JP2003020999A - Fuel system of lpg engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel system of an LPG engine capable of stabilizing the fuel injection from an injector by controlling of the air phase in the LPG fuel system. SOLUTION: (1) In the fuel system of the LPG engine, a pressurizing chamber 3 is formed separate from an LPG fuel tank 1, and a pump 2 is mounted between the LPG fuel tank the pressurizing chamber 3 for pressurizing the inside of the pressurizing chamber to the liquid phase. In addition, an open/close valve 4 is mounted on a passage 9 connecting the pressurizing chamber 3 and a delivery pipe 6. (2) Moreover, the fuel system of the LPG engine has an ECU 5 for controlling the opening/closing the open/close valve 4 so that the open/close valve 4 is open when the temperature of the delivery pipe 6 is at least a prescribed temperature.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel supply system (device) for an LPG (liquefied petroleum gas) engine.

[0002]

2. Description of the Related Art A fuel supply system for an engine utilizing LPG is known from Japanese Patent Laid-Open No. 10-252569. In the conventional LPG engine, the LPG fuel is LPG
It is guided from the tank to the delivery pipe and injected from each injector into the intake system of the engine. The LPG fuel is a liquid until it is injected from the injector, and is vaporized immediately after the injection.

[0003]

[Problems to be Solved by the Invention] However, the conventional LPG
In the fuel supply system of an engine, the temperature in the vicinity of the delivery pipe is raised by heat received from the engine, so that the LPG fuel may be partially vaporized by the delivery pipe or the like while flowing from the LPG tank to the injector (LPG fuel is approximately 4 MPa or less. And vaporizes at 97 ° C. or higher), and the jet is not stable when jetted from the injector in a gas-liquid mixed state. Also, L
If the engine is stopped in a state where the fuel supply system of the PG engine has a gas phase, the engine will not start easily when restarted, and the engine control will not be stable. The object of the present invention is to
An object of the present invention is to provide a fuel supply system for an LPG engine that can suppress the generation of a gas phase in the PG fuel supply system and stabilize the fuel injection from the injector.

[0004]

The above object can be achieved by the present invention described below. (1) A pressure chamber is provided separately from the LPG fuel tank, and a pump for pressurizing the pressure chamber to a liquid phase is provided between the LPG fuel tank and the pressure chamber, and a passage connecting the pressure chamber and the delivery pipe. Fuel supply system for LPG engine with on-off valve. (2) EC for controlling opening / closing of the opening / closing valve so that the opening / closing valve is opened when the temperature of the delivery pipe is equal to or higher than a predetermined temperature.
The fuel supply system of the LPG engine according to (1), in which U is provided.

In the fuel supply system of the LPG engine of the above (1), even if liquid LPG is partially vaporized and a gas phase (vaporized fuel) is generated in the fuel supply system, the gas is sent to the pressurizing chamber by the pump. At the same time, it is liquefied by pressurization and temporarily stored in the pressurizing chamber. Then, when the valve is opened, it is fed to the delivery pipe through the valve to lower the temperature of the delivery pipe, suppress the generation of a gas phase in the delivery pipe, and stabilize the fuel injection. In the fuel supply system of the LPG engine of the above (2), when the temperature of the delivery pipe becomes a predetermined temperature (for example, 90 ° C.) or higher, a gas phase (vaporized fuel) may be generated in the delivery pipe. Then, the on-off valve is opened by a command from the ECU, the liquid LPG from the pressurizing chamber is sent to the delivery pipe to lower the temperature of the delivery pipe, suppress the generation of a gas phase in the delivery pipe, and stabilize the fuel injection.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A fuel supply system for an LPG engine according to an embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, the LPG fuel tank 1 has a fuel passage 11
Is connected to a delivery pipe 6 (hereinafter, simply referred to as “delivery”), the LPG fuel is sent to the delivery 6 through the fuel passage 11 by the pump 10, and is injected from the delivery 6 to each intake manifold of the LPG engine through each injector 7. It The LPG fuel should be in a liquid state until it is injected from the injector 7, and is vaporized immediately after the injection.

A pressure chamber 3 is provided separately from the LPG fuel tank 1. The pressurizing chamber 3 is preferably provided in the vicinity of the delivery 6 in order to suppress vaporization of the LPG fuel between the pressurizing chamber 3 and the delivery 6. Further, it is desirable that the pressurizing chamber 3 is installed at a portion where the temperature is not raised as much as possible when the traveling wind is hit, and fins or the like are provided to increase the surface area and hit a large amount of air. The LPG fuel tank 1 and the pressurizing chamber 3 are connected by a passage 8, and the pressurizing chamber 3 and the delivery 6 or the vicinity thereof are connected by a passage 9.
The passage 8 has a pump 2 for pressurizing the pressurizing chamber 3 to a liquid phase.
An opening / closing valve 4 (for example, an ON-OFF electromagnetic valve) that opens / closes the passage 9 is provided in the passage 9.

The passage 8 is opened in the upper part of the LPG fuel tank 1 so that the gas phase in the LPG fuel tank 1 can be sucked out. The pressurizing pump 2 can pressurize the inside of the pressurizing chamber 3 to a predetermined pressure (for example, 4 MPa) or more, and stops the operation when the pressure in the pressurizing chamber 3 reaches a certain value (for example, 5 MPa) or more. The reason why the operation is stopped at a pressure equal to or higher than a certain value is that even if the pressure is further increased or the operation is continued, it is useless for changing the gas phase into the liquid phase. The operation of the pump 2 is controlled by the ECU 5 (engine control computer). As shown in FIG. 2, the control determines whether or not the pressure in the pressurizing chamber 3 is higher than a predetermined pressure (for example, 5 MPa) in step 101, and if not, proceeds to step 102 to operate the pump 2 The gas phase is sucked from the tank 1 and sent to the pressurizing chamber 3 and is liquefied. If it is higher than a predetermined pressure, the process proceeds to step 103 to stop the pump 2.

The operation of the on-off valve 4 is also controlled by the ECU 5. As shown in FIG. 3, the control of the on-off valve 4 determines in step 201 whether or not the temperature of the delivery 6 or its vicinity (detected by a temperature sensor (not shown)) is higher than a predetermined temperature (for example, 90 ° C.). If the temperature is higher than that, the routine proceeds to step 202, where the on-off valve 4 is opened and the liquid LPG fuel in the pressurizing chamber 3 is sent to the delivery 6. If it is not higher than the predetermined temperature, the routine proceeds to step 203 to close the on-off valve 4 and pressurize. The inside of the chamber 3 can be pressurized.

Next, the operation of the embodiment of the present invention will be described.
In the LPG fuel supply system, even if the liquid LPG fuel is partially vaporized and a gas phase is generated in the fuel supply system, the gas accumulates in the upper part of the LPG fuel tank 1 and is sucked by the pump 2 from there to be pressurized chamber. 3 is liquefied by pressurization by the pump 2 and stored in the pressurizing chamber 3. Then, when the temperature of the delivery 6 or the vicinity thereof rises due to heat received from the engine or the like, and a gas phase is about to be generated, the on-off valve 4 is opened, and when passing through the on-off valve 4, a partial expansion occurs and a very small amount of gas is generated. The liquid LPG that has turned into a low temperature is supplied to the delivery 6, the temperature of the delivery 6 is lowered, vaporization of the LPG fuel is suppressed, and fuel is injected from the injector 7 in a liquid state. As a result, stable fuel injection with no gas or almost no gas is possible, and the restartability is improved.

Further, the opening / closing valve 4 is opened / closed by the ECU 5, and is opened when the temperature of the delivery 6 exceeds a predetermined temperature (for example, about 90 ° C.), and is closed at other times. Therefore, the gas phase generation can be suppressed only when the gas phase is likely to occur, and the gas phase generation can be closed at other times to prepare for pressurization in the pressurizing chamber 3. The pump 2 also has a predetermined pressure (for example, 5 MPa).
Since the engine is stopped as described above, the driving energy is not constantly consumed to consume the driving energy, and the fuel efficiency is not lowered.

[0012]

According to the fuel supply system of the LPG engine of the first aspect, since the pressurizing chamber, the pump, and the on-off valve are provided, even if a gas phase occurs in the fuel supply system, the gas is sucked out by the pump to the pressurizing chamber. It can be liquefied and supplied to the delivery in a liquefied state when the on-off valve is opened, and the occurrence of a gas phase at the delivery can be suppressed and the fuel injection can be stabilized. According to the fuel supply system of the LPG engine of claim 2, since the on-off valve is opened when the temperature of the delivery reaches or exceeds the predetermined temperature, it is possible to effectively suppress the generation of the gas phase in the delivery. The fuel injection can be stabilized.

[Brief description of drawings]

FIG. 1 is a system diagram of a fuel supply system of an LPG engine according to an embodiment of the present invention.

FIG. 2 is an operation control flowchart of a pressurizing pump of the fuel supply system of the LPG engine according to the embodiment of the present invention.

FIG. 3 is an operation control flowchart of an opening / closing valve of a fuel supply system of the LPG engine according to the embodiment of the present invention.

[Explanation of symbols]

1 LPG fuel tank 2 (pressurizing) pump 3 Pressurization chamber 4 on-off valve 5 ECU (engine control computer) 6 Delivery pipe 7 injectors 8, 9 passages 10 pumps 11 Fuel passage

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 360 F02D 45/00 360A (72) Inventor Kazuya Nakata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto Car Co., Ltd. (72) Inventor Jun Yamada 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (72) Inventor Toru Sato 1-Ai, 1-chome, Kyowa-cho, Obu-shi, Aichi Kogyo Co., Ltd. F-term (reference) 3G084 AA05 BA11 DA12 FA00 3G092 AA08 AB07 DE05S DE09S DE11S FA23 3G301 HA22 JA03 LB06 ND01 PB08Z

Claims (2)

[Claims] 1. A pressurizing chamber is provided separately from the LPG fuel tank, a pump for pressurizing the pressurizing chamber to a liquid phase is provided between the LPG fuel tank and the pressurizing chamber, and the pressurizing chamber and the delivery pipe are connected. A fuel supply system for an LPG engine that has an on-off valve in the passage. 2. The fuel supply system for an LPG engine according to claim 1, further comprising an ECU for controlling opening / closing of the opening / closing valve so that the opening / closing valve is opened when the temperature of the delivery pipe is equal to or higher than a predetermined temperature.