JP5550893B2 - How to restart an engine with an idle stop system - Google Patents

Description

  The present invention relates to a method for restarting an engine equipped with an idle stop system.

  In recent years, the number of vehicles equipped with an idle stop system has been increasing to prevent unnecessary idling of vehicles from the viewpoint of energy saving and environmental conservation, and they are already widely used for medium and large route buses. .

  In vehicles equipped with this kind of idle stop system, the engine is automatically stopped even when the vehicle is stopped for a relatively short time, such as waiting for a signal, and the engine is restarted when starting. The engine is automatically stopped when the brake pedal is depressed when the vehicle is stopped and the vehicle speed becomes zero, and then when the foot is removed from the brake pedal, the engine is restarted and the torque converter The oil pump built in the torque converter generates hydraulic pressure and the clutch is connected, and the vehicle is started by depressing the accelerator pedal.

  As prior art document information related to this type of idle stop system, there is the following Patent Document 1.

JP 2004-353777 A

  However, in such a conventional idle stop system, the clutch is not connected until the hydraulic pressure is secured by the oil pump after the foot is removed from the brake pedal and the engine is restarted. When the accelerator pedal is stepped on immediately after the release, the engine speed increases before the clutch is engaged, and there is a problem that the shock when the clutch is engaged increases.

  That is, as shown in the graph of FIG. 4, the shock when the clutch is connected has a large correlation with the engine speed at the time of connection, and it has been found that the higher the engine speed at this time, the greater the shock. .

  The present invention has been made in view of the above-described circumstances, and an object thereof is to reduce a shock at the time of clutch engagement at the time of restart of an engine provided with an idle stop system.

The present invention relates to a method for restarting an engine with a torque converter having an idle stop system that automatically stops the engine when the vehicle is stopped and restarts the engine when the vehicle starts, and the clutch is connected after the engine is restarted. Until the engine is completed, fuel injection control to the engine is performed so that the engine speed is maintained at a predetermined limit value that does not exceed the idle speed, and the accelerator pedal is depressed before the clutch connection is completed. When the engine speed limit is released due to the clutch being engaged, gradually increase the speed by applying gradual change control to the speed increase according to the accelerator pedal depression angle. It is a feature.

  Thus, since the engine speed is limited to the idling speed or less after the engine is restarted until the clutch connection is completed, the accelerator pedal is set before the clutch connection is completed. Even if the engine is stepped on, the engine speed does not increase beyond the idle speed, and the shock at the time of clutch engagement is greatly reduced.

  In the present invention, the engine speed limit value is preferably determined within a range where the idle speed is the upper limit and the engine speed is 100 rpm lower than the idle speed. It is possible to reliably suppress a shock when the clutch is connected and maintain a stable idling state without causing an engine stall or the like.

  According to the engine restart method provided with the idle stop system of the present invention described above, the engine speed can be limited to the idle speed or less after the engine is restarted until the clutch connection is completed. Even if the accelerator pedal is depressed before the clutch connection is completed, the shock at the time of clutch connection can be greatly reduced, and the existing equipment can be used as it is simply by devising the control method. Therefore, it is possible to achieve an excellent effect that an increase in cost can be suppressed.

It is the schematic which shows an example of the form which implements this invention. It is the figure which put together the control procedure at the time of a stop of an idle stop system. It is the figure which put together the control procedure at the time of start of an idle stop system. It is a graph which shows the relationship between the shock at the time of a clutch connection, and an engine speed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an example of an engine equipped with an idle stop system. In the figure, 1 is an engine, 2 is a torque converter, 3 is an oil pump built in the torque converter 2, and 4 is generated by the oil pump 3. A hydraulic clutch that is connected and operated by hydraulic pressure, 5 is a brake, 6 is a control device that constitutes an engine control computer (ECU), a rotation sensor 7 that detects the number of revolutions of the engine 1, The vehicle speed sensor 8 that detects the vehicle speed, the brake pedal sensor 10 that detects the depression of the brake pedal 9 in the driver's seat, the accelerator sensor 12 that detects the depression angle of the accelerator pedal 11 in the driver's seat, and the completion of connection of the clutch 4 are detected. Signals 7a, 8a, 10a, 12a, 13a from the clutch sensor 13 to be input are input to the control device 6, respectively. It has become to so that.

  On the other hand, a signal 1a is output from the control device 6 to the engine 1 so that the engine 1 is started and stopped and the fuel injection amount is controlled. 5a is output to control the operation / non-operation.

  The specific control procedure of the idle stop system by the control device 6 is described in detail below. First, when the vehicle is stopped, the brake pedal sensor is controlled by the control device 6 as summarized in FIG. When it is confirmed that the brake 5 has been depressed by the signal 10a from the vehicle 10 and the vehicle speed has been confirmed to be 0 by the signal 8a from the vehicle speed sensor 8, the brake 5 is activated by the signal 5a from the control device 6. On the other hand, the engine 1 is automatically stopped by a signal 1a from the control device 6.

  And when starting again from such a temporary stop state, as outlined in FIG. 3, the foot is removed from the brake pedal 9 by the control device 6 by the signal 10a from the brake pedal sensor 10. If it is confirmed, the engine 1 is restarted by the signal 1a from the control device 6 and the torque converter 2 is also started. The oil pump 3 built in the torque converter 2 generates hydraulic pressure and the clutch 4 is connected. It has come to be.

  At this time, in this embodiment, a predetermined limit value is set so that the rotational speed of the engine 1 does not exceed the idle rotational speed until the connection of the clutch 4 is completed after the engine 1 is restarted. 1 is limited, and more specifically, a limit value is set within a range in which the idling engine speed is the upper limit and the engine speed is 100 rpm lower than the idling engine speed. Fuel injection control to the engine 1 is performed by a signal 1a from the control device 6 so that the rotational speed of the engine 1 is maintained.

  Such a rotational speed limit of the engine 1 is released when the connection of the clutch 4 is confirmed by the control device 6 by a signal 13a from the clutch sensor 13, and at this time, if the accelerator pedal 11 is not yet depressed, The rotational speed of the engine 1 returns to the normal idle rotational speed.

  The brake 5 is released by the signal 5a from the control device 6 when the depression of the accelerator pedal 11 is confirmed by the control device 6 by the signal 12a from the accelerator sensor 12.

  Thus, if the control at the time of restart in the idle stop system is performed using such a method, the number of revolutions of the engine 1 until the connection of the clutch 4 is completed after the engine 1 is restarted. Therefore, even if the accelerator pedal 11 is depressed before the connection of the clutch 4 is completed, the engine speed does not increase beyond the idle engine speed. The shock when the clutch 4 is connected is greatly reduced.

  In particular, in the present embodiment, the limit value of the engine speed is set within a range where the idle speed is the upper limit and the engine speed is 100 rpm lower than the idle speed. It is possible to reliably suppress a shock at the time of connection and maintain a stable idling state that does not cause an engine stall or the like.

  That is, the engine speed limit value of the engine 1 can be expected to reduce the shock as the engine speed is less than the idling speed. However, if the engine speed is excessively lowered, the idling becomes unstable and the engine stalls easily. It is preferable to set the value within a range in which the idling engine speed is set as the upper limit and the engine speed lower by 100 rpm than the idling engine speed is set as the lower limit.

  In addition, when the accelerator pedal 11 is depressed before the connection of the clutch 4 is completed, when the rotation speed limit of the engine 1 is released by the connection of the clutch 4, the rotation according to the depression angle of the accelerator pedal 11 is performed. The increase to the number starts, but it is preferable that the number of rotations at this time is moderately controlled so that the number of rotations gradually increases.

  Therefore, according to the above embodiment, since the engine 1 can be limited to the idling speed or less until the connection of the clutch 4 is completed after the engine 1 is restarted, the connection of the clutch 4 is completed. Even if the accelerator pedal 11 is depressed before starting, the shock when the clutch 4 is connected can be greatly reduced, and the existing equipment can be used as it is simply by devising the control method. Therefore, it is possible to suppress an increase in cost.

  It should be noted that the restart method of the engine equipped with the idle stop system of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. is there.

1 Engine 4 Clutch 6 Control Device 7 Rotation Sensor 13 Clutch Sensor

Claims (2)

A method for restarting an engine with a torque converter having an idle stop system that automatically stops the engine when the vehicle is stopped and restarts the engine when the vehicle starts, from when the engine is restarted until the clutch is completely connected Performs fuel injection control to the engine so that the engine speed is maintained at a predetermined limit value that does not exceed the idle speed, and the accelerator pedal is depressed before the clutch connection is completed. When the engine speed limit is released by connecting the clutch, the engine speed is gradually increased by gradually controlling the engine speed to increase according to the accelerator pedal depression angle. How to restart an engine with a stop system.   2. The idle stop system according to claim 1, wherein the engine speed limit value is determined within a range in which the upper limit is the idle speed and the lower limit is 100 rpm less than the idle speed. How to restart the engine.

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