JP2014234764A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress damage of a valve seat portion of a control valve of a back pressure control section caused by foreign matters in high pressure fuel.SOLUTION: An inlet connector having an introduction passage of high pressure fuel is mounted to an inlet opening of a housing. A fuel chamber is formed by an end surface of the inlet connector and a bottom surface of the inlet opening. A first fuel passage communicating with the side of a nozzle is opened in an outer peripheral portion of the bottom surface in a region of the fuel chamber, and a second fuel passage communicating to the side of the back pressure control section is opened in a central portion, so that the high pressure fuel introduced from the inlet connector to the fuel chamber can form a turning flow.

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. This fuel injection valve is configured to include a housing, 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 control chamber side of the back pressure control unit. In the back pressure control unit, the pressure in the control chamber is adjusted to move the valve needle forward and backward, and the fuel injection is controlled by opening and closing the fuel injection hole.

  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).

Specifically, in the fuel injection valve described in Patent Document 1, an edge filter is press-fitted into an inlet connector, and foreign matter is collected using a gap formed thereby as a filter mesh.
Further, the fuel injection valve described in Patent Document 2 has a large number of holes formed in a portion of the filter main body portion formed in a bag shape that faces the inner wall surface of the inlet portion. Foreign matter is captured by the main body.

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

  However, the structure of the filter described in Patent Document 1 has a length in the axial direction of the inlet connector, and there is a possibility that foreign matter larger than the gap formed will pass through. Further, the filter described in Patent Document 2 has a limit in reducing the size of the hole to be formed, and it is difficult to collect foreign matter of several μm that reaches the fuel injection valve.

  In particular, in recent years, the performance of a fuel main filter provided at a location other than the fuel injection valve in an accumulator fuel injection control device has been improved, and foreign matter that reaches the fuel injection valve is caused by the gap in the filter structure of the fuel injection valve. However, it is difficult to collect foreign matters in the fuel with the conventional filter structures. Furthermore, further increase in fuel pressure to meet recent strict exhaust gas regulations may promote erosion of the valve seat surface of the control valve of the back pressure control unit due to the foreign matter.

  This invention is made | formed in view of such a problem, and makes it one of the objectives to suppress the damage to the valve-seat part of the control valve of the back pressure control part by the foreign material in a high pressure fuel.

  According to the present invention, a housing having a first fuel passage communicating with the fuel injection hole and a second fuel passage communicating with the pressure control chamber, a valve needle provided to move forward and backward in the housing, And a control valve that controls the opening and closing of the fuel injection hole by moving the valve needle forward and backward by adjusting the pressure, wherein the housing includes an inlet opening, and the inlet opening includes An inlet connector having a high-pressure fuel introduction passage is attached, a fuel chamber is formed by an end surface portion of the inlet connector and a bottom surface portion of the inlet opening, and an outer peripheral portion of the bottom surface portion in the region of the fuel chamber The first fuel passage is opened and the second fuel passage is opened at the center, and is introduced into the fuel chamber from the inlet connector. Fee is provided a fuel injection valve, characterized in that it is formed configured to be able to swirl flow, it is possible to solve the problems described above.

  Further, in the fuel injection valve of the present invention, the inlet connector is provided in the fuel chamber by being provided in an axial direction extending in the axial direction, extending in the circumferential direction from the axial direction passage and being eccentric from the center of the axial direction passage. It is also possible to have a circumferential passage that opens.

  In the fuel injection valve of the present invention, the axial passage may be closed at the end on the fuel chamber side.

  In the fuel injection valve of the present invention, a plurality of the circumferential passages may be provided.

  In the fuel injection valve of the present invention, the diameter of the circumferential passage may be equal to or smaller than the diameter of the fuel injection hole.

  In the fuel injection valve of the present invention, a plurality of the circumferential passages may be provided, and the sum of the cross-sectional areas of the circumferential passages may be greater than or equal to the sum of the cross-sectional areas of the fuel injection holes.

  In the fuel injection valve of the present invention, the number of the circumferential passages may be determined in consideration of the diameter and the sum of the cross-sectional areas.

  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 inlet part of the fuel injection valve concerning this Embodiment. It is a figure shown in order to demonstrate the swirl | flow flow formation part of an inlet connector. It is a figure shown in order to demonstrate the bottom face part of a fuel chamber. It is a figure which shows the flow of the fuel which flows in into a fuel chamber.

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. In the present embodiment, the injector housing 2 and the nozzle body 3 correspond to the “housing” of the present invention.

  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 control chamber 19 of the back pressure control portion 7.

  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.

  The valve body 6 is formed with a 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). Yes. The control chamber 19 communicates with an introduction-side orifice 20 formed in the valve body 6. The introduction-side orifice 20 is communicated with the second fuel passage 13 via a pressure introduction chamber 21 formed annularly between the valve body 6 and the injector housing 2 in the circumferential direction of the valve body 6. As a result, the introduction pressure from the common rail 12 is supplied to the control chamber 19.

  The control chamber 19 also communicates with an opening / closing orifice 23, and the opening / closing orifice 23 can be opened / closed by operating an electromagnetic valve 28 of a back pressure control unit 7 described later. The pressure receiving area of the top 5A of the valve piston 5 in the 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 solenoid valve 28, a holder 29, and a control chamber 19 as main elements. The electromagnetic 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 23. The pressure in the control chamber 19 can be released to the fuel return path 15. By operating the control valve body 24 in this way, the pressure of the control chamber 19 is controlled, and the back pressure of the valve needle 4 is controlled via the valve piston 5, so that the seat on the seat portion 17 of the valve needle 4 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 also acts on the top 5 </ b> A of the valve piston 5 in the control chamber 19 via the second fuel passage 13 and the pressure introduction chamber 21.
Therefore, in a state where the control chamber 19 is cut off from the fuel low pressure side by the control valve body 24, the valve needle 4 is driven by the back pressure of the control chamber 19 received through the valve piston 5 and the urging force of the nozzle spring 18. It is seated on the seat portion 17 of the body 3 and the fuel injection hole 16 is closed.

  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 23, the high pressure in the control chamber 19 causes the opening / closing orifice 23 to be opened. Through the fuel return path 15 to the fuel tank 51. Accordingly, the high pressure acting on the top 5A of the valve piston 5 in the control chamber 19 is released, and the valve needle 4 resists the urging 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 23 is closed by the control valve body 24 by demagnetizing the magnet 25, the valve needle 4 is moved to the seat position via the valve piston 5 by the pressure in the control chamber 19 and the biasing force of the nozzle spring 18. The fuel injection hole 16 is closed by being seated on the seat portion 17, and the fuel injection ends.

Next, the inlet portion 8 of the fuel injection valve 1 according to the present embodiment will be described in detail.
FIG. 2 shows an enlarged cross-sectional view of the inlet portion 8 of the fuel injection valve 1 shown in FIG.
The inlet portion 8 is configured by attaching an inlet connector 30 to an inlet opening 2 a formed in the injector housing 2. In the present embodiment, the inlet connector 30 is screwed into the inlet opening 2a in a liquid-tight manner.

  The inlet connector 30 includes a cylindrical connector body 31 having both ends opened in the axial direction, a flow path forming member 33 held in the connector body 31, and a swirl flow forming portion 35 fixed to the tip of the flow path forming member 33. And have. The outer periphery of the flow path forming member 33 is fixed in the connector body 31 in a liquid-tight manner by welding or welding. Further, the swirl flow forming portion 35 is fixed to the front end surface of the flow path forming member 33 by welding or the like.

  The flow path forming member 33 is formed with an axial passage 33a that opens to both ends in the axial direction and serves as an inflow passage for high-pressure fuel. The swirl flow forming portion 35 opens to one side in the axial direction, while an end portion on the fuel chamber 40 side described later is closed, and the opening communicates with the axial passage 33a of the flow path forming member 33. 35a and a circumferential passage 35b that is provided eccentrically from the center of the axial passage 35a and connects the axial passage 35a and the outer peripheral portion of the swirl flow forming portion 35 are formed.

  FIG. 3 shows an arrow view of the AA cross section of FIG. As shown in FIG. 3, the swirl flow forming portion 35 includes a plurality of circumferential passages 35 b provided extending in a tangential direction from the central axial passage 35 a. In the example shown in FIG. 3, eight circumferential passages 35b each extending in the tangential direction are formed at equal intervals.

  By mounting the inlet connector 30 thus configured in the inlet opening 2a, a fuel chamber is formed by the distal end portion (lower portion in FIG. 2) of the inlet connector 30 and the bottom surface portion 2aa of the inlet opening 2a. 40 is formed. In the present embodiment, a shim member 37 is sandwiched between the tip-side surface of the inlet connector 30 (the surface on the lower side in FIG. 2) and the bottom surface portion 2aa of the inlet opening 2a. The leakage of high-pressure fuel from the gap between the bottom surface 2aa of the inlet opening 2a is suppressed.

  In the bottom surface 2aa of the inlet opening 2a in the region of the fuel chamber 40, a first fuel passage 11a that communicates with the fuel reservoir chamber 14 of the nozzle body 3 and a second fuel passage that communicates with the control chamber 19 of the back pressure control unit 7 are provided. 13 is open.

  FIG. 4 shows an arrow view of the BB surface (the bottom surface portion 2aa of the inlet opening 2a) in FIG. As shown in FIG. 4, in the bottom surface portion 2aa of the inlet opening 2a in the region of the fuel chamber 40, the first fuel passage 11a opens to the outer peripheral portion of the bottom surface portion 2aa, and the second fuel passage 13 is the center of the bottom surface portion 2aa. Open to the part.

  The high-pressure fuel supplied from the common rail 12 and introduced into the inlet connector 30 flows through the axial passages 33a and 35a formed in the inlet connector 30, and then is introduced into the fuel chamber 40 through the circumferential passage 35b. . At this time, the circumferential passage 35b is provided eccentrically from the center of the axial passage 35a, and in particular, in the present embodiment, the circumferential passage 35b is provided in the tangential direction, so as shown in FIG. The fuel introduced into the fuel chamber 40 forms a swirling flow.

  Accordingly, the foreign matter mixed in the high-pressure fuel moves to the outer peripheral portion of the fuel chamber 40 by centrifugal force, so that it is difficult for the foreign matter to flow into the second fuel passage 13 leading to the control chamber 19 of the back pressure control unit 7. That is, the fuel injection valve 1 according to the present embodiment separates the first fuel by separating it into the outer peripheral portion of the fuel chamber 40 instead of collecting several μm of foreign matter in the fuel supplied from the common rail 12 to the inlet connector 30. The fuel is flowed to the passage 11a side, and fuel with relatively high cleanliness is flowed to the control chamber 19 side of the back pressure control unit 7. As a result, the erosion of the valve seat surface of the electromagnetic valve 28 of the back pressure control unit 7 is reduced by the foreign matter.

  Further, in the fuel injection valve 1 of the present embodiment, the diameter of the circumferential passage 35 b of the swirl flow forming portion 35 is designed to be equal to or smaller than the diameter of the fuel injection hole 16. For example, since the diameter of the fuel injection hole 16 is small and about 100 μm, the diameter of the circumferential passage 35b can be about 100 μm. Accordingly, a foreign substance having such a size as to clog the fuel injection hole 16 cannot pass through the circumferential passage 35b in advance, and the fuel injection hole 16 can be prevented from clogging.

  Furthermore, the fuel injection valve 1 of the present embodiment is designed such that the sum of the cross-sectional areas of the circumferential passages 35 b of the swirl flow forming portion 35 is equal to or greater than the sum of the cross-sectional areas of the fuel injection holes 16. Therefore, the pressure loss of the high-pressure fuel supplied from the common rail 12 to the fuel injection valve 1 is less likely to occur.

  That is, the diameter of the circumferential passage 35b is determined so as to be equal to or larger than the diameter of the fuel injection hole 16, and the total sectional area of the circumferential passage 35b is equal to or larger than the total sectional area of the fuel injection hole 16. The number of circumferential passages 35b is determined. By providing the circumferential passage 35b as described above, it is possible to prevent pressure loss of the high-pressure fuel and to prevent the fuel injection hole 16 from being clogged with foreign matter.

DESCRIPTION OF SYMBOLS 1: Fuel injection valve, 2: Injector housing, 2a: Inlet opening part, 2aa: Bottom part, 3: Nozzle body, 4: Valve needle, 5: Valve piston, 6: Valve body, 7: Back pressure control part, 8 : Inlet part, 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 , 18: Nozzle spring, 19: Control chamber, 20: Introduction side orifice, 21: Pressure introduction chamber, 22: Spring chamber, 23: Opening / closing orifice, 24: Valve ball, 25: Magnet, 26: Valve spring, 27 : Armature, 28: Solenoid valve, 29: Holder, 30: Inlet connector, 31: Connector body, 33: Flow path forming member, 33a: Axial direction Road, 35: swirling flow forming portion, 35a: axial passage, 35b: circumferential passage, 37: shim member, 40: fuel chamber, 51: fuel tank

Claims (7)

A housing having a first fuel passage communicating with the fuel injection hole and a second fuel passage communicating with the pressure control chamber, a valve needle provided so as to be movable back and forth in the housing, and adjusting a pressure in the pressure control chamber; A fuel injection valve comprising: a control valve that controls the opening and closing of the fuel injection hole by moving the valve needle forward and backward;
The housing includes an inlet opening, and an inlet connector having a high-pressure fuel introduction passage is attached to the inlet opening.
A fuel chamber is formed by an end surface portion of the inlet connector and a bottom surface portion of the inlet opening, and the first fuel passage is opened at an outer peripheral portion of the bottom surface portion of the region of the fuel chamber, and at the central portion, The second fuel passage opens,
A fuel injection valve characterized in that the high-pressure fuel introduced from the inlet connector into the fuel chamber can form a swirling flow.   The inlet connector includes an axial passage extending in the axial direction, and a circumferential passage extending in the circumferential direction from the axial passage and eccentric from the center of the axial passage and opening into the fuel chamber. The fuel injection valve according to claim 1.   The fuel injection valve according to claim 2, wherein an end of the axial passage on the fuel chamber side is closed.   The fuel injection valve according to claim 2, comprising a plurality of the circumferential passages.   The fuel injection valve according to any one of claims 2 to 4, wherein a diameter of the circumferential passage is equal to or smaller than a diameter of the fuel injection hole.   The fuel injection according to any one of claims 2 to 5, wherein a plurality of the circumferential passages are provided, and a sum of cross-sectional areas of the circumferential passages is equal to or greater than a sum of cross-sectional areas of the fuel injection holes. valve.   The fuel injection valve according to any one of claims 2 to 6, wherein the number of the circumferential passages is determined in consideration of a diameter thereof and a sum of the cross-sectional areas.

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