WO2017126126A1

WO2017126126A1 - Valve device for exhaust gas flow passage

Info

Publication number: WO2017126126A1
Application number: PCT/JP2016/051922
Authority: WO
Inventors: 宗弘壷阪; 泰史梅野
Original assignee: フタバ産業株式会社
Priority date: 2016-01-22
Filing date: 2016-01-22
Publication date: 2017-07-27

Abstract

A valve device for an exhaust gas flow passage is provided with a flow passage member, a valve body, and a maintenance mechanism. The flow passage member has therein an exhaust gas flow passage. The valve body is rotationally movable within the exhaust gas flow passage relative to the flow passage member. The maintenance mechanism is provided outside the flow passage member and applies to the valve body an external force for maintaining the valve body at a closed position where the exhaust gas flow passage is fully closed. Specifically, the valve body is provided so as to be rotationally moved from the closed position in the opening direction by the pressure of exhaust gas.

Description

Exhaust flow path valve device

The present disclosure relates to an exhaust passage valve device.

2. Description of the Related Art A configuration in which a valve device that opens and closes a flow path is provided in an exhaust flow path that is a flow path of exhaust gas discharged from an internal combustion engine is known. Patent Document 1 describes a configuration in which a valve device is provided downstream of a catalyst that purifies exhaust gas in an exhaust passage. In the valve device described in Patent Document 1, in a state where the pressure of the exhaust gas is low, the valve body is maintained in a closed position where the exhaust passage is most closed by the force of the spring. When the pressure of the exhaust gas increases, the valve body is pushed by the exhaust gas, and the valve body rotates in the opening direction from the closed position. As described above, the valve device in which the position of the valve body changes in accordance with the pressure of the exhaust gas has an advantage that the configuration is simpler than the configuration in which the position of the valve body is controlled by electric power.

JP 2007-231820 A

In the configuration described in Patent Document 1 described above, high heat resistance is required for a configuration in which an external force for maintaining the valve body in the closed position is applied to the valve body.
In one aspect of the present disclosure, it is desirable to realize a configuration in which an external force for maintaining the valve body in the closed position is applied to the valve body with relatively low heat resistance.

One aspect of the present disclosure is an exhaust flow path valve device that includes a flow path member, a valve body, and a maintenance mechanism. The flow path member has an exhaust flow path inside. The valve body is rotatable with respect to the flow path member in the exhaust flow path. The maintenance mechanism is provided outside the flow path member, and applies an external force to the valve body to maintain the valve body in a closed position where the exhaust flow path is most closed. Specifically, the valve body is provided so as to rotate and move in the opening direction from the closed position by the pressure of the exhaust gas.

According to such a structure, the structure which applies the external force for maintaining a valve body to a closed position to a valve body is realizable with comparatively low heat resistance.
In one embodiment of the present disclosure, the valve body may be provided downstream of the catalyst that purifies the exhaust gas flowing through the exhaust passage. According to such a configuration, the valve body is maintained in the closed position in a state where the pressure of the exhaust gas is low, and the flow of the exhaust gas is inhibited downstream of the catalyst, so that the residence time of the exhaust gas in the catalyst becomes long. Therefore, the temperature of the catalyst can be easily improved.

One aspect of the present disclosure may be configured such that the maintenance mechanism has a maximum load applied to the valve body at the beginning of opening of the valve body. According to such a structure, it can suppress that a valve body begins to open to an opening direction from a closed position in the state where the pressure of waste gas is low.

The following configuration may be an aspect of the present disclosure. That is, the maintenance mechanism includes a first link member, a second link member, and an urging member. The first link member is provided so as to be rotatable with respect to the valve body. The second link member is provided to be rotatable with respect to the flow path member. The urging member urges the valve body in the closing direction. The first link member and the second link member are connected to each other so as to be rotatable. In addition, the configuration in which “the first link member is provided so as to be able to rotate and move with respect to the valve body” includes not only the configuration in which the first link member is directly connected by the valve body, but also the first link member. A configuration in which one link member is indirectly connected by a valve body through a member other than the valve body is also included. Similarly, in the configuration in which “the second link member is provided so as to be rotatable with respect to the flow path member”, the configuration in which the second link member is directly connected by the flow path member is not sufficient. There is also included a configuration in which the second link member is indirectly connected to the flow path member via a member other than the flow path member.

According to such a configuration, in order to rotate the valve body in the opening direction from the closed position, a strong force is required for the valve body. Therefore, for example, compared with a configuration in which the valve body is urged only by the urging member, a force necessary for the valve body to start rotating in the opening direction from the closed position while weakening the urging force of the urging member against the valve body. Can be increased.

It is the figure which showed typically the structure of the exhaust emission purification device of embodiment. 2A is a perspective view of the valve device in a state where the downstream pipe is seen through and the valve body is open, and FIG. 2B is a perspective view of the valve device in a state where the downstream pipe is seen through and the valve body is closed. 3A is a side view of the valve device in a state where the valve body is open, and FIG. 3B is a side view of the valve device in a state where the valve body is closed.

DESCRIPTION OF SYMBOLS 1 ... Flow path member, 2 ... Catalyst, 3 ... Circulation pipe, 4 ... Circulation valve, 5 ... Valve apparatus, 11 ... Upstream pipe, 12 ... Catalyst case, 13 ... Downstream pipe, 50 ... Valve body, 50A ... Main-body part, 50B ... Shaft, 51 ... Rod, 51A ... Link support, 52 ... Stay, 52A, 52B ... Support, 53 ... First link member, 54 ... Second link member, 55 ... Spring, 60, 61 ... Bearings, 7A, 7B, 7C ... shaft, 100 ... exhaust purification device, 121 ... upstream cone part, 122 ... case part, 123 ... downstream cone part.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
[1. Constitution]
An exhaust purification device 100 shown in FIG. 1 is a device for purifying exhaust gas discharged from an internal combustion engine of an automobile. The arrows in FIG. 1 indicate the direction in which the exhaust gas flows.

The exhaust purification device 100 includes a flow path member 1, a catalyst 2, a reflux pipe 3, a reflux valve 4, and a valve device 5.
The flow path member 1 is a part of the exhaust flow path for guiding the exhaust gas discharged from the internal combustion engine to the outside of the automobile, specifically, until the exhaust gas discharged from the internal combustion engine passes through the catalyst 2 and is discharged. The exhaust passage is formed. The flow path member 1 includes an upstream pipe 11 that forms an exhaust flow path upstream of the catalyst 2, a catalyst case 12 that houses the catalyst 2, and a downstream pipe 13 that forms an exhaust flow path downstream of the catalyst 2. . The upstream pipe 11, the catalyst case 12, and the downstream pipe 13 are sections for convenience of explanation, and the sections of the parts constituting the flow path member 1 are not particularly limited.

The upstream pipe 11 and the downstream pipe 13 are straight circular pipes. In this example, the downstream pipe 13 is provided coaxially with the central axis of the upstream pipe 11 and has the same diameter as the upstream pipe 11. The catalyst case 12 has a cylindrical case part 122 having a diameter larger than that of the upstream pipe 11, an upstream cone part 121 that connects the upstream pipe 11 and the case part 122, and a downstream part that connects the case part 122 and the downstream pipe 13. A cone portion 123. The catalyst case 12 is also provided coaxially with the central axis of the upstream pipe 11.

Catalyst 2 is a ceramic carrier carrying a noble metal such as platinum, palladium, or rhodium. The carrier is a filter having a cylindrical outer shape. The catalyst 2 is accommodated in the case portion 122 of the catalyst case 12. The catalyst 2 is configured such that the exhaust gas flowing into the upstream end face of the catalyst 2 flows out from the downstream end face of the catalyst 2. HC, CO, NOx, etc. in the exhaust gas are purified by an oxidation reaction or an oxidation / reduction reaction when passing through the catalyst 2. The exhaust gas purification effect by the catalyst 2 is easily exhibited when the temperature of the exhaust gas passing through the catalyst 2 is increased to some extent. The exhaust purification device 100 of the present embodiment has a configuration using only one catalyst 2.

