JP2021181771A - Engine equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both suppression of deposit adhesion to a fuel injection valve and suppression of generation of engine rich engine stall. SOLUTION: When the purge is interrupted and then restarted including the second purge of supplying the evaporated fuel gas to the intake pipe through the second purge passage, it is possible to suppress the deposit from adhering to the fuel injection valve. The first permissible limit rate of the purge rate, the evaporated fuel gas remaining in the second purge passage, and the evaporated fuel gas newly supplied to the first purge passage merge on the downstream side of the throttle valve of the intake pipe. The minimum as an absolute value of the second permissible limit rate of the purge rate of the first purge that supplies the evaporated fuel gas to the intake pipe through the first purge passage, which can suppress the rich entanglement of the engine at the time of Set the upper limit purge rate based on the value. [Selection diagram] FIG. 16

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 supercharging pressure from the supercharger are used to be negative. It has been proposed to provide a second purge passage for purging the evaporated fuel gas upstream of the compressor of the turbocharger in the intake pipe by an ejector for generating pressure (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 passage in which the purge is performed is switched between the first purge passage and the second purge passage, the control characteristic data used for controlling the purge control valve is combined with the first control characteristic data suitable for the first purge passage. Switch with the second control characteristic data suitable for the second purge passage.

Further, as an engine device of this type, it is also proposed to have a purge pipe for supplying a purge gas containing evaporative fuel generated in the fuel tank to the intake pipe of the engine and a purge control valve provided in the purge pipe. (See, for example, Patent Document 2). In this engine device, the amount of fuel contained in the purge gas is reduced and corrected from the injection amount injected from the fuel injection device arranged in the combustion chamber. In addition, the tip temperature (nozzle temperature) of the fuel injection device is estimated, and the deposit increase temperature at which the deposit accumulated at the tip of the fuel injection device increases is set according to the fuel pressure, based on the nozzle temperature and the deposit increase temperature. , Set the upper limit of the supply amount of purge gas to be supplied to the intake pipe. In this way, the accumulation of deposits on the nozzle is suppressed.

Japanese Unexamined Patent Publication No. 2019-052561 Japanese Unexamined Patent Publication No. 2012-21455

How to apply to a hardware configuration such as Patent Document 1 when a process of setting an upper limit of a purge gas supply amount based on a nozzle temperature and a deposit increase temperature is applied as in Patent Document 2. It is an issue. Further, in the case of a hard configuration as in Patent Document 1, when the purge is carried out by the second purge passage, the purge gas is on the downstream side of the throttle valve of the intake pipe as compared with the case where the purge is carried out by the first purge passage. It takes a long time to reach. Therefore, when the detection that the purge is carried out by the second purge passage leads to the detection that the purge is carried out by the first purge passage, the purge gas remaining in the second purge passage is used for a while. It is assumed that the purge gas newly supplied to the first purge passage merges on the downstream side of the throttle valve of the intake pipe and is sucked into the combustion chamber. If a large amount of purge gas (evaporated fuel) is sucked into the combustion chamber at this time, a rich engine stall may occur.

The main object of the engine device of the present invention is to suppress the adhesion of deposits to the fuel injection valve and the generation of rich engine stalls at the same time.

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 is
An engine that has a throttle valve arranged in an intake pipe and a fuel injection valve and outputs power using fuel supplied from a 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.
When executing a purge for supplying the evaporated fuel gas to the intake pipe, a control device that controls the purge control valve by setting a required purge rate within the range of the upper limit purge rate or less.
It is an engine device equipped with
When the control device interrupts the purge and then restarts the purge including a second purge that supplies the evaporated fuel gas to the intake pipe through the second purge passage, a deposit is made on the fuel injection valve. The first permissible limit rate of the purge rate capable of suppressing the adhesion of the gas, the evaporated fuel gas remaining in the second purge passage, and the evaporated fuel gas newly supplied to the first purge passage are the intakes. The purge rate of the first purge that supplies the evaporated fuel gas to the intake pipe through the first purge passage, which can suppress the rich entanglement of the engine when merging on the downstream side of the throttle valve of the pipe. The upper limit purge rate is set based on the second allowable limit rate and the minimum value as an absolute value.
The gist is that.

In the engine device of the present invention, when the purging for supplying the evaporated fuel gas to the intake pipe is executed, the required purge rate is set within the range of the upper limit purge rate or less to control the purge control valve. In this case, when the purge is interrupted and then restarted including the second purge in which the evaporated fuel gas is supplied to the intake pipe through the second purge passage, it is possible to suppress the deposit from adhering to the fuel injection valve. The first permissible limit rate of the purge rate, the evaporated fuel gas remaining in the second purge passage, and the evaporated fuel gas newly supplied to the first purge passage merge on the downstream side of the throttle valve of the intake pipe. The minimum as an absolute value of the second permissible limit rate of the purge rate of the first purge that supplies the evaporated fuel gas to the intake pipe through the first purge passage, which can suppress the rich entanglement of the engine at the time of Set the upper limit purge rate based on the value. As a result, it is possible to suppress the adhesion of the deposit to the fuel injection valve and the generation of rich engine stall at the same time.

In the engine device of the present invention, the control device estimates that the purge does not include the second purge when the throttle post-throttle pressure, which is the pressure downstream of the throttle valve of the intake pipe, is less than the threshold value. When the throttle post-pressure is equal to or higher than the threshold, a predetermined time elapses when the throttle post-pressure reaches from the threshold or higher to less than the threshold in the estimation process of presuming that the purge includes the second purge. The estimation continues until the purge includes the second purge, and further, when the control device estimates that the purge includes the second purge when the purge is restarted, the first purge is performed. The upper limit purge rate may be set based on the 1 permissible limit rate and the 2nd permissible limit rate.

In this case, the control device, when executing the purge, has a boost pressure which is a pressure between the compressor of the intake pipe and the throttle valve and a pressure on the upstream side of the compressor of the intake pipe. Based on the pressure difference from the front pressure of a certain compressor and the drive duty of the purge control valve, the relative pressure of the ejector, which is the pressure of the suction port of the ejector, is estimated, and the relative pressure of the ejector and the rear pressure of the throttle are calculated. Based on this, the dominant purge among the first purge and the second purge is determined, and when the second purge is the dominant purge, the upper limit purge rate is set based on the first allowable limit rate. However, when it is estimated that the first purge is the dominant purge and the purge includes the second purge, the upper limit purge rate may be set based on the second allowable limit rate.

In this case, the control device is based on the relative pressure of the ejector and the value obtained by adding the offset amount based on the cross-sectional area of the second purge passage to the cross-sectional area of the first purge passage to the throttle rear pressure. It may be used to determine the control purge. In this way, the dominant purge can be determined more appropriately as compared with the case where the offset amount based on the cross-sectional area of the second purge passage with respect to the cross-sectional area of the first purge passage is not taken into consideration. Here, the "cross-sectional area" may be represented by the pipe diameter.

In this case, the control device may set the offset amount so that the larger the absolute value as the negative value of the throttle rear pressure, the larger the absolute value as the negative value. This is based on the fact that the larger the absolute value as the negative value of the throttle rear pressure, the greater the influence of the cross-sectional area of the second purge passage on the cross-sectional area of the first purge passage.

It is a block diagram which shows the outline of the structure of the engine device 10 of this invention. 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 explanatory drawing which shows an example of a plurality of load factor regions Rk [1] to Rk [n]. It is a flowchart which shows an example of the air-fuel ratio correction amount setting routine. It is explanatory drawing which shows an example of the map for setting the air-fuel ratio correction amount. It is explanatory drawing which shows an example of the purge correction amount setting routine. It is explanatory drawing which shows an example of the map for setting the update amount. It is a flowchart which shows an example of a purge control routine. It is a flowchart which shows an example of the control purge determination routine. It is a flowchart which shows an example of the upstream purge estimation routine. It is explanatory drawing which shows an example of the map for setting the relative pressure of an ejector. 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 surge pressure Ps and the upstream purge estimation flag Fpup. It is explanatory drawing which shows an example of the map for full-open purge flow rate estimation. It is a flowchart which shows an example of the upper limit purge rate setting routine. It is explanatory drawing which shows an example of the map for protection of an in-cylinder injection valve.

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 or various hybrid vehicles, and as shown in FIGS. 1 and 2, an engine 12, a supercharger 40, an evaporative fuel processing device 50, and electronic control are provided. It includes a 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 evaporated 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 is generated, and a 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 decompressed 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, and the intake pressure from the intake pressure sensor 23b installed on the upstream side of the compressor 41 of the intake pipe 23 (before the compressor). Pressure) Pin, the boost pressure Pc from the boost pressure sensor 23c attached between the compressor 41 of the intake pipe 23 and the intercooler 25 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.

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, the air-fuel ratio correction amount α [i], 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 air-fuel ratio correction amount α [i] belongs to the region (region) to which the current load factor KL belongs among the plurality of load factor regions Rk [1] to Rk [n] (n: number of regions) classified for the load factor KL. It is a correction amount related to the deviation (offset amount) of the front air-fuel ratio sensor 35a of the number i (i: any one of 1)), and the value set by the air-fuel ratio correction amount setting routine described later is input. Will be done. FIG. 4 is an explanatory diagram showing an example of a plurality of load factor regions Rk [1] to Rk [n]. In the plurality of load factor regions Rk [1] to Rk [n], as shown in the illustration, the range assumed for the load factor KL is the load factor region Rk [1] in order from the side with the smallest load factor KL. , ..., Rk [n] and the area width (range of load factor KL) of the load factor region Rk [n] having the highest load factor is the other load factor regions Rk [1] to Rk [n-1]. ] It is assumed that it is divided and set so as to be wider than the area width. 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), and the air-fuel ratio correction amount α [i] and the purge correction amount β are added to the set base injection amount Qfbs. The required injection amount Qf * of the in-cylinder injection valve 28 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, regarding the process of setting the air-fuel ratio correction amounts α [1] to α [n] of the plurality of load factor regions Rk [1] to Rk [n] used in the fuel injection amount control routine of FIG. , The air-fuel ratio correction amount setting routine of FIG. 5 will be described. This routine is repeatedly executed by the electronic control unit 70. The air-fuel ratio correction amounts α [1] to α [n] in the load factor regions Rk [1] to Rk [n] are the initial values or the last trips before the previous time until they are set in the current trip. It is the value set to.

When the air-fuel ratio correction amount setting routine of FIG. 5 is executed, the electronic control unit 70 first determines whether or not this routine is executed for the first time in the current trip (step S200). Then, when it is determined that this routine is executed for the first time in the current trip, all of the setting completion flags Fα [1] to Fα [n] of the plurality of load factor regions Rk [1] to Rk [n] are set. The value is reset to 0 as the initial value (step S210). Here, the setting completion flags Fα [1] to Fα [n] are flags indicating whether or not the air-fuel ratio correction amounts α [1] to α [n] are set in the current trip, respectively. When it is determined in step S200 that this routine is not executed for the first time in the current trip, the process of step S210 is not executed.

Subsequently, data such as the cooling water temperature Tw of the engine 12, the steady operation flag Fst, and the area number i of the area to which the current load factor KL belongs among the plurality of load factor areas Rk [1] to Rk [n] are input. (Step S220). Here, a value detected by the water temperature sensor 16 is input as the cooling water temperature Tw. For the steady operation flag Fst, a value set by a steady operation flag setting routine (not shown) is input. In the steady operation flag setting routine, the electronic control unit 70 determines whether or not the engine 12 is in steady operation using at least one of the engine 12 rotation speed Ne, the intake air amount Qa, and the load factor KL. When it is determined that the engine 12 is in steady operation, the value 1 is set in the steady operation flag Fst, and when it is determined that the engine 12 is not in steady operation, the value 0 is set in the steady operation flag Fst. As the area number i of the belonging area, a value set based on the load factor KL and a plurality of load factor areas Rk [1] to Rk [n] is input.

Then, the cooling water temperature Tw is compared with the threshold value Twref (step S230), and the value of the steady operation flag Fst is examined (step S240). Here, as the threshold value Twref, for example, about 55 ° C. to 65 ° C. is used. The process of steps S230 and S240 is a process of determining whether or not the setting condition of the air-fuel ratio correction amount α [i] of the area number i is satisfied. When the cooling water temperature Tw is less than the threshold value Twref in step S230, or when the steady operation flag Fst is a value 0 in step S240, it is determined that the setting condition of the air-fuel ratio correction amount α [i] of the area number i is not satisfied. , End this routine.

When the cooling water temperature Tw is equal to or higher than the threshold value Twref in step S230 and the steady operation flag Fst is a value 1 in step S240, it is determined that the setting condition of the air-fuel ratio correction amount α [i] of the region number i is satisfied, and the region is determined. Check the value of the setting completion flag Fα [i] of the number i (step S250). Then, when the setting completion flag Fα [i] of the area number i is a value 0, it is determined that the air-fuel ratio correction amount α [i] of the area number i is not set in the current trip, and the front air-fuel ratio AF1 is input. (Step S260), the air-fuel ratio correction amount α [i] of the area number i is set based on the input front air-fuel ratio AF1 (step S270), and the value 1 is set to the setting completion flag Fα [i] of the area number i. It is set (step S280), and this routine is terminated.

Here, a value detected by the front air-fuel ratio sensor 35a is input to the front air-fuel ratio AF1. The air-fuel ratio correction amount α [i] of the area number i can be obtained by applying the front air-fuel ratio AF1 when the setting condition is satisfied to the air-fuel ratio correction amount setting map. The map for setting the air-fuel ratio is based on experiments and analysis as the relationship between the front air-fuel ratio AF1 and the air-fuel ratio correction amount α [i] when the setting condition of the air-fuel ratio correction amount α [i] of the area number i is satisfied. It is predetermined and stored in a ROM or flash memory (not shown). FIG. 6 is an explanatory diagram showing an example of a map for setting an air-fuel ratio correction amount. As shown in the figure, the air-fuel ratio correction amount α [i] is within the negative range and positive when the front air-fuel ratio AF1 is on the rich side and lean side with respect to the required air-fuel ratio AF * when the setting condition is satisfied. The absolute value is set so as to be within the range of and the larger the difference between the front air-fuel ratio AF1 and the required air-fuel ratio AF * (the front air-fuel ratio AF1 is separated from the required air-fuel ratio AF *). The smaller the air-fuel ratio correction amount α [i] 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. As described above, in the plurality of load factor regions Rk [1] to Rk [n], the region width of the load factor region Rk [n] having the highest load factor is other than the load factor regions Rk [1] to Rk [1]. Since it is set to be wider than the region width of Rk [n-1] (see FIG. 4), the reliability of the air-fuel ratio correction amount α [n] in the load factor region Rk [n] is the load factor. It is low compared to the reliability of the air-fuel ratio correction amounts α [1] to α [n-1] in the regions Rk [1] to Rk [n-1].

When the setting completion flag Fα1 [i] of the area number i is set to a value 1 in step S250, it is determined that the air-fuel ratio correction amount α [i] of the area number i is set in the current trip, and it is determined in steps S260 to S280. This routine is terminated without executing the process.

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. 7. This routine is repeatedly executed by the electronic control unit 70. When this routine is executed, the electronic control unit 70 first inputs the opening degree Opv of the purge control valve 65 (step S300), and executes the purge using the input opening degree Opv of the purge control valve 65. The presence or absence is determined (step S310). 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.

When it is determined in step S310 that the purge is not executed, the purge concentration-related value Cp is held (step S320), the purge correction amount β is set to a value 0 (step S330), 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 trip is started. 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 S310 that purging is being executed, data such as the intake air amount Qa, the front air-fuel ratio AF1, and the required purge rate Rprq are input (step S340). 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 set by the purge control routine described later is input to the requested purge rate Rprq. The required purge rate Rprq is set to a value of 0 when the purge condition described later is not satisfied.

Subsequently, the update amount ΔCp of the purge concentration-related value Cp is set based on the front air-fuel ratio AF1 (step S350), and the value obtained by adding the update amount ΔCp to the previous purge concentration-related value (previous Cp) is the purge concentration-related value. Set to Cp (step S360). 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. 8 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 S370), 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, and the intake air amount Qa and the required purge rate. 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. FIG. 9 is a flowchart showing an example of the purge control routine. FIG. 10 is a flowchart showing an example of a dominant purge determination routine for determining a dominant purge among a downstream purge and an upstream purge. FIG. 11 is a flowchart showing an example of an upstream purge estimation routine for estimating whether or not the purge includes an upstream purge (whether it is only a downstream purge). Here, the fact that the purge includes an upstream purge means that at least a part of the evaporated fuel gas supplied to the combustion chamber 30 is the evaporated fuel gas supplied through the second purge passage 63.

The purge control routine of FIG. 9 and the upstream purge estimation routine of FIG. 11 are repeatedly executed by the electronic control unit 70. The dominant purge determination routine of FIG. 10 is repeated when purging is being executed by the electronic control unit 70 (when the required duty Drq is set and the purge control valve 65 is controlled by the purge control routine of FIG. 9). Will be executed. Hereinafter, for the sake of simplicity, the determination of the dominant purge will be described using the dominant purge determination routine of FIG. 10, and the estimation of whether or not the purge includes the upstream purge (whether it is only the downstream purge) will be described in FIG. The upstream purge estimation routine will be described, and the purge control based on these determinations and estimates will be described using the purge control routine of FIG.

When the control purge determination routine of FIG. 10 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 required duty Drq (step S500). 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 required duty Drq is input to the value set by the purge control routine of FIG.

When the data is input in this way, the ejector relative pressure Pej is estimated based on the value obtained by subtracting the intake pressure Pin from the boost pressure Pc and the required duty Drq (step S510). Here, the ejector relative pressure Pej can be obtained by applying the value obtained by subtracting the intake pressure Pin from the boost pressure Pc and the required duty Drq to the ejector relative pressure setting map. The map for setting the relative pressure of the ejector is predetermined by experiments and analysis as the relationship between the value obtained by subtracting the intake pressure Pin from the boost pressure Pc and the required duty Drq and the relative pressure Pej of the ejector, and is stored in a ROM or flash memory (not shown). ing. FIG. 12 is an explanatory diagram showing an example of an ejector relative pressure setting map. As shown in the figure, the ejector relative pressure Pej increases as the required duty Drq increases (the absolute value as a negative value decreases), and the boost pressure Pc (value obtained by subtracting the intake pressure Pin from the boost pressure Pc). Is set so that the larger the value, the smaller the value (the absolute value as a negative value increases).

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 S520). ). 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 experiments and analyzes 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. 13 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 relative pressure Pej of the ejector and the value obtained by subtracting the offset amount kd from the surge pressure Ps are compared (step S530). When it is determined that the ejector relative 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. It is determined that the flow (downstream purge is the dominant purge), the value 0 is set in the dominant purge flag Fpd (step S540), and this routine is terminated.

When it is determined in step S530 that the ejector relative 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. (The upstream purge is the dominant purge), the value 1 is set in the dominant purge flag Fpd (step S550), and this routine is terminated.

In the embodiment, in this way, based on the surge pressure Ps, an offset amount kd for correcting the influence of the cross-sectional area of the second purge passage on the cross-sectional area of the first purge passage 62 is set, and the ejector relative pressure Pej is set. And the value obtained by subtracting the offset amount kd from the surge pressure Ps are compared to determine which of the downstream purge and the upstream purge is the dominant purge. This makes it more appropriate to determine which of the downstream purge and the upstream purge is the dominant purge, as compared to the one that does not consider the effect of the cross-sectional area of the second purge passage on the cross-sectional area of the first purge passage 62. It can be determined.

Next, the estimation of whether or not the purge includes the upstream purge (whether it is only the downstream purge) will be described using the upstream purge estimation routine of FIG. When this routine is executed, the electronic control unit 70 first inputs surge pressures Ps (step S600). Here, a value detected by the surge pressure sensor 27a is input as the surge pressure Ps.

Subsequently, the value of the upstream purge estimation flag Fpup is examined (step S610). Here, the upstream purge estimation flag Fpup is a flag set in this routine, and a value 1 is set when the purge is estimated to include the upstream purge, and the purge does not include the upstream purge (only the downstream purge). When it is estimated that there is), the value 0 is set. The upstream purge estimation flag Fpup is set to a value of 0 as an initial value when the trip is started. Further, in the embodiment, since this routine is repeatedly executed regardless of whether or not the purge condition is satisfied, the upstream purge estimation flag Fpup when the purge is not executed is assumed to be executed. Is the value of.

When the upstream purge estimation flag Fpup has a value of 0, that is, when it is estimated that the purge does not include the upstream purge (only the downstream purge), the surge pressure Ps and the threshold Psref are compared (step S620). Here, the threshold value Psref is a threshold value used for estimating whether or not the purge includes an upstream purge, and is predetermined by experiment or analysis. As the threshold value Psref, for example, about -6 to -9 kPa is used.

When it is determined in step S620 that the surge pressure Ps is less than the threshold value Psref, it is estimated that the purge does not include the upstream purge, and this routine is terminated without switching the upstream purge estimation flag Fpup (holding it at a value of 0). do. When it is determined that the surge pressure Ps is equal to or higher than the threshold value Psref, it is estimated that the purge includes the upstream purge, the upstream purge estimation flag Fpup is switched to the value 1 (step S630), and this routine is terminated.

When the upstream purge estimation flag Fpup has a value of 1 in step S610, that is, when it is estimated that the purge includes the upstream purge, the surge pressure Ps and the threshold value Psref are compared (step S640). When it is determined that the surge pressure Ps is equal to or higher than the threshold value Psref, it is estimated that the purge includes the upstream purge, and this routine is terminated without switching the upstream purge estimation flag Fpup (held at a value of 1).

When it is determined 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 S650). Then, 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 that the purge includes the upstream purge, and the upstream purge estimation flag Fpup is not switched (held at a value of 1). ), End this routine. When it is determined that T1 has elapsed for a predetermined time after the surge pressure Ps reaches the threshold value Psref, it is estimated that the purge does not include the upstream purge (only the downstream purge), and the upstream purge estimation flag Fpup is switched to the value 0. (Step S660), this routine is terminated.

FIG. 14 is an explanatory diagram showing an example of the state of the surge pressure Ps and the upstream purge estimation flag Fpup. As shown in the figure, when the upstream purge estimation flag Fpup reaches a value of 0 and the surge pressure Ps reaches the threshold value Psref or higher (time t11), the upstream purge estimation flag Fpup is switched to a value of 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 upstream purge estimation flag Fpup is switched to the value 0.

The predetermined time T1 is the time until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) during the upstream purge and the time until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) during the downstream purge. It is determined by experiment and analysis as the difference from the time of. Since the path for the evaporated fuel gas to reach the surge tank 27 during the upstream purge is longer than the path for the evaporated fuel gas to reach the surge tank 27 during the downstream purge, it evaporates during the upstream purge. The time required for the fuel gas to reach the surge tank 27 is longer than the time required for the evaporated fuel gas to reach the surge tank 27 during downstream purging. Therefore, when the surge pressure Ps reaches the threshold Psref from the state of the threshold Psref or higher and reaches the threshold Psref for a while (see time t12 to t13 in FIG. 14), the vaporized fuel gas remaining in the second purge passage 63 It is assumed that the evaporative fuel gas newly supplied to the first 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 upstream purge estimation flag Fpup has a value of 1, the upstream purge estimation flag Fpup is set to a value of 0 after waiting for a predetermined time T1 to elapse after the surge pressure Ps reaches the threshold value Psref. I decided to switch. This makes it possible to more appropriately estimate whether or not the purge includes an upstream purge (whether it is only a downstream purge).

Next, the purge control will be described with reference to the purge control routine of FIG. When this routine is executed, the electronic control unit 70 first inputs data such as an intake air amount Qa, an intake pressure Pin, a boost pressure Pc, and a surge pressure Ps (step S400). 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.

Subsequently, it is determined whether or not the purge condition is satisfied (step S402). Here, as the purge condition, for example, the operation control of the engine 12 (fuel injection control, etc.) is performed, and the current load factor KL of the plurality of load factor regions Rk [1] to Rk [n] is used. The condition that the setting completion flag Fα [i] of the belonging area (area number i) to which the member belongs is a value 1 (the air-fuel ratio correction amount α [i] has already been set in the current trip) is used. When it is determined that the purge condition is not satisfied, this routine is terminated. In this case, as described above, the required purge rate Rprq is set to a value of 0, and the purge control valve 65 is closed.

When it is determined in step S402 that the purge condition is satisfied, the target purge rate Rptg is set (step S410). Here, the target purge rate Rptg is gradually set from the start purge rate Rpst1 (for example, during the period from the start of the establishment of the purge condition to the interruption or the end) of the first establishment of the purge condition in each trip. , By rate processing using the rate value ΔRp1). Further, the target purge rate Rptg gradually increases from the restart purge rate Rpst2 during the second and subsequent establishment periods of the purge condition (the period from the resumption of the establishment of the purge condition to the interruption or termination) in each trip. For example, it is set to be larger (by rate processing using the rate value ΔRp2). As the start purge rate Rpst1 and the restart purge rate Rpst2, relatively small values are used in order to suppress the disturbance of the air-fuel ratio of the engine 12.

Subsequently, the upper limit purge rate Rplim is set by the upper limit purge rate setting routine described later (step S420). Then, the fully open purge flow rate Qpmax is estimated based on the surge pressure Ps and the value obtained by subtracting the intake pressure Pin from the boost pressure Pc (step S430). Here, the fully open purge flow rate Qpmax is the 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 Qpmax 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 Qpmax, and is stored in a ROM or flash memory (not shown). ing. FIG. 15 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 Qpmax 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 pre-purge flow rate (past Qpv) before the predetermined time T2 (step S440). Here, the pre-valve purge flow rate Qpv is the flow rate of the evaporated fuel gas on the introduction passage 52 side of the purge control valve 65 of the common passage 61. The pre-valve purge flow rate (past Qpv) before the predetermined time T2 was estimated by the process of step S490 described later when this routine was executed before the predetermined time T2 when purging was executed before the predetermined time T2. A value of 0 is used when the value is used and the purge is not performed before T2 for a predetermined time. The predetermined time T2 is set as the time required for the evaporated fuel gas on the introduction passage 52 side of the purge control valve 65 of the common passage 61 to reach the combustion chamber 30, and the control purge flag Fpd and the upstream purge estimation flag Fpup are used. A time based on the number of revolutions Ne of the engine 12 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 pre-valve purge flow rate (past Qpv) to the combustion chamber air amount estimation map. The map for estimating the combustion chamber air amount is predetermined by experiments and analysis as the relationship between the intake air amount Qa and the past pre-valve 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 Qpmax and the combustion chamber air amount Qcc are estimated in this way, the fully open purge rate Rpmax is estimated based on these (step S450). Here, the fully open purge rate Rpmax can be calculated by dividing the fully open purge flow rate Qpmax by the amount of air in the combustion chamber Qcc. Subsequently, the target purge rate Rptg is limited (upper limit guard) by the fully open purge rate Rpmax and the upper limit purge rate Rplim to set the required purge rate Rprq (step S460). That is, the smallest value among the target purge rate Rptg, the fully open purge rate Rpmax, and the upper limit purge rate Eplim is set in the required purge rate Rprq. Then, the required purge rate Rprq is divided by the fully open purge rate Rpmax to set the required duty Drq of the purge control valve 65 (step S470), and the purge control valve 65 is controlled using the set required duty Drq (step S480). ..

Then, the pre-valve purge flow rate Qpv is estimated based on the intake air amount Qa and the required purge rate Rprq (step S490), and this routine is terminated. Here, the pre-valve purge flow rate Qpv can be obtained by applying, for example, the intake air amount Qa and the required purge rate Rprq to the pre-valve purge flow rate estimation map. The map for estimating the pre-valve purge flow rate is predetermined by experiments and analyzes as the relationship between the intake air amount Qa and the required purge rate Rprq and the pre-valve purge flow rate Qpv, and is stored in a ROM or flash memory (not shown).

Next, the process of step S420 of the purge control routine of FIG. 9, specifically, the process of setting the upper limit purge rate Rplim will be described. FIG. 16 is a flowchart showing an example of an upper limit purge rate setting routine for setting the upper limit purge rate Rplim. When this routine is executed, the electronic control unit 70 first inputs data such as the supply fuel pressure Pfd of the in-cylinder injection valve 28, the purge concentration related value Cp, and the upstream purge estimation flag Fpup (step S700). Here, a value detected by the fuel pressure sensor 28a is input to the supply fuel pressure Pfd of the in-cylinder injection valve 28. As the purge concentration-related value Cp, the value set by the purge correction amount setting routine of FIG. 7 is input. The value set by the upstream purge estimation routine of FIG. 10 is input to the upstream purge estimation flag Fpup.

When data is input in this way, the permissible limit rate Rcdp1 of the purge rate that can suppress the deposit from adhering to the in-cylinder injection valve 28 during downstream purging and upstream purging based on the supply fuel pressure Pfd of the in-cylinder injection valve 28 Rcdp2 is set (step S710). As described above, when the purge concentration-related value Cp is a negative value, the larger the required purge rate Rprq, the smaller the purge correction amount β (the absolute value as a negative value becomes larger), and the in-cylinder injection valve 28 The required injection amount Qf * is reduced. When the required injection amount Qf * (fuel injection amount) of the in-cylinder injection valve 28 becomes small, the tip temperature of the in-cylinder injection valve 28 rises, and a deposit is likely to adhere to the in-cylinder injection valve 28. The absolute value of the permissible limit rate Rcdp1 and Rcdp2 means the permissible upper limit value of the purge rate that can suppress the deposit from adhering to the in-cylinder injection valve 28. In the embodiment, the permissible limit rates Rcdp1 and Rcdp2 are set as negative values. The reason for this will be described later.

The permissible limit rates Rcdp1 and Rcdp2 can be obtained by applying the supply fuel pressure Pfd of the in-cylinder injection valve 28 to the in-cylinder injection valve protection map. The in-cylinder injection valve protection map is predetermined by experiments and analysis as the relationship between the supply fuel pressure Pfd of the in-cylinder injection valve 28 and the allowable limit rates Rcdp1 and Rcdp2, and is stored in a ROM (not shown). FIG. 17 is an explanatory diagram showing an example of an in-cylinder injection valve protection map. As shown in the figure, the permissible limit rate Rcdp1 and Rcdp2 have a larger absolute value as the supply fuel pressure Pfd of the in-cylinder injection valve 28 is higher in the negative range, and the permissible limit rate Rcdp2 is compared with the permissible limit rate Rcdp1. And the absolute value is set to be small. The former is based on the fact that the higher the supply fuel pressure Pfd of the in-cylinder injection valve 28, the less likely it is that a deposit adheres to the in-cylinder injection valve 28 (even if it adheres, it becomes easier to blow off). In the latter, in the upstream purge (when the boost pressure Pc is large), the air compressed by the compressor 41 of the supercharger 40 is sucked into the combustion chamber 30 as compared with the downstream purge (when the boost pressure Pc is small). This is based on the fact that the temperature of the combustion chamber 30 tends to rise and the deposit tends to adhere to the in-cylinder injection valve 28.

Subsequently, the permissible limit rate Rcsp of the purge rate of the downstream purge capable of suppressing the rich engine stall of the engine 12 is set (step S720). As described above, when the surge pressure Ps reaches the threshold Psref from the state of the threshold Psref or higher to less than the threshold Psref, the evaporation remaining in the second purge passage 63 for a while (see time t12 to t13 in FIG. 14). It is assumed that the fuel gas and the evaporated fuel gas newly supplied to the first purge passage 62 merge on the downstream side of the throttle valve 26 of the intake pipe 23 and are supplied to the surge tank 27 (combustion chamber 30). .. The permissible limit rate Rcsp means the permissible upper limit value of the purge rate of the downstream purge capable of suppressing the rich engine stall of the engine 12 at this time, and it is assumed that a predetermined value is set by experiments and analyzes. In the embodiment, the permissible limit rate Rcsp is also set as a negative value like the permissible limit rates Rcdp1 and Rcdp2. The reason for this will also be described later.

Subsequently, the value of the purge concentration-related value Cp is examined (step S730). Then, when the purge concentration-related value Cp is 0 or more, a predetermined value Rplim1 is set in the upper limit purge rate Rplim (step S740), and this routine is terminated. Here, a sufficiently large value is used as the predetermined value Rplim1. This is to avoid an unexpected decrease in the required purge rate Rprq in step S460 of the purge control routine of FIG.

When the purge concentration-related value Cp is less than 0 (negative value) in step S730, it is determined whether or not the dominant purge flag Fpd can be input (step S750). This processing is performed, for example, by determining whether or not the dominant purge flag Fpd is set by the dominant purge determination routine of FIG. 10 after the establishment of the purge condition is started or restarted. Considering in chronological order, the processing is in the order of processing when the dominant purge flag Fpd cannot be input and processing when it can be input, but for ease of explanation, processing when the dominant purge flag Fpd can be input and input is possible. This will be explained in the order of processing when it is not.

When it is determined in step S750 that the dominant purge flag Fpd can be input, the dominant purge flag Fpd is input (step S790), and the value of the dominant purge flag Fpd is checked (step S800). Then, when the dominant purge flag Fpd has a value of 0, that is, when the downstream purge is the dominant purge, the value of the upstream purge estimation flag Fpup is examined (step S810). When the upstream purge estimation flag Fpup has a value of 0, that is, when it is estimated that the purge does not include the upstream purge (only the downstream purge), the upper limit is the value obtained by dividing the allowable limit rate Rcdp1 by the purge concentration-related value Cp. The purge rate is set to Rplim (step S820), and this routine is terminated. Here, since the permissible limit rate Rcdp1 and the purge concentration-related value Cp are both negative values, the upper limit purge rate Rplim increases as the absolute value of the permissible limit rate Rcdp1 increases, and the purge concentration-related value Cp is absolute. The larger the value, the smaller the value. In the embodiment, the permissible limit rate Rcdp1 is set to a negative value so that the upper limit purge rate Rplim becomes a positive value. By setting the upper limit purge rate Rplim in this way, it is possible to prevent the deposit from adhering to the in-cylinder injection valve 28 when the purge is only the downstream purge.

When the dominant purge flag Fpd is a value 1 in step S800, that is, when the upstream purge is a dominant purge, the value obtained by dividing the allowable limit rate Rcdp2 by the purge concentration-related value Cp is set as the upper limit purge rate Rplim (step S830). , End this routine. Here, since the permissible limit rate Rcdp2 and the purge concentration-related value Cp are both negative values, the upper limit purge rate Rplim increases as the absolute value of the permissible limit rate Rcdp2 increases, and the purge concentration-related value Cp is absolute. The larger the value, the smaller the value. Moreover, since the absolute value of the permissible limit rate Rcdp2 is smaller than the absolute value of the permissible limit rate Rcdp1, the upper limit purge rate Rplim when the upstream purge is the dominant purge is the upper limit purge when the downstream purge is the dominant purge. It is smaller than the rate Rplim. In the embodiment, the permissible limit rate Rcdp2 is set to a negative value in order to make the upper limit purge rate Rplim a positive value. By setting the upper limit purge rate Rplim in this way, it is possible to prevent deposits from adhering to the in-cylinder injection valve 28 when the upstream purge is the dominant purge.

Allowed when the dominant purge flag Fpd is a value 0 in step S800, ie the downstream purge is a dominant purge, and the upstream purge estimation flag Fpup is a value 1 in step S810, ie the purge is estimated to include an upstream purge. The value obtained by dividing the limit rate Rcsp by the purge concentration-related value Cp is set in the upper limit purge rate Rplim (step S840), and this routine is terminated. In the embodiment, the permissible limit rate Rcsp is set to a negative value in order to make the upper limit purge rate Rplim a positive value. By setting the upper limit purge rate Rplim in this way, when it is estimated that the downstream purge is dominant and the purge includes the upstream purge, specifically, it remains in the second purge passage 63. When the evaporative fuel gas and the evaporative fuel gas newly supplied to the first purge passage 62 merge on the downstream side of the throttle valve 26 of the intake pipe 23 and are supplied to the surge tank 27 (combustion chamber 30). It is possible to suppress the occurrence of rich engine 12 engine. At this time, the inventors confirmed by experiments and analysis that the possibility of deposits adhering to the in-cylinder injection valve 28 was low.

When it is determined in step S750 that the control purge flag Fpd cannot be input, the value of the upstream purge estimation flag Fpup is examined (step S760). Then, when the upstream purge estimation flag Fpup has a value of 0, that is, when it is estimated that the purge does not include the upstream purge (only the downstream purge), the allowable limit rate Rcdp1 is purged as in the process of step S820. The value divided by the concentration-related value Cp is set in the upper limit purge rate Rplim (step S770), and this routine is terminated. In this case, the upper limit purge rate Rplim increases as the absolute value of the permissible limit rate Rcdp1 increases, and decreases as the absolute value of the purge concentration-related value Cp increases.

When the upstream purge estimation flag Fpup is set to a value 1 in step S760, that is, when it is estimated that the purge includes an upstream purge, the maximum value between the permissible limit rate Rcdp2 and the permissible limit rate Rcsp (minimum value as an absolute value). Is set to the upper limit purge rate Rplim (step S780) by dividing the value obtained by dividing by the purge concentration-related value Cp, and this routine is terminated. In this case, the upper limit purge rate Rplim becomes larger as the minimum values of the permissible limit rate Rcdp2 and the permissible limit rate Rcsp are larger, and becomes smaller as the absolute value of the purge concentration-related value Cp is larger. When the upstream purge estimation flag Fpup has a value of 1, there are cases where the upstream purge is the dominant purge and when the downstream purge is dominant and the purge is estimated to include the upstream purge. However, since the case where the control purge flag Fpd cannot be input is considered, it is not possible to distinguish between the two. Therefore, in the embodiment, the upper limit purge rate Rplim is set by using the minimum value as the absolute value of the permissible limit rate Rcdp2 and the permissible limit rate Rcsp. As a result, it is possible to suppress the deposit from adhering to the in-cylinder injection valve 28 and to suppress the occurrence of rich engine stall of the engine 12.

As described above, the purge concentration-related value Cp becomes relatively small (the absolute value as a negative value becomes large) when the purge concentration is high, such as immediately after the start or restart of the purge, and then the purge is performed. As the purge concentration continues to decrease, it gradually increases. Therefore, the upper limit purge rate Rplim becomes relatively small when the purge concentration-related value Cp is negative and the purge concentration is high, such as immediately after the start or restart of the purge, and the purge continues and the purge concentration decreases. It gradually grows as you do.

In the engine device 10 of the embodiment described above, when the purging is restarted including the second purge after the purging is interrupted, the minimum value as the absolute value of the permissible limit rate Rcdp2 and the permissible limit rate Rcsp is used. The upper limit purge rate Rplim is set, and the required purge rate Rprq is set within the range of the upper limit purge rate Rplim or less to control the purge control valve 65. Here, the permissible limit rate Rcdp2 is a permissible limit rate of the purge rate that can suppress the deposit from adhering to the in-cylinder injection valve 28 at the time of upstream purging. In the allowable limit ratio Rcsp, the evaporative fuel gas remaining in the second purge passage 63 and the evaporative fuel gas newly supplied to the first purge passage 62 merge on the downstream side of the throttle valve 26 of the intake pipe 23. This is the permissible limit rate of the purge rate of the downstream purge that can suppress the rich engine stall of the engine 12 when it is supplied to the surge tank 27 (combustion chamber 30). By such control, it is possible to suppress the deposit from adhering to the in-cylinder injection valve 28 and to suppress the occurrence of rich engine stall of the engine 12.

In the engine device 10 of the embodiment, when the dominant purge flag Fpd is a value 1, the upper limit purge rate Rplim is set using the allowable limit rate Rcdp2, the dominant purge flag Fpd is a value 0, and the upstream purge estimation flag Fpup is a value 1. Occasionally, the upper limit purge rate Rplim was set using the permissible limit rate Rcsp. However, when the dominant purge flag Fpd is a value, or when the dominant purge flag Fpd is a value 0 and the upstream purge estimation flag Fpup is a value 1, the dominant purge flag Fpd cannot be input and the upstream purge estimation flag Fpup is a value 1. As in the case, the upper limit purge rate Rplim may be set by using the minimum value as an absolute value of the permissible limit rate Rcdp2 and the permissible limit rate Rcsp.

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 instead of the in-cylinder injection valve 28, a port injection valve that injects fuel into the intake port. Even in these cases, it can be considered in the same manner as in the examples. When a port injection valve is provided instead of the in-cylinder injection valve 28, the port injection valve is generally connected to the low pressure side fuel passage 17, so that the supply fuel pressure of the port injection valve is the supply fuel pressure Pfd of the in-cylinder injection valve 28. Low compared to. Therefore, it is less likely that a deposit will adhere to the port injection valve as compared with the in-cylinder injection valve 28.

In the engine device 10 of the embodiment, the offset amount kd is set based on the surge pressure Ps, and either the downstream purge or the upstream purge is set based on the ejector relative pressure Pej and the value obtained by subtracting the offset amount kd from the surge pressure Ps. Was determined to be the dominant purge. However, it is determined which of the downstream purge and the upstream purge is the dominant purge based on the value obtained by subtracting the constant offset amount kd unrelated to the ejector relative pressure Pej and the surge pressure Ps from the surge pressure Ps. May be good. Even in this case, although the accuracy is inferior to that of the embodiment, either the downstream purge or the upstream purge is compared with the one that does not consider the influence based on the cross-sectional area of the second purge passage on the cross-sectional area of the first purge passage 62. It is possible to more appropriately determine whether it is a dominant purge.

In the engine device 10 of the embodiment, the air-fuel ratio correction amount α [1] to α [n] is set only once in one trip for each of the plurality of load factor regions Rk [1] to Rk [n]. bottom. However, the air-fuel ratio correction amount α [1] to α [n] may be set a plurality of times in one trip. In this case, the process of step S250 of the air-fuel ratio correction amount setting routine of FIG. 5 may not be executed.

In the engine device 10 of the embodiment, the range assumed for the load factor KL is divided into a plurality of load factor regions Rk [1] to Rk [n], and the plurality of load factor regions Rk [1] to Rk [n]. It was assumed that each air-fuel ratio correction amount α [1] to α [n] was set. However, instead of this, the range assumed for the intake air amount Qa is divided into a plurality of air amount regions Rq [1] to Rq [n], and the plurality of air amount regions Rq [1] to Rq [n]. The respective air-fuel ratio correction amounts α [1] to α [n] may be set.

In the engine device 10 of the embodiment, it is determined which of the downstream purge and the upstream purge is the dominant purge based on the ejector relative pressure Pej and the value obtained by subtracting the offset amount kd from the surge pressure Ps. However, it may be determined which of the downstream purge and the upstream purge is the dominant purge based on the load factor KL and the intake air amount Qa. In this case, which of the downstream purge and the upstream purge is the dominant purge is determined based on the load factor KL and the boundary value between the load factor region Rk [n-1] and the load factor region Rk [n]. Which of the downstream purge and the upstream purge is the dominant purge based on the determination or the boundary value between the intake air amount Qa and the air amount region Rq [n-1] and the air amount region Rq [n]. It may be determined whether or not.

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.

In the embodiment, the engine device 10 mounted on a general automobile or various hybrid automobiles is used. However, it may be in the form of an engine device mounted on a vehicle other than an automobile, or may be in the form of an engine device mounted on non-moving equipment such as construction equipment.

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 arranged in an intake pipe and a fuel injection valve and outputs power using fuel supplied from a 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.
When executing a purge for supplying the evaporated fuel gas to the intake pipe, a control device that controls the purge control valve by setting a required purge rate within the range of the upper limit purge rate or less.
It is an engine device equipped with
When the control device interrupts the purge and then restarts the purge including a second purge that supplies the evaporated fuel gas to the intake pipe through the second purge passage, a deposit is made on the fuel injection valve. The first permissible limit rate of the purge rate capable of suppressing the adhesion of the gas, the evaporated fuel gas remaining in the second purge passage, and the evaporated fuel gas newly supplied to the first purge passage are the intakes. The purge rate of the first purge that supplies the evaporated fuel gas to the intake pipe through the first purge passage, which can suppress the rich entanglement of the engine when merging on the downstream side of the throttle valve of the pipe. The upper limit purge rate is set based on the second allowable limit rate and the minimum value as an absolute value.
Engine device.

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