powertrain

Abstract

Proposed is a power assembly having an electric machine, an internal combustion engine, a transmission composed of two sub-transmissions, wherein each sub-transmission is assigned a wheel set having a fixed wheel and a movable wheel, which wheel set represents a gear step, and wherein the internal combustion engine can be connected to the transmission via a double clutch and the electric machine can be connected to one of the sub-transmissions, wherein the electric machine is assigned to the sub-transmission.

Description

TECHNICAL FIELD

[0001] The invention relates to a powertrain having an electric machine, an internal combustion engine, a transmission composed of two sub-transmissions, wherein each sub-transmission is assigned a wheel set having a fixed wheel and a movable wheel, which wheel set represents a gear step. The internal combustion engine can be connected to the transmission via a dual clutch. In addition, there is the electric machine, which is selectively fixedly connected to one of the two sub-transmissions. BACKGROUND

[0002] Hybrid powertrains are known in various variants in the prior art. They comprise a transmission in the form of a spur gear or planetary gear transmission, a drive motor such as an internal combustion engine and a further drive motor such as an electric machine, so that the respective drive powers of the two machines can be combined or transmitted individually to the driven device.

[0003] The internal combustion engine can generally be coupled to the transmission by means of a start clutch, while the electric machine is connected to the powertrain at different points as required.

[0004] If the electric machine is arranged between the internal combustion engine and the transmission or is coupled directly to the transmission, the gear steps of the internal combustion engine can be used at least partially together with the electric machine. The following advantage arises therefrom: the electric machine can be simply added to an existing transmission without great outlay.

[0005] A powertrain is also known from the prior art, in which the electric machine is coupled to the driven device, which is referred to as a parallel hybrid in the P3 configuration.

[0006] The connection is generally made by means of a traction mechanism transmission, a spur gear stage or a planetary gear set, wherein the following transmission stage is preferably selected, in which the electric machine can be operated in a high-efficiency, high-speed range.

[0007] A plurality of embodiments of a simpler dual-clutch transmission with four gear steps and an input device of an electric machine are known from DE 10 2016 007 408 A1. Here, the gear steps are shown by wheel pairs, which are arranged on one sub-transmission for the first and third gear steps and on a second sub-transmission for the second and fourth gear steps. Different driving scenarios can be shown by using fixed wheels and movable wheels and shift clutches.

[0008] The arrangement of the transmission assembly in combination with the fixedly connected electric machine on one of the two sub-transmissions does not allow a gear shift without traction interruption in the case of pure electric driving.

[0009] A transmission is described in DE 10 2019 211 449 A1, as in Figure 1The principle shown in Fig. 1 is shown in DE 10 2016 207 221 A1. Here, the electric motor is connected to a separate input wheel in one of the sub-transmissions. This electric input wheel takes up space on the respective input shaft of the transmission. The overall length of the transmission is thus increased. Furthermore, the diameter of the electric input wheel on the respective input shaft is also limited by the synchronizing unit near the output shaft. The transmission ratio between the electric motor and the transmission input shaft is thus limited. The transmission ratio of the electric motor cannot therefore reach the sought value of approximately 2.7, but is limited to a value of approximately 1.7-1.9.

[0010] A functional deficiency thus arises with respect to the charging of the battery and with respect to the energy recovery power when creeping.

[0011] From DE 10 2016 207 221 A1, a powertrain is known which connects an electric motor on a first sub-transmission, wherein a second gear is used. The electric sub-transmission here has gears 2 and 4. The fifth gear is represented via the stationary wheel of the third gear.

[0012] From DE 10 2011 088 593 A1, a drive device with a dual clutch transmission is known, which has three wheels, a stationary wheel and one movable wheel for each input shaft. This arrangement requires a large axial installation space.

[0013] DE 10 2016 007 408 A1 shows a dual clutch transmission with an electric motor, which is connected to one of the sub-transmissions. The movable wheels for representing gears 1 to 4 are here concentrated on one of the intermediate shafts, so that the axial extension is correspondingly large. SUMMARY

[0014] It is an object of the present application to produce an improved transmission device, a short hybrid transmission, which is power shiftable, with an optimized transmission ratio for the electric input.

[0015] The object is achieved by means of a powertrain having an electric motor, an internal combustion engine, a transmission composed of two sub-transmissions, wherein each sub-transmission is assigned a wheel set with a stationary wheel and a movable wheel, which represents a gear, and wherein the internal combustion engine can be connected to the transmission via a dual clutch with a clutch, and the electric motor can be connected to the first sub-transmission, wherein the first sub-transmission with a first drive shaft can be connected to the internal combustion engine via a clutch, and has a stationary wheel for a fourth gear and a stationary wheel for a second gear in the direction away from the internal combustion engine, and the second sub-transmission has a first gear and a third gear, wherein the fourth gear is arranged axially between the third gear and the bridge clutch, and serves to drive the electric motor, the bridge clutch is arranged between the second and fourth gears, wherein the stationary wheel of the fourth gear enters the gap between the stationary wheel of the third gear and the bridge clutch.

[0016] By means of the synchronization between the movable wheel of the second and third gear, the two sub-transmissions can be coupled, so that in addition to the four physical gears, two further gears can be shown. One of the gears is transmitted in a shorter way than the physical first gear, one of the additional gears is transmitted in a longer way than the physical fourth gear.

[0017] By means of the axial unfolding of the construction space between the bridge clutch and the third gear, a gap is provided. Here, the larger gearwheel can enter into the first driven shaft.

[0018] By using the fourth gear twice as an electrical input wheel, even a total of about 10 mm of axial construction space can be saved.

[0019] Therefore, the movable wheel for the fourth gear is moved to the second output shaft, where the unused side of the reverse gear synchronization is used.

[0020] Depending on the wheelbase and the requirements regarding the transmission ratio of the reverse gear and the highest gear, the first gear and the reverse gear can also be exchanged between the shafts. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application is described below by way of example with reference to the drawings.

[0022] Figure 1 A schematic diagram of a hybrid transmission with six gears and the connection of the electric machine on the input shaft via a dedicated gearwheel is shown.

[0023] Figure 2 A second embodiment of the hybrid transmission is shown. DETAILED DESCRIPTION

[0024] In Figure 1 The powertrain 1, which has an internal combustion engine VM, which is connected with a dual clutch, can be seen in Fig. 1. The dual clutch is composed of two clutches Kl and K2, which can be operated independently of one another. Furthermore, the powertrain has a transmission 5 with two sub-transmissions TGl and TG2, which are arranged along the drive shafts Al and A2. The gears 2 and 4 with the fixed wheels F3 and F5 are arranged on the drive shaft Al associated with the first sub-transmission TGl.

[0025] On the second sub-transmission TG2, the wheel sets for gears 3 and 1 are mounted on drive shaft A2 with fixed wheels F4 and F2. Driven shaft 7 carries a unilateral shift clutch S2, which couples the movable wheel L3 for second gear, and the movable wheels for third gear L4 and reverse gear LR, which are connected to driven shaft 7 via shift clutch S1. A shift clutch B is axially located in the plane between second and fourth gears, i.e., between fixed wheel F5 and movable wheel L5, and between fixed wheel F3 and movable wheel L3, which connects the movable wheels L3 and L4 for gears 2 and 3, thus connecting the two sub-transmissions TG1 and TG2. Driven shaft 7 connects the output energy of transmission 5 to the vehicle's drive wheels via wheel set 6, for example, via a differential. Another second driven shaft 8 carries two movable wheels L5 and L2 for gears 4 and 1, which can be switched via shift S3, and can optionally carry a parking lock P.

[0026] A gap is provided between the fixed wheel F4 (third gear) and the bridge clutch B, which are arranged axially along the drive shafts A1 and A2 via fixed and movable wheels. The fixed wheel F5 (fourth gear) enters this structural space and also serves as the electric input wheel on the input shaft A1, via which the electric drive motor EM is connected.

[0027] For pure electric operation via electric motor EM, internal combustion engine VM is decoupled from the powertrain by keeping clutch K1 disengaged. Gears 2, 4, and reverse can be shifted electrically through different shift positions of shift clutches S1, S2, and S3. For reverse, clutch K2 must also be forcibly disengaged.

[0028] The gear ratios of gears 2 and 3 can also be used to increase the torque of the motor EM on the clutch via the closed shift clutch B, so as to be able to start the motor while resisting high motor drag torque.

[0029] The second sub-transmission TG2 has first and third gears.

[0030] The fixed wheel F2 of the first gear position is connected to the movable wheel L2 of the first gear position on the second driven shaft 8. The movable wheel L2 engages with the reverse gear wheel LR located on the first driven shaft 7.

[0031] according to Figure 2 In this implementation, the movable wheels for first gear and reverse gear are interchanged.

[0032] The axial arrangement of the bridge clutch and the fourth gear can also be interchanged. However, more favorable conditions are created if the first and fourth gears are located on the second output shaft 8.

[0033] A non-power shift sixth gear can still be added on the shaft end of the output shaft 7.

Claims

1. A powertrain (1) having an electric machine (EM), an internal combustion engine (VM), a transmission (5) composed of a first sub-transmission (TG1) and a second sub-transmission (TG2), and wherein the internal combustion engine (VM) is connectable to the transmission (5) via a dual clutch with two clutches (K1, K2) and the electric machine (EM) is connectable to the first sub-transmission (TG1), wherein the first sub-transmission (TG1) with a first drive shaft (Al) is connectable to the internal combustion engine (VM) via the first drive shaft and a first clutch (K1) and has a fixed wheel (F5) for a fourth gear and a fixed wheel (F3) for a second gear on the first drive shaft in the axial direction away from the internal combustion engine, the second sub-transmission (TG2) with a second drive shaft (A2) is connectable to the internal combustion engine (VM) via the second drive shaft and a second clutch (K2), the first sub-transmission (TG1) and the second sub-transmission (TG2) are arranged along the first drive shaft (Al) and the second drive shaft (A2), respectively, and the second sub-transmission (TG2) has a fixed wheel (F2) for a first gear and a fixed wheel (F4) for a third gear on the second drive shaft, a movable wheel (L3) for a second gear and a movable wheel (L4) for a third gear are arranged on a first driven shaft (7) of the transmission, a movable wheel (L5) for a fourth gear is arranged on a second driven shaft (8) of the transmission, and a movable wheel (L2) for a first gear is arranged on the first driven shaft (7) or the second driven shaft (8) of the transmission, characterized in that The fourth gear stage with a fixed wheel (F5) and a movable wheel (L5) is arranged axially between the third gear stage and the bridge clutch (B) and serves to drive the electric machine (EM), the bridge clutch being arranged on the first output shaft (7) of the transmission between the movable wheel (L3) of the second gear stage and the movable wheel (L4) of the third gear stage, wherein the bridge clutch can connect the movable wheel of the second gear stage and the movable wheel of the third gear stage and in turn the first sub-transmission (TG1) and the second sub-transmission (TG2), wherein the fixed wheel (F5) of the fourth gear stage enters into the gap between the fixed wheel (F4) of the third gear stage and the bridge clutch (B), the fixed wheel of the fourth gear stage simultaneously serving as an electrical input wheel on the first drive shaft (A1), connecting the electric machine (EM) via the first drive shaft.

2. The powertrain of claim 1, wherein, The movable wheel (L2) of the first gear stage on the second output shaft (8) is the first-gear-stage-representing part of a gear pair.

3. The powertrain of claim 1, wherein, The movable wheel (LR) of the reverse gear is arranged on the second output shaft (8) or on the first output shaft (7) of the transmission and is arranged on a different output shaft than the movable wheel (L2) for the first gear stage.

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