JPH0659795B2 - Controller for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention

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 specifically, to a control device that controls a speed of change of a gear ratio (shift speed) as a control target. The present invention relates to an automatic gear shift control that emphasizes fuel efficiency and power performance. Regarding the shift control of this type of continuously variable transmission, for example, there is a basic hydraulic control system disclosed in Japanese Patent Laid-Open No. 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, primary pressure, 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, when shifting control of the continuously variable transmission, electronic control is performed in consideration of the speed of change of the gear ratio. Here, in the electronic control, a target gear ratio, a gear change speed, and an engine speed are set, and the target is controlled. Therefore, by setting these target values to those that place importance on fuel consumption efficiency and quietness, or those that place importance on power performance, it is possible to obtain arbitrary gear shifting characteristics.

[Prior art]

Therefore, conventionally, for the speed change control of the continuously variable transmission, for example, there is a prior art disclosed in Japanese Patent Laid-Open No. 59-212566. Here, it is shown that the larger the time change rate of the throttle opening according to the vehicle speed, the larger the shift speed is set, so that the gear shifts quickly when the acceleration is strong and shifts gently when the acceleration is weak. Has been done.

[Problems to be Solved by the Invention]

By the way, the above-mentioned prior art is a basic form of the acceleration control, which controls the shift so as to comply with the driver's intention to accelerate. Therefore, in order to emphasize power performance and fuel efficiency, various requirements must be added. Here, in the partial region where the throttle opening is smaller than full opening, the driving force can be arbitrarily adjusted by changing the engine torque according to the accelerator pedal depression amount. Therefore, even if the target gear ratio is set on the basis of the minimum fuel consumption rate, there is no problem in the power performance, and thus the fuel consumption-oriented gear shifting characteristic is possible. On the other hand, when the throttle opening is fully open, the driving force is determined by the engine torque and the gear ratio at that time, and when the desired acceleration cannot be obtained, the gear ratio is increased to increase the driving force and improve the power performance. It is necessary to improve. The present invention has been made in view of the above circumstances, and provides a control device for a continuously variable transmission capable of performing a shift control such that sufficient power performance can be obtained even in a shift characteristic with emphasis on fuel consumption. Is intended.

[Means for solving problems]

To achieve the above object, the present invention provides a continuously variable transmission in which a drive belt is wound between an input side primary pulley and an output side secondary pulley whose pulley groove widths are variably controlled by a hydraulic cylinder. Wrapping of the drive belt around the primary pulley and the secondary pulley by changing the primary pressure supplied to the hydraulic cylinder of the primary pulley through the speed change control valve output from the control unit. In a control device for a continuously variable transmission that continuously changes the diameter ratio to continuously change the speed, the control unit includes a primary pulley rotation speed sensor and a secondary pulley, which detect rotation speeds of the primary pulley and the secondary pulley, respectively. The actual gear ratio of the continuously variable transmission is calculated based on each detection signal of the rotation speed sensor. A gear ratio calculating unit, a target gear ratio searching unit that determines a target gear ratio corresponding to the minimum fuel consumption rate based on the detection signals of the secondary pulley rotation speed sensor and the throttle opening sensor, the target gear ratio and the actual gear ratio. Shift speed calculation unit that calculates the shift speed, the full-open determination unit that outputs the throttle full-open determination signal when it is determined that the throttle is fully open based on the detection signal of the throttle opening sensor, and the secondary pulley rotation speed sensor An acceleration detection unit that obtains the acceleration of the vehicle based on the detection signal of the vehicle and a driving force that outputs a gear ratio correction signal when it is determined that the driving force of the vehicle is insufficient by comparing the acceleration with a predetermined reference value. A determination unit and a correction unit that increases and corrects the target gear ratio based on the gear ratio correction signal and the throttle fully open determination signal. That.

[Action]

Based on the above configuration, in the partial region where the throttle opening is smaller than full open, the target value of the minimum fuel consumption rate is used for the fuel consumption-oriented shift control. Also, when the throttle opening is fully opened, it is determined whether the driving force is insufficient due to acceleration, and only when the acceleration is less than a predetermined value, the target value is corrected to compensate for the insufficient driving force and the power performance is fully demonstrated. Come to do. Thus, according to the present invention, it is possible to achieve both fuel efficiency performance in the partial range and power performance in the throttle fully open range, and it is possible to improve fuel efficiency and driving force as necessary.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be described. The engine 1 includes a main shaft 5 of a continuously variable transmission 4 via a clutch 2 and a forward / reverse switching device 3.
Connect to. In the continuously variable transmission 4, the auxiliary shaft 6 is arranged parallel to the main shaft 5, and the primary pulley 7 is attached to the main shaft 5.
Is provided with a secondary pulley 8, each pulley 7, 8 is equipped with hydraulic cylinders 9, 10 on the movable side, and a 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. An oil pump 20 driven by the engine 1 is provided, and a line pressure oil passage 21 on the discharge side of the oil pump 20 includes a secondary cylinder 10 and a line pressure control valve. 22 、 Shift speed control valve
It communicates with the primary cylinder 9 through the oil passage 24 from the transmission speed control valve 23. The line pressure oil passage 21 is further communicated with the regulator valve 25 via an orifice 32, and the oil passage 26 of a constant regulator pressure from the regulator valve 25 is
It communicates with one of the solenoid valves 27, 28 and the speed change control valve 23. Each solenoid valve 27, 28 is, for example, turned on and discharged by a duty signal from the control unit 40 and turned off to output a regulator pressure P _R , and generates such a 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 pulsed control pressure from the solenoid valve 28 acts on the other side of the shift speed control valve 23 as it is. In the figure, reference numeral 29 is a drain oil passage, and 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 the oil supply position where 1 and 24 are connected and the oil discharge position where the line pressure oil passage 24 is drained. The operation 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 shift speed control system will be described. The speed change control system includes a primary pulley 7, a secondary pulley 8, engine speed sensors 41, 42 and 43, and a throttle opening sensor 44. Then, in the control unit 40, the rotation signals N _p and N _s from the two pulley rotation speed sensors 41 and 42 are transmitted to the actual gear ratio calculation unit.
Input to 45, and obtain the actual gear ratio i by i = N _p / N _s . The signal N _s 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, where N _s − based on the gear shift pattern.
The target gear ratio is is searched from the table of θ. The signal θ of the throttle opening sensor 44 is input to the acceleration detection unit 51, the throttle opening change speed θ is calculated by the change of the throttle opening within a predetermined time, and the coefficient k is a function of θ in the coefficient setting unit 47 based on this. Is set as. Actual gear ratio calculator 45
Of the actual gear ratio i, the target gear ratio is of the target gear ratio searching unit 46 in the steady state, and the coefficient k of the coefficient setting unit 47 are
Then, the shift speed di / dt is calculated by di / dt = k (is-i), and if the sign is positive, shift down is determined, and if it is negative, shift up is determined. The signals di / dt, i of the speed change speed calculation unit 48 and the actual speed change ratio calculation unit 45
Is further input to the duty ratio search unit 49. Here, due to the relationship of the duty ratio D = f (di / dt, i), di / dt
And i are set, the duty ratio D is assigned to a value of 50% or more for shift up, and the duty ratio D is assigned to a value of 50% or less for shift down. In the upshift, the duty ratio D is set as a decreasing function with respect to i and is set as an increasing function with respect to | di / dt |, and in the downshift, the duty ratio D is conversely as an increasing function with respect to i and is set as di / dt. Is set with a decreasing function. Therefore, the duty ratio D is searched using this table. The signal of the duty ratio D from the duty ratio search unit 49 is input to the solenoid valve 28 via the drive unit 50. 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 θ−Ne
The engine torque T is obtained from the table. On the other hand, in the required line pressure setting unit 53 based on the actual gear ratio i from the actual gear ratio calculation unit 45, the required line pressure P _L u per unit torque is obtained.
And the engine torque T of the engine torque calculation unit 52 is input to the target line pressure calculation unit 54, and P _L = P _L
The target line pressure P _L is calculated from u · T. The output P _L of the target line pressure calculation unit 54 is input to the duty ratio setting unit 55 to set the duty ratio D corresponding to the target line pressure P _L. And the signal of this duty ratio D is
Input is made to the solenoid valve 27 via the drive unit 56. On the other hand, in the shift speed control system, in consideration of fuel consumption and power performance, the θ-N _s table of the target gear ratio search unit 46 is set based on the minimum fuel consumption rate, and determines the basic gear ratio with emphasis on fuel consumption. Further, the throttle opening signal θ from the sensor 44 is input to the fully open determination unit 60, and the throttle opening θ is fully opened θ.
_{It is} judged whether or not it is smaller than _wot , and divided into a fuel efficiency emphasis region of θ <θ _wot and a power performance correction region of θ ≧ θ _wot . Sensor 42
Secondary pulley rotation speed signal N according to vehicle speed from
