Commercial vehicle with a parallel hybrid powertrain

Abstract

Commercial vehicle, comprehensive a) comprising a parallel hybrid powertrain (100), - an internal combustion engine (1), - an electric machine (2) connected to a drive shaft (4) of a vehicle transmission (3), which can be operated as a motor and as a generator and - a first coupling (5) arranged between the internal combustion engine (1) and the electric machine (2), by means of which the internal combustion engine (1) can be decoupled from the electric machine (2) and the vehicle transmission (3) in terms of drive, wherein the internal combustion engine (1) together with the electric machine (2) can be connected via the vehicle transmission (3) to at least one axle (8) for drive purposes, wherein the commercial vehicle can be driven optionally in at least one purely internal combustion engine first operating mode and one purely electric motor second operating mode; b) a control device (10) designed to switch between the at least two operating modes, wherein the control device (10) is designed to open the first clutch (5) in the purely electric motor-driven second operating mode, so that a crankshaft and a valve train of the internal combustion engine (1) are not driven by the electric machine (2); and c) a first group of auxiliary units which are mechanically driven independently of the internal combustion engine (1) in the purely electric motor second operating mode and / or are electrically driven, wherein the first group of auxiliary units includes an air compressor (11); characterized in that the electric machine (2) is permanently connected to the vehicle transmission in a rotationally fixed manner and the first group of auxiliary units is electrified.

Description

[0001] The invention relates to a commercial vehicle with a parallel hybrid drivetrain.

[0002] Parallel hybrid powertrains for commercial vehicles are known from the prior art. These powertrains consist of an internal combustion engine and an electric motor, which can be connected to at least one axle via a transmission. For example, German patent application DE 10 2014 012 397 A1 discloses a hybrid drive arrangement for a motor vehicle in which the electric motor acts on the crankshaft via a power take-off flange of the internal combustion engine, instead of being arranged axially to the crankshaft. This offers the advantage that an existing power take-off interface can be used to mount the electric motor, thus enabling a simple "hybridization" of an existing conventional powertrain and avoiding complex configuration changes.One disadvantage of this approach, however, is that to achieve a purely electric operating mode (purely electric driving), the electric motor cannot be separated from the crankshaft of the internal combustion engine, meaning that the crankshaft and valve train of the internal combustion engine are dragged along during purely electric driving. This results in a high current demand for the electric motor, as the drag torque of the internal combustion engine must be overcome in addition to the driving resistance.

[0003] Furthermore, approaches are known from the prior art in which the rotor-stator arrangement of the electric machine is arranged coaxially to the crankshaft and is rotationally fixed to it. If, in this drivetrain arrangement, the electric machine cannot be decoupled from the crankshaft of the internal combustion engine during electric driving, the aforementioned high drag losses also occur.

[0004] If, however, the electric motor is disconnected from the crankshaft drive by a clutch during purely electric driving, the auxiliary components mechanically driven by the internal combustion engine via a gear train or crankshaft drive are no longer powered and are therefore unavailable during purely electric driving. Examples of such auxiliary components are the air compressor, also known as an air compressor, for supplying a commercial vehicle's compressed air system, or a power steering pump, which are typically located on the crankcase of a commercial vehicle's internal combustion engine. Safe operation of a commercial vehicle is not possible without the proper functioning of an air compressor or power steering pump.

[0005] With regard to the state of the art relevant to a commercial vehicle with a parallel hybrid powertrain, reference is also made to US 2012 / 0 167 857 A1, WO 2012 / 000 630 A1, DE 100 57 798 A1, US 2012 / 0 266 701 A1, DE 197 48 423 A1 and DE 40 41 117 A1.

[0006] It is therefore an object of the invention to provide an improved commercial vehicle with a parallel hybrid powertrain that avoids the disadvantages of conventional technologies. In particular, the object of the invention is to provide a parallel hybrid powertrain that enables purely electric driving.

[0007] These problems are solved by a commercial vehicle with a parallel hybrid drivetrain having the features of the independent claim. Advantageous embodiments and applications of the invention are the subject of the dependent claims and are explained in more detail in the following description with partial reference to the figures.

[0008] According to the invention, a commercial vehicle is provided with a parallel hybrid drivetrain. According to general principles of the invention, the parallel hybrid drivetrain comprises an internal combustion engine, a vehicle transmission, and an electric machine, which can be operated as a motor and generator and is connected to a drive shaft of the vehicle transmission. The internal combustion engine, together with the electric machine, can be driven by at least one axle via the vehicle transmission. The axle is preferably a rear axle of the commercial vehicle. The parallel hybrid drivetrain further comprises a first clutch arranged between the internal combustion engine and the electric machine. The first clutch can be a switchable friction clutch, a torque converter clutch, or a combination thereof.

[0009] By means of the first clutch, the internal combustion engine can be decoupled from the electric machine and the vehicle transmission in terms of drive, so that a power flow between the electric machine and the vehicle transmission is possible, while at the same time no power flow between the electric machine and the internal combustion engine is possible.

[0010] Furthermore, the commercial vehicle can be driven in at least one purely combustion engine operating mode and one purely electric motor operating mode (Electric Motoring). The second operating mode thus corresponds to purely electric driving, in which the drive power is provided solely by the electric motor.

[0011] The commercial vehicle also includes a control unit designed to switch between at least two operating modes. In the purely electric motor-driven second operating mode, the control unit is further designed to open the first clutch, so that the crankshaft and valve train of the internal combustion engine are not driven by the electric motor when the latter generates a power flow to the drive shaft of the vehicle transmission.

[0012] The commercial vehicle further comprises at least one auxiliary unit, preferably several auxiliary units, which can be driven independently of the internal combustion engine in the purely electric second operating mode. This means that this at least one auxiliary unit can be driven during purely electric driving without the internal combustion engine having to be towed by the electric motor and without the need for the internal combustion engine to be fired. These auxiliary units are hereinafter referred to as the first group of auxiliary units and are, in particular, auxiliary units that are absolutely necessary for driving. Examples of such auxiliary units are the air compressor of a compressed air system of the commercial vehicle and the power steering pump, which, according to the invention, can be driven independently of the internal combustion engine during purely electric driving.To enable these auxiliary units to be driven independently of the internal combustion engine during purely electric driving, they can either be electrified, i.e., electrically driven, or mechanically driven independently of the internal combustion engine, for example, by being mechanically driven by the electric motor. If the auxiliary units of the first group are driven by a mechanical coupling with the electric motor, no separate electrification of the auxiliary units is required, so that conventionally designed auxiliary units can be used.

[0013] The commercial vehicle may include additional auxiliary units that can only be driven mechanically by the internal combustion engine. Such auxiliary units are therefore not part of the first group of auxiliary units.

[0014] A particular advantage of the commercial vehicle according to the invention is that the parallel hybrid drivetrain also enables temporary purely electric driving and maneuvering, in which the crankshaft and valve train can be mechanically decoupled from the electric motor by means of the first clutch, so that they are not dragged along during purely electric driving and drag losses are thus avoided. At the same time, at least a first group of auxiliary units is provided, which are also driven in purely electric motor operating mode and are therefore available without the need for the combustion engine to be fired and without the combustion engine being dragged along by the electric motor. This first group of auxiliary units includes the air compressor and preferably the power steering pump, so that at least the basic functions for safe driving operation are provided.

[0015] However, it is emphasized that within the scope of the invention it is of course also possible to design any further auxiliary units in such a way that they can be driven independently of the internal combustion engine even in purely electric mode and / or are electrically driven. This allows additional vehicle functions to increase comfort and / or safety, or auxiliary units for operating the vehicle and its structure (e.g., hydraulic pumps), to be made available even during purely electric driving.

[0016] The all-electric operation thus enables access to emission-free zones, such as food processing plant warehouses, for the commercial vehicle. It also allows for reduced cooling of the exhaust aftertreatment system during idling or low-load operation, as well as fuel savings through shorter activation times for the heating system.

[0017] According to a particularly preferred embodiment of the invention, a second clutch can be arranged between the electric machine and the vehicle transmission, by means of which the electric machine can be decoupled from the vehicle transmission in terms of its drive function. According to this embodiment, the control device is configured to open the second clutch to start the internal combustion engine using the electric machine, thereby interrupting the power flow from the electric machine to the vehicle transmission. According to this embodiment, the electric machine can thus function as an integrated starter-generator, by means of which the internal combustion engine can be started, thus eliminating the need for a separate conventional starter. During such a starting process, the first clutch is naturally closed, thus enabling a power flow between the electric machine and the internal combustion engine.According to this embodiment, both a crank starter-generator function and purely electric driving operation can be provided. The second clutch can be designed as a switchable friction clutch arranged between the electric motor and the vehicle transmission. The second clutch can also be designed as a torque converter clutch.

