JP2017031980A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve which can improve homogeneity of air-fuel mixture in a combustion chamber by supplying a proper amount of fuel at each place in the combustion chamber in a state of being easily mixed with air.SOLUTION: In a fuel injection valve 10, a plurality of injection holes 155 are provided for injecting a fuel toward a combustion chamber 90 of an internal combustion engine. Injection axes 159 of the plurality of injection holes 155 face different directions from each other respectively. An intake side injection hole 157 for orienting the intake side of the combustion chamber 90 is a straight-shaped injection hole for extending an inner peripheral wall surface 157a along the injection hole axis 159b. On the other hand, an exhaust side injection hole 156 for orienting the exhaust side of the combustion chamber 90 is an enlarged taper-shaped injection hole for separating an inner peripheral wall surface 156a from the injection hole axis 159a toward an outlet side opening 155b_e.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel injection valve that injects fuel into a combustion chamber provided in an internal combustion engine.

  The fuel injection valve is formed with a plurality of injection holes for injecting fuel into the combustion chamber. As one type of such fuel injection valve, for example, in the configuration disclosed in Patent Document 1, the inner diameter of an injection hole directed to the intake side of the combustion chamber (hereinafter referred to as “intake side injection hole”) is directed to the exhaust side of the combustion chamber. It is made smaller than the inner diameter of the nozzle hole (hereinafter referred to as “exhaust-side nozzle hole”). With such a configuration, the mixture of air and fuel is homogenized in the combustion chamber.

Japanese Patent No. 4069750

  However, in the configuration in which the intake side injection hole has a smaller diameter than the exhaust side injection hole as in the fuel injection valve disclosed in Patent Document 1, the penetration force of the fuel spray injected from the intake side injection hole is It becomes lower than the penetration force of the fuel spray by the nozzle hole. Therefore, in an actual internal combustion engine, it is difficult for the fuel to reach the entire high-speed air flowing on the intake side of the combustion chamber. On the other hand, the fuel spray from the exhaust-side nozzle hole having a diameter larger than that of the intake-side nozzle hole can penetrate through the air on the exhaust side of the combustion chamber having a low flow rate by having a high penetration force. As a result, the fuel becomes difficult to mix with air.

  In addition, in the fuel injection valve of Patent Document 1, the penetration force of the fuel spray is adjusted by changing the inner diameters of the intake side injection hole and the exhaust side injection hole. Therefore, the fuel flow rate flowing through the intake side nozzle hole must be smaller than the fuel flow rate flowing through the exhaust side nozzle hole. Therefore, even if it tries to correct the deviation of the amount of fuel injected by devising the number and arrangement of the intake side nozzle holes and exhaust side nozzle holes, it is realized until the optimum fuel amount is supplied in the direction of the direction of each nozzle hole. It was difficult.

  The present invention has been made in view of such a problem, and an object of the present invention is to supply an appropriate amount of fuel to various locations in the combustion chamber in a state in which it is easily mixed with air. An object of the present invention is to provide a fuel injection valve capable of improving homogeneity.

  In order to achieve the above object, a first invention is a fuel injection valve that injects fuel from a plurality of injection holes (155, 255) into a combustion chamber (90) provided in an internal combustion engine, For the plurality of nozzle holes, the nozzle hole axes (159, 259) defining the individual directing directions are directed in different directions, and combustion is performed according to the posture of the nozzle hole axis (159b, 259b) among the plurality of nozzle holes. The at least one intake side nozzle hole (157) directed to the intake side of the chamber has a straight shape that extends the inner peripheral wall surface (157a) along the nozzle hole axis while maintaining a reference inner diameter (Dn_i) serving as a reference. Among the plurality of nozzle holes, at least one exhaust-side nozzle hole (156) directed to the exhaust side of the combustion chamber according to the attitude of the nozzle hole axis (159a, 259a) is an outlet-side opening exposed to the combustion chamber. Head to (155b_e) Therefore, by separating the inner peripheral wall surface (156a) from the nozzle hole axis, the flow path area is enlarged from the reference inner diameter (Dn_e) to the opening on the outlet side, and a plurality of nozzle holes A jet that forms a sack portion (152) that forms a sac chamber (154) that communicates with the first chamber, a first region (167) that penetrates the intake side nozzle hole, and a second region (166) that penetrates the exhaust side nozzle hole Hole openings (155a, 255a) facing the sac chambers at equal intervals, the wall thickness of the first region and the second wall. The wall thickness of the region differs from each other by being defined to correspond to the flow path length of the intake side nozzle hole and the flow path length of the exhaust side nozzle hole, and the wall thickness of the first region is different from the second region It is characterized by being thinner than the wall thickness.

  In this invention, since the intake side injection hole directed toward the intake side of the combustion chamber has a straight shape, the fuel spray injected from the intake side injection hole has a high penetration force. By increasing the penetration force of the fuel spray by the intake side injection hole in this way, it becomes possible to spread the fuel over the entire air having a high flow velocity flowing through the intake side of the combustion chamber.

  On the other hand, because the exhaust side injection hole directed to the exhaust side of the combustion chamber has an enlarged shape, the penetration force of the fuel spray injected from the exhaust side injection hole is greater than the penetration force of the fuel spray from the intake side injection hole. Lower. Therefore, the fuel spray injected from the exhaust side injection hole can be mixed with the whole air without penetrating through the air on the exhaust side of the combustion chamber whose flow velocity is slower than that of the intake side.

  In addition, in the above-described configuration, the penetration force of the fuel spray is adjusted by forming the intake side injection hole and the exhaust side injection hole in different shapes. Therefore, the flow rate of fuel flowing through each of the intake-side nozzle holes and the exhaust-side nozzle holes can be adjusted as appropriate during design. The plurality of nozzle holes can supply an optimum amount of fuel in each directivity direction.

  According to the above, since the fuel injection valve can supply an appropriate amount of fuel to various places in the combustion chamber in a state where it can be easily mixed with air, the homogeneity of the air-fuel mixture in the combustion chamber can be improved.

  Note that the reference numbers in the parentheses are merely examples of correspondences with specific configurations in the embodiments to be described later in order to facilitate understanding of the present invention, and limit the scope of the present invention. It is not a thing.

It is a figure which shows the state installed in the gasoline engine about the fuel injection valve which performs center injection by 1st embodiment of this invention. It is the figure which looked at the ceiling surface side of the combustion chamber from the arrow II of FIG. 1, Comprising: It is a schematic diagram which shows typically the positional relationship of a fuel injection valve and its surrounding structure. It is sectional drawing which shows the structure of a fuel injection valve. It is sectional drawing which expands and shows the vicinity of a sack part, Comprising: It is the IV-IV sectional view taken on the line of FIG. It is the VV sectional view taken on the line of FIG. It is sectional drawing which expands further and shows the vicinity of an exhaust side nozzle hole. It is sectional drawing which expands and shows the vicinity of an intake side injection hole further. It is a figure which shows the correlation with the L / D value in the enlarged taper-shaped nozzle hole, and the particle size of a spray, and the correlation with a L / D value and a spray shrinkage rate, respectively. It is sectional drawing which expands and shows the area | region IX of FIG. It is a figure which shows the correlation with the corner radius of the edge part which divides the inlet side opening of a nozzle hole, and the particle size of spray. It is a figure which shows the state installed in the gasoline engine about the fuel injection valve which performs side injection by 2nd embodiment of this invention. It is the figure which looked at the ceiling surface side of the combustion chamber from arrow XII of FIG. 11, Comprising: It is a schematic diagram which shows typically the positional relationship of a fuel injection valve and its surrounding structure. It is a figure which shows arrangement | positioning and the directing direction of each nozzle hole. It is a figure which shows the modification 1 of FIG. It is a figure which shows the modification 2 of FIG. It is a figure which shows the modification 3 of FIG. It is a figure which shows the modification 4 of FIG. It is a figure which shows the modification 5 of FIG. It is a figure which shows the modification 6 of FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. Moreover, not only the combination of the configurations explicitly described in the description of each embodiment, but also the configuration of a plurality of embodiments can be partially combined even if they are not explicitly described, as long as there is no problem in the combination. And the combination where the structure described in several embodiment and the modification is not specified shall also be disclosed by the following description.

(First embodiment)
A fuel injection valve 10 according to the first embodiment of the present invention shown in FIGS. 1 and 2 is installed in a gasoline engine as an internal combustion engine. The fuel injection valve 10 injects fuel from a plurality of injection holes 155 toward a combustion chamber 90 provided in the gasoline engine. The combustion chamber 90 is partitioned by a cylinder block, a cylinder head, a piston 94, and the like. In addition to the fuel injection valve 10, the cylinder head is provided with two intake valves 93, two exhaust valves 92, a spark plug 91, and the like. The fuel injection valve 10 and the spark plug 91 are installed adjacent to each other in the center of each intake valve 93 and each exhaust valve 92. The fuel injection valve 10 is closer to the two intake valves 93 than the spark plug 91, and the tip portion where the injection hole 155 is formed is exposed in the combustion chamber 90. The spark plug 91 is closer to the two exhaust valves 92 than the fuel injection valve 10, and the tip portion that generates flame nuclei is exposed in the combustion chamber 90. Note that FIG. 1 shows an intake valve 93 and an exhaust valve 92 when the valve is closed for easy explanation.

  As shown in FIG. 3, the fuel injection valve 10 includes a valve body 11, a fixed core 20, a movable core 30, a valve member 40, an elastic member 50, and a drive unit 60.

  The valve body 11 includes a core housing 12, an inlet member 13, a nozzle holder 14, a nozzle body 15, and the like. The core housing 12 is formed in a cylindrical shape, and includes a first magnetic portion 12a, a nonmagnetic portion 12b, and a second magnetic portion 12c in order from one end side in the axial direction toward the other end side. The magnetic portions 12a and 12c made of a magnetic material and the nonmagnetic portion 12b made of a nonmagnetic material are coupled by laser welding or the like. With such a coupling structure, the nonmagnetic portion 12b prevents a short circuit of magnetic flux between the first magnetic portion 12a and the second magnetic portion 12c.

  A cylindrical inlet member 13 is fixed to the axial end of the second magnetic portion 12c opposite to the nonmagnetic portion 12b. The inlet member 13 forms a fuel inlet 13a to which fuel is supplied from a fuel pump (not shown). In order to filter the fuel supplied to the fuel inlet 13 a and guide it into the core housing 12 on the downstream side, in the first embodiment, a fuel filter 16 is fixed to the inner peripheral side of the inlet member 13.

  A nozzle body 15 is fixed to an axial end of the first magnetic portion 12a opposite to the nonmagnetic portion 12b via a nozzle holder 14 formed in a cylindrical shape by a magnetic material. The nozzle body 15 is formed in a bottomed cylindrical shape, and a fuel passage 17 is formed on the inner peripheral side in cooperation with the core housing 12 and the nozzle holder 14. As shown in FIG. 4, the nozzle body 15 has a valve seat portion 150 and a sack portion 152.

  The valve seat portion 150 forms a valve seat surface 151 by an inner peripheral surface of a tapered surface that is reduced in diameter by a constant diameter reduction rate toward the fuel downstream side in the axial direction. The sack portion 152 is adjacent to the fuel downstream side of the valve seat portion 150 that forms the fuel passage 17 by the valve seat surface 151. The sack portion 152 forms a cylindrical hole-shaped recess 153 that opens toward the fuel passage 17 on the upstream side of the fuel. A nozzle hole 155 communicating with the sac chamber 154 is formed on the inner surface of the recess 153 forming the sac chamber 154. As shown in FIGS. 4 and 5, a plurality of nozzle holes 155 of the first embodiment are provided around the central axis 18 of the recess 153 at intervals. Each inlet-side opening 155 a of each nozzle hole 155 is located on the same virtual circle 19 around the central axis 18. Each nozzle hole 155 is inclined toward the outer peripheral side of the recess 153 toward the respective outlet side openings 155b on the fuel downstream side.

  The fixed core 20 shown in FIG. 3 is formed in a cylindrical shape by a magnetic material, and is coaxially fixed to the inner peripheral surfaces of the nonmagnetic portion 12 b and the second magnetic portion 12 c in the core housing 12. The fixed core 20 is provided with a through hole 20a that penetrates the central portion in the radial direction in the axial direction. The fuel that flows into the through hole 20a from the fuel inlet 13a through the fuel filter 16 flows out of the through hole 20a toward the movable core 30 that is the downstream side.

  The movable core 30 is formed of a magnetic material in a stepped cylindrical shape, is coaxially disposed on the inner peripheral side of the core housing 12, and faces the fixed core 20 on the upstream side of the fuel in the axial direction. The movable core 30 is guided by the inner peripheral wall of the nonmagnetic portion 12b of the core housing 12, so that the movable core 30 can be accurately reciprocated on both sides in the axial direction. The movable core 30 has a first through hole 30a that penetrates the radial center portion in the axial direction and a second through hole 30b that penetrates the axial middle portion in the radial direction and communicates with the first through hole 30a. , Provided. The fuel flowing out from the through hole 20a of the fixed core 20 flows into the first through hole 30a of the movable core 30 on the downstream side, and flows out from the second through hole 30b to the fuel passage 17 in the core housing 12. Become.

  The valve member 40 is formed in a needle shape having a circular cross section by a non-magnetic material, and is coaxially disposed in the fuel passage 17 formed in the valve body 11 on the inner peripheral side by the elements 12, 14, 15. ing. The axial end of the upstream side of the fuel in the valve member 40 is coaxially fixed to the inner peripheral surface of the first through hole 30 a of the movable core 30. As shown in FIGS. 3 and 4, the axial end portion on the downstream side of the fuel in the valve member 40 forms an abutting portion 41 whose diameter decreases toward the downstream side of the fuel in the axial direction. The contact portion 41 is opposed to the surface 151 so as to be able to contact. The valve member 40 causes the contact portion 41 to be separated from and seated on the valve seat surface 151 by displacement along a predetermined central axis 18. Thus, the fuel injection from the nozzle hole 155 is interrupted. Specifically, when the valve member 40 is opened so that the contact portion 41 is separated from the valve seat surface 151, fuel flows from the fuel passage 17 into the sac chamber 154 and is injected from each nozzle hole 155 into the combustion chamber. The On the other hand, when the valve member 40 is closed so that the contact portion 41 is seated on the valve seat surface 151, the fuel injection from each nozzle hole 155 to the combustion chamber is blocked.

  As shown in FIG. 3, the elastic member 50 is made of a metal compression coil spring, and is accommodated coaxially on the inner peripheral side of the through hole 20 a provided in the fixed core 20. One end of the elastic member 50 is locked to the axial end of the adjusting pipe 22 fixed to the inner peripheral surface of the through hole 20a. The other end of the elastic member 50 is locked to the inner surface of the first through hole 30 a of the movable core 30. With this locking structure, the elastic member 50 is elastically deformed by being compressed between the elements 22 and 30 sandwiching the elastic member 50. Therefore, the restoring force generated by the elastic deformation of the elastic member 50 becomes an urging force for urging the movable core 30 together with the valve member 40 toward the fuel downstream side.

  The drive unit 60 includes a coil 61, a resin bobbin 62, a magnetic yoke 63, a connector 64, and the like. The coil 61 is formed by winding a metal wire around a resin bobbin 62, and a magnetic yoke 63 is disposed on the outer peripheral side thereof. The coil 61 is coaxially fixed to the outer peripheral surfaces of the nonmagnetic portion 12 b and the second magnetic portion 12 c on the outer peripheral side of the fixed core 20 in the core housing 12 via a resin bobbin 62. The coil 61 is electrically connected to an external control circuit (not shown) via a terminal 64a provided on the connector 64, and energization is controlled by the control circuit.

