JP7733596B2 - Valve device - Google Patents

Description

The technology disclosed in this specification relates to a valve device that opens and closes a flow path for high-temperature fluids such as EGR gas.

An example of this type of technology is the "exhaust heat recovery device" described in Patent Document 1 below. This device includes a cooling passage in which a heat exchanger is disposed to exchange heat between exhaust gas emitted from an internal combustion engine and a medium, a bypass passage (bypass passage) through which the exhaust gas bypasses the heat exchanger, and a bypass valve that opens and closes the bypass passage. These components are housed within a cylindrical casing (housing). The heat exchanger is disposed coaxially with and around the bypass passage. The bypass valve includes a valve element that pivots around a valve stem. The valve element is positioned so that it can seat on the outlet of the bypass passage. The valve stem is disposed near the outlet of the bypass passage, midway through the flow path of exhaust gas flowing out from the outlet of the cooling passage. When the bypass valve is closed, exhaust gas flowing in from the upstream side of the device flows through the heat exchanger (cooling passage) around the bypass passage, then flows around the outlet of the bypass passage and out the downstream side of the device. On the other hand, when the bypass valve is open, some of the exhaust gas that flows into the upstream side of the device flows through the bypass passage, while the remaining exhaust gas flows through the cooling passage around the bypass passage. The exhaust gas (cooler gas) flowing out from the outlet of the cooling passage and the exhaust gas (bypass gas) flowing out from the outlet of the bypass passage meet and mix downstream of the device.

WO2006/090725 publication

However, with the device described in Patent Document 1, when the bypass valve opens, the cooler gas flowing out of the cooling passage may interfere with the valve stem or valve element, obstructing its flow, or the heat of the bypass gas may be transferred to the valve element or valve stem, causing the valve stem to overheat. If the flow of cooler gas is obstructed, mixing of the cooler gas and bypass gas may become insufficient, and the temperature of the combined exhaust gas flowing out from the downstream side of the device may not drop to an appropriate level. In this case, if a resin component is installed in the exhaust passage downstream of the device, the resin component may melt. Meanwhile, if the valve stem overheats due to the heat of the bypass gas, thermal damage may occur to components associated with the bypass valve, such as bearings and seals.

This disclosed technology was developed in consideration of the above circumstances, and its first objective is to provide a valve device that can improve the mixing effect between the cooler fluid flowing out of the cooling flow path (heat exchanger) and the bypass fluid flowing out of the bypass flow path when the bypass valve is open. Furthermore, the second objective of this disclosed technology is to provide a valve device that, in addition to achieving the first objective, can also suppress thermal damage to components related to the bypass valve.

In order to achieve the above object, the technology described in claim 1 is a valve device including: a housing in which a flow path for flowing a high-temperature fluid is formed; the flow path includes a cooling flow path having an inlet and an outlet and in which a heat exchanger for cooling the fluid is disposed; a bypass flow path including the inlet and the outlet and bypassing the cooling flow path; and a confluence flow path in which a cooler fluid flowing out from the outlet of the cooling flow path and a bypass fluid flowing out from the outlet of the bypass flow path are converged and flow; a bypass valve is provided for opening and closing the bypass flow path; the bypass valve is located downstream of the cooling flow path and the bypass flow path and includes a valve body that swings around a valve stem, and the valve body is arranged so that it can be seated on the outlet of the bypass flow path as a valve seat; the valve body is supported on the valve stem via a lever; and when the valve body is open, dispersion flow paths are formed between the housing and the lever so that the bypass fluid flowing out from the outlet of the bypass flow path is dispersed and flows toward the outlet of the cooling flow path and the confluence flow path, and the lever is provided with an opening for further dispersing a portion of the bypass fluid dispersed toward the outlet of the cooling flow path toward the valve stem .

According to the configuration of the above technology, when the valve element of the bypass valve is open, a dispersion flow path is formed between the housing and the lever, through which bypass fluid flowing out from the outlet of the bypass flow path is dispersed and flows toward the outlet of the cooling flow path and the merging flow path. Therefore, a portion of the bypass fluid is dispersed by the dispersion flow path and merges with the cooler fluid flowing out from the outlet of the cooling flow path (heat exchanger), and this merged fluid merges in the merging flow path with another portion of the bypass fluid dispersed by the dispersion flow path toward the merging flow path. Furthermore, the lever is provided with an opening for further dispersing a portion of the bypass fluid dispersed toward the outlet of the cooling flow path toward the valve stem. Therefore, the dispersed bypass fluid flows through the opening to the merging flow path, where it merges with the other bypass fluid and the cooler fluid.

In order to achieve the above object, the technology described in claim 2 is the technology described in claim 1 , wherein an insertion hole for inserting the valve stem is formed in the housing, a seal member for sealing between the housing and the valve stem is provided in the insertion hole, and a seal protection means for protecting the seal member from the heat of the bypass fluid is provided at least in a portion of the seal member close to the outlet of the bypass flow path.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 1 , a seal protection means is provided at least in a portion of the seal member that approaches the outlet of the bypass flow path, so that the seal member is protected from the heat of the bypass fluid.

In order to achieve the above object, the technology described in claim 3 is the technology described in claim 2 , wherein the seal protection means includes a first partition against which the bypass fluid collides.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 2 , a first partition against which the bypass fluid collides is provided as seal protection means at least in a portion of the seal member approaching the outlet of the bypass flow path, so that the seal member is protected from the heat of the bypass fluid.

In order to achieve the above object, the technology described in claim 4 is the technology described in claim 2 , wherein the seal protection means includes a configuration that offsets the flow of bypass fluid that is dispersed by the dispersion flow paths toward the merging flow path in a direction away from the seal member.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 2 , the flow of the bypass fluid dispersed by the dispersion flow path toward the merging flow path is offset in a direction away from the seal member, making it more difficult for heat from the bypass fluid to be transmitted to the seal member.

In order to achieve the above object, the technology described in claim 5 is the technology described in any one of claims 1 to 4 , wherein the valve stem is provided with a valve stem protection means for protecting the valve stem from the heat of the bypass fluid dispersed from the opening of the lever.

According to the configuration of the above technology, in addition to the effect of the technology described in any one of claims 1 to 4 , a valve stem protection means is provided on the valve stem, so that the valve stem is protected from the heat of the bypass fluid dispersed from the opening of the lever.

In order to achieve the above object, a sixth aspect of the present invention provides the fifth aspect of the present invention, wherein the valve stem protection means includes a second partition against which the bypass fluid collides.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 5 , a second partition against which the bypass fluid collides is provided on the valve stem as valve stem protection means, so that the valve stem is protected from the heat of the bypass fluid that disperses from the opening of the lever.

In order to achieve the above object, the technology described in claim 7 is the technology described in claim 5 or 6 , in which the valve stem protection means includes a spacer interposed between the valve stem and the lever.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 5 or 6 , a spacer is provided between the valve stem and the lever as a valve stem protection means, so that the contact area between the valve stem and the lever is reduced, and accordingly, heat of the bypass fluid is less likely to be transferred from the lever to the valve stem.

In order to achieve the above object, the technology described in claim 8 is a technology described in any one of claims 1 to 7 , in which a gap is provided at least in a portion between the valve stem and the lever to reduce the contact area between the valve stem and the lever.

According to the configuration of the above technology, in addition to the effect of the technology described in any one of claims 1 to 7 , a gap is provided at least partially between the valve stem and the lever, so that the contact area between the valve stem and the lever is reduced, and accordingly, heat of the bypass fluid is less likely to be transferred from the lever to the valve stem.

In order to achieve the above object, the technology described in claim 9 is the technology described in any one of claims 1 to 8 , wherein a housing corresponding to the converging flow path is provided with a constricted portion that constricts toward the center of the flow of fluid flowing through the converging flow path.

According to the configuration of the above technology, in addition to the effect of the technology described in any one of claims 1 to 8 , a constricted portion is provided in the housing corresponding to the confluent flow path, so that the cooler fluid and bypass fluid flowing through the confluent flow path hit the constricted portion, thereby reducing the flow velocity of these fluids and directing the flow direction toward the center of the confluent flow path.

According to the technology of claim 1, when the bypass valve is opened , it is possible to enhance the mixing effect between the cooler fluid flowing out from the outlet of the cooling flow passage (heat exchanger) and the bypass fluid flowing out from the bypass flow passage.

According to the technology of claim 2 , in addition to the effect of the technology of claim 1 , it is possible to suppress thermal damage to the seal member, which is a member related to the bypass valve, caused by the heat of the bypass fluid.

According to the technology described in claim 3 , it is possible to obtain the same effect as the technology described in claim 2 .

According to the technique described in claim 4 , it is possible to obtain the same effect as the technique described in claim 2 .

According to the technology described in claim 5 , in addition to the effect of the technology described in any one of claims 1 to 4 , it is possible to prevent the heat of the bypass fluid from being directly transmitted to the valve stem, and to suppress thermal damage to the sealing member due to heat transmitted from the valve stem.

According to the technology described in claim 6 , it is possible to obtain the same effect as the technology described in claim 5 .

According to the technology described in claim 7 , in addition to the effect of the technology described in claim 5 or 6 , it is possible to reduce the heat of the bypass fluid transmitted from the lever to the valve stem, and further suppress thermal damage to the sealing member caused by the heat transmitted from the valve stem.

According to the technology described in claim 8 , in addition to the effect of the technology described in any one of claims 1 to 7 , it is possible to reduce the heat of the bypass fluid transmitted from the lever to the valve stem, and further suppress thermal damage to the sealing member caused by the heat transmitted from the valve stem.

According to the technology of claim 9 , in addition to the effect of the technology of any one of claims 1 to 8 , it is possible to further enhance the mixing effect of the cooler fluid and the bypass fluid.

FIG. 2 is a cross-sectional view showing the EGR cooler bypass device according to the first embodiment. 2 is a cross-sectional view showing a portion (downstream side) of the EGR cooler bypass device 1 of FIG. 1 according to the first embodiment. 2 is an enlarged cross-sectional view of the EGR cooler bypass device of FIG. 1 according to the first embodiment, showing a portion surrounded by a dashed-dotted rectangle; FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 showing a part of the EGR cooler bypass device according to the first embodiment. 2 is a perspective view showing a part (downstream side) of the EGR cooler bypass device in a cutaway view according to the first embodiment; FIG. FIG. 6 is an enlarged perspective view of a portion of the broken portion shown in FIG. 5 according to the first embodiment. FIG. 4 is a cross-sectional view equivalent to FIG. 3 showing a flow of bypass gas in the first embodiment. FIG. 3 is a cross-sectional view equivalent to FIG. 2 showing the results of temperature analysis of bypass gas and cooler gas when the bypass valve is open in the first embodiment. FIG. 10 is a cross-sectional view showing the results of temperature analysis of bypass gas and cooler gas at an outlet of the housing in the first embodiment. FIG. 6 is a cross-sectional view equivalent to FIG. 2 showing a part of an EGR cooler bypass device according to a second embodiment. FIG. 5 is an enlarged cross-sectional view equivalent to FIG. 3 showing a part of the EGR cooler bypass device according to the second embodiment. FIG. 11 is a cross-sectional view taken along line BB in FIG. 10 showing a part of the EGR cooler bypass device according to the second embodiment. FIG. 7 is a perspective view equivalent to FIG. 6 showing a part of an EGR cooler bypass device according to a second embodiment. FIG. 12 is a cross-sectional view equivalent to FIG. 11 showing the flow of bypass gas in the second embodiment. FIG. 10 is a cross-sectional view showing a state in which the lever is attached to the valve stem, taken along the axial direction of the valve stem, in the second embodiment. 16 is a view showing the attachment state of the lever to the valve stem as viewed from the tip side of the valve stem (the direction of the arrow X1 in FIG. 15 ) in the second embodiment. FIG. FIG. 10 is a cross-sectional view equivalent to FIG. 8 showing the results of temperature analysis of bypass gas and cooler gas when the bypass valve is open in the second embodiment. FIG. 18 is a cross-sectional view taken along line CC in FIG. 17 showing the results of temperature analysis of bypass gas and cooler gas in the second embodiment. FIG. 10 is a cross-sectional view equivalent to FIG. 9 showing the results of temperature analysis of bypass gas and cooler gas in the second embodiment. FIG. 10 is a cross-sectional view equivalent to FIG. 8 showing the results of temperature analysis of bypass gas and cooler gas when the bypass valve is open, according to a modification of the second embodiment. FIG. 10 is a cross-sectional view equivalent to FIG. 9 showing the results of temperature analysis of bypass gas and cooler gas at the outlet of the housing according to a modified example of the second embodiment. FIG. 10 is a cross-sectional view equivalent to FIG. 2 showing a part of an EGR cooler bypass device according to a third embodiment. FIG. 10 is an enlarged cross-sectional view equivalent to FIG. 3 showing a part of the EGR cooler bypass device according to a third embodiment. FIG. 23 is a cross-sectional view taken along line DD in FIG. 22 showing a part of the EGR cooler bypass device according to the third embodiment. FIG. 10 is a perspective view equivalent to FIG. 6 showing a part of an EGR cooler bypass device according to a third embodiment. FIG. 24 is a cross-sectional view according to the third embodiment, showing the flow of bypass gas, according to the third embodiment, which is equivalent to FIG. 23 . FIG. 10 is a cross-sectional view equivalent to FIG. 8 showing the results of temperature analysis of bypass gas and cooler gas when the bypass valve is open in the third embodiment. FIG. 19 is a cross-sectional view equivalent to FIG. 18 showing the results of temperature analysis of bypass gas and cooler gas in the third embodiment. FIG. 20 is a cross-sectional view equivalent to FIG. 19 showing the results of temperature analysis of bypass gas and cooler gas in the third embodiment. FIG. 10 is a cross-sectional view equivalent to FIG. 8 showing the results of temperature analysis of bypass gas and cooler gas when the bypass valve is open according to a first modification of the fourth embodiment. FIG. 19 is a cross-sectional view equivalent to FIG. 18 showing the results of temperature analysis of bypass gas and cooler gas according to a first modification of the fourth embodiment. FIG. 20 is a cross-sectional view equivalent to FIG. 19 showing the results of temperature analysis of bypass gas and cooler gas according to a first modification of the fourth embodiment. FIG. 31 is a cross-sectional view equivalent to FIG. 30 showing the results of temperature analysis of the bypass gas and the cooler gas when the bypass valve is open according to a second modification of the fourth embodiment. FIG. 32 is a cross-sectional view equivalent to FIG. 31 showing the results of temperature analysis of bypass gas and cooler gas according to a second modification of the fourth embodiment. FIG. 33 is a cross-sectional view equivalent to FIG. 32 showing the results of temperature analysis of bypass gas and cooler gas according to a second modification of the fourth embodiment. FIG. 16 is a cross-sectional view equivalent to FIG. 15 showing a state in which the lever is attached to the valve stem according to another embodiment. FIG. 16 is a cross-sectional view equivalent to FIG. 15 showing a state in which the lever is attached to the valve stem according to another embodiment. FIG. 10 is a cross-sectional view showing the attachment state of the lever to the valve stem, taken along a direction perpendicular to the valve stem, according to another embodiment.

