JP7638753B2 - EGR cooler - Google Patents

Description

The present invention relates to an EGR cooler.

An EGR cooler that cools exhaust gas from automobiles and the like is known from Patent Document 1 and other sources.

JP 2014-152626 A

The EGR cooler is provided with a gas inlet for EGR gas flowing in from the internal combustion engine. The pressure of the EGR gas at the gas inlet is not constant, but pulsations occur that periodically vary depending on the operation of the internal combustion engine.
However, when there are multiple gas inlets, the pulsation periods at the gas inlets may differ due to the difference in the ignition timing of the engine or the difference in the length of the piping connecting the internal combustion engine to the EGR cooler. In this case, the pulsation interference occurs, which averages the pressure difference at each gas inlet, and the maximum pressure obtained at the gas inlet decreases, and the desired EGR gas flow may not be obtained in the EGR cooler. Therefore, there has been a demand for the development of an EGR cooler that suppresses the interference of the pulsation while suppressing the increase in the air flow resistance.

The present invention provides an EGR cooler that suppresses pulsation interference while also preventing an increase in air flow resistance.

An EGR cooler according to one aspect of the present invention includes:
a substantially rectangular flat tube through which exhaust gas flows and which is longer in a second direction than in a first direction in a cross-sectional view;
a casing in which a plurality of the tubes are accommodated while being arranged in the first direction;
a single gas inlet for introducing exhaust gas into said tube;
The gas inlet section includes two gas inlets,
the gas inlet portion is provided with a partition portion that separates a space from each of the gas introduction ports to the tube into two spaces independent of each other,
When viewed from the tube side to the gas inlet portion side in a cross section perpendicular to the extending direction of the tubes, the tube side end of the partition portion extends between the two tubes along the second direction.

According to the present invention, a partition that separates the space from the gas inlet to the tube into two independent spaces is provided so as not to impede the flow of gas, thereby providing an EGR cooler that suppresses pulsation interference and prevents an increase in air flow resistance.

1 is a perspective view of an EGR cooler according to a first embodiment of the present invention; FIG. 2 is an exploded perspective view of the EGR cooler according to the first embodiment. 1 is a cross-sectional view of an EGR cooler according to a first embodiment, viewed from above. 4 is a cross-sectional view taken along line IV-IV in FIG. 3, seen from the gas inlet port. 2 is a cross-sectional view of the gas inlet port according to the first embodiment, seen from above. FIG. FIG. 11 is a cross-sectional view of a gas inlet port according to a second embodiment, as viewed from above.

The following describes an embodiment of the present invention with reference to the drawings. For the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

In addition, in the description of this embodiment, for convenience of explanation, the "left-right direction," "front-rear direction," and "up-down direction" will be mentioned as appropriate. Here, the "up-down direction" includes the "upward direction" and the "downward direction." The "front-rear direction" includes the "forward direction" and the "rearward direction." The "left-right direction" includes the "leftward direction" and the "rightward direction." In the figures described below, the symbol U indicates the upward direction. The symbol D indicates the downward direction. The symbol F indicates the forward direction. The symbol B indicates the rearward direction. The symbol L indicates the leftward direction. The symbol R indicates the rightward direction. Note that when the EGR cooler is installed on a vehicle, these directions do not necessarily match the respective directions set for the vehicle.

First Embodiment
Fig. 1 is a perspective view of an EGR cooler 1 according to a first embodiment of the present invention. As shown in Fig. 1, the EGR cooler 1 has a heat exchanger 10, a gas inlet 20 for introducing exhaust gas into the heat exchanger 10, a gas outlet 30 for discharging exhaust gas from the heat exchanger 10, a water inlet 40 for introducing cooling water into the heat exchanger 10, and a water outlet 50 (see Fig. 2) for discharging cooling water from the heat exchanger 10.

In the example shown in FIG. 1, hot exhaust gas flows into the heat exchange section 10 from the front through the gas inlet 20, exchanges heat with the cooling water inside the heat exchange section 10, and the cooled exhaust gas is discharged rearward from the heat exchange section 10 through the gas outlet 30. Cold cooling water flows into the heat exchange section 10 from below through the water inlet 40 at the rear of the heat exchange section 10, exchanges heat with the exhaust gas inside the heat exchange section 10, and the heated cooling water is discharged downward through the water outlet 50 at the front of the heat exchange section 10. The illustrated EGR cooler 1 is a so-called counterflow type EGR cooler in which the cooling water flows in the opposite direction to the exhaust gas flow in the heat exchange section 10.

Fig. 2 is an exploded perspective view of the EGR cooler 1. Fig. 3 is a cross-sectional view of the EGR cooler 1 as viewed from above. As shown in Fig. 2, the heat exchanger 10 has a plurality of tubes 11 and a casing 12 that houses these tubes 11.
The tube 11 is a hollow member through which the exhaust gas flows. The tube 11 has a generally flat rectangular shape that is longer in a second direction than in a first direction in a cross-sectional view. In the illustrated example, the first direction is the left-right direction, and the second direction is the up-down direction.
The casing 12 accommodates a plurality of tubes 11 arranged in a first direction. The number of tubes 11 accommodated in the casing 12 may be any number, but in this embodiment, eleven tubes 11 are provided.
Exhaust gas flows inside the tubes 11. Cooling water flows through the spaces between the tubes 11 inside the casing 12. Fins 17 are provided inside the tubes 11 to aid in heat exchange between the exhaust gas and the cooling water. Dimples 13 are provided on the outer surface of the tubes 11 to induce turbulence in the cooling water and promote heat exchange.

The casing 12 is a rectangular cylindrical member that is long in the front-to-rear direction. A front end plate 14 is attached to the opening at the front end of the casing 12. A rear end plate 15 is attached to the opening at the rear end of the casing 12. The gas inlet section 20 is attached to the casing 12 via the front end plate 14. The gas outlet section 30 is attached to the casing 12 via the rear end plate 15. The tubes 11 are attached to these front end plate 14 and rear end plate 15.

Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. Fig. 5 is a cross-sectional view of gas inlet portion 20 as viewed from above. As shown in Figs. 4 and 5, openings 14a are provided in front end plate 14 at a plurality of positions corresponding to tubes 11. Tubes 11 are fitted into openings 14a of front end plate 14. Exhaust gas introduced into gas inlet portion 20 flows into tubes 11 fitted into openings 14a.
The rear end plate 15 has openings at a plurality of positions corresponding to the tubes 11. The tubes 11 are fitted into the openings of the rear end plate 15. Exhaust gas that has passed through the tubes 11 flows to a gas outlet portion via the openings of the rear end plate 15. The spaces between the openings 14a of the front end plate 14 and the spaces between the openings of the rear end plate 15 are closed, and sealed spaces are formed between the casing 12, the tubes 11, the front end plate 14, and the rear end plate 15. Cooling water flows through these sealed spaces.

The gas inlet section 20 has two gas inlets 21a and 21b and a partition section 22. The gas inlets 21a and 21b are directly or indirectly connected to a pipe connecting the internal combustion engine to the EGR cooler 1, and take in the exhaust gas heated by the internal combustion engine and discharged into the gas inlet section 20. The partition section 22 extends from between the two gas inlets 21a and 21b toward the tube. In other words, the partition section 22 separates the space from the gas inlets 21a and 21b to the tube 11 into two independent spaces on the left and right. In the following description, the space located on the left may be referred to as the left gas passage, and the space located on the right may be referred to as the right gas passage. The partition section 22 is provided to divide the left gas passage and the right gas passage into approximately half and half.

The end of the partition 22 on the tube 11 side has an opposing portion 22a (corresponding to a first portion) extending along the flattened direction of the tube 11 (the vertical direction in this embodiment), and a bridge portion 22b (corresponding to a second portion) extending so as to intersect with the vertical direction. Furthermore, the opposing portion 22a has a first opposing portion 22aA and a second opposing portion 22aB. When viewed from the front, the first opposing portion 22aA is provided between the adjacent tubes 11. The second opposing portion 22aB is also provided between the adjacent tubes 11, and the second opposing portion 22aB is disposed with one tube 11 between it and the first opposing portion 22aA.
When an even number of tubes 11 are provided, the bridge portion 22b is not necessarily provided. However, when an odd number of tubes 11 are provided, the bridge portion 22b arranged to cross the tubes 11 is required to divide the space in the gas inlet portion 20 into a left gas passage and a right gas passage approximately in half.

Here, if the length of the first opposing portion 22aA is l _1a , the length of the second opposing portion 22aB is l _1b , and the length of the bridge portion 22b is l ₂ , the following formula is satisfied.
l ₂ /(l _1a + l _1b )≦1/3

In addition, in the gas inlet portion 20 in this embodiment, a gap S is provided between the partition portion 22 and the tube 11. At this time, the gap S is provided so that the dimension of the gap S is 2 mm or less.

Next, the flow of exhaust gas in the gas inlet 20 will be described with reference to Figures 4 and 5. In Figure 5, exhaust gas flows from the front to the rear. Since a partition 22 is provided to separate the gas inlet 20 into a left gas passage and a right gas passage, the exhaust gases introduced from the gas inlets 21a and 21b reach the tubes 11 without mixing with each other. Most of the exhaust gas that reaches the tubes 11 tries to flow into the tube 11 that is closest among the multiple tubes 11, so even near the tube 11, the exhaust gases introduced through the two gas inlets 21a and 21b flow into the tube 11 with almost no mixing.

The opposing portion 22a of the partition 22 extends in the vertical direction, which is the direction in which the tubes 11 are flattened, and is located between adjacent tubes 11. The opposing portion 22a is positioned so as not to block the tubes 11, so that the flow of exhaust gas into the tubes 11 is not easily impeded by the opposing portion 22a.

In the EGR cooler according to this embodiment, the gas inlet 20 is provided with a partition 22 that separates the space from each gas inlet 21a, 21b to the tube 11 into two independent spaces, the left gas passage and the right gas passage, so that the exhaust gases flowing through the left gas passage and the right gas passage flow into the tube 11 without mixing with each other. In addition, the end of the partition 22 on the tube 11 side extends between the two tubes 11 along the up-down direction, which is the direction in which the tubes 11 are flattened, so that the partition 22 does not easily prevent the exhaust gas from flowing into the tube 11. This provides an EGR cooler 1 that suppresses pulsation interference and prevents an increase in air flow resistance.

In the EGR cooler 1 according to this embodiment, an odd number of tubes 11 are provided, and the end of the partition 22 on the tube 11 side has an opposing portion 22a, which is a first portion extending between the two tubes 11 along the second direction, i.e., the vertical direction, and a crossing portion 22b, which is a second portion extending in a direction intersecting the vertical direction. The length of the crossing portion 22b is 1/3 or less of the length of the opposing portion 22a, so that the crossing portion 22b, which extends to block the tube 11 and may obstruct the flow of exhaust gas into the tube 11, is shorter than the opposing portion 22a. As a result, even when an odd number of tubes 11 are provided, the increase in air flow resistance can be suppressed to a necessary minimum.

In the EGR cooler 1 according to this embodiment, when viewed from above the EGR cooler 1 in a direction perpendicular to the direction in which the tubes 11 extend, a gap S exists between the tube 11 and the end of the partition 22 on the tube 11 side. Because the exhaust gas passing through the gas inlet 20 and the tube 11 is hot, the gas inlet 20 and the tube 11 may expand due to the heat. At this time, because the gap S is provided between the partition 22 and the tube 11, it is possible to reduce the contact and interference between the gas inlet 20 and the tube 11 when the gas inlet 20 and the tube 11 expand.

In the EGR cooler 1 according to this embodiment, the gap S between the gas inlet 20 and the tube 11 is 2 mm or less, and the gap S is provided to take into account the expansion of the gas inlet 20 and the tube 11. In this case, the exhaust gases introduced from the two gas inlets 21a and 21b are further prevented from mixing with each other through the gap S, so that the interference of pulsation can be further reduced.

Next, the EGR cooler according to the second embodiment will be described. Note that the same reference numbers are used for components that are substantially the same as those already described in the first embodiment, and repeated descriptions will be omitted.

6 is a cross-sectional view of the gas inlet part 20A according to the second embodiment as viewed from above. The gas inlet part 20A according to the second embodiment differs from the gas inlet part 20 according to the first embodiment in that the partition part 22A is joined to the tube 11 and the gap S that exists in the gas inlet part 20 according to the first embodiment does not exist in the second embodiment.
In this embodiment, the partition portion 22A and the tube 11 penetrating the front end plate 14 are joined together, but the partition portion may be joined to the front end plate.

In the EGR cooler according to this embodiment, the partition 22A is joined to the tube 11, so that the mixing of the exhaust gas flowing through the left gas passage and the right gas passage near the tube 11 can be further reduced. This makes it possible to further suppress the interference of pulsation.

The present invention has been described above based on the embodiment. This embodiment is an example of the present disclosure, and is not limited to the above-mentioned embodiment, and can be modified, improved, etc. as appropriate. In addition, the material, shape, dimensions, numerical values, form, number, placement location, etc. of each component in the above-mentioned embodiment are arbitrary as long as they can disclose the present invention, and are not limited.

For example, in this embodiment, an EGR cooler in which the water inlet is located behind the water outlet is used as an example, but the EGR cooler may also have a water inlet located ahead of the water outlet, and the cooling water and exhaust gas flow in the same direction.

REFERENCE SIGNS LIST 1 EGR cooler 10 heat exchange section 11 tube 12 casing 13 dimple 14 front end plate 14a opening 15 rear end plate 17 fins 20, 20A gas inlet section 21a, 21b gas introduction port 22, 22A partition section 22a opposing section 22aA first opposing section 22aB second opposing section 22b bridge section 30 gas outlet section 40 water inlet section 50 water outlet section

Claims (4)

a substantially rectangular flat tube through which exhaust gas flows and which is longer in a second direction than in a first direction in a cross-sectional view;
a casing in which a plurality of the tubes are accommodated while being arranged in the first direction;
a single gas inlet for introducing exhaust gas into said tube;
The gas inlet section includes two gas inlets,
the gas inlet portion is provided with a partition portion that separates a space from each of the gas introduction ports to the tube into two spaces independent of each other,
when viewed from the tube side to the gas inlet portion side in a cross section perpendicular to a direction in which the tubes extend, an end portion of the partition portion on the tube side extends between two of the tubes along the second direction ,
There is an odd number of tubes,
an EGR cooler, when viewed from the tube side to the gas inlet side in a cross section perpendicular to the extending direction of the tubes, the tube side end of the partition portion has a first portion extending between the two tubes along the second direction and a second portion extending in a direction intersecting the second direction, and a length of the second portion is 1/3 or less of a length of the first portion . When viewed from a direction perpendicular to the extending direction of the tube, a gap exists between the tube and an end of the partition portion on the tube side.
The EGR cooler of claim 1 . The gap is 2 mm or less.
The EGR cooler according to claim 2 . The casing comprises:
A cylindrical portion having an opening;
an end plate that closes the opening,
the end plate separates a cooling space inside the casing through which cooling water flows and the gas inlet portion through which the exhaust gas flows,
the tube extends through the end plate from the gas inlet to the cooling space,
The partition portion is joined to the tube or the end plate.
The EGR cooler of claim 1 .

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