Hybrid drivetrain

Abstract

Hybrid drive train (10) for a motor vehicle, comprising an input shaft arrangement having a first input shaft (18) and a second input shaft (20), wherein the first input shaft (18) is connected to a second friction clutch (K2), wherein the second input shaft (20) is connected to a first friction clutch (K1), and wherein the second input shaft (20) is arranged as a hollow shaft around the first input shaft (18), - a second partial transmission (TG2) associated with the first input shaft (18) and a first partial transmission (TG1) associated with the second input shaft (20), - a first output shaft (30) and a second output shaft (32), wherein an output gear (34, 22) is provided on each of the output shafts (30, 32), - a plurality of gear sets serving to establish gear stages (1-5, R), each of which connects the input shaft arrangement to the first output shaft (30) and / or to the second output shaft (32), wherein the first input shaft (18) has two fixed gears and the second input shaft (20) has two further fixed gears, and - an electrical machine (EM) coupled to one of the partial transmissions, wherein a loose wheel of a high-ratio gear stage, the reverse gear stage (R), is arranged on the second output shaft (32), wherein a connection (A2) connects the idler gear of the second gear stage on the first output shaft (30) to a bridge gear (B) of the second output shaft (32) and the bridge gear (B) establishes a connection to the idler gear of the reverse gear stage (R) via a synchronizer unit (S1) on the second output shaft (32), wherein a connection (A3) connects the idler gear (RL) of the first gear stage of the first output shaft (30) to the idler gear of the reverse gear stage (R) of the second output shaft (32).

Description

[0001] The present invention relates to a hybrid drive train for a motor vehicle, comprising a first drive unit for providing a first drive power for driving the motor vehicle and a second drive unit for providing a second drive power for driving the motor vehicle, and comprising a transmission arrangement connected to the first drive unit and to the second drive unit for supplying drive power to a transmission output in different gear ratios.

[0002] Different concepts are known in the field of hybrid powertrains.

[0003] In dual-clutch transmissions, it is known to connect an electric motor to one of the two sub-transmissions, specifically downstream of the input-side friction clutches (dual clutch) in the direction of power flow. In this embodiment, purely electric driving is possible via one of the sub-transmissions. Furthermore, power can be transmitted from the first drive unit (combustion engine) via the sub-transmission assigned to the electric motor, such that the power of the first and second drive units can be superimposed on the same power transmission path.

[0004] However, such transmissions also allow for a so-called torque-split mode of operation. Here, power is delivered to the transmission output via different power transmission paths. For example, electrical power is delivered to the transmission output via one sub-transmission, and combustion engine power is delivered to the transmission output via the other sub-transmission, so that the drive powers at the transmission output are summed. This enables a variety of other operating modes, including traction assistance via the electric motor during gear changes, a coasting mode in which the electric motor is switched off and the electric motor supplies power as needed to maintain a certain speed, etc.

[0005] In general, hybrid powertrains can be designed so that drive power is provided primarily by the first drive unit in the form of an internal combustion engine, with the second drive unit in the form of an electric motor being used only for support or for very short distances. Other hybrid powertrains are designed so that the power of the internal combustion engine and the electric motor can be of the same order of magnitude. This also depends largely on the size of the battery integrated into the powertrain.

[0006] Generally, driving with an internal combustion engine requires a relatively large number of gears (gear ratios) to allow the engine to operate within a favorable speed range. An electric motor generally requires significantly fewer gears.

[0007] Some hybrid powertrains don't have a dedicated reverse gear for combustion engine propulsion to save weight. Reversing with such powertrains is only possible using the electric motor, whose rotation direction is then reversed.

[0008] In general, there is a need for hybrid powertrains that are simple and cost-effective to implement and that ensure the greatest possible range of functionality.

[0009] DE 10 2016 119 931 B4 discloses a dual-clutch transmission with a bridge shaft, which serves to implement reverse gear and a first gear. This transmission is driven solely by an internal combustion engine.

[0010] From EP 3 241 701 A1, a hybrid drive train is known with a first drive unit for providing a first drive power for driving the motor vehicle, with a second drive unit for providing a second drive power for driving the motor vehicle, and with a transmission arrangement which is connected to the first drive unit and to the second drive unit, wherein the transmission arrangement has a first partial transmission, by means of which the first drive power can be guided to a transmission output with at least two different (forward gear) ratios, and a second partial transmission, by means of which the second drive power can be guided to the transmission output with at least two different (forward gear) ratios, wherein the transmission arrangement has a first input shaft and a second input shaft,wherein the first input shaft is connected to the first drive unit and wherein the second input shaft is connected to the second drive unit, wherein the first partial transmission and the second partial transmission are connectable to one another via a bridge clutch, and wherein the second drive unit has an electric machine which is connected to the second input shaft via a drive spur gear set.

[0011] Pure driving operation with the first drive unit is possible via two gear ratios of the first sub-transmission and, with the bridge clutch engaged, also via the two gear ratios of the second sub-transmission. Consequently, forward driving operation with the first drive unit can be established via at least four gear ratios, which are preferably coordinated with one another in the manner of gear stages 1, 2, 3, and 4.

[0012] The first partial transmission contains a gear set that enables reverse driving, so that reversing is also possible using the combustion engine alone.

[0013] DE 10 2018 220 592 A1 shows a transmission with a first shaft, a second shaft, a third shaft, at least one countershaft, a first shifting element, a second shifting element, and a shifting element for a winding gear.

[0014] The second and third shafts define sub-transmissions. The second shaft forms the input shaft of one sub-transmission, and the third shaft forms the input shaft of another sub-transmission.

[0015] The first shaft preferably serves as the input shaft of the transmission. It can be driven, for example, by an internal combustion engine. The first shaft and the second shaft can be connected to each other in a rotationally fixed manner via the first shifting element. The first shaft and the third shaft can be connected to each other in a rotationally fixed manner via the second shifting element.

[0016] The current state of the art proposes dissolving the partial transmission coupling of the winding gear using an additional shaft and an additional shifting element. The torque flow of the winding gear is directed via the additional shaft. Thus, the second shaft and the additional shaft can be connected to each other for rotation, preferably in the same direction, via the shifting element for the winding gear. The third shaft and the additional shaft can be connected to each other for rotational connection via the additional shifting element.

[0017] DE 10 2019 215 114 A1 shows a hybrid drive train for a motor vehicle, with an input shaft arrangement having a first input shaft and a second input shaft, wherein the first input shaft is connected to a first friction clutch, wherein the second input shaft is connected to a second friction clutch, and wherein the second input shaft is arranged as a hollow shaft around the first input shaft, with a second partial transmission assigned to the first input shaft, and a first partial transmission assigned to the second input shaft, a first output shaft and a second output shaft, wherein an output gear is provided on each of the output shafts, a plurality of gear sets serving to establish gear stages, each of which connects the input shaft arrangement to the first output shaft and / or to the second output shaft, and an electric machine coupled to one of the partial transmissions,wherein a high-ratio gear stage is arranged on the second output shaft, which can be used for reverse gear and, in the case of a K0, also for a purely electric creeper gear.

[0018] DE 101 33 695 A1 shows two parallel, offset input shafts, each with fixed gears for more than two gear steps. Six separate forward gears and one separate reverse gear are provided. A high-ratio gear or reverse gear is not provided.

[0019] US 2018 / 0 029 462 A1 shows a transmission with concentric input shafts connected to a dual clutch. An electric motor is arranged coaxially with an internal combustion engine on the input side, upstream of the dual clutch. The first input shaft carries two fixed gears, the second input shaft carries three. Seven synchronizers are used to engage the different gears.

[0020] DE 10 2019 004 762 B3 shows a hybrid transmission with concentric input shafts and a dual clutch, with the electric motor located upstream of the dual clutch transmission on the input side. To form a reverse gear, a third gear arranged coaxially with a second countershaft is permanently meshed with a first gear arranged coaxially with a first countershaft.

[0021] DE 10 2012 009 484 B3 shows a hybrid transmission in which the electric machine is connected to a partial transmission.

[0022] The object of the invention is to provide a hybrid transmission which has a high-ratio drive gear for both electric and combustion engine operation, which at the same time serves as a very high-ratio gear for the electric drive, wherein a further high-ratio gear is provided.

[0023] The object is achieved with a hybrid drive train for a motor vehicle with an input shaft arrangement which has a first input shaft and a second input shaft, wherein the first input shaft is connected to a first friction clutch, wherein the second input shaft is connected to a second friction clutch and wherein the second input shaft is arranged as a hollow shaft around the first input shaft, - a second partial transmission associated with the first input shaft and a first partial transmission associated with the second input shaft, - a first output shaft and a second output shaft, each output shaft having an output gear, - a plurality of gear sets serving to establish gear stages, each of which connects the input shaft arrangement to the first output shaft and / or to the second output shaft, and - an electrical machine coupled to one of the partial transmissions, wherein a fixed gear for a high-ratio gear stage for the reverse gear is arranged on the second input shaft, wherein a bridge circuit switchably connects a bridge gear, which is connected via two tooth engagements to the first gear stage of the first input shaft, to a fixed gear of the second gear stage of the second input shaft and thus to the reverse gear stage of the second input shaft.

[0024] This allows for simple multi-use of a gear ratio, allowing the high-ratio gear for the first sub-transmission to be used as a crawler gear for special maneuvers. It represents an additional driving gear in the first sub-transmission. The gear ratio can also be used for both the combustion engine and the electric motor if a separating clutch is present.

[0025] A bridge coupling connects the two input shafts via claw couplings or synchronizer units, which saves space.

[0026] It is advantageous that the bridge clutch uses a switching unit on the second output shaft.

[0027] For this purpose, an additional switching unit is installed for each sub-transmission.

[0028] The arrangement is either such that the first sub-transmission contains even gears and is mounted closer to the dual clutch than the second sub-transmission, which contains the odd gears, or vice versa.

[0029] The electric motor is connected to the first or second partial transmission.

[0030] The method according to the invention for operating a hybrid powertrain uses the transmission design, wherein reverse travel with the combustion engine is established via the high-ratio gear stage, as well as a reverse and forward gear stage for the electric machine. Example of the invention

[0031] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1: a schematic representation of an embodiment of a hybrid drive train according to the invention.

[0032] In Fig. 1, a hybrid powertrain is shown schematically and generally designated 10.

[0033] The hybrid drivetrain 10 has a first drive unit in the form of an internal combustion engine (ICE). The internal combustion engine (ICE) provides a first drive power for driving a motor vehicle. The hybrid drivetrain 10 further includes a second drive unit in the form of an electric motor (EM). The second drive unit also provides drive power for driving the motor vehicle.

[0034] The hybrid powertrain 10 further includes a transmission assembly 16 connected to the internal combustion engine (ICE) and the electric motor (EM). The transmission assembly 16 has a dual clutch including a first friction clutch K1 and a second friction clutch K2. The two clutches have a common input element 40 connected to the internal combustion engine (ICE). A further separating clutch K0 is shown in dashed lines; in one embodiment, it is installed between the dual clutch and the internal combustion engine.

[0035] The transmission arrangement 16 has a first input shaft 18 which is fixedly connected in the form of an inner shaft to an output member of the second friction clutch K2.

[0036] The first input shaft 18 is assigned to a second sub-transmission TG2 with gear stages 4 and 2 and carries the fixed gears of the second and third gear stages. The transmission arrangement 16 further comprises a second input shaft 20, which is designed as a hollow shaft aligned concentrically with the first input shaft 18. The second input shaft 20 is fixedly connected to an output member of the first friction clutch K1 and carries the fixed gears of the first and fifth gear stages. The second input shaft 20 is thus assigned to a first sub-transmission TG1, which comprises gear stages 5 and 1.

[0037] The transmission assembly 16 further includes a transmission output 22, which is suitably coupled to a differential for distributing drive power to driven wheels. The transmission output 22 is arranged on a first output shaft 30.

[0038] The transmission assembly 16 has a second output shaft 32. The second output shaft 32 has a rigidly fixed output gear 34 as a second transmission output, which meshes, for example, with a differential gear.

[0039] The second output shaft 32 also has a gear set 3 for forming a third gear, as well as a gear set R for providing a reverse gear and, if a K0 is present, also a high-ratio electric creeper gear. A parking lock gear P, indicated by the dashed line, is located on the second output shaft 32 and can be installed.

[0040] A plurality of gear sets 1, 2, 3, 4, 5, R for establishing different gear ratios are arranged between the input shaft arrangement, which consists of the first input shaft 18 and the coaxial second input shaft 20 arranged around it as a hollow shaft, and the output shafts 30 and 32. The gear sets 1, 2, 3, 4, 5, R each have a fixed gear connected to one shaft and an idler gear rotatably mounted on the other shaft, which can be connected to the associated shaft via a respective clutch in order to establish a gear ratio. Synchronizer units S1, S2, S3, S4 are provided between every two gear ratios and serve to engage and synchronize the gear ratios.

[0041] The structure of the first output shaft 30, viewed from the side of the internal combustion engine (ICE), includes the transmission output 22, followed by an idler gear comprising a gear for the first gear stage, as well as a gear serving as the idler gear RL for the reverse gear. The idler gear RL is designed as a double gear RL-1. The idler gear of the fifth gear stage, the idler gear of the second gear stage, the synchronization S2, and the idler gear of the fourth gear stage follow via the synchronization S3.

[0042] The structure of the second output shaft 32, seen from the side of the internal combustion engine VKM, shows the output gear 34, followed by the idler gear of the reverse gear RL, the synchronization S4, the idler gear of the third gear stage, a bridge gear B and the synchronization S1.

[0043] The electric motor is connected to a gear set of the second sub-transmission TG2, e.g., to the fixed gear of the fourth gear stage, via a spur gear set 2 and a connection A1. A connection A2 connects the idler gear of the second gear stage on the first output shaft 30 to the bridge gear B of the second output shaft 32.

[0044] A connection A3 connects the idler gear RL on the first output shaft 30 with the idler gear of the reverse gear stage Rauf on the second output shaft 32.

[0045] In the Fig. 1 shows the torque flow for forward driving with the combustion engine ICE with high gear ratio.

[0046] For this purpose, the second friction clutch K2 is engaged to connect the combustion engine ICE to the second sub-transmission TG2. A connection to the bridge gear B is established via the idler gear for the second gear stage 2 and the connection A2. This is shifted via the synchronizer unit S1 to the idler gear of the third gear set 3, which is rotationally connected to the fixed gear for the fifth gear stage 5 on the second input shaft 20. The input shaft 20 rotates in the opposite direction to the rotation of the input shaft 18. The fixed gear for the first gear stage 1 is also driven by the transmission of torque to the second input shaft 20.

[0047] The fixed gear of gear stage 1 transmits the torque to the idler gear of the first gear stage of the first output shaft 30 and thus to the double gear RL-1

[0048] The idler gear RL is connected to the idler gear of the reverse gear stage R via connection A3 and drives the second output shaft 32 via the synchronizer unit S4. The reversed drive of the input shaft 20 thus creates a high-ratio forward gear.

[0049] This high-ratio crawler gear serves as a high-ratio crawler gear and has a ratio greater than 40, allowing the vehicle to move safely even on steep inclines and under heavy loads. This high-ratio crawler gear allows vehicles with small electrical energy storage units to travel on very steep inclines and with heavy towing loads.

[0050] If, instead of the idler gear of the reverse gear stage R with the synchronizer unit S4, the fixed gear of the gear stage 1 is connected to the output shaft 30 via the synchronizer unit S3, a high-ratio reverse gear can be realized as an alternative.

[0051] The design of the transmission according to the invention enables optimized use of installation space with a reduced number of components and the use of four synchronous units for all functionalities.

[0052] The method according to the invention uses the transmission structure as described to implement various functionalities. For example, multi-stage detents are provided for the gear selector lever in the vehicle to implement the driver's input accordingly.

[0053] Alternatively, other control elements are also conceivable for implementing the driver's wishes. By selecting the desired functionality, the transmission control system performs the shifts described above.

[0054] The gear ratio arrangement described is exemplary and can be changed. It is also possible to swap the sub-gearboxes and connect the electric motor to the sub-gearbox with the odd-numbered gear ratios.

[0055] A particularly advantageous variant uses a separating clutch K0 between the combustion engine VKM and the double clutch K1, K2.

[0056] Due to the transmission concept, it is advisable to operate the shifting system using shift drums for each sub-transmission TG1, TG2 and at the same time to actuate a synchronization-based K0 together with the shift drum of the electric sub-transmission.

[0057] When using the K0 clutch, the transmission can also perform an e-Powershift between two gears in purely electric mode. Furthermore, the K0 clutch allows the internal combustion engine (ICE) to be started in crawl mode at low speeds.

Claims

[1] Hybrid drive train (10) for a motor vehicle, with an input shaft arrangement having a first input shaft (18) and a second input shaft (20), wherein the first input shaft (18) is connected to a second friction clutch (K2), wherein the second input shaft (20) is connected to a first friction clutch (K1), and wherein the second input shaft (20) is arranged as a hollow shaft around the first input shaft (18), - a second partial transmission (TG2) associated with the first input shaft (18) and a first partial transmission (TG1) associated with the second input shaft (20), - a first output shaft (30) and a second output shaft (32), wherein an output gear (34, 22) is provided on each of the output shafts (30, 32), - a plurality of gear sets serving to establish gear stages (1-5, R), each of which connects the input shaft arrangement to the first output shaft (30) and / or to the second output shaft (32), wherein the first input shaft (18) has two fixed gears and the second input shaft (20) has two further fixed gears, and - an electrical machine (EM) coupled to one of the partial transmissions, wherein a loose wheel of a high-ratio gear stage, the reverse gear stage (R), is arranged on the second output shaft (32), wherein a connection (A2) connects the idler gear of the second gear stage on the first output shaft (30) to a bridge gear (B) of the second output shaft (32) and the bridge gear (B) establishes a connection to the idler gear of the reverse gear stage (R) via a synchronizer unit (S1) on the second output shaft (32), wherein a connection (A3) connects the idler gear (RL) of the first gear stage of the first output shaft (30) to the idler gear of the reverse gear stage (R) of the second output shaft (32). [2] Hybrid drive train (10) according to claim 1 with a separating clutch (K0) between the internal combustion engine (VKM) and the first and second friction clutch (K1, K2), wherein the idler gear of the high-ratio gear stage, the reverse gear stage (R) arranged on the second output shaft (32) can be used for the reverse gear and also for a purely electric creep gear. [3] Hybrid drive train (10) according to claim 1 or 2, characterized by that an additional synchronizer unit (S2, S3) is installed for each partial gearbox (TG1, TG2). [4] Hybrid drive train (10) according to one of the preceding claims, characterized bythat the first partial transmission (TG1) contains odd gear stages and is mounted closer to a double clutch (K1, K2) than the second partial transmission (TG2), which contains the even gear stages. [5] Hybrid drive train (10) according to claim 4, characterized by that the electric machine (EM) is connected to the second partial transmission (TG2). [6] Hybrid drive train (10) according to one of the preceding claims, characterized by that the sub-gearboxes (TG1, TG2) are swapped and the electric machine (EM) is connected to the sub-gearbox with the odd gear stages. [7] Hybrid drive train (10) according to one of the preceding claims, characterized by that the idler gear of the first gear stage (1) on the first output shaft (30) together with the idler gear (RL) of the reverse gear form a double gear (RL-1). [8] Method for operating a hybrid drive train according to claim 7, wherein a forward and reverse drive with the internal combustion engine (VKM) is set up via the high-ratio gear stage, the reverse gear stage (R) with the double wheel (RL-1), as well as a reverse and forward gear stage for the electric machine (EM).

Images