Hybrid rear axle transmission mechanism

Abstract

The invention relates to a hybrid rear axle drive (H-HAG) with an electric torque vectoring system (eTV), a powertrain for a motor vehicle, in particular a plug-in hybrid electric vehicle (PHEV), and an electric torque vectoring method.

Description

Technical Field

[0001] This invention relates to a hybrid rear axle drivetrain (H-HAG) with an electric torque vectoring system (eTV), a powertrain for motor vehicles, particularly plug-in hybrid electric vehicles (PHEVs), and an electric torque vectoring method. Background Technology

[0002] A conventional rear axle drivetrain (HAG) with torque vectoring (TV) comprises conventional axle drivetrains arranged on the left and right sides, as well as a superimposed unit. The superimposed unit includes a superimposed drivetrain and a diaphragm clutch. With the aid of the integrated diaphragm clutch, the superimposed drivetrain can variably distribute drive power between the rear axle wheels within the system boundaries. The diaphragm clutch is operated by a hydraulic control unit. An electric motor drives an oil pump that provides the necessary hydraulic pressure. All functions are controlled and monitored by a separate controller. The superimposed drivetrain comprises two coaxially arranged hollow wheel gearboxes with one reduction stage (i1>1) and one acceleration stage (i2<1). With the aid of the superimposed drivetrain, additional torque can be engaged as the rotational speed increases, depending on the force engagement of the diaphragm clutch. Therefore, the transmitted power increases. The transmittable torque difference is related to the maximum torque that can be transmitted through the diaphragm clutch. Therefore, the structural space of the maximum diameter of the friction plate assembly also limits the maximum torque difference. Combined with high vehicle weight (e.g., in the case of PHEVs), the torque difference provided by the HAG with TV via the superimposed unit with a diaphragm clutch is insufficient to achieve the sufficiently dynamic driving performance required for sporty vehicles. This is because the increase in wheel speed that the superimposed unit with a diaphragm clutch can only provide cannot achieve stable intervention in driving dynamics (intended at corner entrances).

[0003] The hybrid dual-speed rear axle drivetrain with differential locking mechanism (H-HAG) features a conventional bevel gear differential connected to the center differential via a universal joint. Additionally, the electric motor (in the P4 arrangement) can act on the crown gear of the differential via a two-speed transmission. The bevel gear differential is implemented as a differential lock with a hydraulically operated diaphragm clutch. Combined with an additional center differential / hang-on-mitteldifferential (not part of the H-HAG) to improve driving dynamics, the differential locking mechanism can intervene stably. Therefore, driving dynamics at corner exits may be affected in the direction of dynamically perceived, over-controlled driving behavior. The implementation of the P4-motor connection to the drivetrain via a two-speed transmission requires switching on the rear axle in addition to switching in the main transmission. This causes a disruption in the traction of the P4-motor's drive torque. This additional switching on the rear axle adversely affects both vehicle comfort and dynamics. The differential lock mechanism on the rear axle always plays a stabilizing role in the dynamic performance range at corner exits in all-wheel-drive vehicles. Furthermore, an additional center differential is necessary to enable sporty driving behavior. Rapid intervention in dynamic performance can only be achieved through the variable distribution of drive torque within the additional center differential.

[0004] WO 2015 / 169 837 A1 discloses a torque vectoring device for a vehicle, the torque vectoring device including a motor connected to a differential mechanism via a transmission, wherein the torque vectoring device further includes at least one control device for changing the torque path of the transmission between a first mode and a second mode, in which the transmission connects the motor to the differential mechanism input shaft for a hybrid drive mode, and in the second mode, the transmission connects the motor to the differential mechanism output shaft for a torque vectoring mode.

[0005] DE 10 2019 129 670 A1 relates to a hybrid axle drive system with torque vectoring. The electric axle drive uses a motor to drive two half-shafts via an end-drive transmission and a differential. The torque vectoring transmission alters the torque distribution by transferring power from one half-shaft to the motor or from the motor to the half-shaft in response to brake engagement. The end-drive transmission and torque vectoring transmission are implemented using a stepped planetary gear set. The end-drive transmission and differential are located at one end of the motor. The torque vectoring transmission is located at the opposite end of the motor.

