JP2009243492A - Control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately control the input shaft rotational speed NI of an automatic transmission. <P>SOLUTION: In this control device for the automatic transmission, an ECT_ECU performs a program including: a step (S102) of downshifting so that a B3 brake (or a B1 brake) is released and an engagement force of a C2 clutch is controlled to be reduced to a predetermined target value, and after that, the C2 clutch is disengaged, and a C1 clutch and the B1 brake (or the B3 brake) are controlled to be engaged with each other; and steps (S112, 122) of correcting the target value of the engagement force of the C2 clutch according to a rate of a change in turbine rotational speed NT (input shaft rotational speed NI of the automatic transmission). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an automatic transmission, and more particularly to a technique for correcting a target value of an engagement force of an engagement element of an automatic transmission in accordance with a change rate of an input shaft rotational speed of the automatic transmission.

  2. Description of the Related Art Conventionally, there is known an automatic transmission that changes gears by changing a combination of engaging elements among engaging elements such as a clutch and a brake. In the automatic transmission, there is a case where a so-called clutch-to-clutch shift is performed in which any engagement element is released and another engagement element is engaged. In the clutch-to-clutch shift, for example, when the engagement element is engaged in a state where the input shaft rotational speed of the automatic transmission is too high or too low, a shock may occur. In order to reduce the shock that may occur at the time of shifting, it is desirable to suitably control the input shaft rotational speed of the automatic transmission.

  Japanese Patent Laid-Open No. 2004-183757 discloses that the amount of decrease in the input shaft rotation speed is reduced based on the amount of decrease in the input shaft rotation speed of the automatic transmission during a clutch-to-clutch downshift. Thus, a shift control device that corrects the engagement pressure of a hydraulic friction engagement device (engagement element) operated for clutch-to-clutch downshift by learning control is disclosed.

According to the speed change control device described in this publication, when the clutch-to-clutch downshift is being performed while the vehicle is decelerating, a drop in engine rotation speed is automatically suppressed, and a shift shock or shift time caused by the drop is suppressed. The delay is preferably eliminated.
JP 2004-183757 A

  However, Japanese Patent Laid-Open No. 2004-183757 is premised on a clutch-to-clutch shift in which only one engaging element to be engaged is changed. Therefore, there is no description on how to control the engagement force of the engagement element in a shift made by changing both of the two engagement elements to be engaged. for that reason. There is room for further improvement in order to suitably control the input shaft speed of the automatic transmission.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to reduce the input shaft rotational speed of an automatic transmission in a shift made by changing two engaging elements to be engaged. It is an object to provide a control device for an automatic transmission that can be suitably controlled.

  In the control device for an automatic transmission according to the first invention, the first gear stage is formed by engaging the first engagement element and the second engagement element, and the second engagement element and the second engagement element The second gear stage is formed by engaging the three engagement elements, and the third gear stage is formed by engaging the third engagement element and the fourth engagement element. Is the control device of the machine. The control device determines whether or not to perform a shift from the third gear to the first gear, and determines to perform a shift from the third gear to the first gear. In this case, the fourth engagement element is released, and after the engagement force of the third engagement element is reduced to a predetermined target value, the third engagement element is released and the first engagement element is released. Control means for controlling the engagement element and the second engagement element to engage with each other, and detecting the rate of change of the input shaft rotation speed after the engagement force of the third engagement element is reduced to the target value And a correcting means for correcting the target value in accordance with the rate of change of the input shaft rotational speed.

  According to this configuration, when it is determined that the shift from the third gear stage to the first gear stage is performed, the fourth engagement element is engaged before engaging the first engagement element and the second engagement element. Control is performed such that the engagement element is released and the engagement force of the third engagement element is reduced to a predetermined target value. As a result, one of the two engagement elements forming the gear stage before the shift can be released, and only the other can have an engagement force. By releasing one of the engaging elements, the shift can be started quickly. The target value of the engagement force of the third engagement element is corrected according to the rate of change of the input shaft rotation speed after the engagement force of the third engagement element has decreased to the target value. For example, when the change rate of the input shaft rotational speed is large, the target value of the engagement force is corrected so as to increase. As a result, the force (torque) acting on the input shaft in the automatic transmission can be increased. Therefore, the change rate of the input shaft rotation speed can be reduced. When the change rate of the input shaft speed is small, the target value of the engagement force is corrected so as to be small. As a result, the force acting on the input shaft inside the automatic transmission can be reduced. Therefore, the rate of change of the input shaft rotation speed can be increased. As a result, it is possible to provide a control device for an automatic transmission that can suitably control the input shaft rotation speed of the automatic transmission in a shift made by changing two engaging elements to be engaged.

  In the control apparatus for an automatic transmission according to the second invention, in addition to the configuration of the first invention, the correction means has a larger target value when the rate of change of the input shaft rotational speed is large than when it is small. Means for correcting as follows.

  According to this configuration, when the rate of change of the input shaft rotational speed is large, the target value is corrected to be larger than when it is small. Thereby, when the change rate of the input shaft rotation speed is excessive, the change rate of the input shaft rotation speed can be reduced so as to be an appropriate value.

  In the automatic transmission control apparatus according to the third aspect of the invention, in addition to the configuration of the first aspect, the correcting means provides a target value when the rate of change of the input shaft rotational speed is greater than a predetermined target rate of change. Is included, and when the rate of change of the input shaft rotational speed is smaller than a predetermined target rate of change, means for correcting the target value to be reduced is included.

  According to this configuration, when the change rate of the input shaft rotation speed is larger than a predetermined target change rate, the target value of the engagement force is increased. When the change rate of the input shaft rotational speed is smaller than a predetermined target change rate, the target value of the engagement force is made smaller. Thereby, it is possible to control so that the difference between the actual change rate of the input shaft rotation speed and the target change rate becomes small. Therefore, the input shaft rotation speed of the automatic transmission can be suitably controlled.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A vehicle equipped with a control device according to an embodiment of the present invention will be described with reference to FIG. This vehicle is an FF (Front engine Front drive) vehicle. A vehicle other than FF may be used.

The vehicle includes an engine 1000, an automatic transmission 2000, a planetary gear unit 3000 constituting a part of the automatic transmission 2000, a hydraulic circuit 4000 constituting a part of the automatic transmission 2000, a differential gear 5000, a drive shaft 6000, Front wheel 7000 and ECU (Electronic Control Unit) 8000 are included. The control device according to the present embodiment is
For example, it is realized by executing a program recorded in a ROM (Read Only Memory) 8300 of an ECT (Electronic Controlled Transmission) _ECU 8200. Note that a program executed by the ECT_ECU 8200 may be recorded on a recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc) and distributed to the market.

  Engine 1000 is an internal combustion engine that burns a mixture of fuel and air injected from an injector (not shown) in a combustion chamber of a cylinder. The piston in the cylinder is pushed down by the combustion, and the crankshaft is rotated. In addition to engine 1000, a motor may be used as a power source.

  Automatic transmission 2000 is connected to engine 1000 via torque converter 3200. Automatic transmission 2000 shifts the rotational speed of the crankshaft to a desired rotational speed by forming a desired gear stage.

  The output gear of automatic transmission 2000 is meshed with differential gear 5000. A drive shaft 6000 is connected to the differential gear 5000 by spline fitting or the like. Power is transmitted to the left and right front wheels 7000 via the drive shaft 6000.

  The ECU 8000 includes an air flow meter 8002, a position switch 8006 of a shift lever 8004, an accelerator opening sensor 8010 of an accelerator pedal 8008, a pedaling force sensor 8014 of a brake pedal 8012, a throttle opening sensor 8018 of an electronic throttle valve 8016, An engine speed sensor 8020, an input shaft speed sensor 8022, an output shaft speed sensor 8024, and an oil temperature sensor 8026 are connected via a harness or the like.

  Air flow meter 8002 detects the amount of air taken into engine 1000 and transmits a signal representing the detection result to ECU 8000. The position (position) of shift lever 8004 is detected by position switch 8006, and a signal representing the detection result is transmitted to ECU 8000. Corresponding to the position of the shift lever 8004, the gear stage of the automatic transmission 2000 is automatically formed. Further, a manual shift mode in which the driver can select an arbitrary gear stage may be selected according to the driver's operation.

  Accelerator opening sensor 8010 detects the opening of accelerator pedal 8008 and transmits a signal representing the detection result to ECU 8000. The pedaling force sensor 8014 detects the pedaling force of the brake pedal 8012 (the force with which the driver steps on the brake pedal 8012), and transmits a signal representing the detection result to the ECU 8000.

