JPS6138144A - Water cooled type four-cycle engine in outboard engine unit - Google Patents

Abstract

PURPOSE:To make it possible to cool an engine in accordance with the temperature gradient of the engine, by forming a water jacket in the area extending from a combustion chamber to the axially intermediate section of a cylinder bore, and by forming the inlet and outlet passages in a cylinder head. CONSTITUTION:A water cooled four-cycle engine E comprises a crank casing attached to the upper surface of an extension casing 7 of an outboard engine unit and composed of an upper crank casing half 20a and a lower crank casing half 20b used as an oil pan, a cylinder block 22 connected to one side of the upper crank casing half 20a and a cylinder head 23 connected to one end face of the block 22. In this arrangement, a continuous water jacket 32 is formed in the cylinder block 22 and the cylinder head 23 such that the water jacket 32 is formed in the area extending from a combustion chamber 27 to the axially intermediate section of a cylinder bore 22a. Further, the inlet an outlet passages 32a, 32b of the water jacket 32 are formed in the cylinder head 23.

Description

Detailed Description of the Invention A1 Objective of the Invention (11 Industrial Field of Application) The present invention relates to a water-cooled four-stroke engine for an outboard motor, in particular,
A crankcase that is attached to the top surface of an extension case of an outboard motor and stores lubricating oil at the bottom; a cylinder block that is connected to the crankcase and has a cylinder hole in which a piston slides; and an end surface of the cylinder block. and a cylinder head having a combustion chamber, the cylinder block and cylinder head forming a series of water jackets surrounding the cylinder and the combustion chamber, the water jackets having an inlet passageway for directing external water. It relates to a system in which the water supply pipe is connected and the outlet passage of the water jacket is opened to the outside.

(2) Conventional technology Conventionally, in such a four-cycle engine, a water jacket was formed in a wide area extending from the combustion chamber to the lower part of the cylinder hole, and the inlet passage of the water jacket was provided in the crankcase (for example, (Refer to Publication No. 58-43895)
.

(3) Problems to be solved by the invention In this type of engine, the water jacket is always supplied with cold water such as seawater as cooling water, so if a conventional water jacket and its inlet passage are used, , cold water flows into the photon inlet passage and cools the crankcase, which is relatively difficult to heat, resulting in a supercooled crankcase, which delays the temperature rise of the lubricating oil inside it and prolongs warm-up. A problem arises.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a four-cycle outboard engine in which the crankcase is not overcooled and warm-up operation is promoted.

B1 Structure of the Invention (1) Means for Solving the Problems The present invention provides that the water jacket is formed in an area from the combustion chamber to the axially intermediate portion of the cylinder hole, and that the inlet passage and the outlet passage are connected to the cylinder hole. It is characterized by being formed on the head.

(2) Function External water such as seawater supplied through the water pipe is introduced into the water jacket of the cylinder head and cylinder block through the inlet passage of the cylinder head, and after passing through it, the water is introduced into the water jacket of the cylinder head and the outlet passage of the cylinder head. After that, it is discharged to the outside.

Therefore, since cooling water flows into and out of the water jacket through the inlet and outlet passages formed in the cylinder head, the flow of cooling water is intense in the water jacket around the combustion chamber, and around the cylinder holes. The flow of cooling water is slow in the water jacket, and the water jacket around the cylinder hole ends in the axial middle of the cylinder hole, so cooling is carried out according to the temperature gradient of the engine, which becomes hot toward the combustion chamber. This prevents overcooling of the crankcase.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.
is arranged so that the crankshaft 1 is vertical, and the rotational torque of the crankshaft 1 is transmitted to the horizontally arranged propeller shaft 4 via the vertically arranged drive shaft 2 and bevel gear transmission 3,
The propeller 5 is driven to rotate.

An extension case 7 for accommodating the drive shaft 2 in a hollow portion 7a is connected to the lower surface of the engine E, and a gear case 8 for accommodating the bevel gear transmission 3 in an oil-tight manner is connected to the lower surface of the case 7. Ru.

A pair of upper and lower extension brackets 9°9' projecting forward are attached to the extension case 7 via elastic support members 10 and 10. It is steerably connected to the swivel case 12 via the swivel case 11 . Further, the swivel case 12 is connected via a horizontal pivot 4 to the upper part of a pair of left and right stern brackets 13.13 which are detachably fixed to the stern plate Sa of the hull S by a clamper 17 so as to be tiltable in the vertical direction.

A handle bracket 15 is integrally formed with the upper extension bracket 9, and a steering handle 1-6 is pivotally attached to this.

As shown in FIG. 2, the main body of the engine E includes an upper crankcase 20a that supports the upper end of the crankshaft l, and an upper crankcase 20a that is connected to the lower surface of the crankcase 20a and supports the lower end of the crankshaft 1. A lower crankcase 20b, a cylinder block 22 in which a piston 21 connected to the crankshaft 1 slides into a cylinder hole 22a, a cylinder head 23 connected to an end surface of this cylinder block 22, and a lower surface of the cylinder head 23. The cylinder block 22 is composed of an exhaust passage block 35 which is polymerized via a gasket 36 and fixed with POL) B+, and the cylinder block 22 is connected to the hull S.
It is formed integrally with the upper crankcase 20a at a position facing rearward. The lower crankcase 20b stores lubricating oil and is also used as an oil pan.

