JP4447527B2 - Air-cooled internal combustion engine - Google Patents

Description

The present invention relates to an air-cooled internal combustion engine including an O ₂ sensor that measures an oxygen concentration in exhaust gas.

As an air-cooled internal combustion engine, one that measures the oxygen concentration in exhaust gas and calculates the optimum air-fuel ratio according to the operating condition of the engine based on the lowest value of this oxygen concentration is known. In such an air-cooled internal combustion engine, an O ₂ sensor that measures the oxygen concentration in the exhaust gas is disposed in the middle of the exhaust pipe (see, for example, Patent Document 1).

JP-A-9-189250 (2nd page, FIG. 1)

By the way, in the air-cooled internal combustion engine described in Patent Document 1, the O ₂ sensor is disposed in the middle of the exhaust pipe that guides the exhaust from the exhaust port of the engine to the outside. For this reason, it is necessary to protect the O ₂ sensor from collisions such as foreign objects during traveling, for example, stepping stones from the road surface, and in particular, in the case of a vehicle in which the cylinder of the engine is mounted substantially horizontally with respect to the vehicle body. Since the exhaust pipe is disposed near the road surface, its protection structure is complicated.

Conventionally, in order to prevent damage to the O ₂ sensor due to such foreign matter, but the structure so as to protect to attach the protective cover to the O ₂ sensor is generally known, in this case, the O ₂ sensor As the number of parts such as a protective cover increases, there is a problem that the assembling property is lowered and the manufacturing cost is increased.

The present invention has been made in view of the above-described problems. The object of the present invention is to protect the O ₂ sensor from foreign matters such as stepping stones without providing a dedicated part such as a cover, thereby improving the assemblability. It is possible to provide an air-cooled internal combustion engine that can reduce the manufacturing cost.

In order to achieve the above object, an invention according to claim 1 is an air-cooled internal combustion engine provided with an O ₂ sensor for measuring an oxygen concentration in exhaust gas, wherein a cooling fin is provided in a cylinder head of the internal combustion engine, The O ₂ sensor is provided between the cooling fins, and the cooling fin is divided by the O ₂ sensor .

According to the second aspect of the invention, in addition to the configuration of the first aspect of the invention, the air-cooled internal combustion engine is mounted on the vehicle body with the cylinder head forward and the cylinder substantially horizontal, and the O ₂ sensor is And provided between the cooling fins on the side surface of the cylinder head.

In the invention according to claim 3, in addition to the configuration of the invention according to claim 1 or 2, the cooling fin on the side surface of the cylinder head is provided substantially horizontally with respect to the advancing direction, and is back and forth by the O ₂ sensor. It is divided.

According to the air-cooled internal combustion engine according to claim 1, since the O ₂ sensor is provided between the cooling fins and the cooling fin is divided by the O ₂ sensor , the cooling fin has a function of protecting the O ₂ sensor. The O ₂ sensor can be protected from foreign matters such as stepping stones. In addition, since dedicated parts such as a protective cover for the O ₂ sensor are not necessary, the assembly of the O ₂ sensor can be improved, and the manufacturing cost can be reduced.

According to the air-cooled internal combustion engine according to claim 2, the air-cooled internal combustion engine is mounted on the vehicle body with the cylinder head forward in the traveling direction and the cylinder substantially horizontal, and the O ₂ sensor is a cooling fin on the side of the cylinder head. because provided between, as compared with the case of arranging the O ₂ sensor in the exhaust pipe, it is possible to arrange the O ₂ sensor at a position away from the road surface. Thereby, the possibility of damage to the O ₂ sensor due to foreign matters such as stepping stones can be greatly reduced.

According to the air-cooled internal combustion engine of the third aspect, the cooling fin on the side surface of the cylinder head is provided substantially horizontally with respect to the traveling direction, and is divided into two parts by the O ₂ sensor. While being able to protect the O ₂ sensor, it is possible to reduce the turbulence of the air flow in the vicinity of the cooling fin by the O ₂ sensor, and to prevent the air cooling efficiency from being lowered.

Hereinafter, an embodiment of an air-cooled internal combustion engine according to the present invention will be described in detail with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
1 to 6 show an embodiment of the present invention, FIG. 1 is a side view of a vehicle equipped with an air-cooled internal combustion engine according to the present invention, and FIG. 2 illustrates an air-cooled internal combustion engine according to the present invention. FIG. 3 is a cross-sectional view taken along a line connecting the cylinder head, cylinder block, crankshaft, input shaft, and output shaft of the power unit, FIG. 3 is an enlarged cross-sectional view of the cylinder head of the power unit shown in FIG. 5 is a side view of the power unit shown in FIG. 4 as viewed from the right side, FIG. 5 is a longitudinal sectional view of the cylinder head and cylinder block shown in FIG. 4, and FIG. 6 is a front view of the cylinder head with the cylinder head cover removed. It is the figure seen from. In the following description, front and rear, left and right, and top and bottom are indicated as Fr in the front, Rr in the rear, L in the left, R in the left, R in the right, U in the upper, and D in the lower according to the direction viewed from the driver.

  As shown in FIG. 1, a motorcycle 10 is pivotally supported by a body frame (vehicle body) 11, a front fork 12 that is pivotally supported on a front portion of the body frame 11, and a lower end portion of the front fork 12. A front wheel 13, a bar-like handle 14 connected to the upper end of the front fork 12, a rear fork 15 whose front end is pivotally supported by the vehicle body frame 11 and extending rearward, and a rear end of the rear fork 15. And a power unit (air-cooled internal combustion engine) 1 is suspended at the center lower portion of the vehicle body frame 11.

  The power unit 1 is configured by integrating an internal combustion engine and a load-side transmission mechanism, and the output of the power unit 1 is transmitted to a rear wheel 16 via a chain 17. The power unit 1 is connected to an exhaust pipe 18 extending rearward. The exhaust pipe 18 is connected to a muffler 19 disposed on the right side of the rear wheel 16.

  As shown in FIG. 2, the power unit 1 is an air-cooled four-stroke cycle single-cylinder internal combustion engine, in which the axis of the crankshaft 100 is orthogonal to the traveling direction of the vehicle and the cylinder block 40 is directed forward. The motorcycle 10 is mounted on the motorcycle 10 so as to be substantially horizontal along the traveling direction.

  The power unit 1 includes a left and right half unit case 2L and a right unit case 2R in which a crankcase of an internal combustion engine and a gear case of a transmission mechanism are integrated, a cylinder block 30, a cylinder head 40, a cylinder head cover 41, The crankcase 3 and the gear formed by joining the crankcase cover 51, the right crankcase cover 52, and the gear case cover 53 to form an outer shell and joining the left and right unit cases 2L and 2R. The chamber 4 is provided with a crankshaft 100 and a transmission 200, respectively. Note that a left crankcase cover 51 and a gear case cover 53 are bolted to the left side surface of the left unit case 2L, and the right side of the right unit case 2R. The right crankcase cover 52 is bolted to the surface.

  The cylinder head 40 is attached by being fastened together with the stud bolt 60 together with the cylinder block 30 inserted into the upper openings of the combined left and right unit cases 2L and 2R. Further, the opening is closed by fastening the cylinder head cover 41 to the cylinder head 40 with bolts 61 (see FIG. 3). A combustion chamber 42 is formed on the lower surface of the cylinder head 40, and a spark plug 43 is attached so as to face the combustion chamber 42. Further, a plurality of cooling fins 21 are formed on the side surfaces of the cylinder block 30 and the cylinder head 40.

  A cam shaft 44 of a valve operating mechanism is rotatably supported in the cylinder head 40, and a cam sprocket 45 is fixed to the left end portion thereof. A cam chain 98 spanned over a drive sprocket 102 fixed to the crankshaft 100 is spanned over the cam sprocket 45. As a result, the rotational driving force of the crankshaft 100 is transmitted to the camshaft 44 to drive the roller rocker-type rocker arms 46 and 46 disposed in the cylinder head 40, and the intake valve (see FIG. 5) in the combustion chamber 42. 47) The exhaust valve (see FIG. 5) 48 is opened and closed at a predetermined timing.

  The crankshaft 100 is composed of left and right parts, and is integrated by a crankpin 101. The crankshaft 100 is rotatably supported via rolling bearings 70L and 70R disposed in the left and right unit cases 2L and 2R, respectively. The AC generator 90 is assembled on the left side in the axial direction, and the centrifugal multi-plate clutch 91 is assembled on the right side in the axial direction. A piston 32 is connected to the crankpin 101 via a connecting rod 31, and the piston 32 reciprocates in the cylinder axis direction in a cylinder liner 33 integrally formed in the cylinder block 30.

  The AC generator 90 generates a high voltage to be applied to the spark plug 43 through an ignition coil (not shown) and generates a charging current for a battery (not shown).

  The centrifugal multi-plate clutch 91 is a wet centrifugal multi-plate clutch and is assembled to the right side of the crankshaft 100. The inner plate 91a is spline-coupled to the crankshaft 100, and rotates integrally with the inner plate 91a. The outer case 91b, the plurality of clutch plates 91c attached to the inner peripheral surface of the outer case 91b, the plurality of clutch disks 91d arranged alternately between the plurality of clutch plates 91c, and the plurality of clutch disks 91d are supported. A plate support member 91e, a clutch weight 91f pivotally supported on the outer peripheral portion of the inner plate 91a, a pivot shaft 92 attached to the right crankcase cover 52, and a left end portion of the pivot shaft 92 are disposed. An outer case 91b is rotatably supported via a bearing 71. The pressure plate 93 to the body rotated, rotates the clutch lifter lever (not shown), and a clutch lifter cam plate 94 to move forward and backward in the axial direction (lateral direction in FIG. 2), a. The plate support member 91e is spline-coupled with a primary drive gear 95 that is rotatably supported by the crankshaft 100, and transmits the rotational power of the crankshaft 100 to the transmission 200 via the primary drive gear 95. Yes.

  In the centrifugal multi-plate clutch 91 configured as described above, a clutch lifter lever (not shown) coupled to a change spindle (not shown) rotatably supported by the left and right unit cases 2L and 2R is rotated. As a result, the clutch lifter cam plate 94 rotates. As a result, the clutch lifter cam plate 94 moves to the right side, the connection between the clutch plate 91c and the clutch disc 91d is released, and a neutral state is established. Next, when the gear change is completed, the clutch lifter cam plate 94 is returned to the original position, and the clutch plate 91c and the clutch disc 91d can be connected. When the rotational speed of the crankshaft 100 exceeds a predetermined value, the clutch weight 91f is tilted by centrifugal force, the clutch plate 91c and the clutch disk 91d are connected, and the rotational power of the crankshaft 100 is transmitted to the transmission 200. The

  The transmission 200 includes an input shaft 201 disposed in parallel with the crankshaft 100 and an output shaft 202, and the rotational power input to the primary driven gear 96 attached to the right end portion of the input shaft 201 is transmitted to the output shaft 202. Is transmitted to a drive sprocket 97 attached to the left end of the drive.

  The input shaft 201 is rotatably supported via rolling bearings 72L and 72R disposed in the left and right unit cases 2L and 2R, respectively, and a gear 201a that is integrally formed with the input shaft 201 and an input shaft 201. The right unit case 2R includes a gear 201b to be fitted, and a gear 201c that is engaged with the input shaft 201 so as to be slidable in the axial direction and engageable with the gear 201b by moving a first shift fork (not shown). A primary driven gear 96 to which rotational power is transmitted from the primary drive gear 95 is attached to the right end portion that protrudes to the outside.

  The output shaft 202 is rotatably supported via rolling bearings 73L and 73R disposed in the left and right unit cases 2L and 2R, respectively, and gears 202a and 202b fitted on the output shaft 202, and the gear 202a. , 202b is slidably engaged with the output shaft 202 in the axial direction and engages with the gear 202a or the gear 202b by the movement of a second shift fork (not shown). A drive sprocket 97 that transmits rotational power to the chain 17 is attached to the left end protruding outside the case 2L.

  An oil pump (not shown) driven by the rotational power of the crankshaft 100 is provided on the right side surface of the right unit case 2R, and the lubricating oil supplied from the oil pump is supplied to the right unit case 2R. Is branched into two directions by being pumped to a distribution port (not shown). One of the lubricating oils is fed to a lubricating oil passage 92a formed in the pivot shaft 92 through an oil feeding passage (not shown) formed in the right crankcase cover 52, and lubricates the centrifugal multi-plate clutch 91. Further, the oil is fed to a lubricating oil passage 100a formed in the crankshaft 100 to lubricate the crankshaft 100. Further, as shown in FIGS. 3 and 6, the other branched lubricating oil is a lubricating oil outlet formed in the vicinity of the right end portion of the oil feeding passage (not shown) serving as the insertion hole of the stud bolt 60 and the cam shaft 44. 44a is fed to a lubricating oil passage 44b formed in the camshaft 44, discharged from a discharge hole 44c formed between the two cams 49, 49, and the camshaft 44, rocker arms 46, 46, etc. Lubricate.

  As shown in FIG. 5, the cylinder head 40 is formed with an intake port 47a in which the intake valve 47 is disposed and an exhaust port 48a in which the exhaust valve 48 is disposed, and an injector 99 is assembled to the intake port 47a. ing. The injector 99 is electrically connected to an unillustrated engine control unit, and injects fuel with an optimum high fuel pressure corresponding to the rotational speed into the intake port 47a by an electric signal supplied from the engine control unit. In the drawing, 62 is a stud bolt for attaching the exhaust pipe 18 to the exhaust port 48a.

As shown in FIGS. 4 and 5, the O ₂ sensor 20 is attached between the cooling fins 21 on the right side surface of the cylinder head 40. As shown in FIG. 6, the O ₂ sensor 20 is attached by screwing into a screw hole 22 formed so as to penetrate the exhaust port 48a from the side surface of the cylinder head 40, and the sensor portion 23 is connected to the exhaust port 48a. It arrange | positions so that it may expose in 48a. In the figure, reference numeral 24 denotes a connector for transmitting an electrical signal of the O ₂ sensor 20.

Further, the entire O ₂ sensor 20 is disposed on the inner side in the left-right direction from the side surface of the cylinder head 40. Further, the cooling fin 21 is formed substantially horizontally with respect to the traveling direction, and is divided into two in the front-rear direction by the O ₂ sensor 20. That is, the O ₂ sensor 20 attached to the right side surface of the cylinder head 40 is disposed so as to be embedded in the side surface of the cylinder head 40, and its front and rear and upper sides are surrounded by the cooling fins 21. Protected against foreign objects such as stepping stones.

The O ₂ sensor 20 arranged in this way measures the oxygen concentration in the exhaust gas discharged to the exhaust port 48a, converts the measured oxygen concentration into an electric signal, and transmits it to an engine control unit (not shown). Yes.

As described above, according to the air-cooled internal combustion engine 1 of the present embodiment, the O ₂ sensor 20 is provided between the cooling fins 21, and the cooling fin 21 is divided by the O ₂ sensor 20. since but a function of protecting the O ₂ sensor 20, it is possible to protect the O ₂ sensor 20 from the foreign matter such as stepping stones. In addition, since dedicated parts such as a protective cover for the O ₂ sensor 20 are not required, the assembly of the O ₂ sensor 20 can be improved, and the manufacturing cost can be reduced.

Further, according to the air-cooled internal combustion engine 1 of the present embodiment, the air-cooled internal combustion engine 1 is mounted on the vehicle body frame 11 with the cylinder head 40 forward in the traveling direction and the cylinder substantially horizontal, and the O ₂ sensor 20 is Since it is provided between the cooling fins 21 on the side surface of the cylinder head 40, the O ₂ sensor 20 can be disposed at a position farther from the road surface than when the O ₂ sensor 20 is disposed in the middle of the exhaust pipe. Thereby, the possibility of damage to the O ₂ sensor 20 due to foreign matters such as stepping stones can be greatly reduced.

Further, according to the air-cooled internal combustion engine 1 of the present embodiment, the cooling fin 21 on the side surface of the cylinder head 40 is provided substantially horizontally with respect to the traveling direction, and is divided into two in the front-rear direction by the O ₂ sensor 20. The O ₂ sensor 20 can be protected from foreign matters such as stepping stones, and the turbulence of the air flow in the vicinity of the cooling fin 21 by the O ₂ sensor 20 can be reduced, thereby preventing the air cooling efficiency from being lowered.

Furthermore, according to the air-cooled internal combustion engine 1 of the present embodiment, since the O ₂ sensor 20 is provided between the cooling fins 21 of the cylinder head 40, the O ₂ sensor 20 can be disposed in the vicinity of the combustion chamber 42. Thereby, since the O ₂ sensor 20 can detect the oxygen concentration under the optimum temperature condition, the oxygen concentration in the exhaust gas can be detected with higher accuracy.

In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, in this embodiment, a case has been exemplified for mounting the O ₂ sensor on the right side of the cylinder head, the O ₂ sensor only needs to be attached between the cooling fins of the cylinder head, the mounting position is optional is there.

1 is a side view of a vehicle equipped with an air-cooled internal combustion engine according to the present invention. It is sectional drawing cut | disconnected by the line | wire which connected the cylinder head, cylinder block, crankshaft, main shaft, and countershaft of the power unit explaining the air-cooling type internal combustion engine which concerns on this invention. It is an expanded sectional view of the cylinder head of the power unit shown in FIG. It is the side view which looked at the cylinder head and cylinder block of the power unit shown in FIG. 2 from the right side. It is a longitudinal cross-sectional view of the cylinder head and cylinder block shown in FIG. It is the figure which looked at the cylinder head of the state which removed the cylinder head cover from the front side.

Explanation of symbols

1 Power unit (air-cooled internal combustion engine)
2L Left unit case 2R Right unit case 3 Crank chamber 4 Gear chamber 10 Motorcycle 11 Body frame (vehicle body)
20 O ₂ sensor 21 Cooling fin 22 Screw hole 23 Sensor unit 24 Connector 30 Cylinder block 40 Cylinder head 90 AC generator 91 Centrifugal multi-plate clutch 100 Crankshaft 200 Transmission 201 Input shaft 202 Output shaft

Claims (3)

An air-cooled internal combustion engine provided with an O ₂ sensor for measuring an oxygen concentration in exhaust gas,
Cooling fins are provided in the cylinder head of the internal combustion engine,
The O ₂ sensor is provided between the cooling fins ,
The air-cooling type internal combustion engine , wherein the cooling fin is divided by the O ₂ sensor . The air-cooled internal combustion engine is mounted on a vehicle body with the cylinder head forward in the traveling direction and the cylinder substantially horizontal.
The air-cooled internal combustion engine according to claim 1, wherein the O ₂ sensor is provided between the cooling fins on a side surface of the cylinder head. 3. The air-cooled internal combustion engine according to claim 1, wherein the cooling fin on the side surface of the cylinder head is provided substantially horizontally with respect to a traveling direction, and is divided into two parts in the front-rear direction by the O ₂ sensor. .

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