JP6327201B2 - Evaporative fuel processing equipment - Google Patents

Description

  The present invention relates to a fuel vapor processing apparatus.

  2. Description of the Related Art Conventionally, an evaporative fuel processing apparatus for processing evaporative fuel generated in a fuel tank of an internal combustion engine without releasing it into the atmosphere is known (for example, see Patent Document 1).

  Such an evaporative fuel processing apparatus temporarily collects (evaporates and holds) evaporative fuel generated in the fuel tank in the canister, and uses the negative pressure of the intake system of the internal combustion engine to convert the evaporative fuel in the canister to the internal combustion engine. Is introduced (purged) into the intake system.

  Specifically, the evaporative fuel processing apparatus includes a fuel tank for storing fuel, a canister for recovering evaporative fuel generated in the fuel tank, a vapor pipe connecting the fuel tank and the canister, a canister and an internal combustion engine A purge pipe for connecting to the intake system of the engine and an atmospheric pipe for communicating the canister to the atmosphere side are provided. The vapor pipe is provided with a block valve for shutting off the fuel tank and the canister, and the purge pipe is provided with a purge control valve for controlling the amount of fuel vapor introduced into the intake system. .

JP 2005-105998 A

  Here, some conventional evaporative fuel processing apparatuses as described above include a relief valve for releasing the internal pressure of the fuel tank when an abnormality occurs. This relief valve is provided, for example, on a cap that is detachably attached to a fuel filler port of the fuel tank. However, this relief valve is subjected to the tank internal pressure when the block valve is closed to maintain the fuel tank in a sealed state, but it is necessary to prevent the relief valve from being opened due to the tank internal pressure during normal operation. . For this reason, for example, the relief valve is configured to close within a pressure range in which the strength (pressure resistance strength) of the fuel tank is guaranteed, and to open outside the pressure range. Therefore, when an abnormality occurs, the tank internal pressure becomes excessive, and there is a possibility that problems such as deformation of the fuel tank may occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an evaporative fuel processing apparatus capable of suppressing an excessive tank internal pressure when an abnormality occurs. is there.

  An evaporated fuel processing apparatus according to the present invention includes a fuel tank for storing fuel, a canister for recovering evaporated fuel generated in the fuel tank, a vapor passage connecting the fuel tank and the canister, a canister and an internal combustion engine A purge passage connecting the intake system, an atmospheric passage for communicating the canister to the atmosphere side, a cap detachably attached to the fuel filler of the fuel tank, and a first relief valve provided on the cap . The fuel vapor processing apparatus includes a second relief valve provided in the purge passage or the canister. The second relief valve is configured to open when the pressure in the purge passage is outside a predetermined range, and the predetermined range is within a pressure range in which strength is guaranteed in the fuel tank.

  With this structure, when the pressure in the purge passage is out of the predetermined range when an abnormality such as the atmospheric passage is blocked, the second relief valve is opened, so that the internal pressure in the purge passage and the tank internal pressure are excessive. Can be suppressed. Therefore, deformation and damage of the fuel tank can be suppressed.

  According to the fuel vapor processing apparatus of the present invention, it is possible to suppress the tank internal pressure from becoming excessive when an abnormality occurs.

It is a schematic block diagram for demonstrating the evaporative fuel processing apparatus by 1st Embodiment of this invention. It is sectional drawing which showed the 2nd relief valve of the evaporated fuel processing apparatus of FIG. It is a schematic block diagram for demonstrating the evaporative fuel processing apparatus by 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, with reference to FIG. 1 and FIG. 2, the evaporative fuel processing apparatus 100 by 1st Embodiment of this invention is demonstrated.

  The evaporated fuel processing apparatus 100 is configured to process the evaporated fuel generated in the fuel tank 1 of the internal combustion engine without releasing it into the atmosphere. As shown in FIG. 1, the fuel vapor processing apparatus 100 includes a fuel tank 1, a canister 2, a vapor pipe 3, a purge pipe 4, an atmospheric pipe 5, a block valve unit 6, a purge control valve 7, It has. The vapor pipe 3, the purge pipe 4, and the atmospheric pipe 5 are examples of the “vapor passage”, “purge passage”, and “atmospheric passage” of the present invention, respectively.

  The fuel tank 1 is configured to store the fuel F of the internal combustion engine. A fuel pump 11 is provided inside the fuel tank 1, and the fuel pump 11 and an injector (not shown) of the internal combustion engine are connected by a fuel supply pipe 12. Thereby, when the fuel pump 11 is driven, the fuel F in the fuel tank 1 is supplied to the injector via the fuel supply pipe 12.

  The fuel tank 1 is provided with a liquid level sensor 13 for detecting the liquid level of the fuel F stored therein, and a tank for detecting the pressure (tank internal pressure) of the upper space S on the liquid level. An internal pressure sensor 14 is provided. The detection results of the liquid level sensor 13 and the tank internal pressure sensor 14 are input to an ECU (not shown).

  The fuel tank 1 is connected to an inlet pipe 8 for refueling. The inlet pipe 8 has an oil supply port 8a formed at the upper end, and a cap 81 is detachably attached to the oil supply port 8a. A check valve 82 is provided near the lower end of the inlet pipe 8. Further, the vicinity of the fuel inlet 8 a of the inlet pipe 8 and the upper space S of the fuel tank 1 are connected by a circulation pipe 83.

  The canister 2 contains an adsorbent such as activated carbon therein, and is configured to collect (adsorb and hold) the evaporated fuel generated in the fuel tank 1. A vapor pipe 3, a purge pipe 4 and an atmospheric pipe 5 are connected to the canister 2.

  The vapor pipe 3 connects the fuel tank 1 and the canister 2 and is provided to introduce the evaporated fuel generated in the fuel tank 1 into the canister 2. An ROV (Roll Over Valve) 31 is provided at the upstream end of the vapor pipe 3. For this reason, it is possible to prevent the liquid phase fuel from entering the vapor pipe 3.

  Further, the vapor pipe 3 is provided with a blocking valve unit 6. The block valve unit 6 includes a block valve and a bidirectional check valve provided in parallel with the block valve.

  The block valve is an electromagnetic valve that is opened and closed by the ECU, and is configured to close when not energized and open when energized. For this reason, when the blocking valve is opened, the fuel tank 1 and the canister 2 are communicated, and when the blocking valve is closed, the fuel tank 1 and the canister 2 are shut off.

  The bidirectional check valve has a forward relief valve and a backward relief valve. The forward-direction relief valve is configured to open when the pressure in the fuel tank 1 is significantly higher than the pressure in the canister 2. On the other hand, the reverse relief valve is configured to open when the pressure in the fuel tank 1 is significantly lower than the pressure in the canister 2.

  The purge pipe 4 connects the canister 2 and an intake system (not shown) of the internal combustion engine, and is provided for introducing the evaporated fuel collected in the canister 2 into the intake system. The purge pipe 4 is provided with a purge control valve 7 which is a VSV (Vacuum Switching Valve) whose opening degree can be adjusted. The purge control valve 7 is a normally closed valve controlled by the ECU, and is configured to open when a predetermined purge condition is satisfied.

  The atmospheric pipe 5 has one end connected to the canister 2 and the other end open to the atmosphere in the vicinity of the fuel filler opening 8a. That is, the atmospheric pipe 5 is provided to communicate the canister 2 to the atmospheric side. An air filter 51 is provided at the other end of the atmospheric pipe 5.

  In the evaporated fuel processing apparatus 100, when the block valve of the block valve unit 6 is opened, the evaporated fuel in the fuel tank 1 is introduced into the canister 2 and collected. It should be noted that gaseous components other than the evaporated fuel are discharged from the atmospheric pipe 5 into the atmosphere.

  Thereafter, when the purge control valve 7 is opened while the evaporated fuel is adsorbed and held in the canister 2 and the blocking valve is closed, the negative pressure of the intake system of the internal combustion engine acts on the canister 2. Thus, the atmosphere is introduced into the canister 2 from the atmosphere pipe 5, and the evaporated fuel in the canister 2 is introduced into the intake system through the purge pipe 4 together with the atmosphere. As a result, the evaporated fuel generated in the fuel tank 1 is burned in the internal combustion engine, so that the evaporated fuel can be processed without being released into the atmosphere.

  Here, the evaporated fuel processing apparatus 100 includes a first relief valve 81a and a second relief valve 9 for fail safe. The first relief valve 81 a and the second relief valve 9 are configured to open and release the internal pressure when an abnormality occurs in the evaporated fuel processing apparatus 100.

  The 1st relief valve 81a is provided in the cap 81 with which the oil supply opening | mouth 8a is mounted | worn. For example, the first relief valve 81a is closed within a pressure range in which the strength (pressure strength) of the fuel tank 1 is guaranteed (hereinafter referred to as “pressure strength guarantee range”), and is outside the pressure strength guarantee range. The valve is configured to open. This is because the internal pressure of the tank when the sealing valve of the blocking valve unit 6 is closed and the fuel tank 1 is maintained in a sealed state acts on the first relief valve 81a.

  The second relief valve 9 is provided in the purge pipe 4 and is disposed between the canister 2 and the purge control valve 7. The second relief valve 9 is closed when the pressure in the purge pipe 4 is within a predetermined range (for example, a range between −5 kPa and +5 kPa), and the pressure in the purge pipe 4 is outside the predetermined range. It is configured to open sometimes. The predetermined range in which the second relief valve 9 is closed is within the pressure strength guarantee range of the fuel tank 1 described above. For this reason, the pressure range in which the second relief valve 9 is closed is narrower than the pressure range in which the first relief valve 81a is closed. That is, the second relief valve 9 is opened to release the internal pressure before the pressure in the purge pipe 4 falls outside the pressure strength guarantee range. The reason why such a valve opening characteristic of the second relief valve 9 can be set is that the pressure is less generated in the purge pipe 4 than in the fuel tank 1. That is, since the internal pressure of the purge pipe 4 at the normal time is within a predetermined range narrower than the pressure resistant strength guarantee range, the second relief valve 9 opens when the internal pressure is outside the predetermined range and is in an abnormal state. It is designed to release the internal pressure.

  Further, the second relief valve 9 includes a positive pressure relief valve 91 and a negative pressure relief valve 92 as shown in FIG.

  The positive pressure relief valve 91 is configured to open when the internal pressure of the purge pipe 4 exceeds an upper limit value (for example, 5 kPa) within a predetermined range. The positive pressure relief valve 91 includes a check ball 91a that opens and closes an opening formed in the purge pipe 4, a compression coil spring 91b that biases the check ball 91a in the valve closing direction, and a holding plate that holds the compression coil spring 91b. 91c. The compression coil spring 91b and the holding plate 91c are disposed on the outside (atmosphere side) of the purge pipe 4.

  The negative pressure relief valve 92 is configured to open when the internal pressure of the purge pipe 4 falls below a lower limit value (for example, −5 kPa) of a predetermined range. The negative pressure relief valve 92 includes a check ball 92a that opens and closes an opening formed in the purge pipe 4, a compression coil spring 92b that urges the check ball 92a in the valve closing direction, and a holding member that holds the compression coil spring 92b. 92c. The compression coil spring 92 b and the holding member 92 c are disposed in the purge pipe 4.

-Effect-
In the first embodiment, as described above, the second relief valve 9 is provided in the purge pipe 4, and the second relief valve 9 is configured to open when it is outside a predetermined range narrower than the pressure-resistant strength guarantee range. doing. With this configuration, when the internal pressure of the purge pipe 4 falls outside a predetermined range when an abnormality occurs such as when the atmospheric pipe 5 is blocked by foreign matter (for example, water, ice, mud, insects) or the like, the second relief valve When 9 opens, it can suppress that the internal pressure of the purge piping 4 and the tank internal pressure become excessive. Therefore, the tank internal pressure can be released before the internal pressure of the fuel tank 1 falls outside the pressure strength guarantee range, so that the fuel tank 1 can be prevented from being deformed or damaged. Even when the first relief valve 81a is closed, the internal pressure can be released by the second relief valve 9.

