JP2002070652A - Pressure regulator in liquefied gas feeding device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate trouble causing the starting fault or operation failure of an engine by injecting an unvaporized liquefied gas along with a vaporized gas at low temperatures when injecting high pressure a liquefied gas from a fuel injecting valve by adjusting the pressure thereof to a predetermined normal pressure. SOLUTION: The liquefied gas in a cylinder 1 is heated by an engine cooling water in a preheating chamber 15 to vaporize it is fed into a pressure regulating chamber 18 through an entrance valve 24 to adjust its pressure to the predetermined normal pressure and fed to a fuel injection valve 5 from a communication chamber 29 through a separation chamber 28. When the liquefied gas is fed along with the vaporized gas by opening the communication passage 29 to form an opening 29C at the lower position of the separation chamber 28, the liquefied gas having high specific gravity is accumulated at the bottom part as it is, and only the liquefied gas having low specific gravity is fed from a fuel exit 30 located at a high position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for adjusting a liquefied gas, generally a liquefied petroleum gas, to a predetermined positive pressure to be supplied to an engine as fuel by injecting the gas into an intake pipe.

[0002]

2. Description of the Related Art The use of liquefied petroleum gas as fuel for a spark ignition engine has been widely known, and in commercial vehicles, high-pressure liquid liquefied petroleum gas filled in a cylinder is called a regulator or a vaporizer. Supply to the engine by a system that adjusts the vaporized gas to about atmospheric pressure with a pressure regulator, sucks it with the venturi negative pressure of the mixer installed in the intake pipe, and mixes it with the intake air Is well known.

In many mixers, the venturi diameter is adapted to the low / medium speed range of the engine, and idle adjustment means, high output means, air-fuel ratio control means, and the like are provided, so that the mixture can be properly adjusted over the entire operation range of the engine. In order to supply a quantity of fuel and comply with emission regulations, not only is the configuration significantly complicated, but also the control system of each means is complicated.

As a solution to this problem, liquefied petroleum gas is sent to a fuel injection valve installed in an intake pipe by using a saturated vapor pressure in a cylinder or pressurized by a pump and injected in a liquid state. It is proposed in Japanese Utility Model Laid-Open No. 59-43659 or Japanese Utility Model Laid-Open No. 62-87162. Further, since liquid liquefied petroleum gas is easily affected by temperature and is unstable, it is adjusted to a gas of a predetermined positive pressure and sent to a fuel injection valve to inject the vaporized gas.
No. 09 publication.

[0005]

When injecting a liquefied gas into an intake pipe and supplying it to an engine, the mainstream idea is to use a method in which a liquefied gas is not liquid at present but is adjusted to a predetermined positive pressure and injected. In order to convert the high-pressure liquid liquefied gas of the cylinder into a predetermined positive pressure vaporized gas, for example, a two-stage pressure reducing type pressure regulator as described in Japanese Patent Application Laid-Open No. 11-514460 is used. Can be

[0006] The pressure regulator is generally used as a heat source for changing the engine cooling water from a liquid to a gas, but when the temperature of the cooling water is low, such as when starting the engine, sufficient heat exchange is not performed. In addition, since the degree of vaporization due to the reduced pressure is small in the pressure regulator that generally adjusts the injection pressure to about 30 KPa, the ratio of the liquefied gas that is not vaporized increases.

[0007] When the vaporized gas whose pressure is adjusted while containing the liquefied gas in a liquid state is injected from the fuel injection valve into the intake pipe, not only the air-fuel ratio is degraded, but also the engine is poorly started due to the rich mixture. In addition, there is a concern that a malfunction such as a driving malfunction or a stop may occur.

According to the present invention, there is provided a pressure regulator for adjusting a high-pressure liquid liquefied gas filled in a cylinder to a predetermined positive pressure and sending it to a fuel injection valve provided in an intake pipe. In order to solve the above-mentioned problem, complete vaporization cannot be performed when the pressure is low, and there is a concern that unvaporized liquefied gas is sent to the fuel injection valve together with the vaporized gas to cause an inconvenience due to rich mixture. Even when the engine coolant temperature is low, only a predetermined positive pressure vaporized gas is sent to the fuel injection valve to supply an air-fuel mixture with a required air-fuel ratio to the engine, thereby ensuring reliable starting and stable operation. It is an object of the present invention to provide a pressure regulator which can be adjusted.

[0009]

In order to solve the above problems, the present invention provides a preheating chamber having a fuel inlet connected to a cylinder for heating and vaporizing introduced liquefied gas with engine cooling water, A pressure control chamber that opens and closes the preheating chamber by an inlet valve that operates to open when the pressure is lower than the set pressure and closes when the pressure is higher than the set pressure, and has a fuel outlet connected to the fuel injection valve at a high position And a separation chamber in which a communication passage extending from the pressure adjustment chamber is opened at a low place.

The high-pressure liquid liquefied gas is heated in the preheating chamber to become a vaporized gas, and the vaporized gas entering the pressure regulating chamber through the inlet valve is maintained at a predetermined positive pressure by opening and closing the inlet valve.
This vaporized gas is sent from the communication passage through the separation chamber to the fuel injection valve from the fuel outlet. When the temperature of the engine cooling water is low, liquefied gas that is not vaporized in the preheating chamber enters the pressure adjustment chamber, and vaporization is performed by the reduced pressure at that time.If unvaporized liquefied gas remains at this stage, this will occur. When entering the separation chamber, it accumulates at a low place, and only the vaporized gas is sent to the fuel injection valve from the fuel outlet at a high place.

In practicing the present invention, the preheating chamber, the pressure adjustment chamber and the separation chamber are formed in a vertically long shape, the fuel inlet is provided at a low place of the preheating chamber, and the inlet valve is provided at the height of the preheating chamber and the pressure adjustment chamber. And a communication passage which is opened at a place not adjacent to the inlet valve of the pressure control chamber, extends upward from it, and then reverses downward to open at the lowest part of the separation chamber. Is preferred.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. An electromagnetically driven shut-off valve 2 extending from a liquid phase portion of a cylinder 1 filled with a liquefied gas, generally a liquefied petroleum gas.
Liquefied gas passage 3 provided with fuel inlet 1 of pressure regulator 10
7 is connected. The vaporized gas adjusted to a predetermined positive pressure by the pressure regulator 10 is sent to the fuel injection valve 5 through the vaporized gas passage 4 connected to the fuel outlet 30, injected into the intake pipe 6 and supplied to the engine 7. . The shutoff valve 2 and the fuel injection valve 5 are electronically controlled based on the air flow rate in the intake pipe 6, the throttle valve position, the cooling water temperature of the engine 7, the crank angle, the oxygen concentration in the exhaust gas, and the like. The above is a general fuel supply system which is no different from the conventional one.

The pressure regulator 10 includes a first main body 11 and a second main body 13 which are overlapped with each other back to back, and a first cover body 12 and a second cover body 14 which cover end faces opposite to the superposed surface. Which are secured to each other by bolts or screws.

The first main body 11 has a vertically long preheating chamber 15 and a pressure adjusting chamber 18 arranged side by side. The preheating chamber 15 has a bottom cover body closed to the first main body 11 with its lower end open surface closed. A fuel inlet 17 provided at 16 is open. The diaphragm 1 in which the depression opened to the end face is fixed to the first main body 11 and the first cover body 12 by sandwiching the peripheral edge thereof is formed in the pressure adjustment chamber 18.
9 is formed so as to be shielded.

An adjusting spring 21 composed of a compression coil spring inserted between the diaphragm 19 and an adjusting nut 20 screwed to the first cover body 12 acts on the center of the diaphragm 19. Pressure adjustment chamber 18
Can be adjusted. The pressure adjustment chamber 18 has a built-in valve lever 23 rotatably supported by a support shaft 22. A valve body 25 of an inlet valve 24 is attached to one end of the pressure adjustment chamber 18, and the other end of the diaphragm 19 is The central part is engaged. The inlet valve 24 includes the preheating chamber 15 and the pressure regulating chamber 1
8 are connected to each other at their highest part.
7 is constituted by the valve seat 26 provided on the valve 7 and the valve element 25 described above.

When the diaphragm 19 is displaced toward the pressure adjusting chamber 18, the valve body 25 is separated from the valve seat 26 in accordance with the rotation of the valve lever 23, and when the diaphragm 19 is displaced in the opposite direction, the valve body 25 is displaced from the valve seat 2.
Sit at 6. That is, when the pressure in the pressure adjusting chamber 18 becomes lower than the pressure set by the adjusting spring 21, the inlet valve 24
Is opened to communicate the preheating chamber 15 with the pressure adjustment chamber 18, and when the pressure rises, the inlet valve 24 closes to shut off the preheating chamber 15 and the pressure adjustment chamber 18, so that the inside of the pressure adjustment chamber 18 is closed. Maintain a predetermined set pressure.

The second main body 13 has a separation chamber 28 formed on the end face on the side opposite to the first main body 11 by blocking the open dent with the second cover body 14. This separation chamber 28 is also vertically long, and has a fuel outlet 30 at its upper end.

The pressure control chamber 18 and the separation chamber 28 are connected to each other by the communication passage 2.
9 are always in communication with each other. The communication passage 29 is located at a position not adjacent to the inlet valve 24, preferably at a position near the bottom with respect to the inlet valve 24 provided at a high position.
Opening 29 _A to 8, extends upward far from reaching the inside of the first main body 11 near the top, then the interior of the tube passage 29 _B that is incorporated drooping in the longitudinal direction of the separation chamber 27 of the second body 13 It is connected to extend to the upper end in the transverse direction and is open 29 _C in the lowest portion of the separation chamber 28 at the lower end of the tube passage 29 _B.

On the other hand, a cooling water passage 31 for circulating the cooling water of the engine 7 is provided in the first main body 11 and the second main body 13. The cooling water passage 31 is formed so as to mainly heat the preheating chamber 15.
8 is preferably arranged so that it can be heated well.

The high-pressure liquid liquefied gas in the cylinder 1 passes through the liquefied gas passage 3 and enters the separation chamber 15 from the fuel inlet 17 and is heated by the engine cooling water to become a vaporized gas. When the pressure in the pressure adjustment chamber 18 becomes lower than the set pressure, the inlet valve 24 opens, and the vaporized gas in the separation chamber 15 flows into the pressure adjustment chamber 18 through the passage 27, and when the pressure becomes higher than the set pressure, the inlet valve becomes open. The valve 24 is closed to stop the flow of the vaporized gas. As a result, the vaporized gas whose pressure has been adjusted to a predetermined positive pressure is supplied to the communication passage 2.
9, the gas enters the separation chamber 28, and is sent from the fuel outlet 30 to the fuel injection valve 5 through the vaporized gas passage 4.

When the warming-up of the engine 7 is not completed and the temperature of the engine cooling water is low, sufficient heat exchange cannot be performed in the preheating chamber 15, and the vaporized gas accumulated in the upper part is transferred to the pressure adjusting chamber 18. The liquefied gas which remains liquid when flowing in also passes through the inlet valve 24. When the high-pressure liquefied gas flows into the pressure adjustment chamber 18 having a lower pressure, it is vaporized by decompression. However, since the pressure adjustment chamber 18 has a pressure of about 30 KPa, it is difficult to completely vaporize the liquefied gas. In many cases, it is unavoidable to flow into the pressure adjusting chamber 18 together with the vaporized gas as it is.

[0022] provided at a lower point near the bottom without adjacent opening 29 _A into the pressure control chamber 18 of the communication passage 29 to the inlet valve 24 in the present embodiment, flows with ejection state from the inlet valve 24 by a pressure difference Even if the liquefied gas is scattered, the communication path 29
And it is difficult to enter directly. Therefore, only the vaporized gas out of the vaporized gas and the liquefied gas flowing into the pressure adjusting chamber 18 enters the communication passage 29 and is sent to the separation chamber 28. Also,
Even if the liquefied gas enters the communication passage 29, in the present embodiment, the communication passage 29 is formed so as to extend upward, so that it is difficult to be entrained. It evaporates with the rise.

When the temperature of the engine cooling water is extremely low,
A large amount of unvaporized liquefied gas flows into the pressure adjustment chamber 18 together with the vaporized gas, so that it is inevitable that the vaporized gas and the liquefied gas may be sent to the separation chamber 28. In such a case, the communication passage 29 is provided at the lower part of the separation chamber 28 with an opening 29.
Since the _C liquefied gas heavy specific gravity reservoir as it bottoms when entering, and only the vaporized gas of light specific gravity is sent from the high place of the fuel outlet 30. The liquefied gas collected at the bottom of the separation chamber 28 evaporates with the temperature of the engine cooling water.
Since the pressure in the separation chamber 28 and the pressure adjustment chamber 18 communicating with the separation chamber 28 through the communication passage 29 increases with vaporization,
Until the vaporized gas is injected from the fuel injection valve 5 and returns to the set pressure, the inlet valve 24 keeps the valve closed.

[0024]

As described above, according to the present invention, even in a situation where the temperature of the engine cooling water is too low to completely vaporize, the unvaporized liquefied gas can be properly separated to remove only the vaporized gas. The fuel is sent to the fuel injection valve to make the engine surely start and operate stably.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 cylinder, 5 fuel injection valve, 6 intake line, 7
Engine, 10 pressure regulator, 15 preheating chamber, 1
7 fuel inlet, 18 pressure regulating chamber, 24 inlet valve,
28 separation chamber, 29 communication passage, 30 fuel outlet,
31 cooling water passage,

Claims (2)

[Claims] When injecting a high-pressure liquid liquefied gas filled in a cylinder from a fuel injection valve provided in an intake pipe, the liquid liquefied gas is adjusted to a predetermined positive pressure vaporized gas and is supplied to the fuel injection valve. A pressure regulator in a liquefied gas supply device of an engine to be fed, which has a fuel inlet connected to a cylinder and heats and vaporizes the introduced liquefied gas with engine cooling water, and a preheating chamber.
A pressure regulating chamber which is opened / closed to the preheating chamber by an inlet valve which operates to open when the internal pressure is lower than the set pressure and closes when the internal pressure is higher than the set pressure, and a fuel outlet connected to the fuel injection valve to a high level. And a separation chamber having a communication passage extending from the pressure adjustment chamber at a low position. 2. The preheating chamber, the pressure adjustment chamber, and the separation chamber are formed in a vertically long shape, the fuel inlet is provided at a low position of the preheating chamber, and the inlet valve is provided between the preheating chamber and the pressure adjustment chamber. The communication passage is provided at a location not adjacent to the inlet valve of the pressure regulating chamber and extends upward therefrom and then reverses and extends downward, and is provided at the lowest point of the separation chamber. 2. The pressure regulator according to claim 1, wherein the pressure regulator is open at a site.