JP2014046796A - Lockup control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lockup control device of an AT vehicle capable of achieving speedy lockup, improving fuel consumption and lessening a shock.SOLUTION: A lockup control device representatively includes a control constitution in which in off-up shifting, the turbine rotational frequency at the end of shifting is calculated from the vehicle speed, the engine rotating speed is held by an electronic throttle at a rotational frequency higher than the calculated turbine rotational frequency, and lockup is performed.

Description

The present invention relates to a lockup control device that can perform lockup speedily even when an off-up shift is performed in a lockup-off state, thereby improving fuel efficiency and reducing shock.

The lock-up mechanism is a clutch mechanism provided to improve the poor transmission efficiency of the torque converter, and aims to improve fuel efficiency and power performance by bringing the engine and transmission rotary shafts into a direct connection state. .

There is no problem if the engine speed and the input shaft speed of the transmission (hereinafter referred to as “turbine speed”) are the same or small when locking up, but if the difference between the two speeds is large, the clutch is engaged. Shock can occur. Normally, when the lockup control is performed in a state where the engine torque is large and the hydraulic pressure is present, the two rotation shafts are slowly synchronized and connected directly from a state where the engine speed is high.

However, when an off-up shift (accelerator-off and shift-up) is performed in the lock-up off state, the engine speed <the turbine speed tends to be reached at the end of the shift. Even if the accelerator is turned on and lock-up control is performed in this state, since the engine torque is small, the two rotary shafts are directly connected to each other just by slightly increasing the hydraulic pressure, resulting in a shock. Therefore, in practice, the lockup control cannot be performed when the engine rotational speed <the turbine rotational speed.

On the other hand, for example, in Patent Document 1, it is determined whether or not the engine is in a coasting state driven by a transmission, and when the engine enters a lock-up region in the coasting state, the engine speed is increased. A lock-up control configuration for an AT vehicle that performs lock-up when the number of revolutions that can be locked-up is reached is disclosed.

However, Patent Document 1 controls to increase the engine speed when the engine speed <turbine speed, but the control is actually executed after the engine speed <turbine speed. However, since the lock-up operation is slightly delayed, fuel cut cannot be performed correspondingly, and there is a problem in fuel efficiency.

Japanese Patent No. 4078789

The present invention has been created in view of the above problems, and when performing an up-up shift or the like in a lock-up off state, the engine speed at the end of the shift does not drop so much that lock-up can not be performed. An object of the present invention is to provide a lockup control device having a control configuration with high fuel efficiency.

The present invention
When the coast state is entered at the time of lock-up off, the turbine speed after shifting is calculated from the vehicle speed,
The engine speed is maintained by the engine speed increasing means at a higher speed than the calculated turbine speed, and lockup is performed.
A lockup control device having a control configuration is provided.

The present invention typically includes
At the time of off-up shifting, the turbine speed after shifting is calculated from the vehicle speed,
It has a control configuration in which the engine speed is held by an electronic throttle at a higher speed than the calculated turbine speed and lock-up is performed.

According to the present invention, the engine speed is increased before the engine speed falls below the turbine speed after the off-up shift, so that the lockup cannot be performed and speedy lockup is possible, and fuel consumption is improved. Shock can be reduced.

In particular, the lockup control device of the present invention can calculate the amount of increase in the engine speed from the vehicle speed (proportional to the turbine speed), so the engine speed is increased before the actual engine speed <turbine speed. It is greatly advantageous that lockup can be performed.

It is a timing chart example which shows the engine speed and turbine speed at the time of the off-up shift controlled by the lockup control device of the present invention. It is a schematic block diagram which shows the electric control system regarding the lockup control apparatus of this invention. It is a flowchart which shows the control structural example in this lockup control apparatus.

Hereinafter, a lockup control device according to an embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a timing chart showing an engine speed and a turbine speed at the time of an off-up shift controlled by this lockup control device, and will be described below with reference to this.

The vertical axis in FIG. 1 indicates the rotational speed (rpm) of the engine and the turbine, and the horizontal axis indicates time (sec). In addition, (1) indicates the engine speed, and (2) indicates the turbine speed. The off-up in FIG. 1 is a case where the accelerator is turned off to shift up from the third speed to the fourth speed. It is large before the off-up shift, and it can be seen that engine speed (1)> turbine speed (2). In the case of FIG. 1, there is a difference between the engine speed and the turbine speed. This is because the engine rotation is input to the turbine while sliding with the torque converter. Here, the transmission difference from the engine speed (1) to the turbine speed (2) is about 200 rpm.

The off-up shift is started around time A. Since the accelerator is returned from time A to time B, the engine speed (1) decreases. Then, the shift-up from the 3rd speed to the 4th speed is started at time B, and then it becomes a coast state and both the turbine speed (2) and the engine speed (1) decrease. In FIG. 1, (3) shows the turbine speed at the third speed, and (4) shows the turbine speed at the fourth speed. The turbine speed (3) at the third speed and the turbine speed (4) at the fourth speed are values calculated from the vehicle speed. For example, it is calculated by the number of rotations of the tire × the differential gear ratio × the gear ratio.

The turbine rotational speed (2) decreases, but when the turbine rotational speed (4) at the fourth speed is reached at time C, the value (4) becomes constant. On the other hand, the engine speed (1) is inherently further reduced after the time C as indicated by the dotted line (5), and the engine speed (1) <the turbine speed (2). This is because the rotation transmission by the torque converter is slippery because it is not locked up (in the coast state, the engine rotates following the turbine rotation).

Even if you try to lock up in this state, the engine torque is originally low, so the direct connection reaction of the rotating shaft is very sensitive, and if you raise the hydraulic pressure even a little, the rotating shaft will be connected directly and a shock will occur To do. Therefore, lockup cannot be performed in a state where engine speed (1) <turbine speed (2). On the other hand, when the engine torque is large and the engine speed is high, the lockup can be performed without any problem.

Therefore, in the lockup control device of the present invention, the engine speed is controlled to be increased by the electronic throttle before the engine speed (1) falls below the turbine speed (2). As is apparent after time C in FIG. 1, when the engine speed (1) approaches the turbine speed (4) at the fourth speed, the electronic throttle is controlled to increase the speed. In the case of FIG. 1, the engine speed is increased by about 50 to 100 rpm (see the rotational speed (6)).
Next, a specific control configuration example in the lockup control device will be described.

FIG. 2 is a schematic block diagram showing an electric control system related to the lockup control device. Reference numeral 1 denotes an ECU (electronic control unit) composed of a microcomputer, which is shown here as a concept of integrating an engine ECU and a transmission ECU. The ECU 1 receives signals from the engine speed sensor 2, the turbine speed sensor 3, and the throttle opening sensor 4. Further, an engine speed increasing means (for example, an electronic throttle) 5 and a linear solenoid valve SLU6 are connected to the ECU 1 in order to drive and control a hydraulic servo of a lockup clutch (not shown). In this lockup control device, the ECU 1 controls the electronic throttle 5 to a desired throttle opening degree to increase the engine speed when the engine speed decreases to a predetermined value while detecting the engine speed and the turbine speed. , SLU locks up.

Referring to FIG. 3, it is a flowchart showing an example of control in the lockup control device.
This lock-up control is premised on being in a lock-up off state. First, the ECU 1 determines whether or not the accelerator is off based on a signal from the throttle opening sensor 4 (STEP 1). Then, the ECU 1 starts the shift driving based on the shift diagram or the like (STEP 2). As a result, the turbine speed (2) decreases as shown in FIG.

When the start of the off-up shift is confirmed, the turbine speed R4 after the upshift is calculated and set (STEP 3). Here, as shown in FIG. 1, the speed is changed from the third speed to the fourth speed, and the turbine rotational speed R4 means the turbine rotational speed (4) shown in FIG. The turbine speed R4 is, for example,
R4 = Tire rotation speed x differential gear ratio (fixed) x 4-speed gear ratio (fixed)
R4 is set as a threshold value.

Further, the engine speed increase amount R6-R4 is also calculated and set (STEP 4). As described above, this is to increase the engine speed so that the engine speed does not drop below the turbine speed R4. The amount of increase R6-R4 is the engine speed (6) -turbine speed ( Same as 4). In this case, R6-R4 = 50 to 100 rpm is set.

When the increase amount R6-R4 of the engine speed is calculated, the electronic throttle 5 is operated (STEP 5), and the engine speed increases. Thereafter, when the conditions for enabling lock-up are satisfied (STEP 6), the implementation of lock-up is permitted (STEP 7). When actually performing lockup, the SLU 6 is operated.

As mentioned above, although embodiment and the concept about the lockup control device of the present invention have been described, the present invention is not limited to this, and the scope does not depart from the spirit and teaching described in the claims and the description. It will be understood by those skilled in the art that other variations and improvements can be obtained.

The present invention executes control to increase the engine speed before the engine speed decreases below the turbine speed after the off-up shift. For this reason, the present invention enables speedy lockup, and can be used as a lockup control device capable of improving fuel consumption and reducing shock.

1 ECU (electronic control unit)
2 Engine speed sensor 3 Turbine speed sensor 4 Throttle opening sensor 5 Engine speed increasing means (electronic throttle)
6 SLU

Claims (1)

At the time of off-up gear shifting in the lock-up off state, the turbine speed after shifting is calculated from the vehicle speed,
The engine speed is maintained by the engine speed increasing means at a higher speed than the calculated turbine speed, and lockup is performed.
Lock-up control device having control structure