  Here, when the coil 61 is excited by energization, the magnetic yoke 63, the nozzle holder 14, the first magnetic part 12a, the movable core 30, the fixed core 20, and the second magnetic part 12c form a magnetic circuit together. Flows. As a result, a magnetic attractive force that attracts the movable core 30 toward the fixed core 20 on the upstream side of the fuel is generated between the movable core 30 and the fixed core 20. On the other hand, when the coil 61 is demagnetized by stopping energization, the magnetic flux does not flow in the above-described magnetic circuit, so that the magnetic attractive force disappears between the movable core 30 and the fixed core 20.

  In the valve opening operation of the fuel injection valve 10 configured as described above, the magnetic attractive force acts on the movable core 30 by starting energization of the coil 61. Then, the movable core 30 together with the valve member 40 moves to the fixed core 20 side against the restoring force of the elastic member 50, and comes into contact with the fixed core 20 and stops. As a result, since the contact portion 41 is separated from the valve seat surface 151, fuel is injected from each nozzle hole 155.

  In the valve closing operation of the fuel injection valve 10 after such valve opening operation, the magnetic attraction force acting on the movable core 30 disappears by stopping the energization of the coil 61. Then, the movable core 30 together with the valve member 40 moves to the urging side by the restoring force of the elastic member 50, thereby bringing the valve member 40 into contact with the valve seat surface 151 and stopping. As a result, since the contact portion 41 is seated on the valve seat surface 151, fuel injection from each nozzle hole 155 is stopped.

  Next, the configuration near the recess 153 shown in FIGS. 4 and 5 will be described in detail. The bottom wall 160 of the recess 153 is formed to face the valve member 40 having the contact portion 41 seated on the valve seat surface 151 with a distance. With such a facing structure, a sac chamber 154 communicating with each nozzle hole 155 is formed between the tip surface 42 of the valve member 40 and the bottom wall 160 when the contact portion 41 is seated on the valve seat surface 151. . The volume of the sac chamber 154 is regulated so as to suppress the entry of foreign matter (contamination) in the fuel.

  A central surface portion 161 and a tapered surface portion 162 are formed on the bottom surface of the bottom wall 160. Further, a connection surface 163 is formed on the outer peripheral side of the bottom surface. The central surface portion 161 is a flat surface formed in a perfect circle shape, and is positioned coaxially with the central axis 18. The taper surface portion 162 is formed in a tapered surface shape whose diameter is reduced at a constant diameter reduction rate toward the center surface portion 161 on the fuel downstream side in the axial direction. The connection surface 163 is formed in a concave curved surface shape whose diameter reduction rate increases toward the downstream side of the fuel, and connects the outer peripheral side of the tapered surface portion 162 and the inner peripheral side of the valve seat surface 151.

  A plurality (six) of nozzle holes 155 are formed in the bottom wall 160 described above. Each nozzle hole 155 extends along each nozzle hole axis 159. Each nozzle hole axis 159 indicates the central axis of each nozzle hole 155, and defines the directing direction of each nozzle hole 155, that is, the injection direction of the fuel spray (see the thick arrow in FIG. 5). Each nozzle hole axis 159 is directed in a different direction, and intersects the central axis 18 of the sac chamber 154 or has a twisted positional relationship. In a state where the fuel injection valve 10 is mounted on the gasoline engine, the three injection hole axis lines 159a are inclined toward the exhaust valve 92 side from the central axis line 18 in the combustion chamber 90 shown in FIG. As a result, the three nozzle hole axes 159 a are defined to pass through the space between the top surface of the piston 94 and the exhaust valve 92 in the combustion chamber 90. Of the plurality of nozzle holes 155 shown in FIGS. 4 and 5, three whose orientation directions are defined on the exhaust side of the combustion chamber 90 (see FIG. 1) by the orientation of the nozzle axis 159 a are oriented on the exhaust side. This is an exhaust side injection hole 156 (see also FIG. 6).

  On the other hand, the other three nozzle hole axes 159b are inclined more toward the intake valve 93 than the center axis 18 in the combustion chamber 90 shown in FIG. As a result, the three nozzle hole axes 159 b are defined to pass through the space between the top surface of the piston 94 and the intake valve 93 in the combustion chamber 90. Of the plurality of nozzle holes 155 shown in FIGS. 4 and 5, three whose orientation directions are defined on the intake side of the combustion chamber 90 (see FIG. 1) by the attitude of the nozzle axis 159 b are oriented on the exhaust side. This is the intake side injection hole 157 (see also FIG. 7).

  The exhaust side injection hole 156 shown in FIG. 6 is an injection hole that supplies fuel to the exhaust side space of the combustion chamber 90. The exhaust-side nozzle hole 156 is an enlarged taper-shaped nozzle hole that expands the flow path area from the inlet-side opening 155a_e exposed to the sac chamber 154 toward the outlet-side opening 155b_e exposed to the combustion chamber 90. The inner peripheral wall surface 156a that defines the exhaust side injection hole 156 is formed in a tapered surface shape that expands from the reference inner diameter Dn_e that becomes the reference of the inner diameter of the flow path toward the downstream side of the fuel. Therefore, the inner peripheral wall surface 156a is separated from the nozzle hole axis 159a toward the outlet side opening 155b_e. In the longitudinal section of the exhaust-side nozzle hole 156 including the nozzle hole axis 159a, the taper angle θn of the inner peripheral wall surface 156a is in the range of 10 ° to 30 °.

  Assuming that the flow path length of the exhaust side injection hole 156 is Ln_e, a value obtained by dividing the flow path length Ln_e by the reference inner diameter Dn_e (hereinafter referred to as “L / D value”) is a spray in the fuel injection valve 10. Is related to the atomization characteristics and the shrinkage rate of the spray. Hereinafter, the setting range of the L / D value in the exhaust nozzle hole 156 will be described based on FIG. 8 with reference to FIG. Note that the contraction rate of the spray in the exhaust-side injection hole 156 is defined as an angle θ2_e from the central axis 18 to the injection hole axis 159a and an angle θ1_e from the central axis 18 to the outer edge OB of the spray in the longitudinal section including the injection hole axis 159a. The value divided by.

  As shown in FIG. 8A, the atomization characteristics of the spray are best at a specific L / D value at which the spray particle size is minimized. The L / D value of the exhaust side injection hole 156 is defined within a range in which the particle size of the spray does not exceed a predetermined maximum particle size based on the requirements of the gasoline engine. In an enlarged tapered nozzle hole such as the exhaust nozzle hole 156, the upper limit value of L / D is 3.0.

  Further, the longer the flow path of the nozzle hole, the more the fuel flowing through the nozzle hole is rectified. Therefore, the spray sprayed becomes easy to fly along the nozzle hole axis. As a result, as shown in FIG. 8B, the contraction rate of the spray increases as the L / D value increases. When the L / D value exceeds a specific value, the spray contraction rate becomes substantially constant. The L / D value of the exhaust side injection hole 156 is defined to be equal to or greater than a value at which the increase in the spray contraction rate is saturated. In the enlarged tapered nozzle hole such as the exhaust nozzle hole 156, the value at which the increase in the spray contraction rate is saturated is 2.0.

  Based on the reason described above, the L / D value of the exhaust-side nozzle hole 156 is in the range of 2.0 to 3.0.

  The intake side injection hole 157 shown in FIG. 7 is an injection hole for supplying fuel to the intake side space of the combustion chamber 90. The intake-side injection hole 157 is a straight injection hole that maintains the flow path area from the inlet-side opening 155a_i exposed to the sac chamber 154 to the outlet-side opening 155b_i exposed to the combustion chamber 90. An inner peripheral wall surface 157a that defines the intake side injection hole 157 is formed in a cylindrical surface shape having a reference inner diameter Dn_i, and extends along the injection hole axis 159b.

  When the flow path length of the intake side injection hole 157 is Ln_i, the L / D value of the intake side injection hole 157 obtained by dividing the flow path length Ln_i by the reference inner diameter Dn_i is 1.5 or more. ing. This lower limit value of L / D is a value at which the increase in the spray contraction rate is saturated in a straight-shaped injection hole such as the intake-side injection hole 157. Note that the contraction rate of the spray in the intake-side injection hole 157 is defined as an angle θ2_i from the central axis 18 to the injection hole axis 159b and an angle θ1_i from the central axis 18 to the outer edge OB of the spray in the longitudinal section including the injection hole axis 159b. The value divided by.

  As shown in FIGS. 7 and 8, in the first embodiment, the reference inner diameter Dn_i of the intake side injection hole 157 is substantially the same as the reference inner diameter Dn_e of the exhaust side injection hole 156. Accordingly, the area A_i of the inlet side opening 155a_i in the intake side nozzle hole 157 is aligned with the area A_e of the inlet side opening 155a_e in the exhaust side nozzle hole 156. The inlet-side openings 155a_i and 155a_e of the intake-side injection hole 157 and the exhaust-side injection hole 156 are arranged at equal intervals on the same virtual circle 19 (see FIG. 5) defined around the central axis 18.

  Further, in the bottom wall 160, a portion that penetrates the intake side injection hole 157 is a first region 167, and a portion that penetrates the exhaust side injection hole 156 is a second region 166. As described above, when the reference inner diameters Dn_i and Dn_e are aligned and the L / D values of the nozzle holes 157 and 156 are set to different values, the channel lengths Ln_i and Ln_e are different from each other. In order to compensate for the difference in the flow path lengths, the wall thickness of the first region 167 is defined to correspond to the flow channel length Ln_i of the intake side injection hole 157, and the wall thickness of the second region 166 is It is defined to correspond to the flow path length Ln_e of the exhaust side injection hole 156. Specifically, the wall thickness of the first region 167 along the nozzle hole axis 159b is different from the wall thickness of the second region 166 along the nozzle hole axis 159a. Is also thinned.

  The exhaust side injection hole 156 and the intake side injection hole 157 are formed in the bottom wall 160 by laser processing. By adopting such a processing method, each of the edge portions 164 that define the inlet side openings 155a_i and 155a_e in the longitudinal sections including the respective injection hole axis lines 159b and 159a for the intake side injection hole 157 and the exhaust side injection hole 156. (See also FIG. 9). Similarly, the corner radii of the edge portions 165 that define the outlet openings 155b_i and 155b_e are also minute. Specifically, the corner radii of the edge portions 164 and 165 on the entrance side and the exit side are both 10 micrometers or less.

  In the first embodiment described so far, since the intake side injection hole 157 directed to the intake side of the combustion chamber 90 has a straight shape, the fuel spray injected from the intake side injection hole 157 has a high penetration force (penetration). ). Thus, by increasing the penetration force of the fuel spray by the intake side injection hole 157, it becomes possible to spread the fuel over the entire air having a high flow velocity flowing through the intake side of the combustion chamber 90.

  On the other hand, since the exhaust side injection hole 156 directed to the exhaust side of the combustion chamber 90 has an enlarged shape, the penetration force of the fuel spray injected from the exhaust side injection hole 156 is reduced by the fuel spray by the intake side injection hole 157. It will be lower than the penetrating power. Therefore, the fuel spray injected from the exhaust side injection hole 156 can be mixed with the whole air without penetrating the air on the exhaust side of the combustion chamber 90 whose flow velocity is slower than that of the intake side.

  In addition, in the above-described configuration, the penetration force of the fuel spray is adjusted by forming the intake side injection hole 157 and the exhaust side injection hole 156 in different shapes. Therefore, the flow rate of fuel flowing through each of the intake-side injection hole 157 and the exhaust-side injection hole 156 can be appropriately adjusted at the time of design, and can also be aligned with each other. Therefore, each nozzle hole 155 can supply an optimum amount of fuel in each direction.

  As described above, the fuel injection valve 10 can supply an appropriate amount of fuel to various locations in the combustion chamber 90 in a state where it can be easily mixed with air. Therefore, the homogeneity of the air-fuel mixture in the combustion chamber 90 is improved.

  In addition, in the first embodiment, the L / D value of the exhaust-side nozzle hole 156 having an enlarged taper shape is optimized. Therefore, the fuel spray injected from the exhaust side injection hole 156 can fly while maintaining the spread in the atomized state, so that it becomes easier to mix with the entire air on the exhaust side of the combustion chamber 90. Similarly, since the L / D value of the straight-shaped intake side injection hole 157 is optimized, the fuel spray injected from the intake side injection hole 157 can be prevented from contracting. Therefore, the fuel spray from the intake side nozzle hole 157 is more easily spread over the entire air on the intake side of the combustion chamber 90.

  Further, in the first embodiment, by providing a difference in the wall thicknesses of the first region 167 and the second region 166 in the bottom wall 160, the flow path lengths Ln_i of the exhaust side injection hole 156 and the intake side injection hole 157, The difference in Ln_e is absorbed. As described above, when the suitable flow path lengths Ln_i and Ln_e in the respective nozzle holes 156 and 157 are different from each other, a configuration in which the wall thicknesses of the first region 167 and the second region 166 are different is adopted. By doing so, complementation of each flow path length Ln_i and Ln_e is easily realizable.

  Furthermore, in the first embodiment, the areas A_i and A_e of the inlet side openings 155a of the intake side injection holes 157 and the exhaust side injection holes 156 are aligned with each other. Therefore, the flow rate of the fuel flowing through each of the intake side injection hole 157 and the exhaust side injection hole 156 can be aligned with each other. As a result, a substantially equal amount of fuel is supplied in each direction directed by each nozzle hole 155. Therefore, the homogeneity of the air-fuel mixture at various locations in the combustion chamber 90 can be further improved.

  In addition, in the first embodiment, since the inlet side openings 155a are arranged at equal intervals, the fuel in the sac chamber 154 can flow equally into the inlet side openings 155a. Therefore, in combination with the above-described configuration in which the areas A_i and A_e of the inlet side openings 155a_i and 155a_e are made uniform, the amount of fuel injected from each injection hole 155 can be made more uniform. Therefore, the homogeneity of the air-fuel mixture at various locations in the combustion chamber 90 can be further improved.

  In addition, in the first embodiment, the corner radius of the edge portion 164 on the inlet side is set to 10 micrometers or less. As shown in FIG. 10, as the corner radius of the edge portion 164 decreases, the particle size of the spray decreases. Therefore, by making the angle R of the edge portion 164 minute by using laser processing, the fuel spray injected from each injection hole 155 becomes more easily mixed with air.

  In the first embodiment, the bottom wall 160 corresponds to an “injection hole wall” recited in the claims.

(Second embodiment)
The second embodiment of the present invention shown in FIGS. 11 to 13 is a modification of the first embodiment. The fuel injection valve 210 according to the second embodiment is different from the fuel injection valve 10 according to the first embodiment (see FIG. 1) in the installation position and the installation attitude relative to the combustion chamber 90. As shown in FIGS. 11 and 12, the fuel injection valve 210 is disposed on the opposite side of the two exhaust valves 92 with the spark plug 91 interposed therebetween. The fuel injection valve 210 has a tip portion where a plurality of injection holes 255 are formed positioned between the two intake valves 93. The fuel injection valve 210 is disposed on the outer peripheral side of the combustion chamber 90 in a posture inclined with respect to the ignition plug 91, and injects fuel from the side toward the combustion chamber 90.

  The bottom wall 260 shown in FIG. 13 forms six injection holes 255 having different injection directions of the injection hole axis 259. The plurality of injection holes 255 include an intermediate injection hole 258 in addition to the exhaust-side injection hole 156 and the intake-side injection hole 157. Two exhaust side injection holes 156, two intake side injection holes 157, and two intermediate injection holes 258 are formed. The entrance-side openings 255a of the nozzle holes 156, 157, and 258 are arranged at equal intervals on the same virtual circle 19 defined around the central axis 18. In addition, the areas A_e, A_i, and A_m of the respective inlet side openings 255a are aligned with each other.

  Here, in the following description, a virtual plane including the injection hole axis 259c and the central axis 18 of the two intermediate injection holes 258 is defined as a boundary surface BP that separates the intake side and the exhaust side of the combustion chamber 90 (see FIG. 11). To do. In a state in which the fuel injection valve 210 is mounted on the gasoline engine, the boundary surface BP has an oblique posture with respect to the combustion chamber 90 as shown in FIG.

  The injection hole axis 259a of the exhaust side injection hole 156 shown in FIGS. 11 and 13 is defined to pass through a space in the combustion chamber 90 that is closer to the exhaust valve 92 than the boundary surface BP. As a result, the exhaust side injection hole 156 is directed to the exhaust side of the combustion chamber 90. The exhaust side injection hole 156 injects the fuel spray whose penetration force is suppressed toward the exhaust side space of the combustion chamber 90.

  The injection hole axis 259b of the intake side injection hole 157 is defined to pass through a space in the combustion chamber 90 that is farther from the exhaust valve 92 than the boundary surface BP. Thereby, the intake side injection hole 157 is directed to the intake side of the combustion chamber 90. The intake-side injection hole 157 supplies fuel to the intake-side space of the combustion chamber 90 by injecting fuel spray with sufficient penetration force toward the top surface of the piston 94.

  The nozzle hole axis 259c of the intermediate nozzle hole 258 shown in FIG. 13 overlaps the boundary surface BP as described above. The intermediate injection hole 258 is a straight injection hole having a substantially constant flow path area, similar to the intake-side injection hole 157. The intermediate injection hole 258 supplies fuel to the central region of the combustion chamber 90 (see FIG. 11) by injection of fuel spray with a sufficient penetrating force.

  Also in the second embodiment described above, the penetration force of the fuel spray injected from each of the injection holes 157 and 156 is individually adjusted by forming the intake side injection hole 157 and the exhaust side injection hole 156 in different shapes. ing. Therefore, as in the first embodiment, the effect of supplying an appropriate amount of fuel to various locations in the combustion chamber 90 in a state where it can be easily mixed with air can be exhibited. Therefore, also in the second embodiment, the homogeneity of the air-fuel mixture in the combustion chamber 90 is improved.

  In the second embodiment, the bottom wall 260 corresponds to an “injection hole wall” recited in the claims.

(Other embodiments)
Although a plurality of embodiments according to the present invention have been described above, the present invention is not construed as being limited to the above embodiments, and can be applied to various embodiments and combinations without departing from the gist of the present invention. can do.

  In the first embodiment, the fuel injection valve 10 is disposed so as to be surrounded by the spark plug 91 and the two intake valves 93 and injects fuel from the center of the combustion chamber 90 on the ceiling surface side. However, the relative positional relationship between such a center injection type fuel injection valve and the spark plug 91, the exhaust valve 92, and the intake valve 93 is such that the following modifications 1 to 6 of the first embodiment are used. It can be changed as appropriate.

  In the first modification shown in FIG. 14, the spark plug 91 is disposed at the center of a region surrounded by the two intake valves 93 and the two exhaust valves 92. The fuel injection valve 310 of the first modification is attached at a position shifted from the center ignition plug 91 toward the exhaust valve 92, and is disposed so as to be surrounded by the ignition plug 91 and the two exhaust valves 92. In the second modification shown in FIG. 15, the fuel injection valve 410 is disposed at the center of the region surrounded by the two intake valves 93 and the two exhaust valves 92. The spark plug 91 is attached at a position shifted from the central fuel injection valve 410 to the exhaust valve 92 side.

  In the third modification shown in FIG. 16 and the fourth modification shown in FIG. 17, the fuel injection valves 510 and 610 and the spark plug 91 are arranged in the direction in which the same type of valves are arranged, that is, the axial direction of the crankshaft (not shown) of the gasoline engine. It is arranged along. In the modification 3 and the modification 4, the fuel injection valves 510 and 610 have the above-described crankshaft configuration with respect to the spark plug 91 disposed in the center of the region surrounded by the two intake valves 93 and the two exhaust valves 92. It is attached at a position shifted along the axial direction.

  In Modification 5 shown in FIG. 18 and Modification 6 shown in FIG. 19, one intake valve 93 and one exhaust valve 92 are provided for each combustion chamber 90. The present invention can also be applied to a fuel injection valve attached to such a combustion chamber 90. Specifically, in Modification 5 shown in FIG. 18, a spark plug 91 is disposed between the intake valve 93 and the exhaust valve 92. The fuel injection valve 710 is attached to the center spark plug 91 at a position displaced along the axial direction of the crankshaft. On the other hand, in Modification 6 shown in FIG. 19, a fuel injection valve 810 is attached between the intake valve 93 and the exhaust valve 92. The spark plug 91 is attached to a position shifted from the central fuel injection valve 810 along the axial direction of the crankshaft.

  In yet another modification, the center positions of the intake valves and the exhaust valves provided one by one are shifted from each other along the axial direction of the crankshaft. In such a configuration, the spark plug is disposed in a space generated by shifting the exhaust valve. On the other hand, the fuel injection valve is disposed in a space generated by shifting the intake valve.

  In the second embodiment, the intermediate injection hole is formed in the same straight shape as the intake side injection hole. However, the intermediate nozzle hole can have an enlarged tapered shape similar to the exhaust nozzle hole. In such a form, the taper angle and L / D value of the intermediate nozzle hole may be the same as or different from those of the exhaust side nozzle hole.

  In the above embodiment, the plurality of intake side injection holes have substantially the same shape. Similarly, the plurality of exhaust side injection holes have substantially the same shape. However, each of the plurality of intake-side nozzle holes and exhaust-side nozzle holes can be formed in different shapes. The plurality of nozzle holes directed toward the intake side may include a tapered nozzle hole, a straight nozzle hole having an L / D value of less than 1.5, and the like. Similarly, a plurality of jets directed to the exhaust side include straight nozzle holes, enlarged taper nozzle holes outside the range of 2.0 to 3.0 per L / D value, and the like. May be. Further, the cross section orthogonal to each nozzle hole axis in each intake side nozzle hole and each exhaust side nozzle hole is not limited to the circular shape as in the above-described embodiment, but in an elliptical shape, a rectangular shape, a polygonal shape, or the like. It can be changed as appropriate.

  In the above embodiment, the difference in flow path length between the intake-side injection hole and the exhaust-side injection hole is adjusted by changing the wall thickness of the bottom wall in each region. Such a difference in wall thickness at each part of the bottom wall may be provided at the time of molding the nozzle body, or may be provided by cutting the tip of the nozzle body once formed. Furthermore, according to the crossing angle between the tapered surface portion and the nozzle hole axis, the wall thickness in the direction along the nozzle hole axis is apparently increased by extending the nozzle hole in an oblique direction in the bottom wall. Can do.

  In the said embodiment, the area of all the entrance side openings was made substantially the same. However, the areas of the inlet openings may be slightly different from each other. Furthermore, each center of each inlet side opening may be slightly shifted from the same virtual circle to the inner peripheral side or the outer peripheral side. Moreover, the space | interval between each inlet side opening does not need to be substantially constant. Each inlet-side opening may be appropriately shifted in the circumferential direction of the same virtual circle in accordance with the fuel flow mode in the sac chamber.

  In the above-described embodiment, the corner radius is miniaturized for each edge portion on the inlet side and the outlet side by adopting laser processing. However, the method of drilling the nozzle hole in the bottom wall is not limited to laser processing. Each nozzle hole can be formed by, for example, machining or electric discharge machining, or a combination of these machining methods.

  In the above embodiment, an example in which the present invention is applied to a fuel injection valve that injects gasoline as fuel into a combustion chamber has been described. However, the present invention is a fuel that injects fuel different from gasoline, such as gas fuel and light oil. The present invention can also be applied to an injection valve.

Dn_e, Dn_i Reference inner diameter, Ln_e, Ln_i Flow path length, A_e, A_i, A_m Open side opening area 10, 210 Fuel injection valve, 18 Central axis, 90 Combustion chamber, 152 Suck part, 153 Recess, 154 Sack Chamber, 155, 255 nozzle hole, 155a, 155a_e, 155a_i, 255a inlet side opening, 155b, 155b_e, 155b_i outlet side opening, 156 exhaust side nozzle hole, 157 intake side nozzle hole, 156a, 157a inner peripheral wall surface, 159, 159a , 159b, 259, 259a, 259b, 259c injection hole axis, 160, 260 bottom wall (hole wall), 166 second region, 167 first region, 164 edge portion

Claims (4)

A fuel injection valve that injects fuel from a plurality of injection holes (155, 255) into a combustion chamber (90) provided in an internal combustion engine,
With respect to the plurality of nozzle holes, the nozzle hole axes (159, 259) that define individual directing directions are directed in different directions,
Among the plurality of injection holes, at least one intake-side injection hole (157) directed toward the intake side of the combustion chamber according to the attitude of the injection hole axis (159b, 259b) has a reference inner diameter (Dn_i) serving as a reference. Is a straight shape that extends the inner peripheral wall surface (157a) along the nozzle hole axis line,
Among the plurality of nozzle holes, at least one exhaust side nozzle hole (156) directed toward the exhaust side of the combustion chamber according to the attitude of the nozzle hole axis (159a, 259a) is an outlet side exposed to the combustion chamber. An enlarged taper that increases the flow area from the reference inner diameter (Dn_e) toward the opening on the outlet side by separating the inner peripheral wall surface (156a) from the nozzle hole axis toward the opening (155b_e). Shape,
A sac portion (152) forming a sac chamber (154) communicating with the plurality of nozzle holes;
A nozzle hole wall (160, 260) that forms a first region (167) that penetrates the intake side nozzle hole and a second region (166) that penetrates the exhaust side nozzle hole,
Openings (155a, 255a) on the respective inlet sides of the respective nozzle holes face the sac chambers at equal intervals,
The wall thickness of the first region and the wall thickness of the second region are defined so as to correspond to the flow path length of the intake side nozzle hole and the flow path length of the exhaust side nozzle hole, respectively. Differently
The fuel injection valve according to claim 1, wherein a wall thickness of the first region is thinner than a wall thickness of the second region. The value obtained by dividing the flow path length (Ln_i) of the intake side nozzle hole by the reference inner diameter of the intake side nozzle hole is 1.5 or more,
The value obtained by dividing the flow path length (Ln_e) of the exhaust side nozzle hole by the reference inner diameter of the exhaust side nozzle hole is in the range of 2.0 to 3.0. The fuel injection valve as described.   For each of the intake-side and exhaust-side nozzle holes, the corner radii of the edge portions (164) that define the inlet-side openings (155a, 255a) are the same in each longitudinal section including the nozzle axis. The fuel injection valve according to claim 1, wherein the fuel injection valve is 10 micrometers or less.   The area (A_i) of the inlet side opening (155a_i) in the intake side nozzle hole is aligned with the area (A_e) of the inlet side opening (155a_e) in the exhaust side nozzle hole. 4. The fuel injection valve according to any one of 3.

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