JPH0988724A - Fuel supply system of compressed natural gas automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly prevent malfunction of an excess flow valve and sufficiently supply natural gas of fuel. SOLUTION: A pilot kick type emergency cutoff valve for equalization 10 integrally provided in a conduit run between an excess flow preventing valve 2 and a pressure reducing valve 9 to work to open by an engine starting signal from a controller 12 as an emergency cutoff valve to open the conduit run while driving an engine by a command signal from the controller 12 and to close the conduit run at the time of stopping the engine or at the time of emergency and an emergency cutoff valve for fuel supply 8 to work to open by delaying for a specified period of time after the emergency cutoff valve for equalization 10 by a delay signal from the controller 12 are provided. This is a fuel supply system of a compressed natural gas automobile on which the emergency cutoff valve for fuel supply 8 is integrally provided in a main conduit run 6 communicating the excess flow preventing valve 2 and the pressure reducing valve 9 to each other, the emergency cutoff valve for equalization 10 is integrally provided in a by-pass conduit run 7 communicating the upstream and the downstream of the emergency cutoff valve 8 for fuel supply to each other and an orifice 11 to work to throttle is integrally provided in a by-pass upstream conduit run 7a on the upstream side of the emergency cutoff valve 10 for equalization.

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 compressed natural gas vehicle using compressed natural gas as a fuel for an engine.

[0002]

2. Description of the Related Art In recent years, natural gas, which is a clean energy source with little air pollution, has been attracting attention as an energy source for replacing petroleum, and so-called compressed natural gas automobiles that use this natural gas as a fuel for an engine are also being used. It is spreading rapidly.

The compressed natural gas vehicle is equipped with a unique fuel supply device different from that for liquid fuel such as gasoline because the high pressure compressed natural gas stored in the fuel container is used as the engine fuel. The general structure of this fuel supply system is that a pipe from the fuel container of compressed natural gas to the venturi mixer installed in the intake system of the engine is equipped with an overflow prevention valve, an orifice, an emergency shutoff valve, a pressure reducing valve, etc. It was installed.

The fuel container stores natural gas compressed to a high pressure of 200 kg / cm ² , and there is a danger of a large amount of natural gas flowing out of the fuel container at one time, so the flow rate of natural gas is excessive. In this case, the overflow prevention valve shuts off the pipeline to ensure safety. The emergency shutoff valve is of a pilot kick type that opens a pipeline during engine startup and operation and closes the pipeline when the engine is stopped or in an emergency in response to a command signal from the controller. Since there is a large pressure difference between the upstream side and the downstream side of this emergency shutoff valve, when the main valve of the emergency shutoff valve opens, a large amount of natural gas momentarily flows and the above-mentioned overflow prevention valve May malfunction. Therefore, in order to prevent this malfunction, an orifice is provided in the conduit between the overflow prevention valve and the emergency shutoff valve. The pressure reducing valve gradually reduces the pressure of the high-pressure compressed natural gas passing through the emergency shutoff valve, and the natural gas whose pressure has been reduced to around atmospheric pressure is mixed with air by the venturi mixer and supplied to the engine.

[0005]

By the way, in the above-described conventional fuel supply device for a general compressed natural gas vehicle, the smaller the diameter of the orifice, the more reliably the malfunction of the overflow prevention valve can be prevented. As the diameter of the orifice becomes smaller, the supply of natural gas, which is the fuel, becomes insufficient,
This causes inconveniences such as deterioration of vehicle acceleration performance and deterioration of exhaust gas emissions.

Therefore, an object of the present invention is to provide a fuel supply device for a compressed natural gas vehicle, which can surely prevent malfunction of the overflow prevention valve and can sufficiently supply natural gas as fuel. .

[0007]

As a means for achieving this object, the present invention provides a large amount of fuel gas from a fuel container of compressed natural gas to a pipe line from a fuel container of the engine to a venturi mixer installed in the intake system of the engine. Is installed on the downstream side of the overflow prevention valve that shuts off the pipeline when the fuel flows, and opens the pipeline when the engine is operating in response to a command signal from the controller. In a fuel supply device for a compressed natural gas vehicle, which includes an emergency shutoff valve that closes a passage and a pressure reducing valve that is disposed downstream of the emergency shutoff valve and that reduces the pressure of the fuel gas,
As the emergency cutoff valve, a pilot kick system pressure equalization emergency cutoff valve that opens by an engine start signal from the controller, and fuel that opens after a predetermined time from the pressure equalization emergency cutoff valve by a delay signal from the controller An emergency shutoff valve for supply is provided, and the emergency shutoff valve for fuel supply is provided in the main pipe line connecting the overflow prevention valve and the pressure reducing valve, and the emergency shutoff valve for pressure equalization is the emergency shutoff for fuel supply. It is characterized in that the valve is interposed in a bypass pipe line that communicates the upstream side and the downstream side of the valve, and a throttling action is given to the bypass pipe line upstream of the pressure equalizing emergency cutoff valve.

Here, as means for applying a throttling action to the bypass pipe upstream of the pressure equalizing emergency cutoff valve, an orifice is provided in the upstream bypass pipe, or the upstream bypass pipe is disconnected. Another feature is that the area is set small.

[0009]

In the present invention employing such means, the pilot kick type pressure equalizing emergency cutoff valve opens the bypass passage by the engine start signal from the controller when the engine is started. Therefore, the high-pressure compressed natural gas stored in the fuel container is supplied from the overflow prevention valve to the venturi mixer installed in the intake system of the engine through the bypass line and the pressure reducing valve, and the engine is started. At that time, since the bypass action on the upstream side of the pressure equalization emergency cutoff valve is given a throttling action by an orifice, etc., the flow rate of the compressed natural gas does not become excessive and the malfunction of the overflow prevention valve is ensured. To be prevented.

A delay signal from the controller causes the fuel supply emergency cutoff valve to open the main pipeline after a delay of a predetermined time from the opening operation of the pressure equalization emergency cutoff valve. At this time, the insides of the main pipelines on the upstream side and the downstream side of the fuel supply emergency cutoff valve are already in communication by the bypass passages and are in a substantially equal pressure state. Therefore, even if the main pipeline opens, the flow rate of compressed natural gas will not become too large and the overflow prevention valve will not malfunction.While the engine is operating, a sufficient amount of natural gas will flow to the Venturi mixer through the main pipeline. Supplied.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be specifically described with reference to the drawings. In FIG. 1, which shows a schematic configuration of a fuel supply device for a compressed natural gas vehicle, reference numeral 1
Is a fuel container storing high-pressure compressed natural gas of about 200 kg / cm ² , reference numeral 2 is an overflow prevention valve connected to the fuel container 1, reference numeral 3 is installed in the intake pipe 5 of the engine 4, and 2 shows a Venturi mixer mixing with air.

The overflow prevention valve 2 automatically closes when the flow rate of the compressed natural gas flowing out of the fuel container 1 becomes excessive. The overflow prevention valve 2 and the venturi mixer 3 are main pipes. A bypass pipe 7 having a smaller pipe diameter than that of the main pipe 6 is connected in parallel with the main pipe 6 in the middle thereof.

In the main conduit 6, an emergency shutoff valve 8 for fuel supply is provided between the branch point and the assembly point of the bypass conduit 7.
Further, a pressure reducing valve 9 for gradually reducing the pressure of the high pressure compressed natural gas to substantially the atmospheric pressure is provided downstream of the gathering point. On the other hand, a pressure equalizing emergency shutoff valve 10 is provided in the bypass line 7, and the bypass line 7
An orifice 11 for restricting the flow rate of the compressed natural gas and preventing the malfunction of the overflow prevention valve 2 is provided in the bypass upstream pipeline 7a upstream of the pressure equalizing emergency shutoff valve 10.

The fuel supply emergency cutoff valve 8 is a normal solenoid valve whose valve body is opened and closed immediately by controlling energization of the solenoid. On the other hand, the pressure equalizing emergency shutoff valve 10
Is a so-called pilot kick type solenoid valve that can be surely opened even when the pressure difference between the inlet side and the outlet side is large. That is, in the pressure equalizing emergency cutoff valve 10, the pilot valve body having a small pressure receiving area is opened to a small size in the first stage by energization of the solenoid, and the inlet side and the outlet side are communicated with each other through the pilot passage. When the pressure difference with the side becomes smaller, the main valve body as well as the pilot valve body open greatly to connect the inlet side and the outlet side.

Here, the fuel supply emergency cutoff valve 8 and the pressure equalization emergency cutoff valve 10 are controlled to open and close by command signals from the controller 12 as shown in FIG. That is, the pressure equalizing emergency cutoff valve 10 is energized by the engine start signal output from the controller 12 to open the bypass conduit 7, and the fuel supply emergency cutoff valve 8 is delayed by the delay signal output from the controller 12. Valve 1
The main conduit 6 is opened with a delay of 2-3 seconds from the valve opening operation of 0.

The fuel supply emergency cutoff valve 8 and the pressure equalization emergency cutoff valve 10 are immediately closed by energization by an engine stop signal or an emergency signal output from the controller 12 to close the valve. ing. Also,
To the controller 12, for example, an on / off signal of an ignition key of a vehicle is input as an engine start signal and a stop signal, and a detection signal of a crank shaft stop sensor for detecting a stop of a crank shaft of an engine is used as an emergency signal, A detection signal from an impact sensor that detects a vehicle collision is input.

In the fuel supply system for a compressed natural gas vehicle of one embodiment configured as described above, for example, when the ignition key switch is turned on, the on signal is input to the controller 12, so that the controller 12 immediately operates. The engine start signal is output to the pressure equalizing emergency cutoff valve 10, and the delay signal is delayed by 2 to 3 seconds and the fuel supply emergency cutoff valve 8 is output.
Output to Therefore, when the engine is started, the pressure-equalizing emergency shutoff valve 10 opens in the first stage to open the bypass pipe line 7,
Subsequently, the fuel supply emergency cutoff valve 8 is opened with a delay of 2 to 3 seconds to open the main pipe line 6.

When the pressure-equalizing emergency shutoff valve 10 opens the bypass line 7, the high-pressure compressed natural gas stored in the fuel container 1 is passed from the overflow prevention valve 2 to the upstream side of the main line 6 to bypass the bypass line 7. Inflow into 7. Since the flow rate of this high-pressure compressed natural gas is regulated by passing through the orifice 11 provided in the bypass upstream pipe line 7a, the overflow prevention valve 2 does not close due to a malfunction. Therefore, the high-pressure compressed natural gas continuously flows through the bypass line 7 and reaches the pressure reducing valve 9. Then, the natural gas whose pressure is reduced to near atmospheric pressure by the pressure reducing valve 9 is supplied to the venturi mixer 3 via the downstream side of the main pipe line 6, whereby the engine 4 is started.

Next, the fuel supply emergency cutoff valve 8 opens the main pipe line 6. At this time, the upstream side and the downstream side of the fuel supply emergency cutoff valve 8 are connected by the bypass pipe line 7. Since the fuel supply emergency cutoff valve 8 is a normal solenoid valve, the fuel supply emergency cutoff valve 8 can be smoothly opened. When the main pipe line 6 is opened by the opening operation of the fuel supply emergency cutoff valve 8, the high pressure compressed natural gas from the overflow prevention valve 2 flows into the main pipe line 6 and the fuel supply emergency cutoff valve 8 is opened. Pass through. At that time, since the upstream side and the downstream side of the fuel supply emergency cutoff valve 8 are in a substantially equal pressure state,
The flow rate of compressed natural gas does not become momentarily excessive,
The overflow prevention valve 2 does not close due to a malfunction. Therefore, the high-pressure compressed natural gas continuously flows through the main pipeline 6 to reach the pressure reducing valve 9, and the sufficient pressure of the natural gas reduced by the pressure reducing valve 9 to near atmospheric pressure is supplied to the venturi mixer 3. The operation of the engine 4 is continued.

As described above, while the engine 4 is operating, a sufficient amount of natural gas is supplied as fuel to the venturi mixer 3 through the main pipe 6, so that the acceleration performance of the vehicle is deteriorated due to insufficient fuel supply. , The emission of exhaust gas will not deteriorate.

When the ignition key switch is turned off, the off signal is input to the controller 12, so that the controller 12 immediately sends an engine stop signal to the fuel supply emergency cutoff valve 8 and the pressure equalization emergency cutoff valve 10. Output. Therefore, when the engine is stopped, both the fuel supply emergency cutoff valve 8 and the pressure equalization emergency cutoff valve 10 are closed to close the main pipe line 6 and the bypass pipe line 7 to prevent natural gas from flowing out to the venturi mixer 3. To do.

When the engine 4 is stopped due to some trouble or a vehicle has a collision accident, for example, a detection signal of a crankshaft stop sensor or an impact sensor is input to the controller 12 as an emergency signal, so that the controller 12 12 immediately sends an emergency signal to the fuel supply emergency shutoff valve 8
And output to the pressure equalizing emergency shutoff valve 10. Therefore, even in such an emergency, the fuel supply emergency cutoff valve 8 and the pressure equalization emergency cutoff valve 10 both close to close the main pipe line 6 and the bypass pipe line 7, and natural gas flows out to the venturi mixer 3. Prevent.

The bypass upstream pipe line 7a shown in FIG.
May be set to have a small cross-sectional area of its own channel so as to have a throttle action. In such a case, the orifice 1
1 can be omitted.

[0024]

As described above, in the present invention, when the engine is started, the pressure cut-off emergency cutoff valve opens the bypass passage by the engine start signal from the controller, and the compressed natural gas stored in the fuel container is discharged from the overflow prevention valve. Bypass line,
The engine is started by being supplied to the Venturi mixer installed in the intake system of the engine via the pressure reducing valve.
Then, after delaying the opening operation of the pressure equalizing emergency shutoff valve for a predetermined time,
Due to the delay signal from the controller, the fuel supply emergency shutoff valve opens the main pipe, so that the compressed natural gas from the overflow prevention valve is supplied to the Venturi mixer via the main pipe and pressure reducing valve, and the engine is operated. Continued.

Here, since the bypass passage upstream of the pressure equalizing emergency cutoff valve is given a throttling action by an orifice or the like, the flow rate of the compressed natural gas becomes excessive when the pressure equalizing emergency cutoff valve opens the bypass passage. It never becomes. Also,
When the emergency shutoff valve for fuel supply opens the main pipeline, the main pipelines on the upstream and downstream sides are already connected by the bypass passage and are in a substantially equal pressure state. Will never be too large. Therefore, according to the present invention, it is possible to reliably prevent the malfunction of the overflow prevention valve.

Further, while the engine is in operation, a sufficient amount of natural gas can be supplied to the Venturi mixer through the main pipe line to prevent deterioration of acceleration performance of the vehicle and deterioration of exhaust gas emission. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a fuel supply device for a compressed natural gas vehicle according to the present invention.

FIG. 2 is a time chart of the on / off operation of the fuel supply emergency cutoff valve and the pressure equalization emergency cutoff valve in one embodiment.

[Explanation of symbols]

 1 Fuel Container 2 Overflow Prevention Valve 3 Venturi Mixer 4 Engine 5 Intake Pipe 6 Main Pipeline 7 Bypass Pipeline 7a Bypass Upstream Pipeline 8 Fuel Supply Emergency Shutoff Valve 9 Pressure Reduction Valve 10 Equalization Emergency Shutoff Valve 11 Orifice 12 Controller

Claims (3)

[Claims] 1. A pipeline from a compressed natural gas fuel container to a venturi mixer installed in an intake system of an engine,
An overflow prevention valve that shuts off the pipeline when a large amount of fuel gas flows out from the fuel container, and is arranged downstream of this overflow prevention valve.The pipeline is opened during engine operation in response to a command signal from the controller. A fuel supply device for a compressed natural gas vehicle in which an emergency shutoff valve that closes a pipeline when the engine is stopped or in an emergency and a pressure reducing valve that is disposed downstream of the emergency shutoff valve to reduce the pressure of fuel gas are interposed In the above, as the emergency shutoff valve, a pilot kick system pressure equalization emergency shutoff valve that opens by an engine start signal from the controller, and a delay signal from the controller opens the pressure equalization emergency shutoff valve by a predetermined time after opening. An emergency shutoff valve for fuel supply is provided, and the emergency shutoff valve for fuel supply is provided in the main conduit that connects the overflow prevention valve and the pressure reducing valve, The emergency shutoff valve for use is provided in the bypass pipeline that connects the upstream side and the downstream side of the fuel supply emergency shutoff valve, and the bypass pipeline on the upstream side of the pressure equalization emergency shutoff valve has a throttling action. A fuel supply device for a compressed natural gas vehicle characterized by the above. 2. The fuel supply apparatus for a compressed natural gas vehicle according to claim 1, wherein an orifice is provided in the bypass pipe line on the upstream side of the pressure equalizing emergency cutoff valve so as to perform a throttle action. 3. The fuel supply system for a compressed natural gas vehicle according to claim 1, wherein the bypass pipe upstream of the pressure equalizing emergency cutoff valve has a small pipe cross-sectional area and acts as a throttle. .