JPH0799218B2 - Multi-point fuel injection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a multipoint fuel injection device used in an internal combustion engine.

[Conventional technology]

Generally, a multi-point type fuel injection device is disclosed, for example, in JP-A-55-1009.
As disclosed in Japanese Patent Publication No. 5 etc., a fuel injection valve is arranged for each intake pipe of each cylinder of the engine, and each fuel injection valve is
Connected to a branch pipe branched from the main fuel supply conduit,
With such a system configuration, a system is adopted in which the fuel pressure-fed from the fuel pump is supplied to each fuel injection valve via the fuel supply main conduit and the branch piping.

Further, the fuel injection valve used in this type of multi-point fuel injection device is composed of an electromagnetic injection valve, and introduces fuel into the main body from the top side of the injection valve main body, A so-called top feed type that guides to the fuel flow injection port side through a fuel supply passage (the fuel supply passage is arranged in the same direction as the movable valve operating direction) arranged in the fixed iron core portion of the injection valve Was the mainstream.

[Problems to be solved by the invention]

By the way, the environmental temperature surrounding the fuel system of an automobile engine is becoming higher and higher as the exhaust gas regulations of automobiles are strengthened and the aerodynamics is expanded. Especially in the summer when the outside air temperature exceeds 30 ° C, the ambient temperature near the fuel supply conduit including the fuel injection valve exceeds 100 ° C during restart (hot start) after high-speed running.
Most of the fuel in the fuel supply conduit immediately before restarting evaporates, (2) air bubbles are mixed in the new fuel that is pumped immediately after restarting, and (3) fuel injection valve at restarting. Since the amount of fuel supplied to the engine is extremely small in the amount of fuel required for start-up and idle operation, cooling by the fuel cannot be expected, and on the contrary, a phenomenon such as a part of the supplied fuel evaporates, and as a result, There was a problem that the restart time was long and malfunctions tended to occur when the engine stalled. In order to solve such a problem, in the past, for example, JP-A-58-41
As disclosed in Japanese Patent No. 259, the fuel supply conduit is inclined to separate and remove bubbles in the supplied fuel, and in some engine systems, the fuel pressure is temporarily increased only when the engine is restarted. In order to prevent the temperature rise (fuel pressure switching method) and the rise in the ambient temperature in the vicinity of the fuel injection valve and the fuel supply conduit, improvement measures such as a method of providing a cooling fan have been adopted.

However, among the above-mentioned conventional techniques, the method of removing the fuel by inclining the fuel supply conduit is mainly effective as a measure for improving the problem of the above (2), but (1),
As in the case of (3), it is not sufficient as a countermeasure when a large amount of fuel in the fuel supply conduit evaporates just before the engine is started, and any of the other methods causes complication of the engine system and cost increase. There was a tendency.

The present invention has been made in view of the above points, and it is an object of the present invention to improve the restartability of an engine at the time of a hot start and the engine after restart without complicating the engine system. An object of the present invention is to provide a multi-point fuel injection device capable of stabilizing the rotation speed.

[Means for solving problems]

The above object is achieved by taking the following means. The contents of the present invention will be described below with reference to the reference numerals of the embodiments of FIGS. 1 and 2.

That is, the present invention is a multi-point fuel injection device including a fuel injection valve 1 for each cylinder of an engine, in which each fuel injection valve 1 has a fuel inlet port provided on a side wall of the injection valve body.
It is composed of a bottom feed type fuel injection valve that injects fuel from 13 into the internal flow path of the injection valve body and injects surplus fuel that is not injected from a fuel outlet 14 provided on the side wall of the injection valve body. Fuel injected from each fuel injection valve 1
The fuel supply passage to be led to is constituted by a line 19 lined into one line, and each tubular holder portion 19 ′ accommodating and holding each fuel injection valve 1 in the middle of this line 19 The fuel inlet 13 of each fuel injection valve 1 faces the upstream side of the pipe line 19, and the fuel outlet port 14 faces the downstream side of the pipe line 19 to flow inside the injection valve body. 1 fuel flow A is formed, and between the outer circumference of the main body of each fuel injection valve 1 and the inner circumference of each holder portion 19 ', there is a circumferential flow passage structure along the outer circumference of the injection valve main body. Bypassing each fuel injection valve 1 and between the upstream side and downstream side pipes of the pipeline 19 before the fuel inlet 13 and the fuel outlet 14
Is formed immediately after the injection valve bypass passage 18 and the second fuel flow B flowing in the injection valve bypass passage 18 is formed.
As a result, a region C where the pressure becomes low is generated in the vicinity of the fuel outlet 14 of each fuel injection valve 1.

[Action]

According to the above configuration, when the fuel pump is activated by turning on the ignition key switch, new fuel pumped through the fuel pump is supplied with fuel and the fuel supply passage (pipe) 19 and a holder portion 19 for holding each injection valve in a series. It flows in ′. The flow of this fuel flows in each holder portion 19 'in each fuel injection valve 1
The first fuel flow A passing through the inside of the injection valve main body by the fuel inlet port 13 and the fuel outlet port 14 and the second fuel flow A bypassing the inside of the injection valve main body by the injection valve bypass passage 18 and extending along the outer periphery of the injection valve main body.
Fuel flow B of Of these, the second fuel flow B is
A region C in which the flow has a high flow velocity because it passes through the injection valve bypass passage 18 whose passage resistance is extremely smaller than that in the injection valve main body, and the flow lowers the pressure in the vicinity of the fuel outlet 14 behind the injection valve main body. (Fuel inlet 13 of injection valve 1,
In other words, a region (C) in which a negative pressure is relatively generated with respect to the thickness force of the surface receiving the fuel flow is generated.

Due to the existence of the low pressure region C, the fuel vapor (bubbles) staying in the fuel injection valve 1 at the time of hot restart is instantaneously drawn out of the injection valve main body, and the fuel inlet 13 and the fuel outlet 14 are also provided. The first fuel flow A passing through the inside of the main body of the fuel injection valve 1 via is also affected by the low pressure region C, and the flow velocity in the injection valve 1 is increased.

Therefore, due to the synergistic action of these first and second fuel flows, the fuel remaining in the pipe 19 and the fuel injection valve 1 before the restart is instantly swept away and new fuel is filled.

As a result, even if the engine is started immediately after the ignition key switch is turned on, proper fuel is circulated and fuel is injected. This fuel injection is performed by guiding a part of the first fuel flow A flowing from the fuel inlet 13 of the fuel injection valve 1 into the injection valve main body to the nozzle via the valve portion of the injection valve main body and the valve seat. Done.

Furthermore, the conduit 19 forming the fuel supply passage and the injection valve bypass passage 1
8 and the inside of the injection valve body are filled with appropriate fuel immediately after the ignition key is turned on as described above, so that each fuel injection valve 1 is cooled by the fuel passing through the inside and outside of the injection valve, so the cooling effect of the injection valve itself is also immediately effective. And effectively prevents bubbles from being generated inside the injection valve body even if the environmental temperature of the fuel system is high. Further, even when the bubbles are mixed from the outside, the bubbles can be drawn to the outside of the injection valve by utilizing the suction action of the low pressure region C. Due to each of the above effects, even during hot restart,
The restartability of the engine and the idle speed after restart can be stabilized.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a system configuration diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a partially omitted horizontal sectional view showing an internal structure of a fuel supply passage used in this embodiment, and FIG. 3 is a partially omitted vertical sectional view of this embodiment.

In FIG. 1, 1 is a fuel injection valve, 11 is an injection nozzle of the fuel injection valve, 19 is a pipe line for fuel supply (hereinafter referred to as a fuel supply conduit), and 19 'is a holder portion for holding the injection valve 1. The fuel supply conduit 19 and the holder portion 19 'constitute a fuel supply passage. 20 is a regulator.

The fuel injection valve 1 is a bottom feed type electromagnetic fuel injection valve (details will be described later), and a plurality of fuel injection valves 1 are arranged in the intake pipe for each cylinder of an engine (not shown). Further, the fuel supply conduit 19 is lined into one, and in the middle of this conduit 19, each holder portion 19 ′ accommodating and holding each fuel injection valve 1 is arranged in series via the conduit 19.

Here, the internal structure of the fuel injection valve 1 will be described with reference to FIG.

Reference numeral 2 is an assembly of the electromagnetic coil 2 ', 3 is a core around which the coil assembly 2 is wound, and 4 is a yoke forming a side wall of the injection valve main body 1. Inside the yoke 4, the coil assembly 2 and the core 3 are installed. It Reference numeral 5 denotes a plunger fitted in the center hole (flow passage) 4a of the yoke 4, a rod 6 is provided integrally with the plunger 5, and a ball (valve body) 7 is attached to the lowermost end of the rod 6. The plunger 5 constitutes a magnetic circuit together with the yoke 4 and the core 3, and when the electromagnetic coil 2'is energized, the plunger 5 moves by a predetermined stroke against the spring 8 and the rod 6 and the ball 7 are pulled up. Thus, the ball 7 is configured to open apart from the valve seat portion 12.

9 is a valve guide attached to the lower center of the yoke 4,
The valve seat part 12 is formed inside, and the valve seat part 12
Fuel injection nozzle with swirl orifice 10 on the downstream side of
11 is installed.

13 is a fuel inflow hole (fuel inlet) arranged in the yoke 4,
Reference numeral 14 denotes a fuel outlet hole (fuel outlet) arranged at a position of the yoke 4 opposite to the fuel inlet hole 13, and 15 denotes a space between an inner circumference of the yoke 4 and an outer circumference of the coil assembly 2. Fuel flow path. The fuel flow path 15 is a flow path provided in the center of the yoke 4.
Communicate with 4a. The fuel is a fuel inflow hole provided on the side wall of the yoke 4.
Fuel flows into the injection valve body via 13
It reaches the flow path 4a via 15. When the electromagnetic coil 2'is energized and controlled, a magnetic circuit is formed by the yoke 4, the core 3, the plunger 5, and the coil assembly 2, the plunger 5 is attracted to the core 3 side, and the ball 7 moves together with the plunger 5. An annular gap is formed between the seat portion 12 and the ball 7 to measure the fuel flowing from the internal flow path 4a. The measured fuel is injected and supplied to the engine after being swirled by a plurality of oblique holes (swirl orifices) 10 provided in the nozzle 11. In addition, a part of the remaining fuel that is not injected reaches the fuel outflow hole 14 directly along the outer peripheral surface of the coil assembly 2,
The other remaining fuel flows from between the inner periphery of the coil assembly 2 and the outer periphery of a part of the core 3 (coil winding location) to the coil assembly 2.
Is discharged to the fuel supply conduit 19 side through the outer periphery of the fuel outlet hole 14.

Reference numeral 16 is an annular cover for covering a part of the body of the yoke 4, and the cover 16 constitutes a side wall of the injection valve body together with the yoke 4, and has a hole 13 'corresponding to the inflow hole 13 on the yoke 4 side and an outflow hole 14. Corresponding holes 14 'are provided.

Each holder portion 19 'is formed in a rigid hollow cylindrical shape, and each injection valve 1 constituted by elements such as reference numerals 2 to 16 is housed and held inside with its center aligned. The valve guide 9 of the injection valve 1 is set in a hole 17 formed in the wall in a fitted state. In addition, a part of the side wall of the main body of the injection valve 1 (the cover 16
The outer diameter of the lower part of the yoke 4) is sufficiently smaller than the inner diameter of the holder part 19 'so that the outer peripheral surface of the side wall of the injection valve 1 and the inner peripheral surface of the holder part 19', and the outer peripheral part of the lower part of the yoke 4 and the holder part. A flow path space (injection valve bypass flow path) 18 that bypasses the injection valve 1 is formed between the inner circumferential surface 19 ′ and the inner peripheral surface.

The pipes forming the fuel supply conduit 19 are arranged on both sides of the holder portion 19 ′ so as to be orthogonal to the injection valve main body 1 and communicate with the flow passage space 18 secured on the outer periphery of the injection valve 1.

Further, the fuel inflow holes 13 and 13 'provided in the injection valve 1 face the upstream side of the fuel supply conduit 19 (the opening end 19a of the upstream side pipe),
The fuel outflow holes 14 and 14 'face the downstream side of the fuel supply conduit 19 (opening end 19b of the downstream pipe), so that a part of the fuel from the fuel supply conduit 19 is injected as shown in FIG. A first fuel flow A flowing inside the body of the valve 1 is formed. The inner diameter d of the fuel supply conduit 19 has holes 13,13 ', 14,1
It is much larger than 4 '. On the other hand, the above-mentioned injection valve bypass flow path 18 bypasses each fuel injection valve 1 by the flow path structure in the circumferential direction along the outer periphery of the injection valve main body, and bypasses between the upstream side pipe and the downstream side pipe of the fuel supply conduit 19. Communication is made in front of the fuel inlet 13 and immediately after the fuel outlet 14.

The injection valve bypass passage 18 of this embodiment has a boundary 19a between the fuel supply conduit 19 and the holder portion 19 '(a position before the fuel inflow hole 13).
Is divided into two parts, and the other boundary 19b (position immediately after the fuel outflow hole 14) forms one flow path structure.

Further, the injection nozzle 11 of each fuel injection valve 1 has a holder portion 19 '.
It is led out from the bottom wall.

Next, the operation of this embodiment will be described.

In the fuel injection system of this embodiment, when fuel is pumped into the fuel supply conduit 19 by a fuel pump (not shown),
Each time the fuel flowing in the fuel supply conduit 19 reaches the holder portion 19 ′, it is divided into a first fuel flow A and a second fuel flow B. In the first fuel flow A, the fuel is each fuel injector 1
When a part of the fuel flows from the internal flow passage 15 to the flow passage 4a through the fuel inflow hole 13 of the fuel injection hole 13 and the electromagnetic coil 2'is energized in this state, the ball 7 moves to the seat portion 12 The fuel is injected from the nozzle 11 while being measured. Further, the surplus fuel inside the injection valve body again flows out from the fuel outlet 14 to the downstream side pipe of the fuel supply conduit 19. Meanwhile, the second
In the fuel flow B, the fuel that did not flow into the fuel injection valve 1 passes through the injection valve installation location by a bifurcated flow through the flow path space 18 along the outer periphery of the injection valve main body 1 and again each fuel After merging downstream of the injection valve body 1, the fuel supply conduit 19
Flowing through.

In this embodiment, the fuel injection is performed based on the above basic operation, so that the engine startability at the time of hot restart can be ensured as follows.

At the time of hot restart, the ambient environment temperature of the fuel system is extremely high, and the fuel in the fuel supply conduit 19 and the fuel injection valve 1 is evaporated and filled with fuel vapor. However, in the present embodiment, the ignition key switch is turned on. When the fuel pump is activated, fresh fuel pumped through the fuel pump flows through the fuel supply conduit 19 and the holder portion 19 'for holding each injector in the series. This fuel flow is 1 for each holder part.
At 9 ', the fuel inlet 13 and the fuel outlet 14 of each fuel injection valve 1
The first fuel flow A passing inside the injection valve body by
The injection valve bypass passage 18 bypasses the inside of the injection valve main body to become the second fuel flow B along the outer periphery of the injection valve main body. Of these, the second fuel flow B is less than the inside of the injection valve main body. Since the passage passes through the injection valve bypass passage 18 having extremely small passage resistance, the flow has a high flow velocity, and due to the flow, a region where the pressure is lower than the inside of the injection valve main body near the fuel outlet 14 behind the injection valve main body (injection valve 1 And a fuel inlet 13, that is, a region (C) in which the pressure is relatively negative with respect to the pressure of the surface receiving the fuel flow is generated. In particular, such a second fuel flow B
According to this, as shown in FIG. 2, a eddy flow is generated near the fuel outlet 14 (merge position), which promotes the pressure drop.

Due to the existence of the low pressure region C, the fuel vapor (bubbles) staying in the fuel injection valve 1 at the time of hot restart is instantaneously drawn out of the injection valve main body, and the fuel inlet 13 and the fuel outlet 14 are also provided. The first fuel flow A passing through the inside of the main body of the fuel injection valve 1 via is also affected by the low pressure region C, and the flow velocity in the injection valve 1 is increased.

Therefore, due to the synergistic effect of these first and second fuel flows, the fuel that has accumulated inside the fuel supply conduit 19 and the fuel injection valve 1 before restarting is instantly swept away and new fuel is filled. The time required to fill this new fuel is, for example, about 1 to 2 seconds.

As a result, even if the engine is started immediately after the ignition key switch is turned on, proper fuel is circulated and fuel is injected. In this fuel injection, a part of the first fuel flow A flowing from the fuel inlet 13 of the fuel injection valve 1 into the injection valve main body is injected into the nozzle 11 through the valve portion 7 and the valve seat 12 of the injection valve main body. It is done by guiding.

Further, the fuel supply conduit 19, which supplies the fuel supply passage, the injection valve bypass passage 18 and the interior of the injection valve body are filled with the appropriate fuel immediately after the ignition key is turned on as described above, so that each fuel injection valve 1 is injected. Since it is cooled by the fuel passing through the inside and outside of the valve, the cooling effect of the injection valve itself has an immediate effect and effectively prevents the generation of bubbles inside the injection valve main body even when the environmental temperature of the fuel system is high. Further, even when bubbles are mixed from the outside, the bubbles can be drawn out of the injection valve by utilizing the back pressure effect.

Therefore, according to this embodiment, the fuel supply conduit 19
Of the fuel vapor generated in the fuel injection valve 1 and in the fuel injection valve 1 and promotion of forced cooling by the fuel of the fuel injection valve body can prevent the generation of bubbles and promote the removal of existing bubbles. It is possible to improve the engine speed and stabilize the engine speed after restart.

Further, in the present embodiment, by arranging the bottom feed type fuel injection valves 1 in series (in series) in the fuel supply conduit 19 which is made into one line, it is possible to improve the engine start. Since it is not necessary to provide a dedicated fuel system cooling means and a bubble removal dedicated means, the fuel system can be simplified.

〔The invention's effect〕

As described above, according to the present invention, it is possible to improve the restartability of the engine at the time of a hot start and stabilize the engine speed after the restart without complicating the engine system.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a partially omitted horizontal sectional view showing the internal structure of the fuel supply conduit used in this embodiment, and FIG. 3 is a partially omitted vertical sectional view of this embodiment. 1 ... Fuel injection valve, 2 ... Coil assembly, 5 ... Plunger, 7 ... Ball (valve body), 11 ... Injection nozzle, 13 ...
… Fuel inlet (hole), 14 …… Fuel outlet (hole), 15 ……
Internal flow path of injection valve, 18 ... Flow path space, 19, 19 '... Fuel supply passage (fuel supply conduit, holder part), A ... First fuel flow, B ... Second fuel flow, C: Low pressure area.

Claims (2)

[Claims] 1. A multi-point fuel injection device comprising a fuel injection valve (1) for each cylinder of an engine, wherein each fuel injection valve (1) has a fuel inlet ( The fuel injection valve is a bottom feed type fuel injection valve that injects fuel from 13) into the internal flow path of the injection valve body and causes uninjected surplus fuel to flow out from the fuel outlet (14) provided on the side wall of the injection valve body. , A fuel supply passage for guiding the fuel pressure-fed from the fuel pump to each of the fuel injection valves (1) is constituted by a line (19) lined into one line, and each of the above-mentioned lines is provided in the middle of this line (19). Each cylindrical holder part (19 ') accommodating and holding the fuel injection valve (1) is arranged in series through the pipe line (19), and the fuel inlet port (13) of each fuel injection valve (1). Faces the upstream side of the pipe (19), and the fuel outlet (14) is below the pipe (19). So as to form a first fuel flow A flowing inside the injection valve body facing the side, and between the outer circumference of the main body of each fuel injection valve (1) and the inner circumference of each holder part (19 ′). In between, the fuel flow is bypassed between the upstream pipe and the downstream pipe of the pipe (19) by bypassing each fuel injection valve (1) by the circumferential flow passage structure along the outer periphery of the injection valve body. An injection valve bypass passage (18) is formed which communicates with the position before the inlet (13) and immediately after the fuel outlet (14), and the second fuel flowing through the injection valve bypass passage (18) is formed. Due to the flow B, the fuel outlet (1
4) A multi-point fuel injection device characterized in that a region C where the pressure becomes low is generated in the vicinity. 2. The injection valve bypass passage (18) is divided into two passages immediately before the fuel inlet (13) of each fuel injection valve 1, and the fuel outlet (14) is provided along the outer periphery of the injection valve body. The multi-point fuel injection device according to claim 1, wherein the multi-point fuel injection device has a flow passage structure which is re-united at a position immediately after (1).