Hybrid vehicle

Abstract

Hybrid vehicle with an internal combustion engine (18), at least two electric motors (20, 22), at least four wheels (12) and a first axle (14) and at least a second axle (16), wherein two of the wheels (12) are assigned to each of the axles (14, 16), wherein the internal combustion engine (18) is provided for driving the wheels (12) of the first axle (14), wherein each of the electric motors (20, 22) is provided to drive one of the wheels (12) of the second axle (16), and wherein the electric motors (20, 22) can be mechanically coupled to each other directly by means of a shaft (44), a clutch (48) and a differential gear (46).

Description

[0001] The invention relates to a hybrid vehicle with an internal combustion engine, an electric motor and at least four wheels.

[0002] Hybrid vehicles, which use both an internal combustion engine and an electric motor for propulsion, are well known.

[0003] In so-called series hybrid vehicles, an internal combustion engine drives a generator that provides electricity for an electric motor. This electric motor, in turn, drives the vehicle's wheels. This approach is inefficient because the series connection of the internal combustion engine and electric motor results in reduced overall system efficiency.

[0004] In other hybrid vehicles, one axle is driven by the combustion engine, while the other axle is driven by an electric motor. The electric motor also serves to recuperate kinetic energy during braking. However, this approach only partially utilizes the available recuperation potential, as energy can only be recovered during braking.

[0005] From DE 10 2013 205 505 A1, a hybrid vehicle is known with a drive unit for the front wheels and a rear-wheel drive unit with a first and second electric motor. The electric motors are each assigned to a rear wheel and drive their respective rear wheels via an interposed planetary gear set.

[0006] US 2004 / 0200654A1 shows a drive device for a vehicle in which one axle is driven by a vehicle drivetrain and the other axle is driven by two electric motors.

[0007] In DE 101 48 113 A1 a drive unit is shown, with two electric machines which are electrically connected to the power electronics which are electrically connected to an electrolyzer, wherein the electrolyzer is coupled to an energy storage device and a water tank.

[0008] DE 10 2012 220 074 A1 discloses a body structure of a hybrid vehicle in which a battery unit is arranged outside the passenger compartment of the vehicle.

[0009] US 4 042 056 A shows a vehicle with another hybrid drive.

[0010] The purpose of the invention is therefore to provide a hybrid vehicle that offers both an efficient drive system and extensive recuperation capabilities.

[0011] The problem is solved by a hybrid vehicle with an internal combustion engine, at least two electric motors, at least four wheels, and a first axle and at least one second axle, with two wheels assigned to each axle. The internal combustion engine is intended to drive the wheels of the first axle, and each of the electric motors is intended to drive one of the wheels of the second axle.

[0012] The term "axle" also includes a pair of opposing wheels attached to the vehicle by means of independent suspension. This includes wheel pairs, such as those commonly found on trucks. The internal combustion engine is connected to the wheels of the first axle in a known manner, for example via a gearbox and / or a clutch, to transmit the generated torque to these wheels. Electric motors can also drive the wheels of the second axle via a gearbox and / or a clutch.

[0013] Because the wheels are driven directly by the combustion engine or individually by the electric motors, a very efficient drive with low losses is possible, as the electrical energy is directly converted into kinetic energy.

[0014] At the same time, the number of driving situations in which recuperation of kinetic energy into electrical energy is possible is increased.

[0015] In addition to the known recuperation possibilities during braking, energy can, for example, be recovered during steering according to the invention.

[0016] For this purpose, the electric motor assigned to the inside wheel of the second axle is operated as a generator, so that only this wheel is braked. This creates a steering torque on the second axle, i.e., a torque around the vehicle's vertical axis, which leads to a rotational movement of the vehicle. In this way, electrical energy can be generated during steering, whereas steering usually consumes energy.

[0017] Similarly, an intervention by the vehicle's automatic stability program (DSC, ESP, etc.) can be carried out by a short generator operation of a single electric motor, which also allows energy to be recovered.

[0018] Furthermore, driving safety is increased by the individual electric motors, as all-wheel drive start support can be optimized and improvements in starting on a hill or driving downhill are possible through the individual control of the wheels of the second axle.

[0019] The first axle can be the front axle of the vehicle and the second axle can be the rear axle, or vice versa. If the electric motors are located on the front axle, the efficiency of the recuperation can be further increased, whereas electric motors on the rear axle are easier to integrate into existing drive concepts.

[0020] Preferably, the vehicle has an on-board electrical system and electrical consumers connected to this system, including the electric motors. The electric motors can feed power into and draw power from the electrical system, thereby increasing the reliability of the power supply to the consumers and the maximum output of the electrical system. The electrical system operates, for example, at a voltage of 48 volts.

[0021] The combustion engine can also have a generator that feeds electricity into the vehicle's electrical system, thus ensuring a basic power supply to consumers while the engine is running. If the generator is a starter generator, it can also draw power from the vehicle's electrical system.

[0022] In one embodiment of the invention, the vehicle electrical system has two parallel cable harnesses extending from the power supply of the combustion engine to each of the electric motors. The electrical loads are connected to one or both of these cable harnesses. This further increases reliability. Furthermore, the braking torques of the individual electric motors can be easily adjusted by switching individual loads on or off in their respective cable harnesses.

[0023] In a further embodiment of the invention, the electric motors can be directly coupled to each other mechanically and / or electrically. The mechanical coupling serves to transmit torque between the two electric motors.

[0024] The electric motors can be coupled without using the vehicle's electrical system. This allows for emergency running functions that keep the vehicle maneuverable to a certain extent, even if, for example, the steering or the electrical system has failed.

[0025] For example, the electric motors can be mechanically coupled to each other by means of a shaft, a clutch and a differential gear, which allows a reliable emergency running system to be implemented.

[0026] An efficient and weight-saving coupling can be achieved by connecting the electric motors directly to a switch via wiring. When the switch is closed, one of the electric motors generates electricity for the other, which is then driven. This creates opposing torques at the wheels, resulting in a steering torque.

[0027] For example, the hybrid vehicle has at least two electric motor batteries, each electrically connected to one of the electric motors. Individual cells, groups of cells, or the entire electric motor battery can be coupled by means of a switch. The coupled cells, groups, or batteries then act as a single unit for both electric motors. The switch can be a semiconductor switch or a contactor. In this way, electrical coupling can be implemented without significant effort.

[0028] Preferably, the vehicle has at least one on-board battery that is electrically connected to the on-board electrical system, so that the consumers can be supplied with power independently of the operation of the combustion engine or the electric motors.

[0029] To save weight and components, the two electric motor batteries can be parts of a shared battery and / or form at least one on-board battery.

[0030] In one embodiment of the invention, the hybrid vehicle can have a control unit configured to control the electric motors in such a way that, for recuperation during steering maneuvers, the electric motor of the inside wheel is operated in generator mode to generate a steering torque. This allows energy to be recovered even during a steering maneuver, for example, when changing lanes. The steering torque generated by the generator operation can be used either to support a conventionally generated steering torque or as the sole steering torque for a steering maneuver.

[0031] Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings, to which reference is made. The drawings show: - Fig. 1 a schematic sketch of a first embodiment of a hybrid vehicle according to the invention, and - Fig. 2 a schematic sketch of a second embodiment of a hybrid vehicle according to the invention.

[0032] In Fig. 1 is a hybrid vehicle 10 schematically indicated as a dashed rectangle.

[0033] The hybrid vehicle 10 has four wheels 12, two of which are arranged on a first axle 14 and the other two on a second axle 16.

[0034] The wheels 12, in particular those of the second axle 16, can be attached to the hybrid vehicle 10 by means of an independent wheel suspension.

[0035] In the embodiments shown, the first axle 14 is the front axle of the hybrid vehicle 10 and the second axle 16 is the rear axle of the hybrid vehicle 10. Thus, the wheels 12 of the first axle 14 can be actuated by a steering mechanism (not shown) in the usual manner. This is indicated by the double arrows in the figures.

