JPH1047110A - Installing structure of oxygen concentration sensor for outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out air-fuel ratio control with high accuracy so as to improve reliability of an engine by arranging an oxygen concentration sensor facing to the exhaust passage of a four cycle engine for an outboard engine. SOLUTION: An exhaust passage 18 of each cylinder is formed on a cylinder head 8 formed each intake passage 35 on a left side part at an intervals in a vertical direction, which is communicated with mutually in an exhaust collector passage 190 formed integratedly with a cylinder block 31 on the right side of a cylinder in a vertical direction. The lower end of passage 190 is connected to the exhaust passage of an exhaust guide. An oxygen concentration sensor 191 is arranged facing to an exhaust passage 18 positioned most upward of the exhaust passage 18 from each cylinder or positioned most downward it. It is thus possible to control an air-fuel ratio with high accuracy, and it is also possible to improve reliability of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an oxygen concentration sensor of an outboard motor, and more particularly to a mounting structure of an oxygen concentration sensor of an outboard motor used for controlling an air-fuel ratio of a four-stroke engine for an outboard motor. It is.

[0002]

2. Description of the Related Art In a general vehicle equipped with a four-cycle engine, air-fuel ratio control is performed to improve power, improve fuel efficiency, purify exhaust gas, and the like. In the air-fuel ratio control, for example, the concentration of oxygen contained in the exhaust gas of the engine is detected by an oxygen concentration sensor, and the detected oxygen concentration is fed back to a control device, and the fuel injection amount and the like are controlled based on the detected oxygen concentration. This is done by:

[0003] In an outboard motor such as a motorboat or a small boat, a two-stroke engine having a simple structure without a valve operating mechanism, miniaturization, and a large output with respect to the displacement is used. In this two-stroke engine outboard motor, the oxygen concentration in the exhaust gas must be detected without the effects of blow-by of fresh air, etc., so that the sensor mounting position is restricted and the structure becomes complicated, and the influence between cylinders is also affected. However, the detection reliability was not sufficient. That is, in order to accurately perform the air-fuel ratio feedback control by the oxygen concentration sensor, a device for reducing the influence of fresh air is necessary. For example, a concave portion is provided in the cylinder wall and the oxygen concentration is detected in the concave portion. The method was used.

[0004]

However, practical use of a four-stroke engine has been desired also for an outboard motor in terms of controllability, economy, and environmental protection. In this case, the reliability of the outboard motor is particularly required due to the special circumstances of operation on water. Therefore, it is desirable to perform high-precision air-fuel ratio control using an oxygen concentration sensor to improve engine reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an attachment structure of an oxygen concentration sensor for controlling an air-fuel ratio in an outboard motor equipped with a four-cycle engine.

[0006]

According to the present invention, there is provided an outboard motor having an oxygen concentration sensor disposed in an exhaust passage of a four-stroke engine for an outboard motor. Provided is a mounting structure for an oxygen concentration sensor.

According to the above arrangement, in the outboard motor of the four-cycle engine, the oxygen concentration in the exhaust gas flowing through the exhaust passage is detected by the oxygen concentration sensor, so that a high-precision air-fuel ratio is obtained based on the detected oxygen concentration. Control enables optimal air-fuel ratio control in response to all operating conditions on the water, while effectively exhibiting engine output.
Its reliability can be improved. Also, in the case of a four-stroke engine, there is no fresh air blow-through unlike the two-stroke engine, so there is almost no restriction on the mounting position on the exhaust pipe.
Accurate oxygen concentration can be detected without using a special structure, and there is little influence between cylinders, and detection reliability is high.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment,
The engine is composed of a plurality of cylinder engines arranged vertically, an exhaust passage from each cylinder is communicated with a vertical exhaust collecting passage, and the oxygen concentration sensor is provided facing the exhaust passage of one of the cylinders. It is characterized by. In another preferred embodiment, the oxygen concentration sensor is provided so as to face the uppermost exhaust passage.

In another preferred embodiment, the oxygen concentration sensor is provided so as to face the lowermost exhaust passage.

In still another preferred embodiment, the engine is constituted by a plurality of vertically arranged cylinder engines, and the oxygen concentration sensor faces a vertical exhaust collecting passage in which exhaust passages from the respective cylinders are gathered. Is provided.

[0011] In another preferred embodiment, the oxygen concentration sensor is provided so as to face a connecting portion of the exhaust passage located at the uppermost position of the exhaust collecting passage. In another preferred embodiment, the oxygen concentration sensor is provided so as to face a connecting portion of the exhaust passage located at the lowest position of the exhaust collecting passage.

[0012]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of an outboard motor equipped with a four-cycle, four-cylinder, vertical L-type engine to which the mounting structure of the oxygen concentration sensor according to the present invention is applied. Also,
FIG. 2 is a horizontal sectional view of a main part of an engine housed in a cowling of the outboard motor of FIG. The outboard motor 1 has components housed in a housing constituted by a cowling 5, an upper case 6a and a lower case 6b. The cowling 5 includes a top cowl 5a, a bottom cowl 5b, and an air duct cover 5c. The upper case 6a has its upper part covered with an apron. A propeller 17 is mounted on the lower case 6b. The outboard motor 1 is attached to a rear tail plate of a hull via a mounting bracket 2. The outboard motor 1 is rotatable around the tilt shaft 2a and the swivel shaft 4, thereby enabling steering.

The engine 7 of this example is a four-cycle, four-cylinder L-type fuel injection EFI engine in which the cylinders are arranged in the vertical direction. The engine 7 is fixed to the upper surface of an exhaust guide 20 installed between the bottom cowl 5b and the upper case 6a, and is housed in the cowling 5 above the outboard motor with the upper surface side covered by a cover member. I have.

The main body of the engine 7 comprises a head cover, a cylinder head 8, a cylinder block 31 forming a part of the cylinder body and the crank chamber 32, and a crankcase 74 integrally formed along the longitudinal direction of the hull. It is formed by connecting. In this case, the side of the crankcase 74 is the front part F, and the side of the head cover is the rear part R.
It is arranged so that it becomes.

The cylinder head 8 has a cylinder
The exhaust valves 36 and 39 are mounted. Each valve 36, 3
The camshafts 37a and 40a for driving the shaft 9 are driven by a cam cap and a bearing portion of the cylinder head 8 in a cam chamber defined by the head cover and the cylinder head 8 so that the rotation axis direction is the vertical direction. Supported. A cam pulley is fixed to an upper end of each cam shaft at a portion (not shown) covered by the cover member.

In a crank chamber 32 defined by a front part of the cylinder block 31 and a crank case 74, a crank shaft 52 common to the cylinders is arranged such that the direction of the rotation axis is vertical. This crankshaft 52
Is connected to a piston 34 via a connecting rod 33 of each cylinder. The flywheel 12 is fixed to an upper end of the crankshaft 52, and a timing pulley is fixed below the flywheel 12. A timing belt for transmitting the rotation of the crankshaft 52 to the camshafts 37a and 40a of the intake and exhaust valves 36 and 39 is stretched over the timing pulley and each of the cam pulleys. Crankshaft 52
A drive shaft 14 (FIG. 1) is connected to the lower end of the drive shaft, and drives the propeller 17 through a clutch, a reduction gear, or the like (not shown). On the front left side of the engine 7, a surge tank 10 serving as an air introduction portion of an intake passage for sending air into the combustion chamber of each cylinder of the engine 7 is provided. At the upper end of the surge tank 10, a throttle body 62 is provided.
Is provided, and an intake port 62c is opened on the upper surface thereof. A throttle section 62a for opening and closing a throttle valve (not shown) for controlling the amount of intake air is provided near the intake port 62c. Throttle body 6
Numeral 2 communicates via an air duct 9 with an air intake covered by an air duct cover 5c.

The opening and closing of the throttle valve in the throttle section 62a is performed via a throttle cable 62b by operating a throttle remote control cable 62d extending from a boat seat on the hull side.

The cylinder head 8 of the engine 7
On the left side, are formed intake passages 35 of the respective cylinders at intervals in the vertical direction. The intake passages 11 extend from the surge tank 10 toward the intake passages 35 for each cylinder. Each of the intake passages 11
The upstream intake pipe located on the front side and the downstream intake pipe located on the rear side are formed by being connected via an insulator.

When viewed from above, each intake passage 11 has an upstream intake pipe connected to the surge tank 10 gently bent substantially in parallel with the wall surface of the crankcase 74, and then, at the side of the engine body. It extends substantially parallel to the axis of the engine cylinder. Further, the downstream intake pipe 42 connected to the intake passage 35 is bent at a substantially right angle from the rear end of the upstream intake pipe 41 and connected to the inlet of the intake passage 35.

In the cylinder head 8 in which the intake passages 35 are formed on the left side, exhaust passages 18 of the respective cylinders are formed on the right side thereof at intervals in the vertical direction. The exhaust passages 18 of the respective cylinders are vertically communicated with each other within an exhaust collecting passage 190 formed integrally with the cylinder block 31 on the right side of the cylinder. This exhaust collecting passage 190
Has a lower end connected to the exhaust passage 4 of the exhaust guide 20 (FIG. 1) in order to discharge exhaust gas below the engine body.
3 is connected. The exhaust gas is exhausted into the main exhaust chamber 21 and further discharged into the water together with cooling water through an exhaust port around the propeller shaft.

A second surge tank 195 is provided between the engine body and the upstream-side intake pipe 41, and a second surge tank 195 is provided.
Communicate with An intake control valve 196 is provided in the communication pipe, and controls intake air from the second surge tank 195 according to an operation state.

Further, an injector 38 for injecting fuel into the intake air is provided in the intake passage 11 of each cylinder so that the injector 38 injects fuel toward the intake valve 36 facing the inside of the downstream intake pipe 42. Installed in.

Further, in order to supply fuel to each injector 38, a fuel pump 86 driven by being pushed by a cam nose of a cam shaft 37a while being fixed to a head cover.
Is installed.

The fuel path will be described with reference to FIG. A vapor separator tank 48 provided with a high-pressure pump 47 is provided outside the upstream intake pipe 41, and a fuel filter 4 is provided below the vapor separator tank 48.
9 are installed. Hull side fuel tank (not shown)
The fuel stored in the fuel pump 86 is driven by the rotation of a camshaft 37a (see FIG. 2) on the intake side.
The fuel is introduced through a fuel supply pipe 251. This fuel is supplied from the fuel supply pipe 251 to the fuel filter 49 and the fuel supply pipe 2.
After passing through 52, the fuel is sucked and discharged by the fuel pump 86, and is fed into the vapor separator tank 48 via the fuel supply pipe 253.

The fuel fed into and accumulated in the vapor separator tank 48 is supplied to the injector 38 of each cylinder through the high-pressure fuel supply pipe 254 by the high-pressure pump 47 attached to this tank. The fuel rail 255 is supplied from its lower end at high pressure.

The high-pressure fuel supplied to the fuel rail passes through the injectors 38 in order, and in each injector 38, a solenoid is operated by a current from a control device described later in accordance with the valve timing of each cylinder. When the nozzle is opened by
The fuel is injected from the injector 38.

Excess fuel that has passed through each injector 38 by the fuel rail passes through a pressure regulator 257 via a fuel return pipe 256 connected to the upper end of the fuel rail 255, and passes through a vapor separator tank 48.
And is sent again to each injector 38 by the high-pressure pump 47.

Each of the injectors 38
This is a so-called top feed type injector in which fuel is supplied from the end opposite to the nozzle, and a fuel rail for sequentially supplying fuel to each injector 38 connects the rear end of each injector 38 at intervals. Are arranged as follows.

In this embodiment, the exhaust passage 35 from each cylinder is provided.
The oxygen concentration sensor 191 is provided so as to face the uppermost exhaust passage 18 or the lowermost exhaust passage 18 (in FIG. 1, the sensors 191 are illustrated at two upper and lower positions. Or just fine). In this case, if the oxygen concentration sensor 191 is provided in the exhaust passage 18 of the uppermost cylinder, it is less susceptible to salt damage, which is advantageous in terms of durability. Further, when the exhaust gas is provided at a position as far as possible from the exhaust port, the exhaust gas is uniformly mixed, and a stable and highly reliable output can be obtained.

The oxygen concentration sensor 191 detects the oxygen concentration in the exhaust gas and checks the combustion state in the cylinder. The configuration of the oxygen concentration sensor 191 itself is publicly known, and the output changes stepwise at the stoichiometric air-fuel ratio. As a result, rich and lean air-fuel ratios are detected,
When a large amount of oxygen is detected, feedback control is performed by a control device described later to increase fuel, and when a small amount of oxygen is detected, the fuel is reduced by a control device described later to optimize the air-fuel ratio. Try to get closer. As a result, an optimum combustion state is obtained, and power is increased and exhaust gas is purified. Note that the oxygen concentration sensor 191 may be provided in the exhaust collecting passage 190 as in the embodiment described later.
Alternatively, as shown in FIG.
May be provided facing the exhaust passage 43 of the lower exhaust guide 20.

FIG. 3 is an explanatory top view of an embodiment of an outboard motor equipped with a four-cycle, five-cylinder, vertical L-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.
Also in this example, the oxygen concentration sensor 191 is provided in the uppermost exhaust passage 18 or the lowermost exhaust passage 18 among the five exhaust passages 18 of the five cylinders, similarly to the outboard motor of FIGS. It is provided to face. The structure of each part of the engine is the same as that of the aforementioned four-cylinder engine.

FIG. 4 is a horizontal sectional view of an essential part of an embodiment of an outboard motor equipped with a four-cycle six-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.
FIG. 5 is a rear view of the engine portion. The engine is provided with two banks 30a, 30b vertically arranged in a V-shape on each of the left and right sides of the crankshaft 52 obliquely rearward.
A cylinder block is joined to the cylinder head of each cylinder of each bank, and each cylinder block is fixed to the crankcase 74. This common crankshaft 5
The crankcase 74 accommodating 2 is assembled and fixed to a V-shaped cylinder block by bolts 75 provided at appropriate plural places.

Each cylinder block is formed toward the rear of the common crank chamber 32, and a piston 34 slides inside. Each piston 34 and the crankshaft 52 are connected via the connecting rod 33 at a predetermined crank phase difference angle.

Each of the left and right banks 30a and 30b is provided with one common intake surge tank 10 and an intake passage 11 branched therefrom, and communicates with the intake passage 35 of each cylinder. The injector 38 is mounted in the middle of the intake passage 35 of each cylinder so as to face the intake passage 35, and an intake valve 36 is attached to an intake port at the end of the intake passage. Intake valve 36
The cam (not shown) mounted on the camshaft 37a, which rotates in synchronization with the crankshaft 52, presses the valve lifter at the upper end of the valve shaft against the spring, thereby sliding along the valve guide, It opens and closes in synchronization with the rotation of the crankshaft 52.

An exhaust passage 1 is provided in the cylinder head of each cylinder.
8 is formed, and an exhaust valve 39 is attached to an exhaust port at the end. Each exhaust valve 39 is opened and closed at a predetermined timing by a cam mounted on a cam shaft 40a, similarly to the intake valve 36. A hole for mounting a spark plug is formed in the center of each cylinder head. Three exhaust passages 1 for each bank
8 is formed inside the left and right banks 30a, 30b and obliquely rearward in the cylinder head as shown in the figure.
An exhaust collecting passage 19 in which the three exhaust passages 18 of each bank are collected has a configuration in which exhaust gas of all three cylinders of each bank is collected at the lower end. The collected exhaust communicates with the exhaust passage 43 of the exhaust guide 20 for each bank.

As described above, one common intake surge tank 10 is provided for each of the left and right banks, and a throttle body 62 for adjusting the intake air amount is provided at the upper center of the surge tank 10.

From the surge tank 10, three left and right banks of intake passages 11 are provided in a branched manner, and are respectively connected to intake passages 35 of three cylinders vertically arranged in each bank.

In this embodiment, the connecting portion of the exhaust passage 18 located at the top of the four exhaust collecting passages 19 of the left and right banks and the connecting portion of the exhaust passage 18 located at the lowest position are shown in FIG. The oxygen concentration sensor 191 is provided facing any one of the four locations. Exhaust passage 1
The oxygen concentration sensor 191 provided at the lowermost position of No. 9 can detect the oxygen concentration in the exhaust gas collected from each cylinder, and can stably and accurately detect the oxygen concentration without variation. Further, the oxygen concentration sensor 191 located at the uppermost position of the exhaust collecting passage 19 is far from the water surface, and thus is hardly affected by salt damage.

FIG. 6 is a rear view of an engine portion of an example of an embodiment of an outboard motor equipped with a four-cycle eight-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied. Also in this example, as in the outboard motors of FIGS. 4 and 5, the connection between the uppermost exhaust passage 18 and the lowermost exhaust passage 18 of the respective exhaust collecting passages 19 in the left and right banks. The oxygen concentration sensor 191 is provided facing any one of the four locations.

FIG. 7 is a horizontal sectional view of a main portion of another embodiment of an outboard motor equipped with a four-cycle six-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.
FIG. 8 is a rear view of the engine portion. In this example,
As shown in the figure, the six exhaust passages 18 of each bank are formed inside the left and right banks 30a and 30b and in the cylinder head diagonally forward. The six exhaust passages 18 of both banks gather in one exhaust collecting passage 19 inside between the two banks. That is, in the exhaust collecting passage 19, the exhaust of all the six cylinders # 1 to # 6 of both banks is collected at the lower end.
The collected exhaust communicates with the exhaust passage 43 (FIG. 8) of the exhaust guide 20. In this example, two of the left and right exhaust passages 18 located at the top of the exhaust passages from the respective cylinders of the left and right banks, the uppermost position of the exhaust collective passage 19, and the lowermost position of the exhaust collective passage. The oxygen concentration sensor 191 is provided facing any one of the four locations.

FIG. 9 is a rear view of an engine part of still another embodiment of an outboard motor equipped with a four-cycle eight-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor according to the present invention is applied. Also in this example, similarly to the outboard motors of FIGS. 7 and 8, the uppermost two exhaust passages 18 of the exhaust passages from the cylinders of the left and right banks and the uppermost one of the exhaust collective passages 19 are provided. Position and the oxygen concentration sensor 19 at one of the four lowermost positions of the exhaust collecting passage.
1 is provided.

FIG. 10 is a block diagram of a control system of the fuel injection device of the outboard motor shown in FIGS. 7 and 8 to which the oxygen concentration sensor of the present invention is applied. In this figure, an oxygen concentration sensor 191 is provided in the exhaust passage 18 of the cylinder # 1 in the right bank. Detection signals from various sensors indicating the driving state of the engine, the state of the outboard motor and the state of the boat are input to the control device 568. That is, as sensors, a crank angle sensor 590 for detecting a rotation angle (rotation speed) of a crankshaft, an in-cylinder pressure sensor 592 for detecting a pressure in each cylinder, an intake temperature sensor 593 for detecting a temperature in an intake passage, a cylinder body An engine temperature sensor 594 for detecting the temperature of the engine, a back pressure sensor 595 for detecting the back pressure of each cylinder, a throttle opening sensor 596 for detecting the opening of the throttle valve, a cooling water temperature sensor 597 for detecting the temperature of the cooling water, An engine vibration sensor 598 for detecting an engine frequency, an engine mount height detection sensor 599 for detecting an engine mount height, a neutral sensor 600 for detecting a neutral state of a power transmission device of an outboard motor, and detecting a boat speed. Ship speed sensor 60
2. A boat attitude sensor 603 for detecting the attitude of the boat, an atmospheric pressure sensor 604 for detecting the atmospheric pressure are provided, and an oxygen concentration sensor 19 is provided in the exhaust passage 18 of the cylinder # 1 in the right bank.
1 is provided. The control device performs arithmetic processing on the detection signals of these various sensors, and transmits the control signals to the respective drive units of the ignition plug, the injector 538, and the throttle valve.

The fuel is sent from the inboard tank 541 to the sub-tank 542 by the low-pressure fuel pump 548 via the filter 551, and is sent to the injector 538 by the high-pressure fuel pump 552. The return fuel from the injector 538 is supplied to the sub tank 5 via the pressure regulator 559.
It is returned to 42.

According to the above-described control system, when the air-fuel ratio is changed from the lean side to the rich side by a sensor such as the oxygen concentration sensor 191, the fuel injection amount from the injector 538 is reduced. Control, the air-fuel ratio gradually changes to lean side by this control,
When it is detected that the air-fuel ratio has changed from the rich side to the lean side, the stoichiometric air-fuel ratio (excess air ratio λ = 1) is controlled on average by controlling the fuel injection amount from the injector 538 to increase. The fuel injection amount can be controlled such that Further, the injection timing and the ignition timing can be controlled at the optimum air-fuel ratio according to the operating state.

The mounting position of the oxygen concentration sensor 191 is not limited to the position in the above embodiment, but may be provided in the exhaust passage at the upper and lower middle part or at the intermediate position of the exhaust collecting passage.
In addition, it can be appropriately changed according to the shape and arrangement of the exhaust passage.

[0046]

As described above, according to the present invention, since the oxygen concentration sensor is provided in the exhaust passage of the outboard motor of the four-cycle engine, the High-precision air-fuel ratio control can be performed using the concentration sensor, and the output performance of the engine is improved to achieve stable and reliable operation. Thereby, the reliability of the outboard motor equipped with the four-cycle engine can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of an example of an embodiment of an outboard motor equipped with a four-cycle four-cylinder vertical L-type engine to which an attachment structure of an oxygen concentration sensor of the present invention is applied.

FIG. 2 is a horizontal sectional view of a main part of an engine housed in a cowling of the outboard motor of FIG.

FIG. 3 is an explanatory top view of an example of an embodiment of an outboard motor equipped with a four-cycle, five-cylinder vertical L-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.

FIG. 4 is a horizontal cross-sectional view of a main part of an example of an embodiment of an outboard motor equipped with a four-cycle six-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.

FIG. 5 is a rear view of an engine portion of the outboard motor of FIG. 4;

FIG. 6 is a rear view of an engine portion of an embodiment of an outboard motor equipped with a four-cycle eight-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.

FIG. 7 is a horizontal cross-sectional view of a main part of another embodiment of an outboard motor equipped with a four-cycle eight-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.

FIG. 8 is a rear view of an engine portion of the outboard motor of FIG. 7;

FIG. 9 is a rear view of an engine part of still another embodiment of an outboard motor equipped with a four-cycle eight-cylinder vertical V-type engine to which the mounting structure of the oxygen concentration sensor of the present invention is applied.

FIG. 10 to which the oxygen concentration sensor of the present invention is applied.
It is a block diagram of the control system of the fuel injection device of outboard motors of No.-8.

11 is a side view showing a fuel system of the outboard motor of FIG.

[Explanation of symbols]

1: Outboard motor, 2: Mounting bracket, 5: Cowling, 5
a: Top cowl, 5b: Bottom cowl, 5c: Air duct cover, 6a: Upper case, 6b: Lower case, 7: Engine, 8: Cylinder head, 9: Air duct, 10: Surge tank, 11: Intake passage, 12: Flywheel, 14: drive shaft, 17: propeller, 18: exhaust passage, 19, 190: exhaust passage, 20: exhaust guide, 30a: right bank, 30b: left bank, 3
1: cylinder block, 32: crank chamber, 33: connecting rod, 34: piston, 35: intake passage, 36: intake valve, 37a: camshaft, 38,538: injector, 39: exhaust valve, 40a: camshaft, 43: exhaust passage, 52: crankshaft, 62a: throttle section, 62
c: intake port, 74: crankcase, 86: fuel pump, 191: oxygen concentration sensor, 541: inboard tank, 5
42: Sub tank, 548: Low pressure fuel tank, 551:
Filter, 552: High-pressure fuel pump, 559: Pressure regulator, 568: Control device, 590: Crank angle sensor, 593: Intake temperature sensor, 594: Engine temperature sensor, 595: Back pressure sensor, 596: Throttle opening sensor, 597 : Cooling water temperature sensor, 598: engine vibration sensor, 599: engine mount detection sensor, 60
0: neutral sensor, 602: ship speed sensor, 60
3: Ship attitude sensor, 604: Atmospheric pressure sensor

Claims (7)

[Claims] 1. An outboard motor oxygen concentration sensor mounting structure wherein an oxygen concentration sensor is provided in an exhaust passage of a four-stroke engine for an outboard motor. 2. The engine according to claim 1, wherein the engine comprises a plurality of cylinder engines arranged vertically, an exhaust passage from each cylinder communicates with a vertical exhaust collecting passage, and the oxygen concentration sensor is connected to an exhaust passage of one of the cylinders. 2. The mounting structure for an oxygen concentration sensor for an outboard motor according to claim 1, wherein: 3. The mounting structure of an outboard motor according to claim 2, wherein the oxygen concentration sensor is provided so as to face the uppermost exhaust passage. 4. The mounting structure of an outboard motor according to claim 2, wherein the oxygen concentration sensor is provided so as to face the lowermost exhaust passage. 5. The engine according to claim 1, wherein the engine comprises a plurality of vertically arranged cylinder engines, and the oxygen concentration sensor faces a vertical exhaust collecting passage where exhaust passages from respective cylinders are gathered. An outboard motor oxygen concentration sensor mounting structure according to claim 1. 6. The oxygen concentration sensor for an outboard motor according to claim 5, wherein the oxygen concentration sensor is provided so as to face a connecting portion of the exhaust passage located at the uppermost position of the exhaust collecting passage. Mounting structure. 7. The oxygen concentration sensor for an outboard motor according to claim 5, wherein the oxygen concentration sensor is provided so as to face a connecting portion of the exhaust passage located at a lowermost position of the exhaust collecting passage. Mounting structure.