JP2013050066A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve which can individually set the flow rate at every fuel injection with high precision even if using a plurality of injection holes that have the same shapes in cross sections, and in which the fluctuations of fuel injection amounts are small in the whole of the fuel injection valve.SOLUTION: The fuel injection valve includes: a plurality of fuel injection holes 21, 22; a valve seat 17a disposed at the upstream side of the fuel injection holes 21, 22; a valve body 12 which is attached to and detached from a valve seat 17a; an energizing means 10 which energizes the valve body 12 in the reverse direction to the driving direction thereof; a guide which guides the valve body 12 in the driving direction thereof; and a core 6 which regulates the amount of displacement in the driving direction thereof upon the driving of the valve body 12 where, when an angle formed of a collision surface 26 of the core 6 with a surface vertical to a center axis 19 of fuel injection valve is α and an angle formed of a collision surface 28 of the valve body 12 with a surface vertical to a center axis 18 of the valve body is β, the absolute value of at least any one of the angle α and the angle β is set to be a value larger than 0°.

Description

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

  2. Description of the Related Art In an internal combustion engine such as an automobile, an electromagnetic fuel injection valve that is driven by an electric signal from an engine control unit is widely used.

  This type of fuel injection valve includes a so-called port injection that is attached to the intake pipe and indirectly injects fuel into the combustion chamber, and a direct injection type that directly injects fuel into the combustion chamber. Exists.

  In the latter direct injection type, the spray shape formed by the injected fuel determines the combustion performance. Therefore, in order to obtain the desired combustion performance, it is necessary to optimize the spray shape. Here, the optimization of the spray shape can be rephrased as the spray direction and the spray length during the specified flow rate injection.

  In JP 2008-101499 A, as a fuel injection valve, a movable valve body, a drive means for driving the valve body, a valve seat to which the valve body is separated and connected, and a downstream of the valve seat are disclosed. There is disclosed a fuel injection valve that includes a plurality of provided orifices, wherein the plurality of orifices are formed in different angular directions with respect to the central axis of the nozzle.

  In Japanese Patent Application Laid-Open No. 2011-1864, a plurality of nozzle holes and a seat part provided on the upstream side of the nozzle holes are brought into contact with the seat part to be in a closed state, and separated from the seat part to be in a valve opening state. In a fuel injection valve having a valve body and a conical surface that is formed with an inlet side opening and a seat portion of an injection hole and is tapered from the upstream side toward the downstream side, the plurality of injection holes are formed with a central axis of the injection hole The cross-sectional shape perpendicular to the circle is substantially different from the perfect circle and is formed in the same shape, and the conical surface and the central axis of the injection hole are rotated by rotating the cross-section of the plurality of injection holes around the central axis of the injection hole By setting the rotation angle so that the relationship with the rotation angle rotated around is different in at least two nozzle holes, the flow rate of each nozzle hole is set individually using multiple nozzle holes with the same cross section A fuel injection valve is disclosed. With this fuel injection valve, it is possible to improve fuel consumption, exhaust performance, etc. in an internal combustion engine for automobiles, and it is possible to greatly reduce manufacturing costs.

JP 2008-101499 A JP 2011-1864 A

  It is known that the spray ejected from the fuel injection valve is ejected substantially in the axial direction in which the injection hole (also referred to as a fuel injection hole) is processed. As in the fuel injection valve described in Patent Document 1, a fuel injection valve having a plurality of injection holes (orifices) is required to increase the processing accuracy in the injection hole direction. Further, since the spray length is correlated with the flow rate ejected from each nozzle hole, it is required to control the flow rate of each nozzle hole in order to control the spray length of each nozzle hole. Further, for the purpose of optimizing the state of the air-fuel mixture, it is required to individually control the direction and flow rate of each spray.

  In the fuel injection valve described in Patent Document 1, no consideration is given to individually setting the flow rates of the plurality of nozzle holes. As a method for individually setting the flow rate of each nozzle hole, it is conceivable to change the hole diameter of the plurality of nozzle holes. In other words, the nozzle hole size that requires a large flow rate is set to a large hole diameter, and the nozzle hole size that requires only a small amount of flow is set to a small hole diameter to set the flow rate of each nozzle hole individually. Is possible.

  However, when changing the hole diameter of a plurality of nozzle holes, it is necessary to prepare a tool that matches the hole diameter of each nozzle hole as a tool for processing the nozzle holes. That is, it is necessary to prepare a plurality of tools for processing the hole diameter according to the flow rate and perform processing using a different tool for each nozzle hole. The number of man-hours required for preparing the tool is the same as the type and number of nozzle holes, and the setup time during processing and the inspection time after processing are longer than when the hole diameters of the nozzle holes are all the same. As a result, the manufacturing cost of the fuel injection valve also increases.

  Further, in order to use different tools when processing a plurality of nozzle holes, it is necessary to replace the tools or to transfer the material forming the nozzle holes to another processing apparatus. For this reason, a relative position shift may occur between the tool and the material, and the processing accuracy of the nozzle hole may be reduced.

  The fuel injection valve described in Patent Document 2 discloses a method of individually setting the flow rate of each nozzle hole using a plurality of nozzle holes having the same cross section. However, in general, the flow rate for each nozzle hole having the same cross-sectional shape is the flow in the vicinity of the valve body seat part and the valve seat sheet part when the valve is opened, the angle between the nozzle hole axis and the central axis of the fuel injection valve, the flow inside the nozzle hole, etc. In this fuel injection valve, the flow rate of each nozzle hole is individually controlled by focusing only on the vicinity of the nozzle hole provided in the valve seat, and the relative positional relationship with the valve seat of the valve body Is not considered. In order to individually set the flow rate of each nozzle hole with higher accuracy, it is necessary to define the relative positional relationship of the valve body with respect to the valve seat when the valve is opened. Also, defining the relative position of the valve body with respect to the valve seat is effective for reducing the variation in flow rate.

  The object of the present invention is to define the relative position of the valve body with respect to the valve seat when the fuel injection valve is driven, so that even when a plurality of fuel injection holes having the same cross section are used, It is an object of the present invention to provide a fuel injection valve in which the flow rate of each of the fuel injection valves can be individually set with high accuracy and the fuel injection amount variation of the entire fuel injection valve is small.

  In order to achieve the above goal, the fuel injection valve of the present invention closes the fuel passage by contacting a plurality of fuel injection holes, a valve seat provided on the upstream side of the fuel injection holes, and the valve seat. A valve body that opens a fuel passage by moving away from the valve seat; an urging means that urges the valve body in a direction opposite to a driving direction thereof; and a central axis of the fuel injection valve when the valve body is driven. A fuel injection valve comprising a guide for restricting a displacement in a vertical direction and a core for restricting a displacement amount in a drive direction when the valve body is driven, wherein a collision surface of the core with the valve body is a fuel injection valve. When the angle formed with respect to the plane perpendicular to the central axis of the valve body is α, and the angle formed with the collision surface of the valve body with the core perpendicular to the plane perpendicular to the central axis of the valve body is β, the angle α And the absolute value of at least one of angle β is set to a value larger than 0 degree That.

  According to the present invention, even when a plurality of fuel injection holes having the same cross section are used, the flow rate of each fuel injection hole is individually set with high accuracy and the fuel injection amount variation of the entire fuel injection valve is varied. It is possible to provide a small fuel injection valve.

Sectional drawing which shows the outline of an electromagnetic fuel injection valve. The cross-sectional enlarged view which shows the valve body and fuel injection hole vicinity of an electromagnetic fuel injection valve. The cross-sectional enlarged view of a core and a valve body when each collision surface of the core and valve body of an electromagnetic fuel injection valve which concerns on this invention is made into a taper shape. Sectional drawing which shows the contact relationship of each collision surface of a core and a valve body, and the contact relationship of a valve body and its guide member in the electromagnetic fuel injection valve which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a sectional view of an electromagnetic fuel injection valve according to the present invention. The portions of the O-ring 3 and the backup ring 4 on the upper side of FIG. 1 are inserted into the fuel pipe, and pressurized fuel is supplied into the fuel injection valve through a filter 5 having a function of preventing foreign matter from entering. On the other hand, in the fuel injection valve that directly injects fuel into the combustion chamber, the tip of the nozzle 14 is assembled to the engine head. At this time, the combustion gas is sealed by the tip seal 15. In addition, the fuel injection is controlled by opening and closing the fuel injection holes 21 and 22 formed in the valve seat member 17 attached to the tips of the valve body 12 and the nozzle 14. When the valve is closed, the valve body 12 is controlled. A spring 10 as an urging member is provided so that is pressed against a valve seat 17a formed on the valve seat member 17 to close the valve. The valve seat member 17 has a conical surface that tapers from the upstream side toward the downstream side, and the valve seat 17a is provided on the conical surface. The set load of the spring 10 when the valve is closed is adjusted by the push-in depth of the adjuster pin 7. Further, the valve body 12 is driven stably by being guided by the upper guide 13 and the lower guide 16. As a means for generating the driving force of the valve body 12, the fuel injection valve is provided with a solenoid coil 9. When the connector 1 is connected, a voltage is applied to the terminal 2 and the solenoid coil 9 is energized, the core 6, the yoke 11 and the housing 8, and the valve body 12 which are housing parts of the solenoid coil 9 are used as magnetic paths. And a suction force is generated between the core 6 and the valve body 12. When the suction force reaches a magnitude that overcomes the sum of the set load by the spring 10 and the fuel pressure by the pressurized fuel, the valve body 12 is displaced in the direction away from the valve seat 17a (upper side in FIG. 1), and the fuel Is injected. The core 6 also serves as a stopper that regulates the amount of displacement when the valve body 12 is driven.

  2 (a) to 2 (d) are enlarged sectional views of the vicinity of the valve seat 17a and the valve body 12 of the fuel injection valve. FIG. 2A shows a closed state in which the fuel injection valve is not driven, and includes a contact portion between the valve body 12 provided on the upstream side of the fuel injection holes 21 and 22 and the valve seat 17a. The seat 23 seals the fuel. Although two fuel injection holes are illustrated in FIG. 2, the number of fuel injection holes is not limited to two and may be three or more. 2 (b) to 2 (d) show the valve opening time when the fuel injection valve is in a driving state, and pass through the gap between the valve body 12 and the valve seat 17a caused by the displacement of the valve body 12, Fuel is injected from each fuel injection hole 21, 22. The individual flow rates of the fuel injection holes 21 and 22 at this time are the gap flow between the valve body 12 and the valve seat 17a in the vicinity of the fuel injection holes 21 and 22, the fuel injection hole shaft 20 and the fuel injection valve central shaft 19 respectively. And the state of the flow inside the fuel injection holes 21, 22. FIG. 2B shows a state in which the valve body central shaft 18 and the fuel injection valve central shaft 19 are completely coaxially opened. In an actual fuel injection valve, as shown in FIG. It is difficult for the valve body central shaft 18 and the fuel injection valve central shaft 19 to be completely coaxial, so that the valve body 12 is not supported by the upper guide 13 or the lower guide 16 and maintained in the open state. Due to the side force of the spring 10 urging the valve 12 and various dimensional variations, the valve body central shaft 18 at the time of valve opening is always connected to the fuel injection valve central shaft 19 as shown in FIGS. 2 (c) and 2 (d). On the other hand, an axial deviation of an amount corresponding to the clearance between the upper guide 13 or the lower guide 16 and the valve body 12 occurs. Here, in FIG. 2 (c) and FIG. 2 (d), the distribution of the flow rate for each fuel injection hole 21, 22 is different. For example, in FIG. 2 (c), the fuel flowing into the left fuel injection hole 21 The fuel flow path 25 flowing into the right fuel injection hole 22 is narrowed with respect to the flow path 24, and the flow rate increases because the flow coefficient of the left flow path 24 is larger. On the other hand, in FIG. 2D, the fuel flow path 24 flowing into the left fuel injection hole 21 is narrower than the fuel flow path 25 flowing into the right fuel injection hole 22, and the right flow path No. 25 has a larger flow rate, so the flow rate increases. Further, when the valve body central shaft 18 is displaced due to the side force of the spring 10 or the like, the displacement in the direction perpendicular to the fuel injection valve central shaft 19 depends on two points: the inner diameter of the upper guide 13 and the inner diameter of the lower guide 16. The displacement in the direction of the central axis 19 of the fuel injection valve is supported by the core 6, and the valve body 12 is off-axis with three-point support. At this time, the amount of axial deviation of the valve body central shaft 18 relative to the fuel injection valve central shaft 19 depends on the clearance amounts of the outer diameter of the valve body 12, the inner diameter of the upper guide 13 and the inner diameter of the lower guide 16, and the clearance amount increases. Accordingly, the amount of axial deviation of the valve body 12 also increases. Furthermore, with respect to the direction of the axis deviation, the axis is displaced without directivity. Therefore, in the conventional structure, it is not possible to control which state is shown in FIG. 2C or FIG. 2D, and the flow rate of each fuel injection hole changes in accordance with the axis deviation direction of the valve body 12. There was a problem of doing. In addition, the variation in the flow rate of each fuel injection hole is one of the major causes of the variation in the injection amount of the entire fuel injection valve.

  In the present embodiment, in order to solve the above-described problem, the collision surfaces of the core 6 and the valve body 12 are tapered, so that the position of the valve body 12 at the time of opening the valve body 12 and the core 6 is tapered. It can be controlled according to the angle.

  FIG. 3 shows the shapes of the core 6 and the valve body 12 of the fuel injection valve according to the present invention. FIG. 3A shows the shape of the core 6, and the taper shape in which the collision surface 26 of the core 6 with the valve body 12 has an inclination angle α with respect to the surface 27 a perpendicular to the central axis 19 of the fuel injection valve. It is said. On the other hand, FIG. 3B shows the shape of the valve body 12 so that the collision surface 28 of the valve body 12 with the core 6 has an inclination angle β with respect to the surface 27 b perpendicular to the valve body central axis 18. It is made into a taper shape.

  FIG. 4 shows the case where the core 6 shown in FIG. 3 (a) and the valve body 12 shown in FIG. 3 (b) according to the present invention are used. 28, and the contact relationship between the valve body 12 and the upper guide 13 and the lower guide 16 which are guide members thereof.

  4A shows a case where the clearance between the outer diameter of the valve body 12 and the inner diameters of the upper guide 13 and the lower guide 16 is large. When the valve body 12 is opened, the valve body 12 is moved to the core 6 by a magnetic attractive force. And collides with the collision surface 26 of the core 6 and the collision surface 28 of the valve body 12, and the valve is opened. At this time, since the clearance between the outer diameter of the valve body 12 and the inner diameters of the upper guide 13 and the lower guide 16 is large, the valve body 12 is not in contact with both guides and is held only by the collision surface 26 of the core 6. Therefore, the valve body 12 includes the angle α between the collision surface 26 of the core 6 with the valve body 12 and the surface 27a perpendicular to the fuel injection valve central axis 19, and the collision surface 28 of the valve body 12 with the core 6 and the valve body. The relative angle difference α−β with respect to the angle β with respect to the surface 27b perpendicular to the central axis 18 is tilted and held, and by setting α and β, the eccentric direction and the eccentricity of the valve body 12 when the valve is opened. It is possible to control the amount.

  On the other hand, FIG. 4B shows a case where the clearance between the outer diameter of the valve body 12 and the inner diameters of the upper guide 13 and the lower guide 16 is small. At this time, since the clearance is small, the valve body 12 is supported by the valve body support portion 30 of the upper guide 13 or the valve body support portion 31 of the lower guide 16 before the valve body 12 is inclined by the taper angle difference α−β of each collision surface. Therefore, it cannot tilt by α-β. If the amount of inclination at this time is γ, γ is smaller than α-β, but the direction in which the valve body 12 is decentered from the relative angle difference α-β between α and β is determined from the outer diameter of the valve body 12 and the upper guide 13. Further, the amount of eccentricity of the valve body 12 can be controlled by the amount of clearance with each inner diameter of the lower guide 16.

  4A and 4B, since the tapered surfaces of the valve body 12 and the core 6 are set so that α-β is positive, the valve body central axis 18 is the fuel injection valve central axis 19. Is tilted counterclockwise. At this time, the fuel flow path 25 flowing into the right fuel injection hole 22 is narrowed with respect to the fuel flow path 24 flowing into the left fuel injection hole 21, and the left flow path 24 has a flow coefficient. Increases the flow rate.

  Therefore, when it is desired to increase the flow rate of the right fuel injection hole 22, the tapered surfaces of the valve body 12 and the core 6 may be set so that α−β becomes negative. At this time, the valve body central shaft 18 is tilted clockwise with respect to the fuel injection valve central shaft 19, so that the fuel on the left side with respect to the fuel flow path 25 flowing into the fuel injection hole 22 on the right side. The fuel flow path 24 flowing into the injection hole 21 will be throttled, and the right flow path 25 has a larger flow rate coefficient, resulting in a higher flow rate.

  That is, in FIGS. 4A and 4B, the valve body 12 and the valve seat 17a are in contact with each other when the collision surface 28 of the valve body 12 and the collision surface 26 of the core 6 are in contact with each other when the valve is opened. The size of the gap generated in the sheet portion 23 changes in the circumferential direction.

  In either case of FIG. 4 (a) and FIG. 4 (b), it is possible to control the eccentric direction of the valve body 12 at the time of valve opening by making the collision surface of the valve body 12 or the core 6 into a tapered shape. In addition, the amount of eccentricity can be controlled by setting the clearance between the valve body 12 and the upper guide 13 and the lower guide 16. As a result, it is possible to reduce the fuel injection valve solid variation at the position of the valve body 12 at the time of valve opening, or the flow rate variation for each fuel injection hole caused by the injection-to-injection variation. The fuel injection amount variation can be reduced.

  FIGS. 3 and 4 show an embodiment in which the collision surface 26 of the core 6 with the valve body 12 and the collision surface 28 of the valve body 12 with the core 6 are tapered, but the position of the valve body 12 is controlled. For this purpose, it is not necessary to use a tapered shape, and it is considered effective to use a curved surface shape having directivity such as an R shape. Further, both the collision surface 26 of the core 6 with the valve body 12 and the collision surface 28 of the valve body 12 with the core 6 may not be tapered, and either one may be tapered. When either one is tapered, the control range is narrower than when both are tapered.

  Further, when the valve is closed, in order to keep the surface pressure at the seat portion 23 uniform, consideration should be given so that the urging force of the spring 10 against the valve body 12 acts in the same direction as the central axis 19 of the fuel injection valve as much as possible. desirable. For example, by setting α to a value larger than 0 degrees and β to 0 degrees, the urging force of the spring 10 against the valve body 12 acts in the same direction as the central axis 19 of the fuel injection valve when the valve is closed, and when the valve is opened, The position of the valve body 12 can be controlled according to the taper shape of the core 6.

  Although this embodiment relates to an electromagnetic fuel injection valve that uses a magnetic attractive force as a driving force of the fuel injection valve, a piezoelectric fuel injection valve that uses a piezoelectric effect as a driving force and a magnetostrictive fuel that uses a magnetostriction phenomenon as a driving force. With respect to the injection valve, the same effect as in the present embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Connector mold 2 Terminal 3 O ring 4 Backup ring 5 Filter 6 Core 7 Adjuster pin 8 Housing 9 Solenoid coil 10 Spring 11 Yoke 12 Valve body 13 Upper guide 14 Nozzle 15 Tip seal 16 Lower guide 17 Valve seat member 17a Valve seat 18 Valve Body central shaft 19 Fuel injection valve central shaft 20 Fuel injection hole shaft 21 Left fuel injection hole 22 Right fuel injection hole 23 Seat portion 24 Left flow path 25 Right flow path 26 Core collision surface 27a Vertical to the fuel injection valve central axis Surface 27b Vertical surface 28 with respect to valve body central axis Valve body collision surface 29 Core valve body support portion 30 Upper guide valve body support portion 31 Lower guide valve body support portion

Claims (4)

A plurality of fuel injection holes, a valve seat provided upstream of the fuel injection holes, a valve body that closes the fuel passage by contacting the valve seat and opens the fuel passage by moving away from the valve seat, and An urging means for urging the valve body in a direction opposite to its driving direction; a guide for regulating displacement in a direction perpendicular to the central axis of the fuel injection valve when the valve body is driven; and driving the valve body In a fuel injection valve having a core that sometimes regulates the amount of displacement in the driving direction,
The angle formed by the collision surface of the core with the valve body with respect to the plane perpendicular to the central axis of the fuel injection valve is α, and the collision surface of the valve body with the core is perpendicular to the central axis of the valve body. A fuel injection valve characterized in that an absolute value of at least one of the angle α and the angle β is set to a value larger than 0 degree when the angle formed with respect to the surface is β. The fuel injection valve according to claim 1, wherein
A fuel injection valve characterized in that both the absolute value of the angle α and the absolute value of the angle β are set to values greater than 0 degrees. The fuel injection valve according to claim 1 or 2,
2. A fuel injection valve characterized in that an absolute value | α−β | of a relative angle difference between an angle α and an angle β is set to a value larger than 0 degrees. The fuel injection valve according to any one of claims 1 to 3,
In the state where the collision surface of the valve body and the collision surface of the core are in contact with each other when the valve is opened, the size of the gap generated in the seat portion between the valve body and the valve seat changes in the circumferential direction. The fuel injection valve characterized by the above-mentioned.