Method for controlling the braking of a vehicle

Abstract

Method, carried out by a control device (48), for controlling the braking of a vehicle (1) which has an internal combustion engine (4), a first electric machine (14), a second electric machine (16) and a transmission (2), wherein the transmission (2) has: an input wave (8); a first main wave (34); a second main wave (36); an output shaft (20) which is connected to the drive wheels (6) of the vehicle (1); an intermediate shaft (18) which is connected to the first main shaft (34), the second main shaft (36) and the output shaft (20); a first gear pair (G1) which is connected to the first main shaft (34) and the intermediate shaft (18); a second gear pair (G2), which is connected to the second main shaft (36) and is connected to the intermediate shaft (18); a first planetary gear set (10) which is connected to the input shaft (8) and the first main shaft (34); and a second planetary gear (12) which is connected to the first planetary gear (10) and the second main shaft (36); wherein the internal combustion engine (4) is connected to the input shaft (8), the first electric machine (14) is connected to the first planetary gear (10) and the second electric machine (16) is connected to the second planetary gear (12) such that drive torque can be applied to the first main shaft (34) and the second main shaft (36) by means of the internal combustion engine (4), the first electric machine (14) and the second electric machine (16), wherein the method comprises: a determination (s101) of a required braking force at the output shaft (20) to maintain or reduce the speed of the vehicle (1); a finding (s102) that the first and second planetary gear sets (10; 12) are unlocked and brought into a neutral position; a control (s103) of the internal combustion engine (4) by means of at least one of the first and second electric machines (14, 16) to a rotational speed at which an engine braking force corresponds to the determined braking force; and a control (s104) of the internal combustion engine (4) into an engine braking mode.

Description

TECHNICAL FIELD

[0001] The invention relates to a method for controlling the braking of a vehicle. The invention also relates to a vehicle, a computer program, and a computer-readable medium. BACKGROUND

[0002] During engine braking of a vehicle, the throttle and the fuel supply to the combustion engine are blocked. When the air in the cylinders is compressed during the compression stroke, the pistons, via the piston rods, exert a braking torque on the crankshaft, which is then acted upon by the vehicle wheels via the drive shafts, a propeller shaft, and the transmission. Since the crankshaft interacts directly with the vehicle's drive wheels during engine braking, the braking force of the pistons and rods acting on the crankshaft decelerates the vehicle during engine braking.

[0003] The braking force of an internal combustion engine depends on the rotational speed of the internal combustion engine. The braking force of the internal combustion engine increases with the rotational speed of the internal combustion engine. To use the braking force of a vehicle's internal combustion engine to slow it down, a transmission in the vehicle's drivetrain can be downshifted to increase the rotational speed of the internal combustion engine. The braking force of the internal combustion engine thus corresponds specifically to the rotational speed reached by the internal combustion engine after the downshift. The rotational speed of the internal combustion engine depends on the vehicle speed and the gear ratio of the transmission.

[0004] Document US 2002 / 0 091 028 A1 describes a power transmission system for a hybrid motor vehicle with an internal combustion engine and electric motors. The system features a planetary gear and a continuously variable transmission. The internal combustion engine and the electric motors can be used for braking the vehicle.

[0005] Document DE 11 2012 005 347 T5 describes a power distribution device for a hybrid drivetrain, comprising an epicyclic gear consisting of a first and a second gearwheel and a planetary gear. Each gearwheel can be connected to an electric motor or an internal combustion engine. The epicyclic gearwheel also includes a bypass gear configured to be coupled to or decoupled from the gearwheels. Such a configuration of a power distribution device allows an internal combustion engine to be temporarily used as the sole power source during a start-up process.

[0006] Document DE 10 2011 086 057 A1 describes a transmission mechanism for a hybrid vehicle that efficiently recovers electrical energy during braking. The shift range is changed depending on the level of braking demand. SHORT DESCRIPTION

[0007] Despite known technical solutions in this area, it is desirable to provide a method for controlling the braking of a vehicle which overcomes or at least reduces some of the disadvantages of the prior art.

[0008] An object of the invention is therefore to provide a novel and advantageous method for controlling the braking of a vehicle, which method enables precise control of the braking force of an internal combustion engine. A further object is to provide a novel and advantageous vehicle in which the speed can be maintained or reduced by means of precise control of the braking force of an internal combustion engine. A further object of the invention is to provide a novel and advantageous computer program and a computer-readable medium.

[0009] The objects stated herein are achieved by a method, a vehicle, a computer program and a computer-readable medium according to the appended claims.

[0010] Thus, according to a variant of the present invention, a method is provided which is carried out by a control device for controlling the braking of a vehicle. The vehicle comprises: an internal combustion engine, a first electric machine (electric motor), a second electric machine, and a transmission. The transmission comprises: an input shaft; a first main shaft; a second main shaft; an output shaft connected to the drive wheels of the vehicle; an intermediate shaft (countershaft) connected to the first main shaft, the second main shaft, and the output shaft; a first gear pair connected to the first main shaft and the intermediate shaft; a second gear pair connected to the second main shaft and the intermediate shaft; a first planetary gear connected to the input shaft and the first main shaft;and a second planetary gear set connected to the first planetary gear set and the second main shaft; wherein the internal combustion engine is connected to the input shaft, and the first electric machine is connected to the first planetary gear set and the second electric machine is connected to the second planetary gear set such that drive torque can be applied to the first main shaft and the second main shaft by means of the internal combustion engine, the first electric machine, and the second electric machine. The method comprises: determining a required braking force at the output shaft to maintain or reduce the speed of the vehicle; determining that the first and second planetary gear sets are released and placed in a neutral position;controlling the internal combustion engine by means of at least one of the first and second electric machines to a rotational speed at which the engine braking power corresponds to the determined braking power; and controlling the internal combustion engine into an engine braking mode.

[0011] According to a further variant of the invention, a vehicle is provided. The vehicle comprises: an internal combustion engine; a first electric machine (electric motor); a second electric machine (electric motor); a transmission, and a control device. The transmission comprises: an input shaft, a first main shaft; a second main shaft; an output shaft connected to drive wheels of the vehicle; an intermediate shaft (countershaft) connected to the first main shaft, the second main shaft, and the output shaft; a first gear pair connected to the first main shaft and the intermediate shaft; a second gear pair connected to the second main shaft and the intermediate shaft; a first planetary gear connected to the input shaft and the first main shaft; and a second planetary gear connected to the first planetary gear and the second main shaft.wherein the internal combustion engine is connected to the input shaft, the first electric machine is connected to the first planetary gear set, and the second electric machine is connected to the second planetary gear set, so that drive torque can be transmitted to the first main shaft and the second main shaft by means of the internal combustion engine, the first electric machine, and the second electric machine. The control device is configured to: determine a required braking force on the output shaft to maintain or reduce the speed of the vehicle; verify that the first and second planetary gear sets are released and placed in a neutral position; control the internal combustion engine, by means of the first and / or the second electric machine, to a rotational speed at which the engine braking force corresponds to the determined braking force; and place the engine in an engine braking mode.

[0012] With such a method, an appropriate control of the braking force of an internal combustion engine is achieved, which causes the speed of the vehicle to be maintained or reduced by means of the appropriate control of the braking force of an internal combustion engine.

[0013] With the aforementioned transmission configuration, it is possible to control the rotational speed of the engine independently of the gear ratio. This makes it possible to control the braking force of the engine brake by controlling the engine speed. The engine brake of the internal combustion engine generates braking force in the drivetrain, and at least one of the first and second electric motors controls the rotational speed of the internal combustion engine. The electric motors can, over a very short period of time, control the internal combustion engine to a rotational speed that corresponds to the determined braking force. Therefore, a braking force close to the braking torque intended to be achieved by the engine braking is achieved at the output shaft.

[0014] Other objects, advantages, and novel features of the invention will become more apparent to those skilled in the art from the following detailed description and from the practice of the invention. While examples of the invention are described in detail below, it is to be understood that the invention is not limited to the details described. Those skilled in the art having access to the teachings herein will recognize further applications, modifications, and implementations, particularly in other fields within the scope of the invention. BRIEF DESCRIPTION OF THE CHARACTERS

[0015] For a deeper understanding of the invention and for further objects and advantages thereof, a detailed description is given below, which should be read in conjunction with the accompanying figures, in which the same reference numerals designate corresponding components: Fig. 1 shows schematically a side view of a vehicle according to an embodiment; Fig. 2 schematically shows a drive train of a vehicle according to an embodiment; Fig. 3 shows a diagram according to an embodiment; Fig. 4 shows a flowchart for a method for controlling the braking of a vehicle according to an embodiment; and Fig. 5 schematically shows a computer according to an embodiment. DESCRIPTION OF DETAILS

[0016] According to a variant of the present description, a method is provided, which is carried out by a control device, for controlling the braking of a vehicle. The vehicle has an internal combustion engine, a first electric machine, a second electric machine, and a transmission. The transmission comprises: an input shaft; a first main shaft; a second main shaft; an output shaft connected to drive wheels of the vehicle; an intermediate shaft connected to the first main shaft, the second main shaft, and the output shaft; a first gear pair connected to the first main shaft and the intermediate shaft; a second gear pair connected to the second main shaft and the intermediate shaft; a first planetary gear connected to the input shaft and the first main shaft; and a second planetary gear connected to the first planetary gear and the second main shaft.wherein the internal combustion engine is connected to the input shaft, the first electric machine is connected to the first planetary gear set, and the second electric machine is connected to the second planetary gear set such that drive torque can be transmitted to the first main shaft and the second main shaft by means of the rotary motor, the first electric machine, and the second electric machine. The method comprises: determining a required braking force on the output shaft to maintain or reduce the speed of the vehicle; determining that the first and second planetary gear sets are released and placed in a neutral position; controlling the internal combustion engine by means of the first and / or second electric machine to a rotational speed at which the engine braking force corresponds to the determined braking force; and controlling the internal combustion engine into an engine braking mode.

[0017] Engine braking of a vehicle can reduce the vehicle's speed. On the other hand, engine braking can also maintain the vehicle's speed, for example when the vehicle is driving on a downhill road and engine braking is activated. Depending on the amount of engine braking force acting on the input shaft of the combustion engine and thus also on the output shaft of the transmission and on the drive wheels, the vehicle's speed can be maintained or reduced. The amount of engine braking force acting on the input shaft of the combustion engine can be calculated from the determined required braking force at the output shaft to maintain or reduce the vehicle's speed. The determination of the braking force required at the output shaft can be carried out using sensors arranged in the vehicle and on the vehicle's drivetrain.Determining the required braking force at the output shaft can also be performed using information about the vehicle and the road on which the vehicle is traveling. Before or after determining the required braking force, or simultaneously with determining the required braking force, it is ensured that the first and second planetary gears are released (unlocked) and placed in a neutral position. When the first and second planetary gears are unlocked and placed in a neutral position, the first and second electric machines can rotate components of the first and second planetary gears independently of any rotational speed of the first and second main shafts.Due to the configuration of the transmission, the first and second electric machines can generate a rotational speed of the internal combustion engine when it is ensured that the first and second planetary gears are unlocked and placed in a neutral position. Thus, when the required braking force is determined and it is ensured that the first and second planetary gears are unlocked and placed in a neutral position, the internal combustion engine is controlled by at least one of the first and second electric machines to a rotational speed at which the engine braking force corresponds to the determined braking force. The control device receives information about the braking force and braking torques for the internal combustion engine at different rotational speeds of the internal combustion engine. Such information can be stored in a memory of the control device.If the internal combustion engine has a rotational speed at which the engine braking force corresponds to the determined braking force, the internal combustion engine is controlled into engine braking mode. Controlling the internal combustion engine into engine braking mode can be achieved by controlling components in the internal combustion engine that impose a restriction in the internal combustion engine's exhaust system.

[0018] According to one embodiment, the determination of a required braking force on the output shaft to maintain or reduce the speed of the vehicle includes a determination of the weight, speed and air resistance of the vehicle as well as the inclination of the vehicle in its longitudinal direction.

[0019] The weight of the vehicle affects the braking force required to slow the vehicle. A heavier vehicle requires more braking force than a lighter vehicle to maintain or reduce speed. The speed of the vehicle affects the required braking force. A vehicle traveling at high speed requires more braking force than a vehicle traveling at lower speed to maintain or reduce speed. Air resistance and friction from the tires and bearings on the rotating shafts affect the braking force required to slow the vehicle. High air resistance and friction from the tires and bearings can reduce the braking force required at the output shaft to maintain or reduce the vehicle's speed. Air resistance and friction from the tires and bearings can increase with increasing speed.The vehicle's longitudinal inclination can also influence the required braking force. If the vehicle is driving downhill on a road, the inclination of the vehicle's longitudinal axis corresponds to the gradient of the hill. A large longitudinal inclination of the vehicle requires more braking force than a smaller longitudinal inclination of the vehicle in order to maintain or reduce the vehicle's speed. Thus, more braking force is required on a steep downhill stretch compared to the braking force required on a gentle downhill stretch. Determining the vehicle's weight may involve receiving information about the vehicle's weight from a memory in the control device and / or from a weight sensor in the vehicle. Determining the speed may involve receiving information about the vehicle's speed from a speed sensor in the vehicle.Determining the vehicle's air resistance may involve receiving information about the vehicle's air resistance from a memory in the control device. Determining the vehicle's longitudinal inclination may involve receiving information about the longitudinal inclination from an inclination sensor in the vehicle or from a topographical road map.

[0020] According to one embodiment, determining that the first and second planetary gear sets are unlocked and placed in a neutral position includes determining that a first axially slidable clutch sleeve disconnects a first sun gear from a first planet gear carrier of the first planetary gear set and that a second axially slidable clutch sleeve disconnects a second sun gear from a second planet gear carrier of the second planetary gear set.

[0021] The first and second axially movable clutch bushings can be moved by actuators. When engine braking is to be activated, the first and second planetary gears are unlocked and moved to a neutral position by axially moving the bushings by the actuators. A position sensor on the first axially movable clutch bushing can detect that the first sun gear is separated from the first planet carrier of the first planetary gear. A position sensor on the second axially movable clutch bushing can detect that the second sun gear is separated from the second planet carrier of the second planetary gear.

[0022] According to one embodiment, controlling the internal combustion engine by means of at least one of the first and second electric machines to a rotational speed at which an engine braking force corresponds to the determined braking force includes controlling the internal combustion engine to a rotational speed independent of the speed of the first and second main shafts in the transmission.

[0023] When it is determined that the first and second planetary gear sets are unlocked and placed in a neutral position, the first and second electric machines can control the rotational speed of the internal combustion engine independently of the speed of the first and second main shafts in the transmission. The first and second main shafts can rotate at a respective rotational speed that depends on the vehicle speed. The first sun gear is connected to the first main shaft. The first axially movable clutch sleeve separates the first planet gear carrier from the first sun gear and thus also from the first main shaft. The first planet gear carrier is connected to the second sun gear, but the second sun gear is separated from the second main shaft by means of the second axially movable clutch sleeve.Therefore, the first and second electric machines can control the rotational speed of the first planetary gear carrier and the second sun gear. As a result, the first and second electric machines can control the rotational speed of the internal combustion engine, since the internal combustion engine is connected to the input shaft of the transmission and the first planetary gear carrier is also connected to the input shaft of the transmission.

[0024] According to one embodiment, controlling the internal combustion engine into an engine braking mode includes controlling an exhaust brake of the internal combustion engine.

[0025] The exhaust brake of an internal combustion engine may include a throttle valve in the exhaust system, which is closed to activate the exhaust brake. Closing the exhaust system with the valve causes air in the cylinders of the internal combustion engine to be compressed not only during the compression stroke, but also during the exhaust stroke. The compression of the air during both the compression and exhaust strokes creates a braking force on the crankshaft of the internal combustion engine. If the exhaust brake is activated, then the engine brake is also activated. The exhaust brake of an internal combustion engine can also be controlled by deactivating one or more exhaust valves in the internal combustion engine.

[0026] According to one embodiment, the method further includes controlling at least one of the first and second electric machines to generate additional braking force at the output shaft.

[0027] If the internal combustion engine is unable to generate sufficient braking force, at least one of the first and second electric machines can be controlled to generate additional braking force at the output shaft. The internal combustion engine is capable of generating braking force up to a certain limit, which depends on characteristics of the internal combustion engine, such as the cylinder volume of the internal combustion engine and the type of exhaust brake of the internal combustion engine. Electrical power from an energy storage unit can be transmitted to at least one of the first and second electric machines, and at least one of the first and second electric machines can generate braking force in addition to the braking force generated by the internal combustion engine.

[0028] According to one embodiment, controlling at least one of the first and second electric machines to generate additional braking force at the output shaft includes controlling at least one of the first and second electric machines into a generator mode.

[0029] The additional braking force of at least one of the first and second electric machines may be generated by controlling at least one of the first and second electric machines into a generator mode in which the at least one of the first and second electric machines generates electrical energy for an energy storage unit in the vehicle.

[0030] The present description also relates to a computer program with instructions that, when executed by a computer, cause the computer to perform a method described herein. The invention further includes a computer-readable medium with instructions that, when executed by a computer, cause the computer to perform a method described herein.

[0031] The transmission may include any suitable number of gear pairs. Each gear pair may include a pinion disposed on the intermediate shaft and a pinion disposed on the first main shaft or the second main shaft. The pinions may be configured to be mechanically connectable and detachable with respect to the intermediate shaft. The pinions may be fixedly attached to the first main shaft or the second main shaft. When a pinion is connected to the intermediate shaft, the pinion rotates together with the intermediate shaft. When a pinion is disconnected from the intermediate shaft, the pinion can rotate with respect to the intermediate shaft. When the pinion of a gear pair is connected to the intermediate shaft, the corresponding gear is engaged. Thus, a given number of gear steps can be achieved by means of the transmission.A gear pair can thus be separated, with the corresponding pinion being separated from the intermediate shaft, and a gear pair can be connected when the corresponding pinion is connected to the intermediate shaft. On the other hand, the pinions can be fixedly connected to the intermediate shaft, and the pinions can be mechanically connectable and separable with respect to the first main shaft or the second main shaft. In a transmission that can split drive torque between a first main shaft and a second main shaft, a gear pair can always be connected to the first main shaft and the intermediate shaft. Thus, a gear associated with the first main shaft can always be engaged, even when no drive torque is applied to the first main shaft. Similarly, a gear pair can always be connected to the second main shaft and the intermediate shaft.

[0032] The pinions may be configured for a releasable mechanical connection to the intermediate shaft or the first main shaft or the second main shaft by means of coupling bushings. The coupling bushings may each comprise an annular bushing that is axially displaceable between a connected state and a disconnected state. The bushing may be displaced between the connected state and the disconnected state by means of an electrical element.

