JP2022012630A - Engine device - Google Patents

Abstract

To suppress variation of an air-fuel ratio among cylinders of an engine.SOLUTION: An engine device comprises a multi-cylinder engine, a turbocharger, an evaporative fuel treatment device, and a control device that controls a purging control valve based on a required purging rate when performing purging of supplying evaporative fuel gas to a combustion chamber via an intake pipe. In a supercharging region, the control device sets the required purging rate within a range equal to or less than an upper limit purging rate for limiting the variation of the evaporated fuel gas supplied to the combustion chamber of each cylinder. Consequently, it is possible to suppress variation of an amount of the evaporated fuel gas supplied to the combustion chamber of each cylinder, and to suppress variation of an air-fuel ratio between the cylinders.SELECTED DRAWING: Figure 3

Description

The present invention relates to an engine device.

Conventionally, as this type of engine device, a first purge passage for purging the evaporated fuel gas containing the evaporated fuel and a boost pressure from the compressor of the supercharger are used on the downstream side of the throttle valve of the intake pipe of the engine. The second purge passage that purges the evaporated fuel gas upstream of the compressor of the intake pipe by the ejector that generates negative pressure, and the evaporated fuel gas generated in the fuel tank are supplied to the first purge passage and the second purge passage. It has been proposed to include a supply passage and a purge control valve provided in the supply passage (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 the first control characteristic data suitable for the first purge passage and the second purge passage. Switch with the second control characteristic data suitable for.

Japanese Unexamined Patent Publication No. 2019-052561

In such an engine device, when the purge passage is the second purge passage, the path volume from the vaporized fuel gas passing through the purge control valve to the combustion chamber is higher than that when the purge passage is the first purge passage. Because of the large size, the flow of fluid is likely to be disturbed in the intake pipe or the like, the amount of fuel vapor gas supplied to the combustion chamber of each cylinder is likely to vary, and the air-fuel ratio is likely to vary between cylinders. And, these variations tend to increase as the amount of evaporated fuel gas increases.

The main object of the engine device of the present invention is to suppress the variation in the air-fuel ratio between the cylinders of the engine.

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
A multi-cylinder engine that has a throttle valve located in the intake pipe and outputs power by explosive combustion in the combustion chamber of each cylinder 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.
When performing a purge in which the vaporized fuel gas is supplied to the combustion chamber via the intake pipe, a control device that controls the purge control valve based on the required purge rate and a control device.
It is an engine device equipped with
In the supercharging region, the control device sets the required purge rate within a range equal to or less than the upper limit purge rate for limiting the variation of the evaporated fuel gas supplied to the combustion chamber of each cylinder.
The gist is that.

In the engine device of the present invention, when purging to supply the evaporative fuel gas to the combustion chamber via the intake pipe is performed, the purge control valve is controlled based on the required purge rate. The required purge rate is set within the range of the upper limit purge rate or less for limiting the variation in the evaporative fuel gas supplied to the combustion chamber. As a result, it is possible to suppress the amount of the evaporated fuel gas supplied to the combustion chamber of each cylinder from fluctuating, and to suppress the air-fuel ratio from fluctuating between the cylinders.

In the engine device of the present invention, the control device is required to be within the range of the upper limit purge rate or less for limiting the variation of the evaporated fuel gas supplied to the combustion chamber of each cylinder even in the naturally aspirated region. The purge rate may be set, and the upper limit purge rate in the supercharged area may be smaller than the upper limit purge rate in the naturally aspirated area.

In the engine device of the present invention, when the throttle rear pressure, which is the pressure downstream of the throttle valve of the intake pipe, is less than the threshold value, the control device presumes that it is in the naturally aspirated region, and the throttle rear pressure is When the throttle post-pressure reaches from the threshold value or more to less than the threshold value in the estimation process of presuming that the throttle is in the supercharging area when the pressure is equal to or higher than the threshold value, the supercharging region is determined to be in the supercharging region until a predetermined time elapses. The estimation may be continued.

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 purge control routine. It is a flowchart which shows an example of the supercharging area determination routine for determining which of the naturally aspirated area and the supercharging area. 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. It is explanatory drawing which shows an example of the relationship between the drive energization time of a purge control valve 65, and the purge flow 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 as a control device.

The engine 12 is configured as a multi-cylinder (for example, 4-cylinder, 6-cylinder, etc.) 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. In the intake air amount control, the throttle valve 26 is controlled so that the throttle opening TH becomes smaller as the flow rate of the evaporated fuel gas supplied to the intake pipe 23 increases with the purge control. In the fuel injection control, the cylinder so that the fuel injection amount decreases as the flow rate of the evaporated fuel gas supplied to the intake pipe 23 in accordance with the purge control increases (the air-fuel ratio of the engine 12 becomes richer accordingly). The internal injection valve 28 is controlled.

Next, the operation of the engine device 10 of the embodiment, particularly the purge control, will be described. FIG. 3 is a flowchart showing an example of a purge control routine, and FIG. 4 is a flowchart showing an example of a supercharging area determination routine for determining which of the naturally aspirated area and the supercharging area. .. 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.

The purge control routine of FIG. 3 is repeatedly executed by the electronic control unit 70 when the purge condition is satisfied. Here, as the purge condition, for example, a condition 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 is used. As the threshold value Twref, for example, about 55 ° C. to 65 ° C. is used. The supercharging area determination routine of FIG. 4 is repeatedly executed by the electronic control unit 70. Hereinafter, for the sake of simplicity, the determination of whether the engine is in the naturally aspirated region or the supercharged region will be described using the supercharging region determination routine of FIG. 4, and then the purge control based on this determination will be described. This will be described using the purge control routine of FIG.

The determination of which of the naturally aspirated region and the supercharged region is described will be described using the supercharging region determination routine of FIG. When this routine is executed, the electronic control unit 70 first inputs the surge pressure Ps (step S300). 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 S310). Here, the supercharged area flag Fc is set to a value 0 when it is determined that it is a naturally aspirated area (the purge does not include the upstream purge when the purge is being executed), and it is the supercharged area (purge). A value of 1 is set when it is determined that the purge includes the upstream purge during execution. Further, the supercharged area flag Fc is set to a value of 0 as an initial value when the current trip is started.

When the value of the previous supercharging area flag (previous Fc) is 0, that is, when it is determined that the previous time is the naturally aspirated area, the surge pressure Ps and the threshold value Psref are compared (step S320). Here, the threshold value Psref is a threshold value used for determining whether the engine is in the naturally aspirated region or the supercharged region, 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 S320 that the surge pressure Ps is less than the threshold value Psref, it is determined that the surge pressure Ps is 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 S330). End this routine. When it is determined in step S320 that the surge pressure Ps is equal to or greater than the threshold value Psref, it is determined that the surge pressure Ps is in the supercharging region, and the value 1 is set in the supercharging region flag Fc, that is, the value is switched from 0 to 1 (step S360). ), End this routine.

When the previous supercharging area flag (previous Fc) has a value of 1 in step S310, that is, when it is determined to be the supercharging area last time, the surge pressure Ps and the threshold value Psref are compared (step S340). When it is determined that the surge pressure Ps is equal to or higher than the threshold value Psref, it is determined that the surge pressure Ps is in the supercharging region, a value 1 is set in the supercharging region flag Fc, that is, the value is held at 1 (step S360), and this routine is performed. finish.

When it is determined in step S340 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 S350). 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 determined that the turbocharging region is in the supercharging region, and the value 1 is set in the supercharging region flag Fc, that is, the value is held at 1. (Step S360), 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 determined that the engine is 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 S330), this routine is terminated.

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. The path volume until the evaporative fuel gas reaches the surge tank 27 (combustion chamber 30) via the second purge passage 63 and the intake pipe 23 during the upstream purge (with substantially the entire second purge passage 63 and the intake pipe 23). The path volume based on the above is the path volume (with the first purge passage 62) until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) via the first purge passage 62 and the intake pipe 23 during downstream purging. It is larger than the path volume based on the portion of the intake pipe 23 downstream of the throttle valve 26). Therefore, the time required for the evaporated fuel gas to reach the surge tank 27 (combustion chamber 30) during the upstream purge is until the evaporated fuel gas reaches the surge tank 27 (combustion chamber 30) during the downstream purge. It will be longer than time. 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. Thereby, it is possible to more appropriately determine which of the naturally aspirated region and the supercharged region.

FIG. 5 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.

Next, the purge control will be described using the purge control routine of FIG. When this routine is executed, the electronic control unit 70 first inputs data such as the intake air amount Qa, the intake pressure Pin, the supercharging pressure Pc, the surge pressure Ps, and the supercharging area flag Fc (step S100). .. 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 value set by the supercharging area determination routine of FIG. 4 is input to the supercharging area flag Fc.

When the data is input in this way, 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 S110), and the fully open purge flow rate Qpmax is divided by the intake air amount Qa. The upper limit purge rate Rplim is estimated (step S120). 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. FIG. 6 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. "Purge rate" means the ratio of the amount of evaporative fuel gas to the amount of intake air.

Subsequently, the supercharged area flag Fc is examined (step S130). When the supercharging area flag Fc has a value of 0, that is, when it is determined that the area is a naturally aspirated area (the purge does not include the upstream purge when the purge is being executed), the target purge rate Rptg is set and (step). S140), the value Qp1 is divided by the intake air amount Qa to set the upper limit purge rate Rplim (step S150). When the supercharged area flag Fc has a value of 1, that is, when it is determined that the supercharged area is in the supercharged area (the purge includes the upstream purge when the purge is being executed), the target purge rate Rptg is set and the target purge rate Rptg is set (step S160). ), The value Qp2 smaller than the value Qp1 is divided by the intake air amount Qa to set the upper limit purge rate Rplim (step S170).

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. Further, at least one of the start purge rate Rpst1, the restart purge rate Rpst2, and the rate values ΔRp1 and ΔRp2 has a ratio when the supercharging area flag Fc is a value 1 and when the supercharging area flag Fc is a value 0. And a small value is set. When the establishment of the purge condition is interrupted, for example, the accelerator is turned off while the vehicle on which the engine device 10 is mounted is running to cut the fuel of the engine 12 (the operation control of the engine 12 is interrupted). There are times, etc. "Purge rate" means the ratio of the amount of evaporative fuel gas to the amount of intake air.

Further, the values Qa1 and Qa2 are predetermined by experiments and analyzes as values for limiting the variation of the evaporated fuel gas supplied to the combustion chamber 30 of each cylinder of the engine 12. When the purge is being executed, the evaporative fuel gas is purge-controlled when it is in the supercharged region (purge includes the upstream purge) compared to when it is in the naturally-intake region (purge does not include the upstream purge). Since the path volume from passing through the valve 65 to the combustion chamber 30 is large, the flow of fluid is likely to be disturbed in the intake pipe 23 or the like, and the amount of evaporative fuel gas supplied to the combustion chamber 30 of each cylinder is likely to vary. , The air-fuel ratio tends to vary between cylinders. And, these variations tend to increase as the amount of evaporated fuel gas increases. The turbulence of the fluid in the intake pipe 23 is more likely to occur when the portion of the intake pipe 23 from the compressor 41 to the combustion chamber 30 is distorted. Therefore, the value Qa2 is defined as a value smaller than the value Qa1. In this way, the upper limit purge rate Rplim when the supercharging area flag Fc is a value 1 is set to a smaller value than the upper limit purge rate Rplim when the supercharging area flag Fc is a value 0.

When the upper limit purge rate Rplim is set in this way, the target purge rate Rptg is limited by the fully open purge rate Rpmax and the upper limit purge rate Rplim (upper limit guard), and the provisional request purge rate Rprqtpp is set as a provisional value of the request purge rate Rprq (step). S180). That is, the minimum value of the target purge rate Rptg, the fully open purge rate Rpmax, and the upper limit purge rate Rplim is set in the provisional request purge rate Rprqtpm.

Subsequently, a value obtained by dividing the lower limit energization time Tmin of the purge control valve 65 by the drive cycle Tprd of the purge control valve 65 is set as the lower limit duty Dmin of the purge control valve 65 (step S190). Here, the lower limit energization time Tmin of the purge control valve 65 is a time during which the relationship between the time after the purge control valve 65 is opened (drive energization time) and the purge flow rate switches linearly from non-linear. FIG. 7 is an explanatory diagram showing an example of the relationship between the drive energization time of the purge control valve 65 and the purge flow rate. As shown in the figure, as a characteristic of the purge control valve 65, when the drive energization time is less than the lower limit energization time Tmin, the relationship between the drive energization time and the purge flow rate becomes non-linear, and the drive energization time reaches the lower limit energization time Tmin or more. , The relationship between the drive energization time and the purge flow rate becomes linear.

When the lower limit duty Dmin of the purge control valve 65 is set in this way, the product of the above-mentioned fully open purge rate Rpmax and the lower limit duty Dmin is set to the lower limit purge rate Rpmin (step S200). As described above, since the lower limit energization time Tmin of the purge control valve 65 is the time when the relationship between the drive energization time of the purge control valve 65 and the purge flow rate switches linearly from non-linear, the lower limit purge rate Rpmin is the purge control valve. It means a purge rate in which the relationship between the drive energization time of 65 and the purge flow rate is linearly switched from non-linear to linear (the lower limit of the purge rate range in which the purge flow rate can be accurately controlled by controlling the opening degree Opv of the purge control valve 65).

Subsequently, the provisional request purge rate Rprqtpm is compared with the lower limit purge rate Rpmin (step S210). When the provisional request purge rate Rprqtmp is equal to or higher than the lower limit purge rate Rpmin, the provisional request purge rate Rprqtpp is set to the required purge rate Rprq (step S220), and the value obtained by dividing the required purge rate Rprq by the fully open purge rate Rpmax is the purge control valve 65. It is set to the drive duty Ddr of (step S240). Then, the purge control valve 65 is controlled using the set drive duty Ddr (step S250), and this routine is terminated.

In this case, the provisional request purge rate Rprqtpm in which the minimum values of the target purge rate Rptg, the fully open purge rate Rpmax, and the upper limit purge rate Rplim are set is set as the request purge rate Rprq. Therefore, in the naturally aspirated region, the required purge rate Rprq is set within the range of the upper limit purge rate Rplim or less obtained by dividing the value Qp1 by the intake air amount Qa to control the purge control valve 65, and in the supercharging region. It can be said that the purge control valve 65 is controlled by setting the required purge rate Rprq within the range of the upper limit purge rate Rplim or less obtained by dividing the value Qp2 smaller than the value Qp1 by the intake air amount Qa. As a result, it is possible to suppress variations in the evaporated fuel gas supplied to the combustion chamber 30 of each cylinder of the engine 12 in the naturally aspirated region and the supercharging region. When the portion of the intake pipe 23 from the compressor 41 to the combustion chamber 30 is distorted, as described above, the turbulence of the fluid in the intake pipe 23 is more likely to occur, so that the significance of performing such a process is greater.

Further, in the embodiment, as described above, when the supercharged area flag Fc has a value of 1, the start purge rate used for setting the target purge rate Rptg is compared with the case where the supercharged area flag Fc has a value of 0. At least one of Rpst1, the restart purge rate Rpst2, and the rate values ΔRp1 and ΔRp2 is set to a small value. In the supercharged region (purge includes upstream purge), compared to in the naturally aspirated region (purge does not include upstream purge), the evaporative fuel gas passes through the purge control valve 65 before the combustion chamber. Due to the large path volume up to 30 and the fluctuation of the supercharging pressure Pc, the front air-fuel ratio AF1 tends to become unstable due to the fuel injection control. Based on this, when the supercharging area flag Fc has a value of 1, the start purge rate Rpst1, the restart purge rate Rpst2, and the rate values ΔRp1 and ΔRp2 are smaller than when the supercharging area flag Fc has a value of 0. Therefore, by reducing the target purge rate Rptg, it is possible to suppress the instability of the front air-fuel ratio AF1.

When the provisional request purge rate Rprqtp is less than the lower limit purge rate Rpmin in step S210, the value 0 is set to the request purge rate Rprq (step S230), and the request purge rate Rprq is divided by the fully open purge rate Rpmax, that is, the value 0. Is set to the drive duty Ddr of the purge control valve 65 (step S240). Then, the purge control valve 65 is controlled using the set drive duty Ddr (step S250), and this routine is terminated. This makes it possible to avoid controlling the purge control valve 65 within a range in which the purge flow rate cannot be controlled accurately.

In the engine device 10 of the embodiment described above, in the supercharging region, an upper limit based on a predetermined value Qa2 as a value for limiting the variation of the vaporized fuel gas supplied to the combustion chamber 30 of each cylinder of the engine 12 The required purge rate Rprq is set within the range of the purge rate Rplim or less to control the purge control valve 65. As a result, it is possible to suppress variations in the evaporated fuel gas supplied to the combustion chamber 30 of each cylinder of the engine 12 in the supercharging region.

In the engine device 10 of the embodiment, the description of the hardware configuration of the engine 12 is omitted, but the engine 12 is configured as a V-type engine, and the portion of the intake pipe 23 upstream of the intercooler 25 and the exhaust pipe 35. , Two superchargers 40 are provided for the first bank and two for the second bank (corresponding to each bank), and the portion of the intake pipe 23 downstream of the intercooler 25 is the first. , It may be provided as a second bank shared. In this case, the first purge passage 62 of the evaporative fuel processing device 50 is connected to a portion of the intake pipe 23 shared by the first and second banks (a portion downstream of the intercooler 25, the same as in FIG. 1). The return passage 68 and the ejector 69 may be connected to a portion of the intake pipe 23 provided for the first bank (a portion upstream of the intercooler 25). In the engine 12 having such a hard configuration, the amount of evaporative fuel gas tends to vary between the cylinders of the engine 12 in the supercharging region, particularly between the cylinders of the first bank and the cylinders of the second bank, and the air-fuel ratio is high. Easy to vary. Therefore, it is more significant to control the purge control valve 65 by appropriately determining the above-mentioned value Qa2 and setting the required purge rate Rprq within the range of the upper limit purge rate Rplim or less based on the value Qa2 in the supercharging region. big.

In the engine apparatus 10 of the embodiment, the target purge rate Rptg (at least one of the start purge rate Rpst1, the restart purge rate Rpst2, the rate values ΔRp1, ΔRp2) and the upper limit purge rate Rplim (at least one of the start purge rate Rpst1, the restart purge rate Rpst2, and the rate values ΔRp1 and ΔRp2) are based on the supercharged area flag Fc. The value Qp1 / Qa or the value Qp2 / Qa) was set to be different. However, at least the upper limit purge rate Rplim may be different based on the supercharged area flag Fc. Therefore, the target purge rate Rptg may be the same regardless of the supercharged area flag Fc, and the supercharged area flag Fc may be the same. The parameters related to the control of the purge control valve 65 other than the target purge rate Rptg and the upper limit purge rate Rplim may be different based on the above.

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.

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 equipment, 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 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, 23t intake air temperature 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 Purifier, 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 1st purge passage, 63 2nd purge passage, 63a OBD sensor, 64 buffer part, 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)

A multi-cylinder engine that has a throttle valve located in the intake pipe and outputs power by explosive combustion in the combustion chamber of each cylinder 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.
When performing a purge in which the vaporized fuel gas is supplied to the combustion chamber via the intake pipe, a control device that controls the purge control valve based on the required purge rate and a control device.
It is an engine device equipped with
In the supercharging region, the control device sets the required purge rate within a range equal to or less than the upper limit purge rate for limiting the variation of the evaporated fuel gas supplied to the combustion chamber of each cylinder.
Engine equipment.

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