JPH115460A - Control device for vehicle provided with continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the fore and aft directional vibration of a vehicle by estimating a time point before the speed change concluding time point by a half period of the fore and aft directional vibration of a vehicle to be generated at the time of changing the driving wheel torque, and maintaining the driving wheel torque from a start of the speed change to that time point, and controlling the driving torque to a half of the target torque. SOLUTION: Driving wheel torque Td satisfies a formula Td=TE/GS-TI in a block R of a half period t0/2 of the fore and aft directional vibration of a vehicle. At this stage, engine torque Tm is generated in consideration of the inertia torque T1 to be generated by a change ratio ΔNe (gear shifting speed) of the engine speed Ne, and during the initial time of the speed change, engine speed after a Δt step in a block Q is estimated. The inertia torque T1 due to a change of the rotation of an input shaft is computed, and a required throttle open degree TAfin, which offsets the inertia torque T1, and a speed change duty ratio are output, and the gear shifting speed is controlled so as to obtain the torque T/2 at a half of the final driving wheel torque T at the time of controlling the speed change in the block R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle equipped with a continuously variable transmission, and more particularly to a vehicle speed control for lowering a speed associated with an accelerator opening operation, which suppresses longitudinal vibration of the vehicle at the end of the shift. Related to technology.

[0002]

2. Description of the Related Art Generally, in a shift control of a continuously variable transmission to a low speed side in response to an accelerator opening operation of a vehicle equipped with a continuously variable transmission, a longitudinal vibration of the vehicle is generated due to an increase in torque at the end of the shift. The vehicle front-rear vibration is generated by a sudden change in torque in the vehicle driving direction because the driving wheels are not rigid bodies (spring constant in the torsional direction is infinite).

[0003] In a vehicle with a continuously variable transmission, the total of the engine torque and the inertia torque of the engine and the input shaft system of the continuously variable transmission is determined by the driving wheels while the gear ratio is being changed to a low speed side, such as during rapid acceleration. (Drive shaft)
In order to prevent vehicle longitudinal vibration (drive shaft torsional vibration), it is necessary to control engine torque and inertia torque. Since the inertia torque is determined by the speed change speed, it is necessary to properly control the speed change speed after all.

In view of this point, for example, Japanese Patent Application Laid-Open No. 8-177
In order to suppress the above-mentioned vehicle longitudinal vibration, Japanese Patent Application Laid-Open No. 997-977 discloses that the speed ratio of a continuously variable transmission is controlled so as to cancel the thrust of the torque from a point in time half a cycle before the vehicle longitudinal vibration from the end of the shift. Proposed. That is, according to this control, as shown in FIG. 11, the shift end time Te is predicted as the time when the actual gear ratio intersects with the target gear ratio, while the shift end time Te is generated at the shift end time with the shift to the lower speed side. Then, Ts half a cycle before the predicted vehicle vibration is predicted based on the input torque and the gear ratio. Then, in order to generate vibration in the reverse direction at Ts before the half cycle, the shift control amount is changed from a time Ts (actually, a delay time is added to the half cycle) from the time Ts half cycle before the shift end time Te. By correcting only S, and correcting the speed ratio to a higher speed side as shown by a part A in the figure, the vibration which conventionally oscillated as shown by a graph B becomes like a graph C shown in FIG. Trying to suppress vibration.

[0005]

However, in general, after the accelerator is opened (range To in FIG. 11), the drive shaft is twisted, and the torsional vibration of the vehicle occurs due to the twist (reference D in the drawing). As a result, the drive shaft is twisted at the time Ts half a cycle before the shift end time Te, so that the drive wheel torque is affected by the twist of the drive shaft. There is a problem that even if the shift control amount is corrected as in the publication, the longitudinal vibration of the vehicle at the end of the shift cannot be properly suppressed.

Originally, the drive wheel torque for suppressing the longitudinal vibration of the vehicle must be as shown in the drive wheel torque graph shown in FIG. That is, for the final (target) torque T,
During the half period t0 / 2 of the period t0 of the longitudinal vibration of the vehicle, a torque T / 2, which is half of the final torque T, is applied to the driving wheels, and the torque is shifted stepwise to the final torque T. As a result, it is possible to smoothly shift to the equilibrium state of the final torque T, and the longitudinal vibration of the vehicle can be suppressed.

[0007] However, in the one disclosed in the above publication,
The drive wheel torque is affected by the torsion of the drive shaft, and the time to change the drive wheel torque by correcting the gear ratio does not match the cycle of the vehicle longitudinal vibration, and the torque T / that is half of the final torque
It is difficult to make a step-by-step transition from 2 to the final torque T, and vibration cannot be suppressed quickly.
Further, the controllability of the gear ratio itself at the end of the gear shift is also deteriorated due to the vehicle longitudinal vibration (relative torsion between the tire and the engine) after the accelerator opening operation.

The present invention has been made in view of the above-mentioned conventional problems, and has a continuously variable transmission capable of improving controllability of driving wheel torque and suppressing longitudinal vibration of a vehicle at the end of shifting. It is an object to provide a control device for a vehicle.

[0009]

The invention according to claim 1 is
As shown in FIG. 1 (A), in a control device for a vehicle having a continuously variable transmission and transmitting the output of the continuously variable transmission to driving wheels via a drive shaft, a continuously variable transmission accompanying an accelerator opening operation is provided. In order to suppress vehicle longitudinal vibration at the end of shifting to a low speed side of the transmission, stepless transmission is performed for a half cycle of vehicle longitudinal vibration that occurs when the drive wheel torque changes stepwise from the current torque to the target torque. Means for predicting a point in time immediately before the end of the shift of the engine, a step for preventing the drive wheel torque from changing from the start of shifting of the continuously variable transmission to a point in time before the half cycle, and a target from the point in time before the half cycle. Means for controlling the engine torque so as to attain the engine torque; and a shift speed of the continuously variable transmission such that the drive wheel torque is half of the target torque from the point before the half cycle to the end of the shift. By providing a means for controlling it is obtained by solving the above problems.

According to a second aspect of the present invention, in addition to the first aspect, there is further provided a means for determining whether or not the engine torque at the point in time before the half cycle matches the target engine torque. If the engine rotation speed change rate ΔNe2 at the end of the shift, the engine rotation speed change rate up to the half cycle before this is ΔNe, and the engine rotation speed change rate from the half cycle before the shift end to ΔNeS, ΔNeS = (ΔNe + ΔNe2) / 2, the above-mentioned problem is also solved by changing the engine speed at the speed of the continuously variable transmission so that the drive wheel torque becomes half of the target torque. It was done.

According to a third aspect of the present invention, in the first aspect, there is further provided means for judging whether or not the engine torque at the point in time before the half cycle coincides with the target engine torque. Otherwise, if the target drive wheel torque T 'and the input shaft inertia moment are Iin, and the rate of change in the engine speed from half a cycle before the end of the shift is .DELTA.NeS', .DELTA.NeS '= T' / (2 ×
By changing the engine rotation speed at the speed of Iin), the speed of the continuously variable transmission is controlled so that the drive wheel torque becomes half of the target torque, thereby solving the above-mentioned problem. .

According to the first aspect of the invention, first, a half cycle of the longitudinal vibration of the vehicle generated when the drive wheel torque changes stepwise from the current torque to the target torque is obtained, and the continuously variable transmission is performed. A point in time before the half cycle is predicted from the end point of the gear shift of the machine.

When the shift is started, the engine torque is set to the target engine torque just before the half cycle, so that the drive wheel torque does not change from the start of the shift to the point just before the half cycle.

By controlling the drive wheel torque to be half of the target torque from the point before the half cycle to the end of the shift, the longitudinal vibration of the vehicle can be suppressed.

Hereinafter, this will be described with reference to the drawings.

In FIG. 2, the upper graph shows the driving wheel torque, and the lower graph shows the vehicle longitudinal acceleration. The symbol P0 indicates the end of the gear shift, and the symbol P1 indicates a point in time before the half cycle (t0 / 2) of the vehicle longitudinal vibration.

When the drive wheel torque changes as indicated by a broken line a, the vehicle acceleration changes as indicated by a broken line c, and a vehicle longitudinal vibration occurs.

Therefore, the driving wheel torque is changed to a point P which is a half cycle before the front-rear vibration of the vehicle from the end of the shift as shown by a solid line graph b.
If the torque is changed in a stepwise manner from 1 to the end point P0 of the shift as a torque T / 2 that is half of the target torque T, the vehicle acceleration changes between the two time points P1 and P0 as shown in a graph d.

Here, if the driving wheel torque is maintained at a torque T / 2 which is half of the target torque T as it is, the vehicle acceleration becomes as shown in a graph e, and a vehicle longitudinal vibration occurs. In the present invention, the driving wheel torque is set to the half cycle (t0 /
During the period 2), after the torque is set to a half torque T / 2 of the target torque T, the vehicle is controlled stepwise so that the target torque T is reached at the end of the shift P0. The target torque T is maintained in an equilibrium state, and vehicle longitudinal vibration is suppressed.

Further, the invention according to claim 4 includes a continuously variable transmission as shown in FIG. 1B, and transmits the output of the continuously variable transmission to the drive wheels via a drive shaft. Means for predicting a point in time when there is no torsion of the drive shaft after the accelerator opening operation, in order to suppress longitudinal vibration of the vehicle at the end of shifting to a low speed side of the continuously variable transmission due to the accelerator opening operation. And the drive wheel torque is maintained at the target torque until a half cycle of the vehicle longitudinal vibration that occurs when the drive wheel torque changes stepwise from the torque at the time to the target torque from the time when the drive shaft is not twisted. Means for controlling the shift speed of the continuously variable transmission so that the torque becomes half of the torque, and after the half cycle has elapsed, the drive wheel torque becomes the target torque.
Similarly, the object has been achieved.

According to the first aspect of the present invention, as described above, prior to changing the driving wheel torque stepwise, the engine torque is controlled so that the driving wheel torque does not change (as a pre-control). The above-mentioned control is executed in a state in which the drive shaft is not twisted. However, the invention according to claim 4 is particularly effective when such pre-control is not performed, that is, when the drive shaft is twisted. This corresponds to the case where

According to the fourth aspect of the present invention, the time when the drive shaft is not twisted (instead of preventing the drive shaft from being twisted) is predicted, and from that time, as described above, the drive wheels are driven. The torque is controlled stepwise. By doing so, the longitudinal vibration of the vehicle can be suppressed.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a block diagram schematically showing a control device for a vehicle having a continuously variable transmission to which the present invention is applied.

In FIG. 3, a crankshaft 12 of the engine 10 is connected to an input shaft 18 of a belt-type continuously variable transmission (CVT) 16 via a starting clutch 14. CV
The output shaft 20 of T16 is connected to a drive shaft of the vehicle via a differential gear device or the like (not shown). Thereby, the torque of the engine 10 is transmitted to the drive wheels.

The input shaft 18 and the output shaft 2 of the CVT 16
At 0, variable pulleys 22 and 24 having variable effective diameters are provided. A transmission belt 26 is wound between these variable pulleys 22 and 24. Variable pulley 22
And 24 are provided on the fixed rotating bodies 28 and 30 fixed to the input shaft 18 and the output shaft 20, and are provided on the input shaft 18 and the output shaft 20 so as to be movable in the axial direction and relatively non-rotatable in the rotating direction. The movable rotators 32 and 34 are provided.

The movable rotators 32 and 34 are moved in the axial direction by hydraulic pressure, and as a result, V is formed between the fixed rotators 28 and 30 and the movable rotators 32 and 34.
The groove width, that is, the engagement diameter of the transmission belt 26 is changed.

Rotation speed sensors 36 and 38 are provided to detect the rotation speeds of the input shaft 18 and the output shaft 20, respectively, and these detection signals are sent to an electronic control unit (EC).
U) 40. The ECU 40 calculates C based on this signal.
The gear ratio of the VT 16 is calculated.

An intake pipe of the engine 10 is provided with an air amount sensor 42 for detecting an intake air amount. A rotation sensor 44 for detecting the engine speed is provided near the crankshaft 12. The ECU 40 optimally controls the fuel injection amount and the ignition timing according to the intake air amount and the engine speed.

An accelerator sensor 48 for detecting the accelerator opening is provided near the accelerator pedal 46. E
The CU 40 controls the intake air through the throttle actuator 50 based on the accelerator opening obtained by the accelerator sensor 48, the vehicle speed obtained by the rotation speed sensor 38, and the engine rotation speed obtained by the rotation speed sensor 44 so that, for example, the fuel efficiency is optimized. Control the amount.

The shift lever 52 provided near the driver's seat is provided with a shift sensor 54 for detecting the operating position.

The ECU 40 determines the starting clutch 14 and the CVT 16 based on information such as the drive range detected by the shift sensor 54, the vehicle speed, and the accelerator opening.
Control the transmission gear ratio.

Next, as a first embodiment of the present invention, an integrated control of the engine torque and the shift speed of the CVT 16 will be described. This corresponds to control in the case of rapid acceleration, for example, such that the shift speed of the CVT 16 is initially maximum.

FIG. 4 is a flowchart showing the shift and engine torque control. Hereinafter, description will be given along this flowchart.

FIG. 5 shows the accelerator opening Acc, the engine speed Ne, the input shaft inertia torque TI,
7 shows changes in the throttle opening TAm, the engine torque Tm, and the drive wheel torque Td.

In step 100, it is determined whether or not the starting clutch is completely engaged (on or not). If the starting clutch is not on, a starting clutch off-time control process is performed. When the starting clutch is ON, in the next step 102, the accelerator opening change ΔACC is set to a predetermined value α.
It is determined whether it is greater. As shown in FIG. 5, when the accelerator opening change .DELTA.Acc is larger than the predetermined value .alpha., The flag frag1 indicating rapid acceleration is set to 1 in the next step 104.
If the accelerator opening change ΔAcc is smaller than the predetermined value α, it is determined in step 106 whether the flag frag1 is 1. Here, when the flag frag1 is not 1, the normal shift control process is performed. If the flag frag1 is 1, the process proceeds to step 108.

At step 108, it is determined whether or not a flag frag2 indicating whether or not the vibration suppression control is being performed is "1". If the flag frag2 is 1, the process proceeds to step 122 to perform the vibration suppression control. If the flag frag2 is not 1, in the next step 110, the target engine speed Ne
0 and the actual engine speed Ne (Ne0−N
When e) becomes equal to or less than the threshold value, it is determined whether or not Nes is equal to or less than a threshold value Nes at which the vibration suppression control should be started. If the difference between the engine rotation speeds is equal to or smaller than the threshold NeS, the process proceeds to step 122 to perform the vibration suppression control.

The difference between the engine rotation speeds (Ne0-N
If e) is larger than the threshold value NeS, the routine proceeds to the next step 112, where the duty ratio Duty required for the hydraulic control for shifting is set to the target engine speed Ne0 and the actual engine speed by the following equation (1). It is calculated as a function of the speed Ne.

Duty = f1 (Ne0, Ne) (1) The shift duty ratio Duty represents, for example, the duty ratio of a shift solenoid.

Next, at step 114, the final throttle opening TAfin added with the inertia torque is calculated by the following equations (2) to (7).

First, according to the following equation (2), the engine rotation speed NeΔt after the Δt step is predicted from the current engine rotation speed Ne and the duty ratio Duty calculated above.
Is calculated.

NeΔt = f 2 (Duty, Ne) (2)

Next, a predicted shift speed (rate of change in engine speed) ΔNe is calculated from the current engine speed Ne and the engine speed NeΔt after Δt steps predicted from the duty ratio Duty according to the equation (3). .

ΔNe = (NeΔt−Ne) / Δt (3)

Next, using the predicted shift speed ΔNe and the input shaft inertia moment Iin, the inertia torque TI due to the input shaft rotation change is calculated by the following equation (4).

TI = f 3 (Iin, ΔNe) (4)

Next, the engine torque Tm before the gear shift control is calculated from the throttle opening TAm before the gear shift control and the actual engine rotational speed Ne by the equation (5).

Tm = f4 (TAm, Ne) (5)

Next, the engine torque T before the shift control is performed.
The required torque Tfin for canceling the inertia torque TI is calculated by adding the inertia torque TI due to the change in the rotation of the input shaft to m as shown in the following equation (6).

Tfin = Tm + TI (6)

Finally, using the required torque Tfin for canceling the inertia torque TI and the current engine speed Ne, the required throttle opening for canceling the inertia torque TI is calculated by the following equation (7). Calculate TAfin.

TAfin = f5 (Tfin, Ne) (7)

In step 116, the required throttle opening TAfin for canceling the inertia torque TI just calculated.
And the shift duty ratio Duty calculated previously is output.

In FIG. 5, in the section Q from the shift start tv to the shift end te to a half cycle before the vehicle longitudinal vibration ts, the shift control is performed by the required throttle opening TAfin and the shift duty ratio Duty. In the section Q, the values at which the throttle opening degree TAm and the engine torque Tm are every moment are TAfin and Tfin, respectively.

Next, in step 118, (8) to
The threshold NeS for shifting to the vehicle longitudinal vibration suppression control is calculated by the equation (12).

First, the target throttle opening TAS required from the accelerator opening Acc is obtained from the required throttle opening TAfin for canceling the inertia torque by the following equation (8).

TAS = f6 (TAfin) (8)

Next, the target engine torque TE / GS is calculated by the equation (9) using the target throttle opening TAS and the target engine rotation speed Ne0 required from the accelerator opening Acc.

TE / GS = f7 (TAS, Ne0) (9)

Next, according to the equation (10), the half cycle t0 of the longitudinal vibration of the vehicle is obtained by using the gear ratio γ, the target engine rotational speed Ne0 and the target engine torque TE / GS at the time when the target throttle opening TAS is reached. / 2 is calculated.

T0 / 2 = f8 (γ, TE / GS) (10) Here, the target engine torque TE at the time point ts just before the shift end time by the half cycle t0 / 2 of the vehicle longitudinal vibration.
/ GS and the actual engine torque TnS at that time are determined.

If they match (normal case), the predicted shift speed (the rate of change in engine speed) ΔNe after the Δt step and the engine speed Ne after the end of the shift are calculated by equation (11). By taking the average of the slope (shift speed) ΔNe2 of the graph (straight line) of the graph, the shift speed (engine rotation speed) at which the driving wheel torque T becomes half the torque when the target engine torque TE / GS is finally reached is reached. (Change rate) ΔNeS is calculated.

ΔNe S = (ΔNe + ΔNe2) / 2 (11)

By the above determination, as shown by the broken line in FIG. 5, a time t before a half cycle at which the longitudinal vibration of the vehicle occurs.
In s, when the target engine torque TE / GS does not match the actual engine torque TmS, the new torque at that time (ts) becomes half of the final drive wheel torque T 'according to the equation (12). Shift speed ΔN
eS 'is calculated using the input shaft inertia moment Iin.

ΔNe S ′ = T ′ / (2 × Iin) (12)

By the way, a new (final) drive wheel torque T 'is calculated by a method of calculating the drive wheel torque Td1 in the uncontrolled (normal running) state and the wheel rotation at the vehicle speed (engine speed). When the speed is n1, the new target engine speed Ne at te at the end of the shift is
It can be calculated as in the following equation (13) using 0 ′.

T ′ = Td 1 × n 1 / Ne 0 ′ (13)

In any case, the point is that the drive wheel torque Td is half of the final target torques T and T 'from the time ts just before the half cycle to the shift end time te.
Thus, the speed of the continuously variable transmission (the rate of change of the engine speed) △ NeS, △ NeS 'is controlled so as to be / 2.

In this way, at the time point ts just before the shift end time te for the half cycle of the longitudinal vibration of the vehicle, whether the target engine torque TE / GS at the time point ts just before the half cycle is equal to the actual engine torque Tms. By using the corresponding equations (11) and (12),
Vibration suppression control can be realized with high accuracy.

Hereinafter, in describing the embodiments of the present invention,
At the time ts before the half cycle, the target engine torque T
The state in which E / GS and the actual engine torque Tms match will be described. If they do not match, the target engine speed is changed from Ne0 to Ne0 as shown in FIG.
', And the speed change speeds are ΔNe 2 → ΔNe 2' and ΔNe, respectively.
The same description is obtained by replacing the threshold value of S → ΔNeS ′ with NeS → NeS ′ and the driving wheel torque T → T ′, so that the description is omitted here.

In the graph of the engine rotation speed Ne in FIG. 5, the slope of the tangent at each point in the section Q is the shift speed ΔNe at each time point, the slope of the linear portion in the section R is the shift speed ΔNeS, The inclination of the subsequent straight line portion is the shift speed ΔNe2. Note that the shift speed ΔN
e2 is determined by a map from the accelerator opening Acc.
In FIG. 5, the target engine rotation speed Ne0 has been reached at the end of the shift te, and the shift speed .DELTA.Ne2 = 0. Therefore, in this case, the shift speed .DELTA.NeS is calculated from the engine rotational speed Ne at the end of the section Q according to the above equation (11).
Of the tangent of the graph (engine rotation speed change rate) ΔN
e.

Finally, the threshold NeS for shifting to the vehicle longitudinal vibration suppression control is calculated by the following equation (14).

NeS = ΔNeS × t0 / 2 (14)

Thus, the half cycle t0 / 2 of the vehicle longitudinal vibration
Is used to calculate the threshold value NeS, so that the difference Ne0 between the target engine speed Ne0 and the actual engine speed Ne0 is calculated.
By comparing -Ne with this threshold value, it is possible to detect the timing (ts in FIG. 5) just before the half cycle.

Next, at step 120, the flag frag
The routine exits from this routine by setting 2 to 0.

When it is determined in step 108 that the vibration suppression control flag frag2 is 1, and in step 110, the difference between the target engine speed Ne0 and the current engine speed Ne is equal to or smaller than a threshold NeS (Ne0-
If it is determined that Ne ≦ NeS), the process proceeds to step 122 to perform vehicle longitudinal vibration suppression control.

At step 122, it is determined whether or not the engine speed Ne is equal to the target engine speed Ne0. If the engine speed Ne has already reached the target engine speed Ne0, the flag frag1 is set at step 124. When the value is set to 0, the vibration suppression control is terminated, and the routine exits.

If the engine speed has not reached the target engine speed, in the next step 126, the shift duty ratio Duty for vibration suppression control is set to
It is calculated from the shift speed .DELTA.NeS, which is half the driving wheel torque T when the final engine torque TE / GS is reached, and the actual engine rotational speed Ne according to equation (15).

Duty = f 9 (Ne, ΔNe S) (15)

In the next step 128, the vibration suppression control flag frag2 is set to 1, and in step 130, the shift duty ratio Duty calculated above is output, and the vibration suppression control is performed.

That is, the half cycle t0 /
2, the drive wheel torque Td is equal to the target torque T.
The gear ratio γ is controlled so as to be half the torque T / 2. Note that the drive wheel torque Td = TE / GS-TI.

At this time, conventionally, the engine torque Tm is not controlled during the initial stage of the gear shift (control of the gear ratio to a lower speed side). Therefore, if the engine torque Tm is larger than the inertia torque TI, the drive is started. A step-like torque was applied to the wheels, causing vehicle longitudinal vibration.

On the other hand, as described above, in the present embodiment, the engine torque Tm is generated in consideration of the inertia torque TI generated by the change rate ΔNe (shift speed) of the engine rotation speed Ne. Drive wheel torque Td
The control in steps 114 and 116 in FIG. 4 is performed in the section Q of FIG. 5 so that there is no change in the transmission speed. By controlling, the longitudinal vibration of the vehicle is suppressed.

Next, a second embodiment of the present invention will be described.

In this embodiment, too, control is performed to suppress the longitudinal vibration of the vehicle that occurs in the shift control to the low speed side due to the accelerator opening operation. That is, when the engine torque rises at the time of opening the accelerator, if the torque is larger than the inertia torque, vehicle longitudinal vibration occurs. However, in this embodiment, when the drive shaft between the transmission and the wheels is not twisted (equilibrium state). Furthermore, during a half cycle of the vehicle longitudinal vibration, the shift speed is controlled so that the torque is half of the final drive wheel torque, so that the vehicle longitudinal vibration is quickly suppressed.

FIGS. 6 and 8 show flowcharts of the shift control process of this embodiment, and FIG. 9 shows the control characteristics.

FIG. 6 is a flowchart showing a process for determining vehicle longitudinal vibration.

First, at step 200, the engine rotational speed change rate ΔNe1 predicted for the shift duty ratio Duty and the shift ratio γ is calculated by the following equation (16).

ΔNe1 = f11 (Duty, γ) (16)

The current engine speed Ne and Δt
The next (1)
The actual engine speed change rate ΔNe is calculated by equation (7).

ΔNe = (Ne−Neold) / Δt (17)

In the next step 202,
It is determined whether or not the absolute value of the difference between the predicted engine speed change rate ΔNe1 and the actual engine speed change rate ΔNe is equal to or larger than a predetermined value β (| ΔNe1-ΔNe | ≧ β).
If this difference is smaller than the predetermined value β, the routine immediately exits this routine.

If the difference is larger than the predetermined value β, it is determined that vibration is occurring, and the next step 204
, The actual engine speed change rate ΔNe is compared with the previous engine speed change rate ΔNeold to determine whether the engine speed change rate is increasing or decreasing. The current engine speed change rate ΔNe is the previous engine speed change rate ΔNe
If it is larger than old, it is determined that the torsion is on the side where the rate of change of the engine speed increases, and in step 206,
The current engine speed change rate ΔNe is set to the maximum engine speed change rate ΔNemax, the value of the timer TIMER indicating the current time is set to time tmax, and a flag frag3 indicating that the engine speed change rate is increasing is set. Let it be 1.

If it is determined in step 204 that the current engine speed change rate ΔNe is equal to or less than the previous engine speed change rate ΔNeold, it is determined that there is a twist on the engine speed change rate decreasing side, and the next step. At 208, it is determined whether or not the flag frag3 is 1. Flag frag3
Is not 1, in the next step 210, the current engine rotation speed change rate ΔNe is set as the engine rotation speed change rate minimum ΔNemin, and the timer T indicating the current time is set.
The value of IMER is set to time tmin, and the flag frag3 is set to 0.

Also, in the judgment in step 208, the flag
If frag3 is 1, in step 212, a time without twist (time t in FIG. 9) is predicted. Step 20
8 is the time when the flag frag3 is first determined to be 1 in FIG.
Is the time at which the rate of change of the engine rotation speed changes from increase to decrease, and the time at which the timer TIMER is just at tmax. From the following equation (18), the difference ts between time t and time tmax, which is predicted to have no twist, is determined. This is represented by a timer indicating the current time as shown in equation (19).
By adding to TIMER, a time t without twist is predicted as shown in FIG.

TS = (tmax−tmin) / 2 (18) t = TIMER + ts (19)

In step 214, the flag frag4 indicating that the balance state and the vibration suppression control are being performed is set to 1.

