JP4893709B2 - Fuel injection valve for internal combustion engine - Google Patents

Description

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

  A fuel injection valve for an internal combustion engine, the injection nozzle, an injection hole formed at one end of the injection nozzle, a hemispherical sac chamber communicating with the injection hole, and an upstream side of the sac chamber When the front conical seat portion and the needle valve that is movable in the axial direction of the injection nozzle and abuts against the seat portion, the central axis of the injection hole coincides with the central axis of the sac chamber, the injection hole In general, a fuel injection valve for an internal combustion engine in which fuel spray is injected in a desired direction is generally known.

  In such a fuel injection valve, when the needle valve is moved in the axial direction and the contact with the seat portion is released, the fuel having the substantially same flow velocity along the wall surface of the sac chamber is provided around the nozzle hole inlet. Therefore, there is almost no friction between the fuels due to viscosity in the nozzle hole, and fuel spray can be injected at a relatively high speed from the nozzle hole outlet.

JP 2000-205088 A

  By the way, in the fuel injection valve as described above, the injection hole and the sac chamber are formed in the injection nozzle of the fuel injection valve, and the center axis of each of the injection hole and the sac chamber is machined so as to coincide with each other. It is formed with high accuracy.

  However, there is some manufacturing variation in any machining process, and the nozzle hole and the sac chamber are formed in a state in which the central axes of the nozzle hole and the sac chamber do not coincide with each other and the position is shifted. There is a case. Such misalignment affects the fuel flow rate balance in the nozzle hole, which leads to an unexpected direction of fuel spray injection from the nozzle hole, that is, fuel spray from the nozzle hole. There may be variations in the injection direction.

  As one means for correcting the variation in the injection direction of the fuel spray caused by the misalignment of the central axis between the nozzle hole and the sac chamber, the central axis of the needle valve is eccentric with respect to the central axis of the sac chamber. Thus, it is conceivable to control the flow rate balance around the injection hole of the fuel flowing into the injection hole, thereby equalizing the flow velocity of the fuel in the injection hole and correcting the variation in the injection direction of the fuel spray. Specifically, the fuel injection valve is provided with a mechanism capable of decentering the center axis of the needle valve with respect to the center axis of the sac chamber as disclosed in Patent Document 1, and the injection hole, the sac chamber, The amount of eccentricity of the center axis of the needle valve with respect to the center axis of the sac chamber is determined based on the amount of misalignment of each center axis, and by decentering the needle valve with the amount of eccentricity, the amount of fuel flowing into the nozzle hole is determined. It is conceivable to optimally control the flow rate balance around the nozzle hole, equalize the flow rate of the fuel in the nozzle hole, and inject fuel spray from the nozzle hole in a desired direction.

  However, in the case where the variation in the injection direction of the fuel spray is corrected by decentering the center axis of the needle valve with respect to the center axis of the sac chamber, the center axis of the needle valve is decentered with respect to the center axis of the sac chamber. It is necessary to provide a mechanism capable of controlling the fuel injection valve, which makes the structure of the fuel injection valve very complicated, and is not preferable in terms of manufacturing cost.

  In view of the above-described problems, the present invention provides a structure of a fuel injection valve even when the nozzle hole and the sac chamber are formed in a state in which the central axes of the nozzle hole and the sac chamber do not coincide with each other and are displaced. The flow rate balance around the nozzle hole of the fuel flowing into the nozzle hole can be optimally controlled without complicating the flow rate, and the fuel flow from the nozzle hole can be equalized and the fuel spray from the nozzle hole in the desired direction. It aims at providing the fuel injection valve which can be made to inject.

According to the first aspect of the present invention, there is provided a fuel injection valve for an internal combustion engine, an injection nozzle, an injection hole formed at one end of the injection nozzle, and a hemispherical sac chamber communicating with the injection hole. A pre-conical seat portion continuous upstream of the sac chamber, and a needle valve that is movable in the axial direction of the injection nozzle and abuts against the seat portion, the central axis of the nozzle hole and the In a fuel injection valve for an internal combustion engine in which fuel spray is injected in a desired direction from the nozzle hole when the central axis of the sac chamber is coincident,
The needle valve is a guide portion that slides inside the injection nozzle and guides the needle valve, and includes a guide portion that has at least two fuel passage ports for allowing fuel to flow into the sac chamber, When the center axis and the center axis of the sac chamber are misaligned, each of the at least two fuel passage ports is based on the amount of misalignment between the center axis of the nozzle hole and the center axis of the sac chamber A fuel injection valve for an internal combustion engine is provided in which the fuel passage cross-sectional area is changed so that fuel spray is injected from the injection hole in the desired direction.

  That is, according to the first aspect of the present invention, when the central axis of the injection hole coincides with the central axis of the sac chamber, the fuel spray is injected from the injection hole in a desired direction. When the center axis of the nozzle hole and the center axis of the sac chamber are misaligned, the needle valve is based on the amount of misalignment between the center axis of the nozzle hole and the center axis of the sac chamber. By changing the fuel passage cross-sectional area of the fuel passage opening provided in the guide portion of the fuel, it is possible to optimally control the flow rate balance around the injection hole of the fuel flowing into the injection hole. It is possible to equalize the flow rate of the fuel in the hole and to inject the fuel spray from the nozzle hole in a desired direction. According to the correction of the variation in the injection direction of the fuel spray caused by the misalignment between the central axes of the nozzle hole and the sac chamber, the central axes of the nozzle hole and the sac chamber are not aligned with each other. Even when the nozzle hole and sack chamber are formed in the state of misalignment, the flow rate balance around the nozzle hole of the fuel flowing into the nozzle hole is optimally controlled without complicating the structure of the fuel injection valve It is possible to equalize the flow rate of the fuel in the nozzle hole and to inject the fuel spray from the nozzle hole in a desired direction.

  According to the second aspect of the present invention, when the center axis of the nozzle hole and the center axis of the sac chamber are misaligned, the center axis of the nozzle hole with respect to the center axis of the sack chamber The fuel passage cross-sectional area of the fuel passage port on the position shift direction side of the fuel passage port is the fuel at the fuel passage port on the opposite side to the position shift direction of the center axis line of the nozzle hole with respect to the center axis line of the sac chamber. 2. The fuel injection valve for an internal combustion engine according to claim 1, wherein the fuel injection valve is made larger than a passage cross-sectional area.

  According to the invention described in each claim, an internal combustion engine in which fuel spray is injected in a desired direction from the nozzle hole when the central axis of the nozzle hole coincides with the central axis of the sac chamber. Even if the injection hole and the sac chamber are formed in a state where the central axes of the injection hole and the sac chamber do not coincide with each other and the position is shifted, the structure of the fuel injection valve is complicated. Therefore, it is possible to optimally control the flow rate balance around the nozzle hole of the fuel flowing into the nozzle hole, equalizing the flow velocity of the fuel in the nozzle hole and directing the fuel spray from the nozzle hole in a desired direction. There is a common effect that enables injection.

  The fuel injection valve of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of an embodiment of a fuel injection valve of the present invention. In FIG. 1, 1 is an injection nozzle, 2 is an injection hole formed at one end of the injection nozzle 1, 3 is a hemispherical sac chamber communicating with the injection hole 2, and 4 is a prefix continuous upstream of the sac chamber 3. A conical seat portion 5 is movable in the axial direction of the injection nozzle 1 and is in contact with the seat portion 4, 6 is a fuel supply passage, 7 is a needle valve 5 with respect to the injection nozzle 1 around its central axis. A rotating shaft 8 for rotating the rotating shaft 7 and a rotating mechanism 8 for rotating the rotating shaft 7 respectively. The needle valve 5 is a guide portion that slides in the injection nozzle 1 and guides the needle valve 5, and has a guide portion 9 that has at least two fuel passage ports for allowing fuel to flow into the sac chamber 3.

  In the fuel injection valve in the present embodiment, when the central axis of the injection hole 2 and the central axis of the sac chamber 3 coincide with each other, the fuel spray is directed from the injection hole 2 to a desired injection direction, that is, the central axis of the injection hole 2. The fuel spray is injected in the matching direction. Then, when the needle valve 5 is moved in the axial direction and the contact with the seat portion 4 is released, the fuel having substantially the same flow velocity flows along the wall surface of the sac chamber 3 around the nozzle hole inlet. In addition, there is almost no friction between the fuels due to viscosity in the nozzle hole, and the fuel spray can be injected at a relatively high speed from the nozzle hole outlet.

  By the way, in the fuel injection valve as described above, the injection hole 2 and the sac chamber 3 are formed in the injection nozzle 1 of the fuel injection valve, and the central axes of the injection hole 2 and the sac chamber 3 coincide with each other. Thus, it is formed with high precision by machining.

  However, there is some manufacturing variation in any machining process, and the nozzle hole 2 and the sac chamber 3 are in a state where the central axes of the nozzle hole 2 and the sac chamber 3 do not coincide with each other and are displaced. And may be formed. Such misalignment affects the flow velocity balance of the fuel in the nozzle hole 2, which leads to an unexpected direction of the fuel spray from the nozzle hole 2, that is, from the nozzle hole 2. There may be variations in the injection direction of the fuel spray.

  FIG. 2 is a schematic diagram showing a state in which the central axis of the nozzle hole 2 coincides with the central axis of the sac chamber 3 and fuel spray is injected from the nozzle hole 2 in a desired injection direction. FIG. 3 is a schematic diagram showing a state in which the central axis of the nozzle hole 2 and the central axis of the sac chamber 3 are misaligned and fuel spray is not injected from the nozzle hole 2 in a desired injection direction.

  As shown in FIG. 2, when the central axis of the nozzle hole 2 and the central axis of the sac chamber 3 coincide with each other, the sac chamber 3 from the seat portion 4 to the nozzle hole 2 along the wall surface of the sack chamber 3. The two distances a1 and a2 in the height direction are equal. As a result, fuel of almost the same flow velocity flows along the wall surface of the sac chamber 3 around the entrance of the nozzle hole 2 that opens to the sac chamber 3, so that friction between the fuels due to viscosity occurs in the nozzle hole 2. Almost no fuel spray is injected at a relatively high speed from the nozzle hole outlet, and the fuel spray is injected in a desired fuel spray injection direction, that is, a direction that coincides with the central axis of the nozzle hole.

  However, as shown in FIG. 3, when the center axis of the nozzle hole 2 and the center axis of the sac chamber 3 are misaligned, from the seat portion 4 to the nozzle hole 2 along the wall surface of the sack chamber 3. The two distances b1 and b2 in the height direction of the sac chamber 3 are different. Thereby, the flow velocity balance of the fuel in the nozzle hole is broken, and a large energy loss due to friction between these fuels occurs in the nozzle hole 2, the fuel injection speed is lowered, and the fuel spray is a desired fuel spray. Injection direction, that is, a direction different from the direction corresponding to the central axis of the nozzle hole 2, that is, the fuel spray injection direction varies.

  Based on this, in the fuel injection valve of the internal combustion engine of the present invention, when the center axis of the nozzle hole 2 and the center axis of the sac chamber 3 are misaligned, the center axis of the nozzle hole 2 An injection hole for fuel flowing into the injection hole 2 by changing the fuel passage cross-sectional area of the fuel passage opening provided in the guide portion 9 of the needle valve 5 based on the amount of positional deviation from the center axis of the sac chamber 3 Optimum control of the surrounding flow rate balance and equalization of the fuel flow velocity in the nozzle hole, and correction of variations in the fuel spray injection direction caused by the misalignment of the central axes of the nozzle hole 2 and the sac chamber 3 Thus, the fuel spray from the nozzle hole 2 can be injected in a desired direction.

  More specifically, when the center axis of the nozzle hole 2 and the center axis of the sac chamber 3 are misaligned, the position of the center axis of the nozzle hole 2 in the position misalignment direction side with respect to the center axis of the sack chamber 3 The fuel passage cross-sectional area of the fuel passage port in the fuel passage port is made larger than the fuel passage cross-sectional area of the fuel passage port on the opposite side of the center axis of the nozzle hole 2 with respect to the direction of displacement of the center axis of the injection hole As a result, the flow rate balance around the injection hole of the fuel flowing into the injection hole 2 is optimally controlled, the flow velocity of the fuel in the injection hole is equalized, and the center axis lines of the injection hole 2 and the sack chamber 3 are displaced. The variation in the injection direction of the resulting fuel spray is corrected.

  FIG. 4 is a view showing an embodiment of the fuel passage port of the guide portion 9 that is applied when the center axis of the injection hole 2 and the center axis of the sac chamber 3 coincide with each other. FIG. 5 is a view showing an embodiment of the fuel passage port of the guide portion 9 applied when the center axis of the nozzle hole 2 and the center axis of the sac chamber 3 are misaligned.

  As shown in FIG. 4, in the guide portion 9 of the needle valve 5 in the present embodiment, four fuel passage ports 10 a, 10 b, 10 c, and 10 d are symmetrical with respect to the central axis of the needle valve 5 and in the circumferential direction. When the central axis of the nozzle hole 2 and the central axis of the sac chamber 3 coincide with each other, the fuel passage cross-sectional areas of the four fuel passage openings are the same. As a result, since fuel of almost the same flow velocity flows along the wall surface of the sac chamber 3 around the entrance of the nozzle hole 2 that opens to the sac chamber 3, friction between the fuels due to viscosity occurs in the nozzle hole 2. Almost no fuel spray is injected at a relatively high speed from the nozzle hole outlet, and the fuel spray is injected in a desired fuel spray direction, that is, in a direction corresponding to the central axis of the nozzle hole 2.

  On the other hand, when the center axis line of the nozzle hole 2 and the center axis line of the sac chamber 3 are misaligned, the center axis line of the nozzle hole 2 is determined with reference to the center axis line of the sack chamber 3 as shown in FIG. The two fuel passage cross-sectional areas of the two fuel passage ports 10a and 10b on the side of the positional deviation direction are set to the two fuels on the opposite side to the positional deviation direction of the central axis of the nozzle hole 2 with respect to the central axis of the sack chamber 3. By making it larger than the fuel passage cross-sectional area of the passage openings 10c and 10d, the flow rate balance around the injection hole of the fuel flowing into the injection hole 2 can be optimally controlled, and the flow rate of the fuel in the injection hole can be equalized. It is possible to inject the fuel spray in the injection direction of the fuel spray, that is, in the direction coinciding with the central axis of the nozzle hole 2.

  Further, as described above, the fuel passage cross-sectional area of the fuel passage port of the guide portion 9 is changed based on the amount of displacement between the central axis of the nozzle hole 2 and the central axis of the sac chamber 3. The fuel passage cross-sectional area of each fuel passage opening of the guide portion 9 is a map in which the fuel passage cross-sectional area can be calculated from the amount of misalignment between the central axis of the nozzle hole 2 and the central axis of the sac chamber 3. It is calculated based on a map prepared in advance based on an evaluation test or the like.

  In addition, the quantity and shape of the fuel passage port disposed in the guide portion 9 of the needle valve 5 are not limited to the fuel passage port as shown in FIGS. Even in the case where the axis and the center axis of the sac chamber 3 are misaligned, the number and shape may be any as long as the flow velocity of the fuel in the nozzle hole can be equalized.

  Below, the outline of the manufacture assembly process of the injection nozzle 1 and the needle valve 5 of the fuel injection valve of this embodiment is demonstrated. FIG. 6 is a flowchart showing an embodiment of a manufacturing and assembling process of the injection nozzle 1 and the needle valve 5 of the fuel injection valve.

  In the flowchart shown in FIG. 6, first, in step 101, the amount of positional deviation between the central axis of the injection hole 2 and the central axis of the sac chamber 3 in the injection nozzle 1 manufactured by machining is inspected. In the present embodiment, the displacement amount of the central axis of the nozzle hole 2 with respect to the central axis of the sac chamber 3 is inspected.

  In step 102 subsequent to step 101, the fuel passage cross-sectional area of each fuel passage port of the guide portion 9 suitable for equalizing the flow velocity of the fuel in the nozzle hole is determined so that the center axis of the nozzle hole 2 and the sac chamber 3 Calculated based on the amount of positional deviation from the central axis. Specifically, even when the center axis of the nozzle hole 2 and the center axis of the sac chamber 3 are misaligned, the sac chamber is configured so that the flow velocity of the fuel in the nozzle hole can be equalized. 3, the fuel passage cross-sectional area of the fuel passage opening on the side of the displacement direction of the central axis of the nozzle hole 2 with respect to the central axis of the nozzle hole 2 is in the direction of the positional deviation of the central axis of the nozzle hole 2 with respect to the central axis of the sack chamber 3. On the other hand, it is set larger than the fuel passage cross-sectional area of the fuel passage port on the opposite side. In the present embodiment, the fuel passage cross-sectional area of each fuel passage of the guide portion 9 can be calculated from the amount of misalignment between the central axis of the nozzle hole 2 and the central axis of the sac chamber 3. It is assumed that the map is calculated using a map prepared in advance based on an evaluation test or the like.

  In step 103 subsequent to step 102, each fuel passage port having an appropriate fuel passage cross-sectional area calculated in step 102 is formed in the guide portion 9 of the needle valve 5 by machining or the like.

  In step 104 following step 103, the needle valve 5 in which each fuel passage port is formed in the guide portion 9 is assembled to the injection nozzle 1. At this time, in order to equalize the flow velocity of the fuel in the nozzle hole, each fuel passage port of the guide portion 9 having the fuel passage cross-sectional area calculated in step 102 is injected with reference to the central axis of the sack chamber 3. The needle valve 5 is assembled to the injection nozzle 1 by using a rotation mechanism portion 8 that can rotate the needle valve 5 so that the needle valve 5 can be appropriately arranged with respect to the displacement direction of the central axis of the hole 2. That is, the fuel passage cross-sectional area of the fuel passage port of the guide portion 9 on the side of the displacement direction of the center axis of the nozzle hole 2 with respect to the center axis of the sac chamber 3 is the nozzle hole 2 with respect to the center axis of the sack chamber 3. The needle valve 5 is assembled to the injection nozzle 1 so as to be larger than the fuel passage cross-sectional area of the fuel passage port of the guide portion 9 on the opposite side to the direction of displacement of the center axis of the guide shaft 9.

  According to the fuel injection valve manufactured by such a manufacturing and assembling process, even when the center axis of the nozzle hole 2 and the center axis of the sac chamber 3 are misaligned, the structure of the fuel injection valve is complicated. Therefore, the flow rate balance around the injection hole of the fuel flowing into the injection hole 2 can be optimally controlled, and the flow rate of the fuel in the injection hole 2 is equalized so that the fuel spray from the injection hole 2 is directed in a desired direction. It becomes possible to inject.

1 is a schematic cross-sectional view of an embodiment of a fuel injection valve of the present invention. It is a schematic diagram showing a state in which the central axis of the injection hole coincides with the central axis of the sac chamber and fuel spray is injected from the injection hole in a desired injection direction. It is a schematic diagram showing a state where the central axis of the injection hole and the central axis of the sac chamber are misaligned and fuel spray is not injected from the injection hole in a desired injection direction. It is a figure which shows one Embodiment of the fuel passage opening of the guide part applied when the center axis line of a nozzle hole corresponds with the center axis line of a sac chamber. It is a figure which shows one Embodiment of the fuel passage port of the guide part applied when the center axis line of a nozzle hole and the center axis line of a sac chamber have shifted. It is a flowchart which shows one Embodiment of the manufacture assembly process of the injection nozzle and needle valve of this fuel injection valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection nozzle 2 Injection hole 3 Suck chamber 4 Seat part 5 Needle valve 9 Guide part 10a Fuel passage port 10b Fuel passage port 10c Fuel passage port 10d Fuel passage port

Claims (2)

A fuel injection valve for an internal combustion engine, the injection nozzle, an injection hole formed at one end of the injection nozzle, a hemispherical sac chamber communicating with the injection hole, and an upstream side of the sac chamber It has a prefix cone-shaped seat portion and a needle valve that is movable in the axial direction of the injection nozzle and abuts against the seat portion, and the central axis of the nozzle hole coincides with the central axis of the suck chamber In the fuel injection valve of the internal combustion engine, in which the fuel spray is injected in a desired direction from the nozzle hole,
The needle valve is a guide portion that slides in the injection nozzle and guides the needle valve, and includes a guide portion that has at least two fuel passage ports that allow fuel to flow into the sac chamber,
When the center axis of the nozzle hole and the center axis of the sac chamber are misaligned, the at least two fuels are based on the amount of misalignment between the center axis of the nozzle hole and the center axis of the sack chamber. A fuel injection valve for an internal combustion engine, wherein each fuel passage cross-sectional area of the passage opening is changed so that fuel spray is injected from the nozzle hole in the desired direction.   When the center axis of the nozzle hole and the center axis of the sac chamber are misaligned, the fuel passage port located on the side of the misalignment direction of the center axis of the nozzle hole with respect to the center axis of the sack chamber The fuel passage cross-sectional area of the fuel passage is made larger than the fuel passage cross-sectional area of the fuel passage port on the opposite side to the positional deviation direction of the central axis of the nozzle hole with respect to the central axis of the sac chamber. The fuel injection valve for an internal combustion engine according to claim 1, wherein the fuel injection valve is an internal combustion engine.

Images