KR20230036985A - Seat part structure - Google Patents

Abstract

Provided is a seat part structure, which can prevent reduction in visibility by a gasket between a cylinder cover and an exhaust valve sheet. The seat part structure bonds the cylinder cover of a cylinder having a combustion chamber of a diesel engine for a ship to the exhaust valve sheet, which seats an exhaust valve opening and closing an exhaust port of the combustion chamber, by inserting a ring-shaped gasket therebetween. The cylinder cover comprises: a sheet portion which is formed in a ring shape to cover a lengthwise axis of the cylinder and has an external diameter greater than that of the gasket, and in which the gasket is disposed; and a latching portion which is formed along an inner circumferential end portion of the sheet portion and comes in contact with an inner circumferential surface of the gasket disposed in the sheet portion to latch the gasket. The exhaust valve sheet is formed in a ring shape to insert the gasket therebetween and face the sheet portion, and is provided with a sheet portion of the valve sheet having an external diameter greater than the external diameter of the gasket.

Description

Seat part structure {SEAT PART STRUCTURE}

The present invention relates to a seat structure for airtightly bonding a cylinder cover and an exhaust valve seat of a marine diesel engine.

In a marine diesel engine mounted on a ship, conventionally, in order to prevent gas leakage from a combustion chamber, a sealing member is sandwiched between parts such as a cylinder facing the combustion chamber, and the gap at the junction is sealed. are doing For example, a cylinder cover, which is one component of a cylinder, and an exhaust valve seat on which an exhaust valve that opens and closes an exhaust port of a combustion chamber are seated are joined by sandwiching a gasket, which is an example of a sealing member.

In general, an exhaust valve box for supporting the exhaust valve to slide freely is mounted on an upper portion of the exhaust valve seat. The exhaust valve box is fixed to the top of the cylinder cover by tightening bolts with the exhaust valve seat sandwiched between the cylinder cover and the cylinder cover. Further, a gasket is placed on the seat of the cylinder cover, and the gasket is sandwiched between the seat of the cylinder cover and the seat of the exhaust valve seat, so that the exhaust valve seat is bonded to the top of the cylinder cover. In this way, the cylinder cover and the exhaust valve seat in a state where the gasket is sandwiched between the seat portions are fixed together with the exhaust valve box by the fastening force of the bolt. The seat portion referred to here is a joint portion between components sealed by sandwiching a gasket therebetween.

Further, Patent Literature 1 discloses a structure in which a lower surface of a cylinder cover and an upper surface of a cylinder liner are joined together with a gasket interposed therebetween. In the bonding structure disclosed in Patent Literature 1, a circumferential groove is formed on the upper surface of the cylinder liner to relieve local stress at the edge portion of the gasket. Further, Patent Literature 2 discloses a structure in which a cylinder cover and an exhaust valve seat (valve seat ring) are joined via a build-up layer by laser metal build-up.

Japanese Unexamined Patent Publication No. 2014-126023 Japanese Unexamined Patent Publication No. 2020-51335

However, in the conventional seat structure for joining the cylinder cover and the exhaust valve seat with a gasket interposed therebetween, the gasket placed on the seat portion of the cylinder cover is used during bonding work or combustion of the cylinder cover and the exhaust valve seat. When pressure in the cylinder is received from the actual side, there is a case where the position is biased to one side (inside or outside the cylinder) of the seat portion. In this case, the gasket is deformed along the shape of the gap between the cylinder cover and the exhaust valve seat (for example, curved shape), and as a result, the sealing performance of the gasket between the seat portions is lowered and gas leaks from the combustion chamber. There is a possibility that this may occur.

In addition, since the combustion chamber is in a high temperature state during operation of the marine diesel engine, the cylinder cover and the exhaust valve seat expand and deform due to the high heat transmitted from the combustion chamber, and the gasket between these seats also expands accordingly. may be deformed. Such expansion and deformation of the gasket is strongly suppressed as the portion closer to the bolt described above, but is more difficult to suppress as the portion farther from the bolt, so it tends to be distorted deformation (e.g., deformation from circular shape to elliptical shape). . Also in this case, the sealing property between the seat portions by the gasket is deteriorated, and gas leakage from the combustion chamber may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a seat portion structure capable of suppressing deterioration in sealing performance due to a gasket between the seat portion of a cylinder cover and an exhaust valve seat.

In order to solve the above problems and achieve the objects, a seat structure related to the present invention is a cylinder cover of a cylinder having a combustion chamber of a marine diesel engine, and an exhaust valve for seating an exhaust valve that opens and closes an exhaust port of the combustion chamber. A seat portion structure for joining a seat by interposing an annular gasket surrounding a longitudinal axis of the cylinder, wherein the cylinder cover is formed annularly so as to surround the longitudinal axis of the cylinder, and the outer diameter of the gasket is The gasket has a larger outer diameter and is formed along a cylinder cover seat portion on which the gasket is placed and an inner circumferential end of the cylinder cover seat portion, and is in contact with an inner circumferential surface of the gasket placed on the cylinder cover seat portion. The exhaust valve seat is formed in an annular shape so as to face the cylinder cover seat portion with the gasket interposed therebetween, and has a valve seat seat portion having an outer diameter larger than the outer diameter of the gasket, characterized by

Further, the seat portion structure according to the present invention is characterized in that, in the above invention, the engaging portion is formed in a convex shape projecting toward the valve seat seat portion rather than the cylinder cover seat portion.

Further, the seat structure according to the present invention is characterized in that, in the above invention, the locking portion is formed in an annular or arcuate shape along the inner circumferential end of the cylinder cover seat portion.

Further, the seat structure according to the present invention is characterized in that, in the above invention, the cylinder cover further includes a groove portion along an outer circumferential end of the locking portion.

ADVANTAGE OF THE INVENTION According to this invention, the effect that the sealing property deterioration by the gasket between a cylinder cover and the seat part of an exhaust valve seat can be suppressed is exhibited.

1 is a schematic diagram showing an example of a configuration of the vicinity of a seat portion structure of a marine diesel engine according to an embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view showing one configuration example of a seat structure according to an embodiment of the present invention.
Fig. 3 is an enlarged cross-sectional schematic diagram showing a main part of a seat structure according to an embodiment of the present invention in an enlarged manner.
Fig. 4 is a schematic cross-sectional view along the line AA of the seat structure shown in Fig. 2;
Fig. 5 is a schematic diagram for explaining the action of the locking portion of the seat structure according to the embodiment of the present invention.
Fig. 6 is a schematic view for explaining the action of the cylinder cover seat portion and the valve seat seat portion of the seat portion structure according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the accompanying drawings, preferred embodiments of the seat portion structure according to the present invention will be described in detail. In addition, this invention is not limited by this embodiment. In addition, it is necessary to note that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, and the like may differ from those in reality. Even between the drawings, there are cases where there are parts in which the relationship or ratio of dimensions to each other is different. Moreover, in each drawing, the same code|symbol is attached|subjected to the same component part.

(Configuration of marine diesel engine)

First, the configuration of a marine diesel engine having a cylinder cover and an exhaust valve seat to which the seat portion structure related to the embodiment of the present invention is applied will be described. In an embodiment of the present invention, the seat portion structure surrounds a cylinder cover of a cylinder having a combustion chamber of a marine diesel engine and an exhaust valve seat on which an exhaust valve for opening and closing an exhaust port of the combustion chamber is seated, around the longitudinal axis of the cylinder. It is a bonding structure for joining an annular gasket by sandwiching it therebetween.

1 is a schematic diagram showing an example of a configuration of the vicinity of a seat portion structure of a marine diesel engine according to an embodiment of the present invention. The marine diesel engine 1 shown in FIG. 1 is a propulsion engine (main engine) that rotates a propeller (not shown) for propulsion of a ship via a propeller shaft. For example, the marine diesel engine 1 is a two-stroke diesel engine such as a known uniflow small exhaust type crosshead type diesel engine. Although a 6-cylinder engine etc. are mentioned as the marine diesel engine 1, the number of cylinders is not specifically limited. Moreover, although a cam type or electronic control type etc. are mentioned as an operation control system of the marine diesel engine 1, it is not specifically limited.

In addition, the structure of the seat part structure vicinity of the marine diesel engine 1 is the same also in any cylinder (cylinder). For this reason, below, the structure around the seat part structure of the marine diesel engine 1 is demonstrated about one cylinder among them.

As shown in FIG. 1, the marine diesel engine 1 includes a cylinder liner 2, a cylinder cover 3, a piston 5, an exhaust valve 6, an exhaust valve seat 7, It is constituted by including an exhaust valve box 9 and an upper valve actuating device 11.

The cylinder liner 2 is a cylindrical structure, and a cylinder cover 3 is attached to the top of the cylinder liner 2 . These cylinder liner 2 and cylinder cover 3 constitute one cylinder 4 in the marine diesel engine 1, and a normal space in which the piston 5 reciprocates (that is, the cylinder 4 ) is forming a space within). The piston 5 is installed so that it can reciprocate freely in this space. Although not particularly shown, a piston rod is connected to the lower portion of the piston 5, and the lower portion of the piston rod is connected to the crankshaft via a crosshead or the like. This crankshaft rotates in response to the reciprocating motion of the piston 5, thereby rotating the propeller shaft and the like.

Moreover, as shown in FIG. 1, the exhaust valve 6 is equipped with the valve body 6a and the valve rod 6b. The exhaust valve seat 7 is formed in an annular shape so as to have a seating surface on which the valve element 6a of the exhaust valve 6 can be seated over its entire circumference, and has an exhaust port 7a leading to the exhaust port of the combustion chamber 8. form inside As shown in FIG. 1 , the exhaust valve seat 7 is attached to the top of the cylinder cover 3 . The combustion chamber 8 which the cylinder 4 has inside is formed by these cylinder liner 2, cylinder cover 3, piston 5, and valve body 6a. Inside the combustion chamber 8, fuel (fossil fuel such as heavy oil or light oil or alternative fuel such as hydrogen) or fuel other than water is supplied from a fuel injection valve (not shown) attached to the cylinder cover 3. of liquid is sprayed.

As shown in FIG. 1 , the exhaust valve box 9 is attached to the top of the cylinder 4 in a state where the exhaust valve seat 7 is sandwiched between the cylinder cover 3 and the cylinder cover 3 . In the present embodiment, the exhaust valve box 9 includes a plurality of (two in FIG. 1) bolts 13a positioned at predetermined intervals in the circumferential direction of the longitudinal axis 4a of the cylinder 4, for example. , 13b), it is fixed to the upper part of the cylinder cover 3. Accordingly, the lower end of the exhaust valve box 9 is connected to the upper end of the exhaust valve seat 7 mounted on the top of the cylinder cover 3. At the same time, the cylinder cover 3 and the exhaust valve seat 7 are joined and fixed by the tightening force of the bolts 13a and 13b in a state where the gasket 15 is sandwiched between the seat portions of each other. In addition, the longitudinal axis 4a of the cylinder 4 is the central axis of the longitudinal direction of the cylinder 4. Further, the exhaust valve box 9 supports the exhaust port 9a communicating with the exhaust port 7a of the exhaust valve seat 7 and the valve stem 6b of the exhaust valve 6 so as to slide freely. It has a valve rod guide 10 inside.

The upper valve actuating device 11 is attached to the upper part of the exhaust valve box 9, and is configured such that the exhaust valve 6 can be reciprocally moved. The upper valve actuating device 11 includes an elastic support member (not shown) such as a compression spring or an air spring therein, and by the action of this elastic support member, the exhaust valve 6 is moved to the exhaust port 7a. ) is supported in a state in which it is elastically supported in the direction of closing (opening). Further, the upper valve operating device 11 lowers the exhaust valve 6 against the elastic support member with the hydraulic pressure of the hydraulic oil supplied from the fuel supply pump (not shown) through the pipe. In this way, the upper valve operating device 11 operates the exhaust valve 6 to open the exhaust port 7a. The exhaust valve 6 opens the exhaust port 7a only while hydraulic oil is being supplied to the upper valve operating device 11, and closes the exhaust port 7a when the supply of this hydraulic oil is stopped.

In such a marine diesel engine 1, after combustion gas such as air is introduced into the combustion chamber 8 from a scavenging port (not shown), the piston 5 rises, and the exhaust valve 6 removes the gas from the exhaust port. When 7a is closed, the combustion gas in the combustion chamber 8 is compressed. In the combustion chamber 8, the compressed combustion gas and injection liquid such as fuel injected from the fuel injection valve mix and burn, and the piston 5 moves down due to combustion energy. Exhaust gas in the combustion chamber 8 passes through the exhaust port 7a to the exhaust port in the exhaust valve box 9 at the timing when the exhaust valve 6 opens the exhaust port 7a of the exhaust valve seat 7. (9a) is discharged. After that, the exhaust gas is discharged from the exhaust port 9a through a pipe to an exhaust manifold (not shown).

(Seat structure)

Next, the seat portion structure according to the embodiment of the present invention will be described. The seat portion structure according to this embodiment is a joining structure for joining the cylinder cover 3 and the exhaust valve seat 7 described above with a gasket 15 interposed therebetween. Fig. 2 is a cross-sectional schematic diagram showing one configuration example of a seat structure according to an embodiment of the present invention. Fig. 3 is an enlarged cross-sectional schematic diagram showing a main part of a seat structure according to an embodiment of the present invention in an enlarged manner. In addition, in FIG. 3, the part enclosed by the broken line in FIG. 2 is shown enlarged. Fig. 4 is a schematic cross-sectional view along the line A-A of the seat structure shown in Fig. 2;

In the seat portion structure according to the present embodiment, as shown in FIGS. 2 to 4 , the cylinder cover 3 is a cylinder cover joined to the seat portion of the exhaust valve seat 7 with a gasket 15 interposed therebetween. A seat portion 31 and a locking portion 32 for holding the gasket 15 are provided.

As shown in FIGS. 3 and 4 , the cylinder cover seat portion 31 is a joint surface joined to the valve seat portion 71 of the exhaust valve seat 7 with the gasket 15 interposed therebetween, and the cylinder ( 4) is formed annularly so as to surround the longitudinal axis 4a of (see Fig. 1). For example, as shown in FIG. 4 , the cylinder cover sheet portion 31 is preferably an annular surface in a top view viewed from above in the direction of the longitudinal axis 4a. Further, as shown in FIG. 3 , the cylinder cover sheet portion 31 has an outer diameter R2 larger than the outer diameter R1 of the annular gasket 15 . On such a cylinder cover sheet part 31, as shown in FIGS. 3 and 4, the gasket 15 is mounted.

In addition, the inner diameter of the cylinder cover seat portion 31 is such that the gasket 15 can be mounted on the cylinder cover seat portion 31, and the cylinder cover 3 and the exhaust valve seat 7 are separated by the gasket 15. The inner diameter of the gasket 15 may be larger, smaller, or the same as the inner diameter of the gasket 15, as long as the sealing between the seat portions is possible. Further, the width of the cylinder cover seat portion 31 is the distance between the inner peripheral end portion 31a and the outer peripheral portion 31c, and, for example, the joint strength and seal between the gasket 15 and the cylinder cover seat portion 31 It is set to secure a bonding area suitable for sex.

The locking portion 32 is for positioning the gasket 15 placed on the cylinder cover seat portion 31 and suppressing displacement of the gasket 15 after placement. In detail, as shown in FIGS. 3 and 4 , the locking portion 32 is formed in an annular or arcuate shape along the inner peripheral end portion 31a of the cylinder cover seat portion 31 . For example, the locking portion 32 is located closer to the inner circumference of the cylinder cover 3 than the cylinder cover seat 31, and continues in an annular shape over the entire inner circumference of the cylinder cover seat 31. is formed

Further, as shown in FIGS. 3 and 4 , the locking portion 32 is formed in a convex shape projecting toward the valve seat portion 71 side of the exhaust valve seat 7 from the cylinder cover seat portion 31, It has a side wall surface (32a) extending from the cover seat portion (31) side to the valve seat seat portion (71) side. The side wall surface 32a of the locking portion 32 faces the inner circumferential surface 15a of the gasket 15 on the cylinder cover seat portion 31 in the radial direction of the cylinder cover 3 . For example, when the hooking portion 32 is formed in an annular or arc shape along the inner peripheral end portion 31a of the cylinder cover seat portion 31, the side wall surface 32a of the hooking portion 32 has an outer circumferential surface of the annular or arc shape. am. In particular, when the locking portion 32 forms an annular shape that extends over the entire inner circumference of the cylinder cover seat portion 31, the side wall surface 32a of the locking portion 32 extends over the entire circumference of the annular shape. It is the outer periphery that continues throughout. In addition, the radial direction of the cylinder cover 3 is a direction perpendicular to the longitudinal axis 4a of the cylinder 4 . The locking portion 32 brings the inner circumferential surface 15a of the gasket 15 mounted on the cylinder cover seat portion 31 into contact with its own side wall surface 32a, and engages the gasket 15 therein.

Such a locking portion 32 comes into contact with the inner circumferential surface 15a of the gasket 15 placed on the cylinder cover sheet portion 31 and engages the gasket 15, thereby locking the cylinder cover sheet portion 31 on the cylinder cover sheet portion 31. The placement of the gasket 15 is determined. Further, the locking portion 32 suppresses displacement of the gasket 15 sandwiched between the cylinder cover seat portion 31 and the valve seat seat portion 71 by the gasket 15 being caught. .

Further, from the viewpoint of fastening the gasket 15 by the locking portion 32, the locking portion 32 is preferably formed in the above-mentioned annular shape, but the inner circumferential end portion 31a of the cylinder cover sheet portion 31 It may be formed as an intermittent arc along In this case, from the viewpoint that the gasket 15 can be reliably hooked at any part of the inner circumferential surface 15a by the hooking part 32, the arc-shaped hooking part 32 has the longitudinal axis 4a of the cylinder 4 ) is preferably formed at equal intervals in the axis circumferential direction of

Moreover, as shown in FIGS. 3 and 4 , the cylinder cover 3 is provided with a groove portion 33 along the outer peripheral end of the engaging portion 32 . The groove portion 33 is a groove for facilitating the formation of the locking portion 32 described above on the inner peripheral side of the cylinder cover seat portion 31 . In detail, in the structure of the seat portion of the cylinder cover 3 and the exhaust valve seat 7, for example, the junction of the cylinder cover 3 joined to the exhaust valve seat 7 via the gasket 15 By performing processing such as grinding the surface, the cylinder cover seat portion 31 is formed, and the locking portion 32 projecting beyond the cylinder cover seat portion 31 is formed. At this time, the side wall surface 32a of the hooking part 32 is an inclined surface (preferably the diameter of the cylinder cover sheet part 31) that goes down steeply from the hooking part 32 side toward the cylinder cover seat part 31 side. vertical plane orthogonal to the direction). Such a side wall surface 32a can be formed simply by scraping the outer circumferential surface of the engaging portion 32 so that the groove portion 33 is formed along the outer circumferential end of the engaging portion 32 . That is, formation of the groove portion 33 enables simple formation of the side wall surface 32a of the locking portion 32 opposing the inner circumferential surface 15a of the gasket 15 described above.

On the other hand, the exhaust valve seat 7 seats the valve body 6a of the exhaust valve 6 that opens and closes the exhaust port of the combustion chamber 8, as described above. Such an exhaust valve seat 7 is bonded to the seat portion of the cylinder cover 3 with a gasket 15 interposed therebetween, as shown in FIGS. 2 and 3 in the seat portion structure according to the present embodiment. A valve seat seat portion 71 is provided.

As shown in FIG. 3 , the valve seat seat portion 71 is a joint surface joined to the cylinder cover seat portion 31 with the gasket 15 interposed therebetween, and the longitudinal axis 4a of the cylinder 4 is It is formed in an annular shape so as to surround it. That is, the valve seat seat portion 71 is formed in an annular shape so as to face the cylinder cover seat portion 31 with the gasket 15 interposed therebetween. For example, the valve seat seat portion 71 is preferably an annular surface when viewed from the lower side in the direction of the longitudinal axis 4a. Further, as shown in Fig. 3, the valve seat seat portion 71 has an outer diameter R3 larger than the outer diameter R1 of the annular gasket 15.

In addition, the inner diameter of the valve seat seat portion 71 is not particularly limited as long as the cylinder cover seat portion 31 and the valve seat seat portion 71 can be joined with the gasket 15 therebetween, but, for example, It is set smaller than the inner diameter of the cylinder cover seat part 31. In addition, the width of the valve seat seat portion 71 is the distance between the inner circumferential end and the outer circumferential end 71c, for example, a joint suitable for bonding strength and sealability between the gasket 15 and the valve seat seat portion 71. It is set to secure the area. For example, as shown in FIG. 3 , the width of the valve seat portion 71 is the width of the annular region extending from the outer peripheral end 31c of the cylinder cover seat portion 31 to the inner peripheral end of the engaging portion 32. It may be set above.

Further, as shown in FIG. 2 , the gasket 15 is a sealing member sandwiched between the cylinder cover 3 and the seat portion of the exhaust valve seat 7 joined to each other. In detail, the gasket 15 is, for example, a sealing member made of a material such as metal, and as shown in Figs. For example, it is formed in an annular shape). The gasket 15 is placed on the cylinder cover seat portion 31 so as to be positioned on the outer circumferential side of the locking portion 32 in the cylinder cover 3 . In this placed state, the inner circumferential surface 15a of the gasket 15 faces the side wall surface 32a on the outer circumferential side of the engaging portion 32 . Such a gasket 15, by bringing its inner circumferential surface 15a and the side wall surface 32a of the locking portion 32 into contact with each other, the displacement in the radial direction on the cylinder cover seat portion 31 is restricted and positioned. It is decided. 3 and 4, the state before the inner circumferential surface 15a of the gasket 15 and the side wall surface 32a of the engaging portion 32 come into contact, that is, the gasket on the cylinder cover seat portion 31 ( 15) is shown before limiting the displacement and determining the position.

The gasket 15 mounted on the cylinder cover seat 31 in this way is formed between the cylinder cover seat 31 and the valve seat seat 71 by the tightening force of the bolts 13a and 13b described above. plugged into Accordingly, the gasket 15 airtightly seals the space between the cylinder cover seat 31 and the valve seat seat 71.

(action of seat structure)

Next, the function of the seat structure of the cylinder cover 3 and the exhaust valve seat 7 in the embodiment of the present invention will be described. As an example of the action of the seat structure, first, the action of the locking portion 32 of the cylinder cover 3 on the gasket 15 will be described.

Fig. 5 is a schematic diagram for explaining the action of the locking portion of the seat structure according to the embodiment of the present invention. The cylinder cover 3 and the exhaust valve seat 7 are joined with a gasket 15 interposed between the cylinder cover seat 31 and the valve seat seat 71. In the seat structure of the cylinder cover 3 and the exhaust valve seat 7, the gasket 15, as shown in FIG. ) and the valve seat seat portion 71. The inner circumferential surface 15a of this gasket 15 faces the side wall surface 32a of the engaging portion 32 (the outer circumferential surface of the engaging portion 32 in this embodiment).

Between the cylinder cover 3 and the exhaust valve seat 7 bonded to each other with the gasket 15 interposed therebetween, the above-described combustion chamber 8 and the inner circumferential surface 15a of the gasket 15 communicate. Gaps are generated (see Figs. 2 and 3). For example, as indicated by a bold line arrow in FIG. 5 , the pressure in the combustion chamber 8 (pressure in the cylinder) passes through the gap 16 between the cylinder cover 3 and the exhaust valve seat 7, and the gasket It may be applied to the inner circumferential surface 15a of (15). In this case, the inner circumferential surface 15a of the gasket 15 is pressed to the outer circumferential side by the above cylinder pressure, and as a result, the entire gasket 15 together with the portion of the inner circumferential surface 15a that has received this cylinder pressure Displacement is intended to be excessively biased to one side of the seat portion 31 (the right side of the sheet in FIG. 5). In addition, the excessively biased displacement of the gasket 15 means that the outer circumferential end of either part of the annular gasket 15 is displaced to the outer circumferential side than the outer circumferential end 31c of the cylinder cover sheet portion 31. .

However, in the seat portion structure according to the present embodiment, as shown in FIG. 5 , the inner circumferential surface 15a of the gasket 15 is in a state facing the side wall surface 32a of the engaging portion 32 . For this reason, even if the gasket 15 is excessively displaced to one side of the cylinder cover seat portion 31 as described above, the longitudinal axis 4a of the cylinder 4 ( As shown in FIG. 5 , the inner circumferential surface 15a of the gasket 15 on the opposite side with the gasket 15 interposed therebetween (see FIGS. 1 and 2) comes into contact with the side wall surface 32a of the locking portion 32 and is caught. Accordingly, the entire gasket 15 is engaged by the locking portion 32 together with the inner circumferential surface 15a on the opposite side, and as a result, the entire displacement of the gasket 15 is restricted by the locking portion 32. Therefore, it is possible to avoid a situation in which the gasket 15 is excessively biased to one side of the cylinder cover sheet portion 31 and is displaced (displaced).

Further, in the seat portion structure according to the present embodiment, the gasket 15 is secured to the cylinder cover seat portion by the action of the locking portion 32 on the gasket, similarly to the case of preventing displacement of the gasket due to the pressure in the cylinder. When placed on the 31, the position of the gasket 15 on the cylinder cover seat 31 in the radial direction can be limited, and the gasket 15 can be positioned.

Next, as an example of the action of the seat structure according to the embodiment of the present invention, the action of the cylinder cover seat 31 and the valve seat seat 71 on the gasket 15 will be described. Fig. 6 is a schematic view for explaining the action of the cylinder cover seat portion and the valve seat seat portion of the seat portion structure according to the embodiment of the present invention.

In the seat portion structure for joining the cylinder cover 3 and the exhaust valve seat 7 with the gasket 15 interposed therebetween, as described above, the outer diameter R2 of the cylinder cover seat portion 31 and the valve The outer diameter R3 of the sheet seat portion 71 is larger than the outer diameter R1 of the gasket 15 in both cases (see Fig. 3). That is, as shown in FIG. 3 , the cylinder cover seat portion 31 has an outer peripheral portion 31b located on the outer peripheral side of the outer peripheral end of the gasket 15 . The valve seat seat portion 71 has an outer circumferential portion 71b located on the outer circumferential side of the outer circumferential end of the gasket 15 . 3 illustrates a case where the outer diameter R3 of the valve seat seat portion 71 is larger than the outer diameter R2 of the cylinder cover seat portion 31, the present invention is not limited to this. . That is, the outer diameter R2 of the cylinder cover seat 31 may be larger, smaller, or the same as the outer diameter R3 of the valve seat seat 71 .

The outer peripheral portions 31b and 71b of the cylinder cover seat portion 31 and the valve seat seat portion 71 are secured by bolts for fixing the cylinder cover 3 and the exhaust valve box 9 together with the exhaust valve seat 7 ( By the fastening force of 13a and 13b) (refer to FIG. 1), they are bent and deformed in directions closer to each other.

In detail, as shown in FIG. 6, the outer periphery 31b of the cylinder cover seat 31 is located below the outer periphery 71b of the valve seat seat 71, and the bolts 13a, 13b By the tightening force, it is bent and deformed to form an inclined surface that rises gently from the outer peripheral end side of the gasket 15 toward the outer peripheral end 31c side of the cylinder cover seat portion 31. The outer circumferential portion 71b of the valve seat seat portion 71 is located above the outer circumferential portion 31b of the cylinder cover seat portion 31, and the outer circumferential end of the gasket 15 It is bent and deformed to form an inclined surface that gently descends from the side toward the outer circumferential end 71c side of the valve seat seat portion 71. As a result, the cylinder cover seat portion 31 and the valve seat seat portion 71 have a distance L between the outer peripheral ends 31c and 71c compared to the state before each deformation (see the broken line portion in FIG. 6). narrow it down As a result, the distance L between the outer circumferential end 31c of the cylinder cover seat 31 and the outer circumferential end 71c of the valve seat seat 71 is It is smaller than the thickness H of the gasket 15 interposed between the 71 (hereinafter, abbreviated as the gasket 15 between seat portions as appropriate).

The degree of bending deformation of the outer peripheral portions 31b and 71b of the cylinder cover seat 31 and the valve seat seat 71 described above varies depending on the distance from the bolts 13a, 13b. However, the distance L between the outer circumferential ends 31c and 71c of the cylinder cover seat portion 31 and the valve seat portion 71 is, even if there is a difference in the degree of the bending deformation, the cylinder cover seat portion 31 ) and the entire circumference of the valve seat seat portion 71, is smaller than the thickness H of the gasket 15 between the seat portions.

Here, the cylinder cover 3 and the exhaust valve seat 7 expand and deform due to the high heat transmitted from the high-temperature combustion chamber 8 during operation of the marine diesel engine 1 . Accompanying this, the gasket 15 between the seat portions may expand and deform due to the high heat. In this case, the expansion and deformation of the gasket 15 is strongly suppressed by the fastening force at the site closer to the bolts 13a and 13b, but the more difficult it is at the site farther from the bolts 13a and 13b. Therefore, the gasket 15 between the seat portions tends to expand and deform distortedly, as exemplified by the deformation from circular to elliptical.

In contrast, in the seat structure according to the present embodiment, as shown in FIG. 6 , the outer peripheral portions 31b and 71b of the cylinder cover seat 31 and the valve seat seat 71 extend along their entire circumferences. , bending deformation is performed so that the distance L between the outer circumferential ends 31c and 71c is smaller than the thickness H of the gasket 15 between the seat portions. The cylinder cover seat portion 31 and the valve seat seat portion 71 in which the respective outer peripheral portions 31b and 71b are bent and deformed in this way are uniformly spread over the entire circumference of the gasket 15 between the seat portions toward the outer circumferential side. and thus, distorted expansion deformation of the gasket 15 is prevented.

As described above, in the seat structure according to the embodiment of the present invention, the cylinder cover 3 of the cylinder 4 having the combustion chamber 8 of the marine diesel engine 1 is provided with the longitudinal axis of the cylinder 4. cylinder cover sheet portion 31 which is annularly formed so as to surround 4a and has an outer diameter R2 larger than the outer diameter R1 of gasket 15, and an inner circumferential end portion 31a of cylinder cover sheet portion 31 An exhaust valve seat 7 on which an exhaust valve 6 for opening and closing the exhaust port of the combustion chamber 8 is seated forms a hooking portion 32 disposed along the cylinder cover seat portion 31 and annularly opposed to the cylinder cover seat portion 31. An annular gasket 15 surrounding the longitudinal axis 4a of the cylinder 4 and forming a valve seat seat portion 71 formed and having an outer diameter R3 larger than the outer diameter R1 of the gasket 15 between the cylinder cover seat 31 and the valve seat seat 71 to bond the cylinder cover 3 and the exhaust valve seat 7, and the gasket 15 mounted on the cylinder cover seat 31 The gasket 15 is engaged by the locking portion 32 in contact with the inner circumferential surface 15a.

For this reason, while positioning of the gasket 15 at the time of placing the gasket 15 on the cylinder cover seat portion 31 can be performed by the locking portion 32, for example, the gasket 15 between the seat portions ), even when pressure is applied to the inner circumferential surface 15a, the gasket 15 is excessively biased to one side of the cylinder cover seat portion 31 and the position is displaced. Furthermore, the cylinder cover seat portion 31 and the valve seat seat portion ( 71), the outer peripheral portions 31b and 71b are bent and deformed so that the distance L between the outer peripheral ends 31c and 71c can be reduced to less than the thickness H of the gasket 15 between the seat portions. As a result, since expansion and deformation of the gasket 15 due to high heat can be suppressed over the entire circumference of the cylinder cover seat portion 31 and the valve seat seat portion 71, distorted expansion of the gasket 15 is prevented. deformation can be prevented. From the above, since the sealing property by the gasket 15 between the cylinder cover seat portion 31 and the valve seat seat portion 71 is improved, the gap between the cylinder cover 3 and the seat portion of the exhaust valve seat 7 is improved. Deterioration of sealability due to the gasket 15 can be suppressed, and as a result, gas leakage from the combustion chamber 8 through the gap between the cylinder cover 3 and the exhaust valve seat 7 can be prevented.

Further, in the above-described embodiment, an annular or arc-shaped locking portion 32 is formed on the inner circumferential side of the seat portion of the cylinder cover 3, but the present invention is not limited to this. For example, the locking portion 32 may be constituted by a plurality of pins attached to the cylinder cover 3 along the inner circumferential end portion 31a of the cylinder cover seat portion 31 or a convex member such as a frame body. In this case, the above-mentioned groove part 33 does not need to be formed on the outer peripheral side of the engaging part 32.

Further, in the above-described embodiment, the respective outer peripheral portions 31b and 71b of the cylinder cover seat portion 31 and the valve seat seat portion 71 are bent and deformed, but in the present invention, the respective outer peripheral portions 31b and 71b ) may be elastic deformation or plastic deformation.

In addition, in the embodiment described above, the exhaust valve box 9 and the cylinder cover 3 are fixed together with the exhaust valve seat 7 by two bolts 13a and 13b, but in the present invention, these The number of bolts for fixing is not particularly limited. For example, the number of bolts may be one or two or more.

In addition, this invention is not limited by the embodiment mentioned above, What was comprised by combining each component mentioned above suitably is also included in this invention. In addition, all other embodiments, examples, operation techniques, etc. made by those skilled in the art based on the above-described embodiment are all included in the scope of the present invention.

1: marine diesel engine
2 : cylinder liner
3 : cylinder cover
4 : Cylinder
4a: longitudinal axis
5 : Piston
6: exhaust valve
6a: valve body
6b: valve rod
7: exhaust valve seat
7a: exhaust port
8: combustion chamber
9: exhaust valve box
9a: exhaust port
10: valve rod guide
11: upper valve operating device
13a, 13b: bolt
15: gasket
15a: Give me
16: Gap
31: cylinder cover seat
31a: inner circumferential end
31b: outer periphery
31c: outer peripheral end
32: hanging part
32a: side wall
33: groove
71: valve seat seat portion
71b: outer periphery
71c: outer peripheral end

Claims (5)

Joining a cylinder cover of a cylinder having a combustion chamber of a marine diesel engine and an exhaust valve seat on which an exhaust valve for opening and closing an exhaust port of the combustion chamber is seated by interposing an annular gasket surrounding the longitudinal axis of the cylinder. As a seat portion structure for,
The cylinder cover,
a cylinder cover sheet portion formed in an annular shape so as to surround a longitudinal axis of the cylinder and having an outer diameter larger than that of the gasket, on which the gasket is placed;
a locking portion formed along an inner circumferential end of the cylinder cover seat portion and engaging the gasket by contacting with an inner circumferential surface of the gasket mounted on the cylinder cover seat portion;
The exhaust valve seat is annularly formed to face the cylinder cover seat portion with the gasket therebetween, and includes a valve seat seat portion having an outer diameter larger than an outer diameter of the gasket. According to claim 1,
The seat portion structure, characterized in that the locking portion is formed in a convex shape protruding toward the valve seat seat portion rather than the cylinder cover seat portion. According to claim 1,
The seat portion structure characterized in that the locking portion is formed in an annular or arcuate shape along an inner circumferential end of the cylinder cover seat portion. According to claim 2,
The seat portion structure, characterized in that the locking portion is formed in an annular or arcuate shape along an inner circumferential end of the cylinder cover seat portion. According to any one of claims 1 to 4,
The cylinder cover is a seat portion structure, characterized in that further provided with a groove portion along the outer peripheral end of the engaging portion.

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