JP2010210070A - Control device for continuously variable transmission - Google Patents

Abstract

There is provided a control device for a continuously variable transmission capable of improving followability when an actual speed ratio of a continuously variable transmission is made to follow a target speed ratio.
A command pressure Pin for setting an actual gear ratio Rγ of a continuously variable transmission 4 to a target gear ratio Tγ is calculated based on a feedforward pressure Pinff and a feedback pressure Pinfb. When individual differences, aging deterioration, etc. occur in the continuously variable transmission 4, the steady deviation between the actual speed ratio Rγ and the target speed ratio Tγ can be eliminated by increasing or decreasing the feedback pressure Pinfb. It is. When the feedback pressure Pinfb is away from the initial value “0” during the steady operation of the continuously variable transmission 4, the feedback pressure Pinfb is a learning value G (i) that becomes a value corresponding to the steady deviation. After that, the learning value G (i) is reflected on the feedforward pressure Pinff.
[Selection] Figure 1

Description

  The present invention relates to a control device for a continuously variable transmission.

  In a vehicle such as an automobile, a belt is used as a transmission for changing a transmission gear ratio, which is a ratio of a rotation speed on the wheel side and a rotation speed on the internal combustion engine side, on a rotation transmission path between the internal combustion engine and the wheel. A type in which a continuously variable transmission of the type is provided is known.

  Such a continuously variable transmission includes a primary pulley and a secondary pulley around which a belt is wound, and adjusts a gear ratio through adjustment of hydraulic pressure acting on the pulleys. Of the primary pulley and the secondary pulley, the secondary pulley sandwiches the belt so as not to slip due to thrust generated through the action of the hydraulic pressure. The primary pulley is driven by thrust generated through the action of the hydraulic pressure to change the distance from the rotation center of the pulley to the belt, thereby adjusting the transmission ratio of the continuously variable transmission. The adjustment of the gear ratio in the continuously variable transmission is specifically calculated by calculating a command pressure for setting the actual gear ratio of the continuously variable transmission to the target gear ratio, and based on the calculated command pressure. This is realized by adjusting the hydraulic pressure acting on the primary pulley.

  When calculating the command pressure for adjusting the hydraulic pressure acting on the primary pulley, for example, as disclosed in Patent Document 1, it is calculated as a value corresponding to the hydraulic pressure required for realizing the target gear ratio. Feed forward pressure is used. However, even if the hydraulic pressure acting on the primary pulley is adjusted based on the command pressure thus calculated, the actual gear ratio of the continuously variable transmission may not necessarily be the target gear ratio. This is because it is inevitable that individual differences and aging deterioration occur in the continuously variable transmission, and the calculated command pressure is a value that makes the actual gear ratio the target gear ratio by the amount of such individual differences and aging deterioration. This is because it deviates from the appropriate value.

  Further, Patent Document 1 discloses that feedback control of hydraulic pressure acting on the primary pulley is performed so that the actual transmission ratio of the continuously variable transmission becomes the target transmission ratio. Such feedback control may be performed as follows, for example. That is, when calculating the command pressure of the hydraulic pressure acting on the primary pulley, the calculation is performed using not only the feedforward pressure but also the feedback pressure, and the actual transmission ratio of the continuously variable transmission and the target transmission ratio are calculated. Based on the deviation, the feedback pressure is increased or decreased so that the deviation approaches “0”. By calculating the indicated pressure using the feedback pressure that is increased or decreased in this way, and adjusting the hydraulic pressure acting on the primary pulley based on the indicated pressure, it is indicated by the individual difference of the continuously variable transmission, aging deterioration, etc. Even when the pressure is likely to deviate from an appropriate value, the deviation can be eliminated by increasing or decreasing the feedback pressure.

JP 2005-315374 A (paragraphs [0020] to [0030], [0004], [0005])

  As described above, by calculating the command pressure based on the feedforward pressure and the feedback pressure, the command pressure targets the actual gear ratio of the continuously variable transmission by the amount of individual differences of the continuously variable transmission, aging deterioration, etc. Deviation from an appropriate value for obtaining the gear ratio is suppressed, and deviation of the actual gear ratio from the target gear ratio is suppressed by the above-described individual differences and aging deterioration. Note that the deviation of the actual gear ratio from the target gear ratio due to individual differences in the continuously variable transmission or aging deterioration is steady, and when the steady deviation disappears through the increase or decrease of the feedback pressure, the feedback pressure Is converged to a value corresponding to the steady deviation.

  However, since the target gear ratio varies greatly depending on the driving state of the vehicle, etc., if the feedback pressure is increased or decreased so that the actual gear ratio becomes the above-mentioned target gear ratio that varies, the feedback pressure also varies greatly. The feedback pressure that fluctuates greatly in this way is a value that is difficult to quickly converge to a value that corresponds to a steady deviation of the actual gear ratio with respect to the target gear ratio due to individual differences in the continuously variable transmission or aging deterioration. Therefore, it is inevitable that the convergence to the value corresponding to the steady deviation is delayed. Therefore, the amount of follow-up in causing the actual speed ratio of the continuously variable transmission to follow the fluctuating target speed ratio is reduced by the amount of delay in convergence to the value corresponding to the steady deviation in the feedback pressure.

  The present invention has been made in view of such circumstances, and an object thereof is a continuously variable transmission capable of improving the followability when the actual speed ratio of the continuously variable transmission follows the target speed ratio. It is to provide a control device.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, one of the primary pulley and the secondary pulley around which the belt is wound is hydraulically driven to change the distance from the rotation center of the pulley to the belt. Is applied to a continuously variable transmission whose speed ratio is adjusted, and calculates the command pressure of the hydraulic pressure for setting the actual speed ratio of the continuously variable transmission as a target speed ratio, and the pulley is based on the commanded pressure. In the control device of the continuously variable transmission that adjusts the hydraulic pressure acting on the feed pressure, the command pressure is calculated as the hydraulic pressure required to realize the target gear ratio, the actual gear ratio, and the A calculation means for calculating based on feedback pressure that increases or decreases the deviation so as to approach “0” based on a deviation from the target gear ratio, and a state in which the input rotational speed of the continuously variable transmission is constant Learning means for storing the feedback pressure as a learning value on condition that the absolute value of the feedback pressure is equal to or greater than a predetermined determination value when the operation lasts long enough to be determined as steady operation; and the stored learning And a reflecting means for reflecting the value in the feedforward pressure when the indicated pressure is calculated by the calculating means.

  The adjustment to the target gear ratio of the actual transmission in the continuously variable transmission is performed by calculating a target pressure based on the feedforward pressure and the feedback pressure and adjusting the hydraulic pressure acting on the primary pulley based on the target pressure. Regarding the effects of individual differences in continuously variable transmissions, aging deterioration, etc., there is an increase or decrease in the value required to realize the target gear ratio of the calculated feedforward pressure, and an instruction calculated based on the feedforward pressure It appears that the pressure becomes a value deviated from an appropriate value for setting the actual transmission ratio of the continuously variable transmission as the target transmission ratio. Such a deviation from the appropriate value of the command pressure is suppressed by increasing or decreasing the feedback pressure used to calculate the command pressure so that the deviation approaches “0” based on the deviation between the actual transmission and the target gear ratio. . When it is determined that the operation is steady, the feedback pressure that is increased or decreased as described above converges to a value corresponding to the steady deviation of the actual transmission ratio with respect to the target transmission ratio due to individual differences in the continuously variable transmission or aging degradation. It will be in the state.

  If the indicated pressure is adjusted to an appropriate value only by increasing / decreasing the feedback pressure, and the steady shift of the actual gear ratio with respect to the target gear ratio due to individual differences in the continuously variable transmission or aging deterioration is suppressed, The following problems are unavoidable. In other words, when the target speed ratio changes greatly, the feedback pressure also changes greatly so that the actual speed ratio becomes the above-described changing target speed ratio, but the feedback pressure that fluctuates greatly to a value corresponding to the steady deviation. It is a value that is difficult to converge quickly, and the convergence is delayed. As a result of the delay in convergence to the value corresponding to the steady deviation in the feedback pressure, the followability when the actual speed ratio of the continuously variable transmission is made to follow the fluctuating target speed ratio decreases.

  According to the above configuration, when the steady operation is determined, the feedback value is stored as a learning value on condition that the feedback pressure is equal to or higher than the determination value. The learning value stored in this manner is a value corresponding to the above-described steady deviation of the actual transmission ratio of the continuously variable transmission with respect to the target transmission ratio. After the learned value is stored as a value corresponding to the steady deviation, the stored learned value is always reflected in the feedforward pressure, and the indicated pressure is based on the feedforward pressure in which the learned value is reflected. Is calculated as a value that can eliminate the steady deviation. Therefore, by adjusting the hydraulic pressure acting on the primary pulley based on the command pressure calculated in this way, the above-described problem occurs even if the target gear ratio fluctuates greatly, that is, continuously with respect to the target gear ratio. Occurrence of a problem that the followability when the actual transmission ratio of the transmission is followed is reduced is suppressed. Thereby, the followability | trackability at the time of making the actual gear ratio of a continuously variable transmission follow a target gear ratio can be improved.

  The invention according to claim 2 is the invention according to claim 1, wherein the secondary pulley of the primary pulley and the secondary pulley sandwiches the belt so as not to slip due to a thrust generated through the action of hydraulic pressure, The primary pulley is driven by thrust generated through the action of hydraulic pressure adjusted based on the command pressure, and changes the distance from the rotation center of the pulley to the belt. The feedforward pressure is the thrust of the secondary pulley. And the thrust of the primary pulley, which is calculated based on the thrust ratio, which is a value representing the ratio when the actual speed ratio can be maintained at the target speed ratio during steady operation, The ratio is the minimum necessary to prevent slippage of the belt in the actual thrust of the secondary pulley. Based on safety factors, and the target gear ratio represents a margin for the value, and shall be calculated.

  The influence due to individual differences of the continuously variable transmission, aging deterioration, etc. appears, for example, in the form of deviation between the actual value and the calculated value in the thrust ratio. In this case, the feedforward pressure calculated based on the thrust ratio becomes a value that is too large or too small relative to the value required to achieve the target gear ratio, and the command pressure calculated based on the feedforward pressure is continuously variable. The actual transmission ratio of the transmission is a value deviated from an appropriate value for setting the target transmission ratio. As a result, the effects of individual differences in the continuously variable transmission, aging deterioration, and the like are such that the actual gear ratio in the continuously variable transmission when the hydraulic pressure acting on the primary pulley is adjusted based on the indicated pressure is steady with respect to the target gear ratio. Appears as a gap. According to the above configuration, the learning value is stored as a value corresponding to such a steady deviation, and thereafter the learning value is always reflected in the feedforward pressure. Then, by calculating the command pressure based on the feedforward pressure in which the learned value is reflected, the command pressure is calculated as a value that can eliminate the steady deviation. Therefore, by adjusting the hydraulic pressure acting on the primary pulley based on the command pressure calculated in this way, even if the target gear ratio fluctuates greatly, the actual gear ratio of the continuously variable transmission follows the target gear ratio. The followability at the time of making it can be improved.

  According to a third aspect of the present invention, in the second aspect of the present invention, the learning value is prepared for each of a plurality of learning regions partitioned based on the target gear ratio and the safety factor, and the learning means When the state in which the input rotational speed of the step transmission is constant continues for a long time so that it can be determined as steady operation, the feedback pressure is currently set on condition that the absolute value of the feedback pressure is greater than or equal to a predetermined determination value. Stored as a learning value of a learning area corresponding to the target speed ratio and safety factor of the target, and the reflection means learns corresponding to the current target speed ratio and safety factor when the instruction pressure is calculated by the calculation means. The gist is to reflect the learning value of the region in the feedforward pressure.

  Since the effects of individual differences in continuously variable transmissions and aging deterioration vary depending on the target gear ratio and safety factors, the steady shift of the actual gear ratio in the continuously variable transmission due to the above effects to the target gear ratio is also the target speed change. It depends on the ratio and safety factor. According to the above configuration, a learning value is prepared for each of a plurality of learning areas partitioned based on the target gear ratio and safety factor, and these learning values are stored for each learning area as values corresponding to the steady deviation. The Then, the learning value in the learning region corresponding to the current target speed ratio and safety factor is reflected in the feedforward pressure, and the command pressure used for adjusting the hydraulic pressure acting on the primary pulley is calculated based on the feedforward pressure. For this reason, when the current target gear ratio and safety factor change from a predetermined learning region to another learning region, the learning value reflected in the feedforward pressure corresponding to the predetermined learning region also changes from the one corresponding to the predetermined learning region. Switch to one corresponding to another learning area. Therefore, even if the current target gear ratio and safety factor change as described above, and the influence on the steady deviation of the actual gear ratio with respect to the target gear ratio due to individual differences in the continuously variable transmission and aging deterioration, etc. By calculating the command pressure based on the feedforward pressure, the command pressure is calculated to be a value that can accurately eliminate the steady deviation.

  According to a fourth aspect of the invention, in the third aspect of the invention, when the number of areas where the learning value is stored is counted among the plurality of learning areas, and the counted value is equal to or greater than a determination value. And a stop means for stopping the increase and decrease of the feedback pressure.

  If learning values are stored in a certain number of learning regions among all of the plurality of learning regions, it is possible to improve followability when following the actual gear ratio of the continuously variable transmission with respect to the target gear ratio. The above-described effect can be obtained. According to the above configuration, when the learning value is stored and the learning area is increased and the above effect is obtained, the calculation means for calculating the command pressure by stopping the increase / decrease in the feedback pressure is used. The load can be reduced.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the stop means adjusts the hydraulic pressure acting on the primary pulley based on the command pressure while the increase / decrease of the feedback pressure is stopped. When it is determined that overshoot, undershoot, or hunting of the actual speed ratio with respect to the target speed ratio has occurred when the speed ratio is set as the target speed ratio, the counted value is reset to the initial value “0”. In addition, the gist is to cancel the stop of the increase / decrease of the feedback pressure and to resume the increase / decrease.

  While the feedback pressure increase / decrease is stopped, the steady-state deviation of the actual transmission ratio of the continuously variable transmission from the target gear ratio changes, such as the deterioration of the continuously variable transmission progresses and the influence of the same age deterioration increases. The stored learning value becomes an inappropriate value as a value corresponding to the steady deviation. In this case, even if the command pressure is calculated based on the feedforward pressure in which the learned value is reflected, the command pressure does not become a value that can eliminate the steady deviation. For this reason, when the hydraulic pressure acting on the primary pulley is adjusted based on the command pressure to set the actual gear ratio to the target gear ratio, there is a risk that overshoot, undershoot, or hunting of the actual gear ratio with respect to the target gear ratio may occur. . According to the above configuration, when it is determined that such overshoot, undershoot, or hunting has occurred, the increase / decrease of the feedback pressure is resumed, and the learning value is stored again in each learning region. Therefore, even if the steady deviation of the actual transmission ratio of the continuously variable transmission with respect to the target transmission ratio changes while the feedback pressure increase / decrease is stopped, the learning value is a value corresponding to the steady deviation after the change. Can be stored again as an appropriate value.

Schematic which shows the drive system of the motor vehicle to which the control apparatus of 1st Embodiment is applied. The hydraulic circuit diagram of the part which drives the continuously variable transmission in a hydraulic control circuit. The flowchart which shows the memory | storage procedure of a learning value. A table showing learning areas. The flowchart which shows the calculation procedure of instruction | indication pressure. (A)-(d) is a flowchart which shows transition of an input rotational speed, a feedback pressure, feedforward pressure, and a gear ratio. The flowchart which shows the memory | storage procedure of the learning value in 2nd Embodiment. The time chart which shows transition of the actual gear ratio and target gear ratio of a continuously variable transmission. The time chart which shows transition of the actual gear ratio and target gear ratio of a continuously variable transmission.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in a belt-type continuously variable transmission mounted on an automobile will be described with reference to FIGS.

  As shown in FIG. 1, in the driving system of an automobile, the rotation of the engine 1 is transmitted to the wheels via a torque converter 2, a forward / reverse switching device 3, a continuously variable transmission (CVT) 4, and the like. It becomes.

  In the engine 1, the opening degree of the throttle valve 6 (throttle opening degree) provided in the intake passage 5 is such that the depression amount (accelerator depression amount) of the accelerator pedal 7 that is operated by the driver of the automobile. Control is performed in response to an output request to the engine 1. The intake air amount of the engine 1 is adjusted by the throttle opening control, and fuel injection corresponding to the intake air amount is performed by the fuel injection valve 13. Then, the amount of the air-fuel mixture consisting of fuel and air filled in the combustion chamber of the engine 1 is adjusted, thereby changing the engine output. Therefore, control of the engine output is realized by adjusting the intake air amount through the opening degree control of the throttle valve 6.

  The torque converter 2 includes a pump impeller 8 connected to a crankshaft 1 a that is an output shaft of the engine 1, and a turbine impeller 10 connected to a forward / reverse switching device 3 and a continuously variable transmission 4 via a turbine shaft 9. The rotation transmission between the pump impeller 8 and the turbine impeller 10 is performed via a fluid. An oil pump 11 is connected to the pump impeller 8. The oil pump 11 is driven based on the rotation of the pump impeller 8 (engine rotation), and discharges oil for hydraulically driving the continuously variable transmission 4 and operating the forward / reverse switching device 3. The oil discharge pressure of the oil pump 11 increases as the engine speed increases.

  The forward / reverse switching device 3 switches the direction of input rotation from the turbine shaft 9 with respect to the input shaft 4a of the continuously variable transmission 4 between the forward rotation direction and the reverse rotation direction, or the turbine shaft 9 to the input shaft 4a. The rotation input from is cut off. The operation of the forward / reverse switching device 3 is performed based on the oil discharge pressure of the oil pump 11 based on the operation of the shift lever 28 by the driver of the automobile.

  The continuously variable transmission 4 is provided on a rotation transmission path between the engine 1 and the wheel in the drive system of the automobile, and changes a gear ratio that is a ratio of the rotation speed on the wheel side and the rotation speed on the engine 1 side. It is driven as much as possible. Such a continuously variable transmission 4 includes a primary pulley 18 provided on the input shaft 4a, a secondary pulley 19 provided on the output shaft 4b, and a belt 20 wound around the pulleys 18 and 19. Adjustment of the gear ratio in the continuously variable transmission 4 is realized by adjusting the hydraulic pressure acting on the primary pulley 18 and the secondary pulley 19 through the hydraulic control circuit 21.

  The secondary pulley 19 of the continuously variable transmission 4 sandwiches the belt 20 so that the belt 20 does not slip with respect to the pulleys 18 and 19 due to the thrust generated in the center line direction of the pulley 19 through the action of the hydraulic pressure. Specifically, the secondary pulley 19 includes a fixed sheave 19a and a movable sheave 19b. By causing the hydraulic pressure to act on the movable sheave 19b, the movable sheave 19b is caused to generate a thrust in the center line direction, and the movable sheave 19b. And the fixed sheave 19a so that the belt 20 is not slipped against the pulleys 18 and 19.

  The primary pulley 18 is driven in the direction of the center line by a thrust generated in the direction of the center line of the pulley 18 through the action of the hydraulic pressure. Specifically, the primary pulley 18 includes a fixed sheave 18a and a movable sheave 18b. By causing the hydraulic pressure to act on the movable sheave 18b, the movable sheave 18b is caused to generate a thrust in the direction of the center line, thereby moving the movable sheave 18b. Is moved toward and away from the fixed sheave 18a with the belt 20 interposed therebetween. Through such driving of the primary pulley 18, the distance from the rotation center of the pulley 18 to the belt 20 is changed, thereby adjusting the gear ratio in the continuously variable transmission 4.

Here, the detail of the part which drives the continuously variable transmission 4 in the hydraulic control circuit 21 is demonstrated with reference to FIG.
In the hydraulic control circuit 21, the oil discharged from the oil pump 11 is supplied to the oil passage 31. The oil passage 31 supplies oil to the primary pulley 18 of the continuously variable transmission 4 to apply hydraulic pressure to the pulley 18, and supplies oil to the secondary pulley 19 of the continuously variable transmission 4 to supply the pulley 19 with oil. In contrast, the hydraulic pressure is applied.

  The hydraulic control circuit 21 is provided with a primary regulator valve 32 that regulates the oil discharge pressure of the oil pump 11 to a line pressure that is a hydraulic pressure used for hydraulic drive of the continuously variable transmission 4 and the like. Further, the hydraulic pressure control circuit 21 adjusts the primary pulley control valve 35 that adjusts the hydraulic pressure acting on the primary pulley 18 based on the line pressure, and the hydraulic pressure that acts on the secondary pulley 19 based on the line pressure. A secondary pulley control valve 33 is provided. The primary pulley control valve 35 is driven and controlled using hydraulic pressure by the linear solenoid valve 36, and the secondary pulley control valve 33 is driven and controlled using hydraulic pressure by the linear solenoid valve 34.

  Regarding the adjustment of the hydraulic pressure acting on the secondary pulley 19, through the drive control of the linear solenoid valve 34, the thrust generated in the direction of the center line of the pulley 19 (FIG. 1) based on the action of the hydraulic pressure is applied to the belt 20 and the pulleys 18, 19. The value is set so as not to cause slippage between the two. Further, regarding the adjustment of the hydraulic pressure acting on the primary pulley 18, through the drive control of the linear solenoid valve 36, the thrust generated in the direction of the center line of the pulley 18 (FIG. 1) based on the hydraulic pressure action is a desired gear ratio (target The transmission ratio is set to a value that can be realized. For example, when changing the gear ratio to the low side, the hydraulic pressure acting on the pulley 18 is made small so that the thrust of the primary pulley 18 becomes small, and when changing the gear ratio to the high side, The hydraulic pressure acting on the pulley is increased so that the thrust of the primary pulley 18 is increased.

Next, the electrical configuration of the automobile control apparatus in the present embodiment will be described with reference to FIG.
The control device includes an engine control computer 25 that controls the operation of the engine 1. The engine control computer 25 is connected to a transmission control computer 26 for controlling the forward / reverse switching device 3 and controlling the hydraulic control circuit 21 to hydraulically drive the continuously variable transmission 4 so that they can communicate with each other. Yes.

  The engine control computer 25 receives a detection signal from the accelerator position sensor 27 that detects the amount of depression of the accelerator pedal 7 (accelerator depression amount) and a detection signal from the throttle position sensor 12 that detects the opening of the throttle valve 6. Is done. The engine control computer 25 adjusts the intake air amount of the engine 1 by controlling the opening of the throttle valve 6 based on the accelerator depression amount and the like, and a fuel injection valve so that an amount of fuel corresponding to the intake air amount is injected. 13 is driven to control the fuel injection amount. In the engine 1, the engine output is adjusted through the adjustment of the intake air amount by controlling the opening degree of the throttle valve 6.

  On the other hand, the transmission control computer 26 receives a detection signal from the hydraulic sensor 16 that detects the hydraulic pressure acting on the secondary pulley 19, position information corresponding to the operation position of the shift lever 28, and the like. Further, the transmission control computer 26 receives a detection signal from the input rotational speed sensor 29 for detecting the input rotational speed of the continuously variable transmission 4 (the rotational speed of the input shaft 4a), and the output rotational speed of the continuously variable transmission 4 ( A detection signal from the output rotation speed sensor 30 for detecting the rotation speed of the output shaft 4b is also input. The transmission control computer 26 drives the continuously variable transmission 4 and the forward / reverse switching device 3 through the control of the hydraulic control circuit 21.

Next, hydraulic control for driving the continuously variable transmission 4 will be described.
In such hydraulic control, adjustment of the hydraulic pressure acting on the secondary pulley 19 for suppressing slippage of the belt 20 with respect to the pulleys 18 and 19 and adjustment of the hydraulic pressure acting on the primary pulley 18 for realizing the target gear ratio are performed. .

  The hydraulic pressure acting on the secondary pulley 19 is adjusted based on the command pressure TPout of the hydraulic pressure. This command pressure TPout is based on a target thrust TWout that is a target value of the thrust of the secondary pulley 19 and a pressure receiving area Aout of the pulley 19 (movable sheave 19b) that receives the hydraulic pressure acting on the pulley 19, according to the following formula ( 1).

TPout = TWout / Aout (1)
TPout: Indicating hydraulic pressure acting on the secondary pulley
TWout: Secondary thrust target thrust
Aout: pressure receiving area of secondary pulley The target thrust TWout in the equation (1) is the estimated input torque Tt that is an estimated value of the torque input to the input shaft 4a of the continuously variable transmission 4, and the actual transmission of the continuously variable transmission 4. Based on the speed ratio Rγ, the value is calculated so as not to cause slippage between the belt 20 and the pulleys 18 and 19. The estimated input torque Tt used here is obtained based on the throttle opening of the engine 1, and the actual gear ratio Rγ is based on the output rotational speed Nout of the continuously variable transmission 4 and the input rotational speed Nin (Nout / Nin). Then, by adjusting the hydraulic pressure acting on the secondary pulley 19 based on the command pressure TPout calculated using the equation (1), the slip of the belt 20 with respect to the pulleys 18 and 19 is suppressed.

  On the other hand, the hydraulic pressure acting on the primary pulley 18 is adjusted based on the hydraulic pressure command pressure Pin for setting the actual gear ratio Rγ of the continuously variable transmission 4 to the target gear ratio Tγ. Incidentally, the target speed ratio Tγ of the continuously variable transmission 4 is set, for example, as the speed ratio at which the fuel consumption of the engine 1 is optimal based on the position of the shift lever 28, the accelerator depression amount, the vehicle speed, and the like. The vehicle speed is determined based on the output rotation speed Nout. The command pressure Pin is calculated based on the feedforward pressure Pinff calculated as the hydraulic pressure required for realizing the target gear ratio Tγ and the deviation Δγ between the actual gear ratio Rγ and the target gear ratio Tγ. Is calculated using the following equation (2) based on the feedback pressure Pinfb that increases or decreases to decrease.

Pin = Pinff + Pinfb (2)
Pin: Indicating hydraulic pressure acting on the primary pulley
Pinff: Feed forward pressure
Pinfb: Feedback pressure By adjusting the hydraulic pressure acting on the primary pulley 18 based on the command pressure Pin calculated using the equation (2), the pulley 18 is driven and the rotation center of the pulley 18 to the belt 20 is driven. The distance is adjusted, whereby the actual speed ratio Rγ of the continuously variable transmission 4 is set to the target speed ratio Tγ.

  If the command pressure Pin is calculated only from the feedforward pressure Pinff, the actual gear ratio Rγ cannot be set to the target gear ratio Tγ when the hydraulic pressure acting on the primary pulley 18 is adjusted based on the command pressure Pin. there is a possibility. This is inevitable that individual differences and aging degradation occur in the continuously variable transmission 4, and the calculated command pressure Pin (= feed-forward pressure Pinff) is actualized only by such individual differences and aging degradation. This is because the gear ratio Rγ deviates from an appropriate value as the target gear ratio Tγ.

  However, by calculating the command pressure Pin as shown in the equation (2), the actual speed ratio Rγ can be set to the target speed ratio Tγ with only the feedforward pressure Pinff due to individual differences of the continuously variable transmission 4 or aging deterioration. If this is not possible, the deviation of the command pressure Pin from the appropriate value can be eliminated by increasing or decreasing the feedback pressure Pinfb based on the deviation Δγ between the actual speed ratio Rγ and the target speed ratio Tγ. Incidentally, the deviation Δγ is calculated by subtracting the target speed ratio Tγ from the actual speed ratio Rγ. Further, the feedback pressure Pinfb is increased when the deviation Δγ is a negative value, and is decreased when the deviation Δγ is a positive value. Thus, by increasing / decreasing the feedback pressure Pinfb, the deviation of the command pressure Pin from the appropriate value due to individual differences of the continuously variable transmission 4 or aging deterioration is eliminated, and the command pressure Pin acts on the primary pulley 18 based on the command pressure Pin. When the hydraulic pressure is adjusted, the actual speed ratio Rγ can be set to the target speed ratio Tγ.

  The deviation of the actual transmission ratio Rγ with respect to the target transmission ratio Tγ due to individual differences of the continuously variable transmission 4 or deterioration over time is steady, and when the steady deviation disappears through the increase or decrease of the feedback pressure Pinfb. The feedback pressure Pinfb converges to a value corresponding to the steady deviation.

Next, how to calculate the feedforward pressure Pinff used in the equation (2) will be described in detail.
This feedforward pressure Pinff is an actual speed change in accordance with a steady term Pinc, which is a hydraulic pressure to be applied to the primary pulley 18 in order to maintain the actual speed ratio Rγ at the target speed ratio Tγ, and a target speed ratio Tγ that changes during gear shifting. Based on the shift term Pins which is the hydraulic pressure to be applied to the primary pulley 18 in order to change the ratio Rγ, it is calculated using the following equation (3).

Pinff = Pinc + Pins (3)
Pinff: Feedback pressure
Pinc: stationary term
Pins: Transmission term The steady term Pinc of the equation (3) is the actual thrust RWout, which is the actual value of the thrust of the secondary pulley 19, and the pressure receiving area of the pulley 18 (movable sheave 18b) that receives the hydraulic pressure acting on the primary pulley 18. Based on Ain and the thrust ratio τ representing the ratio of the thrusts of the pulleys 18 and 19, the calculation is performed using the following equation (4).

Pinc = RWout / (τ · Ain) (4)
Pinc: stationary term
RWout: Feedback pressure
Ain: Pressure receiving area of primary pulley
τ: Thrust force ratio The actual thrust RWout is obtained by multiplying the actual oil pressure RPout, which is an actual value of the oil pressure acting on the secondary pulley 19, by the pressure receiving area Aout of the pulley 19. Further, the thrust ratio τ is calculated as a ratio (RWout / RWin) between the actual thrust RWout that is the actual value of the thrust of the secondary pulley 19 and the actual thrust RWin that is the actual value of the thrust of the primary pulley 18. Value. Specifically, the thrust ratio τ is based on the target speed ratio Tγ that is variably set as described above, and the safety factor SF that is a value representing a margin with respect to the necessary minimum value Woutmin of the actual thrust RWout of the secondary pulley 19. It is calculated with reference to a map predetermined by experiment or the like.

  The safety factor SF is calculated as “1”, “2”, “3”, “4”, “5” based on the ratio (RWout / Woutmin) between the actual thrust RWout and the necessary minimum value Woutmin. The larger the value is, the larger the margin is. The required minimum value Woutmin used for calculation of the safety factor SF is a value representing the minimum value of the actual thrust RWout required for suppressing the slip of the belt 20 with respect to the pulleys 18 and 19. The required minimum value Woutmin is the estimated input torque Tt obtained from the throttle opening, the winding radius Rin of the belt 20 with respect to the primary pulley 18, the friction coefficient μ between the belt 20 and the primary pulley 18, and the pinching of the primary pulley 18 Based on the angle α, it is calculated using the following equation (5).

Woutmin = Tt · cosα / (2 · μ · Rin) (5)
Woutmin: Minimum required value
Tt: Estimated input torque
α: Primary pulley clamping angle
μ: Friction coefficient
Rin: winding radius The winding radius Rin is a value representing the shortest distance from the center of rotation of the primary pulley 18 to the belt 20, and is calculated with reference to a map determined in advance by experiments or the like based on the actual gear ratio Rγ. Is done. Further, the sandwiching angle α of the primary pulley 18 is a value representing the inclination angle of the contact surface between the pulley 18 and the belt 20 with respect to a plane orthogonal to the center line of the pulley 18.

Further, the shift term Pins of the equation (3) is calculated using the following equation (6) based on the time change dgdt representing the change speed of the target gear ratio Tγ and the proportionality constant K.
Pins = dgdt / K (6)
Pins: Shift term
dgdt: Time change of the target gear ratio
K: Proportional constant The proportional constant K is a constant for obtaining the hydraulic pressure acting on the primary pulley 18 required to change the actual speed ratio Rγ in accordance with the changing target speed ratio Tγ from the time change dgdt. is there. The proportionality constant K is calculated with reference to a map set in advance through experiments or the like based on the actual speed ratio Rγ, the input rotational speed Nin, and the actual hydraulic pressure RPout acting on the secondary pulley 19.

Next, how to calculate the feedback pressure Pinfb used in the equation (2) will be described in detail.
The feedback pressure Pinfb is calculated using the following equation (7) based on the deviation Δγ between the actual speed ratio Rγ and the target speed ratio Tγ, the proportional gain Gp, and the integral gain Gi.

Pinfb = Δγ · Gp + ΣΔγ · Gi (7)
Pinb: Feedback pressure
Δγ: Deviation
Gp: Proportional gain
ΣΔγ: Deviation integrated value
Gi: integral gain The term “Δγ · Gp” on the right-hand side in equation (7) is a proportional term that takes a magnitude proportional to the deviation Δγ. This proportional term “Δγ · Gp” is used to increase / decrease the feedback pressure Pinfb by an amount corresponding to the deviation Δγ to increase / decrease the hydraulic pressure acting on the primary pulley 18 to bring the actual speed ratio Rγ closer to the target speed ratio Tγ. It is. Further, the proportional gain Gp used in the proportional term “Δγ · Gp” is a constant obtained in advance through experiments or the like.

  In addition, the term “ΣΔγ · Gi” on the right side of the equation (7) is a value between the actual speed ratio Rγ and the target speed ratio Tγ that cannot be canceled only by increasing / decreasing the feedback pressure Pinfb based on the proportional term “Δγ · Gp”. This is an integral term for eliminating the residual deviation. The integral term “Δγ · Gp” is used to increase or decrease the hydraulic pressure acting on the primary pulley 18 by an amount corresponding to the residual deviation so as to match the actual speed ratio Rγ and the target speed ratio Tγ. The deviation integrated value ΣΔγ used in the integral term “ΣΔγ · Gi” is a value obtained through integration processing in which the deviation Δγ is added at predetermined time intervals. In this integration process, a calculation “ΣΔγ ← previous ΣΔγ + Δγ” is executed at predetermined time intervals. Further, the integral gain Gi used in the integral term “ΣΔγ · Gi” is a constant obtained in advance through experiments or the like.

  The feedback pressure Pinfb calculated using the above equation (7) increases or decreases based on the deviation Δγ between the actual gear ratio Rγ and the target gear ratio Tγ so as to reduce the deviation Δγ. Through the increase / decrease of the feedback pressure Pinfb, feedback control for setting the actual speed ratio Rγ to the target speed ratio Tγ is performed. When the feedback control is performed, even if a steady shift of the actual speed ratio Rγ with respect to the target speed ratio Tγ occurs due to individual differences in the continuously variable transmission 4 or deterioration over time, the steady shift is described above. It can be eliminated by increasing or decreasing the feedback pressure Pinfb.

  Next, a description will be given of problems caused by adjustment of the hydraulic pressure acting on the primary pulley 18 for setting the actual transmission ratio Rγ of the continuously variable transmission 4 to the target transmission ratio Tγ, that is, the adjustment of the hydraulic pressure based on the command pressure Pin. To do.

  The indicated pressure Pin is calculated using the formula (2) based on the feedforward pressure Pinff and the feedback pressure Pinfb. By calculating the command pressure Pin in this way, the command pressure Pin is an appropriate value for setting the actual gear ratio Rγ of the continuously variable transmission 4 to the target gear ratio Tγ due to individual differences of the continuously variable transmission 4 or deterioration over time. It is suppressed that it deviates from.

  That is, when an influence such as individual difference of the continuously variable transmission 4 or aging deterioration appears as a deviation of the target speed ratio Tγ of the actual speed ratio Rγ, the deviation Δγ between the actual speed ratio Rγ and the target speed ratio Tγ is set to “0”. The feedback pressure Pinfb is increased or decreased. By such increase / decrease of the feedback pressure Pinfb, it is possible to eliminate the deviation of the indicated pressure Pin from the above-mentioned appropriate value due to individual differences of the continuously variable transmission 4 or aging deterioration, and as a result, the actual transmission gear ratio Rγ due to the deviation differs from the target gear ratio Tγ. The steady deviation is suppressed. Note that, as described above, the feedback pressure Pinfb when the steady shift of the actual speed ratio Rγ with respect to the target speed ratio Tγ disappears as described above converges to a value corresponding to the steady shift. .

  However, since the target transmission ratio Tγ of the continuously variable transmission 4 varies greatly depending on the driving state of the vehicle, etc., if the feedback pressure Pinfb is increased or decreased so that the actual transmission ratio Rγ becomes the above-described variable target transmission ratio Tγ, the feedback The pressure Pinfb also varies greatly. The feedback pressure Pinfb that fluctuates greatly as described above can be quickly converged to a value corresponding to a steady deviation of the actual speed ratio Rγ with respect to the target speed ratio Tγ due to individual differences of the continuously variable transmission 4 or deterioration over time. It is a difficult value, and it is inevitable that the convergence to a value corresponding to the steady deviation is delayed. Accordingly, the followability when the actual speed ratio Rγ of the continuously variable transmission 4 is made to follow the fluctuating target speed ratio Tγ by the amount that the convergence to the value corresponding to the steady deviation in the feedback pressure Pinfb occurs. Decreases.

Next, countermeasures of the present embodiment for suppressing the above-described problems will be described.
When the continuously variable transmission 4 is in steady operation, the feedback pressure Pinfb is stable, and when the feedback pressure Pinfb is away from “0” at that time, the actual speed change caused by individual differences of the continuously variable transmission 4, deterioration over time, or the like. This means that the steady deviation between the ratio Rγ and the target speed ratio Tγ is eliminated by the feedback pressure Pinfb. In this case, the feedback pressure Pinfb converges to a value corresponding to the steady deviation, and the feedback pressure Pinfb is used as a learning value G (i) that is a value corresponding to the steady deviation. Storage in a non-volatile memory is performed. After the learning value G (i) is stored in the nonvolatile memory in this way, the stored learning value G (i) is fed forward when the command pressure Pin is calculated using the equation (2). It is reflected in the pressure Pinff.

  As described above, when the learning value G (i) is stored, the learning value G (i) is subsequently reflected in the feedforward pressure Pinff, and the command pressure Pin is set to the steady state based on the feedforward pressure Pinff. It is calculated as a value that can eliminate the shift. Therefore, by adjusting the hydraulic pressure acting on the primary pulley 18 based on the command pressure Pin calculated in this way, the above-described problem occurs even if the target speed ratio Tγ varies greatly, that is, the target speed ratio Tγ. On the other hand, the occurrence of a problem that the followability when the actual speed ratio Rγ of the continuously variable transmission 4 is followed is suppressed. Accordingly, it is possible to improve the followability when the actual speed ratio Rγ of the continuously variable transmission 4 is made to follow the target speed ratio Tγ.

  FIG. 3 is a flowchart showing a learning value storage routine for storing the learning value G (i). This learning value storage routine is periodically executed through the transmission control computer 26, for example, with a time interruption every predetermined time.

  In this routine, first, it is determined whether or not the state in which the input rotation speed Nin is constant has continued long enough to be determined as steady operation (S101). If the determination is affirmative, the non-volatile memory uses the feedback pressure Pinfb as a learning value G (i) on condition that the absolute value of the feedback pressure Pinfb is equal to or greater than a predetermined determination value a (S102: YES). Is stored (S103). Here, the learning value G (i) is prepared for each of a plurality of learning regions i (i = 1 to 20) divided based on the target speed ratio Tγ and the safety factor SF as shown in FIG. In step 103, the feedback pressure Pinfb is stored as a learning value G (i) of the learning region i corresponding to the current target speed ratio Tγ ratio and safety factor SF. After the learning value G (i) is stored in this way, the feedback pressure Pinfb is set to “0” and initialized (S104).

  FIG. 5 is a flowchart showing a command pressure calculation routine for calculating the command pressure Pin by reflecting the stored learned value G (i) in the feedforward pressure Pinff. This command pressure calculation routine is periodically executed through the transmission control computer 26, for example, with a time interrupt at every predetermined time.

  In the routine, the learning value G (i) of the learning area i corresponding to the current target speed ratio Tγ and safety factor SF among the plurality of learning areas i is captured (S201). Thereafter, a process of reflecting the acquired learning value G (i) in the feedforward pressure Pinff is executed (S202). Then, based on the feedforward pressure Pinff reflecting the learning value G (i) and the feedback pressure Pinfb after initialization in step S104 of the learning value storage routine (FIG. 3), the command pressure is expressed using the equation (2). Pin is calculated (S203). Here, the reflection of the learned value G (i) in the feedforward pressure Pinff in the process of step 202 is realized by using, for example, any one of the following methods [1] to [3].

  [1] The learning value G (i) is added to the feedforward pressure Pinff calculated using the equation (3). In this case, the feedforward pressure Pinff after adding the learning value G (i) is used for calculating the command pressure Pin.

  [2] The learning value G (i) is added to the steady term Pinc calculated using the equation (4). In this case, by calculating the feedforward pressure Pinff based on the steady term Pinc after adding the learning value G (i), the feedforward pressure Pinff becomes a value reflecting the learning value G (i). The feedforward pressure Pinff is used for calculating the command pressure Pin.

  [3] The learning value G (i) is reflected in the thrust ratio τ used in the equation (4). Specifically, by multiplying the thrust ratio τ calculated based on the target speed ratio Tγ and the safety factor SF by the conversion coefficient H variably set based on the learning value G (i), The thrust ratio τ is a value that reflects the learning value G (i). In this case, the steady term Pinc is calculated based on the thrust ratio τ after being multiplied by the conversion coefficient H, and further the feedforward pressure Pinff is calculated based on the steady term Pinc, whereby the feedforward pressure Pinff becomes the learning value G. (i) is reflected, and the feedforward pressure Pinff is used to calculate the command pressure Pin.

  Next, the learning value G (i) is stored, and the movement of the feedforward pressure Pinff and the feedback pressure Pinfb when the learning value G (i) is reflected in the feedforward pressure Pinff is a time chart of FIG. Will be described with reference to FIG. In FIG. 6, (a) to (b) show changes in the input rotational speed Nin, the feedback pressure Pinfb, the feedforward pressure Pinff, and the gear ratio, respectively.

  In the example of FIG. 6, the feedback pressure Pinfb decreases during the period from the timing T1 to the timing T2, and based on this, the actual speed ratio Rγ changes toward the target speed ratio Tγ toward the increase side (low side). If the target speed ratio Tγ does not change during this process, the actual speed ratio Rγ reaches the target speed ratio Tγ (T2). Thereafter, when the state where the input rotational speed Nin is constant becomes long enough to be determined as steady operation (T3), if the absolute value of the feedback pressure Pinfb is equal to or greater than the determination value a, the feedback pressure Pinfb is the current target speed change. The learning value G (i) of the learning area i corresponding to the ratio Tγ and the safety factor SF is stored. When the learned value G (i) is stored as described above, the learned value G (i) is reflected in the feedforward pressure Pinff and the feedback pressure Pinfb is initialized to “0”. The pressure Pinfb and the feedforward pressure Pinff change as shown in FIGS. 6B and 6C, respectively.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When individual differences or aging deterioration of the continuously variable transmission 4 occurs, the steady deviation between the actual speed ratio Rγ and the target speed ratio Tγ can be eliminated by increasing or decreasing the feedback pressure Pinfb. Is possible. Accordingly, when the feedback pressure Pinfb is away from “0” during the steady operation of the continuously variable transmission 4, the steady deviation is eliminated by the feedback pressure Pinfb. In this case, the feedback pressure Pinfb has converged to a value corresponding to the steady deviation, and the feedback pressure Pinfb is stored as a learning value G (i) having a value corresponding to the steady deviation, and thereafter The learning value G (i) is reflected in the feedforward pressure Pinff. When the learned value G (i) is reflected in the feedforward pressure Pinff in this way, the command pressure Pin is calculated as a value that can eliminate the above-described steady deviation based on the feedforward pressure Pinff. By adjusting the hydraulic pressure acting on the primary pulley 18 based on the command pressure Pin, the followability when the actual speed ratio Rγ of the continuously variable transmission 4 is made to follow the target speed ratio Tγ that varies greatly is reduced. The occurrence of is suppressed. Accordingly, it is possible to improve the followability when the actual speed ratio Rγ of the continuously variable transmission 4 is made to follow the target speed ratio Tγ.

  (2) For example, the thrust ratio τ used in the equation (4), that is, the thrust ratio τ calculated with reference to the map deviates from the actual value due to the individual difference of the continuously variable transmission 4 or the aging deterioration. Appears in the form of Specifically, as an influence due to individual differences of the continuously variable transmission 4, aging deterioration, or the like, for example, the deviation of the actual value with respect to the calculated value of the estimated input torque Tt and the safety factor SF used for calculating the thrust ratio τ, and the linear solenoid valve 36 and the primary pulley control valve 35 cause a deviation from an appropriate value of the hydraulic pressure applied to the primary pulley 18. Then, they appear in the form of a deviation from the actual value of the calculated thrust ratio τ. In this case, the feedforward pressure Pinff calculated based on the thrust ratio τ becomes a value that is too large or too small with respect to the value required to realize the target speed ratio Tγ, and the instruction calculated based on the feedforward pressure Pinff The pressure Pin becomes a value deviated from an appropriate value for setting the actual speed ratio Rγ to the target speed ratio Tγ. As a result, the influence of individual differences of the continuously variable transmission 4 and aging deterioration, etc. is a steady state with respect to the target speed ratio Tγ of the actual speed ratio Rγ when the hydraulic pressure acting on the primary pulley 18 is adjusted based on the command pressure Pin. There is a risk of appearing as a gap. However, the learned value G (i) is stored as a value corresponding to such a steady deviation, and thereafter the learned value G (i) is always reflected in the feedforward pressure Pinff. Then, by calculating the command pressure Pin based on the feedforward pressure Pinff in which the learning value G (i) is reflected, the command pressure Pin is calculated as a value that can eliminate the steady deviation. Therefore, the same effect as the above (1) can be obtained even under a situation where the actual speed ratio Rγ is constantly deviated from the target speed ratio Tγ due to the above cause.

  (3) Since the influence of individual differences of the continuously variable transmission 4 and aging deterioration varies depending on the target speed ratio Tγ and the safety factor SF, a steady deviation of the actual speed ratio Rγ with respect to the target speed ratio Tγ due to the above-described influence. Varies depending on the target gear ratio Tγ and the safety factor SF. For this reason, a learning value G (i) is prepared for each of a plurality of learning regions i divided based on the target gear ratio Tγ and the safety factor SF, and the learning value G (i) is a value corresponding to the above-described steady deviation. Is stored for each learning area i. Then, the learning value G (i) of the learning region i corresponding to the current target speed ratio Tγ and the safety factor SF is reflected in the feedforward pressure Pinff, and the hydraulic pressure acting on the primary pulley 18 is adjusted based on the feedforward pressure Pinff. The command pressure Pin used for the calculation is calculated. For this reason, when the current target speed ratio Tγ and the safety factor SF are changed from a predetermined learning region i to another learning region i, the learning value G (i) reflected in the feedforward pressure Pinff is also adjusted accordingly. Is switched from one corresponding to the learning area i to one corresponding to the other learning area i. Therefore, even if the current target speed ratio Tγ and the safety factor SF change as described above, and the influence on the steady deviation due to individual differences of the continuously variable transmission 4 or aging deterioration changes, the feedforward By calculating the command pressure Pin based on the pressure Pinff, the command pressure Pin is calculated to be a value that can accurately eliminate the above-described steady deviation.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
This embodiment counts the number of learning regions G (i) stored in a plurality of learning regions i, and stops increasing or decreasing the feedback pressure Pinfb when the counted value is equal to or greater than a determination value. It is what you do. Accordingly, the engine control computer 25 for calculating the command pressure Pin can be obtained while improving the followability when the actual speed ratio Rγ of the continuously variable transmission 4 is made to follow the target speed ratio Tγ that varies greatly. It is possible to reduce the load of

FIG. 7 is a flowchart showing a learning value storage routine of the present embodiment.
In this routine, first, processing (S301 to S304) corresponding to steps S101 to S104 of the learning value storage routine (FIG. 3) of the first embodiment is executed. As this series of processing, it is determined whether or not the state in which the input rotational speed Nin is constant has continued long enough to determine that it is a steady operation (S301). And if it is affirmation determination here, on condition that the absolute value of the feedback pressure Pinfb is more than the predetermined determination value a (S302: YES), the feedback pressure Pinfb is the current target gear ratio Tγ ratio and The learning value G (i) of the learning area i corresponding to the safety factor SF is stored in the nonvolatile memory (S303). When the learning value G (i) is stored in this way, the feedback pressure Pinfb is set to “0” and initialized (S304).

  Thereafter, a process of counting the number of areas in which the learning value G (i) is stored among all the learning areas i is performed (S305), and the counted value is equal to or greater than a predetermined determination value b. (S306: YES), the increase / decrease of the feedback pressure Pinfb is stopped (S307). When the increase / decrease of the feedback pressure Pinfb is stopped in this way, the feedback pressure Pinfb is fixed to the value that was last increased / decreased.

  While the increase / decrease of the feedback pressure Pinfb is stopped, it is determined whether overshoot, undershoot, or hunting of the actual gear ratio Rγ with respect to the target gear ratio Tγ has occurred (S308).

  The above overshoot means that when the actual speed ratio Rγ is changed to the increase side (low side) and adjusted to the target speed ratio Tγ, the actual speed ratio Rγ becomes equal to the target speed ratio Tγ as shown by the solid line in FIG. It is a phenomenon that increases beyond. Then, the actual speed ratio Rγ and the target speed ratio Tγ are monitored, and the state where the actual speed ratio Rγ is larger than the target speed ratio Tγ by a predetermined value x1 or more continues for a predetermined time t1 or longer under the situation where the above phenomenon occurs. Based on the above, it is determined that the overshoot has occurred. It should be noted that the predetermined value x1 and the predetermined time t1 used here are determined in advance by experiments or the like as values that can accurately determine that the overshoot has occurred.

  The undershoot means that when the actual speed ratio Rγ is changed to the decreasing side (high side) and adjusted to the target speed ratio Tγ, the actual speed ratio Rγ becomes equal to the target speed ratio Tγ as shown by the solid line in FIG. It is a phenomenon that decreases beyond that. Then, the actual speed ratio Rγ and the target speed ratio Tγ are monitored, and the state where the actual speed ratio Rγ is greater than the target speed ratio Tγ by a predetermined value x2 or more continues for a predetermined time t2 or longer under the situation where the above phenomenon occurs. Based on the above, it is determined that the undershoot has occurred. Note that the predetermined value x2 and the predetermined time t2 used here are determined in advance by experiments or the like as values that can accurately determine that the undershoot has occurred.

  The hunting means that when the actual speed ratio Rγ is made to reach the target speed ratio Tγ, the actual speed ratio Rγ is increased with respect to the target speed ratio Tγ as shown by the broken line in FIG. 8 and the broken line in FIG. This is a phenomenon in which reversal is repeated between the low side and the decreasing side (high side). Then, the actual speed ratio Rγ and the target speed ratio Tγ are monitored, and when the number of occurrences of the reversal within a predetermined time becomes equal to or greater than the predetermined value x3 under the situation where the phenomenon occurs, the hunting is performed. It is determined that it has occurred. The predetermined value x3 used here is determined in advance by experiments or the like as a value with which it is possible to accurately determine that the hunting has occurred.

  As described above, it is determined whether overshoot, undershoot, or hunting of the actual speed ratio Rγ with respect to the target speed ratio Tγ has occurred. If at least one of the overshoot, undershoot, and hunting occurs while the increase / decrease of the feedback pressure Pinfb is stopped, an affirmative determination is made in step S308. In this case, the value counted in step S305 is reset to “0” (S309), the increase / decrease stop of the feedback pressure Pinfb is released, and the increase / decrease is resumed (S310).

According to the embodiment described in detail above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(4) If the learning value G (i) is stored in a certain number of learning regions i among all of the plurality of learning regions i, the actual speed ratio Rγ of the continuously variable transmission 4 is set to the target speed ratio Tγ. The effect of the above (1) that the followability at the time of following can be improved can be obtained. Therefore, by appropriately setting the determination value b used in step S306 (FIG. 7) of the learning value learning routine, when the effect of the above (1) can be obtained, the increase / decrease in the feedback pressure Pinfb is stopped, The load on the transmission control computer 26 when calculating the command pressure Pin can be reduced.

  (5) While the increase / decrease of the feedback pressure Pinfb is stopped, the aging deterioration of the continuously variable transmission 4 progresses and the influence of the same aging deterioration becomes large. When the shift changes (in this example, increases), the stored learning value G (i) becomes an inappropriate value as a value corresponding to the steady shift. In this case, even if the command pressure Pin is calculated based on the feedforward pressure Pinff reflecting the learning value G (i), the command pressure Pin does not become a value that can eliminate the steady deviation. . For this reason, when adjusting the hydraulic pressure acting on the primary pulley 18 based on the command pressure Pin to set the actual gear ratio Rγ to the target gear ratio Tγ, an overshoot, an undershoot of the actual gear ratio Rγ with respect to the target gear ratio Tγ, or Hunting may occur. When it is determined that such overshoot, undershoot, or hunting has occurred while the increase / decrease of the feedback pressure Pinfb is stopped, the increase / decrease of the feedback pressure Pinfb is resumed, and the learning value G (i) in each learning region i is resumed. The memory will be redone. Therefore, even when the steady shift of the actual speed ratio Rγ of the continuously variable transmission 4 with respect to the target speed ratio Tγ changes while the feedback pressure Pinfb is stopped increasing or decreasing, the learning value G (i) is changed to the value after the change. An appropriate value can be stored as a value corresponding to the steady deviation.

[Other Embodiments]
In addition, each said embodiment can also be changed as follows, for example.
In the second embodiment, when the overshoot, undershoot, or hunting of the actual speed ratio Rγ with respect to the target speed ratio Tγ occurs while the increase / decrease of the feedback pressure Pinfb is stopped, the feedback pressure Pinfb is changed only in the learning region i in which they occur. The increase / decrease stop may be canceled to restart the increase / decrease, and the learning value G (i) of the learning region i may be stored again.

  In the first and second embodiments, the number of learning areas i may be changed as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Crankshaft, 2 ... Torque converter, 3 ... Forward / reverse switching device, 4 ... Continuously variable transmission, 4a ... Input shaft, 4b ... Output shaft, 5 ... Intake passage, 6 ... Throttle valve, 7 ... Accelerator pedal, 8 ... pump impeller, 9 ... turbine shaft, 10 ... turbine impeller, 11 ... oil pump, 12 ... throttle position sensor, 13 ... fuel injection valve, 16 ... hydraulic sensor, 18 ... primary pulley, 18a ... fixed Sheave, 18b ... movable sheave, 19 ... secondary pulley, 19a ... fixed sheave, 19b ... movable sheave, 20 ... belt, 21 ... hydraulic control circuit, 25 ... engine control computer, 26 ... transmission control computer (calculation means, learning means, (Reflecting means, stopping means), 27 ... accelerator position sensor, 28 ... shift Bar 31, oil passage 32, primary regulator valve 33 33 secondary pulley control valve 34 linear actuator valve 35 primary pulley control valve 36 linear solenoid valve 29 input rotation speed sensor 30 output rotation Speed sensor.

Claims (5)

Applicable to a continuously variable transmission in which the gear ratio is adjusted by changing the distance from the rotation center of the pulley to the belt by driving one of the primary and secondary pulleys around which the belt is wound by hydraulic pressure. A control device for a continuously variable transmission that calculates a command pressure of the hydraulic pressure for setting an actual gear ratio of the continuously variable transmission as a target gear ratio and adjusts a hydraulic pressure acting on the pulley based on the command pressure; ,
Based on the feedforward pressure calculated as the hydraulic pressure required for realizing the target speed ratio, and the deviation between the actual speed ratio and the target speed ratio, the indicated pressure is made close to “0”. Calculating means for calculating based on the feedback pressure that increases and decreases so
When the state where the input rotational speed of the continuously variable transmission is constant continues for a long time that can be determined as steady operation, the feedback pressure is set on condition that the absolute value of the feedback pressure is equal to or greater than a predetermined determination value. Learning means for storing as a learning value;
Reflecting means for reflecting the stored learning value in the feedforward pressure when the calculated pressure is calculated by the calculating means;
A control device for a continuously variable transmission. Of the primary pulley and the secondary pulley, the secondary pulley sandwiches the belt so as not to slip due to thrust generated through the action of hydraulic pressure, and the primary pulley is generated through the action of hydraulic pressure adjusted based on the indicated pressure. It is driven by thrust to change the distance from the rotation center of the pulley to the belt,
The feedforward pressure is a ratio between the thrust of the secondary pulley and the thrust of the primary pulley, and is a value representing the ratio when the actual speed ratio can be maintained at the target speed ratio during steady operation. Calculated based on
2. The thrust ratio is calculated based on a safety factor representing a margin with respect to a minimum necessary value for preventing slippage of the belt in an actual thrust of the secondary pulley, and the target speed ratio. The control device of the continuously variable transmission described. The learning value is prepared for each of a plurality of learning areas partitioned based on the target gear ratio and the safety factor,
The learning means is provided that the absolute value of the feedback pressure is equal to or greater than a predetermined determination value when the state where the input rotational speed of the continuously variable transmission is long enough to be determined as steady operation. And storing the feedback pressure as a learning value in a learning region corresponding to the current target speed ratio and safety factor,
3. The continuously variable means according to claim 2, wherein when the command pressure is calculated by the calculation means, the reflection means reflects a learning value of a learning region corresponding to a current target gear ratio and a safety factor in the feedforward pressure. Transmission control device. The control device for a continuously variable transmission according to claim 3,
The system further comprises a stopping unit that counts the number of areas in which the learning values are stored among the plurality of learning areas, and stops increasing or decreasing the feedback pressure when the counted value is equal to or greater than a determination value. A control device for a continuously variable transmission. The stop means is in a state where the increase / decrease of the feedback pressure is stopped, and when the hydraulic pressure acting on the primary pulley is adjusted based on the command pressure to set the actual gear ratio to the target gear ratio, When it is determined that an actual gear ratio overshoot, undershoot, or hunting has occurred, the counted value is reset to the initial value “0” and the increase / decrease of the feedback pressure is released and the increase / decrease is stopped. The control device for the continuously variable transmission according to claim 4, wherein the control is resumed.

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