Vehicle and control method for such vehicle
By redistributing net vehicle driving torque between the drive shafts of the vehicle, the problem that torque vector control depends on the driving torque in existing vehicles is solved, and torque vector control can be effectively performed in any driving mode, improving the stability and yaw rate damping of the vehicle.
Patent Information
- Application Number
- CN202380069291.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-10-03
- Filing Date
- 2023-10-03
- Publication Date
- 2025-05-16
AI Technical Summary
The torque vector control mechanism in existing vehicles depends on the drive torque, resulting in failure of torque vector control without the drive torque.
By redistributing the net vehicle driving torque between the drive shafts of the vehicle, the torque vector control shaft can meet the need to perform the desired left and right torque vector control, that is, by increasing the driving torque of the torque vector control shaft and subtracting the corresponding driving torque from the other drive shafts, the effectiveness of the torque vector control is ensured.
It realizes effective torque vector control in any driving mode, improves vehicle stability and yaw rate damping, and ensures continuous availability of torque vector control.
Smart Images
Figure CN120019222A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of wheeled vehicles and control methods thereof. In particular, the present invention relates to torque vector control in vehicles. Background Art
[0002] Wheeled vehicles can be multi-axle drive vehicles. One common type includes so-called all-wheel drive (AWD) vehicles. The main vehicle axle provides drive torque to the associated wheels of the axle, and when AWD is requested, the secondary axle is selectively controlled to also provide drive torque to its associated wheels. This feature can be achieved by mechanically connecting the secondary axle to the main axle so that the drive torque is distributed longitudinally. In a hybrid vehicle, the internal combustion engine can be in driving operation together with the front (main) axle, while the rear (secondary) axle can be driven by one or more electric motors. Such a vehicle can operate with front wheel drive (FWD), rear wheel drive (electric RWD) or AWD (FWD plus RWD).
[0003] More modern cars are purely electric, meaning one or more electric motors are provided to drive the front axle, rear axle, or both.
[0004] The vehicle may be equipped with torque vectoring, which is an effective technology for increasing yaw rate damping and improving vehicle stability during driving. Torque vectoring is generally applied to a single axle of the vehicle, whereby the drive torque to each of the corresponding left and right wheels can be controlled.
[0005] There are different types of mechanisms for providing torque vectoring. For example, a torque vectoring axle may be based on superposition, meaning that the differential distributes the drive torque equally, while the torque vectoring mechanism distributes the torque from one axle to the opposite axle. This type of torque vectoring mechanism does not depend on the actual drive torque acting on the torque vectoring axle.
[0006] Another type of torque vectoring mechanism can be implemented by separate propulsion motors acting on the left and right wheels, respectively. Also in this case, the torque vectoring mechanism does not depend on the actual drive torque acting on the torque vectoring shaft.
[0007] Another variation of a torque vectoring mechanism depends on the available drive torque on the torque vectoring axle. One embodiment, described further below, requires a propulsion unit, such as an electric motor, connected to the left axle by a first coupling and to the right axle by a second coupling. By controlling the couplings individually, the available drive torque provided by the propulsion unit is distributed left / right depending on the desired torque vectoring request.
[0008] Therefore, for the above-mentioned torque vectoring mechanism, there must be driving torque acting on the axle so that the driving torque can be dragged between the left and right wheels of the axle. However, when there is no driving torque acting on the axle provided with torque vectoring, there is no torque to distribute left and right. Therefore, existing vehicles with the above-mentioned torque vectoring mechanism, i.e., vehicles in which the torque vectoring mechanism depends on the driving torque of the torque vectoring axle, may suffer from the fact that torque vectoring is only available during a specific driving mode, such as AWD mode. Summary of 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 control schemes for multi-axle drive vehicles.
[0010] The concept of the present invention is to redistribute the net vehicle drive torque between the drive axles of the vehicle so that the drive torque level on the torque vectoring equipped axle meets the needs to perform the desired side-to-side torque vectoring.
[0011] According to a first aspect, a vehicle is provided. The vehicle comprises at least two drive shafts and at least one torque vectoring control unit, which is arranged on one drive shaft to form a torque vectoring control shaft. The vehicle further comprises a control unit, which is configured to determine a specific torque corresponding to a desired torque vectoring control demand of the vehicle. When the absolute value of the driving torque supplied to the torque vectoring control shaft is less than or insufficient to achieve the determined specific torque, the control unit is further configured to i) redistribute or at least request a redistribution of the net vehicle driving torque between the drive shafts by increasing the driving torque of the torque vectoring control shaft, and ii) distribute the increased driving torque of the torque vectoring control shaft to the left and right wheels.
[0012] The torque vectoring control unit is preferably configured to control the drive torque to each of the left and right wheels. Thus, the torque vectoring control unit is configured to actively control the lateral distribution of the drive torque supplied to the torque vectoring control axle.
[0013] The vehicle may include a front drive shaft, a rear drive shaft and optionally one or more intermediate shafts. Thus, the present invention may be used in passenger cars, trucks, buses, construction equipment, and the like.
[0014] The torque vectoring control unit may include a right wheel clutch and a left wheel clutch. The right wheel clutch and the left wheel clutch are independently controllable. The torque vectoring axle can be very compact with great design freedom because the two clutches will act as a differential with built-in torque vectoring function.
[0015] When the driving torque supplied to the torque vectoring control shaft is insufficient to achieve the specific torque, the control unit is preferably configured to i) redistribute the net vehicle driving torque between the driving shafts so that at least the specific torque is distributed to the torque vectoring control shaft, and ii) distribute the specific torque of the torque vectoring control shaft to the left and right wheels.
[0016] According to a second aspect, a method for a vehicle is provided. The vehicle comprises at least two drive shafts and at least one torque vectoring control unit, which is arranged on one drive shaft to form a torque vectoring control shaft. The method comprises i) determining a specific torque corresponding to a desired torque vectoring demand of the vehicle, ii) determining a driving torque supplied to the torque vectoring control shaft. When the determined absolute value of the driving torque of the torque vectoring control shaft is insufficient to achieve the specific torque, the method further comprises iii) redistributing the net vehicle driving torque between the drive shafts by increasing the absolute value of the driving torque of the torque vectoring control shaft, preferably so that at least the determined specific absolute value of the torque is distributed to the torque vectoring control shaft, and iv) distributing the increased driving torque to the left and right wheels, preferably to an amount corresponding to the specific torque of the torque vectoring control shaft.
[0017] In one embodiment, redistributing the net vehicle drive torque between the drive axles comprises adding drive torque to the torque vectoring axle and subtracting drive torque from the other drive axle. Thus, the net vehicle drive torque does not change, thereby allowing torque vectoring without affecting vehicle longitudinal acceleration.
[0018] Subtracting the drive torque from the other drive shaft can be performed by reducing the drive torque. This is advantageous if a positive drive torque already acts on the other drive shaft.
[0019] Subtracting the drive torque from the other drive shaft can be performed by applying a negative torque. This is particularly advantageous if the other drive shaft is an electric drive shaft.
[0020] Adding drive torque to a torque vectoring axle can be performed simultaneously with subtracting drive torque from another drive axle. In this way, there is a smooth redistribution of net vehicle drive torque, thereby reducing any undesirable vehicle behavior.
[0021] The redistribution of net vehicle drive torque between the drive axles can be performed simultaneously with the distribution of specific torque of the torque vectoring control axle to the left and right wheels. This further improves vehicle performance during torque vectoring.
