JP3411075B2 - Fluid coupling fastening force control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening force control device for a fluid coupling having a lockup clutch.

[0002]

2. Description of the Related Art Generally, in an automobile equipped with an automatic transmission, a torque converter, which is a kind of fluid coupling, is provided in a power transmission path between an engine and a mechanical transmission gear mechanism. Then, the torque converter is integrated with the pump (driving-side rotating member) that rotates integrally with the engine output shaft to discharge hydraulic oil, and the turbine shaft (input shaft of the speed change gear mechanism) that is driven by the hydraulic oil discharged from the pump. It has a rotating turbine (driven side rotating member) and a stator that rectifies the flow of hydraulic oil between the pump and turbine, and the torque of the engine output shaft (engine output torque).
Is transmitted to the speed change gear mechanism with a speed change ratio determined by a rotational speed difference (that is, a rotational speed difference) between the pump and the turbine.

However, in such a torque converter, there is a problem that a relatively large power loss occurs due to the viscous resistance of the working oil because the torque is transmitted from the driving side to the driven side via the working oil. Therefore, the torque converter is usually provided with a lock-up clutch that directly connects (locks up) the engine output shaft (pump) and the turbine shaft (turbine) in a predetermined operating region. The lock-up clutch is engaged (locked up) in an operating region where the torque increasing action of the torque converter is not so required, that is, in a low output region.At the time of lockup, the torque of the engine output shaft does not directly pass through the hydraulic oil. It is transmitted to the speed change gear mechanism side so that power loss is reduced.

However, when the lockup clutch is engaged and the engine output shaft and the turbine shaft are directly connected, torque fluctuation or rotation speed fluctuation of the engine output shaft is caused.
At low rotation speeds (i.e., fluctuations in rotational speed), such torque fluctuations or rotational speed fluctuations are directly transmitted to the speed change gear mechanism, so that vibration or rattling occurs in the speed change gear mechanism. For this reason, the ordinary lock-up clutch has a problem that the lock-up region cannot be expanded to such a low rotation region and fuel efficiency cannot be sufficiently improved.

Therefore, the difference between the hydraulic pressure applied to the front end surface and the hydraulic pressure applied to the rear end surface of the lock-up clutch.
(Structure that allows the pump and the turbine to be fastened together with a fastening force according to the (fluid differential pressure), and controls the fastening force in a predetermined operating range to provide an appropriate slip (slip) to the lockup clutch. A torque converter is provided that causes the pump and the turbine to rotate appropriately to make a differential rotation, and that the slipping or the differential rotation absorbs torque fluctuations or rotation speed fluctuations of the engine output shaft to perform fastening force control, so-called slip control. It has been proposed (see, for example, Japanese Patent Publication No. 63-13060).

In such a conventional torque converter, the rotational speed difference (rotational speed difference) between the pump and the turbine normally follows a predetermined target rotational speed difference (target rotational speed difference) during engagement force control. Thus, the engagement force (fluid differential pressure) of the lockup clutch is feedback-controlled. And by performing such fastening force control,
Lockup (slip state) can be performed without problems even in the low rotation range where lockup was difficult in the past.
It has become possible to improve fuel efficiency.

[0007]

However, in the conventional torque converter in which the engagement force control is performed by feedback-controlling the engagement force of the lockup clutch in the predetermined operation region as described above, the lockup clutch is If the engagement force control is started from the state where the torque converter is not normally engaged (converter mode) or the lockup clutch is completely locked up (lockup mode), the engagement force control is performed. When it is started, there is a problem that the difference in rotational speed between the pump and the turbine does not easily converge to the target rotational speed difference, and the responsiveness or control accuracy of the fastening force control deteriorates.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is for rotating the drive side with respect to a torque converter having a lockup clutch and other fluid couplings at the start of fastening force control. An object of the present invention is to provide a means capable of quickly converging a difference in rotational speed between a member and a driven-side rotating member to a target rotational speed difference, and improving responsiveness and control accuracy of fastening force control. To do.

[0009]

To reach the above object, according to the solution to ## to indicate the configuration in FIG. 1, according to the first aspect of the present invention
The fastening force control device for a fluid coupling includes a driving side rotating member b that is rotationally driven by a driving source a, and a driven side rotating member c that is rotationally driven by the driving side rotating member b via fluid.
Drive side rotating member b with fastening force according to the applied fluid pressure difference
In the fastening force control device f of the fluid coupling e provided with the lock-up clutch d capable of engaging the driven side rotating member c and the driven side rotating member c, the input torque for detecting the torque input to the driving side rotating member b. Detection means g, drive side rotation speed detection means h for detecting the rotation speed of the drive side rotation member b, driven side rotation speed detection means i for detecting the rotation speed of the driven side rotation member c, and drive side rotation Rotational speed of member b and driven side rotating member
When the difference in the number of revolutions of c exceeds a predetermined value, the fluid pressure difference applied to the lockup clutch d is determined by the input torque detected by the input torque detecting means g and the driven side detected by the driven side rotational speed detecting means i. When the difference between the fluid differential pressure control means j that controls based on the target differential pressure set according to the rotation speed of the side rotation member c and the rotation speed is equal to or less than the predetermined value, the difference in the rotation speed is predetermined. Feedback control means for feedback controlling the fluid pressure difference applied to the lockup clutch d so as to follow the target rotational speed difference of
It shall be the feature of the k and are provided.

The fluid differential pressure control means j of the fastening force control device f for the fluid coupling e according to the first aspect of the present invention reduces the rate of change of the control amount of the fluid differential pressure as the fluid differential pressure approaches the target differential pressure. that has become to be set.

Control of fastening force of a fluid coupling according to the second invention
The device is the fastening force control device f for the fluid coupling e according to the first aspect of the invention, wherein the feedback control means k sets the target differential pressure and the lockup clutch at the time of shifting to feedback control.
The difference between the differential fluid pressure exerted on the d, characterized in that it is adapted to reflect a feedback control.

Control of fastening force of a fluid coupling according to a third aspect of the invention
In the device , in the fastening force control device f for the fluid coupling e according to the second aspect of the invention, the fluid differential pressure control means j starts the fastening force control of the lockup clutch d based on the change characteristic of the control amount of the fluid differential pressure. change in the time to stop the time, and you characterized in that it is adapted to change in accordance with the presence or absence of presence and speed of change of the engine load.

Control of fastening force of a fluid coupling according to a fourth aspect of the invention
The device is the fastening force control device f for the fluid coupling e according to the third aspect of the invention, wherein the fluid pressure difference control means j and the feedback control means k are applied to the lockup clutch d according to the change of the source pressure of the fluid. as pressure is not changed, it characterized in that it is adapted to correct the control amount of the differential fluid pressure in accordance with the original pressure of the fluid.

[0014]

EXAMPLES Examples of the present invention will be specifically described below.
As shown in FIG. 2, the power train PT for automobiles is
Basically, the output torque of the engine 1 is changed by the torque converter 2, and further is changed by the multi-stage speed change gear mechanism 3 including planetary gears and is output to the transmission output shaft 4. The engine 1 and the torque converter 2 respectively correspond to the "driving source" and the "fluid coupling" described in the claims.

The engine 1 is an ordinary four-cylinder engine that uses gasoline as fuel, and converts thermal energy generated by burning fuel into mechanical energy and shifts this in the form of rotational force (torque). It is designed to output to the machine side. The engine 1 is provided with an intake device 5 that supplies air for fuel combustion to each cylinder.
The intake device 5 is provided with a common intake passage 6 whose tip is open to the atmosphere. The common intake passage 6 removes dust in the intake air sequentially from the upstream side in the flow direction of the intake air. An air cleaner 7, an air flow sensor 8 that detects an intake air amount, and a throttle valve 9 that opens and closes in accordance with the depression amount of an accelerator pedal (not shown) are provided. The common intake passage 6 branches into four branch intake passages 10 downstream of the throttle valve 9, and each of these branch intake passages 10 is supplied to a combustion chamber (not shown) of a corresponding cylinder to burn air for fuel combustion. Are to be supplied.

A control unit C equipped with a microcomputer is provided for various controls of the power train PT. The control unit C has an intake air amount detected by an air flow sensor 8 and a throttle opening sensor 11. The throttle opening detected, the turbine speed (rotation speed) detected by the turbine speed sensor 12, the engine speed (rotation speed) detected by the engine speed sensor 13, and the oil detected by the oil temperature sensor 14. The temperature (temperature of hydraulic oil), the line pressure (source pressure) detected by the hydraulic pressure sensor 15, the battery voltage detected by the voltage sensor 16, and the like are input as control information. Since the line pressure (original pressure) is formed corresponding to the output signal of the control unit C, the line pressure forming signal in the control unit C may be used without providing the hydraulic pressure sensor. .

As will be described later, the control unit C performs a predetermined control on the torque converter 2 via the first and second solenoid valves 17 and 18, and a plurality of control units on the transmission gear mechanism 3. Various solenoid valves 1
The shift control is performed via the control unit 9. here,
Although not shown in detail, the speed change gear mechanism 3 includes an ordinary planetary gear system including a sun gear, a ring gear, a pinion gear, a carrier, and various hydraulic clutches for connecting and disconnecting torque between these gears. It is a mechanical transmission equipped with various brakes and various one-way clutches, and a control unit C is capable of automatically switching gears via various solenoid valves 19 according to an operating state of a power train PT. ing. The turbine rotation speed sensor 12 and the engine rotation speed sensor 13 respectively correspond to the “driven side rotation speed detection means” and the “drive side rotation speed detection means” described in the claims. The control unit C is a comprehensive control device including the “input torque detection means”, the “fluid differential pressure control means”, and the “feedback control means” described in the claims.

As shown in FIG. 3, the torque converter 2 has a pump 23 (pump impeller) mounted in a converter case 22 connected to the engine output shaft 21 and rotating integrally with the engine output shaft 21 to discharge hydraulic oil. ) And a turbine 24 which is arranged so as to face the pump 23 and is rotationally driven by hydraulic oil discharged from the pump 23.
A (turbine runner) and a stator 25 that is arranged between the pump 23 and the turbine 24 and rectifies the flow of the hydraulic oil between the pump and the turbine are provided. The stator 25 is fixed to the transmission case 27 via a one-way clutch 26. The torque of the turbine 24 is transmitted to the speed change gear mechanism 3 (see FIG. 2) via a pipe-shaped turbine shaft 28 having a hollow portion.
Although not shown, a shaft that penetrates the hollow portion of the turbine shaft 28 is connected to the engine output shaft 21, and the oil pump is rotationally driven by this shaft. The pump 23 and the turbine 24
And correspond to the "driving side rotating member" and the "driven side rotating member" described in the claims, respectively. The hydraulic oil corresponds to the "fluid" described in the claims.

Further, the torque converter 2 has a lockup for directly connecting (including a slip state) the engine output shaft 21 (pump 23) and the turbine shaft 28 (turbine 24) depending on the operating state, as will be described later. A clutch 29 is provided. In the following, for convenience, the right side (engine side) is referred to as "front" and the left side (transmission gear mechanism side) is referred to as "rear" in the positional relationship in FIG.

The lock-up clutch 29 has a front wall portion 30 of the converter cover 22 connected to the engine output shaft 21 when viewed in the axial direction (front-back direction) of the turbine shaft.
And a turbine 24, and a torsion damper 31 and a damper piston 32 that rotate integrally with the turbine shaft 28, and friction that is attached to the rear surface of the front wall portion 30 at a position facing the damper piston 32. And a plate (not shown). Then, the damper piston 32 is provided with a space formed in the converter case 22,
It is partitioned into a rear chamber 33 located on the rear side and a front chamber 34 located on the front side. Here, the hydraulic pressure in the rear chamber 33 (pressure of hydraulic oil) becomes the operating pressure in the lock-up strengthening direction that acts in the direction (forward) of pressing the damper piston 32 against the friction plate, and the hydraulic pressure (operating pressure in the front chamber 34) The oil pressure) is an operating pressure in the lock-up releasing direction that acts in a direction (rearward direction) of separating the damper piston 32 from the friction plate.

The damper piston 32 is attached to the rear chamber 33.
The friction plate is frictionally engaged with or released from the friction plate by a fastening force corresponding to the difference between the oil pressure inside and the oil pressure inside the front chamber 34 (hereinafter, referred to as fluid pressure difference). That is, in accordance with the fluid pressure difference, the lockup clutch 29 is completely released, and the torque of the engine output shaft 21 is transmitted to the turbine shaft 28 via the hydraulic oil. Is locked completely (without slip) and the torque of the engine output shaft 21 is directly transmitted to the turbine shaft 28, and the damper piston 32 frictionally engages the friction plate while appropriately slipping. In the semi-engaged state (slip state), the torque of the engine output shaft 21 is transmitted to the turbine shaft 28 via the hydraulic oil, and
Three types of transmission modes, the slip mode, which is transmitted to the turbine shaft 28 via the lockup clutch 29, are obtained.

The torque converter 2 is provided with a hydraulic mechanism 40 for switching the transmission mode of the lockup clutch 29 and controlling the engaging force in accordance with a control signal applied from the control unit C. The hydraulic mechanism 40 includes a shift valve 41 that switches a hydraulic pressure supply path, a control valve 42 that regulates the hydraulic pressure supplied to the front chamber 34 via the shift valve 41, and a first valve.
A first solenoid valve 17 for controlling ON / OFF of the pilot pressure and a second solenoid valve for controlling the duty of the second pilot pressure.
A solenoid valve 18 is provided.

Further, the hydraulic mechanism 40 includes a torque converter line L1 into which a line pressure output from a pressure regulator valve (not shown) is introduced, a first pilot line L2 for supplying a first pilot pressure, and a second pilot line L2. A second pilot line L3 that supplies pilot pressure, a constant pressure line L4 that supplies a constant pressure to the shift valve 41, a rear line LR that connects the port 43 of the shift valve 41 and the rear chamber 33, and a port 44 of the shift valve 41. A front line LF that connects the front chamber 34 with the front chamber is provided. And the torque converter line L1 is the line L11 and the line L1.
The line L11 is connected to the port 45 of the shift valve 41, and the line L12 is connected to the port 46 of the control valve 42. The port 47 of the control valve 42 is connected to the port 48 of the shift valve 41 via the line L13. The port 49 of the shift valve 41 is connected to the line L5 whose tip is connected to the oil cooler 50.

The first pilot line L2 is the line L2
1 and the line L22, the line L21 is connected to the port 51 of the shift valve 41, and the line L22 is connected to the port 52 of the control valve 42. And the 1st solenoid valve 17 is interposed in the drain line L23 branched from the line L21. here,
When the first solenoid valve 17 is in the off state, the drain line L23 is closed, while when it is in the on state, the drain line L23 is opened (drained).

The second pilot line L3 is the line L31.
The line L31 is connected to the port 53 of the shift valve 41, and the line L32 is connected to the port 54 of the control valve 42. And the 2nd solenoid valve 18 is interposed in the drain line L33 branched from the 2nd pilot line L3. Here, when the second solenoid valve 18 is in the off state, the drain line L33 is closed, and when it is in the on state, the drain line L33 is opened (drained). Also, in the intermediate area between both (on / off),
A second pilot pressure is formed in the second pilot line L3 according to the duty ratio. The second pilot pressure decreases as the duty ratio increases.

In the shift valve 41, the ports 43 and 45 are operated by the operation of the two spools 55 and 56 which are regulated by the first and second pilot pressures, respectively.
Alternatively, switching of the communication state with the port 49 and switching of the communication state with the port 44 and the port 48 or the drain port are performed. In the control valve 42, the port 47 and the port 46 are controlled by the operation of the spool 60 regulated by the first and second pilot pressures.
Alternatively, the communication state with the drain port is switched. In the line LC, the hydraulic oil in the torque converter 2 is passed through the check valve 57 to the oil cooler 50.
It is an oil passage to lead to.

Switching of the three kinds of transmission modes (converter mode, lockup mode, slip mode) of the lockup clutch 29 is performed according to a control signal applied from the control unit C according to the operating state of the power train PT. Specifically, for example, the transmission mode corresponding to the operating state is selected based on the lockup control map having the throttle opening and the turbine rotation speed as parameters, and the control signal corresponding to the transmission mode is output from the control unit C. It is applied to the first and second solenoid valves 17 and 18, and accordingly, the shift valve 41
The control valve 42 is operated to switch the transmission mode of the lockup clutch 29. Further, in the slip mode, the engagement force control of the lock-up clutch 29 is performed as described later, and basically, the rotation speed (rotation speed) of the engine output shaft 21 and the rotation speed (rotation speed) of the turbine shaft 28 (rotation speed). (Hereinafter, this is referred to as input / output rotational speed difference), that is, the slip amount follows a predetermined target value (hereinafter, referred to as target rotational speed difference) so that the fluid pressure difference applied to the lockup clutch 29, that is, The engagement force of the lockup clutch 29 is feedback-controlled.

In the lockup control map, the acceleration demand is strong in a predetermined low rotation / medium / high load region, and therefore, the torque increasing action of the torque converter 2 is indispensable, so that good acceleration performance is obtained in the converter mode. ing. Further, in a predetermined high rotation / medium / low load region, the torque increasing action of the torque converter 2 is not required so much, and the torque fluctuation or rotation speed fluctuation on the engine side is small, so that the engine output shaft 2
Since there is no possibility of vibration or rattling of the speed change gear mechanism 3 even if 1 and the turbine shaft 28 are directly connected, the power loss is reduced and the fuel economy performance is improved by setting the lockup mode. Further, in the predetermined low rotation speed / low load region, if the engine output shaft 21 and the turbine shaft 28 are directly connected, vibrations of the transmission gear mechanism 3 are caused by torque fluctuations or rotation speed fluctuations on the engine side. As a mode, torque fluctuation or rotation speed fluctuation on the engine side is absorbed by the slip of the lockup clutch 29.

Hereinafter, the hydraulic mechanism 40 in each transmission mode will be described.
The operation of the lockup clutch 29 will be specifically described. (1) Converter Mode In the converter mode, the first solenoid valve 17 is turned off and the duty ratio of the second solenoid valve 18 is set to 0%. By this, both spools 55,
56 is arranged in the leftward position (FIG. 3 shows this state). At this time, the port 43 communicates with the port 49, and the hydraulic pressure in the rear chamber 33 is released to the oil cooler 50 via the rear line LR and the line L5. On the other hand,
Port 44 communicates with port 48, torque converter line L1
Through line L12 and ports 46 and 47 to line L
The hydraulic pressure guided to 13 is supplied to the front chamber 34 via the front line LF. Therefore, the rear chamber 33 is replaced by the front chamber 34.
The pressure becomes lower than that and the lockup clutch 29 is turned off.
(Released) and the torque is converted.

(2) Lockup mode In the lockup mode, the first solenoid valve 17 is turned on and the duty ratio of the second solenoid valve 18 is set to 0%. This allows both spools 5
5,56 are arranged on the right side. At this time, the port 43 communicates with the port 45, and the hydraulic pressure of the torque converter line L1 is transmitted through the line L11 and the rear line LR to the rear chamber 3
3 is supplied. On the other hand, the port 44 communicates with the drain port, and the hydraulic pressure in the front chamber 34 is released. Therefore, the fluid pressure difference (the pressure difference between the rear chamber 33 and the front chamber 34) reaches the maximum value substantially corresponding to the line pressure, the lockup clutch 29 is completely engaged, and no slip occurs.

(3) Slip mode In the slip mode, the first solenoid valve 17 is turned on. The duty ratio of the second solenoid valve 18 is the deviation of the input / output rotational speed difference from the target rotational speed difference.
It is set to a value corresponding to (hereinafter, referred to as rotation speed deviation). As a result, the spool 55 is arranged at the rightward position, while the spool 56 is arranged at the leftward position. At this time, the port 43 communicates with the port 45, and the hydraulic pressure in the torque converter line L1 is supplied to the rear chamber 33. On the other hand, the port 44 communicates with the port 48, and basically the hydraulic pressure in the torque converter line L1 is also supplied to the front chamber 34. However, the hydraulic pressure supplied to the front chamber 34 is controlled by the second solenoid valve 18 according to its duty ratio. Therefore, the fluid pressure difference is controlled according to the duty ratio, and the engagement force of the lockup clutch 29 is controlled accordingly.

Further, in this slip mode,
As will be described later, basically, in order to make the input / output rotational speed difference follow the target rotational speed difference, the engaging force of the lock-up clutch 29 is set so as to eliminate the rotational speed deviation according to the rotational speed deviation.
Fastening force control, that is, slip control, such as adjusting (fluid differential pressure) is performed.

The control unit C controls the transmission mode of the lock-up clutch 29 via the hydraulic mechanism 40 and controls the engagement of the lock-up clutch 29 (slip control). (Hereinafter collectively referred to as clutch control), the control unit C is referred to in accordance with the flow charts shown in FIGS. 4 to 7 while referring to FIGS.
A control method of the lockup clutch control by the will be described.

In this lock-up clutch control, in the slip mode, basically, the target rotational speed difference is set according to the operating state of the power train PT, and the input / output rotational speed difference follows the target rotational speed difference. In order to eliminate the rotational speed deviation, the fluid pressure difference (fastening force)
While performing the feedback control such as the control of the engine, when the rotational speed deviation becomes particularly large at the time of starting the engaging force control, shifting, etc., the fluid pressure difference is set to the output torque of the engine 1 (the input torque to the pump 23) and the turbine. Based on the target differential pressure set according to the rotational speed, feed-forward control is performed such that the fluid differential pressure is controlled to approach the target differential pressure, and the input / output rotational speed is quickly increased without causing overshoot. Converging the difference to the target speed difference (following)
The responsiveness and control accuracy of the fastening force control are improved.

In the lock-up clutch control routine shown in FIGS. 4 to 7, is step # 1 to step # 6 to perform the engagement force control (slip control) of the lock-up clutch 29 by grasping the operating state of the power train PT? It is a routine for determining whether or not.

Steps # 7 to # 28 are fluid differential pressures DLUP to be set when engaging force control is performed.
[i], that is, a routine for calculating the required fluid pressure difference DLUP [i]. In the following, DLUP [i] is the fluid pressure difference calculated this time, and DLUP [i-1] is the fluid pressure difference calculated last time. More details, step #
Steps 7 to step # 8 are a routine for calculating the target differential pressure PSL and determining whether or not the shift is in progress. Steps # 9 to # 20 are to make the fluid pressure difference DLUP [i] quickly approach the target pressure difference PSL, that is, to set the input / output speed difference (NE-TREV) to the target speed difference KEDN1.
Is a routine for performing feedforward control of the fluid differential pressure DLUP [i] based on the target differential pressure PSL in order to quickly follow the above. In steps # 21 to # 22, the input / output rotation speed difference (NE-TREV) is the target rotation speed difference KEDN.
This is a routine for performing feedback control such that the fluid differential pressure DLUP [i] is used as a control amount so as to follow 1. Steps # 23 to # 28 are for making the fluid differential pressure DLUP [i] quickly approach the target differential pressure PSL when the shift stage of the transmission gear mechanism 3 is switched (shifted) during the engagement force control. Then, based on the target differential pressure PSL, the fluid differential pressure DLUP [i]
Is a routine for feed-forward control.

In steps # 29 to # 36, the fluid pressure difference DLUP to be set when the control of the engagement force of the lock-up clutch 29 is stopped and the converter mode is entered.
This is a routine for calculating [i].

In steps # 37 to # 39, the deviation of the fluid pressure difference DLUP [i] from the target pressure difference PSL (hereinafter,
This is called a fluid differential pressure deviation), and a duty ratio DUTY to be applied to the second solenoid valve 18 corresponding to the set fluid differential pressure DLUP [i] is calculated, and this duty ratio DUTY is This is a routine for outputting to the 2-solenoid valve 18.

Specifically, when the control is started, first, in step # 1, the turbine speed TREV detected by the turbine speed sensor 12 and the engine speed sensor 13 are detected.
Engine speed NE detected by, engine 1 output torque TN (hereinafter referred to as engine torque TN), throttle opening THVOL detected by throttle opening sensor 11, oil temperature detected by oil temperature sensor 14. THOIL (temperature of hydraulic oil), hydraulic pressure sensor 15
The control information includes the line pressure PL (source pressure of the hydraulic mechanism 40) detected by the battery pressure, the battery voltage Vb (input voltage to the control unit C) detected by the voltage sensor 16, the intake air amount detected by the air flow sensor 8 and the like. Is read as. The output torque T of the engine 1
N is the throttle opening THVOL and engine speed NE
Although it is calculated in the control unit C based on the above, it may be calculated using the intake air amount, the engine speed, and the ignition timing. Further, a torque sensor is provided for the engine output shaft 21, It is also possible to directly detect the output torque TN of.

Subsequently, a shift determination is made in step # 2, and the gear stage gear of the transmission gear mechanism 3 and the shift flag SFT are determined.
UP and are output. Here, the gear stage gear is the gear stage most suitable for the operating state of the power train PT (throttle opening THVOL and turbine speed TREV),
It is calculated by searching a predetermined shift map using the throttle opening THVOL and the turbine speed TREV as parameters. Note that the speed change gear mechanism 3 is controlled by a control unit C through various solenoid valves 19 so that the actual shift speed thereof coincides with this shift speed gear in another shift control routine (not shown). Of course. In addition, the shift flag SFTUP
Is a flag that is set (SFTUP = 1) at the start of the shift and reset (SFTUP = 0) at the end of the shift (see FIG. 9).

Next, at step # 3, the turbine speed TR
It is determined whether the EV exceeds f (THVOL, gear). Here, f is a predetermined function that sets THVOL and gear as independent variables for setting the operating region in which the engagement force control of the lockup clutch 29 is to be performed, and
When V> f (THVOL, gear), the fastening force control is performed. Note that the function f is set such that its calculated value becomes larger as THVOL becomes larger (higher speed) and becomes larger as gear becomes larger (higher speed).

In step # 3, TREV> f (THVO
(L, gear) (YES) Step #
4 sets the slip flag XLSLP (XLSLP =
1) and then step # 6 is executed, while TREV ≦ f
If it is determined to be (THVOL, gear) (NO), the slip flag XLSLP is reset (X
After # LSLP = 0), step # 6 is executed. The slip flag XLSLP is a flag that is set when the operating state is in the operating region where the engaging force control should be performed, and is reset when the operating state is not in the operating region where the engaging force control should be performed.

At step # 6, the slip flag XLS is set.
It is determined whether or not LP is greater than 0, that is, whether or not it is set, and when it is determined that XLSLP> 0 (YES), step # 7 to step # 28 and step # 37 to step # 39. Thus, the engagement force control of the lockup clutch 29 is performed. Specifically, first in step # 7, the engine torque TN and the turbine speed TR are set.
The target differential pressure PSL is calculated using a predetermined function g based on the EV and the gear gear (PSL = g (TN, TRE
V, gear)). Here, for the function g, for example, the calculated value is TN
Is set to be larger as is larger, as TREV is larger, and is larger as gear is larger (high speed stage).

Next, at step # 8, the shift flag SFT is set.
It is determined whether UP is greater than 0, that is, whether gear change is in progress. Here, if it is determined that SFTUP ≦ 0 (NO), that is, if it is determined that it is not during gear shifting, the normal operation is performed in steps # 9 to # 22.
The fastening force control (for non-shift) is performed. In this case, first, in step # 9, the previous fluid differential pressure deviation (DLUP [i-1]
It is determined whether or not the absolute value abs (DLUP [i-1] -PSL) of -PSL) is larger than a predetermined first limit differential pressure deviation KESPO1. Here, the first limit differential pressure deviation KESPO1
Is set to a limit such that when the absolute value of the fluid differential pressure deviation becomes larger than this, the feedback control cannot quickly converge the input / output rotational speed difference to the target rotational speed difference.

At step # 9, abs (DLUP [i-1]-
When it is determined that PSL)> KESPO1 (YE
S), that is, the fluid differential pressure DLUP [i-1] is the target differential pressure PS
If it is determined that it is significantly deviated from L, it is determined in step # 10 whether DLUP [i-1] is larger than PSL. Here, DLUP [i-1]> PSL is normally when the lock-up mode is shifted to the slip mode during non-shifting, and DLUP [i-].
1] ≦ PSL when the converter mode is switched to the slip mode.

At step # 10, DLUP [i-1]> P
If it is determined to be SL (YES), step # 1
1, the fluid differential pressure DLUP [i] is (PSL + KESPO
1) (DLUP [i] = PSL + KESPO1). That is, the fluid pressure difference DLUP [i] suddenly becomes (PSL + KES
It is reduced stepwise until PO1). On the other hand, if it is determined in step # 10 that DLUP [i-1] ≤PSL is satisfied (NO), then in step # 12, the current fluid pressure difference DL
UP [i] is set to (PSL-KESPO1) (DLUP
[i] = PSL-KESPO1). That is, the fluid pressure difference DL
UP [i] is increased stepwise to (PSL-KESPO1) at a stroke. Thus, when the fluid differential pressure is extremely high or low, the fluid differential pressure is suddenly (PSL + K
Since it is changed stepwise to (ESPO1) or (PSL-KESPO1), the fluid differential pressure deviation is rapidly reduced, the rotational speed deviation is rapidly reduced accordingly, and the input / output rotational speed difference (NE-TREV). Quickly converges to the target speed difference
(Following), the responsiveness of the fastening force control is enhanced. Of course, the larger the fluid pressure difference, the smaller the input / output rotation speed difference, and conversely, the smaller the fluid pressure difference, the larger the input / output rotation speed difference. Step #
After step 11 or step # 12 is executed, steps # 37 to # 39 described later are executed.

At step # 9, abs (DLUP [i-1]-
If it is determined that (PSL) ≦ KESPO1, (N
O), the absolute value abs of the previous fluid differential pressure deviation in step # 13
It is determined whether (DLUP [i-1] -PSL) is larger than a predetermined second limit differential pressure deviation KESPO2. here,
The second limit differential pressure deviation KESPO2 is a value smaller than the first limit differential pressure deviation KESPO1, and when the absolute value of the fluid differential pressure deviation becomes smaller than this, the fluid differential pressure exceeds the target differential pressure PSL. The limit is set so that a phenomenon, so-called overshoot occurs.

At step # 13, abs (DLUP [i-1]
-PSL)> KESPO2 (YE
S), that is, the fluid pressure difference DLUP [i-1] is (PSL +
Between KESPO1) and (PSL + KESPO2), or
When it is determined that it is between (PSL-KESPO1) and (PSL-KESPO2), it is determined in step # 14 whether DLUP [i-1] is larger than PSL.

At step # 14, DLUP [i-1]> P
If it is determined to be SL (YES), step # 1
In (5), (DLUP [i-1] -KEDON1) is set as the current fluid pressure difference DLUP [i] (DLUP [i] = DLUP [i-1].
-KEDON1). That is, the fluid differential pressure DLUP
[i] is reduced by the first differential pressure change amount KETON1 from the previous fluid differential pressure DLUP [i-1]. Therefore, when this step # 15 is repeated, the fluid differential pressure DLUP [i] becomes KE.
The rate of change (slope) corresponding to DON1 is reduced. It should be noted that the first differential pressure change amount KETON1 has a larger change rate of the fluid differential pressure (change rate of the control amount) than the average change rate of the fluid differential pressure during feedback control of the fluid differential pressure, which will be described later. Is set to a value that

In step # 14, DLUP [i-1] ≤PS
If it is determined to be L (NO), in step # 16.
(DLUP [i-1] + KEDN2) is the current fluid pressure difference D
LUP [i] (DLUP [i] = DLUP [i-1] + K
EDON 2). That is, the current fluid pressure difference DLUP [i] is increased by a predetermined second differential pressure change amount KETON2 from the fluid pressure difference DLUP [i-1] of the previous time. Therefore, when this step # 16 is repeated, the fluid pressure difference is increased. DLUP [i] is K
It will be increased at the rate of change (slope) corresponding to EDON2. The second differential pressure change amount KETON2 is set to a value such that a larger rate of change in the fluid pressure difference than the average rate of change in the fluid pressure difference during feedback control of the fluid pressure difference, which will be described later, is obtained. It

As described above, when the fluid differential pressure approaches the target differential pressure PSL after the fluid differential pressure is first changed stepwise, the fluid differential pressure changes toward the target differential pressure PSL by the predetermined change. Since it can be changed by the rate, the fluid pressure differential deviation can be reduced rapidly without causing overshoot, and the rotation speed deviation can be reduced rapidly, and the input / output rotation speed difference (NE-TREV ) Can be quickly converged (followed) to the target rotational speed difference, and the responsiveness of the fastening force control can be improved. After step # 15 or step # 16 is executed, steps # 37 to # 39 described later are executed.

At step # 13, abs (DLUP [i-1]
If it is determined that −PSL) ≦ KESPO2, (N
O), input / output speed difference (NE-TRE in step # 17)
V) of the target rotational speed difference KEDN1, that is, the absolute value abs (NE-TREV-KEDN1) of the rotational speed deviation is larger than a predetermined reference rotational speed deviation KEDN2. Here, if the absolute value of the rotational speed deviation is larger than the reference rotational speed deviation KEDN2, the feedback control causes the input / output rotational speed difference (NE-TREV) to quickly converge (follow) to the target rotational speed difference KEDN1. Is set to a limit that makes it difficult.

At step # 17, abs (NE-TREV-
When it is determined that KEDN1)> KEDN2 (YE
S), that is, when it is determined that the rotation speed deviation has not yet been reduced to the extent that the response (following) of the feedback control can be sufficiently secured, step # 1
At 8, it is determined whether (NE-TREV-KEDN1) is greater than 0, that is, whether the input / output rotational speed difference (NE-TREV) is greater than the target rotational speed difference KEDN1.

In step # 18, (NE-TREV-K
If it is determined that EDN1)> 0 (YES), that is, if the input / output rotational speed difference is larger than the target rotational speed difference, then in step # 19, (DLUP [i-1] + KEDON
3) is the fluid differential pressure DLUP [i] of this time (DLUP [i]
= DLUP [i-1] + KEDON3). That is, the fluid pressure difference DLUP [i] is increased from the last fluid pressure difference DLUP [i-1] by the predetermined third differential pressure change amount KETON3, and thus the input / output rotational speed difference is reduced. When this step # 19 is repeated, the fluid pressure difference D
LUP [i] is increased at the rate of change (slope) corresponding to KEDON3, and the input / output rotational speed difference is gradually reduced accordingly. The third differential pressure change amount KETON3 is
Although smaller than the second differential pressure change amount KETON2 described above, it is larger than the average change rate of the fluid differential pressure during feedback control of the input / output rotational speed difference, which will be described later, (the control amount of the control amount). The rate of change is set to a value that can be obtained.

At step # 18, (NE-TREV-K
When it is determined that EDN1) ≦ 0 (NO), that is, when the input / output speed difference is less than or equal to the target speed difference,
At step # 20, (DLUP [i-1] -KETON4) is set as the current fluid pressure difference DLUP [i] (DLUP [i] = D
LUP [i-1] -KEDON 4). That is, the current fluid pressure difference DLUP [i] is reduced from the last fluid pressure difference DLUP [i-1] by the predetermined fourth differential pressure change amount KETON4, and thus the input / output rotational speed difference is increased. . When this step # 20 is repeated, the fluid pressure difference DL
UP [i] is reduced at a rate of change (slope) corresponding to KEDON4, and the input / output rotational speed difference is gradually increased accordingly. It should be noted that the fourth differential pressure change amount KETON4 is smaller than the first differential pressure change amount KETON1 described above, but is lower than the average change rate of the fluid differential pressure during feedback control of the input / output speed difference, which will be described later. The value is set so that a large change rate of the fluid pressure difference can be obtained. As described above, during the feedforward control of the fluid pressure difference based on the target pressure difference, as the fluid pressure difference approaches the target pressure difference, the rate of change of the fluid pressure difference, that is, the rate of change of the control amount is switched to a successively smaller value. Therefore, the phenomenon that the fluid pressure difference exceeds the target pressure difference, that is, the occurrence of overshoot, is effectively prevented. After Step # 19 or Step # 20 is executed, Step # 37 to Step # which will be described later.
39 is executed.

At step # 17, abs (NE-TREV-
When it is determined that KEDN1) ≦ KEDN2 (N
O), that is, when it is determined that the rotation speed deviation has been reduced to such an extent that the feedback response (following performance) of the input / output rotation speed difference can be sufficiently secured, the rotation speed is determined in step # 21. Number deviation (NE-TREV-KEDN
1) is set as the control deviation dtrev, and subsequently, in step # 22, the current fluid pressure difference DLUP [i] is calculated based on the control deviation dtrev by the following equation 1.

## EQU1 ## DLUP [i] = k (dtrev) + ∫j (dtrev) dt + C [i-1] + PSL ... Equation 1 Note that in Equation 1, k is a function representing a proportional operation characteristic in feedback control. , J are functions that represent integral operation characteristics in feedback control. Further, C is calculated in step # 37 described later,
It is the fluid pressure difference deviation when shifting to the feedback control.

As is clear from the equation 1, in this case, the fluid pressure difference DLUP [i] basically decreases the control deviation dtrev by the proportional operation and the integral operation according to the control deviation dtrev, that is, the rotational speed deviation. The correction is performed based on the fluid differential pressure deviation C. That is, so that the input / output speed difference follows the target speed difference,
Feedback control of the input / output rotational speed difference is performed using the fluid differential pressure as a control amount. Further, in this feedback control, since the correction is performed based on the fluid differential pressure deviation at the time of shifting to the feedback control, the input / output rotational speed difference can be controlled from both aspects of the rotational speed difference and the fluid differential pressure deviation. Therefore, the responsiveness (following performance) of feedback control of the input / output speed difference is significantly improved. This step #
After step 22 is executed, step # 38 to step # 3
9 is executed. In the feedback control of the input / output rotational speed difference, the correction may be performed not based on the fluid differential pressure deviation at the time of shifting to the feedback control, but on the basis of the fluid differential pressure deviation that is changing every moment. In this case, after step # 22 is executed, steps # 37 to # 39 may be executed.

As described above, in the normal time (non-shift), the steps # 11 and # 1 are performed depending on the driving condition.
2, step # 15, step # 16, step # 1
In step 9, step # 20 or step # 22, the current fluid pressure difference DLUP [i], that is, the fluid pressure difference to be set this time is calculated. The fluid pressure difference DLUP [i] is calculated in steps # 37 to # 37. In # 39, the duty ratio DUTY is converted, the duty ratio DUTY is output to the second solenoid valve 18, and the actual fluid pressure difference (engagement force) applied to the lockup clutch 29 is set.
It will be held in P [i].

Specifically, in step # 37, the fluid differential pressure deviation C used in step # 22 is calculated by subtracting the target differential pressure PSL from the fluid differential pressure DLUP [i] (C = DLUP [i] -PSL). continue,
In step # 38, the fluid deviation DLUP is calculated by the following equation 2.
The duty ratio DUTY corresponding to [i] is calculated.

EQUATION 2 DUTY = x ₁ (DLUP, THOIL, PL) + x ₂ (Vb, THOIL) Equation 2 In Equation 2, x ₁ is fluid differential pressure DLUP [i], oil temperature THOIL, and line pressure PL. Is a predetermined function for converting the fluid pressure difference DLUP [i] into a duty ratio DUTY, where and are independent variables. X ₂ is the battery voltage Vb
Fluid differential pressure DLU with oil temperature and oil temperature THOIL as independent variables
This is a predetermined function for performing correction when converting P [i] into the duty ratio DUTY.

Here, the duty ratio DUTY is, specifically, a first duty ratio map having DLUP, THOIL, and PL stored in the memory of the control unit C as parameters, and Vb and THOIL. By searching the second duty ratio map as a parameter, the value of x ₁ (DLUP, THOIL, PL) and x ₂
The value of (Vb, THOIL) is calculated, and the two are added to perform the calculation. Thus, the duty ratio DU
The duty ratio map for calculating TY is divided into the first and second duty ratio maps, because the memory capacity for storing the map increases if the number of parameters of one function is too large. Is. That is, the capacity of the control unit C can be reduced by dividing the duty ratio map into two in this way. The duty ratio map may be divided into three to further reduce the memory capacity. In this case, the duty ratio DUTY is expressed by the following Expression 3, for example.

EQUATION 3 DUTY = x ₁ '(DLUP, THOIL) + x ₂ ' (PL, THOIL) + x ₃ '(Vb, THOIL) ……………………………………

Further, the duty ratio DUTY based on the equation 2
In the above calculation, the control amount is corrected based on the line pressure, that is, the original pressure of the hydraulic mechanism 40. When the line pressure fluctuates or changes, the fluid differential pressure fluctuates or changes in accordance with the fluctuation or change. This is to prevent the above and thereby improve the control accuracy of the feedback control of the input / output speed difference. After step # 39 is executed, the process returns to step # 1.

FIG. 8 shows the fluid differential pressure DLUP (graph G ₁ ) and the feedback control on / off state (graph G ₂ when the operating state is changed from the converter mode to the slip mode and the engagement force control is started. ), Fluid differential pressure deviation
(Graph G ₃ ) and slip flag XLSLP set
An example of change characteristics of the reset state (graph G ₄ ) with respect to time is shown. In the example shown in FIG. 8, at time t ₁ , the operating state shifts from the converter mode to the slip mode, the feedforward control of the fluid pressure difference based on the target pressure difference is started, and at time t ₂ , the change rate of the fluid pressure difference changes. The feedback control of the input / output rotational speed difference is started with the fluid pressure difference as the control amount, such as switching (reduced) and making the input / output rotational speed difference follow the target rotational speed difference at time t ₃ . More specifically, at time t ₁ , the absolute value of the fluid differential pressure deviation is larger than KESPO1, so step # 12 is executed and the fluid differential pressure is increased to (PSL-KESPO1) all at once, and then step # 16 is repeatedly executed. The fluid differential pressure is increased at a rate of change corresponding to KETON2 (the input / output rotational speed difference decreases). Then, at time t ₂ , the absolute value of the fluid pressure difference is KES.
PO2 next, t ₂ after is repeatedly executed step # 19, it is enhanced by a small rate of change than the period of the change rate i.e. t ₁ ~t ₂ differential fluid pressure corresponding to KEDON3
(The input / output speed difference decreases). The absolute value abs of the rotational speed deviation at time _{t 3 (NE-TREV-KEDN1} ) is KE
Since it becomes DN2 or less, step # 21 to step # 22 are executed, and the feedback control of the input / output rotational speed difference using the fluid differential pressure as the control amount is started.

In this way, when the converter mode is shifted to the slip mode and the fastening force control is started, the fluid differential pressure is first increased stepwise by the feedforward control, and then at a relatively large change rate. Since the fluid differential pressure is increased toward the target differential pressure, the input / output rotational speed difference can be quickly brought close to the target rotational speed difference. Then, after this, when the fluid differential pressure approaches the target differential pressure, the rate of change of the fluid differential pressure is reduced, so that no overshoot occurs. After that, when the input / output rotational speed difference approaches the target rotational speed difference, feedback control of the input / output rotational speed difference is started, and the input / output rotational speed difference is held at the target rotational speed difference.
Thus, the responsiveness at the time of starting the engagement force control can be enhanced, and the control accuracy of the engagement force control can be enhanced.

By the way, in the step # 8, the SFTU
If it is determined that P> 0 (YES), step #
In 23 to step # 28, the engagement force control for shifting is performed. Specifically, first, at step # 23, the rate of change dTREV of the turbine rotation speed TREV with respect to time is set to a predetermined value DR.
It is determined whether it is smaller than EN1. Where DRE
N1 is set to a value at which it can be determined that the turbine rotational speed TREV (gear ratio) has actually begun to change along with the gear shifting operation during gear shifting. That is, in step # 23, it is determined whether or not the gear ratio has started to change during shifting, that is, whether or not substantial shifting has started.

At step # 23, dTREV> DREN
If it is determined to be 1 (YES), that is, if it is determined that the gear ratio has not changed due to the gear shift and therefore the substantial gear shift has not yet started, the previous time is determined in step # 24. The fluid pressure difference DLUP [i-1] of is set as the current fluid pressure difference DLUP [i] (DLUP [i]
= DLUP [i-1]). That is, dTREV ≦ DREN1
Until it becomes, the fluid differential pressure DLUP [i] is held at a constant value. After step # 24 is executed, the above steps # 37 to # 39 are executed.

At step # 23, dTREV≤DREN
If it is determined to be 1 (NO), that is, if it is determined that the gear ratio has begun to change and substantial gear shifting has started, the absolute value of the previous fluid differential pressure deviation is determined in step # 25.
It is determined whether or not abs (DLUP [i-1] -PSL) is larger than a predetermined gear shift limit differential pressure deviation KESF1. Here, when the absolute value of the fluid differential pressure deviation becomes larger than the absolute value of the fluid differential pressure deviation during gear shifting, it is difficult for the gear shift limit differential pressure deviation KESF1 to quickly converge the input / output rotational speed difference to the target rotational speed difference in the feedback control. The limit is set so that

At step # 25, abs (DLUP [i-1]
-PSL)> when it is determined that KESF1 (YE
S), that is, the fluid differential pressure DLUP [i-1] is the target differential pressure PS
If it is determined that it is significantly deviated from L, it is determined in step # 26 whether DLUP [i-1] is larger than PSL. In step # 26, DLUP [i-1]> P
If it is determined to be SL (YES), step # 2
(PSL + KESF1) is the current fluid pressure difference DLUP
[i] (DLUP [i] = PSL + KESF1). That is, the fluid pressure difference DLUP [i] is suddenly (PSL + KESF
It is reduced stepwise until 1). On the other hand, step # 2
When it is determined in step 6 that DLUP [i-1] ≤PSL (NO), (PSL-KESF1) is set as the current fluid pressure difference DLUP [i] in step # 28 (DLUP [i] = PS
L-KESF1). That is, the fluid pressure difference DLUP [i] is increased in a stepwise manner up to (PSL-KESF1). Thus, when the fluid pressure difference is extremely high or low, the fluid pressure difference is suddenly (PSL + KESF1) or
Since (PSL-KESF1) is changed stepwise, a large fluid differential pressure deviation caused by a gear shift is rapidly reduced, and accordingly, a rotational speed deviation is rapidly reduced.
Input / output speed difference (NE-TREV) is the target speed difference KED
N1 is quickly converged (followed), and the responsiveness of the fastening force control is enhanced.

After step # 27 or step # 28 is executed, step # 37 to step # 39 are executed. In step # 25, abs (DLUP [i-1]
If it is determined that −PSL) ≦ KESF1, then (N
O), Step # 13 to Step # 22 are executed, and the same fastening force control as the normal time (non-shift) fastening force control is performed.

FIG. 9 shows a set / reset state of the fluid differential pressure DLUP (graph G ₅ ) and the shift flag SFTUP (graph G ₅ ) when a shift (shift up) from the 2nd speed to the 3rd speed occurs during engagement force control. G ₆ ), the on / off state of the shift flag (graph G ₇ ), the gear ratio (graph G ₈ ), and the gear position (graph G ₉ ) with respect to time are shown as an example. In the example shown in FIG. 9, the output shift signal at time t _4, the feed forward control of the fluid pressure differential gear ratio based on the changed first target differential pressure is started at time t _5, the fluid pressure difference at time t ₆ The change rate of is changed (decreased), and at time t ₇ , feedback control of the input / output rotational speed difference that makes the input / output rotational speed difference follow the target rotational speed difference and uses the fluid pressure difference as the control amount is started. .

In the example shown in FIG. 9, dTR is set during the period from t _{4 to} t _5.
Since EV <DREN1, step # 24 is executed to maintain the fluid differential pressure at a constant value, and at time t ₅ , dTREV.
≧ DREN1 and the absolute value of the fluid pressure difference is KES
Since it is larger than F1, step # 28 is executed to increase the fluid pressure differential step by step to (PSL-KESF1), and after t _5, step # 16 is repeatedly performed, and the fluid pressure differential changes greatly corresponding to KEDON2. It is being raised at a rate. Then, at time t ₆ , the absolute value of the fluid differential pressure is KES.
Becomes PO2 less, t ₆ after the step # 19 is repeatedly executed, are enhanced by a small change rate differential fluid pressure corresponding to KEDON3. Further, the rotation speed deviation at time t ₇ becomes KEDN2 following steps # 21 through Step # 2
2 is executed and feedback control of the input / output speed difference is started.

In this way, when the gear shift is performed during the engagement force control, the fluid differential pressure is first increased stepwise by the feedforward control, and then the fluid differential pressure is increased at a relatively large rate of change to the target differential pressure. Since it can be increased toward, the input / output rotational speed difference can be quickly brought close to the target rotational speed difference. Then, after this, when the fluid differential pressure approaches the target differential pressure, the fluid differential pressure is increased at a small change rate, so that no overshoot occurs. After that, when the input / output rotational speed difference approaches the target rotational speed difference, feedback control of the input / output rotational speed difference is started, and the input / output rotational speed difference is held at the target rotational speed difference. Thus, the responsiveness and control accuracy of the fastening force control can be improved.

By the way, in step # 6, XLSL is used.
When it is determined that P ≦ 0 (NO), that is, when the fastening force control is stopped, steps # 29 to # 36 are executed. Note that Step # 29 to Step # 36 show the control method when the operating state shifts from the slip mode to the converter mode. Specifically, first, at step # 29, the target differential pressure PSL is set to 0 (PSL = 0).

Next, at step # 30, it is determined whether or not the previous slip flag XLSLP [i-1] is larger than 0 and the current slip flag XLSLP [i] is 0, that is, the converter mode is started from this time. It is determined whether or not. Where XLSLP [i-1]> 0 and X
When it is determined that LSLP [i] = 0 (YES), that is, when it is determined that the converter mode has been shifted from this time, the previous fluid differential pressure DLUP [i is determined in step # 31.
-1] is stored (stored), the stored fluid pressure difference is set as the storage pressure difference MSLP, and step # 32 is subsequently executed. In step # 30, XLSP [i-1]> 0
And when it is determined that XLSLP [i] = 0 is not satisfied (N
O), that is, if it is determined that the converter mode has already been entered before the previous time, step # 31 is skipped and step # 32 is executed.

At step # 32, (MSLP-DLU
P [i-1]) is larger than a predetermined first reference differential pressure deviation KESLOF1 and it is determined here (MSLP-DLU).
When it is determined that P [i-1])> KESLOF1,
(YES), and in step # 33 (MSLP-DLU
It is determined whether or not P [i-1]) is larger than a predetermined second reference differential pressure deviation KESLOF2.

In this control, when shifting from the slip mode to the converter mode and the fastening force control is stopped,
The first reference differential pressure deviation KESLOF in which the fluid differential pressure decrease amount is predetermined
When it is 1 or less, the fluid differential pressure is reduced at a small change rate (slope) corresponding to the relatively small first reference change amount KEDOF1 to prevent the occurrence of switching shock. Then, when the fluid differential pressure decrease amount exceeds KEDOF1, the fluid differential pressure is set to a relatively large second reference change amount KE.
The rate of change (gradient) corresponding to DOF2 is rapidly lowered to quickly switch the transmission mode. The amount of decrease in the fluid differential pressure is the predetermined second reference differential pressure deviation K.
When ESLOF2 is exceeded, there is no risk of switching shock, so the fluid pressure difference is reduced to 0 at once.

Thus, in step # 32, (MSLP
-DLUP [i-1]) ≤ KESLOF1 (NO), the fluid differential pressure DL at this time is determined in step # 36.
UP [i] is KED more than the previous fluid differential pressure DLUP [i-1]
It is reduced by OF1. When this step # 36 is repeatedly executed, the fluid pressure difference DLUP [i] becomes KEDO.
It decreases at a small rate of change corresponding to F1.

In step # 32, (MSLP-DLUP [i
−1])> KESLOF1 (YES), and (MSLP-DLUP [i−1]) ≦ K in step # 33.
If it is determined to be ESLOF2 (NO), the current fluid pressure difference DLUP [i] is reduced by KEDOF2 from the last fluid pressure difference DLUP [i-1] in step # 35. When this step # 35 is repeatedly executed, the fluid pressure difference DLUP [i] decreases at a large rate of change corresponding to KEDOF2.

At step # 33, (MSLP-DLUP
[i-1])> When it is determined that KESLOF2
(YES), the fluid differential pressure DLUP [i] is 0 in step # 34.
It is lowered in steps at once, and it becomes a torque conversion state completely. Step # 34, Step # 35
Alternatively, after step # 36 is executed, the above steps # 37 to # 39 are executed.

FIG. 10 shows an example of a change characteristic of the fluid differential pressure with respect to time when shifting from the slip mode to the converter mode (graph G ₁₀ ). In the example shown in FIG. 10, the switching signal is output at time t ₈ from the sleep mode to the converter mode, and transition to full torque conversion state at time t _9.

Although not described in the flow charts shown in FIGS. 4 to 7, the fluid differential pressure DLUP (graph G ₁₁ ) and the lock-up on / off state at the time of shifting from the converter mode to the lock-up mode. FIG. 11 shows an example of change characteristics of (graph G ₁₂ ) and the set / reset state of the lockup flag (graph G ₁₃ ) with respect to time. In the example shown in FIG. 11, the lockup flag is set at time t ₁₀ , the fluid pressure difference is stepwise increased to a value lower than the target pressure difference by a predetermined value α, and then increased at a relatively large rate of change. ing. Then, at time t ₁₁ when the fluid differential pressure reaches a value lower than the target differential pressure by a predetermined value β (<α), the change rate is switched to a relatively small value, and after the fluid differential pressure exceeds the target differential pressure. at time t _12, the fluid differential pressure is increased to a maximum fluid pressure differential (max) once stepwise.

During the engagement force control, the torque converter 2 or the speed change gear mechanism 3 fails, the N range or the R range is selected, or the engine speed is abnormally lowered. In the case of prohibition, as shown in FIG. 12, the fluid differential pressure (graph G ₁₄ ) is immediately decreased to 0 at a instant t ₁₃ when the prohibition signal is output.

As described above, according to the present embodiment, even when the engagement force control of the lockup clutch 29 is started, or when the gear shift is performed during the engagement force control, the input / output speed difference can be quickly changed to the target rotation speed. Can be converged (followed) to a number difference,
The responsiveness and control accuracy of the fastening force control are effectively enhanced.
In this embodiment, the change characteristic of the control amount of the fluid differential pressure (K
ESPO1, KESPO2, KEDON1, KEDON
2, KEDON3, KEDON4, KESF1, KES
LOF1, KESLOF2, KEDOF1, KEDOF
(2 etc.) is individually set according to the operating state (for example, whether or not the engagement force control is started or stopped, whether or not the engine load changes, whether or not there is a gear change, etc.). Precision is greatly improved.

[0083]

According to the first aspect of the invention, first, the difference between the rotational speed of the driving side rotating member and the rotational speed of the driven side rotating member.
When the (input / output rotational speed difference) exceeds a predetermined value, the fluid differential pressure is controlled based on the target differential pressure set according to the input torque and the rotational speed of the driven side rotating member. The rotational speed difference can be quickly converged (followed) to the target rotational speed difference, and the responsiveness of the fastening force control is enhanced. Further, when the input / output rotational speed difference is less than or equal to the predetermined value, feedback control is performed so that the input / output rotational speed difference follows the target rotational speed difference. Therefore, the input / output rotational speed difference should be maintained at the target rotational speed difference. Therefore, the control accuracy of the fastening force control can be improved.

[0084] the of et, as the fluid pressure differential approaches the target differential pressure, the control rate of change of the fluid pressure differential is smaller, does not occur overshoot with respect to the target differential pressure of the fluid pressure differential, the fastening force The control accuracy of control is further improved.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the difference between the target differential pressure and the fluid differential pressure (fluid differential pressure deviation) at the time of starting the engagement force control is reflected in the feedback control of the input / output speed difference, the control accuracy of the feedback control of the input / output speed difference. Is increased.

According to the third invention, basically the same action and effect as those of the second invention can be obtained. Further, the change characteristic of the control amount of the fluid differential pressure is changed between when the engagement force control of the lockup clutch is started and when it is stopped, and is changed according to the presence or absence of a change in engine load and the presence or absence of gear shift. Therefore, the fastening force can be appropriately controlled according to the operating state, and the control accuracy of the fastening force control is further enhanced.

According to the fourth invention, basically the same action and effect as the third invention can be obtained. Further, since the control amount of the fluid differential pressure is corrected according to the original pressure of the fluid, even if the original pressure of the fluid changes or changes, the fluid differential pressure does not change or change. For this reason. The control accuracy of the fastening force control is further enhanced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of first to fourth inventions corresponding to claims 1 to 4 .

FIG. 2 is a system configuration diagram of a power train including a fastening force control device according to the present invention.

FIG. 3 is a system configuration diagram of the torque converter of the power train shown in FIG. 2 and a hydraulic mechanism thereof.

FIG. 4 is a part of a flowchart showing a control method of lockup clutch control (engagement force control).

FIG. 5 is a part of a flowchart showing a control method of lockup clutch control (engagement force control).

FIG. 6 is a part of a flowchart showing a control method of lockup clutch control (engagement force control).

FIG. 7 is a part of a flowchart showing a control method of lock-up clutch control (engagement force control).

FIG. 8 is a diagram showing a case where the fluid differential pressure and feedback control are turned on / off during the transition from the converter mode to the slip mode
It is a figure which shows a time-dependent change of an OFF state, a fluid differential pressure deviation, and a slip flag.

FIG. 9 shows a fluid pressure difference, a set / reset state of a shift flag, when a shift is performed during engagement force control,
FIG. 6 is a diagram showing a change over time of an on / off state of a shift flag, a gear ratio, and a shift speed.

FIG. 10 is a diagram showing a change over time in a fluid pressure difference when shifting from a slip mode to a converter mode.

FIG. 11 is a diagram showing changes over time in the fluid pressure difference, the lockup state, and the set / reset state of the lockup flag at the time of transition from the converter mode to the lockup mode.

FIG. 12 is a diagram showing a change over time in a fluid differential pressure when an engagement force control prohibition signal is output during engagement force control.

[Explanation of symbols]

PT ... powertrain C ... Control unit 1 ... engine 2 ... Torque converter 3 ... Speed change gear mechanism 8 ... Air flow sensor 11 ... Throttle opening sensor 12 ... Turbine speed sensor 13 ... Engine speed sensor 14 ... Oil temperature sensor 15 ... Oil pressure sensor 17, 18 ... First and second solenoid valves 23 ... Pump 24 ... Turbine 29 ... Lockup clutch

Continuation of front page (56) Reference JP-A-3-61761 (JP, A) JP-A-60-143266 (JP, A) JP-A-2-195072 (JP, A) JP-A-62-270864 (JP , A) Japanese Patent Publication Sho 63-13060 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 61/14

Claims (4)

(57) [Claims] 1. A driving-side rotating member that is rotationally driven by a driving source, a driven-side rotating member that is rotationally driven by the driving-side rotating member through a fluid, and a fastening force corresponding to a fluid differential pressure applied. In a fastening force control device for a fluid coupling, which is provided with a lock-up clutch that can fasten a driving side rotating member and a driven side rotating member, an input torque detection for detecting a torque input to the driving side rotating member. Means, a drive-side rotation speed detection means for detecting the rotation speed of the drive-side rotation member, a driven-side rotation speed detection means for detecting the rotation speed of the driven-side rotation member, and a rotation speed and a rotation speed of the driving-side rotation member. When the difference in the number of rotations of the driving side rotating member exceeds a predetermined value, the fluid pressure difference applied to the lockup clutch is set to the input torque detected by the input torque detecting means and the driven side number of rotations detecting hand. Fluid differential pressure control means for controlling based on the target differential pressure set according to the rotational speed of the driven-side rotating member detected by, and the rotational speed when the difference between the rotational speeds is less than or equal to the predetermined value. Feedback control means for feedback-controlling the fluid pressure difference applied to the lock-up clutch is provided so that the difference between the fluid pressure difference follows a predetermined target rotation speed difference, and the fluid pressure difference control means changes the fluid pressure difference to the target pressure difference. Approaching
Set the rate of change of the fluid differential pressure control amount to a small value.
It is in the engagement force control apparatus for a fluid coupling according to claim. 2. The fluid coupling fastening force control device according to claim 1, wherein the feedback control means feeds back a difference between the target differential pressure and the fluid differential pressure applied to the lockup clutch at the time of transition to the feedback control. A fastening force control device for a fluid coupling, which is adapted to be reflected in control. 3. The fastening force control device for a fluid coupling according to claim 2 , wherein the fluid differential pressure control means determines the change characteristic of the controlled variable of the fluid differential pressure,
Fastening of a fluid coupling characterized in that it is changed when starting and stopping engagement force control of the lockup clutch, and is changed depending on whether or not there is a change in engine load and whether or not there is a shift. Force control device. 4. The fastening force control device for a fluid coupling according to claim 3 , wherein the fluid differential pressure control means and the feedback control means control the fluid differential pressure applied to the lockup clutch in accordance with the change of the source pressure of the fluid. A fastening force control device for a fluid coupling, wherein a controlled amount of a fluid differential pressure is corrected according to a source pressure of fluid so as not to change.