[0018] According to a preferred embodiment of this design, the air compressor can be mechanically driven by the electric motor. One possible implementation according to the invention provides that the air compressor is, for example, arranged in a conventional manner on the crankcase of the internal combustion engine and can be mechanically driven by the internal combustion engine via a gear drive and / or crank drive. Thus, the air compressor can, for example, be driven by the internal combustion engine in a conventional manner during operation of the vehicle's combustion engine. Furthermore, the air compressor can additionally be designed such that a drive shaft of the air compressor can be driven by the electric motor during purely electric driving.In this way, a conventional air compressor can be designed, with minor modifications, to be driven even when driving purely electrically, if the mechanical drive via the internal combustion engine is not available.

[0019] Alternatively, the air compressor can also be electrified, i.e., electrically driven. Similarly, the power steering pump and, if applicable, other auxiliary components of the first group can be electrically driven independently of the internal combustion engine or mechanically driven by the electric motor, in order to power them during purely electric driving.

[0020] According to an alternative preferred embodiment, the electric machine can also be permanently and rotationally fixedly connected to the vehicle transmission. In this embodiment, the auxiliary components of the first group are electrified in order to provide sufficient drive power for the auxiliary components even at low transmission speeds.

[0021] As mentioned above, it is also possible within the scope of the invention that the commercial vehicle has, in addition to the air compressor and the power steering pump, further auxiliary units that can also be driven when the internal combustion engine is switched off.

[0022] For example, the commercial vehicle may have a second group of auxiliary units, comprising an alternator, which are arranged in the area of ​​an end face of the internal combustion engine facing the front of the vehicle. These auxiliary units are preferably mechanically driven by the internal combustion engine via a belt drive.

[0023] Such an arrangement of auxiliary components is known from the prior art. Examples of such auxiliary components, besides the alternator, include a water pump or a refrigerant compressor. To increase vehicle comfort and / or vehicle safety, these auxiliary components can also be designed so that they can be driven in the second operating mode, i.e., when the internal combustion engine is switched off.

[0024] One option involves one or more auxiliary units in this group being electrified or at least capable of being electrically driven. In this option, it is possible, but not required, for these auxiliary units to also be mechanically driven by the internal combustion engine via a belt drive. The term "additionally electrically driven" means that they can be driven mechanically by the internal combustion engine when it is running and electrically when the engine is not running.

[0025] A second variant further provides that the alternator can be operated not only as a generator but also as a motor, and that the control unit is also designed to drive the auxiliary components of the second group by means of motor operation of the alternator in the purely electric motor operating mode. The drive power of the alternator in motor operation is transmitted to the other auxiliary components via the existing belt drive. It is advantageous here that a freewheel is provided on the drive pulley of the belt drive on the internal combustion engine side to prevent the crankshaft and valve train from being dragged along.

[0026] According to another variant, an alternative drive for the auxiliary units of the second group can be achieved by providing an additional shaft that can be driven by the electric machine in the second operating mode and is thereby connected to the belt drive of the second group of auxiliary units. In this case, the control device is designed to bring the additional shaft into operative connection with the electric machine in the purely electric motor-driven second operating mode, so that the additional shaft is driven by the electric machine and thus drives the auxiliary units of the second group.

[0027] For example, the auxiliary shaft can be located laterally outside the crankcase of the internal combustion engine, thus coupling the electric motor to the front belt drive. An alternative implementation of the auxiliary shaft involves it being designed as the inner shaft of a hollow crankshaft.

[0028] Similarly, one or more auxiliary components located at the rear end of the internal combustion engine can either be electrified or driven via the auxiliary shaft. The rear end of the internal combustion engine refers to the transmission-side end face of the engine.

[0029] The preferred embodiments and features of the invention described above can be combined in any way desired. Further details and advantages of the invention are described below with reference to the accompanying drawing. This drawing shows: Fig. 1 A highly schematic representation of a parallel hybrid drive train according to an embodiment of the invention.

[0030] The parallel hybrid drivetrain 100 comprises an internal combustion engine 1, in this case a diesel engine of a commercial vehicle. The parallel hybrid drivetrain 100 also comprises an electric motor 2, which can be operated as a motor and generator and is connected to a drive shaft 4 of a vehicle transmission 3. The vehicle transmission 3 is the main transmission or gearbox of the commercial vehicle. The internal combustion engine 1, together with the electric motor 2, can be connected to a driven rear axle 8 of the commercial vehicle via the transmission 3. The vehicle transmission 3 is connected on its output side to an axle differential of the driven rear axle 8 via a driveshaft 7, e.g., a cardan shaft.

[0031] As in Fig. As can be seen in Figure 1, the parallel hybrid drivetrain 100 further comprises a coupling 5 arranged between the internal combustion engine 1 and the electric machine 2, by means of which the internal combustion engine 1 can be decoupled from the electric machine 2 and the vehicle transmission 3. When the coupling 5 is engaged, a power flow between the electric machine 2 and the internal combustion engine 1 is possible, so that they can, for example, act together on the transmission 3 via the drive shaft 4.

[0032] The in Fig. The embodiment shown in Figure 1 further comprises a second coupling 6, which is arranged between the electric machine 2 and the vehicle transmission 3. By means of this coupling 6, the power flow between the electric machine 2 and the transmission 3 can be interrupted if necessary, e.g., when the electric machine 2 is used as a starter generator to start the internal combustion engine 1.

[0033] Furthermore, an electrical energy storage device 9 is provided to supply the electric machine 2. In electromotive operation of the electric machine 2, the energy storage device 9 provides electrical energy for the operation of the electric machine 2. In generator operation of the electric machine 2, the energy generated by the electric machine 2 can be stored in the energy storage device 9. The parallel hybrid powertrain can also be implemented as a plug-in hybrid variant, in which the energy storage device 9 can be charged via an external charging interface.

[0034] In purely combustion engine operation, the rear axle 8 is driven only by the internal combustion engine 1. In this operating mode, both clutches 5 and 6 are engaged. In purely electric motor operation, however, the rear axle 8 is driven only by the electric motor 2, with clutch 5 open and clutch 6 engaged. This allows power to flow only from the electric motor 2 to the vehicle transmission 3 and to the axle 8, but no power flow from the electric motor 2 to the internal combustion engine 1. Therefore, the crankshaft and valve train of the internal combustion engine 1 are not driven, thus avoiding drag losses. Furthermore, the known hybrid modes are possible. For example, a so-called boost mode, in which the electric motor 2 and the internal combustion engine work together to drive the axle 8, so that their drive torques are added.Another example is a so-called load point boost operation, in which the combustion engine provides the power both to fully satisfy the driver's desired torque and to simultaneously charge a depleted transmission energy storage system. In this case, the electric machine operates as a generator.

[0035] In the area of ​​the crankcase of the internal combustion engine 1, several auxiliary units are arranged in a manner known per se, of which in Fig. 1 For the sake of simplicity and to highlight the basic idea of ​​the invention, only one auxiliary unit 11 is shown by way of example. Here, the auxiliary unit 11 is, for example, the air compressor that supplies compressed air to a compressed air system of the commercial vehicle. Further auxiliary units (not shown) are arranged in the area of ​​the front end face 1a of the crankcase, for example, the alternator, a water pump, a refrigerant compressor, and a fan.

[0036] Furthermore, a control unit 10 is provided for managing the various operating modes of the vehicle. These operating modes include a purely combustion engine operating mode and a purely electric motor operating mode. The control unit 10 can be designed as a separate control unit or, preferably, as a functional unit that is part of a central engine control unit.

[0037] The control unit 10 is designed to switch between at least two operating modes. In particular, the control unit is designed to open the clutch 5 in the purely electric motor operating mode, so that a crankshaft and a valve train (not shown) of the internal combustion engine 1 are not driven by the electric motor 2. At the same time, however, several auxiliary units necessary for the operation of the vehicle are designed so that they can also be driven when the internal combustion engine is switched off, i.e., when the internal combustion engine 1 is not firing.

[0038] In the Fig.In the embodiment shown in Figure 1, the air compressor 11 can be driven in a conventional manner via a rear gear drive (not shown) of the internal combustion engine 1. Furthermore, the air compressor can also be coupled to the electric motor 2 for drive purposes. For this purpose, the air compressor has a drive shaft 12a, which has a gear 12b at its free end. During a purely electric operating mode of the vehicle, this gear can be engaged with the rotating clutch half 5a of the open clutch 5, so that during purely electric driving, the air compressor 11 is in drive connection with the electric motor 2.

[0039] In this way, the air compressor 11 is also driven when the internal combustion engine 1 is switched off and can thus ensure the function of the compressed air brake even in the purely electric process.

[0040] According to another embodiment, the auxiliary unit, e.g. the air compressor, can be mounted on the crankcase of the internal combustion engine in the conventional manner, but can be driven exclusively and continuously via the rotating clutch half 5a.

[0041] The selection of the operating mode for purely electric driving (purely electric motor operating mode) can be made by the driver or automatically by the vehicle energy management system. If the purely electric motor operating mode is selected, the control unit 10 controls the various components of the parallel hybrid drivetrain accordingly via the signal lines 13, such that the internal combustion engine 1 ceases combustion operation and the electric motor 2 starts electric motor operation, thereby opening the clutch 5 and engaging the gear 12b with the clutch half 5a. The direction of travel, speed, and tractive force can be selected as appropriate by the gear stage of the vehicle transmission 3.

[0042] Although the invention has been described with reference to specific embodiments, it is apparent to a person skilled in the art that various modifications can be made and equivalents can be used as substitutes without departing from the scope of the invention. Consequently, the invention is not intended to be limited to the disclosed embodiments, but rather to encompass all embodiments falling within the scope of the appended claims. In particular, the invention also claims protection for the subject matter and features of the dependent claims independently of the referenced claims. Reference symbol list 1 internal combustion engine 1a Front face of the internal combustion engine 2 Electric Machine 3 Vehicle transmissions 4. Drive shaft of the vehicle transmission 5 First clutch 5a Coupling half 6 Two clutches 7. Drive shaft, e.g. cardan shaft 8. Driven axle, e.g. rear axle 9 Electrical Energy Storage 10 Control unit 11 air compressors 12a Drive shaft of the air compressor 12b gear 13 signal lines 100 Parallel Hybrid Powertrain

Claims

[1] Commercial vehicle, comprising a) comprising a parallel hybrid powertrain (100), - an internal combustion engine (1), - an electric machine (2) connected to a drive shaft (4) of a vehicle transmission (3), which can be operated as a motor and as a generator and - a first coupling (5) arranged between the internal combustion engine (1) and the electric machine (2), by means of which the internal combustion engine (1) can be decoupled from the electric machine (2) and the vehicle transmission (3) in terms of drive, wherein the internal combustion engine (1) together with the electric machine (2) can be connected via the vehicle transmission (3) to at least one axle (8) for drive purposes, wherein the commercial vehicle can be driven optionally in at least one purely internal combustion engine first operating mode and one purely electric motor second operating mode; b) a control device (10) designed to switch between the at least two operating modes, wherein the control device (10) is designed to open the first clutch (5) in the purely electric motor-driven second operating mode, so that a crankshaft and a valve train of the internal combustion engine (1) are not driven by the electric machine (2); and c) a first group of auxiliary units which are mechanically driven independently of the internal combustion engine (1) in the purely electric motor second operating mode and / or are electrically driven, wherein the first group of auxiliary units includes an air compressor (11); characterized by , that the electric machine (2) is permanently connected to the vehicle transmission in a rotationally fixed manner and the first group of auxiliary units is electrified. [2] Commercial vehicle according to claim 1, characterized by , that the first group of auxiliary units includes a power steering pump. [3] Commercial vehicle according to any one of the preceding claims, characterized by a second group of auxiliary units, comprising an alternator, which are arranged in the area of ​​an end face (1a) of the internal combustion engine (1) facing the front of the vehicle and can be driven by the internal combustion engine (1) via a belt drive and / or gear drive. [4] Commercial vehicle according to claim 3, characterized by , that at least one auxiliary unit of the second group is additionally electrically driven. [5] Commercial vehicle according to claim 3, characterized by , a) that the alternator can also be operated by a motor; and b) that the belt drive has a freewheel on the drive wheel; and c) that the control device (10) is designed to drive the auxiliary units of the second group by means of a motor operation of the alternator in the purely electromechanical second operating mode. [6] Commercial vehicle according to claim 3, characterized by , a) that an additional shaft is provided which can be driven by the electric machine (2) and is in drive connection with the belt drive and / or gear drive of the second group of auxiliary units and / or can be brought into contact, b) that the control device (10) is designed to drive the auxiliary shaft for the drive of the auxiliary units of the second group in the purely electromechanical second operating mode. [7] Commercial vehicle according to claim 6, characterized by that the additional wave a) is arranged laterally outside the crankcase of the internal combustion engine (1); or b) is designed as the inner shaft of a crankshaft designed as a hollow shaft.

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