WO2019167506A1 - Lock-up control device and control method for automatic transmission - Google Patents

Abstract

A belt-type continuously variable transmission (CVT) is provided with a torque converter (2), a lock-up clutch (20), and a CVT control unit (8). A lock-up control unit (80) of the CVT control unit (8) calculates a converter torque (Tcnv) through feed forward compensation based on a target differential rotation speed (ΔN^*) and feedback compensation based on differential rotation speed deviation (δ), and performs slip control using a target LU torque (Tlu^*) obtained by subtracting the converter torque (Tcnv) from an adjusted engine torque (Tadj) inputted to the torque converter (2). The lock-up control unit (80) puts restriction on a converter torque F/B compensation amount (Tcnv_fb) which is calculated through the feedback compensation while an integral term is included for the differential rotation speed deviation (δ).

Description

Lockup control device and control method for automatic transmission

The present invention relates to a lockup control device and control method for an automatic transmission mounted on a vehicle.

Conventionally, the slip lockup of a vehicle that calculates the converter torque by feedforward compensation based on the target differential rotation speed of the lockup clutch and feedback compensation, and controls the differential pressure of the lockup clutch based on the value obtained by subtracting the converter torque from the engine torque. A control device is known (see, for example, Patent Document 1).

In the above-described conventional device, when the operation state where the actual differential rotation speed of the lockup clutch is smaller than the target differential rotation speed continues, the converter torque is increased in the meantime, that is, the differential pressure of the lockup clutch is decreased. The feedback integral term is integrated. When the target differential rotation speed of the lockup clutch decreases from this state, the differential pressure of the lockup clutch increases until the integral term accumulated in the direction to decrease the differential pressure returns to the original value. The time will be longer. As a result, when the lock-up clutch is slip-engaged, there is a problem that the time required until the actual differential rotation speed is reduced is increased.

The present invention has been made paying attention to the above-described problem, and it is an object of the present invention to suppress an increase in the time required for the actual differential rotation speed to be reduced when the lock-up clutch is slip-engaged.

International Publication No. 2017/154506

The present invention includes a torque converter, a lock-up clutch, and a transmission controller.
The transmission controller calculates the converter torque by feedforward compensation based on the target differential speed and feedback compensation based on the differential speed deviation, and the target lockup torque calculated by subtracting the converter torque from the input torque to the torque converter. There is provided a lock-up control unit for executing the obtained slip control.
The lockup control unit limits the torque increase due to integration of the integral term to the converter torque feedback compensation calculated while including the integral term for the differential rotation speed deviation by feedback compensation.

In this way, by reducing the effect of slip control due to integration of the integral term included in the converter torque feedback compensation, the time required until the actual rotational speed decreases when the lockup clutch is slip-engaged increases. Can be suppressed.

1 is an overall system diagram showing a drive system and a control system of an engine vehicle to which a lockup control device for an automatic transmission according to an embodiment is applied. It is a shift schedule figure which shows an example of the D range continuously variable transmission schedule used when the continuously variable transmission control in automatic transmission mode is performed by a variator. It is a schematic block diagram which shows the lockup control apparatus of an Example. It is a block block diagram which shows each block which comprises the lockup control part of a CVT control unit. It is a detailed block diagram which shows the target calculation block, torque capacity calculation block, and realization block which comprise a lockup control part. It is a flowchart which shows the flow of the lockup control process performed in the lockup control part of the CVT control unit of an Example. Target engine rotation speed Ne ^* , actual engine rotation speed Ne, turbine rotation speed Nt, corrected engine torque Tadj, converter torque F / F compensation Tcnv_ff, converter in the transition from LU release to slip LU → LU engagement in the comparative example 6 is a time chart showing characteristics of torque F / B compensation Tcnv_fb, target LU torque Tlu ^*, and lockup hydraulic pressure Plu. Target engine rotation speed Ne ^* / actual engine rotation speed Ne / pre-reading turbine rotation speed Ntpre / correction engine torque Tadj / converter torque F / F compensation Tcnv_ff / 6 is a time chart showing characteristics of converter torque F / B compensation Tcnv_fb, target LU torque Tlu ^*, and lockup hydraulic pressure Plu.

Hereinafter, a mode for carrying out a lockup control device for an automatic transmission according to the present invention will be described based on an embodiment shown in the drawings.

The lockup control device in the embodiment is applied to an engine vehicle equipped with a belt-type continuously variable transmission (an example of an automatic transmission) configured by a torque converter, a forward / reverse switching mechanism, a variator, and a final reduction mechanism. . Hereinafter, the configuration of the embodiment will be described by being divided into “entire system configuration”, “lockup control device configuration”, and “lockup control processing configuration”.

[Overall system configuration]
FIG. 1 shows a drive system and a control system of an engine vehicle to which a lockup control device for an automatic transmission according to an embodiment is applied. The overall system configuration will be described below with reference to FIG.

As shown in FIG. 1, the drive system of the engine vehicle includes an engine 1, a torque converter 2, a forward / reverse switching mechanism 3, a variator 4, a final reduction mechanism 5, and drive wheels 6 and 6. Yes. Here, the belt type continuously variable transmission CVT is configured by incorporating the torque converter 2, the forward / reverse switching mechanism 3, the variator 4, and the final reduction mechanism 5 in a transmission case (not shown).

The engine 1 can control the output torque by an engine control signal from the outside, in addition to the output torque control by the accelerator operation by the driver. The engine 1 includes an output torque control actuator 10 that performs torque control by a throttle valve opening / closing operation, a fuel cut operation, and the like. For example, fuel cut control is executed during coasting by an accelerator release operation.

The torque converter 2 is a starting element by a fluid coupling having a torque increasing function and a torque fluctuation absorbing function. The torque converter 2 has a lock-up clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21 when a torque increasing function and a torque fluctuation absorbing function are not required. The torque converter 2 includes a pump impeller 23, a turbine runner 24, and a stator 26 as constituent elements. The pump impeller 23 is connected to the engine output shaft 11 via the converter housing 22. The turbine runner 24 is connected to the torque converter output shaft 21. The stator 26 is provided in the transmission case via the one-way clutch 25.

The forward / reverse switching mechanism 3 is a mechanism that switches the input rotation direction to the variator 4 between a forward rotation direction during forward travel and a reverse rotation direction during reverse travel. The forward / reverse switching mechanism 3 includes a double pinion planetary gear 30, a forward clutch 31 using a plurality of clutch plates, and a reverse brake 32 using a plurality of brake plates. The forward clutch 31 is hydraulically engaged by the forward clutch pressure Pfc when a forward travel range such as the D range is selected. The reverse brake 32 is hydraulically engaged by the reverse brake pressure Prb when the reverse travel range such as the R range is selected. The forward clutch 31 and the reverse brake 32 are both released by draining the forward clutch pressure Pfc and the reverse brake pressure Prb when the N range (neutral range) is selected.

The variator 4 has a primary pulley 42, a secondary pulley 43, and a pulley belt 44, and continuously changes the transmission gear ratio (ratio of variator input rotation to variator output rotation) by changing the belt contact diameter. A gear shifting function is provided. The primary pulley 42 includes a fixed pulley 42 a and a slide pulley 42 b arranged on the same axis as the variator input shaft 40, and the slide pulley 42 b is slid by the primary pressure Ppri guided to the primary pressure chamber 45. The secondary pulley 43 includes a fixed pulley 43 a and a slide pulley 43 b arranged on the same axis as the variator output shaft 41, and the slide pulley 43 b is slid by the secondary pressure Psec guided to the secondary pressure chamber 46. The pulley belt 44 is stretched around a sheave surface that forms a V shape of the primary pulley 42 and a sheave surface that forms a V shape of the secondary pulley 43. The pulley belt 44 is formed of two sets of laminated rings in which a large number of annular rings are stacked from the inside to the outside and a plurality of punched plate members, and is attached by being laminated in an annular manner by being sandwiched along the two sets of laminated rings. It is composed of elements. The pulley belt 44 may be a chain-type belt in which a large number of chain elements arranged in the pulley traveling direction are coupled by pins penetrating in the pulley axial direction.

The final deceleration mechanism 5 is a mechanism that decelerates the variator output rotation from the variator output shaft 41 and transmits it to the left and right drive wheels 6 and 6 while providing a differential function. The final speed reduction mechanism 5 is a speed reduction gear mechanism that includes an output gear 52 provided on the variator output shaft 41, an idler gear 53 and a reduction gear 54 provided on the idler shaft 50, and a final gear provided on the outer peripheral position of the differential case. And a gear 55. The differential gear mechanism includes a differential gear 56 interposed between the left and right drive shafts 51, 51.

As shown in FIG. 1, the engine vehicle control system includes a hydraulic control unit 7, a CVT control unit 8, and an engine control unit 9. The CVT control unit 8 and the engine control unit 9 which are electronic control systems are connected by a CAN communication line 13 which can exchange information with each other.

The hydraulic control unit 7 performs primary pressure Ppri guided to the primary pressure chamber 45, secondary pressure Psec guided to the secondary pressure chamber 46, forward clutch pressure Pfc to the forward clutch 31, reverse brake pressure Prb to the reverse brake 32, and the like. It is a unit that regulates pressure. The hydraulic control unit 7 includes an oil pump 70 that is rotationally driven by the engine 1 that is a travel drive source, and a hydraulic control circuit 71 that adjusts various control pressures based on the discharge pressure from the oil pump 70. . The hydraulic control circuit 71 includes a line pressure solenoid valve 72, a primary pressure solenoid valve 73, a secondary pressure solenoid valve 74, a select solenoid valve 75, and a lockup pressure solenoid valve 76. Each solenoid valve 72, 73, 74, 75, 76 performs a pressure adjustment operation according to a control command value (indicated current) output from the CVT control unit 8.

The line pressure solenoid valve 72 adjusts the discharge pressure from the oil pump 70 to the commanded line pressure PL according to the line pressure command value output from the CVT control unit 8. The line pressure PL is a source pressure when adjusting various control pressures, and is a hydraulic pressure that suppresses belt slip and clutch slip against torque transmitted through the drive system.

The primary pressure solenoid valve 73 adjusts the pressure to the primary pressure Ppri commanded using the line pressure PL as the original pressure in accordance with the primary pressure command value output from the CVT control unit 8. The secondary pressure solenoid valve 74 adjusts the pressure to the secondary pressure Psec commanded using the line pressure PL as the original pressure in accordance with the secondary pressure command value output from the CVT control unit 8.

The select solenoid valve 75 adjusts the pressure to the forward clutch pressure Pfc or the reverse brake pressure Prb commanded using the line pressure PL as the original pressure according to the forward clutch pressure command value or the reverse brake pressure command value output from the CVT control unit 8. To do.

The lock-up pressure solenoid valve 76 adjusts to a lock-up hydraulic pressure Plu for engaging / slipping / releasing the lock-up clutch 20 according to the command current Alu output from the CVT control unit 8.

The CVT control unit 8 performs line pressure control, shift control, forward / reverse switching control, lockup control, and the like. In the line pressure control, a command value for obtaining a target line pressure corresponding to the accelerator opening is output to the line pressure solenoid valve 72. In the shift control, when the target gear ratio (target primary rotation Npri ^* ) is determined, a command value for obtaining the determined target gear ratio (target primary rotation Npri ^* ) is output to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74. In the forward / reverse switching control, a command value for controlling the engagement / release of the forward clutch 31 and the reverse brake 32 is output to the select solenoid valve 75 according to the selected range position. In the lockup control, the command current Alu for controlling the lockup hydraulic pressure Plu for engaging / slipping / releasing the lockup clutch 20 is output to the lockup pressure solenoid valve 76.

The CVT control unit 8 includes a primary rotation sensor 90, a vehicle speed sensor 91, a secondary pressure sensor 92, an oil temperature sensor 93, an inhibitor switch 94, a brake switch 95, a turbine rotation sensor 96, a secondary rotation sensor 97, a primary pressure sensor 98, and the like. Sensor information and switch information are input.

The engine control unit 9 receives sensor information from the engine rotation sensor 12, accelerator opening sensor 14, and the like. When the CVT control unit 8 requests the engine control information and the accelerator opening information to the engine control unit 9, the CVT control unit 8 receives information on the engine speed Ne and the accelerator opening APO via the CAN communication line 13. Further, when requesting engine torque information to the engine control unit 9, information on the actual engine torque Te estimated in the engine control unit 9 is received via the CAN communication line 13.

FIG. 2 shows an example of the D range continuously variable transmission schedule used when the variator 4 executes the continuously variable transmission control in the automatic transmission mode when the D range is selected.

The “D range shift mode” is an automatic shift mode in which the gear ratio is automatically changed steplessly in accordance with the vehicle operating state. The shift control in the “D range shift mode” is performed by operating points on the D range continuously variable shift schedule of FIG. 2 specified by the vehicle speed VSP (vehicle speed sensor 91) and the accelerator opening APO (accelerator opening sensor 14) ( VSP, APO) determines the target primary rotational speed Npri ^* . Then, the pulley primary pressure control is performed so that the actual primary rotational speed Npri from the primary rotational sensor 90 matches the target primary rotational speed Npri ^* .

That is, as shown in FIG. 2, the D range continuously variable transmission schedule used in the “D range speed change mode” has a gear ratio range of the lowest gear ratio and the highest gear ratio according to the operating point (VSP, APO). Within the range, the gear ratio is set to change steplessly. For example, when the vehicle speed VSP is constant, and shifting the downshift direction to perform the increased target primary rotation speed Npri ^* the accelerator depression operation, the target primary rotation speed Npri ^* decreases Doing accelerator return operation up Shift in the shift direction. When the accelerator opening APO is constant, the vehicle shifts in the upshift direction when the vehicle speed VSP increases, and the vehicle shifts in the downshift direction when the vehicle speed VSP decreases.

[Configuration of lock-up control device]
FIG. 3 shows the lock-up control device of the embodiment. Hereinafter, a schematic configuration of the lockup control device will be described with reference to FIG. In the following, lockup is abbreviated as “LU”, feedforward is abbreviated as “F / F”, and feedback is abbreviated as “F / B”.

As shown in FIG. 3, the drive system to which the lockup control device is applied includes an engine 1 (driving drive source), a torque converter 2 having a lockup clutch 20, a forward / reverse switching mechanism 3, and a variator 4. The final reduction mechanism 5 and the drive wheels 6 are provided.

As shown in FIG. 3, the control system to which the lockup control device is applied includes a CVT control unit 8, an engine control unit 9, and a lockup pressure solenoid valve 76. The CVT control unit 8 is provided with a lockup control unit 80 that changes the clutch state of the lockup clutch 20 to the engaged state / slip engaged state / released state according to various requests.

The lockup control in the lockup control unit 80 estimates the target driving force Fd ^* intended by the driver, and locks up the clutch so that the actual driving force Fd output to the driving wheels 6 becomes the target driving force Fd ^*. 20 slip control is performed. At this time, the target driving force Fd ^* is converted into the target engine speed Ne ^* in order to improve the controllability in the slip control. The converter torque Tcnv is calculated by executing control (F / F control + F / B control) for converging the actual engine speed Ne to the target engine speed Ne ^* . Then, as shown in FIG. 3, Tadj = Tcnv + Tlu relationship that holds, calculates a target LU torque TLU of the lockup clutch 20 ^*, the target LU torque TLU ^* the obtained command current Alu lockup pressure solenoid valve 76 Output to. Thus, by controlling the torque ratio of the torque converter 2 so as to obtain the target engine speed Ne ^* , the target driving force Fd ^* intended by the driver can be realized during the slip control of the lockup clutch 20. it can.

FIG. 4 shows each block constituting the lockup control unit 80 of the CVT control unit 8. Hereinafter, the block configuration of the lockup control unit 80 will be described with reference to FIG.

The lockup control unit 80 includes a driving force demand block 81, a request arbitration block 82, a target calculation block 83, a torque capacity calculation block 84, and an implementation block 85, as shown in FIG.

The driving force demand block 81 calculates the target driving force Fd ^* based on the accelerator opening APO and the vehicle speed VSP, and converts the target driving force Fd ^* into the target engine speed Ne ^* using the engine overall performance characteristics. The profile of the target engine speed Ne ^* is calculated. When the lockup clutch 20 is completely released, the engagement request flag is output when the profile of the target engine speed Ne ^* is realized by the clutch slip control. On the other hand, when the lock-up clutch 20 is completely engaged, a release request flag is output when a profile of the target engine speed Ne ^* is realized by clutch slip control.

The request arbitration block 82 receives the engagement request flag and the release request flag from the driving force demand block 81, calculates a lockup request from various requests, and arbitrates the request to determine the priority. Various requirements include basic requirements, DP requirements (DP stands for Driving pleasure), drivability requirements, protection requirements, FS requirements (FS stands for Fail Safe), technical limit requirements, other system requirements, coast slip requirements, Etc.

The target calculation block 83 inputs the immediate release request flag, the release request flag, the slip request flag, and the engagement request flag from the request arbitration block 82, and calculates the target differential rotation speed ΔN ^* as a differential rotation target from these LU requests. . In the target calculation block 83, the target engine speed Ne ^* calculated by the driving force demand block 81 is input.

The torque capacity calculation block 84 inputs the target differential rotation speed ΔN ^* , the look-ahead turbine rotation speed Ntpre, and the actual engine rotation speed Ne from the target calculation block 83. Then, the command torque (target LU torque Tlu ^* ) for realizing the target differential rotation speed ΔN ^* is calculated by calculating the corrected engine torque Tadj and the converter torque Tcnv (F / F control + F / B control).

The realization block 85 receives the target LU torque Tlu ^* from the torque capacity calculation block 84, converts the target lockup torque Tlu ^* into the lockup hydraulic pressure Plu, and further converts the lockup hydraulic pressure Plu into the command current Alu.

FIG. 5 shows a target calculation block 83, a torque capacity calculation block 84, and a realization block 85 that constitute the lockup control unit 80. The detailed configuration of each of the blocks 83, 84, and 85 will be described below with reference to FIG.

The target calculation block 83 includes a pre-read turbine rotational speed calculator 83a and a first subtractor 83b.

The prefetch turbine rotational speed calculator 83a inputs the prefetch speed ratio of the variator 4 and the secondary rotational speed Nsec from the secondary rotational sensor 97, and calculates the prefetch turbine rotational speed Ntpre that compensates for the hydraulic response delay in the lockup hydraulic control. To do. Note that the look-ahead gear ratio of the variator 4 is a gear ratio that is estimated to be reached when the hydraulic response delay time elapses, using the gear ratio, the speed ratio progress speed, and the hydraulic response delay time at that time.

The first subtractor 83b calculates the target differential rotation speed ΔN ^{* based} on the difference between the target engine speed Ne ^* calculated by the driving force demand block 81 and the prefetch turbine speed Ntpre calculated by the prefetch turbine speed calculator 83a. To do.

The torque capacity calculation block 84 has a look-ahead engine torque calculator 84a, a first adder 84b, a pump load torque calculator 84c, and a second differentiator 84d in the corrected engine torque calculation area 841.

The look-ahead engine torque calculator 84a receives the accelerator opening APO and the actual engine speed Ne, and uses a total engine performance map to estimate the look-ahead engine torque estimated to vary from the current engine torque to the hydraulic response delay time. ΔTepre is calculated. The current engine torque is acquired from the current accelerator opening APO, the actual engine speed Ne, and the engine overall performance map. The engine torque ΔTepre for the look-ahead is calculated by using the change rate of the accelerator opening APO and the actual engine speed Ne and the hydraulic response delay time, and the change width (positive or negative) of the engine torque from the current time until the hydraulic response delay time elapses. To do.

The first adder 84b calculates the pre-read engine torque Tepre by adding the actual engine torque Te acquired from the engine control unit 9 and the pre-read engine torque ΔTepre from the pre-read engine torque calculator 84a.

The pump load torque calculator 84c calculates a pump load torque Top that is a load torque by the oil pump 70 when being rotated by the engine 1.

The second subtractor 84d calculates a corrected engine torque Tadj (= Tepre-Top) based on the difference between the pre-read engine torque Tepre calculated by the first adder 84b and the pump load torque Top calculated by the pump load torque calculator 84c. To do.

The torque capacity calculation block 84 includes an F / F compensator 84e, a third difference unit 84f, a fourth difference unit 84g, an F / B compensator 84h, a minimum value selector 84i, and a second adder 84j. In the converter torque calculation area 842.

The F / F compensator 84e receives the target differential rotational speed ΔN ^* (= target slip rotational speed) from the first differentiator 83b, and calculates the converter torque F / F compensation Tcnv_ff corresponding to the target differential rotational speed ΔN ^*. calculate.

The third subtractor 84f inputs the actual engine rotational speed Ne from the engine rotational sensor 12 and the prefetch turbine rotational speed Ntpre calculated by the prefetch turbine rotational speed calculator 83a. Then, the actual differential speed ΔN is calculated from the difference between the actual engine speed Ne and the look-ahead turbine speed Ntpre.

The fourth subtractor 84g receives the target differential rotation speed ΔN ^* (= target slip rotation speed) from the first subtractor 83b and the actual differential rotation speed ΔN (= actual slip rotation speed) from the third subtractor 84f. To do. Then, a differential rotational speed deviation δ is calculated from the difference between the target differential rotational speed ΔN ^* and the actual differential rotational speed ΔN.

The F / B compensator 84h receives the difference rotational speed deviation δ from the fourth differentiator 84g and performs PI feedback control on the converter torque F / B compensation calculated value Tcnv_fb (c) corresponding to the differential rotational speed deviation δ. (P: proportional, I: integral). This F / B compensator 84h, when the coast slip request is made due to the establishment of the coast slip control start condition in the request arbitration block 82, the converter torque F / B compensation component calculated value Tcnv_fb (c) up to that point is initialized. Reset to.

The minimum value selector 84i inputs the converter torque F / B compensation calculated value Tcnv_fb (c) from the F / B compensator 84h and the upper limit torque value Tcnv_max for the converter torque F / B compensation. Then, the converter torque F / B compensation Tcnv_fb is output by selecting the minimum value.

Here, the upper limit torque value Tcnv_max for the converter torque F / B compensation is
Tcnv_max = Tadj−Tcnv_ff−K (K: fixed value)… (1)
(1), that is, a variable torque value corresponding to the corrected engine torque Tadj and the converter torque F / F compensation Tcnv_ff. Note that the fixed value K is set to be the upper limit torque value Tcnv_max that promotes the increase of the target LU torque Tlu ^* in the slip engagement scene of the lockup clutch 20. However, if the fixed value K is set to a torque value that is too low, the corrected engine torque Tadj that is the input torque to the torque converter 2 may not be exceeded due to the sum of the converter torque F / F compensation Tcnv_ff and the fixed value K. . That is, the target LU torque Tlu ^* does not become zero during the slip release scene of the lockup clutch 20, and the lockup clutch 20 cannot be released. Therefore, the fixed value K is a torque value that can exceed the corrected engine torque Tadj, which is the input torque to the torque converter 2, by considering the slip release scene of the lockup clutch 20 and the sum of the fixed value K and the converter torque F / F compensation. Set to the minimum value.

The second adder 84j adds the converter torque F / F compensation Tcnv_ff from the F / F compensator 84e and the converter torque F / B compensation Tcnv_fb from the minimum value selector 84i to calculate the converter torque Tcnv.

The torque capacity calculation block 84 includes a fifth differentiator 84k outside the corrected engine torque calculation area 841 and the converter torque calculation area 842. The fifth subtractor 84k calculates the target LU torque Tlu ^* by subtracting the corrected engine torque Tadj from the second subtractor 84d and the converter torque Tcnv from the second adder 84j.

The realization block 85 includes a torque → hydraulic converter 85a and a hydraulic → current converter 85b. The torque → hydraulic pressure converter 85a converts the target LU torque Tlu ^* input from the torque capacity calculation block 84 into the LU hydraulic pressure Plu. The hydraulic pressure → current converter 85b converts the LU hydraulic pressure Plu input from the torque → hydraulic converter 85a into an instruction current Alu.