Below, we will explain several embodiments in which the valve device is embodied in an EGR cooler bypass device.

First Embodiment
First, a first embodiment will be described in detail with reference to the drawings. Fig. 1 shows a cross-sectional view of an EGR cooler bypass device 1 according to this embodiment. Fig. 2 shows a cross-sectional view of a portion (downstream side) of the EGR cooler bypass device 1 shown in Fig. 1. Fig. 3 shows an enlarged cross-sectional view of a portion of the EGR cooler bypass device 1 shown in Fig. 1 enclosed by a dashed-dotted rectangle S1. Fig. 4 shows a cross-sectional view of a portion of the EGR cooler bypass device 1 taken along line A-A in Fig. 2. Fig. 5 shows a cutaway perspective view of a portion (downstream side) of the EGR cooler bypass device 1. Fig. 6 shows an enlarged perspective view of a portion of the cutaway portion shown in Fig. 5.

[Outline of EGR cooler bypass device]
As is well known, this EGR cooler bypass device 1 is a device provided in an EGR passage (not shown) that flows a portion of exhaust gas discharged from an engine into an exhaust passage as EGR gas into an intake passage. The device is configured to divide the EGR gas in the EGR passage into a flow that is cooled in an EGR cooler (heat exchanger) and a flow that bypasses the EGR cooler. As shown in FIGS. 1 to 3 , this device 1 includes a housing 4 in which two flow paths 2, 3 are formed for flowing EGR gas, which is a high-temperature fluid. One of the two flow paths 2, 3 is a cooling flow path 2 that includes an inlet 2a and an outlet 2b and in which a heat exchanger 5 for cooling the EGR gas is disposed. The other is a bypass flow path 3 that includes an inlet 3a and an outlet 3b and bypasses the cooling flow path 2. The heat exchanger 5 is configured to cool the EGR gas flowing through the cooling flow path 2, for example, by circulating engine cooling water therethrough. A detailed description thereof will be omitted here.

As shown in Figures 1 to 3, the housing 4 is provided with an inlet 6 for introducing EGR gas into the housing 4 upstream (on the right side in Figure 1) of the inlets 2a, 3a of both flow paths 2, 3, and an outlet 7 for discharging EGR gas from the housing 4 downstream (on the left side in Figure 1) of the outlets 2b, 3b of both flow paths 2, 3. The housing 4 also has a confluence passage 8 between the outlets 2b, 3b of both flow paths 2, 3 and the outlet 7, through which cooler gas flowing out from the outlet 2b of the cooling flow path 2 and bypass gas flowing out from the outlet 3b of the bypass flow path 3 converge and flow. The cooler gas corresponds to an example of a cooler fluid in the disclosed technology, and the bypass gas corresponds to an example of a bypass fluid in the disclosed technology.

As shown in Figures 1 to 4, a bypass valve 10 for opening and closing the bypass flow path 3 is provided in the housing 4 downstream of the outlets 2b, 3b of the flow paths 2, 3. This bypass valve 10 includes a valve element 12 that pivots about a valve stem 11, and the valve element 12 is arranged so that it can seat on the outlet 3b of the bypass flow path 3 as a valve seat. The housing 4 also includes a bearing 13 for rotatably supporting the valve stem 11 and a bearing case 14 for holding the bearing 13. The bearing case 14 is integral with the housing 4 to form the housing 4 and includes a cylindrical portion 14a into which the bearing 13 is press-fitted to hold it, and a flange portion 14b formed at one end of the cylindrical portion 14a. In this embodiment, the bearing 13 can be, for example, a ball bearing. A lip seal 15 is disposed adjacent to the bearing 13 between the cylindrical portion 14a and the valve stem 11. Like the bearing 13, the lip seal 15 is press-fitted into the cylindrical portion 14a. That is, in this embodiment, an insertion hole 14aa is formed in the cylindrical portion 14a of the bearing case 14 that constitutes the housing 4. A lip seal 15 is provided in the insertion hole 14aa to seal between the bearing case 14 (housing 4) and the valve shaft 11. The lip seal 15 corresponds to an example of a sealing member of this disclosed technology.

As shown in Figures 2 to 6, in this embodiment, the valve element 12 is supported on the valve stem 11 via a lever 16. The lever 16 extends in a direction perpendicular to the valve stem 11, with its base end fixed to the valve stem 11 via a rivet 17, and the valve element 12 fixed to its tip end via a rivet 18. As shown in Figure 1, a diaphragm-type actuator 19 for rotating the valve stem 11 is provided on the outside of the housing 4. As shown in Figure 4, the base end (left end in Figure 4) of the valve stem 11 protrudes outward beyond the flange portion 14b of the bearing case 14, and a lever 20 connected to the actuator 19 via a link is fixed to that end. Therefore, from the open state shown in Figures 1 to 6, the valve stem 11 is rotated counterclockwise by the actuator 19, and the valve element 12 swings counterclockwise around the valve stem 11, causing the valve element 12 to seat on the outlet 3b of the bypass flow path 3 and close the valve.

[Configuration for mixing bypass gas and cooler gas]
Fig. 7 shows the flow of bypass gas in a cross-sectional view similar to Fig. 3. As shown in Fig. 7, when the valve element 12 is open, dispersion channels 21 and 22 are formed between the housing 4, the lever 16, and the valve element 12, through which the bypass gas flowing out from the outlet 3b of the bypass channel 3 is dispersed and flows toward the outlet 2b of the cooling channel 2 and the merging channel 8. That is, in the first dispersion channel 21, as shown by a thick dashed line in Fig. 7, a portion of the bypass gas flows toward the outlet 2b of the cooling channel 2, and in the second dispersion channel 22, as shown by a thick dashed line in Fig. 7, a portion of the bypass gas flows toward the merging channel 8. Note that the actuator 19 is not shown in Figs. 2 to 7.

In addition, as shown in Figures 2 to 7, the lever 16 is provided with an opening 16a for further dispersing, toward the valve stem 11, a portion of the bypass gas that is dispersed in the first dispersion flow path 21 toward the outlet 2b of the cooling flow path 2. As shown by the thick dashed dotted line in Figure 7, a portion of the bypass gas flowing through the first dispersion flow path 21 flows into this opening 16a and is dispersed toward the valve stem 11.

[Seal protection measures]
Here, the high-temperature bypass gas flowing from the outlet 3b of the bypass flow path 3 through the second dispersion flow path 22 toward the merging flow path 8 flows near the lip seal 15. Therefore, in this embodiment, as shown in FIGS. 2 to 6 , a seal protection means is provided in at least a portion of the lip seal 15 close to the outlet 3b of the bypass flow path 3 to protect the lip seal 15 from the heat of the bypass gas. In this embodiment, the seal protection means includes a first partition 16b against which the bypass gas collides, protecting the lip seal 15 from the bypass gas. The first partition 16b is formed integrally with the lever 16 by folding back a portion of the lever 16 at a right angle.

In addition, this embodiment includes a seal protection mechanism that offsets the flow of bypass gas dispersed by the second dispersion flow path 22 toward the merging flow path 8 in a direction away from the lip seal 15. That is, in this embodiment, as shown in FIG. 4, the position P1 of the outlet 3b of the bypass flow path 3 and the center of the valve element 12 is offset from the central axis P0 of the bypass flow path 3 in a direction away from the lip seal 15.

[Valve stem protection means]
Here, the high-temperature bypass gas dispersing from the opening 16a of the lever 16 flows toward the valve stem 11. Therefore, in this embodiment, as shown in FIGS. 2 to 6 , the valve stem 11 is provided with a valve stem protection means for protecting the valve stem 11 from the heat of the high-temperature bypass gas dispersing from the opening 16a of the lever 16. In this embodiment, the valve stem protection means includes a second partition 24a against which the bypass gas collides and a spacer 24b interposed between the valve stem 11 and the lever 16. The second partition 24a and the spacer 24b are integrally formed by a bent plate 24 bent at a substantially right angle. In this embodiment, as shown in FIG. 3 , the length L1 of the second partition 24a is longer than the radial length L2 of the valve stem 11. Furthermore, as shown in FIG. 4 , the width W1 of the second partition 24a is greater than the width W2 of the opening 16a.

[Operation and Effects of the EGR Cooler Bypass Device]
According to the configuration of the EGR cooler bypass device of this embodiment described above, when the valve body 12 of the bypass valve 10 is opened, dispersion passages 21, 22 are formed between the housing 4 and the lever 16, through which bypass gas flowing out from the outlet 3b of the bypass passage 3 is dispersed and flows toward the outlet 2b of the cooling passage 2 (heat exchanger 5) and the junction passage 8. Therefore, a portion of the bypass gas is dispersed by the first dispersion passage 21 and merges with the cooler gas flowing out from the outlet 2b of the cooling passage 2 (heat exchanger 5), and the merged cooler gas and bypass gas are merged in the junction passage 8 with another portion of the bypass gas dispersed toward the junction passage 8 by the second dispersion passage 22. Therefore, when the bypass valve 10 is opened, the mixing effect of the cooler gas flowing out from the outlet 2b of the cooling passage 2 (heat exchanger 5) and the bypass gas flowing out of the bypass passage 3 can be improved.

In this embodiment, the lever 16 is provided with an opening 16a for further dispersing a portion of the bypass gas dispersed toward the outlet 2b of the cooling channel 2 toward the valve stem 11. Therefore, the bypass gas dispersed through the opening 16a flows into the confluence channel 8, where it merges with other bypass gas and cooler gas. In other words, in this embodiment, the bypass gas dispersed into the first dispersion channel 21 is further dispersed by the opening 16a of the lever 16, thereby diffusing the bypass gas toward the confluence channel 8. This further enhances the mixing effect between the cooler gas and the bypass gas.

In this embodiment, a portion of the bypass gas that disperses through the first dispersion flow path 21 toward the outlet 2b of the cooling flow path 2 is dispersed toward the valve stem 11 through the opening 16a. This reduces the inflow of bypass gas into the lip seal 15 and the outer periphery of the bearing case 14. This reduces thermal damage to the lip seal 15 and the valve stem 11 caused by the heat of the bypass gas. Furthermore, since the inflow of bypass gas into the outer periphery of the lip seal 15 and the bearing case 14 is reduced, cooler gas flows into the outer periphery of the bearing case 14 to the same extent, cooling the bearing case 14 and improving the heat resistance of the lip seal 15.

In this embodiment, the first partition 16b is provided as a seal protection means at least in the portion of the lip seal 15 that is close to the outlet 3b of the bypass flow path 3, protecting the lip seal 15 from the heat of the bypass gas. This prevents thermal damage to the lip seal 15, which is a component associated with the bypass valve 10, caused by the heat of the bypass gas.

According to the configuration of this embodiment, as a further seal protection measure, the position P1 of the outlet 3b of the bypass flow path 3 and the center of the valve element 12 is offset away from the lip seal 15 from the central axis P0 of the bypass flow path 3. Therefore, the flow of bypass gas dispersed toward the merging flow path 8 by the second dispersion flow path 22 is offset away from the lip seal 15, making it more difficult for heat from the bypass gas to be transmitted to the lip seal 15. In this sense, thermal damage to the lip seal 15, which is a component associated with the bypass valve 10, due to the heat of the bypass gas can be suppressed.

In this embodiment, the valve stem 11 is provided with a second partition 24a as a valve stem protection means, protecting the valve stem 11 from the heat of the bypass gas dispersing from the opening 16a of the lever 16. This prevents the heat of the bypass gas from being directly transferred to the valve stem 11, thereby suppressing thermal damage to the lip seal 15 due to heat transferred from the valve stem 11.

In this embodiment, a spacer 24b is provided between the valve stem 11 and the lever 16 as a valve stem protection means, reducing the contact area between the valve stem 11 and the lever 16 and making it more difficult for the heat of the bypass gas to be transferred from the lever 16 to the valve stem 11. This reduces the heat of the bypass gas transferred from the lever 16 to the valve stem 11, further suppressing thermal damage to the lip seal 15 caused by heat transferred from the valve stem 11.

[Bypass gas and cooler gas temperature analysis results]
Here, the results of the temperature analysis of the bypass gas and cooler gas will be explained. Fig. 8 shows the results of the temperature analysis of the bypass gas and cooler gas when the bypass valve 10 is open in a cross-sectional view similar to Fig. 2. Fig. 9 shows the results of the temperature analysis of the bypass gas and cooler gas at the outlet 7 of the housing 4 in a cross-sectional view. In Figs. 8 and 9, the dark areas with the highest dot density indicate a temperature of around 240°C, and the light areas with the lowest dot density indicate a temperature of around 80°C. In Figs. 8 and 9, cross-sectional hatching of components such as the housing 4 has been omitted (the same applies to the cross-sectional views of the other temperature analysis results shown later).

In this embodiment, as shown in Figure 8, the high-temperature bypass gas flowing out from the outlet 3b of the bypass flow path 3 is dispersed into the first dispersion flow path 21 and the second dispersion flow path 22, and a portion of the high-temperature bypass gas flowing through the first dispersion flow path 21 is dispersed from the opening 16a of the lever 16 toward the valve stem 11. It can also be seen that the high-temperature bypass gas dispersed into the first dispersion flow path 21 merges with the cooler gas flowing out from the outlet 2b of the cooling flow path 2, and the temperature of the combined gas decreases. The cooled combined gas merges with the bypass gas flowing out from the opening 16a in the downstream merger flow path 8, and this combined gas merges with the bypass gas dispersed into the second dispersion flow path 22 in the downstream merger flow path 8, and the temperature of the combined gas decreases further. In this embodiment, the gas temperature at the lip seal 15 was 137°C. This is thought to be because the first partition 16b protects the lip seal 15 from the bypass gas, and the second partition 24a and spacer 24b make it difficult for the heat of the bypass gas dispersed from the opening 16a toward the valve stem 11 to be transferred to the valve stem 11. In this embodiment, by dispersing the bypass gas flowing out from the outlet 3b of the bypass flow path 3 into three flows, it is possible to achieve both improved mixing of the bypass gas and cooler gas and protection of the lip seal 15.

As a result of the above mixing, the temperature of the EGR gas flowing out of the outlet 7 of the housing 4 was 183.5°C at position (1), 175.0°C at position (2), 98.3°C at position (3), and 98.8°C at position (4), as shown in Figure 9. The final maximum temperature was 184.1°C, the minimum temperature was 97.3°C, and the average temperature was 152.2°C. In this embodiment, the maximum temperature at the outlet 7 decreased, and the high-temperature gas was dispersed in the center of the outlet 7, resulting in a decrease in gas temperature at the periphery.

Second Embodiment
Next, a second embodiment will be described in detail with reference to the drawings. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals and will not be described again, and differences will be mainly described.

This embodiment differs from the first embodiment in the configuration related to mixing of bypass gas and cooler gas and the configuration of the valve stem protection means. Figure 10 shows a portion of the EGR cooler bypass device 1 in a cross-sectional view equivalent to Figure 2. Figure 11 shows a portion of the EGR cooler bypass device 1 in an enlarged cross-sectional view equivalent to Figure 3. Figure 12 shows a portion of the EGR cooler bypass device 1 in a cross-sectional view taken along line B-B in Figure 10. Figure 13 shows a portion of the EGR cooler bypass device 1 in a perspective view equivalent to Figure 6. Figure 14 shows the flow of bypass gas in a cross-sectional view equivalent to Figure 11.

[Configuration for mixing bypass gas and cooler gas]
As shown in FIGS. 10 to 14, the lever 16 of this embodiment differs from the first embodiment in that it does not have an opening 16a.

[Valve stem protection means]
In this embodiment, the lever 16 is not provided with an opening 16a, so the high-temperature bypass gas that has passed through the lever 16 does not flow toward the valve stem 11. Therefore, in this embodiment, as shown in Figures 10 to 14, the bent plate 24 including the second partition 24a and spacer 24b is not provided as valve stem protection means for protecting the valve stem 11 from the heat of the high-temperature bypass gas. Instead, a different configuration is provided as the valve stem protection means.

That is, Figure 15 shows a cross-sectional view taken along the axial direction of the valve stem 11, illustrating the attachment state of the lever 16 to the valve stem 11. Figure 16 shows the attachment state of the lever 16 to the valve stem 11, viewed from the tip side of the valve stem 11 (the direction of arrow X1 in Figure 15). As shown in Figures 12 and 15, in this embodiment, a gap 26 is provided in a portion between the valve stem 11 and the lever 16 to reduce the contact area between the valve stem 11 and the lever 16. In this embodiment, the lever 16 has a recess 16c on the front side where the head 17a of the rivet 17 contacts, and a protrusion 16d on the opposite back side. The gap 26 between the valve stem 11 and the lever 16 is formed when the lever 16 contacts the valve stem 11 at the protrusion 16d.

