WO2010151742A1

WO2010151742A1 - Hybrid vehicle having a transmission coupling between engine and generator

Info

Publication number: WO2010151742A1
Application number: PCT/US2010/039948
Authority: WO
Inventors: Paul Boskovitch; Axel J. Radermacher
Original assignee: Fisker Automotive, Inc.
Priority date: 2009-06-25
Filing date: 2010-06-25
Publication date: 2010-12-29

Abstract

A vehicle including an electric machine and an engine coupled to the electric machine, A transmission is disposed between the electric machine and the engine providing a transmission speed ratio operable to allow the electric machine operating speed to operate independent of engine operating speed.

Description

CROSS-REFERENCE TO RLEATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/220,421 , filed June 25. 2009, the disclosures of which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] The present disclosure relates generally to a hybrid vehicle, and more particularly to a hybrid vehicle having multi-speed coupling between the engine and generator.

DESCRIPTION OF THE RELATED ART

[0003] Vehicles, such as a motor vehicle, utilize an energy source in order to provide power to operate a vehicle. While petroleum based products dominate as an energy source, alternative energy sources are available, such as methanol, ethanol, natural gas, hydrogen, electricity, solar or the like. A hybrid powered vehicle utilizes a combination of energy sources in order to power the vehicle. Such vehicles are desirable since they take advantage of the benefits of multiple fuel sources, in order to enhance performance and range characteristics of the hybrid vehicle relative to a comparable gasoline powered vehicle. An example of a hybrid vehicle is a vehicle that utilizes both electric and gasoline as a power source.

000139718\0309\1149132-1 [0004] An electric vehicle is environmentally advantageous due to its iow emissions characteristics and general availability of electricity as a power source. However, battery storage capacity limits the performance of the electric vehicle relative to a comparable gasoline powered vehicle.

[0005] The hybrid vehicle may include an engine that drives an electric machine in order to produce electrical power. However, the engine is frequently operating at conditions whereby the optimized engine condition, such as speed or torque, does not match the optimized electric machine operating condition. As a result, fuel consumption increases and larger more expensive components may be required to satisfy power demands. Thus, there is a need in the art for a hybrid electric powered vehicle that includes a transmission between the engine and electric machine to improve system operating efficiency of the engine and electric machine by controlling the relative speeds therebetween.

SUMMARY

[0006] Accordingly, the present disclosure relates to a vehicle including: (a) an electric machine; (b) an engine coupled to the electric machine; and (c) a transmission disposed between the electric machine and the engine providing a transmission speed ratio operable to allow the electric machine operating speed to operate independent of engine operating speed.

[0007] An advantage of the present disclosure is that a hybrid vehicle is provided that includes an engine, an electric machine, and a transmission disposed

000139718\0309\1 149132-1 therebetween. Another advantage of the present disclosure is that the operating efficiency of the electric machine is improved, resulting in decreased fuei consumption. A further advantage of the present disclosure is that the size of the engine and electric machine can be reduced due to the improved operating efficiency. [0008] Other features and advantages of the present disclosure will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FiG. 1 is a top view of a powertrain architecture for a hybrid electric vehicle. FIG. 2 is a block diagram of a hybrid vehicle architecture having an electric machine, a transmission, and an engine.

[0011] FiG. 3A is a graph of operating efficiency of the engine with respect to the electric machine for [he hybrid vehicle of FIG. 2 having a transmission speed raϋo of

1.5.

[0012] FIG. 3B is a graph of operating efficiency of the engine with respect to the electric machine for the hybrid vehicle of FIG. 2 having a transmission speed ratio of

1.0.

[0013] FiG. 3C is a graph of operating efficiency of the engine with respect to the electric machine for the hybrid vehicle of FIG. 2 having a transmission speed ratio of

0.5.

000139718\0309\1 149132-1 The present disclosure provides for a system and method of electrical split gear transmission (e-split) between an engine and an electric machine such as a generator or a motor. Referring to FIGS. 1-3, a hybrid vehicle 10 is illustrated. In this example the vehicle 10 can be a plug-in hybrid vehicle powered by an internal combustion engine 20 and a battery 16 operable to be charged off-board. Both the engine 20 and the battery 16 can function as a power source for the vehicle 10. The vehicle 10 can be powered by each power source independently or in cooperation. A hybrid vehicle that uses a series configuration, such as an engine driving a generator and the generator providing electrical power to a drive motor, can utilize this architecture. The vehicle 10 could be a passenger vehicle, truck, off-road equipment, etc.

Vehicle 10 also includes a drivetrain 11 that operatively controls movement of the vehicle. A motor 24 that mechanically drives wheels W of the vehicle is powered by the power sources (i.e., a battery and/or generator), in the example of FIG. 1 , vehicle 10 is a rear wheel drive vehicle with rear wheels W mechanically driven by motors 24. Motors 24 and generator 12 can be referred to as an electric machine ("EM"), In an example, the terms "motor" and "generator" are interchangeable since each can be operated in reverse to accomplish the opposite function. Therefore, an EM can either generate power by operating with a negative shaft torque (i.e., a generator) or distribute power by producing positive shaft torque (i.e., a motor).

000139718\0309\1 149132-1 The architecture of the drive train is selectively determined, such as a series, parallel or parallel-split arrangement of the drive train components. In this example, as shown in FIG. 2, the drive train includes an EM 12. Various types of EM 12 are available, such as an electric motor, or generator, or the like. The EM 12 can include a housing, a stator disposed in the housing that is stationary, and a rotor that rotates about a centra! shaft that includes a permanent magnet. The EM converts mechanical energy received from engine 20 to electrical energy used to provide power to the wheels, charge the on-board battery 16, or power auxiliary vehicle components. Typically, the output of EM 12 is A/C power that is converted to D/C power in an inverter 22. The D/C power can then either be delivered to the battery 16 or another inverter 22 to convert back to A/C power before powering any drive motors. Typical of such EMs, each has a predetermined operating efficiency corresponding to a given speed/torque band.

In this example, the drivetrain 11 also includes a gasoline powered engine 20 that provides supplemental power when required under certain operating conditions. In this example, the engine 20 is a gasoline engine. Engine 20 is operatively coupled to EM 12, such as via an engine output shaft. Accordingly, when the engine 20 runs, the EM 12 typically runs as a result of their engagement to each other. The engine 20 can also have a predetermined operating efficiency at a corresponding speed/torque band. However, the ratio of engine speed efficiency with respect to generator speed efficiency may not be optimal within a particular speed band.

000139718\0309\1 149132-1 [0018] The drivetrain 11 includes a transmission 14 disposed between EM 12 and engine 20. in an example, transmission 14 provides a mechanical linkage between the engine 20 and electric machine 12 in line with the engine output shaft. The transmission may be of any type, such as electronic, mechanical or electro-mechanical, and can be a multi-speed or continuously variable transmission, or the like to offer selectable effective gear ratios. The transmission varies the gear ratios, to facilitate the transfer of engine power to the generator. For example, it may be desired to run engine 20 at 3000 rpm and EM 12 at 4500 rpm. Transmission 14 positioned between engine 20 and EM 12 can allows each of the engine 20 and EM 12 to independently operate at a desired speed and/or torque for a corresponding speed band. Engine 20 and EM 12 can each define different torque/speed efficiency profiles. Allowing each to operate at different speeds can allow optimization by adjusting transmission ratio selection to operate each component as close to its corresponding speed identifiable from a measured efficiency map. FIG. 3 illustrates an example efficiency map associated with various exemplary transmission ratios between the speed of the engine 20 and the EM 12.

Various types of transmissions 14 may be utilized, such as a multi-speed transmission or continuously variable transmission, or the like. The transmission 14 may incorporate multiple gear sets between the engine 20 or EM 12. Similarly, transmission 14 may utilize planetary gears. An arrangement of transmission 14 between engine 20 and EM 12 may be incorporated with many different hybrid

000139718\0309\1 149132-1 powertrain architectures. Transmission 14 allows for more efficient system operation as compared to a standard powertrain without a transmission. As a result of the enhanced efficiency, excess power may result and be supplied to an external component while the vehicle is parked. In an example, the vehicle can store excess power and distribute that power to an external source such as a grid or an externa! energy storage device.

[0020] As described, the EM 12 operating speed may be independent of the engine 20 operating speed. As a result, the use of a transmission 14 therebetween to control the transfer of power through different transmission ratios, the efficiency of the system can be enhanced. FIGS. 3A-3C further illustrate some improved operating efficiency profiles of EM 12. The operating efficiency profiles provides an engine designer with increased freedom in selecting the various engine operating points corresponding with predetermined vehicle operating conditions.

Referring to the graphs of FIGS. 3A-3C, the horizontal x-axis represents engine speed and the vertical y-axis represents load or torque. Thus, an EM capable of lower torque characteristics can be selected, since the constant power operating region of the EM can still be utilized thereby still exhibiting the same performance. The graphs illustrate how variable speeds between the engine and EM can align the maximum efficiency of the EM with the current operating point of the engine.

[0022] In these examples, the EM is a generator operating at different efficiencies. FiG. 3A shows a graph versus speed versus torque for a transmission ratio of 1.5 of the

000139718\0309\1 149132-1 generator compared to the engine with the generator torque shown as sensed by the engine through the transmission. The transmission ratio is set at a particular ratio and the engine and generator adjust speed when sensing speed change from the other through the transmission, In an exampie, the change in speed can be sensed by an input shaft on the engine side of the transmission, In FIGS. 3A-3C, the engine efficiency curves are held while varying the generator as sensed through the transmission and the different transmission ratios.

Engine torque profiles are also shown. In this example, the engine efficiency points of 20%, 30%, and 33% each define a curve on the graph. The generator efficiency points of 80% and 90% each define a curve on the graph: 80% efficiency curve 37 and 90% efficiency curve 39. A Peak torque engine curve 31 and a peak torque generator curve 33 is represented for each component at the given transmission speed ratio of 1.5, In this example, the engine reaches a maximum torque of about 350 Newton-meters (N-m) and the generator reaches a maximum torque of about 360 N-m.

An area on the graph formed above an engine 20% efficiency curve 30 and below the peak engine torque curve 31 provides various operating conditions of speed and torque for the engine running at about at least 20% efficiency. The engine 30% efficiency curve 32 and the peak engine torque curve 31 form an operating area in which the engine will run given the speed and torque with about or greater than 30% efficiency. A further operating area is formed by the engine 33% efficiency curve 34. The area formed by curve 34 is fully captured within the area above curve 32 and curve

000139718\0309\1 149132-1 30. The area formed by curve 34, provides a map or profile for operating the engine at a relatively higher efficiency and the available torque and speed characteristics thai can be reached by the vehicle with efficiency at about at least 33%. In this example, at data point 35, the engine is operating at 33% efficiency and capable of reaching a torque of approximately 320 N-m. The engine speed at point 35 is just above 2000 rpm. The corresponding generator efficiency at [his point is at a low and between 80% and 90% efficient.

FiG. 3A also provides a speed and torque profile for a generator operating at a transmission ratio of 1.5 times the speed of the engine. For example, if the engine is operating at 1000 rpm, then the generator is operating at 1500 rpm as a result of the transmission disposed therebetween. An area on the graph is formed below the peak generator torque curve 33 and above each of the example generator efficiency curves 37 and 39. The area formed above curve 39 provides for operating the generator at a relatively higher efficiency, (i.e., 90%) and the available torque and speed characteristics that can be reached by the vehicle. In this example, the vehicle can operate with the generator at 90% if the engine is running at relatively low efficiencies and the speed of each of the engine and the generator is above 6000 rpm. If the engine is operating at 30% or 33% efficiency, then the generator is operating close to about 80% efficiency as shown in the chart of FIG. 3A.

