JPH0281954A - Fuel atomizing method in fuel injection device - Google Patents

Abstract

PURPOSE:To improve atomizing efficiency of fuel by constituting a device supplying assist air by a reciprocating pump with a piston in an engine serving as the driving source. CONSTITUTION:A reciprocating pump 10 is driven by a piston 2 of an engine serving as the driving source. For instance, a cam 37 is provided in a crankshaft being associated with the piston 2, and the reciprocating pump 10 is driven through this cam 37, further its shape is formed in such a manner that the timing, the reciprocating pump 10 reaches one stroke end generating a maximum assist air pressure, is synchronized with the injection timing of fuel almost agreeing with the ignition timing the piston of the engine reaches the top dead center. Thus in the time of injecting fuel, a maximum pressure is generated in assist air, further its amount is in no relation to an engine load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of atomizing fuel in a fuel injection device.

(Prior Art and Problems to be Solved by the Invention) Conventionally, fuel injection devices have a configuration in which auxiliary air (hereinafter referred to as assist air) is introduced into the injection part in order to atomize the fuel injected from the fuel injection valve. For example, as shown in Japanese Unexamined Patent Publication No. 57-153961, one end is connected to a part of the intake pipe between an air flow meter and a throttle valve, and the other end is connected to a fuel discharge part of a fuel injection valve. A bypass passage connected nearby is provided to atomize the injected fuel using assist air introduced from the intake pipe, and such assist air is adjusted via an idle speed control valve during idle. An air assist device has been proposed.

However, with this fuel atomization method that uses negative pressure in the intake pipe, the amount of assist air decreases when the load is high because the differential pressure is low, and the fuel can only be obtained with a particle size of about 550 μm, making it difficult to achieve atomization. It had no drawbacks.

Further, as an atomization method that does not utilize intake pipe negative pressure, there is a method of supplying assist air using an electric pump such as a vane pump. Although this J:Una method compensates for the drawbacks associated with the method using negative pressure in the intake pipe as described above, it does not require the use of a large electric pump. proposed a configuration in which an on-off valve is provided in the assist air supply path and the opening timing of the on-off valve is synchronized with the timing of fuel injection to achieve efficient atomization with a small amount of assist air. ing.

However, such a configuration has the disadvantage of high cost because it is necessary to provide a control circuit for controlling the ff1la on/off valve and the valves therebetween.

(Means for Solving the Problems) In view of the drawbacks of the prior art described above, the fuel atomization method of the present invention provides a fuel atomization method for atomizing fuel by supplying assist air to the injection part of a fuel injection valve in a fuel injection device. This is a fuel atomization method in which assist air is supplied by a reciprocating pump whose driving source is a piston of one engine.

(Function) In the fuel atomization method of the present invention, a reciprocating pump is driven using a piston of one engine as a driving source. For example, a cam is provided on the crankshaft that interlocks with the piston, and the reciprocating pump is driven through the cam. The reciprocating pump that drives this cam has a fuel injection timing that almost coincides with the timing when the reciprocating pump reaches one stroke end and assist air pressure reaches its maximum, and the ignition timing when the engine piston reaches near top dead center. This allows the assist air to be at the maximum pressure during fuel injection, and the amount of assist air to be independent of the engine load.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

The figure shows an apparatus for actually carrying out the fuel atomization method according to an embodiment of the present invention. In the cylinder head 1 whose main parts are shown in FIG. 1, 2 is a piston.

3 is a piston rod connected to the piston 2, 4 is an intake pipe, 5 is an exhaust pipe, 6.7 is an engine valve on the intake and non-air side, respectively, and the lower end of the piston rod 3 is connected to a crankshaft (not shown). A fuel injection valve 8 is installed in the intake pipe 4 on the upstream side close to the engine valve 6 and faces the engine valve 6, and furthermore, a fuel injection valve 8 is installed at the outlet of the fuel from the fuel injection valve 8. An injection section 9 is formed for applying assist air to the fuel.

10 is a diaphragm type reciprocating pump that is attached to a fixed part as appropriate, and the diaphragm 1 is connected by bolts 11 to 11.
It has an upper body 13 and a lower body 14 which are integrally fastened together with the body 2 sandwiched therebetween. Upper body 1
3 is provided with an inlet 15 and an outlet 16 for assist air.

The suction port 15 communicates with the outside air via a conduit 17 and an air cleaner (not shown), while the discharge port 16 communicates with the outside air via a conduit 18.
It communicates with the injection section 9 via. Diaphragm 1
Upper seal L 2 is attached to the upper and lower parts of 2 via bolts 19 to 19.
0 and the lower shell 21 are fastened. lower shell 2
The upper end of a rod 22 is fixed to the lower surface of the lower body 14, and the lower end of the rod 22 protrudes outward from the lower body 14. A lower part 14a of the lower body 14 is formed into a cylindrical shape coaxial with the rod 22, and a guide cylinder 23 is press-fitted into the lower part 14a and guides the rod 22 so that it can be opened with a suitable rearance. In addition, the lower end of the rod 22 has an inner retainer 24a, an intermediate retainer 24a, and an intermediate retainer 24a.
A retainer member 24 consisting of a
ffi 24 d has a planar shape. A back spring 25 is interposed between the retainer member 24 and the lower surface of the lower part 14a of the lower body 14, and always urges the rod 2z downward via the retainer member 24. Note that the outer retape 24C of the retainer member 24 forms a receiving surface for the lower end of the back spring 25.

The interior of the body consisting of an upper body 13 and a lower body 14 is separated by the diaphragm 12 into a seven-way chamber 26 and a lower chamber 27.

The upper part of the upper chamber 26 communicates with a suction side chamber 30 and a discharge side chamber 31 via an inside valve 28 and an outside valve 29, each of which is a check valve.

The suction side chamber 3o and the discharge side chamber 31 are separated by a partition wall 13a formed integrally with the upper body 13, and communicate with the suction port 15 and the discharge port 16, respectively. The in-side valve 28 and the out-side valve 29 have the same configuration except that they are attached to the upper body 13 in different directions, and are fixed to the valve seat 32 fixed to the upper body 13 and the center part of the valve seat 32, respectively. A support member 33 having a shaft portion 33a. Its shaft part 3
Coil spring 34 inserted through 3a. The coil spring 34 presses the valve seat 32 against the valve seat 3.
The valve body 35 has a valve body 35 that closes the communication holes 32a to 32a formed in the valve seat 32, and the communication holes 32a to 32a of the valve seat 32 can be opened and closed by the valve body 35 based on the differential pressure between the upper and lower sides.

A camshaft 36 drives both or one of the engine valves 6 and 7, and is rotationally driven by the above-mentioned crankshaft via a belt or chain (not shown). The reciprocating pump 10 is located above the camshaft 36, and the lower surface 24d of the retainer member 24 of the reciprocating pump 10 is pressed into contact with the camshaft 36 by the biasing force of the back spring 25. 37 is fixed. The cam 37 is bilaterally symmetrical as shown in FIG. 2, and has a convex cam surface portion 37a.
and a substantially circular cam surface portion 37b. The camshaft 36 is rotationally driven by the crankshaft in the direction of the arrow in FIG.
The rod 22 is pushed upward as the contact point with the circular cam surface portion 37b rotates beyond the continuous point A between the cam surface portion 37b and the convex cam surface portion 37a. When the rod 22 reaches the center point B of the convex cam surface portion 37a, the rod 22 is at the maximum position, and when it passes the center point B, the rod 22 descends 1, and the contact point is the cam surface portion 37a.
At the other continuous point C between C and the convex cam surface portion 37a, the rod 22 reaches its lowest position and remains at that height until it reaches the other continuous point again. Here, the angle at which the cam 37 is attached to the camshaft 36 is set so that the timing at which the contact point reaches the center point B and the timing at which the piston 2 reaches the top dead center almost coincide.

Next, the operation of the above embodiment will be explained.

As the piston 2 of the engine moves from the top dead center position to the bottom dead center position shown in FIG. The contact point moves from the center point B toward the continuous point C. As a result, the rod 22 gradually descends from its lowest raised position, creating a negative pressure inside the upper chamber 26, and the differential pressure between the loose chamber 26 and the suction side chamber 30 causes the valve body 35 of the inner valve 28 to coil. The air moves downward against the spring 34, the flow holes 32a to 32a open, and the air guided into the suction side chamber 30 flows into the upper chamber 26. On the other hand, the valve body 35 of the outdoor side valve 29 is pressed against the communication holes 32a to 32a due to the above-mentioned pressure difference, and is maintained in a closed state.

When the crimping point reaches the continuous point C, the rod 22 becomes the lowest position, the camshaft 36 rotates further, the crimping point reaches the continuous point A, and as it moves toward the center point B, the rod 22
2 goes up W. As the rod 22 rises, the air flowing into the upper chamber 26 is gradually pressurized, and the differential pressure between the Arapara chamber 26 and the discharge side chamber 31 causes the valve body 35 of the outer valve 29 to resist the coil spring 34. Then, the flow holes 32a to 32a open and the air in the upper chamber 26 is sent out into the discharge side chamber 31.

At this time, the valve body 35 of the in-side valve 28 is pressed against the communication holes 32a to 32a by the pressure difference, and the valve body 35 is kept closed. The air sent into the discharge side chamber 31 is further discharged through the discharge port 16.
The air is then discharged to the injection section 9 as anth 1-air through the conduit 18, and when the crimping point reaches the center point B, the pressure of the discharge 1 becomes maximum. The timing of tie reaching center point 13, mink and piston 2 reaching top dead center are almost the same and J3
Since this timing almost coincides with the fuel ignition timing and also with the fuel injection timing from the fuel injection valve 8, the maximum pressure of assist air is obtained at the fuel injection timing. collides with the injected fuel from the fuel injection valve 8 at the maximum pressure in the injection part 9, and the fuel can be atomized well.

(Effects of the Invention) Since the fuel atomization method of the present invention supplies assist air using a reciprocating pump driven by the piston of the engine, the fuel can be atomized in all operating ranges regardless of the engine load. be able to.

In addition, there is no need to install an electromagnetic on-off valve or a control circuit to control the valves, which is required when using an electric motor, so fuel can be atomized at low cost. This makes it possible to easily match the timing at which the discharge pressure of the reciprocating pump reaches its maximum with the fuel injection timing, increasing fuel atomization efficiency and further improving fuel atomization. have

[Brief explanation of the drawing]

FIG. 1 is an overall view showing an apparatus for carrying out a fuel nization method according to an embodiment of the present invention, and FIG. 2 is an ll-4 diagram of FIG. 1.
This is a line arrow symbol. 8...Fuel injection valve 9...Injection part 10...Reciprocating pump

Claims (1)

[Claims] A fuel atomization method for atomizing fuel by supplying assist air to the injection part of a fuel injection valve in a fuel injection device, the assist air being supplied by a reciprocating pump driven by an engine piston. A fuel atomization method in a fuel injection device, characterized in that: