JP6554955B2 - Fuel injection valve - Google Patents

Description

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

  2. Description of the Related Art Conventionally, a fuel injection valve in which a valve member is accommodated in a valve housing whose valve seat surface is reduced in diameter toward a downstream side upstream of a fuel injection hole has been widely used. In such a fuel injection valve, when the valve member urged by the elastic member is separated from and seated on the valve seat surface, the fuel injection from the injection hole is intermittently performed by opening and closing the valve. Therefore, the seating position where the valve seat surface is seated with respect to the valve seat surface is important in stabilizing the fuel injection amount.

  For example, the valve member of the fuel injection valve disclosed in Patent Document 1 is formed with a convex curved surface in an arc shape in which the center position of curvature is defined on the longitudinal section. This convex curved surface can be seated on the valve seat surface by projecting toward the valve seat surface. Here, on the longitudinal section, the seating position where the convex curved surface is seated on the valve seat surface is uniquely determined according to the center of curvature defined by the convex curved surface. Therefore, it is possible to stabilize the amount of movement when the valve member is opened from the valve seat surface, and thus the amount of fuel injected by the valve opening.

Japanese Patent Laid-Open No. 2003-314212

  According to the fuel injection valve disclosed in Patent Document 1, the center of curvature at which the convex curved surface determines the seating position is such that the valve center line of the valve member is opposite to the seating position in the radial direction on the longitudinal section. It is defined in the position beyond. This is to increase the radius of curvature of the convex curved surface in order to reduce the rate of change of the fuel injection amount with respect to wear.

  However, the static surface pressure acting at the seating position on the valve seat surface from the convex curved surface of the valve member urged toward the valve seat surface by the elastic member decreases as the curvature radius of the convex curved surface increases. As a result, fuel leaks from between the convex curved surface and the valve seat surface regardless of the closed state where the convex curved surface is seated on the valve seat surface. Such a phenomenon occurs particularly when the fuel pressure of the fuel injected into the intake port of the internal combustion engine is relatively low, and the force pressing the valve member toward the valve seat is reduced by the fuel pressure. Remarkably appear.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection valve that suppresses fuel leakage in a valve-closed state.

  The technical means of the invention for achieving the object will be described below. The reference numerals in parentheses described in the claims and in this section disclosing the technical means of the invention indicate the correspondence with the specific means described in the embodiment described in detail later. It is not intended to limit the technical scope of the invention.

The first invention disclosed in order to solve the above-mentioned problem is
A valve housing (10) having a nozzle hole (17) for injecting fuel into the internal combustion engine (2), and a valve seat surface (16) whose diameter is reduced toward the downstream side upstream of the nozzle hole;
A valve member (40) housed in the valve housing and detachably seated coaxially with respect to the valve seat surface to open and close the fuel injection from the nozzle hole;
A fuel injection valve (1) comprising an elastic member (50) for urging the valve member toward the valve seat surface,
The valve member
A convex curved surface (440) which is formed in an arc shape with a center of curvature (Pc) defined on the longitudinal section and protrudes toward the valve seat surface;
A convex curved surface formed in an arc shape from the inner peripheral side to the outer peripheral side of the seating position as a center position of curvature that determines the seating position (Ps) where the convex curved surface is seated on the valve seat surface in the radial direction on the longitudinal section The curvature center position is defined on the seating position side from the valve center line (Lv) of the valve member ,
The valve member has an additional surface (441) formed in an arc shape having a smaller radius of curvature than the convex curved surface on the longitudinal cross section, continuously on the outer peripheral side of the convex curved surface .

  According to the first invention as described above, the center of curvature of the convex curved surface formed in an arc shape on the longitudinal cross section is more convex to the valve seat surface than the valve center line of the valve member in the radial direction on the cross section. It is defined on the seating position side of the curved surface. Thereby, the curvature radius becomes as small as possible on the convex curved surface whose curvature center position approaches the seating position side. Therefore, the static surface pressure acting on the valve seat surface at the seating position can be increased from the convex curved surface having a small radius of curvature among the valve members urged toward the valve seat surface by the elastic member. Accordingly, it is possible to suppress a situation in which fuel leakage occurs between the convex curved surface and the valve seat surface in the closed state where the convex curved surface is seated on the valve seat surface.

  According to the disclosed second invention, the nozzle hole in the first invention is characterized by injecting fuel into the intake port (2b) of the internal combustion engine.

  In such a second invention, even if the pressing force for pressing the valve member in the closed state toward the valve seat surface is reduced by the relatively low fuel pressure of the injected fuel to the intake port, the first invention has a small curvature. The static surface pressure acting on the valve seat surface from the convex surface of the radius can be increased. Therefore, it is possible to suppress fuel leakage in the closed state even under a configuration in which the fuel pressure of the injected fuel is relatively low.

It is a block diagram which shows the internal combustion engine by which the fuel injection valve by one Embodiment is mounted. It is a longitudinal cross-sectional view which shows the fuel injection valve by one Embodiment. It is a longitudinal cross-sectional view which expands and shows FIG. 2 partially. FIG. 6 is an enlarged longitudinal sectional view showing a contact portion in FIGS. 2 and 3, and is a longitudinal sectional view taken along line IV-IV in FIG. 5. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. It is a longitudinal cross-sectional view which shows the modification of FIG. It is a longitudinal cross-sectional view which shows the modification of FIG. It is a longitudinal cross-sectional view which shows the modification of FIG. It is a longitudinal cross-sectional view which shows the modification of FIG. It is a longitudinal cross-sectional view which shows the modification of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, as an embodiment of the present invention, a fuel injection valve 1 is mounted on an internal combustion engine 2 that burns gasoline in a cylinder 2a. The fuel injection valve 1 injects the fuel sucked into the cylinder 2a together with the intake air into the intake port 2b through which the intake air flows.

(Basic configuration)
First, the basic configuration of the fuel injection valve 1 will be described. As shown in FIG. 2, the fuel injection valve 1 includes a valve housing 10, a fixed core 20, a movable core 30, a valve member 40, an elastic member 50, and a drive unit 60.

  The valve housing 10 includes a pipe member 11, a valve seat member 12, a nozzle hole member 13, and the like. The cylindrical pipe member 11 has a first magnetic part 110, a nonmagnetic part 111, and a second magnetic part 112 in this order from the valve opening side to the valve closing side in the axial direction. The magnetic parts 110 and 112 made of a metal magnetic material and the nonmagnetic part 111 made of a metal nonmagnetic material are coupled coaxially by, for example, laser welding. Due to this coupling structure, the nonmagnetic portion 111 blocks a short circuit of magnetic flux between the first magnetic portion 110 and the second magnetic portion 112.

  The first magnetic part 110 forms a supply inlet 14 that receives the supply of fuel from the fuel pump 3 (see FIG. 1). A valve seat member 12 made of a cylindrical metal is coaxially fitted and fixed to the second magnetic portion 112. The valve seat member 12 forms a fuel passage 15 in cooperation with the pipe member 11 so that the fuel guided from the upstream side flows to the downstream side. At the same time, the valve seat member 12 has a valve seat surface 16 exposed to the fuel passage 15 as shown in FIGS. In the present embodiment, the valve seat surface 16 is formed in a tapered surface shape (conical surface shape) having a constant diameter reduction rate as a reduced diameter shape that decreases in diameter toward the downstream side of the fuel passage 15.

  The nozzle member 13 made of a bottomed cylindrical metal is coaxially fitted and fixed to the valve seat member 12 on the side opposite to the second magnetic portion 112. The nozzle hole member 13 has a plurality of nozzle holes 17 at the bottom. Each nozzle hole 17 communicates with the fuel passage 15 on the downstream side of the valve seat surface 16 and opens radially toward the intake port 2b (see FIG. 1).

