JP2012087746A - Vaporized fuel processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vaporized fuel processing device capable of simplifying a constitution.SOLUTION: This vaporized fuel processing device 10 includes a canister 14 for sucking vaporized fuel, a tank passage 20 for communicating the canister 14 with a fuel tank 12, a purge passage 22 for communicating the canister 14 with an intake passage 18 of an engine 16, an atmospheric passage 24 for communicating the canister 14 with the atmosphere, a purge control valve 26 arranged in the purge passage 22, and an ECU 28 for controlling the purge control valve 26. The atmospheric passage 24 includes a low temperature passage 42 opened in the air of the low temperature, a high temperature passage 44 opened in the air of the high temperature, and a three-way valve 46 for selectively opening-closing the low temperature passage 42 and the high temperature passage 44. The ECU 28 switches the three-way valve 46 so as to open the high temperature passage 44 and close the low temperature passage 42 when opening the purge control valve 26, and also switches the three-way valve so as to close the high temperature passage 44 and open the low temperature passage 42 when closing the purge control valve 26.

Description

  The present invention relates to an evaporative fuel processing apparatus that adsorbs evaporative fuel generated mainly in a fuel tank of a vehicle such as an automobile with a canister and purges the adsorbed evaporative fuel into an intake passage of an internal combustion engine (engine).

As a conventional example of this type of fuel vapor processing apparatus, there is one described in Patent Document 1, for example. An evaporative fuel processing apparatus of a conventional example (Patent Document 1) will be described. FIG. 4 is a block diagram showing the fuel vapor processing apparatus.
As shown in FIG. 4, the evaporative fuel processing apparatus includes a first passage 116 and a second passage 118 that communicate a canister 112 that adsorbs and holds evaporative fuel to a fuel tank 114 and an intake passage 104 of the internal combustion engine 102, respectively. Yes. The canister 112 is provided with a third passage 120 that communicates with one end, and the other end of the third passage 120 communicates with a portion near the exhaust passage 106 of the internal combustion engine 102 and a fifth passage 124 that communicates with the atmosphere. It is branched and provided. A temperature adjusting unit 126 that adjusts the purge air introduced into the canister 112 to a predetermined temperature by mixing high-temperature air through the fourth passage 122 and low-temperature air through the fifth passage 124 is provided at the branch portion. According to this fuel vapor processing apparatus, when introducing purge air into the canister 112, high temperature air is guided to the fourth passage 122 and low temperature air is guided to the fifth passage 124, and the temperature of the high temperature air and the low temperature air is adjusted. The mixture is mixed by the unit 126 to be adjusted to a predetermined temperature and introduced into the canister 112 from the third passage 120.

JP-A-4-353256

  In the conventional evaporative fuel processing apparatus, the open end of the fourth passage 122 is communicated with the vicinity of the exhaust passage 106 of the internal combustion engine 102 (in the vicinity of the outside of the exhaust manifold according to FIG. 1 of Patent Document 1). Yes. The high temperature air guided from the fourth passage 122 and the low temperature air guided from the fifth passage 124 are mixed by the temperature adjusting unit 126 and adjusted to a predetermined temperature. Therefore, there has been a problem that the configuration has to be complicated. In addition, if it consists of a structure which mixes high temperature air and low temperature air, the high temperature air in patent document 1 is high temperature air which is difficult to introduce into the canister 112 as it is, and it is necessary to lower temperature by mixing with low temperature air. It is thought that there is.

  The problem to be solved by the present invention is to provide an evaporative fuel processing apparatus capable of simplifying the configuration.

The above-mentioned problem can be solved by an evaporative fuel processing apparatus having the gist of the configuration described in the claims.
That is, according to the evaporated fuel processing apparatus of claim 1, a canister that adsorbs evaporated fuel, a tank passage that communicates the canister and the fuel tank, a purge passage that communicates the canister and the intake passage of the internal combustion engine, An evaporative fuel processing apparatus comprising an atmospheric passage communicating the canister and the atmosphere, a purge control valve provided in the purge passage, and a control means for controlling the purge control valve, wherein the atmospheric passage is in low-temperature air And a passage switching means for selectively opening and closing the low-temperature passage and the high-temperature passage, and the control means includes the passage switching means. When the purge control valve is opened, the high temperature passage is opened and the low temperature passage is closed, and when the purge control valve is closed, the high temperature passage is closed and the low temperature passage is opened. It is intended to switch. With this configuration, when the purge control valve is opened, that is, when purging, high-temperature air is introduced into the canister via the high-temperature passage, so that the canister desorption performance can be improved. Further, when the purge control valve is closed, that is, when not purged, the canister can be opened to the low temperature air through the low temperature passage. Therefore, unlike the above-mentioned Patent Document 1, it is not necessary to mix high-temperature air and low-temperature air to adjust to a predetermined temperature, and the configuration can be simplified. The term “hot air” as used in the present specification refers to high-temperature air having a temperature that does not need to be adjusted by mixing with low-temperature air and that does not cause any problem even if introduced into the canister as it is.

  According to the evaporated fuel processing apparatus of the second aspect, the high temperature passage is opened to high temperature air in the vicinity of the exhaust pipe of the internal combustion engine. If comprised in this way, the exhaust heat of an internal combustion engine can be utilized effectively.

  According to the evaporated fuel processing apparatus of the third aspect, the passage switching means is a three-way valve. With this configuration, the low temperature passage and the high temperature passage can be selectively opened and closed by one three-way valve.

  Further, according to the evaporated fuel processing apparatus of the fourth aspect, the fuel component concentration detecting means for detecting the concentration of the fuel component in the purge gas purged from the canister to the intake passage of the internal combustion engine through the purge passage. And the control means reduces the opening of the purge control valve when the concentration of the fuel component detected by the fuel component concentration detection means is higher than a predetermined concentration, and the concentration of the fuel component is less than the predetermined concentration. In this case, the opening degree of the purge control valve is increased. With this configuration, when the concentration of the fuel component in the purge gas is higher than a predetermined concentration, that is, when the amount of vapor adsorbed is large or when the amount of vapor generated from the tank is large, the opening of the purge control valve becomes small. By making the purge gas amount small, it is possible to prevent drivability from deteriorating due to a large amount of purge gas having a high fuel component concentration being sucked into the intake passage. In addition, when the concentration of the fuel component in the purge gas is less than the predetermined concentration, the opening of the purge control valve is increased, so that a large amount of purge gas can be efficiently purged.

It is a block diagram which shows the evaporative fuel processing apparatus concerning Embodiment 1. FIG. It is a flowchart which shows the process which concerns on control of a three-way valve. It is a block diagram which shows the evaporative fuel processing apparatus concerning Embodiment 2. It is a block diagram which shows the evaporative fuel processing apparatus concerning a prior art example.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[Embodiment 1]
Embodiment 1 of the present invention will be described. FIG. 1 is a configuration diagram showing an evaporative fuel processing apparatus.
As shown in FIG. 1, the evaporative fuel processing device 10 adsorbs evaporative fuel generated in a fuel tank 12 of a vehicle such as an automobile by a canister 14, and the adsorbed evaporative fuel is an intake passage 18 of an internal combustion engine (engine) 16. Purge to The canister 14 contains an adsorbent (not shown) made of activated carbon. The adsorbent can adsorb evaporated fuel (vapor) generated in the fuel tank 12 and can remove fuel components such as hydrocarbon (HC) in the vapor. The canister 14 and the fuel tank 12 are communicated with each other via a tank passage 20. The canister 14 and the intake passage 18 are communicated with each other via a purge passage 22. Further, the canister 14 and the atmosphere communicate with each other through an atmospheric passage 24. The atmospheric passage 24 will be described in detail later.

  A purge control valve 26 is provided in the purge passage 22. The purge control valve 26 is a vacuum switching valve (VSV) that adjusts the amount of air containing the fuel component of the evaporated fuel (purge gas amount) flowing through the purge passage 22, and is controlled by an electronic control unit (hereinafter referred to as “ECU”) 28. Be controlled. The ECU 28 corresponds to “control means” in this specification. In addition, the code | symbol in FIG. 1, 30 is a throttle valve, 32 is an exhaust passage. The exhaust passage 32 includes an exhaust manifold 33, an upstream catalyst 34, a downstream catalyst 36, an exhaust pipe 38, and the like.

  The canister 14 introduces the evaporated fuel generated in the fuel tank 12 from the tank passage 20 and adsorbs it on the adsorbent. Further, the purge control valve 26 is controlled by the ECU 28 in accordance with the operating state of the engine 16. When the purge control valve 26 is opened (corresponding to purging), intake negative pressure generated in the intake passage 18 acts on the canister 14 via the purge passage 22. As a result, the fuel component of the evaporated fuel adsorbed by the adsorbent of the canister 14 is desorbed from the adsorbent together with the air introduced into the canister 14 via the atmospheric passage 24, thereby becoming purge gas and entering the intake passage 18. Purged. Further, the fuel component of the purge gas purged into the intake passage 18 is burned by the engine 16.

  Next, the atmospheric passage 24 will be described. The atmosphere passage 24 includes a communication passage 40, a low temperature passage 42, a high temperature passage 44, and a three-way valve 46. The communication passage 40 communicates the canister 14 and the three-way valve 46. Further, one end of the low temperature passage 42 is connected to the three-way valve 46, and the other end is opened to air at normal temperature, that is, low temperature. The high-temperature passage 44 has one end connected to the three-way valve 46 and the other end opened to high-temperature air near the upper side of the exhaust pipe 38. Note that the high-temperature air in the vicinity of the upper side of the exhaust pipe 38 is air that does not cause any trouble even if it is introduced into the canister 14 as it is.

  As used herein, “hot air” refers to high-temperature air that does not need to be mixed with low-temperature air to adjust the temperature and that does not cause any problems even if introduced into the canister 14 as it is. . For example, air having a temperature lower than a heat resistant temperature of a component (for example, a sealing member such as an O-ring) having the lowest heat resistant temperature among the components constituting the canister 14 is referred to as “high temperature air”. Generally, the heat resistance temperature of the seal member in the case of the canister 14 arranged in the engine room is about 120 ° C., and the heat resistance temperature of the seal member in the case of the canister 14 arranged under the floor of the vehicle is about 120 ° C. 90 ° C. In this way, the “hot air” is high-temperature air having a predetermined temperature lower than the heat-resistant temperature of the component having the lowest heat-resistant temperature among the constituent members constituting the canister 14, so that the canister 14 is purged. When it is introduced into the can, the detachment performance of the canister 14 can be improved without affecting the parts having the lowest heat-resistant temperature.

  The three-way valve 46 is an electromagnetic valve that selectively opens and closes the low temperature passage 42 and the high temperature passage 44, and is controlled by the ECU 28. That is, the ECU 28 switches the three-way valve 46 to the open state of the high-temperature passage when the purge control valve 26 is opened (when purging), and the three-way valve when the purge control valve 26 is closed (when not purged). 46 is switched to a low temperature passage open state. Specifically, the three-way valve 46 opens the high temperature passage 44 and closes the low temperature passage 42 when the high temperature passage is open, and closes the high temperature passage 44 and opens the low temperature passage 42 when the low temperature passage is open. The three-way valve 46 corresponds to “passage switching means” in this specification.

Next, processing related to the control of the three-way valve 46 executed by the ECU 28 will be described. FIG. 2 is a flowchart showing processing relating to control of the three-way valve.
As shown in FIG. 2, the ECU 28 determines whether or not the purge is being performed in step S1, that is, whether or not the purge control valve 26 is in an open state. If the determination is affirmative (YES), the three-way valve 46 is determined in step S2. Is switched to a high temperature passage open state. As a result, when the purge control valve 26 is opened, that is, purged, high-temperature air near the upper side of the exhaust pipe 38 is introduced into the canister 14 via the high-temperature passage 44 and the communication passage 40. Thereby, since the cooling of the adsorbent (activated carbon) due to the heat of vaporization of the canister 14 at the time of purging can be suppressed, the desorption performance of the canister 14 at the time of purging can be improved. If the determination in step S1 is negative (NO), the three-way valve 46 is switched to the low temperature passage open state in step S3. Thereby, the canister 14 can be opened to the low temperature air through the communication passage 40 and the low temperature passage 42 at the time of non-purge. For this reason, during the non-purge, it is possible to reliably prevent the air containing the evaporated fuel from being blown from the canister 14 into the high-temperature air. The non-purge time corresponds to, for example, when the engine 16 is stopped, parked, or refueled.

  According to the fuel vapor processing apparatus 10 described above, when the purge control valve 26 is opened, that is, at the time of purging, high-temperature air is introduced into the canister 14 via the high-temperature passage 44 and the communication passage 40, so that the canister 14 is detached. The performance can be improved. Further, when the purge control valve 26 is closed, that is, when not purged, the canister 14 can be opened to the low temperature air through the communication passage 40 and the low temperature passage 42. Therefore, unlike the above-mentioned Patent Document 1, it is not necessary to mix high-temperature air and low-temperature air to adjust to a predetermined temperature, and the configuration can be simplified.

  Further, in the case of the non-purge, in Patent Document 1, there is a risk that air containing evaporated fuel from the canister into the high-temperature air may be blown out. Therefore, it is possible to reliably prevent the air containing evaporated fuel from being blown into the air and to ensure safety.

  The high temperature passage 44 is open to high temperature air in the vicinity of the exhaust pipe 38 of the engine 16. Therefore, the exhaust heat of the engine 16 can be used effectively.

  A three-way valve 46 is used as a passage switching means for selectively opening and closing the low temperature passage 42 and the high temperature passage 44. Therefore, the low temperature passage 42 and the high temperature passage 44 can be selectively opened and closed by one three-way valve 46.

[Embodiment 2]
A second embodiment of the present invention will be described. Since the present embodiment is obtained by changing a part of the first embodiment, the changed portion will be described and redundant description will be omitted. FIG. 3 is a block diagram showing the fuel vapor processing apparatus. Note that hydrocarbon (HC) and other components can be considered as fuel components contained in the evaporated fuel, but since HC accounts for the majority, HC will be described as a fuel component for convenience.
As shown in FIG. 3, in this embodiment, an HC sensor 48 for detecting the concentration of the fuel component (HC) in the purge gas is provided in the purge passage 22 in the first embodiment. A detection signal from the HC sensor 48 is input to the ECU 28. The HC sensor 48 corresponds to “fuel component concentration detection means” in this specification.

  The ECU 28 calculates the concentration of the fuel component from the concentration of HC detected by the HC sensor 48. If the concentration of the fuel component is higher than a predetermined concentration, the ECU 28 decreases the opening of the purge control valve 26, and When the fuel component concentration is less than the predetermined concentration, the opening degree of the purge control valve 26 is controlled so that the opening degree of the purge control valve 26 is increased.

  Therefore, when the concentration of the fuel component in the purge gas is higher than a predetermined concentration, that is, when the amount of vapor adsorbed is large or when the amount of vapor generated from the fuel tank 12 is large, the opening of the purge control valve 26 becomes small. By making the amount small, it is possible to prevent deterioration of drivability due to a large amount of purge gas having a high fuel component concentration being sucked into the intake passage 18 into the engine 16. In addition, when the concentration of the fuel component in the purge gas is less than the predetermined concentration, the opening degree of the purge control valve 26 is increased, so that a large amount of purge gas can be efficiently purged.

  The present invention is not limited to the above-described embodiment, and modifications can be made without departing from the gist of the present invention. For example, in each of the embodiments described above, the open end of the high temperature passage 44 is opened in the high temperature air in the vicinity of the upper side of the exhaust pipe 38. However, the open end of the high temperature passage 44 may be introduced even if high temperature air is introduced into the canister as it is. If it is in high-temperature air at a temperature that does not cause any trouble, it may be opened to a portion other than the vicinity of the upper side of the exhaust pipe 38.

  In the second embodiment, the HC sensor 48 provided in the purge passage 22 is used as the fuel component concentration detecting means for detecting the fuel component concentration in the purge gas, and the fuel is detected from the HC concentration detected by the HC sensor 48. Although the concentration of the component is calculated, the oxygen sensor provided in the exhaust passage 32 is used as the fuel component concentration detecting means, and the concentration of the fuel component is calculated from the oxygen concentration Ox detected by the oxygen sensor. Also good.

  Further, the atmospheric passage 24 in each embodiment has one end connected to the canister 14 and the other end connected to the canister 14 at one end connected to the canister 14 at the other end, and the other end exhausted. A high-temperature passage opened in high-temperature air in the vicinity of the upper side of the pipe 38 and a pair of on-off valves (electromagnetic valves) disposed in the low-temperature passage and the high-temperature passage and opened and closed by the ECU reciprocally. You can also In this case, the pair of on-off valves corresponds to “passage switching means” in the present specification.

DESCRIPTION OF SYMBOLS 10 ... Evaporative fuel processing apparatus 12 ... Fuel tank 14 ... Canister 16 ... 18 of engine (internal combustion engine) 16 ... Intake passage 20 ... Tank passage 22 ... Purge passage 24 ... Atmospheric passage 26 ... Purge control valve 28 ... ECU (control means)
38 ... Exhaust pipe 42 ... Low temperature passage 44 ... High temperature passage 46 ... Three-way valve (passage switching means)
48 ... HC sensor (fuel component concentration detection means)
50 ... Air passage 52 ... Low temperature passage 54 ... High temperature passage

Claims (4)

A canister that adsorbs evaporated fuel;
A tank passage communicating the canister and the fuel tank;
A purge passage communicating the canister and the intake passage of the internal combustion engine;
An atmospheric passage communicating the canister and the atmosphere;
A purge control valve provided in the purge passage;
An evaporative fuel processing apparatus comprising: control means for controlling the purge control valve;
The atmospheric passage includes a low-temperature passage opened in low-temperature air, a high-temperature passage opened in high-temperature air, and passage switching means for selectively opening and closing the low-temperature passage and the high-temperature passage. ,
The control means switches the passage switching means to open the high temperature passage and close the low temperature passage when the purge control valve is opened, and closes the high temperature passage when the purge control valve is closed. Switching to open the low-temperature passage. An evaporative fuel processing apparatus, characterized in that: It is an evaporative fuel processing apparatus of Claim 1, Comprising:
The evaporative fuel processing apparatus, wherein the high-temperature passage is opened to high-temperature air in the vicinity of an exhaust pipe of the internal combustion engine. The evaporative fuel processing apparatus according to claim 1 or 2,
The fuel vapor processing apparatus, wherein the passage switching means is a three-way valve. It is an evaporative fuel processing apparatus as described in any one of Claims 1-3,
Fuel component concentration detection means for detecting the concentration of fuel component in purge gas purged from the canister to the intake passage of the internal combustion engine through the purge passage;
The control means reduces the opening of the purge control valve when the fuel component concentration detected by the fuel component concentration detection means is higher than a predetermined concentration, and the fuel component concentration is less than the predetermined concentration. When it is thin, the evaporated fuel processing apparatus is characterized in that the opening of the purge control valve is increased.

Images