JP4655577B2 - Shift control device for automobile - Google Patents

Description

  The present invention relates to a shift control apparatus for an automobile that performs rotation synchronization control that synchronizes an engine rotation speed with a rotation speed on the input side of a transmission during downshifting of an automatic transmission.

When downshifting is performed with an automatic transmission, such as when decelerating, the gear ratio increases, so it is necessary to increase the engine speed. In this case, by releasing the clutch of the high speed side gear and engaging the clutch of the low speed side gear, the engine speed is increased from the output side of the transmission, and the ratio of the vehicle speed and the engine speed is the gear ratio. The gear shift is completed at the balanced position.
However, if the engagement time of the low-speed gear clutch is too short, the inertia torque on the engine side is rapidly transmitted to the drive wheels, causing a shift shock, so it is necessary to take a long engagement time to avoid this, Therefore, the shift time cannot be shortened.

Therefore, as shown in Patent Document 1, at the time of downshift, before the clutch of the low speed side gear is engaged, the engine torque is increased and the rotation is blown up, thereby shortening the shift time and after the shift. It is known to reduce the shift shock in synchronization with the rotational speed that balances the gear ratio.
JP-A-5-229368

  However, when the engine speed reaches the synchronous rotational speed that matches the gear ratio after the shift, the rotational synchronous control is terminated, and the target engine torque is returned from the rotational synchronous torque to the driver request torque (accelerator instruction torque). Therefore, when the synchronous rotation speed is reached, the rotation synchronization control ends and the clutch of the gear after shifting is engaged. Since it is fastened at a low rotational speed, there is a problem that a shift shock occurs.

  In view of such problems, an object of the present invention is to make it possible to reduce a shift shock even when there is a delay in the increase in the hydraulic pressure of the engagement clutch after the rotation synchronization control.

  Therefore, in the present invention, after the engine rotation speed reaches the synchronous rotation speed and the engagement operation of the clutch of the gear stage after the shift is started, the driver requested torque based on the accelerator opening amount for a predetermined torque up time. In addition, a predetermined torque increase amount for maintaining the engine rotational speed at the synchronous rotational speed is added to determine a target engine torque, and the target engine torque is controlled.

According to the present invention, since the engine torque for maintaining the synchronous rotational speed is output even after the engine rotational speed reaches the synchronous rotational speed, the synchronous rotational speed is maintained even during the response delay of the engagement clutch. Can prevent shift shock.
In addition, after the engine speed reaches the synchronous speed, the driver's requested torque is reflected as open control instead of feedback control, so the time during which the driver becomes insensitive to the accelerator operation can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of an automobile transmission control apparatus (cooperative control apparatus for an engine and an automatic transmission) showing an embodiment of the present invention.
An engine (internal combustion engine) 1 mounted on an automobile is provided with an electrically controlled throttle valve 3 for controlling an intake air amount in an intake passage 2 thereof, and an opening degree thereof is controlled by an engine control unit (ECU) 4. Although illustration and description of the fuel supply system of the engine 1 are omitted, the supplied fuel amount is controlled by the ECU 4 so that a desired air-fuel ratio is obtained with respect to the intake air amount.

  An automatic transmission 5 is provided on the output side of the engine 1. The automatic transmission 5 includes a torque converter 6 with a lock-up clutch connected to the output shaft of the engine 1, a stepped transmission (gear mechanism) 7 connected to the output side of the torque converter 6, And a hydraulic control mechanism 8 for engaging / disengaging various transmission elements (such as a clutch) in the machine 7. The hydraulic control mechanism 8 (specifically, a shift solenoid that controls the hydraulic pressure to various shift elements to perform a shift operation) is controlled by an automatic transmission control unit (ATCU) 9.

Signals are input to the ECU 4 and the ATCU 9 from various sensors.
The accelerator opening sensor 10 detects an accelerator pedal depression amount (accelerator opening) APO and outputs a corresponding signal.
The crank angle sensor 11 outputs a signal synchronized with the rotation of the crankshaft, and can detect the engine speed Ne from this signal.

The vehicle speed sensor 12 detects a vehicle speed (output shaft rotation speed of the transmission 7) VSP and outputs a corresponding signal.
Moreover, ECU4 and ATCU9 are connected by the communication line 13, and cooperative control is possible by sharing sensor detection information and internal control information.
Here, in ATCU9, in the automatic shift mode, the target gear stage (shift stage) is set according to the accelerator opening APO and the vehicle speed VSP, and in the manual shift mode, according to the shift operation of the driver. In comparison with this gear stage, it is determined whether or not there is a shift request, and a shift operation is performed when there is a shift request.

  The ECU 4 determines the driver required torque based on the accelerator opening APO (and the engine speed Ne), and normally (during non-shifting), the target engine torque tTe = driver required torque. Based on the target engine torque tTe (and the engine speed Ne), a target throttle opening tTVO for obtaining this is calculated, and the opening of the electric throttle valve 3 is controlled according to the target throttle opening tTVO.

On the other hand, at the time of shifting, particularly during downshifting, the ECU 4 performs coordinated control with the ATCU 9 when calculating the target engine torque tTe.
The cooperative control (calculation of the target engine torque tTe) between the ECU 4 and the ATCU 9 during the downshift will be described with reference to the flowchart of FIG.
The flow in FIG. 2 is mainly performed by the ECU 4 in order to calculate the target engine torque tTe in response to a downshift request, and the control on the ATCU 9 side is indicated by a dotted line block.

In S1, in response to the downshift request, the clutch of the gear stage (high speed side gear) before the shift is released on the ATCU 9 side to be in the neutral state.
In S2, in order to synchronize the engine speed with the speed on the transmission input side after the shift, the speed on the transmission input side after the shift is detected from the vehicle speed VSP and the gear ratio after the shift while detecting the vehicle speed VSP. The target synchronous rotation speed Ns corresponding to is calculated.

In S3, the target engine torque tTe is calculated so that the actual engine speed Ne (actual engine speed) Ne is detected and the actual engine speed Ne matches the target synchronous engine speed Ns.
Specifically, a deviation (Ns−Ne) between the target synchronous rotation speed Ns and the actual rotation speed Ne is obtained, a proportional torque P × (Ns−Ne) based on this deviation, and a differential component for suppressing overshoot. The torque D × dNe / dt is obtained, and the target engine torque tTe is updated by adding the proportional torque to the current target engine torque tTe and subtracting the differential torque.

tTe = tTe previous value + P × (Ns−Ne) −D × dNe / dt
When the target engine torque tTe is obtained, the target throttle opening tTVO for obtaining the target engine torque tTe (and the engine speed Ne) is calculated, and the electric throttle valve 3 of the electric throttle valve 3 is calculated according to the target throttle opening tTVO. Control the opening.
In S4, the actual rotational speed Ne is compared with the target synchronous rotational speed Ns, and it is determined whether or not the actual rotational speed Ne has reached the target synchronous rotational speed Ns (Ne ≧ Ns). That is, it is determined whether or not the engine speed Ne is synchronized with the speed on the transmission input side after the shift.

If Ne <Ns, the process returns to S2 and S3 to continue the rotation synchronization control.
When Ne ≧ Ns, the process proceeds to S5.
In S5, on the ATCU9 side, the clutch of the gear stage (low speed side gear) after the shift is engaged (engagement operation is started).
In S6, a torque up time and a torque up amount during the fastening operation are calculated.

The torque-up time corresponds to the time until the engagement of the clutch of the gear stage after the shift, and the engagement delay time varies depending on the engine speed Ne and the gear stage (shift type) after the shift. Let
That is, for each gear position after the shift (1st speed, 2nd speed, 3rd speed, etc., 2 → 1 shift, 3 → 2 shift, 4 → 3 shift, etc.), the torque up time is determined according to the engine speed Ne. The torque up time is set with reference to this table. Specifically, the higher the engine speed Ne, the longer the fastening delay time, so the torque up time is set longer. . Further, between the tables for each post-shift gear stage, the engagement delay time becomes longer as the post-shift gear stage is at a lower speed side, so the torque up time is lengthened.

The amount of torque increase is to overcome the friction of the engine etc. and maintain the engine rotation speed Ne at the synchronous rotation speed. Since the friction varies depending on the engine rotation speed Ne and the post-shift gear stage (transmission type), Change accordingly.
That is, the amount of torque increase in accordance with the engine speed Ne for each post-shift gear stage (1st speed, 2nd speed, 3rd speed, etc., 2 → 1 speed change, 3 → 2 speed change, 4 → 3 speed change ...). The torque increase amount is set with reference to this table. Specifically, the higher the engine speed Ne, the greater the friction, so the torque increase amount is set larger. Further, between the tables for each post-shift gear stage, the friction increases as the post-shift gear stage is at a lower speed side, so the amount of torque increase is increased.

In S7, the target engine torque tTe is calculated by adding the torque increase amount to the driver request torque based on the accelerator opening.
When the target engine torque tTe is obtained, a target throttle opening tTVO for obtaining the target engine torque tTe (and the engine speed Ne) is calculated, and the electric throttle valve 3 is controlled according to the target throttle opening tTVO. Control the opening.

In S8, it is determined whether or not the torque up time has elapsed.
If it is within the torque up time, the process returns to S7 to continue the torque up control (synchronous rotation speed maintenance control).
When the torque up time has elapsed, the process proceeds to S9 and shifts to normal control. Therefore, thereafter, the target engine torque is set to the driver required torque, and the opening degree of the electric throttle valve 3 is controlled so as to realize the driver required torque based on the accelerator opening degree.

FIG. 3 is a control block diagram showing the flow of FIG.
Synchronization determination by the synchronization determination circuit 101 is started by a rotation synchronization request signal at the time of downshift from the ATCU. When Ne <Ns, the output of the synchronization determination circuit 101 is “1” and the first changeover switch 102 is “ Since the output of the OFF delay circuit 103 is also “1”, the second changeover switch 104 is also switched to the “1” side.

