JPH05296332A - Speed change control method of vehicular automatic transmission - Google Patents

Abstract

PURPOSE:To take measures not to sense any incompatibility to speed change feeling by restraining the overshoot of an engine speed below an allowable maximum engine speed stably, even in the case of the generation of endurance inferiority of a friction engagement element and the start up delay of a supply oil pressure and the like. CONSTITUTION:An elapsed time Tst from a basic point before the start point of an actual speed change upto the actual speed change start point is measured and the measured elapsed time is compared with a prescribed discriminated value. When the elapsed time is bigger than the prescribed discriminated value, the increase rate of an oil pressure supplying to a second friction engagement element is increased so as to wait the actual speed change start. Accordingly, the generation of the transmission torque of a connection side clutch or the start up of the supply oil pressure and also the reach to the speed change start point of an inertia phase become quick and then the excess revolution of an engine is prevented. An excess revolution watching routine is operated as the backup of an usual speed change control and an abnormal speed change control by which an overshoot amount becomes big can be eliminated and the engine maximum speed in a speed change time can be restrained below an allowable maximum engine speed stably.

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 for a vehicle, and more particularly to a shift control method for preventing the engine speed from rising during an upshift.

[0002]

2. Description of the Related Art An automatic transmission for a vehicle has a large number of friction engagement elements such as hydraulically operated clutches and brakes.
For example, when performing an upshift, the friction engagement element of the established low speed side gear stage is disengaged, while the friction engagement element of the high speed side gear stage to be established is engaged. Then, the friction engagement elements are switched.
When switching the friction engagement elements as described above, a shift shock occurs if engagement of the friction engagement elements on the coupling side is too fast, while coupling is performed even if the engagement of the friction engagement elements on the release side is completely released. If the engagement of the side frictional engagement element does not start, the engine speed may rise during gear shifting and exceed the maximum allowable engine speed. Therefore, the bearing transmission torques of the disengagement-side and engagement-side frictional engagement elements are optimized to prevent the above-described overshoot of the engine speed and shift shock during gear shifting.

In order to frictionally engage the frictional engagement element on the coupling side, the frictional engagement element is moved from the standby position where the engagement is completely released to the standby position to the position immediately before the transmission torque is generated. The stroke is performed, and then the hydraulic pressure supplied to the coupling side frictional engagement element is gradually increased at a predetermined increase rate to start the engagement of the coupling side frictional engagement element. Then, waiting for the input shaft rotation speed of the automatic transmission to reach the actual shift start point, and when the input shaft rotation speed reaches the actual shift start point, feedback control of the transmission torque of the coupling side friction engagement element is performed, The input shaft rotation speed is reduced toward the synchronous rotation speed so that the input shaft rotation speed change rate matches the target change rate.

[0004]

By the way, in the conventional shift control method, there is a delay in the rise of the hydraulic pressure supplied to the friction engagement element at the time of power-on upshift and a variation in the friction coefficient of the friction plate of the friction engagement element. As shown by the broken line in FIG. 1, the engagement start delay of the engagement side frictional engagement element may occur. In such a case, if the disengagement of the frictional engagement element on the disengagement side is completely released, the engine speed may exceed the maximum allowable speed (upper limit) determined by the design specifications and overshoot may occur. The engine speed temporarily jumps into the so-called red zone, and the engine speed overshoot amount varies.

The present invention has been made in order to solve such a problem. Even when the durability of the friction engagement element is deteriorated or the rising of the supplied hydraulic pressure is delayed, the engine speed can be stably maintained. An object of the present invention is to provide a shift control method for an automatic transmission for a vehicle, in which overshoot is suppressed to a value equal to or lower than an allowable maximum number of revolutions so that a feeling of shift is not uncomfortable.

[0006]

In order to achieve such an object, according to the present invention, a first friction engagement element and a high speed side, each of which is hydraulically driven and establishes a low speed side shift speed. A second friction engagement element that establishes a shift speed,
While the first friction engagement element is disengaged during an upshift, the second friction engagement element is supplied to the second friction engagement element after being stroked by a predetermined invalid stroke section. A shift control method for an automatic transmission for a vehicle, which increases the hydraulic pressure at a predetermined increase rate, waits for the actual shift start, starts feedback shift control after the actual shift starts, and reduces the input shaft rotation speed toward the synchronous rotation speed. In, the elapsed time from the reference time point before the actual shift start point to the actual shift start point is measured, and the measured elapsed time is compared with a predetermined determination value,
A shift control method for an automatic transmission for a vehicle, comprising increasing the increase rate of the hydraulic pressure supplied to the second friction engagement element and waiting for the actual shift start when the elapsed time is larger than a predetermined determination value. Provided.

[0007]

In the shift control method of the present invention, referring to FIG. 1, the actual shift start point Ns is changed from the reference time point, for example, the shift command time point or the hydraulic pressure start point of the second (coupling side) friction engagement element.
The elapsed time t up to is measured. This actual shift start point Ns
Is the point at which the handheld transmission torque is switched to the coupling side frictional engagement element, the shaft torque is restored, and gear shifting is actually started, and the input shaft rotation speed starts to decrease. More specifically, the so-called torque phase shift starts at the same time when the engagement by the coupling side frictional engagement element starts, the transmission torque of the coupling side frictional engagement element increases, and the input shaft rotational speed changes to the above-mentioned actual shift. Starting point N
When s is reached, so-called inertia phase shift starts.
In this inertia phase shift, it means a state in which the transmission torque of the coupling side friction engagement element should be feedback-controlled, and for example, the input shaft rotation speed is synchronized so that the input shaft rotation speed change rate matches the target change rate. Decrease towards speed of rotation.

Therefore, by comparing the elapsed time measured as described above with a predetermined determination value, it is possible to determine whether or not the input shaft rotation speed exceeds the allowable maximum rotation speed and overshoots. When the time is larger than the predetermined determination value, the increase rate of the hydraulic pressure supplied to the coupling side friction engagement element is increased to accelerate the increase of the transmission torque of the coupling side friction engagement element, thereby reaching the actual shift start point. The time required for is shortened.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 shows a schematic configuration of an automatic transmission of an automobile that implements the shift control method according to the present invention. Reference numeral 1 in the figure indicates an internal combustion engine, and the output of the engine 1 is transmitted to drive wheels (not shown) via an automatic transmission 2. The automatic transmission 2 includes a torque converter 4, a gear transmission 3, a hydraulic circuit 5, a controller 40 and the like. The gear transmission 3 has, for example, four forward gears and one reverse gear.
It is provided with a gear shift stage and a friction engagement element of a hydraulic clutch or a hydraulic brake that performs a shift operation by switching the shift position. The hydraulic circuit 5 has a duty solenoid valve (hereinafter simply referred to as a solenoid valve) corresponding to each of the friction engagement elements described above, and each friction engagement element, that is,
Operate each clutch and brake independently of each other. Each solenoid valve is electrically connected to the output side of a controller (ECU) 40, which will be described later, and adjusts the hydraulic pressure supplied to the friction engagement element by a drive signal from the ECU 40.

FIG. 3 is a partial block diagram of the gear transmission 3. A first drive gear 31 and a second drive gear 32 are rotatably arranged around the input shaft 3a. In addition, the input shaft 3a between the first drive gear 31 and the second drive gear 32,
Hydraulic clutches 33 and 34 are fixedly installed as speed change friction engagement elements. The drive gears 31 and 32 rotate integrally with the input shaft 3a by engaging the clutches 33 and 34, respectively.

The intermediate transmission shaft 35 arranged in parallel with the input shaft 3a is connected to the drive axle via a final reduction gear unit (not shown). A first driven gear 36 and a second driven gear 37 are fixedly mounted on the intermediate transmission shaft 35, and these driven gears 36 and 37 mesh with the drive gears 31 and 32, respectively. Therefore, when the clutch 33 and the first drive gear 31 are engaged, the rotation of the input shaft 3a is changed by the clutch 33, the first drive gear 31, the first driven gear 36, and the intermediate transmission shaft 35. And the first speed (for example, the second speed) is achieved.
Further, when the clutch 34 and the second drive gear 32 are engaged, the rotation of the input shaft 3a is the same as the clutch 34, the second
Drive gear 32, second driven gear 37, intermediate transmission shaft 3
And the second speed (for example, the third speed) is achieved.

From the state in which the clutch 33 on the second speed side is engaged, the clutch 33 is disengaged while the third gear is engaged.
By engaging the clutch 34 on the high speed side, the automatic transmission 2
Shifts up from second gear to third gear. Conversely, by engaging the clutch 33 while releasing the engagement of the clutch 34 from the state in which the clutch 34 is engaged,
The automatic transmission 2 shifts down from the third speed to the second speed.

The above-mentioned clutches 33 and 34 are, for example,
A hydraulic multi-plate clutch is used.
3 shows an example. The clutch 33 includes a large number of friction engagement plates 5
When hydraulic oil is supplied to the clutch 33 from the oil passage 14 through the port 51, the piston 52 moves forward to frictionally engage the friction engagement plates 50. On the other hand, when the piston 52 returns while being pressed by the return spring 53 to discharge the hydraulic oil to the oil passage 14 via the port 51, the friction engagement between the friction engagement plates 50 is released. The clutch 34 is also configured similarly to the clutch 33.

The ECU 40 has a built-in storage device such as ROM and RAM, a central processing unit, an input / output device, a counter (all not shown) and the like. On the input side of the ECU 40, various sensors, for example, a turbine rotation speed sensor (Nt sensor) 21 for detecting the rotation speed Nt of the input shaft of the gear transmission 3, that is, the turbine of the torque converter 4, a transfer drive (not shown). No sensor 2 for detecting the gear rotation speed (output shaft rotation speed of the gear transmission 3) No
2, it is arranged in the intake passage (not shown) of the engine 1,
As a parameter value representing the engine load, a throttle valve opening sensor (θt
Sensor) 23, Ne for detecting the rotation speed Ne of the engine 1
The sensor 24 and the like are electrically connected. Each of these sensors 21 to 24 supplies a detection signal to the ECU 40. Note that the ECU 40 can calculate the vehicle speed based on the rotation speed No of the transfer drive gear detected by the No sensor 22.

Next, the shift control at the time of upshifting executed by the ECU 40 will be described by taking as an example the case of shifting up from the first gear to the second gear. FIG. 5 shows the ECU 40.
Shows a schematic procedure of an upshift transmission control which is executed when an upshift from the first gear to the second gear is discriminated.
First, in step S10, the ECU 40 sets the duty ratio of the solenoid valve on the release side to 0 until the transmission torque of the clutch 33 that has established the first gear becomes substantially 0.
Is set to release the hydraulic pressure supplied to the clutch 33, while the duty ratio of the solenoid valve of the clutch 34 that establishes the second speed is set to 100%, and the clutch 34 starts engaging from its standby position. Stroke the invalid stroke section to the position immediately before. That is, the holding transmission torque of the disengagement side clutch 33 and the coupling side clutch 34 is switched.

When the coupling side clutch 34 has finished the stroke in the invalid stroke section (when the so-called rattling operation is completed), the ECU 40 proceeds to step S12 and sets the duty ratio Da of the coupling side solenoid valve 34 to the predetermined value Dao. Then, the solenoid valve 34 is driven at the set duty ratio Da. This predetermined value Dao is, for example, the coupling side clutch 3
The stroke position of No. 4 is set to a value which holds the above-mentioned position immediately before the start of coupling experimentally or by learning at each shift control.

Next, the ECU 40 detects the turbine rotation speed Nt detected by the Nt sensor 21 (step S1).
4) It is determined whether or not the detected turbine rotation speed Nt has become a value lower than the first rotation speed by a predetermined rotation speed ΔN1 (for example, 20 rpm), that is, whether out-of-synchronization is detected (step). S16). Immediately after the rattling operation described above is completed, out-of-synchronization is not normally detected, so the determination result in step S16 is negative (No).
Then, the process proceeds to step S18.

In step S18, the duty ratio Da of the coupling side solenoid valve is set to a value obtained by adding a predetermined increment ΔDao to the previous value Da, and the coupling side solenoid valve is driven with this value. Then, the process returns to step S14 again, and the duty ratio Da of the coupling side solenoid valve is increased at a predetermined increase rate while repeating the detection of out-of-synchronization, so that the hydraulic pressure supplied to the coupling side clutch 34 is also increased by the predetermined increase rate α. (See FIG. 1) and wait until out-of-sync is detected. The above-described predetermined increment ΔDao is set to a value by an over-rotation monitoring routine described later.

