JP5691658B2 - Control device for vehicle power transmission device - Google Patents

Description

  The present invention relates to a control device for a vehicle power transmission device that performs lock-up slip control when a vehicle starts.

  2. Description of the Related Art A vehicle having a lock-up clutch capable of directly connecting between input and output of a fluid transmission device (for example, a torque converter or a fluid coupling) that transmits engine power to a transmission such as a continuously variable transmission or a multi-stage transmission is well known. ing. For example, this is the vehicle described in Patent Document 1. In general, such a lock-up clutch is determined to be engaged / released based on a vehicle state from a preset relationship for the purpose of improving fuel consumption, for example, when the running state of the vehicle enters a lock-up region. Lock-up control is started. Furthermore, slip control (lock-up slip control, flex lock-up control) that enables a lock-up operation in a wide driving range by giving a predetermined slip to the lock-up clutch based on the vehicle state from the above-described relationship. By implementing this, it is possible to expand the lock-up control region and improve fuel efficiency. In such slip control, for example, the torque capacity of the lockup clutch is controlled by feedback control so that the difference between the input and output rotational speeds of the lockup clutch (differential rotational speed between input and output, slip rotational speed, slip amount) is set as a target value. I have control.

  In addition, when starting the vehicle, the lockup clutch is actively grasped, and slip control of the lockup clutch is performed, for example, to suppress an increase in engine rotation speed (to suppress an increase in engine rotation speed). ) Start-up lock-up slip control (start-up slip control, flex start control) has also been proposed that improves fuel efficiency by utilizing a low-rotation high-torque region with relatively good engine combustion efficiency. Since the slip control at the time of starting is a control from the time of starting where the differential rotational speed of the lock-up clutch (for example, the rotational speed difference between the engine rotational speed and the turbine rotational speed restricted by the vehicle speed) is relatively large, feedback control is performed. Instead, for example, the torque capacity of the lockup clutch (that is, the slip amount of the lockup clutch) is controlled only by open control (feedforward control). FIG. 13 is a time chart showing an example of starting slip control. In the conventional example of FIG. 13, the solenoid valve SLU is used for controlling the slip amount of the lock-up clutch, and when starting the vehicle, the lock-up clutch pressure in the start-time slip control with respect to the solenoid valve SLU by feed-forward control. A command value (SLU command pressure) is output, and an increase in engine rotation speed is suppressed by slip engagement of the lockup clutch.

  Here, in the solenoid valve that controls the slip amount of the lockup clutch as described above, the characteristic (I / P characteristic) of the output pressure P corresponding to the drive current I corresponding to the lockup clutch pressure command value is the initial quality. There is a hardware variation that swings positively and negatively (for example, ± several tens [kPa]), and the torque capacity (lockup clutch torque) of the lockup clutch with respect to the lockup clutch pressure command value varies. For this reason, the solenoid valve whose I / P characteristic swings to the maximum on the positive side has excessive torque capacity (lockup clutch torque) of the lockup clutch at the time of vehicle start-up due to the lockup clutch pressure command value in the start slip control. (That is, the lock-up clutch is grasped too much immediately after starting the vehicle), and the engine rotational speed fluctuates as shown in FIG. 13, and torque fluctuation or shock may occur. On the other hand, it is conceivable to lower the initial conforming value (the lockup clutch pressure command value in the slip control at the start), but in this case, the solenoid valve in which the I / P characteristic does not swing maximum on the positive side is considered. Therefore, it is not possible to appropriately suppress the increase in the engine speed at the start of the vehicle, and the fuel efficiency improvement effect may be reduced. Therefore, it is conceivable to cope with hardware variations and secular changes by correcting the lock-up clutch pressure (the lock-up clutch pressure command value agrees) in the starting slip control by learning for each vehicle.

JP 2006-29464 A JP 2006-336854 A

  By the way, when starting a vehicle, there are many variations of hardware dependence (for example, engine torque stability at start-up, friction coefficient change accompanying change in slip speed of lockup clutch, accelerator pedal play, etc.). It is difficult to stably detect variations in the lock-up clutch torque, and it may be difficult to stably learn the lock-up clutch pressure in the starting slip control. Therefore, the lockup clutch pressure is learned during the slip control during steady running where the characteristics other than the solenoid are relatively stable (for example, the acceleration range where the vehicle running is stable), and the learning value (or learning correction amount) at that time is learned. There is a method of reflecting the lock-up clutch pressure in the slip control at the start. However, due to the recent expansion of the lock-up area, the frequency of slip control during steady running is reduced, and as a result, the number of times of learning is reduced, and the lock-up clutch pressure command in the starting slip control is reflected without the learning value converging. If the starting slip control is repeatedly executed using the value, there is a possibility that a shock continuously occurs. In addition, the engine torque usage range, the lockup clutch pressure command value usage range, and the allowable range of deterioration in drivability are different between steady running and vehicle start. May not be reflected in the slip control when starting. Therefore, it is desirable to independently learn the lockup clutch pressure even when the vehicle starts. It is to be noted that such a problem is not known, and even when the vehicle starts with many hardware-dependent variation factors, it is possible to stably detect the variation in the lockup clutch torque at the time of the vehicle start transition, and the same as during steady running However, it has not yet been proposed to learn the lock-up clutch pressure stably.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is to stably learn the lock-up clutch pressure in the lock-up slip control at the start even when the vehicle starts. Another object of the present invention is to provide a control device for a vehicle power transmission device.

The subject matter of the first invention for achieving the above object is as follows: (a) a lockup clutch capable of directly connecting between input and output rotating members of a fluid transmission device for transmitting engine power to an automatic transmission; a control device for a vehicular power transmitting device to perform the lock-up clutch start-time lock-up slip control for slip-engaged the time of starting the vehicle, (b) before SL lock-up clutch in the start-time lock-up slip control Only when the differential rotational speed becomes maximum, when the actual engine rotational speed is lower than the target engine rotational speed that increases according to the estimated value of the engine torque when the differential rotational speed is maximum, The lock-up clutch pressure in the start-up lock-up slip control is corrected to the reduced pressure side by learning.

Thus, in only when the differential rotation speed before SL lock-up clutch in the start-time lock-up slip control is maximized, the actual engine rotational speed, when the differential rotation speed is maximum engine When the engine speed is lower than the target engine speed that increases in accordance with the estimated value of torque, the lockup clutch pressure in the start-up lockup slip control is corrected to the reduced pressure side by learning, so the amount of change in the engine speed (Change speed) becomes almost zero and the engine inertia can be ignored, or the capacity coefficient of the torque converter, which is a function of the speed ratio of the torque converter as a fluid transmission device, is set to a substantially constant state, and the vehicle start transient It is possible to stably detect variations in lockup clutch torque at the time. That is, it is possible to stably determine whether or not the lock-up clutch torque at the time of vehicle start transition is excessive. Therefore, by using the engine torque and engine speed when the differential rotation speed of the lock-up clutch is maximum, even in the transient state at the time of vehicle start with many hardware-dependent variation factors, The lockup clutch pressure can be learned stably.

  Here, according to a second aspect of the present invention, in the control device for a vehicle power transmission device according to the first aspect, the first lockup slip control is started after the start-up lockup slip control when the differential rotational speed is maximum. It is determined within a certain predetermined period for observing the occurrence phenomenon of the differential rotational speed during the lock-up slip control at the time of starting from the predetermined time until the second predetermined time elapses. There is. In this way, it is possible to accurately grasp the phenomenon of occurrence of the differential rotational speed during the lock-up slip control at the start-up that becomes larger as the engine blows and becomes smaller as the lock-up clutch slips. .

  According to a third aspect of the present invention, in the control device for a vehicle power transmission device according to the first aspect or the second aspect, when the actual engine speed is higher than the target engine speed. The lock-up clutch pressure in the start-up lock-up slip control is corrected to the pressure increasing side by learning. In this way, it is possible to stably learn the lockup clutch pressure in the lockup slip control at the start even when the vehicle is in a transitional state.

  According to a fourth aspect of the invention, in the control device for a vehicle power transmission device according to the third aspect of the invention, when it is determined that the actual engine rotational speed is higher continuously for a predetermined number of times, This is to correct the lockup clutch pressure in the time lockup slip control to the pressure increasing side by learning. In this way, the lockup clutch pressure can be corrected to the increased pressure side when it can be determined that the lockup clutch torque at the time of vehicle start-up transition is not sufficient. In other words, the correction to the pressure increase side of the lockup clutch pressure suppresses the increase in engine speed, which contributes to improving fuel efficiency but tends to deteriorate drivability. It is possible to place emphasis on drivability by carefully adjusting to.

