JP3322004B2 - Engine fuel gas treatment system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for treating fuel evaporative gas of an engine.

[0002]

2. Description of the Related Art A conventional fuel evaporative gas processing apparatus for an engine includes a canister for temporarily adsorbing fuel evaporative gas in a fuel tank, and a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of the engine. Are provided to prevent the emission of the fuel evaporative gas into the atmosphere.

However, when the fuel evaporative gas is introduced into the intake pipe of the engine, the air-fuel ratio fluctuates.
It is necessary to correct the fuel supply amount to the engine by the supplied evaporated fuel amount. For this reason, conventionally, O ₂
By comparing the actual air-fuel ratio detected from the residual oxygen amount in the exhaust gas after the combustion with the sensor with the air-fuel ratio determined according to the operating conditions of the engine, the amount of the supplied fuel vapor is estimated. The fuel supply amount is corrected.

[0004] However, in the method of estimating the amount of fuel vapor from the exhaust gas after combustion by the O ₂ sensor, it is difficult to cope with the transient state because a delay occurs in the control. Further, at low temperatures, since the O ₂ sensor is inactive, it is impossible to estimate the amount of evaporated fuel itself. Therefore, as shown in Japanese Patent Application Laid-Open No. 3-249673, a flow meter for measuring the flow rate of the fuel evaporative gas from the fuel tank to the canister, and a fuel temperature sensor for detecting the temperature of the fuel in the fuel tank are provided. In some cases, the amount of fuel supplied to the engine is corrected according to the flow rate and temperature of the fuel evaporative gas.

[0005]

However, in the apparatus described in the above publication, it is impossible to accurately know the concentration of fuel in the fuel evaporative gas. Therefore, the fuel supply amount of the engine is corrected based on the measured flow rate. However, there is a problem that the final air-fuel ratio may fluctuate. In view of such circumstances, an object of the present invention is to improve the control accuracy of the air-fuel ratio by knowing the concentration of the fuel in the fuel evaporative gas supplied to the engine.

Accordingly, assuming that the control accuracy of the air-fuel ratio is improved, the proportion of the fuel evaporative gas to the fuel supply amount during warm-up immediately after the start of the engine is increased to improve the stability of combustion and the like. The purpose is to improve. It is another object of the present invention to cope with the case where the fuel evaporative gas is liquefied in the purge passage and to ensure the stability of combustion and the like.

Another object of the present invention is to make it difficult to evenly distribute the fuel evaporative gas to all the cylinders, which causes the air-fuel ratio to vary among the cylinders. It is another object of the present invention to measure the concentration of the fuel in the fuel evaporative gas with higher accuracy.

Another object of the present invention is to reduce the load on the canister by directly supplying the fuel to the engine without introducing the fuel into the canister when the concentration of fuel in the fuel vapor from the fuel tank is high. And

[0009]

According to a first aspect of the present invention, there is provided a canister for temporarily adsorbing fuel evaporative gas in a fuel tank, and a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of an engine. Irradiating the fuel vapor gas in the purge passage with an infrared laser beam, and detecting the air fuel ratio of the fuel vapor gas based on the rate at which the fuel vapor gas absorbs the infrared laser beam. Means, correction means for reducing the amount of fuel supplied to the engine based on the detected air-fuel ratio of the fuel evaporative gas, and fuel supply for supplying a fuel amount corresponding to the output of the correction means to the intake pipe of the engine. Means are provided to constitute a fuel-evaporated-gas processing device for an engine.

In the second invention, a canister for temporarily adsorbing the fuel evaporative gas in the fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of the engine, and a bypass for bypassing the canister. A bypass passage for guiding the fuel evaporative gas in the fuel tank to the middle of the purge passage; and a switch between introduction of the fuel evaporative gas in the fuel tank into the canister and introduction into the bypass passage. A switching valve for introducing fuel evaporative gas in the canister to the canister when the engine is stopped, and for introducing the fuel evaporative gas to the bypass passage during operation including engine start-up, and the purge passage upstream of a connection position of the bypass passage. And an on-off valve that opens until warm-up is completed when the engine is started, and a fuel vapor in the purge passage downstream of a connection position of the bypass passage. Irradiated with infrared laser light to the gas, the fuel evaporation gas is based on the rate at which absorb the infrared laser beam,
Fuel evaporative gas air-fuel ratio detecting means for detecting the air-fuel ratio of the fuel evaporative gas, correcting means for reducing the amount of fuel supplied to the engine based on the detected air-fuel ratio of the fuel evaporative gas, and output of the correcting means And a fuel supply means for supplying a fuel amount according to the above to the intake pipe of the engine to constitute a fuel vapor processing apparatus for the engine.

In the third aspect, the canister for temporarily adsorbing the fuel evaporative gas in the fuel tank, the purge passage for guiding the fuel evaporative gas adsorbed by the canister to the intake pipe of the engine, and the exhaust gas from the engine are provided. An exhaust gas recirculation device capable of being recirculated to the purge passage via a switching valve; gas-liquid state determination means for determining a gas-liquid state of the fuel in the purge passage; When in a liquid phase state, the switching valve of the exhaust gas recirculation device is switched to recirculate exhaust gas into the purge passage, and vaporize means for vaporizing fuel in the purge passage. Irradiating an infrared laser beam, based on a rate at which the fuel vapor gas absorbs the infrared laser beam, a fuel evaporative gas air-fuel ratio detecting means for detecting an air-fuel ratio of the fuel evaporative gas,
Correction means for reducing the amount of fuel supplied to the engine based on the detected air-fuel ratio of the fuel evaporative gas, and fuel supply means for supplying a fuel amount corresponding to the output of the correction means to the intake pipe of the engine. The fuel evaporative gas treatment device of the engine is provided.

According to a fourth aspect of the present invention, a fuel-evaporated gas processing apparatus for a multi-cylinder engine having a plurality of cylinders and a plurality of fuel supply means for supplying fuel to intake pipes corresponding to the respective cylinders is provided. A canister for temporarily adsorbing the fuel evaporative gas in the fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of a specific one cylinder of the engine; A fuel evaporative gas air-fuel ratio detecting means for irradiating the infrared laser light and detecting an air-fuel ratio of the fuel evaporative gas based on a rate at which the fuel evaporative gas absorbs the infrared laser light; Correction means for reducing the amount of fuel supplied to the specific one cylinder of the engine by the fuel supply means based on the air-fuel ratio is provided to constitute a fuel evaporative gas processing apparatus for the engine.

