JP2002168335A - Method of variable speed control of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of a variable speed control for controlling the reduction of the toque of an output shaft of an automatic transmission as much as possible during a gearshift without extending the gearshift time. SOLUTION: The automatic transmission 10 shifts gears from the forward fourth speed stage to the forward fifth speed stage by reducing oil pressure on a release side inside a release side friction element C1 and increasing the oil pressure on an engagement side inside an engagement side friction element C3. For shifting gears in the automatic transmission 10, the reduction grade of the oil pressure on the release side gradually becoming gentle with the passage of time is set based on the torque of the input shaft 11, and the oil pressure on the release side is feed-forward controlled so that the oil pressure on the release side is reduced according to the set reduction grade. After that, the oil pressure is feedback-controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control method for an automatic transmission, and more particularly to clutch-to-clutch control.

[0002]

2. Description of the Related Art As a technique showing conventional clutch-to-clutch control, there is a technique disclosed in Japanese Patent Application Laid-Open No. 11-82721. This publication discloses that the torque capacity of the disengagement clutch is gradually decreased by the disengagement hydraulic control mechanism, and the torque capacity of the engagement clutch is gradually increased by the engagement hydraulic control mechanism. A shift control device for an automatic transmission for performing a shift by re-engaging an engagement-side clutch, comprising control means for giving a control command of an engagement-side clutch oil pressure to an engagement-side hydraulic control mechanism, and the control means However, during the period until the inertia phase starts, after a variable first hydraulic pressure command is given to the on-coming clutch to adjust the clutch re-engaging timing for a predetermined time, By providing a second oil pressure command for maintaining a variable oil pressure to adjust the torque capacity of the engagement side clutch of
There is disclosed a technique for properly adjusting the clutch-to-clutch grip change timing without extending the shift time. According to this technique, the clutch on the engagement side is adjusted by the first hydraulic pressure command and then the torque capacity is adjusted by the second hydraulic pressure command so that the clutch can be gripped without prolonging the shift time. Timing can be appropriately controlled.

[0003]

However, the above-mentioned prior art is a control for shortening the shift time and suppressing the absolute amount of the engine rising, so that even if the absolute amount of the rising is suppressed, the engine is not controlled. Immediately after the occurrence of a blow-up, the rise of the blow-up (the amount of blow-up per unit time) may be large. In such a case, there is a problem that the torque of the output shaft of the automatic transmission decreases rapidly, and the driver feels a sense of incongruity during the shift, and the shift feeling deteriorates. This problem can be solved to some extent by gradually reducing the hydraulic pressure of the disengagement clutch.However, in this case, the shift time is prolonged, which also leads to a deterioration in the shift feeling. Is not preferred.

[0004] In order to solve the above-mentioned problems, the present invention provides a shift control method that minimizes a decrease in the torque of the output shaft of an automatic transmission during a shift and that does not prolong the shift time. Is a technical task.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention of claim 1 reduces the release hydraulic pressure in the release friction element and increases the engagement hydraulic pressure in the engagement friction element. Thus, in the shift control method for an automatic transmission that shifts from the first shift speed to the second shift speed, when shifting from the first shift speed to the second shift speed, the speed is gradually reduced with time. Is set based on the torque of the input shaft of the automatic transmission, and the feed-forward control is performed so that the release-side hydraulic pressure decreases at the set reduction slope, and then the release-side hydraulic pressure is feedback-controlled. And a shift control method for an automatic transmission.

According to the first aspect, the second shift from the first shift stage is performed.
When the gear is shifted to the first gear, during the feedforward control, the decreasing gradient of the release hydraulic pressure is set so as to be gradually gradual, so at the initial stage of the feedforward control, the release hydraulic pressure decreases relatively quickly. As the feedforward control ends, the release hydraulic pressure decreases slowly. Thus, the torque of the output shaft of the automatic transmission does not rapidly decrease until the shift to the feedback control, and the torque of the output shaft decreases relatively slowly. Further, since the decreasing gradient of the release hydraulic pressure is set based on the torque of the input shaft of the automatic transmission, it is possible to perform appropriate feedforward control according to various shift situations. Therefore, the driver's uncomfortable feeling during the shift is suppressed, and the shift feeling is improved. Further, according to the shift control method of the first aspect, such an effect is exerted only by controlling the disengagement hydraulic pressure, so that it is not necessary to control the engagement hydraulic pressure intricately as in the above-described related art, which is preferable. .

More specifically, as set forth in claim 2, the first
At the time of shifting from the first gear to the second gear, when the feedforward time elapses, the rotation speed of the input shaft and the rotation speed obtained by multiplying the output shaft of the automatic transmission by the speed ratio of the first gear are obtained. If the feed-forward time and the decreasing gradient of the release-side hydraulic pressure are set so that the difference reaches the predetermined rotation speed, it is possible to shift to the feedback control when the predetermined rotation speed difference occurs after the feed-forward time has elapsed. Gear shift control can be performed.

A third aspect of the present invention specifically shows the second aspect of the present invention, in which, when shifting from the first shift speed to the second shift speed, the release-side hydraulic pressure is changed when the feed-forward time elapses. When the hydraulic pressure is reached, the release side at the end of the feedforward control is adjusted so that the difference between the rotation speed of the input shaft and the rotation speed obtained by multiplying the output shaft of the automatic transmission by the gear ratio of the first gear position reaches a predetermined rotation speed. By setting the hydraulic pressure based on the torque of the input shaft, it is possible to shift to the feedback control when the feedforward time has elapsed and a predetermined rotational speed difference has occurred.

Further, as set forth in claim 4, before the elapse of the feedforward time, the rotational speed of the input shaft and the rotational speed of the output shaft of the automatic transmission are multiplied by the speed ratio of the first shift stage. When the difference between the rotation speeds of the input shaft reaches a predetermined rotation speed, feedback control is started from that point, for example, due to some disturbance during the feedforward control, the gear ratio is increased to the rotation speed of the input shaft before the elapse of the set feedforward time. Even if the difference between the number of revolutions multiplied by and the number of revolutions of the output shaft reaches a predetermined number of revolutions, at this time, the shift to the feedback control is performed promptly, so that the appropriate shift control according to the state can be performed. Can be performed.

Specifically, the gradient of the decrease in the release hydraulic pressure during the feedforward control of the present invention becomes gentler as the time from the start to the end of the feedforward control elapses. Is set by combining a plurality of decreasing gradients of different gradients.

Further, immediately after the start of the feedforward control, the release-side hydraulic pressure is rapidly reduced to a predetermined release-side hydraulic pressure, and the predetermined release-side hydraulic pressure is maintained for a predetermined time. Until the forward control is completed, if the release hydraulic pressure is decreased at the set decreasing gradient, a time margin is provided for the actual release hydraulic pressure to follow a sudden decrease in the release hydraulic pressure, Control with higher accuracy can be performed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram including an automatic transmission controlled by a shift control method according to the present embodiment and a mechanism around the automatic transmission.

The automatic transmission shown in FIG.
Automatic transmission 10 connected to output shaft 0 (not shown)
And a hydraulic control unit 3 shown in the hydraulic circuit diagram of FIG. 2 for controlling the supply and discharge of hydraulic pressure to five hydraulically driven friction elements incorporated in the automatic transmission 10 shown in the skeleton diagram of FIG.
00 and an electronic control unit 400 for controlling the operation of a plurality of solenoid valves in the hydraulic control unit 300.

The automatic transmission 10 includes a torque converter 2
, An output shaft 12 connected to an axle via a differential (not shown), a first row of double pinion planetary gears G1 having a sun gear connected to the input shaft 11, and a second row. Single pinion planetary gear G2 and third row single pinion planetary gear G
3, five friction elements of a first friction clutch C1, a second friction clutch C2, a third friction clutch C3, a first friction brake B1, and a second friction brake B2, A one-way clutch F1 is provided, and the supply of the hydraulic pressure to the five friction elements is switched by the hydraulic control unit 300 and the electronic control unit 400 to achieve the sixth forward speed and one reverse speed.

Next, the main configuration of the hydraulic control unit 300 will be described with reference to the hydraulic circuit diagram of FIG. Hydraulic control unit 3
Reference numeral 00 denotes an oil pump 20, a regulator valve 30 for generating a line pressure, a modulator valve 40 for reducing the line pressure, a manual valve 50 for switching a travel range by operating a manual lever (not shown), and a regulator valve 30. A linear solenoid valve 6 which is a first solenoid valve that outputs an adjustment pressure corresponding to a current supplied by using a hydraulic pressure from an oil pump 20 through the linear solenoid valve 6
0, 70, 80 and linear solenoid valves 60, 7
Control valves 90, 100, and 110 for introducing the adjustment pressure output from 0 and 80 and generating a control pressure to be output in accordance with the introduced hydraulic pressure;
Three fail valves 120, 1 for introducing the control pressure output from 110 to prevent double engagement of the friction elements
30, 140, and fail valves 120, 130, 14
5, five control valves 150, 160, 170, 180 for introducing the control pressure output from the control valves 90, 100, 110 and switching the supply of the control pressure to each friction element according to the supplied hydraulic pressure. , 190, and each shift valve 150, 160, 170,
ON-OFF solenoid valves 200, 21 which are second solenoid valves for switching the positions of 180, 190
0, 220.

The manual valve 50 is a spool valve having a spool 50A which is actuated in the axial direction by a manual lever. The manual valve 50 interlocks with the manual lever to provide a P (parking) range, R (revers) range, N (neutral) range, It can be switched to 7 ranges of D (drive) range, 3 range, 2 range and L (low) range,
In each range, communication between the oil pump 20 and the control valve 90 and communication between the oil pump 20 and the shift valve are switched.

FIG. 3 shows the relationship between the engagement / disengagement of each friction element and the shift speed. Next, a shift control method for an automatic transmission, which is the gist of the present invention, will be described. In the present embodiment,
A description will be given of a case where the first gear is the fourth forward speed and the second gear is the fifth forward speed, and the upshift from the fourth forward speed to the fifth forward speed is performed. In this case, the friction clutch C1 is a release-side friction element, and the friction clutch C3 is an engagement-side friction element. Before the gear shift, a high control pressure controlled by the linear solenoid valve 60 is introduced to the friction clutch C1 via the shift valve, the friction clutch C1 is engaged, and the linear solenoid valve 70 is applied to the friction clutch C3.
Is introduced through the shift valve so as not to engage the friction clutch C3.
When a shift-up shift command from the fourth speed to the fifth speed is output based on the vehicle speed and the throttle opening, energization control of the linear solenoid valves 60 and 70 is performed, and the hydraulic pressure in the friction clutch C1 (release hydraulic pressure). Is reduced to release the friction clutch C1 and increase the hydraulic pressure (engagement hydraulic pressure) in the friction clutch C3, thereby shifting from the fourth forward speed to the fifth forward speed. FIG. 4 shows a time chart of the disengagement hydraulic pressure and the engagement hydraulic pressure at the time of shifting from the fourth forward speed to the fifth forward speed. FIG. 5 is a flowchart illustrating control of the hydraulic pressure (disengagement hydraulic pressure) in the friction clutch C1 according to the shift control in the present embodiment. Control of the release hydraulic pressure will be described with reference to the flowchart of FIG.

First, in step 101, an initial oil pressure P0, an end oil pressure P3,
Final decreasing gradient ΔP3, timers t0, t1, t2 and t3
Set. The torque of the input shaft 11 is calculated based on the turbine speed Nt and the throttle opening θ. Initial oil pressure P
0 indicates the predetermined release-side hydraulic pressure in claim 6, and the timer t0 indicates the predetermined time in claim 6.

In step 102, the decreasing gradient ΔP2 is calculated according to the equation 1, and the decreasing gradients ΔP1 and ΔP2 are calculated.
2 is calculated according to Equations 2 and 3.

[0020]

(Equation 1)

[0021]

(Equation 2) Here, the timer t0 corresponds to the time for maintaining the initial oil pressure P0 from the start of the feedforward control, and the decreasing gradient ΔP
1 is a decreasing gradient of the release side hydraulic pressure from when the timer t0 elapses to when the timer t1 is reached, and the decreasing gradient ΔP2 is the timer t1
, And the decreasing gradient ΔP3 is the decreasing gradient of the releasing hydraulic pressure from when the timer t2 has elapsed until the timer t3. In addition, the feedforward time is determined by the time from when the feedforward control is started to when the timer t3 elapses.
That is, it is the time obtained by adding the timer t0 and the timer t3.

In step 103, the timer t0 is started, and in step 104, the release hydraulic pressure PR is maintained at the initial hydraulic pressure P0. The release hydraulic pressure PR is maintained at P0 until the timer t0 elapses in step 106 or until a slip of a predetermined amount or more is detected in step 105. When the timer t0 has elapsed, the process proceeds to step 107,
The timers t1, t2, t3 are started.

The release-side hydraulic pressure PR is controlled by duty control of energization of the linear solenoid valve 60. In addition, the slip used in the description of the flowchart of the present embodiment is a rotation speed obtained by multiplying the rotation speed of the input shaft 11 and the rotation speed of the output shaft 12 of the automatic transmission by the speed ratio at the fourth forward speed. Step 10 shall indicate the difference.
5 and whether or not there is a slip performed in step 112,
It is to determine whether or not the difference between the rotation speed of the input shaft 11 and the rotation speed of the output shaft 12 multiplied by the speed ratio at the fourth forward speed is equal to or greater than a predetermined rotation speed difference (for example, rpm).

