JP2738202B2 - Shift control method for automatic transmission for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an automatic transmission for a vehicle,
The present invention relates to a shift control method when switching from the neutral range (N) to the drive register (D).

[0002]

2. Description of the Related Art An automatic transmission mounted on an automobile is provided with a number of frictional engagement means such as a hydraulic multi-plate clutch and a hydraulic brake, and by changing the combination of frictional engagement means to be engaged, A shift change has been implemented. For example, when the driving mode is temporarily changed to the N range and then changed to the D range again while the vehicle is running, the controller that controls the automatic transmission determines that the shift speed suitable for running is, for example, the third speed. Is selected, the controller abruptly engages the first frictional engagement means (this is referred to as an OD (overdrive) clutch) of the automatic transmission, and sets the second frictional engagement means (this UD
(Under drive) clutch is gradually engaged, and a shift change from neutral to third speed is performed.

Each of the clutches transmits torque by frictionally engaging a number of friction engagement plates with each other. A predetermined clearance is provided between the friction engagement plates to prevent a large drag torque from being generated between the friction engagement plates when the clutch is completely disengaged. For this reason, a so-called rattling operation for moving the invalid stroke is required between the start of supplying the hydraulic pressure to each clutch and the start of actual frictional engagement between the friction engagement plates. The time required for this rattling operation is obtained in advance by experiments, but often differs between the clutches due to variations in manufacturing accuracy and the like, and changes due to wear of the friction engagement plates and the like. .

[0004] The controller stores in advance each rattling time obtained in an experiment for each clutch, and further stores
By performing so-called learning control, these play-out times are appropriately updated. Then, after performing the rattling operation of each clutch based on the rattling time, the controller subsequently starts the engagement of each clutch, and moves the automatic transmission from the N range to the D range as described above. The shift is changed to 3rd gear.

[0005]

By the way, when performing a shift change of an automatic transmission, in order to reduce a shift shock, it is necessary to engage a clutch (an OD clutch in the above-mentioned case) on the side to be rapidly engaged. It is desirable that the engagement be completed before the engagement of the clutch that is gradually engaged (UD clutch in the above case) is completed.

However, the loosening time of each clutch is different, so that the UD clutch may end the loosening operation earlier than the OD clutch, and the engagement of the UD clutch may be started earlier. . In such a case, there is a possibility that a shift shock of the automatic transmission may occur, causing a problem that the shift feeling is inferior. SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a shift control for reducing a shift shock of an automatic transmission in which two or more friction engagement means are engaged to establish one shift stage. The aim is to provide a method.

[0007]

According to the present invention, there is provided an automatic transmission for a vehicle in which at least first and second frictional engagement means are engaged in order to establish one shift speed. In the speed change control method of the machine, the first frictional engagement means is moved from the standby position where the engagement is completely released to the position immediately before the engagement is started, and thereafter, the first frictional engagement means is moved. While the first frictional engagement means is suddenly engaged, the second frictional engagement means moves an invalid stroke from a standby position where the engagement is completely released to a position immediately before the engagement is started. After that, the second frictional engagement means is gradually engaged subsequently, and the movement of the invalid stroke of the first frictional engagement means is completed at least when the movement of the invalid stroke of the second frictional engagement means is completed. To complete by Shift control method of dual automatic transmission is provided.

[0008]

The first and second frictional engagement means move the invalid stroke to complete the so-called rattling operation, and thereafter, these engagement operations are started. Since the first frictional engagement means completes the movement of the invalid stroke before the second frictional engagement means, when the first frictional engagement means completes the movement of the invalid stroke, the second engagement means It is still in the disengaged state and does not generate transmission torque. For this reason, even if the second frictional engagement means has already started engaging when the first frictional engagement means completes the movement of the invalid stroke, there is no possibility that a shift shock will occur.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of an automatic transmission for a vehicle that implements a shift control method according to the present invention. Reference numeral 1 in the figure denotes an internal combustion engine, and the output of the engine 1 is transmitted to driving 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 traveling range of the automatic transmission 2 is controlled by a driver operating a shift lever (not shown). To be selected. This shift lever is provided in the driver's seat. As shown in FIG. 2, the gear transmission 3 is composed of a power train using a plurality of planetary gear mechanisms, a shift friction engagement unit for operating each shift speed, and the like. This speed change friction engagement means includes first to third clutches 33 to 35, first and second brakes 36, 37, and the like. Of these, the combination of operating clutches and brakes is changed. As a result, a shift change is performed. That is, Table 1
When the respective clutches and brakes are operated in accordance with the combinations shown in (1), the corresponding gears are established.

[0011]

[Table 1] Here, in the table, C is the clutch, B is the brake, Re
v means reverse, N means neutral, and P means parking. In the table, ○ indicates operation.

For example, when only the first clutch 33 and the first brake 36 are engaged, the first speed is established, and the first clutch 33 and the second clutch 36 are engaged.
When only the clutch 34 is engaged, the third speed is established. FIG. 3 shows a cross section of the first clutch 33, which has a number of friction engagement plates 50. When hydraulic oil is supplied into the first clutch 33 from the oil passage 14 to be described later via the port 51, the piston 52 moves forward to frictionally engage the friction engagement plates 50. On the other hand, being pressed by the return spring 53,
When the piston 52 moves backward while discharging the hydraulic oil into the oil passage 14 via the port 51, the friction engagement between the friction engagement plates 50 is released.

When completely disengaging the first clutch 33, each friction engagement plate 50 is made to wait at the standby position. In this standby position, between the friction engagement plates 50,
Sufficient clearance is provided to prevent the generation of drag torque. For this reason, when the first clutch 33 is engaged, first, the above-mentioned clearance is set to substantially zero.
In other words, it is necessary to perform a so-called rattling operation in which each friction engagement plate 50 is moved by an invalid stroke to a position where the friction engagement occurs.

The second and third clutches 34, 35
The first clutch 33 differs from the first clutch 33 in the time required for the backpacking operation, that is, the backpacking time, but they have the same configuration. Therefore, the description and illustration of the second and third clutches 34 and 35 are omitted. Also, as the first and second brakes 36 and 37, conventional ones are used, and even when these brakes are engaged, the invalid stroke from the standby position to the position immediately before the start of frictional engagement is reduced. Moving is still the same.

Each of the shift friction engagement means is provided with a hydraulic circuit 5
It is operated by a duty solenoid valve (hereinafter, simply referred to as a solenoid valve) provided in the power supply. That is, the hydraulic circuit 5 includes the clutches 33 to 35 and the brakes 36, 3
7, one solenoid valve is provided corresponding to each of
These operate independently of each other. In addition, since each solenoid valve operates each clutch 33-35 and each brake 36, 37 similarly, the solenoid valve 11 which operates the first clutch 33 will be described with reference to FIG.
Description of the other solenoid valves that operate the clutches 34 and 35 and the brakes 36 and 37 will be omitted.

FIG. 4 shows a part of the hydraulic circuit 5, which is provided with a solenoid valve 11 capable of supplying a hydraulic pressure to the first clutch 33. The solenoid valve 11 is a normally closed two-position switching valve and has ports 11a to 11c at three locations. The first port 11a is connected to a first oil passage 13 extending to an oil pump (not shown). This first oil passage 13
A control valve, a pressure regulating valve, and the like (not shown) are interposed in the middle of the vehicle, and according to the traveling range selected by the shift lever,
An operating oil pressure (line pressure) adjusted to a predetermined pressure is supplied.

A second oil passage 14 extending to the first clutch 33 is provided at the second port 11b.
Are connected to third oil passages 15 extending to an oil tank (not shown). These second and third oil passages 1
Apertures 16 and 17 are provided in the middle of 4 and 15, respectively. The flow passage area of the throttle 16 provided in the second oil passage 14 is set larger than the flow passage area of the throttle 17 provided in the third oil passage 15. Further, the first clutch 3
An accumulator 18 is connected in the second oil passage 14 between the throttle 3 and the throttle 16.

The solenoid valve 11 is electrically connected to a controller 40, and the duty ratio is controlled by the controller 40 at a predetermined cycle, for example, at a control cycle of 50 Hz. When the solenoid 11e of the solenoid valve 11 is deenergized, the valve body 11f is pressed by the return spring 11g and the first port 11a is pressed.
And the second port 11b, while the solenoid 11e
Is biased, the valve element 11f lifts up against the spring force of the return spring 11g, and connects the first port 11a and the second port 11b. Note that the second port 11b and the third port 11c are always in communication.

The controller 40 includes a ROM (not shown),
A storage device such as a RAM, a central processing unit, an input / output device, a counter and the like are built in. Various sensors, for example, an Nt sensor 21, a No sensor 22, and a θt sensor 23 are electrically connected to the input side of the controller 40. The Nt sensor 21 is a turbine rotation speed sensor that detects the rotation speed Nt of the turbine of the torque converter 4. The No sensor 22 is a transfer drive gear rotation speed sensor that detects the rotation speed No of a transfer drive gear (not shown). The controller 40 can determine the vehicle speed V based on the rotation speed No. The θt sensor 23 is a throttle valve opening sensor that detects a valve opening θt of a throttle valve arranged in the middle of an intake passage (not shown) of the engine 1. Each of these sensors 21 to 23 supplies a detection signal to the controller 40 every predetermined time period.

The controller 40 is controlled according to the traveling range selected by the shift lever and the traveling state of the vehicle.
According to the program stored in the storage device, the automatic transmission 2
Carry out a shift change. That is, the controller 4
0 continuously monitors the travel range selected by the shift lever and the signals from the Nt sensor 21, No sensor 22, θt sensor 23, etc., and determines whether or not to execute the shift change of the automatic transmission based on these information. to decide.

For example, a case will be described in which the automatic transmission is shifted from neutral to third speed. The mode of this shift change is such that when the shift lever is selected to the N range during driving of the vehicle and then the shift lever is again selected to the D range, the speed suitable for driving the vehicle is the third speed. This is realized when the controller 40 determines.

In this case, the disengaged first and second clutches 33 and 34 are engaged (see Table 1). In this case, the controller 40 suddenly engages the second clutch 34 while the first clutch 33
Is gradually engaged to reduce shift shock. FIG.
Shows an operation procedure when the first and second clutches 33 and 34 are engaged.

First, the controller 40 determines in step S6
At 0, the loosening times T1 and T2 of the first clutch 33 and the second clutch 34 are read. Note that the backlash times T1 and T2 are obtained through experiments and the like, and are stored in the storage device of the controller 40 in advance. These values are appropriately updated to optimal values by the controller 40 performing so-called learning control.

Next, the controller 40 proceeds to step S6.
The program proceeds to 1 and compares the loosening time T1 of the first clutch 33 with the sum of the loosening time T2 of the second clutch 34 and the allowance time Tm. Here, the allowance time Tm is equal to the second clutch 3
4 is set to a small value in consideration of the variation of the invalid stroke time and the aging. Then, the condition T1 ≧ T2 +
If Tm is satisfied, the controller 40 proceeds to step S
Proceed to 62. In this case, the loosening time T2 is sufficiently shorter than the loosening time T1, and even if the loosening operations of the first clutch 33 and the second clutch 34 are started simultaneously, the second clutch The loosening operation of 34 is completed before the loosening operation of the first clutch 33 (FIG. 6).

Therefore, in step S62, the controller 40 sets the second clutch 34 and the first clutch 33
Are simultaneously driven at a duty ratio of 100% (time point a in FIG. 6). As a result, the loosening operations of the clutches 33 and 34 are started at the same time, and as shown in FIG. 6, the hydraulic pressures of the clutches 33 and 34 gradually increase.

Then, the controller 40 determines in step S
Proceeding to 63, it is determined whether or not the time from the start of the stuffing operation has reached the stuffing time T1.
This step S63 is repeatedly executed until elapses. At this time, for the second clutch 34, when the elapsed time from the point a reaches the time T2 (point b in FIG. 6).
Then, the play operation is completed. Accordingly, as shown in FIG. 6, thereafter, the hydraulic pressure of the second clutch 34 sharply increases, and the second clutch 34 is rapidly engaged.

When the time T1 elapses in this step S63 (time c in FIG. 6), the first clutch 33
When the loose filling operation is completed, the controller 40 exits step S63 and proceeds to step S64. Step S6
4, the controller 40 controls the first clutch 33
The solenoid valve 11 is driven at a predetermined initial duty ratio Da to start feedback control. In this feedback control, in order to synchronize the input shaft rotation speed Nt with the rotation speed on the output shaft side, a predetermined control law, for example, the input shaft rotation speed change rate (Nt) ′ is changed to the target rotation speed change rate (N
The operation hydraulic pressure supplied to the first clutch 33 is feedback-controlled so as to coincide with i) ′, whereby the input shaft rotation speed Nt changes toward the synchronous rotation speed.

Then, the step S65 is repeatedly executed, and the feedback control is continued to the first clutch 33.
And gradually wait until the rotation speed Nt reaches the synchronous rotation speed. Then, when the synchronization is completed, the feedback control is also completed, and the controller 40 exits step S65 and proceeds to step S66. In step S66, the controller 40 drives the solenoid valve 11 that operates the first clutch 33 at a duty ratio of 100% (at a point d in FIG. 6). Thus, the first clutch 33 is maintained in the engaged state, and the third speed is established.

As described above, the controller 40 can complete the engagement of the first clutch 34 after the engagement of the second clutch 34 is completed, and the automatic transmission 2 is smoothly shifted to the third speed. You. On the other hand, if the condition T1 ≧ T2 + Tm is not satisfied in step S61, the process proceeds to step S70. In this case, the loosening time T1 is shorter than the loosening time T2, and the second loosening time T1 is earlier than the loosening operation of the first clutch 33.
In order to complete the loosening operation of the clutch 34, it is necessary to delay the start time of the loosening operation of the first clutch 33 (FIG. 7).

In step S70, the controller 4
In the case of 0, the solenoid valve for operating the second clutch 34 is driven at a duty ratio of 100% (time f in FIG. 7), and first, the loosening operation of the second clutch 34 is started. Then, in step S71, the time T1 is divided from the sum of the time T2 and the time Tm to obtain ΔT, and then, in step S72, the lapse of ΔT is determined. Until the time ΔT elapses, no backlash operation is performed on the first clutch 33.

In step S72, when ΔT has elapsed, the controller 40 proceeds to step S73, in which the solenoid valve 11 for operating the first clutch 33 is driven at a duty ratio of 100%, and the loosening operation of the first clutch 33 is performed. Start (time point g in the figure). As a result, the first and second
The clutches 33 and 34 are both backlashed.

After step S73, the controller 40 proceeds to step S63 described above, and continues the loosening operation of the first clutch 33 until the time T1 has elapsed from the point of time g. At this time, with respect to the second clutch 34, the rattling operation is completed when the time T2 has elapsed from the point f in the drawing (point h in the drawing). And after that,
As shown in the figure, the hydraulic pressure of the second clutch 34 rapidly rises,
The second clutch 34 is suddenly engaged.

On the other hand, in step S63 of FIG.
When the time T1 elapses from the time (time k in FIG. 7), the first time
The loosening operation of the clutch 33 is completed. Subsequently to this, the controller 40 executes step S64 and subsequent steps and gradually engages the first clutch 33, as in the case described above. When the first clutch 33 is completely engaged (at point p in FIG. 7), the controller 40 sets the solenoid valve 1
1 at a duty ratio of 100%.
Is maintained in the engaged state. Thereby, the automatic transmission 2 is smoothly shifted, and the third speed is established.

In this embodiment, the automatic transmission 2
Has been described from the neutral to the third speed in the D range, but the present invention is not limited to this mode. If it is necessary to engage three or more engagement means to establish one shift speed, the friction engagement means used for controlling the input shaft rotation speed Nt as described above is used. That is, leaving the friction engagement means to gradually engage after moving the invalid stroke,
The other friction engagement means may complete the movement of the invalid stroke by the time the movement of the invalid stroke of the friction engagement means to be gradually engaged is completed.

[0035]

As described above, according to the present invention,
Since the shift control of the automatic transmission for a vehicle is performed by the above-described method, the shift shock is reduced, the shift feeling can be improved, and the shift response can be improved. There is.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of an automatic transmission for a vehicle in which a method according to the present invention is implemented.

FIG. 2 is a schematic configuration diagram of the gear transmission shown in FIG. 1;

FIG. 3 is a sectional view showing the clutch shown in FIG. 2;

FIG. 4 is a schematic configuration diagram showing a part of a hydraulic circuit that operates the clutch shown in FIGS. 2 and 3;

FIG. 5 is a flowchart showing an operation procedure of first and second clutches to be engaged when the automatic transmission shown in FIG. 1 is shifted from neutral to third speed.

FIG. 6 illustrates a case where a condition of step S61 in FIG. 5 is satisfied.
FIG. 5 is a diagram illustrating a relationship between a change in hydraulic pressure of each clutch and a change in duty ratio of each solenoid valve.

FIG. 7 is a diagram showing a relationship between a change in hydraulic pressure of each clutch and a change in duty ratio of each solenoid valve when the condition of step S61 in FIG. 5 is not satisfied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Gear transmission 5 Hydraulic circuit 11 Solenoid valve 13-15 Oil passage 33-35 Clutch 36,37 Brake 40 Controller

Claims (1)

(57) [Claims] 1. A shift control method for an automatic transmission for a vehicle in which at least first and second frictional engagement means are engaged to establish one shift speed, wherein the first frictional engagement means is engaged. Is moved from the standby position in which is completely released to the position immediately before the start of engagement, and then the first frictional engagement means is suddenly engaged, while the second stroke is engaged. Friction engagement means,
After moving the invalid stroke from the standby position where the engagement is completely released to the position immediately before the engagement starts,
Subsequently, the second frictional engagement means is gradually engaged, and the movement of the invalid stroke of the first frictional engagement means,
A shift control method for an automatic transmission for a vehicle, wherein the shift is completed at least until the movement of the invalid stroke of the second frictional engagement means is completed.