[0022] Achieving the desired absolute torque level on the torque vectoring axle can also be achieved by adding more negative drive torque to the torque vectoring axle. This is advantageous if negative drive torque already exists on the torque vectoring axle. In this case, the other axle drive torques can be varied with the corresponding positive drive torques to achieve a constant net vehicle drive torque. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Reference will now be made to the accompanying drawings, in which:
[0024] Figure 1 is a schematic diagram of a vehicle according to one embodiment;
[0025] Figure 2 is a schematic diagram of a torque vectoring control axis of a vehicle according to one embodiment;
[0026] Figure 3 is a schematic diagram of a method according to one embodiment;
[0027] FIG4 is a diagram showing torque distribution of a vehicle according to the prior art;
[0028] Figure 5 and Figure 6 is a diagram showing torque distribution of a vehicle according to various embodiments;
[0029] Figure 7a and Figure 7b is a schematic diagram of the torque vectoring axles during different drive modes; and
[0030] Figure 8 is a diagram showing torque distribution of a vehicle according to an embodiment. DETAILED DESCRIPTION
[0031] from Figure 1 Initially, a vehicle 1 is schematically shown. The vehicle 1 is a wheeled vehicle comprising a plurality of wheel axles 10, 20, 30. The front axle 10 is a drive axle, i.e. it is provided with some kind of propulsion unit 12. In the embodiment 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 a left front wheel 15a and a right front wheel 15b.
[0032] A rear axle 30 is provided, which is also a drive axle. Therefore, the rear axle 30 has a propulsion unit 40, which is configured to provide a drive torque to the rear axle 30. Figure 2The propulsion unit 40 described further is configured to distribute the drive torque to the left rear wheel 35a and the right rear wheel 35b. In particular, in the embodiment shown, the rear axle 30 is provided with means for torque vectoring, i.e. it is configured to actively redistribute the drive torque between the left rear wheel 35a and the right rear wheel 35b in order to improve the driving performance, in particular with regard to yaw rate damping, traction performance and vehicle stability improvement. As explained in the background section, the torque vectoring control axle 30 is configured so that the torque vectoring depends on the drive torque acting on the axle 30, which means that the torque vectoring control unit is configured to actively control the lateral (i.e. left / right) distribution of the drive torque.
[0033] like Figure 1 As shown, one or more additional shafts 20 may be provided. Each intermediate shaft may be a driven shaft or a non-driven shaft. In addition, one or more intermediate shafts 20 may be provided with a torque vectoring function. It should also be noted that the illustrated embodiment is given as an example only; other alternatives to the axle configuration are possible, for example the front axle 10 may be provided with a torque vectoring device, while the rear axle may or may not be provided with a torque vectoring device.
[0034] The vehicle 1 further comprises a control unit 50 connected to the two drive axles 10 , 30 , as will be explained further below.
[0035] The wheeled vehicle 1 may be a passenger car, meaning that there is no intermediate shaft 20. In other embodiments, the wheeled vehicle 1 may be a bus, a truck, a 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.
[0036] Now go to Figure 2 , further details of the torque vectoring control shaft 30 are shown. The propulsion unit 40 includes a propulsion motor 42, preferably an electric motor. The propulsion unit 40 also includes a torque differential mechanism, here in the form of two individually controllable clutches 44a, 44b. The propulsion motor 42 provides input torque to the two clutches 44a, 44b, and each clutch 44a, 44b has an output shaft connected to the corresponding left wheel 35a and right wheel 35b. In one embodiment, the clutches 44a, 44b are hydraulically actuated disc clutches. If the two clutches 44a, 44b are actuated by the same pressure, the drive torque will be equally distributed between the left and right wheels 35a, 35b. In the extreme case, one clutch 44a is fully actuated while the other clutch 44b remains open, whereby the entire drive torque, positive or negative, is distributed to only one wheel 35a.
[0037] The control unit 50 is connected to the propulsion motor 42 and each of the left and right clutches 44a, 44b. The control unit 50 is programmed to control the operation of each of these components 42, 44a, 44b by sending corresponding control signals.
[0038] For simplicity, the control unit 50 is illustrated as a single component. However, it should be appreciated that the control unit 50 can be designed in various ways. For example, the control unit 50 includes a central processing unit (CPU), a computing module, and a storage device. The control unit 50 is provided with connections such as those described above, thereby providing a preferred constant communication mode for the control unit 50 to control torque vectoring control, as further described below.
[0039] The control unit 50 is a microprocessor-based device and includes a CPU capable of processing input information related to torque vectoring control, a RAM and / or ROM used as a volatile storage unit, and related input and output buses. The control unit 50 can be configured as a dedicated integrated circuit, or can be formed by other logic devices known in the art. More specifically, the control unit 50 can form a part of one or more of the electronic control unit (ECU) modules of the vehicle, such as a torque vectoring control ECU module and a propulsion ECU module, or can be configured as an independent ECU instead. In the case where the control unit 50 is implemented as a torque vectoring control ECU module and a propulsion ECU module, the torque vectoring control ECU module controls the clutches 44a, 44b, and the propulsion ECU module controls the longitudinal torque distribution according to a request from the torque vectoring control ECU module, which will be further described below.
[0040] The control unit 50 is configured to convert a control signal S corresponding to the requested driving torque into DT1 The control unit 50 is also configured to send the control signal S c1 , S c2 The control signal S is sent to the left and right clutches 44a, 44b, and corresponds to the actuation level representing the requested torque output from the corresponding clutch 44a, 44b. The control unit 50 is also configured to convert the control signal S DT2 to the propulsion motor of the other drive shaft 10. To transmit these control signals, the control unit 50 receives an input signal S representing a desired need for torque vectoring during driving. I .
[0041] In the embodiment shown, the two clutches 44a, 44b together form a torque vectoring control unit 45. The advantage of using two individually controllable clutches 44a, 44b is that they can effectively disconnect the propulsion motor 42 from the drive train if no drive torque is required for a particular drive shaft 30. However, in the context of the present invention, other torque vectoring control units 45 known in the art may be considered.
[0042] like Figure 3 As schematically shown, the vehicle is controlled according to the following general method 100. In a first step 102, torque vectoring of a drive axle 30 is requested. The method 100 then determines whether sufficient drive torque is available for the torque vectoring axle 30. If not, in a second step 104, the net drive torque of the vehicle is redistributed such that the absolute drive torque of the torque vectoring axle 30 is increased while also reducing the drive torque from the other drive axles 10 by the same amount. Preferably, step 104 is performed such 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 redistributed between the left wheel 35a and the right wheel 35b according to the requested torque vectoring.
[0043] To further explain the present invention, reference is made to FIG. 4 , which shows a diagram of a prior art method for torque vectoring control. x The torque vectoring control shaft 30 is driven by a constant driving torque T1, while the other shaft 10 is driven by a constant driving torque T2. The net vehicle driving torque of the vehicle 1 is then T tot =T1+T2.
[0044] At time t1, torque vectoring control is requested. The torque vectoring control demand T TV higher than the driving torque T1 of the torque vectoring shaft 30. According to what is known in the art, torque vectoring will be achieved, but only within the range of the driving torque T1 of the torque vectoring shaft 30. Therefore, torque vectoring is not performed at the required level.
[0045] Figure 5 shows an embodiment of the present invention, at time t0 and t x The vehicle 1 is driven by the total net vehicle torque T tot drive, the total net vehicle drive torque T tot This corresponds to the sum of the drive torque T1 of the torque vectoring control shaft 30 and the drive torque T2 of the other shaft 10. Initially, the drive torque T1 of the torque vectoring control shaft 30 and the drive torque T2 of the other shaft 10 are constant.
[0046] At time t1, torque vectoring control is requested. The torque vectoring control demand T TV Higher than the initial driving torque T1 of the torque vectoring control shaft 30. When the torque vectoring control starts, the torque redistributed between the left wheel 35a and the right wheel 35b will reach the current driving torque T1 of the torque vectoring control shaft 30 at time t2. In order to make more driving torque available for torque vectoring control, the driving torque T1 of the torque vectoring control shaft 30 is increased, preferably to the level required for the requested torque vectoring control. At the same time, the same amount of driving torque is subtracted from the driving torque T2 of the other shaft 10. When the requested torque vectoring control is reduced, that is, the increased driving torque T1 of the torque vectoring control shaft 30 is reduced to reach the initial driving torque T1 of the torque vectoring control shaft 30, the opposite process is performed. At the same time, the same amount of driving torque is added to the driving torque T2 of the other shaft 10. Therefore, the net vehicle driving torque T corresponding to the sum of the driving torque T1 of the torque vectoring control shaft 30 and the driving torque T2 of the other shaft 10 tot It remains constant during torque vectoring.
[0047] Another embodiment of the torque vectoring control process is Figure 6 At time t0 and t x The vehicle 1 is driven by the total net vehicle torque T tot Drive, total net vehicle drive torque T tot Corresponds to the sum of the drive torque T1 of the torque vectoring control shaft 30 and the drive torque T2 of the other shaft 10. Initially, the drive torque T1 of the torque vectoring control shaft 30 is constant, and the drive torque T2 of the other shaft 10 is zero.
[0048] At time t1, torque vectoring control is requested. The torque vectoring control demand T TVHigher than the initial driving torque T1 of the torque vectoring control shaft 30. When the torque vectoring control starts, the torque redistributed between the left wheel 35a and the right wheel 35b will reach the current driving torque T1 of the torque vectoring control shaft 30 at time t2. In order to make more driving torque available for torque vectoring control, the driving torque T1 of the torque vectoring control shaft 30 is increased to reach the level required for the requested torque vectoring control. At the same time, since the driving torque T2 of the other shaft 10 is zero, the same amount of driving torque is applied to the other shaft 10 as a negative torque. Preferably, for this embodiment, the other shaft 10 has an electric motor, whereby the negative torque can be a regenerative torque. When the requested torque vectoring control is reduced, that is, the increased driving torque T1 of the torque vectoring control shaft 30 is reduced to reach the initial driving torque T1 of the torque vectoring control shaft 30. At the same time, the same amount of negative driving torque is removed from the other shaft 10. Therefore, the net vehicle driving torque T corresponding to the sum of the driving torque T1 of the torque vectoring control shaft 30 and the driving torque T2 of the other shaft 10 is tot It remains constant during torque vectoring.
[0049] refer to Figure 7a-Figure 7b and Figure 8 Another embodiment is given. Figure 7a The torque vectoring shaft 30 is shown in . The torque vectoring shaft 30 is subjected to a driving torque T1 , which is provided by a negative torque −T1 acting only on the left wheel 35a , ie the right clutch 44b is fully open.
[0050] exist Figure 7b In the torque vectoring control, the shaft 30 is subjected to the same absolute drive torque T1, but in this case, the drive torque T1 is provided by the positive torque +T1 acting only on the right wheel 35b, i.e. the left clutch 44a is fully open. Figure 7a and Figure 7b In the two cases shown in , the torque vectoring torque acting on the torque vectoring axis is the same.
[0051] exist Figure 8 In the figure, it is shown that based on Figure 7a FIG. 1 is a diagram of the torque vectoring control process for the driving condition shown. At time t0 and t x The vehicle 1 is driven by the total net vehicle torque T tot drive, the total net vehicle drive torque T tot Corresponds to the sum of the drive torque T1 of the torque vectoring shaft 30 and the drive torque T2 of the other shaft 10. Initially, the drive torque T1 of the torque vectoring shaft 30 is constant by applying the negative torque -T1 only to the left wheel 35a, while the drive torque T2 of the other shaft 10 is zero.
[0052] At time t1, torque vectoring control is requested. The torque vectoring control demand T TV Higher than the initial drive torque T1 of the torque vectoring control shaft 30. When the torque vectoring control starts, the torque redistributed between the left wheel 35a and the right wheel 35b will reach the current drive torque T1 of the torque vectoring control shaft 30 at time t2. In order to make more drive torque available for torque vectoring control, the drive torque T1 of the torque vectoring control shaft 30 is changed to reach the required level for the requested torque vectoring control. This is achieved by increasing the magnitude or absolute value of the negative torque -T1. At the same time, since the drive torque T2 of the other shaft 10 is zero, the same amount of drive torque is applied to the other shaft 10 as a positive torque. When the requested torque vectoring control is reduced, that is, when the increased drive torque T1 of the torque vectoring control shaft 30 is reduced to reach the initial drive torque T1 of the torque vectoring control shaft 30, the opposite process is performed. At the same time, the same amount of drive torque is removed from the other shaft 10. Therefore, the net vehicle drive torque T corresponding to the sum of the drive torque T1 of the torque vectoring control shaft 30 and the drive torque T2 of the other shaft 10 tot It remains constant during torque vectoring.
[0053] It should be noted that the inventive concept is by no means limited to the embodiments described herein but that several modifications are possible without departing from the scope of the invention as defined in the appending claims.
Claims
1. A vehicle (1) comprising at least two drive shafts (10, 30) and at least one torque vectoring control unit (45), the torque vectoring control unit (45) being arranged on one of the drive shafts (30) to form a torque vectoring control shaft, and A control unit (50) configured to determine a specific torque (T TV );as well as When the driving torque (T1) supplied to the torque vectoring control shaft (30) is insufficient to achieve the specific torque (T TV ), the control unit (50) is further configured to: redistributing net vehicle drive torque between the drive axles (10, 30) by increasing the absolute value of the drive torque (T1) of the torque vectoring control axle (30), and The increased driving torque (T1) of the torque vector control shaft (30) is distributed to the left and right wheels (35a, 35b).
2. The vehicle according to claim 1, comprising a front drive shaft (10), a rear drive shaft (30) and optionally one or more intermediate shafts (20).
3. The vehicle according to claim 1 or 2, wherein: The torque vector control unit (45) is configured to control lateral distribution of the drive torque (T1) to each of the left and right wheels (35a, 35b).
4. A vehicle according to any one of the preceding claims, wherein: The torque vector control unit (45) includes a left wheel clutch (44a) and a right wheel clutch (44b).
5. The vehicle according to claim 4, wherein: The left wheel clutch (44a) and the right wheel clutch (44b) are independently controllable.
6. The vehicle according to any one of the preceding claims, wherein when the drive torque (T1) supplied to the torque vectoring control shaft (30) is insufficient to achieve the specific torque (T TV ), the control unit (50) is configured as follows: The net vehicle drive torque is redistributed between the drive shafts (10, 30) such that at least the specific torque (T TV ) is distributed to the torque vectoring control shaft (30), and The specific torque (T TV ) are distributed to the left and right wheels (35a, 35b).
7. A method for a vehicle (1), the vehicle comprising at least two drive shafts (10, 30) and at least one torque vectoring control unit (45), the torque vectoring control unit being arranged on one of the drive shafts (30) so as to form a torque vectoring control shaft, the method comprising: Determine a specific torque (T) corresponding to a desired torque vectoring demand of the vehicle TV ); determining a driving torque (T1) supplied to the torque vectoring control shaft (30); as well as When the determined driving torque (T1) of the torque vector control shaft (30) is insufficient to achieve the specific torque (T TV ), the method further comprises: redistributing net vehicle drive torque between the drive axles (10, 30) by increasing the absolute value of the drive torque (T1) of the torque vectoring control axle (30), and The increased driving torque (T1) of the torque vector control shaft (30) is distributed to the left and right wheels (35a, 35b).
8. The method according to claim 7, wherein: Redistributing the net vehicle drive torque between the drive axles (10, 30) includes adding drive torque to the torque vectoring control axle (30) and subtracting drive torque from the other drive axle (10).
9. The method according to claim 8, wherein: Subtracting the driving torque from the other driving shaft (10) is performed by reducing the driving torque.
10. The method according to claim 8, wherein: Subtracting the driving torque from the further driving shaft (10) is performed by applying a negative torque.
11. The method according to any one of claims 8 to 10, wherein: Adding the driving torque to the torque vectoring control shaft (30) is performed simultaneously with subtracting the driving torque from the other driving shaft (10).
12. The method according to any one of claims 7 to 11, wherein: While distributing the specific torque of the torque vectoring control shaft (30) to the left and right wheels (35a, 35b), redistribution of the net vehicle driving torque between the drive shafts (10, 30) is performed.