JP2719568B2 - Engine LPG supply device - Google Patents

Description

The present invention relates to an apparatus for pressurizing LPG with a fuel pump, injecting the LPG into an intake pipe from a fuel injection valve, and supplying the same to an engine. Used for LPG supply.

(Prior art) As a system for supplying LPG to a spark ignition type automobile engine, instead of using a vaporizer to decompress gasified LPG from a cylinder and sucking it into an intake air flow using a mixer, the fuel remains in a liquid state without gasification. It has been proposed to inject the intake air flow with an injection valve.

By the way, in an LPG supply device using a fuel injection valve, as disclosed in JP-A-59-82556 and JP-A-59-108855, when the internal pressure of the cylinder is set to the injection pressure almost as it is, thermal effects are caused. When gas is received, it is easily gasified, the pressure fluctuates extremely, and the metering by the fuel injection valve becomes extremely inaccurate. Therefore, Japanese Utility Model Application No. 60-21997 (Japanese Utility Model Application No.
Nos. 60-177417 (Japanese Utility Model Application Laid-Open No. 62-87162), JP-A-63-16160, JP-A-63-16161, and JP-A-63-16161.
Nos. 63-16162 and 63-18172, the LPG of the cylinder is further pressurized by a fuel pump to make it difficult to gasify, and then adjusted to a predetermined pressure by a pressure regulator to adjust the injection pressure. Is thought to be.

In such a system, surplus LPG released from the pressure regulator is returned to the cylinder, but if the fuel injection valve and the pressure regulator are installed separately, air bubbles may be generated in the supply pipe during engine stoppage. There is a disadvantage that the function of the fuel pump or the pressure regulator is accumulated and the function of the fuel pump or the pressure regulator is disturbed, and accurate injection from the fuel injection valve cannot be performed. Therefore, in an automobile, the fuel injection valve and pressure regulator are installed in a narrow engine room, and the excess LPG that passes through the return passage from the pressure regulator to the fuel pump inlet is heated by the engine heat, which causes thermal effects. When the engine is operated for a long time, the temperature of the LPG in the cylinder gradually rises due to the fact that the temperature of the LPG in the cylinder installed in the trunk room, which is difficult to receive, becomes higher and the LPG supply system is completely closed and the LPG circulates. It is dangerous because it rises and the vapor pressure gradually increases.

As a countermeasure, as disclosed in the microfilm of Japanese Utility Model Application No. 60-21997, returning excess LPG to the inlet side of the fuel pump without returning it to the cylinder has been considered. Since the LPG is pressurized by the fuel pump, the pressure is higher than the internal pressure of the cylinder.Therefore, only the excess LPG is supplied to the fuel pump and circulates. As a result, pressurization by the fuel pump becomes impossible and the amount of fuel injected from the fuel injection valve decreases, leading to a disadvantage that the engine stops.

On the other hand, as disclosed in the microfilm of Japanese Utility Model Application No. 60-177417, there is an improvement plan in which a cooling device is provided in a return passage of excess LPG from the pressure regulator to the fuel pump inlet side. When tested with a standard car engine of the order, a cooler with a cooling capacity of about 300-500 Kcal / h is required, and the extra LPG required by the engine to operate this cannot be ignored, and the fuel economy Not practical in terms of sex.

(Problems to be Solved by the Invention) According to the present invention, LPG of a cylinder is further pressurized by a fuel pump, adjusted to a predetermined pressure by a pressure regulator, injected from a fuel injection valve into an intake pipe, and excess LPG is returned to the cylinder. When the engine is operated for a long time,
It was made to solve the above-mentioned problem that there was no countermeasure that can prevent the temperature rise economically without impairing the normal fuel injection function, which is dangerous because the LPG temperature rises, It is an object of the present invention to provide an LPG supply device for an engine that does not raise the temperature without forcibly cooling excess LPG returned to the cylinder by a cooling device and maintains a normal fuel injection function.

(Means for Solving the Problems) To solve the problems with the LPG supply device of the engine, in which the LPG of the cylinder is pressurized by the fuel pump, adjusted to a predetermined pressure, injected from the fuel injection valve, and the excess LPG is returned to the cylinder. The measures taken by the present invention to accomplish this are as follows.

That is, a first pressure regulator installed near the cylinder and a second pressure regulator installed in the engine room, and a second pressure regulator separately provided with the two pressure regulators and connected to the cylinder. It has one return line and a second return line, and a first on-off valve and a second on-off valve provided respectively in the two return lines.

When the engine is started, the first on-off valve closes and the second on-off valve opens, and after a lapse of a certain time from the start, the first on-off valve opens and the second on-off valve opens. The valve closes.

(Operation) When the engine starts, the first on-off valve closes and the second on-off valve opens in the initial stage of operation, and the injection pressure of the LPG is adjusted by the second pressure regulator, and the excess LPG is fueled. Since the gas is returned to the cylinder from near the injection valve, the air bubbles accumulated in the supply pipe and the like are completely discharged. When a certain time has elapsed from the start, the first on-off valve opens and the second on-off valve closes, so that the injection pressure of the LPG is adjusted by the first pressure regulator, and the excess LPG is Circulates near the cylinder. Therefore, the complete liquid LPG without bubbles is sent to the fuel injection valve, and the temperature of the LPG in the cylinder does not rise because the excess LPG is not affected by the thermal effect of the engine.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings.

A fuel injection valve 4 is provided downstream of a throttle valve 3 of an intake pipe 2 including an intake manifold that distributes an air-fuel mixture to each combustion chamber of the engine 1.
The fuel injection valve 4 is provided from the liquid phase portion of the cylinder 5.
A filter 7, an electromagnetic shut-off valve 8, a fuel pump 9, and a fuel reservoir 10 are installed in order from the cylinder 5 side in a supply pipe 6 connected to the tank.

A first return line 11 is provided which branches off from a portion of the supply line 6 between the fuel pump 9 and the fuel reservoir 10 and is connected to the gas phase of the cylinder 5. 12 and an electromagnetic first on-off valve 13 are installed in order. This pressure regulator 12 is a well-known diaphragm-valve arrangement which operates according to the differential pressure between the outlet pressure and the inlet pressure introduced by the first conduit 14 from the outlet side thereof. The LPG sent to the fuel injection valve 4 is adjusted to an injection pressure of a predetermined pressure.

A second return line 15 connected to the inlet of the fuel injection valve 4 is provided, and a second pressure regulator 16 and a second electromagnetic on-off valve 17 are installed in this order. This pressure regulator 16 is also a well-known diaphragm-valve configuration that operates in response to the differential pressure between the outlet pressure and the inlet pressure introduced from the outlet side thereof by the second conduit 18. Adjusts the LPG sent from the fuel injection valve 4 to the injection pressure of a predetermined pressure, but a small-diameter bypass that always connects the inlet side and the outlet side.
19 is in parallel with the valve. Further, the opening degree sensor 21 of the throttle valve 3 and the suction negative pressure sensor 22
However, for example, a rotational speed sensor 23 is provided for a distributor of the engine 1, an oxygen sensor 24 is provided for an exhaust pipe 20, and a fuel reservoir is provided.
An LPG temperature sensor 25 and a pressure sensor 26 are respectively provided on the 10 and electric signals from these sensors 21... 26 are supplied to an A / D converter 28 and a central processing unit 2 mounted on an automobile.
9. LP which is inputted to the microcomputer 27 including the drive circuit 30 and has an appropriate flow rate according to the operation state of the engine 1
A drive current having a predetermined duty ratio is sent from the drive circuit 30 to the fuel injection valve 4 so that G is supplied.

In the device having such a configuration, the shut-off valve 8 and the two on-off valves 13 and 17 are closed when the engine 1 is stopped, and when the key switch is turned on, the shut-off valve 8 and the on-off valve
Simultaneously with the opening of the valve 17, the fuel pump 9 is driven, and the liquid LPG having a pressure flowing out of the cylinder 5 is further pressurized by the fuel pump 9 and is driven to open and close with a drive current having a duty ratio according to the operating state of the engine 1. From the fuel injection valve 4 to the intake pipe 2
Injected to. The LPG injected from the fuel injection valve 4 is injected into the intake pipe 2 at an injection pressure adjusted to a predetermined value by the second pressure regulator 16. The surplus LPG is returned to the cylinder 5 through the return line 15.

When the engine 1 starts operating, the second pressure regulator
16 has a bypass 19, so that the LPG passes from the inlet side to the outlet side until the set control pressure is reached, and is generated while the engine is stopped in the supply line 6, the return line 15, and the like. The accumulated air bubbles are quickly discharged into the cylinder 5 so that the pressurization by the fuel pump 9 and the pressure adjustment by the pressure regulator 16 can be performed smoothly and accurately, and when the air bubbles are completely discharged, the LPG becomes fuel. The pressure is increased by the pump 9 above the vapor pressure.

When a certain time has elapsed since the key switch was turned on, the LPG is supplied in a completely liquid state as described above.
And the fuel is injected into the fuel injection valve 4 at a pressure adjusted by the second pressure regulator 16. When such a state is reached, that is, when a certain period of time has elapsed since the engine 1 was started, the microcomputer 27
Or, the second return valve 15 is closed by closing the second on-off valve 17 based on a command of a timer (not shown) installed separately,
Instead, the first on-off valve 13 is opened to open the first return line 11. For this reason, after that, the first pressure regulator 12
Is adjusted to a predetermined injection pressure.

Here, the filter 7, the shut-off valve 8, the fuel pump 9, the first return line 11, its pressure regulator 12, and the on-off valve 13 are located in the trunk room indicated by the arrow AA, that is, outside the engine room and outside the cylinder. It is installed near 5. Also,
The fuel reservoir 10, the second pressure regulator 16 and the on-off valve 17 are installed in an engine room indicated by an arrow BB.

In the above configuration, the second pressure regulator 16 in the engine room controls the pressure of the LPG at the time of starting the engine 1. However, since the temperature in the engine room at the time of starting is close to the atmosphere except for special cases, The excess LPG returned to the cylinder 5 through the second return line 15 hardly rises in temperature, and is closed in a short time even at a high temperature.
G Does not raise temperature significantly. Further, since the excess LPG is returned to the cylinder 5 from a portion near the fuel injection valve 4, it is possible to exhaust the air bubbles accumulated in the supply pipe 6 and the like during the engine stop at the initial stage of the operation. Then, after a certain period of time has elapsed since the start of the engine 1, the first pressure regulator 12 installed near the cylinder 4 outside the engine room controls the pressure of the LPG. Since it is returned to the cylinder 5 and circulated in a place not affected by heat,
The LPG temperature of the cylinder 5 is not increased even if the operation is performed for a long time.

(Effect of the Invention) As can be understood from the above description, according to the present invention,
When the engine is started, the excess LPG is first returned to the cylinder via the second pressure regulator in the engine room, so that air bubbles in the supply pipe etc. are discharged and removed, and the function of the fuel pump and pressure regulator is smooth and accurate. The amount of fuel injected from the fuel injection valve is not disturbed. Also, after a certain time has passed, excess LPG is returned to the cylinder via the first pressure regulator near the cylinder without being thermally affected by the engine. High safety is obtained without increasing the LPG temperature in the cylinder without impairing the injection function or increasing the fuel consumption.

[Brief description of the drawings]

The drawings are layout diagrams showing an embodiment of the present invention. 1 ... engine, 2 ... intake path, 4 ... fuel injection valve, 5
... cylinder, 6 ... supply line, 9 ... fuel pump, 11 ...
... first return line, 12 ... first pressure regulator, 13 ... first on-off valve, 15 ... second return line, 16 ... second pressure regulator, 17 ... A second on-off valve,

Claims (1)

(57) [Claims] An LPG supply for an engine which pressurizes an LPG of a cylinder (5) with a fuel pump (9), adjusts the pressure to a predetermined pressure, injects the fuel from a fuel injection valve (4), and returns surplus LPG to the cylinder (5). In the apparatus, a first pressure regulator (12) installed near the cylinder (5) and a second pressure regulator (16) installed in an engine room, and the two pressure regulators (12). , 16) and the cylinder (5)
A first return line (11) and a second return line (15) connected to the first return line (11) and a first on-off valve (13) provided in each of the two return lines (11, 15); Second on-off valve (1
7), the first on-off valve (13) is closed when the engine is started, and the second on-off valve (17) is opened. An LPG supply device, wherein the on-off valve (13) is opened and the second on-off valve (17) is closed.