(Second Embodiment)
Next, with reference to FIG. 3, the evaporative fuel processing apparatus 200 by 2nd Embodiment of this invention is demonstrated. In the second embodiment, unlike the first embodiment, the second relief valve 9 (see FIG. 1) is not provided.

  In the evaporated fuel processing apparatus 200 according to the second embodiment, when a predetermined negative pressure is generated in the fuel tank 1 due to the atmospheric pipe 5 being closed, the purge control valve 7 is set when the internal combustion engine is stopped. The valve is configured to open. Thereby, even if the atmospheric piping 5 is closed, the predetermined negative pressure in the fuel tank 1 can be extracted to the intake system side of the internal combustion engine. The tank internal pressure can be determined based on the detection result of the tank internal pressure sensor 14.

  Thereafter, when the internal combustion engine is restarted, the purge control valve 7 is closed to return to the normal control. In addition, even if a positive pressure is generated in the fuel tank 1 by closing the atmospheric piping 5, the positive pressure can be extracted to the intake system side of the internal combustion engine when the internal combustion engine is operated.

(Other embodiments)
In addition, embodiment disclosed this time is an illustration in all the points, Comprising: It does not become a basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, the technical scope of the present invention includes all modifications within the meaning and scope equivalent to the scope of the claims.

  For example, in the first embodiment, the example in which the second relief valve 9 is provided in the purge pipe 4 is shown, but the present invention is not limited thereto, and the second relief valve may be provided in the canister.

  In the first embodiment, the second relief valve 9 has the positive pressure relief valve 91 and the negative pressure relief valve 92. However, the present invention is not limited thereto, and the second relief valve has only the negative pressure relief valve. You may do it.

  In the first embodiment, the second relief valve 9 is a check valve. However, the present invention is not limited to this, and the second relief valve may be a crushable diaphragm valve.

  In the first embodiment, the example in which the first relief valve 81a opens outside the pressure resistance guarantee range is shown. However, the pressure range in which the second relief valve is closed is not limited to this. If the pressure range is narrower than the pressure range in which the relief valve is closed, the first relief valve may be opened within the pressure strength guarantee range.

  In the second embodiment, the purge control valve 7 is closed when the internal combustion engine is restarted. However, the present invention is not limited to this, and the purge is performed after a predetermined time has elapsed since the internal combustion engine was stopped. The control valve may be closed. Further, it may be determined whether or not the negative pressure is released, and the purge control valve may be closed when the negative pressure is released.

  INDUSTRIAL APPLICABILITY The present invention can be used in an evaporated fuel processing apparatus for processing evaporated fuel generated in a fuel tank of an internal combustion engine without releasing it into the atmosphere.

1 Fuel tank 2 Canister 3 Vapor piping (vapor passage)
4 Purge piping (Purge passage)
5 Atmospheric piping (atmospheric passage)
8a Refueling port 9 Second relief valve 81 Cap 81a First relief valve 100 Evaporated fuel processing device

Claims (1)

A fuel tank for storing fuel;
A canister for recovering evaporated fuel generated in the fuel tank;
A vapor passage connecting the fuel tank and the canister;
A purge passage connecting the canister and the intake system of the internal combustion engine;
An atmospheric passage for communicating the canister to the atmosphere side;
A cap detachably attached to a fuel filler port of the fuel tank;
An evaporative fuel processing apparatus comprising a first relief valve provided on the cap,
A second relief valve provided in the purge passage or the canister;
The second relief valve is configured to open when the pressure in the purge passage is outside a predetermined range,
The evaporative fuel processing apparatus according to claim 1, wherein the predetermined range is within a pressure range in which strength is guaranteed in the fuel tank.

Images