Hybrid powertrain for operating a hybrid powertrain

Abstract

A hybrid drive train for a vehicle with at least one internal combustion engine (1), with at least one gear transmission with at least two partial transmissions (3, 4) for shifting without interruption of traction, each having at least one shiftable gear stage, with a plurality of electric machines (EM1, EM2), wherein at least two partial transmissions (3, 4) are each assigned at least one electric machine (EM1, EM2) which is operatively connected or can be brought into operative connection with the internal combustion engine (1), and with at least one energy storage device (6) and with at least one control electronics unit (7) for controlling the electric machines (EM1, EM2), wherein at least one electric machine (EM1, EM2) assigned to a partial transmission (3, 4) can be brought into operative connection with the internal combustion engine (1) via at least one positive shifting element (K1, K2), wherein positive gear stage shifting elements (KL1, KL2, KL3,KL4) are provided, and wherein shifting elements (K1, K2, KL1, KL2, KL3, KL4) assigned to the partial transmissions (3, 4) can be switched by means of a common actuating device, characterized in that for actuating the shifting elements (K1, K2, KL1, KL2, KL3, KL4), partial transmission shafts (10, 11) and / or side shafts (12, 12A, 13, 13A) of the partial transmissions (3, 4) are designed to be axially displaceable.

Description

[0001] The present invention relates to a hybrid drive train according to the type defined in more detail in the preamble of patent claim 1.

[0002] For example, the publication DE 10 2008 002 381 A1 describes a hybrid drive train for a motor vehicle and a method for operating the same. The hybrid drive train comprises an internal combustion engine, two electric motors, and a multi-speed transmission with a transmission input shaft and a transmission output shaft. The internal combustion engine and the first electric motor are permanently connected to the transmission input shaft of the multi-speed transmission, while the transmission output shaft and the associated second electric motor are connected to the drive axle of the vehicle via a fixed gear ratio. Depending on the selected gear ratio, this results in either the disadvantage that the electric motor must be dimensioned accordingly with regard to its power or a fuel consumption disadvantage arises during vehicle operation.

[0003] Furthermore, WO 2007 / 042 109 A1 discloses a dual-clutch transmission for a motor vehicle with a hybrid drive and a method for controlling the same. The two sub-transmissions of the dual-clutch transmission can be coupled to the combustion engine via friction shifting elements of the dual clutch for shifting without interruption in traction. The starting process is realized via at least one friction shifting element of the dual clutch. Each sub-transmission is assigned an electric motor as a hybrid drive. The use of the complex friction shifting elements of the dual clutch, which operate with slipping during starting and shifting, results in a particularly high installation space requirement for the known hybrid drive train. Furthermore, a hydraulic circuit with the corresponding components is required for the hydraulic actuation of the dual clutch, which further increases the installation space requirement.In addition, the heat-generating and thus energy-consuming synchronization in the dual clutch when starting off and shifting results in increased vehicle consumption.

[0004] Another hybrid vehicle with an internal combustion engine, two synchronous motor generators, and a transmission is known from DE 11 2007 002 938 T5. The transmission comprises several shift elements that can be switched via a common actuating device.

[0005] DE 10 2006 036 758 A1 discloses an automated dual-clutch transmission of a motor vehicle which is equipped with two coaxial or axially parallel input shafts, with at least one output shaft arranged axially parallel to the input shafts and with unsynchronized gear clutches.

[0006] The present invention is based on the object of proposing a hybrid drive train which is optimized with regard to consumption, driving performance, comfort and the required installation space.

[0007] The object of the invention is achieved by the features of patent claim 1. Further advantageous embodiments emerge from the respective subclaims and the drawings.

[0008] The object underlying the invention is achieved in terms of device by a hybrid drive train for a vehicle, comprising at least one internal combustion engine, at least one gear transmission with at least two sub-transmissions for shifting without interruption in traction, each having at least one shiftable gear stage, a plurality of electric machines, wherein at least two sub-transmissions are each assigned to at least one electric machine that is or can be operatively connected to the internal combustion engine, and at least one energy storage device and control electronics for controlling the electric machines. Furthermore, at least one electric machine assigned to a sub-transmission can be operatively connected to the internal combustion engine via at least one positive shifting element, wherein the sub-transmissions are assigned positive gear stage shifting elements for shifting the respective gear stages.In order to optimise, in particular, the required installation space, it is provided that predetermined switching elements assigned to the sub-transmissions can each be switched by means of a common actuating device.

[0009] A hybrid drivetrain is implemented with, for example, two sub-transmissions, in which the required active connections between the combustion engine and the sub-transmissions are realized by using only one switching element, with the other active connection, for example, being non-switchable. Overall, in addition to the advantages of a hybrid drivetrain with sub-transmissions, this also results in lower construction costs and significant fuel savings for the vehicle.

[0010] In the proposed hybrid powertrain, a common actuating device can be provided for shifting a gear shifting element of a first gear stage of a first sub-transmission and for shifting a gear shifting element of a third gear stage of the first sub-transmission. For this purpose, a shift fork of the gear shifting element of the first gear stage and a shift fork of the gear shifting element of the third gear stage can be actuated via the common actuating device.

[0011] In the proposed hybrid powertrain, a further common actuating device can be provided for shifting a gear shifting element of a second gear stage of a second sub-transmission and for shifting a gear shifting element of a fourth gear stage of the second sub-transmission. For this purpose, a shift fork of the gear shifting element of the second gear stage and a shift fork of the gear shifting element of the fourth gear stage can be actuated via the common actuating device.

[0012] In the proposed hybrid drive train, a further common actuating device can be provided for switching a first shifting element assigned to the first sub-transmission and for switching a second shifting element assigned to the second sub-transmission. For this purpose, a shift fork of the first shifting element and a shift fork of the second shifting element can be actuated via the common actuating device.

[0013] Within the scope of an advantageous embodiment, it can be provided that, for example, the first electric machine assigned to the first partial transmission is operatively connected to the combustion engine via the positive switching element in order to realize the switchable operative connection, and the second electric machine assigned to the second partial transmission is constantly or continuously operatively connected to the combustion engine. In this embodiment with only one switchable operative connection, the power dimensioning of the first electric machine can preferably be selected to be higher, since this first electric machine can preferably realize starting, load transfer during shifting, and cold start assistance due to the higher drag torque in the combustion engine in cold conditions.The second electric motor can be significantly smaller in terms of power, as it is used only for engine starting and synchronization, for example. For example, this second electric motor can be positioned in front of or near the combustion engine.

[0014] In order to be able to decouple the second electric machine from the combustion engine, for example, during driving in the odd-numbered gear ratios assigned to the first partial transmission, a further advantageous embodiment of the invention provides that, in addition to the first switchable operative connection between the combustion engine and the first electric machine assigned to the first partial transmission, a further switchable operative connection can be established between the second electric machine assigned to the second partial transmission and the combustion engine via at least one second positive switching element. In this embodiment, in which two switchable operative connections are provided, identical power dimensioning for the two electric machines is possible.

[0015] In addition to the electric motors assigned to each sub-transmission, further electric motors, for example, which may not be assigned to a sub-transmission, can be provided in the hybrid drive train according to the invention. Preferably, at least one torsional vibration damper can be used in the proposed hybrid drive train, which can preferably be arranged inside an electric motor to further save installation space. However, other arrangement options are also conceivable. Furthermore, spur gear drives, countershaft gears, planetary gears, or the like can be used as sub-transmissions in the gear transmission.

[0016] According to a further development of the invention, it can be provided that the assignment of, for example, the first electric motor to an odd-numbered gear stage of the first partial transmission can be realized, for example, directly or via a traction drive or via a planetary drive or via at least one spur gear stage or the like. In the same way, the assignment of the second electric motor to an even-numbered gear stage of the second partial transmission can also be established. However, other connection options are also conceivable.

[0017] In order to establish a switchable operative connection, for example, between the first electric motor or the first partial transmission and the motor shaft of the internal combustion engine, the first electric motor can preferably be coupled to the motor shaft of the internal combustion engine directly or via a traction drive or a planetary drive or via at least one spur gear stage. Analogously, it is also possible for the proposed hybrid drive train to establish a switchable operative connection between the second electric motor or the second partial transmission and an output shaft of the gear transmission via at least one gear stage switching element assigned to a gear stage of the second partial transmission.

[0018] Within the scope of a further development of the invention, it can also be provided that, in order to establish a switchable operative connection between the second electric machine and the output shaft of the gear transmission, the second electric machine can be connected directly or via a traction drive or via a planetary drive or via at least one spur gear stage to the output shaft of the gear transmission via a second positive switching element.

[0019] According to a further embodiment of the present invention, it can also be provided that an operative connection between the second partial transmission and a motor shaft of the internal combustion engine can be realized in that the second electric machine can be brought into operative connection directly or via a traction drive or a planetary drive or via at least one spur gear stage with the motor shaft of the internal combustion engine assigned, for example, to the two partial transmissions via the second positive switching element.

[0020] According to a further embodiment, an operative connection between the second electric machine and the motor shaft can be realized in that the second electric machine can be brought into operative connection with the motor shaft directly or via a traction drive or a planetary drive or at least one spur gear stage via a positive gear stage switching element of the second partial transmission, for example via a switching claw or the like, which is assigned, for example, to even gear stages.

[0021] Regardless of the respective designs, configurations and further developments, claw clutches are preferably used as positive-locking shift elements. Other shift elements can also be used. For example, internal or external actuating devices can be used to actuate the shift elements. For example, these can preferably be actuated electrically by actuators or the like. To actuate the shift elements, shafts of the sub-transmissions, such as side shafts, countershafts or other sub-transmission shafts, are designed to be axially displaceable in order to realize different shift positions in the sub-transmissions. Joint actuation of shift elements, in particular also of a sub-transmission, by a common actuating device can be particularly advantageous.

[0022] For example, it can also be provided that shafts assigned to a partial transmission are axially displaced synchronously via an actuating device or shift fork or the like in order to realize predetermined shift positions.

[0023] The present invention will be further explained below with reference to the drawings, which illustrate various embodiments of the hybrid drive train according to the invention. They show: Fig. 1 a schematic view of a first embodiment of the hybrid drive train as a 4-speed hybrid drive train with two side shafts and a common output shaft; Fig. 1A is a schematic view of an alternative embodiment according to Fig. 1 with an electric machine permanently connected to the combustion engine; and Fig. 2 a schematic view of a second embodiment of the hybrid drive train as a 4-speed hybrid drive train with two side shafts with associated electric motors and a common output shaft.

[0024] The figures show various embodiments of a hybrid drive train for a vehicle, in particular a motor vehicle, comprising an internal combustion engine 1 with a motor shaft 2 and a gear transmission with a first sub-transmission 3 with the odd gear stages 1st gear, 3rd gear, and a second sub-transmission 4 with the even gear stages 2nd gear, 4th gear for shifting without interruption in traction. The sub-transmissions 3, 4 are connected to an output shaft 9 of the gear transmission depending on the selected gear stage 1st gear, 2nd gear, 3rd gear, 4th gear. Depending on the embodiment, positive gear shifting elements or shifting claws KL1, KL2, KL3, KL4 are provided for shifting the respective gear stages 1st gear, 2nd gear, 3rd gear, 4th gear of the sub-transmissions 3, 4.

[0025] To dampen vibrations, a torsional vibration damper 5 is provided between the internal combustion engine 1 and the gear transmission. Furthermore, the hybrid drive train comprises a first electric machine EM1, which is assigned to the first sub-transmission 3, and a second electric machine EM2, which is assigned to the second sub-transmission 4. The electric machines EM1, EM2 can be assigned directly or indirectly to a sub-transmission shaft 10, 11 or side shaft 12, 12A, 13, 13A of the respective sub-transmission 3, 4. Furthermore, at least one energy storage device 6 and at least one control electronics unit 7 are provided, wherein the control electronics unit 7 essentially comprises control, power electronics, and sensor components. One or more speed sensors 8 are preferably provided for speed detection.

[0026] In the hybrid drive train, it is provided that at least one electric machine EM1, EM2 assigned to a sub-transmission 3, 4 can be operatively connected to the internal combustion engine 1 via at least one positive shifting element K1, K2. In this way, the required operative connections between the internal combustion engine 1 and the sub-transmissions 3, 4 or the electric machines EM1, EM2 are realized with only at least one positive shifting element, such as a dog clutch. Thus, a double clutch is no longer required, which saves installation space. Furthermore, thermal synchronization is no longer required in the hybrid drive train according to the invention due to the positive shifting elements K1, K2.

[0027] In Fig. 1 shows an example of a first embodiment of a 4-speed hybrid drive train, in which the first electric machine EM1 can be operatively connected to the motor shaft 2 and thus to the combustion engine 1 via the first shift element K1 and the second electric machine EM2 can be operatively connected to the motor shaft 2 and thus to the combustion engine 1 via the second shift element K2. The first electric machine EM1 is directly connected to the sub-transmission shaft 10 of the first sub-transmission 3, and the second electric machine EM2 is directly connected to the sub-transmission shaft 11 of the second sub-transmission 4. Fixed gears of the two sub-transmissions 3, 4 are arranged on the sub-transmission shafts 10, 11. The hybrid drive train is shown with two side shafts 12, 12A; 13, 13A for each sub-transmission 3, 4 and a common output shaft 9, which is arranged coaxially to the motor shaft 2. On the side shafts 12, 12A, 13, 13A, loose gears are provided as gear stage wheels of the two partial transmissions 3, 4.This design makes the gear transmission significantly shorter, which is particularly advantageous for front-transverse applications. The gear shift elements KL1 and KL3, or KL2 and KL4, which are jointly assigned to a sub-transmission 3, 4, can each be actuated via a common actuator, indicated by a dashed line.

[0028] Out of Fig. 1 shows that the common actuating device is assigned to both a shift fork of the gear shifting element KL1 for shifting the first gear 1.Gg and a shift fork of the gear shifting element KL3 for shifting the third gear 3.Gg. Accordingly, a movement to the left in the drawing plane engages the first gear 1.Gg and, at the same time, the shift fork of the gear shifting element KL3 for shifting the third gear 3.Gg is shifted further to the left without any shifting effect. If the common actuating device is shifted to the right in the drawing plane, the third gear 3.Gg is shifted and, at the same time, the shift fork of the gear shifting element KL1 is shifted further to the right without any shifting effect.

[0029] Furthermore, Fig. 1 that the common actuating device is assigned to both a shift fork of the gear shifting element KL2 for shifting the second gear 2.Gg and a shift fork of the gear shifting element KL4 for the fourth gear 4.Gg. Accordingly, a movement to the left in the drawing plane engages the second gear 2.Gg and, at the same time, the shift fork of the gear shifting element KL4 for the fourth gear 4.Gg is shifted further to the left without any shifting effect. If the common actuating device is shifted to the right in the drawing plane, the fourth gear 4.Gg is shifted and, at the same time, the shift fork of the gear shifting element KL2 is shifted further to the right without any shifting effect.

[0030] In this first embodiment, the first electric motor EM1 is designed for starting off and can be decoupled during driving in the even gears 2nd and 4th gears. The second electric motor EM2 can be decoupled during driving in the odd gears 1st and 3rd gears. The first gear 1st gear can preferably be designed for the combustion engine-driven range of significantly less than 50 km / h. The second gear 2nd gear can preferably be designed for the combustion engine-driven range of less than 50 km / h. The third gear 3rd gear can preferably be designed for the combustion engine-driven range of maximum speed. The fourth gear 4th gear can preferably be designed for the combustion engine-driven range of an overdrive gear.

[0031] According to Fig. 1A is an alternative version of the 4-speed hybrid powertrain according to Fig. 1, in which, in contrast to the one in Fig. In the embodiment shown in Figure 1, the second electric motor EM2 is constantly operatively connected to the internal combustion engine 1, in which the motor shaft 2 is firmly connected to the partial transmission shaft 11 of the second partial transmission 4. This results in a further reduction in construction costs due to the elimination of the second switching element K2.

[0032] In Fig. Figure 2 shows a second embodiment variant as a 4-speed hybrid drivetrain with a side shaft 12, 13 for each sub-transmission 3, 4 and a common sub-transmission shaft 10. Furthermore, the motor shaft 2 is assigned to both sub-transmissions 3, 4 via a spur gear stage. The two electric motors EM1, EM2 are each connected to the side shafts 12, 13. In this embodiment variant, the gear transmission is even shorter, which is particularly advantageous for front-transverse use. The shift forks of the first shift element K1 and the second shift element K2 can be operated via a common actuator, which is indicated by a dashed line.

[0033] Out of Fig.2 it can be seen that the common actuating device is assigned to both a shift fork of the first shifting element K1 and a shift fork of the second shifting element K2. Accordingly, the first and second shifting elements K1, K2, which are assigned to different sub-transmissions 3, 4, are shifted using the common actuating device. Accordingly, a movement to the left in the drawing plane shifts the first shifting element K1 and, at the same time, the shift fork of the second shifting element K2 is shifted further to the left without any shifting effect. If the common actuating device is shifted to the right in the drawing plane, the second shifting element K2 is shifted and, at the same time, the shift fork of the first shifting element K1 is shifted further to the right without any shifting effect.

[0034] Overall, the proposed hybrid powertrain results in an improvement in efficiency due to the elimination of hydraulic components, such as pumps and friction shift elements, and due to the realization of gear steps via claws without the use of energy, resulting in an advantageous approximation of an ideal CVT transmission with a high number of gears and gear ratio spread. Reference symbol 1 combustion engine 2 Motor shaft 3 first partial transmission 4 second partial transmission 5 torsional vibration dampers 6 energy storage 7 Control electronics 8 Speed ​​sensor 9 Output shaft 10 Partial transmission shaft of the first partial transmission 11 Partial transmission shaft of the second partial transmission 12,12A Side shaft of the first partial gearbox 13,13A Side shaft of the second partial gearbox EM1 first electric machine EM2 second electric machine K1 first positive-locking switching element or claw clutch K2 second positive-locking switching element or claw clutch KL1 Gear shift element for the first gear KL2 Gear shift element for the second gear KL3 Gear shift element for the third gear KL4 Gear shift element for the fourth gear KL13 Gear shift element for the first and third gear KL24 Gear shift element for the second and fourth gear 1. Gg first gear 2. Gg second gear 3. Gg third gear 4. Gg fourth gear

Claims

[1] Hybrid drive train for a vehicle with at least one internal combustion engine (1), with at least one gear transmission with at least two partial transmissions (3, 4) for shifting without interruption of traction, each having at least one shiftable gear stage, with a plurality of electric machines (EM1, EM2), wherein at least two partial transmissions (3, 4) are each assigned at least one electric machine (EM1, EM2) which are operatively connected or can be brought into operative connection with the internal combustion engine (1), and with at least one energy store (6) and with at least one control electronics (7) for controlling the electric machines (EM1, EM2), wherein at least one electric machine (EM1, EM2) assigned to a partial transmission (3, 4) can be brought into operative connection with the internal combustion engine (1) via at least one positive shifting element (K1, K2), wherein for shifting the respective gear stages of the partial transmissions (3, 4), positive gear stage shifting elements (KL1, KL2, KL3,KL4) are provided, and wherein switching elements (K1, K2, KL1, KL2, KL3, KL4) assigned to the partial transmissions (3, 4) can be switched by means of a common actuating device, , characterized by that for actuating the switching elements (K1, K2, KL1, KL2, KL3, KL4), partial transmission shafts (10, 11) and / or side shafts (12, 12A, 13, 13A) of the partial transmissions (3, 4) are designed to be axially displaceable. [2] Hybrid powertrain according to claim 1, characterized by that claw clutches are provided as positive switching elements (K1, K2, KL1, KL2, KL3, KL4). [3] Hybrid drive train according to one of the preceding claims, characterized by that the switching elements (K1, K2, KL1, KL2, KL3, KL4) can be actuated via an external actuating device. [4] Hybrid drive train according to one of the preceding claims, characterized bythat the first electric machine (EM1) assigned to the first partial transmission (3) can be brought into operative connection with the internal combustion engine (1) via at least one positive switching element (K1) and that at least one second electric machine (EM2) assigned to the second partial transmission (4) is constantly in operative connection with the internal combustion engine (1). [5] Hybrid drive train according to claims 1 to 3, characterized by that a first electric machine (EM1) assigned to the first partial transmission (3) can be brought into operative connection with the internal combustion engine (1) via at least one first positive-locking switching element (K1) and a second electric machine (EM2) assigned to the second partial transmission (4) can be brought into operative connection with the internal combustion engine (1) via at least one second positive-locking switching element (K2).

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