JPH10141173A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dead volume to prevent vapor lock by providing plural fuel injection valves adapted to open and close according to the pressure of fule in a fuel pipe to inject fuel from the other end part in a designated timing in the respective designated positions of the fuel pipe. SOLUTION: A fuel injection device 1 comprises a solenoid valve part 2 for supplying fuel, a fuel pipe 3 and plural poppet valves 4 which are fuel injection valves connected to the fuel pipe 3 for injecting fuel. A designated number of poppet valves are arranged in designated positions according to the type and the cylinder number of an engine. The poppet valve 4 has one end part 41 connected to the fuel pipe 3 and the other end part 42 set on the fuel injection side. When pressure in the fuel pipe 3 exceeds a designated alue, the poppet valves 4 inject fuel. Thus, the dead volume can be reduced so as to decrease the generation amount of vapor lock.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for supplying fuel to an internal combustion engine, and more particularly to a fuel injection device for injecting fuel into an intake pipe or a cylinder of an engine to create an air-fuel mixture. Things.

[0002]

2. Description of the Related Art In a system for producing an air-fuel mixture for driving an engine, there is a system in which a fuel injection valve is provided in an intake pipe to inject a predetermined amount of fuel to produce an air-fuel mixture. This fuel injection system has a higher degree of freedom in adjusting the mixing ratio than the conventional carburetor (carburetor) system, and can improve the performance of the engine.

As such a conventional technique, for example, there is a technique described in JP-A-63-1758. The details are described in the publication, but will be briefly described below.

FIG. 4 is a schematic configuration diagram of a fuel injection device 100 according to the prior art described in JP-A-63-1758.

[0005] In a fuel injection device 100, a solenoid type fuel distribution device (fuel injector) 101 receives fuel at a desired pressure and meters and supplies fuel to a plurality of fuel pipes (fuel discharge lines) 102. Each fuel pipe 102 sends fuel to a fuel injection valve (injection nozzle (poppet valve)) 103, and each fuel injection valve 103 is connected to each cylinder internal combustion engine 10.
The fuel is injected toward the fourth intake valve section 105.

[0006] More specifically, first, the fuel distribution device 10
In 1, a fuel adjusted to a desired pressure from a fuel supply source (not shown) is taken into a solenoid valve (not shown) provided inside the apparatus.

[0007] The solenoid coil is controlled by a conventional technique to supply fuel by energizing it with a pulse width modulation current. That is, when the pulse width is increased, the valve is opened for a long time to increase the amount of fuel supplied to the fuel pipe 102, and the amount of supplied fuel is adjusted by the pulse width.

Then, fuel is injected from a fuel injection valve 103 toward an intake valve section 105 of a cylinder internal combustion engine 104 in accordance with the fuel supplied into the fuel pipe 102.

[0009]

However, in the case of the above-mentioned prior art, a predetermined number of fuel pipes 102 are required in accordance with the number of cylinders. The total volume up to the tip (injection section) of the injection valve 103 tends to increase in accordance with the number of fuel pipes 102.

By the way, as the dead volume increases, vapor (fuel vapor) tends to be generated in proportion thereto. Problems caused by this vapor include, for example, a vapor lock (steam clogging), a decrease in vapor removability, and a damper effect of vapor accumulated in the fuel pipe 102, so that the pressure in the fuel pipe 102 does not increase. Injected fuel may decrease, or the proportion of vapor in the injected fuel may increase, resulting in a shortage of the actual fuel supply for the required fuel and poor engine startability. Evil is considered.

Therefore, as one of the measures to prevent the occurrence of such a problem, there is a technical demand to make the dead volume as small as possible.

Further, since the fuel tube 102 uses a resin tube, its rigidity is low, and it tends to take a long time before the pressure inside the fuel tube 102 increases.

