JP3030353B2 - Shift control method for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed to engage a friction engagement element on an engagement side while waiting for the rotation of the engine to decrease while slightly slipping the friction engagement element which is opened during an upshift. The present invention relates to a shift control method for an automatic transmission.

[0002]

2. Description of the Related Art An automatic transmission using a planetary gear mechanism is composed of a plurality of sets of planetary gear units and a plurality of rotating units constituting the planetary gear units on a transmission input shaft connected to a crankshaft of an engine via a torque converter. A plurality of friction engagement elements that respectively restrain the elements are incorporated, and a combination of the engagement states of the friction engagement elements is switched via hydraulic pressure to achieve a desired shift speed.

In this case, in order to independently control the supply hydraulic pressure to the plurality of frictional engagement elements, a plurality of hydraulic control valves, each of which is duty-controlled, are incorporated in each frictional engagement element and electronically controlled. The transmission is JP-A-63-
It is proposed in Japanese Patent Publication No. 298350.

[0004] As shown in FIG. 4, which shows the concept of a power transmission mechanism in a front-wheel drive type vehicle equipped with such an automatic transmission having four forward speeds and one reverse speed, it is connected to a crankshaft of an engine (not shown). A pump 14 formed integrally with the input case 13 of the torque converter 12 is connected to the drive shaft 11. A turbine 15 of the torque converter 12 facing the pump 14 is connected to an overdrive clutch 17 and an underdrive clutch 18 and a reverse clutch 19 which are friction engagement elements via a transmission input shaft 16.
The stator 20 of the torque converter 12 located between the turbine 15 and the pump 14 is connected to a transmission case 22 via a one-way clutch 21.

The output side of the overdrive clutch 17 is connected via a connecting shaft 23 to a carrier 25 of a first planetary gear set (hereinafter simply referred to as a first planetary set) 24 and a second planetary gear set (hereinafter referred to as a first planetary gear set). , This is called the second planetary device)
The carrier 27 is connected to a low reverse brake 28 for stopping the rotation of the connecting shaft 23. The output side of the under drive clutch 18 is connected to the sun gear 29 of the first planetary gear 24, and the output side of the reverse clutch 19 is connected to the intermediate cylinder 30.
Through the internal gear 31 of the first planetary device 24,
The sun gear 32 of the second planetary device 26 and a 2-4 brake 33 for stopping the rotation of the intermediate cylinder 30 are connected.

The first planetary device 24 includes the sun gear 29 and the planetary gears 3 meshing with the sun gear 29.
4, the carrier 25 rotatably supporting the planetary gear 34 and rotatably held with respect to the transmission case 22, and the above-described internal gear 31 meshing with the planetary gear 34, constitute a main part. .
Further, the second planetary device 26 includes the sun gear 32 described above,
The planetary gear 35 meshes with the sun gear 32, the carrier 27 rotatably supports the planetary gear 35 and is rotatably supported with respect to the transmission case 22, and the internal gear 36 meshes with the planetary gear 35. The internal gear 36 is connected to a hollow transmission output shaft 37 through which the connecting shaft 23 passes.

An output gear 38 formed on the transmission output shaft 37 has a driven gear 40 of a drive transmission shaft 39 disposed in the transmission case 22 substantially parallel to the transmission input shaft 16 as an idle gear 41. The drive transmission shaft 39 has a front differential 4
2 and a final reduction gear 44 connected to the left and right drive axles 43.

The clutches 17 to 19 and the brakes 28 and 33 functioning as frictional engagement elements with the rotating elements of the first planetary device 24 and the second planetary device 26 include a piston device or a servo device (not shown). The engagement and disengagement of these components is performed by supplying and discharging pressure oil to and from the motor. The pressure oil is selectively supplied to each of the clutches 17 to 19 and the brakes 28 and 33 by a hydraulic control device (not shown). Is achieved.

As shown in FIG. 5 showing the relationship between the combination of the engagement states of these friction engagement elements and the respective gears, a circle in the figure represents the engagement state of the corresponding friction engagement element. The mark indicates the open state of the corresponding friction engagement element.

For example, when the low reverse brake 28 and the underdrive clutch 18 are engaged, the rotation of the carrier 25 of the first planetary device 24 and the carrier 27 of the second planetary device 26 are restricted. , Drive shaft 11
From the torque converter 12, the transmission input shaft 1
6, the underdrive clutch 18, the sun gear 29 of the first planetary device 24, the planetary gear 34, the internal gear 31, the sun gear 32 of the second planetary device 26, the planetary gear 35, and the transmission output shaft 3 via the internal gear 36.
The transmission is transmitted to the right and left drive axles 43 via the output gear 38, the drive transmission shaft 39, and the final reduction gear 44.

Next, when the low-reverse brake 28 is released and the 2-4 brake 33 is engaged while the engaged state of the underdrive clutch 18 is maintained, the internal gear 31 of the first planetary gear 24 and The rotation of the sun gear 32 of the second planetary device 26 is restricted, and the driving force from the drive shaft 11 is applied to the sun gear 29 and the carrier 25 of the first planetary device, the carrier 27 of the second planetary device 26, the internal gear 36,
The power is transmitted to the output gear 38 via the transmission output shaft 37, and the second speed is achieved.

When the 2-4 brake 33 is released and the overdrive clutch 17 is engaged while the engaged state of the underdrive clutch 18 is maintained, the sun gear 29 of the first planetary device 24 and the carrier 25 are integrated. As a result, the entire first planetary gear 24 rotates integrally. As a result, the sun gear 32 and the carrier 27 of the second planetary device 26 rotate integrally, and the entire second planetary device 26 also rotates integrally. As a result, the transmission input shaft 16 and the output gear 3
Thus, the third speed is established in which the number of rotations is the same as that of the third speed.

Further, when the underdrive clutch 18 is released and the 2-4 brake 33 is engaged while maintaining the engagement state of the overdrive clutch 17, the sun gear 32 of the second planetary device 26 is fixed, and Axis 1
1 is transmitted to the output gear 38 via the connecting shaft 23, the sun gear 32 of the second planetary gear 26, the planetary gear 35, the carrier 27, and the transmission output shaft 37, and the rotation of the output gear 38 is input to the transmission. A fourth speed is achieved, which is faster than the rotation of the shaft 16.

On the other hand, the overdrive clutches 17 and 2
When the reverse clutch 19 and the low reverse brake 28 are disengaged and the low reverse brake 28 is disengaged, the carrier 27 of the second planetary gear 26 is fixed, and the driving force from the drive shaft 11 is , An output gear 38 via a sun gear 32, a planetary gear 35, an internal gear 36, and a transmission output shaft 37 of the second planetary device 26.
And the reverse gear is achieved.

As shown in FIGS. 6 to 8 showing the schematic structure of a hydraulic control circuit for achieving each of the shift speeds shown in FIG. 5, the hydraulic control circuit of the above-mentioned automatic transmission includes an oil pan 45 and a filter. The pressure oil sucked up by the oil pump 47 is supplied to the torque converter 12 via 46, and this pressure oil is supplied to the clutches 17 to 19 and the piston devices or servo devices (not shown) of the brakes 28 and 33, etc. In order to selectively supply or withdraw the frictional engagement elements in accordance with the conditions.

The hydraulic control circuit includes a pressure regulating valve 48 for adjusting the oil pressure of the pressure oil from the oil pump 47 to a predetermined desired value (hereinafter referred to as a line pressure); Converter control valve 49 for controlling the supply / discharge of the vehicle, a P position used for parking, an R position for reverse driving, an N position for stopping, and a first speed- A D4 position at which an automatic shift can be performed between the fourth speeds,
D3 position where automatic shifting is possible between first to third speeds, 2 position where automatic shifting is possible between first and second speeds, and first position A manual valve 50 that operates in accordance with an L position fixed to a shift stage;
9 and four electromagnetic switching valves 51 to 54 for switching supply and discharge of pressure oil to and from the brakes 28 and 33, and a line pressure switching valve 5 for switching the line pressure to an optimum value for each shift speed.
5 and when a certain forward gear is achieved, one or more of the four electromagnetic switching valves 51 to 54 malfunction and three or more friction engagement elements are simultaneously engaged. A pair of safety valves for preventing the rotation of the transmission output shaft 37 from being restrained and forcibly shifting to any of the second to fourth gears so that the vehicle can run. 56,
A main part is constituted by 57 and these components are mutually connected via an oil passage.

When the driver operates the change lever (not shown) to select one of the forward gears D4, D3, 2, L, the change lever is formed on the spool 58 of the manual valve 50. The notch 59 moves to the position D shown in the figure, and a forward movement corresponding to the position of the change lever and the driving state of the vehicle is performed by a combination of ON / OFF of energization of the four electromagnetic switching valves 51 to 54 whose energization amount is duty-controlled. Is achieved. When the change lever is set to the position P or N, the spool 5
The 8 notch 59 moves to the illustrated NP position, and the neutral state is achieved. Furthermore, the change lever is R
Is selected, the notch 59 of the spool 58
Position to allow the automatic transmission to achieve the reverse gear.

Each of the four electromagnetic switching valves 51 to 54 is a three-way valve that operates in response to an electric signal from an electronic control unit (not shown). Communicate with each other. In addition, the second electromagnetic switching valve 52 is a closed type when not energized,
Other first, third, and fourth electromagnetic switching valves 51, 5
3 and 54 are all of the open type when not energized.
The relationship between each gear position of the automatic transmission and the on / off state of power supply to these four electromagnetic switching valves 51 to 54 is shown in FIG.
As shown in FIG. 9 , the-mark in the figure indicates that it may be either on or off. Also, in FIG.
Is between the underdrive clutch 18 and the electromagnetic switching valve 53
The accumulator provided in FIG.
Is operated by switching the valve 103.
Between the switch 28 and the electromagnetic switching valve 51 or 2-4 brake 3
Accu which will be located between
In FIG. 8, reference numeral 104 denotes a valve
The reverse clutch 19 and the electromagnetic switching valve 51
Or the overdrive clutch 17 and the electromagnetic switching valve 54
The accumulator will be located between.

The oil drain 61 is also connected to the manual valve 50 and a pair of safety valves 56 and 57.

The first electromagnetic switching valve 51 and the low reverse clutch 28
The first safety valve 56 is interposed between the oil passages 62 and 63 for supplying and discharging pressurized oil to and from the oil passages. Similarly, the second electromagnetic switching valve 52 and the 2-4 brake 33 are connected via oil passages 64 and 65 for supplying and discharging pressure oil to and from the 2-4 brake 33. The second safety valve 57 is interposed between the oil passages 64 and 65.

The third electromagnetic switching valve 53 and the underdrive clutch 18 are connected to the underdrive clutch 18.
Similarly, the fourth electromagnetic switching valve 54 and the overdrive clutch 17 are connected to each other via an oil passage 66 for supplying and discharging pressure oil to and from the overdrive clutch 17.
Are connected via an oil passage 67 for supplying and discharging pressure oil.

Further, the reverse clutch 19 and the manual valve 50 are connected via an oil passage 68 for supplying and discharging pressure oil to and from the reverse clutch 19.

Therefore, when the change lever (not shown) is set at the position N or notch, the notch 59 formed on the spool 58 of the manual valve 50 also moves to the position PN shown. The pressure oil discharged from the oil pump 47 when the engine is started is supplied from the oil passage 69 to the pressure regulating valve 48 and the manual valve 50, while the oil pressure is discharged through the oil passage 70 branched from the oil passage 69. The control oil is also guided to the control valve 49, and pressure oil of a predetermined pressure is supplied to the torque converter 12 through an oil passage 71 connecting the torque converter control valve 49 and the torque converter 12. Further, the pressure oil supplied to the manual valve 50 is supplied to the manual valve 50 and the line pressure switching valve 5.
The oil is supplied to the line pressure switching valve 55 via an oil passage 72 connecting the oil pressure 5 to the line 5, and is also pressure-fed to a pair of all-zero valves 56 and 57 via an oil passage 73 branched from the oil passage 72. In this state, all of the four electromagnetic switching valves 51 to 54 are kept in a non-energized state.

Here, when the driver operates the change lever to select the position D4, the notch 59 of the manual valve 50 moves to the position D shown in the drawing, and the pressure oil from the oil passage 69 is supplied to the three electromagnetic switching valves. The check valve 75 is also supplied to oil passages 74 connected to the respective oil passages 52 to 54 and further communicates with the oil passages 74.
Is supplied to the first solenoid-operated directional control valve 51.

Here, in order to engage the low reverse brake 28 and the underdrive clutch 18 to achieve the first speed, only the fourth electromagnetic switching valve 54 is energized by an electronic control unit (not shown). The first and third electromagnetic switching valves 51 and 53 are opened to connect the oil passage 74 to an oil passage 62 connecting the first electromagnetic switching valve 51 and the first safety valve 56.
And the oil passage 74 is connected to the third electromagnetic switching valve 53.
And an oil path 66 connecting the underdrive clutch 18 with the oil passage 66.

Thus, the pressure oil guided to the oil passage 62 is guided to the low reverse brake 28 via an oil passage 63 connecting the first safety valve 56 and the low reverse brake 28. The pressure oil guided to the oil passage 66 is guided to the underdrive clutch 18, and as a result, the low reverse brake 28 and the underdrive clutch 18 are engaged to achieve the first speed.

Next, when an upshift to the second speed is instructed by the electronic control unit based on the running state of the vehicle, the first, second, and fourth electromagnetic switching valves 51, 52,
By energizing 54, the first electromagnetic switching valve 51 and the oil passage 74 are closed, and the oil passage 62 communicates with the oil discharge passage 61, so that the pressure oil supplied to the low reverse brake 28 is discharged. The oil is discharged from the oil passage 63 through the oil discharge passage 61 through the oil passage 62 through the first safety valve 56, and the low reverse brake 28 is released.

As described above, since the second electromagnetic switching valve 52 also switches from the non-energized state to the energized state, the oil passage 74 is connected to the second electromagnetic switching valve 52 and the second safety valve. And an oil passage 64 connecting the oil passage 57 to the oil passage 57. Thereby, the pressure oil guided from the oil passage 74 to the oil passage 64 via the second electromagnetic switching valve 52 is supplied to the second safety valve 57 and the 2-4 brake 33.
And is led to the 2-4 brake 33 via the oil passage 65 connecting the 2 and 3 and the 2-4 brake 33 is engaged.

Since the third electromagnetic switching valve 53 is kept in the non-energized state, the oil passage 74 and the oil passage 66 communicate with each other in the same manner as in the case of the first speed change stage. Drive clutch 18 is held in the engaged state. Further, since the fourth electromagnetic switching valve 54 is maintained in the energized state, the fourth electromagnetic switching valve 54 and the overdrive clutch 17
And the oil passage 67 connecting the oil discharge passage 61 and
As a result of the overdrive clutch 17 being kept in the disengaged state, the second speed is achieved.

Next, the electronic control unit changes the speed from the second speed to the third speed.
When an upshift to a higher gear is instructed, only the first solenoid-operated directional control valve 51 is energized, so that the first safety valve 56 operates via the oil passage 63 as in the case of the second gear. The oil passage 62 communicating with the low / reverse brake 28 communicates with the oil discharge passage 61, and the low / reverse brake 28 maintains the open state. Similarly, since the third electromagnetic switching valve 53 is kept in a non-energized state, the oil passage 66 connected to the underdrive clutch 18 and the oil passage 7 to which the line pressure is supplied are provided.
4 and the underdrive clutch 1
8 remain engaged.

Since the second electromagnetic switching valve 52 is switched to the non-energized state, the oil passage 64 communicating with the 2-4 brake 33 via the oil passage 65 by the second safety valve 57 is connected to the oil discharge passage 6.
1 and 2-4 brake 33 will be in a release state. Similarly, since the fourth electromagnetic switching valve 54 switches to the non-energized state, the oil passage 67 connected to the overdrive clutch 17
As a result, the line pressure is guided to the overdrive clutch 17 and the overdrive clutch 17 shifts to the engaged state, so that the third speed is achieved.

Further, when a shift from the third speed to the fourth speed is instructed by an electronic control unit (not shown), the first to third electromagnetic control valves 51 to 53 are turned on. At the same time, the fourth electromagnetic control valve 54 is turned off. Here, the energization state of the first electromagnetic control valve 51 does not change similarly to the third speed, so that the low reverse brake 28 is connected to the first electromagnetic valve 63 from the oil passage 63 and the first safety valve 56 via the oil passage 62. The control valve 51 is in communication with the oil discharge passage 61, and the low reverse brake 28 is kept open. Similarly, the fourth solenoid-operated directional control valve 54 is also kept in the non-energized state as in the case of the third speed, and the line pressure from the oil passage 74 is supplied to the overdrive clutch 17 via the oil passage 67. Therefore, the overdrive clutch 17 is held in the engaged state.

On the other hand, since the second electromagnetic control valve 52 switches from the non-energized state to the energized state, the oil passage 74 communicates with the oil passage 64 and the line pressure from the oil passage 74 is reduced by the oil passage 64 and the second passage. 2-4 brake 33 from oil passage 65 via safety valve 57
As a result, the 2-4 brake 33 is switched to the engaged state. Similarly, the third electromagnetic control valve 53 is also switched from the non-energized state to the energized state, the communication state between the oil passage 74 and the oil passage 66 is released, and the oil discharge passage 61 and the oil passage 66 communicate with each other. As a result of the pressure oil of the drive clutch 18 being discharged to the oil discharge port 60 side via the oil passage 66, the underdrive clutch 18 is switched to the disengaged state, and the fourth speed is achieved.

