WO2011068203A1

WO2011068203A1 - Reducing agent tank

Info

Publication number: WO2011068203A1
Application number: PCT/JP2010/071692
Authority: WO
Inventors: 朝幸伊藤; 泰雄岡本; 達夫益子
Original assignee: いすゞ自動車株式会社; 日野自動車株式会社
Priority date: 2009-12-04
Filing date: 2010-12-03
Publication date: 2011-06-09
Also published as: JP5681381B2; JP2011137441A

Abstract

Provided is a reducing agent tank which can reliably defrost a frozen reducing agent within the reducing agent tank, so that the cost is reduced. In a reducing agent tank (10), a suction pipe (12) for removing a liquid reducing agent from a tank body (11) is provided in the tank body (11) that stores the liquid reducing agent, and a medium pipe (14) through which a heat exchange medium circulates, is provided in the tank body (11) so as to be extended in one direction and folded in the opposite direction in the vicinity of a suction port (37) of the suction pipe (12), so that the temperature of the reducing agent in the vicinity of the suction port (37) is increased. On the portion of the medium pipe (14), which extends from the upstream side to the downstream side of a folded portion (31) of the medium pipe (14), a pair of partition wall plates (34, 35) are oppositely provided, and the suction port (37) is disposed within a space (36) between the pair of partition wall plates (34, 35).

Description

Reductant tank

The present invention relates to a reducing agent tank for storing a liquid reducing agent, and in particular, a medium pipe through which a heat exchange medium circulates is provided in the tank body to thaw the frozen reducing agent or prevent the reducing agent from freezing. It relates to a reducing agent tank.

The SCR system purifies NOx (nitrogen oxides) in exhaust gas using urea as a reducing agent precursor. The urea water is stored in the reducing agent tank and is appropriately supplied into the exhaust pipe. However, in extremely cold regions, the urea water in the reducing agent tank may freeze when the vehicle is stopped for a long time and the SCR system may not be operated. . Therefore, the urea water in the reducing agent tank is thawed by the engine cooling water, and a technique for circulating a cooling water pipe through which engine cooling water circulates at the bottom of the reducing agent tank has been developed in order to improve the thawing performance (Patent Document 2). reference). In addition, a box-shaped partition wall surrounding the cooling water pipe is provided, and heat is confined inside the partition wall to quickly thaw the frozen urea water near the suction port of the suction pipe and the sensor (water level sensor, concentration sensor). The technique which does is developed (refer patent document 1).

Japanese Patent No. 3687918 JP 2005-83223 A

However, in the above-described invention, a box-shaped partition is provided so as to surround the suction port of the suction pipe, the detection unit of the water level sensor, and the detection unit of the concentration sensor, and the heat capacity and thawing performance of these three parts are lowered. In addition, in order to operate the SCR system, it is important to first defrost the urea water around the suction pipe, and those who consider the priority for the above-mentioned invention that considers thawing of the above three parts at the same level However, the thawing performance is further enhanced.

In the above-described invention, there is no suggestion regarding detection of whether or not the urea water has been thawed, but it is necessary to detect whether or not the urea water has been thawed to determine whether or not the SCR system can be operated. In addition, the box type is expensive due to the side wall.

Accordingly, an object of the present invention is to provide a reducing agent tank that solves the above problems and can thaw the reducing agent frozen in the reducing agent tank with high performance or prevent freezing of the reducing agent with high performance and reduce costs. It is to provide.

In order to solve the above-mentioned problems, the present invention provides a tank body for storing a liquid reducing agent with a suction pipe for taking out the liquid reducing agent from the tank body, and a medium for heat exchange circulates in the tank body. In a reducing agent tank that is provided so as to extend in one direction and the medium pipe is folded back so as to be reversed in the vicinity of the suction port of the suction pipe, and the reducing agent is heated in the vicinity of the suction port, A pair of partition plates are provided facing the medium pipe extending from the upstream side of the folded portion of the medium pipe to the downstream side of the folded portion, and the suction port is disposed in the space between the pair of partition plates. .

It is good to arrange the detection part of the temperature sensor in the above space.

The outer edge of the partition plate may be bent along the medium pipe.

The tank body may have a detachable canopy, and the suction pipe and the medium pipe may be provided on the canopy.

The medium pipe in the tank body may be formed so as to extend downward from the canopy and bend so that the medium pipe facing the folded portion is horizontal.

The suction pipe in the tank body may be formed to extend downward from the canopy, and the lower end portion may be bent toward the folded portion side.

¡The partition plate may be fastened with bolts and nuts.

The suction pipe may be provided with a filter for preventing foreign matters from being sucked into the suction pipe and preventing the frozen urea water particles from being sucked into the suction pipe.

The tank body for storing the liquid reducing agent is provided with a suction pipe for taking out the liquid reducing agent from the tank body, and a medium pipe through which the medium for heat exchange circulates extends in one direction in the tank body. And a reductant tank in which the medium pipe is folded back so as to be reversed in the vicinity of the suction port of the suction pipe, and the frozen reducing agent is thawed in the vicinity of the suction port. A pair of partition plates are provided opposite to the medium pipe extending from the side to the downstream side of the folded portion, and the medium pipe between the partition plates is exposed, and the pair of partition plates and the medium pipe upstream of the folded portion And the suction port is disposed in a space surrounded by the folded portion and the medium pipe on the downstream side of the folded portion.

The suction port may be close to the medium pipe upstream from the folded portion.

According to the present invention, the reducing agent frozen in the reducing agent tank can be thawed with high performance, or the freezing of the reducing agent can be prevented with high performance, and the cost can be reduced.

FIG. 1 is a perspective view of a reducing agent tank. FIG. 2 is a side view of the main part of FIG. FIG. 3 is a plan view of FIG. FIG. 4 is a schematic diagram of an SCR system. FIG. 5 is a side view of a main part of a reducing agent tank showing another embodiment. 6 is a cross-sectional view taken along line AA in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 shows an SCR system 1 in which a reducing agent tank (urea tank) 10 according to this embodiment is used. The SCR system 1 is applied to an engine 2 mounted on a vehicle.

As shown in FIG. 4, a urea injection nozzle 4 that injects urea water, which is a liquid reducing agent, into the exhaust pipe 3 in order from the exhaust upstream side to an exhaust pipe 3 connected to an engine (for example, a diesel engine) 2. An SCR catalyst (selective reduction catalyst) 5 for reducing and purifying NOx (nitrogen oxide) in the exhaust gas with ammonia generated from urea water injected into the exhaust pipe 3 is disposed. The urea water is stored in the reducing agent tank 10. The reducing agent tank 10 is connected to the urea supply pump 7 via the first urea supply pipe 6, and the urea supply pump 7 is connected to the urea injection nozzle 4 via the second urea supply pipe 9. The urea supply pump 7 is controlled by an ECU (engine control unit or electronic control unit) 8. When the exhaust temperature at the inlet of the SCR catalyst 5 detected by an exhaust temperature sensor (not shown) reaches the activation temperature of the SCR catalyst 5, the ECU 8 supplies an amount of urea water corresponding to the amount of NOx in the exhaust gas. The urea injection nozzle 4 is supplied.

As shown in FIG. 1, the reducing agent tank 10 includes a tank main body 11 that stores urea water, a suction pipe 12 that penetrates the tank main body 11 from above and takes out urea water from the tank main body 11, A medium pipe 14 through which a heat exchange medium (in this embodiment, engine cooling water) for thawing frozen urea water in the tank body 11 circulates, and urea water in the tank body 11 provided in the tank body 11 A temperature sensor 13 for detecting the temperature of the water, a water level sensor (not shown) provided in the tank body 11 for detecting the level of urea water in the tank body 11, and urea water in the tank body 11 provided in the tank body 11. And a concentration sensor (not shown) for detecting the concentration of.

The tank body 11 is formed in a substantially rectangular parallelepiped shape, and has a detachable canopy 16 at the top.

The medium pipe 14 is made of a metal pipe excellent in heat transfer and corrosion resistance. The medium pipe 14 is provided through the canopy 16 so as to penetrate into the tank main body 11 from above and is folded back so as to be reversed at the bottom of the tank main body 11. It is provided to penetrate through. Further, the medium pipe 14 upstream of the folded portion 31 located at the lower end of the medium pipe 14 and the medium pipe 14 downstream of the folded portion 30 are bent so that the folded portion 31 side is horizontal. As shown in FIGS. 2 and 3, the folded portion 31 is formed by bending the medium pipe 14 so that the medium pipe 14 bends on a horizontal plane. An upstream straight portion 32 that extends linearly in the horizontal direction is formed in the medium pipe 14 on the upstream side of the folded portion 31, and the medium pipe 14 on the downstream side of the folded portion 31 is parallel to the upstream straight portion 32. An extending downstream straight portion 33 is formed, and the folded portion 31, the upstream straight portion 32, and the downstream straight portion 33 are U-shaped.

On the upper and lower sides of the medium pipe 14 extending from the upstream linear portion 32 to the downstream linear portion 33,

partition plates

34 and 35 made of stainless plates having excellent corrosion resistance are provided facing each other, and the medium pipe between the

partition plates

34 and 35 is provided. 14 is exposed, and heat from the medium is confined between the

partition plates

34 and 35. Specifically, the upper first partition plate 34 has a semicircular portion whose outer edge is formed in an arc shape along the outer periphery of the folded portion 31 and a linear shape whose outer edge is along the upstream linear portion 32 and the downstream linear portion 33. It is formed in the shape which connected the rectangular part formed in (2) by linear sides. The first partition plate 34 has an upper surface of the folded portion 31, an upper surface of the upstream linear portion 32, and a downstream side so as to block the upper side of the space 36 surrounded by the folded portion 31, the upstream linear portion 32, and the downstream linear portion 33. It is welded to the upper surface of the straight portion 33. The medium pipe 14 is vertically penetrated through the first partition plate 34. Further, the lower second partition plate 35 is formed such that the length of the rectangular portion extending in the extending direction of the

straight portions

32 and 33 is shorter than that of the first partition plate 34, thereby reducing the cost. The second partition plate 35 is welded to the lower surface of the folded portion 31, the lower surface of the upstream linear portion 32, and the lower surface of the downstream linear portion 33 so as to close the lower side of the space 36.

As shown in FIG. 1, the suction pipe 12 is provided through the canopy 16 so as to penetrate vertically. 2 and 3, the suction pipe 12 penetrates the first partition plate 34 downward, and the suction port 37 formed at the lower end is positioned in the space 36 between the

partition plates

34 and 35. ing. In particular, the suction port 37 is disposed closer to the upstream linear portion 32 having a higher temperature than the downstream linear portion 33 through which the medium after heat exchange flows, so that urea water can be efficiently taken in.

As shown in FIGS. 1 and 2, the temperature sensor 13 includes a base 20 attached on the canopy 16, and passes through the canopy 16 from the base 20 and hangs into the tank body 11 and penetrates the first partition plate 34. The extension part 21 is located at the lower end part in the space 36 between the

partition plates

34 and 35, and the detection part 22 is formed at the lower end part of the extension part 21 and detects the temperature. The detection unit 22 is close to the suction port 37 and is closer to the upstream linear portion 32 closer to the folded-back portion 31 than the suction port 37, and accurately measures the temperature in the vicinity of the suction port 37. .

The detection unit of the water level sensor and the detection unit of the concentration sensor (not shown) are respectively arranged at appropriate locations outside the space 36 between the

partition plates

34 and 35.

Next, the operation of this embodiment will be described.

As shown in FIGS. 4 and 2, when the temperature of the urea water in the tank body 11 detected by the temperature sensor 13 becomes lower than a predetermined value, the ECU 8 causes the urea water in the vicinity of the suction port 37 of the suction pipe 12 to flow. It is diagnosed that it is frozen, and the engine cooling water which is a medium for heat exchange is supplied to the medium pipe 14. The medium that has flowed into the medium pipe 14 flows while exchanging heat with the urea water in the tank body 11. In particular, since the upper and lower sides of the folded portion 31 are blocked by the

partition plates

34 and 35, the

partition plates

34 and 35 serve as an enclosure to prevent the heat of the medium pipe 14 from being dissipated. Moreover, since the detection part of a water level sensor and the detection part of a concentration sensor are arrange | positioned on the outer side between the

partition plates

34 and 35, the urea water of the suction inlet 37 vicinity has the heat capacity of the detection part of a water level sensor and the detection part of a concentration sensor. The urea water in the vicinity of the suction port 37 is preferentially thawed. For this reason, the thawing performance in the frozen urea water between the

partition plates

34 and 35 is improved, and the urea water is efficiently thawed.

When the temperature of the urea water in the tank body 11 detected by the temperature sensor 13 exceeds the predetermined value, the ECU 8 diagnoses that the urea water in the vicinity of the suction port 37 of the suction pipe 12 has been thawed, and the medium pipe 14 The SCR system 1 is operated by stopping the supply of the engine coolant to the urea and operating the urea supply pump 7. Since the urea water in the space 36 between the

partition plates

34 and 35 is sufficiently thawed, it is easily sucked up from the suction pipe 12 and passes through the first urea supply pipe 6, the urea supply pump 7 and the second urea supply pipe 9. It reaches the urea injection nozzle 4 and is injected from the urea injection nozzle 4 into the exhaust pipe 3.

In this way, the pair of

partition plates

34 and 35 are opposed to the medium pipe 14 that extends from the upstream linear portion 32 upstream of the folded portion 31 of the medium pipe 14 to the downstream straight portion 33 downstream of the folded portion 31. The medium pipe 14 between the

partition plates

34 and 35 is exposed, and the pair of

partition plates

34 and 35, the medium pipe 14 upstream of the folded portion 31, the folded portion 31, and the downstream portion of the folded portion 31 are provided. Since the suction port 37 is disposed in the space 36 surrounded by the medium pipe 14, the frozen urea water between the

partition plates

34 and 35 is thawed with a high thawing performance almost equivalent to that of a conventional reducing agent tank having a box-shaped partition. The waiting time until the SCR system 1 can operate can be shortened. The cost can be reduced by the absence of the side wall as compared with the conventional box-shaped partition wall.

Since the detection unit 22 of the temperature sensor 13 is disposed in the space 36 between the

partition plates

34 and 35, the temperature of the urea water in the vicinity of the suction port 37 can be detected accurately.

Since the suction port 37 is disposed close to the upstream linear portion 32 upstream of the folded portion 31, the urea water in the vicinity of the suction port 37 is quickly thawed, and the thawed urea water can be sucked efficiently.

Although the liquid reducing agent stored in the reducing agent tank 10 is made of urea water, it is not limited to this. Other liquid reducing agents that freeze in cold regions may also be used.

Further, although the first partition plate 34 is welded to the folded portion 31, it may be simply placed on the folded portion 31. Since the medium pipe 14 is vertically penetrated through the first partition plate 34, the first partition plate 34 does not fall off from the medium pipe 14.

The suction pipe 12 and the medium pipe 14 penetrate the canopy 16 up and down. However, the suction pipe 12 and the medium pipe 14 need only extend up and down in the tank body 11, and the suction pipe 12 and the medium pipe 14 outside the tank body 11 extend in the horizontal direction. It may be. In this case, the suction pipe 12 and the medium pipe 14 may be bent in the canopy 16.

In addition, although the folded portion 31, the upstream linear portion 32, and the downstream linear portion 33 are assumed to have a U shape, the present invention is not limited thereto. The folded portion 31 may be formed in a straight line and exhibit a U-shape, or the upstream linear portion 32 and the downstream linear portion 33 may be bent and exhibit a substantially O shape, The upstream linear portion 32 and the downstream linear portion 33 may be formed so as to approach each other as they are separated from the folded portion 31 and exhibit a horseshoe shape.

In addition, the medium pipe 14 is bent so that the folded portion 31, the upstream linear portion 32, and the downstream linear portion 33 are horizontal, but is not bent, and the upstream linear portion 32 and the downstream linear portion are not bent. The part 33 may extend vertically.

Further, when the temperature of the urea water in the tank body 11 detected by the temperature sensor 13 becomes lower than the temperature at which the urea water in the vicinity of the suction port 37 of the suction pipe 12 is considered to be frozen, the ECU 8 detects the medium pipe 14. However, the present invention is not limited to this. When the temperature of the urea water in the tank body 11 detected by the temperature sensor 13 reaches a predetermined temperature slightly higher than the temperature at which the urea water near the suction port 37 of the suction pipe 12 is frozen, the ECU 8 Cooling water may be supplied to raise the temperature of the reducing agent in the vicinity of the suction port 37. Freezing of the reducing agent can be prevented.

Next, another embodiment in which the

partition plates

34 and 35, the suction pipe 12 and the canopy 16 of the above-described embodiment are modified will be described.

As shown in FIGS. 5 and 6, the

partition plates

44 and 45 are bent at the

outer edge portions

40 and 41 along the medium pipe 14 so as to cover the side surface of the medium pipe 14 between the

partition plates

44 and 45. It has become. The

outer edge portions

40 and 41 of the

partition plates

44 and 45 are vertically spaced apart from each other, and the medium pipe 14 is partially exposed between the

partition plates

44 and 45. The

partition plates

44 and 45 are fastened by bolts 48 and nuts (not shown) extending vertically, and are fixed to the medium pipe 14.

The suction pipe 46 is bent at the lower end portion 54 toward the folded portion 31, is brought close to the folded portion 31, and faces the suction port 37 formed at the lower end portion 54 toward the folded portion 31. Further, the suction pipe 46 is provided with a filter 42 for preventing foreign matter from being sucked into the suction pipe 46 and preventing the frozen urea water particles from being sucked into the suction pipe 46. The filter 42 is provided at the lower end portion 54 of the suction pipe 46 so as to cover the suction port 37, and is formed to extend from the lower end portion 54 of the suction pipe 46 toward the folded portion 31.

The canopy 47 is formed in a disc shape. In the canopy 47, the medium pipe 14, the suction pipe 46, the temperature sensor 13 (see FIG. 1), the water level sensor 43 that detects the water level of urea water, and the outside air for introducing outside air according to the decrease of the urea water. An outside air introduction pipe 49 and a connector 50 for connecting a sensor in the tank body 11 (see FIG. 1) to the ECU 8 (see FIG. 4) are provided. The water level sensor 43 includes a guide rod 51 that extends downward from the canopy 47, a float 52 that is slidably provided on the guide rod 51, and a detector (not shown) that detects the vertical position of the float 52. A fixing member 53 that is fixed to the lower partition plate 45 is provided at the lower end of the guide rod 51.

Since the

outer edge portions

40 and 41 of the

partition plates

44 and 45 are bent along the medium pipe 14 in this way, the

partition plates

44 and 45 and the medium pipe 14 can be brought into contact with each other over a wide area. It is possible to prevent cold heat from entering the space 36 between the

partition plates

44 and 45 from the gap between the

media pipes

14 and 45.

In addition, since the

partition plates

44 and 45 are fastened by bolts 48 and nuts, the

partition plates

44 and 45 can be fixed to the medium pipe 14 with a simple structure and can be crimped and detachably fixed. Maintenance of the filter 42 and the like in 36 can be easily performed.

The medium pipe 14 in the tank body 11 is formed so as to extend downward from the canopy 47, and the medium pipe 14 facing the folded portion 31 is bent so as to be horizontal, so that the temperature rises in the space 36. It is possible to prevent the urea water that has been moved from moving upward.

The suction pipe 46 in the tank body 11 is formed so as to extend downward from the canopy 47 and the lower end portion 54 is bent toward the folded portion 31 side, so that urea water is taken in at a higher temperature position. Can do.

The

outer edge portions

40 and 41 of the

partition plates

44 and 45 may be in contact with each other, and the

partition plates

44 and 45 may cover all of the medium pipe 14 between the

partition plates

44 and 45.

DESCRIPTION OF SYMBOLS 10 Reductant tank 11 Tank main body 12 Suction pipe 13 Temperature sensor 14 Medium pipe 22 Detection part 31 Folding part 34 1st partition plate (partition plate)
35 Second partition plate (partition plate)
36 space 37 inlet

Claims

A tank body for storing the liquid reducing agent is provided with a suction pipe for taking out the liquid reducing agent from the tank body, and a medium pipe for circulating a heat exchange medium is provided in the tank body so as to extend in one direction. In the reducing agent tank in which the medium pipe is folded so as to be reversed in the vicinity of the suction port of the suction pipe, and the reducing agent is heated in the vicinity of the suction port, the above-mentioned from the upstream side from the folded portion of the medium pipe. A reductant tank, wherein a pair of partition plates are provided opposite to a medium pipe extending downstream from the folded portion, and the suction port is disposed in a space between the pair of partition plates.
The reductant tank according to claim 1, wherein a temperature sensor detector is disposed in the space.
The reducing agent tank according to claim 1, wherein an outer edge portion of the partition plate is bent along the medium pipe.
The reducing agent tank according to claim 1, wherein the tank body has a detachable canopy, and the suction pipe and the medium pipe are provided on the canopy.
5. The reducing agent tank according to claim 4, wherein the medium pipe in the tank body is formed so as to extend downward from the canopy, and the medium pipe facing the folded portion is bent so as to be horizontal.
6. The reducing agent tank according to claim 5, wherein the suction pipe in the tank body is formed so as to extend downward from the canopy, and a lower end portion thereof is bent toward the folded portion side.
The reductant tank according to claim 1, wherein the partition plate is fastened with a bolt and a nut.
The reducing agent tank according to claim 1, wherein the suction pipe is provided with a filter for preventing foreign matter from being sucked into the suction pipe and preventing the frozen urea water particles from being sucked into the suction pipe.
A tank body for storing the liquid reducing agent is provided with a suction pipe for taking out the liquid reducing agent from the tank body, and a medium pipe for circulating a heat exchange medium is provided in the tank body so as to extend in one direction. In the reducing agent tank in which the medium pipe is folded so as to be reversed in the vicinity of the suction port of the suction pipe and the frozen reducing agent is thawed in the vicinity of the suction port, from the upstream side from the folded portion of the medium pipe. A pair of partition plates are provided opposite to the medium pipe extending downstream from the folded portion and the medium pipe between the partition plates is exposed, the pair of partition plates, and a medium pipe upstream from the folded portion, A reducing agent tank, wherein the suction port is disposed in a space surrounded by the folded portion and a medium pipe downstream from the folded portion.
10. The reducing agent tank according to claim 9, wherein a detection unit of a temperature sensor is disposed in the space.
10. The reducing agent tank according to claim 9, wherein the suction port is located close to a medium pipe upstream from the folded portion.