In the fifth aspect, the canister for temporarily adsorbing the fuel evaporative gas in the fuel tank, the purge passage for guiding the fuel evaporative gas adsorbed by the canister to the intake pipe of the engine, A secondary air supply device for supplying secondary air, and irradiating the fuel evaporative gas in the purge passage with an infrared laser beam, based on a rate at which the fuel evaporative gas absorbs the infrared laser light. Fuel evaporative gas air-fuel ratio detecting means for detecting the air-fuel ratio, correcting means for reducing the amount of fuel supplied to the engine based on the detected air-fuel ratio of the fuel evaporative gas, and fuel corresponding to the output of the correcting means Fuel supply means for supplying the amount to the intake pipe of the engine, and based on the air-fuel ratio of the fuel evaporative gas detected by the fuel evaporative gas air-fuel ratio detecting means, such that the air-fuel ratio falls within a predetermined range. It provided the secondary air supply amount control means for controlling the supply amount of the secondary air by serial secondary air supply system, a fuel vapor treatment system for an engine.

In the sixth aspect, the canister for temporarily adsorbing the fuel evaporative gas in the fuel tank, the purge passage for guiding the fuel evaporative gas adsorbed by the canister to the intake pipe of the engine, and the purge passage are disposed in the purge passage. A first control valve, a bypass passage that bypasses the canister and the first control valve and guides fuel evaporative gas in a fuel tank to an intake pipe of an engine, and a first control valve that is disposed in the bypass passage. 2
A control valve, and irradiating the fuel vapor gas in the purge passage upstream of the first control valve with an infrared laser beam, based on a rate at which the fuel vapor gas absorbs the infrared laser beam. A first fuel evaporative gas air-fuel ratio detecting means for detecting an air-fuel ratio of the fuel evaporative gas, and irradiating the fuel evaporative gas in the bypass passage upstream of the second control valve with an infrared laser beam. Based on the rate of absorbing this infrared laser light,
Second fuel evaporative gas air-fuel ratio detecting means for detecting the air-fuel ratio of the fuel evaporative gas in the bypass passage; and air-fuel ratio of the fuel evaporative gas detected by the first and second fuel evaporative gas air-fuel ratio detecting means. And based on the result of the comparison,
Of the first and second control valves, the control valve in the passage on the side where the air-fuel ratio of the fuel evaporative gas is rich is opened ,
Control valve control means for closing the control valve in the passage with the lower ratio , and fuel to be supplied to the engine based on the detected air-fuel ratio of the fuel evaporative gas in the passage in which the control valve is opened. A correction means for reducing the amount and a fuel supply means for supplying a fuel amount corresponding to an output of the correction means to an intake pipe of the engine are provided to constitute a fuel evaporative gas processing device of the engine.

[0015]

According to the first aspect, the air-fuel ratio (fuel concentration) of the fuel evaporative gas can be directly detected from the absorptance of the infrared laser light, thereby correcting the amount of fuel supplied from the fuel supply means. Thus, the control accuracy of the overall air-fuel ratio is improved.
In the second aspect of the present invention, the fuel evaporative gas in the fuel tank is introduced into the canister by the switching valve while the engine is stopped, and is adsorbed and held by the canister. During the operation including the start of the engine, the fuel evaporative gas in the fuel tank is supplied to the canister. It is supplied directly to the intake pipe without introduction. During the warm-up immediately after the start of the engine operation, the on-off valve is opened to supply the fuel vapor adsorbed and held in the canister to the intake pipe.

As described above, when the engine is started, the fuel evaporative gas from both the fuel tank and the canister is supplied to the intake pipe until the warm-up is completed, so that the ratio of the fuel evaporative gas to the entire fuel supply amount can be increased. In general, before the engine has been warmed up, that is, when the engine is cold, fuel wall flow is likely to occur, resulting in poor combustion stability and exhaust emissions. By reducing the amount of fuel supplied from the injection valve or the like, the stability of combustion and the emission of exhaust can be improved.

In addition, since the air-fuel ratio of the fuel evaporative gas is detected by the infrared laser light, the overall air-fuel ratio does not deviate from the target value, and even before the completion of the warm-up, the fuel evaporative gas is detected. Purging can be performed. Third
According to the invention, when the fuel evaporative gas is liquefied in the purge passage, not only combustion deteriorates, but also it becomes difficult to accurately measure the air-fuel ratio even by infrared laser light. When the exhaust gas is recirculated, high-temperature exhaust gas is introduced into the purge passage to vaporize the liquefied fuel, ensure combustion stability, and detect the air-fuel ratio of the combustion evaporative gas. The processing of the fuel evaporative gas is performed.

When the gas-liquid state of the fuel in the purge passage is determined, the absorption rate of the liquefied fuel for the infrared laser light becomes very large. The used fuel evaporative gas air-fuel ratio detecting means can be used. According to the fourth aspect of the invention, the fuel-evaporated gas is concentrated in one specific cylinder, so that the air-fuel ratio can be prevented from shifting between the cylinders. In other words, the air-fuel ratio of the fuel evaporative gas can be accurately obtained from the absorptance of the infrared laser light, and the fuel supply amount can be corrected. Therefore, the fuel evaporative gas can be concentrated in one cylinder. .

In the fifth aspect of the present invention, since the measurement of the air-fuel ratio by the infrared laser beam has a measurable range, a secondary air supply device for supplying secondary air to the purge passage is provided, and the inside of the purge passage is provided. The amount of secondary air supplied by the secondary air supply device is controlled so that the air-fuel ratio of the fuel evaporative gas falls within a predetermined range. In this case, by introducing and diluting secondary air, the air-fuel ratio of the fuel evaporative gas is always kept within the measurement range, enabling accurate measurement, and further improving the control accuracy of the air-fuel ratio of the engine. improves.

In the sixth aspect, the air-fuel ratio of the fuel evaporative gas in the purge passage (the air-fuel ratio of the fuel evaporative gas from the canister) and the air-fuel ratio of the fuel evaporative gas in the bypass passage (the fuel evaporative gas from the fuel tank) At the same time, and when the air-fuel ratio of the fuel evaporative gas from the fuel tank is higher than the air-fuel ratio of the fuel evaporative gas from the canister, the fuel evaporative gas from the fuel tank is directly supplied to the engine. By leading the canister, the burden on the canister is reduced.

[0021]

Embodiments of the present invention will be described below. FIG. 1 shows an embodiment corresponding to the first and second inventions. The air taken from the air cleaner 2 is controlled by the throttle valve 3 and is introduced into the engine 1 from the intake pipe 4.
The intake pipe 4 is provided with a fuel injection valve 5 as a fuel supply means for each cylinder.

The fuel injection valve 5 includes a control unit 6
The valve is opened by a drive pulse signal output at a predetermined timing in synchronism with the engine rotation, and fuel is injected during the valve opening period. Signals from various sensors are input to the control unit 6 for controlling the fuel injection amount. The various sensors include an intake pressure sensor 7 for detecting an intake pressure (absolute pressure) Pa in the intake pipe 4 and an intake pipe 4.
An intake air temperature sensor 8 for detecting an intake air temperature Ta, an engine speed sensor 9 for detecting an engine speed N, a cooling water temperature sensor 10 for detecting a cooling water temperature Tw, and a three-way catalyst for an exhaust pipe 11.
An O ₂ sensor 13 and the like arranged upstream of 12 are provided.

