JP2018003789A - Fuel injection valve and common rail injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a fuel injection valve capable of performing a boot type injection.SOLUTION: A fuel injection valve 1 comprises a main body part 10 having a fuel injection hole 15 formed at one end and a fuel supply flow passage 30 for supplying fuel to the fuel injection hole 15; and a needle valve 61 movably stored in the main body part 10 and shutting off a communication between the fuel injection hole 15 and the fuel supply flow passage 30 under a state in which it is sat at a seat part 16. In addition, the main body part 10 has a throttle forming passage 33b between the fuel injection hole 15 and the fuel supply flow passage 30. Then, under a state in which a distance between the needle valve 61 and the seat part 16 is less than a specified distance, a throttle part 80 is formed between an inner peripheral surface 82 of the throttle forming passage 33b and an outer peripheral surface 81 of a lower end part 61a of the needle valve 61 and under a state in which a distance between the needle valve 61 and the seat part 16 is more than a specified distance, the lower end part 61a of the needle valve 61 can be pulled out of the throttle forming passage 33b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel injection valve (injector) that injects fuel into a combustion chamber of an engine, and a common rail injection system including the fuel injection valve.

  Conventionally, a common rail injection system is known as a system for injecting fuel into a combustion chamber such as a diesel engine (see Patent Document 1). This common rail injection system accumulates fuel in the common rail to increase the pressure, and supplies the fuel that has been increased to a certain pressure to the fuel supply flow path of the fuel injection valve.

  The fuel injection valve used in the above-described common rail injection system has a main body portion in which a fuel injection hole is formed at the lower end, which is the end portion on the side inserted into the combustion chamber. The main body portion is provided with a fuel supply passage that is connected to the common rail and supplies fuel to the fuel injection hole. A needle valve (needle valve) is housed inside the main body so as to be movable up and down. The needle valve blocks communication between the fuel injection hole and the fuel supply flow path when the needle valve is lowered and seated on the seat portion of the main body. When the needle valve is raised, the fuel injection hole communicates with the fuel supply channel, and fuel is injected from the fuel injection hole into the combustion chamber.

  The needle valve housed in the main body is subjected to pressure acting in the direction of lowering the needle valve and pressure acting in the direction of raising the needle valve by the fuel supplied to the main body. Yes. And the needle valve rises inside the main body by lowering the pressure acting in the direction of lowering the needle valve. That is, the needle valve has a so-called balance valve structure.

  For example, in the case of the fuel injection valve described in Patent Document 1, a pressure adjusting chamber into which the fuel supplied to the main body flows is formed above the needle valve (on the side opposite to the fuel injection hole side). Due to the fuel supplied to the pressure adjusting chamber, a pressure for lowering the needle valve acts on the needle valve. The needle valve is also given a force to lower the needle valve by a spring disposed above the needle valve. On the other hand, a step portion whose lower side is narrowed is formed in a substantially central portion of the needle valve, and a fuel reservoir chamber into which fuel supplied to the main body portion flows is formed around the step portion. The fuel supplied to the fuel reservoir chamber acts on the needle valve with a pressure that raises the needle valve.

  When the force applied to the needle valve by the fuel and spring supplied to the pressure adjustment chamber exceeds the force applied to the needle valve by the fuel supplied to the fuel reservoir chamber, the needle valve is lowered. The communication between the fuel injection hole and the fuel supply channel is blocked, and the fuel is not injected from the fuel injection hole. Further, the force applied to the needle valve by the fuel supplied to the fuel reservoir chamber is reduced by reducing the pressure of the fuel in the pressure adjustment chamber, and the force applied to the needle valve by the fuel and spring supplied to the pressure adjustment chamber. If it exceeds the upper limit, the needle valve rises to connect the fuel injection hole and the fuel supply flow path, and fuel is injected from the fuel injection hole into the combustion chamber.

  The pressure adjustment of the fuel in the pressure adjustment chamber is performed by opening / closing an opening / closing device using an electromagnetic valve or the like. Specifically, the pressure adjustment chamber is connected to a first orifice passage (throttle portion) that allows the fuel supplied to the main body portion to flow into the pressure adjustment chamber. The pressure regulation chamber is also connected to a second orifice passage (throttle portion) that allows fuel to flow out from the pressure regulation chamber. The second orifice passage has a larger channel cross-sectional area than the first orifice passage. The opening / closing device opens and closes the flow path of the second orifice passage. Since the second orifice passage has a larger flow passage cross-sectional area than the first orifice passage, the pressure of the fuel in the pressure adjustment chamber is reduced by opening the flow passage of the second orifice passage by the opening / closing device. As a result, the needle valve rises to connect the fuel injection hole and the fuel supply channel, and fuel is injected from the fuel injection hole into the combustion chamber. Further, by closing the flow path of the second orifice passage by the opening / closing device, the pressure adjustment chamber rises to the same pressure as the pressure of the fuel reservoir chamber. As a result, the needle valve is lowered to cut off the communication between the fuel injection hole and the fuel supply flow path, and the fuel is not injected from the fuel injection hole.

Japanese Patent Laid-Open No. 10-82356

FIG. 5 is a diagram illustrating an example of boot-type injection. In addition, the continuous line shown in FIG. 5 has shown boot type injection.
As a method of injecting fuel from the fuel injection valve, an injection method called so-called boot type injection has been proposed. In the boot-type injection, first, a slight amount of fuel is continuously injected into the combustion chamber to form a slow combustion, thereby reducing combustion noise and NOx emission (A in FIG. 5). Thereafter, by increasing the fuel injection rate (fuel injection amount per unit time) to promote combustion, the effect of reducing the fuel consumption rate can be obtained (B in FIG. 5).

  However, the conventional fuel injection valve cannot stop the needle valve in the middle of its rise, and moves to the upper end when the pressure in the pressure adjustment chamber is reduced. For this reason, the conventional fuel injection valve can only maintain the fuel injection rate at the time of main injection when trying to continuously inject fuel into the combustion chamber. That is, the conventional fuel injection valve cannot continue to inject a minute amount of fuel into the combustion chamber before the main injection. Therefore, the conventional fuel injection valve performs the pilot injection one or more times (C in FIG. 5) to inject a small amount of fuel by shortening the opening time of the on-off valve before the main injection (C in FIG. 5). I could only imitate. That is, the conventional fuel injection valve has a problem that it cannot perform boot type injection.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a fuel injection valve and a common rail injection system capable of performing boot-type injection.

  A fuel injection valve according to the present invention is movably accommodated in a main body having a fuel injection hole formed at one end, a fuel supply passage for supplying fuel to the fuel injection hole, and a main body, A needle valve that is seated on the seat portion of the main body portion and blocks communication between the fuel injection hole and the fuel supply flow path, and the main body portion has a throttle forming path between the fuel injection hole and the fuel supply flow path. And when the distance between the needle valve and the seat portion is less than a specified distance, a throttle forming end that is an end of the needle valve on the fuel injection hole side is inserted into the throttle forming path, A throttle part is formed between the inner peripheral surface of the throttle forming path of the main body part and the outer peripheral surface of the throttle forming end part, and the distance between the needle valve and the seat part is not less than the specified distance. , The diaphragm forming end that formed the diaphragm section It is intended to exit from the aperture forming path not make.

  Here, the needle valve of the fuel injection valve according to the present invention may have a so-called balance valve structure. That is, in the present invention, the pressure applied to the needle valve by the fuel supplied to the main body portion to move the needle valve toward the seat portion and the pressure to move the needle valve away from the seat portion are applied. The needle valve may be separated from the seat portion within the main body portion by reducing the pressure that moves the needle valve toward the seat portion.

  Further, the fuel injection rate at the time of minute fuel injection performed before the main injection may be adjusted by the shape of the throttle forming passage of the main body and the shape of the throttle forming end of the needle valve. For example, the aperture forming path of the main body may be configured so that the inner peripheral surface forms a cylindrical space, and the aperture forming end may be formed in a cylindrical shape. Alternatively, for example, the throttle forming path of the main body may be configured so that the inner peripheral surface forms a cylindrical space, and the throttle forming end may be formed in a conical shape whose diameter decreases toward the fuel injection hole. Good. Further, for example, the throttle forming path of the main body is configured so that the inner peripheral surface forms a cylindrical space, and the throttle forming end portion has a conical portion whose diameter decreases toward the fuel injection hole, and the conical portion. And a cylindrical portion provided at the end of the portion on the fuel injection hole side. Further, for example, a flat portion may be formed on the outer peripheral surface of the aperture forming portion.

  Further, the common rail injection system according to the present invention is connected to the fuel injection valve according to the present invention and a fuel supply flow path of the fuel injection valve, and accumulates fuel to increase the pressure, and the fuel that has increased the pressure. And a common rail that supplies fuel to the fuel injection valve.

  In the fuel injection valve according to the present invention, when the distance between the needle valve and the seat portion is less than the specified distance, the fuel of the needle valve inserted in the throttle forming passage and the throttle forming passage of the main body portion A throttle portion is formed between the outer peripheral surface of the injection hole side end portion. In this state, since the fuel supplied to the fuel injection hole is limited by the throttle portion, a very small amount of fuel can be continuously injected into the combustion chamber. In the fuel injection valve according to the present invention, when the distance between the needle valve and the seat portion is equal to or greater than the specified distance, the end portion on the fuel injection hole side of the needle valve forming the throttle portion forms the throttle portion. The main body part exits from the throttle forming path. For this reason, the fuel supplied to the fuel injection hole is not limited, and the amount of fuel injected from the fuel injection hole can be increased. That is, the fuel injection valve according to the present invention can perform boot-type injection when the needle valve moves in one direction, in other words, when the needle valve makes one stroke.

  In addition, since the fuel injection valve according to the present invention can perform boot-type injection when the needle valve moves in one direction, the boot-type injection can be performed even if the needle valve has a balance valve structure.

  The fuel injection valve according to the present invention is a boot-type injection when the needle valve moves in one direction by appropriately setting the shape of the throttle forming passage of the main body and the shape of the throttle forming end of the needle valve. The fuel injection shape suitable for the engine provided with the fuel injection valve can be obtained.

  In addition, since the fuel injection valve according to the present invention can perform boot-type injection when the needle valve moves in one direction, the fuel injection valve according to the present invention relates to a common rail injection system that supplies fuel at a constant pressure to the fuel injection valve. Even if a fuel injection valve is employed, boot-type injection can be performed.

It is a figure which shows the common rail injection system which concerns on Embodiment 1 of this invention. FIG. 2 is a detailed view of a Q part in FIG. 1. It is explanatory drawing for demonstrating operation | movement of the fuel injection valve which concerns on Embodiment 1 of this invention. It is explanatory drawing for demonstrating operation | movement of the fuel injection valve which concerns on Embodiment 1 of this invention. It is a figure which shows an example of boot type injection. It is a principal part enlarged view which shows an example of the fuel injection valve which concerns on Embodiment 2 of this invention. It is explanatory drawing for demonstrating operation | movement of the fuel injection valve shown in FIG. It is explanatory drawing for demonstrating operation | movement of the fuel injection valve shown in FIG. It is a figure which shows the shape of boot type injection of the fuel injection valve shown in FIG. It is a principal part enlarged view which shows another example of the fuel injection valve which concerns on Embodiment 2 of this invention. It is explanatory drawing for demonstrating operation | movement of the fuel injection valve shown in FIG. It is explanatory drawing for demonstrating operation | movement of the fuel injection valve shown in FIG. It is a figure which shows the shape of boot type injection of the fuel injection valve shown in FIG. It is a principal part enlarged view which shows another example of the fuel injection valve which concerns on Embodiment 2 of this invention. It is ZZ sectional drawing of FIG. It is a figure which shows the shape of boot type injection of the fuel injection valve shown in FIG.

Embodiments relating to the fuel injection valve and the common rail injection system of the present invention will be specifically described below. However, the following embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In the following embodiments, the end portion side where the fuel injection hole is formed is the lower side of the fuel injection valve, and the end portion side opposite to the end portion on the fuel injection hole side is the upper side of the fuel injection valve. The fuel injection valve will be described as follows.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a common rail injection system according to Embodiment 1 of the present invention.
A common rail injection system 100 according to the first embodiment includes a fuel injection valve 1 that injects fuel into a combustion chamber of a diesel engine or the like, and fuel that accumulates the fuel to increase the pressure and inject the fuel that has increased in pressure. And a common rail 4 to be supplied to the valve 1.

  The main body 10 of the fuel injection valve 1 has a fuel injection hole 15 formed at the lower end. Further, the main body 10 includes a fuel supply passage 30 that supplies fuel injected from the fuel injection holes 15 to the fuel injection holes 15. The main body 10 also includes a fuel discharge passage 40 that discharges excess fuel supplied to the main body 10 to the outside.

  The main body 10 according to the first embodiment includes an injector housing 11, a nozzle body 14, a nozzle nut 17, a valve body 19, and a holder 20. In addition, these components which comprise the main-body part 10 are an example to the last. Depending on the design of the fuel injection valve 1, the number of divisions of the main body 10 can be arbitrarily changed in other words.

  Specifically, the injector housing 11 is formed with a through hole 12 penetrating in the vertical direction. The valve piston 63 is accommodated in the through hole 12 so as to be movable in the vertical direction. A spring chamber 13 is also formed in a part of the through hole 12. The spring chamber 13 houses a nozzle spring 64 that urges the needle valve 61 downward. A fuel passage 31 is also formed in the injector housing 11. The fuel passage 31 has a lower end that opens to the lower end of the injector housing 11 and an upper end that opens to the side surface of the injector housing 11. A fuel supply connection port 51 is connected to the upper end of the fuel passage 31 so as to communicate with the fuel passage 31. The fuel supply connection port 51 is connected to the common rail 4. That is, the fuel supplied from the fuel tank 2 to the common rail 4 by the supply pump 3 is accumulated in the common rail 4 to become high-pressure fuel, and is supplied to the fuel injection valve 1 through the fuel supply connection port 51.

  A nozzle body 14 is attached to the lower end side of the injector housing 11 by a nozzle nut 17. The nozzle body 14 is formed with a hole 33 that is recessed downward from the upper end. The hole 33 is arranged coaxially with the through hole 12 of the injector housing 11. A needle valve 61 is accommodated in the hole 33 so as to be movable in the vertical direction. The upper end of the needle valve 61 is in contact with the lower end of the valve piston 63. Further, the vicinity of the lower end portion of the hole 33 is the seat portion 16 of the needle valve 61. Below the hole 33, for example, a plurality of fuel injection holes 15 are formed so as to communicate the hole 33 and the outside of the nozzle body 14. In addition, a fuel reservoir chamber 33 a is formed in a part of the hole 33 at a position facing the pressure receiving portion 62 of the needle valve 61. One end of a fuel passage 32 communicates with the fuel reservoir 33a. The other end of the fuel passage 32 communicates with the fuel passage 31 of the injector housing 11.

  That is, in the first embodiment, the fuel supply passage 30 for supplying fuel from the fuel supply connection port 51 to the fuel injection hole 15 includes the fuel passage 31, the fuel passage 32, the fuel reservoir chamber 33a, the hole 33, and the needle. It is comprised by the clearance gap between the valves 61. FIG. Then, when the needle valve 61 is seated (seat) on the seat portion 16 connected to the fuel injection hole 15, the communication between the fuel supply passage 30 (more specifically, the hole 33) and the fuel injection hole 15 is cut off, and fuel injection is performed. The hole 15 is closed. On the other hand, the fuel injection hole 15 is opened when the needle valve 61 is separated (lifted) from the seat portion 16. As a result, fuel injection can be started and stopped.

  A valve body 19 is attached to the upper end of the injector housing 11 so as to be inserted into the through hole 12. The valve body 19 is formed with a hole 18 that is recessed upward from the lower end. The hole 18 is arranged coaxially with the through hole 12 of the injector housing 11. The upper part of the valve piston 63 is inserted into the hole 18 so as to be slidable in the vertical direction. As a result, the portion of the hole 18 that is above the top 63 a of the valve piston 63 becomes the pressure control chamber 66.

  The valve body 19 also includes an opening / closing orifice passage 44 that communicates the pressure control chamber 66 and the upper end of the valve body 19, and an introduction-side orifice passage 43 that communicates the pressure control chamber 66 and the side surface of the valve body 19. Is formed. The injector housing 11 includes a pressure introduction chamber 42 formed at a position facing the introduction-side orifice passage 43, and a fuel passage 41 that communicates the pressure introduction chamber 42 with the fuel supply connection port 51. The opening / closing orifice passage 44 can be freely opened and closed by an opening / closing device 60 described later. That is, when the opening / closing orifice passage 44 is opened, the fuel supplied from the fuel supply connection port 51 to the pressure control chamber 66 through the fuel passage 41, the pressure introduction chamber 42 and the introduction-side orifice passage 43 is opened / closed. It is configured to flow out through the orifice passage 44 and above the valve body 19 (a low pressure chamber 45 described later). Here, in the first embodiment, the flow passage cross-sectional area of the opening / closing orifice passage 44 is larger than the flow passage cross-sectional area of the introduction-side orifice passage 43. For this reason, when the opening / closing orifice passage 44 is opened, the pressure in the pressure control chamber 66 becomes lower than the pressure of the fuel flowing into the main body 10 from the fuel supply connection port 51.

  A holder 20 is attached to the upper end of the injector housing 11. An electromagnetic valve 67 that is an opening / closing device 60 is accommodated in the holder 20. The space between the electromagnetic valve 67 and the valve body 19 is the above-described low pressure chamber 45. The low pressure chamber 45 communicates with the fuel discharge connection port 52 by a fuel passage (not shown) formed around the electromagnetic valve 67, for example. That is, in the first embodiment, the fuel discharge passage 40 for discharging the surplus fuel supplied to the main body 10 to the outside is the fuel passage 41, the pressure introduction chamber 42, the introduction-side orifice passage 43, and the pressure control chamber 66. The opening / closing orifice passage 44, the low pressure chamber 45, and a fuel passage (not shown) formed around the electromagnetic valve 67, for example. The fuel discharge connection port 52 is connected to the fuel tank 2. For this reason, the fuel that has flowed out of the main body 10 through the fuel discharge channel 40 is returned to the fuel tank 2 through the fuel discharge connection port 52.

  The electromagnetic valve 67 that is the opening / closing device 60 includes a coil 68, an armature 69, a valve body 70, and a valve spring 71. The coil 68 is connected to an energization connection port 53 provided at the upper end of the holder 20. When the coil 68 is energized from a power supply source (not shown) connected to the energization connection port 53 through the energization connection port 53, the armature 69 is resisted against the urging force of the valve spring 71. Sucked into. As a result, the valve body 70 provided at the lower end of the armature 69 is lifted from the valve seat surface of the opening / closing orifice passage 44 so that the pressure in the pressure control chamber 66 can be released to the low pressure chamber 45. By operating the valve body 70 in this way, the pressure of the pressure control chamber 66 is controlled, and the back pressure of the needle valve 61 is controlled via the valve piston 63, so that the seat on the seat portion 16 of the needle valve 61 and The lift can be controlled.

In the fuel injection valve 1 configured as described above, the high-pressure fuel from the common rail 4 acts on the pressure receiving portion 62 of the needle valve 61 in the fuel reservoir chamber 33a from the fuel supply connection port 51 through the fuel passages 31 and 32. At the same time, it also acts on the top 63 a (that is, the needle valve 61) of the valve piston 63 in the pressure control chamber 66 via the fuel passage 41 and the pressure introduction chamber 42.
Therefore, in a state where the pressure control chamber 66 is cut off from the low pressure chamber 45 side by the valve body 70, the needle valve 61 is caused by the back pressure of the pressure control chamber 66 received through the valve piston 63 and the urging force of the nozzle spring 64. The fuel injection hole 15 is closed by being seated on the seat portion 16 of the nozzle body 14.

  On the other hand, when the coil 68 is energized and the armature 69 is attracted to the coil 68 and the valve body 70 opens the opening / closing orifice passage 44, the high pressure in the pressure control chamber 66 is opened to the low pressure chamber 45 through the opening / closing orifice passage 44. Is done. Accordingly, the high pressure acting on the top 63 a of the valve piston 63 in the pressure control chamber 66 is released, and the needle valve 61 is seated against the urging force of the nozzle spring 64 by the high pressure acting on the pressure receiving portion 62. The fuel injection hole 15 is opened and fuel injection is performed.

  When the opening and closing orifice passage 44 is closed by the valve body 70 by stopping the energization of the coil 68, the pressure in the pressure control chamber 66 acts through the valve piston 63 and the nozzle spring 64 is applied. Due to the force, the needle valve 61 is seated on the seat portion 16 which is the seat position, the fuel injection hole 15 is closed, and fuel injection ends.

  That is, the needle valve 61 according to the first embodiment is separated from the seat portion 16 by the pressure that moves the needle valve 61 toward the seat portion 16 by the fuel supplied to the main body portion 10. Pressure to act. Then, the needle valve 61 moves away from the seat portion 16 by reducing the pressure that moves the needle valve 61 toward the seat portion 16. That is, the needle valve 61 according to the first embodiment has a so-called balance valve structure.

  Here, the fuel injection valve 1 according to the first embodiment has a lower end portion configured as follows in order to enable boot-type injection.

FIG. 2 is a detailed view of a portion Q in FIG.
The lower end 61a of the needle valve 61 is formed in a cylindrical shape, for example. In the nozzle body 14, a throttle forming path 33 b is formed between the hole 33 and the fuel injection hole 15, that is, between the fuel supply flow path 30 and the fuel injection hole 15. A cylindrical space, for example, is formed inside the inner peripheral surface 82 of the aperture forming path 33b. When the needle valve 61 is seated on the seat portion 16, the lower end portion 61a of the needle valve 61 is inserted into the throttle forming path 33b, and the inner peripheral surface 82 of the throttle forming path 33b and the needle valve 61 are The outer peripheral surface 81 of the lower end part 61a is opposed. In the first embodiment, a sack hole 15a for temporarily storing fuel to be injected from the fuel injection hole 15 is formed between the throttle forming path 33b and the fuel injection hole 15.

That is, a fuel supply passage for supplying fuel to the fuel injection hole 15 is provided between the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the inner peripheral surface 82 of the throttle forming passage 33 b formed in the nozzle body 14. Also works. In the first embodiment, the flow of the flow path formed between the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the inner peripheral surface 82 of the throttle forming path 33 b formed in the nozzle body 14. The road cross-sectional area is made smaller than the flow path cross-sectional area of the fuel supply flow path 30 in other ranges. That is, the throttle portion 80 is formed between the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the inner peripheral surface 82 of the throttle formation path 33 b formed in the nozzle body 14. Further, the length of the throttle portion 80 in a state where the needle valve 61 is seated on the seat portion 16 is smaller than the lift amount (vertical movement amount) of the needle valve 61.
Here, the lower end portion 61a of the needle valve 61 corresponds to the throttle forming end portion of the present invention. In the first embodiment, the lower end of the needle valve 61 (the portion formed below the lower end portion 61a) is formed in a conical shape, but the conical portion is a needle that forms the throttle portion 80. The lower end 61a of the valve 61 is not included.

  By forming the throttle portion 80 described above, the fuel injection valve 1 according to Embodiment 1 allows the needle valve 61 to perform one stroke (one stroke) when the needle valve 61 moves in one direction from the lower end to the upper end. When moving up and down), fuel is injected from the fuel injection hole 15 as follows.

  3 and 4 are explanatory diagrams for explaining the operation of the fuel injection valve according to Embodiment 1 of the present invention. 3 and 4 show the same part (Q portion in FIG. 1) as FIG. 2, and shows how the needle valve 61 rises from the state of FIG. Hereinafter, the fuel injection operation from the fuel injection hole 15 of the fuel injection valve 1 according to the first embodiment will be described with reference to FIGS.

  When the pressure control chamber 66 is shut off from the low pressure chamber 45 side by the valve body 70 of the electromagnetic valve 67, when the valve body 70 opens the opening / closing orifice passage 44 by energizing the coil 68 of the electromagnetic valve 67, the pressure control is performed. The pressure in the chamber 66 decreases. Thereby, from the state of FIG. 2 in which the needle valve 61 is seated on the seat portion 16, the needle valve 61 rises in the direction of the white arrow, and the state of FIG. 3 is obtained. As shown in FIG. 3, when the distance between the needle valve 61 and the seat portion 16 is less than the specified distance, the lower end portion 61 a of the needle valve 61 is inserted into the throttle forming path 33 b formed in the nozzle body 14. It is in the state. That is, the throttle portion 80 is formed between the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the inner peripheral surface 82 of the throttle formation path 33 b formed in the nozzle body 14. For this reason, in the state where the distance between the needle valve 61 and the seat portion 16 is less than the specified distance, the fuel supplied to the fuel injection hole 15 is restricted by the throttle portion 80. Therefore, as shown by A in FIG. 5, a minute amount of fuel can be continuously injected into the combustion chamber from the fuel injection hole 15.

  The fuel injection rate (fuel injection amount per unit time) from the fuel injection hole 15 is determined based on the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the inner periphery of the throttle forming path 33 b formed in the nozzle body 14. The amount of clearance between the surface 82 can be adjusted. In addition, the time during which a small amount of fuel is continuously injected into the combustion chamber is adjusted by adjusting at least one of the vertical length of the outer peripheral surface 81 and the vertical length of the inner peripheral surface 82, and the throttle portion 80 is formed. It can be adjusted by adjusting the time.

  When the needle valve 61 further rises in the direction of the white arrow from the state of FIG. 3, the state of FIG. 4 is obtained. As shown in FIG. 4, when the distance between the needle valve 61 and the seat portion 16 is equal to or greater than the specified distance, the lower end portion 61 a of the needle valve 61 forming the throttle portion 80 forms the throttle portion 80. Exit from the aperture forming path 33b. That is, the throttle portion 80 is not formed between the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the inner peripheral surface 82 of the throttle formation path 33 b formed in the nozzle body 14. For this reason, the fuel supplied to the fuel injection hole 15 is not restricted. Therefore, as shown by B in FIG. 5, the amount of fuel injected from the fuel injection hole 15 can be increased and main injection can be performed. In the first embodiment, when the needle valve 61 is raised by, for example, 0.1 [mm] from the state in which the needle valve 61 is seated on the seat portion 16, the needle valve 61 forming the throttle portion 80 is formed. The lower end portion 61a of the lens is configured to be removed from the aperture forming path 33b that formed the aperture 80.

  As described above, since the fuel injection valve 1 according to the first embodiment includes the throttle portion 80 as described above, when the needle valve 61 moves from the lower end to the upper end, in other words, the needle valve 61 has one stroke ( Boot-type injection can be performed during a single vertical movement.

  Further, since the fuel injection valve 1 according to Embodiment 1 can perform the boot type injection when the needle valve 61 moves from the lower end to the upper end, the boot type injection can be performed even if the needle valve 61 has a balance valve structure. It can be performed. In addition, the needle valve 61 is provided with the above-described restrictor 80 even in a structure other than the balance valve structure (for example, a structure in which the needle valve 61 is connected to an armature and the needle valve 61 is directly driven by an electromagnetic valve or the like). Boot-type injection can be performed when the valve 61 moves from the lower end to the upper end.

  Further, since the fuel injection valve 1 according to the first embodiment can perform boot-type injection when the needle valve 61 moves from the lower end to the upper end, the common rail that supplies fuel at a constant pressure to the fuel injection valve 1. Even if the fuel injection valve 1 according to the first embodiment is employed in the injection system 100, boot-type injection can be performed.

  In the first embodiment, the opening / closing device 60 using the electromagnetic valve 67 is employed. However, the present invention can be implemented even when an opening / closing device having another configuration (for example, an opening / closing device using a piezo element) is employed. Can do. Further, although the sack hole 15a is provided in the first embodiment, the present invention can also be implemented in a fuel injection valve not provided with the sack hole 15a.

Embodiment 2. FIG.
In the first embodiment, the throttle forming path 33b is formed in the nozzle body 14 so that the inner peripheral surface 82 forms a cylindrical space. Moreover, the lower end part 61a of the needle valve 61 was formed in a cylindrical shape. However, the shapes of the throttle forming path 33b of the nozzle body 14 and the lower end portion 61a of the needle valve 61 are not limited to the shapes shown in the first embodiment. By appropriately setting the shape of the throttle forming path 33b of the nozzle body 14 and the lower end portion 61a of the needle valve 61, the fuel injection valve 1 provides the shape of the boot type injection when the needle valve 61 moves from the lower end to the upper end. The fuel injection shape suitable for the engine to be used can be obtained. For this reason, below, an example of the shape of the throttle forming path 33b of the nozzle body 14 and the lower end portion 61a of the needle valve 61 will be described. In the second embodiment, items that are not particularly described are the same as those in the first embodiment, and the same functions and configurations are described using the same reference numerals.

FIG. 6 is an enlarged view of a main part showing an example of a fuel injection valve according to Embodiment 2 of the present invention. 7 and 8 are explanatory diagrams for explaining the operation of the fuel injection valve shown in FIG. FIG. 9 is a view showing the shape of the boot type injection of the fuel injection valve shown in FIG.
6 to 8 are longitudinal sectional views showing the vicinity of the lower end of the fuel injection valve 1, and show the position corresponding to the Q portion in FIG. Further, in FIG. 9, the shape of the boot type injection of the fuel injection valve 1 shown in the first embodiment is indicated by a one-dot chain line.

  In the fuel injection valve 1 shown in FIG. 6, the lower end portion 61a of the needle valve 61 is formed in a conical shape whose diameter decreases as it goes downward (that is, toward the fuel injection hole 15). Other configurations are the same as those in the first embodiment.

  In the fuel injection valve 1 configured as described above, as the needle valve 61 rises in the direction of the white arrow in the order of FIGS. 6, 7, and 8, the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 The flow passage cross-sectional area between the nozzle body 14 and the inner peripheral surface 82 of the throttle forming passage 33b gradually increases. For this reason, as shown by D in FIG. 9, the lower end portion 61 a of the needle valve 61 is inserted into the throttle forming path 33 b of the nozzle body 14, and the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the nozzle body 14 In a state where the throttle portion 80 is formed between the inner peripheral surface 82 of the throttle forming path 33b, that is, in a state where a small amount of fuel is injected into the combustion chamber, the fuel injection rate is gradually increased. I can go. In the fuel injection valve 1 shown in FIG. 6, the state of main injection after the lower end portion 61a of the needle valve 61 has escaped from the throttle forming path 33b of the nozzle body 14 is the same as in the first embodiment.

FIG. 10 is an enlarged view of a main part showing another example of the fuel injection valve according to Embodiment 2 of the present invention. 11 and 12 are explanatory diagrams for explaining the operation of the fuel injection valve shown in FIG. FIG. 13 is a view showing the shape of the boot type injection of the fuel injection valve shown in FIG.
10 to 12 are longitudinal sectional views showing the vicinity of the lower end of the fuel injection valve 1, and show the position corresponding to the Q portion in FIG. Moreover, in FIG. 13, the shape of the boot type injection of the fuel injection valve 1 shown in Embodiment 1 is shown with a dashed-dotted line.

  In the fuel injection valve 1 shown in FIG. 10, the lower end portion 61a of the needle valve 61 has a conical portion 61a1 and a cylindrical portion 61a2. The conical portion 61a1 is formed in a conical shape whose diameter decreases toward the lower side (that is, toward the fuel injection hole 15). The cylindrical portion 61a2 has, for example, a cylindrical shape having the same diameter as the lower end portion of the conical portion 61a1, and is provided at the lower end portion of the conical portion 61a1. Other configurations are the same as those in the first embodiment.

  In the fuel injection valve 1 configured as described above, the gap between the outer peripheral surface 811 of the conical portion 61a1 and the inner peripheral surface 82 of the throttle forming path 33b is the gap between the outer peripheral surface 812 of the cylindrical portion 61a2 and the throttle forming path 33b. It becomes below the clearance gap between the internal peripheral surfaces 82. For this reason, when the needle valve 61 is raised in the direction of the white arrow, in the state where the conical portion 61a1 is inserted into the throttle forming path 33b of the nozzle body 14, as shown in FIG. The amount of fuel flowing through is proportional to the amount of gap between the outer peripheral surface 811 of the conical portion 61a1 and the inner peripheral surface 82 of the throttle forming path 33b. Further, when the needle valve 61 rises in the direction of the white arrow, the conical portion 61a1 comes out of the throttle forming path 33b of the nozzle body 14 and the cylindrical portion 61a2 is inserted into the throttle forming path 33b. As shown in FIG. 12, the amount of fuel flowing through the throttle portion 80 is proportional to the gap amount between the outer peripheral surface 812 of the cylindrical portion 61a2 and the inner peripheral surface 82 of the throttle forming path 33b.

  Therefore, when the needle valve 61 rises in the direction of the white arrow, the outer peripheral surface 811 of the conical part 61a1 and the constriction forming path in a state where the conical part 61a1 is inserted into the constriction forming path 33b of the nozzle body 14. The clearance between the inner peripheral surface 82 of 33b gradually increases. For this reason, as shown by E in FIG. 13, the fuel injection rate can be gradually increased. Further, when the needle valve 61 rises in the direction of the white arrow, the conical portion 61a1 comes out of the throttle forming path 33b of the nozzle body 14 and the cylindrical portion 61a2 is inserted into the throttle forming path 33b. The gap between the outer peripheral surface 812 of the cylindrical portion 61a2 and the inner peripheral surface 82 of the aperture forming path 33b is constant. For this reason, as shown by F of FIG. 13, the fuel injection rate can be made constant. In the fuel injection valve 1 shown in FIG. 10, the state of the main injection after the lower end portion 61a of the needle valve 61 has escaped from the throttle forming path 33b of the nozzle body 14 is the same as in the first embodiment.

FIG. 14 is an enlarged view of a main part showing still another example of the fuel injection valve according to Embodiment 2 of the present invention. FIG. 15 is a ZZ cross-sectional view of FIG. FIG. 16 is a view showing the shape of the boot type injection of the fuel injection valve shown in FIG.
FIG. 14 is a longitudinal sectional view showing the vicinity of the lower end of the fuel injection valve 1 and shows a position corresponding to the Q portion of FIG. Further, in FIG. 16, the shape of the boot type injection of the fuel injection valve 1 shown in the first embodiment is indicated by a one-dot chain line.

  In the fuel injection valve 1 shown in FIG. 14, a flat portion 61 b is formed on the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61. Other configurations are the same as those in the first embodiment.

  In the fuel injection valve 1 configured as described above, the flow passage cross-sectional area between the outer peripheral surface 81 of the lower end portion 61a of the needle valve 61 and the inner peripheral surface 82 of the throttle forming passage 33b of the nozzle body 14 is flat. It increases compared with the case where 61b is not formed. Accordingly, as indicated by G in FIG. 16, the lower end portion 61 a of the needle valve 61 is inserted into the throttle forming passage 33 b of the nozzle body 14, and the outer peripheral surface 81 of the lower end portion 61 a of the needle valve 61 and the throttle of the nozzle body 14. In the state where the throttle portion 80 is formed between the inner circumferential surface 82 of the formation path 33b, that is, in the state where a small amount of fuel is injected into the combustion chamber, the flat portion 61b is not formed. In comparison, the fuel injection rate can be increased. In the fuel injection valve 1 shown in FIG. 14, the state of the main injection after the lower end portion 61 a of the needle valve 61 has escaped from the throttle forming path 33 b of the nozzle body 14 is the same as in the first embodiment. In addition, the flat part 61b may be formed in the fuel injection valve 1 shown in FIG. 6 or FIG. 10, and the fuel injection rate at the time of injecting a very small amount of fuel into a combustion chamber may be increased.

DESCRIPTION OF SYMBOLS 1 Fuel injection valve, 2 Fuel tank, 3 Supply pump, 4 Common rail, 10 Main part, 11 Injector housing, 12 Through hole, 13 Spring chamber, 14 Nozzle body, 15 Fuel injection hole, 15a Suck hole, 16 Seat part, 17 Nozzle nut, 18 holes, 19 valve body, 20 holder, 30 fuel supply passage, 31 fuel passage, 32 fuel passage, 33 holes, 33a fuel reservoir chamber, 33b throttle formation passage, 40 fuel discharge passage, 41 fuel passage, 42 Pressure introduction chamber, 43 Introduction side orifice passage, 44 Opening / closing orifice passage, 45 Low pressure chamber, 51 Fuel supply connection port, 52 Fuel discharge connection port, 53 Current connection port, 60 Opening / closing device, 61 Needle valve, 61a Lower end portion, 61a1 conical portion, 61a2 cylindrical portion, 61b flat portion, 62 pressure receiving portion, 63 valve piston 63a Top part, 64 Nozzle spring, 66 Pressure control chamber, 67 Solenoid valve, 68 Coil, 69 Armature, 70 Valve body, 71 Valve spring, 80 Throttle part, 81 Outer peripheral face, 811 Outer peripheral face, 812 Outer peripheral face, 82 Inner circumference Surface, 100 common rail injection system.

Claims (7)

A fuel injection hole formed at one end, and a main body having a fuel supply channel for supplying fuel to the fuel injection hole;
A needle valve that is movably housed inside the main body, sits on a seat portion of the main body, and blocks communication between the fuel injection hole and the fuel supply channel;
With
The main body has a throttle forming path between the fuel injection hole and the fuel supply channel,
In a state where the distance between the needle valve and the seat portion is less than a specified distance, a throttle forming end that is an end of the needle valve on the fuel injection hole side is inserted into the throttle forming path, Forming a throttle part between the inner peripheral surface of the throttle forming path and the outer peripheral surface of the throttle forming end;
In a state where the distance between the needle valve and the seat portion is equal to or greater than the specified distance, the throttle forming end portion that has formed the throttle portion is removed from the throttle forming path that has formed the throttle portion. A fuel injection valve. The needle valve is subjected to a pressure that moves the needle valve toward the seat portion and a pressure that moves the needle valve away from the seat portion by the fuel supplied to the main body portion,
2. The fuel injection valve according to claim 1, wherein the needle valve is separated from the seat portion when a pressure for moving the needle valve toward the seat portion decreases. The inner peripheral surface of the diaphragm forming path forms a cylindrical space,
The fuel injection valve according to claim 1, wherein the throttle forming end is formed in a cylindrical shape. The inner peripheral surface of the diaphragm forming path forms a cylindrical space,
3. The fuel injection valve according to claim 1, wherein the throttle forming end is formed in a conical shape whose diameter decreases toward the fuel injection hole. 4. The inner peripheral surface of the diaphragm forming path forms a cylindrical space,
The throttle forming end portion includes a conical portion whose diameter decreases toward the fuel injection hole, and a cylindrical portion provided at an end portion of the conical portion on the fuel injection hole side. The fuel injection valve according to claim 1 or 2.   The fuel injection valve according to any one of claims 1 to 4, wherein a flat portion is formed on an outer peripheral surface of the throttle forming end portion. The fuel injection valve according to any one of claims 1 to 6,
A common rail connected to the fuel supply flow path of the fuel injection valve, storing fuel to increase the pressure, and supplying the fuel with the increased pressure to the fuel injection valve;
A common rail injection system characterized by comprising:

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