JP7159142B2 - Fluid flow pipe - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to fluid flow conduits, for example fluid flow conduits for supplying fluids, such as fuel-containing gases for automobiles, to an engine.

2. Description of the Related Art Conventionally, an intake device having an intake passage connected to an internal combustion engine has been proposed (see, for example, Patent Document 1). This intake device has an upstream curved portion curved on the upstream side of the intake passage and a downstream curved portion curved on the downstream side. In this intake device, in a cross section perpendicular to the extending direction of the intake passage in the curved downstream portion, the downstream portion first gap between the inner surface of the intake passage on the outer side of the curve and the inner surface of the intake passage on the inner side of the curve in the downstream curved portion. Gradually decrease along the inspiratory flow direction. Further, in this intake device, the downstream second interval between the intake passage inner surfaces facing each other perpendicularly to the opposing intake passage inner surfaces having the downstream first interval is gradually increased along the intake air flow direction. As a result, according to the intake device disclosed in Patent Document 1, it is possible to suppress the separation of the intake air flow and reduce the pressure loss in the curved portion of the intake passage.

Japanese Patent No. 6394154

By the way, in the conventional gas circulation tube, the resistance of the fluid may increase when flowing through the curved portion of the gas circulation tube.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluid flow pipe capable of reducing an increase in resistance due to a curved portion of a fluid passing through the pipe.

A fluid circulation tube according to an aspect of the present invention is a fluid circulation tube having a space through which a fluid flows, and is characterized by having a curved portion that curves along a transition curve whose curvature continuously changes.

According to this aspect, in the fluid flow tube, the curvature of the curved portion through which the fluid flows continuously changes according to the relaxation curve, and the path of the fluid, such as gas, passing through the inside of the tube changes rapidly when the fluid passes through the curved portion. Therefore, it is possible to reduce the resistance increase due to the curved portion of the fluid passing through the interior.

In the fluid circulation pipe according to the aspect of the present invention, the curved portion may have a curvature of the transition curve that decreases continuously along the direction of circulation of the fluid. Thereby, the fluid circulation tube can further prevent an increase in the resistance of the fluid passing through the inside of the curved portion. For example, when the fluid is gas, it is also possible to prevent the rebounding of the fluid due to the curved portion in the fluid flow pipe and to prevent adverse effects on the acoustic effect due to the rebound of the fluid flowing through the fluid flow pipe. becomes.

In the fluid circulation pipe according to the aspect of the present invention, the curved portion may have a curvature of the transition curve that increases continuously along the direction of circulation of the fluid. Thereby, the fluid circulation tube can further prevent an increase in the resistance of the fluid passing through the inside of the curved portion. For example, when the fluid is gas or the like, the fluid flow pipe prevents the fluid from rebounding due to the curved portion in the fluid flow pipe and adversely affects the acoustic effect due to the rebound of the fluid flowing through the fluid flow pipe. can also be prevented.

In the fluid flow pipe according to an aspect of the present invention, the curved portion includes a first curved portion that curves along a relaxation curve whose curvature continuously decreases in the direction of flow of the fluid up to a predetermined location; and a second curved portion that curves along a transition curve whose curvature continuously increases in the direction of flow of the fluid. Thereby, the fluid circulation tube can further prevent an increase in the resistance of the fluid passing through the inside of the curved portion. For example, when the fluid is gas or the like, the fluid flow pipe prevents the fluid from rebounding due to the curved portion in the fluid flow pipe and adversely affects the acoustic effect due to the rebound of the fluid flowing through the fluid flow pipe. can also be prevented.

In the fluid flow tube according to one aspect of the present invention, the transition curve may be a clothoid curve. Thereby, the fluid circulation tube can further prevent an increase in the resistance of the fluid passing through the inside of the curved portion. For example, when the fluid is gas or the like, the fluid flow pipe prevents the fluid from rebounding due to the curved portion in the fluid flow pipe and adversely affects the acoustic effect due to the rebound of the fluid flowing through the fluid flow pipe. can also be prevented.

In the fluid flow tube according to one aspect of the present invention, the fluid may be gas. The fluid flow tube can further prevent an increase in resistance of the fluid passing through the curved portion. For example, when the fluid is gas or the like, the fluid flow pipe prevents the fluid from rebounding due to the curved portion in the fluid flow pipe and adversely affects the acoustic effect due to the rebound of the fluid flowing through the fluid flow pipe. can also be prevented.

The fluid flow pipe according to one aspect of the present invention may be an intake pipe. Thereby, the fluid circulation tube can further prevent an increase in the resistance of the fluid passing through the inside of the curved portion. For example, when the fluid is gas or the like, the fluid flow pipe prevents the fluid from rebounding due to the curved portion in the fluid flow pipe and adversely affects the acoustic effect due to the rebound of the fluid flowing through the fluid flow pipe. can also be prevented.

The fluid circulation pipe according to one aspect of the present invention may be for automobiles. As a result, the fluid circulation pipe can effectively prevent an increase in the resistance of the fluid passing through the curved portion in various fluid circulation pipes such as an intake manifold and an exhaust manifold in the fluid circulation pipe for automobiles.

The fluid flow pipe according to one aspect of the present invention may be an intake manifold. As a result, the fluid circulation pipe can effectively prevent an increase in the resistance of the fluid passing through the curved portion of the intake manifold inside the fluid circulation pipe for automobiles.

ADVANTAGE OF THE INVENTION According to this invention, the fluid circulation pipe which can reduce the resistance increase based on the curved part of the fluid which passes through an inside is realizable.

FIG. 1A is an explanatory diagram of the concept of a curved portion using transition curves. FIG. 1B is an explanatory diagram of the concept of a curved portion using transition curves. FIG. 2 is a diagram showing an example of a fluid circulation pipe according to an embodiment of the invention. FIG. 3 is a schematic diagram showing an example of a common fluid circulation pipe. FIG. 4 is a schematic diagram of a gas flow tube according to an embodiment of the present invention; FIG. 5 is a schematic diagram of a gas flow pipe according to a comparative example of the present invention. FIG. 6 shows a case where the first curved portion and the second curved portion are clothoid curves in FIG. 2 and air is introduced into the gas flow pipe at a flow rate of 2.5 m ³ /min. 2 is a diagram showing analysis results of the relationship between the bending diameter of the tube and the pressure loss when air is introduced into the gas flow tube 2 at a flow rate of 2.5 m ³ /min with two curved portions formed into circular arcs, respectively. FIG. . FIG. ⁷ shows the flow velocity at each position when the first curved portion and the second curved portion in FIG. is a diagram showing the analysis results of , in terms of color densities. FIG. 8 shows the flow velocity at ^each position when the first curved portion and the second curved portion in FIG. is a diagram showing the analysis results of , in terms of color densities. FIG. ⁹ shows the flow velocity at each position when the first curved portion and the second curved portion in FIG. is a diagram showing the analysis results of , in terms of color densities. FIG. 10 is an analysis of the flow velocity at ^each position when the first curved portion and the second curved portion are formed into circular arcs with a diameter of 30 mm in FIG. It is a figure which represented the result by the light and shade of a color. FIG. 11 is an analysis of the flow velocity at ^each position when the first curved portion and the second curved portion are formed into circular arcs with a diameter of 45 mm in FIG. It is a figure which represented the result by the light and shade of a color. FIG. 12 is an analysis of the flow velocity at ^each position when the first curved portion and the second curved portion are formed into circular arcs with a diameter of 65 mm in FIG. It is a figure which represented the result by the light and shade of a color. FIG. 13 shows a case where the first curved portion and the second curved portion are clothoid curves in FIG. 2 and air is introduced into the gas flow tube at a flow rate of 4.0 m ³ /min. 2 is a diagram showing analysis results of the relationship between the bending diameter of the tube and the pressure loss when air is introduced into the gas flow tube 2 at a flow rate of 4.0 m ³ /min with two curved portions formed into circular arcs, respectively. FIG. . FIG. 14 shows the flow velocity at ^each position when the first curved portion and the second curved portion in FIG. is a diagram showing the analysis results of , in terms of color densities. FIG. 15 shows the flow velocity at ^each position when the first curved portion and the second curved portion in FIG. is a diagram showing the analysis results of , in terms of color densities. FIG. 16 shows the flow velocity at ^each position when the first curved portion and the second curved portion in FIG. is a diagram showing the analysis results of , in terms of color densities. FIG. 17 is an analysis of the flow velocity at ^each position when the first curved portion and the second curved portion are formed into circular arcs with a diameter of 30 mm in FIG. It is a figure which represented the result by the light and shade of a color. FIG. 18 is an analysis of the flow velocity at ^each position when the first curved portion and the second curved portion in FIG. It is a figure which represented the result by the light and shade of a color. FIG. 19 is an analysis of the flow velocity at ^each position when the first curved portion and the second curved portion are formed into circular arcs with a diameter of 65 mm in FIG. It is a figure which represented the result by the light and shade of a color.

First, with reference to FIGS. 1A and 1B, the concept of a curved portion using transition curves will be described. FIG. 1A and FIG. 1B are explanatory diagrams of the concept of a curved portion using relaxation curves. 1A and 1B show an example in which a vehicle 102 traveling on a straight portion 101A of an automobile road 101 passes through curved portions 101B and 101C as curved portions. Further, FIG. 1A shows a case where the curved portion 101B of the motorway 101 is provided with a constant curvature R, and FIG. It shows an example provided as a curve along.

As shown in FIG. 1A, when the curvature R of the curved portion 101B of the motorway 101 is set to be constant, when the vehicle 102 enters the curved portion 101B from the straight portion 101A, there is a It is necessary to rotate the handle 103 in one direction at once (see arrow A1 in FIG. 1A). In the curved portion 101B, the vehicle 102 stops the operation of the steering wheel 103, holds the rotation angle of the steering wheel 103 constant, and then returns the steering wheel 103 at once at the end of the curved portion 101B. (see arrow A2 in FIG. 1A). Thus, when the curvature R of the curved portion 101B is set constant, the vehicle 102 needs to perform abrupt steering operations near the entrance and exit of the curved portion 101B. If such a sudden steering operation is performed, the change in acceleration in the width direction of the automobile 102 becomes large, and the ride comfort may deteriorate.

On the other hand, as shown in FIG. 1B, when the curved portion 101C of the motorway 101 has a curvature RA following a transition curve such as a clothoid curve, the curved portion 101C of the motorway 101 is Curvature RA continuously changes from one end side to the other end side. Therefore, when the automobile 102 goes straight, the steering wheel 103 is gradually turned toward the maximum curvature RA portion 101D of the curved portion 101C, and the steering wheel 103 is gradually returned from the maximum curvature portion 101D toward the straight portion 101A. (see arrows A3 and A4 in FIG. 1B). As a result, the automobile 102 can continuously change the operation of the steering wheel 103 from the entrance to the exit of the curved portion 101C, and can pass through the curved portion 101C without having to operate the steering wheel 103 abruptly.

Thus, when the curved portion 101C along the curvature RA utilizing the transition curve is provided, the change in movement of the substance moving along the transition curve is compared with the case where the curvature R of the curved portion 101B is constant. can be made different. The inventor of the present invention focused on the above phenomenon, and made the curved portion of the fluid flow pipe through which the fluid flowed have a shape along such a relaxation curve, so that the fluid passing through the fluid flow pipe Based on the idea that the increase in resistance can be reduced, the present invention was completed.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications. In addition, the following embodiments can be implemented in combination as appropriate.

FIG. 2 is a schematic diagram showing an example of a fluid circulation tube according to an embodiment of the present invention, and FIG. 3 is a schematic diagram showing an example of a general fluid circulation tube. In addition, in the following embodiments, a gas flow pipe through which the gas A flows will be described as an example of the fluid flow pipe.

As shown in FIG. 2, the gas flow pipe 1 according to the present embodiment is used, for example, as an intake manifold for automobiles. The gas circulation pipe 1 is connected to a gas introduction part 10 that introduces an external gas A into the gas circulation pipe 1 . Gas A includes air and fuel-containing gas. The gas flow pipe 1 includes a first straight portion 11A connected to the gas introducing portion 10, a first curved portion 11B extending from the first straight portion 11A, a second straight portion 11C extending from the first curved portion 11B, and a second straight portion 11C extending from the first curved portion 11B. It has a second curved portion 11D extending from the second straight portion 11C and a third straight portion 11E extending from the second curved portion 11D.

The gas introduction part 10 has a function of filtering dust in the atmosphere, such as an air cleaner. The structure of the gas introduction part 10 can be changed as appropriate as long as it can introduce the gas A into the gas flow pipe 1. For example, the gas introduction part 10 does not necessarily have a function of filtering dust.

The gas flow pipe 1 passes the gas A introduced from the gas introduction portion 10 through a first straight portion 11A, a first curved portion 11B, a second straight portion 11C, and a second curved portion, which are upstream in the direction of flow of the gas A. 11D and the third straight portion 11E in order to supply an engine or the like provided at a later stage. The first straight portion 11A, the first curved portion 11B, the second straight portion 11C, the second curved portion 11D and the third straight portion 11E are tubular members having a predetermined inner diameter. Note that the first straight portion 11A, the first curved portion 11B, the second straight portion 11C, the second curved portion 11D and the third straight portion 11E do not necessarily have the same inner diameter, and may have different inner diameters. may Further, the first straight portion 11A, the second straight portion 11C and the third straight portion 11E do not necessarily have to be straight, and may be curved with a predetermined curvature. Also, the first curved portion 11B and the second curved portion 11D are central portions of the flow path in which the gas A bends. In addition, the first curved portion 11B and the second curved portion 11D may be the inner portion or the outer portion of the curved portion of the gas flow pipe 1 .

The first straight portion 11A supplies the gas A introduced from the gas introduction portion 10 to the first curved portion 11B. The first bending portion 11B bends with a continuously changing curvature RA1 following the relaxation curve. The first curved portion 11B curves, for example, with the curvature RA1 continuously increasing from the first straight portion 11A side to the second straight portion 11C side along the flow direction of the gas A from the upstream side to the downstream side. The flow direction here is, for example, the direction in which the gas A flows from the first straight portion 11A to the second straight portion 11C through the first curved portion 11B. As a result, the path of the gas A flowing through the first curved portion 11B changes continuously from the first straight portion 11A toward the second straight portion 11C, as in the example shown in FIG. 1A. As a result, on the same principle as the example shown in FIG. 1A, it is possible to suppress rapid changes in the course of the gas A passing through the first curved portion 11B, and the gas A is prevented from passing through the first curved portion 11B. resistance can be reduced.

The second straight portion 11C supplies the gas A supplied from the first curved portion 11B to the second curved portion 11D. The second curved portion 11D curves with a continuously changing curvature RA2 following the relaxation curve. The second curve 11D is curved, for example, with a curvature RA2 continuously increasing from the second straight portion 11C side to the third straight portion 11E side along the flow direction of the gas A from the upstream side to the downstream side. The flow direction here is, for example, the direction in which the gas A flows from the second straight portion 11C to the third straight portion 11E through the second curved portion 11D. As a result, the path of the gas A flowing through the second curved portion 11D changes continuously from the second straight portion 11C toward the third straight portion 11E, as in the example shown in FIG. 1A. As a result, on the same principle as the example shown in FIG. 1A, it is possible to suppress abrupt changes in the course of the gas A passing through the second curved portion 11D. An increase in resistance can be further reduced. The third straight portion 11E supplies the gas A supplied from the second curved portion 11D to an engine (not shown) or the like provided at a subsequent stage.

On the other hand, as shown in FIG. 3, the general gas circulation pipe 2, like the gas circulation pipe 1 shown in FIG. The first linear portion 21A, the first curved portion 21B, the second linear portion 21C, the second curved portion 21D and the third linear portion 21E, which are on the upstream side, flow in this order and are supplied to an engine or the like provided in the subsequent stage. The configurations of the first straight portion 21A, the second straight portion 21C, and the third straight portion 21E are the same as in the example shown in FIG. The first curved portion 21B has a constant curvature R from the first straight portion 21A side toward the second straight portion 21C side. This curvature R is constant from the first straight portion 21A toward the second straight portion 21C. Further, the second curved portion 21D has a constant curvature R from the second straight portion 21C side toward the third straight portion 21E side. This curvature R is constant from the second straight portion 21C toward the third straight portion 21E.

In such a gas flow tube 2, when the gas flowing from the first straight portion 21A flows through the first curved portion 21B, the course changes abruptly according to the curvature R1 of the first curved portion 21B. After maintaining a predetermined course, the course suddenly changes again and flows into the second straight portion 21C. Then, when the gas A flowing from the second straight portion 21C flows through the second curved portion 21D, the course changes abruptly according to the curvature R of the second curved portion 21D, and after maintaining a predetermined course, , the course changes again abruptly and flows into the second straight portion 21E.

As described above, in the general gas flow tube 2, the path of the gas A flowing through the first curved portion 21B and the second curved portion 21D changes rapidly. As a result, on the same principle as the example shown in FIG. 1B, the course of the gas A passing through the first curved portion 21B and the second curved portion 21D suddenly changes, and the first curved portion 21B and the second curved portion 21D can be reduced in resistance.

As described above, according to the above-described embodiment, the gas flow pipe 1 has the curvatures of the first curved portion 11B and the second curved portion 11D, through which the gas A flows, which are continuously changed by a transition curve such as a clothoid curve. do. Since the gas flow pipe 1 mitigates sudden changes in the path of the gas A when the fluid such as the gas A passing through the inside passes through the first curved portion 11B and the second curved portion 11D, It is possible to reduce the resistance increase due to the curved portion of the flowing fluid. In addition, since the gas circulation pipe 1 can reduce the increase in the resistance of the gas A without changing the pipe diameter, the rebounding of the fluid based on the first curved portion 11B and the second curved portion 11D in the fluid circulation pipe can be reduced. can be prevented. As a result, the gas circulation tube 1 can prevent, for example, the rebounding of the fluid flowing inside the gas circulation tube 1 from adversely affecting the acoustic effect. In particular, in the engine room of an automobile, where the arrangement and shape of the gas circulation pipe are restricted in the conventional gas circulation pipe, the curvature of the curved portion of the gas circulation pipe does not necessarily have to be adjusted even when the fuel-containing gas or the like flows inside. There were cases where the optimal range was not possible. On the other hand, according to the gas flow pipe 1, since the curved portion is provided that curves along the relaxation curve whose curvature changes continuously, the curved portion of the gas flow pipe when the fuel-containing gas passes through the curved portion It is also possible to solve the problem of increased resistance of the fuel-containing gas at . Since the gas circulation pipe 1 can reduce the increase in resistance of the fluid without changing the pipe diameter, the gas A based on the first curved portion 11B and the second curved portion 11D in the gas circulation pipe 1 can be reduced. It is possible to prevent rebounding of fluid such as. As a result, the gas circulation tube 1 can prevent adverse effects on the acoustic effect due to rebounding of the fluid such as the gas A flowing through the gas circulation tube 1, for example.

In addition, in the above-described embodiment, an example using the gas circulation pipe 1 for circulating the gas A as the fluid will be described, but the configuration is not limited to this. The fluid is not limited to the gas A, and any fluid substance such as a liquid can be applied as appropriate.

Moreover, in the above-described embodiment, an example of using a clothoid curve as a transition curve has been described, but it is also possible to use a transition curve other than a clothoid curve. Various relaxation curves can be applied as the relaxation curve. Even in this case, it is possible to obtain the same effect as the above-described embodiment.

Furthermore, in the embodiment described above, an example in which the gas flow pipe 1 includes the first curved portion 11B and the second curved portion 11D has been described, but the configuration is not limited to this. The gas flow tube may have one bend.

Further, in the above-described embodiment, an example in which the curvatures of the first curved portion 11B and the second curved portion 11D increase from the upstream side toward the downstream side in the flow direction of the gas A has been described. The curvatures of 11B and the second curved portion 11D are not limited to this configuration. The curvatures of the first curved portion 11B and the second curved portion 11D may be changed continuously. The curvature may decrease toward the downstream side.

In the above-described embodiment, the gas flow pipe 1 is not only an intake pipe such as an intake manifold that supplies fuel-containing gas to an internal combustion engine such as an engine, but also a gas exhaust pipe for fuel exhaust gas such as an exhaust manifold. It can also be used for various gas flow pipes.

(Example)
EXAMPLES Next, examples carried out to clarify the effects of the present invention will be described. The present invention is in no way limited by the following examples and comparative examples.

The present inventors used the gas circulation pipe shown in FIG. 2 according to the above-described embodiment and the general gas circulation pipe shown in FIG. A simulation test was performed. The details of the research conducted by the inventors will be described below.

FIG. 4 is a schematic diagram of a gas circulation tube according to an example of the present invention, and FIG. 5 is a schematic diagram of a gas circulation tube according to a comparative example of the invention. The configuration of the gas circulation tube 3 shown in FIG. 4 corresponds to the configuration of the gas circulation tube 1 shown in FIG. 2 described above, and the configuration of the gas circulation tube 4 shown in FIG. It corresponds to the configuration of tube 2 .

As shown in FIG. 4, in the gas flow tube 4 according to this embodiment, the curvatures of the first curved portion 31A and the second curved portion 31B continuously change, so that the first curved portion 31A and the second curved portion 31A There is no inflection point within 31B. As a result, in the gas flow pipe 3, the pressure generation point P1 generated by the air taken in from the air introduction portion 32 becomes the rear half portion of the curved portion 31A. As a result, it is possible to reduce ventilation resistance until the air introduced from the gas introducing portion 32 is discharged from the gas circulation pipe 3 .

On the other hand, in the gas flow pipe 4 according to the comparative example, since the curvatures of the first curved portion 41A and the second curved portion 41B are constant, the inside of the first curved portion 41A and the second curved portion 41B change. There are no inflection points. As a result, in the gas flow pipe 4, the pressure generation point P2 generated by the air taken in from the air introduction portion 42 becomes the front half of the first curved portion 51A compared to the pressure generation point P1 according to the above-described embodiment. As a result, the reduction in ventilation resistance for the air introduced from the gas introducing portion 42 to be discharged from the gas circulation pipe 4 is greatly increased. As a result, according to the gas circulation pipe 3 of the above embodiment, the ventilation resistance of the gas flowing through the gas circulation pipe 3 is improved by 1.45% as compared with the gas circulation pipe 4 of the comparative example. became possible.

FIG. 6 shows a case where the first curved portion 11B and the ^second curved portion 11D in FIG. The analysis result of the relationship between the bending diameter of the pipe and the pressure loss when the portion 21B and the second curved portion 21D are formed in an arc shape and air is introduced into the gas flow pipe 2 at a flow rate of 2.5 m ³ /min. Fig. 3 shows. FIG. 6 compares when the minimum diameter of the clothoid curve at the center of the first curved portion 11B and the second curved portion 11D is equal to the radius at the center of the first curved portion 21B and the second curved portion 21D.

FIG. 7 shows the results when the first curved portion 11B and the second curved portion 11D in FIG. 2 are formed into clothoid curves with a minimum diameter of 30 mm and air is introduced into the gas flow pipe 1 at a flow rate of 2.5 m ³ /min. FIG. 10 is a diagram showing the analysis result of the flow velocity at a position with color shading.

FIG. 8 shows the results when the first curved portion 11B and the second curved portion 11D in FIG. 2 are formed into clothoid curves with a minimum diameter of 45 mm and air is introduced into the gas flow tube 1 at a flow rate of 2.5 m ³ /min. FIG. 10 is a diagram showing analysis results of flow velocities at positions in shades of color;

FIG. 9 shows the results when the first curved portion 11B and the second curved portion 11D in FIG. 2 are formed into clothoid curves with a minimum diameter of 65 mm and air is introduced into the gas flow tube 1 at a flow rate of 2.5 m ³ /min. FIG. 10 is a diagram showing analysis results of flow velocities at positions in shades of color;

FIG. 10 shows the results at each position when the first curved portion 21B and the ^second curved portion 21D in FIG. It is the figure which represented the analysis result of the flow velocity with the light and shade of the color.

FIG. 11 shows the results at each position when the first curved portion 21B and the ^second curved portion 21D in FIG. It is the figure which represented the analysis result of the flow velocity with the light and shade of the color.

FIG. 12 shows the results at each position when the first curved portion 21B and the ^second curved portion 21D in FIG. It is the figure which represented the analysis result of the flow velocity with the light and shade of the color.

As shown in FIG. 6, when the first curved portion 11B and the second curved portion 11D were formed into clothoid curves with a minimum diameter of 30 mm, the first curved portion 21B and the second curved portion 21D were formed into arcs with a diameter of 30 mm. We were able to reduce the pressure loss by 9.1%. Further, when the first curved portion 11B and the second curved portion 11D are formed into clothoid curves with a minimum diameter of 45 mm, the pressure is greater than when the first curved portion 21B and the second curved portion 21D are formed into arcs with a diameter of 45 mm. Loss could be reduced by 10.8%. Further, when the first curved portion 11B and the second curved portion 11D are formed into clothoid curves with a minimum diameter of 65 mm, the pressure is greater than when the first curved portion 21B and the second curved portion 21D are formed into arcs with a diameter of 65 mm. Loss could be reduced by 13.0%.

As described above, at a relatively low flow rate, the first curved portion 11B and the second curved portion 11D formed in the clothoid curve are more pressure sensitive than the first curved portion 21B and the second curved portion 21D formed in the circular arc. It was confirmed that the loss could be reduced.

FIG. 13 shows a case where the first curved portion 11B and the ^second curved portion 11D in FIG. The analysis result of the relationship between the bending diameter of the pipe and the pressure loss when the portion 21B and the second curved portion 21D are formed in an arc and air is introduced into the gas flow pipe 2 at a flow rate of 4.0 m ³ /min. Fig. 3 shows. FIG. 13 also compares when the minimum diameter of the clothoid curve at the center of the first curved portion 11B and the second curved portion 11D is equal to the radius at the center of the first curved portion 21B and the second curved portion 21D.

FIG. 14 shows the results when the first curved portion 11B and the second curved portion 11D in FIG. 2 are formed into clothoid curves with a minimum diameter of 30 mm and air is introduced into the gas flow tube 1 at a flow rate of 4.0 m ³ /min. FIG. 10 is a diagram showing analysis results of flow velocities at positions in shades of color;

FIG. 15 shows the results when the first curved portion 11B and the second curved portion 11D in FIG. 2 are formed into clothoid curves with a minimum diameter of 45 mm and air is introduced into the gas flow tube 1 at a flow rate of 4.0 m ³ /min. FIG. 10 is a diagram showing analysis results of flow velocities at positions in shades of color;

FIG. 16 shows the results when the first curved portion 11B and the second curved portion 11D in FIG. 2 are formed into clothoid curves with a minimum diameter of 65 mm and air is introduced into the gas flow tube 1 at a flow rate of 4.0 m ³ /min. FIG. 10 is a diagram showing analysis results of flow velocities at positions in shades of color;

FIG. 17 shows the results at each position when the first curved portion 21B and the ^second curved portion 21D in FIG. It is the figure which represented the analysis result of the flow velocity with the light and shade of the color.

FIG. 18 shows the results at each position when the first curved portion 21B and the ^second curved portion 21D in FIG. It is the figure which represented the analysis result of the flow velocity with the light and shade of the color.

FIG. 19 shows the results at each position when the first curved portion 21B and the ^second curved portion 21D in FIG. It is the figure which represented the analysis result of the flow velocity with the light and shade of the color.

As shown in FIG. 13, when the first curved portion 11B and the second curved portion 11D were formed into clothoid curves with a minimum diameter of 30 mm, the first curved portion 21B and the second curved portion 21D were formed into arcs with a diameter of 30 mm. We were able to reduce the pressure loss by 11.2%. Further, when the first curved portion 11B and the second curved portion 11D are formed into clothoid curves with a minimum diameter of 45 mm, the pressure is greater than when the first curved portion 21B and the second curved portion 21D are formed into arcs with a diameter of 45 mm. Loss could be reduced by 10.5%. Further, when the first curved portion 11B and the second curved portion 11D are formed into clothoid curves with a minimum diameter of 65 mm, the pressure is greater than when the first curved portion 21B and the second curved portion 21D are formed into arcs with a diameter of 65 mm. Loss could be reduced by 13.5%.

Even at a relatively high flow rate as described above, forming the first curved portion 11B and the second curved portion 11D into a clothoid curve is better than forming the first curved portion 21B and the second curved portion 21D into an arc. It was confirmed that the pressure loss could be reduced.

1, 2, 3, 4 gas flow pipe 10 gas introducing portion 11A, 21A first straight portion 11B, 21B, 31A, 41A first curved portion 11C, 21C second straight portion 11D, 21D, 31B, 41B second curved portion 11E, 21E Third straight portion 101 Motorway 101A Straight portion 101B, 101C Curved portion 101D Maximum portion 102 Automobile 103 Handle R, RA, RA1, RA2 Curvature

Claims (1)

It has a first curved portion, a straight portion extending from the first curved portion, and a second curved portion extending from the straight portion along the flow direction of the fluid, and the first curved portion and the straight portion , and the second curved portion have the same diameter,
the first curved portion curves at its center along a clothoid curve whose curvature continuously decreases in the direction of flow of the fluid;
The intake manifold for an automobile, wherein the second curved portion curves at its center along a clothoid curve whose curvature continuously increases in the flow direction of the fluid.

Images