JP2792127B2 - Outboard motor intake passage structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake passage structure for an outboard motor.

(Prior Art) As shown schematically in FIG. 7, the outboard motor has an engine portion (a) at an upper portion and an under cover (b) located at a lower portion of an engine cover (b) covering the engine portion. A drive-shut housing (d) is connected to c), and a propeller (e) for propulsion is mounted below the housing (d). The rotation of the engine is transmitted to the propeller (e) to cause the propeller (e) to rotate. ) Is driven to rotate. The outboard motor is attached to a transom at the stern of the hull by a clamp bracket (f), and is rotatable counterclockwise in FIG. 7 around an axis (g). The propeller (e) can be tilted up to a position where the propeller (e) can be kept in the air when the hull is moored.

The engine intake system of this type of outboard motor is
As shown in the figure, a partial sectional view of the state at the time of tilting up,
An intake passage (k) is connected to a side surface of the crankcase (h) via a valve seal (j) of a reed valve (i), and a carburetor (l) and a silencer (m) are connected to the other end of the intake passage (k). ) Is connected, and the intake port (n) is opened at the end of the silencer (m).

(Problems to be Solved by the Invention) By the way, in the intake system of an outboard motor having the above-described structure, the reed valve (i) itself has poor sealing performance, so that the reed valve (i) is not provided in the crankcase (h) when tilted up. The accumulated liquid fuel, oil and the like (hereinafter referred to as gas) flow through the intake passage (k) to the carburetor (l) side, and flow out into the engine cover (b) and outside the cover (b), or into the ship. Gas will leak to The gas flowing out of the carburetor (l) is stored in the silencer (m) in the eighth position.
It accumulates as shown by the symbol (o) in the figure,
Gas accumulated in the silencer (m) easily leaks due to the position and shape of the intake port (n) of the silencer (m), incomplete sealing, and the like. Further, the gas accumulated in the silencer (m) often remains in the silencer (m) without being sucked into the engine even when the gas returns from the tilt-up state to the running state shown in FIG. .

In view of the above, the present invention provides an intake passage structure for an outboard motor in which gas does not flow from the crankcase side toward the carburetor and the silencer even when rotated to a tilt-up position, and leakage can be reliably prevented. To be.

(Means for Solving the Problems) In order to solve the problems of the prior art, the present invention relates to an outboard motor, which is provided on an inner wall surface of an intake passage communicating with a crankcase of an engine via a carburetor. A gas storage portion is provided on an inner wall surface which is sometimes a lower surface side, and the gas storage portion prevents a flow to the carburetor side when the engine is upright, and a lower surface portion which is inclined downward from the horizontal to the engine side when the engine is upright. And a flow preventing surface portion.

(Operation) When liquid gas or oil flows out of the crankcase to the intake passage side when the outboard motor is tilted up, it flows along the inner wall surface of the intake passage and flows into the gas reservoir formed on the inner wall surface. The carburetor is caught and is prevented from flowing toward the carburetor. When the outboard motor is returned to a state in which it can run, the lower surface of the gas storage portion is inclined downward to the horizontal or the crankcase side, so that the gas trapped in the gas storage portion travels through the lower surface portion. To the crankcase side.

Hereinafter, the present invention will be described with reference to examples shown in the drawings.

FIG. 1 shows a longitudinal section of a part of an engine section of an outboard motor to which the present invention is applied, and FIG. 2 shows a basic embodiment of an intake passage section according to the present invention.

In FIG. 1, reference numeral 1 denotes a crankcase, and cylinders 2 and 2 (in the figure, two cylinders are shown) are connected to one side of the crankcase 1.
The large ends of the connecting rods 6,6 of the pistons 5,5 are connected to the cranks 4,4 of the crankshaft 3, which is vertically supported inside.

On the other side of the crankcase 1, an intake passage inclined upward
7, 7 are connected via a valve seat 9 of a reed valve 8, and the other end of each of the intake passages 7, 7 is connected to a carburetor 10,
10 is connected, and the carburetors 10 and 10 have silencers 11
Is connected. The silencer 11 has an intake port 12 opened at one side below. These engine sections are covered by an engine cover 13, and a drive shut housing (not shown) is connected to a lower portion of the under cover 14.

The intake passage 7 in the present invention is provided with a gas reservoir 15 on the inner wall surface 7A. In the embodiment shown in FIG. 1, the gas storage portion 15 has an inner wall surface 7A which is a lower surface side when the engine is tilted in the intake passage 7 as shown in an enlarged view in FIG.
Is formed in a concave shape by recessing the lower surface portion 16 which is inclined horizontally or downward to the crankcase 1 side when the engine is upright.
And a flow preventing surface portion 17 for preventing flow toward the carburetor 10 at the time of tilting up.

