JP2000199466A - Fuel injection system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain sufficient sealing performance between a fuel injection valve and a fuel supply pipe even in a case where high fuel pressure is generated in the fuel supply pipe such as a delivery pipe. SOLUTION: When a delivery pipe body 70A and an adapter 70B are integrated with each other, an insertion hole of an insertion portion 61 of a fuel injection valve 60 is formed from an insertion hole 75 of the adapter 70B toward an insertion hole 74 of the delivery pipe body 70A. Further, in the midway of this insertion hole, an enlarged diameter portion 76 is formed, where an O-ring 80 for sealing fuel and backup rings 81, 82 are housed. According to the configuration of thus mounting the O-ring 80 to the enlarged diameter portion 76, a small pressure-receiving face a1 can be formed. Therefore, a high performance of the O-ring 80 is ensured even in the case of high fuel pressure.

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 an internal combustion engine that injects fuel into the internal combustion engine, and is particularly suitable for use in an internal combustion engine such as a direct injection internal combustion engine that is supplied with high pressure fuel. Related to a simple fuel injection device.

[0002]

2. Description of the Related Art In recent years, as an internal combustion engine such as a vehicle-mounted engine, an in-cylinder injection type for directly injecting fuel into a combustion chamber for the purpose of improving fuel efficiency has been put to practical use. In such a cylinder injection type internal combustion engine, fuel is injected into a combustion chamber in a high pressure state, so that the fuel in a fuel tank is pressurized by a high pressure fuel pump and fed to a delivery pipe (fuel supply pipe). Fuel is directly injected into the combustion chamber from a fuel injection valve connected to a pipe.

FIG. 4 shows an example of a combustion chamber of a direct injection gasoline engine for a vehicle and a fuel injection device for injecting fuel into the combustion chamber. As shown in the figure, a piston 130 is provided in a cylinder block 120 of the engine 110 so as to be able to reciprocate for each cylinder of the engine 110 (only one piston is shown in FIG. 4). The cylinder head 140 provided above the cylinder block 120 is provided with a fuel injection valve 160 for directly injecting fuel into a combustion chamber 150 located between the piston 130 and the cylinder head 140.

The fuel injection valve 160 has a delivery pipe 17 through which fuel is pressure-fed from a high-pressure fuel pump (not shown).
0 is connected, and the fuel injection valve 160 and the delivery pipe 170 constitute a fuel injection device. The fuel pumped from the high-pressure fuel pump is supplied to the fuel injection valve 160 through a fuel supply passage in the delivery pipe 170.
Will be supplied to When the fuel injected and supplied from the fuel injection valve 160 is burned in the combustion chamber 150 based on the ignition of the spark plug 200, the energy generated by the combustion causes the piston 130 to reciprocate to drive the engine 110. .

In FIG. 5, the fuel injection device (fuel injection valve 160 and delivery pipe 170) of the engine 110 shown in FIG. 4 is connected to the combustion chamber 150 from the delivery pipe 170 side along the axis L1 of the fuel injection valve 160. 2 schematically shows a planar structure when viewed from the side.

[0006] As shown in FIG.
0 indicates a plurality of mounting portions 23 for the cylinder head 140.
0 are provided at predetermined intervals along the longitudinal direction of the delivery pipe 170. When attaching the delivery pipe 170 to the cylinder head 140, the bolt 250 is screwed into a corresponding attachment hole (not shown) of the cylinder head 140 via a through hole (not shown) provided in the attachment portion 230. It is performed by

The fuel injection valve 160 has the fuel injection port 160a side inserted in the insertion hole 260 of the cylinder head 140 and the fuel supply port 160b side inserted in the insertion hole 170a of the delivery pipe 170 in the manner shown in FIG.
When the delivery pipe 170 is attached in the above-described mode, the delivery pipe 170 is fixed between the cylinder head 140 and the delivery pipe 170 in a state of being sandwiched between them. In FIG. 4, reference numeral 190 indicates a connection portion between the fuel injection valve 160 and the delivery pipe 170 that constitute the fuel injection device.

[0008]

FIG. 6 shows a connecting portion 1 between the fuel injection valve 160 and the delivery pipe 170. As shown in FIG.
As shown schematically by enlarging 90, this connecting portion 190
In the fuel injection valve 160, an O (o) ring 180 as a seal ring and backup rings 181 to 183 are attached to a connection portion thereof.
Reference numeral 60 denotes a delivery pipe 1 through these seal rings.
70 into the insertion hole 170a. Therefore, in the connection portion 190, the connection end face of the fuel injection valve 160 is connected to the pressure receiving surface A1 of the fuel pressure P in the delivery pipe 170.
Thus, a large reaction force P 'corresponding to the fuel pressure P acts on the pressure receiving surface A1. 4 and 5
As shown in FIG.
Have their respective central axes L1 and L2 separated from each other by a distance L (offset). Therefore, FIG.
As schematically shown in the side view, the component force P1 of the reaction force P ′ corresponding to the fuel pressure P acting on the pressure receiving surface A1 of the fuel injection valve 160 causes the contact between the cylinder head 140 and the delivery pipe 170. A moment is generated in the delivery pipe 170 with the portion as the axis Q.

[0009] Such a moment is originally defined by the axis L
Delivery pipe 170 and its insertion hole 1
The shift of the center line of each of the joints 70a causes the shift (eccentricity) of the seals 70a to cause unevenness in the compression ratio of the seal ring (mainly the O-ring 180) provided in the connection portion 190. Such a change in the compression ratio of the seal ring significantly reduces the sealing performance.

[0010] Conventionally, for example, Japanese Patent Application Laid-Open No. 8-31502 is disclosed.
As disclosed in Japanese Unexamined Patent Publication, a structure is also known in which mounting holes for the fuel injection valve and the bolt are arranged on the delivery pipe so that the fuel injection valve and the bolt are close to each other. However, in the case of the same structure, there is no fundamental solution to the reduction in sealing performance due to the eccentricity between the fuel injection valve and the delivery pipe.

The present invention has been made in view of such circumstances, and has as its object to provide a fuel injection valve and a fuel supply pipe even when a high fuel pressure is generated in a fuel supply pipe such as a delivery pipe. It is an object of the present invention to provide a fuel injection device for an internal combustion engine that can guarantee a sufficient sealing performance between the fuel injection and the internal combustion engine.

[0012]

According to one aspect of the present invention, there is provided a fuel injection valve for supplying fuel to an internal combustion engine, the fuel injection valve sealing the fuel. In a fuel injection device for an internal combustion engine, which is inserted and mounted on a fuel supply pipe via a seal ring for the fuel supply pipe, the fuel supply pipe has an enlarged diameter portion in the middle of an insertion hole of the fuel injection valve, and the seal ring is The gist is that the large diameter portion is provided inside the fuel supply pipe.

According to this structure, the inside diameter of the insertion hole can be reduced by accommodating the seal ring in the enlarged diameter portion, and the pressure receiving surface of the fuel pressure in the fuel supply pipe with respect to the fuel injection valve is reduced. As a result, the load on the fuel injection valve due to the fuel pressure is reduced. In other words, the sum of the pressures that the fuel injection valve receives from the fuel in the fuel supply pipe is reduced, and the moment generated around the mounting portion of the delivery pipe is also reduced, so that the connection portion between the fuel injection valve and the fuel supply pipe is displaced. Is reduced, and the sealing performance at the connection site is improved. Therefore,
Even in a fuel injection device in which the fuel pressure in the fuel supply pipe is high, such as an in-cylinder injection internal combustion engine, sufficient sealing performance by the seal ring is guaranteed at the connection between the fuel injection valve and the fuel supply pipe. Become like

According to a second aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first aspect, the fuel supply pipe has a fuel supply pipe main body and an insertion hole for the fuel injection valve. An adapter that is screwed to the tip of the fuel injection valve insertion hole of the pipe main body, wherein the enlarged diameter portion is provided between the tip of the fuel injection valve insertion hole of the fuel supply pipe main body and the adapter. The gist is to be formed.

According to this configuration, the enlarged diameter portion can be easily formed in an assembled state in which an adapter is connected to the tip of the insertion hole of the fuel supply pipe body by screwing.

According to a third aspect of the present invention, in the fuel injection device for an internal combustion engine according to the second aspect, the outer diameter of the seal ring is D, and the diameter of a threaded portion of the adapter with the fuel supply pipe main body is d. In this case, the gist is that the diameters are set in a relation of D <d.

According to the above construction, the seal ring does not come into contact with the threaded portion when assembling the tip of the insertion hole of the fuel supply pipe body with the adapter, and the seal ring is not damaged by the threaded portion. Can be suitably prevented.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which a fuel injection device according to the present invention is applied to a fuel injection device for a vehicle-mounted in-cylinder injection gasoline engine will be described with reference to FIGS.

The in-cylinder in-cylinder gasoline engine (hereinafter referred to as engine) on which the fuel injection device of the present embodiment is mounted is the engine 11 previously described with reference to FIG.
0, and the detailed description thereof is omitted. Also, in the fuel injection valve and the delivery pipe (fuel supply pipe) constituting the fuel injection device of the present embodiment, except for the portion related to the connection structure between these two members, the arrangement position with respect to the engine and the mounting structure of the delivery pipe. 4 and FIG. 5 is substantially the same as that of the prior art shown in FIGS. 4 and 5, and here, the connection structure between the fuel injection valve and the delivery pipe, which is different from the conventional fuel injection device, is mainly described. It will be explained.

FIG. 1A schematically shows a cross-sectional structure of a connection portion between the fuel injection valve and the delivery pipe of the fuel injection device of the present embodiment. In this fuel injection device,
The fuel injection valve 60 includes a fuel supply port 60b that opens toward the inside of the delivery pipe 70, and an electromagnetic valve (not shown) that opens and closes in response to a control signal from an electronic control unit (not shown). Then, the fuel held at a high pressure is introduced from the delivery pipe 70 into the fuel supply port 60b,
The solenoid valve is opened as appropriate, and fuel is directly injected and supplied from its tip (fuel injection port) to the combustion chamber of the engine.

In the fuel injection device according to the present embodiment,
An insertion portion 61 having an outer diameter smaller than the main body of the fuel injection valve 60 is formed at the upstream end portion of the fuel injection valve 60. The insertion portion 61 includes a cylindrical portion 61 a having a cylindrical shape and a tapered end portion 6 having a truncated cone (taper) shape.
1b.

On the other hand, in the same fuel injection device, a delivery pipe 70 is provided with an insertion hole 74 into which the insertion portion 61 of the fuel injection valve 60 is inserted while fuel is fed from a high-pressure fuel pump (not shown). It comprises a pipe body 70A and an adapter 70B that can be separated from the delivery pipe body 70A.

Here, the delivery pipe body 70A includes a first cylindrical portion 71 and a second cylindrical portion 71 having an outer diameter smaller than that of the first cylindrical portion 71.
It has a cylindrical portion 72 and a third cylindrical portion 73 having a smaller outer diameter than the second cylindrical portion, and has a stepped cylindrical shape in which the outer diameter decreases as approaching the tip. The top end of the delivery pipe main body 70A is a flat surface, and the insertion hole 74 for inserting the insertion portion 61 of the fuel injection valve 60 is opened at the center thereof.

On the other hand, the adapter 70B also has a cylindrical outer shape, and the fuel injection valve 60
An insertion hole 75 for inserting the insertion portion 61 is formed,
At the center of the end face forming the other end via the middle diameter enlarged portion 76, a connection hole 77 that is further enlarged in diameter and connected to the delivery pipe main body 70A is formed. A female screw is formed on the inner peripheral surface of the connection hole 77, and a male screw is formed on the second cylindrical portion 72 of the delivery pipe main body 70A. The adapter 70B is attached to the delivery pipe main body 70A. They are connected by screws. Further, a copper washer 84 seals between the end surface of the adapter 70B where the connection hole 77 is formed and the opposing surface of the delivery pipe main body 70A.

The delivery pipe body 70A and the adapter 70
When B is assembled in this manner, an insertion hole for the fuel injection valve 60 is formed from the insertion hole 75 of the adapter 70B to the insertion hole 74 of the delivery pipe main body 70A. And
The enlarged diameter portion 7 formed in the middle of the adapter 70B
Reference numeral 6 also denotes an enlarged diameter portion in the insertion hole of the fuel injection valve 60, in which an O-ring 80 for fuel sealing and backup rings 81 and 82 are accommodated. The O-ring 80 itself has a predetermined elasticity, and is capable of expanding and contracting and restoring the pressing force toward the inner periphery of the O-ring 80.
1B, the outer diameter D of the O-ring 80 is different from that of the adapter 70.
The diameter is set relatively smaller than the inner diameter d of the connection hole 77 in which the female screw B is cut.

That is, the outer diameter D of these O-rings 80
And the inner diameter d of the connection hole 77 has the following relationship: D <d (1) This is to prevent the O-ring 80 from coming into contact with the female screw portion corresponding to the inner wall of the connection hole 77 when the delivery pipe main body 70A and the adapter 70B are assembled, thereby preventing the ring 80 from being damaged.

Next, a procedure for assembling the fuel injection device according to the present embodiment will be described with reference to FIGS. As shown in FIG. 2A, in addition to these members, an O-ring 80, backup rings 81 and 82, and a copper washer 84 are used for assembling the fuel injection valve 60, the delivery pipe main body 70A, and the adapter 70B. . When assembling, first, backup rings 81 and 82 and an O-ring 80 are sequentially fitted into the adapter 70B. Next, an adapter 70B in which these seal rings are inserted is screwed into a delivery pipe body 70A in which copper washers 84 are inserted.

Subsequently, as shown in FIG. 2 (b), the insertion portion 61 of the fuel injection valve 60 is inserted into the insertion holes 75 and 74 of the integrated delivery pipe 70, and the delivery pipe 70 is extended to the base end thereof. Stuff.

Thereafter, the fuel injection valve 60 and the delivery pipe 70 assembled above are connected to the cylinder head 14.
2 (see FIG. 4), the delivery pipe 70 is pulled back by the minute interval α in the mode shown in FIG. 2 (c).
By this retraction, if there is any distortion in the O-ring 80, it is corrected and the mounting shape is stabilized.

The operation of the fuel injection device of the present embodiment configured as described above will be described below. As described above with reference to FIG. 6, in the conventional fuel injection device, at the connection portion between the fuel injection valve and the delivery pipe, in addition to the insertion portion of the fuel injection valve into the delivery pipe, up to the outer peripheral portion of the seal ring. The fuel pressure in the delivery pipe was to be received. Therefore, as shown in FIG. 7, the reaction force of the fuel pressure promotes non-uniform compression of the seal ring between the fuel injection valve and the delivery pipe around the mounting portion of the delivery pipe to the cylinder head. A moment is generated, and as a result, the sealing performance is greatly reduced.

In this regard, according to the fuel injection device of this embodiment, as shown in FIG. 1A, the delivery pipe 70 is provided with the enlarged diameter portion 76 in the insertion hole of the fuel injection valve 60, The seal ring is accommodated in the enlarged diameter portion 76. With such a configuration, in the delivery pipe 70, the fuel pressure receiving surface a1 of the fuel injection valve 60 is significantly reduced as compared with the pressure receiving surface A1 of the above-described conventional fuel injection valve. It is possible to reduce the moment itself generated around the connection portion 70. As a result, uneven compression of the seal ring generated at the connection site can be suitably suppressed, and the sealing performance of the connection site can be highly guaranteed.

In the present embodiment, since the above-described enlarged diameter portion 76 is obtained by coupling the adapter 70B to the delivery pipe main body 70A, the formation thereof is also easy.

Further, as described in relational expression (1), since the inner diameter d of the connection hole 77 of the adapter 70B is formed to be larger than the outer diameter D of the O-ring 80, the O-ring 80 is When assembling to 70B
The O-ring 8 is formed by a male screw cut in the connection hole 77.
0 is not hurt.

When the deviation between the delivery pipe 70 and the fuel injection valve 60 is reduced, vibration and noise caused by such deviation are suppressed. In addition, since the load (load) on the fuel injection valve 60 due to the fuel pressure in the delivery pipe 70 is reduced, the rigidity of the connection portion between the fuel injection valve 60 and the delivery pipe 70 increases. Further, since the moment for causing the connection portion to be deflected is reduced, it is necessary to mount the fuel injection valve 60 and the delivery pipe 70 to the cylinder head 140, including the strength required for the mounting bolt of the delivery pipe 70, for example. The strength is reduced, and the size of the device can be reduced. Moreover, in the above configuration, the O-ring adapter 70B
Since there is no need to expand the inner diameter of the O-ring 80 when mounting the O-ring 80, the assembling process can be easily automated. Also, by adopting such an adapter 70B,
The arrangement of the backup ring 183 (FIG. 6) required in the conventional fuel injection device is not required. Incidentally, in the conventional configuration, when removing the fuel injection valve 60 from the delivery pipe 70, it is necessary to dispose the backup ring 83 so that the O-ring 180 is not left in the insertion hole 170a.

As described in detail above, according to the present embodiment, the following effects can be obtained. (1) The moment generated at the connection portion between the fuel injection valve 60 and the delivery pipe 70 is reduced, and the bias generated at the connection portion can be suitably suppressed. As a result, a high sealing performance at the connection site is assured. (2) Vibration and noise caused by the deviation generated at the connection portion between the fuel injection valve 60 and the delivery pipe 70 are suppressed. (3) By adopting the adapter 70B, the fuel injection valve 6
An enlarged diameter portion can be easily formed at a connection portion between the delivery pipe 70 and the delivery pipe 70. (4) When the fuel injection valve 60 and the delivery pipe 70 are assembled, damage to the O-ring 80 can be suitably prevented. (5) The rigidity of the connection portion between the fuel injection valve 60 and the delivery pipe 70 is increased, and the size of the device is easily reduced. (6) The attachment of the O-ring 80 to the adapter 70B is simplified, and the attachment process is easily automated.

In the above embodiment, the delivery pipe main body 70A and the adapter 70B are the same as those shown in FIGS.
As described above, a male screw is cut on the delivery pipe 70A side and a female screw is cut on the adapter 70B side, and these two members are screwed together. Alternatively, for example, as shown in FIG.
B 'may be screwed into the delivery pipe main body 70A' with a female thread. In short, the delivery pipe 70A (70A ′) and the adapter 70B (70
It is sufficient that the enlarged diameter portion is formed in the insertion hole of the fuel injection valve 60 by the connection of B ′). In that sense, a structure in which the delivery pipe main body 70A '' and the adapter 70B '' are further connected in a manner shown in FIG. Also with this connection structure, an enlarged diameter portion can be formed in the insertion hole of the fuel injection valve 60, and the same effect as in the above embodiment can be obtained. In addition, these FIG.
In the devices illustrated in (a) and (b), the O-ring 80 is mounted on the delivery pipe main body side when assembling them.

Further, in the above embodiment, the present invention is applied to a vehicle-mounted in-cylinder injection gasoline engine. However, this engine is a diesel engine that introduces high-pressure fuel stored in a common rail as a fuel supply pipe into a fuel injection valve. It may be an engine.

The present invention has a particularly remarkable effect when applied to a direct injection internal combustion engine in which the fuel in a fuel supply pipe such as a delivery pipe or a common rail has a high pressure, but is not limited to this. The fuel injection device according to the present invention can be applied to an internal combustion engine that supplies fuel to an intake passage from a supply pipe via a fuel injection valve. And even in that case, the sealing performance at the connection between the fuel injection valve and the fuel supply pipe can be suitably ensured.

Further, the fuel injection valve is not limited to the one having a built-in electromagnetic on-off valve, and the present invention can be applied to any fuel injection valve that requires a high sealing performance at the fuel introduction part.

[0040]

According to the structure of the first aspect of the present invention, the sum of the pressures received by the fuel injection valve from the fuel in the fuel supply pipe is reduced, and the moment generated about the mounting portion of the delivery pipe as an axis. Therefore, the deviation of the connecting portion between the fuel injection valve and the fuel supply pipe is reduced, and the sealing performance of the connecting portion is improved.
Therefore, even in a fuel injection device such as an in-cylinder injection type internal combustion engine in which the fuel pressure in the fuel supply pipe is high, sufficient sealing performance by the seal ring at the connection between the fuel injection valve and the fuel supply pipe is guaranteed. Will be done.

According to the second aspect of the present invention, the enlarged-diameter portion can be easily formed in an assembling mode in which the adapter is connected to the tip of the insertion hole of the fuel supply pipe body by screwing. Become.

According to the third aspect of the present invention, when assembling the tip of the insertion hole of the fuel supply pipe main body with the adapter, the seal member does not come into contact with the screw portion, and the seal member is screwed. It is possible to suitably prevent the part from being damaged.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view partially showing a connection structure of a fuel injection valve and a delivery pipe of an embodiment of a fuel injection device of the present invention.

FIG. 2 is a sectional view partially showing an assembling mode of the fuel injection device according to the embodiment;

FIG. 3 is an exemplary sectional view partially showing a modification of the embodiment;

FIG. 4 is a cross-sectional view schematically showing a vehicle-mounted in-cylinder injection gasoline engine and its fuel injection device.

FIG. 5 is a plan view showing a mounting structure of a delivery pipe to a cylinder head.

FIG. 6 is a cross-sectional view partially showing a connection structure of a fuel injection valve and a delivery pipe of a conventional fuel injection device.

FIG. 7 is a side view showing a structure for attaching a delivery pipe to a cylinder head.

[Explanation of symbols]

Reference numeral 60: fuel injection valve, 60b: fuel supply port, 61: insertion portion, 70, 170: delivery pipe, 70A, 70
A ', 70A''... delivery pipe body, 70B, 70
B ′, 70B ″: Adapter, 71: First cylindrical portion, 72
... second cylindrical portion, 73 ... third cylindrical portion, 74, 75 ... insertion hole, 76 ... enlarged diameter portion, 77 ... connection hole, 80, 180 ... O-ring, 81, 82, 181, 182, 183 ... backup ring , 84 ... copper washer, 110 ... engine, 1
20 ... cylinder block, 130 ... piston, 140 ...
Cylinder head, 150: combustion chamber, 160: fuel injection valve, 180: fuel supply passage, 190: connection portion, 190a
... Insert hole, 200 ... Spark plug, 230 ... Mounting part, 25
0 ... bolts.

Claims (3)

[Claims] 1. A fuel injection device for an internal combustion engine having a fuel injection valve for injecting fuel into the internal combustion engine, wherein the fuel injection valve is inserted and mounted in a fuel supply pipe via a seal ring for sealing the fuel. In the internal combustion engine, wherein the fuel supply pipe has an enlarged portion in the middle of an insertion hole of the fuel injection valve, and the seal ring is provided inside the fuel supply pipe at the enlarged portion. Fuel injection device. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel supply pipe has a fuel supply pipe main body and an insertion hole for the fuel injection valve, and the fuel injection valve of the fuel supply pipe main body. An adapter screwed to the tip of the insertion hole, wherein the enlarged diameter portion is formed between the tip of the fuel injection valve insertion hole of the fuel supply pipe main body and the adapter. A fuel injection device for an internal combustion engine. 3. The fuel injection device for an internal combustion engine according to claim 2, wherein D is an outer diameter of the seal ring, and d is a diameter of a threaded portion of the adapter with the fuel supply pipe main body. Is set to satisfy the following relationship: D <d.