[0036] It is of course also conceivable that the second axle 16 represents the front axle of the hybrid vehicle 10 and the first axle 14 is the rear axle of the hybrid vehicle 10.

[0037] The hybrid vehicle 10 also has an internal combustion engine 18, two electric motors 20, 22 and an on-board electrical network 24.

[0038] The internal combustion engine 18, more precisely the output shaft (not shown) of the internal combustion engine 18, is connected to the first axle 14 by means of a gearbox 26 and a clutch 28. The internal combustion engine 18 can thus drive the wheels 12 of the first axle 14 in a known manner.

[0039] Furthermore, the internal combustion engine 18 has an electric generator 30, a starter 32, and a power supply 34. The generator 30 and the starter 32 are connected to the power supply 34, which in turn is integrated into the vehicle's electrical system 24. The generator 30 can supply power to the vehicle's electrical system 24, and the starter 32 can draw power from the vehicle's electrical system 24.

[0040] It is of course also conceivable that the generator 30 and the starter 32 are designed as a single starter generator.

[0041] The electric motors 20, 22 are located on the second axle 16. Each electric motor 20, 22 is connected to one of the wheels 12 of the second axle 16 and can drive its assigned wheel 12. A gearbox and / or a clutch (not shown) can also be provided between the electric motors 20, 22 and the assigned wheels 12.

[0042] In the embodiment shown, the left electric motor 20 is connected to the left wheel 12 of the second axle 16 and the right electric motor 22 is connected to the right wheel 12 of the second axle 16.

[0043] The electric motors 20 and 22 are also electrically connected to the ship's electrical system 24 and can supply power to and draw power from it. The ship's electrical system 24 operates, for example, at a voltage of 48 volts.

[0044] The on-board electrical system 24 has two parallel cable strands 36, 38, which extend from the power supply 34 to each of the electric motors 20, 22.

[0045] The cable strands 36, 38 run separately from each other, being electrically connected by means of the power supply 34.

[0046] In the embodiment shown, the left cable harness 36 extends from the power supply 34 to the left electric motor 20 and the right cable harness 38 extends from the power supply 34 to the right electric motor 22.

[0047] The electric motors 20 and 22 are thus only connected to each other via the power supply 34 through the on-board power network 24.

[0048] Several consumers 40 of the hybrid vehicle 10 are also connected to the on-board electrical system 24. Some consumers 40 are connected to only one of the two cable strands 36, 38, whereas other consumers 40 may be connected to both cable strands 36, 38.

[0049] Cable strands 36, 38 can be configured as supply rails with a supply line to which the loads 40 and the electric motors 20, 22 can be connected. The supply line allows the loads 40 to be supplied with electrical power and simultaneously exchange data (powerline communication).

[0050] The hybrid vehicle 10 also has an on-board battery 42, which is connected to the on-board power supply 24, in the embodiment shown with both cable strands 36, 38, and which serves as an energy storage device.

[0051] A control unit 43 is provided for controlling the electric motors 20, 22 and the consumers 40, which is designed, for example, in the power supply 34 and / or as part of the motor control.

[0052] The control unit 43 can control the regenerative operation of the electric motors 20, 22, among other things, by switching individual loads 40 on or off. For example, if the electric motor 20 is to generate a higher braking torque, a load 40 is switched on by the control unit 43, which is only connected to the left cable harness 36.

[0053] However, regardless of the on-board power grid 24, the electric motors 20, 22 can also be directly coupled to each other.

[0054] In the first embodiment according to Fig. 1 The electric motors 20, 22 can be mechanically coupled to each other for torque transmission by means of shafts 44, a differential gear 46 and a clutch 48.

[0055] Additionally or alternatively, the electric motors 20, 22 can be electrically connected by means of direct wiring 50 (in Fig. 1 (indicated by a dashed line) and electrically connectable to a switch 52.

[0056] To operate the hybrid vehicle 10, the wheels 12 of the first axle 14 are driven by the combustion engine 18.

[0057] The combustion engine 18 can be supported in driving the hybrid vehicle 10 by the electric motors 20, 22 by operating the electric motors 20, 22 and thus also driving the wheels 12 of the second axle 16.

[0058] In this way, a limited all-wheel drive can be implemented. This is helpful, for example, when starting on slippery surfaces and when starting on an incline. The electric motors can generate 20 or 22 different torques, so that slippage can be compensated for or, in addition to propulsion, a steering torque can be generated, for example, to improve acceleration out of a curve.

[0059] The electric motors 20, 22 can also be used for recuperation, i.e., energy recovery, while driving. For this purpose, the electric motors 20, 22 can be operated individually or simultaneously as generators, thus braking the hybrid vehicle 10. In doing so, the electric motors 20, 22 generate both a braking torque at their assigned wheels 12 and electrical current, which can, for example, charge the on-board battery 42.

[0060] The electric motors 20, 22 can also be controlled differently when braking, so that 16 different braking torques are generated at the wheels 12 of the second axle.

[0061] This enables braking interventions by the automatic stability program (DSC, ESP, etc.) of the hybrid vehicle 10.

[0062] However, steering maneuvers, such as changing lanes, can also be performed in this way without turning the wheels 12 of the first axle 14. The different braking torques at the wheels 12 of the second axle 16 generate a steering torque around the vehicle's vertical axis. This causes the hybrid vehicle 10 to rotate and perform a steering maneuver.

[0063] Both steering and interventions by the stability program consume electricity in conventional hybrid vehicles. In the hybrid vehicle 10 according to the invention, electricity is now generated in these situations. The excess energy is stored in the on-board battery 42.

[0064] Even during normal driving, the electric motors 20, 22 can operate as generators and thus supply power to the consumers 40. Accordingly, the generator 30 of the combustion engine 18 only needs to provide a low power output, sufficient to cover the baseline electrical energy consumption. Therefore, the generator 30 can be smaller and more cost-effective.

[0065] The torque fluctuation generated during a shifting operation of the combustion engine drive can also be mitigated or compensated by additional torques from the electric motors 20, 22, thereby improving driving comfort.

[0066] In the event of a failure of the on-board electrical system 24 or parts thereof, the two electric motors 20, 22 can be switched to an emergency running mode. For this purpose, the two electric motors 20, 22 are coupled, i.e., the clutch 48 and / or the switch 52 are closed.

[0067] In the case of a mechanical coupling, the differential gear can generate 46 different torques at the wheels 12 of the second axle 16, resulting in a torque around the vehicle's vertical axis and thus a steering torque. The vehicle therefore retains a certain degree of maneuverability.

[0068] In the case of electrical coupling, a steering torque can be generated by operating one of the electric motors 20, 22 as a generator and supplying the resulting current to the other electric motor 22, 20 via the wiring 50. The other electric motor 22, 20 is then driven by this current and drives its assigned wheel 12. Thus, a braking torque is applied to one of the wheels 12 of the second axle 16, and a driving torque is applied to the other, thereby generating a steering torque.

[0069] Through the electrical coupling, i.e. the wiring 50, a failure of the power supply 34 can also be partially compensated and a coupling between the two cable strands 36, 38 can be restored via the electric motors 20, 22.

[0070] In this way, further fallback levels for emergencies are realized in the hybrid vehicle 10.

[0071] In Fig. Figure 2 shows a second embodiment of the invention, which essentially corresponds to the first embodiment. Therefore, only the differences will be discussed below, and identical and functionally equivalent parts are provided with the same reference numerals.

[0072] The second embodiment differs from the first embodiment in that the coupling between the two electric motors 20, 22 is designed differently.

[0073] In the second embodiment, the hybrid vehicle 10 has two electric motor batteries 54, which can be configured as parts of a split battery 56. For example, the two electric motor batteries 54 or the split battery 56 form the on-board battery 42.

[0074] Each of the two electric motor accumulators 54 is electrically connected to one of the electric motors 20, 22, so that each electric motor 20, 22 has its own electric motor accumulator 54.

[0075] The two electric motor accumulators 54 can also be directly connected to the respective cable harness 36, 38 of the associated electric motor 20, 22.

[0076] Furthermore, the two electric motor accumulators 54 can be connected to each other. This can be done either by connecting the electric motor accumulators 54 as a whole, by connecting individual cells of the two electric motor accumulators 54 individually, or as groups of cells.

[0077] The coupling is effected by a switch 58, such as a semiconductor switch or a contactor. If, as described in the first embodiment, coupling of the two electric motors 20, 22 becomes necessary, the switch 58 is closed. The two electric motor accumulators 54 are thus coupled and then serve as a common accumulator for both electric motors 20, 22.

[0078] In this way, an electrical connection is established between the two electric motors 20, 22 and also between the two cable strands 36, 38. This electrical connection is similar to the electrical connection via the wiring 50 in the first embodiment.

[0079] Naturally, the features of the two embodiments can be combined in any way desired. In particular, the second embodiment can also include a mechanical coupling of the electric motors 20, 22 or an electrical coupling of the electric motors 20, 22 by means of a cable 50.

Claims

[1] Hybrid vehicle with an internal combustion engine (18), at least two electric motors (20, 22), at least four wheels (12) and a first axle (14) and at least a second axle (16), wherein two of the wheels (12) are assigned to each of the axles (14, 16), wherein the internal combustion engine (18) is provided for driving the wheels (12) of the first axle (14), wherein each of the electric motors (20, 22) is provided to drive one of the wheels (12) of the second axle (16), and wherein the electric motors (20, 22) can be mechanically coupled to each other directly by means of a shaft (44), a clutch (48) and a differential gear (46). [2] Hybrid vehicle according to claim 1, characterized by , that the first axle (14) is the front axle of the hybrid vehicle (10) and the second axle (16) is the rear axle of the hybrid vehicle (10) or vice versa. [3] Hybrid vehicle according to claim 1 or 2, characterized by, that the hybrid vehicle (10) has an on-board electrical network (24) and consumers (40) which are electrically connected to the on-board electrical network (24), wherein the electric motors (20, 22) are electrically connected to the on-board electrical network (24). [4] Hybrid vehicle according to claim 3, characterized by , that the internal combustion engine (18) has a generator (30) that can feed electricity into the on-board electrical system (24). [5] Hybrid vehicle according to claim 3 or 4, characterized by , that the on-board electrical system (24) has two parallel cable strands (36, 38) which extend from a power supply (34) of the internal combustion engine (18) to each of the electric motors (20, 22). [6] Hybrid vehicle according to any one of the preceding claims, characterized by , that the electric motors (20, 22) can be directly electrically coupled to each other. [7] Hybrid vehicle according to claim 6, characterized by, that the electric motors (20, 22) can be coupled to each other by means of a direct wiring (50) with a switch (52). [8] Hybrid vehicle according to one of claims 6 to 7, characterized by , that the hybrid vehicle (10) has at least two electric motor accumulators (54), each of which is electrically connected to one of the electric motors (20, 22), wherein individual cells of the electric motor accumulators (54), groups of cells or the entire electric motor accumulators (54) can be coupled by means of a switch (58). [9] Hybrid vehicle according to any one of the preceding claims, characterized by , that the hybrid vehicle (10) has at least one on-board battery (42) which is electrically connected to the on-board electrical network (24). [10] Hybrid vehicle according to claims 8 and 9, characterized by , that the two electric motor accumulators (54) are parts of a shared accumulator (56) and / or form at least one on-board accumulator (42). [11] Hybrid vehicle according to any one of the preceding claims, characterized by , that the hybrid vehicle has a control unit (43) which is configured to control the electric motors (20, 22) in such a way that, for recuperation during steering maneuvers, the electric motor (20, 22) of the inside wheel (12) is operated as a generator to produce a steering torque.

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