JP2012154309A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute to the improvement of the combustion property and the exhaust property of fuel by accelerating atomization of the injected fuel by generating whirling stream in the inside of the nozzle body with simple structure and at low cost.SOLUTION: The fuel injection nozzle 1 has the nozzle body 4 formed with an injection hole 2 for injecting fuel at one end and having a fuel passage 3 for guiding fuel to the injection hole 2, and a needle 5 which is a shaft shape member inserted into the nozzle body 4 and which constitutes a valve part 7 opening and closing the fuel passage 3 by the reciprocating moving in an axial direction to the nozzle body 4 along with the nozzle body 4, the fuel passage 3 has a fuel reservoir part 8, a fuel supply passage 21 arranged an upstream side more than the fuel reservoir part 8 and guiding fuel toward an inserting direction side to the nozzle body 4 of the needle 5, and a direction changing passage part 22 arranged between the fuel reservoir 8 and the fuel supply passage 21, and formed in a direction along a plane perpendicular to the axial direction of the needle 5, and communicating in a direction displaced from the diameter direction of the needle 5 to the fuel reservoir part 8.

Description

  The present invention relates to a fuel injection nozzle used for a diesel engine or the like.

  Conventionally, in an engine such as a diesel engine, in order to reduce emissions of toxic substances contained in exhaust gas, improve thermal efficiency that promotes reduction of carbon dioxide emissions, reduce smoke emissions, etc. Improvement of the characteristics of the fuel injection nozzle constituting the injection valve is an important key. In particular, from the viewpoint of reducing the amount of smoke discharged, it is desirable that the fuel injected from the fuel injection nozzle be quickly atomized into fuel vapor, mixed with air, and burned. Therefore, in the fuel injection nozzle, conventionally, in order to promote atomization of the injected fuel spray, various measures such as increasing the fuel injection pressure and miniaturizing the fuel injection hole have been performed.

  In the fuel injection nozzle, in order to promote atomization of the injected fuel, there is a conventional technique for generating a swirling flow in the injected fuel. As a configuration for generating a swirling flow in the fuel to be injected, for example, as in the fuel injection nozzle of Patent Document 1, the swirling flow of the fuel to be injected is an injection immediately before the fuel is ejected from the nozzle to the outside of the fuel injection nozzle. Some are generated in the hole. Specifically, the fuel injection nozzle disclosed in Patent Document 1 has a flow rate in a predetermined direction of the fuel flowing into the nozzle hole by, for example, forming a nozzle hole through which fuel is jetted in a tangential direction of the inner peripheral surface of the valve seat. A slow speed is generated, and a swirling flow is generated in the nozzle hole.

  On the other hand, as a configuration for generating a swirling flow in the fuel to be injected, for example, as in the fuel injection nozzle of Patent Document 2, the swirling flow of the fuel to be injected is a nozzle called an upstream side of the nozzle hole, that is, a nozzle body or the like Some are generated inside the body. The fuel injection nozzle of Patent Document 2 generates a swirling flow around a needle that is inserted into a nozzle body and seats on a valve seat provided in the nozzle body. For this reason, in the fuel injection nozzle of patent document 2, the spiral groove is formed in the outer peripheral surface of a needle.

Japanese Patent Laid-Open No. 11-324868 Japanese Patent Laid-Open No. 6-147057

  According to the configuration in which the spiral groove is formed on the outer peripheral surface of the needle like the fuel injection nozzle of Patent Document 2, the shape of the needle becomes complicated. For this reason, it is difficult to process the needle, and the processing cost increases.

  On the other hand, in order to promote atomization of injected fuel, a method of compressing fuel containing microbubbles with a pump has been devised. However, the method using microbubbles requires power to generate and put microbubbles into the fuel, the lifetime of microbubbles is limited, the inside of the pump for compression and the connection to the pump It is considered impractical because air bubbles are generated in the middle of the pipe and fuel cannot be sent normally.

  Therefore, the present invention can generate a swirling flow inside the nozzle body at a low cost with a simple structure, can promote atomization of the injected fuel, and improve the combustibility and exhaust characteristics of the fuel. An object of the present invention is to provide a fuel injection nozzle that can contribute to the above.

  The fuel injection nozzle according to the present invention is a nozzle body having a fuel passage for injecting fuel at one end, a fuel passage for guiding the fuel to the nozzle hole, and a shaft-like member inserted into the nozzle body, And a needle that forms a valve portion that opens and closes the fuel passage by reciprocating in the axial direction with respect to the nozzle body, and the fuel passage is arranged around an axis of the needle together with an outer peripheral surface of the needle. A fuel reservoir portion that forms a space for holding fuel; a first passage portion that is provided upstream of the fuel reservoir portion and guides fuel toward an insertion direction side of the needle with respect to the nozzle body; and the fuel The needle is provided between the reservoir and the first passage, and is formed in a direction along a plane perpendicular to the axial direction of the needle, and the radial direction of the needle with respect to the fuel reservoir A second passage portion communicating with the al displacement direction, and has a.

  In the fuel injection nozzle according to the present invention, preferably, the second passage portion constitutes a restriction for the fuel reservoir portion and the first passage portion.

  In the fuel injection nozzle of the present invention, preferably, the fuel reservoir portion has an inner peripheral surface portion that is circular when viewed in the axial direction of the needle, and the second passage portion is located with respect to the fuel reservoir portion. In this way, the circular shape communicates with the tangential direction.

  In the fuel injection nozzle of the present invention, it is preferable that the space formed by the fuel reservoir has a tapered shape that decreases in diameter toward the downstream side along the axial direction of the needle.

  According to the present invention, with a simple structure, a swirl flow can be generated inside the nozzle body at a low cost, atomization of the injected fuel can be promoted, and fuel combustibility and exhaust characteristics are improved. Can contribute.

The partial cross section figure which shows the structure of the fuel injection nozzle which concerns on one Embodiment of this invention. The partial cross section figure which shows the valve opening state of the fuel injection nozzle which relates to one execution form of this invention. Sectional drawing which shows the structure of the nozzle main body of the fuel injection nozzle which concerns on one Embodiment of this invention. The A direction arrow directional view in FIG. BB sectional drawing in FIG. The figure which shows the other structural example of the fuel-injection nozzle which concerns on one Embodiment of this invention. The figure which shows the other structural example of the fuel-injection nozzle which concerns on one Embodiment of this invention. The figure which shows the structure of the comparative example goods with respect to the Example goods which concern on the Example of this invention. The figure which shows the structure of the analyzer which concerns on the Example of this invention. The figure which shows an example of the continuous captured image showing the mode of combustion of the fuel which concerns on the Example of this invention. The figure which shows an example of the continuous captured image showing the mode of combustion of the fuel which concerns on the Example of this invention. The figure which shows an example of the continuous captured image showing the mode of combustion of the fuel which concerns on the Example of this invention. The figure which shows the time change of the atmospheric pressure in the combustion process of the fuel which concerns on the Example of this invention. Explanatory drawing about imaging | photography of the mode of the spraying of the fuel which concerns on the Example of this invention. The figure which shows the example of imaging | photography result of the mode of the spray of the fuel which concerns on the Example of this invention.

  In the nozzle body constituting the fuel injection nozzle, the structure of the fuel path formed to guide the fuel to the nozzle hole for ejecting the fuel is devised, so that the inside of the nozzle body is simplified. A swirling flow is generated to promote atomization of the injected fuel. In addition, by forming a predetermined portion as a throttle in the fuel path, the occurrence of cavitation inside the nozzle body is promoted, and atomization of the injected fuel is promoted more effectively. Embodiments of the present invention will be described below.

  The fuel injection nozzle 1 of the present embodiment is applied to, for example, marine and automobile engines, and constitutes an injection valve for fuel such as diesel fuel in the engine. That is, for example, in the engine, the fuel injection nozzle 1 is provided so as to inject fuel into a combustion chamber that forms a fuel combustion space in a cylinder.

  The fuel injection nozzle 1 receives a supply of fuel sent from a fuel tank or the like under pressure by a compressor, a fuel pump, or the like, and injects the fuel into the combustion space of the engine. For this reason, as shown in FIG. 1, the fuel injection nozzle 1 includes a nozzle hole 2 through which fuel is ejected and a fuel passage 3 that is a fuel path for guiding the supplied fuel to the nozzle hole 2.

  In other words, the fuel injection nozzle 1 is provided in the engine in such a posture that the injection hole 2 faces the combustion space, and the fuel supplied in a state of being pressurized by a fuel pump or the like is supplied to the injection hole 2 by the fuel passage 3. The fuel is injected into the combustion space by being guided and ejected from the nozzle hole 2. In the following description, in the fuel injection nozzle 1, the side where the nozzle hole 2 is provided (the lower side in FIG. 1) is the lower side, and the opposite side (the upper side in FIG. 1) is the upper side.

  The fuel injection valve constituted by the fuel injection nozzle 1 constitutes, for example, a common rail fuel injection system. The common rail type fuel injection system is a system that includes a plurality of fuel injection valves and a common rail that stores high-pressure fuel, and uniformly supplies fuel from the common rail to each fuel injection valve.

  In the common rail fuel injection system, the fuel injection pressure, injection timing, injection amount, and the like are electronically controlled by a control device. For this reason, when the fuel injection nozzle 1 constitutes each fuel injection valve of the common rail fuel injection system, the fuel injection nozzle 1 is electronically controlled by the control device with respect to its operation and the like.

  As shown in FIGS. 1 to 5, the fuel injection nozzle 1 of this embodiment includes a nozzle body 4 and a needle 5. The nozzle body 4 is a member having a substantially cylindrical outer shape as a whole. The needle 5 is an axial member having a substantially cylindrical outer shape as a whole. 3 corresponds to a cross-sectional view taken along the line CC in FIG.

  The needle 5 is provided so as to be relatively movable in the axial direction (vertical direction) in a state of being inserted at a position that is substantially coaxial with the nozzle body 4. In other words, the needle 5 is inserted into the nozzle body 4 in a state where movement in the insertion / removal direction (vertical direction) with respect to the nozzle body 4 is allowed.

  As shown in FIGS. 1 to 5, the nozzle body 4 has a guide surface 6 that forms a hole into which the needle 5 is inserted. The nozzle body 4 accommodates the needle 5 in a state in which the needle 5 can slide back and forth in the axial direction (vertical direction). For this reason, the guide surface 6 that forms the insertion hole of the needle 5 is formed as an inner peripheral surface corresponding to the outer peripheral surface of the needle 5 so that the needle 5 inserted into the nozzle body 4 slides. That is, the outer diameter dimension of the portion that slides with respect to the guide surface 6 of the needle 5 and the inner diameter dimension of the guide surface 6 are substantially the same. The guide surface 6 guides the movement of the needle 5 in the axial direction and holds the needle 5 in the nozzle body 4.

  As shown in FIG. 1, the fuel injection nozzle 1 includes a valve body 7 that opens and closes the fuel passage 3 by a nozzle body 4 and a needle 5. The valve unit 7 opens and closes by reciprocating sliding of the needle 5 with respect to the nozzle body 4. Specifically, it is as follows.

  The nozzle hole 2 of the fuel injection nozzle 1 is formed at the lower end of the nozzle body 4. The fuel injection nozzle 1 of this embodiment has one injection hole 2. The nozzle hole 2 is located on the axial center line of the needle 5 and penetrates along the axial direction of the needle 5. The nozzle hole 2 opens the fuel passage 3 to the outside of the nozzle body 4 below the nozzle body 4.

  Further, the fuel passage 3 opens in the end surface 4a on the opposite side (upper side) of the nozzle body 4 to the side where the nozzle holes 2 are formed. An opening with respect to the end face 4 a of the fuel passage 3 becomes an inlet portion 3 a of the fuel passage 3. Accordingly, the fuel supplied to the fuel injection nozzle 1 flows from the inlet 3 a and is guided to the injection hole 2 by the fuel passage 3.

  A fuel reservoir 8 is provided between the nozzle hole 2 and the guide surface 6. The fuel reservoir 8 constitutes a part of the fuel passage 3. The fuel reservoir 8 forms a space 18 by the inner peripheral surface 9. The space 18 formed by the inner peripheral surface 9 has a portion whose diameter is increased with respect to the insertion hole of the needle 5 so as to open the lower end side of the insertion hole of the needle 5 formed by the guide surface 6. The fuel reservoir 8 communicates with the nozzle hole 2 via the tip passage portion 10. That is, the tip passage portion 10 is provided between the fuel reservoir portion 8 and the nozzle hole 2. The distal end passage portion 10 is provided to ensure the strength of the nozzle body 4 in the valve portion 7, but the passage length is preferably shorter.

  The distal end passage portion 10 is a portion that forms a substantially cylindrical space coaxially with the needle 5. The tip passage portion 10 forms a space whose diameter is enlarged with respect to the injection hole 2, and the fuel reservoir portion 8. Forms a reduced diameter space. That is, the radial dimension of the tip passage portion 10 is larger than the radial dimension of the nozzle hole 2 and smaller than the radial dimension of the fuel reservoir 8.

  Therefore, the upper end side (the side opposite to the side communicating with the injection hole 2) of the tip passage portion 10 opens with respect to the fuel reservoir portion 8. The opening of the tip passage portion 10 with respect to the fuel pool portion 8 is closed by the needle 5 so that the valve portion 7 is closed.

  Since the distal end passage portion 10 is closed by the needle 5, a valve seat 11 is provided on a portion of the inner peripheral surface 9 forming the fuel reservoir portion 8 on the distal end passage portion 10 side. The valve seat 11 is formed in a peripheral portion of the opening portion of the tip passage portion 10 with respect to the fuel reservoir portion 8.

  The valve seat 11 forms a seat surface which is a truncated cone-shaped inner peripheral surface that is reduced in diameter toward the lower side (the nozzle hole 2 side). Therefore, the valve seat 11 communicates with the nozzle hole 2 on the small diameter side and communicates with the fuel reservoir 8 on the large diameter side. The valve seat 11 is provided such that the axial center direction of the frustoconical seat surface coincides with the axial center direction of the needle 5.

  The tip of the needle 5 that functions as a valve body is seated on the valve seat 11 that constitutes the valve portion 7. The needle 5 has a reduced diameter portion 12 at the end on the distal end side in the insertion direction with respect to the nozzle body 4. The reduced diameter portion 12 is a portion having a small diameter with respect to the portion forming the guide surface 6 in the needle 5. The reduced diameter portion 12 is located in the fuel reservoir 8. On the further distal end side of the reduced diameter portion 12, a seat portion 13 that is a portion seated on the valve seat 11 is provided.

  The seating portion 13 has a conical shape that decreases in diameter toward the distal end side of the needle 5. The outer peripheral surface of the seating portion 13 becomes a seating surface with respect to the seating surface formed by the valve seat 11. That is, when the seating surface formed by the seating portion 13 comes into contact with the seating surface formed by the valve seat 11, the valve portion 7 is closed, and the seating surface formed by the seating portion 13 becomes the valve seat. The valve part 7 is in an open state by being separated from the seating surface formed by 11.

  FIG. 1 shows a closed state of the fuel injection nozzle 1, that is, a state where the valve portion 7 is closed, and FIG. 2 shows a opened state of the fuel injection nozzle 1, that is, a state where the valve portion 7 is opened. The valve part 7 opens and closes by reciprocating sliding of the needle 5 as described above. The needle 5 is provided in a state in which it is urged downward by a biasing member such as a spring in a direction in which the valve portion 7 is closed, that is, downward. Since the needle 5 receives the urging force of the urging member, the needle 5 has a protruding portion 14 at the end opposite to the seating portion 13 (upper side). The protruding portion 14 is formed as a columnar protruding portion having a small diameter with respect to the portion forming the guide surface 6 at the upper end portion of the needle 5.

  On the other hand, the needle 5 has a tapered surface 12 a that is reduced in diameter toward the distal end side (lower side) in the reduced diameter portion 12. As described above, the reduced diameter portion 12 is located in the fuel reservoir 8, and the fuel reservoir 8 constitutes a part of the fuel passage 3. Therefore, the needle 5 opens the valve portion 7 by receiving the pressure of the fuel maintained at a high pressure (for example, 800 atm) supplied to the fuel passage 3 by the tapered surface 12a in the fuel reservoir portion 8. Subject to direction (upward) force.