When the oil pressure supplied to the coupling side clutch 34 is gradually increased and out of synchronization is detected, the determination result of step S16 becomes affirmative (Yes), and the routine proceeds to step S20 to start the feedback shift control. The feedback shift control method is not particularly limited, but various known methods can be applied.
The supply hydraulic pressure of the coupling clutch 34, that is, the transmission torque is feedback-controlled so that the time change rate of the turbine rotation speed Nt matches the target change rate.
Decrease t toward the second speed synchronous speed.

Next, in step S22, it is determined whether or not the turbine rotation speed Nt has substantially reached the second speed synchronous rotation speed, more specifically, the absolute value of the deviation between the turbine rotation speed Nt and the second speed synchronous rotation speed is It is determined whether or not it has become equal to or less than a predetermined determination value ΔN2 (for example, 50 rpm). If the determination result is negative, step S20 is repeatedly executed to continue the feedback shift control.

When the second speed synchronization is detected and the result of the determination in step S20 is affirmative, the process proceeds to step S24, in which the hydraulic pressure of the clutch 33 on the disengagement side is completely released, while the solenoid valve of the clutch 34 on the engagement side is released. The duty ratio Da is 10
Set to 0% to fully engage clutch 34. In this way, the shift up from the first gear to the second gear is completed.

FIG. 6 shows an overspeed monitoring routine in which the above-described increment ΔDao is corrected as follows. The ECU 40 executes this routine every time the upshift gear shift control is executed, and first, in step S30, it is determined whether or not the hydraulic pressure supply to the coupling side clutch 34 is started. The time point at which the supply of the hydraulic pressure to the clutch 34 is started serves as a reference for measuring an elapsed time described later. The ECU 40, after the upshift gear shift command is output, passes the coupling side clutch 34 at the time when an invalid time until the hydraulic pressure is actually supplied to the clutch 34 elapses.
It is considered that the hydraulic pressure supply of has started.

If the hydraulic pressure supply to the coupling side clutch 34 is not started in step S30, step S30 is repeatedly executed to wait until the hydraulic pressure supply is started.
When the supply of the hydraulic pressure to the clutch 34 is started, the process proceeds to step S32, the timer is started, and the elapsed time from the hydraulic pressure supply start time of the coupling clutch 34, which is the reference time, is started to be measured.

Next, in step S34, it is determined whether or not the actual shift start point Ns has been detected. The Ns point means the shift start point of the inertia phase, but in reality, the ECU
Reference numeral 40 compares the previous value and the current value of the input shaft rotation speed Nt, and when the current value is lower than the previous value, that is, when the input shaft rotation speed Nt after the gear shift command starts to decrease for the first time. When it is detected, it is regarded as an Ns point and detected. If the determination result of step S34 is negative, Ns
Wait until the point is detected.

When the Ns point is detected in step S34, the elapsed time Tst is read from the above-mentioned timer (step S36), and the read elapsed time Tst is compared with a predetermined reference time XST (step S38). The timer is reset after reading the elapsed time Tst. The reference time XST is an allowable upper limit time from the aforementioned reference time point to the inertia phase shift start point, and the time required to reach the inertia phase shift start point is the allowable upper limit time XST.
If it is larger, it means that the engine rotation speed Ne exceeds the maximum permissible rotation speed (upper limit value) and the overshoot amount becomes large as shown by the broken line in FIG. Therefore, when the determination result of step S38 is negative, the routine is ended without doing anything, but when the determination result is affirmative, the minute value Δd is added to the increment ΔDao described above, and this is incremented to a new increment. Store as ΔDao (step S4)
0).

As described above, every time the shift control is executed once, the elapsed time Tst required from the reference time point to the shift start point of the inertia phase is monitored, and the increment ΔDao is corrected according to the elapsed time Tst. The corrected increment ΔDao increases the rate of increase in the hydraulic pressure supplied to the coupling side clutch 34 after the rattling operation is greater than that in the previous shift control.

