JPH11294573A - Control unit of vehicle equipped with continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothen a transition to feedback control for maintaining a transmission gear ratio, in succession to control over a shift speed for controlling the longitudinal vibrations of a vehicle, to the target value. SOLUTION: In this control unit of a vehicle equipped with a continuously variable transmission which shifts at a shift speed preset according to a shift request, setting it to the shift speed for controlling the longitudinal vibrations of the vehicle at a specified point of time before reaching the target transmission gear ratio and, after shifting at the shift speed for the longitudinal vibrations of the vehicle, setting it the target transmission gear ratio by feedback control, it is equipped with measures (steps 3 and 6) predicting the shift speed at a point of starting time of the said feedback control, and other means (steps 4 and 7) calculating the shift speed for controlling the longitudinal vibrations of the vehicle on the basis of the predicted shift speed and another shift speed just before setting the shift speed for controlling the longitudinal vibrations of the vehicle, respectively.

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 provided with a continuously variable transmission capable of continuously changing a gear ratio, and more particularly, to suppressing a longitudinal vibration of the vehicle which is expected to occur at the end of a shift. The present invention relates to a device for performing control.

[0002]

2. Description of the Related Art Recently, a continuously variable transmission has been used as a transmission for a vehicle. This type of continuously variable transmission is configured to continuously change the gear ratio by changing the groove width between the input side pulley and the output side pulley around which the belt is wound, that is, the belt winding radius. Or by inclining the power rollers sandwiched between the input side disk and the output side disk each having a toroidal surface to change the radius of the contact position of the power roller with each disk, thereby changing the gear ratio. It is configured to change continuously. The gear ratio is determined by, for example, an accelerator pedal depression angle (accelerator opening) signal indicating a driver's output request, an output request signal from a cruise control that maintains the vehicle speed at a constant vehicle speed, and a vehicle speed. It is controlled based on the running state of the vehicle.

Therefore, when there is an acceleration request due to depression of an accelerator pedal or the like, the gear ratio is controlled to be increased. This is because, in a belt-type continuously variable transmission, the width of the belt on the input side pulley is increased to gradually reduce the winding radius of the belt, and at the same time, the width of the output side pulley is reduced to reduce the belt winding radius. Is performed by increasing. Further, the gear ratio finally set at that time is determined based on the target rotation speed of the prime mover, the vehicle speed, and the like which are determined based on the degree of the output increase request. In the case of such a so-called power-on downshift, inevitable torsion occurs in a power transmission system such as a propeller shaft, and the number of revolutions increases at a predetermined rate. At the end of the reached shift, the torsional torque or the inertia torque may cause a drive torque thrust (overshoot) and a longitudinal vibration (shake) of the vehicle.

In order to prevent or suppress the longitudinal vibration of the vehicle at the end of the shift, it is effective to change the change in the driving torque associated with the shift immediately before the end of the shift. No. 8-177997. The device described in this publication is configured to temporarily reduce the speed ratio immediately before the end of the speed change for increasing the speed ratio. That is, in this device, the time when the speed ratio reaches the target speed ratio and the half cycle of the vehicle longitudinal vibration at the target speed ratio are predicted, and the correction start time of the speed ratio is determined based on the prediction result. At this point, the gear ratio is corrected to the higher vehicle speed side to change the tendency of the drive torque to increase.

[0005]

The control for suppressing the longitudinal vibration of the vehicle is performed by changing the gear ratio and temporarily changing the shift speed as described above.
For example, it is executed by outputting a control value so as to reach a predetermined target shift speed. On the other hand, during normal running of a vehicle equipped with a continuously variable transmission other than during gear shifting, the gear ratio is usually maintained at a predetermined value by feedback control.

[0006] As described above, since the control form is different between the control of the shift speed for suppressing the vehicle longitudinal vibration and the control for maintaining the gear ratio after the shift, the control is not performed at the time of the shift. When appropriate, the torque may fluctuate, resulting in shock or vibration of the vehicle body. That is, the shift speed or the engine speed associated with the shift immediately before shifting to the feedback control has been subjected to control for suppressing vehicle body longitudinal vibration, and at the start of feedback control, is based on data affected by the control. Thus, feedback control of the gear ratio is performed. On the other hand, at the same time as the feedback control is started, that is, at the time when the control is shifted from the vehicle longitudinal vibration suppression control to the control for maintaining the gear ratio, the control of the shift speed or the engine speed associated with the shift is released. Therefore, the feedback data for maintaining the gear ratio may change suddenly temporarily. For this reason, the control value for maintaining the gear ratio temporarily fluctuates, and as a result, there is a possibility that the driving torque changes to cause a shock or a vehicle vibration.

The present invention has been made in view of the above circumstances, and smoothly shifts from control for suppressing longitudinal vibration of a vehicle at the end of a gear shift to feedback control for maintaining a gear ratio to prevent shock and vibration. It is an object of the present invention to provide a control device that can perform the control.

[0008]

In order to achieve the above object, the invention described in claim 1 shifts a gear at a predetermined shift speed in response to a shift request and reaches a target gear ratio before reaching a target gear ratio. Control of a vehicle having a continuously variable transmission that sets a shift speed for suppressing vehicle longitudinal vibration at a predetermined point in time, shifts at a shift speed for vehicle longitudinal vibration, and sets a target gear ratio by feedback control An apparatus for predicting a shift speed at the start of the feedback control, and the vehicle longitudinal vibration suppression based on the predicted shift speed and a shift speed immediately before setting a shift speed for vehicle longitudinal vibration suppression. Means for calculating a shift speed for the vehicle.

Therefore, according to the first aspect of the present invention, the inertia torque based on the newly set shift speed is not generated by the overshoot of the output torque due to the inertia torque at the time of shifting to the feedback control and the feedback control by the rotational speed deviation. Therefore, the process smoothly shifts to the feedback control, and the disturbance of the control and the shock or vibration caused by the disturbance are prevented.

According to a second aspect of the present invention, the speed is changed at a predetermined speed in response to a speed change request, and at a predetermined time before reaching a target speed ratio, the speed is set to a speed for suppressing vehicle longitudinal vibration. In a control device for a vehicle having a continuously variable transmission that sets a target gear ratio by feedback control after shifting at a shift speed for vehicle longitudinal vibration, a period for setting a shift speed for suppressing the vehicle longitudinal vibration. And means for controlling the shift speed to substantially zero between the time when the feedback control is started and the time when the feedback control is started.

Therefore, according to the second aspect of the present invention, the shift progresses at a shift speed for suppressing the vehicle longitudinal vibration, and after the vehicle longitudinal vibration suppression control ends, the gear ratio is maintained at a constant value. Since the feedback control is executed at the time of starting the feedback control, the fluctuation of the rotation speed such as the longitudinal vibration of the vehicle is suppressed, so that there is no disturbance factor to the feedback control, and the control can be smoothly shifted to the feedback control.

Further, according to a third aspect of the present invention, the vehicle is shifted at a predetermined speed in response to a speed change request, and at a predetermined time before reaching a target speed ratio, the speed is set to a speed for suppressing vehicle longitudinal vibration. After shifting at the shift speed for longitudinal vibration,
In a control device for a vehicle including a continuously variable transmission that sets a target gear ratio by feedback control, at least a gear speed for suppressing the vehicle longitudinal vibration is added to a gear speed by feedforward control and a gear speed by feedback control. Means for controlling the shift speed, and means for limiting the upper limit value of the shift speed by the feedback control to a value smaller than the shift speed for suppressing vehicle longitudinal vibration at the predetermined time. is there.

Therefore, according to the third aspect of the present invention, when the speed changes and the input speed to the continuously variable transmission approaches the target speed, the speed change by the feedforward control becomes substantially zero, and the speed change by the feedback control is performed. Only for speed. Thereafter, since the upper limit value of the shift speed by the feedback control is small, the control gain is temporarily maintained at a constant value, and the shift speed gradually decreases as the input speed further approaches the target speed. That is, when shifting to the feedback control, the shift speed is temporarily maintained at a constant value not depending on the vehicle longitudinal vibration suppression control, so that the shift to the feedback control can be smoothly performed without being affected by inertia torque or the like. .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on specific examples. First, an example of a power transmission system of a vehicle to which the present invention is applied will be described. In FIG. 7, an output shaft 2 of a prime mover 1 is connected to a transmission 3. Here, the prime mover 1 includes various power sources that can be used for a vehicle, such as an internal combustion engine such as a gasoline engine or a diesel engine, or an electric motor such as a motor, or a device combining the internal combustion engine and the electric motor. In the following description, the prime mover 1
An example in which an engine is adopted will be described.

The engine 1 is configured to be electrically controllable, and is provided with an electronic control unit (ECU) 4 mainly composed of a microcomputer for the control. The control device 4 is configured to control at least the output of the engine 1, and an output request signal such as an output shaft rotation speed Ne and an accelerator opening Acc is input as data for the control. This output request signal is a signal for increasing / decreasing the output of the engine 1, and is an accelerator pedal (not shown) operated by the driver.
In the case of the engine 1 provided with an electronic throttle valve in addition to the operation amount signal Acc of the first embodiment, an opening control signal of the electronic throttle valve, a cruise control system (not shown) for maintaining the vehicle speed at a set vehicle speed, and the like. Output request signal from the PC.

Further, the transmission 3 is for enabling the engine 1 to be kept rotating even when the vehicle is stopped. The transmission 3 transmits the torque by pressing the friction plates against each other. Various types of clutches, such as a general clutch, a fluid coupling (fluid coupling), a fluid type torque converter, a torque converter having a built-in lock-up clutch, an electromagnetic clutch, a powder clutch, and the like, can be employed.

The transmission 3 is connected to a forward / reverse switching mechanism 5. This is provided because a continuously variable transmission 6, which will be described later, cannot invert and output the input.
The forward / reverse switching mechanism 5 includes, for example, a 3
A mechanism having one rotating element, wherein one of the rotating elements is connected to the transmission 3 to be an input element, and the other one is a fixed element that is selectively fixed,
The remaining one rotation element is an output element. By fixing the fixed element by a brake mechanism or the like, the output element rotates in the opposite direction with respect to the input element, and by releasing the fixed element and connecting any two rotating elements integrally. , As a whole, and the input is output as it is.

The continuously variable transmission 6 connected to the forward / reverse switching mechanism 5 will be described. The point of the continuously variable transmission 6 is that the speed ratio of the input shaft 7 and the output shaft 8 is continuously adjusted. This is a mechanism for changing, specifically, an appropriate type of continuously variable transmission such as a belt type or a toroidal type. An electronic control unit (ECU) 9 for electrically controlling the gear ratio is provided. The electronic control unit 9 is connected to the electronic control unit 4 for the engine 1 so as to be able to perform data communication, and receives data necessary for controlling the gear ratio.

The output shaft 8 of the continuously variable transmission 6 is connected to a final reduction gear (differential gear) 10;
The differential gear 10 distributes torque to the right and left wheels while allowing differential rotation of the wheels.

The gear ratio of the continuously variable transmission 6 is controlled by feedback control (proportional integral (PI) feedback control or proportional differential integral (PID) feedback control) by reading the input rotational speed and the output rotational speed. ing. This is performed, for example, in a belt-type continuously variable transmission by controlling the groove width of each pulley by hydraulic pressure based on the difference between the actual speed ratio and the target speed ratio. On the other hand, if there is an acceleration request such as depression of an accelerator pedal (not shown) and a shift request accompanying the acceleration request, the shift is started at the shift speed corresponding to the shift request, and thereafter, at the predicted shift end time point. On the other hand, the control for suppressing the vehicle longitudinal vibration is started at a point in time that is １ ／ cycle of the vehicle longitudinal vibration expected to occur at the end of the shift. Specifically, the shift speed is halved or reduced according to the viscosity characteristics of the power transmission system. After the input speed to the continuously variable transmission 6, that is, the engine speed reaches the target speed, the speed ratio is feedback-controlled. When the control for suppressing the longitudinal vibration of the vehicle ends and the process shifts to the feedback control, the control device according to the present invention for the power transmission system including the above-described continuously variable transmission performs the following control.

That is, FIG. 1 is a flowchart for explaining a control example according to the first aspect of the present invention.
It is configured to be determined in relation to the feedback control. First, in step 1, the rapid shift speed ΔNtran
0 and the engine speed Ne1 at the time of starting the vehicle longitudinal vibration suppression control are input. Here, the rapid shift is a shift in which the rate of change of the accelerator opening becomes greater than or equal to a predetermined value when the accelerator pedal is greatly depressed, and the shift speed Δ at that time.
As Ntran0, a value set in advance in the form of a map using, for example, the accelerator opening and the vehicle speed as parameters is adopted. Further, the engine speed N at the time when the vehicle longitudinal vibration suppression control is started.
e1 predicts the shift end point when the gear is shifted at the above-mentioned shift speed ΔNtran1 and, from that point, one of the vehicle longitudinal vibrations
It can be calculated and calculated as a point in time before / 2 cycle.

Next, at step 2, the engine speed Ne2 at the end of the vehicle longitudinal vibration suppression control is predicted.
This can be obtained by adding the amount of change in the engine rotational speed due to the execution of the vehicle longitudinal vibration suppression control to the engine rotational speed Ne1 at the time when the vehicle longitudinal vibration suppression control is started. Ne2 = Ne1 + β · ΔNtran0 · ts (1) Here, β is a value based on the viscosity of the power transmission system, and ts is an execution period of the vehicle longitudinal vibration suppression control. These are determined by the following equations. First,
The moment of inertia I1 of the power transmission system and the moment of inertia I2 due to the weight of the vehicle are obtained by I1 = ((R · Rd) ² ) · I + Rd ² · Iout (2) I2 = M · r ² (3) Here, R is the speed ratio set by the continuously variable transmission 6, and Rd is the final reduction gear (differential gear).
, I is the moment of inertia on the input side of the continuously variable transmission 6, Iout is the moment of inertia on the output side of the continuously variable transmission 6,
M is the vehicle weight, and r is the tire radius. Based on these, the angular velocity ω is calculated by ω = ((I 1 + I 2) / (I 1 · I 2) × k) ^1/2 (4) Here, k is a torsional spring coefficient of the power transmission system. Then, based on the angular velocity, the period T0 of the longitudinal vibration is calculated by T0 = 2 · pi / ω (5). Where pi is the pi. Therefore, by substituting the value of the target gear ratio R1 into R in the above equation, the period T1 of the longitudinal vibration at the target gear ratio R1 is obtained.

Further, the viscous damping coefficient η is determined from the viscous damping c of the power transmission system by η = c / 2 · ((I1 + I2) / (I1 · I2 · k)) ^1/2 (6) . Then, the period ts for suppressing the longitudinal vibration of the vehicle
Ts = pi / ((1−η ² ) ^1/2 · ω) (7)

Β in the above equation (1) is as follows: β = 1−1 / (1 + exp (−1 × η × π / ((1−η ² ))
^1/2 )))). If the viscosity can be ignored, the viscosity damping coefficient η becomes zero, and β is １ ／.

Since the feedback control (PI control or PID control) is performed based on the difference between the engine speed Ne2 and the target engine speed Net predicted in this manner, the shift speed ΔNtran2 at that time is ΔNtran2 = P × (Net−Ne2) (step 3). Note that P
Is a feedback proportional constant.

The shift speed at the time of the control for suppressing the vehicle longitudinal vibration can be determined based on the shift speed immediately before the control and the shift speed immediately after the control. The shift speed ΔNtran1 for control is set to an intermediate value between the previous and next shift speeds (step 4). That is, ΔNtran1 = β × (ΔNtran0−ΔNtran2) + ΔNtran2 (8) If the viscosity of the power transmission system can be ignored, β is が
In this case, the shift speed ΔNtran1 for the vehicle longitudinal vibration suppression control is an average value of the shift speeds before and after the shift speed ΔNtran1.

The shift speed ΔNtran1 for the vehicle longitudinal vibration suppression control obtained in this manner is based on the predicted value of the engine speed ΔNtran2 at the end of the control, and therefore inevitably includes an error. . Therefore, in order to perform more accurate control, it is preferable to repeat the above calculation. In the example shown in FIG. 1, the calculation is repeated using the predicted shift speed ΔNtran1 for the vehicle longitudinal vibration suppression control. Repeat several times.

That is, in step 5, a second prediction of the engine speed Ne2 at the end of the vehicle longitudinal vibration suppression control is performed. This can be calculated using the shift speed ΔNtran1 for suppressing the vehicle longitudinal vibration described above, and specifically, Ne2 = Ne1 + ΔNtran1 × ts (9) Next, at step 6, the shift speed ΔNtran2 at the end of the vehicle longitudinal vibration suppression control is predicted using this value. This is the same as the calculation in step 3 described above, and ΔNtran2 = P × (Net−Ne2) (10)

In step 7, a shift speed ΔNtran1 for vehicle longitudinal vibration suppression control is calculated using the shift speed ΔNtran2 predicted by the second time. This second calculation can be performed in the same manner as in step 4 described above, and can be obtained by ΔNtran1 = β × (ΔNtran0−ΔNtran2) + ΔNtran2 (11)

FIG. 2 shows the change in the engine speed Ne when the shift is executed at the shift speed determined by the above calculation.
This is schematically shown in the time chart of FIG. When a so-called sudden shift is requested, the shift is performed at the shift speed ΔNtran0 according to the request. When the engine speed Ne1 at which the vehicle longitudinal vibration suppression control is started is reached (time t1), the shift speed is reduced to ΔNtran1. Let me do. The shift at the shift speed ΔNtran1 is continued for ts, and t2
At this point, the vehicle longitudinal vibration suppression control ends. Then, the speed change at time t2 is set to ΔNtran2, and the feedback control of the engine speed Ne is started.

In this control process, the shift speed ΔNtran1 for the vehicle longitudinal vibration suppression control is set to an average value of the shift speeds before and after the control or an intermediate value in consideration of the viscosity. In the vehicle longitudinal vibration suppression control, about half of the inertia torque finally released when the gearshift is continued is released. Then, since the shift speed ΔNtran2 at the start of the feedback control following the vehicle longitudinal vibration suppression control matches the feedback proportional constant, almost half of the remaining inertia torque is released here. As a result, when shifting from the vehicle longitudinal vibration suppression control to the feedback control, the inertia torque is excessively released, or conversely, the release of the inertia torque becomes insufficient and the inertia torque is released immediately thereafter. Is prevented beforehand.

Here, the relationship between the above specific example and the invention of claim 1 will be described. The functions of steps 3 and 6 correspond to the means for predicting the shift speed in claim 1 and The function of No. 7 corresponds to the means for calculating the shift speed in the first aspect.

When shifting from the above-described vehicle longitudinal vibration suppression control to the feedback control, the inertia torque at the time when the vehicle longitudinal vibration suppression control is completed is controlled so as not to affect the feedback control. The transition can be smooth. Another control example for that purpose will be described below.

The examples shown in FIGS. 3 and 4 show an example of the second aspect of the present invention. In the example shown in FIG. 3, the shift speed between the vehicle longitudinal vibration suppression control and the feedback control is zero. This is an example of setting a period. That is, in FIG. 3, first, it is determined whether or not it is a rapid shift period (step 11). The rapid shift period is a period in which the shift is performed at the above-described shift speed ΔNtran0 when the operation amount of the accelerator pedal is equal to or greater than a predetermined value. During this period, for example, as described above, the shift speed ΔNtran0
From the end of the gear shift when the gear is shifted by 1 /
It can be set up to the point two cycles before. Immediately after the start of the shift, the shift is being executed at the initial shift speed ΔNtran0, so that an affirmative determination is made in step 11.

In that case, feedback (PI
Feedback or PID feedback) permission flag Fpi is set to "0" (step 12). The feedback permission flag Fpi is a flag that indicates that the feedback control is prohibited by being set to “0” and conversely indicates that the feedback control is permitted by being set to “1”. . Subsequently, the delay counter Cdelay is reset to zero (step 13).

If the engine speed Ne has reached the engine speed Ne1 at which the vehicle longitudinal vibration suppression control is started as the shift progresses, a negative determination is made in step 11. In that case, step 14
It is determined whether or not the vehicle longitudinal vibration suppression control is being performed. This vehicle longitudinal vibration suppression control is control for reducing the shift speed, and as an example, the initial shift speed ΔN
This is control to continue shifting at a shift speed ΔNtran1 obtained by multiplying tran0 by the aforementioned β. The continuation time ts can be obtained by, for example, the above equation (7). If the vehicle longitudinal vibration suppression control is being performed, the feedback control is not performed, so if a negative determination is made in step 14, the process proceeds to step 12.

The vehicle longitudinal vibration suppression control is continued for the above-mentioned time ts.
Is negative. When the above-described vehicle longitudinal vibration suppression control ends, the shift speed is set to zero. That is, the engine speed Ne is maintained at the current speed Ne2. This control is performed based on a control routine (not shown). At the same time, it is determined whether or not the value of the delay counter Cdelay is smaller than a predetermined reference value Ctd (step 15).

Since the delay counter Cdelay is set to "0" until the vehicle longitudinal vibration suppression control is completed, an affirmative determination is initially made in step S15. Therefore, at step 16, the delay counter Cdelay is counted up by "1". That is, the routine shown in FIG. 3 is executed at predetermined time intervals, and the delay counter Cdelay
Is incremented by "1" each time.

When the control for maintaining the engine speed Ne at a constant value is continued and the count value of the delay counter Cdealy reaches the reference value Ctd, that is, when the shift speed is reduced to zero, the engine speed Ne is maintained at a constant value. If the elapsed time reaches the reference time, a negative determination is made in step 15,
The feedback permission flag Fpi is set to "1" (step 17). As a result, feedback control of the engine speed Ne is started according to another control routine not shown.

The change in the engine speed Ne when the control shown in FIG. 3 is executed is shown in the time chart of FIG. After the start of the shift, the initial shift speed ΔN until t1
The gear is shifted at tran0, and the engine speed Ne is Ne1
From the time t2 when the shift speed reaches ΔNtran1 (= β ·
ΔNtran0), and the vehicle longitudinal vibration suppression control is executed. At time t2 when the continuation time reaches the above-mentioned period ts, the shift speed is set to zero, and the engine speed Ne is set.
Is maintained at a constant value Ne2. Feedback control is started at time t3 when the period during which the shift speed is zero reaches a predetermined time td.

Therefore, when the feedback control is started, the inertia torque and the torsional torque associated with the previous shift control have been eliminated, so that the vehicle longitudinal vibration suppression control does not become a disturbance factor for the feedback control. Therefore, according to the control shown in FIG. 3 and FIG. 4, it is possible to smoothly shift from the control of suppressing the longitudinal vibration of the vehicle to the feedback control, and it is possible to prevent the deterioration of the riding comfort due to shock or vibration.

Here, the relationship between the specific examples shown in FIGS. 3 and 4 and the invention of claim 2 will be described.
The functions of Nos. 6 and 17 correspond to the means for setting the shift speed to substantially zero in the second aspect of the present invention.

Next, the invention described in claim 3 will be described with reference to specific examples shown in FIGS. The control example shown here is an example in which the shift speed is controlled by hood forward control of the shift speed so as not to cause longitudinal vibration of the vehicle due to inertia torque or torsional torque accompanying the shift and feedback control based on the rotational speed deviation. Also in this case, following the shift at the shift speed in accordance with the shift request, control for lowering the shift speed for preventing overshooting of the driving torque at the end of the shift (that is, vehicle longitudinal vibration suppression control) is executed. Controls the number of rotations by feedback control. Therefore, as shown in FIG. 5, a shift speed ΔNtran for suppressing vehicle longitudinal vibration is first set (step 21).

This is for suppressing the longitudinal vibration of the vehicle which is started at a time half the period of the longitudinal vibration of the vehicle from the end of the shift when the gear is shifted at the beginning of the shift and when the gear is shifted at that speed. Includes both speed change. These shift speeds may be the same as those described in the control examples described above. Therefore, the shift speed at the start of the shift is a shift speed determined in advance based on the accelerator opening, the vehicle speed, the target engine speed, and the like. The subsequent shift speed for suppressing the vehicle longitudinal vibration is substantially half the initial shift speed or a shift speed obtained by multiplying the above-mentioned β in consideration of viscosity with the initial shift speed.

On the other hand, a deviation ΔNe (= Net−Ne) between the target engine speed Net and the current engine speed Ne.
And its accumulated value ΔNetotal (= ΔNetotal + ΔNe) are obtained (steps 22 and 23). Then, based on these values, the PI feedback gain ΔNpi of the shift speed is determined as ΔNpi = Kp × ΔNe + Ki × ΔNetotal (step 24). Here, Kp is a proportional constant in PI feedback control, and Ki is an integration constant in PI feedback control.

The PI feedback gain ΔNpi has an upper limit value ΔNpimax. The value is at least a value smaller than the shift speed for suppressing the vehicle longitudinal vibration. It is determined whether the PI feedback gain ΔNpi obtained in step 24 is larger than the upper limit value ΔNpimax (step 25). At least until the vehicle longitudinal vibration suppression control ends, the calculated PI feedback gain ΔNpi becomes larger than the upper limit value. In that case, a positive determination is made in step 25 and the process proceeds to step 26. That is, the PI feedback gain ΔNpi is set to the upper limit value ΔNpimax (step 26), and the cumulative value of the rotational speed deviation ΔNe, that is, the integral term ΔNetotal is set to zero (step 27). The reason why the integral term is set to zero in step 27 is to prevent the integral term from increasing while the PI feedback gain ΔNpi is suppressed to the upper limit value ΔNpimax, thereby avoiding overshoot.

Then, the shift speed Δ set in step 21
Ntran and the shift speed ΔNpi obtained in step 24 or step 26 are added to obtain a target shift speed ΔNtranf (step 28). Further, even when the negative determination is made in step 25 because the PI feedback gain ΔNpi is equal to or less than the upper limit value ΔNpimax, the routine proceeds to step 28, where the shift speed ΔNtran and the shift speed ΔNpi are added to obtain the target shift speed ΔNtranf. Therefore, the shift speed set by the control shown in FIG. 5 is increased by the PI feedback gain ΔNpi until the vehicle longitudinal vibration suppression control ends, as compared with the shift speed by the control shown in FIG. 1 or FIG. It will be.

Of the above-mentioned shift speed target value ΔNtranf, ΔNtran, which is the shift speed for suppressing vehicle longitudinal vibration, is set to a somewhat large value in response to a shift request or an engine output increase request at the beginning of shifting, and is predicted. The shift speed is reduced by almost half at a point in time 1/2 the cycle of the vehicle longitudinal vibration before the shift end time, and the vehicle longitudinal vibration suppression control period ts elapses. The set shift speed, that is, the shift speed by the feedforward control becomes zero. At that time, there is a deviation ΔNe between the target engine rotation speed Net and the actual engine rotation speed Ne.
PI feedback control based on e is continued.

Since the gain ΔNpi by the PI feedback control is limited to the upper limit value ΔNpimax or less as described above, the PI feedback gain ΔNpi due to the large rotation speed deviation ΔNe after the vehicle longitudinal vibration suppression period ts has elapsed. Is greater than the upper limit value ΔNpimax, the shift speed ΔNtran is equal to the upper limit value ΔNpimax.
Is set to Then, as the time elapses, the rotational speed deviation Δ
As Ne decreases, the PI feedback gain Δ
Npi decreases. The engine speed Ne is set to the target speed Net.

According to the above-described control, the PI feedback control in which the feedback gain is limited to a constant value is executed immediately after the control of the shift speed by the feedforward control is completed. And that restricted P
The I feedback gain ΔNpimax is included in the control amount even during the execution of the feedforward control. Therefore, it is possible to smoothly shift to the feedback control after the control of the shift speed by the feedforward control is completed. As a result, not only overshoot of the driving torque at the end of the shift, but also
It is possible to effectively prevent torque fluctuation due to control disturbance and shock or vibration resulting therefrom.

FIG. 6 is a time chart when the control shown in FIG. 5 is performed. When a shift request is generated due to depression of an accelerator pedal or the like, the shift speed ΔNtran is set based on the accelerator opening, the vehicle speed at that time, and the like. At the same time, the PI feedback gain Δ based on the rotational speed deviation ΔNe at that time
Npi is calculated. Although the calculated value becomes a considerably large value due to the large rotational speed deviation ΔNe, the upper limit value ΔN
Because pimax is set, its upper limit value ΔNpima
Set to x. These shift speeds ΔNtran, ΔNpima
The shift speed is controlled by the control amount ΔNtranf to which x is added. This control is continued up to a time point t1 which is 1/2 of the predicted vehicle longitudinal vibration cycle with respect to the predicted shift end time point.

Thereafter, the shift speed ΔNtran in the feedforward control based on the shift request is substantially reduced by half, or the shift speed obtained by multiplying the initial shift speed by the aforementioned β, and the upper limit value ΔNpi of the PI feedback gain.
Control at the shift speed obtained by adding max is continued during a so-called vehicle longitudinal vibration suppression period ts. At this time t2, the shift speed ΔNtran by the feedforward control becomes zero, but the shift speed ΔNpimax in the PI feedback control due to the presence of the rotational speed deviation ΔNe continues for a predetermined period. This is because the PI feedback gain ΔNpi obtained based on the rotational speed deviation ΔNe is equal to the upper limit value ΔNpimax.
Is continued until the time point t3 when the value falls below t. Thereafter, the shift speed ΔNtranf gradually decreases as the rotational speed deviation ΔNe decreases,
Eventually, the engine speed Ne matches the target value Net, and the shift speed becomes zero. That is, also in this control, after the shift speed control by the feedforward control is completed, the shift speed is maintained at a constant value lower than before, and as a result, the feedback control of the shift speed is smoothly performed. Can be migrated.

Here, the relationship between the specific examples shown in FIGS. 5 and 6 and the invention of claim 3 will be described. The function of step 28 sets the shift speed in the invention of claim 3 to an added value. Step 26 corresponds to a means for suppressing the control amount by the feedback control to the upper limit value.

Although the specific example described above is an example in which the PI feedback control is employed as the feedback control of the shift speed, the present invention employs various modes as required, such as PID feedback control as the feedback control of the shift speed. Can be adopted,
It is not limited to the above specific example. Also, the speed control is
In the case of a belt-type continuously variable transmission, the oil pressure may be controlled to change the groove width of each pulley at a desired speed, and in the case of a toroidal-type continuously variable transmission, the inclination speed of the power roller may be controlled. .

In the second aspect of the present invention, the shift speed is maintained at substantially zero before the feedback control is started, because the inertia torque and the torsional torque associated with the previous shift are released to start the feedback control. The shift speed immediately before the feedback control does not have to be completely zero, and is a slight shift speed in a range where no special influence is exerted on the feedback control. You may.

Further, in the present invention, the upper limit of the feed back gain may be a value smaller than the shift speed for suppressing vehicle longitudinal vibration immediately before the feed speed.
As an example, a shift speed that is 1/2 of the immediately preceding shift speed,
Alternatively, it may be a value in a predetermined range centered on の of the immediately preceding shift speed.

[0057]

As described above, according to the first aspect of the present invention, the shift speed set for suppressing the vehicle longitudinal vibration is predicted based on the subsequent shift speed at the start of the feedback control. Since the vehicle longitudinal vibration suppression control is performed based on the prediction result, it is possible to smoothly shift from the vehicle longitudinal vibration suppression control to the feedback control, and as a result, it is possible to prevent shock, vibration, and the like.

According to the second aspect of the present invention, the period in which the gear speed is substantially zero is set immediately before the feedback control for maintaining the target gear ratio is started. The torque accompanying the gear shift such as torque is released, and this does not affect the feedback control. Therefore, the transition to the feedback control becomes smooth, and shock and vibration can be prevented.

Further, according to the third aspect of the present invention, the feedback for setting the gear ratio to the target gear ratio is executed from the beginning of the gear shift, and the upper limit value of the control amount is set small. At the end of the shift speed control, there is a period in which the shift speed is maintained at a relatively small value, and thereafter, the shift speed is controlled substantially based on the rotational speed deviation. The influence of the speed control is eliminated or reduced, and shock, vibration, and the like when shifting to the feedback control can be prevented.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining a control example according to the invention of claim 1;

FIG. 2 is a time chart when the control according to the first aspect of the present invention is executed.

FIG. 3 is a flowchart for explaining a control example according to the invention of claim 2;

FIG. 4 is a time chart when the control according to the invention of claim 2 is executed.

FIG. 5 is a flowchart for explaining a control example according to the invention of claim 3;

FIG. 6 is a time chart when the control according to the invention of claim 3 is executed.

FIG. 7 is a block diagram schematically showing an example of a power transmission system to which the present invention can be applied.

[Explanation of symbols]

Reference numeral 1 denotes a prime mover, 4, 9 denotes an electronic control unit, 6 denotes a continuously variable transmission.

Claims (3)

[Claims] A shift is performed at a predetermined shift speed in response to a shift request, and at a predetermined time before reaching a target gear ratio, a shift speed is set for suppressing vehicle longitudinal vibration, and a shift is performed for vehicle longitudinal vibration. A control device for a vehicle having a continuously variable transmission that sets a target gear ratio by feedback control after shifting at a speed, comprising: means for predicting a shift speed at the time of starting the feedback control; Means for calculating the shift speed for suppressing the vehicle longitudinal vibration based on the shift speed immediately before setting the shift speed for suppressing the vehicle longitudinal vibration. Vehicle control device. 2. A gear shift is performed at a predetermined gear shift speed in response to a gear shift request, and at a predetermined time before reaching a target gear ratio, a gear shift speed is set to suppress vehicle longitudinal vibration, and a shift is performed for vehicle longitudinal vibration. In a control device for a vehicle having a continuously variable transmission that sets a target gear ratio by feedback control after shifting at a speed, a time period for setting a shift speed for suppressing the vehicle longitudinal vibration and a time when the feedback control is started A control device for a vehicle equipped with a continuously variable transmission, comprising: means for controlling the speed of the transmission to be substantially zero. 3. A shift is performed at a predetermined shift speed in response to a shift request, and at a predetermined time before reaching a target gear ratio, a shift speed is set for suppressing vehicle longitudinal vibration, and a shift is performed for vehicle longitudinal vibration. A control device for a vehicle having a continuously variable transmission that sets a target gear ratio by feedback control after shifting at a speed, wherein at least the shift speed for suppressing the vehicle longitudinal vibration is controlled by a shift speed by feedforward control and feedback control. Means for controlling the shift speed to the sum of the shift speed and means for limiting the upper limit value of the shift speed by the feedback control to a value smaller than the shift speed for suppressing vehicle longitudinal vibration at the predetermined time. A control device for a vehicle provided with a continuously variable transmission.