One end of the reflux tube 3 is connected to the downstream cone portion 123. The recirculation pipe 3 forms a recirculation flow path for introducing exhaust gas from the exhaust flow path downstream of the catalyst 2 to the intake flow path for supplying air to the internal combustion engine. That is, a so-called EGR (Exhaust Gas Recirculation) system is constructed by the reflux pipe 3.

The recirculation valve 4 adjusts the amount of exhaust gas flowing through the recirculation pipe 3. Specifically, the open / close operation of the recirculation valve 4 is controlled by electrical power in accordance with a control signal output from an electronic control device mounted on the automobile.

The valve device 5 opens and closes the exhaust passage downstream of the catalyst 2, specifically, downstream of the branch position between the downstream cone portion 123 and the reflux pipe 3. In this example, the valve device 5 is provided in the downstream pipe 13. Note that the exhaust purification device 100 of the present embodiment has a configuration in which only one valve device that opens and closes the exhaust flow path is used downstream of the catalyst 2, specifically, downstream of the branch position of the reflux pipe 3. .

The downstream pipe 13 is provided with two through holes for supporting a valve body 50 described later. Specifically, as shown in FIGS. 2A and 2B, a bearing 60 and a bearing 61, which will be described later, are inserted through the two through holes.

The valve device 5 includes a valve body 50, a rod 51, a stay 52, a first link member 53, a second link member 54, a spring 55, a bearing 60, a bearing 61, a shaft 7A, A shaft 7B and a shaft 7C are provided. The valve body 50 in the valve device 5 and parts other than a part of the bearing 60 and the bearing 61 are provided outside the downstream pipe 13.

The bearing 60 is a cylindrical member that rotatably supports one of both end portions of the shaft portion 50B of the valve body 50 described later and the rod 51 and supports a stay 52 described later. The bearing 61 is a cylindrical member that rotatably supports the other of both end portions of the shaft portion 50B. The bearing 61 is provided coaxially with the central axis of the bearing 60. Each of the bearing 60 and the bearing 61 and the downstream pipe 13 are fixed by welding.

The valve body 50 is accommodated in the internal space of the downstream pipe 13 and is provided so as to be rotatable relative to the downstream pipe 13 in an exhaust passage formed by the downstream pipe 13. The valve body 50 includes a main body portion 50A and a shaft portion 50B.

The main body 50A is a substantially circular plate-shaped portion that plays a role of changing the flow passage area of the exhaust flow passage in the valve body 50. Specifically, the main body portion 50A is a plate-like portion in which the left and right sides are cut out in a straight line parallel to each other. The reason why such a notch is formed in the main body 50A is to prevent interference between the outer edge of the main body 50A and the inner peripheral surface of the downstream pipe 13 when the valve body 50 rotates. Due to the cutout of the main body portion 50A, there is a gap between the valve body 50 and the downstream pipe 13 even when the valve body 50 (main body portion 50A) is in the closed position where the exhaust passage is most closed. The exhaust passage is not completely blocked. The closed position here is a position where the substantially circular surface of the main body 50A is orthogonal to the central axis of the downstream pipe 13 (in this example, the positions shown in FIGS. 2B and 3B). Due to the gap between the valve body 50 and the downstream pipe 13, the exhaust passage is not completely closed by the valve body 50, and malfunction of the internal combustion engine is prevented. In addition, the part provided with the shaft part 50B in the main body part 50A has a shape in which the left and right sides are further cut out.

As shown in FIGS. 3A and 3B, the shaft portion 50 </ b> B is a rod-shaped portion that plays a role as a rotation shaft in which the main body portion 50 </ b> A rotates in the valve body 50. The shaft portion 50B is fixed to the main body portion 50A with screws at a position shifted from the center of the substantially circular surface of the main body portion 50A. Both end portions of the shaft portion 50 </ b> B are cylindrical, one of which is inserted into the bearing 60 and the other is inserted into the bearing 61. The outer diameters at both ends of the shaft portion 50B are set to be slightly smaller than the inner diameters of the bearing 60 and the bearing 61. In addition, the exhaust gas flowing through the exhaust passage is prevented from leaking from the respective holes of the bearing 60 and the bearing 61 between the outer peripheral surfaces of both ends of the shaft portion 50B and the inner peripheral surfaces of the bearing 60 and the bearing 61. Therefore, the labyrinth structure washer is arranged.

The valve body 50 is arranged in such a direction that the central axes of both end portions of the shaft portion 50B are in the horizontal direction, and the shaft portion 50B is positioned above the center position of the main body portion 50A in the vertical direction. That is, the valve body 50 is provided such that the arc-shaped portion in which the notch is not formed in the main body 50A faces downward in the vertical direction. Therefore, in the state where the valve body 50 is in the closed position, the gap between the downstream pipe 13 and the valve body 50 is small on the lower side in the vertical direction in the internal space of the downstream pipe 13. This is because, when the gap is small, backflow is suppressed when condensed water is generated inside the flow path member 1.

The rod 51 is a member fixed to the shaft portion 50B of the valve body 50 outside the downstream pipe 13, and is a member extending in a direction perpendicular to the central axis of the shaft portion 50B. The rod 51 has a link support portion 51A for supporting the first link member 53 so that the first link member 53 can rotate and move at one end, and the other end is fixed to the shaft portion 50B by a screw (not shown). The shaft portion 50B passes through the bearing 60 and a support portion 52A of a stay 52 described later.

The stay 52 is an L-shaped plate material, and includes a support portion 52A for supporting the bearing 60 and a support portion 52B for supporting the second link member 54 so as to be rotatable. The shaft portion 50B and the bearing 60 are inserted through the support portion 52A. The support part 52B supports the second link member 54 so as to be capable of rotational movement in a state where one end of the second link member 54 is sandwiched from both sides.

The first link member 53 is a rod-shaped member that realizes a toggle mechanism. The toggle mechanism here is a mechanism for applying an external force to the valve body 50 to maintain the valve body 50 in the closed position. One end of the first link member 53 is rotatably supported by the link support portion 51A of the rod 51 via the shaft 7A. Similarly to the first link member 53, the second link member 54 is also a rod-shaped member for realizing a toggle mechanism. One end of the second link member 54 is rotatably supported by the support portion 52B of the stay 52 via the shaft 7B. The other end of the first link member 53 and the other end of the second link member 54 are connected to each other via a shaft 7C so as to be rotatable.

As described above, the rod 51, the stay 52, the first link member 53, and the second link member 54 are connected to each other so as to be able to rotate, thereby forming a link type toggle mechanism (link mechanism).

The spring 55 is a coil spring and is a member for urging the valve body 50 in the closing direction B shown in FIG. 3B. The closing direction B here refers to a direction in which the valve body 50 is closed so that the exhaust passage is closed. The spring 55 is provided to act on the support portion 52 </ b> B of the stay 52 and the second link member 54. Specifically, the spring 55 has the same number of turns on both sides of the spring 55 with the second link member 54 interposed therebetween, and is symmetrical with the second link member 54 interposed therebetween. The number of turns of the spring 55 is the same on both sides of the second link member 54. When the number of turns of the spring 55 is shifted to the side opposite to the downstream pipe 13 side, the second link member 54 is correspondingly increased. This is because the second link member 54 and other parts are likely to interfere with each other when the position is shifted toward the downstream pipe 13 side. On the contrary, when the number of turns of the spring 55 is shifted toward the downstream pipe 13 side, the position of the second link member 54 is shifted to the opposite side to the downstream pipe 13 side, thereby increasing the size of the entire valve device 5. Because.

Thus, the valve body 50 is rotatably supported by the bearing 60 and the bearing 61 in the internal space of the downstream pipe 13 with the shaft portion 50B as the rotation axis. Specifically, as shown in FIG. 3B, the valve body 50 is positioned at the closed position by the urging force of the spring 55 in a state where the pressure of the exhaust gas that rotates and moves the valve body 50 is not applied. In the state where the valve body 50 is in the closed position, the link angle that is an angle formed by the first link member 53 and the second link member 54 is the largest (an angle close to 180 degrees in this example). Therefore, a strong external force is required to rotate the valve body 50 in the opening direction A as shown in FIG. 3A when the valve body 50 is in the closed position.

When sufficient exhaust gas pressure is applied to the valve body 50 to rotate the valve body 50, the main body 50A moves in the opening direction A and the shaft 50B rotates as shown in FIG. 3A. In conjunction with this operation, the rod 51 fixed to the shaft portion 50B also rotates about the shaft portion 50B, and the first link member 53 and the second link member 54 also rotate. At this time, the link angle decreases as the valve body 50 rotates in the opening direction A.

When the pressure of the exhaust gas decreases, the valve body 50 rotates and moves in the closing direction B by the urging force of the spring 55. That is, the valve body 50 rotates and moves to a position corresponding to the pressure of the exhaust gas, and changes the flow passage area of the exhaust flow passage.

[2. effect]
According to the embodiment detailed above, the following effects can be obtained.
(1a) The valve body 50 is provided so as to be rotatable relative to the downstream pipe 13 of the flow path member 1 in the exhaust flow path (relative to the downstream pipe 13). When the pressure of the exhaust gas that rotates and moves the valve body 50 is not applied, the valve body 50 is positioned at the closed position by the urging force of the spring 55. When sufficient exhaust gas pressure is applied to the valve body 50 to rotate the valve body 50, the main body portion 50A moves in the direction of the opening direction A and the shaft portion 50B rotates. In conjunction with this operation, the rod 51, the first link member 53, and the second link member 54 also rotate. When the pressure of the exhaust gas decreases, the valve body 50 rotates and moves in the closing direction B by the urging force of the spring 55. Further, the valve body 50 and the rod 51, the stay 52, the first link member 53, the second link member 54, the spring 55, and the shaft, which are components of the valve device 5 excluding a part of the bearing 60 and the bearing 61. 7A, the shaft 7B, and the shaft 7C are provided outside the downstream pipe 13.

According to such a configuration, the configuration of the valve device 5 that applies the urging force of the spring 55 to the valve body 50 can be realized with relatively low heat resistance. For this reason, compared with the structure with which the valve body 50 and the component of the valve apparatus 5 except a part of bearing 60 and the bearing 61 are provided in the inside of the downstream pipe 13, the thermal expansion of the said component is suppressed. Is done.

For example, in the case where the component is housed in the downstream pipe 13 together with the valve body 50, the temperature of the exhaust gas is very high immediately below the catalyst 2, so that the rotationally moving portion of each component is expanded by heat, or a spring The problem that the 55 characteristic changes may arise. On the other hand, according to the configuration of the present embodiment, since the spring 55 that biases the valve body 50 is provided outside the downstream pipe 13, such a problem can be made difficult to occur.

Therefore, for example, it is possible to reduce the amount of heat-resistant material such as inconel as the material of the spring 55, and to reduce the cost.
In addition, for example, in order to absorb the thermal expansion of the rotationally moving portion in each component, it is possible to eliminate a cushioning material such as a wire mesh provided between each component, thereby reducing the number of components and the cost. Can be planned. In addition, for example, it is possible to use aluminum or resin parts for each component, which can further reduce the weight. In addition, since only the valve body 50 is provided in the exhaust flow path and the heat capacity can be reduced, the temperature reduction of the exhaust gas can be suppressed.

Further, since the valve body 50 rotates according to the pressure of the exhaust gas, it is not necessary to provide a mechanism for applying an external force for driving the valve body 50, for example, an electrical mechanism using a motor or a wire. Moreover, since the valve body 50 opens and closes according to the pressure of exhaust gas, it is not necessary to use sensors for detecting the timing for opening and closing the valve body 50. Therefore, a mechanism for rotating the valve body 50 can be realized with a simple configuration.

Further, the rod 51, the first link member 53, the second link member 54, the spring 55, the shaft 7A, the shaft 7B, and the shaft 7C are held only by the stay 52, so that these are configured as one assembly. The For this reason, the stay 52 can facilitate the assembly of the valve device 5 to the downstream pipe 13.