Gasoline or lubricating oil that has not been completely vaporized easily adheres to the inner wall surface of the crankcase 1 during operation of the engine. After that, when the engine is stopped and the outboard motor is tilted up, these gases fill the gap of the reed valve 8. As a result, it may flow out of the hole of the valve seat 9 into the intake passage 7. The gas that has flowed into the intake passage 7 at the time of the tilt-up is captured by the gas reservoir 15 as shown in FIG. 3 and retained there, and is prevented from flowing toward the carburetor 10 by the flow prevention surface 17.

When the outboard motor is returned to the vertical posture again, the state shown in FIG. 2 is obtained, and the angle θ of the lower surface portion 16 of the gas storage portion 15 becomes 0 to a positive value, so that the gas is stored in the gas storage portion 15. The gas flowing along the lower surface 16 flows toward the crankcase 1 by gravity, and is not sucked into the engine and remains in the intake passage 7.

4 to 6 show a modified example of the gas reservoir 15 in the present invention. FIG. 4 shows an eave portion 18 projecting from the opening edge of the flow preventing surface portion 17 of the gas reservoir 15 in the above-described embodiment. The overhang 18 ensures that the outboard motor does not flow out to the carburetor 10 when the outboard motor is tilted up.

FIG. 5 shows that the gas storage portion 15 is provided with the inner wall surface 7A of the intake passage 7 not deformed, and one end of the reed valve-shaped plate piece 19 on the carburetor 10 side is fixed to the inner wall surface 7A with a screw 20 or the like. The inner wall surface 7A and the inner surface of the plate piece 19 form a gas storage section 15 having a substantially V-shaped cross section with the carburetor 10 side closed. In this case, the inner surface of the plate piece 19 constitutes the flow preventing surface portion 17, and a part of the inner wall surface 7A opposed thereto constitutes the lower surface portion 16. Note that the plate piece 19 may be formed integrally with the inner wall surface 7A instead of being a separate member.

FIG. 6 shows a state in which a cylindrical member 22 having a flange 21 interposed at a connection portion between the intake passage 7 and the carburetor 10 is fitted into an end of the intake passage 7, and an outer peripheral surface of the cylindrical member 22 and the intake passage 7. The cross section is substantially V with the carburetor 10 side closed between the inner wall 7A
A gas storage portion 15 having a character shape is formed. Also in this case, the outer peripheral surface of the cylindrical member 22 is
A part of an inner wall surface 7A of the intake passage 7 constitutes a lower surface portion 16.

Also in these embodiments, it is possible to store the gas flowing out from the crankcase 1 side when the outboard motor tilts up, prevent the gas from flowing to the carburetor 10 side, and return the gas to the crankcase 1 side when the engine is upright. it can.

〔The invention's effect〕

As described above, according to the present invention, even if gasoline, lubricating oil, or the like accumulated in the crankcase during operation of the engine flows out into the intake passage when the engine is stopped and tilted up after the engine stops, the engine is not operated when the engine is tilted. Since the gas is captured and stored in the gas storage section provided on the inner wall surface on the lower surface side, it can be prevented from flowing out to the carburetor side, and there is no problem that gas flows out into the silencer, under cover, and hull It can be. Further, the gas stored in the gas storage section is returned to the crankcase side by returning the outboard motor to the running state, and is sucked into the engine, so that there is no trouble due to the gas pool during operation. If the gas storage portion is formed by a concave portion, intake resistance hardly occurs, and there is no influence on engine output.

[Brief description of the drawings]

FIG. 1 is a side view showing a part of an engine part of an outboard motor to which the present invention is applied, FIG. 2 is an enlarged sectional view of an intake passage portion in FIG. 1, and FIG. 4 to 6 are sectional views of the modification, and FIGS.
The figure is a schematic side view showing an example of an outboard motor to which the present invention is applied,
FIG. 8 is a sectional view of a conventional intake passage, showing a state at the time of tilt-up. 1 ... Crankcase, 3 ... Crank shut, 7 ...
... intake passage, 10 ... carburetor, 11 ... silencer, 15
... gas storage part, 16 ... lower surface part, 17 ... flow prevention surface part.

Claims (1)

(57) [Claims] An engine is mounted on an upper part of an outboard motor body,
In an outboard motor having a propeller driven by the engine at the lower portion, the outboard motor body being steered and tiltably mounted on the hull, an inner wall surface of an intake passage communicating with a crankcase of the engine via a carburetor. A gas storage portion is provided on an inner wall surface which is a lower surface side when the engine is tilted up, the gas storage portion is a lower surface portion which is inclined downward from the horizontal to the engine side when the engine is upright, and a carburetor side when the tilt is raised. And a flow blocking surface for blocking flow to the outboard motor.