6] FIG. 3B illustrates an efficiency map for a transmission ratio of 1.0. The engine efficiency curves 30, 31 , 32, and 34 remain unchanged. The generator curves,

000139718\0309\1 149132-1 as sensed by the engine, are different for a ratio of 1.0 as compared to 1.5. A peak generator curve 133 allows for a much higher torque at a lower speed for the 1.0 ratio as compared to the peak generator curve 33 of the 1.5 ratio of FIG. 3A. A generator 80% efficiency curve 137 allows for running the engine at the higher efficiencies of 30% and 33% as well as 20%. At a transmission ration of 1.0, the generator can operate at 90% efficiency for an engine operating at 30% efficiency as the areas formed by curve 139 and 32 overlap.

[0027] FiG. 3C illustrates an efficiency map for a transmission ratio of 0.5 where the generator spins twice as fast as the engine. The engine efficiency curves 30, 31 , 32, and 34 remain unchanged. The generator curves are different for a ratio of 0.5 as compared to a ratio of 1.5 or 1.0 as sensed by the engine. A peak generator curve 233 aliows for a much higher torque at a iower speed for the 0.5 ratio as compared to the peak generator curve 33 or 133 of the 1.5 ratio of FIG. 3A or the 1.0 ratio of FlG. 3B respectively. A generator 80% efficiency curve 237 allows for running the engine at the higher efficiencies of 30% and 33% as well as 20%. At a transmission ration of 0.5, the generator can operate at 90% efficiency for an engine operating at 30% efficiency or 33% efficiency as the areas formed above curve 239 and 34 or 32 overlap.

The examples disclosed in FIGS. 3A-3B relate to engine and generator efficiency strategy and comparison. Further benefits include that the transmission between the engine and generator gives a powertrain designer greater freedom in generator and/or engine design or selection, because the engine/generator relative

000139718\0309\1 149132-1 torque/speed relationship is adjustable. For example, a low torque high speed generator can be coupled to [he engine with no loss of function or performance as long as power requirements are met,

[0029] The drivetrain may include other components that are known in the art. For example, a clutch, such as a wet or dry clutch, may be located on the shaft of the engine to switch between different speed ratios. Additional powertrain component may be included and are consistent with the operation of the vehicle.

[0030] Various types of batteries 16 are available, such as lead acid, or lithium-ion or the like. It should be appreciated that the vehicle may include more than one type of battery or energy storage device. The battery supplies the power in the form of electricity to operate various vehicle components. In this example the electricai energy power management system includes a low voltage battery that provides electrical power to vehicle components and a high voltage battery (i.e. 400 V traction battery) that provides electrical power to the electric drive motor. The battery may be in communication with a controller 13that regulates the distribution of power within the vehicle, such as to the electric drive motor, or a vehicle component or other accessories or the like as part of the electrical energy power management system, in an example, the high voltage battery receives electrical energy from a plug-in source, and the low voltage battery receives electricai energy from a solar source.

000139718\0309\1 149132-1 The powertrain 1 1 may include other components, such as a battery electronic control module (BECM) that monitors the status and controls state of charge of the batteries. \t may also include a hybrid control unit (HCU), which is a controller 13that controls the high voltage contactors, such as the high voltage interlock. The HCU may interface with other controllers, such as a vehicle control module (VCM) or BECM. The VCM can manage the distribution of power between different energy sources such as the engine and the battery.

[0032] In an example, the system can sense generator/motor speed using a sensor, and engine speed using a sensor. Each of the speed signals are sent to a processor. Logic within the processor evaluates both speed signals and transmits a signal to the transmission to selectively control the transmission gears to further control the transfer of engine power to the generator/motor. As a result, the generator/motor can operate at a speed that is independent of the engine speed in order to deliver suitable system efficiency. As a result of these efficiencies, a vehicle designer has increased freedom in the selection of the engine operating points for maximizing system efficiency.

In a further example, the present disclosure allows for improved cold starting the vehicle. Under cold ambient temperature conditions, it may be difficult to start the engine. At relatively lower temperatures the battery may have little power and the oil in the engine can be thick which makes it difficult to start the vehicle. By allowing the generator to drive the engine at different ratios, a higher cranking torque can be applied.

000139718\0309\1 149132-1 Many modifications and variations of the present disclosure are possibie in light of the above teachings. Therefore, within the scope of the appended claim, the present disclosure may be practiced other than as specifically described.

000139718\0309\1 149132-1

Claims

1. A vehicle comprising:

(a) an electric machine;

(b) an engine coupled to the electric machine; and

(c) a transmission disposed between the electric machine and the engine providing a transmission speed ratio operable to allow the electric machine operating speed to operate independent of engine operating speed.

2. The vehicle of claim 1 , wherein the transmission is a variable speed transmission.

3. The vehicle of claim 1 , wherein the transmission includes a plurality of speed ratios allowing the engine and the electric machine to operate at different speeds corresponding to the transmission speed ratio.

4. The vehicle of claim 1 , wherein the transmission speed ratio ranges from 0.5 to 4.0.

5. The vehicle of claim 1 , wherein the transmission speed ratio ranges from 0.5 to 1.

6.

000139718\0309\1 149132-1

8. The vehicle of claim 1 , wherein the plurality of speed ratios includes a ratio of electric machine speed to engine speed that is selected from the ratios of 1.0, 1.5 and 0.5,

7. The vehicle of claim 1 , further comprising at least a clutch disposed between the engine and [he transmission adapted to adjust a setting on [he transmission.

8. The vehicle of claim 1 , further comprising a vehicle controller coupled to the transmission to adjust the transmission speed ratio.

9. The vehicle of claim 8, wherein the vehicle receives engine speed and electric machine speed data from an engine speed sensor and an electric machine speed sensor and adjusts the transmission speed ratio according to the received speed data reaching preset thresholds.

10. The vehicle of claim 1 , wherein the electric machine is a generator.

11. The vehicle of claim 10, wherein the generator is adapted to deliver power to a drive motor of the vehicle.

12. The vehicle of claim 11 , wherein an inverter is disposed between the generator and the drive motor.

000139718\0309\1 149132-1

13. The vehicle of claim 1 , wherein the engine is a 6,000 rpm engine.

14. The vehicle of claim 1 , wherein the electric machine is a 10,000 rpm generator.

15. The vehicle of claim 1 , wherein the engine is adapted to operate at an efficiency selected from the group consisting of 20% efficient, 30% efficient, and 33% efficient.

16. The vehicle of claim 1 , wherein the electric machine is adapted to operate at an efficiency selected from the group consisting of 80% efficient and 90% efficient.

17.A method for managing engine speed of a hybrid electric vehicle comprising the steps of:

(a) providing a transmission between an engine of the vehicle and an electric machine of the vehicle;

(b) selecting a predetermined transmission speed ratio of engine speed to electric machine speed;

(c) operating the engine of the vehicle at a first speed:

(d) operating the electric machine of the vehicle at a second speed according to the transmission speed ratio.

000139718\030'Λ1 149132-1

18. The method of claim 17, wherein the transmission speed ratio ranges from 0.5 to 4.0.

19. The method of claim 17, further comprising the steps of adjusting the transmission speed ratio with a vehicle controlier coupled to the transmission.

20. The method of claim 17 further including the step of adjusting the transmission speed ratio according to the received speed data reaching a preset threshold, wherein the vehicle receives engine speed and electric machine speed data from an engine speed sensor and an electric machine speed sensor.

000139718\0309\1 149132-1