JP2008051268A - Shift control device of automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate a heat load of a friction element while effectively eliminating a shock generated when fastening the friction element, in the shift operation of an automatic transmission. <P>SOLUTION: After starting the shift operation of a Step S1, before starting an inertia phase of Step S13, pre-torque-down for reducing input torque Ti up to the balance torque T<SB>pred</SB>of input torque T<SB>initial</SB>or smaller at a shift operation starting time, larger than a torque down value T<SB>d</SB>after starting the inertia phase, and fastening operation for setting a transmission torque capacity Tcl of a fastening friction element to the balance torque T<SB>pred</SB>are performed in Step S10 to Step S12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In a stepped transmission mechanism of a vehicle having a plurality of friction elements that cut off or connect a driving force, the present invention is to realize the speed change operation suitably when releasing and fastening these friction elements and performing a speed change operation. The present invention relates to a control device.

2. Description of the Related Art Conventionally, an automatic transmission that performs a shift operation based on an accelerator operation and a vehicle speed by a driver without depending on a driver's gear change operation has been known. When power is being transmitted from the engine to the wheels via the automatic transmission and an upshift, which is a shift operation that changes the gear ratio to the high gear side, an inertia torque is generated. There is a problem that a shock occurs or the thermal load of the friction element increases.
Therefore, in an upshift, as an invention for reducing the engine output and the input torque to the automatic transmission so that the shock is not easily transmitted from the automatic transmission to the wheels and the thermal load of the friction element is reduced. Conventionally, for example, the one described in Patent Document 1 is known.
The shift control device for an automatic transmission described in Patent Document 1 is used for a shift operation in a power train of a vehicle in which an engine, a torque converter, an automatic transmission, and a wheel-side load are sequentially connected in series. Is for predicting the start of the inertia phase when the rotational speed of the input shaft of the automatic transmission starts to change, and reducing the input torque to the automatic transmission from the predicted start of the inertia phase.

  When the outline of the torque-down control described in Patent Document 1 is shown in a time chart, it is generally shown in FIG. Conventional torque-down control will be described along the time chart of FIG. First, at the instant t1, when the next gear stage (target gear ratio) NEXTGP indicated by a solid line deviates from the current gear stage (actual gear ratio) CURGP indicated by a broken line, a gear shifting operation is started. The transmission torque capacity command value Tcl * of the engagement-side clutch that is released while the current shift speed is selected and is engaged when the next shift speed is selected is a predetermined gradient from 0, that is, a predetermined change rate, as indicated by a solid line, Increase with. The actual transmission torque capacity Tcl rises from the following instant t2 with a slight delay from the command value. At the subsequent instant t3, the transmission torque capacity Tcl matches the input torque Ti of the automatic transmission. At this coincidence, the inertia phase starts. This torque is called a balance torque.

  Therefore, the instant t3 at which the inertia phase starts is predicted, and the engine torque Te is decreased with a ramp gradient from the instant t3. Along with this, the input torque Ti also decreases. The engine torque Te is kept decreasing from the subsequent instant t4 to the instant t5, and the engine torque Te is increased with a ramp gradient from the instant t5 to the subsequent instant t6 to return to the engine torque Te before the instant t3. Such a decrease in engine torque Te at instants t3 to t6 is torque down control. Similarly, the input torque Ti is also reduced in torque. During the torque down control, the transmission torque capacity command value Tcl * of the engagement side clutch is gradually increased, the release side clutch is released, and so-called clutch changeover control is executed. When the torque-down control ends at the instant t6, at the subsequent instant t7, the transmission torque capacity is increased at once and the engagement side clutch is completely engaged.

When the engagement-side clutch is completely engaged, the clutch changeover control is completed, and the inertia phase ends. Therefore, at the instant t7, the current shift stage CURGP coincides with the next shift stage NEXTGP, and the shift operation ends.
JP-A-10-184410

  However, the conventional shift control device for an automatic transmission still has the problems described below. That is, the engine torque Te is converted by the torque converter into the input torque (turbine torque) Ti, and the input torque Ti is large while the input torque Ti is input to the automatic transmission and the vehicle is driven. For this reason, the balance torque of the shift operation is also Ti, which is a large value. Then, even if the transmission torque capacity of the engagement side clutch is increased from 0 to Ti with a predetermined gradient, a certain amount of time (t3−t2) is required, and a rapid shift operation cannot be realized.

  Further, in the conventional shift control device for an automatic transmission as described above, the paragraph number (0032) of Patent Document 1 describes that the instant t3 at which the inertia phase starts is predicted. As described in paragraphs (0025) and (0041) of FIG. 1, an input shaft rotational speed sensor that detects the rotational speed (= turbine rotational speed) of the input shaft of the automatic transmission can actually detect a rotational change. By detecting the minimum rotational speed dNs, the engine is controlled and the torque reduction of the input torque is started. That is, the instant t3 at which the inertia phase starts is not predicted in advance, but the start of the inertia phase is detected from the change in the input shaft rotation speed. Then, the engine torque Te and the input torque Ti are not reduced at the instant t3 shown in FIG. 4, but the engine torque Te and the input torque Ti are reduced at an instant after the instant t3. With such shift control of Patent Document 1 in which torque down control is started after the start of the inertia phase, the shock that occurs when the friction element is engaged cannot be eliminated, and the thermal load of the friction element is reduced. It cannot be reduced.

  The present invention is capable of starting the torque reduction of the input torque in time for the start of the inertia phase in the speed change operation, effectively eliminating the shock generated when the friction element is engaged, and reducing the thermal load of the friction element. The present invention proposes a shift control device for an automatic transmission.

For this purpose, a shift control device for an automatic transmission according to the present invention is as described in claim 1.
An automatic transmission having an input shaft to which torque is input from the prime mover side, an output shaft for outputting torque to the load side, and a plurality of friction elements for shifting between these input and output shafts,
The engagement-side friction element that is released until the start of the speed change operation and is engaged when the speed change operation is completed among the speed change friction elements when the speed change operation is released and engaged to achieve the target speed ratio. Fastening side friction element control means for operating the transmission torque capacity of
When the transmission torque capacity reaches the input torque of the input shaft and the inertia phase starts, a torque down control means for reducing the input torque to a predetermined torque down value and changing the actual gear ratio to the target gear ratio. In the shift control device of the automatic transmission provided,
Pre-torque down control means for reducing the input torque to a predetermined torque value that is greater than the torque down value and smaller than the input torque at the start of the shift operation after the start of the shift operation and before the start of the inertia phase It is characterized by.

According to the speed change control device of the present invention, the speed change operation is started when the target speed ratio deviates from the current speed ratio, and then the speed change operation is completed when the current speed ratio matches the target speed ratio. In order to perform pre-torque down control to reduce the torque of the prime mover before starting the inertia phase, as well as performing engine torque down control in the inertia phase,
By reducing the input torque before the start of the inertia phase, the inertia phase can be caused at an early stage, and the shift time from the judgment of the shift to the end of the shift can be shortened. Further, the engine torque can be reduced in time for the start of the inertia phase, and the shock that occurs when the friction element is engaged can be effectively eliminated.
In addition, since the target transmission torque capacity is set to a balance torque equal to or less than the input torque immediately before the shifting operation, the transmission torque capacity at the start of the inertia phase can be made lower than the conventional input torque, and the engagement side friction element The heat load can be reduced.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a vehicle equipped with a shift control device for an automatic transmission according to an embodiment of the present invention, together with its control system. Reference numeral 1 denotes an engine, and 2 denotes an automatic transmission. The power train is configured.
The engine 1 controls the throttle valve opening independently of the driver's accelerator pedal operation, so that the output (number of revolutions and torque) is adjusted. The engine output is input to the automatic transmission 2 via the torque converter 3. Shall be.

The opening degree of the throttle valve of the engine 1 is determined mainly by the depression amount of an accelerator pedal (not shown), and the opening degree is controlled by a throttle actuator. Further, in the shift operation of the automatic transmission 2, the engine torque is adjusted as described later for the purpose of controlling the shift operation.
The engine controller 4 controls the throttle valve opening of the engine 1.

  The engine controller 4 performs normal engine control such as fuel injection amount control. For this reason, the engine controller 4 includes a signal from an accelerator opening sensor (not shown) that detects an accelerator opening of an accelerator pedal (not shown). A signal from an engine rotation sensor (not shown) that is provided in the engine 1 and detects the engine rotation speed is input, and normally a normal target engine rotation speed corresponding to the vehicle operating state such as the accelerator opening and the engine rotation speed is set. The engine output control including the fuel injection amount control and the ignition timing control is performed so that this is achieved.

The automatic transmission 2 is a linear motion that directly controls the hydraulic fluid pressure to be supplied to a frictional element for shifting such as a hydraulically operated clutch or a hydraulically operated brake that determines a power transmission path (shift stage) of the gear transmission system. For this reason, hydraulic fluid duty solenoids are inserted into a control valve (not shown) for speed change control provided in the automatic transmission 2 by the number of the friction elements for speed change.
These hydraulic fluid duty solenoids individually control the hydraulic fluid pressure of the corresponding friction elements, and selectively engage the friction elements to bring the automatic transmission 2 into a state where a predetermined gear stage is selected. To get.
The automatic transmission 2 shifts and outputs the engine power at a gear ratio corresponding to the selected shift speed.

  The transmission controller 5 receives the accelerator opening and the engine speed signal of the engine 1 via the engine controller 4 and detects the input speed input from the turbine of the torque converter 3 to the automatic transmission 2. A signal from an input rotation sensor (not shown), a signal from an output rotation sensor (not shown) for detecting the output rotational speed of the automatic transmission 2, and the temperature of hydraulic fluid supplied to the friction element for shifting (hereinafter referred to as AT oil temperature) ) To detect a signal from a temperature sensor (not shown).

The transmission controller 5 executes a known control program (not shown) based on the input information described above, and controls the automatic transmission 2 to change the speed as follows.
First, a gear stage NEXTGP suitable for the current operating state is obtained from a vehicle speed and an accelerator opening obtained by calculation from the transmission output rotation speed, based on a planned shift pattern (not shown).
If the preferred gear NEXTGP and the current selected gear CURGP match, the gear solenoid is not issued as a shift command, and the duty duty drive duty is kept as it is. Maintain selected gear CURGP.
However, if the currently selected shift stage CURGP is different from the preferred shift stage NEXTGP, the shift from the selected shift stage CURGP to the preferred shift stage NEXTGP is performed by changing the drive duty of the corresponding duty solenoid by issuing a shift command. The release of the friction element for shifting and the fastening switching are executed.

  FIG. 2 is a flowchart showing pre-torque down control executed by the transmission controller 5 and the engine controller 4 in cooperative control when the automatic transmission 2 performs a shift in this embodiment. First, in step S1, it is determined whether or not the preferred gear stage NEXTGP has deviated above the currently selected gear stage CURGP, that is, whether or not an upshift command is to be issued. If the preferred shift speed NEXTGP and the current selected shift speed CURGP match, the up-shift gear shift command is not issued (NO), and this flowchart is terminated. On the other hand, when the preferred gear stage NEXTGP deviates above the currently selected gear stage CURGP, an upshift command is issued (YES), and the gear shifting operation is started.

  In the next step S2, it is determined whether the AT oil temperature, which is the temperature of the hydraulic fluid in the automatic transmission 2, is equal to or higher than a set value. This step confirms whether the viscosity, temperature, etc. of the hydraulic fluid are in an optimum range for realizing the speed change operation according to the present invention. This set value is set to a predetermined value obtained in advance through experiments or the like. When the AT oil temperature is lower than the set value (NO), this flowchart is terminated. Thus, known torque down control without pre-torque down control is performed until the AT oil temperature is sufficiently warmed. On the other hand, when the AT oil temperature is equal to or higher than the set value (YES), the process proceeds to the next step S3.

  In step S3, it is determined whether the accelerator opening is equal to or greater than a set value. When the accelerator opening is lower than the set value (NO), this flowchart is ended and a known torque down control without pre-torque down control is performed. This is because if the accelerator opening is sufficiently small, the driver does not intend to accelerate. On the other hand, when the accelerator opening is equal to or larger than the set value (YES), the process proceeds to the next step S4.

  In step S4, it is determined whether the engine speed is equal to or higher than a set value. When the engine speed is lower than the set value (NO), this flowchart is terminated and a known torque down control without pre-torque down control is performed. On the other hand, if the engine speed is greater than or equal to the set value (YES), the process proceeds to the next step S5.

  In step S5, it is determined whether or not the driver's intention to accelerate is the sport mode, that is, whether or not the driver desires a sharp run. Specifically, the rate of change of the accelerator opening is obtained. If the rate of change of the accelerator opening is greater than a predetermined value, it is determined that the intention to accelerate is large and the sport mode is desired. When the sport mode is not desired (NO), this flowchart is ended, and a known torque down control without pre-torque down control is performed. On the other hand, when the sport mode is desired (YES), the driver expects a quick shift, and therefore the process proceeds to the next step S6 and pre-torque down control is executed.

In step S6, a pre-torque down amount is calculated as preparation for performing pre-torque down to reduce the input torque Ti of the automatic transmission 2 that is also the turbine torque of the torque converter 3. The pre-torque down amount is obtained by referring to a map stored in advance based on the accelerator opening degree read in step S3 or the input torque T _initial at the start of the shift operation. Alternatively, it is calculated from a function using the accelerator opening or the input torque T _initial at the start of the shift operation as a parameter. In this embodiment, the pre-torque down amount is increased as the acceleration intention detected in step S5 is larger, that is, as the input torque is larger. Note that the acceleration intention may use a change rate such as the accelerator opening.

In the next step S7, the balance torque T _pred is calculated by subtracting the pre-torque down amount from the input torque T _initial at the start of the shift operation. When the input torque is a value T _d when a known torque is reduced, which will be described later, the relationship T _initial ≧ T _pred > T _d is established. The greater the intention to accelerate, the smaller the balancing torque T _pred .

In the next step S8, a predetermined pre-torque down change rate when the input torque Ti is decreased is calculated. The pre-torque down change rate is obtained by referring to a map stored in advance based on the accelerator opening degree read in step S3 or the input torque T _initial at the start of the shifting operation. Alternatively, it is calculated from a function using the accelerator opening or the input torque T _initial immediately before the start of the shift operation as a parameter.
Then, by dividing the pre-torque down amount by the predetermined pre-torque down change rate, the input torque ramp reached to reduce the input torque Ti at the start of the shifting operation that becomes the upshift to the balance torque T _pred Time T2 is calculated.
Note that the pre-torque down change rate described above is made steeper as the detected acceleration intention (accelerator opening change rate obtained in step S5) is larger.

In the next step S9, a predetermined transmission torque capacity for increasing the transmission torque capacity of the friction element for shifting (hereinafter referred to as the engagement-side friction element) that is released until the start of the shift operation and is engaged when the shift operation is completed. Calculate the rate of change. Then, the transmission torque capacity ramp arrival time T1 required to increase the transmission torque capacity of the engagement side friction element from 0 to the balance torque T _pred at the predetermined transmission torque capacity change rate is calculated. Note that the predetermined transfer torque capacity change rate may be set in advance by a value obtained by an experiment and fixed to the set value.

In the next step S10, the difference time T1-T2 is obtained by subtracting the input torque ramp arrival time T2 from the transmission torque capacity ramp arrival time T1. Then, the pre-torque down of the input torque Ti and the fastening operation of the fastening side friction element are started. When the difference time T1-T2 is larger than 0, first, the engagement side friction element is started to be engaged at an engagement speed corresponding to the predetermined transmission torque capacity change rate, and then the predetermined pre-torque down is performed. Start pre-torque down at the rate of change. On the contrary, when the difference time T1−T2 is smaller than 0, first, the pre-torque down is started at the predetermined pre-torque down change rate, and then the fastening is performed at the fastening speed corresponding to the predetermined transmission torque capacity change rate The fastening operation of the side friction element is started. In any case, the input torque Ti and the transmission torque capacity Tcl reach the balance torque T _pred at the same time.

In the next step S11, it is determined whether or not the input torque Ti has reached the balance torque T _pred . If it has not yet reached (NO), the process returns to step S11, and the input torque Ti is monitored until it reaches, and the input torque Ti is continuously reduced at the predetermined pre-torque down change rate. The input torque target decrease amount Ttarget has a gradient corresponding to the predetermined pre-torque down change rate.
On the other hand, when the input torque Ti reaches the balance torque (YES), the process proceeds to the next step S12.

In step S12, the input torque Ti is held at the balance torque T _pred .
In the next step S13, it is determined whether the inertia phase has started. This determination is made based on whether or not the effective gear ratio Gr, which is a value obtained by dividing the input shaft rotational speed of the automatic transmission 2 by the output shaft rotational speed, has changed. If the inertia phase has not yet started (NO), the process returns to step S12 and the input torque Ti is held at the balance torque T _pred . On the other hand, when the inertia phase starts (YES), this flowchart ends.
After the end of this flowchart, known torque down control is performed to further reduce the input torque Ti to a predetermined value _Td from the balance torque _Tpred .

FIG. 3 is a time chart showing the speed change operation of this embodiment. The operational effects of the present embodiment will be described with reference to FIG.
Before the start of the shift operation, the currently selected shift speed CURGP indicated by a broken line coincides with the preferred shift speed NEXTGP indicated by a solid line, the input torque target decrease amount Ttarget of the automatic transmission 2 is 0, and the engine torque Te is set to the accelerator opening. The effective gear ratio Gr holds a value corresponding to the current selected gear stage CURGP, and the input torque Ti of the automatic transmission 2 is a value T _{initial obtained} by multiplying the engine torque Te by the converter ratio of the torque converter 3. The transmission torque capacity command value Tcl * and the actual transmission torque capacity Tcl of the engagement side clutch of the automatic transmission 2 are 0, and the output torque To of the automatic transmission 2 is divided by the _initial gear ratio Gr. It is the value.

First, at the instant t11, when the preferred gear stage NEXTGP indicated by the solid line deviates above the currently selected gear stage CURGP indicated by the broken line, the upshift operation is started (YES in step S1). From the next instant t12, the engagement-side friction element is operated to the engagement side, and the transmission torque capacity Tcl indicated by the broken line is increased at a predetermined transmission torque capacity change rate. From the subsequent instant t13, the input torque Ti is reduced at the predetermined pre-torque down change rate (step S10). The input torque Ti is aimed at a value lower than the value T _initial at the start of the shifting operation (instantaneous t11). The actual transmission torque capacity Tcl indicated by the broken line is slightly delayed from the transmission torque capacity command value Tcl * indicated by the solid line due to the characteristics of the hydraulic response of the automatic transmission 2 that controls the frictional element for speed change by hydraulic pressure. . Therefore, the transmission controller 5 stores in advance a response delay time that is a unique value for each automatic transmission 2, and commands the transmission torque capacity command value Tcl * to the automatic transmission 2 earlier by the response delay time. .

From the instant t13 to the subsequent instant t14, the input torque target decrease amount Ttarget increases with a gradient corresponding to the predetermined pre-torque down change rate. Therefore, the engine torque Te decreases with the same gradient as the absolute value of this gradient. At the instant t14, the target decrease amount Ttarget becomes a value for achieving the balance torque, and the input torque Ti coincides with the balance torque T _pred . The transmission torque capacity Tcl also coincides with the balance torque T _pred at the instant t14 (YES in step S11).
From the instant t14, the input torque target decrease amount Ttarget is held at the pre-torque down amount in step S6. Therefore, the engine torque Te also becomes a constant value, and as a result, the input torque Ti is also held at the balance torque T _pred (step S12). From the instant t14, the clutch effective gear ratio Gr starts to change, that is, the inertia phase starts.

According to this embodiment, the required time T _GC 1 from shifting operation start time (instant t11) until the inertia phase start (instant t14) is the time required in the conventional embodiment shown in FIG. 4 T _GC 2 (= t3- It can be seen that the effect is shorter than t1).

Returning to FIG. 3, when the change dGr of the effective gear ratio Gr is detected at the subsequent instant t15 (YES in step S13), the pre-torque down control is terminated at the subsequent instant t16, and the input torque Ti is balanced with the torque. A known torque-down control is started to make _Td lower than _Tpred .

That is, during the pre-torque down from the instant t14 to the instant t16, the input torque target decrease amount Ttarget is made constant (step S12). Therefore, the engine torque Te also becomes a constant value, and as a result, the input torque Ti is also held at a constant value T _pred . The input torque target decrease amount Ttarget is held at the maximum value from the instant t16.

The control to maintain the input torque target decrease amount Ttarget, which is executed from the instant t16, at the maximum value is performed until the subsequent instant t17. For this reason, the engine torque Te is further lower than the value up to the instant t16. As a result, the input torque Ti is also maintained at _Td , and the torque is reduced. After the instant t16, the transmission torque capacity Tcl is gradually increased.

From the instant t17 to the subsequent instant t18, the input torque target reduction amount Ttarget is reduced from the maximum value to zero. For this reason, the engine torque Te returns to the original value corresponding to the accelerator opening, neither pre-torque down nor torque down, and as a result, the input torque Ti also returns to the value T _initial at the start of the shifting operation, and the inertia phase is End at instant t18.

  At the subsequent instant t19, the engagement side friction element is completely engaged, and the transmission clutch capacity Tcl is increased to a sufficiently large value. This completes the upshifting operation.

For reference, the output torque To of the automatic transmission 2 will be described. Before the start of the shift operation (up to instant t11), the input torque Ti is a value obtained by processing with the effective gear ratio Gr at that time. From the instant t11 at which the shift operation is started to the instant t12 that follows, the value is the same as that before the start of the shift operation (to instant t11). Since the transmission clutch capacity of the engagement-side friction element increases from 0 after the instant t12, the output torque To decreases after the instant t12. Since the input torque Ti decreases after the instant t13, the output torque To further decreases after the instant t13.
When the input torque Ti reaches the balance torque at the instant t14, the output torque To becomes a minimum value, and after the instant t14, the output torque To starts increasing. Thereafter, the output torque To stabilizes for a while at a value between the value before the start of the shift operation and the minimum value of the instant t14. After the speed change operation is completed (from instant t19), the input torque Ti is a value processed by the effective gear ratio Gr at that time.

By the way, according to the above-described embodiment, as shown in FIG. 3, the input torque Ti is made greater than the torque-down value _Td after the shift operation is started (instant t11) and before the inertia phase is started (instant t14). Since the input torque T _{initial is} less than the balance torque T _pred and the target transmission torque capacity Tcl of the engagement side friction element is set to the balance torque T _pred ,
The input torque Ti can be reduced to the balance torque T _pred so as to be in time for the start of the inertia phase in the speed change operation (instant t14), and the shock generated when the friction element is _engaged can be effectively eliminated. Further, since the input torque Ti is reduced to the balance torque T _pred , the thermal load on the fastening side friction element can be reduced, and the life of the fastening side friction element can be made longer than before.

Further, according to the present embodiment described above, the driver's acceleration intention is detected by the magnitude of the input torque in step S6, and the torque reduction amount is increased as the detected acceleration intention is larger, and is calculated in step S7. Since the balance torque T _pred is reduced,
When the acceleration intention is large, the transmission torque capacity ramp arrival time T1 calculated in step S9 is shortened. Therefore, it is possible to shorten the time T _GC1 required until the inertia phase start (instant t14) shown in the time chart of FIG. 3, and the speed change operation can be executed more quickly.

Further, according to the above-described embodiment, the pre-torque down amount that is the difference between the balancing torque T _pred and the input torque T _initial at the start of the shift operation is calculated in step S6, and the predetermined pre-torque down change is performed in step S8. The input torque ramp arrival time T2 required to reduce the input torque Ti at the start of the shifting operation to the balance torque T _pred at a rate is calculated, and in step S9, the transfer torque capacity Tcl of the engagement side friction element is set from 0 to a predetermined value. Calculate the transmission torque capacity ramp arrival time T1 required to increase to the balance torque T _pred at the transmission torque capacity change rate, and subtract the input torque ramp arrival time from the transmission torque capacity ramp arrival time in step S10 to obtain the difference time. Calculate the required differential time (T2-T1). Then, the starting side is shifted by this difference time and the engagement side friction element is operated to the engagement side at the predetermined transmission torque capacity change rate, and the input torque Ti is decreased at the predetermined pretorque down change rate.
As a result, it is possible to reduce the input torque Ti to the balance torque T _pred at an appropriate timing that is surely in time for the start of the inertia phase in the shifting operation (instant t14), and the torque is reduced when the hydraulic pressure is not sufficiently generated. Is performed to reduce the output shaft torque, thereby preventing the acceleration performance from being impaired and the occurrence of a deceleration shock. Further, it is possible to prevent the start of the torque phase from being delayed and the start of the inertia phase from being delayed.

Furthermore, since the pre-torque down change rate is increased as the detected acceleration intention is larger in step S8, the input torque ramp arrival time T2 calculated in step S8 is shorter when the acceleration intention is large. Therefore, it is possible to shorten the time T _GC1 required until the inertia phase start (instant t14) shown in the time chart of FIG. 3, and the speed change operation can be executed more quickly.

Further, according to the above-described embodiment, if the accelerator opening is less than the set value in step S3, the driver's acceleration intention is not detected, and the input torque Ti is not reduced by the pre-torque down.
When the driver does not expect a speed change operation with a quick acceleration response, the time required for the speed change operation is lengthened by taking the required time T _GC 2 of the conventional embodiment shown in FIG. 4 as intended by the driver. be able to.

  Further, the present embodiment described above realizes the engagement / release of the shift friction element of the automatic transmission 2 using the hydraulic oil, and detects and detects the AT oil temperature which is the temperature of the hydraulic oil. If it is determined in step S2 that the At oil temperature is equal to or lower than the set value, the following adverse effects can be prevented because the input torque Ti is not reduced due to the pre-torque down. That is, the hydraulic response is poor at low oil temperature, and the actual transmission torque capacity Tcl is greatly delayed compared to the transmission torque capacity command value Tcl *. Nevertheless, when the pre-torque down of the input torque is performed, an undesired shock occurs because the transmission torque capacity of the fastening side friction element does not reach a sufficient value. In this embodiment, such an undesirable shock can be avoided.

  The above description is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit of the present invention.

1 is a system diagram showing a power train of a vehicle including a shift control device for an automatic transmission according to an embodiment of the present invention, together with its control system. It is a flowchart showing the pre-torque down control of the same Example. It is a time chart showing the speed change operation | movement of the Example. It is a time chart showing the speed change operation of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Torque converter 4 Engine controller 5 Transmission controller

Claims (6)

An automatic transmission having an input shaft to which torque is input from the prime mover side, an output shaft for outputting torque to the load side, and a plurality of friction elements for shifting between these input and output shafts,
The engagement-side friction element that is released until the start of the speed change operation and is engaged when the speed change operation is completed among the speed change friction elements when the speed change operation is released and engaged to achieve the target speed ratio. Fastening side friction element control means for operating the transmission torque capacity of
When the transmission torque capacity reaches the input torque of the input shaft and the inertia phase starts, a torque down control means for reducing the input torque to a predetermined torque down value and changing the actual gear ratio to the target gear ratio. In the shift control device of the automatic transmission provided,
Pre-torque down control means for reducing the input torque to a predetermined torque value that is greater than the torque down value and smaller than the input torque at the start of the shift operation after the start of the shift operation and before the start of the inertia phase A shift control device for an automatic transmission characterized by the above. The shift control apparatus for an automatic transmission according to claim 1,
Acceleration intention detection means for detecting the driver's acceleration intention is provided,
The pre-torque down control means sets the torque down amount that is the difference between the input torque at the start of the shift and the predetermined torque value to a larger value as the detected acceleration intention is larger. Gear shift control device. The shift control device for an automatic transmission according to claim 1 or 2,
An input torque ramp arrival time calculating means for calculating an input torque ramp arrival time, which is a time required to decrease from the input torque at the start of the shift operation to the predetermined torque value;
Pre-torque down change rate calculating means for calculating a pre-torque down change rate that is a change rate of the input torque when the input torque decreases from the input torque at the start of the shifting operation to the predetermined torque value;
A transmission torque capacity ramp arrival time calculating means for calculating a transmission torque capacity ramp arrival time, which is a time required to increase the transmission torque capacity from a capacity of 0 to the predetermined torque value at a predetermined transmission torque capacity change rate;
Difference time calculation means for subtracting the input torque ramp arrival time from the transmission torque capacity ramp arrival time to obtain a difference time;
The engagement side frictional element control means operates to change the transmission torque capacity at the predetermined transmission torque capacity change rate,
The pre-torque down control means changes the input torque to the pre-torque down after the difference time elapses after the engagement-side friction element control means starts operating the transmission torque capacity at the predetermined transmission torque capacity change rate. A shift control device for an automatic transmission, wherein the shift control device decreases at a rate. The shift control apparatus for an automatic transmission according to claim 3,
A shift control apparatus for an automatic transmission, wherein the pre-torque down change rate calculated by the pre-torque down change rate calculating means is a larger value as the acceleration intention is larger. The shift control device for an automatic transmission according to claim 3 or 4,
A shift control apparatus for an automatic transmission, wherein when the acceleration intention detection means does not detect the driver's acceleration intention, the input torque is not reduced by the pre-torque down control means. In the shift control device for an automatic transmission according to any one of claims 1 to 5, wherein the engagement and release of the friction element for shifting are realized using hydraulic oil.
Comprising oil temperature detecting means for detecting the oil temperature of the hydraulic oil;
When the detected oil temperature is equal to or lower than a predetermined value, the input torque is not reduced by the pre-torque down control means.

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