JP2014159753A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine, capable of making a driver perceive decrease of a fuel amount before the fuel amount decreases to automatically stop an internal combustion engine.SOLUTION: When a fuel amount in a fuel tank is less than a first predetermined value, an internal combustion engine is stopped. When the fuel amount is more than a second predetermined value larger than the first predetermined value, torque characteristics of the internal combustion engine is set to first characteristics. When the fuel amount is equal to or more than the first predetermined value and is equal to or less than the second predetermined value, the torque characteristics of the internal combustion engine is set to second characteristics different from the first characteristics.

Description

  The present invention relates to a control device for an internal combustion engine mounted on a vehicle.

  When the amount of fuel stored in the fuel tank of the internal combustion engine decreases, air is mixed into the fuel pumped up by the fuel pump. Therefore, it becomes difficult to inject a desired amount of fuel from the fuel injection valve, and misfire is likely to occur. When a misfire occurs in this way, oxygen contained in the exhaust gas and fuel may react with each other in the catalytic converter, and the catalytic converter may be overheated. In order to suppress this, in the control apparatus for an internal combustion engine described in Patent Document 1, the internal combustion engine is automatically stopped when the amount of fuel stored in the fuel tank falls below a predetermined amount.

JP-A-5-263695

  By the way, if the internal combustion engine is automatically stopped in this way, overheating of the catalytic converter can be prevented, but the driver cannot perceive a decrease in the fuel amount until the internal combustion engine is automatically stopped.

  The present invention has been made in view of such circumstances, and an object of the present invention is to allow a driver to perceive a decrease in the amount of fuel before the amount of fuel decreases and the internal combustion engine automatically stops. It is to provide a control device.

  The control device for an internal combustion engine that solves the above problem stops the internal combustion engine when the amount of fuel in the fuel tank is less than a first predetermined value, and the fuel amount exceeds a second predetermined value that is greater than the first predetermined value. Is greater than the first predetermined value and less than the second predetermined value, the torque characteristic of the internal combustion engine is referred to as the first characteristic. Have different second characteristics.

  According to the above configuration, when the fuel amount is equal to or greater than the first predetermined value, the torque characteristics of the internal combustion engine differ depending on whether the fuel amount is equal to or less than the second predetermined value. For this reason, the driver can perceive the remaining amount of fuel before the internal combustion engine automatically stops based on the change in the torque characteristic.

  In the control device for an internal combustion engine, when the torque characteristic of the internal combustion engine is the second characteristic, it is desirable to make the engine torque corresponding to the accelerator opening smaller than when the torque characteristic is the first characteristic.

  According to the above configuration, when the fuel amount becomes equal to or less than the second predetermined value, the engine torque corresponding to the accelerator opening becomes small, so that the driver can perceive a decrease in the fuel amount.

  Further, in the control device for an internal combustion engine, when the torque characteristic of the internal combustion engine is the second characteristic, it corresponds to the accelerator opening after the accelerator opening is increased after the accelerator opening is increased as compared with the first characteristic. It is desirable to lengthen the time until the engine torque is generated.

  In the above configuration, when the fuel amount is equal to or less than the second predetermined value, the time from when the accelerator opening increases until the engine torque corresponding to the increased accelerator opening is generated becomes longer. Thus, the driver can perceive a decrease in the fuel amount. Here, the time may be lengthened as the amount of fuel decreases. In this way, the generation of engine torque corresponding to the accelerator opening becomes slower as the fuel amount decreases and approaches the first predetermined value, so the driver can more easily perceive the decrease in fuel amount. On the other hand, when the fuel amount is slightly smaller than the second predetermined value, the engine torque corresponding to the accelerator opening is generated at an earlier timing, so that it is possible to suppress a decrease in vehicle running performance.

  Further, when the fuel amount exceeds the second predetermined value after changing the torque characteristic of the internal combustion engine to the second characteristic in the control device for the internal combustion engine, the torque characteristic is changed from the second characteristic to the first characteristic. It is desirable to return gradually. In this way, the driver's uncomfortable feeling associated with returning the torque characteristic of the internal combustion engine to the first characteristic can be alleviated.

  Further, when the torque characteristic of the internal combustion engine is set to the second characteristic in the control device for the internal combustion engine, it is preferable to vibrate the vehicle by controlling the ignition timing and the throttle opening to vary the engine torque.

  In the above configuration, the vehicle is vibrated when the fuel amount becomes equal to or less than the second predetermined value, so that the driver can perceive a decrease in the fuel amount.

1 is a schematic diagram showing a schematic configuration of a control device for an internal combustion engine. The flowchart which shows the execution procedure at the time of making an internal combustion engine stop automatically. The graph which shows an example of the correspondence of accelerator opening and engine torque. (A), (b) is a time chart which shows an example of the generation | occurrence | production aspect of an engine torque when the accelerator opening increases. (A)-(c) is a time chart which shows an example of the control aspect when controlling ignition timing and vibrating a vehicle. The graph which shows another example of the correspondence of an accelerator opening and engine torque. (A), (b) is a time chart which shows another example of the generation | occurrence | production aspect of an engine torque when the accelerator opening increases.

(First embodiment)
Hereinafter, a first embodiment of a control device for an internal combustion engine will be described with reference to FIGS.

  As shown in FIG. 1, an intake passage 2 and an exhaust passage 3 are connected to a combustion chamber 1 of an internal combustion engine mounted on a vehicle. A throttle valve 4 that adjusts the amount of intake air introduced into the combustion chamber 1 is provided in the intake passage 2. A fuel injection valve 5 is provided downstream of the throttle valve 4 in the intake flow direction in the intake passage 2. The fuel injection valve 5 is connected to a fuel tank 8 by a fuel supply passage 7 provided with a fuel pump 6 in the middle thereof.

  The fuel stored in the fuel tank 8 is pumped up by the fuel pump 6 and supplied to the fuel injection valve 5 through the fuel supply passage 7. The fuel tank 8 is provided with a fuel gauge 9 for detecting the amount of fuel in the fuel tank 8.

  Further, the internal combustion engine is provided with a spark plug 10 for combusting an air-fuel mixture of fuel injected from the fuel injection valve 5 and intake air in the combustion chamber 1. Further, the exhaust passage 3 is provided with a catalytic converter 11 for purifying the exhaust discharged from the combustion chamber 1.

  Further, detection signals from various sensors provided for detecting the operation state of the internal combustion engine are input to the control device 12 for the internal combustion engine. Examples of such sensors include an accelerator sensor 13 and a fuel gauge 9 for detecting the accelerator opening. The control device 12 of the internal combustion engine executes various controls such as throttle opening control, fuel injection amount control, and ignition timing control based on such signals. As one of such controls, the control device 12 of the internal combustion engine reduces the engine torque corresponding to the accelerator opening when the fuel amount in the fuel tank 8 decreases, and when the fuel amount further decreases, the internal combustion engine is turned off. Executes automatic stop control.

  Hereinafter, the execution procedure of this control will be described with reference to the flowchart of FIG. The series of processing shown in this flowchart is executed by the control device 12 of the internal combustion engine as interruption processing at predetermined intervals.

  As shown in FIG. 2, in this process, first, it is determined whether or not the amount of fuel in the fuel tank 8 is equal to or smaller than a second predetermined value (step S1). If it is determined in step S1 that the amount of fuel is greater than the second predetermined value (step S1: NO), the process proceeds to step S6 to determine whether the flag F is 1 or not. To do. If it is determined in this process that the flag F is not 1 (step S6: NO), the process proceeds to step S9, the torque characteristic of the internal combustion engine is set to the first characteristic, and this process is terminated. .

  On the other hand, if it is determined in step S1 that the fuel amount is less than or equal to the second predetermined value (step S1: YES), it is next determined whether or not the fuel amount is less than the first predetermined value. (Step S2). Here, the maximum value of the fuel amount that may cause the catalytic converter 11 to overheat due to misfire is set as the first predetermined value, and a value larger than the first predetermined value is set as the second predetermined value. (First predetermined value <second predetermined value). When it is determined in step S2 that the amount of fuel is less than the first predetermined value (step S2: YES), that is, the amount of fuel in the fuel tank 8 is very small, and the fuel injection amount is insufficient. If it is determined that misfire has occurred and the catalytic converter 11 may be overheated, the process proceeds to step S3 to automatically stop the internal combustion engine, and then the present process is terminated.

  Further, when it is determined in step S2 that the fuel amount is equal to or larger than the first predetermined value (step S2: NO), that is, the fuel amount is equal to or larger than the first predetermined value and equal to or smaller than the second predetermined value. If it is determined that there is, the process proceeds to step S4. In the process of step S4, the torque characteristic of the internal combustion engine is set to the second characteristic. Then, after proceeding to the process of step S5 and setting the flag F to 1, this process is terminated.

  Next, a correspondence relationship between the accelerator opening and the engine torque when the torque characteristic of the internal combustion engine is the second characteristic will be described with reference to FIG. The solid line and the alternate long and short dash line in FIG. 3 indicate the correspondence between the accelerator opening and the engine torque when the first characteristic and the second characteristic, respectively.

  As shown in FIG. 3, when the torque characteristic of the internal combustion engine is the second characteristic, the engine torque corresponding to the accelerator opening when the engine operating state is the same is compared with the first characteristic. It is set to be smaller. More specifically, in the second characteristic, the increase degree of the engine torque with respect to the increase in the accelerator opening is made smaller than that in the first characteristic. Therefore, when the torque characteristic of the internal combustion engine is set to the second characteristic by the process of step S4 in FIG. 2, the running performance of the vehicle is reduced as compared with the case where the torque characteristic of the internal combustion engine is the first characteristic. .

  On the other hand, when the torque characteristic of the internal combustion engine is set to the second characteristic in this way, the flag F is set to 1, so that a positive determination is made in the process of step S6 (step S6: YES). That is, when it is determined that the flag F is 1 in the same process, it can be determined that the fuel amount in the fuel tank 8 exceeds the second predetermined value after the torque characteristic is set to the second characteristic. . In such a case, the process proceeds to step S7, and the torque characteristic of the internal combustion engine is gradually returned from the second characteristic to the first characteristic. As a method of gradually returning from the second characteristic to the first characteristic, for example, every time a predetermined time elapses, the engine torque corresponding to the accelerator opening when the torque characteristic of the internal combustion engine is the second characteristic is used. A method such as increasing by a predetermined amount may be used as appropriate. Thereafter, when the torque characteristic is returned to the first characteristic, the flag F is set to 0 (step S8), and this process is terminated.

Next, the operation of the control device 12 for the internal combustion engine of the present embodiment will be described.
In the internal combustion engine control device 12 described above, the internal combustion engine is automatically stopped when the amount of fuel in the fuel tank 8 becomes less than the first predetermined value. Further, when the fuel amount is larger than the second predetermined value, the torque characteristic of the internal combustion engine is set to the first characteristic. On the other hand, when the fuel amount is not less than the first predetermined value and not more than the second predetermined value, the torque characteristic of the internal combustion engine is set to the second characteristic. That is, when the fuel amount is equal to or greater than the first predetermined value, the torque characteristics of the internal combustion engine vary depending on whether the fuel amount is equal to or less than the second predetermined value. When the torque characteristic of the internal combustion engine is changed to the second characteristic, the engine torque corresponding to the accelerator opening is made smaller than when the torque characteristic is the first characteristic. Further, when the amount of fuel exceeds the second predetermined value after changing the torque characteristic of the internal combustion engine to the second characteristic, the torque characteristic of the internal combustion engine is gradually returned to the first characteristic.

According to the first embodiment described above, the following effects can be obtained.
(1) When the fuel amount is not less than the first predetermined value and not more than the second predetermined value, the torque characteristic of the internal combustion engine is changed to a second characteristic different from the first characteristic, and corresponds to the accelerator opening. The engine torque was made smaller than when it was the first characteristic. For this reason, the driver can perceive the remaining amount of fuel before the internal combustion engine automatically stops based on the change in the torque characteristic.

(2) Since the torque characteristic of the internal combustion engine is gradually returned from the second characteristic to the first characteristic, the driver's uncomfortable feeling associated with returning the torque characteristic of the internal combustion engine to the first characteristic can be alleviated. it can.
(Second Embodiment)
Next, a second embodiment of the control device 12 for an internal combustion engine will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment, a common code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  As shown in FIG. 4 (a), when the accelerator opening increases when the torque characteristic of the internal combustion engine is the first characteristic, the engine torque gradually increases as shown by the solid line in FIG. 4 (b). The engine torque corresponding to the accelerator opening after the increase is generated.

  On the other hand, as shown by a chain line in FIG. 4B, when the accelerator opening increases when the torque characteristic of the internal combustion engine is the second characteristic, the rate of increase of the engine torque accompanying the increase in the accelerator opening. Is smaller than when the value is the first characteristic. Therefore, when the torque characteristic of the internal combustion engine is the second characteristic, even if the driver increases the accelerator opening by performing the accelerator operation, the engine torque corresponding to the increased accelerator opening is generated. The time to do this is longer than when the first characteristic is reached. Further, as the fuel amount in the fuel tank 8 is smaller, the rate of increase of the engine torque is reduced, and as the fuel amount is smaller, the time until the engine torque is generated accompanying the increase in the accelerator opening is lengthened. Then, when the amount of fuel exceeds the second predetermined value after changing the torque characteristic of the internal combustion engine to the second characteristic, the torque characteristic of the internal combustion engine is gradually returned to the first characteristic.

According to the second embodiment described above, in addition to the effect (2), the following effect can be obtained.
(3) When the fuel amount is not less than the first predetermined value and not more than the second predetermined value, the torque characteristic of the internal combustion engine is changed to a second characteristic different from the first characteristic, and the accelerator opening is increased. Then, the time until the engine torque corresponding to the accelerator opening after the increase is generated is lengthened. For this reason, the driver can perceive the remaining amount of fuel before the internal combustion engine automatically stops based on the change in the torque characteristic.

(4) When the fuel amount is not less than the first predetermined value and not more than the second predetermined value, the time until the engine torque corresponding to the accelerator opening is generated becomes longer as the fuel amount is smaller. As the fuel amount decreases and approaches the first predetermined value, the generation of the engine torque corresponding to the accelerator opening becomes slower, and the driver can more easily perceive the decrease in the fuel amount. On the other hand, when the fuel amount is slightly smaller than the second predetermined value, the engine torque corresponding to the accelerator opening is generated at an earlier timing, so that it is possible to suppress a decrease in vehicle running performance.
(Third embodiment)
Next, a third embodiment of the control device 12 for an internal combustion engine will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment, a common code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  As shown in FIG. 5, when the amount of fuel in the fuel tank 8 becomes equal to or smaller than the second predetermined value and the torque characteristic of the internal combustion engine is set to the second characteristic, the control device 12 of the internal combustion engine sets the ignition timing to the first timing. For example, it is periodically changed to the retard side from the ignition timing set when the characteristic is 1. Thus, when the ignition timing changes periodically, the engine torque changes periodically. Therefore, as shown in FIG.5 (c), the acceleration of a vehicle changes and a vehicle is vibrated.

  In the present embodiment, when it is determined that the flag F is 1 in the process of step 6 of FIG. 2 (step S6: YES), that is, after the torque characteristic is set to the second characteristic, the fuel in the fuel tank 8 When the amount exceeds the second predetermined value, a process of immediately returning the torque characteristic of the internal combustion engine from the second characteristic to the first characteristic is executed instead of the process of step S7. Thereafter, the flag F is set to 0 as in the process of step S8, and this process ends.

Next, the operation of the control device 12 for the internal combustion engine of the present embodiment will be described.
In the control device 12 for the internal combustion engine described above, when the fuel amount in the fuel tank 8 is not less than the first predetermined value and not more than the second predetermined value, the ignition timing is controlled to periodically vary the engine torque. This causes the vehicle to vibrate.

Further, when the amount of fuel in the fuel tank 8 exceeds the second predetermined value after setting the torque characteristic of the internal combustion engine to the second characteristic, the torque characteristic of the internal combustion engine is immediately returned to the first characteristic.
According to the third embodiment described above, the following effects can be obtained.

(5) When the fuel amount is not less than the first predetermined value and not more than the second predetermined value, the torque characteristic of the internal combustion engine is changed to a second characteristic different from the first characteristic, and the ignition timing is controlled. Thus, the vehicle is vibrated by periodically changing the engine torque. For this reason, the driver can perceive the remaining amount of fuel before the internal combustion engine automatically stops based on the change in the torque characteristic.
(Other embodiments)
In addition, each said embodiment can also be changed and implemented as follows. In addition, it can also implement combining said each embodiment and the following modified examples suitably.

  In the first embodiment, when the torque characteristic of the internal combustion engine is the second characteristic, the degree of increase in the engine torque with respect to the increase in the accelerator opening may be reduced as the fuel amount is smaller.

  In the first embodiment, when the torque characteristic of the internal combustion engine is the second characteristic, the degree of increase in the engine torque with respect to the increase in the accelerator opening is made smaller than that in the first characteristic, The engine torque corresponding to the accelerator opening was reduced. However, the aspect in which the engine torque corresponding to the accelerator opening is made smaller than that in the first characteristic is not limited to this, and may be changed to, for example, the aspect shown in FIG.

  As shown in FIG. 6, when the torque characteristic of the internal combustion engine is the second characteristic, a dead zone region in which the engine torque is not increased until the accelerator opening reaches a predetermined opening is set. Further, the degree to which the engine torque increases with respect to the increase in the accelerator opening after the accelerator opening reaches the predetermined opening is set to the same degree as that in the first characteristic. Even in such a configuration, when the torque characteristic of the internal combustion engine is the second characteristic, the engine torque corresponding to the accelerator opening is smaller than that when the torque characteristic is the first characteristic. The same effect as (2) can be obtained.

  In such a configuration, if the predetermined opening degree is increased and the dead zone region is enlarged as the fuel amount is smaller, the accelerator opening degree can be accommodated as the fuel amount decreases and approaches the first predetermined value. Since the engine torque to be reduced becomes smaller, it becomes easier for the driver to perceive the decrease in the fuel amount. On the other hand, when the fuel amount is slightly smaller than the second predetermined value, a decrease in engine torque corresponding to the accelerator opening is suppressed, so that a decrease in vehicle running performance can be suppressed.

  In the second embodiment, when the torque characteristic of the internal combustion engine is the second characteristic, the time from when the accelerator opening increases until the engine torque corresponding to the increased accelerator opening is generated is determined as fuel. The longer the amount, the longer. However, such a configuration may be omitted. Even in such a case, the same effects as in the above (2) and (3) can be obtained.

  -In 2nd Embodiment, when the torque characteristic of an internal combustion engine is a 2nd characteristic, it respond | corresponds to an accelerator opening by making the increase speed of an engine torque small compared with the time of being a 1st characteristic. Increased the time until the engine torque is generated. However, the mode of extending the same time is not limited to this, and may be changed to, for example, the mode shown in FIG.

  As shown in FIG. 7, when the torque characteristic of the internal combustion engine is the first characteristic, when the accelerator opening increases, the engine torque gradually increases and the engine torque corresponding to the increased accelerator opening is generated. To do.

  On the other hand, when the torque characteristic of the internal combustion engine is the second characteristic, if the accelerator opening increases, the engine torque increases after a predetermined response delay time elapses. For this reason, the time until the engine torque corresponding to the driver's accelerator operation is generated is longer than that in the first characteristic. Therefore, even with such a configuration, the same effects as in the above (2) and (3) can be obtained.

  In such a configuration, if the response delay time is increased as the fuel amount in the fuel tank 8 is smaller, the same effect as in the above (4) can be obtained in addition to the same effect as in the above (2) and (3). Can be obtained.

  In the first and second embodiments, when the amount of fuel in the fuel tank 8 exceeds the second predetermined value after the torque characteristic of the internal combustion engine is set to the second characteristic, the torque characteristic of the internal combustion engine is changed to the first characteristic. However, such a configuration may be omitted. For example, when the torque characteristic of the internal combustion engine is returned from the second characteristic to the first characteristic, the torque characteristic may be changed immediately. Even with this configuration, it is possible to obtain the same effect as the above (1) or (3).

  In the third embodiment, when the torque characteristic of the internal combustion engine is the second characteristic, the vehicle is vibrated by periodically changing the ignition timing, but the throttle valve is periodically changed. The vehicle may be vibrated. Even with such a configuration, the same effect as the above (5) can be obtained.

  -Control of each embodiment except a 3rd embodiment can also be applied to a diesel engine.

  DESCRIPTION OF SYMBOLS 1 ... Combustion chamber, 2 ... Intake passage, 3 ... Exhaust passage, 4 ... Throttle valve, 5 ... Fuel injection valve, 6 ... Fuel pump, 7 ... Fuel supply passage, 8 ... Fuel tank, 9 ... Fuel gauge, 10 ... Ignition Plug, 11 ... catalytic converter, 12 ... control device, 13 ... accelerator sensor.

Claims (7)

When the amount of fuel in the fuel tank is less than the first predetermined value, the internal combustion engine is stopped, and when the amount of fuel is greater than the second predetermined value greater than the first predetermined value, the torque characteristic of the internal combustion engine is set to the first characteristic. The internal combustion engine torque characteristic is a second characteristic different from the first characteristic when the fuel amount is not less than the first predetermined value and not greater than the second predetermined value. apparatus. The control device for an internal combustion engine according to claim 1, wherein when the torque characteristic of the internal combustion engine is the second characteristic, the engine torque corresponding to the accelerator opening is made smaller than when the torque characteristic is the first characteristic. When the torque characteristic of the internal combustion engine is the second characteristic until the engine torque corresponding to the increased accelerator opening is generated after the accelerator opening is increased as compared with the first characteristic. The control device for an internal combustion engine according to claim 1 or 2. The control device for an internal combustion engine according to claim 3, wherein the time is increased as the amount of fuel is smaller. The torque characteristic is gradually returned from the second characteristic to the first characteristic when the amount of fuel exceeds the second predetermined value after changing the torque characteristic of the internal combustion engine to the second characteristic. The control apparatus of the internal combustion engine as described in any one of 1-4. The control apparatus for an internal combustion engine according to claim 1, wherein when the torque characteristic of the internal combustion engine is the second characteristic, the vehicle is vibrated by controlling the ignition timing to vary the engine torque. The control device for an internal combustion engine according to claim 1, wherein when the torque characteristic of the internal combustion engine is the second characteristic, the vehicle is vibrated by controlling the throttle opening to vary the engine torque.