In this state, the rotation synchronization torque calculation circuit 105 calculates the rotation synchronization torque from the P gain and the D gain based on the rotation speed deviation (Ns−Ne), and this changes the first and second changeover switches 102 and 104. And output as the target engine torque.
After the rotation synchronization (Ne ≧ Ns), the output of the synchronization determination circuit 101 becomes “0” and the first changeover switch 102 is switched to the “0” side, but the output of the OFF delay circuit 103 is switched by the OFF delay circuit 103. Is maintained at “1” for a predetermined time (predetermined torque up time), and the second changeover switch 104 is maintained at the “1” side.

In this state, the adder 106 adds the driver request torque and the synchronous rotation maintaining torque (predetermined torque increase amount), and this added value is sent to the target engine via the first and second changeover switches 102 and 104. Output as torque.
When a predetermined torque up time has elapsed, the output of the OFF delay circuit 103 becomes “0”, and the second changeover switch 104 is switched to the “0” side.

In this state, only the driver request torque is output as the target engine torque via the second changeover switch 104.
Next, the effect of this embodiment is demonstrated.
Referring to FIG. 4, at the time of downshift, the clutch of the gear stage before the shift is released to be in the neutral state, and the engine torque is fed back so that the engine speed is synchronized with the speed on the transmission input side after the shift. By controlling and engaging the clutch of the gear stage after the shift after synchronizing the engine speed, the shift shock can be reduced.

However, when the engine rotational speed reaches the synchronous rotational speed, the rotational synchronous control is terminated, and when the target engine torque is returned from the rotational synchronous torque to the driver request torque (accelerator instruction torque) as shown by a dotted line in FIG. The engine rotational speed decreases during the engagement delay of the clutch of the gear after the shift, and a shift shock due to a rotational deviation occurs at the time of engagement.
Therefore, in this embodiment, after the engine speed reaches the synchronous speed and the engagement operation of the clutch of the gear stage after the shift is started, as shown by a solid line in FIG. The target engine torque is determined by adding a predetermined torque increase amount corresponding to the friction for maintaining the engine speed at the synchronous speed to the driver required torque based on the accelerator opening, and the target engine torque is controlled.

Thus, even after the engine speed reaches the synchronous speed, the engine speed corresponding to the friction for maintaining the synchronous speed is output, so that the synchronous speed is maintained even during the response delay of the engagement clutch. Can prevent shift shock.
In addition, after the engine speed reaches the synchronous speed, the driver's requested torque is reflected as open control instead of feedback control, so the time during which the driver becomes insensitive to the accelerator operation can be reduced. In other words, during the rotation synchronization control, even if there is an accelerator operation by the driver, this is ignored. However, if a torque corresponding to a predetermined torque increase amount is added, The required torque can be reflected in the target engine torque, and control in consideration of the accelerator operation is possible.

Further, according to the present embodiment, the torque up time corresponding to the time until the engagement of the clutch of the post-shift gear stage is completed (engagement delay time) is determined by the engine speed and the post-shift gear stage. By variably setting, optimal control becomes possible.
Further, according to the present embodiment, the amount of torque increase for maintaining the simultaneous rotational speed is determined by the engine rotational speed and the post-shift gear stage. Is possible. Furthermore, the torque-up amount may be gradually decreased with time so as to match the movement of the clutch that is gradually engaged, or may be gradually decreased from the middle as a constant amount at the beginning. Also good.

  In the present embodiment, the throttle opening for controlling the engine torque is controlled. However, finer control may be made possible by using ignition timing control with good response.

1 is a system diagram of a shift control apparatus for an automobile showing an embodiment of the present invention Flow chart of cooperative control during downshift Control block diagram of cooperative control Coordinated control time chart

Explanation of symbols

1 engine
2 Intake passage
3 Electric throttle valve
4 ECU
5 Automatic transmission
6 Torque converter
7 Transmission
8 Shift control mechanism
9 ATCU
10 Accelerator position sensor
11 Crank angle sensor
12 Vehicle speed sensor
13 Communication line

Claims (5)

When the automatic transmission is downshifted, the clutch of the gear stage before the shift is released to the neutral state, and the engine torque is feedback-controlled so that the engine speed is synchronized with the speed of the transmission input side after the shift. In the automotive gearshift control device that shifts by engaging the clutch of the gear stage after the shift after synchronizing the engine speed,
In order to maintain the engine speed at the synchronized rotation speed after the synchronization by the synchronization even if the driver's accelerator operation is not performed in the driver requested torque based on the accelerator opening for a predetermined torque up time after the clutch engagement operation is started. A predetermined gear-up amount is added to determine a target engine torque, and control is performed to the target engine torque.   2. The shift control apparatus for an automobile according to claim 1, wherein the predetermined torque up time is variably set based on at least the engine speed.   3. The shift control apparatus for an automobile according to claim 1, wherein the predetermined torque up time is variably set based on at least the gear stage after the shift.   The shift control apparatus for an automobile according to any one of claims 1 to 3, wherein the predetermined torque increase amount is variably set based on at least the engine speed.   5. The shift control apparatus for an automobile according to claim 1, wherein the predetermined torque increase amount is variably set based on at least a gear stage after a shift.

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