Hybrid powertrain

Abstract

The invention relates to a hybrid powertrain (1) having: an internal combustion engine (2) with a crankshaft (5); an electric machine (3) having a stator (6) and a rotor (7); a transmission (4), the main rotational axis (HA) of which extends in alignment with the crankshaft (5); a three-axis planetary gear set (9) arranged coaxially with the main rotational axis (HA), the planetary gear set having a first member (9.1), a second member (9.2) and a third member (9.3), wherein the third member (9.3) is non-rotatably connected or connectable to the crankshaft (5); an intermediate shaft (8) which can be connected to the first member (9.1) of the planetary gear set (9) by exactly one first gear pair (10), the intermediate shaft being arranged parallel and axially offset with respect to the main rotational axis (HA), wherein the rotor (7) of the electric machine (3) is arranged coaxially with the intermediate shaft (8) and engages or can engage non-rotatably with the intermediate shaft (8); at least one first driven shaft (11) which can engage with the second member (9.2) of the planetary gear set (9) by exactly one second gear pair (12), the first driven shaft being arranged parallel and axially offset with respect to the main rotational axis (HA) and the intermediate shaft (8).

Description

Technical field

[0001] The invention relates to a hybrid powertrain having an internal combustion engine, an electric motor and a transmission. Background art

[0002] For example, US2020 / 039342 A1 discloses a hybrid powertrain.

[0003] DE 10 2015 226 008 A1 discloses a vehicle transmission assembly having a coaxial planetary gear drive. The transmission assembly can be used in a hybrid powertrain of the same type, specifically in particular in the transmission assembly structure according to FIG. 5 in the above-mentioned document. This structure includes two three-shaft planetary gear sets both here and in all other variants. This structure is therefore relatively complex and has the disadvantage of requiring a large amount of structural space especially when viewed in the axial direction of the transmission. Summary of the invention

[0004] The object of the invention is to specify, relative to the prior art of the same type, a hybrid powertrain having an internal combustion engine, an electric motor and a transmission, which can be realized extremely compactly especially in the axial direction while functioning well.

[0005] The hybrid powertrain of the invention includes an internal combustion engine having a crankshaft and an electric motor having a stator and a rotor. A transmission is provided similarly to the aforementioned prior art, and its main rotational axis extends aligned with the crankshaft. A three-shaft planetary gear set is provided coaxially with the main rotational axis, which has a first component, a second component and a third component, as is common in a planetary gear set. The third component is non-rotatably connected to the crankshaft or preferably can be connected thereto by a disconnect clutch.

[0006] Two rotatably mounted elements being non-rotatably connected or non-rotatably engaged means that these two elements are coaxially arranged with respect to each other and are connected to each other such that they rotate at the same angular velocity.

[0007] Similarly to the prior art, the first component of the planetary gear set is engaged to an intermediate shaft by exactly one first gear pair, and the intermediate shaft is arranged parallel and axially offset with respect to the main rotational axis and is non-rotatably engaged or can be engaged to the electric motor rotor.

[0008] A gear pair in the sense of the invention here means two gears as follows, which directly mesh with each other or are engaged with each other by a chain or a toothed belt.

[0009] It is also possible that a first driven shaft is arranged parallel and axially offset with respect to both the main rotational axis and the intermediate shaft. It can be engaged to the second component of the planetary gear set by a second gear pair.

[0010] In the hybrid powertrain of the present invention, it is provided that the intermediate shaft and the first driven shaft can be engaged by exactly one third gear pair, wherein the first gear pair and the third gear pair are arranged axially offset from each other. Using exactly one gear pair between the intermediate shaft and the first driven shaft in the sense of the present invention allows the access of the electric motor, especially for driving, but in principle can also be used for energy recovery. Here, the structure is extremely simple and can be implemented very compactly, lightly and space-savingly, because it can completely dispense with the second planetary gear mechanism commonly used in the prior art in this area, but still ensures the complete functional range of the hybrid powertrain in the design of the present invention. The hybrid powertrain or its transmission of the present invention can thus be implemented extremely lightly and compactly, especially in terms of its axial extension dimension.

[0011] The term "axial" relates here to the main rotational axis, which coincides with the rotational axis of the crankshaft. Thus, the "axial direction" denotes the direction of the main rotational axis.

[0012] Two rotatably mounted parts being coaxially arranged means that the rotational axes of these two parts are the same.

[0013] Another extremely advantageous design of the hybrid powertrain of the present invention also provides for a locking element by means of which the planetary gear set can be locked so that its transmission ratio cannot be changed. Additionally, a brake switching element is provided by means of which the first component of the planetary gear set can be non-rotatably connected to the transmission housing.

[0014] According to an advantageous design, the rotor that is engaged or can be engaged with the intermediate shaft is non-rotatably connected to the intermediate shaft, so that structural space and components can also be saved at this location.

[0015] An advantageous improvement of the hybrid powertrain of the present invention provides that each gear pair includes at least one switchable moving gear, which can be connected to its respective shaft by a switching element. Here, the first gear pair can include a first fixed gear non-rotatably connected to the first component of the planetary gear set and a switchable first moving gear coaxially arranged with respect to the intermediate shaft. The second gear pair can include a fixed gear non-rotatably connected to the second component of the planetary gear set and a switchable second moving gear coaxially arranged with respect to at least one first driven shaft. The third gear pair can now especially include two switchable moving gears, namely, a third moving gear coaxially arranged with the intermediate shaft and the second moving gear of the second gear pair, and the second moving gear is correspondingly used as a component of the second and third gear pairs to save structural space and components.

[0016] Another very advantageous design of the hybrid powertrain according to the invention also provides that a first driven gear is provided which is non-rotatably connected to the first driven shaft and is arranged in the same gear plane together with a first gear pair which engages the intermediate shaft with a first component of the planetary gear set. This contributes to a particularly axially compact construction of the transmission of the hybrid powertrain.

[0017] The "gear plane" means a plane arranged perpendicular to the main axis of rotation and intersecting at least one gear which is rotatable relative to the main axis of rotation or relative to an axis arranged parallel to the main axis of rotation. When two or more gears are arranged in the same gear plane, this means that the gears intersect a common plane arranged perpendicular to the main axis of rotation.

[0018] Another very advantageous design of the hybrid powertrain according to the invention also provides for another second driven shaft which is arranged parallel and axially offset relative to the main axis of rotation, the intermediate shaft and the first driven shaft. A fourth driven gear arranged coaxially with the second driven shaft forms a fourth gear pair together with a fixed gear, where the fixed gear can in principle be an existing fixed gear, such as the fixed gear in the second gear pair, or a fourth fixed gear mounted on the same shaft, which has the advantage of a higher variability in the selection of the transmission ratio.

[0019] Here, according to an advantageous design of the concept, it can also be provided that another driven gear is provided which is non-rotatably connected to the second driven shaft. It can also be arranged in the same gear plane together with the first driven gear and the first gear pair according to a very advantageous design of the hybrid powertrain according to the invention. Thus, there will be two driven gears and the first gear pair in this gear plane. For its corresponding arrangement, the angle at which the components are arranged relative to the main axis of rotation should simply be changed accordingly in order to smoothly arrange all the components in one gear plane and thus allow a very compact construction in the axial direction.

[0020] When using the fourth fixed gear in the fourth gear pair instead of additionally using the second fixed gear, according to a very advantageous refinement, it can be provided that the fourth fixed gear is arranged in the same gear plane together with a switching element for connecting the second driven gear to the first driven shaft, and the second fixed gear is arranged in an axially adjacent gear plane together with a switching element for connecting the fourth driven gear to the second driven shaft. By arranging these two fixed gears side by side in the plane of the switching element for connecting the second driven gear to the first driven shaft or for connecting the fourth driven gear to the second driven shaft on the one hand, it is possible to arrange two of the fixed gears, namely the second and the fourth fixed gears, without additional axial structural space. That is, thus, compared to the possible sharing of the second fixed gear in principle, the structure is not increased, but the advantage of further adjustable transmission ratios is obtained.

