JP2009190436A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress shock in re-acceleration during carrying out down shift gear change in a control device of a vehicle which includes an engine, motor and automatic transmission and outputs driving force from the motor to driving wheel through the automatic transmission. <P>SOLUTION: During carrying out down shift gear change, the control device predicts whether the engine becomes high rotation and torque down of the motor (a second motor generator MG 2) cannot be carried out. When the torque down cannot be carried out, pressure up of engaging oil pressure is made faster than the normal control time by making a gain Ga of the engaging oil pressure of a frictional engagement factor at an engagement side of the automatic transmission (brake B2) is made higher than the normal control time. Speed-change time i.e., time to engagement completion of frictional engagement factor can be shortened by such engaging oil pressure control, and rotation raise (motor blowing) of the motor can be suppressed. As the result, engaging shock can be reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle control apparatus that includes an engine and an electric motor that output driving force for traveling, and that outputs power from the electric motor to driving wheels via a transmission.

  In recent years, from the viewpoint of environmental protection, it has been desired to reduce exhaust gas emissions from engines (internal combustion engines) mounted on vehicles and to improve fuel consumption rate (fuel consumption). Hybrid vehicles equipped with are put into practical use.

  The hybrid vehicle includes an engine such as a gasoline engine or a diesel engine, and an electric motor (for example, a motor generator or a motor) that is driven by power generation by the engine output or battery power to assist engine output. Either one or both of them is used as a driving source.

  In the hybrid vehicle, the operating range (specifically, driving or stopping) of the engine and the electric motor is controlled based on the vehicle speed and the accelerator opening. For example, in a region where the engine efficiency is low, such as when starting or running at a low speed, the engine is stopped and the drive wheels are driven by the power of only the electric motor. Further, during normal traveling, control is performed such that the engine is driven and the driving wheels are driven by the power of the engine. Further, at the time of high load such as full-open acceleration, in addition to engine power, control is performed such that power is supplied from the battery to the electric motor and the power from the electric motor is added as auxiliary power.

  As one of such hybrid vehicle drive devices, for example, a mechanism using a sun gear, a ring gear, and a carrier (pinion gear) as rotating elements, the output of the engine is supplied to a first electric motor (hereinafter also referred to as a generator) and a transmission shaft (ring gear). A power distribution mechanism that distributes the output to the shaft) (or combines the output of the engine and the output of the first electric motor to output to the transmission shaft), the second electric motor, the second electric motor (hereinafter also referred to as a motor), and the drive wheels. A power storage device (battery) capable of charging the generated power from the first and second motors and supplying the power to the first and second motors, and a stepped automatic transmission provided between the first and second motors. And a vehicle drive device that outputs power from a second electric motor to drive wheels (output shaft) via an automatic transmission (see, for example, Patent Document 1).

  In such a vehicle drive device, the power distribution mechanism functions as a differential mechanism, and the main part of the power from the engine is mechanically transmitted to the drive wheels by the differential action, and the remaining part of the power from the engine is transferred. By electrically transmitting using the electric path from the 1st electric motor to the 2nd electric motor, it functions as a transmission in which a gear ratio is changed electrically. As a result, the vehicle can be run while maintaining the engine in an optimum operating state, and fuel consumption can be improved. Further, in this type of hybrid vehicle drive device, the power balance is normally controlled to be zero when the generator power generation amount, the battery charge / discharge amount, and the motor consumption amount are all added.

  On the other hand, a planetary gear type transmission that sets a gear stage (shift stage) using a clutch or brake that is a friction engagement element and a planetary gear unit is applied as a transmission mounted on a hybrid vehicle. For example, there are two brakes as friction engagement elements, a gear position that engages one brake and releases the other brake (for example, a low speed gear), and a gear that engages the other brake and releases one brake. Switching to a stage (for example, a high-speed stage) is performed. In this case, a so-called clutch-to-clutch shift is performed in which the engagement of the frictional engagement element on the engagement side and the release of the frictional engagement element on the release side are simultaneously performed during the shift.

  A vehicle such as a hybrid vehicle is provided with a shift operation device operated by a driver. By operating a shift lever of the shift operation device, the shift position of the automatic transmission is set to, for example, P (parking). The position, R (reverse) position, N (neutral) position, D (drive) position, and the like can be switched. Further, in recent years, a shift operation device with a sequential mode has been put into practical use. In sequential mode, a sequential shift range of multiple stages (for example, 6 stages) is set, and when the shift lever is placed at the S (sequential) position and an upshift (+) or downshift (-) operation is performed, The sequential shift range is increased or decreased. When such a sequential mode is selected, the engine speed is controlled to be higher than when traveling in the D range.

As a technique related to control during shifting of the hybrid vehicle, Patent Document 2 below discloses that the engine and the first electric motor are changed so that the engine speed changes at a smaller change speed than during normal shifting during the shifting of the automatic transmission. A technique for controlling the MG1, the second electric motor MG2, the friction engagement device, and the like is disclosed.
JP 2006-316848 A JP 2007-237923 A

  By the way, in the hybrid vehicle described above, when the accelerator pedal is depressed during the downshift, the gear shift is performed to reduce the shift shock and the friction material thermal load of the friction engagement element (brake) of the automatic transmission. While it is necessary to reduce the torque of the motor (second electric motor), the protection control is activated and the torque cannot be reduced when the engine becomes high. In other words, if the engine speed increases during gear shifting, the engine speed is controlled by the generator (first motor) responsible for the reaction force of the engine torque in order to prevent engine overspeed (part protection), so the amount of power generation increases. To do. When the amount of power generation increases in this way, power consumption by the motor (second electric motor) is required, so that a desired torque reduction cannot be performed.

  For this reason, if torque reduction cannot be performed during gear shifting, it is impossible to limit the blowing of the motor that is the gear to be shifted, so the motor rotation speed and the target rotation speed (synchronous rotation speed of the target gear stage) The friction engagement element is engaged with a differential rotation between them, and an engagement shock may occur.

  In hybrid vehicles, various technologies for canceling changes in driving force during gear shifting by cooperative control between a motor and an engine (generator) have been disclosed. There is a case where the cooperative control cannot be performed, and there is a concern that a shift shock may occur or the friction material heat load may increase.

  The present invention has been made in consideration of such circumstances, and an engine and an electric motor that output driving force for traveling, and a plurality of gear stages by engaging or releasing a friction engagement element in a predetermined state. In a vehicle control apparatus that includes an automatic transmission to be set and outputs power from an electric motor to drive wheels via the automatic transmission, a control capable of suppressing a shock during re-acceleration during a downshift. The purpose is realization.

  The present invention relates to an engine and an electric motor that output driving force for traveling, a power storage device that can charge electric power generated from the electric motor and supply electric power to the electric motor, and a friction engagement element engaged in a predetermined state. An automatic transmission that sets a plurality of gear stages by releasing, and presupposes a vehicle control device that outputs power from the electric motor to drive wheels (output shaft) via the automatic transmission. In such a vehicle control device, a determination means for determining whether or not torque reduction of the motor cannot be performed during downshift, and engagement of the automatic transmission when torque reduction of the motor cannot be performed. And an engagement pressure increasing means for increasing the engagement pressure of the friction engagement element on the side faster than that during normal control.

  According to the present invention, when it is predicted that the torque of the electric motor (motor) cannot be reduced due to the protection control function during the downshift, the engine on the engagement side of the automatic transmission is Since the increase in the engagement pressure of the friction engagement element is set faster than that during normal control, the shift time, that is, the time until the engagement of the friction engagement element is completed can be shortened. Can be suppressed. Thus, even if the torque of the motor cannot be reduced, the motor rotation speed (motor rotation speed) between the engagement of the friction engagement elements and the engagement target rotation speed (synchronous rotation speed of the target gear stage) can be reduced. The differential rotation can be reduced, and the engagement shock can be reduced.

  Next, a specific configuration of the present invention will be described.

  First, in the present invention, when the engine speed is equal to or higher than the determination threshold, it is determined that the motor torque cannot be reduced, and the engagement pressure of the friction engagement element on the engagement side of the automatic transmission is increased. Is executed to make the control faster than during normal control (hereinafter also referred to as engagement pressure increase control).

  In this case, the determination threshold value set for the engine speed is the limit speed of the engine itself, the upper limit speed of the generator (MG1), the upper limit speed of the rotating body of the driving force transmission system (pinion gear, etc.), etc. The allowable engine speed determined on the basis of this is taken into consideration, and a value that allows for a margin with respect to the engine allowable engine speed (determination threshold = allowable engine speed−allowance) may be used.

  The determination threshold value set for the engine speed may be set variably in consideration of the power acceptance state of the power storage device (battery). Explaining this point, when the power storage device is in a state where power can be received, the engine speed is higher than in the case where power cannot be received, and therefore the determination threshold can be set higher. In view of this point, by setting the determination threshold variable, it is possible to minimize the region to which the above-described engagement pressure increase control is applied. Note that the determination threshold value may be variably set in consideration of the vehicle speed, or the determination threshold value may be variably set in consideration of both the power reception state of the power storage device and the vehicle speed.

  In the present invention, as a method of increasing the engagement pressure of the friction engagement element of the automatic transmission, a method of setting the control gain of the engagement hydraulic pressure of the friction engagement element higher than the gain during normal control, the friction engagement A method of setting the engagement hydraulic pressure higher by adding a predetermined hydraulic pressure to the engagement hydraulic pressure at the time of normal control of the combined element, or a timing at which the engagement hydraulic pressure of the friction engagement element is started to be higher than that at the time of normal control. The method of setting can be mentioned. Each of these methods may be performed alone, or any two methods or all methods may be combined.

  In the present invention, the control for increasing the engagement pressure of the friction engagement element is a control performed when the torque of the motor cannot be reduced, and is a special control different from the normal control. During the execution of the engagement pressure increase control, the engagement pressure learning of the friction engagement element (for example, the engagement pressure learning for stabilizing the downshift operation) is prohibited, and the adverse effect on the normal control due to the erroneous learning is prohibited. Is preferably excluded.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an example of a hybrid vehicle to which the present invention is applied.

  The hybrid vehicle HV in this example includes an engine 1, a first motor generator MG 1, a second motor generator MG 2, a power distribution mechanism 2, an automatic transmission 3, an inverter 4, a battery (HV battery) 5, a differential gear 6, and drive wheels 7. , A hydraulic control circuit 300 (see FIG. 4), a shift operation device 8 (see FIG. 5), an ECU (Electronic Control Unit) 100, and the like.

