JPS60222550A - Fuel feeding device for lpg internal-combustion engine - Google Patents

Abstract

PURPOSE:To carry out the removal of foam on starting and stabilize control by providing a throttle in parallel with a fuel pressure regulator in a fuel return passage of a device for injecting an LPG liquid by pressure. CONSTITUTION:When solenoid valves 2, 19 are opened and a pump 6 is driven on starting an engine, a liquid in an LPG tank 1 is fed to an injection valve 10 through a fuel pressure requlator 3 and a fuel sump 7. The fuel pressure and temperature are detected 8, 9 in the fuel sump 7, and the detected values are fed, together with other detected values of an engine operating condition, into a control unit, whose output makes the injection valve 10 open and close to inject a defined quantity of fuel. The fuel pressure regulator 3 is provided in a fuel return passage 14, to regulate a return fuel pressure by opening and closing its valve 21 in accordance with a spring 20 and feeding fuel pressure. A throttle 17 is provided in parallel with the valve 21, which enables foam in a pipe to be returned to the tank 1 regardless of the operation of the valve 21, at the time of starting and, therefore, only a small quantity of fuel, except the return fuel through the throttle 17, is required to be regulated by means of the valve 21 at the time of normal operation, thereby stabilizing control.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a fuel supply system for a liquefied petroleum gas (hereinafter referred to as LPG) internal combustion engine, and particularly for an LPG internal combustion engine that measures and injects fuel in liquid form. Regarding a fuel supply device.

[Background of the invention]

The saturated vapor pressure of LPG used as fuel for automobile internal combustion engines varies from 0 to 20% depending on the fuel composition and ambient temperature.
Kf/cr711 usually varies greatly from 2 to 7 to 9/Cd. 7' (L) is stored in cylinders as automobile fuel.
P and G can be pumped at the saturated vapor pressure. For this reason, conventional fuel supply systems equipped with vaporizer mixers do not require a fuel pump. However, in a fuel supply device that includes a fuel injection valve and controls the amount of liquid LPG fuel supplied to the internal combustion engine based on the valve opening time, air bubbles may be mixed in the liquid fuel supplied to the injection valve. It is impossible to accurately measure the amount of fuel supplied. In order to solve this problem, the applicant installed a fuel pump between the fuel cylinder and the injection valve, and
The patent application proposes a system in which the fuel is pressurized and supplied to the injection valve, and a restriction is provided in the return passage leading from the injection valve to the fuel cylinder, thereby suppressing the generation of air bubbles and allowing accurate fuel metering. 58-173058.

Since a rotary pump such as a roller vane pump is generally used as the fuel pump of the fuel supply device, the pressurized fuel pressure pulsates. In addition, the presence or absence of bubbles or the amount of bubbles generated in LPG varies greatly depending on the temperature conditions of the piping and cylinder, and since these bubbles are supplied to the fuel pump, the pressurizing pressure varies greatly with the pulsation even in the same pump. do. According to the applicant's experiments, even if the fuel pressure after pressurization by the fuel pump is the same, when the fuel pressure before pressurization is different, that is, when the pressurization force by the fuel pump is different, the opening time of the fuel injection valve is The results show that even though the fuel injection amounts are the same, the fuel injection amounts are significantly different. Therefore, there was a problem in that it became impossible to correct the fuel injection amount based on the fuel pressure.

The applicant also measures the fuel pressure and fuel temperature, calculates the fuel composition and liquid ratio type, and adjusts the opening time of the fuel injector according to the fuel pressure, fuel composition, and liquid ratio type. The system was proposed in Utility Model Application No. 57-138954.

The proposed fuel supply system uses a pump to pressurize fuel and supplies it to the injection valve, so it is necessary to measure the fuel pressure before pressurization by the pump in order to calculate the fuel composition and liquid ratio type. However, there is a drawback that two fuel pressure sensors are required, one for measuring the fuel pressure after pressurization as the fuel pressure applied during injection valve operation.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and its purpose is to maintain a constant pressurizing force of a fuel pump installed in a fuel supply system of an LPG internal combustion engine, and to achieve a stable mixture ratio. An object of the present invention is to provide a fuel supply device for an LPG internal combustion engine with a simple structure capable of controlling the supply of fuel mixture.

[Summary of the invention]

The present invention is achieved by arranging in parallel a regulator that controls the pressurizing force by the throttle and the fuel pump in the fuel return passage that returns fuel from the fuel injection valve of the fuel supply system of the LPG internal combustion engine to the gas phase side of the fuel cylinder. , which was designed to achieve the intended purpose.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel supply system for an LPG internal combustion engine according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

In the figure, LPG fuel is supplied from the liquid phase side of a fuel cylinder 1 to a fuel pump 6 through a solenoid pulp 2, a low pressure side lower chamber 5 separated by a diaphragm 4 provided in a regulator 3. This fuel pump 6
After being pressurized by the pressurizer, it is sent to the fuel reservoir 7, where the fuel pressure after pressurization and the fuel temperature are measured by temperature sensors such as fuel pressure min. is supplied to valve 10. By opening this fuel injection valve 1°, a portion of the LPG fuel enters the throttle chamber 1.
1, and is supplied to the engine 13 through the mosquito entry pipe 12. Fuel not injected from the injection valve 1o passes through a return passage 14 and is supplied to a high-pressure side upper chamber 15 that is engaged with the diaphragm 4 of the regulator 3, and a regulator passage 16 that is integrated into the regulator 3. The fuel passes through a throttle 17 parallel to the above, passes through a solenoid pulp 19, and returns to the gas phase side of the fuel cylinder 1. Lower chamber 5 on the low pressure side of the regulator 3
A regulator spring 2o that controls the pressurizing force of the fuel pump 6 is attached to the diaphragm 4.
The pressure applied to the high pressure side upper chamber 15 and the upper part of the diaphragm 4 is applied to the regulator spring 2.
When the sum of the elastic force of .degree. Return to the gas phase side of the fuel cylinder 1. The spring load of the regulator spring 2o is set to be smaller than the pressurizing force of the fuel pump when the escape amount is only the throttle shear. It is configured to be pressurized.

In one embodiment of the present invention configured as described above, the restrictor 17 has the function of returning air bubbles to the cylinder 1 when LPG fuel is not yet in the pressurized passage near the fuel injection valve, such as when starting the engine. have When the key is turned on at startup, solenoid valves 2 and 19 open, and the fuel pump 6 is driven to pressurize the LPG fuel, but it is throttled! 1) 17
If there is no air bubbles in the pipe 4, there is no place for them to escape, and there are also air bubbles on the inlet side of the fuel pump 6, which reduces the efficiency of the fuel pump, and the air bubbles in the fuel passage cannot escape due to insufficient pressurization. Unable to start and accurately control metering. By providing a throttle valve, air bubbles in the fuel passage are released for a short period of time just before starting, and the efficiency of the fuel pump 6 remains almost constant.The efficiency of the fuel pump 6 remains constant due to the sufficient pressurization and balance with the regulator spring 20. The pressure is regulated to the applied pressure. Also aperture 1
If there is only 7 and no regulator 3, the pressurizing force of the pump will be 4 Ky/mm2 due to air bubbles on the fuel pump inlet side.
In this case, a large pressure difference occurs in the range of 1 to 4 kg/van. This is mainly due to irregular air bubbles generated when passing through the solenoid valve 2 in front of the fuel pump 6.
c; hru. The LPG fuel is warmed up during passage by the heat generated by the fuel pump 2, and a portion of the fuel enters the gas phase side of the vapor pressure diagram (not shown) and generates bubbles. For this reason, the regulator 3 is required to keep the pressurizing force completely constant.

As mentioned above, M? 17 mainly has the function of releasing air bubbles when starting the engine, and by selecting an appropriate gas orifice diameter, the pressure regulating effect of the synculator 3 can be made more precise.
Compared to the case where only the regulator 3 is used, there is less fuel pressure pulsation and it also serves as a damper, and it is also possible to remove the damper from the system.

〔Effect of the invention〕

As described above, according to the present invention, the fuel supply system for an LPG internal combustion engine is provided with a simple regulator and a throttle in parallel, so that the pressure of the fuel pump can be kept constant at all times. l Eliminates the influence of changes in fuel-fuel ratio due to pressure fluctuations,
By measuring the pressure after pressurization with one fuel pressure sensor, various controls can be performed accurately, and furthermore, the pulsation of the fuel pump can be absorbed, which is very effective.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the configuration of an embodiment of a fuel supply system for an LPG internal combustion engine according to the present invention, and FIG. 2 is a longitudinal cross-sectional view showing details of the regulator section of FIG. 1. 1...Fuel cylinder, 2.19...Solenoid valve 3...Regulator, 4...Diaphragm, 6...
・Fuel pump, 8...Fuel pressure sensor, 9...m&
Sensor, 13... Engine, 14... Fuel return passage, 16... Regulator passage, 17... Throttle
t S-, regulator seat, 2o... Lugure~tasfring, 21... regulator valve. Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. A fuel cylinder that stores liquefied petroleum gas, a fuel injection valve that controls the amount of liquefied petroleum gas supplied to the internal combustion engine by the valve opening time, and a connection between the fuel injection valve and the liquid phase outlet of the fuel cylinder. In the fuel supply device for a liquefied petroleum gas internal combustion engine, the fuel pump is provided between the fuel pump and the fuel return passage for returning fuel from the fuel injection valve to the gas phase side of the fuel cylinder. 1. A fuel supply device for a liquefied petroleum gas internal combustion engine, characterized in that a regulator and a regulator for controlling the pressurizing force of the fuel pump are provided in parallel.