FR2976526A1 - Power unit for use in electric car, has driving gears constantly gearing with driven gears, where each pair of driven and driving gears defines gear ratio such that each input shaft includes multiple gear ratios than driving gears - Google Patents

Abstract

The unit (1) has an automatic gear box (12) including two input shafts (2) associated with two electric motors (6) such that the gear box is coupled with the motors. Each input shaft supports a set of driving gears (4). A secondary shaft (3) of the gear box supports a set of driven gears (5), and is intended to cooperate with a crown wheel (9). The driving gears of each input shaft constantly gears with the driven gears of the secondary shaft. Each pair of the driven gears and the driving gears defines gear ratio such that each input shaft includes multiple gear ratios than the driving gears. An independent claim is also included for a method for managing a power unit.

Description

The present invention relates to a powertrain, a vehicle equipped with this powertrain and a method of managing this powertrain. In a manner known per se, a gearbox comprises an input shaft connected to the output shaft of a motor, and an output shaft possibly connected by a differential to the driving wheels of a vehicle, for example. The input shaft and the output shaft comprise a plurality of gears. These gears are intended to mesh in order to define several possible ratios of the torque of the input shaft to the output shaft. These ratios of reduction make it possible to define the different speeds of a vehicle. Conventionally, the pinions of the output shaft and the input shaft are in the form of pairs. Each pair of sprockets has a pinion mounted crazy on the shaft supporting it. Gear ratio selection means are used to select and secure an idle gear of the shaft supporting it so that the torque of the input shaft is effectively transmitted to the output shaft via the pair of gears to which belongs this crazy gear.

FIG. 1 illustrates an example of a conventional gearbox architecture 100 comprising an input shaft 101 and an output shaft 102, each supporting gears 103. In the example of FIG. 1, gears 103 supported by output shaft 102 are mounted idle (free in rotation relative to the axis of the output shaft 102); the pinions 103 supported by the input shaft 101 are integral with the latter. The gearbox 100 comprises five gear ratios corresponding in this case to the number of gear pairs 103. Synchronizers 104, which conventionally are slidable along the axis supporting them, are arranged between the gears 103. mounted idle on the output shaft 102. These synchronizers moving in contact with one of these idle gears allow to secure the shaft and actually engage the input shaft 101 and the output shaft 102, in order to transmit to the latter a torque function including the gear ratio selected. One of the drawbacks of these conventional gearboxes is the breakage of torque occurring during transmission ratio changes. This is reflected in the driving of the vehicle by jolts during shifts. In an attempt to reduce the effects, so-called dual-clutch gearboxes have been designed. These gearboxes have the particularity of having a clutch system between the input shaft and two coaxial primary shafts, one being generally hollow and traversed by the other. These primary shafts mesh with secondary shafts cooperating with the output shaft of the gearbox. A first secondary shaft includes the gears for defining the even gear ratios, a second sub shaft includes the gears for defining the odd gear ratios. The double clutch can be used to engage one of the primary shafts alternately with the input shaft. When a speed, for example pair, is engaged, this gearbox makes it possible to preselect the next (odd) speed by engaging the corresponding gears. However, this odd speed ratio is not engaged because the primary shaft through which the transmission is made is disengaged. The passage of the even speed to the odd speed is effected by the simultaneous disengagement of the primary shaft allowing the transmission of the even speed ratio and the clutch of that allowing the transmission of the odd following speed ratio. Because of its preselection, this odd speed ratio is thus quickly engaged, which tends to reduce the torque failure existing at the passage from one speed to another. However, such gearboxes only offer the possibility of reducing the effects of torque failures without, however, completely preventing them, since there is a short period of time during the gear shifting during which the torque of the gearbox The input is not transmitted to the output shaft (with the desired gear ratio). In addition, given the scarcity of fossil fuel resources, electrically propelled vehicles are becoming more and more common. These electric vehicles can sometimes move at selected speeds from a very wide range of possible travel speeds. If necessary, there is a real need to benefit from a gear ratio between the electric motor propelling the vehicle and the wheels of the latter, to cover this wide range of travel speeds. Here too, there is the problem of the break-up of a couple.

Also the present invention aims to overcome all or part of these disadvantages by providing a powertrain to shift the gears with a torque profile to the continuous wheels, that is to say, smoothly during the phases of change of speed.

For this purpose, the subject of the present invention is a powertrain characterized in that it comprises at least two engines and a gearbox, the gearbox comprising: (i) at least two primary shafts each associated with one of the engines , so that the gearbox is coupled to as many motors as comprises primary shafts, each primary shaft supporting a plurality of drive gears, (ii) at least one secondary shaft, supporting a plurality of driven gears , intended to cooperate with a differential ring gear, the drive gears of each primary shaft meshing constantly with the pinions of a secondary shaft, each pair of driven pinion and pinion gear defining a gear ratio, so that each primary shaft includes as many gear ratios as it includes drive gears. The powertrain according to the invention thus makes it possible to prevent torque ruptures, each primary shaft being associated with a motor and being able to transmit independently of the other primary shafts a torque corresponding to the gear ratio selected for this shaft. Its use in an electric vehicle makes it possible to increase the output torque of the motors to cover a very wide range of possible speeds of the vehicle. According to another characteristic of the powertrain according to the invention, each primary shaft comprises gear ratios identical to the gear ratios of the other primary shafts. According to yet another characteristic of the powertrain according to the invention, each primary shaft comprises an identical number of driving gears and the gearbox comprises a number of gear ratios equal to the product of the number of primary shafts and 15 20 drive gears that includes each primary shaft, which is subtracted from the number 1. Preferably, the driven gears are integral with the secondary shaft supporting them, the drive gears are mounted idle on the primary shaft supporting them, and the gearbox comprises means for selecting the gear ratio of each primary shaft. The transmission means comprise synchronizers and / or multi-disk clutches and / or claws. Advantageously, the gearbox is automatic.

According to yet another characteristic of the powertrain according to the invention, at least one of the motors is electric. Preferably, each motor is electric. This embodiment is particularly advantageous because of the compactness of the electric motors compared to the heat engines.

In the space occupied by an electric car, it is thus possible to provide several engines. The powertrain according to the invention is thus compatible with the current dimensions of a car. According to yet another characteristic of the powertrain according to the invention, it comprises a single secondary shaft. The invention also relates to a vehicle comprising a powertrain having the above characteristics. The subject of the invention is also a method for managing a power unit having the aforementioned characteristics, making it possible to maintain the linearity of the torque at the output of the gearbox during a gear ratio change, characterized in that comprises the steps of: selecting a gear ratio for a first primary shaft and a second primary shaft, so that the first primary shaft and the second primary shaft each contribute to the multiplication of a torque at the output of the box of speeds, - deselect the gear ratio of the first input shaft, while maintaining the gear ratio of the second input shaft selected, so that only the second input shaft 35 contributes to the reduction of the torque at the output of the gearbox, - adjust the motor torque associated with the second primary shaft to maintain linearity the torque at the output of the gearbox despite the absence of torque reduction by the first input shaft, - adapt the operating speed of the engine associated with the first input shaft according to the new gear ratio which will be selected for the first primary shaft in the next step, in order to adapt the speeds of the first primary shaft and the secondary shaft, - select the new gear ratio for the first primary shaft, so that the first primary shaft and the second primary shaft again contribute to the multiplication of a torque output of the gearbox, but with a new gear ratio. The method further comprises, if necessary, the additional steps of repeating the preceding steps to change the gear ratio again, but by reversing the roles of the first and second primary shafts and their associated engines respectively. . Other features and advantages of the invention will become apparent from the detailed description given below, taken in conjunction with the various appended drawings illustrating by way of example the principles of the present invention, in which: FIG. 1 is a view schematic of the architecture of a gearbox belonging to the state of the art, - Figure 2 is a front view of a powertrain according to an embodiment of the present invention, - Figure 3 is a perspective view of a powertrain according to an embodiment of the present invention, - Figures 4, 5, 6 and 7 are schematic views of a powertrain according to several particular embodiments of the invention having in common the presence of a single secondary shaft, - Figures 8 and 9 are schematic views of a powertrain according to several particular embodiments of the invention having in common the 10, 11 and 12 are side views of a powertrain according to a particular embodiment marking different successive stages of a gear ratio change.

Figures 2 and 3 show a power train 1 according to an embodiment of the present invention. The powertrain 1 comprises in the example of Figures 2 to 12 at least two engines 6 and a gearbox 12. The gearbox 12 comprises two primary shafts 2. It can of course comprise more than two primary shafts 2. From quite advantageously, each primary shaft 2 is associated with one of the motors 6. Thus, the gearbox is coupled with as many motors 6 that it comprises primary shafts 2. The primary shaft 2 is connected to the output shaft of the engine 6 with which it is associated. The primary shafts 2 can be parallel to each other, as is the case in FIG. 4 for example. The gearbox 12 furthermore comprises a secondary shaft 3. In the example of FIGS. 4 to 7, it comprises a single secondary shaft 3. In the example of FIGS. 8 and 9, it comprises two secondary shafts 3, which is as much of secondary trees 3 that it comprises primary trees 2.

Each primary shaft 2 supports a plurality of drive gears 4 and each secondary shaft 3 supports a plurality of driven gears 5. Each drive gear 4 meshes constantly with a driven gear 5. In the examples of the different figures, all the gears 4 of the same primary shaft 2 meshing with driven gears 5 of one and the same primary shaft. In other words, in the examples of the various figures, a primary shaft 2 is coupled to a single secondary shaft 3. Each pair of gears thus defines a gear ratio. A primary shaft 2 comprising n drive gears 4 thus comprises n possible gear ratios. It is possible to combine the gear ratios of several primary shafts 2 to achieve a particular gear ratio. Thus, for two primary shafts 2 including n gear ratios, it is possible to achieve n2 combinations of gear ratios, n2 gear ratios. The gear ratios of the different primary shafts 2 may be identical. Thus, with reference to the example of FIG. 10, the gear ratio 1G of the primary shaft 2 located on the left in the figure is identical to the gear ratio 1D of the primary shaft 2 located on the right-hand side of the Fig. Similarly can be equal ratios of 2G and 2D ratios visible in the same figure.

Preferably, for a given gear ratio of a first primary shaft 2, the possible gear ratios of the second main shaft 2 are limited to the same gear ratio and the gear ratio immediately higher or immediately lower. Thus, for a gearbox 12 comprising two primary shafts with n drive gears 4 each, the number of possible combinations can be limited to 2n-1. The gearbox 12 then comprises 2n-1 possible gear ratios. In the embodiments shown in FIGS. 2 to 12, the driven gears 5 are integral with the secondary shaft 3 which supports them, and the drive gears 4 are mounted idle on the primary shaft 2 supporting them. The powertrain 1 comprises means for selecting a gear ratio of each primary shaft 2. These selection means comprise for example a synchronizer 7 placed in each space defined between two successive drive gears 4 of a primary shaft 2 Each synchronizer 7 is able to move along the primary shaft 2 on which it is located in order to secure the movement of a drive gear 4, mounted crazy, with that of the primary shaft 2 supporting it. It is also possible to provide one or more driven gears 5 mounted idle on the secondary shaft supporting them and corresponding drive gears integral with their primary shaft 2. Synchronizers 7 can then be arranged on each of the secondary shafts 3 comprising a or several crazy gears. Instead of synchronizers 7, it is also possible to use multidisc clutches or claws. As can be seen in most of the figures, each secondary shaft 3 can support a pinion gear 8 intended to mesh with a differential ring 9 of a differential gear 10 transmitting the desired torque to one or more output shafts 11. pinion 8 can be arranged between two driven gears 5 or at the end of secondary shaft 3.

Each motor 6 can operate at a different speed and is electronically programmed to give maximum torque linearity to the wheels of a vehicle equipped with the powertrain 1 according to the invention. It is thus possible for a single motor 6 to operate, the other motor (s) 6 being at a standstill. This operating mode is adapted for example for low torque values required at the output of the gearbox 12. When high torque values are required, for example when starting a vehicle equipped with the powertrain 1, several engines 6 can work simultaneously so that the primary shaft 2 with which they are associated contributes to the reduction of a torque output of the gearbox 12. During gear changes, simply keep at least one primary shaft 2 in mesh with a secondary shaft 3 to prevent breaks in torque. Indeed, the time to select a new gear ratio for a first primary shaft 2, the second main shaft 2 continues to transmit the required torque output of the gearbox 12. To this end, the motors 6 can be programmed to adapt their torque and maintain the linearity of the torque output of the gearbox 12. Advantageously, the motors 6 are electric. The primary shaft 2 with which they are associated can merge with their output shaft. The engines 6 can also be heat engines. In this case, it is necessary to provide a clutch between each motor 6 and the primary shaft 2 with which it is associated. An embodiment in which the power train 1 comprises both an electric motor 6 and a thermal engine 6 is possible. The gearbox 12 may be automated and include a control mechanism comprising hydroelectric actuators or a common cylinder actuator. The present invention also relates to a powertrain management method 1 to maintain the linearity of the torque output of the gearbox 12 during gear shifts. The various stages of a gear ratio change are represented in the chronological order of FIGS. 10 to 12 (the arrows illustrate the selected gear ratios and the transmission of a torque, as a function of the combination of gear ratio selected on the primary shafts, at the output of the gearbox 12). The method comprises the steps of: - selecting a gear ratio for a first primary shaft 2a and a second primary shaft 2b, so that the first primary shaft 2a and the second primary shaft 2b each contribute to the reduction of a torque at the output of the gearbox 12, - deselect the gear ratio of the first input shaft 2a, while keeping the gear ratio of the second input shaft 2b selected, so that only the second input shaft 2b contributes to the reduction of a gearbox torque at the output of the gearbox 12, - adapting the operating torque of the engine 6 associated with the second input shaft 2b in order to maintain the linearity of the torque at the output of the gearbox 12 despite the absence of torque reduction by the first primary shaft 2a, - adapt the operating speed of the motor 6 associated with the first primary shaft 2a ction of the new gear ratio which will be selected for the first primary shaft 2a in the next step, in order to adapt the speeds of the first primary shaft 2a and the secondary shaft 3, - select a new gear ratio for the first primary shaft 2a, so that the first primary shaft 2a and the second primary shaft 2b each again contribute to the reduction of a torque at the output of the gearbox 12, with a new gear ratio. The method may further comprise, if appropriate, the additional steps of repeating the steps detailed above to change the gear ratio again, this time reversing the roles of the first primary shaft 2a and the second main shaft 2b and the motors. 6 respectively associated with them. Thus, it is the first primary shaft 2a which will continue to transmit torque at the output of the gearbox 12 and it is the engine 6 associated with it which will see its speed be adapted to maintain the linearity of torque at the output of the gearbox 12. the gearbox 12 during deselection of the gear ratio of the second primary shaft 2b until the selection of a new gear ratio for the second primary shaft 2b.

Although the invention has been described in connection with particular embodiments, it is obvious that it is in no way limited and that it includes all the technical equivalents of the means described and their combinations if they come within the scope of the invention.5

Claims (12)

REVENDICATIONS1. Power train (1) characterized in that it comprises at least two engines (6) and a gearbox (12), the gearbox (12) comprising: (i) at least two primary shafts (2) associated each to one of the motors (6), so that the gearbox (12) is coupled to as many motors (6) as it comprises primary shafts (2), each primary shaft (2) supporting a plurality of drive gears (4), (ii) at least one secondary shaft (3) supporting a plurality of driven gears (5) for cooperating with a differential ring gear (9), the drive gears (4), ) of each primary shaft (2) constantly meshing with the gears of a secondary shaft (3), each pair of drive pinion (4) and driven gear (5) defining a gear ratio, so that each primary shaft (2) comprises as many gear ratios as it includes drive gears (4). 2. Power train (1) according to claim 1, characterized in that each primary shaft (2) comprises gear ratios identical to the gear ratios of the other primary shafts (2). 3. Power train (1) according to claim 1 or claim 2, characterized in that each primary shaft (2) comprises an identical number of drive gears (4) and in that the gearbox comprises a number of gear ratios equal to the product of the number of primary shafts (2) and drive gears (4) contained in each primary shaft (2), to which is subtracted the number 1. 30 4. Power train (1) according to one of claims 1 to 3, characterized in that the driven gears (5) are integral with the secondary shaft (3) supporting them, the drive gears (4) are mounted on the primary shaft (2) supporting them, and in that the gearbox 35 comprises means for selecting the gear ratio of each primary shaft (2). 5. Powertrain (1) according to claim 4, characterized in that the transmission means comprise synchronizers and / or multi-disk clutches and / or claws. 6. Power train (1) according to one of claims 1 to 5, characterized in that the gearbox is automatic. 7. Power train (1) according to one of claims 1 to 6, characterized in that at least one of the motors (6) is electric. 8. Powertrain (1) according to claim 7, characterized in that each motor (6) is electric. 15 9. Powertrain (1) according to one of claims 1 to 8, characterized in that it comprises a single secondary shaft (3). 10. Vehicle characterized in that it comprises a powertrain (1) according to one of claims 1 to 9. 20 11. A method of managing a powertrain (1) according to any one of claims 1 to 9 for maintaining the linearity of the torque output of the gearbox during a gear ratio change, characterized in that it comprises the steps of: - selecting a gear ratio for a first primary shaft (2a) and a second primary shaft (2b), so that the first primary shaft (2a) and the second primary shaft (2b) contribute each at the reduction of a torque at the output of the gearbox (1), 30 - deselect the gear ratio of the first input shaft (2a), while maintaining the gear ratio of the second input shaft (2b) selected, so that only the second primary shaft (2b) contributes to the reduction of the torque at the output of the gearbox (1), 35 - adapt the operating torque of the engine (6) associated with the second shaft primary (2b) in order to maintain the linearity of the torque at the output of the gearbox (1) despite the absence of torque reduction by the first input shaft (2a), - to adapt the operating speed of the motor (6) associated with the first primary shaft (2a) according to the new gear ratio that will be selected for the first primary shaft (2a) in the next step, to adapt the regimes of the first primary shaft (2a) and the secondary shaft (3), - selecting a new gear ratio for the first primary shaft (2a), so that the first primary shaft (2a) and the second primary shaft (2b) each again contribute to the reduction of a torque at the output of the gearbox (1), but with a new gear ratio. 12. Method according to claim 11, characterized in that it comprises the additional steps of repeating the preceding steps to change the speed ratio again, but by reversing the roles of the first primary shaft (2a) and the second primary shaft. (2b) and motors (6) respectively associated with them.