JP2002039353A - Control device for automatic transmission - Google Patents

Abstract

(57) [Problem] To provide a control device for an automatic transmission capable of shortening a time required from an automatic stop state of an engine to a start and preventing a driver from feeling uncomfortable due to a delay in start. A lock mechanism (8) for fixing a turbine shaft (2) of an automatic transmission is provided, and when the engine is automatically started, a starting frictional engagement element (3a) is engaged with the lock mechanism (8) fixing the turbine shaft (2). After the start of the operation, the lock mechanism 8 is released. Since the starting frictional engagement element 3a is engaged in a state where there is no input / output rotation difference, no shock is generated even if the engagement is suddenly performed, and the starting frictional engagement is immediately performed without waiting for completion of engine start. The engagement of the element 3a can be started, and the engagement can be performed at the maximum speed without performing the precise slip control, whereby the starting frictional engagement element 3a completes the engagement early and can start.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission applied to an idle stop vehicle.

[0002]

2. Related Art Generally, in a planetary gear type automatic transmission (A / T) and a belt type automatic transmission (CVT), N
By engaging the starting clutch with the switching from the range to the D range, power transmission from the input shaft side to the output shaft side is started to prepare for starting. At this time, the clutch is gently engaged by controlling the slip amount according to a predetermined procedure, thereby preventing the occurrence of a shock due to sudden power transmission.

On the other hand, in recent years, idle stop vehicles have been put into practical use in which the engine is temporarily stopped at a traffic light or the like to improve fuel efficiency and reduce emissions. For example, as described in Japanese Patent Application Laid-Open No. 9-310629, when an automatic transmission is combined with this type of idle stop vehicle, the vehicle speed = 0 km / h when traveling in the D range (travel range). The engine is stopped when predetermined engine stop conditions such as accelerator off and brake on are satisfied, and when the driver turns off the brake from that state, the engine is started assuming that the engine start conditions are satisfied. Let me.

[0004]

Since the oil pressure for operating the clutch of the automatic transmission is generated by using the engine rotation, the oil pressure is reduced during the above-mentioned automatic engine stop, and the oil pressure falls to the D range. Nevertheless, the starting clutch is released naturally. Therefore, in order to start the vehicle from that state, after starting the engine and raising the oil pressure,
It is necessary to engage the starting clutch.

If the clutch is merely engaged, it is conceivable to start the clutch engagement operation in the middle of the start when the hydraulic pressure has risen to some extent. Since it is necessary to precisely control the slip amount, the clutch engagement cannot actually be started until after the start of the engine is completed and the rotation input to the transmission is sufficiently stabilized. Therefore, after the driver turns off the brake, the vehicle will not start until at least the time required for starting the engine and the time required for engaging the clutch have elapsed.

[0006] In an idle stop vehicle in which the engine start is automated, the driver at this time only steps from the brake to the accelerator for starting, so that the clutch engagement is completed and acceleration is actually started. However, there is a problem that the acceleration delay time of the vehicle is felt to be very long, which eventually impairs the commercial value of the idle stop vehicle. SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic transmission that can shorten the time required from the automatic stop state of the engine to the start of the vehicle, prevent the driver from feeling uncomfortable due to the delay of the start, and thereby improve the commercial value of the idle stop vehicle. It is to provide a control device.

[0007]

In order to achieve the above object, according to the present invention, an engine is stopped when a predetermined stop condition is satisfied when a vehicle having an automatic transmission in a travel range is stopped, and a predetermined start condition is established. Means for starting the engine when the condition is satisfied, a lock mechanism for fixing the turbine shaft of the automatic transmission, a starting frictional engagement element engaged when the automatic transmission starts, and an automatic engine stop / start. And starting control means for engaging the starting frictional engagement element in a state where the turbine shaft of the automatic transmission is fixed by the lock mechanism when the engine is started by the means, and releasing the lock mechanism after the start of the engine is completed.

Accordingly, since the starting frictional engagement element is engaged in a state where there is no rotation difference between the turbine shaft and the output shaft by fixing the turbine shaft, no shock is generated even if the engagement is suddenly performed. As a result, the engagement of the starting frictional engagement element can be started immediately without waiting for the completion of the engine start, and the engagement can be performed at the maximum speed without performing the precise slip control. And the vehicle can be started.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a control device for a planetary gear type automatic transmission will be described below.
FIG. 1 is an overall configuration diagram showing a control device of an automatic transmission according to the present embodiment. In this figure, a schematic configuration of an upper half from a rotation center of the automatic transmission is shown. The automatic transmission is configured for an FR vehicle. An engine (not shown) is located on the left side of the figure, and a pump impeller 1a of a torque converter (hereinafter abbreviated as a torque converter) 1 is rotationally driven together with its flywheel. Rotation of pump impeller 1a is torque converter 1.
The power is transmitted to the turbine runner 1b via an ATF (automatic transmission fluid) filled therein, and together with the turbine runner 1b, the turbine shaft 2 and each clutch 3 indicated by a thick line in the drawing are integrally rotated.

The turbine shaft 2 is selectively connected to each of the elements (not shown) of the planetary gear mechanism 4 (sun gear, planetary gear, ring gear, carrier, etc.) via these clutches 3. The rotation of each element is selectively restricted by the brake 5. The planetary gear mechanism 4 is connected to driving wheels (rear wheels) via a right output shaft 6 in the figure, a propeller shaft (not shown), a differential gear, and the like. Each clutch 3 and brake 5 are actuated by hydraulic oil from an oil pump built in the transmission,
This oil pump is driven using input rotation from an engine. The operation state of the planetary gear mechanism 4 is switched according to the engagement state of each clutch 3 and the brake 5, and power is transmitted from the turbine shaft 2 to the output shaft 6 with the corresponding rotation direction and speed ratio, and the drive wheels are driven. Is driven to rotate.

The clutch 3a, which is one of the clutches 3, functions as an under drive clutch (hereinafter referred to as a U / D clutch) as a starting frictional engagement element. For example, when the shift position is switched from the N range to the D range, the solenoid 7 connected to the U / D clutch 3a is controlled to increase the duty ratio from 0% to 100% according to a predetermined control procedure, and accordingly, is controlled in the increasing direction. Upon receiving the supplied hydraulic oil, U / D clutch 3a is gently engaged, and power transmission from turbine shaft 2 to output shaft 6 is started. Although not shown in the drawing, the other clutches 3
Also, the engagement state of the brake 5 is individually controlled by the solenoid.

On the other hand, the turbine shaft 2 is connected to a transmission housing via a turbine lock brake 8 as a lock mechanism. When the turbine lock brake 8 is locked (engaged) by an actuator 9, the turbine shaft 2 is rotated. In addition, the rotation of the turbine runner 1b is restricted. Incidentally, the turbine lock brake 8 in the normal state is released (released). As a specific configuration of the turbine lock brake 8, for example, a band brake is wound around the outer periphery of the turbine shaft 2, one end of which is fixed to the housing, and the other end is connected to the actuator 9. When the band brake is fastened by the actuator 9, friction occurs between the inner circumference of the band brake and the outer circumference of the turbine shaft 2, and the rotation of the turbine shaft 2 is regulated. Further, the turbine lock brake 8 may be configured in the same manner as a parking brake for an automatic transmission. In this case, a claw is hooked by an actuator 9 on irregularities formed on the outer periphery of the turbine shaft 2. , Restricts the rotation of the turbine shaft 2.

On the other hand, an input / output device (not shown), storage devices (ROM, RAM, etc.) for storing control programs and control maps, and a central processing unit (CP)
U), an ECU (electronic control unit) 11 including a timer counter and the like is provided. The input side of the ECU 11 includes an accelerator sensor 12 for detecting an accelerator operation amount by a driver, a vehicle speed sensor 13 for detecting a vehicle speed, a brake oil pressure sensor 14 for detecting a brake oil pressure generated by a brake operation by the driver, and the like. Sensors are connected. On the output side of the ECU 11, a throttle motor 15 for opening and closing the throttle valve of the engine, a starter 16 for cranking the engine, the U /
The solenoid 7 of the D clutch 3a, the actuator 9 of the turbine lock brake 8, and the like are connected.

The ECU 11 executes fuel injection control and ignition timing control of the engine, and shift control of the automatic transmission. In addition, based on the accelerator operation amount detected by the accelerator sensor 12, the throttle motor 15 is controlled according to a preset map. To control the opening of the throttle valve. Further, the ECU 11 executes an idle stop control for temporarily stopping the engine when the vehicle is stopped (automatic engine stop and start means). When starting the automatically stopped engine, the ECU 11 disconnects the U / D clutch 3a of the transmission. U / D clutch engagement control for quick engagement is performed (start control means).

Therefore, first, the outline of the idle stop control will be described, and then the U / D clutch engagement control performed in connection therewith will be described. The engine stop by the idle stop control is performed when a preset engine stop condition is satisfied. In the present embodiment, it is considered that the engine stop condition is satisfied when all of the following three requirements are satisfied.

1) The vehicle speed is 0 km / h. 2) The accelerator operation amount is 0 (accelerator off). 3) The brake oil pressure is equal to or more than a predetermined value (brake on). When the vehicle is stopped, the engine stop condition is satisfied, and the ECU 11 stops the fuel injection control and the ignition timing control to stop the engine.

While the engine is stopped, the ECU 11
Determines whether a preset engine start condition is satisfied. In the present embodiment, when the brake oil pressure decreases at a predetermined rate or more from the state in which the engine stop condition is satisfied as described above, it is determined that the engine start condition is satisfied, assuming that there is an intention to start the vehicle. . At this time, the ECU 11 restarts the fuel injection control and the ignition timing control of the engine and operates the starter 16. As a result, the engine is cranked and started, and it becomes possible to cope with the subsequent start.

While the engine is stopped, the shift position remains in the D range. However, since the oil pump is not driven, the oil pressure in the transmission decreases, and the U / D clutch 3a is naturally released. Therefore, in order to start the vehicle from that state, it is necessary to start the engine, raise the oil pressure, and engage the U / D clutch 3a. Therefore, the ECU 11 executes U / D clutch engagement control for controlling the U / D clutch 3a, the turbine lock brake 8, and the like at the timing shown in the time chart of FIG.

Hereinafter, the details of the U / D clutch engagement control will be described. First, at the time when the engine is stopped, the turbine lock brake 8 is locked by the actuator 9 in advance, whereby the rotation of the turbine shaft 2 is restricted. .
Then, when the driver steps from the brake to the accelerator for starting, the engine start condition is satisfied with a decrease in the brake oil pressure (point a in FIG. 2). At this time, the ECU 11 starts the process for starting the engine such as the starter operation as described above, while the solenoid 7
Is controlled to 100%.

Since the turbine runner 1b is locked together with the turbine shaft 2, cranking is performed while the torque converter 1 is slipped. Then, with the start of cranking, the hydraulic pressure supplied to the U / D clutch 3a gradually increases together with the engine rotation speed,
The / D clutch 3a starts operating in the engagement direction before the engine completely explodes. As described above, the hydraulic oil is supplied at full pressure based on the duty ratio of 100%. At this time, the U / D clutch 3a operates on the engagement side at the maximum possible speed on the basis of the supply hydraulic pressure at that time. Is switched to

Here, as described above, in the conventional example, in order to suppress a shock at the time of engagement due to a difference in rotation between the input and output of the clutch, it is necessary to gently engage the clutch and to reduce the slip amount. For precise control, the engagement could not be started until the start of the engine was completed and the rotation was stabilized. On the other hand, in the present embodiment, the rotation of the turbine shaft 2 is restricted by the turbine lock brake 8 as described above, and the rotation of the output shaft 6 is also stopped by stopping the vehicle. The rotational difference between the input and output of the clutch 3a is 0, and no shock is generated even when the clutch 3a is suddenly engaged. Therefore, the engagement can be started at the same time as the cranking start without waiting for the completion of the engine start as in the conventional example, and the engagement can be performed at the maximum speed with the duty ratio of 100% without performing the precise slip control.

On the other hand, the accelerator operation by the driver is started in parallel with this (point b in FIG. 2), but the ECU 11 at this time sets the throttle opening to 0 (idle equivalent value) regardless of the accelerator operation amount. Keep holding. Meanwhile, the engine completely explodes and completes the start (point c in FIG. 2),
Thereafter, the supply oil pressure of the U / D clutch 3a reaches a specified value (adjustment pressure by the pressure adjustment valve) (point d in FIG. 2).
In other words, at this point, the U / D clutch 3a has already been engaged, and it can be assumed that the U / D clutch 3a can sufficiently withstand the torque transmission at the time of starting.

The ECU 11 releases the turbine lock brake 8 with the actuator 9 after a preset release standby time T1 has elapsed (point e in FIG. 2). Thereby, the regulation of the rotation of the turbine shaft 2 is stopped, and power transmission from the turbine shaft 2 to the output shaft 6 is started. Due to the suppression of the throttle opening described above, the engine at this time generates only a small torque due to idling operation.
The shock at the moment of starting the power transmission is negligible, and the driver does not feel uncomfortable.

Thereafter, when a preset acceleration standby time T2 elapses, the ECU 11 starts controlling the throttle valve to open at a predetermined rate of change (point f in FIG. 2), and finally the throttle valve corresponding to the accelerator operation amount. The opening degree is controlled, and the vehicle starts. As described above, in the present embodiment, the turbine shaft 2
U / D with no rotation difference between input and output
In order to engage the clutch 3a, the shock at the time of engagement is prevented, and the U / D clutch 3a is engaged at the maximum speed at the same time as the cranking starts.

At this time, from the point b at which the accelerator operation is started, the driver starts the vehicle and starts to actually experience the acceleration G (for example, in FIG.
2G) is felt as the acceleration delay time S. However, since the U / D clutch 3a completes the engagement promptly as described above, the subsequent throttle opening control is also performed early. Therefore, the point g at which the driver experiences the acceleration G is much earlier than in the conventional example. Therefore, according to the control device for an automatic transmission of the present embodiment, the time required from the automatic stop state of the engine to the start can be shortened, and the driver's uncomfortable feeling due to the delay of the start can be prevented. Can be improved.

Although the embodiment has been described above, aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the control device is applied to a planetary gear type automatic transmission, but the type of the automatic transmission is not limited to this, and for example, a control device for a belt type automatic transmission (CVT) It may be embodied as Also in this CVT, when starting from the engine automatic stop state, the forward clutch corresponding to the U / D clutch 3a of the above embodiment is engaged, so that the same control as in the embodiment is applied to start the vehicle. The time required until can be shortened.

In the above embodiment, the turbine lock brake 8 is locked when the engine is stopped. However, the timing is not limited to this. For example, when the engine start condition is satisfied, the cranking or the U / D clutch engagement is stopped. The lock may be performed prior to the start of the case. Further, in the above-described embodiment, the vehicle stop speed is set to 0 km / h, the accelerator is turned off, and the brake is turned on as the engine stop condition. When the brake oil pressure is reduced from that state, it is considered that the engine start condition is satisfied. The condition is not limited to this. For example, the engine start condition may be determined based on a change in the brake stroke.

[0028]

As described above, according to the control apparatus for an automatic transmission of the present invention, the time required from the automatic engine stop state to the start can be shortened, and the driver's uncomfortable feeling due to the delay of the start can be prevented. As a result, the commercial value of the idle stop vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a control device for an automatic transmission according to an embodiment.

FIG. 2 is a time chart showing a control situation when starting from an engine automatic stop state.

[Explanation of symbols]

2 Turbine shaft 3a U / D clutch (friction engagement element for starting) 8 Turbine lock brake (lock mechanism) 11 ECU (automatic engine stop / start means, start control means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 29/02 321 F02D 29/02 321A 41/04 330 41/04 330G F02N 15/00 F02N 15/00 E // F16H 59:18 F16H 59:18 59:44 59:44 59:54 59:54 F term (reference) 3D041 AA30 AA66 AB01 AC01 AC08 AC15 AC18 AD10 AD41 AD51 AE04 AE07 AE09 AE32 AE38 AE39 AE40 AF00 3G092 BB10 DE01S EA09 EA14 EA17 FA GB01 GB10 HA06X HC08X HF08Z HF21Z HF26Z 3G093 AA05 AA06 BA15 BA19 BA21 BA22 CB05 DA06 DB05 DB11 DB15 EA05 EA09 EA13 EB02 FB05 3G301 HA01 JA02 JA03 KA01 KB01 LB02 MA11 PA11Z PF01 MA03 NA01 PN01 MA02 UA07 VB01W VD02W VD11W

Claims (1)

[Claims] An automatic engine stop and start means for stopping an engine when a predetermined stop condition is satisfied when a vehicle in which the automatic transmission is in a travel range is stopped and for starting the engine when a predetermined start condition is satisfied; A lock mechanism for fixing a turbine shaft of the automatic transmission, a starting frictional engagement element that is engaged when the automatic transmission starts, and an automatic shift by the lock mechanism when the engine is started by the automatic engine stop and start means. A start control means for engaging the starting friction engagement element in a state where the turbine shaft of the engine is fixed, and releasing the locking mechanism after the start of the engine is completed. .