JP2005030367A - Hydrocarbon emission reduction device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce the discharge of hydrocarbon from an internal combustion engine. <P>SOLUTION: In the engine, a secondary air is supplied from a secondary air supply pump 33 to an exhaust tube 21 through an exhaust side air passage 32. Also, an intake side air passage 35 is connected so as to be branched from the exhaust side air passage 32, and the tip of the intake side air passage 35 is connected to an intake manifold 16. An HC adsorbing material 31 is installed in an air cleaner 12 on the upstream-most side of the intake tube. An ECU 50 fills air to the intake manifold 16 by driving the secondary air supply pump 33 when the engine is stopped. Thus, the hydocarbon suspending near the intake port is forced out toward the upstream side of the intake tube 11, and adsorbed onto the HC adsorbing material 31. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a hydrocarbon emission reduction device for an internal combustion engine that reduces the emission of hydrocarbons (hereinafter also referred to as “HC”) from the internal combustion engine.

In an internal combustion engine, fuel (HC) remains in the vicinity of an intake port due to fuel leaking from a fuel injection valve (oil-tight leak), fuel blowback from a combustion chamber, fuel inflow from a PCV (Positive Crankcase Ventilation) passage, and the like. The fuel (HC) remains even after the operation of the internal combustion engine is stopped. In a multi-cylinder internal combustion engine, fuel (HC) remains in the intake manifold. If this residual HC is left unattended, the next time the engine is started, the floating hydrocarbons near the intake port are sucked into the combustion chamber along with cranking by a starter motor or the like, and are further discharged unburned. Arise.

Therefore, Patent Documents 1 to 3 listed below have been proposed as conventional techniques for solving the above inconvenience. That is, in Patent Document 1, an adsorbent is provided between the throttle valve of the internal combustion engine and the engine body, and the fuel leaked from the fuel injection valve is adsorbed by the adsorbent. In Patent Document 2, HC is provided in an intake passage of an internal combustion engine.
An adsorbent is provided, and HC remaining in the intake passage is removed by the HC adsorbent. Further, in Patent Document 3, while the internal combustion engine is stopped, HC remaining in the intake passage is temporarily stored in the HC adsorbent, and the stored HC is released after the catalyst is activated or a predetermined time has elapsed since the engine is started. I am doing so.

Each of the above prior arts is consistent in that an HC adsorbent is installed in the intake passage of the internal combustion engine, and such a configuration can effectively adsorb HC components.
JP 11-82192 A JP 2001-227421 A Japanese Patent Laid-Open No. 2001-234781

However, the following problems occur in the above-described conventional technology. That is, during the operation of the internal combustion engine, high boiling point HC is mixed and floats in the vicinity of the intake port due to fuel blowback from the combustion chamber, fuel inflow from the PCV passage (especially engine oil inflow in the fuel), and the like. In such a case, in the configuration in which the HC adsorbent is installed in the intake passage as described above, HC having a high boiling point adheres to the HC adsorbent. Since the high boiling point HC once adsorbed to the HC adsorbent is not released thereafter, the HC adsorbing performance of the HC adsorbent is remarkably deteriorated, resulting in a problem that a sufficient HC reduction effect cannot be obtained.

In Patent Document 2, it is proposed to install the HC adsorbent upstream of the throttle valve, for example, in an air cleaner, or to use a canister for adsorbing fuel evaporative gas generated in the fuel tank as the HC adsorbent. ing. Since the high boiling point HC has a shorter floating distance from the engine body than the low boiling point HC, the above configuration makes it difficult for the high boiling point HC to adhere to the HC adsorbent during engine operation. Conceivable. However, in the configuration in which the HC adsorbent is installed upstream of the throttle, or in the configuration in which the canister is used as the HC adsorbent, the low boiling point HC remaining in the vicinity of the intake port is effective even if the engine temperature drops after the engine stops. When the engine is started next time, there is a problem that HC in the vicinity of the intake port is sucked into the combustion chamber along with cranking by a starter motor or the like, and is discharged unburned.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a hydrocarbon emission reduction device for an internal combustion engine that can effectively reduce the emission of hydrocarbons.

In the hydrocarbon emission reduction device according to the first aspect, air is injected by the air injection means at or near the intake port in the intake passage of the internal combustion engine. The hydrocarbon adsorbent for adsorbing hydrocarbons is installed in a place that leads to the vicinity of the intake port and does not float hydrocarbons with a high boiling point. Then, the air injection means is driven to generate the air flow while the operation of the internal combustion engine is stopped. As a result, even after the engine temperature has dropped, hydrocarbons that float in the vicinity of the intake port are sent out toward the hydrocarbon adsorbent and are adsorbed by the hydrocarbon adsorbent. It should be noted that the high-boiling point hydrocarbon does not float so long as the high-boiling point hydrocarbon floating amount does not exceed a predetermined reference level.

In short, after the internal combustion engine is shut down, hydrocarbons (unburned fuel) and oil remain near the intake port in the intake passage, and some of them float near the intake port. These hydrocarbons liquefy and only low boiling point hydrocarbons float near the intake port. When the internal combustion engine is stopped, air injection is performed after the temperature of the engine has dropped, etc., so that low-boiling hydrocarbons floating near the intake port are efficiently adsorbed by the hydrocarbon adsorbent. Also, during operation of the internal combustion engine, high boiling point hydrocarbons are mixed and floated in the vicinity of the intake port due to fuel blowback from the combustion chamber, etc., but in the present invention, the hydrocarbon adsorbent does not float Because it was installed in
During engine operation, floating hydrocarbons are not adsorbed on the hydrocarbon adsorbent, and a decrease in hydrocarbon adsorption performance can be suppressed. As described above, at the time of the next engine start, it is possible to suppress a situation in which the floating hydrocarbons near the intake port are sucked into the combustion chamber and discharged without being burned due to cranking. As a result, hydrocarbon emissions can be effectively reduced.

In the second aspect of the present invention, the air injection passage is connected to or near the intake port of the internal combustion engine, and air is injected into the air injection passage by the air injection means. A pump or the like is not necessarily provided in the vicinity of the intake port, and the degree of freedom in realizing the present hydrocarbon emission reduction device can be increased.

In the third aspect of the invention, since the air injection means is configured to inject air into the branch portion branched from the intake manifold portion in the multi-cylinder internal combustion engine, hydrocarbons mainly floating in the vicinity of the intake port are efficiently removed. Can be removed. The branch portion corresponds to an intake manifold.

According to a fourth aspect of the present invention, an air-assisted fuel injection valve is applied, in which air is ejected from the tip of the fuel injection valve to atomize the fuel spray, and the assist air outlet for the fuel injection valve is applied. In contrast, air injection is performed by the air injection means. In this case, since air is injected from the tip of the fuel injection valve (assist air outlet), even if a large amount of hydrocarbon remains in the vicinity of the intake port, it can be efficiently removed. Moreover, cost can be prevented by diverting the existing assist air ejection port.

In the invention according to claim 5, since the installation location of the hydrocarbon adsorbent is a location where an air flow to the engine combustion chamber is generated during operation of the internal combustion engine, the hydrocarbon once adsorbed by the hydrocarbon adsorbent Is separated by the air flow to the engine combustion chamber during engine operation, and is sucked into the engine combustion chamber. Thereby, the hydrocarbon adsorption capacity in the hydrocarbon adsorbent is recovered.

In the invention according to claim 6, since the hydrocarbon adsorbent is disposed in the air cleaner provided in the most upstream part of the intake passage, the hydrocarbon having a high boiling point near the intake port is hydrocarbon during engine operation. There is no fear of adsorbing to the adsorbent, and hydrocarbons adsorbed while the engine is stopped are separated by the flow of intake air. Therefore, it is possible to favorably adsorb and release hydrocarbons.

According to the seventh aspect of the present invention, when air is injected near the intake port by the air injection means, the throttle valve provided in the intake passage is opened to a predetermined opening. Thereby, a hydrocarbon can be suitably sent out with respect to the hydrocarbon adsorbent arrange | positioned at the air cleaner.

In the invention described in claim 8, a fuel evaporative gas emission suppression device is provided, and the fuel evaporative gas (evaporative gas) generated in the fuel tank is temporarily adsorbed by the canister, and the fuel adsorbed by the canister is engine. During operation, the air is discharged to the intake passage through the purge passage. In this configuration, the canister is used as the hydrocarbon adsorbent, and the intake passage and the canister are communicated with each other while the operation of the internal combustion engine is stopped. In this case, the cost can be prevented by diverting the existing canister as the hydrocarbon adsorbent.

According to a ninth aspect of the present invention, in the fuel evaporative emission control device, a purge control valve for opening or closing the purge passage is provided in the purge passage, and the internal combustion engine is operated according to the state of the engine during the operation. The purge control valve is opened to release the hydrocarbon adsorbed on the canister. In this case, since the canister purge is performed according to the operating state of the internal combustion engine, an unstable behavior of the internal combustion engine can be prevented at the time of hydrocarbon release.

The invention according to claim 10 comprises a bypass passage that bypasses the throttle valve provided in the intake passage, and an idle speed control valve provided in the bypass passage,
The hydrocarbon adsorbent was provided in the middle of the bypass passage. In this case, it is possible to prevent an increase in cost by diverting the existing bypass passage.

In the invention described in claim 11, the secondary air is supplied from the secondary air supply pump to the catalyst, and this secondary air supply pump is used as the air injection means. Thereby, the secondary air fed from the secondary air supply pump is injected into the vicinity of the intake port, and the hydrocarbons are sent out to the hydrocarbon adsorbent on the secondary air. In this case, the cost can be prevented by using the existing secondary air supply pump as the air injection means.

In the invention of claim 12, when performing air injection near the intake port using the secondary air supply pump, the exhaust side air passage is closed by the open / close control valve,
The intake air passage is opened. Thereby, the air injection to the vicinity of the intake port can be suitably performed.

In the invention described in claim 13, the air flow rate generated by the air injection means is limited to a flow rate at which hydrocarbons do not blow through the hydrocarbon adsorbent. Such restriction of the air flow rate ensures that the hydrocarbon is adsorbed on the hydrocarbon adsorbent.

In the invention described in claim 14, after the operation of the internal combustion engine is stopped, the air injection by the air injection means is performed after a predetermined soak time has elapsed. Specifically, after the operation of the internal combustion engine is stopped, air injection by the air injection means may be performed after a time when the hydrocarbon concentration floating in the vicinity of the intake port is predicted to be stable. Thereby, it is possible to avoid a situation where floating hydrocarbons are generated again after air injection.

According to the fifteenth aspect of the present invention, when the internal combustion engine is stopped, the release of the door lock or the door opening of the vehicle on which the internal combustion engine is mounted is detected, and air injection by the air injection means is performed at the time of detection. In order to reliably prevent hydrocarbon emissions during cranking, it is desirable to remove hydrocarbons floating in the vicinity of the intake port immediately before the start of cranking. Can be suitably performed. Thereby, the discharge | emission of the hydrocarbon at the time of cranking can be prevented more reliably.

In the invention described in claim 16, when the engine temperature is detected and the detected engine temperature is equal to or higher than a predetermined temperature, the air injection by the air injection means is prohibited. When the engine temperature such as engine water temperature, intake air temperature, engine oil temperature, etc. is high, it is considered that high-boiling hydrocarbons are filled in the vicinity of the intake port. Adsorption of hydrocarbons may lead to deterioration of the hydrocarbon adsorbent. Therefore, air injection is prohibited until the high-boiling point hydrocarbons are liquefied due to the engine temperature decreasing. It is also possible to estimate the engine temperature from the transmission oil temperature and prohibit the air injection by the air injection means when the estimated temperature is equal to or higher than a predetermined temperature.

In the invention according to claim 17, the hydrocarbon adsorbent for adsorbing hydrocarbons is such that hydrocarbons in the vicinity of the intake port do not float and downstream of the air flow generated by the air flow generation source. It is installed on the side. Then, when the operation of the internal combustion engine is stopped, an air flow is forcibly generated in the intake passage of the internal combustion engine by the air flow generation source. Thereby, the hydrocarbon floating in the vicinity of the intake port is sent out toward the hydrocarbon adsorbent, and is adsorbed by the hydrocarbon adsorbent.

In the present invention, similarly to the first aspect of the present invention, when the operation of the internal combustion engine is stopped, hydrocarbons floating in the vicinity of the intake port are efficiently adsorbed by the hydrocarbon adsorbent. Also, during operation of the internal combustion engine, high boiling point hydrocarbons are mixed and floated in the vicinity of the intake port due to fuel blowback from the combustion chamber, etc., but in the present invention, the hydrocarbon adsorbent does not float Therefore, floating hydrocarbons are not adsorbed to the hydrocarbon adsorbent during engine operation, and a decrease in hydrocarbon adsorption performance can be suppressed. As described above, at the time of the next engine start, it is possible to suppress a situation in which floating hydrocarbons near the intake port are sucked into the combustion chamber and discharged unburned with cranking. As a result, hydrocarbon emissions can be effectively reduced.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. The present embodiment embodies a hydrocarbon emission reduction device for a four-cylinder gasoline injection engine mounted on a vehicle, and FIG. 1 is a configuration diagram showing an outline of the engine control system.

As shown in FIG. 1, in the engine 10, an air cleaner 12 is provided at the most upstream portion of the intake pipe 11, and an air flow meter 13 for detecting the intake air amount is provided downstream thereof. The air flow meter 13 incorporates an intake air temperature sensor for detecting the intake air temperature. On the downstream side of the air flow meter 13, a throttle valve 1 whose opening degree is adjusted by a throttle actuator 14 a such as a DC motor.
4 is provided. A surge tank 1 is provided downstream of the throttle valve 14.
The surge tank 15 is connected with an intake manifold 16 for introducing air into each cylinder of the engine 10. A fuel injection valve 17 is attached to the intake port of each cylinder of the intake manifold 16. The intake pipe 11,
The surge tank 15 and the intake manifold 16 constitute an intake passage.

The exhaust pipe 21 is provided with a catalyst 22 such as a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas, and the upstream side of the catalyst 22 detects the exhaust gas as a detection target, or the air-fuel ratio of the air-fuel mixture or An air-fuel ratio sensor 23 (linear air-fuel ratio sensor, oxygen sensor, etc.) for detecting rich / lean is provided.

The air cleaner 12 is provided with an HC adsorbent 31 formed of at least one of activated carbon, zeolite, and a catalyst component having a hydrocarbon adsorbing action.

Further, in this system, the secondary air is supplied to the catalyst 22 so that the catalyst 2
2 early activity is intended. As its configuration, an exhaust side air passage 32 is connected to the exhaust pipe 21, and secondary air is supplied from the secondary air supply pump 33 to the exhaust pipe 21 through the exhaust side air passage 32. Yes. An exhaust side opening / closing valve 34 is provided in the middle of the exhaust side air passage 32. An intake side air passage 35 is connected between the secondary air supply pump 33 and the exhaust side on-off valve 34 so as to branch from the exhaust side air passage 32. Is connected to the intake manifold 16. An intake side on-off valve 36 is provided midway in the intake side air passage 35. Note that the secondary air supply pump 33 is provided with air injection means (
The exhaust flow side open / close valve 34 and the intake side open / close valve 36 correspond to open / close control valves.

In such a configuration, when the operation of the engine 10 is started, the exhaust side opening / closing valve 34 is opened so that the secondary air from the secondary air supply pump 33 is supplied to the exhaust pipe 21 via the exhaust side air passage 32, and the catalyst 22. Early activity. On the other hand, when the engine is stopped, the secondary air supply pump 3 is opened by opening the intake side on-off valve 36.
3 is supplied to the intake manifold 16 via the intake air passage 35, and air is injected into the vicinity of the intake port.

An electronic control unit (hereinafter referred to as an ECU) 50 is configured around a microcomputer, and the ECU 50 includes an air-fuel ratio detection signal of the air-fuel ratio sensor 23 described above,
In addition, an intake air amount signal, an intake air temperature signal, an engine coolant water temperature signal, an engine speed signal, an accelerator opening signal, an ignition switch (hereinafter referred to as IG switch) 52 operation signal, and the like are input. The ECU 50 controls the driving of the fuel injection valve 17 based on various input signals and also controls the throttle actuator 14a.
The secondary air supply pump 33, the exhaust side on / off valve 34, the intake side on / off valve 36, and the like are controlled. The ECU 50 is provided with a soak timer 51 for measuring the elapsed time after the engine is stopped.

In the engine 10, HC remains in the vicinity of the intake port such as the intake manifold 16 due to fuel leaking from the fuel injection valve 17 (oil tight leak), fuel blow back from the combustion chamber, fuel inflow from the PCV passage, and the like. The HC remains even after the 10 operation is stopped. If this residual HC is left unattended, floating HC in the vicinity of the intake port is sucked into the engine combustion chamber along with cranking at the next engine start, and is further discharged unburned. Therefore, in the present embodiment, air is forcibly injected near the intake port while the engine is stopped, thereby removing floating HC near the intake port, thereby suppressing HC discharge when starting the engine. Details will be described below.

FIG. 2 is a flowchart showing an air injection process performed while the engine is stopped. This process is performed as a function of the ECU 50. This air injection process is started by the ECU 50 when the time measured by the soak timer 51 reaches a predetermined time. Specifically, the air injection process is started after the engine is stopped (ignition OFF).
Implemented when minutes have passed. In practice, however, the fuel injection valve 1
It is desirable that the air injection process be performed after the time when the oil-tight leak of No. 7 is eliminated and the floating HC concentration in the vicinity of the intake port is predicted to be stable. In this embodiment, when 6 hours have passed since the engine stopped. This air injection process is performed.

In FIG. 2, in step S101, ECU power ON processing is performed to turn on the power supply system of various devices related to air injection, and in subsequent steps S102 to S104, air injection execution conditions are determined. That is, in step S102, it is determined whether or not the engine water temperature is within a predetermined temperature range (for example, 0 to 60 ° C.).
In 103, it is determined whether or not the intake air temperature is within a predetermined temperature range (for example, 0 to 60 ° C.), and in step S104, it is determined whether or not air injection is not performed after the engine is stopped. As an implementation condition of air injection, it is possible to use that the engine oil temperature and the transmission oil temperature are within a predetermined temperature range in addition to the above. If each of the execution conditions is satisfied, the process proceeds to step S105, and the exhaust side on-off valve 34 is turned off.
(Closed), the intake side on-off valve 36 is turned on (opened), the throttle opening is controlled to a predetermined opening, and the secondary air supply pump 33 is turned on (driven) to perform air injection. That is, when the engine water temperature or the intake air temperature is equal to or higher than a predetermined value, the temperature in the vicinity of the intake port (intake manifold 16) is high, and it is considered that the high boiling point HC is filled in the vicinity of the intake port. Therefore, air injection is prohibited until the temperature in the vicinity of the intake port decreases and the high boiling point HC is liquefied.

In such a case, the secondary air from the secondary air supply pump 33 is supplied to the intake manifold 16.
The air flow is generated in the intake pipe 11, the intake manifold 16, and the like. As a result, the floating HC in the vicinity of the intake port is sent toward the upstream portion of the intake pipe 11, and H
It is adsorbed by the C adsorbent 31. At this time, the pump 33 is driven while the air flow rate of the secondary air supply pump 33 is limited so that the HC does not blow through the HC adsorbent 31. In other words, if the secondary air supply pump 33 is driven at the same air flow rate as when supplying secondary air to the exhaust side, HC will blow through the HC adsorbent 31, so that the air flow rate is slower than when supplying the exhaust side. . Specifically, the air flow rate is limited by intermittently driving the secondary air supply pump 33 or limiting the drive voltage or drive current of the secondary air supply pump 33.

Thereafter, in step S106, it is determined whether or not a predetermined time (for example, about 1 minute) has elapsed after the start of air injection. If the predetermined time has not elapsed, the present processing is terminated. If the predetermined time has elapsed, the process proceeds to step S107, and the ECU power is turned off.

After HC adsorption to the HC adsorbent 31, the adsorbed HC is separated from the flow of intake air during operation of the engine 10 and is sucked into the combustion chamber together with the intake air. Then, it is used for combustion together with the fuel injected from the fuel injection valve 17. Thereby, the H of the HC adsorbent 31
C adsorption capacity is restored. When the engine is started, the adsorbed HC of the HC adsorbent 31 is not yet released at the cranking stage, and the released HC is released before the start of combustion.
Is not inhaled into the combustion chamber.

FIG. 3 is a flowchart showing a secondary air supply process performed during engine operation, and this process is performed by the ECU 50 at predetermined intervals.

In FIG. 3, first, in step S201, it is determined whether or not the IG switch 52 is ON, and the process proceeds to the subsequent step S202 on condition that the IG switch is ON. In step S202, the starting water temperature is within a predetermined temperature range (for example, 0 to 60 ° C.).
In step S203, it is determined whether or not the elapsed time from the start is within a predetermined time range (for example, within one minute). And step S2
If the conditions of 02 and S203 are both satisfied, the process proceeds to step S204, the exhaust side on-off valve 34 is turned on (opened), the intake side on-off valve 36 is turned off (closed), and the secondary air supply pump 33 is turned on (drive). ) To supply the secondary air to the exhaust side.

Thereafter, in step S205, it is determined whether or not a predetermined time (for example, about 1 minute) has elapsed after the supply of secondary air. If the predetermined time has not elapsed, the present processing is terminated. If the predetermined time has elapsed, the process proceeds to step S206, and the exhaust side on-off valve 34 is set to OF.
F (closed), intake side on-off valve 36 is turned off (closed), and secondary air supply pump 33 is turned on
By setting to FF (driving stop), the supply of the secondary air to the exhaust side is terminated.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

By injecting air while the engine is stopped, hydrocarbons floating in the vicinity of the intake port are efficiently adsorbed by the HC adsorbent 31. Further, when the engine is operating, high boiling point HC is mixed and floats in the vicinity of the intake port due to fuel blow-back from the combustion chamber, etc., but in this embodiment, the HC adsorbent 31 is a place where the HC does not float (air cleaner). 12), the floating HC is not adsorbed to the HC adsorbent 31 during engine operation, and a decrease in HC adsorption performance can be suppressed. With the above,
At the next engine start, floating HC near the intake port with cranking
Can be prevented from being sucked into the combustion chamber and discharged without being burned. As a result, the HC emission amount can be effectively reduced. In the present embodiment, in particular, the secondary air supply pump 33 can be used as an air injection means, thereby preventing an increase in cost.

Since the air inlet is provided in the intake manifold 16, HC floating mainly in the vicinity of the intake port can be efficiently removed. If the air inlet is provided in the immediate vicinity of the throttle valve 14, the air may not flow upstream of the throttle and the floating HC may not be sufficiently removed. However, according to the above configuration, such an inconvenience is solved. Incidentally, the air inlet is connected to the surge tank 15 and the intake manifold 16.
It is thought that the structure installed in the downstream rather than 1/2 of the total volume of is desirable.

In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

In the above embodiment, the HC adsorbent 31 is disposed in the air cleaner 12 at the most upstream part of the intake pipe, but this configuration is changed. A configuration example as another embodiment is shown in FIGS. Hereinafter, the difference from FIG. 1 will be mainly described. In FIG. 4, an HC adsorbent 63 is provided in the bypass passage 61 in a configuration in which an ISC valve (idle speed control valve) 62 is provided in the bypass passage 61 provided in the intake pipe 11. In this configuration, when the secondary air supply pump 33 is driven and air is injected while the engine is stopped, the floating HC in the vicinity of the intake port flows through the bypass passage 61 and is adsorbed by the HC adsorbent 63. At this time, the throttle valve 14 is closed and the ISC valve 62 is opened to a predetermined opening. In the present embodiment, the use of the bypass passage 61 can prevent cost increase. When the engine is in operation, the adsorbed HC of the HC adsorbent 63 is released by opening the ISC valve 62.

Further, in FIG. 5, a fuel evaporative gas discharge suppression device is provided for suppressing the fuel evaporative gas (evaporative gas) generated in the fuel tank 71 from being discharged to the outside. That is, one end of a conduit 72 is connected to the fuel tank 71, and a canister 73 is connected to the other end of the conduit 72. The canister 73 stores a large number of adsorbents made of activated carbon, for example, for adsorbing fuel evaporative gas generated in the fuel tank 71. The canister 73 is connected to the intake pipe 11 through a purge pipe 74, and an electromagnetically driven purge control valve 75 is provided in the middle of the purge pipe 74. The amount of gas discharged to the intake pipe 11 (purge gas amount) is controlled by a purge control valve 75. In this configuration, when the secondary air supply pump 33 is driven and air is injected while the engine is stopped, the floating HC in the vicinity of the intake port flows through the purge pipe 74 and is adsorbed by the canister 73. At this time, the throttle valve 14 is closed and the purge control valve 75 is opened to a predetermined opening degree.
In the present embodiment, the canister 33 can be used as a hydrocarbon adsorbent, thereby preventing an increase in cost. During engine operation, the purge control valve 75 is opened according to the engine operation state at that time, and the HC adsorbed on the canister 73 is
Is released.

An air injection passage in the intake manifold 16 (intake air passage 35 in the configuration of FIG. 1)
Instead of the configuration in which air is injected via the air intake, a configuration in which air is directly injected into the intake manifold 16 may be employed. In this case, an air pump or the like may be provided directly on the outer wall of the intake manifold 16.

A fuel injection valve with air assist, which is adapted to atomize the fuel spray by ejecting air from the tip of the fuel injection valve, is applied to the secondary air supply pump 33 to the assist air outlet for the fuel injection valve. It is also possible to adopt a configuration in which air is injected. In this case, since air is injected from the tip of the fuel injection valve (assist air outlet), even if a lot of HC remains in the vicinity of the intake port, it can be efficiently removed. Moreover, cost can be prevented by diverting the existing assist air ejection port.

When the engine is stopped, the vehicle door lock is released or the door is opened,
It is good also as a structure which implements air injection by the secondary air supply pump 33 at the time of the detection. In order to reliably prevent HC discharge during cranking, it is desirable to remove floating HC in the vicinity of the intake port immediately before the start of cranking. According to the present embodiment, removal of floating HC is preferably performed. Can do. Thereby, HC discharge at the time of cranking can be prevented more reliably.

An air pump different from the secondary air supply pump 33 can be used as the air injection means (air flow generation source).

It is a block diagram which shows the engine control system in embodiment of invention. It is a flowchart which shows an air injection process. It is a flowchart which shows a secondary air supply process. It is a block diagram which shows the HC discharge | emission amount reducing device in another example. It is a block diagram which shows the HC discharge | emission amount reducing device in another example.

Explanation of symbols

10 ... Engine,
11 ... Intake pipe,
14 ... Throttle valve,
15 ... Surge tank,
16 ... intake manifold,
17 ... Fuel injection valve,
31 ... HC adsorbent,
32 ... exhaust air passage,
33 ... Secondary air supply pump,
34 ... Exhaust side opening / closing valve,
35 ... Intake air passage,
36 ... intake side on-off valve,
50 ... ECU,
61 ... Bypass passage,
62 ... ISC valve,
63 ... HC adsorbent,
71 ... Fuel tank,
73 ... canister,
74 ... Purge piping,
75 ... Purge control valve.

Claims (17)

An air injecting means for injecting air into or near the intake port in the intake passage of the internal combustion engine, and a hydrocarbon adsorbent for adsorbing hydrocarbons, the hydrocarbon adsorbent leading to the vicinity of the intake port and An internal combustion engine having a configuration installed in a place where hydrocarbons having a high boiling point do not float, wherein the air injection means is driven to generate the air flow while the operation of the internal combustion engine is stopped. Hydrocarbon emission reduction device. 2. The hydrocarbon discharge amount of the internal combustion engine according to claim 1, wherein an air injection passage is connected to or near the intake port of the internal combustion engine, and air is injected into the air injection passage by the air injection means. Reduction device. In a multi-cylinder internal combustion engine, a branch portion branched from an intake manifold portion,
3. The hydrocarbon emission reduction device for an internal combustion engine according to claim 1, wherein air injection is performed by the air injection means. A fuel injection valve with air assist, which is adapted to atomize fuel spray by ejecting air from the tip of the fuel injection valve, is applied to the assist air outlet for the fuel injection valve by the air injection means. The hydrocarbon emission reduction device for an internal combustion engine according to claim 1 or 2, wherein the injection is configured to perform injection. The hydrocarbon of the internal combustion engine according to any one of claims 1 to 4, wherein an installation location of the hydrocarbon adsorbent is a location where an air flow to the engine combustion chamber is generated during operation of the internal combustion engine. Emission reduction device. The hydrocarbon emission reduction device for an internal combustion engine according to any one of claims 1 to 4, wherein the hydrocarbon adsorbent is disposed in an air cleaner provided in a most upstream portion of the intake passage. 7. The hydrocarbon emission reduction device for an internal combustion engine according to claim 6, wherein when air is injected near the intake port by the air injection means, a throttle valve provided in the intake passage is opened to a predetermined opening. A fuel evaporative emission control device having a canister for temporarily adsorbing fuel evaporative gas generated in a fuel tank and discharging the fuel adsorbed on the canister to the intake passage through a purge passage during engine operation 5. The internal combustion engine according to claim 1, wherein the canister is used as the hydrocarbon adsorbent, and the intake passage and the canister are in communication with each other while the operation of the internal combustion engine is stopped. Equipment for reducing hydrocarbon emissions. In the fuel evaporative emission control device, the purge passage is provided with a purge control valve for opening or closing the passage, and during operation of the internal combustion engine, the purge control valve is opened according to the state of the engine operation at that time. The hydrocarbon emission reduction device for an internal combustion engine according to claim 8, wherein the hydrocarbon adsorbed on the gas is released. A bypass passage for bypassing a throttle valve provided in the intake passage and an idle speed control valve provided in the bypass passage, wherein the hydrocarbon adsorbent is provided in the middle of the bypass passage. Item 5. A hydrocarbon emission reduction device for an internal combustion engine according to any one of Items 1 to 4. The secondary air supply pump, which is applied to an internal combustion engine comprising a catalyst for purifying exhaust gas discharged from the internal combustion engine and a secondary air supply pump for supplying secondary air to the catalyst 11. The internal combustion engine according to claim 1, wherein the secondary air supplied from the secondary air supply pump is injected into the vicinity of the intake port. Equipment for reducing hydrocarbon emissions. The secondary air supply pump is connected to an exhaust passage of the internal combustion engine via an exhaust side air passage, and is connected to an intake passage of the internal combustion engine via an intake side air passage, and the exhaust side air passage, the intake side Each of the air passages is opened and closed by an open / close control valve, and when the air is injected near the intake port using the secondary air supply pump, the exhaust side air passage is closed by the open / close control valve, and the intake air The apparatus for reducing hydrocarbon emissions of an internal combustion engine according to claim 11, wherein the side air passage is opened. The amount of hydrocarbon emissions from the internal combustion engine according to any one of claims 1 to 12, wherein an air flow rate generated by the air injection means is limited to a flow rate at which hydrocarbons do not blow through the hydrocarbon adsorbent. Reduction device. The internal combustion engine according to any one of claims 1 to 13, wherein after the operation of the internal combustion engine is stopped, the air injection by the air injection means is performed after a predetermined soak time has elapsed. Hydrocarbon emission reduction device. 15. The release of a door lock or the opening of a door of a vehicle equipped with the internal combustion engine is detected when the internal combustion engine is stopped, and air injection by the air injection means is performed at the time of detection. The hydrocarbon emission reduction device for an internal combustion engine according to any one of the above. The hydrocarbon of an internal combustion engine according to any one of claims 1 to 15, wherein an engine temperature is detected and air injection by the air injection means is prohibited when the detected engine temperature is equal to or higher than a predetermined temperature. Emission reduction device. An air flow source for forcibly generating an air flow in an intake passage of an internal combustion engine and a hydrocarbon adsorbent for adsorbing hydrocarbons, and hydrocarbons near the intake port float The hydrocarbon adsorbent is installed downstream of the air flow generated by the air flow generation source, and the air flow is generated by the air flow generation source while the internal combustion engine is stopped. A hydrocarbon emission reduction device for an internal combustion engine characterized by the above.

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