Hybrid drive arrangement for a motor vehicle

Abstract

Hybrid drive arrangement for a motor vehicle, comprising: - an input shaft (1) connectable to an internal combustion engine and an output shaft (2) connectable to a drive train; - an electric machine (10) having a rotor (12) and a stator (11) rigidly connected to a gearbox housing and capable of operation in both motor and generator modes, its rotor (12) being coupled to the input shaft (1) via a first coupling (41); - a first planetary gear set (100) whose sun gear (110) is connected to the rotor (12) of the electric machine (10), whose hub (120) is connected to the output shaft and whose ring gear (130) is coupled to the gearbox housing via a first brake (51); - a second planetary gear set (200) whose sun gear (210) is coupled to the sun gear (110) of the first planetary gear set (100).whose bridge (220) is connected to the input shaft (1) and whose ring gear (230) is coupled to the bridge (120) of the first planetary gear set (100), wherein one of the couplings between the first planetary gear set (100) and the second planetary gear set (200) can be switched via a second clutch (42), characterized in that the input shaft has a first freewheel (61) by which it can be fixed to the gearbox housing.

Description

The invention relates to a hybrid drive arrangement for a motor vehicle, comprisingan input shaft (1) connectable to an internal combustion engine and an output shaft (2) connectable to an output train,an electric machine (10) which has a rotor (12) and a stator (11) which is fixedly connected to a transmission housing and can be operated both in motor operation and in generator operation, its rotor (12) being coupled to the input shaft (1) via a first clutch (41),a first planetary set (100), the sun (110) of which is connected to the rotor (12) of the electric machine (10), the web (120) of which is connected to the output shaft and the ring gear (130) of which is coupled to the transmission housing via a first brake (51),a second planetary set (200), the sun (210) of which is coupled to the sun (110) of the first planetary set (100), the planet carrier (220) of which is connected to the input shaft (1) and the ring gear (230) of which is coupled to the planet carrier (120) of the first planetary set (100),wherein one of the couplings between the first planetary set (100) and the second planetary set (200) is switchable via a second clutch (42).Such a hybrid drive arrangement is known from DE 11 2005 002 846 T5.DE 10 2010 007 329 A1 discloses a hybrid drive arrangement having an electric machine and two planetary gear sets, the input shaft of which is connected to an internal combustion engine via a hydraulic torque converter. The rotor of the electric machine, the stator of which is arranged fixed to the housing, is connected fixed to the sun of the first planetary set. This is also connected to the input shaft via a first clutch. Therefore, the rotor of the electric machine is coupled to the input shaft via the first clutch. The carrier of the first planetary set is connected to an output shaft of the arrangement, which can be connected to the output of the motor vehicle, which typically comprises in particular a differential and a driven axle. The ring gear of the first planetary gear set can be fixed selectively in the direction of rotation to the transmission housing via a switchable freewheel. The sun of the second planetary gear set is coupled to the transmission housing via a brake, i.e. can be fixed to the transmission housing. Its carrier is coupled to the input shaft via a further clutch. In addition, the carrier of the second planetary set is connected to the ring gear of the first planetary set. The ring gear of the second planetary set is connected to the carrier of the first planetary set. With this known arrangement, four forward gears, which can be operated purely by the internal combustion engine or in parallel hybrid, and a purely electric reverse gear can be realized. The four switching elements required for this are in part very complex in nature. This applies in particular to the mentioned switchable freewheel, which must be able to assume three different switching positions. This results in cost and installation space disadvantages. In addition, a tensile force interruption results in each shifting process, which can be perceived as being uncomfortable by the driver.The term "connected" is used herein in the sense of a solid connection. In contrast, the term "coupled" in the context of the present description includes both fixed and switchable connections. If the latter case is specifically meant, the corresponding shifting element, in particular a brake or a clutch, is generally explicitly specified. If, however, the former case is specifically meant, the use of the term "coupled" is generally dispensed with in favor of the more specific term "connected". The use of the term "coupled" without specifying a specific switching element thus indicates the intended inclusion of both cases. This distinction is made solely