JPS63289250A - Fuel supply device for liquified petroleum gas internal combustion engine - Google Patents

Abstract

PURPOSE:To enable delicate flow control to be carried out by constituting so that the negative pressure regulated in the bypass passage around a throttle valve is introduced into the upper chamber, partitioned by a diaphragm, of a regulator in which liquified petroleum fuel is vaporized to carry out pressure regulation. CONSTITUTION:Liquid LPG is supplied from a fuel bomb 1 through a solenoid valve 2 to a regulator 3, and is heated and vaporized by a hot water being flowed through thereinto from a radiator, and is regulated to a prescribed pressure. The LPG fuel regulated in pressure enters a fuel measuring part 4 to be measured, and then is discharged into an intake pipe 9. In this case, a bypass passage bypassing a throttle valve 8 is provided, and on the way thereof an orifice 14 is interposed, and further in parallel with this orifice 14 an air control valve 25 is connected. Furthermore, even on the upstream side, further, than the connecting part of the bypass passage for the air control valve 25, an orifice 15 is interposed, and a composite negative pressure passage 16 branched from the downstream side of this orifice 15 is connected to the upper chamber of the regulator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a fuel supply system for a liquefied petroleum gas internal combustion engine used in automobiles, working machines, and the like.

BACKGROUND OF THE INVENTION A conventional fuel supply system for liquefied petroleum gas (hereinafter referred to as LPG) consists of a vaporizer and a mixer. This is a method of controlling pressure-regulated fuel. In this method, the venturi negative pressure generated is small in a small air flow area such as in a fitting ring, so fuel injection becomes unstable. As a countermeasure to this, the diameter of the venturi is made smaller to increase the negative pressure of the venturi and stabilize the injection of fuel. However, reducing the diameter of the venturi has the disadvantage that in the fully open high speed range, which requires a large air flow rate, this becomes a resistance and the output is sacrificed.

In addition, similar to the through system of a gasoline vaporizer, the small flow rate range of fuel can be controlled by 0.3
There is a method of injecting fuel whose pressure is regulated by Kp/cd into this small flow rate region and selecting the pentier diameter at a large air flow rate of maximum output, but it is difficult to eject fuel from the fuel nozzle using a slow system and venturi negative pressure. In the beginning,
Smooth air-fuel ratio control is difficult. Therefore, when selecting the diameter of the venturi, there was a drawback that a compromise had to be made in consideration of this fuel connection.

On the other hand, as in JP-A-59-192856, LPG in the primary chamber of the vaporizer is vaporized and pressure regulated to 0.31'P/
There is a system that aims to improve output by injecting LPG directly upstream of the throttle valve and removing the venturi.

The fuel meter for this system uses a linear step actuator, firstly the first needle and second needle are arranged coaxially, and the fuel flow rate is continuously measured while covering the entire fuel flow rate from small flow to large flow. It's in control. However, this fuel flow rate control method has a problem with followability during acceleration, and requires a separate injection system for acceleration correction. Additionally, there is a problem in followability during sudden deceleration, and there is a drawback that a complicated system such as a fuel cut must be installed.

Furthermore, instead of the linear step 7 cutuator described above, it is possible to use a duty-controlled lenoid valve. Current duty solenoid valves have a narrow flow rate control range, and there are no valves that can control from small to large flow rates.

Further, the flow rate accuracy is approximately 10%, which is inappropriate for control. To explain this using concrete numbers, 2000
ω Engine's required fuel flow width is 0.3 LPG injection pressure.
Kg/cd, from idle to full throttle high speed is approximately 2.
5 t7rritt to 210t/NR. The accuracy of this flow rate range is ±3%, and the idling edge is ±0.0.
75 L/mix is required. On the other hand, in the current duty solenoid valve, the duty range of 20 to 80% is the proportional control range of the flow rate. Therefore, the maximum flow rate is 2
If it is 10t/m, the minimum flow rate will be 10t/m or more,
The required minimum flow rate of z51/mix becomes uncontrollable. Even if future improvements make it possible to control the minimum flow rate, control of the dewatering width of 1% would be 3°5t/mls (=21
0/60), and in order to guarantee a flow rate accuracy of ±0.075t/home, the pulse width accuracy must be ±0.021%. Since the current control frequency is around 150Hz, the pulse width is 6.67m5 and the resolution is 1.4μs.
(6,67X0.0IXO,021), which is about 0.7
MHz control. Since the microcomputer clock is IMHz, it is practically uncontrollable.

Problems to be Solved by the Invention The present invention solves the above-mentioned problems, and enables precise flow control over the entire fuel flow range including acceleration/deceleration with one duty solenoid pulp, and a simple method that does not have a venturi. The system seeks to improve output and accuracy.

