JP2003176869A - Control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an automatic transmission capable of controlling a transfer to the pseudo neutral state while a stability and a responsiveness are compatible in the control device for the automatic transmission forming the pseudo neutral state. <P>SOLUTION: When execution conditions for excessive/steady control are effected at the time t1, Sty<SB>-</SB>1 control for gradually making the target slip amount small is executed. In the case where a slip as the engagement state of the clutch is generated at the time t2 in this state, Sty<SB>-</SB>2 control is started and the target slip amount is set as a secondary function. Thereafter, if the target slip amount arrives at the final target slip amount at the time t3, the target slip amount after that is set to the fixed state. Thereafter, the target slip amount is subsequently fixed to the final target slip amount at the time t4. Therefore, the responsiveness and the stability are compatible to realize a transfer to the pseudo neutral state by setting the target slip amount corresponding to the advancement state of the control. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission that carries out pseudo-neutral control.

[0002]

2. Description of the Related Art In an automatic transmission for automobiles, the power of an engine is transmitted to an input shaft of a speed change mechanism via a torque converter, the speed change mechanism is used to shift the speed, and the power is transmitted to an output shaft to rotationally drive a drive shaft. I have to. The most common speed change mechanism is to arrange a plurality of gear elements between an input shaft and an output shaft to form a plurality of power transmission paths having different speed ratios between the input shaft and the output shaft. Friction engagement and disengagement of clutches and brakes are selectively switched in the transmission path, and the power transmission path between the input and output shafts is switched to switch the gear ratio.

By the way, in such an automatic transmission, a P (parking) range, an R (reverse) range,
N (neutral) range, D (drive) range, S
It is possible to select the (second) range, the L (low) range, or the like. For example, when the N range is switched to the D range by the shift lever, the rotation of the engine in the idling state is performed via the torque converter. The creep phenomenon occurs in which the vehicle is gradually transmitted to the transmission without even depressing the accelerator pedal.

On the other hand, in the technique disclosed in Japanese Patent No. 2804229, the D range, S range, and L range (hereinafter referred to as "forward range") for moving the vehicle forward are selected, and the accelerator pedal is used. When the vehicle is released, the brake pedal is depressed, and the vehicle speed is detected to be substantially "0", the forward clutch, that is, the low clutch, engaged during forward traveling of the transmission is slipped. A technique relating to pseudo neutral control for forming a pseudo neutral state is known.

Generally, the purpose of forming this pseudo neutral state is to reduce the engaging force as the low clutch is engaged to make the slip engagement, thereby reducing the input / output rotational speed difference of the torque converter. To reduce torque loss. That is, it is intended to reduce fuel consumption by reducing torque cross.

By the way, when the accelerator is depressed to return from the pseudo neutral state to the normal operation mode,
If the piston stroke of the low clutch is large, the engine will blow up when the low clutch is re-engaged.
Therefore, in the pseudo neutral state, the piston stroke of the low clutch is set to 0 to suppress the response delay when the low clutch is re-engaged. For this reason, the target engagement area of the low clutch is extremely narrow, and therefore the hydraulic control for controlling the engagement state of the low clutch naturally has a narrow control range.

In the pseudo-neutral control disclosed in Japanese Patent No. 2804229, the input / output rotational speed difference of the torque converter is required to prevent the occurrence of the creep phenomenon during the engine idling operation while the vehicle is running in the D range. The hydraulic pressure supplied to the hydraulic servo of the low clutch is feedback-controlled so that it becomes a predetermined value, and a slip engagement state is formed.

In such a pseudo neutral state, for example, when the accelerator pedal is depressed and the low clutch is re-engaged, an engagement delay occurs due to a loss stroke of the low clutch piston, or the engine is blown dry. It is possible to prevent the occurrence or the occurrence of the engagement shock.

By the way, in the control of the automatic transmission that forms such a pseudo neutral state, when the engine speed shifts to the idle operating state and shifts to the pseudo neutral state, the input side and the output side of the torque converter are changed. The rotation speed difference is in a large state. That is,
When shifting to the pseudo-neutral state, since the low clutch piston is completely engaged, the rotational speed of the output side of the torque converter becomes 0, and the rotational speed difference between the input side and the output side of the torque converter becomes large. However, the control device for an automatic transmission of Japanese Patent No. 0280229 implements the transition to the pseudo neutral state as follows. The hydraulic pressure at which the low clutch piston is completely engaged from the fully engaged state is set in advance, and thereafter, the set pressure ΔP may be changed every time Δt in correspondence with the engine rotation speed Ne. Have been described.

[0010]

However, in such a method of changing the oil pressure of the clutch piston by a predetermined set pressure ΔP, when the set pressure is large, the convergence to the target engagement region is deteriorated. However, when the set pressure is small, the responsiveness to the target engagement area deteriorates.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to improve the responsiveness and stability of the output side rotation speed of the torque converter when shifting to the pseudo neutral state. An object of the present invention is to provide an automatic transmission control device capable of promptly executing the shift to the pseudo neutral state.

[0012]

Therefore, as in the invention of claim 1, in the period in which the vehicle is stopped and the engine is in the idle operation state and then the pseudo neutral state is entered, The target difference rotation speed setting means includes target difference rotation speed changing means for changing the method of setting the target difference rotation speed according to the progress state of the period.

As a result, the method of setting the target differential rotation speed can be changed according to the progress of the transition period, so that the transition to the pseudo-neutral state can be made responsive and stable depending on the progress of control. Both can be controlled with high precision.

Further, as in the second aspect of the present invention, the control gain of the feedback control is changed according to the progress state of the transition period, so that the stability and the responsiveness are made compatible to the pseudo neutral state. The transition of can be performed smoothly.

The transition period described above may be divided into a plurality of sections as in the invention of claim 3, and the target rotation speed may be calculated by a different setting method in each section.

As a result, the target differential rotation speed can be appropriately set for each of the divided sections by a different method.
Both responsiveness and stability are achieved to enable an accurate transition to the pseudo-neutral state.

Further, as a method of setting the target differential rotation speed in the above-mentioned divided section, the target differential rotation speed may be set by a predetermined function as in the invention of claim 4, or The target differential rotation speed may be set by a quadratic function as in the fifth aspect of the invention.

Similarly, in the invention of claim 6, when the actual differential rotation speed calculated by the differential rotation speed calculation means becomes equal to or lower than the target differential rotation speed set by the target differential rotation speed setting means. , From the previous target differential rotation speed, by subtracting a predetermined differential rotation speed that is set within a range in which the hydraulic pressure applied to the forward clutch does not change significantly and the engagement of the forward clutch is advanced early. Set the target differential rotation speed this time.

As a result, the predetermined differential rotation speed does not cause a large fluctuation in the hydraulic pressure applied to the forward clutch, and
Since it is set within a range in which the engagement of the forward clutch is advanced at an early stage, it is possible to smoothly shift to the pseudo neutral state without generating torque shock.

In a seventh aspect of the present invention, in a period in which the vehicle is stopped and the engine is in an idle operation state and then transitions to a pseudo-neutral state, the period is divided into first to fourth periods. The target differential rotation speed setting means gradually reduces the target differential rotation speed in the first period, sets the target differential rotation speed by a function of a plurality of orders in the second period, and In the period and the fourth period, the target differential rotation speed is set to the final target differential rotation speed in the pseudo neutral state.

With this, the target differential rotation speed can be set according to the progress state of the transition period, so that the transition to the pseudo-neutral state can be accurately controlled with both responsiveness and stability. .

Further, in the first to fourth transition periods, as in the invention of claim 8, in the first and third periods, the response is emphasized and the control gain of the feedback control is set to a high gain. However, during the second and fourth periods, the control gain of the feedback control is set to a low gain, placing importance on stability.

With this, the target differential rotation speed can be appropriately set by different methods for each divided period.
Both responsiveness and stability are achieved to enable a systematic transition to a pseudo neutral state.

[0024]

<First Embodiment> A first embodiment of the present invention will be described below with reference to the drawings.

First, a schematic configuration diagram of the automatic transmission 11 will be described with reference to FIGS. 1 and 2. As shown in FIG. 2, the torque converter 12 is provided on the output shaft of the engine (not shown).
The input shaft 13 is connected, and the output shaft 14 of the torque converter 12 is connected to a hydraulically driven transmission gear mechanism 15 (transmission mechanism). Inside the torque converter 12, a pump impeller 31 and a turbine liner 32 that form a fluid coupling are provided to face each other, and a stator 33 that rectifies the flow of oil is provided between the pump impeller 31 and the turbine liner 32. Has been. Pump impeller 31
Is connected to the input shaft 13 of the torque converter 12, and the turbine liner 32 is connected to the output shaft 1 of the torque converter 12.
Connected to four.

Further, the torque converter 12 is provided with a lockup clutch 16 for engaging or disengaging between the input shaft 13 side and the output shaft 14 side. The crankshaft 13, which is the output shaft from the engine,
It is transmitted to the turbine shaft 14 via the torque converter 12. The turbine shaft 14 has a transmission gear mechanism 15
The gear ratio of the gear shift mechanism 15 is switched by switching between a plurality of clutches and each brake in the front planetary gear 23 and the rear planetary gear 22 of the shift gear mechanism 15. on the other hand,
The reduction drive shaft 35 includes the ring gear of the front planetary gear 23 and the rear planetary gear 2.
It is connected to two carriers.

A reverse clutch RC, a high clutch HC, and a low clutch LC are provided as each clutch which is a friction engagement element for switching a plurality of shift speeds in the two planetary gears 22 and 23, and each brake is a 2 & 4 brake. B0, low & reverse B1, and low one-way clutch 34 are provided.

Incidentally, FIG. 3 shows the clutch R of the 4-speed automatic transmission.
The combination of C, HC, LC, and the engagement of the brakes B0, B1 is shown. The circles indicate the clutches and brakes that are held in the engaged state (torque transmission state) at the gear position, and the unmarked release. It shows the state. Also, the ⊚ mark indicates that the engagement is made only at the time of the corresponding drive, and
The mark indicates that it is released only when the vehicle starts moving and is engaged when the vehicle speed exceeds a predetermined speed. For example, in the case of downshifting from the third speed to the second speed, by releasing the clutch HC of the two clutches HC and LC held in the engaged state at the third speed and newly engaging the brake B0. Downshift to second gear. When shifting up from the 3rd speed to the 4th speed, one of the two clutches HC and LC held in the engaged state at the 3rd speed is released, and the brake B0 is used instead. 4 by engaging
Shift up fast.

As shown in FIG. 1, the speed change gear mechanism 15 includes
A hydraulic pump 18 driven by engine power is provided,
A hydraulic control circuit 17 is provided in an oil pan (not shown) that stores hydraulic oil. The hydraulic control circuit 17 includes a line pressure control circuit 19, an automatic shift control circuit 20, a lockup control circuit 21, a manual switching valve 26, and the like, and the hydraulic oil pumped up from the oil pan by the hydraulic pump 18 is line pressure controlled. It is supplied to the automatic shift control circuit 20 and the lockup control circuit 21 via the circuit 19. The line pressure control circuit 19 is provided with a hydraulic control valve (not shown) for controlling the line pressure for controlling the hydraulic pressure from the hydraulic pump 18 to a predetermined line pressure.
Are the clutches RC, HC, LC of the transmission gear mechanism 15.
And a plurality of shift hydraulic control valves (not shown) for controlling the hydraulic pressure supplied to the brakes B0 and B1.

Further, the lockup control circuit 21 is provided with a lockup control hydraulic control valve (not shown) for controlling the hydraulic pressure supplied to the lockup clutch 16. Further, between the line pressure control circuit 19 and the automatic shift control circuit 20, there is provided a manual switching valve 26 that is switched in conjunction with the operation of the shift lever 25. When the shift lever 25 is operated to the N range or the P range, even if the hydraulic control valve of the automatic shift control circuit 20 is deenergized (OFF), the manual switching valve 26 allows the shift gear mechanism 15 to operate. The hydraulic pressure supplied to the switch is switched so as to bring the transmission gear mechanism 15 into a neutral state.

On the other hand, the engine has a crankshaft 1
3 is provided with a crank rotation speed sensor 27 as an input side shaft rotation speed detecting means for detecting the rotation speed Ne (the input side shaft rotation speed of the torque converter 12), and the transmission gear mechanism 15 has a rotation speed of the turbine shaft 14. A turbine rotation speed sensor 28 as an output side shaft rotation speed detecting means for detecting Nt (output side shaft rotation speed of the torque converter 12) and a reduction rotation for detecting a rotation speed No of the reduction drive shaft 35 from the speed change gear mechanism 15. A speed sensor 29 is provided.

Output signals from these various sensors are output to an automatic transmission electronic control circuit (hereinafter referred to as "AT-ECU") 3
Input to 0. The AT-ECU 30 is mainly composed of a microcomputer. This AT-ECU
Reference numeral 30 denotes the speed change gear mechanism 1 according to a preset speed change pattern of FIG. 3 stored in a built-in ROM (storage medium).
In order to perform the shift of No. 5, the energization of each hydraulic control valve of the automatic shift control circuit 20 is controlled according to the operation position of the shift lever 25 and the operating conditions (throttle opening, vehicle speed, etc.).
Then, by energizing each hydraulic control valve, engagement / release of each clutch RC, HC, LC and each brake B0, B1 of the transmission gear mechanism 15 is switched, and a combination of gears for transmitting power is switched. Thus, the gear ratio of the transmission gear mechanism 15 is switched. In the following, the oil pressure to the clutch LC is the main clutch pressure, the oil pressure to the brake B1 is the hill hold pressure, the differential rotation speed between the input side and the output side of the torque converter 12, that is, the rotation speed Ne of the crankshaft 13 and the turbine shaft 14. The rotational speed difference from the rotational speed Nt will be referred to as the slip amount for the description.

In the automatic transmission constructed as described above, the pseudo neutral state is formed in this embodiment. The pseudo-neutral state has two purposes: to prevent a response delay that occurs when the clutch LC is re-engaged and to prevent the torque converter 12 from consuming torque, that is, to suppress deterioration of fuel consumption. The slip amount is controlled to a desired value. At this time, the desired slip amount is set to, for example, 100 rpm, thereby reducing the torque consumed by the torque converter 12 and suppressing the load on the engine from deteriorating the fuel consumption. The purpose is to prevent a response delay by controlling the piston stroke of the clutch LC to be small.

Now, the control in the pseudo neutral state will be described with reference to the time chart of FIG. 4 and the pseudo neutral control routine of FIG. Pseudo-neutral control is composed of three controls of predictive control, transient control, and steady control, and an outline of each of these three controls will be described. First, in step S100 of the flowchart of FIG. 5, it is determined whether or not the start condition of the prospective control is satisfied. The starting condition of the predictive control is that the brake signal is turned on by the driver depressing the brake as shown in FIG. 4A, and the signal from the throttle sensor not shown as shown in FIG. 4B. Is 0, and the vehicle speed is "0" rp as shown in FIG. 4 (c).
m, and so on.

When these conditions are satisfied, step S100 of FIG. 5 is affirmative (Yes), and step S100
Proceed to 200 and execute the prospective control. Probability control is
The control is executed from time T1 to time T2 in the time chart of FIG. 4, and FIG. 4 (f) shows the main clutch pressure for the clutch LC. The main clutch pressure is reduced by a predetermined pressure simultaneously with the start (time T1). Then, thereafter, the main clutch pressure is controlled to a pressure at which slip does not occur by gradually reducing the pressure sufficiently smaller than the predetermined pressure. The pressure at which slip does not occur is a value at which slip does not occur when the clutch LC is in the engaged state, and the predetermined pressure is a value set based on the average main clutch pressure at the time of stable control described later. is there.

The reason for controlling the main clutch in this way is that the vehicle speed is detected as "0" and the clutch LC is controlled in the engagement region where slip does not occur promptly. The oil pressure becomes unstable by suddenly reducing the pressure. For this reason, since the hydraulic pressure becomes unstable, in the present embodiment, as described above, the hydraulic pressure is gradually reduced after the predetermined pressure is reduced, and the engagement region is controlled to such an extent that slip does not occur.

The hill hold pressure shown in FIG. 4 (g) indicates the hydraulic pressure for the brake B1 at time T1.
At, the hydraulic pressure is increased so that the brake B1 changes from the released state to the engaged state. If the execution condition of the transient / steady state control is satisfied during the execution of such predictive control, step S of FIG.
The prospective control execution condition of 100 is denied (No), and the process proceeds to step S300. Then, in step S300, the transition / steady state control start condition is already satisfied, so the determination here is affirmative (Yes), and step S300 is performed.
In step 400, the transient / steady state control is executed.

The condition for executing the transient / steady state control is the clutch L.
In the engagement state of C, in the engagement region where slip does not occur, the condition that the hydraulic pressure supply by the automatic transmission circuit 20 is stable is desirable. For example, the satisfaction of the condition is set in advance by adaptation or the like. You may set a predetermined period. This transient / steady-state control shows a characteristic part of the present invention. Here, only the outline of the transient / steady state control will be described, and the detailed description of the present invention will be given later.

As described above, the purpose of the pseudo neutral control is to set the slip amount to, for example, 100 rpm to reduce the load on the engine to improve fuel consumption and to set the piston stroke of the clutch LC to zero. It is intended to suppress a response delay at the time of re-engagement. In order to achieve these two purposes, the control area of the engagement state of the clutch C0 is controlled to an extremely narrow control area. Therefore, in order to control the clutch LC to this target engagement region, transient / steady control is started at time T2. When this transient / steady state control is started, the target slip amount is set by a different setting method depending on the degree of progress of the control. Then, feedback control of the main clutch pressure in FIG. 4 (f) is performed based on the deviation between the target slip amount and the actual slip amount to achieve both responsiveness and stability, and control the engagement state of the clutch LC with high accuracy. be able to. When the target engagement state reaches the engagement state of the clutch LC, at time T3,
Steady state control is executed to maintain this engaged state. In addition,
As described above, by learning the average main clutch pressure during the steady control performed after time T3 in FIG. 4, the main clutch pressure is set to the extent that slip does not occur during the prospective control.

As described above, the slip amount is 100 rp
The torque converter 12 is controlled by controlling the torque to be m.
It is possible to reduce the torque consumed in step S1 and control the pseudo neutral state in consideration of the response delay at the time of re-engagement. By the way, when the driver depresses the accelerator pedal to shift from the driving state to the traveling mode from the driving state, the re-engagement start condition of step S500 of FIG.
0 is negated (No). Since the determination in step S400 is affirmative (Yes), step S60
At 0, the main clutch pressure is increased to engage the clutch LC and re-engagement control is executed. At this time, step S
All determinations of 100, S300 and S500 are negative (No)
If so, the processing of the pseudo-neutral control routine is terminated without executing as it is.

The present embodiment is characterized by the transient / steady state control, and in controlling the engagement area of the clutch LC to the target engagement area, the clutch L achieves both stability and responsiveness.
The purpose is to transfer C to the target engagement area. In the following, the transient / steady state control of the present embodiment will be described with reference to FIGS.
This will be described in detail with reference to the flowchart of. First, FIG.
The flowchart of FIG.
This program is started when the steady control start condition is satisfied, and thereafter is started every predetermined period in synchronization with the rotation of a crank shaft (not shown) of the engine.

The transient / steady state control start condition of step S300 of FIG. 5 is set to, for example, 2 seconds as a predetermined period from time T1 of the time chart of FIG.
The start condition is satisfied when 2 seconds have elapsed after the prospective control was started. This predetermined period is a period set for the following reason. First, the main clutch pressure is reduced by a predetermined pressure at the start of the prospective control, so that the main clutch pressure becomes unstable. After that, the pressure is gradually reduced, but the main clutch pressure stabilizes in about 2 seconds after the start of the prospective control.

When the transient / steady state control start condition is satisfied, the flowchart of FIG. 6 is started. In this program, depending on the progress of control, Sty_1 to Sty_4
Execute control. In each control, the method of setting the target slip amount is performed by different methods. First, in step S410, it is determined whether the slip amount has changed. At the start of transient / steady control, the vehicle speed is 0 rpm,
The reduction rotation speed No is also 0 rpm. Therefore, when the transient / steady control is started, the clutch LC
Are engaged and the turbine rotation speed Nt is zero. In step S410, it is determined whether the slip amount changes from this state. The slip amount is the crank rotation speed N.
Since it is the difference rotation speed between e and the turbine rotation speed Nt,
It may be determined whether or not the turbine rotation speed Nt has changed.

In step S410, if the slip amount or the turbine rotation speed Nt has not changed,
In step S420, it is determined whether CTM1 has passed for a predetermined period. The predetermined period CTM1 is a guard value set for shifting to the process of step S430 even if the turbine rotation speed Nt does not change. If the predetermined period CTM1 has not elapsed, step S
Proceeding to 430, the Sty_1 control is executed and this routine is ended.

The Sty_1 control will be described in detail with reference to the flowchart shown in FIG. This flowchart is a subroutine that is activated each time the process of step S430 in FIG. 6 is called. First, step S43
At 1, it is determined whether the initial setting is completed. Here, the initial setting is the setting process shown in steps S432 to S434, in which the initial target slip amount tgSL at which this routine is started is set, and the control gain P · I · D during the execution of the Sty_1 control is set. This indicates setting and resetting a flag Ft described later.

First, in step S432, the current actual slip amount SL is set as the target slip amount tgSL, and the flow proceeds to step S433. In step S433, the control gain P.I.
As D, P1, I1, and D1 are set, respectively. Since these three control gains are controls during execution of the Sty_1 control, high gains are set in consideration of responsiveness.
Then, a flag Ft, which will be described later, is set to 0 and the present routine is ended. On the other hand, if it is determined in step S431 that the initial setting is completed, the process proceeds to step S435.
In step S435, a value obtained by subtracting a predetermined value CSL from the last tgSL is set as the target slip amount tgSL. It should be noted that this predetermined value CSL is a value that is appropriately set due to compatibility or the like. As described above, when the transient / steady state control routine is started, the Sty_1 control is executed.
In this control, the target slip amount is gradually set to a small value, and a high feedback gain P.I.D. is set with emphasis on responsiveness.

Again referring to the flow chart of FIG.
The steady control will be described. Step S41 described above
When the determination of 0 is negative (No) or the determination of step S420 is affirmative (Yes), the process proceeds to step S440. That is, if either the turbine rotation speed Nt or the slip amount has changed, or if the predetermined period CTM1 has elapsed, then either step S44 is performed.
Go to 0. In step S440, it is determined whether or not a predetermined period CTM2 has passed since the end of Sty_1 control. Although this predetermined period CTM2 will be described later, it is a value set in the processing of the Sty_2 control shown in step S450. In the determination of step S440, if this determination is the first time, it is forcibly determined that the predetermined period CTM2 has not elapsed, the process proceeds to step S450, and Sty_
2 Execute control. In this step, the subroutine shown in FIG. 8 is called and executed.

First, when the Sys_2 control routine of FIG. 8 is started, the flag Ft = 1 in step S451.
Is determined. If the activation of this flowchart is the first time, step S4 of the flowchart of FIG.
Since the flag Ft is set to 0 in the process of S34, the determination in step S451 of FIG. 8 is negative (No), and the process proceeds to steps S452 to S453. In steps S452 and S453, the target slip amount tgSL and the predetermined period CTM2 are calculated.
The target slip amount tgSL and the predetermined period CTM2 are calculated by using a quadratic function as the target slip amount CSL from the current actual slip amount to the final target slip amount CSL of the pseudo neutral control, for example, at each time point until reaching 100 rpm. The slip amount tgSL and CTM2 for a predetermined period until reaching 100 rpm are obtained.

Specifically, the target slip amount tgSL is defined by the following quadratic function.

Target slip amount tgSL = a (t−b) ² + c (1) In this equation, the constant a is a value determined by the adaptation, etc., and reaches the final target slip amount from the current slip amount. Determine the curvature of the curve up to. That is, the larger the constant a, the steeper the final target slip amount, and the smaller the constant a, the gentler the target slip amount. The constant c corresponds to the final target slip amount CSL,
The constant b corresponds to CTM2 for a predetermined period.

Therefore, the target slip amount tgSL and the predetermined period CTM2 can be obtained from the following two relations. One is the current slip amount, which is (t, tgS
L) = (0, current actual slip amount SL). And, as the second, (t, tgSL) = (CTM for a predetermined period)
2, the final target slip amount CSL). The target slip amount tgSL and the predetermined period CTM2 can be determined by substituting these two relationships into the equation (1).

As described above, the target slip amount tgS
When L and CTM2 are set for a predetermined period, step S45
4 and gain P2 for control gains P, I, D respectively
-I2 and D2 are set, and the process proceeds to step S455. In step S455, steps S452 to S452
A flag Ft indicating that the calculation of 454 is completed is set to 1 and the process proceeds to step S456. In step S456, the current slip amount SL is set to the target slip amount tgSL, and this routine ends.

On the other hand, flag Ft = 1 in step S451.
, That is, steps S452 to S452
If the processing of 456 has ended, step S45.
The determination of 1 is affirmative (Yes), and the process proceeds to step S457. In step S457, the target slip amount tgSL is calculated by substituting the elapsed time after the end of the Sty_1 control into the equation (1). As described above, until the predetermined period CTM2 elapses, the present Sty_2
The target slip amount tgSL is calculated by the control.

On the other hand, step S in the flowchart of FIG.
When it is determined at 440 that the CTM2 has passed the predetermined period, the process proceeds to step S460. In step S460,
It is determined whether or not a predetermined period CTM3 has elapsed since the end of the Sty_2 control. Here, if it is determined that the CTM3 has not elapsed for the predetermined period, the process proceeds to step S470 and S
ty_3 control is executed. In this process, the subroutine shown in FIG. 9 is called as the Sty_3 control. Next, the Sty_3 control will be described with reference to the flowchart of FIG.

When the present control is executed, the actual slip amount SL approaches the final target slip amount CSL, so the final target slip amount CSL is set as the target slip amount tgSL, and the response as the control gain is responsiveness. Set a large control gain with emphasis on. Specifically, in step S471, the target slip amount tgSL is set to the final target slip amount CSL, and the process proceeds to step S472. In step S472, the gains P3, I3, D3 are set as the control gains P, I, D, respectively, and this routine is ended.

Next, a case where the predetermined period CTM3 has elapsed since the end of the Sty_3 control will be described. In this case, the determination in step S460 of the flowchart in FIG. 6 is affirmative (Yes), and the process proceeds to step S480. In the process of step S480, the subroutine of FIG. 10 is called to execute the Sty_4 control. In this control, the actual slip amount SL is the final target slip amount CSL.
Therefore, the final target slip amount CSL is set as the target slip amount tgSL, and the control gain is set to a small control gain with emphasis on stability.
Specifically, in step S481, the target slip amount t
gSL is set to the final target slip amount CSL, and the process proceeds to step S482. In step S482, the gains P3, I3, D3 are set as the control gains P, I, D, respectively, and this routine is ended.

As described above, in the present embodiment, by setting the target slip amount tgSL according to the degree of progress of control as the transient / steady state control, responsiveness and stability can be achieved in a very narrow control region. It is possible to control the clutch LC with high accuracy for the purpose of improving the property.

Next, the control of the main clutch pressure for the clutch LC will be described with reference to the flowchart of FIG. This flowchart is a general feedback control that has been known in the past. This flowchart is a program that is started in synchronization with a predetermined rotation of a crank shaft (not shown) of the engine. When this program is started, first, in step S701, the target slip amount tgSL is called. Then, the actual slip amount is called and the process proceeds to step S703. Step S703
Then, the control gain P · I set in FIGS.
-Call D and proceed to step S704.

In step S704, step S701
The main clutch pressure Pcl (n) is calculated based on the respective values called in step S703. The main clutch pressure Pcl (n) is represented by the following mathematical formula.

Pcl (n) = initial value + P × (tgSL−SL) + I × Σ (tgSL−SL) + D × d / dt (tgSL−tgSL) (2) In the above equation, the target slip amount is tgSL, The actual slip amount corresponds to SL. Further, the actual slip amount at time T2 in FIG. 4 is set as the initial value. Feedback control is performed according to the deviation between the target slip amount and the actual slip amount, and this routine ends. As mentioned above,
By setting the target slip amount and the control gain in the present embodiment, in the transient / steady state control, the target slip amount is set by a different target slip amount setting method depending on the control progress state, and the control progress Since the control gain is set according to the state, the optimum main clutch pressure control can be executed based on the deviation between the target slip amount and the actual slip amount. Therefore, it is possible to accurately control the clutch LC to the engagement state in which the final target slip amount is achieved while achieving both responsiveness and stability.

The transient / steady state control of this embodiment will be described with reference to the time charts of FIGS. 13 to 18. First, in the time chart of FIG.
When the execution condition of the steady control is satisfied, S is executed at time t1 in the figure.
The ty_1 control is executed. In this Sty_1 control,
The target slip amount is gradually changed as shown by the dotted line, and the control gain is set to a high gain with emphasis on responsiveness. Then, due to the change of the actual slip amount SL or the elapse of the predetermined period CTM1, Sty_2 at time t2 in the figure.
The control execution conditions are met. In the Sty_2 control, first, the target slip amount tgSL is set to the current actual slip amount SL. Then, the target slip amount t thereafter
gSL is obtained by a quadratic function. At this time, the target slip amount tg is represented by showing the current actual slip amount SL to the final target slip amount CSL as a quadratic function.
A predetermined period CTM2 until SL reaches the final target slip amount CSL is obtained. Then, during the execution of the Sty_2 control, the time at the time of calculation is input to the above-described quadratic function to obtain the target slip amount tgSL, the target slip amount tgSL at the time of calculation is obtained, and the control gain that emphasizes stability is set. It is set. The method of calculating the target slip amount is not limited to the quadratic function, but N
It may be calculated by the following function.

When the predetermined period CTM2 ends, the execution condition of the Sty_3 control is satisfied at time t3 in the figure. The target slip amount tgSL is the final target slip amount CSL.
Fixed to. The control gain at this time is set to a high control gain so as to quickly follow the final target slip amount CSL. Then, at time t4, Sty_4
Control is executed. In this control, the target slip amount tgSL is set to the final target slip amount CSL as in the Sty_3 control. Further, the control gain is set to a low gain in consideration of stability.

As described above, in the transient / steady state control of the present embodiment, the target slip amount tg is changed according to the control progress state.
By changing the setting method of SL and switching and setting the control gain, both the responsiveness and the stability can be achieved, and the actual slip amount SL can quickly follow the final target slip amount CSL. it can. That is, as for the engaged state of the clutch LC, it is possible to control both the responsiveness and the stability in an extremely narrow control region with high accuracy.

In the present embodiment, Sty_1
In the control, the target slip amount tgSL is set to be gradually smaller, but as shown in FIG. 14, the execution condition of the Sty_1 control is satisfied, the target slip amount is subtracted by a predetermined value, and then the target slip amount tgSL is fixed to that value. You may.

In addition, with respect to the method of calculating the target slip amount tgSL in the above-described Sty_1 control, FIG.
In the time charts shown in FIGS. 16A and 16B, the target slip amount tgSL in the Sty_2 control is set by a linear function (straight line).

Further, as shown in the time charts of FIGS. 17 and 18, instead of the method of calculating the target slip amount tgSL in the above-mentioned Sty_2 control, in the method of calculating the target slip amount tgSL in the Sty_1 control, a smaller predetermined value is used. The target slip amount tgSL may be subtracted by the value.

By the way, in the present embodiment, Sty_2
As the calculation of the target slip amount tgSL in the control, the CTM2 was determined at the same time for the predetermined period. Target slip amount tgS
L was set so as to follow the final target slip amount CSL during this predetermined period CTM2, but instead of this,
Even if the target slip amount tgSL is set so as to follow the final target slip amount CSL during the set period by setting a period smaller than the predetermined period CTM2 obtained when the target slip amount tgSL is calculated by the quadratic function. good.

In the present embodiment, as described above, the transient / steady control is divided into four control sections, and a target slip amount calculation method and a control gain setting method which are different in each section are proposed. However, the present embodiment is not limited to the division into four control sections, and the control section division and the control gain may be set in consideration of control accuracy, cost, and the like.

In this embodiment, the fluid transmission mechanism is the lockup clutch 12, the forward clutch is the clutch LC, the input side shaft rotation speed detecting means is the crank rotation speed sensor 27, and the output side shaft rotation speed detecting means is. The turbine rotation speed sensor 28, the differential rotation speed calculation means corresponds to the means for calculating the slip amount, the hydraulic control means corresponds to the flowcharts of FIGS. 7 to 11, and the target differential rotation speed changing means corresponds to the flowchart of FIG. ,Function.

<Second Embodiment> In the first embodiment, the target slip amount tgSL is set by the calculation method using the Nth-order function as the Sty_2 control. However, in the present embodiment, a different method is used. Then, the target slip amount tgSL in the Sty_2 control is calculated.

This will be described in detail with reference to the flowchart of FIG. The flowchart of FIG. 12 is a program that is started each time the process of step S450 of the transient / steady state control routine of the first embodiment is executed. When this program is started, in step SX451, the gains P5, I6, and
Set D6. This gain has a small value in consideration of stability. Then, in step SX452,
It is determined whether the target slip amount tgSL is equal to or less than the actual slip amount SL. That is, when the actual slip amount SL is larger than the target slip amount tgSL, the determination in step SX452 is negative (No), and step SX is executed.
Proceeding to 454, the previous target slip amount tgSL is set as the current target slip amount tgSL.

On the other hand, the actual slip amount SL is the same value as the target slip amount tgSL, or the target slip amount tgSL
When the value becomes smaller than the above, step SX45
The determination of 2 is affirmative (Yes), and the process proceeds to step S453. In the process of step S453, the predetermined slip amount CSL2 is subtracted from the previous target slip amount tgSL and set as the current target slip amount tgSL. That is, the calculation method of the target slip amount tgSL in the present embodiment is set so that it is always smaller than the value of the actual slip amount SL. At this time, the predetermined slip amount tgSL indicates that the change in the main clutch pressure depends on the clutch LC.
It is desirable to set it in a range that does not greatly affect the engagement state (driving torque). As a result, the clutch LC
Since a large change in the engagement state of the clutch LC is suppressed, it is possible to control the engagement state of the clutch LC with high accuracy while achieving both responsiveness and stability.

Next, the control of this embodiment described above will be described with reference to the time charts shown in FIGS. 19 and 20. 19 and 20, the target slip amount tgSL in the Sty_1 control described in the first embodiment is shown.
The setting method of is different. Since this has been described in the first embodiment, detailed description will be omitted. In the Sty_2 control of the present embodiment, the target slip amount tgSL
The actual slip amount is the target slip amount tg
When it becomes equal to or less than SL, the predetermined slip amount CSL2 set within a range that does not significantly affect the engagement state (driving torque) of the clutch LC is set to the previous target slip amount t.
By subtracting from gSL, the target slip amount tgS of this time
Calculate L. As a result, the target slip amount tg is always
SL is set to a value smaller than the actual slip amount SL.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is a schematic view showing an automatic transmission mechanism of the present invention.

FIG. 3 is a map showing a shift pattern of the present invention.

FIG. 4 is a time chart showing general pseudo-neutral control.

FIG. 5 is a main program of the pseudo neutral control of the present invention.

FIG. 6 is a flowchart showing the transient / steady state control of the present invention.

FIG. 7 is a program showing Sty_1 control in the first embodiment.

FIG. 8 is a program showing Sty_2 control in the first embodiment.

FIG. 9 is a program showing Sty_3 control in the first embodiment.

FIG. 10 is a program showing Sty_4 control in the first embodiment.

FIG. 11 is a program showing feedback control of main clutch pressure in the present invention.

FIG. 12 is a program showing Sty_2 control in the second embodiment.

FIG. 13 is a time chart showing the transient / steady state control in the first embodiment.

FIG. 14 is a time chart showing the transient / steady state control in the first embodiment.

FIG. 15 is a time chart showing transient / steady-state control in the first embodiment.

FIG. 16 is a time chart showing the transient / steady state control in the first embodiment.

FIG. 17 is a time chart showing the transient / steady state control in the first embodiment.

FIG. 18 is a time chart showing the transient / steady state control in the first embodiment.

FIG. 19 is a time chart showing the transient / steady state control in the second embodiment.

FIG. 20 is a time chart showing transient / steady-state control in the second embodiment.

[Explanation of symbols]

11 ... Automatic transmission, 12 ... Torque converter, 16 ... Lockup clutch, 17 ... Hydraulic control circuit, 18 ... hydraulic pump, 19 ... Line pressure control circuit, 20 ... Automatic shift control circuit, 21 ... Lockup control circuit, 26 ... Manual switching valve, 27 ... Engine speed sensor, 30 ... AT-ECU, LC, HC, RC ... Clutch (friction engagement element), B0, B1 ... Brake (friction engagement element).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16H 59:44 F16H 59:44 F term (reference) 3J552 MA02 MA12 NA01 NB01 PA20 PA47 PA54 QA13C RA27 RB03 SA03 SA07 SA56 TA02 VA07W VA32W VA42W VA42Y VA45Z VA53Z VA62Z VA66W VA76W VB01W VC01W VC03Z VD11Z

Claims (8)

[Claims] 1. A control device for an automatic transmission that forms a pseudo-neutral state when a forward drive range is selected, the vehicle is in a stopped state, and the engine is in an idle operation state. A fluid transmission mechanism for transmitting to the device, a forward clutch that is engaged when a forward travel range is selected, a hydraulic control valve for engaging the forward clutch by supplying hydraulic pressure, and the fluid transmission mechanism Input side shaft rotation speed detecting means for detecting the input side shaft rotation speed of the, the output side shaft rotation speed detecting means for detecting the output side shaft rotation speed of the fluid transmission mechanism, and by adjusting the hydraulic control valve, The hydraulic pressure control means for controlling the hydraulic pressure supplied to the forward clutch, and the signals detected by the input side shaft rotation speed detection means and the output side shaft rotation speed detection means Differential rotational speed calculation means for calculating a difference, target differential rotational speed setting means for setting a target differential rotational speed between the input side shaft rotational speed of the fluid transmission mechanism and the output side shaft rotational speed of the fluid transmission mechanism, In the period in which the vehicle is in the stopped state and the engine is in the idle operation state and then transitions to the pseudo neutral state, the target differential rotation speed setting means,
The target differential rotation speed changing means for changing the setting method of the target differential rotation speed according to the progress state of the period, the hydraulic pressure control means, the target differential rotation speed setting means by the target difference rotation speed changing means. The hydraulic pressure supplied to the forward clutch is controlled based on the target differential rotational speed set based on the changed target differential rotational speed setting method and the actual differential rotational speed calculated by the differential rotational speed calculation means. A control device for an automatic transmission, characterized in that 2. The hydraulic pressure control means for forward movement is based on a deviation between a target difference rotation speed set by the target difference rotation speed setting means and an actual difference rotation speed calculated by the difference rotation speed calculation means. The automatic transmission according to claim 1, further comprising feedback gain changing means for changing a control gain of the feedback control according to a progress state of the period, which is a means for feedback controlling the hydraulic pressure supplied to the clutch. Control device. 3. The target differential rotation speed changing means divides the period into a plurality of sections, and calculates the target rotation speed by a different setting method in each section. A control device for an automatic transmission according to any one of 1. 4. The target differential rotation speed changing means sets the target differential rotation speed by a predetermined function in at least one section of the periods divided by the plurality of sections. The control device for the automatic transmission according to item 3. 5. The control device for an automatic transmission according to claim 4, wherein the predetermined function is a quadratic function. 6. The actual differential rotation speed calculated by the differential rotation speed calculation means in at least one section of the periods divided by the plurality of sections is the target differential rotation speed changing means. When it becomes less than or equal to the target differential rotation speed set by the target differential rotation speed changing means, the hydraulic pressure applied to the forward movement clutch does not change significantly from the previous target differential rotation speed, and the forward movement speed is set early. The automatic differential motor according to any one of claims 3 to 5, wherein the target differential rotational speed at this time is set by subtracting a predetermined differential rotational speed set within a range in which the engagement of the clutch progresses. Transmission control device. 7. A controller for an automatic transmission that forms a pseudo-neutral state when a forward drive range is selected, the vehicle is at a standstill and the engine is in an idle state, and the rotation of the engine is fluidized. A fluid transmission mechanism for transmitting to the transmission through the forward gear, a forward clutch that is engaged when the forward drive range is selected, a hydraulic control valve for engaging the forward clutch by supplying hydraulic pressure, Input side shaft rotation speed detecting means for detecting an input side shaft rotation speed of the fluid transmission mechanism, output shaft side rotation speed detecting means for detecting an output side shaft rotation speed of the fluid transmission mechanism, and the hydraulic control valve is adjusted. To control the hydraulic pressure to be supplied to the forward clutch, and the input side shaft rotation speed detection means and the output shaft side rotation speed detection means. Differential rotation speed calculation means for calculating the deviation between the respective signals, and a target differential rotation speed setting for setting a target differential rotation speed between the input side shaft rotation speed of the fluid transmission mechanism and the output side shaft rotation speed of the fluid transmission mechanism. And a means for dividing the period into first to fourth periods in a period in which the vehicle is stopped and the engine is in an idle operation state and then transitions to the pseudo-neutral state. The differential rotation speed setting means is the first
The target differential rotation speed is gradually reduced in the period of, the target differential rotation speed is set by a function of a plurality of orders in the second period, and in the third period and the fourth period,
Means for setting the target differential rotation speed to the final target differential rotation speed in the pseudo-neutral state, wherein the hydraulic pressure control means calculates the target differential rotation speed changed by the target differential rotation speed changing means and the differential rotation speed calculation. A control device for an automatic transmission, characterized in that the hydraulic pressure supplied to the forward clutch is controlled based on the actual rotational speed difference calculated by the means. 8. The hydraulic pressure control means for the forward movement is based on a deviation between a target differential rotation speed set by the target differential rotation speed setting means and an actual differential rotation speed calculated by the differential rotation speed calculation means. It is a means for feedback controlling the hydraulic pressure supplied to the clutch, and is a control gain of the feedback control set in the second and fourth periods with emphasis on responsiveness in the first and third periods. A gain higher than that of the feedback control is set in the periods of the second and fourth, and stability is emphasized, and a gain lower than the control gain of the feedback control set in the periods of the first and third is set. The control device for an automatic transmission according to claim 7, wherein: