JP2003166455A - Electronically controlled fuel injection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance efficiency of discharging vapor in an electronically controlled fuel injection system having an electromagnetic driving type plunger pump. <P>SOLUTION: A recirculation passage 36 for connecting a supplying passage 30a and a returning passage 29a is formed on the outside of a yokes 24 and 25, a plunger passage 21c for connecting the returning passage 29a is formed inside a plunger 21 for reciprocating, an expansion and contraction chamber P for expanding and contracting according to the movement of the plunger 21 is formed between the plunger 21 and cylinders 22 and 23. This electronically controlled fuel injection system has an inside connection passage 21d for connecting the plunger passage 21c and the expansion and contraction chamber P and an outside connection passage 25a for connecting the expansion and contraction chamber P and the recirculation passage 36. Thus, pump action by the expansion and contraction chamber P is generated and forced flow of fuel is generated in passages and vapor can be forcibly discharged. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an internal combustion engine (hereinafter,
The present invention relates to an electromagnetically driven electronically controlled fuel injection device for injecting fuel into an intake passage (hereinafter simply referred to as an engine), and more particularly to an electronically controlled fuel injection device applied to an engine mounted on a motorcycle or the like.

[0002]

2. Description of the Related Art An electronically controlled fuel injection device applied to an engine mounted on a two-wheeled vehicle is disclosed in, for example, Japanese Patent Laid-Open No.
As disclosed in JP-A-01-221137, while the fuel guided from the fuel tank by the feed pipe is pressure-fed by the electromagnetically driven plunger pump, the surplus fuel and the generated vapor are returned to the fuel tank by the return pipe. It is known that the fuel in the initial region of the pressure feeding stroke is returned to the fuel tank by the return pipe and the fuel in the latter period of the pressure feeding stroke is injected from the injection nozzle toward the intake passage. In these devices, the fuel mixed with vapor (bubbles) is recirculated to the fuel tank in advance by the return pipe before the fuel pumped by the plunger pump is injected by the injection nozzle.

[0003]

By the way, in the above apparatus, the pressure in the feed pipe is reduced due to the passage resistance,
Alternatively, since vapor is generated in the fuel due to heat generation due to the operation of the plunger pump, it is necessary to efficiently remove the generated vapor. Further, when discharging the vapor toward the fuel tank, for example, when using natural convection (bubble pumping action) due to the upward flow of the vapor to discharge, without depending on the return pipe piping path, It is necessary to stably discharge the vapor even with a small amount of vapor without depending on the operating state of the engine.

The present invention has been made in view of the above points, and an object thereof is to provide a plunger pump with a simple structure without providing a special pump or the like for discharging vapor. It is an object of the present invention to provide an electronically controlled fuel injection device which can secure the cooling action of the above, can reliably discharge the generated vapor even when the amount of vapor generated is small, and can perform stable fuel injection.

[0005]

SUMMARY OF THE INVENTION An electronically controlled fuel injection system according to the present invention includes a plunger driven by electromagnetic force to suck and pump fuel by reciprocating motion, and a plunger slidably accommodated to store fuel. A cylinder that defines the pressure feed chamber, a supply passage that can communicate with the pressure feed chamber to supply fuel, a return passage that returns a portion of the supplied fuel to the original state, and a feed passage that is disposed downstream of the pressure feed chamber. An electronically controlled fuel injection device comprising an injection nozzle for injecting fuel, wherein a plunger passage formed inside the plunger and communicating with a return passage, and a movement of the plunger defined between the plunger and the cylinder body. It is characterized by having an expansion / contraction chamber that expands and contracts, an inner communication passage that communicates the plunger passage and the expansion chamber, and an outer communication passage that communicates the expansion chamber and the supply passage.

