Drive system for a vehicle that includes a maneuvering pedal

Abstract

Drive system for a vehicle, wherein the drive system comprises an output shaft (2a) of an internal combustion engine (2), an electric machine (9) with a stator (9a) and a rotor (9b) and a planetary gear system comprising three components in the form of a sun gear (10), a ring gear (11) and a planet carrier (12), wherein the output shaft (2a) of the internal combustion engine (2) is connected to a first of the components of the planetary gear such that a rotation of this shaft leads to a rotation of this component, wherein an output shaft (3a) of the planetary gear for transmitting a torque for propulsion of the vehicle is connected to a second component of the planetary gear such that a rotation of this shaft results in a rotation of this component, and wherein the rotor (9b) of the electric machine is connected to a third of the aforementioned components of the planetary gear, such that a rotation of the rotor (9b) results in a rotation of this component, wherein the drive system further comprises an arrangement (20, 30) for exchanging electrical energy with the electric machine (9), a control unit (18) configured to control the fuel supply to the internal combustion engine (2) and the exchange of electrical energy of the electric machine (9) with the arrangement (20, 30), and an accelerator pedal (22) controlled by a driver of the vehicle to control the fuel supply to the internal combustion engine (2) and thereby the speed of the output shaft (2a) of the internal combustion engine (2), characterized in that the drive system comprises a further pedal (23) controllable by the driver to request a torque to be applied to the output shaft (3a) of the planetary gear for the propulsion of the vehicle depending on the position of the further pedal, and means (24) for sending information about the position of the further pedal to a control unit (18), wherein the control unit (18) is configured to control the electric machine (9) to obtain the requested torque at the output shaft (3a) of the planetary gear.

Description

TECHNICAL AREA OF INVENTION

[0001] The present invention relates to a drive system for a vehicle according to the preamble of attached claim 1.

[0002] The invention relates in particular, but not exclusively, to such a drive system for motor vehicles in the form of motorized and wheeled commercial vehicles, especially heavy vehicles such as trucks and buses.

[0003] The invention thus relates to a drive system for propelling a hybrid vehicle, which is generally a vehicle that can be driven by a primary motor, here an internal combustion engine, and a secondary motor, here an electric machine. For this purpose, the vehicle is equipped with said arrangement for exchanging electrical energy with said electric machine, and this arrangement can, for example, include suitable means for storing energy, such as electric batteries or a capacitor for storing electrical energy, but instead or additionally, for example, include another electric machine. By exchanging electrical energy with said arrangement, the electric machine can alternatively operate as a motor and generator, depending on the operating state of the vehicle.When the vehicle brakes, the electric machine generates electrical energy that can be stored, and the stored electrical energy can later be used, for example, to power the vehicle.

[0004] The output shaft of the planetary gear set in a drive system, as described in the introduction, can form the input shaft of a gearbox within the drive system. By connecting the output shaft of the internal combustion engine, the rotor of the electric motor, and the input shaft of the gearbox in such a drive system using a planetary gear set, a conventional clutch mechanism and several of its disadvantages can be avoided. Using a conventional clutch mechanism to disengage the gearbox input shaft from the internal combustion engine during gear changes has drawbacks, such as heating of the clutch mechanism's discs, leading to increased fuel consumption and wear of the clutch discs. Significant fuel losses occur, particularly when starting the vehicle. Other disadvantages of a conventional clutch mechanism include its weight and cost.It is also relatively space-consuming. Furthermore, friction losses occur when a hydraulic converter / torque converter, commonly used in automatic transmissions, is employed. STATE OF THE ART

[0005] A drive system of the type defined above is known, for example, from EP 1 319 546 A1 and SE 1 051 384 A1. Although the drive system disclosed in SE 1 051 384 A1 in particular functions well and has a number of advantageous features, there is a continuous effort to improve such a drive system with regard to its behavior and function in certain situations. Further drive systems are known from documents DE 11 2014 005 375 T5, US 2008 / 0 269 011 A1 and DE 11 2013 004 870 B4. BRIEF SUMMARY OF THE INVENTION

[0006] The object of the present invention is to provide a drive system of the type defined in the introduction which is improved in at least some aspects with respect to such already known drive systems.