Means for solving the problem (1) An orifice 14 is provided on the downstream side of the throttle valve of the throttle chamber 7, and this orifice 14 and l1
lJK air control valve 25 is provided. Throttle valve 8
An orifice 15 is also provided on the upstream side of the orifice 15, and the negative pressure generated in these orifices 14 and 15 is applied to the regulator upper chamber 23 through the combined negative pressure passage 16 to control the LPG pressure in the regulator 3 and the fuel flow rate. That is.

(2) A pressure sensor 27 and an orifice 14 are provided on the downstream side of the throttle valve of the throttle chamber 7, and a duty solenoid valve 28 is provided on the upstream side of the throttle valve. The negative pressure regulated by the orifice 14 and the duty solenoid valve 28 passes through the synthetic negative pressure passage 16 to the regulator upper chamber 2.
31C and controls the LPG pressure of the regulator 3 to control the fuel flow rate.

The present invention is a fuel supply device for a liquefied petroleum gas internal combustion engine having the above configuration.

Operation The present invention controls the LPG pressure in the regulator lower control chamber 20 in relation to the suction pipe negative pressure by controlling the pressure in the regulator upper chamber 23, thereby controlling the fuel pressure applied to the duty solenoid valve 5 for metering fuel. change it,
This aims to expand the control range of fuel flow rate and perform fine flow control.

Embodiment This invention will be explained with reference to the drawings. In FIG. 1,
Liquid LPG is supplied from a fuel pump 1 to a regulator 3 through an LPG solenoid valve 2. In the regulator sectional view of FIG. 2, LPG fuel enters the lower control chamber 20 from the regulator port 17 through the gap between the sheet 19 and the pulp 18 and is vaporized. At this time, in order to prevent the regulator 3 from freezing due to latent heat of vaporization, a hot water passage 24 through which hot water from the radiator passes is provided in the lower control chamber 20. The regulator 3 is divided into upper and lower chambers by a diaphragm 21 in order to pressurize the vaporized LPG to a specified pressure.The upper chamber 23 is provided with a diaphragm spring 22 to regulate the LPG pressure when the throttle valve is fully opened. On the other hand, the suction pipe negative pressure on the downstream side of the throttle valve passes through the orifice 14, is reduced in pressure by air entering from the orifice 15 on the upstream side of the throttle valve, and is led to the regulator upper chamber 23 through the synthetic negative pressure passage 16. There is. The LPG fuel is pressurized to a predetermined pressure by this negative pressure and the load of the diaphragm spring 22.

This pressure-controlled LPG fuel enters the fuel metering section 4,
It is metered by the duty solenoid valve 5, injected to the upstream side of the throttle valve of the throttle chamber 7, and supplied to the engine through the intake pipe 9. Next, a method of measuring the fuel flow rate will be explained.

The air flow rate signal measured by the air flow meter 0 or the like is input to the controller 6, and the basic fuel flow rate is determined. In addition, in order to detect the composition of LPG, the temperature and pressure of liquid LPG are detected by a temperature sensor 10 and a pressure sensor 11 attached to the LPG solenoid valve 2.
It is input to the controller 6. Then, the LPG composition is determined, the temperature of the gas is detected by the temperature sensor 12, and the LPG composition is determined.
The specific weight of the G composition in the vaporized state is calculated, and a correction value is given for comparison with the specific weight in the standard state. In addition, K, engine cooling water temperature correction to detect engine warm-up state, and 0
Air-fuel ratio correction etc. are provided by two sensors, and the required fuel flow rate of the engine is calculated.

Then, the pressure sensor 13 detects the fuel pressure in the regulator lower control chamber 20, calculates the pressure correction coefficient, outputs a duty signal for the required fuel flow rate from the controller 6, operates the duty solenoid valve 5, and controls the required fuel flow rate. is supplied to the engine. In addition, in response to sudden changes in suction pipe negative pressure during deceleration, air is taken in from the air intake port 26 by the air control valve 25, which starts opening at a certain point on the higher negative pressure side than idling, and the negative pressure applied to the regulator upper chamber 23K is The pressure is being reduced. This is illustrated in FIGS. 3 and 4. FIG. 3 shows the pressure in the regulator upper chamber 23 relative to the suction pipe negative pressure, which is determined by selecting the diameters of the orifices 14 and 15.

The bending at high negative pressure of -500 mHg or more is due to the diameter of the air intake port 26 when the air control valve 25 opens. FIG. 4 shows the pressure in the lower control chamber 20 with respect to the suction pipe negative pressure, and shows the fuel pressure relationship in the lower control chamber 20 when the pressure in the upper chamber 23 is set as shown in FIG. In this way, the fuel pressure is increased as the load changes from light to high, and the fuel pressure applied to the fuel metering section 4 is varied, thereby extending the period during which the fuel flow rate is controlled.

FIG. 5 shows another embodiment in which a suction pipe negative pressure sensor 27 is provided on the downstream side of the throttle valve and a duty solenoid valve 28 is provided on the upstream side of the throttle valve in place of the orifice 15 and air control valve 25 shown in FIG. This shows the regulator lower control chamber 2 for the suction pipe negative pressure shown in Figure 4.
0 pressure is input into the memory of the controller 6 as a reference pressure. When the suction pipe negative pressure sensor 27 detects the suction pipe negative pressure, the reference pressure of the p-ler memory is calculated and detected by the pressure sensor 13. In order to make the pressure in the lower control chamber 20 equal to this reference pressure, the duty solenoid valve 28 is turned ON-O by the controller signal.
The negative pressure applied to the regulator upper chamber 23 is controlled by introducing air by turning it FF. This is shown in a chart as shown in Fig. 6.

In this system, the same control can be obtained even if the duty solenoid valve 28 is used as an orifice and the orifice 14 is replaced with a duty valve/id valve.

In addition, by replacing the suction pipe negative pressure sensor 27, by using an air flow sensor and an engine rotation sensor, or by using a throttle valve opening sensor and an engine rotation sensor, the standard pressure of the regulator lower control chamber 2o is created. It is also possible to control the pressure in the lower control chamber 20.

The throttle 29 in the synthetic negative pressure passage 16 shown in FIG. 1 is provided to prevent pressure fluctuations in the regulator upper chamber 23.

Effects of the Invention The present invention does not require a pentier and uses a duty solenoid valve to control fuel.

The heat flow range required by the engine can be controlled accurately (sufficiently), and output can be improved.Also, since the structure is simple, it can be handled by making slight changes to conventional equipment. .

Even in response to sudden changes in suction pipe negative pressure during acceleration and deceleration, the fuel flow 1 is controlled by the pressure response of the regulator lower control chamber 20.
can be controlled quickly, making the car more responsive.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the present invention, Fig. 2 is a cross-sectional view of the regierator of the present invention, Fig. 3 is a relationship between the pressure in the upper chamber of the regulator and the negative pressure in the suction pipe, and Fig. 4 is a diagram showing the negative pressure in the suction pipe. FIG. 5 is a partially cutaway system diagram showing another embodiment of the present invention, and FIG.
The figure is a chart of other embodiments (5) and (28) are duty solenoid valves (II).
) and (13) are pressure sensors (14) and (15) are orifices (20) are regulator lower control chambers (23) are regulator upper chambers (25) are air control valves (27) are suction negative pressure sensors (29) ) is the aperture

Claims (7)

[Claims] (1) In a fuel supply device that has a regulator 3 that vaporizes liquefied petroleum fuel and adjusts the pressure, and controls the fuel with a duty solenoid valve 5 operated by a controller 6, an orifice 14 is installed on the downstream side of the throttle valve of the throttle chamber 7. An air control valve 25 is provided in parallel with this orifice 14. Also, an orifice 15 is provided on the upstream side of the throttle valve, and the orifice 1
5 and an air control valve 25, and a fuel supply system for a liquefied petroleum gas internal combustion engine configured to connect an air control valve 25 to a regulator upper chamber 23 through a synthetic negative pressure passage 16. (2) A fuel supply system for a liquefied petroleum gas internal combustion engine according to claim 1, in which a throttle 29 is installed in the synthetic negative pressure passage 16. (3) In a fuel supply device that has a regulator 3 that vaporizes liquefied petroleum fuel and adjusts the pressure, and controls the fuel with a duty solenoid valve 5 operated by a controller 6, an orifice 14 is provided on the downstream side of the throttle valve of the throttle chamber 7. A duty solenoid valve 28 is provided upstream of the throttle valve, connected to the orifice 14, and connected to the regulator upper chamber 23 from the synthetic negative pressure passage 16.
Connect to. Further, a suction pipe negative pressure sensor 27 is provided in the suction pipe 9. A fuel supply system for a liquefied petroleum gas internal combustion engine configured as described above. (4) A fuel supply system for a liquefied petroleum gas internal combustion engine according to claim 3, wherein a throttle 29 is installed in the synthetic negative pressure passage 16. (5) Fuel supply for a liquefied petroleum gas internal combustion engine according to claim 3, in which the orifice 14 on the downstream side of the throttle valve in the throttle chamber 7 is replaced with a duty solenoid valve, and the duty solenoid valve 28 on the upstream side of the throttle valve is replaced with an orifice. Device. (6) A fuel supply system for a liquefied petroleum gas internal combustion engine according to claim 3, which uses an air flow rate sensor and an engine rotation sensor instead of the suction pipe negative pressure sensor 27. (7) A fuel supply system for a liquefied petroleum gas internal combustion engine according to claim 3, in which a throttle valve opening sensor and an engine rotation sensor are used in place of the suction pipe negative pressure sensor 27.