JP2006233821A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve for solving a problem of micro-leakage without largely changing the conventional fuel injection valve. <P>SOLUTION: In the fuel injection valve 1, a nozzle body 3 having a second fuel passage 14 is fixed to a tip part of an injector housing 2 having a first fuel passage 13, by threadably attaching a nozzle nut 9. A high pressure seal part 26 is formed to a connection part of the first and second fuel passages 13, 14, and the high pressure fuel supplied from the outside is fed to a fuel reservoir chamber 15 in the nozzle body 3 through the first and second fuel passages 13, 14. The injector housing 2, the nozzle body 3, and the nozzle nut 9 form an annular space 27 for temporarily collecting the fuel that has leaked out of the high pressure seal part 26. A communication passage 28 makes the annular space 27 communicate with a fuel low pressure part in the injector housing 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve for injecting and supplying fuel into a cylinder of an internal combustion engine.

  For example, in the case of a common rail fuel injection system, high pressure fuel supplied from a common rail is sent to a fuel injection valve fixed to a cylinder of the internal combustion engine, and high pressure fuel is injected into the cylinder from the fuel injection valve. ing. By the way, this type of fuel injection valve is formed by attaching a nozzle body to the tip of an injector housing with a nozzle nut, and high-pressure fuel from the common rail passes through a fuel passage formed between the injector housing and the nozzle body and enters the nozzle body. It is configured to be sent to the fuel reservoir chamber formed in the above.

  For this reason, there is a possibility that so-called micro-leakage in which the high-pressure fuel in the fuel passage leaks from the seal surface between the injector housing and the nozzle body that becomes the connection point of the fuel passage may occur. If such a fuel leak occurs, there is a possibility that a problem arises in that the fuel is mixed into the engine oil and its lubricity is lowered.

Therefore, as seen in Patent Documents 1 and 2, measures are taken such as making the seal surface into a concave shape, or forming a groove on the seal surface for returning high pressure fuel leaking from the seal surface to the fuel low pressure side. ing.
JP 2003-139014 A JP 2003-139015 A

  However, even with the proposed prior art, it is difficult to prevent fuel leakage from the seal surface formed between the injector housing and the nozzle body to such an extent that the above-mentioned problem does not occur. There has been a demand for significant changes that lead to an increase in cost, such as further improving the performance or providing a special seal member.

  It is an object of the present invention to provide a fuel injection valve that can improve the problem of microleakage without significant changes over conventional products.

  In order to solve the above problems, according to the present invention, a nozzle body in which a second fuel passage is formed at a tip end portion of an injector housing in which a first fuel passage is formed is screwed into a nozzle nut in the injector housing. And the high pressure fuel is supplied from the outside through the first and second fuel passages to form the nozzle body. In a fuel injection valve configured to be sent to a fuel reservoir chamber, an annular shape is formed to collect fuel leaked from the high pressure seal portion, which is formed including the injector housing, the nozzle body, and the nozzle nut. A fuel comprising: a space; and a communication passage for communicating the annular space with a fuel low pressure portion in the injector housing. Event is proposed.

  According to the present invention, even a conventional product can solve the problem of microleakage without requiring a significant change.

  Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the drawings.

  A fuel injection valve 1 according to the present invention includes an injector housing 2, a nozzle body 3, a nozzle needle 4, and a back pressure control unit 5. Positioning in which two or more first positioning holes 6 are formed in the injector housing 2 and the same number of second positioning holes 7 are formed in the nozzle body 3 and are inserted into the first positioning hole 6 and the second positioning hole 7, respectively. The positions of the pins 8 are aligned with each other, and the nozzle body 3 is attached to the tip of the injector housing 2 by a nozzle nut 9 as described later, and the back pressure control unit 5 is provided above the nozzle body 3.

  The fuel from the fuel tank 10 is pressurized by the fuel pump 11 and stored as high pressure fuel in the common rail 12, and this high pressure fuel is supplied to the fuel injection valve 1. A first fuel passage 13 is formed in the injector housing 2, a second fuel passage 14 is formed in the nozzle body 3, and a fuel reservoir chamber 15 is formed facing the pressure receiving portion 4 </ b> A of the nozzle needle 4. Has been.

