JP2023182397A - Control device of continuously variable transmission for vehicle - Google Patents

Abstract

To prevent the ratio (speed ratio) of a continuously variable transmission from being excessively shifted to a low side (low speed side) when a problem such as a failure occurs in a rotation speed sensor of the continuously variable transmission.SOLUTION: A control device of a continuously variable transmission for a vehicle comprises a hydraulic pressure supply device (46) for supplying hydraulic pressure applied to a drive pulley (26a) of the continuously variable transmission (26), and the control device (90) for controlling the supply of hydraulic pressure by the hydraulic pressure supply device (46). The control device for the continuously variable transmission for the vehicle performs feedback control of hydraulic pressure so that the actual speed ratio of the continuously variable transmission (26) calculated based on the detected value of a rotation speed sensor (72) becomes a target speed ratio, and when the actual speed ratio is equal to or less than a predetermined speed ratio, performs speed ratio feedback gain reduction control for setting a feedback gain value of the speed ratio in the feedback control to a smaller value than that when the actual speed ratio is greater than the predetermined speed ratio.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for a continuously variable transmission for a vehicle, which is constructed by winding a power transmission member such as a metal chain or belt between a drive pulley and a driven pulley.

The vehicle is configured to transmit the output from the drive wheels to the drive wheels by changing the speed using a transmission. As a transmission, for example, as shown in Patent Document 1, a continuously variable transmission having a belt mechanism configured by winding an endless belt around a driving pulley and a driven pulley with variable pulley width is well known. ing. This transmission changes the speed steplessly by changing the pulley width by controlling the hydraulic pressure of the hydraulic oil supplied to the driving pulley and the driven pulley, and by changing the radius of the belt around the pulley. The ratio can be changed and controlled. A vehicle having such a transmission is provided with a control device for controlling oil pressure according to the vehicle state and controlling the operation of the transmission.

Japanese Patent Application Publication No. 2022-45709

The continuously variable transmission control device configured as described above controls the hydraulic pressure supplied to the continuously variable transmission based on the detected value of the rotation speed sensor that detects the rotation speed of the drive side pulley and the driven side pulley of the continuously variable transmission. It is supposed to be done. However, in the unlikely event that the rotation speed sensor is unable to output a normal detection value due to a malfunction or other malfunction, it may interfere with the speed change control of the continuously variable transmission. There is a need to.

Conventionally, as a method for determining the failure of the rotation speed sensor of a continuously variable transmission, for example, the rotation speed of the turbine of the torque converter installed on the input side of the continuously variable transmission and the rotation of the gear installed on the output side have been used. The difference between the rotation speed of the element and the rotation speed is detected, and if the value of the difference is not a normal value, it is determined that the rotation speed sensor is malfunctioning. However, with this method, it takes a certain amount of time to determine that the rotation speed sensor is faulty. This may result in temporary inappropriate control, such as the transmission gear ratio becoming an excessively low ratio.

In addition, as another method for determining the failure of the rotation speed sensor of a continuously variable transmission, detection values of other rotation speed sensors that detect the rotation speed of rotating elements such as gears and shafts other than the continuously variable transmission are used. It is conceivable to control the speed change of a continuously variable transmission using a continuously variable transmission, but in that case, if a clutch is interposed between the continuously variable transmission and other rotating elements, the engagement state of the clutch may be unknown. In this case, there is a possibility that this method cannot be used because it is not certain that the detected values of other rotational speed sensors accurately reflect the current rotational speed of the continuously variable transmission.

Furthermore, in case the rotation speed sensor fails, it may be possible to install another rotation speed sensor in a separate system, but doing so may increase the cost and weight of the vehicle due to the addition of the rotation speed sensor. be.

The present invention has been made to solve the above problems, and its purpose is to provide a relatively simple configuration and control, and to prevent problems such as failure of the rotation speed sensor of the continuously variable transmission. An object of the present invention is to provide a control device for a continuously variable transmission that can maintain appropriate control of the gear ratio of the continuously variable transmission even in the case of a continuous variable transmission.

In order to solve the above problems, a control device for a continuously variable transmission for a vehicle according to the present invention includes a drive pulley (26a) that rotates when the driving force from a drive source (10) of the vehicle is transmitted, and a control device for a continuously variable transmission for a vehicle according to the present invention. A driven pulley (26b) that transmits driving force to the output side, and a power transmission member (26c) wound between the drive pulley (26a) and the driven pulley (26b), the drive pulley By changing the pulley widths of the driven pulley (26a) and the driven pulley (26b), a continuously variable transmission (26 ), a rotation speed sensor (72) that detects the rotation speed of the drive pulley (26a) or the driven pulley (26b), and a hydraulic pressure supply device (46) that supplies hydraulic pressure applied to the drive pulley (26a). A control device for a continuously variable transmission for a vehicle, comprising: a control device (90) that controls the supply of hydraulic pressure by the hydraulic pressure supply device (46), wherein the control device (90) is configured to control the rotation speed sensor (72). ) Feedback control of the hydraulic pressure is performed so that the actual gear ratio of the continuously variable transmission (26) calculated based on the detected value of the continuously variable transmission (26) becomes the target gear ratio, and when the actual gear ratio is less than or equal to the predetermined gear ratio. The present invention is characterized in that a gear ratio feedback gain reduction control is performed in which a feedback gain value of the gear ratio in the feedback control is set to a smaller value than when the actual gear ratio is larger than the predetermined gear ratio.

In a control device for a continuously variable transmission for a vehicle, if the actual gear ratio is below a predetermined gear ratio, there is a malfunction such as a failure in the rotation speed sensor that detects the rotation speed of the drive pulley or driven pulley of the continuously variable transmission. According to the present invention, in such a case, the value of the feedback gain of the gear ratio in feedback control is set to a smaller value than when the actual gear ratio is larger than the predetermined gear ratio. By performing the gear ratio feedback gain reduction control, it is possible to prevent the ratio (gear ratio) of the continuously variable transmission from being excessively shifted to a low side (low speed side) ratio.

Further, according to the control device for a continuously variable transmission for a vehicle according to the present invention, problems such as failure of the rotation speed sensor can be prevented without increasing the number of rotation speed sensors installed or performing complicated control. It is possible to prevent the ratio (speed ratio) of the continuously variable transmission from being shifted excessively to the low side (low speed side) by appropriately determining whether the 1. Even if an abnormality such as a failure occurs in the rotation speed sensor, it is possible to ensure the stability of the vehicle's behavior until the vehicle is stopped in a safe location.

Further, in this control device for a continuously variable transmission for a vehicle, the predetermined gear ratio may be the smallest gear ratio that the continuously variable transmission (26) can take structurally, or a smaller gear ratio than that. Note that the smallest gear ratio that the continuously variable transmission can take structurally here may be, as an example, the gear ratio at the OD end of the continuously variable transmission (CVT) in the embodiment described later.

According to this configuration, the predetermined gear ratio is the smallest gear ratio that the continuously variable transmission can take due to its structure, and if the actual gear ratio is less than or equal to this predetermined gear ratio, the rotation speed sensor may malfunction. There is a high possibility that a problem has occurred. Therefore, it is possible to appropriately determine that a problem such as a failure has occurred in the rotation speed sensor and perform gear ratio feedback gain reduction control, so that the behavior of the vehicle can be controlled until the vehicle is stopped in a safe place. It becomes possible to ensure stability.

Further, in this control device for a continuously variable transmission for a vehicle, the control device (90) has a target speed change map for obtaining the target speed change ratio, and the target speed change ratio on the target speed change map is used for control purposes. The gear ratio feedback gain reduction control may be performed when the gear ratio is within a range of gear ratios that are not used and is larger than the smallest gear ratio that the continuously variable transmission (26) can take structurally. good.

According to this configuration, when the target gear ratio on the target gear change map is within the range of gear ratios that are not used for control and is smaller than the smallest gear ratio that the continuously variable transmission can take structurally, In this case, there is a high possibility that the rotation speed sensor is malfunctioning or has malfunctioned. Therefore, it is possible to appropriately determine that a problem such as a failure has occurred in the rotation speed sensor and perform gear ratio feedback gain reduction control, so that the behavior of the vehicle can be controlled until the vehicle is stopped in a safe place. It becomes possible to ensure stability.

Further, in this control device for a continuously variable transmission for a vehicle, a vehicle speed detection means (76) for detecting the vehicle speed (V) of the vehicle, an accelerator operator (56) operated by the driver of the vehicle, and the an accelerator opening detection means (56a) for detecting an accelerator opening (AP) due to the operation of an accelerator operator (56); , may be set based on the accelerator opening (AP) and the vehicle speed (V).

Furthermore, the range of gear ratios (S1, S2) that are not used for control in the target gear change map may be a range that is equal to or lower than the gear ratio when the accelerator opening (AP) is substantially in the fully closed state.

Further, this control device for a continuously variable transmission for a vehicle includes a torque converter (24) equipped with a lock-up clutch (24c) mounted on the vehicle, and the lock-up clutch (24c) is off, the gear ratio area (S1) that is not used for control in the target gear shift map is the accelerator opening degree (AP) and the vehicle speed (V) when the lock-up clutch (24c) is on. The target speed change map may be set to a value on the target shift map based on the target speed change map.

When the vehicle speed is lower than a predetermined vehicle speed, the lock-up clutch of the torque converter installed in the vehicle is turned off, which causes the drive pulley rotation speed, which is the input rotation speed of the continuously variable transmission, to decrease. A temporary change in rotational speed (gear ratio) may occur. Therefore, when the vehicle speed is below a predetermined speed and the lock-up clutch is off, a gear ratio area that is not used for control is set in the target shift map based on the accelerator opening and vehicle speed with the lock-up clutch on. By doing so, it is possible to detect problems such as malfunctions in the rotation speed sensor without being affected by temporary changes in the rotation speed of the drive pulley caused by the lock-up clutch of the torque converter turning off. Able to make appropriate judgments.

The control device for a continuously variable transmission for a vehicle also includes a low friction coefficient road determining means for determining whether or not the road surface on which the vehicle is traveling is on a low friction coefficient road where the friction coefficient of the road surface is equal to or less than a predetermined value. , the control device (90) does not perform the gear ratio feedback gain reduction control when the low friction coefficient road determining means determines that the road surface on which the vehicle is traveling is a low friction coefficient road. You can do it like this.

When the road surface on which the vehicle is running has a low coefficient of friction, sudden changes in wheel speed or vehicle speed or their accelerations may occur due to wheel slip, etc., and due to this, the rotation There is a possibility that a temporary change in the rotation speed (speed ratio) of the continuously variable transmission detected by several sensors may occur. Therefore, if the road surface on which the vehicle is running is a low friction coefficient road, by not performing gear ratio feedback gain reduction control, it is possible to prevent the vehicle from running on a low friction coefficient road. It is possible to appropriately determine whether a problem such as a failure has occurred in the rotation speed sensor without being affected by a temporary change in the rotation speed of the continuously variable transmission caused by the rotation speed sensor.
Note that the above reference numerals in parentheses indicate the reference numerals of constituent elements in the embodiments to be described later, as examples of the present invention.

According to the control device for a continuously variable transmission for a vehicle according to the present invention, the configuration and control are relatively simple, and even if a malfunction such as a failure occurs in the rotation speed sensor of the continuously variable transmission, Appropriate control of the gear ratio of the transmission can be maintained.

1 is a schematic diagram showing an example of the overall configuration of a vehicle equipped with a control device for a continuously variable transmission for a vehicle according to an embodiment of the present invention. It is a hydraulic circuit diagram of a hydraulic pressure supply mechanism. FIG. 2 is a block diagram showing a shift control system of a CVT (continuously variable transmission). 5 is a timing chart showing changes over time in each value when speed ratio feedback gain reduction control is not implemented and when it is implemented. It is a figure which shows the target gear change map for obtaining the target value of a gear ratio.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an example of the overall configuration of a vehicle equipped with a control device for a continuously variable transmission for vehicles according to an embodiment of the present invention. The vehicle shown in the figure includes an engine (internal combustion engine) 10 as a drive source, a torque converter 24 with a lock-up clutch 24c, and a transmission mechanism (continuously variable transmission mechanism) that changes the speed and outputs rotation by the driving force of the engine 10. ) 26 and a forward/reverse switching device 28. The forward/reverse switching device 28 includes a forward clutch 28a provided to connect/disconnect transmission of the driving force of the engine 10 to the transmission mechanism 26. The vehicle also includes an engine controller 66 and a shift controller 90, which are control devices for controlling the engine 10, transmission mechanism 26, and forward/reverse switching device 28 described above.

A throttle valve (not shown) disposed in the intake system of the engine 10 is connected to an actuator such as an electric motor that is mechanically disconnected from an accelerator pedal (accelerator operator) 56 disposed in the driver's seat of the vehicle. It is connected to a DBW (Drive By Wire) mechanism 16, and is opened and closed by the DBW mechanism 16.

The intake air metered by the throttle valve flows through an intake manifold (not shown), mixes with the fuel injected from the injector 20 near the intake port of each cylinder to form a mixture, and then passes through the intake valve (not shown). When the valve (not shown) is opened, it flows into the combustion chamber (not shown) of the cylinder concerned. The air-fuel mixture is ignited and burned in the combustion chamber, driving the piston and rotating the crankshaft 22, and then being discharged to the outside of the engine 10 as exhaust gas.

The crankshaft 22 of the engine 10 is connected to a pump impeller 24a of a torque converter 24, while a turbine runner 24b disposed opposite thereto and receiving fluid (hydraulic oil) is connected to a main shaft (input shaft) MS. Ru. As a result, the rotation of the crankshaft 22 is input to the transmission mechanism 26 via the torque converter 24. The transmission mechanism 26 includes a continuously variable transmission (hereinafter referred to as "CVT") 26.

The CVT 26 includes a main shaft MS, more precisely a drive pulley 26a arranged on the outer shaft thereof, and a counter shaft (output shaft) CS parallel to the main shaft MS, more precisely a driven pulley arranged on the outer shaft thereof. It consists of a pulley 26b and an endless flexible member, for example, a metal belt 26c, which is stretched around the pulley 26b.

The drive pulley 26a includes a fixed pulley half 26a1, which is disposed on the outer shaft of the main shaft MS so that it cannot rotate relative to it and cannot move in the axial direction, and a fixed pulley half 26a1 that cannot rotate relative to the outer shaft of the main shaft MS. It consists of a movable pulley half body 26a2 that is relatively movable in the axial direction. The driven pulley 26b includes a fixed pulley half 26b1 that cannot rotate relative to the outer peripheral shaft of the counter shaft CS and cannot move in the axial direction, and a fixed pulley half 26b1 that cannot rotate relative to the counter shaft CS and is arranged axially with respect to the fixed pulley half 26b1. It consists of a movable pulley half body 26b2 that is relatively movable.

CVT 26 is connected to engine 10 via forward/reverse switching device 28 . The forward/reverse switching device 28 includes a forward clutch (disconnecting device) 28a that allows the vehicle to travel in the forward direction, a reverse brake clutch 28b that allows the vehicle to travel in the reverse direction, and a planetary gear mechanism disposed between them. It consists of 28c. CVT 26 is connected to engine 10 via forward clutch 28a.

In the planetary gear mechanism 28c, the sun gear 28c1 is fixed to the main shaft MS, and the ring gear 28c2 is fixed to the fixed pulley half 26a1 of the drive pulley 26a via the forward clutch 28a. A pinion 28c3 is arranged between the sun gear 28c1 and the ring gear 28c2. Pinion 28c3 is connected to sun gear 28c1 by carrier 28c4. The carrier 28c4 is fixed (locked) when the reverse brake clutch 28b is operated.

The rotation of the countershaft CS is transmitted from the secondary shaft (intermediate shaft) SS to the drive wheels 12 via gears. That is, the rotation of the countershaft CS is transmitted to the secondary shaft SS via the gears 30a and 30b, and the rotation is transmitted from the differential 32 to the left and right drive wheels (only the right side is shown) 12 via the gear 30c.

In the forward/reverse switching device 28, the forward clutch 28a and the reverse brake clutch 28b are switched by the driver operating a range selector 44 provided at the driver's seat of the vehicle to select one of the ranges, such as P, R, N, or D. This is done through selection. Range selection by the driver's operation of the range selector 44 is transmitted to a manual valve of a hydraulic pressure supply mechanism 46 (described later).

For example, when the D, S, or L range is selected via the range selector 44, the spool of the manual valve moves accordingly, and hydraulic oil (hydraulic pressure) is discharged from the piston chamber of the reverse brake clutch 28b. Hydraulic pressure is supplied to the piston chamber of the forward clutch 28a, and the forward clutch 28a is engaged.

When the forward clutch 28a is engaged, all the gears rotate together with the main shaft MS, and the drive pulley 26a is driven in the same direction (forward direction) as the main shaft MS, so that the vehicle travels in the forward direction.

When the R range is selected, hydraulic oil is discharged from the piston chamber of the forward clutch 28a, while hydraulic pressure is supplied to the piston chamber of the reverse brake clutch 28b, thereby operating the reverse brake clutch 28b. Therefore, carrier 28c4 is fixed, ring gear 28c2 is driven in the opposite direction to sun gear 28c1, drive pulley 26a is driven in the opposite direction (reverse direction) to main shaft MS, and the vehicle runs in the reverse direction.

When the P or N range is selected, hydraulic oil is discharged from both piston chambers, the forward clutch 28a and the reverse brake clutch 28b are both released, power transmission via the forward/reverse switching device 28 is cut off, and the engine 10 and the drive pulley 26a of the CVT 26 is cut off.

FIG. 2 is a hydraulic circuit diagram of the hydraulic pressure supply mechanism 46. As shown in the figure, the hydraulic supply mechanism 46 is provided with a hydraulic pump 46a. The hydraulic pump 46a is a gear pump and is driven by the engine 10 to pump up the hydraulic oil stored in the reservoir 46b and forcefully send it to the PH control valve 46c. On the other hand, the output of the PH control valve 46c (PH pressure (line pressure)) is transmitted from the oil passage 46d to the piston chamber of the movable pulley half 26a2 of the drive pulley 26a of the CVT 26 via the first and second regulator valves 46e and 46f. (DR) 26a21 and the piston chamber (DN) 26b21 of the movable pulley half 26b2 of the driven pulley 26b, and on the other hand, it is connected to the CR valve 46h via the oil passage 46g.

The CR valve 46h reduces the PH pressure to generate CR pressure (control pressure), and supplies it to the first, second, and third (electromagnetic) linear solenoid valves 46j, 46k, and 46l from the oil passage 46i. The first and second linear solenoid valves 46j and 46k act on the first and second regulator valves 46e and 46f with an output pressure determined according to the excitation of the solenoid, and therefore the PH sent from the oil path 46d Pressure hydraulic oil is supplied to the piston chambers 26a21, 26b21 of the movable pulley halves 26a2, 26b2, and pulley side pressure is generated accordingly.

Therefore, pulley side pressure that moves the movable pulley halves 26a2, 26b2 in the axial direction is generated, the pulley widths of the drive pulley 26a and the driven pulley 26b change, and the wrapping radius of the belt 26c changes. In this way, by adjusting the side pressure of the pulley, the ratio (speed ratio) for transmitting the output of the engine 10 to the drive wheels 12 can be changed steplessly.

The output (CR pressure) of the CR valve 46h is also connected to the CR shift valve 46n via an oil path 46m, and from there to the piston chamber (FWD) 28a1 of the forward clutch 28a of the forward/reverse switching device 28 via the manual valve 46o. and a piston chamber (RVS) 28b1 of the reverse brake clutch 28b.

As described above, the manual valve 46o transfers the output of the CR shift valve 46n to the piston chambers 28a1 and 28b1 of the forward clutch 28a and the reverse brake clutch 28b according to the position of the range selector 44 operated (selected) by the driver. Connect to either.

Further, the output of the PH control valve 46c is sent to the TC regulator valve 46q via the oil path 46p, and the output of the TC regulator valve 46q is connected to the LC shift valve 46s via the LC control valve 46r.

The output of the LC shift valve 46s is connected to the piston chamber 24c1 of the lock-up clutch 24c of the torque converter 24 on the one hand, and to the chamber 24c2 on the rear side thereof on the other hand.

While hydraulic oil is supplied to the piston chamber 24c1 via the LC shift valve 46s, when it is discharged from the rear chamber 24c2, the lock-up clutch 24c is engaged (turned on) and the hydraulic oil is supplied to the rear chamber 24c2. On the other hand, when the piston is discharged from the piston chamber 24c1, it is released (turned off). The amount of slip of the lock-up clutch 24c is determined by the amount of hydraulic oil supplied to the piston chamber 24c1 and the rear chamber 24c2.

The output of the CR valve 46h is connected to an LC control valve 46r and an LC shift valve 46s via an oil passage 46t, and a fourth linear solenoid valve 46u is inserted into the oil passage 46t. The slip amount of the lock-up clutch 24c is adjusted (controlled) by energizing/de-energizing the solenoid of the fourth linear solenoid valve 46u.

Returning to the explanation of FIG. 1, an engine rotation speed sensor (crank angle sensor) 50 is provided at an appropriate position such as near a camshaft (not shown) of the engine 10. The engine rotation speed sensor 50 outputs a signal indicating the engine rotation speed NE at each predetermined crank angle position of the piston.

The actuator of the DBW mechanism 16 is provided with a throttle opening sensor 54 . The throttle opening sensor 54 outputs a signal proportional to the throttle valve opening TH through the rotation amount of the actuator. Further, an accelerator opening sensor 56a is provided near the accelerator pedal 56. The accelerator opening sensor 56a outputs a signal proportional to the accelerator opening AP, which corresponds to the amount of operation of the accelerator pedal by the driver.

Outputs from the engine rotation speed sensor 50 and the like are sent to an engine controller (control means) 66. The engine controller 66 includes a microcomputer, determines the target throttle opening based on the sensor outputs, controls the operation of the DBW mechanism 16, determines the fuel injection amount, and drives the injector 20. Further, the engine controller 66 controls the engine rotation speed (idle rotation speed).

An NT sensor (rotation speed sensor) 70 is provided on the main shaft MS. The NT sensor 70 generates a pulse indicating the rotation speed of the turbine runner 24b, specifically the rotation speed NT of the main shaft MS (transmission input shaft rotation speed), and more specifically, the input shaft rotation speed of the forward clutch 28a. Output a signal.

An NDR sensor (rotation speed sensor) 72 is provided near the drive pulley 26a of the CVT 26. The NDR sensor 72 outputs a pulse signal according to the rotation speed NDR of the drive pulley 26a, in other words, the output shaft rotation speed of the forward clutch 28a.

An NDN sensor (rotation speed sensor) 74 is provided near the driven pulley 26b. The NDN sensor 74 outputs a pulse signal indicating the rotation speed NDN of the driven pulley 26b, that is, the rotation speed of the counter shaft CS (transmission output shaft rotation speed). A vehicle speed sensor (rotation speed sensor) 76 is provided near the gear 30b of the secondary shaft SS. Vehicle speed sensor 76 outputs a pulse signal indicating vehicle speed V through the rotation speed of secondary shaft SS.

A range selector switch 44a is provided near the range selector 44. The range selector switch 44a outputs a signal corresponding to a range such as R, N, or D selected by the driver.

As shown in FIG. 2, an oil pressure sensor 82 is arranged in an oil path in the oil pressure supply mechanism 46 that leads to the driven pulley 26b of the CVT 26. The oil pressure sensor 82 outputs a signal corresponding to the oil pressure supplied to the piston chamber 26b21 of the movable pulley half 26b2 of the driven pulley 26b. Further, an oil temperature sensor 84 is arranged in the reservoir 46b. The oil temperature sensor 84 outputs a signal according to the oil temperature (temperature TATF of the hydraulic oil ATF). The oil pressure sensor 82 is arranged in the oil passage between the piston chamber 28a1 of the forward clutch 28a and the manual valve 46o, or in the oil passage leading to the lock-up clutch 24c of the torque converter 24, as shown by the imaginary line in FIG. The oil pressure at that location may also be detected.

The outputs of the NT sensor 70 and the like, including the outputs of other sensors (not shown), are sent to a shift controller (control means) 90 shown in FIG. 1. The shift controller 90 also includes a microcomputer and is configured to freely communicate with the engine controller 66. Based on these detected values, the shift controller 90 energizes and de-energizes electromagnetic solenoids such as the first and fourth on/off solenoids 46u of the hydraulic pressure supply mechanism 46 to control the forward/reverse switching device 28, CVT 26, and torque converter 24. Control behavior.

Next, the shift control system of the CVT 26 will be explained. FIG. 3 is a block diagram showing a CVT shift control system. As shown in the figure, the shift controller 90 that controls the gear ratio of the CVT 26 includes a target gear ratio determining section M1, a gear ratio feedback PID control section M2, and a gear ratio feedback gain reduction control execution determining section M3.

The target gear ratio determining unit M1 determines the rotation speed of the drive pulley 26a detected by the NDR sensor 72 (DR pulley rotation speed), the rotation speed of the driven pulley 26b detected by the NDN sensor 74 (DN pulley rotation speed), the vehicle speed, A target gear ratio of the CVT 26 is calculated based on the accelerator pedal opening degree and the like. The subtractor 91 subtracts the actual speed ratio calculated based on the rotation speed of the drive pulley 26a and the rotation speed of the driven pulley 26b from the target speed ratio calculated by the target speed ratio determination unit M1, thereby determining the deviation of the speed change ratio. Calculate. The gear ratio feedback PID control unit M2 performs PID processing on the gear ratio deviation input from the subtractor 91, and calculates a PID feedback control amount for converging the deviation to zero. At this time, when the gear ratio feedback gain reduction control execution determination unit M3 determines that the gear ratio feedback gain reduction control is to be executed, the gear ratio feedback gain reduction control is executed. ) can be changed. Specifically, in the gear ratio feedback gain reduction control, it is determined whether the actual gear ratio is larger than a predetermined gear ratio, and if the actual gear ratio is smaller than the predetermined gear ratio, the actual gear ratio is set to the predetermined gear ratio. The value of the feedback gain of the gear ratio in feedback control is set to a smaller value than when the feedback gain is larger. The PID feedback control amount output from the gear ratio feedback PID control unit M2 has noise components removed by a filter 94, and is provided to the oil pressure supply mechanism 46 as a control value for oil pressure.

In the present embodiment, when the shift controller 90 determines that a malfunction such as a failure has occurred in the NDR sensor (rotation speed sensor) 72, the gear ratio feedback gain reduction is performed by the gear ratio feedback gain reduction control execution determining unit M3. A decision is made to execute the control. Fig. 4 shows changes in engine speed (NE), drive pulley rotation speed (NDR), CVT26 ratio (R), and feedback oil pressure (P) when gear ratio feedback gain reduction control is performed and when it is not performed. This is a timing chart. Regarding the changes in each value shown in the graph of the same figure, the solid line shows the change in value when the gear ratio feedback gain reduction control is not performed (no control), and the value when the gear ratio feedback gain reduction control is performed (with control). The change in is shown by the dotted line. Further, the detected value of the NDR sensor 72 and the calculated value based on the detected value are shown by a dashed line.

First, a case will be described in which the speed ratio feedback gain reduction control is not performed when a malfunction such as a failure occurs in the NDR sensor 72 (a case where normal speed change control using a conventional method is performed). In this case, if a malfunction such as a failure occurs in the NDR sensor 72 at time t1, the detected value of the drive pulley rotation speed (NDR) detected by the NDR sensor 72 becomes lower than the actual rotation speed, and as a result, A difference (difference) occurs between the ratio (actual ratio) of the CVT 26 calculated based on the detected value of the NDR sensor 72 and the target ratio. Then, in order to compensate for the difference between the actual ratio and the target ratio, control is performed to increase the feedback oil pressure and change the ratio of the CVT 26 to a low side ratio (a large gear ratio). As a result, the ratio of the CVT 26 is shifted to a low ratio, thereby increasing the rotation speed of the engine 10. Because the NDR sensor 72 is malfunctioning, the normal drive pulley rotation speed cannot be calculated, and the shift continues to the low ratio, eventually reaching the maximum ratio that the CVT 26 can mechanically (structurally) take. (The lowest ratio: LOW end ratio).

Next, a case where the gear ratio feedback gain reduction control is performed when the NDR sensor 72 is out of order (a case where the speed change control according to the method of the present invention is performed) will be described. In this case, if a malfunction such as a failure occurs in the NDR sensor 72 at time t1, the detected value of the drive pulley rotation speed (NDR) detected by the NDR sensor 72 becomes lower than the actual rotation speed, which causes the shift The ratio feedback gain reduction control execution determination unit M3 determines to execute the gear ratio feedback gain reduction control. As a result, the gear ratio feedback gain is reduced by the gear ratio feedback gain reduction control (the value of the feedback gain is switched to a lower value), thereby suppressing an increase in the feedback oil pressure and causing the ratio of the CVT 26 to be excessively shifted to the low side. It is possible to avoid performing control to change the gear to a ratio of . This prevents the actual ratio of the CVT 26 from increasing excessively, thereby preventing the drive pulley rotational speed (actual rotational speed) from increasing excessively.

That is, when the detected value of the NDR sensor 72 transitions further to the OD side (smaller gear ratio) than the minimum ratio that the CVT 26 can mechanically (structurally) take (OD end ratio shown in FIG. 4), It is determined that a malfunction such as a failure has occurred in the NDR sensor 72, and an excessive shift to a low ratio can be suppressed. As a result, it is possible to prevent an excessive shift to a low ratio until the failure of the NDR sensor 72 is determined, so that the vehicle behavior can be controlled so that the vehicle can be moved safely during that time. It becomes possible.

Here, the determination to execute the gear ratio feedback gain reduction control by the shift controller 90 will be explained. FIG. 5 is a graph (shift map) showing an example of the shift characteristics of the CVT 26. As shown in FIG. The gear ratio of the CVT 26 is given by the ratio of the input rotation speed (the rotation speed of the drive pulley 26a) to the output rotation speed (the rotation speed of the driven pulley 26b). In the graph of the figure, the horizontal axis indicates the vehicle speed V (parameter corresponding to the output rotation speed of the CVT 26). Further, the vertical axis indicates a set value or a target value (hereinafter simply referred to as "NDR set value") of the input rotation speed (drive pulley rotation speed NDR) of the CVT 26. In this graph, a line L1 at the LOW end is shown as a slope indicating the maximum speed ratio, and a line L2 at the overdrive (OD) end is shown as a slope representing the minimum speed ratio. Here, to simplify the explanation, the shift characteristics for the accelerator opening degrees AP1 to AP4 are illustrated (herein, it is assumed that AP4>AP3>AP2>AP1). Line L3 (APOFF) indicated by a dotted line in the graph of the same figure indicates a state in which the accelerator pedal 56 is not operated by the driver (accelerator off, that is, the accelerator opening AP detected by the accelerator opening sensor 56a is substantially This is the zero line.

For example, when the accelerator opening AP changes at a certain vehicle speed V (with the vehicle speed V being constant), the shift controller 90 changes the NDR setting value to a value corresponding to the accelerator opening AP, and changes the input rotation speed NDR of the CVT 26. The CVT 26 is controlled (changes the gear ratio) so that the NDR follows the changed NDR setting value. Further, for example, when the vehicle speed V changes at a certain accelerator opening AP (assuming the accelerator opening AP is constant), the shift controller 90 changes the NDR setting value to a value corresponding to the vehicle speed V, and changes the input rotation speed of the CVT 26. The CVT 26 is controlled so that the NDR follows the changed NDR setting value.

In the normal driving mode of the vehicle, the CVT 26 is controlled according to the speed change map shown in FIG. 5 (the speed ratio of the CVT 26 is changed based on the accelerator opening AP and the vehicle speed V during driving). For ease of explanation, shift characteristics for four accelerator openings AP1 to AP4 are illustrated here, but in reality, many more shift characteristics may be prepared in advance or obtained through arithmetic processing.

The ratio (speed ratio) of the CVT 26 changes continuously between the LOW end ratio line L1 and the OD end ratio line L2 in the graph, and normal operation (normal driving mode) cannot be performed within this range. can. The LOW end ratio (line L1) here is the maximum ratio that the CVT 26 can take due to its structure (mechanically settable), and the OD end ratio (line L2) is the maximum ratio that the CVT 26 can take due to its structure. This is the smallest possible (mechanically settable) ratio. Therefore, the calculated value or theoretical value by the shift controller 90 is a value in a range where the ratio of the CVT 26 is larger than the LOW end ratio (a range on the lower vehicle speed side or higher rotation speed side than line L1 in the graph) or at the OD end. Although the value may be in a range smaller than the ratio (range on the higher vehicle speed side or lower rotation speed side than line L2 in the graph), the ratio that can actually be used with the CVT26 is the LOW end. This is the range between the ratio line L1 and the OD end ratio line L2.

Furthermore, even if the ratio of CVT26 is in a range larger than the OD end ratio (the upper side of line L2 in the graph, that is, the region on the low vehicle speed side or high rotational speed side), it is lower than the line of accelerator opening AP1. The range where the ratio is small (the lower side of line AP1 in the graph, that is, the area on the high vehicle speed side and low rotation side) is a ratio area that is not used for control purposes from the viewpoint of stability and safety of vehicle behavior. be. That is, this region S1 (the shaded region of the graph) is a range in which the target ratio value and the actual ratio value by the shift controller 90 are not substantially set.

In the graph of FIG. 5, in the low vehicle speed region below vehicle speed V1, the APOFF line L3 does not match the AP1 line and deviates to the low side from the AP1 line. In the area, the ratio on line L3 (APOFF) is set to be a larger ratio (low side ratio) than the ratio on AP1. On the other hand, in the region of vehicle speed V1 or higher, the APOFF line L3 coincides with the AP1 line, and in the region (S1) of the gear ratio that is not used for control in the target shift map, the accelerator opening AP is substantially This is a region below the gear ratio in the fully closed state. The reason for this setting is that by shifting the ratio to the low side in the low vehicle speed region below vehicle speed V1, the low holding performance when the vehicle is stopped (hydraulic pressure in the hydraulic circuit when the vehicle is stopped) is increased. The purpose of this is to improve the performance of preventing the ratio from dropping and shifting to the high side) and the responsiveness when re-accelerating.

In addition, in the graph of FIG. 5 (target shift map), the gear ratio area (S1) that is not used for control is a lock-up area when the vehicle speed is below the predetermined vehicle speed V1 and the lock-up clutch 24c of the torque converter 24 is off. It is set as a value on the target shift map based on the accelerator opening AP and vehicle speed V when the clutch 24c is on.

In the present embodiment, the shift controller 90 performs the above-mentioned speed ratio feedback gain reduction control when either Condition 1 or Condition 2 below is satisfied.

[Condition 1]
The shift controller 90 generates a gear ratio feedback gain when the ratio of the CVT 26 calculated based on the detected value of the NDR sensor 72 is a smaller ratio (ratio within region S2) than the OD end ratio (line L2) (condition 1). Implement reduction control.

[Condition 2]
The shift controller 90 performs the gear ratio feedback gain reduction control when the ratio of the CVT 26 calculated based on the detected value of the NDR sensor 72 is within the region S1 (condition 2). That is, in an area where the vehicle speed is V1 or higher, the gear ratio feedback gain reduction control is performed when the ratio of the CVT 26 is less than line L3 (APOFF) and the accelerator opening AP1, and in an area where the vehicle speed is less than V1, the ratio of the CVT 26 is When the ratio is less than or equal to the accelerator opening AP1, the gear ratio feedback gain reduction control is performed.

Furthermore, in the present embodiment, the shift controller 90 determines that the road surface on which the vehicle is traveling is a low friction coefficient road (low μ road) even if either of the above conditions 1 or 2 is met. If the determination is made, the gear ratio feedback gain reduction control is not performed. Although illustration and detailed explanation are omitted, the low friction coefficient road determination unit that determines whether the road surface on which the vehicle is traveling is a low friction coefficient road (low μ road), for example, A driving force detection unit that detects the driving force of the wheels 12, a slip rate detection unit that detects the slip rate of the driving wheels 12, and a road surface μ based on the correlation between the driving force of the driving wheels 12 and the slip rate. The low-μ road determination process by this low-friction coefficient road determination section uses a known method such as that disclosed in Japanese Patent Application Laid-Open No. 8-300964, to determine whether the vehicle is The judgment is made based on whether or not the traveling road is a slippery (low coefficient of friction μ) road.

As explained above, the shift controller 90 included in the vehicle of the present embodiment is configured to control the actual gear ratio when the ratio (actual gear ratio) of the CVT 26 calculated based on the detected value of the NDR sensor 72 is less than or equal to the predetermined gear ratio. Gear ratio feedback gain reduction control is performed to set a value of a feedback gain of a gear ratio in hydraulic feedback control to a smaller value than when the gear ratio is larger than a predetermined gear ratio.

If the ratio (actual gear ratio) of the CVT 26 calculated based on the detected value of the NDR sensor 72 is less than the predetermined gear ratio, there is a problem such as a failure in the NDR sensor 72 that detects the rotation speed of the drive pulley 26a of the CVT 26. There is a high possibility that this has occurred. Therefore, by performing gear ratio feedback gain reduction control that sets the value of the feedback gain of the gear ratio in feedback control to a smaller value than when the actual gear ratio is larger than the predetermined gear ratio, CVT2 It is possible to prevent the ratio (speed ratio) from being excessively shifted to a low side (low speed side) ratio.

Further, according to the control by the shift controller 90 of this embodiment, failure of the NDR sensor 72 can be appropriately determined and the CVT 26 can be activated without increasing the number of installed rotational speed sensors or performing complicated control. Since it is possible to prevent the ratio (speed ratio) from being shifted excessively to a low side (low speed side) ratio, it is possible to prevent the vehicle from increasing in cost, while also preventing the vehicle from being shifted excessively to the low side (low speed side). This makes it possible to ensure the stability of the vehicle's behavior until it is stopped in a safe location.

The above-mentioned predetermined gear ratio may be a gear ratio that the CVT 26 can take structurally or a gear ratio smaller than that, and in this embodiment, the smallest gear ratio (OD end gear ratio ).

According to this configuration, the predetermined gear ratio is the smallest gear ratio (OD end gear ratio) that the CVT 26 can take structurally, and when the actual gear ratio is less than or equal to this predetermined gear ratio, the NDR sensor 72 There is a high possibility that a malfunction such as a breakdown has occurred. Therefore, it is possible to appropriately determine that a problem such as a failure has occurred in the NDR sensor 72 and perform gear ratio feedback gain reduction control, so that the behavior of the vehicle can be controlled until the vehicle is stopped in a safe place. It becomes possible to ensure stability.

Further, in the present embodiment, the shift controller 90 has a target speed change map for obtaining a target speed change ratio of the CVT 26, and a target speed change ratio (calculated based on the detection value of the NDR sensor 72) on this target speed change map. The above-mentioned transmission ratio feedback gain Perform reduction control.

According to this configuration, if the target gear ratio on the target gear change map is within the range of gear ratios that are not used for control, or is larger than the smallest gear ratio that the CVT 26 can take structurally, , there is a high possibility that a malfunction such as a failure has occurred in the NDR sensor 72. Therefore, since it is possible to appropriately determine that a problem such as a failure has occurred in the NDR sensor 72 and perform gear ratio feedback gain reduction control, the behavior of the vehicle can be controlled until the vehicle is stopped in a safe place. It becomes possible to ensure stability.

Furthermore, in the present embodiment, when the vehicle speed is equal to or higher than the predetermined vehicle speed V1, the region S1, which is a region of the gear ratio that is not used for control in the target shift map, corresponds to the shift when the accelerator opening AP is substantially in the fully closed (off) state. This is the area below the ratio (line L3).

Further, in the present embodiment, in the region S1, which is a region of the gear ratio not used for control in the target shift map, when the vehicle speed is less than or equal to the predetermined vehicle speed and the lockup clutch 24c is off, the lockup clutch 24c is in the on state. The target speed change map is set based on the accelerator opening degree AP and the vehicle speed V.

In a low vehicle speed state where the vehicle speed V is less than or equal to the predetermined vehicle speed V1, the lock-up clutch 24c of the torque converter 24 mounted on the vehicle is in the off state. There is a risk that a temporary change in rotational speed (gear ratio) may occur. Therefore, when the vehicle speed is below the predetermined vehicle speed V1 and the lock-up clutch 24c is off, the torque is set using a shift map based on the accelerator opening AP and the vehicle speed V with the lock-up clutch 24c on. It is possible to appropriately determine whether a problem such as a failure has occurred in the NDR sensor 72 without being affected by a temporary change in the drive pulley rotation speed caused by the lock-up clutch 24c of the converter 24 being turned off. That's what I do.

Furthermore, in the present embodiment, the shift controller 90 does not perform the above-mentioned speed ratio feedback gain reduction control when it is determined that the road surface on which the vehicle is traveling is a low friction coefficient road.

When the road surface on which the vehicle is running has a low coefficient of friction, sudden fluctuations may occur in the wheel speed or vehicle speed or their acceleration due to slipping of the drive wheels 12, etc. , there is a possibility that a temporary change in the rotation speed (speed ratio) of the CVT 26 detected by the NDR sensor 72 may occur. Therefore, if the road surface on which the vehicle is running is a low friction coefficient road, by not performing gear ratio feedback gain reduction control, it is possible to prevent the vehicle from running on a low friction coefficient road. It is possible to appropriately determine whether a malfunction such as a failure has occurred in the NDR sensor 72 without being affected by a temporary change in the rotational speed of the CVT 26 caused by the above.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications may be made within the scope of the claims and technical ideas described in the specification and drawings. Variations are possible. For example, in the above embodiment, the rotation speed sensor subject to failure determination is the NDR sensor 72 that detects the rotation speed of the drive pulley 26a. The rotation speed sensor may be an NDN sensor 74 that detects the rotation speed of the driven pulley 26b.

1 Automatic transmission 10 Engine 12 Drive wheel 16 DBW mechanism 20 Injector 22 Crankshaft 24 Torque converter 24a Pump/impeller 24b Turbine runner 24c Lock-up clutch 26 Transmission mechanism (CVT)
26a Drive pulley 26b Driven pulley 26c Belt (power transmission member)
28 Forward/forward switching device 32 Differential 44 Range selector 44a Range selector switch 46 Hydraulic pressure supply mechanism 50 Engine speed sensor 54 Throttle opening sensor 56 Accelerator pedal 56a Accelerator opening sensor 66 Engine controller 70 NT sensor (speed sensor)
72 NDR sensor (rotation speed sensor)
74 NDN sensor (rotation speed sensor)
76 Vehicle speed sensor 82 Oil pressure sensor 84 Oil temperature sensor 90 Shift controller MS Main shaft CS Counter shaft SS Secondary shaft M1 Target gear ratio determination unit M2 Gear ratio feedback PID control unit M3 Gear ratio feedback gain reduction control execution determination unit

Claims (10)

A drive pulley that rotates when the driving force from the vehicle's drive source is transmitted, a driven pulley that transmits the driving force accompanying the rotation to the output side, and a power transmission that is wound between the drive pulley and the driven pulley. A continuously variable transmission that includes a member, and that changes the number of revolutions of the drive pulley steplessly and transmits it to the driven pulley by changing the pulley widths of the drive pulley and the driven pulley;
a rotation speed sensor that detects the rotation speed of the drive pulley or the driven pulley;
a hydraulic pressure supply device that supplies hydraulic pressure applied to the drive pulley;
A control device for a continuously variable transmission for a vehicle, comprising: a control device that controls the supply of hydraulic pressure by the hydraulic pressure supply device;
The control device performs feedback control of the oil pressure so that the actual gear ratio of the continuously variable transmission calculated based on the detected value of the rotation speed sensor becomes a target gear ratio,
When the actual gear ratio is less than or equal to a predetermined gear ratio, a gear ratio that sets a feedback gain value of the gear ratio in the feedback control to a smaller value than when the actual gear ratio is larger than the predetermined gear ratio. A control device for a continuously variable transmission for a vehicle, characterized by performing feedback gain reduction control. The control device for a continuously variable transmission for a vehicle according to claim 1, wherein the predetermined gear ratio is the smallest gear ratio that the continuously variable transmission can take structurally or a smaller gear ratio. . The control device has a target gear change map for obtaining the target gear ratio,
If the target gear ratio on the target gear change map is within a range of gear ratios that are not used for control and is larger than the smallest gear ratio that the continuously variable transmission can take structurally, the gear ratio 3. The control device for a continuously variable transmission for a vehicle according to claim 1, wherein the control device performs feedback gain reduction control. Vehicle speed detection means for detecting the vehicle speed of the vehicle;
comprising: an accelerator operator operated by a driver of the vehicle; and an accelerator opening detection means for detecting an accelerator opening due to the operation of the accelerator operator;
4. The continuously variable transmission for a vehicle according to claim 3, wherein the range of gear ratios not used for control in the target gear shift map is set based on the accelerator opening degree and the vehicle speed (V). Control device. 5. The vehicle control system according to claim 4, wherein the range of gear ratios that are not used for control in the target gear shift map is a range that is equal to or lower than the gear ratio when the accelerator opening is substantially in a fully closed state. Control device for gear transmission. The vehicle is equipped with a torque converter equipped with a lock-up clutch,
When the vehicle is at a predetermined speed or lower and the lock-up clutch is off, the range of speed ratios that are not used for control in the target speed change map is based on the accelerator opening degree and the vehicle speed when the lock-up clutch is on. 4. The control device for a continuously variable transmission for a vehicle according to claim 3, wherein the value is set based on the target shift map. 3. The control device for a continuously variable transmission for a vehicle according to claim 2, wherein the predetermined speed ratio is the smallest possible speed ratio due to the structure of the continuously variable transmission. 4. The control device for a continuously variable transmission for a vehicle according to claim 3, wherein the predetermined speed ratio is the smallest possible speed ratio due to the structure of the continuously variable transmission. comprising a low friction coefficient road determining means for determining whether or not the road surface on which the vehicle is traveling is a low friction coefficient road where the friction coefficient of the road surface is equal to or less than a predetermined value;
The control device is characterized in that when the low friction coefficient road determining means determines that the road surface on which the vehicle is traveling is a low friction coefficient road, the control device does not perform the gear ratio feedback gain reduction control. The control device for a continuously variable transmission for a vehicle according to claim 2. comprising a low friction coefficient road determining means for determining whether or not the road surface on which the vehicle is traveling is a low friction coefficient road where the friction coefficient of the road surface is equal to or less than a predetermined value;
The control device is characterized in that when the low friction coefficient road determining means determines that the road surface on which the vehicle is traveling is a low friction coefficient road, the control device does not perform the gear ratio feedback gain reduction control. The control device for a continuously variable transmission for a vehicle according to claim 3.

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