JPS63147937A - Fuel supply device for engine - Google Patents

Abstract

PURPOSE:To reduce the cost with a relatively simple construction, by providing a displacing member for contracting a gasoline storing volume of a volume section and a selecting means for applying a methanol fuel pressure to the displacing member. CONSTITUTION:Main fuel injectors 4a-4d are arranged for cylinders 1a-1d, respectively. A diaphragm device 25 includes a fuel pressure inducing chamber 25b, a gasoline inducing chamber 25c and a spring 25d. A selector valve 27 is connected to the fuel pressure inducing chamber 25b. When a methanol fuel pressure downstream of a fuel supply pump 10 is induced, a diaphragm 25a is deflected downwardly by the methanol fuel pressure to thereby contract the gasoline inducing chamber 25c and feed the gasoline to an auxiliary fuel injector 5 under pressure.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a fuel supply system for an engine that uses methanol as the main fuel, and in particular to a fuel supply system for an engine that uses methanol as the main fuel. Concerning the improvement of something that is intended to improve.

(Prior Art) Conventionally, as a fuel supply device for this type of engine, methanol is supplied as the main fuel during normal operation except for startup, as disclosed in, for example, Japanese Patent Application Laid-Open No. 58-4875'9@. On the other hand, since the vaporization and atomization performance of methanol decreases when starting the engine, especially during low-temperature starts, it is necessary to supply gasoline with good vaporization and atomization performance to the engine as auxiliary fuel. There are known devices designed to improve the performance.

(Problem to be Solved by the Invention) However, in that case, in order to supply gasoline as auxiliary fuel, it is necessary to separately provide a fuel supply pump for auxiliary fuel in addition to the fuel supply pump for main fuel. , resulting in costly drawbacks.

Furthermore, since the auxiliary fuel is used only during startup, and the fuel supply pump is used infrequently, it is not preferable to provide it separately.

The present invention has been made in view of the above, and its object is to supply gasoline to the engine using the methanol fuel pressure of the main fuel as a driving force, at least when supplying gasoline as an auxiliary fuel when starting the engine at a low temperature. 1q, it is possible to supply gasoline at low temperature startup without installing a fuel supply pump for auxiliary fuel, thereby reducing costs.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention supplies methanol from a fuel supply pump to the engine as the main fuel, and supplements gasoline at least when starting the engine at a low temperature. This assumes a fuel supply system for an engine that supplies fuel to the engine. and a gasoline injection valve for injecting gasoline into the engine; a volume portion disposed in a gasoline supply passage to the gasoline injection valve and having a volume for storing gasoline; A displacement member that reduces the volume of the volume portion, and at least a low-temperature container of the engine.
A switching means is provided for causing the methanol fuel pressure of the fuel supply pump to act on the displacement member when the engine is stopped, and for stopping the action of the methanol fuel pressure when the engine is stopped.

(Function) With the above configuration, in the present invention, at least when the engine is started at a low temperature, the methanol fuel pressure of the main fuel acts on the displacement member by the switching means, and the displacement of the displacement member causes the volume in the middle of the gasoline supply passage to increase. The volume of the fuel tank is reduced, and gasoline (auxiliary fuel 1) is single-handedly pumped from the volume tank to the gasoline injection valve, and then injected and supplied to the engine from the gasoline injection valve, resulting in good vaporization of the fuel. The improved engine performance makes it easier for the engine to move. After the above single injection of gasoline, methanol (main fuel) is supplied from the fuel supply pump to the engine as usual, and the engine continues to operate.

In this case, the single injection supply of gasoline when the engine is started at a low temperature is performed by reducing the volume of the displacement member in accordance with the displacement of the displacement member based on the action of the methanol fuel pressure. Now that supply is possible,
There is no need to separately provide a fuel supply pump for gasoline, and costs can be reduced.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a fuel supply system for an engine according to the present invention, in which 1 is an engine having four cylinders 1a to 1d, 2 is an engine having four cylinders 1a to 1d;
is an intake passage whose one end communicates with the atmosphere and whose other end branches into four parts, each of which communicates with each cylinder 1a to 1d of the engine 1; A throttle valve 3 is disposed downstream of the branching part of the intake passage 2, and four throttle valves are installed downstream of the branching part of the intake passage 2 to inject methanol distributed in all directions as the main fuel to each cylinder 1a to 1d. Main fuel injection valves 4a to 4d are arranged.

