JP2002295312A - Fuel supply device for gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable instantaneous running after an engine is started. SOLUTION: This fuel supply device for a gas engine is constituted by including a cylinder 10 storing compressed natural gas(CNG), a regulator 16 pressure governing the CNG to a prescribed pressure, a high pressure pipe 14 guiding the CNG stored in the cylinder 10 to the regulator 16, a main stop valve 12 opening/closing the high pressure pipe 14 to be associated with the gas engine, a bypass pipe 36 provided so as to bypass the mainn stop valve 12 to connect its upstream/downstream, and a manually operated opening/closing valve 38 manually opening/closing the bypass pipe 36. In this way thus constituted, prior to starting of the engine, the manually operated opening/closing valve 38 is operated to open, when the bypass pipe 36 is opened, gas fuel in the upstream of the main stop valve 12 flows in the downstream, and a fuel pressure difference thereof is reduced in a short time. Under this condition, when the CNG engine is started, the main stop valve 12 is fully opened simultaneously with starting the engine, and instantaneous running can be started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for a gas engine, and more particularly to a technique for improving running performance immediately after starting the engine.

[0002]

2. Description of the Related Art Recently, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-264821, compressed natural gas (Compressed Natural Gas) has been disclosed.
al Gas (hereinafter referred to as “CNG”) has been developed as a fuel. As shown in FIG. 2, a fuel supply device for a CNG engine includes a cylinder 1 as a fuel container.
, Main stop valve 2, regulator 3, fuel filter 4
And a low-pressure fuel cutoff valve 5 and a fuel injection valve 6. CNG stored in the cylinder 1 is supplied to the regulator 3 through a high-pressure pipe 7 in which the main stop valve 2 is interposed.
After being reduced to a predetermined pressure, the fuel is guided to a fuel injection valve 6 through a low-pressure pipe 8 in which a fuel filter 4 and a low-pressure fuel cutoff valve 5 are provided.

When the CNG engine is stopped, the main stop valve 2 automatically closes the high-pressure pipe 7 and shuts off fuel supply to the downstream side. That is, as shown in FIG. 3, when the coil 2A is not energized (the engine is in a stopped state), the plunger 2B is pressed by the spring 2C, the pilot valve 2D and the main valve 2E are seated, and furthermore, the valve back surface. The more upstream fuel pressure acts,
Each valve is crimped to a valve seat. On the other hand, immediately after the coil 2A is energized to start the engine, the plunger 2B integrated with the pilot valve 2D having a small opening area is pulled up by the play of the pin 2F due to the magnetic force, and the fuel flows out downstream. At this time, the main valve 2 having a large opening area
E does not open because the pressing force by the fuel pressure from the upstream side is large. When the fuel pressure on the downstream side increases due to the fuel flowing out of the pilot valve 2D and the fuel pressure difference between the upstream side and the downstream side decreases, the main valve 2E is pulled up by magnetic force and opens.

[0004]

However, since the main valve 2E of the main stop valve 2 does not open when the fuel pressure difference between the upstream side and the downstream side is large, the following problems may occur. there were. That is, the regulator 3
In this case, since the surrounding heat is taken away by the adiabatic expansion of CNG, the engine cooling water is circulated from the viewpoint of preventing overcooling. Then, when the engine is stopped, the CN around the regulator 3 is reduced as the temperature of the engine coolant decreases.
The temperature of G also decreases, and the fuel pressure downstream of the main stop valve 2 gradually decreases. If the time from the stop of the engine to the start of the engine is long, the fuel pressure difference between the upstream side and the downstream side of the main stop valve 2 becomes large. Therefore, immediately after the engine is started, the pilot valve 2D of the main stop valve 2 opens but the main valve 2E
Did not open, and the output for traveling could not be obtained due to insufficient fuel supply.

In view of the above problems, the present invention reduces the fuel pressure difference between the upstream side and the downstream side of the main stop valve in a short time so that the vehicle can run immediately after the engine is started. Accordingly, an object of the present invention is to provide a fuel supply device for a gas engine with improved running performance.

[0006]

According to the present invention, a fuel container for storing a gaseous fuel, a regulator for regulating the gaseous fuel to a predetermined pressure, and a gaseous fuel stored in the fuel container are provided. A fuel passage leading to the regulator,
A main stop valve that opens and closes the fuel passage in conjunction with the gas engine, a bypass passage that connects the upstream side and the downstream side so as to bypass the main stop valve, and a manual that manually opens and closes the bypass passage An on-off valve, and a fuel supply device for the gas engine.

According to such a configuration, to start the gas engine in a state where the fuel pressure difference between the upstream side and the downstream side of the main stop valve is large, the following may be performed. That is, prior to starting the engine, the manual open / close valve is opened to open the bypass passage. Then, the upstream side and the downstream side of the main stop valve communicate with each other, and the gaseous fuel on the upstream side flows into the downstream side due to the fuel pressure difference, and the fuel pressure difference decreases in a short time. Then, after closing the bypass passage by closing the manual on-off valve, the gas engine is started by operating, for example, an ignition switch to a starting position. At this time, since the fuel pressure difference between the upstream side and the downstream side of the main stop valve is small, the main stop valve is fully opened at the same time when the engine is started, and sufficient fuel is supplied to the gas engine. Becomes possible.

[0008] The invention according to claim 2 is characterized in that the manual on-off valve can be remotely operated from a driver's seat.
According to such a configuration, the driver can open and close the bypass passage while sitting in the driver's seat, and the labor required for starting the engine is reduced. According to the third aspect of the present invention, the pressure difference detecting means for detecting the fuel pressure difference between the upstream side and the downstream side of the main stop valve, and the fuel pressure difference detected by the pressure difference detecting means is less than a predetermined value. And a notifying means for notifying at that time.

With this configuration, when the fuel pressure difference between the upstream side and the downstream side of the main stop valve becomes equal to or less than a predetermined value, the driver is notified that the difference is less than a predetermined value. It becomes possible to recognize that it has been established. In addition, the manual on-off valve can be opened only for the minimum necessary time, and the time until the start of traveling can be minimized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. FIG. 1 shows the CNG engine
1 shows a configuration to which a fuel supply device for a gas engine according to the present invention (hereinafter, referred to as “fuel supply device”) is applied. CNG stored in a cylinder 10 as a fuel container is guided to a regulator 16 via a high-pressure pipe 14 (fuel passage) in which a main stop valve 12 is interposed. C led to regulator 16
The NG is regulated to a predetermined pressure while being prevented from being supercooled by the engine cooling water, and is guided to the fuel injection valve 24 through the low pressure pipe 22 in which the fuel filter 18 and the low pressure fuel cutoff valve 20 are interposed. CNG led to the fuel injection valve 24 is:
The fuel is injected and supplied into an intake passage (not shown) according to the engine operating state.

The main stop valve 12 and the low pressure fuel cutoff valve 20 are C
When the NG engine stops, each of the high-pressure pipes 14
And the low-pressure pipe 22 is automatically closed, and the fuel supply to the downstream side is shut off. The main stop valve 12
Is required by law, but some vehicles do not have the low-pressure fuel cutoff valve 20. In the main stop valve 12, as described above, when starting the CNG engine, first, the pilot valve having a small opening area is opened,
The upstream CNG is allowed to flow downstream. And CNG
The fuel pressure on the downstream side of the main stop valve 12 increases due to the outflow of
The main valve is opened only when the fuel pressure difference between the upstream side and the downstream side becomes small.

The high pressure pipe 14 on the upstream side of the main stop valve 12 includes:
In order to fill the consumed CNG, a fuel filling pipe 28 provided with a check valve 26 is connected. Fuel filling pipe 2
A fuel filling port 30 is fixed to the tip of the fuel cell 8, and
At its base end, a fuel pressure sensor 32 for measuring the pressure of the filled fuel is interposed. On the other hand, a low-pressure safety valve 34 that opens when the fuel pressure becomes equal to or higher than a predetermined value is interposed in the low-pressure pipe 22 downstream of the regulator 16.

Also, as a feature of the present invention, a bypass pipe 36 (bypass passage) for communicating the upstream side and the downstream side of the main stop valve 12 so as to bypass the main stop valve 12 is provided with a high pressure pipe 14.
Connected to. The bypass pipe 36 is provided with a manual opening / closing valve 38 for manually opening and closing the fuel passage. further,
In the vicinity of the main stop valve 12, a differential pressure sensor 40 (differential pressure detecting means) for detecting a fuel pressure difference ΔP [Pa] on the upstream side and the downstream side is disposed. Fuel pressure difference Δ from differential pressure sensor 40
P is input to a control unit 42 containing a microcomputer. In the control unit 42, the input fuel pressure difference ΔP is set to a predetermined value (for example, 20
0 [kPa]) or less, control is performed to turn on a notification lamp 44 (notification means) provided near the driver's seat.

It should be noted that, instead of the lighting control of the notification lamp 44 by the control unit 42, a differential pressure sensor that short-circuits the output terminals when the fuel pressure difference ΔP becomes equal to or less than a predetermined value may be used. Alternatively, for example, it may be displayed on a liquid crystal display device, or may be notified by sound or buzzer. According to the fuel supply device having such a configuration, the following can be performed to start the CNG engine in a state where the fuel pressure difference ΔP on the upstream and downstream sides of the main stop valve 12 is large. That is, prior to starting the engine, the manual open / close valve 38 interposed in the bypass pipe 36 is opened to open the bypass pipe 36. Then, the upstream side and the downstream side of the main stop valve 12 communicate with each other, the fuel on the upstream side flows into the downstream side due to the fuel pressure difference, and the fuel pressure difference ΔP
Decreases in a short time.

At this time, when the fuel pressure difference ΔP becomes equal to or less than a predetermined value, a notification lamp 44 provided near the driver's seat is turned on. Therefore, the driver can recognize that the condition that the main valve of the main stop valve 12 is opened, that is, the condition that the main stop valve 12 is fully opened is satisfied. In addition, the manual on-off valve 38 can be opened only for a minimum necessary time, and the time required to start traveling can be minimized.

After the manual on-off valve 38 is closed and the bypass pipe 36 is closed, for example, the ignition switch is operated to a start position to start the CNG engine. Then, since the fuel pressure difference ΔP between the upstream side and the downstream side of the main stop valve 12 is equal to or less than a predetermined value, the main valve of the main stop valve 12 opens at the same time when the engine is started, and sufficient fuel supply to the CNG engine is performed. I can run immediately.
For this reason, it is possible to immediately drive immediately after the engine is started, and it is possible to improve running performance.

The manual opening / closing valve 38 may be operated at the time of idling immediately after the start of the engine. In addition, the manual on-off valve 3
The operation unit 8 may be configured such that its operation unit is provided in the vicinity of the driver's seat via, for example, a cable or a link mechanism so that the operation unit 8 can be remotely operated from the driver's seat. In this case, the driver
The bypass pipe 36 can be opened and closed while sitting in the driver's seat, and the labor required for starting the engine can be reduced.

[0018]

As described above, according to the first aspect of the present invention, if the bypass passage is opened by opening the manual opening / closing valve prior to starting the engine, the upstream side and the downstream side of the main stop valve are provided. And the fuel pressure difference decreases in a short time. For this reason, since the main stop valve is fully opened simultaneously with the start of the engine, it is possible to immediately drive immediately after the start of the engine, and it is possible to improve the running performance.

According to the second aspect of the invention, the driver:
The bypass passage can be opened and closed while sitting in the driver's seat, and the labor required for starting the engine can be reduced. According to the invention described in claim 3, the driver can recognize that the condition that the main stop valve is fully opened is satisfied. Further, the time until the start of traveling is minimized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fuel supply device according to the present invention.

FIG. 2 is a configuration diagram of a fuel supply device according to the related art.

FIG. 3 is a sectional view of a main part of a main stop valve.

[Explanation of symbols]

 Reference Signs List 10 cylinder 12 main stop valve 14 high pressure pipe 16 regulator 36 bypass pipe 38 manual open / close valve 40 differential pressure sensor 42 control unit 44 notification light

Claims (3)

[Claims] A fuel container for storing gaseous fuel; a regulator for regulating the gaseous fuel to a predetermined pressure; a fuel passage for guiding gaseous fuel stored in the fuel container to a regulator; A main stop valve that opens and closes the passage, a bypass passage that connects the upstream side and the downstream side so as to bypass the main stop valve, and a manual open / close valve that manually opens and closes the bypass passage. A fuel supply device for a gas engine. 2. The fuel supply system for a gas engine according to claim 1, wherein said manual on-off valve can be remotely operated from a driver's seat. 3. A pressure difference detecting means for detecting a fuel pressure difference between an upstream side and a downstream side of the main stop valve, and when the fuel pressure difference detected by the pressure difference detecting means becomes a predetermined value or less. 3. An informing means for informing that effect, further comprising:
A fuel supply device for a gas engine according to claim 1.