JP2019190400A - Exhaust gas heat exchanger and EGR device - Google Patents

Abstract

To discharge cleaning water for cleaning an interior of a heat exchanger from the heat exchanger unfailingly.SOLUTION: An exhaust gas heat exchanger 10 includes: an inlet side passage 21 connected to an exhaust passage 3 of an engine 1; a heat exchange part 10A in which an inlet 10A is connected to the inlet side passage 21 and which conducts heat exchange between exhaust gas from the engine 1 and a refrigerant circulating through its interior; and a second passage 22 connecting an outlet 10C of the heat exchange part 10A with the exhaust passage 3. A drain passage which guides cleaning water that has cleaned the interior of the heat exchange part 10A to the exhaust passage 3 by gravity is provided below the heat exchange part 10A.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas heat exchanger and an EGR (Exhaust Gas Recirculation) device including the exhaust gas heat exchanger.

  Patent Document 1 discloses an EGR device that includes water injection means that directly injects an appropriate amount of water to EGR gas on the inlet side of an EGR gas flow path of an EGR cooler (heat exchanger).

JP 2010-048113 A

  In the EGR device described in Patent Document 1, soot adhering in each tube of the EGR cooler can be washed away by the water vapor of water directly injected to the inlet side of the EGR gas. However, Patent Document 1 does not describe how the washed water is discharged. If water stays in the EGR cooler for a long time, the member may corrode.

  This invention is made | formed in view of said problem, and it aims at discharging | emitting the washing water for wash | cleaning the inside of a heat exchanger from a heat exchanger reliably.

  According to an aspect of the present invention, an exhaust gas heat exchanger that performs heat exchange between exhaust gas discharged from an engine and a refrigerant has a first flow path connected to the exhaust flow path of the engine, and an inlet A heat exchange section connected to the first flow path for exchanging heat between the exhaust gas from the engine and the refrigerant flowing through the interior; a second flow path for connecting the outlet of the heat exchange section and the exhaust flow path; , And a drainage channel is provided below the heat exchanging unit to guide the washing water, which has washed the inside of the heat exchanging unit, to the exhaust channel by gravity.

  According to the said aspect, the wash water which wash | cleaned the inside of a heat exchange part is discharged | emitted to an exhaust flow path through a drainage channel from a heat exchange part with gravity. Therefore, the water for washing the inside of the heat exchange unit can be reliably discharged from the heat exchange unit.

FIG. 1 is a schematic configuration diagram of an EGR apparatus including an exhaust gas heat exchanger according to an embodiment of the present invention. FIG. 2 is an internal cross-sectional view of the exhaust gas heat exchanger. FIG. 3A is a schematic diagram illustrating a state of wrinkles attached to the tube. Drawing 3B is a mimetic diagram explaining the condensed water generated between a tube and a bowl. FIG. 3C is a schematic diagram for explaining a state in which wrinkles are washed away from the tube. FIG. 4 is a view showing a modification of the exhaust gas heat exchanger. FIG. 5 is a view showing a modification of the exhaust gas heat exchanger.

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

  FIG. 1 is a schematic configuration diagram of an exhaust gas heat exchanger 10 and an EGR apparatus 100 including the exhaust gas heat exchanger 10 according to an embodiment of the present invention. The EGR device 100 includes an exhaust gas heat exchanger 10 that performs heat exchange between the exhaust gas discharged from the engine 1 and the refrigerant, and exhaust gas discharged from the engine 1 provided in the exhaust flow path 3 of the engine 1. An exhaust purification device 30 for purification. The engine 1 is, for example, a gasoline engine. Moreover, the cooling water which cools the engine 1 is used as a refrigerant | coolant.

  The exhaust gas heat exchanger 10 includes an inlet-side channel 21 as a first channel connected to the exhaust channel 3 of the engine 1 and an inlet 10B connected to the inlet-side channel 21, and exhaust gas from the engine 1. And a heat exchange part 10A for exchanging heat with the cooling water flowing inside, and a second flow path 22 for connecting the outlet 10C of the heat exchange part 10A and the exhaust flow path 3.

