JP2003254104A - Liquefied gas fuel supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquefied gas fuel supply device for improving the filling performance of fuel by reducing a raised internal pressure of a fuel tank. <P>SOLUTION: The fuel tank 2 is provided with a sub-fuel tank 15 communicated therewith through a communication pipe 17, and a manual valve 18 (communication valve) is mounted for opening and closing the communication pipe 17. When the internal pressure of the fuel tank 2 is higher than the predetermined pressure the manual valve 18 is opened when the internal pressure of the fuel tank 2 is reduced lower than the filling pressure, the valve 18 is closed to charge the fuel. As the valve 18 is opened or closed again after filling, the pressure in the fuel tank 2 can be reduced, and the filling performance of the fuel can be improved with a simple structure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquefied gas fuel supply system for an internal combustion engine, and more particularly to a liquefied gas fuel supply system capable of improving the fuel filling property of a fuel tank.

[0002]

2. Description of the Related Art A liquefied gas fuel supply apparatus for pressurizing a liquefied gas fuel such as LPG stored in a fuel tanker to send it to a delivery pipe and inject it by an injector provided in the delivery pipe to supply it to an engine. It is known in Japanese Patent Publication No. 6-502473. According to the above publication, fuel having a variable vapor pressure stored in a tank and having a variable vapor pressure depending on the ambient temperature in the tank is fueled at an absolute pressure which is maintained at a constant differential pressure higher than the variable vapor pressure in the tank. Is sent to a fuel inflow side rail (delivery pipe) and an injector, the absolute pressure of fuel is monitored, and the fuel injection pulse width is changed according to the absolute pressure of fuel along with other normal engine parameters.

[0003]

However, in the configuration disclosed in the above publication, the surplus fuel passing through the pressure regulator provided downstream of the delivery pipe is returned to the fuel tank through the return pipe, and the fuel is again fed. It is pumped to the delivery pipe by a pump and circulates. At this time, the fuel circulates while absorbing the heat of the engine, so that the fuel temperature in the fuel tank gradually rises and the pressure in the fuel tank rises. Therefore, when attempting to fill the fuel, the filling speed may be lowered to deteriorate the filling property, and filling may be impossible depending on the filling pressure. Therefore, it is an object of the present invention to provide a liquefied gas fuel supply device capable of reducing the increased internal pressure of the fuel tank to improve the fuel filling property.

[0004]

In order to solve the above-mentioned problems, the invention of claim 1 is provided in the delivery pipe by pressurizing the liquefied gas fuel in the fuel tank by a fuel pump and sending it to the delivery pipe. After supplying fuel to the engine with the injector, and adjusting the pressure in the fuel pipe with the pressure regulator,
In a liquefied gas fuel supply device configured to return surplus fuel to the fuel tank, a sub-fuel tank connected to the fuel tank by a communication pipe is provided, and a communication valve for opening and closing the communication pipe is provided, and When the internal pressure of the fuel tank is higher than a predetermined pressure, the communication valve is opened, and when the internal pressure of the fuel tank becomes lower than the filling pressure, the communication valve is closed and the fuel is filled. It is characterized in that the communication valve is opened and closed. Further, the invention of claim 2 is characterized in that the communication valve is constituted by a manual valve or a solenoid valve. Further, according to the invention of claim 3, the operation lamp is turned on when the pressure in the fuel tank is higher than a predetermined pressure set to a value lower than the filling pressure, and is turned off when the pressure is low. Is characterized by.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a liquefied gas fuel supply device according to an embodiment of the present invention. In FIG. 1, a fuel tank 2 containing a liquefied gas fuel 1 has a filling unit 3 for injecting fuel, a level cage 4 for displaying the amount of fuel, and a fuel pressure for detecting the fuel pressure in the fuel tank 2. A tank fuel pressure sensor 5, a fuel pump 7 for pressurizing and sending fuel to the delivery pipe 6, and a pressure regulator 8 for adjusting the fuel pressure in the delivery pipe 6 are mounted. The tank fuel pressure sensor 5 is an E for electrically controlling the engine 10.
It is connected to the CU (11).

A sub-tank 15 is provided in the fuel tank 2, and the fuel tank 2 and the sub-tank 15 are connected by a communication pipe 17 (in the present embodiment, they are communicated with the bottom portion). A manual valve 18 shown as an example of a communication valve is provided in the middle of the communication pipe 17, and is configured to open and close the communication pipe 17. A fuel supply pipe 12 is connected to the end of the fuel pump 7 and communicates with a delivery pipe 6 fixed to the intake manifold 13. A tank shutoff valve 14 is provided near the outlet of the fuel tank 2 in the middle of the fuel supply pipe 12, and is opened / closed by an electric signal from the ECU (11). In order to effectively grasp the operation timing of the manual valve 18, the operation lamp 9 is connected from the ECU (11),
It is turned on / off by an electric signal from the CU (11).
The operation lamp 9 is provided at a location easy to see when the fuel is filled in the fuel tank 2.

A plurality of injectors 16 are sandwiched between the delivery pipe 6 and the intake manifold 13,
Delivery pipe 6 by an electric signal from the ECU (11)
The internal fuel is injected into the engine 10. A return pipe 19 is connected to the outlet of the delivery pipe 6 and communicates with the upper portion of the fuel tantalum 2. A pressure regulator 8 is provided at the end of the return pipe 19 in the fuel tank 2 and is configured to adjust the fuel pressure in the delivery pipe 6. Excess fuel due to the adjustment is configured to flow directly from the pressure regulator 8 into the fuel tank 2. The fuel supply pipe 1
2, the delivery pipe 6 and the return pipe 19 constitute a fuel pipe. Further, the pressure regulator 8 may be provided near the outlet of the delivery pipe 6.

Next, the operation of this embodiment will be described with reference to FIGS. FIG. 2 is a flow chart of the fuel filling operation of the fuel tank of this embodiment. In FIG. 1, when an ignition switch (not shown) is turned on, the tank shutoff valve 14 is opened and the fuel pump 7 is operated to pressurize the liquefied gas fuel 1 by a predetermined pressure and send it to the delivery pipe 6. The fuel that has passed through the delivery pipe 6 reaches the pressure regulator 8, and after the pressure is adjusted, the surplus fuel is discharged from the pressure regulator 8 and flows into the fuel tank 2.

In this way, the pressure in the delivery pipe 6 is kept higher than the pressure in the fuel tank 2 by a predetermined pressure. The injector 16 is actuated by an electric signal from the ECU (11) to transfer the fuel in the delivery pipe 6 to the engine 1
The intake manifold 13 of 0 is injected to operate the engine 10. While the fuel pump 7 is operating, the tank pressure is sampled by the tank fuel pressure sensor 5 at predetermined time intervals and processed by the CPU (11).

The fuel discharged from the pressure regulator 8 is pumped again to the delivery pipe 6 by the fuel pump 7 and circulates. During the circulation, the temperature of the fuel rises due to the exhaust heat of the engine 10, and the temperature of the fuel in the fuel tantalum 2 rises, so that the fuel evaporates and the pressure in the fuel tank rises. For example, when the operation is continued at the outside air temperature of 20 ° C and the fuel tank temperature of 20 ° C as described above, the return fuel causes the temperature of the fuel tank to reach 40 ° C and the fuel temperature of the filling stand (20 ° C). ), The fuel tank internal pressure is higher than the filling pressure (Pr), and the filling property is reduced. Even when the fuel in the fuel tank 2 is used up, about 15% of the vaporized fuel, so-called dead gas, which cannot be pumped by the fuel pump 7, remains in the fuel tank 2 and a high tank pressure is maintained, so filling is performed. Sex decreases.

The operation at the time of filling will be described with reference to FIG. In FIG. 2, in step (hereinafter simply referred to as S) 100, the internal pressure of the fuel tank 2 is sampled by the tank fuel pressure sensor 5, and the internal pressure of the fuel tank is set to a predetermined value lower than the filling pressure (Pr). When it is lower than (Pt), that is, when it is determined to be No, the operation lamp 9 does not light up, so that fuel is filled in S108 and the operation ends. If the pressure in the fuel tank is higher than the predetermined pressure (Pt) in S100, that is, if it is determined to be Yes, S10
In 1, the operation lamp 9 is turned on by an electric signal from the ECU to prompt the opening of the manual valve 18. Then, in S102, the filler opens the manual valve 18. Since the liquefied gas fuel 1 flows into the sub-fuel tank 15 by opening the manual valve 18, the pressure inside the fuel tank 2 is reduced and the vaporization of the liquefied gas fuel 1 is promoted. The reduced pressure is further accelerated.

At S103, when the internal pressure of the fuel tank 2 becomes lower than the filling pressure (Pr), the manual valve operating lamp 9 is turned off (S104), so that the filler closes the manual valve 18 at S105. Then, in S106, the fuel is filled. At this time, since the pressure in the fuel tank 2 is lower than the filling pressure (Pr), the filling can be easily performed. Since the pressure in the sub-fuel tank 15 is higher than the pressure in the fuel tank 2 when the filling is completed, the manual valve 18 is opened and closed again in S107 to make the pressures in both tanks 2 and 15 uniform. To In addition,
A known electromagnetic valve is provided in place of the manual valve 18, and the operation lamp 9
The communication pipe 17 may be opened and closed according to the signal of. As a result, the same action and effect as described above are produced.

[0013]

Since the present invention is configured as described above, it has the following effects. That is, according to the first and second aspects of the invention, the fuel tank is provided with the sub-fuel tank that is communicated with the communication pipe, the communication valve for opening and closing the communication pipe is provided, and the internal pressure of the fuel tank is higher than the predetermined pressure. If it is higher, the communication valve is opened, and when the pressure in the fuel tank becomes lower than the filling pressure, the communication valve is closed to fill the fuel, and after the filling, the communication valve is opened and closed again. Thus, the pressure in the fuel tank can be reduced to improve the fuel filling property. Further, in the invention of claim 3, the operation lamp is turned on when the pressure in the fuel tank is higher than a predetermined pressure, and turned off when the pressure is lower than the predetermined pressure. Therefore, the operation timing of the communication valve is visually effective. Since it can be grasped in advance, the filler does not make a mistake in the operation.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a liquefied gas fuel supply device according to an embodiment of the present invention.

FIG. 2 is an operation flowchart at the time of filling fuel into a fuel tank of the liquefied gas fuel supply device according to an embodiment of the present invention.

[Explanation of symbols]

1 Liquefied gas fuel 2 fuel tank 6 Delivery pipe 7 Fuel pump 8 Pressure regulator 10 engine 15 Sub fuel tank 16 injectors 17 Communication pipe 18 Manual valve (communication valve) 19 Return pipe

Continued front page    (72) Inventor Fusaharu Omura             1 Ai 1-1-1, Kyowa-cho, Obu City, Aichi Prefecture             Sankogyo Co., Ltd. (72) Inventor Toru Sato             1 Ai 1-1-1, Kyowa-cho, Obu City, Aichi Prefecture             Sankogyo Co., Ltd. (72) Inventor Masaharu Wakabayashi             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Toshihiro Kawai             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Mitsunobu Uchida             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute F term (reference) 3G092 AA01 AA06 AB07 AB08 CB07                       DE09S DE12S DF08 DF09

Claims (3)

[Claims] 1. A liquefied gas fuel in a fuel tank is pressurized by a fuel pump and sent to a delivery pipe, fuel is supplied to an engine by an injector provided in the delivery pipe, and pressure in the fuel pipe is adjusted by a pressure regulator. In a liquefied gas fuel supply device configured to return excess fuel to the fuel tank after pressure adjustment, a sub-fuel tank connected to the fuel tank by a communication pipe is provided, and a communication valve for opening and closing the communication pipe. In addition, when the internal pressure of the fuel tank is higher than a predetermined pressure, the communication valve is opened, and when the internal pressure of the fuel tank becomes lower than the filling pressure, the communication valve is closed to fill the fuel. The liquefied gas fuel supply device is characterized in that the communication valve is opened and closed again after filling. 2. The liquefied gas fuel injection device according to claim 1, wherein the communication valve is a manual valve or a solenoid valve. 3. The operation lamp is turned on when the pressure in the fuel tank is higher than a predetermined pressure set to a value lower than the filling pressure, and turned off when the pressure is low. The liquefied gas fuel supply device according to claim 1 or 2.