JP2006029131A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve in which atomization of fuel injected from an injection hole is promoted, without increasing the size of the fuel injection valve. <P>SOLUTION: The fuel passes through a slit-like second hole part 42, so that the fuel is in a flat liquid column and the fuel flows into a first hole part 41. A part on a first hole part 41 side of the second hole part 42 is connected with a position not including a center shaft of the first hole part 41, and is connected in the tangential direction of a side face part 44 of the first hole part 41 in the end part on the first hole part 41 side. The fuel flowing from the second hole part 42 into the first hole part 41 is guided by the side face part 44 of the first hole part 41 and is swirled. Therefore, a swirl flow of the fuel is injected from the injection hole 40. Since the first hole part 41 is connected with the second hole part 42 in an injection hole plate 30 at an angle α, occupation area of the second hole part 41 in a radial direction of the first hole part 41 is reduced. Therefore, atomization of the fuel injected from the injection hole 40 is promoted without increasing the size of the fuel injection valve. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve for an internal combustion engine (hereinafter, the internal combustion engine is referred to as an “engine”).

  2. Description of the Related Art Conventionally, a fuel injection valve that promotes atomization of fuel is known that includes a nozzle hole forming member that forms a nozzle hole at the tip of a valve body. By forming the nozzle hole in the nozzle hole forming member, the fuel that has passed through the fuel passage formed between the valve member and the valve body is distributed to each nozzle hole of the nozzle hole forming member, thereby promoting atomization. It is done. In order to promote atomization of fuel, it is conceivable to apply a turning force to the fuel flowing through the nozzle hole. By applying a swirling force to the fuel flowing through the nozzle hole, a liquid film fuel that forms a swirling flow is injected from the nozzle hole. As a result, separation of the fuel liquid film is promoted, and fuel atomization is achieved. As a technique for imparting a turning force to the fuel flowing through the nozzle hole, for example, a fuel injection valve disclosed in Patent Document 1 is known.

JP 2002-36496 A

  The fuel injection valve disclosed in Patent Document 1 has a guide groove that guides the flow of fuel to the injection hole on the fuel inlet side of the injection hole. The guide groove is disposed so as to be shifted from the central axis of the nozzle hole, and is extended from the wall surface forming the nozzle hole in a tangential direction. As a result, the fuel guided into the guide groove and flowing into the nozzle hole swirls along the wall surface forming the nozzle hole to form a swirling flow.

  However, in the case of the fuel injection valve disclosed in Patent Document 1, a flow path for guiding the flow of fuel to the injection hole is required on the inlet side of the injection hole. This flow path is formed to extend radially outward from the nozzle hole. Therefore, the occupied area of the flow path needs several times to several tens of times compared with the cross-sectional area of the nozzle hole. As a result, in order to promote atomization by the formation of the swirl flow, there is a problem that the injection hole forming member, and thus the fuel injection valve, is increased in size.

  Accordingly, an object of the present invention is to provide a fuel injection valve that promotes atomization of fuel injected from a nozzle hole without causing an increase in size of the physique.

  In the first aspect of the present invention, the nozzle hole has a first hole and a second hole. The first hole has an open end and a closed end. The slit-shaped second hole portion is connected to the closed end portion side of the first hole portion at an angle α. The fuel that has passed through the fuel passage formed between the valve body and the valve member flows into the first hole through the slit-shaped second hole. The fuel flows into the first hole by passing through the slit-shaped second hole to form a flat liquid column. The flat liquid columnar fuel that has flowed into the first hole is guided to the wall surface of the nozzle hole forming member that forms the first hole having a predetermined angle with respect to the flow direction along the central axis of the second hole. Is done. Therefore, the fuel that has flowed into the first hole turns along the wall surface of the nozzle hole forming member that forms the first hole. Thereby, the fuel which formed the swirl | vortex flow is injected from a nozzle hole. Further, since the first hole portion and the second hole portion are connected to form an angle α inside the nozzle hole forming member, the area occupied by the nozzle hole in the cross section perpendicular to the central axis of the nozzle hole forming member is Reduced. Therefore, atomization of the fuel injected from the nozzle hole can be promoted without increasing the size of the physique. Further, the angle α formed by the central axis of the first hole and the central axis of the second hole is set to 20 ° ≦ α <80 °. When α is small, the first hole and the second hole are arranged substantially linearly, and the fuel flowing from the second hole to the first hole is less likely to turn. On the other hand, when α increases, the fuel that has passed through the second hole portion easily collides with the closed end portion of the first hole portion. Therefore, it becomes difficult for the fuel to turn in the first hole. Therefore, α is set in the range of 20 ° to 80 °.

  In the second aspect of the present invention, the end of the second hole on the first hole side is open in at least one of the closed end and the side surface of the first hole. Therefore, the fuel that has passed through the second hole collides with the wall surface of the nozzle hole forming member that forms the first hole at an angle α. Further, the area occupied by the nozzle holes in the cross section perpendicular to the central axis of the nozzle hole forming member is reduced. Therefore, atomization of the fuel injected from the nozzle holes can be promoted without increasing the size of the physique.

In the invention according to claim 3, the total length of the arc of the second hole opening to the first hole is ¼ or less of the total length of the side surface of the first hole. Therefore, the fuel that passes through the second hole flows into the first hole as a thin liquid column. As a result, the fuel forms a swirling flow along the side surface of the first hole. As a result, the fuel to which the turning force is applied in the first hole is injected from the injection hole. Therefore, atomization of fuel can be promoted.
In the invention according to claim 4, the central axis of the first hole is not included in the projection region obtained by extending the end of the second hole on the first hole side. Therefore, the fuel flowing into the first hole from the second hole forms a swirling flow along the side surface of the first hole. Therefore, the fuel forms a swirling flow and can promote atomization of the fuel injected from the injection hole.

In the invention according to claim 5, the second imaginary straight line extending from the wall surface on the side farther from the first imaginary straight line in the second hole portion than the third imaginary straight line extending from the wall surface of the nozzle hole forming member forming the first hole portion. Located on the first virtual straight line side. That is, the second imaginary straight line and the third imaginary straight line are arranged to deviate from each other, and the second hole portion is connected to the inner side of the side surface portion of the first hole portion.
In the invention described in claim 6, when the radius of the first hole is R1, the distance d1 between the second virtual line and the third virtual line defined in claim 5 is set as d1 ≦ R1 × 0.2. Has been. The smaller the d1 is, the closer the second virtual line and the third virtual line are. That is, as d1 becomes smaller, the wall surface on the side farther from the first virtual line of the second hole portion approaches the tangent of the side surface portion of the first hole portion. When d1 = 0, the wall surface on the side farther from the first virtual line of the second hole portion and the tangent of the side surface portion forming the first hole portion coincide with each other. On the other hand, when d1 becomes large, the wall surface on the side farther from the first virtual line of the second hole portion approaches the central axis of the first hole portion. Therefore, the fuel that has flowed into the first hole portion from the second hole portion becomes difficult to flow along the side surface portion of the first hole portion, and it becomes difficult to form a swirling flow. Therefore, d1 is set to 0.2 times or less of the radius R1 of the first hole.

  In the invention according to claim 7, the second imaginary straight line extending from the wall surface on the side farther from the first imaginary straight line in the second hole portion than the third imaginary straight line extending from the side surface portion of the nozzle hole forming member forming the first hole portion. Is also located on the opposite side of the first virtual straight line. In other words, the second imaginary straight line and the third imaginary straight line are arranged so as to deviate from each other, and the second hole portion is connected to the outside of the side surface portion of the nozzle hole forming member that forms the first hole portion.

  In the eighth aspect of the invention, when the radius of the first hole is R1, the distance d2 between the second virtual line and the third virtual line defined in claim 7 is set as d2 ≦ R1 × 0.4. Has been. The smaller the d2 is, the closer the second virtual line and the third virtual line are. That is, as d2 becomes smaller, the wall surface on the side farther from the first virtual line of the second hole portion approaches the tangent of the side surface portion forming the first hole portion. When d2 = 0, the wall surface on the side farther from the first virtual line of the second hole portion and the tangent of the side surface portion forming the first hole portion coincide with each other. On the other hand, when d2 becomes large, the wall surface on the side farther from the first imaginary straight line of the second hole portion moves away from the central axis of the first hole portion. Therefore, a step is formed between the second hole and the side surface of the first hole. As a result, the fuel flowing into the first hole from the second hole is prevented from flowing by the step. This makes it difficult for the fuel to flow along the side surface portion of the first hole portion, making it difficult to form a swirling flow. Therefore, d2 is set to 0.4 times or less of the radius R1 of the first hole.

  In the invention of claim 9, the length H of the opening of the second hole portion in the central axis direction of the first hole portion is between the full length B of the side surface portion at the end portion on the opening side of the first hole portion, B × 0.5 <H × tan α <B × 1.3. As H becomes smaller, the liquid film of fuel tends to be partially biased at the outlet of the nozzle hole. Therefore, the lower limit of H × tan α is set to 0.5 times B. Moreover, when H becomes large, the end portions of the liquid film formed inside the nozzle hole are likely to come into contact with each other, and fuel atomization is hindered. Therefore, the upper limit of H × tan α is set to 1.3 times B.

  In the invention according to claim 10, the first hole portion opens in the flat portion of the nozzle hole forming member. The plane portion and the first hole portion form an angle of 60 ° to 90 °. For example, when the nozzle hole forming member is formed in a plate shape, the surface on the valve body side that is the fuel inlet side of the nozzle hole and the surface on the fuel outlet side opposite to the valve body are substantially parallel. When the first hole is inclined with respect to the central axis of the valve body, the opening side of the first hole is inclined with respect to the surface of the injection hole forming member opposite to the valve body. Therefore, the length of the side surface portion of the first hole portion in the central axis direction of the first hole portion is different in the circumferential direction. As a result, part of the fuel is injected during the turning in the first hole, and the directionality of the fuel spray is reduced. By forming the flat surface portion in the nozzle hole forming member, the difference in the overall length of the first hole portion in the circumferential direction is reduced. Therefore, the directionality of fuel spray can be improved.

  In the invention described in claim 11, the nozzle hole forming member has a tapered portion on the opening side of the first hole portion. In the taper portion, the inner diameter gradually increases. Therefore, although the velocity component of the fuel does not change in the axial direction, the circumferential velocity component decreases as the inner diameter of the tapered portion increases because the angular velocity is preserved. As a result, the velocity component in the axial direction becomes relatively large on the outlet side of the tapered portion. This makes it difficult for the fuel to expand in the circumferential direction at the outlet of the nozzle hole, and the spray angle becomes small. Therefore, collision between sprays can be reduced.

In the invention described in claim 12, the tapered portion opens in the flat portion of the nozzle hole forming member. The flat portion and the tapered portion form an angle of 60 ° to 90 °. By forming the flat surface portion on the nozzle hole forming member, the difference in the overall length of the tapered portion in the circumferential direction is reduced. Therefore, the directionality of fuel spray can be improved.
In the invention according to claim 13, the angle β formed by the long axis of the second hole portion and the tangent line of the circumference where the plurality of injection holes are arranged is 0 ° ≦ β ≦ 45 °. The fuel that has passed through the fuel passage uniformly flows from the outer peripheral side to the central axis side of the injection hole forming member along the inner wall of the valve body. By setting 0 ° ≦ β ≦ 45 °, the fuel flows substantially perpendicular to the long axis of the second hole. As a result, the fuel that has passed through the second hole forms a uniform swirl flow inside the first hole. Therefore, uniform spray can be formed in the plurality of nozzle holes.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 2 shows a fuel injection valve (hereinafter referred to as “injector”) according to the first embodiment of the present invention. The injector 10 according to the first embodiment is installed in an intake port (not shown) through which fuel sucked into a combustion chamber of a gasoline engine flows. The injector 10 injects fuel into the intake air flowing through the intake port. The injector 10 may be applied to a direct injection engine. When the injector 10 is applied to a direct injection engine, the injector 10 is mounted on a cylinder head of the engine. The injector 10 may be applied to a diesel engine.

  The housing 11 of the injector 10 is formed in a cylindrical shape. The housing 11 has a first magnetic part 12, a nonmagnetic part 13, and a second magnetic part 14. The nonmagnetic part 13 prevents a magnetic short circuit between the first magnetic part 12 and the second magnetic part 14. The first magnetic part 12, the nonmagnetic part 13, and the second magnetic part 14 are integrally connected by, for example, laser welding. In addition, the housing 11 may be formed into a cylindrical integral with a magnetic member, and the portion corresponding to the nonmagnetic portion 13 may be made nonmagnetic by heat processing.

  An inlet member 15 is installed at one end of the housing 11 in the axial direction. The inlet member 15 is press-fitted on the inner peripheral side of the housing 11. The inlet member 15 has a fuel inlet 16. Fuel is supplied to the fuel inlet 16 from a fuel pump (not shown). The fuel supplied to the fuel inlet 16 flows into the inner peripheral side of the housing 11 via the fuel filter 17. The fuel filter 17 removes foreign matters contained in the fuel.

  A nozzle holder 20 is installed at the other end of the housing 11. The nozzle holder 20 is formed in a cylindrical shape, and a valve body 21 is installed inside. The valve body 21 is formed in a cylindrical shape, and an end opposite to the fuel inlet 16 in the axial direction is open. The valve body 21 is fixed to the nozzle holder 20 by, for example, press fitting or welding. As shown in FIG. 3, the valve body 21 has a valve seat 23 on a conical inner wall 22 whose inner diameter decreases as it approaches the tip. A nozzle hole plate 30 as a nozzle hole forming member is installed at the end of the valve body 21 opposite to the housing 11. The nozzle hole plate 30 is formed in a cup shape that covers the tip of the valve body 21. The nozzle hole plate 30 forms a plurality of nozzle holes 40.

  As shown in FIG. 2, the needle 24 as a valve member is accommodated on the inner peripheral side of the housing 11, the nozzle holder 20 and the valve body 21 so as to be capable of reciprocating in the axial direction. The needle 24 is disposed substantially coaxially with the valve body 21. The needle 24 has a seal portion 25 on one end side in the axial direction, that is, on the side opposite to the fuel inlet 16. The seal portion 25 can contact a valve seat 23 formed on the valve body 21. The needle 24 forms a fuel passage 26 through which fuel flows between the needle body 24 and the valve body 21.

  The injector 10 has a drive unit 60 that drives the needle 24. The drive unit 60 includes a spool 61, a coil 62, a fixed core 63, a plate housing 64, and a movable core 65. The spool 61 is installed on the outer peripheral side of the housing 11. The spool 61 is formed of a resin in a cylindrical shape, and a coil 62 is wound on the outer peripheral side. The coil 62 is connected to the terminal portion 67 of the connector 66. The fixed core 63 is installed on the inner peripheral side of the coil 62 with the housing 11 in between. The fixed core 63 is formed in a cylindrical shape from a magnetic material such as iron. The fixed core 63 is fixed to the inner peripheral side of the housing 11 by, for example, press fitting. A plate housing 64 that is a magnetic member covers the outer peripheral side of the coil 62. The outer peripheral sides of the spool 61 and the coil 62 are covered with a resin mold 68 that integrally forms a connector 66.

  The movable core 65 is installed on the inner peripheral side of the housing 11 so as to be capable of reciprocating in the axial direction. The movable core 65 is formed in a cylindrical shape from a magnetic material such as iron. The movable core 65 is integrally connected to the needle 24 at the end opposite to the fixed core 63. The movable core 65 is in contact with the spring 18 that is a biasing means at the end on the fixed core 63 side. One end of the spring 18 is in contact with the movable core 65, and the other end is in contact with the adjusting pipe 19 that is press-fitted into the fixed core 63. The spring 18 has a force extending in the axial direction. Therefore, the integral movable core 65 and the needle 24 are pressed by the spring 18 in the direction of seating on the valve seat 23. By adjusting the press-fitting amount of the adjusting pipe 19 press-fitted into the fixed core 63, the load of the spring 18 is adjusted. When the coil 62 is not energized, the movable core 65 and the needle 24 are pressed toward the valve seat 23, and the seal portion 25 is seated on the valve seat 23.

Next, the nozzle hole 40 of the nozzle hole plate 30 will be described in detail.
As shown in FIG. 3, the nozzle hole plate 30 is attached to the distal end side of the valve body 21, that is, the side opposite to the housing 11. In FIG. 3, the description of the nozzle holder 20 is omitted. The nozzle hole plate 30 is formed in a cup shape having a cylindrical portion 31 and a bottom portion 32. As for the nozzle hole plate 30, the cylindrical portion 31 is sandwiched between the outer peripheral wall of the valve body 21 and the inner peripheral wall of the nozzle holder 20, and the bottom portion 32 is between the outer bottom surface of the valve body 21 and the inner bottom surface of the nozzle holder 20. It is sandwiched between.

  The nozzle hole plate 30 has a plurality of nozzle holes 40 as shown in FIG. In the case of this embodiment, the nozzle hole plate 30 has five nozzle holes 40 at equal intervals in the circumferential direction. The five nozzle holes 40 are arranged on a circumference C centering on the central axis of the nozzle hole plate 30. The nozzle hole 40 formed by the nozzle hole plate 30 is composed of a first hole part 41 and a second hole part 42 as shown in FIGS. 1, 4 and 5. The bottom 32 of the nozzle hole plate 30 has an inlet side end face 30 a on the outer bottom side of the valve body 21 and an outlet side end face 30 b on the inner bottom side of the nozzle holder 20. The first hole 41 is formed in the bottom 32 of the nozzle hole plate 30 from the outlet side end face 30b to the inlet side end face 30a up to the middle of the thickness of the nozzle hole plate 30. Thereby, as for the 1st hole part 41, one edge part is opened to the exit side end surface 30b in the axial direction, and the other edge part is obstruct | occluded. The closed end of the first hole 41 is a closed end 43. The first hole portion 41 is formed in a cylindrical shape having substantially the same inner diameter in the axial direction. Thereby, the side part 44 of the nozzle hole plate 30 which forms the 1st hole part 41 becomes cylindrical surface shape. The first hole portion 41 is inclined with respect to the thickness direction of the nozzle hole plate 30.

  The second hole 42 is formed from the inlet side end face 30 a to the first hole 41 at the bottom 32 of the nozzle hole plate 30. Thereby, as for the 2nd hole part 42, one edge part is opened to the entrance side end surface 30a, and the other edge part is opening to the 1st hole part 41 in the axial direction. Similar to the first hole 41, the second hole 42 is inclined with respect to the central axis of the valve body 21. The end portion of the second hole portion 42 on the first hole portion 41 side opens to the closed end portion 43 and the side surface portion 44 of the first hole portion 41. Note that the end portion of the second hole portion 42 on the first hole portion 41 side may open only to the closed end portion 43 or only the side surface portion 44 of the first hole portion 41. The second hole 42 has a flat slit shape in which the shape of the cross section perpendicular to the central axis P2 and the shape of the opening in the inlet side end face 30a have a major axis and a minor axis. In the case of this embodiment, the cross section of the second hole portion 42 is a flat rectangular shape, that is, a rectangle.

  When the seal portion 25 of the needle 24 is separated from the valve seat 23 of the valve body 21, the fuel in the fuel passage 26 flows into the inlet side of the injection hole 40 through the gap between the needle 24 and the valve body 21. At this time, the fuel uniformly flows from the radially outer side of the nozzle hole plate 30 shown in FIG. 4 toward the center along the conical inner wall 22 of the valve body 21. The long-axis extension line Pf of the second hole portion 42 is substantially parallel to the tangent t of the circumference C where the plurality of injection holes 40 of the injection hole plate 30 are arranged as shown in FIG. That is, if the angle formed by the long axis extension line Pf of the second hole portion 42 and the tangent t of the circumference C is β, β = 0 °. Therefore, the second hole portion 42 of the nozzle hole 40 is substantially perpendicular to the fuel flow from the radially outer side of the nozzle hole plate 30 toward the center. As a result, the fuel flows uniformly into the second hole portions 42 of the plurality of nozzle holes 40. The fuel that has flowed into the second hole 42 is injected through the first hole 41.

  Note that an angle β formed by the long-axis extension line Pf of the plurality of nozzle holes 40 of the nozzle hole plate 30 and the tangent t of the circumference C where the nozzle holes 40 are arranged is as shown in FIG. To about 45 °. That is, the angle β may be 0 ° ≦ β ≦ 45 °. When β is greater than 45 °, the angle of the second hole portion 42 of the nozzle hole 40 with respect to the fuel flow increases, and the velocity distribution is likely to occur in the fuel flowing into the second hole portion 42. When the velocity distribution is generated in the fuel flowing into the second hole portion 42, the fuel flow in the second hole portion 42 is disturbed. Therefore, the fuel that has flowed into the first hole 41 from the second hole 42 varies in the turning force of each nozzle hole. As a result, it becomes difficult to form a uniform spray at each nozzle hole 40 of the nozzle hole plate 30. Therefore, the upper limit of β is set to 45 °.

In this embodiment, the 1st hole part 41 and the 2nd hole part 42 satisfy | fill the following conditions, and are connected.
The central axis P1 of the first hole 41 and the central axis P2 of the second hole 42 form an angle α as shown in FIG. 1, and the angle α is set to 20 ° ≦ α <80 °. Yes. When α increases, the fuel that has passed through the second hole portion 42 is more likely to collide with the closed end portion 43 than the side surface portion 44 of the first hole portion 41. Therefore, the fuel that has passed through the second hole 42 is less likely to form a flow along the side surface 44 of the first hole 41. As a result, the turning force applied to the fuel passing through the first hole 41 is reduced. Further, when α increases, the overall length of the second hole portion 42 in the radial direction of the first hole portion 41 increases. Therefore, when α increases, the occupation area of the second hole portion 42 increases. Therefore, the upper limit of α is set to 80 °.

  On the other hand, when α decreases, the first hole 41 and the second hole 42 are positioned on substantially the same straight line. Therefore, the fuel that has passed through the second hole 42 flows through the first hole 41 without colliding with the side surface 44 of the first hole 41, and forms a flow along the side surface 44 of the first hole 41. It becomes difficult to do. As a result, the turning force applied to the fuel passing through the first hole 41 is reduced. Therefore, the lower limit of α is set to 20 °.

  As shown in FIG. 7, the second hole portion 42 is connected to the side surface portion 44 of the first hole portion 41 in a cross section perpendicular to the central axis P <b> 1 of the first hole portion 41. At this time, the length of the arc in the circumferential direction of the first hole portion 41 is A in the second hole portion 42 that opens to the side surface portion 44 of the first hole portion 41. The arc length A at the opening of the second hole portion 42 is set to A ≦ Ct / 4, where Ct is the total length of the side surface portion 44 in the circumferential direction of the first hole portion 41. Since the second hole portion 42 is formed in a flat slit shape, A is smaller than Ct. By setting A to ¼ or less of Ct, the opening on the first hole 41 side of the second hole 42 is closer to the central axis P1 than the length of the first hole 41 in the direction of the central axis P1. The length in the vertical direction is reduced. Thus, the fuel flows into the first hole 41 from the second hole 42 in the form of a thin liquid film.

  When the end of the second hole 42 on the first hole 41 side is extended along the central axis P2 of the second hole 42, the projection area D of the second hole 42 has a first hole. The central axis P1 of the part 41 is not included. That is, the central axis P <b> 1 of the first hole 41 is not located on the extension of the second hole 42. As a result, the fuel flows from the second hole 42 to the first hole 41 while being guided by the side surface 44 of the first hole 41. Therefore, the fuel that has flowed into the first hole 41 from the second hole 42 forms a swirling flow along the side surface 44 of the first hole 41.

  As shown in FIG. 8, in a cross section perpendicular to the central axis P1 of the first hole 41, a straight line passing through the central axis P1 of the first hole 41 and parallel to the central axis P2 of the second hole 42 is the first. This is defined as a virtual straight line L1. Moreover, the straight line which extended the wall surface 42a of the 2nd hole 42 on the side far from the 1st virtual straight line L1 in parallel with the 1st virtual straight line L1 is defined as the 2nd virtual straight line L2. Furthermore, among the tangents of the side surface portion 44 of the first hole 41 parallel to the first virtual straight line L1, the tangent on the second virtual straight line L2 side with respect to the first virtual straight line L1 is defined as a third virtual straight line L3. At this time, the second virtual straight line L2 is located between the first virtual straight line L1 and the third virtual straight line L3. That is, the second hole portion 42 is connected to the inside of the side surface portion 44 of the first hole portion 41.

  The distance d1 between the second virtual straight line L2 and the third virtual straight line L3 is set to d1 ≦ R1 × 0.2. Here, R1 is the radius of the first hole 41, that is, the distance between the first imaginary straight line L1 and the third imaginary straight line L3. The smaller the d1 is, the closer the second virtual line L2 and the third virtual line L3 are. That is, the smaller the d <b> 1, the closer the wall surface 42 a of the second hole 42 is to the tangent of the side surface 44 of the first hole 41. When d1 = 0, the wall surface 42a of the second hole portion 42 and the tangent line of the side surface portion 44 of the first hole portion 41 coincide with each other. Therefore, the fuel that has flowed into the first hole 41 from the second hole 42 flows along the side surface 44 of the first hole 41 to form a swirling flow. On the other hand, when d1 increases, the wall surface 42a of the second hole portion 42 approaches the central axis P1 of the first hole portion 41. Therefore, the fuel that has flowed into the first hole portion 41 from the second hole portion 42 is less likely to form a flow along the side surface portion 44 of the first hole portion 41, making it difficult to form a swirling flow. Therefore, d1 is preferably closer to 0, and the upper limit of d1 is set to 0.2 times the radius R1 of the first hole 41.

  As shown in FIG. 1, the length of the opening on the first hole 41 side of the second hole 42 in the direction of the central axis P1 of the first hole 41 is defined as H. The circumferential length of the side surface 44 at the end of the first hole 41 on the outlet side is B. In the present embodiment, since the first hole 41 is cylindrical, B is equal to Ct. At this time, the length H of the opening of the second hole portion 42 and the total length B of the side surface portion 44 have a relationship of B × 0.5 <H × tan α <B × 1.3. Here, α is an angle formed by the central axis P1 of the first hole portion 41 and the central axis P2 of the second hole portion 42 as described above.

  When H becomes smaller, the liquid film tends to be partially biased at the outlet of the first hole portion 41. This makes it difficult to form a uniform spray. Therefore, the lower limit of H × tan α is set to 0.5 times B. On the other hand, when H increases, the end portions of the liquid film of the belt-shaped fuel that has flowed from the second hole portion 42 into the first hole portion 41 are likely to come into contact with each other. Therefore, the liquid film becomes thicker in a streaky shape at the contact portion of the liquid film. As a result, a portion that prevents fuel atomization is formed. Therefore, the upper limit of H × tan α is set to 1.3 times B.

  By forming the nozzle hole 40 that satisfies the above-described plurality of conditions, the fuel forms a swirling flow in the first hole 41 when the fuel flows from the second hole 42 into the first hole 41. That is, the fuel that flows into the first hole 41 from the second hole 42 is guided by the side surface 44 of the first hole 41 and turns. Therefore, the fuel is injected from the outlet side of the first hole portion 41 while turning along the side surface portion 44 of the first hole portion 41.

  In the first embodiment, the nozzle hole plate 30 has a flat surface portion 33 as shown in FIG. The flat surface portion 33 is installed at the opening side end portion of the first hole portion 41. That is, the first hole portion 41 is open to the flat portion 33 on the side opposite to the closed end portion 43. An angle θ formed by the flat portion 33 and the central axis P1 of the first hole portion 41 is set to 60 ° ≦ θ ≦ 90 °.

  In the case of the first embodiment, the first hole portion 41 is inclined with respect to the plate thickness direction of the nozzle hole plate 30, that is, the axial direction of the valve body 21. Therefore, when the first hole portion 41 opens to the outlet side end surface 30 b of the nozzle hole plate 30, the length in the central axis direction of the side surface portion 44 of the first hole portion 41 becomes the outlet side end surface 30 b of the nozzle hole plate 30. The smaller the angle, the shorter the angle, and the longer the angle formed with the outlet side end face 30b of the nozzle hole plate 30, the longer the angle. That is, as for the side part 44 which forms the 1st hole part 41, the length of the central-axis P1 direction changes in the circumferential direction. Thereby, in the part where the length of the central axis direction of the side surface portion 44 is short, the fuel is injected during the turning in the first hole portion 41.

  Therefore, as shown in FIG. 1, by installing the flat surface portion 33 on the nozzle hole plate 30, when θ = 90 °, the length in the central axis P1 direction of the side surface portion 44 of the first hole portion 41 is in the circumferential direction. It becomes constant. On the other hand, for example, depending on the size of the angle α formed by the first hole 41 and the second hole 42 or the flow velocity of the fuel flowing through the first hole 41 and the second hole 42, Differences in length may occur. Therefore, the range of θ is set to 60 ° to 90 °.

Next, the operation of the injector 10 having the above configuration will be described.
When energization of the coil 62 is stopped, no magnetic attractive force is generated between the fixed core 63 and the movable core 65. Therefore, the movable core 65 moves to the opposite side of the fixed core 63 together with the needle 24 by the pressing force of the spring 18. As a result, when energization to the coil 62 is stopped, the seal portion 25 of the needle 24 is seated on the valve seat 23. Therefore, fuel is not injected from the nozzle hole 40.

  When the coil 62 is energized, the magnetic field generated in the coil 62 causes a magnetic flux to flow through the plate housing 64, the nozzle holder 20, the first magnetic part 12, the movable core 65, the fixed core 63, and the second magnetic part 14. Is formed. As a result, a magnetic attractive force is generated between the fixed core 63 and the movable core 65. When the magnetic attractive force generated between the fixed core 63 and the movable core 65 becomes larger than the pressing force of the spring 18, the movable core 65 and the needle 24 integrated with the movable core 65 move to the fixed core 63 side. As a result, the seal portion 25 of the needle 24 is separated from the valve seat 23.

  The fuel that has flowed into the injector 10 from the fuel inlet 16 is the fuel filter 17, the inner peripheral side of the inlet member 15, the inner peripheral side of the adjusting pipe 19, the inner peripheral side of the movable core 65, and the inner and outer sides of the movable core 65. Into the fuel passage 26 via the connection hole 69, between the housing 11 and the movable core 65, and between the needle 24 and the nozzle holder 20. The fuel in the fuel passage 26 flows into the nozzle hole 40 through between the valve seat 23 and the seal portion 25. Thereby, fuel is injected from the nozzle hole 40.

  When energization of the coil 62 is stopped, the magnetic attractive force between the fixed core 63 and the movable core 65 disappears. Thereby, the integral movable core 65 and the needle 24 are moved to the opposite side of the fixed core 63 by the pressing force of the spring 18. Therefore, the seal portion 25 is seated on the valve seat 23 again, and the flow of fuel between the fuel passage 26 and the nozzle hole 40 is blocked. Therefore, the fuel injection ends.

  As mentioned above, in 1st Embodiment demonstrated, the positional relationship of the 1st hole part 41 and the 2nd hole part 42 which comprise the nozzle hole 40, the shape of the 1st hole part 41 and the 2nd hole part 42, and the 1st hole The sizes of the part 41 and the second hole part 42 are set. Moreover, the 2nd hole 42 is formed in slit shape. Thereby, the fuel flowing into the first hole 41 from the second hole 42 forms a liquid film flow. Then, when the fuel flows from the second hole portion 42 into the first hole portion 41, the fuel is guided to the side surface portion 44 of the first hole portion 41 and turns inside the first hole portion 41. As a result, a turning force is applied to the fuel flowing through the first hole 41. Therefore, since the liquid film-like fuel which formed the swirl | vortex flow is injected from the nozzle hole 40, atomization of fuel can be accelerated | stimulated.

  In the first embodiment, the first hole portion 41 and the second hole portion 42 are connected at an angle α in the middle of the injection hole plate 30 in the plate thickness direction. That is, the first hole portion 41 and the second hole portion 42 are connected inside the nozzle hole plate 30. Therefore, a space for installing the second hole portion 42 is not required outside the first hole portion 41 in the radial direction. Thereby, the area which the 1st hole 41 and the 2nd hole 42 occupy is reduced. Therefore, the area occupied by the injection hole 40 is reduced, and both the downsizing of the injection hole plate 30 and the injector 10 and the atomization of fuel can be achieved at the same time. Further, since the injector 10 can be downsized, it is easy to secure a space for mounting the injector 10. Therefore, the design freedom of the injector 10 and the engine on which the injector 10 is mounted can be increased.

  In the first embodiment, the angle β between the major axes of the plurality of nozzle holes 40 of the nozzle hole plate 30 and the tangent of the circumference C centering on the central axis of the nozzle hole plate 30 is 0 °. . Therefore, the fuel flows into the second hole portion 42 of the nozzle hole 40 substantially vertically from the radially outer side of the nozzle hole plate 30. As a result, a uniform flow of fuel flows into the second hole portion 42 of the nozzle hole 40. As a result, in each nozzle hole 40 of the nozzle hole plate 30, the fuel that has passed through the second hole portion 42 forms a uniform swirling flow inside the first hole portion 41. Therefore, uniform fuel spray can be formed from the plurality of nozzle holes 40 of the nozzle hole plate 30.

  In the first embodiment, the first hole portion 41 opens in the flat portion 33 of the nozzle hole plate 30. Therefore, uniform spray is injected from the first hole 41 in the circumferential direction. As a result, the fuel is uniformly injected from the first hole 41 in a predetermined direction. Therefore, the directionality of the injected fuel can be improved.

(Second Embodiment)
An injection hole of an injector according to the second embodiment of the present invention is shown in FIG. In addition, the same code | symbol is attached | subjected to the component substantially the same as 1st Embodiment, and description is abbreviate | omitted.
In the second embodiment, as shown in FIG. 9, the second virtual straight line L2 is located on the opposite side of the third virtual straight line L3 from the first virtual straight line L1. That is, the second hole portion 42 is connected to the outside of the side surface portion 44 of the first hole portion 41. Thereby, a step 45 is formed between the first hole 41 and the second hole 42.

  The distance d2 between the second virtual straight line L2 and the third virtual straight line L3 is set to d2 ≦ R1 × 0.4. Here, R1 is the radius of the first hole 41, that is, the distance between the first imaginary straight line L1 and the third imaginary straight line L3. The smaller the d2 is, the closer the second virtual line L2 and the third virtual line L3 are. That is, as d2 becomes smaller, the wall surface 42a of the second hole portion 42 approaches the tangent line of the side surface portion 44 of the first hole portion 41. When d2 = 0, the wall surface 42a of the second hole portion 42 and the tangent line of the side surface portion 44 of the first hole portion 41 coincide with each other. Therefore, the fuel that has flowed into the first hole 41 from the second hole 42 flows along the side surface 44 of the first hole 41 to form a swirling flow.

  On the other hand, when d2 increases, the wall surface 42a of the second hole portion 42 moves away from the side surface portion 44 of the first hole portion 41. For this reason, when d2 increases, the step 45 formed between the first hole 41 and the second hole 42 expands. As a result, the fuel that has passed through the second hole 42 flows into the first hole 41 after colliding with the step 45. As a result, the energy of the fuel is reduced, and it is difficult to form a flow along the side surface portion 44 of the first hole portion 41, making it difficult to form a swirling flow. Therefore, d2 is preferably closer to 0, and the upper limit of d2 is set to 0.4 times the radius R1 of the first hole 41.

(Third embodiment)
An injection hole of an injector according to a third embodiment of the present invention is shown in FIG. In addition, the same code | symbol is attached | subjected to the component substantially the same as 1st Embodiment, and description is abbreviate | omitted.
In the third embodiment, the nozzle hole plate 30 has a tapered hole 34 at the end of the first hole 41 on the opening side, as shown in FIG. The taper hole 34 has one end connected to the first hole 41 in the axial direction and the other end connected to the cylindrical part 35. The cylindrical portion 35 is open to the flat portion 33 at the end opposite to the tapered hole portion 34. The taper hole portion 34 has an inner diameter that increases as it approaches the cylindrical portion 35 in the axial direction. As a result, the fuel that has flowed into the first hole 41 from the second hole 42 is injected through the tapered hole 34 and the cylindrical part 35 while forming a swirling flow in the first hole 41.

  The tapered hole portion 34 has an inner diameter that increases as it approaches the cylindrical portion 35 in the axial direction. When the fuel that has formed a swirling flow in the first hole portion 41 flows into the tapered hole portion 34, the fuel expands radially outward along the side surface portion of the tapered hole portion 34. The swirling fuel has an axial velocity component and a circumferential velocity component. Since the angular velocity of the circumferential speed component of the fuel is constant, when the diameter of the fuel that forms the swirling flow in the tapered hole portion 34 is increased, the axial velocity component is relatively increased. As a result, on the outlet side of the tapered hole portion 34, that is, on the cylindrical portion 35 side, the axial velocity component is relatively larger than the circumferential velocity component. Thereby, at the exit of the nozzle hole 40, that is, the opening side of the cylindrical portion 35, the straightness of the fuel is improved by a large velocity component in the axial direction. Further, the diameter of the fuel is difficult to expand due to the reduced velocity component in the circumferential direction. As a result, the fuel sprayed from the nozzle hole 40 has a small spray angle. When the spray angle is reduced, the collision between the sprays injected from the adjacent nozzle holes 40 of the nozzle hole plate 30 is reduced. Therefore, an increase in the particle size of the spray accompanying the spray collision is suppressed, and atomization can be promoted.

(Other embodiments)
An injection hole of an injector according to another embodiment of the present invention is shown in FIGS. In addition, the same code | symbol is attached | subjected to the component substantially the same as 1st Embodiment, and description is abbreviate | omitted.
In other embodiments shown in FIGS. 11 and 12, the cross-sectional shape of the second hole portion 42 constituting the nozzle hole 40 is different from that of the first embodiment. As described in the first embodiment, the shape of the cross section perpendicular to the central axis P2 of the second hole portion 42 and the shape of the opening on the inlet side end face 30a are flat slits. Therefore, the second hole portion 42 does not need to have a rectangular cross-sectional shape as long as it has a flat slit shape.

  The cross section of the second hole portion 42 is an ellipse as shown in FIG. 11 (A), a wedge shape as shown in FIG. 11 (B), and a trapezoid as shown in FIG. 11 (C) or FIG. 12 (A). May be. Further, the second hole portion 42 may have a configuration in which a plurality of hole portions having a circular cross section are linearly arranged as shown in FIG. Further, the second hole portion 42 may have a configuration in which a plurality of circular hole portions are arranged so as to overlap each other as shown in FIG. Each of the second hole portions 42 shown in FIGS. 11 and 12 has a slit shape having a major axis and a minor axis. Furthermore, you may apply combining the cross-sectional shape of the 2nd hole part 42 shown to FIG. 11 and FIG.

  In the above-described plurality of embodiments, the example in which five nozzle holes 40 are arranged in the nozzle hole plate 30 has been described. However, the number of nozzle holes 40 is not limited to five as long as it is one or more. The number of nozzle holes 40 can be appropriately selected according to the engine to which the injector 10 is applied.

It is a figure which shows the nozzle hole of the injector by 1st Embodiment of this invention, Comprising: (A) is the schematic diagram seen from the valve body side, (B) is sectional drawing cut | disconnected by the BB line of (A). . It is sectional drawing which shows the injector by 1st Embodiment of this invention. It is sectional drawing to which the vicinity of the nozzle hole of the injector by 1st Embodiment of this invention was expanded. It is a figure which shows the nozzle hole plate of the injector by 1st Embodiment of this invention, Comprising: It is the schematic diagram seen from the valve body side. It is a schematic perspective view which shows the nozzle hole of the injector by 1st Embodiment of this invention. It is a figure which shows the modification of the nozzle hole plate of the injector by 1st Embodiment of this invention, Comprising: It is the schematic diagram seen from the valve body side. It is a schematic diagram which shows the cross section cut | disconnected by the VII-VII line of FIG. It is a schematic diagram which shows the cross section cut | disconnected by the VII-VII line of FIG. It is a figure which shows the nozzle hole of the injector by 2nd Embodiment of this invention, Comprising: It is a figure corresponding to FIG. 8 of 1st Embodiment. It is a figure which shows the nozzle hole of the injector by 3rd Embodiment of this invention, Comprising: It is a figure corresponding to FIG. 1 (B) of 1st Embodiment. It is a figure which shows the nozzle hole of the injector by other embodiment of this invention, Comprising: It is a figure corresponding to FIG. 1 (A) of 1st Embodiment. It is a figure which shows the nozzle hole of the injector by other embodiment of this invention, Comprising: It is a figure corresponding to FIG. 1 (A) of 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Injector (fuel injection valve), 21 Valve body, 22 Inner wall, 23 Valve seat, 24 Needle (valve member), 26 Fuel passage, 30 Injection hole plate (injection hole formation member), 33 Planar part, 34 Tapered hole part, 35 cylindrical portion, 40 nozzle hole, 41 first hole portion, 42 second hole portion, 43 closed end portion, 44 side surface portion

Claims (13)

A valve body having a valve seat on an inner wall forming a fuel passage;
An injection hole forming member installed on the downstream side of the fuel flow with respect to the valve seat, and having a plurality of injection holes for injecting fuel flowing through the fuel passage;
A valve member that shuts off fuel injection from the nozzle hole by sitting on the valve seat and allows fuel injection from the nozzle hole by separating from the valve seat;
The nozzle hole has a first hole portion whose one end portion is open on a surface opposite to the valve body of the nozzle hole forming member and whose other end portion is closed inside the nozzle hole forming member. A slit-like second hole having one end opened on the valve body side surface of the nozzle hole forming member and the other end opened in the first hole,
An angle α formed by the central axis of the first hole and the central axis of the second hole satisfies 20 ° ≦ α <80 °.   The end of the second hole on the first hole side is at least one of a side surface of the first hole or a closed end that closes the valve body side of the first hole. The fuel injection valve according to claim 1, wherein the fuel injection valve is open.   In the cross section perpendicular to the central axis of the first hole portion, the second hole portion opened to the first hole portion has an overall length of a circular arc in the circumferential direction of the first hole portion. The fuel injection valve according to claim 1 or 2, wherein the fuel injection valve is 1/4 or less of a total length in a circumferential direction of the portion.   4. The fuel injection valve according to claim 3, wherein a central axis of the first hole is not included in a projection region in which an end of the second hole on the first hole side is extended. 5. In a cross section perpendicular to the central axis of the first hole portion, a straight line passing through the central axis of the first hole portion and parallel to the central axis of the second hole portion is defined as a first imaginary straight line. A straight line obtained by extending the wall surface of the second hole portion on the far side in parallel with the first virtual straight line is defined as a second virtual straight line, and the first of the tangent lines of the wall surface of the first hole portion parallel to the first virtual straight line. When the tangent on the second virtual straight line side than the one virtual straight line is a third virtual straight line,
The fuel injection valve according to claim 4, wherein the second virtual straight line is located between the first virtual straight line and the third virtual straight line. When the radius of the first hole is R1,
6. The fuel injection valve according to claim 5, wherein a distance d1 between the second virtual line and the third virtual line is d1 ≦ R1 × 0.2. In a cross section perpendicular to the central axis of the first hole portion, a straight line passing through the central axis of the first hole portion and parallel to the central axis of the second hole portion is defined as a first imaginary straight line. A straight line obtained by extending the wall surface of the second hole portion on the far side in parallel with the virtual straight line is defined as a second virtual straight line, and the first virtual line is tangent to the wall surface of the first hole parallel to the first virtual straight line. When the tangent on the second virtual straight line side than the straight line is a third virtual straight line,
5. The fuel injection valve according to claim 4, wherein the second virtual straight line is located on the opposite side of the third virtual straight line from the first virtual straight line. When the radius of the first hole is R1,
8. The fuel injection valve according to claim 7, wherein a distance d2 between the second virtual line and the third virtual line is d2 ≦ R1 × 0.4. The length of the opening on the first hole side of the second hole in the central axis direction of the first hole is H, and the total length in the circumferential direction of the side surface at the end of the first hole on the opening side Is B,
9. The fuel injection valve according to claim 1, wherein B × 0.5 <H × tan α <B × 1.3. The nozzle hole forming member has a flat surface portion that is open at an end opposite to the closed end portion of the first hole portion,
10. The fuel injection valve according to claim 1, wherein an angle θ formed between the planar portion and the central axis of the first hole portion is 60 ° ≦ θ ≦ 90 °.   10. The fuel injection valve according to claim 1, wherein the injection hole forming member has a tapered hole portion connected to an opening side end portion of the first hole portion. The nozzle hole forming member is located on the opposite side of the tapered hole portion from the first hole portion, on the end portion of the tapered hole portion opposite to the first hole portion, or on the first hole of the tapered hole portion. Having a flat part that is open at the end of the cylindrical part connected to the opposite side of the part,
The fuel injection valve according to claim 11, wherein an angle θ between the planar portion and the central axis of the first hole portion is 60 ° ≦ θ ≦ 90 °. The nozzle hole forming member has a plurality of the nozzle holes,
The plurality of nozzle holes are arranged on a circumference centered on a central axis of the valve body,
When the angle formed by the long axis of the second hole in a cross section perpendicular to the central axis of the second hole and the tangent of the circumference where the plurality of nozzle holes are arranged is β,
The fuel injection valve according to claim 1, wherein 0 ° ≦ β ≦ 45 °.

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