CN113167192A - Cooling structure - Google Patents

Cooling structure Download PDF

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Publication number
CN113167192A
CN113167192A CN201980075774.1A CN201980075774A CN113167192A CN 113167192 A CN113167192 A CN 113167192A CN 201980075774 A CN201980075774 A CN 201980075774A CN 113167192 A CN113167192 A CN 113167192A
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CN
China
Prior art keywords
cooling
exhaust valve
water supply
external water
supply pipe
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201980075774.1A
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Chinese (zh)
Inventor
木下芳彦
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Japan Engine Corp
Original Assignee
Japan Engine Corp
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Filing date
Publication date
Application filed by Japan Engine Corp filed Critical Japan Engine Corp
Publication of CN113167192A publication Critical patent/CN113167192A/en
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/12—Cooling of valves
    • F01L3/14—Cooling of valves by means of a liquid or solid coolant, e.g. sodium, in a closed chamber in a valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/12—Cooling of valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P11/00—Component parts, details, or accessories not provided for in, or of interest apart from, groups F01P1/00 - F01P9/00
    • F01P11/04—Arrangements of liquid pipes or hoses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/12—Arrangements for cooling other engine or machine parts
    • F01P3/14—Arrangements for cooling other engine or machine parts for cooling intake or exhaust valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F1/26—Cylinder heads having cooling means
    • F02F1/36—Cylinder heads having cooling means for liquid cooling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F1/26—Cylinder heads having cooling means
    • F02F1/36—Cylinder heads having cooling means for liquid cooling
    • F02F1/38—Cylinder heads having cooling means for liquid cooling the cylinder heads being of overhead valve type
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Exhaust Silencers (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)

Abstract

A cooling structure according to an aspect of the present invention is used for an exhaust valve box having: an exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine; and a valve rod guide portion for guiding sliding of a valve rod of an exhaust valve that opens and closes between the combustion chamber and the exhaust gas path, the cooling structure including: a cooling chamber for cooling the valve stem guide by cooling water; and an external water supply pipe that supplies the cooling water to the cooling chamber. The cooling chamber is formed in an upper portion of the exhaust valve box with respect to the exhaust gas passage so as to surround an outer periphery of the stem guide. The external water supply pipe is disposed so as to communicate with the cooling chamber through an outer side from a lower side of the exhaust valve box and above the exhaust gas passage.

Description

Cooling structure
Technical Field
The present invention relates to a cooling structure for an exhaust valve box of a marine diesel engine.
Background
Conventionally, a cooling structure for a marine diesel engine mounted on a ship has been disclosed. For example, in the cooling structure described in patent document 1, cooling water is supplied from the lower edge portion of the cylinder head, and the supplied cooling water flows to the upper portion of the cylinder head through a flow path in the cylinder head. Thereby, the cylinder head and the structure above the cylinder head can be cooled by the cooling water.
In a marine diesel engine, an exhaust valve housing is provided above a cylinder cover. Generally, an exhaust port, which is an exhaust path for discharging exhaust gas from a combustion chamber of a gas cylinder (cylinder), is formed in an exhaust valve housing. In the exhaust valve box, a valve rod of the exhaust valve that opens and closes between the combustion chamber and the exhaust port is slidably supported by a rod guide portion that guides the sliding of the valve rod.
In order to maintain smooth sliding of the valve stem in the valve stem guide portion, it is necessary to supply lubricating oil to the valve stem guide portion, and to appropriately form a film of lubricating oil between these valve stem guide portion and the valve stem. However, in the exhaust valve box, heat of the high-temperature exhaust gas flowing through the exhaust port is transferred to the valve rod guide portion, and thus the temperature of the valve rod guide portion may excessively rise. In this case, the viscosity of the lubricating oil supplied to the valve stem guide portion decreases, and the valve stem guide portion becomes in a state in which it is difficult to hold a film of the lubricating oil with the valve stem, that is, a state in which the lubricating oil is in a shortage. This state becomes a cause of the valve rod guide portion to prevent smooth sliding of the valve rod.
In order to avoid the oil shortage state, a cooling chamber is formed in the vicinity of the valve rod guide portion in the exhaust valve housing. In addition, a flow path from the lower cylinder cover side to the upper cooling chamber side is formed in the side wall of the exhaust valve box. The valve stem guide is cooled by the cooling water flowing into the cooling chamber through the flow path. Thus, excessive temperature rise of the valve stem guide is suppressed.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 10-54240
Technical problem to be solved by the invention
However, in the above-described exhaust valve box, since the flow path of the cooling water 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, and the temperature of the exhaust gas in the exhaust port may be excessively lowered. As a result, sulfuric acid is generated from the exhaust gas in the exhaust port, and the inside of the exhaust valve box is corroded by the sulfuric acid.
Disclosure of Invention
The present invention has been made in view of the above circumstances, and an object thereof is to provide a cooling structure capable of cooling a valve rod guide portion provided in an exhaust valve box while suppressing occurrence of sulfuric acid corrosion in the exhaust valve box.
Means for solving the problems
In order to solve the above-described problems and achieve the object, a cooling structure according to the present invention is used for an exhaust valve box having: an exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine; and a valve rod guide portion for guiding sliding of a valve rod of an exhaust valve that opens and closes between the combustion chamber and the exhaust gas path, the cooling structure including: a cooling chamber formed in an upper portion of the exhaust valve housing with respect to the exhaust gas passage so as to surround an outer periphery of the valve rod guide, the cooling chamber being configured to cool the valve rod guide with cooling water; and an external water supply pipe that is disposed so as to communicate with the cooling chamber from a lower side of the exhaust valve box through an outer side thereof and on an upper side of the exhaust gas passage, and that supplies the cooling water to the cooling chamber.
In the cooling structure of the present invention, in the above-described invention, the external water supply pipe includes a stress absorbing structure that absorbs stress generated in the external water supply pipe in accordance with thermal expansion of the exhaust valve box.
In the above-described cooling structure of the present invention, the stress absorbing structure includes a joint portion that joins an end portion of the pipe main body of the external water supply pipe to an outer wall portion of the exhaust valve box, and a sliding member that enables the end portion of the pipe main body to slide in a thermally elongated direction with respect to the joint portion.
In the above-described cooling structure of the present invention, the stress absorbing structure includes a joint portion that joins an end portion of the pipe main body of the external water supply pipe to an upper portion of the cylinder head located below the exhaust valve box, and a slide member that enables the end portion of the pipe main body to slide in a thermally-elongated direction with respect to the joint portion.
In the cooling structure of the present invention, in the above-described invention, the stress absorbing structure is constituted by a tube main body having a variable structure that is capable of expanding and contracting in a thermal expansion direction of the external water supply tube.
In the above-described invention, the cooling structure of the present invention includes an internal flow path formed in an upper portion of the exhaust valve box with respect to the exhaust gas path and merging with the cooling chamber along a circumferential direction of the cooling chamber, and the external water supply pipe communicates with the cooling chamber through the internal flow path.
In the above-described invention, the cooling structure of the present invention includes an internal flow path formed in an upper portion of the exhaust valve box with respect to the exhaust gas path and merging with the cooling chamber on a side opposite to the cooling chamber with the cooling water outlet interposed therebetween, and the external water supply pipe communicates with the cooling chamber through the internal flow path.
In the cooling structure of the present invention, in the above invention, a plurality of external water supply pipes are provided.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, the valve rod guide portion provided in the exhaust valve box can be cooled while suppressing the occurrence of sulfuric acid corrosion in the exhaust valve box.
Drawings
Fig. 1 is a schematic diagram showing an example of the structure in 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 a cooling structure according to embodiment 1 of the present invention.
Fig. 3 is a schematic view of the cooling structure of 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 a stress absorbing structure of an external water supply pipe in embodiment 1 of the present invention.
Fig. 5 is a schematic view showing a modification of the stress absorbing structure of the external water supply pipe in embodiment 1 of the present invention.
Fig. 6 is a schematic cross-sectional view showing an example of a cooling structure according to embodiment 2 of the present invention.
Fig. 7 is a schematic cross-sectional view showing an example of a cooling structure according to embodiment 3 of the present invention.
Fig. 8 is a schematic cross-sectional view showing an example of a cooling structure according to embodiment 4 of the present invention.
Detailed Description
Hereinafter, preferred embodiments of the cooling structure of the present invention will be described in detail with reference to the drawings. The present embodiment does not limit the present invention. Note that the drawings are schematic, and it is necessary to note that the relationship in size of each element, the ratio of each element, and the like may be different from the actual ones. In some cases, the drawings include portions having different dimensional relationships and ratios. In the drawings, the same components are denoted by the same reference numerals.
(embodiment mode 1)
(Structure of Diesel Engine for watercraft)
First, a description will be given of a configuration of a marine diesel engine provided with an exhaust valve box having a cooling structure according to embodiment 1 of the present invention. Fig. 1 is a schematic diagram showing an example of the structure in 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 mechanism (main mechanism) that rotates a propulsion propeller (neither shown) of a marine vessel via a propeller shaft. For example, the marine diesel engine 1 is a two-stroke diesel engine such as a one-way scavenging crosshead diesel engine. The marine diesel engine 1 may be a six-cylinder engine, but the number of cylinders is not particularly limited. The operation control method of the marine diesel engine 1 is not particularly limited, and examples thereof include a cam type and an electronic control type.
Further, the structure in the vicinity of the exhaust valve box of the marine diesel engine 1 is the same in any cylinder (cylinder). Therefore, in the following, the structure of the vicinity of the exhaust valve box of the marine diesel engine 1 will be described with respect to one of the cylinders.
As shown in fig. 1, a marine diesel engine 1 includes: the cylinder liner 2, the cylinder cover 3, the piston 4, the piston rod 5, the exhaust valve 6, the exhaust valve seat 7, the fuel injection valve 9, the exhaust valve box 10, the cover 12, the connection pipe 14, and the exhaust manifold 15.
The cylinder liner 2 is a tubular structure, and a cylinder head 3 is attached to an upper portion of the cylinder liner 2. The cylinder liner 2 and the cylinder cover 3 constitute one cylinder in the marine diesel engine 1, and form a cylindrical space (i.e., a space in the cylinder) in which the piston 4 reciprocates. The piston 4 is disposed in the space so as to be movable reciprocally. The upper part of the piston rod 5 is connected to the lower part of the piston 4. Although not particularly shown, the lower portion of the piston rod 5 is coupled to the crankshaft via a cross head or the like. The 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 element 6a and a valve stem 6 b. The exhaust valve seat 7 is assembled to an upper portion of the cylinder cover 3, and is configured such that a valve body 6a of the exhaust valve 6 is seated freely and an exhaust port 7a is formed. The cylinder liner 2, the cylinder cover 3, the piston 4, and the valve body 6a form a combustion chamber 8 in the cylinder. The fuel injection valve 9 is attached to the cylinder cover 3 and configured to be capable of injecting fuel (heavy oil, light oil, etc.) into the combustion chamber 8.
The exhaust valve box 10 is attached to an upper portion of the cylinder (in embodiment 1, an upper portion of the cylinder cover 3 constituting the cylinder). Thus, the lower end of the exhaust valve housing 10 is connected to the upper end of the exhaust valve seat 7 assembled to the upper portion of the cylinder cover 3. An exhaust port 10a communicating with the exhaust port 7a of the exhaust valve seat 7 is formed inside the exhaust valve housing 10. Further, a stem guide 11 is assembled inside the exhaust valve housing 10. The exhaust valve box 10 slidably supports the valve stem 6b of the exhaust valve 6 via a stem guide 11.
The cover 12 is attached to an upper portion of the exhaust valve housing 10, and houses an exhaust valve operating device 13 configured such that the exhaust valve 6 can reciprocate. The exhaust valve operating device 13 includes a biasing member (not shown) such as a compression spring or an air spring therein, and supports the exhaust valve 6 in a state biased in a direction to close the exhaust port 7a by the action of the biasing member. The exhaust valve operating device 13 is connected to a fuel supply pump (not shown) via a pipe. When the working 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 working oil. In this manner, the exhaust valve operating device 13 operates the exhaust valve 6 to open the exhaust port 7 a. The exhaust valve 6 opens the exhaust port 7a only during the supply of the working oil to the exhaust valve operating device 13, and closes the exhaust port 7a when the supply of the working oil is stopped.
The connection pipe 14 connects an exhaust port 10a formed in the exhaust valve box 10 to an 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 connection pipe 14, temporarily retains the received exhaust gas, and changes the dynamic pressure of the exhaust gas to a static pressure.
In the 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 4 is raised, and the exhaust port 7a is closed by the exhaust valve 6, whereby the combustion gas in the combustion chamber 8 is compressed. When the piston 4 moves to the top dead center, the pressure in the combustion chamber 8 becomes 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 piston 4 is lowered by the combustion energy. At a predetermined timing, the exhaust port 7a is opened by the exhaust valve 6, whereby 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. Thereafter, the exhaust gas is discharged from the exhaust port 10a to the exhaust manifold 15 through the connection pipe 14.
(Cooling Structure)
Next, a cooling structure according to embodiment 1 of the present invention will be described. The cooling structure of embodiment 1 is a cooling structure used for the exhaust valve box 10 in the marine diesel engine 1, for example. Fig. 2 is a schematic cross-sectional view showing one configuration example of a cooling structure according to embodiment 1 of the present invention. Fig. 3 is a schematic view of the cooling structure of embodiment 1 of the present invention as viewed from the upper side of the exhaust valve box.
As described above, the exhaust valve housing 10 has the exhaust port 10a and the stem guide 11 therein. The exhaust port 10a is an exhaust gas path for discharging exhaust gas from the combustion chamber 8 of the marine diesel engine 1, and communicates with an exhaust port 7a of an exhaust valve seat 7 communicating with the combustion chamber 8. The valve stem guide 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 (i.e., the exhaust port 7 a). The stem guide 11 is, for example, a cylindrical structure, and is provided inside the exhaust valve box 10 so as to extend from a lower portion of the cover 12 (an upper end portion of the exhaust valve box 10) to an upper portion of the exhaust port 10 a. A valve stem 6b of the exhaust valve 6 is slidably inserted into the valve stem guide 11. The exhaust valve box 10 regulates the sliding direction of the valve rod 6b in a predetermined direction (for example, the vertical direction of the exhaust valve box 10) via the valve rod guide 11, and supports the valve rod 6 b. As shown in fig. 2 and 3, the cooling structure of the exhaust valve box 10 includes: a cooling chamber 21, external water supply pipes 22, 23, lower channels 24a, 24b, and internal channels 25a, 25b, 25 c.
The cooling chamber 21 is a space for cooling the stem guide 11 with cooling water. As shown in fig. 2 and 3, the cooling chamber 21 is formed (for example, in a ring shape) above the exhaust port 10a in the exhaust valve housing 10 so as to surround the outer periphery of the stem guide 11.
The external water supply pipes 22 and 23 are examples of a plurality of external water supply pipes arranged to supply cooling water to the cooling chamber 21. As shown in fig. 2 and 3, the external water supply pipes 22 and 23 are respectively disposed so as to communicate with the cooling chamber 21 from the lower side of the exhaust valve box 10 to the upper side of the exhaust port 10a through the outside. In embodiment 1, the external water supply pipes 22 and 23 each have a stress absorbing structure that absorbs stress generated in the external water supply pipes 22 and 23 in accordance with thermal expansion of the exhaust valve housing 10.
In embodiment 1, for example, as shown in fig. 2, the external water supply pipe 22 includes: a pipe main body 22a for circulating cooling water outside the exhaust valve housing 10, and joining portions 22b and 22c for joining the end portions of the pipe main body 22a to the outer wall portion of the exhaust valve housing 10.
The pipe main body 22a is disposed outside the exhaust valve housing 10 so as to extend from the lower portion to the upper portion of the exhaust valve housing 10, while avoiding contact with the outer wall portion of the exhaust valve housing 10 and a structure protruding from the outer wall portion (for example, a flange portion of the exhaust port 10 a). One end portion (inflow end portion) of the pipe main body 22a is joined to a lower portion of the outer wall portion of the exhaust valve housing 10 by a joint portion 22 b. Examples of the lower portion include an outer wall portion near (preferably, below) an inlet end portion of the exhaust port 10a of the exhaust valve housing 10. The other end (outflow end) of the pipe main body 22a is joined to an upper portion of the outer wall of the exhaust valve housing 10 by a joint portion 22 c. Examples of the upper portion include an outer wall portion located above the exhaust port 10a of the exhaust valve housing 10.
Joint portion 22b has flow passage 22ba therein. The joint portion 22b joins the inflow end portion of the pipe main body 22a to the lower side portion of the outer wall portion of the exhaust valve housing 10 by fastening or the like, and communicates the lower flow path 24a of the exhaust valve housing 10 with the pipe main body 22a via the flow passage 22 ba. On the other hand, the joint portion 22c joins the outflow end portion of the pipe main body 22a to the upper portion of the outer wall portion of the exhaust valve housing 10 by fastening or the like to communicate the internal flow path 25a of the upper portion of the exhaust valve housing 10 with the pipe main body 22 a.
In embodiment 1, for example, as shown in fig. 2, the external water supply pipe 23 is disposed on the opposite side of the external water supply pipe 22 from the exhaust valve box 10. The external water supply pipe 23 includes: a pipe main body 23a for circulating cooling water outside the exhaust valve housing 10, and joining portions 23b and 23c for joining the end of the pipe main body 23a to the outer wall of the exhaust valve housing 10.
On the side opposite to the side of the pipe main body 22a across the exhaust valve housing 10, the pipe main body 23a is disposed outside the exhaust valve housing 10 so as to extend from the lower portion to the upper portion of the exhaust valve housing 10 while avoiding contact with the outer wall portion of the exhaust valve housing 10 and a structure protruding from the outer wall portion. One end portion (inflow end portion) of the pipe main body 23a is joined to a lower side portion of the outer wall portion of the exhaust valve housing 10 by a joint portion 23 b. The other end portion (outflow end portion) of the pipe main body 23a is joined to an upper side portion of the outer wall portion of the exhaust valve housing 10 by a joining portion 23 c.
The joint portion 23b has a flow passage 23ba therein. On the side opposite to the joint portion 22b with the exhaust valve box 10 interposed therebetween, the joint portion 23b joins the inflow end portion of the pipe main body 23a to the lower portion of the outer wall portion of the exhaust valve box 10 by fastening or the like, and communicates the lower flow passage 24b of the exhaust valve box 10 with the pipe main body 23a via the flow passage 23 ba. The joint portion 23c has a flow passage 23ca therein. On the opposite side of the exhaust valve box 10 from the joint portion 22c, the joint portion 23c joins the outflow end portion of the pipe main body 23a to the upper portion of the outer wall portion of the exhaust valve box 10 by fastening or the like, and communicates the internal flow passage 25c of the upper portion of the exhaust valve box 10 with the pipe main body 23a via the flow passage 23 ca.
As shown in fig. 2, lower flow passages 24a and 24b are formed in the lower side in the outer wall portion of the exhaust valve housing 10. The lower flow passages 24a and 24b are formed in the lower portion of the inside of the outer wall portion of the exhaust valve housing 10 such that one end portions thereof open to the lower end surface of the outer wall portion of the exhaust valve housing 10 and the other end portions thereof open to the side wall surface of the outer wall portion of the exhaust valve housing 10. Here, as shown in fig. 2, a cooling water passage 7b is formed inside the exhaust valve seat 7, and this cooling water passage 7b extends from the joint end surface side of the exhaust valve seat 7 and the exhaust valve box 10 to the contact portion (seating portion) of the exhaust valve seat 7 and the valve body 6a of the exhaust valve 6. The cooling water passage 7b supplies cooling water through a flow passage (not shown) formed in the cylinder cover 3, for example. The cooling water supplied to the cooling water passage 7b cools the exhaust valve seat 7 (particularly, the seat portion).
As shown in fig. 2, a circumferential groove 7c is formed between the cooling water passage 7b of the exhaust valve seat 7 and the lower flow passages 24a and 24b of the exhaust valve housing 10. For example, the circumferential groove 7c is formed in a circular or rectangular ring shape along a boundary portion between the exhaust valve seat 7 and the exhaust valve housing 10 so as to surround the exhaust port 7 a. The circumferential groove 7c is formed in at least one of the exhaust valve seat 7 and the exhaust valve housing 10. In embodiment 1, the exhaust valve seat 7 and the exhaust valve box 10 are provided at their respective end portions across the boundary portion 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 lower flow passages 24a and 24b through the circumferential groove 7 c. That is, one lower flow path 24a communicates cooling water path 7b with flow passage 22ba in joint 22b via circumferential groove 7c, and the other lower flow path 24b communicates cooling water path 7b with flow passage 23ba in joint 23b via circumferential groove 7 c.
As shown in fig. 2, internal flow passages 25a, 25b, and 25c are formed in the exhaust valve box 10 at an upper portion of the exhaust port 10 a. Of these internal passages 25a, 25b, 25c, the internal passages 25a, 25b communicate one external water supply pipe 22 with the cooling chamber 21, and the internal passage 25c communicates the other external water supply pipe 23 with the cooling chamber 21.
Specifically, as shown in fig. 2 and 3, the internal flow passage 25a is formed at an upper portion of the exhaust port 10a such that one end portion thereof opens on the side wall surface of the outer wall portion of the exhaust valve housing 10 and the other end portion thereof is connected to a middle portion of the internal flow passage 25 b. The external water supply pipe 22 joined to the outer wall portion of the exhaust valve box 10 as described above communicates with the internal flow passage 25b on the upper side of the exhaust port 10a in the internal flow passage 25 a. On the other hand, the internal flow passage 25b is formed above the exhaust port 10a so that one end is connected to the cooling chamber 21 and the other end is open to the upper end surface of the exhaust valve housing 10. As shown in fig. 2 and 3, the opening of the internal flow passage 25b constitutes a cooling water outlet 26. As described above, the internal flow path 25b is connected to the internal flow path 25a at a middle portion thereof. The internal flow passage 25b communicates the internal flow passage 25a, which communicates with the external water supply pipe 22 as described above, with the cooling chamber 21 on the upper side of the exhaust port 10 a.
In embodiment 1, for example, as shown in fig. 3, the internal flow path 25b merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21. The external water supply pipe 22 communicates with the cooling chamber 21 through the internal flow passages 25a and 25 b. That is, the internal flow passages 25a and 25b communicate the cooling chamber 21 with the external water supply pipe 22 on the upper side of the exhaust port 10a, and constitute an internal flow passage that merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21.
On the other hand, as shown in fig. 2 and 3, the internal flow passage 25c is formed in an upper portion of the exhaust port 10a such that one end portion thereof opens on the side wall surface of the outer wall portion of the exhaust valve housing 10 and the other end portion thereof is connected to the cooling chamber 21. The internal flow passage 25c communicates the external water supply pipe 23 joined to the outer wall portion of the exhaust valve box 10 as described above with the cooling chamber 21 on the upper side of the exhaust port 10 a. In embodiment 1, for example, as shown in fig. 2 and 3, the internal flow path 25c merges with the cooling chamber 21 on the side opposite to the cooling water outlet 26 across the cooling chamber 21. The external water supply pipe 23 communicates with the cooling chamber 21 through the internal flow passage 25c on the side opposite to the external water supply pipe 22 with the exhaust valve box 10 interposed therebetween. Further, "the side opposite to the cooling water outlet 26 across the cooling chamber 21" indicates: the positional relationship between the internal flow path 25c and the cooling water outlet 26 is: for example, in a plan view of the exhaust valve housing 10 viewed from above as shown in fig. 3, a line segment connecting the center point of the merging portion of the internal flow passage 25c and the cooling chamber 21 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 in the exhaust valve seat 7 from, for example, a flow passage (not shown) in the cylinder cover 3. The cooling water in the cooling water passage 7b flows into a lower flow passage 24a in the outer wall portion of the exhaust valve housing 10 through the circumferential groove 7c, and is guided from the lower flow passage 24a to an upper portion of the exhaust port 10a in the exhaust valve housing 10 through the external water supply pipe 22. Specifically, the cooling water flows from the lower flow path 24a through the flow passage 22ba in the joint portion 22b of the external water supply pipe 22 into the pipe main body 22a, and flows through the pipe main body 22a into the internal flow path 25a of the exhaust valve box 10. Then, the cooling water flows into the cooling chamber 21 through the internal flow passage 25b from the internal flow passage 25a on the upper side of the exhaust port 10a in the exhaust valve housing 10.
In parallel with this, the cooling water in the cooling water passage 7b flows into the lower flow passage 24b in the outer wall portion of the exhaust valve housing 10 through the circumferential groove 7c, and is guided from the lower flow passage 24b to the upper portion of the exhaust port 10a in the exhaust valve housing 10 through the external water supply pipe 23. Specifically, the cooling water flows from the lower flow path 24b through the flow passage 23ba in the joint portion 23b of the external water supply pipe 23 into the pipe main body 23a, and flows through the pipe main body 23a and the flow passage 23ca in the joint portion 23c in this order into the internal flow path 25c of the exhaust valve box 10. Then, the cooling water flows into the cooling chamber 21 through the internal flow path 25c on the upper side of the exhaust port 10a in the exhaust valve housing 10.
The cooling water flowing into the cooling chamber 21 as described above flows through the cooling chamber 21, and cools the stem guide 11 via the wall of the cooling chamber 21. For example, as shown in fig. 3, since the internal flow passage 25b is a flow passage that merges with the cooling chamber 21 in the circumferential direction of the cooling chamber 21, the cooling water supplied from the external water supply pipe 22 to the cooling chamber 21 through the internal flow passages 25a and 25b flows in the circumferential direction in the cooling chamber 21. This suppresses the retention of the cooling water in the cooling chamber 21, and the cooling water circulates in the cooling chamber 21, exchanges with the newly supplied cooling water, and is discharged from the cooling water outlet 26. Further, as shown in fig. 3, since the internal flow path 25c is a flow path that joins the cooling chamber 21 on the opposite side of the cooling water outlet 26 from the cooling chamber 21, the flow path of the cooling water in the cooling chamber 21 from the joining portion of the internal flow path 25c and the cooling chamber 21 to the cooling water outlet 26 is longer than in the case where the cooling water outlet 26 is on the same side. Thus, the cooling water supplied from the external water supply pipe 23 to the cooling chamber 21 through the internal flow path 25c flows a long distance in the cooling chamber 21 until being discharged from the cooling water outlet 26.
When the cooling water flowing through the cooling chamber 21 cools the valve rod guide 11 as described above, the cooling water in the cooling chamber 21 removes heat transferred from the exhaust gas in the exhaust port 10a to the valve rod guide 11, and thus suppresses a temperature increase of the valve rod guide 11. Here, lubricating oil for smoothing the sliding of the valve stem 6b in the valve stem guide portion 11 is supplied between the valve stem guide portion 11 and the valve stem 6b of the exhaust valve 6. The lubricating oil is interposed between the stem guide 11 and the stem 6b to form an oil film. As described above, since the valve rod guide 11 is cooled by the cooling water in the cooling chamber 21, the lubricating oil has an appropriate viscosity and retains the oil film. This maintains smooth sliding of the valve stem 6b in the stem guide 11. The cooling water for cooling the stem guide 11 passes through the cooling chamber 21, the internal flow path 25b, and reaches the cooling water outlet 26, and is discharged from the cooling water outlet 26 to the outside of the exhaust valve box 10 through a pipe or the like (not shown).
(stress absorbing Structure of external Water supply pipe)
Next, a stress absorbing structure of an 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 be thermally elongated by the heat of the high-temperature exhaust gas discharged from the combustion chamber 8 to the exhaust port 10 a. As shown in fig. 2 and 3, stress (for example, tensile stress) may be generated in the external water supply pipes 22 and 23 joined to the outer wall portion of the exhaust valve housing 10 as the exhaust valve housing 10 is stretched due to thermal elongation. In order to prevent the external water supply pipes 22 and 23 from being damaged by the stress, the external water supply pipes 22 and 23 have a stress absorbing structure that absorbs the stress.
Fig. 4 is a schematic cross-sectional view showing an example of a stress absorbing structure of an external water supply pipe in embodiment 1 of the present invention. Fig. 4 illustrates a stress absorbing structure of the external water supply pipe 23 as an example of the stress absorbing structure.
As shown in fig. 4, in the external water supply pipe 23, the joint portion 23b includes therein: the flow passage 23ba and the engagement portion 23bb communicating with the flow passage 23 ba. The inflow end portion 23aa of the tube main body 23a is fitted into the engagement portion 23bb of the joint portion 23 b. Thereby, inflow end portion 23aa is engaged with engagement portion 23bb, and tube main body 23a communicates with flow passage 22ba in joint portion 23 b. Further, an O-ring 27a is interposed between the inflow end portion 23aa and the engagement portion 23 bb. The O-ring 27a is an example of a sliding member that allows the end portion (the inflow end portion 23aa in fig. 4) of the tube main body 23a to slide in the thermal expansion direction F1 with respect to the joint portion 23 b. The tube main body 23a is connected to the joint portion 23b such that the inflow end portion 23aa is slidable in the thermal expansion direction F1 with respect to the engagement portion 23bb via the O-ring 27 a. That is, the inflow end portion 23aa of the tube main body 23a is a free end slidably engaged with the engagement portion 23bb of the joint portion 23b in the thermal expansion direction F1.
In the external water supply pipe 23, the joint portion 23c includes therein: the flow passage 23ca and the engagement portion 23cb communicating with the flow passage 23 ca. The outflow end 23ab of the tube main body 23a is fitted into the engagement portion 23cb of the joint portion 23 c. Thereby, the outflow end portion 23ab is engaged with the engagement portion 23cb, and the tube main body 23a communicates with the flow passage 23ca in the joint portion 23 c. Further, an O-ring 27b is interposed between the outflow end 23ab and the engagement portion 23 cb. The O-ring 27b is an example of a sliding member that enables the end portion (the outflow end portion 23ab in fig. 4) of the tube main body 23a to slide in the thermal expansion direction F1 with respect to the joint portion 23 c. The tube main body 23a is connected to the joint portion 23c such that the outflow end portion 23ab is slidable in the thermal expansion direction F1 with respect to the engagement portion 23cb via the O-ring 27 b. That is, the outflow end portion 23ab of the tube main body 23a is a free end slidably engaged with the engagement portion 23cb of the joint portion 23c in the thermal expansion direction F1.
The O- rings 27a and 27b are provided on the inner wall portions of the engagement portions 23bb and 23cb of the joint portions 23b and 23c, respectively, but are not limited thereto, and may be provided on the outer wall portions of the inflow end portion 23aa and the outflow end portion 23ab of the tube main body 23a, respectively.
In embodiment 1, the stress absorbing structure of the external water supply pipe 23 is configured by the joining portions 23b, 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 O- rings 27a, 27b, and the joining portions 23b, 23c that enable the inflow end portion 23aa and the outflow end portion 23ab of the pipe main body 23a to slide relative to the joining portions 23b, 23c in the thermal expansion direction F1. In this stress absorbing structure, for example, as shown in fig. 4, the joining portions 23b, 23c fixed to the outer wall portion of the exhaust valve housing 10 change from a state a1 before thermal expansion to a state a2 after thermal expansion in accordance with the thermal expansion of the exhaust valve housing 10.
Specifically, as shown in fig. 4, the joint portion 23b is displaced downward in the thermal expansion direction F1 together with the outer wall portion of the exhaust valve box 10 after thermal expansion. At this time, the inflow end portion 23aa of the pipe main body 23a is relatively slid with respect to the engagement portion 23bb via the O-ring 27a while maintaining the state of being engaged with the engagement portion 23bb of the joint portion 23 b. This suppresses the occurrence of stress between the joint portion 23b and the inflow end portion 23aa of the tube main body 23 a. In parallel with this, the joint portion 23c is displaced toward the upper side in the thermal expansion direction F1 together with the outer wall portion of the exhaust valve box 10 after thermal expansion. At this time, the outflow end portion 23ab of the tube main body 23a is slid relative to the engagement portion 23cb via the O-ring 27b while maintaining the state of being engaged with the engagement portion 23cb of the engagement portion 23 c. Thereby, the occurrence of stress between the joint portion 23c and the outflow end portion 23ab of the tube main body 23a is suppressed. Due to the sliding action of the pipe main body 23a and the joint portions 23b and 23c of the O- rings 27a and 27b, the stress of the external water supply pipe 23 accompanying the thermal expansion of the exhaust valve box 10 is absorbed.
Then, the joints 23b and 23c change from the post-thermal-extension state a2 to the pre-thermal-extension state a1 in accordance with thermal contraction of the exhaust valve box 10. In this case, the joining portions 23b and 23c are displaced in the opposite direction to the above-described thermal expansion. With this displacement, the inflow end portion 23aa and the outflow end portion 23ab of the tube main body 23a slide relative to the engagement portions 23bb, 23cb of the joint portions 23b, 23c via the O- rings 27a, 27b, respectively.
Although not particularly shown, in embodiment 1, the stress absorbing structure of the external water supply pipe 22 is such that the inflow end portion of the pipe main body 22a is a free end slidably engaged with the joint portion 22b in the thermal expansion direction F1, and the outflow end portion of the pipe main body 22a is a fixed end fixed to the outer wall portion of the exhaust valve box 10 by the joint portion 22 c. In this stress absorbing structure, the joint portion 22b has the same structure as the joint portion 23b of the stress absorbing structure of the external water supply pipe 23 described above. Further, an O-ring (not shown) is provided between the joint portion 22b and the inflow end portion of the tube main body 22a, and the O-ring enables the inflow end portion of the tube main body 22a to slide in the thermal expansion direction F1 with respect to the joint portion 22 b.
In such a stress absorbing structure, the occurrence of stress between the joint portion 22b and the inflow end portion of the tube main body 22a and the occurrence of stress between the joint portion 22c and the outflow end portion of the tube main body 22a are suppressed by the sliding action of the tube main body 22a and the joint portion 22b by the O-ring. As a result, the stress of the external water supply pipe 22 following the thermal expansion of the exhaust valve box 10 is absorbed. Then, as in the case of 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 in accordance with thermal contraction of the exhaust valve box 10.
(modification of stress absorbing Structure)
Next, a modified example of the stress absorbing structure of the external water supply pipe of the present invention will be described. Fig. 5 is a schematic view showing a modification of the stress absorbing structure of the external water supply pipe in embodiment 1 of the present invention. Fig. 5 illustrates a stress absorbing structure of the external water supply pipe 33 as a modification of the stress absorbing structure. In this modification, the external water supply pipe 33 is joined to the outer wall portion of the exhaust valve box 10 instead of the external water supply pipe 23 shown in fig. 2 and the like. In the external water supply pipe 33 shown in fig. 5, the same components as those of the external water supply pipe 23 are denoted by the same reference numerals.
As shown in fig. 5, the pipe main body 33a of the external water supply pipe 33 is a variable-structure pipe that can expand and contract in the thermal expansion direction F1 of the external water supply pipe 33. As a variable structure of the tube main body 33a, for example, a bent tube structure having a tube length longer than a separation distance between the tube and the joint portions 23b and 23c, such as a U-shaped tube structure or an S-shaped tube structure shown in fig. 5, can be exemplified. The joint portion 23b has the above-described flow passage 23ba therein. The inflow end portion 33aa of the tube main body 33a is fixed to the joint portion 23b by fastening or the like so as to communicate the tube main body 33a with the flow passage 23 ba. The joint portion 23c has the above-described flow passage 23ca therein. The outflow end portion 33ab of the tube main body 33a is fixed to the joint portion 23c by fastening or the like so as to communicate the tube main body 33a with the flow passage 23 ca. That is, in this modification, the inflow end portion 33aa and the outflow end portion 33ab of the tube main body 33a are fixed ends fixed to the joint portions 23b and 23c, respectively.
The stress absorbing structure of the external water supply pipe 33 of this modification is constituted by a pipe main body 33a of a variable structure that can expand and contract in the thermal expansion direction F1 of the external water supply pipe 33. In this stress absorbing structure, as shown in fig. 5, for example, the joining portions 23b, 23c fixed to the outer wall portion of the exhaust valve housing 10 are displaced in a direction (thermal expansion direction F1) in which they are separated from each other in accordance with thermal expansion of the exhaust valve housing 10.
Specifically, as shown in fig. 5, the joint portion 23b is displaced downward in the thermal expansion direction F1 together with the outer wall portion of the exhaust valve box 10 after thermal expansion. In parallel with this, the joint portion 23c is displaced toward the upper side in the thermal expansion direction F1 together with the outer wall portion of the exhaust valve box 10 after thermal expansion. At this time, the tube main body 33a deforms so as to open the tube portion of the variable structure (U-shaped tube portion in fig. 5) in accordance with the displacement amount (increase amount of separation distance) of the joint portions 23b, 23c, and extends in the thermal extension direction F1. This suppresses the occurrence of stress between the joints 23b and 23c and the respective end portions of the pipe main body 33a, and therefore, the stress of the external water supply pipe 33 following the thermal expansion of the exhaust valve box 10 is absorbed.
Then, the joints 23b and 23c change from the state after thermal expansion to the state before thermal expansion in accordance with thermal contraction of the exhaust valve housing 10. In this case, the joining portions 23b and 23c are displaced in the opposite direction to the above-described thermal expansion. With this displacement, the tube main body 33a deforms so as to close the tube portion of the variable structure in accordance with the amount of displacement (the amount of reduction in the separation distance) of the joint portions 23b, 23c, thereby contracting in the thermal extension direction F1.
Although not particularly shown, the stress absorbing structure of this modification can also be applied to the external water supply pipe 22. For example, the stress absorbing structure of the external water supply pipe 22 is constituted by a pipe main body 22a having a variable structure that can expand and contract in the thermal expansion direction F1 of the external water supply pipe 22. The inflow end and the outflow end of the tube main body 22a are fixed to the joint portions 22b, 22c, respectively. The stress absorbing structure of the external water supply pipe 22 operates in the same manner as the stress absorbing structure of the external water supply pipe 33 shown in fig. 5.
As described above, in the cooling structure according to embodiment 1 of the present invention, the cooling chamber 21 is formed in the upper portion of the exhaust valve box 10 with respect to the exhaust port 10a so as to surround the outer periphery of the valve rod guide 11 that guides the sliding movement of the valve rod 6b of the exhaust valve 6, and the external water supply pipes 22 and 23 for supplying the cooling water for cooling the valve rod guide 11 to the cooling chamber 21 are disposed so as to communicate with the cooling chamber 21 from the lower side of the exhaust valve box 10 through the outer side and on the upper side with respect to the exhaust port 10 a.
Therefore, the cooling water can be supplied to the cooling chamber 21 in the exhaust valve housing 10 by bypassing the side wall facing the exhaust port 10a of the exhaust valve housing 10. This can 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, the occurrence of sulfuric acid corrosion in the exhaust valve housing 10 can be suppressed, and the valve rod guide 11 provided in the exhaust valve housing 10 can be cooled by the cooling water in the cooling chamber 21. Further, by cooling the valve rod guide portion 11, an excessive decrease in the viscosity of the lubricating oil between the valve rod guide portion 11 and the valve rod 6b can be suppressed. As a result, a film of lubricating oil can be appropriately formed between the valve rod guide 11 and the valve rod 6b, and therefore, smooth sliding of the valve rod 6b in the valve rod guide 11 can be maintained.
Here, as an example of the marine diesel engine 1, a cam type engine in which engine operation such as fuel injection to a combustion chamber is controlled by rotation of a cam is exemplified, but in recent years, an electronically controlled engine in which engine operation is electronically controlled has been developed. In general, a cam type engine is adjusted to optimize engine operation for a predetermined engine load. In contrast, the electronically controlled engine can be adjusted to optimize the engine operation not only when the engine load is 0% or 100%, but also when the engine load is in a range of more than 0% and less than 100% (so-called partial load). Therefore, the electronically controlled engine can improve fuel economy over a wide range of engine loads as compared to a cam-type engine. On the other hand, the temperature of the exhaust gas decreases as the fuel economy improves. That is, compared to the cam-type engine, the problem of "sulfuric acid corrosion in the exhaust valve box due to the generated sulfuric acid caused by an excessive temperature decrease of the exhaust gas in the exhaust port" tends to occur significantly in the electronically controlled engine. According to the cooling structure of embodiment 1 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, and therefore, it is possible to solve the above-described problem also for an electronically controlled engine, not only for a cam-type engine.
In the cooling structure according to embodiment 1 of the present invention, since the external water supply pipes 22 and 23 are disposed so as to pass through the outside of the exhaust valve box 10, the cooling water can be supplied to the cooling chamber 21 in the exhaust valve box 10 without passing through the side wall of the exhaust valve box 10 (the side wall facing the exhaust port 10 a) that has been heated by the heat of the exhaust gas in the exhaust port 10 a. This can avoid a situation in which the cooling water is unintentionally heated by the heat of the exhaust gas while being supplied to the cooling chamber 21, and as a result, the cooling water at a temperature sufficient to cool the valve rod guide portion 11 can be effectively supplied to the cooling chamber 21, and therefore, the cooling effect of the cooling water on the valve rod guide portion 11 can be improved.
In the cooling structure according to embodiment 1 of the present invention, stress absorbing structures for absorbing stress generated in the pipes due to thermal expansion of the exhaust valve box 10 are provided in the external water supply pipes 22 and 23, respectively. Therefore, even when the exhaust valve housing 10 thermally expands due to the heat of the exhaust gas in the exhaust port 10a or the like, the stress generated in the external water supply pipes 22 and 23 due to the thermal expansion can be absorbed, and as a result, the external water supply pipes 22 and 23 can be prevented from being damaged due to the stress due to the thermal expansion.
In the cooling structure according to embodiment 1 of the present invention, an internal flow passage that connects the cooling chamber 21 and the external water supply pipe 22 is formed in the upper portion of the exhaust valve box 10 with respect to the exhaust port 10a so as to merge with the cooling chamber 21 in the circumferential direction of the cooling chamber 21. Therefore, the cooling water supplied from the external water supply pipe 22 to the cooling chamber 21 through the internal flow path can be made to flow in the circumferential direction of the cooling chamber 21. This can suppress stagnation of the cooling water in the cooling chamber 21, and the cooling water can be circulated throughout the entire area in the cooling chamber 21. As a result, the cooling effect of the cooling water in the cooling chamber 21 on the valve rod guide portion 11 can be promoted to be improved.
In the cooling structure according to embodiment 1 of the present invention, the internal flow path that connects the cooling chamber 21 and the external water supply pipe 23 is formed in the upper portion of the exhaust valve box 10 with respect to the exhaust port 10a so as to merge with the cooling chamber 21 on the side opposite to the cooling water outlet 26 across the cooling chamber 21. Therefore, the flow path of the cooling water in the cooling chamber 21 from the junction of the internal flow path and the cooling chamber 21 to the cooling water outlet 26 can be made longer than the flow path formed on the same side as the cooling water outlet 26. This enables the cooling water supplied from the external water supply pipe 23 to the cooling chamber 21 through the internal flow path to flow a long distance in the cooling chamber 21 until the cooling water is discharged from the cooling water outlet 26. As a result, the cooling effect of the cooling water in the cooling chamber 21 on the valve rod guide portion 11 can be promoted to be improved.
(embodiment mode 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 an example of a cooling structure according to embodiment 2 of the present invention. The marine diesel engine according to embodiment 2 includes an exhaust valve housing 10A shown in fig. 6 instead of the exhaust valve housing 10 according to embodiment 1. The exhaust valve box 10A includes external water supply pipes 42 and 43 instead of the external water supply pipes 22 and 23 in embodiment 1 described above. As shown in fig. 6, the lower flow passages 24a and 24b are not formed in the outer wall portion of the exhaust valve housing 10A, and the cooling water passages 3a and 3b are formed in the upper side in the cylinder cover 3. A circumferential groove 7c is formed between the cooling water passages 3a and 3b and the cooling water passage 7b of the exhaust valve seat 7. The cooling structure of embodiment 2 is a cooling structure for the exhaust valve box 10A as described above. Other structures are the same as those of embodiment 1, and the same components are denoted by the same reference numerals.
In embodiment 2, for example, as shown in fig. 6, the cooling structure of the exhaust valve housing 10A includes: the cooling water passages 3a and 3b in the cylinder cover 3, the external water supply pipes 42 and 43, the cooling chamber 21, and the internal passages 25a, 25b, and 25 c.
As shown in fig. 6, the external water supply pipe 42 includes a joint portion 42b instead of the joint portion 22b in embodiment 1. An inflow end portion of the pipe main body 22a of the external water supply pipe 42 is joined to an upper portion of the cylinder cover 3 through a joint portion 42b to communicate with the cooling water passage 3a inside the cylinder cover 3. The external water supply pipe 42 has the same configuration as 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.
As shown in fig. 6, the joint portion 42b has a flow passage 42ba therein. The joining portion 42b joins the inflow end portion of the pipe main 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 main body 22a via the flow passage 42 ba.
As shown in fig. 6, the external water supply pipe 43 includes a joint portion 43b instead of the joint portion 23b in embodiment 1. An inflow end portion of the pipe main body 23a of the external water supply pipe 43 is joined to an upper portion of the cylinder cover 3 through a joint portion 43b to communicate with the cooling water passage 3b inside the cylinder cover 3. The external water supply pipe 43 has the same configuration as 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 joining portion 43b as described above.
As shown in fig. 6, the joint portion 43b has a flow passage 43ba therein. The joining portion 43b joins the inflow end portion 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 43 ba.
As described above, the cylinder cover 3 to which the inflow end portions of the external water supply pipes 42 and 43 are joined by the joining portions 42b and 43b is a member constituting one cylinder in the marine diesel engine, and is a portion located below the exhaust valve box 10A as shown in fig. 6. In embodiment 2, as shown in fig. 6, the cylinder cover 3 includes cooling water passages 3a and 3b inside. Further, as shown in fig. 6, a circumferential groove 7c is formed between each of the cooling water passages 3a and 3b of the cylinder cover 3 and the cooling water passage 7b of the exhaust valve seat 7. The circumferential groove 7c is an annular groove similar to that in embodiment 1 described above, and is formed in at least one of the cylinder head 3 and the exhaust valve seat 7. In embodiment 2, the exhaust valve seat 7 is 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. The cooling water passages 3a and 3b are formed in an upper portion of the cylinder cover 3 such that one end portions thereof are open at an upper end surface of the cylinder cover 3 and the other end portions thereof communicate with the cooling water passage 7b in the exhaust valve seat 7 via a circumferential groove 7 c. One of the cooling water paths 3a and 3b communicates the cooling water path 7b in the exhaust valve seat 7 with the flow passage 42ba in the joint portion 42b via the circumferential groove 7c, and the other cooling water path 3b communicates the cooling water path 7b in the exhaust valve seat 7 with the flow passage 43ba in the joint portion 43b via the circumferential groove 7 c.
In the cooling structure of embodiment 2, the cooling water flows into the cooling water passage 7b in the exhaust valve seat 7 from, for example, a lower passage (not shown) in the cylinder cover 3. The cooling water in the cooling water passage 7b flows into the cooling water passage 3a in the cylinder cover 3 through the circumferential groove 7c, and flows from the cooling water passage 3a into the pipe main body 22a through the flow passage 42ba in the joint portion 42b of the external water supply pipe 42. Thereafter, the cooling water flows in the same manner as in embodiment 1 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 through the circumferential groove 7c, and flows from the cooling water passage 3b into the pipe main body 23a through the flow passage 43ba in the joint portion 43b of the external water supply pipe 43. Thereafter, the cooling water flows in the same manner as in embodiment 1 described above.
In embodiment 2, the external water supply pipes 42 and 43 each have a stress absorbing structure that absorbs stress generated in the external water supply pipes 42 and 43 in accordance with thermal expansion of the exhaust valve box 10A. Although not particularly shown, the stress absorbing structures of the external water supply pipes 42 and 43 are the same as those of embodiment 1 described above, except that the inflow end portions of the pipe main bodies 22a and 23a are joined to the upper portion of the cylinder cover 3 by joining portions 42b and 43 b. For example, in the stress absorbing structure of the external water supply pipe 42, an O-ring (not shown) that allows the inflow end portion of the pipe main body 22a to slide in the thermal expansion direction F1 (see fig. 4) with respect to the joint portion 42b is provided between the joint portion 42b and the inflow end portion of the pipe main body 22 a. In the stress absorbing structure of the external water supply pipe 43, an O-ring (not shown) that allows the inflow end portion of the pipe main body 23a to slide in the thermal expansion direction F1 with respect to the joint portion 43b is provided between the joint portion 43b and the inflow end portion of the pipe main body 23 a. Alternatively, the stress absorbing structure of the external water supply pipe 42 may be constituted by a pipe main body 22a having a variable structure that can expand and contract in the thermal expansion direction F1 of the external water supply pipe 42, as in the stress absorbing structure of the above-described modified example (see fig. 5). Similarly, the stress absorbing structure of the external water supply pipe 43 may be constituted by the pipe main body 23a having a variable structure that can expand and contract in the thermal expansion direction F1 of the external water supply pipe 43.
As described above, in the cooling structure according to embodiment 2 of the present invention, the inflow end portion of the external water supply pipe 42 is joined to the upper portion of the cylinder cover 3 by the joint portion 42b so as to communicate the cooling water passage 3a in the cylinder cover 3 with the pipe main body 22a, and the inflow end portion of the external water supply pipe 43 is joined to the upper portion of the cylinder cover 3 by the joint portion 43b so as to communicate the cooling water passage 3b in the cylinder cover 3 with the pipe main body 23a, and the other configuration is the same as that of embodiment 1 described above. Therefore, even in the case of the system in which the inflow end portions of the external water supply pipes 42 and 43 are joined to the upper portion of the cylinder cover 3, a cooling structure having the same operational effects as those of embodiment 1 can be realized.
(embodiment mode 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 an example of a cooling structure according to embodiment 3 of the present invention. The marine diesel engine according to embodiment 3 includes an exhaust valve housing 10B shown in fig. 7 instead of the exhaust valve housing 10A according to 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 embodiment 2. The cooling structure of embodiment 3 is a cooling structure for the exhaust valve box 10B as described above. The other structures are the same as those of embodiment 2, and the same components are denoted by the same reference numerals.
In embodiment 3, for example, as shown in fig. 7, the cooling structure of the exhaust valve box 10B includes: external water supply pipes 52 and 53, cooling water passages 3a and 3b in the cylinder cover 3, the cooling chamber 21, and internal passages 25a, 25b, and 25 c.
As shown in fig. 7, the external water supply pipe 52 does not include the above-described joint portion 42b, and an inflow end portion 52aa of the external water supply pipe 52 is fitted into or screwed into the cooling water passage 3a and the like and joined to the upper portion of the cylinder cover 3. Thus, the pipe main body 22a of the external water supply pipe 52 is disposed so as to communicate with the cooling water passage 3a in the cylinder cover 3. The external water supply pipe 52 has the same configuration as 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 does not include the above-described joint portion 43b, and an inflow end portion 53aa of the external water supply pipe 53 is fitted into or screwed into the cooling water passage 3b and joined to the upper portion of the cylinder cover 3. Thus, the pipe main body 23a of the external water supply pipe 53 is disposed so as to communicate with the cooling water passage 3b in the cylinder cover 3. The external water supply pipe 53 has the same configuration as the external water supply pipe 43 in embodiment 2, except that the inflow end portion 53aa is joined to the upper portion of the cylinder cover 3 as described above.
In the cooling structure of embodiment 3, the cooling water flows into the cooling water passage 7b in the exhaust valve seat 7 from, for example, a lower passage (not shown) in the cylinder cover 3. The cooling water in the cooling water passage 7b flows into the cooling water passage 3a in the cylinder cover 3 through the circumferential groove 7c, and flows into the tube main body 22a of the external water supply tube 52 through the cooling water passage 3 a. Thereafter, the flow of the cooling water is the same as in embodiment 2 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 through the circumferential groove 7c, and flows into the pipe main body 23a of the external water supply pipe 53 through the cooling water passage 3 b. Thereafter, the flow of the cooling water is the same as in embodiment 2 described above.
In embodiment 3, the external water supply pipes 52 and 53 each have a stress absorbing structure that absorbs stress generated in the external water supply pipes 52 and 53 in accordance with thermal expansion of the exhaust valve box 10B. Although not particularly shown, the stress absorbing structures of the external water supply pipes 52 and 53 are the same as those of embodiment 2 described above, except that the inflow end portions 52aa and 53aa are joined to the upper portion of the cylinder cover 3 by fitting or screwing into the cooling water passages 3a and 3 b. For example, in the stress absorbing structure of the external water supply pipe 52, an O-ring (not shown) is provided between the cooling water passage 3a and the inflow end portion 52aa, and the inflow end portion 52aa is slidable in the thermal expansion direction F1 (see fig. 4) with respect to the cooling water passage 3 a. 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 portion 53aa, and the inflow end portion 53aa is slidable in the thermal expansion direction F1 with respect to the cooling water passage 3 b. Alternatively, the stress absorbing structure of the external water supply pipe 52 may be configured by the pipe main body 22a having a variable structure that allows the external water supply pipe 52 to expand and contract in the thermal expansion direction F1, as in the stress absorbing structure of the above-described modified example (see fig. 5). Similarly, the stress absorbing structure of the external water supply pipe 53 may be constituted by the pipe main 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 embodiment 3 of the present invention, the inflow end portion 52aa of the external water supply pipe 52 is joined by fitting or screwing or the like into the cooling water passage 3a to communicate the cooling water passage 3a in the cylinder cover 3 with the pipe main body 22a, and the inflow end portion 53aa of the external water supply pipe 53 is joined by fitting or screwing or the like into the cooling water passage 3b to communicate the cooling water passage 3b in the cylinder cover 3 with the pipe main body 23a, and the other configuration is the same as that of embodiment 2 described above. Therefore, even in the case of the system in which the inflow end portions 52aa and 53aa of the external water supply pipes 52 and 53 are directly joined to the upper portion of the cylinder cover 3, a cooling structure having the same operational effects as those of the above-described embodiment 2 can be realized.
(embodiment mode 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 an example of a cooling structure according to embodiment 4 of the present invention. The marine diesel engine according to embodiment 4 includes an exhaust valve housing 10C shown in fig. 8 instead of the exhaust valve housing 10A according to embodiment 2 described above. As shown in fig. 8, the exhaust valve housing 10C includes a circumferential groove 7C at a lower end of an outer wall portion thereof. The cooling water passages 3a and 3b of the cylinder cover 3 and the cooling water passage 7b of the exhaust valve seat 7 are formed so as to communicate with each other via a circumferential groove 7C of the exhaust valve housing 10C. The cooling structure of embodiment 4 is a cooling structure for the exhaust valve box 10C as described above. Other structures are the same as those in embodiment 2, and the same components are denoted by the same reference numerals.
In embodiment 4, for example, as shown in fig. 8, a cooling structure for an exhaust valve box 10C includes: the circumferential groove 7c, the cooling water passages 3a and 3b in the cylinder cover 3, the external water supply pipes 42 and 43, the cooling chamber 21, and the internal passages 25a, 25b, and 25 c.
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 housing 10C. Specifically, the circumferential groove 7C is formed in a rectangular ring shape along each boundary portion between the cylinder cover 3 and the exhaust valve seat 7 and the exhaust valve housing 10C so as to surround the exhaust port 7 a. The circumferential groove 7c communicates 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.
In the cooling structure according to embodiment 4, the cooling water flows into the cooling water passage 7b in the exhaust valve seat 7 from, for example, a lower passage (not shown) in the cylinder cover 3. The cooling water in the cooling water passage 7b flows into the cooling water passage 3a in the cylinder cover 3 through the circumferential groove 7C of the exhaust valve housing 10C, and flows from the cooling water passage 3a into the pipe main body 22a through the flow passage 42ba in the joint portion 42b of the external water supply pipe 42. Thereafter, the flow of the cooling water is the same as in embodiment 2 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 through the circumferential groove 7C of the exhaust valve box 10C, and flows from the cooling water passage 3b into the pipe main body 23a through the flow passage 43ba in the joint portion 43b of the external water supply pipe 43. Thereafter, the flow of the cooling water is the same as in embodiment 2 described above.
As described above, in the cooling structure according to embodiment 4 of the present invention, the circumferential groove 7C is formed at the lower end corner of the outer wall portion of the exhaust valve housing 10C, and the cooling water passages 3a and 3b in the cylinder cover 3 and the cooling water passage 7b in the exhaust valve seat 7 are respectively communicated via the circumferential groove 7C, and the other configuration is the same as that of embodiment 2 described above. Therefore, even in the case where the circumferential grooves 7C that communicate the cooling water passages 3a and 3b in the cylinder cover 3 with the cooling water passage 7b in the exhaust valve seat 7 are formed at the lower end corner of the outer wall portion of the exhaust valve housing 10C, a cooling structure having the same operational effects as those of embodiment 2 described above can be realized.
In embodiments 1 to 4 described above, the internal flow path that connects the cooling chamber 21 to the external water supply pipe on the upper side of the exhaust port 10A in the exhaust valve boxes 10, 10A, 10B, and 10C is an internal flow path that merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21, or an internal flow path that merges with the cooling chamber 21 on the opposite side of the cooling water outlet 26 from the cooling chamber 21. For example, the internal flow path that connects the cooling chamber 21 to the external water supply pipe on the upper side of the exhaust port 10A in the exhaust valve boxes 10, 10A, 10B, and 10C may be an internal flow path that merges with the cooling chamber 21 along the circumferential direction of the cooling chamber 21 on the opposite side of the cooling water outlet 26 across the cooling chamber 21.
In embodiments 1 to 4, the stress absorbing structure in which the inflow end and the outflow end of the tube main body 23a of the external water supply tubes 23, 43, 53 are respectively made free with respect to the joint portions 23b, 23c, 43b or the cooling water passage 3b in the cylinder cover 3 has been illustrated, but the present invention is not limited to this. For example, the stress absorbing structure of the external water supply pipe 23 may be such that the inflow end portion 23aa of the pipe main body 23a is a free end with respect to the joint portion 23b and the outflow end portion 23ab of the pipe main body 23a is a fixed end with respect to the joint portion 23c, and the inflow end portion 23aa of the pipe main body 23a is a fixed end with respect to the joint portion 23b and the outflow end portion 23ab of the pipe main body 23a is a free end with respect to the joint portion 23 c. This is also the same for the external water supply pipes 43, 53. The stress absorbing structure of the external water supply pipe 22 may be such that the inflow end portion of the pipe main body 22a is fixed to the joint portion 22b and the outflow end portion of the pipe main body 22a is free from the joint portion 22c, or the inflow end portion and the outflow end portion of the pipe main body 22a may be free from the joint portions 23b and 23c, respectively. This is also the same for the external water supply pipes 42, 52.
In embodiments 1 to 4, the opening end (cooling water outlet 26) of the internal flow path 25b is illustrated as the outlet of the cooling water in the cooling chamber 21, but the present invention is not limited to this. For example, the outlet of the cooling water in the cooling chamber 21 may be formed in a region other than the cooling water outlet 26.
In embodiments 1 to 4, the case where two external water supply pipes are joined to an outer wall portion of the exhaust valve housing is exemplified, but the present invention is not limited to this. The number of pipes of the external water supply pipe joined to the outer wall portion of the exhaust valve box or the like may be one or a plurality (two or more).
In the above-described modification, the bent pipe body is exemplified as the pipe body having the variable structure that can expand and contract in the thermal expansion direction of the external water supply pipe, but the present invention is not limited thereto. For example, the variable structure pipe body may be a corrugated structure pipe body that is expandable and contractible in a thermal expansion direction of the external water supply pipe, or a structure in which a plurality of cylindrical bodies are slidably fitted.
The above embodiments 1 to 4 and the modified examples are not limited to the present invention, and the present invention includes a configuration in which the above-described respective components are appropriately combined. Further, other embodiments, examples, operation techniques, and the like, which are 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.
Industrial applicability of the invention
As described above, the cooling structure according to the present invention is useful for an exhaust valve box of a marine diesel engine, and is particularly suitable for a cooling structure capable of suppressing the occurrence of sulfuric acid corrosion in the exhaust valve box and cooling a valve rod guide portion provided in the exhaust valve box.
Description of the symbols
1 Diesel engine for ship
2 cylinder sleeve
3 jar cover
3a, 3b cooling water path
4 piston
5 piston rod
6 exhaust valve
6a valve core
6b valve rod
7 exhaust valve seat
7a exhaust port
7b Cooling Water 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 working device
14 connecting piping
15 exhaust manifold
21 cooling chamber
22. 23, 33, 42, 43, 52, 53 external water supply pipe
22a, 23a, 33a tube body
22b, 22c, 23b, 23c, 42b, 43b junction
Flow paths of 22ba, 23ca, 42ba and 43ba
23aa, 33aa, 52aa, 53aa inflow end
23ab, 33ab outflow end
23bb, 23cb engagement portion
24a, 24b lower flow path
25a, 25b, 25c internal flow path
26 outlet for cooling water
27a, 27b O Ring
Direction of thermal elongation of F1

Claims (8)

1. A cooling structure for an exhaust valve box having therein: an exhaust gas path for discharging exhaust gas from a combustion chamber of a marine diesel engine; and a valve rod guide portion for guiding sliding of a valve rod of an exhaust valve for opening and closing between the combustion chamber and the exhaust gas path, the cooling structure being characterized by comprising:
a cooling chamber formed in an upper portion of the exhaust valve housing with respect to the exhaust gas passage so as to surround an outer periphery of the valve rod guide, the cooling chamber being configured to cool the valve rod guide with cooling water; and
and an external water supply pipe which is disposed so as to communicate with the cooling chamber from a lower side of the exhaust valve box through an outer side thereof and at an upper side thereof with respect to the exhaust gas passage, and which supplies the cooling water to the cooling chamber.
2. The cooling structure according to claim 1,
the external water supply pipe includes a stress absorbing structure that absorbs stress generated in the external water supply pipe in accordance with thermal expansion of the exhaust valve box.
3. The cooling structure according to claim 2,
the stress absorbing structure is constituted by a joint portion and a slide member,
the joint part joins an end of the pipe main body of the external water supply pipe to an outer wall part of the exhaust valve box,
the sliding member enables the end portion of the tube main body to slide in the thermal expansion direction with respect to the joint portion.
4. The cooling structure according to claim 2,
the stress absorbing structure is constituted by a joint portion and a slide member,
the joint part joints the end part of the pipe main body of the external water supply pipe to the upper part of the cylinder cover positioned at the lower side of the exhaust valve box,
the sliding member enables the end portion of the tube main body to slide in the thermal expansion direction with respect to the joint portion.
5. The cooling structure according to claim 2,
the stress absorbing structure is constituted by a variable-structure pipe body that is expandable and contractible in a thermal expansion direction of the external water supply pipe.
6. The cooling structure according to any one of claims 1 to 5,
an internal flow path formed in an upper portion of the exhaust valve box with respect to the exhaust gas path and merging with the cooling chamber along a circumferential direction of the cooling chamber,
the external water supply pipe communicates with the cooling chamber through the internal flow path.
7. The cooling structure according to any one of claims 1 to 5,
an internal flow path formed in an upper portion of the exhaust valve box with respect to the exhaust gas path and merging with the cooling chamber on a side opposite to the cooling chamber with the cooling water outlet interposed therebetween,
the external water supply pipe communicates with the cooling chamber through the internal flow path.
8. The cooling structure according to any one of claims 1 to 7,
the external water supply pipe is provided in plurality.
CN201980075774.1A 2018-11-19 2019-09-24 Cooling structure Pending CN113167192A (en)

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JP2018-216818 2018-11-19
JP2018216818A JP7241512B2 (en) 2018-11-19 2018-11-19 cooling structure
PCT/JP2019/037197 WO2020105273A1 (en) 2018-11-19 2019-09-24 Cooling structure

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CN113167192A true CN113167192A (en) 2021-07-23

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WO (1) WO2020105273A1 (en)

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JPS59121410U (en) * 1983-02-07 1984-08-16 三菱重工業株式会社 Cooling system for supply and exhaust valves
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