Torque vectoring device and vehicle traveling control system

Abstract

To provide a torque vectoring device which is small in number of part items and high in reliability.SOLUTION: A torque vectoring device 501 controls the distribution of the rotation number and torque with respect to right and left wheels constituting driving wheels or driven wheels of a vehicle. A planetary reduction gear 30 includes three shafts such as a sun shaft 35 being a shaft of a sun gear 31, a carrier shaft 36 being a shaft of a planetary carrier 32, and a ring shaft 37 being a shaft of a ring gear 33. A right-left torque distribution motor 55 is connected to one motor shaft (for example, the sun shaft 35) which is selected from the three shafts of the planetary reduction gear 30, and adjusts rotation numbers of the two shafts (for example, the carrier shaft 36 and the ring shaft 37) other than the motor shaft by changing the rotation number of the motor shaft. A first wheel transmission mechanism 410 and a second wheel transmission mechanism 420 connect the two shafts other than the motor shaft of the planetary reduction gear and wheel shafts of right and left wheels, respectively. A distribution motor control part 57 controls the drive of a right-left torque distribution motor 55 on the basis of a requirement of a vehicle motion which is indicated from the outside.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a torque vectoring device and a vehicle cruise control system. [Background technology]

[0002] 2. Description of the Related Art Torque vectoring devices that adjust the distribution of driving force transmitted to left and right wheels of a vehicle are known.

[0003] For example, the torque transmission device disclosed in Patent Document 1 is provided with a pair of yaw control devices as mechanisms for applying load torque to the torque transmitted from the differential to the left and right wheels, respectively. The yaw control devices include a planetary gear mechanism, a multi-plate clutch, an electric motor, etc. The yaw control devices limit the rotation of the wheel axles by controlling the engagement of the multi-plate clutch. The yaw control devices also control the electric motor (actuator) to accelerate the left and right wheels, and generate a yaw moment in the vehicle to control the turning behavior. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-215584 A Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional technology of Patent Document 1 uses two yaw control devices, each including a planetary gear mechanism and an actuator, which increases the number of parts. In addition, the frictional force of a multi-plate clutch is used to brake the wheel axle, which raises concerns about reduced reliability.

[0006] The present invention has been created in consideration of the above-mentioned points, and its object is to provide a torque vectoring device that has a small number of mechanisms and actuator parts and is highly reliable, and a vehicle driving control system including the same. [Means for solving the problem]

[0007] The torque vectoring device of the present invention controls the rotation speed and distribution of torque to a pair of left and right wheels constituting drive wheels or driven wheels of a vehicle (901-903). The torque vectoring device includes a planetary reduction gear (30), a left and right torque distribution motor (55), a first wheel transmission mechanism (410), a second wheel transmission mechanism (420), and a distribution motor control unit (57).

[0008] The planetary reduction gear includes three shafts: a sun shaft (35) which is the shaft of the sun gear (31), a carrier shaft (36) which is the shaft of the planetary carrier (32), and a ring shaft (37) which is the shaft of the ring gear (33). The left and right torque distribution motor is connected directly or via a reducer to a motor shaft selected from among the three shafts of the planetary reduction gear, and adjusts the rotation speeds of the two shafts other than the motor shaft by changing the rotation speed of the motor shaft.

[0009] The first wheel transmission mechanism and the second wheel transmission mechanism connect one and the other of the two shafts other than the motor shaft of the planetary reduction gear to one and the other of the left and right wheel shafts, respectively. The distribution motor control unit controls the drive of the left and right torque distribution motors based on a vehicle operation request instructed from the outside.

[0010] In the present invention, the rotation speed and torque distribution of the left and right wheels can be controlled with a simple configuration using a set of mechanisms and actuators for a pair of left and right wheels, i.e., a planetary reduction gear and a left and right torque distribution motor. Therefore, the number of parts is reduced compared to the conventional technology of Patent Document 1. In addition, reliability is improved because there is no braking element such as a friction clutch.

[0011] A vehicle driving control system according to one aspect of the present invention is applied to a vehicle (901-903) having one or more pairs of drive wheels among multiple pairs of left and right wheels. The vehicle driving control system includes one or more axle power sources (15), one or more differentials (20) that transmit torque generated by the axle power sources to the drive wheels, an axle power source control unit (17) that controls the rotation of the axle power sources, and one or more torque vectoring devices (500D) provided corresponding to the drive wheels. The vehicle driving control system controls the straight-line or turning movement of the vehicle by distributing the rotation speed and torque of the left and right wheels by the torque vectoring device.

[0012] In the vehicle driving control system of the present invention, by using the torque vectoring device described above, it is possible to appropriately control the rotation speed and torque distribution of the left and right drive wheels with a simple and highly reliable configuration. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram of a vehicle configuration example 1 (2WD) to which a torque vectoring device is applied. [Diagram 2] FIG. 1 is a diagram of a vehicle configuration example 2 (4WD) to which a torque vectoring device is applied. [Diagram 3] FIG. 1 is a block diagram of a vehicle driving control system using a torque vectoring device for driving wheels. [Figure 4] FIG. 1 is a block diagram of a vehicle driving control system using a torque vectoring device for driven wheels. [Diagram 5] FIG. 1 is a configuration diagram of a torque vectoring device according to a first embodiment. [Figure 6] Schematic diagram of a 2KH type planetary reducer. [Figure 7] This is a nomogram of a planetary reducer that explains the speed ratio between the carrier shaft rotation speed ωp and the ring shaft rotation speed ωc when the sun shaft rotation speed ωa = 0 (upper part) and when ωa > 0 (lower part). [Figure 8] 6 is a collinear diagram showing the case where ωTL=ωTR when ωa=0 in the basic example of the first embodiment. [Figure 9]13 is a collinear diagram showing a case where ωTL=ωTR when ωa>0 in the modified example of the first embodiment. [Figure 10] FIG. 11 is a collinear diagram when ωmg=0 and ωTL<ωTR in the basic example of the first embodiment. [Figure 11] A diagram showing the pivot turning operation of (a) a 4WD and (b) an AGV using a torque vectoring device. [Figure 12] 3 is a diagram illustrating an energy balance of a vehicle driving control system including a torque vectoring device. [Figure 13] FIG. 11 is a configuration diagram of a torque vectoring device according to a second embodiment. [Figure 14] FIG. 7 is a collinear diagram of the torque vectoring device according to the second embodiment. [Figure 15] FIG. 13 is a configuration diagram of a torque vectoring device according to a third embodiment. [Figure 16] FIG. 11 is a collinear diagram of the torque vectoring device according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A number of embodiments of the torque vectoring device will be described with reference to the drawings. The following first to third embodiments are collectively referred to as "the present embodiment." The torque vectoring device of the present embodiment controls the rotation speed and torque distribution to a pair of left and right wheels that constitute the driving wheels or driven wheels of a vehicle. A vehicle driving control system includes one or more torque vectoring devices, and controls the straight-line or turning movement of the vehicle by distributing the rotation speed and torque to the left and right wheels by each torque vectoring device.

[0015] 1 and 2, a configuration example of a vehicle to which a torque vectoring device 500 of this embodiment is applied is shown. The reference numeral "500" is a reference numeral that collectively includes the torque vectoring devices of the first to third embodiments regardless of differences in internal structure. Vehicles 901 and 902 shown in Figs. 1 and 2 are four-wheel vehicles equipped with two pairs of left and right wheels 91-94 at the front and rear. Each wheel 91-94 rotates by torque transmitted from the corresponding wheel axle 81-84. An AGV 903 will be described later as an example of another vehicle.

[0016] The vehicle 901 shown in Fig. 1 is a front-wheel drive 2WD vehicle in which left and right front wheels 91, 92 are drive wheels and left and right rear wheels 93, 94 are driven wheels. For example, in an electric vehicle, the axle motor 15 as an "axle power source" is typically composed of a main engine MG. Torque is transmitted from the axle motor 15 to the left and right front wheels 91, 92 via a differential 20 and wheel axles 81, 82. An axle motor control unit 17 controls the rotation of the axle motor 15. A reducer 19 is provided between the axle motor 15 and the differential 20.

[0017] In addition, in engine vehicles and hybrid vehicles, the engine may be used as the "axle power source." In addition, in this specification, the vehicle configuration in Fig. 1, which is "front MG, front drive," will be referred to as "FF" in accordance with "front engine, front drive."

[0018] A vehicle 902 shown in Fig. 2 is a 4WD in which both left and right front wheels 91, 92 and left and right rear wheels 93, 94 are driven wheels. For example, an electric vehicle is equipped with two axle motors 15, a front wheel main engine MG and a rear wheel main engine MG, as "axle power sources". Torque is transmitted from the front wheel axle motor 15 to the left and right front wheels 91, 92 via the front wheel differential 20 and wheel axles 81, 82. Similarly, torque is transmitted from the rear wheel axle motor 15 to the left and right rear wheels 93, 94 via the rear wheel differential 20 and wheel axles 83, 84.

[0019] In the example of Fig. 1, the torque vectoring device 500 is provided for the front wheels 91, 92 which are driving wheels, and for the front wheels 93, 94 which are driven wheels. For the purpose of distinction, the torque vectoring device for driving wheels provided corresponding to the driving wheels 91, 92 is given a sub-reference symbol in parentheses (500D), and the torque vectoring device for driven wheels provided corresponding to the driven wheels 93, 94 is given a sub-reference symbol in parentheses (500N). These sub-reference symbols are used only in Figs. 1 to 4.

[0020] The torque vectoring device 500 includes a planetary reduction gear 30, a left / right torque distribution motor 55, a left wheel transmission mechanism 410, a right wheel transmission mechanism 420, and a distribution motor control unit 57. In Figures 1 and 2, the "left / right torque distribution motor" is abbreviated to "distribution motor".

