CA2471993C - Rust prevention system of an outboard motor - Google Patents
Rust prevention system of an outboard motor Download PDFInfo
- Publication number
- CA2471993C CA2471993C CA 2471993 CA2471993A CA2471993C CA 2471993 C CA2471993 C CA 2471993C CA 2471993 CA2471993 CA 2471993 CA 2471993 A CA2471993 A CA 2471993A CA 2471993 C CA2471993 C CA 2471993C
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- CA
- Canada
- Prior art keywords
- cylinder head
- water jacket
- exhaust device
- gasket
- outboard motor
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- 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.)
- Expired - Fee Related
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- Exhaust Silencers (AREA)
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
- Prevention Of Electric Corrosion (AREA)
Abstract
There is provided a rust prevention system of an outboard motor, comprising: a cylinder head (14) having a water jacket (14a); an exhaust device (35) having a water jacket (36) and fastened to the cylinder head; and a gasket (43) disposed between the cylinder head and the exhaust device, wherein a sacrificial anode (37) is disposed in one of the water jacket of the cylinder head and the water jacket of the exhaust device, and the cylinder head and the exhaust device are electrically connected to each other by electroconductive means (43a).
Description
SPECIFICATION
TITLE OF THE INVENTION
RUST PREVENTION SYSTEM OF AN OUTBOARD
MOTOR TECHNICAL FIELD
The present invention relates to a rust prevention system of an outboard motor.
BACKGROUND OF THE INVENTION
Conventionally, a water-cooled engine utilizing sea water as cooling water is used in outboard motors, and this results in the cooling water containing salt, which tends to cause rust to develop in various parts in the engine due to an electric potential difference. For this reason, in a case where the cylinder block and/or cylinder head are made of an aluminum alloy, for example, a metal that tends to be at a lower electric potential such as zinc (Zn) is used as a sacrificial anode which is placed at an appropriate position in the water jacket. (see, for example, Japanese Patent Application No. 2000-314315 published November 14, 2000 (page 4, Figure 3)).
In the above outboard motor, a cylinder block is formed with an exhaust passage and a water jacket, and an outwardly facing opening of the water jacket is closed by an exhaust cover, to which a sacrificial anode is provided so as to be placed inside the water jacket. On the other hand, there are engines in which an exhaust device constituting an exhaust pipe is fastened to the cylinder head.
Because a gasket is provided between the cylinder head and the exhaust device, the cylinder head and the exhaust device are electrically separated from each other. Thus, a sacrificial anode provided to one of the water jacket in the cylinder head or the water jacket in the exhaust device could not prevent rust development in the other. In such an engine, it may be conceived to provide a sacrificial anode to each of the water jackets, but that would complicate the structure.
TITLE OF THE INVENTION
RUST PREVENTION SYSTEM OF AN OUTBOARD
MOTOR TECHNICAL FIELD
The present invention relates to a rust prevention system of an outboard motor.
BACKGROUND OF THE INVENTION
Conventionally, a water-cooled engine utilizing sea water as cooling water is used in outboard motors, and this results in the cooling water containing salt, which tends to cause rust to develop in various parts in the engine due to an electric potential difference. For this reason, in a case where the cylinder block and/or cylinder head are made of an aluminum alloy, for example, a metal that tends to be at a lower electric potential such as zinc (Zn) is used as a sacrificial anode which is placed at an appropriate position in the water jacket. (see, for example, Japanese Patent Application No. 2000-314315 published November 14, 2000 (page 4, Figure 3)).
In the above outboard motor, a cylinder block is formed with an exhaust passage and a water jacket, and an outwardly facing opening of the water jacket is closed by an exhaust cover, to which a sacrificial anode is provided so as to be placed inside the water jacket. On the other hand, there are engines in which an exhaust device constituting an exhaust pipe is fastened to the cylinder head.
Because a gasket is provided between the cylinder head and the exhaust device, the cylinder head and the exhaust device are electrically separated from each other. Thus, a sacrificial anode provided to one of the water jacket in the cylinder head or the water jacket in the exhaust device could not prevent rust development in the other. In such an engine, it may be conceived to provide a sacrificial anode to each of the water jackets, but that would complicate the structure.
BRIEF SUMMARY OF THE INVENTION
In view of such problems of the prior art, a primary object of the present invention is to provide a rust prevention system which is simple in structure but can effectively prevent rust development in a water cooled engine having an exhaust device fastened to a cylinder head.
A second object of the present invention is to provide a rust prevention system which is simple in structure and can effectively prevent rust development in an water cooled engine in which the cylinder head and the exhaust device have respective water jackets and a gasket is interposed between the cylinder head and the exhaust device so that the water jackets of the cylinder head and the exhaust device are not connected to each other.
According to the present invention, such objects can be accomplished by providing a rust prevention system of an outboard motor, comprising: a cylinder head having a water jacket ; an exhaust device having a water jacket and fastened to the cylinder head; and a gasket disposed between the cylinder head and the exhaust device, wherein a sacrificial anode is disposed in one of the water jacket of the cylinder head and the water jacket of the exhaust device, and the cylinder head and the exhaust device are electrically connected to each other by electroconductive means. In one preferred embodiment of the present invention, the sacrificial anode may be disposed in the water jacket of the exhaust device.
According to such a structure, even though the cylinder head and the exhaust device each having a water jacket are not connected to each other via the water jackets, the electrical connection of these component parts allows the sacrificial anode provided to one of the cylinder head and the exhaust device to provide rust prevention (or anti-corrosion) effect to both of them. This is particularly effective in an outboard motor where the cylinder head and the exhaust device are separated from each other via a gasket.
In view of such problems of the prior art, a primary object of the present invention is to provide a rust prevention system which is simple in structure but can effectively prevent rust development in a water cooled engine having an exhaust device fastened to a cylinder head.
A second object of the present invention is to provide a rust prevention system which is simple in structure and can effectively prevent rust development in an water cooled engine in which the cylinder head and the exhaust device have respective water jackets and a gasket is interposed between the cylinder head and the exhaust device so that the water jackets of the cylinder head and the exhaust device are not connected to each other.
According to the present invention, such objects can be accomplished by providing a rust prevention system of an outboard motor, comprising: a cylinder head having a water jacket ; an exhaust device having a water jacket and fastened to the cylinder head; and a gasket disposed between the cylinder head and the exhaust device, wherein a sacrificial anode is disposed in one of the water jacket of the cylinder head and the water jacket of the exhaust device, and the cylinder head and the exhaust device are electrically connected to each other by electroconductive means. In one preferred embodiment of the present invention, the sacrificial anode may be disposed in the water jacket of the exhaust device.
According to such a structure, even though the cylinder head and the exhaust device each having a water jacket are not connected to each other via the water jackets, the electrical connection of these component parts allows the sacrificial anode provided to one of the cylinder head and the exhaust device to provide rust prevention (or anti-corrosion) effect to both of them. This is particularly effective in an outboard motor where the cylinder head and the exhaust device are separated from each other via a gasket.
In the case that the gasket is made of an electroconductive material coated with an electrically insulating material, it is possible that the electroconductive means comprises an uncoated portion of the gasket so that the cylinder head and the exhaust device are electrically connected to each other via the uncoated portion of the gasket. This can avoid complicating the structure and thus minimize the cost.
Further, it will be preferred if the uncoated portion is provided around a bolt insertion hole formed in the gasket because this can place the uncoated portion at a part where a largest fastening pressure will be applied, thus achieving a reliable electrical connection.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
Now the present invention is described in the following with reference to the appended drawings, in which:
Figure 1 is a side view showing an essential part of an outboard motor to which the present invention is applied;
Figure 2 is a view seen along the arrow II in Figure 1 and showing a top plan view of the outboard motor to which the present invention is applied;
20 Figure 3 is an enlarged cross-sectional view of an essential part taken along the line III-III in Figure 1;
Figure 4 is an outer view of an exhaust pipe seen along the arrow IV in Figure 2;
Figure 5 is an enlarged cross-sectional view of an essential part of the engine taken along the line V-V in Figure 4; and Figure 6 is a plan view of a gasket seen along the line VI-VI in Figure 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1 and 2 show a portion around an engine of an outboard motor constructed according to the present invention. This outboard motor 1 is a known type adapted to be attached to a stem plate 3 via a stem bracket 2, and its engine 4 is mounted on a mount case 7 that is substantially integral with a swivel case 6 which in turn is connected to the stem bracket 2 so as to be pivotable around a laterally extending tilt shaft 5. A substantially whole part of the engine 4 mounted on the mount case 7 is covered by a detachable engine cover 8.
The mount case 7 is fixed on top of an extension case 9. Inside the mount case 7, a drive shaft 10 extending to a screw (not shown) is connected to a crankshaft 11.
The engine 4 may consist of a vertical crankshaft engine of a 4-cylinder in-line type, for example, which comprises a crankcase 12, cylinder block 13 and cylinder head 14, and is arranged such that the crankcase 12 faces in a forward direction with respect to a watercraft body. The cylinder head 14 is provided with an intake port 15 and an exhaust port 16, and further formed with a combustion chamber 19 which is intermittently brought into flow communication with the intake port 15 and exhaust port 16 via an intake valve 17 and an exhaust valve 18, respectively (Figure 2).
An intake device 20 is disposed at one lateral side of the crankcase 12, cylinder block 13 and cylinder head 14 so as to oppose them. The intake device 20 comprises an intake silencer chamber 21 and a throttle body 22 which are disposed in front of the crankcase 12 with respect to a direction of travel of the watercraft so as to oppose the crankcase 12, and an intake manifold 23 which is connected to an outlet of the throttle body 22 and divided into branches so as to be connected to each of the intake ports 15 of the cylinders. The intake device 20 is fastened to the engine 4 with a portion of the intake manifold 23 closer to the throttle body 22 being bolted to a lateral side of the crankcase 12 while a downstream end of the intake manifold 23 being bolted to a lateral side of the cylinder head 14.
The individual intake pipes forked from the intake manifold 23 and connected to respective intake ports 15 are each attached with a fuel injection valve 24. The fuel injection valve 24 is arranged such that it projects out obliquely toward a lateral side of a head cover 25 attached to the cylinder head 14. As shown in Figure 1, the projecting ends of the fuel injection valves 24 are joined to a fuel rail 26 that extends vertically along the lateral side of the cylinder head 14.
As seen in Figure 3, the engine of the illustrated embodiment consists of a DOHC engine. As shown, an intake valve camshaft 31 serving as a driving cam shaft and a rocker arm 32 that oscillates following a cam 31a of the camshaft 31 are accommodated in the head cover 25. Further, an exhaust valve camshaft 33 and a rocker arm 34 that oscillates following a cam 33a of the camshaft 33 are also provided in the head cover 25. The camshafts 31, 33 and rocker shafts 32a, 34a for supporting the rocker arms 32, 34, respectively, are supported by a cam holder 53 which is secured by a bolt 52 onto a packing surface 51 of the cylinder head 14 on a side opposite to a combustion chamber 19. In this way, it is possible to sub-assemble the supporting structure of the camshafts 31, 33 easily.
In the shown embodiment, the fuel supply to each of the fuel injection valves 24 via the fuel rail 26 is canied out by a fuel supply system comprising a low pressure pump 28 attached to the head cover 25 and a high pressure pump consisting of an electromagnetic pump not shown in the drawing. The low pressure pump 28.may be implemented as a diaphragm-type pump which is attached to a lateral side of the head cover in an inclined attitude such that its push rod 28a extends toward the intake valve camshaft 31 obliquely downward when seen in Figure 3. The end of the push rode 28a slidably contacts the cam 31a so that in response to the cam rotation, the push rod 28a reciprocates back and forth to drive the low pressure pump 28.
An exhaust pipe 35 that serves as an exhaust device is attached to the cylinder head 14 so as to be in flow communication with the exhaust port 16. The exhaust pipe 35 is equipped with a water jacket 36 surrounding an exhaust passage 35a.
Further, a water temperature sensor 39 is attached to the exhaust pipe 35 to detect the water temperature of the water jacket 36 so that the detected temperature can be used in engine control. Within the water jacket 36 is disposed a sacrificial anode 37.
The sacrificial anode 37 is screwed onto a pillar-like portion 35b projecting from an outer wall of the exhaust pipe 35 into the water jacket 36. Further, the outer wall of the exhaust pipe 35 is formed with an opening 35c (Figure 4) at a position aligned with the sacrificial anode 37 in order to allow maintenance of the sacrificial anode 37, and a lad 15 38 is fastened to the opening 35c by a screw 54 to normally close the opening 35c.
Figure 4 shows an outer appearance of the side of the exhaust pipe 35. As shown in the drawing, the exhaust pipe 35 is formed with five bolt insertion holes 41. In this embodiment, the sacrificial anode 37 can be provided at two positions (see the numerals 35b, 35c in Figure 4), and two of the bolt insertion holes 41 are arranged near the two positions.
As shown in Figure 5, bolts 42 inserted into the bolt insertion holes 41 are screwed into threaded holes 14b which are provided at corresponding positions in the cylinder head 14 to fasten the exhaust pipe 35 to the cylinder head 14.
Between the mutually facing surfaces of the cylinder head 14 and the exhaust pipe 35 is interposed a gasket 43. The gasket is typically made of an electroconductive material such as a metal and coated with an electrically insulating material.
As shown in Figure 6, the gasket 43 is formed with holes 44 corresponding to the bolt insertion holes 41. Annular uncoated portions 43a are provided at portions of the gasket 43 surrounding two of the holes 44 located near the sacrificial anodes 37.
Front and rear surfaces of the gasket 43 (i.e., a surface facing the cylinder head 14 and a surface facing the exhaust pipe 35) are each applied with an electrically insulating surface treatment material, and the uncoated portions 43a where the electroconductive gasket material is exposed are formed by removing the coating at the portions surrounding the two holes 44.
In this way, when the exhaust pipe 35 is fastened to the cylinder head 14, they are electrically connected to each other via the uncoated portions 43a of the gasket 43.
Thus, even though the water jacket 36 in the exhaust pipe 35 and the water jacket 14a in the cylinder head 14 are not in flow communication with each other, the provision of the sacrificial anode 37 in the water jacket 36 of the exhaust pipe 35 can prevent rust development in the cylinder head 14.
It should be noted that in the shown embodiment, the sacrificial anodes 37 are disposed in the water jacket 36 of the exhaust pipe 35, but they may be disposed at appropriate position(s) within the water jacket 14a of the cylinder head 14.
In such a case also, the rust prevention effect of the sacrificial anode can be obtained both in the cylinder head 14 and in the exhaust pipe 35 because they are electrically connected to each other.
In the above embodiment, the sacrificial anodes 37 are screwed on the pillar-like portions 35b projecting into the water jacket 36. In this way, a larger surface area of the sacrificial anodes 37 exposed to the water body can be achieved compared with a case where the sacrificial anodes 37 are integrally attached to the lad 38, for example, and therefore, the sacrificial anodes 37 can be made more compact to achieve a given rust prevention effect and this can improve maintenanceability of the sacrificial anodes 37.
As described above, according to the present invention, even when the cylinder head and the exhaust device each having a water jacket are not connected to each other via the water jackets, electrical connection of the two component parts can allow a sacrificial anode provided for one of them to achieve rust prevention (or anti-corrosion) effect in both of them.
Particularly, when a gasket made of an electroconductive material coated with an electrically insulating material is interposed between the cylinder head and the exhaust device, the electrical connection can be achieved by providing an uncoated portion to the gasket such that the cylinder head and the exhaust device are electrically connected to each other via the uncoated portion. This can avoid complicating the structure and thus minimize the cost. Further, it will be preferred if the uncoated portion is provided so as to surround a bolt insertion hole formed in the gasket because this can place the uncoated portion at a part where a largest fastening pressure will be applied, thus achieving a reliable electrical connection.
Although the present invention has been described in terms of a preferred embodiment thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims.
Further, it will be preferred if the uncoated portion is provided around a bolt insertion hole formed in the gasket because this can place the uncoated portion at a part where a largest fastening pressure will be applied, thus achieving a reliable electrical connection.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
Now the present invention is described in the following with reference to the appended drawings, in which:
Figure 1 is a side view showing an essential part of an outboard motor to which the present invention is applied;
Figure 2 is a view seen along the arrow II in Figure 1 and showing a top plan view of the outboard motor to which the present invention is applied;
20 Figure 3 is an enlarged cross-sectional view of an essential part taken along the line III-III in Figure 1;
Figure 4 is an outer view of an exhaust pipe seen along the arrow IV in Figure 2;
Figure 5 is an enlarged cross-sectional view of an essential part of the engine taken along the line V-V in Figure 4; and Figure 6 is a plan view of a gasket seen along the line VI-VI in Figure 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1 and 2 show a portion around an engine of an outboard motor constructed according to the present invention. This outboard motor 1 is a known type adapted to be attached to a stem plate 3 via a stem bracket 2, and its engine 4 is mounted on a mount case 7 that is substantially integral with a swivel case 6 which in turn is connected to the stem bracket 2 so as to be pivotable around a laterally extending tilt shaft 5. A substantially whole part of the engine 4 mounted on the mount case 7 is covered by a detachable engine cover 8.
The mount case 7 is fixed on top of an extension case 9. Inside the mount case 7, a drive shaft 10 extending to a screw (not shown) is connected to a crankshaft 11.
The engine 4 may consist of a vertical crankshaft engine of a 4-cylinder in-line type, for example, which comprises a crankcase 12, cylinder block 13 and cylinder head 14, and is arranged such that the crankcase 12 faces in a forward direction with respect to a watercraft body. The cylinder head 14 is provided with an intake port 15 and an exhaust port 16, and further formed with a combustion chamber 19 which is intermittently brought into flow communication with the intake port 15 and exhaust port 16 via an intake valve 17 and an exhaust valve 18, respectively (Figure 2).
An intake device 20 is disposed at one lateral side of the crankcase 12, cylinder block 13 and cylinder head 14 so as to oppose them. The intake device 20 comprises an intake silencer chamber 21 and a throttle body 22 which are disposed in front of the crankcase 12 with respect to a direction of travel of the watercraft so as to oppose the crankcase 12, and an intake manifold 23 which is connected to an outlet of the throttle body 22 and divided into branches so as to be connected to each of the intake ports 15 of the cylinders. The intake device 20 is fastened to the engine 4 with a portion of the intake manifold 23 closer to the throttle body 22 being bolted to a lateral side of the crankcase 12 while a downstream end of the intake manifold 23 being bolted to a lateral side of the cylinder head 14.
The individual intake pipes forked from the intake manifold 23 and connected to respective intake ports 15 are each attached with a fuel injection valve 24. The fuel injection valve 24 is arranged such that it projects out obliquely toward a lateral side of a head cover 25 attached to the cylinder head 14. As shown in Figure 1, the projecting ends of the fuel injection valves 24 are joined to a fuel rail 26 that extends vertically along the lateral side of the cylinder head 14.
As seen in Figure 3, the engine of the illustrated embodiment consists of a DOHC engine. As shown, an intake valve camshaft 31 serving as a driving cam shaft and a rocker arm 32 that oscillates following a cam 31a of the camshaft 31 are accommodated in the head cover 25. Further, an exhaust valve camshaft 33 and a rocker arm 34 that oscillates following a cam 33a of the camshaft 33 are also provided in the head cover 25. The camshafts 31, 33 and rocker shafts 32a, 34a for supporting the rocker arms 32, 34, respectively, are supported by a cam holder 53 which is secured by a bolt 52 onto a packing surface 51 of the cylinder head 14 on a side opposite to a combustion chamber 19. In this way, it is possible to sub-assemble the supporting structure of the camshafts 31, 33 easily.
In the shown embodiment, the fuel supply to each of the fuel injection valves 24 via the fuel rail 26 is canied out by a fuel supply system comprising a low pressure pump 28 attached to the head cover 25 and a high pressure pump consisting of an electromagnetic pump not shown in the drawing. The low pressure pump 28.may be implemented as a diaphragm-type pump which is attached to a lateral side of the head cover in an inclined attitude such that its push rod 28a extends toward the intake valve camshaft 31 obliquely downward when seen in Figure 3. The end of the push rode 28a slidably contacts the cam 31a so that in response to the cam rotation, the push rod 28a reciprocates back and forth to drive the low pressure pump 28.
An exhaust pipe 35 that serves as an exhaust device is attached to the cylinder head 14 so as to be in flow communication with the exhaust port 16. The exhaust pipe 35 is equipped with a water jacket 36 surrounding an exhaust passage 35a.
Further, a water temperature sensor 39 is attached to the exhaust pipe 35 to detect the water temperature of the water jacket 36 so that the detected temperature can be used in engine control. Within the water jacket 36 is disposed a sacrificial anode 37.
The sacrificial anode 37 is screwed onto a pillar-like portion 35b projecting from an outer wall of the exhaust pipe 35 into the water jacket 36. Further, the outer wall of the exhaust pipe 35 is formed with an opening 35c (Figure 4) at a position aligned with the sacrificial anode 37 in order to allow maintenance of the sacrificial anode 37, and a lad 15 38 is fastened to the opening 35c by a screw 54 to normally close the opening 35c.
Figure 4 shows an outer appearance of the side of the exhaust pipe 35. As shown in the drawing, the exhaust pipe 35 is formed with five bolt insertion holes 41. In this embodiment, the sacrificial anode 37 can be provided at two positions (see the numerals 35b, 35c in Figure 4), and two of the bolt insertion holes 41 are arranged near the two positions.
As shown in Figure 5, bolts 42 inserted into the bolt insertion holes 41 are screwed into threaded holes 14b which are provided at corresponding positions in the cylinder head 14 to fasten the exhaust pipe 35 to the cylinder head 14.
Between the mutually facing surfaces of the cylinder head 14 and the exhaust pipe 35 is interposed a gasket 43. The gasket is typically made of an electroconductive material such as a metal and coated with an electrically insulating material.
As shown in Figure 6, the gasket 43 is formed with holes 44 corresponding to the bolt insertion holes 41. Annular uncoated portions 43a are provided at portions of the gasket 43 surrounding two of the holes 44 located near the sacrificial anodes 37.
Front and rear surfaces of the gasket 43 (i.e., a surface facing the cylinder head 14 and a surface facing the exhaust pipe 35) are each applied with an electrically insulating surface treatment material, and the uncoated portions 43a where the electroconductive gasket material is exposed are formed by removing the coating at the portions surrounding the two holes 44.
In this way, when the exhaust pipe 35 is fastened to the cylinder head 14, they are electrically connected to each other via the uncoated portions 43a of the gasket 43.
Thus, even though the water jacket 36 in the exhaust pipe 35 and the water jacket 14a in the cylinder head 14 are not in flow communication with each other, the provision of the sacrificial anode 37 in the water jacket 36 of the exhaust pipe 35 can prevent rust development in the cylinder head 14.
It should be noted that in the shown embodiment, the sacrificial anodes 37 are disposed in the water jacket 36 of the exhaust pipe 35, but they may be disposed at appropriate position(s) within the water jacket 14a of the cylinder head 14.
In such a case also, the rust prevention effect of the sacrificial anode can be obtained both in the cylinder head 14 and in the exhaust pipe 35 because they are electrically connected to each other.
In the above embodiment, the sacrificial anodes 37 are screwed on the pillar-like portions 35b projecting into the water jacket 36. In this way, a larger surface area of the sacrificial anodes 37 exposed to the water body can be achieved compared with a case where the sacrificial anodes 37 are integrally attached to the lad 38, for example, and therefore, the sacrificial anodes 37 can be made more compact to achieve a given rust prevention effect and this can improve maintenanceability of the sacrificial anodes 37.
As described above, according to the present invention, even when the cylinder head and the exhaust device each having a water jacket are not connected to each other via the water jackets, electrical connection of the two component parts can allow a sacrificial anode provided for one of them to achieve rust prevention (or anti-corrosion) effect in both of them.
Particularly, when a gasket made of an electroconductive material coated with an electrically insulating material is interposed between the cylinder head and the exhaust device, the electrical connection can be achieved by providing an uncoated portion to the gasket such that the cylinder head and the exhaust device are electrically connected to each other via the uncoated portion. This can avoid complicating the structure and thus minimize the cost. Further, it will be preferred if the uncoated portion is provided so as to surround a bolt insertion hole formed in the gasket because this can place the uncoated portion at a part where a largest fastening pressure will be applied, thus achieving a reliable electrical connection.
Although the present invention has been described in terms of a preferred embodiment thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims.
Claims (2)
1. A rust prevention system of an outboard motor, comprising:
a cylinder head having a water jacket;
an exhaust device having a water jacket and fastened to said cylinder head;
and a gasket disposed between said cylinder head and said exhaust device, wherein said gasket is made of an electroconductive material coated with an electrically insulating material, wherein a sacrificial anode is disposed in one of said water jacket of said cylinder head and said water jacket of said exhaust device, and said cylinder head and said exhaust device are electrically connected to each other by electroconductive means, and said electroconductive means comprises an uncoated portion of said gasket provided around a bolt insertion hole formed in said gasket so that said cylinder head and said exhaust device are electrically connected to each other via said uncoated portion of said gasket.
a cylinder head having a water jacket;
an exhaust device having a water jacket and fastened to said cylinder head;
and a gasket disposed between said cylinder head and said exhaust device, wherein said gasket is made of an electroconductive material coated with an electrically insulating material, wherein a sacrificial anode is disposed in one of said water jacket of said cylinder head and said water jacket of said exhaust device, and said cylinder head and said exhaust device are electrically connected to each other by electroconductive means, and said electroconductive means comprises an uncoated portion of said gasket provided around a bolt insertion hole formed in said gasket so that said cylinder head and said exhaust device are electrically connected to each other via said uncoated portion of said gasket.
2. A rust prevention system of an outboard motor according to claim 1 wherein said sacrificial anode is disposed in said water jacket of said exhaust device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003-181009 | 2003-06-25 | ||
| JP2003181009A JP2005016380A (en) | 2003-06-25 | 2003-06-25 | Rustproofing device for outboard motor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2471993A1 CA2471993A1 (en) | 2004-12-25 |
| CA2471993C true CA2471993C (en) | 2008-06-10 |
Family
ID=33562248
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2471993 Expired - Fee Related CA2471993C (en) | 2003-06-25 | 2004-06-22 | Rust prevention system of an outboard motor |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2005016380A (en) |
| CA (1) | CA2471993C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6274384B2 (en) * | 2012-04-27 | 2018-02-07 | Nok株式会社 | Metal gasket and manufacturing method thereof |
| CN104775887A (en) * | 2015-04-09 | 2015-07-15 | 上海天纳克排气系统有限公司 | Exhausting system |
-
2003
- 2003-06-25 JP JP2003181009A patent/JP2005016380A/en active Pending
-
2004
- 2004-06-22 CA CA 2471993 patent/CA2471993C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2005016380A (en) | 2005-01-20 |
| CA2471993A1 (en) | 2004-12-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20130625 |