are connected to the high voltage portion 79 of the circuit board 84 (the portion of the circuit board 84 on the left side of the broken line in fig. 24). On the right side of the AC connection, the power inverter is integrated into a circuit board 84 with the IGBT components 80 located below the IGBT driver circuit 81.

Also co-located on the circuit board 84 is a portion 82 containing an electrical noise rejection electromagnetic interference (EMI) filter and DC power capacitors, and an embedded microcontroller 83 of the FEMG ECU. The dashed lines represent electrical isolation 85 of the high voltage portion 79 from the low voltage portion 86, which communicates with the rest of the FEMG system and vehicle components via electrical connector 58. The high voltage and high current generated by the motor-generator 3 or received by the motor-generator 3 from the energy storage 11 are transferred from the high voltage portion 79 of the circuit board 84 to the high voltage connector 59 via a circuit path (not shown) behind the outer surface of the circuit board.

The advantages of this high degree of motor-generator and power electronics integration are simplified and low cost installation, minimized electrical losses for long distance connections between the motor-generator and the power electronics, and the ability to provide cooling to the power electronics from the already existing forced cooling of the motor-generator without the need for additional dedicated electronic cooling arrangements.

FEMG system energy storage and battery management controller embodiments.

In this embodiment, the storage cells used in the energy storage 11 are based on lithium chemistry, in particular lithium ion batteries. Lithium ions have several advantages over conventional battery chemistries (e.g., lead-acid), including lighter weight, better charge rate tolerance for "fast charge", high power density, high energy storage and return efficiency, and longer cycle life.

In addition to requiring sufficient high voltage current to generate over 100nm of torque to drive the engine accessories when the clutch-pulley-damper unit is disengaged from the engine crankshaft, the energy storage 11 is sized to receive very large currents from the motor-generator 3 and supply very large currents to the motor-generator 3 because the crankshaft-driven motor-generator can produce kilowatts of electrical energy and the energy storage-powered motor-generator can require a peak high voltage current of 300 amps to start the diesel engine.

While the super capacitor is able to handle the peak current requirements of the FEMG system, the battery portion of the energy storage 11 is sized to provide a sustained current discharge rate and total energy output to meet the highest current requirements required. Based on experience with commercial vehicle operation, the battery portion of energy storage 11 in this embodiment is sized to ensure satisfactory operation at 58KW worth of 10 minutes per hour (corresponding to the power requirement for periodic operation of the engine cooling fan at its maximum speed only by the motor-generator, and concurrent air conditioning and air compressor use). Calculations show that, assuming an operating efficiency of 95% for the power inverter 14, a 58KW discharge of 10 minutes per hour will require 10KWh of energy to be extracted from the energy storage 11. At a system voltage of 400V, this discharge amount requires a storage capacity of the energy storage battery of about 15Ah (ampere-hour).

In addition to calculating the minimum battery capacity to meet the expected maximum vehicle demand, the design of the battery portion of the energy storage 11 takes into account baseline operating requirements. For example, there is an operational desire to incompletely discharge the energy storage cells to avoid encountering conditions where the energy storage cannot meet direct vehicle demands (e.g., the engine cannot be started when the motor-generator is operated as an engine starting device), and to avoid potential battery damage resulting from discharging well below the minimum recommended cell operating voltage of the battery cell manufacturer (typically no less than 1.5-2V/cell for 3.8V-4.2V lithium-based battery cells). Thus, the design of the energy storage of the present embodiment includes a requirement that the maximum discharge requires that the battery portion of the energy storage not be discharged to a capacity below 50%. This demand results in the energy storage 11 having a battery capacity of 30 Ah.

A design target of 30Ah and using lithium ion battery cells, each with an individual nominal voltage of 3.8V, discharge capacity of 33Ah at a discharge rate of 0.3C (such cells weigh 0.8Kg and have rectangular dimensions of 290mm x 216mm x 7.1mm), it was determined that the required energy storage capacity (30 Ah at 400V) could be provided by packaging 4 individual cells in series to produce 33Ah battery modules with a nominal voltage of 15.2V, and then connecting 28 of these battery modules in series to provide a battery pack with a 33Ah capacity rated at 15.2V/module x 28 module of 425V (actual operating voltage is typically 400V or below 400V). The battery pack has a weight of about 90Kg (without a housing) and a volume of about 50 liters, which is easily accommodated with the chassis rails of a commercial vehicle.

The energy storage 11 is equipped with a Battery Management System (BMS) 12. The BMS control module monitors the state of charge and temperature of the battery pack, handles battery maintenance tasks such as cell balancing (monitoring and adjusting the state of charge of individual cells or groups of cells), and transmits battery pack status information to the FEMG control module 13. The battery management system 12 may be co-located with the FEMG control module 13 or at another location remote from the battery pack in the energy storage 11; however, the installation of the battery management system 12 with the energy storage 11 allows for the deployment and replacement of the modular energy storage system.

Another design consideration of the energy storage 11 that receives and discharges large amounts of high voltage current is the need for cooling. In the present embodiment, among the FEMG components, the energy storage 11, the motor generator 3, the power inverter 14, the gear box 16, and the clutch 15 of the clutch-pulley-damper unit 19, which need to be cooled, the battery storage 11 needs to be cooled most to avoid damage due to an over-temperature condition. The preferred temperature operating range for lithium ion batteries is-20 ℃ to 55 ℃. These temperatures are in contrast to the operating temperature limits of about 150 ℃ for the motor-generator 3, about 125 ℃ for the power inverter 14, and about 130 ℃ for the gearbox 16 (clutch 15 if the clutch is an oil bath wet clutch). In this embodiment, significant savings in complexity and cost are achieved by having all of the main FEMG components cooled by circulating oil in the gearbox for lubrication and cooling. This is possible if the battery pack of the energy storage 11 receives cooling oil as the first component downstream of the air/oil radiator, which dissipates heat from the oil, i.e. before the cooled oil recirculates and absorbs heat from other FEMG components in the oil cooling circuit. This arrangement ensures that the battery pack receives a flow of cooling oil that allows the battery pack to remain at a temperature below 55 c before the oil encounters higher temperatures in the motor generator, power inverter and transmission.