  The throttle opening sensor 8018 detects the opening of the electronic throttle valve 8016 whose opening is adjusted by the actuator, and transmits a signal representing the detection result to the ECU 8000. Electronic throttle valve 8016 adjusts the amount of air taken into engine 1000 (output of engine 1000).

  Instead of or in addition to the electronic throttle valve 8016, the amount of air drawn into the engine 1000 can be reduced by changing the lift amount of the intake valve (not shown) or the exhaust valve (not shown) and the opening / closing phase. You may make it adjust.

  Engine rotation speed sensor 8020 detects the rotation speed of the output shaft (crankshaft) of engine 1000 and transmits a signal representing the detection result to ECU 8000. Input shaft rotational speed sensor 8022 detects input shaft rotational speed NI of automatic transmission 2000 (turbine rotational speed NT of torque converter 3200), and transmits a signal representing the detection result to ECU 8000. Output shaft rotational speed sensor 8024 detects output shaft rotational speed NO of automatic transmission 2000 and transmits a signal representing the detection result to ECU 8000. The vehicle speed is calculated (detected) from the output shaft rotational speed NO.

  Oil temperature sensor 8026 detects the temperature (oil temperature) of oil (ATF: Automatic Transmission Fluid) used for the operation and lubrication of automatic transmission 2000, and transmits a signal indicating the detection result to ECU 8000.

  The ECU 8000 includes an air flow meter 8002, a position switch 8006, an accelerator opening sensor 8010, a pedaling force sensor 8014, a throttle opening sensor 8018, an engine speed sensor 8020, an input shaft speed sensor 8022, an output shaft speed sensor 8024, and an oil temperature sensor. On the basis of a signal sent from 8026 and the like, a map and a program stored in the ROM 8300, the devices are controlled so that the vehicle is in a desired traveling state.

  In the present embodiment, ECU 8000, when shift lever 8004 is in the D (drive) position and D (drive) range is selected as the shift range of automatic transmission 2000, out of 1st to 6th gears The automatic transmission 2000 is controlled so that any one of the gear positions is formed. The automatic transmission 2000 can transmit the driving force to the front wheels 7000 by forming any one of the first to sixth gears. In the D range, it may be possible to form a higher gear than the sixth gear, that is, a seventh gear or an eighth gear. The gear stage to be formed is determined based on a shift diagram created in advance by experiments or the like using the vehicle speed and the accelerator opening as parameters.

  As shown in FIG. 1, ECU 8000 includes an engine ECU 8100 that controls engine 1000 and an ECT_ECU 8200 that controls automatic transmission 2000.

Engine ECU 8100 and ECT_ECU 8200 are configured to be able to transmit and receive signals to and from each other. In this embodiment, ECT_E from engine ECU 8100
A signal representing the accelerator opening, a signal representing the output torque TEKL converted from the intake air amount, and the like are transmitted to CU8200. From ECT_ECU 8200 to engine ECU 8100, a signal indicating a torque request amount, a torque down amount, a torque up amount, and the like determined as torque to be output by engine 1000 is transmitted.

  The planetary gear unit 3000 will be described with reference to FIG. Planetary gear unit 3000 is connected to a torque converter 3200 having an input shaft 3100 coupled to a crankshaft. Planetary gear unit 3000 includes a first set 3300 of planetary gear mechanisms, a second set 3400 of planetary gear mechanisms, an output gear 3500, a B1 brake 3610, a B2 brake 3620 and a B3 brake 3630 fixed to gear case 3600, and C1. Clutch 3640 and C2 clutch 3650, and one-way clutch F3660 are included.

  The first set 3300 is a single pinion type planetary gear mechanism. First set 3300 includes sun gear S (UD) 3310, pinion gear 3320, ring gear R (UD) 3330, and carrier C (UD) 3340.

  Sun gear S (UD) 3310 is coupled to output shaft 3210 of torque converter 3200. Pinion gear 3320 is rotatably supported by carrier C (UD) 3340. Pinion gear 3320 is in mesh with sun gear S (UD) 3310 and ring gear R (UD) 3330.

  Ring gear R (UD) 3330 is fixed to gear case 3600 by B3 brake 3630. Carrier C (UD) 3340 is fixed to gear case 3600 by B1 brake 3610.

