Vehicle and method for controlling such a vehicle

Abstract

A vehicle (1) is provided that comprises at least two drive shafts (10, 30) and at least one torque vectoring unit (45) arranged on one of the drive shafts (30), thus forming a torque vectoring shaft. The vehicle is configured to generate a specific torque (T TV The torque vectoring shaft (30) further includes a control unit (50) configured to determine a specific torque (T TV ), the control unit (50) is further configured to: i) reallocate the net vehicle drive torque between the drive shafts (10, 30) by increasing the absolute value of the drive torque (T1) of the torque vectoring shaft (30); and ii) distribute the increased drive torque (T1) of the torque vectoring shaft (30) to the left and right wheels (35a, 35b).

Description

[Technical Field]

[0001] The present invention relates to the technical field of wheeled vehicles and methods of controlling such vehicles, in particular to torque vectoring in vehicles. [Background technology]

[0002] Wheeled vehicles can be multi-axle drive vehicles. One common type is the so-called all-wheel drive (AWD) vehicle. A primary axle provides drive torque to the axle's associated wheels, and when AWD is required, a secondary axle is selectively controlled to also provide drive torque to its associated wheels. This function can be achieved by mechanically coupling the secondary axle to the primary axle so that the drive torque is distributed longitudinally. In hybrid vehicles, an internal combustion engine can drive the front (primary) axle, while the rear (secondary) axle can be driven by one or more electric motors. Such vehicles can be operated as front-wheel drive (FWD), rear-wheel drive (electric RWD), or AWD (FWD+RWD).

[0003] Most modern automobiles are fully electric, meaning that they are provided with one or more electric motors to drive the front axle, the rear axle, or both.

[0004] Vehicles may be equipped with torque vectoring, which is an effective technique for increasing yaw rate damping and improving vehicle stability during driving. Torque vectoring is typically applied to a single axle of the vehicle, allowing for controlled drive torque to each of the left and right wheels.

[0005] There are different types of mechanisms for providing torque vectoring. For example, a torque vectoring axis may be based on superposition, meaning that a differential distributes the drive torque equally, while the torque vectoring mechanism distributes torque from one wheel shaft to the opposite wheel shaft. Such a torque vectoring mechanism is independent of the actual drive torque acting on the torque vectoring axis.

[0006] Another type of torque vectoring mechanism may be achieved by individual traction motors acting on the left and right wheels, again without relying on the actual drive torque acting on the torque vectoring axis.

[0007] Further variations on torque vectoring mechanisms depend on the available drive torque on the torque vectoring axes. One example, described further below, involves a propulsion unit, such as an electric motor, connected to the left wheel shaft by a first coupling and to the right wheel shaft by a second coupling. Through independent control of the couplings, the available drive torque provided by the propulsion unit is apportioned left / right according to the desired torque vectoring requirements.

[0008] Therefore, in the torque vectoring mechanism described above, a drive torque must be applied to the axle to allow the drive torque to be switched between the left and right wheels of the vehicle axle. However, if no drive torque is applied to the axle equipped with the torque vectoring mechanism, there is no torque to distribute to the left and right. Therefore, existing vehicles equipped with the torque vectoring mechanism described above, i.e., a mechanism in which the torque vectoring mechanism relies on the drive torque of the torque vectoring axle, may experience problems due to the fact that torque vectoring is only available during certain drive modes, such as AWD mode. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to solve the above-mentioned problems, and in particular to overcome the limitations of existing torque vectoring solutions for multi-axle drive vehicles.

[0010] The idea of ​​the present invention is to redistribute the net vehicle drive torque among the drive axles of the vehicle so that the drive torque levels at the axles equipped with torque vectoring meet the needs to perform the desired left-to-right torque vectoring. [Means for solving the problem]

[0011] According to a first aspect, a vehicle is provided, the vehicle comprising at least two drive shafts and at least one torque vectoring unit disposed on one of the drive shafts, thus forming a torque vectoring shaft. The vehicle further comprises a control unit configured to determine a specific torque corresponding to a desired torque vectoring requirement for the vehicle. If the absolute value of the drive torque supplied to the torque vectoring shaft is less than or not sufficient to achieve the determined specific torque, the control unit is further configured to: i) reallocate, or at least request a reallocation of, net vehicle drive torque among the drive shafts by increasing the drive torque of the torque vectoring shaft; and ii) distribute the increased drive torque of the torque vectoring shaft to the left and right wheels.

[0012] The torque vectoring unit is preferably configured to control the drive torque to each of the left and right wheels, and thus the torque vectoring unit is configured to actively control the lateral distribution of drive torque supplied to the torque vectoring shaft.

[0013] A vehicle may have a front drive axle, a rear drive axle, and optionally one or more intermediate axles. Thus, the present invention may be used in passenger cars, trucks, buses, construction equipment, etc.

[0014] The torque vectoring unit can be equipped with a right wheel clutch and a left wheel clutch, which can be controlled independently. The two clutches then act as a differential with built-in torque vectoring functionality, allowing for greater design freedom and making the torque vectoring shaft very compact.

[0015] If the drive torque supplied to the torque vectoring shaft is not sufficient to achieve the specific torque, the control unit is preferably configured to i) reallocate the net vehicle drive torque between said drive shafts so that at least the specific torque is distributed to the torque vectoring shaft, and ii) distribute the specific torque of the torque vectoring shaft to the left and right wheels.

[0016] According to a second aspect, there is provided a method for a vehicle, the vehicle comprising at least two drive shafts and at least one torque vectoring unit disposed on one of the drive shafts, thus forming a torque vectoring shaft. The method includes the steps of: i) determining a specific torque corresponding to a desired torque vectoring requirement for the vehicle; ii) determining a drive torque to be supplied to the torque vectoring shaft. If the determined absolute value of the drive torque of the torque vectoring shaft is not sufficient to achieve the specific torque, the method further includes the steps of: iii) reallocating net vehicle drive torque among the drive shafts by increasing the absolute value of the drive torque to the torque vectoring shaft, preferably such that at least the determined specific absolute value of torque is allocated to the torque vectoring shaft; and iv) allocating the increased drive torque, preferably by an amount corresponding to the specific torque of the torque vectoring shaft, to the left and right wheels.

[0017] In one embodiment, the step of reallocating the net vehicle drive torque among the drive shafts includes adding drive torque to the torque vectoring shaft and subtracting drive torque from the other drive shafts, so that the net vehicle drive torque remains unchanged, thereby enabling torque vectoring without affecting the longitudinal acceleration of the vehicle.

[0018] Reducing the drive torque from the other drive shaft can be done by reducing the drive torque, which is advantageous if a positive drive torque is already acting on the other drive shaft.

[0019] Reducing the drive torque from the other drive shaft can be done by applying a negative torque, which is particularly advantageous when the other drive shaft is an electric drive shaft.

[0020] Adding drive torque to a torque vectoring shaft can occur simultaneously with subtracting drive torque from other drive shafts, resulting in a smooth redistribution of net vehicle drive torque, thereby reducing undesirable vehicle behavior.

[0021] The step of redistributing the net vehicle drive torque between the drive axles can be performed simultaneously with distributing the torque vectoring axle specific torque to the left and right wheels, thereby further improving vehicle behavior during torque vectoring.

[0022] Reaching the desired absolute torque level on the torque vectoring axis can also be achieved by adding additional negative drive torque to the torque vectoring axis. This is advantageous when a negative drive torque already exists on the torque vectoring axis. In that situation, the drive torque of the other axis can be modified with a corresponding positive drive torque to achieve an unchanged net vehicle drive torque. [Brief explanation of the drawings]

[0023] In the following, reference is made to the accompanying drawings, in which:

[0024] [Figure 1] 1 is a schematic diagram of a vehicle according to one embodiment. [Figure 2] FIG. 1 is a schematic diagram of a torque vectoring axis of a vehicle according to one embodiment. [Figure 3]1 is a schematic diagram of a method according to one embodiment. [Figure 4] FIG. 1 illustrates torque distribution in a vehicle according to the prior art. [Figure 5] 10A-10C illustrate torque distributions in a vehicle according to different embodiments; [Figure 6] 10A-10C illustrate torque distributions in a vehicle according to different embodiments; [Figure 7] 7a and 7b are schematic diagrams of torque vectoring axes during different driving modes. [Figure 8] FIG. 2 illustrates torque distribution for a vehicle according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Starting with Figure 1, a vehicle 1 is shown diagrammatically. The vehicle 1 is a wheeled vehicle comprising a number of wheel axles 10, 20, 30. The front axle 10 is a drive axle, i.e. it is equipped with some kind of propulsion unit 12. In the example shown, the propulsion unit 12 may be, for example, an internal combustion engine or an electric motor. The propulsion unit 12 provides a drive torque to a differential 14, which in turn distributes the drive torque to the left and right front wheels 15a, 15b.

[0026] A rear axle 30, which is also a drive axle, is provided. Accordingly, the rear axle 30 has a propulsion unit 40 configured to provide drive torque to the rear axle 30. The propulsion unit 40, which will be further described with reference to FIG. 2, is configured to distribute drive torque to the left and right rear wheels 35 a, 35 b. In particular, in the illustrated example, the rear axle 30 is equipped with means for torque vectoring, i.e., the rear axle 30 is configured to actively redistribute drive torque between the left and right rear wheels 35 a, 35 b to improve drive performance, particularly with respect to yaw rate damping, traction performance, and improved vehicle stability. As explained in the Background section, the torque vectoring axle 30 is configured such that torque vectoring depends on the drive torque acting on the axle 30, which means that the torque vectoring unit is configured to actively control the lateral (i.e., left / right) distribution of drive torque.

[0027] As shown in FIG. 1 , one or more additional axles 20 may be provided. Each intermediate axle may be a drive axle or a non-drive axle. Furthermore, one or more of the intermediate axles 20 may be provided with torque vectoring functionality. Furthermore, it should be noted that the illustrated embodiment is provided merely as an example, and further alternative axle configurations are possible. For example, the front axle 10 may be provided with torque vectoring means, while the rear axle may or may not be provided with torque vectoring means.

[0028] The vehicle 1 further comprises a control unit 50 connected to the two drive shafts 10, 30, as will be further explained below.

[0029] The wheeled vehicle 1 may be a passenger car, which means that there is no intermediate axle 20. In other embodiments, the wheeled vehicle 1 may be a bus, a truck, construction equipment, or any other wheeled vehicle 1, as long as it has at least two drive axles 10, 30, at least one of which is a torque vectoring axle 30.

[0030] Referring now to FIG. 2, further details of the torque vectoring shaft 30 are shown. The propulsion unit 40 includes a propulsion motor 42, preferably an electric motor. The propulsion unit 40 further includes a torque differential, here in the form of two individually controllable clutches 44a, 44b. The propulsion motor 42 provides input torque to both clutches 44a, 44b, each of which has an output shaft connected to a respective left and right wheel 35a, 35b. In one example, the clutches 44a, 44b are hydraulically actuated disc clutches. When both clutches 44a, 44b are actuated with the same pressure, drive torque is distributed equally between the left and right wheels 35a, 35b. In extreme situations, one clutch 44a may be fully actuated while the other clutch 44b remains open, thereby distributing the entire positive or negative drive torque to only one wheel 35a.

[0031] A control unit 50 is connected to the propulsion motor 42 and each of the left and right clutches 44a, 44b and is programmed to control the operation of each of these components 42, 44a, 44b by transmitting corresponding control signals.

[0032] The control unit 50 is shown as a single component for simplicity. However, it should be understood that the control unit 50 may be designed in a variety of ways. For example, the control unit 50 may include a central processing unit (CPU), a computing module, and a memory device. The control unit 50 is provided with the connections described above and preferably provides certain communication modes for the control unit 50 to control torque vectoring, as described further below.

[0033] The control unit 50 is a microprocessor-based device that includes a CPU capable of processing input information related to torque vectoring, RAM and / or ROM serving as volatile memory units, along with associated input and output buses. The control unit 50 may be configured as an application-specific integrated circuit or through other logic devices known in the art. More specifically, the control unit 50 may form part of one or more of the vehicle's electronic control unit (ECU) modules, such as a torque vectoring ECU module and a propulsion ECU module, or alternatively may be configured as a standalone ECU. When the control unit 50 is implemented as a torque vectoring ECU module and a propulsion ECU module, the torque vectoring ECU module controls the clutches 44 a, 44 b, while the propulsion ECU module controls longitudinal torque distribution as requested by the torque vectoring ECU module, as described further below.

[0034] The control unit 50 outputs a control signal S DT1 to the traction motor corresponding to the requested drive torque. The control unit 50 is further configured to transmit a control signal S c1 , S c2 to the left and right clutches 44a, 44b corresponding to actuation levels indicative of the desired torque to be output from the respective clutches 44a, 44b. DT2 to the propulsion motors of the other drive shafts 10. To transmit these control signals, the control unit 50 receives an input signal S I Receive.

[0035] In the example shown, two clutches 44a, 44b together form a torque vectoring unit 45. The use of two independently controllable clutches 44a, 44b is advantageous in that it effectively decouples the traction motor 42 from the drivetrain when drive torque is not required for a particular drive shaft 30. However, other torque vectoring units 45 are contemplated in the context of the present invention, as are known in the art.

[0036] The vehicle is controlled according to the following general method 100, as shown generally in FIG. 3 . In a first step 102, torque vectoring of the drive axle 30 is requested. The method 100 then determines whether there is sufficient drive torque available to the torque vectoring axle 30. If there is not, in a second step 104, the vehicle's net vehicle drive torque is reallocated to increase the absolute drive torque of the torque vectoring axle 30 while decreasing the drive torque from the other drive axle 10 by an equal amount. Preferably, step 104 is performed so that the torque vectoring axle 30 has sufficient drive torque to achieve the requested torque vectoring. In step 106, which may be performed simultaneously with step 104, the drive torque of the torque vectoring axle 30 is reallocated between the left and right wheels 35 a, 35 b in accordance with the requested torque vectoring.

[0037] To further explain the present invention, reference is made to FIG. 4, which shows a diagram illustrating a prior art method for torque vectoring. x Between the torque vectoring shaft 30 and the other shaft 10, the torque vectoring shaft 30 is driven by a constant drive torque T1, while the other shaft 10 is driven by a constant drive torque T2. The net vehicle drive torque for the vehicle 1 is then T tot =T1+T2.

[0038] At time t1, torque vectoring is requested. The amount of torque vectoring requested, T TVis greater than the drive torque T1 of the torque vectoring shaft 30. According to what is known in the prior art, torque vectoring is only performed within the range of the drive torque T1 of the torque vectoring shaft 30. Therefore, torque vectoring is not performed at the required level.

[0039] An embodiment according to the present invention is shown in Figure 5. x between the torque vectoring shaft 30 and the other shaft 10, the vehicle 1 generates a total net vehicle drive torque T tot Initially, the driving torque T1 of the torque vectoring shaft 30 and the driving torque T2 of the other shaft 10 are constant.

[0040] At time t1, torque vectoring is requested. The amount of torque vectoring requested, T TV is greater than the initial drive torque T1 of the torque vectoring axis 30. When torque vectoring is initiated, the redistribution torque between the left and right wheels 35a, 35b reaches the current drive torque T1 of the torque vectoring axis 30 at time t2. To make more drive torque available for torque vectoring, the drive torque T1 of the torque vectoring axis 30 is preferably increased to reach the level required for the requested torque vectoring. At the same time, the same amount of drive torque is subtracted from the drive torque T2 of the other axis 10. The reverse procedure is performed when the requested torque vectoring is decreased, i.e., the increased drive torque T1 of the torque vectoring axis 30 is decreased to reach the initial drive torque T1 of the torque vectoring axis 30. At the same time, the same amount of drive torque is added to the drive torque T2 of the other axis 10. Therefore, the net vehicle drive torque T, corresponding to the sum of the drive torque T1 of the torque vectoring axis 30 and the drive torque T2 of the other axis 10, is tot remains constant during torque vectoring.

[0041] Another example of the torque vectoring procedure is shown in Figure 6. xbetween the torque vectoring shaft 30 and the other shaft 10, the vehicle 1 generates a total net vehicle drive torque T tot Initially, the drive torque T1 of the torque vectoring axis 30 is constant, while the drive torque T2 of the other axis 10 is zero.

[0042] At time t1, torque vectoring is requested. The amount of torque vectoring requested, T TV is greater than the initial drive torque T1 of the torque vectoring axis 30. When torque vectoring is initiated, the redistribution torque between the left and right wheels 35a, 35b reaches the current drive torque T1 of the torque vectoring axis 30 at time t2. To make more drive torque available for torque vectoring, the drive torque T1 of the torque vectoring axis 30 is increased to reach the level required for the requested torque vectoring. At the same time, the drive torque T2 of the other axis 10 is zero, so the same amount of drive torque is applied to the other axis 10 as negative torque. Preferably, in such an embodiment, the other axis 10 has an electric motor, so the negative torque can be regenerative torque. The reverse procedure is performed when the requested torque vectoring is decreased; i.e., the increased drive torque T1 of the torque vectoring axis 30 is decreased to reach the initial drive torque T1 of the torque vectoring axis 30. At the same time, the same amount of negative drive torque is removed from the other axis 10. Therefore, a net vehicle drive torque T corresponding to the sum of the drive torque T1 of the torque vectoring shaft 30 and the drive torque T2 of the other shaft 10 is generated. tot remains constant during torque vectoring.

[0043] A further example is shown with reference to Figures 7a-b and 8. Figure 7a shows a torque vectoring shaft 30. The torque vectoring shaft 30 is subjected to a drive torque T1 provided by a negative torque -T1 acting only on the left wheel 35a, i.e. the right clutch 44b is fully open.

[0044] In Figure 7b, the torque vectoring shaft 30 is subjected to the same absolute drive torque T1, but in this case, the drive torque T1 is supplied by a positive torque +T1 acting only on the right wheel 35b, i.e., the left clutch 44a is fully open. Therefore, in both cases shown in Figures 7a and 7b, the torque vectoring torque acting on the torque vectoring shaft is the same.

[0045] Figure 8 shows a diagram illustrating the torque vectoring procedure based on the driving conditions shown in Figure 7a. x between the torque vectoring shaft 30 and the other shaft 10, the vehicle 1 generates a total net vehicle drive torque T tot Initially, the drive torque T1 of the torque vectoring axis 30 is constant due to a negative torque −T1 applied to only the left wheel 35a, while the drive torque T2 of the other axis 10 is zero.

[0046] At time t1, torque vectoring is requested. The amount of torque vectoring requested, T TVis greater than the initial drive torque T1 of the torque vectoring axis 30. When torque vectoring is initiated, the redistribution torque between the left and right wheels 35a, 35b reaches the current drive torque T1 of the torque vectoring axis 30 at time t2. To make more drive torque available for torque vectoring, the drive torque T1 of the torque vectoring axis 30 is changed to reach the level required for the requested torque vectoring. This is accomplished by increasing the magnitude, or absolute value, of the negative torque -T1. At the same time, because the drive torque T2 of the other axis 10 is zero, the same amount of drive torque is applied to the other axis 10 as a positive torque. The reverse procedure is performed when the requested torque vectoring is decreased; i.e., the increased drive torque T1 of the torque vectoring axis 30 is decreased to reach the initial drive torque T1 of the torque vectoring axis 30. At the same time, the same amount of drive torque is removed from the other axis 10. Therefore, a net vehicle drive torque T corresponding to the sum of the drive torque T1 of the torque vectoring shaft 30 and the drive torque T2 of the other shaft 10 is generated. tot remains constant during torque vectoring.

[0047] It should be mentioned that the inventive concept is in no way limited to the embodiments described herein, but several modifications are possible without departing from the scope of the invention as defined in the appended claims.

Claims

1. A vehicle (1), at least two drive shafts (10, 30), and at least one torque vectoring unit (45) arranged on one of said drive shafts (30), thus forming a torque vectoring shaft; A specific torque (T) corresponding to a desired torque vectoring request for the vehicle (1) ＴＶ a control unit (50) configured to determine Equipped with The drive torque (T １ ) is the specific torque (T ＴＶ ), the control unit (50) further The torque vectoring shaft (30) １ redistributing the net vehicle drive torque between said drive shafts (10, 30) by increasing the absolute value of The increased drive torque (T １ ) to the left and right wheels (35a, 35b) The vehicle (1) is configured as follows.

2. 2. A vehicle according to claim 1, comprising a front drive axle (10), a rear drive axle (30), and optionally one or more intermediate axles (20).

3. The torque vectoring unit (45) distributes the drive torque (T １ 3. A vehicle as claimed in claim 1 or 2, configured to control the lateral distribution of

4. The vehicle of any one of claims 1 to 3, wherein the torque vectoring unit (45) comprises a left wheel clutch (44a) and a right wheel clutch (44b).

5. 5. The vehicle of claim 4, wherein the left wheel clutch (44a) and the right wheel clutch (44b) are independently controllable.

6. The drive torque (T １ ) is the specific torque (T ＴＶ ), the control unit (50) At least the specific torque (T ＴＶ redistributing the net vehicle drive torque between the drive shafts (10, 30) such that a torque vectoring shaft (30) is distributed to the torque vectoring shaft (30); The specific torque (T ＴＶ ) to the left and right wheels (35a, 35b). The vehicle according to any one of claims 1 to 5, wherein the vehicle is configured as follows.

7. 1. A method for a vehicle (1) comprising at least two drive shafts (10, 30) and at least one torque vectoring unit (45) arranged on one of said drive shafts (30), thus forming a torque vectoring shaft, said method comprising: A specific torque (T ＴＶ ) The drive torque (T １ ) and Including, The determined drive torque (T １ ) is the specific torque (T ＴＶ ), the method further comprising: The torque vectoring shaft (30) １ redistributing the net vehicle drive torque between said drive shafts (10, 30) by increasing the absolute value of The increased drive torque (T １ ) to the left and right wheels (35a, 35b); A method comprising:

8. 8. The method of claim 7, wherein redistributing the net vehicle drive torque between the drive shafts (10, 30) includes adding drive torque to the torque vectoring shaft (30) and subtracting drive torque from the other drive shafts (10).

9. 9. The method of claim 8, wherein reducing the drive torque from the other drive shaft (10) is performed by decreasing the drive torque.

10. 9. The method of claim 8, wherein the subtracting of the drive torque from the other drive shaft (10) is performed by applying a negative torque.

11. The method of any one of claims 8 to 10, wherein adding drive torque to the torque vectoring shaft (30) occurs simultaneously with subtracting drive torque from the other drive shafts (10).

12. 12. The method of claim 7, wherein the step of redistributing the net vehicle drive torque between the drive shafts (10, 30) is performed simultaneously with distributing the specific torque of the torque vectoring shaft (30) to the left and right wheels (35 a, 35 b).

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