WO2019221066A1

WO2019221066A1 - Lock-up control device for automatic transmission

Info

Publication number: WO2019221066A1
Application number: PCT/JP2019/018961
Authority: WO
Inventors: 旭明王; 直泰池田
Original assignee: ジヤトコ株式会社; 日産自動車株式会社
Priority date: 2018-05-14
Filing date: 2019-05-13
Publication date: 2019-11-21
Also published as: JP7057825B2; JPWO2019221066A1

Abstract

A lock-up control device for a belt-type continuously variable transmission (CVT) is equipped with a torque converter (2), a lock-up clutch (20), and a CVT control unit (8). The CVT control unit (8) is provided with a coast slip control unit (80a) which feedback-controls the lock-up differential pressure in a manner such that the actual slip rotation speed converges on a target coast slip rotation speed during a coasting deceleration in which the foot is taken off the accelerator. The coast slip control unit (80a) calculates the target coast slip rotation speed to be used in the feedback control on the basis of the anticipated vehicle deceleration.

Description

Automatic transmission lockup control device

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

2. Description of the Related Art Conventionally, there is known an automatic transmission for a vehicle that can prevent engine stall while maintaining lockup as low as possible, and reduce shock when releasing the lockup clutch. In this conventional apparatus, when decelerating, the fast-release lockup-off vehicle speed Vs is calculated a predetermined time before the expected arrival of the lockup-off vehicle speed that is equal to or lower than the lockup-off vehicle speed obtained from the deceleration α when the vehicle speed V is detected. To do. When the detected vehicle speed V reaches the fast-release lockup-off vehicle speed Vs, lock-up off control is started, and the lock-up off control determines the lockup on pressure Pon according to the fast-release lockup off vehicle speed Vs. The pressure is immediately reduced to the set initial pressure Ps. Subsequently, the pressure is gradually reduced with a pressure reduction gradient β set in accordance with at least the deceleration α when the vehicle speed is detected, and when the detected vehicle speed V reaches the lockup-off vehicle speed Vo, the pressure is reduced to the lockup-off pressure Poff at once ( For example, see Patent Document 1).

JP 2012-47312A

In the above-described conventional device, when releasing the lock-up clutch, the lock-up control is performed by feed-forward control according to the differential pressure characteristic set according to the vehicle deceleration at the start of control. For this reason, there is a problem that deviation of the actual differential pressure with respect to the differential pressure characteristic after the start of the lock-up control is allowed, and the release timing of the lock-up clutch may deviate from a desired timing.

The present invention has been made paying attention to the above problem, and an object of the present invention is to suppress a lockup release timing from deviating from a desired timing while suppressing a response delay due to feedback control during coast slip deceleration.

In order to achieve the above object, a lockup control device for an automatic transmission according to the present invention includes a torque converter, a lockup clutch, and a lockup controller.
The lock-up controller is provided with a coast slip control unit that feedback-controls the lock-up differential pressure so that the actual coast slip rotational speed converges to the target coast slip rotational speed during coast deceleration by the accelerator release operation.
The coast slip control unit calculates a target coast slip rotational speed used in feedback control based on the look-ahead deceleration of the vehicle.

In this way, by calculating the target coast slip rotation speed using the look-ahead deceleration of the vehicle, it is possible to suppress the lockup release timing from deviating from the desired timing while suppressing the response delay due to feedback control during coast slip deceleration. can do.

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 a first 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 Example 1. FIG. 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 the coast slip control part which has a lockup control part. It is a flowchart which shows the flow of the coast slip control process performed in the coast slip control part of the CVT control unit of Example 1. FIG. It is a flowchart which shows the flow of the lockup clutch torque capacity control processing performed in the coast slip control part of the CVT control unit of Example 1. It is a time chart which shows each characteristic of vehicle speed, target coast slip number of rotations, and LU indication pressure in a coast deceleration scene where vehicle deceleration differs.

Hereinafter, a mode for carrying out a lockup control device for an automatic transmission according to the present invention will be described based on Example 1 shown in the drawings.

The lockup control device according to the first embodiment is applied to an engine vehicle equipped with a belt-type continuously variable transmission (an example of an automatic transmission) including a torque converter, a forward / reverse switching mechanism, a variator, and a final reduction mechanism. is there. Hereinafter, the configuration of the first embodiment is changed to “overall system configuration”, “configuration of lockup control device”, “detailed configuration of torque capacity calculation block,” “coast slip control processing configuration”, “lockup clutch torque capacity control”. The processing will be described separately.

