FR2997047A1 - Device for motorizing vehicle i.e. electric vehicle, has control unit for controlling rotational speeds of electrical motors to use motors at high speeds above predetermined threshold speed during entire operation of vehicle - Google Patents

Abstract

The device (10) has a planetary gear (1) comprising a satellite carrier (2) that is coupled to an output shaft (8). The output shaft is linked to wheels of a vehicle. A solar pinion (4) is coupled to an electrical motor (11). An outer ring (3) is coupled to another electrical motor (12). A control unit controls rotational speeds of the electrical motors to use the motors at high speeds above the predetermined threshold speed during the entire operation of the vehicle. Immobilization devices (61, 62) immobilize the solar pinion and the outer ring, respectively. An independent claim is also included for a method for controlling a device that motorizes a vehicle with electric propulsion.

Description

The present invention relates to motorization devices for electric vehicles, that is to say to drive the electric wheels. The term "wheel drive vehicle" means an electric traction vehicle or an electrically propelled vehicle, using an electric traction chain. It relates more particularly to a motorization device and a control method for an electric vehicle in which the driving of the wheels is carried out exclusively by means of one or more electric motors. In the prior art, it is known to have an electric motor for driving a two-wheel axle 15 with a differential. It is also known to arrange a specific electric motor for each wheel. Moreover, the efficiency of an electric motor varies with the rotational speed (and the torque) at which it is driven, which remains true with the brushless motors 20 (brushless motor) recently used for electric traction. In particular, the efficiency of the motor is no longer optimal when the rotational speed of the motor is in a range of intermediate values or in a range of low values, which is disadvantageous in the case of vehicles making frequent stops, such as buses, road vehicles, handling equipment, delivery vehicles, cars traveling in congested traffic, etc. In a main electric drive vehicle where the vast majority of the energy used is stored in batteries. It is essential to optimize the powertrain performance to either increase the range of the vehicle for a given battery capacity, or to reduce the size and onboard battery capacity required for a given target range. Therefore, the high cost of batteries requires optimizing the performance of the power train to get the most out of the energy stored in the batteries.

It has thus appeared interesting to improve the performance of the power train by optimizing the efficiency of the (or) motor (s) electric (s) used (s) in the power train. According to the present invention, there is provided a drive device for an electric vehicle, comprising a planetary gear and at least two electric motors, the planetary gear comprising a planet carrier coupled to an output shaft, the output shaft being adapted for driving at least one wheel of the vehicle, a sun gear coupled to a first electric motor, an outer ring coupled to a second electric motor, at least one series of satellites engaged with both the sun gear and the outer ring, a control unit for controlling the rotational speed (and torque) setpoints on the first and second electric motors, so as to use said motors in speed ranges above a predetermined speed threshold for the entire range of vehicle speeds possible.

Thanks to these arrangements, the two electric motors can be made to work in a range of rotational speed and torque for which the efficiency is higher. Indeed, it avoids using the motors in ranges of low rotation speeds: the efficiency of the traction chain is thus improved. In various embodiments of the invention, one or more of the following may also be used: the device may further comprise a first immobilization device adapted to immobilize the device; solar gear; whereby the immobilization of the sun gear is carried out simply and does not consume energy; - The device may further comprise a second immobilizer adapted to immobilize the outer ring; whereby the immobilization of the crown is carried out simply and does not consume energy; each of the first and second immobilizers may be a belt brake; which is a robust, reliable and space-saving solution; each of the first and second immobilization devices may comprise a clutch adapted to interfere with the sun gear 15 and the outer ring respectively; which is also a robust and reliable solution; the first and second immobilization devices can be arranged side by side; which makes it possible to improve the integration of the two brakes in the device; the two motors are arranged coaxially on the same axis; so that the radial space is limited and the meshing losses are limited; the axes of the two motors are distinct and the motors are devoid of axial shaft penetrations; whereby standard and inexpensive engines can be used; - the planetary gear is a planetary gear with simple satellites; so that the cost of the solution is controlled; the device is devoid of mechanical coupling with a heat engine; so that the motorization solution remains simple and inexpensive; the device may drive two wheels of an axle, and may comprise a differential interposed between the sun gear and said wheels, the planet carrier of the sun gear forming the satellite door of said differential; whereby one can mechanically integrate the differential with the planetary gear; - The device may comprise a interconnection system to secure the elements of the sun gear, so that all the elements of the planetary gear rotate at the same speed; the torque transmission which can be optimized for high speeds.

The invention furthermore relates to a method for controlling a drive device for an electrically propelled vehicle, comprising a planetary gear and at least two electric motors, the planetary gear comprising: a carrier coupled to an output shaft , the output shaft being adapted to drive at least one wheel of the vehicle, - a sun gear coupled to a first electric motor, - an outer ring coupled to a second electric motor, the method comprising at least: - a phase during which one of the motors is at zero speed and the other is driven, a phase during which the motors are controlled in opposite directions relative to each other. According to one aspect of the invention, the method may further comprise one of the following phases: a phase during which the motor driving the crown is at zero speed and the other driven, a phase during which the motor driving the Solar gear is at zero speed and the other driven, - a phase during which both engines are controlled in the same direction. Other aspects, objects and advantages of the invention will become apparent on reading the following description of two of its embodiments, given by way of nonlimiting examples with the aid of the attached drawings in which: FIG. 1 shows a schematic diagram of the traction chain of an electric vehicle according to the invention; FIG. 2 schematically represents the mechanical architecture of the motorization device according to one embodiment of the invention, FIG. FIG. 4A and 4B show timing diagrams for each of the two motors of the device; FIG. 6 is a schematic representation of a second embodiment of the invention; FIGS. 7A-7D show schematic speed diagrams of the planetary gear; 8, schematically represents an associated control system diagram; FIG. 9 illustrates a variant of the second embodiment. In the different figures, the same references denote identical or similar elements. Figure 1 schematically shows a traction chain of an electric vehicle. The vehicle in question may be a four-wheeled vehicle, a three-wheeled vehicle, or a vehicle with more than four wheels; at least one of these wheels is a driving wheel. The notions of electric traction electric propulsion will not be distinguished in this document. The driving wheel or wheels are set in motion by the traction chain. The traction chain comprises at least one electric accumulator battery 50, which may be of any type, in particular Li-Ion, lithium polymer or other. The traction chain comprises at least one control unit 52 in charge of controlling a drive device 10 which notably comprises traction motors. To control the drive device, the control unit 52 receives instructions 83,84 from the user of the vehicle or other control system not shown. A rotating shaft 8 constitutes the output of the motorization device 10, intended for one or more wheels 55 of the vehicle. In the case where the drive device drives two wheels of an axle that can rotate at different speeds, a differential 58 will be inserted between the output shaft 8 and the wheel shaft 8a. In another configuration where the drive device 10 drives a single wheel, the drive device 10 can be integrated with the wheel to form a motorized wheel. A power supply 51 connects in known manner the battery 50 to the control unit 52; control signal connections 53 connect the control unit 50 in a known manner to the members contained in the motorization device 10 which will be described hereinafter. Advantageously according to the invention, the motorization device 10 is devoid of mechanical coupling with a heat engine. With reference to FIG. 2, the motorization device 10 comprises a planetary gear train 1 of main axis X and two electric motors 11, 12 also referenced M1 and M2. The planetary gear 1 comprises the following main elements: - a planet carrier 2 coupled to the output shaft 8 and pivotally mounted about the main axis X, - a sun gear 4 coupled to the first electric motor 11, also mounted pivoting about the main axis X, the coupling between the sun gear 4 and the first electric motor that can be direct or indirect, - an outer ring 3 coupled to the second electric motor 12, also pivotally mounted about the main axis X , the coupling between the outer ring 3 and the second electric motor can be direct or indirect, - at least one series of satellites 23 in engagement with both the sun gear 4 and an internal toothing 30 of the outer ring 3.

Advantageously according to the invention, it is a single planetary gear simple satellites, which is a configuration well known in the industry and inexpensive. In addition, in the example shown, the motorization device comprises a first immobilization device 61 adapted to immobilize (or at least brake) the sun gear by means of a rim 40 integral with the sun gear and a second gear device. immobilization 62 adapted to immobilize (or at least brake) the outer ring. The integral rim 20 of the sun gear and the outer ring have substantially the same diameter. Thus, according to a particular aspect of the invention, the two immobilizers can be arranged next to each other, at the same radial distance from the X axis, for the sake of optimized integration. In the example illustrated here, the immobilizers are made in the form of a belt brake. This type of belt brake, where a band is tightening a rotating cylindrical portion from the outside, is known in the art and therefore not described in detail here. It should be noted that, to cause the immobilization of the outer ring 3 or the immobilization of the sun gear 4, it would be possible, instead of using the brakes illustrated here, to control the corresponding electric motor 35 to maintain a speed zero or extremely low rotation. In an alternative not shown, each of the immobilizing devices could be a jaw clutch system with a movable finger adapted to interfere respectively with the outer ring 3 or with the rim 40 integral with the sun gear. This type of clutch device being known, it will not be described in detail here. In the example illustrated in Figure 2, the output shaft 8 passes through an axial recess 120 of the second motor M2, centered on X. In this case, the two motors are arranged coaxially on the same axis (X). This constitutes a low radial architecture, and which may have industrialization advantages, or integration advantages in an autonomous motorized wheel type configuration. According to a variant of architecture shown in FIG. 3, it is also possible to arrange the second electric motor M2 at a distance from the main axis X. In this case, it is preferable to use electric motors without axial recess passing through, which is the most widespread and least expensive configuration. The axes X1, X2 of the two motors Ml, M2 are then distinct. In the example illustrated, an intermediate gear 35 is used to drive the crown 3 from the second motor M2; we will take care to take into account, in the control logic, the reversal of the direction of rotation of this intermediate stage. The traction chain and the drive device 30 operate as follows. With reference to FIGS. 7A-7D, the following equations govern the rotational speeds and linear velocities of the various elements: V1 = R1.w1, where V1 is the speed of a point outside the pitch circle of the solar gear 4, equal to the speed an adjacent corresponding point of the satellite 23, R1 being the pitch radius of the sun gear and 01 being the rotational speed of the sun gear 4, V2 = R2.w2 V2 being the speed of an inner point of the pitch circle of the ring gear 3 , equal to the speed of an adjacent corresponding point of the satellite 23, R2 being the original inner radius of the ring and w2 being the rotational speed of the ring 3, the speed of the axis of the satellite 23 can then be written : Vs = + R2.co2) / 2, and therefore the speed of rotation of the satellite gate 2 is expressed as follows: ws = Vs / Rs = (R1.01 + R2.w2) / 2Rs, where Rs is the radius where is the axis of the satellites and ws the speed of rotation of the planet carrier, which corresponds to the rotational speed of the output shaft 8. As will be seen below, and as illustrated in FIGS. 4A-4B and 7A-7D, four main phases of operation described below can be distinguished according to the operating mode. desired rotation on the output shaft 8, namely the phases 1 to 4. Phase 1 To generate a zero speed or a first low speed range, the two motors M1, M2 are driven in the opposite direction (cf. Figure 7C). More precisely, to obtain a zero velocity on the output shaft 8, the velocities w1 and w2 are chosen such that the resultant R1.01 + R2.w2 is zero. According to one possibility illustrated in FIG. 4A, 02 positive and negative w1 are chosen. According to another possibility illustrated in Figure 4B, one can just as well choose wl positive and 02 negative. Col and co2 are also chosen so that the values col and (o2 are outside the areas ZLEpos and ZLEneg of suboptimal efficiency (see Fig. 4A-43). output increases, so we change the velocity col and co2 to make the resultant R1.01 + R2.02 increases.In the case of Figure 4A, we reduce the regime w1 to positive values and we can at the same time In the case of FIG. 4B, one increases the speeds col to the positive values and one can at the same time decrease the absolute value regime of 02.

Phase 2 To generate a second range of intermediate speeds, the motor M1 is made to work alone, while immobilizing the ring gear 3, the motor M2 then being at rest at zero speed. In this phase (see FIG. 7B), the second immobilizing device 62 is therefore biased to immobilize the ring gear 3. In this 'phase 2' configuration, according to the choice of dimensions for R1, R2, R3, a ratio will be obtained. col / cos (equal to 2 Rs / R 1) typically between 2.5 and 3.3, and a ratio of 2.9 will preferably be chosen. Phase 3 To generate a third range of higher intermediate speeds, the motor M2 is operated alone while immobilizing the sun gear 4, the motor M1 then being at rest at zero speed. In this phase (see FIG. 7A), the first immobilizing device 61 is therefore biased to immobilize the sun gear 4. In this 'phase 3' configuration, according to the choice of dimensions for R1, R2, R3, we will obtain a ratio w2 / cos (equal to 2Rs / R2) typically between 1.2 and 2 and a ratio of 1.6 will preferably be chosen. Phase 4 To generate a fourth range of speeds corresponding to the highest speeds for the vehicle, the motors M1, M2 are operated in conjugation in the same direction as shown in FIG. 7D, the immobilizers then being inactive.

In this configuration phase 41, to optimize the transmission of power from each of the two motors Ml, M2 to the output shaft 8, it is further possible to provide a mutual interconnection system, which will be described in detail later with reference in Figure 9, and which makes it possible to join in rotation the sun gear 4 with the planet carrier 2 so that all the elements of the sun gear 1 rotate at the same speed. Transitions between phases For transitions to one of the phases requiring immobilization of the ring gear 3 or the sun gear 4 (phase 2 or phase 3), the corresponding motor is driven towards the zero speed and then the immobilizer is activated. corresponding. As represented in FIG. 5, for any desired vehicle speed corresponding to a speed ws, the rotational speeds of the motors M1, M2 are in a zone of optimum efficiency 80, and are not in a zone of sub-optimal efficiency. ZLEpos, even at a low vehicle speed or close to zero. It should be noted that the efficiency values which appear in FIG. 5 illustrate the degradation of the performance performances in the low speed ranges, in particular between 0 and 500 rpm, also between 0 and 1000 rpm, and again between 0 and 1500 rpm. We can choose a speed threshold of 1250 rpm for the excluded zone ZLEpos, or as in the example illustrated in FIG. 5, it can be an area with a curved boundary on the right, a boundary corresponding to a yield of 90% for example.

It is precisely these low speed ranges that are frequently traveled by vehicles in the city such as taxis, buses, delivery vehicles, trams, garbage trucks, which are vehicles for which electric traction is particularly appropriate. According to an advantageous advantageous arrangement of the invention aimed at driving an axle, a differential 58 may be associated with the planetary gear 1 already described as illustrated in FIG. 6. A first wheel shaft 8 a connects one of the output gears of the differential to a first wheel, and a second wheel shaft 8b connects the other of the output gears of the differential to the other wheel, passing through the first motor M1 through a through axial recess 110 of X axis. illustrates the diagram of the associated control system. The control unit 52 receives a power supply 81, speed instructions 83 and torque 84 representative of the will of the driver or an autopilot system. Furthermore, the control unit 52 acquires the speed of rotation of the first motor M1 by means of the sensor 85 the speed of rotation of the second motor M2 by means of another sensor 86. Thanks to this input information and the laws of including the speed control logic described above, the control unit 52 delivers the appropriate torque and speed setpoints to the motors M1 and M2, and delivers activation signals F1, F2 for each of the means of immobilization 61,62.

If the mutual interconnection system is present, a signal Cl allows the control unit to control said interconnection. Figure 9 illustrates two optional features of the operator device. The first is a variant of FIG. 6 in which the second motor M2 is arranged axially, its axis X2 coinciding with X. In this case, the rotor comprises a through axial recess 120 which allows an output half-shaft 8a. of the differential to cross. It is thus possible to obtain a very compact solution whose radial size is reduced, which facilitates its implementation. The other optional feature relates to the mutual interconnection system 7 which comprises a rotating clutch 71 axially slidably mounted on a crenellated outer cylindrical surface 27 of the planet carrier. This rotating clutch 71 can engage on a crenellated outer cylindrical bearing surface 47 of the pinion. Solar energy agnecée vis-à-vis. This rotating dog 71 can be moved by a control fork 73 mounted to slide axially on a guide rod 72. When the fork 73 is positioned to the left the clutch 71 does not interfere with the sun gear 4 and there is no locking effect or interconnection; on the other hand, when the fork 73 is positioned on the right, the clutch 71 secures the sun gear 4 with the planet carrier 2, which has the effect of imposing a rotational speed common to all the elements of the sun gear train 1. Of course , we will drive this mutual interconnection through the return speeds 85.86 to engage the interconnection when the two speeds are close. It should be noted that a specific power speed controller can support the control of the torque setpoints according to speed setpoints developed by the 52.30 control unit.

Claims (12)

REVENDICATIONS1. Motorization device for an electric wheel drive vehicle, comprising a planetary gear (1) and at least two electric motors, the planetary gear comprising: a planet carrier (2) coupled to an output shaft (8), the output shaft being adapted to drive at least one wheel (55) of the vehicle, - a sun gear (4) coupled to a first electric motor (11), - an outer ring (3) coupled to a second electric motor (12), - at least one series of satellites meshing with both the sun gear and the outer ring, - a control unit (52) for controlling the rotational speed or torque setpoints on the first and second electric motors, so as to use said motors in speed ranges above a predetermined speed threshold for the entire vehicle speed range. 2. Motorization device according to claim 1, further comprising a first immobilizer 25 (61) adapted to immobilize the sun gear and a second immobilizer (62) adapted to immobilize the outer ring. The actuator device of claim 2, wherein each of the first and second immobilizers is a belt brake. 4. Motorization device according to claim 2, wherein each of the first and second immobilizer devices (61,62) comprises a clutch adapted to interfere with respectively the sun gear and the outer ring. 5. Motorization device according to one of claims 1 to 4, wherein the two motors are arranged coaxially on the same axis (X). 6. Motorization device according to one of claims 1 to 4, wherein the axes (X1, X2) of the two motors are distinct and the motors are devoid of axial shaft penetrations. 7. Motorization device according to one of claims 1 to 6, wherein the sun gear is a planet gear simple satellites. 8. Motorization device of one of claims 1 to 7, characterized in that it is devoid of mechanical coupling with a heat engine. 20 9. Motorization device according to one of the preceding claims, which drives two wheels of an axle, and which further comprises a differential interposed between the sun gear and said wheels, the planet carrier (2) of the sun gear forming the satellite gate of said differential. 10. Motorization device according to one of the preceding claims, further comprising a system 30 clutch (7) for securing the elements of the planetary gear. 11. A method of controlling a drive device for a vehicle with electric propulsion, comprising a planetary gear (1) and at least two electric motors, the planetary gear comprising: - a planet carrier (2) coupled to an output shaft (8), the output shaft being adapted to drive at least one wheel of the vehicle, - a sun gear (4) coupled to a first electric motor (11), - an outer ring (3) coupled to a second motor electric motor (12), the method comprising at least: - a phase during which one of the motors is at zero speed and the other driven, - a phase during which the motors are controlled in opposite directions with respect to the other. 15 12. Control method according to claim 11, further comprising one of the following phases: a phase during which the motor driving the crown is at zero speed and the other driven, a phase during which the motor driving the solar gear is so at zero speed and the other driven, - a phase during which both engines are controlled in the same direction. 25