Hybrid drive system and vehicle

Abstract

Hybrid drive system (1) comprising an internal combustion engine (2) and an electric machine (3), and a transmission (4) comprising a first spur gear unit (B) and a second spur gear unit (A), which drive via at least one intermediate shaft (12), and a four-shaft planetary gear set (8), wherein a first shaft (8.1) is coupled or can be coupled to a crankshaft (5) of the internal combustion engine (2), wherein a rotor of the electric machine (3) is coupled, can be coupled to, or is configured as a second shaft (8.2), wherein a first input shaft (9) of the first spur gear unit (B) is rotationally fixed to a third shaft (8.3), and wherein a second input shaft (10) of the second spur gear unit (A) is rotationally fixed to a fourth shaft (8.4) of the planetary gear set (8), characterized in that the first and the second spur gear unit (B, A) each have exactly one spur gear pair (11, 14), and a locking switching element (SK) for locking two of the shafts (8.1, 8.2, 8.3, 8.4) of the planetary gear set (8) is arranged in an axial direction (a) along the input shafts (9, 10) between the two spur gear pairs (11, 14), wherein a brake switching element (BA) is provided for rotationally fixedly connecting the fourth shaft (8.4) of the planetary gear set (8) to a housing (17) of the transmission (4), wherein a second switching element (SA) and the brake switching element (BA) are arranged coaxially to the second input shaft (10) and in axial direction (a) on a side of the two spur gear pairs (11, 14) facing away from the planetary gear set (8), wherein the second switching element (SA) and the brake switching element (BA) are designed as a coupling switching element and can be switched with a single common sliding sleeve.

Description

[0001] The invention relates to a hybrid drive system with an internal combustion engine and an electric machine according to the type defined in the preamble of claim 1. The invention also relates to a vehicle with such a hybrid drive system.

[0002] Hybrid drive systems with an internal combustion engine, an electric motor, and a planetary gear are known, for example, from DE 10 2010 053 757 A1 and EP 3 261 233 A1. An electric drive system with an electric motor and a planetary gear is known from DE 10 2019 111 738 B3.

[0003] A generic hybrid drive system for a vehicle with an internal combustion engine and an electric motor is described, for example, in DE 10 2017 006 082 A1 or DE 10 2020 004 582 A1 by the applicant. A four-shaft planetary gear set is used, via which the electric motor and the internal combustion engine are coupled into the transmission of the hybrid drive system.

[0004] The design in the aforementioned state of the art is highly complex in the implementation of many functions and requires a lot of installation space, particularly in the axial direction, i.e. in the direction of the main transmission axis or the input shafts of the two spur gear sub-transmissions.

[0005] The object of the present invention is to provide a simple and, above all, very compact design in the axial direction with a large number of useful gear functions.

[0006] According to the invention, this object is achieved by a hybrid drive system having the features in claim 1, and here in particular in the characterizing part of claim 1.

[0007] Advantageous embodiments and further developments of the hybrid drive system according to the invention emerge from the dependent claims. Claim 7 also specifies a vehicle with such a hybrid drive system, which also achieves the object. An advantageous further development emerges from the dependent claim.

[0008] The hybrid drive system according to the invention serves in particular as a vehicle drive. It comprises an internal combustion engine and one or at least one electric machine, as well as a transmission with a first spur gear sub-transmission (B) and a second spur gear sub-transmission (A), which output via at least one countershaft (12), and with a planetary gear set with at least four shafts. In addition, two mechanical paths are provided via one spur gear sub-transmission and the other spur gear sub-transmission, which can be switchably connected to one another in order to deliver output energy either via one path, the other path, or both paths. A first shaft of the planetary gear set is coupled to a crankshaft of the internal combustion engine or can be coupled preferably via a separating clutch and optionally via a torsional vibration damper. A rotor of the electric machine is coupled or can be coupled to a second shaft of the planetary gear set.The rotor of the electric motor can also directly form this second shaft of the planetary gear set, for example, by the rotor of the electric motor forming the ring gear of the planetary gear set or being directly connected to it. A first input shaft of the first spur gear sub-gearbox and a second input shaft of the second spur gear sub-gearbox then form the third and fourth shafts of the planetary gear set, or are preferably connected to it in a rotationally fixed manner.

[0009] According to the invention, the first and second spur gear train each have exactly one spur gear pair in order to achieve a simple and compact design. The two spur gear pairs of the first spur gear train on the one hand and the second spur gear train on the other are arranged in such a way that, viewed in an axial direction along the two input shafts of the respective spur gear train, a blocking switching element for blocking two of the shafts of the planetary gear set is arranged between the two spur gear pairs. The planetary gear set therefore has a blocking switching element via which two of its shafts can be connected accordingly in order to block the planetary gear set so that it rotates as a block, i.e. without any relative movement of its components to one another.This interlocking shift element is arranged axially between the two spur gear pairs and thus axially between the two spur gear sub-transmissions. Furthermore, according to the invention, it is provided that the fourth shaft of the planetary gear set is connected in a rotationally fixed manner to a housing of the transmission via a brake shift element. When the interlocking shift element is open, an additional gear ratio is created via the first spur gear sub-transmission. This enables an extremely compact design in the axial direction with a very high gear ratio spread, i.e., very different gear ratios between the fastest and slowest gears. By using the four-shaft planetary gear set of the combustion engine and the electric machine in the described arrangement, a multitude of functions can nevertheless be implemented simply and efficiently with the hybrid drive system according to the invention.Furthermore, according to the invention, a second shifting element and the brake shifting element according to the invention are located coaxially with the second input shaft and axially on the side of the two spur gear pairs facing away from the planetary gear set. In the second spur gear pair, the idler gear of this second spur gear pair is thus arranged coaxially with the second input shaft. The fixed gear of this second spur gear pair is then arranged coaxially with the countershaft. The brake shifting element can then be used to brake the fourth shaft of the planetary gear set, which is non-rotatably connected to the second input shaft, relative to the housing.Furthermore, according to the invention, the second switching element and the brake switching element are designed as a coupling switching element and can be switched with a single common sliding sleeve, whereby on the one hand a structure that is as simple as possible and compact in the axial direction is realized and on the other hand the expenditure with regard to the components and the actuators is further reduced.

[0010] Axial, in the sense of the present invention, always means axial with respect to a main axis of rotation, which in turn coincides with the axes of rotation of the two coaxial input shafts. A rotationally fixed connection or coupling of two rotatably mounted elements is defined as meaning that these two elements are arranged coaxially to one another and are connected in such a way that they rotate at the same angular velocity.

[0011] The shafts of the planetary gear set correspond to its elements or are connected to them in a rotationally fixed manner. In an exemplary four-shaft planetary gear set, the elements are, for example, the ring gear, a first and a second sun gear, and the carrier or double carrier of the planetary gears meshing with the ring gear and the respective sun gear.

[0012] The interlocking shift element itself can, for example, be designed as a friction clutch, in order to enable interlocking of the elements even at different speeds of the corresponding shafts of the planetary gear set. According to a particularly favorable and advantageous embodiment, however, it can also be provided that the interlocking shift element is designed as a positive-locking clutch. Such a positive-locking clutch, which in particular dispenses with any type of synchronization elements, can be constructed particularly simply, cost-effectively, and compactly. It operates largely wear-free and, through the use of the electric motor, which is coupled or can be coupled to the second shaft of the four-shaft planetary gear set, allows the speeds to be adjusted as needed, in order to enable comfortable and reliable shifting even with the positive-locking clutch as the interlocking shift element.

[0013] According to an exceptionally advantageous development of the hybrid drive device according to the invention, it can also be provided that exactly one countershaft is provided with a non-rotatably connected output gear, wherein this output gear is arranged axially overlapping the planetary gear set. The single countershaft allows for a very compact transmission design transverse to the axial direction.

[0014] According to an advantageous embodiment of the hybrid drive system according to the invention, the internal combustion engine or its crankshaft can be connected to the first shaft of the planetary gear set via a separating clutch. A dual-mass flywheel for damping or eliminating torsional vibrations can be provided, either supplemented or compactly integrated with the separating clutch. Alternative designs of torsional vibration dampers are also conceivable. The separating clutch itself allows purely electric operation by separating the transmission or planetary gear set from the internal combustion engine, which correspondingly increases the possibilities for enhancing the functionality of the hybrid drive system according to the invention. The separating clutch itself can be designed with a positive or frictional fit. In particular, it can also be implemented with a positive fit without synchronization in order to make its design particularly simple and compact.

[0015] The electric motor and / or a rotor wheel of the electric motor's rotor are arranged so as to overlap the planetary gear set in the axial direction. This arrangement of the electric motor, which is preferably axially parallel to the input axes of the two spur gear sub-gears and the crankshaft, also allows for a very compact design in the axial direction. According to an advantageous development, the electric motor can be connected via additional transmission elements such as a spur gear, a belt drive, a chain drive, or the like.

[0016] Alternatively, however, the electric machine can also be arranged coaxially, for example coaxially to the planetary gear set, in which case the ring gear of the planetary gear set preferably forms the second shaft, which is coupled to the rotor wheel of the electric machine or directly forms part of the rotor of the electric machine, in such a coaxial arrangement thereof.

[0017] An exceptionally advantageous development of the hybrid drive system according to the invention can now provide for a shifting element for the first spur gear sub-transmission to be arranged coaxially with the countershaft and axially between the spur gear pairs. Such an arrangement of a shifting element for the first spur gear sub-transmission coaxially with the countershaft thus uses a fixed gear in the region of the input shaft in the first spur gear pair and correspondingly an idler gear on the at least one countershaft, according to the embodiment described above of exactly one. In principle, such a shifting element could be arranged coaxially with the countershaft in any axial position. It is particularly preferably located between the two spur gear pairs. The first shifting element then uses the same installation space in the axial direction as the interlocking shifting element, so that no additional installation space is required in the axial direction.

[0018] In the context of the present invention, "coaxial" refers to a rotatably mounted element coaxial with another rotatably mounted element, such as a shaft, such that the axes of rotation of the two elements are congruent or aligned. Furthermore, according to the invention, a gear pair or spur gear pair is understood to mean a number of two intermeshing gears or spur gears which have parallel axes of rotation and are arranged in a common plane, referred to as the gear set plane, with respect to a plane perpendicular to these axes of rotation.

[0019] Ultimately, the four-shaft planetary gear set is designed such that the first shaft represents the summing shaft in relation to the third and fourth shafts as soon as the two spur gear units connected to the third and fourth shafts are actively engaged. Their corresponding shifting elements are therefore closed, and the electric motor does not provide any significant torque. The third shaft of the planetary gear set, which is non-rotatably connected to the first spur gear unit, represents the summing shaft in relation to the second shaft and the first shaft as soon as a gear in the first spur gear unit is actively engaged and the shifting element of the other spur gear unit is open, with the electric motor providing significant torque.

[0020] The vehicle according to the invention comprises a hybrid drive system according to one of the embodiments described above, with an additional electric drive system being provided that is mechanically independent of the hybrid drive system. This makes the drive system very flexible in its use. For example, an electric reverse gear can be implemented in this way, so that the transmission does not need to provide one.

[0021] According to a very advantageous development of this, the vehicle according to the invention can be provided with the hybrid drive system driving one axle of the vehicle, while the electric drive system drives another axle of the vehicle, so that, for example, one axle can be used for starting and reversing in purely electric mode and the other axle can be used for propulsion with the hybrid drive system. Furthermore, both axles can be used if necessary, thus achieving an all-wheel drive system, for example, in a passenger car application.

[0022] The design also allows the power generated in the hybrid drive system during generator operation of the electric machine to be passed on to the purely electric drive system, so that its operation is not dependent on the battery charge level.

[0023] Further advantageous embodiments of the hybrid drive system according to the invention also emerge from the two exemplary embodiments, which are described in more detail below with reference to the figures.

[0024] Showing: Fig. 1 a schematic representation of a possible embodiment of the hybrid drive system according to the invention; Fig. 2 a switching table to explain the possible states of the hybrid drive systems according to the invention in Fig. 1; and Fig. 3 a schematically indicated vehicle with such a hybrid drive system and an additional electric drive system.

[0025] In the presentation of the Fig. 1 shows a hybrid drive system 1, which includes an indicated internal combustion engine 2 and an electric motor 3. A rotor of the electric motor 3 is rotationally fixedly connected to a rotor wheel 6, which is connected via an intermediate gear 7 as a transmission element to a four-shaft planetary gear set 8 of a transmission designated as a whole by 4. The transmission 4 is shown only in its upper half, relative to its main axis of rotation.

[0026] The four-shaft planetary gear set 8 comprises a first shaft or a first element 8.1, which here is formed by the first sun gear. A second element 8.2 is coupled to the intermediate gear 7 and is formed by a ring gear of the planetary gear set 8. In addition to these two shafts 8.1 and 8.2, a third shaft or a third element 8.3 of the planetary gear set 8 is formed by a second sun gear and is rotationally fixedly connected to a first input shaft 9 of a first spur gear sub-transmission B. A web or double web as the fourth shaft or fourth element 8.4 of the planetary gear set 8 is rotationally fixedly connected to a second input shaft 10 of a second spur gear sub-transmission A.

[0027] The first shaft or the first element 8.1 of the planetary gear set 8 can be connected to a crankshaft 5 of the internal combustion engine 2 via a separating clutch K0 and an optional torsional vibration damper 13. When the separating clutch K0 is engaged, the internal combustion engine 2 or its crankshaft 5 can be rotationally coupled to the first shaft 8.1 if necessary.

[0028] The first input shaft 9 drives a first fixed gear FB, which is arranged coaxially and rotationally fixed to the first input shaft, and which drives a first idler gear LB, which together form a spur gear pair 11. This spur gear pair 11 is the only spur gear pair of the first spur gear sub-transmission B, whose idler gear LB is arranged coaxially to a countershaft 12 and, if necessary, can be rotationally fixedly connected to it via a first shift element SB. The second spur gear sub-transmission A comprises an idler gear LA on the second input shaft 10, which is connected to the third shaft 8.3 of the planetary gear set 8 and is coaxial to the first input shaft 9, which is designed as a hollow shaft around the second input shaft 10. A fixed gear FA coaxial to the countershaft 12 then completes a spur gear pair 14 and thus the second spur gear sub-transmission A, which exclusively comprises this one spur gear pair 14.If necessary, the idler gear LA can be connected in a rotationally fixed manner to the second input shaft 10 via a second switching element SA.

[0029] The countershaft 12 in turn carries a driven gear 15 arranged in a section in the axial direction a, which always refers to the axis of rotation of the crankshaft 5 of the internal combustion engine 5 and thus the main axis of rotation of the transmission 4. This gear meshes with a differential 16, indicated schematically here, via which a driven axle 23 of a vehicle 21 equipped with the hybrid drive system 1 (see Fig. 3) is driven.

[0030] The output gear 15 is located between the planetary gear set 8 and the first spur gear sub-gear B. The differential can thus slide axially next to the electric machine 3. However, they could also overlap axially, which is possible due to the gear set plan of the Fig. 1 cannot be represented. However, the differential 16 can be positioned as close as possible to the combustion engine 2, which represents an advantage in terms of installation space.

[0031] Alternatively, it would also be conceivable, with corresponding diameters of the planetary gear set 8 and the spur gear pairs 11, 14, to arrange the output gear 15, which is connected in a rotationally fixed manner to the countershaft 12, in an axially overlapping manner with the planetary gear set 8. This would also allow the differential 16 to be moved very close to the internal combustion engine 2, which advantageously promotes the compact design and the ideal utilization of the installation space typically available in the vehicle 21.

[0032] Both variants make installation across the direction of travel particularly easy.

[0033] Via a brake switching element BA, the second input shaft 10 and thus the fourth element or fourth shaft 8.4 of the planetary gear set 8, which is connected to it in a rotationally fixed manner, can be connected to a housing 17 of the transmission 4 and thus braked. This allows the gear ratio of the planetary gear set 8 to be changed. In the exemplary embodiment shown here, the two switching elements SA, BA are combined to form a combined coupling switching element. This comprises a common synchronizing body and a common sliding sleeve 18. In addition to the design of the switching elements as friction switching elements, which is also conceivable in principle, this variant with a design of the switching elements SA and BA as a combined switching element with a common sliding sleeve 18 and a positive switching via a single actuator is ideal.In terms of its arrangement, it can preferably be arranged, as shown here, on the side of the two spur gear pairs 11, 14 on the second input shaft 10 facing away from the planetary gear set 8. This allows the second input shaft 10 to be either braked or connected to the idler gear LA and, via the second spur gear sub-gearbox A, to the output via the output gear 15.

[0034] Two of the elements of the planetary gear set 8, for example in the embodiment shown here the third shaft 8.3 and the fourth shaft 8.4 or the first input shaft 9 or second input shaft 10 connected to it in a rotationally fixed manner, can be connected to one another via a blocking switching element SK, which in turn is preferably designed as a positive-locking switching element without synchronization. At the corresponding speed of the elements, a relative movement between the elements of the planetary gear set can be realized by connecting the carrier as the fourth element 8.4 with the second sun as the third element 8.3. The planetary gear set 8 then rotates as a block, which is why the switching element SK is commonly referred to as a blocking switching element.

[0035] Both described variants of the embodiment of the hybrid drive system 1 now allow various following based on the table in Fig. 2 explains the states and gear ratios. An x represents a closed clutch or a closed shift element.

[0036] A first combined state in which the hybrid drive system 1 can be influenced by both the internal combustion engine and the electric motor is designated EVT 1. In this case, the torques or speeds of the internal combustion engine 2 and the electric machine 3 are superimposed on the planetary gear set 8, while at the same time the second switching element SA is closed and the first switching element SB is open. This state can occur, for example, for starting off a vehicle with the hybrid drive system 1 in hybrid mode. Both the internal combustion engine 2 and the electric machine 3 are involved. Due to the torque from the internal combustion engine 2 and an initial generator operation of the electric machine 3, the torque that is transmitted to the drive can be increasingly increased depending on the control of the electric machine 3 by correspondingly reducing the generator power at the electric machine 3.This enables electrodynamic starting. Subsequently, the electric machine 3 can then also be operated as a motor. In addition to starting a vehicle with the hybrid drive system 1, the first EVT mode EVT 1 is used, among other things, for active gear ratio adjustment and speed synchronization within the first shift element SB, in particular when changing from a first gear G1 to a second gear G2, which is described below. In the first gear G1, the planetary gear set 8 is then correspondingly blocked by the locking shift element SK being closed. For example, the locking shift element SK can be designed as a positive-locking clutch element, wherein synchronization can take place in a manner known per se when the locking shift element SK is closed by the electric machine 3.

[0037] When changing from the first gear G1 to the second gear G2, on the one hand the interlocking switching element SK is opened and the first switching element SB is closed in addition to the second switching element SA or, in the case of a common sliding sleeve 18, this is moved into the corresponding position.

[0038] In order to move from the second gear G2 into a third gear G3, the second shift element SA is opened and at the same time the blocking shift element SK is closed again so that the two input shafts 9, 10 and the planetary gear set 8 are blocked accordingly.

[0039] In the second EVT mode EVT 2, when the interlocking shift element SK is open, the second shift element SA is open, and the first shift element SB is closed, the speeds and torques of the combustion engine 2 and the electric machine 3 are superimposed accordingly on the planetary gear set 8. This second EVT mode EVT 2 is used in particular to implement a "virtual" fourth and a "virtual" fifth gear. In addition to active gear ratio adjustment, the second EVT mode EVT 2 can also be used for speed synchronization within the interlocking shift element SK when changing from second to third gear if this is designed as a positive shift element without synchronization. In this mode, too, the electric machine can be operated both as a generator and as a motor.

[0040] A subsequent sixth gear G6 now uses the brake shift element BA. With the second shift element SA open and the locking clutch SK open, the power is transmitted via the first spur gear train B.

[0041] The further states, namely a first electric gear E1, a second electric gear E2, and a third electric gear E3, are then electric gears, which are realized with the separating clutch K0 disengaged in the case of E1 with the shift elements SA and SB engaged. When shifting from the first electric gear E1 to the second electric gear E2, the first shift element SB is opened and the planetary gear set 8 is locked. When shifting further to the third electric gear E3, the second shift element SA is opened and the first shift element SB is closed accordingly.