A ring gear 25 for starting is fixed to the lower surface of the flywheel 24 fixed to the upper end of the crankshaft 1, and a coil starter 26 for driving the ring gear 25 is attached to the front wall of the upper crankcase 20a.

The cylinder head 23 includes a combustion chamber 27 that faces the upper end surface of the piston 21, and an intake boat 2 that opens into the combustion chamber 27.
8 and an exhaust port 29 are formed, and an outlet 29a of the exhaust port 29 is opened to the cylinder and to the lower surface of the throat 23. The suction and exhaust ports 28 and 29 are opened and closed by suction and exhaust valves 30 and 31.

Also, the cylinder block 22 and the cylinder throat 23
A series of cooling water jackets 32 are formed in the area from the combustion chamber 27 to the axially intermediate portion of the cylinder hole 22a, and the inlet passage 32a and outlet passage 32b of this water jacket 32 are connected to the cylinder head 23. The cylinder head 2 is drilled in the cylinder head 2 along with the exhaust port 29.
It is opened on the lower surface of 3.

It is preferable that the end of the water jacket 32 on the cylinder block 22 side ends at the piston pin 21a of the piston 21 at its upper limit, as shown in FIG.

A thermostat T is installed at the top of the cylinder head 23 to control communication and interruption between the water reservoir throat 32 and the outlet passage 32b.

The exhaust passage block 35 has an exhaust passage 33 connected to the exhaust port 29, and the exhaust passage 33 is connected to the lower crankcase 2.
It has a release shape with a bulging portion 33a bulging toward the 0b side.

In addition, as shown in FIGS. 3 to 5, the exhaust passage block 35 includes a person in the water tank/throat 32 and an outlet passage 32a.
, 32b, respectively. a, 34b
These are formed together with the exhaust passage 33 when the exhaust passage block 35 is cast.

On the other hand, as shown in FIGS. 2 and 6, an extension part 37 that projects rearward is integrally connected to the upper end of the extension case 7, and this extension part 37 includes the exhaust passage 33 and the extension part 37. A drain channel 38 that opens the drain channel 34b to the hollow portion 7a of the extension case 7, and a drain chamber 43 connected to the bypass 39 are formed.
A notch-shaped bypass outlet 39a that opens into the exhaust passage 38 toward the exhaust passage 33 is provided on the upper surface of the side wall of the cylinder, and a water test hole 44 that opens to the outside is provided on the bottom wall thereof.

The lower surface of the exhaust path block 35 is the lower crankcase 20b.
The upper surface of the extension part 37 is flush with the lower surface of the extension case 7, and the upper surface of the extension part 37 is flush with the upper surface of the extension case 7. Between these opposing surfaces, there are a series of partition plates 41 made of stainless steel and a wire plate. A pair of overlapping gaskets 42a and 42b are interposed on both the upper and lower surfaces of 41, and the lower crankcase 20b and extension case 7 are connected to the bolt B2.
Accordingly, the exhaust path block 35 and the extension portion 37 are connected by bolts B3.

As shown in FIGS. 2 and 7, the partition plate 41 has a first through hole 46 through which the drive shaft 2 passes. and a mounting hole 47 into which a grommet-like elastic joint 45 made of rubber is mounted;
A second through hole 46 communicating between the bypass 39 and the drainage chamber 43
2, a third through hole 463 that communicates between the bulging part 33a of the exhaust passage 33 and the exhaust passage 38, and the drainage passage 34b and the exhaust passage 38.
A fourth through hole 464 communicating therebetween is bored. and,
A portion of the partition plate 41 between the first and third through holes 461 and 462 is a first partition wall 48 that protrudes into the hollow portion 7a of the extension case 7 and approaches the drive shaft 2. The part between the third and fourth through holes 463 and 464 is
The second partition wall 48□ separates the space between the exhaust passages 33 and the drainage passages 34b by a distance greater than the thickness of the partition wall between the exhaust passages 33 and the drainage passages 34b.

The upper end of the elastic joint 45 attached to the partition plate 41 is tightly fitted to the water supply channel 34a, and the upper end of the water pipe 40 running vertically in the hollow part 7a of the extension 7 is tightly fitted to the hollow part of the joint 45. In this way, the water pipe 40 and the water supply channel 34a are communicated with each other.

Referring again to FIG. 1, the gear case 8 is provided with a plurality of small water intake ports 50 on its side and a discharge port 51 at its rear. Furthermore, the gear case 8 has a drive shaft 2.
A water pump 52 driven by is installed, the water intake port 50 is connected to the suction side of the water pump 52, and the lower end of the water pipe 40 is fixed to the discharge side of the water pump 52.

In FIG. 2, 53 is a water seal installed between the lower part of the lower crankcase 20b and the crankshaft 1 passing through it, and 54 is an engine cover.

Next, the operation of this embodiment will be explained.

While the engine E is running, the water pump 52 driven by the drive shaft 2 sucks in external water, for example seawater, from the water intake port 50 and pumps it into the water pipe 40. Therefore, if the engine is in a cold state, the thermostat T is closed. A valve is used to shut off the water jacket 32 and the outlet passage 32b. Therefore, water pipe 4
Although the water pressure-fed into the water supply channel 34a enters the water supply channel 34a, it immediately moves from the bypass 39 to the drain chamber 43, and then passes through the bypass outlet 39.
a and is discharged from the water inspection hole 44. Therefore, since water does not flow in the water jacket 32, the engine E<7
) warm-up is promoted.

The water that has exited the bypass outlet 39a flows down from the discharge path 38 into the hollow part 7a of the extension case 7, and flows through the discharge port 51.
is discharged to the outside. Further, the water coming out of the water inspection hole 44 catches the eye of the operator, thereby confirming the operating state of the water pump 52.

When the engine E warms up and the thermostat T opens, most of the water sent from the water pipe 40 to the water supply channel 34a enters the water jacket 32 from the inlet passage 32a of the cylinder head 23, and some of the water flows out to the bypass 39 as before.

The water that has entered the water jacket 32 is transferred to the cylinder head 23.
After cooling the cylinder block 22, it passes through the thermostat T, passes through the outlet passage 32b of the cylinder head 23, flows down to the water channel 34b, the discharge passage 38, and the hollow portion 7a, and is discharged to the outside through the discharge port 51.

In this way, the cooling water flows into and out of the water jacket 32 through the inlet and outlet passages 32a and 32b formed in the cylinder head 23, so the cooling water flows in and out of the water jacket 32 around the combustion chamber 27. The flow is intense, and the flow of cooling water is slow in the water jacket 32 around the cylinder hole 22a.Moreover, the water jacket 32 around the cylinder hole 22a ends at the axial middle part of the cylinder hole 22a, so it flows toward the combustion chamber 27. Cooling is performed according to the temperature gradient number of the engine E, which reaches a high temperature, and the crankcase 20
Overcooling of a and 20b is avoided.

On the other hand, the exhaust gas discharged from the combustion chamber 27 of the engine E to the exhaust boat 29 passes through the exhaust passage 33 and then passes through the exhaust passage 33.
8 and moves to the hollow parts 7a-i, m of the extension case 7 while coming into contact with the cooling water and dropping in temperature, so even if it comes into contact with the drive shaft 2, etc., it will not overheat them. Further, since the first partition wall 481 is disposed above the downstream opening of the discharge passage 38, the partition wall 48I prevents the exhaust gas from flowing upward, thereby protecting the water seal 53 from the high-temperature exhaust gas. .

The exhaust gas that has moved into the hollow part 7a of the extension case 7 flows downward and is discharged to the outside from the discharge port 51 together with the cooling water.

C4 Effects of the Invention As described above, according to the present invention, the water jacket is formed in the area from the combustion chamber to the axially intermediate portion of the cylinder hole, and the inlet passage and the outlet passage are formed in the cylinder head.
Cooling water can be supplied to the water jackets of the cylinder block and cylinder head without going through the crankcase, and cooling can be performed according to the temperature gradient of the engine, so external cold water is always used as the cooling water. This prevents overcooling of the crankcase, promotes proper temperature rise of the lubricating oil, and shortens engine warm-up time.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partially longitudinal side view of an outboard motor, Fig. 2 is an enlarged longitudinal side view of the engine section, and Fig. 3 is taken along m-m of Fig. 2. Figure 4 is a cross-sectional view taken along the line IV-mV in Figure 3, Figure 5 is a cross-sectional view taken along the line V-v in Figure 2, Figure 6 is a plan view of the extension case, and Figure 7 is a partition plate. FIG. E... Engine... Crankshaft, 2... Drive shaft, 4... Propeller shaft, 7... Extension case, 7a... Hollow part, 20a... Upper crank case, 20b...・Lower crankcase as oil pan, 22... Cylinder block, 22a... Cylinder hole, 23... Cylinder head, 27... Combustion chamber, 32... Kent under water, 32a... Entrance passage, 32b...exit passage,
33... Exhaust path, 34a... Supply channel, 34b...
Drainage channel, 35...Exhaust channel block, 38...Drainage channel, 40...Water pipe, 43...Drainage chamber, 44...Water inspection hole, 50...Water intake,! 71... discharge port, 52...
・・Water pump

Claims (1)

[Claims] A crankcase that is attached to the top surface of an outboard motor extension case and stores lubricating oil at the bottom; a cylinder block that is connected to one side of the crankcase and has a cylinder hole into which a piston slides; a cylinder head connected to an end face and having a combustion chamber, the cylinder block and the cylinder head forming a series of water jackets surrounding the cylinder and the combustion chamber, the inlet passage of the water jacket being connected to external water. In an outboard water-cooled four-stroke engine, the water pipe that supplies water is connected and the water jacket outlet passage is opened to the outside.
A water-cooled four-stroke engine for an outboard motor, characterized in that the water jacket is formed in an area from the combustion chamber to an axially intermediate portion of the cylinder hole, and the inlet passage and the outlet passage are formed in the cylinder head. .