JP3424161B2 - Transmission control device for automatic transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission, and more particularly to a device for controlling the engagement of friction elements to be engaged during gear shifting so that the gear ratio changes smoothly.

[0002]

2. Description of the Related Art An automatic transmission is, for example, Nissan Motor Co., Ltd.
As described in the issued “RE4R01A Automatic Transmission Maintenance Manual”, the power transmission of the gear transmission system is performed by selectively hydraulically operating (engaging) multiple friction elements for shifting such as clutches and brakes. It is configured to determine a path (gear stage) and switch the friction element to be operated to perform gear shifting to another gear stage.

In this gear shifting, the engagement of the friction elements needs to proceed so that the gear ratio represented by the transmission input / output rotation ratio changes smoothly from the gear ratio before gear shift to the gear ratio after gear shift, or else. For example, a sudden change in the gear ratio will cause a large gear shift shock, detracting from the commercial value of the automatic transmission.
If only for solving this problem, it is possible to easily solve the problem by advancing the engagement of the friction element as slowly as possible, but in this case, the shift time required for the shift becomes long, and the feeling of extension during the shift is accompanied, This also reduces the commercial value of the automatic transmission.

[0004]

Various attempts have heretofore been made to control the hydraulic fluid pressure, which controls the engagement of the friction elements, so that the above-mentioned contradictory requirements are both satisfied. The gear ratio represented by the transmission input / output rotation ratio changes from the gear ratio before shifting to the gear ratio after shifting Since the same control method is used throughout the inertia phase, it is not necessary to reduce shift shock. It was hard to say that it was properly implemented in relation to time.

According to a first aspect of the present invention, the inertia phase is divided into an early phase and a late phase, and in the initial phase of the inertia phase, the hydraulic fluid pressure that controls the engagement of the friction elements is used as a predetermined constant shelf pressure to shift gears, and the inertia phase is advanced. In the latter half of the period, the hydraulic pressure is feedback-controlled so that the gear ratio smoothly converges to the gear ratio after shifting, so that the gear shifting time can be optimized by appropriately setting the constant shelf pressure at the beginning of the inertia phase, and the inertia phase An object of the present invention is to propose a shift control device for an automatic transmission, which can surely suppress shift shock by feedback control of hydraulic fluid in the latter half of the period, and thereby realize both reduction of shift shock and appropriate shift time. And

According to the second aspect of the present invention, it is possible to easily determine the tendency of the gear ratio change in the initial phase of the inertia phase used when obtaining the target gear ratio for the feedback control of the hydraulic pressure in the latter half of the inertia phase. It is an object of the present invention to propose a shift control device for an automatic transmission as described above.

A third aspect of the present invention proposes a shift control device for an automatic transmission, which is capable of suitably obtaining a target gear ratio for feedback control of hydraulic fluid in the latter half of the inertia phase. With the goal.

According to a fourth aspect of the present invention, the friction coefficient of the facing constituting the friction element varies even if the constant shelf pressure is properly set at the initial stage of the inertia phase, and the control by the shelf pressure control system is performed. In the case where the shift time varies due to variations in pressure or the like, by preventing the shift time from varying and maintaining an appropriate shift time, the above compatibility cannot be achieved. It is an object of the present invention to propose a shift control device for an automatic transmission that does not require such a thing.

[0009]

For these purposes, first, a shift control device for an automatic transmission according to a first aspect of the present invention has a shift performed by engaging a certain friction element in a released state due to an increase in hydraulic fluid pressure. In the automatic transmission described above, the gear ratio represented by the transmission input / output rotation ratio changes from the pre-gear gear ratio to the post-gear gear ratio during the gear shift.In the initial phase of the inertia phase during the set time from the start of the inertia phase The working fluid pressure is maintained at a predetermined constant shelf pressure, and feedback control is performed in the latter half of the inertia phase so that the target working gear ratio in the latter half of the inertia phase obtained from the tendency of the gear ratio change in the beginning of the inertia phase is achieved. It is characterized by having a configuration.

Also, in the shift control device for an automatic transmission according to a second aspect of the present invention, in the first aspect of the present invention, the tendency of the gear ratio change at the beginning of the inertia phase is calculated from the gear ratio at the start of the inertia phase at the start of the latter half of the inertia phase. It is characterized in that the determination is made based on the time change gradient of the gear ratio to the gear ratio.

Further, in a shift control device for an automatic transmission according to a third aspect of the present invention, in the first or second aspect of the invention, the gear ratio change from the gear ratio at the start of the latter half of the inertia phase to the post-shift gear ratio is smooth. It is characterized in that the gear ratio that forms the following curve is set as the target gear ratio in the latter half of the inertia phase.

Further, in the shift control device for an automatic transmission according to the fourth aspect of the present invention, in any one of the first to third aspects of the invention, the inertia phase time from the start of the inertia phase to the end of the shift becomes a predetermined inertia phase time. The present invention is characterized in that the predetermined constant shelf pressure is learned and controlled.

[0013]

When a certain friction element is engaged from the released state by increasing the hydraulic fluid pressure, the automatic transmission performs a corresponding gear shift. In this first gear change, the gear ratio represented by the transmission input / output rotation ratio changes from the pre-gear gear ratio to the post-gear gear ratio in the first aspect of the invention. The gear ratio is maintained in the latter half of the inertia phase, and the target gear ratio in the latter half of the inertia phase is obtained from the tendency of the gear ratio change in the initial phase of the inertia phase. Feedback control so that

Therefore, according to the first aspect of the present invention, the gear shift time is made appropriate by appropriately setting the constant shelf pressure in the initial phase of the inertia phase, and the gear shift shock is surely suppressed by the feedback control of the hydraulic pressure in the latter phase of the inertia phase. However, it is possible to realize both reduction of shift shock and appropriate shift time.

In the second aspect of the invention, the tendency of the gear ratio change at the beginning of the inertia phase is judged by the time change gradient of the gear ratio from the gear ratio at the start of the inertia phase to the gear ratio at the start of the latter half of the inertia phase. , The tendency of the gear ratio change in the initial phase of the inertia phase, which is used when the target gear ratio for feedback control of the hydraulic fluid in the latter half of the inertia phase is obtained, can be easily determined, and the effect of the first invention can be achieved at low cost. be able to.

In the third aspect of the present invention, when the target gear ratio in the latter half of the inertia phase is obtained, the change of the gear ratio from the gear ratio at the start of the latter half of the inertia phase to the gear ratio after shifting becomes a smooth quadratic curve. Since the gear ratio is set to the target gear ratio, the target gear ratio for feedback control of the hydraulic fluid in the latter half of the inertia phase can surely reduce the shift shock, and the operational effects of the first invention are further improved. You can be sure.

According to the fourth aspect of the present invention, the constant shelf pressure is learned and controlled so that the inertia phase time from the start of the inertia phase to the end of the shift becomes a predetermined inertia phase time. That is, in the configurations of the first to third inventions, even if the constant shelf pressure in the initial phase of the inertia phase is appropriately set, there is variation in the friction coefficient of the facing that constitutes the friction element, or the control pressure by the shelf pressure control system. If there is a variation in the gear shift time, the shift time varies due to the variation of the inertia phase time, so that the above-described effect of optimizing the shift time is not obtained. However, in the fourth invention, Since it is possible to guarantee that the inertia phase time is kept at a predetermined inertia phase time, it is possible to avoid the problem that the shift time varies, and even in such a case, the compatibility can be realized.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a power train of a vehicle equipped with a shift control device for an automatic transmission according to an embodiment of the present invention. 1 is an engine, 2 is an automatic transmission, and the power train of the vehicle is configured by tandem connection thereof. To do. The engine 1 has an accelerator pedal 3 operated by a driver.
It is assumed that the output is adjusted by the throttle valve 4 whose opening degree increases from full closing to full opening as the pedal is depressed, and the engine output is input to the automatic transmission 2 via the torque converter T / C.

The automatic transmission 2 directly controls the hydraulic pressure to be supplied to friction elements such as a hydraulic clutch and a hydraulic brake that determine the power transmission path (shift stage) of the gear transmission system. Therefore, the control valve 5 for gear shift control is provided with the hydraulic fluid pressure duty solenoids 6, 7, and 8 as many as the friction elements. These hydraulic fluid pressure duty solenoids 6, 7, and 8 individually control the hydraulic fluid pressures of the corresponding friction elements to selectively engage and actuate the friction elements so that the automatic transmission 2 is operated at a predetermined gear. Allow it to be in the selected state. Then, the automatic transmission shifts and outputs the engine power at a gear ratio according to the selected shift stage.

The drive duty of the duty solenoids 6, 7 and 8 is determined by a controller 11, and this controller outputs a signal from a throttle opening sensor 12 for detecting the opening TVO of the throttle valve 4 and a signal from the automatic transmission 2. A signal from the output rotation sensor 13 that detects the output rotation speed N _o , a signal from the engine rotation sensor 14 that detects the engine rotation speed N _e , and an input rotation speed N of the automatic transmission 2.
A signal from the input rotation sensor 15 that detects _i is input.

The controller 11 inputs the above-mentioned input information.
2 based on the control program shown in FIG.
Shift control shall be performed as shown below. First step 21
At throttle opening TVO and transmission output rotation
Number N _oRead, and the transmission output speed N_oTo vehicle speed
Calculate VSP.

In the next step 22, shift determination is performed as follows. That is, based on the vehicle speed VSP and the throttle opening TVO, a shift stage suitable for the current driving state is obtained from a planned shift pattern not shown, and the thus-obtained preferable shift stage and the currently selected shift stage are obtained. If and are in agreement, the control is ended without changing the speed as a matter of course. If the current selected shift speed is different from the preferred shift speed, the control proceeds to step 23 to issue a shift command, and the drive duty of the duty solenoids 6, 7, 8 is changed to change the selected shift speed from the selected shift speed. The friction element is released and engaged so that the gear is shifted to a suitable gear.

By the way, in the present embodiment, the change
At the speed, the friction that should be switched from the released state to the engaged state.
During the inertia phase of the rubbing element (fastening side friction element)
Working hydraulic pressure command value P_CThe control shown in FIGS. 3 and 4.
By executing the program, it is decided as shown in FIG.
In addition, in FIG.
Connection side hydraulic fluid command value P _CTo make a conclusion
At the same time, it should switch from the engaged state to the released state
The friction element (release side friction element) is changed to hydraulic fluid (hereinafter, release side
Hydraulic pressure command value P_OSaying) to release the hook
The upshift shift is shown. Here in the figure,
Stun from the instant of gear change command to the instant of torque phase start
Initiation from the bi-phase and torque phase start instants
-During the torque phase until the moment the shear phase starts,
Hydraulic pressure command value P for both friction elements_C, P_ORespectively
For example, a method known in JP-A-9-196158
These standby fades will be decided by
Hydraulic pressure control in phase and torque phase
It has nothing to do with the control in the inertia phase according to the present invention.
Therefore, the explanation is omitted.

FIG. 3 shows a control mode of the engagement side working hydraulic pressure command value P _C and the release side working hydraulic pressure command value P _{O at} the beginning of the inertia phase during the set time ΔT _F from the instant when the inertia phase starts in FIG. Machine input / output rotation ratio (N _i / N
Gear ratio g _r represented by _O) control program of FIG. 3 when determining the start of the inertia phase as it becomes inertia phase start determination gear ratio g ₁ shown in FIG. 5 shall be initiated.

In step 31, the flag FLAG is set to 1 to indicate that the inertia phase has just started. Therefore, the flag FLAG
If the step 32 for checking is immediately after the start of the inertia phase, the control is advanced to the steps 33 to 37. Therefore, the loop including these steps 33 to 37 is executed only once because the flag FLAG is reset to 0 in step 37.

To explain the loop of steps 33 to 36, in step 33, the timer TM is reset to 0 so that the elapsed time from the instant of starting the inertia phase of FIG. 5 can be measured. Next, at step 34, the transmission input torque is calculated as follows. That is, first, the speed ratio (N _i / N _e ) of the torque converter T / C is obtained from the engine speed N _e and the transmission input speed N _i , and the torque ratio and the torque ratio are calculated from this and the characteristic diagram of the torque converter. The torque capacity coefficient is obtained, and the output torque (transmission input torque) of the torque converter T / C is calculated by multiplying the torque ratio and the torque capacity coefficient.

In step 35, a map is searched from the input torque of the transmission for a corresponding fixed hydraulic pressure command value P _{C on} the engaging side hydraulic pressure P _C1 illustrated in FIG. The feedback control start gear ratio g _{2 according} to is searched. Next, at step 37, the flag FLAG is reset to 0 as described above.

Thereafter, step 32 advances the control to step 38 by resetting the flag FLAG. In step 38, the timer TM is incremented to advance by the calculation cycle ΔT of the control program, and the elapsed time from the instant when the inertia phase starts in FIG. 5 is measured.

In the next step 39, the constant hydraulic pressure command value P _C on the engagement side is retrieved at step 35 and the constant shelf pressure P _{C1 is obtained.}
Maintaining the duty solenoid 6 or 7, the corresponding this, or instruct the 8 commands the duty solenoid 6 or 7, or 8, the corresponding this by the disengagement side hydraulic fluid pressure command value P _O 0 simultaneously . In step 40, the gear ratio g _r is determined whether led to the feedback control start gear ratio g _2, repeat the loop through steps 32,38,39,40 otherwise, the at this moment. Thus, as shown in FIG. 5, the inertia phase from the start instant to the instant when the gear ratio g _r reaches the above feedback control start gear ratio g _2, the engagement-side hydraulic fluid pressure command value P _C constant shelf pressure P _C1 Therefore, the release side hydraulic fluid command value P _O is set to 0.

From the moment when the inertia phase starts, the gear ratio g
_rIs the feedback control start gear ratio g₂The moment it reached
After that, the control proceeds to step 41, where as shown in FIG.
G _r= G₂The value of the timer TM at the moment
Nasha phase initial time ΔT_FMemory, then switch
At the step 42, the control shifts to the latter half of the inertia phase.
To go.

The control in the latter half of the inertia phase is as shown in FIG.
M is incremented and the elapsed time from the start of the inertia phase is continuously measured. In step 52, the inertia phase start instant after, the tendency of change gear ratio g _r in the inertia phase during the initial period [Delta] T _F between up gear ratio g _r is the feedback control start gear ratio g _2, in the inertia phase Late The target gear ratio f (t) for the feedback control of the engagement side hydraulic fluid command value P _C to be performed is calculated.

When calculating the target gear ratio f (t)
Is the inertia phase start gear ratio g ₁And inertia
Phase late start Gear ratio g₂And the gear ratio after shifting g₃When,
Initial time of inertia phase ΔT_FAnd f (t) = at²+ Bt + c However, a = (g₁-G₂)²/ {4 (g₂-G₃) ΔT
_F ²} b = {g₂ ²-G₁ ²+ 2g₃(G₁-G₂)} / {2
(G₂-G₃) ΔT_F} c = g₁+ (G₁-G₂)²/ 4 (g₂-G₃) The target gear ratio f (t) is calculated by

The target gear ratio f obtained by such calculation
(T) will be described with reference to FIG. 5. From the inertia phase start gear ratio g ₁ to the inertia phase late start gear ratio g
_The gear ratio g to the _two- dot chain line α representing the time-varying gradient of the gear ratio to ₂ and the one-dot chain line β representing the gear ratio after gear change g ₃ respectively.
Corresponds to the gear ratio on the quadratic curve that touches at ₂ and g ₃ ,
The gear ratio is such that the change in the gear ratio from the gear ratio g ₂ after the start of the inertia phase to the gear ratio g ₃ after the shifting becomes a smooth quadratic curve.

At step 53, the actual gear ratio g _r = N _i / N
_O is calculated, in step 54, the actual gear ratio g _r
Is calculated by feedback control to obtain the engagement side hydraulic fluid pressure command value P _C that causes the above-mentioned target gear ratio f (t) to follow.
This is instructed to the corresponding duty solenoid 6, 7 or 8, and at the same time the release side hydraulic fluid command value P _{O is set} to 0.
Then, this is instructed to the corresponding duty solenoid 6, 7 or 8. Loop, the actual gear ratio g _r continues to determine the shift end instantly reaches the post-shift gear ratio g ₃ at step 55 including the above steps 51 to 54,
Thus during the inertia phase late from the inertia phase late initial instant, as shown in FIG. 5 to the shift end, the actual gear ratio g _r a smooth post-shift gear ratio g ₃ so as to follow a target gear ratio f (t) Can be reached.

When it is determined in step 55 that the shift is completed, the value of the timer TM at the end of the shift is stored as the inertia phase time TM _IF (see FIG. 5) in step 56, and in step 57, the engagement side operation is performed. At the same time as instructing the hydraulic pressure command value P _C to the original line pressure P _L to completely engage the engagement side friction element, the release side working hydraulic pressure command value P _O is continuously set to 0 and the release side friction element is set. Let's release.

Thereafter, in steps 58 to 60, as will be described below, a constant shelf pressure P for each transmission input torque is obtained.
_C1 is learned and controlled based on the inertia phase time TM _IF stored in step 56. In step 58,
It is determined whether or not the inertia phase time TM _IF is equal to or greater than the inertia phase time set value TM _IFS. If it is, the constant shelf pressure P _C1 is too low. Therefore, in step 59, this is increased by a predetermined amount ΔP _C1 and updated. And contribute to the next control. On the other hand, if TM _IF <TM _IFS , the constant shelf pressure P _C1 is too high, so in step 60 this is reduced by a predetermined amount ΔP _C1 and updated, which contributes to the next control. By this learning control of the constant shelf pressure P _C1 , the inertia phase time TM
_{The IF} can be maintained at the set value TM _IFS .

According to the present embodiment described above, during gear shifting, the gear ratio represented by the transmission input / output rotation ratio changes from the gear ratio before gear shift to the gear ratio after gear shift from the start of the inertia phase to the gear shift. in the inertia phase early to time the ratio g _r reaches the feedback control start gear ratio g ₂ (measurement time in [Delta] T _F in FIG. 5), constant engagement side hydraulic fluid pressure command value P _C of a predetermined by the process shown in FIG. 3 The gear shift is carried out while maintaining the shelf pressure P _C1 (step 39), and in the latter half of the inertia phase thereafter, the hydraulic fluid pressure is changed by the processing shown in FIG. 4 from the gear ratio change tendency in the initial phase of the inertia phase (see α in FIG. 5). Since feedback control is performed so that the obtained target gear ratio f (t) in the latter half of the inertia phase is achieved (step 54), the constant shelf pressure in the initial phase of the inertia phase is obtained. While in the shift time by appropriate setting of the _C1 suitable to reliably suppress the shift shock by the feedback control of the engagement side hydraulic fluid pressure in the inertia phase Late (command value P _C) (step 54),
It is possible to achieve both reduction of shift shock and appropriate shift time.

In addition, particularly in the present embodiment, the tendency of the gear ratio change in the initial phase of the inertia phase is shown in FIG.
As indicated by α in Fig. ₂ , since it was decided to judge by the average time change gradient of the gear ratio from the gear ratio g ₁ at the start of the inertia phase to the gear ratio g ₂ at the start of the latter phase of the inertia phase, In this case, it is possible to easily determine the gear ratio change tendency in the initial phase of the inertia phase used for obtaining the target gear ratio f (t) for the feedback control of the engagement side hydraulic fluid (command value P _C ). The effect can be achieved.

[0039] Particularly in this embodiment, upon obtaining the inertia phase late target gear ratio f (t), after shifting from the gear ratio g ₂ at the beginning of the street inertia phase Late described above per step 52 of FIG. 4 In order to set the target gear ratio to a gear ratio such that the gear ratio change to the gear ratio g ₃ is a smooth quadratic curve, feedback control of the engagement side hydraulic fluid (command value P _C ) in the latter half of the inertia phase is performed. Thus, the target gear ratio f (t) for reducing the shift shock can be surely reduced, so that the above-described effects can be further ensured.

Further, particularly in the present embodiment, the inertia phase time TM _IF from the start of the inertia phase to the end of the gear shift (see step 56 in FIG. 4 and FIG. 5) becomes a predetermined inertia phase time TM _IFS. Learning control of the constant shelf pressure P _C1 of
To 60), the following operational effects can be obtained. That is,
When the learning control is not performed, even if the constant shelf pressure P _{C1 in} the initial phase of the inertia phase is appropriately set, the friction coefficient of the facing that constitutes the engagement side friction element varies, or the control pressure by the shelf pressure control system varies. However, in the case of the present embodiment, it becomes impossible to obtain the above-mentioned effect of optimizing the earliest gear shifting time because the gear shifting time varies due to the variation of the inertia phase time TM _IF. Even if the inertia phase time TM _IF is the predetermined inertia phase time TM
_Since it can be guaranteed that the _IFS is maintained, it is possible to avoid the problem that the shift time varies, and even in such a case, it is possible to assure compatibility of both the above-mentioned effects.

[Brief description of drawings]

FIG. 1 is a system diagram showing a power train of a vehicle including a shift control device for an automatic transmission according to an embodiment of the present invention and a control system thereof.

FIG. 2 is a flowchart showing a main routine of a shift control program to be executed by a controller in the same embodiment.

FIG. 3 is a flow chart showing a control program in the initial phase of the inertia phase of the hydraulic fluid command value of the engagement side friction element, which should be switched from the released state to the engaged state in the same shift control.

FIG. 4 is a flowchart showing a control program in the latter half of the inertia phase regarding a hydraulic fluid command value of the engagement side friction element.

FIG. 5 is a time chart showing a time series change relating to a hydraulic fluid command value of the engagement side friction element together with a time series change relating to a hydraulic fluid pressure of a release side friction element to be released at this time.

[Explanation of symbols]

1 engine 2 automatic transmission 3 accelerator pedal 4 Throttle valve 5 control valves 6 Duty solenoid 7 Duty solenoid 8 duty solenoid 11 Controller 12 Throttle opening sensor 13 Transmission output rotation sensor 14 Engine rotation sensor 15 Transmission input rotation sensor

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-2-80853 (JP, A) JP-A-2-57438 (JP, A) JP-A-1-169164 (JP, A) JP-A-6- 159493 (JP, A) JP 9-196158 (JP, A) Actual development 1-118242 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 59/00-61 / 12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (4)

(57) [Claims] 1. An automatic transmission having a shift that is performed by engaging a certain friction element in a released state due to an increase in hydraulic fluid pressure, wherein a gear ratio represented by a transmission input / output rotation ratio is changed during the shift. Changing from the front gear ratio to the post-shift gear ratio From the start of inertia phase during the set time, the hydraulic fluid pressure is maintained at a predetermined constant shelf pressure at the beginning of the inertia phase, and the hydraulic fluid pressure is maintained at the later inertia phase. A shift control device for an automatic transmission, which is configured to perform feedback control so that a target gear ratio in the latter half of the inertia phase, which is obtained from a gear ratio change tendency in the initial phase of the inertia phase, is achieved. 2. The gear ratio change tendency in the initial phase of the inertia phase is determined according to a temporal change gradient of the gear ratio from the gear ratio at the start of the inertia phase to the gear ratio at the start of the latter phase of the inertia phase. A shift control device for an automatic transmission, which is configured as described above. 3. The gear ratio according to claim 1 or 2, wherein the gear ratio at the start of the latter half of the inertia phase becomes a smooth quadratic curve from the gear ratio to the post-shift gear ratio. A shift control device for an automatic transmission, which is configured to have a target gear ratio. 4. The structure according to claim 1, wherein the predetermined constant shelf pressure is learned and controlled so that the inertia phase time from the start of the inertia phase to the end of the shift becomes a predetermined inertia phase time. A shift control device for an automatic transmission characterized by the above.