[Lockup control processing configuration]
FIG. 6 shows the flow of lockup control processing executed by the lockup control unit 80 of the CVT control unit 8 of the embodiment. Hereinafter, each step of FIG. 6 showing the lockup control processing configuration of the embodiment will be described. This process is repeatedly performed in a predetermined control cycle.

In step S1, following the start, the pre-reading turbine rotational speed Ntpre is calculated, and the process proceeds to step S2.

Here, the look-ahead turbine speed Ntpre is the turbine speed that compensates for the hydraulic response delay in the lock-up hydraulic control. The prefetch turbine rotational speed Ntpre is calculated in the prefetch turbine rotational speed calculator 83 a based on the prefetch speed ratio of the variator 4 and the secondary rotational speed Nsec from the secondary rotation sensor 97.

In step S2, following the calculation of the pre-reading turbine rotational speed Ntpre in step S1, a pre-reading engine torque Tepre is calculated, and the process proceeds to step S3.

Here, the look-ahead engine torque Tepre is an engine torque that compensates for the hydraulic response delay in the lockup hydraulic control. The pre-read engine torque Tepre is calculated by adding the actual engine torque Te acquired from the engine control unit 9 and the pre-read engine torque ΔTepre in the pre-read engine torque calculator 84a and the first adder 84b.

In step S3, following the calculation of the pre-reading engine torque Tepre in step S2, a corrected engine torque Tadj is calculated, and the process proceeds to step S4.

Here, the corrected engine torque Tadj is an engine torque input to the torque converter 2. The corrected engine torque Tadj is calculated in the second subtractor 84d by the difference between the pre-read engine torque Tepre and the pump load torque Top.

In step S4, subsequent to the calculation of the correction engine torque Tadj in step S3, based on the target rotational speed difference .DELTA.N ^*, calculates the converter torque F / F compensation min Tcnv_ff in accordance with the target rotational speed difference .DELTA.N ^*, step S5 Proceed to

The target differential speed ΔN ^* is calculated in the first subtractor 83b based on the difference between the target engine speed Ne ^* and the look-ahead turbine speed Ntpre. The converter torque F / F compensation Tcnv_ff is the F / F of the lockup torque that converges to the target differential rotational speed ΔN ^* in the F / F compensator 84e that inputs the target differential rotational speed ΔN ^* (= target slip rotational speed). Calculated as compensation.

In step S5, following the calculation of the converter torque F / F compensation amount Tcnv_ff in step S4, the converter torque F / B compensation calculated value Tcnv_fb (c ) And the process proceeds to step S6.

Here, the differential rotational speed deviation δ is determined by the fourth differential unit 84g by the target differential rotational speed ΔN ^* (= target slip rotational speed) from the first differential unit 83b and the actual differential rotational speed from the third differential unit 84f. It is calculated from the difference in ΔN (= actual slip rotation speed). The converter torque F / B compensation calculated value Tcnv_fb (c) is calculated by the F / B compensator 84h as the converter torque F / B compensation for matching the actual slip rotation speed with the target slip rotation speed.

In step S6, following the calculation of converter torque F / B compensation calculation value Tcnv_fb (c) in step S5, converter torque F / B compensation calculation value Tcnv_fb (c) is the upper limit of converter torque F / B compensation. It is determined whether or not the torque value is equal to or less than Tcnv_max. If YES (Tcnv_fb (c) ≦ Tcnv_max), the process proceeds to step S7. If NO (Tcnv_fb (c)> Tcnv_max), the process proceeds to step S8.

In step S7, following the determination that Tcnv_fb (c) ≦ Tcnv_max in step S6, the converter torque F / B compensation amount Tcnv_fb is set as the converter torque F / B compensation calculated value Tcnv_fb (c), and the process proceeds to step S9. move on.

In step S8, following the determination that Tcnv_fb (c)> Tcnv_max in step S6, the converter torque F / B compensation amount Tcnv_fb is set as the upper limit torque value Tcnv_max for the converter torque F / B compensation, and the process proceeds to step S9. .

Here, the selection of the converter torque F / B compensation Tcnv_fb in steps S6 to S8 is performed in the minimum value selector 84i.

In step S9, following the setting of the converter torque F / B compensation Tcnv_fb in step S7 or step S8, the converter torque Tcnv is calculated, and the process proceeds to step S10.

Here, the converter torque Tcnv is calculated by adding the converter torque F / F compensation Tcnv_ff from the F / F compensator 84e and the converter torque F / B compensation Tcnv_fb from the minimum value selector 84i.

In step S10, following calculation of converter torque Tcnv in step S9, target LU torque Tlu ^* is calculated, and the process proceeds to step S11.

Here, the target LU torque Tlu ^* is calculated by subtracting the corrected engine torque Tadj calculated in step S3 and the converter torque Tcnv calculated in step S9 in the fifth differentiator 84k.

In step S11, following the calculation of the target LU torque Tlu ^* in step S10, the torque LU pressure converter 85a converts the target LU torque Tlu ^* into the LU oil pressure Plu, and the process proceeds to step S12.

In step S12, following the conversion to the LU hydraulic pressure Plu in step S11, the hydraulic pressure → current converter 85b converts the LU hydraulic pressure Plu to the command current Alu, and the process proceeds to step S13.

In step S13, following the conversion to the instruction current Alu in step S12, the instruction current Alu is output to the lockup pressure solenoid valve 76, and the process proceeds to the end.

Next, the operation of the embodiment will be described by dividing it into “About lock-up control and its problem in the comparative example” and “Lock-up control operation”.

[About lock-up control and its problems in the comparative example]
FIG. 7 is a time chart showing characteristics in a transition scene from LU release → slip LU → LU engagement in the comparative example. Hereinafter, the lock-up control and its problem in the comparative example will be described with reference to FIG.

In the comparative example, the converter torque is calculated by feedforward compensation based on the target differential rotational speed of the lockup clutch and feedback compensation based on the differential rotational speed deviation. The differential pressure of the lockup clutch is controlled based on the value obtained by subtracting the converter torque from the engine torque.

In the case of this comparative example, when the engagement request flag is set at time t1 in FIG. 7 in the lock-up clutch released state, supply of the lock-up hydraulic pressure Plu is started. When the slip request flag is set at time t2 due to the start of the accelerator depression operation, the slip fastening control is started.

At slip engagement control start time t2, the operating state in which the actual differential speed (actual engine speed Ne-turbine speed Nt) of the lockup clutch is greater than the target differential speed (target engine speed Ne ^* -turbine speed Nt). It becomes. That is, when the differential rotational speed deviation (target differential rotational speed-actual differential rotational speed) becomes negative, the converter torque F / B compensation amount Tcnv_fb decreases at a stretch. From time t2 to time t3, the negative differential rotational speed deviation becomes smaller due to the increase in the target engine speed Ne ^* of the lockup clutch, so that the converter torque F / B compensation Tcnv_fb gradually decreases.

When the target engine speed Ne ^* exceeds the actual engine speed Ne at time t3, the target engine speed Ne ^* and the actual engine speed Ne after time t3 as shown in the in-frame characteristics of the arrow A in FIG. The differential rotational speed is increased, and the differential rotational speed decreases toward time t4. As described above, when the operation state in which the actual differential rotation speed of the lockup clutch is smaller than the target differential rotation speed continues, the direction in which the converter torque is increased, that is, the differential pressure of the lockup clutch is decreased from time t3 to time t4. The integral term in the feedback compensation is integrated in the direction of For this reason, converter torque F / B compensation Tcnv_fb starts to increase due to integration of the integral term immediately after time t3, and the integration amount of the integral term becomes the largest in the vicinity of time t4. That is, as indicated by the in-frame characteristics of the arrow B in FIG. 7, the converter torque F / B compensation amount Tcnv_fb rises rapidly and exceeds the corrected engine torque Tadj on the way. Therefore, as indicated by the in-frame characteristics indicated by the arrow C in FIG. 7, the target LU torque Tlu ^* decreases as the converter torque F / B compensation amount Tcnv_fb increases rapidly.

After a lapse of time from time t3, the lock-up clutch becomes insufficient in the engagement torque due to the decrease in the target LU torque Tlu ^* , and the clutch release side slip control is performed. For this reason, the actual engine speed Ne increases, and as shown in the in-frame characteristics of the arrow D in FIG. 7, the actual differential speed of the lockup clutch again shifts to an operating state greater than the target differential speed. As a result, an engine speed difference ΔNe is generated, and the convergence of the actual engine speed Ne to the target engine speed Ne ^* is deteriorated.

In the region where the target differential rotation speed of the lockup clutch after time t4 decreases, the converter torque F / B compensation amount Tcnv_fb decreases from the peak state with a gradual decrease gradient. In other words, it takes time for the integral term integrated in the direction to reduce the differential pressure to return to the original, and the time until the differential pressure of the lockup clutch increases by the amount of time until it returns to the original. . As a result, when the lockup clutch is slip-engaged, the time required until the actual rotational speed decreases becomes longer, such as the time TC from the slip engagement control start time t2 to the lockup engagement time t6 becomes longer. End up.

[Lock-up control action]
In the case of the comparative example described above, the inventors have found that an engine speed difference ΔNe is generated during slip engagement control, and the convergence of the actual engine speed Ne to the target engine speed Ne ^* deteriorates or the actual difference speed. It has been found that it takes a long time to become smaller. Then, as a result of searching for the cause of this problem, it was elucidated that the integral term of the converter torque F / B compensation Tcnv_fb was accumulated in the slip engagement scene where the target engine speed Ne ^* increased rapidly It was done.

Therefore, paying attention to the converter torque F / B compensation amount Tcnv_fb calculated by the feedback compensator 84h including the integral term for the difference in rotational speed deviation δ, the converter torque F / B compensation amount Tcnv_fb is obtained by integrating the integral term. A configuration that restricts the rise was adopted. More specifically, the increase in the converter torque F / B compensation calculated value Tcnv_fb (c) calculated by the feedback compensator 84h is limited by the upper limit torque value Tcnv_max.

In this way, by limiting the converter torque F / B compensation amount Tcnv_fb, slip control by integrating the integral term is performed in the slip engagement scene where the target engine speed Ne ^* increases rapidly and the integral term is accumulated. The influence of is reduced. As a result, when the lock-up clutch 20 is slip-engaged, it is possible to suppress an increase in the time required until the actual rotational speed ΔN becomes small.

First, the operation of the lockup control process will be described based on the flowchart shown in FIG.
If Tcnv_fb (c) ≦ Tcnv_max during slip control of the lockup clutch 20, in the flowchart of FIG. 6, S1 → S2 → S3 → S4 → S5 → S6 → S7 → S9 → S10 → S11 → S12 → S13 → Proceed to the end.

That is, if it is determined in step S6 that the converter torque F / B compensation calculated value Tcnv_fb (c) is equal to or less than the upper limit torque value Tcnv_max, the process proceeds to step S7. In step S7, the converter torque F / B compensation calculation value Tcnv_fb (c) is used as it is as the converter torque F / B compensation Tcnv_fb.

On the other hand, when Tcnv_fb (c)> Tcnv_max during the slip control of the lockup clutch 20, in the flowchart of FIG. 6, S1 → S2 → S3 → S4 → S5 → S6 → S8 → 9 → S10 → S11 → S12 → The process proceeds from S13 to END.

That is, if it is determined in step S6 that the converter torque F / B compensation calculated value Tcnv_fb (c) exceeds the upper limit torque value Tcnv_max, the process proceeds to step S8. In step S8, upper limit torque value Tcnv_max is used as converter torque F / B compensation Tcnv_fb.

In step S9, converter torque Tcnv is calculated by adding converter torque F / F compensation Tcnv_ff and converter torque F / B compensation Tcnv_fb. In step S10, the target LU torque Tlu ^* is calculated by subtracting the converter torque Tcnv from the corrected engine torque Tadj. In step S11, the target LU torque Tlu ^* is converted into the LU hydraulic pressure Plu. In the next step S12, the LU hydraulic pressure Plu is converted into the command current Alu. In step S13, the command current Alu is output to the lockup pressure solenoid valve 76.

Next, the lock-up control action in the transition scene from LU release → slip LU → LU engagement will be described based on the time chart shown in FIG.

In this embodiment, when the engagement request flag is set at time t1 in FIG. 8 in the lock-up clutch released state, supply of the lock-up hydraulic pressure Plu is started. When the slip request flag is set at time t2 due to the start of the accelerator depression operation, the slip fastening control is started.

At the slip engagement control start time t2, the operation state is such that the actual differential rotation speed of the lockup clutch is greater than the target differential rotation speed. That is, the converter torque F / B compensation amount Tcnv_fb is reduced at a stretch as the differential rotation speed deviation becomes negative. From time t2 to time t3, the negative differential rotational speed deviation becomes smaller due to the increase in the target engine speed Ne ^* of the lockup clutch, so that the converter torque F / B compensation Tcnv_fb gradually decreases.

When the target engine speed Ne ^* exceeds the actual engine speed Ne at time t3, the difference engine speed between the target engine speed Ne ^* and the actual engine speed Ne is increased after time t3. Along with this, the differential rotation speed decreases. As described above, when the operation state in which the actual rotational speed of the lockup clutch is smaller than the target differential rotational speed continues, the converter torque F / B compensation calculated value Tcnv_fb (c) is calculated by integrating the integral term immediately after time t3. The integral term in the feedback compensation is accumulated in the direction of increasing the converter torque, that is, in the direction of decreasing the differential pressure of the lock-up clutch until the time t4 ′ is reached.

However, when the converter torque F / B compensation calculated value Tcnv_fb (c) reaches the upper limit torque value Tcnv_max at time t4 ′, the increase of the converter torque F / B compensation Tcnv_fb is suppressed and exceeds the corrected engine torque Tadj. Without passing time t4. That is, as indicated by an arrow E in FIG. 8, the converter torque F / B compensation amount Tcnv_fb at time t4 in the comparative example is kept low to the upper limit torque value Tcnv_max. Therefore, the target LU torque Tlu ^* increases from time t4 onward as the converter torque F / B compensation amount Tcnv_fb is suppressed.

After the time t4 ′, the tightening torque of the lockup clutch 20 is secured by the increase of the target LU torque Tlu ^* , and the clutch engagement side slip control is performed. For this reason, an increase in the actual engine rotational speed Ne is suppressed, and the actual differential rotational speed of the lockup clutch 20 does not shift to an operating state larger than the target differential rotational speed as in the comparative example. Thereby, as shown by the in-frame characteristics of the arrow F in FIG. 8, the convergence is ensured such that the actual engine speed Ne gradually converges with respect to the target engine speed Ne ^* after time t4 ′. .

Then, in a region where the target differential rotation speed of the lockup clutch after time t4 ′ decreases, converter torque F / B compensation Tcnv_fb increases with a gradual upward gradient. That is, after the time t4 ′, the time until the differential pressure of the lockup clutch 20 increases is shortened by urging the target LU torque Tlu ^* to increase (i.e., the increase of the lockup hydraulic pressure Plu). As a result, when the lockup clutch 20 is slip-engaged, the actual differential rotation speed is such that the time TI (<TC) required from the slip engagement control start time t2 to the lockup engagement time t5 (<t6) is shortened. The time required to become smaller is shortened.

As described above, in the lock-up control device of the belt type continuously variable transmission CVT of the embodiment, the effects listed below can be obtained.

(1) The torque converter 2, the lockup clutch 20, and the transmission controller (CVT control unit 8) are provided.
The torque converter 2 is interposed between the travel drive source (engine 1) and the speed change mechanism (variator 4).
The lock-up clutch 20 is provided in the torque converter 2 and directly connects the torque converter input shaft and the torque converter output shaft by fastening.
The transmission controller (CVT control unit 8) controls the engagement / slip / release of the lock-up clutch 20.
The transmission controller (CVT control unit 8) calculates the converter torque Tcnv by feedforward compensation based on the target differential rotational speed ΔN ^* and feedback compensation based on the differential rotational speed deviation δ, and the input torque (correction engine) to the torque converter 2 is calculated. A lockup control unit 80 is provided that performs slip control to obtain a target lockup torque Tlu ^* calculated by subtracting the converter torque Tcnv from the torque Tadj).
The lock-up control unit 80 limits the torque increase due to integration of the integral term to the converter torque F / B compensation amount Tcnv_fb calculated while including the integral term with respect to the differential rotational speed deviation δ by feedback compensation.
As described above, by reducing the influence of the slip control due to the integration of the integral term included in the converter torque F / B compensation amount Tcnv_fb, it is necessary for the actual differential rotation speed ΔN to be reduced when the lockup clutch 20 is slip-engaged. It can suppress that time becomes long.

(2) The lockup control unit 80 limits the increase in the converter torque F / B compensation calculated value Tcnv_fb (c) calculated by feedback compensation by the upper limit torque value Tcnv_max.
While the upper limit torque value Tcnv_max is urged to increase the target lockup torque (target LU torque Tlu ^* ) in the slip engagement scene of the lockup clutch 20, the upper limit torque value Tcnv_max is increased in the slip release scene of the lockup clutch 20. Set to a torque value that guarantees release.
In this way, by setting the upper limit torque value Tcnv_max in consideration of slip engagement and slip release, it is possible to guarantee the transition from slip release to clutch release while shortening the transition time from slip engagement to clutch engagement. Can do.

(3) The lockup control unit 80 calculates the upper limit torque value Tcnv_max by subtracting the converter torque F / F compensation Tcnv_ff and the fixed value K from the input torque (corrected engine torque Tadj) to the torque converter 2 (1). give.
The fixed value K is set to the minimum value among the torque values that can exceed the input torque (corrected engine torque Tadj) to the torque converter 2 by the sum of the converter torque F / F compensation Tcnv_ff.
In this way, by setting the upper limit torque value Tcnv_max to the minimum value among the values that achieve both slip fastening time reduction and slip release guarantee, it is possible to achieve both effective slip fastening time reduction and reliable slip release guarantee. Can be achieved.

(4) The lockup control unit 80 converts the target driving force Fd ^* required by the driver into the target driving source rotational speed (target engine rotational speed Ne ^* ) of the traveling driving source (engine 1). And it has a feedforward compensator (F / F compensator 84e) and a feedback compensator (F / B compensator 84h).
The feedforward compensator (F / F compensator 84e) is based on a target differential rotational speed ΔN ^* that is a difference between a target drive source rotational speed (target engine rotational speed Ne ^* ) and a turbine rotational speed (prefetch turbine rotational speed Ntpre). Perform feedforward compensation.
The feedback compensator (F / B compensator 84h) calculates the actual difference rotational speed ΔN based on the difference between the actual driving source rotational speed (actual engine rotational speed Ne) and the turbine rotational speed (pre-reading turbine rotational speed Ntpre). Feedback compensation is performed based on the difference in rotational speed deviation δ which is the difference between the rotational speed ΔN ^* and the actual differential rotational speed ΔN.
Thus, by controlling the torque ratio of the torque converter 2 so as to obtain the target engine speed Ne ^* , the target driving force Fd ^* intended by the driver can be realized during the slip control of the lockup clutch 20. it can.

The automatic transmission lockup control device of the present invention has been described above based on the embodiments. However, the specific configuration is not limited to the first embodiment, and design changes and additions are allowed without departing from the spirit of the invention according to each claim of the claims.

In the embodiment, as the lockup control unit 80, an example is shown in which the increase in the converter torque F / B compensation calculation value Tcnv_fb (c) calculated by the F / B compensator 84h is limited by the upper limit torque value Tcnv_max. However, the lockup control unit may be an example of limiting the rising slope of the calculated value of the converter torque F / B compensation calculated by the F / B compensator.

In the embodiment, an example in which the upper limit torque value Tcnv_max is given by the equation (1) obtained by subtracting the converter torque F / F compensation Tcnv_ff and the fixed value K from the corrected engine torque Tadj that is the input torque to the torque converter 2 is shown. However, the lockup control unit may be an example in which the upper limit torque value is set only by the corrected engine torque, is set only by the converter torque F / F compensation, or is a preset fixed value. Furthermore, it may be an example in which the scene is discriminated where the amount of compensation of the converter torque F / B increases, and is limited only during scene discrimination.

In the embodiment, as the slip control of the lock-up clutch 20, an example is shown in which control for realizing the target driving force Fd ^* intended by the driver is performed. However, the slip control of the lock-up clutch may be an example in which the control is performed by determining the target slip rotation speed as described in the prior art publication.

In the embodiment, an example in which the lockup control device of the present invention is applied to an engine vehicle equipped with a belt type continuously variable transmission CVT as an automatic transmission is shown. However, the lock-up control device of the present invention may be applied to a vehicle equipped with a stepped transmission called step AT or a vehicle equipped with a continuously variable transmission with a sub-transmission as an automatic transmission. Further, the applied vehicle is not limited to an engine vehicle, and can be applied to a hybrid vehicle in which an engine and a motor are mounted on a traveling drive source, an electric vehicle in which a motor is mounted on a traveling drive source, and the like.

Claims (5)

1. A torque converter interposed between the traveling drive source and the speed change mechanism;
   A lock-up clutch that is provided in the torque converter and that directly connects the torque converter input shaft and the torque converter output shaft by fastening;
   A transmission controller that controls engagement / slip / release of the lock-up clutch, and
   A target lock is calculated by calculating a converter torque by feedforward compensation based on a target differential rotational speed and feedback compensation based on a differential rotational speed deviation in the transmission controller, and subtracting the converter torque from an input torque to the torque converter. Provide a lock-up control unit that performs slip control to obtain up torque,
   The lockup control unit applies a restriction to suppress a torque increase due to integration of the integral term to the converter torque feedback compensation amount calculated while including an integral term for the differential rotation speed deviation in the feedback compensation.
   Automatic transmission lockup control device.
2. In the automatic transmission lockup control device according to claim 1,
   The lockup control unit limits an increase in the calculated value of the converter torque feedback compensation calculated by the feedback compensation by an upper limit torque value,
   Torque that guarantees release of the lockup clutch in the slip release scene of the lockup clutch while urging the upper limit torque value to increase the target lockup torque in the slip engagement scene of the lockup clutch Set to value,
   Automatic transmission lockup control device.
3. In the automatic transmission lockup control device according to claim 2,
   The lockup control unit gives the upper limit torque value by an expression obtained by subtracting a converter torque feedforward compensation amount and a fixed value from an input torque to the torque converter,
   The fixed value is set to the minimum value among the torque values that can exceed the input torque to the torque converter in the sum of the converter torque feedforward compensation.
   Automatic transmission lockup control device.
4. In the automatic transmission lockup control device according to any one of claims 1 to 3,
   The lockup control unit converts a target driving force requested by the driver into a target driving source rotational speed of the traveling driving source,
   A feedforward compensator that performs feedforward compensation based on a target differential rotational speed that is a difference between the target drive source rotational speed and the turbine rotational speed;
   A feedback compensator that calculates an actual differential rotational speed due to a difference between the actual drive source rotational speed and the turbine rotational speed, and performs feedback compensation based on a differential rotational speed deviation that is a difference between the target differential rotational speed and the actual differential rotational speed; Having
   Automatic transmission lockup control device.
5. A lockup control method for an automatic transmission, comprising: a torque converter interposed between a driving source for traveling and a transmission mechanism; and a lockup clutch that directly connects a torque converter input shaft and a torque converter output shaft by fastening. There,
   When requesting slip engagement of the lock-up clutch,
   Calculate the converter torque feed forward compensation based on the target differential speed,
   Calculate the converter torque feedback compensation based on the differential speed deviation, and limit the feedback compensation so that it does not become excessive due to integration of the integral term,
   The converter torque is calculated from the converter torque feedback compensation and the converter torque feedback compensation,
   Calculate the input torque to the torque converter,
   Subtracting the converter torque from the input torque to calculate a target lockup torque,
   Supply lock-up hydraulic pressure according to this target lock-up torque,
   Automatic transmission lockup control method.

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