JP2006125207A - Heat insulating structure for exhaust pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat insulating structure for an exhaust pipe at low cost without requiring a die at the time of manufacturing. <P>SOLUTION: This heat insulating structure for the exhaust pipe consists of heat insulating material 2 covering an outer circumference of the exhaust pipe 1, a flexible protector 6 constructed by braiding to form a cylindrical shape by a bundle of metal wire material 5 (heat resistant wire) crossing with forming a spiral in reverse directions each other and covering an outer circumference of the heat insulating material 2, and a band 7 fixing plural parts in a longitudinal direction of the flexible protector 6 by being fastened in a circumference direction of the exhaust pipe 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust pipe heat insulating structure.

  Particulate matter (particulate matter) discharged from a diesel engine is mainly composed of soot composed of carbonaceous matter and SOF content (Soluble Organic Fraction) composed of high-boiling hydrocarbon components. Although it has a composition containing a small amount of sulfate (mist-like sulfuric acid component), as a measure to reduce this kind of particulates, a particulate filter is installed in the middle of the exhaust passage through which exhaust gas flows. Has been performed conventionally.

  This type of particulate filter has a porous honeycomb structure made of a ceramic such as cordierite, and the inlets of the flow paths partitioned in a lattice pattern are alternately sealed, and the inlets are not sealed. About the flow path, the exit is sealed, and only the exhaust gas which permeate | transmitted the porous thin wall which divides each flow path is discharged | emitted downstream.

  Then, the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, so that the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging. Although it is necessary to regenerate, there are few opportunities to obtain an exhaust temperature high enough to cause the particulates to self-combust under normal diesel engine operation conditions. It has been studied to adopt a catalyst regeneration type particulate filter in which an oxidation catalyst is arranged separately in the previous stage of the particulate filter.

  That is, if such a catalyst regeneration type particulate filter is employed, the oxidation reaction of the collected particulates is promoted to lower the ignition temperature, and the particulates can be burned and removed even at a relatively low exhaust temperature. It becomes possible.

  In addition to the particulate filter described above, it has also been proposed to equip the exhaust passage with a NOx selective reduction catalyst or NOx occlusion reduction catalyst for the purpose of removing NOx in the exhaust gas as a post-treatment device. Particularly in recent years, an aftertreatment device in which a particulate filter is combined with a NOx storage reduction catalyst has been developed.

  However, even if any of these after-treatment devices is adopted, a relatively high exhaust temperature higher than a predetermined temperature is required in order to obtain reliable combustion removal of particulates and sufficient catalytic activity. It is important to introduce the exhaust gas into the aftertreatment device before the temperature of the exhaust gas discharged from the engine is lowered as much as possible.

  When installing this type of aftertreatment device on a vehicle, depending on the vehicle model, there are cases in which the space for installing the aftertreatment device can be secured only at a position away from the diesel engine. When the outside air temperature is low, the exhaust temperature tends to decrease while the exhaust gas is led from the diesel engine to the aftertreatment device through the exhaust pipe, and there is a concern that the operating region in which the aftertreatment device is active becomes narrower than usual. .

  For example, as a measure for preventing such a decrease in the exhaust temperature, as shown in FIGS. 6 and 7, a glass wool molded product is attached to the outer peripheral portion of the exhaust pipe 1 as the heat insulating material 2, and a pair of the outside of the heat insulating material 2 is paired. A heat insulation structure has been proposed in which the half covers 3 and 3 are fitted and fastened with bolts and nuts 4.

In addition, the heat insulation structure of this kind of exhaust pipe 1 uses the existing structure conventionally known as a soundproofing measure of the exhaust pipe 1, and prior art document information related to such an existing structure is as follows. There exists patent document 1 grade | etc.,.
Japanese Utility Model Publication No. 3-1226

  In the heat insulation structure of FIGS. 6 and 7 as described above, considering that the application site is a high temperature condition, the half covers 3 and 3 covering the heat insulating material 2 are manufactured as sheet metal drawn products. However, because the layout restrictions differ greatly depending on the vehicle type, it is difficult to make the exhaust pipes common. Therefore, it is necessary to newly create a mold with a half cover for each vehicle type, and the mold cost is reduced. There is a problem that it is bulky and causes a significant cost increase.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat insulating structure for an exhaust pipe that can be realized at a low cost without requiring a mold at the time of production.

  According to the present invention, a blade is knitted so as to form a cylindrical shape by a bundle of heat insulating materials coated on the outer peripheral portion of an exhaust pipe and heat-resistant wire rods that cross in a mutually opposite spiral shape, An exhaust pipe heat retention structure comprising a flexible protector placed on an outer peripheral portion and a band for fastening and fixing a plurality of longitudinal locations of the flexible protector in the circumferential direction of the exhaust pipe. Is.

  Thus, by compressing the flexible protector in the axial direction, the rhomboid stitch of the flexible protector is flattened and the diameter of the flexible protector is expanded. It becomes easy to cover the heat insulating material coated on the outer peripheral portion of the exhaust pipe with the flexible protector, and further, when the flexible protector is extended in the axial direction after being covered with the heat insulating material, the flexible protector The diamond-shaped stitch is stretched in the axial direction and the diameter of the flexible protector is reduced, so that the heat insulating material is tightly pressed against the exhaust pipe by the flexible protector and the exhaust pipe is bent. It fits snugly and a good wearing state is obtained, and such a good wearing state is maintained by fixing with the band.

  Moreover, in this invention, it is preferable to provide the protective cover which coat | covered the terminal of a flexible protector and was fixed to the outer peripheral part of an exhaust pipe, and, if it does in this way, the terminal of the flexible protector in the state where it rolled up Is covered with a protective cover, so that the operator's fingertips and the like can be prevented from being damaged by the end of the flexible protector when the exhaust pipe is assembled or inspected.

  According to the exhaust pipe heat insulation structure of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the heat insulating material can be tightly pressed and closely aligned with various bent exhaust pipes using a flexible protector. Thus, a half cover made of a sheet metal drawing product as in the prior art is not required, and the cost required for the mold can be greatly reduced, and an exhaust pipe heat insulation structure can be realized at a low cost.

  (II) According to the invention described in claim 2 of the present invention, since the terminal of the flexible protector that has been raised can be covered with the protective cover, the operator can install the exhaust pipe during inspection and inspection. It is possible to avoid a possibility that a fingertip or the like may be damaged by the tip of the flexible protector terminal.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 show an example of an embodiment for carrying out the present invention, and portions denoted by the same reference numerals as those in FIGS. 6 and 7 represent the same items.

  In this embodiment, the outer peripheral portion of the exhaust pipe 1 is coated with glass wool on aluminum foil as a heat insulating material 2, and the outer side of the heat insulating material 2 has a spiral shape opposite to each other. A flexible protector 6 braided so as to form a cylindrical shape is covered with a bundle of metal wires 5 that cross each other (see FIG. 3), and the flexible protector 6 has a plurality of locations in the longitudinal direction (two in the illustrated example). A portion) is fastened and fixed in the circumferential direction of the exhaust pipe 1 by a band 7.

  Here, the metal wire 5 for braiding the flexible protector 6 is not necessarily limited to being made of metal as long as it is a heat-resistant wire. For example, the flexible protector 6 is obtained by braiding glass fiber. It is also possible.

  As for the heat insulating material 2, a glass wool molded product may be used as in the conventional case, but if glass wool is pasted on an aluminum foil, water absorption to the glass wool is blocked by the aluminum foil and unintended corrosion conditions. It is possible to avoid establishment.

  Thus, if the heat insulation structure of the exhaust pipe 1 is configured in this way, the rhomboid stitches of the flexible protector 6 can be flattened by compressing the flexible protector 6 in the axial direction. Since the diameter of the flexible protector 6 is expanded, the flexible protector 6 can be easily covered with the heat insulating material 2 covered on the outer peripheral portion of the exhaust pipe 1.

  Further, when the flexible protector 6 is stretched in the axial direction after being covered with the heat insulating material 2, the rhomboid stitches of the flexible protector 6 are stretched in the axial direction so that the flexible protector 6 Since the diameter is reduced, the heat-insulating material 2 is tightly pressed against the exhaust pipe 1 by the flexible protector 6 and is closely aligned with the bent shape of the exhaust pipe 1 to obtain a good mounting state. Such a good wearing state is maintained by fixing with the band 7.

  Therefore, according to the above-described embodiment, the heat insulating material 2 can be tightly pressed and closely aligned with the bent exhaust pipe 1 using the flexible protector 6, so that the conventional sheet metal can be used. This eliminates the need for a half-cut cover made of a drawn product, and can greatly reduce the cost of the mold, and the heat insulation structure of the exhaust pipe 1 can be realized at a low cost.

  4 and 5 show another embodiment of the present invention. In this embodiment, a protective cover 8 that covers the end of the flexible protector 6 and is fixed to the outer peripheral portion of the exhaust pipe 1 is provided. In the example shown here, the protective cover 8 has a bell mouth shape in which one end is narrowed to an inner diameter substantially matching the outer diameter of the exhaust pipe 1 and the other end is gradually expanded. Therefore, the protective cover 8 is moved in the axial direction of the exhaust pipe 1 and the end of the flexible protector 6 is inserted into the other end of the bell mouth. The side is fixed to the exhaust pipe 1 by welding.

  Thus, since the terminal of the flexible protector 6 in the state of being rolled up can be covered with the protective cover 8, the operator's fingertip or the like can be used when the exhaust pipe 1 is assembled or inspected. It is possible to avoid the possibility that the flexible protector 6 will be damaged by the tip of the terminal of the flexible protector 6.

  In addition, the exhaust pipe heat insulation structure of the present invention is not limited to the above-described embodiment, and the material of the heat-resistant wire and the heat insulating material is not limited to those illustrated in the embodiment, and the protective cover includes Of course, shapes other than those shown in the drawings may be adopted, and various modifications may be made without departing from the scope of the present invention.

It is a top view which shows an example of the form which implements this invention. It is sectional drawing of the II-II arrow of FIG. It is an enlarged view which shows the detail of the stitch of the flexible protector of FIG. It is a top view which shows another example of a form of this invention. It is sectional drawing of the VV arrow of FIG. It is a top view which shows a prior art example. It is sectional drawing of the VII-VII arrow of FIG.

Explanation of symbols

1 Exhaust pipe 2 Heat insulation material 5 Metal wire (heat-resistant wire)
6 Flexible protector 7 Band 8 Protective cover

Claims (2)

  The heat insulating material coated on the outer peripheral portion of the exhaust pipe and the heat-resistant wire bundle that crosses in a mutually opposite spiral shape are braided so as to form a cylindrical shape and cover the outer peripheral portion of the heat insulating material. An exhaust pipe heat insulation structure comprising: the flexible protector formed and a band that fastens and fixes a plurality of longitudinal positions of the flexible protector in a circumferential direction of the exhaust pipe.   The exhaust pipe heat insulation structure according to claim 1, further comprising a protective cover that covers a terminal of the flexible protector and is fixed to an outer peripheral portion of the exhaust pipe.

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