  The high-pressure fuel from the common rail 12 can always be supplied to the fuel reservoir chamber 15 through the first fuel passage 13 and the second fuel passage 14. A part of the first fuel passage 13 extends upward in the drawing, forms a fuel return passage 16 from the back pressure control portion 5 portion, and allows fuel to return to the fuel tank 10. The fuel recirculation path 16 forms a fuel leak path together with a spring chamber 19 and the like which will be described later.

  The nozzle body 3 is formed with an arbitrary number of fuel injection holes 17 at the front end thereof, and the front end of the nozzle needle 4 seats on the sheet portion 18 connected to the injection hole 17 to close the injection hole 17. When the nozzle needle 4 is lifted from the seat portion 18, the nozzle hole 17 is released and fuel can be injected.

  A spring chamber 19 formed at the center of the injector housing 2 above the nozzle needle 4 has a spring seat 20, a nozzle spring 21 that biases the nozzle needle 4 in the seat direction of the seat portion 18, and a spring seat 20. And a valve piston 22 that abuts from above. The back pressure control unit 5 controls the valve piston 22, that is, the back pressure of the nozzle needle 4 is controlled, thereby controlling the seat and lift of the nozzle needle 4 via the spring seat 20. The upper part of the nozzle needle 4 can slide in the clearance seal hole 23 of the nozzle body 3. The spring chamber 19 communicates with the fuel return passage 16 on the low pressure side, and the nozzle body 3 separates the high pressure side (fuel reservoir chamber 15) and the low pressure side (spring chamber 19) at the clearance seal hole 23. Yes.

  The injector housing 2 has a first seal surface 24 orthogonal to the length direction on the bottom surface, and the nozzle body 3 has a second seal surface 25 orthogonal to the length direction on the top surface. Yes.

  A thread groove 91A is formed on the inner peripheral surface near the rear end opening 91 of the nozzle nut 9, and a thread groove 2A corresponding to the thread groove 91A is formed on the outer peripheral surface of the injector housing 2. Therefore, the first seal surface 24 and the second seal surface 25 ensure a predetermined surface pressure by screwing the screw groove portion 91A and the screw groove portion 2A and tightening the nozzle nut 9 with a predetermined seat tightening force. A high-pressure seal portion 26 is formed between the first fuel passage 13 and the second fuel passage 14 through which the high-pressure fuel passes so that fuel does not leak out of the fuel injection valve 1.

  An annular groove 92 is formed inside the nozzle nut 9 and opposed to the high-pressure seal portion 26, so that the injector housing 2, the nozzle body 3, and the nozzle nut 9 are assembled as shown in FIG. In this case, an annular space 27 for once collecting high-pressure fuel leaked from the high-pressure seal portion 26 is formed including the injector housing 2, the nozzle body 3, and the nozzle nut 9. A communication passage 28 is provided for allowing the high-pressure fuel once collected in the annular space 27 to escape to the fuel low-pressure side.

  FIG. 2 shows a bottom view of the injector housing 2. A first seal surface 24 is formed along the periphery of the bottom surface 2 </ b> B of the injector housing 2, and a bottom-side opening end 13 </ b> A of the first fuel passage 13 is surrounded by the first seal surface 24. . A central portion of the bottom surface 2B surrounded by the first seal surface 24 is a recess 2C, and an opening 2D provided in the recess 2C communicates with the spring chamber 19.

  In order to allow the high-pressure fuel collected in the annular space 27 to escape from the opening 2 </ b> D to the low-pressure side of the fuel via the spring chamber 19, a groove 29 constituting the communication path 28 is formed in the first seal surface 24. The groove 29 has one end connected to the annular space 27 and the other end connected to the recess 2C. Accordingly, the high-pressure fuel leaking from the high-pressure seal portion 26 once enters the annular space 27 and escapes from the annular space 27 through the communication path 28 to the fuel low-pressure side. As a result, it is possible to reliably prevent the microleakage from the high-pressure seal portion 26 from leaking through the threaded portion between the injector housing 2 and the nozzle nut 9.

  Since the fuel injection valve 1 is configured as described above, the problem of micro-leakage can be solved without requiring additional parts at a low cost that requires only a slight machining of the injector housing 2 and the nozzle nut 9. be able to. Therefore, there is no change in the assembly of the product compared to the conventional one, and no change is made outside the product, so there is no interference with the cylinder head of the internal combustion engine, so that it is of the conventional specification It will not cause any trouble to exchange with. In addition, it does not affect the disassembly or recycling of the product.

  In the embodiment shown in FIGS. 1 and 2, the annular space 27 for once collecting the fuel leaked from the high pressure seal portion 26 is secured by forming an annular groove 92 inside the nozzle nut 9. . However, the annular space 27 can also be secured by processing the injector housing 2 or the nozzle body 3.

  FIG. 3 shows the injector housing 2 in which an annular space 27A for collecting fuel leaked from the high-pressure seal portion 26 is secured by chamfering a part near the high-pressure seal portion 26 into a tapered portion 2T. This is an example. In this case, instead of forming the tapered portion 2T, or in addition to this, a chamfering process similar to the above may be performed on the nozzle body 3 side to secure the annular space 27A.

  FIG. 4 shows an example in which the annular space 27A is secured by forming the notch 2S in the injector housing 2 instead of the taper 2T. Also in this case, instead of or in addition to the cutout portion 2S, a configuration in which the annular space 27A is secured by forming a cutout portion having the same purpose on the nozzle body 3 side may be employed. Furthermore, you may use a notch part and a taper part together.

  FIG. 5 shows an example in which the outer diameter of the injector housing 2 is made larger than the outer diameter of the nozzle body 3, thereby forming a stepped portion X near the high-pressure seal portion 26, thereby securing the annular space 27A. is there.

  In each of the embodiments described above, the example in which the first seal surface 24 and the second seal surface 25 are in direct pressure contact to form the high-pressure seal portion 26 has been described. It is not limited to.

  In FIG. 6, a plate member 100 is disposed between the injector housing 2 and the nozzle body 3 for the purpose of improving the degree of freedom of the oil feed hole processing and imparting the guide function of the nozzle spring to constitute the high pressure seal portion 26A. The other embodiment is the same as the structure shown in FIG. Therefore, the same reference numerals are given to the portions corresponding to the respective portions in FIG. 1 among the respective portions in FIG. 6, and the description thereof is omitted.

The principal part sectional view showing an example of an embodiment of the invention. The enlarged view of the bottom face of the injector housing of FIG. The figure which shows the principal part of the modification of embodiment of this invention shown in FIG. The figure which shows the principal part of the other modification of Embodiment of this invention shown in FIG. The figure which shows the principal part of another modification of embodiment of this invention shown in FIG. The figure which shows the principal part of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Injector housing 2B Bottom face 2C Recessed part 2D Opening 2T Taper part 2S Notch part 3 Nozzle body 4 Nozzle needle 9 Nozzle nut 13 First fuel passage 13A Bottom side opening end 14 Second fuel passage 15 Fuel reservoir chamber
17 injection hole 24 first seal surface 25 second seal surface 26, 26A high pressure seal portion 27, 27A annular space 28 communication passage 29 groove 91A screw groove portion 92 annular groove 100 plate member X step portion

Claims (1)

A nozzle body in which a second fuel passage is formed at the tip of the injector housing in which the first fuel passage is formed is fixed by screwing a nozzle nut onto the injector housing, and the first and second A high pressure seal portion is formed at a connection portion of the fuel passage so that high pressure fuel supplied from the outside is sent to the fuel reservoir chamber in the nozzle body through the first and second fuel passages. In the fuel injection valve
An annular space formed to include the injector housing, the nozzle body, and the nozzle nut for temporarily collecting fuel leaked from the high pressure seal portion;
A fuel injection valve comprising: a communication passage for communicating the annular space with a fuel low pressure portion in the injector housing.

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