[0042] Not in Fig. 2, but also advantageously possible, is a fourth electric gear in which the separating clutch K0 is open and in which otherwise the same switching elements are closed as in the sixth gear G6.

[0043] The hybrid drive system 1 can now be used in particular to drive a Fig.3. The simple design of the hybrid drive system 1, with its reduced number of required components, makes sense primarily in combination with an additional purely electric drive system 22, which can, for example, form a reverse gear and / or realize starting or support the hybrid drive system 1. In particular, the hybrid drive system 1 and the electric drive system 22 can be arranged such that one, here, for example, the hybrid drive system 1, drives a first driven axle, e.g., the front axle 23, of the vehicle 22, and the electric drive system 22 drives another driven axle, here the rear axle 24.A coupling of the two systems, namely the hybrid drive system 1 and the electric drive system 22, indicated by a double arrow 25, then takes place purely electrically via a drive control device (not shown in detail) and via a battery system (also not shown in detail).

[0044] The electrical support of the drive is still possible even when the battery is largely empty, since the hybrid system 1 can operate its electric machine 3 as a generator in order to supply the electric drive system 22 with power.

Claims

[1] Hybrid drive system (1) with an internal combustion engine (2) and an electric machine (3), and a transmission (4) with a first spur gear sub-transmission (B) and a second spur gear sub-transmission (A), which drive via at least one countershaft (12), and a four-shaft planetary gear set (8), wherein a first shaft (8.1) is coupled or can be coupled to a crankshaft (5) of the internal combustion engine (2), wherein a rotor of the electric machine (3) is coupled, can be coupled to, or is designed as a second shaft (8.2), wherein a first input shaft (9) of the first spur gear sub-transmission (B) is connected in a rotationally fixed manner to a third shaft (8.3), and wherein a second input shaft (10) of the second spur gear sub-transmission (A) is connected in a rotationally fixed manner to a fourth shaft (8.4) of the planetary gear set (8), characterized by , that the first and the second spur gear partial transmission (B, A) each have exactly one spur gear pair (11, 14), and that a blocking switching element (SK) for blocking two of the shafts (8.1, 8.2, 8.3, 8.4) of the planetary gear set (8) in an axial direction (a) along the input shafts (9, 10) is arranged between the two spur gear pairs (11, 14), wherein a brake switching element (BA) is provided for the rotationally fixed connection of the fourth shaft (8.4) of the planetary gear set (8) to a housing (17) of the transmission (4), wherein a second shifting element (SA) and the brake shifting element (BA) are arranged coaxially to the second input shaft (10) and in the axial direction (a) on a side of the two spur gear pairs (11, 14) facing away from the planetary gear set (8), wherein the second switching element (SA) and the brake switching element (BA) are designed as a coupling switching element and can be switched with a single common sliding sleeve. [2] Hybrid drive system (1) according to claim 1, characterized by that the interlocking switching element (SK) is designed as a positive coupling. [3] Hybrid drive system (1) according to claim 1 or 2, characterized by that exactly one countershaft (12) is provided with an output gear (15) connected to it in a rotationally fixed manner. [4] Hybrid drive system (1) according to claim 1, 2 or 3, characterized by that the crankshaft of the internal combustion engine (2) is connected to the first shaft (8.1) of the planetary gear set (8) via a separating clutch (K0). [5] Hybrid drive system (1) according to one of claims 1 to 4, characterized by that the electric machine (3) and / or a rotor wheel (6) connected to its rotor in a rotationally fixed manner is arranged overlapping the planetary gear set (8) as seen in the axial direction (a). [6] Hybrid drive system (1) according to one of claims 1 to 5, characterized bythat a first shift element (SB) is arranged coaxially to the at least one countershaft (12) and in the axial direction (a) between the spur gear pairs (11, 14). [7] Vehicle (21) with a hybrid drive system (1) according to one of claims 1 to 6 and with an additional electric drive system (22). [8] Vehicle (21) according to claim 7, characterized by that a first vehicle axle (23) is driven via the hybrid drive system (1) and a further vehicle axle (24) is driven via the electric drive system (22).

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