Compact electric range extender device for an electric vehicle

Abstract

Electric vehicle (10), which includes: a gearbox (14) with an input element (140); an electric traction motor (12) with a motor output shaft (15) which is mechanically coupled to the input element (140); a rechargeable energy storage system (RESS) (18) which is electrically connected to the electric traction motor (12); an auxiliary power unit (APU) (50) with: a set of induction coils; an outer ring (22); an inner ring (20) which is coaxial to the outer ring (22) and is positioned radially inside the same, wherein the outer ring (22) and / or the inner ring (20) is / are rotatable with respect to the other in order to generate an electric current in the set of induction windings; a gear element (26) in a driving connection with the outer ring (22) or inner ring (20) which rotates; a power machine (40) arranged radially within the inner ring (20) and containing a power extraction mechanism (24) mechanically coupled to the transmission element (26); and a controller (30) in electrical connection with the APU (50) and the RESS (18); wherein the controller (30) can be operated to detect when a level of energy available in the RESS (18) falls below a calibrated threshold, and to selectively excite the APU (50) to generate electrical power via the rotation of the outer ring (22) and / or the inner ring (20) whenever the energy available in the RESS (18) falls below the calibrated threshold; wherein, in the event of a regenerative braking event or any other event in which mechanical energy can be converted into electrical energy, an angular momentum can be stored in one or both rings (20, 22) for a slower return of electrical energy to the rechargeable energy storage system (18).

Description

TECHNICAL AREA

[0001] The present disclosure relates to the generation of electrical auxiliary power on board an electric vehicle. BACKGROUND

[0002] Electric vehicles use a high-voltage electric traction motor to deliver motor torque at levels sufficient to start and propel the vehicle. Electrical energy is alternately stored in and drawn from a rechargeable energy storage system (RESS). The RESS is typically recharged during operation through regenerative braking or another regenerative event. When the vehicle is parked, the RESS can be recharged using an external power source, such as a wall outlet or a charging station. Unlike hybrid electric vehicles, which can rely on an internal combustion engine to provide engine torque to propel the vehicle, the range of electric vehicles is limited by the energy stored in the RESS.

[0003] German patent application DE 43 41 817 C2 discloses a hybrid vehicle system comprising an electric drive motor coupled to a transmission, a rechargeable energy storage system, an auxiliary power unit and a controller, wherein the controller excites the auxiliary power unit when the energy available in the rechargeable energy storage system falls below a threshold.

[0004] In the publication DE 40 20 176 A1, a power unit is disclosed which comprises an annular stator, an annular rotor with induction windings arranged radially coaxially therein, an internal combustion engine arranged radially inside the annular rotor for driving the rotor and a gear element for driving the rotor.

[0005] Document DE 38 43 673 A1 discloses a power supply system for motor vehicles that can be housed in a spare wheel container.

[0006] Publication US 8 662 052 B2 discloses a power generator that uses a Wankel engine as a drive module. SUMMARY

[0007] An electric vehicle is disclosed herein. The electric vehicle incorporates an auxiliary power unit (APU). The APU is switched on as needed to generate electrical energy and thereby extend the vehicle's range. The use of the present APU, configured and packaged as disclosed herein, can help reduce range concerns by enabling a degree of electric driving when the energy available from a vehicle's energy storage system (RESS) falls below a certain threshold, for example, by allowing a driver to travel to a power outlet or charging station.

[0008] Specifically, an electric vehicle is disclosed here, comprising a transmission, an electric traction motor, the APU, a RESS, and a controller. The traction motor has a motor output shaft that is mechanically coupled to an input element of the transmission. The transmission is powered exclusively by electrical energy from the traction motor.

[0009] The APU contains a pair of rings. One ring can be connected to a stationary surface of the vehicle or grounded, such as the wall of a spare tire well or other compartment. Another ring, or optionally both rings, can rotate whenever the power unit is supplied with fuel. A gear element is in a driving connection with the inner ring and with the power unit itself.

[0010] The power unit can have various configurations, as disclosed here. Regardless of the configuration, the power unit has a reduced axial dimension, for example, a flattened or pancake-like design, and is arranged radially within the inner ring. A power extraction mechanism belonging to or associated with the power unit is mechanically coupled to the transmission element, for example, via a drive belt, chain, clutch, or other direct or intermittent connection device. The controller communicates electrically with the APU and the RESS and selectively excites the APU via the RESS when the level of available energy from the RESS falls below a calibrated threshold.

[0011] During a regenerative braking event or any other event where mechanical energy can be converted into electrical energy, angular momentum can be stored in one or both rings for slower feedback of electrical energy to the rechargeable energy storage system.

[0012] A method is also disclosed which includes positioning an auxiliary power unit (APU) in a compartment defined by the body of an electric vehicle. This step includes attaching an outer ring of induction windings to a wall of the compartment, positioning a rotatable inner ring with permanent magnets radially inside and coaxial to the outer ring, and positioning an internal combustion engine radially inside the rotatable inner ring. The method then includes connecting a power extraction mechanism of the engine to the rotatable inner ring.

[0013] The foregoing features and advantages and other features and advantages of the present invention will be readily apparent from the following detailed description of the best ways of carrying out the invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a schematic block diagram of an exemplary electric vehicle with an auxiliary power unit (APU) that can be selectively operated to increase the electric range of the vehicle. Fig. 2 is a schematic representation of an exemplary APU, which is connected to the one in Fig. The electric vehicle shown can be used. Fig. Figure 3 is a flowchart illustrating an exemplary procedure for selectively increasing the electric range of the vehicle. Fig. 1 using the in Fig. 2 shows the APU shown. DESCRIPTION

[0014] With reference to the drawings, in which identical reference numerals correspond to identical or similar components in the multiple figures, an electric vehicle 10 in Fig. Figure 1 is shown schematically. Vehicle 10 contains an auxiliary power unit (APU) 50, an example of which is shown in Figure 1. Fig. 2 is shown and described in detail below. Furthermore, the vehicle 10 includes an electric traction motor 12 with a motor output shaft 15, which is coupled to an input element 140 of a gearbox 14. Torque from the traction motor 12 ultimately drives wheels 21 of one or more drive axles 19 via an output element 17 of the gearbox 14.

[0015] The electric vehicle 10 includes a body 27 that defines a compartment 25. In a specific embodiment, the APU 50 can be located entirely within the compartment 25. In an exemplary embodiment without restriction, the compartment 25 can be a spare wheel container located in a rear or trunk section of the vehicle 10 or at another suitable location. Alternatively, the APU 50 can be connected under or above the vehicle 10, outside the body 27, using a suitable support structure (not shown).

[0016] The APU 50 can be designed with limited axial space, for example, an axially flattened / pancake-like device that fits within the relatively shallow confines of a spare wheel well. In other words, the APU 50 has a low aspect ratio mounting scheme sufficient to mount or position the APU 50 on board the vehicle 10 in a location that might otherwise accommodate a spare wheel or other cargo, or for mounting in locations with limited space that are not otherwise occupied by propulsion components.

[0017] The electric traction motor 12 can be designed as a multi-phase machine, depending on the embodiment, for example, from about 60 VAC to about 300 VAC or more. In such an embodiment, the traction motor 12 can be electrically connected via a rectifier / inverter module (PIM) 16 to a rechargeable energy storage system (RESS) 18, which ultimately converts AC power generated by the traction motor 12 or during regenerative braking into DC power suitable for storage in the RESS 18.

[0018] Other embodiments can configure the traction motor 12 as a DC motor that does not require the PIM 16. In each embodiment, an auxiliary power module (APM) or a DC / DC converter (not shown) can be used to supply the required DC output voltage to the various devices, as is understood in the art. Regardless of the configuration, the RESS 18 can selectively receive power from the APU 50 as determined by a vehicle-integrated controller 30 (arrow 11).

[0019] Still referring to Fig. 1. The controller 30 is connected to the APU 50 via control and feedback signals (arrow 31) in a closed and / or open control loop. The controller 30 can be configured as one or more digital computers comprising a central processing unit (CPU), sufficient read-only memory (ROM), flash memory, random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a high-speed clock, analog-to-digital (A / D) and / or digital-to-analog (D / A) circuits, and any required input / output circuits and associated devices, as well as any necessary signal conditioning and / or signal buffering circuits. The controller 30 can contain instructions suitable for carrying out the present method 100 (see Fig. 3) to carry out and to determine the level of available energy in the RESS 18, e.g. by receiving signals (arrow 33) indicating such remaining energy, regardless of whether such a level is measured, calculated or determined by other means.

[0020] With reference to Fig. Figure 2 shows an exemplary APU 50 schematically such that it includes an axially reduced power unit 40. The power unit 40 is arranged radially within a pair of concentric rings 20, 22. At least one of the rings 20, 22 can rotate relative to the other, the identity of the ring that actually rotates depending on the design. In one possible embodiment, the ring 22 can be attached to a stationary element of the vehicle 10. Fig. 1 be attached, e.g. to a radial wall 52 of the in Fig. 1 shown compartment 25. The ring 22 can be fastened by means of weld points 54 or another suitable means. In this embodiment, the ring 20 is arranged radially inside the ring 22 and aligned coaxially with it. For clarity, the ring 20 will therefore be referred to below as the inner ring 20 and the ring 22 as the outer ring 22.

[0021] In the embodiment shown, the inner ring 20 contains a plurality of permanent magnets 58. The magnets are oriented towards the outer ring 22. The outer ring 22 contains a coil or is configured as a set of conductive coils or induction windings. For example, rotation of the inner ring 20 generates an electric current in the induction windings that belong to or completely form the inner ring 20. The opposite effect will occur in an embodiment in which the outer ring 22 can rotate and the inner ring 20 is held stationary, as is well understood in the art. The generated current is finally connected to the PIM 16 and / or the RESS 18. Fig. 1 as electrical energy (arrow 11), as shown in the same figure. The inner ring 20 can optionally be designed with air-conducting fins (not shown) or channels to allow air to circulate freely during rotation of the inner ring 20, thereby cooling the power machine 40.

[0022] The Power Machine 40 from Fig. 2 includes a power extraction mechanism 24, for example a rotatable pulley or gear set, which rotates about an axis of rotation 80 with a power machine torque (arrow T) E) rotates. Power machine mounts 13 can be used to support the weight of the power machine 40. The power extraction mechanism 24 is mechanically coupled to a transmission element 26, for example via a chain or drive belt 60, or temporarily, e.g. via a clutch, such that a rotation of the power extraction mechanism 24 ultimately transmits a rotor torque (arrow T) to the transmission element 26. R ) rotates. The gear element 26 can be toothed with the inner ring 20 or otherwise engaged to provide sufficient drive engagement.

[0023] Various embodiments are possible for the present power unit 40. Packaging and weight are important design considerations. The compartment 25 can therefore define at least a portion of a channel 28 between the power unit 40 and the environment, e.g., a channel, a pipe, or another fully enclosed passage. Such a channel 28, or several such channels 28, can be configured to allow exhaust gas (arrow 45), air intake, fuel supply, and / or power unit cooling.

[0024] In an exemplary embodiment, the power engine 40 can be a heat engine comprising a plurality of cylinders 35. Each of the cylinders 35 can have a longitudinal axis 110, 210 which intersects the axis of rotation 80 of the power extraction mechanism 24. Such a power engine 40 can comprise a multi-cylinder in-line engine or a flat piston-cylinder engine of the "V" or "W" type. Alternatively, the use of the piston / cylinder approach can be omitted, and a rotary engine of the Wankel type can be used instead. As is understood in the art, such a power engine uses a gerotor design with three cams and eccentric shafts, similar to a rotor arrangement, to convert pressure into torque without the use of pistons.

[0025] Other possible embodiments include single-cylinder engines, steam-driven engines, or turbine-driven devices. In fact, a piston-driven heat engine with any number of cylinders is possible. Examples include a single-cylinder, a two-cylinder V-engine, or a flat three-cylinder or four-cylinder engine, the latter two having a power extraction gear with a 90° rotation angle for proper coupling with the transmission system that converts a rotation of the heat engine into a ring rotation. Energy conversion devices can be used, such as an external combustion engine or a turbine. In a turbine example, the turbine can be driven by pressurizing an internal fluid, e.g.,Power is supplied via combustion, by pressurizing an external fluid using external combustion, or by a previously pressurized tank of compressed air.

[0026] With reference to Fig. Figure 3 shows an exemplary method 100 to increase the range in electric operation of the in Fig. 1 electric vehicle shown 10 or any vehicle that is equipped with the in Fig. The APU 50 shown in Figure 2 is equipped to selectively enlarge the process. Method 100 begins with step S102, in which the APU 50 is positioned in a compartment defined by the body of an electric vehicle, e.g., a spare wheel compartment. Step S102 may include attaching at least one of the rings 20 and / or 22 to a stationary element, e.g., attaching the outer ring 22 of induction windings to a wall 52 of the compartment 25, as shown in Figure 2. Fig. Figure 2 shows that the windings are then connected to the RESS 18, with step S102 comprising positioning the inner ring 20 with its permanent magnets radially inside and coaxially with the outer ring 22. Step S102 may also comprise positioning the power machine 40 radially inside the rotatable inner ring 20 and then connecting the power extraction mechanism 24 of the power machine 40 to the rotatable inner ring 20.

[0027] At step S104, the controller determines 30 of Fig. 1. The energy available in the RESS 18, e.g., by measuring or calculating this value. The controller 30 compares the available energy of the RESS 18 with a calibrated threshold value, which may be stored in the controller 30's memory. The controller 30 repeats step S102 if the detected or calculated energy value exceeds the calibrated threshold value. Otherwise, the controller 30 proceeds to step S106.

[0028] At step S106, the controller 30 cranks the power machine 40 of Fig. 1 starts it and then begins supplying fuel to the power unit 40. The controller 30 executes step S108 as soon as the power unit 40 is running at a sufficiently stable speed.

[0029] At step S108, the controller starts 30 of Fig. 1. To allow the generated electrical energy (arrow 11) to be supplied to the traction motor 12. Depending on the embodiment, this can occur directly or indirectly via the RESS 18 and / or the PIM 16. Once the traction motor 12 is supplied with power in this way, the process 100 continues to step S110.

[0030] At step S110, the controller 30 determines whether the vehicle is 10 out of Fig.1 was stopped. If this is the case, procedure 100 continues to step S112. Otherwise, procedure 100 repeats step S108.

[0031] In step S112, the controller 30 can execute any number of control actions depending on the status of the vehicle 10 when it is stationary. For example, if the vehicle 10 has been stopped, switched off, and connected to a charging socket, the controller 30 can automatically switch off the motor 40. In such an embodiment, the on / off status of the motor can be linked to the on / off position of the key. If the vehicle 10 has only been stopped at a traffic light, the controller 30 can continue generating electrical energy (arrow 11), directing any excess energy to the RESS 18 for storage.

[0032] Upon reading the preceding disclosure, the person skilled in the art will readily recognize several advantages of the construction disclosed herein. A significant advantage lies in the fact that angular momentum can be stored in a rotating mass, i.e., in one or both rings 20 and 22, in the manner of a flywheel. A mechanical coupling between a mechanical energy source and the ring can thus be used to store mechanical energy. For example, a regenerative braking event conventionally requires an oversized battery stack to absorb the regenerative high-current charging pulses. A battery stack can be dimensioned with greater attention to cost reduction if the high-current charging pulses can be used to power the rotation of the rings 20 and / or 22, thereby storing the energy from the regenerative event on the respective rings.The ring(s) of the APU 50 are stored for slower feedback to the RESS 18.

[0033] The same applies to any other event where mechanical energy can be converted back into electrical energy and supplied directly back to the PIM 16 or the traction motor 12, so that the APU 50 is treated like an electrical energy storage device. Another significant advantage is the possibility of designing the shape of the rings 20, 22 to act like a cage-like fan, which can be used to help cool the APU 50, possibly entirely if such a design uses an external combustion engine or a very efficient internal combustion engine.

[0034] Although the best ways of carrying out the invention have been described in detail, experts in the field to which this invention relates will recognize various alternative designs and embodiments for putting the invention into practice within the scope of the attached claims.

Claims

[1] Electric vehicle (10) comprising: a gearbox (14) with an input element (140); an electric traction motor (12) with a motor output shaft (15) which is mechanically coupled to the input element (140); a rechargeable energy storage system (RESS) (18) which is electrically connected to the electric traction motor (12); an auxiliary power unit (APU) (50) with: a set of induction coils; an outer ring (22); an inner ring (20) which is coaxial to the outer ring (22) and is positioned radially inside the same, wherein the outer ring (22) and / or the inner ring (20) is / are rotatable with respect to the other in order to generate an electric current in the set of induction windings; a gear element (26) in a driving connection with the outer ring (22) or inner ring (20) which rotates; a power machine (40) arranged radially within the inner ring (20) and containing a power extraction mechanism (24) mechanically coupled to the transmission element (26); and a controller (30) in electrical connection with the APU (50) and the RESS (18); wherein the controller (30) can be operated to detect when a level of energy available in the RESS (18) falls below a calibrated threshold, and to selectively excite the APU (50) to generate electrical power via the rotation of the outer ring (22) and / or the inner ring (20) whenever the energy available in the RESS (18) falls below the calibrated threshold; wherein, in the event of a regenerative braking event or any other event in which mechanical energy can be converted into electrical energy, an angular momentum can be stored in one or both rings (20, 22) for a slower return of electrical energy to the rechargeable energy storage system (18). [2] Electric vehicle (10) according to claim 1, wherein the power extraction mechanism (24) has a rotation axis (80) which is coaxial to a rotation axis of the inner ring (20). [3] Electric vehicle (10) according to claim 1, wherein: either the outer ring (22) or the inner ring (20) is attached; the induction windings are connected to the ring (20, 22) which is attached, or are designed as this ring; and the rotating ring (20, 22) contains a plurality of permanent magnets (58) oriented towards the induction windings. [4] Electric vehicle (10) according to claim 1, further comprising a chain or drive belt (60) which connects the power extraction mechanism (24) directly to the transmission element (26). [5] Electric vehicle (10) according to claim 1, wherein the electric vehicle (10) includes a body (27) defining a compartment (25) and wherein the APU (50) is positioned entirely within the compartment (25). [6] Electric vehicle (10) according to claim 5, wherein the compartment (25) is a spare wheel container which at least partially defines a channel (28) from the power unit (40) to the environment. [7] Electric vehicle (10) according to claim 1, wherein the engine (40) is a piston-driven heat engine with a plurality of cylinders (35). [8] Electric vehicle (10) according to claim 7, wherein the cylinders (35) are arranged in a circular configuration such that the longitudinal axis (110, 210) of each cylinder (35) intersects the axis of rotation (80) of the outer (22) and inner (20) ring. [9] Electric vehicle (10) according to claim 1, wherein the power engine (40) is a Wankel power engine.

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