JP2018053807A - Exhaust control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the peculiar flow of exhaust gas as a main factor for the leakage of the exhaust gas.SOLUTION: An exhaust control valve includes a valve body 3 having a flow path hole 2 in which exhaust gas distributes, a valve element 4 turnably arranged in the flow path hole, a valve stem 5 fixed to the valve element and protruded from the valve element for determining a turning center X of the valve element, a valve stem hole 8 formed in the valve body for the valve stem to be inserted therethrough, and a seal member 22 for sealing a clearance 18 between the valve stem and the valve stem hole, the seal member including a small-diameter seal member 23 and a large-diameter seal member 24 arranged in the clearance to form a labyrinth seal, the small-diameter seal member 23 being fixed to the valve stem with interference fit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust control valve for controlling the flow rate of exhaust gas flowing through an exhaust passage of an engine, and is particularly suitable for application to an exhaust brake valve that increases the engine braking force by closing the exhaust passage during vehicle braking. Related to an exhaust control valve.

  A large vehicle such as a truck is equipped with an exhaust brake valve for the purpose of increasing the engine braking force during vehicle braking. The exhaust brake valve typically includes a rotatable valve body, and closes the exhaust passage of the engine by closing the valve body via a valve shaft, thereby enhancing the engine brake force. Yes.

  The valve shaft is inserted into a valve shaft hole formed in the valve body, and is supported rotatably in the valve shaft hole. That is, a bearing for rotatably supporting the valve shaft is provided in the valve shaft hole. In addition to this, a seal member for sealing a gap between the valve shaft and the valve shaft hole is provided in the valve shaft hole.

  As a seal member, one having a small-diameter seal member and a large-diameter seal member arranged so as to form a labyrinth seal is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-119498

  In such an exhaust brake valve, when the valve body is closed, the upstream exhaust pressure becomes high, and there is a concern that the exhaust gas leaks to the outside through the gap between the valve shaft and the valve shaft hole. In order to suppress this leakage as much as possible, the sealing member is provided.

  On the other hand, as a result of intensive studies, the present inventors have newly found that there is a unique exhaust gas flow that is a main factor of exhaust gas leakage. The conventional seal member cannot effectively block such a specific exhaust gas flow, and as a result, it is difficult to obtain a sufficient seal performance.

  Accordingly, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an exhaust control valve capable of effectively blocking a flow of a specific exhaust gas that is a main factor of exhaust gas leakage.

According to one aspect of the invention,
A valve body having a passage hole through which exhaust gas flows;
A valve body rotatably disposed in the flow path hole;
A valve shaft fixed to the valve body, protruding from the valve body, and defining a rotation center of the valve body;
A valve shaft hole formed in the valve body and through which the valve shaft is inserted;
A seal member for sealing a gap between the valve shaft and the valve shaft hole;
With
The seal member includes a small-diameter seal member and a large-diameter seal member disposed in the gap so as to form a labyrinth seal;
An exhaust control valve is provided in which the small-diameter seal member is fixed to the valve shaft by an interference fit.

Preferably, the seal member includes at least two small-diameter seal members and at least one large-diameter seal member, and the small-diameter seal members and the large-diameter seal members are alternately arranged in the axial direction,
Of the at least two small-diameter seal members, at least the small-diameter seal member closest to the flow path hole is fixed to the valve shaft by an interference fit.

  Preferably, the small diameter seal member is fixed to the valve shaft by press fitting or shrink fitting.

  Preferably, the small-diameter seal member is a small-diameter seal washer, and the large-diameter seal member is a large-diameter seal washer.

  ADVANTAGE OF THE INVENTION According to this invention, the flow of the characteristic exhaust gas used as the main factor of exhaust gas leakage can be blocked | prevented effectively.

It is a fragmentary sectional view showing the whole exhaust brake valve composition concerning this embodiment. It is a principal part expanded sectional view of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The present invention relates to an exhaust control valve for controlling the flow rate of exhaust gas flowing through an exhaust passage of an engine (internal combustion engine). This embodiment described below is an example in which the present invention is applied to an exhaust brake valve. As is well known, an exhaust brake valve is a valve device that closes an exhaust passage during vehicle braking to stop the flow of exhaust gas and increase engine braking force. However, the present invention is not limited to the exhaust brake valve and can be widely applied as a valve installed in the exhaust passage. Vehicles equipped with exhaust brake valves are mainly large vehicles such as trucks and buses, and engines to which exhaust brake valves are applied are mainly diesel engines. However, the type of vehicle and engine is arbitrary.

  FIG. 1 shows an overall configuration of an exhaust brake valve 1 according to the present embodiment. The exhaust brake valve 1 is fixed to the valve body 4 having a valve body 3 having a flow passage hole 2 through which exhaust gas flows, a valve body 4 rotatably disposed in the flow passage hole 2, and the valve body 4. And valve shafts 5 and 6 that define the rotation center X of the valve body 4.

  There is a hole center O of the channel hole 2 on the rotation center X, and an orthogonal axis Y perpendicular to the rotation center X is defined at the hole center O. The left side of the drawing with respect to the orthogonal axis Y is the left, and the right side of the drawing is the right. The longitudinal direction of the rotation center X is referred to as the axial direction. A radial direction based on the rotation center X may be simply referred to as a radial direction. In the axial direction, the direction approaching the hole center O is the inner side, and the direction away from the hole center O is the outer side. It should be noted that such expressions are merely defined for convenience in the illustrated arrangement for easy understanding. The exhaust brake valve 1 has a generally symmetrical configuration. The flow direction of the exhaust gas in the flow path hole 2 is a direction orthogonal to the rotation center X and the orthogonal axis Y, that is, the front and back direction of the paper.

  The valve body 3 has a substantially rectangular outer shape and a circular flow path hole 2, and the exhaust gas is circulated in the flow path 2 in the above-described direction. A plurality (four in this embodiment) of bolt insertion holes 7 are provided on the outer side in the radial direction of the flow path hole 2 with respect to the hole center O to be flange-connected in the middle of an exhaust pipe (not shown) of the engine. . The exhaust pipe and the valve main body 3 are coaxially connected, and the exhaust pipe and the valve main body 3 define an exhaust passage of the engine.

  The valve body 4 is a circular butterfly valve type valve body adapted to the flow path hole 2 and is made of a plate-like member (particularly a metal plate). The valve body 4 is arranged coaxially with the hole center O.

  Valve shafts 5 and 6 are fixed to the left and right sides of the valve body 4. In the case of the present embodiment, a halved slit is provided at the axially inner ends of the valve shafts 5 and 6, and the valve body 4 is inserted into the slit and fixed by welding. However, such a fixing method is arbitrary, and may be fixed by, for example, bolting. In the case of this embodiment, the valve shaft is composed of two valve shafts 5 and 6 divided into left and right, but may be composed of one valve shaft. The left and right valve shafts 5 and 6 protrude from the valve body 4 in the axial direction outside, that is, the left and right sides, respectively.

  These protruding portions of the valve shafts 5 and 6 are inserted into valve shaft holes 8 and 9 formed in the valve body 3. Convex portions 10 and 11 projecting outward in the axial direction are integrally formed on the left and right sides of the valve body 3. The valve shaft holes 8 and 9 extend from the end surfaces on the outer side in the axial direction of the convex portions 10 and 11 to the flow path hole 2 so as to be coaxial with the rotation center X and penetrate in the axial direction. The inner diameter of the valve shaft holes 8 and 9 is larger than the outer diameter of the valve shafts 5 and 6, and relatively large gaps 18 and 19 are formed between the valve shaft holes 8 and 9 and the valve shafts 5 and 6. Yes.

  Cover plates 12 and 13 for closing the valve shaft holes 8 and 9 are attached to the convex portions 10 and 11 by a plurality of bolts 14 and 15. An insertion hole 16 is provided at the center of the left lid plate 12, and the left valve shaft 5 protrudes to the outside through the insertion hole 16. An operation lever 17 is fixed to the protruding end. When the operation lever 17 is rotated around the rotation center X by an actuator (not shown), the valve shafts 5 and 6 and the valve body 4 are integrally rotated around the rotation center X, that is, opened and closed. The

  Thus, the left valve shaft 5 is a drive-side valve shaft to which a driving force for rotation is applied. On the other hand, the right valve shaft 6 is a driven valve shaft that is passively rotated as the valve body 4 rotates. Therefore, the right valve shaft 6 does not protrude to the outside, and the right lid plate 13 is not provided with the insertion hole 16.

