JP2007010197A - Assembling method of heat exchanger for reducer container, and piping structure for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a piping structure capable of absorbing allowance of lowering in accuracy of dimension caused by bending work of a tube in a heat exchanger constituted by laying the bent tube in a reducer container. <P>SOLUTION: The tube is constituted in a state of being divided into a main body tube member 63 bent to be placed in the reducing agent container, and connecting tube members 61, 62 projecting outside of the reducer container, an end portion 63a of the main body tube member 63 is fixed to a canopy 20 of the reducer container, and end portions of the connecting tube members 61, 62 are fitted and inserted into the end portion of the fixed main body tube member 63, thus a dimension of the main body tube member 63 lower than the canopy 20 and dimensions of the connecting tube members 61, 62 higher than the canopy 20 are independently adjusted. The upper and lower piping dimensions with respect to the canopy 20 can be independently decided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust purification device that reduces and purifies nitrogen oxide (NOx) in exhaust using a liquid reducing agent, and in particular, suppresses freezing or freezing of a liquid reducing agent stored in a reducing agent container. The present invention relates to a heat exchanger used for thawing a liquid reducing agent.

  As a catalyst purification system for removing NOx contained in engine exhaust, an exhaust purification device as disclosed in Patent Document 1 has been proposed. The exhaust purification device injects and supplies a required amount of liquid reducing agent according to the engine operating state to the upstream side of the reduction catalyst disposed in the engine exhaust system via a reducing agent supply device controlled by a control unit. Thus, NOx in the exhaust gas and the liquid reducing agent are subjected to a catalytic reduction reaction to purify NOx into harmless components. Here, the reduction reaction mainly uses ammonia that has a good reaction with NOx, and the liquid reducing agent is mainly an aqueous urea solution that generates ammonia by hydrolysis with exhaust heat and water vapor in the exhaust. It is done. Such a liquid reducing agent such as an aqueous urea solution is stored in a dedicated reducing agent container.

The reducing agent container has an opening on the upper surface of the container body, and a canopy is detachably attached so as to close the opening. The canopy includes a water level meter that detects the remaining amount of the liquid reducing agent, a concentration meter that detects the concentration of the liquid reducing agent, a liquid reducing agent delivery pipe and a return pipe, a breather pipe that opens the upper space in the container to the atmosphere, and In addition, there are provided connecting pipes that serve as cooling water inlets and outlets of a heat exchanger that uses engine cooling water as a heat medium.
JP 2000-27627 A

  A heat exchanger using engine cooling water is used for the reducing agent container as described above, and this heat exchanger is formed by bending one pipe material so as to surround the delivery pipe, the water level meter, and the concentration meter. In addition to piping from the canopy, both ends of the canopy are taken out through the canopy as connecting pipes for cooling water inlet and outlet. The portion of the connecting pipe that protrudes out of the container is connected to a cooling water carrying pipe that has been extended from the engine cooling system when the vehicle is mounted.

  As described above, a heat exchanger for a reducing agent container is configured by piping a pipe material subjected to a plurality of bending processes in the reducing agent container. Generally, a pipe material has a dimensional accuracy every time bending is repeated. Since it gets worse, it is difficult to obtain the designed dimensions of a heat exchanger having multiple bent portions. That is, since the performance of the heat exchanger is proportional to the pipe length, it is desired to increase the total length as much as possible. However, in order to gain the length in the constrained space in the reducing agent container, the heat exchanger must be bent as much as possible. However, since the dimensional accuracy of the pipe material deteriorates as the bending process is repeated and deviations accumulate, the dimension does not go as designed as the bending process ends.

  If the dimensional accuracy is poor and the lower end of the heat exchanger does not reach the bottom of the container, problems such as affecting the measurement of the water level meter and the concentration meter may occur. For this reason, priority is given to the upper and lower dimensions in the container below the canopy, and the heat exchanger is piped, but this time, the dimensions of the connecting pipe portion that protrudes from the canopy to the outside of the upper container are out of order. This will cause problems such as in-vehicle dimensions of the reducing agent container.

  Focusing on such problems, the present invention proposes a method of assembling a heat exchanger capable of absorbing a reduction in dimensional accuracy due to bending of pipe material.