[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 a first 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. When the torque increasing function and the torque fluctuation absorbing function are not required, the lockup clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21 is provided. 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 that are arranged coaxially with 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, etc. 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 the LU command 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 speed 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 lock-up control, the command current Alu for controlling the LU command pressure Plu for engaging / slipping / releasing the lock-up clutch 20 is output to the lock-up 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 actual primary rotational speed Npri from the primary rotational sensor 90 is performed by the pulley hydraulic pressure feedback control that matches the target primary rotational speed Npri ^* . The gear ratio is represented by the slope of the gear ratio line drawn from the zero operating point, as is clear from the lowest gear ratio line and the highest gear ratio line of the D range continuously variable transmission schedule. Therefore, determining the target primary rotational speed Npri ^* by the operating point (VSP, APO) determines the target speed ratio of the variator 4.

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. The continuously variable transmission during coast deceleration by the accelerator release operation is performed by changing the vehicle speed VSP along the coast shift line (APO = 0) indicated by the thick solid line of the D range continuously variable transmission schedule.

[Configuration of lock-up control device]
FIG. 3 shows the lockup control device of the first embodiment. Hereinafter, a schematic configuration of the lockup control device will be described with reference to FIG. Lock-up 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. In addition to the continuously variable transmission control unit 8a, the CVT control unit 8 is a lockup that performs integrated lockup control to change the clutch state of the lockup clutch 20 to the engaged state / slip engaged state / released state according to various requests. A control unit 80 is provided. The lockup control unit 80 includes a coast slip control unit 80a that performs coast slip control during a coast deceleration scene by an accelerator release operation.

The integrated lockup control in the lockup control unit 80 estimates the target driving force Fd ^* intended by the driver, and locks up so that the actual driving force Fd output to the driving wheels 6 becomes the target driving force Fd ^*. It is characterized in that the slip engagement state control of the clutch 20 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 engagement state 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 is realized in the slip engagement state control of the lockup clutch 20. I am doing so.

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. The driving force demand block 81 outputs a fastening request flag and a release request flag.

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. By request arbitration, the request arbitration block 82 outputs an immediate release request flag, a release request flag, a slip request flag, an engagement request flag, and the like.

The target calculation block 83 inputs the immediate release request flag, the release request flag, the slip request flag, the engagement request flag, etc. from the request arbitration block 82, and calculates the target differential rotation speed ΔN ^* as a differential rotation target from these LU requests. To do. When the target differential rotation target or the release differential rotation target is calculated in the target calculation block 83, the target engine speed Ne ^* calculated by the driving force demand block 81 is input. For the immediate release differential rotation target and the slip differential rotation target, a preset target slip rotation speed characteristic or a target slip rotation speed characteristic set by calculation is used. Here, among the target slip rotation speed characteristics set by calculation, the target slip rotation speed characteristics set in response to the coast slip request are referred to as “target coast slip rotation speed characteristics”.

The torque capacity calculation block 84 inputs the target differential rotation speed ΔN ^* , the turbine rotation speed Nt, the actual engine rotation speed Ne, and the like 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). Here, when there is a coast slip request, the target differential rotation speed ΔN ^* based on the target coast slip rotation speed characteristic set in the target calculation block 83 is input.

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

Here, as shown in FIG. 4, the coast slip control includes each function of the coast capacity learning control that has been arranged in the realization block 85 until the request arbitration block 82, the target calculation block 83, and the torque capacity calculation block 84. Is rearranged. That is, the coast slip request function is arranged in the request arbitration block 82. In the target calculation block 83, a setting function for setting the target differential rotation speed ΔN ^* (= Ne−Nt: negative value) based on the target coast slip rotation speed characteristic in the coast slip control is arranged. The torque capacity calculation block 84 is provided with a torque capacity control function of the lockup clutch 20 based on the target differential rotation speed ΔN ^* in the coast slip control. However, when there is a coast slip request, the torque capacity calculation block 84 resets the previous converter torque F / B compensation calculated value Tcnv_fb (c) to the initial value.

[Detailed configuration of torque capacity calculation block, etc.]
FIG. 5 shows a target calculation block 83, a torque capacity calculation block 84, and a realization block 85 that constitute the coast slip control unit 80a included in 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 has a look-ahead deceleration calculator 83a and a target coast slip rotational speed characteristic setting unit 83b.

The prefetch deceleration calculator 83a receives the target gear ratio of the variator 4 from the continuously variable transmission control unit 8a, and calculates a prefetch deceleration that cancels out the hydraulic response delay in feedback compensation. In other words, the vehicle speed reduction due to the target gear ratio is prefetched using the future value (target gear ratio) that is reached after the target gear ratio is instructed, instead of the current value due to the actual gear ratio of the variator 4. .

The target coast slip rotational speed characteristic setting unit 83b includes a pre-read deceleration from the pre-read deceleration calculator 83a, a vehicle speed VSP from the vehicle speed sensor 91, a preset first target coast slip rotational speed ΔN1 ^*, and a third value. Enter the target coast slip speed ΔN3 ^* . Then, the target coast slip rotational speed characteristic based on the first target coast slip rotational speed ΔN1 ^* , the second target coast slip rotational speed ΔN2 ^* calculated based on the look-ahead deceleration, and the third target coast slip rotational speed ΔN3 ^*. Set. The first target coast slip rotational speed ΔN1 ^* is output as the target differential rotational speed ΔN ^* until the vehicle speed VSP decreases to the first set vehicle speed VSP1 after the coast slip control is started. Until the vehicle speed VSP decreases from the first set vehicle speed VSP1 to the second set vehicle speed VSP2, the second target coast slip rotational speed ΔN2 ^* is output as the target differential rotational speed ΔN ^* . When the vehicle speed VSP falls below the second set vehicle speed VSP2, the third target coast slip rotational speed ΔN3 ^* is output as the target differential rotational speed ΔN ^* .

The torque capacity calculation block 84 includes a pre-read engine torque calculator 84a, a first adder 84b, a pump load torque calculator 84c, and a first 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 first 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, in the converter torque calculation area 842, an F / F compensator 84e, a second difference unit 84f, a third difference unit 84g, an F / B compensator 84h, and a minimum value selector 84i. And a second adder 84j.

The F / F compensator 84e receives the target differential rotational speed ΔN ^* (= target coast slip rotational speed) from the target coast slip rotational speed characteristic setting unit 83b, and converts the converter torque F / according to the target differential rotational speed ΔN ^*. F compensation amount Tcnv_ff is calculated.

The second subtractor 84 f inputs the actual engine speed Ne from the engine speed sensor 12 and the turbine speed Nt from the turbine speed sensor 96. Then, the actual differential speed ΔN is calculated from the difference between the actual engine speed Ne and the turbine speed Nt.

The third differentiator 84g includes a target differential rotational speed ΔN ^* (= target coast slip rotational speed) from the target coast slip rotational speed characteristic setting unit 83b and an actual differential rotational speed ΔN (= actual slip) from the second differentiator 84f. Enter the number of revolutions). 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 third 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). The F / B compensator 84h, when there is a coast slip request due to establishment of the coast slip control start condition in the request arbitration block 82, sets the converter torque F / B compensation calculated value Tcnv_fb (c) up to the previous time as an initial value. 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 fourth differentiator 84k outside the corrected engine torque calculation area 841 and the converter torque calculation area 842. The fourth subtractor 84k calculates the target LU torque Tlu ^* by subtracting the corrected engine torque Tadj from the first 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 converter 85a converts the target LU torque Tlu ^* input from the torque capacity calculation block 84 into the LU command pressure Plu. The hydraulic pressure → current converter 85b converts the LU command pressure Plu input from the torque → hydraulic converter 85a into a command current Alu.

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

In step S100, following the start, it is determined whether or not there is a coast slip request. If YES (coast slip is requested), the process proceeds to step S101. If NO (coast slip is not requested), the process proceeds to the end.

Here, the “coast slip request” is issued when the coast slip control start condition is satisfied during traveling. The coast slip control start condition is determined to be satisfied when a predetermined time has elapsed from the start of the fuel cut control after the accelerator release operation condition is satisfied during traveling and then the fuel cut control of the engine 1 is started. The coast slip control start condition is added with an oil temperature condition that the shift hydraulic fluid temperature is equal to or higher than a predetermined temperature.

In step S101, following the determination that there is a coast slip request in step S100, the converter torque (FB) is reset, and the process proceeds to step S102.

Here, resetting the converter torque (FB) means resetting the converter torque F / B compensation calculated value Tcnv_fb (c) calculated so far by the torque capacity control process to the initial value.

In step S102, following the reset of the converter torque (FB) in step S101 or the determination that the coast slip control termination condition is not satisfied in step S109, it is determined whether or not the vehicle speed VSP is less than the first set vehicle speed VSP1. Judging. If YES (VSP <VSP1), the process proceeds to step 104. If NO (VSP ≧ VSP1), the process proceeds to step S103.

Here, the “first set vehicle speed VSP1” is a switching vehicle speed at which the coast slip control is shifted to the LU release control, and the vehicle speed value (for example, the lower limit vehicle speed range in which the coast slip control can be maintained while preventing the engine stall) (for example, 20km / h).

In step S103, following the determination that VSP ≧ VSP1 in step S102, the first target coast slip rotational speed ΔN1 ^* with a fixed value is given as the target coast slip rotational speed, and the process proceeds to step S108.

Here, the “first target coast slip rotational speed ΔN1 ^* ” is given as a coast slip differential rotational speed value (for example, about −20 rpm) in the minimum rotational speed range that can be controlled by feedback compensation (= feedback control) (see FIG. 8). ).

In step S104, following the determination that VSP <VSP1 in step S102, it is determined whether or not the vehicle speed VSP is less than the second set vehicle speed VSP2. If YES (VSP <VSP2), the process proceeds to step 107. If NO (VSP ≧ VSP2), the process proceeds to step S105.

Here, the “second set vehicle speed VSP2” is a vehicle speed that is scheduled to be released from the lockup clutch 20, and is lower than the first set vehicle speed VSP1, and is a vehicle speed value just before deceleration stop (for example, about 10 km / h). ).

In step S105, following the determination that VSP ≧ VSP2 in step S104, a pre-reading deceleration is calculated based on the target gear ratio instructed to the variator 4, and the process proceeds to step S106.

In step S106, following the calculation of the pre-reading deceleration in step S105, a second target coast slip rotational speed ΔN2 ^* in which the differential rotational speed increases with a gradient in accordance with the pre-reading deceleration of the vehicle is given, and the process proceeds to step S108.

Here, the “second target coast slip rotational speed ΔN2 ^* ” has a large vehicle look-ahead deceleration in a decreasing gradient characteristic connecting the first target coast slip rotational speed ΔN1 ^* and the third target coast slip rotational speed ΔN3 ^*. The lower the gradient angle is, the larger the angle is (see FIG. 8).

In step S107, following the determination in step S104 that VSP <VSP2, a third target coast slip rotational speed ΔN3 ^* with a fixed value is given as the target coast slip rotational speed, and the process proceeds to step S108.

Here, the “third target coast slip rotational speed ΔN3 ^* ” is given by a clutch release differential rotational speed minimum value (for example, about −2000 rpm) at which the lockup clutch 20 can be completely released (see FIG. 8). .

In step S108, following the application of the target coast slip rotational speed in step S103, step S106, or step S107, torque capacity control of the lockup clutch 20 shown in FIG. 7 is executed, and the process proceeds to step S109.

In step S109, following the LU clutch torque capacity control in step S108, it is determined whether a coast slip control end condition is satisfied. If YES (coast slip control end condition is satisfied), the process proceeds to the end. If NO (coast slip control end condition is not satisfied), the process returns to step S102.

Here, the “coast slip control end condition” refers to a condition for escaping from the coast running state (= inertia running state) by the accelerator release operation. That is, an accelerator re-depressing operation, a brake depressing operation, a vehicle stop determination, and the like are performed, and the exit condition is satisfied when the vehicle is out of the coasting state.

[Lock-up clutch torque capacity control processing configuration]
FIG. 7 shows the flow of the lock-up clutch torque capacity control process executed by the coast slip controller 80a of the CVT control unit 8 of the first embodiment. Hereinafter, each step of FIG. 7 will be described. This process is repeatedly performed in a predetermined control cycle.

In step S1, following the start, the target differential rotation speed ΔN ^* is read, and the process proceeds to step S2.

Here, the “target differential rotation speed ΔN ^* ” is the first target coast slip rotation speed ΔN1 ^* , the second target coast slip rotation speed ΔN2 ^* , or the first target slip rotation speed given in the coast slip control process of FIG. This is the 3 target coast slip rotational speed ΔN3 ^* .

In step S2, following the reading of the target differential rotation speed ΔN ^* 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 first 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 read target differential speed .DELTA.N ^* at step S1, the converter torque F / F compensation min corresponding to the target rotational speed difference ΔN ^* Tcnv_ff And proceeds to step S5.

Here, the “converter torque F / F compensation Tcnv_ff” is a lock that converges to the target differential rotational speed ΔN ^* in the F / F compensator 84e that inputs the target differential rotational speed ΔN ^* (= target coast slip rotational speed). Calculated as F / F compensation for up-torque.

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 calculated by the difference between the target differential rotational speed ΔN ^* and the actual differential rotational speed ΔN (= Ne−Nt) in the coast slip control. When there is a coast slip request, the converter torque F / B compensation calculated value Tcnv_fb (c) is reset to the initial value in the F / B compensator 84h. Then, the calculation is started as the converter torque F / B compensation for making the actual differential rotational speed ΔN coincide with the target differential rotational speed ΔN ^* .

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 converter torque Tcnv calculated in step S9 from the corrected engine torque Tadj calculated in step S3 in the fourth subtractor 84k.

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

In step S12, following the conversion to the LU command pressure Plu in step S11, the LU command pressure Plu is converted to the command current Alu in the hydraulic pressure → current converter 85b, 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 first embodiment will be described by dividing it into “coast slip control processing operation of the first embodiment” and “coast slip control operation in a coast deceleration scene with different vehicle deceleration”.

[Coast Slip Control Processing Action of Example 1]
The operation of the coast slip control process will be described based on the flowchart shown in FIG. If it is determined in S100 that there is a coast slip request, the process proceeds from S100 to S101. In S101, the converter torque F / B compensation calculated value Tcnv_fb (c) calculated up to the previous time by the torque capacity control process is the initial value. Reset to. That is, the converter torque F / B compensation calculated value Tcnv_fb (c) including the integral term is reset and the coast slip control is started.

When the coast slip control is started, the process proceeds from S101 to S102 → S103 → S108 → S109. Then, while the vehicle speed VSP is equal to or higher than the first set vehicle speed VSP1 and the coast slip control end condition is not satisfied, the flow from S102 → S103 → S108 → S109 is repeated. That is, in step S103, the first target coast slip rotational speed ΔN1 ^* based on the coast slip differential rotational speed value in the minimum rotational speed range that can be controlled by feedback control is given as the target coast slip rotational speed. In step S108, torque capacity control of the lockup clutch 20 shown in FIG. 7 is executed.

In the torque capacity control of the lockup clutch 20, the first target coast slip rotational speed ΔN1 ^* is read as the target differential rotational speed ΔN ^* in S1 of FIG. 7, and the torque capacity control process proceeds to S2 to S13 of FIG. Is executed. In the torque capacity control process, in S5, the converter torque F / B compensation calculated value Tcnv_fb (c) is calculated based on the differential rotational speed deviation δ between the target differential rotational speed ΔN ^* and the actual differential rotational speed ΔN. In S9, the converter torque Tcnv is calculated by adding the converter torque F / F compensation Tcnv_ff and the converter torque F / B compensation Tcnv_fb. In the next S10, the target LU torque Tlu ^* is calculated by subtracting the converter torque Tcnv from the corrected engine torque Tadj. In S11 to S13, the target LU torque Tlu ^* is converted into the LU command pressure Plu, the LU command pressure Plu is converted into the command current Alu, and the command current Alu is output to the lockup pressure solenoid valve 76.

When the vehicle speed VSP becomes lower than the first set vehicle speed VSP1 due to deceleration after the start of the coast slip control, the process proceeds from S102 to S104 → S105 → S106 → S108 → S109. Then, while the vehicle speed VSP is equal to or higher than the second set vehicle speed VSP2 and the coast slip control end condition is not satisfied, the flow from S102 → S104 → S105 → S106 → S108 → S109 is repeated. That is, in step S105, the look-ahead deceleration is calculated based on the target gear ratio instructed to the variator 4. In step S106, the second target coast slip rotational speed ΔN2 ^{* in} which the differential rotational speed increases with a gradient that matches the look-ahead deceleration of the vehicle is given as the target coast slip rotational speed. In step S108, torque capacity control of the lockup clutch 20 shown in FIG. 7 is executed.

In the torque capacity control of the lockup clutch 20, the second target coast slip rotational speed ΔN2 ^* is read as the target differential rotational speed ΔN ^* in S1 of FIG. 7, and the process proceeds to S2 to S13 of FIG. A torque capacity control process is executed.

When the vehicle speed VSP becomes lower than the second set vehicle speed VSP2 due to further deceleration, the process proceeds from S102 to S104 → S107 → S108 → S109. While the coast slip control end condition is not satisfied, the flow of going from S102 → S104 → S107 → S108 → S109 is repeated. That is, in step S107, the third target coast slip rotational speed ΔN3 ^* based on the clutch release differential rotational speed minimum value capable of completely releasing the lockup clutch 20 is given as the target coast slip rotational speed. In step S108, torque capacity control of the lockup clutch 20 shown in FIG. 7 is executed.

In the torque capacity control of the lockup clutch 20, the third target coast slip rotational speed ΔN3 ^* is read as the target differential rotational speed ΔN ^* in S1 of FIG. 7, and the process proceeds to S2 to S13 of FIG. A torque capacity control process is executed.

[Coast slip control action in coastal deceleration scenes with different vehicle deceleration]
First, when releasing the lock-up clutch in the coast slip control, the coast slip control is performed by the feed forward control according to the target coast slip rotational speed characteristic set according to the vehicle deceleration at the start of the control and the comparative example. To do.

In the case of this comparative example, it is feedforward control in which a control command is determined by the target coast slip rotational speed characteristic. For this reason, even if a deviation occurs between the target coast slip speed characteristic and the actual coast slip speed characteristic after the coast slip control is started, the generated deviation is allowed without being reflected in the control. Become. Therefore, there is a possibility that the release timing of the lockup clutch is deviated from a desired timing.

Therefore, there is a plan to execute coast slip control by feedback control. However, in feedback control in which a control command is determined based on a deviation between the target coast slip rotational speed and the actual coast slip rotational speed, information on the actual coast slip rotational speed with a hydraulic response delay is used. Therefore, a new cause of the shift timing of the lockup clutch being deviated from the desired timing is created due to the hydraulic response delay of the actual coast slip rotation speed information.

The present inventors pay attention to the above-mentioned problem and feedback-control the lockup differential pressure so that the actual coast slip rotational speed converges to the target coast slip rotational speed during coast deceleration by the accelerator release operation. And the structure which calculates the target coast slip rotation speed used by feedback control based on the look-ahead deceleration of a vehicle was employ | adopted.

Thus, by using the coast slip control as the feedback control, the deviation between the target coast slip rotational speed and the actual coast slip rotational speed that occurs during the coast slip control is controlled as needed. As a result, it is possible to suppress the lockup release timing from deviating from a desired timing.

Furthermore, by calculating the target coast slip rotational speed using the pre-read deceleration of the vehicle, even if the actual coast slip rotational speed information with a hydraulic response delay is used, the target coast slip rotation in which the hydraulic response delay becomes the pre-read information. Offset by number. As a result, response delay due to feedback control can be suppressed during coast slip deceleration.

FIG. 8 is a time chart showing each characteristic in a coast deceleration scene where the vehicle deceleration is different. Hereinafter, the coast slip control action in a coast deceleration scene with different vehicle deceleration will be described with reference to FIG.

Assuming that the vehicle speed characteristics of the large vehicle deceleration (0.5G) are A, the section from time t0 to time t1 when the vehicle speed VSP reaches the first set vehicle speed VSP1 in the lower limit vehicle speed range where coast slip control can be maintained is the first target. The coast slip control section maintains the coast slip rotational speed ΔN1 ^* . The section from time t1 to time t2 when the second set vehicle speed VSP2 is reached is the LU clutch release control section based on the second target coast slip rotational speed ΔN2 ^* . Furthermore, the section after time t2 is the LU clutch complete release section that maintains the third target coast slip rotational speed ΔN3 ^* .

Assuming that the vehicle speed characteristics during vehicle deceleration (0.2G) is B, the section from time t0 to time t1 when the vehicle speed VSP reaches the first set vehicle speed VSP1 in the lower limit vehicle speed range where coast slip control can be maintained is the first target. The coast slip control section maintains the coast slip rotational speed ΔN1 ^* . The section from the time t1 to the time t3 when the second set vehicle speed VSP2 is reached is the LU clutch release control section based on the second target coast slip rotational speed ΔN2 ^* . Further, the section after time t3 is the LU clutch complete release section in which the third target coast slip rotational speed ΔN3 ^* is maintained.

If the vehicle speed characteristic of small vehicle deceleration (0.1G) is C, the first target is the section from time t0 to time t1 when the vehicle speed VSP reaches the first set vehicle speed VSP1 in the lower limit vehicle speed range where coast slip control can be maintained. The coast slip control section maintains the coast slip rotational speed ΔN1 ^* . The section from time t1 to time t4 when reaching the second set vehicle speed VSP2 is the LU clutch release control section based on the second target coast slip rotational speed ΔN2 ^* . Further, the section after time t4 is the LU clutch complete release section in which the third target coast slip rotational speed ΔN3 ^* is maintained.

Therefore, the vehicle speed characteristics A, B, and C are compared. In the case of the vehicle speed characteristic A with a large vehicle deceleration (0.5 G ⁾ , the decreasing gradient angle due to the second target coast slip rotational speed ΔN2 ^{* in} the LU clutch release control section is the largest angle. In the case of the vehicle speed characteristic A, the LU clutch release control time TA (= t1 to t2) is the shortest time, and the time t2 is the release timing of the lockup clutch 20.

In the case of the vehicle speed characteristic B during vehicle deceleration (0.2G), the decreasing gradient angle due to the second target coast slip rotational speed ΔN2 ^{* in} the LU clutch release control section is an intermediate angle between the vehicle speed characteristic A and the vehicle speed characteristic C. In the case of the vehicle speed characteristic B, the LU clutch release control time TB (= t1 to t3) is an intermediate time between the vehicle speed characteristic A and the vehicle speed characteristic C, and the time t3 is the release timing of the lockup clutch 20.

In the case of the vehicle speed characteristic C with a small vehicle deceleration (0.1 G), the decrease gradient angle due to the second target coast slip rotational speed ΔN2 ^{* in} the LU clutch release control section is the smallest angle. In the case of the vehicle speed characteristic C, the LU clutch release control time TC (= t1 to t4) is the longest time, and the time t4 is the release timing of the lockup clutch 20.

Thus, if the vehicle deceleration due to the vehicle speed characteristics A, B, and C is accurately grasped, an appropriate release timing of the lockup clutch 20 can be obtained regardless of the magnitude of the vehicle deceleration.

As described above, in the lock-up control device for the belt-type continuously variable transmission CVT according to the first embodiment, the following effects can be obtained.

(1) The torque converter 2, the lockup clutch 20, and the lockup 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 lockup controller (CVT control unit 8) controls the engagement / slip / release of the lockup clutch 20.
The lockup controller (CVT control unit 8) is provided with a coast slip control unit 80a that feedback-controls the lockup differential pressure so that the actual slip rotation speed converges to the target coast slip rotation speed during coast deceleration by the accelerator release operation. .
The coast slip control unit 80a calculates the target coast slip rotational speed used in the feedback control based on the look-ahead deceleration of the vehicle (FIG. 3).
Thus, the target coast slip rotational speed used in the feedback control is calculated using the look-ahead deceleration of the vehicle. As a result, at the time of coast slip deceleration, it is possible to suppress the lockup release timing from deviating from a desired timing while suppressing response delay due to feedback control.

(2) The transmission mechanism is a continuously variable transmission mechanism (variator 4).
The coast slip control unit 80a calculates the pre-reading deceleration of the vehicle based on the target gear ratio instructed to the continuously variable transmission mechanism (variator 4) (FIG. 5).
In this way, the look-ahead deceleration of the vehicle is calculated based on the target gear ratio acquired from the continuously variable transmission control unit 8a. As a result, it is possible to accurately calculate the look-ahead deceleration of the vehicle that cancels out the hydraulic response delay.
That is, the target speed ratio acquired from the continuously variable speed control unit 8a is a speed change instruction value, and becomes the actual speed ratio after a time corresponding to the hydraulic response delay has elapsed since the target speed ratio was instructed. That is, the target gear ratio can be said to be gear ratio information obtained by prefetching the hydraulic response delay.

(3) When there is a coast slip request, the coast slip control unit 80a performs the third target coast slip rotation from the first target coast slip rotation speed ΔN1 ^* through the second target coast slip rotation speed ΔN2 ^* according to the deceleration of the vehicle. Sets the target coast slip speed characteristic that shifts to the number ΔN3 ^* .
The first target coast slip rotational speed ΔN1 ^* is given as a coast slip differential rotational speed value in the minimum rotational speed range that can be controlled by feedback control.
The second target coast slip rotational speed ΔN2 ^* is given as a differential rotational speed calculated value that increases the differential rotational speed with a gradient that matches the pre-read deceleration of the vehicle.
The third target coast slip rotational speed ΔN3 ^* is given as a clutch release differential rotational speed value at which the lockup clutch 20 can be completely released (FIG. 8).
Thus, the target coasting slip rotation speed characteristic, and set the properties from the first target coasting slip revolution speed .DELTA.N1 ^* via a second target coasting slip revolution speed .DELTA.N2 ^* transitions third target coasting slip revolution speed .DELTA.N3 ^* ing. The second target coast slip rotational speed ΔN2 ^* increases with a gradient that matches the look-ahead deceleration of the vehicle. As a result, when shifting from the coast slip control state to the lockup release state, it is possible to suppress a change in vehicle behavior due to the lockup release and to completely release the lockup clutch 20 smoothly.

(4) The coast slip control unit 80a sets the target coast slip rotational speed characteristics to the first set vehicle speed VSP1 in the lower limit vehicle speed range in which coast slip control can be maintained, and to the second setting on the lower vehicle speed side than the first set vehicle speed VSP1. The target coast slip rotational speed is shifted according to the vehicle speed VSP2.
The selected section of the first target coast slip rotational speed ΔN1 ^* is a deceleration section from the start vehicle speed of coast slip control to the first set vehicle speed VSP1.
The selected section of the second target coast slip rotational speed ΔN2 ^* is a deceleration section from reaching the first set vehicle speed VSP1 to reaching the second set vehicle speed VSP2.
The selected section of the third target coast slip rotational speed ΔN3 ^* is set as the deceleration section after reaching the second set vehicle speed VSP2 (FIG. 8).
As described above, the first set vehicle speed VSP1 is set to the vehicle speed in the lower limit vehicle speed range in which the coast slip control can be maintained. The period from the start of the coast slip control to the arrival at the first set vehicle speed VSP1 is set as the selection section of the first target coast slip rotational speed ΔN1 ^* . As a result, at the time of coast deceleration, a section in which coast slip control with a minute slip amount is executed can be secured long until the vehicle speed limit is approached.

(5) The lockup 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. The lockup control unit 80 executes slip control for obtaining a target LU torque Tlu ^* calculated by subtracting the converter torque Tcnv from the input torque (corrected engine torque Tadj) to the torque converter 2.
When there is a coast slip request, the coast slip control unit 80a resets the feedback compensation amount of the converter torque Tcnv to an initial value and starts coast slip control (FIG. 6).
As described above, when coast slip control is started, the feedback compensation amount of the converter torque Tcnv is reset to the initial value. As a result, when coast slip control is executed using the lockup control unit 80, stable slip rotation can be maintained immediately after the start of coast slip control.
In other words, the lock-up control unit 80 is not a dedicated control unit for coast slip control, but is also used for other controls such as smooth LU control. For this reason, at the start of the coast slip control, by resetting the initial value for the feedback compensation of the converter torque Tcnv, the influence on the coast slip control due to the torque value for the feedback compensation by the integral term until the previous time is eliminated. .

The automatic transmission lockup control device of the present invention has been described based on the first embodiment. 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 first embodiment, the lockup control unit 80 has the driving force demand block 81 that converts the target driving force Fd ^* into the target engine speed Ne ^* . However, the lockup control unit may be an example that does not have a driving force demand block and performs coast slip control by giving a target coast slip rotational speed characteristic.

Example 1 shows 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. 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

A torque converter interposed between the traveling drive source and the speed change mechanism;
A lock-up clutch that is connected to the torque converter input shaft and the torque converter output shaft by fastening;
A lockup controller for controlling the engagement / slip / release of the lockup clutch, and
In the lockup controller, a coast slip control unit that feedback-controls the lockup differential pressure is provided so that the actual slip rotation speed converges to the target coast slip rotation speed during coast deceleration by an accelerator release operation,
The coast slip control unit calculates the target coast slip rotational speed used in feedback control based on a look-ahead deceleration of a vehicle.
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to claim 1,
The transmission mechanism is a continuously variable transmission mechanism,
The coast slip control unit calculates a look-ahead deceleration of the vehicle based on a target gear ratio instructed to the continuously variable transmission mechanism;
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to claim 1 or 2,
When there is a coast slip request, the coast slip control unit shifts from the first target coast slip rotational speed to the third target coast slip rotational speed via the second target coast slip rotational speed as the vehicle decelerates. Set the slip speed characteristics,
The first target coast slip rotational speed is given as a coast slip differential rotational numerical value in a minimum rotational speed range that can be controlled by feedback control,
The second target coast slip rotational speed is given as a differential rotational speed calculated value in which the differential rotational speed increases with a gradient that matches the look-ahead deceleration of the vehicle,
The third target coast slip rotation speed is given as a clutch release differential rotation value capable of completely releasing the lockup clutch.
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to claim 3,
The coast slip control unit determines the target coast slip rotational speed characteristic by a first set vehicle speed in a lower limit vehicle speed range in which coast slip control can be maintained and a second set vehicle speed on the vehicle speed side lower than the first set vehicle speed. Each target coast slip rotation speed has a characteristic to shift,
The selected section of the first target coast slip rotational speed is a deceleration section from the start vehicle speed of coast slip control until reaching the first set vehicle speed,
The selected section of the second target coast slip rotational speed is a deceleration section from reaching the first set vehicle speed to reaching the second set vehicle speed,
The third target coast slip rotational speed selection section is a deceleration section after reaching the second set vehicle speed,
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to any one of claims 1 to 4,
The lockup controller calculates a converter torque by feedforward compensation based on a target differential rotational speed and feedback compensation based on a differential rotational speed deviation, and calculates a target lockup calculated by subtracting the converter torque from an input torque to the torque converter. A lock-up control unit that executes slip control for obtaining torque;
When there is a coast slip request, the coast slip control unit resets the feedback compensation amount of the converter torque to an initial value, and starts coast slip control.
Automatic transmission lockup control device.