[0021] As described below, the planetary reduction gear 30 includes three shafts: a sun shaft, a carrier shaft, and a ring shaft. One of the three shafts is selected as the motor shaft. The first to third embodiments select different motor shafts. The left and right torque distribution motor 55 is connected to the motor shaft of the planetary reduction gear 30, and adjusts the rotation speed of the two shafts other than the motor shaft by changing the rotation speed of the motor shaft.

[0022] The left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 correspond to the “first wheel transmission mechanism” and the “second wheel transmission mechanism.” The left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 connect one and the other of the two shafts other than the motor shaft of the planetary reduction gear 30 to one and the other of the left and right wheel axles 81-84, respectively.

[0023] In the drive wheel torque vectoring device 500D, the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 are connected to the differential 20 via the wheel axles 81-84. The torque generated by the axle motor 15 is transmitted to the planetary reduction gear 30 via the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420.

[0024] On the other hand, in the torque vectoring device for driven wheels 500N, the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 are not connected to the differential 20. In the FF vehicle of Fig. 1, the drive wheels 91, 92 are rotated by the torque of the front wheel axle motor 15, and the vehicle 901 runs, thereby rotating the driven wheels 93, 94. The rotation of the driven wheels 93, 94 is then transmitted from the wheel shafts 83, 84 to the planetary reduction gear 30 via the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420.

[0025] The distribution motor control unit 57 controls the driving of the left and right torque distribution motors 55 based on an externally instructed request for vehicle operation. The request for vehicle operation will be described later with reference to Figs. 3 and 4.

[0026] In the example of Fig. 1, the vehicle driving control system is applied to a 2WD 901 having a pair of driving wheels 91, 92 and a pair of driven wheels 93, 94 among multiple pairs of left and right wheels. The vehicle driving control system includes an axle motor 15, a differential 20, an axle motor control unit 17, a torque vectoring device 500D for driving wheels, and a torque vectoring device 500N for driven wheels. The differential 20 transmits the torque generated by the axle motor 15 to the driving wheels 91, 92.

[0027] 2, the vehicle driving control system is applied to a 4WD 902 having two pairs of drive wheels 91, 94 among multiple pairs of left and right wheels. The vehicle driving control system includes two axle motors 15, two differentials 20, an axle motor control unit 17, and two drive wheel torque vectoring devices 500D. Each differential 20 transmits the torque generated by each axle motor 15 to the drive wheels 91, 92 and drive wheels 93, 94.

[0028] 3 and 4 show the control configurations of a vehicle driving control system including a torque vectoring device for driving wheels 500D and a torque vectoring device for driven wheels 500N, respectively. Here, we focus on matters related to rotation speed control, and omit controls other than rotation speed. The symbol ω is used as the symbol for rotation speed as well as the symbol for rotation speed, which is the converted value of speed. In the following explanations of the alignment charts, etc., "rotation speed" and "speed" are used synonymously.

[0029] First, matters common to Fig. 3 and Fig. 4 will be described. A reducer 59 may be provided between the left / right torque distribution motor 55 and the motor shaft of the planetary reduction gear 30, as indicated by the dashed line. This reduces the speed and increases the torque of the left / right torque distribution motor 55 before transmitting it to the motor shaft. This makes it possible to reduce the size of the motor required to output the desired torque. The reducer 59 is not shown in Fig. 5 and subsequent diagrams.

[0030] As indicated by the dashed line, the left / right torque distribution motor 55 is connected to the auxiliary battery 63 via, for example, an inverter 64. During power running, energy from the auxiliary battery 63 is supplied to the left / right torque distribution motor 55. On the other hand, when the motor shaft rotation speed is not 0 on the collinear diagram, if torque is reversely input from the wheel shaft to the two shafts other than the motor shaft, the left / right torque distribution motor 55 may rotate due to regenerative operation. In this case, energy generated by the regenerative operation of the left / right torque distribution motor 55 is regenerated to the auxiliary battery 63 via the inverter 64.

[0031] As a "request for vehicle operation", a driver's operation signal for the steering wheel, accelerator, or brake, or an equivalent signal in an automatic driving mode, is input to the vehicle ECU 70. The vehicle ECU 70 outputs a braking / driving command based on the input signal to the axle motor control unit 17. The axle motor control unit 17 outputs a rotation speed command value ωmg to the axle motor 15. * The vehicle ECU 70 also outputs a yaw command to the steering device and distribution motor control unit 57, indicating to the left or right how much the vehicle is trying to turn.

[0032] The distribution motor control unit 57 estimates the average rotation speed of the left and right wheels based on the braking / driving command or the actual vehicle speed, and calculates the rotation speed difference between the left and right wheels based on the yaw command. The distribution motor control unit 57 calculates the rotation speed command value ωmd of the left and right torque distribution motor 55 from the alignment chart of the planetary reduction gear 30 described later. * and outputs it to the left and right torque distribution motor 55. The distribution motor control unit 57 is omitted from the configuration diagrams of FIG.