Accordingly, the longer the time until the pressure in the fuel pipe 102 rises (and the time until the pressure falls), the longer the operation time is when the engine is operated at a high frequency and a long injection time (when the engine is at a high speed and a high load). In such a case, during the period from the previous injection to the next injection (pause time), the phenomenon that the next injection starts without the pressure in the fuel injection valve 103 (the fuel pipe 102) dropping to a predetermined pressure. It is easy to happen.

That is, the fuel injection valve 103 (the fuel pipe 10
The change in pressure in 2) becomes the overlap time, and the actual injection time is reduced with respect to the injection command time (see FIG. 2B). As a result, the injection amount characteristics become unstable.

Therefore, as one of the measures to reduce the overlap time in order to improve the injection quantity characteristics,
There is a technical demand to increase the rigidity of the fuel pipe 102.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to reduce the number of parts, improve the vapor removal property, and improve the injection amount characteristic. An object of the present invention is to provide a fuel injection device that is stable and has excellent quality.

[0017]

In order to achieve the above object, according to the present invention, a fuel pressure regulated by pressure regulating means is opened and closed at a predetermined timing to intermittently generate a pressure wave. And a fuel pipe for guiding fuel supplied by the solenoid valve. One end of the fuel pipe is connected to the fuel pipe, and is opened according to the pressure of the fuel in the fuel pipe. A plurality of valves and a plurality of fuel injection valves for closing and injecting fuel from the other end at a predetermined timing are provided at predetermined positions of the fuel pipe.

Therefore, since fuel is supplied to a plurality of fuel injection valves by one fuel pipe, the dead volume (total volume from the valve portion of the solenoid valve to the valve portion of each fuel injection valve) can be reduced. Becomes

Preferably, the fuel pipe is resin-molded integrally with at least a housing accommodating the solenoid valve.

Therefore, the number of parts can be reduced, and the wall thickness of the fuel pipe can be freely set.

It is preferable that the threshold value of the pressure for opening and closing the fuel injection valve is adjusted according to the distance from the solenoid valve.

Therefore, each fuel injection valve having a different distance from the valve portion of the solenoid valve injects fuel with an appropriate injection amount.

[0023]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

FIG. 1 is a schematic sectional view of a fuel injection device according to an embodiment of the present invention. FIG. 1A is a schematic configuration diagram of the entire fuel injection device, and FIG. FIG.

The fuel injection device 1 includes an electromagnetic valve section 2 for supplying fuel, a fuel pipe 3 for guiding fuel supplied by the electromagnetic valve section 2, and a plurality of fuel pipes connected to the fuel pipe 3 for injecting fuel. And a poppet valve 4 as a fuel injection valve.

In the solenoid valve section 2, fuel supplied from a fuel tank (not shown) is taken into the inside of the apparatus through a fuel inlet pipe 21, and the fuel is regulated to a constant pressure by a pressure regulator 22 as a pressure regulating means. The supplied fuel is supplied into the solenoid valve 23. The fuel not supplied is returned from the fuel return pipe 24 to the fuel tank. Further, the pressure regulator 22, the solenoid valve 23 and the like are incorporated in the housing 25.

The fuel pipe 3 is connected to the housing 25 of the solenoid valve 2.
Since the wall 31 is formed integrally with the resin, the wall thickness of the wall 31 can be freely designed, and the wall thickness can be determined so as to obtain a predetermined rigidity.

A predetermined number of poppet valves 4 are arranged at predetermined positions in the one fuel pipe 3 according to the type of engine and the number of cylinders.

The poppet valve 4 will be described more specifically with reference to FIG.
Has one end 41 connected to the fuel pipe 3 and the other end 42 on the fuel injection side. The poppet valve 4 has a concave groove 43 on the outer diameter side so as to be fitted into a mounting hole provided in an intake section of an engine cylinder (not shown).
Is formed, and the O-ring 44 is fitted into the concave groove 43 to form a sealed state with the mounting hole.

The poppet valve 4 has a cylindrical valve seat 45 coaxially connected to an inner diameter portion on the fuel injection side, and the valve seat 45 has a flow path 45a having an open inner diameter portion.
Is formed and fuel is supplied. A seat surface 45b is formed at an end of the flow passage 45a, and a steel ball 46 serving as a valve body is provided so as to be able to freely contact and separate from the seat surface 45b.

The steel ball 46 is connected to the valve stem 47 and the valve stem 4
7 is provided with a coil spring 48 as urging means. The urging force of the coil spring 48 urges the valve stem to bring the steel ball 46 into contact with the seat surface 45b. When the pressure of the fuel supplied by the fuel pipe 3 is lower than a predetermined value, the poppet valve 4 is closed so as not to perform the fuel injection. Then, when the pressure of the fuel supplied by the fuel pipe 3 becomes higher than a predetermined value, the steel ball 46 separates from the seat surface 45b against the urging force of the coil spring 48, and the fuel is injected with the valve open.

Hereinafter, each operation of the fuel injection device 1 configured as described above will be described.

First, the fuel taken into the inside of the apparatus from the fuel inlet pipe 21 is adjusted to a constant pressure by the pressure regulator 22, and the fuel whose pressure has been adjusted is supplied into the solenoid valve 23. Then, the required injection amount according to the state of the engine is determined by a control unit (not shown), and the solenoid valve 23 is opened and closed according to the support of the control unit, so that the intermittent pressure is applied to the fuel pipe 3. The fuel accompanied by the waves is supplied and pumped to each poppet valve 4.

Then, as described above, when the pressure in the fuel pipe 3 becomes higher than a predetermined value, the poppet valve 4 injects fuel and injects fuel until the pressure in the fuel pipe 3 becomes lower than the predetermined value. Keep doing. Note that each poppet valve 4 has a different distance from the valve portion of the solenoid valve 23, but by setting a threshold value of the pressure for opening and closing the valve in accordance with each distance, the respective poppet valves 4 can be appropriately adjusted. Injection can be performed with an appropriate injection amount.

As described above, in the fuel injection device 1 according to the embodiment of the present invention, a predetermined number of poppet valves 4 are arranged at predetermined positions with respect to one fuel pipe 3. It is possible to reduce the dead volume (total volume from the valve portion of the solenoid valve to the valve portion of each poppet valve) as compared with a case where a fuel pipe is provided for each of a plurality of poppet valves as in the related art. Therefore, the amount of generated vapor decreases accordingly. (Because the amount of vapor generated during operation is proportional to the amount of fuel in the fuel pipe 3,
The larger the dead volume, the greater the amount of vapor generated. Therefore, the vapor lock (steam clogging) is less likely to occur, and the vapor removability is improved, and the fuel injected by the poppet valve 4 is stabilized, and the fuel is supplied in an appropriate amount with respect to the required fuel. Sex is normal and the engine speed is always normal.

The effect obtained by setting the rigidity of the wall 31 of the fuel pipe 3 larger than the rigidity of the fuel pipe of the prior art to set a predetermined rigidity will be described.

FIG. 2 is a graph 1 for evaluating the performance of the fuel injection device.
FIG. 3 is a graph showing a dynamic range characteristic graph (fuel injection characteristic) as one index, and FIG. 3 shows the injection time of a poppet valve that responds to opening / closing of a solenoid valve performed by the support of a control unit. FIG. 3 (a) is a comparison chart diagram of the present embodiment (FIG. 3 (b)).

FIG. 7 is a brief description of the dynamic range characteristic graph.

First, the measuring method is such that the pulse period is 10 ms (1
00 Hz) and a duty ratio of 0 to 100% (0 to 10 m).
Sweep until s), and measure each injection amount.

When the duty ratio is 25% (2.5 m
s) and a straight line (y = tx + a) connecting the injection amount in the case of 75% (7.5 ms) is a straight line of the basic injection characteristic. Then, the duty ratio is changed, and each injection amount is measured. Then, as shown in the figure, there are unstable portions that deviate from the straight line of the basic injection characteristics with short pulses and long pulses. That is, the points t1 and t2 deviate from the threshold, and the threshold deviates from the straight line of the basic injection characteristic by 5%. The region from t1 to t2 is defined as a stable region. Note that t0 is a point where the injection amount is considered to be 0 from the straight line of the basic injection characteristic, and corresponds to a response delay of the solenoid.

Thus, the following dimensionless expression is obtained.

D / R = (t2−t0) / (t1−t0) The higher the value obtained from this equation, the better the dynamic range characteristic. If the duty ratio during idling becomes shorter than the point t1, the engine speed becomes unstable, and the point t2 becomes 100% (10%).
ms), it is possible to cope with a high rotation and high load (high output) engine.

By increasing the rigidity of the wall 31 of the fuel pipe 3, the speed at which the pressure in the fuel pipe 3 rises and falls increases, and as shown in FIG. 3, the response of the poppet valve 4 improves. The time from opening to closing and from closing to opening of the poppet valve 4 is shortened, that is, the slope of the straight line on the graph becomes steep.

Therefore, the drive time until the overlap is extended, that is, t2 is increased by the difference in the change in the slope of the straight line on the graph in FIG. 3 (t2 is substantially the overlap start point). Also,
Similarly, t1 approaches t0 by the difference between the changes in the slope of the straight line. Therefore, it can be seen that D / R is increased by increasing the rigidity, and the dynamic range (fuel injection characteristics) is improved.

[0045]

According to the present invention, since a plurality of fuel injection valves are provided at each predetermined position of the fuel pipe, fuel is supplied to the plurality of fuel injection valves by one fuel pipe, so that the dead volume is reduced. It is possible to reduce the amount of vapor generated, and it is difficult for vapor lock to occur,
Vapor removal is also improved. Therefore, the fuel injected by the fuel injector is stabilized, and the fuel can be supplied in an appropriate amount with respect to the required fuel, so that the startability of the engine is performed normally, and the engine speed is always normal, Quality is improved.

Further, by molding the fuel pipe integrally with at least the housing accommodating the solenoid valve, the number of parts can be reduced, and the wall thickness of the fuel pipe can be freely set, thereby increasing rigidity. By increasing the value, the fuel injection characteristics can be improved, and the quality can be further improved.

By adjusting the pressure thresholds for opening and closing the fuel injection valve in accordance with the distance from the solenoid valve, each fuel injection valve having a different distance from the valve portion of the solenoid valve can be used. , It is possible to inject fuel with an appropriate injection amount.

[Brief description of the drawings]

FIG. 1 is a schematic configuration sectional view of a fuel injection device according to an embodiment of the present invention.

FIG. 2 is a dynamic range characteristic graph.

FIG. 3 is a comparison chart showing the reaction injection time of the poppet valve with respect to the solenoid valve in the conventional art (a) and the embodiment (b).

FIG. 4 is a schematic configuration diagram of a fuel injection device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection device 2 Solenoid valve part 22 Pressure regulator 23 Solenoid valve 25 Housing 3 Fuel pipe 31 Wall (of fuel pipe) 4 Poppet valve (fuel injection valve) 41 One end 42 The other end

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 55/00 F02M 63/06 63/06 51/02 R

Claims (3)

[Claims] 1. An electromagnetic valve for opening and closing a fuel pressure regulated by a pressure regulating means at a predetermined timing to supply fuel accompanied by intermittent pressure waves, and a fuel supplied by the electromagnetic valve. One end is connected to the fuel pipe, and the valve is opened and closed according to the pressure of the fuel in the fuel pipe, and fuel is injected at a predetermined timing from the other end. A plurality of fuel injection valves provided at predetermined positions of the fuel pipe. 2. The fuel injection device according to claim 1, wherein the fuel pipe is resin-molded integrally with at least a housing accommodating the solenoid valve. 3. The fuel injection valve according to claim 1, wherein a threshold value of a pressure for opening and closing the fuel injection valve is adjusted according to a distance from the solenoid valve. Fuel injector.