JPWO2020054269A1 - Automatic transmission lockup controller - Google Patents

Abstract

The lockup control device for the belt-type continuously variable transmission CVT according to the present invention includes a torque converter (2), a lockup clutch (20), and a CVT control unit (8). The CVT control unit (8) is obtained by feedback control based on the difference rotation speed deviation (δ) between the actual difference rotation speed (ΔN) and the target difference rotation speed (ΔN ^{*) when the lockup clutch (20) is requested to be completely engaged.} It has a lockup control unit (80) that outputs an indicated current (Alu) to obtain a target lockup torque (Tlu ^{*) to be obtained.} When the actual difference rotation speed (ΔN) becomes equal to or lower than the dead zone threshold value, the lockup control unit (80) adds a torque amount according to the variation in environmental factors of the torque converter (2) to the input torque (Tin). I do.

Description

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

Conventionally, there is known a lockup control device that feedback-controls the lockup differential pressure so that the actual difference rotation speed of the lockup clutch becomes the target difference rotation speed, and switches to feedforward control when the actual difference rotation speed becomes less than the set value. (See, for example, Patent Document 1).

In the above-mentioned conventional device, in order to improve the accuracy, it is considered to continue the feedback control until the lockup clutch is completely engaged. In that case, the target difference rotation speed is set to 0 rpm at the time of complete fastening. However, since the influence of the variation of the rotation sensor and the communication delay cannot be ignored in the vicinity of 0 rpm, even if the actual difference rotation speed is set to 0 rpm, the actual difference rotation speed is not completely reduced to 0 rpm, and the lockup clutch slips. There is a problem that the hydraulic oil deteriorates due to the heat generated by this slip.

The present invention has been made by paying attention to the above problems, and an object of the present invention is to prevent the lockup clutch from slipping in the vicinity of complete engagement while continuing feedback control when the lockup clutch is completely engaged. And.

International Publication Number WO 2017/068717 A1

In order to achieve the above object, the lockup control device for the automatic transmission of the present invention includes a torque converter, a lockup clutch, and a transmission controller.
Lockup control that outputs an instruction differential pressure to the transmission controller to obtain the target lockup torque obtained by feedback control based on the difference rotation speed deviation between the actual difference rotation speed and the target difference rotation speed when the lockup clutch is requested to be completely engaged. Provide a part.
When the actual difference rotation speed becomes equal to or less than the dead zone threshold value, the lockup control unit performs complete fastening control by adding the difference pressure amount according to the variation in the environmental factors of the torque converter to the indicated differential pressure.

In this way, when the actual difference rotation speed falls below the dead zone threshold value, the difference pressure component according to the variation in the environmental factors of the torque converter is added to the indicated differential pressure. As a result, when the lockup clutch is completely engaged, it is possible to prevent the lockup clutch from slipping in the vicinity of complete engagement while continuing feedback control.

FIG. 5 is an overall system diagram showing a drive system and a control system of an engine vehicle to which the lockup control device for the automatic transmission of the first embodiment is applied. It is a shift schedule diagram which shows an example of the D range stepless shift schedule used when the stepless shift control in an automatic shift mode is executed by a variator. It is a schematic block diagram which shows the lockup control device of Example 1. FIG. It is a block block diagram which shows each block which constitutes the lock-up control part of a CVT control unit. It is a detailed block diagram which shows the target calculation block, the torque capacity calculation block, and the realization block which constitute a lockup control part. It is a flowchart which shows the flow of the lockup control processing executed in the lockup control part of the CVT control unit of Example 1. FIG. It is a variation breakdown diagram which shows the breakdown of the total torque variation and the breakdown of the environmental factor variation. It is a comparative characteristic diagram which shows the comparison of (nominal engine torque characteristic), (nominal engine torque + offset torque characteristic), and (nominal engine torque × safety factor + offset torque characteristic) in relation to input torque with respect to engine rotation speed. It is a time chart which shows each characteristic in the uphill road driving scene where the complete fastening lockup control is performed.

Hereinafter, a mode for implementing the lockup control device for the automatic transmission of the present invention will be described with reference to the first embodiment shown in the drawings.

The lockup control device in the first embodiment is applied to an engine vehicle equipped with a belt-type continuously variable transmission (an example of an automatic transmission) composed of a torque converter, a forward / backward switching mechanism, a variator, and a final deceleration mechanism. be. Hereinafter, the configuration of the first embodiment will be described separately as "overall system configuration", "configuration of lockup control device", "detailed configuration of each block", and "lockup control processing configuration".

[Overall system configuration]
FIG. 1 shows a drive system and a control system of an engine vehicle to which the lockup control device for the automatic transmission of the first embodiment is applied. Hereinafter, the overall system configuration will be described 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 / backward switching mechanism 3, a variator 4, a final deceleration mechanism 5, and drive wheels 6 and 6. There is. Here, the belt-type continuously variable transmission CVT is configured by incorporating a torque converter 2, a forward / backward switching mechanism 3, a variator 4, and a final deceleration 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 controlling the output torque by operating the accelerator by the driver. The engine 1 has an output torque control actuator 10 that controls torque by opening / closing a throttle valve, cutting fuel, or the like. For example, fuel cut control is executed when the vehicle travels on the coast by releasing the accelerator foot.

The torque converter 2 is a starting element by a fluid coupling having a torque amplification function and a torque fluctuation absorption function. It has a lockup clutch 20 capable of directly connecting the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21 when the torque amplification function and the torque fluctuation absorption function are not required. The torque converter 2 includes a pump impeller 23, a turbine runner 24, and a stator 26 as components. The pump impeller 23 is connected to the engine output shaft 11 via a 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 a one-way clutch 25.

The forward / backward 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 / backward switching mechanism 3 includes a double pinion type planetary gear 30, a forward clutch 31 with a plurality of clutch plates, and a reverse brake 32 with a plurality of brake plates. The forward clutch 31 is hydraulically engaged by the forward clutch pressure Pfc when a forward traveling 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 steplessly changes the gear ratio (ratio of variator input rotation to variator output rotation) by changing the belt contact diameter. It has a shifting function. The primary pulley 42 is composed of a fixed pulley 42a and a slide pulley 42b arranged coaxially with the variator input shaft 40, and the slide pulley 42b slides by the primary pressure Ppri guided to the primary pressure chamber 45. The secondary pulley 43 is composed of a fixed pulley 43a and a slide pulley 43b arranged coaxially with the variator output shaft 41, and the slide pulley 43b slides by a secondary pressure Psec guided to the secondary pressure chamber 46. The pulley belt 44 is hung on a V-shaped sheave surface of the primary pulley 42 and a V-shaped sheave surface 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 punched plate material, and a large number of ring-shaped laminated rings are attached by sandwiching 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 connected 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, gives a differential function, and transmits the differential function to the left and right drive wheels 6 and 6. As a reduction gear mechanism, the final reduction gear 5 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 at the outer peripheral position of the differential case. It has a gear 55 and. Then, as the differential gear mechanism, there is a differential gear 56 interposed between the left and right drive shafts 51 and 51.

As shown in FIG. 1, the control system of the engine vehicle 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 capable of exchanging information with each other.

The hydraulic control unit 7 applies a primary pressure Ppri guided to the primary pressure chamber 45, a secondary pressure Psec guided to the secondary pressure chamber 46, a forward clutch pressure Pfc to the forward clutch 31, a 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 driving drive source for traveling, and a hydraulic control circuit 71 that regulates 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 adjusting operation according to a control command value (instructed 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. This line pressure PL is the original pressure when adjusting various control pressures, and is a hydraulic pressure that suppresses belt slippage and clutch slippage with respect to the torque transmitted to the drive system.

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

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

The lockup pressure solenoid valve 76 adjusts the pressure to the lockup hydraulic Pl that engages / slips / releases the lockup clutch 20 according to the indicated current Alu output from the CVT control unit 8.

The CVT control unit 8 performs line pressure control, shift control, forward / backward switching control, lockup control, and the like. In the line pressure control, a command value for obtaining a target line pressure according to the accelerator opening or the like is output to the line pressure solenoid valve 72. In shift control, when the target gear ratio (target primary rotation speed Npri ^* ) is determined, the command value for obtaining the determined target gear ratio (target primary rotation speed Npri ^* ) is output to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74. do. In the forward / backward switching control, a command value for controlling 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 instruction current Alu that controls the lockup hydraulic Plu that engages / engages / releases 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 from are input.

Sensor information from the engine rotation sensor 12, the accelerator opening sensor 14, and the like is input to the engine control unit 9. When the CVT control unit 8 requests the engine rotation information and the accelerator opening information from 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 the engine torque information is requested to the engine control unit 9, the information of the actual engine torque Te estimated and calculated in the engine control unit 9 is received via the CAN communication line 13.

FIG. 2 shows an example of a D-range continuously variable transmission schedule used when the variator 4 executes 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 and steplessly changed according to the driving state of the vehicle. The shift control in the "D range shift mode" is performed by the operating point on the D range continuously variable transmission 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 rotation speed Npri ^* . Then, the actual primary rotation speed Npri from the primary rotation sensor 90 is controlled by the pulley hydraulic control to match the ^{target primary rotation speed Npri *.}

That is, as shown in FIG. 2, the D-range continuously variable transmission schedule used in the "D-range continuously variable transmission mode" has a gear ratio range of the lowest gear ratio and the highest gear ratio according to the operating point (VSP, APO). It is set to change the gear ratio steplessly within the range. For example, when the vehicle speed VSP is constant, when the accelerator is depressed, the target primary speed Npri ^* rises and shifts in the downshift direction, and when the accelerator is returned, the target primary speed Npri ^* decreases and rises. Shift in the shift direction. When the accelerator opening APO is constant, the gear shifts in the upshift direction when the vehicle speed VSP increases, and shifts in the downshift direction when the vehicle speed VSP decreases.

[Lockup controller configuration]
FIG. 3 shows the lockup control device of the first embodiment. Hereinafter, the outline configuration of the lockup control device will be described with reference to FIG. The lockup is abbreviated as "LU", the feedforward is abbreviated as "F / F", and the 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 / backward switching mechanism 3, and a variator 4 (a variator 4). A transmission mechanism), a final deceleration mechanism 5, and a drive wheel 6.

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 sets 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 drive wheels 6 becomes the target driving force Fd ^*. It is characterized in that 20 slip controls are performed. At that time, the target driving force Fd ^* is converted to the target engine speed Ne ^{* in order to improve the controllability in slip control.} The converter torque Tcnv is calculated by executing the control (F / F control + F / B control) that converges the actual engine speed Ne to the target engine speed Ne ^*. Then, as shown in FIG. 3, the input torque Tin input from the engine 1 to the torque converter 2 holds the relational expression of Tin = Tcnv + Tlu. ^{Therefore, the target LU torque Tlu *} of the lockup clutch 20 is calculated by calculating the input torque Tin and the converter torque Tcnv, and the ^{indicated current Alu for obtaining the target LU torque Tlu *} is output to the lockup pressure solenoid valve 76. By performing slip control (torque ratio control of the torque converter 2) so as to obtain the target engine rotation speed Ne ^{* in this way, the target driving force Fd * intended by the driver is performed during the slip control of the lockup clutch 20.} Can be realized.

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.

As shown in FIG. 4, 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 a realization block 85.

^{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 rotation speed Ne ^* using all engine performance characteristics. , Calculate the profile of the target engine speed Ne ^*. Then, while 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, while the lockup clutch 20 is completely engaged, the release request flag is output when the profile ^{of the target engine speed Ne * is realized by the clutch slip control.}

The request arbitration block 82 inputs the conclusion request flag and the release request flag from the driving force demand block 81, calculates the lockup request from various requests, arbitrates the requests, and determines 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. There are requests, etc.

The target calculation block 83 inputs the immediate release request flag, the release request flag, the slip request flag, and the conclusion request flag from the request arbitration block 82, and calculates the difference rotation speed target ΔN ^* from these LU requests. Here, the difference rotation speed target ΔN ^* includes an immediate release difference rotation speed target, a release difference rotation speed target, a slip difference rotation speed target, and a fastening difference rotation speed target. The target calculation block 83 inputs ^{the target engine speed Ne *} calculated by the driving force demand block 81.

The torque capacity calculation block 84 ^{inputs the target difference 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 indicated torque (target LU torque Tlu ^* ) that ^{realizes the target difference rotation speed ΔN *} is calculated by the engine torque calculation (input torque Tin calculation) and the converter torque Tcnv calculation (F / F control + F / B control). ..

^{The realization block 85 inputs the target LU torque Tlu *} from the torque capacity calculation block 84, converts the target lockup torque Tlu ^* into the lockup hydraulic Pl, and further converts the lockup hydraulic Pl into the indicated current Alu.

[Detailed configuration of each block]
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. Hereinafter, the detailed configuration of each block 83, 84, 85 will be described with reference to FIG.

The target calculation block 83 has a look-ahead turbine speed calculator 83a and a first differencer 83b.

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

^{The first differentialr 83b calculates the target difference rotation speed ΔN *} from the ^{difference between the target engine rotation speed Ne *} calculated by the driving force demand block 81 and the look-ahead turbine rotation speed Ntpre calculated by the look-ahead turbine rotation speed calculator 83a. do.

The torque capacity calculation block 84 includes an engine torque calculation area 841, a converter torque calculation area 842, and a fifth differential device 84k.

The engine torque calculation area 841 includes an engine torque multiplier 84a, a first adder 84b, a selector 84c, and a second diff device 84d.

The engine torque multiplier 84a calculates the engine torque Te1 that absorbs the variation of the engine torque Te at the time of complete fastening control by multiplying the engine torque Te and the torque safety factor. Information on the current engine torque Te is obtained from the engine control unit 9.

The first adder 84b adds the engine torque Te1 from the engine torque multiplier 84a and the offset torque (fixed value) to absorb the engine torque that absorbs the hydraulic variation and other variations due to the variation of the rotation sensor. Calculate Te2.

The selector 84c inputs the complete engagement control permission flag, selects the engine torque Te as the calculation engine torque Tec when the complete engagement control permission flag = 0, and the calculation engine when the complete engagement control permission flag = 1. Select engine torque Te2 as torque Tec.

The second differencer 84d calculates the input torque Tin (= Tec−Ti−To) by subtracting the inertial shuttle torque Ti and the oil pump loss torque To from the calculation engine torque Tec selected by the selector 84c.

The converter torque calculation area 842 includes an F / F compensator 84e, a third diff, 84f, a fourth diff 84g, an F / B compensator 84h, a minimum value selector 84i, and a second adder 84j. Has.

^{The F / F compensator 84e inputs the target difference rotation speed ΔN *} (= target slip rotation speed) from the first differentialr 83b, and sets the converter torque F / F compensation Tcnv_ff according ^{to the target difference rotation speed ΔN *.} calculate. For example, in the case of complete fastening control, the converter torque F / F compensation Tcnv_ff for converging ^{the target difference rotation speed ΔN * to the fastening difference rotation speed target is calculated.}

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

The fourth differentialr 84g inputs the target difference rotation speed ΔN ^* (= target slip rotation speed) from the first differentialr 83b and the actual difference rotation speed ΔN (= actual slip rotation speed) from the third differentialr 84f. do. Then, the difference rotation speed deviation δ is calculated from the difference between the target difference rotation speed ΔN ^{* and the actual difference rotation speed ΔN.}

The F / B compensator 84h inputs the difference rotation speed deviation δ from the fourth differencer 84g, and controls the converter torque F / B compensation amount calculation value Tcnv_fb (c) according to the difference rotation speed deviation δ by PI feedback. Calculated by (P: proportional, I: integral). When the F / B compensator 84h receives a coast slip request due to the establishment of the coast slip control start condition in the request arbitration block 82, the converter torque F / B compensation calculation value Tcnv_fb (c) up to that point is initially reset. Reset to value.

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 ＝ Tin−Tcnv_ff−K (K: fixed value)… (1)
It is given by the equation (1) expressed by, that is, the variable torque value according to the input torque Tin and the converter torque F / F compensation Tcnv_ff. The fixed value K is set to be the upper limit torque value Tcnv_max that promotes an increase ^{in the target LU torque Tlu *} during the slip engagement scene of the lockup clutch 20.

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 fifth differencer 84k is provided outside the engine torque calculation area 841 and the converter torque calculation area 842. ^{The fifth differencer 84k calculates the target LU torque Tlu *} by subtracting the input torque Tin from the second differencer 84d and the converter torque Tcnv from the second adder 84j.

The realization block 85 has a torque-to-hydraulic converter 85a and a hydraulic-to-current converter 85b. The torque → hydraulic converter 85a converts the target LU torque Tlu ^* input from the torque capacity calculation block 84 into the LU hydraulic Pl. The hydraulic-to-current converter 85b converts the LU hydraulic Plu input from the torque-to-hydraulic converter 85a into the indicated current Alu.

[Lockup control processing configuration]
FIG. 6 shows the flow of the lockup control process executed by the lockup control unit 80 of the CVT control unit 8 of the first embodiment. Hereinafter, each step of FIG. 6 will be described. In the initial setting, the complete fastening control permission flag = 0.

In step S1, following the start, the clearing of the timer value in S5, or the determination that the timer value <predetermined value in S7, the normal lockup control is executed, and the process proceeds to step S2.

Here, the normal lockup control refers to the lockup control in which the complete engagement control permission flag = 0 and the input torque Tin is calculated by subtracting the inner shuttle torque Ti and the oil pump loss torque To from the engine torque Te. ..

In step S2, following the execution of the normal lockup control in S1, ^{it is determined whether or not the target difference rotation speed ΔN *} is equal to or less than the engagement difference rotation speed target. If YES (target difference rotation speed ΔN ^* ≤ fastening difference rotation speed target), the process proceeds to step S3, and if NO (target difference rotation speed ΔN ^* > fastening difference rotation speed target), the process proceeds to step S5.

^{Here, the "engagement difference rotation speed target" is the achievement target of the target difference rotation speed ΔN *} in the feed forward compensation when there is a complete engagement request for the lockup clutch 20, and 0 <fastening difference rotation speed target <dead zone. Set to the threshold.

In step S3, following the determination that the target difference rotation speed ΔN ^* ≦ the fastening difference rotation speed target in S2, it is determined whether or not the actual difference rotation speed ΔN is equal to or less than the dead zone threshold value. If YES (actual difference rotation speed ΔN ≤ dead zone threshold value), the process proceeds to step S4, and if NO (actual difference rotation speed ΔN> dead zone threshold value), the process proceeds to step S5.

Here, the "dead zone threshold value" is a low rotation speed range of the actual difference rotation speed ΔN calculated based on the rotation sensor information, and is set to a difference rotation value in the lower limit range where the detection accuracy by the rotation sensor can be ensured. NS. The actual difference rotation speed ΔN is calculated by using the engine rotation speed Ne from the engine rotation sensor 12 and the secondary rotation speed Nsec from the secondary rotation sensor 97.

In step S4, following the determination that the actual difference rotation speed ΔN ≦ the dead zone threshold value in S3, it is determined whether or not the state is in the coast state. If YES (not in the coast state), the process proceeds to step S6, and if NO (in the coast state), the process proceeds to step S5.

For example, when the idle flag = 0, it is determined that the state is not in the coast state, and when the idle flag = 1, it is determined that the state is in the coast state. The term "not in the coast state" means a driving running state by depressing the accelerator, and the "coast state" means a coasting running state by releasing the accelerator foot.

^{In step S5, it is determined that the target difference rotation speed ΔN *} in S2 is the target difference rotation speed, or the actual difference rotation speed ΔN in S3 is the dead zone threshold, or the coast in S4. Following the determination of the state, the timer value is cleared, and the process returns to step S1.

In step S6, following the determination that the coast state is not in S4, the timer value is counted and the process proceeds to step S7.

In step S7, following the counting of the timer value in S6, it is determined whether or not the timer value is equal to or greater than a predetermined value. If YES (timer value ≥ predetermined value), the process proceeds to step S8, and if NO (timer value <predetermined value), the process returns to step S1.

Here, the "predetermined value" is set as a determination time during which the control start condition by S2, S3, and S4 continues to be satisfied when the complete engagement control for gripping the lockup clutch 20 is permitted.

In step S8, following the determination that the timer value ≥ the predetermined value in S7, the complete engagement control permission flag is set to the complete engagement control permission flag = 1, and the process proceeds to step S9.

In step S9, following the determination that the complete engagement control permission flag = 1 in S8 and the release condition not being satisfied in S10, the complete engagement lockup control is executed, and the process proceeds to step S10.

Here, the complete engagement lockup control is a lockup in which the complete engagement control permission flag = 1 and the input torque Tin is calculated by subtracting the inner shuttle torque Ti and the oil pump loss torque To from the engine torque Te2 (> Te). It refers to control.

In step S10, following the execution of the complete engagement lockup control in S9, it is determined whether or not the release condition of the complete engagement lockup control is satisfied. If YES (the cancellation condition is satisfied), the process proceeds to step S11, and if NO (the cancellation condition is not satisfied), the process returns to step S9.

Here, the "condition for releasing the complete engagement lockup control" is one of the target difference rotation speed ΔN ^* > the engagement difference rotation speed target, while the start condition for the complete engagement lockup control is given under three conditions. Given only by condition.

In step S11, following the determination that the release condition is satisfied in S10, the complete engagement control permission flag is reset from the complete engagement control permission flag = 1 to the complete engagement control permission flag = 0, and the process proceeds to return.

Next, the operation of the first embodiment will be described separately for "current lockup control problem", "problem solving measure", "input torque correction amount setting action", and "complete fastening lockup control action".

[Current issues of lockup control]
The current lockup control is based on the target difference rotation speed, compares it with the actual difference rotation speed, controls the difference rotation speed F / B, calculates the target LU torque, and converts the target LU torque into an LU differential pressure instruction. I'm doing it. For the complete engagement of the lockup clutch, the target difference rotation speed is set to "0", and the LU capacity is barely reached with respect to the input torque. However, the current lockup control has the following problems.

(a) In the case of F / B control in which the difference rotation speed is 0 rpm when the complete LU is fastened, the difference rotation speed = 0 rpm is not guaranteed. That is, although the control is performed at the target difference rotation speed of 0 rpm in the steady state, the actual difference rotation speed does not completely reach 0 rpm due to the variation of the rotation sensor and the communication delay. Then, when the number of revolutions falls below a certain difference, the F / B control is stopped. Therefore, in the dead zone region of the difference rotation speed at which the F / B control is stopped, there is a high possibility that the lockup clutch slips slightly.

(b) No safety factor is provided for input torque fluctuations on the drive side (engine torque variations, inertia, etc.). Therefore, if the input torque fluctuates due to the variation in the engine torque, there is a concern that a minute slip may occur in the lockup clutch due to the response delay of the hydraulic F / B control.

As described above, the current differential rotation speed F / B control allows frequent occurrence of slip in the completely engaged region when the lockup clutch is required to be completely engaged. As a result, the transmission fluid (ATF) is oxidized due to the temperature around the friction material rising due to the heat generated by the slip. Impurities are generated when the transmission hydraulic oil is oxidized. When impurities are generated, the friction material is clogged, the μ-V characteristics of the friction material are changed, and judder is likely to occur.

[Problem solving measures]
In response to the above-mentioned problems of lockup control in the present situation, the present inventors focused on the “variation” of the lockup unit and analyzed the breakdown of the torque variation.

As shown in FIG. 7, the overall torque variation is represented by the sum of the individual unit variation and the environmental factor variation. Of these, the "unit individual variation" is absorbed by the difference rotation speed F / B control, so it is not necessary to correct for the unit individual variation. However, since "environmental factor variation" is not absorbed by the difference rotation speed F / B control, it is necessary to quantify and correct the variation.

Therefore, as a solution to the problem, the CVT control unit 8 can be obtained by F / B control based on the difference rotation speed deviation δ between ^{the actual difference rotation speed ΔN and the target difference rotation speed ΔN * when the lockup clutch 20 is requested to be completely engaged.} A lockup control unit 80 is provided to output an indicated differential pressure (LU hydraulic ^Pl) to obtain a target lockup torque Tlu *. When the actual difference rotation speed ΔN becomes equal to or less than the dead zone threshold value, the lockup control unit 80 is a measure for performing complete engagement control by adding a differential pressure component according to the variation in environmental factors of the torque converter 2 to the indicated differential pressure (LU hydraulic Plu). It was adopted.

That is, when three start conditions based on the target difference rotation speed condition, the actual difference rotation speed condition, and the drive state condition are satisfied during the normal lockup control with a complete fastening request, S1 → S2 → S3 → S4 in the flowchart of FIG. → S6 → S7. Then, while it is determined in S7 that the timer value <predetermined value, the flow of proceeding from S1 → S2 → S3 → S4 → S6 → S7 is repeated.

Then, when the state in which the three start conditions are satisfied continues and it is determined in S7 that the timer value ≥ the predetermined value, the process proceeds from S7 to S8 → S9 → S10, and the complete engagement control permission flag is set in S8. Then, while it is determined in S10 that the release condition is not satisfied, the flow from S9 to S10 is repeated, and in S9, the torque amount corresponding to the variation in the environmental factors of the torque converter 2 is added to the ^{target lockup torque Tlu *.} Full engagement lockup control is performed.

In this way, when the actual difference rotation speed ΔN falls below the dead zone threshold value, the torque amount corresponding to the variation in environmental factors of the torque converter 2 is added to ^{the target lockup torque Tlu *.} Therefore, when the lockup clutch 20 is completely engaged, it is possible to prevent the lockup clutch 20 from slipping in the vicinity of the complete engagement while continuing the F / B control.

Therefore, the transmission fluid (ATF) is not oxidized due to the temperature around the friction material rising due to the slip heat generated by the lockup clutch 20, and the friction material is not clogged due to the generation of impurities. As a result, it is possible to prevent the μ-V characteristics of the friction material from changing and judder from easily occurring.

[Input torque correction amount setting action]
Further analysis of the breakdown of "environmental factor variations" shows that, as shown in Fig. 7, engine torque variations and other variations (LU hydraulic pressure, O / P loss torque, SSG, inertia, rotation sensor, etc.) It is expressed in Japanese.

When considering measures against "environmental factor variations", as a simple measure, "environmental factor variations" are regarded as one variation, and the variation is offset-corrected. In this case, the offset correction amount does not reflect the torque variation of the engine, which has a proportional relationship with the magnitude of the engine torque.

For example, assuming that the "environmental factor variation" is the maximum value of the hydraulic variation (including the engine torque variation), the input torque characteristic Tin (A) due to the engine torque (nominal value) is shown in FIG. The lockup torque will be higher by the amount of offset correction. In this case, since the offset correction amount is given as a fixed value, if the fluctuation of the engine torque is large, the maximum value of the hydraulic variation will be exceeded, and there remains a concern that the lockup clutch may slip in the completely engaged region.

On the other hand, the two variations based on the breakdown analysis of the variations in environmental factors differ in the content of the variations as follows.
(a) Since the torque variation of the engine 1 has a proportional relationship with the engine torque Te, the gain should be corrected by the torque safety factor.
(b) Other variations (LU hydraulic pressure, O / P loss torque, SSG, inertia, rotation sensor, etc.) should be offset-corrected because the gain relationship is small.

Therefore, regarding the "environmental factor variation", the measure is to add the gain correction for the engine torque variation and the offset correction for the variation other than the engine torque variation.

As described above, when the "environmental factor variation" is given by the sum of the engine torque variation due to the gain correction and the other variation due to the offset correction, it is shown in the input torque characteristic Tin (C) of FIG. In other words, the input torque characteristic Tin (C) has a lockup torque that is slightly higher than the input torque characteristic Tin (B), and it reflects the engine torque variation and has a variable correction amount according to the magnitude of the engine torque. Become. Therefore, even if the engine torque increases due to the accelerator depression operation or the like in the completely engaged region, the additional correction amount for the "environmental factor variation" becomes appropriate, and the lockup clutch 20 slips. Is effectively suppressed.

[Complete fastening lockup control action]
FIG. 9 shows each characteristic in the uphill road driving scene where the complete fastening lockup control is performed. Hereinafter, the complete fastening lockup control action will be described with reference to FIG.

At the start of uphill driving, if the brake is turned off at time t1 and the accelerator is turned on at time t2 immediately after that, a complete engagement request is issued at time t2.

Therefore, the engagement control of the lockup clutch 20, which has been released until then, is started from the time t2. The initial start-up of the LU hydraulic LUPRS (= Plu) is started, and the LU hydraulic LUPRS is increased as the ^{target LU torque LUTRQTGT (= target LU torque Tlu *) increases as the engine torque ENGTRQ (= Te) increases.} Control is executed.

At time t3, the start condition of complete fastening control that the target difference rotation speed ΔN ^* ≤ fastening difference rotation speed target, the actual difference rotation speed ΔN ≤ dead zone threshold, and the non-coast state is satisfied is satisfied, and from time t3. When the predetermined time elapses at time t4, the complete fastening control is started.

In other words, from time t4 to time t5 when the condition for releasing the complete engagement control is satisfied, the corrected LU torque is added to the target LU torque LUTRQTGT regardless of the fluctuation of the actual slip rotation speed SlipREV (= actual difference rotation speed). The corrected LU hydraulic component is added to the LU hydraulic LUPRS.

When the target difference rotation speed ΔN ^* is switched from the fastening difference rotation speed target to the slip difference rotation speed target ^{immediately before time t5, at time t5, the target difference rotation speed ΔN *} > fastening difference rotation speed target becomes complete. The condition for releasing the fastening control is satisfied. When the release condition of the complete engagement control is satisfied, the corrected LU torque and the corrected LU oil pressure are added to zero, and the target LU torque is achieved by feedforward compensation and feedback compensation that match the actual slip rotation speed SlipREV with the target slip rotation speed. LUTRQTGT and LU hydraulic LUPRS are controlled.

The actual slip rotation speed SlipREV approaches the target slip rotation speed at time t6, the actual slip rotation speed SlipREV approaches the target slip rotation speed at time t7, and the actual slip rotation speed SlipREV approaches the target slip rotation speed at time t7. Matches. Therefore, after the time t7, the slip control of the lockup clutch 20 is maintained so that the traveling driving force on the uphill road is output.

In this way, the engagement control of the lockup clutch 20 following the input torque Tin is executed from the F / B control while the actual difference rotation speed until the lockup clutch 20 reaches the complete engagement range> the dead zone threshold value. .. In this way, by controlling the actual difference rotation speed F / B, it is possible to absorb the variation of individual units, and also to obtain the variation of LU torque and the variation of hydraulic pressure.

When the lockup clutch 20 reaches the complete engagement region, the actual difference rotation speed> the dead zone threshold value, and the complete engagement control is started, the input torque heap is executed by adding the torque amount of the environmental factor variation to the input torque Tin. Therefore, as shown in the in-frame characteristic of the arrow A in FIG. 9, the engine speed Ne and the turbine speed Nt match, and the lockup clutch 20 eliminates the minute slip. Therefore, it is possible to eliminate an unintended slip of the lockup clutch 20 in a scene of traveling on an uphill road due to an accelerator depression operation or a torque sudden increase scene such as an accelerator depression as shown in FIG.

As described above, the lock-up control device for the belt-type continuously variable transmission CVT of the first embodiment has the effects listed below.

(1) A torque converter 2 interposed between the driving drive source (engine 1) and the transmission mechanism (variator 4), and
A lockup clutch 20 that is provided in the torque converter 2 and directly connects the torque converter input shaft and the torque converter output shaft by fastening.
It is equipped with a transmission controller (CVT control unit 8) that controls engagement / slip / release of the lockup clutch 20.
When the transmission controller (CVT control unit 8) is requested to completely engage the lockup clutch 20, the target lockup torque obtained by feedback control based on the difference rotation speed deviation δ between ^{the actual difference rotation speed ΔN and the target difference rotation speed ΔN *.} A lockup control unit 80 is provided to output the indicated differential pressure (LU hydraulic Plu) to obtain ^{Tlu *.}
When the actual difference rotation speed ΔN becomes equal to or less than the dead zone threshold value, the lockup control unit 80 completely adds a differential pressure component (torque component) according to the variation in environmental factors of the torque converter 2 to the indicated differential pressure (input torque Tin). Performs fastening control.
Therefore, when the lockup clutch 20 is completely engaged, it is possible to prevent the lockup clutch 20 from slipping in the vicinity of the complete engagement while continuing the feedback control.
That is, when the actual difference rotation speed Δn falls below the dead zone threshold value, the differential pressure component (torque component) according to the variation in environmental factors of the torque converter 2 is added to the indicated differential pressure (input torque Tin).

(2) The lockup control unit 80 determines the variation in environmental factors as the driving source torque variation (engine torque variation) proportional to the traveling drive source torque (engine torque) of the traveling drive source (engine 1) and others. Divided into variations
The differential pressure according to the variation of environmental factors is given as the offset value of the driving source torque variation (engine torque variation) obtained by multiplying the driving drive source torque (engine torque) by the safety factor. Sum with minutes.
For this reason, in complete fastening control, the differential pressure (torque) added according to the variation in environmental factors depends on the drive source torque variation (engine torque variation) in proportion to the driving drive source torque (engine torque). Can be given appropriately.
That is, when all the differential pressure components to be added according to the variation of environmental factors are given as offset values, there is a concern that the additional differential pressure components will be insufficient when the driving drive source torque (engine torque) for traveling increases. On the other hand, the gain correction of the driving drive source torque (engine torque) for traveling eliminates the shortage of the additional differential pressure.

(3) The lockup control unit 80 calculates the input torque Tin to the torque converter 2, and calculates the ^{converter torque Tcnv by feed-forward compensation based on the target difference rotation speed ΔN *} and feedback compensation based on the difference rotation speed deviation δ. Outputs the indicated differential pressure (LU hydraulic ^Pl) to obtain the target lockup torque Tlu *, which is calculated by subtracting the converter torque Tcnv from the input torque Tin.
The differential pressure component according to the variation in the environmental factors of the torque converter 2 is added as the torque component according to the variation in the environmental factors when calculating the input torque Tin to the torque converter 2.
^{For this reason, in complete fastening control, it is possible to reflect the accurate additional torque in the target lockup torque Tlu *} , indicated differential pressure (LU hydraulic Plu), and indicated current Alu as the additional amount according to the variation in environmental factors. can.
That is, the additional amount according to the variation of environmental factors can be added to the target lockup torque Tlu ^* , the indicated differential pressure (LU hydraulic Pl), and the indicated current Alu of the result system. However, the additional amount itself according to the variation in environmental factors includes the variation in the drive source torque for travel (engine torque variation) obtained by multiplying the drive source torque for travel (engine torque) by the safety factor. Therefore, in the calculation of the input torque Tin to the torque converter 2 that handles the driving drive source torque (engine torque), it is possible to add the torque amount with high accuracy by adding the torque amount according to the variation of environmental factors. ..

(4) The lockup control unit 80 ^{converts the target driving force Fd *} required by the driver into the target drive source speed (target engine speed Ne ^* ) of the driving drive source (engine 1).
^{The target difference rotation speed ΔN *} , which is the input information of the feed forward compensation, is calculated by the difference between the target drive source rotation speed (target engine rotation speed Ne ^* ) and the turbine rotation speed Nt.
The feedforward compensation in the complete engagement control controls the target difference rotation speed ΔN ^* to converge to the engagement difference rotation speed target when the lockup clutch 20 is requested to be completely engaged.
Therefore, when a complete engagement is requested from the release of the lockup clutch 20, the target driving force Fd ^* intended by the driver can be realized during the slip control from the start of engagement to the complete engagement region.
That is, when a complete engagement request is made from the release of the lockup clutch 20, lockup control based on a driving force demand is executed during slip control from the start of engagement to the complete engagement region.

(5) The lockup control unit 80 determines that the start condition of the complete fastening control is that the target difference rotation speed ΔN ^* is less than or equal to the fastening difference rotation speed target, the actual difference rotation speed ΔN is less than or equal to the dead zone threshold value, and the vehicle runs on a non-coast. Give depending on the conditions.
Therefore, it is possible to prevent the lockup clutch 20 from slipping unintentionally in a scene where the input torque suddenly increases, such as when the lockup clutch 20 is completely engaged and the accelerator is stepped on.

(6) The lockup control unit 80 gives the release condition of the complete fastening control only on the condition that the target difference rotation speed ΔN ^* exceeds the fastening difference rotation speed target.

Therefore, it is possible to prevent the lockup clutch 20 from slipping when there is an input torque Tin in which the actual difference rotation speed ΔN exceeds the dead zone threshold value after the lockup clutch 20 is completely engaged. Even if the lock-up clutch 20 is completely engaged and then the drive running state is changed to the coast running state, it is possible to prevent the lock-up clutch 20 from slipping due to a torque change in which the input torque Tin straddles zero torque. .. As described above, among the start conditions, the condition that the actual difference rotation speed ΔN exceeds the dead zone threshold value and the condition that the transition to the coast running are not included in the release condition. That is, after the lockup clutch 20 is in the fully engaged state, even if the kickdown operation intervenes, the spike torque is input, or the coast running state is entered, the fully engaged state is not maintained and the vehicle does not want to slip. Because there is a request.

The lockup control device for the automatic transmission of the present invention has been described above based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and design changes and additions are permitted as long as the gist of the invention according to each claim is not deviated from the claims.

In the first embodiment, as the lockup control unit 80, when the actual difference rotation speed ΔN becomes equal to or less than the dead zone threshold value, complete engagement control is performed in which a torque amount corresponding to the variation in environmental factors of the torque converter 2 is added to the “input torque Tin”. An example of doing this is shown. However, the lockup control unit may be an example of performing complete engagement control in which a torque amount corresponding to the variation in environmental factors of the torque converter 2 is added to ^{the “target lockup torque Tlu *”.} Further, it may be an example of performing complete fastening control in which a differential pressure component according to the variation in environmental factors of the torque converter 2 is added to the "LU hydraulic Pl". Further, it may be an example of performing complete fastening control in which the indicated current amount according to the variation in the environmental factors of the torque converter 2 is added to the "instructed current Alu".

In the first embodiment, as the slip control of the lockup clutch 20, an example of controlling to realize the ^{target driving force Fd * intended by the driver is shown.} However, as the slip control of the lockup clutch, as described in the prior art publication, there may be an example in which the target slip rotation speed is determined and the feedback control is performed.

In the first embodiment, an example is shown 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. However, the lockup control device of the present invention may be applied as an automatic transmission to a vehicle equipped with a stepped transmission called a step AT, a vehicle equipped with a continuously variable transmission with an auxiliary transmission, or the like. Further, the applicable vehicle is not limited to an engine vehicle, but can also be applied to a hybrid vehicle in which an engine and a motor are mounted as a driving drive source, an electric vehicle in which a motor is mounted as a driving drive source, and the like.

Claims (6)

A torque converter installed between the driving drive source and the transmission mechanism,
A lockup clutch that is provided in the torque converter and 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 lockup clutch is provided.
A lock that outputs an instruction differential pressure to the transmission controller to obtain a target lockup torque obtained by feedback control based on the difference rotation speed deviation between the actual difference rotation speed and the target difference rotation speed when the lockup clutch is requested to be completely engaged. Up control unit is provided
When the actual difference rotation speed becomes equal to or less than the dead zone threshold value, the lockup control unit performs complete fastening control by adding a difference pressure component according to the variation in environmental factors of the torque converter to the indicated differential pressure.
Lock-up control device for automatic transmissions. In the lockup control device for the automatic transmission according to claim 1.
The lockup control unit divides the variation in environmental factors into a variation in the torque of the drive source for travel, which is proportional to the torque of the drive source for travel in the drive source for travel, and another variation.
The differential pressure component according to the variation in environmental factors is the sum of the drive source torque variation for travel obtained by multiplying the drive source torque for travel by a safety factor and the other variation given as an offset value.
Lock-up control device for automatic transmissions. In the lockup control device for the automatic transmission according to claim 2.
The lockup control unit calculates the input torque to the torque converter, calculates the converter torque by the feed forward compensation based on the target difference rotation speed and the feedback compensation based on the difference rotation speed deviation, and calculates the converter torque from the input torque. Output the indicated differential pressure to obtain the target lockup torque calculated by subtracting the converter torque.
The differential pressure component according to the variation in the environmental factors of the torque converter is added as the torque component according to the variation in the environmental factors when calculating the input torque to the torque converter.
Lock-up control device for automatic transmissions. In the lockup control device for the automatic transmission according to claim 3.
The lockup control unit converts the target driving force required by the driver into the target driving source rotation speed of the traveling drive source, and converts the target driving force into the target driving source rotation speed of the traveling drive source.
The target difference rotation speed, which is the input information of the feed forward compensation, is calculated by the difference between the target drive source rotation speed and the turbine rotation speed.
The feedforward compensation in the complete engagement control controls the target difference rotation speed to converge to the engagement difference rotation speed target when the lockup clutch is requested to be completely engaged.
Lock-up control device for automatic transmissions. In the lockup control device for the automatic transmission according to claim 4.
The lockup control unit sets the start condition of the complete fastening control on the condition that the target difference rotation speed is equal to or less than the fastening difference rotation speed target, the actual difference rotation speed is equal to or less than the dead zone threshold value, and the non-coast running. give,
Lock-up control device for automatic transmissions. In the lockup control device for the automatic transmission according to claim 5.
The lockup control unit gives the release condition of the complete fastening control only by the condition that the target difference rotation speed exceeds the fastening difference rotation speed target.
Lock-up control device for automatic transmissions.

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