Patent Application
20050133097
The present invention relates to a detecting system or device for detecting an unexpected leakage of fuel evaporation gas mainly from a fuel tank constituting an automobile fuel supply device, and a method of detecting gas leakage by using the device.
Japanese Patent Publication (Kokai) No. 2001-12319 has disclosed a device for detecting leakage of fuel evaporation gas in a fuel tank constituting an automobile fuel supply device, i.e. a device for diagnosing leakage.
The device disclosed in Japanese Patent Publication (Kokai) No. 2001-12319 includes an air pump, a driving motor and surrounding pipes, thereby making the device complicated. In the device, the leakage is detected through an operation voltage of the driving motor of the air pump, thereby making it difficult to accurately detect the leakage. Further, it is necessary to start the air pump for detecting the leakage after an internal combustion engine is stopped, thereby wasting a battery and generating operation noise of the air pump after the internal combustion engine is stopped.
In view of the problems described above, an object of the present invention is to provide a device with a simple structure for precisely detecting an unexpected leakage of the fuel evaporation gas from the fuel tank.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In order to attain the objects described above, according to the present invention, a detecting system or device for detecting leakage of fuel evaporation gas in an automobile fuel supply device includes, as a fuel flow path system,
According to the present invention, the detecting device is constructed such that when the air flow switching valve switches to the communicating state, air is brought in the fuel tank through the first air flow line and the second air flow line with the excess fuel brought in the jet pump. The vent valve includes a fuel receiving tank communicating with the first air flow line and the sub-line; a float valve member disposed in the receiving tank for floating to block a communicating portion between the receiving tank and the first air flow line from a side of the receiving tank when fuel flows in the receiving tank; and an outflow portion for gradually discharging fuel in the fuel receiving tank to outside.
When the gas leakage is detected, the relief flow-path switching valve is operated to supply the excess fuel to the receiving tank of the vent valve. The outflow portion provided in the receiving tank is structured such that fuel in the receiving tank flows outside gradually. Accordingly, the float valve member is floated by the excess fuel to thereby block the communicating portion. At the same time, the air flow switching valve is operated to communicate the first air flow line with the second air flow line, and air is forcibly sent to the fuel tank by the jet pump. Then, the airflow switching valve is operated to block the communicating state between the first air flow line and the second air flow line. In this state, the inner pressure sensor detects the inner pressure of the fuel tank increased by the air forcibly sent therein. If the inner pressure is dropped quickly, it is determined that an unexpected gas leakage occurs.
In the detecting device described above, the first air flow line connecting the vent valve and the canister is utilized to forcibly send air in the fuel tank for detecting the gas leakage. Accordingly, it is not necessary to separately provide an air flow path for sending air in the fuel tank, so that a mechanism for detecting gas leakage can be appropriately provided to the fuel tank without impairing reliability of the fuel tank.
According to the present invention, the jet pump may include a discharge nozzle for the excess fuel disposed in a chamber connected to the second air flow line, and a discharge port formed at a front portion of the discharge nozzle in the chamber. A ratio of an inner diameter of the discharge nozzle to an inner diameter of the discharge port may be in a range between 1 to 3.5 and 1 to 5. When the ratio of the inner diameter of the discharge nozzle to the inner diameter of the discharge port is in the range, it is possible to effectively increase the inner pressure of the fuel tank in a short period of time.
According to the present invention, a method of detecting fuel evaporation gas leakage uses the fuel evaporation gas leakage detecting device described above in the automobile fuel supply system. The method includes the following (1)-(5) steps:
In the invention, the excess fuel is sent in the receiving tank of the vent valve through the operation of the relief flow path switching valve, so that the float valve member is floated to block the communicating portion. Then, the air flow switching valve is operated to communicate the first air flow line with the second air flow line, and air is forcibly sent to the fuel tank by the jet pump. Thereafter, the air flow switching valve is operated to return to the non-communicating state of the first air flow line and the second air flow line, so that the inner pressure of the fuel tank is held at an increased pressure. In this state, the inner pressure sensor detects the inner pressure of the fuel tank to be compared with an inner pressure under the normal condition, so that the unexpected gas leakage of the fuel tank is precisely detected.
Such a detecting method is preferably carried out when an automobile starts idling. In other words, when the automobile becomes an idling state, the excess fuel is supplied to the receiving tank of the vent valve to forcibly send air in the fuel tank.
When the automobile is running, fuel in the fuel tank swings and the inner pressure of the fuel tank tends to be unstable. Due to vibrations, the float valve member constituting the vent valve also tends to be unstable in blocking the communicating portion. Further, when the automobile is running, the internal combustion engine uses a larger quantity of fuel, thereby reducing the excess fuel to be sent to the jet pump. Accordingly, the leak detection is preferably limited only when the automobile is idling, thereby accurately detecting the leakage without the problems described above.
In the fuel evaporation gas leak detecting device in the automobile fuel supply device of the present invention, it is possible to detect the unexpected gas leakage from the fuel tank constituting the fuel supply device with the simple structure. In the method of detecting the fuel evaporation gas leakage, it is possible to precisely detect the unexpected gas leakage by using the device.
Hereunder, embodiments of the present invention will be explained with reference to the accompanying drawings. FIGS. 1 to 4 are views showing an automobile fuel supply device with a detecting device according to an embodiment of the present invention.
According to the present embodiment, a device for detecting fuel evaporation gas leakage in an automobile fuel supply device detects an unexpected leakage of gas mainly from a fuel tank 1 constituting a fuel supply device with a simple structure. A method of detecting the fuel evaporation gas leakage precisely determines whether gas is leaking or not by using the device.
The leakage detecting device includes a fuel flow system having:
The leakage detecting device also includes an air flow path system having:
An inner pressure sensor 12 is provided for detecting an inner pressure of the fuel tank 1. In the embodiment shown in the drawings, the fuel pump 2 disposed in the fuel tank 1 is activated to supply fuel to an internal combustion engine, specifically, a gasoline injector, via a main fuel line 14 from the fuel tank 1 storing fuel supplied through a hose 13. The relief line 3 is a flow path for relieving a part of fuel in the fuel tank 1 sucked by the fuel pump 2 as the excess fuel with a pressure controlled by a pressure regulator 15.
A third air flow line 17 provided with a check valve 16 is connected to the first air flow line 9. After the excess fuel is supplied to the receiving tank 8a constituting the vent valve 8 and the float valve member 8b is floated to block the vent valve 8, the jet pump 4 forcibly sends air to the fuel tank 1 to increase an inner pressure of the fuel tank 1 to open the check valve 16 for detecting the gas leakage (described later). The jet pump 4 is structured to send air to the fuel tank 1 through the first air flow line 9 and the second air flow line 10 in the communicating state by the air flow switching valve 11 by the excess fuel brought in the jet pump 4.
The vent valve 8 includes:
In the embodiment, the first air flow line 9 is connected to an upper portion of the receiving tank 8a. The sub-line 6 is connected to a side portion of the receiving tank 8a. The outflow portion 8d is disposed at a bottom of the receiving tank 8a. The receiving tank 8a is provided with an opening portion 8e, so that air in the fuel tank 1 is sent out to a canister 7 through the opening portion 8e when fuel is supplied to the fuel tank 1. When a level of fuel is increased, i.e. filling up the fuel tank 1 with fuel, the float valve member 8b is floated by fuel fed in the receiving tank 8a through the opening portion Be to thereby block the communicating portion 8c.
The outflow portion 8d may be a small hole passing through a bottom portion of the receiving tank 8a, or a one way valve for passing fuel only from the receiving tank 8a and not from the fuel tank 1 to the receiving tank 8a. The outflow portion 8d gradually discharges fuel in the receiving portion to the fuel tank 1. Accordingly, the float valve member 8b is floated to a position for blocking the communicating portion 8c by fuel, and is lowered after a certain period of time, so that the fuel tank 1 communicates with the canister 7 through the communicating portion 8c.
Normally, the excess fuel relieved through the jet pump 4 flows back to the fuel tank 1. The first air flow line 9 and the second air flow line 10 become a non-communicating state (
At the same time, the air flow switching valve 11 is operated to communicate the first air flow line 9 with the second air flow line 10, and air is forcibly sent to the fuel tank 1 by the action of the jet pump 4 (
The excess fuel fed into the receiving tank 8a of the vent valve 8 gradually flows to outside through the outflow portion 8d. Accordingly, after the leakage is detected, when the relief flow path switching valve 5 is operated again so that the excess fuel is not sent to the sub-line 6, the fuel level of the receiving tank 8a decreases to lower the float valve member 8b, and the fuel tank 1 and the canister 7 are returned to the communicating state through the vent valve 8 (
The jet pump 4 constituting the detecting device may have a structure shown in
In the embodiment shown in the drawings, the discharge nozzle 40 is integrally provided to an upper member 41a of the chamber 41 and projects downwardly from an inner wall of the upper member 41a. The discharge nozzle 40 is formed in a shape tapered toward a tail end 4a, and has an outer surface 40b as a tapered surface along an outer surface of a virtual cone and an inner diameter decreasing toward the tail end 40a.
The discharge port 42 is formed in an inner wall of a lower member 41b of the chamber 41. In the embodiment, an upper end of the discharge pipe 42a is integrally connected to the lower member 41b of the chamber 41 to form the discharge port 42. The discharge port 42 is provided to a bottom portion of a cone-shape concave portion 41c with a diameter gradually decreasing toward an opening edge of the discharge port 42. The tail end 40a of the discharge nozzle 40 is inserted into the concave portion 41c with a space between the outer surface of the discharge nozzle 40 and a wall surface of the concave portion 41c.
When the excess fuel is jetted out from the discharge nozzle 40, a negative pressure is effectively generated between the discharge nozzle 40 and the concave portion 41c. Accordingly, air is brought into the chamber 41 from the second air flow line 10 by the negative pressure, and air is sent to outside of the chamber 41 through the discharge port 42 together with the excess fuel.
As shown in
When a ratio of the inner diameter of the discharge nozzle 40 (inner diameter of the tail end 40a of the discharge nozzle 40) to the inner diameter of the discharge port 42 is in a range between approximately 1 to 3.5 and 1 to 5, the inner pressure of the fuel tank 1 is effectively increased in a short period of time.
In an experiment, the excess fuel was discharged from the discharge nozzle 40 at 100 l/h, the inner diameter of the discharge nozzle 40 was 1.3 mm, and the inner diameter of the discharge port 42 was varied in a range of 4.3 mm to 7 mm. While air was brought in through the second air flow line, the inner pressure of the fuel tank 1 was measured after 15 seconds and 30 seconds, respectively, after air was brought in. The results are shown in the following graph.
It was confirmed that the inner pressure of the fuel tank was effectively increased in a short period of time when the inner diameter of the discharge port 42 was in a range of 4.5 mm to 6.5 mm, i.e. the ratio of the inner diameter of the discharge nozzle 40 to the inner diameter of the discharge port 42 between approximately 1 to 3.5 and 1 to 5.
In another experiment, the excess fuel was discharged from the discharge nozzle 40 at 80 l/h, the inner diameter of the discharge nozzle 40 was 1.3 mm, and the inner diameter of the discharge port 42 was in a range of 4.3 mm to 7 mm. While air was brought in through the second air flow line, the inner pressure of the fuel tank 1 was measured after 15 seconds and 30 seconds, respectively, after air was brought in. The results are shown in the following graph.
In this experiment, it was also confirmed that the inner pressure on a side of the fuel tank was effectively increased in a short period of time when the inner diameter of the discharge port 42 was in a range of 4.5 mm to 6.5 mm, i.e. the ratio of the inner diameter of the discharge nozzle 40 to the inner diameter of the discharge port 42 between approximately 1 to 3.5 and 1 to 5.
According to the present embodiment, a method of detecting the leakage detects the fuel evaporation gas leakage on a side of the fuel tank 1 by using the leak detecting device described above.
The detecting method includes:
The relief flow path switching valve 5 is operated to supply the excess fuel to the receiving tank 8a of the vent valve 8, so that the float valve member 8b is floated to block the communicating portion 8c (
In this state, the inner pressure sensor 12 detects the inner pressure data on the side of the fuel tank 1 and the detected inner pressure is compared with the reference data, so that the unexpected gas leakage from the side of the fuel tank 1 can be precisely detected and determined. The detection and determination can be carried out by using a microcomputer and an electronic circuit. In a case that the unexpected leakage is detected, the leakage is notified to a driver.
The leakage detection is preferably carried out when an automobile starts idling. In other words, when the automobile becomes an idling state, the excess fuel is supplied to the receiving tank 8a of the vent valve 8 to forcibly send air in the fuel tank 1.
When the automobile is running, fuel in the fuel tank 1 swings and the inner pressure of the fuel tank 1 tends to be unstable. Due to vibrations, the float valve member 8b constituting the vent valve 8 also tends to be unstable in blocking the communicating portion 8c. Further, when the automobile is running, the internal combustion engine uses a larger quantity of fuel, thereby reducing the excess fuel to be sent to the jet pump 4. Accordingly, the leak detection is preferably limited only when the automobile is idling, thereby accurately detecting the leakage without the problems described above.
The disclosures of Japanese Patent Applications No. 2003-422488 filed on Dec. 19, 2003 and No. 2004-053643 have been incorporated in the application.
While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-422488 | Dec 2003 | JP | national |
| 2004-053643 | Feb 2004 | JP | national |
