JPH06100268B2 - Control method of continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a control method for a continuously variable transmission.

(2) Prior Art In shift control of a continuously variable transmission mounted on a vehicle, generally, an actual gear ratio is detected, a difference between this and a target gear ratio is calculated, and this difference is reduced. The shift actuator is controlled. When the accelerator pedal is depressed rapidly in order to obtain rapid acceleration, the continuously variable transmission needs to be rapidly shifted in order to improve the responsiveness. For this purpose, there is a control method for controlling the operating speed of the shift actuator of the continuously variable transmission according to the change speed of the deviation between the actual speed ratio and the target speed ratio (that is, the differential value of the deviation with respect to time). . For example, Japanese Patent Application No. 56-137826 filed by the applicant of the present application discloses a device for performing the above-mentioned control using an analog signal. In this case, since the analog signal is used, there is a time delay in the differentiation of the deviation, and the time during which the operating speed of the shift actuator is increased continues for some time. That is, the shift actuator does not operate at a high speed only while the deviation between the actual speed change ratio and the target speed change ratio is changing (for example, only at the moment when the accelerator pedal is depressed), and the change of the deviation stops. The operation speed of the speed change actuator is high for a predetermined time afterward (after stopping the depression of the accelerator pedal). Therefore, even if the deviation between the target gear ratio and the actual gear ratio changes very rapidly,
Since the operating speed of the shift actuator increases for a certain period of time, a quick shift can be performed.

(3) Problems to be Solved by the Invention However, if the same control is attempted by digital control as disclosed in Japanese Patent Laid-Open No. 50-146783, the following problem occurs. That is, in normal digital control, the following calculation is repeatedly executed at very short time intervals. First, the deviation E ₀ between the actual gear ratio and the target gear ratio at the time of the present calculation is calculated, and this deviation E ₀ is multiplied by the first constant K ₁ . Also, the difference e between the current deviation E ₀ and the deviation E ₋₁ at the previous calculation is calculated,
This is multiplied by the second constant K ₂ . Next, K ₁ · E ₀ and K ₂ · e are added, and the operating speed of the shift actuator is determined according to the value of the added value K ₁ · E ₀ + K ₂ · e. However, when the above calculation is performed, K ₂ · e has a large value only during the calculation when the deviation E ₀ changes abruptly, and has a small value during the other calculations. For this reason, although the value corresponding to the difference e corresponding to the differential value of the deviation E ₀ is added, there is practically no effect of increasing the operating speed of the shift actuator. That is, the operating speed of the shift actuator is controlled only in proportion to the deviation E ₀ , and the operating speed is slow and shifting takes time. In general, in continuously variable transmissions, the maximum value of the operating speed of the speed change actuator is set in order to protect the belt and the like from the shock that accompanies a rapid speed change, and the speed change actuator operates at a higher speed. I can't do that. In this case, since the time during which the operating speed of the gear shift actuator is increased is short and the maximum speed is limited, the gear shift speed becomes very slow.

The present invention aims to solve such problems.

(4) Means for Solving the Problems According to the present invention, the deviation at the time of calculation a number of times before is greater when the operating state requires a rapid gear shift, that is, when a larger gear change rate is required. To solve the above problems. That is, the control method of the continuously variable transmission according to the present invention determines the target gear ratio or the target engine speed of the continuously variable transmission according to the operating state of the vehicle, and determines the actual gear ratio or the actual gear ratio of the continuously variable transmission. The engine speed is detected, and the deviation between the target speed ratio or the target engine speed and the actual speed ratio or the actual engine speed is calculated as a digital signal.
And the difference between the deviation at the current calculation and the deviation at the previous calculation is calculated.
By adding a value obtained by multiplying the deviation by a first constant and a value obtained by multiplying the difference by a second constant, and controlling the operating speed of the shift actuator according to the added value. In the method for controlling the gear ratio, the previous calculation is characterized in that the calculation is performed a number of times before the calculation in a driving state requiring a rapid shift.

(5) Action Depending on the driving state of the vehicle, it is determined how many deviations before the deviation in the current calculation should be used in the current calculation. A predetermined calculation is executed using the selected deviation,
The shift control of the continuously variable transmission is performed based on the calculation result. As a result, even in an operating state in which rapid gear shifting is required, gear shifting control can be performed while ensuring good gear shifting responsiveness.

(6) Examples Hereinafter, the present invention will be described with reference to FIGS. 1 to 4 of the accompanying drawings.

FIG. 1 shows a configuration for carrying out the method of the present invention as a block diagram. Various signals 10 (for example, a vehicle speed signal, an engine speed signal, a throttle opening signal, etc.) indicating the operating state of the vehicle are input to the target gear ratio calculation device 100, and a target gear ratio signal 11 is input according to a predetermined calculation method. Is calculated.
The target gear ratio signal 11 is input to the gear ratio deviation calculation device 110. The actual gear ratio signal 21 calculated by the actual gear ratio calculation device 200 is also input to the gear ratio deviation calculation device 110. The gear ratio deviation calculation device 110 calculates the deviation E ₀ between the target gear ratio signal 11 and the actual gear ratio signal 21. The signal 12 indicating the deviation E ₀ is a multiplication section 120, a subtraction section 140, and a deviation reading section.
Entered in 300. In the multiplication unit 120, the deviation E ₀ is added to the first constant K ₁
Is loaded. The deviation reading unit 300 n times before the operation time of the deviation E _- n is taken out. The value of n is set by a command from the delay number calculation device 310. The delay number calculation device 310 determines the value of n as will be described later based on various signals 10 'such as the throttle opening indicating the operating state of the vehicle, engine intake pipe negative pressure and vehicle speed. The deviation E _{0 in the} subtractor 140
N it is subtracted _- n times before the deviation E from. Then, the multiplication unit 150
Then, the subtracted value E ₀ −E ₋ n is multiplied by the second constant K ₂ . The value K ₁ · E ₀ from the multiplication unit 120 and the value K ₂ · (E ₀ −
E _- n) is added by the addition unit 160, and the added value is K ₁ · E ₀ + K ₂
(E ₀ −E ₋ n) is sent to the speed change command device 170. The speed change command device 170 commands the operating speed of the speed change actuator 180, which is equal to or less than the maximum value of the operation speed of the speed change actuator described above, based on the added value. This controls the speed change speed of the continuously variable transmission 190.

The functions of the gear ratio deviation calculation device 110 to the adder 160 are shown in a flowchart of FIG. First, calculate the difference between the target gear ratio and the actual gear ratio,
E ₀ (561). Then, the deviation E ₀ is multiplied by the first constant K ₁ (562), and then the value of n is determined (563) to obtain the deviations E ₀ and n.
The difference from the deviation E _- n in the previous calculation is multiplied by the second constant K ₂ (564). Next, K ₁ · E ₀ and K ₂ · (E ₀ −E ₋ n) are added, and this is used as the shift speed signal (565). Next, it is determined whether the added value is equal to or more than a predetermined limit value (566). When the added value exceeds the limit value, the limit value is set as the shift speed signal (567). When the added value is less than or equal to the limit value, the added value is used as it is as the shift speed signal. Then, for the next calculation, each deviation in the memory is replaced once with the deviation from the previous calculation (ie,
E _- k _-1 ← E _- k) (568).

Next, FIGS. 3 (a) to 3 (f) show the state of change of each signal when the above control is performed. It is assumed that the target gear ratio signal changes stepwise as shown in FIG. 3 (a). In this case, the actual gear ratio (that is, the actual gear ratio signal) changes as shown in FIG. 3 (b). For this reason,
The deviation E ₀ between the target gear ratio signal and the actual gear ratio signal is the third (c)
It changes as shown in the figure. Deviation from the deviation E ₀ at n times before the operation E _- when n subtracting becomes as shown in 3 (d) FIG. The deviation E ₀ multiplied by the _first constant K ₁ and the difference E ₀ −E ₋
The value obtained by adding n to the product of the second constant K ₂ is the third
As shown in FIG. The value indicated by the broken line in FIG. 3 (e) is the shift speed limit value. Eventually, the shift speed signal has a waveform as shown in FIG. 3 (f). Therefore, even when the target speed ratio signal is changed stepwise, the speed change actuator operates at the maximum speed for t ₁ time (corresponding to n times of calculation time), and during t ₂ time. The operating speed decreases. Therefore, the gear shift actuator operates at high speed and a quick gear shift is performed.

For reference, the change in the signal when the difference is obtained by the difference between the deviation at the present calculation and the deviation at the previous calculation (that is, when n = 1)
(F) It shows in a figure. The difference from the example shown in FIG. 3 in this case is that in FIG. 4 (d), the difference appears only in the form of a pulse having a very short length. For this reason, the time t ₁ ′ in FIG. 4 (f) is extremely short (corresponding to one calculation time). For this reason, the actual operating speed of the speed change actuator is slower than that shown in FIG. 3, and the speed change response of the continuously variable transmission is poor.

The above-mentioned value of n is changed according to the driving conditions of the vehicle as follows. That is, for example, in the case of operating conditions in which the target gear ratio greatly changes (for example, when the accelerator pedal is suddenly depressed, when the shift lever is shifted from the D range to the L range), the value of n is increased. However, when the operating condition is such that the target gear ratio changes relatively small, the value of n is reduced.
By changing the value of n in this way, it is possible to quickly change the actual gear ratio even when the target gear ratio changes largely or slightly and to prevent overshoot or the like from occurring. it can.

In the above embodiment, the control is performed based on the deviation between the target gear ratio and the actual gear ratio. However, since the gear ratio and the engine rotation speed have a predetermined relationship, the target engine rotation speed and the actual engine speed are It is obvious that the same control as described above can be performed based on the deviation from the rotation speed.

(7) Effects of the Invention As described above, according to the present invention, it is possible to improve the responsiveness of the shift even in any driving state of the vehicle and to control so as not to cause the overshoot.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration for carrying out the method of the present invention, FIG. 2 is a diagram showing a flow chart of an operation by the method of the present invention, and FIG. 3 is a line showing changes of each signal obtained by the method of the present invention. FIG. 4 and FIG. 4 are diagrams showing, for comparison, changes in each signal when not using the method of the present invention. 100: Target gear ratio calculation device, 110: Gear ratio deviation calculation device, 170: Gear change speed command device, 180: Gear change actuator, 200: Actual gear ratio calculation device.

Claims (1)

[Claims] 1. A target gear ratio or a target engine speed of a continuously variable transmission is determined according to a driving state of a vehicle, and an actual gear ratio or an actual engine speed of the continuously variable transmission is detected.
The deviation between the target gear ratio or the target engine rotation speed and the actual gear ratio or the actual engine rotation speed is calculated as a digital signal, and the deviation is multiplied by a first constant. A difference from the deviation at the time of calculation is calculated, the difference is multiplied by a second constant, the deviation is multiplied by a first constant, and a value obtained by multiplying the difference by a second constant is added, In a control method of a continuously variable transmission for controlling a gear ratio by controlling an operating speed of a gear shift actuator in accordance with the added value, the previous calculation is performed as much as in an operating state requiring a rapid gear shift. And a control method for a continuously variable transmission, characterized in that the calculation is performed a number of times before.