FIG. 8 is a flowchart showing the flow of processing for actually performing the vibration suppression control.

Since the state without torsion is short, the flowchart of FIG. 8 is a 1 msec routine, in which it is determined every 1 msec whether or not the vibration suppression control is being performed so that the timing is not missed. On the other hand, the determination routine of FIG. 6 may be 1 msec, but may be a little later.

FIG. 9 shows how the engine speed Ne and the like change due to the vibration suppression control.

First, in step 300, it is determined whether or not the flag frag4 indicating the equilibrium state and the vibration suppression control is 1 is set. When the flag frag4 is not 1, the routine exits immediately. If the flag frag4 is 1, in the next step 302, a timer TIMER indicating the current time is set.
Is larger than the time t at which it is predicted that there is no twist. If the time is less than the time t at which no torsion is predicted, it is determined in the next step 304 whether or not the timer TIMER is equal to the time t at which no torsion is predicted. If not, the routine is immediately executed. Exit.

In step 304, the timer TIMER
Coincides with the time t at which it is predicted that there is no twist,
In the next step 306, the above (10), (11)
The shift speed .DELTA.NeS at which the drive wheel torque T becomes half when the half cycle t0 / 2 of the vehicle longitudinal vibration and the final engine torque TE / GS is reached is calculated by the following equations, respectively. An engine speed Ne1 which is a tentative target value at the time of ending the vehicle longitudinal vibration suppression control is calculated.

Ne1 = Ne2 + ΔNeS × t0 / 2 (20) Here, Ne2 is the engine speed at the start of the vehicle longitudinal vibration suppression control (see FIG. 9).

Next, at step 308, the (1)
The shift duty ratio Duty of the continuously variable transmission for controlling the target engine rotational speed change rate .DELTA.NeS is calculated by the equation (5), and as shown in FIG. 9, during the half cycle t0 / 2, the driving wheel torque becomes the target torque. And the engine rotation speed change rate ΔNe becomes the target engine rotation speed change rate ΔNe.
It is controlled to be NeS.

In the determination of step 302, the timer TIME
When the value of R is greater than the time t at which it is predicted that there is no twist, the routine proceeds to step 310, where the actual engine speed Ne is higher than the engine speed Ne1 for ending the vehicle longitudinal vibration suppression control. Judge. as a result,
If the actual engine rotation speed Ne is lower than the engine rotation speed Ne1 for ending the vibration suppression control, the process proceeds to step 308 to continue the control. When the actual engine rotation speed Ne reaches the engine rotation speed Ne1 for ending the vibration suppression control (half cycle t0 / 2 has elapsed), the routine proceeds to step 312, where the final target engine rotation speed is reached. It is determined whether or not Ne0 has been reached.

As a result, if the final target engine speed Ne0 has been reached, the flag frag4 during vibration suppression control is set to 0 in step 314, and the routine exits. If the final target engine rotation speed Ne0 has not yet been reached, in step 316, the next (2)
According to the equation (1), the transmission duty ratio Dut for controlling the target engine rotation speed change rate ΔNeS based on the actual engine rotation speed Ne and the engine rotation speed change rate ΔNe2 for obtaining the final target engine rotation speed Ne0.
Calculate y.

Duty = f12 (Ne, ΔNe2) (21)

In the example shown in FIG. 9, the tentative target engine speed Ne1 at the end of the gear shift te has not reached the final target engine speed Ne0, and the engine speed change rate ΔNe2 is not zero. Therefore, even after a half period t0 / 2 has elapsed, the control is performed with the shift duty ratio Duty just obtained.
As a result, the graph of the drive wheel torque Td is not horizontal as shown by the symbol TS, but is at the upper right.

The broken line graph in FIG. 9 shows the conventional control. Conventionally, even if the control is started at a point in time half a cycle before and after the vehicle longitudinal vibration from the point at which the target engine rotational speed is reached, it is not known at this point in time the state of the vehicle longitudinal vibration (twist). In this state, since a reaction force due to torsion or a forward torque is applied to the drive wheels, the drive wheel torque cannot be controlled only by the gear ratio, and the longitudinal vibration of the vehicle cannot be suppressed.

On the other hand, in the present embodiment, since the drive shaft of the vehicle promotes an equilibrium state (a state in which there is no torsion) and vibration suppression control is performed, when the vehicle longitudinal vibration does not occur as in the first embodiment. The control is performed in the same state as described above, the torque applied to the drive wheels can be controlled by the shift control, and the longitudinal vibration of the vehicle can be suppressed.

The occurrence of the vehicle longitudinal vibration in the initial stage of the accelerator opening operation indicates the undulation of the engine rotational speed as shown in FIG. 10, and therefore, the actual gear ratio or the actual gear ratio with respect to the gearshift signal (duty signal). The determination can be made by detecting whether the engine rotation speed is controlled as usual.

[0112]

As described above, according to the first aspect of the present invention, when controlling the shift speed, the drive wheels are prevented from being twisted from a predetermined time, and according to the second aspect of the present invention,
Improve controllability of drive wheel torque by starting control to reduce drive wheel torque to half of target torque during the half-cycle of vehicle longitudinal vibration from the point where there is no torsion of drive wheels during shift speed control. As a result, vehicle longitudinal vibration can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is an explanatory view showing the principle of vehicle longitudinal vibration suppression according to the present invention.

FIG. 3 is a schematic configuration diagram showing a control device for a vehicle including a continuously variable transmission to which the present invention is applied;

FIG. 4 is a flowchart illustrating control according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a control result according to the first embodiment;

FIG. 6 is a flowchart illustrating a vehicle longitudinal vibration determination process according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a method for predicting a time when the drive shaft has no twist in the second embodiment.

FIG. 8 is a flowchart illustrating vehicle longitudinal vibration suppression control according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a result of control according to the second embodiment in comparison with a conventional example.

FIG. 10 is an explanatory diagram showing a method of determining occurrence of longitudinal vibration of a vehicle at the beginning of an accelerator opening operation.

FIG. 11 is a diagram showing a conventional vehicle longitudinal vibration suppressing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Engine 12 ... Crankshaft 14 ... Starting clutch 16 ... Belt-type continuously variable transmission (CVT) 18 ... Input shaft 20 ... Output shaft 22, 24 ... Variable pulley 26 ... Transmission belt

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16H 59:48 63:06

Claims (4)

[Claims] 1. A control device for a vehicle, comprising: a continuously variable transmission for transmitting an output of the continuously variable transmission to driving wheels via a drive shaft, wherein a shift of the continuously variable transmission to a low speed side in response to an accelerator opening operation. In order to suppress the longitudinal vibration of the vehicle at the time of the termination, the half-cycle of the longitudinal vibration of the vehicle that occurs when the drive wheel torque changes stepwise from the current torque to the target torque is before the end of the shift of the continuously variable transmission. Means for predicting the time point of the engine, and controlling the engine torque so that the drive wheel torque does not change from the start of the shift of the continuously variable transmission to the point in time before the half cycle and the target engine torque from the point in time before the half cycle. Means for controlling the transmission speed of the continuously variable transmission such that the drive wheel torque is half of the target torque from the point in time before the half cycle to the point in time of the end of the shift, A control device for a vehicle equipped with a continuously variable transmission, comprising: 2. The apparatus according to claim 1, further comprising means for judging whether or not the engine torque at the point in time before the half cycle matches the target engine torque. Assuming that the rate of change of the engine speed at the end of the cycle is ΔNe2, the rate of change of the engine speed from the half cycle before the cycle is ΔNe, and the rate of change of the engine speed from the half cycle to the end of the shift is ΔNeS, ΔNeS = (ΔNe + ΔNe2) / The speed of the continuously variable transmission is controlled such that the drive wheel torque is half of the target torque by changing the engine rotation speed at the speed of 2. Control device. 3. The apparatus according to claim 1, further comprising means for judging whether or not the engine torque at the point in time before the half cycle matches the target engine torque. Assuming that the driving wheel torque T 'and the input shaft inertia moment are Iin, and the rate of change of the engine rotational speed from this half cycle to the end of the shift is .DELTA.NeS', the speed is .DELTA.NeS '= T' / (2.times.Iin). A control device for a vehicle equipped with a continuously variable transmission, wherein a shift speed of a continuously variable transmission is controlled such that the drive wheel torque is half of a target torque by changing an engine rotation speed. 4. A control device for a vehicle having a continuously variable transmission and transmitting an output of the continuously variable transmission to drive wheels via a drive shaft, wherein the continuously variable transmission is shifted to a lower speed side in response to an accelerator opening operation. Means for predicting the time when the drive shaft is not twisted after the accelerator opening operation, in order to suppress the vehicle longitudinal vibration at the time of termination, Until the half cycle of the vehicle longitudinal vibration that occurs when the torque changes stepwise to the target torque elapses,
Means for controlling the speed of the continuously variable transmission so that the driving wheel torque becomes half of the target torque, and after the lapse of the half cycle, the driving wheel torque becomes the target torque; A control device for a vehicle equipped with a continuously variable transmission, comprising: