JP7241512B2 - cooling structure - Google Patents

Description

The present invention relates to a cooling structure for an exhaust valve box of a marine diesel engine.

Conventionally, a cooling structure for a marine diesel engine mounted on a ship has been proposed. For example, in the cooling structure described in Patent Document 1, cooling water is supplied from the lower edge portion of the cylinder cover, and the supplied cooling water flows through the flow path in the cylinder cover to the upper portion of the cylinder cover. . This allows the cylinder cover and the structures above it to be cooled by the cooling water.

In a marine diesel engine, an exhaust valve box is provided above a cylinder cover. Generally, an exhaust port, which is an exhaust gas path for discharging exhaust gas from a combustion chamber of a cylinder, is formed in an exhaust valve box. Further, in the exhaust valve box, the valve stems of the exhaust valves that open and close between the combustion chamber and the exhaust port are slidably supported by valve stem guides that guide the sliding movement of the valve stems.

In order to maintain smooth sliding of the valve stem in the valve stem guide section, lubricating oil is supplied to the valve stem guide section to form an appropriate film of lubricating oil between the valve stem guide section and the valve stem. There is a need to. However, in the exhaust valve box, the heat of the high-temperature exhaust gas flowing through the exhaust port is transmitted to the valve rod guide portion, which may cause the temperature of the valve rod guide portion to rise excessively. In this case, since the viscosity of the lubricating oil supplied to the valve stem guide portion is lowered, the valve stem guide portion is in a state where it is difficult to maintain a film of lubricating oil between the valve stem and the valve stem, that is, the oil has run out. put away. This state hinders smooth sliding of the valve stem in the valve stem guide.

In order to avoid the oil-out condition described above, a cooling chamber is formed in the exhaust valve box in the vicinity of the valve stem guide. Further, a flow path is formed in the side wall of the exhaust valve box from the lower cylinder cover side to the upper cooling chamber side. The valve stem guide portion is cooled by cooling water that has flowed into the cooling chamber through this flow path. In this way, the above-described excessive temperature rise of the valve stem guide portion is suppressed.

JP-A-10-54240

However, in the exhaust valve box described above, since the cooling water flow path is formed in the side wall facing the exhaust port, the cooling water flows in the vicinity of the exhaust port. In such a structure of the exhaust valve box, the exhaust gas flowing from the combustion chamber to the exhaust port is cooled by the cooling water in the flow path, which may cause the temperature of the exhaust gas in the exhaust port to drop excessively. There is As a result, sulfuric acid is generated from the exhaust gas in the exhaust port, and this sulfuric acid corrodes the inside of the exhaust valve box.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a cooling structure capable of

In order to solve the above-described problems and achieve the object, a cooling structure according to the present invention provides an exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine, and an exhaust gas path between the combustion chamber and the exhaust gas path. A cooling structure for an exhaust valve box having therein a valve stem guide part for guiding the sliding of the valve stem of an exhaust valve that opens and closes, wherein the exhaust valve box surrounds the outer periphery of the valve stem guide part. a cooling chamber for cooling the valve stem guide portion with cooling water, and a cooling chamber formed above the exhaust gas path inside the exhaust valve box and passing through the outside from the bottom side of the exhaust valve box and above the exhaust gas path. and an external water supply pipe arranged to communicate with the cooling chamber and supplying the cooling water to the cooling chamber.

Further, in the cooling structure according to the present invention, in the above invention, the external water supply pipe has a stress absorption structure that absorbs stress generated in the external water supply pipe due to thermal expansion of the exhaust valve box. do.

Further, in the cooling structure according to the present invention, in the above invention, the stress absorption structure includes a joint portion that joins the end portion of the pipe body of the external water supply pipe to the outer wall portion of the exhaust valve box, and and a sliding member that allows the end portion of the pipe body to slide in the direction of thermal elongation.

Further, in the cooling structure according to the present invention, in the above invention, the stress absorbing structure is a joint that joins the end of the pipe main body of the external water supply pipe to the upper part of the cylinder cover located below the exhaust valve box. and a sliding member that enables the end of the pipe body to slide with respect to the joint in the direction of thermal elongation.

Further, the cooling structure according to the present invention is characterized in that, in the above invention, the stress absorption structure is constituted by a pipe body having a variable structure that enables expansion and contraction of the external water supply pipe in a thermal expansion direction.

Further, in the cooling structure according to the present invention, in the above invention, an internal flow path is formed above the exhaust gas path in the exhaust valve box and joins the cooling chamber along the circumferential direction of the cooling chamber. The external water supply pipe communicates with the cooling chamber through the internal channel.

Further, in the above invention, the cooling structure according to the present invention is formed above the exhaust gas path in the exhaust valve box, and the cooling chamber is provided on the side opposite to the cooling water outlet with the cooling chamber interposed therebetween. and the external water supply pipe communicates with the cooling chamber through the internal flow path.

Moreover, the cooling structure according to the present invention is characterized in that, in the above invention, a plurality of the external water supply pipes are arranged.

Advantageous Effects of Invention According to the present invention, it is possible to suppress the occurrence of sulfuric acid corrosion in the exhaust valve box and to cool the valve rod guide portion provided in the exhaust valve box.

FIG. 1 is a schematic diagram showing a configuration example of the vicinity of an exhaust valve box of a marine diesel engine according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view showing one configuration example of the cooling structure according to Embodiment 1 of the present invention. FIG. 3 is a schematic diagram of the cooling structure according to Embodiment 1 of the present invention as viewed from the upper side of the exhaust valve box. FIG. 4 is a schematic cross-sectional view showing an example of the stress absorbing structure of the external water supply pipe according to Embodiment 1 of the present invention. FIG. 5 is a schematic diagram showing a modified example of the stress absorption structure of the external water supply pipe according to Embodiment 1 of the present invention. FIG. 6 is a schematic cross-sectional view showing one configuration example of a cooling structure according to Embodiment 2 of the present invention. FIG. 7 is a schematic cross-sectional view showing one configuration example of a cooling structure according to Embodiment 3 of the present invention. FIG. 8 is a schematic cross-sectional view showing one configuration example of a cooling structure according to Embodiment 4 of the present invention.

Preferred embodiments of the cooling structure according to the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited by this embodiment. Also, it should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may differ from the actual ones. Even between the drawings, there are cases where portions with different dimensional relationships and ratios are included. Moreover, in each drawing, the same code|symbol is attached|subjected to the same component.

(Embodiment 1)
(Construction of Marine Diesel Engine)
First, the configuration of a marine diesel engine provided with an exhaust valve box having a cooling structure according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram showing a configuration example of the vicinity of an exhaust valve box of a marine diesel engine according to Embodiment 1 of the present invention. A marine diesel engine 1 shown in FIG. 1 is a propulsion engine (main engine) that rotates a marine propulsion propeller (none of which is shown) via a propeller shaft. For example, the marine diesel engine 1 is a two-stroke diesel engine such as a known uniflow sweep-exhaust crosshead diesel engine. As the marine diesel engine 1, a six-cylinder engine or the like can be used, but the number of cylinders is not particularly limited. Further, the operation control method of the marine diesel engine 1 includes a cam method, an electronic control method, and the like, but is not particularly limited.

The configuration of the vicinity of the exhaust valve box of the marine diesel engine 1 is the same for all cylinders. Therefore, the configuration around the exhaust valve box of the marine diesel engine 1 for one of the cylinders will be described below.

As shown in FIG. 1, a marine diesel engine 1 includes a cylinder liner 2, a cylinder cover 3, a piston 4, a piston rod 5, an exhaust valve 6, an exhaust valve seat 7, a fuel injection valve 9, an exhaust It includes a valve box 10 , a cover 12 , a connecting pipe 14 and an exhaust manifold 15 .

The cylinder liner 2 is a tubular structure, and a cylinder cover 3 is attached to the upper portion of the cylinder liner 2 . These cylinder liner 2 and cylinder cover 3 constitute one cylinder in the marine diesel engine 1, and form a cylindrical space in which the piston 4 reciprocates (that is, a space within the cylinder). The piston 4 is provided in this space so as to be reciprocally movable. An upper portion of a piston rod 5 is connected to the lower portion of the piston 4 . Although not shown, the lower portion of the piston rod 5 is connected to the crankshaft via a crosshead or the like. This crankshaft is connected to an output shaft such as a crankshaft that rotates in conjunction with the reciprocating movement of the piston 4 .

The exhaust valve 6 includes a valve body 6a and a valve stem 6b. The exhaust valve seat 7 is incorporated in the upper part of the cylinder cover 3, is configured so that the valve body 6a of the exhaust valve 6 can be seated thereon, and forms an exhaust port 7a. A combustion chamber 8 in the cylinder is formed by the cylinder liner 2, the cylinder cover 3, the piston 4, and the valve body 6a. The fuel injection valve 9 is attached to the cylinder cover 3 and configured to inject fuel (heavy oil, light oil, etc.) into the combustion chamber 8 .

The exhaust valve box 10 is attached to the upper part of the cylinder (the upper part of the cylinder cover 3 constituting the cylinder in the first embodiment). As a result, the lower end of the exhaust valve box 10 is connected to the upper end of the exhaust valve seat 7 assembled in the upper portion of the cylinder cover 3 . An exhaust port 10 a communicating with the exhaust port 7 a of the exhaust valve seat 7 is formed inside the exhaust valve box 10 . A valve rod guide portion 11 is incorporated inside the exhaust valve box 10 . The exhaust valve box 10 slidably supports the valve stem 6 b of the exhaust valve 6 via the valve stem guide portion 11 .

The cover 12 is attached to the upper portion of the exhaust valve box 10 and accommodates an exhaust valve operating device 13 configured to allow the exhaust valve 6 to reciprocate. The exhaust valve actuation device 13 is provided with an urging member (not shown) such as a compression spring or an air spring. It is supported in the upright position. The exhaust valve actuation device 13 is also connected to a fuel pump (not shown) through a pipe. When the hydraulic oil is supplied from the oil supply pump through the pipe, the exhaust valve operating device 13 lowers the exhaust valve 6 against the biasing member by the hydraulic pressure of the hydraulic oil. In this manner, the exhaust valve actuation device 13 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 exhaust valve operating device 13, and closes the exhaust port 7a when the supply of this hydraulic oil is stopped.

The connection pipe 14 connects the exhaust port 10 a formed in the exhaust valve box 10 and the exhaust manifold 15 . The exhaust manifold 15 receives exhaust gas from the combustion chamber 8 of the marine diesel engine 1 through the exhaust ports 7a and 10a and the connecting pipe 14, temporarily stores the received exhaust gas, and converts the dynamic pressure of the exhaust gas to static pressure.

In the marine diesel engine 1, after a combustion gas such as air is introduced into the combustion chamber 8 from a scavenging port (not shown), the piston 4 rises and the exhaust port 7a is closed by the exhaust valve 6, whereby the combustion chamber 8 The combustion gas inside is compressed. When the piston 4 reaches the top dead center, the pressure inside the combustion chamber 8 reaches a predetermined compression pressure, and the fuel injection valve 9 injects fuel. Then, the combustion gas and the fuel are mixed and burned in the combustion chamber 8, and the combustion energy causes the piston 4 to descend. By opening the exhaust port 7a by the exhaust valve 6 at a predetermined timing, the exhaust gas in the combustion chamber 8 is discharged to the exhaust port 10a in the exhaust valve box 10 through the exhaust port 7a of the exhaust valve seat 7. After that, the exhaust gas is discharged from the exhaust port 10 a to the exhaust manifold 15 through the connecting pipe 14 .

(cooling structure)
Next, a cooling structure according to Embodiment 1 of the present invention will be described. The cooling structure according to Embodiment 1 is, for example, a cooling structure for the exhaust valve box 10 of the marine diesel engine 1 . FIG. 2 is a schematic cross-sectional view showing one configuration example of the cooling structure according to Embodiment 1 of the present invention. FIG. 3 is a schematic diagram of the cooling structure according to Embodiment 1 of the present invention as viewed from the upper side of the exhaust valve box.

As described above, the exhaust valve box 10 has the exhaust port 10a and the valve stem guide portion 11 therein. The exhaust port 10 a is an exhaust gas path for discharging exhaust gas from the combustion chamber 8 of the marine diesel engine 1 and communicates with the exhaust port 7 a of the exhaust valve seat 7 leading to the combustion chamber 8 . The valve stem guide portion 11 guides the sliding of the valve stem 6b of the exhaust valve 6 that opens and closes between the combustion chamber 8 and the exhaust port 10a (that is, the exhaust port 7a). The valve stem guide part 11 is, for example, a cylindrical structure, and extends from the lower part of the cover 12 (upper end of the exhaust valve box 10) to the upper part of the exhaust port 10a. provided inside. A valve stem 6 b of the exhaust valve 6 is slidably inserted through the valve stem guide portion 11 . The exhaust valve box 10 supports the valve stem 6b through the valve stem guide portion 11 while restricting the sliding direction of the valve stem 6b to a predetermined direction (for example, the vertical direction of the exhaust valve box 10). 2 and 3, the cooling structure of the exhaust valve box 10 includes a cooling chamber 21, external water supply pipes 22 and 23, lower passages 24a and 24b, and internal passages 25a, 25b and 25c. and

The cooling chamber 21 is a space for cooling the valve rod guide portion 11 with cooling water. As shown in FIGS. 2 and 3, the cooling chamber 21 is formed above the exhaust port 10a inside the exhaust valve box 10 so as to surround the outer periphery of the valve rod guide portion 11 (for example, formed in an annular shape).

The external water supply pipes 22 and 23 are an example of a plurality of external water supply pipes for supplying cooling water to the cooling chamber 21 . As shown in FIGS. 2 and 3, the external water supply pipes 22 and 23 are arranged to communicate with the cooling chamber 21 above the exhaust port 10a through the outside of the exhaust valve box 10 from below. In addition, in Embodiment 1, the external water supply pipes 22 and 23 each have a stress absorbing structure that absorbs the stress generated in the external water supply pipes 22 and 23 due to thermal elongation (thermal expansion) of the exhaust valve box 10. .

In Embodiment 1, for example, as shown in FIG. and joint portions 22b and 22c that are joined to the portions.

The pipe main body 22a avoids contact with the outer wall of the exhaust valve box 10 and a structure protruding from the outer wall (for example, the flange of the exhaust port 10a), and extends from the bottom to the top of the exhaust valve box 10. It is piped outside the exhaust valve box 10 so as to extend. One end (inflow end) of the pipe body 22a is joined to the lower portion of the outer wall of the exhaust valve box 10 by a joint 22b. As this lower part, for example, an outer wall part in the vicinity of the inlet end of the exhaust port 10a of the exhaust valve box 10 (preferably the lower side) can be cited. The other end (outflow end) of the pipe main body 22a is joined to the upper portion of the outer wall of the exhaust valve box 10 by a joint 22c. Examples of the upper portion include an outer wall portion above the exhaust port 10a of the exhaust valve box 10, and the like.

The joint portion 22b has a flow path 22ba inside. The joint portion 22b joins the inflow end of the pipe main body 22a to the lower portion of the outer wall portion of the exhaust valve box 10 by fastening or the like, and connects the lower flow path 24a of the exhaust valve box 10 and the pipe main body through the flow passage 22ba. 22a. On the other hand, the joint portion 22c is connected to the upper portion of the outer wall portion of the exhaust valve box 10 by fastening or the like so that the internal flow path 25a of the upper portion of the exhaust valve box 10 and the pipe main body 22a communicate with each other. join the parts.

Further, in the first embodiment, as shown in FIG. 2, for example, the external water supply pipe 23 is arranged on the opposite side of the above-described external water supply pipe 22 with the exhaust valve box 10 interposed therebetween. The external water supply pipe 23 includes a pipe main body 23a for circulating cooling water outside the exhaust valve box 10, and joints 23b and 23c for joining the ends of the pipe main body 23a to the outer wall of the exhaust valve box 10.

The pipe main body 23a avoids contact with the outer wall portion of the exhaust valve box 10 and a structure protruding from the outer wall portion on the opposite side of the above-described pipe main body 22a across the exhaust valve box 10. It is piped outside the exhaust valve box 10 so as to extend from the bottom to the top of the exhaust valve box 10 . One end (inflow end) of the pipe main body 23a is joined to the lower portion of the outer wall portion of the exhaust valve box 10 by a joint portion 23b. The other end (outflow end) of the pipe main body 23a is joined to the upper portion of the outer wall of the exhaust valve box 10 by a joint 23c.

The joint portion 23b has a flow path 23ba inside. On the opposite side of the exhaust valve box 10 from the joint part 22b described above, the joint part 23b joins the inflow end of the pipe main body 23a to the lower portion of the outer wall of the exhaust valve box 10 by fastening or the like. The lower flow path 24b of the exhaust valve box 10 and the pipe main body 23a are communicated through the flow path 23ba. Also, the joint portion 23c has a flow path 23ca inside. On the opposite side of the exhaust valve box 10 from the above-described joint part 22c, the joint part 23c joins the outflow end of the pipe body 23a to the upper part of the outer wall of the exhaust valve box 10 by fastening or the like, and The internal flow path 25c in the upper portion of the exhaust valve box 10 and the pipe main body 23a are communicated via the path 23ca.

Further, as shown in FIG. 2, lower flow paths 24a and 24b are formed on the lower side of the outer wall portion of the exhaust valve box 10. As shown in FIG. Each of the lower flow paths 24 a and 24 b has one end opening to the lower end surface of the outer wall portion of the exhaust valve box 10 and the other end opening to the side wall surface of the outer wall portion of the exhaust valve box 10 . It is formed in the lower portion within the outer wall of 10 . Here, inside the exhaust valve seat 7, as shown in FIG. A cooling water passage 7b extending to (seat portion) is formed. Cooling water is supplied to the cooling water passage 7b through a channel (not shown) formed inside the cylinder cover 3, for example. The cooling water supplied to the cooling water passage 7b cools the exhaust valve seat 7 (especially the seat portion).

Circumferential grooves 7c are formed between the cooling water passages 7b of the exhaust valve seat 7 and the lower passages 24a and 24b of the exhaust valve box 10, as shown in FIG. For example, the circumferential groove 7c is formed in a circular or rectangular annular shape along the boundary between the exhaust valve seat 7 and the exhaust valve box 10 so as to surround the exhaust port 7a. The circumferential groove 7 c is formed in at least one of the exhaust valve seat 7 and the exhaust valve box 10 . In the first embodiment, they are provided at each end of the exhaust valve seat 7 and the exhaust valve box 10 across the boundary between the exhaust valve seat 7 and the exhaust valve box 10 . As shown in FIG. 2, the cooling water passage 7b communicates with the above-described lower flow passages 24a and 24b through a circumferential groove 7c. That is, one lower flow passage 24a communicates the cooling water passage 7b and the flow passage 22ba in the joint portion 22b through the circumferential groove 7c, and the other lower flow passage 24b communicates the cooling water passage 7b and the joint portion 23b through the circumferential groove 7c. It communicates with the internal flow path 23ba.

Further, as shown in FIG. 2, internal flow paths 25a, 25b, and 25c are formed above the exhaust port 10a inside the exhaust valve box 10. As shown in FIG. Of these internal flow paths 25a, 25b, 25c, the internal flow paths 25a, 25b are for communicating one of the external water supply pipes 22 and the cooling chamber 21, and the internal flow path 25c is for communicating with the other external water supply pipe. 23 and the cooling chamber 21 are communicated with each other.

Specifically, as shown in FIGS. 2 and 3, one end of the internal flow path 25a is open to the side wall surface of the outer wall of the exhaust valve box 10, and the other end is connected to the middle portion of the internal flow path 25b. , is formed above the exhaust port 10a. Such an internal flow path 25a allows the external water supply pipe 22 joined to the outer wall of the exhaust valve box 10 as described above and the internal flow path 25b to communicate above the exhaust port 10a. On the other hand, the internal flow path 25b is formed above the exhaust port 10a so that one end is connected to the cooling chamber 21 and the other end opens to the upper end surface of the exhaust valve box 10 . The opening of this internal flow path 25b constitutes a cooling water outlet 26, as shown in FIGS. Further, the internal flow path 25b is connected to the internal flow path 25a at the midpoint as described above. Such an internal flow path 25b communicates the internal flow path 25a leading to the external water supply pipe 22 and the cooling chamber 21 above the exhaust port 10a as described above.

In the first embodiment, the internal flow path 25b merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21, as shown in FIG. 3, for example. The external water supply pipe 22 communicates with the cooling chamber 21 through internal flow paths 25a and 25b. That is, these internal flow paths 25a and 25b connect the cooling chamber 21 and the external water supply pipe 22 above the exhaust port 10a, and the internal flow merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21. compose the road.

On the other hand, as shown in Figs. It is formed above 10a. Such an internal flow path 25c communicates the external water supply pipe 23 joined to the outer wall portion of the exhaust valve box 10 and the cooling chamber 21 above the exhaust port 10a as described above. 2 and 3, the internal flow path 25c merges with the cooling chamber 21 on the opposite side of the cooling water outlet 26 with the cooling chamber 21 interposed therebetween. The external water supply pipe 23 communicates with the cooling chamber 21 through the internal flow path 25c on the opposite side of the external water supply pipe 22 with the exhaust valve box 10 interposed therebetween. It should be noted that "the side opposite to the cooling water outlet 26 across the cooling chamber 21" is, for example, when the exhaust valve box 10 is viewed from above as shown in FIG. means the positional relationship between the internal flow path 25 c and the cooling water outlet 26 such that the line segment connecting the center point of the confluence of the two and the center point of the cooling water outlet 26 intersects the cooling chamber 21 .

In the cooling structure configured as described above, the cooling water flows into the cooling water passage 7b inside the exhaust valve seat 7 from a passage (not shown) inside the cylinder cover 3, for example. The cooling water in the cooling water passage 7b flows through the circumferential groove 7c into the lower passage 24a in the outer wall portion of the exhaust valve box 10, and from the lower passage 24a through the external water supply pipe 22, the exhaust in the exhaust valve box 10. It is guided above the port 10a. Specifically, the cooling water flows from the lower channel 24a into the pipe body 22a through the flow channel 22ba in the joint 22b of the external water supply pipe 22, and flows into the internal channel 25a of the exhaust valve box 10 through the pipe body 22a. . After that, the cooling water flows into the cooling chamber 21 from the internal flow path 25a above the exhaust port 10a in the exhaust valve box 10 through the internal flow path 25b.

In parallel with this, the cooling water in the cooling water passage 7b flows through the circumferential groove 7c into the lower passage 24b in the outer wall portion of the exhaust valve box 10, and is exhausted through the external water supply pipe 23 from the lower passage 24b. It is guided above the exhaust port 10 a in the valve box 10 . Specifically, the cooling water flows from the lower flow path 24b into the pipe main body 23a through the flow passage 23ba in the joint portion 23b of the external water supply pipe 23, and passes through the pipe main body 23a and the flow passage 23ca in the joint portion 23c in this order. and flows into the internal flow path 25 c of the exhaust valve box 10 . After that, the cooling water flows into the cooling chamber 21 through the internal flow path 25c above the exhaust port 10a in the exhaust valve box 10. As shown in FIG.

As described above, the cooling water flowing into the cooling chamber 21 cools the valve rod guide portion 11 through the wall of the cooling chamber 21 while flowing in the cooling chamber 21 . For example, the internal flow path 25b is a flow path that merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21 as shown in FIG. The cooling water supplied to 21 flows in the cooling chamber 21 in the circumferential direction. As a result, the cooling water is prevented from remaining in the cooling chamber 21 and is discharged from the cooling water outlet 26 while circulating in the cooling chamber 21 to replace the newly supplied cooling water. In addition, since the internal flow path 25c is a flow path that merges with the cooling chamber 21 on the opposite side of the cooling water outlet 26 across the cooling chamber 21 as shown in FIG. The cooling water circulation path in the cooling chamber 21 from the junction with the cooling water outlet 26 to the cooling water outlet 26 is longer than in the case of being on the same side as the cooling water outlet 26 . As a result, the cooling water supplied from the external water supply pipe 23 to the cooling chamber 21 through the internal flow path 25c flows in the cooling chamber 21 for a relatively long distance before being discharged from the cooling water outlet 26. become.

When the cooling water flowing in the cooling chamber 21 cools the valve rod guide portion 11 as described above, the cooling water in the cooling chamber 21 is transmitted from the exhaust gas in the exhaust port 10a to the valve rod guide portion 11. By removing the heat, the temperature rise of the valve stem guide portion 11 is suppressed. Lubricating oil is supplied between the valve stem guide portion 11 and the valve stem 6b of the exhaust valve 6 to facilitate the sliding of the valve stem 6b in the valve stem guide portion 11. As shown in FIG. This lubricating oil forms an oil film between the valve stem guide portion 11 and the valve stem 6b. Since the valve stem guide portion 11 is cooled by the cooling water in the cooling chamber 21 as described above, this lubricating oil has an appropriate viscosity and retains the oil film. As a result, smooth sliding of the valve stem 6b in the valve stem guide portion 11 is maintained. The cooling water used for cooling the valve stem guide portion 11 flows from the cooling chamber 21 through the internal flow path 25b to the cooling water outlet 26, and from the cooling water outlet 26 to the outside of the exhaust valve box 10 through piping or the like (not shown). discharged to

(Stress absorption structure of external water supply pipe)
Next, the stress absorption structure of the external water supply pipe in the cooling structure according to Embodiment 1 of the present invention will be described. The exhaust valve box 10 may thermally expand due to the heat of high-temperature exhaust gas discharged from the combustion chamber 8 to the exhaust port 10a. As shown in FIGS. 2 and 3, the external water supply pipes 22 and 23 connected to the outer wall of the exhaust valve box 10 are subjected to stress (e.g., tensile stress) due to tension due to thermal expansion of the exhaust valve box 10. ) may occur. In order to prevent damage to the external water supply pipes 22, 23 due to the stress, the external water supply pipes 22, 23 are provided with a stress absorbing structure that absorbs the stress.

FIG. 4 is a schematic cross-sectional view showing an example of the stress absorbing structure of the external water supply pipe according to Embodiment 1 of the present invention. FIG. 4 illustrates the stress absorption structure of the external water supply pipe 23 as an example of the stress absorption structure.

As shown in FIG. 4, in the external water supply pipe 23, the joint portion 23b internally includes the above-described flow path 23ba and an engaging portion 23bb that communicates with the flow path 23ba. The inflow end portion 23aa of the pipe main body 23a is fitted into the engaging portion 23bb of the joint portion 23b. As a result, the inflow end portion 23aa is engaged with the engaging portion 23bb, and the pipe main body 23a communicates with the flow path 22ba in the joint portion 23b. An O-ring 27a is interposed between the inflow end portion 23aa and the engaging portion 23bb. The O-ring 27a is an example of a sliding member that allows the end of the pipe body 23a (inflow end 23aa in FIG. 4) to slide in the thermal expansion direction F1 with respect to the joint 23b. The pipe main body 23a is connected to the joint portion 23b by an O-ring 27a such that the inflow end portion 23aa is slidable relative to the engaging portion 23bb in the thermal expansion direction F1. That is, the inflow end portion 23aa of the pipe main body 23a is a free end that is slidably engaged with the engaging portion 23bb of the joint portion 23b in the thermal extension direction F1.

Further, in the external water supply pipe 23, the joint portion 23c includes therein the above-described flow path 23ca and an engagement portion 23cb communicating with the flow path 23ca. The outflow end portion 23ab of the pipe main body 23a is fitted into the engagement portion 23cb of the joint portion 23c. As a result, the outflow end portion 23ab is engaged with the engaging portion 23cb, and the pipe main body 23a communicates with the flow path 23ca in the joint portion 23c. An O-ring 27b is interposed between the outflow end portion 23ab and the engaging portion 23cb. The O-ring 27b is an example of a sliding member that allows the end of the pipe body 23a (the outflow end 23ab in FIG. 4) to slide in the thermal expansion direction F1 with respect to the joint 23c. The pipe main body 23a is connected to the joint portion 23c by an O-ring 27b such that the outflow end portion 23ab is slidable in the thermal expansion direction F1 with respect to the engaging portion 23cb. In other words, the outflow end portion 23ab of the pipe main body 23a is a free end that is slidably engaged with the engaging portion 23cb of the joint portion 23c in the thermal expansion direction F1.

The O-rings 27a, 27b are provided on the inner wall portions of the engaging portions 23bb, 23cb of the joint portions 23b, 23c, respectively, but are not limited to this, and the inflow end portion 23aa and the outflow end portion of the pipe main body 23a. 23ab may be provided on the outer wall.

In the first embodiment, the stress absorption structure of the external water supply pipe 23 includes joint portions 23b and 23c that join the inflow end portion 23aa and the outflow end portion 23ab of the pipe main body 23a to the outer wall portion of the exhaust valve box 10, and the joint portion 23b , 23c, and O-rings 27a and 27b that allow the inflow end 23aa and outflow end 23ab of the pipe body 23a to slide in the thermal expansion direction F1. In this stress absorbing structure, for example, as shown in FIG. It changes to state A2 after thermal elongation.

Specifically, as shown in FIG. 4, the joint portion 23b is displaced downward in the thermal expansion direction F1 together with the thermally expanded outer wall portion of the exhaust valve box 10. As shown in FIG. At this time, the inflow end portion 23aa of the pipe main body 23a slides relative to the engaging portion 23bb via the O-ring 27a while maintaining the state of being engaged with the engaging portion 23bb of the joint portion 23b. do. This suppresses the generation of stress between the joint portion 23b and the inflow end portion 23aa of the pipe main body 23a. In parallel with this, the joint portion 23c is displaced upward in the thermal expansion direction F1 together with the thermally expanded outer wall portion of the exhaust valve box 10 . At this time, the outflow end portion 23ab of the pipe main body 23a slides relative to the engaging portion 23cb via the O-ring 27b while maintaining the state of being engaged with the engaging portion 23cb of the joint portion 23c. do. This suppresses the generation of stress between the joint portion 23c and the outflow end portion 23ab of the pipe main body 23a. The sliding action between the pipe body 23a and the joints 23b and 23c by the O-rings 27a and 27b absorbs the stress of the external water supply pipe 23 due to thermal expansion of the exhaust valve box 10. FIG.

After that, as the exhaust valve box 10 thermally contracts, the joints 23b and 23c change from the state A2 after thermal expansion to the state A1 before thermal expansion. In this case, the joints 23b and 23c are displaced in the direction opposite to that in the case of thermal elongation described above. With this displacement, the inflow end 23aa and the outflow end 23ab of the pipe body 23a slide relative to the engaging portions 23bb and 23cb of the joint portions 23b and 23c via O-rings 27a and 27b, respectively. do.

Although not shown in particular, in the first embodiment, the stress absorbing structure of the external water supply pipe 22 has the inflow end of the pipe main body 22a as a free end that is slidably engaged with the joint 22b in the thermal expansion direction F1. , the outflow end of the pipe main body 22a is used as a fixed end fixed to the outer wall of the exhaust valve box 10 by a joint 22c. In this stress absorption structure, the joint portion 22b has the same configuration as the joint portion 23b of the stress absorption structure of the external water supply pipe 23 described above. An O-ring (not shown) is provided between the joint 22b and the inflow end of the pipe body 22a to allow the inflow end of the pipe body 22a to slide with respect to the joint 22b in the thermal expansion direction F1. is provided.

In such a stress absorbing structure, stress generation between the joint 22b and the inflow end of the pipe body 22a and stress generation between the joint 22c and the outflow end of the pipe body 22a can be This is suppressed by the sliding action of the O-ring between the pipe body 22a and the joint portion 22b. As a result, the stress of the external water supply pipe 22 due to thermal expansion of the exhaust valve box 10 is absorbed. After that, as with the external water supply pipe 23 described above, the external water supply pipe 22 changes from the state after thermal expansion to the state before thermal expansion as the exhaust valve box 10 thermally contracts.

(Modified example of stress absorption structure)
Next, a modified example of the stress absorption structure of the external water supply pipe in the present invention will be described. FIG. 5 is a schematic diagram showing a modified example of the stress absorption structure of the external water supply pipe according to Embodiment 1 of the present invention. FIG. 5 illustrates the stress absorption structure of the external water supply pipe 33 as a modified example of the stress absorption structure. In this modification, the external water supply pipe 33 is joined to the outer wall portion of the exhaust valve box 10 in place of the external water supply pipe 23 shown in FIG. In addition, in the external water supply pipe 33 shown in FIG. 5, the same components as those of the external water supply pipe 23 described above are denoted by the same reference numerals.

As shown in FIG. 5, in the external water supply pipe 33, the pipe main body 33a is a pipe with a variable structure that allows expansion and contraction of the external water supply pipe 33 in the thermal expansion direction F1. As the variable structure of the pipe body 33a, for example, a U-shaped pipe structure, an S-shaped pipe structure, or the like shown in FIG. tubular structures. The joint portion 23b has therein the above-described flow path 23ba. An inflow end portion 33aa of the pipe main body 33a is fixed to the joint portion 23b by fastening or the like so that the pipe main body 33a and the flow path 23ba communicate with each other. Moreover, the junction part 23c has the flow path 23ca mentioned above inside. An outflow end portion 33ab of the pipe main body 33a is fixed to the joint portion 23c by fastening or the like so that the pipe main body 33a and the flow path 23ca communicate with each other. That is, in this modification, an inflow end 33aa and an outflow end 33ab of the pipe body 33a are fixed ends fixed to the joints 23b and 23c, respectively.

The stress absorption structure of the external water supply pipe 33 according to this modification is constituted by a pipe body 33a having a variable structure that allows the external water supply pipe 33 to expand and contract in the thermal expansion direction F1. In this stress absorbing structure, for example, as shown in FIG. It is displaced in the direction F1).

Specifically, as shown in FIG. 5, the joint portion 23b is displaced downward in the thermal expansion direction F1 together with the thermally expanded outer wall portion of the exhaust valve box 10. As shown in FIG. In parallel with this, the joint portion 23c is displaced upward in the thermal expansion direction F1 together with the thermally expanded outer wall portion of the exhaust valve box 10 . At this time, the pipe body 33a is deformed so as to open the variable structure pipe portion (the U-shaped pipe portion in FIG. 5) according to the amount of displacement of the joints 23b and 23c (the amount of increase in the separation distance). , in the thermal elongation direction F1. As a result, the occurrence of stress between the joints 23b, 23c and the respective ends of the pipe body 33a is suppressed, so that the stress of the external water supply pipe 33 due to the thermal expansion of the exhaust valve box 10 is absorbed.

After that, as the exhaust valve box 10 thermally contracts, the joints 23b and 23c change from the state after the thermal expansion to the state before the thermal expansion. In this case, the joints 23b and 23c are displaced in the direction opposite to that in the case of thermal elongation described above. Along with this displacement, the pipe main body 33a is deformed so as to close the pipe portion of the variable structure according to the amount of displacement of the joints 23b and 23c (the amount of decrease in the separation distance), and shrinks in the thermal elongation direction F1.

Although not shown, the stress absorbing structure according to this modification can also be applied to the external water supply pipe 22 . For example, the stress absorption structure of the external water supply pipe 22 is composed of a pipe body 22a having a variable structure that allows the external water supply pipe 22 to expand and contract in the thermal expansion direction F1. The inflow and outflow ends of the tube body 22a are secured to joints 22b, 22c, respectively. The stress absorption structure of this external water supply pipe 22 operates in the same manner as the stress absorption structure of the external water supply pipe 33 shown in FIG.

As described above, in the cooling structure according to the first embodiment of the present invention, the inside of the exhaust valve box 10 is provided so as to surround the outer periphery of the valve stem guide portion 11 that guides the sliding of the valve stem 6b of the exhaust valve 6. A cooling chamber 21 is formed above the exhaust port 10a, and external water supply pipes 22 and 23 for supplying cooling water used for cooling the valve stem guide portion 11 to the cooling chamber 21 are provided below the exhaust valve box 10. It is piped so as to communicate with the cooling chamber 21 above the exhaust port 10a through the outside from the side.

Therefore, cooling water can be supplied to the cooling chamber 21 inside the exhaust valve box 10 by bypassing the side wall facing the exhaust port 10a of the exhaust valve box 10 . As a result, it is possible to avoid a situation in which the temperature of the exhaust gas in the exhaust port 10a is excessively lowered by the cooling water. As a result, the generation of sulfuric acid from the exhaust gas in the exhaust port 10a can be suppressed, so that the occurrence of sulfuric acid corrosion in the exhaust valve box 10 can be suppressed, and the valve stem guide portion 11 provided in the exhaust valve box 10 can be prevented. It can be cooled by cooling water in the cooling chamber 21 . Further, by cooling the valve stem guide portion 11, it is possible to suppress an excessive decrease in the viscosity of the lubricating oil between the valve stem guide portion 11 and the valve stem 6b. As a result, an appropriate film of lubricating oil can be formed between the valve stem guide portion 11 and the valve stem 6b, so that smooth sliding of the valve stem 6b in the valve stem guide portion 11 can be maintained.

Here, as an example of the marine diesel engine 1, there is a cam-type engine in which the engine operation such as fuel injection into the combustion chamber is controlled by the rotation of a cam. engine is being developed. Generally, cam engines are tuned to optimize engine operation for a given engine load. On the other hand, an electronically controlled engine can be tuned not only when the engine load is 0% or 100%, but also when the engine load is in the range of more than 0% and less than 100% (so-called partial load). operation can be optimized. Therefore, an electronically controlled engine can improve fuel efficiency over a wider range of engine loads than a cam engine. On the other hand, the temperature of the exhaust gas decreases as the fuel efficiency improves. In other words, the problem of "sulfuric acid corrosion in the exhaust valve box due to sulfuric acid generated due to excessive temperature drop of exhaust gas in the exhaust port" tends to occur more prominently in electronically controlled engines than in cam-type engines. It is in. According to the cooling structure according to the first embodiment of the present invention, it is possible to avoid a situation in which the temperature of the exhaust gas in the exhaust port is excessively lowered by the cooling water. , can solve the above problem.

Further, in the cooling structure according to the first embodiment of the present invention, since the external water supply pipes 22 and 23 are arranged so as to pass through the outside of the exhaust valve box 10, the temperature of the exhaust gas rises due to the heat of the exhaust gas in the exhaust port 10a. Cooling water can be supplied to the cooling chamber 21 in the exhaust valve box 10 without passing through the side wall of the valve box 10 (the side wall facing the exhaust port 10a). As a result, it is possible to prevent the cooling water from being unintentionally heated by the heat of the exhaust gas while it is being supplied to the cooling chamber 21 . can be efficiently supplied to the cooling chamber 21, the cooling effect of the valve stem guide portion 11 by the cooling water can be enhanced.

In addition, in the cooling structure according to the first embodiment of the present invention, the external water supply pipes 22 and 23 are each provided with a stress absorption structure that absorbs stress generated in the pipes due to thermal expansion of the exhaust valve box 10 . Therefore, even if the exhaust valve box 10 thermally expands due to the heat of the exhaust gas in the exhaust port 10a, the stress generated in the external water supply pipes 22 and 23 due to this thermal expansion can be absorbed. As a result, it is possible to prevent the external water supply pipes 22 and 23 from being damaged by the stress associated with this thermal expansion.

In addition, in the cooling structure according to the first embodiment of the present invention, the internal flow path connecting the cooling chamber 21 and the external water supply pipe 22 merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21. It is formed above the exhaust port 10 a in the valve box 10 . Therefore, the cooling water supplied from the external water supply pipe 22 to the cooling chamber 21 through the internal channel can flow in the circumferential direction of the cooling chamber 21 . As a result, it is possible to prevent the cooling water from staying in the cooling chamber 21 and circulate the cooling water throughout the cooling chamber 21 . As a result, the improvement of the cooling effect of the valve stem guide portion 11 by the cooling water in the cooling chamber 21 can be promoted.

In addition, in the cooling structure according to the first embodiment of the present invention, the internal flow path that communicates the cooling chamber 21 and the external water supply pipe 23 is located on the side opposite to the cooling water outlet 26 with the cooling chamber 21 interposed therebetween. It is formed above the exhaust port 10a in the exhaust valve box 10 so as to merge. Therefore, the cooling water circulation path in the cooling chamber 21 from the confluence of the internal flow path and the cooling chamber 21 to the cooling water outlet 26 is a flow path formed on the same side as the cooling water outlet 26. can be made longer. As a result, the cooling water supplied from the external water supply pipe 23 to the cooling chamber 21 through the internal flow path is allowed to flow in the cooling chamber 21 for a relatively long distance before being discharged from the cooling water outlet 26. can be done. As a result, the improvement of the cooling effect of the valve stem guide portion 11 by the cooling water in the cooling chamber 21 can be promoted.

(Embodiment 2)
Next, a cooling structure according to Embodiment 2 of the present invention will be described. FIG. 6 is a schematic cross-sectional view showing one configuration example of a cooling structure according to Embodiment 2 of the present invention. A marine diesel engine according to Embodiment 2 includes an exhaust valve box 10A shown in FIG. 6 instead of the exhaust valve box 10 in Embodiment 1 described above. The exhaust valve box 10A includes external water supply pipes 42 and 43 instead of the external water supply pipes 22 and 23 in the first embodiment described above. Further, as shown in FIG. 6, the above-mentioned lower flow paths 24a and 24b are not formed in the outer wall portion of the exhaust valve box 10A, and cooling water paths 3a and 3b are formed in the cylinder cover 3 on the upper side. . A circumferential groove 7c is formed between the cooling water passages 3a, 3b and the cooling water passage 7b of the exhaust valve seat 7. As shown in FIG. The cooling structure according to the second embodiment is a cooling structure for such an exhaust valve box 10A. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

In the second embodiment, the cooling structure of the exhaust valve box 10A includes, for example, as shown in FIG. Flow channels 25a, 25b and 25c are provided.

As shown in FIG. 6, the external water supply pipe 42 includes a joint portion 42b instead of the joint portion 22b in the first embodiment described above. The inflow end of the pipe body 22a of the external water supply pipe 42 is joined to the upper portion of the cylinder cover 3 by a joint 42b so as to communicate with the cooling water passage 3a inside the cylinder cover 3. As shown in FIG. The configuration of the external water supply pipe 42 is the same as that of the external water supply pipe 22 in Embodiment 1, except that it is joined to the upper portion of the cylinder cover 3 by the joint portion 42b as described above.

The joint portion 42b has a flow path 42ba inside, as shown in FIG. The joint portion 42b joins the inflow end of the pipe body 22a to the upper portion of the cylinder cover 3 by fastening or the like, and communicates the cooling water passage 3a in the cylinder cover 3 with the pipe body 22a via the flow passage 42ba.

Further, as shown in FIG. 6, the external water supply pipe 43 includes a joint portion 43b instead of the joint portion 23b in the first embodiment described above. The inflow end of the pipe body 23a of the external water supply pipe 43 is joined to the upper portion of the cylinder cover 3 by a joint 43b so as to communicate with the cooling water passage 3b inside the cylinder cover 3. As shown in FIG. The configuration of the external water supply pipe 43 is the same as that of the external water supply pipe 23 in Embodiment 1, except that it is joined to the upper portion of the cylinder cover 3 by the joint portion 43b as described above.

The joint portion 43b has a flow path 43ba therein, as shown in FIG. The joining portion 43b joins the inflow end of the pipe main body 23a to the upper portion of the cylinder cover 3 by fastening or the like, and communicates the cooling water passage 3b in the cylinder cover 3 with the pipe main body 23a via the flow passage 43ba.

As described above, the cylinder cover 3 whose inflow ends are joined to the external water supply pipes 42, 43 by the joints 42b, 43b is a component that constitutes one cylinder in the marine diesel engine, As shown in FIG. 6, it is a portion positioned below the exhaust valve box 10A. In the second embodiment, as shown in FIG. 6, the cylinder cover 3 has cooling water passages 3a and 3b therein. Circumferential grooves 7c are formed between the cooling water passages 3a and 3b of the cylinder cover 3 and the cooling water passage 7b of the exhaust valve seat 7, as shown in FIG. The circumferential groove 7c is an annular groove, as in the first embodiment described above, and is formed in at least one of the cylinder cover 3 and the exhaust valve seat 7. As shown in FIG. In the second embodiment, they are provided at each end of the cylinder cover 3 and the exhaust valve seat 7 across the boundary between the cylinder cover 3 and the exhaust valve seat 7 . Each of the cooling water passages 3a and 3b has one end open to the upper end surface of the cylinder cover 3 and the other end communicates with the cooling water passage 7b in the exhaust valve seat 7 via the circumferential groove 7c. formed in the upper part of the Of these cooling water passages 3a and 3b, one cooling water passage 3a communicates the cooling water passage 7b in the exhaust valve seat 7 and the flow passage 42ba in the joint portion 42b through the circumferential groove 7c, and the other cooling water passage 3b communicates with , the cooling water passage 7b in the exhaust valve seat 7 and the flow passage 43ba in the joint portion 43b are communicated through the circumferential groove 7c.

In the cooling structure according to the second embodiment, the cooling water flows into the cooling water passage 7b inside the exhaust valve seat 7 from the lower flow path (not shown) inside the cylinder cover 3, for example. The cooling water in the cooling water passage 7b flows into the cooling water passage 3a in the cylinder cover 3 via the circumferential groove 7c, and flows from the cooling water passage 3a through the circulation passage 42ba in the joint portion 42b of the external water supply pipe 42 to the pipe main body. 22a. Thereafter, the circulation of this cooling water is the same as in the first embodiment described above. In parallel with this, the cooling water in the cooling water passage 7b flows into the cooling water passage 3b in the cylinder cover 3 via the circumferential groove 7c, and flows through the joint portion 43b of the external water supply pipe 43 from the cooling water passage 3b. It flows into the pipe body 23a through the passage 43ba. Thereafter, the circulation of this cooling water is the same as in the first embodiment described above.

Further, in the second embodiment, the external water supply pipes 42, 43 each have a stress absorption structure that absorbs the stress generated in the external water supply pipes 42, 43 due to thermal expansion of the exhaust valve box 10A. Although not shown, each of the stress absorbing structures of the external water supply pipes 42 and 43 has the structure described above, except that the inflow ends of the pipe bodies 22a and 23a are joined to the upper portion of the cylinder cover 3 by joints 42b and 43b. It is the same as the first embodiment. For example, in the stress absorbing structure of the external water supply pipe 42, between the joint 42b and the inflow end of the pipe body 22a, there is a thermal expansion direction F1 (see FIG. 4) of the inflow end of the pipe body 22a with respect to the joint 42b. An O-ring (not shown) is provided to allow sliding. In the stress absorption structure of the external water supply pipe 43, the inflow end of the pipe main body 23a can slide with respect to the joint 43b in the thermal expansion direction F1 between the joint 43b and the inflow end of the pipe main body 23a. An O-ring (not shown) is provided. Alternatively, similar to the stress absorbing structure (see FIG. 5) according to the modified example described above, the stress absorbing structure of the external water supply pipe 42 is a pipe having a variable structure that allows expansion and contraction of the external water supply pipe 42 in the thermal expansion direction F1. It may be constituted by the main body 22a. Similarly, the stress absorption structure of the external water supply pipe 43 may be constituted by the pipe body 23a having a variable structure that allows the external water supply pipe 43 to expand and contract in the thermal expansion direction F1.

As described above, in the cooling structure according to the second embodiment of the present invention, the inflow end of the external water supply pipe 42 is connected by the joint 42b so that the cooling water passage 3a in the cylinder cover 3 and the pipe main body 22a communicate with each other. The inflow end of the external water supply pipe 43 is joined to the upper portion of the cylinder cover 3 by a joint portion 43b so that the cooling water passage 3b in the cylinder cover 3 and the pipe main body 23a communicate with each other. is the same as that of the first embodiment described above. Therefore, it is possible to realize a cooling structure that enjoys the same effects as those of the first embodiment described above, even though the inflow ends of the external water supply pipes 42 and 43 are joined to the upper portion of the cylinder cover 3 .

(Embodiment 3)
Next, a cooling structure according to Embodiment 3 of the present invention will be described. FIG. 7 is a schematic cross-sectional view showing one configuration example of a cooling structure according to Embodiment 3 of the present invention. A marine diesel engine in Embodiment 3 includes an exhaust valve box 10B shown in FIG. 7 instead of the exhaust valve box 10A in Embodiment 2 described above. As shown in FIG. 7, the exhaust valve box 10B includes external water supply pipes 52 and 53 instead of the external water supply pipes 42 and 43 in the second embodiment described above. The cooling structure according to the third embodiment is a cooling structure for such an exhaust valve box 10B. Other configurations are the same as those of the second embodiment, and the same reference numerals are given to the same components.

In Embodiment 3, the cooling structure of the exhaust valve box 10B includes, for example, as shown in FIG. channels 25a, 25b, 25c.

As shown in FIG. 7, the external water supply pipe 52 is not provided with the joint portion 42b described above, and the inflow end portion 52aa of the external water supply pipe 52 is fitted or screwed into the cooling water passage 3a, and the cylinder cover is closed. 3 is joined to the upper part. Thereby, the pipe main body 22 a of the external water supply pipe 52 is arranged so as to communicate with the cooling water passage 3 a inside the cylinder cover 3 . The configuration of the external water supply pipe 52 is the same as that of the external water supply pipe 42 in Embodiment 2, except that the inflow end portion 52aa is joined to the upper portion of the cylinder cover 3 as described above.

As shown in FIG. 7, the external water supply pipe 53 is not provided with the joint portion 43b described above, and the inflow end portion 53aa of the external water supply pipe 53 is fitted or screwed into the cooling water passage 3b so that the cylinder cover is closed. 3 is joined to the upper part. Thereby, the pipe main body 23 a of the external water supply pipe 53 is arranged to communicate with the cooling water passage 3 b inside the cylinder cover 3 . The configuration of the external water supply pipe 53 is the same as that of the external water supply pipe 43 in Embodiment 2, except that the inflow end 53aa is joined to the upper portion of the cylinder cover 3 as described above.

In the cooling structure according to the third embodiment, the cooling water flows into the cooling water passage 7b inside the exhaust valve seat 7 from a lower channel (not shown) inside the cylinder cover 3, for example. The cooling water in the cooling water passage 7b flows through the circumferential groove 7c into the cooling water passage 3a in the cylinder cover 3, and flows into the pipe main body 22a of the external water supply pipe 52 through the cooling water passage 3a. Thereafter, the circulation of this cooling water is the same as in the second embodiment described above. In parallel with this, the cooling water in the cooling water passage 7b flows through the circumferential groove 7c into the cooling water passage 3b in the cylinder cover 3, and flows into the pipe main body 23a of the external water supply pipe 53 through the cooling water passage 3b. . Thereafter, the circulation of this cooling water is the same as in the second embodiment described above.

Further, in the third embodiment, the external water supply pipes 52, 53 each have a stress absorption structure that absorbs stress generated in the external water supply pipes 52, 53 due to thermal expansion of the exhaust valve box 10B. Although not shown, each stress absorbing structure of the external water supply pipes 52 and 53 has its inflow ends 52aa and 53aa joined to the upper portion of the cylinder cover 3 by fitting or screwing into the cooling water passages 3a and 3b. , is the same as the second embodiment described above. For example, in the stress absorption structure of the external water supply pipe 52, the thermal expansion direction F1 (see FIG. 4) of the inflow end 52aa with respect to the cooling water channel 3a can be slid between the cooling water channel 3a and the inflow end 52aa. An O-ring (not shown) is provided. In the stress absorbing structure of the external water supply pipe 53, an O-ring (not shown) is provided between the cooling water passage 3b and the inflow end 53aa to allow the inflow end 53aa to slide with respect to the cooling water passage 3b in the thermal expansion direction F1. ) is provided. Alternatively, similar to the stress absorbing structure (see FIG. 5) according to the modified example described above, the stress absorbing structure of the external water supply pipe 52 is a pipe having a variable structure that allows expansion and contraction of the external water supply pipe 52 in the thermal expansion direction F1. It may be constituted by the main body 22a. Similarly, the stress absorption structure of the external water supply pipe 53 may be constituted by the pipe body 23a having a variable structure that allows the external water supply pipe 53 to expand and contract in the thermal expansion direction F1.

As described above, in the cooling structure according to the third embodiment of the present invention, the inflow end portion 52aa of the external water supply pipe 52 is fitted or screwed so that the cooling water passage 3a in the cylinder cover 3 and the pipe main body 22a communicate with each other. The inflow end 53aa of the external water supply pipe 53 is inserted into the cooling water passage 3b by fitting or screwing so that the cooling water passage 3b in the cylinder cover 3 and the pipe main body 23a communicate with each other. are joined, and other configurations are the same as those of the above-described second embodiment. Therefore, a cooling structure is realized in which the inflow ends 52aa and 53aa of the external water supply pipes 52 and 53 are directly joined to the upper portion of the cylinder cover 3, but which enjoys the same effects as those of the second embodiment. be able to.

(Embodiment 4)
Next, a cooling structure according to Embodiment 4 of the present invention will be described. FIG. 8 is a schematic cross-sectional view showing one configuration example of a cooling structure according to Embodiment 4 of the present invention. A marine diesel engine in Embodiment 4 includes an exhaust valve box 10C shown in FIG. 8 instead of the exhaust valve box 10A in Embodiment 2 described above. As shown in FIG. 8, the exhaust valve box 10C has a circumferential groove 7c at the lower end of its outer wall. The cooling water passages 3a, 3b of the cylinder cover 3 and the cooling water passage 7b of the exhaust valve seat 7 are formed to communicate with each other through the circumferential groove 7c of the exhaust valve box 10C. The cooling structure according to the fourth embodiment is a cooling structure for such an exhaust valve box 10C. Other configurations are the same as those of the second embodiment, and the same reference numerals are given to the same components.

In the fourth embodiment, the cooling structure of the exhaust valve box 10C includes, for example, as shown in FIG. 21 and internal channels 25a, 25b, 25c.

As shown in FIG. 8, the circumferential groove 7c in Embodiment 4 is formed at the lower end corner of the outer wall portion of the exhaust valve box 10C. Specifically, the circumferential groove 7c is formed in a rectangular annular shape along each boundary between the cylinder cover 3, the exhaust valve seat 7, and the exhaust valve box 10C so as to surround the exhaust port 7a. The circumferential groove 7c communicates the one cooling water passage 3a of the cylinder cover 3 with the cooling water passage 7b of the exhaust valve seat 7, and communicates the other cooling water passage 3b of the cylinder cover 3 with the cooling water passage 7b of the exhaust valve seat 7. Let

In the cooling structure according to the fourth embodiment, for example, cooling water flows into the cooling water passage 7b inside the exhaust valve seat 7 from a lower channel (not shown) inside the cylinder cover 3 . The cooling water in the cooling water passage 7b flows through the circumferential groove 7c of the exhaust valve box 10C into the cooling water passage 3a in the cylinder cover 3, and flows from the cooling water passage 3a into the joint portion 42b of the external water supply pipe 42. 42ba into the tube body 22a. Thereafter, the circulation of this cooling water is the same as in the second embodiment described above. In parallel with this, the cooling water in the cooling water passage 7b flows through the circumferential groove 7c of the exhaust valve box 10C into the cooling water passage 3b in the cylinder cover 3, and the external water supply pipe 43 is joined from this cooling water passage 3b. It flows into the pipe main body 23a through the flow passage 43ba in the portion 43b. Thereafter, the circulation of this cooling water is the same as in the second embodiment described above.

As described above, in the cooling structure according to the fourth embodiment of the present invention, the circumferential groove 7c is formed at the lower end corner of the outer wall portion of the exhaust valve box 10C, and the cooling inside the cylinder cover 3 is performed via this circumferential groove 7c. The water passages 3a, 3b and the cooling water passage 7b in the exhaust valve seat 7 are made to communicate with each other, and the rest of the configuration is the same as that of the second embodiment. For this reason, although the circumferential groove 7c that communicates the cooling water passages 3a and 3b in the cylinder cover 3 with the cooling water passage 7b in the exhaust valve seat 7 is formed at the bottom corner of the outer wall portion of the exhaust valve box 10C, It is possible to realize a cooling structure that enjoys the same effects as those of the second embodiment described above.

In the first to fourth embodiments described above, the internal flow path that communicates between the cooling chamber 21 and the external water supply pipe above the exhaust port 10a in the exhaust valve boxes 10, 10A, 10B, and 10C is formed in the cooling chamber 21. The internal flow path merges with the cooling chamber 21 along the circumferential direction, or the internal flow path merges with the cooling chamber 21 on the opposite side of the cooling water outlet 26 across the cooling chamber 21. However, the present invention is not limited to this. is not limited to For example, the internal flow path that communicates the cooling chamber 21 and the external water supply pipe above the exhaust port 10a in the exhaust valve boxes 10, 10A, 10B, and 10C is arranged opposite to the cooling water outlet 26 with the cooling chamber 21 interposed therebetween. It is good also as an internal flow path which merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21 on the side.

Further, in the first to fourth embodiments described above, the inflow end and outflow end of the pipe body 23a of the external water supply pipes 23, 43, 53 are connected to the joints 23b, 23c, 43b or the cooling water passage 3b in the cylinder cover 3. Although the stress-absorbing structure in which each free end is provided as an example, the present invention is not limited to this. For example, the stress absorption structure of the external water supply pipe 23 is such that the inflow end 23aa of the pipe main body 23a is a free end with respect to the joint 23b, and the outflow end 23ab of the pipe main body 23a is fixed with respect to the joint 23c. Alternatively, the inflow end 23aa of the pipe main body 23a may be a fixed end with respect to the joint 23b, and the outflow end 23ab of the pipe main body 23a may be a free end with respect to the joint 23c. good too. The same applies to the external water supply pipes 43 and 53 as well. The stress absorption structure of the external water supply pipe 22 is such that the inflow end of the pipe main body 22a is a fixed end with respect to the joint 22b and the outflow end of the pipe main body 22a is a free end with respect to the joint 22c. Alternatively, the inflow end and the outflow end of the pipe body 22a may be free ends with respect to the joints 23b and 23c. The same applies to the external water supply pipes 42 and 52 as well.

Further, in the first to fourth embodiments described above, the opening end (cooling water outlet 26) of the internal flow path 25b was exemplified as the outlet of the cooling water in the cooling chamber 21, but the present invention is limited to this. isn't it. For example, the cooling water outlet in the cooling chamber 21 may be formed at a location other than the cooling water outlet 26 described above.

Moreover, in the first to fourth embodiments described above, the case where two external water supply pipes are joined to the outer wall portion of the exhaust valve box or the like is illustrated, but the present invention is not limited to this. The number of external water supply pipes connected to the outer wall of the exhaust valve box or the like may be one or plural (two or more).

In addition, in the modified example described above, a curved pipe body was exemplified as a pipe body having a variable structure that enables expansion and contraction of the external water supply pipe in the thermal expansion direction, but the present invention is not limited to this. . For example, the variable-structure pipe body may be a pipe body having a bellows structure that can be expanded and contracted in the thermal expansion direction of the external water supply pipe, or a pipe body having a structure in which a plurality of cylindrical bodies are slidably fitted together. There may be.

In addition, the present invention is not limited by the first to fourth embodiments and modified examples described above, and the present invention also includes configurations obtained by appropriately combining the respective constituent elements described above. In addition, other embodiments, examples, operation techniques, etc. made by those skilled in the art based on the above-described Embodiments 1 to 4 are all included in the scope of the present invention.

1 Marine Diesel Engine 2 Cylinder Liner 3 Cylinder Cover 3a, 3b Cooling Channel 4 Piston 5 Piston Rod 6 Exhaust Valve 6a Valve Body 6b Valve Stem 7 Exhaust Valve Seat 7a Exhaust Port 7b Cooling Channel 7c Circumferential Groove 8 Combustion Chamber 9 Fuel Injection Valve 10 , 10A, 10B, 10C Exhaust valve box 10a Exhaust port 11 Valve stem guide 12 Cover 13 Exhaust valve actuator 14 Connection pipe 15 Exhaust manifold 21 Cooling chamber 22, 23, 33, 42, 43, 52, 53 External water supply pipe 22a , 23a, 33a pipe main body 22b, 22c, 23b, 23c, 42b, 43b junction 22ba, 23ba, 23ca, 42ba, 43ba flow path 23aa, 33aa, 52aa, 53aa inflow end 23ab, 33ab outflow end 23bb, 23cb engagement Joint portions 24a, 24b Lower passages 25a, 25b, 25c Internal passages 26 Cooling water outlets 27a, 27b O-ring F1 Thermal expansion direction

Claims (6)

An exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine, and a valve stem guide section for guiding the sliding of the valve stem of the exhaust valve that opens and closes between the combustion chamber and the exhaust gas path. A cooling structure for an exhaust valve box comprising:
a cooling chamber formed above the exhaust gas path in the exhaust valve box so as to surround the outer periphery of the valve stem guide portion and for cooling the valve stem guide portion with cooling water;
an external water supply pipe that is piped so as to communicate with the cooling chamber above the exhaust gas path through the outside from the lower side of the exhaust valve box, and supplies the cooling water to the cooling chamber;
with
The external water supply pipe has a stress absorption structure that absorbs stress generated in the external water supply pipe due to thermal expansion of the exhaust valve box,
The stress absorbing structure includes:
a joint portion that joins the end portion of the pipe body of the external water supply pipe to the outer wall portion of the exhaust valve box;
a sliding member that enables the end portion of the pipe body to slide with respect to the joint portion in the thermal expansion direction;
A cooling structure comprising : An exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine, and a valve stem guide section for guiding the sliding of the valve stem of the exhaust valve that opens and closes between the combustion chamber and the exhaust gas path. A cooling structure for an exhaust valve box comprising:
a cooling chamber formed above the exhaust gas path in the exhaust valve box so as to surround the outer periphery of the valve stem guide portion and for cooling the valve stem guide portion with cooling water;
an external water supply pipe that is piped so as to communicate with the cooling chamber above the exhaust gas path through the outside from the lower side of the exhaust valve box, and supplies the cooling water to the cooling chamber;
with
The external water supply pipe has a stress absorption structure that absorbs stress generated in the external water supply pipe due to thermal expansion of the exhaust valve box,
The stress absorbing structure includes:
a joint for joining the end of the pipe body of the external water supply pipe to the upper part of the cylinder cover positioned below the exhaust valve box;
a sliding member that enables the end portion of the pipe body to slide with respect to the joint portion in the thermal expansion direction;
A cooling structure comprising: An exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine, and a valve stem guide section for guiding the sliding of the valve stem of the exhaust valve that opens and closes between the combustion chamber and the exhaust gas path. A cooling structure for an exhaust valve box comprising:
a cooling chamber formed above the exhaust gas path in the exhaust valve box so as to surround the outer periphery of the valve stem guide portion and for cooling the valve stem guide portion with cooling water;
an external water supply pipe that is piped so as to communicate with the cooling chamber above the exhaust gas path through the outside from the lower side of the exhaust valve box, and supplies the cooling water to the cooling chamber;
with
The external water supply pipe has a stress absorption structure that absorbs stress generated in the external water supply pipe due to thermal expansion of the exhaust valve box,
The stress absorbing structure includes:
provided between the end of the pipe main body of the external water supply pipe joined to the upper part of the cylinder cover so as to communicate with the cooling water passage in the cylinder cover located below the exhaust valve box and the cooling water passage, A cooling structure comprising a sliding member that allows the end of the pipe body to slide with respect to the cooling water passage in a thermal expansion direction. An internal flow path formed above the exhaust gas path in the exhaust valve box and joining the cooling chamber along the circumferential direction of the cooling chamber,
The cooling structure according to any one of claims 1 to 3 , wherein the external water supply pipe communicates with the cooling chamber through the internal channel. An internal flow path formed above the exhaust gas path in the exhaust valve box and merging with the cooling chamber on the opposite side of the cooling water outlet across the cooling chamber,
The cooling structure according to any one of claims 1 to 3 , wherein the external water supply pipe communicates with the cooling chamber through the internal channel. The cooling structure according to any one of claims 1 to 5 , wherein a plurality of said external water supply pipes are arranged.

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