(1b) A valve body 50 is provided downstream of the catalyst 2 for purifying exhaust gas flowing through the exhaust passage. According to such a configuration, the valve body 50 is maintained at the closed position in a state where the pressure of the exhaust gas is low, and the flow of the exhaust gas is inhibited downstream of the catalyst 2, so that the residence time of the exhaust gas in the catalyst 2 becomes long. Therefore, the temperature of the catalyst 2 can be easily improved.

Especially in the automobile field, the level required for catalyst purification performance has become stricter due to compliance with exhaust gas regulations. Therefore, in addition to the conventional concept of “heat insulation”, “improving warm-up” is also required.

In response to such a demand, according to the valve device 5 of the present embodiment, the valve body 50 is biased in the closing direction B by the spring 55 in a state where the pressure of the exhaust gas is low as in the idling state immediately after the internal combustion engine is started. The force exceeds the force with which the exhaust gas opens the valve body 50, and the valve body 50 is in the closed position. For this reason, the back pressure of the exhaust passage increases, and the residence time of the exhaust gas in the vicinity of the catalyst 2 becomes longer. Therefore, an increase in the bed temperature of the catalyst 2 can be promoted.

On the other hand, when the rotational speed of the internal combustion engine increases and the pressure of the exhaust gas increases, the exhaust gas increases the force in the opening direction A by the valve body 50, and the valve body 50 rotates and moves in the opening direction A. For this reason, the pressure loss of the exhaust passage can be suppressed.

(1c) The valve device 5 includes a first link member 53, a second link member 54, a spring 55, a bearing 60, a bearing 61, a shaft 7A, a shaft 7B, and a shaft 7C. . The first link member 53 is rotatably provided relative to the valve body 50 and the rod 51 (based on the valve body 50 and the rod 51) via the shaft 7A. The second link member 54 is provided to be rotatable relative to the stay 52 (with respect to the stay 52) via the shaft 7B. The spring 55 biases the valve body 50 in the closing direction B. The first link member 53 and the second link member 54 are connected to each other via a shaft 7C so as to be capable of rotational movement. In the state where the valve body 50 is in the closed position, the link angle, which is the angle formed by the first link member 53 and the second link member 54, is the largest, and in this example is close to 180 degrees. Therefore, a strong external force is required to rotate the valve body 50 in the opening direction A when the valve body 50 is in the closed position. That is, the valve device 5 is configured so that the load applied to the valve body 50 at the beginning of opening of the valve body 50 is maximized. The maximum here means the local maximum when the load applied to the valve body 50 in the closing direction is regarded as a function of the rotational movement amount (angle) of the valve body 50 in the opening direction, and is not necessarily limited to the entire area. Does not necessarily match. According to such a configuration, the urging force in the closing direction B against the valve body 50 can be increased as the valve body 50 opens in the opening direction A from the closed position. That is, for example, as compared with a configuration in which the valve body 50 is biased only by the spring 55, the force necessary for the valve body 50 to start rotating in the opening direction A from the closed position is increased while weakening the force of the spring 55. be able to. Thereby, it can suppress that the valve body 50 begins to open to the opening direction A from a closed position in the state where the pressure of waste gas is low.

(1d) The first link member 53 and the second link member 54 protrude to the opposite side to the side where the shaft portion 50B of the valve body 50 is provided in the vertical direction. According to such a configuration, the protruding amount of the first link member 53 and the second link member 54 with respect to the downstream pipe 13 can be suppressed.

In the present embodiment, the downstream pipe 13 corresponds to an example of a flow path member, and the rod 51, the stay 52, the first link member 53, the second link member 54, the spring 55, the shaft 7A, the shaft 7B, and the shaft. 7C corresponds to an example of a maintenance mechanism. The spring 55 corresponds to an example of an urging member.

[3. Other Embodiments]
As mentioned above, although embodiment of this indication was described, it cannot be overemphasized that this indication can take various forms, without being limited to the above-mentioned embodiment.

(2a) In the above embodiment, the configuration shown in FIG. 1 is exemplified as the flow path member having the exhaust flow path in which the valve body is provided, but the configuration of the flow path member is not limited to this. For example, the structure which has an exhaust flow path inside a cross section other than circular may be sufficient.

(2b) In the above embodiment, the exhaust purification device 100 has been illustrated with the configuration including the reflux pipe 3 and the reflux valve 4. However, the exhaust purification device may have a configuration without the reflux pipe and the valve.

(2c) In the above embodiment, the configuration in which the valve body 50 is provided downstream of the catalyst 2 for purifying exhaust gas is exemplified, but the position of the valve body is not limited to this. For example, the valve body may be provided upstream of the catalyst 2, and may be provided at other positions in the exhaust passage such as downstream of a DPF (Diesel Particulate Filter) or GPF (Gasoline Particulate Filter). Also good.

(2d) In the above embodiment, the configuration in which the spring 55 provided in the valve device 5 is a coil spring is exemplified, but the type of the spring is not particularly limited. For example, a so-called double torsion spring having a shape in which two left and right coil springs are combined may be used for the valve device. Moreover, in the said embodiment, although the structure provided in the valve apparatus 5 so that the spring 55 acted on the stay 52 and the 2nd link member 54 was illustrated, the attachment position of a spring is not specifically limited. For example, a spring may be provided so as to act on the rod 51 and the first link member 53, and for example, a spring may be provided so as to act on the first link member 53 and the second link member 54. It may be. Also, an urging member other than a spring, such as an elastic body, may be used.

(2e) In the above embodiment, a link-type toggle mechanism is exemplified as a maintenance mechanism that applies an external force to the valve body 50 to maintain the valve body 50 in the closed position, but the configuration of the maintenance mechanism is limited to this. It is not a thing. For example, the maintenance mechanism may include a biasing member that biases the valve body in the closing direction and a resistance member that becomes resistance when the valve body rotates in the opening direction from the closed position. The resistance member here is, for example, a member (for example, a leaf spring) that is positioned so as to prevent rotational movement of the valve body in the opening direction and that elastically deforms along with the rotational movement of the valve body, thereby allowing the rotational movement of the valve body. Etc.). Even with such a maintenance mechanism, the load applied to the valve body at the beginning of opening of the valve body can be maximized. Further, the maintenance mechanism may be configured such that the urging force in the closing direction with respect to the valve element increases as the valve element opens, for example, the valve element may be urged in the closing direction only by the urging member or the weight.

(2f) In the above embodiment, the valve body 50 having the configuration in which the shaft portion 50B is provided at a position shifted from the center of the surface of the main body portion 50A is illustrated, but the configuration of the valve body is not limited to this. . For example, the valve body may be configured such that the main body portion rotates along the center line of the surface. In this case, since interference between the outer edge of the main body portion of the valve body and the inner surface of the flow path member is suppressed, the shape of the main body portion can be made, for example, a circle or a shape closer to a circle.

(2g) The functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

Claims

A flow path member having an exhaust flow path therein;
A valve body capable of rotating relative to the flow path member in the exhaust flow path;
A maintenance mechanism that is provided outside the flow path member and applies an external force to the valve body to maintain the valve body in a closed position where the exhaust flow path is most closed;
With
The valve device for an exhaust passage, wherein the valve body is provided so as to rotate and move in the opening direction from the closed position by the pressure of exhaust gas.
It is the valve device for exhaust passages according to claim 1,
The valve device for an exhaust passage, wherein the valve body is provided downstream of a catalyst that purifies exhaust gas flowing through the exhaust passage.
The exhaust passage valve device according to claim 1 or 2,
The maintenance mechanism is a valve device for an exhaust passage configured such that a load applied to the valve body at the beginning of opening of the valve body is maximized.
It is the valve device for exhaust passages according to any one of claims 1 to 3,
The maintenance mechanism is
A first link member provided rotatably with respect to the valve body;
A second link member provided rotatably with respect to the flow path member;
A biasing member for biasing the valve body in the closing direction;
With
The exhaust flow path valve device, wherein the first link member and the second link member are connected to each other so as to be rotatable.