Fuel injection valve for an internal combustion engine

The disclosure of Japanese Patent Application No. HEI 9-310500 filed on Nov. 12, 1997 (the convention application: Japanese Patent Application No. HEI 9-167629 with a priority date of Jun. 24, 1997) including the specification, drawings and abstract is incorporated herein by reference in its entirety.

The present invention relates to a fuel injection valve for an internal combustion engine.

Conventionally known fuel injection valves for an internal combustion engine have been provided with nozzle holes whose hole axes form a predetermined angle with a plane perpendicular to a central axis of a valve body. This type of fuel injection valve is disclosed, for example, in Japanese Patent Application Laid-Open No. HEI 7-127550. Based on this art wherein a fuel jet adjusting plate has nozzle holes of which all the hole axes form a predetermined angle with the plane perpendicular to the central axis the nozzle holes may be arranged along two circles or more coaxial with the central axis.

FIG. 16 is a partial plan view of a conventional fuel injection valve for an internal combustion engine, illustrating the fuel jet adjusting plate where, based on the aforementioned art, the nozzle holes are arranged along two circles coaxial with the central axis. Referring to FIG. 16 , reference characters H 1 ′ to H 12 ′ denote nozzle holes, C 1 ′ a first circle coaxial with the valve body and along which the nozzle holes H 1 ′ to H 8 ′ are arranged. C 2 ′ a second circle coaxial with the valve body and along which the nozzle holes H 9 ′ to H 12 ′ are arranged, and L 0 ′ the central axis. The second circle C 2 ′ has a diameter smaller than that of the first circle C 1 ′. FIG. 17 is a sectional view taken along line XVII—XVII in FIG. 16 . In FIG. 17 , a plane perpendicular to the central axis L 0 ′ is defined as a reference plane SB′. A cross section shown in FIG. 17 consists of a plane S 0 ′ perpendicular to the reference plane SB′ and including the central axis L 0 ′, a plane S 10 ′ perpendicular to the reference plane SB′ and including a hole axis L 10 ′ of the nozzle hole H 10 ′, and a plane S 3 ′ perpendicular to the reference plane SB′ and including a hole axis L 3 ′ of the nozzle hole H 3 ′. Referring to FIG. 17 , reference characters F 10 ′, F 3 ′ denote fuel sprays injected through the nozzle holes H 10 ′, H 3 ′ respectively. The hole axis L 3 ′ forms an acute angle a 3 ′ with the reference plane SB′, and the hole axis L 10 ′ forms an acute angle a 10 ′ with the reference plane SB′. As can be seen from FIG. 17 , the acute angle a 3 ′ is equal to the acute angle a 10 ′. Although not shown, hole axes L 1 ′ to L 12 ′ form acute angles a 1 ′ to a 12 ′ respectively, with the reference plane SB′ and all these acute angles a 1 ′ to a 12 ′ assume an equal value.

As illustrated in FIG. 17 , however, the fuel sprays F 3 ′, F 10 ′ injected through the nozzle holes H 3 ′, H 10 ′ are diffused and thus interfere with each other. In this case, the fuel sprays F 3 ′, F 10 ′ become unstable, which makes it impossible to suitably atomize injected fuel.

The present invention has been devised in consideration of the aforementioned problems. It is thus an object of the present invention to provide a fuel injection valve for an internal combustion engine that is capable of preventing fuel sprays injected through nozzle holes arranged along a plurality of concentric circles from interfering with each other, thereby stabilizing the respective fuel sprays, and suitably atomizing the injected fuel.

In order to achieve the aforementioned object, a first aspect of the present invention provides a fuel injection valve for an internal combustion engine including a valve body driven by driving means between an open position and a closed position, a fuel jet adjusting plate for atomizing fuel injected when the valve body assumes the open position, a plurality of first nozzle holes arranged along a first circle that is located on the fuel jet adjusting plate and coaxial with a central axis of the valve body, and a plurality of second nozzle holes arranged along a second circle concentric with the first circle and having a diameter larger than that of the first circle, wherein each hole axis of the second nozzle holes forms second acute angle with a plane perpendicular to the central axis and each hole axis of the first nozzle holes forms a first acute angle with the plane perpendicular to the central axis which is larger than the second acute angle.

In a second aspect of the present invention, the fuel injection valve according to the first aspect may be provided in an intake port in order to inject and atomize fuel such that the fuel reaches a combustion chamber at a timing at which an intake valve assumes its open position. In this case, fuel sprays injected through the first and second nozzle holes do not reach a central portion of a mushroom-shaped portion of the intake valve but only an outer periphery of the mushroom-shaped portion.

In a third aspect of the present invention, the fuel injection valve according to the second aspect may be constructed such that the first nozzle holes have an opening area different from that of the second nozzle holes.

According to the first aspect of the present invention, the hole axis of the second nozzle holes form an acute angle with the plane perpendicular to the central axis of the valve body which is smaller than that formed by the hole axes of the first nozzle holes with the aforementioned plane. Thus, the fuel sprays injected through the second nozzle holes can be directed away from the fuel sprays injected through the first nozzle holes. In this case, it is possible to prevent the fuel sprays injected through the second nozzle holes from interfering with the fuel sprays injected through the first nozzle holes. As a result, the respective fuel sprays can be stabilized, which makes it possible to suitably atomize injected fuel.

According to the second aspect of the present invention, since the fuel injected from the fuel injection valve does not adhere to the central portion of the mushroom-shaped portion of the intake valve, no delay is caused in supplying fuel to the combustion chamber. Hence, it is possible to improve response in a transient operating state of an internal combustion engine.

According to the third aspect of the present invention, the fuel injection valve can be constructed, if necessary, such that the first nozzle holes have an opening area different from that of the second nozzle holes. Thus, fuel entering the combustion chamber can be suitably distributed, whereby it is possible to make air-fuel mixture homogeneous, preclude incomplete combustion by less densely distributing fuel on the side of an ignition plug, or causing lean fuel to burn by more densely distributing fuel on the side of the ignition plug.

Further objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein:

FIG. 1 is a partial plan view of a fuel jet adjusting plate of a fuel injection valve for an internal combustion engine according to a first embodiment of the present invention, illustrating a section where nozzle holes are formed;

FIG. 2 is a sectional view taken along line II—II in FIG. 1 ;

FIG. 3 is a projected view illustrating hole axes L 5 , L 4 of nozzle holes H 5 , H 4 projected onto a plane SY;

FIG. 4 is a projected view illustrating hole axes L 11 , L 10 of nozzle holes H 11 , H 10 projected onto the plane SY;

FIG. 5 is a projected view illustrating hole axes L 6 , L 3 of nozzle holes H 6 , H 3 projected onto the plane SY;

FIG. 6 is a projected view illustrating hole axes L 2 , L 3 of nozzle holes H 2 , H 3 projected onto a plane SX;

FIG. 7 is a projected view illustrating hole axes L 9 , L 10 of nozzle holes H 9 , H 10 projected onto the plane SX;

FIG. 8 is a projected view illustrating hole axes L 1 , L 4 of nozzle holes H 1 , H 4 projected onto the plane SX;

FIG. 9 is a schematic view illustrating a relationship between the nozzle holes formed in a fuel jet adjusting plate of a first embodiment and fuel sprays injected therethrough;

FIG. 10 is a sectional view similar to FIG. 2 according to a second embodiment of the present invention;

FIG. 11 is a partial side sectional view of the fuel injection valve for an internal combustion engine according to a third embodiment of the present invention;

FIG. 12 is schematic view similar to FIG. 9 as viewed as indicated by an arrow in FIG. 11 ;

FIG. 13 is a schematic view similar to FIG. 12 illustrating the fuel injection valve for an internal combustion engine according to a fourth embodiment of the present invention;

FIG. 14 is a schematic view similar to FIG. 12 illustrating the fuel injection valve for an internal combustion engine according to a fifth embodiment of the present invention;

FIG. 15 is a schematic view similar to FIG. 12 illustrating the fuel injection valve for an internal combustion engine according to a sixth embodiment of the present invention;

FIG. 16 is a partial plan view of a fuel jet adjusting plate of a conventional fuel injection plate for an internal combustion engine; and

FIG. 17 is a sectional view taken along line XVII—XVII in FIG. 11 .

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a partial plan view of a fuel jet adjusting plate of a fuel injection valve for an internal combustion engine according to a first embodiment of the present invention, illustrating a section where nozzle holes are formed. Referencing to FIG. 1 , reference characters H 1 to H 12 denote nozzle holes, C 1 a first circle coaxial with a valve body, C 2 a second circle also coaxial with the valve body and having a diameter smaller than that of the first circle C 1 ′, L 0 a central axis of the valve body. As illustrated in FIG. 1 , the nozzle holes H 1 to H 8 are arranged along the first circle C 1 at predetermined intervals and the nozzle holes H 9 to H 12 are arranged along the second circle C 2 at predetermined intervals.

FIG. 2 is a sectional view taken along line II—II in FIG. 1 . In FIG. 2 , a plane perpendicular to the central axis L 0 of the valve body is defined as a reference plane SB. As can be seen from FIGS. 1 and 2 , a cross section shown in FIG. 2 consists of a plane S 0 that is perpendicular to the reference plane SB and includes the central axis L 0 , a plane S 10 that is perpendicular to the reference plane SB and includes a hole axis L 10 of the nozzle hole H 10 , and a plane S 3 that is perpendicular to the reference plane SB and includes a hole axis L 3 of the nozzle hole H 3 . A fuel jet adjusting plate 1 has the shape of a slab. The valve body (not shown) disposed upstream of the fuel jet adjusting plate 1 is driven by driving means (not shown) between an open position and a closed position. When the valve body is opened, the fuel jet adjusting plate 1 atomizes fuel injected through the nozzle holes H 1 to H 12 .

In this embodiment, hole axis L 1 to L 8 of the nozzle holes H 1 to H 8 form acute angles a 1 to a 8 respectively, with the reference plane SB and hole axes L 9 to L 12 of the nozzle holes H 9 to H 12 form acute angles a 9 to a 12 , respectively with the reference plane SB. Although FIG. 2 illustrates only the acute angles a 3 and a 10 , the acute angle a 1 to a 8 are also smaller than the acute angles a 9 to a 12 . Thus, fuel sprays F 1 to F 8 injected through the nozzle holes H 1 to H 8 and fuel sprays F 9 to F 12 injected through the nozzle holes H 9 to H 12 are directed away from each other. Therefore, the fuel sprays F 1 to F 8 injected through the nozzle holes H 1 to H 8 do not interfere with the fuel sprays F 9 to F 12 injected through the nozzle holes H 9 to H 12 . As a result, it is possible to stabilize the respective fuel sprays and suitably atomize the fuel thus injected. In addition, despite the fact fuel pressures near inlet portions of the nozzle holes H 1 to H 8 are lower than fuel pressures near inlet portions of the nozzle holes H 9 to H 12 , the fuel sprays F 1 to F 8 injected through the nozzle holes H 1 to H 8 can suitably be atomized. This is because the acute angles a 1 to a 8 are smaller than the acute angles a 9 to a 12 .

FIG. 3 is a projected view illustrating the hole axes L 5 , L 4 of the nozzle holes H 5 , H 4 projected onto a plane SY (FIG. 1 ). FIG. 4 is a projected view illustrating the hole axes L 11 , L 10 of the nozzle holes H 11 , H 10 projected onto the plane SY, and FIG. 5 is a projected view illustrating the hole axes L 6 , L 3 of the nozzle holes H 6 , H 3 projected onto the plane SY. FIG. 6 is a projected view illustrating the hole axes L 2 , L 3 of the nozzle holes H 2 , H 3 projected onto a plane SX (FIG. 1 ). FIG. 7 is a projected view illustrating the hole axes L 9 , L 10 of the nozzle holes H 9 , H 10 projected onto the plane SX, and FIG. 8 is a projected view illustrating the hole axes L 1 , L 4 of the nozzle holes H 1 , H 4 projected onto the plane SX. Referring now to FIGS. 3 through 8 , respective acute angles will be defined as follows. The hole axis L 5 projected onto the plane SY forms with the reference plane SB an acute angle aY 5 , the hole axis L 4 projected onto the plane SY forms with the reference plane SB an acute angle aY 4 , the hole axis L 11 projected onto the plane SY forms with the reference plane SB an acute angle aY 11 , the hole axis L 10 projected onto the plane SY forms with the reference plane SB an acute angle aY 10 , the hole axis L 6 projected onto the plane SY forms with the reference plane SB an acute angle aY 6 , and the hole axis L 3 projected onto the plane SY forms with the reference plane SB an acute angle aY 3 . The hole axis L 2 projected onto the plane SX forms with the reference plane SB an acute angle aX 2 , the hole axis L 3 projected onto the plane SX forms with the reference plane SB an acute angle aX 3 , the hole axis L 9 projected onto the plane SX forms with the reference plane SB an acute angle aX 9 , the hole axis L 10 projected onto the plane SX forms with the reference plane SB an acute angle aX 10 , the hole axis L 1 projected onto the plane SX forms with the reference plane SB an acute angle aX 1 , and the hole axis L 4 projected onto the plane SX forms with the reference plane SB an acute angle aX 4 .

Since the fuel jet adjusting plate 1 of this embodiment is employed in an internal combustion engine of two intake valve type, the following relationships are established among the aforementioned acute angles: aY 5 =aY 4 <aY 11 =aY 10 <aY 6 =aY 3 ; and aX 9 =aX 10 <aX 2 =aX 3 <aX 1 =aX 4 . That is, as illustrated in FIG. 9 , the fuel sprays F 7 , F 12 , F 8 , F 1 , F 9 and F 2 correspond to intake air sucked through one intake valve, and the fuel sprays F 6 , F 11 , F 5 , F 4 , F 10 and F 3 correspond to intake air sucked through the other intake valve. FIG. 9 is a schematic view illustrating a relationship between the nozzle holes formed in the fuel jet adjusting plate of the first embodiment and the fuel sprays injected therethrough.

FIG. 10 is a sectional view similar to FIG. 2 according to a second embodiment of the present invention. As can be seen from FIG. 10 , the fuel jet adjusting plate 1 of this embodiment has the shape of a bowl. As with the first embodiment, the acute angle a 3 is smaller than the acute angle a 10 .

FIG. 11 is a partial side sectional view of the fuel injection valve according to a third embodiment of the present invention. FIG. 12 is a schematic view similar to FIG. 9 as viewed as indicated by an arrow in FIG. 11 . Referring to FIGS. 11 and 12 , reference character 101 denotes an intake valve, 102 a mushroom-shaped portion of the intake valve 101 , 103 a stem of the intake valve 101 , 104 a valve guide, 105 a fuel injection valve, and 106 a nozzle hole portion of the fuel injection valve 105 . Reference character 107 denotes an intake port, 108 a throttle valve, 109 a cylinder head, 110 a cylinder block, 111 a combustion chamber, P a central portion of the mushroom-shaped portion 102 , and F 100 a fuel spray injected through the nozzle hole portion 106 . In order to make the description easier to understand, the intake valve 101 as illustrated in FIG. 11 is closed. However, when fuel is injected from the fuel injection valve 105 and enters the combustion chamber 111 in the form of fuel spray, the intake valve 101 is actually opened. The fuel injection valve 105 may start injecting fuel at a timing at which the intake valve 101 is actually opened or starts moving toward its open position. However, in consideration of a time period necessary for fuel to reach the intake valve 101 , the fuel injection valve 105 may start injecting fuel even before the intake valve 101 actually starts moving toward its open position. In this case, the aforementioned time period is set such that the fuel injected from the fuel injection valve 105 will reach the intake valve 101 at a timing at which the intake valve 101 actually assumes its open position. Furthermore, if within an allowable range, the fuel injection valve 105 may also start injecting fuel at such a timing that the fuel injected will reach the intake valve 101 even before the intake valve 101 starts moving toward its open position.

As can be seen from FIG. 12 , the fuel injection valve 105 of this embodiment has, as is the case with the first and second embodiments, twelve nozzle holes H 101 to H 112 . The nozzle holes H 105 to H 108 , H 111 and H 112 are located on one side, and the nozzle holes H 101 to H 104 , H 109 and H 110 are located on the other side. Fuel injected through the nozzle holes H 105 to H 108 , H 111 and H 112 enters the combustion chamber via one intake valve (shown in an upper part of FIG. 12 ), whereas fuel injected through the nozzle holes H 101 to H 104 , H 109 and H 110 enters the combustion chamber via the other intake valve (shown in a lower part of FIG. 12 ). Reference characters F 101 to F 112 denote fuel sprays injected from the nozzle holes H 101 to H 112 respectively.

The fuel injection valve 105 is set such that an entire fuel spray F 100 injected through the respective nozzle holes H 101 to H 112 does not reach the central portion P or the stem 103 of the intake valve 101 but only an outer periphery of the mushroom-shaped portion 102 . Since the fuel injected from the fuel injection valve does not adhere to the central portion P or the stem 103 of the intake valve 101 , no delay is caused in supplying fuel to the combustion chamber. Hence, it is possible to improve response in a transient operating state of an internal combustion engine. This effect is significantly increased especially in a case where deposits or the like are attached to a surface of the mushroom-shaped portion 102 .

FIG. 13 is a schematic view similar to FIG. 12 illustrating the fuel injection valve according to a fourth embodiment of the present invention. As can be seen from FIG. 13 , the fuel injection valve 105 of this embodiment has, as is the case with the first through third embodiments, twelve nozzle holes H 201 to H 212 . The nozzle holes H 205 to H 208 , H 211 and H 212 are located on one side, and the nozzle holes H 201 to H 204 , H 209 and H 210 are located on the other side. Fuel injected through the nozzle holes H 205 to H 208 , H 211 and H 212 enters the combustion chamber via one intake valve (shown in an upper part of FIG. 13 ), whereas fuel injected through the nozzle holes H 201 to H 204 , H 209 and H 210 enters the combustion chamber via the other intake valve (shown in a lower part of FIG. 13 ). In order to make the description easier to understand, fuel sprays injected through the nozzle holes 201 to 212 are not illustrated in FIG. 13 .

As is the case with the second embodiment, an entire fuel spray F 200 injected through the respective nozzle holes H 201 to H 212 does not reach the central portion P or the stem 103 of the intake valve 101 but only the outer periphery of the mushroom-shaped portion 102 . Since the fuel injected from the fuel injection valve does not adhere to the central portion P or the stem 103 of the intake valve 101 , no delay is caused in supplying fuel to the combustion chamber. Hence, it is possible to improve response in a transient operating state of an internal combustion engine. This effect is significantly increased especially in the case where deposits or the like are attached to the surface of the mushroom-shaped portion 102 .

In addition, this embodiment is designed such that the fuel spray F 200 certainly reaches the outer periphery portion of the mushroom-shaped portion 102 but does not reach a side thereof where an ignition plug is disposed (shown in a central part of FIG. 13 ). In this case, fuel is less densely distributed on the side of the ignition plug, whereby it is possible to preclude incomplete combustion.

FIG. 14 is a schematic view similar to FIG. 12 illustrating the fuel injection valve according to a fifth embodiment of the present invention. As can be seen from FIG. 14 , the fuel injection valve 105 of this embodiment has, as is the case with the first through fourth embodiments, twelve nozzle holes H 301 to H 312 . The nozzle holes H 305 to H 308 , H 311 and H 312 are located on one side, and the nozzle holes H 301 to H 304 , H 309 and H 310 are located on the other side. Fuel injected through the nozzle holes H 305 to H 308 , H 311 and H 312 enters the combustion chamber via one intake valve (shown in an upper part of FIG. 14 ), whereas fuel injected through the nozzle holes H 301 to H 304 , H 309 and H 310 enters the combustion chamber via the other intake valve (shown in a lower part of FIG. 14 ). In order to make the description easier to understand, fuel sprays injected through the nozzle holes 301 to 312 are not illustrated in FIG. 14 .

As is the case with the third embodiment, an entire fuel spray F 300 injected through the respective nozzle holes H 301 to H 312 does not reach the central portion P or the stem 103 of the intake valve 101 but only the outer periphery of the mushroom-shaped portion 102 . Since the fuel injected from the fuel injection valve does not adhere to the central portion P or the stem 103 of the intake valve 101 , no delay is caused in supplying fuel to the combustion chamber. Hence, it is possible to improve response in a transient operating state of an internal combustion engine. This effect is significantly increased especially in the case where deposits or the like are attached to the surface of the mushroom-shaped portion 102 .

Furthermore, in this embodiment, the nozzle holes H 309 to H 312 have an opening area smaller than that of the nozzle holes H 301 to H 308 so that fuel entering the combustion chamber can be suitably distributed. Thus, fuel sprays (See FIG. 14 ) injected through the nozzle holes H 309 to H 312 exhibit a concentration in low concentration areas 320 lower than that of fuel sprays (See FIG. 14 ) injected through the nozzle holes H 301 to H 308 to high concentration areas 322 . As a result, fuel is less densely distributed on the side of the ignition plug (shown in a central part of FIG. 14 ), whereby it is possible to preclude incomplete combustion.

FIG. 15 is a schematic view similar to FIG. 12 illustrating the fuel injection valve according to a sixth embodiment of the present invention. As can be seen from FIG. 15 , the fuel injection valve 105 of this embodiment has, as is the case with the first through fifth embodiments, twelve nozzle holes H 401 to H 412 . The nozzle holes H 405 to H 408 , H 411 and H 412 are located on one side, and the nozzle holes H 401 to H 404 , H 409 and H 410 are located on the other side. Fuel injected through the nozzle holes H 405 to H 408 , H 411 and H 412 enters the combustion chamber via one intake valve (shown in an upper part of FIG. 15 ), whereas fuel injected through the nozzle holes H 401 to H 404 , H 409 and H 410 enters the combustion chamber via the other intake valve (shown in a lower part of FIG. 15 ). In order to make the description easier to understand, fuel sprays injected through the nozzle holes 401 to 412 are not illustrated in FIG. 15 .

As is the case with the third embodiment, an entire fuel spray F 400 injected through the respective nozzle holes H 401 to H 412 does not reach the central portion P or the stem 103 of the intake valve 101 but only the outer periphery of the mushroom-shaped portion 102 . Since the fuel injected from the fuel injection valve does not adhere to the central portion P or the stem 103 of the intake valve 101 , no delay is caused in supplying fuel to the combustion chamber. Hence, it is possible to improve response in a transient operating state of an internal combustion engine. This effect is significantly increased especially in the case where deposits or the like are attached to the surface of the mushroom-shaped portion 102 .

Furthermore, in this embodiment, the nozzle holes H 409 to H 412 have an opening area larger than that of the nozzle holes H 401 to H 408 so that fuel entering the combustion chamber can suitably be distributed. Thus, fuel sprays (See FIG. 15 ) injected through the nozzle holes H 409 to H 412 exhibit a concentration in high concentration areas 422 higher than that of fuel sprays (See FIG. 15 ) injected through the nozzle holes H 401 to H 408 to low concentration areas 420 . As a result, fuel is more densely distributed on the side of the ignition plug (shown in a central part of FIG. 15 ), whereby it is possible to cause lean fuel to burn.

Although the aforementioned embodiments provide a fuel jet adjusting plate in which twelve nozzle holes are formed, the fuel jet adjusting plate may have any plural number of nozzle holes as long as they are arranged along a plurality of circles that are coaxial with each other.

While the present invention has been described with reference to what are presently considered to be preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments or constructions. On the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various element of the disclosed invention are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.