JP4221037B2 - O2 sensor mounting structure for small vessels - Google Patents

Description

The present invention relates to an O ₂ sensor mounting structure in a small vessel.

  When a fuel-injection engine is adopted as an engine mounted on a small boat such as a watercraft, it is necessary to keep the air-fuel ratio (hereinafter referred to as A / F) of the air-fuel mixture optimally according to the operating state of the engine. It is desirable from the viewpoint of improvement of performance, fuel efficiency and exhaust gas characteristics.

By the way, as a method for detecting the A / F of the air-fuel mixture, a method for obtaining A / F based on the O ₂ concentration in the air-fuel mixture detected by the O ₂ sensor provided in the intake passage can be considered. In this method, the A / F of the air-fuel mixture supplied to the combustion chamber is accurately detected because the unvaporized fuel in the air-fuel mixture flowing along the wall surface of the passage is vaporized during or after entering the combustion chamber. I can't.

Therefore, for example, an O ₂ sensor is arranged in the exhaust pipe, and the A / F of the air-fuel mixture is calculated based on the O ₂ concentration in the exhaust gas detected by the O ₂ sensor, and based on the calculated A / F. Thus, an air-fuel ratio control method for controlling the fuel injection amount (fuel injection time) according to the operating state of the engine so that the actual A / F becomes a desired value has been conventionally used.

However, in a small vessel with the downstream end of the exhaust pipe connected to the engine open to the water, if this falls over and the water enters the exhaust pipe, this water is not quickly discharged and placed in the exhaust pipe. As a result, the detection system of the O ₂ sensor and the durability of the sensor are reduced.

The present invention was made in view of the above problems, treatment is to provide the O ₂ sensor mounting structure in a small boat which can ensure high detection accuracy and durability to the O ₂ sensor and its object It is in.

In order to achieve the above object, the O ₂ sensor mounting structure opens the downstream end of the exhaust pipe connected to the engine into the water, and the other end of the exhaust gas guide passage where one end opens into the engine cylinder hole or the exhaust passage. characterized allowed opening to the volume chamber, the O ₂ sensor mounting structure in a small boat comprising to face the O ₂ sensor in the container product chamber, in that the exhaust gas guide passage is inclined to be higher from one end to the other end And

In the O ₂ sensor mounting structure, the bottom wall of the volume chamber may be inclined so as to become lower toward the other end opening of the exhaust gas guide passage.

Another O ₂ sensor mounting structure for achieving the above object, the O ₂ sensor mounting structure in a small boat comprising brought open downstream end of the exhaust pipe connected to an engine into water, the exhaust passage of the engine O ₂ with to face the detection portion of the sensor, characterized in that allowed located above the detecting portions of the O ₂ sensor at least a portion of the exhaust pipe on the downstream side of the detecting portion of the O ₂ sensor.

Another O ₂ sensor mounting structure for achieving the above object, an opening is formed in the deck covering the engine upper, O ₂ sensor mounted in a small boat comprising covering the opening in an openable and closable lid The structure is characterized in that the detection portion of the O ₂ sensor faces the cylinder or the exhaust passage of the engine, and an exhaust pipe connected to the engine is positioned above at least a part of the O ₂ sensor.

In another O ₂ sensor mounting structure for achieving the above object, an opening is formed in a deck that covers the upper side of the engine, and the opening is covered with an openable / closable lid, and an intake pipe connected to the engine In an O ₂ sensor mounting structure in a small vessel in which an intake box is connected to the tip of the engine, a detection portion of the O ₂ sensor faces a cylinder hole or an exhaust passage of the engine, and the intake box is attached to at least the O ₂ sensor. It is characterized by being located above a part.

In another O ₂ sensor mounting structure for achieving the above object, an opening is formed in a deck covering the upper side of the engine, the opening is covered with a cover that can be opened and closed, and the cylinder axis of the engine is cranked. In the O ₂ sensor mounting structure in a small vessel inclined to one side of a vertical plane including the shaft center, the other end of the exhaust gas guide passage having one end opened in the cylinder hole of the engine is opened in the volume chamber, and the volume chamber O ₂ causes face the sensor, characterized in that allowed opposite space of the vertical plane across the cylinder axis as viewed the O ₂ sensor from the crank axis direction.

In another O ₂ sensor mounting structure for achieving the above object, an opening is formed in a deck covering the upper side of the engine, and the opening is covered with an openable / closable lid, and is connected to one side of the engine. In the O ₂ sensor mounting structure in a small vessel, the intake pipe is extended upward on one side of the engine and the exhaust pipe connected to the other side of the engine is extended upward on the other side of the engine. A volume chamber is provided above the cylinder upper wall of the engine, and the other end of the exhaust gas guide passage, one end of which opens into the cylinder hole of the engine, passes through the cylinder upper wall and opens into the volume chamber. The O ₂ sensor is faced, and the O ₂ sensor is positioned below the opening and in a space sandwiched between the intake pipe and the exhaust pipe.

Another O ₂ sensor mounting structure for achieving the above object, the O ₂ sensor mounting structure in a small boat formed by connecting the air intake pipe and an exhaust pipe to one side of the engine, the one side surface of the engine A volume chamber is formed in the vicinity of the side surface except for the other end of the exhaust gas guide passage, one end of which opens to the cylinder hole of the engine, and the O ₂ sensor faces the volume chamber. And

In the above O ₂ sensor mounting structure, “the downstream end of the exhaust pipe is open in water” means that at least the downstream end of the exhaust pipe is open in water while the ship is stopped. The downstream end of the exhaust pipe may be exposed in the water. The “exhaust passage” includes an exhaust passage formed in a cylinder as well as an exhaust passage formed in an exhaust pipe connected to the engine.

Further, in the mounting structure of the O ₂ sensor allowed to position at least a portion above the detecting section of the O ₂ sensor in the exhaust pipe, and "to face the sensing portion of the O ₂ sensor in the exhaust passage of the engine", the exhaust Of course, the case where the detection portion of the O ₂ sensor directly faces the passage includes the case where the detection portion of the O ₂ sensor faces the exhaust passage indirectly through the exhaust gas guide passage.

Also, "O ₂ at least a portion of the exhaust pipe on the downstream side of the detecting portion of the sensor allowed to position above the detection portion of the O ₂ sensor" refers to faces O ₂ directly to the detection unit is an exhaust passage of the sensor when on, it is sufficient that located above the detecting portions of the at least partially O ₂ sensor downstream of the exhaust pipe than the detection portion, the detection portion of the O ₂ sensor via the exhaust gas guide passage When it indirectly faces the exhaust passage, it is only necessary that at least a part of the exhaust pipe downstream of the opening portion of the exhaust gas guide passage with respect to the exhaust passage is located above the opening portion.

Therefore, according to the O ₂ sensor mounting structure in which the exhaust gas guide passage is inclined so as to increase from one end to the other end, even if water enters the volume chamber through the exhaust gas guide passage due to overturning of the ship or the like. The water that has entered the volume chamber is quickly discharged through the exhaust gas guide passage when the ship is restored, and the detection accuracy and durability of the O ₂ sensor are enhanced.

In addition, according to the O ₂ sensor mounting structure in which the bottom wall of the volume chamber is inclined so as to become lower toward the other end opening of the exhaust gas guide passage, the water that has entered the volume chamber is exhausted when the ship is restored or the like. Since the gas is discharged more rapidly through the gas guide passage, the detection accuracy and durability of the O ₂ sensor are further improved.

Further, according to at least a portion of the exhaust pipe to the mounting structure of the O ₂ sensor allowed to positioned above the detector of the O ₂ sensor, the water from the downstream end of the exhaust pipe to stop secondary engine toward the engine side even if backflow, the water is not able to reach the detector of the O ₂ sensor, detection accuracy and durability of the O ₂ sensor is enhanced.

Further, according to the exhaust pipe connected to an engine mounting structure of the O ₂ sensor allowed to position above at least a portion of the O ₂ sensor, subjected to inspection and maintenance of the engine through the opening to open the lid also water from the opening in which it infiltrates, this water without consuming blocked by the exhaust pipe O ₂ sensor, and the detection accuracy of the O ₂ sensor with a simple structure without requiring special parts Durability can be increased.

Also, according the concatenated air intake box to the tip of the intake pipe connected to the engine mounting structure of the O ₂ sensor allowed to position above at least a portion of the O ₂ sensor, via the opening to open the lid Even if water enters through the opening when checking and servicing the engine, this water is blocked by the intake box and does not get caught on the O ₂ sensor, and it does not require any special parts and has a simple configuration. Thus, the detection accuracy and durability of the O ₂ sensor can be improved.

Further, according to the O ₂ sensor to the mounting structure of the O ₂ sensor allowed to opposite space of the vertical plane containing the crankshaft axis across the crankshaft as viewed from the crankshaft direction, an opening to open the lid Even if water enters through the opening when checking or servicing the engine, the water is not blocked by the cylinder and does not get on the O2 sensor, and no special parts are required. The detection accuracy and durability of the O2 sensor can be improved.

Further, according to the O ₂ sensor mounting structure in which the O ₂ sensor is positioned below the opening formed in the deck covering the upper side of the engine and sandwiched between the intake pipe and the exhaust pipe, the O ₂ sensor is mounted on the deck. opening can be easily performed inspection and maintenance of the O ₂ sensor through, it is possible to ensure very high detection precision O ₂ sensor.

In addition, an intake pipe and an exhaust pipe are connected to one side of the engine, a volume chamber facing the O ₂ sensor is formed on a side other than the one side of the engine, and an exhaust gas guide passage having one end opened to the cylinder hole. According to the O ₂ sensor mounting structure in which the end is opened to the volume chamber, the intake pipe and the exhaust pipe are not obstructed to form the volume chamber, and a large volume can be secured in the volume chamber. .

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

<Embodiment 1>
FIG. 1 is a cutaway side view of the surface watercraft, FIG. 2 is a plan view of the surface watercraft with the deck removed, and FIG. 3 is a cutaway front view of the engine mounted on the surface watercraft as viewed from the front. .

  A hull 2 of a personal watercraft 1 shown in FIGS. 1 and 2 is configured by connecting a deck 2a made of FRP (fiber reinforced plastic) and a hull 2b with a gunnel 2c, and a longitudinal direction of an engine room S formed therein. A two-cycle two-cylinder engine 3 as a drive source is mounted in a substantially central portion (in FIG. 1 and the right is front). A fuel tank 4 is disposed in front of the engine 3. The upper part of the fuel tank 4 of the hull 2 is covered with a cowling 5, a steering handle 6 is obliquely erected outside the cowling 5 above the fuel tank 4, and a seat 7 is disposed behind the steering handle 6. Is arranged to be freely opened and closed. The engine room S of the hull 2 communicates with the atmosphere via front and rear air ducts 8 and 9.

  As shown in FIG. 2, the hull 2 (deck 2a) above the engine 3 has a rectangular opening 2d for maintenance, and the opening 2a is a lid that can be opened and closed freely. Covered by the sheet 7.

  By the way, the two-cycle engine 3 has two cylinders 3a arranged in parallel in the front-rear direction, and each cylinder 3a is arranged with respect to a vertical plane passing through the axis 11a of the crankshaft 11 as shown in FIG. It is inclined at a predetermined angle on the left side (left side in the direction of travel and on the right side in FIG. 3) so that the side faces are downward. The engine 3 is elastically supported on the bottom of the hull 2 via a plurality of engine mounts 12, and the crankshaft 11 is arranged in the front-rear direction of the hull 2. A spark plug 13 is attached to the top of each cylinder 3a.

  Further, an intake device 14 is connected to an end surface of the crankcase 3b of the engine 3 on the right side (right side in the traveling direction and left side in FIG. 3). The intake device 14 includes an intake pipe 15 provided for each cylinder and a common intake box 16 connected to the tip of each intake pipe 15. The intake pipe 15 and the intake box 16 are configured as described above. It arrange | positions diagonally so that V space may be formed between the cylinders 3a. As shown in FIG. 3, a throttle valve 17 is provided in each intake pipe 15 so that it can be opened and closed, and a reed valve 19 is provided in an intake passage 18 to which the intake pipe 15 of the crankcase 3b is connected. ing.

  Further, an exhaust passage 3c is opened on the left end surface (right end surface in FIG. 3) of each cylinder 3a of the engine 3, and an exhaust pipe 22 is connected to each exhaust passage 3c. The exhaust pipe 22 has an exhaust manifold 20 that collects two exhaust pipes led out from the two cylinders 3a into one.

  The exhaust pipe 22 extends substantially horizontally toward the rear in the V space formed between the intake device 14 and the cylinder 3a, and is then bent to the left at a substantially right angle. The water lock 23 is connected via a joint 21. The exhaust pipe 24 downstream of the water lock 23 is led out from the upper part of the water lock 23 and then extends upward. The exhaust pipe 24 extends substantially horizontally to the right and then is bent at a substantially right angle so as to be rearward. It extends obliquely downward, and its rear end is open to the water. Note that the exhaust pipe 24 has a rear end opened to the water when the watercraft 1 is anchored, but may be opened to the atmosphere when sailing.

  On the other hand, as shown in FIGS. 1 and 2, a propulsion unit 25 is disposed at the rear of the hull 2, and this propulsion unit 25 has a housing 26 that opens to the bottom of the ship and to the rear. An impeller shaft 27 arranged coaxially with the crankshaft 11 faces the housing 26, and the impeller shaft 27 is connected to the crankshaft 11 by a coupling 28. An impeller 29 housed in 26 is bound.

  Further, the rear end portion of the housing 26 is opened rearward, and a deflector 30 is attached to the opening portion so as to be swingable left and right. The deflector 30 is linked to the steering handle 6 via a cable (not shown), and the watercraft 1 is steered by changing the direction of the deflector 30 by a steering operation by the steering handle 6.

  As shown in FIGS. 1 and 2, a bilge suction port 31 is opened at the bottom of the engine compartment S, and the bilge suction port 31 is attached to the front end of the pipe 32. The end portion opens to a portion where negative pressure is generated, such as the downstream side of the impeller 29 of the propulsion unit 25. Accordingly, the water accumulated at the bottom in the engine room S is drawn by the negative pressure, is sucked from the bilge suction port 31, and is discharged out of the hull 2 through the pipe 32.

  As shown in FIG. 2, an engine control device (hereinafter referred to as an ECU) 34 and electrical components other than the ECU 34 (relays, rectifiers, ignition coils, etc.) are stored in a partition wall 33 provided in the hull 2. An electrical component storage box 35 is attached.

  By the way, the two-cycle engine 3 according to the present embodiment is a fuel injection engine (in-cylinder injection engine), and a high pressure is supplied from a delivery pipe 37 to an injector 36 attached to the intake side of each cylinder 3a. Fuel is sent and fuel is directly injected from each injector 37 into the cylinder of the engine 3 at an appropriate timing.

  Thus, as shown in FIG. 3, a piston 38 is slidably fitted in a cylinder hole 3d formed in each cylinder 3a of the engine 3, and this piston 38 is connected via a connecting rod (not shown). It is connected to the crankshaft 11. In addition to the exhaust passage 3c, a plurality of scavenging passages 3e are opened in the cylinder hole 3d of each cylinder 3a.

In addition, a bulging portion 39 is formed on the exhaust side of one of the cylinders 3a (front side in the present embodiment), and a volume chamber 40 is formed inside the bulging portion 39. An O ₂ sensor 41 is attached to the bulging portion 39, and the detection portion of the O ₂ sensor 41 faces the volume chamber 40. Here, the O ₂ sensor 41 is electrically connected to the ECU 34 (see FIG. 2). The volume chamber 40 may be formed integrally with the cylinder 3a as shown in FIG. 3, or may be formed separately. When formed separately, the volume chamber 40 may be slightly separated from the cylinder 3a.

  The volume chamber 40 communicates with the cylinder hole 3d through an exhaust gas guide passage 42 formed on the side wall of the cylinder 3a. The exhaust gas guide passage 42 extends from the opening end to the cylinder hole 3d. Inclined by a predetermined angle α with respect to the horizontal plane so as to become higher toward the opening end of the.

  In the present embodiment, the bottom wall 39a of the bulging portion 39 (the bottom wall of the volume chamber 40) is lowered toward the opening end of the exhaust gas guide passage 42 to the cylinder hole 3d in the axial direction of the cylinder 3a. It constitutes a slope like this.

Thus, when the engine 3 is driven, the fuel in the fuel tank 4 is boosted to a predetermined pressure by a fuel pump (not shown) and supplied from the delivery pipe 37 to each injector 36. Although it is directly injected into the cylinder hole 3d and used for combustion, a part of the exhaust gas generated in the cylinder hole 3d in the exhaust stroke is introduced into the volume chamber 40 through the exhaust gas guide passage 42. Then, the exhaust gas introduced into the volume chamber 40 is that O ₂ concentration is detected by the O ₂ sensor 41, the detection signal is transmitted to the ECU 34.

Then, the ECU 34 calculates the A / F of the air-fuel mixture based on the detection signal from the O ₂ sensor 41, and the actual A / F is determined according to the operating state of the engine 3 based on the calculated A / F. The fuel injection amount (fuel injection time) is controlled to be a value.

  When the engine 3 is driven by the control as described above, the rotation of the crankshaft 11 is transmitted to the impeller shaft 27 through the coupling 28, and the impeller shaft 27 and the impeller 29 attached thereto are given a predetermined value. Driven integrally at a speed.

  Thus, when the impeller 29 is rotationally driven as described above, the impeller 29 pressurizes the water sucked from the opening of the bottom of the ship in the housing 26 and injects the water backward from the deflector 30. The required propulsive force is generated by the water injection, and the watercraft 1 is caused to sail at a predetermined speed by the propulsive force.

As described above, in the present embodiment, the exhaust gas guide passage 42 for guiding the exhaust gas to the volume chamber 40 rises from the opening end to the cylinder hole 3d toward the opening end to the volume chamber 40 with respect to the horizontal plane. The bottom wall of the bulging portion 39 (bottom wall of the volume chamber 40) is formed at the opening end of the exhaust gas guide passage 42 to the cylinder hole 3d in the axial direction of the cylinder 3a. Even if water enters the volume chamber 40 through the exhaust gas guide passage 42 due to the rollover of the water planing boat 1 or the like, the water enters the volume chamber 40 because the slope is inclined so as to become lower. The discharged water is quickly discharged through the exhaust gas guide passage 42 when the watercraft 1 is restored. As a result, the detection accuracy and durability of the O ₂ sensor 41 are improved, and accurate air-fuel ratio control is performed. Is stable over the long term It takes place.

Further, in the present embodiment, as shown in FIG. 1, the crankshaft 11 and the impeller shaft 27 are inclined so as to become higher toward the front, and the volume chamber 40 in which the O ₂ sensor 41 is disposed is the frontmost cylinder hole. Since the opening is 3d, the position of the O ₂ sensor 41 can be increased, and the water accumulated on the bottom of the ship is less likely to get on the O ₂ sensor 41. This also increases the durability of the O ₂ sensor 41. .

  In this embodiment, the volume chamber 40 is formed in the front cylinder 3a. However, the volume chamber 40 may be formed in the rear cylinder 3a. The volume chamber 40 may be formed in the exhaust manifold 20 through an exhaust gas guide passage (not shown). You may make it connect with the exhaust pipe 22 or the exhaust passage 3c formed in the engine 3. FIG.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS. 4 is a cutaway side view showing the structure of the exhaust system of the watercraft showing the O ₂ sensor mounting structure according to the present embodiment, and FIG. 5 is a cutaway front view of the engine portion of the watercraft. In this figure, the same elements as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted below.

In the present embodiment, a bulging portion 39 is formed in a portion near the cylinder 3 a of the exhaust manifold 20, and a volume chamber 40 is formed therein, and the volume chamber 40 is an exhaust gas formed in the exhaust manifold 20. The exhaust manifold 20 communicates with the gas guide passage 42. An O ₂ sensor 41 is attached to the bulging portion 39, and the detection portion 41 a of the O ₂ sensor 41 faces the volume chamber 40. The bulging portion 39 may be formed integrally with the exhaust manifold 20 or may be formed separately.

  As shown in FIG. 4, in this embodiment, a part of the exhaust pipe 22 downstream of the opening to the exhaust manifold 20 in the exhaust gas guide passage 42 is connected to the exhaust manifold 20 in the exhaust gas guide passage 42. It is positioned above the opening.

  By the way, as shown in FIG. 4, a water jacket 20c is formed between the inner cylinder 20a and the outer cylinder 20b of the exhaust manifold 20, and the cooling water flowing through the water jacket 20c is within the exhaust manifold 20 at the portion A in the figure. Mixed with the exhaust gas flowing through. 3 and 4, the direction of the arrow F is the front. In FIG. 4, 43 is a catalyst, 44 in FIG. 5 is a fuel filter, and 45 is a pressure regulator.

Thus, in the present embodiment, a part of the exhaust gas flowing through the exhaust manifold 20 is introduced into the volume chamber 40 through the exhaust gas guide passage 42, and the exhaust gas introduced into the volume chamber 40 is O 2. The sensor 41 detects the O ₂ concentration, and the air-fuel ratio control of the air-fuel mixture is performed as in the first embodiment.

In this embodiment, a part of the exhaust pipe 22 on the downstream side of the opening of the exhaust gas guide passage 42 of the exhaust manifold 20 is located above the opening of the exhaust gas guide passage 42 to the exhaust manifold 20. Therefore, even if water flows backward from the downstream end of the exhaust pipe 22 toward the engine 3 while the engine 3 is stopped, the water is opened to the exhaust manifold 20 in the exhaust gas guide passage 42 (that is, O without reaching detection portion 41a of the _second sensor 41), therefore, O ₂ detection accuracy and durability of the sensor 41 is increased, stable similarly accurate air-fuel ratio control in the first embodiment is a long term Done.

In the present embodiment, the detection unit 41a of the O ₂ sensor 41 faces the volume chamber 40, but the detection unit 41a of the O ₂ sensor 41 may directly face the exhaust manifold 20. In this case, a part of the exhaust pipe 22 on the downstream side of the detection unit 41a of the O ₂ sensor 41 of the exhaust manifold 20 needs to be positioned above the detection unit 41a of the O ₂ sensor 41.

<Embodiment 3>
Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a cutaway front view of the engine portion of the personal watercraft according to the present embodiment as viewed from the front, and FIG. 7 is a plan view of the engine portion of the personal watercraft. The same elements as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted below.

In the present embodiment, the exhaust pipe 22 is positioned above at least a part of the O ₂ sensor 41 in the first embodiment, and the upper part of the O ₂ sensor 41 is covered by a part of the expansion chamber of the exhaust pipe 22. Is.

Thus, according to the present embodiment, when the seat 7 (see FIG. 1) as the lid is opened and the engine 3 is inspected and maintained through the opening 2d (see FIG. 7), the opening is opened. when water enters from the part 2d, this water without consuming blocked by the exhaust pipe 22 to the O ₂ sensor 41, and the high detection accuracy O ₂ sensor 41 with a simple structure without requiring special parts Durability can be ensured.

  In FIG. 7, the arrow F direction is the front.

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described with reference to FIGS. 8 is a cutaway front view of the engine unit of the personal watercraft according to the present embodiment as viewed from the front. FIG. 9 is a plan view of the engine part of the personal watercraft. The same elements as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted below.

In the present embodiment, a bulging portion 39 is formed integrally with the cylinder 3 a on the intake side of one (the front in this embodiment) cylinder 3 a, and a volume chamber 40 is formed inside the bulging portion 39. Is formed. An O ₂ sensor 41 is attached to the bulging portion 39, and the detection portion of the O ₂ sensor 41 faces the volume chamber 40.

  The volume chamber 40 communicates with the cylinder hole 3d through an exhaust gas guide passage 42 formed on the side wall of the cylinder 3a. As in the first embodiment, the exhaust gas guide passage 42 is connected to the cylinder hole 3d. Inclined so as to increase from the opening end to the volume chamber 40 toward the opening end.

Thus, in the present embodiment, the intake box 16 of the intake device 14 is positioned above the O ₂ sensor 41 and the intake box 16 covers the upper side of the O ₂ sensor 41. In the engine 3 according to the present embodiment, the injector 36 is attached to each intake pipe 15, and fuel is injected from the injector 36 into each intake pipe 15. In FIG. 9, the direction of arrow F is the front.

Therefore, according to the present embodiment, since the intake box 16 is positioned above the O ₂ sensor 41, the seat 7 (see FIG. 1) as a lid is opened and the engine 3 is inspected / opened through the opening 2d. Even if water enters through the opening 2d during maintenance, this water is not blocked by the intake box 16 and does not get on the O2 sensor 41, and requires special parts as in the third embodiment. High detection accuracy and durability can be ensured for the O ₂ sensor 41 with a simple configuration.

Further, in the present embodiment, as shown in FIG. 8, since the O ₂ sensor 41 is disposed in the vicinity of the air intake port 16a of the intake box 16, the O ₂ sensor 41 is cooled by the intake air flow. Further, the durability of the O ₂ sensor 41 is further enhanced.

<Embodiment 5>
Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a front view of the engine unit of the personal watercraft according to the present embodiment as viewed from the front. In FIG. 10, the same elements as those shown in FIG. The description about them is omitted.

In the present embodiment, as shown in FIG. 10, a maintenance opening 2d is formed in a deck 2a covering the upper side of the engine 3, and the opening 2d is covered with an openable / closable seat 7, and the cylinder of the engine 3 is covered. The shaft center is inclined to one side of the vertical plane including the crank shaft center, the intake pipe 15 and the exhaust manifold 20 are connected to one side surface of the cylinder 3a, and the volume chamber 40 is formed on the other side surface of the cylinder 3a. ing. Then, the other end of the exhaust gas guide passage 42 opened to the cylinder hole 3d of the engine 3 is opened to the volume chamber 40 so that the O ₂ sensor 41 faces the volume chamber 40, and the O ₂ sensor 41 is moved from the crankshaft direction. It is positioned in the space on the opposite side of the vertical plane with the cylinder shaft as viewed.

  In FIG. 10, 36 is an injector, 37 is a delivery pipe, and 46 is a fuel pump for supplying fuel from the fuel tank 4 to the delivery pipe 37.

Therefore, according to the present embodiment, the O ₂ sensor 41 is positioned in the space on the opposite side of the vertical plane including the crankshaft centered on the crankshaft when viewed from the crankshaft direction. Even if water enters through the opening 2d during inspection / maintenance of the engine 3 through the opening 2d, the water is blocked by the cylinder 3a and is difficult to get on the O ₂ sensor 41. The detection accuracy and durability of the O ₂ sensor 41 can be enhanced with a simple configuration without requiring parts.

In the present embodiment, the intake pipe 15 and the exhaust manifold 20 are connected to one side surface of the cylinder 3a of the engine 3, the volume chamber 40 is formed on the side surface except for one side surface of the cylinder 3a, and one end is a cylinder hole. Since the other end of the exhaust gas guide passage 42 that opens to 3d is opened to the volume chamber 40, the intake pipe 15 and the exhaust manifold 20 do not interfere with the formation of the volume chamber 40, and the volume chamber 40 has a large volume. Can be secured. Incidentally, since the exhaust gas is unevenly distributed in the cylinder hole 3d, if the volume of the volume chamber 40 is small and the sampling amount of the exhaust gas is small, O ₂ in the exhaust gas guided to the volume chamber 40 is small. The concentration depends on the non-uniform distribution of the exhaust gas in the cylinder hole 3d, and it becomes difficult to detect the average O ₂ concentration of the exhaust gas in the cylinder hole 3d. In this embodiment, the volume chamber 40 is used. Therefore, the average O ₂ concentration of the exhaust gas in the cylinder hole 3d can be detected.

  The volume chamber 40 may be slightly separated from the side surface of the cylinder 3a, the volume chamber 40 is formed in the vicinity of the front side surface or the rear side surface of the cylinder 3a, and the exhaust gas guide passage 42 is formed on the front side surface of the cylinder 3a. May penetrate the rear side surface.

<Embodiment 6>
Next, a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a cutaway front view of the engine portion of the personal watercraft according to the present embodiment as viewed from the front, and FIG. 12 is a plan view of the engine portion of the personal watercraft. In these drawings, FIG. The same elements as those shown in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted below. In FIG. 12, the direction of arrow F is the front.

  In the present embodiment, as shown in FIG. 11, an opening 2d for maintenance is formed in a deck 2a covering the upper side of the engine 3, and the opening 2d is covered with an openable / closable seat 7, and one of the cylinders 3a is covered. An intake pipe 15 connected to the cylinder 3a extends upward on one side of the cylinder 3a, and an exhaust pipe 22 connected to the other side of the cylinder 3a extends upward on the other side of the cylinder 3a.

A volume chamber 40 is formed integrally with the cylinder head 3f on the upper surface of the cylinder head 3f of the engine 3 constituting the cylinder 3a, and one end of the exhaust gas guide passage 42 penetrating the cylinder head 3f is connected to the combustion chamber of the engine 3. allowed open to 3g, with allowed to open the other end of the exhaust gas guide passage 42 into the volume chamber 40, the container product chamber 40 to face the sensing portion of the O ₂ sensor 41, the opening 2d of the O ₂ sensor 41 And a space sandwiched between the intake pipe 15 and the exhaust pipe 22.

Thus, according to the present embodiment, the O ₂ sensor 41 is positioned in the space between the intake pipe 15 and the exhaust pipe 22 below the opening 2d formed in the deck 2a covering the upper side of the engine 3. Therefore, the O ₂ sensor 41 can be easily inspected and maintained through the opening 2d formed in the deck 2a, and the O ₂ sensor 41 can always have high detection accuracy.

<Embodiment 7>
Next, a seventh embodiment of the present invention will be described with reference to FIG. FIG. 13 is a plan view of the engine according to the present embodiment, in which the direction of arrow F is the front.

The engine 3 according to the present embodiment is a two-cycle three-cylinder engine. Like the first embodiment, a volume chamber 40 is formed integrally with the cylinder 3a on the side wall of the foremost cylinder 3a. 40 communicates with the cylinder hole 3d through the exhaust gas guide passage 42. In the volume chamber 40, the detection unit of the O ₂ sensor 41 faces.

  Thus, in the present embodiment, the same effect as in the first embodiment can be obtained. However, in the engine 3 according to the present embodiment, the scavenging passages 3e and the exhaust passages 3c of each cylinder 3a are arranged in the cylinder axial direction. Inclined in the same direction (clockwise direction) with respect to a plane f orthogonal to the crankshaft passing through the cylinder axis 11a as seen, and adjacent scavenging passages 3e of adjacent cylinders 3a overlap each other in a side view of the engine. It is configured as follows. Therefore, the pitch between the cylinders 3a is shortened, and the length of the delivery pipe 37 that connects the injectors 36 can be shortened.

As apparent from the above description, according to the O ₂ sensor mounting structure in which the exhaust gas guide passage is inclined so as to increase from one end to the other end, the volume passes through the exhaust gas guide passage due to overturning of the ship or the like. Even if water enters the chamber, the water that has entered the volume chamber is quickly discharged through the exhaust gas guide passage when the ship is restored, etc., and the detection accuracy and durability of the O ₂ sensor are improved. It is done.

In addition, according to the O ₂ sensor mounting structure in which the bottom wall of the volume chamber is inclined so as to become lower toward the other end opening of the exhaust gas guide passage, the water that has entered the volume chamber is used when the ship is restored, etc. Since the exhaust gas is more rapidly discharged through the exhaust gas guide passage, the effect of further improving the detection accuracy and durability of the O ₂ sensor can be obtained.

Further, according to at least a portion of the exhaust pipe on the downstream side of the detecting portion of the O ₂ sensor to the mounting structure of the O ₂ sensor than the detection portion of the O ₂ sensor allowed to positioned above the exhaust pipe to stop secondary engine even if backflow water from the downstream end toward the engine side of the water without reaching detection portion of the O2 sensor, the effect is obtained that the detection accuracy and durability of the O ₂ sensor is enhanced.

Further, according to the exhaust pipe connected to an engine mounting structure of the O ₂ sensor allowed to position above at least a portion of the O ₂ sensor, subjected to inspection and maintenance of the engine through the opening to open the lid also water from the opening in which it infiltrates, this water without consuming blocked by the exhaust pipe O ₂ sensor, and the detection accuracy of the O ₂ sensor with a simple structure without requiring special parts The effect that durability can be improved is acquired.

Further, according the concatenated air intake box to the tip of the intake pipe connected to the engine mounting structure of the O ₂ sensor allowed to position above at least a portion of the O ₂ sensor, via the opening to open the lid Even if water enters through the opening when checking and servicing the engine, this water is blocked by the intake box and does not get caught on the O ₂ sensor, and it does not require any special parts and has a simple configuration. Thus, it is possible to improve the detection accuracy and durability of the O ₂ sensor.

Further, according to the O ₂ sensor to the mounting structure of the O ₂ sensor allowed to opposite space of the vertical plane containing the crankshaft axis across the crankshaft as viewed from the crankshaft direction, an opening to open the lid Even if water enters through the opening when checking or servicing the engine, the water is not blocked by the cylinder and does not get on the O ₂ sensor, and there is no need for special parts. Thus, it is possible to improve the detection accuracy and durability of the O2 sensor.

Further, according to the O ₂ sensor mounting structure in which the O ₂ sensor is positioned below the opening formed in the deck covering the upper side of the engine and sandwiched between the intake pipe and the exhaust pipe, the O ₂ sensor is mounted on the deck. opening can be easily performed inspection and maintenance of the O ₂ sensor through, there is an advantage that it is possible to ensure a consistently high detection precision O ₂ sensor.

In addition, an intake pipe and an exhaust pipe are connected to one side of the engine, a volume chamber facing the O ₂ sensor is formed on a side other than the one side of the engine, and an exhaust gas guide passage having one end opened to the cylinder hole. According to the O ₂ sensor mounting structure in which the end is opened to the volume chamber, the intake pipe and the exhaust pipe are not obstructed to form the volume chamber, and a large volume can be secured in the volume chamber. The effect is obtained.

1 is a cutaway side view of a personal watercraft according to Embodiment 1 of the present invention. It is a top view of the state which removed the deck of the personal watercraft which concerns on Embodiment 1 of this invention. It is the fracture | rupture front view which looked at the engine mounted in the water planing boat which concerns on Embodiment 1 of this invention from the front. Is a cutaway side view showing the configuration of an exhaust system of a hydroplane boat showing the O ₂ sensor mounting structure according to a second embodiment of the present invention. It is a fracture | rupture front view of the engine part of the personal watercraft which concerns on Embodiment 2 of this invention. It is the fracture | rupture front view which looked at the engine part of the surface watercraft based on Embodiment 3 of this invention from the front. It is a top view of the engine part of the personal watercraft which concerns on Embodiment 3 of this invention. It is the fracture | rupture front view which looked at the engine part of the surface watercraft based on Embodiment 4 of this invention from the front. It is a top view of the engine part of the personal watercraft which concerns on Embodiment 4 of this invention. It is the front view which looked at the engine part of the water planing boat concerning Embodiment 5 of the present invention from the front. It is the fracture | rupture front view which looked at the engine part of the surface watercraft based on Embodiment 6 of this invention from the front. It is a top view of the engine part of the personal watercraft which concerns on Embodiment 6 of this invention. It is a top view of the engine which concerns on Embodiment 7 of this invention.

Explanation of symbols

1 Water planing boat (small ship)
2 Hull 2a Deck 2d Opening 3 Engine 3a Cylinder 3c Exhaust passage 3d Cylinder hole 7 Seat (lid)
11 Crankshaft 11a Crankshaft center 15 Intake pipe 16 Intake box 20 Exhaust manifold (exhaust pipe)
22, 24 Exhaust pipe 40 Volume chamber 41 O ₂ sensor 41a O ₂ sensor detector 42 Exhaust gas guide passage.

Claims (2)

Forming an opening in the deck to cover the engine upper covers the opening in an openable and closable lid, the intake pipe connected to one side of the engine is extended toward one side upward of the engine, the intake box provided in an upper portion of the intake pipe, the O ₂ sensor mounting structure of the exhaust pipe connected to the other side of a small boat comprising by extending toward the other side upward of the engine of the engine,
The intake box is provided so that a lower surface thereof is positioned above the cylinder of the engine, and is disposed so as to be offset toward the cylinder side with respect to the intake pipe, and an air is provided on the lower surface of the intake box on the cylinder side. Forming the intake,
Provided the volume chamber communicating with the cylinder bore of the engine above the cylinders, the O ₂ sensor facing the volume chamber, a space sandwiched between the lower and the intake box of the opening and the exhaust pipe An O ₂ sensor mounting structure in a small vessel, characterized in that it is arranged closer to the intake box than a spark plug positioned above the cylinder . O in the small vessel according to claim 1 ₂ In the sensor mounting structure,
O in a small vessel characterized in that the volume chamber is arranged on the side of the lower surface of the intake box. ₂ Sensor mounting structure.

Images