JPS6285111A - Exhaust system structure for engine - Google Patents

Abstract

PURPOSE:To enable condensed water to be discharged positively by allowing an exhaust passage in the downstream side of a heat exchanger to be turned over upward so as to provide a condensed water drain mechanism at the lowest point of a contrarotating section in a device where a heat exchanger which recovers exhaust gas heat, is provided in an exhaust gas passage. CONSTITUTION:An exhaust manifold heat exchanger 2 is provided in the upper portion of the side surface of an engine main body 1, where a water pipe is allowed to encircle the outer periphery of the exhaust manifold so as to allow exhaust gas to flow opposite to a coolant flow, and a heat exchanger 3 which permits heat to be exchanged between exhaust gas and water, is provided behind the engine main body 1 which it is arranged in a place lower than the above said heat exchanger 2. The heat exchanger 3 is tilted down backward allowing an exhaust port 3c at the lower end of the titled plate to be connected with an exhaust pipe 6a which extends downward. An exhaust pipe line 6b is branched from the halfway of the exhaust pipe 6a allowing the pipe line 6b to be connected with a silencer 8 which is provided just above the heat exchanger 3, besides, a condensed water drain mechanism 7 is connected with the lowest end of the exhaust pipe 6a.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust system structure for an engine that is provided with a heat exchanger for exchanging heat between exhaust gas and water to recover exhaust heat.

(Prior technology) Engine exhaust heat is recovered for heating or P1 to P2
In equipment used as a heat source for a fuel circuit, the exhaust system structure of an engine equipped with a heat exchanger for exhaust heat recovery has conventionally been such that the exhaust manifold is covered with a water jacket, as shown in Japanese Utility Model Application Publication No. 1988-1911. For those with an enclosed configuration, in other words, the exhaust manifold is surrounded by a heat exchange case without interfering with the flow of gas inside the exhaust manifold to form a closed space, and the heat transfer fluid flows into and out of this closed space. It is known that Shino was configured to do so.

By the way, in the exhaust manifold as a heat exchanger, the exhaust gas is cooled and moisture in the exhaust gas tends to condense.In this case, highly acidic condensed water is generated, and if this collects in the exhaust manifold, it will damage the inner wall of the exhaust manifold. (It is susceptible to corrosion and holes are easily formed in the wall.Also, in order to increase the heat recovery effect,
A heat exchanger is further installed on the exhaust downstream side of the exhaust manifold (
However, in this case, as a result of heat recovery in a heat exchanger, a large amount of condensed water is likely to be generated, and the above problem becomes more pronounced.

If there is a hole in the wall of the exhaust manifold or heat exchanger, water for heat exchange may flow into the engine through the exhaust manifold, or exhaust gas may enter the water circuit.

In addition, the exhaust manifold, heat exchanger, and 4-no-illen υ will be connected in sequence to the exhaust passage, but the condensed water generated in the heat exchanger should not flow into the silencer and corrode it. On the other hand, care must be taken to prevent condensed water generated within the silencer from flowing back into the heat exchanger, etc. on the upstream side of the exhaust gas.

(Object of the Invention) The present invention has been developed in view of the above-mentioned conventional problems. Even if condensed water is generated inside a heat exchanger, it is discharged without accumulating it inside, and , can prevent condensed water from flowing into the silencer, and can also prevent condensed water from flowing back into the heat exchanger from the silencer, avoiding corrosion of these parts and improving engine reliability. The present invention provides an engine exhaust system structure that can be improved.

(Structure of the Invention) The present invention provides a heat exchanger for exchanging heat between the exhaust gas and water in the exhaust passage of one engine in an engine exhaust system structure provided with a heat exchanger for recovering exhaust heat. The exhaust passage on the flow side of this heat exchanger is extended downward, and then it is reversed and extended upward, and the exhaust passage is connected to the tip of the exhaust passage, and the exhaust passage between the heat exchanger and the silencer is connected to the lowest part of the exhaust passage between the heat exchanger and the silencer. It is equipped with a condensed water drain mechanism.

With this configuration, even if condensed water occurs in the heat exchanger, it will not accumulate inside the heat exchanger and will be discharged to the outside through the condensed water drain mechanism, and will also prevent condensed water from flowing into the silencer. This prevents the condensed water generated in step E from flowing back into the heat exchanger.

(Example) Fig. 1, Fig. 2, and Fig. 3 respectively show the rear, left side, and (:1 side) of an engine embodying the present invention.
1 is an engine body, 2 is an exhaust manifold heat exchanger that is provided above the side surface of the engine body 1 and has a water passage surrounding the outer periphery of the exhaust manifold, and the exhaust and cold water flow in countercurrent flow; 3 is the exhaust manifold mentioned above; This heat exchanger is installed on the downstream side of the exhaust gas of the heat exchanger 2 and performs heat exchange between the exhaust gas and water. Moreover, the connection part 4 between the heat exchanger 3 and the exhaust manifold heat exchanger 2 is located on one side of the engine body 1, and the exhaust downstream part of the heat exchanger 3 is tilted downward. I'm letting you do it. The connecting portion 4 is constructed by connecting flanges 4a and 4b provided on each of the exhaust manifold heat exchanger 2 and the heat exchanger 3 with holes 5 to 5.

Further, an exhaust pipe 68 extending downward is connected to the exhaust pipe 68 provided at the lower end of the slope of the heat exchanger 3, and an exhaust pipe line 6b is connected to the exhaust pipe 68 branching from the middle of the exhaust pipe 6a. has been done. 7 is next to a condensed water drain n which is quickly connected to the lowermost end of the IF trachea 6a, and 8 is a silencer provided above the heat exchanger 3 through which exhaust gas flows through the lλ trachea passage 6b.

An embodiment of the configuration of the condensed water drain g1 horizontal 7 will be explained with reference to FIGS. case 7a
Float 7 C7J<'A is stored inside so that it can be lowered freely.
This float valve 0-1-7G and the drain IIF outlet lower d at the lowest end constitute a float valve. Also, case 7a
A level sensor 7e is mounted near the top of the door C to notify the level when the door C rises above a predetermined level due to a pool of drain.

Next, the structure of the heat exchanger S3 will be explained with reference to FIG. 3 and FIG. 8.

The heat exchanger 3 has an exhaust port 3a, an exhaust passage 3b, and an air outlet 3C as an exhaust passage, and a water inlet 3d, a heat exchanger core 3e, and a return water passage 3 as a cold water passage.
J3 and water outlet 3] (11' 3, and the exhaust passage 3b on the outer periphery of the heat exchanger 21a 3e is fV, r? L,
, Also, there is a water passage 3 on the outer periphery of this 1) 1 air passage 3 b.
f is the position if L/, the exhaust gas and water are configured to exchange heat in a three-layer structure 3, and lit [ ] 3
The water outlet 3g is provided at the flange 4b and connected to the flange 4a on the exhaust manifold heat exchanger 2 side.

The flow of exhaust gas is from the exhaust manifold heat exchanger 2 through the connection part 4, the exhaust port 3a of the heat exchanger 3, the exhaust passage 3b, the exhaust outlet 3C, and then the exhaust pipe 6a and the exhaust pipe line 6b.
The air passes through the inlet 8a of the Nylencer 8 and reaches the exhaust port 8b. In addition, the flow of cold fil water is transferred to the heat exchanger 3.
from the water inlet 3d to the heat exchanger core 3e, return water passage 3f,
The water flows into the exhaust manifold heat exchanger 2 via the connection part 4 through the water outlet 3g, and further flows from the exhaust manifold heat exchanger 2 to the water pipe 9a (FIG. 2) and the water pump 10.
It flows into the water outlet 1~ inside the engine main body 1 through the thermostat 1- and the water pipe line 9b, and then reaches the water outlet 9C.

Next, the operation of the configuration of the above embodiment will be explained.

cold? , II water flows in from the water inlet 3d of the heat exchanger 3, exchanges heat with 1M air in the heat exchanger 3i and the exhaust manifold heat exchanger 2, recovers the exhaust heat, and at the same time - Water flows into the jacket l- to cool the engine, and the high temperature water flows out from the water outlet 9C. This hot water is sent to a radiator installed separately from the engine and used as a heat source for indoor heating, or for pressurizing refrigerant in a heat pump refrigerant circuit driven by the output shaft of the engine body 1 (not shown). is used as a heat source for the outdoor heat exchanger in this heat pump refrigerant circuit. In this way, hot water is used as a heat source,
The cooled water flows into the water inlet 3d of the heat exchanger 3 again.

Here, in the heat exchanger 3, the high temperature exhaust gas is transferred to the exhaust population 3.
a, passes through the exhaust passage 3b, and enters the heat exchanger core 3.
Heat exchange is performed with the water flowing through the return water passage 3r and the return water passage 3r. At this time, as the gas is cooled by the cooling water passing through the heat exchanger core 3e, a large amount of condensed water is likely to be generated, but in the present invention, the generated condensed water is sequentially and reliably passed through the condensed water drain mechanism 7. is discharged to the outside. Therefore, highly acidic condensed water does not accumulate in the heat exchanger 3, and corrosion of the heat exchanger core 3e and the like can be avoided. Therefore, it is possible to prevent the heat exchanger core 3e and the like from being corroded and forming holes, thereby preventing the cooling water from leaking into the exhaust passage 3b or causing exhaust gas to flow into the water circuit.

In addition, in this embodiment, the connection part 4 between the heat exchanger 3 and the exhaust manifold heat exchanger 2 is positioned above the heat exchanger 3, and the heat exchanger 3 is placed on the exhaust stream side, that is, on the exhaust outlet 3C side. Since the cooling water is provided so as to be inclined downward, it is possible to prevent the cooling water from flowing into the exhaust manifold heat exchange 'a2 side and flowing back into the combustion chamber of the engine.

In addition, in the present invention, the exhaust system is the exhaust outlet of the heat exchanger 3 (]3C
The condensed water that has passed through the heat exchanger 3r is arranged to enter the silencer 8 through the exhaust pipe 6a extending further downward, and then through the exhaust pipe line 6b which is reversed and extends upward. The condensed water is discharged by the condensed water drain mechanism 7 at the bottom, so condensed water does not flow into the 4j eraser.
Similarly, the condensed water generated in the exhaust system 8 is discharged by the condensed water drain mechanism 7, and is prevented from flowing back into the heat exchanger 3. Therefore, the condensed water in each part of the exhaust system is Corrosion caused by accumulation of water can be prevented.

In the above embodiment, the heat exchanger 3 has a three-layer structure of exhaust gas and cold II water, but it may also have a two-layer structure in which exhaust gas and cooling water flow in opposite directions.

(Effects of the Invention) As described above, according to the present invention, a heat exchanger for exchanging heat between the exhaust gas and water is provided in the exhaust passage of the engine, and the exhaust passage on the downstream side of the heat exchanger is extended downward. , and by turning it around and extending it upward, installing a silencer at its tip, and installing a condensate drain next to the exhaust passage at the bottom of the exhaust passage between the heat exchanger and the heat exchanger, it is possible to It is possible to reliably discharge the generated condensed water to the outside.
Effectively prevents corrosion of these exhaust system parts due to condensed water (
, two things can be prevented.

[Brief explanation of drawings]

FIG. 1 shows 1 of the present invention. Figure 2 is a left side view of the engine, Figure 3 is a right side view, Figure 4 is a sectional view showing an embodiment of the condensed water drain mechanism, Figure 5 is a top view of the same, Figure 6 is a top view of the heat exchanger in the same exhaust system structure, Figure 7 is Figure 6 Vl-VI
8 is a sectional view taken along the line ■--■ in FIG. 6. 1... Engine body, 2... Exhaust manifold heat exchanger, 3... Heat exchanger, 3C... Exhaust outlet, 6a.
...Exhaust pipe, 6b...Exhaust pipe line, 7...Condensed water drain mechanism. Patent applicant Mazda Co., Ltd. Agent Patent attorney Etsushi Kotani Patent attorney Chief 1) Patent attorney Yasuo Itaya No. 1 Figure 1 Figure 5 Figure 4

Claims (1)

[Claims] 1. In an engine exhaust system structure that is equipped with a heat exchanger that recovers exhaust heat, a heat exchanger that exchanges heat between the exhaust gas and water is installed in the engine exhaust passage, and the exhaust gas downstream of this heat exchanger is The passage is extended downward, reversed and extended upward, and a silencer is connected to the tip thereof, and a condensed water drain mechanism is further provided at the bottom of the exhaust passage between the heat exchanger and the silencer. Engine exhaust system structure.