Manual transmission for use with an electric motor

Abstract

Manual transmission (1) with two gears, wherein an input shaft (2) of the manual transmission (1) can be driven by means of an electric machine (3), wherein the input shaft (2) is connected to an output shaft (5) of the manual transmission (1) via at least one unidirectional clutch (4), wherein a planetary stage (6) arranged parallel to the clutch (4) is connected to the output shaft (5) of the manual transmission (1), for driving a wheel (30) or an axle (7) having wheels (30) of a motor vehicle, wherein the planetary stage (6) is switchable, characterized in that a sun gear (17) of the planetary stage (6) can be fixed in place for switching the gears.

Description

[0001] The invention relates to a manual transmission with two gears, wherein an input shaft of the transmission can be driven by means of an electric machine, wherein the input shaft is connected to an output shaft of the transmission via at least one unidirectional clutch.

[0002] Such a manual transmission is known in practice. It is used in conjunction with an electric motor whose rotor shaft houses two spur gears, one of which is permanently connected to the rotor shaft and the other of which can be connected to the rotor shaft in a rotationally fixed manner when a clutch is engaged. The spur gear, which is permanently connected to the rotor shaft, meshes with a spur gear that is mounted in another shaft via a freewheel. This shaft houses another spur gear in a rotationally fixed manner, which meshes with the spur gear of the rotor shaft, which can only be engaged via the clutch. The shaft to which the freewheel of the transmission is assigned houses another spur gear in a rotationally fixed manner, which interacts with a gear of a differential. This differential can drive two wheels arranged on the sides of a motor vehicle, which are assigned to two axle sections of an axle of the motor vehicle.

[0003] The disadvantage of this design of the gearbox is that the spur gears mounted in the rotor shaft are constantly in engagement with the spur gears of the shaft arranged parallel to the rotor shaft.

[0004] The freewheel used in the gearbox is a one-way clutch. If the other clutch is closed so that the spur gear assigned to this clutch is connected in a rotationally fixed manner to the rotor shaft, the shaft arranged parallel to the rotor shaft is driven at such an angular velocity that the freewheel is overtaken and consequently the torque is transmitted, bypassing the freewheel.

[0005] DE 36 19 368 A1 discloses a manual transmission according to the preamble of claim 1.

[0006] Further prior art is known from JP 2011- 169 375 A and DE 10 2005 045 281 A1.

[0007] The object of the invention is to develop a manual transmission in such a way that easy switching of the gears of the transmission is possible with a simple design.

[0008] In the manual transmission according to the invention, a planetary stage arranged parallel to the clutch is connected to the output shaft of the transmission for driving a wheel or an axle having wheels of a motor vehicle, wherein the planetary stage is switchable.

[0009] Furthermore, in the manual transmission according to the invention, a sun gear of the planetary stage can be fixed for shifting the gears.

[0010] The sun gear can preferably be secured by means of an actuator, in particular a brake. The brake is designed in particular as a dry brake.

[0011] Due to the design of the manual transmission, in one gear, especially first gear, power flows only through the single-acting clutch, as the planetary gears or planetary gear set rotate in a single unit. Shifting the planetary gear, i.e., setting the planetary gear, shifts to the other gear, especially second gear, which then overrides the single-acting clutch.

[0012] In particular, the manual transmission is designed such that the input shaft is an intermediate shaft, wherein a rotor shaft of the electric machine is connected to the intermediate shaft by means of a spur gear stage or a planetary stage.

[0013] The single-acting clutch can be designed in different ways. It is usually a friction-locking or positive-locking clutch. For example, the clutch is designed as a freewheel or a switchable clutch. This switchable clutch is, for example, a claw clutch.

[0014] The clutch, which is designed as a switchable clutch, can be configured such that the clutch operates in one direction of rotation in one switching position and in the opposite direction of rotation in another switching position. This configuration enables recuperation in one gear, particularly in first gear, and thus allows the electric motor to operate in generator mode. In contrast to a clutch that only acts on one side, which only allows torque to be transmitted during motor operation of the electric motor, a claw clutch modified in the opposite direction can then transmit torque to the electric motor in the opposite direction of rotation. However, this requires a switchable clutch design.

[0015] The planetary stage is preferably designed such that the input shaft can be brought into operative connection via the clutch with a ring gear or a ring gear carrier of the planetary stage arranged parallel to the clutch, wherein the ring gear or ring gear carrier is connected to the output shaft of the transmission. The ring gear carrier, in particular, has external teeth that interact with a gearwheel, which is non-rotatably connected to the output shaft and is designed, in particular, as a spur gear.

[0016] The manual transmission, for example, is used to drive the wheels located on both sides of the vehicle. The output shaft interacts with a differential between two axle sections of the vehicle's axle.

[0017] Alternatively, the manual transmission is designed to drive a single wheel, with two wheels on the same axle of the motor vehicle being drivable independently of one another by means of mirror-symmetrically arranged manual transmissions. The planetary gear stages, in particular the sun gears of the different powershift transmissions, can be fixed together. This creates an individual wheel drive, with two electric motors acting on a respective wheel via a respective unidirectional clutch / planetary gear arrangement. A particular advantage here is that only a single actuator is required to fix the two planetary gear stages or the sun gears of the two planetary gear stages. This means that only a single actuator is required to change gears, and simultaneous switching of both drives is also ensured.

[0018] The invention, including the described developments, thus proposes a manual transmission with two gears for an electrically driven wheel or axle. For this purpose, an electric machine with a spur gear or planetary stage is connected to an intermediate shaft, which in turn is connected to a differential via at least one unidirectional clutch, designed for example as a freewheel, and a planetary stage arranged parallel to it, which is designed in particular with a fixable sun gear, for driving the axle or to a gearwheel of a shaft of an axle section for driving a single wheel. This results in a power flow over only two gear stages in one gear, in particular in first gear, where the planetary stage or the sun gear of the planetary stage is not fixed or braked, since the planetary set rotates in a block. By fixing the planetary set orof the sun gear, the shift to the other, in particular second, gear takes place, whereby the one-sided clutch is deactivated, in particular the freewheel is then overtaken.

[0019] The manual transmission according to the invention, taking into account the described developments, is powershiftable by means of a brake / clutch that interact with the planetary gear stage, and the single-sided clutch, in particular the freewheel. Powershift capability can be achieved with just one actuator. The fact that the brake / clutch can be designed as a dry brake results in low drag losses and thus high efficiency. In first gear (primary gear), with only two gear stages in the power flow and in motion, the fact that the switchable planetary gear set rotates in the block and is not located in the power flow results in significant efficiency advantages and no load on the planetary gear set components. Very good fail-safe behavior is observed. Thus, freewheeling occurs in first gear, and a normally open brake or clutch for second gear.When using a freewheel in first gear, recuperation is only possible in second gear. If recuperation capability is required in first gear, the freewheel is supplemented with a clutch, preferably a dog clutch. Preferably, only one actuator is provided for the dog clutch and the brake. This transmission design allows for splash lubrication, thus eliminating the need for an oil pump. Due to the transmission design, it requires only a minimal number of radial shaft seals. This results in high efficiency.

[0020] Further features of the invention emerge from the subclaims, the attached drawings and the description of the preferred embodiments shown in the drawings, without being limited thereto.

[0021] It shows: Fig. 1 a first embodiment of the manual transmission, with connection to an electric motor and a differential gear, in a schematic representation, Fig. 2 a preferred bearing and sealing concept for the manual transmission according to the first embodiment, Fig. 3 a second embodiment of the manual transmission, with a mirrored arrangement of two manual transmissions in interaction of the respective manual transmission with an electric machine and a single wheel of an axle of a motor vehicle, illustrated in a schematic representation.

[0022] The embodiment according to Fig. 1 shows a manual transmission 1 with two gears. An input shaft 2 of the transmission 1 is driven by an electric motor 3. The input shaft 2 is connected to an output shaft 5 of the transmission 1 via a one-way clutch 4. A planetary stage 6 or planetary gear set arranged parallel to the clutch 4 is connected to the output shaft 5 via a spur gear stage 23, 24 for driving an axle of a motor vehicle, which is in particular a passenger car and has two wheels (not shown). This axle 7 has two shafts 8 and 9, one shaft being connected to one wheel and the other shaft to the other wheel. A differential gear 10, the input of which is formed by the output shaft 5, operates between the two shafts 8 and 9.

[0023] Specifically, the input shaft 2 is an intermediate shaft. A rotor shaft 11 of the electric motor 3 is non-rotatably connected to a spur gear 12, which meshes with a spur gear 13 non-rotatably connected to the input shaft 2 of the transmission 1. The rotor of the electric motor 3 is designated by reference numeral 14. Instead of the spur gear stage formed by the spur gears 12 and 13, a planetary gear stage may well be provided.

[0024] The clutch 4 is designed as a freewheel, for example, using clamping rollers. Optionally, a combination with a claw clutch and corresponding actuators can be provided, particularly if operation in generator mode, thus in recuperation mode, is desired instead of operating the electric motor 3 in motor mode.

[0025] Regarding the design of planetary stage 6, a planet carrier 15, which houses planetary gears 16, is non-rotatably connected to the input shaft of transmission 1. The planetary gears 16 mesh with a sun gear 17, which is non-rotatably connected to a shaft 18. The shaft 18, and thus the sun gear 17, can be secured by means of an actuator 19 designed as a brake. This actuator can be switched and clamps a brake disc or brake discs 20 that are non-rotatably connected to the shaft 18, comparable to brakes in automatic transmissions. The brake is, in particular, a dry brake.

[0026] The planetary gears 16 further mesh with a ring gear 21 of the planetary stage 6, which interacts with a ring gear carrier 22, which interacts with the overrunning clutch 4. The ring gear carrier 22 is connected radially outwardly to a spur gear 23, which meshes with a spur gear 24, which is rotationally fixedly connected to the output shaft 5. The output shaft 5 and a differential housing 25 form a single structural unit.

[0027] The operation of the manual transmission 1 described above, which can be shifted under load, is as follows: In first gear (primary gear), with the actuator 19 in a functional position in which the sun gear 17 is not fixed, only two gear stages are in the power flow and in motion. Specifically, in first gear, the rotor shaft 11 is driven via the rotor 14, and from this, via the spur gear 12, the spur gear 13. The spur gear 13 drives the input shaft 2, and via the one-way clutch 4, the ring gear carrier 22 and consequently the spur gear 23. The spur gear 23 drives the spur gear 24, and this, via the differential gear 10, drives the two shafts 8 and 9 assigned to the wheels of the motor vehicle. Due to the non-fixed sun gear 17, the switchable planetary stage 6 rotates in a block and is not in the power flow.

[0028] If the actuator 19 is controlled in such a way that the sun gear 17 is fixed via the fixed brake disc 20, the manual transmission 2 is in second gear (secondary gear). With the sun gear 10 stationary, the torque flow occurs from the rotor 14 via the rotor shaft 11 to the spur gear 12, from there to the spur gear 13 into the input shaft 2, which has an angular velocity such that the freewheel is overrun. The planet carrier 15 rotates at the same angular velocity as the input shaft 2, and the planet gears 16 driven by it drive the ring gear 21. Consequently, the ring gear carrier 22 rotates at the same angular velocity as the ring gear 21. The ring gear carrier 22 drives the spur gear 23, which is rigidly connected to it, via its external toothing. This, in turn, drives shafts 8 and 9 via the spur gear 24 and the differential gear 10.

[0029] When using a freewheel clutch 4, due to the design of the transmission according to the exemplary embodiment, recuperation is only possible in second gear. If recuperation capability is required in first gear, the freewheel is supplemented by a clutch, preferably a dog clutch. Preferably, only one actuator is provided for the dog clutch and the brake.

[0030] Fig. Figure 2 illustrates the bearing and sealing concept. Reference numeral 26 designates the first bearings used in this arrangement, which are designed as axial bearings, in particular axial needle bearings. Reference numeral 27 designates second bearings used in this arrangement, which are designed as radial bearings, in particular as radial (needle) bearings. Reference numeral 28 designates third bearings used in this arrangement, which are deep groove ball bearings, angular contact ball bearings, tapered roller bearings, or cylindrical roller bearings. With regard to the sealing concept, reference numeral 29 designates four radial shaft seals used in this arrangement. Also illustrated is the actuator 18 designed as a brake actuator, which can be configured in different variants, for example, electromotive, electromagnetic, hydraulic, or pneumatic.

[0031] The embodiment according to the Fig. 3 differs from that according to the Fig. 1 in that instead of a manual transmission, two mirror-inverted manual transmissions 1, 1 are provided. In contrast to the embodiment according to the Fig. 1, a common actuator 19 is provided for the brake discs 20 assigned to the two transmissions 1, 1, so that the two sun gears 17 of the two transmissions 1, 1 can be simultaneously locked or released. On the output side, the spur gear 24 does not interact with the output shaft 5 assigned to the differential gear 10, but rather this output shaft 5 is firmly connected to the respective shaft 8 or 9. In the embodiment according to the Fig. 3 is an independent wheel drive of the wheels 30 of axle 7 of the motor vehicle. The respective shaft 8 or 9 interacts with the associated wheel 30 via a cardan shaft 31.

[0032] Regarding the operation of this arrangement formed by the two gearboxes 1, 1, reference is made to the explanations on the operation of the embodiment of the Fig. 1. The bearing concept of the embodiment according to Fig. 3 corresponds to that of the embodiment according to Fig. 1. Regarding the sealing concept, the embodiment according to the Fig. 3 six radial shaft seals are provided.

[0033] In particular, the order may be made in accordance with Fig. 1 is to be understood as a basic solution or drive, which in duplicate then represents the arrangement according to Fig. 3, in the sense of a construction kit. List of reference symbols 1 manual transmission 2 input shaft 3 Electric machine 4 Clutch 5 Output shaft 6 planetary stage 7 Axis 8 Wave 9 Wave 10 differential gears 11 Rotor shaft 12 Spur gear 13 Spur gear 14 Rotor 15 planet carriers 16 Planetary gear 17 Sun gear 18 Wave 19 Actuator 20 brake disc 21 ring gear 22 ring gear carrier 23 Spur gear 24 spur gear 25 differential housing 26 warehouses 27 camps 28 warehouses 29 Radial shaft seal 30 wheels 31 Cardan shaft

Claims

[1] Manual transmission (1) with two gears, wherein an input shaft (2) of the manual transmission (1) is drivable by means of an electric machine (3), wherein the input shaft (2) is connected to an output shaft (5) of the manual transmission (1) via at least one unidirectional clutch (4), wherein a planetary stage (6) arranged parallel to the clutch (4) is connected to the output shaft (5) of the manual transmission (1), for driving a wheel (30) or an axle (7) having wheels (30) of a motor vehicle, wherein the planetary stage (6) is switchable, characterized by that a sun gear (17) of the planetary stage (6) can be fixed for shifting the gears. [2] Manual transmission (1) according to claim 1, characterized by that the input shaft (2) is an intermediate shaft, wherein a rotor shaft (11) of the electric machine (3) is connected to the input shaft (2) by means of a spur gear (12) or a planetary stage. [3] Manual transmission (1) according to claim 1 or 2, characterized bythat the single-acting clutch (4) is a frictional or positive-locking clutch. [4] Manual transmission (1) according to claim 3, characterized by that the clutch (4) is designed as a freewheel. [5] Manual transmission (1) according to claim 3, characterized by that the clutch (4) is designed as a switchable clutch. [6] Manual transmission (1) according to claim 5, characterized by that the switchable clutch (4) is designed as a claw clutch. [7] Manual transmission (1) according to one of claims 1 to 6, characterized by that the clutch (4) is designed as a switchable clutch, wherein the clutch (4) is effective in one switching position in one direction of rotation and in another switching position in the opposite direction of rotation. [8] Manual transmission (1) according to one of claims 1 to 7, characterized bythat the input shaft (2) can be brought into operative connection with a ring gear carrier (22) of the planetary stage (6) arranged parallel to the clutch (4) via the clutch (4), the ring gear carrier (22) being connected to the output shaft (5) of the manual transmission (1). [9] Manual transmission (1) according to claim 8, characterized by that the ring gear carrier (22) has an external toothing (23) which cooperates with a gear (24) which is connected in a rotationally fixed manner to the output shaft (5) and which is designed in particular as a spur gear. [10] Manual transmission (1) according to one of claims 1 to 9, characterized by that the sun gear (17) can be fixed by means of an actuator (19), in particular a brake. [11] Manual transmission (1) according to claim 10, characterized by that the brake is designed as a dry brake. [12] Manual transmission (1) according to one of claims 1 to 11, characterized bythat the transmission (1) serves to drive wheels (30) of the motor vehicle arranged on both sides of the motor vehicle, wherein the output shaft (5) interacts with a differential gear (10) of two axle sections of the axle (7) of the motor vehicle. [13] Manual transmission (1) according to one of claims 1 to 11, characterized by that the manual transmission (1) serves to drive a single wheel (30), wherein two wheels (30, 30) of the same axle (7) of the motor vehicle can be driven independently of one another by means of mirror-symmetrically arranged powershift transmissions (1, 1), wherein the planetary stages (6, 6), in particular the sun gears (17, 17) of the manual transmissions (1, 1) can be fixed jointly. [14] Manual transmission (1) according to claim 13, characterized by that a single actuator (19) can be brought into operative connection with the planetary stages (6, 6), in particular the sun gears (17, 17) of the manual transmission (1, 1). [15] Manual transmission (1) according to claim 14, characterized bythat the clutches (4) designed as switchable clutches can also be switched by means of the single actuator (19).

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