JP2005030324A - Evaporated fuel treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporated fuel treatment device capable of purging evaporated fuel of relatively large volume to an intake system even when a turbocharger is operated. <P>SOLUTION: A canister 12 to store evaporated fuel generated in a fuel tank 10 is connected to an intake pipe 2 of an engine 1 via a first purge passage 13. The first purge passage is connected to the intake pipe 2 on the upstream side of a turbocharger 5 via a passage 15, a jet pump 17, and a passage 16. Air pressurized by the turbocharger 5 is fed to the jet pump 17. The jet pump 17 comprises a nozzle 21 from which pressurized air is ejected, and a casing 22 surrounding the nozzle 21 with a space therebetween. The evaporated fuel is purged to the intake pipe 2 via the passages 15 and 16 by gas flow generated by ejecting pressurized air from the nozzle 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an evaporative fuel processing apparatus that temporarily stores evaporative fuel generated in a fuel tank and supplies the evaporative fuel to an intake system of an internal combustion engine in a timely manner, and more particularly to an evaporative fuel in an intake system of an internal combustion engine with a supercharger. It relates to what is supplied.

  Patent Document 1 discloses an evaporated fuel processing apparatus that supplies evaporated fuel to an intake pipe of an internal combustion engine with a supercharger. In an internal combustion engine with a supercharger, when the supercharger is operated, the intake pipe internal pressure downstream of the supercharger becomes higher than atmospheric pressure, so a normal purge for supplying evaporated fuel downstream of the throttle valve The evaporative fuel stored in the canister cannot be sufficiently purged into the intake pipe only by the passage.

  Therefore, in the apparatus disclosed in Patent Document 1, a passage connecting the intake pipe to the upstream side and the downstream side of the supercharger (compressor), and a connection passage having a venturi portion provided in the middle thereof, is provided. A purge passage connected to a canister for storing evaporated fuel is opened in the venturi section. This device is intended to supply evaporated fuel to the intake pipe from the canister through the connection passage during operation of the supercharger by the negative pressure generated in the venturi section.

Japanese Utility Model Publication No. 63-162965

  However, it has been confirmed by experiments that a sufficient negative pressure cannot be obtained only by providing a venturi section in the connection passage, and that the evaporated fuel is hardly supplied to the intake pipe or is supplied in a small amount. Has been.

  The present invention has been made in view of this point, and an object of the present invention is to provide an evaporative fuel processing apparatus capable of purging a relatively large amount of evaporative fuel into an intake system even during operation of a supercharger.

  In order to achieve the above object, the invention described in claim 1 is directed to a fuel tank (10), a canister (12) for temporarily storing evaporated fuel generated in the fuel tank (10), and the fuel tank (10). ) And the canister (12), a charge passage (11) connecting the intake pipe (2) of the internal combustion engine (1) having a supercharger (5) and the canister (12). In the evaporative fuel processing apparatus, which includes a purge passage (13) and a purge control valve (14) that is provided in the first purge passage (13) and adjusts the flow rate of the purge gas, the first purge passage (13) A second purge passage (15, 16) for connecting a downstream side of the purge control valve (14) and an upstream side of the supercharger (5) of the intake pipe (2); The dice provided in the purge passage (15, 16) And a supercharged air supply passage (18) for supplying air pressurized by the supercharger (5) to the jet pump (17), the jet pump (17) A nozzle (21) for ejecting pressurized air and a casing (22) surrounding the nozzle (21) with a gap (23) between the nozzle (21) and the gap (23) Constitutes a part of the second purge passage (15, 16).

The nozzle (21) of the jet pump is slidably attached to the casing. The higher the pressure of the pressurized air, the more the position of the nozzle outlet (21a) is the jet pump. It is desirable to be configured to be away from the exhaust port.
More specifically, the nozzle (21) has a flange (21b), and the flange (21b) and the casing (22) define a pressure chamber (25), and the flange (21b) On the opposite side to the pressure chamber (25), a spring (27) is inserted between the casing (22). The spring (27) biases the nozzle (21) toward the exhaust port of the jet pump (17). The pressure chamber (25) is supplied with air pressurized by the supercharger (5).

  According to the first aspect of the present invention, when air pressurized by the supercharger is ejected from the nozzle of the jet pump, a flow is generated by the ejected air flow due to the viscosity of the ejected air, and negative pressure is generated. . As a result, the air-fuel mixture containing the evaporated fuel is sucked from the upstream side of the second purge passage without being supplied to the upstream side of the second purge passage, and is discharged from the jet pump. Supplied upstream of the supercharger of the pipe. As a result, the evaporated fuel can be purged from the canister to the intake pipe even during operation of the supercharger, and the evaporated fuel can be prevented from staying in the canister.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an evaporative fuel processing apparatus and an intake system of an internal combustion engine according to an embodiment of the present invention. An internal combustion engine (hereinafter referred to as an “engine”) 1 has an intake pipe 2, and an air cleaner 4, a supercharger 5, an intercooler 6, and a throttle valve 3 are provided in that order from the upstream side. . The supercharger 5 includes a turbine that is rotationally driven by the energy of exhaust gas, and a compressor that is driven by the turbine and pressurizes the intake air. The supercharger 5 discharges the pressurized air to the downstream side of the intake pipe 2.

The fuel tank 10 is connected to a canister 12 through a charge passage 11, and the canister 12 is connected to the downstream side of the throttle valve 3 in the intake pipe 2 through a first purge passage 313.
The canister 12 contains activated carbon for adsorbing the evaporated fuel in the fuel tank 10. An air passage 12a is connected to the canister 12, and the canister 12 communicates with the atmosphere through the air passage 12a.

  A purge control valve 14 is provided in the first purge passage 13. The purge control valve 14 is an electromagnetic valve configured such that the flow rate can be continuously controlled by changing the on-off duty ratio (the opening degree of the control valve) of the control signal. It is controlled by an electronic control unit (not shown).

  The first purge passage 13 branches into a passage 15 on the downstream side of the purge control valve 14, and the passage 15 is connected to the upstream side of the supercharger 5 in the intake pipe 2 via the jet pump 17 and the passage 16. Has been. That is, the passages 15 and 16 constitute a second purge passage. Air that has been pressurized by the supercharger 5 is supplied to the jet pump 17 via the supercharged air supply passage 18. If there is resistance on the exhaust side of the jet pump 17, the function of the jet pump 17 will not be fully exerted, so the passage 16 connected to the exhaust side of the jet pump 17 is thick and configured to extend linearly. Yes.

The fuel tank 10, the charge passage 11, the canister 12, the first purge passage 13, the purge control valve 14, the passages 15 and 16 (second purge passage), the jet pump 17, and the supercharged air supply passage 18 are used to process the evaporated fuel. The device is configured.
If a large amount of evaporated fuel is generated during refueling of the fuel tank 10, the evaporated fuel is stored in the canister 12. In a predetermined operation state of the engine 1, the duty control of the purge control valve 14 is performed, and an appropriate amount of evaporated fuel is supplied from the canister 12 to the intake pipe 2.

  FIG. 2 is a cross-sectional view showing the configuration of the jet pump 17. The jet pump 17 is connected to a supercharged air supply passage 18, and has a cylindrical nozzle 21 that ejects pressurized air, and a casing 22 that surrounds the nozzle 21 with a gap 23 between the nozzle 21. Consists of. The nozzle 21 has a nozzle hole 21a for ejecting pressurized air. The casing 22 is provided with an intake port 22a to which the passage 15 is connected and an exhaust port 22b to which the passage 16 is connected.

  When air pressurized by the supercharger 5 is ejected from the nozzle 21 of the jet pump 17 (see arrow A), the flow from the suction port 22a to the exhaust port 22b by the flow of the ejected air due to the viscosity of the ejected air (arrow B) Reference) is generated, and negative pressure is generated. As a result, the air-fuel mixture containing the evaporated fuel is sucked from the passage 15 through the suction port 22a without flowing the pressurized air into the passage 15, and the passage through the exhaust port 22b together with the pressurized air. 16 is discharged. Then, the air-fuel mixture discharged from the jet pump 17 is supplied to the upstream side of the supercharger 5 in the intake pipe 2. As a result, the evaporated fuel can be purged from the canister 12 to the intake pipe 2 even during operation of the supercharger, and the evaporated fuel can be prevented from staying in the canister 12.

  FIG. 3 is a diagram showing the range of the intake pipe absolute pressure (intake pipe pressure downstream of the throttle valve 3) PBA in which the evaporated fuel can be purged, corresponding to the purge flow rate QP. The range indicated by the broken line in this figure corresponds to the case where the second purge passage including the passages 15 and 16 and the jet pump 17 are not provided, and the range indicated by the solid line corresponds to the present embodiment. As described above, according to the present embodiment, the range of the intake pipe absolute pressure PBA that can be purged is greatly expanded, and the evaporated fuel adsorbed by the canister 12 can be reliably purged.

  FIG. 4 is a cross-sectional view showing a configuration of a modified example of the jet pump 17 shown in FIG. In this figure, the nozzle 21 is provided with a flange 21 b, and the casing 22 is provided with a partition wall 24. A pressure chamber 25 is defined between the casing 22 and the nozzle 21 by the flange 21 b and the partition wall 24. The pressure chamber 25 is provided with a pressurized air supply port 26 so that the air pressurized by the supercharger 5 flows into the pressure chamber 25 through the pressurized air supply port 26. Yes. In addition, a spring 27 is inserted between the flange 21b and the casing 22 to urge the flange 21b in the left direction in the drawing (in a direction in which the nozzle 21 approaches the exhaust port 22b). Further, the nozzle 21 is slidably inserted into the casing 22.

  The partition 24, the flange 21 b, the pressure chamber 25, the pressurized air supply port 26, and the spring 27 constitute a focal length variable mechanism. As shown in FIG. 4, the focal length f is a distance from the tip of the nozzle 21 to the inlet of the exhaust port 22b. According to the focal length variable mechanism, the higher the pressure in the pressure chamber 25, the farther the nozzle 21 is from the exhaust port 22b and the longer the focal length f is.

FIG. 5 is a diagram showing the relationship between the focal length f and the flow rate QG of the generated gas flow. In lines L1, L2, and L3, the air pressures ejected from the nozzle 21 are 148 kPa, 128 kPa, and 108 kPa, respectively. This corresponds to the case. The focal length (hereinafter referred to as “optimal focal length”) fOPT at which the generated gas flow rate QG is maximum shows a tendency to increase as the pressure of the pressurized air increases. That is, the line L4 in FIG. 5 shows the change in the optimum focal length fOPT with respect to the change in air pressure.
Therefore, it is possible to always ensure the maximum purge flow rate by changing the focal length f according to the pressure of the pressurized air by the above-described focal length variable mechanism.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, the variable focal length mechanism is configured such that the position of the nozzle 21 can be moved by an electric motor, and the intake pipe internal pressure upstream of the throttle valve 3 on the downstream side of the supercharger 5 or the downstream side of the throttle valve 3. It is also possible to detect the intake pipe absolute pressure PBA, drive the electric motor in accordance with the detected pressure, and variably control the focal length f.

It is a figure which shows the structure of the evaporative fuel processing apparatus concerning one Embodiment of this invention. It is sectional drawing which shows the structure of the jet pump shown in FIG. It is a figure which shows the relationship between an intake pipe internal pressure (PBA) and purge flow volume (QP). It is sectional drawing which shows the structure of the modification of a jet pump. It is a figure which shows the relationship between a focal distance (f) and a production gas flow rate (QG).

Explanation of symbols

1 Internal combustion engine 2 Intake pipe 3 Throttle valve 5 Supercharger 10 Fuel tank 11 Charge passage 12 Canister 13 First purge passage 15 passage (second purge passage)
16 passage (second purge passage)
17 Jet pump 18 Supercharged air supply passage

Claims (1)

A fuel tank, a canister for temporarily storing evaporated fuel generated in the fuel tank, a charge passage connecting the fuel tank and the canister, an intake pipe of an internal combustion engine including a supercharger, and the canister In an evaporative fuel processing apparatus comprising: a first purge passage to be connected; and a purge control valve that is provided in the first purge passage and adjusts the flow rate of the purge gas.
A second purge passage connecting the downstream side of the purge control valve of the first purge passage and the upstream side of the supercharger of the intake pipe;
A jet pump provided in the second purge passage;
A supercharged air supply passage for supplying air pressurized by the supercharger to the jet pump;
The jet pump includes a nozzle that ejects the pressurized air, and a casing that surrounds the nozzle with a gap between the nozzle and the gap forms a part of the second purge passage. An evaporative fuel processing apparatus characterized by the above.

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