Patent ID: 12194825

Similar reference numerals may have been used in different figures to denote similar components.

DETAILED DESCRIPTION

FIG.1shows schematically a transmission layout according to a first embodiment of the present disclosure. The dual-motor electrical transmission for an electrical vehicle according to the first embodiment comprises a first electrical motor1, which is controlled by a first inverter controller1a, and a second electrical motor2, which is controlled by a second inverter controller2a. The first and second motors1,2are configured to drive the electrical vehicle. The transmission further comprises a first gear arrangement10, a second gear arrangement20and a summation box30.

The first gear arrangement10comprises a first gear arrangement first shaft10a, a first gear11and a second gear12, wherein each of the first and the second gears11,12can be selectively engaged and disengaged with the first gear arrangement first shaft10avia a first or second dog clutch11a,12a. The first gear arrangement10further comprises a first gear arrangement second shaft13and a first gear arrangement fixed gear set with gears14,15. Gear14is permanently engaged with the first gear arrangement second shaft, gear15is permanently engaged with the first gear arrangement first shaft10aand gears14,15are meshed with one another such that the first gear arrangement first shaft10ais coupled to the first gear arrangement second shaft13via the first gear arrangement fixed gear set14,15.

The second gear arrangement20comprises a second gear arrangement first shaft20aand a second gear arrangement first gear22, wherein the second gear arrangement first gear22can be engaged and disengaged with the second gear arrangement first shaft20avia a second gear arrangement first dog clutch22a. The second gear arrangement20further comprises a second gear arrangement second shaft23and two further gears24,25which are fixedly engaged with the second gear arrangement second shaft23, wherein one of the two further gears24,25is meshed with the second gear arrangement first gear22of the second gear arrangement first shaft20aand the other one of the two further gears24,25is coupled to the summation box30. In addition, the second gear arrangement first shaft20ais connected to a power take-off. In the case, the dog clutch22ais disengaged from the second gear arrangement first shaft20a, only the power take-off is powered by the second electric motor2.

The summation box comprises a shaft30a, a summation box first gear32and a summation box second gear31which are permanently engaged with the shaft30a. The shaft30ais further connected with a front output yoke34and a rear output yoke33. Front and rear output yokes33and34are configured to deliver the combined output torque to the wheels of the vehicle.

The first gear11of the first gear arrangement10is meshed with the summation box first gear32. Each of the second gear12of the first gear arrangement10and gear25of the second gear arrangement20are meshed with the summation box second gear32.

The first gear arrangement10is configured to supply a first torque from the first electric motor1via one of the first and second gears11,12to the summation box30. The second gear arrangement20is configured to supply a second torque from the second electric motor2to the summation box30. The summation box30is configured to combine the first and second torques and to output a combined output torque to the front and rear output yokes34and33.

In this embodiment, the second gear12aof the first gear arrangement10and the second gear arrangement first gear22have equal size and form the second gear of the transmission. The first gear11of the first gear arrangement is smaller than gears12aand22and forms the first gear of the transmission. In other words, when the transmission is in first gear, only electric motor1can drive by engaging the first dog clutch11a. In the second gear of the transmission, either electric motor1by engaging clutch12aor electric motor2by engaging clutch22acan drive alone or both electric motors1and2can drive together by engaging both clutches12aand22a. Thus, in the second gear of the transmission both motors1and2can contribute to the output torque, and the load can be divided symmetrically among both motors1and2in order to increase the performance of the transmission.

FIG.2shows schematically a transmission layout according to a second embodiment of the present disclosure. In the second embodiment, the first gear arrangement10and the summation box30are designed as in the first embodiment. The second embodiment differs from the first embodiment in the design of the second gear arrangement20. The second gear arrangement20of the second embodiment is designed similar to the first gear arrangement10.

The second gear arrangement20comprises a second gear arrangement first shaft20aand a second gear arrangement first gear21, wherein the second gear arrangement first gear21can be engaged and disengaged with the second gear arrangement first shaft20avia a second gear arrangement first dog clutch21a. The second gear arrangement20can further comprise a second gear arrangement second gear22which can be engaged or disengaged with the second gear arrangement first shaft20avia a second gear arrangement second dog clutch22a. The second gear arrangement20further comprises a second gear arrangement second shaft23and a second gear arrangement fixed gear set with gears26,27. Gear26is permanently engaged with the second shaft23, whereas gear27is permanently engaged with the first shaft20a. Gears26and27are meshed with one another such that the second gear arrangement first shaft20ais coupled to the second gear arrangement second shaft23via the second gear arrangement fixed gear set26,27.

Each of the first gear arrangement first gear11and the second gear arrangement first gear21are meshed with gear32of the summation box30. Moreover, each of the first gear arrangement second gear21and the second gear arrangement second gear22are meshed with gear31of the summation box30.

In this embodiment, the first gear11of the first gear arrangement10and the second gear arrangement first gear21have equal size and form the first gear of the transmission. The second gear12aof the first gear arrangement10and the second gear arrangement first gear22have equal size, are bigger than gears11and21, and form the second gear of the transmission. In other words, either electric motor1by engaging clutch11aor electric motor2by engaging clutch21acan drive alone or both electric motors1and2can drive together by engaging both clutches11aand21ain the first gear of the transmission. And either electric motor1by engaging clutch12aor electric motor2by engaging clutch22acan drive alone or both electric motors1and2can drive together by engaging both clutches12aand22ain the second gear of the transmission. Thus, in the first as well as in the second gear of the transmission both motors1and2can contribute to the output torque, and the load can be divided symmetrically among both motors1and2in order to increase the efficiency of the transmission. With both electric motors1,2being configured to drive in first gear, the maximum output torque of the transmission can be increased.

FIG.3shows schematically a transmission layout according to a third embodiment of the present disclosure. The third embodiment is similar to the second embodiment. However, the third embodiment differs from the second embodiment by including a third gear arrangement50connected to the shaft30aof the summation box30and an inter-axle differential60.

Each of the first gear arrangement first gear11and the second gear arrangement first gear21are meshed with gear32of the summation box30. Moreover, each of the first gear arrangement second gear12and the second gear arrangement second gear22are meshed with gear31of the summation box30. In the first to third embodiments, summation box gear31is smaller than summation box gear32.

In this embodiment, the first gear11of the first gear arrangement10and the second gear arrangement first gear21have equal size and form the first gear of the transmission. The second gear12of the first gear arrangement10and the second gear arrangement second gear22have equal size, are bigger than gears11and21, and form the second gear of the transmission. In other words, in the first gear of the transmission, electric motor1can drive alone by engaging clutch11aand via summation box gear32, or electric motor2can drive alone by engaging clutch21aand via summation box gear32, or both electric motors1and2can drive by engaging both clutches11aand21avia summation box gear32. In the second gear of the transmission, electric motor1can drive alone by engaging clutch12aand via summation box gear31, or electric motor2can drive alone by engaging clutch22aand via summation box gear31, or both electric motors1and2can drive by engaging both clutches12aand22avia summation box gear31. Thus, in the first as well as in the second gear of the transmission, both motors1and2can contribute to the output torque. Due to the coupling to different summation box gears in the first and second gear of the transmission, the load can be divided among both electric motors1and2which can increase the efficiency of the transmission.

The third gear arrangement is a 2-speed gear arrangement with wet clutches. The two further gears51,52can be selectively engaged and disengaged via the wet clutches51a,52awith the shaft30aof the summation box30. The gear ratios51,52apply to both electric motors1,2. For some applications these additional speed ratios can be useful to reach higher speeds or torques. The wet clutches51a,52aallow powershifting in the additional gears51,52. Nevertheless, if the application allows some gear shifts to occur with an output torque dip, alternatively also dog clutches or synchronizers or other kind of clutches can be used here. As a further alternative, the third gear arrangement can be one single gear ratio without clutches in a basic configuration.

Via the third gear arrangement50, the summation box is coupled to an inter-axle differential60. The inter-axle differential60has a lock-up function provided by a wet clutch. Alternatively, other clutches, as for instance a dog clutch, can be selected as well.

In the following, a control method for controlling the dual-motor electric transmission according to the first embodiment to perform a gear shift from a first gear11to a second gear12in the first gear arrangement1without output torque dip is described. The second gear arrangement2has only one gear ratio towards the output, while the first gear arrangement1has two gear ratios towards the output. The vehicle application allows for one electric motor in first gear and two electric motors in second gear. In the first gear, the first electric motor1is used to drive the vehicle, while the second electric motor2is off for supplying the power take-off/charging pump power at a sufficient high speed. In second gear the first electric motor1and the second electric motor2are both driving the vehicle. At the beginning of a gear shifting process the first electric motor1is controlled to drive via the first dog clutch11a. Then, the second electric motor2is controlled to synchronize with the second gear arrangement first gear22. Then, the second gear arrangement first dog clutch22ais controlled to engage with the second gear arrangement first shaft20a. Then, the first electric motor1is controlled to reduce the first torque to zero, and simultaneously the second electric motor2is controlled to increase the second torque such that the combined output torque is basically constant. Then, the first dog clutch11ais controlled to disengage from the first gear arrangement first shaft10a. Then, the first electric motor1is controlled to synchronize with the first gear arrangement second gear12. Then, the second dog clutch12ais controlled to engage with the first gear arrangement first shaft10a. Then, the second electric motor2is controlled to decrease the second torque, and simultaneously the first electric motor1is controlled to increase the first torque such that the combined output torque is basically constant.

FIG.4shows different transmission output torque curves depending on the transmission output speed. The continuous curves71,72and74represent continuous torque of one electric motor in second gear, two electric motors in second gear and one electric motor in first gear, respectively. The dotted curves73,75,76represent peak torque of one electric motor in second gear, two electric motors in second gear and one electric motor in first gear, respectively.FIG.5shows different transmission output power curves depending on the transmission output speed. The continuous curves81,82and84represent continuous power of one electric motor in second gear, two electric motors in second gear and one electric motor in first gear, respectively. The dotted curves83,85and86represent peak power of one electric motor in second gear, two electric motors in second gear and one electric motor in first gear, respectively. The first gear continuous torque is represented by the continuous curve74, the second gear continuous torque is represented by the continuous curve72. During shifting the torque of one electric motor is increased to compensate the zero torque of the other electric motor. This is represented by the dotted curve73. As the dotted curve73lies above the curve74and the curve72in the shifting zone, no torque dip is observed during shifting. Hence, the output torque towards the wheels is maintained across the whole vehicle speed range without torque dip. In other words, gear changes are performed by powershifting.

For functional safety reasons, an automatic shift to neutral is required in case of unsafe vehicle conditions. Although normally-open clutches for the first and second gear arrangements10and20may be dog clutches, other technologies may be used. One example are spring-loaded synchronizer clutches. An advantage of using synchronizer clutches is that the electric motor synchronization can be less accurate which simplifies the electric motor control.

FIGS.1-3show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.

Throughout this specification relative language such as the words ‘about’ and ‘approximately’ may be used. Unless otherwise specified or described, this language seeks to incorporate at least 10% variability to the specified number or range. That variability may be plus 10% or negative 10% of the particular number specified.

The foregoing description is considered as illustrative only of the principles of the described embodiments. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the described embodiments to the exact construction and processes shown and described herein. Accordingly, all suitable modifications and equivalents may be considered as falling within the scope of the described embodiments as defined by the claims which follow.