JPH09133205A - Shift controller in automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out smooth shift without carrying out closed loop control in a clutch-to-clutch power on/down shift. SOLUTION: A means, which determines both a first period after the shift judgment and a second period after the first period elapsed, and a controlling means, which controls the oil pressure on the high-speed stage side and on the low-speed stage side, are provided. In the first control, the transferred torque capacity of a high-speed side frictional stage side engaging element is lowered during the first period down to a value at which the output shaft torque is not negative, while, in the second control, the transferred torque capacity of the high speed stage side frictional engaging element is raised within the second period (after the elapse of the first period) up to the value that is equivalent to the input shaft torque in order to appropriately control the torque capacity of the low speed stage side frictional engaging element. After the elapse of the second period, the transferred torque capacity of the low speed stage side frictional engaging element is raised exceeding the input shaft torque and carrying out the third control releasing the high speed stage side frictional engaging device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch-to-clutch power-on downshift (release of power from an engine side to a wheel side) by releasing a high-speed stage side friction engagement element and engaging a low-speed stage side friction engagement element. The present invention relates to a shift control device for an automatic transmission that performs a downshift that is performed while being performed.

[0002]

2. Description of the Related Art When executing a specific gear shift of an automatic transmission, for example, a high gear clutch (high speed gear side friction engagement element) is released and a low gear clutch (low speed gear side friction engagement element) is engaged. It is often necessary to engage and disengage two clutches at the same time, such as when performing a clutch-to-clutch power-on downshift. In this case, if the engagement and disengagement of each clutch are not properly synchronized, the output shaft torque will drop or the engine will rise.

In Japanese Patent Laid-Open No. 4-228967, in clutch-to-clutch power-on downshift, closed loop control of the slip rotation speed of the high gear clutch is performed before the input shaft rotation speed reaches the low side synchronous rotation speed. There has been proposed a shift control device for an automatic transmission that controls a transmission torque capacity to realize a smooth shift while synchronizing the release of a high gear clutch and the engagement of a low gear clutch.

[0004]

However, in the above-mentioned one, since the transmission torque capacity of the high gear clutch is controlled by the closed loop control, the transmission torque capacity of the high gear clutch changes due to the change of the input shaft rotation speed. Before, the sampling time for accurately detecting the input shaft rotation speed, the dead time from the detection of the input shaft rotation speed to the transmission of the control signal, and the actual transmission torque capacity changes from the transmission of the control signal to the target value. Since there is a response time, etc., and a delay occurs in the control system, it is difficult to control the transmission torque capacity of the high gear clutch to a desired value in a short period of the gear shifting process, and smooth gear shifting can be executed. It can be difficult in reality.

The present invention has been made to solve the above-mentioned conventional problems, and in the clutch-to-clutch power-on downshift, shift control of an automatic transmission capable of realizing smooth shift without performing closed-loop control. The purpose is to provide a device.

[0006]

SUMMARY OF THE INVENTION As shown in FIG. 1, the present invention provides a clutch toe by releasing a high speed stage side friction engagement element and engaging a low speed stage side friction engagement element. A shift control device for an automatic transmission that performs clutch power-on downshift, means for detecting that there is a decision to perform the downshift, means for detecting an input shaft torque Tin of the automatic transmission, and Means for determining a first time period after the determination and a second time period after the first time period has elapsed when it is determined that the downshift should be executed; and within the first time period, The first control is performed to reduce the transmission torque capacity of the high speed side friction engagement element to a value at which the output shaft torque of the automatic transmission does not become negative,
A value that, within the second time period, a value Tch obtained by converting the transmission torque capacity of the high speed gear side friction engagement element on the input shaft is equal to the input shaft torque Tin detected by the means for detecting the input shaft torque. The value Tcl converted on the input shaft of the transmission torque capacity of the low speed side frictional engagement element at the same time is increased to | Tin−Tch | <Tcl <Tch × (high speed gear ratio / low speed gear ratio) The second control is performed so as to satisfy the above relationship, and after the second time has elapsed, a value Tcl converted on the input shaft of the transmission torque capacity of the low speed stage side friction engagement element is changed to the input shaft. Control means for increasing the input shaft torque Tin detected by the torque detecting means to a value equal to or greater than the torque, and after increasing the torque, transfer torque capacity of the high-speed-stage friction engagement element is reduced to zero. With By a, it is obtained by achieving the above object.

That is, when it is detected that there is a decision to execute the downshift, the transmission torque capacity of the high speed gear side friction engagement element is automatically determined in the first control within the first time period after the decision. By reducing the output shaft torque of the transmission to a value that does not become negative, the input shaft rotation speed is quickly increased while preventing the output shaft torque from reversing from positive to negative.

Next, in the second control during the second time from the lapse of the first time, the value T of the transmission torque capacity of the high speed gear side friction engagement element converted on the input shaft.
ch is increased to a value equal to the input shaft torque Tin detected by the means for detecting the input shaft torque, and at the same time, a value Tcl of the transmission torque capacity of the low speed side friction engagement element converted on the input shaft. , | Tin-Tch | <Tcl
<Tch × (high-speed gear ratio / low-speed gear ratio) is increased so as to satisfy the relationship, and prevents shock at the time of engaging the low-speed side frictional engagement element while suppressing rising of the input shaft rotation speed. In addition, the low-speed-stage side frictional engagement element is given a transmission torque capacity to surely increase the input shaft rotation speed,
The low-speed-stage frictional engagement element is engaged during the low-speed-stage synchronization so that the torque phase can be achieved. Further, in the third control after the lapse of the second time, the input shaft torque detected by the means for detecting the input shaft torque is the value Tcl converted on the input shaft of the transmission torque capacity of the low speed stage side friction engagement element. By increasing the value to the value equal to or higher than Tin, and then decreasing the value, the transmission torque capacity of the high-speed-stage frictional engagement element is decreased to zero, whereby the gear shift can be surely completed within a predetermined time.

As a result, smooth gear shifting can be executed without depending on the closed loop control.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows a specific example of an automatic transmission to which the present invention is applied.

This automatic transmission comprises a torque converter 2 and a transmission unit 4. The torque converter 2 includes a pump 12 connected to the engine output shaft 10, a stator 16 and a turbine 18 connected to a transmission case 15 via a one-way clutch 14. The turbine 18 is connected to an input shaft 20 of the transmission, and the input shaft 20 is connected to a high gear pair 22 via a high gear clutch (high speed gear side friction engagement element) CH. The high gear pair 22 includes a driving gear 22a and a driven gear 22b. At the same time, the input shaft 20 is connected to the low gear pair 24 via a low gear clutch (low speed stage side friction engagement element) CL.
Like the high gear pair 22, the low gear pair 24 also includes a drive gear 24a and a driven gear 24b.

The high gear clutch CH and the low gear clutch CL can have transmission torque capacities corresponding to the supplied hydraulic pressures, and the converted values on the input shaft 20 are represented by Tch and Tcl, respectively. Also, high gear pair 2
2 and the driven gears 22b and 24b of the low gear pair 24 are
It is connected to the output shaft 26 and always rotates in the same direction.

The release or engagement of each clutch CH, CL is executed by driving an electromagnetic valve or a linear solenoid (not shown) in the hydraulic control device 30 based on a command from the computer 40.

The computer 40 includes various sensor groups 50.
From the vehicle speed sensor 51 (a signal of the rotation speed of the output shaft 26), the throttle sensor 5
In addition to basic signals such as the throttle opening signal from 2, the pattern select signal from the pattern select switch 53, the shift position signal from the shift position switch 54, and the foot brake signal from the brake switch 55, the input shaft speed sensor 56. The rotational speed signal of the input shaft 20 from is input.

In the computer 40, the first time after the judgment to execute the downshift, the calculation of the input shaft torque Tin of the automatic transmission, the judgment to execute the downshift, and the elapse of the first time have elapsed. Determination of the second time, calculation of values Tch and Tcl obtained by converting the transmission torque capacities of the clutches CH and CL on the input shaft 20, and the like are performed.

The operation of this embodiment will be described below. FIG.
The control flow executed by the computer 40 is shown in FIG.

First, in step 102, if there is a shift determination, it is determined whether or not it is a downshift. If it is not a downshift, proceed to step 104,
Control by upshift logic. Further, even if it is a downshift, if it is determined in the next step 106 that the power is not on, the process proceeds to step 108, and control is performed by the power off downshift logic.

When it is determined in step 102 and step 106 that downshift and power are on, the process proceeds to the next step 110, and information such as engine speed or throttle opening signal is used by a known method. Then, the input shaft torque Tin is calculated.

In the next step 112, it is determined whether or not time t1 (first time) has elapsed from the shift determination (or the subsequent shift command). As a result, when the first time has not yet been reached, it is determined that it is the process I and the step 1
14, the first control is performed.

In the first control in the process I, the hydraulic pressure for closing the pack clearance is supplied to the low gear clutch CL, and the hydraulic pressure of the high gear clutch CH is taken into consideration, as shown in FIG. Is set to a value that does not become negative. Here, the output shaft torque Tout is the gear ratio of the high speed stage and the low speed stage respectively i
_{Let H} and i _L be given by the following equations.

Tout = Tch × i _H −Tcl × i _L

As a result, the low gear clutch CL can have a proper transmission torque capacity in the next step II, can prevent the output shaft torque Tout from being reversed, and as shown in FIG. The speed Nin can be raised quickly.

Thereafter, the process returns to step 110 again, and the first control in step I is executed until the first time elapses.

When the elapse of the first time is confirmed in step 112, the process proceeds to the next step 116, and it is determined whether or not time t2 (second time) has elapsed from the shift determination. Here, from time t1 to time t2 is the second time, and
II is executed.

Until it is judged at step 116 that the second time has ended, step II is supposed to be executed and the routine proceeds to step 118, where the second control is executed.

The second control in this process II starts from the time when the input shaft rotation speed Nin does not exceed the low gear side synchronous rotation speed even when the input shaft torque Tin is maximum among the variations and the transmission torque Tch of the high gear clutch CH is 0. , Fig. 4
As shown in a, the value Tch obtained by converting the transmission torque capacity of the high gear clutch CH on the input shaft is made equal to the input shaft torque Tin, and at the same time, the value Tcl obtained by converting the transmission torque capacity of the low gear clutch CL on the input shaft is calculated. Even if variations are taken into consideration, control is performed within a range that satisfies the following formula.

| Tin−Tch | <Tcl <Tch × (i _H / i _L )

According to the second control, the high gear clutch CH is provided with a torque capacity that is in balance with the input shaft torque Tin, so that the rising speed of the input shaft 20 is suppressed and a shock is prevented when the low gear clutch is engaged. , The low gear clutch CL is given a torque capacity to surely increase the input shaft rotation speed Nin as shown in FIG.
In the inside, the input shaft rotation speed Nin reaches the low gear side synchronous rotation speed, and since Tch + Tcl> Tin, the low gear clutch CL is surely engaged at the same time, and the torque phase is established.

If synchronization is not performed during the process II, the low gear clutch CL is processed in the next process III.
The value Tcl obtained by converting the transmission torque capacity of the above into the input shaft 20 is increased and synchronized.

If it is determined in step 116 that the second time has elapsed, and if it is determined in the next step 120 that the gear shifting process has not been completed yet, the process proceeds to step 122 as step III to execute the third control.

The third control in this step III is shown in FIG.
As shown in, the value Tcl obtained by converting the transmission torque capacity of the low gear clutch CL on the input shaft 20 is increased to the input shaft torque Tin or more, and the input shaft torque Tin is changed to the low gear clutch C.
After making it possible to transmit only by L, the value Tch obtained by converting the transmission torque capacity of the high gear clutch CH on the input shaft 20 is reduced to 0 at a predetermined gradient to release the high gear clutch CH.
The shift is ended.

FIG. 4 shows the case where the actual input shaft torque Tin is equal to the estimated input shaft torque, and FIG. 5 shows the case where the actual input shaft torque Tin exceeds the estimated value by a predetermined amount. FIG. 6 shows the case where the amount is below the predetermined amount. At this time, in any case, the hydraulic control method for determining the transmission torque capacity of each clutch CH, CL is the same.

As described above, according to this embodiment, the process I
The first control in step 1 can prevent the output shaft torque Tout from reversing from positive to negative, and the input shaft rotation speed Nin can be quickly increased, and the second control in step II can prevent the input shaft rotation speed Nin from rising. , A shock at the time of engaging the low gear clutch CL is prevented, and the low gear clutch CL has a transmission torque capacity to surely increase the input shaft rotation speed Nin, and the low gear clutch CL is engaged at the time of low gear side synchronization, It can be done in the torque phase,
By the third control in step III, the shift can be surely completed within the predetermined time. As a result, a smooth shift can be realized without executing the closed loop control.

[0035]

As described above, according to the present invention,
By appropriately controlling the hydraulic pressures of the high gear clutch CH and the low gear clutch CL, it is possible to realize a smooth gear shift even if the input shaft torque varies with respect to the estimated value without executing the closed loop control.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the gist of the present invention.

FIG. 2 is a schematic configuration diagram showing an automatic transmission to which the present invention is applied.

FIG. 3 is a flowchart showing a shift control of the present embodiment.

FIG. 4 is a diagram showing a change in each control amount in the shift control of the present embodiment.

5 is a diagram showing a case where the input shaft torque exceeds a predetermined value by a predetermined value as compared with FIG.

6 is a diagram showing a case where the input shaft torque is lower than an estimated value by a predetermined value as compared with FIG.

[Explanation of symbols]

 2 ... Torque converter 4 ... Transmission section 10 ... Engine output shaft 12 ... Pump 14 ... One-way clutch 15 ... Case 16 ... Stator 18 ... Turbine 20 ... Transmission input shaft 22 ... High gear pair 24 ... Low gear pair 26 ... Output shaft 30 ... Hydraulic control device 40 ... Computer 50 ... Various sensor groups CH ... High gear clutch CL ... Low gear clutch

Claims (1)

[Claims] 1. Disengaging the high speed step side friction engagement element,
A shift control device for an automatic transmission that engages a low-speed-side friction engagement element to perform a clutch-to-clutch power-on downshift, and means for detecting that there is a decision to execute the downshift, Means for detecting the input shaft torque Tin of the automatic transmission; a first time after the judgment when the downshift is to be executed, and a second time after the first time has elapsed. Means for determining the time, and performing the first control for decreasing the transmission torque capacity of the high speed gear side friction engagement element to a value at which the output shaft torque of the automatic transmission does not become negative within the first time, Within the second time period, a value Tch obtained by converting the transmission torque capacity of the high speed gear side friction engagement element on the input shaft is equal to the input shaft torque Tin detected by the means for detecting the input shaft torque. The value Tcl obtained by converting the transmission torque capacity of the low speed side frictional engagement element on the input shaft at the same time as | Tin−Tch | <Tcl <Tch × (high speed gear ratio / low speed gear ratio) Value of the transmission torque capacity of the low-speed-stage frictional engagement element converted to the input shaft Tcl after the second time has elapsed.
Is increased to a value equal to or larger than the input shaft torque Tin detected by the input shaft torque detecting means, and after being increased, the transmission torque capacity of the high speed gear side friction engagement element is reduced to zero. A shift control device for an automatic transmission, comprising: a control unit that performs control.