JP2005325691A - Urea solution supply pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize antifreezing measures of a urea solution supply pipe for leading urea solution as a reducing agent to a selective reduction type catalyst at minimum cost. <P>SOLUTION: With respect to a urea solution supply pipe for leading urea solution as a reducing agent to a selective reduction type catalyst, an electric heater 2 is arranged along the outer peripheral part of a pipe body 1. The electric heater 2 is covered together with the pipe body 1 with a plain weave mesh 4 woven so as to form a cylindrical form by glass wool 3 (fibrous material) intersecting in spiral shapes directed in mutually opposed directions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a urea water supply pipe that guides urea water as a reducing agent to a selective reduction catalyst for reducing and purifying NOx.

  Conventionally, diesel engines are equipped with a selective reduction catalyst (selective reduction catalyst) that has the property of selectively reacting NOx with a reducing agent even in the presence of oxygen in the middle of an exhaust pipe through which exhaust gas flows. The required amount of reducing agent is added to the upstream side of the selective catalytic reduction catalyst, and the reducing agent is subjected to a reduction reaction with NOx (nitrogen oxide) in the exhaust gas on the selective catalytic reduction catalyst, whereby NOx emission concentration There is one that can reduce the above.

On the other hand, in the field of industrial flue gas denitration treatment in plants and the like, the effectiveness of a method for reducing and purifying NOx using ammonia (NH ₃ ) as a reducing agent is already widely known. Since it is difficult to ensure safety with respect to traveling with ammonia itself, in recent years, the use of non-toxic urea water as a reducing agent has been studied (see, for example, Patent Document 1). .
JP 2002-161732 A

  That is, if urea water is added to the exhaust gas upstream of the selective catalytic reduction catalyst, the urea water is decomposed into ammonia and carbon dioxide under a temperature condition of about 170 ° C. or higher, and the exhaust gas is exhausted on the selective catalytic reduction catalyst. The NOx contained therein is reduced and purified well by ammonia.

  When urea water is used as a reducing agent in this manner, urea water is sent from the storage tank mounted on the vehicle to the upstream side of the selective catalytic reduction catalyst via the urea water supply pipe. Since it freezes at 13.5 degrees C or less, when using in a cold region, it is necessary to take some measures against freezing so that the urea water supply pipe is not blocked by freezing of urea water.

  Therefore, conventionally, a urea water supply pipe in which the electric heater a as shown in FIG. 9 is embedded in the tube body portion of the pipe main body b is adopted, and when necessary, the electric heater a is energized to generate heat. The urea water frozen in the pipe body b can be thawed.

  Although it is not unthinkable to pass the electric heater a through the internal flow path of the pipe body b, there is a concern that the electric heater a may be eroded by exposure to the flow of urea water, leading to electric leakage. The fact is that the adoption has been postponed for safety reasons.

  However, when manufacturing a urea water supply pipe in which the electric heater a as shown in FIG. 9 is embedded in the pipe wall portion, the die of the urea water supply pipe must be modified, and it is −13.5 ° C. or less. However, there is a problem that expensive capital investment is required for a small number of vehicles subject to cold district specifications that must be assumed to have a low temperature.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to realize a measure for freezing a urea water supply pipe that guides urea water as a reducing agent to a selective catalytic reduction catalyst at as low a cost as possible. .

  The invention according to claim 1 of the present invention is a urea water supply pipe for guiding urea water as a reducing agent to the selective catalytic reduction catalyst, and an electric heater is arranged along the outer peripheral portion of the pipe main body, and is mutually opposite. The electric heater is covered with the tube main body by a plain weave mesh that is woven so as to form a cylindrical shape with fiber materials that intersect in a spiral shape.

  Thus, when such a plain weave mesh is compressed in the axial direction, the weave formed by the weft and warp of the fiber material is flattened and the diameter of the plain weave mesh is expanded. If it can be covered without difficulty, and then stretched in the axial direction, the diamond-shaped weave is stretched in the axial direction to reduce the diameter of the plain weave mesh, and the plain weave mesh is tightly attached to the pipe body. The electric heater is mounted and fixed well.

  The invention according to claim 2 of the present invention relates to a similar urea water supply pipe, and is made of a fiber material so as to form an endless stitch of a chain shape by arranging an electric heater along the outer peripheral portion of the pipe body. The electric heater is covered with the tube main body by a knitted knitted mesh.

  In this way, since the knit knitted mesh has elasticity, the knit knitted mesh is formed in advance with a diameter smaller than the outer diameter of the pipe main body, and this is piped on the pipe main body along with the electric heater. When covering with the mouth widened, the knit knitted mesh is tightly attached to the pipe body by its own restoring force, and the electric heater is fixed well.

  Further, the invention according to claim 3 of the present invention relates to a similar urea water supply pipe, and an electric heater is arranged along the outer peripheral portion of the pipe body, and the electric heater is put together with the pipe body by a film formed by dip molding. The invention according to claim 4 of the present invention is a film formed by coating instead of the dip molding, but can be easily formed in any case. The electric heater is satisfactorily fixed by the coating.

  The invention according to claim 5 of the present invention relates to a similar urea water supply pipe, wherein an electric heater is disposed along the outer periphery of the pipe body, and the electric heater is covered with the pipe body by a heat shrinkable tube. It is characterized by.

  In this way, when the heat-shrinkable tube is formed in advance with a diameter larger than the outer diameter of the tube body, and this is put on the tube body along with the electric heater and heated, the heat-shrinkable tube contracts and the tube It is closely attached to the outer peripheral portion of the main body, and the electric heater is satisfactorily fixed to the outer peripheral portion of the tube main body.

  According to the urea water supply pipe of the present invention described above, the electric heater along the outer peripheral portion of the pipe body is covered with any one of a plain weave mesh, a knit knitted mesh, a dip-formed or coated film, and a heat-shrinkable tube. Since it can be fixed well without the need for mold processing, it is possible to avoid costly mold remodeling as in the case of manufacturing a urea water supply pipe in which an electric heater is embedded in the conventional pipe wall part, It is possible to achieve an excellent effect that the countermeasure for freezing the urea water supply pipe can be realized at as low a cost as possible.

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

  1 to 3 show a first embodiment of the present invention. In the example shown here, a pipe main body 1 relates to a urea water supply pipe that leads urea water to a selective catalytic reduction catalyst as a reducing agent. A plain weave mesh 4 (see FIG. 2) which is laid in a cylindrical shape with glass wool 3 (fiber material) which is arranged along the outer peripheral portion of the glass heater 3 along the opposite sides of each other in a spiral shape opposite to each other. ), The electric heater 2 is covered with the pipe body 1 together.

  That is, as shown in FIG. 3, when such a plain weave mesh 4 is compressed in the axial direction, the weave formed by the weft and the warp of the glass wool 3 is flattened and the diameter of the plain weave mesh 4 is expanded. The plain weave mesh 4 can be comfortably covered on the pipe body 1 and then stretched in the axial direction as shown in FIG. 1 so that the diamond-shaped weave is stretched in the axial direction so that the diameter of the plain weave mesh 4 is increased. Is reduced, and the plain weave mesh 4 is tightly attached to the tube body 1 so that the electric heater 2 is fixed well.

  In particular, as in this embodiment, when glass wool 3 is used as the fiber material of the plain weave mesh 4, the heat of the electric heater 2 is difficult to escape outside the tube due to the heat insulating performance of the glass wool 3, and it freezes in the tube. It is possible to enhance the function of thawing the urea water.

  Therefore, according to the first embodiment, it is possible to fix the electric heater 2 along the outer peripheral portion of the pipe body 1 by simply covering the electric heater 2 with the plain weave mesh 4 made of glass wool 3, so that This makes it possible to avoid costly mold remodeling as in the case of manufacturing a urea water supply pipe with the electric heater 2 embedded in the pipe wall portion, and to realize a countermeasure for freezing of the urea water supply pipe at a low cost. it can.

  4 to 6 show a second embodiment of the present invention. In this embodiment, the electric heater 2 along the outer periphery of the tube body 1 is formed into a chain-shaped endless stitch. The tube body 1 is covered with a knit mesh 5 (see FIG. 5) knitted with glass wool 3 (fiber material).

  Thus, since the knit knitted mesh 5 has elasticity in this way, the knit knitted mesh 5 is formed in advance with a diameter smaller than the outer diameter of the tube body 1 as shown in FIG. When this is put on the tube main body 1 along with the electric heater 2 while expanding the tube opening, the knit knitted mesh 5 is tightly attached to the tube main body 1 by its own restoring force, and the electric heater 2 is fixed well. It will be.

  Therefore, according to such a second embodiment, the electric heater 2 along the outer periphery of the tube body 1 can be satisfactorily fixed simply by covering it with the knit knitted mesh 5 made of glass wool 3. Similar to the case of the first embodiment described above, it is possible to avoid costly mold remodeling as in the case of manufacturing a urea water supply pipe in which the electric heater 2 is embedded in the conventional pipe wall portion. Countermeasures against freezing of the supply pipe can be realized at low cost.

  In this embodiment, the reason why the glass wool 3 is used as the fiber material constituting the knit knitted mesh 5 is the same as that in the case of the plain weave mesh 4 described above, and the heat of the electric heater 2 is increased by the heat insulating performance of the glass wool 3. We are considering making it difficult to escape outside the tube.

  FIG. 7 shows a third embodiment of the present invention. In this embodiment, the electric heater 2 along the outer periphery of the tube body 1 is covered with the silicon resin film 6 by dip molding or coating. The heater 2 is covered with the tube main body 1. More specifically, when the dip molding is adopted, the pipe main body 1 is immersed in the silicon resin paste together with the electric heater 2 and pulled up. When the coating 6 is formed on the outer peripheral portion of the tube main body 1 and application is adopted, the coating 6 is formed by applying a silicone resin paste on the electric heater 2 along the outer peripheral portion of the tube main body 1. Will be.

  Thus, in this way, the silicon resin film 6 is tightly formed on the tube main body 1 by dip molding or application, and the electric heater 2 is well fixed, and the first and second embodiments described above are used. Similarly to the case, it is possible to realize the countermeasure against freezing of the urea water supply pipe at a low cost.

  The material for forming the film 6 is not limited to silicon resin. However, since the silicon resin has relatively low heat conductivity, the glass wool 3 in the first and second embodiments described above. As in the case of, the effect of making it difficult for the heat of the electric heater 2 to escape outside the tube can be expected.

  FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, the electric heater 2 along the outer periphery of the tube main body 1 is moved by the heat shrinkable tube 7 (shrink tube) made of polystyrene. The electric heater 2 is covered with the pipe main body 1.

  That is, when the heat shrinkable tube 7 is formed in advance with a diameter larger than the outer diameter of the tube main body 1 and is put on the tube main body 1 along with the electric heater 2, the heat shrinkable tube 7 is contracted. The tube heater 1 is closely attached to the outer periphery of the tube body 1 and the electric heater 2 is well fixed to the outer periphery of the tube body 1. As in the case of the first to third embodiments described above, urea is used. Countermeasures for freezing water supply pipes can be realized at low cost.

  Here, FIG. 8 shows a state before heating the heat-shrinkable tube 7, but the state after the heat-shrinkable tube 7 is shrunk by heating is the coating film of FIG. 7 in the third embodiment. 6 is substantially the same as shown in FIG.

  The material of the heat-shrinkable tube 7 is not limited to polystyrene, but since polystyrene has a relatively low heat transfer property, the glass wool 3 and the third in the first and second embodiments described above are used. As in the case of the silicon resin in this embodiment, the effect of making it difficult for the heat of the electric heater 2 to escape to the outside of the tube can be expected.

  Note that the urea water supply pipe of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

It is a perspective view which partially cuts and shows the 1st example of a form of this invention. It is an enlarged view which shows the detail of the weave of the plain weave mesh of FIG. It is a perspective view explaining the covering operation | work to the pipe main body of a plain weave mesh. It is a perspective view which notches and shows the 2nd example of a form of this invention partially. It is an enlarged view which shows the detail of the stitch of the knit knitting mesh of FIG. It is a perspective view explaining the covering operation | work to the pipe | tube main body of a knit knitting mesh. It is a perspective view which partially cuts and shows the 3rd example of this invention. It is a perspective view which notches and shows the 4th form example of this invention partially. It is a perspective view which notches and shows a prior art example partially.

Explanation of symbols

1 Pipe body 2 Electric heater 3 Glass wool (fiber material)
4 Plain woven mesh 5 Knit knitted mesh 6 Coating 7 Heat shrinkable tube

Claims (5)

  A urea water supply pipe that guides urea water as a reducing agent to the selective catalytic reduction catalyst. The fiber material is arranged along the outer periphery of the pipe body along with an electric heater and crosses in a mutually opposite spiral. A urea water supply pipe, wherein the electric heater is covered with the pipe body by a plain weave mesh woven so as to form a cylindrical shape.   A urea water supply pipe that guides urea water as a reducing agent to the selective catalytic reduction catalyst. An electric heater is arranged along the outer periphery of the pipe body, and is knitted with a fiber material so as to form a chain-shaped endless stitch. A urea water supply pipe, wherein the electric heater is covered with the pipe body by a knit knitted mesh.   A urea water supply pipe for guiding urea water as a reducing agent to the selective catalytic reduction catalyst, wherein an electric heater is arranged along the outer periphery of the pipe body, and the electric heater is covered with the pipe body by a film formed by dip molding. A urea water supply pipe characterized by that.   A urea water supply pipe that guides urea water as a reducing agent to the selective catalytic reduction catalyst, the electric heater is arranged along the outer periphery of the pipe body, and the electric heater is covered with the pipe body by a coating formed by coating. A urea water supply pipe characterized by that.   A urea water supply pipe for guiding urea water as a reducing agent to the selective catalytic reduction catalyst, wherein an electric heater is disposed along the outer periphery of the pipe body, and the electric heater is covered with the pipe body by a heat shrinkable tube. A urea water supply pipe characterized by

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