[0006] DE 10 2009 059 903 A1 discloses a system for variably distributing torque within at least one axle of a motor vehicle, the system comprising a main drive unit and a torque vectoring motor. Summary of the Invention

[0007] In this context, the object of the present invention is to provide a rear axle drive mechanism and powertrain for a plug-in hybrid electric vehicle (PHEV), which enables driving performance with high driving dynamics, especially driving performance with high driving dynamics even when cornering.

[0008] According to the invention, this objective is achieved by a product having the features of claims 1 and 7 and a method having the features of claim 10. Extensions and improvements of the invention are derived from the dependent claims, the specification, and the drawings.

[0009] According to the present invention, to further improve the performance of the PHEV powertrain, a hybrid rear axle drivetrain (H-HAG) with an electric torque vectoring system (eTV) is used. As a supplement to the conventional mechanical drive via a universal joint, a permanently connected integrated motor is used, which has a transmission for enhancing propulsion and for regeneration. Additionally, a separate motor with integrated power electronics is used, which drives the electric torque vectoring system (eTV). The eTV system is used not only to improve lateral dynamics but also to enhance driving stability. Utilizing the H-HAG, the overall system power is increased through the modular expansion of the powertrain. The H-HAG is modularly constructed and variable (the power motor and eTV system can be integrated separately).

[0010] The subject of this invention relates to a rear axle drive mechanism for motor vehicles, particularly PHEVs, the rear axle drive mechanism comprising a pinion shaft, a hollow shaft having bevel gear teeth and cylindrical gear teeth, and a differential having a cylindrical gear fixedly connected to a differential housing, wherein the pinion shaft is connected to a universal joint of the motor vehicle, the pinion of the pinion shaft meshes with the bevel gear teeth of the hollow shaft, and the cylindrical gear teeth of the hollow shaft mesh with the cylindrical gear teeth of the differential.

[0011] The pinion shaft connects to the vehicle's universal joint, which transmits the driving torque provided by the vehicle's internal combustion engine and / or electric motor. A hollow shaft is arranged transversely to the axis of the pinion shaft and the longitudinal axis of the vehicle. The cylindrical gear teeth of the hollow shaft transmit the driving torque to the differential. The hollow shaft forms the countershaft of the rear axle drivetrain and enables a non-centralized arrangement of the differential. The use of the countershaft provides greater structural space for integrating the power motor and eliminates the quasi-hyperboloid offset of the bevel gear teeth. The elimination of the quasi-hyperboloid offset reduces power loss due to the lack of shearing action from the bevel gear drive and allows for the use of only one type of lubricant for the entire rear axle drivetrain (H-HAG).

[0012] In one embodiment of the rear axle drivetrain, the differential is connected to the transmission of the drive motor.

[0013] In one embodiment of the rear axle drivetrain, a connecting shaft passes through a hollow shaft and has a cylindrical gear, which is part of the transmission mechanism. In another embodiment, the transmission mechanism is connected to a stacking unit, which is connected to the output shaft of the differential. In yet another embodiment, the stacking unit includes a double-row planetary gear mechanism having a free-running / rotatable, integral ring gear for two planetary gear sets. In yet another embodiment, the double-row planetary gear mechanism includes a first planet carrier and first planetary gears connected to the differential housing, a first sun gear connected to the transmission, a second planet carrier and second planetary gears connected to the output shaft, and a second sun gear fixed relative to the housing.

[0014] In one embodiment, the rear axle drivetrain includes a lubrication system that delivers lubricating oil to an oil reservoir based on gears and then distributes the oil to lubrication points due to gravity.

[0015] The subject matter of the present invention also relates to a powertrain for a plug-in hybrid electric vehicle (PHEV), the powertrain comprising an internal combustion engine and at least one electric motor and a rear axle drive mechanism according to the invention.

[0016] In one embodiment of the powertrain, the drive motor is connected to the differential via a transmission. In one embodiment, the drive motor is a permanently connected drive motor with a fixed gear ratio (1st gear). The advantages of a permanently connected drive motor include: minimizing dead time in torque-boosting and regenerative modes, eliminating traction interruptions due to gear shifting, and saving weight by eliminating the shifting mechanism.

[0017] In one embodiment of the powertrain, a drive module (eTV drive module) including a motor and power electronics is connected to the differential of the rear axle drivetrain via a connecting shaft, a transmission, and a stacking unit. Therefore, the eTV system includes the eTV drive module (motor and integrated power electronics) and a mechanical stacking unit.

[0018] In one implementation, the power motor and eTV drive module are cooled by an active water cooling system.

[0019] The subject matter of this invention also relates to a method for torque distribution (electric torque vectoring, eTV) between two output shafts of the rear axle of a motor vehicle, particularly a PHEV. In this method, a drive module (eTV drive module) causes acceleration or deceleration of the output shafts via a transmission (eTV transmission) and a stacking unit (eTV stacking unit). The stacking unit has a double-row planetary gear mechanism comprising a first planet carrier and first planetary gears connected to a differential housing, a first sun gear connected to the transmission, a second planet carrier and second planetary gears connected to one of the output shafts, and a second sun gear fixed relative to the housing, the output shafts being connected to the second planet carrier of the stacking unit. The drive module includes a motor and power electronics.

[0020] The advantages of electric torque vectoring systems are that they can achieve high torque differential in a compact structural space, achieve higher adjustment quality compared to hydraulic systems, enable intervention in rear wheel acceleration and deceleration (always in the opposite direction), and thus enable rapid and stable intervention in the vehicle's driving dynamics.

[0021] Other advantages and design solutions of the present invention are derived from the specification and drawings.

[0022] It goes without saying that the features described above and those to be elaborated below can be applied not only in the corresponding combinations described, but also in other combinations or individually, without departing from the scope of the present invention. Attached Figure Description

[0023] The present invention is schematically illustrated with reference to the accompanying drawings and further described with reference to the drawings. In the drawings: Figure 1 A schematic diagram of one embodiment of a hybrid rear axle drivetrain (H-HAG) with an electronic torque vector distribution system (eTV) according to the present invention is shown. Detailed Implementation

[0024] Figure 1 A schematic diagram of one embodiment of a hybrid rear axle drivetrain (H-HAG) with an electronic torque vector distribution system (eTV) according to the present invention is shown.

[0025] The pinion shaft 1 is the interface with the universal joint in the vehicle. The bevel / cylindrical gear shaft 2, providing through-drive to the eTV module 6, is a transversely hollow shaft with bevel gear teeth and cylindrical gear teeth, through which the drive shaft 2a from the eTV drive module 6 to the eTV transmission mechanism 7 passes. The differential 3 with cylindrical gears includes a differential housing with fixedly connected cylindrical gears, a connection to the eTV superposition unit 8, and a connection to the transmission 5 of the drive motor 4. Speed ​​balancing is achieved by implementing a bevel gear differential. The drive motor 4 is permanently connected to the transmission 5. The transmission 5 of the drive motor 4 includes a planetary gear mechanism and is permanently connected to the differential 3 housing. The planetary gear mechanism is configured such that the sun gear is connected to the drive shaft of the drive motor 4, the planetary gears and planet carriers establish a connection with the differential 3 housing, and the ring gear is fixed relative to the housing. The drive module 6 for electric torque vectoring includes a motor and integrated power electronics. A form-locking connection exists between the eTV transmission mechanism 7 and the gearbox 7 via a mating tooth / key connection. The eTV transmission mechanism 7 has different cylindrical gear stages. The eTV stack unit 8 includes a double-row planetary gear mechanism, which has an integral ring gear 8a for free movement of the two planetary gear sets, a right planet carrier 8b and a right planetary gear connected to the differential 3 housing, a right sun gear 8c connected to the eTV drive module 6 via the eTV transmission mechanism 7, a left planet carrier 8d and a left planetary gear connected to the left output shaft 9a, and a left sun gear 8e fixed relative to the housing. The left output shaft 9a and the right output shaft 9b form an interface with a universal joint in the vehicle.

[0026] In the electric torque vectoring system (eTV), the eTV drive module 6, in conjunction with the eTV superposition unit 8, causes a targeted redistribution of drive torque among the wheels based on the direction of rotation. Here, the increase or decrease in torque of each wheel is numerically equal to that of the others. The eTV drive module 6 drives the right sun gear 8c of the superposition unit 8 via the eTV transmission mechanism 7. The sun gear 8c drives the ring gear 8a and the left planetary gear set 8d via the right planetary gear set 8b. Thus, the left planetary carrier 8d and the connected left output shaft 9a are accelerated or decelerated according to the direction of rotation of the eTV drive module 6. The right output shaft 9b is accelerated or decelerated by the same value in the opposite direction via the bevel gear teeth of the differential 3.

[0027] List of reference numerals in the attached diagram: 1. Pinion shaft 2. Bevel gear / cylindrical gear shaft for eTV through-drive 2a Connecting shaft 3. Differential with cylindrical gears 4. Power motor 5. Power motor and transmission 6 eTV driver modules 7 eTV transmission mechanism 8 eTV overlay units 8a Gear Ring 8b Right Planetary Gear / Right Planet Carrier 8c Right Sun Gear 8T Left Planetary Gear / Left Planet Carrier 8e Left Sun Chakra 9 Output shaft 9a Left Output Shaft 9b Right output shaft.

Claims

1. A rear axle transmission mechanism for a motor vehicle, comprising a pinion shaft (1), a hollow shaft (2) having bevel gear teeth and cylindrical gear teeth, and a differential (3) having a cylindrical gear fixedly connected to a differential (3) housing, wherein, The pinion shaft (1) is connected to the universal joint of the motor vehicle. The pinion of the pinion shaft (1) meshes with the bevel gear teeth of the hollow shaft (2). The cylindrical gear teeth of the hollow shaft (2) mesh with the cylindrical gear teeth of the differential (3). The connecting shaft (2a) passes through the hollow shaft (2). The connecting shaft (2a) has a cylindrical gear. The cylindrical gear of the connecting shaft (2a) is a component of the transmission mechanism (7). The transmission mechanism (7) is connected to the stacking unit (8). The stacking unit is connected to the output shaft (9a, 9b) of the differential (3).

2. The rear axle transmission mechanism according to claim 1, characterized in that, The differential (3) is connected to the transmission (5) of the power motor (4).

3. The rear axle transmission mechanism according to claim 1, characterized in that, The stacking unit (8) includes a double-row planetary gear mechanism having a free-running, integral gear ring (8a) for two planetary gear sets.

4. The rear axle transmission mechanism according to claim 3, characterized in that, The double-row planetary gear mechanism includes: a first planet carrier (8b) and a first planetary gear connected to the differential (3) housing, a first sun gear (8c) connected to the transmission mechanism (7), a second planet carrier (8d) and a second planetary gear connected to the output shafts (9a, 9b), and a second sun gear (8e) fixed relative to the housing.

5. A powertrain for a plug-in hybrid electric vehicle (PHEV), the powertrain comprising an internal combustion engine and at least one electric motor and a rear axle drive mechanism according to any one of claims 1-4.

6. The power transmission system according to claim 5, characterized in that, The power motor (4) is connected to the differential (3) via the transmission (5).

7. The power transmission system according to claim 5 or 6, characterized in that, The drive module (6), which includes a motor and power electronics, is connected to the differential (3) via a connecting shaft (2a), a speed change mechanism (7), and a stacking unit (8).

8. A method for distributing torque between two output shafts (9a, 9b) of a motor vehicle rear axle, the rear axle having a rear axle drive mechanism according to any one of claims 1-4, wherein, The drive module (6) causes the output shafts (9a, 9b) to accelerate or decelerate through the transmission mechanism (7) and the stacking unit (8). The stacking unit has a double-row planetary gear mechanism, which includes a first planet carrier (8b) and a first planetary gear connected to the differential (3) housing, a first sun gear (8c) connected to the transmission mechanism (7), a second planet carrier (8d) and a second planetary gear connected to one of the output shafts (9a, 9b), and a second sun gear (8e) fixed relative to the housing. The output shaft is connected to the second planet carrier (8e) of the stacking unit (8).

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