[0007] This problem is solved according to the invention by providing such a drive system with the features listed in the characterizing section of the appended claim 1.

[0008] A vehicle drive system with such an additional pedal can be considered to have a clutch pedal, so that the drive system has three pedals like a conventional drive system with a clutch mechanism but without a clutch function. The operation of said additional pedal will be the same as that of a clutch-by-wire (CBW) system, but with a completely different function. US 2010 / 0298094A1 discloses such a clutch-by-wire in a motor vehicle with a drive system of a different type than that defined in the introduction, where it serves as the actual operating mechanism for a clutch during gear changes. The said additional pedal in the drive system according to the present invention, which is based on the control-by-wire principle, provides the driver of the vehicle with the ability to control the torque applied to the output shaft of the planetary gear set to propel the vehicle.This feature will be useful in challenging situations where the vehicle's normal control of the combustion engine and electric motor by the vehicle's control unit results in insufficient torque being applied to the planetary gear's output shaft. This can lead to a risk of the vehicle getting stuck, for example, when driving on poor-quality roads, dirty surfaces, and / or snow and ice. The vehicle's maneuvering behavior during loading and unloading can also be improved by controlling the torque of the electric motor via an additional pedal. The position of this pedal will then send information, such as an electrical signal, to the control unit that manages the electric motor, ensuring the appropriate torque is applied to the planetary gear's output shaft.This control unit function may be included in the control unit configured to control the fuel supply to the internal combustion engine and to exchange electrical energy of the electric machine with the said arrangement when it is not acting on the said further pedal or is provided by a separate control unit.

[0009] According to one embodiment of the invention, the drive system includes means for switching the drive system into a shunting mode, in which a neutral position of the said additional pedal corresponds to a requested zero torque to be applied to the said output shaft of the planetary gear, and the value of the requested torque increases, but with opposite signs, when the said additional pedal is moved in opposite directions from the said neutral position, in order to enable the vehicle to be driven forwards and backwards by controlling the said additional pedal. Switching the drive system into such a mode when shunting the vehicle will improve and facilitate the control of the drive system by the said additional pedal during shunting, such as when loading and unloading a truck.

[0010] According to another embodiment of the invention, the control unit for controlling the electric machine is configured to treat the requested torque as zero torque when the accelerator pedal is within a certain distance from its assumed position when not operated by a driver, such as less than 40% or less than 20% of its possible range of motion from that position. This ensures that no unsolicited torque is applied to the output shaft of the planetary gear for propelling the vehicle when the driver removes their feet from the pedals. However, when the accelerator pedal is moved beyond this specified distance, it can function normally to control the supply of fuel to the internal combustion engine.

[0011] According to another embodiment of the invention, the accelerator pedal is configured in maneuvering mode so as not to affect the control of the internal combustion engine or the requested torque when moved by the driver. This means that the accelerator pedal does not control either the speed of the internal combustion engine's output shaft or the torque applied to the planetary gear for propelling the vehicle; rather, control is achieved solely by moving the other pedal.

[0012] According to another embodiment of the invention, the drive system comprises means that are controllable for disconnecting and connecting said additional pedal with respect to its influence on the operation of the drive system. This means that, if desired, the vehicle can be operated in two-pedal mode by interrupting said additional pedal.

[0013] According to another embodiment of the invention, the planetary gear carrier is said to be the second component, and according to a further embodiment, the sun gear of the planetary gear is said to be the first component and the ring gear the said to be the third component. A compact structure that can be easily installed in spaces already available for drive trains with clutch mechanisms instead of planetary gears can be obtained by connecting the rotor of the electric machine to the ring gear and the output shaft of the internal combustion engine to the sun gear. A transmission for a hybrid vehicle can thus be made compact and not significantly more space-consuming than a standard transmission.

[0014] This means that the weight increase normally caused by a hybrid design can be considerably reduced. Another advantage is that connecting the electric machine's rotor to the ring gear results in a higher possible braking torque than if it were connected to the sun gear instead.

[0015] According to another embodiment of the invention, the drive system comprises a first locking device that separates a locking position in which two of said components are locked, so that the three components rotate at the same number of revolutions, from a release position in which the components are allowed to rotate at different numbers of revolutions.

[0016] According to another embodiment of the invention, the drive system comprises a second locking device that separates a locking position, in which the output shaft of the internal combustion engine is locked to said first component, from a release position, in which the output shaft of the combustion engine is released from said first component and can rotate independently. The presence of such a second locking device leads to a number of advantages, such as the ability to start the internal combustion engine when torque is transmitted from the output shaft of the planetary gear to drive the vehicle.

[0017] According to another embodiment of the invention, the said output shaft of the planetary gear forms an input shaft of a transmission of the vehicle.

[0018] According to another embodiment of the invention, the arrangement for exchanging electrical energy with the electric machine comprises an additional electric machine with a stator and a rotor, which is connected to the output shaft of the internal combustion engine between the internal combustion engine and the first component. The arrangement of such an additional electric machine makes it possible to achieve an exchange of electrical energy with the electric machine that interacts with the third component of the planetary gear without requiring any means of storing electrical energy, such as electric batteries, in the arrangement. For example, it will be possible to drive a stationary vehicle while maintaining power balance.while means for storing any available electrical energy, such as electric batteries and other electrical loads of the vehicle, are provided simultaneously with a controlled current / controlled power while maintaining a desired torque in the vehicle's drivetrain.

[0019] According to a further embodiment of the invention, the arrangement for exchanging electrical energy with said electrical machine comprises a device for storing electrical energy, such as at least one electrical battery.

[0020] The present invention also relates to a motor vehicle, in particular a vehicle equipped with wheels, such as a truck or a bus, which comprises a drive system according to the invention.

[0021] Further advantages and advantageous features of the present invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] With reference to the accompanying drawings, a specific description of embodiments of the invention, which are given as examples, follows below.

[0023] In the drawings: Fig. Figure 1 schematically represents a drive train of a vehicle which may be equipped with a drive system according to the invention. Fig. Figure 2 is a more detailed, but still simplified, view of a section of the drive system. Fig. Figure 3 is a simplified view showing the general structure of a drive system according to a first embodiment of the invention, and Fig. Figure 4 is a simplified view showing the general structure of a drive system according to a second embodiment of the invention. DETAILED DESCRIPTION OF EXECUTIONS OF THE INVENTION

[0024] Fig. Figure 1 shows a drive train for a heavy vehicle 1. The drive train comprises an internal combustion engine 2, a transmission 3, and a number of drive shafts 4 and drive wheels 5. The drive train has an intermediate section 6 located between the internal combustion engine 2 and the transmission 3.

[0025] Fig. Figure 2 shows a section of the components in the aforementioned intermediate section 6 in more detail, namely those that are also present in previously known drive systems of the type defined in the introduction, such as SE 1051384-4. The internal combustion engine 2 is provided with an output shaft 2a and the transmission 3 with an input shaft 3a in the intermediate section 6. The output shaft 2a of the internal combustion engine is arranged coaxially with the input shaft 3a of the transmission. The output shaft 2a of the internal combustion engine and the input shaft 3a of the transmission rotate together about an axis of rotation 7. The intermediate section 6 comprises a housing 8, which encloses an electric machine 9 and a planetary gear set. The electric machine 9 comprises a stator 9a and a rotor 9b. The stator 9a comprises a stator core, which is attached to the inner wall of the housing 8. The stator core comprises the stator windings.The first electric machine 9 is configured to use stored electrical energy under certain operating conditions to supply a driving force to the input shaft 3a of the gearbox, and during other operating conditions to use kinetic energy of the input shaft 3a of the gearbox to generate and store electrical energy.

[0026] The planetary gear set is arranged essentially radially within the stator 9a and the rotor 9b of the electric machine. The planetary gear set comprises a sun gear 10, a ring gear 11, and a planet carrier 12. The planet carrier 12 carries a number of planet gears 13, which are arranged to rotate in a radial space between the sun gear 10 and the teeth of the ring gear 11. The sun gear 10 is attached to a circumferential surface of the output shaft 2a of the internal combustion engine. The sun gear 10 and the output shaft 2a of the internal combustion engine rotate as a unit for a first number of revolutions n1. The planet carrier 12 includes a locking section 12a, which is attached to a circumferential surface of the input shaft 3a of the gearbox by means of a splined connection 14. The planet carrier 12 and the input shaft 3a of the gearbox can rotate as a unit for a second number of revolutions by means of this splined connection.

[0027] The ring gear 11 has an outer circumferential surface to which the rotor 9b is attached. The rotor 9b and the ring gear 11 form a rotatable unit that rotates at a third revolution n3.

[0028] The drive system further comprises a first locking device in that the output shaft 2a of the internal combustion engine is provided with a displaceable coupling element 15. The coupling element 15 is attached to the output shaft 2a of the internal combustion engine by means of a splined connection 16. The coupling element 15 is mounted on the output shaft 2a of the internal combustion engine in a rotationally secure manner and is axially displaceable on this output shaft 2a. The coupling element 15 comprises a coupling section 15a, which is connected to a coupling section 12b of the planetary gear carrier 12.A schematically shown displacement element 17 is arranged to displace the coupling element 15 between a first position, in which the coupling sections 15a, 12b are not in mutual engagement corresponding to a release position of the first locking means, and a second position, in which the coupling sections 15a, 12b are in mutual engagement corresponding to a locking position of the first locking device. In this locking position, the output shaft 2a of the internal combustion engine and the input shaft 3a of the transmission are locked, and they, and consequently the rotor of the electric machine, will rotate at the same number of revolutions. This state can be described as a locked planetary gear. The locking mechanism can also have a different design, such as that disclosed in Swedish patent application 1250696-0.The locking device can also be formed by a suitable type of friction coupling or clutch.

[0029] An electrical control unit 18 is configured to control the displacement element 17. The control unit 18 is also configured to determine when the electric machine should operate as a motor and when it should operate as a generator. The control unit 18 can receive information about suitable operating parameters to determine which function to select. The control unit 18 can be a computer with software for this task. The control unit 18 controls a schematically indicated control device 19, which regulates the flow of electrical energy between a hybrid battery 20 and the stator windings 9a of the electric machine. When the electric machine 9 operates as a motor, electrical energy stored in the hybrid battery 20 is supplied to the stator 9a.When the electric machine operates as a generator, electrical energy is supplied from the stator 9a to the hybrid battery 20. The hybrid battery 20 supplies and stores electrical energy at a voltage on the order of 300–900 V. It is important that the electric machine 9 and the planetary gear unit form a compact unit, as the intermediate section 6 between the internal combustion engine 2 and the transmission 3 in a vehicle is limited. The components 10, 11, 12 of the planetary gear unit are arranged essentially radially within the stator 9a of the electric machine. The rotor 9b of the electric machine, the ring gear 11 of the planetary gear unit, the output shaft 2a of the internal combustion engine, and the input shaft 3a of the transmission are arranged to rotate together about a common axis 7. This design means that the electric machine 9 and the planetary gear unit require comparatively little space.Vehicle 1 is equipped with an engine control function 21, which controls the rotational speed n1 of the internal combustion engine 2. The control unit 18 can thus activate the engine control function 21 and generate a zero-torque state in the transmission 3 during gear changes. The drive system can, of course, be controlled by several different control units instead of a single control unit 18.

[0030] The drive system is also equipped with an accelerator pedal 22, which is controlled by the driver through a connection with the engine control function 21. The section of a drive system according to the present one described so far and in Fig. The invention shown in section 2 is also present in a drive system according to SE 1051384-4. The drive system disclosed therein has a two-pedal design, in that it also includes a brake pedal (not shown). The section of a drive system according to a first embodiment of the invention, which has been added to the section described so far, is now referred to in Section 2. Fig. 3 described.