  The configurations in the left and right gaps 18 and 19 and the valve shaft holes 8 and 9 are the same except that they are symmetrical. Therefore, hereinafter, the configuration on the left side will be mainly described, and the description on the configuration on the right side will be basically omitted.

  2, the retainer 20, the bearing 21, and the seal member 22 are arranged coaxially with respect to the rotation center X in the gap 18 in this order from the inner side to the outer side.

  In the case of this embodiment, the bearing 21 is a sliding bearing, and in particular, a metallic tubular bush. The bearing 21 is slidably fitted to the valve shaft 5 and the valve shaft hole 8, and supports the valve shaft 5 so as to be rotatable.

  Although the retainer 20 is also a tubular member, its use is different from that of the bearing 21 and is mainly used for the purpose of filling the axial gap in the valve shaft hole 8 or supporting the valve shaft 5 in an auxiliary manner. . The retainer 20 is a component with relatively low accuracy and is relatively loosely fitted to the valve shaft 5 and the valve shaft hole 8. The retainer 20 may be omitted.

  The seal member 22 includes a small-diameter seal member and a large-diameter seal member disposed in the gap 18 so as to form a labyrinth seal. In the present embodiment, the small-diameter seal member includes a small-diameter seal washer 23, and the large-diameter seal member includes a large-diameter seal washer 24. Both seal washers 23 and 24 are annular members made of thin plates. The small-diameter seal washer 23 is smaller in both inner and outer diameters than the large-diameter seal washer 24.

  In the present embodiment, the seal member 22 includes at least two small-diameter seal washers 23 and at least one large-diameter seal washer 24. Specifically, the seal member 22 includes two small diameter seal washers 23 and two large diameter seal washers 24. These small diameter seal washers 23 and large diameter seal washers 24 are alternately arranged one by one in the axial direction. In this embodiment, the small-diameter seal washer 23 (23A), the large-diameter seal washer 24, the small-diameter seal washer 23 (23B), and the large-diameter seal washer 24 are arranged in this order from the inner side to the outer side in the axial direction.

  In FIG. 2, the size and presence / absence of the gaps between the members are exaggerated. In the axial direction, a minimum gap is formed to enable the valve shafts 5 and 6 and the valve body 4 to rotate. The size of the axial gap is not so important in this embodiment. The axial clearance is formed so as to minimize backlash in the axial direction of the valve shafts 5 and 6 and the valve body 4 and to allow smooth rotation of the valve shafts 5 and 6 and the valve body 4. Yes. The axial length of the retainer 20 is determined so as to achieve such an optimal axial clearance.

  Next, the radial gap will be described. Since the retainer 20 does not need to be highly accurate, a relatively large gap is formed between the retainer 20 and the valve shaft 5 and between the retainer 20 and the valve shaft hole 8. The retainer 20 is in a relatively loose clearance fit with respect to the valve shaft 5 and the valve shaft hole 8.

  The bearing 21 needs to support the valve shaft 5 so that the valve shaft 5 can be smoothly rotated with as little shaft displacement as possible. For this reason, the bearing 21 is relatively tightly fitted to the valve shaft hole 8. The clearance between the bearing 21 and the valve shaft hole 8 is set to a limit that allows the bearing 21 to slide or a size that achieves a relatively high-quality fitting (in the drawing, the clearance is expressed as no clearance). . On the other hand, in order to allow a smooth sliding rotation of the valve shaft 5 with respect to the bearing 21, the bearing 21 is in a loose fit state with respect to the valve shaft 5 than in the valve shaft hole 8. The gap between the bearing 21 and the valve shaft 5 is larger than the gap between the bearing 21 and the valve shaft hole 8.

  The clearance between the large-diameter seal washer 24 and the valve shaft hole 8 has a marginal size or relatively high-quality fit that allows the large-diameter seal washer 24 to slide relative to the valve shaft hole 8 during assembly. The size is such that it is achieved (represented as no gaps in the figure). The large-diameter seal washer 24 is relatively tightly fitted into the valve shaft hole 8. On the other hand, the gap between the large-diameter seal washer 24 and the valve shaft 5 defines a part of the meandering passage for the exhaust gas to be leaked, so that the gap between the large-diameter seal washer 24 and the valve shaft hole 8 is larger. Has also been enlarged. The inner diameter of the large-diameter seal washer 24 is larger than the outer diameter of the valve shaft 5, and the large-diameter seal washer 24 is loosely fitted into the valve shaft 5. A state in which exhaust gas flows through the meandering passage is indicated by a virtual line a.

  The gap between the small-diameter seal washer 23 and the valve shaft hole 8 also defines a part of the meandering passage for the exhaust gas to be leaked, so that it is as large as the gap between the large-diameter seal washer 24 and the valve shaft 5. Is set. The outer diameter of the small-diameter seal washer 23 is smaller than the inner diameter of the valve shaft hole 8, and the small-diameter seal washer 23 is loosely fitted into the valve shaft hole 8.

  On the other hand, although it is characteristic, there is no gap between the small-diameter seal washer 23 and the valve shaft 5. This is because the small-diameter seal washer 23 is fixed to the valve shaft 5 by an interference fit. In the present embodiment, the two small-diameter seal washers 23 (23A, 23B) are both fixed to the valve shaft 5 by an interference fit. For example, the small-diameter seal washer 23 is fixed to the valve shaft 5 by press fitting or shrink fitting. As another interference fitting method, cold fitting or the like is also conceivable.

  When at least two small-diameter seal washers 23 are provided, for the reason described later, at least the small-diameter seal washer 23 (23A) closest to the flow path hole 8, that is, the small-diameter seal washer 23 (23A) positioned closest to the inner side in the axial direction is It is preferably fixed to the valve shaft 5 by an interference fit. In this embodiment, in addition to the small-diameter seal washer 23 (23A) located on the innermost side in the axial direction, the small-diameter seal washer 23 (23B) located on the outer side in the axial direction is also fixed by an interference fit. Yes. However, the small-diameter seal washer 23 (23B) positioned on the outer side in the axial direction can be modified with a clearance fit instead of an interference fit. Thereby, a difference can be given to a fitting degree between both the small diameter seal washers 23.

  By providing the seal member 22 that forms the labyrinth seal as described above, the seal is compared with a normal seal member (for example, using an O-ring or the like) that seals by pressing the valve shaft hole 8 and the valve shaft 5. Compatibility and valve operation can be easily performed.

  A gap between the valve shaft 5 and the insertion hole 16 exists outside the seal member 22 in the axial direction. This gap is larger than the gap between the members described above.

  When the exhaust brake valve 1 is operated, the valve body 4 is closed (fully closed) so as to close the flow path hole 2 leaving a slight opening as shown in FIG. At this time, the exhaust pressure upstream of the valve body 4 becomes high, and the exhaust gas tends to leak outside through the gaps 18 and 19 between the valve shafts 5 and 6 and the valve shaft holes 8 and 9. For the right gap 19, the valve shaft hole 9 is closed by the cover plate 13, so there is no possibility of exhaust gas leakage. However, as for the left gap 18, there is a gap between the insertion hole 16 of the cover plate 12 and the valve shaft 5, so that exhaust gas may leak out from here.

  On the other hand, as a result of intensive studies, the present inventors have newly found that there is a unique exhaust gas flow that is a main factor of exhaust gas leakage. This specific flow of exhaust gas is a linear flow toward the outside in the axial direction along the outer peripheral surface of the valve shaft 5 as indicated by a virtual line b in FIG. This flow b can also be said to be a flow that flows in the axially outward direction through the central portion of the gap 18. The flow b passes through the clearance between the retainer 20 and the valve shaft 5 and the clearance between the bearing 21 and the valve shaft 5 in order, and proceeds toward the small-diameter seal washer 23 (23A) located on the innermost side in the axial direction.

  In the conventional labyrinth seal, there is a considerable gap between the small-diameter seal washer and the valve shaft. For this reason, there is a risk of exhaust gas leaking outside through this gap. In the conventional labyrinth seal, the gap between the small-diameter seal washer and the valve shaft has the same size as the gap between the large-diameter seal washer and the valve shaft hole. Therefore, the linear flow b reaching the small-diameter seal washer includes a gap between the small-diameter seal washer and the valve shaft, a gap between the large-diameter seal washer and the valve shaft, and a gap between the valve shaft and the insertion hole. There is a possibility of passing straight through and leaking outside.

  However, in this embodiment, the small diameter seal washer 23 is fixed to the valve shaft 5 by an interference fit, and the gap between the small diameter seal washer 23 and the valve shaft 5 is eliminated. Therefore, the linear flow b can be prevented and the flow b can be guided to the meandering passage formed by the labyrinth seal. Therefore, it is possible to effectively prevent the flow of the specific exhaust gas that becomes the main factor of the exhaust gas leakage, and to obtain a sufficient sealing performance stably.

  In the labyrinth seal as described above, as the number of small-diameter seal washers 23 and large-diameter seal washers 24 increases, the number of bends in the meandering passage increases, which is advantageous in improving the seal performance. In the present embodiment, at least two (specifically two) small-diameter seal washers 23 and at least one (specifically two) large-diameter seal washers 24 are provided. Compared to the case, the sealing performance can be improved.

  Further, in this embodiment, the small-diameter seal washer 23 (23A) positioned at the most inner side in the axial direction is fixed to the valve shaft 5 by an interference fit, so that the linear flow b is the most upstream side of the meandering passage. And the flow b can be effectively blocked.

  In this embodiment, the other small-diameter seal washers 23 (23B) are also fixed to the valve shaft 5 by an interference fit, and in particular, all the small-diameter seal washers 23 are fixed to the valve shaft 5 by an interference fit. Therefore, the gap between the valve shaft 5 and all the small-diameter seal washers 23 that are interference-fitted can be eliminated, and the gas can be prevented from flowing through the gap. And gas can be reliably guided to the meandering passage to improve the sealing performance.

  Here, with respect to the arrangement of the small-diameter seal washer 23 and the large-diameter seal washer 24, it is effective to prevent the linear flow b at the earliest stage. It is preferable to arrange the first small-diameter seal washer 23 on the inner side in the axial direction from the first large-diameter seal washer 24.

  In this embodiment, the small-diameter seal member and the large-diameter seal member are formed from the small-diameter seal washer 23 and the large-diameter seal washer 24 having a simple structure, so that each seal member can be manufactured at low cost.

  As mentioned above, although embodiment of this invention was described in detail, embodiment of this invention is not restricted to the above-mentioned thing, For example, the following other embodiments are also possible.

  (1) Although the plurality of small diameter seal washers 23 are all interference fits in the above embodiment, the type and number of small diameter seal washers 23 that are interference fits are arbitrary. As described above, the small diameter seal washer 23 (23A) located on the innermost side in the axial direction is preferably an interference fit, but this is not necessarily the case. The small diameter seal washer 23 (23A) located on the innermost side in the axial direction may not be an interference fit, that is, may be a gap fit, and the other small diameter seal washer 23 (23B) located on the outer side in the axial direction may be an interference fit.

  (2) The small-diameter seal member and the large-diameter seal member are not limited to the small-diameter seal washer 23 and the large-diameter seal washer 24, and may be formed of seal members having other configurations. Also, the number of small diameter seal members and large diameter seal members can be changed.

  (3) The valve element does not necessarily have to be a butterfly valve type valve element, for example, a ball valve type valve element.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Exhaust brake valve 2 Flow path hole 3 Valve body 4 Valve body 5 Valve shaft 8 Valve shaft hole 18 Clearance 22 Seal member 23 Small diameter seal washer 24 Large diameter seal washer X Center of rotation

Claims (4)

A valve body having a passage hole through which exhaust gas flows;
A valve body rotatably disposed in the flow path hole;
A valve shaft fixed to the valve body, protruding from the valve body, and defining a rotation center of the valve body;
A valve shaft hole formed in the valve body and through which the valve shaft is inserted;
A seal member for sealing a gap between the valve shaft and the valve shaft hole;
With
The seal member includes a small-diameter seal member and a large-diameter seal member disposed in the gap so as to form a labyrinth seal;
The exhaust control valve, wherein the small-diameter seal member is fixed to the valve shaft by an interference fit. The seal member includes at least two small-diameter seal members and at least one large-diameter seal member, and the small-diameter seal members and the large-diameter seal members are alternately arranged in the axial direction,
The exhaust control valve according to claim 1, wherein, of at least two small-diameter seal members, at least the small-diameter seal member closest to the flow path hole is fixed to the valve shaft by an interference fit. The exhaust control valve according to claim 1 or 2, wherein the small-diameter seal member is fixed to the valve shaft by press-fitting or shrink fitting. The exhaust control valve according to any one of claims 1 to 3, wherein the small-diameter seal member is a small-diameter seal washer, and the large-diameter seal member is a large-diameter seal washer.

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