  According to the present invention, in order to solve the above-mentioned problem, a pipe material subjected to bending work one or more times from a canopy is placed in a reducing agent container in which a canopy for closing an opening formed on the upper surface is detachably attached. In a method of assembling a heat exchanger for a reducing agent container constituted by piping, an end of a main body pipe member that is bent and circulates in the reducing agent container is fitted into the canopy, and the main body pipe member below the canopy is The stage of temporarily fixing the main body pipe member to the canopy after determining the dimensions, and inserting the end of the connecting pipe member that protrudes out of the reducing agent container into the end of the temporarily fixed main body pipe member, A step of temporarily fixing the connecting pipe member to the main body pipe member after determining a dimension of the connecting pipe member above the main body, and a step of finally fixing the temporarily fixed main body pipe member and the connecting pipe member. It is characterized by.

  According to this method of assembling the heat exchanger, it is only necessary that the end portion of the main body pipe member to be bent can be fixed to the canopy, and there is no need to consider the protruding dimension on the canopy. The projecting dimensions outside the reducing agent container can be adjusted as appropriate by inserting a separate connecting pipe member into the main body pipe member, so that the dimension can be adjusted by absorbing the reduction in dimensional accuracy generated in the main body pipe member. Can be assembled on the street. That is, even if the main body pipe member has a reduced dimensional accuracy due to repeated bending, the main body pipe member may be piped considering only the vertical dimension in the reducing agent container below the canopy. If there is a canopy attachment error at the end, the outside of the container can be finished to the dimensions by adjusting and inserting the connecting pipe member accordingly. In other words, the piping dimensions below the canopy (that is, inside the container) and the piping dimensions above the canopy (that is, outside the container) can be determined separately, so that the top and bottom sides of the canopy can be assembled accurately according to the dimensions. It is possible to solve the problems of the prior art.

  In such an assembling method of the present invention, the main tube member and the connecting tube member may be temporarily fixed and finally fixed by nickel brazing. That is, nickel brazing is highly resistant to the mainstream urea aqueous solution as a liquid reducing agent, and the tube material can be made thinner than welding that melts the material. The thinner the tube, the higher the heat transfer efficiency, which contributes to improving the performance of the heat exchanger. Further, the material of the main body pipe member and the connecting pipe member is preferably made of stainless steel having high resistance to the urea aqueous solution.

  The piping structure of the reducing agent container heat exchanger proposed for the above assembly method according to the present invention is a main body in which the pipe material piped from the canopy to the reducing agent container is bent to circulate in the reducing agent container. The pipe member and the connecting pipe member that protrudes out of the reducing agent container are configured separately, and the end of the main pipe member is fixed to the canopy and the end of the main pipe member is fixed to the end of the main pipe member. The pipe structure is such that the dimensions of the main body pipe member below the canopy and the connection pipe member above the canopy can be individually adjusted.

According to the heat exchanger assembling method and the piping structure therefor according to the present invention, the pipe material is divided into the main body pipe member and the connecting pipe member, and the upper and lower outer pipe dimensions and the inner pipe dimensions across the canopy. Can be adjusted individually, and the reduction in dimensional accuracy due to bending of the main body tube member can be absorbed by adjusting the insertion of the connecting tube member and assembled with high dimensional accuracy.
Moreover, since the joint of the heat exchanger tube obtained by the present invention is only the joint of the connecting pipe member outside the container, the engine coolant is leaked from the joint into the container to change the concentration of the liquid reducing agent. There is almost no possibility of end.

The present invention is applicable to a reducing agent container 10 used in an exhaust gas purification apparatus as shown in FIG. 1, and such a reducing agent container 10 has a schematic structure as shown in FIG.
The illustrated exhaust purification device uses an aqueous urea solution as a liquid reducing agent, and purifies NOx contained in engine exhaust by a catalytic reduction reaction. An exhaust pipe Ep connected to the exhaust manifold Em of the engine E includes an oxidation catalyst S1 that oxidizes nitrogen monoxide (NO) to nitrogen dioxide (NO ₂ ) from the exhaust upstream side to the downstream side, and a liquid reducing agent. An injection nozzle N that supplies and supplies, a NOx reduction catalyst S2 that reduces and purifies NOx with ammonia obtained by hydrolyzing the liquid reducing agent, and an ammonia oxidation catalyst S3 that oxidizes ammonia that has passed through the NOx reduction catalyst S2 in this order. It is arranged. The liquid reducing agent injected and supplied from the injection nozzle N is hydrolyzed by exhaust heat and water vapor in the exhaust to generate ammonia. The generated ammonia reacts with NOx in the exhaust gas in the NOx reduction catalyst S2, and is purified into water and harmless gas. At this time, in order to improve the NOx purification rate by the NOx reduction catalyst S2, NO is oxidized to NO ₂ by the oxidation catalyst S1, it is improved to that ratio between NO and NO ₂ in the exhaust gas suitable for catalytic reduction reaction The Furthermore, since ammonia that has passed through the NOx reduction catalyst S2 is oxidized by the ammonia oxidation catalyst S3 disposed downstream of the exhaust gas, it is possible to prevent ammonia that emits a strange odor from being released into the atmosphere as it is.

  The liquid reducing agent stored in the reducing agent container 10 is provided to the reducing agent supply means NC (arrow X) through a delivery pipe having a suction port located at the bottom of the container (arrow X), and contributes to injection by the reducing agent supply means NC. The excess liquid reducing agent that has not been returned is returned into the reducing agent container 10 through the return pipe (arrow Y). The reducing agent supply means NC is controlled by a control unit ECU having a built-in computer, and supplies a necessary amount of liquid reducing agent according to the engine operating state to the injection nozzle N while mixing with air.

  As shown in FIG. 2, the reducing agent container 10 according to the present embodiment has a replenishing port 12 for replenishing a liquid reducing agent at the upper part of the side surface that forms two longitudinal widths of the container body 11 having a substantially rectangular parallelepiped shape. And a handle 13 to be gripped during conveyance. And the opening part is opened in the upper surface of the container main body 11, and the canopy 20 is attached with the some volt | bolt 21 so that attachment and detachment are possible.

  On the top surface of the canopy 20, a base 31 of a water level meter 30 that detects the remaining amount of the liquid reducing agent and a base 41 of a concentration meter 40 that detects the concentration of the liquid reducing agent are fastened together by bolts 22. . The water level meter 30 has its detection unit 32 suspended from its base 31, and the concentration meter 40 has its detection unit 42 suspended from its base 41 and is located at the bottom of the container body 11. Further, on the upper surface of the canopy 20, a liquid reducing agent delivery pipe 50 and a return pipe 51, connection pipes 61 and 62 serving as cooling water inlets and outlets of a heat exchanger 60 using engine cooling water as a heat medium, and a container A breather pipe 70 is opened to open the upper space inside. The connecting pipes 61 and 62 of the heat exchanger 60 are connected to a cooling water carrying pipe that has been extended from the engine cooling system when the vehicle is mounted.

  The heat exchanger 60 of the present embodiment includes a main body pipe member 63 that is bent from a plurality of places and bent from the canopy 20 so as to surround the water level meter 30 and the concentration meter 40 in the container main body 11. As shown in detail in the enlarged cross-sectional view of the main part of FIG. 3, the end portions of the connecting pipe members forming the connecting pipes 61 and 62 of the engine cooling water inlet and outlet are respectively inserted into both end parts 63a of the main body pipe member 63. It has a piping structure. A main body pipe member 63 constituting the heat exchanger 60 in the container main body 11 extends from the canopy 20 to the bottom so as to surround the water level meter 30 and the liquid reducing agent delivery pipe 50, and surrounds the concentration meter 40 from the bottom. The intermediate bent portion 64 extending to the upper end portion is supported by a metal bracket 23 fixed to the lower surface of the canopy 20. In this way, according to the heat exchanger 60 formed by bending a plurality of pipes, the length of the main body pipe member 63 through which the engine cooling water passes can be earned, so that it is efficient with the liquid reducing agent. Heat exchange can be performed.

  Further, as shown in FIG. 2, at the lowermost part of the main body pipe member 63, a schematic box having only an upper surface opened so as to protect the water level meter 30 and the concentration meter 40 from the ice pieces when the liquid reducing agent freezes. A shape protector 80 is fixed. By doing in this way, even if the ice piece of a liquid reducing agent may be violated in the container main body 11, the water level meter 30 and the concentration meter 40 are protected and the occurrence of a failure can be prevented.

  As shown in FIG. 3, the end 63a of the main body pipe member 63 has an enlarged inner diameter so that the ends of the connecting pipe members 61 and 62 can be received in the end 63a having a predetermined length. The end 63a thus fitted is fitted into the fixing hole of the canopy 20 and fixed. By inserting the connecting pipe members 61 and 62 into the end 63a fixed to the canopy 20, the connecting pipe members 61 and 62 from the canopy 20 are separated from the dimensions of the main pipe member 63 below the canopy 20. The protruding dimension can be adjusted. In addition, the example which produces the whole main body pipe member 63 as the same diameter as the edge part 63a is also possible, Furthermore, the fitting insertion structure of the main body pipe member 63 and the connection pipe members 61 and 62 is reverse to illustration, That is, an insertion structure in which the end diameters of the connecting pipe members 61 and 62 are widened and the end portions of the main body pipe member 63 are inserted into the connecting pipe members 61 and 62 can be considered. However, considering that the end of the main body pipe member 63 is fixed to the canopy 20, a structure in which the end diameter of the main body pipe member 63 is widened to receive the ends of the connecting pipe members 61 and 62 is more suitable.

  In addition, as shown in FIG. 4, a structure is also conceivable in which the end member 65 is fixed to the outer peripheral surface as an end portion of the main body pipe member 63 and the end portions of the connecting pipe members 61 and 62 are received therein. In this case, the end member 65 may first be fixed to the canopy 20 and the main body pipe member 63 may be assembled, or the end member 65 may be fixed to the main body pipe member 63 before the canopy. You may make it the assembly method fixed to 20. However, in the case of the structure shown in FIG. 4, the number of joints between the pipes increases, and the joint between the main body pipe member 63 and the end member 65 is located in the container main body 11, and the container from the joints. There is a possibility of engine coolant leaking into the interior. As a structure for solving this, the structure of FIG. 3 has been devised.

  In the case of the present embodiment, the main body pipe member 63 and the canopy 20, and the main body pipe member 63 and the connecting pipe members 61 and 62 are joined by nickel brazing. Nickel brazing is highly resistant when using an aqueous urea solution as a liquid reducing agent as in this example, and the tube material can be made thinner compared to welding that melts the material. And the performance of the heat exchanger can be improved. The material of the main body pipe member 63 and the connecting pipe members 61 and 62 is stainless steel, particularly SUS304 in this example, which also has high resistance to an aqueous urea solution.

A method for assembling the heat exchanger 60 having the above piping structure will be described with reference to FIGS.
First, as shown in FIG. 5, a required portion is bent to form the main body pipe member 63, and both end portions 63 a thereof are fitted into the fixing holes of the canopy 20. Then, as shown in FIG. 6, the canopy 20 fitted with the main body pipe member 63 is placed on the mounting plate 101 in the assembly jig 100, and the three edge portions of the canopy 20 are clamped by the clamps 102, 103, 104 and positioned. To do. The mounting plate 101 is supported by four columns 105, 106, 107, and 108, and the height (separation distance) from the lower plate 109 is the vertical dimension of the main body pipe member 63 in the reducing agent container 10. It is determined to match. Therefore, by placing the canopy 20 on the mounting plate 101 and positioning with the clamps 102 to 104, the vertical dimension of the main body tube member 63, that is, the in-container dimension of the heat exchanger 60 below the canopy 20 is set. The distance between the lower plate 109 and the lower plate 109 is regulated according to design dimensions. In this state, as shown in the enlarged view of FIG. 6B, the end 63a and the canopy 20 are temporarily fixed by temporary fixing means 63b such as partial welding or nickel brazing. In this example, the protector 80 is attached at this time (the attachment time of the protector 80 is not limited to this).

  Next, as shown in FIG. 7, the end portions of the connecting tube members 61 and 62 are fitted into the end portions 63 a of the main body tube member 63 temporarily fixed to the canopy 20. Then, as shown in FIG. 8, the direction and the protruding dimension of the connecting pipe member 61 (62) are positioned by the positioning pin 110 that is slidably supported on the column 105. Although FIG. 8 shows only the example of the connecting pipe member 61, the same applies to the connecting pipe member 62. The positioning pin 110 has a height (separation distance) from the mounting plate 101 determined by the support means 111 fixed to the support column 105, and this is determined from the projecting dimension of the connecting pipe member 61 (62), that is, from the canopy 20. It matches the outer container dimensions of the upper heat exchanger 60. Therefore, the position (rotation direction and height) of the connecting pipe member 61 (62) inserted into the end 63a of the main body pipe member 63 is aligned with the retracted positioning pin 110, and the positioning pin 110 is moved. When extruded and inserted into the opening of the connecting pipe member 61 (62), the projecting dimension and direction of the connecting pipe member 61 (62) are regulated according to the design dimensions. In this state, as shown in the enlarged view of FIG. 8B, the end 63a of the main body pipe member 63 and the connecting pipe member 61 (62) are temporarily fixed by temporary fixing means 61a such as partial welding or nickel brazing. .

  After the temporary fastening of both the connecting pipe members 61 and 62 is finished, the canopy 20 is removed from the assembly jig 100, and after the temporary fastening, nickel brazing is performed and joined. By joining the joint with nickel brazing, the resistance to the liquid reducing agent is increased, and the joint between the main body pipe member 63 and the connecting pipe members 61 and 62 is provided at one position for each end located outside the reducing agent container 10. Therefore, it is difficult to cause poor bonding, and the possibility of changing the concentration of the liquid reducing agent by leaking engine cooling water from the seam into the container is very low.

Schematic of the exhaust gas purification apparatus using a reducing agent container. The structure figure which showed the outline of the reducing agent container. The principal part sectional view showing an example of the piping structure of the heat exchanger concerning the present invention. The principal part sectional drawing which showed the other example of FIG. Process drawing explaining the assembly method of the heat exchanger which concerns on this invention. The process following FIG. 5 is shown, (A) is the process figure seen from the assembly jig | tool, and (B) from the side of the assembly jig. Process drawing seen in the principal part cross section which shows the process following FIG. The process following FIG. 7 is shown, (A) is the process figure which looked at the principal part pointed by arrow A in (A) from the side from the top of the assembly jig.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reducing agent container 20 Canopy 60 Heat exchanger 61,62 Connection pipe member 63 Main body pipe member 100 Assembly jig

Claims (6)

Heat for a reducing agent container configured by piping a pipe material that has been bent once or more in a reducing agent container that is detachably attached to a canopy that closes an opening formed on the upper surface. In the assembly method of the exchanger,
The end of the main body tube member that is bent and circulates in the reducing agent container is fitted into the canopy to determine the size of the main body tube member below the canopy, and then the main body tube member is temporarily fixed to the canopy And the stage of
An end of the connecting pipe member that protrudes outside the reducing agent container is fitted into the end of the temporarily fixed main body pipe member, and after determining the dimensions of the connecting pipe member above the canopy, the connecting pipe Temporarily fixing the member to the main body tube member;
A method of assembling the heat exchanger, comprising: temporarily fixing the temporarily fixed main body pipe member and the connecting pipe member.   2. The heat exchanger assembling method according to claim 1, wherein an end portion of the connecting pipe member is received in an end portion of the temporarily fixed main body pipe member.   The heat exchanger assembling method according to claim 1 or 2, wherein the main tube member and the connecting tube member are temporarily fixed and permanently fixed by nickel brazing.   The heat exchanger assembly method according to claim 1, wherein a material of the main body pipe member and the connection pipe member is stainless steel. It is the piping structure of the heat exchanger for reducing agent containers for the assembly method of the heat exchanger of any one of Claims 1-3,
The pipe material piped from the canopy into the reducing agent container is divided into a main body pipe member that bends and circulates in the reducing agent container, and a connecting pipe member that protrudes outside the reducing agent container. The end of the main body tube member is fixed to the canopy, and the end of the connecting tube member is fitted into the end of the fixed main body tube member, and the main body tube below the canopy A piping structure of a heat exchanger for a reducing agent container, wherein the dimension of the member and the dimension of the connecting pipe member above the canopy can be individually adjusted.   6. The piping structure of a heat exchanger for a reducing agent container according to claim 5, wherein an inner diameter of the end portion of the main body pipe member is a diameter capable of receiving an end portion of the connecting pipe member.

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