[0031] The in Fig. The drive system shown in section 3 differs from the one in Fig. As shown in Figure 2, no transmission is provided downstream of the output shaft 3a of the planetary gear unit to transmit torque from the planetary gear unit for propelling the vehicle. This drive system includes, in addition to the accelerator pedal 22, a further pedal 23 which can be controlled by the driver of the vehicle to request torque that is applied to the output shaft 3a of the planetary gear unit for propelling the vehicle, depending on the position of this further pedal. The device 24 is configured to send information about the position of this further pedal 23 to a control unit 18, which is configured to control the electric motor 9 to obtain the requested torque at the output shaft of the planetary gear unit.This allows the driver to choose to control the speed of the internal combustion engine by acting on the accelerator pedal 22, and to control the torque supplied by the electric motor by acting on the other pedal 23. During normal driving, such as at a constant speed, the driver will only actuate the accelerator pedal to control the torque exerted on the output shaft 3a of the planetary gear by the internal combustion engine 2 and the electric motor 9. However, in some special situations, such as driving on poor road conditions, on snow and ice, or when maneuvering during loading and unloading, the driver might wish to actively control the torque applied to said output shaft 3a of the planetary gear, and this can then be done by acting on the other pedal 23.

[0032] The drive system further includes means 25 for switching the drive system into a shunting mode, in which a neutral position of the additional pedal 23 corresponds to a requested zero torque to be applied to the output shaft 3a of the planetary gear. The value of the requested torque increases, but with opposite signs, when the additional pedal 23 is moved in opposite directions from the neutral position, in order to enable the vehicle to be driven forwards and backwards by controlling the additional pedal 23. Accordingly, the accelerator pedal 22 is not involved in the vehicle's driving operation when the drive system is switched into shunting mode by actuating said device 25. However, it would also be possible to allow the accelerator pedal to participate in driving the vehicle even in shunting mode.The drive system also includes device 26, which is controllable for disconnecting and connecting the further pedal 23 with respect to the influence of a control thereof on the actuation of the drive system, so that the drive system can be switched between a three-pedal version and a two-pedal version.

[0033] A drive system according to a second embodiment of the invention is in Fig. 4 shown. This drive system differs, among other things, from the one in Fig. 3 shown by the fact that it has a gearbox 3 and no means for storing electrical energy, but that the arrangement for exchanging electrical energy with the electric machine 9 instead comprises a second electric machine 30, which makes it possible to omit means for storing electrical energy if desired. The second electric machine has a stator 31 with stator windings and a rotor 32, which is connected to the output shaft 2a of the internal combustion engine. A second locking device 33, which has a similar construction to the first, in Fig. The locking device 34, shown in more detail in Figure 2, is configured such that, in a release position, it releases a first section 35 of the output shaft of the internal combustion engine, which is closest to the internal combustion engine, from a second section 36, which is connected to the sun gear 10 of the planetary gear set, so that the rotor 32 of the second electric machine and the sun gear 10 can rotate independently of the first section 35 of the output shaft of the internal combustion engine. The second locking device can be moved into a locking position in which both sections 35 and 36 of the output shaft of the internal combustion engine are locked to each other, thereby locking the first section 35 to the rotor of the second electric machine.The control unit 18 is configured to control the supply of fuel to the internal combustion engine 2 and the exchange of electrical energy between the first electric machine 9 and the second electric machine 30. This drive system has an additional pedal 23 with the same function as the one in the [reference missing]. Fig. 3 is present in the embodiment shown. Accordingly, the torque exerted on the input shaft 3a of the transmission 3 can be controlled by adjusting the position of the additional pedal 23.

[0034] The invention is of course in no way limited to the embodiments described above, since many possibilities for modifications thereof are obvious to the person skilled in the art without deviating from the scope of the invention as defined in the attached claims.

[0035] It is pointed out that even in the case of a drive system with two electric machines, the in Fig. The 4 types shown are means for storing electrical energy, such as electric batteries, which are usually present.

Claims

[1] Drive system for a vehicle, wherein the drive system comprises an output shaft (2a) of an internal combustion engine (2), an electric machine (9) with a stator (9a) and a rotor (9b) and a planetary gear system comprising three components in the form of a sun gear (10), a ring gear (11) and a planet carrier (12), wherein the output shaft (2a) of the internal combustion engine (2) is connected to a first of the components of the planetary gear such that a rotation of this shaft leads to a rotation of this component, wherein an output shaft (3a) of the planetary gear for transmitting a torque for propulsion of the vehicle is connected to a second component of the planetary gear such that a rotation of this shaft results in a rotation of this component, and wherein the rotor (9b) of the electric machine is connected to a third of the aforementioned components of the planetary gear, such that a rotation of the rotor (9b) results in a rotation of this component, wherein the drive system further comprises an arrangement (20, 30) for exchanging electrical energy with the electric machine (9), a control unit (18) configured to control the fuel supply to the internal combustion engine (2) and the exchange of electrical energy of the electric machine (9) with the arrangement (20, 30), and an accelerator pedal (22) controlled by a driver of the vehicle to control the fuel supply to the internal combustion engine (2) and thereby the speed of the output shaft (2a) of the internal combustion engine (2), characterized by, that the drive system comprises a further pedal (23) controllable by the driver to request a torque to be applied to the output shaft (3a) of the planetary gear for the propulsion of the vehicle depending on the position of the further pedal, and means (24) for sending information about the position of the further pedal to a control unit (18), wherein the control unit (18) is configured to control the electric machine (9) to obtain the requested torque at the output shaft (3a) of the planetary gear. [2] Drive system according to claim 1, characterized by, that it includes means (25) to switch the drive system into a shunting mode in which a center position of the further pedal (23) corresponds to a requested zero torque to be applied to the output shaft (3a) of the planetary gear, the value of the requested torque increasing, but with opposite signs, when the further pedal is moved in opposite directions from the center position to enable the vehicle to be driven forwards and backwards by controlling the further pedal. [3] Drive system according to claim 1 or 2, characterized by, that the control unit (18) configured to control the electric machine (9) is configured to regard the requested torque as zero torque when the accelerator pedal (22) is within a certain distance from the position it is in when not operated by a driver, such as less than 40% or less than 20% of its possible range of motion from the latter position. [4] Drive system according to claim 2 or 2 and 3, characterized by , that the accelerator pedal (22) is in the maneuvering mode which is configured so that it has no effect on the control of the internal combustion engine (2) and the requested torque when moved by a driver. [5] Drive system according to any one of the preceding claims, characterized by, that it has means (26) which are controllable for disconnecting and connecting the further pedal (23) with respect to the influence of a control thereof on the operation of the drive system. [6] Drive system according to any one of the preceding claims, characterized by , that the planet carrier (12) is the second component. [7] Drive system according to claim 6, characterized by , that the sun gear (10) of the planetary gear is the first component and the ring gear (11) is the third component. [8] Drive system according to any one of the preceding claims, characterized by , that it comprises a first locking means (34) which is transferable between a locking position in which two of the components are locked so that the three components rotate at the same number of revolutions and a release position in which the components can rotate at different speeds. [9] Drive system according to any one of the preceding claims, characterized by , that it comprises a second locking means (33) which is transferable between a locking position in which the output shaft (2a) of the internal combustion engine (2) is locked to the first component (10) and a release position in which the output shaft of the internal combustion engine is released from the first component and can rotate independently. [10] Drive system according to any one of the preceding claims, characterized by , that the output shaft of the planetary gear forms an input shaft (3a) of a gearbox (3) of the vehicle. [11] Drive system according to any one of the preceding claims, characterized by, that the arrangement for exchanging electrical energy with the electric machine (9) includes an additional electric machine (30) with a stator (31) and a rotor (32) which is connected to the output shaft (2a) of the internal combustion engine (2) between the internal combustion engine and the first component (10). [12] Drive system according to any one of the preceding claims, characterized by , that the arrangement for exchanging electrical energy with the electrical machine includes a means (20) for storing electrical energy, such as at least one electrical battery. [13] Motor vehicle (1), in particular a vehicle equipped with wheels, such as a truck or a bus, characterized by that it comprises a drive system according to one of claims 1-12.

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