JP2012041886A - Shaft seal structure for exhaust valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft seal structure for an exhaust valve which is improved so as to clearly improve the sealing performance with further inventive idea while using labyrinth seal having many advantages.SOLUTION: The shaft seal structure for the exhaust valve has a valve body 4 opened and closed to an internal passage 3 and a ring-shaped seal S fitted between the valve shaft 2 and a bearing part 5 and is equipped with a fastening mechanism 10 compressing the ring shaped seal S in the axis center P direction. The valve body 4 is supported by a valve shaft 2 supported removably by a valve case 1. The ring-shaped seal S is constituted so that a first ring plate 8 structured by laminating a metal material 8a and an inorganic heat resisting material 8b, tightly and externally fitted to the valve shaft 2 and loosely and internally fitted to the bearing part 5 and a second ring plate 9 structured by laminating a metal material 9a and an inorganic heat resisting material 9b, loosely and externally fitted to the valve shaft 2 and tightly and internally fitted to the bearing part 5 are alternately arranged to be laminated in the axial center direction, wherein a cross-sectional shape of the first and the second ring plates 8, 9 in the diameter direction about axis P is set to a bent shape to be projected in the axis center P direction of the valve shaft 2.

Description

  The present invention relates to a shaft seal structure for an exhaust valve that opens and closes an exhaust flow passage of an engine, such as an exhaust brake of a four-wheeled vehicle or a two-wheeled vehicle.

  As an example in which this type of exhaust valve shaft seal structure is applied, as disclosed in Patent Document 1, an exhaust brake valve provided in an exhaust pipe of an automobile engine, or Patent Document 2 discloses. As described above, an exhaust valve seal structure provided in an exhaust passage of an engine is known. These are all valves for opening and closing the exhaust passage and adjusting the opening.

  FIG. 7 shows an actual structure example of the shaft seal structure for the exhaust valve. That is, a plate-like valve body 14 that opens and closes the internal flow path 13 of the valve case 11 is attached to a pair of valve shafts 12 a and 12 b supported by the valve case 11 constituting the exhaust valve V via the bearing 17. The angle of the valve element 14 with respect to the internal flow path 13 is changed by rotating the valve shaft 12a on the drive side using an actuator, and the internal flow path 13 is opened and closed, or the opening degree is controlled. Thus, the presence / absence of the exhaust brake and the degree of use can be adjusted by the exhaust resistance pressure of the engine.

  In the above-described exhaust valve V, the drive-side valve shaft 12a, which may cause exhaust leakage, is provided with a labyrinth seal 15 between the valve case 11 and the outside of the bearing 17 to form an exhaust valve shaft seal structure. ing. And the outer end side of the valve shaft 12b on the driven side is configured to be equipped with a plug so that exhaust leakage to the outside does not occur by bolting the lid plate 16 to the valve case 11. For reference (FIG. 6), the upper and lower relatively thick shaft portions sandwiching the valve body 14 are referred to as the large diameter shaft portion 12b, and the relatively thin diameter upper end shaft portion is the small diameter shaft portion 12a. May be referred to.

  As shown in FIG. 6, the labyrinth seal 15 is tightly fitted on the valve shaft 12a, and is loosely fitted on the valve shaft 12a by two first ring plates 18 that are loosely fitted on the valve case 11. The two second ring plates 19 tightly fitted in the valve case 11 are alternately stacked in the direction of the axis P of the valve shafts 12a and 12b. It has the advantage of being simple in structure, heat resistant and inexpensive. However, exhaust leaks cannot be eliminated at all, and the exhaust leaks to the outside through the gap k between the valve shaft 12a and the exhaust pipe 20, so that it has the disadvantage of fouling the engine and the like, and it does not depend on the environment. There was still room for improvement in terms of sealability.

JP 08-31389 A JP 2008-274895 A

  An object of the present invention is to provide a shaft seal structure for an exhaust valve that is improved so that the sealing performance is clearly improved by further structural contrivance while the structure of the seal follows the labyrinth seal having many advantages. is there.

According to the first aspect of the present invention, a valve body 4 that opens and closes with respect to an internal flow path 3 of the valve case 1 is supported on a valve shaft 2 that is rotatably supported by the valve case 1. An exhaust valve shaft having a ring-shaped seal S fitted between the valve shaft 2 and a bearing portion 5 that supports the valve shaft 2 in the valve case 1 in order to exert a shaft sealing action on the flow path 3. In the sealed structure,
The ring-shaped seal S is composed of a laminate of a metal material 8a and an inorganic heat-resistant material 8b, and is a single ring plate 8 that is tightly fitted to the valve shaft 2 and loosely fitted to the bearing portion 5. Or a plurality of second ring plates 9 made of a laminate of a metal material 9a and an inorganic heat resistant material 9b, loosely fitted to the valve shaft 2 and tightly fitted to the bearing portion 5. Is configured by being alternately stacked in the direction of the axis P of the valve shaft 2,
A cross-sectional shape obtained by cutting the first and second ring plates 8 and 9 in the radial direction with respect to the axis P is set to a bent shape that is convex in the direction of the axis P of the valve shaft 2, and the ring shape. A tightening mechanism 10 for compressing the seal S in the axial center P direction is provided.

  The invention according to claim 2 is the exhaust valve shaft seal structure according to claim 1, wherein the first and second ring plates 8, 9 are one metal material 8a, 9a and one inorganic heat-resistant material. 8b and 9b, and the inorganic heat-resistant materials 8b and 9b are arranged in a state of being arranged on the mountain side in the convex bent shape.

  The invention according to claim 3 is the exhaust valve shaft sealing structure according to claim 1 or 2, wherein the first and second ring plates 8, 9 are directed toward the valve body 4 in the direction of the axis P. It is characterized by being aligned in a convex state.

  The invention according to claim 4 is the shaft seal structure for an exhaust valve according to any one of claims 1 to 3, wherein the inorganic heat-resistant materials 8b and 9b are made of mica.

  According to the invention of claim 1, although described in detail in the section of the embodiment, each ring plate made of a laminate of an inorganic heat-resistant material and a metal material becomes convex in the axial direction by compression by a tightening mechanism. Light press-fit with the first ring plate coming into contact with the valve shaft and the second ring plate coming into close contact with the bearing portion due to the radial expansion accompanying the forced deformation from the shape to the flat plate shape It becomes a joint state. In other words, the conventional labyrinth seal structure has been changed to a substantially contact-type seal structure, and since it has an inorganic heat-resistant material, the sliding performance with the valve shaft is increased, but the seal performance can be greatly improved while being assembled. It has excellent properties. As a result, it is possible to provide a shaft seal structure for an exhaust valve that is improved so as to clearly improve the sealing performance by further structural improvements while following the labyrinth seal having many advantages.

  According to the second aspect of the present invention, this will also be described in detail in the section of the embodiment. However, since the inorganic heat-resistant material, which is a relatively soft material, mainly comes into surface contact with the valve shaft, the valve shaft is rotated. Although the sliding torque generated when moving is only slightly increased, the sealing performance with respect to the valve shaft and the first ring plate is excellent, and as a result, the sealing performance is improved while suppressing an increase in sliding resistance. It is possible to provide a shaft seal structure for an exhaust valve that is improved so as to be clearly improved.

  According to the invention of claim 3, the ring plates adjacent in the axial direction are always in contact with each other through the inorganic heat-resistant material, as compared to the case where the ring plates adjacent in the axial direction protrude in opposite directions. As a result, the sealing performance between the ring plates is improved, and as a result, there is an advantage that the sealing performance is further improved. Moreover, as an inorganic heat-resistant material, the mica board which is lightweight and is easily available as mentioned in Claim 4 is mentioned.

Sectional view showing shaft seal structure for exhaust valve (Example 1) 1 shows the main part in the assembled state of FIG. 1, (a) is an enlarged view of the contact portion between the first ring plate and the valve shaft, and (b) is an enlarged view of the contact portion between the second ring plate and the bearing portion. Chart showing seal performance test conditions The figure which shows the characteristic graph of the gas seal Figure showing the characteristic graph of sliding torque Sectional view showing the schematic structure of a conventional exhaust valve Sectional view showing a conventional shaft seal structure for an exhaust valve

  Embodiments of an exhaust valve shaft sealing structure and an exhaust valve according to the present invention will be described below with reference to the drawings.

[Example 1]
In the exhaust valve shaft sealing structure, as shown in FIG. 1, a valve body 4 that opens and closes the internal flow path 3 of the valve case 1 is supported by a valve shaft 2 that is rotatably supported by the valve case 1. The exhaust valve V is provided and is fitted between the valve shaft 2 and the bearing portion 5 that supports the valve shaft 2 in the valve case 1 in order to exert a shaft sealing action on the internal flow path 3. A ring-shaped seal S is provided. The valve shaft 2 includes a split shaft type (see Patent Document 1) separated at a valve body part and a continuous single shaft type (see Patent Document 2), but either may be used in this embodiment. There is no limitation.

  The valve case 1 includes an inner flange 6 that is fitted in an internal flow path 3 that is an exhaust passage, a valve shaft 2 in a loosely fitted state, and receives a ring-shaped seal S in the direction of the axis P of the valve shaft 2, a valve A stainless steel bushing bearing 7 fitted on the shaft 2 and a bearing portion 5 having an inner peripheral surface 5a into which the ring-shaped seal S is fitted are formed. The valve shaft 2 is driven and rotated by an actuator (not shown) such as an electric motor so that the disc-like valve body 4 shown in a closed state in FIG. It has a publicly known structure that is rotated.

  The ring-shaped seal S is composed of a laminate of a ring-shaped stainless steel plate (an example of a metal material) 8a and a ring-shaped mica plate (an example of an inorganic heat-resistant material) 8b, and is closely fitted on the valve shaft 2 and is a bearing. Two of the first ring plate 8 that is loosely fitted in the part 5 (on the inner peripheral surface 5a), a ring-shaped stainless steel plate (an example of a metal material) 9a, and a ring-shaped mica plate (inorganic An example of a heat-resistant material) Two of the second ring plates 9 (a plurality of the plurality of second ring plates 9) that are laminated with the valve shaft 2 and are loosely fitted to the valve shaft 2 and tightly fitted to the bearing portion 5 (to the inner peripheral surface 5a). An example) is configured by being alternately stacked in the axis P direction of the valve shaft 2.

  In the free state, the cross-sectional shape cut in the radial direction of the first and second ring plates 8 and 9 is in the direction of the axis P, as depicted on the right side with respect to the axis P in FIG. It is set to a V-shaped bent shape that is convex toward the presence side of the body 4. Each of the first and second ring plates 8 and 9 is composed of one stainless steel plate 8a and 9a and one mica plate 8b and 9b, and the mica plates 8b and 9b are in the convex bent shape (the valve body in FIG. 1). (4 existing side) and arranged in a state of being arranged.

  Since the bending angles of the first and second ring plates 8 and 9 are equal to each other, the space portion a between the valve shaft 2 and the bearing portion 5 is simply loaded together with the bearing 7 (the axial center in FIG. 1). In the right side of P), the lower surface inner peripheral side portion of the mica plate 8b of each first ring plate 8 and the upper surface inner peripheral side end portion of the stainless plate 9a of each second ring plate 9 are in surface contact with each other, and bearings The lower surface outer peripheral side portion of the mica plate 9b in the seventh ring plate 9 on the 7 side and the upper surface outer peripheral side end portion of the stainless steel plate 8a in the first ring plate 8 directly below the surface contact each other.

  Then, the ring-shaped seal S is tightened in the direction of the axis P as shown on the left side of the axis P in FIG. In the compressed assembled state, the ring plates 8 and 9 are forcibly deformed into a flat plate posture, whereby the close fitting state between the first ring plate 8 and the valve shaft 2 is lightly press-fitted. The state is changed, and the close fitting state between the second ring plate 9 and the inner peripheral surface 5a is changed to the light press-fitted state.

  Although not shown in the drawings, the tightening mechanism 10 has, for example, a push-in cylinder portion that enters the space portion a and a flange portion that can be bolted to the valve case 1 and is loosely fitted to the valve shaft 2. There are known ones that bolt the compressed body (with a structure such as a mechanism for fastening the gland packing as shown in FIGS. 1 and 3 of JP-A-2002-349715). But it ’s okay.

  That is, in the assembled state, the first ring plate 8 and the valve shaft 2 that are in a close fitting state due to the radial expansion accompanying the forced deformation of the cross-sectional shape of the first ring plate 8 from the V shape to the flat plate shape. As shown in FIG. 2 (a), the radially inner end portion of the first ring plate 8 is bent and deformed toward the side opposite to the valve body 4 existence side. In addition, the mica plate 8b is greatly deformed and compressed so as to be adapted to the outer peripheral surface 2a of the valve shaft 2. This is due to forced deformation from a cross-sectional shape that protrudes toward the valve body 4 to a flat plate shape. That is, the mica plate 8b, which is mainly a relatively soft material, comes into surface contact with the valve shaft 2, so that the sliding torque generated when the valve shaft 2 is rotated can be slightly increased. The sealing performance related to the valve shaft 2 and the first ring plate 8 is excellent.

  Further, the second ring plate 9 and the inner peripheral surface 5a of the bearing portion 5 are also fitted, and for the same reason as in the case of the first ring plate 8 described above, as shown in FIG. The radially outer end of the second ring plate 9 is bent and deformed toward the side opposite to the valve body 4 side, and the mica plate 9b is greatly deformed and compressed so as to fit the inner peripheral surface 5a. It is deformed. Therefore, the mica plate 9b, which is mainly a relatively soft material, comes into surface contact with the inner peripheral surface 5a, and the sealing performance with respect to the second ring plate 9 and the bearing portion 5 is excellent.

  Since the first ring plate 8 and the second ring plate 9 are sealed by compression in the direction of the axis P, as a result, the ring-shaped seal S mainly has the mica plate 8b in contact with the valve shaft 2. It will function as a contact-type seal. That is, compared with the conventional labyrinth seal, the increase in the sliding torque of the festival for rotating the valve shaft 2 can be negligible, but the sealing performance is greatly improved so as to prevent leakage. Has become. Further, since the bearing 7 of the valve shaft 2 is disposed outside the ring-shaped seal S (on the side of the valve body 4 and downstream of the exhaust flow), the inner peripheral surface 6a of the inner flange 6 and the valve shaft 2 are arranged. Even if there is exhaust that passes through the gap between the ring 7 and the ring seal S, the exhaust is blocked (mostly reduced). There is also an advantage that the sliding resistance when the shaft 2 is rotated is increased (reduced).

  Each of the ring plates 8 and 9 which are constituent elements of the ring-shaped seal S is made of mica plates (heat-resistant inorganic materials) 8b and 9b having good slidability (low sliding resistance) and soft and familiar properties. Since it is affixed to and integrated with 8a and 9a, the shape retention of these mica plates 8b and 9b can be carried and the products (ring plates 8 and 9) can be moved and transported and assembled and disassembled. It has been realized. Further, each ring plate 8, 9 is formed in a bent shape that is convex in the direction of the axis P, such as a V-shaped cross section, so that it contacts the valve shaft 2 and the bearing portion 5 in the assembled state. However, in the free state, the radial dimension is slightly reduced, and therefore, there is an advantage that the operability of the loading operation is excellent due to excellent insertability into the space portion a during assembly.

  For reference, FIG. 4 shows an exhaust (gas seal) characteristic graph of the ring-shaped seals 1 and 2 and a conventional product, and a sliding torque characteristic graph with the valve shaft 2. As shown in FIG. 3 (a), the test conditions are as follows. Nitrogen of 0.4 MPa at room temperature is used as the fluid, and as shown in FIG. The rotation over 90 degrees between the open position and the closed position is reciprocated 50,000 times at 0.01 m / s. 4 and 5, n1 and n2 mean the exhaust valve shaft sealing structure 1 and 2 according to the present invention (n number = 2).

  As shown in FIG. 4, the gas seal characteristics of the present invention structures n1 and n2, which are substantially contact-type seal structures, regardless of the number of sliding operations, are units compared to the conventional structure of the labyrinth seal structure. It can be understood that the amount of leakage per hour is overwhelmingly advantageous with an order of magnitude less. Further, as shown in FIG. 5, the sliding characteristics of the present invention structures n1 and n2 are about 0.1 N · as the number of sliding increases as compared to the conventional structure where no sliding torque is generated. It can be understood that it converges to m. This sliding torque of 0.1 N · m does not cause any particular problems in practice, and therefore, the sealing performance can be greatly improved while the sliding characteristics are suppressed to a level where there is no problem.

[Another Example]
The cross-sectional shapes of the first and second ring plates 8 and 9 may be U-shaped, W-shaped, or other shapes, and may be any shape that is convex in the direction of the axis P.

DESCRIPTION OF SYMBOLS 1 Valve case 2 Valve shaft 3 Internal flow path 4 Valve body 5 Bearing part 8 1st ring plate 8a Metal material 8b Inorganic heat resistant material, mica 9 2nd ring plate 9a Metal material 9b Inorganic heat resistant material, mica 10 Tightening mechanism P axis Heart S ring seal

Claims (4)

A valve body that opens and closes with respect to the internal flow path of the valve case is supported on a valve shaft that is rotatably supported by the valve case, and in order to exert a shaft sealing action on the internal flow path, the valve A shaft seal structure for an exhaust valve having a ring-shaped seal fitted between a bearing portion that supports the valve shaft in the case and the valve shaft,
The ring-shaped seal is made of a laminate of a metal material and an inorganic heat-resistant material, and the metal material is a single or a plurality of first ring plates that are tightly fitted to the valve shaft and are loosely fitted to the bearing portion. And a plurality of second ring plates that are loosely fitted to the valve shaft and tightly fitted to the bearing portion are alternately arranged in the axial direction of the valve shaft. It is composed of being deployed in layers,
A cross-sectional shape obtained by cutting the first and second ring plates in a radial direction with respect to the shaft center is set to a bent shape that is convex in the shaft center direction of the valve shaft, and the ring-shaped seal is moved in the shaft center direction. A shaft seal structure for an exhaust valve equipped with a tightening mechanism for compression.   The said 1st and 2nd ring board consists of one said metal material and one said inorganic heat resistant material, The said inorganic heat resistant material is comprised in the state arrange | positioned at the peak side in a convex bending shape. The shaft seal structure for an exhaust valve as described.   The shaft sealing structure for an exhaust valve according to claim 1 or 2, wherein the first and second ring plates are aligned so as to protrude toward the valve body in the axial direction.   The shaft seal structure for an exhaust valve according to any one of claims 1 to 3, wherein the inorganic heat resistant material is made of mica.

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