  When the fuel injection nozzle 1 is applied to a common rail fuel injection system as described above, the operation of the needle 5 of the fuel injection nozzle 1 is performed by a known configuration including an electromagnetic valve, a piezoelectric element (piezoelectric element), and the like. Electronically controlled. The needle 5 receives an action of a force in the direction of opening the valve portion 7 (upward) or a force in the direction of closing the valve portion 7 (downward) by electronic control.

  In any case, the opening / closing operation of the valve unit 7 is performed by the change in the magnitude relationship of the vertical force acting on the needle 5. That is, when the downward force received by the needle 5 due to the biasing force or the like by the biasing member is larger than the upward force received by the needle 5 by the tapered surface 12a or the like in the fuel reservoir 8, the seating portion 13 at the tip of the needle 5 is used. Is seated on the valve seat 11 and the valve portion 7 is closed (see FIG. 1). On the other hand, when the upward force received by the needle 5 is larger than the downward force, the seating portion 13 at the tip of the needle 5 is separated from the valve seat 11 and the valve portion 7 is opened (see FIG. 2).

  When electronic control is used in such an opening / closing operation of the valve unit 7, the magnitude relationship of the vertical force acting on the needle 5 varies depending on the energization state of the electromagnetic valve, the voltage application state to the piezo element, and the like. Be made. The fuel injection timing is controlled by the opening / closing timing of the valve unit 7, and intermittent fuel injection is performed by opening / closing the valve unit 7 while the fuel injection amount is controlled by the valve opening time of the valve unit 7. Is called.

  As described above, the fuel injection nozzle 1 of the present embodiment is formed with the nozzle body 4 having the fuel passage 3 for guiding the fuel to the nozzle hole 2, the nozzle hole 2 for ejecting the fuel at one end, and being inserted into the nozzle body 4. This is a shaft-like member that includes a nozzle body 4 and a needle 5 that constitutes a valve portion 7 that opens and closes the fuel passage 3 by reciprocating in the axial direction (vertical direction) with respect to the nozzle body 4. The operation method of the fuel injection nozzle 1, that is, the driving method of the needle 5 that reciprocates is not particularly limited.

  In the fuel injection nozzle 1, a hole 4 b for fitting the connecting pin 15 is formed in the nozzle body 4. The hole 4 b is formed so as to open in the end surface 4 a of the nozzle body 4. In the fuel injection valve constituted by the fuel injection nozzle 1, the connecting pin 15 connects the nozzle body 4 and the structure body 16 joined to the nozzle body 4 on the end face 4 a side. In the present embodiment, the hole 4b that opens to the end face 4a is provided at two locations so as not to interfere with the inlet 3a that also opens to the end face 4a (see FIG. 4), and the nozzle body 4 includes two connecting pins 15 Is used to connect to a predetermined structure 16.

  Below, the structure of the fuel path 3 with which the fuel injection nozzle 1 is provided is demonstrated concretely. As shown in FIG. 1 and the like, the fuel passage 3 includes a fuel supply passage portion 21, a direction changing passage portion 22, and a fuel reservoir portion 8 from the upstream side of the fuel flow with respect to the nozzle hole 2.

  The fuel supply passage portion 21 is provided at a predetermined position around the axis of the insertion hole formed by the guide surface 6 in the nozzle body 4 and forms a linear hole formed along the axial direction of the needle 5. It is a part to do. That is, the fuel supply passage 21 is a hole formed in the nozzle body 4 in parallel with the insertion hole formed by the guide surface 6 at a position shifted from the axial position. The fuel supply passage portion 21 has a substantially circular cross-sectional shape.

  The upstream (upper) end of the fuel supply passage 21 opens as an inlet 3 a of the fuel passage 3 on the end surface 4 a of the nozzle body 4. On the other hand, the downstream (lower) end of the fuel supply passage 21 is formed to extend to the position of the fuel reservoir 8 in the vertical direction. The downstream end of the fuel supply passage 21 faces the position spaced from the fuel reservoir 8, that is, the radially outer position of the needle 5 as viewed in the axial direction of the needle 5.

  The direction changing passage portion 22 is a portion that is provided between the fuel supply passage portion 21 and the fuel reservoir portion 8 and forms a linear hole that allows the fuel supply passage portion 21 and the fuel reservoir portion 8 to communicate with each other. The direction changing passage portion 22 guides the fuel into the fuel reservoir portion 8 from the downstream end portion of the fuel supply passage portion 21 facing the fuel reservoir portion 8 at a position spaced from the fuel reservoir portion 8 as described above.

  Therefore, the direction changing passage portion 22 is formed in a direction along a plane perpendicular to the axial direction of the needle 5. That is, the direction changing passage portion 22 sends the fuel sent along the axial direction of the needle 5 by the fuel supply passage portion 21 in a direction along a plane perpendicular to the axial direction of the needle 5. As described above, the direction changing passage portion 22 changes the flow direction of the fuel flowing along the axial direction of the needle 5 by the fuel supply passage portion 21 into a direction along a plane perpendicular to the axial direction of the needle 5. Then, the fuel is guided to the fuel reservoir 8.

  The direction changing passage portion 22 is formed along the tangential direction of the fuel reservoir 8 as viewed in the axial direction of the needle 5 with respect to the fuel reservoir 8. As shown in FIG. 5, the inner peripheral surface 9 forming the fuel reservoir portion 8 has an inner peripheral surface portion 23 that is circular when viewed in the axial direction of the needle 5. The direction changing passage portion 22 communicates with the fuel reservoir portion 8 in a tangential direction in a circular shape as viewed in the axial direction of the needle 5 by the inner peripheral surface portion 23.

  Specifically, as shown in FIG. 5, the inner peripheral surface 9 that forms the fuel reservoir portion 8 is an inner peripheral surface portion that has a circular shape centered on the axial center position O <b> 1 of the needle 5 as viewed in the axial direction of the needle 5. 23. In the circular shape centered on the axial center position O1, the tangent line O2 can be drawn at an arbitrary position.

  Therefore, in the direction changing passage portion 22 that forms a straight hole, the direction of the passage corresponding to the direction of the straight line is along the direction of the tangent line O2 in a circular shape centered on the axial center position O1. Provided. In other words, the direction changing passage portion 22 is formed such that the direction of the passage is parallel to the direction of the tangent line O2 in a circular shape centered on the axial center position O1.

  Further, in the fuel injection nozzle 1 of the present embodiment, the direction changing passage portion 22 constitutes a throttle between the fuel supply passage portion 21 and the fuel pool portion 8 constituting the fuel passage 3. That is, the direction changing passage portion 22 forms a flow passage having a hole diameter that functions as a restriction with respect to the passage areas of the fuel supply passage portion 21 and the fuel reservoir portion 8. The direction changing passage portion 22 restricts the flow rate of the fuel flowing from the fuel supply passage portion 21 into the fuel reservoir portion 8 by restricting the flow path between the fuel supply passage portion 21 and the fuel reservoir portion 8.

  Therefore, the flow path formed in the direction changing passage portion 22 is formed with a smaller diameter than the flow passage formed in the fuel supply passage portion 21. Further, the flow path formed in the direction change passage portion 22 is formed so as to open with a sufficiently small diameter with respect to the space formed in the fuel reservoir portion 8.

  The fuel reservoir 8 constituting the fuel passage 3 forms a space 18 for holding fuel around the axis of the needle 5 together with the outer peripheral surface of the needle 5, specifically the outer peripheral surface of the reduced diameter portion 12. . As shown in FIG. 1 and the like, the needle 5 inserted into the nozzle body 4 positions the reduced diameter portion 12 at the fuel reservoir 8 portion. Thereby, the fuel reservoir 8 forms a space 18 in which fuel is accumulated around the needle 5 by the inner peripheral surface 9 and the outer peripheral surface of the reduced diameter portion 12.

  The fuel flow through the fuel passage 3 configured as described above will be described. The fuel flow described here is the flow of fuel when fuel is injected from the nozzle hole 2, that is, the flow of fuel when the valve portion 7 is open.

  The fuel that is supplied to the fuel injection nozzle 1 through a predetermined path flows into the fuel supply passage portion 21 from the inlet portion 3 a of the fuel passage 3. The fuel that has flowed into the fuel supply passage 21 is guided downward along the axial direction of the needle 5 by the fuel supply passage 21 (see arrow A1 in FIG. 2).

  The fuel that has reached the lower end of the fuel supply passage portion 21 is changed in the flowing direction by flowing into the direction changing passage portion 22, and flows into the fuel reservoir 8 by the direction changing passage portion 22. The fuel flowing through the direction change passage portion 22 and flowing into the fuel reservoir portion 8 is provided to the fuel reservoir portion 8 because the direction change passage portion 22 is provided tangential to the fuel reservoir portion 8 as described above. It flows in the tangential direction (see arrow A2 in FIG. 5).

  The fuel flowing in the tangential direction with respect to the fuel reservoir 8 generates a swirling flow along the inner peripheral surface 9 in the fuel reservoir 8 (see arrow A3 in FIG. 5). In other words, the swirl flow of the fuel generated in the fuel reservoir 8 is a swirl flow around the axis of the needle 5.

  Further, cavitation occurs in the fuel flowing through the fuel passage 3 by the fuel flowing in the tangential direction from the direction changing passage portion 22 to the fuel reservoir portion 8. Occurrence of this cavitation is promoted by the direction changing passage portion 22 constituting a throttle in the fuel passage 3. That is, the direction change passage portion 22 that functions as a throttle restricts the flow rate of the fuel flowing from the fuel supply passage portion 21 into the fuel reservoir portion 8, so that cavitation tends to occur in the fuel flowing through the fuel passage 3. Become.

  The fuel that forms a swirling flow in the fuel reservoir 8 passes through a narrow gap between the valve seat 11 and the seating portion 13 of the needle 5 that are separated from each other when the valve portion 7 is in the open state. 10 flows out of the nozzle hole 2. In this way, the fuel injected from the fuel injection nozzle 1 ignites in the combustion chamber, spreads as a flame, and burns.

  Thus, in the flow of fuel guided to the nozzle hole 2 by the fuel passage 3, the fuel ejected from the nozzle hole 2 is a swirl flow generated by the fuel flowing into the fuel reservoir 8 from the direction changing passage section 22. Erupt while turning. In other words, the swirling flow of the fuel generated in the fuel reservoir 8 is also maintained in the tip passage portion 10 and the inside of the nozzle hole 2, and the fuel ejected from the nozzle hole 2 is jetted in a twisted state along the swirling flow. .

  In the fuel injection nozzle 1 of the present embodiment having the above-described configuration, the fuel supply passage portion 21 that constitutes the fuel passage 3 functions as a first passage portion, and the direction changing passage that also constitutes the fuel passage 3. The part 22 functions as a second passage part.

  That is, the fuel supply passage portion 21 is provided upstream of the fuel reservoir portion 8 in the fuel passage 3 and guides the fuel toward the insertion direction side (lower side) of the needle 5 with respect to the nozzle body 4. The direction changing passage 22 is provided between the fuel reservoir 8 and the fuel supply passage 21 and is formed in a direction along a plane perpendicular to the axial direction of the needle 5. Thus, the needle 5 communicates in a direction shifted from the radial direction of the needle 5.

  According to the fuel injection nozzle 1 as described above, a swirl flow can be generated inside the nozzle body 4 at a low cost with a simple structure, and atomization of the injected fuel can be promoted. It can contribute to improvement of combustibility and exhaust characteristics.

  Specifically, the fuel injection nozzle 1 of the present embodiment is configured such that in the fuel supply path to the nozzle hole 2, in addition to the fuel supply passage section 21 that guides fuel in the axial direction of the needle 5, A direction changing passage portion 22 communicating in a tangential direction with respect to the portion 8 is provided. As a result, the fuel injection nozzle 1 generates a swirling flow in the fuel reservoir 8 that is inside the nozzle body 4. For this reason, according to the fuel injection nozzle 1 of the present embodiment, a simple structure and low cost can be easily realized without causing complication of the shape of the needle 5 by devising the shape of the outer peripheral surface of the needle 5, for example. In addition, the swirl flow can be effectively generated inside the nozzle body 4.

  Furthermore, according to the fuel injection nozzle 1 of the present embodiment, the effect of preventing dripping (slipping) of the fuel after the injected fuel is combusted is also obtained. This is considered to be based on the fact that liquid breakage in the nozzle hole 2 is improved by the swirling flow generated inside the nozzle body 4.

  Further, in the fuel injection nozzle 1 of the present embodiment, the direction changing passage portion 22 that generates the swirling flow in the fuel reservoir portion 8 forms a throttle in the fuel passage 3. Thereby, cavitation can be positively generated in the fuel flowing through the fuel passage 3 in the nozzle body 4.

  In this regard, although the details of the mechanism of cavitation generation have not yet been clarified by conventional research, it has been reported that cavitation generated inside the nozzle body contributes to atomization of the injected fuel. That is, it is known that atomization of the injected fuel is promoted by the occurrence of cavitation inside the nozzle body.

  Therefore, according to the fuel injection nozzle 1 of the present embodiment, the flow path configuration of the fuel passage 3 promotes the generation of cavitation for the fuel flowing through the fuel passage 3, and effectively promotes atomization of the injected fuel. . As a result, according to the fuel injection nozzle 1 of the present embodiment, fuel combustibility and exhaust characteristics are improved.

  In the fuel injection nozzle 1 of the present embodiment, the direction changing passage portion 22 constituting the fuel passage 3 communicates with the fuel reservoir portion 8 in the tangential direction, but is not limited thereto. That is, in the present embodiment, the tangential direction with respect to the fuel reservoir 8 is adopted as the direction deviating from the radial direction of the needle 5 with respect to the direction of communication of the direction changing passage 22 with respect to the fuel reservoir 8. Not.

  Therefore, with respect to the direction of communication of the direction changing passage 22 with respect to the fuel reservoir 8, the direction deviated from the radial direction of the needle 5 is the tangential direction with respect to the fuel reservoir 8 from the viewpoint of obtaining the effects described above. The direction in which the amount of deviation from the radial direction is maximized may be a direction that deviates from the radial direction of the needle 5 to the extent that a swirling flow is generated in the fuel reservoir 8.

  The direction along the plane perpendicular to the axial direction of the needle 5 with respect to the direction in which the direction changing passage portion 22 is formed in the nozzle body 4 is along the plane strictly perpendicular to the axial direction of the needle 5. It is not limited to the direction, and includes a direction along a plane substantially perpendicular to the axial direction of the needle 5.

  As the direction in which the direction changing passage portion 22 is formed, the fuel supplied along the axial direction of the needle 5 by the fuel supply passage portion 21 whose downstream end reaches the position of the fuel reservoir 8 is the fuel supply. In a direction along a plane substantially perpendicular to the axial direction of the needle 5 to such an extent that the direction is changed so as to be guided to the fuel reservoir 8 located inside the passage portion 21 (on the axial center position side of the needle 5). I just need it.

  Further, in the fuel injection nozzle 1 of the present embodiment, the fuel supply passage portion 21 constituting the fuel passage 3 is formed along the axial direction of the needle 5, that is, parallel to the insertion hole of the needle 5. It is not limited to. The fuel supply passage portion 21 does not need to be parallel to the axial direction of the needle 5, and may be any configuration as long as the fuel is guided toward the insertion direction side (lower side) of the needle 5 with respect to the nozzle body 4.

  Therefore, the direction of the fuel supply passage portion 21 may be an oblique direction with respect to the axial direction of the needle 5. Here, the flow path length of the direction changing passage portion 22 is increased as the position of the downstream end portion of the fuel supply passage portion 21 is separated from the fuel reservoir portion 8 in the axial view of the needle 5. It is easy to ensure.

  Further, in the fuel injection nozzle 1 of the present embodiment, the fuel supply passage portion 21 and the direction changing passage portion 22 are both formed in a straight line shape, but the shape of each passage portion is not particularly limited. For the fuel supply passage portion 21 and the direction changing passage portion 22, for example, the connecting portion of both passage portions may be formed in a curved shape, or each passage portion may be formed in a curved shape as a whole or in part. .

  Further, in the fuel injection nozzle 1 of the present embodiment, one set of the fuel supply passage portion 21 and the direction changing passage portion 22 constituting the fuel passage 3 is provided, but a plurality of sets of the fuel supply passage portion 21 and the direction changing passage are provided. The part 22 may be configured to communicate with the fuel reservoir 8. In this case, the plurality of direction change passage portions 22 are provided with respect to the fuel reservoir portions 8 so that the swirl flows generated in the fuel reservoir portions 8 by the respective direction change passage portions 22 are not offset from each other.

  For example, when two sets of fuel supply passage portions 21 and direction change passage portions 22 are provided, and each direction change passage portion 22 communicates tangentially to the fuel reservoir portion 8, the two direction change passage portions 22 are: The needle 5 is provided point-symmetrically with respect to the axial center position O1 (see FIG. 5) of the needle 5 as viewed in the axial direction. As described above, by adopting a configuration in which a plurality of sets of fuel supply passage portions 21 and direction changing passage portions 22 communicate with the fuel reservoir portion 8, the swirl flow is made more effective in the fuel reservoir portion 8. Can be generated.

  In the fuel reservoir 8, the inner peripheral surface portion 23 that is circular when viewed in the axial direction of the needle 5 is not limited to a perfect circle, but a portion that is circular in shape. Including the substantially circular shape including. That is, the circular shape of the inner peripheral surface portion 23 in the axial view of the needle 5 is to define the tangential direction when the direction changing passage portion 22 communicates with the fuel reservoir 8 in the tangential direction. Since it is a shape, the circular shape about the inner peripheral surface part 23 should just be a substantially circular shape which has the part which becomes circular arc shape so that a tangential direction can be prescribed | regulated.

  In addition, the space 18 formed by the fuel reservoir 8 preferably has a tapered shape that is reduced in diameter toward the downstream side along the axial direction of the needle 5 as in the fuel injection nozzle 1 of the present embodiment. . Specifically, as shown in FIG. 1 and the like, the space 18 formed by the inner peripheral surface 9 in the fuel reservoir 8 is from the upper side that becomes a diameter-enlarged portion with respect to the insertion hole of the needle 5 formed by the guide surface 6. In addition, it has a substantially conical shape that gradually decreases in diameter toward the lower side (downstream side) where the distal end passage portion 10 opens.

  As described above, the space 18 formed by the fuel reservoir 8 has a tapered shape toward the fuel injection side, so that a vortex is easily generated in the fuel flow from the fuel reservoir 8 toward the tip passage portion 10. . Thereby, the momentum of the swirling flow generated in the fuel reservoir 8 can be maintained or amplified, and atomization by the swirling flow can be promoted more effectively.

  Further, the fuel injection nozzle 1 of the present embodiment has one injection hole 2 through which fuel is injected, but may have a plurality of injection holes 2. When the fuel injection nozzle 1 has a plurality of injection holes 2, for example, as shown in FIG. 6, the plurality of injection holes 2 radiate fuel radially downward with the axial center of the needle 5 as the center. It is formed to erupt.

  Further, for example, as shown in FIG. 7, the plurality of nozzle holes 2 may be formed along the tangential direction with respect to the tip passage portion 10 having a circular shape when the needle 5 is viewed in the axial direction. FIG. 7 shows a case where eight nozzle holes 2 are formed along the tangential direction with respect to the distal end passage portion 10 at equal intervals in the circumferential direction of the distal end passage portion 10 as viewed in the axial direction of the needle 5. An example is shown.

  Examples of the present invention will be described below. In this example, a fuel injection nozzle (hereinafter referred to as “example product”) to which the fuel injection nozzle 1 of the above-described embodiment is applied, and a fuel injection nozzle (hereinafter referred to as “example product”) as a comparison target of the example product (hereinafter referred to as “example product”). "Comparative Example Product") is an analysis of fuel combustion and injected fuel. In this embodiment, light oil mainly used as fuel for diesel engines is used as the fuel to be injected.

  In the description of the present embodiment, the fuel injection nozzle 31 as a comparative example product will be described with reference to FIG. In the description of the fuel injection nozzle 31 as a comparative example product, for the sake of convenience, portions common to the fuel injection nozzle 1 of the embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8, the fuel injection nozzle 31 as a comparative example has a straight passage portion 41 as a fuel passage for guiding fuel from the inlet portion 3 a to the fuel reservoir portion 8. The straight passage portion 41 is a portion that forms a straight hole from the inlet portion 3 a to the peripheral edge portion of the fuel reservoir portion 8.

  The straight passage portion 41 is inclined with respect to the axial direction of the needle 5 so as to approach the axial center position of the needle 5 from the inlet portion 3a to the nozzle hole 2 side along a cross section passing through the axial center line of the needle 5. Formed in the direction. As described above, the fuel injection nozzle 31 as a comparative product is a fuel reservoir from the inlet 3a in place of the fuel supply passage 21 and the direction change passage 22 in comparison with the fuel injection nozzle 1 of the above-described embodiment. The fuel injection nozzle 1 differs from the fuel injection nozzle 1 in that it has a straight passage portion 41 that is a straight passage that guides fuel directly to the portion 8.

  Next, the configuration of the analysis apparatus used in this example will be described with reference to FIG. As shown in FIG. 9, the analysis device 51 used in this embodiment includes a combustion chamber 52, a preliminary combustion adjustment unit 53, a fuel supply unit 54, a photo sensor 55, a camera 56, and a control unit 57. Prepare.

  The combustion chamber 52 forms a combustion space 60 for burning fuel. In this embodiment, the combustion space 60 is formed as a substantially cylindrical space having a diameter of 100 mm and a height of 330 mm. The combustion chamber 52 is configured as a metal container.

  An observation window 61 is provided in the combustion chamber 52. The observation window 61 is a window for observing the state of fuel combustion inside the combustion chamber 52 from the outside of the combustion chamber 52. The observation window 61 is provided in a peripheral wall portion that forms the combustion space 60 in the combustion chamber 52. The observation window 61 is configured so that the inside of the combustion chamber 52 can be seen through the quartz glass 62 from the outside of the combustion chamber 52. The quartz glass 62 is attached to a peripheral wall portion that forms the combustion space 60. The observation window 61 has a substantially elliptical shape with a height of 280 mm and a width of 50 mm (see FIG. 14).

  The combustion chamber 52 is provided with a fuel injection nozzle for injecting fuel into the combustion chamber 52. That is, when analyzing an example product, the fuel injection nozzle 1 of the above-described embodiment is provided in the combustion chamber 52. When analyzing a comparative example product, the fuel injection nozzle 31 as a comparative example product is provided. Is provided in the combustion chamber 52. In the description of the analysis device 51, a case where the fuel injection nozzle 1 as an example product is provided will be described as an example.

  The fuel injection nozzle 1 is provided in the upper part of the combustion chamber 52 so that the injection hole 2 side faces downward. Thus, in this embodiment, the fuel injected from the fuel injection nozzle 1 is burned in the combustion chamber 52.

  The combustion chamber 52 is provided with a spark plug 64. The spark plug 64 is attached to a peripheral wall portion that forms the combustion space 60 in the combustion chamber 52, and is connected to an igniter (not shown). The spark plug 64 is for igniting the mixed gas supplied from the preliminary combustion adjusting unit 53 to the combustion chamber 52 as will be described later. The operation of the spark plug 64 is controlled by the control unit 57.

  Further, an exhaust pipe 65 for exhausting the combustion gas in the combustion chamber 52 is connected to the combustion chamber 52. The exhaust pipe 65 is provided with an exhaust control valve 66. The exhaust control valve 66 is a valve for switching between an exhaust state in which combustion gas is exhausted from the combustion chamber 52 and a non-exhaust state in which exhaust of combustion gas from the combustion chamber 52 is stopped. The exhaust control valve 66 is provided in the vicinity of the connection portion of the exhaust pipe 65 to the combustion chamber 52.

  The exhaust pipe 65 is provided at a downstream side of the exhaust control valve 66 for natural exhaust pipe 65 a for performing natural exhaust utilizing the high pressure state in the combustion chamber 52 and for forced exhaust by the vacuum pump 67. It branches to the forced exhaust pipe 65b. The exhaust pipe 65 exhausts the combustion chamber 52 so that a combustion residue does not remain in the combustion chamber 52 as much as possible by forced exhaust of the combustion gas in the combustion chamber 52 by the vacuum pump 67.

  The natural exhaust pipe 65a and the forced exhaust pipe 65b constituting the exhaust pipe 65 are provided with switching on-off valves 68a and 68b. By opening / closing control of these on-off valves 68a and 68b, the combustion gas in the combustion chamber 52 is exhausted efficiently and promptly. The operation of the exhaust control valve 66 and the on-off valves 68a and 68b provided in the exhaust pipe 65 is controlled by the control unit 57. Further, the combustion chamber 52 is provided with a safety valve 69 for ensuring safety in a situation where a change in the atmospheric pressure in the combustion chamber 52 occurs.

  The combustion chamber 52 is provided with a combustion chamber thermometer 71 for measuring the initial temperature in the combustion chamber 52 and a combustion chamber pressure gauge 72 for measuring the pressure in the combustion chamber 52. Yes. The combustion chamber thermometer 71 is a thermocouple, and the combustion chamber pressure gauge 72 is a pressure conversion element.

  The preliminary combustion adjustment unit 53 is a configuration for adjusting the temperature, pressure, and atmosphere state including gas components in the combustion chamber 52. That is, the preliminary combustion adjustment unit 53 adjusts the atmospheric state in the combustion chamber 52 to a predetermined state in advance by causing combustion in the combustion chamber 52.

  The preliminary combustion adjustment unit 53 includes an adjustment gas tank 81 and an ethylene gas tank 82. The adjustment gas tank 81 stores adjustment gas composed of oxygen mixed with nitrogen, and is connected to the combustion chamber 52 via the adjustment gas supply pipe 83. The ethylene gas tank 82 stores ethylene gas as a fuel gas and is connected to the combustion chamber 52 via an ethylene gas supply pipe 84.

  In other words, the preliminary combustion adjustment unit 53 supplies the adjustment gas in the adjustment gas tank 81 into the combustion chamber 52 through the adjustment gas supply pipe 83 and the ethylene gas in the ethylene gas tank 82 through the ethylene gas supply pipe 84. Is fed into the combustion chamber 52. In the present embodiment, the adjustment gas supply pipe 83 and the ethylene gas supply pipe 84 are connected to the combustion chamber 52 in a state where they are joined together.

  The adjustment gas supply pipe 83 and the ethylene gas supply pipe 84 are provided with a mass flow controller 85 and a control valve 86, respectively. The mass flow controller 85 and the control valve 86 provided in the adjustment gas supply pipe 83 adjust the flow rate of the adjustment gas supplied from the adjustment gas tank 81 to the combustion chamber 52. A mass flow controller 85 and a control valve 86 provided in the ethylene gas supply pipe 84 adjust the flow rate of ethylene gas supplied from the ethylene gas tank 82 to the combustion chamber 52.

In this way, the adjustment gas and the ethylene gas whose flow rates are adjusted by the preliminary combustion adjustment unit 53 are sent into the combustion chamber 52, so that oxygen (O ₂ ), nitrogen (N ₂ ), and A premixed gas in which ethylene (C ₂ H ₄ ) is mixed at a predetermined ratio is generated. In the present embodiment, the adjustment gas stored in the adjustment gas tank 81 is a gas having a component ratio of 34% oxygen and 66% nitrogen.

  The fuel supply unit 54 is configured to supply the fuel to be analyzed by the analysis device 51 into the combustion chamber 52. The fuel supply unit 54 has a fuel tank 91. The fuel tank 91 stores fuel to be analyzed, and is connected to the fuel injection nozzle 1 through a fuel supply pipe 92. That is, the fuel supply unit 54 supplies the fuel in the fuel tank 91 to the fuel injection nozzle 1 through the fuel supply pipe 92.

  The fuel supply unit 54 includes a compressor 93 and a fuel pump 94 as a configuration for supplying fuel to the fuel injection nozzle 1 while being pressurized to a predetermined pressure. The compressor 93 is connected to the fuel tank 91 and pressurizes the fuel tank 91. The fuel pump 94 is provided in the fuel supply pipe 92 and pressure-feeds the fuel sent from the fuel tank 91 to the fuel supply pipe 92 to the fuel injection nozzle 1.

  The fuel pump 94 has a piston 94a that is operated by hydraulic oil, and operates by receiving supply of hydraulic oil. Supply of the hydraulic oil to the fuel pump 94 is performed by a configuration including an oil pump 95 and an accumulator 96. The oil pump 95 and the accumulator 96 are connected to the fuel pump 94 via a solenoid valve 97.

  In the fuel supply unit 54, the fuel pressurized by the compressor 93 is further pressurized by the piston 94 a that receives and is pressed by the hydraulic oil pressurized by the accumulator 96 and is supplied to the fuel injection nozzle 1. The operation of the electromagnetic valve 97 is controlled by the control unit 57. Stable fuel injection from the fuel injection nozzle 1 to the combustion space 60 is performed by the fuel supply unit 54 having the above-described configuration.

  Further, a drain pipe 98 for discharging excess fuel out of the fuel supplied from the fuel supply section 54 to the fuel injection nozzle 1 is connected to a connection portion between the fuel supply pipe 92 and the fuel injection nozzle 1. . The fuel discharged by the drain pipe 98 is stored in the drain tank 99. The drain pipe 98 is provided with an on-off valve 100.

  In the analysis device 51, a fuel thermometer 101 for measuring the temperature of fuel injected from the fuel injection nozzle 1, and a fuel pressure for measuring the pressure of fuel injected from the fuel injection nozzle 1. A total of 102 is provided. The fuel thermometer 101 is a thermocouple and is provided in the fuel supply pipe 92. The fuel pressure gauge 102 is a pressure conversion element and is connected to the fuel injection nozzle 1.

  The photosensor 55 is for receiving the light of the flame accompanying the combustion of fuel in the combustion chamber 52 and detecting the light. In the present embodiment, the photosensors 55 are arranged at three locations with a predetermined interval in the vertical direction. In FIG. 9, for convenience of explanation, the photosensor 55 is shown facing the inside of the combustion chamber 52 from the observation window 61. However, in this embodiment, the photosensor 55 is a peripheral wall that forms the combustion space 60 in the combustion chamber 52. It is provided in a manner embedded in the part.

  A detection signal from the photosensor 55 is input to the control unit 57. By using the photosensor 55, the time resolution can be improved very easily when observing the combustion state of the fuel, and the fuel combustion state can be accurately and reliably measured.

  The camera 56 is a high-speed video camera, and is for acquiring image data regarding the combustion state of fuel in the combustion chamber 52. The camera 56 is arranged so as to face the observation window 61 of the combustion chamber 52, and photographs the state of combustion including the behavior of the flame accompanying the combustion of fuel in the combustion chamber 52 through the observation window 61 at a high photographing speed. .

  Image data acquired by the camera 56 is input to the control unit 57. In the present embodiment, the camera 56 acquires image data at a time interval of 0.5 ms (milliseconds). That is, the camera 56 images the state in the combustion chamber 52 every 0.5 ms.

  The control unit 57 controls each unit of the analysis device 51 based on a predetermined program. The control unit 57 includes a storage unit that stores programs and the like, a calculation unit that performs predetermined calculations according to the programs and the like, a storage unit that stores calculation results and the like by the calculation units, and the like. The control unit 57 is a computer having a configuration in which a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like are connected by a bus or the like.

  The control unit 57 controls the preliminary combustion adjusting unit 53 and the fuel supply unit 54 to burn the fuel in the combustion chamber 52. The control unit 57 executes a predetermined analysis process based on data obtained by the photosensor 55 and the camera 56 regarding the combustion of fuel in the combustion chamber 52.

  In order to burn the fuel in the combustion chamber 52, the controller 57 first burns the premixed gas in the combustion chamber 52, thereby filling the combustion chamber 52 with pseudo air of a predetermined pressure and temperature. To do. The control unit 57 controls the preliminary combustion adjusting unit 53 and the spark plug 64 to burn the premixed gas in the combustion chamber 52.

Specifically, the control unit 57 controls the mass flow controller 85 and the control valve 86 in the preliminary combustion adjustment unit 53 so as to supply the adjustment gas and the ethylene gas to the combustion chamber 52 by a predetermined amount. In addition, oxygen (O ₂ ), nitrogen (N ₂ ), and ethylene (C ₂ H ₄ ) are mixed at a predetermined ratio to generate a premixed gas.

  The control unit 57 stops the supply of the adjustment gas and the ethylene gas from the preliminary combustion adjustment unit 53 to the combustion chamber 52 when the premixed gas is filled in the combustion chamber 52. The control unit 57 stops the gas supply to the combustion chamber 52 and then transmits a signal to an igniter connected to the ignition plug 64 to operate the ignition plug 64 so that the combustion chamber 52 is filled. Burn premixed gas.

  As the premixed gas burns in the combustion chamber 52, the pressure in the combustion chamber 52 increases. As the premixed gas burns, pseudo air is generated in the combustion chamber 52. In the present embodiment, the pressure and component ratio of the premixed gas were adjusted so that 21% oxygen was present in the pseudo air generated in the combustion chamber 52. Here, the oxygen amount (oxygen concentration) in the pseudo air generated in the combustion chamber 52 is the amount of oxygen in the adjustment gas supplied from the preliminary combustion adjustment unit 53 to the combustion chamber 52 or the combustion chamber 52. It adjusts by the mixing ratio etc. of the supplied adjustment gas and ethylene gas.

  The pressure in the combustion chamber 52 that has increased due to the combustion of the premixed gas gradually decreases due to heat loss. In the process in which the pressure in the combustion chamber 52 decreases, fuel is burned by injecting fuel from the fuel injection nozzle 1 at a predetermined timing. That is, the control unit 57 controls the fuel supply unit 54 from a state in which the interior of the combustion chamber 52 is filled with the pseudo air by controlling the preliminary combustion adjusting unit 53 and the spark plug 64, so that the fuel is supplied at a predetermined timing. Fuel is injected from the injection nozzle 1 to cause combustion of fuel in the combustion chamber 52.

  Specifically, the controller 57 controls the solenoid valve 97 when the pressure in the combustion chamber 52 reaches a predetermined set pressure in the process of decreasing the pressure in the combustion chamber 52 that has been increased by the combustion of the premixed gas. By operating the fuel pump 94 by switching control, fuel is injected from the fuel injection nozzle 1 into the combustion chamber 52.

  In the present embodiment, the fuel injection from the fuel injection nozzle 1 under the control of the control unit 57 is performed when the pressure in the combustion chamber 52 reaches 1.9 MPa (megapascals). The atmosphere in the combustion chamber 52 was adjusted so that the temperature in the combustion chamber 52 was 684K while the pressure in the combustion chamber 52 was 1.9 MPa.

  In the present embodiment, as another case, the fuel injection from the fuel injection nozzle 1 under the control of the control unit 57 is performed when the pressure in the combustion chamber 52 reaches 1.8 MPa. Then, the atmospheric state in the combustion chamber 52 was adjusted such that the temperature in the combustion chamber 52 was 648K while the pressure in the combustion chamber 52 was 1.8 MPa.

  Hereinafter, the atmospheric state in which the atmospheric pressure (Pa) in the combustion chamber 52 is 1.9 MPa and the atmospheric temperature (Ta) is 684K is referred to as “first temperature state”, and the atmospheric pressure in the combustion chamber 52 is 1.8 MPa. An atmospheric state having an atmospheric temperature of 648K is referred to as a “second temperature state”.

  The fuel injected from the fuel injection nozzle 1 into the combustion chamber 52 is self-ignited by the atmospheric state in the combustion chamber 52 and starts to burn. In other words, injecting fuel into the combustion chamber 52 is a process in which the atmospheric conditions such as pressure and temperature in the combustion chamber 52 cause the natural ignition of the injected fuel in the process in which the pressure in the combustion chamber 52 decreases. It is performed when it is in a state to be generated. As the fuel injected from the fuel injection nozzle 1 burns in the combustion chamber 52, the pressure in the combustion chamber 52 temporarily rises in the process of gradually decreasing.

  Thus, the fuel combusted in the combustion chamber 52 is stably supplied by the fuel supply unit 54. The pressure of fuel injected into the combustion chamber 52 from the fuel injection nozzle 1 (hereinafter referred to as “fuel injection pressure”) is measured by the fuel pressure gauge 102 as described above. The fuel is injected into the combustion chamber 52 for about 30 ms.

  The controller 57 exhausts the combustion gas in the combustion chamber 52 after the combustion of the fuel in the combustion chamber 52 is completed. The control unit 57 performs exhaust by opening the open / close valve 68a of the exhaust control valve 66 and the natural exhaust pipe 65a as exhaust of the combustion gas in the combustion chamber 52, and the open / close valve of the exhaust control valve 66 and the forced exhaust pipe 65b. 68b is opened and forced evacuation is performed by operating the vacuum pump 67.

  Using the analysis device 51 having the above-described configuration, as an example of the present invention, analysis of fuel combustion and injected fuel was performed.

  10 and 11 show a total of 41 continuous captured images (for 20 ms) including the time of fuel ignition in the combustion chamber 52, each acquired by the camera 56. FIG. That is, each figure of FIG. 10 and FIG. 11 shows the state of combustion after the start of fuel injection. 10 and FIG. 11, each portion divided by a rectangle is one captured image (image data), and a white portion in each captured image represents a flame portion, and a black portion represents a background. In addition, the image data in each of FIGS. 10 and 11 has a common time axis based on the fuel injection timing.

  FIG. 10A shows the state of combustion when the atmospheric condition at the time of fuel injection is the first temperature state (Pa = 1.9 MPa, Ta = 684K) and the analysis apparatus 51 uses the example product. FIG. 10B shows the state of combustion when the atmospheric condition is also set to the first temperature state and a comparative example product is used in the analysis device 51.

  FIG. 11A shows the state of combustion when the atmospheric condition at the time of fuel injection is the second temperature state (Pa = 1.8 MPa, Ta = 648 K) and the analysis apparatus 51 uses the example product. FIG. 11B shows the state of combustion when the atmospheric condition is set to the second temperature state and the comparative product is used in the analysis device 51.

10 (a), 10 (b), 11 (a), and 11 (b), the upper data indicates the case where the fuel injection pressure (P _inj ) is 32 MPa, and the middle data indicates the fuel injection. The case where the pressure is 40 MPa is shown, and the lower data shows the case where the fuel injection pressure is 80 MPa. Further, in any case shown in FIGS. 10 and 11, the oxygen concentration as the atmospheric condition was set to 21%.

  As can be seen from the comparison between FIGS. 10A and 10B, the ignition delay was almost the same between the example product and the comparative product. Here, the ignition delay is the time from the fuel injection to the ignition by the fuel injection nozzle, that is, from the time when the fuel injection is started by the fuel injection nozzle to the time when the fuel injected from the fuel injection nozzle is ignited. It's time.

  Further, from the comparison between FIGS. 10A and 10B, it can be seen that the flame of the example product is thicker than that of the comparative example product regarding the combustion after the ignition of the fuel. That is, the example product has a larger extent of the lateral spread of the flame due to the combustion after ignition.

  The flame of the example product is thicker than that of the comparative example product. The fuel of the example product burns in a state where the injection angle of the sprayed fuel is wider than that of the comparative example product. It is presumed to be caused by the fact that the combustion is less.

  Further, from comparison of the upper, middle, and lower data of FIGS. 10A and 10B, the flame of the example product is thicker than the comparative example product even when the fuel injection pressure changes. I understand that. That is, the flame spreading effect of the embodiment product can be obtained without being particularly affected by the fuel injection pressure.

  As can be seen from FIGS. 11A and 11B, even in the second temperature state, the state of fuel combustion shows the same tendency as in the first temperature state shown in FIG. That is, even in the second temperature state, the flame of the example product is thicker than the comparative example product without being particularly affected by the fuel injection pressure. 10 and FIG. 11, it can be seen that the flame spread effect of the example product can be obtained without being particularly affected by the atmospheric conditions (particularly even in a state where the atmospheric temperature is low).

As described above, according to the example product, the spread of the flame is increased in comparison with the comparative example product to which the related art is applied. A large flame spread indicates that the fuel is atomized. By this example, it was demonstrated that atomization of the injected fuel was promoted by the swirl flow generated inside the nozzle body by using the example product.

  Further, in this example, regarding the combustion of fuel, the state of afterburning after the valve portion 7 of the fuel injection nozzle was closed was observed. FIG. 12 shows a total of 21 continuous captured images (for 10 ms) representing the state of combustion (afterburning) after the end of fuel injection in the combustion chamber 52, acquired by the camera 56. .

In FIG. 12, each part delimited by a rectangle is one captured image (image data). One frame is 0.5 ms. FIG. 12A shows data for the example product, and FIG. 12B shows data for the comparative example product. 12A and 12B has a common time axis based on the fuel injection timing. The atmospheric conditions when acquiring the data shown in FIG. 12 are Pa = 1.9 MPa, Ta = 684K (first temperature state), and the fuel injection pressure (P _inj ) is P _inj = 32 MPa.

  As shown in FIG. 12 (b), in the case of the comparative example product, there is fuel behind after the end of fuel injection, and after that, it can be seen that the fuel is burning (see the broken line oval part). In this regard, as shown in FIG. 12A, in the case of the embodiment product, there is almost no dripping after the end of fuel injection.

  From this, it can be seen that the example product has good spraying of fuel after completion of fuel injection. Similar observations were made under other conditions with respect to atmospheric conditions and fuel injection pressures, etc., but all were in the same trend as in the present example. I couldn't find it.

  In this example, it was proved that the use of the example product suppresses the trailing of the fuel that occurred in the case of the comparative example product to which the conventional technology is applied. In this way, according to the embodiment product that can suppress the dripping of the fuel, the fuel injected from the nozzle can be burned cleanly, so in the actual machine, the fuel efficiency is improved, the combustion chamber is improved, the engine cylinder is improved. Benefits such as improving the corrosive environment on the liner surface are significant.

  Next, consideration will be given to the fuel flow rates of the example product and the comparative product. Regarding the example product, since the direction changing passage portion 22 is configured as a restriction in the fuel passage 3, there is a concern that the flow rate of the fuel may be reduced compared to the comparative example product. Therefore, in this example, the change in the atmospheric pressure accompanying fuel combustion was measured.

FIG. 13 shows the change over time in the atmospheric pressure accompanying the combustion of fuel for the example product and the comparative product. In the graph shown in FIG. 13, the horizontal axis indicates time (ms), the vertical axis indicates the atmospheric pressure (MPa), the solid line is a graph for the example product, and the alternate long and short dash line is the graph for the comparative example product. . The measurement results shown in FIG. 13 were obtained under the atmospheric conditions of Pa = 1.9 MPa, Ta = 684K, and P _inj = 80 MPa.

  From the measurement results shown in FIG. 13, it can be seen that the atmospheric pressure during the process of fuel combustion increases in the same way for the example product and the comparative product. This indicates that there is almost no difference in the amount of fuel injected per unit time between the example product and the comparative product. Here, since the combustion chamber 52 of the analyzer 51 is a constant volume container, the value of the atmospheric pressure indicated by the vertical axis in the graph of FIG. 13 corresponds to the amount of heat generated per unit time. That is, as the value of the atmospheric pressure increases, the amount of heat generation per unit time also increases.

  As described above, the embodiment example and the comparative example product in FIG. 13 have the same increase in the atmospheric pressure, and therefore the direction change passage portion 22 is configured as a restriction in the fuel passage 3 of the example product. Does not particularly affect the flow rate of the fuel. In FIG. 13, at the end of heat generation after around 25 ms, the example product has a lower atmospheric pressure value than the comparative example product. In this measurement example, the example product has a slightly shorter injection period. This is because the heat generation amount per unit time is considered to be substantially the same between the example product and the comparative example product.

  In addition, the fuel injection amount per unit time of the example product and the comparative example product is about the same, because the spread of the flame is increased by using the example product as described above. It can be said that the fuel injected from the product burns more efficiently.

  Subsequently, as this example, the state of fuel spraying in the vicinity of the fuel injection nozzle was photographed. Here, in the analysis apparatus 51 described above, a high-speed camera that acquires image data of 1 million frames per second was used as the camera 56 to photograph the state of fuel spray.

  In the case of a spray flame, since the fuel flow rate is fast, there is no flame near the fuel injection nozzle and a spray state is present. For this reason, in this embodiment, as shown in FIG. 14, the state of fuel spraying immediately below the nozzle hole 2 of the fuel injection nozzle 1 (31) was photographed.

Specifically, as shown in FIG. 14, a rectangular range of 5 mm in length and 6 mm in width is taken as an imaging range (imaging frame), and the vertical direction is downward with respect to the position of the tip of the fuel injection nozzle 1 (31). Regarding the position in the (Z direction), photographing was performed every vertical length (5 mm) of the photographing frame. In this example, the fuel injection pressure was 32 MPa (P _inj = 32 MPa).

  FIG. 15 shows an example product and a comparative product at a Z = 15 mm position (see FIG. 14, “shooting frame F1”) and a Z = 20 mm position (see FIG. 14, “shooting frame F2”). The photographed result (one frame of image data) is shown, with the black part representing the sprayed fuel and the white part representing the background in each photographed photograph.

  Consider the imaging results shown in FIG. Although the spray shape of the fuel injected from the fuel injection nozzle changes with time, each photograph shown in FIG. 15 represents a standard spray state. When the spray shapes of the example product and the comparative product are compared, it can be seen that the spray shape of the example product is swollen. This phenomenon is considered to be because the liquid fuel injected from the nozzle holes 2 is more atomized and spread in the example product than in the comparative product.

  Thus, it was proved that atomization of the injected fuel is promoted by the swirl flow generated inside the nozzle body by using the example product from the state of fuel spray in the vicinity of the fuel injection nozzle. .

  The present invention can be widely applied to injection of liquid fuels such as biodiesel fuel, alcohol fuel, and other synthetic fuels in addition to petroleum fuel including diesel fuel (bunker oil) and gasoline. Therefore, the fuel injection nozzle according to the present invention can be widely applied to, for example, marine and automobile diesel engines, gasoline engines, and the like regardless of the fuel injection method such as the direct injection type and the sub-chamber type. The present invention is widely deployed in the technical fields where fuel injection is performed, such as the field of marine engineering and mechanical engineering, and further the field of food processing and the field of painting.

DESCRIPTION OF SYMBOLS 1 Fuel injection nozzle 2 Injection hole 3 Fuel passage 4 Nozzle main body 5 Needle 6 Guide surface 7 Valve part 8 Fuel reservoir part 9 Inner peripheral surface 12 Reduced diameter part 18 Space 21 Fuel supply passage part (1st passage part)
22 Direction change passage part (second passage part)
23 Inner peripheral surface

Claims (4)

A nozzle body having a fuel passage for injecting fuel at one end and having a fuel passage for guiding fuel to the nozzle hole;
A shaft-shaped member that is inserted into the nozzle body, and includes a needle that, together with the nozzle body, constitutes a valve portion that opens and closes the fuel passage by axial reciprocation relative to the nozzle body,
The fuel passage is
A fuel reservoir that forms a space for holding fuel around the axis of the needle together with the outer peripheral surface of the needle;
A first passage portion that is provided on the upstream side of the fuel reservoir portion and guides fuel toward an insertion direction side of the needle with respect to the nozzle body;
Provided between the fuel reservoir and the first passage, and formed in a direction along a plane perpendicular to the axial direction of the needle, with respect to the fuel reservoir from the radial direction of the needle A second passage portion communicating in the shifted direction,
Fuel injection nozzle. The second passage portion constitutes a restriction for the fuel reservoir portion and the first passage portion.
The fuel injection nozzle according to claim 1. The fuel reservoir has an inner peripheral surface portion that is circular when viewed in the axial direction of the needle,
The second passage portion communicates with the fuel reservoir portion in a tangential direction in the circular shape.
The fuel injection nozzle according to claim 1 or 2. The space formed by the fuel reservoir has a tapered shape that decreases in diameter toward the downstream side along the axial direction of the needle.
The fuel-injection nozzle of any one of Claims 1-3.