JPH11193760A - Fuel vapor separator in outboard boat engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the intake of fuel vapor into the engine and maintain normal exhaust characteristics at all times by expelling the fuel vapor, which is generated in the auxiliary fuel tank that collects excess fuel circulating from the fuel injection valve, outside the engine compartment through a coupling protruding from the air vent pipe and the lower portion of the case. SOLUTION: In an outboard engine, a four cylinder engine is arranged upright on top of an engine support body 2 of the upper portion of an extension case 1. Fuel sucked from a main fuel tank in the boat via a fuel supply pipe is fed to an auxiliary fuel tank by means of a low pressure fuel pump. This auxiliary fuel tank collects excess fuel circulating from a fuel injection valve 94, and is such that it separates the fuel vapor from the stored fuel. To the upper cavity portion in the auxiliary fuel tank is connected an air vent pipe 120. The outside end of this air vent pipe 120 is connected to a coupling 122 protruding from the lower portion of the case C, including the engine support body 2, thereby enabling to exhaust the fuel vapor outside the engine compartment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for driving a drive shaft mounted on an engine support coupled to an upper end of an extension case for housing a drive shaft for driving a propeller shaft. The present invention relates to an outboard motor including a lower case including an engine support, and an engine cover detachably attached to the lower case. And an auxiliary fuel tank for separating fuel vapor from stored fuel, and an air vent pipe communicating with an upper space inside the auxiliary fuel tank, the auxiliary fuel tank being connected to the auxiliary fuel tank. .

[0002]

2. Description of the Related Art In such a conventional fuel vapor separation device for an outboard motor, an air vent pipe extending from an auxiliary fuel tank is opened into an intake system of an engine (for example, see Japanese Unexamined Patent Publication No. 4-29-29).
No. 5172) or open directly to the engine room.

[0003]

The auxiliary fuel tank is located adjacent to the engine and is susceptible to the heat generated, and the excess fuel recirculated from the fuel injection valve side has a high temperature. The inside becomes high temperature and fuel vapor is generated. Thus, when the air vent pipe of the auxiliary fuel tank is opened into the intake system of the engine, the fuel vapor generated in the auxiliary fuel tank is mixed with the air in the engine room sucked by the engine, and the air vent pipe Is opened to the engine cover together with the air in the engine cover, the air-fuel ratio of the air-fuel mixture generated in the combustion chamber of the engine is equal to the added fuel vapor in any case. However, there is a possibility that the exhaust characteristics of the engine will be somewhat deteriorated.

The present invention has been made in view of such circumstances, and provides a fuel vapor separation device for an outboard motor in which fuel vapor generated in an auxiliary fuel tank is prevented from being sucked into an engine. With the goal.

[0005]

In order to achieve the above object, the present invention provides an engine for driving a drive shaft on an engine support which is coupled to an upper end of an extension case for accommodating a drive shaft for driving a propeller shaft. In an outboard motor comprising an engine room accommodating the engine and a lower case including an engine support, and an engine cover detachably attached to the lower case, the engine An auxiliary fuel tank that receives excess fuel that recirculates from the injection valve side and separates fuel vapor from stored fuel is provided, and the inner end of an air vent pipe that communicates with the upper space inside the auxiliary fuel tank is connected to this auxiliary fuel tank. A joint is formed in the lower case and faces the engine room and projects outside the extension case. That connect the outer end of the vent tube to the first feature.

According to the first feature, the fuel vapor generated in the auxiliary fuel tank is discharged out of the engine room through the air vent pipe and the joint protruding from the lower case. Therefore, the fuel vapor is not sucked into the engine, so that the exhaust characteristics can be kept normal. Moreover, since the joint is provided in the lower case, the air vent pipe can be easily attached to and detached from the lower case when the engine cover is open, and the air vent pipe does not hinder the attachment and detachment of the engine cover.

According to the present invention, in addition to the first feature, a cover member for covering at least a part of the lower case is attached to the lower case, and the joint is opened in an empty space defined between the cover member and the lower case. This is a second feature.

According to the second feature, it is possible to secure the breathing action of the auxiliary fuel tank by the air vent pipe while preventing the splash of the waves from entering the air vent pipe by using the cover member of the lower case.

Further, the present invention has a third feature in that, in addition to the first or second feature, a condensing means for condensing fuel vapor is provided in the middle of the air vent pipe.

According to the third feature, the fuel vapor flowing from the auxiliary fuel tank to the air vent can be captured and condensed by the condensing means, and can be returned to the auxiliary fuel tank.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 15 show an embodiment of the present invention. FIG. 1 is an overall side view of an outboard motor, and FIG.
2 is an enlarged cross-sectional view of FIG. 3, FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2, and FIG.
5 is a sectional view taken along line 5-5 of FIG. 3, FIG. 6 is an enlarged sectional view of a main part of FIG. 3, FIG. 7 is a view taken along arrow 7 of FIG. 6, and FIG. 9, 10, 11 and 12 are arrows 9-9, 10-10, 11-11 and 12-of FIG. 7.
13 is an enlarged sectional view taken along line 13-13 of FIG. 3, FIG. 14 is an enlarged sectional view taken along line 14-14 of FIG. 3, and FIG. 15 is a circuit diagram of the cooling water.

