JPH09203458A - Speed change control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a start acceleration function while restraining variation in target engine rotational speed. SOLUTION: A speed change control device comprises a target control value setting means 62 for setting a target input speed ne* of a continuous variable transmission 60 in accordance with a vehicle speed VSP and an opening degree TVO of an accelerator pedal, a speed change ratio variation limiting means 63 for restraining variation in the target input speed Ne*, a speed change control means 61 for setting a speed change ratio of the transmission 60 in accordance with the target input speed Ne*, an input speed comparing means 64 for comparing a difference between the target input speed Ne* set by the target control value setting means 62 and an actual input speed Ne, with a predetermined value e0, and a means 65 for inhibiting the restraint to the said variation in speed if the result of the comparison shows that the difference is smaller than the predetermined value e0.

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 belt type and toroidal type, and in these shift control devices for continuously variable transmissions, a target engine speed Ne * (target input speed Nin) is determined according to a vehicle speed VSP and a throttle opening TVO (or accelerator opening). Is known, and there is, for example, the one disclosed in JP-A-59-212565.

This is because, when accelerating from a state where the engine speed is low, within a predetermined time period at the initial stage of acceleration, the speed change speed of the continuously variable transmission is gradually increased with the passage of time, and this increasing characteristic is changed to the vehicle speed. By setting it accordingly, it is possible to prevent a decrease in the speed ratio e (output shaft speed Nout / input shaft speed Nin) due to acceleration and a delay in the start-up of the vehicle speed due to a large moment of inertia of the drive system. Despite this, smooth acceleration is performed.

Further, as disclosed in Japanese Patent Laid-Open No. 60-53261, the speed ratio e from the engine speed exceeding the margin output speed to the target speed e during acceleration of the vehicle.
By suppressing the change in the speed ratio e, the decrease in the 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 shift control device for a continuously variable transmission as described above, 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 reduced. Smooth acceleration can be achieved if the speed change ratio change speed is controlled only in accordance with the difference in the number of revolutions. However, as another means for achieving the same purpose, for example, the target engine revolution speed is increased. If a time delay is set in the direction to suppress the speed change ratio, there is a time delay not only during kickdown acceleration but also during start acceleration until the target engine speed is reached. Therefore, there is a problem that the vehicle is started at a gear ratio slightly on the Hi side of the maximum Low gear ratio, and the starting acceleration performance is deteriorated.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to smoothly perform start-up acceleration while suppressing a change speed of a target engine speed.

[0007]

According to the present invention, as shown in FIG. 7, a control target value for setting a target input speed Ne * of the continuously variable transmission 60 according to a vehicle speed VSP and an accelerator pedal opening TVO. Setting means 62, speed ratio change speed regulation means 63 for suppressing the speed of change of the target input speed Ne *, and speed change control for setting the speed ratio of the continuously variable transmission 60 according to the target input speed Ne *. In a transmission control device for a continuously variable transmission including means 61, an 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. The rotation speed comparison means 64 and means 65 for inhibiting the change speed from being suppressed while the comparison result indicates that the difference is smaller than the predetermined value e0.

[0008]

Therefore, the target input speed Ne * of the continuously variable transmission is
Is set according to the vehicle speed and the accelerator pedal opening TVO. However, when the difference between the target input speed Ne * and the actual input 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 speed Ne * is suppressed and smooth acceleration can be performed, the target input speed N
While the difference between e * and the actual input rotation speed Ne is smaller than the predetermined value e0, suppression of the changing speed of the target input rotation speed Ne * is prohibited, and the target input rotation speed Ne * corresponding to the opening of the accelerator pedal is prohibited.
Is set, it is possible to prevent shifting to the Hi side at the time of starting acceleration and to secure the starting acceleration performance.

[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 a gear ratio in accordance with tilt angles of two power rollers 18, 20. The continuously variable transmission 1 includes a hydraulic control device 4 that controls the gear ratio of the continuously variable transmission 10 in accordance with a command from the gear shift control controller 2.

In the continuously variable transmission 10, a forward / reverse switching device 40 is provided between the engine and the torque converter 12, and the gear ratio i is changed by the hydraulic control device 4 supplied with hydraulic pressure from the hydraulic pump 84. Is to do. The torque converter 12 is provided as a starting element, and a lock-up (LU) clutch (not shown) is activated at a predetermined speed or higher to operate the engine and the continuously variable transmission 1.
The 0 input shaft is directly connected.

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

The shift control controller 2 includes the actual engine speed Ne and the throttle opening TVO (or accelerator opening) input from the engine controller 3, the selector position from the selector switch 5A of the shift lever 5, and Input shaft rotation sensor 6 provided in the transmission 10
And the input shaft revolution speed Nin (= actual engine revolution speed Ne) and the output shaft revolution speed Nout (= vehicle speed VSP) from the output shaft revolution sensor 7, respectively, and the target engine revolution speed Ne * according to the operating state of the vehicle. (= Target gear 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 speed Nout by a predetermined constant.
Is calculated.

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

Here, the shift control controller 2 is shown in FIG.
As shown in FIG. 1, a CPU 50 that performs arithmetic processing is a main component, and a RAM 51 and a ROM 52 as storage means are provided.
Furthermore, the A / D converter 53 that reads the throttle opening TVO from the engine controller 3, the actual engine speed Ne from the engine controller 3,
Digital I / F for reading signals from the counter 54 for inputting the rotational speeds Nin and Nout (= vehicle speed VSP) 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
It is composed of a digital I / O 56 for driving etc.

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

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

In step S1 of FIG. 4, data is read from various sensors 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 is used. 1 to input shaft speed Nin, output shaft speed Nout
Read the signal from (vehicle speed VSP).

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

Next, in step S3, it is determined whether the set target engine speed Ne * is greater than the actual engine speed Ne. If it is larger, the process proceeds to step S4.
When 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 this difference is less than the predetermined value e0, the process proceeds to step S5 in the same manner as above, while the difference is When the value is equal to or greater than the predetermined value e0, the process proceeds to step S6 to set a time delay for the target engine speed Ne *. The predetermined value e0 is set to a small value.

The time delay setting process of step S6 is shown in FIG.
If the control flag FLAG is 0 in step S20, the process is performed as in the flow chart shown in FIG.
Proceed to step 21 to perform initialization.

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

Next, in step S24, a timer Timer
Is incremented, and then in step S25, the initial value Ne0 obtained in step S22 and the timer Timer are obtained.
Therefore, a time delay is set to 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 not less 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.
When the change speed of (= gear ratio) is suppressed 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 target engine speed Ne * is changed according to the throttle opening TVO. The target input speed Ne * is set.

After the time delay setting process is completed, the process returns to the main routine of FIG. 3, and in step S7, the target engine speed Ne * (= target input shaft speed) is reached.
The step motor 61 is driven so that the target gear ratio i * calculated from the above becomes equal to the actual gear 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 start-up acceleration as in the conventional example, and the smooth start-up acceleration is performed from the maximum Low gear ratio. It is possible to secure the starting acceleration performance while targeting the engine speed Ne * during kickdown acceleration.
When the difference between the actual engine speed Ne and the actual engine speed Ne becomes a slight predetermined value e0 or more, a time delay is set to suppress the speed change ratio of the gear ratio with respect to the throttle opening TVO. Therefore, smooth acceleration is performed as in the conventional example. Therefore, it is possible to improve the drivability of the vehicle equipped with the continuously variable transmission.

In the above embodiment, an example in which the continuously variable transmission 10 is of a toroidal type has been shown, but it is possible to form it by a belt type or the like, although not shown.

[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 greater than the predetermined value e0, the target input speed Ne depending on the opening degree of the accelerator pedal. While the change speed of * is suppressed and smooth acceleration can be performed, while the difference between the target input speed Ne * and the actual input speed Ne is smaller than the predetermined value e0, the target input speed Ne * Since the suppression of the changing speed is prohibited and the target input speed Ne * is set according to the opening degree of the accelerator pedal, the shift to the Hi side at the time of starting acceleration as in the above-mentioned conventional example is prevented and the starting acceleration performance is improved. Therefore, it is possible to ensure the smooth acceleration and the acceleration performance at the start of the vehicle, and to improve the drivability of the vehicle equipped with the continuously variable transmission.

[Brief description of drawings]

FIG. 1 is a block diagram of a continuously variable transmission showing 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 the shift control controller.

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

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

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

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

[Explanation of symbols]

 2 shift control controller 3 engine control controller 4 hydraulic control device 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 Rotation Speed Comparison Means 65 Inhibiting Means

Claims (1)

[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 of an accelerator pedal, and a gear ratio change speed regulation for suppressing a change speed of the target input rotation speed. Means and a shift control device for setting a gear ratio of the continuously variable transmission according to the target input speed, the target input value set by the control target value setting means. Input rotation speed comparison means for comparing the difference between the rotation speed and the actual input rotation speed with a predetermined value, and means for prohibiting the suppression of the changing speed while the comparison result shows that the difference is smaller than the predetermined value. A shift control device for a continuously variable transmission, comprising: