JPS6367461A - Lock-up control device for automatic transmission - Google Patents

Abstract

PURPOSE:To mitigate shocks by detecting the inertia phase during speed change in a lock-up region and slip-controlling a torque converter in the inertia phase so that the slip quantity becomes a value between zero and the maximum. CONSTITUTION:An automatic transmission 2 is allowed to a transfer the power smoothly with the torque fluctuation absorbing function and torque increasing function of a torque converter 1 provided on a power transfer system. The inertia phase is detected by an inertia detection means 3 while the automatic transmission 2 is performing the speed change in a lock-up region. A torque converter 1 is slip-controlled by a slip control means 4 in this inertia phase so that the slip quantity becomes a value between zero and the maximum, i.e., between the lock-up state and converter state. Accordingly, the lock-up stat is not changed to the converter state at a stretch, and the change width of the transfer state is small, thus shocks are mitigated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a lock-absorption control device during gear shifting of an automatic transmission.

(Prior Art) An automatic transmission includes a torque converter in its power transmission system, and its torque increasing function and torque fluctuation absorbing function enable smooth power transmission.

By the way, since a torque converter is a transmission means using fluid, relative rotation (slip) between input and output elements cannot be avoided, which deteriorates transmission efficiency.

Therefore, in high vehicle speed ranges where the torque fluctuation absorbing function and torque increasing function described above are unnecessary, automatic transmissions in which the input and output elements of the torque converter are directly coupled (locked up) to eliminate slip are being used frequently.

However, if the torque converter is left in the lock amplifier state during a shift in the lock-up region where the amount of slip should be reduced to zero, a large shift shock will occur.

In order to prevent this, a technique has been proposed in Japanese Patent Laid-Open No. 127856/1983 that keeps the torque converter in a converter state in which slip is not restricted even in the frontage pull-up range for a predetermined period of time required for shifting based on the shifting command.

(Problem to be Solved by the Invention) However, in this lock-up control technology, since the torque converter is switched from the lock-up state to the converter state all at once, it is not possible to prevent shocks from occurring due to sudden changes in the transmission state, and it also cannot control the speed change. When the shift timing shifts due to a change in hydraulic pressure, this does not match the timing of the torque converter's state switching, resulting in peak torque and engine racing, which also causes shock.

(Means for Solving the Problems) From the viewpoint that these problems occur during the inertia phase during gear shifting and because the torque converter is brought into the converter state from the lock amplifier state all at once, the present invention provides the first aspect of the present invention. As conceptually shown in the figure, an automatic transmission 2 includes a torque converter 1 in its power transmission system and can appropriately limit the amount of slip between its input and output elements.
Assuming that, there is an inertia phase detection means 3 that detects the inertia phase during gear shifting in the lock amplifier region, and a slip control that controls the torque converter to slip in this inertia phase so that the amount of slip is between zero and maximum. Means 4 is provided.

(Function) The automatic transmission 2 uses a torque converter 1 installed in the power transmission system.
Smooth power transmission is possible with the torque fluctuation absorbing function and torque increasing function.

While the automatic transmission 2 is shifting in the lock amplifier region, the means 3 detects the inertia phase during the shifting. In this inertia phase, the means 4 performs slip control on the torque converter 1 so that the amount of slip is between zero and the maximum value, that is, between the lock-up state and the converter state.

Therefore, in the inertia phase, the torque converter l
The converter state does not change from the lock-up state to the converter state all at once, and the range of change in the transmission state is small, making it possible to reduce the shock caused by this change. In addition, even if the shift timing is shifted due to changes in the oil pressure that governs gear shifting, the above-mentioned slip control is performed in the inertia phase, so the gear shifting will always be performed during slip control, and the gear shifting will be performed by slip control of the torque converter. It is possible to suppress peak torque and engine revving, and the shock that comes with these can also be reduced.

(Example) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 2 shows an embodiment of the device of the present invention, in which 10 is an engine, 1
1 is a torque converter, and 12 is a gear transmission mechanism. The torque converter 11 and the gear transmission mechanism 12 constitute a power transmission system of an automatic transmission. Power from the engine 10 is supplied from the crankshaft 3 to the pump impeller (input element) 11a of the torque converter 11, and the pump impeller lla passes through the internal working fluid to the turbine runner (
Output element) 11b is fluid-driven to convert torque converter 1
1 to transmit power from the crankshaft 13 to the transmission input shaft 14. The gear transmission mechanism 12 increases or decreases the power from the input shaft 14 according to the selected gear ratio, and transfers the power from the input shaft 14 to the transmission output shaft 15.
Furthermore, the selected gear ratio can be automatically changed by a hydraulic circuit (not shown) to perform speed changes.

Note that the torque converter 11 has a spline l on the shaft 14.
When equipped with a lock-up clutch lid connected by lc and moved to the left in the figure and directly connected to the shaft 13 via the clutch facing lie, input/output elements 11a and Ilb
The amount of slip between the lid and the lid shall be limited.
The bonding force (slip amount) is the application pressure P into the chamber 11f.
It can be controlled by the differential pressure between A and the release pressure PR into the chamber 11g.

In order to control these pressures pA, p, the line pressure (P
, ) Two pressure reducing valves 17 and 18 are connected to the circuit 16, and the circuit 16 regulates the pressure of oil from the oil pump 19 by a regulator valve (not shown), so that the line pressure P
It is kept at L. The pressure reducing valve 17 lowers the line pressure PL by a spring 17a.
It is assumed that the pressure is reduced to a constant value corresponding to the spring force and output to the circuit 20, and a constant apply pressure PA is continuously supplied from the circuit 20 to the chamber 11f.

Further, the pressure reducing valve 18 is assumed to reduce the line pressure Pt to a constant value corresponding to the spring force of the spring 18a, and output a constant pilot pressure PP to the circuit 21.

A hydraulic actuator 22 and a release pressure regulating valve 23 are connected to the circuit 21 . The actuator 22 includes a spool 22b and a plunger 22c on both sides of a diaphragm 22a in a coaxial abutting relationship.
2b is brought into contact with the diaphragm 22a by a spring 22d with an extremely small spring force (the plunger 22c is biased to the left in the figure by the electromagnetic force that increases as the current i to the solenoid 22e increases, and the spool 22b is The spool 22b connects the output port 22f to the input port 22g by moving to the left, and connects the output port 22f to the drain boat 22h by moving to the right. Pressure P
P and output pressure P0 from the output port 22f to the chamber 2.
By feeding back to 2i, the actuator 22
For example, the output pressure P0 is changed to the third output pressure by the solenoid drive current i.
It can be controlled as shown in the figure.

The release pressure regulating valve 23 is connected to the spool 23 by the spring 23a.
b is biased downward in the figure, and the pressure of the chambers 23c and 23d is applied to the spool 23b so as to oppose this spring. Actuator output pressure P is in the chamber 23c.

A circuit 24 is supplied from the output port 23e to the chamber 23d.
The release pressure PR toward the torque converter release chamber 11g is fed back through the . Then, by supplying the pilot pressure P to the input port 23f, the release pressure regulating valve 23 adjusts the release pressure PR to a value corresponding to the spring force of the spring 23a and the actuator output pressure P0 using this pilot pressure P as the source pressure. Adjust the pressure. By the way, spring 2
Since the spring force of 3a is constant, the release pressure P is the actuator output pressure P. becomes variable, and this output pressure P0
For example, it can be controlled as shown in FIG. 4 depending on the situation.

Solenoid (22) that determines the actuator output pressure P0
e) The drive current i is controlled by a microcomputer 25, which detects signals from oil pressure sensors 26 and 27 that detect the apply pressure PA and release pressure P, respectively, and the intake negative pressure V of the engine 10. Signals from the negative pressure sensor 28, engine rotational speed N, turbine (llb) rotational speed NT, and transmission output rotational speed N. Signals from rotation sensors 29 to 31 that respectively detect the rotation speed are input.

Based on this input information, the microcomputer 25
The control program shown in the figure is executed to determine the solenoid drive current i.

The control program in FIG. 5 is a regular interrupt routine that is repeatedly executed, for example, every 5 m5ec.
At this point, it is checked whether the first shift flag 5FLGI is set to 1 or not. This flag 5FLG
I is set to 1 when there is a shift command in the lock-up region by a shift control program (not shown), and when the shift is completed, it is reset to O as described later in the control program of FIG. 1 while shifting at
shall be maintained.

If the shift is not in the lock-up region (SFLG 1)
=O) Control is ended as is, and lockup control, which is the object of the present invention, is not executed.

During the shift in the lock-up region, step 40 selects step 41, where it is determined whether or not the shift is completed based on whether the transmission input/output rotation ratio Nt/No has reached the post-shift gear ratio λ. If the shift is not completed, it is checked in step 42 whether or not the second shift flag 5FLG■ is set to 1.As will be described later, this flag 5FLG■ is set to 1 when the inertia phase is entered during the shift, and when the shift is completed. It is assumed that it is reset to O and remains at 1 during the inertia phase. If the inertia phase is not in progress, in step 43, it is determined whether the inertia phase has started based on whether the transmission input/output rotation ratio NY/NO has begun to deviate from the gear ratio λ2 before the shift.

While the inertia phase has not yet started, steps 44 and 45 are skipped and the control proceeds from step 43 to step 46. In this step, the optimal friction element (without causing a shift shock and without causing a shift shock) is determined. In the next step 47, this operating pressure is commanded to the corresponding friction element to proceed with the gear shift.

When it is determined in step 43 that the inertia phase has started, the lock amplifier flag LFLG and the second shift flag 5FLG are set to 1 in steps 44 and 45, respectively. It is assumed that the lock-up flag LFLG is set to 1 during the inertia phase in which the lock-up control aimed at by the present invention is to be performed. Note that by executing step 45, step 42 will be changed from step 43 to step 45.
Step 45 is skipped and step 46 is selected.

In step 48, it is checked whether LFLG=1 or not to determine whether lockup control, which is the object of the present invention, should be executed. If the lock-up control is to be executed, the subroutine shown in FIG. 6 is executed in step 49 to calculate the required engagement capacity of the lock-up clutch lid corresponding to the engine torque, that is, the required release pressure P*(N). do.

In step 60 in FIG. 6, the engine rotation speed N.

The engine torque TE is determined by looking up the table data of and the suction negative pressure Vl. In the next step 61, the apply pressure PA is read, but this takes into account fluctuations in the apply pressure PA, and since the apply pressure PA is actually constant, the reading may be omitted. In the next step 62, the required engagement capacity of the lock amplifier clutch llb corresponding to the engine torque TE, that is, the required release pressure pH (N) corresponding to the engine torque T, is calculated as follows. That is, as shown in Fig. 2, the outer diameter of the clutch facing lie is expressed as D2, the inner diameter as D2, the average effective radius as r, and the actual inner diameter of the lock amplifier clutch lid as D.
3 and the friction coefficient of the clutch facing lie is μ, the required engagement capacity of the lock-up clutch is expressed by the following equation.

Tt = μX (AIXPA −Az X PR(N)
) Xr From the above equation, the required release pressure PI (N) for the engine torque TE is a number, so if these are set to It can be obtained by calculating K2X TE.

In the next step 50 in FIG. 5, the subroutine shown in FIG. 7 is executed to calculate the target release pressure PR(M). First, in step 70 of FIG. 7, a target slip amount is determined from the elapsed time of the inertia phase based on the data regarding the target slip amount of the torque converter shown in FIG.

The data in FIG. 8 is based on the speed change progress control in steps 46 and 47 in FIG. This is established to prevent peak torque and engine racing even when the timing is off. Actual slip ff1NEN in next step 71
T is calculated, and the deviation e between this and the target slip amount is calculated in step 72. In the next step 73,
Based on the slip amount deviation e, <PID calculation is performed to determine the release pressure correction amount to obtain the target slip amount. In other words, the release pressure correction amount PP due to proportional control is obtained by multiplying the proportional constant by the slip amount deviation e, and is calculated as Pp=KPxe, and the release pressure correction amount P+ due to integral control is determined by the integral constant K.
.

The current value multiplied by the slip amount deviation e and the previous correction amount P,
(OLD) and P+ = PI(OLD)
+ K + × e, and the release pressure correction book P0 by differential control is PI, which is obtained by multiplying the amount of change in slip amount deviation from the previous value e (OLD) to the current value e (NEW) by the differential constant.

= Ko (e(OLD) e(NEW)). Then, in the next step 74, the above PID
Add up the calculation results and get the final release pressure correction amount PF/l that corresponds to the target slip amount = Pp + P+ +
Calculate Pa.

In the next step 75, the required release pressure PR(N) obtained in step 62 in FIG. 6 and the final release pressure correction amount P, 7. The target release pressure PR (
M) is calculated.

Step 48 in FIG. 5 is performed at step 51 after the end of the inertia phase (at the end of gear change), which is determined as LFLG~1.
In this case, a command is issued to set the target release pressure PR(M) to 0 and return the torque converter to the lock amplifier state.

In the next step 52, a value obtained by multiplying the deviation between the target release pressure Pi (M) determined in step 50 or 51 and the actual release pressure P by the control constant by 3 is added to the previous release pressure value P.
R(OLD) is added to obtain the current release pressure value PA(NE
Find W). Then, in the next step 53, the solenoid drive current i corresponding to the current release pressure value Pi (NEW) is determined from the table data corresponding to FIGS. 4 and 3 and is supplied to the solenoid 22e.

Note that when the gear shift is completed, step 41 changes to step 54.
-56 are selected in sequence. In step 54, both shift flags 5FLG I and 5FLG II are reset, in step 55, the lock-up flag LFLG is reset, and in step 56, the operating pressure of the friction element is set to the maximum value to prevent this friction element from remaining after the gear shift. to prevent transmission loss.

The above operation will be briefly explained with reference to FIG. In response to the speed change command at instant t, the operating pressure of the corresponding friction element is increased to perform a speed change. As a result, the transmission input/output rotation ratio Nt/No
During the inertia phase from instant 11 when the gear ratio begins to deviate from the pre-shift gear ratio λ2 to instant t3 when the shift ends and reaches the post-shift gear ratio λ1, the torque converter 11 has a slip amount corresponding to the progress of the inertia phase as shown in FIG. The slip is controlled to increase with time, and is placed in a slip control state between the lockup state and the converter state. Then, after the shift is completed at instant t, the release pressure PR
is returned from the value during slip control to 0, and the torque converter can be returned to the lockup state of slip tO.

(Effects of the Invention) As described above, the lock amplifier control device of the present invention is configured to perform slip control on the torque converter so that the amount of slip is between zero and the maximum value in the inertia phase during gear shifting in the lockup region. Since the,
The range of change in the torque converter transmission state is small, and the accompanying shock can be reduced. In addition, even if the shift timing is shifted due to changes in the oil pressure that governs gear shifting, since the above-mentioned slip control is performed in the inertia phase, the gear shifting will always be performed during the slip control, and the gear shifting will be performed by the slip control of the torque converter. It is possible to suppress peak torque and engine revving, and the shock that comes with these can also be reduced.

[Brief Description of the Drawings] Fig. 1 is a conceptual diagram showing the device of the present invention, Fig. 2 is a system diagram showing an embodiment of the present invention, Fig. 3 is a diagram of output pressure change characteristics of a hydraulic actuator in the same example, Fig. 4 is a functional characteristic diagram of the release pressure regulating valve in the same example; Figs. 5 to 7 are flowcharts of the control program executed by the microcomputer in the same example; Fig. 8 is a setting diagram of the target slip amount; FIG. 9 is an operation time chart of the ipsilateral device. 1... Torque converter 2... Automatic transmission 3...
- Inertia phase detection means 4... Slip control means 10... Engine 11.
...Torque converter 11a...Pump impeller (input element) 11b...
Turbine runner (output element) lid...Lock-up clutch 12...Gear transmission mechanism 17.18...Pressure reducing valve 20...Apply pressure circuit 21...Pilot pressure circuit 22...Hydraulic actuator 23. ... Release pressure regulating valve 24 ... Release pressure circuit 25 ... Microcomputer 26, 27 ... Oil pressure sensor 28 ... Negative pressure sensor 29 ... Engine rotation sensor 30 ... Turbine rotation sensor 31 ... Output rotation sensor patent applicant Nissan Motor Co., Ltd. Representative patent attorney Akatsuki Sugimura Examiner Patent attorney Oki Sugimura Author No. 1
figure? () Lukcomparg) Fig. 3 Fig. 4 Hydraulic pressure (Pa) Fig. 7

Claims (1)

[Scope of Claims] 1. In an automatic transmission that includes a torque converter in the power transmission system and is capable of appropriately limiting the amount of slip between input and output elements of the torque converter, in a lockup region where the amount of slip is to be reduced to zero. an inertia phase detection means for detecting an inertia phase during a gear shift; and a slip control means for performing slip control on the torque converter during the inertia phase so that the slip amount is between zero and a maximum. A lock-up control device for an automatic transmission characterized by: