JP6815073B2 - Fuel evaporative gas treatment device - Google Patents

Description

The present invention relates to a fuel evaporative gas treatment device provided in a vehicle equipped with a turbocharged engine, and which can secure a purge gas flow rate even during supercharging with a particularly simple configuration.

In vehicles such as automobiles that use volatile liquid fuel such as gasoline, a fuel evaporative gas treatment device having a charcoal canister (hereinafter simply referred to as "canister") for the purpose of suppressing the emission of fuel evaporative gas to the outside of the vehicle. Is provided.
The canister temporarily adsorbs the fuel evaporative gas with activated carbon, introduces the fuel evaporative gas as a purge gas into the intake pipe when the engine is operating, and burns the fuel together with the air-fuel mixture (fresh air).
The purge gas is generally introduced by using the negative pressure of the intake pipe in the intake manifold or the like.

In recent years, for the purpose of improving the fuel consumption rate, etc., the displacement has been reduced compared to the engine installed in conventional models with the same vehicle weight, and supercharging down has been used to secure torque in the medium and high load range. A concept called sizing is widespread.
In such a supercharged downsizing engine, the supercharged region is frequently used even during normal driving, and the negative pressure in the intake manifold is often small or positive pressure. In the fuel vapor treatment apparatus, it is not possible to secure the flow rate of the purge gas introduced from the canister into the intake pipe, and there is a concern that the purging of the canister may be hindered.

As a conventional technique for securing the purge gas flow rate of a supercharged engine, for example, in Patent Document 1, a three-way valve to which a purge passage is connected is provided in the middle of a bypass passage that bypasses between the upstream and downstream of a compressor of a supercharger, and intake air is taken. When the negative pressure in the pipe is generated, the purge passage is communicated to the downstream side of the compressor, and when supercharging does not generate the negative pressure in the intake pipe, the purge passage is communicated to the upstream side of the compressor. It is also stated that purging should be performed.

Further, in Patent Document 2, a throttle portion is provided in a recirculation passage for returning pressurized air on the downstream side of the supercharger to the upstream side, and a purge passage is connected to the throttle portion to generate the throttle portion. It is described that negative pressure is used to promote suction of purge gas.

Japanese Patent Application Laid-Open No. 11-182369 JP-A-2009-74518

In the technique described in Patent Document 1, even if the purge passage is communicated to the upstream side of the compressor by switching the three-way valve, the negative pressure on the upstream side of the compressor is usually the negative pressure of the intake pipe of the existing naturally aspirated engine. Since it is small compared to other factors, it is difficult to secure a sufficient flow rate of purge gas during supercharging.
On the other hand, as in the technique described in Patent Document 2, when a throttle portion is provided in the reflux passage to generate a negative pressure and the purge gas is sucked, the purge gas flow rate can be increased, but the throttle gas flow rate can be increased. It is necessary to add new parts, etc., which increases the number of engine components and complicates the structure.
In view of the above-mentioned problems, an object of the present invention is to provide a fuel evaporative gas treatment apparatus capable of ensuring a purge gas flow rate even during supercharging with a simple configuration.

The present invention solves the above-mentioned problems by the following solutions.
Invention, the required torque setting means for setting a required torque of the engine, Yes, and torque the request generated by the engine compressor for compressing is driven by the turbine and the turbine driven by the exhaust air according to claim 1 A turbocharger whose boost pressure is controlled to approach torque, a bypass flow path that extracts a part of air from the outlet side of the compressor and recirculates it to the inlet side of the compressor, and a recirculation of air by the bypass flow path. A fuel evaporative gas treatment device provided in an engine provided with an air bypass valve capable of switching between an open state that enables the operation and a closed state that substantially closes the bypass flow path, and fuel discharged from the fuel tank. A canister having an adsorbent that adsorbs the evaporative gas, a purge flow path that introduces the fuel evaporative gas discharged from the canister into a region adjacent to the inlet of the compressor in the intake flow path of the engine, and the purge flow path. A purge control valve that can switch between an open state that enables the introduction of fuel evaporative gas and a closed state that substantially blocks the purge flow path, and the air bypass valve when the purge control valve is in the open state. It is a fuel evaporative emission gas treatment apparatus including a control means for opening a state.
According to this, at the time of supercharging, the air bypass valve is opened to return a part of the air on the outlet side of the compressor to the inlet side to reduce the efficiency of the compressor, thereby increasing the work load of the compressor and the inlet of the compressor. The negative pressure generated in the part can be increased (pressure decreased).
By sucking the fuel evaporative gas from the canister by this negative pressure, the purge gas flow rate can be secured even at the time of supercharging, and the canister can be appropriately purged.
It should be noted that such an air bypass valve is usually provided in a general turbocharged engine for other purposes such as prevention of surging and blade protection, and it is necessary to add new parts. It is possible to simplify the structure.

The invention according to claim 2, before Symbol control unit, when the required torque is equal to or greater than a predetermined value, characterized in that the closed state of the air bypass valve regardless of the state of the purge control valve according Item 2. The fuel evaporative emission treatment apparatus according to item 1.
According to this, in the high load region where a relatively high supercharging pressure is required, the engine output and drivability are ensured by closing the air bypass valve and prioritizing the increase in supercharging pressure over purging the canister. can do.

The invention according to claim 3 includes a concentration estimation means for estimating the concentration of fuel evaporative gas released from the canister, and the control means controls the opening degree of the air bypass valve to control the opening degree of the air bypass valve to provide air in the bypass flow path. The first or second aspect of the invention, which has a function of changing the flow rate and reduces the air flow rate of the bypass flow path according to an increase in the concentration of the fuel evaporative gas estimated by the concentration estimation means. It is a fuel evaporative gas treatment device.
According to this, it is possible to prevent an excessively high concentration of fuel evaporative gas from being introduced excessively into the intake pipe of the engine and causing a rich misfire.

As described above, according to the present invention, it is possible to provide a fuel evaporative gas treatment apparatus capable of ensuring a purge gas flow rate even during supercharging with a simple configuration.

It is a figure which shows typically the structure of the engine which has Example 1 of the fuel evaporative gas processing apparatus to which this invention was applied. It is a flowchart which shows the operation at the time of a canister purge in the fuel exhaust gas processing apparatus of Example 1. It is a graph which shows typically the correlation between the engine intake air amount and the compressor inlet pressure in the fuel exhaust gas processing apparatus of Example 1. It is a graph which shows typically the correlation between the engine intake air amount and the purge gas flow rate in the fuel exhaust gas processing apparatus of Example 1. It is a graph which shows typically the correlation between the engine intake air amount and the compressor inlet pressure in Example 2 of the fuel exhaust gas processing apparatus to which this invention is applied. It is a graph which shows typically the correlation between the engine intake air amount and the purge gas flow rate in the fuel exhaust gas processing apparatus of Example 2.

The present invention solves the problem of providing a fuel evaporative gas treatment device capable of ensuring a purge gas flow rate even during supercharging with a simple configuration by returning a part of the intake air from the downstream side to the upstream side of the compressor of the turbocharger. The problem was solved by increasing the negative pressure at the inlet of the compressor and introducing purge gas using this negative pressure.

Hereinafter, examples of a fuel evaporative emission gas treatment apparatus to which the present invention is applied will be described.
The fuel evaporative gas treatment device of the embodiment is mounted on, for example, an automobile such as a passenger car equipped with a horizontally opposed 4-cylinder gasoline direct injection turbocharged engine as a power source for traveling.

FIG. 1 is a diagram schematically showing a configuration of an engine having the fuel evaporative gas treatment device of the first embodiment.
The engine 1 includes a crankshaft 10, a cylinder block 20, a cylinder head 30, a turbocharger 40, an intake system 50, an exhaust system 60, a canister 70, an engine control unit (ECU) 100, and the like.

The crankshaft 10 is a rotating shaft that serves as an output shaft of the engine 1.
A power transmission mechanism such as a transmission (not shown) is connected to one end of the crankshaft 10.
A piston is connected to the crankshaft 10 via a connecting rod (not shown).
At the end of the crankshaft 10, a crank angle sensor 11 for detecting the angular position of the crankshaft is provided.
The output of the crank angle sensor 11 is transmitted to the ECU 100.

The cylinder block 20 is configured as two parts so as to sandwich the crankshaft 10 from the left-right direction when it is vertically mounted on the vehicle body.
At the center of the cylinder block 20, a crankcase portion is provided that accommodates the crankshaft 10 and has a main bearing that rotatably supports the crankshaft 10.
Inside the left and right banks of the cylinder block 20 arranged on the left and right sides of the crankcase portion, for example, a pair of cylinders (in the case of four cylinders) in which a piston is inserted and reciprocates inside are formed.

The cylinder head 30 is provided at each end (left and right end) of the cylinder block 20 on the opposite side of the crankshaft 10.
The cylinder head 30 includes a combustion chamber 31, a spark plug 32, an intake port 33, an exhaust port 34, an intake valve 35, an exhaust valve 36, an intake camshaft 37, an exhaust camshaft 38, and the like.
The combustion chamber 31 is formed by denting a portion of the cylinder head 30 facing the piston crown surface, for example, in a pent roof shape.
The spark plug 32 is provided in the center of the combustion chamber 31 and generates a spark in response to an ignition signal from the ECU 100 to ignite the air-fuel mixture.

The intake port 33 is a flow path for introducing combustion air (fresh air) into the combustion chamber 31.
The exhaust port 34 is a flow path for discharging burned gas (exhaust gas) from the combustion chamber 31.
The intake valve 35 and the exhaust valve 36 open and close the intake port 33 and the exhaust valve 34 at predetermined valve timings.
For example, two intake valves 35 and two exhaust valves 36 are provided in each cylinder.
The intake valve 35 and the exhaust valve 36 are opened and closed by the intake camshaft 37 and the exhaust camshaft 38 that rotate synchronously at half the rotation speed of the crankshaft 10.
The cam sprocket portion of the intake camshaft 37 and the exhaust camshaft 38 is provided with a valve timing variable mechanism (not shown) that changes the valve opening timing and valve closing timing of each valve by advancing and retarding the phase of each camshaft. Has been done.

The turbocharger 40 is a supercharger that compresses and supercharges combustion air (fresh air) by utilizing the energy of the exhaust gas of the engine 1.
The turbocharger 40 includes a turbine 41, a compressor 42, an air bypass flow path 43, an air bypass valve 44, a wastegate flow path 45, a wastegate valve 46, and the like.
The turbine 41 is rotationally driven by the exhaust gas of the engine 1.
The compressor 42 is coaxially attached to the turbine 41 and is rotationally driven by the turbine 41 to compress air.

The air bypass flow path 43 extracts a part of air from the downstream side of the compressor 42 and returns it to the upstream side of the compressor 42.
The air bypass valve 44 is provided in the air bypass flow path 43, and is in a closed state in which the air bypass flow path 43 is substantially closed in response to a command from the ECU 100 and an open state in which air can pass through the air bypass flow path 43. And are switched in two stages.
The air bypass valve 44 is an electric valve having a valve body that is opened and closed by an electric actuator.
The air bypass valve 44 is opened to prevent surging of the turbocharger 40, protect the blades, and the like when the throttle valve 56 is suddenly closed, and the air in the intake pipe on the downstream side of the compressor 42 is opened. Is returned to the upstream side of the compressor 42 to reduce excess pressure.
Further, since the air bypass valve 44 increases the flow rate of the purge gas from the canister 70 during supercharging, it is also used to increase the negative pressure at the inlet of the compressor 42 in the open state during supercharging.
This point will be described in detail later.

The waistgate flow path 45 extracts a part of the exhaust gas from the upstream side of the turbine 41 and bypasses it to the downstream side of the turbine 41 for the purpose of controlling the boost pressure and raising the temperature of the catalyst.
The waistgate flow path 45 is integrally formed with the housing of the turbine 41.
The wastegate valve 46 has a valve body provided in the wastegate flow path 45 to open and close the flow path, and controls the flow rate of exhaust gas passing through the wastegate flow path 45.
The wastegate valve 46 is an electric wastegate valve having an electric actuator that opens and closes and drives the valve body in response to a command from the ECU 100.
The wastegate valve 46 can be switched between a fully open state and a fully closed state, and an arbitrary opening degree can be set even at an intermediate position between them.

The intake system 50 introduces air and introduces it into the intake port 33.
The intake system 50 includes an intake duct 51, a chamber 52, an air cleaner 53, an air flow meter 54, an intercooler 55, a throttle valve 56, an intake manifold 57, an intake pressure sensor 58, an injector 59, and the like.

The intake duct 51 is a flow path for introducing outside air into the intake port 33.
The chamber 52 is a space portion provided in communication with the vicinity of the entrance portion of the intake duct 51.
The air cleaner 53 is provided on the downstream side of the intake duct 51 at the communication point with the chamber 52, and filters air to remove dust and the like.
The air flow meter 54 is provided near the outlet of the air cleaner 53 and measures the flow rate of air passing through the intake duct 51.
The output of the air flow meter 54 is transmitted to the ECU 100.
The compressor 42 of the turbocharger 40 is provided on the downstream side of the air flow meter 54.

The intercooler 55 is provided on the downstream side of the compressor 42 in the intake duct 51, and is a heat exchanger that cools the compressed and high-temperature air by heat exchange with, for example, running wind.
The throttle valve 56 is a butterfly valve provided on the downstream side of the intercooler 55 in the intake duct 51 and controls the output of the engine 1 by adjusting the flow rate of air.
The throttle valve 56 is opened and closed by a throttle actuator (not shown) in response to an accelerator pedal operation (not shown) by the driver.
Further, the throttle valve 56 is provided with a throttle sensor for detecting the opening degree thereof, and its output is transmitted to the ECU 100.
The intake manifold 57 is a branch pipe provided on the downstream side of the throttle valve 56 and distributes air to the intake port 33 of each cylinder.
The intake pressure sensor 58 detects the pressure of air (intake pressure) in the intake manifold 57.
The output of the intake pressure sensor 58 is transmitted to the ECU 100.
The injector 59 is provided at the end of the intake manifold 57 on the cylinder head 30 side, and injects fuel into the combustion chamber 31 in response to a valve opening signal generated by the ECU 100 to form an air-fuel mixture.

The exhaust system 60 discharges the exhaust gas discharged from the exhaust port 34 to the outside.
The exhaust system 60 includes an exhaust manifold 61, an exhaust pipe 62, a front catalyst 63, a rear catalyst 64, a silencer 65, an air fuel ratio sensor 66, a rear O ₂ sensor 67, and the like.
The exhaust manifold 61 is a collecting pipe that collects the exhaust gas emitted from the exhaust port 34 of each cylinder.
The turbine 41 of the turbocharger 40 is arranged on the downstream side of the exhaust manifold 61.
The exhaust pipe 62 is a pipeline that discharges the exhaust gas emitted from the turbine 41 to the outside.
The front catalyst 63 and the rear catalyst 64 are provided in the intermediate portion of the exhaust pipe 62, and each includes a three-way catalyst that purifies HC, NOx, CO, etc. in the exhaust gas.
The front catalyst 63 is provided adjacent to the outlet of the turbine 41, and the rear catalyst 64 is provided on the outlet side of the front catalyst.
The silencer 65 is provided near the outlet of the exhaust pipe 62 to reduce the acoustic energy of the exhaust gas.

The air-fuel ratio sensor 66 is provided between the outlet of the turbine 41 and the inlet of the front catalyst 63.
The rear O ₂ sensor 67 is provided between the outlet of the front catalyst 63 and the inlet of the rear catalyst 64.
Both the air-fuel ratio sensor 66 and the rear O ₂ sensor 67 detect the amount of oxygen in the exhaust gas by generating an output voltage corresponding to the oxygen concentration in the exhaust gas.
The air-fuel ratio sensor 66 is a linear output sensor capable of detecting the oxygen concentration in a wider range of air-fuel ratios than the rear O ₂ sensor 67.
Air-fuel ratio sensor 66, the output of the rear _{O 2} sensor 67 is transmitted together ECU 100.

In the canister (charcoal canister) 70, fuel evaporative gas (evaporation) generated in a fuel tank (not shown) in which gasoline used as fuel for the engine 1 is stored is introduced and temporarily stored.
The canister 70 is configured by accommodating activated carbon capable of temporarily adsorbing fuel evaporative gas in a canister case which is a resin housing.

The canister 70 is mainly provided with a purge line 71 for non-supercharging, a purge control valve 72, a purge line 73 for supercharging, a purge control valve 74, and the like.

The purge line 71 is a flow path whose both ends are connected to the canister 70 and the intake manifold 57, respectively, and communicate between the insides thereof.
The purge line 71 introduces a purge gas made of fuel evaporative gas released from the canister 70 into the intake manifold 57 when the intake manifold 57 has a negative pressure during non-supercharging.
The purge control valve (PCV) 72 is a duty control solenoid valve provided in the middle of the purge line 71.
The PCV 72 can switch between the open state and the closed state and set the opening degree in the open state in response to a command from the ECU 100.

The purge line 73 is a flow path whose both ends are connected to the canister 70 and the region of the intake duct 51 adjacent to the inlet of the compressor 42 and communicate between the insides thereof.
The purge line 73 introduces the purge gas into the intake duct 51 on the upstream side of the compressor 42 at the time of supercharging where the pressure inside the intake manifold 57 becomes positive and it becomes difficult to introduce the purge gas by the purge line 71.
The purge control valve (PCV) 74 is a solenoid valve provided in the middle of the purge line 73.
The PCV 74 can switch between an open state and a closed state in response to a command from the ECU 100.
The control of the PCVs 72 and 74 described above will be described in detail later.

The engine control unit (ECU) 100 comprehensively controls the engine 1 and its accessories.
The ECU 100 is configured to include information processing means such as a CPU, storage means such as RAM and ROM, an input / output interface, and a bus connecting these.
Further, the ECU 100 is provided with an accelerator pedal sensor 101 that detects the amount of depression of the accelerator pedal (not shown) by the driver.
The ECU 100 has a function of setting the driver required torque based on the output of the accelerator pedal sensor 101 or the like.
The ECU 100 controls the throttle valve opening degree, boost pressure, fuel injection amount, ignition timing, valve timing, etc. so that the torque actually generated by the engine 1 approaches the set driver required torque.
Further, the ECU 100 functions as a control means according to the present invention, which controls the open / closed state of the air bypass valve 44 and the PCVs 72 and 74.

FIG. 2 is a flowchart showing an operation at the time of canister purging in the fuel exhaust gas treatment apparatus of the first embodiment.
Hereinafter, each step will be described step by step.

<Step S01: Judgment of engine operating state>
The ECU 100 determines the operating state of the engine 1 and determines whether or not a predetermined condition capable of executing purging of the canister 70 is satisfied.
As this condition, for example, the engine 1 is not in a stopped state or a fuel cut state, but in a complete explosion state in which the air-fuel mixture is normally and stably burned in the combustion chamber 31 of each cylinder for each cycle. Be done.
If the purge execution is possible, the process proceeds to step S02, and if the purge execution is not possible, a series of processes is completed (returned).

<Step S02: Judgment of intake manifold internal pressure>
The ECU 100 compares the pressure in the intake manifold 57 detected by the intake pressure sensor 58 (not shown) with a predetermined value (threshold value) set in advance, and if it is equal to or more than a predetermined value, supercharges the pressure in the intake manifold 57. It is judged that the negative pressure is small or the positive pressure is equal to or higher than the atmospheric pressure, and it is difficult to introduce the purge gas by the purge line 71.
If the pressure in the intake manifold 57 is equal to or higher than a predetermined value, the process proceeds to step S03, and in other cases, the process proceeds to step S04.

<Step S03: Open PCV for supercharging>
The ECU 100 keeps the supercharged PCV74 in the open state and the non-supercharged PCV72 in the closed state.
After that, the process proceeds to step S05.

<Step S04: PCV open for non-supercharging>
The ECU 100 opens the non-supercharged PCV 72 and closes the supercharged PCV 74.
After that, a series of processing is completed (returned).

<Step S05: Judgment of driver required torque>
The ECU 100 determines whether or not the current driver required torque is equal to or higher than a predetermined value which is a preset threshold value.
When the driver required torque is equal to or higher than a predetermined value, it is considered that the output and drivability should be prioritized over the purge gas flow rate, and a series of processing is completed (return) with the air bypass valve 44 closed. To do.
On the other hand, if the driver required torque is less than a predetermined value, the process proceeds to step S06 in order to increase the purge gas flow rate.

<Step S06: Open air bypass valve>
The ECU 100 opens the air bypass valve 44 and returns a part of the air on the outlet side of the compressor 42 to the inlet side via the bypass flow path 43.
As a result, the efficiency of the compressor 42 can be lowered, the negative pressure at the inlet of the compressor 42 can be increased (the pressure can be lowered), and the purge gas flow rate of the purge line 73 can be increased.
After that, a series of processing is completed (returned).

Hereinafter, the effect of Example 1 will be described.
FIG. 3 is a graph schematically showing the correlation between the engine intake air amount and the compressor inlet pressure in the fuel exhaust gas treatment apparatus of the first embodiment.
In FIG. 3, the horizontal axis represents the amount of intake air from the engine, and the vertical axis represents the pressure in the intake duct 51 near the inlet of the compressor 42. (Same in FIG. 5)
In FIG. 3, the correlation in the first embodiment is shown by a solid line, and the correlation when the air bypass valve 44 is always in the fully closed state is shown by a chain double-dashed line. (Same in FIGS. 4 to 6)
FIG. 4 is a graph schematically showing the correlation between the engine intake air amount and the purge gas flow rate in the fuel exhaust gas treatment apparatus of the first embodiment.
In FIG. 4, the horizontal axis represents the amount of intake air for the engine, and the vertical axis represents the flow rate of the purge gas (fuel evaporative gas) in the purge line 73. (Same in FIG. 6)
The engine intake air amount increases as the driver required torque set by the ECU 100 increases.
Further, since the boost pressure of the engine 1 increases as the amount of intake air for the engine increases, the tendency is substantially the same even when the boost pressure is taken as the horizontal axis.

In the first embodiment, in the region where the driver required torque set by the ECU 100 is low and the engine intake air amount is equal to or less than a predetermined value, the efficiency of the compressor 42 is lowered by opening the air bypass valve 44, and the inlet of the compressor 42 is introduced. The negative pressure in the part can be increased (pressure decreased).
As a result, it can be seen that the suction of the purge gas is promoted and the flow rate of the purge gas is also increased as shown in FIG.
On the other hand, in a high load region where the driver required torque is large and the engine intake air amount exceeds a predetermined value, the efficiency of the compressor 42 is improved by closing the air bypass valve 44 to ensure the output and drivability of the engine 1. can do.

As described above, according to the first embodiment, the following effects can be obtained.
(1) At the time of supercharging, the air bypass valve 44 is opened to return a part of the air on the outlet side of the compressor 42 to the inlet side to reduce the efficiency of the compressor 42, thereby increasing the work load of the compressor 42 and increasing the work load of the compressor 42. The negative pressure generated at the inlet can be increased (pressure decreased).
By sucking the purge gas composed of fuel evaporative gas from the canister 70 through the purge line 73 for supercharging by this negative pressure, the purge gas flow rate is secured even during supercharging and the canister 70 is properly purged. It can be carried out.
(2) In a high load region such as when fully open, which requires a relatively high boost pressure, the boost pressure rise of the engine 1 is prioritized over the purge of the canister 70 by closing the air bypass valve 44. Output and drivability can be ensured.
(3) Since the air bypass valve 44 can be shared with the so-called blow-off valve usually provided in a general turbocharged engine for the purpose of discharging excess pressure on the downstream side of the compressor 42, for purging gas treatment. It is not necessary to newly add to the device, and the configuration of the device can be simplified.

Next, Example 2 of the fuel exhaust gas treatment apparatus to which the present invention is applied will be described.
The parts substantially in common with the above-described first embodiment are designated by the same reference numerals and the description thereof will be omitted, and the differences will be mainly described.
In the second embodiment, as the air bypass valve 44, a valve capable of continuously changing the air flow rate of the bypass flow path 43 by, for example, a duty-controlled solenoid valve or the like is used.

FIG. 5 is a graph schematically showing the correlation between the engine intake air amount and the compressor inlet pressure in the fuel exhaust gas treatment apparatus of the second embodiment.
FIG. 6 is a graph schematically showing the correlation between the engine intake air amount and the purge gas flow rate in the fuel exhaust gas treatment apparatus of the second embodiment.
As shown in FIGS. 5 and 6, in the second embodiment, the air bypass valve 44 is opened in a region where the engine intake air amount is larger than a predetermined value (the value for switching the opening and closing of the air bypass valve 44 in the first embodiment). The degree is continuously changed from the fully open state so as to be in the fully closed state in the fully open (fully loaded) region according to the increase in the engine intake air amount.

Further, in the second embodiment, a known concentration estimation means for estimating the concentration of the fuel evaporative gas (evaporator) released from the canister 70 is provided, and when the estimated concentration is equal to or higher than a predetermined value, the engine 1 is provided. In order to prevent rich misfire, the opening degree of the air bypass valve 44 at the time of supercharging is set to decrease as the evaporation concentration increases, and control is performed to limit the flow rate of the purge gas.

According to the second embodiment described above, in addition to the effect substantially similar to the effect of the first embodiment described above, the purge gas flow rate is precisely controlled by utilizing the intermediate opening degree of the air bypass valve 44. , More appropriate treatment of fuel evaporative gas can be performed.

(Modification example)
The present invention is not limited to the examples described above, and various modifications and modifications can be made, and these are also within the technical scope of the present invention.
For example, the configurations of the engine and the fuel evaporative gas treatment device are not limited to the configurations of the above-described embodiment, and can be appropriately changed.
For example, the cylinder layout of the engine, the number of cylinders, the number of turbochargers, and the like are not limited to the above-described embodiment and can be appropriately changed.
Further, although the engine of the embodiment uses gasoline as the fuel, it is not limited to gasoline and can be changed as appropriate as long as it is a volatile fuel that can be occluded by a canister and purged using the negative pressure of the intake pipe. Is.

1 Engine 10 Crankshaft 11 Crank angle sensor 20 Cylinder block 30 Cylinder head 31 Combustion chamber 32 Ignition plug 33 Intake port 34 Exhaust port 35 Intake valve 36 Exhaust valve 37 Intake cam shaft 38 Exhaust cam shaft 40 Turbocharger 41 Turbine 42 Compressor 43 Air Bypass flow path 44 Air bypass valve 45 Westgate flow path 46 Westgate valve 50 Intake system 51 Intake duct 52 Chamber 53 Air cleaner 54 Air flow meter 55 Intercooler 56 Throttle valve 57 Intake manifold 58 Intake pressure sensor 59 Injector 60 Exhaust manifold 62 Exhaust pipe 63 Front catalyst 64 Rear catalyst 65 Silencer 66 Air fuel ratio sensor 67 Rear O ₂ sensor 70 Canister 71 Purge line 72 Purge control valve 73 Purge line 74 Purge control valve 100 Engine control unit (ECU)
101 Accelerator pedal sensor

Claims (3)

The required torque setting means for setting the required torque of the engine and the required torque setting means
The compressor for compressing is driven by the turbine and the turbine driven by the exhaust air possess a turbocharger boost pressure is controlled so that the torque generated by the engine approaches the required torque,
A bypass flow path that extracts a part of air from the outlet side of the compressor and returns it to the inlet side of the compressor.
A fuel evaporative gas treatment device provided in an engine provided with an air bypass valve that can switch between an open state that enables air to return through the bypass flow path and a closed state that substantially closes the bypass flow path. ,
A canister with an adsorbent that adsorbs the fuel evaporative gas discharged from the fuel tank,
A purge flow path that introduces the fuel evaporative gas released from the canister into a region adjacent to the inlet of the compressor in the intake flow path of the engine.
A purge control valve that can switch between an open state that enables the introduction of fuel evaporative gas through the purge flow path and a closed state that substantially blocks the purge flow path.
A fuel evaporative gas treatment apparatus comprising: a control means for opening the air bypass valve when the purge control valve is in the open state. Before SL control means, fuel evaporative emission according to claim 1 wherein the required torque in the case where more than the predetermined value, characterized in that the closed state of the air bypass valve regardless of the state of the purge control valve Processing equipment. A concentration estimation means for estimating the concentration of the fuel evaporative gas emitted from the canister is provided.
The control means has a function of controlling the opening degree of the air bypass valve to change the air flow rate of the bypass flow path, and the bypass flow according to an increase in the concentration of fuel evaporative gas estimated by the concentration estimation means. The fuel evaporative gas treatment apparatus according to claim 1 or 2, wherein the air flow rate of the road is reduced.

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