JPH03213651A - Fuel feeding device of lpg engine - Google Patents

Abstract

PURPOSE:To make a special excess flow check valve unnecessary to prepare and to simplify the structure by setting a flow meter at the upper stream side of an emergency cutoff valve of a fuel passage, and shutting the emergency cutoff valve when the fuel flow detected by the flow meter is less than a specific flow. CONSTITUTION:In a fuel passage 1 from an LPG tank 2 to a vaporizer 7, a manual changeover valve 3, an emergency cutoff valve 4, and an electromagnetic changeover valve 6 are provided in order, and after the liquid LPG is regulated into a gas LPG of a specific pressure in the vaporizer 7, it is delivered to a mixer 9 to mix with the air, and the mixture gas is fed to an engine 11. The emergency cutoff valve 4 and the electromagnetic changeover valve 6 are linked to a key switch 12, and they are opened in the operation, while they are closed when the engine is stopped. And a flow meter 35 is composed of a differential pressure generator 36 which consists of an orifice, and a differential pressure detector 37, set at the upper stream side of the changeover valve 3 of the fuel passage 1, and the emergency cutoff valve 4 is controlled to be closed when the fuel flow is less than a specific flow, so as to exercise the excess flow preventive function.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel supply system for an engine that uses LPG (liquefied petroleum gas) as fuel, and more specifically to an emergency shutoff valve installed in a fuel passage from an LPG tank to a vaporizer. This invention relates to a fuel supply system that combines the functions of an overflow prevention valve and an overflow prevention valve into a single product.

[Prior Art] As shown in FIG. 3, the fuel system of an LPG engine such as a commercial vehicle converts high-pressure liquid LPG sent from an LPG tank 51 to a vaporizer 53 through a fuel passage 52 to gaseous LPG at a predetermined pressure. The fuel is adjusted and sent to a mixer 55 through a fuel conduit 54, mixed with air, and supplied to an engine 57 through an intake manifold 56.

The fuel passage 52 includes an overflow prevention valve 58 that operates to shut off fuel when liquid LPG flows over a certain flow rate, and a manual on-off valve 5.
9. An electromagnetic on-off valve 60 is provided which opens and sends fuel to the vaporizer 53 when the engine is running in conjunction with the key switch 62, but closes to cut off fuel when the engine is stopped, and a filter (not shown). Furthermore, for commercial vehicles, from October 1989, the manual opening/closing valve 53 must be 40 cm
It is now mandatory to install an emergency shutoff valve 61 that opens and closes simultaneously with the electromagnetic on-off valve 60 within the following locations:

Here, looking at the overflow prevention valve 58 and the manual on-off valve 59, the overflow prevention valve 58 is opened by back pressure and spring force against the pressure of liquid LPG flowing out from the LPG tank 51. Therefore, once the valve is closed, the LP of the fuel passage 52
Since G is consumed and there is no back pressure, the valve remains closed, and is pushed open when the manual on-off valve 59 is operated to the closed position. That is, when the excessive flow prevention valve 58 is activated, it cannot be reset unless the driver operates the manual on-off valve 59, which is extremely inconvenient.

Furthermore, an overflow prevention valve 58, a manual opening/closing valve 59, an emergency shutoff valve 6
1 is installed near the LPG tank 51, so in the case of a car, each independent part must be stored in the trunk, which tends to create a space problem.

[Problems to be Solved by the Invention] The present invention is extremely inconvenient because when the overflow prevention valve installed in the fuel system of the LPG engine is activated, it cannot be reset without operating the manual on-off valve. Based on the law 1. The purpose of this project is to solve the above-mentioned problem that installing an emergency shut-off valve in the trunk of a car tends to create a space problem when it is stored in the trunk of a car. For management purposes, it is possible to restore automatically without having to restore manually.
An object of the present invention is to provide a fuel supply device for an LPG engine that is convenient in handling and can be easily installed even in a narrow space.

[Means for Solving the Problems] The present invention includes a manual on-off valve, an emergency cut-off valve, and an electromagnetic on-off valve in the fuel passage from the LPG tank to the vaporizer, and the emergency cut-off valve and the electromagnetic on-off valve are linked to a key switch. In order to solve the above-mentioned problem of the LPG engine fuel supply system which opens and closes at the same time, the following measures were taken.

That is, a flow rate measuring device is installed in the fuel passage upstream of the emergency shutoff valve, and a flow rate determination device determines whether the fuel flow rate is above or below a certain level based on an electric signal generated by the flow rate measuring device; and a controller that operates to cut off energization to the electromagnetic coil of the emergency cutoff valve in response to a drive signal issued by the flow rate determiner when the flow rate is above a certain level, and the fuel passage has an independent overflow prevention valve. The configuration is such that it does not have

[Operation] When fuel flows from the LPG tank toward the vaporizer at a flow rate greater than a certain level, the flow rate determiner issues a drive signal to the controller based on the electrical signal from the flow meter to cut off the current. As a result, the emergency shutoff valve closes, closing the fuel passage and performing an overflow prevention function. When the drive signal is released, when electric current is supplied, the emergency shutoff valve opens and the overflow prevention function is canceled. It happens.

[Example] The present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an example of a fuel supply system according to the present invention, which shows an example of a fuel supply system from an LPG tank 2 to a vaporizer 7.
A manual on-off valve 3, an emergency shut-off valve 4, and an electromagnetic on-off valve 6 are installed in this order in the fuel passage 1 leading to the fuel passage 1, and the liquid LPG sent from the LPG tank 2 to the vaporizer 7 is converted into gas L at a predetermined pressure.
The fuel is adjusted to PG and sent to a mixer 9 through a fuel conduit 8,
The air is mixed with the engine 11 by the intake manifold 1o.
A manual on-off valve 3 and an emergency shut-off valve 4 are installed in the trunk of the automobile near the LPG tank 2, and an electromagnetic on-off valve 6 is installed in the engine room near the vaporizer 7. Emergency shutoff valve 4
The electromagnetic on-off valve 6 and the electromagnetic on-off valve 6 operate simultaneously in conjunction with the key switch 12 so that they are opened to send fuel to the vaporizer 7 while the engine is running, but are closed to cut off the fuel when the engine is stopped.

The emergency shutoff valve 4 has the same configuration as the electromagnetic on-off valve 6, and has a second
Referring to the figure, an electromagnetic coil 24 is attached to a valve body 21 having a fuel inlet passage 22 and an outlet passage 23, and a valve body 26 for opening and closing the entrance of the outlet passage 23 is attached to the tip of a plunger 25 arranged at the center. It is installed. When the electromagnetic coil 24 is energized, the plunger 25 compresses the return spring 27 and the magnetic pole piece 2
8, the outlet path 23 is opened, and LP
The fuel in the G tank 2 flows from the inflow path 29 to the outflow path 32 via the filter 30, the inlet path 22, the valve chamber 31, and the outlet path 23, and is sent to the vaporizer 7, and the electromagnetic coil 2
4, the valve body 26 closes the outlet passage 23 by the spring force of the return spring 27 and cuts off the fuel, which is the same as a normal electromagnetic valve.

When the fuel flowing from the LPG tank 2 to the vaporizer 7 exceeds a certain flow rate, it is necessary to close the fuel passage 1 to ensure safety.

The present invention provides the emergency shutoff valve 4 with an overflow prevention function for this purpose. Therefore, means for measuring fuel flow;
A means for determining whether the measured flow rate is below or above a certain level, and a control means for closing the emergency shutoff valve 4 when the flow rate is above the certain level are required.

In this embodiment, the flow rate measuring device 35 is constituted by a differential pressure generator 36 consisting of an orifice installed upstream of the manual on-off valve 3 in the fuel passage 1, and a differential pressure detector 37 before and after the generator.
The flow rate determiner 38 was constituted by an electronic control device 39 consisting of a microcomputer installed in the automobile and into which the electric signal generated by the differential pressure detector 37 was input. Further, a controller 40 was configured by an electromagnetic relay 42 inserted into a conductive wire 41 to the electromagnetic coil 24.

When the fuel flow rate is below a certain level, the differential pressure across the orifice of the differential pressure generator 36 is below the set value, and the electronic control device 39 does not send a drive signal to the relay 42 .

When the fuel flow rate is above a certain level, the differential pressure across the orifice is above the set value, so the electronic control device 39 determines that the fuel passage 1 should be closed, and sends a drive signal to the relay 42 to open the contact and close the electromagnetic coil. 24 and closes the emergency shutoff valve 4.

When the fuel passage l is closed in this way, when the fuel on the downstream side of the emergency shutoff valve 4 is completely consumed, the engine 11
stops. At this time, when the key switch I2 is turned off, the drive signal is released and the contacts of the relay 42 are closed.

When the key switch 12 is turned on to restart the engine 11, the emergency shutoff valve 4 and the electromagnetic on-off valve 6 are both opened, and the overflow prevention function is canceled and automatically restored.

Alternatively, the key switch 12 may be left on and the drive signal may be released after a certain period of time to open the emergency shutoff valve 4.

When restarting, there is no fuel downstream of the emergency shut-off valve 4, so there is a risk that a large amount of fuel will flow all at once and the emergency shut-off valve 4 will be activated, so when the key switch 12 is turned on, the The electric signal from the flow rate measuring device 35 is canceled during the time period from start-up so that the drive signal is not sent to the relay 42 even if the differential pressure of the relay 42 is higher than the set value.

Also. The flow rate measuring device 35 may be of a water wheel type, a ball circulation type, etc. that directly detects the fuel flow rate.

[Effects of the Invention] According to the present invention, the fuel flow rate is measured and the emergency shutoff valve is closed when the flow rate exceeds a certain level, and the overflow prevention valve is eliminated and the emergency shutoff valve has an overflow prevention function. By canceling the drive signal, the system automatically returns to normal fuel supply and resumes normal fuel supply without having to manually return, which is extremely advantageous in terms of management and handling. Furthermore, it is easy to install in a narrow place such as the trunk of a car.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of a fuel supply device according to the present invention, FIG. 2 is a longitudinal sectional view showing an example of essential parts of the invention, and FIG. 3 is a system diagram of a conventional fuel supply device.

Claims (1)

[Claims] The fuel passage from the LPG tank to the vaporizer is equipped with a manual on-off valve, an emergency cut-off valve, and an electromagnetic on-off valve,
An emergency shutoff valve and an electromagnetic shutoff valve are used in a fuel supply system for an LPG engine that opens and closes simultaneously in conjunction with a key switch; a flow rate measuring device installed upstream of the emergency shutoff valve in the fuel passage; a flow rate determiner that determines whether the fuel flow rate is above or below a certain level based on an electric signal emitted by the device; and energizing the electromagnetic coil of the emergency cutoff valve by a drive signal that the flow rate judge generates when the fuel flow rate is above the certain level. A fuel supply device comprising: a controller that operates to shut off the fuel flow, and the fuel passage is not provided with an independent overflow prevention valve.