JP7537270B2 - vehicle - Google Patents

Description

The present invention relates to a vehicle.

Conventionally, this type of vehicle has an idling stop control that automatically stops the engine when a specified stop condition is met and automatically starts the engine when a specified restart condition is met. In this case, if pre-ignition occurs before the engine is automatically stopped, the engine is controlled so that the air-fuel ratio becomes rich after the engine is automatically started (see, for example, Patent Document 1).

JP 2013-234578 A

In the above-mentioned vehicles, as the mileage increases and engine oil deterioration progresses, making the engine more susceptible to pre-ignition, the engine becomes more likely to be controlled to have a rich air-fuel ratio, which can result in poor fuel economy.

The main purpose of the vehicle of the present invention is to suppress deterioration of fuel efficiency.

The vehicle of the present invention employs the following means to achieve the above-mentioned main objective.

The vehicle of the present invention comprises:
A vehicle including an engine having a fuel injection valve and a control device that controls the engine,
the control device performs an increase correction on the fuel injection amount from the fuel injection valve in a current trip when the number of occurrences of pre-ignition of the engine in a previous trip reaches or exceeds a threshold value,
The threshold value is set to be larger when the travel distance is long than when the travel distance is short.
The gist of the present invention is as follows.

In the vehicle of the present invention, when the number of occurrences of engine pre-ignition in the previous trip reaches or exceeds a threshold value, an increase correction is made to the fuel injection amount from the fuel injection valve in the current trip. This makes it possible to suppress the occurrence of engine pre-ignition in the current trip. The threshold value is set to be larger when the mileage is long than when it is short. This makes it possible to suppress the tendency to increase the fuel injection amount due to pre-ignition in the current trip when the mileage is long and the engine oil deteriorates, making it easier for engine pre-ignition to occur, and suppress deterioration of fuel economy. Here, the "mileage" may be the mileage since the previous engine oil change.

In the vehicle of the present invention, the control device may execute the increase correction when the mileage at the start of the current trip is equal to or greater than a predetermined distance, regardless of the number of times the engine pre-ignition occurred in the previous trip.

In the vehicle of the present invention, the control device may not execute the increase correction in the current trip if the increase correction was executed in the previous trip and the engine maintenance, including engine oil change, was performed between the end of the previous trip and the start of the current trip.

1 is a diagram showing an outline of the configuration of an automobile 10 according to an embodiment of the present invention; 4 is a flowchart showing an example of a fuel increase flag setting routine executed by an electronic control unit 70. FIG. 11 is an explanatory diagram showing an example of a threshold setting map; 11 is an explanatory diagram showing an example of the state of a detection counter Cpi for the first to fourth trips, an oil change flag Foc, and a fuel increase flag Ff. FIG. 4 is a flowchart showing an example of a fuel increase flag setting routine executed by an electronic control unit 70.

Next, we will explain how to implement the present invention using examples.

Figure 1 is a schematic diagram showing the configuration of an automobile 10 as one embodiment of the present invention. As shown in the figure, the automobile 10 of the embodiment includes an engine 12, a transmission 60 connected to the crankshaft 14 of the engine 12 and connected to drive wheels 64a, 64b via a differential gear 62, a starter (not shown) for starting the engine 12, and an electronic control unit 70 for controlling the entire vehicle.

The engine 12 is configured as an internal combustion engine that uses fuel such as gasoline or diesel to output power through four strokes: intake, compression, expansion, and exhaust. In this engine 12, air cleaned by an air cleaner 22 is drawn into an intake pipe 23, passed through a throttle valve 24, and fuel is injected from a fuel injection valve 26 downstream of the throttle valve 24 of the intake pipe 23 to mix the air and fuel. This mixture is then drawn into a combustion chamber 29 via an intake valve 28, where it is explosively combusted by an electric spark from an ignition plug 30, and the reciprocating motion of a piston 32 pushed down by the energy of the explosive combustion is converted into the rotational motion of a crankshaft 14. The exhaust gas discharged from the combustion chamber 29 to an exhaust pipe 34 via an exhaust valve 33 is discharged to the outside air via a purification device 35. The purification device 35 has a catalyst (three-way catalyst) 35a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

The electronic control unit 70 is configured as a microprocessor with a CPU at its core, and in addition to the CPU, it is equipped with a ROM for storing processing programs, a RAM for temporarily storing data, a flash memory for storing and holding data, and input/output ports. Signals from various sensors are input to the electronic control unit 70 via the input ports.

Examples of signals input to the electronic control unit 70 include the crank angle θcr from the crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, and the cooling water temperature Tw from the water temperature sensor 15 that detects the temperature of the cooling water of the engine 12. Examples of signals input to the electronic control unit 70 include the throttle opening TH from the throttle position sensor 24a that detects the opening (position) of the throttle valve 24, and the cam angles θci and θco from the cam position sensor 16 that detects the rotational positions of the intake camshaft that opens and closes the intake valve 28 and the exhaust camshaft that opens and closes the exhaust valve 33. Examples of the intake air amount Qa from the air flow meter 23a attached upstream of the throttle valve 24 of the intake pipe 23, the intake air temperature Ta from the temperature sensor 23b attached upstream of the throttle valve 24 of the intake pipe 23, the front air-fuel ratio AF1 from the front air-fuel ratio sensor 37 attached upstream of the purifier 35 of the exhaust pipe 34, and the rear air-fuel ratio AF2 from the rear air-fuel ratio sensor 38 attached downstream of the purifier 35 of the exhaust pipe 34 can also be mentioned. Examples of the ignition signal IG from the ignition switch 80 and the shift position SP from the shift position sensor 82 that detects the operating position of the shift lever 81 can also be mentioned. Examples of the accelerator opening Acc from the accelerator pedal position sensor 84 that detects the amount of depression of the accelerator pedal 83, the brake pedal position BP from the brake pedal position sensor 86 that detects the amount of depression of the brake pedal 85, and the vehicle speed V from the vehicle speed sensor 88 can also be mentioned.

Various control signals are output from the electronic control unit 70 via the output port. Examples of signals output from the electronic control unit 70 include a control signal to the throttle valve 24, a control signal to the fuel injection valve 26, and a control signal to the spark plug 30. Other examples include a control signal to the transmission 60 and a control signal to a starter (not shown).

The electronic control unit 70 calculates the rotation speed Ne of the engine 12 based on the crank angle θcr from the crank position sensor 14a. The electronic control unit 70 also calculates the load factor KL (the ratio of the volume of air actually taken in during one cycle to the stroke volume per cycle of the engine 12) based on the intake air volume Qa from the air flow meter 23a and the rotation speed Ne of the engine 12.

In the automobile 10 of the embodiment thus configured, the electronic control unit 70 performs operation control of the engine 12 based on the required load rate KL* of the engine 12, which is based on the accelerator opening Acc and the vehicle speed V, specifically, intake air volume control that controls the opening of the throttle valve 24, fuel injection control that controls the amount of fuel injected from the fuel injection valve 26, and ignition control that controls the ignition timing of the spark plug 30.

In the intake air volume control, the electronic control unit 70 sets a target intake air volume Qa* based on the required load rate KL*, and controls the throttle valve 24 by setting a target throttle opening TH* of the throttle valve 24 so that the intake air volume Qa becomes the target intake air volume Qa*. In the ignition control, the electronic control unit 70 sets a target ignition timing Ti* of the spark plug 30 based on the engine 12 speed Ne and the load rate KL, and controls the spark plug 30.

In fuel injection control, the electronic control unit 70 first sets a provisional injection amount Qftmp as a provisional value of the target injection amount Qf* of the fuel injection valve 26 so that the front air-fuel ratio AF1 becomes the target air-fuel ratio AF* (e.g., theoretical air-fuel ratio) based on the rotation speed Ne and the load factor KL of the engine 12. Next, the value of the fuel increase flag Ff described below is checked. When the fuel increase flag Ff is a value of 0, the provisional injection amount Qftmp is set to the target injection amount Qf* to control the fuel injection valve 26. When the fuel increase flag Ff is a value of 1, the provisional injection amount Qftmp is multiplied by a coefficient kf greater than a value of 1 to set the target injection amount Qf* to control the fuel injection valve 26. Hereinafter, setting the target injection amount Qf* to a value greater than the provisional injection amount Qftmp is referred to as a "predetermined increase correction."

Next, the operation of the automobile 10 of the embodiment thus configured, particularly the operation when setting the fuel increase flag Ff, will be described. FIG. 2 is a flowchart showing an example of a fuel increase flag setting routine executed by the electronic control unit 70. This routine is executed at the start of each trip.

When the fuel increase flag setting routine in FIG. 2 is executed, the electronic control unit 70 first checks the current value of the fuel increase flag Ff (step S100). Since the start of the current trip is considered, the current value of the fuel increase flag Ff indicates whether or not an increase correction was made to the fuel injection amount in the previous trip.

When the current value of the fuel increase flag Ff is 0 in step S100, it is determined that the fuel injection amount was not increased in the previous trip, and data such as the mileage Loc after the engine oil change and the number of times pre-ignition (PI: Pre-ignition) was detected in the previous trip Npi are input (step S110). Here, the mileage Loc after the engine oil change is, for example, a value calculated as the integrated value of the vehicle speed V from the time of the engine oil change to the end of the previous trip. The number of times pre-ignition was detected in the previous trip Npi is, for example, the value at the start of the current trip of a detection counter Cpi that is reset to 0 at the end of execution of this routine and is counted up each time pre-ignition is detected. The presence or absence of pre-ignition is determined, for example, using a detection value by an ion current detection device (not shown) that detects the ion current generated in the spark plug 30 due to combustion in the combustion chamber 29 of the engine 12.

After inputting the data in this way, the threshold value Npiref is set based on the mileage Loc after the engine oil change (step S120), and the number of pre-ignition detections Npi in the previous trip is compared with the threshold value Npiref (step S130). Then, when the number of pre-ignition detections Npi in the previous trip is less than the threshold value Npiref, the fuel increase flag Ff is held at a value of 0, and this routine is terminated. On the other hand, when the number of pre-ignition detections Npi in the previous trip is equal to or greater than the threshold value Npiref, the fuel increase flag Ff is switched to a value of 1 (step S140), and this routine is terminated. As described above, when the fuel increase flag Ff is a value of 0, the predetermined increase correction is not performed in the current trip, and when the fuel increase flag Ff is a value of 1, the predetermined increase correction is performed in the current trip. When the number of pre-ignition detections Npi in the previous trip is equal to or greater than the threshold value Npiref, a predetermined increase correction is performed in the current trip to suppress the temperature rise in the combustion chamber 29 of the engine 12 and suppress the occurrence of pre-ignition.

Here, the threshold value Npiref will be explained. The threshold value Npiref is a threshold value used to determine whether or not the number of occurrences of pre-ignition in the previous trip is expected to be relatively high, taking into account the degree of deterioration of the engine oil. This threshold value Npiref can be obtained by applying the mileage Loc after the engine oil change to a threshold setting map. The threshold setting map is predetermined as the relationship between the mileage Loc after the engine oil change and the threshold value Npiref, and is stored in the ROM or flash memory of the electronic control unit 70. FIG. 3 is an explanatory diagram showing an example of a threshold setting map. As shown in the figure, the threshold value Npiref is set to be higher as the mileage Loc after the engine oil change is longer. The longer the mileage Loc after the engine oil change is, the more the engine oil deteriorates, and the more likely pre-ignition occurs. For this reason, if a relatively small uniform value (e.g., several times) is used as the threshold value Npiref, as the deterioration of the engine oil progresses, the number of times Npi that pre-ignition was detected in the previous trip will be more likely to exceed the threshold value Npiref, making it easier to perform the specified increase correction in the current trip and causing fuel economy to deteriorate. In contrast, in the embodiment, the threshold value Npiref is set so that it increases as the mileage Loc after the engine oil change increases, making it possible to more appropriately determine whether or not to perform the specified increase correction in the current trip based on the degree of engine oil deterioration. In other words, when the mileage increases and the engine oil deteriorates, making it easier for pre-ignition of the engine 12 to occur, it is possible to prevent the specified increase correction from being easily performed in the current trip. As a result, it is possible to prevent fuel economy from deteriorating.

When the fuel increase flag Ff is set to a value of 1 in step S100, it is determined that an increase correction was made to the fuel injection amount in the previous trip, and data such as the oil change flag Foc and the maintenance tool flag Fm are input (step S150). Here, the oil change flag Foc is set to a value of 0 as an initial value at the end of each trip, and is switched to a value of 1 when the engine oil is changed at a dealer or the like between the end of the previous trip and the start of the current trip (when the operator registers this using a tool or the like). The oil change flag Foc is input with a value set by an oil change flag setting routine (not shown) executed by the electronic control unit 70. The maintenance tool flag Fm is set to a value of 0 as an initial value at the end of each trip, and is switched to a value of 1 when the operator performs a predetermined operation using a maintenance tool or the like at a dealer or the like between the end of the previous trip and the start of the current trip. The maintenance tool flag Fm is input with a value set by a diagnosis flag setting routine (not shown) executed by the electronic control unit 70.

Once the data has been input in this manner, the values of the input oil change flag Foc and maintenance tool flag Fm are checked (steps S160, S170). If both the oil change flag Foc and the maintenance tool flag Fm have a value of 0, the fuel increase flag Ff is held at a value of 1 and this routine ends. On the other hand, if at least one of the oil change flag Foc and the maintenance tool flag Fm has a value of 1, the fuel increase flag Ff is switched to a value of 0 (step S180) and this routine ends. Switching the fuel increase flag Ff to a value of 0 in this manner means that the specified increase correction will not be performed for the current trip.

FIG. 4 is an explanatory diagram showing an example of the detection counter Cpi, the oil change flag Foc, and the fuel increase flag Ff for the first to fourth trips. As shown in the figure, the detection counter Cpi is counted up each time pre-ignition of the engine 12 is detected in the first trip. Then, at the start of the second trip (time t11), when the number of pre-ignition detections Npi, for which the value of the detection counter Cpi at that time is set, is equal to or greater than the threshold value Npiref, the fuel increase flag Ff is switched from value 0 to value 1. This allows a predetermined increase correction to be performed in the second trip. In the embodiment, the threshold value Npiref is set based on the mileage Loc after the engine oil change, so that it is possible to more appropriately determine whether or not to perform a predetermined increase correction in the current trip, taking into account the degree of deterioration of the engine oil. Then, at the start of the third trip (time t12), when the oil change flag Foc is value 0, the fuel increase flag Ff is held at value 1. This allows a predetermined increase correction to be performed in the third trip as well. If the engine oil is changed between the third and fourth trips and the oil change flag Foc changes from value 0 to value 1, then at the start of the fourth trip (time t13), the fuel increase flag Ff changes from value 1 to value 0. As a result, the specified increase correction is not performed in the fourth trip.

In the automobile 10 of the embodiment described above, the threshold value Npiref is set based on the mileage Loc after the engine oil was changed, and when the number of times Npi that pre-ignition was detected in the previous trip is equal to or greater than the threshold value Npiref, a predetermined increase correction is performed in the current trip. By setting the threshold value Npiref based on the mileage Loc after the engine oil was changed, it is possible to more appropriately determine whether or not to perform the predetermined increase correction in the current trip, taking into account the degree of deterioration of the engine oil. In other words, when the mileage is long and the engine oil deteriorates, making it easier for pre-ignition of the engine 12 to occur, it is possible to suppress the ease with which the predetermined increase correction is performed in the current trip. As a result, it is possible to suppress a deterioration in fuel efficiency.

In the embodiment of the automobile 10, the electronic control unit 70 executes the fuel increase flag setting routine of FIG. 2. However, instead of this, the electronic control unit 70 may execute the fuel increase flag setting routine of FIG. 5. The routine of FIG. 5 is the same as the routine of FIG. 2 except for the addition of the processing of step S115. Therefore, the same step numbers are used for the processing of the routine of FIG. 5 that is the same as the routine of FIG. 2, and detailed explanations thereof will be omitted.

In the fuel increase flag setting routine of FIG. 5, when data is input in step S110, the input mileage Loc after the engine oil change is compared with the threshold Locref (step S115). When the mileage Loc after the engine oil change is less than the threshold Locref, the above-mentioned processing from step S120 onwards is executed. On the other hand, when the mileage Loc after the engine oil change is equal to or greater than the threshold Locref, the fuel increase flag Ff is switched to a value of 1 (step S140) regardless of the number of times pre-ignition was detected in the previous trip Npi, and this routine is terminated. Here, the threshold Locref is a threshold used to determine whether the deterioration of the engine oil is assumed to have progressed sufficiently, and for example, about hundreds of thousands of km is used. When the deterioration of the engine oil progresses sufficiently, the number of occurrences of pre-ignition in each trip tends to be relatively high. For this reason, in this modified example, when engine oil deterioration has progressed sufficiently, a predetermined increase correction is performed in the current trip to protect the engine 12, regardless of the number of times Npi pre-ignition was detected in the previous trip.

In the embodiment of the automobile 10, when the number of times pre-ignition was detected in the previous trip Npi is equal to or greater than the threshold value Npiref, a predetermined increase correction is performed in the current trip. Here, even if the predetermined increase correction is performed in the current trip, if the number of times pre-ignition was detected in that trip Npi is equal to or greater than a threshold value Npiref2 that is greater than the threshold value Npiref, restrictions may be imposed on the required load rate KL* and the target intake air volume Qa* in the next trip. Here, like the threshold value Npiref, the threshold value Npiref2 may be set to be greater the longer the mileage Loc after the engine oil change. Note that when restrictions are imposed on the required load rate KL* and the target intake air volume Qa*, the predetermined fuel increase may not be performed.

In the embodiment, the vehicle 10 is in the form of a typical automobile that runs using power from an engine 12. However, the vehicle may also be in the form of a parallel or series type hybrid automobile that has an engine and a motor.

The following explains the relationship between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem. In the embodiment, the engine 12 corresponds to the "engine" and the electronic control unit 70 corresponds to the "control device."

The correspondence between the main elements of the Examples and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the Examples are examples for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Means for Solving the Problem column.

The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the spirit of the present invention.

The present invention can be used in the vehicle manufacturing industry, etc.

10 automobile, 12 engine, 14 crankshaft, 14a crank position sensor, 15 water temperature sensor, 16 cam position sensor, 22 air cleaner, 23 intake pipe, 23a air flow meter, 23b temperature sensor, 24 throttle valve, 24a throttle position sensor, 26 fuel injection valve, 28 intake valve, 29 combustion chamber, 30 spark plug, 32 piston, 33 exhaust valve, 34 exhaust pipe, 35 purification device, 37 front air-fuel ratio sensor, 38 rear air-fuel ratio sensor, 60 transmission, 62 differential gear, 64a, 64b drive wheels, 70 electronic control unit, 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 Vehicle speed sensor

Claims (1)

A vehicle including an engine having a fuel injection valve and a control device that controls the engine,
when the number of occurrences of pre-ignition of the engine in a previous trip from when an ignition switch was turned on to when it was turned off is equal to or greater than a threshold value, the control device executes an increase correction to the fuel injection amount from the fuel injection valve in the current trip ,
The threshold value is set to be larger when the mileage after the engine oil change is long than when the mileage is short.
vehicle.

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