[0033] The torque vectoring device 500D for driving wheels shown in Fig. 3 can be controlled in combination with the corresponding axle motor 15. The distribution motor control unit 57 receives the rotation speed command value ωmg of the axle motor 15 from the axle motor control unit 17. * (dashed arrow), or the rotation speed detection value ωmg_sns detected by the rotation sensor 16 or its correlation value is acquired (solid arrow). With this configuration, braking / driving of the drive wheels by the axle motor 15 and distribution of the rotation speed and torque by the left / right torque distribution motor 55 can be performed simultaneously.

[0034] In the torque vectoring device 500N for driven wheels shown in Fig. 4, the distribution motor control unit 57 estimates the average rotation speed of the driven wheels 93, 94 from the rotation speed of the axle motor 15 on the driving wheel side 91, 92 and the vehicle speed. * Alternatively, the rotational speed detection value ωmg_sns may be acquired, or the vehicle speed V may be acquired from the vehicle speed sensor 76.

[0035] Next, a specific configuration of the torque vectoring device 500 will be described for each embodiment. While the torque vectoring device is generically designated by the symbol "500" in Fig. 1 to Fig. 4, in the first to third embodiments, the third digit following the "50" in the symbol for the torque vectoring device is used to designate the embodiment. The torque vectoring devices 501 to 503 in the first to third embodiments differ in which of the three shafts of the planetary reduction gear 30 is selected as the "motor shaft" to which the left and right torque distribution motors 55 are connected.

[0036] For each embodiment, the configuration of the torque vectoring devices 501-503 is shown by a configuration diagram, and the speed ratio of the three shafts of the planetary reduction gear 30 is shown by a collinear diagram. The configuration diagram illustrates the configuration of a torque vectoring device for driving wheels 500D applied to the left and right front wheels 91, 92 of the vehicles 901, 902 in Figs. 1 and 2. The wheel axles 81, 82 of the left and right wheels 91, 92 are connected to a differential 20. The torque generated by the axle motor 15 is transmitted to the left and right wheels 91, 92 via the reducer 19 and the differential 20. The rotation speed ωdf, which is the rotation speed ωmg of the axle motor 15 reduced by the reducer 19, is input to the differential 20.

[0037] A 2KH type planetary gear mechanism is shown as a representative example of the planetary reduction gear 30. However, a 3K type or KHV type planetary gear mechanism or a compound planetary gear mechanism may be used other than the 2KH type. Also, as described above, a reducer 39 may be provided between the left and right torque distribution motor 55 and the motor shaft of the planetary reduction gear 30. In other words, the left and right torque distribution motor 55 is connected to the motor shaft directly or via a reducer.

[0038] (First embodiment) The configuration of a torque vectoring device 501 of the first embodiment will be described with reference to Figs. 5 to 9. As shown in Figs. 5 and 6, the planetary gear mechanism of the planetary reduction gear 30 is made up of a sun gear 31, a planetary carrier 32 that receives the revolutions of the pinion gears 34, and a ring gear 33. The shaft of the sun gear 31 is represented as a sun shaft 35, the shaft of the planetary carrier 32 as a carrier shaft 36, and the shaft of the ring gear 33 as a ring shaft 37. The planetary reduction gear 30 includes three shafts: the sun shaft 35, the carrier shaft 36, and the ring shaft 37.

[0039] One of these three shafts is selected as the motor shaft. In the torque vectoring device 501 of the first embodiment, the motor shaft is the sun shaft 35. That is, a left / right torque distribution motor 55 is connected to the sun shaft 35. As will be described later with reference to the alignment charts of FIGS. 7 to 9, the left / right torque distribution motor 55 adjusts the rotation speeds of the two shafts other than the motor shaft by changing the rotation speed of the motor shaft.

[0040] In the first embodiment, the two shafts other than the motor shaft are the carrier shaft 36 and the ring shaft 37. The left wheel transmission mechanism 410 is composed of a carrier shaft transmission gear 46 connected to the carrier shaft 36 and a left wheel shaft gear 41. The right wheel transmission mechanism 420 is composed of a ring shaft transmission gear 47 connected to the ring shaft 37 and a right wheel shaft gear 42. The left wheel shaft gear 41 and the right wheel shaft gear 42 are connected to wheels 81 and 82 of a left wheel 91 and a right wheel 92, respectively. In addition, each wheel 81 and 82 is connected to the differential 20. The left wheel 91 may be read as "tire L" and the right wheel 92 as "tire R". In the symbols ωTL and ωTR for the rotation speeds of the left and right wheels, "T" comes from tire.

[0041] A typical 2KH type planetary gear mechanism is shown in Figure 6. The numbers of teeth of the sun gear 31, pinion gear 34, and ring gear 33 are designated by symbols Za, Zp, and Zc. The rotation speeds of the sun shaft 35, carrier shaft 36, and ring shaft 37 are designated by symbols ωa, ωp, and ωc, which are also shown in Figure 5. In Figure 5, the rotation speeds of the wheel shafts 81 and 82 of the left wheel 91 and right wheel 92 are designated by symbols ωTL and ωTR, respectively. The subscripts of the symbols are written as subscripts in the figures, and in normal letters in the specification.

[0042] The upper part of Figure 7 shows a collinear diagram when the sun shaft rotation speed ωa is 0 (ωa = 0). The relationship between the ring shaft rotation speed ωc and the carrier shaft rotation speed ωp is expressed by formula (1a). Since (Za / Zc)>0, ωc>ωp.

[0043] ωc=ωp×{(Za / Zc)+1} ···(1a)

[0044] The lower part of Figure 7 shows a collinear diagram when the sun shaft rotation speed ωa is positive (ωa>0). The relationship between the ring shaft rotation speed ωc and the carrier shaft rotation speed ωp is expressed by equation (1b). When ωp>ωa, (Za / Zc)>0, so ωc>ωp.

[0045] ωc=ωp+(ωp-ωa)×(Za / Zc) ···(1b)

[0046] 8, the relationship between the carrier shaft rotation speed ωp and the ring shaft rotation speed ωc in the planetary reduction gear 30 and the rotation speeds ωTL and ωTR of the left and right wheel axles 81, 82 will be considered. The reduction ratio XL of the left wheel transmission mechanism 410 and the reduction ratio XR of the right wheel transmission mechanism 420 are defined by equations (2.1) and (2.2).

[0047] XL = ωp / ωTL (2.1) XR = ωc / ωTR (2.2)

[0048] In the basic example of the first embodiment shown in the alignment chart in FIG. 8, the torque vectoring device 501 is configured so that the rotation speeds ωTL and ωTR of the left and right wheels are equal when the motor shaft is stationary, that is, when the sun shaft rotation speed ωa is 0. In the alignment chart of the planetary reduction gear 30, the solid speed line is the same as that in the upper part of FIG. 7. At this time, it is required that "ωTL = ωTR" is satisfied in the alignment chart of the differential 20. The condition of the reduction ratios XL and XR for this relationship to be satisfied is determined by equation (3) using equation (1a) by assuming that "ωTL = ωTR" in equations (2.1) and (2.2).

[0049] XR=(ωc / ωp)×XL={(Za / Zc)+1}×XL ···(3)

[0050] The gear ratios of the gears 41, 42, 46, 47 of the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 are determined based on the formula (3). This makes it possible to set the drive energy of the left and right torque distribution motor 55 to zero when the vehicle is traveling straight, thereby preventing the occurrence of unnecessary losses. This is particularly advantageous when the proportion of straight travel is high, such as when traveling long distances.

[0051] In the configuration set up in this way, the dashed speed line in Fig. 8 shows the behavior when the left and right wheels are made to have different rotation speeds when turning the vehicle. In this example, it is assumed that the right wheel rotation speed ωTR is made larger than the left wheel rotation speed ωTL when turning left (ωTL<ωTR). In the collinear diagram of the differential 20, the slope of the speed line changes with the average rotation speed ωTM between the left wheel rotation speed ωTL and the right wheel rotation speed ωTR as the fulcrum. Here, the average rotation speed ωTM is determined based on the rotation speed ωmg of the axle motor 15.

[0052] If the converted value corresponding to the average rotation speed ωTM in the collinear diagram of the planetary reduction gear 30 is the converted average rotation speed ωVM, the gradient of the velocity line changes with the converted average rotation speed ωVM as the fulcrum. In other words, the rotation speeds ωa, ωp, and ωc of the three shafts of the planetary reduction gear 30 change with the converted average rotation speed ωVM as the reference.

[0053] FIG. 9 shows a collinear diagram of a modified example of the first embodiment different from the basic example shown in FIG. 8. In the modified example of FIG. 9, the left and right wheels are configured to have the same rotation speeds ωTL and ωTR when the motor shaft rotates. In other words, the left and right torque distribution motor 55 rotates when the vehicle moves straight. In the collinear diagram of the planetary reduction gear 30, the solid speed line is the same as that in the lower part of FIG. 7. At this time, the condition of the reduction ratios XL and XR for "ωTL = ωTR" in the collinear diagram of the differential 20 is obtained using the formula (1b) as described above, and the gear ratios of the gears 41, 42, 46, and 47 of the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 are determined based on the result.

[0054] In the configuration thus set, the dashed speed line in FIG. 9 shows the behavior when the left and right wheels are made to have different rotation speeds when the vehicle turns. In this example, it is assumed that the right wheel rotation speed ωTR is made larger than the left wheel rotation speed ωTL when turning left (ωTL<ωTR). When the sun shaft rotation speed ωa is 0 and the difference in rotation speed between the left and right wheels (ωTR-ωTL) is a predetermined value, the vehicle turns left with a predetermined turning radius according to the vehicle speed and the road surface friction coefficient. Therefore, when traveling counterclockwise around a circular course of a predetermined radius for a specific purpose, the driving energy of the left and right torque distribution motors 55 can be made 0, and unnecessary losses can be avoided.

[0055] In this way, it is preferable to set the collinear diagram of the planetary reduction gear 30 depending on whether the main driving pattern of the vehicle to which it is applied is straight-line driving or turning driving with the same radius and direction. Also, a speed-changing gear structure may be provided in the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 so that the transmission gears can be switched depending on the driving scene.

[0056] In addition, the structural advantages of the torque vectoring device 501 of the first embodiment will be described in comparison with the second and third embodiments described later. In the first embodiment, the left and right torque distribution motor 55 is connected to the sun shaft 35, so that the structure can be simplified. In addition, the distance on the collinear diagram between the carrier shaft 36 and the ring shaft 37 connected to the left and right wheels is relatively small, and the difference in the rotation speeds ωp, ωc of the two shafts is relatively small. Therefore, the difference between the reduction ratios XL, XR of the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 can be set relatively small, increasing the degree of freedom in design.

[0057] (Application: pivot turn) Next, with reference to Fig. 10, Fig. 11(a) and Fig. 11(b), a pivot turn will be described as an applied operation of a vehicle using this embodiment. Although an example of the first embodiment will be described, similar operations are possible in the second and third embodiments. Fig. 10 shows a collinear diagram when the rotation speed ωmg of the axle motor 15 is 0 in comparison with Fig. 8. As shown by the solid line, when the rotation speeds of the left and right wheels are equal (ωTL = ωTR = 0), the sun shaft rotation speed ωa is 0, so the rotation speeds of the three shafts of the planetary reduction gear 30 are all 0 (ωa = 0, ωp = 0, ωc = 0), and the vehicle is stopped.

[0058] As shown by the dashed line, when the sun shaft rotation speed ωa is made negative, the carrier shaft rotation speed ωp becomes negative and the ring shaft rotation speed ωc becomes positive. As a result, the left wheel rotation speed ωTL becomes negative and the right wheel rotation speed ωTR becomes positive, and the left and right wheels rotate in opposite directions.

[0059] As shown in Fig. 11(a), for example, when right wheels 92, 94 of both the front and rear wheels of a 4WD 902 are rotated forward and left wheels 91, 93 are rotated backward, the vehicle 902 makes a pivot turn to the left about the center of gravity. The conventional technology of Patent Document 1 applies a braking difference between the left and right wheels when the left and right wheels turn in the same direction, and it is not possible to rotate the left and right wheels in opposite directions. In contrast, in this embodiment, it is possible to actively control the rotation of the left and right wheels in opposite directions.

[0060] FIG. 11(b) shows an AGV 903 used for unmanned transport in factories as another example of a vehicle. The AGV 903 has a pair of drive wheels 91, 92 on both the left and right sides of the center of gravity, and a number of driven wheels 95-98 in front of and behind the center of gravity. The driven wheels 95-98 may be formed of casters that can rotate freely in all directions. When the right wheel 92 of the drive wheels is rotated forward and the left wheel 91 is rotated backward, the AGV 903 pivots to the left about the center of gravity. In terms of the operating characteristics of the AGV 903, it is effective to be able to freely change direction in a narrow space.

[0061] With reference to Fig. 12, the energy balance in a vehicle driving control system to which torque vectoring device 500 is applied will be described. The horizontal axis represents the torque difference between the left and right wheels, which is 0 when the vehicle is moving straight ahead. When the torque difference between the left and right wheels is positive, it is represented that a positive yaw moment is occurring, and when the torque difference between the left and right wheels is negative, it is represented that a negative yaw moment is occurring. The vertical axis represents driving energy.

[0062] The output (i.e., rotation speed and torque) of the axle motor 15 is constant. The rotation speed of the left and right torque distribution motor 55 and the difference in rotation speed between the left and right wheels are also constant. When a positive yaw moment occurs, the output of the left and right torque distribution motor 55 acts in the driving direction of the vehicle and is added to the output of the axle motor 15. When a negative yaw moment occurs, the output of the left and right torque distribution motor 55 acts in the braking direction of the vehicle and results in a loss relative to the output of the axle motor 15.

[0063] Compared to the torque transmission device of Patent Document 1, the device of Patent Document 1 and the torque vectoring device 500 of this embodiment are the same in that they both incur losses when a negative yaw moment occurs. However, the device of Patent Document 1 uses a friction clutch for braking, which raises concerns about reduced reliability, whereas this embodiment does not have a braking element such as a friction clutch and brakes one of the left and right wheel axles by adjusting the speed ratio of the planetary reduction gear 30, improving reliability.

[0064] Furthermore, the device of Patent Document 1 uses two yaw control devices, each including a planetary gear mechanism and an actuator, for a pair of left and right wheels. In contrast, in this embodiment, the rotation speed and torque distribution of the left and right wheels can be controlled with a simple configuration using a single mechanism and actuator for a pair of left and right wheels, that is, the planetary reduction gear 30 and the left and right torque distribution motor 55. Therefore, the number of parts is reduced compared to the conventional technology of Patent Document 1.

[0065] (Second and third embodiments) Next, a second embodiment in which the motor shaft is a ring shaft 37 and a third embodiment in which the motor shaft is a carrier shaft 36 will be described. Components substantially the same as those in the first embodiment are given the same reference numerals and will not be described. Figs. 13 and 15 are configuration diagrams corresponding to Fig. 5 of the first embodiment. Figs. 14 and 16 are nomographic diagrams corresponding to the solid lines in Fig. 8 of the first embodiment, showing the speed ratios of three shafts in a configuration in which the left and right wheels are configured to have the same rotation speed when the motor shaft is stationary. The equations for calculating the rotation speed and reduction ratio of each shaft are appropriately changed from those in the first embodiment.

[0066] A torque vectoring device 502 according to the second embodiment will be described with reference to Figures 13 and 14. In the torque vectoring device 502 according to the second embodiment, a left / right torque distribution motor 55 is connected to a ring shaft 37. For example, the left / right torque distribution motor 55 has a hollow cylindrical shaft, and is configured so that the sun shaft 35 passes through the inside of the shaft.

[0067] The left wheel transmission mechanism 410 is made up of a carrier shaft transmission gear 46 connected to the carrier shaft 36, and a left wheel shaft gear 41. The right wheel transmission mechanism 420 is made up of a sun shaft transmission gear 45 connected to the sun shaft 35, and a right wheel shaft gear 42. A special structure is required to provide the sun shaft transmission gear 45 which passes through the left and right torque distribution motor 55 and connects to the sun shaft 35.

[0068] The collinear diagram shows the state where the ring shaft rotation speed ωc is 0 (ωc=0, ωa>0, ωp>0). The reduction ratios XL, XR of the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 are set so that the rotation speeds ωTL, ωTR of the left and right wheels are equal at this time. The distance on the collinear diagram between the sun shaft 35 and the carrier shaft 36 connected to the left and right wheels is relatively large, and the difference between the rotation speeds ωa, ωp of the two shafts is relatively large. For this reason, it becomes necessary to set the difference between the reduction ratios XL, XR of the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 to be relatively large.

[0069] A torque vectoring device 503 of the third embodiment will be described with reference to Figures 15 and 18. In the torque vectoring device 503 of the third embodiment, a left and right torque distribution motor 55 is connected to the carrier shaft 36. The left wheel transmission mechanism 410 is composed of a sun shaft transmission gear 45 connected to the sun shaft 35 and a left wheel axle gear 41. The right wheel transmission mechanism 420 is composed of a ring shaft transmission gear 47 connected to the ring shaft 37, a counter gear 48, and a right wheel axle gear 42. The counter gear 48 is provided to reverse the direction of rotation.

[0070] The collinear diagram shows a state where the carrier shaft rotation speed ωp is 0 (ωp=0, ωa>0, ωc<0). The reduction ratios XL and XR of the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 are set so that the rotation speeds ωTL and ωTR of the left and right wheels are equal at this time. In this example, the ring shaft rotation speed ωc is negative, and when the right wheel 92 is rotated in the same direction as the left wheel 91, the reduction ratio XR of the right wheel transmission mechanism 420 becomes negative. Therefore, a counter gear 48 is required between the ring shaft transmission gear 47 and the right wheel axle gear 42. Conversely, when the collinear diagram slopes upward to the right (ωp=0, ωa<0, ωc>0), a counter gear should be provided between the sun shaft transmission gear 45 of the left wheel transmission mechanism 410 and the left wheel axle gear 41.

[0071] (Other embodiments) (a) The torque vectoring device 500 may be applied to a vehicle in which the rear wheels are driving wheels and the front wheels are non-driving wheels, such as an FR vehicle, as opposed to the FF vehicle shown in FIG. 1. For example, in an FF vehicle, the torque vectoring device may be provided only for the driving wheels, and not for the non-driving wheels. The torque vectoring device 500 may be applied not only to a four-wheel vehicle having two pairs of left and right wheels, but also to a vehicle having six or more wheels having three or more pairs of left and right wheels. The term "vehicle" is not limited to vehicles that can run on public roads, but also includes AGVs that run in factories. The AGV 903 illustrated in FIG. 11(b) has torque vectoring devices provided only on the driving wheels 91, 92 located on the left and right of the center of gravity.

[0072] To encapsulate these vehicle examples, the 2WD (FF vehicle) 901 in Fig. 1, the 4WD 902 in Fig. 2, and the AGV 903 in Fig. 11(b) are all generalized as "vehicles having one or more pairs of drive wheels among multiple pairs of left and right wheels." In the vehicles 901-903, the vehicle driving control system includes one or more axle power sources 15, one or more differentials 20 that transmit torque generated by the axle power sources to the drive wheels, an axle power source control unit 17 that controls the rotation of the axle power sources, and one or more torque vectoring devices 500D provided corresponding to the drive wheels.

[0073] 1 is generalized to a vehicle having one pair of drive wheels and one or more pairs of driven wheels among multiple pairs of left and right wheels. The vehicle driving control system in the vehicle 901 includes an axle power source 15, a differential 20 that transmits torque generated by the axle power source to the drive wheels, an axle power source control unit 17 that controls the rotation of the axle power source, and a total of two or more torque vectoring devices 500D, 500N provided corresponding to the drive wheels and driven wheels, respectively.

[0074] (b) The torque vectoring device 500 is not limited to vehicles in which the "axle power source" is the axle motor 15, and may be applied to engine vehicles and hybrid vehicles. An engine may be used as the "axle power source" instead of or in addition to the axle motor 15. In response to this, the engine control unit may function as the "axle power source control unit."

[0075] (c) In the torque vectoring devices 501-503 of the first to third embodiments, the left wheel transmission mechanism 410 and the right wheel transmission mechanism 420 may be appropriately reversed. Therefore, the "left wheel transmission mechanism and the right wheel transmission mechanism" are generalized as "first wheel transmission mechanism and the second wheel transmission mechanism" that respectively connect one and the other of the two shafts other than the motor shaft of the planetary reduction gear 30 to one and the other of the left and right wheel axles.

[0076] (d) As described above, the planetary reducer 30 may be a 3K or KHV type planetary gear mechanism or a compound planetary gear mechanism other than the 2KH type.

[0077] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention.

[0078] The disclosure regarding "a torque vectoring device configured so that the rotation speeds of the left and right wheels are equal when the motor shaft is stationary" and the disclosure regarding "a torque vectoring device in which the motor shaft is a sun shaft" may be combined with each other.

[0079] Each control unit (distribution motor control unit, axle power source control unit) and its method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, each control unit and its method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, each control unit and its method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0080] 15....Axle motor (axle power source), 17 Axle motor control unit (axle power source control unit), 20... Differential, 30 Planetary reducer, 31 sun gear, 32 planetary carrier, 33 ring gear, 35... sun shaft, 36... carrier shaft, 37... ring shaft, 410... Left wheel (first wheel) transmission mechanism, 420... Right wheel (second wheel) transmission mechanism, 55... Left and right torque distribution motor, 57... Distribution motor control unit, 500 (501~503) ···Torque vectoring device, 901, 90... vehicle, 903... AGV (vehicle).

Claims

1. A torque vectoring device that controls the rotation speed and torque distribution of a pair of left and right wheels that constitute driving wheels or driven wheels of a vehicle (901-903), a planetary reducer (30) including three shafts: a sun shaft (35) which is the shaft of a sun gear (31), a carrier shaft (36) which is the shaft of a planetary carrier (32), and a ring shaft (37) which is the shaft of a ring gear (33); a left-right torque distribution motor (55) that is connected directly or via a reduction gear to one motor shaft selected from the three shafts of the planetary reduction gear and adjusts the rotation speed of the two shafts other than the motor shaft by changing the rotation speed of the motor shaft; a first wheel transmission mechanism (410) and a second wheel transmission mechanism (420) that respectively connect one and the other of the two shafts other than the motor shaft of the planetary reduction gear to one and the other of the left and right wheel shafts; a distribution motor control unit (57) that controls the driving of the left and right torque distribution motors based on a request for vehicle operation instructed from an external source; A torque vectoring device comprising:

2. The torque generated by the axle power source (15) is applied to the left and right wheels as the drive wheels of the vehicle, the torque being transmitted via a differential (20); The torque vectoring device of claim 1 , wherein the torque generated by the axle power source is transmitted to the planetary reduction gear via the first wheel transmission mechanism and the second wheel transmission mechanism.

3. 3. The torque vectoring device according to claim 1, wherein the rotation speeds of the left and right wheels are equal when the motor shaft is stationary.

4. The torque vectoring device of claim 1 or 2, wherein the motor shaft is the sun shaft.

5. This is applied to a vehicle (901-903) having one or more pairs of drive wheels among multiple pairs of left and right wheels, one or more axle power sources (15); one or more differentials (20) for transmitting torque generated by the axle power source to the drive wheels; an axle power source control unit (17) for controlling the rotation of the axle power source; One or more torque vectoring devices (500D) according to claim 1 provided corresponding to the drive wheels; Including, A vehicle driving control system that controls the straight-line or cornering movement of the vehicle by distributing the rotation speed and torque of the left and right wheels by the torque vectoring device.

6. This is applied to a vehicle (901) having a pair of drive wheels and one or more pairs of driven wheels among multiple pairs of left and right wheels, An axle power source (15); a differential (20) for transmitting torque generated by the axle power source to the drive wheels; an axle power source control unit (17) for controlling the rotation of the axle power source; A total of two or more torque vectoring devices (500D, 500N) according to claim 1 provided corresponding to the driving wheels and the driven wheels, respectively; Including, A vehicle driving control system that controls the straight-line or cornering movement of the vehicle by distributing the rotation speed and torque of the left and right wheels by the torque vectoring device.

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