JP2000027736A - Fuel injection device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep high sealability of a fuel injection device of cylinder direct injection type while providing a simple structure enabling reduction of the number of items. SOLUTION: This type of fuel injection device has a fuel injector 50 whose nozzle body 52 is inserted into a nozzle insertion hole 12N of an engine head 12. Fuel is directly injected into a combustion chamber 30 of an engine from an nozzle hole 53 formed on a front of the nozzle body 52 of the fuel injector 50. A plurality of circumferential grooves 52a to 52d composing a capacity part are partitioned on the nozzle body 52 in an axial direction. The capacity of the grooves 52a to 52d are gradually decreased sequentially from the one nearmost the combustion chamber 30.

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 engine, and more particularly to an improvement in a device structure suitable for use in a direct injection fuel injection device for directly injecting fuel into a combustion chamber of an engine.

[0002]

2. Description of the Related Art Conventionally, as this type of fuel injection device,
For example, an apparatus described in JP-A-10-30527, an apparatus described in JP-A-10-37829, and the like are known.

[0003] As can be seen from the devices described in these publications, this type of fuel injection device is usually provided with a nozzle insertion hole provided in a cylinder head (engine head) of an engine so as to penetrate to a combustion chamber, The fuel injection device is provided with a fuel injector attached so that the nozzle body is inserted into the insertion hole. In this manner, the injector attached to the engine head has the tip of the nozzle body exposed to the combustion chamber of the engine, and directly injects fuel into the combustion chamber from the injection hole formed at the tip of the nozzle body. I will be.

[0004] By adopting such a fuel injection device for in-cylinder direct injection, a so-called stratified combustion in which a flammable air-fuel mixture is locally formed in a gasoline engine is enabled, so that a gasoline engine has the same performance as a diesel engine. It is well known that both fuel economy characteristics and exhaust characteristics (cleanness) as a gasoline engine can be achieved.

[0005]

As described above, in the fuel injection device for in-cylinder direct injection, the fuel is directly injected into the combustion chamber of the engine from the injection hole formed at the tip of the nozzle body of the injector. By adopting such an injection form, a local combustible mixture for realizing stratified combustion can be formed.

However, the fuel injection device has a structure in which the tip end of the nozzle body is exposed to the combustion chamber of the engine. Therefore, the high-pressure combustion gas generated in the combustion chamber can be reliably used. Sealing must be performed, and the sealing structure naturally requires high sealing performance.

[0007] For this reason, even in the apparatus described in the above publication, a complicated sealing structure is inevitable, such as providing a double washer and a gasket between the retaining nut and the engine head. The increase or the accompanying cost increase is unavoidable.

It should be noted that not only gasoline engines but also diesel engines have a fuel injection device having a direct fuel injection nozzle for in-cylinder direct injection as a fuel injection means. Has become.

The present invention has been made in view of the above circumstances, and provides a fuel injection device for an engine which can maintain high sealing performance while having a simple structure capable of reducing the number of parts. With the goal.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, fuel injection means (fuel injector, fuel injection, fuel injection) mounted so that a nozzle body is inserted into a nozzle insertion hole of an engine head. An injection hole formed at a tip end portion of the nozzle body of the fuel injection means, wherein the fuel is directly injected into a combustion chamber of the engine. The device is configured as provided with a volume portion forming a concave space on at least one of the inner peripheral surfaces of the holes.

According to the first aspect of the present invention, when the fuel injection means is mounted on the engine head, the volume formed between the nozzle body and the nozzle insertion hole is located in the combustion chamber. The high-pressure combustion gas which is generated and leaks from a gap (clearance) between the nozzle body and the nozzle insertion hole has a pressure reducing effect. That is, it is possible to maintain high sealing performance while having a simple sealing structure having the above-mentioned volume portion. As a result, the number of parts can be reduced, such as by eliminating the double gasket structure.

On the other hand, in such a fuel injection device, since the tip of the nozzle body is usually directly exposed to the combustion gas, an excessive temperature rise of the nozzle body itself is required to maintain the fuel injection accuracy. Although this is a factor that cannot be ignored, according to the same configuration in which the volume is provided between the nozzle body and the nozzle insertion hole, the cooling effect of the nozzle body can be obtained together with the expansion of the heat radiation area.

On the other hand, in such a fuel injection device for in-cylinder direct injection, carbon or the like generated by combustion adheres and accumulates between the nozzle body and the nozzle insertion hole, and the fuel injection means is mounted on the engine head. Tend to stick to the surface. That is, in many cases, the fuel injection means cannot be easily removed from the engine head during maintenance and inspection. In this regard, according to the same configuration in which the volume is provided between the nozzle body and the nozzle insertion hole, the fixing area is also reduced, and the effect of preventing or suppressing the fixing of the fuel injection means is also obtained. .

[0014] According to the second aspect of the present invention, the first aspect is provided.
In the fuel injection device for an engine described in the above, the volume is defined as a circumferential groove provided on an outer peripheral surface of the nozzle body, and the device is configured.

According to the second aspect of the present invention, the volume can be formed relatively easily, the above-described effect of reducing the combustion gas, the effect of cooling the nozzle body, and the fuel injection. The effect of preventing or suppressing the sticking of the means can be obtained accurately.

According to the third aspect of the present invention, the first aspect of the present invention is provided.
In the fuel injection device for an engine according to the present invention, the volume is defined as a peripheral groove provided on an inner peripheral surface of the nozzle insertion hole.

According to the third aspect of the present invention, the above-described effect of reducing the pressure of the combustion gas, the effect of cooling the nozzle body, and the effect of preventing or suppressing the sticking of the fuel injection means can be accurately obtained. In addition, in the case of the same configuration in which a volume is provided on the inner peripheral surface of the nozzle insertion hole, that is, on the engine head side, it is easy to secure a larger volume as the volume. An even greater effect can be expected as an effect of preventing or suppressing the sticking of the means.

According to the fourth aspect of the present invention, there is provided the second aspect.
4. The fuel injection device for an engine according to claim 3, wherein the volume portion includes a plurality of circumferential grooves defined in an axial direction of the nozzle body.

According to this structure, the above-described depressurizing effect on the high-pressure combustion gas generated in the combustion chamber is repeatedly provided by the plurality of circumferential grooves defined in the axial direction of the nozzle body. As a result, a greater effect can be obtained as the decompression effect. Further, according to the configuration, the plurality of circumferential grooves partitioned in the axial direction of the nozzle body can further increase the heat radiation area, and the cooling effect of the nozzle body can be further enhanced. When a plurality of circumferential grooves partitioned in the axial direction of the nozzle body are provided in a manner that contributes to a reduction in the total area of the fixing area,
The effect of preventing or suppressing the sticking of the fuel injection means can be further enhanced.

According to the fifth aspect of the present invention, in the fourth aspect,
In the fuel injection device for an engine according to the present invention, the plurality of circumferential grooves forming the volume portion are formed as grooves whose volume sequentially decreases from those near to the combustion chamber to those far from the combustion chamber. Constitute.

According to the fifth aspect of the present invention, the above-described depressurizing effect on the high-pressure combustion gas generated in the combustion chamber is initially provided largely by the groove having a relatively large volume, and thereafter, it is sequentially increased. Smaller volumes are provided sequentially by smaller volumes. Normally, the pressure of the combustion gas leaking from the gap (clearance) between the nozzle body and the nozzle insertion hole gradually decreases each time the pressure-reducing effect is imparted with the propagation in the axial direction of the nozzle body. Therefore, such a configuration makes it possible to obtain a greater decompression effect more efficiently.

Incidentally, the plurality of circumferential grooves have the same volume, and the plurality of circumferential grooves are sequentially arranged from the one near the combustion chamber to the one distant from the combustion chamber. Even if the total volume as the volume part is the same as that of the groove formed to have a smaller volume, the mode of imparting the depressurizing effect is different. That is, in view of the transition of the pressure of the combustion gas in the axial direction of the nozzle body, a large pressure-reducing effect is first provided by the groove having a relatively large volume, and thereafter, the smaller pressure is gradually reduced by the groove having a smaller volume. The structure of the invention according to claim 5, wherein the decompression effect is provided,
These decompression effects can be used more effectively.

In other words, the same configuration of the invention described in claim 5 can be said to be a configuration in which the maximum decompression effect can be obtained through a volume portion having only a limited volume. The volume of each groove forming the volume portion is determined by the groove width and height of the groove, but basically, as long as each volume is determined in the above-described mode,
Either the groove width or the height may be adjusted.

[0024]

1 and 2 show one embodiment of a fuel injection device for an engine according to the present invention. In this embodiment, the fuel injection device is applied to a direct injection type gasoline engine.

First, an outline of a fuel injection device according to the embodiment will be described with reference to FIG. As shown in FIG. 1, the engine 10 is configured to have a cylinder block 11 and a cylinder head (engine head) 12 as a support of each part thereof.

The cylinder block 11 has a cylinder bore 11B formed therein.
The piston 20 moves up and down in B according to each process of intake, compression, combustion (explosion), and exhaust of the engine 10. The space above the piston 20 is a combustion chamber 30 of the engine 10.

An intake port 13 and an exhaust port 14 are formed in the cylinder head 12, respectively. The intake port 13 is opened and closed by an intake valve 41, and the exhaust port 14 is opened and closed by an exhaust valve 42 according to the intake, compression, combustion (explosion), and exhaust strokes of the engine 10.

On the other hand, in the vicinity of the intake port 13 of the cylinder head 12, a nozzle insertion hole 12N and an injector mounting hole 12H are formed so as to penetrate the combustion chamber 30, and the fuel injector is formed through these holes 12N and 12H. 50 are mounted. The injector 50 has a configuration shown in FIG. 1 in which the nozzle body 52 is inserted into the nozzle insertion hole 12N and the cylinder screw 51 is screwed into a corresponding screw hole of the injector mounting hole 12H. It is mounted on the cylinder head 12. Note that in FIG.
Reference numerals 2D1 and 12D2 denote first and second step portions formed between the nozzle insertion hole 12N and the injector mounting hole 12H of the cylinder head 12, respectively.

In the fuel injection device of the embodiment,
Thus, the tip of the nozzle body 52 is
The fuel injector 50 is mounted on the cylinder head (engine head) 12 so as to be exposed in the combustion chamber 30, and the fuel is directly injected into the combustion chamber 30 from the exposed end of the nozzle body 52. . The combustible air-fuel mixture locally formed in the combustion chamber 30 by the direct injection of the fuel is also supplied to the cylinder head 12.
The spark plug 6 provided in the mode shown in FIG.
Combustion is caused by ignition of 0.

FIG. 2 is a sectional view of the fuel injection device of this embodiment, in particular, a region Z surrounded by a broken line in FIG. 1, that is, a nozzle insertion hole 12N and a nozzle insertion hole 12N formed in the cylinder head 12. 2 is an enlarged view showing a detailed structure of the nozzle body 52 of the fuel injector 50 inserted in the fuel injector 50. Next, with reference to FIG. The structures of the insertion hole 12N and the nozzle body 52 will be described in more detail.

As shown in FIG. 2, fuel is injected into the combustion chamber 30 at the tip of the fuel injector 50 facing the combustion chamber 30 of the nozzle body 52 in the above-described manner. Injection hole 53 is provided. As is well known, injection and stop of fuel injection are controlled by opening and closing the needle valve.

On the other hand, as shown in FIG. 2, the nozzle body 52 of the fuel injector 50 has a plurality of (four in the embodiment) circumferential grooves 52a, 52.
b, 52c and 52d are formed. These circumferential grooves 52
a, 52b, 52c, and 52d are all the nozzle insertion holes 12N of the nozzle body 52 and the cylinder head 12.
And a volume portion is formed between the grooves 52a, 52b, 52c, and 52d.
Are set to "Ta", "Tb", "Tc", "T
d ”, and the groove heights are“ Ba ”and“ B ”, respectively.
b>, “Bc”, “Bd” and their groove volumes as “Va”, “Vb”, “Vc”, “Vd”, Ta>Tb>Tc>TdBa>Bb>Bc> Bd The volume portion is formed in a relationship of Va>Vb>Vc> Vd. That is, in this embodiment, each of the circumferential grooves 52a, 52b, 52c, and 52d forming the same volume portion is a groove whose volume decreases sequentially from the one near the combustion chamber 30 to the one farther from the combustion chamber 30. Has formed.

The volume portion formed in this manner operates in the fuel injection device for in-cylinder direct injection as in the embodiment and operates as follows. As described above, the fuel injection device for in-cylinder direct injection has a structure in which the tip end portion of the nozzle body 52 is exposed to the combustion chamber 30 of the engine. Combustion gas must also be reliably sealed, and its sealing structure naturally requires high sealing performance. In this regard, the nozzle body 52 and the nozzle insertion hole 1
By forming a volume between the nozzle body 2N and the high pressure combustion gas generated in the combustion chamber 30 and leaking from a gap (clearance) C between the nozzle body 52 and the nozzle insertion hole 12N. A decompression effect can be provided, and the sealing performance can be maintained.

By providing a plurality of circumferential grooves defined in the axial direction of the nozzle body 52 as the volume, the pressure of the combustion gas leaking from the clearance (clearance) C is reduced. As the pressure-reducing effect is imparted in accordance with the propagation of 52 in the axial direction, it gradually decreases. Therefore, as described above, each of the plurality of circumferential grooves 52a, 52b, and 52 has a volume gradually decreasing from one near the combustion chamber 30 to one farther from the combustion chamber 30.
By forming them as c and 52d, a greater decompression effect can be obtained more efficiently. That is, the peripheral groove 52a having a relatively large volume first provides a large depressurizing effect, and thereafter, the peripheral grooves 52b to 52d each having a smaller volume sequentially provide a small depressurizing effect. Is the first stepped portion 1 between the nozzle insertion hole 12N and the injector mounting hole 12H.
By the time the gasket 54 provided on the 2D1 is reached, its pressure is also reduced to a sufficiently small pressure.

Incidentally, in such a conventional fuel injection device for in-cylinder direct injection, a washer or a gasket is also used for the second step 12D2 (see FIG. 1) between the nozzle insertion hole 12N and the injector mounting hole 12H. Although it was necessary to provide a seal, the provision of the above-mentioned volume portion makes it possible to reduce the number of components such as omitting the seal to the second step portion 12D2.

On the other hand, in such a fuel injection device for in-cylinder direct injection, the tip of the nozzle body 52 is usually directly exposed to the combustion gas. An excessive rise in temperature of the body 52 itself is also a factor that cannot be ignored. In this regard, the nozzle body 52
By providing the volume in the above-described manner between the nozzle body and the nozzle insertion hole 12N, the heat radiation area is enlarged, and the cooling effect of the nozzle body 52 can also be obtained.

On the other hand, particularly in such a fuel injection device for in-cylinder direct injection, carbon or the like generated by combustion adheres and accumulates in a gap (clearance) C between the nozzle body 52 and the nozzle insertion hole 12N. Therefore, the fuel injector 50 tends to adhere to the cylinder head 12. That is, even if the injector 50 is to be removed from the cylinder head 12 during maintenance and inspection,
Often it cannot be easily removed. In this regard, by providing the volume in the above-described manner between the nozzle body 52 and the nozzle insertion hole 12N, the fixed area is also reduced,
The effect of preventing or suppressing the sticking of the injector 50 can also be obtained.

In addition, the fuel injection device of the same embodiment is provided with a volume portion in the above-described manner, and the combustion gas is positively guided to the volume portion from a gap (clearance) C between the nozzle body 52 and the nozzle insertion hole 12N. In this case, since the gap (clearance) C between the nozzle body 52 and the nozzle insertion hole 12N can be set relatively large, the productivity of the fuel injector 50 and the cylinder head 12 can be improved. In addition, the nozzle body 52
The peripheral grooves 52a, 5b provided on the outer peripheral surface of the
2b, 52c and 52d themselves can be easily processed.

As described in detail above, according to the fuel injection device of this embodiment, many excellent effects as listed below can be obtained. (1) Since a volume is formed between the nozzle body 52 and the nozzle insertion hole 12N, the volume is generated in the combustion chamber 30 and the gap (clearance) C between the nozzle body 52 and the nozzle insertion hole 12N is reduced. The high-pressure combustion gas to be leaked can be provided with a decompression effect. That is, it is possible to maintain high sealing performance while having a simple sealing structure having a volume portion.

(2) In addition, since this volume portion is formed as the circumferential grooves 52a, 52b, 52c, and 52d whose volumes decrease gradually from those near the combustion chamber 30 to those far from the combustion chamber 30, a greater decompression effect can be obtained. It can be obtained efficiently. In other words, the maximum depressurizing effect can be obtained through the volume having only a limited volume.

(3) Since the sealing structure is capable of obtaining such a high pressure reducing effect, the second stepped portion 12
It is also possible to reduce the number of parts, for example, to omit the seal for D2 (FIG. 1).

(4) Nozzle body 52 and nozzle insertion hole 1
2N, the nozzle body 5
2, the heat radiation area is enlarged, and the cooling effect of the nozzle body 52 is also obtained.

(5) Similarly, by forming a volume between the nozzle body 52 and the nozzle insertion hole 12N, the fixed area of the nozzle body 52 is also reduced, and the effect of preventing or suppressing the fuel injector 50 from being fixed is also improved. Obtained together.

(6) Nozzle body 52 and nozzle insertion hole 1
Since the gap (clearance) C between the fuel injector 2 and 2N can be set relatively large, the productivity of the fuel injector 50 and the cylinder head 12 can be increased.

(7) The above-mentioned peripheral grooves 52a, 52b, 52c, 5c provided on the outer peripheral surface of the nozzle body 52 as its volume.
2d is also easy to process. It should be noted that the fuel injection device according to the present invention is not limited to the above-described embodiment, but may be realized by appropriately modifying the embodiment, for example, as follows.

In the above embodiment, the peripheral grooves 52a, 52b, 5
2c and 52d are provided, but as shown in FIG. 3 corresponding to FIG. 2 above, that is, as an enlarged view of the area Z in FIG. 1, the inner circumference of the nozzle insertion hole 12N of the cylinder head (engine head) 12 is shown. Circumferential grooves 12a, 12
It is good also as a structure provided with b, 12c, and 12d. Also in this case, the groove widths of the circumferential grooves 12a, 12b, 12c, and 12d are set to “Ta ′”, “Tb ′”, “Tc ′”,
"Td '", and their groove heights are "Ba'",
"Bb '", "Bc'", "Bd '", and their groove volumes are "Va'", "Vb '", "Vc'", "V
d '", this volume is formed in the following relationship: Ta'> Tb '>Tc'>Td'Ba'>Bb'> Bc '>Bd'Va'> Vb '>Vc'> Vd ' Thereby, the effect according to the above embodiment can be obtained.

In the embodiment illustrated in FIG. 2 or the embodiment illustrated in FIG. 3, the peripheral grooves 52a, 52b, 52c, 52d or the peripheral grooves 12a, The volumes of the grooves 12b, 12c, and 12d are determined by the groove width and the groove height of the grooves. As long as the volume is determined, either the groove width or the groove height may be adjusted. That is, the circumferential grooves 52a, 52b, 52c, 52d
As for (FIG. 2), the groove width does not need to be Ta>Tb>Tc> Td or the groove height is Ba>Bb>Bc> Bd as long as the relation Va>Vb>Vc> Vd for the volume is satisfied. And the circumferential grooves 12a, 12b, 12
Also for c and 12d (FIG. 3), as long as the relationship of Va '>Vb'> Vc '>Vd' for the volume is satisfied, the groove width is Ta '>Tb'> Tc '>Td' or the groove height is Ba. It is not necessary that '>Bb'> Bc '>Bd'. By determining the volumes of the circumferential grooves at least in such a manner, the effect (2) can be obtained.

Particularly, when a circumferential groove is provided on the inner peripheral surface of the nozzle insertion hole 12N as in the embodiment illustrated in FIG. 3, a larger volume is secured as the same volume. For this reason, a larger volume portion may be formed by setting the groove height larger. In this case, even greater effects can be expected as the above-described depressurizing effect and cooling effect. In addition, when the expansion of the volume is performed in a manner that also contributes to a reduction in the total area of the fixed area, the effect of preventing or suppressing the fuel injector 50 from being fixed is further enhanced.

In the embodiment illustrated in FIG. 2, FIG.
In the embodiment illustrated in FIG.
2a, 52b, 52c, 52d or the circumferential groove 12a,
Although the volumes of 12b, 12c, and 12d are determined in such a manner that the volumes are gradually reduced from those closer to the combustion chamber 30 to those farther from the combustion chamber 30, the volumes of the respective circumferential grooves may all be the same. In short, the nozzle body 5
If a plurality of circumferential grooves partitioned in the axial direction are provided, the pressure reducing effect on the high-pressure combustion gas generated in the combustion chamber 30 is reduced by the plurality of circumferential grooves partitioned in the axial direction of the nozzle body 52. Since it is repeatedly applied, a great effect can be expected as the decompression effect. In addition, even with such a volume portion, the heat dissipation area can be increased by the plurality of circumferential grooves partitioned in the axial direction of the nozzle body 52, and the cooling effect of the nozzle body 52 can be sufficiently expected. When a plurality of circumferential grooves defined in the axial direction of the nozzle body 52 are provided in a manner that also contributes to a reduction in the total area of the fixing area, the effect of preventing or suppressing the fixing of the fuel injector 50 is also obtained. A sufficiently large effect can be expected.

The number of circumferential grooves forming the volume is arbitrary. In particular, when one groove is used as the same volume, the following configuration can be changed. (A) As shown in FIG. 4 corresponding to FIG. 2, that is, as an enlarged view of the area Z in FIG. 1, a male screw 52e is cut on the outer peripheral surface of the nozzle body 52, and the screw groove and the nozzle insertion hole 1 are formed.
A configuration in which the space Vx formed between the space and the 2N is a volume.

(A) As shown in FIG. 5 as an enlarged view of the area Z in FIG. 1, a female screw 12e is formed on the inner peripheral surface of the nozzle insertion hole 12N and formed between the screw groove and the nozzle body 52. A space Vx ′ to be used as a volume.

According to the configuration (A) or (A), it is possible to obtain substantially the same effects as in the above embodiment. Moreover, according to the configuration (A) or (A), the processing for forming the above-mentioned volume portion is further facilitated. In these configurations (A) and (A), the male screw 52e or the female screw 1
It is necessary to cut 2e so as not to reach the combustion chamber 30 in order to ensure the above-described depressurizing effect.

In each of the embodiments illustrated in FIGS. 2 to 5, the volume is provided only on one of the outer peripheral surface of the nozzle body 52 and the inner peripheral surface of the nozzle insertion hole 12N. However, the same volume portion may be provided on both the outer peripheral surface of the nozzle body 52 and the inner peripheral surface of the nozzle insertion hole 12N.

In addition, the shape of the volume portion is not limited to the circumferential groove and the like, and is arbitrary. Whatever the shape, the point is,
What is necessary is just to form a concave space in at least one of the outer peripheral surface of the nozzle body 52 and the inner peripheral surface of the nozzle insertion hole 12N. In addition, the present invention is similarly applied to a fuel injection device having a fuel injection nozzle for direct injection in a cylinder as a fuel injection means in a diesel engine as well as a gasoline engine of a direct injection type. be able to.

Finally, technical ideas other than the claims that can be grasped by the above-described embodiment will be described below together with their effects. (1) The fuel injection device for an engine according to claim 1, wherein the volume portion is a thread groove provided on an outer peripheral surface of the nozzle body.

(2) The fuel injection device for an engine according to claim 1, wherein the volume portion is a screw groove provided on an inner peripheral surface of the nozzle insertion hole.

According to the configuration described in (1) or (2), the fuel injection means (fuel injector, fuel injection nozzle) is formed between the nozzle body and the nozzle insertion hole when the fuel injection means is mounted on the engine head. The high-pressure combustion gas that is generated in the combustion chamber and leaks from the gap (clearance) between the nozzle body and the nozzle insertion hole can provide a decompression effect. In other words, high sealing performance can be maintained while having a simple sealing structure, and the number of parts can be reduced, such as by eliminating the double gasket structure.

Also in this case, the heat radiation area of the nozzle body is enlarged, the cooling effect of the nozzle body is obtained, and the fixing area of the nozzle body is also reduced. Can also be obtained at the same time.

In this case, the processing for forming the above-mentioned volume is also easy.

[0060]

According to the present invention, when the fuel injection means is mounted on the engine head, a volume formed between the nozzle body and the nozzle insertion hole is generated in the combustion chamber. The high-pressure combustion gas leaking from the gap (clearance) between the nozzle body and the nozzle insertion hole is given a decompression effect. That is,
It is possible to maintain high sealing performance while having a simple sealing structure having a volume portion. As a result, the number of parts can be reduced, such as by eliminating the double gasket structure.

On the other hand, the volume provided between the nozzle body and the nozzle insertion hole increases the heat radiation area of the nozzle body, and the cooling effect of the nozzle body can be obtained.

On the other hand, the volume provided between the nozzle body and the nozzle insertion hole reduces the fixing area of the nozzle body, so that the effect of preventing or suppressing the fixing of the fuel injection means can be obtained. become.

According to the second aspect of the present invention, the volume can be formed relatively easily.
The effect of reducing the pressure of the combustion gas, the effect of cooling the nozzle body, and the effect of preventing or suppressing the sticking of the fuel injection means can be accurately obtained.

According to the third aspect of the present invention, the effect of reducing the pressure of the combustion gas, the effect of cooling the nozzle body, and the effect of preventing or suppressing the sticking of the fuel injection means can be accurately obtained. In the case of the present invention in which a volume is provided on the inner peripheral surface of the nozzle insertion hole, that is, on the engine head side,
Since it is easy to secure a larger volume as the volume portion, it is possible to expect a greater effect as the pressure reducing effect, the cooling effect, and the effect of preventing or suppressing the sticking of the fuel injection means.

According to the fourth aspect of the present invention, the pressure reducing effect on the high-pressure combustion gas generated in the combustion chamber is repeatedly provided by the plurality of circumferential grooves partitioned in the axial direction of the nozzle body. A larger effect can be obtained as an effect. Further, according to the invention, the heat dissipation area is further enlarged by the plurality of circumferential grooves partitioned in the axial direction of the nozzle body, and the cooling effect of the nozzle body is further enhanced. When a plurality of circumferential grooves defined in the axial direction of the nozzle body are provided in a manner contributing to a reduction in the total area of the fixing area, the effect of preventing or suppressing the fixing of the fuel injection means is further enhanced. Become like

According to the fifth aspect of the present invention, the effect of reducing the pressure of the high-pressure combustion gas generated in the combustion chamber is firstly increased by the groove having a relatively large volume. The grooves are sequentially provided in smaller sizes. That is, a greater pressure reduction effect can be obtained more efficiently.

[Brief description of the drawings]

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

FIG. 2 is an enlarged side view and a cross-sectional view showing a region Z in FIG. 1;

FIG. 3 is a side view and a sectional view showing another embodiment of the fuel injection device according to the present invention as an enlarged view corresponding to a region Z in FIG. 1;

FIG. 4 is a side view and a cross-sectional view showing still another embodiment of the fuel injection device according to the present invention as an enlarged view corresponding to a region Z in FIG. 1;

5 is a side view and a sectional view showing an enlarged view corresponding to a region Z of FIG. 1 according to still another embodiment of the fuel injection device according to the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Cylinder block, 11B ... Cylinder bore, 12 ... Cylinder head (engine head), 12H ... Injector mounting hole, 12N ... Nozzle insertion hole, 12a-12d ... Peripheral groove, 12e ... Female screw, 13 ...
Intake port, 14 ... exhaust port, 20 ... piston, 30
... combustion chamber, 41 ... intake valve, 42 ... exhaust valve, 50
... Fuel injector, 51 ... Cylinder screw, 52 ... Nozzle body, 52a-52d ... Circumferential groove, 52
e: male screw, 53: injection hole, 54: gasket, 60: spark plug.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masanori Sugiyama 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G024 AA04 BA21 BA29 CA19 DA01 DA02 FA00 FA08 FA14 GA10 GA25 3G066 AA02 AA05 AA07 AB02 AD12 BA00 BA53 BA55 BA61 BA65 CC01 CD04 CD10 CD23

Claims (5)

[Claims] A fuel injection means mounted on a nozzle insertion hole of an engine head so that a nozzle body is inserted into the nozzle insertion hole; An engine fuel injection device for directly injecting fuel into an engine, characterized in that a volume portion forming a concave space is provided on at least one of an outer peripheral surface of the nozzle body and an inner peripheral surface of the nozzle insertion hole. Injection device. 2. The fuel injection device for an engine according to claim 1, wherein said volume portion is a circumferential groove provided on an outer peripheral surface of said nozzle body. 3. The fuel injection device for an engine according to claim 1, wherein the volume portion is a circumferential groove provided on an inner circumferential surface of the nozzle insertion hole. 4. The fuel injection device for an engine according to claim 2, wherein said volume portion comprises a plurality of circumferential grooves defined in an axial direction of said nozzle body. 5. The fuel injection device for an engine according to claim 4, wherein the plurality of circumferential grooves forming the volume portion are formed as grooves whose volume decreases sequentially from a portion closer to the combustion chamber to a portion farther from the combustion chamber. A fuel injection device for an engine, comprising: