JP2011112036A - Cooling structure of fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep fuel spray to a combustion chamber favorable, maintain engine performance and secure reliability by keeping low the temperature of the seat part of a nozzle tip body in a fuel injection valve to prevent deformation, wear or the like in a seat part. <P>SOLUTION: A structure includes a cooling passage 32 communicated to a passage 33 for receiving fuel from a fuel injection pump of a nozzle tip body 3 in a fuel injection nozzle 1 and performs cooling along an axial center of the nozzle tip body 3 by a fuel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cooling structure for a nozzle tip body of a fuel injection valve used in a direct injection diesel engine or the like.

Diesel engine combustion depends greatly on the state of fuel injection into the combustion chamber. The tip portion of the nozzle tip body of the fuel injection valve is exposed in the combustion chamber and is exposed to the combustion heat of the combustion chamber.
In addition, with the recent increase in output, the temperature in the combustion chamber during operation has increased. Of course, the temperature received by the tip of the nozzle tip body also increases.
Accordingly, the nozzle tip body seat portion of the fuel injection valve undergoes deformation or wear of the seat portion as the temperature rises. Deformation or wear of the seat part leads to poor sealing performance and poor fuel spraying to the combustion chamber, leading to deterioration of engine performance.

As a technique for solving this, a fuel injection valve heat insulation sleeve is interposed between the fuel injection valve insertion hole formed in the cylinder head and the fuel injection valve, and the fuel injection valve heat insulation sleeve is provided. There is known a structure in which a gasket portion extending outward in the radial direction of the fuel injection valve and a sleeve portion extending in the axial direction of the fuel injection valve are provided, and the sleeve portion is formed in a bellows shape.
This facilitates the assembly of the fuel injection valve to the cylinder head and increases the heat radiation from the fuel injection valve to the cylinder head, thereby ensuring the durability reliability of the fuel injection valve.

  As a prior art document, Japanese Patent Application Laid-Open No. 2007-107456 (Patent Document 1) has been proposed.

Japanese Unexamined Patent Publication No. 2007-107456

In Patent Document 1, the combustion heat received from the combustion chamber by the nozzle tip body of the fuel injection valve is brought into contact with the sleeve portion, the nozzle tip body, and the sleeve portion and the cylinder head, and the heat of the nozzle tip body is radiated to the cylinder head. I am letting.
However, as described above, higher output of the engine is required, the temperature of the combustion chamber when the engine is operating becomes high, and the conventional cooling method is insufficient.

The present invention was made to solve such problems, and by keeping the seat portion temperature of the nozzle tip body of the fuel injection valve low, deformation or wear of the seat portion is prevented,
The purpose is to maintain good fuel spray in the combustion chamber, maintain engine performance, and ensure reliability.

  The present invention achieves such an object. In a fuel injection valve cooling structure, the fuel injection passage communicates with a fuel reception passage from a fuel injection pump of a nozzle tip body constituting the fuel injection valve. Another cooling passage is provided along the axis of the nozzle tip body, and the nozzle tip body is cooled by fuel.

  With such a configuration, by providing a cooling passage for cooling with fuel in the nozzle tip body, it is possible to effectively suppress the temperature rise at the tip portion of the nozzle tip body, resulting in poor sealing performance of the needle valve seat portion of the nozzle tip body. And the deterioration of the performance of the internal combustion engine due to the poor fuel spray due to the poor sealability can be prevented.

  In the present invention, it is preferable that the cooling passage is disposed substantially opposite to the fuel receiving passage with respect to the axis of the fuel injection valve.

  With such a configuration, a cooling passage for cooling with fuel is provided on the substantially opposite side of the fuel receiving passage of the nozzle tip body, so the nozzle tip body can be cooled together with the fuel receiving passage side, so that the entire nozzle tip body is effective. Therefore, it is possible to prevent the deterioration of the performance of the internal combustion engine due to the poor sealability of the needle valve seat portion of the nozzle tip body and the poor fuel spray due to the poor sealability.

  In the present invention, it is preferable that the cooling passage is provided with an opening opening on the nozzle tip needle valve side in a front portion of the needle valve seat portion in the vicinity of the needle valve seat portion.

  With such a configuration, a cooling passage for cooling with fuel is provided on the substantially opposite side of the fuel receiving passage of the nozzle tip body, and an opening hole opened on the nozzle tip needle valve side is provided in the front portion of the needle valve seat portion. Since the fuel in the cooling passage substantially opposite to the fuel receiving passage is injected and replaced as the fuel of the internal combustion engine, the nozzle tip body can be cooled more effectively together with the fuel receiving passage side, so that the nozzle The entire tip body can be effectively cooled, and the deterioration of the performance of the internal combustion engine due to the poor sealability of the needle valve seat portion of the nozzle tip body and the poor fuel spray due to the poor sealability can be prevented.

  Preferably, in the present invention, in the cooling structure of the fuel injection valve, the nozzle continues along the axis of the nozzle tip body continuously to the fuel receiving passage from the fuel injection pump of the nozzle tip body constituting the fuel injection valve. A cooling passage that extends to the vicinity of the needle valve seat portion of the tip body and has an opening hole that opens to the nozzle tip needle valve side in a front portion of the needle valve seat portion, and cools the nozzle tip body with fuel. It is good to arrange.

  With such a structure, the cooling passage extends from the fuel receiving passage to the vicinity of the needle valve seat portion of the nozzle tip body, so the volume of the cooling passage for cooling the nozzle tip body by the fuel is reduced, so the fuel injection performance The reduction can be suppressed to the minimum, and the performance of the internal combustion engine can be maintained. Furthermore, since the fuel receiving part is simply moved to the nozzle side, the number of processing steps can be reduced.

  According to the present invention, the needle valve seat temperature of the nozzle tip body of the fuel injection valve is kept low, and the seat temperature of the nozzle tip body of the fuel injection valve is kept low, thereby preventing deformation or wear of the seat portion. Thus, the fuel spray to the combustion chamber can be kept good, and the maintenance and reliability of the engine performance can be ensured.

The schematic block diagram of the fuel injection valve which concerns on 1st Embodiment of this invention is shown. The schematic block diagram of the fuel injection valve which concerns on 2nd Embodiment of this invention is shown. The schematic block diagram of the fuel injection valve which concerns on 3rd Embodiment of this invention is shown. In the temperature comparison of the tip of the nozzle tip body, (A) is an enlarged view of the upper half of the central axis of the part (A) in FIG. 1 and shows the temperature measurement part, and (B) shows a temperature measurement value table.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

(First embodiment)
FIG. 1 shows a schematic configuration diagram of a fuel injection valve 1 in the first embodiment.
The fuel injection valve 1 includes the following components. The nozzle body 2 has a hollow cylindrical space portion, and a spring 23 that presses the nozzle tip needle valve 4 via the spring receiver 22 is accommodated in the space portion. Yes. A nozzle tip body 3 having a plurality of injection holes 35 facing the combustion chamber and spraying fuel into the combustion chamber and having a cylindrical space portion is fixed to the combustion chamber side of the engine of the nozzle body 2. A nozzle tip needle valve 4 is fitted in the space of the nozzle tip 3 so as to be slidable in the axial direction of the nozzle tip body 3.
The nozzle tip needle valve 4 is formed in the nozzle tip body 3 so as to be continuous with the first body portion 43 having a thick nozzle body 2 side, the second body portion 44 thinner than the first body portion 43, and the second body portion 44. The needle valve seat portion 36 is pressed by a spring 23 and includes a conical portion 45 that seals fuel into the fuel injection valve 1. Further, the first shoulder portion 41 that is a step portion between the first body portion 43 and the second body portion 44 and the second shoulder portion 42 that is a step portion between the second body portion 44 and the conical portion 45 are provided. .
The second shoulder portion 42 is located at a front portion of the needle valve seat portion 36.
A gap is formed between the second body 44 and the nozzle tip body 3 through which fuel sprayed into the combustion chamber can pass.

In addition, fuel is pumped to the nozzle body 2 from a fuel injection device (not shown) through a fuel pipe 22 into a fuel passage 21 disposed in the nozzle body 2.
The nozzle tip body 3 is connected to the fuel passage 21 and passes through a fuel receiving passage 33 that is a tubular fuel receiving passage disposed along the axis of the nozzle tip body 3. The fuel accumulates in the fuel reservoir 31 surrounded by the one shoulder 41 and the recess 37 formed in the nozzle tip body 3.
The concave portion 37 has a semicircular cross section on the inner peripheral surface of the nozzle tip body 3 and is formed in an annular shape.

  Further, a cooling passage 32 is formed in the nozzle tip body 3 at a position opposite to the fuel receiving passage 33 with respect to the axis of the nozzle tip body 3 and extending substantially to the vicinity of the second shoulder 42 in parallel with the axis. . The cooling passage 32 is connected to the concave portion 37 at an intermediate portion of the nozzle tip body 3 in the axial direction, and is filled with fuel from the fuel injection device.

  The operation of the fuel injection valve 1 is as follows. The pressure of the fuel pumped from the fuel injection device acts on the first shoulder 41, and the nozzle tip needle valve 4 moves to the left side in FIG. To do. When the nozzle tip needle valve 4 moves to the left side, a gap is formed between the needle valve seat portion 36 and the conical portion 45, and the pressure of the fuel pumped from the fuel injection device acts on the conical portion 45, and the nozzle tip needle valve 4 As the fuel further moves to the left side, fuel is sprayed from the nozzle 35 to the combustion chamber via the sac volume 34. When there is no fuel pumping from the fuel injection device, the pressing force of the spring 23 overcomes the fuel pressure, the gap between the needle valve seat portion 36 and the conical portion 45 is closed, and fuel injection is stopped.

  The fuel pressure-fed from the fuel injection device reaches the cooling passage 32 through an annular recess 37 formed on the inner peripheral surface of the nozzle tip body 3, and the nozzle tip body 3 is connected to the cooling passage 32 and the fuel receiving passage 33 side. In addition, since the entire nozzle tip body 3 can be effectively cooled by the fuel, the performance of the engine due to poor sealing performance of the needle valve seat portion 36 of the nozzle tip body 3 and poor fuel spraying due to poor sealing performance. Deterioration can be prevented.

(Second Embodiment)
Since the basic structure is the same as that of the first embodiment, the parts different from the first embodiment will be described. The same parts are denoted by the same reference numerals, and description thereof is omitted.
FIG. 2 is a schematic configuration diagram of the fuel injection valve 5 in the second embodiment.
A nozzle tip body 6 having a plurality of injection holes 65 facing the combustion chamber and spraying fuel into the combustion chamber and having a cylindrical space portion is fixed to the combustion chamber side of the nozzle body 2 of the engine. A nozzle tip needle valve 4 is fitted in the nozzle tip body 6 so as to be slidable in the axial direction of the nozzle tip body 6.
The nozzle tip body 6 is connected to the fuel passage 21 and passes through a fuel receiving passage 64 that is a tubular fuel receiving passage disposed along the axis of the nozzle tip body 3. The fuel accumulates in the fuel reservoir 61 surrounded by the shoulder 41 and the recess 65 formed in the nozzle tip body 3.
The recess 65 has a semicircular cross section on the inner peripheral surface of the nozzle tip body 3 and is formed in an annular shape.

Further, a cooling passage 62 is formed in the nozzle tip body 6 at a position opposite to the fuel receiving passage 64 with respect to the axis of the nozzle tip body 6 and extending substantially parallel to the axis to the vicinity of the second shoulder 42. . The cooling passage 62 is connected to the recess 65 at an intermediate portion, and is filled with fuel.
The second shoulder portion 42 is located at the front portion of the needle valve seat portion 66.
Further, an opening 63 opened to the nozzle tip needle valve 4 side is disposed near the second shoulder 42 of the nozzle tip needle valve 4 at the end of the cooling passage 62.

  The fuel pumped from the fuel injection device reaches the cooling passage 62 via an annular recess 65 formed on the inner peripheral surface of the nozzle tip body 6, and the fuel that has filled the cooling passage 62 is also injected during fuel injection. Therefore, the fuel in the cooling passage 62 is always replaced, and the nozzle tip body 3 is directly cooled by the fuel at the cooling passage 32 and the fuel receiving passage 33 side, so that the entire nozzle tip body 6 can be effectively cooled. Further, it is possible to prevent deterioration in engine performance due to poor sealing performance of the needle valve seat portion 66 of the nozzle tip body 6 and poor fuel spraying due to poor sealing performance.

(Third embodiment)
Since the basic structure is the same as that of the first embodiment, the parts different from the first embodiment will be described. The same parts are denoted by the same reference numerals, and description thereof is omitted.
FIG. 3 shows a schematic configuration diagram of the fuel injection valve 7 in the third embodiment.
In the nozzle tip body 8, a cooling passage 81 that also serves as a fuel receiving passage communicating with the fuel passage 21 is opened near the second shoulder 42 of the nozzle tip needle valve 8 toward the nozzle tip needle valve 4.
The second shoulder portion 42 is located at the front portion of the needle valve seat portion 82.
The fuel pressure-fed from the fuel injection device flows into the cooling passage 81 opened to the nozzle tip needle valve 4 in the vicinity of the second shoulder portion 42 of the nozzle tip needle valve 4 and is injected from the nozzle 83 into the combustion chamber.
Therefore, since the portion where the fuel passes through the nozzle tip body 8 is long, the cooling of the nozzle tip body 8 by the fuel increases by the length. Since the nozzle tip body 8 is directly cooled by the fuel in the cooling passage 81 that always replaces, the entire nozzle tip body 8 can be effectively cooled, and the sealing performance and the sealing performance of the needle valve seat portion 82 of the nozzle tip body 8 are poor. It is possible to prevent deterioration in engine performance due to poor fuel spray.

FIG. 4 shows the temperature measurement result during engine operation according to the present embodiment. FIG. 4A is an enlarged view of the upper half of the central axis of FIG. Shows the measured temperature values in the table.
In this experiment, the fuel temperature was about 80 ° C. Since it varies depending on engine specifications and load conditions, it is a value implemented as a certain experimental condition.
The measurement result is compared with the first embodiment of the present application compared to the conventional fuel injection valve.
It can be seen that the temperature of the needle valve seat portion 36 of the nozzle tip body 3 that is most desired to lower the temperature in the present application has a temperature reduction effect of 50 ° C. compared to the conventional one.

  To suppress the temperature rise near the nozzle of the fuel injection valve of the engine, to prevent deformation or wear of the seat part, to keep the fuel spray to the combustion chamber well, and to maintain the engine performance and reliability. Target fuel injection valve

1, 5, 7, 9 Fuel injection valve 2 Nozzle body 3, 6, 8, 10 Nozzle tip body 4 Nozzle tip needle valve 6 Control device 9 Injection pipe 12 Load sensor 21 Fuel passage 32, 62, 81 Cooling passage 33, 64 , 81 Fuel receiving passage 35, 65, 83 Injection hole 36, 66, 82, 106 Needle valve seat portion 41 First shoulder portion 42 Second shoulder portion 45 Conical portion 101 Ceramic

Claims (4)

  In the fuel injection valve cooling structure, the nozzle tip body constituting the fuel injection valve communicates with the fuel receiving passage from the fuel injection pump of the nozzle tip body, and a cooling passage different from the fuel receiving passage is connected to the axis of the nozzle tip body. A cooling structure for a fuel injection valve, wherein the nozzle tip body is cooled by fuel.   2. The cooling structure for a fuel injection valve according to claim 1, wherein the cooling passage is disposed on a substantially opposite side of the fuel receiving passage with respect to an axis of the fuel injection valve.   3. The fuel injection valve according to claim 1, wherein the cooling passage is provided with an opening opening on the nozzle tip needle valve side in a front portion of the needle valve seat near the needle valve seat. Cooling structure.   In the cooling structure of the fuel injection valve, in the vicinity of the needle valve seat portion of the nozzle tip body along the axis of the nozzle tip body continuously to the fuel receiving passage from the fuel injection pump of the nozzle tip body constituting the fuel injection valve And a cooling passage for cooling the nozzle tip body with fuel is provided in the front portion of the needle valve seat portion, the opening portion opening toward the nozzle tip needle valve side. Cooling structure of the injection valve.

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