Further, an auxiliary fuel injection valve 5 is arranged downstream of the throttle valve 3 of the intake passage 2 and upstream of the branch part, and serves as a gasoline injection valve that concentrates gasoline as auxiliary fuel in one direction and injects it into the engine 1. There is.

The above-mentioned four main fuel injection valves 4a to 4d are connected in parallel to each other, and are connected to a main fuel tank 9 that stores methanol therein through a secondary supply passage 8 to supply the main fuel. A fuel supply pump 10 is interposed in the middle of the passage 8 for sucking methanol from the main fuel tank 9 and discharging it to the main fuel injection valves 4a to 4d. The main fuel is injected and supplied to the engine 1 from four sub-strands 7'F1 injection q] valves 4a to 4d.

Further, a fuel 11 pressure regulating valve 13 for main fuel is connected to the main fuel supply passage 8 via a methanol fuel pressure introduction passage 12, and the fuel pressure regulation valve 13 is connected to the main fuel supply passage 8 via a negative pressure introduction passage 14. Intake negative pressure directly downstream of the throttle valve 3 of the intake passage 2 is introduced thereinto, and is also communicated with the main fuel tank 9 via the return passage 15 and the main fuel supply passage 8 upstream of the fuel supply pump 10. When the methanol fuel pressure is higher than the intake negative pressure by more than a set value, the methanol discharged from the fuel supply pump 10 is returned to the main fuel tank 9 via the return passage 15, so that the methanol fuel pressure is higher than the set value than the intake negative pressure. It functions to hold the temperature at a high level.

On the other hand, the auxiliary fuel injection valve 5 is connected to the gasoline supply passage 18
The gasoline supply passage 18 is connected to an auxiliary fuel tank 19 for storing gasoline, and a check valve 20 is provided in the middle of the gasoline supply passage 18 to allow fuel to flow in the direction from the auxiliary fuel tank 19 to the auxiliary fuel injection valve 5. A diaphragm device 25 is interposed in the gasoline supply passage 18 on the downstream side of the check valve 20 .

The diaphragm device 25 includes a fuel pressure introduction chamber 25b divided into upper and lower sections by a diaphragm 25a as a displacement member.
and a gasoline introduction chamber 25C as a volumetric part, and a spring 25d compressed in the gasoline introduction chamber 25C. is connected. The switching valve 27 controls the pressure in the main fuel supply passage 8 on the downstream side of the fuel supply pump 10 introduced via the pressure introduction passage 28;
In other words, the methanol fuel pressure and the combustion introduced via the other pressure introduction passage 29! The pressure in the main fuel supply passage 8 on the upstream side of the supply pump 10 is selectively switched to be guided to the fuel pressure introduction chamber 25b of the diaphragm device 25 via the fuel pressure introduction passage 26. When the upstream pressure of the fuel supply pump 10 is introduced into the fuel pressure introduction chamber 25a, the diaphragm (displacement member) 25a is biased upward by the urging force of the spring 25d, thereby expanding the gasoline introduction chamber (volume portion) 25C. As a result, while the gasoline in the auxiliary fuel tank 19 is sucked into the gasoline introduction chamber 25C via the check valve 20 and stored therein, when the downstream pressure (methanol fuel pressure) of the fuel supply pump 10 is introduced, By biasing the diaphragm (displacement member) 25a downward against the biasing horn of the spring 25d by the methanol fuel pressure, the gasoline introduction chamber (volume portion) 2
5C is reduced to forcefully feed gasoline in the intake chamber 25c to the auxiliary fuel injection valve 5.

Note that the diaphragm device 25 has a fuel pressure introduction chamber 25b.
An auxiliary fuel amount detection switch 31 is disposed inside the fuel tank and detects the amount of gasoline in the gasoline introduction chamber 25C in conjunction with the diaphragm 25a, and is turned ON when the amount is less than a set value.

The four main fuel injection valves 4a to 4d, the auxiliary fuel 1
The operation of the 1 injection valve 5 and the switching valve 27 is controlled by a controller 35 each having a built-in CPU, etc., and the controller 35 receives an ignition signal, a battery voltage signal, a starter signal, which is generated when the key switch is turned on,
A throttle position signal, an intake air temperature signal, an engine cooling water temperature signal, an air-fuel ratio signal, and an auxiliary fuel amount signal from the auxiliary fuel amount detection switch 31 are displayed in a panoramic view.

Next, the operation of the controller 35 will be explained with reference to the control flow shown in FIG. After the engine starts, it is determined in step S1 whether or not an ignition signal is received. If no ignition signal is received, it is determined that the engine is stopped, and fuel is supplied into the fuel pressure introduction chamber 25b of the diaphragm device 25 in step S2. The switching valve 27 is controlled to switch so that the pressure on the upstream side of the pump 10 is introduced into the gasoline introduction chamber 25C.
Store gasoline inside and return.

On the other hand, when starting the engine with the reception of the ignition signal in step S1, the auxiliary fuel amount signal from the auxiliary fuel amount detection switch 31 is first input in step S3, and then gasoline is introduced in step S4 based on the auxiliary fuel amount signal. When the amount of fuel in the chamber 25c is ascertained, and if it is less than the set value, the process returns to step S2 and the fuel pressure introduction chamber 2
The switching valve 27 is controlled to introduce the pressure on the upstream side of the fuel supply pump 10 into the fuel supply pump 5b, and a predetermined amount of gasoline is stored in the gas introduction chamber 25C, and then the fuel is returned.

Further, if the amount of heating is equal to or higher than the predetermined level in step S4, the engine coolant temperature signal QTE is input in step S5, and the set value T corresponding to when the engine coolant temperature TE is warm is input in step S6.

It is determined whether or not the above is true, and when TE≧To (YES) is warm, it is determined that there is no need to start by gasoline injection, and the process returns to step S2, with a predetermined amount of gasoline still stored.

Then, in step S6, when the temperature is low (TE < To), the switching valve 27 is controlled to introduce methanol fuel pressure into the fuel pressure introduction chamber 25b in step S7, and auxiliary fuel is supplied from the diaphragm device 25 in order to start by gasoline injection. pressure-feeding gasoline to the auxiliary fuel injection valve 5,
Gasoline is injected into the engine 1 singly from the auxiliary fuel injection valve 5. Thereafter, in step S8, it is determined whether or not the engine 1 has completely exploded due to the injection of gasoline, and if NO, the process returns to step S1 to repeat the single injection of gasoline. , If YES is complete explosion, the auxiliary fuel injector 5 is activated in step $9.
It is determined whether the valve is closed or not, and if the valve is open, the process returns to step S7 and the state is maintained.
In step Sho, the fuel supply pump 1 is installed in the fuel pressure introduction chamber 25b in preparation for the next startup.
The switching valve 27 is switched and controlled so as to introduce the pressure horn on the 0 upstream side, and gasoline is stored in the gasoline introduction chamber 25C.

Therefore, according to the control flow shown in FIG. 2 above, when the engine is started at a low temperature, the methanol fuel pressure in the main fuel supply passage 8 on the downstream side of the fuel supply pump 10 is introduced into the fuel pressure introduction chamber 25b of the diaphragm device 25, and this methanol fuel pressure is While acting on the diaphragm 25a, after the engine is started, the fuel pressure is supplied to the fuel pressure introduction chamber 25b from the time when the engine is in operation until the next cold start of the engine, including the subsequent engine stop state.
Stop applying the methanol fuel pressure to the diamond.

Switching means 3 capable of stopping the action on the flamm 25a
6.

Therefore, in the above embodiment, the diaphragm device 2
The inside of the gasoline introduction chamber 25c of No. 5 is normally filled with a spring 25.
The gasoline introduction chamber 25c is expanding with the extension operation of d, and is ready to store gasoline.

Then, when the engine is started at a low temperature next time, the switching valve 27
As a result, the methanol fuel pressure of the fuel supply pump 10 is introduced into the fuel pressure introduction chamber 25b of the diaphragm device 25, and the diaphragm 25a is biased downward, whereby the gasoline introduction ff125c is reduced and the gasoline in the gasoline introduction chamber 25C is supplemented. Since the fuel is discharged as fuel and injected into the engine 1 from the auxiliary fuel injection valve 5 via the gasoline supply passage 18, the engine can be started relatively easily due to the good vaporization and atomization performance of the Karin. You will be attacked.

Then, after the engine is started, the switching valve 27 is switched again, the introduction and application of methanol fuel pressure to the fuel pressure introduction chamber 25b is stopped, and the gasoline introduction chamber 25C is again switched to the spring 2.
5d, the fuel in the auxiliary fuel tank 19 flows through the check valve 20 into the gasoline introduction chamber 2.
It is sucked into 5C and prepared for the next engine start.

Here, since the gasoline supply at the time of engine startup is performed by reducing the gasoline introduction W25c according to the displacement of the diaphragm 25a based on the action of methanol fuel pressure, there is no need to separately install a fuel injection pump exclusively for gasoline. , it is possible to achieve cost reduction.

In the above embodiment, after the engine is started, the application of methanol fuel pressure is immediately stopped to store gasoline for the next start in the gasoline introduction chamber 25c of the diaphragm device 25. When the engine is stopped, the application of methanol fuel pressure may be stopped to prepare for the next start.

Further, FIG. 3 shows another embodiment of the present invention, and in the embodiment described in -F, when applying methanol fuel pressure to the diaphragm device 25, gasoline at a fuel pressure corresponding to the contraction operation of the gasoline introduction chamber 25C is directly assisted. Instead of pressure feeding the fuel to the fuel injection valve 5, a pressure regulating valve 40 is provided to maintain the gasoline fuel pressure at a set value.

That is, the pressure regulating valve 40 is adjusted so that the gasoline fuel pressure gradually decreases in response to the contraction operation of the spring 25d of the gasoline introduction chamber 25c, and opens at a gasoline fuel pressure equal to or higher than the maximum contraction of the spring 25d. By setting the amount valve pressure, the fuel pressure is always maintained at the above amount valve pressure, and the gasoline injection R is maintained at a constant value.

In the above embodiment, gasoline is supplied only when the engine is started at a low temperature, but it is of course possible to supply gasoline at all times when the engine is started.

(Effects of the Invention) As explained above, according to the engine fuel supply device of the present invention, instead of supplying methanol as the main fuel at the time of starting, Ganlin is supplied as an auxiliary fuel based on the methanol fuel pressure. Since the gasoline is supplied under pressure to the engine through the injection valve, it is possible to supply gasoline at the time of starting the engine with a relatively simple configuration, eliminating the need for a fuel supply pump for auxiliary fuel. Cost reduction can be achieved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a general schematic diagram, Fig. 2 is a flowchart showing the operation of the controller, and Fig. 3 shows another embodiment of the invention. It is. 1... Engine, 4a-4d... Main fuel injection valve, 5
... Auxiliary fuel injection valve, 10 ... Fuel supply pump, 1
8... Gasoline supply passage, 20... Check valve, 25...
...Diaphragm device, 25a...Diaphragm, 2
5b...Fuel pressure introduction chamber, 25C...Gasoline introduction chamber,
27...Switching valve, 35...Controller, 36...
・Switching means. shimo ramie

Claims (1)

[Claims] (1) A fuel supply system for an engine, which supplies methanol from a fuel supply pump to the engine as a main fuel, and also supplies gasoline to the engine as an auxiliary fuel at least when the engine is started at a low temperature. A gasoline injection valve that injects gasoline, a volume part that is arranged in a gasoline supply passage to the gasoline injection valve and has a volume for storing gasoline, and a volume of the volume part that is displaced by methanol fuel pressure of the fuel supply pump to reduce the volume of the volume part. and a switching means for causing the methanol fuel pressure of the fuel supply pump to act on the displacement member at least when the engine is started at a low temperature, and for stopping the action of the methanol fuel pressure when the engine is stopped. Engine fuel supply system.