An embodiment of an FEMG system energy storage charge state determination algorithm.

The state of charge of the energy storage cell may be determined in various ways. FIG. 25 is an example of a known battery management system state of charge estimation control algorithm that may be used with the present invention. In a first step S101, the battery management system 12 is initialized at start-up ("on"). Step S102 symbolizes an estimate of the state of charge of the battery cells of the BMS by the so-called "coulomb counting" method, where an estimated baseline charge level is established by sampling the cell and pack voltages (V, T) and temperature, and from this point onwards, the amount of current (I) drawn into and out of the battery pack is tracked.

However, while this method of tracking the state of charge has the advantage of providing very accurate current monitoring in real time using relatively inexpensive technology, it does not provide a reliable indication of the amount of charge loss from the battery cell due to the phenomenon of self-discharge of the battery cell as a result of unwanted chemical reactions. Since this phenomenon is strongly dependent on temperature and may result in a large charge loss not being detected in step S102, in this embodiment the battery management system also performs an additional state of charge estimation step S103, a so-called "round robin" method. In this state of charge estimation method, the open circuit voltage of the battery cell is measured and compared to stored voltage/state of charge values to provide an estimate of the battery charge level, which inherently accounts for previous self-discharge losses. Additionally, by comparing with previously stored information, the self-discharge rate may be estimated, and the state of health of the battery may be estimated from the self-discharge rate (i.e., a high self-discharge rate indicates that the state of health of the battery cell is degraded compared to a new battery cell).

The "round-robin" approach has the disadvantage that it cannot be easily used in real-time because the battery pack of the energy storage 11 is used to receive and discharge high voltage current as needed to support ongoing vehicle operation. As a result, the state of charge and state of health estimation based on the open circuit voltage in step S103 is performed only when the cells of the energy storage are in a state in which the battery pack does not receive current or is not discharged from the battery pack. If the step S103 estimation cannot be performed, the battery management system routine proceeds to step S104, and estimates the battery state of charge and state of health using the latest step S103 in subsequent calculations.

Based on the cell and pack voltages, temperatures, current inputs and outputs from step S102, and the correction factors of the last step S103 taking into account the self-discharge effect, in step S104 the battery management system calculates the appropriate charge and discharge limits available for operation of the energy store 11 within the FEMG system, and executes a cell balancing algorithm to identify the battery cells requiring charge equalization and applies the appropriate selective cell charging and/or discharging to equalize the cell voltages within the 4 cell module and between the 28 modules. Cell balancing is particularly important when using lithium ion battery cells, since such cells can age and self-discharge at different rates from each other. As a result, over time, the individual battery cells may develop different capabilities to accept charging, which may result in one or more cells in a module (or between different modules) being overcharged while others are undercharged. In either case, a significantly overcharged or undercharged cell may be irreparably damaged.

In step S105, the battery management system 12 transmits battery pack state information including information on the required power limit for the current state of charge and the temperature of the battery cell to the FEMG control module 13. In step S106, the battery cell data is stored in memory in parallel for future cell monitoring iterations. After the battery state determination and cell balancing routines are completed, control returns to the beginning of the charge estimation control loop, making self-discharge rate data available at the beginning of the cycle for subsequent steps.

FEMG system operating modes and control algorithm embodiments.

In this embodiment, the FEMG system operates in several modes, including a generator mode, a motor mode, an idle mode, an off mode, and a stop/start mode. The mode selected for the current operating conditions is based at least in part on the current state of charge of the energy storage 11, with the FEMG control module 13 programmed to identify a minimum charge level, in this embodiment, 20% charge capacity, 40% intermediate charge level and 80% maximum charge level (the levels being selected to ensure that the energy storage is free from overcharging of the cells, particularly in the event that individual cell self-discharge has produced a cell imbalance condition) based on data received from the battery management system 12.

In the generator mode, whenever the state of charge of the energy store is below a minimum charge level, the clutch 15 is engaged and the motor-generator 3 is driven to produce electrical energy for storage, and the clutch will remain engaged until an intermediate state of charge level is reached. Once the intermediate state of charge level is reached, the FEMG control module 13 switches between generator, motor, idle and off modes as needed. For example, if motor-generator 3 is operated to drive the engine accessories with clutch 15 disengaged, the FEMG control module commands a switch to generator mode and engages clutch 15 to charge energy storage 11 when a braking, deceleration or negative torque event occurs (as long as the state of charge of energy storage 11 remains below a maximum state of charge level).

When in the motor mode with the clutch 15 disengaged, the FEMG control module 13 adjusts the amplitude and frequency of the current delivered by the inverter 14 to the motor generator 3 to provide continuously variable control. This capability allows the motor generator 3 to operate in a manner that drives the pulley 5, and thus drive the engine accessories from the pulley 5 at a speed and torque output level that meets the requirements of the current operating conditions, without wasting energy generated by operating at unnecessarily high speeds and torque output levels. The FEMG system has the added benefit of variable output control of the motor-generator 3 even though the amount of stored electrical energy that must be transferred from the energy storage 11 is minimised, reducing the energy storage charging requirements, and extending the length of time that the energy storage 11 can supply high voltage current before reaching a minimum state of charge.

If the charge level in the energy storage 11 is above the minimum level, there is no braking, retarding or negative torque condition, and the engine accessories are not requesting torque from the motor-generator 3, the FEMG control module 13 initiates an idle mode in which the clutch 15 of the clutch-pulley-damper 19 is disengaged and the motor-generator is "off," i.e., not operating to produce electrical energy for storage or to produce torque for driving the engine accessories.

In any of the generator, motor or off modes, if the engine requires torque output assist from the motor-generator, the FEMG control module may command the clutch 15 to engage and, at the same time, command the supply of electrical energy from the energy storage 11 to the motor-generator to convert to supplemental torque to be transmitted to the engine crankshaft.

The FEMG control module is additionally programmed to prevent accidental over-discharge of the energy storage 11. For example, in this embodiment, when the torque and speed requirements of the engine cooling fan 7 are above 90% of its design maximum requirements, the clutch 15 of the clutch-pulley-damper 19 is engaged to mechanically drive the engine cooling fan 7 (and thus, other engaged engine accessories) from the engine crankshaft. This allows the motor-generator 3 to operate in an idle or generator mode to avoid potentially damaging deep discharge of the energy storage 11, as well as avoid a state-of-charge condition in which the stored energy is insufficient to support an engine-off load (e.g., engine start-up or sleeper support during an engine-off rest).

The additional operating mode is a start mode for initially starting the cold engine and start-stop functions (i.e., shutting off the engine after a stop and restarting when driving is resumed). In this embodiment, the start-stop function is controlled by the FEMG control module 13. When appropriate conditions exist (e.g., energy storage 11 state of charge is above a minimum threshold for engine start, vehicle speed is zero for a sufficient period of time, transmission is in neutral or transmission clutch disengaged, doors are closed, etc.), the FEMG control module signals the engine control module to shut down the engine to minimize fuel consumption and undesirable engine idle noise. When the vehicle is to resume motion, as indicated by a signal such as release of the brake pedal or operation of the transmission clutch, the FEMG control module 13 commands engagement of the clutch 15 and energy supply from the energy storage 11 to operate the motor-generator 3 to generate a large amount of torque for engine start. Delivery of engine cranking torque occurs with zero motor generator initial speed, with or without engine accessory operation demand during engine shutdown (in which case pulley-crankshaft speed matching is not required, since zero speed is on both sides of the clutch). Alternatively, if the motor-generator 3 has driven the pulley 5 to power the engine accessories during engine shut-down, the motor-generator 3 will be commanded to slow down below the speed at which clutch damage will occur when the clutch 15 is engaged. In the case of a dog clutch, this may be zero speed or near zero speed, while a wet multiplate clutch may better tolerate some relative motion between the pulley side and the fixed crankshaft side of the clutch.

The FEMG system may also store sufficient energy to allow the dynamic heater to warm up operation of the cold engine prior to cold start, thereby significantly reducing the drag the cold engine will present to the motor generator during cold start. The use of a dynamic heat generator also creates opportunities for reducing the size, weight, and cost of the motor-generator by reducing the peak cold-start torque requirements that the motor-generator must be designed to provide under the expected operating conditions of the vehicle.

The peak cold start torque requirements that the motor generator must be designed to provide under the expected operating conditions of the vehicle may also be reduced by other auxiliary devices. For example, if the engine starting torque is supplemented by a pneumatic starter motor driven by the compressed air storage of the vehicle, the size of the motor generator may be reduced. The size of the pneumatic starter motor can be minimized to ensure that it can be positioned with the FEMG components at the front of the engine, since the size of the pneumatic starter motor need not be capable of starting the engine itself. Such a cold start assist device is less costly and lighter weight than the option of maintaining a conventional electric engine starter motor to rotate the engine flywheel, and has a negligible impact on the system energy efficiency improvement obtainable with a FEMG system.

An engine accessory operating speed and a motor generator operating speed determination algorithm of the FEMG system.

After a brief discussion of the basis of this strategy, an embodiment of the FEMG system control strategy is explained by means of the flowcharts of fig. 26 and 27.

In general, higher fuel savings may be achieved by maximizing the amount of time that engine accessories and other components are electrically driven, rather than by the mechanical power of the engine that is conventionally provided. Control strategies that improve power deployment are an important part of achieving these improvements. One approach of the present invention is to maximize the number of components that can be electrically driven while minimizing the number of motors required to drive the accessories. Thus, in the present invention, a single electric motor (e.g., motor-generator 3) provides both mechanical torque output and electrical energy generation, rather than providing most or all of the power requiring components of the vehicle with their own electric motor. The single motor generator approach is combined with a control strategy that ensures that the demands of the engine accessories or other components that require the highest or highest priority are met, while minimizing inefficient operation thereof by adapting the operation of the other accessories or components as much as possible to the conditions set to meet the maximum demands. In the control strategy discussed below, each engine accessory is provided with a clutch that can be selectively closed, driven at the speed indicated by the accessory having the greatest demand or priority, or driven at a reduced speed using a variable-engagement clutch, depending on the accessory.

When the engine accessories are driven by the engine crankshaft, i.e., when the clutch 15 is engaged, each engine accessory is mechanically driven under a "baseline" or "raw" control strategy (OCS), which corresponds to how these accessories will be operated in conventional engine applications without a FEMG system. In this strategy, accessories having separate clutches are operated according to their respective baseline control schemes, with their clutches fully engaged, partially engaged, or disengaged in the same manner as in non-hybrid internal combustion engine applications.

Conversely, when the clutch 15 of the clutch-pulley-damper unit is disengaged and the engine accessories begin to be driven by the motor-generator 3 using energy from the energy storage 11, the FEMG control module variably controls the speed of the pulley 5, and thus the engine accessory drive belt, in a manner that meets current vehicle demands, without providing more accessory drive torque than is required by current operating conditions. Under such a gear change control (VSC) strategy, the FEMG control module 13 uses stored data regarding the operating characteristics of the various engine accessories to simultaneously control the various accessories in a manner that further minimizes the amount of electrical energy required to drive the motor generator 3 in the motoring mode (the FEMG control module 13 may directly control the accessories, or signal other modules such as the engine control module to command the required accessory operations to be performed). Further, while the most efficient or optimal operating speed has been plotted for each accessory, because the motor generator 3 drives all engine accessories on the same belt at one belt speed, when one accessory is operating at its optimum, the other accessories may be operating at a sub-optimal operating point. For this reason, the FEMG control module 13 compares the preferred operating speed of each accessory to the speed at which they are driven by the motor-generator 3 at a speed sufficient to meet the maximum accessory demand, and determines whether the respective clutches of the accessories can be actuated to produce an individual accessory speed that is closer to the preferred operating speed of the individual accessories. The FEMG control module will override the usual accessory clutch control strategy if possible and activate the accessory clutch as needed to deliver a single accessory speed that provides improved efficiency.

Selection of the appropriate engine accessory speed begins with the determination of the desired operating speed for each accessory under the current operating conditions using control logic such as that shown in FIG. 26.

Upon activation of the accessory speed determination algorithm, the FEMG control module 13 retrieves data from its memory 201 regarding the current vehicle operating conditions obtained from the sensors and other controllers of the vehicle, most of which are provided to the FEMG control module 13 via the CAN bus in accordance with the SAE J1939 network protocol, from its memory 201, and determines the current operating conditions in step S201. This operation is a prediction (predict) to determine whether the current operating conditions require operation of a specific accessory (e.g., an engine cooling fan) in step S202. If the accessories are to be turned on, the program proceeds to step S203 to determine whether the accessories are coupled to the accessory drive via a separate accessory multi-speed clutch.

If at step S203 the FEMG control module 13 determines that such an accessory clutch is present, the process proceeds to step S204 to determine what desired accessory operating speed will be for the determined operating conditions. In performing step S204, the FEMG control module 13 accesses the information 202, for example in the form of a look-up table, a characteristic curve or a mathematical function, from which the operating speed of the accessory at which the accessory is effectively operating under the current operating conditions can be determined. At step S205, the FEMG control module 13 compares the determined desired accessory operating speed with the speed of the accessories when its clutch is fully engaged, and adjusts the accessory clutch to set the appropriate corresponding clutch operating state (e.g., degree of clutch slip in a variable slip clutch or a particular reduction ratio in a clutch with discrete multiple speeds (e.g., a 3-speed clutch)). After appropriately adjusting the accessory clutch according to the conditions, the FEMG control module 13 checks in step S207 whether the FEMG system motor mode has ended (i.e., determines whether the motor generator 3 has stopped driving the accessory drive via the pulley 5). If the system is still operating in the motor mode, control returns to the beginning of the accessory speed determination process to continue evaluating accessory speed requirements based on ongoing operating conditions. If it is determined in step S207 that the motor mode has ended, the routine of FIG. 26 ends. It should be noted that fig. 26 represents an accessory control algorithm when the FEMG system is not operating in a mode in which the motor generator drives the accessories ("motor mode"), that is, when the FEMG system is operating in a generator mode (engine drives the motor generator and the accessories), an off mode, or the FEMG system is disabled. If operated with an engine driven accessory (i.e., with the clutch of the switchable coupling engaged), control of the accessory and its respective clutch may be performed by, for example, a controller of the engine.

If, at step S203, the FEMG control module 13 determines that a multi-speed accessory clutch is not present (i.e., the accessory speed cannot be adjusted relative to the engine speed), then the routine proceeds directly to step S206 to command the clutch of the accessory to fully couple the accessory to the accessory drive. Control then transfers to step S207, where the motor mode evaluation described above is performed. It should be noted that fig. 26 represents an accessory control algorithm when the FEMG system is not operating in a mode in which the motor generator drives the accessories ("motor mode"), that is, when the FEMG system is operating in a generator mode (engine drives the motor generator and the accessories), an off mode, or the FEMG system is disabled. If operated with an engine driven accessory (i.e., with the clutch of the switchable coupling engaged), control of the accessory and its respective clutch may be performed by, for example, a controller of the engine.

The algorithm of FIG. 26 is a component of the overall engine accessory control strategy of the present embodiment shown in FIG. 27. At the start of the FEMG system algorithm, the FEMG control module 13 retrieves data received from the battery management system 12 from its memory 201 to determine the state of charge of the energy storage 11 in step S301. Next, in step S302, the FEMG control module 13 retrieves data from the memory 201 regarding the current vehicle operating conditions obtained from the sensors and other controllers of the vehicle to determine the current operating conditions under which the engine is operating (in this embodiment, the evaluation in step S302 provides the information required in step S201 of the accessory speed determination algorithm of fig. 26, and therefore need not be repeated in the following step S322).

After determining the current operating conditions, the FEMG control module 13 determines the mode in which the FEMG system should operate and commands engagement or disengagement of the clutch 15 of the clutch-pulley-damper unit 19 accordingly (step S303). If the clutch 15 is in an engaged state, with the pulley 5 coupled to the damper 6 (and thus to the engine crankshaft), the determination of how to operate the accessories using the engine pulley 5 may be performed by the FEMG control module 13 or other accessory control module. In fig. 27, at step S311, the FEMG control module 13 transfers control of the engine accessory clutch to the Engine Control Module (ECM) of the vehicle, which may determine the engine accessory speed in a manner comparable to the Original Control Strategy (OCS). After the accessory control is switched in step S311, the process ends in step S312.

If it is determined at step S303 that the motor-generator 3 is to electrically drive the accessory (i.e., a "motor mode" in which the clutch 15 of the clutch-pulley-damper unit 19 is in a disengaged state in which the pulley 5 is decoupled from the damper 6 and thus decoupled from the crankshaft), in this embodiment, a gear change control (VSC) strategy is used to control the motor-generator 3.

The VSC policy is here implemented by first determining a preferred accessory operating speed for each accessory in step S322, while taking into account the information on all accessory characteristics and variables evaluated in step S321.

In step S323, the FEMG control module 13 determines whether at least one accessory drivable by the motor generator 3 is in an "on" state, i.e., in a state to be driven by the motor generator 3 via the pulley 5. If there is no accessory operation request under the current conditions, control returns to step S303.

If it is determined in step S323 that there is at least one accessory in the "on" state, the FEMG control algorithm determines in step S324 whether more than one accessory needs to be driven by the motor generator 3 (i.e., more than one accessory is "on"). If there is only a single accessory having a torque request, the control process continues with a subroutine that focuses only on operation of that "on" accessory. Thus, at step S325, the motor generator speed required to drive the individual accessories at their preferred operating speed is calculated, the individual drive clutches of the accessories are commanded to be fully engaged at step S326, and the motor generator 3 is commanded to operate at the speed determined at step S325 at step S327. Since the speed of the motor generator is variably controlled in this embodiment, the pulley speed 5 can be accurately set to a level required to drive the highest-demand engine accessories. Control is then returned to the beginning of the control algorithm.

If it is determined at step S324 that more than one accessory needs to be driven by motor generator 3, the FEMG control module 13 determines, for each accessory, the motor generator speed required to drive the accessory at its respective preferred accessory operating speed, in accordance with the VSC strategy in step S328. The calculated speeds are then compared in step S329 to identify the highest motor-generator speed request from the "on" accessories. Then, the FEMG control module 13 commands the full engagement of the individual clutch of the accessory requiring the highest motor generator speed in step S330, and commands the motor generator 3 to operate at the required highest motor generator speed in step S331. As part of the VSC strategy, the FEMG control module controls operation of each of the remaining "on" accessories equipped with individual clutches in step S332 to adapt operation of those accessories to the desired maximum motor generator speed set in step S329. For example, because the set motor-generator speed (the speed required to service the accessory requiring the highest motor-generator speed) is higher than the speed required for the remaining accessories to operate at their preferred speed, if the accessories are equipped with a separate clutch that can be partially engaged (e.g., "slipped"), the clutch can be commanded to allow sufficient slip to bring the speed of its accessories closer to their preferred operating speed (as determined in step S322). Control is then returned to the beginning of the control algorithm.

An example of the execution of the foregoing method for the case of a vehicle having three accessories driven from a crankshaft pulley, an engine cooling fan, an air conditioning compressor, and an air compressor is provided below.

In this example, the engine cooling fan is equipped with a multi-speed capable fan clutch, such as a three-speed or a variable speed clutch (e.g., a viscous fan clutch). Air conditioners and air compressors have a single "on/off" clutch, which has only engaged and disengaged states. The FEMG control module 13 controls the operating state of each accessory clutch. The final speed of each accessory is a function of the pulley ratio, the motor-generator speed, and the nature of the accessory clutch (i.e., "on/off," variable slip, or multiple reduction ratio steps).

In this simplified example, for a given set of vehicle operating conditions, the preferred operating point for each accessory and the corresponding motor-generator speed at which the preferred operating point is obtained are: the engine cooling fan was run at 1050rpm (motor-generator speed of 1050 rpm/1.1 ratio between fan pulley and pulley 5, multiplied by a 2: 1 gearbox speed reduction ratio 1909rpm fan speed was required); the air-conditioning compressor was operated at 1100rpm (equivalent to 1294rpm for the motor generator); and the air compressor was operated at 2000rpm (corresponding to a motor generator speed of 2667 rpm).

If the FEMG control module 13 determines that the operation of the air compressor is the highest priority under given conditions (e.g. when the amount of stored compressed air is close to the minimum safe level for pneumatic brake operation), the FEMG control module 13 will command the motor-generator 3 to operate at 2667rpm required to support the 2000rpm speed demand of the air compressor. However, the motor generator speed is significantly higher than the speed required for the engine cooling fan or the air conditioning compressor (at a motor generator speed of 2667rpm, the engine cooling fan speed and the air conditioning compressor speed would be 1467rpm and 2267rpm, respectively). The engine accessory operating curve may be accessed and depending on the nature of the clutch of the other accessories, the FEMG control module 13 may then adjust the engagement of the clutch to operate the other accessories closer to their preferred operating speeds. For example, if the fan is equipped with a variable slip clutch, the FEMG control module may command an amount of fan clutch slip to provide a preferred engine cooling fan speed of 1100 rpm. Similarly, while the air conditioner compressor may only have an "on/off clutch and therefore will be driven at 1467rpm when its clutch is engaged (rather than the preferred speed of 1050 rpm), the FEMG control module may control operation of the" on/off clutch of the air conditioner compressor to reduce the duty cycle of the air conditioner compressor to a point where current air conditioning requirements can be met by periodically operating the air conditioner at only 1467 rpm. The method enables the FEMG control module to meet the needs of the currently most demanding engine accessories while reducing energy waste by driving other accessories at higher speeds than needed or at unnecessarily high duty cycles (e.g., 100%).

In another example, the engine may be equipped with an accessory that cannot be disconnected from the drive belt driven by pulley 5. In this case, the FEMG control module 13 may determine that the maximum overall system energy efficiency may be obtained by the trade-off when considering the operation curve. For example, suppose that the air compressor currently exhibits the greatest demand, and it is preferred to operate the air compressor at the 2000rpm speed at which the compressor is most efficient. If the FEMG control module then determines that the engine coolant pump driven at a motor-generator speed of 2667rpm will operate at an undesirably low efficiency (i.e., at a pump speed that significantly increases the energy consumption of the pump), and that vehicle conditions allow the air compressor to operate at a lower speed (e.g., currently required to "top up" the compressed air storage tank rather than meet an urgent safety-related compressed air requirement), the FEMG control module may command the engine coolant pump to operate at a lower motor-generator speed (e.g., 2400rpm) at a higher level of efficiency, even though the air compressor is operating at this speed at a slightly reduced efficiency, with the result that overall combined engine coolant pump and air compressor operation improves overall system efficiency as compared to operating these accessories at a motor-generator speed of 2667 rpm.

A further attachment operating strategy is shown in fig. 28. In this method, using the motor-generator (motor mode) driving the accessories as determined in step 303 of FIG. 27, the system first determines the minimum speed required for each accessory to meet current vehicle requirements (including zero speed for accessories that do not currently require "opening") in step S601. These become the "attachment required speed" for each attachment. Then, if the accessories are driven by the motor generator, the system determines motor generator speeds corresponding to the speeds required for the respective accessories (step S602).

The system then determines in step S603 which accessories are required for operational safety, i.e. which accessory operations are deemed to be "safety critical" to the operation of the vehicle. In step S604, it is determined whether the accessory with the highest speed requirement is a safety critical accessory. If this is the case, the highest attachment speed is selected as the basis for further operational calculations in step S605. The operating speeds of the remaining accessories (taking into account the gear ratios of the remaining accessories) that will be achieved when the accessory drive is operating at the highest accessory speed are determined in step S606. Then, as in steps S406-S407, at steps S607-S608, the system determines whether one or more of the remaining accessories can operate at a lower speed while continuing to meet their individual requirements (step S607), and in step S608, the system adjusts the clutch of the respective individual accessory to reduce its speed to a speed that only meets the individual requirements.

On the other hand, if the system determines at step S604 that the accessory with the highest speed requirement is not a safety critical accessory, then control passes to step S609.

At step S609, the system determines a second operational priority based on a plurality of operational need criteria, such as meeting vehicle requirements, energy storage requirements, need or desire to operate a single accessory at a desired performance level, need or desire to operate all "on" accessories at an operating point that can provide the best overall combined accessory efficiency, maintain driver comfort, etc., after the first safety priority. Based on the determination of the second operational priority, the system determines a motor generator speed that will satisfy the second operational priority (i.e., operating the accessories for satisfying the second operational priority at a sufficient speed to satisfy the second operational priority) at step S610. Similar to step S607, this motor-generator speed will be the current motor-generator operating speed, and will become the basis for determining the respective remaining accessory speeds in step S611 (taking into account the gear ratios of the various accessories). In steps S612-S613, as at steps S607-S608, the system determines whether one or more of the remaining accessories can operate at a lower speed while continuing to meet their individual requirements (step S607), and in step S608, the system modulates the clutch of the respective individual accessory to reduce its speed to a speed that only meets the individual requirements.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since such modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and their equivalents.

List of reference markers:

1 air compressor

2 air-conditioning compressor

3 Motor generator

4 drive unit gear

5 belt wheel

6 damper

7 Engine cooling fan

8 engine

9 vehicle battery

10 DC/DC converter

11 energy store

12 Battery management system

13 FEMG electronic control unit

14 AC/DC power inverter

15 Clutch

16 gear box

17 flanged shaft

18 rotor shaft

19 clutch-pulley-damper unit

20 engine coolant radiator

21 belt drive section

22 Clutch actuator

23 Clutch plate

24 clutch spring

25,26 dog clutch element

27 Clutch throw-out lever

28 bolt hole

29 external spline

30 internal spline

31, 32 claws

33 spring

34 bearing

35 gearbox shell flip

36 belt wheel end reduction gear

37 intermediate reduction gear

38 electric generator end reduction gear

39 bearing

40 holes

41 diaphragm

42 cover

43 axle hole

44 mounting flange

45 mounting ring

46 nut

47 crankshaft

48 oil pan

49 Chassis rails

50 Engine mount

51 mounting bracket

52 holes

53 holes

54 support arm

55 motor generator gearbox side

56 mounting stud

57 rotor shaft hole

58 low voltage connection

59 high-voltage connection

60 coolant channels

61 electron cooling channel section

62 Engine control Unit

64 sensor

65 SAE J1939 bus

66 vehicle equipment

67 DC bus

68A-68F control line

69 transistor control line

70 DC/DC voltage converter

71 DC/DC converter

7212V battery

7312V load

74 DC/DC converter transistor drive circuit

75 DC/DC converter output

76 transformer primary winding

77 Transformer

78 AC phase connection

79 circuit board

80 IGBT package

81 IGBT driver circuit

82 EMI filter and DC capacitor

83 FEMG control module microcontroller

101 motor generator clutch position sensor

102 motor generator speed sensor

103 engine accessory clutch position

104 air compressor state sensor

105 dynamic heater state sensor

106 FEMG coolant temperature sensor

107 FEMG coolant pressure sensor

10812V battery voltage sensor

111 brake controller

112 delayer controller

113 EAC controller

114 transmission controller

115 dashboard controller

120 individual engine accessory clutch

121 FEMG coolant pump

201 FEMG control module memory

202 FEMG control module operating parameter memory

303 clutch throwing-out rod bushing

304 bush bearing

305 compressed air accessory

306 fastener

307 torque arm

308 anchor point

309 AC-DC converter

310 external power supply

Claims (16)

1. A method of operating a motor-generator accessory drive system of a vehicle, the motor-generator accessory drive system having

A motor-generator for generating a motor-generator,

a torque transfer section having a motor-generator end configured to receive the motor-generator and transfer torque between the motor-generator end and an accessory drive end of the torque transfer section,

an accessory drive coupled to the accessory drive end of the torque transmission section and arranged to be driven by the motor generator via the torque transmission and to drive a plurality of accessories,

an energy storage configured to transfer stored electric energy to the motor-generator to generate torque output from the motor-generator to the torque transfer section, an

A motor generator system controller configured to control at least one of an operating speed and a torque received by the plurality of accessories from the accessory drive by controlling a torque output of the motor generator,

the method comprises the acts of:

determining, with the motor-generator system controller, an operating state of the vehicle based on operating state information received from at least one of a vehicle sensor of the vehicle and another controller;

determining, with the motor-generator system controller, a current operating priority from the determined operating state, wherein the current operating priority is one of:

meeting safety requirements, including at least a requirement to maintain vehicle systems within system operating limits,

meeting energy storage requirements, said energy storage requirements comprising at least a requirement to maintain a state of charge of the energy storage above a first state of charge level,

satisfying a requirement for operating at least one accessory of the plurality of accessories at an accessory speed corresponding to a peak energy efficiency of the at least one accessory, an

Meeting driver comfort requirements including at least a requirement to maintain a climate condition of a passenger compartment of the vehicle within a desired temperature range;

determining an operating speed of each of the plurality of accessories required to satisfy the current operating priority;

selecting a highest operating speed among the operating speeds of the plurality of accessories required to satisfy the current operating priority when the accessory driver is operated by the motor generator;

determining from the highest operating speed a corresponding motor-generator speed required to produce the highest operating speed;

determining, from the corresponding motor-generator speed, operating speeds of remaining accessories of the plurality of accessories when operating at the corresponding motor-generator speed, the remaining accessories not including the accessory to be operated at the highest operating speed;

determining which of the remaining accessories is capable of meeting a respective accessory demand at a speed that is lower than an operating speed of the respective accessory produced at the corresponding motor-generator speed;

determining which of the remaining accessories is equipped with a separate clutch between the accessory drive and an accessory equipped with a separate clutch; and

controlling operation of the individual accessory clutches of the motor-generator and the remaining accessories in response to commands from the motor-generator system controller to control operation of the motor-generator and the remaining accessories

Controlling said motor-generator to said corresponding motor-generator speed, an

Adjusting the respective individual accessory clutch to adjust the operating speed of the respective remaining accessory to a lower speed at which the respective remaining accessory can meet a demand of the respective remaining accessory.

2. The method of claim 1, wherein,

the act of controlling operation of the motor-generator includes supplying electrical energy from the energy storage to the motor-generator.

3. The method of claim 2, wherein

The motor generator operates in an accessory drive mode at the following times

When the state of charge of the energy storage is higher than a third state of charge between the first state of charge and the second state of charge,

when the first state of charge is a predetermined low state of charge,

when the second state of charge is a predetermined high state of charge, an

When the third state of charge is a predetermined intermediate state of charge.

4. The method of claim 3, wherein,

the motor generator operates in an idle mode when the plurality of accessories have no torque demand on the motor generator.

5. The method of claim 3, wherein,

the first state of charge is a dynamically determined low state of charge,

the second state of charge is a dynamically determined high state of charge,

the third state of charge is a dynamically determined intermediate state of charge, and

the dynamically determined low state of charge, the dynamically determined high state of charge, and the dynamically determined intermediate state of charge are each determined based on at least one of a state of health of the energy storage and an energy storage environmental condition.

6. A method of operating a motor-generator accessory drive system of a vehicle, the motor-generator accessory drive system having

A motor-generator for generating a motor-generator,

a torque transfer section having a motor-generator end configured to receive the motor-generator and transfer torque between the motor-generator end and an accessory drive end of the torque transfer section,

an accessory drive coupled to the accessory drive end of the torque transmission section and arranged to be driven by the motor generator via the torque transmission and to drive a plurality of accessories,

an energy storage configured to store electric energy generated by the motor generator and to transfer the stored electric energy to the motor generator to generate torque output from the motor generator to the torque transfer section, an

A motor generator system controller configured to control at least one of an operating speed and a torque received by the plurality of accessories from the accessory drive by controlling at least one of an operating speed and a torque output of the motor generator,

the method comprises the acts of:

determining, with the motor-generator system controller, an operating state of the vehicle based on operating state information received from at least one of a vehicle sensor of the vehicle and another controller;

determining, with the motor-generator system controller, a current operating priority from the determined operating state, wherein the current operating priority is one of:

meeting safety requirements, including at least a requirement to maintain vehicle systems within system operating limits,

meeting energy storage requirements, said energy storage requirements comprising at least a requirement to maintain a state of charge of the energy storage above a first state of charge level,

satisfying a requirement for operating at least one accessory of the plurality of accessories at an accessory speed corresponding to a peak energy efficiency of the at least one accessory, an

Meeting driver comfort requirements including at least a requirement to maintain a climate condition of a passenger compartment of the vehicle within a desired temperature range;

determining a highest operating speed of the plurality of accessories when the accessory driver is operated by the motor generator at a motor generator speed sufficient to satisfy the current operating priority;

determining operating speeds of the remaining accessories of the plurality of accessories, the remaining accessories not including the accessory to be operated at the highest operating speed, when operating at the motor-generator speed sufficient to satisfy the current operating priority;

determining which of the remaining accessories is capable of meeting a respective accessory demand at a speed that is lower than an operating speed of the respective accessory produced at the corresponding motor-generator speed;

determining which of the remaining accessories is equipped with a separate clutch between the accessory drive and an accessory equipped with a separate clutch; and

controlling operation of the individual accessory clutches of the motor-generator and the remaining accessories in response to commands from the motor-generator system controller to control operation of the motor-generator and the remaining accessories

Controlling the motor generator to the motor generator speed sufficient to meet the current operating priority, an

Adjusting the respective individual accessory clutch to adjust the operating speed of the remaining accessories to a lower speed at which the remaining accessories can meet the requirements of the respective remaining accessories.

7. The method of claim 6, wherein,

the act of controlling operation of the motor-generator includes supplying electrical energy from the energy storage to the motor-generator.

8. The method of claim 7, wherein

The motor generator operates in an accessory drive mode at the following times

When the state of charge of the energy storage is higher than a third state of charge between the first state of charge and the second state of charge,

when the first state of charge is a predetermined low state of charge,

when the second state of charge is a predetermined high state of charge, an

When the third state of charge is a predetermined intermediate state of charge.

9. The method of claim 8, wherein,

the motor generator is operated in an idle mode when the at least one accessory has no torque demand on the motor generator.

10. The method of claim 8, wherein,

the first state of charge is a dynamically determined low state of charge,

the second state of charge is a dynamically determined high state of charge,

the third state of charge is a dynamically determined intermediate state of charge, and

the dynamically determined low state of charge, the dynamically determined high state of charge, and the dynamically determined intermediate state of charge are each determined based on at least one of a state of health of the energy storage and an energy storage environmental condition.

11. A method of operating a motor-generator accessory drive system of a vehicle, the motor-generator accessory drive system having

A motor-generator for generating a motor-generator,

a torque transfer section having a motor-generator end configured to receive the motor-generator and transfer torque between the motor-generator end and an accessory drive end of the torque transfer section,

an accessory drive coupled to the accessory drive end of the torque transmission section and arranged to be driven by the motor generator via the torque transmission and to drive a plurality of accessories,

an energy storage configured to store electric energy generated by the motor-generator and to transfer the stored electric energy to the motor-generator to generate torque output from the motor-generator to the torque transfer section,

a motor generator system controller configured to control at least one of an operating speed and a torque received by the plurality of accessories from the accessory drive by controlling a torque output of the motor generator,

the method comprises the acts of:

determining, for each accessory of the plurality of accessories, an operating speed required to meet a demand for the accessory by the vehicle;

determining an operating speed of the motor generator for each of the plurality of accessories to drive the accessory drive to generate the accessory operating speed required to meet the vehicle demand for the accessory, taking into account a gear ratio of each of the plurality of accessories;

identifying one or more of the plurality of accessories that need to be operated to meet critical safety requirements;

determining whether the one or more of the plurality of accessories that need to be operated to meet the critical safety requirement have a highest determined motor-generator operating speed;

if the one or more of the plurality of accessories that need to be operated to meet the critical safety requirement have the highest determined motor-generator operating speed, then

Selecting the highest determined motor-generator speed as the current motor-generator operating speed,

determining operating speeds of the remaining accessories from the current motor-generator speed when operating at the current motor-generator speed, the remaining accessories not including the accessory requiring the highest determined motor-generator operating speed;

determining which of the remaining accessories is capable of meeting a respective accessory requirement at a speed lower than an operating speed of the respective accessory at the current motor-generator speed; and

determining which of the remaining accessories is equipped with a separate clutch between the accessory drive and an accessory equipped with a separate clutch;

if the one or more of the plurality of accessories that need to be operated to meet the critical safety requirement do not have the highest determined motor-generator operating speed, then

Determining, with the motor generator system controller, a second operational priority from the determined operational state, wherein the second operational priority is one of:

meeting safety requirements, including at least a requirement to maintain vehicle systems within system operating limits,

meeting energy storage requirements, said energy storage requirements comprising at least a requirement to maintain a state of charge of the energy storage above a first state of charge level,

meeting a requirement for operating the at least one accessory at an accessory speed corresponding to a peak energy efficiency of the at least one accessory, an

Meeting driver comfort requirements including at least a requirement to maintain a climate condition of a passenger compartment of the vehicle within a desired temperature range,

setting the current motor-generator operating speed to a speed that meets the second operational priority while also meeting the critical safety requirements,

determining which of the plurality of accessories is equipped with a separate clutch between the accessory drive and the accessory equipped with a separate clutch, an

Determining which of the plurality of accessories is capable of meeting a respective accessory requirement at a speed lower than an operating speed of the respective accessory at the current motor-generator speed while also meeting the critical safety requirement and the second operating priority,

controlling, in response to a command from the motor generator system controller, operation of the motor generator and the individual accessory clutches of the remaining accessories, excluding the one of the plurality of accessories that is operating at the current motor generator speed to satisfy the second operating priority, so as to

Controlling said motor-generator to said corresponding motor-generator speed, an

Adjusting the respective individual accessory clutch to adjust the operating speed of the remaining accessories equipped with individual clutches to the lower speed at which the accessories are able to meet the respective accessory demand.

12. The method of claim 11, wherein,

the act of controlling operation of the motor-generator includes supplying electrical energy from the energy storage to the motor-generator.

13. The method of claim 12, wherein

The motor generator operates in an accessory drive mode at the following times

When the state of charge of the energy storage is higher than a third state of charge between the first state of charge and the second state of charge,

when the first state of charge is a predetermined low state of charge,

when the second state of charge is a predetermined high state of charge, an

When the third state of charge is a predetermined intermediate state of charge.

14. The method of claim 13, wherein,

the motor generator is operated in an idle mode when the at least one accessory has no torque demand on the motor generator.

15. The method of claim 13, wherein,

the first state of charge is a dynamically determined low state of charge,

the second state of charge is a dynamically determined high state of charge,

the third state of charge is a dynamically determined intermediate state of charge, and

the dynamically determined low state of charge, the dynamically determined high state of charge, and the dynamically determined intermediate state of charge are each determined based on at least one of a state of health of the energy storage and an energy storage environmental condition.

16. A method of operating a motor-generator accessory drive system of a vehicle, the motor-generator accessory drive system having

A motor-generator for generating a motor-generator,

an accessory drive arranged to be driven by the motor generator and to drive a plurality of accessories,

an energy storage configured to transfer stored electric energy to the motor-generator to generate torque output from the motor-generator to the torque transfer section, an

A motor generator system controller configured to control at least one of an operating speed and a torque received by the plurality of accessories from the accessory drive by controlling a torque output of the motor generator,

the method comprises the acts of:

determining, with the motor-generator system controller, an operating state of the vehicle based on operating state information received from at least one of a vehicle sensor of the vehicle and another controller;

determining, with the motor-generator system controller, a current operating priority from the determined operating state, wherein the current operating priority is one of:

meeting safety requirements, including at least a requirement to maintain vehicle systems within system operating limits,

meeting energy storage requirements, said energy storage requirements comprising at least a requirement to maintain a state of charge of the energy storage above a first state of charge level,

satisfying a requirement for operating at least one accessory of the plurality of accessories at an accessory speed corresponding to a peak energy efficiency of the at least one accessory, an

Meeting driver comfort requirements including at least a requirement to maintain a climate condition of a passenger compartment of the vehicle within a desired temperature range;

determining an operating speed of each of the plurality of accessories required to satisfy the current operating priority;

selecting a highest operating speed among the operating speeds of the plurality of accessories required to satisfy the current operating priority when the accessory driver is operated by the motor generator;

determining from the highest operating speed a corresponding motor-generator speed required to produce the highest operating speed;

determining, from the corresponding motor-generator speed, operating speeds of remaining accessories of the plurality of accessories when operating at the corresponding motor-generator speed, the remaining accessories not including the accessory to be operated at the highest operating speed;

determining which of the remaining accessories is capable of meeting a respective accessory demand at a speed that is lower than an operating speed of the respective accessory produced at the corresponding motor-generator speed;

determining which of the remaining accessories is equipped with a separate clutch between the accessory drive and an accessory equipped with a separate clutch; and

controlling operation of the individual accessory clutches of the motor-generator and the remaining accessories in response to commands from the motor-generator system controller to control operation of the motor-generator and the remaining accessories

Controlling said motor-generator to said corresponding motor-generator speed, an

Adjusting the respective individual accessory clutch to adjust the operating speed of the respective remaining accessory to a lower speed at which the respective remaining accessory can meet a demand of the respective remaining accessory.

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