JP2008101697A - Control device and control method for power train, program for implementing the method and recording medium recorded the program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the slippage of a wheel by repeatedly increasing and decreasing transmitted power. <P>SOLUTION: In a control device for a power train, an ECU executes a program including a step of shifting a friction engagement element of an automatic transmission from an engaged state to a half-engaged state (S112) when determining that the wheel is slipped and a step of increasing an engagement force of the friction engagement element in the half-engaged state (S116) when a difference ΔN (2) between rotational frequencies of front and rear wheels after down-shift is below a threshold B (Yes in S114). After an increase in the engagement force, when the difference ΔN (2) between rotational frequencies of the front and rear wheels after down-shift exceeds the threshold B (No in S118), the friction engagement element is shifted from the engaged state to the half-engaged state again. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power train control device, a control method, a program for realizing the method, and a recording medium on which the program is recorded, and in particular, transmits power by a transmission mechanism capable of switching between a power transmission state and a cutoff state. The present invention relates to a technology for controlling a power train.

  Generally, a transmission is provided in a power train of a vehicle. The higher the gear ratio, the greater the effect of engine braking during braking of the vehicle. Therefore, when the vehicle is braked, the vehicle may be downshifted to increase the braking force. However, as the braking force increases, the wheel is more likely to slip. If the wheels slip, the posture of the vehicle becomes unstable. Therefore, a technique for suppressing slip due to gear shifting has been proposed.

  Japanese Patent Application Laid-Open No. 60-184753 (Patent Document 1) compares a rotational speed detector that detects the rotational speed of each of the front wheels and the rear wheels with the detected rotational speed and detects the occurrence of slip from the difference. A slip determination unit that outputs a slip detection signal, an automatic transmission in which the power transmission path is switched to a plurality of stages by the friction member, and a friction member that receives the slip detection signal and reduces the hydraulic pressure supplied to the friction member to change the speed A transmission control device for an automatic transmission for a vehicle including a line pressure adjusting unit that reduces the engagement speed of the vehicle is disclosed.

According to the speed change control device described in this publication, when the slip is detected from the rotation difference between the front and rear wheels and it is determined that the vehicle is traveling on a low μ road, the engagement speed of the friction member is reduced when the speed is changed. . As a result, the speed of change in torque transmitted to the tire that occurs during gear shifting can be reduced, and gear shifting that is gentle and less shocking can be performed. As a result, it is possible to effectively prevent the vehicle from spinning without promoting tire slip.
Japanese Patent Laid-Open No. 60-184753

  However, in the shift control device described in Japanese Patent Application Laid-Open No. 60-184753, the engagement speed is only reduced during a slip. Therefore, even if slip occurs, the braking force applied to the vehicle is unlikely to decrease. Therefore, there is a problem that the slip may not be reduced.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to control a power train capable of reducing wheel slip, a control method, a program for realizing the method, and a program therefor Is provided.

  A power train control device according to a first aspect of the present invention is a power train control device that has a power source and a transmission, and transmits power by a transmission mechanism that can switch between a power transmission state and a power transmission state. is there. The control device is configured to determine whether or not the wheel of the vehicle on which the power train is mounted is in a slipped state, and when it is determined that the wheel is in a slipped state when the transmission is downshifted, And means for controlling the transmission mechanism so that the power to be transmitted repeatedly increases and decreases. The power train control method according to the fourth invention has the same requirements as those of the power train control device according to the first invention.

  According to the first or fourth invention, it is determined whether or not the wheel of the vehicle on which the power train is mounted is in a slipped state. When it is determined that the wheels are slipping when the transmission is downshifted, the transmission mechanism is controlled so that the power to be transmitted repeatedly increases and decreases. Thereby, when the wheel slips, the braking force applied to the vehicle by the engine brake can be reduced. Therefore, it is possible to provide a power train control device or control method capable of reducing wheel slip.

  In the power train control device according to the second invention, in addition to the configuration of the first invention, the transmission mechanism is a friction engagement element provided in the transmission. The power train control method according to the fifth invention has the same requirements as the power train control device according to the second invention.

  According to the second or fifth invention, the transmission mechanism is a friction engagement element provided inside the transmission. Thus, when the wheel slips, the wheel slip can be reduced by controlling the power transmitted by the friction engagement element provided inside the transmission to increase and decrease repeatedly.

  In the power train control device according to the third aspect of the invention, the transmission mechanism is provided between the power source and the transmission in addition to the configuration of the first aspect of the invention. The power train control method according to the sixth invention has the same requirements as those of the power train control device according to the third invention.

  According to the third or sixth invention, the transmission mechanism is provided between the power source and the transmission. Thereby, when the wheel slips, the power transmitted by the transmission mechanism provided between the power source and the transmission is controlled so as to increase and decrease repeatedly, so that the wheel slip can be reduced.

  A program according to a seventh aspect is a program for causing a computer to realize the power train control method according to any of the fourth to sixth aspects, wherein the recording medium according to the eighth aspect is the fourth to sixth aspect. A computer-readable recording medium recording a program for causing a computer to implement the power train control method according to any of the inventions.

  According to the seventh or eighth invention, the control method according to any of the fourth to sixth inventions can be realized using a computer (which may be general purpose or dedicated).

  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.

<First Embodiment>
A vehicle equipped with a control device according to a first 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 wheels 7001 and 7002, rear wheels 7003 and 7004, and an ECU (Electronic Control Unit) 8000 are included. The control device according to the present embodiment is realized, for example, by executing a program recorded in a ROM (Read Only Memory) 8002.

  The power train in the present embodiment includes engine 1000, automatic transmission 2000, differential gear 5000, and drive shaft 6000.

  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.

  Automatic transmission 2000 is connected to engine 1000 via torque converter 3200. Automatic transmission 2000 changes the rotational speed of the crankshaft to a desired rotational speed by forming a desired gear stage. Instead of the automatic transmission that forms the gear stage, CVT (Continuously Variable Transmission) that changes the gear ratio steplessly may be mounted. Furthermore, you may make it mount the transmission which consists of a constant-meshing-type gearwheel speed-changed by an actuator.

  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 7001, 7002 via the drive shaft 6000.

  The ECU 8000 includes a position switch 8006 for the shift lever 8004, an accelerator opening sensor 8010 for the accelerator pedal 8008, a stroke sensor 8014 for the brake pedal 8012, a throttle opening sensor 8018 for the electronic throttle valve 8016, and an engine speed sensor 8020. The input shaft rotational speed sensor 8022, the output shaft rotational speed sensor 8024, and the oil temperature sensor 8026 are connected via a harness or the like. Further, wheel speed sensors 8031 to 8034 are connected to the ECU 8000 via a harness or the like.

  The position of shift lever 8004 is detected by position switch 8006, and a signal indicating 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, in the present embodiment, a manual shift mode in which the driver can select an arbitrary gear stage can 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. Stroke sensor 8014 detects the stroke amount of brake pedal 8012 and transmits a signal representing the detection result to 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).

  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 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. ECU 8000 detects the vehicle speed using 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.

  One wheel speed sensor 8031 to 8034 is provided for each wheel. Wheel speed sensors 8031 to 8034 detect the rotational speeds of front wheels 7001 and 7002 and rear wheels 7003 and 7004 and transmit signals representing the detection results to ECU 8000.

  ECU 8000 includes position switch 8006, accelerator opening sensor 8010, stroke sensor 8014, throttle opening sensor 8018, engine speed sensor 8020, input shaft speed sensor 8022, output shaft speed sensor 8024, oil temperature sensor 8026, wheel speed. Based on the signals sent from the sensors 8031 to 8034 and the like and the map and program stored in the ROM 8002, the devices are controlled so that the vehicle is in a desired running 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.

  Further, the ECU 8000 operates the shift lever 8004 to downshift or upshift, or change the shift range. In addition to the shift lever 8004, a downshift or an upshift may be performed by operating a switch provided on the steering or the steering column, or the shift range may be changed.

  The automatic transmission 2000 can transmit the driving force to the front wheels 7001 and 7002 by forming any one of the first to sixth gears. The number of gear stages is not limited to “6”.

  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.

  B1 brake 3610, B2 brake 3620, and B3 brake 3630, and C1 clutch 3640 and C2 clutch 3650 are operated by hydraulic pressure. These friction engagement elements can be switched between a state where power is transmitted and a state where power is interrupted.

  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 valve (hereinafter referred to as SL (1)) 4210, an SL2 linear solenoid valve ( SL220 (hereinafter referred to as SL (2)) 4220, SL3 linear solenoid valve (hereinafter referred to as SL (3)) 4230, SL4 linear solenoid valve (hereinafter referred to as SL (4)) 4240, and SLT A linear solenoid valve (hereinafter referred to as SLT) 4300 and a B2 control valve 4400 are included.

  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 generates a modulator pressure lower than the line pressure using the line pressure as a source pressure. Solenoid modulator valve 4200 generates a modulator pressure by the hydraulic pressure introduced to feedback port 4202 and the biasing force of the spring.

  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 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 ECU 8000.

  The B2 control valve 4400 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 4400. The B2 control valve 4400 is controlled by the hydraulic pressure supplied from the SL solenoid valve 4700 and the SLU solenoid valve 4800 and the biasing force of the spring.

  When the SL solenoid valve 4700 is off and the SLU solenoid valve 4800 is on, the B2 control valve 4400 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 4800 as a pilot pressure.

  When the SL solenoid valve 4700 is on and the SLU solenoid valve 4800 is off, the B2 control valve 4400 is in the state on the right side in FIG. In this case, the R range pressure is supplied to the B2 brake 3620.

  With reference to FIG. 5, the configuration for supplying hydraulic pressure to torque converter 3200 in torque converter 3200 and hydraulic circuit 4000 will be described.

  The torque converter 3200 includes a lockup clutch 3220 that directly connects the input shaft 3100 and the output shaft 3210, a pump impeller 3230 on the input shaft side, a turbine runner 3240 on the output shaft side, and a stator 3250 that exhibits a torque amplification function. And a one-way clutch 3260.

  The torque converter 3200 is supplied with one of the secondary pressure regulated by the secondary regulator valve 4020 and the modulator pressure regulated by the solenoid modulator valve 4200.

  The secondary regulator valve 4020 regulates excess hydraulic pressure (secondary pressure) discharged when the primary regulator valve 4006 regulates the line pressure.

  The secondary pressure regulated by the secondary regulator valve 4020 is supplied to the lockup relay valve 4500. The lockup relay valve 4500 is supplied with a modulator pressure from a solenoid modulator valve 4200 in addition to the secondary regulator valve 4020.

  Secondary pressure is introduced into the input port (1) 4510 of the lockup relay valve 4500. Modulator pressure is introduced into the input port (2) 4520 and the input port (3) 4530 of the lockup relay valve 4500.

  The spool of the lockup relay valve 4500 slides according to the hydraulic pressure supplied from the SL solenoid valve 4700 and the biasing force of the spring. When the SL solenoid valve 4700 is off, the lockup relay valve 4500 is off (left side state). When the SL solenoid valve 4700 is on, the lockup relay valve 4500 is on (right state).

  The ECU 8000 determines whether the SL solenoid valve 4700 is turned on or off. That is, whether the lock-up relay valve 4500 is turned on or turned off is controlled by the ECU 8000 via the SL solenoid valve 4700.

  When the lockup relay valve 4500 is in the off state (the left side state), the secondary pressure is released between the release side oil chamber (the lockup clutch 3220 and the converter cover 3270) of the torque converter 3200 via the lockup relay valve 4500. Space). The hydraulic pressure of the torque converter 3200 engagement side oil chamber (pump impeller 3230 side) is supplied to the oil cooler 3700 via the lockup relay valve 4500. Therefore, lockup clutch 3220 is pulled away from converter cover 3270, and lockup clutch 3220 is released. At this time, the modulator pressure is blocked by the lockup relay valve 4500. When the lock-up clutch 3220 is in the released state, the power is cut off.

  When the lock-up relay valve 4500 is in the ON state (right-side state), the modulator pressure introduced into the input port (2) 4520 of the lock-up relay valve 4500 passes through the lock-up relay valve 4500 to the torque converter 3200. It is supplied to the engagement side oil chamber. Hydraulic pressure is drained from the release side oil chamber of the torque converter 3200 through the lockup relay valve 4500 and the lockup control valve 4600. Therefore, lockup clutch 3220 is pressed against converter cover 3270 side, and lockup clutch 3220 is engaged. At this time, the secondary pressure is blocked by the lockup relay valve 4500. When the lock-up clutch 3220 is in the engaged state, the power is transmitted.

  The hydraulic pressure drained from the release side oil chamber of the torque converter 3200 is introduced into the input port 4610 of the lockup control valve 4600 via the lockup relay valve 4500. The hydraulic pressure introduced from the input port 4610 is drained from the drain port 4620.

  The amount of oil drained from the drain port 4620 of the lockup control valve 4600 varies depending on the hydraulic pressure supplied from the SLU solenoid valve 4800 to the lockup control valve 4600. That is, the engagement force of the lockup clutch 3220 (the differential pressure between the engagement side oil chamber and the release side oil chamber) is controlled by the hydraulic pressure output from the SLU solenoid valve 4800.

  The ECU 8000 will be further described with reference to FIG. The functions of ECU 8000 described below may be realized by hardware or may be realized by software.

  ECU 8000 includes a transmission unit 8110, a slip determination unit 8120, and a pumping control unit 8130. When manual shift mode is selected, transmission unit 8110 controls automatic transmission 2000 to perform a downshift or an upshift according to the operation of shift lever 8004 by the driver.

  The slip determination unit 8120 determines whether or not the wheel has slipped at the time of the downshift, more specifically, immediately after the downshift, based on the difference in rotational speed between the front and rear wheels. For example, the difference in rotational speed between the front and rear wheels before downshifting (the rotational speed of the rear wheel (driven wheel) −the rotational speed of the front wheel (driving wheel)) ΔN (1) and the rotational speed difference ΔN between the front and rear wheels after downshifting. If the difference from (2) is greater than or equal to threshold A, it is determined that the wheel has slipped.

  The threshold A is determined by a map using, for example, vehicle speed, gear speed, steering angle, etc. as parameters. Note that it may be determined that the wheel has slipped from the difference between the rotational speeds of the front wheels 7001 and 7002, that is, the left and right wheels before the downshift in the drive wheels, and the rotational speed difference between the left and right wheels after the downshift.

  The pumping control unit 8130 controls the friction engagement element (clutch or brake) of the automatic transmission 2000 to repeatedly engage and disengage (half-engage) when it is determined that the wheel has slipped during the downshift.

  With reference to FIG. 7, a control structure of a program executed by ECU 8000 serving as the control device according to the present embodiment will be described. Note that the program described below is repeatedly executed at a predetermined cycle.

  In step (hereinafter step is abbreviated as S) 100, ECU 8000 determines whether or not shift lever 8004 has been operated so as to perform a downshift in the manual shift mode. If shift lever 8004 is operated so as to perform a downshift in the manual shift mode (YES in S100), the process proceeds to S102. Otherwise (NO in S100), this process ends.

  In S102, ECU 8000 determines whether or not the current vehicle speed is a vehicle speed at which downshift is permitted. For example, if the current vehicle speed is lower than the vehicle speed set as a threshold value for permitting downshift, it is determined that the vehicle speed is permitted for downshift. If the current vehicle speed is a vehicle speed at which downshift is permitted (YES in S102), the process proceeds to S104. Otherwise (NO in S102), this process ends. In S104, ECU 8000 downshifts.

  In S106, ECU 8000 determines whether or not front-rear wheel rotation speed difference ΔN (2) after the downshift is higher than threshold value A by a threshold value A or higher than front-rear wheel rotation speed difference ΔN (1) before the downshift. If rotational speed difference ΔN (2) between the front and rear wheels after the downshift is higher than threshold value A by more than threshold value A (YES at S106), the process proceeds to S108. . If not (NO in S106), this process ends. In S108, ECU 8000 determines that the wheel has slipped.

  In S110, ECU 8000 determines whether or not the throttle opening is in a fully closed state. If the throttle opening is in a fully closed state (YES in S110), the process proceeds to S112. Otherwise (NO in S110), this process ends. Note that the throttle opening being fully closed means that the throttle valve 8016 is opened by an opening required for idling.

  In S112, ECU 8000 changes the friction engagement element of automatic transmission 2000 from the engaged state to the semi-engaged state. For example, C1 clutch 3640 or C2 clutch 3650, which is an input clutch of automatic transmission 2000, is changed from the engaged state to the half-engaged state. In addition, the friction engagement element made into a semi-engagement state from an engagement state is not restricted to these.

  In S114, ECU 8000 determines whether or not rotation speed difference ΔN (2) between the front and rear wheels after the downshift is equal to or smaller than threshold value B. If the rotational speed difference ΔN (2) between the front and rear wheels after the downshift is equal to or smaller than threshold value B (YES in S114), the process proceeds to S116. If not (NO in S114), the process proceeds to S112. The threshold value B is determined by a map using, for example, vehicle speed, gear speed, steering angle, etc. as parameters.

  In S116, ECU 8000 increases the engagement force of the friction engagement element brought into the half-engagement state. For example, the engagement force is increased until the friction engagement element is engaged.

  In S118, ECU 8000 determines whether or not rotation speed difference ΔN (2) between the front and rear wheels after the downshift is equal to or smaller than threshold value B. If the rotational speed difference ΔN (2) between the front and rear wheels after the downshift is equal to or smaller than threshold value B (YES in S118), this process ends. If not (NO in S118), the process proceeds to S112.

  The operation of ECU 8000 serving as the control device according to the present embodiment based on the structure and flowchart as described above will be described.

  If shift lever 8004 is operated so as to perform a downshift in the manual shift mode (YES in S100) and the current vehicle speed is a vehicle speed permitting the downshift (YES in S102), the downshift is performed (S104). ).

  When a large engine brake acts on the vehicle due to the downshift, the rotational speeds of the front wheels 7001 and 7002 that are drive wheels are reduced. At this time, when the front wheels 7001 and 7002 slip, the rotational speeds of the rear wheels 7003 and 7004 that are driven wheels become higher than the rotational speeds of the front wheels 7001 and 7002 that are driving wheels.

  Therefore, if the speed difference ΔN (2) between the front and rear wheels after the downshift is higher than the threshold value AN (1) before and after the downshift by a threshold value A (YES in S106), the wheel slips. Is determined (S108).

  In this case, if the throttle opening is in the fully closed state (YES in S110), the friction engagement element of automatic transmission 2000 is changed from the engaged state to the semi-engaged state (S112).

  Thereafter, when the difference in rotational speed ΔN (2) between the front and rear wheels after the downshift is equal to or smaller than threshold value B (YES in S114), the engagement force of the friction engagement element is increased (S116). When the difference in rotational speed ΔN (2) between the front and rear wheels after the downshift is greater than the threshold value B after the engagement force is increased (S118), the friction engagement element of automatic transmission 2000 is changed from the engaged state to the half-engaged state again. (S112).

  Even after the engagement force of the frictional engagement element is increased, the frictional engagement element is brought into a semi-engaged state or engaged until the rotational speed difference ΔN (2) between the front and rear wheels after the downshift becomes equal to or less than the threshold value B. And so on. That is, increase / decrease in the power transmitted by the friction engagement element is repeated. Thereby, the braking force by an engine brake can be made small. Therefore, the slip of the front wheels 7001 and 7002 which are drive wheels can be reduced.

  As described above, according to the ECU that is the control device according to the present embodiment, when it is determined that the wheel slips during the downshift, the friction engagement element of the automatic transmission is brought into a semi-engagement state or an engagement state. Or repeatedly. That is, increase / decrease in the power transmitted by the friction engagement element is repeated. Thereby, the braking force by an engine brake can be made small. Therefore, the slip of the front wheel which is a driving wheel can be reduced.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment described above in that the lock-up clutch is placed in a semi-engaged state or engaged state instead of the friction engagement element of the automatic transmission. Other structures are the same as those in the first embodiment. Their functions are the same. Therefore, description thereof will not be repeated here.

  With reference to FIG. 8, the function of ECU 8000 serving as the control device according to the present embodiment will be described. The functions of ECU 8000 described below may be realized by hardware or may be realized by software. The same components as those in the first embodiment are denoted by the same reference numerals. Therefore, detailed description thereof will not be repeated here.

  In this embodiment, pumping control unit 8132 of ECU 8000 performs control so that lockup clutch 3220 repeats engagement and disengagement (half-engagement) when it is determined that the wheel slips during downshift.

  With reference to FIG. 9, a control structure of a program executed by ECU 8000 which is the control apparatus according to the present embodiment will be described. Note that the program described below is repeatedly executed at a predetermined cycle. The same step numbers are assigned to the same processes as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  In S200, ECU 8000 determines whether or not lockup clutch 3220 is engaged. If lock-up clutch 3220 is engaged (YES in S200), the process proceeds to S202. Otherwise (NO in S200), this process ends.

  In S202, ECU 8000 changes lockup clutch 3220 from the engaged state to the semi-engaged state. In S204, ECU 8000 increases the engagement force of lockup clutch 3220 in the half-engaged state. For example, the engagement force is increased until the lockup clutch 3220 is engaged.

  Even if it does in this way, the effect similar to the above-mentioned 1st Embodiment can be acquired. When an automatic transmission composed of a constantly meshing gear that is shifted by an actuator is mounted, the dry single-plate clutch may be put into a semi-engaged state or engaged state instead of the lock-up clutch 3220. You may make it repeat.

  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. FIG. 3 is a first diagram illustrating a hydraulic circuit of an automatic transmission. FIG. 3 is a second diagram illustrating a hydraulic circuit of an automatic transmission. It is a functional block diagram of ECU which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the control structure of the program which ECU which concerns on the 1st Embodiment of this invention performs. It is a functional block diagram of ECU which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the control structure of the program which ECU which concerns on the 1st Embodiment of this invention performs.

Explanation of symbols

  1000 Engine, 2000 Automatic transmission, 3000 Planetary gear unit, 3200 Torque converter, 3220 Lock-up clutch, 3610 B1 brake, 3620 B2 brake, 3630 B3 brake, 3640 C1 clutch, 3650 C2 clutch, 4000 Hydraulic circuit, 7001, 7002 Front wheel, 7003 , 7004 Rear wheel, 8000 ECU, 8002 ROM, 8004 Shift lever, 8006 Position switch, 8031, 8032, 8033, 8034 Wheel speed sensor, 8110 Transmission unit, 8120 Slip judgment unit, 8130, 8132 Pumping control unit.

Claims (8)

A power train control device having a power source and a transmission and transmitting power by a transmission mechanism capable of switching between a state of transmitting power and a state of blocking power,
Means for determining whether or not a wheel of a vehicle on which the power train is mounted is in a slipped state;
And a means for controlling the transmission mechanism so that the power transmitted is repeatedly increased or decreased when it is determined that the wheel slips during downshifting of the transmission.   The power train control device according to claim 1, wherein the transmission mechanism is a friction engagement element provided inside the transmission.   The power train control device according to claim 1, wherein the transmission mechanism is provided between the power source and the transmission. A method for controlling a power train having a power source and a transmission and transmitting power by a transmission mechanism capable of switching between a state of transmitting power and a state of blocking power,
Determining whether a wheel of a vehicle on which the power train is mounted is in a slipped state;
And controlling the transmission mechanism so that the transmitted power repeatedly increases and decreases when it is determined that the wheels are slipping during the downshift of the transmission.   The power train control method according to claim 4, wherein the transmission mechanism is a friction engagement element provided inside the transmission.   The power train control method according to claim 4, wherein the transmission mechanism is provided between the power source and the transmission.   The program which makes a computer implement | achieve the control method in any one of Claims 4-6.   A computer-readable recording medium recording a program for causing a computer to implement the control method according to claim 4.

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