Vehicle control device

Abstract

To suppress resonance even when a stepless transmission is shifted in the process of changing drive-force source torque.SOLUTION: In a process of changing engine torque (drive-force source torque) Te at an initially set torque change rate Rte0, a torque amplitude prediction value Atdsx being a prediction value of an amplitude ΔTds of torque variation generated in DS (drive shaft) torque Tds in association with a change in a resonance frequency caused by a change in a shift ratio γ of the stepless transmission is calculated. When the torque amplitude prediction value Atdsx changes in excess of a permissible value α1 (time t4), a torque change rate Rte is changed to Rtex. Consequently, the increase of the DS torque amplitude ΔTds can be suppressed regardless of a change in resonance frequency due to a change in a shift ratio γ of the stepless transmission.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vehicle control device, and more particularly to a technique for controlling changes in torque of a driving power source so as to suppress resonance of the vehicle. [Background technology]

[0002] There is known a vehicle control device that relates to (a) a vehicle having a driving force source and a transmission disposed in a power transmission path between the driving force source and drive wheels, and (b) a driving force source torque change control unit that sets a torque change rate based on a resonance frequency of the power transmission path when changing the driving force source torque, which is the torque of the driving force source, and changes the driving force source torque at the torque change rate. Patent Document 1 describes an example of such a device, which changes the driving force source torque to a target driving force source torque in a time that is the reciprocal of the resonance frequency of the power transmission path, and suppresses resonance caused by changes in the driving force source torque. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-99059 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle having a transmission in a power transmission path, the resonant frequency changes with a change in the gear ratio of the transmission, so that if the transmission is shifted in the process of changing the torque of the driving power source, the resonant frequency may change and the resonance suppression effect may not be adequately obtained. In particular, in the case of a continuously variable transmission that can continuously change the gear ratio, the resonant frequency changes continuously with the change in the gear ratio, and so it is problematic how to deal with this.

[0005] FIG. 15 is a diagram for explaining the reason why resonance is likely to occur due to a change in the resonance frequency. The solid line in FIG. 15 shows an example of the relationship between the DS torque amplitude (the maximum amplitude of the variation of the torque Tds of the drive shaft) ΔTds and the rise time ts of the driving force source torque during acceleration when the driving force source torque is started from the state where the accelerator is OFF in accordance with the accelerator depression operation, that is, during so-called tip-in acceleration. When the rise time ts is the time ts0 which is the reciprocal (1 / fr0) of the resonance frequency fr0, the DS torque amplitude ΔTds becomes extremely small. Therefore, resonance can be suppressed by starting the driving force source torque at the rise time ts0. However, when the continuously variable transmission is downshifted during the process of starting the driving force source torque and the resonance frequency changes from fr0 to fr1 (<fr0), the characteristics of the DS torque amplitude ΔTds change as shown by the broken line. For this reason, when the driving force source torque is started at the original rise time ts0, the DS torque amplitude ΔTds increases as shown by the arrow Q. Note that the rise time ts1 in FIG. 15 is the time which is the reciprocal (1 / fr1) of the resonance frequency fr1. Also, when the continuously variable transmission is upshifted during the process of stopping the driving force source torque during the accelerator return operation, there is a possibility that the torque amplitude of the power transmission path increases due to the change in the resonance frequency.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to suppress resonance even when the transmission is shifted during the process of changing the driving force source torque.

Means for Solving the Problems

[0007] In order to achieve this object, the first invention relates to (a) a vehicle having a driving force source and a continuously variable transmission arranged in a power transmission path between the driving force source and drive wheels, and (b) a vehicle control device having a driving force source torque change control unit that, when changing the torque of the driving force source, sets a torque change rate based on a resonance frequency of the power transmission path determined according to the gear ratio of the continuously variable transmission, and changes the driving force source torque at that torque change rate, wherein (c) the driving force source torque change control unit calculates the amplitude of torque fluctuation predicted to occur in the power transmission path due to a change in resonance frequency caused by a change in the gear ratio of the continuously variable transmission during the process of changing the driving force source torque at the torque change rate, and changes the torque change rate if the calculated torque amplitude predicted value changes beyond a predetermined reset condition.

[0008] A second invention is characterized in that, in the vehicle control device of the first invention, the driving force source torque change control unit sequentially calculates, as the torque amplitude prediction value, an amplitude Atdsx of torque fluctuation predicted to occur in the drive shaft if the change in the driving force source torque is currently stopped, based on the elapsed time tax after the start of torque change control that changes the driving force source torque at the torque change rate, an amount of change in the driving force source torque after the start of the torque change control, and a resonance frequency frx that changes in accordance with a change in the gear ratio of the continuously variable transmission, in accordance with the following equation (1): Atdsx=Tix×[K1 / (tax×frx)]× sin(tax×frx) ···(1)

[0009] Here, K1 is a coefficient. The change amount Tix of the driving force source torque can be replaced with the change amount of torque of a part having a certain relationship with the driving force source torque, such as the change amount of input torque to a continuously variable transmission or the change amount of input torque in a drive shaft which is a part where resonance occurs.

[0010] A third invention is characterized in that, in the vehicle control device of the first or second invention, the driving force source torque change control unit sets the torque change rate at the beginning of torque change control that changes the driving force source torque at the torque change rate so that the driving force source torque is changed to the target driving force source torque in a time that is the reciprocal of the resonance frequency of the power transmission path.

[0011] A fourth invention is characterized in that, in the control device for a vehicle according to the first or second invention, the driving force source torque change control unit calculates, at the start of torque change control that changes the driving force source torque at the torque change rate, an initial torque amplitude predicted value Atds0, which is the amplitude of torque fluctuation predicted to occur in the drive shaft, using a rise-up time ts for increasing the driving force source torque to the target driving force source torque as a variable, based on a torque change amount Ti0 when increasing the driving force source torque to the target driving force source torque and an initial resonance frequency fr0 that is the resonance frequency of the power transmission path at the start of control, in accordance with the following equation (2); and from the relationship between the calculated initial torque amplitude predicted value Atds0 and the rise-up time ts, an initial rise-up time ts0 at which the initial torque amplitude predicted value Atds0 becomes a predetermined target value is determined, and the torque change rate is set so that the driving force source torque is increased to the target driving force source torque at the initial rise-up time ts0. Atds0=Ti0×〔K2 / (ts×fr0)〕× sin (ts×fr0) ···(2)

[0012] where K2 is a coefficient. The torque change amount Ti0 can be replaced with the change amount of torque of a portion having a certain relationship with the torque of the driving force source, such as the change amount of input torque to a continuously variable transmission or the change amount of input torque to a drive shaft that is a resonance occurrence portion. Effect of the Invention

[0013] In such a vehicle control device, in the process of changing the driving force source torque at a set torque change rate, the amplitude of the torque fluctuations occurring in the power transmission path due to changes in resonance frequency caused by changes in the gear ratio of the continuously variable transmission is predicted and calculated, and if the torque amplitude predicted value changes beyond the re-set condition, the torque change rate of the driving force source is changed, so that an increase in the torque amplitude in the power transmission path can be suppressed regardless of changes in resonance frequency caused by changes in the gear ratio of the continuously variable transmission.

[0014] In the second invention, the torque amplitude predicted value Atdsx in the case where the change in the driving force source torque is currently stopped is calculated according to equation (1) based on the elapsed time tax after the start of torque change control, the amount of change Tix in the driving force source torque after the start of torque change control, and the resonance frequency frx that changes in accordance with the change in the gear ratio of the continuously variable transmission.Therefore, the increase in the torque amplitude of the drive shaft caused by the change in the resonance frequency fr can be appropriately predicted, and the driving force source torque can be controlled so as to suppress the increase in the torque amplitude.

[0015] In the third aspect of the present invention, the torque change rate is set so that the driving force source torque can be changed to the target torque in a time that is the reciprocal of the resonance frequency of the power transmission path, so that resonance of the power transmission path can be appropriately suppressed.

[0016] In the fourth invention, an initial torque amplitude prediction value Atds0 is calculated according to equation (2) using a rise time ts for increasing the driving force source torque to the target driving force source torque as a variable, an initial rise time ts0 at which the initial torque amplitude prediction value Atds0 becomes a predetermined target value is obtained from the relationship between the initial torque amplitude prediction value Atds0 and the rise time ts, and a torque change rate is set so that the driving force source torque is increased to the target driving force source torque at the initial rise time ts0. Therefore, torque fluctuations of a predetermined amplitude equivalent to the target value are generated while suppressing excessive resonance of the drive shaft caused by changes in the driving force source torque, and the driver can feel an increase in the driving force of the vehicle due to the driver's operation of the accelerator, etc. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram for explaining a drive device for a vehicle to which the present invention is applied, showing essential parts of a control system. [Diagram 2] 4 is a flowchart specifically illustrating the operation of an engine torque change control unit that is functionally provided in the electronic control device of FIG. [Diagram 3] 3 is a diagram illustrating a resonance frequency fr determined according to the gear ratio γ in step S2 of FIG. 2. FIG. [Figure 4] FIG. 11 is a diagram illustrating the relationship between engine torque change time tf and DS torque amplitude ΔTds. [Diagram 5] 3 is a diagram illustrating variables used in an arithmetic expression for calculating a torque amplitude predicted value Atdsx in step S3 of FIG. 2. [Figure 6] 3 is an example of a time chart illustrating changes in the operating state of each part when control for changing the torque change rate is performed according to the flowchart of FIG. 2 when engine torque is raised during tip-in acceleration. [Figure 7] FIG. 1 is a diagram illustrating the relationship between the input torque rise amount Tis, the transmission torque amplitude At, the rise time ts, and the period T of the resonance frequency in a spring-mass system with one degree of freedom. [Figure 8] FIG. 1 is a diagram explaining the theoretical formula when treating a CVT-equipped vehicle as a spring-mass system with multiple degrees of freedom. [Figure 9] This figure explains the change in input torque when the input torque ramp amount Tis is ramped up with a ramp time ts in order to generalize a spring-mass system with multiple degrees of freedom. [Figure 10] This is an example of the characteristics of the transmission torque amplitude At and the rise time ts derived from a model with the speed ratio γ divided in increments of 0.1, assuming the input torque change in FIG. [Figure 11] 11 is an example of the characteristics of the transmission torque amplitude At and the rise time ts obtained by re-deriving the characteristics of FIG. 10 based on a theoretical formula of one degree of freedom. [Figure 12] FIG. 12 is a diagram for explaining a theoretical formula expressing the characteristics of FIG. 11 . [Figure 13]5 is a flowchart illustrating another example of the torque change control executed by the engine torque change control unit of FIG. [Figure 14] FIG. 14 is a diagram for explaining the procedure for determining the initial rise time ts0 based on the target value β of the torque amplitude in step R2 of FIG. 13. [Figure 15] FIG. 13 is a diagram for explaining the reason why the DS torque amplitude ΔTds increases with a change in the resonant frequency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention is applicable to, for example, engine-driven vehicles equipped with an engine (internal combustion engine) as a driving force source, but may also be applied to hybrid electric vehicles equipped with an engine and an electric motor as a driving force source, and electric vehicles equipped with only an electric motor as a driving force source. At least a continuously variable transmission is provided in the power transmission path, and for example, a belt-type continuously variable transmission and a forward / reverse switching device having a forward clutch and a reverse brake are provided in series or in parallel. As the continuously variable transmission, other types of continuously variable transmissions such as an electric type or a toroidal type having a differential mechanism and a rotating machine for differential control may also be used.

[0019] The driving force source torque change control unit is preferably applied to, for example, tip-in acceleration in which the driving force source torque is suddenly increased in response to an acceleration request from an accelerator-off driven state to an accelerator-on acceleration request, but may also be applied to sudden acceleration due to further depression of the accelerator pedal, or sudden decrease in driving force source torque due to the release of the accelerator pedal. That is, the driving force source torque change control unit is for suppressing resonance of the power transmission path caused by a sudden increase (start-up) or decrease (decrease) in the driving force source torque, and it is sufficient that the driving force source torque is controlled at a torque change rate set based on the resonance frequency at least during the sudden increase or decrease. Also, if the torque change rate is changed when the torque amplitude prediction value changes beyond the reset condition, the time until the driving force source torque reaches the target driving force source torque is changed.

[0020] For example, when driving force is transmitted from a continuously variable transmission to a drive wheel via a drive shaft, the driving force source torque change control section is configured to predict the amplitude of torque fluctuation occurring in the drive shaft and control the driving force source torque as shown in the above formulas (1) and (2), but the driving force source torque may also be controlled based on the amplitude of torque fluctuation of a power transmission member other than the drive shaft that is provided on the drive wheel side of the continuously variable transmission. In that case, too, formulas (1) and (2) can be used as they are by simply changing the coefficients K1 and K2. EXAMPLES

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified for the purpose of explanation, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately.

[0022] FIG. 1 is a schematic diagram for explaining the schematic configuration of a drive device of a vehicle 8 to which the present invention is applied, in which a plurality of parallel shafts are expanded to be positioned on one plane, and the vehicle includes a power transmission device 10 for a vehicle. The power transmission device 10 for a vehicle is a horizontal type suitable for use in FF (front engine, front drive) vehicles, and the output of an engine 12, which is a driving force source for traveling, is transmitted from a torque converter 14 as a fluid transmission device to a differential gear device 18 via an automatic transmission 16, and distributed to left and right driving wheels 20L, 20R. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The torque converter 14 includes a pump wheel 14p connected to the crankshaft of the engine 12 and a turbine wheel 14t connected to an input shaft 22 of the automatic transmission 16, and transmits power via a fluid (hydraulic oil) and is directly connected by a lock-up clutch LU. A mechanical oil pump 74 is provided on the pump impeller 14p, and is rotationally driven by the engine 12 to output hydraulic pressure, thereby serving as a hydraulic pressure source for a hydraulic control circuit 70 shown by a dashed line. The connection destination, i.e., the installation position, of the oil pump 74 can be changed as appropriate, and an electric oil pump can also be used.

[0023] The hydraulic control circuit 70 is equipped with a hydraulic operation control section 72 constituted by a valve body and the like, and the lockup engagement hydraulic pressure Plu, which is the engagement hydraulic pressure of the lockup clutch LU of the torque converter 14, is regulated and controlled by a linear solenoid valve SLU, and the lockup clutch LU is controlled for engagement and release in response to this lockup engagement hydraulic pressure Plu. The lockup engagement hydraulic pressure Plu controls, for example, the differential pressure between a lockup engagement side oil chamber and a lockup release side oil chamber. The linear solenoid valve SLU is a hydraulic control solenoid valve, and is electrically controlled by an electronic control device 80 to regulate the lockup engagement hydraulic pressure Plu.

[0024] The automatic transmission 16 includes an input shaft 22 connected to a turbine shaft which is an output rotating member of the torque converter 14, a belt-type continuously variable transmission 24 (hereinafter simply referred to as the continuously variable transmission 24) connected to the input shaft 22, a forward / reverse switching device 26 and a gear shift mechanism 28 which are also connected to the input shaft 22 and provided in parallel with the continuously variable transmission 24, an output shaft 30 which is a common output rotating member of the continuously variable transmission 24 and the gear shift mechanism 28, and a reduction gear device 32, and a small-diameter gear 34 of the reduction gear device 32 is meshed with a ring gear 36 of the differential gear device 18. In the automatic transmission 16 configured in this manner, the output of the engine 12 is transmitted from the torque converter 14 to the output shaft 30 via the continuously variable transmission 24, or is transmitted to the output shaft 30 via the forward / reverse switching device 26 and the gear shift mechanism 28 without passing through the continuously variable transmission 24. The power is then distributed from the output shaft 30 through a reduction gear device 32 and a differential gear device 18 to left and right drive shafts 38L, 38R, and then transmitted to drive wheels 20L, 20R.

[0025] In this way, the automatic transmission 16 of this embodiment includes a first power transmission path TP1 that transmits the output of the engine 12 from the input shaft 22 to the output shaft 30 via the forward / reverse switching device 26 and the gear shift mechanism 28, and a second power transmission path TP2 that transmits the output of the engine 12 from the input shaft 22 to the output shaft 30 via the continuously variable transmission 24, and these power transmission paths TP1 and TP2 are switched depending on the running state of the vehicle. For this reason, the automatic transmission 16 includes a forward clutch C1 that connects and disconnects (connects and disconnects) the power transmission in the first power transmission path TP1, a reverse brake B1, and a belt running clutch C2 that connects and disconnects the power transmission in the second power transmission path TP2. The first power transmission path TP1 is further provided with a synchromesh clutch Cd in series with the forward / reverse switching device 26 and the gear shift mechanism 28, specifically downstream of them.

[0026] The forward / reverse switching device 26 is mainly constituted by a double-pinion type planetary gear device, in which the carrier 26c is integrally connected to the input shaft 22 and the sun gear 26s is connected to a small diameter gear 42 arranged coaxially and rotatably relative to the input shaft 22, while the ring gear 26r is selectively stopped from rotating via a reverse brake B1 and the carrier 26c and the sun gear 26s are selectively connected via a forward clutch C1. When the forward clutch C1 is engaged and the reverse brake B1 is released, the input shaft 22 is directly connected to the small diameter gear 42 to enter a forward power transmission state, and when the first power transmission path TP1 is established by engaging the synchromesh clutch Cd, forward travel is possible. On the other hand, when the reverse brake B1 is engaged and the forward clutch C1 is released, the small gear 42 is rotated in the reverse direction relative to the input shaft 22, resulting in a reverse power transmission state, and when the synchromesh clutch Cd is engaged to establish the first power transmission path TP1, reverse travel becomes possible. When both the forward clutch C1 and the reverse brake B1 are released, a neutral state is established in which power transmission through the first power transmission path TP1 is interrupted.

[0027] The forward clutch C1 and reverse brake B1 are both multi-plate hydraulic friction engagement devices in which a plurality of friction materials are frictionally engaged by hydraulic cylinders, and their engagement forces, i.e., transmission torque capacities, are continuously adjusted by controlling the C1 engagement oil pressure Pc1 and the B1 engagement oil pressure Pb1 supplied to the hydraulic cylinders through adjustment by linear solenoid valves SL1 and SLU provided in the hydraulic operation control section 72. The linear solenoid valves SL1 and SLU are hydraulic control solenoid valves, and are electrically controlled by the electronic control device 80 to adjust the C1 engagement oil pressure Pc1 and the B1 engagement oil pressure Pb1.

[0028] The gear transmission mechanism 28 includes a small diameter gear 42, a large diameter gear 46 that is non-rotatably mounted on the countershaft 44 and meshes with the small diameter gear 42, and a small diameter idler gear 48 that is coaxially mounted on the countershaft 44 and rotatable relative thereto. A synchromesh clutch Cd is provided between the countershaft 44 and the idler gear 48 to connect and disconnect power transmission therebetween. The synchromesh clutch Cd includes a synchromesh mechanism such as a synchronizer ring. When a clutch hub sleeve 50 is moved in a connecting direction, which is the left direction in FIG. 1, by a hydraulic cylinder (not shown), the idler gear 48 is rotated synchronously with the countershaft 44 via the synchronizer ring. When the clutch hub sleeve 50 is further moved, the idler gear 48 is connected to the countershaft 44 via spline teeth provided on the inner peripheral surface of the clutch hub sleeve 50 so as to be non-rotatable relative thereto. The hydraulic cylinder of the synchronous mesh clutch Cd is supplied with the Cd engagement hydraulic pressure Pcd, which is adjusted and controlled by a linear solenoid valve SL1 provided in the hydraulic operation control section 72, and the synchronous mesh clutch Cd is engaged in synchronous mesh based on the Cd engagement hydraulic pressure Pcd. The hydraulic cylinder of the synchronous mesh clutch Cd is also supplied with the line hydraulic pressure PL as the Cd engagement hydraulic pressure Pcd as it is, and the synchronous mesh clutch Cd is maintained in an engaged state. The line hydraulic pressure PL is adjusted in response to, for example, the accelerator opening Acc, which is the required output amount, and the throttle valve opening θth, which corresponds to the engine torque. The linear solenoid valve SL1 is a hydraulic control solenoid valve, and adjusts the Cd engagement hydraulic pressure Pcd by being electrically controlled by the electronic control device 80.

[0029] The idler gear 48 is meshed with a large diameter gear 58 provided on the output shaft 30, and when either the forward clutch C1 or the reverse brake B1 is engaged and the synchromesh clutch Cd is connected, the output of the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the forward / reverse switching device 26, the gear transmission mechanism 28, the idler gear 48, and the large diameter gear 58 in this order, thereby establishing a first power transmission path TP1. Note that speed change (reduction) also occurs between the small diameter idler gear 48 and the large diameter gear 58, and it can be considered that the gear transmission mechanism 28 is composed of these and other elements.

[0030] The continuously variable transmission 24 includes a primary pulley 60 with a variable effective diameter provided on the input shaft 22, a secondary pulley 64 with a variable effective diameter provided on a pulley rotating shaft 62 coaxial with the output shaft 30, and a transmission belt 66 wound around the pair of variable pulleys 60, 64, and power is transmitted through friction between the pair of variable pulleys 60, 64 and the transmission belt 66. The pair of variable pulleys 60, 64 include hydraulic cylinders 60c, 64c, respectively, as hydraulic actuators that apply thrust to change the V-groove width, and for example, the primary hydraulic pressure Ppri supplied to the hydraulic cylinder 60c is controlled by a linear solenoid valve SLP provided in the hydraulic operation control unit 72, thereby changing the V-groove width of both variable pulleys 60, 64, changing the wrapping diameter (effective diameter) of the transmission belt 66, and continuously changing the speed ratio γ. For example, the primary hydraulic pressure Ppri is controlled by the linear solenoid valve SLP so that the rotational speed (input rotational speed) Nin of the input shaft 22, which is the rotational speed of the primary pulley 60, becomes a predetermined target rotational speed corresponding to the gear ratio γ. In addition, the secondary hydraulic pressure Psec supplied to the hydraulic cylinder 64c is regulated and controlled by the linear solenoid valve SLS provided in the hydraulic operation control unit 72, thereby adjusting the belt clamping pressure so that the transmission belt 66 does not slip. The linear solenoid valves SLP and SLS are hydraulic control solenoid valves, and are electrically controlled by the electronic control device 80 to regulate the primary hydraulic pressure Ppri and the secondary hydraulic pressure Psec, respectively.

[0031] The output shaft 30 is arranged coaxially with the pulley rotating shaft 62 so as to be rotatable relative thereto, and the belt running clutch C2 provided between the output shaft 30 and the secondary pulley 64 connects and disconnects the power transmission between the output shaft 30 and the secondary pulley 64. When the belt running clutch C2 is engaged, the output of the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the continuously variable transmission 24, and the second power transmission path TP2 is established, enabling forward travel. The belt running clutch C2 is a multi-plate type friction engagement device in which a plurality of friction materials are frictionally engaged by a hydraulic cylinder, and the C2 engagement hydraulic pressure Pc2 supplied to the hydraulic cylinder is adjusted by a linear solenoid valve SL2 provided in the hydraulic operation control unit 72, thereby continuously adjusting the engagement force, i.e., the transmission torque capacity. The linear solenoid valve SL2 is a hydraulic control solenoid valve, and is electrically controlled by the electronic control device 80 to adjust the C2 engagement hydraulic pressure Pc2.

[0032] In such a vehicle power transmission device 10, the gear ratio g of the first power transmission path TP1 determined by the gear ratio of the gear shift mechanism 28 and the like is greater than the maximum value γmax of the gear ratio γ of the second power transmission path TP2, and the vehicle runs in a gear running mode using the first power transmission path TP1 when starting or running under high load, and is switched to a belt running mode using the second power transmission path TP2 with an increase in the vehicle speed V or a decrease in the required driving force. That is, the gear running mode with the gear ratio g corresponds to a first gear stage, and the belt running mode in a state where the gear ratio γ of the continuously variable transmission 24 is at or close to the maximum value γmax corresponds to a second gear stage. Then, a mode switch (upshift) from the gear running mode (gear ratio g) to the belt running mode with the second gear ratio γs is performed by a clutch-to-clutch shift in which the forward clutch C1 is released and the belt running clutch C2 is engaged. Furthermore, mode switching (downshift) from the belt driving mode at the second gear ratio γs to the gear driving mode (gear ratio g) is performed by a clutch-to-clutch shift in which the belt driving clutch C2 is released and the forward clutch C1 is engaged. The gear ratios g and γ are the ratio (Nin / Nout) of the input rotation speed Nin to the output rotation speed (rotation speed of the output shaft 30), and both the gear ratios g and γs are greater than 1.0, so that the output shaft 30 is rotated at a reduced speed relative to the input shaft 22. The output rotation speed Nout corresponds to the vehicle speed V, and the input rotation speed Nin coincides with the turbine rotation speed Nt.

[0033] Such a vehicle 8 includes an electronic control device 80 as a controller for controlling the output of the engine 12, switching between a plurality of driving modes of the vehicle power transmission device 10, shift control and belt clamping pressure control of the continuously variable transmission 24, and engagement / disengagement control of the lock-up clutch LU. The electronic control device 80 includes a so-called microcomputer having a CPU, a ROM, a RAM, an input / output interface, and performs signal processing according to a program prestored in the ROM while utilizing the temporary storage function of the RAM. That is, the electronic control device 80 functionally includes an engine control unit 82, a driving mode switching control unit 86, and a CVT (Continuously Variable Transmission) shift control unit 88. The electronic control device 80 corresponds to a control device of the vehicle 8, and includes a plurality of computers for engine control, hydraulic control, and the like, as necessary.

[0034] The electronic control device 80 is supplied with a signal representing the lever position Lpo, which is the operating position of the shift lever 90, from a lever position sensor 92, and also with various information required for various controls, such as signals representing the accelerator opening Acc, which is the operating amount of the accelerator pedal 93, the turbine rotation speed Nt, and the output rotation speed Nout, from an accelerator opening sensor 94, a turbine rotation speed sensor 96, an output rotation speed sensor 98, etc. The shift lever 90 can be operated to a P position, an R position, an N position, a D position, etc., as the lever position Lpo. By operating the shift lever 90 to the P position, the P range for parking is selected, by operating it to the R position, the N range for cutting off the power transmission is selected, and by operating it to the N position, the D range for forward driving is selected. The accelerator opening Acc corresponds to the amount of driving force required by the driver. The electronic control device 80 also outputs a hydraulic control command signal Sp for controlling the solenoid valves of the hydraulic operation control unit 72, as well as an engine control command signal Se for controlling the engine 12. The engine 12 is equipped with an engine control device 76 including an electronic throttle valve, a fuel injection device, an ignition device, etc., and the engine torque Te, etc. are controlled by controlling the engine control device 76 with an engine control command signal Se.

[0035] The engine control unit 82 sets a target engine torque Tetgt based on the accelerator opening Acc, for example, and outputs an engine control command signal Se to control the throttle valve opening, the fuel injection amount, etc. so as to increase or decrease the engine torque Te, which is the torque of the engine 12, according to the target engine torque Tetgt. Also, various modes are possible, such as calculating a required driving force Frdem based on the accelerator opening Acc and the vehicle speed V, setting a target engine torque Tetgt at which the required driving force Frdem is obtained, and controlling the engine 12 so as to obtain the target engine torque Tetgt.

[0036] The driving mode switching control unit 86 executes a driving mode switching control for switching between a gear driving mode in which the vehicle runs using the first power transmission path TP1 and a belt driving mode in which the vehicle runs using the second power transmission path TP2 during forward driving such as in the D range. The gear driving mode and the belt driving mode are switched, for example, according to a shift line for switching between the first gear stage and the second gear stage in a shift map of a normal stepped transmission. This shift map is determined based on the driving state such as the accelerator opening Acc and the vehicle speed V, and is determined so that, for example, when the accelerator opening Acc is small and the vehicle speed V is high, an upshift is performed from the gear driving mode to the belt driving mode, and when the accelerator opening Acc is large and the vehicle speed V is low, a downshift is performed from the belt driving mode to the gear driving mode. That is, at low vehicle speeds such as when the vehicle starts, the vehicle runs in the gear driving mode, and at a predetermined vehicle speed or higher, the vehicle runs in the belt driving mode. Specifically, when switching the mode to upshift from the gear driving mode to the belt driving mode, the hydraulic control command signal Sp is output to execute a clutch-to-clutch shift in which the forward clutch C1 is released and the belt driving clutch C2 is engaged with the speed ratio γ of the continuously variable transmission 24 set to the second speed ratio γs. Also, when switching the mode to downshift from the belt driving mode to the gear driving mode, the hydraulic control command signal Sp is output to execute a clutch-to-clutch shift in which the belt driving clutch C2 is released and the forward clutch C1 is engaged with the speed ratio γ of the continuously variable transmission 24 set to the second speed ratio γs.

[0037] The CVT shift control unit 88 executes shift control of the continuously variable transmission 24 in the belt driving mode in the D range. This shift control is performed by calculating a target input rotation speed Nintgt according to a shift map determined in advance based on the driving conditions such as the accelerator opening Acc and the vehicle speed V, and outputting a hydraulic control command signal Sp to increase or decrease the gear ratio γ of the continuously variable transmission 24 so that the actual input rotation speed Nin becomes the target input rotation speed Nintgt. Specifically, the gear ratio γ is controlled so that, for example, the larger the accelerator opening Acc and the lower the vehicle speed V, the higher the input rotation speed Nin becomes, in other words, the lower the gear ratio γ becomes, and the smaller the accelerator opening Acc and the higher the vehicle speed V becomes, in other words, the higher the gear ratio γ becomes. This shift control of the continuously variable transmission 24 is basically performed within the range of the second gear ratio γs to the minimum gear ratio γmin. The CVT shift control unit 88 changes the gear ratio γ continuously between the second gear ratio γs and the minimum gear ratio γmin, for example, but it is also possible to change the gear ratio γ in steps like a stepped transmission.

[0038] Here, if the engine torque Te is suddenly increased or decreased with a change in the accelerator opening Acc, the torque change may cause resonance in the power transmission path, for example, the drive shafts 38L, 38R, etc. For this reason, Patent Document 1 and others have proposed controlling the torque change rate Rte of the engine torque Te based on the resonance frequency fr of the power transmission path to reduce resonance. However, since this resonance frequency fr varies depending on the gear ratio γ of the continuously variable transmission 24 as shown in FIG. 3, if the continuously variable transmission 24 is shifted in the process of increasing or decreasing the engine torque Te, the resonance frequency fr may change and the resonance suppression effect may not be obtained appropriately. In contrast, in this embodiment, an engine torque change control unit 84 is provided in the engine control unit 82 so that a predetermined resonance suppression effect can be obtained regardless of the change in the resonance frequency fr even if the continuously variable transmission 24 is shifted in the process of increasing or decreasing the engine torque Te. The engine torque change control unit 84 corresponds to a driving force source torque change control unit.

[0039] The engine torque change control unit 84 executes signal processing according to steps S1 to S7 of the flowchart in Fig. 2 (hereinafter, the steps will be omitted and simply referred to as S1 to S7. The same applies to other flowcharts). The flowchart in Fig. 2 is executed when the vehicle is traveling in the belt driving mode in the D range, and in S1, it is determined whether or not an input torque change has occurred due to accelerator operation or the like. That is, it is determined whether or not the engine torque Te is suddenly decreased by increasing or decreasing by more than a predetermined change width, and if it is not suddenly decreased, the process ends as it is, but if it is suddenly decreased, S2 and thereafter are executed. For example, it is determined whether or not the engine torque Te is being accelerated by more than a predetermined amount in response to depression of the accelerator pedal 93 from a coasting state with the accelerator opening Acc being approximately 0 and the accelerator OFF.

[0040] In S2, the torque change rate Rte, which is the rate of change when the engine torque Te is increased or decreased, is determined based on the resonance frequency fr of the power transmission path, specifically, the resonance frequency fr of the drive shafts 38L and 38R. Since the resonance frequency fr changes according to the gear ratio γ of the continuously variable transmission 24, the resonance frequency fr is first calculated according to the gear ratio γ. That is, the input rotation speed Nin (=Nt) is divided by the output rotation speed Nout to calculate the initial gear ratio γ0, which is the current (control start time) gear ratio γ of the continuously variable transmission 24, and the initial resonance frequency fr0 is calculated from a predetermined relationship as shown in FIG. 3. The relationship between the gear ratio γ and the resonance frequency fr is determined for each vehicle 8, for example, but generally, as shown in FIG. 3, the resonance frequency fr decreases as the gear ratio γ increases. Then, an initial torque change rate Rte0 at the start of control is calculated so that the engine torque Te is changed to the target engine torque Tetgt in an initial change time tf0 (=1 / fr0) which is the reciprocal (1 / fr0) of the initial resonance frequency fr0. For example, as shown in Fig. 5, if the current engine torque Te is Te0 and the target engine torque Tetgt is Te1, then the torque change amount Ti0 = (Te1 - Te0), and the initial torque change rate Rte0 (=Ti0 / tf0) is obtained by dividing the torque change amount Ti0 by the initial change time tf0.

[0041] Then, the engine 12 is controlled so that the engine torque Te is changed at the calculated initial torque change rate Rte0. This makes it possible to quickly increase or decrease the engine torque Te while suppressing the DS torque amplitude ΔTds, which is the amplitude of the torque (DS torque) Tds of the drive shafts 38R and 38L. FIG. 4 is a diagram for explaining the relationship between the change time tf, which is the time required to change the engine torque Te to the target engine torque Tetgt, and the DS torque amplitude ΔTds. Regardless of the magnitude of the torque change amount corresponding to the torque change amount Ti0 in FIG. 5, the DS torque amplitude ΔTds becomes minimal when the change time tf is the reciprocal time (1 / fr) of the resonance frequency fr. In other words, if the engine torque Te is increased or decreased at the initial torque change rate Rte0 calculated by dividing the torque change amount Ti0 by the initial change time tf0, which is the reciprocal of the initial resonance frequency fr0, the DS torque amplitude ΔTds can be maintained at a minimal state and the engine torque Te can be changed to the target engine torque Tetgt.

[0042] Fig. 6 is an example of a time chart when engine torque Te rise control is performed according to the flowchart of Fig. 2 during tip-in acceleration, and time t1 is the time when accelerator pedal 93 is depressed from the coasting state with the accelerator OFF. Then, target engine torque Tetgt=Te1 is calculated based on accelerator opening Acc, and initial change time tf0 is calculated from initial resonance frequency fr0 obtained according to initial gear ratio γ0. Initial torque change rate Rte0 (=Ti0 / tf0) is determined from initial change time tf0 and torque change amount Ti0=(Te1-Te0). At time t2, torque change control is started to rise engine torque Te at initial torque change rate Rte0.

[0043] When such torque change control is started, the steps from S3 on in FIG. 2 are executed. In S3, the torque amplitude prediction value Atdsx, which is the amplitude of the torque fluctuation of the DS torque Tds predicted to occur when the change in the engine torque Te is stopped at the current time tx, is calculated according to the above formula (1) based on the elapsed time tax after the start of the torque change control, the change amount Tix of the engine torque Te after the start of the torque change control, and the resonance frequency frx at the current time tx determined according to the gear ratio γx of the continuously variable transmission 24. FIG. 5 is a diagram illustrating the elapsed time tax, the change amount Tix of the engine torque Te, and the gear ratio γx, where time t1 is the start time of the torque change control, and time t2 is the initially scheduled control end time, that is, the control end time when there is no change in the gear ratio γ. This FIG. 5 shows a case where the continuously variable transmission 24 is downshifted and the gear ratio γ is increased during the process of the torque change control to increase the engine torque Te. With this change in the speed ratio γ, the resonance frequency fr changes, for example, as shown in Fig. 3. That is, as the speed ratio γ increases from γ0 to γx, the resonance frequency fr decreases from fr0 to frx.

[0044] The above formula (1) is a calculation formula obtained based on the knowledge shown in Figs. 7 to 12, which considers the torque amplitude etc. during tip-in acceleration. Fig. 7 is a diagram explaining the relationship between the input torque rise amount Tis, the transmitted torque amplitude At, the rise time ts, and the period T of the resonance frequency in a spring-mass system with one degree of freedom, and these variables have the relationship shown in the calculation formula (A). The transmitted torque amplitude At corresponds to the torque amplitude prediction value Atdsx in formula (1), the input torque rise amount Tis corresponds to the amount of change Tix of the engine torque Te in formula (1), the rise time ts corresponds to the elapsed time tax in formula (1), and the period T corresponds to the resonance frequency frx.

[0045] However, in a vehicle equipped with a CVT such as the vehicle 8, the resonance frequency changes with the change in the gear ratio γ, so that the system becomes a spring-mass system with multiple degrees of freedom as shown in FIG. 8, and a complex theoretical formula such as that shown in formula (B) is required. In order to generalize this spring-mass system with multiple degrees of freedom, as shown in FIG. 9, the input torque rise amount Tis is fixed at a constant (100 Nm) and the rise time ts is assumed to be a ramp input, i.e., rise at a constant rate of change. The relationship between the rise time ts and the transmission torque amplitude At is derived from the model by changing the gear ratio γ in increments of 0.1, and the characteristics shown in FIG. 10 are obtained. If the characteristics shown in FIG. 10 are re-derived based on the theoretical formula with one degree of freedom, the characteristics shown in FIG. 11 are obtained. In both the characteristics shown in FIG. 10 and FIG. 11, as the gear ratio γ increases, the rise time ts at which the transmission torque amplitude At becomes minimum becomes longer (to the right in the figure). The characteristic in FIG. 11 can be expressed by theoretical formula (C) in FIG. 12, and by using the input torque rise amount Tis and the resonance frequency fr as variables, the transmission torque amplitude At can be calculated regardless of differences in the input torque rise amount Tis or rise time ts, or changes in the speed ratio γ of the continuously variable transmission 24. The formula (1) is determined based on this theoretical formula (C), and the coefficient K1 is determined according to the hardware specifications of the vehicle 8. The coefficient K1 is determined according to the resonance frequency frx. Also, a different value may be determined as the coefficient K1 depending on whether the engine torque Te increases or decreases.

[0046] Returning to FIG. 2, in S4, it is determined whether the torque amplitude prediction value Atdsx calculated in S3 is greater than a predetermined allowable value α1. That is, when the resonance frequency fr changes with the change in the gear ratio γ, the change time tf (=1 / fr) at which the DS torque amplitude ΔTds becomes minimum changes as is clear from FIG. 4, and the torque amplitude prediction value Atdsx corresponding to the DS torque amplitude ΔTds becomes large. Therefore, if the torque amplitude prediction value Atdsx is equal to or less than the allowable value α1, the torque change control is continued in S6 while maintaining the current torque change rate Rte, and if the torque change rate Rte exceeds the allowable value α1, S5 is executed to recalculate the torque change rate Rte. The allowable value α1 is, for example, an upper limit value at which the occupant does not feel discomfort due to the DS torque amplitude ΔTds, and is set to a constant value in advance, but may be set variably according to the driving conditions such as the change rate of the accelerator opening Acc and the torque change amount Ti0. In this embodiment, the predetermined resetting condition is that the determination in S4 is YES (affirmative), that is, Atdsx>α1. The resetting conditions can be changed as appropriate. For example, the torque change rate Rte may be recalculated when the torque amplitude predicted value Atdsx changes from an increase to a decrease or changes back to an increase.

[0047] In S5, the torque change rate Rte is recalculated in the same manner as in S2, for example, based on the resonance frequency frx at the current time tx. For example, as shown in FIG. 6, when the gear ratio γ starts to change at time t3, and the resonance frequency fr changes with the change in the gear ratio γ, so that Atdsx>α1 at time t4, resulting in a YES determination in S4, the reciprocal (1 / frx) of the resonance frequency frx at time t4 is set as the change time tfx, and the torque change rate Rtex at which the engine torque Te reaches the target engine torque Te1 at time t6, which is the elapsed time tfx from the control start time t2, is calculated. Specifically, the torque change rate Rtex (=ΔTe / Δt) is calculated by dividing the remaining torque ΔTe from the current engine torque Tex to the target engine torque Te1 by the remaining time Δt (=t6-t4=tfx-tax) from the current time t4 to the time t6. Then, the engine 12 is controlled so that the engine torque Te rises at the new rate of change of torque Rtex. Note that the rate of change of torque Rtex can be determined based on the target gear ratio γ1, or the rate of change of torque Rte can be increased or decreased by a fixed amount regardless of the resonance frequency fr. It is not necessarily required to set the rate of change of torque Rte in the same way as S2.

[0048] In S7, it is determined whether the torque change control for changing the engine torque Te to the target engine torque Tetgt has ended, and steps S3 and onwards are repeatedly executed until the torque change control ends. When the torque change control ends, the series of controls are ended and steps S1 and onwards are executed again.

[0049] The solid line in Fig. 6 shows the present embodiment in which the engine torque Te is started up according to the flow chart in Fig. 2, and the torque change rate Rte is changed from Rte0 to Rtex at time t4. The DS torque amplitude ΔTds is maintained relatively small regardless of the change in the gear ratio γ. The dashed line in Fig. 6 shows a comparative example in which the engine torque Te is started up to the target engine torque Te1 with the torque change rate Rte0 at the beginning regardless of the change in the gear ratio γ. Although the engine torque Te can be started up to the target engine torque Te1 at time t5, the DS torque amplitude ΔTds is larger than that of the present embodiment. The dashed line in Fig. 6 shows a conventional example equivalent to the above example in which the torque change rate Rte is set without considering the change in the resonance frequency fr so that the engine torque Te can be started up as quickly as possible while preventing the DS torque amplitude ΔTds from becoming large as in the comparative example. Although the DS torque amplitude ΔTds is not as large as in the comparative example, the start-up completion time is delayed until time t7. For example, when comparing the DS torque amplitude ΔTds when the engine torque Te is raised to about 150 Nm and the DS torque Tds is set to about 500 Nm, the DS torque amplitude ΔTds is about 60 Nm in this embodiment shown by the solid line, whereas it is about 180 Nm in the comparative example shown by the dashed line and about 120 Nm in the conventional example shown by the dotted line. Thus, according to this embodiment, it is possible to significantly reduce the DS torque amplitude ΔTds while maintaining a relatively short rise time.

[0050] As described above, according to the engine torque change control unit 84 of the vehicle 8 of this embodiment, in the process of changing the engine torque Te at the initially set torque change rate Rte0, the torque amplitude prediction value Atdsx, which is a prediction value of the amplitude ΔTds of the torque fluctuation occurring in the DS torque Tds in association with the change in the resonance frequency fr caused by the change in the gear ratio γ of the continuously variable transmission 24, is calculated, and if the torque amplitude prediction value Atdsx changes beyond the allowable value α1, the torque change rate Rte is changed. Therefore, regardless of the change in the resonance frequency fr caused by the change in the gear ratio γ of the continuously variable transmission 24, an increase in the DS torque amplitude ΔTds can be suppressed.

[0051] In addition, the torque amplitude predicted value Atdsx in the case where the change in the engine torque Te is currently stopped is calculated according to equation (1) based on the elapsed time tax after the torque change control is started, the amount of change Tix in the engine torque Te after the torque change control is started, and the resonance frequency frx that changes in accordance with the change in the gear ratio γ of the continuously variable transmission 24. Therefore, it is possible to appropriately predict the increase in the DS torque amplitude ΔTds caused by the change in the resonance frequency fr, and to control the engine torque Te so that the increase in the DS torque amplitude ΔTds is suppressed.

[0052] Furthermore, when starting the torque change control, the initial torque change rate Rte0 is set so that the engine torque Te can be changed to the target engine torque Tetgt in the initial change time tf0, which is the reciprocal of the initial resonance frequency fr0, so that the resonance of the power transmission path, i.e., the DS torque amplitude ΔTds, can be appropriately suppressed.

[0053] Next, another embodiment of the present invention will be described. In the following embodiment, the parts that are substantially the same as those in the above embodiment are given the same reference numerals and detailed description thereof will be omitted.

[0054] Fig. 13 is a flowchart for explaining signal processing executed by the engine torque change control unit 84 instead of Fig. 2. R1, R3, R6, and R7 in Fig. 13 are the same as S1, S3, S6, and S7 in the above embodiment, and R2, R4, and R5 are different from S2, S4, and S5. Fig. 13 relates to control when the engine torque Te is increased in accordance with the depression of the accelerator pedal 93 during tip-in acceleration, etc., and in R2, first, a torque change amount Ti0 when increasing the engine torque Te to the target engine torque Tetgt and an initial resonance frequency fr0 determined according to the gear ratio γ0 of the continuously variable transmission 24 at the start of control are calculated. Then, based on the torque change amount Ti0 and the initial resonance frequency fr0, the initial torque amplitude predicted value Atds0, which is the amplitude of the torque fluctuation predicted to occur in the drive shafts 38L, 38R, is calculated according to the above formula (2) with the rise time ts for increasing the engine torque Te to the target engine torque Tetgt as a variable. The formula (2) is determined based on the theoretical formula (C) of FIG. 12, and the coefficient K2 is determined according to the hardware specifications of the vehicle 8. The coefficient K2 is determined according to the initial resonance frequency fr0.

[0055] Next, from the relationship between the calculated initial torque amplitude prediction value Atds0 and the rise time ts, an initial rise time ts0 at which the initial torque amplitude prediction value Atds0 becomes a predetermined target value β is calculated. FIG. 14 shows an example of the relationship between the initial torque amplitude prediction value Atds0 and the rise time ts. Since the initial torque amplitude prediction value Atds0 becomes minimal at the rise time ts=1 / fr0, the rise time ts at which Atds0=β is shorter than the initial rise time ts0 is set as the initial rise time ts0. The target value β is preset to a constant value so that the driver can feel a predetermined increase in driving force by the DS torque amplitude ΔTds, for example, but may be variably set according to the driving state such as the change rate of the accelerator opening Acc and the torque change amount Ti0. Then, an initial torque change rate Rte0 at which the engine torque Te increases to the target engine torque Tetgt at the initial rise time ts0 is calculated. For example, in the case of FIG. 5 and FIG. 6, the initial torque change rate Rte0 (=Ti0 / ts0) is obtained by using the initial rise time ts0 instead of the initial change time tf0 (=1 / fr0) and dividing the torque change amount Ti0 by the initial rise time ts0.

[0056] By controlling the engine 12 so that the engine torque Te is increased at this initial torque change rate Rte0, it is possible to generate torque fluctuations of a predetermined DS torque amplitude ΔTds equivalent to the target value β while preventing the DS torque amplitude ΔTds, which is the amplitude of the torque (DS torque) Tds of the drive shafts 38R, 38L, from becoming excessive.

[0057] On the other hand, in the process of increasing the engine torque Te at the initial torque change rate Rte0, steps R3 and after are executed, and if the torque amplitude prediction value Atdsx calculated according to the above formula (1) becomes larger than a predetermined allowable value α2, R5 is executed to recalculate the torque change rate Rte. The allowable value α2 is, for example, a value that makes the DS torque amplitude ΔTds considerably larger than the target value β and is larger than the allowable value α1 in the above embodiment, and is set to a constant value in advance, but may be set variably according to the operating conditions such as the change rate of the accelerator opening Acc and the torque change amount Ti0. In this embodiment, the predetermined resetting condition is that the determination in R4 is YES (affirmative), that is, Atdsx>α2.

[0058] In R5, the torque change rate Rte is recalculated in the same manner as in R2, for example, based on the resonance frequency frx at the current time tx. That is, a new torque change rate Rte that can generate a predetermined DS torque amplitude ΔTds corresponding to the target value β is calculated regardless of the change in the resonance frequency fr associated with the change in the gear ratio γ. Specifically, the initial torque amplitude prediction value Atds0 is calculated according to the above formula (2) using the resonance frequency frx at the current time tx instead of the initial resonance frequency fr0, and the rise time tsx at which the initial torque amplitude prediction value Atds0 becomes the predetermined target value β is obtained from the relationship between the calculated initial torque amplitude prediction value Atds0 and the rise time ts. Then, in order that the engine torque Te reaches the target engine torque Tetgt when the elapsed time from the control start point reaches the rise time tsx, the remaining torque ΔTe (Trtgt-Tex) is divided by the remaining time Δt (=tsx-tax) in the same manner as in the above embodiment to obtain the torque change rate Rtex (=ΔTe / Δt), and the engine 12 is controlled so that the engine torque Te rises at the new torque change rate Rtex. Note that the torque change rate Rte does not necessarily have to be set in the same way as R2; for example, the torque change rate Rte may be reduced by a fixed amount regardless of the resonance frequency fr.

[0059] In this embodiment, the same effects as those of the above embodiment can be obtained, such as suppressing an increase in the DS torque amplitude ΔTds by executing R3 to R5, regardless of the change in the resonance frequency fr caused by the change in the speed ratio γ of the continuously variable transmission 24. In addition, in R2, the initial torque amplitude predicted value Atds0 is calculated according to the formula (2) using the rise time ts for increasing the engine torque Te to the target engine torque Tetgt as a variable, and the rise time ts0 at which the initial torque amplitude predicted value Atds0 becomes a predetermined target value β is obtained from the relationship between the initial torque amplitude predicted value Atds0 and the rise time ts, and the initial torque change rate Rte0 is set so that the engine torque Te is increased to the target engine torque Tetgt at the rise time ts0. Therefore, a predetermined DS torque amplitude ΔTds equivalent to the target value β is generated while suppressing the DS torque amplitude ΔTds caused by the change in the engine torque Te from becoming excessive, and the driver can feel the increase in the driving force of the vehicle 8 due to the driver's accelerator operation, etc.

[0060] Although the embodiments of the present invention have been described in detail above with reference to the drawings, these are merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0061] 8: Vehicle 10: Vehicle power transmission device (power transmission path) 12: Engine (driving force source) 20L, 20R: Drive wheels 24: Belt-type continuously variable transmission (continuously variable transmission) 38L, 38R: Drive shaft 80: Electronic control device (vehicle control device) 84: Engine torque change control unit (driving force source torque change control unit) γ: Gear ratio Te: Engine torque (driving force source torque) Tetgt, Te1: Target engine torque (target driving force source torque) Tix: Amount of change in driving force source torque Ti0: Amount of torque change tax: Elapsed time ts: Start-up time ts0: Initial start-up time fr: Resonance frequency frx: Resonance frequency (current resonance frequency) fr0: Initial resonance frequency Rte, Rtex: Torque change rate Rte0: Initial torque change rate (torque change rate) Tds: DS torque ΔTds: DS torque amplitude (amplitude of torque fluctuation) Atdsx: Torque amplitude prediction value Atds0: Initial torque amplitude prediction value α1, α2: Tolerance value (resetting condition) β: Target value

Claims

1. A vehicle having a driving force source and a continuously variable transmission disposed in a power transmission path between the driving force source and a drive wheel, A control device for a vehicle having a driving force source torque change control unit that, when changing a driving force source torque that is a torque of the driving force source, sets a torque change rate based on a resonance frequency of the power transmission path that is determined according to a gear ratio of the continuously variable transmission, and changes the driving force source torque at the torque change rate, The driving force source torque change control unit calculates an amplitude of torque fluctuation predicted to occur in the power transmission path in association with a change in resonance frequency caused by a change in the gear ratio of the continuously variable transmission during the process of changing the driving force source torque at the torque change rate, and changes the torque change rate when the calculated torque amplitude prediction value changes beyond a predetermined reset condition. A vehicle control device comprising:

2. The driving force source torque change control unit sequentially calculates, as the torque amplitude predicted value, an amplitude Atdsx of torque fluctuation predicted to occur in the drive shaft when the change in the driving force source torque is stopped at the current time, according to the following equation (1), based on an elapsed time tax after the start of torque change control for changing the driving force source torque at the torque change rate, an amount of change Tix in the driving force source torque after the start of the torque change control, and a resonance frequency frx that changes in accordance with a change in the gear ratio of the continuously variable transmission: Atdsx=Tix×[K1 / (tax×frx)]×sin(tax×frx) ・・・(1) However, K1 is a coefficient 2. The vehicle control device according to claim 1.

3. The driving force source torque change control unit sets the torque change rate at the beginning of torque change control for changing the driving force source torque at the torque change rate so that the driving force source torque is changed to the target driving force source torque in a time period that is the reciprocal of a resonance frequency of the power transmission path.

3. The vehicle control device according to claim 1 or 2.

4. The driving force source torque change control unit calculates an initial torque amplitude predicted value Atds0, which is the amplitude of torque fluctuation predicted to occur in the drive shaft, according to the following equation (2), using a torque change amount Ti0 when increasing the driving force source torque to the target driving force source torque and an initial resonance frequency fr0, which is the resonance frequency of the power transmission path at the start of control, as a variable, and determines an initial rise time ts0 at which the initial torque amplitude predicted value Atds0 becomes a predetermined target value from the relationship between the calculated initial torque amplitude predicted value Atds0 and the rise time ts, and sets the torque change rate so that the driving force source torque is increased to the target driving force source torque at the initial rise time ts0. Atds0=Ti0×[K2 / (ts×fr0)]× sin (ts×fr0) ・・・(2) However, K2 is a coefficient 3. The vehicle control device according to claim 1 or 2.

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