_s is input to the acceleration detection unit 61, and the acceleration G is detected based on the difference between the vehicle speeds of the previous time and this time. The output G of the acceleration detection unit 61 is input to the driving force determination unit 62 and compared with a predetermined acceleration G _{1 which} is a constant value or a function of the vehicle speed to determine whether the driving force is insufficient. When G <G ₁ , it is determined that the driving force is insufficient and a gear ratio correction signal is output. A correction unit 63 is added to the output side of the target gear ratio search unit 46, and is + Δi is corrected by the full open signal of the full open determination unit 60 and the gear ratio signal of the driving force determination unit 62. Δi is a corrected gear ratio, and when G <G ₁ , increases by Δi = Δi + Δi ′ and continues increasing until G ≧ G ₁ . This allows
As shown in FIG. 4, the driving force is increased by shifting gears in a correction shift line ₂ that is downshifted by Δi with respect to the throttle opening line ₁ . Further, in order to determine the limit of correction of the gear ratio, a maximum driving force calculation unit 64 to which the N _s signal is input is provided, and the vehicle speed V of FIG.
_{At 1} , the gear ratio imax that produces the maximum driving force is calculated. The maximum gear ratio imax of the maximum driving force calculation unit 64 and the gear ratio correction is + Δi of the driving force determination unit 62 are input to the correction limit determination unit 65, and when imax ≦ is + Δi, even if G <G ₁ , the increase of Δi does not occur. Stop and limit corrections. From this, as shown in FIG. 4, when the acceleration G is insufficient for the corrected shift line _2, it is possible to further shift to the maximum driving force line ₃ . 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. This is the drive wheel 16
It travels by transmitting to the 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 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 decreased 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 constantly supplied to the secondary cylinder 10, and the shift speed is controlled by supplying and discharging oil to the primary cylinder 9 by the shift speed control valve 23, which will be described below. First, the signals N _p , N _s , θ from the respective sensors 41, 42 and 44.
Is read, and the actual gear ratio calculation unit 45 of the control unit 40 obtains the actual gear ratio i, and the target gear ratio search unit 46 obtains the target gear ratio is,
Using these and the coefficient k, the shift speed calculation unit 48 shifts the shift speed di
Calculate / dt. Therefore, when the shift ratio is is <i and the shift ratio is is> i, the duty ratio search unit 49 uses a table according to di / dt and i.
Will be searched. 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 shift-up, pulsed control pressure by the solenoid valve 28 at a duty ratio greater than or equal to D which lubrication and the oil discharge is balance, it between zero pressure time of ON is longer than the regulator pressure P _R off time The operation speed of the speed change control valve 23 at the oil supply position becomes longer, and the primary cylinder 9 is supplied with oil more than the oil drained to operate upshift. When | di / dt | is small on the low gear side where i is large, the value of D is small, so the amount of oil supply is small and the shift speed is slow.
The value of D increases as the value of | di / dt | increases, and the amount of oil supply increases and the speed of shifting increases. On the other hand, in the downshift, the control pressure is opposite to the above because the duty ratio D is equal to or less than the balance between the oil supply and the oil discharge, and the shift speed control valve 23 has a long operating time at the oil discharge position. The primary cylinder 9 serves as a drainage oil in addition to the lubrication oil and acts as a downshift. In this case, when di / dt is small on the low speed side where i is large, the value of D is large, so the amount of oil drain is small and the shift speed is slow, and the speed shifts to the high speed side where i is small. As the value of dt increases, the value of D decreases, the amount of oil discharged increases, and the 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. Next, in the above shift speed control, the operation when the throttle opening is smaller than full open and when it is full open will be described with reference to the flowchart in FIG. First, the throttle opening θ is determined by the fully open determination unit 60, and θ
In the partial region of <θwot, the function of the correction unit 63 is stopped, and the target gear ratio is based on the minimum fuel consumption rate of the target gear ratio search unit 46 is input to the gear shift speed calculation unit 48, and gear shift control is performed.
Therefore, gear shifting is performed on the side where the engine speed is lower than the throttle fully open line ₁ in FIG. On the other hand, when the throttle is fully opened, the full-open signal of the full-open determination unit 60 is input to the correction unit 63 so that the correction can be performed. At this time, the acceleration detection unit 61 and the driving force determination unit 62 determine the driving force based on the acceleration. If G ≧ G ₁ , the driving force is determined to be sufficient and the correction amount Δi = 0, and Shifting will be done with the throttle fully open line ₁ . On the other hand, when G <G _1, the correction unit 63 increases Δi by Δi ′ by the correction signal from the driving force determination unit 62 to perform correction of is + Δi. The gear shift line is shifted to the side where the engine speed is higher as shown by line ₂ in FIG. 4 to increase the driving force. When G ≧ G ₁ , the correction signal from the driving force determination unit 62 stops, Δi does not increase, and the shift line is held in this state. At the time of correcting the gear ratio, the maximum driving force calculation unit 64 calculates the maximum gear ratio imax of each vehicle speed, and the correction limit determination unit 65
The correction limit is checked in. So G <G ₁ with ima
When x ≦ is + Δi, the limit signal of the correction limit determination unit 65 limits is = imax. Therefore, the gear shift is performed along the maximum driving force line ₃ in FIG. Although one embodiment of the present invention has been described above, it can be similarly applied to a case where the engine speed or the like is used as the target value.

【The invention's effect】

As described above, according to the present invention, the shift control is performed with emphasis on the fuel consumption in the partial region where the driving force changes due to the depression of the accelerator, so that the fuel consumption is improved. When the throttle is fully open, the driving force is increased due to the shift-down correction, which improves power performance. Since it is determined by acceleration whether or not the driving force is insufficient, acceleration performance can be improved. Since the maximum gear ratio is calculated and the upper limit is set,
It is possible to maximize the driving force.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hydraulic control system in an embodiment of a control device of the present invention, and FIG. 2 is a block diagram showing an electronic control system.
FIG. 3 is a flow chart for explaining the operation, and FIG. 4 is a diagram showing shift characteristics. 4 ... Continuously variable transmission, 40 ... Control unit, 44 ... Throttle opening sensor, 46 ... Target gear ratio search unit, 60 ... Full open determination unit, 61
... acceleration detection unit, 62 ... driving force determination unit, 63 ... correction unit.

Claims (1)

[Claims] 1. A continuously variable transmission in which a drive belt is wound between an input-side primary pulley and an output-side secondary pulley whose pulley groove widths are variably controlled by hydraulic cylinders. The primary pressure to be supplied to the hydraulic cylinder is changed via the speed change control valve by the speed change control signal output from the control unit to continuously change the winding diameter ratio of the drive belt to the primary pulley and the secondary pulley. In the control device for a continuously variable transmission that changes the speed to a continuously variable speed, the control unit detects the primary pulley rotation speed sensor and the secondary pulley rotation speed sensor that detect the rotation speeds of the primary pulley and the secondary pulley, respectively. An actual speed ratio calculating section that calculates the actual speed ratio of the continuously variable transmission based on the signal; A target speed ratio search unit that determines the target speed ratio corresponding to the minimum fuel consumption rate based on the detection signals of the secondary pulley speed sensor and the throttle opening sensor, and the speed change speed is calculated from the deviation between the target speed ratio and the actual speed ratio. The shift speed calculation unit, the full-open determination unit that outputs a throttle full-open determination signal when it is determined that the throttle is fully open based on the detection signal from the throttle opening sensor, and the vehicle acceleration based on the detection signal from the secondary pulley rotation speed sensor. An acceleration detection unit that determines the driving force, a driving force determination unit that outputs a gear ratio correction signal when it is determined that the driving force of the vehicle is insufficient by comparing the acceleration with a predetermined reference value, and the gear ratio correction A control device for a continuously variable transmission, comprising: a correction unit that increases and corrects the target gear ratio based on a signal and a throttle full-open determination signal. .