JP2002295311A - Fuel supply device for gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve convenience for operation of a vehicle, by reporting a condition capable of 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) as gas fuel, 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 differential pressure sensor 36 detecting a fuel pressure difference ΔP between the upstream/downstream of the main stop valve 12, and a control unit 38 lighting a report lamp 40 provided in the vicinity of a driver's seat when the fuel pressure difference ΔP is generated at a prescribed value or less. In this way thus constituted, a driver can recognize the main stop valve 12 fully opened by lighting of the report lamp 40, that is, a vehicle placed in a condition capable of running.

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 facilitating vehicle operation.

[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. 8, 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. 9, when the coil 2A is not energized (the engine is stopped), the plunger 2B is pressed by the spring 2C, the pilot valve 2D and the main valve 2E are seated, and further, 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.

[0005] In view of the above problems, the present invention provides a gas engine fuel supply device that informs that the vehicle can run after the engine is started, and improves the convenience of vehicle operation. The purpose is to:

[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,
The fuel supply device for a gas engine includes a main stop valve that opens and closes the fuel passage in conjunction with the gas engine, and an operation state notification unit that notifies an operation state of the main stop valve. .

According to this configuration, when the gas engine is started, the gaseous fuel stored in the fuel container is guided to the regulator through the fuel passage, where the gaseous fuel is regulated to a predetermined pressure, and then the gaseous engine is started. Supplied to At this time, when the fuel pressure difference between the upstream side and the downstream side is large, the main stop valve that opens and closes the fuel passage is not fully opened, and the output for traveling due to insufficient fuel supply cannot be obtained. After a certain period of time has elapsed since the start of the gas engine, the fuel pressure difference between the upstream side and the downstream side of the main stop valve becomes small, and the main stop valve is fully opened, so that the vehicle can run. Since the operating state of the main stop valve is notified by the operating state notifying means, the driver can recognize that the main stop valve has been fully opened, that is, that the vehicle can run.

[0008] In the second aspect of the present invention, the operating state notifying means includes 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 the pressure difference detecting means detects the fuel pressure difference. Notification means for notifying that the main stop valve has been fully opened when the fuel pressure difference has become equal to or less than a predetermined value. When the fuel pressure difference between the upstream side and the downstream side becomes equal to or less than a predetermined value, it is notified that the main stop valve has been fully opened.
Therefore, the operation state of the main stop valve is notified by a simple configuration, and a decrease in the reliability and durability of the device is prevented.

In the invention according to claim 3, the operating state notifying means includes a control amount detecting means for detecting a control amount of the main stop valve, and the control amount detecting means based on the control amount detected by the control amount detecting means. An operating state determining means for determining an operating state of the main stop valve, and a notifying means for notifying when the operating state determining means determines that the main stop valve has been fully opened. It is characterized by the following.

With this configuration, when it is determined that the main stop valve has been fully opened based on the control amount of the main stop valve, the fact is notified. Therefore, by changing the determination logic based on the control amount, it is possible to determine the operation state of the main stop valve having different characteristics, and the versatility is given to hardware. In the invention described in claim 4, the operating state notifying means includes a valve position detecting means for detecting a valve position of the main stop valve, and the main stop valve based on a valve position detected by the valve position detecting means. Operating state judging means for judging the operating state of the main stop valve, and a notifying means for notifying that the main stop valve has been fully opened by the operating state judging means. And

According to this configuration, when it is determined that the main stop valve is fully opened based on the valve position of the main stop valve, the fact is notified. Therefore, the operation state of the main stop valve is directly determined based on the valve position, and thus the determination accuracy is improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. FIG. 1 shows a first embodiment of a fuel supply device for a gas engine according to the present invention (hereinafter referred to as “fuel supply device”).
1 shows an embodiment. CNG stored in a cylinder 10 as a fuel container is supplied to a high pressure pipe 14 in which a main stop valve 12 is interposed.
It is guided to the regulator 16 via the (fuel passage).
The CNG guided to the regulator 16 is regulated to a predetermined pressure while preventing supercooling by the engine cooling water, and is supplied to the fuel injection valve via a low pressure pipe 22 provided with a fuel filter 18 and a low pressure fuel cutoff valve 20. 24. CNG guided to the fuel injection valve 24 depends on the engine operating state.
The fuel is injected and supplied into an intake passage (not shown).

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.

Further, as a feature of the present invention, near the main stop valve 12, a fuel pressure difference ΔP [Pa] between an upstream side and a downstream side thereof is provided.
Is provided with a differential pressure sensor 36 (pressure difference detecting means) for detecting the pressure. The fuel pressure difference ΔP from the differential pressure sensor 36 is input to a control unit 38 containing a microcomputer. In the control unit 38, when the input fuel pressure difference ΔP becomes equal to or less than a predetermined value (for example, 200 [kPa]), an alarm lamp 40 provided near the driver's seat.
The control for turning on (notifying means) is executed.

It should be noted that, instead of the lighting control of the notification lamp 40 by the control unit 38, a differential pressure sensor that short-circuits between the output terminals when the fuel pressure difference ΔP becomes equal to or less than a predetermined value may be used. Further, instead of the notification light 40, 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, when the ignition switch is operated to the power supply position in order to start the CNG engine, the main stop valve 12
, And the pilot valve having a small opening area is opened. When the pilot valve opens, the CNG upstream of the main stop valve 12 flows downstream through the opening of the pilot valve, and the fuel pressure on the downstream gradually increases. When the fuel pressure difference ΔP between the upstream side and the downstream side of the main stop valve 12 becomes equal to or less than a predetermined value, the main valve having a large opening area is opened, and the notification light 40 provided near the driver's seat is turned on. If the ignition switch is operated to the start position at the time when the notification light 40 is turned on, CNG is injected and supplied from the fuel injection valve 24 to the intake passage, and the CNG engine starts in a state where the vehicle can run immediately.

On the other hand, when the ignition switch is operated to the starting position to immediately start the CNG engine,
At the same time as the cranking is started, the main stop valve 12 is energized, and the pilot valve having a small opening area is opened. When the pilot valve opens, CNG on the upstream side of the main stop valve 12 is opened.
Flows out to the downstream side through the opening of the pilot valve, and is injected and supplied from the fuel injection valve 24 into the intake passage.
The NG engine starts. At this time, the CNG downstream of the main stop valve 12 is consumed by the CNG engine. The pressure rises slowly. When the fuel pressure difference ΔP between the upstream side and the downstream side of the main stop valve 12 becomes equal to or less than a predetermined value, the main valve having a large opening area is opened, and the notification lamp 40 is opened.
Lights up.

Therefore, the driver can recognize that the main stop valve 12 is fully opened, that is, the vehicle can run by turning on the notification light 40. For example, the engine is not sufficiently blown up. It is possible to avoid starting traveling in an unfavorable state, and to facilitate the operation of the vehicle. in this case,
The fact that the main stop valve 12 has been fully opened is notified by a simple configuration, so that it is possible to prevent a decrease in the reliability and durability of the device.

FIG. 2 shows a second embodiment of the fuel supply device. In addition, about the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching | subjecting the same code | symbol (the same below). An ammeter 44 (control amount detecting means) for measuring a current I [A] as a control amount of the main stop valve 12 is interposed in the power supply line 42 to the main stop valve 12. The current I from the ammeter 44 is
It is input to the control unit 38. In the control unit 38, the operation state of the main stop valve 12 is determined based on the input current I, and lighting control of the notification lamp 40 is performed according to the determination result.

The fuel pressure P and the current I on the downstream side of the main stop valve 12
And a relationship as shown in FIG. That is,
As time elapses after the ignition switch is turned on, the fuel pressure P downstream of the main stop valve 12 gradually increases, but the current I drops momentarily when the fuel pressure P becomes substantially equilibrium. By detecting this decrease in the current I, the main stop valve 1
It can be detected that the second main valve is opened, that is, the main stop valve 12 is fully opened.

FIG. 4 shows the control contents of the control unit 38 which is started at the same time as the start of the CNG engine in the second embodiment. Step 1 (“S
1 ". In the same applies hereinafter), the current I _n from the ammeter 44 is detected. In step 2, the time t _n is detected by the timer mechanism.

In step 3, the current I
_{n + 1} is detected. In Step 4, the time t _{n + 1} is detected by the clock mechanism. In step 5, the current difference dI
Is calculated. In step 6, a time difference dt is calculated. In step 7, it is determined whether the current change rate dI / dt is greater than a predetermined value ΔI. The predetermined value ΔI is a threshold value for determining whether or not the main valve of the main stop valve 12 has been opened, and is set to an appropriate value based on, for example, a characteristic diagram shown in FIG. If the current change rate dI / dt is larger than the predetermined value ΔI, the process proceeds to step 8 (Ye
s), the notification light 40 provided near the driver's seat is turned on. On the other hand, if the current change rate dI / dt is equal to or smaller than the predetermined value ΔI, the process proceeds to step 9 (No).

[0023] In step 9, comprising the detection of the next current I _{n + 1,} the current I _n is updated by the current I _{n + 1.} In step 10, in preparation for the detection of the next time point t _{n + 1,} after the time t _n is updated by the time t _{n + 1,} the flow returns to step 3. Note that the processing in steps 1 to 7, step 9, and step 10 implements an operation state determination unit according to claim 3.

According to the fuel supply device having such a configuration, when the current change rate dI / dt becomes larger than the predetermined value ΔI, the main valve of the main stop valve 12 is opened, that is, the main stop valve 12 is fully opened. And the notification lamp 40 is turned on. In this case, since the operation state of the main stop valve 12 is determined based on the control amount, it is possible to determine the operation state of the main stop valve having different characteristics by changing the determination logic. Can be given versatility. Note that other functions and effects are the same as those of the first embodiment, and a description thereof will be omitted.

FIGS. 5 to 7 show a third embodiment of the fuel supply device. As shown in FIG. 6 or FIG. 7, the main stop valve 12 has a gap sensor 46 for indirectly detecting that the main valve 12B has been opened via the position of the plunger 12A.
(Valve position detecting means) is incorporated. Gap sensor 46
Is desirably configured such that when the main valve 12B is opened, a short circuit occurs between output terminals (not shown). The notification light 40 is connected to the output terminal of the gap sensor 46. The gap sensor 46 also has a function as an operation state determination unit according to the fourth aspect.

According to the fuel supply device having such a configuration, when the main stop valve 12 is energized and the main valve 12B is opened, the state is detected via the position of the plunger 12A. Then, the notification lamp 40 is turned on due to a short circuit between the output terminals of the gap sensor 46. In this case, since the operation state of the main stop valve 12 is directly determined based on the position of the plunger 12A, the determination accuracy can be improved. Note that other functions and effects are the same as those of the first and second embodiments, and a description thereof will be omitted.

[0027]

As described above, according to the first aspect of the present invention, the driver can recognize that the vehicle can run, for example, in a state where the gas engine is not sufficiently blown up. Starting traveling can be avoided, and convenience in vehicle operation can be achieved. According to the second aspect of the present invention, since the operating state of the main stop valve is notified by a simple configuration, it is possible to prevent a decrease in the reliability and durability of the device.

According to the third aspect of the present invention, it is possible to determine the operating state of the main stop valve having different characteristics by changing the determination logic based on the control amount, and to provide versatility to hardware. can do. According to the fourth aspect of the present invention, since the operation state of the main stop valve is directly determined based on the valve position, the determination accuracy can be improved.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing a second embodiment of a fuel supply device according to the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a fuel pressure and a current downstream of a main stop valve.

FIG. 4 is a flowchart showing a process for determining an operation state of a main stop valve.

FIG. 5 is a configuration diagram showing a third embodiment of a fuel supply device according to the present invention.

FIG. 6 is a configuration diagram showing an example of a main stop valve incorporating a gap sensor.

FIG. 7 is a configuration diagram showing another example of a main stop valve incorporating a gap sensor.

FIG. 8 is a configuration diagram of a fuel supply device according to the related art.

FIG. 9 is an explanatory view of the operation of the main stop valve.

[Explanation of symbols]

 Reference Signs List 10 cylinder 12 main stop valve 14 high pressure pipe 16 regulator 36 differential pressure sensor 38 control unit 40 indicator light 44 ammeter 46 gap sensor

Claims (4)

[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 fuel supply device for a gas engine, comprising: a main stop valve that opens and closes a passage; and an operation state notification unit that notifies an operation state of the main stop valve. 2. The operating state notifying means includes: 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 a fuel pressure difference detected by the pressure difference detecting means being a predetermined value. The fuel supply device for a gas engine according to claim 1, further comprising: notification means for notifying that the main stop valve has been fully opened when the following occurs. 3. The operating state notifying means includes: a control amount detecting means for detecting a control amount of the main stop valve; and a control amount detected by the control amount detecting means.
Operating state determining means for determining an operating state of the main stop valve; and notifying means for notifying when the operating state determining means determines that the main stop valve has been fully opened. The fuel supply device for a gas engine according to claim 1, wherein: 4. The operating state notifying means includes: a valve position detecting means for detecting a valve position of the main stop valve; and a valve position detected by the valve position detecting means.
Operating state determining means for determining an operating state of the main stop valve; and notifying means for notifying when the operating state determining means determines that the main stop valve has been fully opened. The fuel supply device for a gas engine according to claim 1, wherein: