JP2018040314A - Fuel injection nozzle - Google Patents

Abstract

Dispersion of time until fuel injected from a plurality of radially provided nozzle holes reaches a peripheral wall surface of a combustion chamber is suppressed, and combustion is made uniform.
A fuel is supplied to the inside, and a plurality of injection holes for injecting the fuel to the outside are provided radially, and the distance from at least one injection hole to the peripheral wall surface of the combustion chamber is different from the other injection holes. A fuel injection nozzle arranged in a state different from a distance from a hole to the peripheral wall surface, so that the time until the fuel injected from the plurality of injection holes reaches the peripheral wall surface is the same The at least one nozzle hole has a shape different from that of the other nozzle holes.
[Selection] Figure 3

Description

  The present invention relates to a fuel injection nozzle.

  2. Description of the Related Art Conventionally, an injector that injects fuel into a combustion chamber of a diesel engine has a fuel injection nozzle having a plurality of radial injection holes. According to this injector, since the fuel is injected radially from the plurality of nozzle holes, the fuel can be efficiently burned in the combustion chamber.

  By the way, the injector may be arranged in an eccentric or inclined state from the axial center of the combustion chamber due to the arrangement layout of the supply / exhaust valves. In such a case, in the above-described fuel injection nozzle, the fuel injection characteristics from the plurality of radially provided nozzle holes are all the same, so the combustion efficiency may deteriorate.

  In Patent Document 1, by increasing the diameter of at least one of the plurality of radially provided nozzle holes, the fuel injection characteristics are different from those of the other nozzle holes, thereby achieving uniform combustion. Are disclosed.

Japanese Patent Application Laid-Open No. 08-028455

  In the technique described in the cited document 1, the hole diameter of the nozzle hole is changed to make the fuel injection amount from each nozzle hole uniform, thereby achieving uniform combustion. However, the cited document 1 does not consider the variation in time until the combustion chamber reaches the peripheral wall surface, and it cannot be said that uniform combustion is sufficiently achieved.

  An object of the present invention is to make combustion uniform by suppressing variations in time until fuel injected from a plurality of radially provided nozzle holes reaches the peripheral wall surface of a combustion chamber.

  In the fuel injection nozzle according to the present invention, fuel is supplied to the inside, and a plurality of injection holes for injecting the fuel to the outside are provided radially, and from at least one injection hole to the peripheral wall surface of the combustion chamber A fuel injection nozzle arranged at a distance different from the distance from another nozzle hole to the peripheral wall surface, and a time until the fuel injected from the plurality of nozzle holes reaches the peripheral wall surface The at least one nozzle hole has a different shape from the other nozzle holes so as to be the same.

  ADVANTAGE OF THE INVENTION According to this invention, the dispersion | variation in time until the fuel injected from the several nozzle hole provided radially reaches the surrounding wall surface of a combustion chamber can be suppressed, and combustion can be made uniform.

Diesel engine longitudinal section The principal part longitudinal cross-sectional view of the fuel-injection nozzle which concerns on 1st Embodiment AA sectional view of FIG. Diagram showing the relationship between the length of the small-diameter hole and the fuel speed The principal part longitudinal cross-sectional view of the fuel-injection nozzle which concerns on 2nd Embodiment BB sectional view of FIG. Diagram showing the relationship between the length of the straight hole and the fuel speed The principal part longitudinal cross-sectional view of the fuel-injection nozzle which concerns on 3rd Embodiment CC sectional view of FIG. Diagram showing the relationship between nozzle hole taper angle and fuel velocity

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described below is an example, and the present invention is not limited to this embodiment.

(First embodiment)
First, with reference to FIG. 1, the structure of the diesel engine which concerns on 1st Embodiment is demonstrated. As shown in FIG. 1, the engine 1 includes a cylinder 2, a cylinder head 3, a piston 4, an intake port 5, an exhaust port 6, an intake valve 7, an exhaust valve 8, a fuel injection nozzle 100, and the like.

  A combustion chamber 9 is formed in the space between the cylinder 2 and the cylinder head 3, and fuel is directly injected into the combustion chamber 9 from the fuel injection nozzle 100. The piston 4 reciprocates along the inner wall 2 a of the cylinder 2. A recess 10 is formed at the top of the piston 4. The recess 10 has a raised center at the bottom, and the recess 10 forms a part of the combustion chamber 9.

  The tip of the fuel injection nozzle 100 is exposed in the cylinder 2, and fuel is injected radially from a plurality of radially formed injection holes (details will be described later). The fuel injection nozzle 100 is connected to a common rail (not shown), and high-pressure fuel stored in the common rail is constantly supplied to the fuel injection nozzle 100.

The fuel injection nozzle 100 is inclined with respect to the central axis O ₁ of the cylinder 2 at a position eccentric from the central axis O ₁ of the cylinder 2 as shown in FIG. 1 due to the layout of the intake valves 7 and the exhaust valves 8. It is arranged in the state.

  Next, the fuel injection nozzle 100 according to the first embodiment will be described with reference to FIGS. As shown in FIG. 2, the fuel injection nozzle 100 includes an injector-type fuel injection device, and includes a nozzle body 101 and a needle 102 that is slidably provided in the nozzle body 101.

  The nozzle body 101 includes a cylindrical portion 103 and a hemispherical portion 104 provided on the distal end side of the cylindrical portion 103. In the space between the inner peripheral surface 103a of the cylindrical portion 103 and the outer peripheral surface 102a of the needle 102, a fuel passage 105 through which high-pressure fuel supplied from the common rail flows is formed. Further, the hemispherical portion 104 is provided with a fuel reservoir 106.

  A seal portion 103 b is provided on the distal end side of the cylindrical portion 103, and the fuel injection nozzle 100 is opened when the taper portion 102 b of the needle 102 is separated from the seal portion 103 b, and a fuel pool 106 is formed from the fuel passage 105. Is supplied with high pressure fuel. Further, the fuel injection nozzle 100 is closed by the taper portion 102b coming into contact with the seal portion 103b, and the fuel supply is stopped.

The thickness of the hemispherical portion 104 is uniform, and a plurality of injection holes for injecting fuel from the fuel reservoir 106 into the combustion chamber 9 are formed in the hemispherical portion 104. The plurality of nozzle holes are arranged at four locations so as to extend radially at equal intervals around the fuel reservoir 106. That is, each nozzle hole is arranged around the central axis O ₂ of the fuel injection nozzle 100 so that adjacent ones are shifted by 90 °.

  In the following description, of the four nozzle holes, the one facing the exhaust valve 8 is defined as the first nozzle hole 108, and the second nozzle is rotated clockwise from the first nozzle hole 108 when the fuel injection nozzle 100 is viewed from the tip side. A hole 109, a third nozzle hole 110, and a fourth nozzle hole 111 are used.

  The first to fourth nozzle hole inlets 108a to 111a, which are openings on the fuel reservoir 106 side of the first to fourth nozzle holes 108 to 111, are circular, and the diameters of the nozzle hole inlets 108a to 111a are all the same.

  The first injection hole 108 facing the exhaust valve 8 is connected to the first injection hole 108a on the fuel reservoir 106 side from the first injection hole 108a and the first large diameter hole part 108c having a diameter larger than that of the first small diameter hole part 108b. Is provided. The diameter of the first small diameter hole portion 108b and the diameter of the first large diameter hole portion 108c are constant.

  The second injection hole 109 adjacent to the first injection hole 108 has a second large diameter larger than the second small diameter hole part 109b and the second small diameter hole part 109b from the second injection hole inlet 109a on the fuel reservoir 106 side. A hole 109c is provided. The diameter of the second small diameter hole portion 109b and the diameter of the second large diameter hole portion 109c are constant. Further, the length of the second small diameter hole 109b is longer than the length of the first small diameter hole 108b.

  The third nozzle hole 110 facing the first nozzle hole 108 across the central axis of the fuel injection nozzle 100 has a third small diameter hole portion 110b and a third small diameter hole from the third nozzle hole inlet 110a on the fuel reservoir 106 side. A third large-diameter hole portion 110c having a larger diameter than the portion 110b is provided. The diameter of the third small diameter hole portion 110b and the diameter of the third large diameter hole portion 110c are constant. The length of the third small diameter hole portion 110b is longer than the length of the second small diameter hole portion 109b.

  The fourth injection hole 111 adjacent to the first injection hole 108 and the third injection hole 110 is larger than the fourth small diameter hole part 111b and the fourth small diameter hole part 111b from the fourth injection hole inlet 111a on the fuel reservoir 106 side. A fourth large-diameter hole 111c having a diameter is provided. The diameter of the fourth small diameter hole portion 111b and the diameter of the fourth large diameter hole portion 111c are constant. The length of the fourth small diameter hole 111b is equal to the length of the second small diameter hole 109b.

  The first to fourth small diameter holes 108b to 111b correspond to the first part of the present invention. The first to fourth large-diameter holes 108c to 111c correspond to the second part of the present invention.

  The first to fourth nozzle holes 108 to 111 are formed as follows. That is, in the first step, the first to fourth small diameter holes 108b to 111b are formed from the outer surface side (combustion chamber 9 side) using a small diameter drill. In the subsequent second step, first to fourth large-diameter holes 108c to 111c are formed from the outer surface side (combustion chamber 9 side) using a large-diameter end mill.

  In the second step, it is possible to adjust the length of the first to fourth small diameter holes 108b to 111b by adjusting the processing depth of the end mill. The first to fourth nozzle holes 108 to 111 may be formed with a small diameter hole portion and a large diameter hole portion in one step using a counterbore drill (step drill).

  Next, the operation of the first embodiment will be described. When the needle 102 of the fuel injection nozzle 100 is driven to open the fuel injection nozzle 100, fuel is supplied from the fuel passage 105 to the fuel reservoir 106, and the fuel is supplied from the first to fourth injection hole inlets 108a to 111a. It flows into the first to fourth injection holes 108 to 111 and is injected into the combustion chamber 9.

  Here, when the shape of the nozzle hole is a stepped shape in which the fuel reservoir 106 side (inlet side) has a small diameter and the combustion chamber 9 side (outlet side) has a large diameter as in this embodiment, the small diameter hole A relationship as shown in FIG. 4 exists between the length of the portion and the speed of the fuel injected from the injection hole.

Therefore, the speed _{V 108} of the fuel injected from the first injection holes 108 is smaller than the speed _{V 109} and _{V 111} of the fuel injected from the second injection holes 109 and the fourth nozzle hole 111. Further, the velocity V ₁₁₀ of the fuel injected from the third injection hole 110 is larger than V ₁₀₉ and V ₁₁₁ .

As described above, the fuel injection nozzle 100 is disposed at a position that is eccentric from the central axis O ₁ of the cylinder 2 and is inclined with respect to the central axis O ₁ of the cylinder 2. Therefore, the distance from the second injection hole 109 and the fourth injection hole 111 to the inner wall 2a of the cylinder 2 is longer than the distance from the first injection hole 108 to the inner wall 2a, and the distance from the third injection hole 110 to the inner wall 2a. Shorter than.

  In the present embodiment, the lengths of the small diameter holes 108b to 111b are set so that the time taken for the fuel injected from the nozzles 108 to 111 to reach the inner wall 2a is the same. Therefore, the combustion state in the cylinder 2 can be made uniform and combustion failure can be suppressed.

  Moreover, in this Embodiment, the length of each small diameter hole part 108b-111b is set so that a fuel may be ignited at the timing when the fuel injected from each injection hole 108-111 arrives at the inner wall 2a. Therefore, it is possible to reduce the cooling loss caused by the fuel reaching the inner wall 2a before the ignition and cooling the inner wall 2a.

  As described above, according to the first embodiment, a plurality of nozzle holes arranged in a radial manner are formed into stepped nozzle holes including a small diameter hole part and a large diameter hole part. It becomes possible to adjust the speed of the fuel injected from the nozzle hole.

  Therefore, each nozzle hole 108 is adjusted by adjusting the processing depth of each large-diameter hole part 108c-111c in each nozzle hole 108-111 according to the distance from each nozzle hole 108-111 to the inner wall 2a of the cylinder 2. The time until the fuel injected from ˜111 reaches the inner wall 2a can be made the same. Thereby, the combustion state in the cylinder 2 can be made uniform, and combustion failure can be suppressed.

  If the time from fuel injection to ignition is known, the processing depth of each of the large-diameter holes 108c to 111c is adjusted, and the timing at which the fuel injected from the nozzle holes reaches the inner wall 2a of the cylinder 2; It is possible to match the timing of ignition. Thereby, the cooling loss by the fuel reaching the inner wall 2a of the cylinder 2 and cooling the inner wall 2a can be reduced.

  Furthermore, the flow of fuel injected from the nozzle holes 108 to 111 can be optimized by adjusting the processing depth of the large diameter holes 108c to 111c in consideration of the air flow in the cylinder 2. it can.

(Second Embodiment)
The fuel injection nozzle 200 according to the second embodiment will be described with reference to FIGS. Since the basic structure is the same as that of the first embodiment, redundant description is omitted.

  In 1st Embodiment, the length of the small diameter hole part was adjusted by making a nozzle hole into a small diameter hole part and a large diameter hole part. On the other hand, in the second embodiment, the diameter of the nozzle hole is increased in a tapered shape from the middle.

  As shown in FIGS. 5 and 6, in the fuel injection nozzle 200, the first to fourth injection hole inlets 208 a to 211 a that are openings on the fuel reservoir 206 side of the first to fourth injection holes 208 to 211 are circular, The diameters of the injection hole inlets 208a to 211a are all the same. Moreover, the diameter of each nozzle hole 208-211 is constant to the middle. Each of the nozzle holes 208 to 211 is tapered from the combustion chamber 9 side.

  The first injection hole 208 facing the exhaust valve 8 is provided with a first straight hole 208b and a first tapered hole 208c that gradually increases in diameter from the first injection hole inlet 208a on the fuel reservoir 206 side. The taper angle in the first tapered hole 208c is, for example, 45 °.

  The second injection hole 209 adjacent to the first injection hole 208 has a second straight hole 209b longer than the first straight hole 208b and a diameter that gradually increases from the second injection hole inlet 209a on the fuel reservoir 206 side. Two tapered holes 209c are provided. The taper angle of the second tapered hole portion 209c is equal to the taper angle of the first tapered hole portion 208c.

  A third nozzle hole 210 facing the first nozzle hole 208 across the central axis of the fuel injection nozzle 200 has a third length longer than the second straight hole 209b from the third nozzle hole inlet 210a on the fuel reservoir 206 side. A straight hole 210b and a third tapered hole 210c that gradually increases in diameter are provided. The taper angle in the third tapered hole portion 210c is equal to the taper angle of the first tapered hole portion 208c.

  The 4th nozzle hole 211 adjacent to the 1st nozzle hole 208 and the 3rd nozzle hole 210 is the same shape as the 2nd nozzle hole 209, the 4th nozzle hole inlet 211a, the 4th straight hole part 211b, and the 4th taper shape. It has a hole 211c.

  The first to fourth straight holes 208b to 211b correspond to the first part of the present invention. The first to fourth tapered holes 208c to 211c correspond to the second part of the present invention.

  Next, the operation of the second embodiment will be described. When the needle 202 of the fuel injection nozzle 200 is driven to open the fuel injection nozzle 200, fuel is supplied from the fuel passage 205 to the fuel reservoir 206, and fuel is injected from the injection holes 208 to 211.

  As in the present embodiment, when each of the injection holes 208 to 211 is composed of straight holes 208 b to 211 b having the same diameter and tapered holes 208 c to 211 c having the same taper angle, the straight holes 208 b to 211 b A relationship as shown in FIG. 7 exists between the length and the speed of the fuel injected from each of the nozzle holes 208 to 211.

Therefore, the speed V ₂₀₈ of the fuel injected from the first injection hole 208 is lower than the speeds V ₂₀₉ and V _{211 of the} fuel injected from the second injection hole 209 and the fourth injection hole 211. Further, the velocity V ₂₁₀ of the fuel injected from the third injection hole 210 is larger than V ₂₀₉ and V ₂₁₁ .

  In the present embodiment, the first to fourth tapered hole portions 208c to 211c are provided so that the time taken for the fuel injected from the injection holes 208 to 211 to reach the inner wall 2a is the same. . Therefore, the combustion state in the cylinder 2 can be made uniform and combustion failure can be suppressed.

  Also in the present embodiment, as in the first embodiment, the lengths of the straight hole portions 208b to 211b of the respective injection holes 208 to 211 are such that the fuel injected from the respective injection holes 208 to 211 is the inner wall. The fuel is set to ignite at the timing of reaching 2a.

  Therefore, the timing at which the fuel injected from the injection holes 208 to 211 reaches the inner wall 2a is the same as the timing at which the fuel is ignited. Thereby, the cooling loss by the fuel reaching the inner wall 2a of the cylinder 2 and cooling the inner wall 2a can be reduced.

  Furthermore, in this Embodiment, since each injection hole 208-211 was comprised from the straight hole part 208b-211b and the taper-shaped hole part 208c-211c, there exists an effect shown below.

  The fuel that has passed through the straight hole portion spreads by its own pressure in the tapered hole portion, becomes an air-fuel mixture, and tends to advance along the hole wall portion. The air-fuel mixture that has advanced along the hole wall portion of the tapered hole portion is peeled off from the hole wall portion in the middle of the taper hole portion.

  At this time, the flow of the air-fuel mixture peeled off from the hole wall is disturbed and mixed with more air, so that the combustion state in the cylinder 2 is improved and combustion failure can be further suppressed.

(Third embodiment)
With reference to FIGS. 8-10, the fuel-injection nozzle 300 which concerns on 3rd Embodiment is demonstrated. Since the basic structure is the same as that of the first embodiment, redundant description is omitted.

  In the fuel injection nozzle 300 shown in FIGS. 8 and 9, the first to fourth injection hole inlets 308 a to 311 a that are openings on the fuel reservoir 106 side of the first to fourth injection holes 308 to 311 are circular, and each injection hole The diameters of the inlets 308a to 311a are all the same.

  On the other hand, the first to fourth nozzle hole outlets 308b to 311b that are openings on the combustion chamber 9 side of the nozzle holes 308 to 311 are circular, and at least one nozzle hole outlet among the nozzle hole outlets 308b to 311b. The diameter of is different from the diameter of other nozzle hole outlets.

  That is, the opening areas of the first to fourth nozzle hole inlets 308a to 311a are equal, and the opening area of at least one of the first to fourth nozzle hole outlets 308b to 311b is the same as that of the other nozzle hole outlets. It is different from the opening area.

  As shown in FIG. 8, the first nozzle hole 308 has a diameter that increases in a taper shape from the first nozzle hole inlet 308a toward the first nozzle hole outlet 308b. The taper angle in the first nozzle hole 308 is, for example, 90 °.

  The second nozzle hole 309 adjacent to the first nozzle hole 308 is expanded in a taper shape with a taper angle of 45 ° from the second nozzle hole inlet 309a toward the second nozzle hole outlet 309b.

  The third nozzle hole 310 facing the first nozzle hole 308 across the central axis of the fuel injection nozzle 300 expands in a tapered shape with a taper angle of 15 ° from the third nozzle hole inlet 310a toward the third nozzle hole outlet 310b. It has a diameter.

  The fourth nozzle hole 311 adjacent to the first nozzle hole 308 and the third nozzle hole 310 has the same shape as the second nozzle hole 309, and has a taper angle from the fourth nozzle hole inlet 311a toward the fourth nozzle hole outlet 311b. The diameter is increased in a tapered shape at 45 °.

  Next, the operation of the third embodiment will be described. When the needle 302 of the fuel injection nozzle 300 is driven to open the fuel injection nozzle 300, fuel is supplied from the fuel passage 305 to the fuel reservoir 306, and fuel is injected from the injection holes 308 to 311.

  When each of the nozzle holes 308 to 311 has a tapered shape that expands from the nozzle hole inlet toward the nozzle hole outlet as in the present embodiment, fuel injection is injected from each nozzle hole 308 to 311 according to the taper angle. The state changes. In particular, the relationship shown in FIG. 9 exists between the taper angle and the fuel speed.

Therefore, the speed V ₃₀₈ of the fuel injected from the first injection hole 308 is smaller than the speeds V ₃₀₉ and V _{311 of the} fuel injected from the second injection hole 309 and the fourth injection hole 311. Further, the velocity V ₃₁₀ of the fuel injected from the third injection hole 310 is larger than V ₃₀₉ and V ₃₁₁ .

  In the present embodiment, the taper angles in the first to fourth injection holes 308 to 311 are set so that the time taken for the fuel injected from the injection holes 308 to 311 to reach the inner wall 2a is the same. Yes. Therefore, the combustion state in the cylinder 2 can be made uniform and combustion failure can be suppressed.

  Also in the present embodiment, the taper angles in the first to fourth injection holes 308 to 311 are set so that the fuel is ignited at the timing when the fuel injected from the injection holes 308 to 311 reaches the inner wall 2a. Has been.

  Therefore, the timing at which the fuel injected from each of the nozzle holes 308 to 311 reaches the inner wall 2a is the same as the timing at which the fuel is ignited. Thereby, the cooling loss by the fuel reaching the inner wall 2a of the cylinder 2 and cooling the inner wall 2a can be reduced.

  Furthermore, in this Embodiment, since each nozzle hole 308-311 was made into the taper shape, there exists the effect shown below.

  The fuel that has flowed into the tapered nozzle hole from the nozzle hole inlet spreads by its own pressure to become an air-fuel mixture, and tries to advance along the tapered hole wall. The air-fuel mixture that has traveled along the hole wall part peels off from the hole wall partway.

  At this time, the flow of the air-fuel mixture peeled off from the hole wall is disturbed and mixed with more air, so that the combustion state in the cylinder 2 is improved and combustion failure can be further suppressed.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and may be appropriately combined or modified without departing from the spirit of the present invention. Is possible.

  The present invention is suitably used for a fuel injection nozzle for a diesel engine.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 2a Inner wall 3 Cylinder head 4 Piston 5 Intake port 6 Exhaust port 7 Intake valve 8 Exhaust valve 9 Combustion chamber 10 Recess 100, 200, 300 Fuel injection nozzle 101 Nozzle body 102, 202, 302 Needle 102a Outer surface 102b Taper Part 103 Cylindrical part 103a Inner peripheral surface 103b Seal part 104 Hemisphere part 105, 205, 305 Fuel passage 106, 206, 306 Fuel reservoir 108, 208, 308 First injection hole 108a, 208a, 308a First injection hole inlet 108b First 1 small diameter hole portion 108c first large diameter hole portion 109, 209, 309 second injection hole 109a, 209a, 309a second injection hole inlet 109b second small diameter hole portion 109c second large diameter hole portion 110, 210, 310 third Injection hole 110a, 210a, 310a 3 injection hole inlet 110b 3rd small diameter hole part 110c 3rd large diameter hole part 111, 211, 311 4th injection hole 111a, 211a, 311a 4th injection hole inlet 111b 4th small diameter hole part 111c 4th large diameter hole part 208b First straight hole portion 208c First tapered hole portion 209b Second straight hole portion 209c Second tapered hole portion 210b Third straight hole portion 210c Third tapered hole portion 211b Fourth straight hole portion 211c Fourth tapered hole Portion 308b First nozzle hole outlet 309b Second nozzle hole outlet 310b Third nozzle hole outlet 311b Fourth nozzle hole outlet

Claims (7)

A plurality of injection holes for supplying fuel to the inside and injecting the fuel to the outside are provided radially, and the distance from at least one injection hole to the peripheral wall surface of the combustion chamber is from the other injection holes to the circumference. A fuel injection nozzle arranged in a state different from the distance to the wall surface,
The at least one injection hole has a shape different from that of the other injection holes so that the time until the fuel injected from the plurality of injection holes reaches the peripheral wall surface is the same.
Fuel injection nozzle. Each of the plurality of nozzle holes includes a first portion having the same diameter.
The length of the first portion in the at least one nozzle hole is different from the length of the first portion in the other nozzle hole.
The fuel injection nozzle according to claim 1. The inner side opening areas of the plurality of nozzle holes are equal,
The outside opening area of the at least one nozzle hole is different from the outside opening area of the other nozzle hole,
The fuel injection nozzle according to claim 1. The at least one nozzle hole is provided on the outer side of the first portion, and includes a second portion having a larger diameter than the first portion.
The fuel injection nozzle according to claim 2. The diameter of the second portion is constant;
The fuel injection nozzle according to claim 4. The diameter of the second portion is widened toward the outside side,
The fuel injection nozzle according to claim 4. The diameter of the at least one nozzle hole increases toward the outside,
The fuel injection device according to claim 3.

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