JP2022023344A - Engine device - Google Patents

Abstract

To increase a purge rate in a shorter time after switching from a supercharging region to a natural intake region.SOLUTION: An engine device includes: an engine; a supercharger; an evaporated fuel treatment device; and a control device for controlling a purge control valve on the basis of a required purge rate gradually changing toward a target purge rate when performing purge for supplying evaporated fuel gas to an intake pipe. The control device sets the required purge rate so as to be smaller in a supercharging region than in a natural intake region when purge is performed, and increases the required purge rate when the supercharging region is switched to the natural intake region.SELECTED DRAWING: Figure 7

Description

The present invention relates to an engine device.

Conventionally, as an engine device of this type, a first purge passage for purging the evaporated fuel gas containing the evaporated fuel on the downstream side of the throttle valve in the intake pipe of the engine and a boost pressure from the supercharger are used to be negative. A second purge passage that purges the vaporized fuel gas upstream of the turbocharger compressor in the intake pipe by an ejector that generates pressure, and a first purge passage and a second purge passage that purge the evaporated fuel gas generated in the fuel tank. A supply passage and a purge control valve provided in the supply passage have been proposed (see, for example, Patent Document 1). In this engine device, the intake pipe pressure downstream of the throttle valve of the intake pipe is compared with the pressure generated by the ejector, and whether the purge is performed through the first purge passage or the second purge passage. Is detected. Then, when the purge passage is switched between the first purge passage and the second purge passage, the control characteristic data used for controlling the purge control valve is transferred to the first control characteristic data and the second purge passage suitable for the first purge passage. Switch with the suitable second control characteristic data.

Japanese Unexamined Patent Publication No. 2019-052561

In such an engine device, when purging in the supercharged area (when the purge passage is the second purge passage), compared to when performing the purge in the naturally aspirated region (when the purge passage is the first purge passage). As a result, the air-fuel ratio of the engine tends to become unstable due to the large path volume until the evaporated fuel gas reaches the combustion chamber of the engine, and the fluctuation of the supercharging pressure and the generated pressure due to the ejector. For this reason, it is conceivable to limit the purge rate in the supercharged area compared to the naturally aspirated area, but in this case, the time until the purge rate increases to some extent after switching from the supercharged area to the naturally aspirated area. May be longer.

The main purpose of the engine device of the present invention is to increase the purge rate in a shorter time after switching from the supercharging region to the naturally aspirated region.

The engine device of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The engine device of the present invention
An engine that has a throttle valve located in the intake pipe and outputs power using fuel supplied from the fuel tank.
A turbocharger having a compressor arranged on the upstream side of the throttle valve of the intake pipe, and
Evaporated fuel gas containing evaporative fuel generated in the fuel tank is branched into a first purge passage and a second purge passage connected to the downstream side of the throttle valve of the intake pipe and supplied to the intake pipe. An intake port is connected to a supply passage and a recirculation passage from between the compressor of the intake pipe and the throttle valve, and an exhaust port is connected to the upstream side of the compressor of the intake pipe and the second purge passage. An evaporative fuel treatment device having an ejector to which a suction port is connected and a purge control valve provided in the supply passage.
A control device that controls the purge control valve based on a required purge rate that slowly changes toward the target purge rate when performing a purge that supplies the evaporated fuel gas to the intake pipe.
It is an engine device equipped with
When executing the purge, the control device sets the required purge rate so as to be smaller than the naturally aspirated region in the supercharged region, and further switches from the supercharged region to the naturally aspirated region. When this happens, the required purge rate is increased.
The gist is that.

In the engine device of the present invention, when performing a purge for supplying evaporative fuel gas to the intake pipe, the purge control valve is controlled based on the required purge rate that slowly changes toward the target purge rate. In this case, when executing purging, the required purge rate is set so that it is smaller than the naturally aspirated area in the supercharged area, and further, when the supercharged area is switched to the naturally aspirated area, the required purge rate is set. Raise. As a result, the purge rate can be increased in a shorter time after switching from the supercharging region to the naturally aspirated region.

In the engine device of the present invention, when the control device switches from the supercharged area to the naturally aspirated area, the required purge rate is increased by using the restart purge rate when the purge is restarted in the naturally aspirated area. It may be a thing. In this way, the required purge rate can be increased more appropriately when switching from the supercharged region to the naturally aspirated region. In this case, the control device sets the restart purge rate when restarting the purge in the naturally aspirated region based on the maximum value of the required purge rate in the naturally aspirated region in the current trip of the mounted vehicle. It may be a thing.

In the engine device of the present invention, when the control device switches from the supercharged area to the naturally aspirated area, the required purge rate is increased so that the longer the execution time of the purge in the supercharged area is, the smaller the required purge rate is. It may be the one to do. In this way, the required purge rate can be increased more appropriately when switching from the supercharged region to the naturally aspirated region. In this case, the control device counts up the counter when the purge is executed in the supercharged area, holds the counter when the purge is not executed in the supercharged area, and holds the counter in the naturally aspirated area. It may be reset, and the value immediately before the reset of the counter may be set as the execution time of the purge in the supercharging area.

In the engine device of the present invention, the control device estimates that the throttle rear pressure is in the naturally aspirated region when the throttle rear pressure is less than the threshold value, and determines that the control device is in the supercharging region when the throttle rear pressure is equal to or more than the threshold value. In the estimation process for estimation, when the throttle post-pressure reaches from the threshold value or more to the threshold value or less, the estimation that the turbocharging region may be continued until a predetermined time elapses. In this way, it is possible to more appropriately estimate whether it is a naturally aspirated region or a supercharged region.

It is a block diagram which shows the outline of the structure of the engine device 10. It is explanatory drawing which shows an example of the input / output signal of an electronic control unit 70. It is a flowchart which shows an example of a fuel injection control routine. It is a flowchart which shows an example of a purge correction amount setting routine. It is explanatory drawing which shows an example of the map for setting the update amount. This is the first half of the flowchart showing an example of the purge control routine. This is the second half of the flowchart showing an example of the purge control routine. It is a flowchart which shows an example of a supercharging area determination routine. It is explanatory drawing which shows an example of the state of the surge pressure Ps and the supercharging area flag Fc. It is explanatory drawing which shows an example of the map for full-open purge flow rate estimation. This is the first half of the flowchart showing an example of a subprocessing routine. This is the second half of the flowchart showing an example of a subprocessing routine. It is a flowchart which shows an example of the control purge determination routine. It is explanatory drawing which shows an example of the map for setting the ejector pressure. It is explanatory drawing which shows an example of the offset amount setting map when the cross-sectional area of the 2nd purge passage 63 is smaller than the cross-sectional area of the 1st purge passage 62. It is explanatory drawing which shows an example of the state of the presence / absence of execution of a purge, the control purge flag Fpd, the purge non-execution counter Cnp, the downstream purge integration counter Cpdn, and the upstream purge execution counter Cpup. It is explanatory drawing which shows an example of the map for setting the upper limit guard value. It is explanatory drawing which shows an example of the map for setting a reflection coefficient. It is explanatory drawing which shows an example of the map for setting a temporary lower limit purge rate. It is explanatory drawing which shows an example of the state of the surge pressure Ps, the supercharging area flag Fc, the required purge rate Rprq, and the storage value Rprssr for the restart purge rate.

Next, an embodiment for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of an engine device 10 as an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an example of an input / output signal of an electronic control unit 70. The engine device 10 of the embodiment is mounted on a general vehicle traveling by using the power from the engine 12 and various hybrid vehicles equipped with a motor in addition to the engine 12, and as shown in FIGS. 1 and 2. It includes an engine 12, a supercharger 40, an evaporative fuel processing device 50, and an electronic control unit 70.

The engine 12 is configured as an internal combustion engine that outputs power using fuel such as gasoline or light oil supplied from the fuel tank 11. The engine 12 sucks the air cleaned by the air cleaner 22 into the intake pipe 23 and passes it through the intercooler 25, the throttle valve 26, and the surge tank 27 in this order. Then, fuel is injected from the in-cylinder injection valve 28 attached to the combustion chamber 30 to the air sucked into the combustion chamber 30 through the intake valve 29 to mix the air and the fuel, and the air is exploded by the electric spark from the spark plug 31. Burn. The engine 12 converts the reciprocating motion of the piston 32 pushed down by the energy generated by such explosive combustion into the rotational motion of the crankshaft 14. The exhaust gas discharged from the combustion chamber 30 to the exhaust pipe 35 via the exhaust valve 34 is a catalyst (three-way catalyst) that purifies harmful components of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). ) Is discharged to the outside air through the purification devices 37 and 38. Fuel is supplied to the in-cylinder injection valve 28 from the fuel tank 11 via the feed pump 11p, the low-pressure side fuel passage 17, the high-pressure pump 18, and the high-pressure side fuel passage 19. The high-pressure pump 18 is driven by power from the engine 12 to pressurize the fuel in the low-pressure side fuel passage 17 and supply it to the high-pressure side fuel passage 19.

The turbocharger 40 is configured as a turbocharger and includes a compressor 41, a turbine 42, a rotary shaft 43, a wastegate valve 44, and a blow-off valve 45. The compressor 41 is arranged on the upstream side of the intercooler 25 of the intake pipe 23. The turbine 42 is arranged on the upstream side of the purification device 37 of the exhaust pipe 35. The rotary shaft 43 connects the compressor 41 and the turbine 42. The wastegate valve 44 is provided in the bypass pipe 36 connecting the upstream side and the downstream side of the turbine 42 in the exhaust pipe 35, and is controlled by the electronic control unit 70. The blow-off valve 45 is provided in the bypass pipe 24 connecting the upstream side and the downstream side of the compressor 41 in the intake pipe 23, and is controlled by the electronic control unit 70.

In the turbocharger 40, by adjusting the opening degree of the wastegate valve 44, the distribution ratio between the displacement flowing through the bypass pipe 36 and the displacement flowing through the turbine 42 is adjusted, and the rotational driving force of the turbine 42 is adjusted. Then, the amount of compressed air by the compressor 41 is adjusted, and the supercharging pressure (intake pressure) of the engine 12 is adjusted. Here, in detail, the distribution ratio is adjusted so that the smaller the opening degree of the wastegate valve 44, the smaller the displacement through the bypass pipe 36 and the larger the displacement through the turbine 42. When the wastegate valve 44 is fully opened, the engine 12 can operate in the same manner as a naturally aspirated type engine without a supercharger 40.

Further, in the turbocharger 40, when the pressure on the downstream side of the compressor 41 in the intake pipe 23 is higher than the pressure on the upstream side to some extent, the blow-off valve 45 is opened to cause a surplus on the downstream side of the compressor 41. The pressure can be released. The blow-off valve 45 is configured as a check valve that opens when the pressure on the downstream side of the compressor 41 in the intake pipe 23 becomes higher than the pressure on the upstream side to some extent, instead of the valve controlled by the electronic control unit 70. It may be done.

The evaporative fuel processing device 50 is a device for purging to supply the evaporative fuel gas (purge gas) generated in the fuel tank 11 to the intake pipe 23 of the engine 12, and is an introduction passage 52, an on-off valve 53, and a bypass. Passage 54, relief valves 55a, 55b, canister 56, common passage 61, first purge passage 62, second purge passage 63, buffer portion 64, purge control valve 65, check valve 66, 67, a return passage 68, and an ejector 69 are provided. The "supply passage" of the embodiment corresponds to the introduction passage 52 and the common passage 61.

The introduction passage 52 is connected to the fuel tank 11 and the canister 56. The on-off valve 53 is provided in the introduction passage 52, and is configured as a normally closed type solenoid valve. The on-off valve 53 is controlled by the electronic control unit 70.

The bypass passage 54 has branch portions 54a and 54b that bypass the fuel tank 11 side and the canister 56 side of the opening / closing valve 53 of the introduction passage 52 and branch into two to join. The relief valve 55a is provided at the branch portion 54a and is configured as a check valve, and is opened when the pressure on the fuel tank 11 side becomes higher to some extent than the pressure on the canister 56 side. The relief valve 55b is provided in the branch portion 54b and is configured as a check valve, and opens when the pressure on the canister 56 side becomes to some extent higher than the pressure on the fuel tank 11 side.

The canister 56 is connected to the introduction passage 52 and is open to the atmosphere through the atmosphere opening passage 57. The inside of the canister 56 is filled with an adsorbent such as activated carbon capable of adsorbing the evaporative fuel from the fuel tank 11. An air filter 58 is provided in the air opening passage 57.

The common passage 61 is connected to the vicinity of the canister 56 of the introduction passage 52, and branches to the first purge passage 62 and the second purge passage 63 at the branch point 61a. The first purge passage 62 is connected between the throttle valve 26 of the intake pipe 23 and the surge tank 27. The second purge passage 63 is connected to the suction port of the ejector 69.

The buffer portion 64 is provided in the common passage 61. The inside of the buffer portion 64 is filled with an adsorbent such as activated carbon capable of adsorbing the evaporative fuel from the fuel tank 11 and the canister 56. The purge control valve 65 is provided on the branch point 61a side of the buffer portion 64 of the common passage 61. The purge control valve 65 is configured as a normally closed type solenoid valve. The purge control valve 65 is controlled by the electronic control unit 70.

The check valve 66 is provided near the branch point 61a of the first purge passage 62. The check valve 66 allows the flow of the evaporated fuel gas (purge gas) containing the evaporated fuel in the direction from the common passage 61 side of the purge passage 60 to the first purge passage 62 (intake pipe 23) side, and evaporates in the reverse direction. Prohibit the flow of fuel gas. The check valve 67 is provided near the branch point 61a of the second purge passage 63. The check valve 67 allows the flow of the evaporated fuel gas in the direction from the common passage 61 side of the purge passage 60 to the second purge passage 63 (ejector 69) side, and prohibits the flow of the evaporated fuel gas in the reverse direction.

The return passage 68 is connected between the compressor 41 of the intake pipe 23 and the intercooler 25, and the intake port of the ejector 69. The ejector 69 has an intake port, a suction port, and an exhaust port. The intake port of the ejector 69 is connected to the return passage 68, the suction port is connected to the second purge passage 63, and the exhaust port is connected to the upstream side of the compressor 41 of the intake pipe 23. .. The tip of the intake port is tapered.

In this ejector 69, when the supercharger 40 is operating (when the pressure between the compressor 41 of the intake pipe 23 and the intercooler 25 becomes positive pressure), the pressure between the intake port and the exhaust port becomes positive. A difference occurs, and recirculation intake air (intake air recirculated from the downstream side of the compressor 41 of the intake pipe 23 via the recirculation passage 68) flows from the intake port to the exhaust port. At this time, the reflux intake air is depressurized at the tip of the intake port, and a negative pressure is generated around the tip. Then, due to the negative pressure, the evaporated fuel gas is sucked from the second purge passage 63 through the suction port, and the evaporated fuel gas is upstream from the compressor 41 of the intake pipe 23 through the exhaust port together with the negative pressure recirculation intake. Supplied to the side.

The evaporative fuel processing device 50 configured in this way basically operates as follows. When the pressure on the downstream side of the throttle valve 26 of the intake pipe 23 (surge pressure Ps described later) is negative and the on-off valve 53 and the purge control valve 65 are open, the check valve 66 is opened. Then, the evaporated fuel gas (purge gas) generated in the fuel tank 11 and the evaporated fuel gas desorbed from the canister 56 pass through the introduction passage 52, the common passage 61, and the first purge passage 62 from the throttle valve 26 of the intake pipe 23. Is also supplied to the downstream side. Hereinafter, this is referred to as "downstream purge". At this time, if the pressure between the compressor 41 of the intake pipe 23 and the intercooler 25 (the boost pressure Pc described later) is negative pressure or zero, the ejector 69 does not operate, so the check valve 66 does not open. ..

Further, when the pressure (supercharging pressure Pc) between the compressor 41 of the intake pipe 23 and the intercooler 25 is positive and the on-off valve 53 and the purge control valve 65 are open, the ejector 69 operates. Then, the check valve 67 is opened, and the evaporated fuel gas is supplied to the upstream side of the compressor 41 of the intake pipe 23 via the introduction passage 52, the common passage 61, the second purge passage 63, and the ejector 69. Hereinafter, this is referred to as "upstream purge". At this time, the check valve 66 opens or closes according to the pressure (surge pressure Ps) downstream of the throttle valve 26 of the intake pipe 23.

Therefore, in the evaporated fuel processing device 50, the pressure on the downstream side of the throttle valve 26 of the intake pipe 23 (surge pressure Ps) and the pressure between the compressor 41 of the intake pipe 23 and the intercooler 25 (supercharging pressure Pc). Depending on the purge, only the downstream purge may be performed, only the upstream purge may be performed, or both the downstream purge and the upstream purge may be performed.

The electronic control unit 70 is configured as a microprocessor centered on a CPU, and in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, and a non-volatile flash for storing and holding data. It has a memory, input / output port, and communication port. Signals from various sensors are input to the electronic control unit 70 via the input port.

The signals input to the electronic control unit 70 include, for example, the tank internal pressure Ptnk from the internal pressure sensor 11a that detects the pressure in the fuel tank 11, and the crank position sensor 14a that detects the rotational position of the crank shaft 14 of the engine 12. The crank angle θcr, the cooling water temperature Tw from the water temperature sensor 16 that detects the temperature of the cooling water of the engine 12, and the throttle opening TH from the throttle position sensor 26a that detects the opening degree of the throttle valve 26 can be mentioned. Camposition θca from a camposition sensor (not shown) that detects the rotational position of the intake camshaft that opens and closes the intake valve 29 and the exhaust camshaft that opens and closes the exhaust valve 34 can also be mentioned. The intake air amount Qa from the air flow meter 23a installed on the upstream side of the compressor 41 of the intake pipe 23, the intake air temperature Tin from the intake air temperature sensor 23t installed on the upstream side of the compressor 41 of the intake pipe 23, and the intake air. The intake pressure (compressor front pressure) Pin from the intake pressure sensor 23b installed on the upstream side of the compressor 41 of the pipe 23, and the boost pressure sensor 23c installed between the compressor 41 of the intake pipe 23 and the intercooler 25. The boost pressure Pc from can also be mentioned. Surge pressure (throttle post-pressure) Ps from the surge pressure sensor 27a attached to the surge tank 27 and surge temperature Ts from the temperature sensor 27b attached to the surge tank 27 can also be mentioned. The fuel pressure Pfd supplied from the fuel pressure sensor 28a that detects the fuel pressure of the fuel supplied to the in-cylinder injection valve 28 can also be mentioned. The front air-fuel ratio AF1 from the front air-fuel ratio sensor 35a installed on the upstream side of the purification device 37 of the exhaust pipe 35, and the rear air-fuel ratio sensor installed between the purification device 37 and the purification device 38 of the exhaust pipe 35. The rear air-fuel ratio AF2 from 35b can also be mentioned. Examples include the opening degree Opv of the purge control valve 65 from the purge control valve position sensor 65a and the sensor signal Pobd from the OBD sensor (pressure sensor) 63a attached to the second purge passage 63.

Various control signals are output from the electronic control unit 70 via the output port. Examples of the signal output from the electronic control unit 70 include a control signal to the throttle valve 26, a control signal to the in-cylinder injection valve 28, and a control signal to the spark plug 31. A control signal to the wastegate valve 44, a control signal to the blow-off valve 45, and a control signal to the on-off valve 53 can also be mentioned. A control signal to the purge control valve 65 can also be mentioned.

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

In the engine device 10 of the embodiment configured in this way, the electronic control unit 70 controls the intake air amount that controls the opening degree of the throttle valve 26 based on the required load factor KL * of the engine 12, and the in-cylinder injection valve 28. Fuel injection control that controls the fuel injection amount from, ignition control that controls the ignition timing of the ignition plug 31, supercharging control that controls the opening degree of the wastegate valve 44, and purge control that controls the opening degree of the purge control valve 65. And so on. Hereinafter, fuel injection control and purge control will be described. Since the intake air amount control, the ignition control, and the supercharging control do not form the core of the present invention, detailed description thereof will be omitted.

First, fuel injection control will be described. FIG. 3 is a flowchart showing an example of a fuel injection control routine. This routine is repeatedly executed by the electronic control unit 70. When this routine is executed, the electronic control unit 70 inputs data such as the load factor KL of the engine 12 and the purge correction amount β (step S100). Here, as the load factor KL of the engine 12, a value calculated based on the intake air amount Qa and the rotation speed Ne is input. The purge correction amount β is a correction amount related to the above-mentioned downstream purge and upstream purge, and a value set by the purge correction amount setting routine described later is input.

Subsequently, the base injection amount Qfbs of the in-cylinder injection valve 28 is set based on the load factor KL (step S110), the purge correction amount β is added to the set base injection amount Qfbs, and the required injection amount of the in-cylinder injection valve 28 is added. Qf * is set (step S120), the in-cylinder injection valve 28 is controlled using the set required injection amount Qf * (step S130), and this routine is terminated. Here, the base injection amount Qfbs is a base value of the required injection amount Qf * of the in-cylinder injection valve 28 for setting the air-fuel ratio of the air-fuel mixture in the combustion chamber 30 to the required air-fuel ratio AF *. The base injection amount Qfbs is, for example, a unit injection amount of the in-cylinder injection valve 28 for setting the air-fuel ratio of the air-fuel mixture in the combustion chamber 30 to the required air-fuel ratio AF * (injection amount per 1% of the load factor KL). The value calculated as the product of Qfpu and the load factor KL is set.

Next, the process of setting the purge correction amount β used in the fuel injection amount control routine of FIG. 3 will be described using the purge correction amount setting routine of FIG. This routine is repeatedly executed by the electronic control unit 70. When this routine is executed, the electronic control unit 70 first inputs data such as the intake air amount Qa, the front air-fuel ratio AF1, the opening degree Opv of the purge control valve 65, and the required purge rate Rprq (step S200). .. Here, a value detected by the air flow meter 23a is input as the intake air amount Qa. The value detected by the front air-fuel ratio sensor 35a is input to the front air-fuel ratio AF1. The value detected by the purge control valve position sensor 65a is input to the opening degree Opv of the purge control valve 65. The value set by the purge control routine described later is input to the requested purge rate Rprq.

When the data is input in this way, it is determined whether or not the purge is executed by using the input opening degree Opv of the purge control valve 65 (step S210). Then, when it is determined that the purge is not executed, the purge concentration-related value Cp is held (step S220), the purge correction amount β is set to a value 0 (step S230), and this routine is terminated. Here, the purge concentration-related value Cp is a correction coefficient related to the deviation of the air-fuel ratio in the combustion chamber 30 per 1% of the purge rate. The purge concentration-related value Cp is set to a value of 0 as an initial value when the first purge is started in each trip. The "purge concentration" means the concentration of the evaporated fuel in the evaporated fuel gas, and the "purge rate" means the ratio of the evaporated fuel gas to the intake air amount.

When it is determined in step S210 that purging is being executed, the update amount ΔCp of the purge concentration-related value Cp is set based on the front air-fuel ratio AF1 (step S240), and the value is updated to the previous purge concentration-related value (previous Cp). The value to which the amount ΔCp is added is set to the purge concentration-related value Cp (step S250). Here, the update amount ΔCp can be obtained by applying the front air-fuel ratio AF1 to the update amount setting map. The update amount setting map is predetermined by experiments and analysis as the relationship between the front air-fuel ratio AF1 and the update amount ΔCp, and is stored in a ROM or flash memory (not shown). FIG. 5 is an explanatory diagram showing an example of an update amount setting map. As shown in the figure, the renewal amount ΔCp is within the negative range and the positive range when the front air-fuel ratio AF1 is on the rich side and the lean side with respect to the required air-fuel ratio AF *, respectively, and the front air-fuel ratio AF1 and the required air-fuel ratio are empty. The absolute value is set so that the larger the difference from the fuel ratio AF * (the front air-fuel ratio AF1 is separated from the required air-fuel ratio AF *), the larger the absolute value. When the value Cp related to the purge concentration set in this way is negative, it means that the gas passing through the purge control valve 65 contains evaporated fuel, and when the value is 0 or more, the purge control valve is used. It means that the gas passing through 65 does not contain evaporative fuel. This purge concentration-related value Cp is set when the purge concentration is high, such as immediately after the first start or restart of the purge trip, that is, when the front air-fuel ratio AF1 tends to be richer than the required air-fuel ratio AF *. It becomes relatively small (the absolute value as a negative value increases), and then gradually increases as the purge continues and the purge concentration decreases.

Then, the product of the purge concentration-related value Cp, the intake air amount Qa, and the required purge rate Rprq is set to the purge correction amount β (step S260), and this routine is terminated. The purge correction amount β set in this way becomes a negative value when the purge concentration-related value Cp is a negative value, and the larger the absolute value of the purge concentration-related value Cp, the larger the absolute value. The larger the purge rate Rprq, the larger the absolute value. Further, the purge correction amount β becomes a value 0 when the purge concentration-related value Cp is a value 0. Further, the purge correction amount β becomes a positive value when the purge concentration-related value Cp is a positive value, and the larger the absolute value of the purge concentration-related value Cp, the larger the absolute value. The larger Rprq, the larger the absolute value. The smaller the purge correction amount β is, the smaller the required injection amount Qf * is to control the in-cylinder injection valve 28 in the fuel injection control routine of FIG.

Next, purge control will be described. 6 and 7 are flowcharts showing an example of a purge control routine. This routine is repeatedly executed by the electronic control unit 70. When this routine is executed, the electronic control unit 70 first inputs data such as intake air amount Qa, intake pressure Pin, supercharging pressure Pc, surge pressure Ps, purge condition flag Fpc, and supercharging area flag Fc. (Step S300).

Here, a value detected by the air flow meter 23a is input as the intake air amount Qa. The value detected by the intake pressure sensor 23b is input to the intake pressure Pin. The value detected by the boost pressure sensor 23c is input to the boost pressure Pc. The value detected by the surge pressure sensor 27a is input to the surge pressure Ps. The purge condition flag Fpc is a flag in which a value 1 is set when the purge condition is satisfied and a value 0 is set when the purge condition is not satisfied, and the value set by the electronic control unit 70 is input. The flag. As the purge condition, for example, a condition is used in which the operation control of the engine 12 (fuel injection control or the like) is performed and the cooling water temperature Tw is equal to or higher than the threshold value Twref. As the threshold value Twref, about 55 ° C. to 65 ° C. is used. The supercharging area flag Fc is a flag in which a value 0 is set when it is estimated to be a naturally aspirated area, and a value 1 is set when it is estimated to be a supercharging area. The value set by the area determination routine is input. Here, the "naturally aspirated area" means that the purge does not include the upstream purge (only the downstream purge) when performing the purge, and the "supercharged area" is performing the purge. Sometimes it means that the purge includes an upstream purge. "Purge includes upstream purge" means that at least a part of the evaporative fuel gas supplied to the combustion chamber 30 is the evaporative fuel gas supplied through the second purge passage 63. Hereinafter, the description of the purge control routine of FIGS. 6 and 7 will be interrupted, and the supercharging area determination routine of FIG. 8 will be described.

The supercharging area determination routine of FIG. 8 is repeatedly executed by the electronic control unit 70 regardless of whether or not the purge condition is satisfied. Therefore, the supercharged area flag Fc when the purge is not executed becomes a value when it is assumed that the purge is executed. When this routine is executed, the electronic control unit 70 first inputs surge pressures Ps (step S500). Here, a value detected by the surge pressure sensor 27a is input as the surge pressure Ps. Subsequently, the value of the supercharged area flag (previous Fc) set when this routine was executed last time is checked (step S510).

When the value of the previous supercharging area flag (previous Fc) is 0 in step S510, that is, when it is estimated that the engine is in the naturally aspirated area, the surge pressure Ps and the threshold value Psref are compared (step S520). Here, the threshold value Psref is a threshold value used for estimating which of the naturally aspirated region and the supercharged region, is predetermined by experiments and analysis, and is stored in a ROM or flash memory (not shown). As the threshold value Psref, for example, about -6 to -9 kPa is used.

When it is determined in step S520 that the surge pressure Ps is less than the threshold value Psref, it is estimated to be in the naturally aspirated region, a value 0 is set in the supercharging region flag Fc, that is, the value is held at 0 (step S530). End this routine. When it is determined in step S520 that the surge pressure Ps is equal to or higher than the threshold value Psref, it is estimated to be in the supercharging area, and the value 1 is set in the supercharging area flag Fc, that is, the value is switched from 0 to 1 (step S560). ), End this routine.

When the previous supercharging area flag (previous Fc) has a value of 1 in step S510, that is, when it is estimated to be the supercharging area, the surge pressure Ps and the threshold value Psref are compared (step S540). When it is determined that the surge pressure Ps is equal to or higher than the threshold value Psref, it is estimated to be in the supercharging region, a value 1 is set in the supercharging region flag Fc, that is, the value is held at 1 (step S560), and this routine is performed. finish.

When it is determined in step S540 that the surge pressure Ps is less than the threshold value Psref, it is determined whether or not T1 has elapsed for a predetermined time after the surge pressure Ps reaches the threshold value Psref (step S550). The details of the predetermined time T1 will be described later. When it is determined that T1 has not elapsed for a predetermined time after the surge pressure Ps reaches the threshold value Psref, it is estimated to be in the supercharging area, and the value 1 is set in the supercharging area flag Fc, that is, the value is held at 1. (Step S560), this routine is terminated. When it is determined that T1 has elapsed for a predetermined time after the surge pressure Ps reaches less than the threshold value Psref, it is estimated to be in the naturally aspirated region, and the value 0 is set in the supercharging region flag Fc, that is, the value is switched from the value 1 to the value 0. (Step S530), this routine is terminated.

Here, the predetermined time T1 will be described. The predetermined time T1 is the time until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) in the upstream purge and the time until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) in the downstream purge. The difference is predetermined by experiment and analysis. Based on the path volume until the vaporized fuel gas reaches the surge tank 27 (combustion chamber 30) through the second purge passage 63 and the intake pipe 23 in the upstream purge (the second purge passage 63 and substantially the entire intake pipe 23). The path volume (path volume) is the path volume (of the first purge passage 62 and the intake pipe 23) until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) via the first purge passage 62 and the intake pipe 23 in the downstream purge. It is larger than the path volume based on the portion downstream of the throttle valve 26). Therefore, the time required for the evaporated fuel gas to reach the surge tank 27 (combustion chamber 30) in the upstream purge is compared with the time required for the evaporated fuel gas to reach the surge tank 27 (combustion chamber 30) in the downstream purge. Will be long. Therefore, when the surge pressure Ps reaches the threshold value Psref or lower from the threshold value Psref or higher during the purge, the evaporated fuel gas remaining in the second purge passage 63 and the second purge pressure gas for a while. It is assumed that the evaporative fuel gas newly supplied to the purge passage 62 merges on the downstream side of the throttle valve 26 of the intake pipe 23 and is supplied to the surge tank 27 (combustion chamber 30). In the embodiment, based on this, when the supercharging area flag Fc is a value 1, the supercharging area is waited for a predetermined time T1 to elapse after the surge pressure Ps reaches the threshold value Psref or more and becomes less than the threshold value Psref. It was assumed that the flag Fc was switched to the value 0. This makes it possible to more appropriately estimate which of the naturally aspirated region and the supercharged region.

FIG. 9 is an explanatory diagram showing an example of the state of the surge pressure Ps and the supercharging area flag Fc. As shown in the figure, when the supercharging area flag Fc has a value of 0 and the surge pressure Ps reaches the threshold value Psref or more (time t11), the supercharging area flag Fc is switched to the value 1. After that, when the surge pressure Ps reaches the threshold value Psref or less (time t12), the surge pressure Ps is less than the threshold value Psref and the predetermined time T1 elapses (time t13), the supercharging area flag Fc is switched to the value 0.

The supercharging area determination routine of FIG. 8 has been described. Returning to the description of the purge control routine of FIGS. 6 and 7. When data is input in step S300, the value of the purge condition flag Fpc is checked (step S310). When the purge condition flag Fpc is a value 0, that is, when the purge condition is not satisfied, a value 0 is set in the required purge rate Rprq (step S360), and a value 0 is set in the drive duty Ddr of the purge control valve 65. (Step S362), the purge control valve 65 is controlled using the set drive duty Ddr (step S450). In this case, the purge control valve 65 is closed.

Then, the valve passing purge flow rate Qpv is estimated based on the intake air amount Qa and the required purge rate Rprq (step S460), and this routine is terminated. Here, the valve passing purge flow rate Qpv is the flow rate of the evaporated fuel gas that has passed through the purge control valve 65 of the common passage 61. The valve passing purge flow rate Qpv can be obtained by applying the intake air amount Qa and the required purge rate Rprq to the valve passing purge flow rate estimation map. The valve passage purge flow rate estimation map is predetermined by experiment and analysis as the relationship between the intake air amount Qa and the required purge rate Rprq and the valve passage purge flow rate Qpv, and is stored in a ROM or flash memory (not shown). When the purge control valve 65 is closed, the value of the valve passing purge flow rate Qpv is 0.

When the purge condition flag Fpc is a value 1 in step S310, that is, when the purge condition is satisfied, the fully open purge flow rate Qpfo is estimated based on the surge pressure Ps and the value obtained by subtracting the intake pressure Pin from the boost pressure Pc. (Step S320). Here, the fully open purge flow rate Qpfo is a purge flow rate (volumetric flow rate of the evaporated fuel gas supplied to the intake pipe 23) when the drive duty of the purge control valve 65 is 100%. The fully open purge flow rate Qpfo can be obtained by applying the surge pressure Ps and the value obtained by subtracting the intake pressure Pin from the boost pressure Pc to the fully open purge flow rate estimation map. The map for estimating the fully open purge flow rate is predetermined by experiments and analysis as the relationship between the surge pressure Ps, the value obtained by subtracting the intake pressure Pin from the boost pressure Pc, and the fully open purge flow rate Qpfo, and is stored in a ROM or flash memory (not shown). ing. FIG. 10 is an explanatory diagram showing an example of a map for estimating the fully open purge flow rate. As shown in the figure, the fully open purge flow rate Qpfo increases as the surge pressure Ps decreases (the absolute value as a negative value increases), and increases as the value obtained by subtracting the intake pressure Pin from the boost pressure Pc increases. Is set to.

Subsequently, the combustion chamber air amount Qcc, which is the air amount in the combustion chamber 30, is estimated based on the intake air amount Qa and the valve passing purge flow rate (past Qpv) before the predetermined time T2 (step S322). Here, as the valve passage purge flow rate (past Qpv) before the predetermined time T2, the value estimated in the process of step S460 when this routine is executed before the predetermined time T2 is used. The predetermined time T2 is defined as the time required for the evaporated fuel gas that has passed through the purge control valve 65 of the common passage 61 to reach the combustion chamber 30, and is set to the supercharging area flag Fc, the rotation speed Ne of the engine 12, and the like. Based time may be used, or a fixed time may be used for simplicity. The combustion chamber air amount Qcc can be obtained by applying, for example, the intake air amount Qa and the past valve passage purge flow rate (past Qpv) to the combustion chamber air amount estimation map. The map for estimating the amount of combustion chamber air is predetermined by experiments and analysis as the relationship between the intake air amount Qa and the past valve passage purge flow rate (past Qpv) and the combustion chamber air amount Qcc, and is stored in a ROM or flash memory (not shown). Has been done.

When the fully open purge flow rate Qpfo and the combustion chamber air amount Qcc are estimated in this way, the fully open purge rate Rpfo is estimated based on the estimated fully open purge flow rate Qpfo and the combustion chamber air amount Qcc (step S324). Here, the fully open purge rate Rpfo can be calculated by dividing the fully open purge flow rate Qpfo by the amount of air in the combustion chamber Qcc.

Subsequently, the value of the supercharged area flag Fc is examined (step S330). When the supercharging area flag Fc has a value of 0, that is, when it is estimated to be in the naturally aspirated area, the value Rpst1 is set in the start purge rate Rpst (step S340), and the value Rprs1 is input to restart the purge. The rate Rprs is set (steps S341 and S342), the update amount ΔRp is set to the value ΔRp1 (step S344), and the target purge rate Rptg is set to the value Rptg1 (step S346). Here, constant values are used for the value Rpst1, the value ΔRp1, and the value Rptg1. As the value Rprs1, the value set by the sub-processing routine described later is input.

When the supercharged area flag Fc is set to a value of 1 in step S340, that is, when it is estimated to be a supercharged area, the start purge rate Rpst is set to a value Rpst2 smaller than the value Rpst1 (step S350), and the restart purge is resumed. The rate Rprs is set to a value Rprs2 smaller than the value Rprs1 (step S352), the update amount ΔRp is set to ΔRp2 smaller than the value ΔRp1 (step S354), and the target purge rate Rptg is set to a value Rptg2 smaller than the value Rptg1. (Step S356). Here, constant values are used for the value Rpst2, the value Rprs2, the value ΔRp2, and the value Rptg2.

When the start purge rate Rpst, the restart purge rate Rprs, the update amount ΔRp, and the target purge rate Rptg are set in steps S340 to S346 or steps S350 to S356 in this way, the start purge rate Rpst or the restart purge rate Rprs and the update amount ΔRp are fully opened. The provisional request purge rate Rprqtmmp as a provisional value of the request purge rate Rprq is set using the purge rate Rpfo and the target purge rate Rptg (step S370).

Here, the provisional request purge rate Rprqtp is the fully open purge rate Rpfo and the target purge rate during the initial period of establishment of the purge condition (the period from the start of the establishment of the purge condition to the interruption or the end) in each trip. Within the range below the minimum value of Rptg, the starting purge rate Rpst is set to gradually increase by rate processing using the update amount ΔRp. Specifically, the provisional request purge rate Rprqtpp is set to the start purge rate Rpst immediately after the start of establishment in the initial establishment period of the purge condition in each trip, and thereafter, the previous request purge rate (previous Rprq). And the update amount ΔRp, the fully open purge rate Rpfo, and the target purge rate Rptg are used to set the value calculated by the equation (1).

Rprqtmp = min (previous Rprq + ΔRp, min (Rpfo, Rptg)) (1)

In addition, the provisional request purge rate Rprqtmmp is the fully open purge rate Rpfo and the target purge during the second and subsequent establishment periods of the purge condition (the period from the restart of the purge condition to the interruption or termination) in each trip. Within the range below the minimum value of the rate Rptg, the restart purge rate Rprs is set to gradually increase by rate processing using the update amount ΔRp. Specifically, for the provisional request purge rate Rprqtp, the restart purge rate Rprs is set immediately after the start (restart) of establishment in the second and subsequent establishment periods of the purge conditions in each trip, and then the equation (1). The value calculated by is set.

When the establishment of the purge condition is interrupted, for example, when the accelerator is turned off while the vehicle on which the engine device 10 is mounted is running and the fuel of the engine 12 is cut (the operation control of the engine 12 is interrupted). Can be mentioned.

When the provisional request purge rate Rprqtmp is set in this way, it is determined whether or not the previous supercharging area flag (previous Fc) has a value of 1 (step S380), and the current supercharging area flag (this time Fc) has a value of 0. (Step S382). The processing of steps S380 and S382 is whether or not the supercharging area flag Fc has just switched from the value 1 to the value 0, that is, the estimation of the supercharging area is switched to the estimation of the naturally aspirated area. It is a process of determining whether or not it is immediately after.

When the previous supercharging area flag (previous Fc) has a value of 0 in step S380, or when the current supercharging area flag (this time Fc) has a value of 1 in step S382, the supercharging area flag Fc starts from the value 1. It is determined that it is not immediately after the value is switched to 0, the provisional request purge rate Rprqtmp is set to the request purge rate Rprq (step S390), and the set request purge rate Rprq is divided by the fully open purge rate Rpfo to drive the purge control valve 65. The duty Ddr is set (step S440), and the purge control valve 65 is controlled using the set drive duty Ddr (step S450). Then, by the process of step S460 described above, the valve passing purge flow rate Qpv is estimated, and this routine is terminated.

In the embodiment, as described above, when the purge is executed, the start purge rate Rpst, the restart purge rate Rprs, the update amount ΔRp, and the target purge rate Rptg are made smaller in the supercharged area than in the naturally aspirated area. As a result, the provisional required purge rate Rprqtp and thus the required purge rate Rprq are reduced. When performing purging, in the supercharging region, the path volume from the evaporated fuel gas to the combustion chamber 30 of the engine 12 is larger than in the naturally aspirated region, and the supercharging pressure Pc and the ejector of the ejector 69 are large. The front air-fuel ratio AF1 tends to become unstable due to fuel injection control due to reasons such as pressure fluctuations. In the embodiment, when the purge is executed, the front air-fuel ratio AF1 can be suppressed from becoming unstable in the supercharged region by reducing the required purge rate Rprq as compared with the naturally aspirated region. ..

When the previous supercharging area flag (previous Fc) has a value of 1 in step S380 and the current supercharging area flag (this time Fc) has a value of 0 in step S382, the supercharging area flag Fc starts from the value 1. It is determined that the value has just been switched to 0, and data such as the upstream purge execution counter storage value Cpupsr and the value Rprs1 are input (step S400). Here, the upstream purge execution counter storage value Cpupsr is a storage value related to the upstream purge execution counter Cpup, and the upstream purge execution counter Cpup is related to the time when the purge is being executed and the dominant purge is the upstream purge. It is a counter. As described above, the value Rprs1 is set to the restart purge rate Rprs when the supercharging area flag Fc has a value of 0. The values set by the sub-processing routines of FIGS. 11 and 12 are input to the upstream purge execution counter Cpup and the value Rprs1. Hereinafter, the description of the purge control routine of FIGS. 6 and 7 will be interrupted, and the subprocessing routines of FIGS. 11 and 12 will be described.

The sub-processing routines of FIGS. 11 and 12 are repeatedly executed by the electronic control unit 70. When this routine is executed, the electronic control unit 70 first inputs data such as the opening degree Opv of the purge control valve 65, the required purge rate Rprq, and the control purge flag Fpd (step S600). Here, a value detected by the purge control valve position sensor 65a is input to the opening degree Opv of the purge control valve 65. The value set by the purge control routines of FIGS. 6 and 7 is input to the requested purge rate Rprq. The dominant purge flag Fpd has a value of 0 when the dominant purge of the downstream purge and the upstream purge is the downstream purge (evaporated fuel gas predominantly flows into the first purge passage 62) when the purge is being executed. Is set, and the value 1 is set when the dominant purge is the upstream purge (evaporated fuel gas predominantly flows in the second purge passage 63). The value set by the dominant purge determination routine of FIG. 13 is input to the dominant purge flag Fpd. Hereinafter, the description of the sub-processing routine of FIGS. 11 and 12 will be interrupted, and the control purge determination routine of FIG. 13 will be described.

The control purge determination routine of FIG. 13 is repeatedly executed by the electronic control unit 70 while the purge is being executed. In the embodiment, the control purge flag Fpd is held when the purge is not executed (when the repeated execution of this routine is interrupted). When this routine is executed, the electronic control unit 70 first inputs data such as an intake pressure Pin, a boost pressure Pc, a surge pressure Ps, and a drive duty Ddr (step S700). Here, a value detected by the intake pressure sensor 23b is input to the intake pressure Pin. The value detected by the boost pressure sensor 23c is input to the boost pressure Pc. The value detected by the surge pressure sensor 27a is input to the surge pressure Ps. The drive duty Ddr is input to the value set by the purge control routines of FIGS. 6 and 7.

When the data is input in this way, the ejector pressure Pej is estimated based on the value obtained by subtracting the intake pressure Pin from the boost pressure Pc and the drive duty Ddr (step S710). Here, the ejector pressure Pej can be obtained by applying the value obtained by subtracting the intake pressure Pin from the boost pressure Pc and the drive duty Ddr to the ejector pressure setting map. The map for setting the ejector pressure is predetermined by experiment and analysis as the relationship between the value obtained by subtracting the intake pressure Pin from the boost pressure Pc and the drive duty Ddr and the ejector pressure Pej, and is stored in a ROM or flash memory (not shown). .. FIG. 14 is an explanatory diagram showing an example of an ejector pressure setting map. As shown in the figure, the ejector pressure Pej becomes larger as the drive duty Ddr is larger (the absolute value as a negative value becomes smaller), and the boost pressure Pc (the value obtained by subtracting the intake pressure Pin from the boost pressure Pc). ) Is set to be smaller (the absolute value as a negative value is larger).

Subsequently, based on the surge pressure Ps, an offset amount kd for offsetting the surge pressure Ps is set in order to correct the influence of the cross-sectional area of the second purge passage 63 on the cross-sectional area of the first purge passage 62 (step S720). ). Here, the offset amount kd can be obtained by applying the surge pressure Ps to the offset amount setting map. The offset amount setting map is predetermined by experiment or analysis as the relationship between the surge pressure Ps and the offset amount cd, and is stored in a ROM or flash memory (not shown). FIG. 15 is an explanatory diagram showing an example of an offset amount setting map when the cross-sectional area of the second purge passage 63 is smaller than the cross-sectional area of the first purge passage 62. As shown in the figure, the offset amount kd is set so that the larger the absolute value as a negative value of the surge pressure Ps, the larger the absolute value as a negative value. This is based on the fact that the larger the absolute value of the surge pressure Ps as a negative value, the greater the influence of the cross-sectional area of the second purge passage 63 on the cross-sectional area of the first purge passage 62. When the first purge passage 62 and the second purge passage 63 are composed of pipes, the cross-sectional area is proportional to the square of the pipe diameter, so that the second purge passage 63 with respect to the cross-sectional area of the first purge passage 62 The influence based on the cross-sectional area can be rephrased as the influence based on the pipe diameter of the second purge passage with respect to the pipe diameter of the first purge passage 62.

Then, the ejector pressure Pej and the value obtained by subtracting the offset amount kd from the surge pressure Ps are compared (step S730). Then, when it is determined that the ejector pressure Pej is equal to or greater than the value obtained by subtracting the offset amount kd from the surge pressure Ps (the absolute value as a negative value is less than or equal to), the evaporated fuel gas dominates the first purge passage 62. (The dominant purge is the downstream purge), the value 0 is set in the dominant purge flag Fpd (step S740), and this routine is terminated.

When it is determined in step S730 that the ejector pressure Pej is smaller than the value obtained by subtracting the offset amount kd from the surge pressure Ps (the absolute value as a negative value is large), the evaporated fuel gas dominates the second purge passage 63. It is determined that the flow (the dominant purge is the upstream purge), the value 1 is set in the dominant purge flag Fpd (step S750), and this routine is terminated.

The control purge determination routine of FIG. 13 has been described. The description returns to the subprocessing routines of FIGS. 11 and 12. When data is input in step S600, it is determined whether or not purging is executed using the opening degree Opv of the purge control valve 65 (step S610). When it is determined that the purge has not been executed, the purge non-execution counter Cnp is counted up by a value of 1 from the previous value (step S614). Here, the purge non-execution counter Cnp is a counter related to the purge non-execution time. The purge non-execution counter Cnp is set to a value of 0 as an initial value when the current trip is started.

When it is determined in step S610 that purging is being executed, the value of the dominant purge flag Fpd is checked (step S612). When the dominant purge flag Fpd is a value 0, that is, when the dominant purge is a downstream purge, the purge non-execution counter Cnp is counted down by a value of 1 from the previous value and further limited to a value of 0 (lower limit guard) and updated. (Step S616). When the dominant purge flag Fpd has a value of 1, that is, when the dominant purge is an upstream purge, the purge non-execution counter Cnp is held at the previous value (step S618).

Subsequently, it is determined whether or not the purge is being executed (step S620), and the value of the dominant purge flag Fpd is examined (step S622). When it is determined in step S620 that the purge is being executed and the control purge flag Fpd is a value 0 in step S622, that is, when the control purge is a downstream purge, the downstream purge integration counter Cpdn is counted up by a value of 1 from the previous value. And update (step S624). Here, the downstream purge integration counter Cpdn is a counter related to the integration time during which the purge is being executed in the current trip and the dominant purge is the downstream purge. The downstream purge integration counter Cpdn is set to a value of 0 as an initial value when the current trip is started. When it is determined in step S620 that the purge is not executed, or when the dominant purge flag Fpd is a value 1 in step S622, that is, when the dominant purge is an upstream purge, the downstream purge integration counter Cpdn is held at the previous value (step S626). ).

Further, the value of the dominant purge flag Fpd is examined (step S630). When the dominant purge flag Fpd is a value 1, that is, when the dominant purge is an upstream purge, it is determined whether or not the purge is executed using the opening degree Opv of the purge control valve 65 (step S632). When it is determined that purging is being executed, the upstream purge execution counter Cpup is counted up by a value of 1 from the previous value (step S634), and when it is determined that purging is not being executed, the upstream purge execution counter Cpup is incremented by the previous value. Hold in (step S636). Here, the upstream purge execution counter Cpup is, as described above, a counter related to the time during which the purge is being executed and the dominant purge is the upstream purge. The upstream purge execution counter Cpup is set to a value of 0 as an initial value when the current trip is started.

When the dominant purge flag Fpd has a value of 0 in step S630, that is, when the dominant purge is a downstream purge, it is determined whether or not the previous upstream purge execution counter (previous Cpup) has a positive value (step S637). When it is determined that the previous upstream purge execution counter (previous Cpup) has a positive value, the previous upstream purge execution counter (previous Cpup) is set to the upstream purge execution counter storage value Cpupsr (step S638), and the upstream purge execution is executed. The value 0 is set in the counter Cpup (step S639). When the previous upstream purge execution counter (previous Cpup) has a value of 0 in step S637, the value 0 is set in the upstream purge execution counter Cpup without executing the process of step S638 (step S639). Therefore, the upstream purge execution counter storage value Cpupsr is a value immediately before the upstream purge execution counter Cpup switches from a positive value to a value of 0. The upstream purge execution counter storage value Cpupsr corresponds to the purge execution time from immediately after the control purge flag Fpd is switched from the value 0 to the value 1 to immediately before the value is switched to the value 0.

FIG. 16 is an explanatory diagram showing an example of the presence / absence of purge execution, the control purge flag Fpd, the purge non-execution counter Cnp, the downstream purge integration counter Cpdn, and the upstream purge execution counter Cpup. First, the purge non-execution counter Cnp will be described. When the dominant purge flag Fpd has a value of 0 (~ time t21, time t22 ~), the purge non-execution counter Cnp is counted up when the purge is not executed, and the purge non-execution counter Cnp is counted when the purge is executed. Count down. Further, when the control purge flag Fpd has a value of 1 (time t21 to t22), the purge non-execution counter Cnp is counted up when the purge is not executed, and the purge non-execution counter Cnp is set when the purge is executed. Hold. The longer the non-execution time of purging (duration of closing the purge control valve 65), the higher the actual purge concentration on the fuel tank 11 side than that of the purge control valve 65. The discrepancy between the purge concentration-related value Cp to be performed and the ideal purge concentration-related value Cpt, which is the purge concentration-related value corresponding to the actual purge concentration, becomes large, and the reliability of the purge concentration-related value Cp becomes low. Therefore, it is assumed that the higher the purge non-execution counter Cnp, the lower the reliability of the purge concentration-related value Cp. Further, when the purge is being executed, when the dominant purge is the upstream purge, the path volume of the evaporated fuel gas to the combustion chamber 30 of the engine 12 is larger than that when the dominant purge is the downstream purge. Due to the large size and fluctuations in the boost pressure Pc and the ejector pressure of the ejector 69, the front air-fuel ratio AF1 tends to become unstable due to fuel injection control, and the reliability of the purge concentration-related value Cp becomes low. Cheap. Therefore, in the embodiment, when the dominant purge is the downstream purge, the purge unexecuted counter Cnp is counted down, whereas when the dominant purge is the upstream purge, the purge unexecuted counter is counted down. It was assumed that Cnp was retained.

Subsequently, the downstream purge integration counter Cpdn will be described. When the dominant purge flag Fpd has a value of 0 (~ time t21, time t22 ~), the downstream purge integration counter Cpdn is held when the purge is not executed, and the downstream purge integration counter Cpdn is held when the purge is executed. Count up. Further, when the dominant purge flag Fpd is a value 1 (time t21 to t22), the downstream purge integration counter Cpdn is held regardless of whether or not the purge is executed. In the current trip, the longer the integrated time of the downstream purge is, the larger the number of times the purge concentration-related value Cp is set (the number of learnings) in the downstream purge, and the higher the reliability of the purge concentration-related value Cp. Therefore, it is assumed that the larger the downstream purge integration counter Cpdn, the higher the reliability of the purge concentration related value Cp. As described above, when the dominant purge is the upstream purge, the reliability of the purge concentration-related value Cp tends to be lower than when the dominant purge is the downstream purge. .. Therefore, in the embodiment, when the dominant purge is the downstream purge, the downstream purge integration counter Cpdn is counted up, whereas when the dominant purge is the upstream purge, the downstream purge integration is performed. It was assumed that the counter Cpdn was held.

Further, the upstream purge execution counter Cpup will be described. When the dominant purge flag Fpd has a value of 0 (~ time t21, time t22 ~), the value 0 is set in the upstream purge execution counter Cpup regardless of whether or not the purge is executed. When the dominant purge flag Fpd has a value of 1 (time t21 to t22), the upstream purge execution counter Cpup is held when the purge is not executed, and the upstream purge execution counter Cpup is counted up when the purge is being executed. .. As described above, when the dominant purge is the upstream purge, the reliability of the purge concentration-related value Cp tends to be lower than when the dominant purge is the downstream purge. Therefore, it is assumed that the larger the upstream purge execution counter Cpup (upstream purge execution counter storage value Cpupsr), the lower the reliability of the purge concentration-related value Cp.

When the purge non-execution counter Cnp, the downstream purge integration counter Cpdn, and the upstream purge execution counter Cpup are set in this way, the upper limit guard value Rpgd1 is set based on the purge non-execution counter Cnp (step S640). Here, the upper limit guard value Rpgd1 can be obtained by applying the purge non-execution counter Cnp to the upper limit guard value setting map. The upper limit guard value setting map is predetermined as the relationship between the purge non-execution counter Cnp and the upper limit guard value Rpgd1, and is stored in a ROM or flash memory (not shown). FIG. 17 is an explanatory diagram showing an example of a map for setting an upper limit guard value. As shown in the figure, the upper limit guard value Rpgd1 is set so as to become smaller as the purge non-execution counter Cnp becomes larger.

Subsequently, it is determined whether or not the purge is being executed (step S650), and when it is determined that the purge is not being executed, the maximum purge rate storage value Rpmaxsr is held at the previous value (step S654). When it is determined in step S650 that purging is being executed, the value of the dominant purge flag Fpd is checked (step S652). When the dominant purge flag Fpd is a value 0, that is, when the dominant purge is a downstream purge, as shown in equation (2), the maximum value of the required purge rate Rprq and the previous maximum purge rate storage value (previous Rpmaxsr). Is limited by the upper limit guard value Rpgd1 (upper limit guard) to set the maximum purge rate storage value Rpmaxsr (step S656), and the set maximum purge rate storage value Rpmaxsr is set to the upper limit guard value Rpgd2 (step S657). Here, the maximum purge rate storage value Rpmaxsr when the control purge flag Fpd is a value 0 is a storage value related to the maximum value of the required purge rate Rprq when the control purge flag Fpd is a value 0 in the current trip.

Rpmaxsr = min (max (Rprq, previous Rpmaxsr), Rpgd1) (2)

When the dominant purge flag Fpd is a value 1 in step S652, that is, when the dominant purge is an upstream purge, as shown in the equation (3), of the requested purge rate Rprq and the previous maximum purge rate storage value (previous Rpmaxsr). The maximum value of is limited by the upper limit guard values Rpgd1 and Rpgd2 (upper limit guard), and the maximum purge rate storage value Rpmaxsr is set (step S658). Here, the maximum purge rate storage value Rpmaxsr when the dominant purge flag Fpd is a value 1 is the maximum value of the requested purge rate Rprq when the dominant purge flag Fpd is a value 1 in the current trip, and the dominant purge flag Fpd is a value 0. It is a storage value related to a value obtained by limiting (upper limit guard) by the maximum value (upper limit guard value Rpgd2) of the required purge rate Rprq at that time. In the embodiment, in this way, the maximum purge rate storage value Rpmaxsr when the dominant purge flag Fpd is a value 1 is set so as not to exceed the maximum purge rate storage value Rpmaxsr when the dominant purge flag Fpd is a value 0. did.

Rprssr = min (max (Rprq, previous Rpmaxsr), Rpgd1, Rpgd2) (3)

Subsequently, it is determined whether or not the purge is being executed (step S660), and the value of the dominant purge flag Fpd is examined (step S662). When it is determined in step S660 that the purge is not executed, or when the dominant purge flag Fpd is a value 1 in step S662, that is, when the dominant purge is an upstream purge, the storage value Rprssr for the restart purge rate is held at the previous value ( Step S664). When it is determined in step S660 that the purge is being executed, and when the control purge flag Fpd has a value of 0 in step S662, that is, when the control purge is a downstream purge, as shown in the equation (4), the request purge rate Rprq and The maximum value of the maximum purge rate storage value Rpmaxsr is limited by the upper limit guard value Rpgd1 (upper limit guard), and the storage value Rprssr for the restart purge rate is set (step S666). Here, the storage value Rprssr for the restart purge rate is a storage value used to set the above-mentioned value Rprs1 (restart purge rate Rprs when the supercharging area flag Fc is a value 0).

Rprssr = min (max (Rprq, Rpmaxsr), Rpgd1) (4)

When the storage value Rprssr for the restart purge rate is set in this way, the value Rprs1 (restart purge rate Rprs when the supercharging area flag Fc is 0) is based on the set storage value Rprssr for the restart purge rate and the downstream purge integration counter Cpdn. Is set (step S670), and this routine is terminated. Here, the value Rprs1 can be set, for example, by multiplying the storage value Rprssr for the restart purge rate by the reflection coefficient kpdn based on the downstream purge integration counter Cpdn. The reflection coefficient kpdn can be obtained by applying the downstream purge integration counter Cpdn to the reflection coefficient setting map. The reflection coefficient setting map is predetermined as the relationship between the downstream purge integration counter Cpdn and the reflection coefficient kpdn, and is stored in a ROM or flash memory (not shown). FIG. 18 is an explanatory diagram showing an example of a map for setting a reflection coefficient. As shown in the figure, the reflection coefficient kpdn is set so that the larger the downstream purge integration counter Cpdn is, the larger the value is within the range of 0 or more and 1 or less.

Therefore, the value Rprs1 (restart purge rate Rprs when the supercharging area flag Fc is a value 0) becomes larger as the downstream purge integration counter Cpdn is larger in the range below the storage value Rprssr for the restart purge rate. As described above, it is assumed that the larger the downstream purge integration counter Cpdn, the higher the reliability of the purge concentration related value Cp. Therefore, when the downstream purge integration counter Cpdn is relatively large, the purge can be restarted at a relatively large purge rate by relatively increasing the restart purge rate Rprs1. Further, in the embodiment, the larger the purge non-execution counter Cnp, the smaller the upper limit guard value Rpgd1, so that the maximum purge rate storage value Rpmaxsr and the restart purge rate storage value Rprssr tend to be small, and the value Rprs1 tends to be small. As described above, it is assumed that the higher the purge non-execution counter Cnp, the lower the reliability of the purge concentration-related value Cp. Therefore, when the purge non-execution counter Cnp is relatively large, the purge is restarted at a relatively large purge rate. Then, the front air-fuel ratio AF1 tends to become unstable. On the other hand, as the purge non-execution counter Cnp is larger, the upper limit guard value Rpgd1 is made smaller, the maximum purge rate storage value Rpmaxsr and the restart purge rate storage value Rprssr are more likely to be smaller, and the value Rprs1 is more likely to be smaller. This makes it possible to prevent the front air-fuel ratio AF1 from becoming unstable when the purge is restarted.

The sub-processing routines of FIGS. 11 and 12 have been described. Returning to the description of the purge control routine of FIGS. 6 and 7. When the upstream purge execution counter storage value Cpupsr and the restart purge rate Rprs1 are input in step S400, the provisional lower limit purge rate Rpmintmp is set as a temporary value of the lower limit purge rate Rpmin based on the upstream purge execution counter storage value Cpupsr (step S410). , The minimum value of the set provisional lower limit purge rate Rpminmp and the value Rprs1 is set to the lower limit purge rate Rpmin (step S420).

Here, the provisional lower limit purge rate Rpmintmp can be obtained by applying the upstream purge execution counter storage value Cpupsr to the temporary lower limit purge rate setting map. The temporary lower limit purge rate setting map is predetermined as the relationship between the upstream purge execution counter storage value Cpupsr and the temporary lower limit purge rate Rpmintmp, and is stored in a ROM or flash memory (not shown). FIG. 19 is an explanatory diagram showing an example of a map for setting a temporary lower limit purge rate. As shown in the figure, the provisional lower limit purge rate Rpmintp is set so as to become smaller as the upstream purge execution counter storage value Cpupsr becomes larger.

Then, the provisional request purge rate Rprqtpm set in step S370 is limited by the lower limit purge rate Rpmin (lower limit guard), and the request purge rate Rprq is set (step S430). Then, by the processing of steps S440 and S450 described above, the required purge rate Rprq is divided by the fully open purge rate Rpfo to set the drive duty Ddr of the purge control valve 65 to control the purge control valve 65, and the purge control valve 65 is controlled. By the process, the valve passing purge flow rate Qpv is estimated, and this routine is terminated.

Immediately after the supercharging area flag Fc is switched from the value 1 to the value 0 (the estimation of the supercharging area is switched to the estimation of the naturally aspirated area) by such processing, the provisional request purge rate Rprqtpm is smaller than the lower limit purge rate Rpmin. Occasionally, the required purge rate Rprq will be raised to the lower limit purge rate Rpmin. As a result, the required purge rate Rprq (actual purge rate) can be increased in a shorter time after switching from the estimation of the supercharged area to the estimation of the naturally aspirated area.

By the way, immediately after the supercharging area flag Fc is switched from the value 1 to the value 0, the larger the upstream purge execution counter storage value Cpupsr is, the longer the upstream purge time is, and when the required purge rate Rprq is raised, the front air-fuel ratio is increased. It is assumed that AF1 tends to be unstable. Therefore, in the embodiment, immediately after the supercharging area flag Fc is switched from the value 1 to the value 0, the provisional lower limit purge rate Rpmintp is set so that the larger the upstream purge execution counter storage value Cpupsr is, the smaller the provisional lower limit purge rate Rpmintmp is set. The required purge rate Rprq was set using the lower limit purge rate Rpmin based on the purge rate Rpmintp. As a result, when the upstream purge is executed for a relatively long time and then switched to the downstream purge, the increase in the required purge rate Rprq is relatively small, and the front air-fuel ratio AF1 is suppressed from becoming unstable. Can be done.

FIG. 20 is an explanatory diagram showing an example of the state of the surge pressure Ps, the supercharging area flag Fc, the required purge rate Rprq, and the storage value Rprssr for the restart purge rate. As shown in the figure, when the supercharging area flag Fc is a value 0 and the required purge rate Rprq is larger than the value Rptg2 (target purge rate Rptg when the supercharging area flag Fc is a value 1), the surge pressure Ps is the threshold Psref. When the above is reached (time t41), the supercharging area flag Fc is switched from the value 0 to the value 1, and the required purge rate Rprq is limited to the value Rptg2. At this time, the storage value Rprssr for the restart purge rate is retained. After that, when the predetermined time T1 elapses after the surge pressure Ps reaches the threshold value Psref or less (time t42), the supercharging area flag Fc is switched from the value 1 to the value 0. In the comparative example, as shown by the alternate long and short dash line in FIG. 20, the required purge rate Rprq is then gradually increased from the value Rptg2 using the update amount ΔRp. On the other hand, in the embodiment, as shown by the solid line in FIG. 20, the required purge rate Rprq is raised by using the lower limit purge rate Rpmin based on the value Rprs1 based on the storage value Rprssr for the restart purge rate, and then the update amount. Gradually increase using ΔRp. Thereby, after the supercharging area flag Fc is switched from the value 1 to the value 0, the required purge rate Rprq can be increased in a shorter time.

In the engine device 10 of the embodiment described above, the required purge rate Rprq is the lower limit immediately after the supercharging area flag Fc is switched from the value 1 to the value 0 (the estimation of the supercharging area is switched to the estimation of the naturally aspirated area). When it is smaller than the purge rate Rpmin, the required purge rate Rprq is raised to the lower limit purge rate Rpmin. As a result, the required purge rate Rprq (actual purge rate) can be increased in a shorter time after switching from the estimation of the supercharged area to the estimation of the naturally aspirated area.

In the engine device 10 of the embodiment, in the purge control routine of FIGS. 6 and 7, immediately after the supercharging area flag Fc is switched from the value 1 to the value 0, the provisional lower limit purge rate Rpmintmp based on the upstream purge execution counter Cpup is set. The minimum value of the value Rprs1 (restart purge rate Rprs when the supercharging area flag Fc is 0) is set to the lower limit purge rate Rpmin, and the provisional request purge rate Rprqtmp is limited by the lower limit purge rate Rpmin (lower limit guard). The required purge rate Rprq was set. However, the provisional lower limit purge rate Rpmintmp based on the upstream purge execution counter Cpup may be set to the lower limit purge rate Rpmin without considering the value Rprs1. Further, the value Rprs1 may be set to the lower limit purge rate Rpmin without considering the upstream purge execution counter Cpup.

In the engine device 10 of the embodiment, in the purge control routine of FIGS. 6 and 7, immediately after the supercharging area flag Fc is switched from the value 1 to the value 0, the provisional request purge rate Rprqtmp is limited by the lower limit purge rate Rpmin ( The lower limit guard) was used to set the required purge rate Rprq. However, immediately after the supercharging area flag Fc is switched from the value 1 to the value 0, a value obtained by adding the raised amount ΔRprq to the provisional request purge rate Rprqtp may be set in the request purge rate Rprq. Here, the raising amount ΔRprq may be set so as to be smaller as the upstream purge execution counter Cpup is larger, or may be set to be larger as the value Rprs1 is larger, or a constant value may be set. It may be used.

In the engine apparatus 10 of the embodiment, in the subprocessing routines of FIGS. 11 and 12, based on the dominant purge flag Fpd, the purge non-execution counter Cnp, the downstream purge integration counter Cpdn, the upstream purge execution counter Cpup, and the maximum purge rate storage value Rpmaxsr , The storage value Rprssr for the restart purge rate was set. However, instead of the dominant purge flag Fpd, based on the upstream purge estimation flag Fpup, the purge unexecuted counter Cnp, the downstream purge integration counter Cpdn, the upstream purge execution counter Cpup, the maximum purge rate storage value Rpmaxsr, and the restart purge rate storage value Rprssr. May be set.

In the engine device 10 of the embodiment, in the sub-processing routines of FIGS. 11 and 12, the maximum purge rate storage value Rpmaxsr and the restart purge rate storage value Rprssr are set using the upper limit guard value Rpgd1 based on the purge non-execution counter Cnp. I made it. However, the maximum purge rate storage value Rpmaxsr and the restart purge rate storage value Rprssr may be set without using the upper limit guard value Rpgd1.

In the engine device 10 of the embodiment, the engine 12 is provided with an in-cylinder injection valve 28 for injecting fuel into the combustion chamber 30. However, the engine 12 may include, in addition to or in place of the in-cylinder injection valve 28, a port injection valve that injects fuel into the intake port.

In the engine device 10 of the embodiment, the supercharger 40 is configured as a turbocharger in which a compressor 41 arranged in the intake pipe 23 and a turbine 42 arranged in the exhaust pipe 35 are connected via a rotating shaft 43. I made it. However, instead of this, the compressor driven by the engine 12 or the motor may be configured as a supercharger arranged in the intake pipe 23.

In the engine device 10 of the embodiment, in the evaporative fuel processing device 50, the common passage 61 is connected to the vicinity of the canister 56 of the introduction passage 52. However, it may be connected to the canister 56.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the engine 12 corresponds to the "engine", the supercharger 40 corresponds to the "supercharger", the evaporative fuel processing device 50 corresponds to the "evaporated fuel processing device", and the electronic control unit 70 corresponds to the "evaporative fuel processing device". Corresponds to "control device".

As for the correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem, the invention described in the column of means for solving the problems of the examples is carried out. Since it is an example for specifically explaining the form for solving the problem, the elements of the invention described in the column of means for solving the problem are not limited. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to the embodiments, the present invention is not limited to these examples, and the present invention is not limited to these embodiments, and various embodiments are used without departing from the gist of the present invention. Of course it can be done.

The present invention can be used in the manufacturing industry of engine devices and the like.

10 engine device, 11 fuel tank, 11a internal pressure sensor, 12 engine, 14 crank shaft, 14a crank position sensor, 16 water temperature sensor, 17 low pressure side fuel passage, 18 high pressure side pump, 19 high pressure side fuel passage, 22 air cleaner, 23 intake pipe , 23a air flow meter, 23b intake pressure sensor, 23c boost pressure sensor, 24 bypass pipe, 25 intercooler, 26 throttle valve, 26a throttle position sensor, 27 surge tank, 27a surge pressure sensor, 27b temperature sensor, 28 in-cylinder injection Valve, 28a fuel pressure sensor, 29 intake valve, 30 combustion chamber, 31 ignition plug, 32 piston, 34 exhaust valve, 35 exhaust pipe, 35a front air fuel ratio sensor, 35b rear air fuel ratio sensor, 36 bypass pipe, 37, 38 purification device , 40 supercharger, 41 compressor, 42 turbine, 43 rotary shaft, 44 waste gate valve, 45 blow-off valve, 50 evaporative fuel processing device, 52 introduction passage, 53 open / close valve, 54 bypass passage, 54a, 54b branch, 55a , 55b relief valve, 55b relief valve, 56 canister, 57 open air passage, 58 air filter, 61 common passage, 61a branch point, 62 first purge passage, 63 second purge passage, 63a OBD sensor, 64 buffer section, 65 purge control valve, 65a purge control valve position sensor, 66 check valve, 67 check valve, 68 return passage, 69 ejector, 70 electronic control unit.

Claims (1)

An engine that has a throttle valve located in the intake pipe and outputs power using fuel supplied from the fuel tank.
A turbocharger having a compressor arranged on the upstream side of the throttle valve of the intake pipe, and
Evaporated fuel gas containing evaporative fuel generated in the fuel tank is branched into a first purge passage and a second purge passage connected to the downstream side of the throttle valve of the intake pipe and supplied to the intake pipe. An intake port is connected to a supply passage and a recirculation passage from between the compressor of the intake pipe and the throttle valve, and an exhaust port is connected to the upstream side of the compressor of the intake pipe and the second purge passage. An evaporative fuel treatment device having an ejector to which a suction port is connected and a purge control valve provided in the supply passage.
A control device that controls the purge control valve based on a required purge rate that slowly changes toward the target purge rate when performing a purge that supplies the evaporated fuel gas to the intake pipe.
It is an engine device equipped with
When executing the purge, the control device sets the required purge rate so as to be smaller than the naturally aspirated region in the supercharged region, and further switches from the supercharged region to the naturally aspirated region. When this happens, the required purge rate is increased.
Engine equipment.

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