JP2010096100A - Fuel injection nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection nozzle 20 capable of stably injecting fuel, and preventing the nozzle body 23 from being deformed since it is cooled by cooling air and maintained at a predetermined position without being affected by an external force applied to the fuel injection nozzle 20. <P>SOLUTION: The fuel injection nozzle 20 is attached to a cylinder head 3. A cylindrical retaining nut 25 is fitted to a nozzle holder 21 and a nozzle body 23. The fuel injection nozzle is disposed in such a manner that the retaining nut 25 vertically extends through a cooling air passage 3c horizontally formed in the cylinder head 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection nozzle. Specifically, the present invention relates to a fuel injection nozzle positioning structure with respect to a cylinder head.

  In recent years, a direct injection type fuel system in which fuel is directly injected from a fuel injection nozzle into a combustion chamber in a cylinder has become the mainstream in diesel engines and the like. In this direct injection type engine, it is necessary to accurately determine the direction of spray injected from the fuel injection nozzle. Therefore, the fuel injection nozzle is firmly attached to the engine using a nozzle holding member, a nozzle holding bolt, or the like. .

  On the other hand, since an air-cooled diesel engine cools a fuel injection nozzle heated by combustion heat, it is necessary to blow cooling air around the fuel injection nozzle. Therefore, the cooling air is directly brought into contact with the fuel injection nozzle by disposing the fuel injection nozzle across the cooling air passage formed in the cylinder head. That is, the upper part of the nozzle holder of the fuel injection nozzle is supported by an attachment hole formed in the upper part of the cooling air passage, the nozzle body of the fuel injection nozzle is supported by the attachment hole formed in the lower part of the cooling air passage, and the other parts. Is configured to be cooled by cooling air. For example, it is as in known document 1.

However, since the mounting hole formed in the upper part of the cooling air passage needs to pass a retaining nut having a diameter larger than that of the nozzle holder, the mounting hole is formed between the nozzle holder and the mounting hole formed in the upper part of the cooling air passage. There is a gap. Moreover, the attachment hole formed in the lower part of the cooling air passage supports the nozzle body via a seal made of an elastic member in order to prevent leakage of combustion gas inside the combustion chamber. Therefore, when the fuel injection nozzle is fixed, if a bending moment occurs due to the uneven tightening force of the fixing bolt, the inclination of the fuel injection nozzle with respect to the combustion chamber varies, and the fuel spray position varies, or the nozzle body slides precisely. There has been a problem that the performance of the fuel injection nozzle is not stable due to the deformation of the hole and the movement of the needle valve being restricted.
JP 2003-49626 A

  The present invention has been made in view of the problems as described above, and is cooled by cooling air and maintains a predetermined position without being affected by external force applied to the fuel injection nozzle, thereby preventing deformation of the nozzle body. Thus, an object of the present invention is to provide a fuel injection nozzle that enables stable fuel injection.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in Claim 1, it is the structure which attaches a fuel-injection nozzle to a cylinder head, Comprising: A cylindrical retaining nut is externally fitted and connected with the nozzle holder and the nozzle body,
The retaining nut is disposed so as to vertically penetrate a cooling air passage formed in the cylinder head in the horizontal direction.

  The upper part formed in the upper part of the said cooling air path in Claim 2 in which the said retaining nut is inlay-fitted to the said nozzle holder and the said nozzle body. An inlay fitting is performed in the mounting hole, and an inlay fitting portion with the nozzle body is inlayed in a lower mounting hole formed in a lower portion of the cooling air passage.

  According to a third aspect of the present invention, the retaining nut is fitted in-slot with the lower mounting hole via a gasket.

  As effects of the present invention, the following effects can be obtained.

  Since the fuel injection nozzle is reinforced by the retaining nut and the retaining nut is supported by the upper and lower portions of the cooling air passage, the fuel injection nozzle is cooled by the cooling air. A predetermined position is maintained without being affected by an external force applied to the fuel injection nozzle, and deformation of the nozzle body is prevented. Thereby, the fuel injection nozzle can enable stable fuel injection.

  Since the fuel injection nozzle is supported by being fitted in the upper mounting hole and the lower mounting hole of the cooling air passage, the fuel injection nozzle is cooled by the cooling air and applied to the external force applied to the fuel injection nozzle. The predetermined position can be maintained without being affected and the deformation of the nozzle body can be prevented. Thereby, the fuel injection nozzle can enable stable fuel injection.

  According to the third aspect of the present invention, the sealing material at the tip of the nozzle body can be changed from an elastic member such as a fluororesin to a gasket such as copper having a low cost and high thermal conductivity. Thereby, the fuel injection nozzle can reduce the cost, increase the cooling efficiency of the nozzle body tip, and enable stable fuel injection.

  Next, a first embodiment of the fuel injection nozzle 20 which is an embodiment of the fuel injection nozzle according to the present invention will be described. In addition, the up-down direction is defined with the arrow U direction in FIG. 1 as the upward direction, and the left-right direction is defined with the arrow L direction as the left direction. Further, the front-rear direction is defined with the arrow F direction in FIG.

  First, an overall configuration of an air-cooled diesel engine 1 (hereinafter simply referred to as “engine 1”) having a fuel injection nozzle 20 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The fuel injection nozzle 20 according to the present invention is not limited to the engine 1 according to the present embodiment.

  As shown in FIG. 1, the engine 1 includes a cylinder block 2, a cylinder head 3, a crankshaft 4, a muffler 5, a fuel tank 6, and the like.

  The cylinder block 2 constitutes a main structure constituting the engine 1. The central portion of the cylinder block 2 includes one or a plurality of cylinders 2a in the vertical direction, and a piston 7 is provided in each cylinder 2a so as to be slidable back and forth. A crankcase 2b is formed in the lower part of the cylinder block 2, and the crankshaft 4 that is rotatably supported is supported in the front-rear direction. The piston 7 and the crankshaft 4 are connected by a connecting rod 8, and the reciprocating sliding motion of the piston 7 is transmitted to the crankshaft 4. On the right side of the crankcase 2b, a fuel injection pump 9, a cam shaft 10, a pump drive cam 11, a governor 12, and the like are disposed.

  The fuel injection pump 9 supplies a predetermined amount of fuel at a predetermined timing. The fuel injection pump 9 is driven by a pump drive cam 11 provided on a camshaft 10 that is linked and interlocked with the crankshaft 4. The fuel injection pump 9 sucks fuel from the fuel tank 6 and supplies the fuel to the combustion chamber 13 configured in the cylinder 2a.

  The governor 12 stabilizes the rotational speed of the engine 1. The governor 12 is connected to the camshaft 10 by a gear or the like (not shown), and controls the supply of fuel so as to suppress fluctuations in the rotational speed of the engine 1 due to load fluctuations.

  The cylinder head 3 is fixed to the upper part of the cylinder block 2, and the cylinder head 3, the cylinder 2a, and the piston 7 built in the cylinder 2a constitute a combustion chamber 13. As shown in FIG. 2, a valve arm chamber 16 including an air supply valve 14, an exhaust valve 15, a fuel injection nozzle 20, and the like is configured at the top of each cylinder 2 a. The cylinder head 3 is integrally formed with an air supply port 3a, an exhaust port 3b, and a cooling air passage 3c.

  The air supply valve 14 is opened and closed at a predetermined timing to supply outside air into the cylinder 2a. The supply valve 14 opens and closes to supply outside air from the supply port 3a into the cylinder 2a. A valve rod 14 a of the air supply valve 14 penetrates the cylinder block 2 upward and protrudes into the valve arm chamber 16, and a spring 17 is externally fitted in the valve arm chamber 16. The spring 17 biases upward so as to close the air supply valve 14.

  The exhaust valve 15 is opened and closed at a predetermined timing and discharges the exhaust gas after combustion in the cylinder 2a. The exhaust valve 15 opens and closes to discharge exhaust gas from the cylinder 2a to the exhaust port 3b. A valve rod 15 a of the exhaust valve 15 penetrates the cylinder block 2 upward and protrudes into the valve arm chamber 16, and a spring 17 is externally fitted in the valve arm chamber 16. The spring 17 biases upward so as to close the exhaust valve 15.

  As shown in FIG. 1, the fuel injection nozzle 20 injects fuel into the combustion chamber 13. The fuel injection nozzle 20 is connected to the fuel injection pump 9 and injects high-pressure fuel from the fuel injection pump 9 into the combustion chamber 13 at a predetermined timing. The fuel injection nozzle 20 includes a nozzle holder 21 (see FIG. 3) and a nozzle body 23 (see FIG. 3). The fuel injection nozzle 20 is disposed so that the tip of the nozzle body 23 protrudes from the valve arm chamber 16 through the cooling air passage 3c into the cylinder 2a.

  The muffler 5 reduces exhaust pressure and exhaust noise. The muffler 5 is connected to the exhaust port 3b and discharges exhaust gas into the atmosphere after reducing exhaust pressure and exhaust noise. The muffler 5 is disposed on the left side of the cylinder head 3.

  The fuel tank 6 stores fuel. The fuel tank 6 is connected to the fuel injection pump 9 through a hose, a filter, and the like, and the fuel in the fuel tank 6 is supplied to the fuel injection pump 9. The fuel tank 6 is disposed on the right side of the cylinder head 3.

  Next, the configuration of the fuel injection nozzle 20 will be described with reference to FIGS.

  As shown in FIG. 3, the fuel injection nozzle 20 includes a nozzle holder 21, a distance piece 22, a nozzle body 23, a needle valve 24, a retaining nut 25, and the like, and a fuel supply path 26 that supplies fuel. And a fuel discharge passage 27 for discharging excess fuel.

  The nozzle holder 21 constitutes a main structure constituting the fuel injection nozzle 20. A distance piece 22 and a nozzle body 23 are connected to the nozzle holder 21 by a retaining nut 25. The nozzle holder 21 includes therein a first fuel supply path 26 a that constitutes a part of the fuel supply path 26, a fuel discharge path 27, and a spring chamber 21 a, and includes a biasing spring 28. Further, the outer side surface of the nozzle holder 21 has an external thread portion 21b (see FIG. 4).

  The first fuel supply path 26 a supplies fuel from the fuel injection pump 9 to the nozzle body 23. The first fuel supply passage 26 a is formed from one end side (on the opposite nozzle body 23 side) of the nozzle holder 21 toward the other end side (nozzle body 23 side), and is connected to one end side of the nozzle holder 21. The fuel supply pipe 9a for supplying fuel from the nozzle 9 and the other end face of the nozzle holder 21 are communicated with each other.

  The fuel discharge path 27 discharges surplus fuel. The fuel discharge path 27 is formed from one end side to the other end side of the nozzle holder 21, and includes a discharge port formed on one end side of the nozzle holder 21 and a spring chamber 21 a formed on the other end side of the nozzle holder 21. Communicate.

  The spring chamber 21 a is provided with an urging spring 28. The spring chamber 21a is formed in a substantially cylindrical shape from the other end side end face of the nozzle holder 21 toward one end side. One end (on the side opposite to the nozzle body 23) of the spring chamber 21 a communicates with the fuel discharge path 27, and the other end (on the nozzle body 23 side) communicates with the other end side end face of the nozzle holder 21.

  The biasing spring 28 biases the needle valve 24. The biasing spring 28 is housed in the spring chamber 21a so as to be extendable and contractible.

  The distance piece 22 adjusts the position of the nozzle body 23. The distance piece 22 is formed in the same cross-sectional shape as the nozzle holder 21. The distance piece 22 has a first needle hole 24a at a position overlapping with the spring chamber 21a and a second fuel supply path 26b at a position overlapping with the first fuel supply path 26a. The end surface (on the side opposite to the nozzle body 23) and the other end surface (on the nozzle body 23 side) communicate with each other.

The nozzle body 23 forms the fuel injection port 23a. The nozzle body 23 has one end side (nozzle holder 21 side) formed in a substantially conical shape with the same cross-sectional shape as the distance piece 22, and has a fuel injection port 23a at the pointed end on the other end side (on the opposite nozzle holder 21 side). . The nozzle body 23 has a second needle hole 24b for inserting the needle valve 24 at a position overlapping with the first needle hole 24a. The nozzle body 23 has an end surface on one end side and a fuel injection port 23a on the other end side. Communicate.
The nozzle body 23 includes an oil pool portion 24c that stores fuel in the middle of the second needle hole 24b, and a third fuel supply passage 26c. The second fuel supply passage 26b and the oil pool portion 24c of the distance piece 22 Are communicated by the third fuel supply path 26c. The inner diameter of the second needle hole 24b is larger than the inner diameter (hereinafter simply referred to as “one side diameter”) from one end (nozzle holder 21 side) to the oil pool portion 24c, and the other end (anti-nozzle holder 21). The other end of the inner diameter of the second needle hole 24b is formed in a substantially conical shape.

  The needle valve 24 opens and closes the fuel injection port 23a. The needle valve 24 is formed slightly smaller than one side diameter of the second needle hole 24b, and is slidably mounted in the second needle hole 24b. One end (nozzle holder 21 side) of the needle valve 24 is formed with a protruding portion 24d and is inserted into the first needle hole 24a. A spring receiver 24e is fixed to the end of the projecting portion 24d, and a biasing spring 28 biases the needle valve 24 via the spring receiver 24e. The other end of the needle valve 24 (on the side opposite to the nozzle holder 21) is formed in the same conical shape as the other end of the second needle hole 24b, and the other end of the second needle hole 24b is urged by the urging force of the urging spring 28. The other end of the needle valve 24 is in close contact with the fuel injection port 23a.

The retaining nut 25 connects the nozzle holder 21, the distance piece 22, and the nozzle body 23. The retaining nut 25 is formed in a substantially cylindrical shape having an inner diameter that allows the nozzle holder 21, the distance piece 22, and the nozzle body 23 to be inserted without a gap, that is, an inner diameter that can be fitted with a slot. The retaining nut 25 has an inner thread portion 25a formed at an inner diameter portion at one end (on the opposite side of the nozzle body 23), and a step for locking the nozzle body 23 at the inner diameter portion at the other end (on the nozzle body 23 side). Attached portion 31c is formed. Furthermore, the retaining nut 25 is formed such that the outer diameter on one end side is larger than the outer diameter on the other end side and is larger than the outer diameter of the nozzle holder 21.
The retaining nut 25 has the nozzle body 23 and the distance piece 22 inserted therein, and the outer threaded portion 21b of the nozzle holder 21 and the inner threaded portion 25a of the retaining nut 25 are screwed together. At this time, the nozzle holder 21, the distance piece 22, and the nozzle body 23 are positioned by the positioning pins 29.

  With such a configuration, when the fuel injection nozzle 20 injects fuel, the fuel pressure-fed from the fuel injection pump 9 through the fuel supply pipe 9a is sent to the first fuel supply path 26a, the second fuel supply path 26b, and The oil accumulates in the oil pool portion 24c through the third fuel supply path 26c. When fuel accumulates in the oil reservoir 24c, the pressure in the oil reservoir 24c increases and pressure is applied to the needle valve 24 facing the oil reservoir 24c. When the force that the needle valve 24 receives from the oil reservoir 24c exceeds the biasing force that the needle valve 24 receives from the biasing spring 28, the needle valve 24 slides to one end side, and the other end of the second needle hole 24b and the needle The other end of the valve 24 is separated. As a result, the fuel injection port 23a is opened. The fuel that accumulates in the oil pool portion 24c is injected from the fuel injection port 23a through the gap between the needle valve 24 and the other diameter of the second needle hole 24b. At this time, a part of the fuel accumulated in the oil pool portion 24c reaches the spring chamber 21a of the nozzle holder 21 through a gap between the needle valve 24 and the one side diameter of the second needle hole 24b. The fuel that has reached the spring chamber 21 a is discharged from the fuel discharge path 27.

  Next, the mounting structure of the fuel injection nozzle 20 will be described with reference to FIG.

  The fuel injection nozzle 20 is inclined from the vertical into an upper mounting hole 30 formed in the upper portion of the cooling air passage 3c of the cylinder head 3 and a lower mounting hole 31 formed in the lower portion of the cooling air passage 3c, and the nozzle body Inserted into the combustion chamber 13 of each cylinder 2a with 23 facing downward. The inserted fuel injection nozzle 20 is fixed by the implantation bolt 32 and the nozzle holding plate 33 or the like.

  The upper mounting hole 30 is formed to have an inner diameter that allows the outer diameter of the other end of the retaining nut 25 to be inserted without a gap, that is, an inner diameter that allows a spigot fitting. The lower mounting hole 31 has an inner diameter that allows the outer diameter of one end of the retaining nut 25 to be inserted without a gap, that is, a large-diameter portion 31a formed to have an inner diameter that can be fitted with a spigot, and a tip portion of the nozzle body 23. A small-diameter portion 31b having an inner diameter slightly larger than the outer diameter. The large diameter part 31a is formed in the lower part of the cooling air passage 3c up to the middle part, and the small diameter part 31b is formed so as to communicate with the combustion chamber 13 at the center position of the large diameter part 31a. Therefore, the lower mounting hole 31 has a stepped portion 31c.

  The fuel injection nozzle 20 is inserted into the small-diameter portion 31b of the lower mounting hole 31 through a sealing material 34 having an end portion of the nozzle body 23 made of an elastic member such as a fluororesin, and one end portion of the retaining nut 25 Is inserted into the large-diameter portion 31 a of the lower mounting hole 31, and the other end of the retaining nut 25 is inserted into the upper mounting hole 30. At this time, the retaining nut 25 is formed so as to be inserted into both the upper mounting hole 31 and the lower mounting hole 31.

  The implantation bolt 32 and the nozzle pressing plate 33 are for fixing the fuel injection nozzle 20. The studs 32 are screwed into both sides of the upper mounting hole 30 in parallel with the fuel injection nozzle 20. The nozzle pressing plate 33 is disposed so as to straddle the upper portion of the nozzle body 23, and has a fixing hole 33 a at a position overlapping the implantation bolt 32. The nozzle pressing plate 33 fixes the fuel injection nozzle 20 by inserting the stud bolt 32 into the fixing hole 33a and tightening it downward with a nut 35 or the like.

  With such a configuration, the insertion depth of the fuel injection nozzle 20 is determined by the contact of the other end of the retaining nut 25 with the stepped portion 31 c of the lower mounting hole 31. The inclination of the fuel injection nozzle 20 is determined by fitting the retaining nut 25 into the upper mounting hole 30 and the lower mounting hole 31 in an inlay. As a result, the fuel injection nozzle 20 is cooled by the cooling air and supported by the upper mounting hole 30 and the lower mounting hole 31 without any gap.

As described above, the fuel injection nozzle 20 is attached to the cylinder head 3, and the cylindrical retaining nut 25 is externally fitted and connected to the nozzle holder 21 and the nozzle body 23. The cylinder head 3 is arranged so as to penetrate the cooling air passage 3c formed in the horizontal direction in the vertical direction.
With this configuration, the fuel injection nozzle 20 is reinforced by the retaining nut 25, and the retaining nut 25 is supported at the upper and lower portions of the cooling air passage 3c. The predetermined position is maintained without being affected by the external force applied to the fuel injection nozzle 20 while being cooled, and the deformation of the nozzle body 23 is prevented. Thereby, the fuel injection nozzle 20 can enable stable fuel injection.

The retaining nut 25 is fitted in the nozzle holder 21 and the nozzle body 23 with an inlay, and the inlay fitting portion with the nozzle holder 21 is inserted into an upper mounting hole 30 formed in the upper part of the cooling air passage 3c. Inlay fitting is performed, and the inlay fitting portion with the nozzle body 23 is inlay fitted into the lower mounting hole 31 formed in the lower portion of the cooling air passage 3c.
By configuring in this manner, the fuel injection nozzle 20 is supported by inlay fitting in the upper mounting hole 30 and the lower mounting hole 31 of the cooling air passage 3c, so that it is cooled by the cooling air and the fuel injection nozzle 20 The predetermined position can be maintained without being affected by the external force applied to the nozzle body 23 and deformation of the nozzle body 23 can be prevented. Thereby, the fuel injection nozzle 20 can enable stable fuel injection.

  Below, 2nd embodiment of the fuel injection nozzle 20 which is one Embodiment of the fuel injection nozzle 20 which concerns on this invention using FIG. 5 is described. Note that, in the following embodiments, the same points as those of the first embodiment described above are denoted by the same reference numerals, the detailed description thereof will be omitted, and differences will be mainly described.

  First, the mounting structure of the fuel injection nozzle 20 will be described.

  The fuel injection nozzle 20 is inclined from the vertical into an upper mounting hole 30 formed in the upper portion of the cooling air passage 3c of the cylinder head 3 and a lower mounting hole 31 formed in the lower portion of the cooling air passage 3c, and the nozzle body Inserted into the combustion chamber 13 of each cylinder 2a with 23 facing downward. The inserted fuel injection nozzle 20 is fixed by the implantation bolt 32 and the nozzle holding plate 33 or the like.

  The upper mounting hole 30 is formed to have an inner diameter that allows the outer diameter of the other end of the retaining nut 25 to be inserted without a gap, that is, an inner diameter that allows a spigot fitting. The lower mounting hole 31 has an inner diameter that allows the outer diameter of one end of the retaining nut 25 to be inserted without a gap, that is, a large-diameter portion 31a formed to have an inner diameter that can be fitted with a spigot, and a tip portion of the nozzle body 23. A small-diameter portion 31b having an inner diameter slightly larger than the outer diameter. The large diameter part 31a is formed in the lower part of the cooling air passage 3c up to the middle part, and the small diameter part 31b is formed so as to communicate with the combustion chamber 13 at the center position of the large diameter part 31a. Therefore, the lower mounting hole 31 has a stepped portion 31c.

  The fuel injection nozzle 20 has a front end portion of the nozzle body 23 inserted into the small diameter portion 31b of the lower mounting hole 31, and a side end portion of the retaining nut 25 with a gasket 44 made of copper or the like interposed therebetween. The other end of the retaining nut 25 is inserted into the upper mounting hole 30 and inserted into the large diameter portion 31 a of the mounting hole 31. At this time, the retaining nut 25 is formed so as to be inserted into both the upper mounting hole 30 and the lower mounting hole 31.

  With such a configuration, the insertion depth of the fuel injection nozzle 20 is determined by the other end portion of the retaining nut 25 and the stepped portion 31 c of the lower mounting hole 31 coming into contact with each other via the gasket 44. The inclination of the fuel injection nozzle 20 is determined by fitting the retaining nut 25 into the upper mounting hole 30 and the lower mounting hole 31 in-situ. As a result, the fuel injection nozzle 20 is cooled by the cooling air and supported by the upper mounting hole 30 and the lower mounting hole 31 without any gap.

As described above, the retaining nut 25 is characterized by being fitted into the lower mounting hole 31 through the gasket 44 with the gasket 44 interposed therebetween.
With this configuration, the sealing material 34 at the tip of the nozzle body 23 can be changed from an elastic member such as a fluororesin to a gasket 44 such as copper having a lower cost and higher thermal conductivity. Thereby, the fuel injection nozzle 20 can reduce the cost, increase the cooling efficiency of the tip of the nozzle body 23, and enable stable fuel injection.

1 is a front view showing an engine having a fuel injection nozzle according to the present invention. 1 is a side view showing an engine having a fuel injection nozzle according to the present invention. The block diagram which shows the structure of the fuel-injection nozzle which concerns on this invention. The block diagram which shows the attachment structure of the fuel-injection nozzle which concerns on 1st embodiment of this invention. The block diagram which shows the attachment structure of the fuel-injection nozzle which concerns on 2nd embodiment of this invention.

Explanation of symbols

1 Engine 3 Cylinder Head 3c Cooling Air Passage 20 Fuel Injection Nozzle 23 Nozzle Body 25 Retaining Nut

Claims (3)

A fuel injection nozzle is attached to the cylinder head,
A cylindrical retaining nut is externally fitted and connected to the nozzle holder and the nozzle body,
A fuel injection nozzle, wherein the retaining nut is disposed so as to vertically penetrate a cooling air passage formed in a cylinder head in a horizontal direction. The retaining nut is
Inlay fitting to the nozzle holder and the nozzle body,
A spigot fitting portion with the nozzle holder is fitted into a top mounting hole formed in an upper portion of the cooling air passage,
2. The fuel injection nozzle according to claim 1, wherein an inlay fitting portion with the nozzle body is inlay fitted into a lower mounting hole formed in a lower portion of the cooling air passage. The retaining nut is
The fuel injection nozzle according to claim 1 or 2, wherein a gasket is interposed to fit into the lower mounting hole in-slot.

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