JPH06147034A - Evaporative fuel control device - Google Patents

Abstract

(57) [Summary] [Object] The present invention can supply not only the evaporated fuel to the intake passage of the internal combustion engine but also the evaporated fuel to the exhaust passage, thereby reducing the purge load of the intake system. As a result, the influence on the internal combustion engine side can be reduced, the influence on the air-fuel ratio control can be reduced, and moreover, a large amount of evaporated fuel can be supplied to the intake system and the exhaust system as a whole. Has an aim. For this reason, an air cut valve that has one end connected to the middle of the intake purge passage between the canister and the purge valve and the other end connected to the exhaust passage of the internal combustion engine is provided with an air cut valve that opens and closes the passage in the middle of the exhaust purge passage. The air control valve is provided with an air passage for applying negative pressure to the intake pipe to the air cut valve to open and close the air cut valve, and an air control valve is provided in the middle of the air passage to connect the air control valve to the control unit. The air cut valve is controlled to open and close by turning on and off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor control system, and more particularly to a fuel vapor control system which separates vaporized fuel adsorbed and held in a canister and supplies it to an intake passage and also supplies it to an exhaust passage.

[0002]

2. Description of the Related Art In a vehicle, evaporated fuel leaking into the atmosphere from a fuel tank, a float chamber of a carburetor, etc., contains a large amount of hydrocarbons (HC), which is one of the causes of air pollution. In addition, various techniques for preventing this are known because they also lead to fuel loss. As a typical example thereof, there is an evaporative fuel control device that causes a canister containing an adsorbent such as activated carbon to separate (purge) the evaporated fuel in a fuel tank when the internal combustion engine is in operation and supply the evaporated fuel to the internal combustion engine.

As the evaporative fuel control device, there is an actual 5
Some are disclosed in Japanese Patent Publication No. 7-31553. The purge flow control device of the evaporative gas recovery device disclosed in this publication is provided in the exhaust purge passage for guiding the evaporative fuel collected in the canister to the exhaust passage and the exhaust purge passage, and the secondary combustion is performed. It has a valve device for opening the exhaust purge passage and guiding the vaporized and trapped fuel in one direction from the canister toward the exhaust passage even when the engine is warmed up to the end.

[0004]

By the way, in the conventional evaporated fuel control system, as shown in FIG. 3, a part of the intake passage 106 downstream of the throttle valve 110 is formed by the fuel tank 122 and the intake system of the internal combustion engine 102. Forming surge tank 108
The inside is communicated with an intake purge passage 114, and the adsorbent containing the evaporated fuel generated in the fuel tank 122 while the internal combustion engine 102 is stopped is adsorbed and held in the intake purge passage 114 while the internal combustion engine 102 is operating. Is provided with a canister 116 that releases (purges) the evaporated fuel that has been adsorbed and held by the introduction of fresh air from the air introduction port 130 and supplies it to the intake passage 106.
A purge valve 118 is provided in the intake purge passage 114 between the intake passage 106 and the intake passage 106.

The vaporized fuel purged from the canister 116 by the negative pressure of the intake pipe generated in the surge tank 108 is supplied into the surge tank 108, and the amount of vaporized fuel is regulated by the purge valve 118. The purge valve 118 is controlled to be opened / closed by a control unit 132 that inputs each operating state of the internal combustion engine 102.

That is, the purge of the evaporated fuel from the canister 116 is performed by using the intake pipe negative pressure located on the downstream side of the throttle valve 110 arranged in the intake system of the internal combustion engine 102.

As a result, the hydrocarbon (HC) adsorbed in the canister has a great influence on the air-fuel ratio, which adversely affects drivability and exhaust gas performance, which is disadvantageous in practical use.

Further, in recent years, the evaporative regulation (especially in the United States) has become very strict, and a large amount of purging is required in the exhaust gas test, and the purging can be carried out to the extent that the evaporative regulation can be satisfied. It has been earnestly desired to realize an evaporated fuel control device capable of reducing adverse effects on the atmosphere.

[0009]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention eliminates the evaporated fuel generated in the fuel tank in the middle of an intake purge passage communicating the inside of the fuel tank with the intake passage of the internal combustion engine. A canister for adsorbing and holding and releasing the evaporated fuel adsorbed and held by the introduction of fresh air to supply it to the intake passage is provided with a purge valve in the middle of the intake purge passage between the canister and the intake passage to control opening / closing of the purge valve. In the evaporative fuel control device provided with a control unit, an exhaust purge passage is provided, one end of which is connected to the middle of the intake purge passage between the canister and the purge valve and the other end of which is connected to the exhaust passage of the internal combustion engine. An air cut valve that opens and closes the passage is installed in the middle of the air cut valve to open and close the air cut valve. An air passage for applying negative pressure to the intake pipe is provided in the valve, and an air control valve is provided in the middle of the air passage. This air control valve is connected to the control unit to turn the air control valve on and off to open and close the air cut valve. It is characterized in that it is configured to control.

[0010]

According to the invention as described above, when the evaporated fuel is supplied to the exhaust passage, the control unit controls the air control valve to be turned on and the air cut valve to be opened so that the evaporated fuel from the canister is removed. It is supplied to the exhaust passage through the exhaust purging passage.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, 2 is an internal combustion engine mounted on a vehicle (not shown), 4 is an intake manifold, 6 is an intake passage, 8 is a surge tank, 10 is a throttle valve, and 12 is an evaporated fuel control device. The evaporated fuel control device 12 includes an intake purge passage 14, a canister 16, and a purge valve (VSV) 18.

The evaporation passage 20 constituting a part of the intake purge passage 14 has one end communicating with the evaporated fuel retaining portion 24 of the fuel tank 22 and the other end opening into the upper portion of the canister 16. .

The purge passage 26, which constitutes a part of the intake purge passage 14, has one end opening parallel to the purge passage 20 in the upper portion of the canister 16, and
The other end is communicated with the purge port 28 of the surge tank 8 downstream of the throttle valve 10.

The canister 16 accommodates an adsorbent such as activated carbon that adsorbs and holds evaporated fuel from the fuel tank 22 side, and introduces fresh air from the lower air introduction port 30 according to the operating state of the internal combustion engine 2. The vaporized fuel adsorbed and held by the adsorbent is released (purged) and flowed to the purge passage 26 side.

The purge valve 18 is provided in the middle of the purge passage 26. As a result, the purge passage 26 becomes the first purge passage 26-1 and the second purge passage 26-.
The purge valve 18 connects and disconnects the first purge passage 26-1 and the second purge passage 26-2.

The purge valve 18 is turned on by a control unit 32 for inputting the operating state of the internal combustion engine 2 from the air amount and the like within a predetermined range depending on, for example, the engine speed and the intake pipe negative pressure.

An exhaust purge passage 36, one end of which communicates with the exhaust passage 34 of the internal combustion engine 2 and the other end of which communicates with the exhaust passage 34 of the internal combustion engine 2, is provided in the intake purge passage 14 between the canister 16 and the purge valve 18. An air cut valve 38 that opens and closes the passage is provided in the middle of the air passage 36, an air passage 40 that applies negative pressure to the intake pipe to the air cut valve 38 to open and close the air cut valve 38 is provided, and an air control valve is provided in the middle of the air passage 40. 42 is provided, the air control valve 42 is connected to the control unit 32, and the air control valve 42 is turned on / off to control the opening / closing of the air cut valve 38.

More specifically, one end side of the exhaust purge passage 36 is provided in the intake purge passage 14 between the canister 16 and the purge valve 18, that is, in the middle of the first purge passage 26-1, and the exhaust purge is provided. The other end of the passage 36 is provided so as to communicate with the exhaust passage 34 of the internal combustion engine 2, that is, the exhaust passage 34 upstream of the catalyst 44.

In the middle of the exhaust purge passage 36,
An air cut valve 38 that opens and closes the passage from the upstream side and a check valve 46 that is a one-way valve that allows only the flow to the exhaust passage 34 side are sequentially provided, and the air cut valve 38 is opened and closed to open and close the air cut valve 38. Pressure chamber 38
One end side of the air passage 40 is provided so as to communicate with a in order to apply a negative pressure to the intake pipe, and the other end side of the air passage 40 is provided so as to communicate with the surge tank 8.

The check valve 46 is provided in the exhaust passage 34.
It is opened and closed by an upstream and downstream pressure difference utilizing the exhaust pulsation generated inside.

Further, an air control valve 42 is provided in the middle of the air passage 40, and the air control valve 42 is connected to the control unit 32 to turn the air control valve 42 on and off to control the opening and closing of the air cut valve 38. To do.

At this time, the opening / closing control of the purge valve 18 and the air control valve 42 by the control unit 32 is performed simultaneously, for example.

Next, the operation will be described.

When the internal combustion engine 2 is driven and the water temperature, intake air temperature, or other operating condition satisfies a predetermined condition,
While the control unit 32 opens the purge valve 18,
The air control valve 42 is opened.

When the purge valve 18 is opened, the first purge passage 26-1 and the second purge passage 26-2 are in communication with each other, and fresh air is introduced from the air introduction port 30 so that the adsorbent in the canister 16 adsorbs and holds it. The evaporated fuel is separated (purged) and supplied to the surge tank 8.

When the air control valve 42 is opened, the intake pipe pressure from the surge tank 8 acts on the pressure chamber 38a of the air cut valve 38 through the air passage 40, and the air cut valve 38 is opened.

Evaporative fuel is supplied to the exhaust passage 34 from the middle of the first purge passage 26-1 through the exhaust purge passage 36.

As a result, the intake passage 6 of the internal combustion engine 2 is
Not only to supply the evaporated fuel to the exhaust passage 3
4, it is possible to supply the evaporated fuel to 4 as well, the burden of purging of the intake system can be reduced, and the influence on the internal combustion engine 2 side can be reduced, which is advantageous in terms of service life and cost, and the air-fuel ratio The influence on the control can be reduced, which is advantageous in controlling the exhaust gas.

Even if the purging load of the intake system is reduced, a large amount of evaporated fuel can be supplied to the intake system and the exhaust system as a whole, which makes it possible to sufficiently meet the stricter evaporation regulations in recent years. In addition to being able to deal with it, it is possible to reduce the adverse effect on the atmosphere, which is practically advantageous.

Further, when the evaporated fuel is supplied, it is possible to control so as to simultaneously supply the amount making use of the characteristics of each of the intake system and the exhaust system, so that the cleaning effect of the exhaust gas and the evaporated fuel control are significantly improved. It plays.

FIG. 2 shows a second embodiment of the present invention. The portions having the same functions as those in the first embodiment will be described with the same reference numerals.

The feature of the second embodiment resides in that the air pump 50 is arranged in the middle of the exhaust purge passage 36.

That is, an air cut valve 38 and a check valve 46 are sequentially arranged in the exhaust purge passage 36 from the upstream side, and an air pump is provided in the exhaust purge passage 36 upstream of the air cut valve 38. Fifty
Is provided.

Thus, when the supply of the evaporated fuel to the exhaust system is insufficient, the evaporated fuel can be forcibly supplied by the air pump 50, and the supply control of the evaporated fuel to the exhaust system can be surely performed. At the same time, the check valve 46 can be operated to prevent backflow from the exhaust side.

Further, as in the case of the first embodiment described above, not only the evaporated fuel can be supplied to the intake passage 6 of the internal combustion engine 2, but also the evaporated fuel can be surely supplied to the exhaust passage 34 at the same time. The load on the intake system purge can be reduced, the influence on the internal combustion engine 2 side can be reduced, which is advantageous in terms of service life and cost, and the influence on the air-fuel ratio control can be reduced. It is advantageous in controlling exhaust gas.

Furthermore, even if the purging load of the intake system is reduced, a large amount of evaporated fuel can be supplied to the intake system and the exhaust system as a whole. It is practically advantageous because it can sufficiently cope with the stricter evaporative regulation and can reduce the adverse effect on the atmosphere.

Furthermore, when the evaporated fuel is supplied, as in the case of the first embodiment described above, it is possible to control so as to simultaneously supply an amount that makes the best use of the features of the intake system and the exhaust system. It is very effective in cleaning gas and controlling evaporated fuel.

The present invention is not limited to the first and second embodiments described above, and various application modifications are possible.

For example, in the first and second embodiments of the present invention, the control unit controls the opening and closing of the purge valve and the air control valve at the same time. However, the purge valve and the air control valve are controlled according to the operating conditions and other conditions. The control valve and the opening / closing control may be individually performed, and the evaporated fuel may be supplied by the independent control of the intake system and the exhaust system.

[0041]

As described in detail above, according to the present invention, an exhaust purge passage having one end communicating with the exhaust passage of the internal combustion engine and the other end communicating with the exhaust passage of the internal combustion engine is provided in the middle of the intake purge passage between the canister and the purge valve. An air cut valve that opens and closes the passage is provided in the middle of the purge passage, an air passage that applies negative pressure to the intake pipe is provided to the air cut valve to open and close the air cut valve, and an air control valve is provided in the middle of the air passage. Since the control valve is connected to the control unit and the air control valve is turned on and off to control the opening and closing of the air cut valve, not only the evaporated fuel is supplied to the intake passage of the internal combustion engine, but also the exhaust passage is evaporated. Fuel can be supplied, the burden of purging of the intake system can be reduced, the impact on the internal combustion engine side can be reduced, and the service life and cost can be reduced. With advantageously it can be a small impact on the air-fuel ratio control. In addition, even if the purging load of the intake system is reduced, a large amount of evaporated fuel can be supplied to the intake system and the exhaust system as a whole, so that it is possible to sufficiently cope with the stricter evaporation regulations in recent years. At the same time, adverse effects on the atmosphere can be reduced, which is practically advantageous. Further, when the evaporated fuel is supplied, it can be controlled so as to supply the amount that makes use of the features of each of the intake system and the exhaust system, so that it is extremely effective in cleaning the exhaust gas and controlling the evaporated fuel. .

[Brief description of drawings]

FIG. 1 is a schematic diagram of an evaporated fuel control device showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an evaporated fuel control device showing a second embodiment of the present invention.

FIG. 3 is a schematic diagram of an evaporated fuel control device showing a conventional technique of the present invention.

[Explanation of symbols]

 2 Internal Combustion Engine 6 Intake Passage 8 Surge Tank 10 Throttle Valve 12 Evaporative Fuel Control Device 14 Intake Purge Passage 16 Canister 18 Purge Valve (VSV) 20 Evaporation Passage 22 Fuel Tank 24 Evaporative Fuel Reservoir 26 Purge Passage 26-1 First Purge Passage 26 -2 2nd purge passage 30 Atmosphere introduction port 32 Control part 34 Exhaust passage 36 Exhaust purge passage 38 Air cut valve 40 Air passage 42 Air control valve 44 Catalyst 46 Check valve

Claims (1)

[Claims] 1. An evaporated fuel generated in the fuel tank is adsorbed and held in the middle of an intake purge passage that connects the inside of the fuel tank with an intake passage of an internal combustion engine, and the adsorbed fuel that is adsorbed and held is released by the introduction of fresh air. In a fuel vapor control device having a canister for supplying to the intake passage, a purge valve provided in the intake purge passage between the canister and the intake passage, and a control unit for controlling opening and closing of the purge valve, An exhaust purging passage, one end of which is connected to the middle of the intake purging passage and the other end of which is connected to the exhaust passage of the internal combustion engine, is provided with an air cut valve that opens and closes the passage in the middle of the exhaust purging passage to open and close the air cut valve. In order to ensure that the air cut valve is provided with an air passage for applying negative pressure to the intake pipe, An evaporative fuel control device characterized in that an air control valve is provided on the way, and the air control valve is connected to the control unit to turn the air control valve on and off to control the opening and closing of the air cut valve.