In the above embodiment, the reference time point for starting the timer is the hydraulic pressure supply start time point for the coupling side clutch, but instead of this, the time point when the shift command is output may be used as the reference time point. Further, although the point at which the input shaft rotational speed starts to decrease is detected as the actual shift start point Ns, the point at which the engine speed Ne starts to decrease (see FIG. 1).
(Ne, Ne2 points in the middle) may be detected and used as the Ns point.

The hydraulic circuit of the above embodiment is provided with a solenoid valve for each friction engagement element (clutch, brake) on the coupling side and the release side, and is supplied to each friction engagement element by the corresponding solenoid valve. The operating hydraulic pressure is controlled. The shift control method of the present invention is not limited to the automatic transmission having the hydraulic circuit of this configuration. Figure 7
Shows a second aspect of the hydraulic circuit to which the method of the present invention is applied, which hydraulic fluid supplies the working hydraulic pressure to the coupling-side and disengagement-side frictional engagement elements 28, 30 to one solenoid valve 6.
The thing controlled by 7 is illustrated. The construction of the hydraulic circuit for controlling the operating hydraulic pressures of the coupling side and disengagement side friction engagement elements by one solenoid valve is disclosed in JP-A-58-46.
Similar ones are already known from JP-A No. 258, JP-A-60-215143 and the like.

The operation of the kick-down brake 30 for establishing the second speed is controlled by a kick-down servo 80 as a reciprocating hydraulic actuator, and the kick-down servo 80 and a housing defining a stepped cylinder hole 80c. , A stepped piston 80e slidably fitted in the stepped cylinder hole 80c, and this piston 80
a piston rod extending from e to the outside of the housing,
That is, the actuator rod 80f is configured to be provided, and the tip of the actuator rod 80f is
The kick-down brake 30, that is, the brake shoe wound around the peripheral surface of the kick-down drum 52, can be brought into contact with and engaged with the brake shoe. Then, the piston 80e has the first and second pressure chambers 80a, 8a in the stepped cylinder hole 80c.
The first pressure chamber 80a is defined between the step surface of the piston 80e and the step surface of the stepped cylinder hole 80c, as is clear from FIG.

Then, the 2-3 shift valve 5 is connected to the first pressure chamber 80a of the kick-down servo 80 through the oil passage 65.
5 is connected, and the 2-3 shift valve 55 is further connected to a shift control valve 69 via an oil passage 62. An oil passage 83 is branched from the middle of the oil passage 65, and this oil passage 83 is connected to the 1-2 shift valve 84. The 1-2 shift valve 84 is further connected to bifurcated oil passages 85 and 86, and one of these two oil passages 85 is provided with a kick-down servo 80.
Is connected to the second pressure chamber 80b, and the other oil passage 86 is connected to the front clutch 28 that establishes the first gear. Note that the front clutch 28 is shown only schematically in FIG. 7.

Here, the 2-3 shift valve 55 and the 1-2 shift valve 84 are spool type on-off valves that are opened and closed by the pressure supplied to the operation control ports 87 and 88, and also the operation control ports. The pressure to 87 and 88 is specifically introduced from a switching valve (not shown). For example, in the third gear, the 2-3 shift valve 5
Unlike the case shown in FIG. 7, the spool 55a of No. 5 does not receive the switching pressure through its operation control port 87, and is in the state of being displaced to the left end. Therefore, in this case, the oil passage 65 is connected to the oil discharge port EX of the 2-3 shift valve 55.
The kickdown servo 80
The first pressure chamber 80a is connected to the low pressure side.
As a result, the piston 80e of the kickdown servo 80
7 is returned to the right in FIG. 7 by the spring force of the compression coil spring 80d in the second pressure chamber 80c, and the kickdown brake 30 is disengaged from the kickdown drum 52. Further, at this time, the switching pressure is not supplied to the 1-2 shift valve 84 through the operation control port 88, so that the spool 84a of the shift valve 84 of FIG.
Inside, it is in the state of being displaced to the left end as shown. Therefore, in this case, the oil passage 86 leading to the front clutch 28 is 1
-2 is in the state of being connected to the low pressure side through the oil discharge port 90 of the shift valve 84, which allows the front clutch 2
The engagement of 8 is released. In this case, the oil passage 85,
Since 86 is always in communication, the second pressure chamber 80c in the kickdown servo 80 is also connected to the low pressure side.

Also, in the second speed, the 2-3 shift valve 55 is switched to the illustrated switching position,
The 1-2 shift valve 84 is also switched to the position shown. Therefore, in this case, when the pressure liquid is supplied to the first pressure chamber 80a of the kick down servo 80 through the oil passages 62 and 65, the piston 80e, that is, the actuator rod 80f, moves leftward and kicks. The down brake 30 is engaged, whereas the pressure liquid in the front clutch 28 can be discharged through the oil passage 86 and the oil discharge port 90, whereby the engagement of the front clutch 28 is released. ..

Further, in the first gear, the 2-3 shift valve 55 remains in the switching position shown in the figure, while the 1-2 shift valve 84 has its spool to the right. The oil passage 83 and the oil passages 85 and 86 are communicated with each other through the 1-2 shift valve 84, and the oil discharge port 90 is closed. In this case, through the 2-3 shift valve 55, the oil passage 83
The pressure fluid supplied to the front clutch 28 is supplied to the front clutch 28 via the 1-2 shift valve 84 and the oil passage 86, whereby the front clutch 28 reaches the engaged state. On the other hand, in the kick down servo 80, since the oil passages 86 and 85 are always in communication with each other,
The pressure liquid supplied to the front clutch 28 is also supplied to the second pressure chamber 80b thereof, and at the same time, the same pressure liquid is supplied to the first pressure chamber 80a through the oil passage 65. .. In this case, the piston 80e of the kick-down servo 80 is a stepped piston as described above, and therefore the piston 80e is
Displaced to the right with the actuator rod 80f,
As a result, the engagement of the kick down brake 30 is released.

Further, when the shift stage is shifted from the 1st speed to the 2nd speed, the 2-3 shift valve 55 and the 1-2 shift valve 84 are respectively in the switching positions shown in the drawing.
Regarding the kick-down servo 80, the first pressure chamber 8
By supplying the pressurized liquid to 0a, the piston 80e,
That is, the actuator rod 80f is displaced in the direction in which the kick-down brake 30 is engaged, while the actuator rod 80f moves from the front clutch 28 to the oil passage 86 and the 1-2 shift valve 8.
4 is released through the oil discharge port 90 and the oil discharge port 90, the engagement is released. At this time, the engagement of the front clutch 28 is released by the piston 80e of the kick-down servo 80 as described later. Is displaced by the back pressure generated in the second pressure chamber 80b.

Therefore, in order to generate an appropriate back pressure in the second pressure chamber 80b, the drain port 90 of the 1-2 shift valve 84 is provided with a predetermined throttle 91, and
-A predetermined throttle 9 is also provided in the oil passage 84 guided to the -2 shift valve 84.
Two are provided. Then, the shift control valve 69 described above
7, the oil passage 61 is connected to the left end of the oil passage, and the oil passage 63 is connected to the oil passage. The oil passage 61 is connected to an oil pump, and in the middle of the oil passage 61, a solenoid valve 67 that opens and closes the oil passage 61 and controls the pressure of the hydraulic fluid supplied through the shift control valve 69.
Has been inserted. The solenoid valve 67 is electrically connected to an electronic control unit (ECU) 40, and the electronic control unit 40 controls the switching operation of the solenoid valve 67 by duty control. Also, in the oil passage 63,
The operating oil pressure adjusted to a predetermined pressure is supplied from the above-mentioned oil pump. The hydraulic fluid in the oil passage 61 is discharged to the low pressure side via the solenoid valve 67 that is opened / closed according to the duty ratio, so that the hydraulic pressure according to the duty ratio acts on the left end surface of the spool 69a of the shift control valve 69. Will be done. As a result, the shift control valve 69 regulates the hydraulic pressure from the oil passage 63 to generate a predetermined hydraulic pressure PKD in the oil passage 62.

