JPH08135481A - Sensor protecting structure of air-fuel ratio control device for engine - Google Patents

Abstract

PURPOSE: To effectively improve the engine performance, and to effectively restrict the waste consumption of fuel by preventing the adhesion of the lubricating oil, which is led outside from an air cylinder together with the exhaust, to a sensor element part of an exhaust sensor. CONSTITUTION: A sensor element part 106 of an exhaust sensor 91 is faced to the flow of the exhaust 100, which is led outside from an air cylinder, and a protector 109 for this sensor element part is provided. This protector is formed of a container type protector main body 110 for covering the sensor element part and multiple small through holes 111, which are formed in the protector main body so as to allow the inside and outside of the protector main body to communicate with each other. Each through hole is displaced from the opposite surface 110a of the outer surface of the protector main body 110 opposite to the exhaust flow. Furthermore, a guide passage 115 for guiding exhaust outside of a system, and an accumulator chamber 119 communicating with this guide passage 115 are provided, and the sensor element part is faced to the exhaust flow inside of this accumulator chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine used for ships, motorcycles, automobiles and the like. More specifically, an exhaust sensor for detecting the property of exhaust gas is provided, and a cylinder is detected by a detection signal of the exhaust sensor. The present invention relates to a sensor protection structure in an engine air-fuel ratio control device that adjusts the air-fuel ratio of an air-fuel mixture sucked into the interior.

[0002]

2. Description of the Related Art Conventionally, some engines mounted on automobiles are constructed as follows.

That is, a mixture of air and fuel is appropriately supplied into the cylinder, and the mixture is burned in the cylinder to be converted into power. Burned gas is generated by the combustion. Then, the exhaust containing the burned gas is guided from the inside of the cylinder to the outside thereof.

As described above, the exhaust sensor is provided so that the sensor element portion faces the flow of the exhaust gas guided to the outside of the cylinder. This exhaust gas sensor detects the property of the exhaust gas, and the air-fuel ratio (A / F) of the air-fuel mixture is adjusted to a desired value by the detection signal, which improves the performance of the engine and wastes fuel. Consumption is being controlled. Further, a protector for the sensor element section is provided. This protector is composed of a container-shaped protector main body that covers the sensor element portion, and a large number of small-hole-shaped through-holes formed in the protector main body for communicating the inside and outside of the protector main body. Then, the exhaust gas comes into contact with the sensor element portion through these through-holes, whereby the property of the exhaust gas is detected as described above.

On the other hand, to lubricate the engine, lubricating oil is supplied into the cylinder together with the air-fuel mixture. After lubricating the cylinder, most of this lubricating oil is burned with the combustion of the air-fuel mixture, and the combustion gas of the lubricating oil generated by this combustion is contained in the exhaust gas and guided to the outside from the inside of the cylinder. . Further, in this case, a part of the lubricating oil remains unburned and is discharged together with the exhaust gas. In this case, it is suppressed by the protector body that the unburned oil that flows together with the exhaust gas tries to adhere to the sensor element portion.

[0006]

By the way, as described above, the attempt to attach the lubricating oil in the exhaust gas to the sensor element portion is suppressed by the protector body, but the lubricating oil is fine particles. However, there is a possibility that a part thereof will pass through the through-hole together with the exhaust gas and reach the sensor element portion and be attached thereto. If the lubricating oil adheres to the sensor element section, the detection accuracy and responsiveness of the exhaust sensor will deteriorate.

Therefore, even if the exhaust gas sensor detects the property of the exhaust gas, the property of the burned gas of the air-fuel mixture cannot be accurately grasped by this, that is, the air-fuel mixture supplied into the cylinder is not detected. It is supposed that the air-fuel ratio can not be grasped accurately.

Therefore, in the above-mentioned conventional structure, although the protector for the sensor element is provided, the adjustment of the air-fuel ratio based on the detection of the property of the exhaust cannot be made accurate to the desired value. However, there is a disadvantage that improvement of engine performance and suppression of wasteful consumption of fuel cannot be sufficiently achieved. Moreover, as described above, there is a problem in that the exhaust oil is deteriorated at an early stage due to the adhesion of the lubricating oil to the sensor element portion and the service life is shortened.

Further, when the engine is a two-cycle engine in particular, a blow-by phenomenon of fresh air may occur in the scavenging process, and in this case, in the exhaust gas, in addition to the burned gas, a new air is burned. O ₂ components in the air are mixed. The amount of this O ₂ component may reach about 100 times that of the O ₂ component in the burnt gas produced by combustion in the cylinder.

Therefore, based on the detection of the property of the exhaust gas by the exhaust sensor, the O ₂ component of the burnt gas obtained from this becomes much larger than the actual amount, that is, the property of the burnt gas also changes in this respect. There is a problem that it cannot be grasped accurately.

[0011]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above circumstances and prevents the lubricating oil introduced from the inside of a cylinder together with the exhaust from the outside thereof from adhering to the sensor element portion of the exhaust sensor. , So that the air-fuel ratio of the air-fuel mixture supplied to the cylinders can be accurately adjusted to a desired value, and thus it is possible to improve engine performance and suppress wasteful fuel consumption more effectively. To aim. Moreover, it aims at extending the life of the said exhaust gas sensor.

Further, even when the burnt gas produced by the combustion of the air-fuel mixture contains the O ₂ component in the fresh air and is exhausted as exhaust gas, it is detected in the cylinder based on the exhaust gas property detected by the exhaust gas sensor. It is an object of the present invention to be able to more accurately adjust the air-fuel ratio of the air-fuel mixture supplied to the engine to a desired value.

[0013]

A sensor protection structure in an air-fuel ratio control system for an engine according to the present invention for achieving the above object comprises a sensor element of an exhaust sensor in a flow of exhaust gas guided from the inside of a cylinder to the outside thereof. A protector for the sensor element portion, and a protector body in the form of a container that covers the sensor element portion and a small hole that is formed in the protector body and connects the inside and the outside of the protector body. When the air-fuel ratio of the air-fuel mixture sucked into the cylinder is adjusted by the detection signal of the exhaust sensor, the exhaust gas out of the outer surface of the protector body The through-holes are deviated from the surface of the facing portion facing the flow of the above.

In the above case, a guide passage for guiding the exhaust to the outside of the system and a pressure accumulating chamber communicating with the guide passage may be provided, and the sensor element portion may be exposed to the flow of the exhaust in the pressure accumulating chamber.

[0015]

[Operation] The operation of the above configuration is as follows.

The sensor element portion 106 of the exhaust gas sensor 91 is exposed to the flow of the exhaust gas 100 guided from the inside of the cylinders 16 to 18 to the outside thereof, and the sensor element portion 106 is also exposed.
A protector 109 is provided, and the protector 109 is a container-shaped protector main body 110 that covers the sensor element portion 106, and a large number of small-hole-shaped through-holes formed in the protector main body 110 for communicating the inside and the outside of the protector main body 110. When the air-fuel ratio of the air-fuel mixture 99 sucked into the cylinders 16 to 18 is adjusted by the detection signal of the exhaust sensor 91, the outer surface of the protector main body 110 , The exhaust 100
The through-holes 111 are offset from the surface 110a of the facing portion facing the flow of the above.

Therefore, when a part of the lubricating oil supplied into the cylinders 16 to 18 becomes unburned oil and is discharged together with the exhaust gas 100 and flows toward the sensor element section 106 together with the exhaust gas 100, this lubricating oil is discharged. , The protector body 110
The lubricating oil flows so as to separate from the sensor element portion 106 by colliding with the surface 110 a of the facing portion 110 or changing the flow by the surface 110 a of the facing portion.

In this case, although the lubricating oil is fine particles, it has a larger inertial force than that of the exhaust gas 100. Therefore, the lubricating oil that has come off the sensor element portion 106 as it is and the exhaust gas 100 and its downstream side. It flows toward the side and prevents the lubricant oil from adhering to the sensor element portion 106.

In the above structure, a guide passage 115 for guiding the exhaust 100 to the outside of the system is provided, a pressure accumulating chamber 119 communicating with the guide passage 115 is provided, and the exhaust sensor 91 is provided in the flow of the exhaust 100 in the pressure accumulating chamber 119. Sensor element part 10
6 may be made to face, and the property of the exhaust 100 of the said accumulator 119 may be detected by the said exhaust sensor 91.

In this case, the exhaust gas 100 having a large pressure passes through the guide passage 115 and the pressure accumulating chamber 11
If it flows into 9, the large pressure of the exhaust gas 100 is once stored in the pressure storage chamber 119. Therefore, immediately after this, even if the exhaust gas 100 having a low pressure tries to flow into the pressure accumulating chamber 119, this flow is blocked. And
The exhaust sensor 91 detects the property of the exhaust 100 having a large pressure.

By the way, particularly the two-cycle engine 10
Then, the pressure in the cylinders 16 to 18 becomes the maximum pressure in the "explosion process", and the pressure is gradually reduced as the "scavenging process" is started.

In the "explosion process", the cylinders 16 to 1
Most of the exhaust gas 100 to be led out from the inside of the cylinder 8 is composed of burnt gas, and at the maximum pressure, the cylinders 16 to 18 are almost filled with burned gas.

On the other hand, in the "scavenging process", the exhaust gas 100 is guided from the inside of the cylinders 16 to 18 to the outside through, for example, the exhaust passages 43, 47, 48. Immediately after the exhaust, the exhaust passages are exhausted. 43,4
The maximum pressure is inside 7, 48, and the above pressure gradually decreases as the scavenging progresses.

Then, the exhaust 100 passes through the exhaust passage 43,
Immediately after being discharged into the exhaust passages 47, 48, the scavenging has just started, and the amount of fresh air blown into the exhaust passages 43, 47, 48 is small.
Most of the exhaust gas 100 in 47, 48 is composed of burnt gas, that is, the exhaust passages 43, 47, 48 are almost filled with burned gas at the maximum pressure.

Therefore, in the cylinders 16 to 18 and the exhaust passage 4
Most of the exhaust 100 that produces the maximum pressure in the exhaust system such as 3, 47, 48 is composed of burnt gas, and the exhaust 100 having a high pressure is used in the guide passage 11
When the gas flows into the pressure accumulating chamber 119 through No. 5, the exhaust gas 100
Most of them are burnt gas.

As described above, once the exhaust gas 100 having a large pressure is stored in the pressure accumulating chamber 119, immediately after that, the fresh air mixture 99 containing a large amount of O ₂ component flows into the pressure accumulating chamber 119. Attempts to prevent this inflow will this be due to the low pressure. Therefore, as described above, the properties of the exhaust 100, which is mostly burned gas, are detected by the exhaust sensor 91.

Therefore, based on the detection by the exhaust sensor 91, the air-fuel ratio of the air-fuel mixture 99 at that time can be accurately grasped, and according to this, the subsequent air-fuel ratio can be adjusted to a desired value more accurately. You can

[0028]

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

(Example 1)

1 to 10 show the first embodiment.

In FIG. 2, reference numeral 1 is a ship as an example of a vehicle, and an arrow Fr indicates the front of the ship 1 in the traveling direction. The right and left described below means the direction toward the front.

The boat 1 has a hull 2, and an outboard motor 3 is detachably attached to the stern of the hull 2. The outboard motor 3 includes a bracket 4 attached to the stern.
And an outboard motor body 6 pivotally supported by a pivot shaft 5 with respect to the bracket 4.

The outboard motor main body 6 is provided with a power transmission device 8, and the power transmission device 8 is composed of a transmission case 9 constituting an outer shell thereof and a transmission mechanism housed in the transmission case 9. The transmission case 9 is pivotally supported on the bracket 4 by the pivot shaft 5. The outboard motor body 6 is a two-cycle multi-cylinder engine 1 which is an internal combustion engine.
This engine 10 is detachably attached to the upper end of the transmission case 9 and is covered with a cover 11 so as to be openable and closable. The transmission case 9 extends downward into the water and has a cylindrical shaft 13 at the lower end of the transmission case 9.
And a propeller 14 is attached to the shaft 13.

Then, the propeller 14 is provided to the output portion of the engine 10 via the transmission mechanism of the power transmission device 8.
Are linked to work together.

2 to 8, the engine 10 is shown.
Is the first cylinder 16, the second cylinder 17, and the third cylinder 18
Of a plurality of (three) cylinders, and these cylinders are arranged side by side so as to be vertically stacked.

The engine 10 includes the cylinders 16-1.
8 has a common crankcase 19, and this crankcase 19 has a vertically oriented crankshaft 20 whose axis is substantially vertical.
The crankshaft 20 is rotatably supported by the crankcase 19 about its axis.

The cylinder main bodies 22 of the cylinders 16 to 18 are integrally attached to the rear portion of the crankcase 19, and the axes of the cylinder main bodies 22 extend forward and backward in parallel with each other. A cylinder head 23 is detachably attached to the protruding end of each of the cylinder bodies 22. The cylinder bodies 22 are integrated with each other to form a cylinder block 24, and the cylinder heads 23 are also integrated with each other.

Each of the cylinder main bodies 22 has a cylinder hole 25 in which the axial center extends in the front-rear direction, and a piston 26 is slidably inserted in the front-rear direction in the cylinder hole 25. Each of these pistons 26 is connected to the crankshaft 20 by a connecting rod 27.

In the cylinder hole 25, the cylinder head 2
The space surrounded by 3 and the piston 26 corresponds to the "inside of the cylinder", and the above "inside of the cylinder" where the piston 26 is close to the cylinder head 23 to some extent becomes the combustion chamber 29. Three spark plugs 30 are attached to the cylinder head 23 so as to correspond to the combustion chambers 29, and the discharge portions 31 of the spark plugs 30 face the combustion chambers 29.

Three intake ports 33 are formed on the front surface of the crankcase 19, and a reed valve 34 is attached to each of the intake ports 33. In addition, the intake manifold 35,
A throttle body 36 that houses the throttle valve 36a,
And the silencer 37 is successively arranged. An inlet pipe 38 that opens rearward is attached to the upper end of the silencer 37. The inlet pipe 38, silencer 37, throttle body 36, intake manifold 3
5 and the reed valve 34 are communicated with each other by an intake passage 39 provided inside each of them.
Moreover, each of the intake passages 39 communicates with the intake port 33.

The throttle valves 36a are connected to the interlocking means 40.
Are connected to each other. When the operator operates the operation section, the throttle valves 36a are synchronized with each other via the interlocking means 40 to perform the same opening / closing operation.

A plurality of (three) scavenging passages 41 are formed for each cylinder hole 25 in the cylinder body 22 around each cylinder hole 25. Each of these scavenging passages 41 is arranged in the combustion chamber 2 inside the crankcase 19.
It communicates with 9.

An exhaust manifold 42 is attached to the left side of the cylinder block 24, and one end side of the first exhaust passage 43 in the exhaust manifold 42 is branched into a plurality (three) and formed in each cylinder body 22. Exhaust port 4
It opens to each combustion chamber 29 through 4. On the other hand, an exhaust guide 46 is provided between the cylinder block 24 and the transmission case 9, and the second exhaust passage 47 in the exhaust guide 46 and the other end side of the first exhaust passage 43 communicate with each other. Has been made. A third exhaust passage 48 is formed in the transmission case 9, one end of the third exhaust passage 48 communicates with the second exhaust passage 47, and the other end opens into the water through the shaft 13.

4 and 7, the engine 10 is provided with a water cooling type cooling device 50. The cooling device 50 includes a first cooling water jacket 51 formed in the cylinder block 24 around each cylinder hole 25, a second cooling water jacket 52 formed in the exhaust manifold 42, and the second exhaust passage 47. A third cooling water jacket 53 formed in the exhaust guide 46 so as to surround the cooling water, and a fourth cooling water jacket 54 formed in the transmission case 9 so as to surround the third exhaust passage 48. The jackets 51 to 54 communicate with each other directly or via the cooling water communication passage 55. The lower end of the fourth cooling water jacket 54 communicates with the downstream side of the third exhaust passage 48.

A water pump for supplying cooling water 56 such as seawater is provided to the first cooling water jacket 51, and the cooling water 56 sequentially passes through the cooling water jackets 51 to 54 through the cooling water communication passage 55. And, it is drained into the water through the downstream end of the third exhaust passage 48. Then, in the middle of this flow, the cooling water 56 cools the first to third cylinders 16 to 18, whereby the first to third cylinders 1
6-18 cylinder heads 23 and cylinder blocks 24
Are kept in a predetermined temperature range.

In FIG. 2, fuel 5 is supplied to the engine 10.
A fuel supply device 60 for supplying 9 is provided. The fuel supply device 60 has a plurality (three) of fuel injection valves 61 corresponding to the first to third cylinders 16 to 18, and each of these fuel injection valves 61 is detachably attached to the throttle body 36. . These fuel injection valves 61 appropriately inject fuel 59 into the intake passage 39 extending from the throttle body 36 to the reed valve 34.

A low-pressure fuel pump 64 that sucks and supplies the fuel 59 stored in the fuel tank 63 to each of the fuel injection valves 61, and a high-pressure fuel pump that pressurizes and supplies the fuel 59 from the low-pressure fuel pump 64. 65 are provided in series. A water separation filter 66 and a vapor separator 67 are connected in series between the low pressure fuel pump 64 and the high pressure fuel pump 65. Further, as described above, the pressure regulator 69 that adjusts the pressure of the fuel 59 supplied to the fuel injection valve 61 to a predetermined pressure is provided, and the above devices are connected to each other by the fuel passage 70.

Each of the fuel injection valves 61 is of an electromagnetic type, and when it is electrically turned on (or off), the period is set as a fuel injection period, and the fuel 59 only in this period is the intake passage 3.
It is designed to be injected within 9.

In the above case, only the fuel tank 63 of the fuel supply device 60 is supported by the hull 2, and the others constitute the outboard motor 3.

In FIG. 2, an engine control device 73 for controlling the engine 10 is provided. The engine control device 73 includes an electronic control device body 74,
The ignition plugs 30, the fuel injection valve 61, the low pressure fuel pump 64, and the high pressure fuel pump 65 are electrically connected to the control device main body 74. A flywheel magnet 75 is attached to the upper end of the crankshaft 20. The flywheel magneto 75 supplies power to the control device main body 74 directly or via a battery.

Various sensors for detecting the driving state of the engine 10 are provided, and all of these are electrically connected to the control device main body 74.

That is, as the sensors, a crank angle sensor 76 for detecting the rotation angle of the crankshaft 20, a crankcase internal pressure sensor 77 for detecting the pressure in the crankcase 19, and a pressure in each cylinder 16-18 are detected. An in-cylinder pressure sensor 78, a knock sensor 79 for detecting a state inside the cylinders 16 to 18, an intake temperature sensor 80 for detecting a temperature in the intake passage 39, and a throttle opening sensor 81 for detecting an opening of the throttle body 36 are provided. Has been.

Further, a cylinder temperature sensor 82 for detecting the temperature of each cylinder 16-18, a back pressure sensor 83 for detecting the upstream pressure in the third exhaust passage 48, an atmospheric pressure sensor 84 for detecting the atmospheric pressure, and a cooling. A cooling water temperature sensor 85 for detecting the temperature of the water 56, a shift sensor 86 for detecting the shift state of the power transmission device 8, and a trim angle sensor 87 for detecting the vertical rotation position of the outboard motor 3 around the pivot shaft 5 are provided. It is provided.

On the other hand, an air-fuel ratio control device 89 is provided, and this air-fuel ratio control device 89 is provided with an exhaust gas introducing means 90 and an exhaust gas sensor 91 provided in this exhaust gas introducing means 90.

In addition, 93 is a starter and 94 is an oil tank.

2 to 8, when the engine 10 is driven and the piston 26 moves from the bottom dead center position on the crankshaft 20 side to the combustion chamber 29 side in each of the first to third cylinders 16 to 18, The scavenging passage 41 and the exhaust port 44 are sequentially closed by the piston 26. Further, when the piston 26 moves to the combustion chamber 29 side in this way, the inside of the crankcase 19 becomes negative pressure. Then, the silencer 37, the throttle body 36, the intake manifold 35, the reed valve 34, and the intake passage 39 in the intake port 33 sequentially become negative pressure, and the outside air 97 which is air 97
Is sucked into the intake passage 39 from the intake port 33.

Next, the fuel injection valve 61 is connected to the intake air 98.
The fuel 59 is injected by and the air-fuel mixture 99 is generated. Then, this air-fuel mixture 99 becomes the crankcase 19 described above.
Inhaled into. This is the "inhalation process".

On the other hand, after the scavenging passage 41 and the exhaust port 44 are closed as described above, when the piston 26 is further moved to the combustion chamber 29 side, the air-fuel mixture already sucked into the combustion chamber 29 is moved. 99 are compressed. This is the "compression process".

Immediately before the piston 26 reaches the top dead center, the mixture 99 is ignited and burned by the discharge of the discharge part 31 of the spark plug 30 controlled by the engine control device 73, and the gas expands. As a result, the piston 26 is pushed back to the crankshaft 20 side after passing the top dead center. This is the "explosion process".

The movement of the piston 26 toward the crankshaft 20 pre-compresses the air-fuel mixture 99 sucked into the crankcase 19. The reed valve 34 is closed by the pressure at this time.

During the movement of the piston 26 toward the crankshaft 20, the exhaust port 44 is opened first. Then, through the exhaust port 44, the exhaust gas 100, which is the burned gas of the air-fuel mixture 99, is led out through the exhaust port 44. This is the "exhaust process".

The exhaust gas 100 is guided so as to sequentially pass through the first exhaust passage 43, the second exhaust passage 47, the third exhaust passage 48, and the shaft 13, and is exhausted into the water. In this case, the cooling water 56 after cooling the cylinders 16 to 18 passes through the fourth cooling water jacket 54 and the cooling water communication passage 55, and is discharged into the water together with the exhaust 100.

When the piston 26 moves to the crankshaft 20 side and the exhaust port 44 is opened as described above, the scavenging passage 41 is subsequently opened. Then, as described above, the air-fuel mixture 99 that has been pre-compressed in the crankcase 19 is discharged.
Is introduced into the combustion chamber 29 through the scavenging passage 41, and the air-fuel mixture 99 pushes out a portion of the burned gas remaining in the combustion chamber 29 into the first exhaust passage 43, and 99 fills the combustion chamber 29. This is the "scavenging process". And after this, the piston 26
Returns to the bottom dead center position.

In the above case, some of the air-fuel mixture 99 which has flowed into the combustion chamber 29 through the scavenging passage 41 is blown to the first exhaust passage 43 side (this is referred to as "fresh air blow-through phenomenon"). It is mixed with burnt gas and is discharged as the exhaust 100.

From the above state, the piston 26 moves to the combustion chamber 29 side again, and the above-described processes are repeated to rotate the crankshaft 20. Then, the engine 10 outputs power through the crankshaft 20, and this power causes the propeller 14 to rotate via the power transmission device 8 to allow the ship 1 as a driven body to travel.

FIG. 10 is a diagram showing the movement of the piston 26. In this figure, the first cylinder 16, the second cylinder 17,
And the third cylinder 18 has a crank angle of 12 in this order.
Drive with a phase difference of 0 °.

1 to 9, the exhaust sensor 9
Reference numeral 1 is for detecting the properties of the exhaust 100. The detection signal of the exhaust sensor 91 is input to the control device main body 74, and the control of the control device main body 74 controls the length of the fuel injection period of the fuel injection valve 61 to be short or long.
The air-fuel ratio (A / F) of the air-fuel mixture 99 is automatically adjusted to an appropriate value.

In this case, the crank angle sensor 7
The driving state of the engine 10 is input to the control device main body 74 by various sensors such as No. 6, and the fuel injection period of the fuel injection valve 61 is controlled by the control device main body 74 so that the air-fuel ratio becomes a desired value. It is supposed to be done. In this way, the engine performance is improved and the fuel
The useless consumption of 9 is suppressed.

In FIG. 9, the exhaust sensor 91 is O ₂
A sensor, which is configured as follows.

That is, the exhaust sensor 91 has a circular protective outer cylinder 104 made of sheet metal, and a fastener 105 is attached to one end of the protective outer cylinder 104. Further, the same as above, a sensor element portion 106 made of zirconia is housed in the protective outer cylinder 104, and one end of this sensor element portion 106 has the protective outer cylinder 1
It projects from one end of 04. The sensor element unit 106
A lead wire 107 is provided for electrically connecting the control device body 74 to the control device body 74.

A hollow portion 108 is formed inside the sensor element portion 106. Same as above, platinum electrodes are plated on both the inside and outside surfaces of the sensor element portion 106, and the oxygen concentration, which is the property of the exhaust 100, is detected by the electromotive force generated according to the difference in oxygen concentration inside and outside the sensor element portion 106. .

Further, a protector 109 for the sensor element section 106 is provided. This protector 109 is a cylindrical container-shaped protector main body 110 made of sheet metal that covers the protruding end of the sensor element section 106, and the protector main body 1
The protector main body 110 is detachably attached to one end of the protective outer cylinder 104. The protector main body 110 is detachably attached to one end of the protective outer cylinder 104. In addition, each through hole 1
The exhaust 100 freely flows through the inside and outside of the protector body 110 through 11 and can come into contact with the sensor element section 106.

Further, a ceramic heater 112 is provided in the sensor element portion 106, and the heater 112 is provided.
By appropriate heating of the sensor element unit 106 by
The accuracy of the exhaust sensor 91 is improved.

Further, all the parts such as the protective outer cylinder 104 and the like constituting the exhaust sensor 91 are located on the same axis 113 and have an elongated shape as a whole.

1 to 9, the exhaust gas introduction means 90 of the air-fuel ratio control device 89 has a guide passage 115 for guiding the exhaust gas 100 to the outside of each cylinder hole 25 outside the system, and this guide passage 115. Is a circular metal guide pipe 11
It is composed of 6.

The one end opening 117 of the guide passage 115 is
The second cylinder 17, which is an example of a certain cylinder, has an opening “inside the cylinder”, and the one end opening 117 is opened and closed by the operation of the piston 26 of the second cylinder 17. Also,
Same as above, the other end opening 118 of the guide passage 115 opens "in the cylinder" of the first cylinder 16 which is an example of another cylinder, and the other end opening 118 is opened and closed by the operation of the piston 26 of the first cylinder 16. It is supposed to do.

In the above case, the one end opening 117 is the other end opening 1
It is located slightly closer to the top dead center (combustion chamber 29) side than 18. The one-end opening 117 is located slightly above the top dead center side end of the exhaust port 44 (or at substantially the same position as the top dead center side end of the exhaust port 44), and
It is located closer to the top dead center than the scavenging port 41a. Further, the other end opening 118 is located slightly on the top dead center side of the scavenging port 41a (or at substantially the same position as the top dead center side end of the scavenging port 41a).

A pressure accumulating chamber 119 having a cross-sectional area sufficiently larger than that of the guide passage 115 is provided in the middle of the guide passage 115. The pressure accumulating chamber 119 is formed by a sheet metal accumulating case 120 having a rectangular parallelepiped shape.

In FIG. 1, the pressure accumulating chamber 119 will be described in more detail. The midway portion of the guide passage 115 is divided, and one dividing end 122 on the one end opening 117 side of the guide passage 115 is the above-mentioned. It is connected to the lower wall of the pressure accumulating case 120 and opens into the pressure accumulating chamber 119. Also,
The other split end 123 of the guide passage 115 on the other end opening 118 side is connected to the upper wall of the pressure accumulating case 120 and opens into the pressure accumulating chamber 119.

The exhaust sensor 91 is detachably fastened to the rear wall of the pressure accumulating case 120 by a fastener 105,
The protruding end of the sensor element portion 106 and the protector 109 covering the protruding end face the inside of the pressure accumulating chamber 119 in the pressure accumulating case 120.

Of the outer surface of the protector body 110, the through holes 111 are offset from the facing portion surface 110a facing the flow of the exhaust gas 100 in the pressure accumulating chamber 119, that is, the facing portion surface 110a. The through-hole 111 does not exist, and is kept closed. More specifically, each through hole 111 is offset from the vicinity of the extension line of the axial center of the one dividing end 122, and flows into the pressure accumulating chamber 119 through the one dividing end 122. It is prevented that the exhaust 100 passes through the through hole 111 and directly faces the sensor element portion 106.

In FIG. 10, in each phase of the cylinders 16 to 18, the exhaust port 44 opens about 90 ° from the top dead center (a portion in FIG. 10), and the scavenging port 41a opens about 120 ° ( (Part b in FIG. 10). Also,
At about 240 °, the scavenging port 41a of the same as above is closed (part c in FIG. 10), and at about 270 °, the exhaust port 4 of the same as above.
4 is closed (part d in FIG. 10) and returns to the top dead center. Less than,
This is repeated.

3 to 6 and FIG. 10, the other end opening 118 immediately after the scavenging port 41a is opened by the sliding of the piston 26 in the "exhaust process" and the "scavenging process" of the first cylinder 16. Is opened "in the cylinder" (A part in FIG. 10). Then, the high-pressure exhaust gas 100 accumulated in the pressure accumulating chamber 119 in advance passes through the other end opening 118 and the first cylinder 1
6 is released into the “in-cylinder”, and the pressure accumulated in the pressure accumulating chamber 119 decreases (A to B in FIG. 10). The opening of the other end opening 118 means full opening, and the opening of one end opening 117 described later also means full opening.

When the pressure in the accumulator 119 drops to some extent, the piston 26 slides in the "explosion process" of the second cylinder 17 immediately before the exhaust port 44 opens (or almost at the same time), and the scavenging port 41a. Before opening, the one end opening 117 is opened to “inside the cylinder” of the second cylinder 17 (see B part in FIG. 10). At this time, the second cylinder 17
Is immediately after the "explosion process", and the pressure of the exhaust 100 in the "in-cylinder" of the second cylinder 17 is high.
00 vigorously flows from the one-end opening 117 through the guide passage 115 into the pressure accumulating chamber 119 and is sufficiently accumulated therein, and the pressure in the accumulating chamber 119 rapidly increases (B to C in FIG. 10).
Part).

As described above, the one end opening 117 of the guide passage 115 in the second cylinder 17 is located at the top dead center side of the scavenging port 41a. Therefore, the "explosion process" of the second cylinder 17 is caused. The sliding of the piston 26 at “” causes the one end opening 117 to open at a timing earlier than that of the scavenging port 41a. Therefore, the high-pressure exhaust gas 100 smoothly flows into the accumulator chamber 119 through the one-end opening 117, and at that pressure, the air-fuel mixture 9 that has flowed into the “in-cylinder” through the scavenging port 41a that opens thereafter.
9 is prevented from flowing into the pressure accumulating chamber 119. Further, at this time, as described above, a part of the exhaust gas 100 in the high-pressure accumulator chamber 119 flows back into the “inside cylinder” of the second cylinder 17, so that the mixture 99 flows into the accumulator chamber 119 more. Certainly blocked.

Further, as described above, the one end opening 117 is caused by the sliding of the piston 26 in the "explosion process" of the second cylinder 17.
When the exhaust gas 100 is stored in the pressure accumulating chamber 119 between the time when the scavenging port 41a is opened and the time when the scavenging port 41a is opened. The volume of the pressure accumulating chamber 119 is set so that the pressure of the exhaust gas 100 in the pressure accumulating chamber 119 is kept higher than the pressure, so that the mixture 99 flows more reliably into the pressure accumulating chamber 119. Be blocked by.

On the other hand, as described above, immediately after the one end opening 117 of the second cylinder 17 is opened "in the cylinder",
Immediately before opening the scavenging port 41a, the other end opening 118 is closed in the first cylinder 16 (C in FIGS. 3, 5, and 10).
Part).

In portions B to C in FIG. 10, the reference numeral E in FIG. 10 is the same as in FIG. 10 except that the other end opening 118 is “in the cylinder” of the first cylinder 16.
The pressure at the other end opening 118 when it is opened. Further, reference symbol F in FIG. 10 indicates the pressure of the one-end opening 117 when the one-end opening 117 is opened “in the cylinder” of the second cylinder 17.

Further, P _{0 in} FIG. 10 is the maximum pressure in the “in-cylinder” of the first cylinder 16 when the other end opening 118 is open in the “in-cylinder” of the first cylinder 16. Further, the maximum pressure in the “in-cylinder” of the second cylinder 17 when the one-end opening 117 is opened in the “in-cylinder” of the second cylinder 17 is almost the same as P ₀ .

Then, the exhaust gas 100 in the pressure accumulating chamber 119.
The minimum pressure of is maintained at a high pressure above the maximum pressure P ₀ . Therefore, the “scavenging process” of the first cylinder 16
Then, even if the air-fuel mixture 99 in the “in-cylinder” of the first cylinder 16 tries to flow into the pressure accumulating chamber 119 through the other end opening 118, this is lower than the maximum pressure P _{0, and} therefore the air-fuel mixture is The inflow of 99 into the pressure accumulating chamber 119 is blocked.

Thereafter, the one-end opening 117 is opened "in the cylinder" of the second cylinder 17 until the second cylinder 17 shifts from the "intake process" to the "compression process", and the exhaust port 44 is opened.
Is closed immediately (or almost at the same time) (part D in FIG. 10).

As described above, the other end opening 1 is formed in the first cylinder 16.
18 is closed and the open end 117 of the second cylinder 17 is open (portions C to D in FIG. 10), the pressure accumulating chamber 1 having a high pressure.
From within 19, as described above, "in the cylinder" of the second cylinder 17
A reverse flow of the exhaust gas 100 occurs (in the direction of the imaginary line arrow in FIGS. 1, 5, and 6), and the pressure in the pressure accumulating chamber 119 decreases.

After that, both the one end opening 117 and the other end opening 118 are kept closed (FIG. 10).
(Middle D to A parts), the pressure in the pressure accumulating chamber 119 leaks to each “in-cylinder” of the first cylinder 16 and the second cylinder 17, and gradually decreases.
After that, the process returns to the portion A in FIG. 10 and the above-described operation is repeated.

When the other end opening 118 of the first cylinder 16 is opened again at the portion A in FIG.
6, the pressure in the "in-cylinder" is low immediately after the scavenging port 41a is opened as described above.
Between the parts, the exhaust gas 100 in the accumulator 119 flows into the “in-cylinder” of the first cylinder 16 through the other end opening 118.

The one end opening 117 is the other end opening 11
Since the second cylinder 17 is located on the top dead center side, the opening of the one end opening 117 of the second cylinder 17 when viewed from the top dead center is the other end opening 118 of the first cylinder 16 when viewed from the top dead center. Faster than timing, that is,
The pressure at the one end opening 117 when the one end opening 117 is opened (B portion in FIG. 10) is larger than the pressure at the other end opening 118 when the other end opening 118 is opened (A portion in FIG. 10). Become.

Therefore, in the second cylinder 17, one end opening 11 is formed.
When 7 is opened (B portion in FIG. 10), the exhaust gas 100 of the second cylinder 17 more smoothly flows into the pressure accumulation chamber 119 through the opening 117 at the one end and is sufficiently accumulated in the pressure accumulation chamber 119.

As a result of the above, the exhaust 100 of the second cylinder 17 can be reliably introduced into the pressure accumulating chamber 119 for each cycle. In addition, the air-fuel mixture 99, which is fresh air containing a large amount of O ₂ component, enters the accumulator 119 from the second cylinder 17 and the first cylinder 16.
Are prevented from flowing in.

Then, in the portions C to D in FIG.
The properties of the exhaust gas 100 in the pressure accumulating chamber 119 are detected by the exhaust gas sensor 91. In this case, in the “explosion process” in the second cylinder 17, the exhaust gas 10 generated in the second cylinder 17 is detected.
Since 0 is mostly composed of burnt gas, and is filled with the exhaust gas 100 of the second cylinder 17 while blocking the inflow of the air-fuel mixture 99 into the pressure accumulating chamber 119 as described above, The accumulator 119 will be filled with the burned gas generated in the second cylinder 17. Therefore, since the air-fuel mixture 99 is not mixed, the property of the exhaust 100 in each cycle of the second cylinder 17 is accurately detected by the exhaust sensor 91, that is, the O ₂ concentration is detected with high accuracy.

The opening 117 on one end is defined by the piston 26.
May be opened toward the top dead center side so that it always remains open regardless of the operation of
17 may be formed on the cylinder head 23.

In FIG. 1, in order to lubricate the engine 10, the lubricating oil is supplied to the "inside cylinders" of the first to third cylinders 16 to 18 together with the air-fuel mixture 99. This lubricating oil is supplied to lubricate the engine 10,
Almost all of them are combusted with the combustion of the air-fuel mixture 99 to become combustion gas, but a part of this lubricating oil remains unburned and is discharged from the “in-cylinder” together with the exhaust 100.

In the above case, the fine particles of the lubricating oil, which is an unburned oil, together with the exhaust gas 100 flow in the pressure accumulating chamber 119 on one of the dividing ends 1.
Although it flows from 22 toward the other divided end 123 side, as described above, the protector 109 for the sensor element unit 106 is provided.
Of the outer surface of the protector body 110 of FIG.
Is deviated, the lubricating oil flowing toward the sensor element portion 106 together with the exhaust 100 collides with the facing portion surface 110a of the protector body 110, or the flow is changed by the facing portion surface 110a. The lubricating oil flows so as to separate from the sensor element portion 106.

In this case, although the lubricating oil is fine particles, it has a larger inertial force than that of the exhaust gas 100. Therefore, the lubricating oil that has come off the sensor element section 106 remains as it is along with the exhaust gas 100. It flows toward the other divided end 123 side of the side, and the adhesion of the lubricating oil to the sensor element portion 106 is prevented.

Therefore, the exhaust gas 1 by the exhaust gas sensor 91 is
The detection accuracy and responsiveness of the property of 00 are improved.

Then, as described above, the exhaust sensor 91
A highly accurate and highly responsive detection signal detected by the above is input to the control device main body 74 of the engine control device 73. Therefore, based on this input signal, the mixture is supplied "in the cylinder" at that time. The calculation of the actual air-fuel ratio of the air 99 is performed accurately.

On the other hand, the control device main body 74 is supplied with the respective detection signals of the throttle opening sensor 81, the cylinder temperature sensor 82, etc., and the drive state of the engine 10 is judged based on these input signals. A target air-fuel ratio suitable for the state is determined.

Then, the actual air-fuel ratio and the target air-fuel ratio are compared with each other, whereby the injection conditions such as the fuel injection period (injection amount) by the fuel injection valve 61 are determined, and the subsequent mixture 99 The air-fuel ratio is automatically adjusted to a desired value that matches the driving state of the engine 10.

Although the above is based on the illustrated example, the engine 10 may be a 4-cycle engine. The engine 10 may be driven by an industrial machine other than a vehicle. In addition, the sensor element portion 106 is provided in the exhaust 1
You may face in the flow of 00.

Further, the pressure accumulating chamber 119 does not need to be provided in the middle of the guide passage 115, but may be connected to the end of the guide passage 115. That is, for example, in FIG. 1, the upper guide passage 115 of the pressure accumulating chamber 119 may be eliminated and only the lower guide passage 115 may be provided. In this case, the exhaust gas 100 that has flowed into the accumulator 119 through the lower guide passage 115.
In the period from B to D in FIG. 10, when the pressure in the second cylinder 17 becomes lower than the pressure in the pressure accumulating chamber 119, the backflow occurs in the second cylinder 17.

(Example 2)

11 to 16 show the second embodiment.

11 to 13, the guide passage 11
The one end opening 117 of No. 5 is the above-mentioned first example which is an example of a certain cylinder.
The opening is made “inside the cylinder” of the cylinder 16, and the one end opening 117 is provided.
Is opened and closed by the operation of the piston 26 of the first cylinder 16. Further, the other end opening 118 of the guide passage 115 opens to “inside the cylinder” of the third cylinder 18 which is an example of another cylinder, and the other end opening 118 operates the piston 26 of the third cylinder 18. It is designed to open and close.

14 and 15, the pressure accumulating chamber 119 is constructed as follows.

That is, the pressure accumulating chamber 119 formed in the pressure accumulating case 120 is composed of an upper chamber 134 and a lower chamber 135 which are vertically arranged close to each other. One dividing end 122 of the guide passage 115 is opened through a plurality of first throttle portions 136 with respect to an intermediate portion in the vertical direction of the lower chamber 135. Further, the other divided end 123 of the guide passage 115 is opened to the bottom surface 132 of the lower chamber 135 through a drain hole 139 having the shape of a throttle. Further, one of the divided ends 122 of the guide passage 115 is short-circuited to a middle portion of the other divided end 123 in the vertical direction through the bypass passage 140 formed in the pressure accumulating case 120.

On the other hand, a second throttle portion 141 communicating with the lower chamber 135 is formed on the bottom surface 132 of the upper chamber 134, and the first throttle portion 136 and the second throttle portion 141 constitute the throttle portion 131. are doing. In addition, the second throttle unit 1
41 also serves as a drain hole, and is the bottom surface 1 of the upper chamber 134.
The reference numeral 32 is an inclined surface 132a which is inclined downward as it goes toward the second throttle portion 141.

An exhaust sensor 91 is attached to the pressure accumulating case 120 so that the sensor element portion 106 and the protector 109 face the upper chamber 134 of the pressure accumulating chamber 119. In this case, the through holes 111 are deviated from the facing surface 110a of the outer surface of the protector body 110 that faces the flow of the exhaust gas 100 in the upper chamber 134. More specifically, the throttle unit 131
The through holes 111 are deviated from the vicinity of the extension line of the axis of the second throttle portion 141.

11 to 16, the third cylinder 18
In the “exhaust process” and the “scavenging process”, the other end opening 118 is opened in the combustion chamber 29 immediately after the scavenging port 41a is opened by the sliding of the piston 26 in the third cylinder 18 (FIG. 16). Middle part A). Then, the exhaust gas 100 accumulated in the pressure accumulating chamber 119 in advance passes through the other end opening 118 and is released into the third cylinder 18, and the pressure accumulated in the pressure accumulating chamber 119 is reduced (A in FIG. 16). ~ Part B).

While the pressure in the accumulator 119 is decreasing, the piston 26 in the first cylinder 16 slides,
The one-end opening 117 is opened in the combustion chamber 29 immediately before the exhaust port 44 opens (or almost at the same time) and before the scavenging port 41a opens (B portion in FIG. 16). At this time, the first cylinder 16 is immediately after the “explosion process”, and the pressure of the exhaust gas 100 in the first cylinder 16 is high.
Is vigorously flowed into the pressure accumulating chamber 119 from the opening 117 through the guide passage 115 and is sufficiently accumulated therein, and the pressure in the accumulating chamber 119 rapidly rises (B to C in FIG. 16).

On the other hand, the one end opening 117 is the other end opening 11
Since it is located on the top dead center side with respect to No. 8, the timing at which the other end opening 118 in the third cylinder 18 opens is the first cylinder 1
6, the timing at which the one end opening 117 opens is delayed, and the pressure at the one end opening 117 when the one end opening 117 opens is larger than the pressure at the other end opening 118 when the other end opening 118 opens. Become.

Therefore, when the one end opening 117 is opened as described above, the exhaust gas 100 of the first cylinder 16 becomes the above one end opening 11
7 and the one divided end 122 to flow into the pressure accumulating chamber 119, and is sufficiently accumulated in the pressure accumulating chamber 119.

Next, as described above, immediately after the one end opening 117 of the first cylinder 16 is opened "in the cylinder",
The other end opening 118 is closed in the third cylinder 18 (C portion in FIG. 16). After that, the one-end opening 117 is closed when the first cylinder 16 shifts from the “suction process” to the “compression process” (portion D in FIG. 16).

As described above, while the other end opening 118 is closed and the one end opening 117 is open (C to D in FIG. 16).
Part), a reverse flow of the exhaust gas 100 occurs from the inside of the pressure accumulation chamber 119 having a high pressure to the first cylinder 16 (in the direction of the imaginary line arrow in FIG. 14), and the pressure of the pressure accumulation chamber 119 decreases.

After that, both the one end opening 117 and the other end opening 118 are kept closed (FIG. 16).
(Parts D to A), the pressure in the pressure accumulating chamber 119 gradually decreases due to leakage into the first cylinder 16 and the third cylinder 18. After that, the process returns to the portion A in FIG. 16 and the above operation is repeated.

When the other end opening 118 is opened again at the portion A in FIG. 16, immediately after the scavenging port 41a is opened in the third cylinder 18, the pressure "in the cylinder" is low, so
6 between A and C, the pressure accumulating chamber 11 passes through the other end opening 118.
The exhaust gas 100 in 9 flows into the “inside cylinder” of the third cylinder 18.

Then, in the portions C to D in FIG. 16,
The exhaust sensor 91 detects the property of the exhaust gas 100 in the upper chamber 134 of the pressure accumulating chamber 119. In this case, in the “explosion process” in the first cylinder 16, most of the exhaust gas 100 that is about to be discharged from the first cylinder 16 is composed of burnt gas, so the accumulator 119 is set to burn the burned gas. Will be satisfied with. Therefore, since the air-fuel mixture 99 is not mixed, the property of the exhaust gas 100 is accurately detected by the exhaust gas sensor 91.

As described above, the exhaust gas 1 in the first cylinder 16
00 flows into the pressure accumulating chamber 119 through the guide passage 115 (B to C in FIG. 16), the guide passage 115
Exhaust gas 10 from one divided end 122 toward the pressure accumulating chamber 119
A part of 0 flows into the lower chamber 135 through the first throttle 136. Further, the other part of the exhaust gas 100 in the guide passage 115 and most of the lubricating oil particles in the exhaust gas 100 are sent to the bypass passage 140 by the inertial force thereof, and from there to the other divided end 123 side of the guide passage 115. I will be told.

In the above case, the exhaust gas 100 flowing into the lower chamber 135 through the first throttle portion 136 is the same as the first throttle portion 1 described above.
The exhaust 10 because it suddenly changes direction when passing through 36
The lubricating oil is separated from 0 by inertial force, that is, the lower chamber 13
The exhaust gas 100 having a reduced content of lubricating oil is allowed to flow into the valve 5.

Further, the exhaust gas 1 flowing into the lower chamber 135
00 is made to flow into the upper chamber 134 through the second throttle portion 141. At this time, since the volume of the lower chamber 135 is large, the flow velocity of the exhaust gas 100 in the lower chamber 135 sharply decreases. Therefore, most of the lubricating oil particles in the exhaust gas 100 are on the bottom surface 132 of the lower chamber 135 due to their gravity. It is turned to and separated. Then, the lubricating oil accumulated on the bottom surface 132 is discharged to the other divided end 123 side through the drain hole 139.

Further, the fine particles of the lubricating oil that have flowed into the upper chamber 134 together with the exhaust gas 100 are the bottom surface 1 of the upper chamber 134.
When it tries to collect on 32, this lubricating oil
It is directed to the second throttle portion 141 above a, discharged through the second throttle portion 141 to the lower chamber 135 side, and further discharged through the drain hole 139 to the other divided end 123 side.

On the other hand, when the backflow of the exhaust gas 100 occurs from the pressure accumulating chamber 119 to the first cylinder 16 as described above (FIG. 16).
Middle C to D parts, direction of imaginary line arrow in FIG. 14,), upper chamber 1
Lubricating oil that tries to collect on the bottom surface 132 of 34 passes through the second throttle portion 141 more smoothly and is discharged to the lower chamber 135 side.

In the above case, the exhaust gas 100 in the upper chamber 134 reaches the upper chamber 134 by passing through the first throttle portion 136 and the second throttle portion 141 from the one divided end 122 side. Since the amount of the lubricating oil contained therein is sufficiently reduced in two stages, the lubricating oil is more reliably suppressed from adhering to the sensor element portion 106 of the exhaust sensor 91.

Particularly, in FIG. 14, one of the divided ends 12 is
2 is located above the other split end 123.

Therefore, the lubricating oil flowing into the pressure accumulating chamber 119 through the one divided end 122 together with the exhaust gas 100 is divided into the other divided end 123 by the inertia force and the natural flow.
And is smoothly discharged from the pressure accumulating chamber 119.

Therefore, it is suppressed that the lubricating oil stays in the pressure accumulating chamber 119, and accordingly, the adhesion of the lubricating oil to the sensor element portion 106 of the exhaust sensor 91 is further suppressed.

Since other structures and operations are the same as those in the first embodiment, the same reference numerals are given to the drawings and the description thereof will be omitted.

[0135]

According to the present invention, the sensor element portion of the exhaust sensor is made to face the flow of the exhaust gas guided from the inside of the cylinder to the outside thereof, and the protector for the sensor element portion is provided. A cylinder-shaped protector main body that covers the sensor element portion, and a large number of small through-holes formed in the protector main body that communicate the inside and the outside of the protector main body. When the air-fuel ratio of the air-fuel mixture sucked in is adjusted, the through holes are deviated from the surface of the outer surface of the protector body facing the exhaust flow.

Therefore, when a part of the lubricating oil supplied to the cylinder becomes unburned oil and is discharged together with the exhaust gas and flows toward the sensor element portion together with the exhaust gas, this lubricating oil is opposed to the protector body. By colliding with the surface of the part or by changing the flow by the surface of the facing part, the lubricating oil flows so as to separate from the sensor element part.

In this case, although the lubricating oil is fine particles, it has a larger inertial force than exhaust gas. Therefore, the lubricating oil that has come off the sensor element portion goes directly to the downstream side together with the exhaust gas. And the lubricant oil is prevented from adhering to the sensor element portion.

Therefore, since the detection accuracy and responsiveness of the exhaust gas property by the exhaust gas sensor are improved, the air-fuel ratio of the air-fuel mixture at that time is more accurately grasped based on the detection of the exhaust gas property. The subsequent air-fuel ratio can be adjusted to a desired value more accurately. As a result,
Improved engine performance and wasteful fuel consumption are suppressed.

Further, as described above, since the lubricating oil is prevented from adhering to the sensor element portion, the life of the exhaust sensor can be improved.

In the above structure, a guide passage for guiding the exhaust to the outside of the system is provided, a pressure accumulating chamber communicating with the guide passage is provided, and the sensor element portion of the exhaust sensor is exposed to the flow of the exhaust in the pressure accumulating chamber. The exhaust gas property of the pressure accumulating chamber may be detected by the exhaust gas sensor.

In this case, if the exhaust gas having a large pressure flows into the pressure accumulating chamber through the guide passage, the large pressure of the exhaust gas is temporarily accumulated in the accumulating chamber. Therefore, immediately after this, even if the exhaust gas having a low pressure tries to flow into the pressure accumulating chamber, the inflow is blocked.
Then, the property of the exhaust gas having the large pressure is detected by the exhaust gas sensor.

By the way, particularly in the case of a two-cycle engine, the pressure in the cylinder becomes the maximum pressure in the "explosion process", and the above pressure gradually decreases as it goes toward the "scavenging process".

In the "explosion process", most of the exhaust gas to be led out from the inside of the cylinder is composed of burnt gas, and at the maximum pressure, the inside of the cylinder is almost burnt gas. be satisfied.

On the other hand, in the "scavenging process", exhaust gas is guided from the inside of the cylinder to the outside through, for example, the exhaust passage. Immediately after this exhaust, the inside of the exhaust passage reaches the maximum pressure and the scavenging proceeds. Accordingly, the pressure is gradually reduced.

Immediately after the exhaust gas is discharged into the exhaust passage, the scavenging has just started, and the amount of fresh air blown into the exhaust passage side is small. Is composed of burnt gas, that is, the inside of the exhaust passage is almost filled with burnt gas at the maximum pressure.

Therefore, most of the exhaust gas that produces the maximum pressure in the exhaust system such as in the cylinder and in the exhaust passage is composed of burnt gas, and the exhaust gas having a large pressure passes through the guide passage and accumulates in the pressure accumulating chamber. Most of the above exhaust gas is burnt gas when flowing into the.

As described above, once the exhaust gas having a large pressure is accumulated in the pressure accumulating chamber, immediately after that, O ₂
Even if a fresh air mixture containing a large amount of components tries to flow into the pressure accumulating chamber, the pressure is low, so that the inflow is blocked. Therefore, as described above, the properties of the exhaust gas, which is almost burnt gas, are detected by the exhaust gas sensor.

Therefore, based on the detection by the exhaust sensor, as described above, the fact that the lubricant oil is prevented from adhering to the sensor element portion and the air-fuel ratio of the air-fuel mixture at that time is accurate. According to this, it is possible to more accurately adjust the subsequent air-fuel ratio to a desired value. As a result, improvement of engine performance and suppression of wasteful fuel consumption are achieved more effectively.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of FIG. 3 in Embodiment 1.

FIG. 2 is a general diagram of the first embodiment.

FIG. 3 is a side view of the engine according to the first embodiment.

FIG. 4 is a rear partial cross-sectional view of the engine according to the first embodiment.

5 is a sectional view taken along line 5-5 of FIG. 3 in Example 1. FIG.

6 is a sectional view taken along line 6-6 of FIG. 3 in the first embodiment.

FIG. 7 is a bottom partial cross-sectional view of the lower portion of the outboard motor in the first embodiment.

FIG. 8 is a plan view of the engine according to the first embodiment.

FIG. 9 is a vertical cross-sectional view of the exhaust sensor according to the first embodiment.

FIG. 10 is an operation explanatory diagram based on the engine cycle according to the first embodiment.

FIG. 11 is a diagram corresponding to FIG. 3 in the second embodiment.

FIG. 12 is a diagram corresponding to FIG. 4 in the second embodiment.

FIG. 13 is a diagram corresponding to FIG. 8 in the second embodiment.

FIG. 14 is a diagram corresponding to FIG. 1 in the second embodiment.

15 is a partially enlarged partial cross-sectional view of FIG. 11 in Embodiment 2. FIG.

FIG. 16 is a diagram corresponding to FIG. 10 in the second embodiment.

[Explanation of symbols]

 10 Engine 16 First Cylinder (Cylinder) 17 Second Cylinder (Cylinder) 18 Third Cylinder (Cylinder) 43 First Exhaust Passage (Exhaust Passage) 47 Second Exhaust Passage (Exhaust Passage) 48 Third Exhaust Passage (Exhaust Passage) 89 Air-fuel ratio control device 91 Exhaust sensor 99 Air-fuel mixture 100 Exhaust 106 Sensor element part 109 Protector 110 Protector body 110a Facing part surface 111 Through hole 115 Guide passage 119 Accumulation chamber 120 Accumulation case

Claims (2)

[Claims] 1. A container for exposing a sensor element part of an exhaust sensor to the flow of exhaust gas guided from the inside of a cylinder to the outside thereof, providing a protector for the sensor element part, and covering the sensor element part with the protector. -Like protector body and a large number of small hole-shaped through-holes formed in the protector body for communicating the inside and outside of the protector body, and the mixture is sucked into the cylinder by the detection signal of the exhaust sensor. In the sensor protection structure in the engine air-fuel ratio control device for adjusting the air-fuel ratio of air, in the outer surface of the protector body, the through holes are offset from the surface of the facing portion facing the flow of exhaust gas. Sensor protection structure for the air-fuel ratio control system of the engine. 2. The method according to claim 1, further comprising a guide passage for guiding the exhaust to the outside of the system, and a pressure accumulating chamber communicating with the guide passage, wherein the sensor element portion is exposed to the flow of the exhaust in the pressure accumulating chamber. Sensor protection structure in the air-fuel ratio control system for the engine of the above.