Transmission arrangement for a hybrid drive of a motor vehicle

Abstract

Transmission arrangement for a hybrid drive of a motor vehicle, in particular a commercial vehicle, comprising a manual transmission (1, 11), in particular a range transmission (1, 11) with an output side (1b), an output flange (2) and a countershaft (VW, VW1, VW2), wherein an auxiliary transmission (3, 13, 23) with at least one electric machine (EM, EM1, EM2) and at least one transmission stage (Ü1, Ü2, Ü3) is arranged on the manual transmission (1, 11), wherein the at least one electric machine (EM, EM1, EM2) is connected to the countershaft (VW) via the at least one transmission stage (Ü1, Ü2) and can be engaged as an additional electric drive or output, characterized in that two electric machines (EM1, EM2) are attached to the auxiliary transmission (13, 23).

Description

[0001] The invention relates to a transmission arrangement for a hybrid drive of a motor vehicle, in particular a commercial vehicle, comprising a manual transmission, in particular a group transmission with an output side, an output flange and at least one countershaft.

[0002] DE 10 2016 218 361 A1 discloses a hybridized motor vehicle transmission designed as a group transmission with a main and a range-change group. It has an electric motor on its input or drive side, which can be coupled to the main group of the group transmission via a planetary gear set. The electric motor and the planetary gear set are arranged coaxially with the input shaft of the main group. The main group has two countershafts, each with five fixed gears, which mesh with idler gears on the input shaft. The range-change group arranged on the output side is designed as a planetary gear.

[0003] WO 2016 / 046 001 A1 discloses a drive arrangement with a first and a second drive unit, each with a gear assembly and an output unit. The two gear assemblies can be connected in a force-locking and / or form-locking manner.

[0004] The publication DE 10 2013 223 462 A1 shows a motor vehicle transmission for a drive train of a hybrid vehicle, comprising two sub-transmissions, each with a transmission input shaft and a common transmission output. The transmission input shaft of one of the sub-transmissions serves to connect an internal combustion engine. Furthermore, a first sub-transmission is designed as a spur gear transmission with multiple spur gear stages, and a superposition stage is provided, via which the operation of the internal combustion engine can be superimposed on the operation of an electric motor.

[0005] DE 199 81 968 B4 describes a transmission having a transmission input shaft and a transmission output shaft drivable by an internal combustion engine and having a plurality of gear pairs, and having an electric machine, wherein the electric machine is connectable to the output shaft of the transmission by means of a first clutch and is connectable to the input shaft of the transmission by means of a second clutch.

[0006] DE 10 2015 224 208 B3 states that drive torque from traction motors is transmitted to the vehicle's driven wheels via a drivetrain. Integrated into the drivetrain are transmission structures that allow the vehicle to be driven either exclusively with the electric motor, exclusively with the combustion engine, or by utilizing the traction torque from both motors.

[0007] Starting from a conventional drive with an internal combustion engine and a multi-speed manual transmission, it is an object of the present invention to retrofit the conventional drive to a hybrid drive.

[0008] The invention comprises the features of patent claim 1. Advantageous embodiments emerge from the subclaims.

[0009] According to the invention, an add-on gearbox with at least one electric motor and at least one gear ratio is arranged on a known manual transmission, in particular a group transmission for commercial vehicles, wherein the at least one electric motor is connected to the countershaft of the manual transmission via the at least one gear ratio and can be switched on as an additional electric drive. This has the advantage that a conventional drive of a motor vehicle with an internal combustion engine can be upgraded to a hybrid drive by the subsequent or optional installation of a hybrid module. The electric motor is preferably designed for operation below the low voltage limit (48 volts) and is therefore cost-effective. Only a few changes need to be made to the existing commercial vehicle transmission so that the add-on gearbox with the electric motor(s), ieThe hybrid module can be mounted on the manual transmission. The hybrid module can be removed again if there is no longer any need for a hybrid drive.

[0010] According to a preferred embodiment, the hybrid module is arranged on the rear or output side of the manual transmission, next to the output flange. It is advantageous that the transmission is not extended, or only extended as little as possible, in the relevant length of the engine / output flange by mounting it parallel to the drive shaft.

[0011] According to a further preferred embodiment, at least one clutch, preferably a dog clutch, is arranged in the power flow between the at least one electric motor and the countershaft, via which the electric drive can be engaged or disengaged. The electric motor drives the countershaft via a gear ratio, from which the power flows to the transmission output shaft. This means that the power of the combustion engine and the power of the electric motor are available at the wear flange of the manual transmission. However, it is also possible to switch off the combustion engine and drive purely electrically. Furthermore, electrical energy can be obtained from the kinetic energy of the vehicle or the combustion engine to operate the auxiliary units or for storage.

[0012] According to the invention, two electric motors are attached to the add-on gearbox, with either an axially parallel arrangement or a coaxial arrangement on opposite sides of the add-on gearbox being possible. The different arrangements of the electric motors also depend on the installation options in the vehicle. The larger amount of available electrical energy reduces fuel consumption more significantly and allows the internal combustion engine to be switched off and restarted while driving.

[0013] According to a further preferred embodiment, the electric motor is assigned an auxiliary transmission with a first or a second planetary gear set, each of which has a sun gear shaft, a ring gear shaft, and a carrier shaft. This offers the advantage that the input and output of the planetary gear set can be arranged coaxially and on the same side, namely the side of the auxiliary transmission adjacent to the auxiliary transmission. With the gear ratio of the planetary gear set of the auxiliary transmission, the switched-off combustion engine can be restarted by an electric motor.

[0014] According to a further preferred embodiment, the first planetary gear set is shiftable, with a first gear being shiftable by holding the ring gear shaft in place, and a second gear being shiftable by interlocking the sun gear shaft with the ring gear shaft. Interlocking means that the sun gear shaft and the ring gear shaft are coupled together and rotate as a single unit. This allows for both a slow gear ratio and a through drive (1:1 ratio). In single unit rotation, the electric motor operates in the optimal efficiency range without additional losses in the planetary gear. The additional ratio of the planetary gear is activated for the very short time required for the engine restart.

[0015] According to a further preferred embodiment, the planetary gear set of the auxiliary transmission has a freewheel and a single gear ratio with a single shift point for restarting the combustion engine. This reduces the operating effort. The sun gear shaft is driven by the electric motor, while the ring gear shaft drives a gear of the gear ratio stage. The planetary gear shaft is blocked by a freewheel when the electric motor starts the combustion engine, with the electric motor running in reverse, i.e., rotating in the opposite direction to that in hybrid operation.

[0016] According to another preferred embodiment, a refrigerant compressor of an on-board air conditioning system, also called a compressor, is assigned to the add-on gearbox. The compressor is driven via an additional gear ratio of the add-on gearbox. By decoupling the hybrid module from the countershaft, air conditioning can be provided by the electric motor when stationary. While driving, energy can be drawn either from the vehicle or from the combustion engine.

[0017] According to a further preferred embodiment, the gear ratios of the add-on transmission are designed as spur gear stages, with the spur gears preferably arranged in one plane. This results in a narrow add-on transmission, viewed in the axial direction of the manual transmission, whose housing serves as the carrier for at least one electric motor, the additional transmission, the compressor, and optionally other auxiliary units.

[0018] Embodiments of the invention are illustrated in the drawings and are described in more detail below, whereby further features and / or advantages may emerge from the description and / or the drawings. Fig. 1 a 3D representation of a commercial vehicle transmission with an add-on transmission according to the invention, an electric motor and an air conditioning compressor, arranged on the output side of the transmission, Fig. 2 a schematic representation of the commercial vehicle transmission with add-on gearbox, electric motor, an additional gearbox and air conditioning compressor, Fig. 3 shows a further embodiment of the invention with two electric machines arranged coaxially and diametrically to each other on the add-on gearbox and Fig. 4 a further embodiment of the invention with two electric machines arranged axially parallel on the add-on gearbox and a further embodiment of the additional gearbox.

[0019] Fig. 1 shows a manual transmission 1 for commercial vehicles with a front or drive side 1a and a rear or output side 1b in a 3D representation with a view of the output side 1b. The manual transmission 1, which is preferably used for commercial vehicles, corresponds to the known prior art and has an output flange 2 on its output side 1b. According to the invention, an add-on transmission 3 is arranged on the rear side 1b of the manual transmission 1, to which an electric motor EM, a compressor 4 of an air conditioning system, also called a refrigerant compressor 4, and an additional transmission 5 are fastened. The add-on transmission 3 with electric motor EM, compressor 4 and additional transmission 5 forms a hybrid module, which is arranged laterally of the output flange 2. A transmission control device 6, which will be discussed in more detail later, is fastened on the top side of the housing of the manual transmission 1.

[0020] Fig. 2 shows the manual transmission 1 with add-on transmission 3, electric motor EM, compressor 4 and additional transmission 5 according to Fig. 1 in a schematic representation. The same reference numerals are used for identical parts. The manual transmission 1 is designed as a group transmission and has five gear planes R1, R2, R3, R4, R5, whereby the gear planes R1, R2 form a splitter group and the gear planes R3, R4, R5 form a main group; a switchable planetary gear PG forms a range group. Thus, twelve gears can be switched. The manual transmission 1 has an input shaft EW, a main shaft HW, and two countershafts VW1, VW2. The first countershaft VW1 is coupled to an intermediate shaft ZW, which in the prior art serves to drive an auxiliary unit and is also referred to as a PTO (Power Take Off) shaft. In the present case, the intermediate shaft ZW or the first countershaft VW1 serves as the connecting shaft to the auxiliary transmission 3.The add-on gearbox 3 has three gears arranged in one plane: a first gear Z1 on the axis of the countershaft VW1, a second gear Z2 on the axis of the electric motor EM, and a third gear Z3 on the axis of the compressor 4. The gears Z1, Z2 form a first gear ratio Ü1 between the electric motor EM and the countershaft VW1, and the gears Z1, Z3 form a second gear ratio Ü2 between the compressor 4 and the countershaft VW1. The first gear Z1 is rotatably (“loosely”) arranged on the intermediate shaft ZW and can be coupled to the intermediate shaft ZW by a clutch 7, in particular a dog clutch 7. The additional gearbox 5 has a first planetary gear set PS1, also called planetary gear set PS1 for short, which is arranged coaxially to the axis of rotation of the electric motor EM.The rotor shaft of the electric motor EM drives the sun gear SO1 of the first planetary gear set PS1. The output of the first planetary gear set PS1 is transmitted via the carrier shaft ST1 to the second gear Z2. The first planetary gear set PS1 is shiftable, with a first gear being engaged by holding the ring gear shaft HR1 in place, and a second gear being engaged by locking the sun gear SO1 to the ring gear shaft HR1.

[0021] The function of the hybrid module described above, which comprises at least the add-on gearbox 3 and an electric motor EM and optionally the additional gearbox 5, is to provide an additional electric drive for the conventional drive of a commercial vehicle, i.e. an internal combustion engine with the manual gearbox 1; in other words: the conventional internal combustion engine drive is to be upgraded and retrofitted to a hybrid drive, i.e. hybridized. The power flow from the electric motor EM to the manual gearbox 1 occurs via the intermediate shaft ZW and the first countershaft VW1. In the case of an additional electric drive by the electric motor EM (hybrid operation), the first planetary gear set PS1 is blocked, i.e. there is a gear ratio of 1:1 between the rotor or sun shaft SO1 and the planetary shaft ST1.The carrier shaft ST1 drives the second gear Z2, which meshes with the first gear Z1 and forms the first gear ratio Ü1 (downward). The gear ratio is adapted to the vehicle's most frequently driven speed range, so that the electric motor EM can operate at its most efficient level in this range. When the manual transmission 1 is electrically driven, the clutch 7 is engaged. At the same time, the compressor 4 is driven via the second gear ratio Ü2. In hybrid operation, the combined power of the combustion engine and the electric motor EM is delivered to the wear flange 2.

[0022] Outside of hybrid mode, i.e., when the combustion engine is switched off, the electric motor EM can also be used in conjunction with the auxiliary transmission 5 as a starter motor for the combustion engine. For this purpose, the ring gear HR1 of the first planetary gear set PS1 is braked, resulting in a slow gear ratio between the sun gear SO1, driven by the electric motor EM, and the output planetary gear ST1. This provides a sufficiently high torque at the input shaft EW of the manual transmission 1 to restart the combustion engine.

[0023] Fig. 3 shows a further embodiment of the invention for a hybridized manual transmission 11, wherein the same reference numerals increased by 10 are used for the same parts. The manual transmission 11 in Fig. 3 has only one countershaft VW, which is coupled to the intermediate shaft ZW. The add-on gearbox 13 has three gears, a first gear Z1, a second gear Z2 and a third gear Z3, which are arranged in one plane and are designed as spur gears. A first electric machine EM1 and a second electric machine EM2 are arranged coaxially to one another on either side of the add-on gearbox 13 and are connected to the second gear Z2. A compressor 14 is driven by the third gear Z3, which meshes with the second gear Z2. The first gear Z1 is rotatably arranged on the intermediate shaft ZW, which extends out of the housing of the manual transmission 11 and into the add-on gearbox 13, i.e. is designed as an idler gear - the idler gear Z1 can be connected in a rotationally fixed manner to the intermediate shaft ZW or the countershaft VW by the clutch 17.Due to the two electric machines EM1, EM2, the provided electric drive power is significantly increased.

[0024] Fig. 4 shows, as a further embodiment of the invention, an add-on gearbox 23 with two electric motors EM1, EM2 arranged axially parallel to one another and an additional gearbox 25, which has a second planetary gear set PS2 with a freewheel 26. The gearbox is in Fig. 4 has been omitted; instead, only the countershaft VW is shown, which is connected in a rotationally fixed manner to the first gear Z1. The add-on gearbox 23 has a total of four gears Z1, Z2, Z3, Z4 arranged in one plane: A second gear Z2, coaxial with the first electric machine EM1, and a fourth gear Z4, coaxial with the second electric machine EM2, both mesh with the first gear Z1 and form a first gear ratio Ü1 between the first electric machine EM1 and the countershaft VW, as well as a second gear ratio Ü2 between the second electric machine EM2 and the countershaft VW. A third gear Z3 is arranged coaxially with the axis of rotation of the compressor 24 and, together with the second gear Z2, forms a third gear ratio Ü3. The two electric machines EM1, EM2 are each arranged on the rear of the add-on gearbox 23 and can each be engaged via a clutch 27, 28.The second planetary gear set PS2, arranged coaxially with the first electric motor EM1, has a sun gear shaft SO2, which is driven by the rotor shaft of the first electric motor EM1, and a ring gear shaft HR2, which forms the output shaft and is connected to the second gear Z2. The planetary gear shaft ST2 is freely rotatable in the main direction of rotation, i.e., in hybrid mode; in the reverse direction of rotation, the planetary gear shaft ST2 is blocked by the freewheel 26.

[0025] The function of the above-described arrangement with two electric motors EM1, EM2 is as follows: In hybrid mode, the two electric motors EM1, EM2 can be engaged together or individually, depending on the power requirement. For this purpose, the rotor shafts are coupled to the second gear Z2 and the fourth gear Z4, respectively, via the clutches 27, 28. Both gears Z2, Z4 mesh with the first gear Z1 and thus drive the countershaft VW.

[0026] The first electric motor EM1, in conjunction with the auxiliary transmission 25, can also be used to restart the internal combustion engine if it has been shut down. During a restart, the first electric motor EM1 rotates in the opposite direction and drives the second planetary gear set PS2 via the sun gear shaft SO2, with the planetary gear shaft ST2 blocked by the freewheel 26. This results in a gear ratio between the driven sun gear shaft SO2 and the driven ring gear shaft HR2 that is at a low speed. Accordingly, a sufficiently high torque is available at the countershaft VW to restart the internal combustion engine.

[0027] The hybrid strategy and the control of the electric motors EM1, EM2 and the clutches 27, 28 are carried out by the transmission control unit 6 mentioned above ( Fig.1). The hybrid module described above was presented as an example for retrofitting to known manual transmissions with at least one countershaft. However, it is also possible to install the hybrid module according to the invention described above on other transmission types that have an engine-side intermediate or PTO shaft. Furthermore, the electric motor EM can support and accelerate the shifting process through suitable control. This means that a transmission brake can be omitted if necessary, or synchronization can be replaced by a simple positive-locking shifting element. The hybrid module according to the invention also allows the drive of auxiliary units when the combustion engine is switched off, which is particularly advantageous for air conditioning in the vehicle cabin.

[0028] The electric machines EM, EM1, EM2 are preferably designed for alternating current below the low voltage limit of approximately 50 volts. Reference symbol 1 manual transmission 1a Drive side 1b Output side 2 Output flange 3 add-on gearboxes 4 Compressor 5 additional gears 6 Transmission control unit 7 clutch 11 manual transmissions 13 add-on gearboxes 14 Compressor 17 Clutch 23 add-on gearboxes 24 compressor 25 additional gears 26 Freewheel 27 Clutch (EM1) 28 Clutch (EM2) EM electric machine EM1 first electric machine EM2 second electric machine EW input shaft HW main shaft HR1 ring gear shaft (PS1) HR2 ring gear shaft (PS2) PG planetary gear PS1 first planetary gear set PS2 second planetary gear set R1 first wheel level R2 second wheel plane R3 third wheel plane R4 fourth wheel plane R5 fifth wheel level SO1 Sunwave (PS1) SO2 solar wave (PS2) ST1 web wave (PS1) ST2 web wave (PS2) Ü1 first translation level Ü2 second translation level Ü3 third translation level VW countershaft VW1 first countershaft VW2 second countershaft Z1 first gear Z2 second gear Z3 third gear Z4 fourth gear

Claims

[1] Gearbox arrangement for a hybrid drive of a motor vehicle, in particular a commercial vehicle, comprising a manual transmission (1, 11), in particular a group transmission (1, 11) with an output side (1b), an output flange (2) and a countershaft (VW, VW1, VW2), wherein an add-on transmission (3, 13, 23) with at least one electric machine (EM, EM1, EM2) and at least one transmission stage (Ü1, Ü2, Ü3) is arranged on the manual transmission (1, 11), wherein the at least one electric machine (EM, EM1, EM2) is connected to the countershaft (VW) via the at least one transmission stage (Ü1, Ü2) and can be connected as an additional electric drive or output, characterized by that two electric machines (EM1, EM2) are attached to the add-on gearbox (13, 23). [2] Gear arrangement according to claim 1, characterized by that the add-on gear (3, 13, 23) is arranged on the output side (1b) of the gearbox (1, 11). [3] Gear arrangement according to claim 1 or 2, characterized by that the at least one electric machine (EM, EM1, EM2) can be connected or disconnected via at least one clutch (7, 17, 27, 28) which is arranged in the power flow between the at least one electric machine (EM, EM1, EM2) and the countershaft (VW). [4] Gear arrangement according to one of the preceding claims, characterized by that the two electric machines (EM1, EM2) are arranged axially parallel to each other and are connected to the countershaft (VW) by gear ratios (Ü1, Ü2). [5] Gear arrangement according to one of the preceding claims, characterized by that the two electric machines (EM1, EM2) are arranged on opposite sides of the add-on gearbox (13) and coaxially to each other. [6] Gear arrangement according to one of claims 1 to 5, characterized bythat the at least one electric machine (EM, EM1) is assigned an additional transmission (5, 25) with a first or second planetary gear set (PS1, PS2) each having a sun shaft (SO1, SO2), a ring gear shaft (HR1, HR2) and a carrier shaft (ST1, ST2). [7] Gear arrangement according to claim 6, characterized by that the first planetary gear set (PS1) is switchable, whereby a first gear can be switched by holding the ring gear shaft (HR1) and a second gear can be switched by blocking the sun shaft (SO1) with the ring gear shaft (HR1). [8] Gear arrangement according to claim 6, characterized by that the second planetary gear set (PS2) has a freewheel (26), that the sun shaft (SO2) forms the input shaft and the ring gear shaft (HR2) forms the output shaft and that the carrier shaft (ST2) can be blocked in one direction of rotation by the freewheel (26). [9] Gear arrangement according to one of claims 1 to 8, characterized bythat an auxiliary unit is assigned to the add-on gearbox (3, 23) and can be driven via a further transmission stage (Ü2, Ü3). [10] Gear arrangement according to claim 9, characterized by that the auxiliary unit is a refrigerant compressor (4, 24) of an air conditioning system and that the refrigerant compressor (4, 24) can be driven via the further transmission stage (Ü2, Ü3). [11] Gear arrangement according to one of claims 1 to 9, characterized by that the gear ratios (Ü1, Ü2, Ü3) are designed as spur gear stages.

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