JP3267135B2 - Transmission control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a shift control device for a continuously variable transmission.

[0002]

2. Description of the Related Art Continuously variable transmissions used in vehicles include:
Conventionally, there are a belt type and a toroidal type. In these continuously variable transmission shift control devices, a target engine speed Ne * (a target input speed Nin) is determined according to a vehicle speed VSP and a throttle opening TVO (or an accelerator opening). Is known, and for example, there is one disclosed in JP-A-59-212565.

[0003] When accelerating from a low engine rotational speed, the speed of the continuously variable transmission is gradually increased with the lapse of time within a predetermined time at the initial stage of acceleration, and this increasing characteristic is reduced to the vehicle speed. By setting accordingly, it is possible to prevent a decrease in the speed ratio e (output shaft rotation speed Nout / input shaft rotation speed Nin) due to acceleration and a delay in rising of the vehicle speed due to a large inertia moment of the drive system, and to prevent the vehicle speed from rising. In spite of this, smooth acceleration is performed.

Further, as disclosed in Japanese Patent Application Laid-Open No. 60-53261, the speed ratio e after the engine rotation speed exceeds the margin output rotation speed until the vehicle reaches the target rotation speed during acceleration of the vehicle.
Is suppressed, the reduction in power transmission efficiency caused by the change in the speed ratio e is eliminated, and the fuel economy during acceleration is improved.

[0005]

However, in the above-described transmission control apparatus for a continuously variable transmission, the change in the gear ratio in the direction in which the engine speed increases is always suppressed, and the target engine speed and the actual engine speed are controlled. Smooth acceleration can be achieved with a configuration that only suppresses the speed ratio change speed in accordance with the difference in the number of revolutions. However, as another means for achieving the same purpose, for example, the target engine speed increases. In the case of setting a time delay in the direction to suppress the speed ratio change speed, not only during kickdown acceleration but also during start acceleration, a time delay occurs until the target engine speed is reached. As a result, there is a problem that the vehicle starts at a speed ratio slightly higher than the lowest Low speed ratio and the starting acceleration performance is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to smoothly start acceleration while suppressing the change speed of the target engine speed.

[0007]

According to the present invention, as shown in FIG. 7, a control target value for setting a target input rotational speed Ne * of the continuously variable transmission 60 in accordance with a vehicle speed VSP and an accelerator pedal opening TVO. Setting means 62, speed ratio change speed regulating means 63 for suppressing the change speed of the target input speed Ne *, and speed change control for setting the speed ratio of the continuously variable transmission 60 in accordance with the target input speed Ne * In the transmission control device for a continuously variable transmission provided with the means 61, the input for comparing the difference between the target input speed Ne * set by the control target value setting means 62 and the actual input speed Ne with a predetermined value e0. A rotational speed comparing means 64 and a means 65 for inhibiting the suppression of the change speed while the difference is smaller than a predetermined value e0 are provided.

[0008]

Accordingly, the target input speed Ne * of the continuously variable transmission is shown.
Is set in accordance with the vehicle speed and the accelerator pedal opening TVO. When the difference between the target input rotation speed Ne * and the actual input rotation speed Ne is equal to or greater than a predetermined value e0, the target according to the accelerator pedal opening is set. While the change speed of the input rotation speed Ne * is suppressed, smooth acceleration can be performed, while the target input rotation speed N
While the difference between e * and the actual input rotation speed Ne is smaller than a predetermined value e0, suppression of the change speed of the target input rotation speed Ne * is prohibited, and the target input rotation speed Ne * according to the opening degree of the accelerator pedal.
Is set, the shift to the Hi side during the start acceleration is prevented, and the start acceleration performance can be secured.

[0009]

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

FIG. 1 shows a case where the continuously variable transmission 1 is constituted by a toroidal type continuously variable transmission 10 which continuously changes the gear ratio according to the tilt angle of the two power rollers 18 and 20. The continuously variable transmission 1 includes a hydraulic control device 4 that controls the speed ratio of the continuously variable transmission 10 in accordance with a command from the shift control controller 2.

The continuously variable transmission 10 has a forward / reverse switching device 40 interposed between the engine and the torque converter 12, and has a hydraulic control unit 4 supplied with hydraulic pressure from a hydraulic pump 84 to change the gear ratio i. Is what you do. The torque converter 12 is provided as a starting element. At a predetermined speed or higher, a lock-up (LU) clutch (not shown) operates, and the engine and the continuously variable transmission 1 are driven.
The 0 input shaft is directly connected.

The hydraulic control device 4 of the continuously variable transmission 1 has a step motor 61 driven by a shift control controller 2 mainly composed of a microcomputer.

The shift control controller 2 determines the actual engine speed Ne and the throttle opening TVO (or the accelerator opening) input from the engine control controller 3, the selector position of the shift lever 5 from the selector switch 5A, and Input shaft rotation sensor 6 arranged in step transmission 10
And the input shaft rotation speed Nin (= actual engine rotation speed Ne) and the output shaft rotation speed Nout (= vehicle speed VSP) from the output shaft rotation sensor 7, respectively, and read the target engine rotation speed Ne * according to the driving state of the vehicle. (= Target speed ratio i *) is calculated. The output shaft rotation sensor 7 functions as a vehicle speed sensor that detects the vehicle speed VSP, and the shift control controller 2
Is the vehicle speed VSP obtained by multiplying the output shaft rotation speed Nout by a predetermined constant.
Is calculated.

Then, the transmission control controller 2 drives the step motor 61 of the hydraulic control device 4 based on the calculated target transmission ratio i *, and the toroidal type continuously variable transmission 10
The power rollers 18 and 20 are driven such that the tilt angles (actual gear ratios) of the power rollers 18 and 20 match the target gear ratio i *, and feedback control or the like is performed according to the actual gear ratio of the continuously variable transmission 10. .

Here, the transmission control controller 2 is configured as shown in FIG.
As shown in the figure, a CPU 50 for performing arithmetic processing is mainly used, and a RAM 51 and a ROM 52 are provided as storage means.
Further, the A / D converter 53 reads the throttle opening TVO from the engine control controller 3, and the actual engine speed Ne from the engine control controller 3,
Digital I / O for reading signals from the counter 54 for inputting the rotation speeds Nin and Nout (= vehicle speed VSP) of the input / output shafts of the continuously variable transmission 10 and the selector switch 5A of the shift lever 5
O55, and the step motor 61 of the hydraulic control device 4
And the like, and a digital I / O 56 for driving the same.

Here, the ROM of the transmission control controller 2
A predetermined shift map is stored in the storage means such as 52 in advance.

Next, an example of the control performed by the shift control controller 2 is shown in the flowcharts of FIGS.
4 shows a main routine, and FIGS. 4 and 5 show subroutines, which are sequentially executed at predetermined time intervals, for example, at every 10 msec.

In step S1 of FIG. 4, data is read from various sensors and the like to detect the operating state of the vehicle. The engine speed Ne and the throttle opening TVO are read from the engine controller 3 and the continuously variable transmission. 1 to input shaft speed Nin, output shaft speed Nout
(Vehicle speed VSP).

In step S2, based on the shift map set in advance as shown in FIG. 6, as shown in the flowchart of FIG. 4, the target engine speed corresponding to the vehicle speed VSP is set with the throttle opening TVO as a parameter. N
Search and set e * (= target input shaft speed).

Next, in step S3, it is determined whether or not the set target engine speed Ne * is larger than the actual engine speed Ne.
If the target engine speed Ne * is less than the actual engine speed Ne, the routine proceeds to step S5, where the control flag FLAG is set to 0.
To clear.

In step S4, the target engine speed N
It is determined whether the difference (Ne * -Ne) between e * and the actual engine speed Ne is less than a predetermined value e0. When the difference is less than the predetermined value e0, the process proceeds to step S5 in the same manner as described above. If it is equal to or greater than the predetermined value e0, the process proceeds to step S6, where a time delay is set to the target engine speed Ne *. The predetermined value e0 is set to a very small value.

The time delay setting process in step S6 is performed as shown in FIG.
First, if the control flag FLAG is 0 in step S20, the process proceeds to step S20.
Proceed to 21 to perform initialization.

In step S21, the timer Timer is set to 0.
Then, in step S22, the current actual engine speed Ne is set to the initial value Ne0 of the control engine speed, and in step S23, the control flag FLAG is set to 1 and the initialization ends.

Next, at step S24, the timer Timer
Is incremented, and in step S25, the initial value Ne0 obtained in step S22 and the timer Timer
Thus, a time delay is set for the target engine speed Ne * as in the following equation.

Ne * = Ne0 × K + Timer where K is a predetermined constant.

Therefore, when the difference between the target engine speed Ne * and the actual engine speed Ne is equal to or greater than the predetermined value e0,
The target engine speed Ne * is reset according to the elapsed time, and the target input speed Ne * is set with respect to the throttle opening TVO.
(= Transmission ratio), while the difference is less than the predetermined value e0, the setting of the time delay to the target engine speed Ne * is prohibited, and the speed is changed according to the throttle opening TVO. The target input speed Ne * is set.

After completion of the time delay setting process, the process returns to the main routine of FIG. 3, and in step S7, the target engine speed Ne * (= target input shaft speed).
The stepping motor 61 is driven such that the target speed ratio i * calculated from the above becomes equal to the actual speed ratio.

Thus, while the difference between the target engine speed Ne * and the actual engine speed Ne is small (less than the predetermined value e0)
Since the setting of the time delay of the target engine speed Ne * is prohibited, the vehicle is not shifted to the Hi side at the time of starting acceleration as in the conventional example, and the starting acceleration is smoothly changed from the lowest Low gear ratio. To ensure the starting acceleration performance, while the target engine speed Ne *
When the difference between the engine speed Ne and the actual engine speed Ne becomes equal to or more than a small predetermined value e0, a time delay is set, and the speed ratio change speed is suppressed with respect to the throttle opening TVO. As a result, the drivability of the vehicle provided with the continuously variable transmission can be improved.

In the above-described embodiment, an example is shown in which the continuously variable transmission 10 is configured as a toroidal type. However, although not shown, it can be configured as a belt type or the like.

[0030]

As described above, according to the present invention, when the difference between the target input speed Ne * and the actual input speed Ne is equal to or more than the predetermined value e0, the target input speed Ne corresponding to the opening degree of the accelerator pedal is obtained. * While the speed of change of * is suppressed, smooth acceleration can be performed. On the other hand, while the difference between the target input rotation speed Ne * and the actual input rotation speed Ne is smaller than a predetermined value e0, the target input rotation speed Ne * Since the suppression of the change speed is prohibited and the target input rotation speed Ne * is set in accordance with the opening degree of the accelerator pedal, the shift to the Hi side during the start acceleration as in the conventional example is prevented, and the start acceleration performance is improved. As a result, it is possible to improve the drivability of a vehicle equipped with a continuously variable transmission by achieving both smooth acceleration and start acceleration performance.

[Brief description of the drawings]

FIG. 1 is a block diagram of a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a block diagram showing details of a shift control controller.

FIG. 3 is a flowchart of a main routine showing an example of control performed by a shift control controller.

FIG. 4 is a flowchart of a subroutine showing an example of a search process of a target engine speed Ne *.

FIG. 5 is a flowchart of a subroutine showing an example of a time delay setting process.

FIG. 6 is a shift map showing a relationship between a vehicle speed VSP and a target input rotation speed = a target engine rotation speed.

FIG. 7 is a claim correspondence diagram corresponding to the first or second invention.

[Explanation of symbols]

 2 Transmission control controller 3 Engine control controller 4 Hydraulic controller 6 Input shaft rotation sensor 7 Output shaft rotation sensor 10 Continuously variable transmission 12 Torque converter 18, 20 Power roller 40 Forward / reverse switching device 61 Step motor 84 Hydraulic pump 50 CPU 51 RAM 52 ROM 53 A / D 54 Counter 55, 56 Digital IO 60 Continuously variable transmission 61 Shift control means 62 Control target value setting means 63 Gear ratio change speed regulating means 64 Input speed comparison means 65 Prohibition means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F16H 63:06 F16H 63:06

Claims (1)

(57) [Claims] 1. A control target value setting means for setting a target input rotation speed of a continuously variable transmission according to a vehicle speed and an opening degree of an accelerator pedal, and a speed ratio change speed restriction for suppressing a change speed of the target input rotation speed. And a shift control device for setting the speed ratio of the continuously variable transmission in accordance with the target input rotation speed, wherein the target input set by the control target value setting means is provided. An input rotation speed comparing means for comparing a difference between the rotation speed and the actual input rotation speed with a predetermined value; and a means for prohibiting suppression of the change speed while the comparison result indicates that the difference is smaller than a predetermined value. A shift control device for a continuously variable transmission, comprising: