Electric drive for a vehicle and vehicle

Abstract

An electric drive for a vehicle is proposed. The electric drive comprises an electric motor, a maximum of one negative gear set, and a switching element. The negative gear set comprises a sun gear, a planetary gear mounted on a carrier, and a ring gear. The switching element is designed to switch between a first switching stage and a second switching stage of the electric drive. An input of the negative gear set is designed to rotate in different directions of rotation in the first switching stage and the second switching stage, and an output of the negative gear set is designed to rotate in the same direction of rotation in the first switching stage and the second switching stage. In the first switching stage, the carrier is connected to a housing in a rotationally fixed manner, and in the second switching stage, the carrier is connected to the sun gear.

Description

[0001] The present invention relates to an electric drive for a vehicle and a vehicle.

[0002] A gear step in a transmission refers to the difference in the gear ratio between successive gears. In a vehicle transmission, there are different gears that allow the driver to vary the speed of the electric motor in relation to the vehicle's speed. Each gear has a specific gear ratio that imparts different torques and speeds to the drive wheels. Due to design reasons, there is a lower limit for a gear step for driving a vehicle in the same direction, which is determined by the design characteristics of the transmission, in particular the positive gear set. This means that when driving the vehicle in the same direction, e.g., forward, a gear step cannot be freely selected or a free selection of the gear step involves considerable design effort. There is therefore a need to provide an improved electric drive.

[0003] The object of the invention is achieved by an electric drive and a vehicle according to the independent claims.

[0004] According to a first aspect, an electric drive for a vehicle is proposed. The electric drive comprises an electric motor, a maximum of one negative gear set, and a switching element. The negative gear set comprises a sun gear, a planetary gear mounted on a carrier, and a ring gear. The switching element is designed to switch between a first switching stage and a second switching stage of the electric drive. An input of the negative gear set is designed to rotate in different directions of rotation in the first switching stage and in the second switching stage, and an output of the negative gear set is designed to rotate in the same direction of rotation in the first switching stage and in the second switching stage. In the first switching stage, the carrier is connected to a housing in a rotationally fixed manner, and in the second switching stage, the carrier is connected to the sun gear.By designing the input of the negative gear set so that it can rotate in different directions for different gear stages and designing the output of the negative gear set so that it can rotate in the same direction for different gear stages, two gears with the same output directions of rotation can be realized with different input directions of rotation. Due to the fact that the electric drive comprises a maximum of one negative gear set, different gears in conjunction with different directions of rotation of the electric motor can be realized with a simplified structural design with the same direction of rotation of the output of the negative gear set. For example, an output shaft of the electric drive can rotate in the same direction of rotation for different gear stages while at the same time the electric motor has different directions of rotation. This means:The maximum of one negative gear set can convert different directions of rotation provided by the electric motor, so that the direction of rotation at the output of the negative gear set is identical for each direction of rotation of the electric motor. A complex structural design comprising a plurality of negative gear sets can thus be avoided. The electric drive can therefore allow the electric motor to operate in both generator and motor mode. In particular, generator and motor mode can be achieved through non-positive connections in the switching stages. This means that a non-rotatable connection can, in particular, be non-positive.

[0005] In one embodiment, the electric drive can further comprise an axially parallel transmission. The negative gear set can be arranged on a first shaft (e.g., a rotor shaft), a second shaft (e.g., an intermediate shaft), or a third shaft (e.g., an output shaft) of the transmission. This allows the positioning of the negative gear set to be adapted depending on the design, for example, the available installation space.

[0006] In one embodiment, the first gear stage can be generated via a block shift, and the second gear stage via a gear set shift with different rotation directions. This means that a first gear of the electric drive can be generated via a block shift, and a second gear of the electric drive can be generated via a gear set shift with a changed rotation direction of the input of the negative gear set. This can simplify the design of the electric drive.

[0007] In one embodiment, the first gear stage and the second gear stage can have a maximum step increment of 2.6. This means that with the electric drive, a step increment from a first gear to a second gear of less than 2.6 can be achieved. This means that a minimum step increment can be determined solely by the structural limitations of the sun gear compared to the ring gear. With a maximum of one negative gear set, in combination with different rotational directions of an electric motor, a positive step increment smaller than for positive gear sets can be achieved, for example, in a step increment window of 1.3-2.6. This makes it possible to circumvent the limitations of conventional planetary gear sets with regard to a step increment.

[0008] In one embodiment, the shifting element can be an active shifting element. Furthermore, the electric drive can comprise an actuator. The actuator can be configured to actuate the shifting element. The actuator can be a shift drum. Using a shift drum can enable faster and more precise gearshift control. Furthermore, several different actuators can be operated in one rotational movement.

[0009] In one embodiment, the electric drive can further include a parking lock. The shift drum can be configured to actuate the parking lock. This can simplify the integration of a parking lock. In particular, the use of the shift drum to actuate the shifting element and the parking lock can simplify the design.

[0010] In one embodiment, the switching element can be an active switching element. The electric drive can further comprise an actuator. The actuator can be designed to actuate the switching element. The switching element can be a claw, a friction clutch, or a brake. This allows the switching element to be actuated in a suitable manner.

[0011] In one embodiment, the negative gear set can be configured to provide a third gear stage. The third gear stage is a neutral gear. In neutral gear, the web is free.

[0012] According to a second aspect of the invention, a vehicle is proposed. The vehicle comprises an electric drive as described above.

[0013] The present invention will be described below by way of example only, with reference to the accompanying figures. They show: Fig. 1a-1d show various embodiments of an electric drive 100, 100b, 100c, 100d with different arrangements on a shaft of a transmission; and Fig. 2 shows an embodiment of a vehicle.

[0014] Fig. 1a-1d show various embodiments of an electric drive 100, 100b, 100c, 100d with different arrangements on a shaft of a transmission. Fig. 1a shows an arrangement of an electric drive 100 on a rotor shaft of a transmission.

[0015] The electric drive 100 for a vehicle comprises an electric motor 110, a maximum of one negative gear set 120, and a shifting element 130. The negative gear set 110 comprises a sun gear 122, a planetary gear 124 mounted on a carrier 140, and a ring gear 126. The shifting element 130 is designed to switch between a first shifting stage and a second shifting stage of the electric drive 100. An input of the negative gear set 120 is designed to rotate in different directions of rotation in the first shifting stage and in the second shifting stage, and an output of the negative gear set 120 is designed to rotate in the same direction of rotation in the first shifting stage and in the second shifting stage. In the first shifting stage, the carrier 140 is connected to a housing in a rotationally fixed manner, and in the second shifting stage, the carrier 140 is connected to the sun gear 122 in a rotationally fixed manner.By using a negative gear set 120, a gear ratio of i0=-2, for example, can be enabled for a first gear stage and a gear ratio of i2=1, for example, can be enabled for a second gear stage. Because different directions of rotation at the input of the negative gear set 120 lead to the same direction of rotation at an output of the negative gear set 120 for the two different gear stages or gears, the gear ratio of the first gear stage can be changed to a gear ratio of 2. This means that the first gear stage can have a gear ratio of i1=2. This makes it possible to make a gear step of, for example, 2 between a first gear and a second gear. The gear step of, for example, 2 can be made possible with a maximum of one negative gear set 120. This makes it possible to reduce the design effort of the electric drive 100.

[0016] The inventors have discovered that an improved electric drive 100 can be provided by using a maximum of one negative gear set 120 in conjunction with an electric motor 110. In particular, the improved electric drive 100 can provide a gear step that is smaller than a technically feasible gear step for positive gear sets. A smaller gear step can be made possible by combining an electric motor that operates with different directions of rotation for the different gears. This means that the electric motor 110 outputs different directions of rotation for the two different gear stages of the electric drive 100. Accordingly, the electric motor 110 is briefly stopped to shift between gears in order to reverse a direction of rotation of the electric motor 110.

[0017] The different directions of rotation of the electric motor 110 are transmitted to an input of the negative gear set 120. Due to the structural design of the negative gear set 120, i.e. the rotationally fixed connection of the web 140 to a housing in the first switching stage and the rotationally fixed connection of the web 140 to the sun gear 122 in the second switching stage, the negative gear set 120 can output the same direction of rotation at an output for both switching stages. In the first switching stage, the web 140 can therefore be held fixed. This allows a negative gear ratio to be achieved. This means that the sun gear 122 and the ring gear 126 can rotate in opposite directions. In the second switching stage, the sun gear 122 can be driven and the ring gear 126 can be held fixed. This allows a positive gear ratio to be achieved. This means that the web 140 can rotate with the sun gear 122 in the second switching stage.By providing a negative gear ratio for the first gear stage and a positive gear ratio for the second gear stage for different rotational directions of the electric motor 110, the different rotational directions can be compensated, so that only one rotational direction is output at the output of the electric drive 100 for both gear stages. This enables operation of a vehicle in one direction of travel, for example, in the forward direction, with a gear step of, for example, 2.

[0018] The combination of the electric motor 110, which is designed to output different directions of rotation, with the maximum of one negative gear set 120 can therefore enable a simple structural design of an electric drive 100 with a step in the range of 2.

[0019] The present electric drive 100 can be used to implement special applications such as pickups with crawler driving functions. For example, a customer specification can be a certain step increment (e.g., a step increment (i1 / i2) = 2). The inventors have determined that such a step increment can be achieved with a maximum of one negative gear set 120 as described above. However, this results in a reversal of the direction of rotation caused by the negative gear set 120. This reversal of the direction of rotation can be compensated for by a change in the direction of rotation or different directions of rotation of the electric motor 110. The electric motor 110 can therefore neutralize the reversal of the direction of rotation caused by the negative gear set 120. As a result, the electric drive 100 can provide a desired step in the range of two through the interaction of the electric motor 110 with the negative gear set 120 during operation in different directions of rotation.In particular, the electric drive 100 can enable a simple structural design, uniform wear of the tooth flanks due to the reversal of the direction of rotation and / or a reduction in installation space.

[0020] In general, the electric motor 110 can drive the sun gear 122, which is mounted in the planetary gear set with the planet 124, which is mounted in the carrier 140 and meshes with the ring gear 126. This means that to shift between the first gear stage and the second gear stage, the direction of rotation of the electric motor 100 is reversed. By reversing the direction of rotation of the electric motor 110, the "negative" gear ratio of the negative gear set 120 in first gear can result in a step change in the range of 2 compared to the gear ratio in second gear. Accordingly, the electric motor 100 according to the invention can provide a step change in the range of 2 for two gears (with the same direction of travel).

[0021] Furthermore, the electric drive 100 can include other optional components. For example, the electric drive 100 can include an output pinion 150, a shift drum 160 comprising an actuator 170, and / or a parking lock 180. The ring gear 126 can be rotationally fixedly connected to the pinion 150, for example, an output pinion 150. Optionally, the pinion 150 can be rotationally fixedly connected to a parking lock 180. The web 140 can be shifted into the first shift stage or a first gear and into the second shift stage or a second gear via the shifting element 130, for example, a claw. In first gear, the web 140 is rotationally fixedly connected to a housing. In second gear, the web 140 is rotationally fixedly connected to the sun gear 122.

[0022] Furthermore, the shifting element 130 can be configured to block the planetary gear 124. By blocking the planetary gear 124, the electric drive 100 can be operated in both motor and generator mode. In particular, there can be no freewheel for the first gear stage and the second gear stage.

[0023] In one embodiment, the electric drive 100 may further comprise an axially parallel transmission. The negative gear set 120 may be mounted on a first shaft, for example, a rotor shaft as shown in Fig. 1a, or a second shaft, for example an intermediate shaft as in Fig. 1b and Fig. 1c, or a third shaft, for example an output shaft as in Fig. 1d, of the transmission. The choice of arrangement of the negative gear set can determine the function and / or performance of a transmission. For example, it can be arranged on the output shaft to control the gear ratio and / or the torque transmitted to the vehicle wheels. Due to the structurally simple design of the electric drive 100, an arrangement on different shafts of the transmission can be simplified.

[0024] Optionally, the electric drive 100 may include an electronically controlled differential lock 190.

[0025] The electric drive 100b, 100c, 100d of the Fig. 1b-1d comprises in principle the same components as the electric drive 100. In contrast to the above-described electric drive 100 from Fig. 1a, the electric drive is not mounted on a rotor shaft as in Fig. 1a, but on an intermediate shaft Fig. 1b and Fig. 1c or an output shaft as in Fig. 1d. The above and below description of the electric drive 100 also applies to the electric drives 100b, 100c, 100d. This means that the electric drive 100b-d comprises an electric motor 110b-d, a maximum of one negative gear set 120b-d, and one shift element 130b-d. The one negative gear set 120b-d comprises a sun 122b-d, a planet 124b-d, and a ring gear 126b-d. Furthermore, the electric drive 100b-d comprises a carrier 140b-d and can comprise further optional components such as a pinion 150b-d, a shift drum 160b-d comprising an actuator 170b-d, a parking lock 180b-d, and / or an electronically controlled differential lock 190b-d.

[0026] In one embodiment, the first switching stage can be generated via a block switching system, and the second switching stage via a gear set switching system with different directions of rotation. By combining a block switching system with a gear set switching system, a reversal of the direction of rotation with a step change in the range of 2 can be achieved in a simplified manner.

[0027] In one exemplary embodiment, the first gear stage and the second gear stage can have a maximum step increment of 2.6. As described above, a step increment in the range of 2 can be achieved with the electric drive 100 according to the invention. In particular, a step increment of a maximum of 2.6, or a maximum of 2.4, or a maximum of 2.2, or a maximum of 2.0, or a maximum of 1.8 can be achieved. A minimum step increment can be determined by structural requirements for the sun gear 122 and the ring gear 126. Since the sun gear 122 and the ring gear 126 must have a difference in their diameters in order to operate a planetary gear, a step increment less than or equal to 1 cannot be achieved. However, the electric drive 100 according to the invention enables a minimum step increment that is structurally possible. For example, the step increment can be at least 1.2, or at least 1.3, or at least 1.5, or at least 1.7. That is to sayThe electric drive 100 can allow a step increment to be set in the range of 1.2-2.6. For example, a step increment of 2.0 can be set.

[0028] In one embodiment, the switching element 130 can be an active switching element. Furthermore, the electric drive can include an actuator 160. The actuator 160 can be configured to actuate the switching element 130. The actuator 160 can be a shift drum 160. The shift drum 160 can include an actuator 170 configured to control the shift drum. This means that the switching element 130 can be controlled by the actuator 170 via the shift drum 160.

[0029] In one embodiment, the electric drive 100 may further include a parking lock 180. The shift drum 160 may be configured to actuate the parking lock 180. This may simplify the integration of a parking lock 180.

[0030] In an alternative embodiment, the switching element 130 can be a claw, a clutch, or a brake. This allows the switching element 130 to be actuated in a suitable manner. In particular, a frictionally engaged switching element 130 can also be provided.

[0031] In one embodiment, the electric drive 100 may further include an output pinion 150. The ring gear 126 may be connected in a rotationally fixed manner to the output pinion 150. This allows for improved dissipation of torque generated at the ring gear 126.

[0032] In one embodiment, the negative gear set 120 can be configured to provide a third gear stage. The third gear stage is a neutral gear. In neutral gear, the web 130 is free. This means that components of the negative gear set 120 are not rotationally connected to the housing or to each other for the third gear stage.

[0033] Fig. 2 shows an embodiment of a vehicle 200. The vehicle comprises an electric drive 210, which is designed to drive the vehicle 200. The electric drive 210 comprises an electric motor 230 and a maximum of one negative gear set 220. For example, the electric drive is an electric drive as described with reference to Fig. 1 described. Reference symbol 100, 100b, 100c, 100d electric drive 110 electric motor 120, 120b, 120c, 120d negative gear set 122, 122b, 122c, 122d Sun 124, 124b, 124c, 124d Planet 126, 126b, 126c, 126d ring gear 130, 130b, 130c, 130d switching element 140, 140b, 140c, 140d bridge 150, 150b, 150c, 150d sprocket 160, 160b, 160c, 160d shift drum 170, 170b, 170c, 170d Actuator 180, 180b, 180c, 180d parking lock 190, 190b, 190c, 190d electronically controlled differential lock 200 vehicles 210 electric drive 220 electric motor 230 minus gear set

Claims

[1] An electric drive (100, 100b, 100c, 100d) for a vehicle, comprising: an electric motor (110, 110b, 110c, 110d); a maximum of one minus gear set (120, 120b, 120c, 120d), comprising: a sun (122, 122b, 122c, 122d); a planet (124, 124b, 124c, 124d) mounted on a web (130, 130b, 130c, 130d); and a ring gear (126, 126b, 126c, 126d); and a switching element (140, 140b, 140c, 140d), wherein the switching element (140, 140b, 140c, 140d) is designed to switch between a first switching stage and a second switching stage of the electric drive (100, 100b, 100c, 100d) and wherein an input of the negative gear set (120, 120b, 120c, 120d) is designed to rotate in different directions of rotation in the first switching stage and in the second switching stage, and an output of the negative gear set (120, 120b, 120c, 120d) is designed to rotate in the same direction of rotation in the first switching stage and in the second switching stage, wherein in the first switching stage the web (130, 130b, 130c, 130d) is connected in a rotationally fixed manner to a housing and in the second switching stage the web (130, 130b, 130c, 130d) is connected in a rotationally fixed manner to the sun (122, 122b, 122c, 122d). [2] The electric drive (100, 100b, 100c, 100d) according to claim 1, further comprising an axially parallel transmission and wherein the negative gear set (120, 120b, 120c, 120d) is arranged on a first shaft or a second shaft or a third shaft of the transmission. [3] The electric drive (100, 100b, 100c, 100d) according to one of the preceding claims, wherein the first switching stage is generated via a block circuit and the second switching stage is generated via a gear set circuit with different directions of rotation. [4] The electric drive (100, 100b, 100c, 100d) according to one of the preceding claims, wherein the first switching stage and the second switching stage have a step jump of a maximum of 2.

6. [5] The electric drive (100, 100b, 100c, 100d) according to one of the preceding claims, wherein the switching element (140, 140b, 140c, 140d) is an active switching element (140, 140b, 140c, 140d) and further comprising an actuator (160), wherein the actuator (160) is designed to actuate the switching element (140, 140b, 140c, 140d) and wherein the actuator (160) is a switching drum. [6] The electric drive (100, 100b, 100c, 100d) according to claim 5, further comprising a parking lock (180), where the shift drum is further designed to actuate the parking lock (180). [7] The electric drive (100, 100b, 100c, 100d) according to one of the preceding claims, wherein the switching element (140, 140b, 140c, 140d) is an active switching element (140, 140b, 140c, 140d) and further comprising an actuator, wherein the actuator is designed to actuate the switching element (140, 140b, 140c, 140d) and wherein the switching element (130) is a claw, a clutch or a brake. [8] The electric drive (100, 100b, 100c, 100d) according to any one of the preceding claims, further comprising an output pinion (150), wherein the ring gear (126, 126b, 126c, 126d) is connected in a rotationally fixed manner to the output pinion (150). [9] The electric drive (100, 100b, 100c, 100d) according to one of the preceding claims, wherein the negative gear set (120, 120b, 120c, 120d) is designed to provide a third gear stage, wherein the third gear stage is a neutral gear and wherein in the neutral gear the web (130, 130b, 130c, 130d) is free. [10] A vehicle (200) comprising: an electric drive (210) according to one of the preceding claims.

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