JPH07117146B2 - Controller for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a belt-type continuously variable transmission for a vehicle, and more particularly, to a shift control during rapid acceleration in a shift control targeting a change speed of a gear ratio (shift speed). Regarding the shift control of this type of continuously variable transmission, for example, there is a basic hydraulic control system disclosed in JP-A-55-65755. This is to set the gear ratio so that the gear ratio control valve is balanced by the factors of the accelerator depression amount and the engine speed, and the engine speed is always constant. ing. Therefore, the shift speed is mechanically determined by each gear ratio, line pressure, control valve, etc., and the shift speed cannot be directly controlled. Therefore, it has been pointed out that the gear ratio causes hunting, overshoot, and the like to deteriorate drivability in the transient state of the driving range. For this reason, in recent years, there has been a tendency to electronically control the transmission of a continuously variable transmission in consideration of the transmission speed.

[Prior art]

Therefore, conventionally, in the speed change control of the continuously variable transmission,
Regarding acceleration, for example, there is a prior art disclosed in JP-A-60-44652. Here, it is shown that the shift speed is controlled as a function of the depression amount of the acceleration pedal, the variation amount of the depression, and the like.

[Problems to be Solved by the Invention]

Here, the shift speed control is for controlling the actual value to follow the target value based on the relationship between the target value and the actual value, and there are closed loop feedback control and open loop control methods. Therefore, even if the element of the amount of change in the depression is added as in the above-mentioned prior art, it differs for each control method. Therefore, in the open-loop control method that the applicant of the present invention has already proposed, when performing correction during sudden acceleration, it is necessary to use a correction method suitable for it. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a control device for a continuously variable transmission, which is capable of improving the shift responsiveness during sudden acceleration in open-loop shift speed control. I am trying.

[Means for solving problems]

As a means for achieving this object, the present invention is such that a drive belt is wound between an input side pulley and an output side pulley whose pulley groove width is variably controlled by hydraulic pressure, and the drive belt is controlled according to a shift speed output from a control unit. In the continuously variable transmission that continuously changes the speed so that the actual speed ratio converges to the target speed ratio by controlling the supply and drain oil flow rate to the input side pulley via the speed change speed control valve by the control signal The unit has means for outputting a shift speed signal according to the deviation between the target speed ratio and the actual speed ratio, and the control unit detects the speed of change of the throttle opening corresponding to the depression amount of the accelerator pedal. When the detected throttle opening change speed exceeds a predetermined value, the larger the throttle opening change speed, the more the speed change speed is corrected and the throttle opening amount at the start of accelerator depression is increased. Characterized in that a means for reducing corrected degree shift speed.

[Action]

In the present invention employing such means, the actual gear ratio converges to the target gear ratio at a gear speed that corresponds to the deviation from the target gear ratio, and during rapid acceleration in which the throttle opening change speed exceeds a predetermined value, The shift speed is increased and corrected according to the throttle opening change speed, and at the same time, the shift speed is decreased and corrected according to the throttle opening when the throttle opening change speed exceeds a predetermined value.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be described. An engine 1 is connected to a main shaft 5 of a continuously variable transmission 4 via a clutch 2 and a forward / reverse switching device 3. . In the continuously variable transmission 4, the sub shaft 6 is arranged in parallel with the main shaft 5, the main shaft 5 is provided with a primary pulley 7, the sub shaft 6 is provided with a secondary pulley 8, and the pulleys 7 and 8 are provided on the movable side. The hydraulic cylinders 9 and 10 are equipped and the drive belt 11 is wound. Here, the primary cylinder 9 is set to have a larger pressure receiving area, and the primary pressure changes the ratio of the winding diameter of the drive belt 11 to the pulleys 7 and 8 for continuously variable transmission. The auxiliary shaft 6 is connected to the output shaft 13 via a pair of reduction gears 12, and the output shaft 13 is configured to be transmitted to a drive wheel 16 via a final gear 14 and a differential gear 15. Next, the hydraulic control system of the continuously variable transmission 4 will be described. The oil pump 20 is driven by the engine 1, and the line pressure oil passage 21 on the discharge side of the oil pump 20 includes the secondary cylinder 10 and the line pressure control valve. 22, variable speed control valve 23
To the primary cylinder 9 via the oil passage 24 from the transmission speed control valve 23. The line pressure oil passage 21 further communicates with a regulator valve 25 via an orifice 32, and an oil passage 26 having a constant regulator pressure from the regulator valve 25 communicates with one of the solenoid valves 27, 28 and the speed change control valve 23. . The solenoid valves 27, 28 are, for example, turned on and exhausted by a duty signal from the control unit 40, and turned off to output the regulator pressure P _R , and generate such pulsed control pressure. The pulsed control pressure from the solenoid valve 27 is averaged by the accumulator 30 and acts on the line pressure control valve 22. On the other hand, the solenoid valve 28
The pulsed control pressure from the shift speed control valve 23
Acts on the other of. In the figure, reference numeral 29 is a drain oil passage, 31
Is an oil pan. The line pressure control valve 22 controls the line pressure P _L by the averaged control pressure from the solenoid valve 27. The speed change control valve 23 has a regulator pressure and a solenoid valve 28.
Due to the relationship of the pulsed control pressure from
It operates in a refueling position connecting 1, 24 and a draining position draining the line pressure oil passage 24. Then, the operating state at the two positions is changed according to the duty ratio to control the flow rate Q of oil supply or drain oil to the primary cylinder 9, and gear change control is performed at the gear change speed di / dt. The electronic control system will be described with reference to FIG. First, the speed change control system will be described. The speed change control system includes a primary pulley 7, a secondary pulley 8, rotation speed sensors 41, 42, 43 of the engine 1, and a throttle opening sensor 44.
Then, in the control unit 40, both pulley rotation speed sensors 4
The rotation speed signals Np and Ns from 1,42 are input to the actual gear ratio calculating section 45, and the actual gear ratio i is obtained by i = Np / Ns. Also,
The signal Ns from the secondary pulley rotation speed sensor 42 and the signal θ from the throttle opening sensor 44 are input to the target gear ratio search unit 46. Here, the gear shift pattern of the target gear ratio is is, for example, θ
-It is set by the table of Ns.
Is is searched for using the values of Ns and θ. This target gear ratio is
Is input to the target shift speed calculation unit 47, and
The target speed ratio change speed dis / dt is calculated from the change amount Δis. The actual speed ratio i of the actual speed ratio calculation unit 45, the steady target speed ratio is of the target speed ratio search unit 46, the target speed ratio change speed dis / dt and the coefficient setting unit of the target speed ratio calculation unit 47.
The coefficients k ₁ and k ₂ of 48 are input to the shift speed calculation unit 49, and the shift speed di / dt is calculated by di / dt = k ₁ (is-i) + k ₂ dis / dt. In the above formula of the speed change speed di / dt, the term k ₁ (is-i) is the control amount due to the deviation between the target speed change ratio is and the actual speed change ratio i,
If the operation amount is controlled to be the same as the control amount, the convergence is poor due to various delay elements of the control system of the continuously variable transmission.
Therefore, the target speed ratio change speed dis /
The so-called feedforward control is performed, in which the phase advance element of dt is obtained, and this is added to the above control amount in advance to determine the manipulated variable, whereby the delay component is absorbed and the convergence is improved. Become. The signals di / dt, i of the shift speed calculation unit 49 and the actual gear ratio calculation unit 45
Is further input to the duty ratio search unit 50. Here, due to the relationship of the duty ratio D = f (di / dt, i), di / dt and i
Table is set, and the duty ratio D is distributed to a value of 50% or more for shift up, and the value of the duty ratio D is 50% or less for shift down. Then, in the shift-up, the duty ratio D is set as a decreasing function with respect to i and is set as the increasing function with respect to | di / dt |
A decreasing function is set for / dt. Therefore, the duty ratio D is searched using this table. Then, the signal of the duty ratio D from the duty ratio searching unit 50 is input to the solenoid valve 28 via the driving unit 51. In the above control system, the throttle opening change speed detection unit 60 to which the throttle opening θ is input as correction means at the time of sudden acceleration
And the throttle opening change speed is calculated from dθ / dt. The throttle opening θ and its changing speed dθ / dt are input to the coefficient setting unit 48, and the coefficient K ₁ is changed by θ, dθ / dt. That is, in the term of K ₁ (is-i) related to the shift speed, the coefficient K ₁ is further set by K ₁ = f (θ, dθ / dt). Then, in the relationship of K ₁ -dθ / dt, as shown in FIG. 3, the coefficient K ₁ is set as an increasing function with respect to the throttle opening change rate dθ / dt. Further, regarding the relationship of K ₁ −θ, the value of the coefficient K ₁ is decreased according to the throttle opening degree θ at the start of accelerator depression, and thus the value of the coefficient K ₁ is changed by a map or the like. Next, the line pressure control system will be described. The signal θ of the throttle opening sensor 44 and the signal Ne of the engine speed sensor 43 are input to the engine torque calculation unit 52, and the engine torque T is obtained from the table of θ−Ne. . On the other hand, the required line pressure setting unit based on the actual gear ratio i from the actual gear ratio calculation unit 45.
At 53, the required line pressure P _LU per unit torque is obtained, and this and the engine torque T of the engine torque calculation unit 52 are input to the target line pressure calculation unit 54, and P _L = P _LU · T
The target line pressure P _L is calculated by. The output P _L of the target line pressure calculation unit 54 is the duty ratio setting unit
Input to 55 and the duty ratio D corresponding to the target line pressure P _L
To set. The signal of the duty ratio D is input to the solenoid valve 27 via the drive unit 56. Next, the operation of the control device for the continuously variable transmission configured as described above will be described. First, the power corresponding to the depression of the accelerator from the engine 1 is input to the primary pulley 7 of the continuously variable transmission 4 via the clutch 2 and the switching device 3, and the power shifted by the drive belt 11 and the secondary pulley 8 is output. Then, the vehicle travels by being transmitted to the drive wheels 16 side. While the vehicle is traveling, the target line pressure is set to be larger as the engine torque T is larger in a low speed stage where the value of the actual gear ratio i is large, and a corresponding signal having a large duty ratio is input to the solenoid valve 27 to control the pressure. Is generated to be small and the line pressure control valve 22 is operated with the averaged pressure to increase the line pressure P _L of the line pressure oil passage 21. As the gear ratio i becomes smaller and the engine torque T also becomes smaller, the duty ratio is reduced to increase the control pressure, so that the line pressure P _L is controlled so as to decrease due to the increase in the drain amount. A pulley pressing force corresponding to the transmission torque of the drive belt 11 acts. The line pressure P _L is always supplied to the secondary cylinder 10, and the shift speed is controlled by supplying and discharging the primary cylinder 9 by the shift speed control valve 23.
This will be explained below. First, the signals Np, Ns, θ from the sensors 41, 42 and 44 are read, the actual speed ratio i is calculated by the actual speed ratio calculating section 45 of the control unit 40, and the target speed ratio is is determined by the target speed ratio searching section 46. The target speed change ratio calculation unit 47 obtains the target speed change ratio change speed dis / dt, and the speed change speed calculation unit 49 uses these values and the coefficients K ₁ and K ₂ to change the speed change speed di / d.
Find t. Therefore, the duty ratio search unit 50 searches the duty ratio D using a table using di / dt and i. The duty signal is input to the solenoid valve 28 to generate a pulse-shaped control pressure, which causes the transmission speed control valve 23 to repeatedly operate at two positions of oil supply and oil discharge. Here, in the upshift, the pulsed control pressure by the solenoid valve 28 at a value of the duty ratio D ₀ or more that balances the oil supply and the oil drainage is such that the on-time zero pressure time is longer than the off-regulator pressure P _R time. As a result, the shift speed control valve 23 operates longer in the refueling position and refuels the primary cinder 9 to operate upshift. When | di / dt | is small, the difference between the duty ratios D and D ₀ is small, so the amount of oil supply is small and the shift speed is slow. However, as | di / dt | becomes larger, the difference between the duty ratios D and D ₀ becomes larger. Becomes larger,
The amount of refueling increases and the shifting speed becomes faster. On the other hand, in downshifting, the duty ratio that balances oil supply and oil discharge
Since the value is equal to or less than D ₀ , the control pressure is opposite to that described above, the shift speed control valve 23 has a longer operation time at the oil drain position, and the primary cinder 9 serves as oil drain to perform a downshift action. And in this case, di / dt By deviation D ₀ and the duty ratio D is smaller when the small, slow speed speed with a small oil discharge amount, the D ₀ and the duty ratio D as di / dt is large The deviation increases, the amount of oil drainage increases, and the gear shift speed increases. In this way, in the entire range of the low-speed stage and the high-speed stage, shifting up or down is performed while changing the shifting speed to continuously shift. Here, the shift speed control during acceleration will be described with reference to FIG. First, the accelerator is slowly depressed as shown by the solid line (throttle opening change speed dθ / dt) ≤ α (α
Is a set value), the coefficient K ₁ becomes a predetermined value. Therefore, the actual gear ratio i first follows the target gear ratio is based on θ−Ns mainly based on the deviation of K ₁ (is−i), and when the actual gear ratio i approaches the target gear ratio is K ₂・ The peak of the actual gear ratio i comes early due to the term of dis / dt and smoothly converges without overshooting. On the other hand, when (throttle opening change speed dθ / dt)> α due to sudden depression of the accelerator, the coefficient K is set by the coefficient setting unit 48.
The value of ₁ is set large corresponding to the throttle opening change speed dθ / dt. Therefore, the actual speed ratio i follows the target speed ratio is at a fast speed as shown by the broken line. At this time, the value of the target speed ratio change speed dis / dt also increases and the target speed ratio is shifts up as shown by the broken line, while the actual speed ratio i converges. Here, by the value of the coefficient K ₁ is reduced by the value of the throttle opening θ of when the accelerator depression start, the value of the coefficient K ₁ in the case of acceleration from the high opening degree does not become so large, low opening The coefficient K ₁ for acceleration from
The value of is greatly corrected. If you step on the accelerator abruptly,
The coefficient K ₁ is corrected with the throttle opening change speed dθ / dt after the time point of (throttle opening change speed dθ / dt)> α and the throttle opening θ at that time. Although one embodiment of the present invention has been described above, the present invention is not limited to this, and is applicable to a case where the engine speed is used as the target value.

【The invention's effect】

As described above, according to the present invention, the actual gear ratio converges to the target gear ratio at a high speed according to the deviation from the target gear ratio. The shift speed is increased and corrected according to the opening change speed, and at the same time, the shift speed is decreased and corrected according to the throttle opening when the throttle opening change speed exceeds a predetermined value. That is, the larger the throttle opening change speed corresponding to the accelerator pedal depression speed and the smaller the throttle opening at the start of the accelerator pedal depression, the faster the actual gear ratio converges to the target gear ratio at a larger gear speed. Therefore, it is possible to obtain an accurate acceleration response according to the level of the acceleration request.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a control device of the present invention, FIG. 2 is a block diagram of a control unit, FIG. 3 is a coefficient characteristic diagram, and FIG. 4 is a gear shift characteristic diagram during acceleration. . 4 ... Continuously variable transmission, 23 ... Shift speed control valve, 40 ... Control unit, 45 ... Actual speed ratio calculating unit, 46 ... Target speed ratio searching unit, 47 ...
Target shift speed calculation unit, 48 ... Coefficient setting unit, 49 ... Shift speed calculation unit, 60 ... Throttle opening change speed detection unit.

Claims (1)

[Claims] 1. A shift speed control is provided by a control signal output from a control unit, wherein a drive belt is wound between an input side pulley and an output side pulley whose pulley groove width is variably controlled by hydraulic pressure. In the continuously variable transmission that continuously changes the speed so that the actual speed ratio converges to the target speed ratio by controlling the supply and drain oil flow rate to the input side pulley via the valve, the control unit is The control unit has means for outputting a shift speed signal according to the deviation from the actual speed ratio, and the control unit has means for detecting a changing speed of the throttle opening corresponding to the depression amount of the accelerator pedal, and the detected throttle. When the opening change speed exceeds a predetermined value, the shift speed is increased and corrected as the throttle opening change speed increases, and the shift speed is decreased and corrected as the throttle opening at the start of accelerator depression increases. Control device for a continuously variable transmission, characterized in that a and stage.