JP2004300940A - Double tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable circulation of cooling water without needing a connector when a double tube is utilized as EGR piping and improve cooling efficiency. <P>SOLUTION: Partition walls 28a to 25d to partition a space part formed between an inner tube 24 and an outer tube 26 into a plurality of passages are formed integrally with the inner tube 24 and the outer tube 26. Intercommunication holes 31 through which the passages are intercommunicated are formed in the positions of the terminal end parts of the double tube. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a double pipe, and more particularly, to a double pipe used as a cooling pipe in an exhaust gas recirculation device for an engine (hereinafter, referred to as an EGR device).
[0002]
[Prior art]
The EGR device is a device that recirculates a part of exhaust gas from an engine to an intake system, suppresses a combustion temperature and reduces NOx emissions, and connects an exhaust manifold and an intake manifold with an EGR pipe to form an exhaust gas. Is introduced into the intake manifold. In addition, EGR devices are increasing in number of cases for the purpose of reducing pumping loss.
[0003]
Conventionally, stainless steel piping has been used for EGR piping, and has a double structure of an outer tube and an inner tube in order to prevent erosion of a resin intake manifold and heat damage in an engine room. In some cases, tubes are used.
[0004]
Therefore, a conventional double pipe used for the EGR pipe is shown in FIG. In FIG. 8, reference numeral 2 denotes an outer tube. Inside the outer tube 2, an inner tube 4 is accommodated concentrically. Between the inner peripheral surface of the outer tube 2 and the outer peripheral surface of the inner tube 4, there is formed an annular space which serves as a cooling water passage over the entire length of the double tube. Flanges 6a and 6b are integrally formed at both ends of the double pipe. Connectors 7a and 7b are provided at both ends of the double pipe.
[0005]
The connector 7a is connected to a tube for introducing cooling water into the annular space, and the connector 7b is connected to a tube for drawing cooling water from the annular space.
[0006]
[Problems to be solved by the invention]
However, since the double pipe used for the EGR pipe has a structure in which the connectors 7a and 7b are fixed by brazing, there is a disadvantage that the number of manufacturing steps increases and the cost increases.
[0007]
When a double pipe is used for EGR, it must be bent in accordance with the shape of the engine. However, the conventional double pipe has a drawback that if the bending is large, the pipe is crushed.
In view of the above, an object of the present invention is to solve the above-described problems of the related art, and when using it as an EGR pipe, it is possible to circulate cooling water without using connectors and to improve cooling efficiency. The object is to provide a double tube.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a double pipe having a concentric double structure of an inner pipe and an outer pipe, wherein a space formed between the inner pipe and the outer pipe has a plurality of passages. A plurality of partition walls are formed integrally with the inner pipe and the outer pipe, and a communication hole is formed in the partition wall at a position of an end portion of the double pipe to allow passages to communicate with each other. .
[0009]
According to the present invention, the inner pipe and the outer pipe have a double pipe structure connected by a partition, and the partition divides a passage for circulating cooling water. Strength can be increased.
[0010]
Further, the present invention provides a double pipe having a concentric double structure of an inner pipe and an outer pipe, wherein a plurality of partition walls for partitioning a space formed between the inner pipe and the outer pipe into a plurality of passages. A double-pipe main body formed integrally with the inner pipe and the outer pipe and having a communication hole for communicating the passages with the partition at the end of the double pipe, and an inlet for introducing a cooling medium into the passages A hole having an outlet hole for leading a cooling medium from the passage, and a flange portion connectable to a valve body of a water-cooled EGR valve for opening and closing a flow path for recirculating exhaust gas in an EGR device of the engine. The flange portion is characterized in that cooling water is introduced from an EGR valve into an inlet hole thereof and connected to the EGR valve through an outlet hole so that the cooling water can be recirculated to the EGR valve.
[0011]
According to the present invention, only by connecting the double pipe to the EGR valve to use it as the EGR pipe, a part of the cooling water supplied to the EGR valve is introduced from the flange portion and circulated in the EGR pipe. Therefore, parts such as tubes and connectors for cooling water circulation can be eliminated from the EGR pipe.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a double pipe according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an EGR device of an engine to which a double pipe according to the present embodiment is applied. In FIG. 1, reference numeral 10 indicates an engine. 12 is an intake manifold and 14 is an exhaust manifold. From the exhaust manifold 14, an EGR pipe 16a for recirculating a part of the exhaust gas to the intake manifold 12 branches, and an EGR valve 17 for opening and closing the pipe line and controlling the flow rate of the recirculated exhaust gas is connected to the EGR pipe 16a. Have been. Further, an EGR pipe 16 b is used as a pipe connecting the EGR valve 17 and the intake manifold 12, and an end of the EGR pipe 16 b is connected to the intake manifold 12. The operation of the EGR valve 17 is controlled by an electronic control unit (ECU) 20.
[0013]
2 and 3 show a double tube according to the present embodiment. The double pipe 22 is a double pipe in which two pipes of an inner pipe 24 and an outer pipe 26 are concentrically integrated. In this embodiment, the double pipe 22 is an aluminum or aluminum alloy double pipe formed by extrusion.
When used as the EGR pipe 16b, the inside of the inner pipe 24 serves as a passage for exhaust gas, and the annular space formed between the inner pipe 24 and the outer pipe 26 is used as a passage for cooling water for cooling the exhaust gas. Have been.
[0014]
In this embodiment, as shown in FIG. 4, the annular space formed between the inner pipe 24 and the outer pipe 26 is divided into four passages 30a to 30d by four partition walls 28a to 28d located symmetrically at 90 ° with respect to the center. 30d is sectioned. Of these passages 30a to 30d, the passages 30a and 30b are passages serving as the outward passage of the cooling water, and the passages 30c and 30d are passages serving as the return passage of the cooling water. At the end of the double pipe, as shown in FIG. 5, a communication hole 31 is formed in the partition wall 28b and the partition wall 28d to connect the outward path and the return path.
[0015]
A first flange member 32 and a second flange member 34 are fixed to both ends of the double pipe 22, respectively. The first flange member 32 has a hole having a diameter substantially equal to the inner diameter of the inner tube 24. The first flange member 32 on the inlet side has an inlet for introducing cooling water into the passages 30a and 30b. A hole 36 and an outlet hole 38 for leading cooling water from the passages 30c and 30d are formed. The second flange member 34 has a hole having a diameter substantially equal to the outer diameter of the outer tube 26 so that the second flange member 34 can be fitted to the outer tube 26.
[0016]
In FIG. 6, in the EGR valve 17, it is necessary to cool the EGR valve so that the stepping motor for driving the valve element receives the heat of the exhaust gas and raises the temperature so that the control accuracy of the opening degree of the valve element does not decrease. For this reason, a cooling water tube 37 for supplying cooling water and a drain tube 39 for discharging cooling water are connected to the EGR valve 17.
[0017]
As shown in FIG. 6, a cooling water supply tube 37 and a cooling water discharge tube 39 are connected to a valve body 41 of the EGR valve 17, and cooling water passages 40 and 44 are formed therein. The cooling water introduced from the cooling water supply tube 37 cools the valve body 41 while flowing through the cooling water passage 40, and is sent to the EGR pipe 16b as described later.
[0018]
The left and right side surfaces of the EGR valve 17 are connecting portions between the EGR pipe 16a and the EGR pipe 16b. A first communication hole 42 opening as an outlet of the cooling water passage 40 and a second communication hole 43 opening as an inlet of the cooling water passage 44 are formed at a connection portion of the EGR valve 17 with the EGR pipe 16b. . When the first flange member 32 and the second flange member 34 of the EGR pipe 16b are fastened and fixed to the side surface of the EGR valve 17, the first communication hole 42 on the EGR valve 17 side and the inlet hole 36 on the EGR pipe 16b overlap and The second communication hole 43 and the outlet hole 38 overlap.
[0019]
The double tube according to the present embodiment is configured as described above. Next, the operation and effects will be described.
While the engine 10 is operating, the electronic control unit 20 opens the EGR valve 17 at a predetermined opening degree, and a part of the exhaust gas flowing through the exhaust manifold 14 is transferred from the EGR pipe 16a to the double pipe 22 forming the EGR pipe 16b. And flows back to the intake manifold 12.
[0020]
As shown in FIG. 6, the cooling water supplied from the cooling water supply tube 37 connected to the EGR valve 17 cools the valve body 41 while flowing through the cooling water passage 40. Further, the cooling water flowing through the cooling water passage 40 inside the valve body 41 is transferred to the outward passages 30 a and 30 b defined between the inner pipe 24 and the outer pipe 26 via the first communication hole 42 and the inlet hole 36. be introduced. In FIG. 5, the cooling water flowing through the passages 30a and 30b flows into the return passages 30c and 30d from the communication hole 31 at the opposite pipe end to reverse the flow, and the cooling water flows through the return passages 30c and 30d as they are. It flows back to the cooling water passage 44 inside the EGR valve 17 through the outlet hole 38 and the second communication hole 43, and is discharged from the cooling water discharge tube 39. As the cooling water circulates through the double pipe 22 used as the EGR pipe 16b in this manner, the exhaust gas flowing through the inner pipe 24 is efficiently cooled, and the exhaust gas having a lowered temperature is returned to the intake manifold 12.
[0021]
According to the present embodiment in which the double pipe 22 of the present invention is applied to the EGR pipe 17, a part of the cooling water supplied to the EGR valve 17 is introduced simply by connecting the EGR pipe 17 to the EGR pipe 16b. Since the inside can be circulated, components such as tubes and connectors for cooling water circulation are not required in the EGR pipe 16b.
[0022]
Further, since the inner pipe 24 for flowing exhaust gas and the outer pipe 26 have a double pipe structure connected by partitions 28a to 28d, and the partitions 30a to 30d divide the passages 30a to 30d for circulating cooling water, The cooling efficiency is high, and the strength can be increased. In addition, the double tube having such a structure can be easily manufactured by extrusion molding an aluminum alloy as a material.
[0023]
Here, FIG. 7 is a cross-sectional view showing a modified example of the double pipe. In the double pipe according to the above-described embodiment, the passages 30a to 30d are partitioned by four partition walls. FIG. 7A is a double pipe in which the passages 51a and 51b are partitioned by two partition walls 50. (B) is a double pipe in which passages 53a to 53f are partitioned by six partition walls 52. As described above, it is easy to make the number of passage sections by the partition walls an appropriate number in the case of extrusion molding.
[0024]
【The invention's effect】
As is clear from the above description, according to the present invention, when used as an EGR pipe, the cooling water can be circulated without the need for connectors, and the cooling efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an EGR system of an engine to which a double pipe according to the present invention is applied.
FIG. 2 is an exploded view of a double pipe according to an embodiment of the present invention.
FIG. 3 is a perspective view of a double pipe according to an embodiment of the present invention.
FIG. 4 is a view showing a section taken along line IV-IV in FIG. 3;
FIG. 5 is a perspective view showing a shape of a pipe end of the double pipe.
FIG. 6 is a diagram showing a connection structure between an EGR valve and a double pipe.
FIG. 7 is a cross-sectional view showing another modified example of the double pipe according to the present invention.
FIG. 8 is a perspective view showing a conventional double pipe.
[Explanation of symbols]
10 Engine 12 Intake manifold 14 Exhaust manifold 16a, 16b EGR pipe 17 EGR valve 20 Electronic control unit 22 Double pipe 24 Inner pipe 26 Outer pipe 36 Inlet hole 38 Outlet hole

Claims (5)

In a double pipe having a concentric double structure of an inner pipe and an outer pipe,
A plurality of partitions partitioning a space formed between the inner pipe and the outer pipe into a plurality of passages are formed integrally with the inner pipe and the outer pipe, and the partition is formed at a position of an end of the double pipe. A double hole formed with a communication hole for connecting the passages to each other. A flange member is attached to an end of the double pipe, and an inlet hole for introducing a cooling medium into the passage and an outlet hole for leading a cooling medium from the passage are formed in the flange member. 2. The double tube according to 1. The double pipe according to claim 2, wherein the inlet hole and the outlet hole are formed in the same flange member attached to the end of the double pipe on which the communication hole is not formed. The double pipe according to any one of claims 1 to 3, wherein the double pipe is made of aluminum or an aluminum alloy formed by extrusion. In a double pipe having a concentric double structure of an inner pipe and an outer pipe,
A plurality of partitions partitioning a space formed between the inner pipe and the outer pipe into a plurality of passages are formed integrally with the inner pipe and the outer pipe, and the partition is formed at a position of an end of the double pipe. A double pipe body formed with a communication hole for communicating the passages with each other;
An inlet hole for introducing a cooling medium into the passage, and an outlet hole for leading the cooling medium from the passage, and connected to a valve body of a water-cooled EGR valve for opening and closing a flow path for recirculating exhaust gas in an EGR device of an engine. And a possible flange,
The double pipe is characterized in that the flange portion is configured to introduce cooling water from an EGR valve into an inlet hole and to connect the cooling water to an EGR valve from an outlet hole so as to be recirculated.

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