JP2003343250A - Heat exchanger with catalyst for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger with a catalyst for an internal combustion engine reduced in space by an integral formation of a catalyst and a heat exchanger and having high cooling ability. <P>SOLUTION: In a heat exchanger disposed in the exhaust gas passage of the internal combustion engine, the heat exchanger consisting of a cylindrical exhaust gas passage layer and a cooling fluid passage layer is disposed at the surroundings of the catalyst having an oxidation function. The catalyst and the exhaust gas passage layer are interconnected such that after exhaust gas passes through the catalyst, it flows in the exhaust gas passage layer of the heat exchanger. A first fin to axially guide exhaust gas is disposed in the exhaust gas passage layer. A second fin to peripherally guide cooling fluid is disposed in the cooling fluid passage layer, and the second fin is parted in a plurality of spots on a periphery. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas cooling heat exchanger installed in an exhaust passage of an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 7 is a schematic system diagram of a conventional internal combustion engine 300 having a catalyst 91 and a heat exchanger 92 in an exhaust passage 90. In the internal combustion engine 300, a mixture of air and fuel gas is supplied to the internal combustion engine main body 95 through the air supply pipe 96, the mixture is burned in a combustion chamber (not shown), and exhaust gas is exhausted through the exhaust passage 90. It is discharged to the outside. A catalyst 91, a heat exchanger 92, and a silencer 93 are installed in this order from the upstream side in the exhaust pipe 94 connected to the internal combustion engine body 95.

Since the exhaust gas oxidation reaction carried out by the catalyst 91 is not carried out below a predetermined temperature, the catalyst 91 is generally arranged upstream of the heat exchanger 92 as shown in FIG. is there. By the way, this catalyst 91 and heat exchanger 9
When 2 and 2 are separately arranged on the exhaust passage 90 as shown in FIG. 7, a large installation space is required. Therefore, if both are integrated, the condensed water is likely to be accumulated in the heat exchanger 92, and the condensed water absorbs the impurities to absorb the impurities.
Because the exhaust gas passage inside may become clogged,
In the past, it has been difficult to consolidate the two into one to save space.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a heat exchanger with a catalyst for an internal combustion engine, which has a space saving by integrating a catalyst and a heat exchanger and has a high cooling property. .

[0005]

In order to solve the above problems, according to the invention of claim 1, in a heat exchanger installed in an exhaust passage of an internal combustion engine, a cylindrical exhaust gas passage layer is provided around a catalyst having an oxidizing function. A heat exchanger comprising a cooling fluid passage layer, and the catalyst and the heat exchanger are connected so that the exhaust gas flows into the exhaust gas passage layer of the heat exchanger after passing through the catalyst. A first fin that guides the exhaust gas in the axial direction is provided in the passage layer, a second fin that guides the cooling fluid in the circumferential direction is provided in the cooling fluid passage layer, and the second fin is provided at a plurality of positions on the circumference. Divided. According to the invention of claim 2, in the heat exchanger installed in the exhaust passage of the internal combustion engine, a catalyst having an oxidizing function is directly connected to the exhaust passage upstream side of the heat exchanger, and condensed water generated in the heat exchanger is generated. Condensed water can be discharged from the exhaust passage downstream side of the heat exchanger so as not to accumulate in the heat exchanger. According to a third aspect of the present invention, in the first aspect of the present invention, the heat exchanger is disposed in the internal combustion engine in a posture in which condensed water generated in the heat exchanger can be discharged from the heat exchanger so as not to enter the catalyst. installed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiments of the invention of claims 1 and 3)
FIG. 5 is a schematic system diagram of an internal combustion engine 100 in which the invention of claim 1 is implemented. In the internal combustion engine 100, the air supplied from the air supply pipe 30 and the fuel gas supplied from the fuel supply pipe 31 are mixed in the mixer 32 to generate an air-fuel mixture, and the opening degree of the throttle 33 is adjusted. The supply amount of the air-fuel mixture to the internal combustion engine body 34 is adjusted. The air-fuel mixture burns in a combustion chamber (not shown) provided in the internal combustion engine body 34,
The exhaust gas 20a is discharged from the exhaust pipe 5 connected to the internal combustion engine body 34.

The exhaust pipe 5 is provided with a heat exchanger 10 with a catalyst. In this heat exchanger 10 with catalyst, the catalyst 2 is provided on the upstream side of the flow of exhaust gas from the heat exchanger 3. Catalyst 2
As an oxidation catalyst having an oxidizing function, a three-way catalyst, NO _X
A storage catalyst or the like can be adopted. Exhaust gas 20a including high temperatures and harmful components (NO _X) is, next to the exhaust gas 20b containing no harmful components at a low temperature by passing through the catalyst-heat exchanger 10, is discharged to the outside air via a silencer 4.

FIG. 1 is a perspective view in which a part of the heat exchanger with catalyst 10 is longitudinally cut. As shown in FIG. 1, the heat exchanger with catalyst 10 has a structure in which a cylindrical heat exchanger 3 surrounds a cylindrical catalyst 2 having an oxidizing function with a cylindrical heat insulating material 6 interposed therebetween. .

The cylindrical heat exchanger 3 is provided with a first exhaust passage layer 11, a first cooling water passage layer 13, a second exhaust passage layer 12, and a second cooling water passage layer 14 in this order from the inner peripheral side. . The first exhaust passage layer 11 is provided with corrugated plate fins (fins 15) that guide the exhaust gas in the longitudinal direction of the cylinder.

The fins 15 are divided at four locations on the circumference, and the four fins 15 are annularly arranged in the first exhaust passage layer 11. The fins 15 are the first exhaust passage layer 11
The inner peripheral side wall and the outer peripheral side wall forming the above may be sandwiched so as not to move in the circumferential direction within the first exhaust passage layer 11, but the adjacent fins 15 may be pressed against each other.

In any case, by keeping the fins 15 in contact with the outer peripheral side wall, heat transfer between the exhaust gas and the cooling water in the first cooling water passage layer 13 can be smoothly performed. Is preferred. The number of pieces of the fin 15 (the number of divided portions) may be set in consideration of the ease of manufacturing, and the shape and the central angle (for four pieces, about 90 degrees, 3
If it is a piece, it will be about 120 degrees) and so on.

The inner peripheral side wall of the second exhaust passage layer 12 is in contact with the first cooling water passage layer 13 (which will be described later), and the outer peripheral side wall is the second side.
It is in contact with the cooling water passage layer 14 (described later). The second exhaust passage layer 12 is divided into four regions. This is a vertical side view of the heat exchanger 10 with a catalyst.
It demonstrates using FIG. 4 which is sectional drawing.

As shown in FIG. 2, the second exhaust passage layer 12 is
Four dividing parts 19a, 19b, 19c and 19 on the circumference
It is divided by d. Both ends of the four second exhaust passage layers 12 extending parallel to the central axis 37 (FIG. 4) are integrally fixed to the barriers 22 and 36 shown in FIG. Further, the first exhaust passage layer 11 and the second exhaust passage layer 12 are communicated with each other by the communicating portions 35 provided at a plurality of places (for example, four places) on the circumference,
The exhaust gas 20b purified by the catalyst 2 and cooled by the heat exchanger 3 is discharged from the exhaust pipe 38.

As shown in FIG. 2, fins 16 (FIG. 2) extending in parallel with the central axis 37 are provided in the second exhaust passage layer 12 similarly to the fins 15. The fin 16 is the second
The exhaust passage layer 12 is in contact with both the inner peripheral side wall and the outer peripheral side wall, and facilitates heat exchange with the cooling water in the first cooling water passage layer 13 on the inner peripheral side, and the outer peripheral side on the outer peripheral side. The heat exchange with the cooling water in the second cooling water passage layer 14 is facilitated.

The first cooling water passage layer 13 is provided with corrugated plate fins (fins 17) extending in the circumferential direction. As shown in FIG. 2, the fins 17 are divided along the second exhaust passage layer 12 at four locations on the circumference.

Further, the second cooling water passage layer 14 is provided with fins 18 extending in the circumferential direction similarly to the fins 17. Like the fin 17, the fin 18 also has the second exhaust passage layer 1
It is divided at 4 points along the circumference along the line 2.

FIG. 3 is a front view of the heat exchanger with catalyst 10 in which the illustration of the cylindrical side wall of the outermost shell of the heat exchanger 3 of the heat exchanger with catalyst 10 is omitted. In FIG. 3, the flow of the cooling water in the second cooling water passage layer 14 is mainly shown in detail.

The low temperature cooling water 21a is supplied from the cooling water supply pipe 7 to the second cooling water passage layer 14 in the heat exchanger 10 with catalyst. The cooling water 21a can penetrate from the second cooling water passage layer 14 into the first cooling water passage layer 13 through the dividing portions 19a to 19d provided at four locations on the circumference.

The cooling water in the second cooling water passage layer 14 flows along the plurality of circumferentially extending fins 18 as indicated by thin arrows (FIG. 3). On the way, the cooling water is separated by the dividing portion 19a.
At ~ 19d, the cooling water flows in the direction in which the central axis 37 extends and approaches the cooling water discharge pipe 8 while increasing the temperature. The cooling water is transferred from the high-temperature exhaust gas in the first exhaust passage layer 11 and the second exhaust passage layer 12 to reach the cooling water on the way to the cooling water discharge pipe 8, and the temperature of the cooling water 21b is raised. Is discharged from the cooling water discharge pipe 8. When exchanging heat with the exhaust gas, the cooling water is preferably supplied to the catalyst-equipped heat exchanger 10 so as to form a counterflow with the exhaust gas from the viewpoint of heat exchange efficiency.

In the process of purifying the exhaust gas 20a in the heat exchanger with catalyst 10 and lowering the temperature thereof, the water content contained in the exhaust gas 20a is condensed, and in the first exhaust passage layer 11 and the second exhaust passage layer 12. Condensed water is produced.

As shown in FIG. 5, the heat exchanger 10 with a catalyst is used.
Is installed in the internal combustion engine 100 so that the exhaust gas 20a flows in the vertical direction inside the heat exchanger 3, the generated condensed water is smoothly discharged through the drain pipe 9 shown in FIG. Accumulation in the heat exchanger 3 can be avoided.

As described above, the heat exchanger with catalyst 10 can prevent condensed water from accumulating in the heat exchanger 3, so that the condensed water causes impurities to adhere to the first exhaust passage layer 11 and the first exhaust passage layer 11. (2) It is possible to prevent clogging that hinders the passage of exhaust gas in the exhaust passage layer 12.

In the heat exchanger with catalyst 10 shown in FIGS. 1 to 4, there are two passages for passing exhaust gas and cooling water, respectively.
Although the example in which the layers are provided is shown, it is configured so that the exhaust gas can be sufficiently purified and the temperature can be lowered. In other words, the passages for passing the exhaust gas and the cooling water need not be of a multi-layer type, but may have one layer at a time.

If a cylindrical heat insulating material 6 is provided between the catalyst 2 and the heat exchanger 3 and the first exhaust passage layer 11 is disposed adjacent to the outer peripheral wall of the heat insulating material 6 as shown in FIG. The temperature of the exhaust gas in the first exhaust passage layer 11 is lowered by the low temperature cooling water in the first cooling water passage layer 13, but the temperature of the catalyst 2 is lowered by the cooling water in the first cooling water passage layer 13. It is possible to suppress the deterioration of the catalyst 2 and prevent the reduction of the purifying action of the catalyst 2.

In the heat exchanger with catalyst 10 shown in FIGS. 1 to 4, fins 15 and 16 are provided so that the exhaust gas flows parallel to the central axis 37, and fins 17 and 16 allow the cooling water to flow in the circumferential direction. Although 18 is provided, each fin may be provided so that the exhaust gas and the cooling water flow in parallel.

The size of the heat exchanger with catalyst 10 is set, for example, to a length of about 20 cm and a diameter of about 15 cm.
The insides of the second exhaust passage layers 11, 12 and the insides of the first and second cooling water passage layers 13, 14 are partitioned. These dimensions are arbitrarily set within a range in which purification processing and temperature reduction processing of all exhaust gas discharged can be performed.

(Embodiment of the Invention of Claims 2 and 3) FIG.
3 is a schematic system diagram of an internal combustion engine 200 that implements the invention of claim 2. FIG. The configuration of the internal combustion engine 200 on the upstream side of the exhaust pipe 5 is exactly the same as the configuration of the internal combustion engine 100 in FIG. 5, except for the configuration of the heat exchanger 41 with catalyst provided in the exhaust passage 40.

As shown in FIG. 6, a heat exchanger 41 with a catalyst is provided.
Indicates that the catalyst 25 is on the upstream side of the exhaust gas flow in the heat exchanger 26.
Is integrally fixed in series. High temperature flowing in the exhaust pipe 5
And NO _XThe exhaust gas 24a containing harmful components such as
5 is purified, and the heat exchanger 26 lowers the temperature.
Downstream of 26, it hits the barrier 42 and inverts, and heats the catalyst 25 and heat.
A silencer 27 is integrally fixed to the side wall of the exchanger 26.
Then, the exhaust gas 24b is discharged to the atmosphere.

Low temperature cooling water 29a is supplied to the heat exchanger 26 via a cooling water supply pipe 43. The cooling water 29a is
In the heat exchanger 26, heat is transferred from the exhaust gas to raise the temperature, and the high temperature cooling water 29b is discharged through the cooling water discharge pipe 44.

A drain pipe 28 is provided on the barrier 42.
Condensed water generated in the heat exchanger 26 is drained by gravity to the drain pipe 2
8 is discharged to the outside so that it does not accumulate in the heat exchanger 26.

[0031]

According to the first aspect of the present invention, the heat exchanger with catalyst 10 is provided with the first and second exhaust passage layers 11 centering around the catalyst 2.
12 (exhaust gas passage layer) and the first and second cooling water passage layers 1
3 and 14 (cooling fluid passage layer) to form a layer,
Fins 15 are provided in the second exhaust passage layers 11 and 12, respectively.
16 (first fin) is provided, and fins 17 and 18 (second fin) are provided in the first and second cooling water passage layers 13 and 14, respectively.
Since the fins are provided, the exhaust gas purified by the catalyst 2 can efficiently exchange heat with the cooling water in the heat exchanger 3, and improvement of exhaust heat efficiency can be expected.

Further, the heat exchanger with catalyst 10 can be downsized because the catalyst 2 and the heat exchanger 3 are formed concentrically, and the installation space of the internal combustion engine 100 can be reduced. it can.

In the second aspect of the present invention, the condensed water generated by the condensation of the water contained in the exhaust gas is the heat exchanger 2.
The condensed water can be discharged from the exhaust passage downstream side of the heat exchanger 26 so as not to accumulate in the heat exchanger 26 (the heat exchanger 26 is inclined or vertically with the exhaust passage downstream side of the heat exchanger 26 facing downward). Therefore, it is possible to provide the catalyst-equipped heat exchanger 41 in which the catalyst 25 is directly connected to the upstream side of the heat exchanger 26 without clogging the heat exchanger 26 and the size is reduced.

In the invention of claim 3, the heat exchanger with catalyst 10 according to the invention of claim 1 can be discharged from the heat exchanger 3 so that condensed water generated in the heat exchanger 3 does not enter the catalyst 2. 5 (in FIG. 5, the heat exchanger with catalyst 10 is tilted so that only condensed water is discharged from the drain pipe 9 by gravity from the upstream side of the exhaust passage in the heat exchanger 3;
Or vertical), impurities are less likely to be accumulated in the heat exchanger 3 and clogging can be prevented, so that deterioration of the function of the heat exchanger 3 can be avoided.

[Brief description of drawings]

FIG. 1 is a perspective view in which a part of a heat exchanger with a catalyst according to the invention of claim 1 is longitudinally cut.

FIG. 2 is a vertical sectional side view of the heat exchanger with catalyst according to the invention of claim 1.

FIG. 3 is a front view of the heat exchanger with catalyst in which the illustration of the cylindrical side wall of the outermost shell of the heat exchanger is omitted.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a schematic system diagram of an internal combustion engine that implements the invention of claim 1.

FIG. 6 is a schematic system diagram of an internal combustion engine that implements the invention of claim 2.

FIG. 7 is a schematic system diagram of a conventional internal combustion engine having a catalyst and a heat exchanger in an exhaust passage.

[Explanation of symbols]

1 Exhaust Passage 2 Catalyst (Claim 1) 3 Heat Exchanger (Claim 1) 4 Silencer (Claim 1) 5 Exhaust Pipe 6 Insulation 7 Cooling Water Supply Pipe 8 Cooling Water Discharging Pipe 9 Drain Pipe (Claim 1) 10 Heat Exchanger with Catalyst 11,12 First and Second Exhaust Passage Layers (Exhaust Gas Passage Layer) 13,14 First and Second Cooling Water Passage Layers (Cooling Fluid Passage Layer) 15,16 Fins (First Fins) 17, 18 Fins (2nd fin) 19a-19d Dividing parts 20a, 20b Exhaust gas 21a, 21b Cooling water 25 Catalyst (Claim 2) 26 Heat exchanger (Claim 2) 27 Silencer (Claim 2) 28 Drain pipe (Claim 2) 29a, 29b Cooling water 30 Air supply pipe 31 Fuel supply pipe 32 Mixer 33 Throttle 34 Internal combustion engine body 37 Central shaft 38 Exhaust pipe 40 Exhaust passage 41 Heat exchanger with catalyst (Claim 2) 43 Cooling water Supply tube 44 the cooling water discharge pipe 100, 200 an internal combustion engine

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F28F 1/20 F28F 1/20 1/30 1/30 A 1/40 1/40 JN 1/42 1 / 42 E 17/00 501 17/00 501D F Term (reference) 3G004 AA06 BA06 DA23 3G091 AA06 AB02 AB03 AB06 BA05 BA14 BA15 BA19 BA36 BA39 CA08 3L103 AA03 AA05 AA35 BB17 CC02 CC27 DD10 DD37 DD42 DD44 DD62

Claims (3)

[Claims] 1. A heat exchanger installed in an exhaust passage of an internal combustion engine, wherein a heat exchanger composed of a cylindrical exhaust gas passage layer and a cooling fluid passage layer is arranged around a catalyst having an oxidizing function, and exhaust gas is A catalyst and a heat exchanger are connected so as to flow into the exhaust gas passage layer of the heat exchanger after passing through the catalyst, and a first fin for guiding the exhaust gas in the axial direction is provided in the exhaust gas passage layer. A heat exchanger with a catalyst for an internal combustion engine, characterized in that a second fin for guiding the cooling fluid in the circumferential direction is provided in the cooling fluid passage layer, and the second fin is divided at a plurality of locations on the circumference. . 2. In a heat exchanger installed in an exhaust passage of an internal combustion engine, a catalyst having an oxidizing function is directly connected to an upstream side of the exhaust passage of the heat exchanger, and condensed water generated in the heat exchanger is used as the heat exchanger. A heat exchanger with a catalyst for an internal combustion engine, wherein condensed water can be discharged from a downstream side of an exhaust passage of the heat exchanger so as not to accumulate in the exchanger. 3. The heat exchanger according to claim 1, wherein the heat exchanger is installed in the internal combustion engine in a posture in which condensed water generated in the heat exchanger can be discharged from the heat exchanger so as not to enter the catalyst. Heat exchanger with catalyst for internal combustion engine.