JP7655167B2 - Engine equipment - Google Patents

Description

The present invention relates to an engine device, and more specifically, to an engine device equipped with a particulate matter removal filter that removes particulate matter contained in the engine exhaust.

Conventionally, an engine system of this type has been proposed that includes an engine, a purification device that purifies the engine exhaust, and a filter that removes particulate matter from the engine exhaust (see, for example, Patent Document 1). In this engine system, when it is determined that a certain amount of particulate matter has accumulated on the filter, a lean regeneration process is carried out in which the filter is heated to a predetermined temperature or higher, the waste atmosphere is made lean, and the filter is regenerated.

JP 2015-222027 A

In the above-mentioned engine device, when the engine is operated in the light load region during the lean regeneration process, the lean regeneration process is interrupted to prevent engine misfires and other problems. If the lean regeneration process is interrupted and then restarted, the air-fuel ratio switches between rich and lean states, accelerating the deterioration of the catalyst in the purification device that purifies the engine exhaust.

The main purpose of the engine device of the present invention is to suppress deterioration of the catalyst in the purification device.

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

The engine device of the present invention comprises:
The engine,
A purification catalyst for purifying exhaust gas from the engine;
a particulate matter removal filter for removing particulate matter contained in exhaust gas from the engine;
A control device for controlling the engine;
An engine device comprising:
When regenerating the particulate matter removal filter, the control device performs air-fuel ratio control by using an air-fuel ratio obtained by applying the engine speed and the load rate to an air-fuel ratio setting map in which a relationship between the engine speed, the load rate, and the air-fuel ratio is predetermined, as a target air-fuel ratio.
It is characterized by:

In the engine device of the present invention, when regenerating the particulate matter removal filter that removes particulate matter contained in the engine exhaust, the air-fuel ratio is controlled by using as a target air-fuel ratio the air-fuel ratio obtained by applying the engine speed and load rate to an air-fuel ratio setting map in which the relationship between the engine speed, load rate, and air-fuel ratio is predetermined. Therefore, by setting a lean air-fuel ratio in the entire range of the air-fuel ratio setting map, it is possible to prevent the air-fuel ratio from becoming rich or lean depending on the engine speed and load rate. As a result, it is possible to prevent the deterioration of the catalyst in the purification device from progressing due to the fuel ratio being frequently switched between rich and lean states.

In the engine device of the present invention, the air-fuel ratio setting map may be set to a weak lean region in the low rotation speed region where the engine rotation speed is relatively low and in the low load rate region where the load rate is relatively small. In this way, it is possible to suppress problems such as misfires even when the engine is operated at a low load. Here, the weak lean region is a region where the air-fuel ratio is closer to the theoretical air-fuel ratio on the lean side than in a region that is not a weak lean region. Note that in the low rotation speed region, the value may be closer to the theoretical air-fuel ratio on the lean side as the engine rotation speed becomes smaller, and in the low load rate region, the value may be closer to the theoretical air-fuel ratio on the lean side as the load rate becomes smaller.

In the engine device of the present invention, the air-fuel ratio setting map may be set to a slightly lean region in the high rotation speed region where the engine rotation speed is relatively high and in the high load rate region where the load rate is relatively large. In this way, NOx can be suppressed when the engine is operated under high load. In the high rotation speed region, the higher the engine rotation speed, the closer to the theoretical air-fuel ratio on the lean side, and in the high load rate region, the higher the load rate, the closer to the theoretical air-fuel ratio on the lean side, may be set.

1 is a schematic diagram showing the configuration of an automobile 10 equipped with an engine device 11 according to an embodiment of the present invention. 4 is a flowchart showing an example of a lean regeneration processing routine executed by an electronic control unit 70. FIG. 4 is an explanatory diagram showing an example of an air-fuel ratio setting map;

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 equipped with an engine device 11 according to an 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, which changes the speed of the power from the engine 12 and transmits it to the drive wheels 64a, 64b, and an electronic control unit 70 that controls the entire automobile 10. Here, the transmission 60 may be a stepped transmission or a continuously variable transmission. The engine device 11 of the embodiment mainly includes the engine 12 and the electronic control unit 70.

The engine 12 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel. The engine 12 draws in air cleaned by the air cleaner 22 into the intake pipe 23, and passes it through the throttle valve 24 and the surge tank 25 in that order, while injecting fuel from the fuel injection valve 26 downstream of the surge tank 25 of the intake pipe 23 to mix the air and fuel. The mixture is then drawn into the combustion chamber 29 via the intake valve 28, and explosively combusted by an electric spark from the ignition plug 30. The reciprocating motion of the piston 32, which is pushed down by the energy of the explosive combustion, is converted into the rotational motion of the crankshaft 14. The exhaust gas discharged from the combustion chamber 29 into the exhaust pipe 33 through the exhaust valve 31 is discharged into the outside air via the purification device 34 and the PM filter 38. The purification device 34 has a purification catalyst (three-way catalyst) 34a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in the exhaust. The PM filter 38 is made of ceramics, stainless steel, or other porous filters, and captures particulate matter (PM) such as soot in the exhaust gas.

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, and input/output ports. Signals from various sensors required for controlling the operation of the engine 12 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 40 that detects the rotational position of the crankshaft 14 of the engine 12, and the cooling water temperature Tw from the water temperature sensor 42 that detects the temperature of the cooling water of the engine 12. Examples of signals input to the electronic control unit 70 include the crank angle θcr from the crank position sensor 40 that detects the rotational position of the intake camshaft that opens and closes the intake valve 28 and the cam angles θci and θco from the cam position sensor 44 that detects the rotational position of the exhaust camshaft that opens and closes the exhaust valve 31. Examples of signals input to the electronic control unit 70 include the throttle opening TH from the throttle position sensor 46 that detects the position of the throttle valve 24, the intake air volume Qa from the air flow meter 48 attached upstream of the throttle valve 24 of the intake pipe 23, the intake air temperature Ta from the temperature sensor 49 attached upstream of the throttle valve 24 of the intake pipe 23, and the surge pressure Ps, which is the pressure in the surge tank 25, from the pressure sensor 58 attached to the surge tank 25. Other examples include the air-fuel ratio AF from the air-fuel ratio sensor 35a attached upstream of the purification device 34 of the exhaust pipe 33, the oxygen signal O2 from the oxygen sensor 35b attached between the purification device 34 of the exhaust pipe 33 and the PM filter 38, and the differential pressure ΔP from the differential pressure sensor 38a attached upstream and downstream of the PM filter 38. Other examples include 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. Other examples include 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.

Various control signals for controlling the operation of the engine 12 are output from the electronic control unit 70 via an output port. Examples of signals output from the electronic control unit 70 include a control signal to the throttle motor 36 that adjusts the position of the throttle valve 24, a control signal to the fuel injector 26, and a control signal to the spark plug 30. Another example is a control signal to the transmission 60.

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 40. The electronic control unit 70 also calculates the load factor KL of the engine 12 (the ratio of the volume of air actually taken in one cycle to the stroke volume per cycle of the engine 12) based on the intake air amount Qa from the air flow meter 48 and the rotation speed Ne of the engine 12. Furthermore, the electronic control unit 70 calculates the PM accumulation amount Qpm as the accumulation amount of particulate matter accumulated in the PM filter 38 based on the differential pressure ΔP from the differential pressure sensor 38a, and calculates the temperature Tf of the PM filter 38 based on the rotation speed Ne of the engine 12 and the load factor KL.

In an automobile 10 equipped with the engine device 11 of the embodiment thus configured, the electronic control unit 70 sets the target gear Gs* of the transmission 60 based on the accelerator opening Acc and the vehicle speed V, and controls the transmission 60 so that the gear Gs of the transmission 60 becomes the target gear Gs*. The electronic control unit 70 also sets the target torque Te* of the engine 12 based on the accelerator opening Acc, the vehicle speed V, and the gear Gs of the transmission 60, and performs operation control of the engine 12 (e.g., intake air amount control, fuel injection control, ignition control, etc.) so that the engine 12 is operated based on the target torque Te*.

In addition, in the automobile 10, when regeneration of the PM filter 38 is required, a regeneration process of the PM filter 38 is performed. Here, the time when regeneration of the PM filter 38 is required can be, for example, when the PM accumulation amount Qpm is equal to or greater than the threshold value Qref. The regeneration process of the PM filter 38 is performed, for example, by executing air-fuel ratio control so that the air-fuel ratio of the mixture supplied to the engine 12 is lean, whereby air (oxygen) is supplied to the PM filter 38 and the particulate matter accumulated in the PM filter 38 reacts with the oxygen (the particulate matter is burned).

Next, the operation of the automobile 10 equipped with the engine device 11 of the embodiment thus configured, particularly the operation when the PM filter 38 is being regenerated, will be described. FIG. 2 is a flowchart showing an example of a lean regeneration processing routine executed by the electronic control unit 70. This routine is executed repeatedly when the PM filter 38 is being regenerated.

2 is executed, the electronic control unit 70 inputs the engine 12 rotation speed Ne and the load factor KL (step S100). Next, the air-fuel ratio obtained by applying the input engine 12 rotation speed Ne and load factor KL to the air-fuel ratio setting map is set as the target air-fuel ratio AF* (step S110), and this routine ends. An example of the air-fuel ratio setting map is shown in FIG. 3. As shown in the figure, in the air-fuel ratio setting map of the embodiment, the low rotation speed region where the engine 12 rotation speed Ne is relatively low and the high rotation speed region where the load factor KL is relatively small and the high load factor region where the load factor KL is relatively large are set as weak lean regions, and the region excluding the low rotation speed region and the high rotation speed region of the engine 12 rotation speed Ne and the low load factor region and the high load factor region of the load factor KL (the central region in FIG. 3) is set as the normal lean region. In the normal lean region, the air-fuel ratio is set so that the fuel injection amount is about 5% less than the theoretical air-fuel ratio (e.g., 15.0 to 15.4), and in the weak lean region, the air-fuel ratio is set so that the fuel injection amount is about 1% to 3% less than the theoretical air-fuel ratio (e.g., 14.8 to 15.0).

In the weak lean region, the air-fuel ratio may be a predetermined specific value among the air-fuel ratios in which the fuel injection amount is about 1% to 3% less than the theoretical air-fuel ratio described above, but in the low rotation region of the engine 12, the smaller the rotation speed Ne, the closer (smaller) the value to the theoretical air-fuel ratio on the lean side, and in the high rotation region of the engine 12, the larger the rotation speed Ne, the closer (smaller) the value to the theoretical air-fuel ratio on the lean side. In the low load ratio region, the smaller the load rate KL, the closer (smaller) the value to the theoretical air-fuel ratio on the lean side, and in the high load ratio region, the larger the load rate KL, the closer (smaller) the value to the theoretical air-fuel ratio on the lean side. In the normal lean region, the air-fuel ratio may be constant throughout the entire region, but in the low rotation region, high rotation region, low load region, and region close to the high load region, the air-fuel ratio may be changed to be closer to the air-fuel ratio of the weak lean region.

In the engine device 11 mounted on the automobile 10 of the embodiment described above, the air-fuel ratio setting map is set so that the air-fuel ratio is lean in all ranges while the lean regeneration process is being performed, thereby making it possible to suppress interruption and resumption of the lean regeneration process. As a result, it is possible to prevent the air-fuel ratio from becoming rich or lean depending on the engine speed and load factor. As a result, it is possible to suppress the deterioration of the catalyst in the purification device from progressing due to the fuel ratio being frequently switched between rich and lean states.

In the embodiment, the engine device 11 is mounted on an automobile 10, but the engine device 11 may be mounted on a vehicle other than an automobile, or on a moving body other than a vehicle, or may be incorporated into stationary equipment, etc.

The following describes 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", the purification device 34 corresponds to the "purification device", the PM filter 38 corresponds to the "particulate matter removal filter", 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 scope of the invention.

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

10 automobile, 12 engine, 14 crankshaft, 22 air cleaner, 23 intake pipe, 24 throttle valve, 25 surge tank, 26 fuel injection valve, 28 intake valve, 29 combustion chamber, 30 spark plug, 31 exhaust valve, 32 piston, 33 exhaust pipe, 34 purification device, 35a air-fuel ratio sensor, 35b oxygen sensor, 36 throttle motor, 38 PM filter, 38a differential pressure sensor, 40 crank position sensor, 42 water temperature sensor, 44 cam position sensor, 46 throttle position sensor, 48 air flow meter, 49 temperature 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 (2)

The engine,
A purification catalyst for purifying exhaust gas from the engine;
a particulate matter removal filter for removing particulate matter contained in exhaust gas from the engine;
A control device for controlling the engine;
An engine device comprising:
When regenerating the particulate matter removal filter, the control device performs air -fuel ratio control by using, as a target air-fuel ratio, an air-fuel ratio obtained by applying the engine speed and the load rate to an air-fuel ratio setting map in which a relationship between the engine speed, the load rate, and the air-fuel ratio is previously determined so that the air-fuel ratio is lean over an entire range,
In the air-fuel ratio setting map, a low rotation speed region where the engine rotation speed is relatively low and/or a low load factor region where the load factor is relatively low are set to a slight lean region.
Engine equipment. 2. The engine device according to claim 1 ,
In the air-fuel ratio setting map, a high rotation speed region in which the engine rotation speed is relatively high and/or a high load factor region in which the load factor is relatively high are set to a slight lean region.
Engine equipment.

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