Referring to FIG. 1, an outboard motor O as a power unit includes a mount case 2 as an engine support coupled to an upper portion of an extension case 1, and a water-cooled in-line four-cylinder 4 is provided on an upper surface of the mount case 2. The cycle engine E is supported with the crankshaft 15 placed vertically.

As shown in FIGS. 1, 3 and 13, the mount case 2 is provided with a flange 2a on the outer periphery thereof, and an extension case 3 having an upper surface opened on the upper surface of the flange 2a is provided with a seal member 31. And an engine cover 4 is detachably mounted on the upper part of the extension case 3.

The mount case 2 and the extension case 3 constitute a lower case C that covers the lower part of the engine E. The lower case C and the engine cover 4 make up an engine room 36 for accommodating the engine E. Is defined.

In order to cover the outer peripheral surface of the mount case 2,
An annular undercover 5 (cover member) is attached between the extension case 3 and the extension case 1. That is, the under cover 5 is made of an elastic synthetic resin, and has one abutment 5a at the front. When attaching the under cover 5, first, the extension case 3
The opening 5a of the extension case 1 is widely opened, the under cover 5 is arranged so as to surround the mount case 2, and the annular step 1a formed on the outer periphery of the upper part of the extension case 1.
The lower end of the under cover 5 is engaged with the extension case 3, and the upper end of the under cover 5 is connected to the extension case 3 by a tap screw 33. Further, the joint ends are fastened with bolts 32 so as to close the joint 5a of the under cover 5.
Thus, the under cover 5 covers the mount case 2, forms a continuous surface that connects the outer peripheral surfaces of the extension case 3 and the extension case 1, and has an annular space between the under cover 5 and the outer peripheral surface of the mount case 2. A chamber 34 is defined. The vacant chamber 34 communicates with the atmosphere via a notch 5b provided above the abutment 5a of the undercover 5.

Referring again to FIG. 1, the engine E includes a cylinder block 6, a crankcase 7, a cylinder head 8,
A head cover 9, a lower belt cover 10, and an upper belt cover 11 are provided, and the lower surfaces of the cylinder block 6 and the crankcase 7 are supported on the upper surface of the mount case 2. A piston 13 is slidably fitted to each of the four cylinders 12 formed in the cylinder block 6, and each piston 13 is connected to a vertically disposed crankshaft 15 via a connecting rod 14.

The flywheel 1 is provided at the lower end of the crankshaft 15.
The drive shaft 17 connected with the extension case 6 extends downward inside the extension case 1, and the lower end thereof is connected to the gear case 18.
Is connected to a propeller shaft 21 having a propeller 20 at the rear end via a bevel gear mechanism 19 provided inside the. A lower end of a shift rod 22 is connected to a front portion of the bevel gear mechanism 19 so as to switch the rotation direction of the propeller shaft 21.

A pair of left and right upper arms 2 connected to the mount case 2 via upper mount rubbers 23a.
3 and extension case 1 with lower mount rubber 2
A swivel shaft 25 is fixed between a pair of left and right lower arms 24 connected through the 4a. A swivel case 26 that rotatably supports the swivel shaft 25 is attached to a stern bracket 27 attached to the stern S. Tilt axis 28
Is supported so as to be able to swing vertically. At this time, as shown in FIG. 4, the upper arm 23 is disposed so as to pass through the notch 5b of the under cover 5.

An oil pan 29 housed in the extension case 1 and an exhaust pipe 3
0 is combined. The exhaust gas discharged from the exhaust pipe 30 into the internal space of the extension case 1 is
Is discharged into water through the hollow portion of the boss.

As is apparent from FIG. 2, the engine E accommodated in the engine room 36 has two secondary balancer shafts 37 and 38 arranged in parallel with the crankshaft 15 and 1
And a plurality of camshafts 39. Secondary balancer shaft 37,3
8 is supported by the cylinder block 6 closer to the cylinder head 8 than the crankshaft 15, and the camshaft 39 is supported between the mating surfaces of the cylinder head 8 and the head cover 9.

At the upper end of the crankshaft 15, a pulley assembly 44 in which a camshaft drive pulley 40, a secondary balancer shaft drive pulley 41, a generator drive pulley 42, and a cooling fan 43 are integrated is fixed. The camshaft driven pulley 45 fixed to the upper end of the camshaft 39 and the camshaft driving pulley 40 are connected by an endless belt 46. Camshaft drive pulley 40
Is set to one half of the diameter of the camshaft driven pulley 45, so that the camshaft 39 rotates at half the speed of the crankshaft 15. Arm 4 pivoted by pin 47
A tension pulley 49 provided at one end of the endless belt 8 is pressed against the outer surface of the endless belt 46 by the resiliency of a spring 50, thereby applying a predetermined tension to the endless belt 46.

A pair of secondary balancer shaft driven pulleys 52, 5 fixed to an intermediate shaft 51 provided near one secondary balancer shaft 37 and the other secondary balancer shaft 38, respectively.
3 and the secondary balancer shaft driving pulley 41 are connected by an endless belt 54. A tension pulley 57 provided at one end of an arm 56 pivotally supported by a pin 55 is pressed against the outer surface of the endless belt 54 by the resilience of a spring 58, whereby a predetermined tension is applied to the endless belt 54. . Intermediate shaft 52 and one secondary balancer shaft 3
7 is connected by a pair of gears (not shown) having the same diameter, and the diameter of the secondary balancer shaft driving pulley 41 is 2
The diameter is set to twice the diameter of the secondary balancer shaft driven pulleys 52, 53, and therefore, a pair of secondary balancer shafts 37, 3
Reference numeral 8 rotates in opposite directions at twice the speed of the crankshaft 15.

Two bolts 5 are provided on the upper surface of the crankcase 7.
The generator 62 is supported by the two bolts 61 on the bracket 60 fixed at 9. A generator driven pulley 64 fixed to a rotating shaft 63 of a generator 62 and the generator driving pulley 42
Are connected by an endless belt 65, and the crankshaft 15
Drives the generator 62. Thus, the generator 62
Provided separately from the engine E, it is possible to use a general-purpose generator 62 as compared with a case where the generator is incorporated in a flywheel provided on the crankshaft 15, which is advantageous in cost. Moreover, the capacity of the generator 62 can be easily increased.

Cam shaft 39, secondary balancer shafts 37, 38
And three belts 46, 54, 6 for driving the generator 62
5 is a lower belt cover 10 and an upper belt cover 11
Is housed in the belt chamber 68 defined by. Together with the lower belt cover 10 has an opening 10 ₁ surrounding the periphery of the generator 62 includes a plurality of slits 10 ₂ in the right side of the bottom wall of the crank shaft 15, through these openings 10 ₁ and the slits 10 ₂ Thus, air is introduced into the belt chamber 68.

2 to 4, a pair of left and right slit-shaped rear openings 4 ₁ are provided on the upper rear surface of the engine cover 4.
There is formed a guide plate 75 which front end in the front-rear direction intermediate portion of the engine room 36 extending from the lower edge of the rear opening 4 ₁ forward is fixed to the inner surface of the engine cover 4. At the time of fixing, the rear edge of the guide plate 75 is fixed to the inner surface of the engine cover 4 by the tap screw 73, and the boss 75 a at the intermediate portion is fixed by the tap screw 74. This guide plate 75, draining step portion 75 ₁ of the two-stage rising stepwise towards the rear opening 4 ₁ in the engine compartment 36, 75 ₂ are formed.

Thus, the rear opening 4₁Sky inhaled from
The air is sandwiched between the upper wall of the engine cover 4 and the guide plate 75.
Flows forward through the space, and the two-stage draining step 75₁,
75 _TwoGoing up. At that time, the flight contained in the air
Spray is draining step 75₁, 75 _TwoI will be stopped from progressing
And only air is drained₁, 75_TwoPass through
Will flow into the engine room 36 and the engine E
It is used for intake and cooling of each part.

Next, the structure of the intake system of the engine E will be described with reference to FIGS.

An intake silencer 76 is fixed to the front of the crankcase 7 with three bolts 77. The intake silencer 76 includes a box-shaped main body 78 and a duct 79 connected to a left side surface of the main body 78. The duct portion 79 has an intake opening 79 ₁ that opens downward at the lower end thereof.
Provided with a, and a communicating hole 79 ₂ communicating with the internal space of the main body portion 78 at its upper end. Throttle body 80 arranged on the right side of main body 78 of intake silencer 76
Is connected to the main body 78 via a flexible short air intake duct 35.

The throttle body 80 is connected and fixed to an intake manifold 85 described below. Elbow 81, surge tank 82, and four intake pipes 83a, 83b, 83
An intake manifold 85 integrally provided with c and 83d and a mounting flange 84 is arranged along the right side of the engine E. The elbow 81 changes the flow of intake air from a flow along the front surface of the crankcase 7 to a flow along the right side surface of the crankcase 7 by approximately 90 °, and may be a duct having flexibility. In this embodiment, the surge tank 82, the intake pipes 83a, 83b, 83c, 83d and the mounting flange 8 are provided for supporting and fixing the throttle body 80.
4 and one.

The elbow 81 and the support of the intake manifold 85
The connection part of the surge tank 82 is the upper end of the surge tank 82
And the size is smaller in the vertical direction than the lower end.
And the bolt 86₁, 86_TwoWith a loose hole
Two brackets 86_ThreeAnd the crankcase 7
Is fixed to the right side wall of the
A bolt 87 is formed on the right side surface of the cylinder head 8 by a bolt 87.
Air manifold mounting surface 8 ₁Fixed to

Next, the structure of the fuel supply device for the engine E will be described with reference to FIGS.

A low-pressure fuel pump 88 composed of a plunger pump is provided on the rear surface of the head cover 9. The low-pressure fuel pump 88 connects a fuel supply pipe L ₁ from a main fuel tank (not shown) installed in the ship. the fuel sucked through is supplied to the auxiliary fuel tank 89 is disposed on the right side of the engine E through the low pressure fuel filter and the fuel supply pipe L ₂ (not shown). As shown in FIG. 5, a pump drive rocker arm 103 is coaxially supported on an intake rocker arm shaft 102 supporting an intake rocker arm 101, and one end of the pump drive rocker arm 103 is provided on the cam shaft 39. The other end is engaged with the plunger 105 of the low-pressure fuel pump 88 while being engaged with the pump cam 104. As a result, the low-pressure fuel pump 88
9 driven.

As shown in FIGS. 6 to 12,
The auxiliary fuel tank 89 is a lower tank body 89₁And its
Upper cap 89 bonded to the upper end_TwoAnd split into two
Yes, tank body 89₁The first block extending long backward
Racket 130₁And a relatively short second protrusion protruding forward.
Racket 130_TwoAnd a relatively short third protrusion protruding upward.
Racket 130_ThreeAre integrally formed. These braquets
130₁, 130 _Two, 130_ThreeThe mounting hole at the tip
Each of the elastic grommets 131 is attached,
The first and second brackets 13 via the helmet 131
0₁, 130_TwoIs the fourth intake pipe 83d and the cylinder blow
First and second mounting bosses 132 formed on the hook 6₁, 13
2_TwoBolt 129₁, 129_TwoInstalled by each
The third bracket 131 is provided with a surge tank 82.
Is supported by a support pin 133 protruding from the side surface. Bullet above
Grommet 131 is provided from engine E to auxiliary fuel tank
To prevent vibration transmission to 89 and to suppress heat conduction
Can be.

Inside the auxiliary fuel tank 89, a float valve 90 for adjusting the level of the stored fuel is accommodated. The float valve 90 includes a shutoff valve 108 to the fuel supply pipe L ₂ extending from the low pressure fuel pump 88 is provided in a portion that is connected to the auxiliary fuel tank 89, the on-off valve to lift to follow the fuel level And a float 109 for opening and closing the opening 108. When the fuel level drops below a prescribed level, the on-off valve 108 opens to open the low-pressure fuel pump 88.
Is introduced into the auxiliary fuel tank 89 and rises above a prescribed level, the on-off valve 108 closes to shut off the reception of fuel from the low-pressure fuel pump 88.

Attached to the auxiliary fuel tank 89 are a high-pressure fuel pump 91 having an axis extending in the front-rear direction immediately below the tank, and a high-pressure fuel filter 92 having an axis extending in the up-down direction immediately after the tank.

The high-pressure fuel pump 91 is entirely covered with a cylindrical heat insulating material 234 formed by abutting a pair of semi-cylindrical bodies 134a and 134b. In the case of the illustrated example, the heat insulating material 134 is formed by molding a laminate of a nonwoven fabric and a foamed melamine resin. A pair of front and rear annular grooves 135 are formed on the heat insulating material 134 with the central thick portion interposed therebetween, and a rubber band 137 is wound around each annular groove 135, and a steel plate mounting engaged with the outer periphery thereof is provided. Band 13
6, the high-pressure fuel pump 91 is fastened and attached to the outer surface of the bottom wall of the auxiliary fuel tank 89. That is, a pair of front and rear hook engaging portions 138 is provided on one lower side of the auxiliary fuel tank 89.
In addition, a pair of front and rear mounting bosses 139 are integrally formed on the other side of the lower portion, and the hook 136a at one end of each mounting band 136 is engaged with the corresponding hook engaging portion 138, and each mounting band 136 is formed. Is fixed to the corresponding mounting boss 139 with a bolt 140, so that the high-pressure fuel pump 91 is fastened to the outer surface of the bottom wall of the auxiliary fuel tank 89. By disposing the high-pressure fuel pump 91 immediately below the auxiliary fuel tank 89 in this manner,
A fuel outlet pipe 141 protruding from the front surface of the bottom and a fuel inlet pipe 91i protruding from the front end face of the pump 91 are arranged close to each other, and they are connected by a low-pressure fuel pipe 143 as short as possible.

The high-pressure fuel filter 92 is connected to the auxiliary fuel tank 8
Attached to the first outer surface of the bracket 130 ₁ 9.
That is, the first bracket 130 ₁ has the mounting boss 145 and the hook engaging portion 146 formed before and after, and the steel plate mounting band 148 engaged with the outer periphery of the high-pressure fuel filter 92 via the rubber band 147. Hook 148a at one end
The while engaged with the hook engaging portion 146, by fixing to the mounting boss 145 at the other end the bolt 149, the high-pressure fuel filter 92 is clamped to the first outer surface of the bracket 130 ₁ of the auxiliary fuel tank 89 . Thus, the fuel outlet pipe 91o projecting from the rear end face of the high-pressure fuel pump 91 and the fuel inlet pipe 92i projecting from the lower end face of the high-pressure fuel filter 92 are arranged close to each other. It is connected by a short high-pressure fuel pipe 144.

Thus, the high pressure fuel pump 91
34, immediately after the operation of the engine E is stopped, even if the ambient temperature inside the engine cover 4 temporarily rises,
Heating of the atmosphere due to high heat can be avoided, bubbles are prevented from being generated in the fuel remaining inside the pump, and fuel can be appropriately supplied to the fuel injection valve 94 when the engine E is restarted. it can.

Mounting flange 84 of intake manifold 85
The, the fuel rail 93 is fixed by a plurality of bolts 113, four cylinders 12 are to four fuel injection valves 94 is fixed corresponding to the fuel supply pipe L ₄ from the high-pressure fuel filter 92 The fuel supplied to the lower end of the fuel rail 93 is distributed to the four fuel injection valves 94. A regulator 95 provided at the upper end of the fuel rail 93 adjusts the pressure of the fuel supplied to the fuel injection valve 94,
The excess fuel through the return pipe L ₅ fuel auxiliary fuel tank 8
Reflux to 9. To adjust the set pressure of the regulator 95, the regulator 95 and the surge tank 82 is connected through a negative pressure pipe L _6.

When assembling the engine E,
A high-pressure fuel pump 91 and a high-pressure fuel filter 92 are previously attached to an auxiliary fuel tank 89 in an auxiliary assembly line to constitute a fuel auxiliary machine assembly.
Is attached to the intake manifold 85 to form an assembly of the manifold and the fuel auxiliary equipment, and this is assembled to the main body of the engine E in the main assembly line, so that the number of assembly steps in the main assembly line is reduced. Can be enhanced.

As is clear from FIGS. 7 to 9, an air vent chamber 151 is formed in the upper part of the auxiliary fuel tank 89. The air vent chamber 151 has an upper cap 89 ₂
A pair of partitions 1 protruding from the ceiling surface of
52, and a baffle plate 153 joined to the lower end surfaces of the two partition walls 152. The baffle plate 153 has a through hole 154 that communicates the center of the air vent chamber 151 with the lower space. ing.

On the ceiling wall of the auxiliary fuel tank 89, the above air
A pair of first and second pairs each having one end opened to the vent chamber 151.
2 air vent hole 155₁, 155_TwoAnd these airbens
155₁, 155_TwoAir that connects the other end of the
A vent hole 156 is formed. At that time, the first and second
Air vent hole 155₁, 155_TwoIs one end of them
a ₁, A_TwoBut in the left-right direction of the auxiliary fuel tank 89
The center of the auxiliary fuel tank 89 in the front-rear direction as far as possible
(In the example shown, slightly behind the center)
151, and one of the first and second air vent holes
155₁, 155_TwoThe other end b of₁, B_TwoThe other airben
155_Two, 155₁One end of_Two, A₁Same as left and right
Each is formed in a hook shape so as to be disposed on the side. So
At this time, the first and second air vent holes 155₁, 155_Two
And the merged air vent hole 156 are arranged on the same horizontal plane.
Top cap 89_TwoThick part 89_Twoa
They are to be rilled, and their openings are blind plugs 157
Closed. As described above, the first and second air vent holes are provided.
155₁, 155_TwoAnd the same air vent hole 156
By arranging on a horizontal plane, the upper cap 89_Twoof
Thick part 89_TwoThe thickness increase of a can be minimized
You.

_On the upper surface of the upper cap 892, a joint 121 connected to the merging air vent hole 156 is erected, and the joint 121 projects from the upper surface of one side of the flange 2a of the under cover 5. It is connected to the joint 122 via the air vent pipe 120. Fitting 122
Has its lower end open to the empty space 34.

As shown in FIGS. 3 and 14, in the middle of the air vent pipe 120, a condensing means 114 capable of condensing fuel vapor passing therethrough is provided. The condensing means 114 includes a cylindrical synthetic resin housing 115 integrally having an upper joint 116, a synthetic resin lower joint 117 joined to a lower end of the housing 115 by a caulking ring 119, and a housing 115. And a screen 118 having a fine mesh that divides the interior into two chambers, an inner fuel chamber 89 side of the divided air vent pipe 120, an upper fuel pipe 89, and an air vent pipe 120. Fitting 12 of pipe 120
The two sides are respectively connected. The screen 118 has a bag shape with an upper end closed, and an open lower end peripheral portion is sandwiched between the housing 115 and the lower joint 117. The housing 115 and the swaging ring 119 are covered with a protective cover 126 made of rubber.

In the auxiliary fuel tank 89, the stored fuel
According to the increase or decrease of the fuel, the through hole 1 of the baffle plate 153
54, air vent chamber 151, first and second air vent holes 1
55 ₁, 155_Two, Converging air vent hole 156 and air vent
Vacant space 34 through an air vent path comprising
And the inside of the auxiliary fuel tank 89
Always keep the pressure approximately at atmospheric pressure and keep the fuel
Can be supplied without hindrance. Also, the auxiliary fuel tank
Link 89 receives radiant heat from engine E,
Hot excess fuel from the fuel tank 95 returns to the auxiliary fuel tank 89
The fuel in the auxiliary fuel tank 89 is
When steam is generated, the fuel vapor passes through the air vent.
Up the path, especially the air vent pipe 120
Fuel vapor passes through the housing 115 of the condensing means 114
When touching, it touches screen 118 and condenses and liquefies
The fuel flows down to the auxiliary fuel tank 89 and cannot be liquefied.
What passed through the air vent pipe 120 and the joint 1
The air is discharged from the space 22 to the empty room 34. Thus, fuel vapor
Is prevented from being sucked into the engine E, and
Condition can be avoided and the fuel vapor
Can be reduced to the outside.

Further, since the joint 122 projects from the upper surface of the flange portion 2a of the mount case 2, the air vent pipe 120 can be easily attached to and detached from the joint 122 with the engine cover 4 opened. In addition, since the air vent pipe 120 does not hinder the attachment and detachment of the engine cover 4, maintenance is excellent.

Since the joint 122 has its outer end opened to the empty space 34 surrounded by the under cover 5, the under cover 5 receives the splash of the wave, and the splash enters the air vent pipe 120. The breathing action of the auxiliary fuel tank 89 by the air vent pipe 120 can be ensured while effectively preventing it.

When the auxiliary fuel tank 89 is greatly inclined in the front-rear direction due to pitching of the hull or tilting of the outboard motor, the fuel stored in the tank 89 is shifted to the front or rear of the tank 89. Therefore, the tank 8
The opening ends a ₁ , a _{2 of} the first and second air vent holes 155 ₁ , 155 ₂ arranged at the substantially central portion in the front-rear direction of the air vent chamber 151 do not sink below the liquid level of the stored fuel. Further, when the auxiliary fuel tank 89 is greatly inclined due to rolling of the hull, steering of the outboard motor O in a tilted state, or the like, the fuel stored in the tank 89 is removed.
Of the first and second air vents 155 ₁ and 155 ₂ , the open end a ₁ or a ₂ to the air vent chamber 151 sinks below the level of the stored fuel. The other open end a ₂ or a ₁ can continue to open in the upper space of the tank 89. Moreover, even if one end a ₁ or a ₂ of one air vent hole sinks below the stored fuel liquid level, the other end b ₁ or b ₂ of the air vent hole occupies a position above the stored fuel liquid level. The stored fuel does not invade until. Therefore,
Regardless of the inclination of the outboard motor O, the inside of the auxiliary fuel tank 89 always has at least one of the air vent holes 155 ₁ or 155 ₂ continuously opening to the upper space thereof, the confluent air vent hole 156 and the air vent Tube 120
It is possible to breathe through the like, can be discharged fuel vapor generated in the said tank 89, the rear opening 4 ₁ outside without flowing out the stored fuel. Moreover, since only one air vent pipe 120 is required to be connected to the auxiliary fuel tank 89, the number of parts is small and the structure can be simplified.

The first and second air vent holes 155 ₁ ,
155 open end a, b of ₂ to the air vent chamber 151, so covered by the baffle plate 153, also by waving of the surface of liquid fuel in the auxiliary fuel tank 89, the first and second air vent holes 155 ₁ of the fuel, Infiltration into 155 ₂ can be suppressed by the baffle plate 153.

As shown in FIG. 7 and FIG.
Cap 89_TwoThe fuel return pipe L_FiveIs connected
Connection 159 and the fuel return hole 160 connected thereto
Is provided. The fuel return hole 160 is provided in the air vent.
So that it opens to the front of the front partition 152 of the
While the baffle plate 153 is
It is formed so as to protrude long in front of the wall 152. did
The fuel return pipe L _FiveHigh temperature and high pressure surplus fuel passed through
The battery in the auxiliary fuel tank 89 through the fuel return hole 160.
Because it will be exhaled on the full plate 153,
Bubbles contained in the fuel are placed on the baffle plate 153.
And mix air bubbles into the fuel stored in the auxiliary fuel tank 89.
Entrance can be avoided as much as possible. In addition, the return fuel
Float valve to prevent falling to float 109
90 can be prevented from malfunctioning.

Next, a cooling system for the engine E and the auxiliary fuel tank 89 will be described with reference to FIGS. 3, 8, 10 and 15.

The engine E has a main water jacket 162 for cooling the cylinder block 6 and the cylinder head 8 and a sub water jacket 163 for cooling the lubricating oil gallery.
Is provided with a water jacket 180 for its cooling. The entrance of the main water jacket 162 is
4, the water intake 16 of the extension case 1
5 (see FIG. 1), and a water pump 166 driven by the drive shaft 17 is interposed in the main water passage 164. The outlet of the main water jacket 162 is connected to a first drainage channel 168 ₁ via a thermo valve 167, and the downstream end thereof is opened into the extension case 1.
The inlet of the main water jacket 162 and the first drainage channel 1
68 ₁ and is connected via a bypass water passage 170 having a first relief valve 169 _1, the first relief valve 169 ₁ is adapted to open when the pressure of the water passage 164 is equal to or greater than a prescribed value.

In the middle of the main channel 164, a first branch channel 171 is provided.
Is connected to the inlet of the auxiliary water jacket 163, and the outlet thereof is connected to the extension case 1.
The second drainage channel 168 ₂ opening the downstream end is connected to the inside,
The second drainage channel 168 ₂ has a sub water jacket 1
63 water pressure of the second relief valve 169 ₂ is provided which opens when equal to or greater than a prescribed value. This second relief valve 169 ₂
Opening pressure of is set first relief valve 169 ₁ lower.

A second branch water passage 172 is connected to the first branch water passage 171, which is connected to an inlet pipe 175 of the water jacket 180 of the auxiliary fuel tank 89, and an orifice 174 is provided in the middle thereof. Outlet pipe 176 of the water jacket 180 is connected to _two said second drainage channel 168. Further, a water detection passage 177 connected to a water detection hole 178 opened on the outer surface of the extension case 3 upstream of the orifice 174 is connected to the second branch water passage 172. The water detection passage 177 is located below the water jacket 180 of the auxiliary fuel tank 89 even when the outboard motor O is tilted up.

When the engine E is operating, the drive shaft 17
The water pump 166 driven by the
The cooling water pumped from 5 is supplied to the main channel 164, the first branch channel 171, the second branch channel 172, and the third branch channel 173. The cooling water supplied to the water channel 164, at the time of warming up of the engine E thermo valve 167 is closed, the warming-up of the engine E flows through the bypass water passage 170 pushes and opens the first relief valve 169 ₁ Facilitate. After the warm-up, when the thermo valve 167 opens, the first relief valve 16
9 ₁ is closed, now the cooling water flows through the main water jacket 162 can cool the engine E.

The cooling water supplied to the first branch water passage 171 is
The water flow is always the first, regardless of whether the engine E is cold or warm.
Relief valve 169_TwoVice water jacket while pushing open
163 to cool the oil gallery for lubrication
You. In addition, the first relief valve 169 _TwoValve opening pressure is relatively low
Since the setting has been made, the secondary
Even if the water pressure of the water jacket 163 drops, the first
Leaf valve 169_TwoCan keep open.

The second and third branch waterways 172, 173
Is always flowing through the water jacket 180 of the auxiliary fuel tank 89 to cool the tank 89 irrespective of whether the engine E is cold or warm, and the remainder passes through the water passage 177. The water is discharged from the test hole 178.

The detour water channel 170 and each water jacket 1
The cooling water having passed through 62, 163, 180 is discharged into the extension case 1 through the first drain passage 168 ₁ or the second drain passage 168 _2, and into the water from the boss hollow portion of the propeller 20 together with the exhaust gas of the engine E. Is discharged.

As shown in FIGS. 8 and 10, the water jacket 180 comprises a side wall 89 ₁ a of the tank body 89 ₁ of the auxiliary fuel tank 89 adjacent to the engine E and a side cap 181 joined thereto. Is defined between The water jacket 180 is formed to extend long in the front-rear direction.
5. An outlet pipe 176 is attached to the upper part, and the inlet pipe 1
75, the third branch channel 173 is connected to the outlet pipe 17.
6 is connected to the second drainage channel 168 ₂ . In addition, in the water jacket 180, the inlet pipe 175 and the outlet pipe 1 are provided.
A water flow guide wall 184 extending horizontally in the front-rear direction is disposed at an intermediate portion of the horizontal direction 76. The water flow guide wall 184 is formed of a pair of right and left ribs 184a integrally formed on the opposing surfaces of the side wall 89 ₁ a and the side cap 181. , 184b, a small gap 185 is provided between the water jacket 180 and the front end wall, and a large gap 186 is provided between the water jacket 180 and the rear end wall.

Therefore, during the operation of the engine E, most of the cooling water flowing from the third branch water channel 173 through the inlet pipe 175 into the water jacket 180 largely goes around the water flow guide wall 184 so as to pass through the large gap 186. That is, it is possible to efficiently cool the auxiliary fuel tank 89 by flowing the entire water jacket 180 without stagnation, thereby effectively cooling the fuel in the tank 89 and minimizing the generation of fuel vapor. Can be. Cooling water passing through the water jacket 180 flows out from the outlet pipe 176 to the second drain pipe 168 _2.

When the operation of the engine E is stopped, the operation of the water pump 166 is also stopped, so that the main water jacket 162 and the sub water jacket 16 of the engine E are stopped.
The cooling water in 3 can mainly flow down the main channel 164 and flow out of the water intake 165 to the outside. The cooling water in the water jacket 180 of the auxiliary fuel tank 89 is supplied to the inlet pipe 175, the third branch channel 173, and the water detection channel 17.
7 can flow down to the outside through the test hole 178.

In this case, in particular, the inlet pipe 175 is formed at the lower part of the front end wall of the water jacket 180 of the auxiliary fuel tank 89.
Is provided, even if the outboard motor O is in the tilted-up state, the front end wall of the water jacket 180 comes below the rear end wall, and the inlet pipe 175 is located at the lowermost position. In addition, the water above the water flow guide wall 184 can also move to the inlet pipe 175 through the small gap 185, and the water detection passage 177 is provided below the inlet pipe 175.
The cooling water in the water jacket 180 is
From 75, it can flow out to the water detection channel 177. By draining water from the water jackets 162, 163, and 180 in this manner, it is possible to prevent rusting of the inner surfaces of the water jackets 162, 163, and 180 due to residual water and damage to various parts due to freezing of the residual water.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof. For example, the joint 122 can be provided at the bottom of the extension case 3 facing the empty space 34.

[0065]

As described above, according to the first aspect of the present invention, the auxiliary fuel for receiving the surplus fuel recirculated from the fuel injection valve side of the engine and separating the fuel vapor from the stored fuel in the engine room. A tank is provided, the inner end of an air vent pipe communicating with the upper space inside the auxiliary fuel tank is connected to the auxiliary fuel tank, and a joint formed in the lower case and facing the engine room and projecting outside the extension case protrudes. Since the outer end of the air vent pipe is connected to this joint, the fuel vapor generated in the auxiliary fuel tank can be discharged out of the engine room through the air vent pipe and the joint, so that the fuel vapor is transmitted to the engine. Deterioration of the exhaust properties due to the inhalation can be avoided. Moreover, the air vent pipe can be easily attached to and detached from the joint while the engine cover is open, and the air vent pipe does not hinder the attachment and detachment of the engine.

According to a second feature of the present invention, a cover member for covering at least a part of the lower case is attached to the lower case, and the joint is opened in an empty space defined between the cover member and the lower case. Therefore, it is possible to secure the breathing action of the auxiliary fuel tank by the air vent pipe while preventing the splash of the waves from entering the air vent pipe using the cover member of the lower cover.

Further, according to the third feature of the present invention, since the condensing means for condensing the fuel vapor is provided in the middle of the air vent pipe, the fuel vapor flowing from the auxiliary fuel tank to the air vent is captured and condensed by the condensing means. Then, the fuel vapor is returned to the auxiliary fuel tank, and discharge of fuel vapor to the outside can be reduced as much as possible.

[Brief description of the drawings]

FIG. 1 is an overall side view of an outboard motor according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a view in the direction of arrows in FIG. 2;

FIG. 4 is a view in the direction of arrows in FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 3;

FIG. 6 is an enlarged sectional view of a main part of FIG. 3;

FIG. 7 is a view taken in the direction of arrow 7 in FIG. 6;

8 is a view taken in the direction of arrow 8 in FIG. 7;

9 is a sectional view taken along line 9-9 in FIG. 7;

FIG. 10 is a sectional view taken along line 10-10 of FIG. 7;

11 is a sectional view taken along line 11-11 of FIG. 7;

FIG. 12 is a sectional view taken along line 12-12 of FIG. 7;

FIG. 13 is an enlarged sectional view taken along line 13-13 of FIG. 3;

FIG. 14 is an enlarged sectional view taken along line 14-14 of FIG. 3;

FIG. 15 is a cooling water circuit diagram.

[Explanation of symbols]

 1 ... Extension case 2 ... Engine support (mount case) 2a ... Flange 3 ... Extension case 4 ... Engine cover 5 ... Undercover (cover member) 17 ··· Drive shaft 21 ··· Propeller shaft 34 ··· Vacancy 36 ··· Engine room 89 ··· Auxiliary fuel tank 94 ··· Fuel injection valve 114 ... condensing means 120 ... air vent pipe 122 ... joint C ... bottom cover E ... engine O ... outboard motor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI F02M 37/20 F02M 37/20 U 55/00 55/00 Z (72) Inventor Makoto Miyake 1-4-4 Chuo, Wako-shi, Saitama No. 1 Inside Honda R & D Co., Ltd.

Claims (3)

[Claims] An engine support (2) coupled to an upper end of an extension case (1) for accommodating a drive shaft (17) for driving a propeller shaft (21) has a drive shaft (1).
7) An engine (E) for driving the engine (E) is mounted, and an engine room (36) accommodating the engine (E) is provided in a lower case (C) including an engine support (2) and a lower case (C). Removable engine cover (4)
In the outboard motor configured as described above, the engine room (36) receives surplus fuel recirculated from the fuel injection valve (94) side of the engine (E), and
Auxiliary fuel tank (8) for separating fuel vapor from stored fuel
The auxiliary fuel tank (89) is connected to the inner end of an air vent pipe (120) communicating with the upper space inside the auxiliary fuel tank (89). The auxiliary fuel tank (89) is formed in a lower case (C) to form an engine room (36). And extension case (1)
A fuel vapor separation device for an outboard motor, characterized in that a joint (122) that opens to the outside is protruded, and an outer end of an air vent pipe (120) is connected to the joint (122). 2. The lower case (C) according to claim 1, wherein a cover member (5) covering at least a part of the lower case (C) is attached to the lower case (C), and a lower member (C) is defined between the cover member (5) and the lower case (C). The joint (1)
22. A fuel vapor separation device for an outboard motor, characterized in that the opening of (22) is opened. 3. The fuel vapor in an outboard motor according to claim 1, wherein a condensing means (114) for condensing the fuel vapor is provided in the air vent pipe (120). Separation device.