[Other configurations]
15 and 16, a stopper 16e is provided on the lever 16 at the tip end of the valve stem 11. This stopper 16e is formed by bending a portion of the lever 16 to engage with the end surface of the valve stem 11 to prevent the lever 16 from rotating relative to the valve stem 11. Furthermore, as shown in FIG. 13, the stopper 16e is curved toward the valve stem 11, so that bypass gas that collides with the surface of the lever 16 can easily flow to the side of the lever 16 opposite the first partition 16b. Therefore, the bypass gas that collides with the lever 16 can be guided in a direction away from the lip seal 15.

[Operation and Effects of the EGR Cooler Bypass Device]
According to the configuration of the EGR cooler bypass device 1 of this embodiment described above, the gap 26 is provided at least partially between the valve stem 11 and the lever 16, thereby reducing the contact area between the valve stem 11 and the lever 16 and making it more difficult for heat of the bypass gas to be transferred from the lever 16 to the valve stem 11. This reduces the heat of the bypass gas transferred from the lever 16 to the valve stem 11, and further suppresses thermal damage to the lip seal 15 due to heat transferred from the valve stem 11.

[Bypass gas and cooler gas temperature analysis results]
The results of the temperature analysis of the bypass gas and cooler gas will now be described. Figure 17 shows the results of the temperature analysis of the bypass gas and cooler gas when the bypass valve 10 is open in a cross-sectional view equivalent to Figure 8. Figure 18 shows the results of the temperature analysis of the bypass gas and cooler gas in a cross-sectional view taken along line CC in Figure 17. Figure 19 shows the results of the temperature analysis of the bypass gas and cooler gas in a cross-sectional view equivalent to Figure 9.

In this embodiment, as shown in Figures 17 and 18, the high-temperature bypass gas flowing out from the outlet 3b of the bypass flow path 3 is dispersed into two flow paths: the first dispersion flow path 21 and the second dispersion flow path 22. The high-temperature bypass gas dispersed into the first dispersion flow path 21 merges with the cooler gas flowing out from the outlet 2b of the cooling flow path 2, and flows downstream through the merged flow path 8 while decreasing in temperature as the merged gas. The lowered-temperature merged gas flows parallel to the bypass gas dispersed into the second dispersion flow path 22 in the merged flow path 8, and the two gases merge downstream of the merged flow path 8, tending to decrease in temperature as the merged gas. In this embodiment, the gas temperature at the lip seal 15 was 171°C.

As a result of the above-described mixing, the temperature of the EGR gas flowing out of the outlet 7 of the housing 4 decreased slightly in maximum temperature, as shown in Figure 19, but the gas temperature tended to be higher at the upper periphery of the outlet 7 and lower elsewhere. The final maximum temperature was 206°C. This is thought to be because the bypass gas was dispersed into the two dispersion flow paths 21 and 22, slightly increasing its flow velocity and worsening the mixing of the cooler gas and bypass gas.

[Results of temperature analysis of bypass gas and cooler gas for the modified example of the second embodiment]
Here, the results of temperature analysis of the bypass gas and cooler gas in a modified example of the second embodiment will be described. This modified example differs from the second embodiment in that the lever 16 does not have the first partition 16b. Figure 20 shows the results of temperature analysis of the bypass gas and cooler gas when the bypass valve 10 is open, in a cross-sectional view equivalent to Figure 8. Figure 21 shows the results of temperature analysis of the bypass gas and cooler gas at the outlet 7 of the housing 4, in a cross-sectional view equivalent to Figure 9.

As shown in FIG. 20 , in this modified example, similar to the second embodiment, the high-temperature bypass gas flowing out from the outlet 3b of the bypass flow path 3 is dispersed into two paths: the first dispersion path 21 and the second dispersion path 22. The high-temperature bypass gas dispersed into the first dispersion path 21 merges with the cooler gas flowing out from the outlet 2b of the cooling path 2, and flows downstream through the merged path 8 as a merged gas, lowering its temperature. The lowered-temperature merged gas then flows parallel to the bypass gas dispersed into the second dispersion path 22, and the two gases merge downstream of the merged path 8, tending to decrease in temperature as a merged gas.

As a result of the above mixing, the temperature of the EGR gas flowing out of the outlet 7 of the housing 4 was 224.1°C at position (1), 211.1°C at position (2), 126.9°C at position (3), and 125.2°C at position (4), as shown in Figure 21. Ultimately, the maximum temperature was 225.6°C, the minimum temperature was 124.9°C, and the average temperature was 158.2°C. The gas temperature at the lip seal 15 was 201°C. In other words, in this modified example, the maximum temperature was slightly higher than in the second embodiment, and the gas temperature at the lip seal 15 was also slightly higher.

Third Embodiment
Next, a third embodiment will be described in detail with reference to the drawings.

This embodiment differs from the previous embodiments in terms of the configuration related to mixing of bypass gas and cooler gas, and the configuration of the seal protection means and valve stem protection means. Figure 22 shows a portion of the EGR cooler bypass device 1 in a cross-sectional view equivalent to Figure 2. Figure 23 shows a portion of the EGR cooler bypass device 1 in an enlarged cross-sectional view equivalent to Figure 3. Figure 24 shows a portion of the EGR cooler bypass device 1 in a cross-sectional view taken along line D-D in Figure 22. Figure 25 shows a portion of the EGR cooler bypass device 1 in a perspective view equivalent to Figure 6. Figure 26 shows the flow of bypass gas in a cross-sectional view equivalent to Figure 23.

[Configuration for mixing bypass gas and cooler gas]
As shown in FIGS. 22 to 26, in this embodiment, similar to the second embodiment, the lever 16 is not provided with an opening 16a.

[Seal protection measures]
In this embodiment, as in the modified example of the second embodiment, the first partition 16b described in the first embodiment is not provided. Furthermore, in this embodiment, the outlet 3b of the bypass flow path 3 and the valve body 12 are not offset from each other to direct the flow of bypass gas away from the lip seal 15. Instead, in this embodiment, as shown in Figures 24 and 25, protrusions 16f extending along the longitudinal direction are formed on both sides of the front side of the lever 16. These protrusions 16f guide the bypass gas that flows out from the outlet 3b of the bypass flow path 3 and hits the lever 16 to each of the dispersion flow paths 21, 22.

[Valve stem protection means]
In this embodiment, similarly to the second embodiment, the lever 16 is not provided with an opening 16a, and therefore, as shown in Figures 22 to 26, the bent plate 24 including the second partition 16g and the spacer 24b is not provided as a valve stem protection means for protecting the valve stem 11 from the heat of the high-temperature bypass gas.

[Operation and Effects of the EGR Cooler Bypass Device]
According to the configuration of the EGR cooler bypass device 1 of this embodiment described above, similarly to the previous embodiments, when the valve body 12 of the bypass valve 10 is opened, dispersion passages 21, 22 are formed between the housing 4 and the lever 16, through which the bypass gas flowing out from the outlet 3b of the bypass passage 3 is dispersed and flows toward the outlet 2b of the cooling passage 2 (heat exchanger 5) and the junction passage 8. Therefore, a portion of the bypass gas is dispersed by the first dispersion passage 21 and merges with the cooler gas flowing out from the outlet 2b of the cooling passage 2 (heat exchanger 5), and this merged gas merges in the junction passage 8 with another portion of the bypass gas dispersed by the second dispersion passage 22 toward the junction passage 8. Therefore, in this embodiment as well, when the bypass valve 10 is opened, the mixing effect of the cooler gas flowing out from the outlet 2b of the cooling passage 2 (heat exchanger 5) and the bypass gas flowing out of the bypass passage 3 can be improved.

[Bypass gas and cooler gas temperature analysis results]
The results of the temperature analysis of the bypass gas and the cooler gas will now be described. Figure 27 shows the results of the temperature analysis of the bypass gas and the cooler gas when the bypass valve 10 is open, in a cross-sectional view similar to Figure 8. Figure 28 shows the results of the temperature analysis of the bypass gas and the cooler gas, in a cross-sectional view similar to Figure 18. Figure 29 shows the results of the temperature analysis of the bypass gas and the cooler gas, in a cross-sectional view similar to Figure 19.

In this embodiment, as with the modified example of the second embodiment, the lever 16 is not provided with the first partition 16b, and the outlet 3b of the bypass flow path 3 and the valve body 12 are not offset to direct the flow of bypass gas away from the lip seal 15, so the gas temperature at the lip seal 15 is 265°C.

In this embodiment, as shown in Figures 27 and 28, similar to the second embodiment, the high-temperature bypass gas flowing out from the outlet 3b of the bypass flow path 3 is dispersed into two paths, the first dispersion path 21 and the second dispersion path 22. The high-temperature bypass gas dispersed into the first dispersion path 21 merges with the cooler gas flowing out from the outlet 2b of the cooling path 2, and flows downstream through the merged path 8 while its temperature is reduced as the merged gas; however, the degree of merging is slightly lower than in the second embodiment. The cooled merged gas then flows in parallel with the bypass gas dispersed into the second dispersion path 22 in the merged path 8, and the two gases merge downstream of the merged path 8, reducing their temperature as the merged gas.

As a result of the above mixing, the temperature of the EGR gas flowing out of the outlet 7 of the housing 4 decreased slightly in maximum temperature, as shown in Figure 29, but the gas temperature tended to be higher at the upper periphery of the outlet 7 and lower elsewhere. The final maximum temperature was 194°C.

Fourth Embodiment
Next, a fourth embodiment will be described in detail with reference to the drawings.

This embodiment differs from the previous embodiments in terms of the shape of the housing 4 corresponding to the merging flow path 8. Figure 30 shows the results of temperature analysis of the bypass gas and cooler gas when the bypass valve 10 is open, in a cross-sectional view equivalent to Figure 8. Figure 31 shows the results of temperature analysis of the bypass gas and cooler gas, in a cross-sectional view equivalent to Figure 18. Figure 32 shows the results of temperature analysis of the bypass gas and cooler gas, in a cross-sectional view equivalent to Figure 19.

[Configuration of the confluence flow path]
30, in this embodiment, the housing 4 corresponding to the junction passage 8 is provided with a constricted portion 8a that narrows toward the center of the flow of EGR gas flowing through the junction passage 8. The other configurations are the same as those of the above-described embodiments.

[Operation and Effects of the EGR Cooler Bypass Device]
The configuration of the EGR cooler bypass device 1 of this embodiment described above provides the following advantages in addition to the advantages of the previous embodiments. That is, the housing 4 corresponding to the junction passage 8 is provided with a constricted portion 8a, so that the cooler gas and bypass gas flowing through the junction passage 8 hit the constricted portion 8a, reducing the flow velocity of these gases and directing their flow toward the center of the junction passage 8. This further enhances the mixing effect of the cooler gas and the bypass gas. In particular, this improves the mixing of the cooler gas and the bypass gas downstream of the junction passage 8.

In this embodiment, the maximum temperature of the EGR gas at the outlet 7 was 183°C, and the gas temperature at the lip seal 15 was 214°C.

[Regarding the first modified example of the fourth embodiment]
A first modified example of the fourth embodiment will now be described with reference to Fig. 30. In this modified example, as indicated by the two-dot chain line in Fig. 30, the position of the constricted portion 8b is moved downstream of the constricted portion 8a of the fourth embodiment in the merging passage 8. This makes it possible to reduce the pressure loss of the bypass gas flowing into the second dispersion passage 22 more than in the fourth embodiment, thereby improving the mixing of the bypass gas and the cooler gas.

[Regarding the second modified example of the fourth embodiment]
Next, a second modified example of the fourth embodiment will be described with reference to Figures 33 to 35. This modified example differs from the fourth embodiment in the configuration of the bypass valve 10. Figure 33 shows the results of temperature analysis of the bypass gas and cooler gas when the bypass valve 10 is open, in a cross-sectional view equivalent to Figure 30. Figure 34 shows the results of temperature analysis of the bypass gas and cooler gas, in a cross-sectional view equivalent to Figure 31. Figure 35 shows the results of temperature analysis of the bypass gas and cooler gas, in a cross-sectional view equivalent to Figure 32.

As shown in Figure 33, in this embodiment, a third partition 28a is provided on the valve stem 11 to reduce the flow area of the second dispersion flow path 22 when the bypass valve 10 is open. As shown in Figure 33, the third partition 28a is formed integrally with a spacer 28b interposed between the valve stem 11 and the lever 16 and is composed of a bent plate 28 bent at a nearly right angle. This modified configuration improves the mixing effect of the bypass gas and cooler gas downstream of the merging flow path 8. However, since the pressure loss of the bypass gas in the second dispersion flow path 22 increases, the amount of bypass gas flowing near the valve stem 11 increases accordingly, which is disadvantageous in terms of thermal damage to the lip seal 15.

<Another embodiment>
It should be noted that the disclosed technology is not limited to the above-described embodiments, and can be implemented as follows by appropriately modifying part of the configuration within the scope of the disclosed technology.

(1) In the second embodiment, a convex portion 16d was formed on the lever 16, thereby providing a gap 26 between the outer periphery of the valve stem 11 and the lever 16. In contrast, as shown in Figure 36, a concave portion 11a is formed on the outer periphery of the valve stem 11, thereby providing a gap 27 between the valve stem 11 and the lever 16. In this case, the shaft diameter D1 of the portion where the concave portion 11a is formed on the outer periphery of the valve stem 11 is reduced by the amount of the concave portion 11a. This reduces the heat transfer area from the valve stem 11 to the lip seal 15, thereby suppressing thermal damage to the lip seal 15. Figure 36 is a cross-sectional view similar to Figure 15 showing the attachment state of the lever 16 to the valve stem 11.

(2) In another embodiment of (1) above, a recess 11a is formed on the outer periphery of the valve stem 11, thereby providing a gap 27 between the valve stem 11 and the lever 16. In contrast, as shown in Figure 37, the recess 11a can be omitted from the outer periphery of the valve stem 11, thereby eliminating the gap 27 between the valve stem 11 and the lever 16. Figure 37 shows the attachment state of the lever 16 to the valve stem 11 in a cross-sectional view similar to Figure 15.

(3) In the first embodiment, as shown in FIG. 3, a bent plate 24 including a second partition 24a positioned at a position where the bypass gas flowing in from the opening 16a collides and a spacer 24b interposed between the valve stem 11 and the lever 16 is provided as a valve stem protection means. Alternatively, as shown in FIG. 38, instead of omitting the second partition 24a, a second partition 16g can be formed by punching and bending a portion of the lever 16 to form the opening 16a. In this case, the second partition 16g is thicker than the second partition 24a, and therefore the partition 16g is closer to the opening 16a, thereby reducing the flow area CA of the opening 16a. Furthermore, the length and width of the second partition 16g are limited by the size of the opening 16a. In this respect, although the second partition 16g has a smaller collision prevention area for the bypass gas than the second partition 24a, it still functions to protect the valve stem 11. In addition, the second partition 16g can be formed integrally with the lever 16, reducing the number of parts required to construct the bypass valve 10. Furthermore, as shown in Figure 38, instead of omitting the spacer 24b, a recess 16c can be formed on the front side of the lever 16 and a protrusion 16d can be formed on the opposite back side. By contacting the lever 16 with the valve stem 11 at the protrusion 16d, a gap 26 can be created between the lever 16 and the valve stem 11. This reduces the contact area between the lever 16 and the valve stem 11. Figure 38 shows the attachment state of the lever 16 to the valve stem 11 in a cross-sectional view taken perpendicular to the valve stem 11.

(4) In the above embodiment, the cooling flow path 2 and the bypass flow path 3 are formed integrally in the housing 4, but these two flow paths can also be formed separately and merged.

This disclosed technology can be used in engine exhaust passages and EGR passages.

REFERENCE SIGNS LIST 1 EGR cooler bypass device 2 Cooling flow path 2a Inlet 2b Outlet 3 Bypass flow path 3a Inlet 3b Outlet 4 Housing 5 Heat exchanger 8 Merging flow path 8a Narrowed portion 8b Narrowed portion 10 Bypass valve 11 Valve shaft 12 Valve body 13 Bearing 14 Bearing case (housing)
14aa Insertion hole 15 Lip seal (sealing member)
16 Lever 16a Opening 16b First partition (seal protection means)
16g Second partition (valve stem protection means)
21 First branch flow path 22 Second branch flow path 24a Second partition (valve stem protection means)
24b Spacer (valve stem protection means)
26 Gap (valve stem protection means)
27 Gap (Valve stem protection means)

Claims (9)

a housing having a flow path for a high-temperature fluid;
The flow path is
a cooling flow path including an inlet and an outlet, in which a heat exchanger is disposed for cooling the fluid;
a bypass flow path including an inlet and an outlet, the bypass flow path bypassing the cooling flow path;
a confluence flow path in which a cooler fluid flowing out from the outlet of the cooling flow path and a bypass fluid flowing out from the outlet of the bypass flow path are joined together and flow,
a bypass valve for opening and closing the bypass flow path is provided;
the bypass valve is disposed downstream of the cooling flow path and the bypass flow path and includes a valve body that swings around a valve stem,
In the valve device, the valve element is provided so as to be able to seat on the outlet of the bypass flow path as a valve seat,
the valve body is supported on the valve stem via a lever,
When the valve body is opened, a dispersion flow path is formed between the housing and the lever, through which the bypass fluid flowing out from the outlet of the bypass flow path is dispersed and flows toward the outlet of the cooling flow path and the merging flow path ,
The lever is provided with an opening for further dispersing a portion of the bypass fluid that is dispersed toward the outlet of the cooling channel toward the valve stem.
A valve device characterized by: The valve device according to claim 1 ,
an insertion hole for inserting the valve stem is formed in the housing;
a seal member for sealing between the housing and the valve stem is provided in the insertion hole;
10. A valve device according to claim 9, further comprising a seal protection means for protecting said seal member from heat of the bypass fluid, at least at a portion of said seal member that is close to said outlet of said bypass flow passage. 3. The valve device according to claim 2 ,
10. A valve device according to claim 9, wherein the seal protection means includes a first partition against which the bypass fluid collides. 3. The valve device according to claim 2 ,
The valve device according to claim 1, wherein the seal protection means includes a structure for offsetting the flow of the bypass fluid dispersed by the dispersion flow paths toward the merging flow path in a direction away from the seal member. The valve device according to any one of claims 1 to 4 ,
A valve device characterized in that the valve stem is provided with a valve stem protection means for protecting the valve stem from heat of the bypass fluid dissipating from the opening of the lever. The valve device according to claim 5 ,
The valve device according to claim 1, wherein the valve stem protection means includes a second partition against which the bypass fluid collides. 7. The valve device according to claim 5 or 6 ,
The valve device according to claim 1, wherein the valve stem protection means includes a spacer interposed between the valve stem and the lever. The valve device according to any one of claims 1 to 7 ,
A valve device, characterized in that a gap is provided at least partially between the valve stem and the lever to reduce the contact area between the valve stem and the lever. 9. The valve device according to claim 1,
The valve device according to claim 1, wherein the housing corresponding to the merging passage is provided with a constricted portion that is constricted toward a center of the flow of the fluid flowing through the merging passage.