According to this structure, the reciprocating motion of the plunger sucks the fuel into the expansion chamber when the expansion chamber expands, and pushes the fuel out of the expansion chamber when the expansion chamber contracts. Therefore, the fuel pushed out from the expansion / contraction chamber through the inner communication passage is forced to flow through the plunger passage to the return passage, and in particular, the fuel in the plunger passage is forced toward the return passage by the return movement of the plunger. Shed That is, the fuel in the return passage can be forcibly discharged by generating a forced flow of fuel by the reciprocating motion of the plunger (pump action of the expansion / contraction chamber). This allows
Even with a small amount of vapor, the vapor generated regardless of the path of the return passage can be reliably discharged without staying.

In the above structure, it is possible to adopt a structure in which a recirculation passage for communicating the supply passage and the return passage for recirculating the fuel is provided outside the cylindrical body. According to this configuration,
The vapor generated in the supply passage flows out to the return passage via the return passage before being sucked into the pressure feeding chamber. Further, the fuel flowing in the return passage or the fuel mixed with vapor carries away the heat generated when the electromagnetic force is generated, so that a cooling action is also obtained, and the cooling action also suppresses the generation of vapor. Further, due to the reciprocating motion of the plunger, the fuel is sucked into the expansion chamber when the expansion chamber expands, and the fuel is pushed out of the expansion chamber when the expansion chamber contracts. Therefore, in addition to the fuel extruded from the expansion chamber through the inner communication passage is forced to flow through the plunger passage to the return passage,
The fuel extruded from the expansion / contraction chamber through the outer communication passage is forced to flow from the supply passage, that is, the return passage, to the return passage.
As a result, the vapor discharge efficiency is further improved.

In the above structure, in the inner communication passage and the outer communication passage, when the expansion chamber expands, the amount of fuel flowing from the outer communication passage into the expansion chamber is larger than that from the inner communication passage.
Further, when the expansion / contraction chamber contracts, it is possible to adopt a configuration in which the amount of fuel flowing out from the inner communication passage to the outside of the expansion / compression chamber is larger than that from the outer communication passage. According to this configuration, the pumping action of the expansion chamber expands the forced flow pushed from the inner communication passage to the return passage through the plunger passage, rather than the forced flow pushed from the outer communication passage to the supply passage side (or the return passage side). The flow increases. This increases the efficiency of vapor discharge from the plunger passage,
In addition, when the recirculation passage is provided, the vapor and the like inside the recirculation passage are sucked and discharged by the forced flow from the plunger passage, and even if the vapor is a small amount, the vapor generated regardless of the path of the return passage is removed. It can be reliably discharged without staying.

In the above structure, it is possible to employ a structure in which the outer communication passage is formed so that the passage resistance of the flow toward the inside of the expansion / contraction chamber is smaller than that of the flow toward the outside of the expansion / contraction chamber. According to this configuration, when the expansion chamber expands,
The fuel easily flows from the supply passage (or the return passage) toward the expansion / contraction chamber.

In the above structure, the outer communication passage may be a tapered passage whose passage area gradually decreases toward the expansion / contraction chamber. According to this structure, the outer communication passage is a tapered passage, so that the machining can be easily performed.

In the above structure, it is possible to adopt a structure in which the inner communication passage is formed so that the passage resistance of the flow from the expansion chamber to the plunger passage is smaller than that from the plunger passage to the expansion chamber. According to this structure, when the expansion / contraction chamber contracts, the fuel easily flows from the expansion / contraction chamber toward the plunger passage.

In the above structure, the inner communication passage may be a tapered passage whose passage area gradually decreases from the expansion / contraction chamber toward the plunger passage. According to this structure, since the inner communication passage is a tapered passage, it can be easily processed.

In the above structure, the plunger has an enlarged diameter portion having a predetermined diameter and a reduced diameter portion having a diameter smaller than the enlarged diameter portion, and the tubular body slidably accommodates the reduced diameter portion. And a diameter-reducing cylinder portion that defines the pressure-feeding chamber and a diameter-increasing cylinder portion that slidably accommodates the diameter-increasing portion, and the expansion and contraction chamber is defined by the diameter-reducing portion and the diameter-increasing cylindrical portion. Can be adopted. According to this configuration, the expansion / contraction chamber that functions as a pump can be formed easily and with a simple structure simply by adjusting the mutual shapes of the plunger and the cylinder without adding a separate component. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3
1 shows an embodiment of an electronically controlled fuel injection device according to the present invention, FIG. 1 is a fuel supply system diagram to which this device is applied, and FIGS. 2 and 3 are sectional views of this device.

A fuel supply system to which this device is applied is
As shown in FIG. 1, a motorcycle fuel tank 1 and an engine 2
Electronically controlled fuel injection device 1 disposed in the intake passage 2a of the vehicle
0, a feed pipe 3 forming a fuel supply passage, a low-pressure filter 4 arranged in the middle of the feed pipe 3, a return pipe 5 forming a return passage for returning a part of the supplied fuel to the fuel tank 1, an apparatus 10 A drive driver 6 and a control unit 7 for controlling the drive of the device are provided.

As shown in FIGS. 2 and 3, the electronically controlled fuel injection device 10 includes a plunger pump 20 that is driven by electromagnetic force to pump the fuel, and an injection that injects fuel pressurized above a predetermined pressure. It is composed of a nozzle 50 and the like. As shown in FIG. 2, the plunger pump 20 includes a plunger 21 and a plunger 21 that reciprocate in a substantially vertical direction.
Of the expanding cylinder 22 and the contracting cylinder 23, which are slidably accommodated in the cylinder, are arranged outside the expanding cylinder 22 and the contracting cylinder 23 to form a part of the cylindrical body and to form a magnetic circuit. Upper yoke 24 and lower yoke 2
5, a spacer 26 arranged between the upper yoke 24 and the lower yoke 25, a cylindrical bobbin 27 and a bobbin 27 arranged at a predetermined distance from the outer peripheral surfaces of the upper yoke 24 and the lower yoke 25. A return passage 29 connected to the wound excitation coil 28, the upper yoke 24, and the bobbin 27.
a return pipe 29 forming a, a supply pipe 30 connected to the lower yoke 25 and the bobbin 27 to form a supply passage 30a, a stopper 31 fixed to the upper yoke 24 and having a through hole 31a, a cover 32 for covering the whole. Is equipped with.

Here, the diameter-expanding cylinder 2 forming the cylinder body
2. In the diameter reduction cylinder 23, the upper yoke 24, and the lower yoke 25, the diameter expansion cylinder 22 and the lower yoke 25 form a diameter expansion cylinder portion, and the diameter reduction cylinder 23 forms a diameter reduction cylinder portion. An annular passage 34 is defined between the outer peripheral surfaces of the upper yoke 24 and the lower yoke 25 and the inner peripheral surface of the bobbin 27. As shown in FIGS. 2 and 3, the upper yoke 24 is provided with a plurality of slit-shaped passages 24a for communicating the annular passage 34 and the return passage 29a. In the lower region of the annular passage 34, the supply passage 3
A storage chamber 35 that communicates with 0a is formed.

The storage chamber 35, the annular passage 34, and the plurality of slit-shaped passages 24a form a supply passage 30a and a return passage 2.
A recirculation passage 36 that communicates with the fuel cell 9a and recirculates the fuel is formed outside the cylinder. Here, the return passage 36
The fuel flowing therethrough has a cooling effect of suppressing heat generation due to energization of the coil 28. In addition, the cooling action also suppresses the generation of vapor.

As shown in FIG. 2, the plunger 21 has a predetermined diameter and an enlarged diameter portion 21a slidably guided by the enlarged diameter cylinder 22 and a diameter reduced cylinder 23 having a diameter smaller than that of the enlarged diameter portion 21a. A reduced diameter portion 21b slidably guided to the inside, a plunger passage 21c formed inside the reduced diameter portion 21b and the enlarged diameter portion 21a and opening upward, and an inner communication passage 21d formed on the side wall of the reduced diameter portion 21b. And the like.

The expanded diameter portion 21a and the reduced diameter portion 21b, the expanded diameter cylinder 22, the lower yoke 25, and the reduced diameter cylinder 23 define an expansion and contraction chamber P that expands and contracts by the movement (reciprocating motion) of the plunger 21. There is. In the expansion / contraction chamber P, a return spring 3 for urging the plunger 21 upward is provided.
3 are accommodated. The return spring 33 biases the plunger 21 upward and presses it against the stopper 31 while the coil 28 is not energized. Further, in the diameter reducing cylinder 23 (cylindrical body), the lower end 21 of the diameter reducing portion 21b is
In a region below e, a pumping chamber D for pumping the sucked fuel is defined.

On the lower yoke 25, as shown in FIG.
An outer communication passage 25a is formed in the vicinity of where the lower end of the return spring 33 is seated. Further, the lower yoke 25 and the diameter-reducing cylinder 23 communicate the pressure feed chamber D and the storage chamber 35 at a position apart from the suction communication passages 25b and 23a that communicate the pressure feed chamber D and the storage chamber 35 and the supply passage 30a. The return communication passages 23b and 25c are formed.

In the suction communication passage 25b, the pumping chamber D
A check valve 37 and a spring 37a which allow only the inflow of fuel into the recirculation passage 25c are arranged.
A pressurizing valve 38 and a spring 38a which allow only the outflow of fuel and the like including vapor from the pressure feeding chamber D are arranged.

Return communication passages 23b, 25c and return passage 3
6, the fuel in the pumping chamber D is returned to the return passage 29a in a predetermined initial region of the pumping stroke by the plunger 21.
A second recirculation passage is formed to recirculate toward the end, and the fuel pressurized above a predetermined pressure is recirculated by the pressurizing valve 38 and the spring 38a.

In the above structure, the inner communication passage 21d is
The plunger passage 21c and the expansion / contraction chamber P are communicated with each other. Here, the passage is formed so that the passage has the same diameter, that is, the passage resistance is the same in any direction. .

The inner communication passage 21d may be formed so that the passage resistance of the flow from the expansion / contraction chamber P to the plunger passage 21a is smaller than that of the flow from the plunger passage 21c to the expansion / contraction chamber P. For example, a tapered passage may be formed in which the passage area gradually decreases from the expansion chamber P toward the plunger passage 21c. In this case, when the expansion / contraction chamber P contracts, the expansion / contraction chamber P moves to the plunger passage 2
The fuel easily flows out toward 1c.

Further, in the above structure, the outer communication passage 25
a communicates the expansion / contraction chamber P with the return passage 36 (annular passage 34), that is, also substantially communicates with the supply passage 30a. Here, the passage a is provided from the return passage 36 toward the expansion / contraction chamber P. It is formed in a tapered passage whose area gradually decreases. As a result, the passage resistance of the flow from the reflux passage 36 (or the supply passage 30a side) to the expansion / contraction chamber P is smaller than the flow resistance from the expansion / contraction chamber P to the return passage 36 (or the supply passage 30a side). In particular,
When the expansion / contraction chamber P is expanded,
It is easy for fuel to flow inward. The outer communication passage 25a may be formed as a cylindrical passage having the same diameter over the entire area.

The outer communication passage 25a and the inner communication passage 2
1d means that when the expansion chamber P expands, the inside communication passage 21d
When the amount of fuel flowing from the outer communication passage 25a into the expansion / contraction chamber P is larger than that from
It is formed such that the amount of fuel flowing out from the inner communication passage 21d to the outside of the expansion / contraction chamber P (toward the plunger passage 21c) is larger than that from the outer communication passage 25a.

Thus, the reciprocating motion of the plunger 21 causes the expansion / contraction chamber P to act as a pump, and the fuel flow from the return passage 36 (annular passage 34) to the return passage 29a via the expansion / contraction chamber P and the plunger passage 21c. Can be actively generated. Therefore, a forced flow is generated downstream from the return passage 29a, the vapor and the like accumulated in the return passage 36 and the like are drawn into this flow, and the return passage 2
The vapor and the like staying in 9a are also positively discharged.

As shown in FIG. 2, the injection nozzle 50 has a cylindrical member 51 forming a fuel passage 51a, a check valve 52 for allowing only outflow from a discharge passage 25d formed at the lower end of the pressure feeding chamber D, and a spring 52a. , An orifice nozzle 5 having an orifice portion 53a narrowed to a predetermined diameter
3, the poppet valve 54 and the spring 5 that open when the fuel passing through the orifice nozzle 53 has a predetermined pressure or more
4a, assist air pipe 55, assist air passage 56
And so on.

Next, the operation of this device will be described.
First, when the coil 28 is energized, an electromagnetic force is generated, and the plunger 21 in the standby state shown in FIG. 2 begins to move downward against the urging force of the return spring 33.
The pressure feeding stroke is started while pressurizing the fuel in the pressure feeding chamber D. Then, in the initial region of this pressure-feeding process, when the fuel to be pressure-fed becomes equal to or higher than a predetermined pressure (pressure), the pressure valve 38
To open the return communication passage 25c (second return passage), and the fuel mixed with vapor is discharged toward the return passage 29a through the return passage 36 (second return passage).

Subsequently, when the plunger 21 further moves to enter the latter region of the pumping stroke, the plunger 2
The side surface of 1 closes the reflux communication passage 23b of the diameter-reducing cylinder 23, and at the same time, the pressure of the fuel in the pumping chamber D is further increased.
That is, the plunger 21 functions as a valve body that closes the second recirculation passage (recirculation communication passage 23b) in the latter region of the pumping stroke.

Then, when the fuel in the pumping chamber D rises to a predetermined pressure, the check valve 52 opens, and the fuel having a predetermined pressure or more measured through the orifice nozzle 53 opens the poppet valve 54. At the same time, the fuel from which the vapor has been removed is injected into the intake passage 2a. At this time, since the assist air supplied from the assist air pipe 55 mixes with the fuel injected through the air passage 56, the fuel is injected in an atomized state.

On the other hand, when the plunger 21 moves downward, the expansion chamber P contracts, so that the fuel inside is pushed out. At this time, since the fuel is more likely to flow out of the inner communication passage 21d than in the outer communication passage 25a, the fuel inside is positively pushed out toward the plunger passage 21c. In addition, the return spring 33
Are compressed and concentrated in the lower region, so that the passage resistance of the lower space is increased, and the outer communication passage 25a to the return passage 36
It acts to suppress the outflow of fuel toward the.

The fuel pushed into the plunger passage 21c produces a forced flow toward the return passage 29a. Due to this forced flow, even if a small amount of vapor is used, or whatever the route of the return pipe 5 that forms the return passage, the return passage 36, the return passage 29a, and the inside of the return pipe 5 (return passage). In the above, the accumulation of vapor is prevented and the fuel is surely discharged toward the fuel tank 1.

When the coil 28 is de-energized after fuel injection, the return spring 33 urges the
The plunger 21 starts moving upward. At this time, the check valve 37 is opened, and the fuel in the supply passage 30a and the storage chamber 35 is sucked into the pressure feeding chamber D. Since the expansion / contraction chamber P expands when the plunger 21 moves upward, the fuel is sucked inward. At this time, the outer communication passage 25a is more than the inner communication passage 21d.
Since it is easy for fuel to flow in from the
The fuel in the (annular passage 34) positively flows toward the expansion / contraction chamber P. Since the return spring 33 extends upward from the compressed state, the passage resistance of the lower space is reduced, and the suction action is generated by the expansion of the interval between the windings, so that the fuel flows in from the outer communication passage 25a. Acts to promote.

The fuel in the plunger passage 21c is pushed upward as the plunger 21 moves upward, and a forced flow toward the return passage 29a is generated. Due to this forced flow, even in the case of a small amount of vapor, or whatever the route of the return pipe 5 that forms the return passage, the return passage 36, the return passage 29a, and the inside of the return pipe 5 are the same as described above. Accumulation of vapor in the (return passage) is prevented, and the fuel is reliably discharged toward the fuel tank 1. In the fuel injection, the above series of operations are continuously repeated.

FIG. 4 is a sectional view showing another embodiment of the electronically controlled fuel injection device according to the present invention. This device is the same as the device according to the above-described embodiment except that the second return passage and the pressurizing valve and the like associated therewith are changed, and therefore, the same components are designated by the same reference numerals. The description is omitted.

That is, in this apparatus, as shown in FIG. 4, the reduced diameter portion 21b 'of the plunger 21' is connected to the inner communication passage 21d ', the plunger passage 21c and the tip passage 21e' for communicating the pressure feed chamber D. Are formed. The inner communication passage 21d 'extends from the expansion / contraction chamber P to the plunger passage 21c.
The tapered passage has a passage area that gradually decreases toward the front side, and the fuel easily flows from the expansion / contraction chamber P toward the plunger passage 21c.

As shown in FIG. 4, the pressurizing valve 40 and the spring 4 which allow only the flow from the pumping chamber D to the plunger passage 21c are located inside the tip passage 21e '.
1 is arranged. That is, the tip passage 21e 'and the plunger passage 21c form a second return passage for returning the fuel toward the return passage 29a in a predetermined initial region of the pressure feeding stroke by the plunger 21c'.

A spill valve 42 as a valve body and a spring 43 are arranged in the pressure feed chamber D. The spill valve 42 has a contact portion 42a that can close the tip passage 21e ', a groove passage 42b that allows the flow of fuel, and the like. The spring 43 biases the spill valve 42 upward so as to contact the step portion 23c 'of the diameter-reducing cylinder 23'.

Next, the operation of this device will be described.
First, when the coil 28 is energized, an electromagnetic force is generated, and the plunger 21 ′ in the standby state shown in FIG. 4 begins to move downward against the urging force of the return spring 33, and the inside of the pumping chamber D The pressurization process is started while pressurizing the fuel. Then, in the initial region of this pressure-feeding stroke, when the fuel to be pressure-fed becomes equal to or higher than a predetermined pressure (pressurization), the pressurization valve 40 opens to open the tip passage 21e '(second reflux passage), Mixed fuel is the plunger passage 21c
It is discharged toward the return passage 29a through the (second return passage).

Then, when the plunger 21 'further moves into the latter region of the pumping stroke, the contact portion 42a of the spill valve 42 contacts the tip of the plunger 21' to close the tip passage 21e '. The fuel in the pumping chamber D is further pressurized while pushing down the spill valve 42. That is, the spill valve 42 closes the second recirculation passage (tip passage 21e ') in the latter region of the pumping stroke.

When the fuel in the pumping chamber D rises to a predetermined pressure, the check valve 52 opens, and the fuel having a predetermined pressure or more measured through the orifice nozzle 53 opens the poppet valve 54. At the same time, the fuel from which the vapor has been removed is injected into the intake passage 2a. At this time, since the assist air supplied from the assist air pipe 55 mixes with the fuel injected through the air passage 56, the fuel is injected in an atomized state.

On the other hand, when the plunger 21 'moves downward, the expansion / contraction chamber P contracts, so that the fuel inside is pushed out. At this time, the outer communication passage 25a
Since it is easier for the fuel to flow out from the inner communication passage (tapered passage) 21d ', the fuel inside is pushed out more positively toward the plunger passage 21c.

Then, the fuel pushed out into the plunger passage 21c produces a stronger forced flow toward the return passage 29a. Due to this forced flow, even if a small amount of vapor is used, or whatever the route of the return pipe 5 that forms the return passage, the return passage 36 and the return passage 29 are provided.
a, Vapor is prevented from accumulating in the return pipe 5 (return passage), and is reliably discharged toward the fuel tank 1.

When the coil 28 is de-energized after fuel injection, the return spring 33 urges the
The plunger 21 'begins to move upward. At this time, the check valve 37 is opened, and the fuel in the supply passage 30a and the storage chamber 35 is sucked into the pressure feeding chamber D. When the plunger 21 'moves upward, the expansion chamber P expands, so that the fuel is sucked inward.
At this time, the outer communication passage 2 is more than the inner communication passage 21d '.
Since the fuel easily flows in from 5a, the return passage 3
6 (annular passage 34) positively flows into the expansion / contraction chamber P.

The fuel in the plunger passage 21c is pushed upward with the upward movement of the plunger 21 ', and a forced flow toward the return passage 29a is generated. Due to this forced flow, even in the case of a small amount of vapor, or whatever the route of the return pipe 5 that forms the return passage, the return passage 36, the return passage 29a, and the inside of the return pipe 5 are the same as described above. Accumulation of vapor in the (return passage) is prevented, and the fuel is reliably discharged toward the fuel tank 1. In the fuel injection, the above series of operations are continuously repeated.

In the above embodiment, only the case where the return passage 36 is provided outside the cylindrical body is shown, but the present invention is not limited to this, and the return passage 3 shown in FIGS. 2 and 4, for example.
6 (annular passage 34 and slit-like passage 24a) is eliminated, the expansion / contraction chamber P, the supply passage 30a or the outer communication passage 25a for communicating the storage chamber 35 with the expansion / contraction chamber P, the expansion / contraction chamber P and the plunger passage 21c. You may employ | adopt the inner side communication path 21c which connects and. Also in this case, the plunger 2
By the pumping action of the expansion / contraction chamber P generated by the reciprocating movement of 1, the vapor can be positively discharged.

In the embodiment shown in FIG. 2, the outer communication passage 25a is a tapered passage, but it may be a cylindrical passage having the same diameter over the entire area, and the inner communication passage 21d is a cylindrical passage. Expansion chamber P to plunger passage 21c
It may be a tapered passage in which the passage area becomes smaller toward the end. In the embodiment shown in FIG. 4, the outer communication passage 25a and the inner communication passage 21d 'are both tapered passages, but either one may be a cylindrical passage, or
Both may be cylindrical passages.

That is, as long as the inner communication passages 21d and 21d 'for communicating the plunger passage 21c and the expansion / contraction chamber P and the outer communication passage 25a for communicating the expansion / contraction chamber P and the return passage 36 are provided, the expansion / contraction is performed. Since the forced flow of fuel can be generated by the pumping action of the chamber P, the accumulation of vapor can be prevented, and the vapor generated in the passage can be reliably discharged together with the fuel from the return passage 29a toward the fuel tank 1. it can.

[0051]

As described above, according to the electronically controlled fuel injection device of the present invention, the plunger itself is provided with a pump function for discharging the vapor, so that a special pump for discharging the vapor or the like is provided. With a simple structure, the generated vapor can be reliably discharged and the vapor generated can be reliably discharged regardless of the amount of vapor generated, regardless of the piping path of the return pipe. Fuel can be injected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a fuel supply system to which an electronically controlled fuel injection device according to the present invention is applied.

FIG. 2 is a sectional view showing an embodiment of an electronically controlled fuel injection device according to the present invention.

FIG. 3 is a cross-sectional view taken along the line AA of the device shown in FIG.

FIG. 4 is a sectional view showing another embodiment of the electronically controlled fuel injection device according to the present invention.

[Explanation of symbols]

1 fuel tank 2a Intake passage 3 Feed pipe (supply passage) 4 Low pressure filter 5 Return pipe (return passage) 10,10 'Electronically controlled fuel injection device 21 Plunger (valve) 21 'Plunger 21a Expanding part 21b, 21b 'reduced diameter portion 21c Plunger passage 21d, 21d 'inner communication passage 21e 'tip passage 22 Expanding cylinder (cylindrical body) 23,23 'Reduced diameter cylinder (cylindrical body) 23b Return communication passage (second return passage) 24 Upper yoke 24a Slit-shaped passage (reflux passage) 25 Lower yoke (cylindrical body) 25a outside communication passage 25c Return communication passage (second return passage) 27 bobbins 28 coils 29 Return pipe 29a Return passage 30 supply pipes 30a supply passage 33 Return spring 34 Circular passage (return passage) 35 Storage chamber (reflux passage) 36 Return passage 37 Check valve 37a, 38a, 41, 43 springs 38,40 Pressurizing valve 42 spill valve 50 injection nozzles P expansion chamber D pumping room

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Mizui             2480 Kuno, Odawara-shi, Kanagawa Co., Ltd.             Mikuni Odawara Office (72) Inventor Tadashi Nijo Tadashi             2480 Kuno, Odawara-shi, Kanagawa Co., Ltd.             Mikuni Odawara Office F term (reference) 3G066 AA01 AB02 AC07 AD02 AD07                       BA37 CA03 CA09 CA18 CA21                       CA34 CA35 CC06T CC40                       CC64S CC67 CE13 CE22

Claims (8)

[Claims] 1. A plunger driven by electromagnetic force so as to suck and pump fuel by reciprocation, a cylindrical body slidably accommodating the plunger to define a pumping chamber for fuel, and supplying fuel. A supply passage capable of communicating with the pressure feeding chamber, and a return passage for returning a part of the supplied fuel to the original state,
An electronically controlled fuel injection device, comprising: an injection nozzle that is arranged downstream of the pressure supply chamber and injects the fuel that has been pressure-fed; a plunger passage that is formed inside the plunger and communicates with the return passage; An expansion / contraction chamber that is defined between the plunger and the cylindrical body and expands and contracts due to the movement of the plunger; an inner communication passage that connects the plunger passage and the expansion / contraction chamber; and the expansion / contraction chamber and the supply passage. And an outer communication passage communicating with the electronic control fuel injection device. 2. The electronically controlled fuel injection device according to claim 1, further comprising a recirculation passage, which communicates the supply passage and the return passage with each other, for recirculating the fuel, on the outer side of the cylindrical body. 3. The inner communication passage and the outer communication passage,
When the expansion chamber expands, a larger amount of fuel flows into the expansion chamber from the outer communication passage than from the inner communication passage, and when the expansion chamber contracts, the outer communication passage 3. The electronically controlled fuel injection device according to claim 1, wherein the amount of fuel flowing out from the inner communication passage to the outside of the expansion / contraction chamber is larger than that from the internal communication passage. 4. The outer communication passage is formed so that a passage resistance of a flow toward the inside of the expansion chamber is smaller than a passage resistance of a flow toward the outside of the expansion chamber. Item 4. An electronically controlled fuel injection device according to any one of items 1 to 3. 5. The electronically controlled fuel injection device according to claim 4, wherein the outer communication passage is a tapered passage whose passage area gradually decreases toward the expansion / contraction chamber. 6. The inner communication passage is formed so that a passage resistance of a flow from the expansion chamber to the plunger passage is smaller than a passage resistance from a flow from the plunger passage to the expansion chamber. The electronically controlled fuel injection device according to any one of claims 1 to 5. 7. The electronically controlled fuel injection device according to claim 6, wherein the inner communication passage is a tapered passage whose passage area gradually decreases from the expansion chamber to the plunger passage. . 8. The plunger has an enlarged diameter portion having a predetermined diameter and a reduced diameter portion having a diameter smaller than the enlarged diameter portion, and the cylindrical body slides on the reduced diameter portion. The expansion / contraction chamber includes a diameter-reducing cylinder portion that freely accommodates and defines the pumping chamber, and a diameter-increasing cylinder portion that slidably accommodates the diameter-expansion portion. The electronically controlled fuel injection device according to any one of claims 1 to 7, wherein the electronically controlled fuel injection device is defined by a tubular portion.