  As shown in FIG. 2, the fixed core 20 made of a cylindrical metal magnetic body is coaxially fitted and fixed to the first magnetic part 110 and the nonmagnetic part 111. An adjusting pipe 22 made of a cylindrical metal is press-fitted and fixed coaxially to the fixed core 20. The fixed core 20 forms a fixed passage 24 together with the adjusting pipe 22 so that the fuel flowing in from the upstream supply inlet 14 flows out to the downstream side.

  The movable core 30 made of a cylindrical metal magnetic body is accommodated coaxially in the nonmagnetic portion 111 and the second magnetic portion 112. The movable core 30 can reciprocate to both sides in the axial direction on the valve closing side with respect to the fixed core 20. The valve member 40 made of a bottomed cylindrical metal nonmagnetic material is accommodated coaxially across the second magnetic portion 112 and the valve seat member 12. As shown in FIGS. 2 and 3, the valve member 40 is fitted and fixed to the movable core 30 from the valve closing side. Thereby, the valve member 40 can be reciprocated integrally with the movable core 30 to both sides in the axial direction along its own valve center line Lv. The valve member 40 forms a movable passage 42 together with the movable core 30 so as to guide the fuel flowing out from the upstream fixed passage 24 to the downstream fuel passage 15.

  The valve member 40 has a contact portion 44 that reciprocates on the upstream side of the valve seat surface 16 at the bottom portion on the valve closing side. As shown in FIGS. 2 to 4, the valve member 40 causes the contact portion 44 to be coaxially separated from and seated on the valve seat surface 16 having the reduced diameter shape on the upstream side of all the injection holes 17. Specifically, the valve member 40 moves to the valve opening side, thereby causing the contact portion 44 to be separated from the valve seat surface 16 over the entire circumference. As a result, the valve member 40 is opened, and each nozzle hole 17 communicates with the fuel passage 15. Therefore, fuel is injected from each nozzle hole 17 into the intake port 2b (see FIG. 1). On the other hand, the valve member 40 moves to the valve closing side to seat the contact portion 44 on the valve seat surface 16 over the entire circumference. As a result, the valve member 40 is closed and each injection hole 17 is disconnected from the fuel passage 15, so that fuel injection from each injection hole 17 is stopped. As described above, the valve member 40 can be opened and closed by opening and closing the valve seat surface 16 so that fuel injection from each nozzle hole 17 can be intermittently performed.

  As shown in FIG. 2, the elastic member 50 is a compression coil spring made of metal, and is accommodated coaxially in the passages 24 and 42 in the fixed core 20 and the movable core 30. The elastic member 50 is sandwiched between the adjusting pipe 22 in the fixed core 20 and the movable core 30. With this clamping structure, the elastic member 50 generates an elastic restoring force in response to compression between the elements 22 and 30, thereby attaching the movable core 30 and the valve member 40 toward the valve seat surface 16 on the valve closing side. Rush. That is, the elastic restoring force generated by the elastic member 50 becomes a biasing force that biases the movable core 30 and the valve member 40.

  The drive unit 60 includes a solenoid coil 61, a spool 62, a terminal 63, a connector 64, and the like. The solenoid coil 61 is formed by winding a metal wire around a spool 62 made of a cylindrical resin. The solenoid coil 61 is coaxially fitted and fixed to the magnetic portions 110 and 112 and the nonmagnetic portion 111 via the spool 62. A terminal 63 made of metal is embedded in a connector 64 made of resin, and electrically connects the external control circuit 4 (see FIG. 1) and the internal solenoid coil 61. With this electrical connection, the energization of the solenoid coil 61 can be controlled by the control circuit 4.

  In the valve opening operation of the fuel injection valve 1 configured as described above, the solenoid coil 61 energized by the control circuit 4 is excited to excite the first magnetic part 110, the fixed core 20, the movable core 30, and the second magnetism. The magnetic flux is guided to the portion 112. As a result, a magnetic attractive force is generated between the cores 20 and 30 facing each other so as to attract the movable core 30 toward the fixed core 20 on the valve opening side. Then, since the movable core 30 is driven together with the valve member 40 to the valve opening side against the urging force of the elastic member 50, the movable core 30 is brought into contact with and locked to the fixed core 20. At this time, the valve member 40 separates the contact portion 44 from the valve seat surface 16, so that fuel is injected from each injection hole 17.

  On the other hand, in such a valve closing operation after the valve opening operation, the solenoid coil 61 that is de-energized by the control circuit 4 is demagnetized, so that the magnetic attractive force between the cores 20 and 30 disappears. Then, since the movable core 30 is driven together with the valve member 40 to the valve closing side by the urging force of the elastic member 50, the valve member 40 contacts and is locked to the valve seat member 12. As a result, the valve member 40 causes the contact portion 44 to be seated on the valve seat surface 16, so that fuel injection from each nozzle hole 17 stops. The valve member 40 thus closed is urged toward the valve seat surface 16 by the fuel pressure acting on the contact portion 44 from the fuel in the movable passage 42 in addition to the urging force of the elastic member 50. It becomes.

(Detailed configuration of valve member)
Next, the detailed structure of the valve member 40 is demonstrated based on FIG. FIG. 4 illustrates one of longitudinal sections that are cut including a valve center line Lv assumed to extend at the radial center of the valve member 40. Therefore, in the following, an arbitrary longitudinal section including the longitudinal section of FIG. 4 regarding the valve member 40 is simply referred to as a longitudinal section.

  As shown in FIG. 4, the valve member 40 has a valve outer peripheral surface 46 that extends straight in a cylindrical shape centered on the valve center line Lv on the outer peripheral side and the valve opening side of the contact portion 44. At the same time, the valve member 40 has a convex curved surface or a flat tip surface 47 on the inner peripheral side and the valve closing side of the contact portion 44. Further, the valve member 40 has a convex curved surface 440 that protrudes in a curved surface shape toward the valve seat surface 16 of the valve seat member 12 in the valve housing 10 over the entire circumference of the contact portion 44. The convex curved surface 440 is continuous from the valve outer peripheral surface 46 to the inner peripheral side. Thereby, the convex curved surface 440 forms the bending part 48 in edge shape over the perimeter of the boundary part with the valve | bulb outer peripheral surface 46. FIG. From the convex curved surface 440, the front end surface 47 is bent and connected to the inner peripheral side. As a result, the front end surface 47 forms a flat sack chamber 150 as a part of the fuel passage 15 between the nozzle hole member 13 in the valve housing 10 and guides fuel to the nozzle holes 17 when the valve is opened. ing.

  The convex curved surface 440 is formed in a circular arc shape having a curvature center position Pc on the longitudinal section with a curvature radius Rc. The curvature center position Pc uniquely determines the seating position Ps where the convex curved surface 440 having such a circular arc shape is seated on the valve seat surface 16 having a tapered surface. Therefore, the curvature center position Pc that determines the seating position Ps that increases the surface pressure is defined at a specific position on the seating position Ps side of the valve center line Lv of the valve member 40 in the radial direction on the longitudinal section. Here, a reference midpoint Pb is assumed to be a midpoint between the valve center line Lv and the seating position Ps in the radial direction on the longitudinal section. Under such assumption, particularly in the radial direction on the vertical cross section according to the present embodiment, the midpoint Pm between the reference midpoint Pb and the seating position Ps on the side of the seating position Ps from the valve center line Lv and the reference midpoint Pb. Further, the curvature center position Pc is defined on the seating position Ps side. That is, the curvature center position Pc is defined between the midpoint Pm and the seating position Ps in the radial direction on the longitudinal section.

  Thus, the curvature center position Pc defined for each longitudinal section is located on a circumference Cc centered on the same line Lv on the transverse section of FIG. 5 substantially orthogonal to the valve center line Lv. Further, as schematically shown in FIG. 5, the seating position Ps where the convex curved surface 440 is seated on the valve seat surface 16 is centered on the valve center line Lv on the outer peripheral side of the circumference Cc of the curvature center position Pc. It will be located on the circumference Cs.

(Function and effect)
The effect of the fuel injection valve 1 demonstrated above is demonstrated below.

  According to the fuel injection valve 1, the curvature center position Pc of the convex curved surface 440 formed in an arc shape on the longitudinal section is larger than the valve center line Lv of the valve member 40 in the radial direction on the section. 16 is defined on the seating position Ps side of the convex curved surface 440. Thereby, the curvature radius Rc becomes as small as possible in the convex curved surface 440 in which the curvature center position Pc approaches the seating position Ps side. Therefore, a static surface pressure acting on the valve seat surface 16 at the seating position Ps is applied to the valve seat surface 16 from the convex curved surface 440 of the valve member 40 biased toward the valve seat surface 16 by the elastic member 50. Can be increased. Therefore, it is possible to suppress a situation in which fuel leakage occurs between the convex curved surface 440 and the valve seat surface 16 in a valve-closed state where the convex curved surface 440 is seated on the valve seat surface 16.

  Further, according to the fuel injection valve 1, the curvature center position Pc of the convex curved surface 440 in the radial direction on the longitudinal section is on the side of the seating position Ps from the reference midpoint Pb assumed between the valve center line Lv and the seating position Ps. Stipulated. Here, in particular, according to the fuel injection valve 1 of the present embodiment, the center of curvature Pc of the convex curved surface 440 in the radial direction on the longitudinal section is more than the midpoint Pm between the reference midpoint Pb and the seating position Ps. Further, it is defined on the seating position Ps side. As a result, the curvature center position Pc is closer to the seating position Ps than the valve center line Lv and the reference midpoint Pb. Therefore, the convex curved surface 440 acts on the valve seat surface 16 by reducing the curvature radius Rc. To ensure an increase in Therefore, it is possible to improve the reliability with respect to the effect of suppressing the fuel leakage in the valve closed state.

  In addition, according to the fuel injection valve 1, the convex curved surface 440 having a small radius of curvature Rc in the longitudinal section is bent from the valve outer peripheral surface 46 of the valve member 40 and connected continuously, thereby reducing the diameter of the valve seat toward the downstream side. A larger gap 151 (see FIG. 4) can be secured between the surface 16 and the outer periphery side from the seating position Ps. According to this, even if the valve member 40 is inclined with respect to the valve seat surface 16 due to the bias of the urging force by the elastic member 50, the bent portion 48 formed by the valve outer peripheral surface 46 and the convex curved surface 440 is It becomes difficult to contact the valve seat surface 16. Therefore, while avoiding the bent portion 48 from coming into contact with the valve seat surface 16 on the outer peripheral side of the normal seating position Ps, the static surface pressure is generated by the convex curved surface 440 having the small curvature radius Rc at the normal seating position Ps. It is possible to suppress fuel leakage when the valve is closed.

  In addition, in the fuel injection valve 1, even if the pressing force that presses the valve member 40 in the closed state toward the valve seat surface 16 is reduced due to the relatively low fuel pressure of the fuel injected into the intake port 2b, the small radius of curvature is reduced. The static surface pressure acting on the valve seat surface 16 from the convex curved surface 440 of Rc can be increased. Therefore, it is possible to suppress fuel leakage in the closed state even under a configuration in which the fuel pressure of the injected fuel is relatively low.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not construed as being limited to the embodiment, and can be applied to various embodiments without departing from the gist of the present invention. it can.

  Specifically, in Modification 1, as shown in FIG. 6, the curvature center position Pc of the convex curved surface 440 in the radial direction on the longitudinal section is set to the reference position on the side of the seating position Ps from the valve center line Lv and the reference midpoint Pb. You may prescribe | regulate between the midpoint Pb and the midpoint Pm. Further, in Modification 2, as shown in FIG. 7, the curvature center position Pc of the convex curved surface 440 in the radial direction on the longitudinal section is set to the valve center line Lv on the seating position Ps side with respect to the valve center line Lv. You may prescribe | regulate between the midpoints Pb.

  In Modification 3, as shown in FIG. 8, an additional surface 441 that connects the surfaces 440 and 46 is formed on the outer peripheral side of the convex curved surface 440 and the inner peripheral side of the valve outer peripheral surface 46 in the contact portion 44. May be. The additional surface 441 may be formed in a convex curved surface shape having a circular arc shape with a radius of curvature Ra smaller than that of the convex curved surface 440 as shown in FIG. May be. In FIG. 8, the boundary between the convex curved surface 440 and the additional surface 441 is indicated by reference numeral 49.

  In the fourth modification, as shown in FIG. 9, the valve seat surface 16 may be formed in a curved surface shape in which the diameter reduction rate toward the downstream side of the fuel passage 15 decreases toward the downstream side. Moreover, in the modification 5, as shown in FIG. 10, the valve seat surface 16 may be formed in a curved surface shape in which the diameter reduction rate that decreases toward the downstream side of the fuel passage 15 increases toward the downstream side. .

  In the sixth modification, the present invention may be applied to a fuel injection valve that injects fuel into a cylinder of a gasoline internal combustion engine. In Modification 7, the present invention may be applied to a fuel injection valve that injects fuel into a cylinder of a diesel internal combustion engine.

DESCRIPTION OF SYMBOLS 1 Fuel injection valve, 2 Internal combustion engine, 2b Intake port, 10 Valve housing, 16 Valve seat surface 17 Injection hole, 40 Valve member, 44 Contact part, 46 Valve outer peripheral surface, 48 Bending part, 50 Elastic member, 151 Clearance, 440 Convex surface, Lv valve center line, Pb reference midpoint, Pc curvature center position, Pm midpoint, Ps seating position, Rc curvature radius

Claims (5)

A valve housing (10) having a nozzle hole (17) for injecting fuel to the internal combustion engine (2), and a valve seat surface (16) whose diameter is reduced toward the downstream side upstream of the nozzle hole;
A valve member (40) housed in the valve housing and configured to open and close and to intermittently inject fuel from the nozzle hole by being seated coaxially with respect to the valve seat surface;
A fuel injection valve (1) comprising an elastic member (50) for urging the valve member toward the valve seat surface,
The valve member is
A convex curved surface (440) which is formed in an arc shape with a center of curvature (Pc) defined on the longitudinal section and protrudes toward the valve seat surface;
In the radial direction on the longitudinal section, the convex curved surface is formed in an arc shape extending from the inner peripheral side to the outer peripheral side of the seating position as the curvature center position that determines the seating position (Ps) on which the valve seat is seated The center of curvature of the convex curved surface is defined on the seating position side of the valve center line (Lv) of the valve member ,
The valve member has an additional surface (441) formed in an arc shape having a smaller radius of curvature than the convex curved surface on the longitudinal section, continuously on the outer peripheral side of the convex curved surface. Injection valve.   In the radial direction on the longitudinal section, the center of curvature is defined on the side of the seating position with respect to a reference midpoint (Pb) assumed as a midpoint between the valve center line and the seating position. The fuel injection valve according to claim 1.   3. The curvature center position in the radial direction on the longitudinal section is defined closer to the seating position than a midpoint (Pm) between the reference midpoint and the seating position. The fuel injection valve described in 1.   The fuel injection valve according to any one of claims 1 to 3, wherein the convex curved surface is bent from the valve outer peripheral surface (46) of the valve member.   The fuel injection valve according to any one of claims 1 to 4, wherein the injection hole injects fuel into an intake port (2b) of the internal combustion engine.

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