  According to a fifth aspect of the present invention, in the control device for a vehicle power transmission device according to any one of the first to fourth aspects, the actual engine speed, the target engine speed, The larger the difference is, the larger the correction amount by learning is. In this way, the lockup clutch pressure is corrected more appropriately by learning.

  According to a sixth aspect of the present invention, in the control device for a vehicle power transmission device according to the fifth aspect, the correction amount is increased after the difference exceeds a predetermined value. In this way, the update frequency of the lock-up clutch pressure due to learning is suppressed, and the physical durability of the storage device (memory) that stores the learned value is improved.

  According to a seventh aspect of the present invention, in the control device for a vehicle power transmission device according to any one of the first to sixth aspects, the target engine rotational speed is the lockup slip at the start. An ideal engine when the above-mentioned differential rotational speed, which has been experimentally obtained in advance as the engine rotational speed reduced as much as possible in order to improve fuel efficiency within a range where deterioration of drivability is permitted during control, is maximum Rotation speed. In this way, it is possible to stably learn the lockup clutch pressure in the lockup slip control at the start even when the vehicle is in a transitional state.

It is a figure explaining the schematic structure of the power transmission path | route with which the vehicle to which this invention was applied was provided, and is a figure explaining the principal part of the control system provided in the vehicle. It is a skeleton diagram explaining composition of an automatic transmission etc. It is an action | operation chart explaining the relationship between the speed change operation | movement of an automatic transmission, and the combination of the action | operation of the engagement apparatus used for it. It is a circuit diagram regarding the operation control etc. of a lockup clutch among hydraulic control circuits. It is a functional block diagram explaining the principal part of the control function of an electronic controller. It is a figure which shows an example of the engine torque map memorize | stored beforehand. It is a figure which shows an example of LU clutch pressure command value set when performing slip control at the time of starting, and slip control at the time of steady state. Is a diagram showing an example of the relationship (map) having a target line determined experimentally in advance of the N _S maximum when the engine rotational speed N _E max and the engine torque T _E. It is a figure which shows an example of the relationship (operation characteristic figure) of the capacity | capacitance coefficient and speed ratio of a torque converter. It is a figure which shows an example of the relationship (correction amount map) calculated | required experimentally beforehand by the difference and the correction amount by learning. 7 is a flowchart for explaining a control operation for stably learning a lock-up clutch pressure in the slip control at the start even when the vehicle is started, that is, the main part of the control operation of the electronic control device. It is a time chart corresponding to the control action of FIG. It is a time chart which shows the prior art example of the slip control at the time of start.

  In the present invention, as the engine, for example, a gasoline engine such as an internal combustion engine that generates power by combustion of fuel, a diesel engine, or the like is preferably used, but another prime mover such as an electric motor is combined with the engine. It can also be adopted.

  Preferably, the start-up lock-up slip control is feed-forward control in which a lock-up clutch pressure command value is set according to an acceleration request amount for the vehicle so as to suppress the engine speed from rising. is there.

  Preferably, in the automatic transmission, for example, a plurality of gear stages (shift speeds) are alternatively achieved by selectively connecting rotating elements of a plurality of sets of planetary gear devices by an engagement device. A known planetary gear type automatic transmission, in which a plurality of pairs of transmission gears that are always meshed is provided between two shafts, and one of the plurality of pairs of transmission gears is alternatively in a power transmission state by a synchronization device. Although it is a two-shaft transmission, a synchronous mesh type parallel two-shaft automatic transmission and a synchronous mesh type parallel two-shaft automatic transmission that can be automatically switched by a synchronizer driven by a hydraulic actuator. However, a so-called DCT (Dual Clutch Transmission), a power transmission member, which is a type of transmission having two input shafts, each of which has a clutch connected to the input shaft of each system and is further connected to an even number stage and an odd number stage. A so-called belt-type continuously variable transmission in which a transmission belt functioning around a pair of variable pulleys with variable effective diameters is wound around a pair of variable pulleys, and the gear ratio is continuously changed steplessly. A plurality of rollers that can rotate at the center of rotation intersecting the center of the cone and the shaft center are sandwiched between the pair of cones, and the crossing angle between the center of rotation of the roller and the shaft center is changed to change the transmission ratio. It is constituted by a so-called traction type continuously variable transmission which is variable. Further, the mounting posture of the automatic transmission with respect to the vehicle may be a horizontal installation type such as an FF (front engine / front drive) vehicle in which the axis of the automatic transmission is in the width direction of the vehicle. It may be a vertical installation type such as an FR (front engine / rear drive) vehicle in the longitudinal direction.

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

  FIG. 1 is a diagram for explaining a schematic configuration of a power transmission path from an engine 14 to a drive wheel 32 provided in a vehicle 10 to which the present invention is applied, as well as output control of the engine 14 and shift of an automatic transmission 18. It is a figure explaining the principal part of the control system provided in the vehicle 10 for control etc. FIG. 2 is a skeleton diagram illustrating the automatic transmission 18 and the like. The torque converter 16, the automatic transmission 18, and the like are substantially symmetrical with respect to the center line (axial center RC), and the lower half of the center line is omitted in FIG. 2 is a rotational axis of the engine 14 and the torque converter 16.

  1 and 2, a vehicle power transmission device 12 (hereinafter referred to as a power transmission device 12) is provided in a transaxle case 20 (hereinafter referred to as a case 20) as a non-rotating member attached to a vehicle body by bolting or the like. A torque converter 16, an automatic transmission 18, and the like are provided in order from the engine 14 side on the axis RC. The power transmission device 12 includes a differential gear 26 (differential gear) 28 that integrally includes a differential ring gear 26 that meshes with an output gear 24 that is an output rotating member of the automatic transmission 18, and a differential gear thereof. A pair of axles 30 connected to the device 28 is provided. The power transmission device 12 configured in this manner is suitably used for, for example, an FF (front engine / front drive) type vehicle 10. In the power transmission device 12, the power of the engine 14 is supplied from the crankshaft 15 to the torque converter 16, the automatic transmission 18, the diffring gear 26, the differential gear device 28, the pair of axles 30, and the like in order. It is transmitted to the drive wheel 32.

  The torque converter 16 is a fluid transmission device that transmits power through a fluid between the pump impeller 16p and the turbine impeller 16t. The pump impeller 16p is connected to the engine 14 via the crankshaft 15, and is an input side rotating element of the torque converter 16 that receives the driving force from the engine 14 and can rotate about the axis RC. The turbine impeller 16t is an output side rotating element of the torque converter 16, and is connected to an input shaft 19 which is an input rotating member of the automatic transmission 18 so as not to be relatively rotatable by spline fitting or the like. Further, a lock-up clutch 34 is provided between the pump impeller 16p and the turbine impeller 16t, which can be directly connected between them, that is, between the input / output rotating members of the torque converter 16. Further, the pump impeller 16p is supplied with an operating hydraulic pressure as a source pressure for controlling the shift of the automatic transmission 18, controlling the operation of the lockup clutch 34, or supplying lubricating oil to each part. A mechanical oil pump 22 that is generated by being rotationally driven by 14 is connected.

Lockup clutch 34, as is well known, has a mechanism for differential rotation slipped friction material occurs, the hydraulic pressure P _ON and the release side fluid in the engagement side oil chamber 16on by the hydraulic control circuit 100 This is a hydraulic friction clutch that is frictionally engaged with the front cover 16c by controlling a differential pressure ΔP (= P _ON −P _OFF ) with respect to the hydraulic pressure P _OFF in the chamber 16off (see FIG. 4). The operating state of the torque converter 16 is, for example, so-called lockup release (lockup off) in which the differential pressure ΔP is negative and the lockup clutch 34 is released, and the differential pressure ΔP is zero or more and the lockup clutch 34 is A so-called lock-up slip state (slip state) half-engaged with slip, and a so-called lock-up state (engaged state, lock-up) in which the differential pressure ΔP is maximized and the lock-up clutch 34 is completely engaged. On). For example, when the lock-up clutch 34 is completely engaged (lock-up on), the pump impeller 16p and the turbine impeller 16t are integrally rotated, and the power of the engine 14 is directly transmitted to the automatic transmission 18 side. Is done. Further, by controlling the differential pressure ΔP so as to be slip-engaged in a predetermined slip state, for example, input / output rotational speed difference (that is, slip rotational speed (slip amount, differential rotational speed) = engine rotational speed N _E -turbine The rotational speed N _T ) N _S is feedback controlled, so that when the vehicle 10 is driven (power on), the turbine shaft is rotated following the crankshaft 15 with a predetermined slip amount, while the vehicle is not driven (power off). ) Occasionally, lock-up slip control is performed in which the crankshaft 15 is rotated following the turbine shaft with a predetermined slip amount. In the slip state of the lock-up clutch 34, for example, when the differential pressure ΔP is set to zero, the torque sharing of the lock-up clutch 34 is lost, and the torque converter 16 is operated under the same operating conditions as the lock-up off. The

  The automatic transmission 18 constitutes a part of a power transmission path from the engine 14 to the drive wheels 32, and is re-engaged by any of a plurality of hydraulic friction engagement devices (that is, engagement of the hydraulic friction engagement devices). And a planetary gear type multi-stage transmission that functions as a stepped automatic transmission in which a plurality of shift stages (gear stages) are selectively established by shifting. For example, it is a stepped transmission that performs a so-called clutch-to-clutch shift that is often used in known vehicles. This automatic transmission 18 has a single pinion type first planetary gear device 36, a double pinion type second planetary gear device 38 and a single pinion type third planetary gear device 40 that are configured in a Ravigneaux type coaxially. The rotation of the input shaft 19 is changed and output from the output gear 24.

  Specifically, the automatic transmission 18 includes the rotating elements of the first planetary gear device 36, the second planetary gear device 38, and the third planetary gear device 40 (sun gear S1-S3, carrier CA1-CA3, ring gear R1- R3) is directly or indirectly (or selectively) via a hydraulic friction engagement device (clutch C1, C2 and brakes B1, B2, B3) or one-way clutch (one-way clutch) F1. The parts are connected to each other, or connected to the input shaft 19, the case 20, or the output gear 24. Then, according to the disengagement control of each of the clutches C1, C2 and the brakes B1, B2, B3, according to the driver's accelerator operation, vehicle speed V, etc., as shown in the engagement operation table of FIG. Thus, each reverse gear (each gear) is established. In FIG. 3, “1st” to “6th” are the first to sixth gears as the forward gear, “R” is the reverse gear, and “N” is the neutral where no gear is established. Means state. The engagement operation table of FIG. 3 summarizes the relationship between the above gear stages and the operation states of the clutches C1 and C2 and the brakes B1, B2 and B3. Engagement only when the engine is braked, and the blank indicates release. Since the one-way clutch F1 is provided in parallel to the brake B2 that establishes the first speed gear stage “1st”, it is not always necessary to engage the brake B2 when starting (acceleration).

  The clutches C1, C2 and the brakes B1, B2, B3 (hereinafter simply referred to as the clutch C, the brake B, or the engagement device unless otherwise distinguished) are hydraulic pressures often used in known vehicular automatic transmissions. This type of friction clutch is composed of a wet multi-plate clutch and brake pressed by a hydraulic actuator, a band brake tightened by a hydraulic actuator, and the like. In the clutch C and the brake B configured in this way, the torque capacity, that is, the engagement force is continuously changed, for example, by excitation, de-excitation, and current control of the linear solenoid valves SL1-SL5 and the like in the hydraulic control circuit 100. Thus, the respective engagement and release states are switched, and the transient engagement hydraulic pressure at the time of engagement and release is controlled.

  Returning to FIG. 1, the vehicle 10 is provided with an electronic control device 80 including a control device of the power transmission device 12 that performs lock-up slip control (slip control) for slip-engaging the lock-up clutch 34 when the vehicle travels, for example. Yes. The electronic control unit 80 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like, for example. The CPU uses a temporary storage function of the RAM and stores a program stored in the ROM in advance. Various control of the vehicle 10 is executed by performing signal processing according to the above. For example, the electronic control unit 80 performs output control of the engine 14, shift control of the automatic transmission 18, torque capacity control of the lockup clutch 34, and the like, and engine control for engine control is performed as necessary. The apparatus and the automatic transmission 18 are divided into a hydraulic control apparatus for shift control, a hydraulic control apparatus for hydraulic control of the lockup clutch 34, and the like.

The electronic control unit 80 receives, for example, the turbine rotation speed N _T that is the rotation speed of the turbine shaft of the torque converter 16 detected by the turbine rotation speed sensor 50 (that is, the input rotation speed N _IN that is the rotation speed of the input shaft 19). A signal indicating a hydraulic oil temperature TH _OIL which is a temperature of hydraulic oil (for example, a known ATF) in the hydraulic control circuit 100 detected by the hydraulic oil temperature sensor 52, and a driver detected by the accelerator opening sensor 54. A signal representing the accelerator opening degree Acc, which is an operation amount of the accelerator pedal 56 as an acceleration request amount (driver request amount) for the vehicle 10, an engine speed N, which is a rotation speed of the engine 14 detected by the engine speed sensor 58. Table signal, the cooling water temperature TH _W of the engine 14 detected by a coolant temperature sensor 60 that represents the _E Signal, a signal representing the intake air quantity Q _AIR of the engine 14 detected by an intake air amount sensor 62, a signal representing the throttle valve opening theta _TH is a degree of opening of the electronic throttle valve detected by the throttle valve opening sensor 64 , A signal representing the output rotation speed N _OUT which is the rotation speed of the output gear 24 corresponding to the vehicle speed V detected by the vehicle speed sensor 66, and the foot brake which is a service brake detected by the brake switch 68 being operated (during a stepping operation) ) Indicating the operation (brake on) B _ON of the foot brake pedal 70, the lever position of the shift lever 74 detected by the lever position sensor 72 such as “P”, “R”, “N”, “D”, etc. (Operating position, shift position) Signals representing _PSH and the like are supplied.

Further, the electronic control unit 80, drive signals as an engine output control command signal S _E for the output control of the engine 14, for example, to a throttle actuator for controlling the opening and closing of the electronic throttle valve in accordance with the accelerator opening Acc Also, an injection signal for controlling the fuel injection amount injected from the fuel injection device, an ignition timing signal for controlling the ignition timing of the engine 14 by the igniter, and the like are output. Further, as the hydraulic pressure control command signal S _P output for shift control of the automatic transmission 18, for example, excitation of the linear solenoid valves SL1-SL5 of the hydraulic control circuit 100 to switch the gear stage of the automatic transmission 18, the non-energized such Oil pressure command to the linear solenoid valve SLT for regulating the pressure of the valve command signal (hydraulic command signal, oil pressure command value, drive signal) for controlling the pressure, the first line oil pressure P _L1 , the second line oil pressure P _L2, etc. A signal or the like is output to the hydraulic control circuit 100. Further, as a lock-up control command signal S _L for controlling engagement / release of the lock-up clutch 34 and slip amount (differential rotational speed) N _S (= N _E −N _T ), for example, in the hydraulic control circuit 100 A hydraulic pressure command signal for driving the linear solenoid valve SLU and the solenoid valve SL (see FIG. 4) included in the hydraulic pressure control circuit 100 is output to the hydraulic pressure control circuit 100.

FIG. 4 is a diagram illustrating a main part of the hydraulic control circuit related to the operation control of the lockup clutch 34 in the hydraulic control circuit 100. 4, the hydraulic control circuit 100, SL instruction (SL command) signal S _SL switching solenoid is turns on and off operation to generate a switching signal pressure P _SL by on-off signal corresponding to supplied from the electronic control unit 80 A valve SL, a lockup relay valve 102 for switching between a released state and an engaged or slipped state of the lockup clutch 34; a lockup clutch pressure command value (LU clutch pressure command value; and the linear solenoid valve SLU for slip control for outputting a signal pressure _{P SLU} corresponding to the drive current _{I SLU} corresponding to SLU command _{pressure) S SLU,} the lock-up clutch 34 is set to the engaged or slipping state by the lock-up relay valve 102 lock-up clutch in accordance with the signal pressure P _SLU when that 4 of the differential rotation speed N _S of the control or lock-up clutch 34 engaged thereby for (i.e. for switching the operating state of the lockup clutch 34 in the range of the slip state to the lock-up on) the lock-up control valve 104 It has.

As shown in FIG. 4, the lock-up relay valve 102 has a spool 106 for switching the connection state, the release-side position (off the lock-up clutch 34 and a released state in response to the switching signal pressure P _SL Side position) and an engagement side position (on-side position) where the lockup clutch 34 is engaged or slipped. 4 shows a state in which the spool valve element 106 is positioned at the off-side position (OFF) where the lock-up clutch 34 is released on the left side from the center line, and the right side from the center line is engaged or A state in which the spool valve element 106 is positioned at the ON side position (ON) in the slip state is shown.

  The lockup control valve 104 includes a spool valve element 108 for switching the connection state, and is switched between a slip (SLIP) side position and a complete engagement (ON) side position. 4 shows a state in which the spool valve element 108 is positioned at the slip (SLIP) side position on the left side of the center line, and the spool valve element is positioned on the right side of the center line at the fully engaged (ON) side position. 108 shows a state in which it is located.

The slip control linear solenoid valve SLU outputs a signal pressure P _SLU for controlling the engagement pressure at the time of engagement or slip engagement of the lockup clutch 34 in accordance with a command from the electronic control unit 80. . For example, the slip control linear solenoid valve SLU is a solenoid control valve that the modulator pressure P _M to pressure regulated by the hydraulic control circuit 100 and source pressure and outputs a signal pressure P _SLU under reduced pressure the modulator pressure P _M Thus, a signal pressure P _SLU proportional to the drive current (excitation current) I _SLU corresponding to the LU clutch pressure command value S _SLU supplied from the electronic control unit 80 is generated.

Further, switching the solenoid valve SL is for outputting a predetermined switching signal pressure P _SL accordance SL command signal (OFF signal) S _SL from the electronic control unit 80. For example, switching the solenoid valve SL is locking the non-energized state (off state), the switching signal pressure P _SL is a drain pressure, the in energized state (ON state) switching signal pressure P _SL as a modulator pressure P _M By acting on a predetermined oil chamber of the up-relay valve 102, the spool valve element 106 of the lock-up relay valve 102 is moved to the ON position (ON) in the engaged state.

With the hydraulic control circuit 100 configured as described above, the supply state of the operating oil pressure to the engagement side oil chamber 16on and the release side oil chamber 16off is switched, and the operation state of the lockup clutch 34 is switched. First, the case where the lock-up clutch 34 is in the slip state or lock-up on will be described. In the lock-up relay valve 102, the spool 106 by switching the solenoid valve SL is energized to the on-side position, the second line pressure P _L2 is supplied to the engagement-side oil chamber 16On. The second line pressure _{P L2} supplied to the engagement-side oil chamber 16on becomes pressure _{P ON.} At the same time, the hydraulic pressure P _OFF in the release-side oil chamber 16off is adjusted by the lock-up control valve 104 (that is, the differential pressure ΔP (= P _ON -P _OFF ), that is, the engagement pressure is adjusted by the lock-up control valve 104). The operation state of the lock-up clutch 34 is switched in the range from the slip state to the lock-up on.

Specifically, when the spool valve element 106 of the lockup relay valve 102 is biased to the engaged (ON) side position, that is, when the lockup clutch 34 is switched to the engaged or slipped state, When the spool valve element 108 in the lock-up control valve 104 is a slip (sLIP) side position, the second line pressure _{P L2} is supplied to the release side oil chamber 16Off. The flow rate of the hydraulic oil at this time is controlled by the signal pressure _PSLU . That is, in a state where the spool valve element 108 is in the slip (SLIP) side position, the differential pressure ΔP is controlled by the signal pressure P _SLU of the linear solenoid valve SLU for slip control, and the slip state of the lockup clutch 34 is controlled. The Further, when the spool valve element 106 of the lockup relay valve 102 is urged to the ON position, the spool valve element 108 is urged to the fully engaged (ON) position in the lockup control valve 104. , it is to release oil chamber 16off not supplied second line pressure P _L2, operating oil from the release-side oil chamber 16off is discharged from the drain port EX of the lockup control valve 104. As a result, the differential pressure ΔP is maximized and the lockup clutch 34 is fully engaged.

On the other hand, in the lock-up relay valve 102 is not supplied with switching signal pressure P _SL, the spool 106 is brought into position to off-side position, the second line pressure P _L2 is supplied to the release side oil chamber 16off . Then, the hydraulic oil discharged through the engagement side oil chamber 16on is supplied to the oil cooler via the lockup relay valve 102 and cooled. That is, in a state where the spool valve element 106 of the lockup relay valve 102 is positioned to the off-side position, the lockup clutch 34 is released, and the slip control linear solenoid valve SLU to the lockup control valve 104 are turned off. No slip or engagement control is performed. In other words, even when the signal pressure P _SLU output from the slip control linear solenoid valve SLU is changed, the spool valve element 106 of the lockup relay valve 102 is positioned to the off-side position. As far as this is concerned, the change is not reflected in the engaged state (differential pressure ΔP) of the lockup clutch 34.

Incidentally, the differential pressure ΔP, which is controlled by the signal pressure P _SLU of the slip control linear solenoid valve SLU is a hydraulic value representing the engaging or releasing state of the lock-up clutch 34, the lock-up clutch pressure P _LU in this embodiment And Further, the lock-up clutch pressure P _LU is also the oil pressure value corresponding to the torque capacity (the lock-up clutch torque) T _LU of differential rotation speed N _S and the lock-up clutch 34. The LU clutch pressure command value S _SLU and the signal pressure P _SLU of the slip control linear solenoid valve SLU are hydraulic pressure command values of the lockup clutch pressure P _LU .

FIG. 5 is a functional block diagram for explaining the main part of the control function by the electronic control unit 80. In FIG. 5, the engine output control unit, that is, the engine output control means 82 controls the fuel injection amount by the fuel injection device for controlling the fuel injection amount in addition to controlling the opening and closing of the electronic throttle valve by the throttle actuator, for example, for throttle control. and outputs an engine output control command signal S _E for controlling the ignition device such as an igniter for ignition timing control. For example, the engine output control means 82, the estimated value of the engine rotational speed N _E and engine torque T _E and the throttle valve opening theta _TH as a parameter (hereinafter estimated engine torque) in advance experimentally determined with T E _'storage closing the electronic throttle valve so that the throttle valve opening theta _TH which target engine torque T _E ^* obtained based on the actual engine rotational speed N _E from been example relationship as shown in FIG. 6 (engine torque map) In addition to controlling, the fuel injection amount by the fuel injection device is controlled to control an ignition device such as an igniter. The target engine torque T _E ^* is determined by the electronic control unit 80 so as to increase as the accelerator opening Acc increases, for example, based on the accelerator opening Acc corresponding to the acceleration request amount. Corresponds to torque. In the engine torque map as shown in FIG. 6, parameters corresponding to other engine loads such as the intake air amount Q _AIR may be used _instead of the throttle valve opening θ _TH .

The shift control unit, that is, the shift control means 84 is stored in advance, for example, having an upshift line for determining an upshift and a downshift line for determining a downshift using the vehicle speed V and the accelerator opening Acc as variables. Based on the known relationship (shift map, shift map), the shift determination is made based on the vehicle state indicated by the actual vehicle speed V and the accelerator opening Acc, and it is determined whether or not the shift of the automatic transmission 18 should be executed. . Then, the shift control means 84 determines a gear stage to be shifted in the automatic transmission 18 and outputs a shift command for executing the automatic shift control of the automatic transmission 18 so that the determined gear stage is obtained. For example, the shift control means 84 is a hydraulic pressure that engages and / or releases the hydraulic friction engagement device involved in the shift of the automatic transmission 18 so that the gear stage is achieved according to the engagement operation table shown in FIG. control command signal to output the (shift output command value) S _P to the hydraulic control circuit 100. The hydraulic control circuit 100, as in the current gear stage of the automatic or as shifting of the automatic transmission 18 is executed transmission 18 is maintained in accordance with the oil pressure control command signal S _P, the hydraulic control circuit 100 The linear solenoid valves SL1-SL5 are actuated to actuate each hydraulic actuator of the hydraulic friction engagement device involved in the formation (formation) of the gear stage.

The lock-up clutch control unit, that is, the lock-up clutch control means 86 has, for example, a prestored relationship having a lock-up off region, a lock-up slip region, and a lock-up on region with the vehicle speed V and the throttle valve opening θ _TH as variables. Based on the vehicle state indicated by the actual vehicle speed V and the throttle valve opening _θTH , the switching of the operation state of the lockup clutch 34 is controlled from the map and the lockup region diagram). For example, the lock-up clutch control means 86 determines whether the lock-up off region, the lock-up slip region, or the lock-up on region from the lock-up region diagram based on the actual vehicle state, switching of the lock-up off of the clutch 34, or outputs a lockup control command signal S _L for the lock-up slip state to switching to lock-up on to the hydraulic control circuit 100. The lock-up clutch control unit 86 determines that a lock-up slip region, sequentially calculates an actual differential rotation speed N _S of the lock-up clutch _{34 (= N E -N T)} , its actual rotational difference speed N _S outputs a lockup control command signal S _L for controlling the differential pressure ΔP so that the target rotational speed difference N _S ^* to the hydraulic control circuit 100. For example, at a certain gear stage, in a relatively high vehicle speed range, the lockup clutch 34 is locked up and the pump impeller 16p and the turbine impeller 16t are directly connected to each other, thereby causing slip loss (internal loss) of the torque converter 16. To improve fuel economy. Further, in some gear, at relatively low to medium speed region, the predetermined minute slip corresponding to example 50rpm~100rpm about target differential rotation speed N _S ^* between the pump impeller 16p and the turbine impeller 16t By performing slip control (lock-up slip control) that is applied and slip-engaged, the lock-up operation region is expanded, the transmission efficiency of the torque converter 16 is improved, and the fuel efficiency is improved.

The hydraulic control circuit 100 actuates the lock-up control command signal S switching solenoid valve SL as release of the lockup clutch 34 and the slipping state to the fully engaged is switched in accordance with _L from the lock-up clutch control unit 86 The valve position of the lockup relay valve 102 is switched between a release side (OFF) position and an engagement side (ON) position. The hydraulic control circuit 100, the lock-up clutch torque T _LU at the slip state to full engagement of the lock-up clutch 34 according to the lock-up control command signal S _L from the lock-up clutch control unit 86 via the lock-up control valve 104 It is the way to control the differential speed N _S of actuating the slip control linear solenoid valve SLU engaging the lockup clutch 34 or lock-up clutch 34 increases or decreases Te.

In addition, the lock-up clutch control means 86 is used to improve fuel efficiency by utilizing a low-rotation high-torque region with relatively good engine combustion efficiency when the vehicle starts, for example, when the accelerator is on (depressing the accelerator pedal 56). performs an increase in the engine rotational speed N _E (racing) lock-up clutch 34 slip-engaged to start-time lock-up slip control so as to suppress (start-time slip control). In this starting slip control, for example, when a predetermined starting slip control start condition set in advance is satisfied, the fuel consumption and the power performance are made compatible in accordance with the accelerator opening Acc as the acceleration request amount for the vehicle 10. suppress the rise blows engine rotational speed N _E in to suppress fuel consumption. In the vehicle state to perform such start-time slip control, the immediately accelerator-on in a state where the lock-up clutch 34 is released (e.g., immediately after vehicle start), since a transition period which rises the engine rotation speed N _E differential speed _{N S (= N E -N T} ) difficult to control. Therefore, in this start-time slip control, for example, to suppress the rise blows engine rotational speed N _E, the open-loop control (open to set a certain LU clutch pressure command value S _SLU corresponding to the accelerator opening Acc Control, feedforward control). Then, for example, when the vehicle state is determined to be in the lock-up slip region, as described above, to perform the slip control for slip-engaged lockup clutch 34 as the differential rotation speed N _S is the target value (this Slip control by feedback control is referred to as steady-state lockup slip control (steady-state slip control). Alternatively, for example, differential speed during starting when the slip control N _S is determined to become within a predetermined differential rotation speed N _{S ',} continuously steady slip control following the start-time slip control (acceleration slip control ). The actual value in this steady state slip control, for example, the differential rotation speed _{N S} (actual differential rotation speed _{N S)} and a target value (target differential rotation speed _N ^{S *)} deviation between ^{_{ΔN S (= N S * -N}} S) Based on the feedback control, the closed loop feedback control for sequentially setting the LU clutch pressure command value S _SLU is executed.

As the predetermined start-time slip control start condition, for example, a signal indicating whether the lever position P _SH is the “D” position, whether the brake is off, ie, the brake on B _ON is not input. Whether the hydraulic oil temperature TH _OIL is within a predetermined temperature range, for example, a temperature range from the temperature after completion of warm-up to an oil temperature that is not determined to be a high oil temperature, Whether or not the gear is in a gear shift, whether or not the vehicle 10 is determined to be stopped, whether or not the accelerator is on, and whether or not the vehicle is in the start-up lock-up slip region, that is, the accelerator opening Whether or not the accelerator is turned on so that Acc becomes a predetermined low opening degree is established.

It should be noted that the above-described slip control at the time of start is such that the lock-up clutch 34 is directed to be engaged so as to prevent the engine rotational speed _NE from temporarily rising as the accelerator is turned on when the vehicle is started with the accelerator turned on. Control for slip engagement. Therefore, the start-time slip control is performed in an accelerator-on vehicle in which, for example, the accelerator opening Acc is relatively low in order to make it difficult for the driver to feel uncomfortable in the vehicle acceleration feeling with respect to the depression of the accelerator pedal 56. It is desirable to be executed at the start. Therefore, in the lockup region diagram used for determining whether or not the vehicle is in the start-up lockup slip region as one of the predetermined start-up slip control start conditions, for example, the throttle valve opening _θTH is The start-up lockup slip region is set in a relatively low opening region. In this embodiment, the lock-up slip region for determining execution of the steady-state slip control is referred to as a steady-state lock-up slip region in order to distinguish it from the start-up lock-up slip region. The lock-up slip region at the start of the vehicle, for example, a region that is set in consideration of the fuel efficiency by suppressing racing of the engine rotational speed N _E, the lock-up slip region during the steady state, for example, driver This is a region that is set in consideration of the performance and the booming noise (for example, NVH (noise / vibration / riding comfort) performance). Further, in the steady-state slip control, what is executed at the time of acceleration-on acceleration traveling may be distinguished as acceleration slip control, and what is executed at the time of accelerator-off deceleration traveling may be distinguished as deceleration slip control.

For example, when a predetermined steady-state slip control start condition set in advance is satisfied during execution of the start-time slip control, the start-time slip control shifts to the normal-time slip control. The start-time slip control and the steady-state slip control are both slip control, but can be regarded as independent controls since the setting method of the LU clutch pressure command value S _SLU is completely different.

FIG. 7 is a diagram illustrating an example of the LU clutch pressure command value S _SLU that is set when the start-time slip control and the steady-state slip control are executed. In FIG. 7, as the LU clutch pressure command value S _SLU in the starting slip control, first, output of a clutch pressure command value for first fill (rapid filling) is started (at time t1), and then the engine rotational speed _NE Is maintained at a constant clutch pressure command value S _LUFF in the feedforward control for suppressing the blow-up (from time t2 to time t3). When the time prescribed constant slip control starting condition is satisfied (t3 time point), the clutch pressure command value _{S LUSW} which gradually increases the clutch pressure command value _{S LUFB} in the feedback control from the clutch pressure command value _{S Luff} is output (t3 point to time point t4), the clutch pressure command value _{S LUFB} of feedback control for matching the actual differential rotation speed _{N S} target differential rotation speed _N ^{S *} is sequentially set (t4 after the time).

Certain clutch pressure command value S _Luff in the feed-forward control, for example, so as to suppress the engine rotational speed N _E blows up of, are set according to the accelerator opening Acc or the throttle valve opening theta _TH like. That is, as more i.e. the throttle valve opening theta _TH is larger accelerator opening Acc is large, large engine torque T _E, it becomes steeper Also revving of the engine 14. Therefore, by increasing the fast lock-up clutch torque T _LU than enough accelerator opening Acc is larger from the viewpoint of easily suppressing the engine rotational speed N _E, for example, as the accelerator opening Acc is large, the clutch pressure command value S The LU clutch pressure command value S _SLU in the starting slip control is set so as to increase the _LUFF . In place of the accelerator opening Acc, the estimated engine torque T _E ′ calculated from the throttle valve opening θ _TH , the intake air amount Q _AIR , the fuel injection amount, the throttle valve opening θ _TH or the intake air amount Q _AIR, etc. Needless to say, various modes such as the use of are possible.

The predetermined steady-state slip control start condition is, for example, whether or not there is a vehicle state in the steady-state lockup slip region in the lockup region diagram. In particular, as the predetermined stationary time slip control starting conditions when a time of transition from the start-time slip control, for example, feed to increase in the engine rotational speed N _E during the start-time slip control is suppressed to some extent experimentally determined in advance is the predetermined difference is set in rotation speed N _{S 'actual} differential rotation speed N _S below the drop for that is determined to be performed appropriately slip control be switched to the feedback control from the forward control Or not.

Thus, the lock-up clutch control means 86, when the predetermined start-time slip control starting condition is satisfied, a certain clutch pressure based on the accelerator opening Acc to suppress the rise blows engine rotational speed N _E A command value S _LUFF is set, and a slip engagement command for controlling the lock-up clutch pressure P _LU of the lock-up clutch 34 by driving the slip control linear solenoid valve SLU by the clutch pressure command value S _LUFF is provided in the hydraulic control circuit 100. Feed-forward control to be output to is executed, and the lock-up clutch 34 is slip-engaged.

By the way, in the slip control linear solenoid valve SLU, the characteristic (I / P characteristic) of the signal pressure P _SLU corresponding to the drive current I _SLU corresponding to the LU clutch pressure command value (SLU command pressure) S _SLU is, for example, the initial quality. There is a hardware variation of ± several tens [kPa], and a corresponding variation occurs in the lockup clutch torque T _LU with respect to the LU clutch pressure command value S _SLU . For this reason, in the slip control linear solenoid valve SLU whose I / P characteristic has a variation of + several tens [kPa], the clutch pressure command value S _LUFF as the LU clutch pressure command value S _SLU in the slip control at the start of The lock-up clutch torque T _LU at the time of vehicle start transition becomes excessive (that is, the lock-up clutch 34 is grasped too much immediately after the vehicle starts), and torque swing or shock may occur (see FIG. 13). On the other hand, by correcting the lock-up clutch pressure P _LU (LU clutch pressure command value S _SLU (clutch pressure command value S _LUFF ) in the slip control at start) by learning, hardware variations and secular changes It can be considered that However, when starting the vehicle, there are many variation factors depending on hardware (for example, engine torque stability at the time of start-up, friction coefficient change accompanying change in slip speed of the lockup clutch 34, play of the accelerator pedal 56, etc.). Then, it is difficult to detect the variation of the lockup clutch torque T _LU start of the vehicle transient stably likely to be stably difficult to learn the lockup clutch pressure P _LU at starting time of slip control is there. The present embodiment proposes a method capable of stably learning the lock-up clutch pressure _PLU in the slip control at the start even when the vehicle starts with many hardware-dependent variation factors.

Specifically, in this embodiment, the actual engine rotational speed N _E when the starting time of the slip control in the differential rotation speed N _S of the lock-up clutch 34 is maximum _(maximum time of actual engine rotational speed N _E max) is , the estimated engine torque T _E when the differential rotation speed N _S is maximum '(maximum time estimated engine torque T _E' max) differential rotation speed increases in accordance into N _S is the maximum target engine speed N _E when ^* If it is lower than (maximum target engine speed N _E ^* max), it is determined that the lock-up clutch torque T _LU is excessive (that is, it is determined that the lock-up clutch 34 is excessively gripped) and the vehicle starts. The lockup clutch pressure P _LU (the clutch pressure command value S _LUFF is also agreed) in the hour slip control is corrected to the reduced pressure side by learning. For example, the maximum time of the actual engine rotational speed N _E max when the differential rotation speed N _S of the lock-up clutch 34 is maximum at the starting time of the slip control in, the differential rotation speed N _S is the maximum engine rotational speed N _E when the ( maximum when the engine rotational speed N _E max) and experimentally determined in advance was lockup clutch torque T _LU plethora detection of the engine torque T _E (determined) the target value for (i.e. gripping too far lockup clutch 34 calculated based on the maximum time estimated engine torque T _{E 'max} when the relationship for example, as shown in FIG. 8 has a target line a (map) the differential rotation speed N _S is the maximum as a target value) for determining the maximum time target engine is the differential speed N _S is compared with the maximum time target engine rotational speed N _E ^* max at the maximum, the direction of maximum when the actual engine rotational speed N _E max When rolling speed N _E ^* less than max corrects the depressurization by learning lockup clutch pressure P _LU at starting time of the slip control. Further, on the contrary, when the direction of the maximum time of the actual engine rotational speed N _E max is higher than the maximum time target engine rotational speed N _E ^* max, it is determined that the lockup clutch torque T _LU is not excessive, at the start The lockup clutch pressure _PLU in the slip control is corrected to the pressure increasing side by learning.

The maximum target engine speed N _E ^* max is made as much as possible in order to improve fuel efficiency within a range where deterioration of drivability due to going to the lockup clutch 34 during the start slip control is allowed. differential rotation speed N _S obtained experimentally in advance as a reduced (suppressed) engine rotational speed N _E is the maximum ideal engine rotational speed when the. The relationship shown in FIG. 8 is a map that is experimentally obtained and stored in advance based on such a viewpoint. A goal line is a series of ideal engine rotational speed differential rotation speed N _S corresponds to the engine torque T _E when the maximum in relation to FIG 8, the maximum difference revolution speed N _S is the relationship of FIG. 8 5 is an ideal engine rotation speed map that defines an ideal engine rotation speed at the time of

Further, when the differential rotation speed N _S is maximum, the slip control end time from the lapse of the slip control initial time TSL as a first predetermined time after the start of the start-time slip control as the second predetermined time TSH There is determined in advance sought within a certain predetermined time period TS for See phenomenon of differential rotation speed N _S at the starting time of the slip control in stored until the end. This is precisely the Phenomenon of the differential rotation speed N _S at the starting time of the slip control in that it becomes smaller with the slip engagement of the vehicle at the time of start becomes larger with the engine racing by the accelerator-on and lock-up clutch 34 This is to capture. In other words, this is because the phenomenon of engine blowing is limited to that caused by slip control at start. For example, in the initial stage of the start-time slip control, since the operation of the accelerator pedal 56 may not rise blow firmly the engine rotational speed N _E unstable, the engine rotational speed N _E is then fully blown up differential speed N _S in a state wishes to determine when the maximum. Moreover, descending turbine shaft rotation speed N _T with increasing vehicle speed V is increased by the brake off at slope, since the differential rotation speed N _S of the initial stage of the start-time slip control is likely to be determined to a maximum, the differential rotation speed N _S in the state from the firmly blow up the engine rotation speed N _E wants to determine when to be a maximum. For this reason, until the slip control initial time TSL has elapsed after the start of the start-time slip control, differential speed N _S is not to determine when the maximum. Further, when a long period has elapsed since the beginning of the start-time slip control has passed, so the differential rotation speed N _S by other factors accelerator release operation or hill drive or the like is likely to be determined to a maximum, the starting time of the slip control I want to limit it to the factor. For this reason, only the differential rotation speed N _S to slip control end time TSH has elapsed after the start of the start-time slip control is not to determine when the maximum.

Here, by the differential rotation speed N _S of the lock-up clutch 34 is used and the engine torque T _E and the engine speed N _E when the maximum is too large lock-up clutch torque T _LU in starting time of the slip control The reason for adopting the control of determining (detecting) whether or not will be described below.

Generally, equilibrium equation of the torque converter 16, the engine torque _{T E,} the pump torque _{T P,} the lock-up clutch torque _{T LU,} engine inertia _{I E,} and based on the engine rotational speed _{N E,} the following equation (1) It is expressed as The pump torque T _P, based on the capacity coefficient of the torque converter 16 C and the engine rotational speed N _E, as represented by the following formula (2). Here, when the differential rotation speed N _S of the lock-up clutch 34 is maximized, the differential rotation variation of the engine rotational speed N _E (dN _{E /} dt) is substantially zero, and the inertia term of the following formula (1) Can be ignored. Therefore, the balance equation of the torque converter 16 is expressed by the following equation (3). The capacity coefficient C of the torque converter 16 in the following equation (3) is a function (C = f (e)) of the speed ratio e (= turbine rotational speed N _T / engine rotational speed N _E ) of the torque converter 16, As shown in FIG. 9 showing the operational characteristic diagram of the torque converter 16, it becomes a substantially constant value (constant CONST) at the start transient when the engine speed _NE is relatively large with respect to the turbine speed _NT . Then, the following equation (3), the general quadratic function (y = ax ^{2 +} c) and can be seen, the engine torque T _E and the engine speed N _E when the differential rotation speed N _S is maximum As shown in the ideal engine rotation speed map of FIG. 8, a region where the lockup clutch torque _TLU is excessive (that is, a region where the lockup clutch 34 is excessively gripped) is experimentally set in advance. Can do it. Therefore, by using the engine torque T _E and the engine speed N _E when the differential rotation speed N _S is maximized, even during high starting transient hardware-dependent variation element, the lock-up clutch torque T _LU and variation of the engine torque T _E to be able to detect stable, stable (appropriately) the lock-up clutch pressure P _LU at starting time of the slip control can be learned. The engine inertia _IE is a constant (experimental value) obtained and stored, for example, in design or experimentally in advance.
T _E = T _P + T _LU + I _E × (dN _E / dt) (1)
T _P = C × N _E ² (2)
T _E = C × N _E ² + T _LU (3)

  More specifically, returning to FIG. 5, the start slip control execution determination unit, that is, the start slip control execution determination means 88 determines whether or not the start slip control by the lockup clutch control means 86 is being executed. Determine.

The differential rotation speed maximum determination unit, that is, the differential rotation speed maximum determination means 90 starts the start slip control when the start slip control execution determination means 88 determines that the start slip control is being executed. control time from the when within a predetermined time period TS from the slip control initial time TSL elapsed until the slip control end time TSH elapsed, determines whether it is the differential rotation speed N _S of the lock-up clutch 34 is maximized. For example, determining whether a change in the differential rotation speed _{N S (d (N S /} dt)) is the differential rotation speed N _S based on whether a zero or negative value is maximized within a predetermined time period TS To do.

Maximum target value calculation portion, that is the maximum target value calculation means 92, when the differential rotation speed N _S is determined to become maximum by differential speed up determining means 90, for example, from the engine torque map shown in FIG. 6 The maximum estimated engine torque T _E 'max is calculated based on the maximum actual engine speed N _E max and the actual throttle valve opening θ _TH at that time. Then, the maximum target value calculation means 92, for example, the maximum time target engine rotational speed from the ideal engine rotational speed map shown in FIG 8 on the basis of the maximum time estimated engine torque T _{E 'max} calculated above N _E ^* max ( differential rotation speed N _S is calculated ideal engine speed) at the maximum.

The maximum rotation speed comparison unit, that is, the maximum rotation speed comparison means 94 compares the maximum actual engine rotation speed N _E max with the maximum target engine rotation speed N _E ^* max. For example, the maximum rotation speed comparison means 94 determines whether or not the maximum target engine rotation speed N _E ^* max is higher than the maximum actual engine rotation speed N _E max. In other words, the maximum time of rotation speed comparing unit 94, by the maximum time target engine rotational speed N _E ^* max to determine whether higher than the maximum time of the actual engine rotational speed N _E max, the lock-up clutch torque T _LU is excessive (That is, whether or not the lock-up clutch 34 is grasped too much) is determined (detected). That is, to detect the variation of the lockup clutch torque T _LU.

The learning control unit, that is, the learning control unit 96, determines that the maximum target engine rotation speed _NE ^* max is higher by the maximum rotation speed comparison unit 94 (that is, the lockup clutch torque _TLU is excessive). If it is determined), the lock-up clutch pressure P _LU (the clutch pressure command value S _LUFF is also agreed) in the start slip control is corrected to a reduced pressure side by a predetermined correction amount by learning. For example, the learning control means 96 is a clutch pressure command value S _LUFF (corrected by the previous learning, which is a current learning value stored in a storage device (memory) such as a known EEPROM provided in the electronic control device 80. When not yet learned, the previously stored clutch pressure command value S _LUFF ) is updated to the reduced pressure side by a predetermined correction amount. On the other hand, the learning control means 96, when if the direction of the maximum time of the actual engine rotational speed N _E max is determined to be high (i.e. the lock-up clutch torque T _LU is determined not to be excessive by the maximum time of rotation speed comparison means 94 ), The lock-up clutch pressure _PLU in the starting slip control is corrected to the pressure increasing side by a predetermined correction amount by learning. For example, the learning control means 96 updates the current learning value to the pressure increasing side by a predetermined correction amount. Thus, in the learning control of the present embodiment, learning is executed with the learning value (lock-up clutch pressure P _LU ) after the previous learning as the base pressure (basic value), and the base pressure is updated. That is, the learned value (base pressure) after learning becomes the base pressure for the next learning.

The predetermined correction amount may be a uniform correction amount ΔP _LU obtained by learning that is obtained in advance and stored, or the maximum actual engine speed N _E max and the maximum target engine speed N _E ^* max. May be a correction amount ΔP _LU by learning that increases as the difference ΔN _E max (= | N _E max−N _E ^* max |) increases. FIG. 10 shows a relationship (correction amount map) obtained and stored experimentally in advance between the difference ΔN _E max and the correction amount ΔP _LU by learning, and the correction increases as the difference ΔN _E max increases as shown by the solid line. The amount ΔP _LU is increased. As a result, the lockup clutch pressure _PLU is corrected more appropriately. Further, as indicated by a broken line in FIG. 10, the correction amount ΔP _LU may be increased after the difference ΔN _E max exceeds a predetermined value E. Thereby, the update frequency of the learning value of the lockup clutch pressure _PLU by learning is suppressed. Accordingly, it is possible to prevent the correction of the learning value to the pressure reduction side and the correction of the learning value to the pressure increase side (for example, hunting) in the vicinity where the difference ΔN _E max is zero, or to suppress the learning value. The physical durability of the storage device (memory) to be saved is improved. Note that the difference here represents the absolute value of the rotational speed difference.

The correction of the pressure increase side of the lock-up clutch pressure P _LU is made to suppress racing of the engine rotational speed N _E, but contribute to improving fuel efficiency tends to deteriorate drivability. Therefore, towards the maximum when the actual engine rotational speed N _E max is high, the repetition determining, lockup clutch pressure when the can determine that the lock-up clutch torque T _LU during vehicle start transient is not reliably sufficient it is desirable to correct the P _LU to increase pressure side. Therefore, in view of emphasizing drivability by carefully corrected to increase pressure side of the lock-up clutch pressure P _LU, learning control means 96, the maximum time of the actual engine rotational speed N by the maximum time of rotation speed comparison means 94 _When it is determined that _E max is higher for a predetermined number of times, the lock-up clutch pressure _PLU in the starting slip control is corrected to the pressure increasing side by a predetermined correction amount by learning. Also good. The predetermined number of times is, for example, a torque shortage determination value that is experimentally obtained and stored in advance so that it can be determined that the lockup clutch torque _TLU is not sufficient.

FIG. 11 is a flowchart for explaining a control operation for stably learning the lock-up clutch pressure _PLU in the slip control at the start even when the vehicle is starting, that is, the main part of the control operation of the electronic control unit 80, For example, it is repeatedly executed with an extremely short cycle time of about several milliseconds to several tens of milliseconds. FIG. 12 is a time chart corresponding to the control operation of FIG.

In FIG. 11, first, in S10 corresponding to the starting slip control execution determining means 88, it is determined whether, for example, the starting slip control is being executed. If the determination in S10 is negative, this routine is terminated, but if the determination is affirmative (after time t1 in FIG. 12), in S20 corresponding to the differential rotational speed maximum determination means 90, for example, start slip control is started. when the control time is within a predetermined time period TS from the slip control initial time TSL elapsed until the slip control end time TSH elapsed from the change in the differential rotation speed _{N S (d (N S /} dt)) is zero or negative value differential rotation speed N _S of the lock-up clutch 34 based on whether a is determined whether the maximum (t2 time to time t4 in FIG. 12). If the determination in S20 is negative, this routine is terminated. If the determination is affirmative, in S30 corresponding to the maximum target value calculation means 92, for example, the actual engine speed is determined from the engine torque map as shown in FIG. Based on the speed N _E (that is, the maximum actual engine rotational speed N _E max) and the actual throttle valve opening θ _TH , the estimated engine torque T _E ′ (that is, the maximum estimated engine torque T _E ′ max) is calculated. The ideal case up time target engine rotational speed N _E ^* max (differential rotation speed N _S is maximum, for example, from the ideal engine rotational speed map shown in FIG 8 on the basis of the maximum time estimated engine torque T _{E 'max} Engine speed) is calculated (at time t3 in FIG. 12). Next, in S40 corresponding to the maximum rotation speed comparison means 94, for example, it is determined whether or not the maximum target engine rotation speed N _E ^* max calculated in S30 is higher than the maximum actual engine rotation speed N _E max. Is done. In Step S50 affirmative has been locked up clutch torque T _LU determination in S40 is the case is too large, corresponding to the learning control unit 96, the memory lock-up clutch pressure P _LU example the electronic control device 80 at the starting time of the slip control is provided The clutch pressure command value S _{LUFF that} has been corrected by the previous learning, which is the stored current learning value, is updated to the reduced pressure side by a predetermined correction amount by learning. On the other hand, in S60 if the corresponding to the learning control means 96 for the lockup clutch torque T _LU determination is negative the S40 is insufficient, the learning value of the lock-up clutch pressure P _LU example the current at the starting time of the slip control is The learning is updated to the pressure increase side by a predetermined correction amount.

Note that S60 may be executed when the determination of S40 is continuously denied a predetermined number of times. As the predetermined correction amount, a uniform correction amount ΔP _LU may be used, or a correction amount ΔP _LU calculated based on the difference ΔN _E max from the correction amount map as shown in FIG. May be. Also, different correction amounts ΔP _LU may be used in S50 and S60. For example, the uniform correction amount ΔP _LU itself is different, the correction amount map itself is different, or one of the uniform correction amounts ΔP _LU is used and the other is a correction calculated from the correction amount map. An amount ΔP _LU may be used. In S50, a correction amount map as shown by the solid line in FIG. 10 is used, and in S60, a correction amount map having a hysteresis region (predetermined value E) as shown by the broken line in FIG. 10 is used. It may be used.

As described above, according to this embodiment, the maximum time of the actual engine rotational speed N _E max when the differential rotation speed N _S of the lock-up clutch 34 in the start-time slip control in is maximum, the difference rotation speed N _S When it is lower than the maximum target engine speed N _E ^* max that increases in accordance with the maximum estimated engine torque T _E 'max at the maximum, it is determined that the lockup clutch torque T _LU is excessive, the lock-up clutch pressure P _LU at starting time of the slip control is corrected to depressurization by learning, when the differential rotation speed N _S is the maximum rotational difference change amount of the engine rotational speed N _E (dN _{E /} dt) is or negligible section of the engine inertia I _E in the balance equation of the torque converter 16 is substantially zero (the equation (1)), also function der speed ratio e of the torque converter 16 And the capacity coefficient C of the torque converter 16 is substantially constant state, the variation of the lockup clutch torque T _LU start of the vehicle transient can be detected stably. That is, it is possible to stably determine whether or not the lock-up clutch torque T _LU at the time of vehicle start transition is excessive. Therefore, by the differential rotation speed N _S of the lock-up clutch 34 is used and the engine torque T _E and the engine speed N _E at the maximum, even transient during hard-dependent variation component is large vehicle start, It is possible to stably learn the lock-up clutch pressure _PLU in the start slip control.

Further, according to this embodiment, when the differential rotation speed N _S is the maximum, previously obtained from has elapsed starting time slip control after the start of the slip control the initial time TSL until after the slip control end time TSH is The difference in rotational speed N during start-up slip control that increases as the engine blows and decreases as the lock-up clutch 34 slips is determined. The occurrence phenomenon of _S can be accurately captured.

Further, according to this embodiment, when the direction of the maximum time of the actual engine rotational speed N _E max is higher than the maximum time target engine rotational speed N _E ^* max determines that the lock-up clutch torque T _LU is not excessive Thus, the lock-up clutch pressure _PLU in the start-time slip control is corrected to the pressure-increasing side by learning, so that the lock-up clutch pressure _PLU in the start-time slip control is stably learned even when the vehicle is in a transient state. be able to.

Further, according to this embodiment, increasing when the case towards the maximum when the actual engine rotational speed N _E max is high is determined by the predetermined number of times continuously, by learning the lockup clutch pressure P _LU at starting time of the slip control pressure side is corrected, it is possible to correct the pressure increasing lockup clutch pressure P _LU when able to determine that the lock-up clutch torque T _LU during vehicle start transient is not reliably enough. That is, for that correction to the pressure increase side of the lock-up clutch pressure P _LU is made to suppress racing of the engine rotational speed N _E, but contribute to the fuel efficiency tends to deteriorate drivability , it is possible to focus on drivability by carefully the correction to the pressure increase side of the lock-up clutch pressure P _LU. Further, for example, hunting is suppressed.

Further, according to the present embodiment, the difference ΔN _E max (= | N _E max−N _E ^* max |) between the maximum actual engine speed N _E max and the maximum target engine speed N _E ^* max is large. since increasing the correction amount [Delta] P _LU by the learning enough to become the lockup clutch pressure P _LU is more appropriately corrected by learning.

Further, according to the present embodiment, for example, as shown by the broken line in FIG. 10, the correction amount ΔP _LU is increased after the difference ΔN _E max exceeds the predetermined value E. Therefore, the update frequency of the lockup clutch pressure P _LU by learning is increased. Is suppressed, and the physical durability of the storage device (memory) that stores the learning value is improved.

Further, according to the present embodiment, the maximum target engine speed N _E ^* max is within the range where deterioration of drivability due to going to the lock-up clutch 34 during the start slip control is allowed. since the differential rotation speed N _S obtained experimentally in advance as much as possible reduced (suppressed) engine rotational speed N _E to improve is the maximum ideal engine rotational speed when the vehicle start Even in the transition of time, it is possible to stably learn the lock-up clutch pressure _PLU in the start-time slip control.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the learning control of the above-described embodiment, learning is executed with the learning value after the previous learning as the base pressure (basic value) and the base pressure is updated. Instead, the correction amount for the base pressure may be updated by learning.

In the above-described embodiment, the estimated engine torque T _E ′ is calculated based on the actual engine speed _NE and the actual throttle valve opening θ _TH from the engine torque map as shown in FIG. 6, for example. Not limited to this. For example, the driving force in the driving wheel 32 is calculated from the balance (especially during steady state) of the road load (running resistance) or the vehicle acceleration (particularly during acceleration), and the tire radius of the driving wheel 32 and the rear side of the automatic transmission 18. The reduction gear ratio in the differential gear unit 28, the transmission gear ratio (gear ratio) of the automatic transmission 18, the torque ratio t of the torque converter 16 (= turbine torque T _T / pump torque T _P ), the transmission efficiency of the power transmission device, etc. Therefore, the estimated engine torque T _E ′ may be calculated by converting the driving force into torque on the crankshaft 15. It should be noted that the torque ratio t of the torque converter 16 is obtained from a known relationship (operation characteristic diagram of the torque converter 16) that is experimentally obtained and stored in advance, for example, between the speed ratio e of the torque converter 16 and the torque ratio t. It is calculated based on the speed ratio e.

  In the above-described embodiment, the automatic transmission 18 is an automatic transmission capable of shifting forward 6 speeds and reverse 1 speed. However, the automatic transmission 18 is not particularly limited in the number of shift stages and the internal structure. It is not limited to. That is, the present invention can be applied to any configuration that includes a fluid transmission device having the lock-up clutch 34 and that can perform the slip control at the time of starting. Therefore, the present invention can be applied even to a vehicle equipped with a continuously variable transmission or a so-called DCT (Dual Clutch Transmission).

  In the above-described embodiment, the torque converter 16 provided with the lock-up clutch 34 is used as the fluid transmission device. However, a fluid coupling having no torque amplification function may be used.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

12: Vehicle power transmission device 14: Engine 16: Torque converter (fluid transmission device)
16p: Pump impeller (input rotating member)
16t: Turbine impeller (output rotating member)
18: Automatic transmission 34: Lock-up clutch 80: Electronic control device (control device)

Claims (7)

A vehicle having a lockup clutch capable of directly connecting between input and output rotating members of a fluid transmission device for transmitting engine power to an automatic transmission, and performing a lockup slip control at start-up, in which the lockup clutch is slip-engaged when starting the vehicle A power transmission device control device,
In only when the differential rotation speed before SL lock-up clutch in the start-time lock-up slip control is maximized, the actual engine rotational speed, according to the estimated value of the engine torque when the difference rotational speed is maximum When the vehicle engine speed is lower than the target engine speed, the lockup clutch pressure in the start-up lockup slip control is corrected to a reduced pressure side by learning.   When the differential rotation speed is maximum, the start-up lockup slip control obtained in advance from the start of the start-up lockup slip control until the second predetermined time elapses after the start of the start-up lockup slip control. 2. The control device for a vehicle power transmission device according to claim 1, wherein the determination is made within a predetermined period for viewing the occurrence phenomenon of the differential rotational speed in the vehicle.   The lockup clutch pressure in the start-up lockup slip control is corrected to the pressure increasing side by learning when the actual engine rotation speed is higher than the target engine rotation speed. The control apparatus of the power transmission device for vehicles described in 2.   The lockup clutch pressure in the start-up lockup slip control is corrected to the pressure increasing side by learning when it is determined that the actual engine rotational speed is higher continuously for a predetermined number of times. The control apparatus of the power transmission device for vehicles described in 2.   5. The vehicle power transmission device according to claim 1, wherein a correction amount by learning is increased as a difference between the actual engine rotation speed and the target engine rotation speed increases. 6. Control device.   The control device for a vehicle power transmission device according to claim 5, wherein the correction amount is increased after the difference exceeds a predetermined value.   The target engine speed is experimentally obtained in advance as an engine speed reduced as much as possible in order to improve fuel efficiency in a range where deterioration of drivability is allowed during the start-up lockup slip control. The vehicle power transmission device control device according to any one of claims 1 to 6, wherein the controller is an ideal engine rotation speed when the differential rotation speed is maximum.

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