  The engine 1, the motor generators MG1 and MG2, the automatic transmission 3, the power distribution mechanism 2, the automatic transmission 3 (including the hydraulic control circuit 300), the shift operation device 8, and each part of the ECU 100 will be described below.

-Engine-
The engine 1 is a known power device that outputs power by burning fuel such as a gasoline engine or a diesel engine, and can control the operation state such as throttle opening (intake amount), fuel injection amount, and ignition timing. It is configured. The rotation speed (engine rotation speed) of the crankshaft 11 that is the output shaft of the engine 1 is detected by the engine rotation speed sensor 201. The engine 1 is driven and controlled by the ECU 100.

-Motor generator-
Motor generators MG1 and MG2 are AC synchronous motors that function as electric motors as well as electric generators. Motor generators MG 1 and MG 2 are connected to battery 5 through inverter 4. Inverter 4 is controlled by ECU 100, and regeneration or power running (assist) of motor generators MG 1 and MG 2 is set by the control of inverter 4. The regenerative power at that time is charged into the battery 5 via the inverter 4. Driving power for motor generators MG1 and MG2 is supplied from battery 5 via inverter 4.

-Power distribution mechanism-
The power distribution mechanism 2 includes an external gear sun gear S21, an internal gear ring gear R21 arranged concentrically with the sun gear S21, a plurality of pinion gears P21 that mesh with the sun gear S21 and mesh with the ring gear R21, and the plurality of pinion gears P21. And a carrier CA21 that holds the pinion gear P21 in a rotatable and revolving manner, and a planetary gear mechanism that performs a differential action using the sun gear S21, the ring gear R21, and the carrier CA21 as rotational elements.

  The crankshaft 11 of the engine 1 is connected to the carrier CA21 of the power distribution mechanism 2. In addition, the rotation shaft of the first motor generator MG1 is connected to the sun gear S21 of the power distribution mechanism 2. A ring gear shaft 21 is connected to the ring gear R21 of the power distribution mechanism 2. The ring gear shaft 21 is connected to the drive wheel 7 via the differential gear 6. Further, the rotary shaft of the second motor generator MG <b> 2 is connected to the ring gear shaft 21 via the automatic transmission 3.

  In the power distribution mechanism 2 having such a structure, when the first motor generator MG1 functions as a generator, the power from the engine 1 input from the carrier CA21 is applied to the sun gear S21 side and the ring gear R21 side according to the gear ratio. Distribute. On the other hand, when first motor generator MG1 functions as an electric motor, the power from engine 1 input from carrier CA21 and the power from first motor generator MG1 input from sun gear S21 are integrated and output to ring gear R21. .

-Automatic transmission-
As shown in FIG. 2, the automatic transmission 3 is a planetary gear type equipped with a double pinion type first planetary gear mechanism 31, a single pinion type second planetary gear mechanism 32, two brakes B1, B2, and the like. The input shaft 30 is coupled to the rotation shaft of the second motor generator MG2. The output shaft 33 of the automatic transmission 3 is connected to the ring gear shaft 21 (FIG. 1).

  The first planetary gear mechanism 31 includes an external gear sun gear S31, an internal gear ring gear R31 disposed concentrically with the sun gear S31, a plurality of first pinion gears P31a meshing with the sun gear S31, and the first pinion gear. A plurality of second pinion gears P31b that mesh with P31a and mesh with ring gear R31, and a carrier CA31 that holds the plurality of first pinion gears P31a and the plurality of second pinion gears P31b so as to rotate and revolve freely. The carrier CA31 of the first planetary gear mechanism 31 is integrally connected to the carrier CA32 of the second planetary gear mechanism 32. The sun gear S31 of the first planetary gear mechanism 31 is selectively connected to the housing 3A, which is a non-rotating member, via the brake B1, and the rotation of the sun gear S31 is prevented by the engagement of the brake B1.

  The second planetary gear mechanism 32 includes an external gear sun gear S32, an internal gear ring gear R32 arranged concentrically with the sun gear S32, a plurality of pinion gears P32 meshing with the sun gear S32 and meshing with the ring gear R32. And a carrier CA32 that holds the plurality of pinion gears P32 so as to rotate and revolve freely. The sun gear S32 of the second planetary gear mechanism 32 is connected to the input shaft 30, and the carrier CA32 is connected to the output shaft 33. Further, the ring gear R32 of the second planetary gear mechanism 32 is selectively coupled to the housing 3A via the brake B2, and the rotation of the ring gear R32 is prevented by the engagement of the brake B2.

  The rotational speed of the input shaft 30 of the automatic transmission 3 (input shaft rotational speed) is detected by the input shaft rotational speed sensor 203. Further, the rotational speed (output shaft rotational speed) of the output shaft 33 of the automatic transmission 3 is detected by the output shaft rotational speed sensor 204. Based on the rotation speed ratio (output shaft rotation speed / input shaft rotation speed) obtained from the output signals of the input shaft rotation speed sensor 203 and the output shaft rotation speed sensor 204, the current gear stage of the automatic transmission 3 is determined. be able to.

  The automatic transmission 3 is operated by a driver operating a shift lever 81 (see FIG. 5) of the shift operation device 8, for example, P range (parking range), N range (neutral range), D range (forward travel range), and the like. You can switch to

  In the automatic transmission 3 described above, the gear stage (shift stage) is set by engaging or releasing the brakes B1 and B2, which are friction engagement elements, in a predetermined state. The engagement / release state of the brakes B1 and B2 of the automatic transmission 3 is shown in the operation table of FIG. In the operation table of FIG. 3, “◯” represents “engaged”, and “blank” represents “release”.

  In the automatic transmission 3 of this example, the input shaft 30 (the rotation shaft of the second motor generator MG2) and the output shaft 33 (the ring gear shaft 21) can be disconnected by releasing both the brakes B1 and B2. Neutral state).

  The transmission gear stage “Lo” is set by engaging the brake B2 and releasing the brake B1. When the brake B2 is engaged, the rotation of the ring gear R32 of the second planetary gear mechanism 32 is fixed, and the carrier CA32, that is, the output shaft is generated by the ring gear R32 to which the rotation is fixed and the sun gear S32 rotated by the second motor generator MG2. 33 rotates at a low speed.

  The transmission gear stage “Hi” is set by engaging the brake B1 and releasing the brake B2. When the brake B1 is engaged, the rotation of the sun gear S31 of the first planetary gear mechanism 31 is fixed, and the rotation of the sun gear S31 (ring gear 31) rotated by the second motor generator MG2 is fixed by the rotation of the sun gear S31. The carrier CA32 (carrier CA31), that is, the output shaft 33 rotates at a high speed.

  In the automatic transmission 3 described above, the upshift from “Lo” to “Hi” is achieved by clutch-to-clutch shift control in which the brake B2 is released and the brake B1 is engaged at the same time. Further, the down shift from “Hi” to “Lo” is achieved by clutch-to-clutch shift control in which the brake B1 is released and the brake B2 is engaged at the same time. The hydraulic pressure when the brakes B1 and B2 are engaged or released is controlled by a hydraulic pressure control circuit 300 (see FIG. 4).

-Hydraulic control circuit-
The hydraulic control circuit 300 is provided with a linear solenoid valve and a control valve, which will be described later, and controls the excitation and non-excitation of the solenoid valve to switch the hydraulic circuit so that the brakes B1 and B2 of the automatic transmission 3 are engaged. You can control merge and release. Excitation / de-excitation of the linear solenoid valve of the hydraulic control circuit 300 is controlled by a solenoid control signal (instructed hydraulic signal) from the ECU 100.

  FIG. 4 shows a schematic configuration of the hydraulic control circuit 300. As shown in FIG. 4, the hydraulic control circuit 300 is driven by the rotation of the engine 1 and supplies oil (automatic transmission fluid: ATF) with an oil flow with sufficient pumping performance to operate the brakes B1 and B2. A mechanical pump MP that is pumped to the passage 301, a three-way solenoid valve 302 and a pressure control valve 303 that adjust the line hydraulic pressure PL of the oil pumped from the mechanical pump MP to the oil passage 301, and a line hydraulic pressure PL are used. And linear solenoid valves 304 and 305 for adjusting the engagement force of the brakes B1 and B2, control valves 306 and 307, and accumulators 308 and 309.

  In this hydraulic control circuit 300, the line hydraulic pressure PL can be adjusted by driving the 3-way solenoid valve 302 to control the opening and closing of the pressure control valve 303.

  The engaging force of the brakes B1 and B2 is adjusted by controlling the opening and closing of the control valves 306 and 307 that transmit the line hydraulic pressure PL to the brakes B1 and B2 by controlling the current applied to the linear solenoid valves 304 and 305. can do.

  In the hydraulic control circuit 300, excess oil that has not been used for the operation of the brakes B1 and B2 among the oil pumped from the mechanical pump MP, and pressure control after being used for the operation of the brakes B1 and B2. The oil returned from the valve 303 is supplied as lubricating oil to the power distribution mechanism 2 or the like via the oil flow path 310.

-Shift operation device-
On the other hand, a shift operation device 8 as shown in FIG. 5 is arranged in the vicinity of the driver seat of the hybrid vehicle HV. The shift operating device 8 is provided with a shift lever 81 that can be displaced.

  In this example, the shift operation device 8 has a P (parking) position, an R (reverse) position, an N (neutral) position, and a D (drive) position, and the driver moves the shift lever 81 to a desired position. Can be displaced. Each position of these P position, R position, N position, and D position (including the shift up (+) position and shift down position (−) position of the S position described below) is determined by the shift position sensor 206 (see FIG. 6). Detected.

  The P position and the N position are non-traveling positions that are selected when the vehicle is not traveling, and the R position and the D position are traveling positions that are selected when the vehicle is traveling.

  Further, as shown in FIG. 5B, the shift operation device 8 is provided with an S (sequential) position 82, and when the shift lever 81 is operated to the S position 82, a manual shift operation is performed. A sequential mode (manual shift mode) is set.

  In this example, for example, six sequential shift ranges S1 to S6 are set, and when the shift lever 81 is operated to upshift (+) or downshift (−), the sequential shift range is up or down. . For example, the sequential shift range is increased by one stage for each operation to upshift (+) (for example, S1 → S2 →... → S6). On the other hand, the sequential shift range is decremented by one stage (for example, S6 → S5 →... → S1) for each operation to the downshift (−).

  The shift range control when the sequential mode is set uses, for example, the vehicle speed (output shaft speed) and the engine speed as parameters, and the target speed (engine speed) is set for each sequential shift range S1 to S6. Using the set map, based on the current vehicle speed and the position information of the sequential shift range selected by the shift lever operation, the target rotational speed is obtained with reference to the map, and the actual engine rotational speed is obtained as the target rotational speed. Is executed by a method of controlling the operating state of the first motor generator MG1 connected to the power distribution mechanism 2 so that the two coincide with each other. Further, in the above map, the target rotational speed is set so that the sequential shift range S1 is the highest when the vehicle speed is the same, and decreases toward the sequential shift range S6. For example, the sequential shift range is “ When the engine is downshifted from “S3” to “S2”, the engine speed increases. Further, when the shift range is upshifted from “S3” to “S4”, the engine speed is reduced.

-ECU-
As shown in FIG. 6, the ECU 100 includes a CPU 101, a ROM 102, a RAM 103, a backup RAM 104, and the like.

  The ROM 102 includes various programs including a program for executing a shift control for setting the gear stage of the automatic transmission 3 in accordance with the traveling state of the hybrid vehicle HV, in addition to the control related to the basic operation of the hybrid vehicle HV. It is remembered. Specific contents of this shift control will be described later.

  The CPU 101 executes arithmetic processing based on various control programs and maps stored in the ROM 102. The RAM 103 is a memory that temporarily stores calculation results of the CPU 101, data input from each sensor, and the like. The backup RAM 104 is a non-volatile memory that stores data to be saved when the engine 1 is stopped. is there.

  The CPU 101, ROM 102, RAM 103, and backup RAM 104 are connected to each other via a bus 106 and to an interface 105.

  The interface 105 of the ECU 100 includes an engine speed sensor 201, a throttle opening sensor 202 that detects the throttle valve opening of the engine 1, an input shaft speed sensor 203, an output shaft speed sensor 204, and an accelerator pedal opening. An accelerator opening sensor 205 for detecting, a shift position sensor 206 for detecting the position of the shift lever 81, a current sensor 207 for detecting a charge / discharge current of the battery 5, a battery temperature sensor 208, and the like are connected. A signal from the sensor is input to the ECU 100.

  The ECU 100 executes various controls of the engine 1 including throttle opening (intake amount) control, fuel injection amount control, ignition timing control and the like of the engine 1 based on the output signals of the various sensors described above.

  The ECU 100 outputs a solenoid control signal (instructed hydraulic signal) to the hydraulic control circuit 300 of the automatic transmission 3. Based on this solenoid control signal, the linear solenoid valve and the like of the hydraulic control circuit 300 are controlled, and the brakes B1 and B2 are engaged or released to a predetermined state so as to constitute a predetermined gear stage (Lo or Hi). The Further, ECU 100 calculates a state of charge (SOC) based on the integrated value of the charge / discharge current detected by current sensor 207 in order to manage battery 5. Further, ECU 100 controls inverter 4, and the regeneration or power running (assist) of first motor generator MG <b> 1 and second motor generator MG <b> 2 is controlled by the control of inverter 4.

  Then, the ECU 100 performs the following “shift control”, “travel control”, and “engagement hydraulic pressure control during downshift”.

-Shift control-
First, the ECU 100 calculates the accelerator opening Ac based on the output signal of the accelerator opening sensor 205, and calculates the vehicle speed V based on the output signal of the output shaft rotational speed sensor 204, and determines the accelerator opening Ac and the vehicle speed. Based on V, the required torque Tr is obtained with reference to the map shown in FIG.

  Next, the target gear stage is calculated with reference to the shift map shown in FIG. 8 based on the vehicle speed V and the required torque Tr, and the rotation obtained from the output signals of the input shaft rotational speed sensor 203 and the output shaft rotational speed sensor 204. Whether the current gear stage of the automatic transmission 3 is determined based on the ratio of the numbers (output shaft rotational speed / input shaft rotational speed), and whether the speed change operation is necessary by comparing the target gear stage with the current gear stage. Determine whether or not.

  According to the determination result, when there is no need for shifting (when the target gear stage and the current gear stage are the same and the gear stage is appropriately set), a solenoid control signal (indicated hydraulic pressure) that maintains the current gear stage. Signal) to the hydraulic control circuit 300 of the automatic transmission 3.

  On the other hand, when the target gear stage and the current gear stage are different, shift control is performed. For example, the traveling state of the hybrid vehicle HV changes (for example, the vehicle speed changes) from the state in which the gear stage of the automatic transmission 3 is traveling in the “Hi” state, for example, from point A to point B shown in FIG. In this case, the target gear stage calculated from the shift map becomes “Lo”, and a solenoid control signal (instructed hydraulic signal) for setting the “Lo” gear stage is output to the hydraulic control circuit 300 of the automatic transmission 3. Then, at the same time as releasing the brake B1 as the friction engagement element, the shift from the Hi gear to the Lo gear (Hi → Lo down shift) is performed by engaging the brake B2.

  The map for calculating the required torque shown in FIG. 7 is a map obtained by empirically obtaining the required torque Tr by experiment / calculation using the vehicle speed V and the accelerator opening Ac as parameters, and is stored in the ROM 102 of the ECU 100. Has been.

  Further, the shift map shown in FIG. 8 uses the vehicle speed V and the required torque Tr as parameters, and has two regions (Lo region and Hi region) for obtaining an appropriate gear according to the vehicle speed V and the required torque Tr. It is a set map and is stored in the ROM 102 of the ECU 100. In the shift map of FIG. 8, the upshift line (shift line) is indicated by a solid line, and the downshift line (shift line) is indicated by a broken line. In addition, each switching direction of upshifting and downshifting is indicated by arrows in the figure.

  Even when the above-described sequential mode is selected, the automatic transmission 3 may be down when the shift state of the shift vehicle shown in FIG. Shift or upshift.

-Travel control-
The ECU 100 calculates the required torque Tr to be output to the ring gear shaft (output shaft) 21 with reference to the map shown in FIG. 7 based on the accelerator opening degree Ac and the vehicle speed V by the same processing as described above, and this required torque. The hybrid vehicle HV travels in a predetermined travel mode by drivingly controlling the engine 1 and the motor generators MG1, MG2 (inverter 4) so that the required power corresponding to Tr is output to the ring gear shaft 21.

  For example, in a region where the engine efficiency is low, such as when starting or running at low speed, the operation of the engine 1 is stopped, and power corresponding to the required power is transferred from the second motor generator MG2 to the ring gear shaft 21 via the automatic transmission 3. Output. During normal travel, the engine 1 is driven so that power commensurate with the required power is output from the engine 1, and the rotation speed of the engine 1 is controlled by the first motor generator MG1 so as to achieve optimum fuel consumption.

  When assisting the torque by driving the second motor generator MG2, the gear stage of the automatic transmission 3 is set to Lo and the torque applied to the ring gear shaft (output shaft) 21 is increased when the vehicle speed V is low. In the state where the vehicle speed V increases, the gear stage of the automatic transmission 3 is set to Hi, and the rotational speed of the second motor generator MG2 is relatively decreased to reduce the loss, thereby executing efficient torque assist. To do. Further, the operation of the second motor generator MG2 is stopped, and the torque (direct torque) transmitted directly from the engine 1 to the ring gear shaft 21 via the power distribution mechanism 2 while taking the reaction force of the engine torque by the first motor generator MG1. ) Is also executed.

  The ECU 100 normally supplies an equal power command to the second motor generator MG2 so that the input torque of the automatic transmission 3 becomes equal power (input shaft speed × input torque = constant). MG2 is controlled with equal power.

-Engagement hydraulic control during downshifting-
First, in the hybrid vehicle HV, when the accelerator pedal is depressed during the downshift (when the power is turned on and downshift), the shift shock is reduced and the friction of the friction engagement elements (brakes B1 and B2) of the automatic transmission 3 is reduced. Although it is necessary to reduce the torque of the second motor generator MG2 during gear shifting in order to reduce the material heat load, etc., as described above, when the engine 1 is at a high speed, protection control is activated and the torque is reduced. Can not do it. In other words, if the engine speed increases during gear shifting, the first motor generator MG1 responsible for the reaction force of the engine torque is executed to prevent over-rotation of the engine 1 (part protection), so the amount of power generation is reduced. To increase. When the power generation amount increases in this way, power consumption in the second motor generator MG2 is required, and a desired torque reduction cannot be performed.

  For this reason, if the torque reduction cannot be performed during the downshift, it is impossible to limit the blowing of the second motor generator MG2, which is the gear to be shifted, and therefore the rotation speed of the second motor generator MG2 and the engagement target rotation speed. The friction engagement element (the brake B1 or B2) is engaged in a state where there is a differential rotation with respect to the (synchronous rotation speed of the target shift stage), and an engagement shock may occur.

  In consideration of such points, in this example, even during a downshift, even if the engine is at a high speed and the torque of the second motor generator MG2 cannot be reduced due to the protection control, Realizes control capable of suppressing shock.

  A specific example of the control will be described with reference to the flowchart of FIG. The control routine of FIG. 9 is repeatedly executed in the ECU 100 every predetermined time (for example, several milliseconds).

  First, in step ST1, it is determined whether or not the power is ON (determined by the output signal of the accelerator opening sensor 205) and downshift is being performed. If the determination result is affirmative, the process proceeds to step ST2. If the determination result in step ST1 is negative (when the power-on downshift is not being performed), the process returns.

  In step ST2, it is determined whether the engine speed read from the output signal of the engine speed sensor 201 is equal to or greater than a determination threshold value. If the determination result in step ST2 is affirmative (engine speed ≧ determination threshold), it is determined (predicted) that “the torque reduction of the second motor generator MG2 cannot be performed during downshifting”, and the process proceeds to step ST3. move on. If the determination result in step ST2 is negative (engine speed <determination threshold), the process returns.

  Here, the determination threshold set for the engine speed is the upper limit speed of the engine 1 itself, the upper limit speed of the rotating body of the driving force transmission system (for example, the pinion gear P21 of the power distribution mechanism 2), and the first motor. This is determined in consideration of the upper limit rotational speed of generator MG1. Specifically, in the hybrid vehicle HV, for example, as shown in FIG. 10, the allowable rotational speed of the engine 1 is determined to protect the engine 1 itself and to protect the pinion gear P21 and the first motor generator MG1. The engine speed is controlled (protective control) by the first motor generator MG1 so that the upper limit value of the permissible speed is not exceeded, and a margin is expected for the upper limit value of the permissible speed. The value (allowable rotation speed upper limit value−margin) is set as a determination threshold value. Note that this determination threshold value may be variably set in consideration of the power reception state of the battery 5 and the vehicle speed as described above.

  In step ST3, the friction engagement element on the engagement side of the automatic transmission 3 during the downshift, that is, the gain Ga of the apply hydraulic pressure Pb2 of the brake B2, is set to a value larger than the gain in the normal control. Here, the relationship between the apply hydraulic pressure Pb of the brake B2 and the gain Ga can be expressed as [Pb2 = Tb2 * K * Ga + Prtn]. By increasing the gain Ga in this equation, the engagement pressure of the brake B2 is normally set. The engagement pressure during the control can be increased (see FIG. 11), and the engagement of the brake B2 can be completed early. Tb2 is a motor torque (torque of the second motor generator MG2), and K is a conversion coefficient of [torque → hydraulic pressure]. Prtn is a return end hydraulic pressure, which is a hydraulic pressure at which the brake B2 starts to have a torque capacity.

  Here, the gain Ga of the apply hydraulic pressure Pb is a value empirically obtained by experiments, calculations, and the like in consideration of suppression of rotation increase (motor blow) of a second motor generator MG2 (described later) and engagement shock. Set.

  Then, the pressure increase control of the engagement hydraulic pressure of the brake B2 on the engagement side is performed using Pb2 with the gain Ga increased in this way as a hydraulic pressure command value (step ST4).

  As described above, according to the control of this example, when the engine 1 becomes a high speed during the downshift and the torque reduction of the second motor generator MG2 cannot be performed due to the protection control, the automatic transmission 3 Because the gain Ga of the applied hydraulic pressure of the friction engagement element (brake B2) on the engagement side is set higher than that during normal control and the pressure increase of the engagement hydraulic pressure is set faster than during normal control, The time required to complete the engagement of the brake B2 can be shortened. As a result, as shown in FIG. 11, it is possible to suppress the rotation increase (blow of the motor) of the second motor generator MG2, and even if the torque reduction of the second motor generator MG2 cannot be performed, the friction engagement element The differential rotation between the motor rotation speed (motor rotation speed) and the engagement target rotation speed (synchronous rotation speed of the target gear stage) during engagement can be reduced. As a result, the engagement shock can be reduced.

  In this example, the sequential mode can be selected by operating the shift operating device 8, and the engine 1 is likely to be at a high speed during downshifting during sports driving in which the sequential mode is selected. The importance of the engagement pressure boosting control of FIG. 9 is higher than that during traveling, and by performing the engagement pressure increasing control, the heat of the second motor generator MG2 at the time of downshift gear shifting during sequential mode traveling. The load can be reduced.

-Other embodiments-
In the above example, the increase in the engagement pressure of the friction engagement element (brake B2) is made higher than the gain during normal control by increasing the gain Ga of the engagement hydraulic pressure, However, the present invention is not limited to this, and a predetermined hydraulic pressure may be added to the engagement hydraulic pressure at the time of normal control to increase the engagement pressure of the friction engagement element, or as shown in FIG. It is also possible to speed up the engagement pressure of the friction engagement element by setting the pressure increase start timing to a timing earlier than that during normal control.

  Also, a method of setting the gain Ga of the engagement hydraulic pressure higher than the gain at the time of normal control, a method of setting the engagement hydraulic pressure higher by adding a predetermined hydraulic pressure to the engagement hydraulic pressure at the time of normal control, or Of the methods for setting the pressure increase start timing to a timing faster than that during normal control, any two methods or a combination of all the methods are implemented to increase the pressure increase of the friction engagement element. May be.

  Here, the control for increasing the increase in the engagement pressure of the friction engagement element is a control that is performed when the torque reduction of the second motor generator MG2 cannot be performed, and is a special control that is different from the normal control. Therefore, during the execution of the engagement pressure increase control, the engagement pressure learning of the friction engagement element (for example, engagement pressure learning for stabilizing the downshift operation) is prohibited, and the normal control due to the erroneous learning is performed. It is preferable to eliminate the adverse effects on.

  In the above example, an example in which the present invention is applied to control of a vehicle equipped with an automatic transmission with two forward shifts is shown, but the present invention is not limited to this, and other examples such as forward four shifts, etc. The present invention can also be applied to control of a vehicle equipped with a planetary gear type automatic transmission having an arbitrary speed.

  In the above example, the example in which the present invention is applied to the control of a vehicle equipped with a gasoline engine has been shown. However, the present invention is not limited to this, and the present invention is also applicable to the control of a vehicle equipped with another engine such as a diesel engine. Applicable. Furthermore, the present invention is not limited to an FR (front engine / rear drive) type vehicle, but can also be applied to control of an FF (front engine / front drive) type vehicle or a four-wheel drive vehicle.

  An example of the FF type hybrid vehicle is shown in FIG.

  The hybrid vehicle shown in FIG. 13 includes an engine 1, a first motor generator MG1, a second motor generator MG2, a power distribution mechanism 2, an automatic transmission 3, a gear mechanism 500, a differential gear 6, a drive wheel 7, and the like. Yes.

  In the hybrid vehicle of this example, the rotation shaft of the second motor generator MG2 is connected to the input shaft of the automatic transmission 3. The output shaft of the automatic transmission 3 is coupled to the ring gear shaft 21 of the power distribution mechanism 2, and the power from the second motor generator MG 2 is driven through the automatic transmission 3, the gear mechanism 500, and the differential gear 6. 7 to output to.

  In the hybrid vehicle of this example, the power distribution mechanism 2 has the same structure as that shown in FIG. Further, the automatic transmission 3 has the same structure as that shown in FIG. 2, and the upshift from “Lo” to “Hi” is performed by the clutch-to-clutch shift control that releases the brake B2 and engages the brake B1 at the same time. A downshift from "Hi" to "Lo" is achieved by clutch-to-clutch shift control that is achieved and releases the brake B1 and simultaneously engages the brake B2.

  Also in the hybrid vehicle shown in FIG. 13, if the torque reduction cannot be performed during the power-on downshift, the blow of the second motor generator MG2 that is the shift target cannot be restricted, and an engagement shock may occur. However, even in the hybrid vehicle having such a configuration, by executing the engagement hydraulic pressure control shown in FIG. 9, the engine 1 becomes a high speed during the downshift, and the second motor generator MG2 is operated by the protection control. Even when the torque reduction cannot be performed, the engagement shock can be suppressed.

It is a schematic structure figure showing an example of a hybrid vehicle to which the present invention is applied. It is a schematic block diagram of the automatic transmission mounted in the hybrid vehicle of FIG. It is an operation | movement table | surface of the automatic transmission shown in FIG. It is a circuit block diagram which shows a part of hydraulic control circuit of an automatic transmission. It is a figure which writes and shows the principal part perspective view (a) of a shift operation apparatus, and the shift gate (b) of a shift operation apparatus. It is a block diagram which shows the structure of control systems, such as ECU. It is a figure which shows an example of the map used for request | requirement torque calculation. It is a figure which shows an example of the shift map used for shift control. It is a flowchart which shows an example of the engagement hydraulic pressure control at the time of the downshift gear change which ECU performs. It is a figure which shows the allowable rotation speed of an engine. It is a figure which shows an example of the oil pressure command value and MG2 rotation speed of brake B2 by the side of engagement at the time of a downshift. It is a figure which shows the other example of the hydraulic pressure command value of brake B2 by the side of engagement at the time of a downshift. It is a schematic block diagram which shows the other example of the hybrid vehicle to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Power distribution mechanism 21 Ring gear shaft S21 Sun gear R21 Ring gear P21 Pinion gear CA21 Carrier 3 Automatic transmission 30 Input shaft 33 Output shaft 300 Hydraulic control circuit B1, B2 Brake (friction engagement element)
4 Inverter 5 Battery (power storage device)
7 Drive Wheel 8 Shift Operation Device S Sequential Position MG1 First Motor Generator MG2 Second Motor Generator 100 ECU
201 Engine speed sensor

Claims (8)

By engaging or releasing a friction engagement element in a predetermined state, an engine and an electric motor that output a driving force for traveling, a power storage device that can charge electric power generated from the electric motor and supply electric power to the electric motor, An automatic transmission that sets a plurality of gear stages, and a vehicle control device that outputs power from the electric motor to drive wheels via the automatic transmission.
A determination means for determining whether or not torque reduction of the motor cannot be performed during a downshift, and a friction engagement element on the engagement side of the automatic transmission when torque reduction of the motor cannot be performed. An apparatus for controlling a vehicle, comprising: an engagement pressure increasing means for increasing the combined pressure faster than the normal control. The vehicle control device according to claim 1,
The vehicle control apparatus according to claim 1, wherein the determination unit determines that torque reduction of the electric motor cannot be performed when the engine speed is equal to or greater than a determination threshold value. The vehicle control device according to claim 2,
The vehicle control device, wherein the determination threshold value is variably set in consideration of one or both of a power acceptance state and a vehicle speed of the power storage device. In the control apparatus of the vehicle as described in any one of Claims 1-3,
The engagement pressure increasing means sets a control gain of the engagement hydraulic pressure of the friction engagement element to be higher than a gain during normal control to increase the increase of the engagement pressure of the friction engagement element. A vehicle control device. In the control apparatus of the vehicle as described in any one of Claims 1-3,
The engagement pressure raising means increases the engagement pressure of the friction engagement element faster by adding a predetermined oil pressure to the engagement oil pressure during normal control of the friction engagement element. Control device. In the control apparatus of the vehicle as described in any one of Claims 1-3,
The engagement pressure increasing means speeds up the increase of the engagement pressure of the friction engagement element by setting the pressure increase start timing of the engagement hydraulic pressure of the friction engagement element to a timing faster than that during normal control. A vehicle control device characterized by the above. In the control apparatus of the vehicle as described in any one of Claims 1-3,
The engagement pressure raising means sets a control gain of the engagement hydraulic pressure of the friction engagement element to be higher than a gain during normal control, and sets a predetermined hydraulic pressure to the engagement hydraulic pressure during normal control of the friction engagement element. By executing either one of the two methods or a combination of all the methods among the method of adding, or the method of setting the pressure increase start timing of the engagement hydraulic pressure of the friction engagement element to a timing that is faster than the normal control time. A control apparatus for a vehicle, wherein the increase in the engagement pressure of the friction engagement element is accelerated. In the vehicle control device according to any one of claims 1 to 7,
During execution of control for increasing the pressure of the friction engagement element to be increased, learning of the engagement pressure of the friction engagement element is prohibited.

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