  The inlet-side channel 21 communicates the downstream side of the exhaust purification device 30 in the exhaust channel 3 and the inlet 10B of the heat exchange unit 10A. The inlet-side channel 21 has a gradient that decreases toward the exhaust channel 3.

  A valve device 40 is provided in the second flow path 22. The second flow path 22 includes an outlet-side flow path 22A that communicates the outlet 10C of the heat exchange unit 10A and the valve device 40, and a return flow path 22B that communicates the valve device 40 and the exhaust flow path 3. The connection portion 25 between the return flow path 22B and the exhaust flow path 3 is provided on the downstream side of the connection section 24 between the exhaust flow path 3 and the inlet side flow path 21 in the exhaust flow path 3. A flow path 3 </ b> A between the connection portion 24 and the connection portion 25 in the exhaust flow path 3 functions as a bypass flow path that bypasses the exhaust gas heat exchanger 10.

  A recirculation flow path 23 that communicates with the intake flow path 2 of the engine 1 is connected to the valve device 40. The valve device 40 controls the flow rate of the exhaust gas flowing from the outlet side channel 22A to the return channel 22B and the reflux channel 23.

  The exhaust purification device 30 includes a plurality of catalysts housed in one housing. As the plurality of catalysts, for example, a three-way catalyst is used. The exhaust purification device 30 removes hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) contained in the exhaust gas discharged from the engine 1 using a three-way catalyst.

  The EGR device 100 further includes a valve device 50 that is provided between the connection portion 24 and the connection portion 25 in the exhaust flow path 3 (flow path 3A) and serves as an on-off valve that opens and closes the exhaust flow path 3.

  Further, the valve device 50 controls the flow rate of the exhaust gas flowing out to the outside in the exhaust passage 3 by controlling the opening degree. Thereby, the flow volume of the exhaust gas which flows into the inlet side flow path 21 is controllable.

  The EGR device 100 further includes a controller 60 that controls the operation of the valve device 40 and the valve device 50. The controller 60 of the present embodiment is configured to control the operation of the engine 1 in addition to the EGR device 100. A controller that controls the EGR device 100 and a controller that controls the engine 1 may be provided separately.

  The controller 60 is composed of a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, a bus connecting these, and the like. It is also possible to configure the controller 60 with a plurality of microcomputers. The controller 60 controls the EGR device 100 when the CPU reads and executes a program stored in the ROM.

  The controller 60 receives a signal from a temperature sensor (not shown) that detects the catalyst bed temperature of the exhaust purification device 30, and a pressure sensor (not shown) that detects the introduction pressure of the exhaust gas into the reflux passage 23. A signal, a signal from a temperature sensor (not shown) for detecting the temperature of the cooling water flowing through the heat exchange unit 10A, and the like are input.

  The EGR device 100 is configured as described above, and the operation of the valve devices 40 and 50 is controlled by the controller 60 so as to operate in a mode corresponding to the state of the vehicle.

  In the EGR device 100, when the temperature of the cooling water is lower than a predetermined value (for example, immediately after the engine 1 is started, etc.), the controller 60 fully closes the valve device 50 and controls the valve device 40 to control the return flow path 23. Shut off. As a result, the exhaust gas discharged from the engine 1 to the exhaust passage 3 flows into the heat exchanging portion 10 </ b> A from the connection portion 24 through the inlet-side passage 21. That is, when the temperature of the cooling water is less than a predetermined value, the exhaust gas heat exchanger 10 functions as an exhaust heat recovery device that recovers the heat of the exhaust gas. The exhaust gas that has undergone heat exchange in the heat exchanging section 10A passes through the outlet-side flow path 22A, the valve device 40, and the return flow path 22B, is returned to the exhaust flow path 3, and is discharged to the outside.

  Thus, in the EGR device 100, when the temperature of the cooling water is less than the predetermined value, the entire amount of exhaust gas discharged from the engine 1 is passed through the heat exchange unit 10A. Thereby, the exhaust heat from the engine 1 can be recovered to the maximum extent in the heat exchange unit 10A. Therefore, the temperature of the cooling water can be quickly raised.

  Further, the EGR device 100 executes EGR control for recirculating the exhaust gas from the recirculation flow path 23 to the intake flow path 2 when a predetermined EGR execution condition is satisfied. The EGR execution condition is when the temperature of the cooling water is within a predetermined range and the engine load is within the predetermined range.

  When the EGR execution condition is satisfied, the controller 60 sets the valve device 50 to an intermediate opening degree and controls the valve device 40 to an opening degree corresponding to the required EGR amount based on the pressure in the reflux flow path 23 and the like. That is, the valve device 40 controls the flow rate of the exhaust gas flowing from the outlet side flow path 22A to the recirculation flow path 23.

  When the temperature of the cooling water is equal to or higher than the predetermined value and the EGR execution condition is not satisfied, the controller 60 sets the valve device 50 to a fully open state and sets the valve device 40 to a fully closed state. Thus, the exhaust gas discharged from the engine 1 to the exhaust flow path 3 passes through the flow path 3A, that is, bypasses the exhaust gas heat exchanger 10 and is discharged to the outside.

  Next, a specific configuration of the exhaust gas heat exchanger 10 will be described with reference to FIG. FIG. 2 is an internal cross-sectional view of the exhaust gas heat exchanger 10.

  As shown in FIG. 2, the exhaust gas heat exchanger 10 includes an exhaust gas passage 11 provided in the housing 15 through which exhaust gas guided from the inlet 10 </ b> B flows, and an exhaust gas passage 11 provided in the housing 15 in the exhaust gas passage 11. And a plurality of tubes 12 through which cooling water flows so as to exchange heat with the exhaust gas.

  The exhaust gas passage 11 is formed between the tube 12 and another adjacent tube 12 by alternately stacking a plurality of tubes 12 at intervals. In the exhaust gas passage 11, fins (not shown) are installed in order to increase the efficiency of heat exchange with the exhaust gas.

  The exhaust gas guided from the inlet-side channel 21 flows through the exhaust gas passage 11 through the inlet 10B as indicated by an arrow A in FIG.

  When the valve device 40 is open, the exhaust gas that has passed through the exhaust gas passage 11 flows to the return flow path 22B or the recirculation flow path 23 through the outlet side flow path 22A as indicated by an arrow B in FIG. .

  When the valve device 40 is closed, the exhaust gas naturally convects in the exhaust gas passage 11 and the inlet 10B.

  The cooling water flows into the plurality of tubes 12 from the cooling water flow path inlet 13 as indicated by an arrow D in FIG. When the cooling water flows through the tube 12, the cooling water exchanges heat with the exhaust gas passing through the adjacent exhaust gas passage 11 via the tube 12, and then, as shown by an arrow E in FIG. 14 flows out.

  Soot C contained in the exhaust gas adheres in the housing 15 of the exhaust gas heat exchanger 10. Such soot C can be washed away by the condensed water W generated in the housing 15. Here, the condensed water W and the soot C will be described with reference to FIGS. 3A to 3C.

  By passing the exhaust gas through the heat exchange part 10A, soot C contained in the exhaust gas adheres to the outer surface of the tube 12 and the like (see FIG. 3A). When the exhaust gas passes through the exhaust gas passage 11, if the exhaust gas is cooled to below the dew point by the cooling water flowing through the tube 12, the condensed water W is formed between the tube 12 and the soot C as shown in FIG. 3B. Generated. Condensed water W is formed by condensation of water vapor contained in the exhaust gas by cooling the exhaust gas that has entered the interior of the bag C from the small gap on the surface of the tube C near the surface of the tube 12. The condensed water W is also generated when the exhaust gas preliminarily present in the soot C deposited near the surface of the tube 12 is cooled and the water vapor in the exhaust gas is condensed.

  The soot C is an oily (hydrophobic) property in which hydrocarbons left unburned in the combustion process are aggregated and solidified through various chemical reactions. Therefore, the produced condensed water W forms a water film layer by spreading between the tube 12 and the ridge C without being absorbed by the hydrophobic ridge C. As a result, the bag C is forcibly separated from the surface of the tube 12 by the water film. And the inside of the tube 12 and the housing 15 is wash | cleaned by flowing the coffin C with the condensed water W. FIG. Thus, the condensed water W is used as cleaning water for cleaning the inside of the housing 15.

  If the condensed water W stays in the housing 15 for a long time, the housing 15 and the tube 12 may be corroded. For this reason, in the exhaust gas heat exchanger 10 of the present embodiment, the inlet 10B of the heat exchange unit 10A is installed facing downward. Accordingly, the condensed water W that has flowed along with the bowl C flows down to the bottom surface side of the housing 15 and then flows toward the lowermost side (the inlet 10B side) of the housing 15 by gravity. Further, the condensed water W is discharged from the heat exchange unit 10A to the exhaust passage 3 through the inlet side passage 21 by gravity. Thus, in the exhaust gas heat exchanger 10 of the present embodiment, the inlet-side flow channel 21 functions as a drainage channel for discharging the condensed water W.

  In the above embodiment, the inlet-side channel 21 is used as a drainage channel for discharging the condensed water W, but a drainage channel may be provided separately. Specifically, as shown in FIG. 4, a drainage channel 70 communicating with the exhaust flow path 3 may be provided below the heat exchange unit 10 </ b> A. As shown in FIG. 5, a drainage channel 170 communicating with the return channel 22B may be provided below the heat exchange unit 10A. In addition, the drainage channel 70 and the drainage channel 170 are provided so as to have a gradient that decreases toward the exhaust channel 3.

In the above embodiment, the case where the inlet 10B of the heat exchange unit 10A is installed downward has been described as an example. However, the outlet 10C may be installed downward. In this case,
The outlet side channel 22A and the return channel 22B function as a drainage channel. Also in this case, a separate drainage channel may be provided as in the configuration shown in FIGS.

  Further, when the heat exchanging portion 10A is installed horizontally, a recess or the like for storing the condensed water W is provided at the bottom of the housing 15, and a drainage channel that communicates the recess with the exhaust passage 3 or the return passage 22B. May be provided. Thereby, the condensed water W can be discharged | emitted by gravity.

  The configuration, operation, and effect of the embodiment of the present invention configured as described above will be described together.

  The exhaust gas heat exchanger 10 has a first flow path (inlet side flow path 21) connected to the exhaust flow path 3 of the engine 1 and an inlet 10B connected to the first flow path (inlet side flow path 21). A heat exchange part 10A for exchanging heat between the exhaust gas from the engine 1 and the refrigerant (cooling water) flowing inside, and a second flow path for connecting the outlet 10C of the heat exchange part 10A and the exhaust flow path 3 22. Below the heat exchanging unit 10A is a drainage channel (inlet side channel 21, outlet side channel 22A and return channel 22B, drainage) that guides washing water that has cleaned the inside of the heat exchange unit 10A to the exhaust channel 3 by gravity. A channel 70 and a drainage channel 170) are provided.

  Wash water (condensate water W) that cleans the inside of the heat exchange unit 10A is drained from the heat exchange unit 10A by gravity (inlet side channel 21, outlet side channel 22A and return channel 22B, drain channel 70, drainage). It is discharged to the exhaust passage 3 through the passage 170). Therefore, the water for washing the inside of the heat exchange unit 10A can be reliably discharged from the heat exchange unit 10A. Thereby, it can prevent that the inside of 10 A of heat exchange parts corrodes.

  In the exhaust gas heat exchanger 10, the drainage channel is the first channel (inlet side channel 21).

  In this configuration, there is no need to separately provide a drainage channel, so that the apparatus can be simplified.

  In the exhaust gas heat exchanger 10, the drainage channel is a channel different from the first channel (inlet side channel 21).

  By providing the drainage channel 70 and the drainage channel 170, the cleaning water (condensed water W) flows through a flow path that is not affected by the flow of exhaust gas, so the cleaning water (condensed water W) is quickly and reliably discharged. it can.

  The EGR device 100 includes an exhaust gas heat exchanger 10, a recirculation flow path 23 that allows the second flow path 22 and the intake flow path 2 of the engine 1 to communicate with each other, and an exhaust purification apparatus that purifies the exhaust gas discharged from the engine 1. 30. Further, the exhaust gas purification device 30 accommodates a plurality of types of catalysts in the same housing and is located upstream of the connection portion 24 with the first flow path (inlet side flow path 21) in the exhaust flow path 3. Only provided.

  By accommodating a plurality of types of catalysts in the same housing, space can be saved and piping work can be simplified. Furthermore, by providing the exhaust purification device 30 upstream of the exhaust gas heat exchanger 10 in the exhaust flow path 3, high-temperature exhaust gas is guided, so that the reduction performance can be exhibited quickly.

  In the EGR device 100, an exhaust flow is provided between the connection part 24 of the exhaust flow path 3 to the first flow path (inlet side flow path 21) and the connection part 25 to the second flow path 22 (flow path 3 </ b> A). An on-off valve (valve device 50) for opening and closing the passage 3 is provided, and the on-off valve (valve device 50) is configured to provide an exhaust flow when the temperature of the refrigerant flowing through the exhaust gas heat exchanger 10 is less than a predetermined value. The path 3 is closed.

  When the temperature of the refrigerant flowing inside the exhaust gas heat exchanger 10 is less than a predetermined value, the exhaust flow path 3 is closed, so that the total amount of exhaust gas flowing through the exhaust flow path 3 is reduced to the exhaust gas heat exchanger 10. Flowing into. As a result, exhaust heat of exhaust gas can be recovered to the maximum, so that the temperature of the refrigerant can be increased efficiently.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  The EGR device 100 may be applied not only to a gasoline engine but also to a diesel engine.

  Further, in place of the valve device 40, a valve for controlling the flow rate of the exhaust gas flowing through the reflux channel 23 is provided in the reflux channel 23, and the flow rate of the exhaust gas flowing through the second channel 22 is set in the second channel 22. A valve to be controlled may be provided.

DESCRIPTION OF SYMBOLS 100 EGR apparatus 1 Engine 2 Intake flow path 3 Exhaust flow path 10 Exhaust gas heat exchanger 10A Heat exchange part 10B Inlet 10C Outlet 21 Inlet side flow path (1st flow path, drainage channel)
22 2nd flow path 22A Outlet side flow path (2nd flow path, drainage channel)
22B Return channel (second channel, drainage channel)
23 Reflux Channel 24 Connection Portion 25 Connection Portion 30 Exhaust Purification Device 40 Valve Device 50 Valve Device (Open / Close Valve)
60 Controller 70 Drainage channel 170 Drainage channel

Claims (7)

An exhaust gas heat exchanger for exchanging heat between the exhaust gas discharged from the engine and the refrigerant,
A first flow path connected to the exhaust flow path of the engine;
An inlet connected to the first flow path, and a heat exchanging section for exchanging heat between the exhaust gas from the engine and the refrigerant flowing inside,
A second flow path connecting the outlet of the heat exchange section and the exhaust flow path,
Below the heat exchanging unit, a drainage channel is provided that guides washing water that has washed the inside of the heat exchanging unit to the exhaust passage by gravity.
An exhaust gas heat exchanger characterized by that. The exhaust gas heat exchanger according to claim 1,
The drainage channel is the first channel.
An exhaust gas heat exchanger characterized by that. The exhaust gas heat exchanger according to claim 1,
The drainage channel is a channel different from the first channel.
An exhaust gas heat exchanger characterized by that. An exhaust gas heat exchanger according to claim 3,
The drainage channel is connected to the exhaust channel.
An exhaust gas heat exchanger characterized by that. An exhaust gas heat exchanger according to any one of claims 1 to 4,
The second flow path is connected to a return flow path that leads to an intake flow path of the engine.
An exhaust gas heat exchanger characterized by that. An exhaust gas heat exchanger according to any one of claims 1 to 5;
A recirculation flow path for communicating the second flow path and the intake flow path of the engine;
An exhaust purification device for purifying exhaust gas exhausted from the engine,
The exhaust emission control device is provided with only a plurality of types of catalysts in the same housing and at an upstream side of a connection portion with the first flow path in the exhaust flow path.
An EGR device characterized by that. The EGR device according to claim 6,
An opening / closing valve that opens and closes the exhaust passage is provided between the connection portion of the exhaust passage with the first passage and the connection portion of the second passage,
The on-off valve closes the exhaust passage when the temperature of the refrigerant flowing through the exhaust gas heat exchanger is less than a predetermined value.
An EGR device characterized by that.

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