for the sake of better intelligibility and in particular for the sake of clarity, where the provision of a switchable connection instead of a fixed connection which is generally easier to implement is absolutely necessary. The above definition of the term "connected" should therefore in no way be interpreted as so narrow that clutches inserted arbitrarily for bypass purposes lead out from its word sense.From the generic DE 11 2005 002 846 T5 mentioned at the beginning, a hybrid drive arrangement with two electric machines that can be operated both by motor and by generator and two planetary gear sets is known, with which a plurality of operating modes can be realized. However, practice shows that such a high number of operating modes (up to 16) is not necessary for safe, energy-efficient and comfortable vehicle operation. On the other hand, in the motor vehicle industry, there is a notoric cost pressure and lack of installation space.It is the object of the present invention to provide an improved hybrid drive structure in which a number of operating modes that is suitable for practical application can be realized in a more cost-effective and space-effective manner.This object is achieved in conjunction with the features of the preamble of claim 1 in that the input shaft has a first freewheel, by means of which it can be fixed to the transmission housing.By virtue of the ability to fix the input shaft to the transmission housing according to the invention by means of the first freewheel, it is possible to support a torque counter to the running direction of the internal combustion engine. This expansion results in the possibility, which is cost-effective and space-effective, of a second purely electric operating mode, i.e. a second electric gear, which is realized when the internal combustion engine is stationary and the second clutch is closed, with the shift elements otherwise open. For this purpose, in particular, no second electric machine is required.Two variants are conceivable, namely a first variant in which the carrier of the first planetary set is coupled via the second clutch to the ring gear of the second planetary set, and a second variant in which the sun of the first planetary set is coupled via the second clutch to the sun of the second planetary set. Unless one of the two variants is expressly emphasized, the following description refers to both variants.With the hybrid drive arrangement according to the invention, three forward gears, a continuously variable driving range and a purely electric operating mode can be realized. The continuously variable driving range is realized by a power-split operation of the arrangement; the forward gears can be operated purely by the internal combustion engine or in parallel hybrid. In a further shift position, the internal combustion engine can be started solely by the electric machine, without a separate starter being required.In a preferred embodiment of the invention, it is provided that the rotor of the electric machine is coupled to the housing via a second brake. An additional, fourth gear is thereby realized. The invention will be described below with reference to this preferred embodiment with four gears. The particular features which result from the aforementioned second brake are each pointed out at a suitable point; moreover, the following description also applies to embodiments according to the invention without a second brake.To start the internal combustion engine by means of an electric machine, only the first clutch is closed, while the other shift elements are open. A direct torque flow occurs between the rotor of the electric machine and the input shaft, which is connected to the internal combustion engine in the installed state in the motor vehicle. The rotor and the input shaft thus rotate at the same speed. In the first variant of the invention, it follows that the sun and the planet carrier of the second planetary set are driven at the same rotational speed, so that the second planetary set rotates as a block due to the opened second clutch. In the first planetary set, the sun connected to the rotor is also driven at the same speed. However, the carrier and ring gear run freely due to the opened first brake and opened second clutch, so that no torque is transmitted to the output shaft. The torque of the electric machine is therefore used solely for towing the internal combustion engine. In the second variant of the invention, the sun of the first planetary gear set and the carrier of the second planetary gear set are driven at the same speed, wherein here too no torque is transmitted to the output shaft due to the opened first brake and opened second clutch. Thus, here too, the entire torque of the electric machine is used for towing the internal combustion engine.For purely electric driving, the first brake alone is closed, while the other shift elements are open. Due to the opened first clutch and the opened second clutch, the input shaft, i.e. the internal combustion engine in the installed state in the motor vehicle, is completely decoupled from the output. The second planetary gear set is also ineffective in this switching state. However, the first planetary set acts as a pure transmission stage between the rotor of the electric machine and the output shaft because of its ring gear held by means of the closed first brake. Depending on the direction of rotation of the electric machine, it is thus possible to drive electrically both forwards and backwards with the same transmission ratio and the same torque.A first forward gear is realized by a closed first brake and a closed first clutch with the shift elements otherwise disengaged. Due to the closed first clutch, the rotor of the electric machine and the input shaft, i.e. the internal combustion engine in the installed state, are firmly coupled to one another and rotate at the same speed. In purely internal combustion engine operation, the rotor of the electric machine is dragged along; in parallel hybrid operation, torque can be fed in from both units. The same applies--in the case of a negative torque sign--to the recuperation mode. In the first variant of the invention, the planet carrier and the sun of the second planetary gear set are driven at the same speed, so that the latter rotates as a block and is ineffective due to the opened second clutch. The combined torque of the units is rather fed in via the sun of the first planetary set, which acts as a pure transmission stage because of the closed first brake and the ring gear defined as a result thereof. The latter also applies to the second variant of the invention, wherein, however, losses due to internal friction must be expected here because of the different rotational speeds of the driven shafts of the second planetary set, namely its carrier and its ring gear.A second gear is realized by a closed first brake and a closed second clutch with the shifting elements otherwise open. In this case, the torque of the internal combustion engine is fed in via the carrier and the torque of the electric machine is fed in via the sun of the second planetary set. The combined torque is conducted to the output shaft via the carrier of the first planetary set, which acts as a pure transmission stage because of its fixed ring gear and whose sun is driven at the rotational speed of the rotor of the electric machine. This applies to both variants of the invention.By opening the first brake, a transition to the continuously variable, power-split operation can be realized. This is preferably effected at engine torques in which no holding torque is applied to the first brake. In this operating mode, the total transmission ratio can be continuously adjusted by suitable torque and speed control of the electric machine. As soon as the same rotational speed between the input shaft and the rotor of the electric machine is achieved, the first clutch can be closed without slipping, as a result of which, with the first and second clutch closed, a third gear is realized with the shift elements otherwise open, which third gear can be operated purely by the internal combustion engine or in parallel hybrid. The combined torque of the units, which rotate at the same speed because of the closed first clutch, is introduced into the second planetary set and conducted to the output shaft via the carrier of the first planetary set, the sun of which is driven at the same speed as the units and the ring gear of which freewheels because of the opened first brake. In principle, stepped shifting from the second to the third forward gear is also possible. The above-described transfer by means of the interposed, power-split operating phase, however, allows a more comfortable shift without interruption of the tractive force.By opening the first clutch, preferably when no torque is present here, it is possible to switch over again to the continuously variable, power-split operating mode. As the vehicle speed increases, the contribution of the electric machine decreases ever further until its rotor comes to a standstill and a purely internal combustion-engine long gear is realized. However, the electric machine must be controlled in a supporting manner or at low rotational speeds in order to compensate for speed variations. In order to avoid this, in the case of the preferred development of the invention already mentioned above, the second brake can be closed and thus the rotor can be fixed to the transmission housing. The fourth gear, which was previously implemented as a special case of continuously variable operation, thus becomes a purely internal combustion engine gear, which allows a very efficient long-distance operation at high speeds and, like the third gear described above, can be achieved without interruption of the tractive force.Since the opening and closing of the second brake is preferably carried out when the rotor is stationary, the second brake can preferably be designed as a form-locking shifting element, whereby efficiency losses due to slipping operation are avoided.As an alternative to the second brake, it can be provided that the rotor of the electric machine is coupled to the housing via a second freewheel. This maintains the high long-distance efficiency; however, the design complexity of the arrangement is reduced by the brake being omitted and the necessary actuation thereof. However, it must be accepted as a disadvantage that the electric machine can no longer be used for reverse travel. Consequently, at least one second electric machine is required, for example as a direct drive of an axle or as a wheel direct drive. This variant is therefore useful in concepts which provide a second electric machine in any case. As a rule, in such designs the maximum tractive force will be different when driving backwards than when driving forwards.Further features and advantages of the invention will become apparent from the following specific description and the drawings.The following are shown: FIG. 1 shows an embodiment of the hybrid drive arrangement according to the invention according to a first variant FIG. 2 shows an embodiment of the hybrid drive arrangement according to the invention according to a second variant FIG. 3 shows an embodiment of the hybrid drive arrangement according to the invention in a modified form of the second variant.Identical reference numerals in the figures indicate identical or analogous components.Fig. 1 shows a particularly preferred embodiment of the present invention. The arrangement, which is also to be referred to here in simplified form as a "transmission", has the input shaft 1 as the input element and the output shaft 2 as the output element. The input shaft 1 is connected to an internal combustion engine, not shown, in the installed state in the motor vehicle. The output shaft 2 is connected to the motor vehicle with an output, not shown in detail, in the installed state in the motor vehicle. This typically comprises at least one differential and at least one driven axle.The electric machine 10 is an essential component of the hybrid drive arrangement, having a stator 11 fixed to the housing and a rotor 12 mounted rotatably with respect thereto.The transmission further has two planetary sets, namely a first planetary set 100 and a second planetary set 200, each of which has a sun gear 110 or 210, a carrier 120 or 220 with a set of planetary gears 121 or 221 rotatably mounted thereon, and a ring gear 130 or 230. The components mentioned are arranged in the usual manner such that the planetary gears 121 and 221 mesh with the respective sun 110 and 210 and the respective ring gear 130 and 230.The input shaft 1 is fixedly connected to the carrier 220 of the second planetary set 200. The output shaft 2 is fixedly connected to the carrier 120 of the first planetary set 100. The rotor of the electric machine 12 is fixedly connected to the fixedly interconnected suns 110, 120 of the first and second planetary sets 100, 200.Further elements are switchably coupled to one another or to the transmission housing, not shown in more detail, via a total of four shift elements. Thus, a first clutch 41 is provided between the input shaft 1 and the rotor 12 of the electric machine 10, with which clutch a rotationally fixed connection between the two elements can be produced or released as required. Furthermore, a second clutch 42 is provided between the carrier 120 of the first planetary set 100 and the ring gear 230 of the second planetary set 200, with which clutch a rotationally fixed connection between the two elements can be produced or released as required. Furthermore, the ring gear 130 of the first planetary gear set 100 is coupled to the transmission housing via a first brake 51, i.e. can be fixed to the transmission housing as required. In the preferred embodiment shown in FIG. 1, a second brake 52 is also provided, by means of which the rotor 12 of the electric machine 10 is coupled to the housing, i.e. can be fixed to the latter as required. With regard to the functionalities of the switching elements mentioned and the operating modes which can be realized as a result, reference is made to the explanation in the above, general part of the description.In FIG. 1, a first freewheel 61 is illustrated. The freewheel 61 represents a coupling between the input shaft 1 and the transmission housing. With regard to its functionality and effect, reference is made to the above general part of the description. Not shown in FIG. 1 is the possibility, which is fundamentally present, of replacing the second brake 52 by a second freewheel. With regard to the effect of this measure, in particular the advantages and disadvantages, reference is made to the explanation in the general part of the description.FIG. 2 shows a first embodiment of the hybrid drive arrangement according to the invention in a second variant. This differs from the first variant shown in FIG. 1 merely by the arrangement of the second clutch 42; this couples the sun 201 of the second planetary set 200 shiftably to the sun 110 of the first planetary set 100, which in turn, as in the first variant, is fixedly connected to the rotor 12 of the electric machine 10. Accordingly, the coupling between the ring gear 230 of the second planetary set 200 and the carrier 120 of the first planetary set 100 is designed as a fixed connection in the second variant shown in FIG. 2. These are the only differences between the embodiments of FIGS. 1 and 2, so that reference can otherwise be made to the explanation of FIG. 1 in its entirety.FIG. 3 shows a second embodiment of the second variant of the transmission according to the invention. This differs from the first embodiment of the second variant shown in FIG. 2 only in its spatial arrangement of the individual components. Their connection to one another corresponds exactly to the first embodiment of the second variant, so that reference can be made to the explanation of FIG. 2 in its entirety accordingly. The skilled person will understand that the alternative arrangement of the electric machine 10 shown in FIG. 3 at the end of the transmission remote from the internal combustion engine is not expedient in the component interconnection according to the first variant. Accordingly, the first variant is shown only in an embodiment according to FIG. 1.Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative exemplary embodiments of the present invention. The skilled person will be given a wide range of possible variations in the light of the disclosure here. In particular, the shifting between the gears can take place both in the traction force interruption-free manner described as being preferred and in a conventional manner with traction force interruption. The skilled person will recognize that the described control during upshifting can also be used in an analogous manner for downshifting. Furthermore, it is possible to use the transmission according to the invention within the scope of a more complex hybrid concept, which comprises in particular at least one second electric machine, which can be used, for example, as a final drive of an axle that is otherwise not driven via the transmission according to the invention or as a wheel direct drive. It is of course also possible, while maintaining the interconnections of the components involved described here, to arrange them spatially differently in order to meet the installation space requirements in the respective individual case.List of reference characters1 Input shaft 2 Output shaft 10 Electric machine 11 Stator of 10 12 Rotor of 10 41 First clutch 42 Second clutch 51 First brake 52 Second brake 61 First freewheel 100 First planetary set 110 Sun of 100 120 Web of 100 121 Planets to 120 130 Ring gear of 100 200 Second planetary set 210 Sun of 200 220 Web of 200 221 Planets to 220 230 Ring gear of 200

Claims

Hybrid drive arrangement for a motor vehicle, comprising - an input shaft (1) which can be connected to an internal combustion engine and an output shaft (2) which can be connected to an output train, - an electric machine (10) which has a rotor (12) and a stator (11) which is fixedly connected to a transmission housing and can be operated both in motor and in generator operation, wherein its rotor (12) is coupled to the input shaft (1) via a first clutch (41), - a first planetary set (100), the sun (110) of which is connected to the rotor (12) of the electric machine (10), the web (120) of which is connected to the output shaft and the ring gear (130) of which is coupled to the transmission housing via a first brake (51), - a second planetary set (200), the sun (210) of which is coupled to the sun (110) of the first planetary set (100), its carrier (220) is connected to the input shaft (1) and its ring gear (230) is coupled to the carrier (120) of the first planetary set (100), wherein one of the couplings between the first planetary set (100) and the second planetary set (200) can be shifted via a second clutch (42), characterized in that the input shaft has a first freewheel (61), via which it can be fixed to the transmission housing.Hybrid drive arrangement according to Claim 1, characterized in that the carrier (120) of the first planetary set (100) is coupled via the second clutch (42) to the ring gear (230) of the second planetary set (200).Hybrid drive arrangement according to Claim 1, characterized in that the sun (110) of the first planetary set (100) is coupled to the sun (210) of the second planetary set (200) via the second clutch (42).Hybrid drive arrangement according to one of the preceding claims, characterized in that the rotor (12) of the electric machine (10) is coupled to the housing via a second brake (52).Hybrid drive arrangement according to one of the preceding claims, characterized in that the second brake (52) is designed as a positively locking shift element.Hybrid drive arrangement according to one of Claims 1 to 3, characterized in that the rotor (12) of the electric machine (10) is coupled to the housing via a second freewheel.Hybrid drive arrangement according to one of the preceding claims, characterized in that the first brake (51) is designed as a positively locking shift element.

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