If the timer t1 has not elapsed at step 108, the routine proceeds to step 109, where the current torque of the input shaft 11 is applied to the map of the end pressure P3 at step 101, and the value at this time is used as the base oil pressure P4. Read. This step 109 is a step in consideration of the case where the torque of the input shaft 11 changes during gear shifting. Then, in step 110, the current release-side hydraulic pressure PR (n) is updated according to Expression 3.

[0025]

(Equation 3) Step 110 is the release-side hydraulic pressure PR in the previous calculation process.
This is a step of updating the release-side hydraulic pressure PR by adding the increase / decrease of the hydraulic pressure by the current arithmetic processing to (n-1). Next, proceeding to step 111, step 109
Is replaced with the end pressure P3 as a new end pressure. Then, in step 112, the presence or absence of slip is detected. If there is no slip and the elapsed time is within the range from timer t1 to timer t2, step 11 is executed.
The routine proceeds to step 114 via step 3, reads the base hydraulic pressure P4 in the same manner as in step 109, and updates the release hydraulic pressure in step 115 according to equation 4.

[0026]

(Equation 4) Proceeding again from step 111 to step 112, if there is no slip and the elapsed time is within the range from timer t2 to timer t3, the procedure proceeds to step 117 via step 116, and the base oil pressure P4 is read in the same manner as step 109, and Then, the release side hydraulic pressure is updated according to Equation 5.

[0027]

(Equation 5) If a slip is detected in step 105 or 112 before the timer t3 elapses due to a disturbance such as a change in the state of the vehicle, the process proceeds to step 119, the slip flag is turned on, the feedforward control is ended, and the feedback control is performed. Move to. Although the feedback control is not described in detail, the release-side hydraulic pressure is controlled so that the amount of slip (difference in rotation speed) becomes a target amount.

If the slip is not detected before the timer t3 elapses, the above-mentioned control is repeated, and the timer t3
At the point when 3 has elapsed, the feedforward control ends. This is because the end pressure P3, which is the release hydraulic pressure at which a slip should occur, is set based on the torque of the input shaft 11. In this control, it is assumed that the slip occurs when the timer t3 has elapsed, and the timer t3 When the time elapses, the feedforward control ends, and the process shifts to the feedback control. The feedback control is performed until the slip is no longer detected. In the present embodiment, it is assumed that the feedback control ends when a time t7 elapses after the feedforward control ends.

It is assumed that there is no actual slip even after the elapse of the timer t3. For example, it is determined whether or not a slip has occurred after the elapse of the timer t3. Timer t3
The pressure may be reduced by reducing the pressure on the immediately preceding decrease gradient ΔP3 for a predetermined time, and after a lapse of the predetermined time, the disengagement-side hydraulic pressure may be rapidly reduced and the engagement-side hydraulic pressure may be increased.

The engagement hydraulic pressure of the engagement friction element C3 will be briefly described. When the timer t5 elapses from the start of the shift, the engagement side oil pressure is increased to the initial oil pressure P4 at a stretch, and thereafter, the pressure is gradually increased at a predetermined gradient ΔP4 until the timer t6 elapses. The feed-forward control of the release hydraulic pressure is controlled by the timer t.
After the elapse of 5 and before the timer t6 elapses, the operation is terminated. After the elapse of the timer t6, the engagement side hydraulic pressure is rapidly increased,
When a time t7 has elapsed from that point, the feedback control of the release hydraulic pressure ends, and the shift from the fourth forward speed to the fifth forward speed ends. In the present embodiment, the shift to the fifth forward speed is performed smoothly without controlling the engagement-side hydraulic pressure by performing feedback control of the release-side hydraulic pressure as described above.

As described above, according to the present embodiment,
In shifting from the fourth forward speed to the fifth forward speed, the release-side hydraulic pressure is quickly reduced to the initial hydraulic pressure P0 immediately after the start of the feedforward control. .
Then, since the decreasing gradient of the release-side hydraulic pressure is set so as to become gradually gentle from the elapse of the timer t0 to the time of the timer t3, the output shaft 12 is slowly set immediately after the elapse of the timer t0 and immediately before the end of the feedback control. The torque of the motor decreases. Also, the decreasing gradients ΔP1 and ΔP of the release-side hydraulic pressure
2. Since ΔP3 is set based on the torque of the input shaft 11 of the automatic transmission, it is possible to perform appropriate feedforward control according to the state of shifting. Therefore, the driver's uncomfortable feeling during the shift is suppressed, and the shift feeling is improved.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, when the number of decreasing gradients of the release hydraulic pressure during feedforward control is increased, This enables a smoother shift, which is preferable in terms of performance. Also, reducing the number of decreasing gradients of the release-side hydraulic pressure during feedforward control simplifies control, which is preferable from the viewpoint of control. As described above, any transmission control method may be used as long as the transmission control method conforms to the gist of the present invention.

[0033]

According to the present invention, during the feedforward control, the decreasing gradient of the release side hydraulic pressure gradually becomes gentle, so that immediately after the start of the feedforward control, the shift time is prolonged due to a rapid decrease in the release side hydraulic pressure. Just before the end of the feedforward control, the torque of the output shaft of the automatic transmission does not suddenly decrease and the torque of the output shaft decreases relatively slowly just before the end of the feedforward control. . As a result, the driver's uncomfortable feeling during the shift is suppressed, and the shift feeling is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram including an automatic transmission according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of the automatic transmission according to the present embodiment.

FIG. 3 is a diagram showing a relationship between engagement / disengagement of each friction element and a shift speed.

FIG. 4 is a time chart of a disengagement hydraulic pressure and an engagement hydraulic pressure at the time of shifting from fourth forward speed to fifth forward speed in the present embodiment.

FIG. 5 is a flowchart showing a part of a shift control of the automatic transmission according to the embodiment.

[Explanation of symbols]

2 Torque converter 10 Automatic transmission 11 Input shaft 12 Output shaft 60, 70, 80 Linear solenoid valve 90, 100, 110 Control valve 150, 160 170, 180, 190: shift valves 200, 210, 220: ON-OFF solenoid valves 300: hydraulic control unit 400: electronic control unit C1: release side friction element C3: engagement Mating friction element

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F16H 63:12 F16H 63:12

Claims (7)

[Claims] 1. An automatic transmission that shifts from a first gear to a second gear by reducing the release hydraulic pressure in the release friction element and increasing the engagement hydraulic pressure in the engagement friction element. In the shift control method for a transmission, when the shift from the first shift speed to the second shift speed is performed, the decreasing gradient of the release-side hydraulic pressure, which gradually decreases with time, is input to the automatic transmission. A shift control method for an automatic transmission, comprising: setting based on a torque of a shaft, performing feedforward control so as to decrease the release-side hydraulic pressure at the decreasing gradient, and then performing feedback control of the release-side hydraulic pressure. . 2. A speed change from the first shift speed to the second shift speed, the rotation speed of the input shaft and the output shaft of the automatic transmission, when the feedforward time has elapsed. The decreasing gradient of the feedforward time and the release-side hydraulic pressure is set so that a difference between the rotation speed and the rotation speed multiplied by the speed ratio of the shift stage reaches a predetermined rotation speed. Shift control method for an automatic transmission. 3. When the release hydraulic pressure reaches the release hydraulic pressure at the time when the feedforward time has elapsed during the shift from the first gear position to the second gear position, the rotational speed of the input shaft is increased. The release-side hydraulic pressure at the end of the feedforward control is set to the torque of the input shaft so that the difference between the output shaft of the automatic transmission and the rotation speed obtained by multiplying the transmission ratio of the first shift speed reaches a predetermined rotation speed. The shift control method for an automatic transmission according to claim 2, wherein the shift is set based on: 4. A difference between a rotational speed of the input shaft and a rotational speed obtained by multiplying a rotational speed of an output shaft of the automatic transmission by a speed ratio of the first shift stage before a lapse of the feedforward time is predetermined. 4. The shift control method for an automatic transmission according to claim 2, wherein the feedback control is started when the rotation speed is reached. 5. The decreasing gradient of the release-side hydraulic pressure during the feedforward control includes a plurality of decreasing gradients different from each other such that the decreasing gradient decreases as the time from the start to the end of the feedforward control elapses. Characterized by being set by combining
The shift control method for an automatic transmission according to claim 1. 6. Immediately after the start of the feedforward control, the release-side hydraulic pressure is rapidly reduced to a predetermined release-side hydraulic pressure, and the predetermined release-side hydraulic pressure is maintained for a predetermined time, and after the predetermined time has elapsed, the feedforward control ends. The shift control method for an automatic transmission according to any one of claims 1 to 5, wherein the release-side hydraulic pressure decreases at the decreasing gradient until the release-side hydraulic pressure decreases. 7. The automatic transmission according to claim 6, wherein the predetermined release-side hydraulic pressure immediately after the start of the feedforward control is set based on a torque of an input shaft of the automatic transmission. Transmission control method.