JP2993227B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a shift in an automatic transmission for a vehicle, and more particularly to a shift control device for an automatic transmission capable of reducing an input torque during a shift.

[0002]

2. Description of the Related Art Conventionally, input torque to an automatic transmission has been temporarily reduced in order to suppress a sudden change in output shaft torque during shifting, that is, a shift shock. One example is described in Japanese Patent Application Laid-Open No. 56-35857. In the invention described in this publication, the engine torque is reduced immediately before the end of the inertia phase at the time of a downshift. That is, if the input torque at the time of synchronizing with the shift speed after the shift is large, the fluctuation of the output shaft torque is also large, so that the shift shock may be large and the frictional engagement to be performed to execute the shift is performed. If the torque applied to the device is small, the engagement timing may be delayed. Therefore, in order to solve such inconvenience, in the conventional invention, the engine torque is reduced immediately before the end of the inertia phase to reduce the shift shock. I have to do that.

[0003]

Incidentally, simultaneous shifts and clutch-to-clutch shifts are known as forms of shifts in automatic transmissions. In the former simultaneous shift, as described in, for example, JP-A-64-15560, a two-stage shift of a high-speed stage and a low-speed stage is performed by a main transmission unit that sets a reverse stage and a forward stage. In an automatic transmission in which a subtransmission portion is provided in front, a shift mode in which a main transmission portion and an auxiliary transmission portion are both switched to perform a shift operation to a predetermined shift speed as a whole of the automatic transmission. Further, in the latter clutch-to-clutch shift, for example, the clutch connecting the input shaft and the predetermined rotating member is released, and the other clutch is engaged to connect the input shaft and the other rotating member. This is a shift mode. Also in the case of these shifts, a shift shock can be reduced by reducing the input torque. However, since the torque acting on the frictional engagement device that performs the switching operation is not always constant, the timing for reducing the input torque is set to a certain time immediately before the end of the inertia phase, as in the above-described conventional invention, more specifically, If it is determined uniformly at a predetermined time point determined by the detected rotation speed, the following inconvenience may occur. That is, when the power-on downshift (downshift in a state driven by the engine) is performed in a low speed range, the input torque to the automatic transmission is large and the amount of rotation change due to the shift is small, so that the friction engagement device is reduced. The completion of the engagement is delayed with respect to the completion of the release. As a result, when the friction engagement device of the sub-transmission portion is engaged to switch to the high speed stage and the main transmission portion is down-shifted as a whole, even if the input torque reduction control is performed, After the downshift in the transmission section is completed, the sub-transmission section shifts up, and the shift shock may increase. In the case of the clutch-to-clutch shift described above, the torque capacity of the two clutches to be switched may be temporarily reduced, and the engine may start up.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a shift control device capable of obtaining good shift characteristics by performing input torque reduction control according to a running state. Things.

[0005]

The present invention achieves the above object by adopting the structure shown in FIG. That is, the present invention detects a shift in which the friction engagement device 1 is engaged during a downshift in a driving state in a shift control device of the automatic transmission A in which a shift in which the friction engagement device 1 is engaged during a shift is performed. The power-on downshift detection means 2 determines whether or not the traveling state is a traveling state in which the input torque to the automatic transmission A is large and the amount of rotation change of a predetermined rotating member associated with the downshift is small. The traveling state determination unit 3 and the traveling state determination unit 3 reduce the input torque when the traveling state determination unit 3 determines that the traveling state is the traveling state in which the input torque is large and the rotation change amount of the predetermined rotating member due to the downshift is small. The start state of the control to be performed is determined by the traveling state determination means 3 that the vehicle is not in the traveling state.
The torque down time setting means 4 which sets earlier than the start time of the control for reducing the input torque when it is determined, and the torque reduction means 5 which reduces the input torque at the set time. It is characterized by having.

[0006]

In the automatic transmission A to which the present invention is applied, a shift may occur in which the friction engagement device 1 is engaged during the shift. This is detected by the power-on downshift detection means 2. Further, the traveling state determination means 3 determines whether or not the traveling state at that time is a traveling state in which the input torque to the automatic transmission A is large and the amount of change in rotation of the predetermined rotating member due to the downshift is small. When the power-on downshift detection means 2 detects the downshift and the traveling state determination means 3 determines the traveling state, the torque down time setting means 4 sets a time at which the input torque to the automatic transmission A is reduced. The start timing of the torque reduction control when it is determined that the vehicle is in the traveling state where the input torque is large and the rotation change amount of the rotating member is small is the start of the torque reduction control when it is determined that the vehicle is not in such a traveling state. Set earlier than the time. Then, the torque reducing means 5 reduces the input torque according to the set timing. Therefore, in a traveling state in which the input torque is large and the rotation change amount of the rotating member is small, the input torque decreases at an early stage during the shift, so that the delay of engagement of the friction engagement device 1 is prevented, and as a result, In addition, the shift characteristics are improved.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing one embodiment of the present invention. The automatic transmission A shown here transmits an input torque from an engine E to a gear transmission mechanism via a torque converter 21 having a lock-up clutch 20. The gear transmission mechanism further includes a second transmission section 30 having a set of planetary gear mechanisms, and a first transmission section 40 for setting a plurality of forward gears and reverse gears by two sets of planetary gear mechanisms. Have been.

[0008] The second transmission portion 30 performs two-stage switching between high (H) and low (L). The carrier 31 of the planetary gear mechanism is connected to the turbine runner 22 of the torque converter 21. And this carrier 31
A clutch Co and a one-way clutch Fo are provided in a parallel relationship with each other between the sun gear 32 and the sun gear 32, and a brake B is provided between the sun gear 32 and the housing Hu.
o is provided.

The sun gears 41 and 42 of each planetary gear mechanism of the first transmission unit 40 are provided on a common sun gear shaft 43, and are provided on the left (front side) planetary gear mechanism of the first transmission unit 40 in the drawing. Ring gear 44 and second
A first clutch C1 is provided between the transmission unit 30 and the ring gear 33, and a second clutch C2 is provided between the sun gear shaft 43 and the ring gear 33 of the second transmission unit 30. In the first transmission section 40, the carrier 45 of the planetary gear mechanism on the left side in the figure and the ring gear 46 of the planetary gear mechanism on the right side (rear side) are integrally connected,
The output shaft 47 is connected to the carrier 45 and the ring gear 46.
Are connected.

A first brake B1 as a band brake is provided on the outer peripheral side of the clutch drum of the second clutch C2 so as to stop the rotation of the sun gear shaft 43. Hu, a first one-way clutch F1 and a second brake B2 are arranged in series, and a second one-way clutch F2 and a housing Hu between the carrier 48 and the housing Hu in the rear planetary gear mechanism. The third brake B3 is arranged in parallel.

A hydraulic circuit 50 is provided for supplying and discharging hydraulic pressure to the clutches Co, C1, C2 and the brakes Bo, B1, B2, B3. This hydraulic circuit 50
Are used to execute first to fifth gear shifts, and to execute on / off (engagement / disengagement) of the lock-up clutch 20 for the first to third solenoid valves S1, S2, S3. A lock-up solenoid valve SL and a back pressure solenoid valve SN for controlling the back pressure of an accumulator (not shown) are provided.

These solenoid valves S1, S2, S
An electronic control unit (ECU) 51 is provided to control 3, SL, and SN, and to control engine torque. The electronic control unit 51 mainly includes a central processing element, a storage element, and an input / output interface, and each of the solenoid valves S1, S2, S3, SL,
As data for controlling the SN and the engine E, a vehicle speed signal detected by a vehicle speed sensor 52, a throttle opening signal detected by a throttle opening sensor 53 attached to the engine E, and a shift output from a shift lever position sensor 54. Shift pattern selection switch 55 for position signal, power mode, economy mode, etc.
Select signal output from the water temperature sensor 5
6, a brake signal output from the foot brake switch 57 or the side brake switch 58, a signal from a Co sensor 59 for detecting the rotation speed Nco of the clutch Co of the second transmission unit 30, a first transmission C2 for detecting the rotation speed Nc2 of the second clutch C2 of the section 40
A signal or the like from the sensor 60 is input.

FIG. 3 shows the clutches Co, C1, C2 and the brakes Bo, B1, B2,
In the engagement operation table of B3, a circle indicates engagement, a blank indicates release,
A mark indicates engagement during engine braking.

The electronic control unit 51 determines a gear to be set mainly based on a shift map, a vehicle speed, and a throttle opening in accordance with the shift pattern selected by the shift pattern selection switch 55, and the determination is made. Based on the result, the solenoid valves S1, S2, S3 are appropriately turned ON / OFF to set the respective shift speeds shown in FIG.
At the time of the shift, a signal is output from the electronic control unit 51 to the engine E, and torque reduction control is performed. Specifically, this is performed by delaying the ignition timing in the engine E or reducing the fuel injection amount. The determination of the start timing and the end timing of the engine torque reduction control is performed based on the output shaft rotation speed No and the rotation speed Nc2 of the second clutch C2 detected by the C2 sensor 60, and the like.

FIGS. 4 and 5 are flowcharts showing a control routine of the input torque at the time of the power-on downshift from the third speed to the second speed. In these figures, the circled numbers indicate the same numerals. Indicate that the lines are connected.

In this shift, as can be seen from the engagement operation table shown in FIG. 3, the first transmission section 40 is downshifted from the second step to the first step, and the second transmission section 30 applies the brake Bo. This is a so-called simultaneous shift in which the gears are shifted up from low (L) to high (H) and downshifted as a whole. Therefore, first, in step 1, the second speed is changed to the second speed in the power-on state.
It is determined whether or not shifting to the high speed is being performed. If the determination result is “yes”, the process proceeds to step 2 to determine whether or not the flag F is “1”. This flag F indicates the phase of the input torque control, and is initially reset to zero. The result of the determination in the first step 2 is “no”, and the process proceeds to step 3. In step 3, it is determined whether or not the flag F is "2". Since the flag F is initially reset to zero, the determination result is "no", and the process proceeds to step 4. In step 4, it is determined whether or not the vehicle speed V is equal to or lower than a first reference vehicle speed V1. If the determination result is "no", the process proceeds to step 5 where the vehicle speed V is reduced to the first reference vehicle speed V1. The second reference vehicle speed V2 (> V1) having a larger value
It is determined whether or not: If the result of the determination is "No", the shift is a downshift from the third speed to the second speed at a high vehicle speed, so the routine proceeds to step 6, where the rotational speed of the second clutch C2 satisfies the following equation. It is determined whether or not the rotation speed has been reached.

Nc2 ≧ (No / ρ2) -β1 Here, ρ2 indicates the gear ratio of the planetary gear mechanism on the right side (rear side) in FIG. 2 of the first transmission section 40, and β1 is a predetermined constant. Therefore, this equation is equivalent to the second clutch C2
Is determined to have reached a rotational speed lower than the synchronous rotational speed (No / ρ2) in the second speed by a predetermined rotational speed (β1), and the determination result is “NO”. If so, the control process returns. If "yes", the process proceeds to step 7, sets the flag F to "1", and then proceeds to step 8 to reduce the input torque, that is, in this embodiment, the control of the engine E. Start torque down control.
Specifically, this is performed by delaying the ignition timing of the engine E.

On the other hand, if the judgment result of step 4 is "yes"
In other words, if the vehicle speed V is extremely low, the routine proceeds to step 9, where it is determined whether or not the time counted by the timer T is equal to or longer than a preset time T0.
If the determination is "no", the control process returns. If "yes", the process proceeds from step 7 to step 8 to execute the torque down control of the engine.
This timer T is a timer that starts simultaneously with the determination of the downshift from the third speed to the second speed, and has a set time T
0 is a very short time, and therefore, in the case of a low vehicle speed, the engine torque reduction control is started early after the shift is started.

If the result of the determination in step 5 is "YES", that is, if the vehicle speed is between the first reference vehicle speed V1 and the second reference vehicle speed V2, the routine proceeds to step 10, where the second clutch C2 It is determined whether or not the rotation speed Nc2 satisfies the following expression.

Nc2 ≧ (No / ρ2) -β2 Here, β2 is a constant, and is a value larger than the above-mentioned constant β1. That is, the control process of step 10 is for judging whether or not the rotational speed Nc2 of the second clutch C2 has reached a lower rotational speed by β2 than the synchronous rotational speed (No / ρ2) of the second speed. If the determination result in step 10 is "no", the control process returns. If "yes", the process proceeds to steps 7 and 8 to start the engine torque reduction control.

That is, when the vehicle speed V is a low vehicle speed equal to or lower than the first reference vehicle speed V1, the engine torque reduction control is started at the earliest time, and the vehicle speed V becomes equal to the first reference vehicle speed V1 and the second reference vehicle speed V2.
If the vehicle speed is higher than the second reference vehicle speed V2, the engine torque reduction control is started slightly later than the low vehicle speed described above. The engine torque reduction control is started at the latest time.

After the engine torque reduction control is started as described above, the flag F is set to "1", and the result of the determination in step 2 in that state is "yes". Then, it is determined whether or not the rotation speed Nc2 of the second clutch C2 has reached the rotation speed satisfying the following expression.

Nc2 ≧ (No / ρ2) -α where α is a constant smaller than the above-mentioned constants β1 and β2.
It is to judge whether or not the rotation speed 2 has approached the second-speed synchronization rotation speed very much, more precisely, whether or not the rotation speed has reached a rotation speed lower by a constant α than the synchronization rotation speed. Is "No", it means that the end of the torque down, that is, the start time of the torque return control has not arrived yet, and the control process returns. If the determination result is "Yes", the process proceeds to Step 12. To set the flag F to "2"
After that, the routine proceeds to step 13, where the end of the torque down control of the engine E, that is, the control for returning the engine torque, is started. In this engine torque return control, if the engine torque is immediately increased to the original torque, a shock due to an increase in the engine torque increases.
The motor is returned so that the torque gradually increases during a time t0 set by a predetermined timer.

Since the flag F is "2" during this torque return control, the result of the determination in step 3 is "yes". In this case, the routine proceeds to step 14 where the return of the engine torque is completed. Control process returns if the result of the determination is "No",
If "yes", the process proceeds to step 15 to end the shift from the third speed to the second speed.

If the result of the determination in step 1 is "NO", the process proceeds to step 16 where the flag F is set to "0" and the process returns.

The above-described changes in the clutch Co and the second clutch C2 and the rotation speeds Nco, Nc2 and No of the output shaft 47, changes in the ignition timing, changes in the hydraulic pressures of the brake Bo and the second brake B2, and changes in the output shaft torque. FIG. 6 is a time chart. That is, when the downshift from the third speed to the second speed is determined at time t1, the hydraulic pressure PBo of the brake Bo starts to be supplied almost simultaneously with this.
At time t2, which is slightly later than that, the hydraulic pressure PB2 starts to be discharged from the second brake B2. Accordingly, the rotation speed Nc2 of the second clutch C2 starts to increase gradually, and the output shaft torque gradually decreases. When the vehicle speed V is between the first reference vehicle speed V1 and the second reference vehicle speed V2, the second
The rotational speed Nc2 of the clutch C2 becomes the synchronous rotational speed (No
/ Ρ2), the engine torque reduction control is started at time t3 when the rotation speed reaches the low speed by the constant β2 described above. Specifically, the ignition timing is delayed. Accordingly, the second transmission unit 3
When the brake Bo of 0 starts to be engaged, the rotation speed Nco of the clutch Co, that is, the rotation speed of the sun gear 32 starts to decrease. The rotational speed Nc2 of the second clutch C2 increases as shown by the solid line in FIG. 6, and the torque return control is started at time t4 when the rotational speed is lower than the synchronous rotational speed by α.
When the number of revolutions of the clutch C2 reaches the synchronous number of revolutions Nc2 and when a preset time to elapses from the time t4, the torque return control ends and the engine torque returns to the original torque.

When the vehicle speed V is higher than the second reference vehicle speed V2, the rotational speed Nc2 of the second clutch C2 increases as shown by a dashed line in FIG. 6, and the rotational speed Nc2 becomes the synchronous rotational speed. From (No / ρ2), the engine torque reduction control is started at time t5 when the rotation speed has reached the low speed by the constant β1 described above. Specifically, the ignition timing is delayed. Then, as the speed change progresses, the rotation speed Nc2 of the second clutch C2 increases as shown by the dashed line in FIG. 6, and the torque return control starts at time t6 when the rotation speed becomes lower than the synchronous rotation speed by α. Immediately after that, the rotational speed of the second clutch C2 reaches Nc2, which is the synchronous rotational speed, and a preset time to from the time point t6.
Is elapsed, the torque return control ends, and the engine torque returns to the original torque.

Although not shown in FIG. 6, when the vehicle speed V is lower than the first reference vehicle speed V1, the third
When a short time T0 elapses from the point in time t1 when the downshift from the first gear to the second gear is determined (earlier than t3)
, The engine torque reduction control is started.
The engagement of the brake Bo of 0 advances early and the clutch Co
, The rotational speed Nco of the motor decreases early.

When the vehicle speed is lower than the first reference vehicle speed V1, the vehicle speed is between the first reference vehicle speed V1 and the second reference vehicle speed V2, and when the vehicle speed is higher than the second reference vehicle speed V2. In any case, the start timing of the torque down control of the engine E is changed according to the running state, so that the delay of the engagement of the brake Bo in the second transmission unit 30 does not occur, and as a result, the output There is no sudden change in the shaft torque, and no particular shift shock occurs.

In contrast to these controls, in the conventional control, as indicated by a broken line in FIG. 6, the start timing of the torque-down control is fixed at a time point when the vehicle speed is lower by β1 with respect to the synchronous rotation speed. , The engagement of the brake Bo is delayed with respect to the release of the second brake B2, and the rotation speed Nco of the clutch Co is reduced.
Is slowed down. This means that in the gear train shown in FIG. 2, the upshift of the second transmission unit 30 occurs after or at the end of the downshift of the first transmission unit 40, and as a result, the output shaft torque becomes as shown in FIG. 6. As shown by the broken line, an inertia torque occurs due to the delay of the engagement of the brake Bo, and this causes a shift shock.

In the above-described embodiment, the third speed to the second speed
Although the case where the downshift to the high speed is performed has been described as an example, the present invention is not limited to the above embodiment, and when the automatic transmission shown in FIG.
The present invention can also be applied to other shifts such as a downshift from the second speed to the second speed. The present invention can also be applied to a shift control device for an automatic transmission other than the automatic transmission shown in FIG. In this case, if the present invention is applied to a so-called clutch-to-clutch shift torque reduction control, it is possible to prevent the engine from rising due to a delay in clutch engagement. Further, the input torque reduction control according to the present invention can be implemented by, besides delaying the ignition timing of the engine in the above-described embodiment, reducing the fuel injection charge to reduce the engine torque, or controlling the torque converter to change the torque ratio. May be performed.

[0032]

As is apparent from the above description, according to the transmission control apparatus of the present invention, when the input torque is large and the amount of change in the number of revolutions of the rotating member accompanying the shift is small, the input torque is reduced. Since the control for reducing the speed is started earlier than in the case of another shift, a delay in engagement of the friction engagement device that is engaged to perform the shift is prevented, and as a result, a shift shock or engine blow-up occurs. And the like can be prevented beforehand and good shifting characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a block diagram showing one embodiment of the present invention.

FIG. 3 is an engagement operation table of the friction engagement device.

FIG. 4 is a flowchart showing a part of a torque down control routine during a power-on downshift from a third speed to a second speed.

FIG. 5 is a flowchart showing another portion of the routine of the torque down control at the time of the power-on downshift from the third speed to the second speed.

FIG. 6 shows the rotational speed of the clutch and the rotational speed of the second clutch, the rotational speed of the output shaft, the ignition timing, and the rotational speed of the second transmission portion during the power-on downshift from the third speed to the second speed. It is a time chart which shows each change of the oil pressure of a brake, the oil pressure of a 2nd brake, and an output shaft torque.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Friction engagement device 2 Power-on downshift detection means 3 Running state detection means 4 Torque down time setting means 5 Torque reduction means A Automatic transmission

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-6550 (JP, A) JP-A-2-86963 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 59/00-63/48

Claims (1)

(57) [Claims] 1. A shift control device for an automatic transmission in which a shift in which a friction engagement device is engaged during a shift is performed, wherein power-on for detecting a shift in which the friction engagement device is engaged during a downshift in a driving state. Downshift detection means;
Traveling state determining means for determining whether the traveling state is a traveling state in which the input torque to the automatic transmission is large and the amount of rotation change of the predetermined rotating member accompanying the downshift is small, and the traveling state determining means When it is determined that the vehicle is in a traveling state in which the input torque is large and the rotation change amount of the predetermined rotating member accompanying the downshift is small, the start timing of the control for reducing the input torque is not in the traveling state. Torque-down time setting means for setting earlier than the start time of the control for reducing the input torque when the traveling state determination means has determined the torque, and torque for reducing the input torque at the set time. A shift control device for an automatic transmission, comprising: a reduction unit.