JPS62251432A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To minimize the deviation from the required ratio of air/fuel by putting the air pressure from an air pump on an fuel measuring device to inject the fuel in a measuring chamber to an engine and introducing the air from the inlet system between a throttle valve and air flow meter to the air pump. CONSTITUTION:Fuel is stored in the measuring chamber of a fuel measuring device 20. And an air pump 30 and air pressure regulator 31 are provided to put air pressure on the fuel measuring device 20 through an air passage 34 for injecting the fuel from a nozzle 16. And air is supplied to the air pump 30 from the inlet system between a throttle valve 14 and air flow meter 13 through a passage 33. This enables the air flow meter to measure the quantity of air for fuel injection and leads to the minimization of the deviation from the required ratio of air/fuel.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a fuel supply system with a fuel metering chamber that measures and stores fuel to be injected into an engine, and uses air pressure to measure and store fuel to be injected into the engine. This invention relates to a fuel injection device for an engine that introduces fuel into the engine.

(Prior Art) A fuel injection device for an engine is known in which a metered amount of fuel to be injected into an engine is stored in a fuel supply system, and this fuel is introduced into the engine using air pressure. For example, JP-A-58-155276 discloses a fuel metering type fuel 131111 engine in which fuel is metered and introduced into the combustion chamber in this manner. The disclosed fuel injection device for an engine includes a metering chamber that stores one dose of fuel to be injected into a combustion chamber, a regulator that changes the volume of the metering chamber, and a regulator that circulates the fuel and supplies the fuel to the metering chamber. Means for filling the metering chamber and means for introducing pressurized air into the metering chamber and discharging fuel from the chamber are provided. Pressurized air is introduced into the metering chamber of the fuel injection device according to the fuel injection timing, and when the pressurized air is introduced, the fuel in the metering chamber is discharged by air pressure. and is introduced into the combustion chamber. In this case, the required amount of fuel to be supplied to the engine changes depending on the operating conditions, but the volume of the metering chamber changes depending on the operation of the regulator.
It can be changed depending on the operating condition so that the above-mentioned required amount of fuel can be stored.

This fuel metering type fuel injection device uses the pressure of pressurized air that forms part of the combustion air to introduce fuel into the combustion chamber together with the air, resulting in good vaporization and combustion. It has the advantage of being able to provide atomization and improve combustibility.

(Problems to be Solved) In a fuel metering type fuel injection device that introduces fuel in a metering chamber into a combustion chamber using pressurized air, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-155276, In this way, fuel vaporization and atomization are improved, and combustibility is improved. When adopting the intake air flow rate sensing method (hereinafter referred to as the L-J method), which determines the amount of air in the combustion chamber based on the A problem arose in that the supplied air was in excess of the fuel injection air 1, and the actual air-fuel ratio inevitably deviated from the optimum air-fuel ratio.

(Object of the Invention) An object of the present invention is to provide the fuel metering type fuel injection device that employs the L-J method and can perform combustion at an air-fuel ratio with little error from the optimum air-fuel ratio. be.

(Structure of the Invention) This object of the present invention is achieved by 7) taking out fuel injection air from the intake pipe between the throttle valve and the air flow meter.

In a preferred embodiment of the present invention, fuel injection air is drawn into the suction side of the air pump through an intake pipe between the throttle valve and the air flow meter, and is pressurized by the air pump.

In another preferred embodiment of the present invention, the output value of the air flow meter at that point in time is averaged by adding the previous output value, and the fuel injection amount is calculated based on the average value, and more preferably, the fuel injection amount is calculated based on the average value. In the rotation range, the fuel injection amount is calculated based on the average value obtained using a large number of air flow meter output values.

(Examples) Hereinafter, examples of the present invention will be described in detail based on the accompanying drawings.

(Configuration of the Embodiment) Referring to FIG. The upper space constitutes a combustion chamber 5. An intake boat 6 and an exhaust port 7 are open to the combustion chamber 5, and an intake valve 8 and an exhaust valve 9 are respectively combined with these boats 6.7. Further, an intake passage 10 and an exhaust passage 11 communicate with the intake port 6 and the exhaust port 7, respectively.An air cleaner 12 is disposed at the upstream end of the intake passage 10, and downstream of the air cleaner 12, An air flow meter 13 is arranged to calculate the amount of intake air.

Furthermore, a throttle valve 14 is disposed downstream of the air flow meter 13 in the intake passage 10.
A surge tank 15 is provided downstream of 4. On the downstream side of this surge tank 15, the intake passage 10 branches into a primary intake passage 10a and a secondary intake passage 10b.
The secondary intake passage 10a is provided with a @ material injection nozzle 16, and the secondary intake passage 10b is provided with a control valve 17 for adjusting the flow area of the passage 10b.

A catalytic converter 18 for purifying exhaust gas is installed in the exhaust passage 11, and a catalytic converter 18 for detecting the oxygen concentration in the exhaust gas and controlling the air-fuel ratio is installed upstream of the catalytic converter 18. An air-fuel ratio sensor 19 is attached.

The fuel supply system of the engine 1 of this embodiment is the fuel injection nozzle 1
A fuel metering device 20 is provided for metering the fuel to be injected from the fuel injection nozzle 6 and sending the metered fuel to the fuel injection nozzle 16. Fuel is supplied from the fuel tank 21 to the fuel pump 2 via the fuel filter 22.
3 will be introduced. Then, the fuel pressurized by the pump 23 is pumped by the fuel pressure regulator 24, and in this example, the fuel is pumped up by the fuel pressure regulator 24.
The pressure is regulated to 1 g/cd, and the fuel is introduced into the fuel metering device 20 via the fuel passage 25. The fuel introduced into the fuel metering device 20 is metered by the device 20 according to the operating state and is injected into the intake air flowing through the intake passage 10 via the fuel injection nozzle 16. On the other hand, excess fuel is returned from the fuel metering device 20 to the fuel tank 21 via the fuel return passage 26. That is, in the fuel supply system of this embodiment, 1, fuel is constantly circulated around the fuel metering device 20, and the required amount of fuel according to the operating condition is injected from the fuel injection nozzle 16 at a predetermined timing. It has become.

In the fuel metering device 20, the introduced fuel is discharged from the fuel metering device 20 and sent to the fuel injection nozzle 16 by air pressure.

In order to apply pneumatic pressure to the fuel metering device 20, the engine l of this embodiment is equipped with a pneumatic system, and this pneumatic system is driven by a belt 29 by a drive pulley 28 attached to the crankshaft 27 of the engine 1. It is composed of an air pump 30 driven through the air pump 30, an air pressure regulator 31 that adjusts the discharge pressure from the air pump 30, and an akinimulator 32 that has a constant volume to alleviate the pulsation of the air discharged from the air pump 30. .

Air introduced into the fuel metering device 20 flows through the intake passage 10 downstream of the air flow meter 13 and upstream of the throttle valve 14.
is drawn into the air pump 30 via the air passage 33,
The pressure is increased by the air pump 30. The pressurized air discharged from the air pump 30 is adjusted to a predetermined pressure by the pneumatic regulator 31, and then passes through the akinimulator 32 and is supplied to the fuel metering device 20 via the air amount 34 in a state in which pulsation is alleviated. will be introduced in

Further, the engine 1 of this embodiment is provided with a controller 35 preferably including a microcombination unit in order to control the operation of the fuel metering device 20 and the pneumatic regulator 31. A signal representing the amount of intake air from the air flow meter 13, a crank angle signal from the crank angle sensor 36 for calculating the engine speed, and a signal from the pneumatic regulator 31 are input to the controller 35. The controller 35 calculates these signals and outputs a predetermined control signal to the fuel metering device 20 and pneumatic regulator 31.

Referring to FIG. 2, the fuel metering device 20 of this embodiment is as follows:
A metering chamber 38 is provided for storing the fuel to be injected from the fuel injection nozzle 16, and the metering chamber 38 has a fuel population 3 communicating with the fuel pump 23 via the fuel passage 25.
A fuel outlet 40 is formed which communicates with the fuel tank 21 via the fuel return passage 26 and the fuel return passage 26 . fuel population 39
The fuel outlet 40 is opened and closed by diaphragm type control valves 41 and 42. The metering chamber 38 also includes a fuel outlet 43 for discharging the fuel within the chamber 38, and the fuel outlet 43 communicates with the fuel injection nozzle 16 via a fuel passage 44. A check valve 47 constituted by a ball member 45 and a spring member 46 is combined with the fuel discharge port 43, and the discharge port 43 is normally closed by the biasing force of the spring member 46. .

Furthermore, an adjustment body 48 is arranged in the metering chamber 38 for changing the volume of the chamber 38 . The adjusting body 48 is composed of a hollow cylindrical member 49 and an adjusting rod 50 that is inserted into the cylindrical member 49 and arranged in advance. The adjustment body 48 is supported by a hub 51, and the hub 51 is connected to a linear motor 53 via a link member 52. The linear motor 53 is driven by a control signal from the controller 35 so that the adjusting body 48 can be moved to any vertical position in the figure via the link member 52 and the hub 51. It has become.

That is, due to the operation of the linear motor 53, the adjustment body 48
The position of the lower end of the metering chamber 38 changes, thereby causing the metering chamber 38
capacity can be changed.

An adjustment rod 50 is provided in the opening 49a at the lower end of the cylindrical member 49.
A valve body 50a formed at the lower end of the valve body 50a is combined with the valve body 50a. In this case, in the normal state, the adjustment valve 50 is urged upward in the figure by a spring member 54 disposed between a flange portion 50b formed at the upper end and the upper end of the cylindrical member 49, and the valve body 50a is The opening 49a is closed. The upper portions of the cylindrical member 49 and the adjustment rod 50 project into the air chamber 55 . Pressurized air is introduced into the air chamber 55 via an air passage 57 that communicates with the air passage 34 downstream of the air pressure regulator 31.
A solenoid valve 58 for controlling the introduction of pressurized air into the air chamber 55 is disposed in the air passage 57 . This solenoid valve 58 is opened and closed by a control signal from the controller 35. Further, the air passage 57 branches downstream of the solenoid valve 58 and communicates with control valves 43 and 44 that open and close the fuel outlet 39 and the fuel outlet 40.

(Operation) To explain the operation of the device with the above structure, the control 35 performs predetermined calculations based on signals from various sensors, and controls the fuel metering device 20 and the pneumatic regulator 3.
Outputs a command signal for 1. In this case, the controller 35 calculates the fuel injection amount based on the output signal of the air meter 13, outputs a signal to the linear motor 53 as shown in FIG. The position of the adjustment body 48 is adjusted to correspond to the following.

As shown in FIG. 4, when the cylinder is not in the injection period, the fuel inlet 39 and fuel outlet 40 of the metering chamber 38 are open, and the fuel outlet 43 and the opening 49a of the cylindrical member 49 are open. Since it is closed, fuel is circulating through the fuel system around metering chamber 38.

When performing fuel injection, the controller 35
outputs a signal to the control solenoid 58a of the solenoid valve 58 in accordance with the injection timing of each cylinder, and controls the solenoid valve 58 to open only for a predetermined period.

When the solenoid valve 58 opens, pressurized air flows into the air chamber 55 through the air passage 57, and its pressure pushes down the adjusting rod 50 against the biasing force of the spring member 54, as shown in FIG. , the opening 49a at the lower end of the cylindrical member 49 is opened. In this case, the pressurized air flows into the air chamber 55 and simultaneously acts on the diaphragms 41a of the control valves 41 and 42 via the air passage 57, closing the valves 41 and 42.

This allows pressurized air to flow from the air chamber 55 through the interior of the cylindrical member 49 and from the opening 49a into the metering chamber 38.
The fuel in the chamber 38 is discharged from the fuel outlet 43. The fuel discharged from the fuel discharge port 43 is injected into the intake passage 10 from the fuel injection nozzle 16.

In this embodiment, the amount of fuel injection air is measured by the air flow meter 13 and used as the basis for calculating the fuel injection amount, so even if the fuel is injected with pressurized air, the desired air-fuel ratio This makes it possible to minimize the deviation.

FIG. 6 ASBSC shows a flowchart showing an example of fuel injection control according to the present invention. FIG. 6A shows the main routine, FIG. 6B shows a subroutine for stratifying the fuel, and FIG. 6C shows a graph showing the basic injection amount correction method based on the engine speed. are shown respectively. In FIG. 6A, after the system is initialized, the engine speed, intake air amount, throttle valve opening, atmospheric pressure, intake air temperature, water temperature, etc. (not shown in FIG. 1) are controlled by the controller 35. Loaded.

The controller 35 calculates the basic fuel injection amount based on these input values, but in the present invention, since the L-J method is adopted, the basic fuel injection amount is calculated based on the intake air amount. .

Next, the calculated basic fuel injection amount is corrected based on the engine speed, atmospheric pressure, intake temperature, water temperature, acceleration state, etc., as necessary. FIG. 6C shows a method of correcting the basic fuel injection amount based on the engine speed. That is, in the present invention, since fuel injection air is also sent to the combustion chamber, if this is not taken into consideration when calculating the air-fuel ratio, pressurized air injection will cause a deviation from the desired air-fuel ratio. After measuring the intake air amount with the air flow meter 13, a part of the measured air is used as fuel injection air, and the air thus taken out to the pneumatic system is introduced into the combustion chamber. It is inevitable that there will be some time delay. Therefore, in order to compensate for the time delay in introducing pressurized air and minimize the deviation from the desired air-fuel ratio, the basic fuel injection amount is not calculated only based on the intake air amount detected at a certain point in time. In this embodiment, the previously detected intake air amount data is stored in the controller 35, and the basic fuel injection amount is calculated based on the average value of the intake air amount detected several times. It has been adopted. Figure 6C samples a larger number of intake air amount detection values in the lower rotation speed range, based on the knowledge that the error due to this time delay is large in the low rotation speed region and becomes smaller as the rotation speed increases. This shows that the average value is calculated and the fuel injection amount is corrected. It can be seen from FIG. 6C that averaging is not necessary in the high rotation range. The graph shown in FIG. 6C is determined experimentally, and it goes without saying that it is not limited to a straight line as shown, but may also be a curved line. The air injection period is then controlled, and in the example of FIG. 6A, BSC, the injection time is controlled for fuel stratification. FIG. 6B shows a subroutine for this purpose. First, the engine speed, intake air amount, and injection air pressure are input manually to the controller 35. When these are input, the best timing for fuel stratification determined experimentally is stored in advance in the form of a map in the controller 35, so the controller 35
The pressurized air injection start timing is calculated, and the injection period and injection end timing Tsp are also calculated. On the other hand, the controller 35 stores the injection end timing for stratification, that is, the timing "I'spo" to close the intake valve 9, and Tsp and Tsp.
If Tsp > Tspo, it means that the injection will not end by the time Tspo when the injection should end, so an air pressure signal is output to the air regulator 31, and the difference signal of Tsp - Tspo is Based on this, the pressure of the injection air is adjusted, and the injection is controlled to end by the time when the injection should end. On the other hand, Tsp
When ≦Tspo, a signal is output to the pneumatic regulator 31 indicating that the pneumatic pressure should be maintained at the current pneumatic pressure. thus,
The pressurized air injection period is controlled, and when the injection timing is reached, the pressurized air is injected.

It goes without saying that the present invention is not limited to the embodiments described above, and that various changes can be made within the scope of the invention as set forth in the claims.

(Effects of the Invention) According to the present invention, it is possible to promote atomization and vaporization of fuel and improve combustibility while minimizing deviation from a desired air-fuel ratio.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention, FIG. 2 is a sectional view of a fuel metering device, and FIGS. 3, 4, and 5 show operating states of the fuel metering device. Sectional view, No. 6
FIG. ASB is a flowchart showing an example of fuel injection control, and FIG. 6C is a graph showing an example of a basic injection amount correction method. l...Engine, 2...Cylinder block, 3...Cylinder bore, 4...Piston,
5... Combustion chamber, 6... Intake port, 7...
...Exhaust port, 8...Intake valve, 9...Exhaust valve, lO...Intake passage, 11...Exhaust passage, 12...Air cleaner, 13...
Air flow meter, 14... Throttle valve, 15... Surge tank, 16... Fuel injection nozzle, 20... Fuel metering device, 21... Fuel tank, 22... Fuel filter, 23...・Fuel pump, 27...Crankshaft, 30...Air pump, 31...Pneumatic regulator, 32...Akinyi regulator, 35...Controller, 38...Total 1 chamber, 39...・Fuel population, 4o...Fuel outlet, 41.42...Control valve, 43...Fuel discharge port,
44... fuel passage, 48... adjustment body, 49...
...Cylindrical member, 5o...Adjustment rod, 53.
...'J=7%-ta, 55...air chamber,
58...Solenoid valve, 58a...it 6'l valve solenoid.

Claims (1)

[Claims] A throttle valve is installed in the intake system to control the amount of intake air; an air flow meter is installed in the intake system upstream of the throttle valve to measure the amount of intake air; and an air flow meter is installed in the fuel supply system to measure the required amount of fuel. A metering chamber for storing fuel, a regulating body that changes the volume of the metering chamber to give a predetermined fuel injection amount, and calculating the fuel injection amount based on the output of the air flow meter and controlling the position of the regulating body. a controller; a pressurizing means for applying air pressure to discharge the fuel stored in the metering chamber from the metering chamber in order to supply the fuel stored in the metering chamber to the engine at a predetermined timing; and supplying pressurized air to the pressurizing means. What is claimed is: 1. A fuel injection device for an engine including an air pump for supplying air, wherein air is taken out from an intake system between the throttle valve and the air flow meter and guided to the air pump.