JP7590307B2 - Exhaust heat recovery device - Google Patents

Description

This disclosure relates to an exhaust heat recovery device.

An exhaust heat recovery device is known that recovers heat from exhaust gas in an automobile internal combustion engine using cooling water and circulates the heat to the internal combustion engine as EGR (exhaust gas recirculation) gas (see Patent Document 1).

In this exhaust heat recovery system, a valve installed in the main exhaust gas flow path controls the amount of exhaust gas flowing into the heat exchanger, and another valve installed in the EGR flow path controls the amount of EGR gas.

JP 2017-82706 A

In the above-mentioned exhaust heat recovery device, two valves are installed independently in separate flow paths. This can lead to complex valve installation structures and control mechanisms.

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

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

The valve mechanism has a main valve configured to adjust the flow rate of exhaust gas to the main exhaust port, a sub-valve configured to adjust the opening of the supply port, and a shaft portion to which the main valve and sub-valve are attached and configured to rotate the main valve and sub-valve by shaft rotation.

With this configuration, the flow rate of exhaust gas supplied to the EGR passage can be adjusted by the main valve and sub-valve attached to a common shaft portion. This simplifies the valve configuration.

In one aspect of the present disclosure, the sub-valve may rotate integrally with the main valve via the shaft. This configuration allows the main valve and the sub-valve to be controlled simultaneously, which can facilitate simplification of the valve configuration.

In one aspect of the present disclosure, the heat exchange section may be disposed so as to surround at least a portion of the main flow path from the radially outer side. With this configuration, the flow path from the main flow path to the heat exchange section can be shortened, and the exhaust heat recovery device can be made smaller.

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

One aspect of the present disclosure may further include an EGR flow passage through which exhaust gas that has passed through the heat exchanger flows. There may be no valve in the EGR flow passage. With this configuration, there is no obstruction in the EGR flow passage, so the maximum amount of exhaust gas circulating can be increased.

1A and 1B are schematic diagrams showing the arrangement of an exhaust heat recovery device according to an embodiment. FIG. 2A is a schematic cross-sectional view of an exhaust heat recovery device of an embodiment in an EGR mode, and FIG. 2B is a schematic perspective view of a valve mechanism in the exhaust heat recovery device of FIG. 2A. FIG. 3 is a schematic front view of a heat exchange section in the exhaust heat recovery device of FIG. 2A. 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 a 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 according to an embodiment different from that shown in FIG. 2A. 7A is a schematic front view of the valve mechanism in EGR mode of an exhaust heat recovery device of an embodiment different from that of FIG. 2A, FIG. 7B is a schematic side view of the valve mechanism of FIG. 7A, 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, FIG. 7E is a schematic front view of the valve mechanism of FIG. 7A in non-EGR mode, and FIG. 7F is a schematic side view of the valve mechanism of FIG. 7E.

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.
[1. First embodiment]
[1-1. Configuration]
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 a portion of the heat of the purified exhaust gas into the cooling water, and then circulates the cooled exhaust gas to the internal combustion engine 101 as EGR gas.

The internal combustion engine 101 in which the exhaust heat recovery device 1 is installed may be, for example, a gasoline engine or a diesel engine used in an automobile. Exhaust gas that is not circulated as EGR gas in the exhaust heat recovery device 1 passes through the downstream sub-muffler 104 and main muffler 105 and is discharged outside the system.

The exhaust heat recovery device 1 may be disposed downstream of the 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. The exhaust heat recovery device 1 may also be disposed 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 cylindrical member having an internal space through which exhaust gas G from the internal combustion engine 101 flows in the axial direction. A main flow passage 5 is connected to the downstream side of the catalyst case 2.

<Catalyst>
The catalyst 3 purifies the exhaust gas G by coming into contact with the exhaust gas G and reforming or capturing environmental pollutants in the exhaust gas G.

The catalyst 3 is stored in the catalyst case 2. The catalyst 3 has, for example, a three-dimensional shape (e.g., a honeycomb shape) in which multiple partition plates extending in the axial direction of the catalyst case 2 are arranged in a lattice pattern.

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

The heat exchange unit 4 is disposed so as to surround at least a portion of the main flow passage 5 from the outside in the radial direction (i.e., the direction intersecting the flow direction of the exhaust gas G). As shown in FIG. 3, the heat exchange unit 4 has a circular ring shape with the main flow passage 5 inserted therein. The heat exchange unit 4 has a first water passage port 41, a second water passage port 42, and a heat transfer member 43.

The cooling water that cools the exhaust gas G is supplied into the heat exchange section 4 from one of the first water inlet 41 and the second water inlet 42, passes through the heat transfer member 43, and is discharged from the other of the first water inlet 41 and the second water inlet 42.

The heat transfer member 43 has multiple heat transfer plates arranged side by side along the flow direction of the exhaust gas G in the main flow path 5. The heat transfer plates exchange heat between the exhaust gas G in contact with one surface and the cooling water in contact with the other surface. The heat transfer plates surround the main flow path 5 from the radial outside. Note that a tube with multiple fins may be used instead of the heat transfer plates.

The exhaust gas G is supplied to the inside of the heat exchange section 4 from the supply port 53 of the main flow passage 5. After heat exchange, the exhaust gas G is discharged from the inside of the heat exchange section 4 to the EGR flow passage 6 and is sent to the internal combustion engine 101 via the EGR flow passage 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 passage 5. The main exhaust port 52 exhausts the exhaust gas G to the outside of the exhaust heat recovery device 1. In this embodiment, the inlet 51 and the main exhaust port 52 are arranged to face each other.

In other words, the flow direction of the exhaust gas G at the inlet 51 is parallel to the flow direction of the exhaust gas G at the main exhaust outlet 52. Furthermore, the center of the inlet 51 overlaps with the main exhaust outlet 52 when viewed from the flow direction of the exhaust gas G at the inlet 51. Note that the flow direction of the exhaust gas G may be curved within the main flow passage 5.

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

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

<EGR passage>
The EGR passage 6 is a pipe through which the exhaust gas G flows after passing through the heat exchange unit 4. The EGR passage 6 connects an exhaust port of the heat exchange unit 4 for the exhaust gas G to an EGR inlet port of the internal combustion engine 101. In this embodiment, no valve for adjusting the flow rate of the exhaust gas G in the EGR passage 6 is provided in the EGR passage 6.

<Valve mechanism>
The valve mechanism 7 is disposed inside the main flow path 5, and is configured to adjust the amount of exhaust gas G supplied from the main flow path 5 to the heat exchange section 4. The opening degree of the valve mechanism 7 changes depending on 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 exhaust gas G to the main exhaust port 52. In other words, the main valve 71 adjusts the opening of the main flow path 5 (specifically, the valve housing portion 54).

The main valve 71 is disk-shaped and fixed to the shaft 73. By axial rotation of the shaft 73, the main valve 71 rotates from a position where the main flow passage 5 is completely blocked (i.e., a position where the opening of the main flow passage 5 is zero) shown in Figs. 2A and 2B, through a position where the main flow passage 5 is intermediately opened shown in Figs. 4A and 4B, to a position where the opening of the main flow passage 5 is 100% shown in Figs. 5A and 5B. When the main valve 71 is in 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. Together with the main valve 71, 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.

The sub-valve 72 is a belt-like shape curved to fit the inner shape of the valve housing 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. In other words, the position of the sub-valve 72 relative to the main valve 71 remains unchanged regardless of the position of the main valve 71.

By axial rotation of the shaft portion 73, the sub-valve 72 rotates from a position away from the supply port 53 shown in Figures 2A and 2B (i.e., a position where the opening of the supply port 53 is 100%), through a position where the opening is intermediate and part of the supply port 53 is blocked as shown in Figures 4A and 4B, to a position where the supply port 53 is completely blocked as shown in Figures 5A and 5B (i.e., a position where the opening of the supply port 53 is zero).

In this way, the valve mechanism 7 can be switched between the EGR mode shown in Figures 2A and 2B, the non-EGR mode shown in Figures 5A and 5B, and any valve opening shown in Figures 4A and 4B, which is an intermediate state between these two modes.

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

In addition, 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. The sub-valve 72 is also located outside the valve housing portion 54 (specifically, upstream of the valve housing portion 54).

In the intermediate state, a portion of the exhaust gas G is supplied to the EGR passage 6 via the heat exchanger 4, and the remaining exhaust gas G is discharged from the main exhaust port 52. The ratio of the amount of exhaust gas G supplied to the EGR passage 6 to the amount of exhaust gas G discharged from the main exhaust port 52 is determined by the opening degree of the main valve 71 and the sub-valve 72.

The shaft portion 73 is a rod-shaped member (i.e., a stem) connected to the actuator 8. The shaft portion 73 is rotatably attached to the valve housing portion 54. The shaft portion 73 rotates by being driven by the actuator 8. The axial direction of the shaft portion 73 is perpendicular 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. In other words, the sub-valve 72 is attached to the shaft portion 73 so as to move in the circumferential direction of the shaft portion 73. In addition, the supply port 53 is provided on the radial outside of the shaft portion 73.

<Actuator>
The actuator 8 operates the valve mechanism 7. Specifically, the actuator 8 rotates the shaft portion 73 about its axis to displace the valve mechanism 7.

The actuator 8 can be a motor driven by electricity, air pressure, hydraulic pressure, or other power, or a thermoactuator using a thermal expansion body that expands and contracts in response to the temperature of the cooling water.

[1-2. Effects]
According to the embodiment described above in detail, the following effects can be 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 valve structure can be simplified.

(1b) The sub-valve 72 rotates together with the main valve 71, allowing the main valve 71 and the sub-valve 72 to be controlled simultaneously, which facilitates simplification of the valve configuration.

(1c) By arranging the heat exchange section 4 so as to surround at least a portion of the main flow path 5 from the radially outer side, 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 made smaller.

(1d) By facing the shaft portion 73 in the radial direction of the shaft portion 73, 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 exhaust gas G can be increased.

(1e) The absence of any obstructing valves in the EGR flow passage 6 increases the maximum amount of exhaust gas G that can circulate.

2. Other embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(2a) In the exhaust heat recovery device of the above embodiment, the heat exchange unit does not necessarily have to surround at least a portion of the main flow path from the radial outside. For example, as shown in FIG. 6A, the heat exchange unit 4 may be disposed away from the main flow path 5 and connected to the supply port 53 by an auxiliary flow path 9. Furthermore, as shown in FIG. 6B, the heat exchange unit 4 may be disposed adjacent to the side of 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 portion in the radial direction of the shaft portion. For example, as shown in Figures 7A and 7B, the sub-valve 72 may be configured to move within a plane perpendicular to the axial direction of the shaft portion 73. In this case, the supply port 53 to the heat exchange section 4 is provided on a side surface of the main flow path 5 that intersects with the axis of the shaft portion 73. The sub-valve 72 moves along the side surface on which the supply port 53 is provided.

In the EGR mode shown in Figures 7A and 7B, the sub-valve 72 is in a position where it does not overlap the supply port 53, and the main valve 71 is in a position where it completely blocks the main flow passage 5. In the intermediate state shown in Figures 7C and 7D, the sub-valve 72 overlaps part of the supply port 53, and the main valve 71 is in a position where it throttles the flow rate of the main flow passage 5. In the non-EGR mode shown in Figures 7E and 7F, the sub-valve 72 overlaps the entire supply port 53, and the main valve 71 opens the main flow passage 5 to 100%.

(2c) In the exhaust heat recovery device of the above embodiment, the sub-valve does not necessarily have to rotate together 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 times.

(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 among multiple components, or the functions of multiple components may be integrated into one component. In addition, part of the configuration of the above embodiments may be omitted. In addition, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical ideas identified from the wording of the claims are embodiments of the present disclosure.

1... exhaust heat recovery device, 2... catalyst case, 3... catalyst, 4... heat exchange section, 5... main flow path,
6... EGR flow path, 7... valve mechanism, 8... actuator, 9... auxiliary flow path,
41: first water passage port; 42: second water passage port; 43: heat transfer member; 51: inlet port;
52: main exhaust port, 53: supply port, 54: valve housing portion, 71: main valve,
72...sub-valve, 73...shaft portion, 101...internal combustion engine, 102...catalyst device,
103...catalyst device, 104...sub-muffler, 105...main muffler.

Claims (4)

a heat exchange unit that exchanges heat between exhaust gas from the internal combustion engine and cooling water;
a main flow path including an inlet for introducing the exhaust gas, a main exhaust port for exhausting the exhaust gas to the outside, a valve accommodating portion having an inner circumferential surface constituting a part of a sphere, and a supply port disposed on the inner circumferential surface for supplying the exhaust gas to the heat exchange portion;
a valve mechanism disposed inside the valve housing portion and configured to adjust a supply amount of the exhaust gas from the main passage to the heat exchange portion;
Equipped with
the heat exchange unit has an annular shape that surrounds at least a portion of the main flow passage from the radially outer side, and is disposed such that a central axis of the annular shape coincides with a central axis of the main flow passage;
the valve housing portion is located downstream in a flow direction of the exhaust gas from a portion of the main flow passage surrounded by the heat exchange portion,
The valve mechanism includes:
a main valve configured to regulate the flow of the exhaust gas to the main outlet;
a sub-valve having a moving surface along the inner circumferential surface and configured to adjust an opening degree of the supply port by rotating the moving surface along the inner circumferential surface ;
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 having 2. The exhaust heat recovery device according to claim 1,
The sub-valve rotates integrally with the main valve by means of the shaft portion. The exhaust heat recovery device according to claim 1 or 2 ,
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 3 ,
An EGR flow path through which the exhaust gas that has passed through the heat exchange portion flows,
An exhaust heat recovery device, wherein there is no valve in the EGR flow path.

Images