  The second set 3400 is a Ravigneaux type planetary gear mechanism. The second set 3400 includes a sun gear S (D) 3410, a short pinion gear 3420, a carrier C (1) 3422, a long pinion gear 3430, a carrier C (2) 3432, a sun gear S (S) 3440, and a ring gear R. (1) (R (2)) 3450.

  Sun gear S (D) 3410 is coupled to carrier C (UD) 3340. Short pinion gear 3420 is rotatably supported by carrier C (1) 3422. Short pinion gear 3420 is in mesh with sun gear S (D) 3410 and long pinion gear 3430. Carrier C (1) 3422 is coupled to output gear 3500.

  Long pinion gear 3430 is rotatably supported by carrier C (2) 3432. Long pinion gear 3430 is in mesh with short pinion gear 3420, sun gear S (S) 3440, and ring gear R (1) (R (2)) 3450. Carrier C (2) 3432 is coupled to output gear 3500.

  Sun gear S (S) 3440 is coupled to output shaft 3210 of torque converter 3200 by C1 clutch 3640. Ring gear R (1) (R (2)) 3450 is fixed to gear case 3600 by B2 brake 3620 and connected to output shaft 3210 of torque converter 3200 by C2 clutch 3650. The ring gear R (1) (R (2)) 3450 is connected to the one-way clutch F3660, and cannot rotate when the first gear is driven.

  Engagement of C2 clutch 3650 restricts rotation of rotating member 3212 and ring gear R (1) (R (2)) 3450 connected to the input shaft of automatic transmission 2000, that is, output shaft 3210 of torque converter 3200. The Further, the rotation of the rotating member 3212 is restricted by the engagement of the C1 clutch 3640. Torque is transmitted from the input shaft of automatic transmission 2000 to rotating member 3212.

  The one-way clutch F3660 is provided in parallel with the B2 brake 3620. That is, the outer race of the one-way clutch F3660 is fixed to the gear case 3600, and the inner race is connected to the ring gear R (1) (R (2)) 3450 via the rotation shaft.

  FIG. 3 shows an operation table showing the relationship between each gear position and the operation state of each clutch and each brake. By operating each brake and each clutch with the combinations shown in this operation table, a forward gear stage of 1st to 6th speed and a reverse gear stage are formed.

  The main part of the hydraulic circuit 4000 will be described with reference to FIG. The hydraulic circuit 4000 is not limited to the one described below.

  The hydraulic circuit 4000 includes an oil pump 4004, a primary regulator valve 4006, a manual valve 4100, a solenoid modulator valve 4200, an SL1 linear solenoid (hereinafter referred to as SL (1)) 4210, and an SL2 linear solenoid (hereinafter referred to as “the solenoid valve”). 4220, SL3 linear solenoid (hereinafter referred to as SL (3)) 4230, SL4 linear solenoid (hereinafter referred to as SL (4)) 4240, and SLT linear solenoid (hereinafter referred to as SL (2)). , SLT) 4300 and a B2 control valve 4500.

  Oil pump 4004 is connected to the crankshaft of engine 1000. As the crankshaft rotates, the oil pump 4004 is driven to generate hydraulic pressure. The hydraulic pressure generated by the oil pump 4004 is regulated by the primary regulator valve 4006 to generate a line pressure.

  Primary regulator valve 4006 operates using the throttle pressure regulated by SLT 4300 as a pilot pressure. The line pressure is supplied to the manual valve 4100 via the line pressure oil passage 4010.

  Manual valve 4100 includes a drain port 4105. From the drain port 4105, the oil pressure in the D range pressure oil passage 4102 and the R range pressure oil passage 4104 is discharged. When the spool of the manual valve 4100 is in the D position, the line pressure oil passage 4010 and the D range pressure oil passage 4102 are communicated, and hydraulic pressure is supplied to the D range pressure oil passage 4102. At this time, the R range pressure oil passage 4104 and the drain port 4105 are communicated, and the R range pressure of the R range pressure oil passage 4104 is discharged from the drain port 4105.

  When the spool of the manual valve 4100 is in the R position, the line pressure oil passage 4010 and the R range pressure oil passage 4104 are communicated, and the oil pressure is supplied to the R range pressure oil passage 4104. At this time, the D range pressure oil passage 4102 and the drain port 4105 are communicated, and the D range pressure in the D range pressure oil passage 4102 is discharged from the drain port 4105.

  When the spool of the manual valve 4100 is in the N position, both the D range pressure oil passage 4102 and the R range pressure oil passage 4104 are connected to the drain port 4105, and the D range pressure and R of the D range pressure oil passage 4102 are communicated. The R range pressure of the range pressure oil passage 4104 is discharged from the drain port 4105.

  The hydraulic pressure supplied to the D range pressure oil passage 4102 is finally supplied to the B1 brake 3610, the B2 brake 3620, the C1 clutch 3640, and the C2 clutch 3650. The hydraulic pressure supplied to the R range pressure oil passage 4104 is finally supplied to the B2 brake 3620.

  The solenoid modulator valve 4200 adjusts the hydraulic pressure (solenoid modulator pressure) supplied to the SLT 4300 to a constant pressure using the line pressure as the original pressure.

  SL (1) 4210 regulates the hydraulic pressure supplied to the C1 clutch 3640. SL (2) 4220 regulates the hydraulic pressure supplied to C2 clutch 3650. SL (3) 4230 regulates the hydraulic pressure supplied to the B1 brake 3610. SL (4) 4240 regulates the hydraulic pressure supplied to the B3 brake 3630.

  The SLT 4300 adjusts the solenoid modulator pressure in accordance with a control signal from the ECU 8000 based on the accelerator opening detected by the accelerator opening sensor 8010, and generates a throttle pressure. The throttle pressure is supplied to the primary regulator valve 4006 via the SLT oil passage 4302. The throttle pressure is used as a pilot pressure for the primary regulator valve 4006.

  SL (1) 4210, SL (2) 4220, SL (3) 4230, SL (4) 4240, and SLT 4300 are controlled by a control signal transmitted from ECT_ECU 8200.

  The B2 control valve 4500 selectively supplies hydraulic pressure from one of the D range pressure oil passage 4102 and the R range pressure oil passage 4104 to the B2 brake 3620. A D range pressure oil passage 4102 and an R range pressure oil passage 4104 are connected to the B2 control valve 4500. The B2 control valve 4500 is controlled by the hydraulic pressure supplied from the SL solenoid valve (not shown) and the SLU solenoid valve (not shown) and the biasing force of the spring.

  When the SL solenoid valve is off and the SLU solenoid valve is on, the B2 control valve 4500 is in the state on the left side in FIG. In this case, the B2 brake 3620 is supplied with the hydraulic pressure adjusted from the D range pressure using the hydraulic pressure supplied from the SLU solenoid valve as a pilot pressure.

  When the SL solenoid valve is on and the SLU solenoid valve is off, the B2 control valve 4500 is in the state on the right side in FIG. In this case, the R range pressure is supplied to the B2 brake 3620.

  The function of ECT_ECU 8200 will be described with reference to FIG. Note that the functions of the ECT_ECU 8200 described below may be realized by hardware or may be realized by software.

  The ECT_ECU 8200 includes a shift determination unit 8400, a shift control unit 8402, a change rate detection unit 8410, and a learning control unit 8420.

  Shift determination unit 8400 determines whether or not to downshift from the fifth gear to the second gear or from the sixth gear to the third gear. Whether or not to downshift is determined, for example, according to a shift diagram having vehicle speed and accelerator opening as parameters.

  Shift control unit 8402 is moved down from the fifth gear that is formed by engaging B3 brake 3630 and C2 clutch 3650 to the second gear that is formed by engaging C1 clutch 3640 and B1 brake 3610. When shifting, control is performed so that the B3 brake 3630 is released and the engagement force of the C2 clutch 3650 is reduced to a predetermined target value before the C1 clutch 3640 and the B1 brake 3610 are engaged. Thereafter, the shift control unit 8402 controls the C2 clutch 3650 to be released and the C1 clutch 3640 and the B1 brake 3610 to be engaged.

  The shift control unit 8402 also has a third gear stage formed by engaging the C1 clutch 3640 and the B3 brake 3630 from a sixth gear stage formed by engaging the B1 brake 3610 and the C2 clutch 3650. When downshifting, the B1 brake 3610 is released before the C1 clutch 3640 and the B3 brake 3630 are engaged, and control is performed so that the engagement force of the C2 clutch 3650 decreases to a predetermined target value. Thereafter, the shift control unit 8402 controls the C2 clutch 3650 to be released and the C1 clutch 3640 and the B3 brake 3630 to be engaged.

  The engagement force is controlled by changing the engagement pressure of the friction engagement element, that is, the hydraulic pressure supplied to the friction engagement element. The engagement pressure of the C2 clutch 3650 is reduced so as to be the same pressure as a predetermined target engagement pressure. A method for setting the target engagement pressure will be described later.

  With reference to FIG. 6, the control mode of each friction engagement element when downshifting from the fifth gear to the second gear will be described.

  After starting the downshift at time T (A), the B3 brake 3630 is released. The engagement pressure of the C2 clutch 3650 is reduced to the target engagement pressure. When the engagement pressure of the C2 clutch 3650 is reduced to the target engagement pressure, the engagement force of the C2 clutch 3650 is reduced to the target value.

  At the time T (B) after the start of the downshift, the B1 brake 3610 is engaged. Thereafter, the C2 clutch 3650 is released while the C1 clutch 3640 is engaged. Note that after engaging the C1 clutch 3640, the C2 clutch 3650 may be released while the B1 brake 3610 is engaged.

  The downshift from the sixth gear to the third gear is performed in the same manner as the downshift from the fifth gear to the second gear. That is, the downshift from the sixth gear to the third gear is the same as the downshift from the fifth gear to the second gear except that the B1 brake 3610 and the B3 brake 3630 are switched. Done in a manner.

  The change rate detection unit 8410 is configured to detect the turbine rotational speed NT (input shaft rotational speed) detected by the input shaft rotational speed sensor 8022 after the downshift from the fifth gear to the second gear or from the sixth gear to the third gear is started. The actual change rate ΔNT of several NI) is detected.

  More specifically, after the engagement pressure of the C2 clutch 3650 is reduced to the target engagement pressure and the turbine rotational speed NT is increased to a threshold value or more, before the engagement of the C1 clutch 3640 is started. The rate of change ΔNT of the turbine rotational speed NT is detected.

  The learning control unit 8420 performs learning control of the target engagement pressure of the C2 clutch 3650, that is, the target value of the engagement force of the C2 clutch 3650. With the learning control, the target engagement pressure of the C2 clutch 3650, that is, the target value of the engagement force of the C2 clutch 3650 is being downshifted from the fifth gear to the second gear or from the sixth gear to the third gear. Correction is made according to the rate of change of the turbine speed NT.

  When the change rate ΔNT of the turbine rotational speed NT is smaller than a predetermined target change rate ΔNTT, the target engagement pressure is corrected so as to be reduced. When the change rate ΔNT of the turbine rotational speed NT is larger than the target change rate ΔNTT, the target engagement pressure of the C2 clutch 3650 is corrected so as to increase.

  More specifically, when the value (ΔNTT−ΔNT) obtained by subtracting the change rate ΔNT of the turbine rotational speed NT from the target change rate ΔNTT is larger than the first threshold value (the first threshold value is a positive value), It correct | amends so that a resultant pressure may become small. When the value obtained by subtracting the change rate ΔNT of the turbine speed NT from the target change rate ΔNTT is smaller than the second threshold value (the second threshold value is a negative value), the target engagement pressure of the C2 clutch 3650 is increased. It is corrected to.

  When the value obtained by subtracting the change rate ΔNT of the turbine speed NT from the target change rate ΔNTT is equal to or lower than the first threshold value and equal to or higher than the second threshold value, the target engagement pressure of the C2 clutch 3650 is maintained. .

  With reference to FIG. 7, a control structure of a program executed by ECT_ECU 8200 will be described. The program described below is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as S) 100, ECT_ECU 8200 determines whether or not to shift down from the fifth gear to the second gear or from the sixth gear to the third gear. When downshifting (YES in S100), the process proceeds to S102. If not (NO in S100), this process ends.

  At S102, ECT_ECU 8200 downshifts automatic transmission 2000 from the fifth gear to the second gear or from the sixth gear to the third gear.

  At S104, ECT_ECU 8200 determines that turbine speed NT (input shaft speed) detected by input shaft speed sensor 8022 during the downshift from the fifth gear to the second gear or from the sixth gear to the third gear. NI) change rate ΔNT is detected.

  In S110, ECT_ECU 8200 determines whether or not a value obtained by subtracting change rate ΔNT of turbine rotational speed NT from target change rate ΔNTT is greater than a first threshold value. If the value obtained by subtracting change rate ΔNT of turbine speed NT from target change rate ΔNTT is greater than the first threshold value (YES in S110), the process proceeds to S112. If not (NO in S110), the process proceeds to S120.

  In step S112, the ECT_ECU 8200 corrects the target engagement pressure of the C2 clutch 3650 to be reduced by a predetermined correction amount.

  In S120, ECT_ECU 8200 determines whether or not a value obtained by subtracting change rate ΔNT of turbine speed NT from target change rate ΔNTT is smaller than the second threshold value. If the value obtained by subtracting change rate ΔNT of turbine rotational speed NT from target change rate ΔNTT is smaller than the second threshold value (YES in S120), the process proceeds to S122. If not (NO in S120), the process proceeds to S130.

  In S122, ECT_ECU 8200 corrects the target engagement pressure of C2 clutch 3650 so as to increase by a predetermined correction amount.

  In S130, ECT_ECU 8200 maintains the target engagement pressure of C2 clutch 3650.

  An operation of the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  For example, if the accelerator opening is greatly increased by the driver's accelerator operation, it is determined that the gear shifts from the fifth gear to the second gear or from the sixth gear to the third gear (YES in S100). Therefore, automatic transmission 2000 is downshifted from the fifth gear to the second gear or from the sixth gear to the third gear (S102).

  In the following description, it is assumed that the downshift is performed from the sixth gear to the third gear. When the downshift is started, the B1 brake 3610 is released and the engagement pressure of the C2 clutch 3650 is reduced to the target engagement pressure.

  Thereby, one of the two friction engagement elements forming the gear stage before the shift can be released, and only the other can have an engagement force. By releasing one of the friction engagement elements, the shift can be started quickly.

  While the B1 brake 3610 is released and the engagement pressure of the C2 clutch 3650 is reduced to the target engagement pressure, the B3 brake 3630 is engaged. Thereafter, the C1 clutch 3640 is engaged and the C2 clutch 3650 is released.

  During the downshift, the rate of change ΔNT of the turbine rotational speed NT detected by the input shaft rotational speed sensor 8022 is detected (S104).

  If the value obtained by subtracting change rate ΔNT of turbine speed NT from target change rate ΔNTT is greater than the first threshold value (YES in S110), the rate of increase (increase rate) of turbine speed NT is insufficient. I can say that. In this case, the time required for the turbine rotation speed NT to increase to the synchronous rotation speed of the third gear is increased. Therefore, the time required for shifting can be increased.

  Therefore, the target engagement pressure of the C2 clutch 3650 is corrected so as to be reduced by a predetermined correction amount (S112). Thereby, the force (torque) acting on the input shaft of automatic transmission 2000 inside automatic transmission 2000 can be reduced. Therefore, it is possible to increase the rate of change of the turbine rotational speed NT during the downshift and increase the turbine rotational speed NT quickly. As a result, the time required for shifting can be prevented from becoming long.

  On the other hand, if the value obtained by subtracting change rate ΔNT of turbine speed NT from target change rate ΔNTT is smaller than the second threshold value (YES in S120), it can be said that the increasing speed of turbine speed NT is excessive. In this case, a large shock may occur when the B3 brake 3630 or the B1 brake 3610 is engaged.

  Therefore, the target engagement pressure of the C2 clutch 3650 is corrected so as to increase by a predetermined correction amount (S122). Thus, the force acting on the input shaft of automatic transmission 2000 can be increased inside automatic transmission 2000. Therefore, the change rate of the turbine speed NT during the downshift can be reduced. As a result, it is possible to reduce a shock that may occur at the time of shifting.

  When the value obtained by subtracting the change rate ΔNT of the turbine speed NT from the target change rate ΔNTT is equal to or less than the first threshold value and equal to or greater than the second threshold value (NO in S110, NO in S120), the turbine It can be said that the rotational speed NT is suitably controlled. Therefore, the target engagement pressure of the C2 clutch 3650 is maintained (S130). Thereby, it can control so that the difference of change rate (DELTA) NT of turbine rotation speed NT and target change rate (DELTA) NTT becomes small. Therefore, the input shaft rotational speed NI of the automatic transmission 2000 can be suitably controlled.

  As described above, according to the control device according to the present embodiment, when downshifting from the fifth gear to the second gear, the B3 brake is released and the engagement force of the C2 clutch decreases to the target value. Is done. Thereafter, the C2 clutch is released and the C1 clutch and the B1 brake are engaged. When downshifting from the sixth gear to the third gear, the B1 brake is released and the engagement force of the C2 clutch is reduced to the target value. Thereafter, the C2 clutch is released and the C1 clutch and the B3 brake are engaged. The target value of the engagement force of the C2 clutch is corrected according to the rate of change ΔNT of the turbine speed NT. As a result, when the change rate ΔNT of the turbine rotational speed NT is small, the target engagement pressure can be corrected to be small. Therefore, the force acting on the input shaft of the automatic transmission can be reduced inside the automatic transmission, and the turbine rotational speed NT can be quickly increased. When the change rate ΔNT of the turbine rotational speed NT is large, the target engagement pressure can be corrected so as to increase. Therefore, the force acting on the input shaft of the automatic transmission can be increased inside the automatic transmission. Therefore, the change rate of the turbine speed NT during the downshift can be reduced. As a result, the turbine rotational speed NT, that is, the input shaft rotational speed NI of the automatic transmission 2000 can be suitably controlled.

In the present embodiment, the fifth gear to the second gear or the sixth gear to the third gear.
Although the downshift to the high gear stage has been described, the combination of shifts is not limited to these.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram which shows the power train of a vehicle. It is a skeleton figure which shows the planetary gear unit of an automatic transmission. It is a figure which shows the operation | movement table | surface of an automatic transmission. It is a figure which shows the hydraulic circuit of an automatic transmission. It is a functional block diagram of ECT_ECU. It is a timing chart which shows the command oil pressure etc. of a friction engagement element. It is a flowchart which shows the control structure of the program which ECT_ECU performs.

Explanation of symbols

  1000 engine, 2000 automatic transmission, 3000 planetary gear unit, 3200 torque converter, 3212 rotating member, 3610 B1 brake, 3620 B2 brake, 3630 B3 brake, 3640 C1 clutch, 3650 C2 clutch, 4000 hydraulic circuit, 4210 SL1 linear solenoid, 4220 SL2 Linear solenoid, 4230 SL3 linear solenoid, 4240 SL4 linear solenoid, 8000 ECU, 8002 Air flow meter, 8004 Shift lever, 8006 Position switch, 8008 Accelerator pedal, 8010 Accelerator opening sensor, 8012 Brake pedal, 8014 Tread force sensor, 8016 Electronic throttle valve , 8018 Throttle opening Sensor, 8020 engine speed sensor, 8022 input shaft speed sensor, 8024 output shaft speed sensor, 8026 oil temperature sensor, 8100 engine ECU, 8200 ECT_ECU, 8300 ROM, 8400 shift judgment section, 8402 shift control section, 8410 change rate A detection unit, 8420 a learning control unit.

Claims (3)

A first gear stage is formed by engaging the first engaging element and the second engaging element, and the second gear is formed by engaging the second engaging element and the third engaging element. An automatic transmission control device in which a third gear stage is formed by engaging the third engagement element and the fourth engagement element.
Means for determining whether or not to perform a shift from the third gear to the first gear;
When it is determined that a shift from the third gear stage to the first gear stage is performed, the fourth engagement element is released, and the engagement force of the third engagement element is determined in advance. Control means for releasing the third engagement element and controlling the first engagement element and the second engagement element to engage with each other after being lowered to the target value.
Means for detecting the rate of change of the input shaft rotation speed after the engagement force of the third engagement element has decreased to the target value;
A control device for an automatic transmission, comprising: correction means for correcting the target value according to a change rate of the input shaft rotation speed.   2. The automatic transmission control according to claim 1, wherein the correction means includes means for correcting the target value so that the target value becomes larger when the change rate of the input shaft rotational speed is large than when the change rate is small. apparatus.   The correction means increases the target value when the change rate of the input shaft rotational speed is larger than a predetermined target change rate, and the change rate of the input shaft rotational speed is the predetermined target change rate. 2. The control device for an automatic transmission according to claim 1, further comprising means for correcting the target value so that the target value is reduced when the target value is smaller.

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