JPS58204967A - Cylinder injection engine - Google Patents

Abstract

PURPOSE:To separate the discharge of fuel by an injection valve from the injection of the fuel toward an ignition plug, and promote the low pressure of a fuel system, low cost and electronic control as well as to make the bedding combustion performable. CONSTITUTION:Fuel injection out of a fuel injection valve 6 takes place at the timing when pressure inside a cylinder at the initial stage of a suction stroke or a compression stroke is almost approximate to atmospheric pressure, and after the elapse of the specified time (at the latter period of a compression stroke), the fuel stored inside a fuel holding part 24 is vibrated by an ultrasonic vibrator 7, atomizing the fuel and injecting it toward an ignition plug inside a combustion chamber, and the fuel is ignited by the ignition plug whereby the bedding combustion is promoted in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direct injection engine, and in particular to a spark-assisted direct injection engine that injects fuel directly into the combustion chamber of an internal combustion engine and ignites it with a spark plug, which is suitable for stratified charge combustion. Regarding the engine.

In conventional spark-assisted direct injection engines, in order to achieve stratified charge combustion, the injection timing by the fuel injector is set to the latter half of the compression stroke (25 to 45 degrees B).

TDC). Therefore, it is necessary to inject fuel into the combustion chamber, which has a high compression pressure. Therefore, this type of direct injection engine requires a high-pressure injection valve (2
5 to 100 phrases/c1n").

However, in the above-mentioned conventional direct injection engine, it is necessary to use a high-pressure fuel injection valve, so fuel injection cannot be controlled easily, and the cost of the fuel supply system must be reduced and electronic control There was a problem that it was extremely difficult to convert.

An object of the present invention is to provide a direct injection engine that enables stratified combustion by lowering the pressure and cost of the fuel supply system, and furthermore, by implementing complete external electronic control. In order to achieve this, the direct injection engine according to the present invention uses a low-pressure type fuel injection valve, a fuel holding portion is provided at the tip of the injection valve, and an ultrasonic wave vibrating the fuel holding portion is provided near the injection valve. A vibrator is provided, and the fuel in the holding portion is atomized and injected by the vibrator.

According to the present invention, the discharge of fuel by the fuel injection valve and the injection of the discharged fuel toward the spark plug can be separated. Therefore, fuel injection from the fuel injector can be performed when the in-cylinder pressure at the intake level i or at the beginning of the compression stroke is close to atmospheric pressure, and after a predetermined time (for example, in the latter half of the compression stroke), the fuel can be injected into the fuel holding part. Stratified combustion can be achieved by vibrating the fuel stored in the combustion chamber with an ultrasonic vibrator, granulating the fuel, injecting it toward the spark plug in the combustion chamber, and igniting it with the spark plug.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a direct injection engine according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of the structure of a direct injection engine according to this embodiment. As shown in this figure, the engine is provided with a cavity 2 in the head portion of a piston 1. Furthermore, a fuel injection device 4 and a spark plug 5 are installed within the combustion chamber 3.

In particular, in this embodiment, the fuel injection device 4 is configured with a fuel injection valve 6 and an ultrasonic vibrator 7, and a dome-shaped fuel is provided at the tip of the fuel injection valve 6 to store the injected fuel at one point. A mask 8 as a holding part is attached.

Further, this engine has an injector drive circuit 9 connected to the fuel injector 6 and an ultrasonic oscillator 10 connected to the ultrasonic vibrator 7, and further includes an ignition oscillator 10 that sends an ignition signal to the spark plug 5. It has a device 11. These injection valve drive circuit 9, ultrasonic oscillator 10, and ignition device 11 are connected to a microcomputer 12, and act on the injection valve 6 and the vibrator 7 at the injection timing calculated or mapped by the microcomputer 12. The fuel is to be ignited at the appropriate time.

In such an engine, the specific structure of the fuel injection system @4 is shown in FIG. That is, the fuel injection valve 6 constituting the device 4 is a low-pressure solenoid valve, and a magnetic coil 15 is wound around the yoke 14 inside the casing 13.
and a plunger 16 that is actuated thereby. Further, a small-diameter nozzle portion 17 is provided at the tip of the casing 13, and a poppet-type valve body 18 that opens and closes is attached to the tip of the nozzle portion 17. This valve body 18 is connected to the plunger 16 and m-dol 19.
The opening and closing operations are performed by the reciprocating movement of the plunger 16.

In this case, as shown in the figure, when the plunger 16 moves downward, the valve body 18 protrudes from the tip of the nozzle portion 17, allowing fuel to be discharged from the fuel chamber 20 formed within the nozzle portion 17. And usually the needle 19
The valve is closed by a spring 21 that urges the valve upward. Further, fuel is supplied to the fuel chamber 20 through a fuel inlet provided at the head of the casing 13,
This is done through a fuel passage 34 bored through the center of the plunger 16 and needle 19.

The above-mentioned ultrasonic vibrator 7 is attached to the outer periphery of the nozzle portion 17 of such a fuel injection valve 6. This vibrator 7 is attached to the nozzle portion 17 with a predetermined gap therebetween, and is held by vibrator valve plates 22 located at the upper and lower ends thereof.

That is, it is fixed by a bolt 23 that passes through the vibrator 7 from the lower vibrator valve flap 22 and is screwed onto the upper vibrator valve flap 22. Further, a dome-shaped mask 8 formed to cover the tip of the nozzle portion 17 is integrally formed on the lower vibrator valve valve 22 . Therefore, the fuel injected from the fuel injection valve 6 enters the cavity 24 of the mask 8.
It is temporarily housed inside. The mask 8 has injection holes 25 formed therein. The injection holes 25 are provided in a number corresponding to the number of spark plugs 5, and open toward the spark plugs 5 inside the combustion chamber 3.

The injection device 4 comprising such a fuel injection valve 6 and an ultrasonic vibrator 7 is attached to the engine body 26, and this is done in the following manner. That is, the vibrator valve plate 22 to which the vibrator 7 is attached is attached to the outer circumferential surface of the nozzle part 17 of the injection valve 6 with a predetermined gap, and the step between the casing 13 and the nozzle part 17 is provided with a vibration-proof structure. They abut through the material 27. A seal portion 28 is provided on the tip surface of the nozzle portion 17.
It is brought into pressure contact with the inner wall surface of the mask 8 via.

In this state, insert the mask 8 into the combustion chamber 3 into the engine body 26, and insert the casing 13 of the injection valve 6.
It is fixed to the main body 26 via a threaded portion 29 formed on the outer periphery of the fc. The mask 8 is placed in the combustion chamber 3.
Attach the lower vibrator valve valve 22 so that only the chisel protrudes.
A seal portion 30 is provided between the front end surface of the engine body 26 and the engine body 26 to seal the combustion chamber 3.

In the fuel injection device 4, an input terminal 31 to the electromagnetic coil 15 and a positive terminal 32 connected to the ultrasonic vibrator 7 are led to the outside of the engine body 2G, and this is connected to the injection valve drive circuit 9 described above. and an ultrasonic oscillator 10, respectively.

The direct injection engine thus constructed operates as follows. Fuel is supplied to the fuel injection valve 6 by a fuel port 33, and this fuel is sent to the fuel chamber 20 via a fuel passage 34 in the plunger 16 and needle 19. From this state, when a valve opening signal is input to the input terminal 31 by the injection valve starting circuit 9, the plunger 16 is moved downward by the coil 15, and the valve body 18 is also moved downward together with the needle 19, and the valve is opened. As a result, the fuel in the fuel chamber 20 is discharged, and the empty space 2 in the mask 8 is discharged.
It is temporarily held within 4. Thereafter, when a valve closing signal is input, the plunger 16 is moved upward by the spring 21 and the valve is closed. Therefore, the space 24 in the mask 8 temporarily stores the metered amount of fuel corresponding to the valve opening time.

In this way, after the fuel is injected into the cavity 24, after a certain period of time, the ultrasonic oscillator 10 sends the positive terminal 32 to the positive terminal 32.
When a signal is input to the ultrasonic transducer 7, the ultrasonic transducer 7 vibrates. When this ultrasonic transducer 7 vibrates, the lower transducer valve 22
Since the seal portions 28 and 30 between the nozzle portion 17 and the engine body 26 are not fixed points (nodes) that do not vibrate, the tip of the mask 8 becomes a free end and vibrates violently.

Due to this vibration, the fuel in the cavity 24 is atomized and discharged from the injection hole 25. Since the injection hole 25 is oriented toward the spark plug 5 as described above, the atomized fuel is concentrated near the spark plug 5.

Then, by sending a signal from the ignition device 11,
The spark plug 5 ignites the fuel.

In this way, the direct injection engine distinguishes between discharging measured fuel into the combustion chamber (9) 3 and injecting the discharged fuel in an atomized state toward the spark plug 5. In particular, since the atomization of the fuel is carried out by the action of the ultrasonic vibrator 7, combined with the effect of the cavity 2 of the piston 1, the flammable air-fuel mixture concentrates near the spark plug 5, achieving stratified combustion. This enables combustion with a thin overall air-fuel ratio.

Next, the operating timing of the fuel injection valve 6, ultrasonic vibrator 7, and spark plug 5 in the engine will be explained based on FIG. 3. This figure shows the relationship between the cylinder pressure P of the combustion chamber 3, the operating timing A1 of the fuel injection valve 6, the operating timing B of the ultrasonic vibrator 7, and the operating timing C of the spark plug 5. As shown in FIGS. 3(1) and 3(2), the injection valve 6 is opened at the beginning of the intake stroke or compression stroke, and fuel is injected into the cavity 24 of the mask 8. After that, a predetermined time t
Then, the ultrasonic vibrator 7 is vibrated, the fuel is atomized and supplied to the combustion chamber 3 from the injection hole 25, and the vibration is stopped. Then, the ignition ring 5 ignites the flame 10 to cause an explosion. In this way, the injection valve 6 only needs to inject fuel when the in-cylinder pressure P at the beginning of the intake stroke or compression stroke is close to atmospheric pressure or at the same time, unlike the conventional high-pressure type that injects fuel at the latter half of the compression stroke. This eliminates the need for an injection device and enables injection at low pressure (for example, 2 to 3 kg/cm'').

In this case, since the valve body 18 of the fuel injection valve 6 is a poppet-type valve, unlike a bottle-type injection valve, it cannot open even if combustion pressure acts on the tip of the needle 19 during the compression or explosion stroke. This makes it ideal for reducing pressure in direct injection valves.

As described above, in the direct injection engine according to this embodiment, the fuel injection valve 6 is a low-pressure type valve, and the fuel to be injected is atomized by the ultrasonic vibrator 7 and injected toward the spark plug 5. As a result, stratified combustion can be achieved and the cost of the fuel supply system can be significantly reduced, and furthermore, the injection system can be completely electronically controlled and the cost of the electronic control device can be reduced.

Fig. 3 f31, (41 shows an example in which the operating timing of the ultrasonic transducer 7 is changed (11). Fig. 3 (3) shows that the transducer 7f is activated during or before the opening period of the injection valve 6. Let it vibrate,
It is designed to ignite after the vibrations stop.

Further, in FIG. 4 (4), the vibrator 7 is vibrated during or after the injection valve 6 is opened and closed, and the vibration is stopped after the spark plug 5 is ignited. In this case, the ignition process and initial combustion are promoted due to the combustion promoting effect unique to ultrasonic waves.

Next, the ultrasonic transducer 7 in the above embodiment is controlled as follows. That is, the basic characteristics of the ultrasonic transducer 7 are shown in FIG.
) indicates the amplitude characteristics. As shown in the figure, the gain of the vibrator 7 is maximum at a certain frequency W (strong oscillation frequency),
The processing capacity of fuel atomization is maximized. Therefore, in this embodiment, this strong vibration frequency W1 is used. ．． are doing.

In addition, since the amplitude changes depending on the input power (wattage) to the camera element 7 (Fig. 4 (2)), in this example, the processing capacity when the fuel amount increases or decreases, and the amplitude of the spray characteristics That is, (12) control is performed by changing the wattage.

The wattage is controlled by changing the current value supplied to the ultrasonic oscillator 10 described above. Specifically, as shown in Figure 5 (1), the relationship between the amount of injected fuel and the required amplitude of the oscillator 7 is a straight line with respect to the amount of fuel from the viewpoint of processing capacity and spray characteristics. It is desirable to be in a relationship. Therefore, control is performed so that the wattage, that is, the current value, is changed with respect to the fuel amount as shown in (2) of the same figure. Furthermore, as shown in FIG. 6, it is possible to change the frequency without controlling the wattage so that the strong oscillation frequency W is reached at the maximum fuel amount.

It goes without saying that the frequency and amplitude may be constant regardless of the amount of fuel.

FIG. 7 shows the results of an experiment to determine the fuel efficiency using the direct injection engine configured as described above.

In this experiment, 100% methanol was used as fuel. In this figure, A shows the characteristics of a conventional in-cylinder injection system, that is, injecting and igniting using a high-pressure injection device in the latter half of the compression stroke, and (13) B shows the characteristics of the fuel efficiency rate according to this example. . As is clear from this figure, it can be seen that by atomizing the particles using the ultrasonic vibrator 7 and controlling the spray characteristics, a significant reduction in lean combustion and fuel efficiency can be achieved.

Next, modified examples of the fuel holding portion of the direct injection engine according to the present invention are shown in FIGS. 8 and 9. In FIG. 8, a mask as a fuel retaining portion formed on the lower vibrator valve valve 22 is constituted by a dome 35 made of a porous material, and the injection hole 2
5 is omitted. In this embodiment, the injected fuel is held within the cavity 24 and the holes of the multi-hole dome 35,
The fuel is atomized by the subsequent vibration of the ultrasonic vibrator 7 and dispersed within the combustion chamber 3. Further, in FIG. 9, the fuel holding portion is constructed by a cylinder 36. In this embodiment, the injected fuel collides with the inner wall of the cylinder 36, and even after this collision, it is reflected by the wall and collides with the opposing wall again. The fuel is retained within the cylinder 36 only during the repetition of this operation. After this period has elapsed, the fuel is atomized and dispersed into the combustion chamber 3 from the tip of the cylinder 36.

(14) FIG. 10 shows another embodiment of the present invention. In this system, a pressure transducer 38 is installed in the middle of the fuel pipe 37 of the fuel injection valve 6, and changes in fuel pressure are detected so that the opening timing of the injection valve 6 can be accurately determined. This detected valve opening signal is input to the microcomputer 12 and is used as a feedback signal for accurately controlling the opening timing of the injection valve 60 in a closed loop. Alternatively, the valve opening timing detected by the pressure transducer 38 can be used as a reference point for calculating the operating timing of the ultrasonic vibrator 7 and the spark plug 5 from the rotation speed and crank angle.

Furthermore, FIG. 11 shows another embodiment of the present invention.

This is applied to an engine provided with a sub-combustion chamber 39, in which the fuel injection device 4 and spark plug 5 are installed.

In this case, the injection holes 25 of the mask 8 are connected to the main combustion chamber 4.
It is pointed in the direction of 0. In this embodiment, when air flows into the sub-combustion chamber 39 during the compression stroke, the injection -f1
．． The fuel spray rides on this air flow and is carried toward the spark plug 5 (15) where it is ignited.

Furthermore, FIG. 12 shows still another embodiment, and this embodiment is an example of application to an engine equipped with one spark plug 5. This is to disperse fuel into a cavity 41 with a fuel injection device 4 and ignite it with a spark plug 5 to achieve stratified charge combustion.

As explained above, according to the direct injection engine according to the present invention, it is possible to lower the pressure of the fuel supply system, and also to atomize the fuel using the ultrasonic vibrator and fully control the spray characteristics. Complete electronic control of quantity control can be easily achieved, fuel efficiency can be reduced by 10-15%, and Group 1 combustion can be achieved with lean fuel.

[Brief explanation of the drawing]

Figure 1 shows the structure of the direct injection engine according to this embodiment, 1' is an oxidation surface diagram, and Figure 2 is! A cross-sectional view of the fuel injection device of the device, Figure 3 is a time chart of the fuel injection valve, ultrasonic vibrator and spark plug with respect to cylinder pressure, Figure 4 is a basic characteristic diagram of the ultrasonic vibrator, and Figure 5 is a diagram of the basic characteristics of the ultrasonic vibrator. Ultra (16) Characteristic diagram of the ultrasonic vibrator with respect to fuel quantity, Figure 6 is a frequency characteristic diagram of the ultrasonic vibrator with respect to fuel quantity, Figure 7 is a measurement graph of fuel consumption rate, and Figure 8 is deformation of the fuel holding part. FIG. 9 is a cross-sectional view of another modification of the fuel holding part; FIG. 10 is a cross-sectional view of another embodiment of the direct injection engine according to the present invention; FIG. 11 is a sectional view showing still another embodiment, and FIG. 12 is a sectional view showing the same embodiment. 3... Combustion chamber, 4... Fuel injection device, 5... Spark plug, 6... Fuel injection valve, 7... Ultrasonic vibrator,
Death: mask, 22: transducer valve, 25: injection hole, 26: engine (17) Figure (+) kite ゛ zuchi quantity //Yllessa i・f+ quantity /ha・ru,su 10th warm 110th 1z country

Claims (1)

[Scope of Claims] 1. In a direct injection engine in which a fuel injection valve and a spark plug are provided in a combustion chamber, and the fuel injection valve directly injects fuel to ignite a spark, the fuel injection valve is a low-pressure type valve, A cylinder comprising a fuel holding part at the tip of the injection valve, and an ultrasonic vibrator that vibrates the fuel holding part near the injection valve, and the vibrator atomizes the fuel in the holding part and injects it. Internal injection engine. 2. The direct injection engine according to claim 1, wherein the fuel holding portion is formed in a dome shape and is provided with an injection hole directed toward a spark plug. 3. The direct injection engine according to claim 1, wherein the fuel holding portion is made of a porous material and has a dome shape. 4. The fuel holding part has a cylindrical shape that opens into the combustion chamber.
2. The direct injection engine according to claim 1, wherein the fuel is retained at compression pressure. 5. The direct injection engine according to claim 1, wherein the fuel injection valve has a poppet type valve body.