JP6202606B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve used in an accumulator fuel injection control device for an internal combustion engine.

  2. Description of the Related Art Conventionally, a fuel injection valve that is used in an accumulator fuel injection control device for an internal combustion engine and injects high-pressure fuel supplied from a common rail (accumulator) into a cylinder of the internal combustion engine is known. The fuel injection valve includes a housing, a valve body, a nozzle body, a valve needle, and a back pressure control unit.

  The fuel injection valve includes an inlet connector to which a high-pressure pipe whose other end is connected to a common rail is connected, and high-pressure fuel is introduced into the fuel injection valve through a fuel passage formed in the inlet connector. The introduced high-pressure fuel is supplied to the fuel injection hole provided in the nozzle body, and is also supplied to the pressure control chamber side of the back pressure control unit. The back pressure control unit adjusts the pressure in the pressure control chamber to move the valve needle forward and backward, and controls the fuel injection by opening and closing the fuel injection hole.

  Here, the fuel supplied to the pressure control chamber side is introduced into a pressure introduction chamber formed between the valve body and the housing via a fuel passage in the housing, and then an orifice formed in the valve body. It is introduced into the pressure introducing chamber through the passage. The orifice passage has a shape in which the passage area is widened toward the outer peripheral surface of the valve body so as not to obstruct the fuel flow.

  In such a fuel injection valve, if a hard foreign matter is mixed in the fuel, the valve seat surface of the control valve of the back pressure control unit may be eroded and a precise fuel injection control function may be lost. For this reason, there is a fuel injection valve configured to collect a foreign matter in high-pressure fuel introduced into the fuel injection valve by arranging a filter in the inlet connector (see Patent Document 1 or 2).

  However, there is a limit to the collection of foreign matter in the fuel, and it is not easy to completely remove the foreign matter. In order to suppress damage to the valve seat surface, various coatings are applied to the valve seat surface to improve wear resistance, but no fundamental solution has been achieved. In particular, erosion of the valve seat surface of the control valve of the back pressure control unit due to the foreign matter may be promoted by further increasing the fuel pressure in order to comply with recent severe exhaust gas regulations.

JP 2006-105092 A FIG. JP 2009-203843 A

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress damage to the valve seat surface of the control valve of the back pressure control unit due to foreign matter in the high-pressure fuel.

  According to the present invention, the injector housing, the valve needle provided in the injector housing so as to be movable back and forth, and the rear end side of the injector housing are fitted and inserted into the rear end side of the valve needle. A fuel injection valve comprising: a valve body in which a pressure control chamber for storing pressure is formed; and a control valve for adjusting the pressure in the pressure control chamber. An annular pressure introducing chamber is formed, the injector housing is provided with a fuel passage for introducing fuel into the pressure introducing chamber, and the valve body is an orifice for connecting the pressure introducing chamber and the pressure control chamber The fuel passage includes a fuel that is introduced into the pressure introduction chamber in a certain direction around the outer periphery of the valve body. The orifice passage is provided at a position close to the most downstream when the connection position of the fuel passage in the pressure introducing chamber is the uppermost stream of the swirl flow. A fuel injection valve is provided to solve the above-mentioned problems.

  In the fuel injection valve of the present invention, it is preferable that the fuel passage is provided along a tangential direction of the pressure introducing chamber.

  In the fuel injection valve of the present invention, the orifice passage is provided at a position where the phase angle θ1 along the rotational direction of the swirl flow is 270 ° ≦ θ1 <360 ° when the connection position of the fuel passage is 0 °. It is preferable.

  Further, in the fuel injection valve of the present invention, the orifice passage is located on the outer peripheral surface side of the valve body and is located on the pressure control chamber side, and a tapered portion in which the passage area decreases toward the inside of the valve body. An angle θ2 formed by a surface located on the upstream side of the swirl flow in the inner peripheral surface of the tapered portion and the outer peripheral surface of the valve body. Is preferably smaller than an angle θ3 formed by a surface positioned on the downstream side of the swirling flow and the outer peripheral surface of the valve body.

  In the fuel injection valve of the present invention, it is preferable that the angle θ2 is set to a value of 90 ° or less.

  According to the fuel injection valve of the present invention, foreign matter in the high-pressure fuel that reaches the fuel injection valve can be prevented from reaching the back pressure control unit, and damage to the valve seat surface of the control valve can be reduced. Will be able to.

It is a figure shown in order to demonstrate the whole structure of the pressure accumulation type fuel-injection control apparatus provided with the fuel-injection valve concerning this Embodiment. It is a figure shown in order to demonstrate the positional relationship of a fuel channel and an orifice channel. It is a figure shown in order to demonstrate another form of an orifice channel | path.

Hereinafter, embodiments relating to the fuel injection valve of the present invention will be specifically described. However, this 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 addition, about each thing which attached | subjected the same code | symbol in each figure, the same member is shown unless there is particular description.

FIG. 1 is a diagram schematically illustrating an example of an overall configuration of a pressure accumulation fuel injection control device including a fuel injection valve 1 according to the present embodiment. In FIG. 1, the fuel injection valve 1 is shown as a cross-sectional view.
The accumulator fuel injection control device includes a supply pump 52 that pumps fuel from a fuel tank 51, a common rail 12 that stores high-pressure fuel pumped by the supply pump 52, and high-pressure fuel accumulated in the common rail 12 as an internal combustion engine. A fuel injection valve 1 that injects into a cylinder of an engine (not shown) is a main component. The overall configuration of the pressure accumulation type fuel injection control device is basically the same as that of a conventionally known pressure accumulation type fuel injection control device.

  Among these, the fuel injection valve 1 includes an injector housing 2, a nozzle body 3, a valve needle 4, a valve piston 5, a valve body 6, a back pressure control unit 7, and an inlet unit 8 as main components. It is configured.

  The nozzle body 3 is fastened to the tip end portion (lower end side in FIG. 1) of the injector housing 2 by a nozzle nut 9. The injector housing 2 and the nozzle body 3 are formed with first fuel passages 11 a and 11 b for sending the high-pressure fuel introduced from the inlet portion 8 to the fuel reservoir chamber 14 of the nozzle body 3. Further, the injector housing 2 is formed with a second fuel passage 13 for sending the fuel introduced from the inlet portion 8 to the pressure control chamber 19 of the back pressure control portion 7. The inlet portion 8 is provided with an inlet connector 30 that is liquid-tightly mounted in the connector insertion hole 8A. A high-pressure fuel pipe connected to the common rail 12 is connected to the inlet connector 30.

  In addition, a fuel reservoir chamber 14 is formed in the nozzle body 3 at a portion facing the pressure receiving portion 4 </ b> A of the valve needle 4. A fuel injection hole 16 is formed at the tip of the nozzle body 3, and the fuel injection hole 16 is formed by seating (seat) the tip of the valve needle 4 on a seat portion 17 connected to the fuel injection hole 16. On the other hand, the fuel injection hole 16 is opened when the valve needle 4 is separated (lifted) from the seat portion 17. As a result, fuel injection can be started and stopped.

  Further, a spring chamber 22 is formed around the central axis in the injector housing 2 to which the nozzle body 3 is fastened, and a nozzle spring 18 for biasing the valve needle 4 toward the seat portion 17. Is arranged. Further, the valve piston 5 is inserted into the hole 2A formed in the injector housing 2 and is slidably inserted into the sliding hole 6A formed in the valve body 6 so as to be located above the valve needle 4. It arrange | positions so that it may be located.

  Further, the valve body 6 is formed with a pressure control chamber 19 at a position where the top 5A of the valve piston 5 is located, and the top 5A of the valve piston 5 faces from the lower side (fuel injection hole 16 side). ing. The pressure control chamber 19 communicates with an introduction-side orifice passage 20 formed in the valve body 6. The introduction-side orifice passage 20 is communicated with the second fuel passage 13 via a pressure introduction chamber 21 formed annularly in the circumferential direction of the valve body 6 between the valve body 6 and the injector housing 2. Thereby, the introduction pressure from the common rail 12 is supplied to the pressure control chamber 19 through the second fuel passage 13, the pressure introduction chamber 21, and the introduction-side orifice passage 20 in order.

  The pressure control chamber 19 also communicates with the opening / closing orifice passage 23, and the opening / closing orifice passage 23 can be opened and closed by operating a control valve 28 of the back pressure control unit 7 described later. The pressure receiving area of the top 5A of the valve piston 5 in the pressure control chamber 19 is set larger than the pressure receiving area of the pressure receiving part 4A of the nozzle needle 4.

  The back pressure control unit 7 includes a control valve 28, a holder 29, and a pressure control chamber 19 as main elements. The control valve 28 includes a magnet 25, an armature 27, and a control valve body 24. When a drive signal is supplied to the magnet 25 from the control circuit, the armature 27 is attracted to the magnet 25 against the urging force of the valve spring 26, and the control valve body 24 continues to the opening / closing orifice passage 23. Lifting from the surface allows the pressure in the pressure control chamber 19 to be released to the fuel return path 15. In this way, the pressure of the pressure control chamber 19 is controlled by operating the control valve body 24, and the back pressure of the valve needle 4 is controlled via the valve piston 5, whereby the seat to the seat portion 17 of the valve needle 4 is controlled. And the lift can be controlled.

In the fuel injection valve 1 configured as described above, the high pressure fuel from the common rail 12 acts on the pressure receiving portion 4A of the valve needle 4 in the fuel reservoir chamber 14 from the inlet portion 8 through the first fuel passages 11a and 11b. At the same time, it acts on the top 5A of the valve piston 5 in the pressure control chamber 19 via the second fuel passage 13 and the pressure introduction chamber 21.
Therefore, in a state where the pressure control chamber 19 is disconnected from the fuel low pressure side by the control valve body 24, the valve needle 4 is caused by the back pressure of the pressure control chamber 19 received through the valve piston 5 and the urging force of the nozzle spring 18. The fuel injection hole 16 is closed by being seated on the seat portion 17 of the nozzle body 3.

  On the other hand, when the armature 27 is attracted to the magnet 25 by supplying a drive signal to the magnet 25 at a predetermined timing, and the control valve body 24 opens the opening / closing orifice passage 23, the high pressure in the pressure control chamber 19 is changed to the opening / closing orifice. It returns to the fuel tank 51 through the fuel return path 15 via the passage 23. Therefore, the high pressure acting on the top portion 5A of the valve piston 5 in the pressure control chamber 19 is released, and the valve needle 4 resists the biasing force of the nozzle spring 18 by the high pressure acting on the pressure receiving portion 4A. The fuel injection hole 16 is opened and fuel injection is performed.

  When the opening / closing orifice passage 23 is closed by the control valve body 24 by demagnetizing the magnet 25, the valve needle 4 is moved via the valve piston 5 by the pressure in the pressure control chamber 19 and the urging force of the nozzle spring 18. The fuel injection hole 16 is closed by being seated on the seat portion 17 which is the seat position, and the fuel injection is completed.

Next, the mechanism by which high-pressure fuel is introduced into the pressure introduction chamber 19 will be described in detail with reference to FIGS.
2A shows an AA cross-sectional view of the fuel injection valve 1 shown in FIG. 1, and FIG. 2B shows a cross-sectional view in which the region of the pressure introducing chamber 21 is further enlarged. In the fuel injection valve 1 of the present embodiment, the second fuel passage 13 that connects the connector insertion hole 8A and the pressure introducing chamber 21 is provided in a direction that does not overlap the axis P of the fuel injection valve 1. In the example of FIGS. 2A and 2B, the second fuel passage 13 is disposed along the tangential direction of the pressure introducing chamber 21. As a result, the fuel introduced into the pressure introduction chamber 21 forms a swirling flow that flows in a certain direction around the outer periphery of the valve body 6 in the pressure introduction chamber 21.

  The valve body 6 is provided with an introduction-side orifice passage 20 that connects the pressure introduction chamber 21 and the pressure control chamber 19. The introduction-side orifice passage 20 includes a tapered portion 20a and a throttle portion 20b. The tapered portion 20 a is positioned on the outer peripheral surface side of the valve body 6 and is configured so that the passage area becomes smaller toward the inside of the valve body 6. The throttle portion 20b is located on the pressure control chamber 19 side and is provided continuously with the tapered portion 20a. The tapered portion 20 a is provided to facilitate introduction of high-pressure fuel from the pressure introduction chamber 21 to the pressure control chamber 19.

  In the fuel injection valve 1 of the present embodiment, the introduction-side orifice passage 20 is provided at a position close to the most downstream when the connection position of the second fuel passage 13 in the pressure introduction chamber 21 is defined as the most upstream flow of the swirl flow. It has been. Specifically, in the cross-sectional view of FIG. 2B, the position of the edge on the upstream side of the swirl flow among the edges of the opening of the second fuel passage 13 facing the pressure introduction chamber 21 is the most upstream position (phase = 0). And the introduction-side orifice passage 20 is provided so that 270 ° ≦ θ1 <360 °, where θ1 is the phase in the turning direction of the center line of the introduction-side orifice passage 20.

  Thus, when foreign matter is mixed in the high-pressure fuel introduced into the pressure introduction chamber 21, the high-pressure fuel flows while swirling in the pressure introduction chamber 21 and reaches the introduction-side orifice passage 20. The foreign matter is moved to the inner peripheral surface of the injector housing 2 by centrifugal force, so that it is difficult to reach the introduction-side orifice passage 20. The foreign matter pressed against the inner peripheral surface of the injector housing 2 falls to the nozzle 3 side by gravity (see FIG. 1). Accordingly, the foreign matter is hardly introduced into the pressure control chamber 19, and the foreign matter that reaches the valve seat surface of the control valve 28 through the opening / closing orifice passage 23 is reduced. As a result, damage to the valve seat surface can be reduced.

FIG. 3 shows a cross-sectional view of another embodiment of the fuel injection valve 1. The cross-sectional view of FIG. 3 corresponds to a part of the cross-sectional view of FIG.
In the example shown in FIG. 3, the angle θ2 formed by the surface located on the upstream side of the swirling flow and the outer peripheral surface of the valve body 6 in the inner peripheral surface of the tapered portion 20a of the introduction-side orifice passage 20A is the downstream of the swirling flow. The angle θ3 formed by the surface located on the side and the outer peripheral surface of the valve body 6 is made smaller. The angle θ2 at this time can be 90 ° or less. Thereby, the surface located on the upstream side is formed at an acute angle with respect to the direction in which the swirling flow flows, and the entry of foreign matter into the introduction-side orifice passage 20 can be further reduced.

1: fuel injection valve, 2: injector housing, 3: nozzle body, 4: valve needle, 5: valve piston, 6: valve body, 7: back pressure control section, 8: inlet section, 8A: connector insertion hole, 9 : Nozzle nut, 11a and 11b: first fuel passage, 12: common rail, 13: second fuel passage, 14: fuel reservoir, 15: fuel return passage, 16: fuel injection hole, 17: seat portion, 18: nozzle Spring: 19: Pressure control chamber, 20: Introduction side orifice passage, 20a: Tapered portion, 20b: Restriction portion, 21: Pressure introduction chamber, 22: Spring chamber, 23: Opening / closing orifice passage, 24: Valve ball, 25: Magnet: 26: Valve spring, 27: Armature, 28: Control valve, 29: Holder, 30: Inlet connector, 51: Fuel tank

Claims (4)

An injector housing, a valve needle provided in the injector housing so as to be movable back and forth, and a pressure needle that is inserted into a rear end side of the injector housing and stores a pressure applied to a rear end side of the valve needle therein. In a fuel injection valve comprising a valve body in which a pressure control chamber is formed, and a control valve for adjusting the pressure in the pressure control chamber,
An annular pressure introduction chamber surrounding the valve body is formed on the outer periphery of the valve body,
The injector housing includes a fuel passage for introducing fuel into the pressure introduction chamber;
The valve body has an orifice passage connecting the pressure introduction chamber and the pressure control chamber,
The fuel passage is provided so as to form a swirling flow in which the fuel introduced into the pressure introducing chamber flows in a constant direction around the outer periphery of the valve body, and the connection position of the fuel passage in the pressure introducing chamber is defined as the swirling flow. When the uppermost stream is provided , the orifice passage is provided at a position close to the most downstream ,
The orifice passage is formed on the outer peripheral surface side of the valve body and has a taper portion whose passage area decreases toward the inside of the valve body, and is formed continuously with the taper portion on the pressure control chamber side. An angle θ2 formed by a surface located on the upstream side of the swirling flow in the inner circumferential surface of the tapered portion and the outer circumferential surface of the valve body is located on the downstream side of the swirling flow. a fuel injection valve, wherein to Rukoto smaller than the angle θ3 formed between the surface and the outer peripheral surface of the valve body to be.   The fuel injection valve according to claim 1, wherein the fuel passage is provided along a tangential direction of the pressure introducing chamber. 3. The orifice passage is provided at a position where a phase angle θ1 along the rotational direction of the swirl flow is 270 ° ≦ θ1 <360 ° when the connection position of the fuel passage is 0 °. The fuel injection valve described in 1. The fuel injection valve according to any one of claims 1 to 3, wherein the angle θ2 is set to a value of 90 ° or less.

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