JP2023078999A - Exhaust heat recovery device - Google Patents

Abstract

To provide an exhaust heat recovery device capable of simplifying a configuration of a valve.SOLUTION: An exhaust heat recovery device includes: a heat exchange part exchanging heat between exhaust gas of an internal combustion engine and cooling water; a main flow passage having an introduction port for introducing exhaust gas, a main discharge port for discharging exhaust gas to outside and a supply port for supplying exhaust gas to the heat exchange part; and a valve train disposed in the main flow passage and controlling supply amount of exhaust gas from the main flow passage to the heat exchange part. The valve train includes: a main valve controlling a flow rate of exhaust gas to the main discharge port; a sub valve for controlling an opening of the supply port; and a shaft part to which the main valve and the sub valve are attached and that rotates the main valve and the sub valve.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to exhaust heat recovery devices.

2. Description of the Related Art An exhaust heat recovery device is known that recovers the heat of exhaust gas in an internal combustion engine for automobiles with cooling water and circulates it to the internal combustion engine as EGR (exhaust gas recirculation) gas (see Patent Document 1).

In this exhaust heat recovery device, the amount of EGR gas flowing into the heat exchanger is controlled by a valve provided in the main exhaust gas flow path, and the EGR gas amount is controlled by another valve provided in the EGR flow path. there is

JP 2017-82706 A

In the exhaust heat recovery device described above, two valves are independently provided in separate flow paths. Therefore, the mounting structure of the valve and the control mechanism tend to become complicated.

One aspect of the present disclosure aims to provide an exhaust heat recovery device that can simplify the configuration of the valve.

One aspect of the present disclosure includes a heat exchange unit that exchanges heat between an exhaust gas of an internal combustion engine and cooling water, an inlet for introducing the exhaust gas, a main outlet for discharging the exhaust gas to the outside, a supply port for supplying exhaust gas to the heat exchange section; and a main flow path disposed inside the main flow path and configured to adjust the amount of exhaust gas supplied from the main flow path to the heat exchange section. and a valve mechanism.

The valve mechanism includes a main valve configured to adjust the flow rate of the exhaust gas to the main outlet, a sub-valve configured to adjust the opening of the supply port, and the main valve and the sub-valve. and a shaft configured to rotate the main valve and the sub-valve by axial rotation.

According to such a configuration, the flow rate of the exhaust gas supplied to the EGR passage can be adjusted by the main valve and the sub-valve attached to the common shaft portion. Therefore, the configuration of the valve can be simplified.

In one aspect of the present disclosure, the sub-valve may rotate integrally with the main valve via the shaft. According to such a configuration, since the main valve and the sub-valve can be controlled simultaneously, the simplification of the valve configuration can be promoted.

In one aspect of the present disclosure, the heat exchange section may be arranged to surround at least part of the main flow path from the radial outside. According to such a configuration, the flow path from the main flow path to the heat exchange section can be shortened, and the size of the exhaust heat recovery device can be reduced.

In one aspect of the present disclosure, the sub-valve may face the shaft in the radial direction of the shaft. With such a configuration, the opening area of the supply port provided in the main flow path can be increased. As a result, the maximum circulation amount of exhaust gas can be increased.

One aspect of the present disclosure may further include an EGR flow path through which the exhaust gas that has passed through the heat exchange portion flows. No valve may be present in the EGR flow path. According to such a configuration, since there is no shield in the EGR passage, it is possible to increase the maximum circulation amount of the exhaust gas.

1A and 1B are schematic diagrams showing the arrangement of the exhaust heat recovery device of the embodiment. 2A is a schematic cross-sectional view of an embodiment exhaust heat recovery device in EGR mode, and FIG. 2B is a schematic perspective view of a valve mechanism in the exhaust heat recovery device of FIG. 2A. 3 is a schematic front view of a heat exchange section in the exhaust heat recovery device of FIG. 2A. FIG. 4A is a schematic cross-sectional view of the exhaust heat recovery device of FIG. 2A in an intermediate state, and FIG. 4B is a schematic perspective view of a valve mechanism in the exhaust heat recovery device of FIG. 4A. 5A is a schematic cross-sectional view of the exhaust heat recovery device of FIG. 2A in non-EGR mode, and FIG. 5B is a schematic perspective view of a valve mechanism in the exhaust heat recovery device of FIG. 5A. 6A and 6B are schematic cross-sectional views of an exhaust heat recovery device of an embodiment different from that of FIG. 2A. 7A is a schematic front view of a valve mechanism in an EGR mode of an exhaust heat recovery device of an embodiment different from that of FIG. 2A, and FIG. 7B is a schematic side view of the valve mechanism of FIG. 7C is a schematic front view of the valve mechanism of FIG. 7A in an intermediate state, FIG. 7D is a schematic side view of the valve mechanism of FIG. 7C, and FIG. 7E is the valve of FIG. 7A in non-EGR mode. 7F is a schematic side view of the valve mechanism of FIG. 7E; FIG.

Embodiments to which the present disclosure is applied will be described below with reference to the drawings.
[1. First Embodiment]
[1-1. composition]
An exhaust heat recovery device 1 shown in FIGS. 1A and 1B is provided in an exhaust gas flow path of an internal combustion engine 101 .

The exhaust heat recovery device 1 purifies the exhaust gas. In addition, the exhaust heat recovery device 1 recovers part of the heat of the purified exhaust gas in cooling water, and then circulates the cooled exhaust gas to the internal combustion engine 101 as EGR gas.

The internal combustion engine 101 provided with the exhaust heat recovery device 1 includes, for example, a gasoline engine or a diesel engine used in automobiles. Exhaust gas that has not been circulated as EGR gas in the exhaust heat recovery device 1 passes through the sub-muffler 104 and the main muffler 105 on the downstream side and is discharged outside the system.

The exhaust heat recovery device 1 may be arranged downstream of an SC (Start Catalyst) catalytic device 102 as shown in FIG. 1A. In this case, the exhaust heat recovery device 1 functions as a UF (Under Floor) catalytic device. Also, the exhaust heat recovery device 1 may be arranged upstream of the UF catalytic device 103 as shown in FIG. 1B. In this case, the exhaust heat recovery device 1 functions as an SC catalytic device.

As shown in FIG. 2A, the exhaust heat recovery device 1 includes a catalyst case 2, a catalyst 3, a heat exchange section 4, a main flow path 5, an EGR flow path 6, a valve mechanism 7, and an actuator 8. .

<Catalyst case>
The catalyst case 2 is a tubular member having an internal space through which the exhaust gas G of the internal combustion engine 101 flows in the axial direction. A main flow path 5 is connected to the downstream side of the catalyst case 2 .

<Catalyst>
The catalyst 3 reforms or collects environmental pollutants in the exhaust gas G through contact with the exhaust gas G, thereby purifying the exhaust gas G.

The catalyst 3 is housed in the catalyst case 2 . The catalyst 3 has, for example, a three-dimensional shape (honeycomb shape, for example) in which a plurality of partition plates extending in the axial direction of the catalyst case 2 are arranged in a grid pattern.

<Heat exchange part>
The heat exchange portion 4 is a portion that exchanges heat between the exhaust gas G of the internal combustion engine 101 and the cooling water.

The heat exchange portion 4 is arranged so as to surround at least part of the main flow path 5 from the outside in the radial direction (that is, the direction intersecting the flow direction of the exhaust gas G). As shown in FIG. 3, the heat exchange section 4 has an annular shape with the main flow path 5 inserted therein. The heat exchange portion 4 has a first water passage 41 , a second water passage 42 , and a heat transfer member 43 .

Cooling water for cooling the exhaust gas G is supplied into the heat exchange portion 4 from one of the first water passage port 41 and the second water passage port 42, and after passing through the heat transfer member 43, flows through the first water passage port 41 and the second water passage. It is discharged from the other of the water inlets 42 .

The heat transfer member 43 has a plurality of heat transfer plates arranged side by side along the flow direction of the exhaust gas G in the main passage 5 . The heat transfer plate exchanges heat between the exhaust gas G in contact with one surface and the cooling water in contact with the other surface. The heat transfer plate surrounds the main flow path 5 from the radial outside. A tube having a plurality of fins may be used instead of the heat transfer plate.

The exhaust gas G is supplied into the heat exchange section 4 from the supply port 53 of the main flow path 5 . Exhaust gas G after heat exchange is discharged from inside the heat exchange portion 4 to the EGR flow path 6 and sent to the internal combustion engine 101 via the EGR flow path 6 .

<Main flow path>
The main flow path 5 shown in FIG. 2A is a pipe having an inlet 51 , a main outlet 52 , a supply port 53 and a valve housing portion 54 .

The inlet 51 introduces the exhaust gas G that has passed through the catalyst 3 into the main flow path 5 . The main discharge port 52 discharges the exhaust gas G to the outside of the exhaust heat recovery device 1 . In this embodiment, the inlet 51 and the main outlet 52 are arranged to face each other.

That is, the flow direction of the exhaust gas G at the introduction port 51 and the flow direction of the exhaust gas G at the main discharge port 52 are parallel. Furthermore, the center of the introduction port 51 overlaps the main discharge port 52 when viewed from the flow direction of the exhaust gas G in the introduction port 51 . Note that the flow direction of the exhaust gas G may be curved within the main flow path 5 .

The supply port 53 supplies the exhaust gas G to the heat exchange section 4 . The supply port 53 is provided in the valve accommodating portion 54 . The supply port 53 is provided on the inner peripheral surface of the main flow path 5 and does not face the inlet 51 and the main discharge port 52 .

The valve accommodating portion 54 is a portion where the valve mechanism 7 is arranged, and has a larger diameter than other portions of the main flow passage 5 . Specifically, as shown in FIG. 2B , the valve accommodating portion 54 has a spherical truncated shape in which the upstream side and the downstream side in the flow direction of the exhaust gas G are cut from a true sphere. A supply port 53 is provided on the side surface of the valve housing portion 54 .

<EGR flow path>
The EGR passage 6 is a pipe through which the exhaust gas G that has passed through the heat exchange portion 4 flows. The EGR flow path 6 connects the outlet of the exhaust gas G of the heat exchange section 4 and the EGR inlet of the internal combustion engine 101 . In this embodiment, a valve for adjusting the flow rate of the exhaust gas G in the EGR flow path 6 does not exist in the EGR flow path 6 .

<Valve mechanism>
The valve mechanism 7 is arranged inside the main flow path 5 and configured to adjust the amount of exhaust gas G supplied from the main flow path 5 to the heat exchange section 4 . The opening of the valve mechanism 7 changes according to the mode of the exhaust heat recovery device 1 . The valve mechanism 7 has a main valve 71 , a sub-valve 72 and a shaft portion 73 .

The main valve 71 is configured to adjust the flow rate of the exhaust gas G to the main discharge port 52 . That is, the main valve 71 adjusts the degree of opening of the main flow path 5 (specifically, the valve accommodating portion 54).

The main valve 71 is disc-shaped and fixed to the shaft portion 73 . 4A and 4B from the position where the main flow passage 5 is completely closed (that is, the position where the opening degree of the main flow passage 5 is zero) shown in FIGS. 5A and 5B to the position where the opening degree of the main flow passage 5 is 100% shown in FIGS. 5A and 5B. When the main valve 71 is located at a position where the opening of the main flow passage 5 is 100%, the plate surface of the main valve 71 is parallel to the flow direction of the exhaust gas G.

The sub-valve 72 is configured to adjust the opening of the supply port 53 . The sub-valve 72 adjusts the flow rate of the exhaust gas G supplied from the main flow path 5 to the heat exchange section 4 together with the main valve 71 .

The sub-valve 72 has a band-like shape curved along the inner surface of the valve accommodating portion 54 and is fixed to the shaft portion 73 together with the main valve 71 . The sub-valve 72 rotates integrally with the main valve 71 via the shaft portion 73 . That is, the position of the sub-valve 72 relative to the main valve 71 remains unchanged regardless of the position of the main valve 71 .

4A and 4B from a position away from the supply port 53 shown in FIGS. After passing through the intermediate opening position where the supply port 53 is partially closed, it rotates until the supply port 53 shown in FIGS. 5A and 5B is completely closed (that is, the opening degree of the supply port 53 is zero).

2A and 2B, the non-EGR mode shown in FIGS. 5A and 5B, and the optional state shown in FIGS. 4A and 4B, which is an intermediate state between these two modes. It can be displaced according to the valve opening degree.

In the EGR mode, the entire amount of the exhaust gas G is supplied to the EGR passage 6 through the heat exchange section 4 . In the non-EGR mode, all of the exhaust gas G is discharged from the main discharge port 52 and no exhaust gas G is supplied to the EGR passage 6 .

Further, in the EGR mode, the sub-valve 72 is located upstream of the main valve 71 in the flow direction of the exhaust gas G. Further, the sub-valve 72 is positioned outside the valve accommodating portion 54 (specifically, upstream of the valve accommodating portion 54).

In the intermediate state, part of the exhaust gas G is supplied to the EGR passage 6 through the heat exchange section 4 and the rest of the exhaust gas G is discharged from the main discharge port 52 . The ratio between the amount of exhaust gas G supplied to the EGR passage 6 and the amount of exhaust gas G discharged from the main discharge port 52 is determined by the opening degrees of the main valve 71 and the sub-valve 72 .

The shaft portion 73 is a rod-shaped member (that is, a stem) connected to the actuator 8 . The shaft portion 73 is rotatably attached to the valve housing portion 54 . The shaft portion 73 is axially rotated by driving the actuator 8 . The axial direction of the shaft portion 73 is orthogonal to the flow direction of the exhaust gas G in the valve housing portion 54 .

The sub-valve 72 faces the shaft portion 73 in the radial direction of the shaft portion 73 . That is, the sub-valve 72 is attached to the shaft portion 73 so as to move in the circumferential direction of the shaft portion 73 . Further, the supply port 53 is provided radially outside the shaft portion 73 .

<Actuator>
Actuator 8 operates valve mechanism 7 . Specifically, the actuator 8 displaces the valve mechanism 7 by axially rotating the shaft portion 73 .

As the actuator 8, a motor driven using power such as electric power, pneumatic pressure, or hydraulic pressure, or a thermoactuator using a thermal expansion body that expands and contracts according to the temperature of the cooling water, or the like can be used.

[1-2. effect]
According to the embodiment detailed above, the following effects are obtained.
(1a) The flow rate of the exhaust gas G supplied to the EGR passage 6 can be adjusted by the main valve 71 and the sub-valve 72 attached to the common shaft portion 73 . Therefore, the configuration of the valve can be simplified.

(1b) Since the sub-valve 72 rotates integrally with the main valve 71, the main valve 71 and the sub-valve 72 can be controlled at the same time, thereby promoting simplification of the valve configuration.

(1c) By arranging the heat exchange section 4 so as to surround at least part of the main flow path 5 from the outside in the radial direction, the flow path from the main flow path 5 to the heat exchange section 4 can be shortened, and the exhaust heat recovery device 1 can be miniaturized.

(1d) The sub-valve 72 faces the shaft portion 73 in the radial direction of the shaft portion 73, so that the opening area of the supply port 53 provided in the main flow passage 5 can be increased. As a result, the maximum circulation amount of the exhaust gas G can be increased.

(1e) The maximum amount of circulation of the exhaust gas G can be increased because there is no valve that serves as a shield in the EGR flow path 6 .

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, it is needless to say that the present disclosure is not limited to the above embodiments and can take various forms.

(2a) In the exhaust heat recovery device of the above embodiment, the heat exchange section does not necessarily have to surround at least part of the main flow path from the radial outside. For example, as shown in FIG. 6A , the heat exchange section 4 may be arranged away from the main channel 5 and connected to the supply port 53 by the auxiliary channel 9 . Furthermore, as shown in FIG. 6B , the heat exchange section 4 may be arranged laterally adjacent to the main flow path 5 .

(2b) In the exhaust heat recovery device of the above embodiment, the sub-valve does not necessarily have to face the shaft in the radial direction of the shaft. For example, as shown in FIGS. 7A and 7B, the sub-valve 72 may be configured to move in a plane orthogonal to the axial direction of the shaft portion 73. As shown in FIGS. In this case, the supply port 53 to the heat exchange portion 4 is provided on the side surface of the main flow path 5 that intersects the axis of the shaft portion 73 . The sub-valve 72 moves along the side where the supply port 53 is provided.

In the EGR mode shown in FIGS. 7A and 7B, the sub-valve 72 is positioned so as not to overlap the supply port 53 and the main valve 71 is positioned to completely block the main flow path 5 . In the intermediate state shown in FIGS. 7C and 7D , the sub-valve 72 overlaps with a portion of the supply port 53 and the main valve 71 is positioned to restrict the flow rate of the main flow path 5 . In the non-EGR mode shown in FIGS. 7E and 7F, the sub-valve 72 overlaps the entire supply port 53 and the main valve 71 causes the opening of the main flow passage 5 to be 100%.

(2c) In the exhaust heat recovery device of the above embodiment, the sub-valve does not necessarily have to rotate integrally with the main valve. For example, the valve mechanism may have a configuration in which the main valve and the sub-valve rotate at different timings.

(2d) In the exhaust heat recovery device of the above embodiment, a valve for adjusting the flow rate of exhaust gas may be provided in the EGR passage.

(2e) The function of one component in the above embodiments may be distributed as multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiment may be omitted. Also, at least a part of the configuration of the above embodiment may be added, replaced, etc. with respect to the configuration of the other above embodiment. It should be noted that all aspects included in the technical idea specified by the wording in the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 1... Exhaust heat recovery device, 2... Catalyst case, 3... Catalyst, 4... Heat exchange part, 5... Main flow path,
6... EGR flow path, 7... valve mechanism, 8... actuator, 9... auxiliary flow path,
41... First water flow port, 42... Second water flow port, 43... Heat transfer member, 51... Inlet,
52...Main discharge port, 53...Supply port, 54...Valve accommodating portion, 71...Main valve,
72 Sub-valve 73 Axle 101 Internal combustion engine 102 Catalyst device
103... Catalyst device, 104... Sub-muffler, 105... Main muffler.

Claims (5)

a heat exchange unit that exchanges heat between the exhaust gas of the internal combustion engine and the cooling water;
a main flow path having an inlet for introducing the exhaust gas, a main outlet for discharging the exhaust gas to the outside, and a supply port for supplying the exhaust gas to the heat exchange section;
a valve mechanism arranged inside the main flow path and configured to adjust the supply amount of the exhaust gas from the main flow path to the heat exchange section;
with
The valve mechanism is
a main valve configured to regulate the flow of the exhaust gas to the main outlet;
a sub-valve configured to adjust the opening of the supply port;
a shaft portion to which the main valve and the sub-valve are attached and configured to rotate the main valve and the sub-valve by axial rotation;
an exhaust heat recovery device. An exhaust heat recovery device according to claim 1,
The exhaust heat recovery device, wherein the sub-valve rotates integrally with the main valve by the shaft portion. The exhaust heat recovery device according to claim 1 or 2,
The exhaust heat recovery device, wherein the heat exchange section is arranged to surround at least a portion of the main flow path from the outside in a radial direction. The exhaust heat recovery device according to any one of claims 1 to 3,
The sub-valve is an exhaust heat recovery device that faces the shaft portion in a radial direction of the shaft portion. The exhaust heat recovery device according to any one of claims 1 to 4,
further comprising an EGR flow path through which the exhaust gas that has passed through the heat exchange portion flows,
An exhaust heat recovery device in which there is no valve in the EGR flow path.

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