[0021] Most of the switching elements in the transmission of the hybrid powertrain according to the invention can hereby be designed as simple dog clutches, since synchronization by means of the electric machine can be achieved to a large extent. The separating clutch and the locking element are designed as friction-locked clutches, in particular diaphragm clutches, according to an advantageous design of the invention. In addition, the switching element for connecting the second driving gear used in the second and third gear pairs to the first driven shaft is designed as a friction-locked clutch and is also designed here in particular as a diaphragm clutch. This is extremely advantageous for the only gearshift for which synchronization by means of the electric machine cannot be achieved or can only be achieved with difficulty. All other switching elements for connecting the respective driving gears to their corresponding shafts and the switching elements for braking / locking the components of the planetary gear carrier with respect to the transmission housing can be designed as simple, efficient and accordingly inexpensive dog clutches as already described, which transmit torque in a form-fitting manner after synchronization by means of the electric machine and without their own synchronization mechanism in the dog clutch.

[0022] According to another very advantageous design of the hybrid powertrain according to the invention, the braking switching element, i.e. the switching element for braking the first component of the planetary gear set with respect to the transmission housing and the switching element for connecting the first driving gear to the intermediate shaft, are arranged adjacent to one another. They can preferably be combined into a double switching element, namely a form-fitting double switching element. Description of the Drawings

[0023] Furthermore, other advantageous designs and improvements of the hybrid powertrain according to the invention result from the embodiments described in detail below with reference to the drawings, wherein:

[0024] Figure 1 A schematic diagram showing a possible embodiment of the hybrid powertrain according to the invention;

[0025] Figure 2 showing according to Figure 1 a shift table / gear position diagram of the hybrid powertrain. Detailed Description of the Embodiment

[0026] In Figure 1Fig. shows a schematic view of a hybrid powertrain 1, which includes an internal combustion engine 2, an electric motor 3 and a transmission 4. The internal combustion engine 2 drives a crankshaft marked with 5 during operation, and the crankshaft can be connected to the transmission 4 through a disengaging clutch K0. The crankshaft 5 is arranged to be aligned with the main rotational axis HA of the transmission 4. The disengaging clutch K0 is designed as a friction-locked clutch, preferably a diaphragm clutch. The electric motor 3 includes a stator 6 and a rotor 7. A three-axis planetary gear set 9 is provided coaxially with the main rotational axis HA, which includes a first component 9.1 and here is the sun gear, a second component 9.2 and here is the planetary gear carrier, and a third component 9.3 and here is the ring gear. The third component 9.3 can be connected to the crankshaft 5 of the internal combustion engine 2 through the disengaging clutch K0.

[0027] The intermediate shaft 8 can be engaged with the first component 9.1, i.e., the sun gear of the planetary gear set 9, through exactly one first gear pair 10. The intermediate shaft 8 is arranged parallel to and axially offset from the main rotational axis HA, and is engaged or connected to the rotor 7 of the electric motor 2 in a non-rotatable manner. Here, a connectable structure achieved through an optional another clutch can also be envisaged, but this is not shown in the figure.

[0028] At least one first driven shaft 11, which is also arranged parallel to and axially offset from the main rotational axis HA and the intermediate shaft 8, is connected to the second component 9.2, i.e., the planetary gear carrier of the planetary gear set 9, through exactly one second gear pair 12. In order to now achieve the structure of the hybrid powertrain 1 as compactly as possible, the intermediate shaft 8 and the first driven shaft 11 can be engaged through exactly one third gear pair 13. The first gear pair 10 and the third gear pair 13 are arranged axially offset from each other in the axial direction of the main rotational axis HA.

[0029] The transmission 4 also has another fourth gear pair 14, through which a second driven shaft 15 is connected. The second driven shaft 15 is arranged parallel to and axially offset from the main rotational axis HA, the intermediate shaft 8 and the first drive shaft 11. Through the fourth gear pair 14, the second drive shaft 15 can be connected to the planetary gear carrier, which is the second component 9.2 of the planetary gear set 9, through a switching element SA as required. The first driven shaft 11 and the second driven shaft 15 are respectively meshed with a gear 19 of the axle drive 18 through a driven gear, i.e., the first driven gear 16 and the second driven gear 17. Among them, the axle drive 18 is symbolically shown as an axle drive 18 located behind the shown plane by a circle in the area of the gear 19. The first driven gear is connected to the first driven shaft 11 in a non-rotatable manner, and the second driven gear 17 is connected to the second driven shaft 15 in a non-rotatable manner.

[0030] The transmission 4 is thus divided into two sub-transmissions 4A, 4B, which each include their own output shafts 15, 11. However, both ultimately drive the axle drive mechanism 18.

[0031] The hybrid powertrain 1 or its transmission 4 is now characterized in that the components framed by the double-dashed line, namely the first gear pair 10 and the first driven gear 16 connected to the first output shaft 11 and the second driven gear 17 connected to the second output shaft 15, are located in a single gear plane. This can be achieved in such a way that, for example, the first gear pair 10 is inclined backwards from the illustrated plane and the two driven gears 16, 17 are inclined forwards from the illustrated plane, so that they are located in a single gear plane.

[0032] The first gear pair 10 is designed such that it includes a first fixed gear 20 non-rotatably connected to a first component 9.1, namely the sun gear of the planetary gear set 9, and a first moving gear 21 coaxially arranged with respect to the intermediate shaft 8 and switchable by a switching element S0. The second gear pair 12 includes a second fixed gear 22 non-rotatably connected to a second component 9.2, namely the planetary carrier of the planetary gear set 9, and a moving gear 23 coaxially arranged with respect to the first output shaft 11 and switchable by a switching element SB, i.e., connectable to the first output shaft 11 as required. The third gear pair 13 also includes a switchable second moving gear 23 and also includes a switchable third moving gear 24 coaxially arranged with respect to the intermediate shaft 8. A switching element SE is assigned to the third moving gear 24 between the intermediate shaft 8 and the third moving gear 24. The fourth gear pair 14 includes a fourth moving gear 25 that can be switched by the switching element SA mentioned above and can be connected to the second output shaft 15 as required. The fourth gear pair also includes a fourth fixed gear 26. The fourth moving gear 25 can not only form a fourth gear pair with the fourth fixed gear 26 shown here, but in principle can also form a fourth gear pair with the second fixed gear 22 of the second gear pair 12. However, this would unnecessarily limit the possibilities when changing the transmission ratio. Since the two switching elements SA, SB already require structural space, the arrangement shown as Figure 1 can thus also be achieved with two fixed gears 22, 26 without taking up additional structural space, provided that the second fixed gear 22 is arranged in a gear plane together with the switching element SA and the fourth fixed gear 26 is arranged in an axially adjacent gear plane together with the switching element SB.

[0033] In the transmission 4 structure shown here Figure 1 also includes a locking switching element K1 by means of which the second and third components 9.2, 9.3, namely the planetary carrier and the ring gear of the planetary gear set 9, can be connected to each other. A braking switching element B0 is also provided, and the first component 9.1, namely the sun gear of the planetary gear set 9, can be braked relative toFigure 1 The shown transmission housing 27 is brought to a standstill.

[0034] This structure can now be realized extremely compactly. At this time, it is such that the braking switching element B0 is arranged adjacent to the switching element S0, so that they can preferably be combined into a double switching element.

[0035] As can be seen schematically from Figure 1 the illustration, at this time all the switching elements S0, SE, SA and the braking switching element B0 can be designed as positive switching elements. If it is operated, it can always be synchronized by the motor 3, so a simple, efficient and as wear-free as possible structure in the form of a positive switching element is ideal here. The switching element SB between the second driving gear 23 and the first driven shaft 11 should be designed as a friction-locking switching element, especially a diaphragm clutch, because synchronization by means of the motor 3 cannot be achieved when switching from the sub-transmission 4A to the sub-transmission 4B by engaging the switching element SB. The separating clutch K0 and the blocking switching element K1 are also designed as friction-locking switching elements, preferably diaphragm clutches.

[0036] Now, the respective gears are obtained according to Figure 2 the switching table in the table.

[0037] In Figure 2 the gear marked with A, as obtained from Figure 2 the switching table, the two switching elements SA and S0 are engaged and all other switching elements are disengaged. Therefore, gear A is the gear in which the motor 3 is connected to the second driven shaft 15 or its second driven gear 17. Thus, an electric start can be achieved. Then, in order to switch to the true first gear, it is specified to brake the first driving gear 21 with respect to the transmission housing 27 by means of the switching element B0. The motor 3 can then be unloaded and the clutch element S0 is disengaged accordingly. By means of the motor, the switching element SE can be synchronized and then engaged to obtain the first gear state shown in the switching table.

[0038] Now, in gear 2 there are two different gears, which ultimately result in the same transmission ratio. One is the gear marked with 2, and the other is the gear marked with 2*. Here, in addition to locking the planetary gear set 9 and engaging the clutch SA so as to output through the second driven shaft 15, the switching element SE is also engaged, and in another case, the switching element S0 is engaged instead of the switching element SE. Therefore, in the case of gear 2*, the drive is strengthened by the internal combustion engine 2, and in the case of gear 2, the drive is by the electric motor 3. Correspondingly, when switching from the first gear to the second gear, the internal combustion engine 2 is unloaded and the braking switching element P0 is disengaged, and the locking element 1 is synchronized and engaged. If it is to continue switching from gear 2 to gear 2*, the electric motor 3 is unloaded, the switching element SE is disengaged accordingly, and the switching element S0 is switched on, synchronized and engaged by the electric motor 3. Now, it is possible to drive preferably by the internal combustion engine 2 in this gear 2*, as was correspondingly mainly by the electric motor 3 in gear 2 before. The selection of gears 2 and 2* is based on the current driving strategy here.

[0039] It is possible to shift gears from both gear 2 and gear 2* to gear 3. When shifting from gear 2, the internal combustion engine is unloaded, the locking element is disengaged, and the switching element S0 is synchronized and engaged. When shifting from gear 2* to gear 3, this is done by the electric motor, then the locking element is disengaged accordingly, and the switching element SE is synchronized and engaged. Then there is a gear called B between the third gear and the fourth gear. Here, it is continuously and synchronously electrically synchronized to the actual fourth gear, i.e., the fourth gear, without traction interruption, by switching from the sub-transmission 4A to the sub-transmission 4B. For this purpose, the switching element SA is disengaged, and the switching element SB is engaged accordingly, so as to then shift gears further for a traction-interruption-free upshift to the fourth gear, i.e., just as when shifting from gear A to gear 1 as described above, but now through the first driven shaft 11 in the sub-transmission 4B, which drives the subsequent axle drive 18 by means of its first driven gear 16, just as the second driven shaft 15 together with its second driven gear 17. Therefore, in the sub-transmission 4B, the gears 5, 5* and 6 are repeated in a manner similar to the gears 2, 2* and 3 of this sub-transmission 4A.

[0040] It can also be like this, that is, the structure in which the disengaging clutch K0 hitherto associated with the engagement is driven by both the internal combustion engine 2 and the electric motor 3 has a pure electric gear. For this purpose, the disengaging clutch K0 is disengaged accordingly and the internal combustion engine 2 is, for example, switched off or even not running. The gear 3 now forms the first electric gear, whereupon the shaft coinciding with the main axis HA is driven by the electric motor 3 via the intermediate shaft, the switching element SE, the driving gear 24 and the second gear pair 12, and is the second driven shaft 15 with respect to the fourth gear pair and the engaged switching element SA. In the case of the second electric gear, the gear 2* is formed, whereupon the switching element SE is disengaged and the planetary gear set is locked accordingly in order to drive the shaft coinciding with the main rotational axis HA via the planetary gear set 9, and thereby also drive the second driven shaft 15 accordingly. Two further electric gears are then designed similarly in the sub-transmission 4B, that is, the gear 6 as the third electric gear and the gear 5* as the fourth electric gear.

Claims

1. A hybrid powertrain (1), comprising: An internal combustion engine (2) with a crankshaft (5); An electric machine (3) having a stator (6) and a rotor (7); A transmission (4), the main rotational axis (HA) of which extends in alignment with the crankshaft (5); A three - shaft planetary gear set (9) coaxially arranged with the main rotational axis (HA), the planetary gear set having a first member (9.1), a second member (9.2), and a third member (9.3), wherein the third member (9.3) is non - rotatably connected or connectable to the crankshaft (5); An intermediate shaft (8) that can be connected to the first member (9.1) of the planetary gear set (9) through exactly one first gear pair (10), the intermediate shaft being arranged parallel and axially offset with respect to the main rotational axis (HA), wherein the rotor (7) of the electric machine (3) is coaxially arranged with respect to the intermediate shaft (8) and non - rotatably engages or can engage with the intermediate shaft (8), and wherein the first gear pair (10) includes exactly two gears (20; 21); At least one first driven shaft (11) that can engage with the second member (9.2) of the planetary gear set (9) through exactly one second gear pair (12), the first driven shaft being arranged parallel and axially offset with respect to the main rotational axis (HA) and the intermediate shaft (8), and wherein the second gear pair (12) includes exactly two gears (22; 23), Characterized in that, The intermediate shaft (8) and the first driven shaft (11) can engage through exactly one third gear pair (13), wherein the first gear pair (10) and the third gear pair (13) are arranged axially offset from each other, and wherein the third gear pair (13) includes exactly two gears (23; 24), A locking switching element (K1) for locking the planetary gear set (9) and a braking switching element (B0) for non - rotatably connecting the first member (9.1) to the transmission housing (27) are provided.

2. The hybrid powertrain (1) according to claim 1, characterized in that, The rotor (7) is non - rotatably connected to the intermediate shaft (8).

3. The hybrid powertrain (1) according to claim 1 or 2, characterized in that, The first gear pair (10) includes a first fixed gear (20) non - rotatably connected to the first member (9.1) and a switchable first moving gear (21) coaxially arranged with the intermediate shaft (8).

4. The hybrid powertrain (1) according to claim 1 or 2, characterized in that, The second gear pair (12) includes a second fixed gear (22) non - rotatably connected to the second member (9.2) and a switchable second moving gear (23) coaxially arranged with the at least one first driven shaft (11).

5. The hybrid powertrain (1) according to claim 4, characterized in that, The third gear pair (13) includes a switchable third moving gear (24) coaxially arranged with the intermediate shaft (8) and a switchable second moving gear (23) coaxially arranged with the driven shaft (11).

6. The hybrid powertrain (1) according to claim 1 or 2, characterized in that, A first driven gear (16) non - rotatably connected to the at least one first driven shaft (11) is provided, and the first driven gear is arranged in a common gear plane with the first gear pair (10).

7. The hybrid powertrain (1) according to claim 6, characterized in that, There is also a second driven shaft (15) arranged parallel to and with an axial offset from the main rotational axis (HA), the intermediate shaft (8), and the first driven shaft (11), wherein a switchable fourth driving gear (25) arranged coaxially with the second driven shaft (15) meshes with a second fixed gear (22) or a fourth fixed gear (26) to form a fourth gear pair (14), and the fourth fixed gear and the second fixed gear (22) are arranged on the same shaft.

8. The hybrid powertrain (1) according to claim 7, characterized in that, There is another driven gear (17) connected to the second driven shaft (15) in a non-rotatable manner, and this other driven gear is arranged in a gear plane shared with the first driven gear (16) and the first gear pair (10).

9. The hybrid powertrain (1) according to claim 7, having a fourth fixed gear (26), characterized in that, The fourth fixed gear (26) and a switching element (SB) for connecting the second driving gear (23) to the first driven shaft (11) are arranged in an axial gear plane, and the second fixed gear (22) and a switching element (SA) for connecting the fourth driving gear (25) to the second driven shaft (15) are arranged in an axially adjacent gear plane.

10. The hybrid powertrain (1) according to claim 4, characterized in that, There is a frictionally engaged switching element (SB) by means of which the second driving gear (23) can be connected to the first driven shaft (11) in a non-rotatable manner, wherein other switching elements designed to switch other driving gears (21, 24, 25) and the braking switching element (B0) are all designed as form-locking clutches.

11. The hybrid powertrain (1) according to claim 3, characterized in that, The braking switching element (B0) and a switching element (S0) for connecting the first driving gear (21) to the intermediate shaft (8) are arranged adjacent to each other.

12. The hybrid powertrain (1) according to claim 11, characterized in that, The braking switching element (B0) and the switching element (S0) for connecting the first driving gear (21) to the intermediate shaft (8) are combined into a double switching element.

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