JPS62251430A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To improve the acceleration characteristics of an engine by raising the air pressure for supplying the engine with the fuel in a measuring chamber by a specified value while in accelerating the engine. CONSTITUTION:An air pump 30 driven by the crank shaft 27 of an engine 1 and an air pressure regulator 31 are provided to introduce pressure air into a fuel measuring device 20 through an air passage 35 for supplying the fuel in a measuring chamber to the engine. And while in accelerating the engine, the output signals from a controller 36 controls the air pressure regulator 31 to pressure air higher by a specified value into the fuel measuring device. This leads to the improvement of the acceleration characteristics of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention includes a fuel metering chamber for measuring and storing fuel to be injected into an engine in a fuel supply system, and uses air pressure to measure and store fuel to be injected into an engine. The present 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 that measures and stores a single dose of fuel to be injected into an engine in a fuel supply system, and introduces this fuel into the engine using air pressure. For example, Japanese Patent Laid-Open No. 58-155276 discloses a fuel injection type 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 state, and the volume of the metering chamber changes depending on the operating state so that the above-mentioned required amount of fuel can be stored by the operation of the regulator. It is now possible to do so.

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 of the fuel. 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, As described above, although the effect of improving fuel vaporization and atomization and improving combustibility is obtained, it is still difficult to obtain desired acceleration performance during acceleration. In other words, in order to achieve good acceleration performance, it is necessary to inject fuel as quickly as possible in response to the acceleration signal from the throttle pedal, etc., and to further promote atomization of the fuel. In the conventional device described above, the only device that has been devised is to inject measured fuel using air to promote vaporization and atomization of the fuel. Sufficient acceleration performance could not be obtained due to the delay in fuel injection response due to the passage length.

In this case, it may be possible to set the air pressure to a high pressure in advance, but doing so will improve the controllability of the mixture amount and increase the amount of fuel adhering to the intake passage in areas where the intake air amount is small, such as during low load. etc. occur, which is not desirable.

(Objective of the Invention) An object of the present invention is to provide the fuel metering type fuel injection device having excellent acceleration characteristics.

(Structure of the Invention) This object of the present invention is achieved by providing means for controlling the pressure of air for discharging fuel depending on the acceleration state.

In the present invention, how to control the air pressure should be determined experimentally so as to obtain the desired acceleration characteristics in consideration of the relationship with the engine characteristics, but preferably the throttle depression speed, that is, It is desirable to control the air pressure according to the rate of change dθ/dt of the opening degree θ of the throttle valve. FIG. 1 shows an example in which the air pressure is controlled by increasing linearly with respect to the rate of change dθ/dt of the opening degree θ of the throttle valve.

As a method for controlling air pressure in the present invention, the air pressure control algorithm predetermined as described above is stored in an air pressure control means preferably including a microcombination unit, for example, in the form of a table. The method includes a method of controlling the air pressure as desired by causing the air pressure adjusting means to output an air pressure control signal calculated based on an input signal indicating the acceleration state.

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

(Configuration of Embodiment) Referring to FIG. 2, the engine 1 of this embodiment includes a piston 4 that reciprocates within a cylinder bore 3 formed in a cylinder block 2, and a space above the piston 4 of the cylinder bore 3. constitutes the combustion chamber 5. An intake port 6 and an exhaust port 7 are open to the combustion chamber 5, and an intake valve 8 and an exhaust valve 9 are combined with these ports 6.7, respectively. 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 installed at the upstream end of the intake passage 10, and an air flow meter 13 for measuring the amount of intake air is installed downstream of the air cleaner 12.

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. On the downstream side of the surge tank 15, the intake passage 10 branches into a primary intake passage 10a and a secondary intake passage 10b, and a fuel injection nozzle 16 is installed in the primary intake passage lOa.
Each of the secondary intake passages 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 measuring bag that measures the fuel to be injected from 6 and sends it to the fuel injection nozzle 16! It is equipped with t20. Fuel is introduced from the fuel tank 21 to the fuel pump 23 via the fuel filter 22. Then, the pressure of the fuel increased by the pump 23 is regulated by the fuel pressure regulator 24 to about 1 kg/cm<2 >in this embodiment, and then 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, the excess fuel is stored in the fuel metering device 2.
0 and is returned to the fuel tank 21 via the fuel return passage 26. That is, in the fuel supply system of this embodiment, fuel is constantly circulated around the fuel metering device 20, and the required amount of fuel depending on 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 1 of this embodiment is equipped with a pneumatic system. 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 is drawn into the air pump 30 from the intake passage 10 downstream of the air flow meter 13 via the air passage 33, and is pressurized by the air pump 30. The pressurized air discharged from the air pump 30 passes through the air passage 34 and is adjusted to a pressure set according to the acceleration state by the pneumatic regulator 31, and then passes through the akinimulator 32, where the pulsation is alleviated. , is introduced into the fuel metering device 20 via the air passage 35.

Further, the engine 1 of this embodiment is provided with a controller 36 preferably including a microcomputer in order to control the operations of the fuel metering device 20 and the air pressure 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 37 for calculating the engine speed, and a signal representing the opening degree θ of the throttle valve 14 are input to the controller 36. Controller 3
6 calculates these signals and outputs predetermined control signals to the fuel metering device 20 and the air pressure regulator 31.

FIG. 3 shows details of the pneumatic regulator 31.
In this embodiment, a gap between the air passage 38 for returning air to the air pump 30 and the air passage 38 is defined.
A diaphragm 39 adjusts the pressure of air supplied to the air pressure regulator 31 and introduced into the fuel metering device 20 via the air passage 35 to a desired value, and a controller 36 based on a detection signal of the opening degree θ of the throttle valve. It is comprised of a slide/id 41 that adjusts the position of the stopper of the spring member 40 in response to an output air pressure setting signal and operates so that the diaphragm 39 is set at a position that provides a desired air pressure. Here, the solenoid 38 can be replaced with a motor.

Referring to FIG. 4, the fuel metering device 20 of this embodiment is as follows:
The metering chamber 42 stores fuel to be injected from the fuel injection nozzle 16, and the metering chamber 42 has a fuel population 4 connected to the fuel pump 23 via a fuel passage 25.
A fuel outlet 41 is formed which communicates with the fuel tank 21 through the fuel tank 21 and the fuel return passage 26 . fuel population 43
The fuel outlet 44 is opened and closed by diaphragm type control valves 45 and 46. The metering chamber 42 also includes a fuel outlet 47 for discharging the fuel within the chamber 42, and this fuel outlet 47 communicates with the fuel injection nozzle 16 via a fuel passage 48. A check valve 51 constituted by a ball member 49 and a spring member 50 is combined with the fuel discharge port 47, and the discharge port 44 is normally closed by the biasing force of the spring member 50.

Furthermore, an adjustment body 52 for changing the volume of the metering chamber 42 is arranged within the metering chamber 42 . The adjusting body 52 is composed of a hollow cylindrical member 53 and an adjusting rod 54 that is inserted into the cylindrical member 53 and arranged in a vertical direction. The adjusting body 52 is supported by a hub 55, which is connected to a linear motor 57 via a link member 56. The linear motor 57 is driven by a control signal from the controller 36, and can move the adjusting body 52 to any vertical position in the figure via the link member 56 and the hub 55. ing.

That is, due to the operation of the linear motor 57, the adjusting body 52
The position of the lower end of the metering chamber 42 changes, thereby causing the metering chamber 42
capacity can be changed.

An adjustment rod 54 is provided in the opening 53a at the lower end of the cylindrical member 53.
A valve body 54a formed at the lower end of the valve body 54a is combined with the valve body 54a. In this case, in the normal state, the adjustment rod 54 is urged upward in the figure by a spring member 58 disposed between a flange portion 54b formed at the upper end and the upper end of the cylindrical member 53, and the valve body 54a is The opening 53a is closed. The upper portions of the cylindrical member 53 and the adjusting rod 54 project into the air chamber 59 . Pressurized air is introduced into the air chamber 59 via an air passage 61 that communicates with the air passage 35 downstream of the air pressure regulator 31.
A solenoid valve 62 for controlling the introduction of pressurized air into the air chamber 59 is disposed in the air passage 61 . This solenoid valve 62 is opened and closed by a control signal from the controller 36. Further, the air passage 61 branches downstream of the solenoid valve 62 and communicates with control valves 45 and 46 that open and close the fuel port 43 and the fuel outlet 44 .

(Operation) To explain the operation of the device with the above structure, the controller 36 performs predetermined calculations based on signals from various sensors, and controls the fuel metering device 20 and the air pressure regulator 31.
Outputs a command signal to. In this case controller 3
6 calculates the fuel injection amount according to the operating state of the engine 1, outputs a signal to the linear motor 57, and controls the adjustment body so that the capacity of the metering chamber 42 corresponds to the fuel injection amount as shown in FIG. Adjust the position of 52.

As shown in FIG. 6, when the cylinder is not in the injection period, the fuel outlet 43 and fuel outlet 44 of the metering chamber 42 are open, and the fuel outlet 47 and the opening 53a of the cylindrical member 53 are open. Since it is closed, fuel is circulating through the fuel system around metering chamber 42.

Then, when performing fuel injection, the controller 36 outputs a signal to the control solenoid 62a of the solenoid valve 62 in accordance with the injection timing of each cylinder, and controls the solenoid valve 62a for a predetermined period.
2 is controlled to open.

When the solenoid valve 62 opens, pressurized air flows into the air chamber 59 through the air passage 61, and its pressure pushes down the adjustment rod 54 against the biasing force of the spring member 58, as shown in FIG. , the opening 53a at the lower end of the cylindrical member 53 is opened. In this case, the pressurized air flows into the air chamber 59 and simultaneously acts on the diaphragms 45a of the control valves 45 and 46 via the air passage 61, closing the valves 45 and 46.

Thereby, pressurized air passes from the air chamber 59 through the interior of the cylindrical member 53 and from the opening 53a to the metering chamber 42.
The fuel in the chamber 42 is discharged from the fuel outlet 47. The fuel discharged from the fuel discharge port 47 is injected into the intake passage 10 from the fuel injection nozzle 16.

In this embodiment, pressurized air adjusted to a desired pressure by the pneumatic regulator 31 is supplied to the fuel metering device 20 via the air passage 55 based on a signal output from the controller 36 in accordance with the acceleration state of the engine. is being sent to. A method for adjusting the air pressure in the air pressure regulator 31 based on the output signal from the controller 36 will be described below with reference to the flowcharts shown in FIGS. 8A and 8B.

Crank angle sensor 37 for calculating engine speed
A crank angle signal from the air flow meter 13, a signal representing the intake air amount from the air flow meter 13, and a signal representing the opening degree θ of the throttle valve 14 are manually input to the controller 36, and the controller 36 performs predetermined calculations based on these signals. , calculate the basic injection amount. Next, the air pressure of the fuel injection air is controlled according to the air pressure control subroutine shown on the eighth father's day. The opening degree θ of the throttle valve 14 is read periodically, and the previously read opening degree θ1 and the currently read opening degree θ2 are compared.

When θ1≧02, that is, when no acceleration is performed, the air pressure is set to the basic air pressure corresponding to the case where the rate of change dθ/dt of the opening degree θ of the throttle valve 14 is zero. On the other hand, when θ1 and θ2, that is, when accelerating, for example, the air pressure to be set for the experimentally determined rate of change dθ/dt of the opening degree θ of the throttle valve 14 as shown in FIG. Since the relationship is stored in advance in the controller 36, a desired air pressure corresponding to the calculated rate of change dθ/dt of the opening degree θ of the throttle valve 14 is calculated, and the air pressure is set to that value. Also, Figure 8A
, B, the controller 36 is stored with a relationship between the air pressure obtained by the pneumatic regulator 31 and the excitation voltage of the solenoid 41, which has been determined experimentally in advance. The excitation voltage of the solenoid 41 that provides the desired air pressure is calculated and output to the air pressure regulator 31. Based on this signal, the solenoid 41 of the air pressure regulator 31 adjusts the position of the stopper of the spring member 40, and the diaphragm 39 is positioned so as to apply a predetermined air pressure. After the air pressure is set in this way, when the fuel injection timing is reached, air at a predetermined pressure is injected, and fuel is promptly supplied to the intake valve 8.

In this way, in this embodiment, the throttle valve 1
The pressure of the pressurized air for fuel injection is controlled according to the rate of change dθ/dt of the opening degree θ in step 4, and the fuel is injected with higher pressure air during acceleration, so the injection speed is high. At the same time, it is possible to further promote fuel atomization and improve acceleration response.

In the above embodiment, an example of the so-called acceleration synchronized injection type was shown in which fuel is injected at a predetermined injection timing even during acceleration, but when acceleration is performed, fuel is injected without waiting for the injection timing When the present invention is applied to a so-called acceleration asynchronous type in which fuel is injected, the acceleration response is further improved, which is desirable.

(Effects of the Invention) According to the present invention, by controlling the pressure of fuel injection air according to the acceleration state, it is possible to improve the acceleration characteristics of the engine.

[Brief explanation of drawings]

FIG. 1 is a drawing showing an example of an algorithm for controlling air pressure according to the acceleration state according to the present invention, and FIG.
An overall schematic diagram of an engine according to an embodiment of the present invention, FIG. 3 is a schematic sectional view of the air pressure regulator, FIG. 4 is a sectional view of the fuel metering device, and FIGS. 5, 6, and 7 are FIGS. 8A and 8B are sectional views showing the operating state of the fuel metering device, and are flowcharts showing examples of air pressure control. l... Engine, 2... Cylinder block, 3... Cylinder bore, 4... Piston, 5... Combustion chamber, 6...・・・・・・
Intake port, 7...Exhaust boat, 8...
...Intake valve, 9...Exhaust valve, 10...
...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, 3
0...Air pump, 31...Pneumatic regulator, 32...Akinimulator, 33.34.35.38...Air passage, 36.
... Controller, 39 ... Diaphragm, 40 ... Spring II material, 41 ...
...Solenoid, 42...Measuring chamber, 43
...Fuel inlet, 44...Fuel outlet, 4
5.46...Control valve 47...Fuel discharge port, 48...Fuel passage, 52...Adjustment body, 53...Cylinder Part, 54...
・Adjustment rod, 57...Linear motor, 59・
...Air chamber, 62...Solenoid valve, 6
2a...Solenoid for solenoid valve. (A) 8th floor plan (B)

Claims (1)

[Claims] A fuel metering chamber provided in a fuel supply system for storing a required amount of fuel; a regulating body for changing the volume of the metering chamber; and a fuel metering chamber for supplying the fuel stored in the metering chamber to the engine at a predetermined timing. a pressurizing means for applying air pressure to discharge the fuel from the metering chamber; an air pump for supplying pressurized air to the pressurizing means; and a pneumatic system provided between the air pump and the pressurizing means. 1. A fuel injection device for an engine, the fuel injection device having a pneumatic pressure regulator for adjusting air pressure, characterized in that the fuel injection device includes an air pressure control means for increasing the air pressure by a predetermined value when the engine accelerates.