JP2010071263A - Urea water tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of a urea water tank while providing conventional thawing performance by simplifying the urea water thawing device of the urea water tank. <P>SOLUTION: This urea water tank having a urea water thawing device comprises: a cooling water pipe 6 which is fixed to a top cover 2 for closing an opening in the upper surface of a box-shaped tank body 1, allows an inlet 6a and an outlet 6e formed in the top cover 2 to communicate with each other through a U-shaped folded part 6c in the tank body 1, and allows engine cooling water for heating urea water to flow into a pipe; and a thawing box 5 which is positioned at the bottom of the tank body 1, made of plates, formed in a generally box shape having a slit allowing the urea water to pass therethrough, and surrounds the suction port 7a of a suction pipe 7 for feeding the urea water to a urea SCR system and the ends of sensors. The cooling water pipe 6 extends downward from the inlet 6a and the outlet 6e, bends and horizontally extends near the bottom of the tank body 1, and reaches at the folded part 6c formed in the thawing box 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a urea water tank mounted on a vehicle for use in a urea SCR (selective reduction catalyst) system for detoxifying NOx (nitrogen oxide) in exhaust gas, and in particular, urea water in a urea water tank. It relates to a thawing device.

  The urea SCR system, which is one of exhaust gas purification technologies, detoxifies NOx by catalytic reduction reaction of NOx in exhaust gas and urea water as a reducing agent. A urea water tank that stores the urea water is a Like a fuel tank, it is mounted on a vehicle and used.

  Vehicles equipped with the urea SCR system are often used in cold regions, and when the vehicle is stopped for a long time, the urea water stored in the urea water tank freezes in a sub-freezing environment. End up. For this reason, when the engine is started again, urea water cannot be temporarily supplied to the urea SCR system.

  From when the vehicle engine is started until the frozen urea water is thawed and supplied to the urea SCR system, the exhaust gas cannot be reduced, and harmful NOx is discharged. Therefore, it is necessary to thaw frozen urea water as soon as possible and supply it to the urea SCR system.

  In Patent Document 1, by providing a vertical partition member with unevenness that divides the inside of the tank into a region including sensors and pipes and other regions, the movement of ice blocks frozen by urea water is suppressed, The partition member is provided with holes at predetermined intervals, a bowl-like part is provided outside the upper edge of the hole, and an inclined part is provided obliquely upward on the inner side of the lower edge. A urea water tank that can be efficiently dissolved in the inner region of the partition member is described.

In order to thaw frozen urea water, a urea water thawing device including a cooling water pipe and a thawing box has been provided in the urea water tank (Patent Documents 2 and 3).
In the conventional urea water thawing device, as shown in FIGS. 6 and 7, in order to thaw the frozen urea water, the engine cooling water heated by the radiator is circulated through the cooling water pipe 6 arranged in the tank body 1. It was.

  In such a urea water tank, pipes and sensors protruding inside the tank body 1 are attached to a canopy 2 fixed with bolts to an opening provided in a part of the upper surface of the tank body 1. The cooling water pipe 6 is attached through the canopy 2 from the inlet 6a and the outlet 6e, and is formed in a shape in which a pipe having a U-shaped folded portion 6c is bent at a plurality of locations (FIG. 7). . A suction pipe 7 for sending urea water to the urea SCR system is attached through the canopy 2, and a suction port 7 a at the tip is opened near the center of the bottom of the tank body 1. A return pipe 9 for returning urea water from the urea SCR system to the urea water tank and a breather pipe 13 for venting air also extend through the canopy 2 (FIG. 7). The concentration sensor 3 and the liquid level sensor 4 are suspended from the canopy 2 near the bottom near the center of the tank body 1 (FIG. 6).

  The conventional cooling water pipe 6 has a forward path portion 6b and a return path portion 6d extending downward from an inlet 6a and an outlet 6e penetrating the canopy 2 on the rear side of the tank body 1, and bent forward near the bottom of the tank body 1. It extends to the (water injection port 1a side) and bends upward on the front side of the tank body 1 to form a U-shaped folded portion 6c near the canopy 2 (FIG. 7). Since the cooling water pipe 6 extends over a wide area in the tank body 1 in this way, the internal urea water can be thawed uniformly.

  As described above, the cooling water pipe 6 is disposed so as to surround the sensors located near the center of the tank body 1 (FIG. 6). Moreover, the folding | returning part 6c is supported via the flat fixed plate 12 fixed to the canopy 2, and it can endure the vibration of a vehicle. Similarly, the suction pipe 7 for supplying urea water to the urea SCR system and the forward path portion 6 b are fixed by heater plates 8, 8, 8.

  A substantially box-shaped thawing box 5 having through holes for sensors and pipes is installed at the bottom of the tank body 1 and surrounds the suction port 7a of the suction pipe 7 and the tips of the sensors. Thereby, the urea water in the thawing box 5 is thawed earliest and supplied from the suction pipe 7 to the urea SCR system.

JP 2005-299510 A JP 2005-351253 A JP 2006-226282 A

In such a urea water thawing device, it is necessary to defrost a large amount of urea water in as short a time as possible, so the arrangement of the cooling water pipes in the tank body is complicated, and the entire device has become large. .
However, in recent years, with the reduction in weight and price of vehicles, urea water tanks have been required to be reduced in size and cost. Therefore, simplification of the structure of the tank body, simplification of sensors, simplification of piping, and the like have been considered, and simplification has also been desired in the urea water thawing device.
Furthermore, since it has become necessary to reduce material costs due to soaring material prices, cost reduction has become an issue, particularly for pipe materials that are more expensive than plate materials.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to simplify the urea water thawing device of the urea water tank, and to reduce the cost while providing the same thawing performance as the conventional one.

In the present invention, means for solving the above problems are as follows.
1st invention is fixed to the canopy which obstruct | occludes opening of the upper surface of the tank main body formed in the box shape, and between the inlet_port | entrance and exit formed in a canopy, a U-shaped folding | returning part is set inside the tank main body. It is formed in a substantially box shape with a cooling water pipe that allows the engine cooling water for heating urea water to flow through the inside of the pipe and a slit that is made of a plate material and that allows passage of urea water. A urea water tank having a urea water thawing device comprising a suction port of a suction pipe for sending urea water to a urea SCR system and a thawing box surrounding a tip of sensors, wherein the cooling water pipe is connected from an inlet and an outlet. It hangs downward, bends near the bottom of the tank body, extends horizontally, and reaches the folded portion provided in the thawing box.

  According to a second invention, in the first invention, outside the thawing box, between the forward path portion from the inlet of the cooling water pipe to the folded portion and the return path portion from the folded portion to the outlet. One flat heater plate is bridged and joined.

According to a third invention, in the first invention, outside the thawing box, between the forward path portion from the inlet of the cooling water pipe to the folded portion and the return path portion from the folded portion to the outlet. The pair of flat plate heater plates are bridged to sandwich the forward path part and the return path part, and the heater plate is joined to the forward path part and the return path part.
A fourth invention is characterized in that, in the third invention, one of the pair of heater plates extends upward and is joined to the canopy.

  According to the first invention, the cooling water pipe is suspended downward from the inlet and outlet, bent near the bottom of the tank body, extends horizontally, and reaches the folded portion provided in the thawing box. The total length of the cooling water pipe can be shortened to reduce the material cost, and the man-hours for bending the cooling water pipe can be reduced, and the manufacturing cost of the urea water tank can be reduced.

  According to the second invention, outside the thawing box, there is one sheet between the forward path portion from the inlet to the folded portion of the cooling water pipe and the return path portion from the folded portion to the outlet. By linking and joining flat heater plates, the heat radiation area where heat exchange between cooling water and urea water can be expanded, and the cooling water pipe can be shortened with the same thawing performance as before. It is possible to reduce the manufacturing cost of the urea water tank by reducing the material cost and man-hours.

  According to the third invention, outside the thawing box, a pair of flat plates is provided between the forward path portion from the inlet of the cooling water pipe to the folded portion and the return path portion from the folded portion to the outlet. A heater plate is sandwiched between the forward path and the return path, and the heater plate is joined to the forward path and the return path to expand the heat radiation area where heat is exchanged between the cooling water and the urea water. Therefore, the cooling water pipe can be shortened with the same thawing performance as before, and the manufacturing cost of the urea water tank can be reduced by suppressing the material cost and man-hour. In addition, since the urea water is intensively heated in a cavity surrounded by the two heater plates and the forward path part and the return path part of the cooling water pipe, the thermal efficiency is improved and the thawing performance is improved. As a result, the length of the cooling water pipe can be reduced by about 40% with the same thawing performance as before, and the material cost can be reduced.

  According to the fourth invention, since one of the pair of heater plates is extended upward and joined to the canopy, the rigidity of the cooling pipe is increased and the vibration resistance is improved. It is possible to prevent cracks from occurring in pipes and the like. Moreover, since the heat radiation area of the heater plate is increased, the thawing performance can be improved.

Hereinafter, a urea water tank according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a part of a urea water tank according to the first embodiment of the present invention.

  The urea water tank is formed with a water injection port 1a for pouring urea water from the outside into the front portion of a SUS (stainless steel) tank body 1 formed in a substantially rectangular parallelepiped box shape, and is closed with a cap. Further, a liquid level check gauge 1b for checking the amount of liquid in the urea water tank is formed on the side surface portion. The upper surface of the tank body 1 is notched from the rear side to the center, and an opening is provided. The opening is closed by a canopy 2 having a number of through holes for mounting pipes and sensors, and the periphery is bolted. It is fixed. Further, a drain hole for discharging urea water is provided at the bottom and is closed by a drain plug 1c.

Near the center of the urea water tank, the columnar concentration sensor 3 and the liquid level sensor 4 are suspended from the canopy 2 side by side and extend to the vicinity of the bottom. Respective detection units are provided at the tip of the concentration sensor 3 and the liquid level sensor 4.
Sensor mounting sheets 2a and 2a having holes are respectively provided on the upper surfaces of the mounting holes of the sensors of the canopy 2 (FIG. 2), and the sensors are fixed to the respective sensor mounting sheets 2a and 2a with bolts. And indirectly fixed to the canopy 2 (FIG. 1).

The urea water tank includes a urea water thawing device including a thawing box 5 and a cooling water pipe 6. FIG. 2 is a perspective view showing the urea water thawing device.
The thawing box 5 is formed by arranging two SUS plates bent in an L shape so as to face each other into a square tube shape, and a body member 5a having a slight gap between the end portions of the SUS plate is attached to the tank body 1. It is arranged at the center of the bottom and is vertically closed by a rectangular SUS top plate member 5b and a bottom plate member (not shown) serving as an end plate of the body member 5a. The top plate member 5b is formed with two round holes for inserting each sensor, and two adjacent corners of the four corners are cut out in an arc shape.
In this way, the thawing box 5 is formed in a box shape that surrounds the tip portions of the concentration sensor 3 and the liquid level sensor 4, the folded-back portion 6c of the cooling water pipe 6 described later, and the suction port 7a of the suction pipe 7 (FIG. 1). ).

  As for the cooling water pipe 6, the forward path part 6b from the inlet 6a to the folding | returning part 6c and the return path part 6d from the folding | turning part 6c to the outlet 6e are arrange | positioned in parallel at right and left. The forward path part 6b and the return path part 6d extend downward from the inlet 6a and the outlet 6e arranged side by side through the rear part of the canopy 2, respectively, while increasing the distance from each other while inclining forward in the middle, and again directly below Parallel to the direction. It is introduced into the thawing box 5 through a notch at the corner of the top plate member 5b of the thawing box 5 and reaches the bottom of the tank body 1 to bend forward with a distance of 20 to 30 mm from the bottom plate member of the thawing box 5. In parallel with the horizontal direction, the U-shaped folded portions 6c communicate with each other.

  The folded portion 6c is located on the front side of the concentration sensor 3 and the liquid level sensor 4, and the cooling water pipe 6 surrounds the front ends of the sensors from the front and the left and right (FIG. 1). The tip of the U-shaped folded portion 6 c is formed in a straight line and is brazed to the inner wall of the thawing box 5.

The suction pipe 7 for sending urea water from the urea water tank to the urea SCR system extends through the rearmost part of the canopy 2 and extends downward adjacent to the forward path part 6b of the cooling water pipe 6 so that heat exchange is performed, It is bent forward in the thawing box 5. Then, a suction port 7a is provided that extends to the center of the urea water tank, that is, between the concentration sensor 3 and the liquid level sensor 4 and has the tip opened toward the bottom. Since the suction pipe 7 and the cooling water pipe 6 are separated above the inclined part of the cooling water pipe 6, the suction pipe 7 and the forward path part 6b can be obtained by brazing the three heater plates 8, 8, 8 between them. And the rigidity is increased, and the urea water in the suction pipe 7 is prevented from freezing by heat exchange. In the heater plate 8 having the highest position, a part covering the forward path portion 6b of the cooling water pipe 6 is notched and the forward path portion 6b is exposed.
A return pipe 9 for returning urea water from the urea SCR system to the urea water tank and a breather pipe 13 for venting air pass through the canopy 2 and open inside the tank body 1.

As shown in FIG. 2 and FIG. 3, a pair of SUS made from the front and rear is provided between the forward path portion 6 b and the return path portion 6 d of the cooling water pipe 6 from slightly below the inclined portion to the thawing box 5. The heater plates 10 and 11 are bridged, and the forward path portion 6b and the return path portion 6d are sandwiched between the heater plates 10 and 11. The width of the heater plates 10 and 11 is substantially equal to the distance between the forward path part 6b and the return path part 6d, and the side ends are joined to the forward path part 6b and the return path part 6d by brazing.
In addition, a suction pipe 7 that is parallel to the forward path portion 6b is joined to the back surface of the joint portion of the front heater plate 10 with the cooling water pipe 6 (FIG. 2).

  In the urea water tank configured as described above, when the engine is started with the urea water frozen, the engine cooling water heated by the radiator flows through the cooling water pipe 6 and gradually thaws the surrounding urea water. To go. In particular, in the thawing box 5, urea water is preferentially heated and defrosted, and sent from the suction pipe 7 to the urea SCR system.

  At this time, the cooling water pipe 6 hangs downward in parallel from the inlet 6a and the outlet 6e, bends in the vicinity of the bottom of the tank body 1 and extends horizontally, and reaches the folded portion 6c provided in the thawing box 5. As a result, the total length of the cooling water pipe 6 can be shortened and the material cost can be reduced, and the man-hours for bending the cooling water pipe 6 can be reduced, and the manufacturing cost of the urea water tank can be reduced. .

Further, a pair of flat plate-like heater plates 10 and 11 are bridged between the forward path portion 6b and the return path portion 6d of the cooling water pipe 6, and the forward path portion 6b and the return path portion 6d are sandwiched between the heater plates 10 and 11. By joining the forward path portion 6b and the return path portion 6d, the heat radiation area where heat exchange between the cooling water and the urea water is performed can be expanded, and the cooling water pipe 6 can be shortened with the same thawing performance as before. It is possible to reduce the manufacturing cost of the urea water tank by reducing the material cost and man-hours. Further, since the urea water is intensively heated in the cavity surrounded by the two heater plates 10 and 11 and the forward path portion 6b and the return path portion 6d of the cooling water pipe 6, the thermal efficiency is improved and the thawing performance is improved. To do. As a result, the length of the cooling water pipe 6 can be reduced by about 40% with the same thawing performance as before, and the material cost can be reduced.
In addition, as long as sufficient thawing | decompression performance can be obtained, the heater plate bridged between the outward path part 6b and the return path part 6d may be one.

<Second Embodiment>
When used in a vehicle with strong vibrations, or when the vibration increases as the total height of the urea water tank and the cooling water pipe 6 become longer, the upper portion of the heater plate 10 is placed up to the canopy 2 as shown in FIGS. You may extend and braze.

  In this case, the upper part of the heater plate 10 on the front side, which is a distance from the inlet 6a and the outlet 6e, is extended to the canopy 2, and the tip is bent to provide a joining margin 10a (FIG. 5). By joining the joining margin 10a and the inner wall of the canopy 2 by brazing, the cooling water pipe 6 is strongly fixed to the canopy 2 at three points of the inlet 6a, the outlet 6e, and the joining allowance 10a, so that the rigidity against vibration is increased. And the crack of the cooling water pipe 6 due to vibration from the vehicle can be prevented. Moreover, since the heat dissipation area of the heater plate 10 is increased, the thawing performance can be improved.

It is a perspective view which cuts and shows one side of a urea water tank concerning a 1st embodiment of the present invention. It is a perspective view which shows the urea water thawing | decompression apparatus of the urea water tank. It is an enlarged view which shows the joining state of the cooling water pipe and heater plate in the A section of FIG. It is a perspective view which shows the urea water thawing | decompression apparatus which concerns on 2nd Embodiment of this invention. It is a side view of the urea water thawing device. It is a perspective view which cuts and shows one side of the conventional urea water tank. It is a perspective view which shows the urea water thawing | decompression apparatus of the conventional urea water tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tank main body 1a Water inlet 1b Liquid level check gauge 1c Drain plug 2 Canopy 2a Sensor mounting sheet 3 Concentration sensor 4 Liquid level sensor 5 Thaw box 5a Body member 5b Top plate member 6 Cooling water pipe 6a Inlet 6b Outward path part 6c Turn-back part 6d Return path 6e Outlet 7 Suction pipe 7a Suction port 8 Heater plate 9 Return pipe 10 Heater plate (front side)
10a Joining allowance 11 Heater plate (back side)
12 fixed plate 13 breather pipe

Claims (4)

It is fixed to a canopy that closes the opening on the top surface of the tank body formed in a box shape, and the inlet and outlet formed in the canopy communicate with each other through a U-shaped folded portion inside the tank body, and a pipe A cooling water pipe for circulating engine cooling water for heating urea water inside;
A thawing box that is located at the bottom of the tank body, is made of a plate material and has a substantially box shape with a slit through which urea water can pass, and surrounds the suction port of the suction pipe that sends urea water to the urea SCR system and the tips of sensors. A urea water tank equipped with a urea water thawing device comprising:
A urea water tank, wherein the cooling water pipe is suspended downward from an inlet and an outlet, bent near the bottom of the tank body, extends horizontally, and reaches the folded portion provided in the thawing box.   Outside the thawing box, a flat plate-like heater plate is bridged between the forward path portion from the inlet to the folded portion of the cooling water pipe and the return path portion from the folded portion to the outlet. The urea water tank according to claim 1, wherein the urea water tank is joined.   Outside the thawing box, a pair of flat heater plates are bridged between the forward path portion from the inlet to the folded portion of the cooling water pipe and the return path portion from the folded portion to the outlet. The urea water tank according to claim 1, wherein the forward path part and the backward path part are sandwiched, and the heater plate is joined to the forward path part and the backward path part.   The urea water tank according to claim 3, wherein one of the pair of heater plates extends upward and is joined to the canopy.

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