[0033] Each gear pair of the transmission has a gear ratio adapted to the desired driving characteristics of the vehicle. The gear pair with the highest gear ratio, compared to the other gear pairs, is suitably connected when the lowest gear is engaged. The gear pair with the highest gear ratio can also be referred to as the starting gear. The gear pair associated with the starting gear can be connected to the second main shaft and the intermediate shaft. This allows the vehicle to be started from a standstill without interrupting the power transmission to a power consumer connected to the auxiliary shaft.

[0034] The auxiliary shaft (counter shaft) can be connected to the first main shaft via the first gear pair or any other gear pair / pinion connected to the first main shaft. A sub-pinion can be fixedly mounted on the auxiliary shaft. The sub-pinion can mesh with the first gear pair or any other gear pair connected to the first main shaft. The sub-pinion can therefore mesh with the first pinion on the first main shaft. When the auxiliary shaft is connected to the first main shaft, this means that the power consumer connected to the auxiliary shaft is not connected to the vehicle's propulsion.

[0035] The transmission may further comprise a first planetary gear set connected to the internal combustion engine and the first main shaft; and a second planetary gear set connected to the first planetary gear set and the second main shaft, wherein the first electric machine is connected to the first planetary gear set and the second electric machine is connected to the second planetary gear set. Control of the drivetrain may thus include controlling the internal combustion engine and / or the first electric machine and / or the second electric machine to gradually transfer drive torque from the second main shaft to the first main shaft. The drivetrain is thus a hybrid drivetrain in this embodiment. This drivetrain enables gear shifting without torque interruption.The drive train with two planetary gear units also makes it possible to avoid the use of conventional slip clutches between the combustion engine and the transmission.

[0036] The first planetary gear set may have a first ring gear connected to the first electric machine. The first planetary gear set may also have a first sun gear and a first planet gear carrier. The second planetary gear set may have a second ring gear connected to the second electric machine. The second planetary gear set may further have a second sun gear and a second planet gear carrier. The first planet gear carrier may be connected to the internal combustion engine. The first planet gear carrier may further be connected to the second sun gear of the second planetary gear set. The first main shaft may be connected to the first sun gear of the first planetary gear set. The second main shaft may be connected to the second planet gear carrier. The first planet gear carrier in the first planetary gear set may be directly connected to the internal combustion engine via the input shaft.On the other hand, the first planetary gear carrier is connected to the internal combustion engine via a clutch device. The second planetary gear carrier in the second planetary gear set can be directly connected to the second main shaft. The first sun gear in the first planetary gear set can be connected to the first main shaft, and the second planetary gear carrier in the second planetary gear set can be connected to the second main shaft. A first set of planetary gears can be mounted on the first planetary gear carrier. A second set of planetary gears can be mounted on the second planetary gear carrier. The first set of planetary gears cooperates with the first ring gear and the first sun gear. The second set of planetary gears cooperates with the second ring gear and the second sun gear.

[0037] The electric motors connected to the planetary gears can deliver power and / or torque depending on the desired operating mode. The electric motors can also supply power to each other during certain operating times.

[0038] A first and a second clutch sleeve can be arranged between the planet carrier and the sun gear of the respective planetary gear set. The clutch sleeves can be configured to connect (lock) the respective planet carrier with respect to the respective sun gear. When the planet carrier and the sun gear are connected, the power from the internal combustion engine is propagated via the planet carrier, the clutch sleeve, the sun gear, and further via the first main shaft and / or the second main shaft. In this way, the planet gears do not absorb any torque. The dimensions of the planet gears can be adapted only to the torque of the electric machine and not to the torque of the internal combustion engine, which in turn means that the planet gears can be designed with smaller dimensions. Thus, the drive train according to this embodiment has a compact structure, low weight, and low manufacturing costs.

[0039] In order to separate the planet carrier and the sun gear from each other, the first and / or the second electric machine must be controlled such that torque equilibrium is achieved in the planetary gear. Torque equilibrium refers to a condition in which a torque acts on a ring gear in the planetary gear, which is a product of the torque acting on the planet carrier and the gear ratio of the planetary gear, while at the same time a torque acts on the sun gear of the planetary gear, which is a product of the torque acting on the planet carrier and (1 - the gear ratio of the planetary gear). If two components of the planetary gear (sun gear, ring gear, or planet carrier) are connected by a coupling bush, then the coupling bush does not transmit any torque between the components of the planetary gear when torque equilibrium exists.Accordingly, the clutch sleeve can be easily moved and the components of the planetary gear can be separated.

[0040] The first main shaft and the second main shaft are connectable to the internal combustion engine, the first electric machine, and the second electric machine, so that drive torque can be applied to the first main shaft and the second main shaft simultaneously. Drive torque can thus be provided in parallel. Drive torque is defined here as a torque that is provided by means of the internal combustion engine and / or the first electric machine and / or the second electric machine for propelling the vehicle. Thus, the first main shaft and the second main shaft can be arranged such that drive torque can be provided via at least one of the three assemblies: internal combustion engine, first electric machine, and second electric machine, and wherein the drive torque can be split (distributed) between the first main shaft and the second main shaft.

[0041] Controlling the driveline for a gradual transition of drive torque from the second main shaft to the first main shaft means that the driveline is controlled so that drive torque at the second main shaft is gradually reduced and drive torque at the first main shaft gradually increases. When the vehicle starts and moves from a standstill, drive torque is only applied to the second main shaft. Thus, when the vehicle starts, essentially no drive torque is applied to the first main shaft. The drive torque generated at the output shaft is therefore only transmitted to the second main shaft and the intermediate shaft. If the drive torque is gradually transferred from the second main shaft to the first main shaft, drive torque at the output shaft is transmitted from both the first main shaft and the second main shaft.

[0042] According to a further variant of the present description, a vehicle is provided. The vehicle has an internal combustion engine; a first electric machine; a second electric machine; a transmission, and a control device. The transmission comprises: an input shaft; a first main shaft; a second main shaft; an output shaft connected to drive wheels of the vehicle; an intermediate shaft connected to the first main shaft, the second main shaft, and the output shaft; a first gear pair connected to the first main shaft and the intermediate shaft; a second gear pair connected to the second main shaft and the intermediate shaft; a first planetary gear set connected to the input shaft and the first main shaft; and a second planetary gear set connected to the first planetary gear set and the second main shaft.wherein the internal combustion engine is connected to the input shaft, the first electric machine is connected to the first planetary gear set, and the second electric machine is connected to the second planetary gear set such that drive torque can be applied to the first main shaft and the second main shaft by means of the internal combustion engine, the first electric machine, and the second electric machine. The control device is configured to: determine a required braking force on the output shaft to maintain or reduce the speed of the vehicle; determine that the first and second planetary gear sets are unlocked and placed in a neutral position; control the internal combustion engine, by means of at least one of the first and second electric machines, to a rotational speed at which an engine braking force corresponds to the determined braking force; and control the internal combustion engine into an engine braking mode.

[0043] It is apparent that all features of the embodiments described in connection with the method for execution by a control device also apply to a vehicle and to the control device according to the description. That is, the control device can be configured to execute any of the methods described here and the associated steps according to the various embodiments described above.

[0044] The control device can be configured to determine the weight, speed, and air resistance of the vehicle, as well as the inclination of the vehicle in its longitudinal direction. The control device can be configured to determine that a first axially displaceable clutch sleeve separates a first sun gear from a first sun gear carrier of the first planetary gear set, and that a second axially displaceable clutch sleeve separates a second sun gear from a second planet gear carrier of the second planetary gear set. The control device can further be configured to control the internal combustion engine to a rotational speed independent of the speed of the first and second main shafts in the transmission.

[0045] The control device can be configured to control an exhaust brake of the internal combustion engine. The control device can be configured to control at least one of the first and second electric machines to generate additional braking force at the output shaft. The control device can also be configured to control at least one of the first and second electric machines into a generator mode.

[0046] The present description is now further supplemented with reference to the attached figures.

[0047] Fig. Figure 1 schematically shows a side view of a vehicle 1. The vehicle 1 has a transmission 2 and a drive unit 4, which are included in a drive train 3 of the vehicle 1. The drive unit 4 can be an internal combustion engine connected to the transmission 2. The transmission 2 is also connected to drive wheels 6 of the vehicle 1.

[0048] Fig. Figure 2 schematically shows a drive train 3 according to an embodiment. The drive train 3 can be used in a vehicle 1 according to Fig. 1. The drive train 3 has an internal combustion engine 4, a first electric machine (electric motor) 14, and a second electric machine (electric motor) 16. The internal combustion engine 4 is connected to the transmission 2 via an input shaft 8 of the transmission 2. The internal combustion engine 4 is provided with an exhaust brake 60. The transmission 2 has a first main shaft 34; a second main shaft 36; an output shaft 20 connected to drive wheels 6 of the vehicle 1; an intermediate shaft (countershaft) 18 connected to the first main shaft 34, the second main shaft 36, and the output shaft 20; a first gear pair G1 connected to the first main shaft 34 and the intermediate shaft 18; and a second gear pair G2 connected to the second main shaft and the intermediate shaft 18.The first main shaft 34 and the second main shaft 36 are connectable to the internal combustion engine 4, a first electric machine 14 and a second electric machine 16 such that drive torque can be applied simultaneously to the first main shaft 34 and the second main shaft 36.

[0049] The transmission 2 further has a first planetary gear 10 and a second planetary gear 12. The first planetary gear 10 is connected to the input shaft 8. The second planetary gear 12 is connected to the first planetary gear 10. The first planetary gear 10 has a first ring gear 22 which is connected to a first rotor 24 of the first electric machine 14. The first planetary gear 10 further has a first sun gear 26 and a first planet gear carrier 50. The second planetary gear 12 has a second ring gear 28 which is connected to a second rotor 30 of the second electric machine 16. The second planetary gear 12 further has a second sun gear 32 and a second planet gear carrier 51. The first planet gear carrier 50 can be connected to the input shaft 8. The first planet gear carrier 50 can also be connected to the second sun gear 32 of the second planetary gear 12.

[0050] The first main shaft 34 can be connected to the first sun gear 26 of the first planetary gear set 10. The second main shaft 36 can be connected to the second planetary gear carrier 51. The first and second sun gears 26, 32 can be arranged coaxially. The first main shaft 34 can extend coaxially within the second main shaft 36. It is also possible to arrange the first main shaft 34 parallel and adjacent to the second main shaft 36.

[0051] The first electric machine 14 may have a first stator 40, which may be connected to the transmission housing 42 surrounding the transmission 2. The second electric machine 16 may have a second stator 44, which is connected to the transmission housing 42. The first electric machine 14 and the second electric machine 16 are connected to an energy storage device (not shown), such as a battery, which can drive the electric machines 14, 16 depending on the operating state of the vehicle 1. In other operating states, the electric machines 14, 16 can operate as generators, with energy being supplied to the energy storage device. In some operating states, the electric machines 14, 16 can drive one another. Electrical power is then transferred from one of the electric machines 14, 16 to the other electric machine 14, 16.

[0052] A first set of planet gears 52 is mounted on the first planet carrier 50. A second set of planet gears 54 is mounted on the second planet carrier 51. The first set of planet gears 52 meshes with the first ring gear 22 and the first sun gear 26. The second set of planet gears 54 meshes with the second ring gear 28 and the second sun gear 32.

[0053] A first axially displaceable clutch sleeve 56 is arranged between the first sun gear 26 and the first planetary gear carrier 50. When the first clutch sleeve 56 is adjusted so that the first sun gear 26 and the first planetary gear carrier 50 are connected to each other, the first sun gear 26 and the first planetary gear carrier 50 cannot rotate relative to each other. The first planetary gear carrier 50 and the first sun gear 56 therefore rotate at the same rotational speed.

[0054] A second axially displaceable clutch sleeve 58 is arranged between the second sun gear 32 and the second planet carrier 51. If the second clutch sleeve 58 is arranged such that the second sun gear 32 and the second planet carrier 51 are connected to each other, the second sun gear 32 and the second planet carrier 51 cannot rotate relative to each other. The second planet carrier 51 and the first sun gear 32 will therefore rotate at the same rotational speed.

[0055] Preferably, the first and second clutch bushings 56, 58 have a splined bushing that is axially slidable on splined portions of the first and second planetary gear carriers 50, 51 and on splined portions of the respective sun gears 26, 32.

[0056] The first and second clutch bushings 56, 58 according to this embodiment are arranged between the first sun gear 26 and the first planetary gear carrier 50, and between the second sun gear 58 and the second planetary gear carrier 51. However, it is also possible to arrange an additional or differently arranged clutch bushing (not shown) between the first gear ring 22 and the first planetary gear carrier 50, and a further or differently designed clutch sleeve (not shown) between the second gear ring 28 and the second planetary gear carrier 51.

[0057] In this embodiment, the first planetary gear carrier 50 in the first planetary gear 10 is fixedly connected to the second sun gear 32 of the second planetary gear 12.

[0058] The first gear pair G1 can have a first pinion 62 and a first pinion 64, which mesh with each other. The first pinion 62 can be arranged on the first main shaft 34, and the first pinion 64 can be arranged on the intermediate shaft 18. The auxiliary pinion 122 on the auxiliary shaft (secondary shaft) 120 can be engaged with the first pinion 62 on the first main shaft 34. The second gear pair G2 has a second pinion 68 and a second pinion 70, which mesh with each other. The second pinion 68 can be arranged on the second main shaft 36, and the second pinion 70 can be arranged on the intermediate shaft 18. The transmission 2 can further have a third gear pair G3, which is connected to the first main shaft 34 and the intermediate shaft 18. The third gear pair G3 has a third pinion 74 and a third pinion 76 which mesh with each other.The third pinion 74 can be mounted on the first main shaft 34, and the third pinion 76 can be mounted on the intermediate shaft 18. The transmission 2 can further include a fourth gear pair G4 connected to the second main shaft 36 and the intermediate shaft 18. The fourth gear pair G4 has a fourth pinion 80 and a fourth pinion 82 that mesh with each other. The fourth pinion 80 can be mounted on the second main shaft 36, and the fourth pinion 82 can be mounted on the intermediate shaft 18.

[0059] The first and third pinions 62, 74 may be fixedly connected to the first main shaft 34 such that they cannot rotate relative to the first main shaft 34. The second and fourth pinions 68, 80 may be fixedly connected to the second main shaft 36 such that they cannot rotate relative to the second main shaft 36.

[0060] The first, second, third, and fourth pinions 64, 70, 76, 82 may be individually removable from and mountable on the intermediate shaft 18 by means of third and fourth coupling bushings 83, 85. The coupling bushings 83, 85 may each include coupling bushings configured for mechanical engagement with splined portions on the pinions 64, 70, 76, 82 and the intermediate shaft 18. The first and third pinions 64, 76 may be connected / disconnected with a common coupling bushing 38, and the second and fourth pinions 70, 82 may be connected / disconnected with a common coupling bushing 85. In the disconnected state, relative rotation may occur between the pinions 64, 70, 76, 82 and the intermediate shaft 18. When connected, the pinion gears 64, 70, 76, 82 rotate together with the intermediate shaft 18.

[0061] The transmission 2 further has a fifth gear pair G5. The fifth gear pair G5 has a fifth pinion 92 on the intermediate shaft 18 and a fifth pinion 94 on the output shaft 20. The intermediate shaft 18 is connected to the output shaft 20 via the fifth gear pair G5. The fifth pinion 92 is arranged to be connectable to and separable from the intermediate shaft 18 by means of a fifth clutch sleeve 87. The fifth clutch sleeve 87 may have a clutch sleeve configured to engage splined portions on the fifth pinion 94 and the intermediate shaft 18. In the separated state, relative rotation can occur between the fifth pinion 92 and the intermediate shaft 18.

[0062] Drive torque can be transmitted from the input shaft 8 of the transmission 2 to the output shaft 20 of the transmission 2 via the first or second planetary gear set 10, 12 and the intermediate shaft 18. Torque can also be transmitted directly via the first planetary gear set 10 and the first main shaft 34 to the output shaft 20 via a clutch mechanism 100. The clutch mechanism 100 can include a splined clutch sleeve that is axially displaceable on the first main shaft 34 and on splined portions of the output shaft 20. By displacing the clutch sleeve 100 such that the first main shaft 34 is connected to the output shaft 20, the first main shaft 34 and the output shaft 20 have the same rotational speed.By separating the fifth pinion gear 92 from the intermediate shaft 18, torque can be transmitted from the second planetary gear 12 to the intermediate shaft 18, from the intermediate shaft 18 to the first main shaft 34, and finally via the clutch mechanism 100 to the output shaft 20.

[0063] During operation, the transmission 2 may operate in some operating states such that one of the sun gears 26, 32 is connected to the first and second planetary gear carriers 50, 51 by means of first and second coupling sleeves 56, 58, respectively.

[0064] The first and second main shafts 34, 36 can then assume the same rotational speed as the input shaft 8 of the transmission 2. One or both electric machines 14, 16 can operate as a generator to generate electrical energy for an energy storage device. Alternatively, the electric machines 14, 16 can provide additional torque to increase the torque at the output shaft 20.

[0065] It is also possible for both electric motors 14, 16 to generate energy for the energy storage device. During engine braking, the driver releases the accelerator pedal (not shown) of the vehicle 1. The output shaft 20 of the transmission 2 then actuates one or both electric motors 14, 16 in the engine braking state of the combustion engine 4 and the electric motors 14, 16. This operating state is referred to as "regenerative braking."

[0066] The drive train 3 further includes a control device 48. The control device 48 can be implemented as a separate device or it can be distributed across two or more individual devices. The control device 48 can comprise one or more control units and / or computers. The control device 48 can thus be implemented or realized by a processor and a memory, wherein the memory contains instructions that, when executed by the processor, cause the control device 48 to execute the method steps described herein.The control device 48 may thus be configured to determine a required braking force at the output shaft to maintain or reduce the speed of the vehicle; to determine that the first and second planetary gears are unlocked and switched to a neutral position; to control, by means of at least one of the first and second electric machines, the internal combustion engine to a rotational speed at which the engine braking force corresponds to the determined braking force; and to control the internal combustion engine into an engine braking mode.

[0067] The control device 48 is connected to the electric machines 14, 16 in order to control them, respectively. The control device 48 can be configured to collect information from the components of the drive train 3 and, based on this information, to control the electric machines 14, 16 such that they operate as electric motors or as generators. The control device 48 can be a computer with software suitable for this purpose. The control device 48 can also be connected to the first and second clutch bushings 56, 58, the third and fourth clutch bushings 83, 85, and the clutch bushing 100. These components are preferably activated and deactivated by electrical signals from the control device 48.

[0068] The example according to Fig. 2 shows four gear pairs G1, G2, G3, G4 and two planetary gears 10, 12 with associated electric machines 14, 16. However, it is also possible to provide the gear 2 with more or fewer pinions and cog wheels and with more planetary gears, each with associated electric machines.

[0069] At least one sensor 62 may be connected to the control device 48. The sensor may be a speed sensor, a weight sensor, a position sensor, and / or an inclination sensor.

[0070] Fig. 3 shows a diagram according to an embodiment. The diagram shows the braking torque T and the braking force P generated at different rotation speeds of the internal combustion engine. The braking torque T from the internal combustion engine is shown with a dashed line, and the braking force P from the internal combustion engine is shown as a solid line. The braking torque T and the braking force P are generated by the internal combustion engine at the output shaft of the internal combustion engine. The output shaft of the internal combustion engine is connected to the crankshaft of the internal combustion engine. The diagram shows that both the braking torque T and the braking force P increase with the rotation speed of the internal combustion engine.The different values ​​regarding braking torque T and braking force P, as generated at different rotation speeds of the internal combustion engine, can be stored in a memory of the vehicle, such as in a memory of the control device.

[0071] Fig. 4 shows a flowchart for a method for controlling the braking of a vehicle 1 according to an embodiment. The vehicle 1 can Fig. 1. The drive train 3 can be configured accordingly Fig. 2, Fig. 3 and Fig. 4. Thus, the vehicle 1 can comprise: an internal combustion engine 4, a first electric machine 14, a second electric machine 16, and a transmission 2. The transmission 2 comprises: an input shaft 8; a first main shaft 34; a second main shaft 36; an output shaft 20 connected to drive wheels 6 of the vehicle; an intermediate shaft 18 connected to the first main shaft 34, the second main shaft 36, and the output shaft; a first gear pair G1 connected to the first main shaft 34 and the intermediate shaft 18; a second gear pair G2 connected to the second main shaft 36 and the intermediate shaft 18; a first planetary gear 10 connected to the input shaft 8 and the first main shaft 34; a second planetary gear 12 connected to the first planetary gear 10 and the second main shaft 36;wherein the internal combustion engine 4 is connected to the input shaft 8, the first electric machine 14 is connected to the first planetary gear 10, and the second electric machine 16 is connected to the second planetary gear 12 such that drive torque can be applied to the first main shaft 34 and the second main shaft 36 by means of the internal combustion engine 4, the first electric machine 14, and the second electric machine 16, the method comprising: a determination s101 of a required braking force on the output shaft 20 for maintaining or reducing the speed of the vehicle 1; a determination s102 that the first and second planetary gears 10, 12 are unlocked and placed in a neutral position; a control s103 of the internal combustion engine 4 by means of at least one of the first and second electric machines 14, 16 to a rotation speed at which an engine braking force is generated corresponding to the determined braking force;and controlling s104 the internal combustion engine 4 into an engine braking state.;

[0072] The step of determining s101 a required braking force on the output shaft to maintain or reduce the speed of the vehicle 1 includes a determination of the weight, speed and air resistance of the vehicle 1 as well as the inclination of the vehicle in the longitudinal direction.

[0073] The step of determining s102 that the first and second planetary gear sets 10, 12 are unlocked and placed in a neutral position includes determining that a first axially movable clutch sleeve 56 has separated a first sun gear (central pinion) 26 from a first planetary gear carrier 50 of the first planetary gear set 10, and that a second axially movable clutch sleeve 58 has separated a second sun gear 32 from a second planetary gear carrier 51 of the second planetary gear set 12.

[0074] The control step s103 includes controlling, by means of at least one of the first and second electric machines 14, 16, the internal combustion engine 4 to a rotational speed at which an engine braking force acts in accordance with the determined braking force, wherein the internal combustion engine 4 is controlled to a rotational speed independent of the speed of the first and second main shafts 34, 36 in the transmission 2.

[0075] The step s104 of controlling the internal combustion engine 4 into an engine braking mode may include controlling an exhaust brake 60 of the internal combustion engine 4.

[0076] The method includes the further step of controlling s105 at least one of the first and second electric machines 14, 16 to generate additional braking force on the output shaft 20.

[0077] The step s105 of controlling at least one of the first and second electric machines 14, 16 to generate additional braking force on the output shaft 20 may include a control in which at least one of the first and second electric machines 14, 16 is placed in a generator mode.

[0078] Fig. 5 schematically shows an embodiment of a device 500. The control device 48 according to the Fig.2 to 4, one version of the device 500 may include a non-volatile memory 520, a data processing unit 510, and a read / write memory 550. The non-volatile memory 520 has a first memory area 530 in which a computer program, e.g., an operating system, is stored for controlling the functions of the device 500. The device 500 may further include a bus controller, a serial communication port, input / output devices, an analog / digital converter, a time and date transmission unit, an event counter, and an interrupt controller (not shown). The non-volatile memory 520 further includes a second memory area 540.

[0079] A computer program P is provided which has routines for controlling the braking of the vehicle. The computer program P further has routines for determining the load on an auxiliary shaft by detecting a condition in which matching gear teeth of a first gear pair move within a gear backlash of the first gear pair, wherein the drive torque on the first main shaft corresponds to the load on the auxiliary shaft. The program P can be stored in executable form or in compressed form in a memory 560 and / or in a read / write memory 550.

[0080] If the data processing unit 510 executes a specific function, this means that the data processing unit 510 executes a specific part of the program stored in the memory 560 or a specific part of the program stored in the read / write memory 550.

[0081] The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is used for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is used for communication with the data processing unit 510 via a data bus 511. The read / write memory 550 is configured for communication with the data processing unit 510 via a data bus 514.

[0082] If data is received at the data port 599, it is temporarily stored in the second memory area 540. Once the received data is temporarily stored, the data processing unit 510 can implement the program as described above.

[0083] Parts of the methods described here can be executed with the device 500 by means of the data processing unit 510, which executes the program stored in the memory 560 or the program stored in the read / write memory 550. If the device 500 executes the program, the methods described here are executed.

[0084] The above description of preferred embodiments of the invention is for illustrative purposes only. It is not intended to be exhaustive or to limit the invention to the described variants. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in detail in order to best explain the principles of the invention and their practical applications so that those skilled in the art will understand and practice the invention, with modifications as appropriate.

Claims

[1] Method, carried out by a control device (48), for controlling the braking of a vehicle (1) which has an internal combustion engine (4), a first electric machine (14), a second electric machine (16) and a transmission (2), wherein the transmission (2) comprises: an input shaft (8); a first main shaft (34); a second main shaft (36); an output shaft (20) connected to drive wheels (6) of the vehicle (1); an intermediate shaft (18) connected to the first main shaft (34), the second main shaft (36) and the output shaft (20); a first gear pair (G1) connected to the first main shaft (34) and the intermediate shaft (18); a second gear pair (G2) which is connected to the second main shaft (36) and the intermediate shaft (18); a first planetary gear (10) connected to the input shaft (8) and the first main shaft (34); and a second planetary gear (12) connected to the first planetary gear (10) and the second main shaft (36); wherein the internal combustion engine (4) is connected to the input shaft (8), the first electric machine (14) is connected to the first planetary gear (10), and the second electric machine (16) is connected to the second planetary gear (12) such that drive torque can be applied to the first main shaft (34) and the second main shaft (36) by means of the internal combustion engine (4), the first electric machine (14), and the second electric machine (16), the method comprising: a determination (s101) of a required braking force on the output shaft (20) to maintain or reduce the speed of the vehicle (1); a determination (s102) that the first and second planetary gears (10; 12) are unlocked and brought into a neutral position; controlling (s103) the internal combustion engine (4) by means of at least one of the first and second electric machines (14, 16) to a rotational speed at which an engine braking force corresponds to the determined braking force; and a control (s104) of the combustion engine (4) in an engine braking mode. [2] Method according to claim 1, wherein the determination (s101) of a required braking force on the output shaft (20) for maintaining or reducing the speed of the vehicle (1) includes a determination of the weight, the speed and the air resistance of the vehicle (1) as well as the inclination of the longitudinal axis of the vehicle (1). [3] Method according to one of claims 1 or 2, wherein the determination (s102) that the first and second planetary gears (10; 12) are unlocked and brought into a neutral position includes a determination that a first axially displaceable clutch sleeve (56) separates a first sun gear (26) from a first planet gear carrier (50) of the first planetary gear (10) and that a second axially displaceable clutch sleeve (58) separates a second sun gear (32) from a second planet gear carrier (51) of the second planetary gear (12). [4] Method according to one of the preceding claims, wherein the control (s103) of the internal combustion engine (4) by means of at least one of the first and second electric machines (14, 16) to a rotational speed at which the engine braking force corresponds to the determined braking force includes controlling the internal combustion engine (4) to a rotational speed, independent of the speed of the first and second main shafts (34, 36) in the transmission (2). [5] Method according to one of the preceding claims, wherein the control (s104) of the internal combustion engine (4) in an engine braking mode includes a control of an exhaust brake (60) of the internal combustion engine (4). [6] A method according to any one of the preceding claims, wherein the method comprises the further step of: a controller (s105) of at least one of the first and second electric machines (14, 16) for generating additional braking force on the output shaft (20). [7] The method of claim 6, wherein the control (s105) of at least one of the first and second electrical machines (14, 16) to generate additional braking force at the output shaft (20) includes controlling at least one of the first and second electrical machines (14, 16) into a generator mode. [8] A computer program (P) comprising instructions which, when executed by a computer (48; 500), cause the computer (48; 500) to carry out a method according to any one of the preceding claims. [9] A computer-readable medium having instructions which, when executed by a computer (48; 500), cause the computer (48; 500) to perform a method according to any one of claims 1 to 7. [10] Vehicle (1), comprising: an internal combustion engine (4); a first electrical machine (14); a second electric machine (16); a gearbox (2); and a control device (48), wherein the transmission (2) comprises: an input shaft (8); a first main shaft (34); a second main shaft (36); an output shaft (20) connected to drive wheels (6) of the vehicle (1); an intermediate shaft (18) connected to the first main shaft (34), the second main shaft (36) and the output shaft (20); a first gear pair (G1) connected to the first main shaft (34) and the intermediate shaft (18); a second gear pair (G2) which is connected to the second main shaft (36) and the intermediate shaft (18); a first planetary gear (10) connected to the input shaft (8) and the first main shaft (34); and a second planetary gear (12) connected to the first planetary gear (10) and the second main shaft (36); wherein the internal combustion engine (4) is connected to the input shaft (8), the first electric machine (14) is connected to the first planetary gear (10), and the second electric machine (16) is connected to the second planetary gear (12), so that drive torque can be applied to the first main shaft (34) and the second main shaft (36) by means of the internal combustion engine (4), the first electric machine (14), and the second electric machine (16), wherein the control device (48) is configured to: Determining a braking force required at the output shaft (20) to maintain or reduce the speed of the vehicle (1); Determining that the first and second planetary gears (10; 12) are unlocked and brought into a neutral position; Controlling the internal combustion engine (4) by means of at least one of the first and second electric machines (14, 16) to a rotational speed at which engine braking force acts in accordance with the determined braking force; and Controlling the combustion engine (4) into an engine braking mode. [11] Vehicle (1) according to claim 10, wherein the control device (48) is arranged to determine the weight, the speed and the air resistance of the vehicle (1) as well as the inclination in the longitudinal direction of the vehicle (1). [12] Vehicle (1) according to one of claims 10 and 11, wherein the control device (48) is arranged to determine whether a first axially displaceable coupling bushing (56) has separated a first sun gear (26) from a first planet gear carrier (50) of the first planetary gear (10) and whether a second axially displaceable coupling bushing (58) has separated a second sun gear (32) from a second planet gear carrier (51) of the second planetary gear (12). [13] Vehicle (1) according to one of claims 10 to 12, wherein the control device (48) is arranged to control the internal combustion engine (4) to a rotational speed independent of the speed of the first and second main shafts (34, 36) in the transmission (2). [14] Vehicle (1) according to one of claims 11 to 13, wherein the control device (48) is arranged to control an exhaust brake (60) of the internal combustion engine (4). [15] Vehicle (1) according to one of claims 11 to 14, wherein the control device (48) is further arranged to: to control at least one of the first and second electrical machines (14, 16) to generate an additional braking force on the output shaft (20). [16] Vehicle (1) according to claim 15, wherein the control device (48) is arranged to control at least one of the first and second electrical machines (14, 16) into a generator mode.

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