When a change lever (not shown) is selected to the position of D3, 2, or L, the shift range corresponding to the position of the change lever is determined only by a command from the electronic control unit. Notch 5 of valve 50
Reference numeral 9 is maintained at the position D shown in FIG. 6, and there is no change in the flow of the pressure oil.

When the driver selects the selector lever to the R position, the notch 5 provided on the spool 58 of the manual valve 50
9 also moves to the R position, the oil passage 69 connected to the oil pump 47 communicates with the oil passage 68 connecting the reverse clutch 19 and the manual valve 50, and the reverse clutch 19 is engaged.

Here, the first electromagnetic control valve 51 is in a non-energized state, but an oil passage 74 that can be connected to the first electromagnetic control valve 51 via the check valve 75 is connected to the manual valve 50. The line is in communication with the connected oil discharge passage 61, and the line pressure is not supplied from the oil passage 74 to the first electromagnetic control valve 51.
However, since the check valve 75 is also connected to the oil passage 68, the line pressure from the oil passage 68 is supplied to the low reverse clutch 28 via the oil passage 62, the first safety valve 56, and the oil passage 63. As a result, the low reverse brake 28 is also engaged, and the reverse gear is achieved.

When the selector lever is set to a position other than the R position, the oil passage 68 communicating with the reverse clutch 19 is in communication with the oil passage 76 provided in the manual valve 50 and connected to the oil discharge passage 61. Therefore, the pressure oil of the reverse clutch 19 is discharged from the oil passage 68 to the oil discharge port 60 via the oil passage 76 via the oil passage 76 incorporated in the manual valve 50, and the reverse clutch 19 is released. Has become.

By the way, in such an automatic transmission, when engaging the friction engagement element on the engagement side while waiting for the rotation of the engine to decrease while slightly sliding the friction engagement element which is opened at the time of the upshift. When the slip amount of the release-side friction engagement element is equal to or greater than a predetermined threshold, the switching valve that controls the supply oil pressure to the release-side friction engagement element is operated to control the release-side friction engagement element. While increasing the supply oil pressure, when the rate of change of the slip amount of the frictional engagement element on the release side is 0 or less, the switching valve is reversely operated to decrease the supply oil pressure for the frictional engagement element on the release side. U.S. Pat. No. 3,956,947 proposes a configuration in which the drive torque is smoothly shifted from the frictional engagement element on the coupling side to the frictional engagement element on the coupling side.

That is, the slip amount of the frictional element on the open side during the upshift, the ON / OFF state of the electromagnetic switching valve for controlling the hydraulic pressure for the frictional element on the open side, As shown in FIG. 10 showing the relationship with the supply hydraulic pressure for the friction engagement element, when the slip amount of the release-side friction engagement element exceeds, for example, 20 rpm, the supply hydraulic pressure for the release-side friction engagement element is controlled. When the change rate of the slip amount of the open-side frictional engagement element is 0 or less, the solenoid-operated solenoid-operated valve is turned off. Thus, the supply hydraulic pressure to the frictional engagement element on the open side is reduced.

In this manner, while the frictional engagement element which is opened during the upshift is slightly slipped, the engagement of the frictional engagement element on the engagement side is smoothly performed after waiting for the rotation of the engine to be reduced, so that the shift shock is prevented. The occurrence is prevented beforehand.

[0041]

FIG. 10 shows a state in which the frictional engagement element on the engagement side is engaged while waiting for the rotation of the engine to decrease while slightly slipping the frictional engagement element that is opened during an upshift. In the case of the conventional micro slip control shown in
If the driving torque associated with the slippage of the release-side frictional engagement element is too large or too small, a shift shock is likely to occur.

For example, in FIG. 10, when the electromagnetic switching valve is turned on and the supply oil pressure to the open-side frictional engagement element rises sharply, the rate of change of the slip amount of the open-side frictional engagement element is reduced. Even if it becomes 0 or less and the electromagnetic switching valve is operated to 0FF, the supply oil pressure to the frictional engagement element on the open side becomes too high. As a result, the frictional engagement element on the release side is completely engaged and the drive torque sharply increases, and a large shift shock may occur when the frictional engagement element on the engagement side is engaged.

For this reason, in performing the above-described minute slip control, it is very important to reduce the fluctuation of the slip amount of the frictional engagement element on the opening side in order to prevent the occurrence of the shift shock. Become.

[0044]

An object of the present invention is to provide a method for engaging the frictional engagement element on the engagement side while waiting for the rotation of the engine to drop while slightly slipping the frictional engagement element which is released during an upshift. It is an object of the present invention to provide a shift control method in which a shift shock is hardly generated by performing a smoother shift operation in an automatic transmission in which a hydraulic pressure for a friction engagement element is controlled.

[0045]

SUMMARY OF THE INVENTION A shift control method for an automatic transmission according to the present invention is characterized in that during an upshift, the frictional engagement element on the open side is slightly slipped while waiting for the rotation of the engine to decrease, and the frictional engagement on the engagement side is performed. When engaging the elements, if the slip amount of the release-side friction engagement element is equal to or greater than a predetermined threshold, the switching valve that controls the supply hydraulic pressure to the release-side friction engagement element is operated to perform the release. While the supply oil pressure to the frictional engagement element on the side is increased, when the change rate of the slip amount of the frictional engagement element on the open side is 0 or less, the switching valve is operated in reverse to operate the frictional engagement on the open side. In the automatic transmission configured to reduce the supply hydraulic pressure to the element, if the slip amount of the release-side friction engagement element is equal to or more than a first threshold, the switching valve is continuously turned on to perform the slip operation. The amount is above the first threshold Small, and if greater than said smaller second threshold than the first threshold, ON of the switching valve,
The OFF operation is intermittently operated to suppress an increase in hydraulic pressure with respect to the frictional engagement element on the release side.

[0046]

When the slip amount of the frictional engagement element on the release side is equal to or less than the second threshold value , the switching valve is operated in the reverse direction, and
The supply oil pressure for the frictional engagement element on the release side gradually decreases.

The slip amount of the frictional engagement element on the release side is the first
If the value is smaller than the threshold value and larger than the second threshold value , the switching valve is intermittently operated to suppress a rapid increase in hydraulic pressure with respect to the frictional engagement element on the open side, and the frictional engagement element on the release side is excessively engaged. Not to be.

The slip amount of the frictional engagement element on the open side is first
If it is larger than the threshold value , the switching valve is operated to reliably reduce the hydraulic pressure supplied to the frictional element on the open side, thereby reducing the slip amount.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a shift control method for an automatic transmission according to the present invention is applied to an automatic transmission having four forward speeds and one reverse speed shown in FIGS. 4 to 9 will be described below.

[0050] In the present embodiment, the slip amount N _S of the friction engagement elements of the open side of the upshift and the rotational speed N _T of the turbine 15 of the torque converter 12 transmission output shaft 37
Is calculated based on the rotation speed N _{0 of}
Specifically, the value is obtained by subtracting the product of the rotation speed N ₀ of the transmission output shaft 37 and the transmission gear ratio i before the shift from the rotation speed _NT of the turbine 15 of the torque converter 12. N _S = N _T −N ₀ × i

[0051] Then, so as to control the hydraulic pressure for the friction engagement element in an open state based on the slip amount N _S of the friction engagement elements of the open side and its rate of change alpha.
When Specifically, the state slippage N _S frictional engagement element on the open side is not too large, for example, the slip amount N _S of the friction engagement elements of the open side is between 70rpm from 20 rpm,
In this embodiment, if the ON state of the electromagnetic switching valve is continuously determined within two control cycles so that the ON determination state of the electromagnetic switching valve does not continue for a long time, in the next one control cycle, The solenoid-operated directional control valve is kept in the OFF state to mitigate an increase in the open side hydraulic pressure.

When the slip amount N _S of the frictional engagement element on the release side is large, for example, 70 rpm or more, it is meaningless to perform the minute slip control. Do not adopt.

As shown in FIG. 1 showing the flow of the shift control method for an automatic transmission according to the present invention, when an upshift shift command is issued at M1, frictional engagement on the engagement side is performed at M2. The engagement hydraulic pressure for the frictional engagement element on the open side is released while the engagement hydraulic pressure for the
Slip amount N _S of the friction engagement elements of the open side at the -20rpm
It is determined whether it is less than.

[0054] slippage N _S of the friction engagement elements of the open side at this M3 in step is not less than -20Rpm, i.e. occurrence of speed change shock upon rotational speed is still too high, and upshifting of the turbine 15 of the torque converter 12 if it is determined that a possibility exists that, whether now slip amount N _S of the friction engagement elements of the opening side exceeds the 20rpm at M4, and the rate of change of the slip amount N _S alpha is positive judge.

[0055] slippage N _S of the friction engagement elements of the open side at the step of the M4 exceeds the 20 rpm, yet is positive change rate α of the slip amount N _S, i.e. increased significantly slip amount N _S is if it is determined that there is a tendency to perform a minute slip control of the present invention that fall within the certain range of slip amount N _S of the friction engagement elements of the open side at M5, returns to M3 step.

[0056] Similarly, the slip amount N _S of the friction engagement elements of the open side at M4 in step is not more than 20 rpm, yet the rate of change in the slip amount N _S alpha is less than or equal to zero, i.e. the slip amount N If it is determined that there is almost no _{S and} there is a decreasing tendency, the process returns to the step of M3.

[0057] The slip amount N _S of the friction engagement elements of the open side at the M3 in step is less than -20Rpm, i.e. torque converter 12 along with the engagement of the frictional engagement element on the engagement side
When it is determined that the speed change shock has hardly occurred even if the upshift operation is performed because the rotation speed of the turbine 15 of FIG. , The actual shift start control of M6 is performed to complete the predetermined upshift operation.

As shown in FIG. 2 showing the flow of the process of the micro slip control in the above-mentioned step M5, first, S
At step 1, the control counter number I is set to 0, and then at step S2, the control counter number I is incremented by one. And S3
It is determined whether or not the control counter number I is 2 or less. In the case of the processing flow from the beginning, it is determined that the control counter number I is 2 or less, and that the slip amount N _S of the disengagement side frictional engagement element tends to increase in step M4. since it is, the electromagnetic switching valve to launch an engagement oil pressure for the frictional engagement element on the open side to the ON state at S4, the slip amount N _S of the friction engagement elements of the open side is controlled to be reduced.

From this state, it is determined in S5 whether or not 6.7 milliseconds, which is the control cycle of the present embodiment, has elapsed.
The rate of change α is negative slip amount N _S of the friction engagement elements of the open side at the in S6 when the milliseconds have elapsed, or slippage N _S of the friction engagement elements of the open side whether less than 20rpm judge.

[0060] slippage N _S frictional engagement element if the change rate of the slip amount N _S of the friction engagement elements of the open side at this step S6 α is negative, or the open side is less than 20 rpm,
That is, the slip amount N _{S of the} open-side frictional engagement element is decreasing or the slip amount N _{S of the} open-side frictional engagement element is decreasing.
If it is determined that there is almost no _{S, the} solenoid-operated directional control valve is turned off in S7 in order to reduce the engagement hydraulic pressure for the frictional engagement element on the release side, and the process returns to the step M3 shown in FIG. slip amount N _S frictional engagement element on the open side by the driving force waits for the increase again.

[0061] or the change rate of the slip amount N _S of the friction engagement elements of the open side at the step of the S6 alpha is 0 or more, or slip amount N _S frictional engagement element on the open side is not less than 20 rpm, i.e. or slip amount N _S frictional engagement element on the open side is increasing, or when it is determined that the slip amount N _S of the friction engagement elements of certain open side, the control returns to S2 in step The counter number I is incremented by one. Then, the process shifts from the step S3 to the step S4 again, and the solenoid-operated directional control valve is again operated to raise the release hydraulic pressure.
And ON state, the slip amount N _S of the friction engagement elements of the open side is controlled to be reduced.

In step S3, the control counter number I
If but it becomes 3 or more, determines whether the slip amount N _S frictional engagement element on the open side of 70 or more rotations at S8. When the slip amount N _S of the friction engagement elements of the open side at this step S7 is 70 or more turns, i.e. the slip amount N _S of the friction engagement elements of the open side is determined to too large, S9 after resetting the control counter number I to 0 in, and the oN state of the electromagnetic selector valve to launch the open side hydraulic proceeds to step S4, the slip amount N _S frictional engagement element on the open side is reduced Control.

[0063] Further, the slip amount N _S of the friction engagement elements of the open side at the step S7 is less than 70 rotates, that is, when the slip amount N _S of the friction engagement elements of the open side is determined to be moderate In step S10, the electromagnetic switching valve is turned off in order to reduce the engagement hydraulic pressure with respect to the frictional engagement element on the open side, and the control counter number I is reset to 0 in step S11. Then, the process proceeds to step S5.

[0064] In this manner, when the slip amount N _S of the friction engagement elements of the open side is between 70rpm from 20 rpm, if the ON state of the open side hydraulic pressure is followed two successive control cycle In the next one control cycle, the release-side hydraulic pressure is kept in the OFF state, and a sudden rise in the release-side hydraulic pressure is reduced. And the slip amount N _S of the friction engagement elements of the open side of the case, ON the electromagnetic switching valve corresponding to the friction engagement element of the open side, Figure represents the OFF state, the relationship between its open side hydraulic 3 As shown in (1), the rise of the oil pressure becomes slower than in the conventional method, and no adverse effect such as a shift shock due to excessive engagement of the frictional engagement element on the open side occurs.

[0065] However, when the slip amount N _S of the friction engagement elements of the open side exceeds the 70rpm keeps the ON state regardless any electromagnetic switching valve in the control period to launch the open side hydraulic, open slip amount N _S of the friction engagement elements of the side are 70r
Control to decrease to pm or less.

[0066]

According to the hydraulic control method for an automatic transmission of the present invention, when the slip amount of the frictional engagement element on the release side is not so large as to exceed the threshold value, the switching valve is intermittently operated in reverse to open. The increase in the hydraulic pressure applied to the frictional engagement element on the side is suppressed, so that it is possible to avoid a problem in which the frictional engagement element on the open side is completely engaged, and a smooth upshift without a shift shock. Operations can be performed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of a shift control method for an automatic transmission according to the present invention, together with FIG.

FIG. 2 is a flowchart showing an embodiment of a shift control method for an automatic transmission according to the present invention, together with FIG.

FIG. 3 shows the relationship between the amount of slip rotation of the frictional engagement element on the open side, the ON / OFF state of the electromagnetic switching valve corresponding to the frictional engagement element on the open side, and the hydraulic pressure on the release side according to the method of the present invention. It is a graph showing.

FIG. 4 is a conceptual view of a mechanism showing an example of a schematic structure of an automatic transmission to which the present invention is applied.

FIG. 5 is an operation element diagram showing a relationship between a combination of engagement states of the friction engagement elements and each shift speed.

6 is a hydraulic control circuit diagram showing a part of the hydraulic control circuit together with FIGS. 7 and 8. FIG.

FIG. 7 is a hydraulic control circuit diagram showing a part of the hydraulic control circuit together with FIG. 6 and FIG.

8 is a hydraulic control circuit diagram showing a part of the hydraulic control circuit together with FIGS. 6 and 7. FIG.

FIG. 9 is an operation element diagram showing a relationship between energized states of the four electromagnetic control valves and each shift speed.

FIG. 10 shows the slip rotation amount of the frictional engagement element on the release side and the electromagnetic switching valve corresponding to the frictional engagement element on the release side.
5 is a graph showing a relationship between an ON / OFF state and a hydraulic pressure on an open side thereof.

[Explanation of symbols]

12 is a torque converter, 16 is a transmission input shaft, 17 is an overdrive clutch, 18 is an underdrive clutch, 19 is a reverse clutch, 21 is a one-way clutch,
23 is a connecting shaft, 24 is a first planetary gear, 26 is a second planetary gear, 28 is a low reverse brake, 30 is an intermediate cylinder, 3
3 is a 2-4 brake, 37 is a transmission output shaft, 39 is a drive transmission shaft, 42 is a front differential, 43 is a drive axle, 47 is an oil pump, 48 is a pressure regulating valve, 49 is a torque converter control valve, and 50 is manual. valves, 51-54 electromagnetic switching valve 55 the line pressure switching valve, 56 and 57 safety valve, 60 is the drain oil port 61 oil discharge passage, 62-74 are oil passage 75 check valve, N _S is The slip amount of the release-side friction engagement element, α is the rate of change of the slip amount of the release-side friction engagement element, and I is the number of control counters.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shigeyuki Yoshida 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (56) References JP-A-62-246653 (JP, A)

Claims (1)

(57) [Claims] When the engagement of the engagement side frictional engagement element is performed while waiting for the rotation of the engine to be reduced while slightly causing the release side frictional engagement element to slip during the upshift, the release side frictional engagement element is engaged. When the slip amount is equal to or greater than a predetermined threshold value, the switching valve for controlling the supply oil pressure to the release-side friction engagement element is operated to increase the supply oil pressure to the release-side friction engagement element. In the automatic transmission, when the change rate of the slip amount of the friction engagement element on the side is less than or equal to 0, the switching valve is operated in reverse to decrease the supply hydraulic pressure to the friction engagement element on the open side. When the slip amount of the frictional engagement element on the release side is equal to or more than the first threshold,
When the switching valve is continuously turned on and the slip amount is smaller than the first threshold value and larger than a second threshold value smaller than the first threshold value, ON / OF of the switching valve is performed.
A shift control method for an automatic transmission, wherein an F operation is intermittently operated to suppress an increase in hydraulic pressure with respect to the frictional engagement element on the release side.