JP2009180092A - Evaporated-fuel treating device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporated-fuel treating device of an internal combustion engine capable of properly preventing a dilution air regulating valve from being seized. <P>SOLUTION: This evaporated-fuel treating device is applied to a multi-cylinder internal combustion engine having intake control valves disposed in their respective intake passages for cylinders, and used for treating the evaporated fuel produced in a fuel tank. Specifically, the evaporated-fuel treating device comprises a purge passage for guiding a purge gas to branch passages through a communication part allowing the branch passages to communicate with each other, a dilute air supply passage for guiding the dilution air for diluting the purge gas, and the dilution air regulating valve for regulating a dilution air quantity supplied into the purge passage. A forced-driving means forcibly openably drives the dilution air regulating valve in an operating area in which no explosion is expected to occur in the internal combustion engine. Consequently, the dilution air regulating valve can be properly prevented from being seized while suppressing a variation in the rotation of the internal combustion engine. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an evaporated fuel processing apparatus for an internal combustion engine that processes evaporated fuel generated in a fuel tank.

  This is applied to an internal combustion engine in which a throttle valve is arranged in each of the independent intake pipes provided for each cylinder, and the independent intake pipes are connected to all the cylinders downstream of each throttle valve by a common communication pipe. An evaporative fuel processing apparatus is known in which a purge pipe for introducing purge gas containing evaporated fuel generated in a fuel tank is connected to the communication pipe. Further, in Patent Document 1, an assist air type fuel injection valve is provided in each of the independent intake passages provided for each cylinder, and a purge passage is connected to the assist air passage for sending air to the fuel injection valve. An evaporative fuel processing device is described in which the air is supplied to each independent intake passage via a fuel injection valve together with assist air for diluting the air (hereinafter referred to as “diluted air” or simply “air”).

JP-A-7-189820

  In the apparatus described in Patent Document 1 described above, the throttle valve is preferentially varied for the convenience of control over the intake air amount, and is also referred to as a valve for adjusting dilution air (hereinafter referred to as “dilution air adjustment valve”). ) Was set to a fixed opening, or the operating range and operating frequency were limited. For this reason, the dilution air adjustment valve has not been operated for a long time, and the dilution air adjustment valve may stick.

  The present invention has been made to solve the above-described problems, and is capable of preventing the dilution air regulating valve from sticking by operating the dilution air regulating valve at an appropriate timing. An object is to provide an apparatus.

  In one aspect of the present invention, an evaporative fuel processing device for an internal combustion engine includes an intake passage having a branch passage branched for each cylinder, and a throttle valve provided in each branch passage and capable of adjusting an intake air flow rate. A purge that is applied to a multi-cylinder internal combustion engine that has a fuel gas generated in a fuel tank and that is connected to each branch passage at a position downstream of the throttle valve. A dilution air supply passage connected to the purge passage and connected to the purge passage for guiding dilution air for diluting the purge gas; and a dilution air adjustment provided on the dilution air supply passage for adjusting the amount of dilution air supplied to the purge passage And a forcible drive means for forcibly opening and closing the dilution air adjustment valve in an operation region where no explosion is expected to occur in the internal combustion engine.

  The above-described evaporated fuel processing device for an internal combustion engine is applied to a multi-cylinder internal combustion engine in which an intake control valve is provided in each of the intake passages for each cylinder, and is suitable for processing evaporated fuel generated in a fuel tank. Used. Specifically, an evaporative fuel processing apparatus for an internal combustion engine includes a purge passage that guides purge gas to each branch passage through a communication portion that communicates each branch passage with each other, and a dilution air supply passage that guides dilution air that dilutes the purge gas. And a dilution air adjustment valve for adjusting the amount of dilution air supplied to the purge passage. Then, the forcible drive means forcibly opens and closes the dilution air adjustment valve in an operation region where no explosion in the internal combustion engine is predicted to occur. As a result, it is possible to prevent the dilution air regulating valve from sticking while suppressing the rotational fluctuation of the internal combustion engine.

  Preferably, in the fuel vapor processing apparatus for an internal combustion engine, the forcible drive means forcibly opens and closes the dilution air adjustment valve before starting the internal combustion engine.

  Preferably, the forcible drive means forcibly drives the dilution air adjustment valve to open and close when the internal combustion engine is stopped.

  More preferably, the forcible drive means forcibly drives the dilution air adjustment valve to open and close during fuel cut in the internal combustion engine. Thereby, the frequency which performs a forced drive can be increased and it becomes possible to prevent sticking of a dilution air regulating valve more reliably.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Device configuration]
FIG. 1 shows a main part of an internal combustion engine 1 to which an evaporated fuel processing apparatus according to this embodiment is applied.

  The internal combustion engine 1 is configured as an in-line four-cylinder spark ignition internal combustion engine (multi-cylinder internal combustion engine) in which four cylinders 2 are arranged in one direction. Each cylinder 2 is provided with an intake passage 3 and an exhaust passage 4. The intake passage 3 has a branch passage 3a branched for each cylinder 2 and a surge tank 3b to which each branch passage 3a is connected. An air cleaner 5 for air filtration is provided upstream of the surge tank 3b, and an air flow meter capable of detecting the intake air flow rate in the intake passage 3 downstream of the air cleaner 5 and upstream of the branch position where the branch passage 3a branches. 6 is provided. Each branch passage 3 a is provided with one throttle valve 7 whose opening degree can be adjusted so that the intake air flow rate can be adjusted, and one injector 8 that injects fuel downstream of the throttle valve 7. . Each throttle valve 7 is attached to a valve shaft 7a extending through each branch passage 3a, and the valve shaft 7a is rotationally driven by an actuator 7b. Thereby, each throttle valve 7 functions as a so-called independent throttle valve.

  As shown also in FIG. 2, on the downstream side of each throttle valve 7, in order to alleviate the pressure difference between the respective branch passages 3a, there is a balance in which each branch passage 3a communicates with each other at a position downstream of the throttle valve 7. A passage 9 is provided. A purge passage 10 for guiding purge gas containing vapor (evaporated fuel) generated in the fuel tank 20 is connected to the branch passage 3 a so as to face the balance passage 9. The purge passage 10 includes a communication portion 10 a that communicates the branch passages 3 a with each other at a position downstream of the throttle valve 7. The passage area of the communication portion 10 a is configured to be smaller than the passage area of the balance passage 9. Has been. The absolute size of the passage area of the communication portion 10a may be set as appropriate, and the passage area is preferably set such that no pulsation occurs in the communication portion 10a or very small pulsations are generated.

  As shown in FIG. 1, the purge passage 10 is connected to a fuel tank 20 through a canister 11 that adsorbs evaporated fuel. The canister 11 is a well-known one that adsorbs the evaporated fuel introduced from the fuel tank 20 with activated carbon incorporated while introducing air through an air introduction pipe 11a that is open to the atmosphere. A dilution air supply passage 12 for introducing air (dilution air) into the purge passage 10 is connected between the canister 11 and the communication portion 10a. The other end of the dilution air supply passage 12 is connected to the surge tank 3b. The dilution air supply passage 12 is provided with a dilution air adjustment valve 13 that can adjust the amount of dilution air supplied to the purge passage 10. The opening degree of the dilution air adjustment valve 13 is controlled by an ECU (Engine Control Unit) 50 as indicated by a broken line arrow in FIG. When the dilution air is guided to the purge passage 10 in the dilution air supply passage 12, the purge gas flowing through the purge passage 10 is diluted by the dilution air.

  On the downstream side of the connection position between the dilution air supply passage 12 and the purge passage 10, a mixing promoting portion 10b that promotes mixing of the purge gas and the dilution air is provided. Specifically, the mixing promoting portion 10b is configured by meandering the purge passage 10.

  Each element of the internal combustion engine 1 is controlled by an ECU (Engine Control Unit) 50. The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). The ECU 50 mainly functions as a forced drive means in the present invention and controls the dilution air adjustment valve 13. The ECU 50 also controls other components of the internal combustion engine 1, but description of portions not particularly related to the present embodiment is omitted.

  According to the above embodiment, since the communication portion 10a having a smaller passage area than the balance passage 9 is provided, the pressure of the communication portion 10a is higher than that of each branch passage 3a due to the flow resistance of the communication portion 10a. As a result, a steady flow as shown by the arrow in FIG. 2 is formed. Since the purge gas is introduced into each branch passage 3a using the flow, the evaporated fuel can be processed without being released to the atmosphere. Since the purge gas introduced into each branch passage 3a is diluted with the diluted air introduced through the dilution air supply passage 12, a sudden change in the air-fuel ratio due to introduction of a high-concentration purge gas into the branch passage 3a can be suppressed.

  Further, the position where the diluted air is taken out by the diluted air supply passage 12 is located downstream of the air flow meter 6, and the purge gas is diluted by the air measured by the air flow meter 6. Therefore, fuel injection is performed in anticipation of the amount of air used for dilution. The amount can be determined, and fluctuations in the air-fuel ratio can be further suppressed. Moreover, since the air is taken out from the surge tank 3b, the supply of the diluted air by the diluted air supply passage 12 can be prevented from being affected by the intake pulsation.

[Control method]
Next, a control method performed by the ECU 50 for the dilution air adjustment valve 13 will be described. In the present embodiment, the ECU 50 forcibly drives the dilution air adjustment valve 13 to open and close in an operation region where the explosion in the internal combustion engine 1 is predicted not to occur for the purpose of preventing the dilution air adjustment valve 13 from sticking. The reason for performing such control is as follows.

  When the intake air amount to the internal combustion engine 1 is controlled, basically, the opening degree of the throttle valve 7 is adjusted, and the opening degree of the dilution air adjustment valve 13 is hardly adjusted. This is because, when cooperative control of both the throttle valve 7 and the dilution air adjustment valve 13 is performed, hunting or the like may occur in the control. Specifically, the dilution air adjustment valve 13 is set to a fixed opening degree or has an operation frequency and an operation range considerably limited as compared with the throttle valve 7 in order to perform an operation specialized for purge gas dilution. ing. If the operation frequency, operation range, etc. of the dilution air adjustment valve 13 are limited in this way, the dilution air adjustment valve 13 may not operate for a long time, and as a result, the dilution air adjustment valve 13 may stick. is there.

  Therefore, in the present embodiment, the ECU 50 forcibly opens and closes the dilution air adjustment valve 13 in order to prevent the dilution air adjustment valve 13 from sticking. Specifically, the ECU 50 forcibly drives the dilution air adjustment valve 13 in an operation region where it is predicted that no explosion occurs in the internal combustion engine 1. This is for suppressing rotational fluctuations (torque fluctuations) of the internal combustion engine 1 caused by forcibly driving the dilution air adjustment valve 13.

  Below, the control example which ECU50 performs with respect to the dilution air adjustment valve 13 is demonstrated.

(First control example)
In the first control example, the ECU 50 forcibly opens and closes the dilution air adjustment valve 13 before starting the internal combustion engine 1. Specifically, the ECU 50 forcibly drives the dilution air adjustment valve 13 when the ignition is on and before the starter is turned on, or when the ignition is on and not cranking. For example, the ECU 50 controls the dilution air adjustment valve 13 from fully open to fully closed, or controls the dilution air adjustment valve 13 from fully closed to fully open to fully closed, or the dilution air adjustment valve 13 from fully closed to fully open to the original. The dilution air adjustment valve 13 is forcibly driven by controlling the opening to the opening (the opening at that time). Thus, by forcibly driving the dilution air adjustment valve 13 before the internal combustion engine 1 is started, it is possible to prevent the dilution air adjustment valve 13 from sticking while suppressing the rotational fluctuation of the internal combustion engine 1.

(Second control example)
In the second control example, the ECU 50 forcibly opens and closes the dilution air adjustment valve 13 when the internal combustion engine 1 is stopped. Specifically, the ECU 50 has been in a state in which the ECU 50 and the dilution air adjustment valve 13 are operable after the ignition is turned off and a predetermined time has elapsed since the fuel injection / ignition was stopped. If it is present (ie, during main relay control), the dilution air adjustment valve 13 is forcibly driven. For example, the ECU 50 controls the dilution air adjustment valve 13 from fully open to fully closed, or controls the dilution air adjustment valve 13 from fully closed to fully open to fully closed, or the dilution air adjustment valve 13 from fully closed to fully open to the original. The dilution air adjustment valve 13 is forcibly driven by controlling the opening to the opening (the opening at that time). Thus, by forcibly driving the dilution air adjustment valve 13 when the internal combustion engine 1 is stopped, it is possible to prevent the dilution air adjustment valve 13 from sticking while suppressing fluctuations in the rotation of the internal combustion engine 1.

(Third control example)
In the third control example, the ECU 50 forcibly opens and closes the dilution air adjustment valve 13 during fuel cut in the internal combustion engine 1 (during fuel cut). That is, in the third control example, the dilution air adjustment valve 13 is forcibly driven during the operation of the internal combustion engine 1. For example, the ECU 50 controls the dilution air adjustment valve 13 to be fully closed → full open → the original opening (the opening at that time), or the dilution air adjustment valve 13 is fully opened → fully closed → the original opening. By doing so, the dilution air adjustment valve 13 is forcibly driven. In this way, by forcibly driving the dilution air adjustment valve 13 during the fuel cut, it is possible to prevent the dilution air adjustment valve 13 from sticking while suppressing the rotational fluctuation of the internal combustion engine 1. In the third control example, since the forced drive is performed during the operation of the internal combustion engine 1, the frequency of the forced drive can be increased as compared with the first and second control examples, and the dilution air adjustment is performed. It becomes possible to more reliably prevent the valve 13 from sticking.

(Modification)
In the first to third control examples described above, an example in which the dilution air adjustment valve 13 is forcibly driven before the internal combustion engine 1 is started, when the internal combustion engine 1 is stopped, or during fuel cut has been described. This is not limited. In another example, the dilution air adjustment valve 13 can be forcibly opened and closed before the internal combustion engine 1 is started, when the internal combustion engine 1 is stopped, and at least at any timing during fuel cut. That is, the controls in the first to third control examples may be executed in combination, or all the controls in the first to third control examples may be executed. Further, in the case where the control is performed in this way, the dilution air adjustment valve 13 may be forcibly driven only once per trip, and the above-described conditions (conditions such as before start, when stopped, during fuel cut) The dilution air adjustment valve 13 may be repeatedly forcibly driven every time the above is established.

The figure which showed the principal part of the internal combustion engine to which the evaporated fuel processing apparatus which concerns on this embodiment was applied. The cross-sectional schematic diagram which showed the cross section along the II-II line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Intake passage 3a Branch passage 3b Surge tank 7 Throttle valve 9 Balance passage 10 Purge passage 10a Communication portion 10b Mixing promotion portion 12 Dilution air supply passage 13 Dilution air adjustment valve 20 Fuel tank 50 ECU (Engine Control Unit)

Claims (4)

Applied to a multi-cylinder internal combustion engine having an intake passage having a branch passage branched for each cylinder and a throttle valve provided in each branch passage and capable of adjusting an intake air flow rate;
A purge passage for guiding purge gas containing evaporated fuel generated in the fuel tank to each branch passage through a communicating portion that communicates with each branch passage at a position downstream of the throttle valve;
A dilution air supply passage connected to the purge passage and leading to dilution air for diluting the purge gas;
A dilution air adjusting valve provided on the dilution air supply passage for adjusting the amount of dilution air supplied to the purge passage;
An evaporative fuel processing apparatus for an internal combustion engine, comprising: forcible driving means for forcibly opening and closing the dilution air adjustment valve in an operation region where no explosion is expected to occur in the internal combustion engine.   The evaporated fuel processing device for an internal combustion engine according to claim 1, wherein the forcible drive means forcibly opens and closes the dilution air adjustment valve before starting the internal combustion engine.   The evaporative fuel processing device for an internal combustion engine according to claim 1 or 2, wherein the forcible drive means forcibly opens and closes the dilution air adjustment valve when the internal combustion engine is stopped.   The evaporative fuel processing device for an internal combustion engine according to any one of claims 1 to 3, wherein the forcible drive means forcibly drives the dilution air adjustment valve to open and close during fuel cut in the internal combustion engine.

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