Drive device for a motor vehicle and method for operating a drive device

Abstract

A drive device for a motor vehicle. A first drive assembly, a second drive assembly, and an epicyclic gear train, via which the first drive assembly and the second drive assembly can be coupled to each other and to a driven shaft of the drive device. The first drive assembly is coupled to a first transmission element, the second drive assembly is coupled to a second transmission element, and the driven shaft is coupled to a third transmission element of the epicyclic gear train. The epicyclic gear train has a locking clutch for coupling of the second transmission element and the third transmission element to each other and the first transmission element can be braked by means of a braking device.

Claims

1. A drive device for a motor vehicle, comprising: a first drive assembly, which is an internal combustion engine, a second drive assembly, which is an electric motor, a first epicyclic gear train having a first transmission element, a second transmission element, and a third transmission element, and a driven shaft of the drive device, wherein the first drive assembly is coupled to the first transmission element, the second drive assembly is coupled to the second transmission element, and the driven shaft is coupled to the third transmission element via a change gear transmission having a single input from the first epicyclic gear train and a single output at the driven shaft, wherein the first transmission element is configured to be braked by a braking device, wherein the first epicyclic gear train has a locking clutch for coupling of the second transmission element and the third transmission element to each other, and wherein the braking device has a freewheel that permits a rotational movement of the first transmission element in a first direction of rotation and prevents it in a second direction of rotation that is opposite to the first direction of rotation.

2. The drive device according to claim 1, wherein the freewheel is directly coupled to the first transmission element or is coupled to it via a shift clutch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in detail below on the basis of the exemplary embodiments illustrated in the drawing, without any limitation of the invention thereby occurring.

(2) FIG. 1 shows a schematic illustration of a drive device for a motor vehicle.

(3) FIG. 2A shows a schematic illustration of a drive device for a motor vehicle.

(4) FIG. 2B shows a schematic illustration of a drive device for a motor vehicle.

(5) FIG. 2C shows a schematic illustration of a drive device for a motor vehicle.

(6) FIG. 2D shows a schematic illustration of a drive device for a motor vehicle.

DETAILED DESCRIPTION

(7) FIG. 1 shows a schematic illustration of a drive device 1 for a motor vehicle, which is not illustrated here in more detail. The drive device 1 serves for driving a wheel axle 2 of the motor vehicle, which has two subaxles 3 and 4, which are operatively connected via a transmission 5, in particular an axle differential transmission, to a driven shaft 6 of the drive device 1. Each of the subaxles 3 and 4 is preferably associated with at least one wheel of the motor vehicle, which is not illustrated here, or is connected to it rigidly and/or permanently.

(8) The drive device 1 has a first drive assembly 7 and a second drive assembly 8. The two drive assemblies 7 and 8 can be optionally coupled to each other via an epicyclic gear train 9. The epicyclic gear train 9 has a first transmission element 10, a second transmission element 11, and a third transmission element 12. Mounted rotatably at the third transmission element 12, which in this regard is designed as a planet gear cage, is at least one planet gear 13.

(9) The first transmission element 10 and the second transmission element 11 are in operative connection to each other via the planet gear 13. For this purpose, preferably teeth of the planet gear 13 mesh with teeth of the first transmission element 10 and teeth of the second transmission element 11. In the exemplary embodiment illustrated here, the first transmission element 10 is designed as a sun gear and the second transmission element 11 is designed as a ring gear. It is also possible, however, to provide a reversed configuration.

(10) The first drive assembly 7 can be coupled to the first transmission element 10, whereas the second drive assembly 8 is coupled to the second transmission element 11, in particular rigidly and/or permanently. Provided between the first drive assembly 7 and the first transmission element 10 is a shift clutch 14, wherein, in a first shifting position of the shift clutch 14, the first drive assembly 7 is decoupled from the first transmission element 10 and, in a second shifting position, is coupled to it, preferably likewise rigidly and/or permanently. A vibration damping device 15, which is designed as a dual mass flywheel, for example, can be associated with the first drive assembly 7.

(11) The third transmission element 12 of the epicyclic gear train 9 is coupled to the driven shaft 6 via a change gear transmission 16. The driven shaft 6 is hereby present in the form of an output shaft of the change gear transmission 16 or is formed from it at least in regions. The change gear transmission 16 makes it possible to adjust at least two different gear ratios between the third transmission element 12 and the driven shaft 6.

(12) The epicyclic gear train 9 has a locking clutch 17, by means of which the second transmission element 11 and the third transmission element 12 can be coupled to each other. In a first shifting position of the locking clutch 17, the first transmission element 11 and the second transmission element 12 are decoupled from each other or are operatively connected solely via the planet gear 13. In a second shifting position, in contrast, the transmission elements 11 and 12 are locked with respect to each other, in particular rigidly or in a rotationally resistant manner. When the locking clutch 17 is closed, it is also possible to drive the driven shaft 6 without anything further, when the shift clutch 14 is opened, solely by means of the second drive assembly 8 via the epicyclic gear train 9, but usually only with low torque.

(13) In order to make driving possible also with a higher torque and/or when the shift clutch 14 is opened, a braking device 18 is provided, which is designed for braking the first transmission element 10, in particular for locking or blocking the first transmission element 10. The braking device 18 can comprise, for example, the shift clutch 14. If this is the case, then the first transmission element 10 can be braked by means of the first drive assembly 7, which is operated correspondingly.

(14) However, the torque that can thereby be transmitted to the driven shaft 6 via the epicyclic gear train 9 depends on the first drive assembly 7, in particular on its drag torque. For this reason, it is preferably provided that the braking device 18 has a freewheel 19, a freewheel 20, a brake 21, and/or a locking device 22. Basically, one of these devices is sufficient, so that the braking device 18 thus has the freewheel 19 or the freewheel 20 or the brake 21 or the locking device 22. Obviously, it is also possible to provide a plurality of these devices or all of these devices. For example, one of the freewheels 19 or 20 is provided in combination with the brake 21 or the locking device 22.

(15) The freewheel 19 permits a rotational movement of a drive shaft 23 of the first drive assembly 7 in a first direction of rotation and prevents it in a second direction of rotation that is opposite to the first direction of rotation. In contrast, the freewheel 20 permits a rotational movement of the first transmission element 10 in a first direction of rotation and prevents it in a second direction of rotation that is opposite to the first direction of rotation. By means of the freewheel 19, it is possible in this regard to brake or lock the first transmission element 10 only when the shift clutch 14 is closed, namely, in the second direction of rotation. In contrast, the freewheel 20 locks the first transmission element 10 in the second direction of rotation, regardless of the shifting position of the shift clutch 14.

(16) The brake 21 makes it possible preferably to adjust a specific braking force or a specific braking torque that is imposed on the first transmission element 10. Preferably, it operates in a force-fit manner. In contrast, the locking device 22 preferably serves for form-fit locking of the first transmission element 10. By use of the braking device 18, the driven shaft 6 can also be driven solely by means of the second drive assembly 8 when the locking clutch 17 is opened, because the torque thereby acting on the first transmission element 10 is supported against the braking device 18. This means that, by use of the epicyclic gear train 9, a plurality of gear ratios can be adjusted between the second drive assembly 8 and the driven shaft 6 or the number of gear ratios that can be adjusted by means of the change gear transmission 16 can be doubled.

(17) Additionally, the drive device 1 can have another drive assembly 24. Said drive assembly can be coupled by means of another shift clutch 25 to the first drive assembly 7. This is indicated by the arrow 26. The drive assembly 24 is coupled to or can be coupled to the driven shaft 6 via another epicyclic gear train 27. This is indicated by the arrows 28. Furthermore, the additional drive assembly 24 is coupled to or can be coupled to a secondary drive shaft 29 of a secondary drive 30 of the drive device 1.

(18) The additional epicyclic gear train 27 has a first transmission element 31, a second transmission element 32, and a third transmission element 33. Mounted rotatably at the third transmission element 33 is at least one planet gear 34, via which the first transmission element 31 and the second transmission element 32 are coupled to each other. For this purpose, teeth of the planet gear 34 mesh both with teeth of the first transmission element 31 and with teeth of the second transmission element 32. The first transmission element 31 is present in this case in the form of a ring gear, the second transmission element 32 is present in the form of a sun gear, and the third transmission element 33 is present in the form of a planet gear cage.

(19) The first transmission element 31 is preferably coupled rigidly to the additional drive assembly 24. The second transmission element 32 is coupled to the secondary drive shaft 29, preferably rigidly and/or permanently. The third transmission element 33 is coupled to the driven shaft 6, in particular rigidly and/or permanently, or can be coupled to it. It is possible for a locking clutch 35 to be associated with the additional epicyclic gear train 27, by means of which the second transmission element 32 and the third transmission element 33 can be locked with respect to each other. In a first shifting position of the locking clutch 35, the second transmission element 32 and the third transmission element 33 are consequently decoupled from each other and, in a second shifting position, they are coupled to each other, preferably rigidly.

(20) More preferably, it is provided that, by means of the additional drive assembly 24, it is possible to regulate the speed of the secondary drive shaft 29. For this purpose, the additional drive assembly 24 is preferably decoupled from the first drive assembly 7 or the additional shift clutch 25 is opened, in particular completely opened. Additionally, the locking clutch 35 is opened, so that the transmission elements 32 and 33 are released with respect to each other, that is, not coupled to each other. For example, it is then provided that the secondary drive shaft 29 is coupled to the driven shaft 6 and accordinglyin the case that the motor vehicle is in motionis driven using the kinetic energy of the motor vehicle. Obviously, however, the described procedure can also find use when the motor vehicle is at a standstill.

(21) When the locking clutch 35 is opened, the speed of the secondary drive shaft 29 is adjusted depending on the speed of the driven shaft 6 and the speed of the additional drive assembly 24. Accordingly, it is provided that the speed of the additional drive assembly 24 is chosen and adjusted in such a way that the speed of the secondary drive shaft 29 corresponds to a target speed, regardless of the speed of the driven shaft 6. As a result of this, for example, the speed of the secondary drive shaft 29 can be kept constant or adjusted and, in particular, regulated to the target speed by means of the additional drive assembly 24, in particular also when the speed of the driven shaft 6 is changed.

(22) When the driven shaft 6 is at a standstill, the entire power applied to the secondary drive shaft 29 is then supplied by means of the additional drive assembly 24. The higher the speed of the driven shaft 6, the higher is then the fraction of the power supplied by the driven shaft 6 and applied to the secondary drive shaft 29given a constant speed of the secondary drive shaft 29. Conversely, the fraction supplied by the additional drive assembly 24 is, of course, smaller.

(23) Additionally or alternatively, it can be provided that the driven shaft 6 is coupled to the first drive assembly 7 via the additional epicyclic gear train 27, in particular in a rotationally resistant manner. For this purpose, for example, the shift clutch 25 and the locking clutch 35 are closed, in particular completely closed. The shift clutch 14 is preferably opened in this case, even though the coupling of the driven shaft 6 to the first drive assembly 7 can be made via the additional epicyclic gear train 27, even when the shift clutch 14 is closed. The procedure can be provided independently from the braking of the first transmission element 10 by means of the braking device 18, in particular regardless of the presence of one freewheel or a plurality of freewheels 19 and 20.

(24) In this way, it is possible, for example, to supply a thrust torque of the first drive assembly 7 at the driven shaft 6, in particular for braking of the driven shaft 6 and consequently of the motor vehicle. For example, this procedure can find application when the second drive assembly 8 cannot be operated for recuperation, in particular due to a full energy storage system. The energy storage system normally serves for intermediate storage of the electrical energy supplied by the second drive assembly 8 in recuperative mode. However, if the energy storage system is completely full or has a state of charge that is greater than a maximum state of charge, then the first drive assembly 7 is intended to be employed in the described way for braking of the driven shaft 6.

(25) An embodiment of the drive device 1 or of the secondary drive 30 in the way described makes possible an extremely flexible and energy-efficient operation of the drive device 1. In addition, through the provision of the braking device 18, it is possible to create a relatively large number of gear ratios between the second drive assembly 8 and the driven shaft 6, even when the driven shaft 6 is driven via the epicyclic gear train 9 solely by means of the second drive assembly 8.

(26) However, the embodiment with the secondary drive 30 illustrated here also makes possible an operation of the drive device 1, in which the driven shaft 6 is driven by means of the second drive assembly 8 via the epicyclic gear train 9 when the shift clutch 14 is opened, wherein, through appropriate adjustment of the locking clutch 17, one of a plurality of gear ratios is adjusted between the second drive assembly 8 and the driven shaft 6.

(27) In addition, it can be provided that the driven shaft 6 is driven by means of the first drive assembly 7, namely, via the additional epicyclic gear train 27. For this purpose, the shift clutch 14 is opened and the additional shift clutch 25 is closed. Through appropriate adjustment of the locking clutch 35, it is also possible in this case to adjust one of a plurality of gear ratios between the first drive assembly 7 and the driven shaft 6.

(28) Turning now briefly to FIGS. 2A, 2B, 2C, and 2D, these Figures show exemplary variations of the drive device 1, as discussed previously. In particular, FIG. 2A shows an exemplary embodiment in which the freewheel 20 is coupled directly to the first transmission element 16, FIG. 2B shows an exemplary embodiment in which the brake 21 is coupled directly to the first transmission element 16, FIG. 2C shows an exemplary embodiment in which the brake 21 is coupled to the first transmission element 16 via the shift clutch 14, and FIG. 2D shows an exemplary embodiment in which the locking device 22 is coupled to the first transmission element 16 via the shift clutch 14.