Then, the ECU 40 is supplied with the detection signal of the driving state of the vehicle from the same various sensors as shown in FIG. 2, and the same shift control as described above is executed to execute the above-mentioned 1-
Two upshifts are performed. In the case of the second mode, when the supply of the operating hydraulic pressure to the kickdown servo 80 on the coupling side is started, the duty ratio of the solenoid valve 67 is gradually changed to set the pressing force of the kickdown brake 30 to a predetermined value. Wait for out-of-sync by increasing at an increasing rate. Then
When out-of-synchronization is detected, the turbine rotation speed Nt is monitored, and the duty ratio of the solenoid valve 67 is feedback-controlled so that its change rate matches the target speed. In the second embodiment, the increase rate of the pressing force of the kickdown brake 30 is increased according to the elapsed time Tst detected in the overspeed monitoring routine to wait for the loss of synchronization (start of actual gear shift). Become.

[0037]

As described above, according to the method of the present invention, the elapsed time from the reference time point before the actual shift start point to the actual shift start point is measured, and the measured elapsed time is compared with the predetermined determination value. However, when the elapsed time is larger than the predetermined determination value, the increase rate of the hydraulic pressure supplied to the second friction engagement element (coupling clutch) is increased to wait for the actual shift start. The generation of the transmission torque or the rising of the supplied hydraulic pressure is accelerated, the shift start point of the inertia phase is reached sooner, and the over-rotation of the engine is prevented. The overspeed monitoring routine of the present invention operates as a backup of normal gear shift control, and operates effectively when, for example, the friction coefficient of the clutch or brake decreases due to deterioration of durability, and the overshoot amount becomes large. The shift control can be eliminated, and the maximum engine speed at the time of shifting can be stably suppressed below the maximum allowable engine speed. Further, according to the present invention,
Since the shift control for increasing the increase rate of the supplied hydraulic pressure is a control until the inertia phase starts, it does not affect the inertia phase, and therefore, even if this control is activated, the shift feeling does not feel uncomfortable. Further, since the above-mentioned increase rate of the hydraulic pressure is corrected during one shift control, it is possible to instantaneously deal with the disturbance during the shift.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship of changes over time of an input shaft rotation speed, a coupling side clutch supply pressure, an engine rotation speed, and a shaft torque of an automatic transmission that is shift-controlled by the method of the present invention.

FIG. 2 is a schematic configuration diagram of an automatic transmission for a vehicle to which the method according to the present invention is applied.

FIG. 3 is a schematic configuration diagram showing a part of a gear train of the gear transmission 3 of FIG.

FIG. 4 is a cross-sectional view showing the hydraulic clutch of FIG.

FIG. 5 is a flowchart showing a shift control procedure at the time of upshifting according to the method of the present invention.

FIG. 6 is a flowchart of an overspeed monitoring routine.

FIG. 7 is a hydraulic circuit diagram showing a second mode of the hydraulic circuit of the automatic transmission to which the method of the present invention is applied.

[Explanation of symbols]

 1 Engine 2 Automatic Transmission 3 Gear Transmission 5 Hydraulic Circuit 22 Transfer Drive Gear Speed Sensor 23 Throttle Valve Opening Sensor 24 Engine Speed Ne Sensor 28 Friction Engagement Element (Clutch) 30 Friction Engagement Element (Brake) 33 Friction Engaging element (clutch) 34 Friction engaging element (clutch) 40 Controller

Claims (1)

[Claims] 1. A first frictional engagement element each of which is hydraulically driven to establish a low speed side shift speed and a second frictional engagement element for establishing a high speed side shift speed, and which has the first frictional engagement element during an upshift. The second frictional engagement element is disengaged while the second
After the frictional engagement element is stroked by the predetermined invalid stroke section, the hydraulic pressure supplied to the second frictional engagement element is increased at a predetermined increase rate to wait for the actual shift start, and the feedback after the actual shift start is performed. In a shift control method for an automatic transmission for a vehicle, in which shift control is started to decelerate an input shaft rotation speed toward a synchronous rotation speed, an elapsed time from a reference time point before the actual shift start point to an actual shift start point is calculated. The measured elapsed time is compared with a predetermined determination value, and when the elapsed time is greater than the predetermined determination value, the increase rate of the hydraulic pressure supplied to the second friction engagement element is increased to start the actual shift. A shift control method for an automatic transmission for a vehicle, characterized by waiting.