Further, in order to process the fuel evaporative gas generated in the fuel tank 14, the upper space of the fuel tank 14 is provided with a passage 16 (16a, 16a) through a fuel check valve (check valve) 15.
b) is connected to the canister 17. The canister 17 has a built-in activated carbon, and thereby adsorbs and holds the fuel evaporative gas from the fuel tank 14. The canister 17 is also provided with a purge air inlet 18 and one end of a purge passage 19 (19a, 19b) is connected. The other end of the purge passage 19 is connected to a purge port provided in the intake pipe 4.
Connected to 20. As a result, the fuel adsorbed by the canister 17 is released by the air introduced from the purge air inlet 18 and is supplied into the intake pipe 4 from the purge passage 19 (19a, 19b).

Also, the canister 17 is bypassed to
16 (16a, 16b) and the purge passage 19 (19a, 19b).
A bypass passage 21 is provided to communicate with the middle of b). An electromagnetic switching valve 22 is provided at a connection between the passages 16a and 16b and the bypass passage 21. This electromagnetic switching valve 22
Is a passage 16a on the fuel tank 14 side at one position (OFF position).
Is connected to the passage 16b on the canister 17 side, and the passage 16a on the fuel tank 14 side is connected to the bypass passage 21 at another position (ON position). The operation of the electromagnetic switching valve 22 is controlled by the control unit 6. When the engine is stopped, the passage 16a on the fuel tank 14 side is connected to the passage 16b on the canister 17 side. The side passage 16a is switched to connect to the bypass passage 21.

An electromagnetic on-off valve 23 is provided in the purge passage 19a on the upstream side of the connection of the bypass passage 21. The operation of the on-off valve 23 is also controlled by the control unit 6, and is turned on until the warm-up is completed when the engine is started, so that the valve is opened. Further, a fuel evaporative gas air-fuel ratio detecting means is provided in the purge passage 19b downstream (preferably near the purge port 20) from the connection portion of the bypass passage 21.

As shown in an enlarged view in FIG. 2, transparent glass windows 24a and 24b made of quartz or sapphire are provided on the passage wall of the purge passage 19b so that infrared laser light can cross the passage. , by relatively to one of the transparent glass window 24a, the laser oscillator 25 is provided, are to be irradiated with the infrared laser beam L ₁ to the fuel evaporative emission in the passage by the laser oscillator 25. Also, relative to the other transparent glass window 24b,
The photoelectric conversion element 26 for receiving the laser beam L ₂ after having traversed the passageway is provided, are input a signal of the photoelectric conversion element 26 to the control unit 6.

[0027] That is, when irradiated with infrared laser light L ₁ to the fuel evaporation gas in the purge passage 19 by the laser oscillator 25, the laser light is absorbed in accordance with the concentration of fuel vapor in the purge passage 19, out without being absorbed the laser beam L ₂ have enters the photoelectric conversion element 26 is converted into an electrical signal. Therefore,
An electric signal having an output corresponding to the air-fuel ratio (evaporated fuel concentration) of the fuel evaporative gas is input to the control unit 6.

Next, the operation will be described with reference to the flowchart of FIG. 3 showing the flow of control executed by the control unit 6. In step 1 (shown as S1 in the figure; the same applies hereinafter), it is determined whether or not the engine is stopped (engine key switch is turned off). If YES, the process proceeds to step 2 and the electromagnetic switching valve 22 is turned off ( Canister 17
(Selected state) and the electromagnetic on-off valve 23 is turned off (closed).

That is, when the engine is stopped, a large amount of fuel vapor is generated from the fuel tank 14. Therefore, at this time, as shown in FIG. 4A, the electromagnetic switching valve 22 connects the passage 16a on the fuel tank 14 side to the passage 16b on the canister 17 side, guides the fuel evaporative gas to the canister 17, and activates the activated carbon. To be absorbed. Then, the solenoid on-off valve 23 on the outlet side of the canister 17 closes the purge passage 19 so as not to conduct.

If the engine is not stopped, warm-up is completed (water temperature Tw) based on a signal from the water temperature sensor 10 in step 3.
Is greater than or equal to a predetermined value), and if NO (before the completion of warm-up), the routine proceeds to step 4 where the electromagnetic switching valve 22 is turned on (bypass passage 21 is selected) and the electromagnetic switching valve 23 Is turned ON (valve opening), and the process proceeds to step 6 and subsequent steps. That is, before the completion of warm-up, including when the engine is started, FIG.
As shown in FIG. 3, the electromagnetic switching valve 22 is connected to the passage 16 on the fuel tank 14 side.
a is connected to the bypass passage 21, and the fuel evaporative gas is directly supplied to the intake pipe 4 without leading to the canister 16. Further, the electromagnetic on-off valve 23 is opened to supply the fuel vapor adsorbed by the canister 17 to the intake pipe 4 while the engine is stopped. Thus, when the engine is started, a large amount of both the fuel evaporative gas in the fuel tank 14 and the evaporative fuel gas adsorbed by the canister 17 are purged to the intake pipe 4 until the warm-up is completed. Accordingly, by reducing the fuel injection amount from the fuel injection valve 5 as will be described later, the ratio of the fuel evaporative gas to the entire fuel supply amount can be increased, whereby the fuel is unlikely to become a wall flow, and The stability of
Unburned HC can be reduced to improve exhaust emissions.

If the determination in step 3 is YES (after warm-up is completed), the routine proceeds to step 5, where the electromagnetic switching valve 22 is turned off.
N (bypass passage 21 is selected) and the electromagnetic on-off valve 23 is turned off (closed). That is, after the completion of the warm-up, as shown in FIG. 4C, the electromagnetic switching valve 22 continues to connect the passage 16a on the fuel tank 14 side to the bypass passage 21, but the electromagnetic on-off valve 23 closes.
Purging from the canister 17 is stopped. Therefore, the fuel evaporative gas generated from the fuel tank 14 is supplied to the intake pipe 4 through the purge passage 19 as it is. By doing so, the load of the activated carbon on the canister 17 can be reduced, and the life can be prolonged. Further, even if the fuel evaporative gas is directly and continuously supplied, the air-fuel ratio is controlled by reducing the fuel injection amount from the fuel injection valve 5 as described later, so that the air-fuel ratio in the engine combustion chamber is controlled. Fluctuation can be prevented, and the fuel injection amount can be reduced, so that fuel efficiency can be improved.

In and after step 6, the fuel injection amount from the fuel injection valve 5 is corrected. In step 6, the intake pressure Pa is read based on the signal from the intake pressure sensor 7, in step 7, the intake temperature Ta is read based on the signal from the intake temperature sensor 8, and in step 8, the intake pressure Pa and the intake temperature Ta are calculated. The intake air amount Q is calculated based on the calculated amount. In step 9, a fuel amount Ft for obtaining the target A / F is calculated based on the intake air amount Q and the engine speed N.

In step 10, the air-fuel ratio of the fuel vapor in the purge passage 19 (purge passage A / F) is read based on the signal from the photoelectric conversion element 26. In step 11, the intake pressure P
The intake volume Vp of the gas to be purged into the intake pipe 4 is calculated based on a and the intake temperature Ta. Inlet pipe 4 from purge passage 19
The amount of gas introduced into the air passage depends on the negative pressure of the intake pipe 4 and the purge passage 19.
Is taken into the intake pipe 4 during the time when the suction is performed and the suction negative pressure is generated, and the volume can be determined by performing the time integration.

In step 12, the amount of fuel Fp purged from the purge gas suction volume Vp and the purge passage A / F is calculated. Then, in step 13, the fuel injection amount Fi = Ft-Fp by the fuel injection valve 5 is calculated by subtracting the purge fuel amount Fp from the target A / F fuel amount Ft. This part corresponds to the correction means.

When the fuel injection amount Fi is calculated, a drive pulse signal having a pulse width corresponding to the calculated fuel injection amount Fi is output to the fuel injection valve 5 at a predetermined timing in synchronization with the engine rotation, and fuel injection is performed. As described above, the air-fuel ratio (fuel concentration) of the fuel evaporative gas is directly detected from the absorption rate of the infrared laser light, and the amount of fuel to be purged is calculated based on the detected air-fuel ratio. , The control accuracy of the overall air-fuel ratio is greatly improved. Further, since the air-fuel ratio can be adjusted before combustion, the response until the target air-fuel ratio is set is fast, and it is possible to cope with a transient without delay.

FIG. 5 shows an embodiment corresponding to the third invention. In this embodiment, components are added to the embodiment shown in FIG. 1, and this will be described below. That is, the exhaust gas from the engine 1 is extracted from the exhaust gas outlet 31 of the exhaust pipe 11 and is connected to the intake pipe 4 by the exhaust gas recirculation port 32.
An exhaust gas recirculation device 33 is provided, which recirculates the exhaust gas from the engine 1 through an electromagnetic switching valve 34 to a purge passage 19 through another exhaust gas recirculation port 35.
Can be refluxed.

The reason for this is that the state of the fuel supplied from the purge passage 19 is not limited to the gasified state, but may flow in a liquid state depending on the state of the engine. For example, the gaseous fuel in the purge passage 19 may be cooled and liquefied by leaving the vehicle overnight, and may become liquid when the engine is restarted. In order to prevent this inflow, the gas-liquid state of the fuel in the purge passage 19 is determined, and based on the determination result, when the fuel in the purge passage 19 is in the liquid state, the switching valve of the exhaust gas recirculation device 33 is determined. It is necessary to switch 34 so that the exhaust gas is recirculated in the purge passage 19, thereby vaporizing the fuel in the purge passage 19.

First, the gas-liquid state of the fuel is determined by using an infrared laser type fuel evaporative gas air-fuel ratio detecting means. As shown in FIG. 6, the purge passage 19 of the detecting section is disposed horizontally. On the other hand, the optical path of the infrared laser light is arranged in the vertical direction. In this case, since the fuel, particularly gasoline fuel, has a very low viscosity, it always flows through the bottom surface in a pipe having a certain length such as the purge passage 19. Therefore, by arranging the optical path of the infrared laser light vertically, the liquid fuel can surely pass through the optical path.

Since the light absorptivity depends on the density of the substance, the absorptivity differs by several orders of magnitude between a fuel in a liquid phase and a gaseous fuel. Therefore, the fuel state can be determined from the transmitted light intensity obtained as the output of the photoelectric conversion element 26. Specifically, as shown in FIG. 7, when the transmitted light intensity is significantly reduced to a predetermined level or less, it is determined that the fuel in the liquid phase is passing through the optical path of the infrared laser light.

If the fuel in the purge passage 19 is in a liquid phase, there is a problem in its distribution and responsiveness, and it is necessary to vaporize the fuel. As the vaporizing means, heat of the exhaust gas recirculation gas is used. That is, as shown in the flowchart of FIG. 8, the signal of the photoelectric conversion element 26 is read in step 21 and it is determined in step 22 whether or not the fuel is liquid based on the signal. Solenoid switching valve
While the exhaust gas is recirculated from the normal exhaust gas recirculation port 32 while the exhaust gas is recirculated, the electromagnetic switching valve 34 is turned on in step 24, and the exhaust gas enters the purge passage 19 from another exhaust gas recirculation port 35. Bring to reflux.

It is conceivable that the exhaust gas is always recirculated into the purge passage 19. However, in this case, the purge system must be made expensive with excellent temperature characteristics. Only when fuel is detected, the switching valve 34 switches the exhaust gas recirculation port. Therefore, even when the fuel is liquefied in the purge passage 19, the fuel is vaporized by the heat of the exhaust gas recirculation gas, so that the generation of unburned HC can be suppressed. Further, since the fuel is vaporized by the heat of the exhaust gas recirculation gas, the air-fuel ratio can always be measured in a gas state, and the control accuracy of the air-fuel ratio is improved.

FIG. 9 shows an embodiment corresponding to the fourth invention. In the embodiment of FIG. 9, the same elements as those of the embodiment of FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. The engine 1 is a four-cylinder engine, and the purge port 20 at the end of the purge passage 19 from the canister 17 is provided only in one cylinder (# 4 cylinder in this example) so that the fuel evaporative gas is supplied only to # 4 cylinder. It is.

In connection with this, the injection signal lines for the fuel injection valves 5 of the # 4 cylinder are made independent of the injection signal lines for the fuel injection valves 5 of the other # 1 to # 3 cylinders. An electromagnetic opening / closing valve 40 is provided in the middle of the purge passage 19 and is opened and closed by the control unit 6.

Further, as shown in FIG. 10, the position of the purge port 20 to the intake pipe 4 of the purge cylinder is such that the fuel injected from the fuel injection valve 5 of the purge cylinder is not sprayed, and the injected fuel is If a wall flow occurs in the intake pipe 4, this position is set so as not to enter. Next, the operation will be described. Conventionally, when fuel evaporative gas is generally supplied to the intake system, even if an attempt is made to uniformly distribute the gas to each cylinder, due to the arrangement of the intake pipes, the distribution is not always the same in each cylinder, and the air-fuel ratio in each cylinder is delicate. , The emission will deteriorate if cycle fluctuations occur or the concentration is too high.

Therefore, it is assumed that the cylinder to be purged is a certain cylinder, the air-fuel ratio of the gas to be purged is measured, and the amount of fuel to be injected from the fuel injection valve 5 of the cylinder is reduced. Thus, it is possible to eliminate the fluctuation of the air-fuel ratio among the cylinders due to the different distribution of the purge gas, and the cost is lower than in the case of piping all the cylinders.

Therefore, as shown in FIG. 11, for the cylinder without purge, the amount of fuel calculated from the operating state of the engine is injected, but for the purge cylinder, the amount of fuel obtained by subtracting the fuel amount for the purge is used. The injection signal is made different so that injection is performed. Further, as shown in FIG. 11, the purge period is set when the purge cylinder is not in the intake stroke, and the purge is not performed while the intake valve is open. That is, during this intake stroke, the electromagnetic on-off valve 40 is turned off to close the valve, and the purge passage 19 is closed to prevent purging.

In the case of a multi-cylinder system, since any one of the cylinders is always in the intake stroke, the inside of the intake pipe 4 is always in a negative pressure state, and it goes without saying that the purge cylinder is purged even in other than the intake stroke. The reason that the purge is not performed during the intake stroke is that, when the purge is performed during the intake, the amount of fuel contained in the purged fuel evaporative gas can be calculated as described above. This is because the next cycle will occur.

Further, as shown in FIG. 10, the position of the purge port 20 to the intake pipe 4 of the purge cylinder is set at a position where the fuel injected from the fuel injection valve 5 of the purge cylinder is not sprayed. The reason why the fuel flow is not allowed to enter when the wall flow is formed in the intake pipe 4 is that if the fuel enters the purge passage 19 while being in a liquid state and covers the transparent glass windows 24a and 24b, a gas phase state is formed. This is because the absorptance of the laser beam changes between the liquid state and the liquid phase state, causing a large error in the air-fuel ratio measurement.

FIG. 12 shows an embodiment corresponding to the fifth invention. In the embodiment of FIG. 12, the same elements as those of the embodiment of FIG. 1 are denoted by the same reference numerals, the description thereof will be omitted, and different elements will be mainly described. The upper space of the fuel tank 14 for processing the fuel evaporative gas generated in the fuel tank 14,
Through the fuel check valve 15 and the passage 16, the canister
Connected to 17. Purge passage 19 from canister 17
Is connected to a purge port 20 provided in the intake pipe 4.

As a secondary air supply device, a secondary air supply passage 51 for supplying air upstream of the throttle valve 3 as secondary air to the purge passage 19 is provided. A secondary air control valve 52 as secondary air supply amount control means is interposed. The operation of the secondary air control valve 52 is controlled by the control unit 6 as described later.

In the purge passage 19 downstream of the connection of the secondary air supply passage 51, a fuel evaporative gas air-fuel ratio detecting means is provided. That is, transparent glass windows 24a and 24b are installed on the passage wall of the purge passage 19 so that the infrared laser light can cross the inside of the passage, and a laser oscillator 25 is provided so as to face one of the transparent glass windows 24a. the oscillator 25 are so as to irradiate the infrared laser beam L ₁ to the fuel evaporative emission in the passage. Also, by relatively to the other transparent glass window 24b, the provided photoelectric conversion element 26 for receiving the laser beam L ₂ after having traversed the passageway, there enter the signal of the photoelectric conversion element 26 to the control unit 6 .

A purge control valve 53 is provided in the purge passage 19 downstream of the fuel evaporative gas air-fuel ratio detecting means. The operation of the purge control valve 53 is also controlled by the control unit 6 as described later. Next, FIG. 13 shows a flow of control executed by the control unit 6.
The operation will be described with reference to the flowchart of FIG.

FIG. 13 shows a secondary air control valve 52 and a purge control valve.
53 is a control routine. In step 31, the photoelectric conversion element
Based on the signal from 26, the air-fuel ratio of the fuel evaporative gas in the purge passage 19 (purge passage A / F) is read. In step 32, the detected purge passage A / F is compared with the lower limit value min on the dark side of the measurable range by the infrared laser light. If the purge passage A / F <lower limit value min, the purge passage A / F is set to the lower limit value min. Since it is darker than the measurable range, the routine proceeds to step 33, where the opening of the secondary air control valve 52 is increased. Thereby, the supply amount of the secondary air is increased to dilute the fuel evaporative gas, and the purge passage A / F is set to a measurable range.

When the purge passage A / F ≧ the lower limit value min,
Proceed to step 34. In step 34, the detected purge passage A / F is compared with the upper limit value max on the thinner side of the measurable range by the infrared laser beam, and if the purge passage A / F> upper limit max, the purge passage A / F is Since it is thinner than the measurable range, the routine proceeds to step 35, where it is determined whether or not the secondary air control valve 52 is open (ON).
Then, the secondary air control valve 52 is closed (OFF).
As a result, the supply of the secondary air is stopped, and the purge passage A
/ F is shifted to the dark side so that the purge passage A /
Let F be the measurable range.

However, if the purge passage A / F does not fall within the measurable range even after the supply of the secondary air is stopped, the purge control valve 53 is closed to stop the supply of the fuel evaporative gas. Therefore, if it is determined in step 35 that the secondary air control valve 52 is in the closed state, the process proceeds to step 37, in which the purge control valve 53 is closed (OFF). If the result of determination in steps 32 and 34 is that lower limit value min ≦ purge passage A / F ≦ upper limit value max, the routine proceeds to step 38, where it is determined whether or not the purge control valve 53 is closed (OFF). If closed, step
Proceeding to 39, the purge control valve 53 is opened (ON).

While the engine is stopped, the secondary air control valve 52
Then, the power supply to the purge control valve 53 is stopped, and both of them are closed. As a result, the fuel evaporative gas from the fuel tank 14 easily stays in the canister 17. FIG. 14 is a control routine for correcting the fuel injection amount. In step 41, the intake pressure Pa is read based on the signal from the intake pressure sensor 7, in step 42, the intake temperature Ta is read based on the signal from the intake temperature sensor 8, and in step 43, the intake pressure Pa and the intake temperature Ta are calculated. The intake air amount Q is calculated based on the calculated amount. In step 44, a fuel amount Ft for obtaining the target A / F is calculated based on the intake air amount Q and the engine speed N.

In step 45, it is determined whether or not the purge control valve 53 is in the open state. If YES, the process proceeds to step 46, and if NO, the process proceeds to step 50. In step 46, the photoelectric conversion element
Based on the signal from 26, the air-fuel ratio of the fuel evaporative gas in the purge passage 19 (purge passage A / F) is read. In step 47, the intake volume Vp of the gas to be purged into the intake pipe 4 is calculated from the intake pressure Pa and the intake temperature Ta. Purge passage 19
The amount of gas introduced from the intake pipe 4 into the intake pipe 4 is related to the negative pressure of the intake pipe 4 and the cross-sectional area of the purge passage 19, and is sucked into the intake pipe 4 during the time when the intake is performed and the suction negative pressure is generated. Therefore, if time integration is performed, the volume can be determined.

In step 48, the amount of fuel Fp purged from the purge gas suction volume Vp and the purge passage A / F is calculated. In step 49, the fuel injection amount Fi = Ft−Fp by the fuel injection valve 5 is calculated by subtracting the purge fuel amount Fp from the target A / F fuel amount Ft. This part corresponds to the correction means.

On the other hand, if the determination in step 45 is NO, that is, if the purge control valve 53 is closed, the routine proceeds to step 50, where the fuel injection amount Fi is set to Ft without correction.
When the fuel injection amount Fi is calculated, a drive pulse signal having a pulse width corresponding to the calculated fuel injection amount Fi is output to the fuel injection valve 5 at a predetermined timing in synchronization with the engine rotation, and fuel injection is performed.

In the present embodiment, the purge passage A / F is controlled within a predetermined range for the following reason. The concentration of the fuel evaporative gas supplied from the canister 7 varies in a wide range from a high concentration to a low concentration. Since the infrared absorption method measures the air-fuel ratio by the absorption amount according to the fuel concentration of the laser light, measuring the air-fuel ratio in a wide range increases the laser light oscillation intensity and does not absorb all the laser light even at a deep air-fuel ratio You need to do that. However, the cost of the high-output laser oscillator 25 increases, and the cost of the photoelectric conversion element 26 also needs to be high, which further increases the cost.

Therefore, instead of making it possible to measure the entire range in which the purge passage A / F changes, a certain range of A / F
The setting is made so that F can be measured. If the purge passage A / F is deeper than the measurable range, dilution is performed by introducing secondary air. If the purge passage A / F is thinner than the measurable range, first, the purge passage A / F is diluted. The secondary air control valve 52 is closed to stop dilution with the secondary air. If the concentration is still low, the purge control valve 53 is closed to stop purging. With these controls, the purge passage A / F can be kept within the measurable range at all times, and by performing correction to reduce the fuel amount of the purge passage A / F from the fuel injection amount, the empty space corresponding to the engine operating state can be obtained without delay. The fuel ratio can be controlled.

When the purge passage A / F is deeper than the measurable range, the opening degree is gradually increased without suddenly opening the secondary air control valve 52 fully. This is for keeping the A / F close to the lower limit on the deep side as much as possible to consume the fuel evaporative gas in the canister 7 as soon as possible. When the purge passage A / F is thinner than the measurable range, the secondary air control is performed. The reason why the valve is suddenly fully closed is to promptly shift the purge passage A / F to the rich side so that the fuel evaporative gas in the canister 7 is consumed as soon as possible.

In this embodiment, the purging is stopped when the purge passage A / F is thinner than the measurable range. However, if the effect on the air-fuel ratio of the engine is small, the purging is continued. Alternatively, the consumption of the fuel evaporative gas in the canister 7 may be promoted. FIG. 15 shows an embodiment corresponding to the sixth invention.

In the embodiment of FIG. 15, the same elements as those of the embodiment of FIG.
The description focuses on the different elements. The upper space of the fuel tank 14 is connected to a canister 17 through a passage 16 via a fuel check valve 15 for processing the fuel evaporative gas generated in the fuel tank 14. A purge passage 19 from the canister 17 is connected to a purge port 20 provided in the intake pipe 4. The check valve 15 is a check valve for releasing the fuel evaporative gas to the canister 17 side when the tank internal pressure rises to the atmospheric pressure + α or more so that the pressure in the fuel tank 14 does not become too high. .

The canister 17 and the fuel check valve 15
A bypass passage 61 is provided to guide the fuel evaporative gas in the fuel tank 14 to the purge port 20 of the intake pipe 4 to bypass the fuel tank 14. Further, a first control valve 62 is interposed in the purge passage 19, and a second control valve 63 is interposed in the bypass passage 61. The operation of the first and second control valves 62 and 63 is controlled by the control unit 6 as described later.

The purge passage upstream of the first control valve 62
19, a first fuel evaporative gas air-fuel ratio detecting means is provided. That is, a transparent glass window is provided on the passage wall of the purge passage 19.
24a and 24b are set so that the infrared laser beam crosses the inside of the passage, and a laser oscillator 25 is provided so as to face one of the transparent glass windows 24a. Irradiation is performed on the evaporative gas. Further, a photoelectric conversion element 26 for receiving the laser light after traversing the passage is provided opposite to the other transparent glass window 24b,
The signal of the photoelectric conversion element 26 is input to the control unit 6.

In the bypass passage 61 upstream of the second control valve 63, a second fuel evaporative gas air-fuel ratio detecting means is provided. That is, the transparent glass windows 64a and 64b are installed on the passage wall of the bypass passage 61 so that the infrared laser light crosses the inside of the passage, and the laser oscillator 65 is provided so as to face the one transparent glass window 64a. The oscillator 65 irradiates infrared laser light to the fuel evaporative gas in the passage. Further, a photoelectric conversion element 66 for receiving the laser beam after traversing the inside of the passage is provided opposite to the other transparent glass window 64b, and the signal of this photoelectric conversion element 66 is input to the control unit 6.

[0068] Further, a pressure sensor 67 provided in the upper space of the fuel tank 14, and inputs the signal of the pressure sensor 66 to the control unit 6, are then adapted to detect the pressure P ₁ in the fuel tank 14. Next, the control unit 6
The operation will be described with reference to the flowcharts of FIGS. 16 and 17 showing the flow of the control executed by.

FIG. 16 is a control routine for the first and second control valves 62 and 63. This routine corresponds to control valve control means. In step 51, the purge passage is determined based on a signal from the photoelectric conversion element 26 which constitutes the first fuel evaporative gas air-fuel ratio detecting means.
The air-fuel ratio (purge passage A / F) X of the fuel evaporative gas in 19 is read.

In step 52, the air-fuel ratio (bypass passage A / F) Y of the fuel evaporation gas in the bypass passage 61 is read based on the signal from the photoelectric conversion element 66 constituting the second fuel evaporative gas air-fuel ratio detecting means. . In step 53, the purge passage A / F
(X) is compared with the bypass passage A / F (Y), and X ≦ Y
If (X is darker), go to step 55.

In step 55, the purge passage A / F (X)
Is darker, the first control valve 62 is opened, and the second control valve 62 is opened.
By closing the control valve 63, the fuel vapor in the canister 7 is purged through the purge passage 19. still,
The reason why the second control valve 63 is closed is that the purge flow rate depends on the upstream and downstream differential pressures and the flow path diameter. Therefore, if the number of flow paths is reduced to two, the purge flow rate on the canister 7 side decreases accordingly. .

If the result of the comparison in step 53 is that X> Y (Y is darker), the flow proceeds to step 54 where the pressure sensor 67
Based on a signal from detecting the pressure P ₁ in the fuel tank 14, it is determined whether the pressure P ₁ is above atmospheric pressure. If P ₁ > atmospheric pressure, the routine proceeds to step 56. In step 56, denser towards the bypass passage A / F (Y), and the pressure P ₁ in the fuel tank 14 is above atmospheric pressure, closing the first control valve 62, the second control valve 63 By opening the fuel tank through the bypass passage 61
Purge the fuel evaporative gas from 14 directly.

However, even if the bypass passage A / F (Y) is darker, the fuel tank 14
If the pressure P ₁ of the inner is less than atmospheric pressure, the program proceeds to step 55, opens the first control valve 62, by closing the second control valve 63, through the purge passage 19, the fuel vaporization in the canister 7 Purge gas. In this case, the second control valve 63
This is because there is a possibility that the gas flows backward to the fuel tank 14 side even if it is opened.

FIG. 17 is a control routine for correcting the fuel injection amount. In step 61, the intake pressure Pa is read based on the signal from the intake pressure sensor 7, in step 62, the intake temperature Ta is read based on the signal from the intake temperature sensor 8, and in step 63, the intake pressure Pa and the intake temperature Ta are calculated. The intake air amount Q is calculated based on the calculated amount. Then, in step 64, the fuel amount Ft for obtaining the target A / F is calculated based on the intake air amount Q and the engine speed N.

In step 65, it is determined whether or not the first control valve 62 is in the open state.
If it is (the second control valve 63 is in the open state), the process proceeds to step 67. In step 66, the purge passage is determined based on the signal from the photoelectric conversion element 26 which constitutes the first fuel evaporative gas air-fuel ratio detecting means.
After reading the air-fuel ratio (purge passage A / F) X of the fuel evaporative gas in 19, the routine proceeds to step 68.

In step 67, the air-fuel ratio (bypass passage A / F) Y of the fuel evaporative gas in the bypass passage 61 is read based on a signal from the photoelectric conversion element 66 constituting the second fuel evaporative gas air-fuel ratio detecting means. After that, go to step 68. Steps
In 68, the suction volume Vp of the gas purged into the suction pipe 4 is calculated from the suction pressure Pa and the suction temperature Ta. The amount of gas introduced into the intake pipe 4 from the purge passage 19 or the bypass passage 61 depends on the negative pressure of the intake pipe 4 and the purge passage 19 or the bypass passage.
This is because, in relation to the cross-sectional area of 61, the air is taken into the intake pipe 4 during the time when the suction is performed and the suction negative pressure is generated.

In step 69, the amount of fuel Fp purged from the purge gas suction volume Vp calculated in step 68 and the purge passage A / F or bypass passage A / F read in step 66 or 67 is calculated. Then, in step 70, the fuel injection amount Fi = Ft-Fp by the fuel injection valve 5 is calculated by subtracting the purge fuel amount Fp from the target A / F fuel amount Ft. This part corresponds to the correction means.

When the fuel injection amount Fi is calculated, a drive pulse signal having a pulse width corresponding to the calculated fuel injection amount Fi is output to the fuel injection valve 5 at a predetermined timing in synchronization with the engine rotation, and fuel injection is performed. According to the present embodiment, when a large amount of fuel evaporative gas is adsorbed in the canister 17, such as when the engine is started, the fuel evaporative gas in the canister 17 is purged by the purge passage 19. As a result of the comparison between the air-fuel ratio of the fuel evaporative gas and the air-fuel ratio of the fuel evaporative gas in the bypass passage 61, the air-fuel ratio of the fuel evaporative gas from the bypass the pressure P ₁ of the inner is if exceeds the atmospheric pressure, by conducting the bypass passage 61, directly leading to the intake pipe of the engine fuel vapor from the fuel tank 14. In this way, the fuel evaporative gas in the fuel tank 14 is actively purged without passing through the canister 17 to thereby concentrate the fuel.
Without causing the fuel vapor to pass through the canister 7, the load on the activated carbon can be reduced, and the life can be prolonged.

Further, since the internal pressure of the fuel tank 14 can be reduced, there is an advantage that escape of fuel vapor at the time of refueling can be prevented.

[0080]

As described above, according to the first aspect, the air-fuel ratio (fuel concentration) of the fuel evaporative gas can be directly detected from the absorptivity of the infrared laser light. The control accuracy is improved. According to the second aspect of the present invention, when the engine is started, the fuel evaporative gas in both the fuel tank and the canister is supplied to the intake pipe until the warm-up is completed. By reducing the amount of fuel supplied from a fuel injection valve or the like that easily causes a fuel wall flow, it is possible to obtain an effect of improving the stability of combustion and the emission of exhaust gas.

According to the third aspect, when the fuel evaporative gas is liquefied in the purge passage, high-temperature exhaust gas at the time of exhaust gas recirculation is introduced into the purge passage.
The effect is obtained that the liquefied fuel is vaporized, unburned HC can be suppressed, and the detection accuracy of the air-fuel ratio of the fuel evaporative gas can be maintained. According to the fourth aspect of the present invention, further, by concentrating the fuel evaporative gas on one specific cylinder, an effect of preventing the air-fuel ratio from shifting between the cylinders can be obtained.

According to the fifth aspect of the present invention, by controlling the secondary air, the air-fuel ratio of the fuel evaporative gas can always be controlled within the measurable range by the infrared laser beam, thereby enabling accurate measurement. Thus, the effect of further improving the control accuracy of the air-fuel ratio can be obtained. According to the sixth invention,
Further, when the air-fuel ratio of the fuel evaporative gas from the fuel tank is higher than the air-fuel ratio of the fuel evaporative gas in the canister, the fuel evaporative gas from the fuel tank is led directly to the intake pipe of the engine, thereby increasing the fuel density. Evaporated gas passes through the canister
The effect is that the burden can be reduced and the life can be prolonged without letting it go.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment corresponding to the first and second inventions;

FIG. 2 is an enlarged view of a fuel evaporative gas air-fuel ratio detection unit.

FIG. 3 is a flowchart showing a control flow.

FIG. 4 is a diagram showing a flow of a fuel evaporative gas.

FIG. 5 is a system diagram showing an embodiment corresponding to the third invention.

FIG. 6 is an enlarged view of a gas-liquid state determination unit.

FIG. 7 is an explanatory diagram of gas-liquid state determination.

FIG. 8 is a flowchart of vaporization control.

FIG. 9 is a system diagram showing an embodiment corresponding to the fourth invention.

FIG. 10 is an enlarged view of a purge port portion.

FIG. 11 is an explanatory diagram of a purge period.

FIG. 12 is a system diagram showing an embodiment corresponding to the fifth invention.

FIG. 13 is a flowchart showing the flow of secondary air control.

FIG. 14 is a flowchart showing the flow of fuel injection amount correction control.

FIG. 15 is a system diagram showing an embodiment corresponding to the sixth invention.

FIG. 16 is a flowchart showing the flow of purge control.

FIG. 17 is a flowchart showing the flow of fuel injection amount correction control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 4 Intake pipe 5 Fuel injection valve 6 Control unit 11 Exhaust pipe 14 Fuel tank 15 Fuel check valve 16 Passage 17 Canister 19 Purge passage 20 Purge port 21 Bypass passage 22 Electromagnetic switching valve 23 Electromagnetic on-off valve 24a, 24b Transparent glass window 25 Laser oscillator 26 Photoelectric conversion element 33 Exhaust gas recirculation device 34 Electromagnetic switching valve 35 Exhaust gas recirculation port 51 Secondary air supply passage 52 Secondary air control valve 53 Purge control valve 61 Bypass passage 62 First control valve 63 Second control valve 64a, 64b Transparent glass window 65 Laser oscillator 66 Photoelectric conversion element 67 Pressure sensor

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁷ Identification code FI F02D 41/14 310 F02D 41/14 310P 43/00 301 43/00 301H 301M 301N 45/00 364 45/00 364K F02M 25/08 301 F02M 25/08 301J 301U (56) References JP-A-5-59977 (JP, A) JP-A-3-96640 (JP, A) JP-A-1-237435 (JP, A) JP-A-63-63 248951 (JP, A) JP-A-60-188815 (JP, A) JP-A-60-192219 (JP, A) JP-A-6-288283 (JP, A) JP-A-6-280669 (JP, A) JP-A-6-288282 (JP, A) JP-A-6-347025 (JP, A) JP-A-61-36145 (JP, U) JP-A-59-7257 (JP, U) JP-A-59-45264 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F02D 41/04 330 F02D 21/08 301 F02D 41/02 330 F02D 41/14 310 F02D 43/00 301 F02D 45/00 364 F02M 25/08 301

Claims (6)

(57) [Claims] 1. A canister for temporarily adsorbing fuel evaporative gas in a fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of an engine, and a fuel evaporative gas in the purge passage. A fuel evaporative gas air-fuel ratio detecting means for irradiating the infrared laser light and detecting an air-fuel ratio of the fuel evaporative gas based on a rate at which the fuel evaporative gas absorbs the infrared laser light; Correction means for reducing the amount of fuel supplied to the engine based on the air-fuel ratio, and fuel supply means for supplying a fuel amount corresponding to the output of the correction means to the intake pipe of the engine. Evaporative gas treatment equipment for engines. 2. A canister for temporarily adsorbing fuel evaporative gas in a fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of an engine, and a fuel tank that bypasses the canister. A bypass passage for guiding the fuel evaporative gas to the middle of the purge passage; and a switch between introduction of the fuel evaporative gas in a fuel tank into the canister and introduction into the bypass passage,
A switching valve for introducing the fuel evaporative gas in the fuel tank to the canister when the engine is stopped, and for introducing the fuel evaporative gas to the bypass passage during operation including engine start, and the purge passage upstream of a connection position of the bypass passage. An on-off valve that is disposed and opens until warm-up is completed when the engine is started, and irradiates the fuel vapor gas in the purge passage downstream of the connection position of the bypass passage with an infrared laser beam so that the fuel vapor gas is emitted. Fuel evaporative gas air-fuel ratio detecting means for detecting the air-fuel ratio of the fuel evaporative gas based on the rate of absorbing the infrared laser light; and a fuel amount supplied to the engine based on the detected air-fuel ratio of the fuel evaporative gas. And a fuel supply means for supplying a fuel amount corresponding to an output of the correction means to an intake pipe of the engine. Processing apparatus. 3. A canister for temporarily adsorbing fuel evaporative gas in a fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of the engine, and exhaust gas from the engine via a switching valve. An exhaust gas recirculation device capable of returning to the purge passage, gas-liquid state determination means for determining a gas-liquid state of the fuel in the purge passage, and a fuel-liquid state in the purge passage based on the determination result. At one time, vaporizing means for switching a switching valve of the exhaust gas recirculation device to recirculate exhaust gas in the purge passage and vaporize fuel in the purge passage; and infrared laser light for evaporating fuel in the purge passage. And a fuel evaporative gas air-fuel ratio detecting means for detecting an air-fuel ratio of the fuel evaporative gas based on a rate at which the fuel evaporative gas absorbs the infrared laser light. And a fuel supply means for supplying a fuel amount corresponding to an output of the correction means to an intake pipe of the engine based on the correction value. Of fuel evaporative gas treatment equipment. 4. A fuel evaporative gas treatment apparatus for a multi-cylinder engine having a plurality of cylinders and a plurality of fuel supply means for supplying fuel to intake pipes corresponding to the cylinders, respectively. A canister for temporarily adsorbing the fuel evaporative gas; a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of a specific one cylinder of the engine; And a fuel evaporative gas air-fuel ratio detecting means for detecting an air-fuel ratio of the fuel evaporative gas based on a rate at which the fuel evaporative gas absorbs the infrared laser light. And e. A correction means for reducing the amount of fuel supplied to the specific one cylinder of the engine by the fuel supply means. 5. A canister for temporarily adsorbing fuel evaporative gas in a fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of an engine, and a secondary air supply to the purge passage. A secondary air supply device for irradiating the fuel vapor gas in the purge passage with an infrared laser beam, and detecting an air-fuel ratio of the fuel vapor gas based on a rate at which the fuel vapor gas absorbs the infrared laser beam. A fuel evaporating gas air-fuel ratio detecting means, a correcting means for reducing the amount of fuel supplied to the engine based on the detected air-fuel ratio of the fuel evaporating gas, and a fuel amount corresponding to the output of the correcting means. Fuel supply means for supplying to the intake pipe; and the secondary air so that the air-fuel ratio falls within a predetermined range based on the air-fuel ratio of the fuel evaporative gas detected by the fuel evaporative gas air-fuel ratio detection means. Fuel evaporative emission treatment system for an engine, characterized in that it and a secondary air supply amount control means for controlling the supply amount of the secondary air by feeding device. 6. A canister for temporarily adsorbing fuel evaporative gas in a fuel tank, a purge passage for guiding the fuel evaporative gas adsorbed by the canister to an intake pipe of an engine, and a purge passage provided in the purge passage. A control valve, a bypass passage that bypasses the canister and the first control valve and guides fuel evaporative gas in a fuel tank to an intake pipe of an engine, and a second control valve that is disposed in the bypass passage. Irradiating the fuel vapor gas in the purge passage upstream of the first control valve with infrared laser light, and evaporating the fuel vapor in the purge passage based on the rate at which the fuel vapor gas absorbs the infrared laser light. First fuel evaporative gas air-fuel ratio detecting means for detecting the air-fuel ratio of the gas; and irradiating the fuel evaporative gas in the bypass passage upstream of the second control valve with infrared laser light. Laser light The second fuel evaporative gas air-fuel ratio detecting means for detecting the air-fuel ratio of the fuel evaporative gas in the bypass passage based on the rate of recovery, and the first and second fuel evaporative gas air-fuel ratio detecting means detect the air-fuel ratio. Comparing the air-fuel ratio of the fuel-evaporated gas with the air-fuel ratio of the fuel-evaporated gas and opening the control valve of the first and second control valves in the passage on the side where the air-fuel ratio of the fuel-evaporated gas is higher.
At the same time, the control valve control means for closing the control valve in the passage on the side where the air-fuel ratio is thin, and the air-fuel ratio of the fuel evaporative gas detected in the passage on the side where the control valve is opened. And a fuel supply means for supplying a fuel amount corresponding to an output of the correction means to an intake pipe of the engine based on the correction means. Fuel evaporative gas treatment equipment.