JP2015045307A - Knock sensor attachment structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knock sensor attachment structure of an internal combustion engine which is reduced in the number of part items and improved in a freedom of arrangement so that a knock sensor is attached to an engine main body by utilizing a temperature sensor.SOLUTION: In a knock sensor of an internal combustion engine, a temperature sensor (70) in which a male screw part (70b), a pivot part (70c) and an attachment work part (70d) are sequentially formed from a temperature detection part (70a) at a tip penetrates a cylindrical shaft part (81) of the knock sensor (80) in which an annular sensor element (83) is externally fit around the cylindrical shaft part (81), the attachment work part (70d) is turned, the male screw part (70b) is screwed into an external sidewall (38r) of an engine main body (Em), the cylindrical shaft part (81) is pivoted by the pivot part (70c), and the knock sensor (80) is jointly fastened.

Description

  The present invention relates to a knock sensor mounting structure for an internal combustion engine.

A knock sensor that detects knocking caused by abnormal combustion in a combustion chamber in an internal combustion engine is a vibration sensor, and is attached to the engine body to detect vibration of the engine body.
In particular, in order to detect knocking with high accuracy, it is generally attached to either a cylinder block or a cylinder head constituting the combustion chamber.
From the cylinder head, the intake pipe extends and intake system auxiliary equipment is arranged, and the exhaust pipe extends, so that interference with the intake system auxiliary equipment is avoided, and the exhaust gas of the exhaust system is A knock sensor is attached at a position where the influence of heat can be avoided (see, for example, Patent Document 1).

JP 2004-301106 A

  In Patent Document 1, in an internal combustion engine in which a cylinder is tilted forward to near horizontal and mounted horizontally in a motorcycle, the cylinder avoids an intake pipe extending upward and an exhaust pipe extending downward from the cylinder head. A structure in which a knock sensor protrudes substantially horizontally on the right side surface of the block is disclosed.

  Since other auxiliary machines and sensors are attached to the engine body of the cylinder block and cylinder head, a knock sensor is provided on the right side surface of the cylinder block that does not interfere with these.

  The internal combustion engine disclosed in Patent Literature 1 is water-cooled, and a water jacket is formed on the cylinder block and the cylinder head. Although not shown, a water temperature sensor may be provided facing the water jacket.

  As described above, when the temperature sensor for detecting the temperature of the internal combustion engine is also attached to the engine body, it is necessary to avoid interference with the knock sensor. The degree of freedom of arrangement becomes small.

  The present invention has been made in view of such points, and the object of the present invention is to reduce the number of parts and improve the degree of freedom of sensor placement by attaching a knock sensor to the engine body using a temperature sensor. It is the point which provides the knock sensor mounting structure of the internal combustion engine which can be figured out.

In order to achieve the above object, the invention according to claim 1
A cylinder block (37) having a cylinder bore (37b) that slidably guides a piston (42) to a crankcase (26) that supports the crankshaft (28), and the piston in the cylinder bore (37b) ( 42) and the top surface of the combustion chamber (43) and the cylinder head (38) in which the intake / exhaust ports (44, 45) are formed are overlapped in sequence with the engine main body (Em) In the knock sensor mounting structure of the internal combustion engine (E) that constitutes
A temperature sensor (70) in which a male screw part (70b), a shaft stopper part (70c), and a mounting work part (70d) are sequentially formed from the temperature detection part (70a) at the tip is arranged around the cylindrical shaft part (81). The engine body portion is rotated by rotating the mounting work portion (70d) through the cylindrical shaft portion (81) of a knock sensor (80) configured by fitting an annular sensor element (83). The male threaded portion (70b) is screwed into the outer wall (38r) of (Em), the cylindrical shaft portion (81) is axially fixed by the axial stop portion (70c), and the knock sensor (80) is fastened together. A knock sensor mounting structure for an internal combustion engine.

The invention according to claim 2 is the knock sensor mounting structure for the internal combustion engine according to claim 1,
The internal combustion engine (E) is an air-cooled internal combustion engine in which cooling fins (37f, 38f) are provided around the engine body (Em),
A sensor mounting boss (68) is formed by cutting out the cooling fins (37f, 38f) in a required portion of the outer wall of the engine body (Em),
The temperature sensor (70) is an oil temperature sensor (70) for detecting the temperature of the lubricating oil, and the male screw part (70b) is screwed into the sensor mounting boss part (68) to thereby knock the knock sensor (80). It is characterized by being attached together.

The invention according to claim 3 is the knock sensor mounting structure for the internal combustion engine according to claim 2,
The internal combustion engine (E) has a cam chain chamber (59) formed on the side of the cylinder bore (37b) of the engine body (Em),
The sensor mounting boss (68) is formed on the side wall (38r) forming the cam chain chamber (59) of the engine body (Em).

According to a fourth aspect of the present invention, in the knock sensor mounting structure for an internal combustion engine according to the third aspect,
The sensor mounting boss (68) is formed on the side wall (38r) near the cylinder bore (37b) of the outer wall forming the cam chain chamber (59) of the engine body (Em),
The screw hole (68h) into which the male screw part (70b) of the temperature sensor (70) of the sensor mounting boss part (68) is screwed is a central axis in a direction in which the outer opening is closer to the cylinder bore (37b) side than the inner opening. (C) is formed to be inclined.

The invention according to claim 5 is the knock sensor mounting structure for the internal combustion engine according to claim 4,
An oil sump (67) is formed in the cam chain chamber (59) along the inner surface of the side wall (38r) where the sensor mounting boss (68) is formed,
The temperature detection part (70a) of the temperature sensor (70) attached to the sensor attachment boss part (68) is inserted into the oil reservoir (67).

The invention according to claim 6 is the knock sensor mounting structure for the internal combustion engine according to claim 4 or 5,
The sensor mounting boss part (68) is formed in the vicinity of the tensioner mounting boss part (37t) of the cam chain tensioner (65) attached to the engine body part (Em),
The attachment working part (70d) of the temperature sensor (70) is located at a position away from the attachment surface (37tm) of the tensioner attachment boss part (37t).

The invention according to claim 7 is the knock sensor mounting structure for the internal combustion engine according to claim 6,
The tensioner mounting boss (37t) is formed on the cylinder block (37),
The sensor mounting boss (68) is formed on the cylinder head (38).

  According to the knock sensor mounting structure of the internal combustion engine according to claim 1, the temperature at which the male screw portion (70b), the shaft stopper portion (70c), and the mounting work portion (70d) are sequentially formed from the temperature detection portion (70a) at the tip. The sensor (70) is mounted through the cylindrical shaft portion (81) of the knock sensor (80) formed by fitting an annular sensor element (83) around the cylindrical shaft portion (81). The working part (70d) is rotated, the male thread part (70b) is screwed into the outer wall (38r) of the engine body part (Em), and the cylindrical shaft part (81) is pivoted by the shaft stopper part (70c). Since the knock sensor (80) is tightened together, the knock sensor (80) and the temperature sensor (70) can be mounted at the same mounting position on the outer wall (38r) of the engine body (Em) at the same time. The number of man-hours can be reduced and the sensor can be easily attached, and the degree of freedom of sensor placement can be improved.

  According to the knock sensor mounting structure of the internal combustion engine according to claim 2, the sensor mounting formed by cutting out the cooling fins (37f, 38f) in the required portion of the outer wall of the engine body (Em) of the air-cooled internal combustion engine. When the oil temperature sensor (70) is screwed into the boss portion (68) with the male screw portion (70b), the knock sensor (80) is fastened together and attached, so the temperature sensor (70) is attached to the knock sensor (80 The sensor mounting boss portion (68) attached together with the cooling fins cut out for the sensor mounting boss portion (68) can be formed by selecting the optimum position of the outer wall of the engine body portion (Em). The cooling effect of the internal combustion engine (E) can be substantially maintained by most of the other cooling fins (37f, 38f).

  According to the knock sensor mounting structure of the internal combustion engine according to claim 3, the sensor mounting is performed on the side wall (38r) forming the cam chain chamber (59) formed on the side of the cylinder bore (37b) of the engine body (Em). Since the boss portion (68) is formed, the knock sensor (80) is attached to the sensor mounting boss portion (68) located away from the combustion chamber (43) and the cylinder bore (37b), and the combustion chamber (43) and the cylinder bore are provided. (37b) is not affected by heat and can detect knocking while maintaining good accuracy, and the oil temperature sensor (70) accurately detects the temperature of the lubricating oil in the cam chain chamber (59). Is possible.

  According to the knock sensor mounting structure for an internal combustion engine according to claim 4, the sensor mounting boss portion (68) is closer to the cylinder bore (37b) in the outer wall forming the cam chain chamber (59) of the engine body portion (Em). The screw hole (68h) formed on the side wall (38r) of the temperature sensor (70) of the sensor mounting boss part (68) is screwed into the screw hole (68h), and the outer opening is closer to the cylinder bore (37b) than the inner opening. Since the central axis (C) is inclined in a direction approaching the temperature sensor, the temperature sensor (70) protruding from the side wall (38r) near the cylinder bore (37b) among the side walls forming the cam chain chamber (59). ) And the knock sensor (80) are provided to be inclined toward the engine main body (Em), so that they do not protrude from the engine main body (Em), and the overall size of the internal combustion engine can be prevented.

  According to the knock sensor mounting structure of the internal combustion engine according to claim 5, the oil sump (67) is placed in the cam chain chamber (59) along the inner surface of the side wall (38r) where the sensor mounting boss portion (68) is formed. The temperature sensor (70a) of the temperature sensor (70) that is formed and attached to the sensor mounting boss (68) is inserted into the oil sump (67), so the temperature sensor (70) requires less oil replacement. By detecting the oil temperature of the oil reservoir (67), the average value of the oil temperature can be detected without being affected by the fluctuation of the oil temperature due to the combustion cycle.

  According to the knock sensor mounting structure of the internal combustion engine according to claim 6, the sensor mounting boss portion (68) of the tensioner mounting boss portion (37t) of the cam chain tensioner (65) attached to the engine main body portion (Em). Since it is formed in the vicinity, the temperature sensor (70) and the cam chain tensioner (65) are located in the vicinity and both protrude from the engine body (Em), so the space around the engine body (Em) can be efficiently used. The temperature sensor (70) mounting work part (70d) is located away from the mounting surface (37tm) of the tensioner mounting boss part (37t). The operation of rotating the working portion (70d) can be performed without being disturbed by the cam chain tensioner (65), and the temperature sensor (70) can be easily attached together with the knock sensor (80), and the workability is good.

According to the knock sensor mounting structure of the internal combustion engine according to claim 7, since the tensioner mounting boss portion (37t) is formed in the cylinder block (37), the cam chain chamber (59) formed in the engine body portion (Em). The cam chain tensioner (65) for applying tension by pressing the cam chain (62) inserted into the cam chain (62) is an optimal position and a mounting space can be easily secured.
Since the sensor mounting boss (68) is formed on the cylinder head (38), it is possible to easily mount the temperature sensor (70) and knock sensor (80) while avoiding interference with the cam chain tensioner (65). In addition, the lubricating oil in the cylinder head (38) can be collected and the temperature of the oil can be easily detected by the temperature sensor (70).

1 is a side view of a motorcycle equipped with an air-cooled internal combustion engine according to an embodiment of the present invention. It is the right view which showed the longitudinal cross section of the center of the air-cooling type internal combustion engine. It is the left view made into the partial cross section of the air-cooling type internal combustion engine. It is the top view which removed the cylinder head cover of the air-cooling type internal combustion engine. It is a fragmentary perspective view of an engine main-body part. It is sectional drawing which shows the attachment structure of an oil temperature sensor and a knock sensor. It is an exploded sectional view for explaining the attachment structure of an oil temperature sensor and a knock sensor.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view of a motorcycle 1 equipped with an internal combustion engine E according to an embodiment to which the present invention is applied.
In the present specification and claims, the front-rear and left-right directions are in accordance with a general standard in which the straight traveling direction of the motorcycle 1 according to the present embodiment is the front.

  The body frame 2 of the motorcycle 1 includes a head pipe 3, a main frame 4 extending obliquely rearward from the head pipe 3, a center frame 5 extending downward from the rear end of the main frame 4, and the head pipe 3. A down frame 6 extending downward from the main frame 4, a seat rail 7 extending rearward from the main frame 4, a mid frame 8 connecting the lower end of the center frame 5 and the center of the seat stay 7, and the down frame 6 and the main frame 4 The reinforcing frame 9 is connected.

A front fork 11 that supports the front wheel 10 is supported by the head pipe 3 so as to be steerable, and a steering handle 12 is connected to the front fork 11.
A rear fork 14 that supports the rear wheel 13 is supported at the lower part of the center frame 5 so as to be swingable up and down.
A cushion unit 15 is provided between the seat rail 7 and the rear fork 14.

The internal combustion engine E is supported by the down frame 6 and the center frame 5 in front of and behind the internal combustion engine E.
The power of the internal combustion engine E is transmitted to the rear wheel 13 via the rear wheel drive chain 17.
A fuel tank 18 is provided on the main frame 4 above the internal combustion engine E, and a tandem seat 19 for a driver and a passenger is mounted on the seat rail 7.
An air-cooled oil cooler 20 is provided in front of the left side of the internal combustion engine E.

The internal combustion engine E is a single-cylinder four-stroke cycle air-cooled internal combustion engine, and a transmission 25 is integrally accommodated in the space behind the left and right split-type crankcases 26L and 26R.
In the internal combustion engine E, a cylinder block 37 and a cylinder head 38 are sequentially stacked on crankcases 26L and 26R that support a crankshaft 28 to constitute an engine body, and a cylinder head cover 39 is further formed on the cylinder head 38. The cylinder stands up in a slightly tilted posture.
On the outer peripheral surfaces of the cylinder block 37 and the cylinder head 38 of the air-cooled internal combustion engine E, a plurality of cooling fins 37f, 38f continuous in the circumferential direction are formed so as to protrude vertically.

Referring to FIG. 2, a piston 42 is slidably fitted in a cylinder bore 37b of a cylinder block 37, and a connecting rod 41 connects a piston pin 42p of the piston 42 and a crank pin 28p of the crankshaft 28 to form a crank mechanism. Is configured.
A combustion chamber 43 is formed on the lower surface of the cylinder head 38 facing the top surface of the piston 42, and the tip of a spark plug (not shown) is mounted from the outside so as to face the combustion chamber 43.

The cylinder head 38 has an intake port 44 extending rearward from the combustion chamber 43 and an exhaust port 45 extending forward from the combustion chamber 43. The intake port 44 and the exhaust port 45 have openings that face the combustion chamber 43. An intake valve 46 and an exhaust valve 47 that open and close are provided.
An intake rocker arm 52 pivotally supported on the intake rocker shaft 50 and an exhaust rocker arm 53 pivotally supported on the exhaust rocker shaft 51 are swung by a camshaft 49 rotatably supported between the cylinder head 38 and the cylinder head cover 39. There is provided a valve mechanism 48 that moves and swings the intake rocker arm 52 and the exhaust rocker arm 53 to operate the intake valve 46 and the exhaust valve 47, respectively.

An intake pipe 54 extends rearward from the intake port 44 of the cylinder head 38, and the intake pipe 54 is connected to an air cleaner 56 via a throttle body 55.
The throttle body 55 is provided with a fuel injection valve 57.
The exhaust pipe 21 extending forward from the exhaust port 45 of the cylinder head 38 is curved downward, wraps around the internal combustion engine E, and is connected to the muffler 22 toward the rear (see FIG. 1).

Referring to FIG. 2, a main shaft 29 of the transmission 25 is disposed behind the crankshaft 28, and a counter shaft 30 of the transmission 25 is disposed further rearward of the main shaft 29. A shift drum 32 is disposed below, a shift fork 33 that is guided by a lead groove of the shift drum 32 and moves a shifter member is provided, and a shift rod 31 is disposed below the counter shaft 30.
The oil pump 34 provided in the crankcase 26 is linked and driven by a crankshaft 28 via a gear, and sucks lubricating oil stored in an oil pan 58 to provide a cylinder head 38 and a main shaft of the transmission. 29 and the countershaft 30 are supplied to the crankshaft 28 through the oil cooler 20.

FIG. 3 is a left side view of the internal combustion engine E with the left crankcase cover removed and the cam chain chamber 59 taken as a cross section.
An AC generator 35 is provided at the left end of the crankshaft 28. FIG. 3 shows a rotor 35r provided at the shaft end of the crankshaft 28 and a stator 35s fixed to the left crankcase cover 27L. It is.
The counter shaft 30 of the transmission is an output shaft, and a rear wheel drive sprocket 17d is provided at the left end of the counter shaft 30, and a rear wheel drive chain 17 is wound around.

  The cam chain chamber 59 is located on the left side of the cylinder bore 37b and extends through the cylinder block 37, the cylinder head 38, and the cylinder head cover 39, and is connected to the cam chain driven sprocket 60 fitted to the left end of the cam shaft 49. A cam chain 62 is passed through the cam chain chamber 59 between the cam chain drive sprocket 61 fitted to the crankshaft 28, and the camshaft 49 is rotationally driven by the rotation of the crankshaft 28.

In the cam chain chamber 59, a longitudinally long front cam chain guide 63 and a rear cam chain guide 64 are provided before and after the cam chain 62.
The vertically long front cam chain guide 63 is fixed to the engine main body by bolts 63b or the like while coming into contact with the longitudinally long portion of the front side of the cam chain 62 from the front.

  The vertically long rear cam chain guide 64 is pivotally supported by a pivot shaft 64p projecting from the rear portion in the cam chain chamber 59 of the cylinder head 38, and is elongated in the vertical direction on the rear side of the cam chain 62. A tensioner rod 65r that protrudes from the tensioner body 65a of the cam chain tensioner 65 that is suspended from the rear portion and is attached to the rear side wall that forms the cam chain chamber 59 of the cylinder block 37 presses the rear cam chain guide 64 from the rear. As a result, the rear cam chain guide 64 is pressed against the rear side of the cam chain 62 and applies tension to the cam chain 62.

Referring to FIGS. 3 and 5, a tensioner mounting boss portion 37t is formed on the rear side wall forming the left cam chain chamber 59 of the cylinder block 37 so as to protrude from the cutout portion of the cooling fin 37f.
The tensioner mounting boss portion 37t is formed with a mounting hole for fitting the tensioner main body portion 65a in the center so as to penetrate the side wall.
The cam chain tensioner 65 has a mounting flange portion extending symmetrically from the tensioner main body 65a by fitting the tensioner main body 65a into the mounting hole through the tensioner rod 65r from the outside through the mounting hole of the tensioner mounting boss 37t. The cam chain tensioner 65 is attached to the tensioner attachment boss part 37t by abutting 65f, 65f on the attachment surface 37tm of the tensioner attachment boss part 37t and fastening with the bolts 66, 66.

Referring to FIG. 3, a cam chain chamber 59 is formed below a pivot shaft 64p that protrudes from the rear portion of the cam chain chamber 59 of the cylinder head 38 and pivotally supports the upper end of the rear cam chain guide 64. An oil sump 67 that is recessed downward is formed along the inner surface of the rear side wall 38r in the outer side wall.
The oil reservoir 67 is a place where droplets of oil that has been supplied to the cylinder head 38 by the oil pump 34 and lubricated the cam shaft 49 and the like as the cam chain 62 rotates are accumulated.

Of the cooling fins 38f formed on the outer peripheral surface of the cylinder head 38 so as to protrude in a flange shape, a cylindrical portion is formed in the fin deficient space 38fs formed by cutting out a part of the cooling fin 38f on the rear side wall 38r of the oil reservoir 67. A sensor mounting boss portion 68 is formed so as to protrude obliquely rearward and to the right (see FIGS. 3, 4 and 5).
The sensor mounting boss 68 is formed with a screw hole 68h in which a female screw is partially engraved so as to pass through the rear side wall 38r (see FIG. 7), and the inner opening of the screw hole 68h faces the oil reservoir 67, The outer opening is biased in a direction (rightward) closer to the cylinder bore 37b side than the inner opening, and the central axis C of the screw hole 68h is inclined obliquely rearward and rightward (see FIG. 4).

  Referring to FIG. 4, the central axis C of the screw hole 44 h drilled in the joint end surface where the intake pipe 54 is joined at the opening end of the intake port 44 and the central axis C of the screw hole 68 h of the sensor mounting boss portion 68. Are parallel to each other and improve the workability of the screw holes by sharing the drilling direction of the screw holes.

A knock sensor 80 is attached to the sensor mounting boss 68 together with the oil temperature sensor 70.
As shown in FIG. 7, the oil temperature sensor 70 has a generally rod-like shape in which the male screw portion 70b, the shaft stopper portion 70c, and the mounting work portion 70d are sequentially coaxially arranged from the tip temperature detection portion 70a to the base connector portion 70e. It is a sensor that makes.
The temperature detector 70a has a bottomed cylindrical shape with a small diameter, the male screw 70b has a slightly larger outer diameter than the temperature detector 70a, and the shaft stopper 70c is a long cylindrical portion having the same diameter as the male screw 70b. Yes, the mounting work portion 70d has a nut shape expanded in the radial direction, that is, a flat hexagonal column shape, and the connector portion 70e has a cylindrical shape.

On the other hand, in the knock sensor 80, an annular piezoelectric element 83 is sandwiched between a pair of electrodes 84, 84 around a cylindrical shaft portion 81 and is inserted together with an annular weight 86. A part of the annular resin case 82 extends in a diagonal cylindrical shape in the oblique radial direction to form a connector portion 82e (see FIG. 7).
The cylindrical shaft portion 81 has an inner diameter slightly larger than the outer diameter of the shaft stop portion 70c of the oil temperature sensor 70, a shaft length slightly shorter than the shaft stop portion 70c of the oil temperature sensor 70, and a flange portion 81f formed at one end. ing.

The annular piezoelectric element 83 and the weight 86 are fitted on the outer periphery of the cylindrical shaft portion 81 between the flange portion 81 f of the cylindrical shaft portion 81 and the reduced diameter portion of the resin case 82.
A signal line 85 extends from the pair of electrodes 84 and 84 sandwiching the piezoelectric element 83 to the terminal of the connector portion 82e.
The knock sensor 80 is configured as described above, and detects the state of vibration from the pressure applied to the piezoelectric element 83 by the behavior of the weight 86.

  The temperature detecting portion 70a and male screw portion 70b of the oil temperature sensor 70 are passed through the cylindrical shaft portion 81 of the knock sensor 80, and the washer 75 is sandwiched between the mounting work portion 70d and the knock sensor 80 is attached to the oil temperature sensor. 70 is inserted into the screw hole 68h of the sensor mounting boss 68, and the temperature detecting portion 70a and the male screw portion 70b of the oil temperature sensor 70 protruding from the cylindrical shaft portion 81 of the knock sensor 80 are inserted into the screw holes 68h of the sensor mounting boss portion 68. The male screw portion 70b is screwed into the female screw of the screw hole 68h, and the hexagonal column-shaped mounting work portion 70d is rotated by a spanner or the like, and the oil temperature sensor 70 is screwed into the screw hole 68h of the sensor mounting boss portion 68 and tightened. Attach the knock sensor 80 together.

The temperature sensor 70a of the oil temperature sensor 70 is inserted into the oil reservoir 67, the connector 82e of the knock sensor 80 faces upward, the knock sensor 80 is fastened together with the oil temperature sensor 70, and the oil temperature sensor 70 itself protrudes rearward and diagonally right along the central axis C of the screw hole 68h of the sensor mounting boss 68.
Therefore, the knock sensor 80 together with the oil temperature sensor 70 can be simultaneously mounted on the sensor mounting boss portion 68 of the rear side wall 38r forming the cam chain chamber 59 of the cylinder head 38, and can be easily mounted with a reduced number of parts and mounting steps. It is possible to improve the degree of freedom of sensor placement.

  Since the sensor mounting boss 68 is formed on the rear side wall 38r forming the cam chain chamber 59 formed on the side of the cylinder bore 37b of the engine main body Em, the sensor mounting boss positioned away from the combustion chamber 43 and the cylinder bore 37b. A knock sensor 80 is attached to the portion 68, so that knocking can be detected while maintaining good accuracy without being affected by the heat of the combustion chamber 43 and the cylinder bore 37b, and an oil reservoir 67 in the cam chain chamber 59 can be detected. The oil temperature sensor 70 can accurately detect the temperature of the accumulated lubricating oil.

  The temperature detection unit 70a of the oil temperature sensor 70 is inserted into the oil reservoir 67 and is positioned at an appropriately higher position than the bottom surface of the oil reservoir 67. Even when foreign matter is accumulated in the oil reservoir 67, the temperature detection unit 70a The detection accuracy of the oil temperature sensor 70 is kept good without touching the foreign matter.

Since the oil sump 67 is located at the rear of the cylinder head 38 and the cylinder is tilted forward, less oil flows down to the oil sump 67.
For this reason, since the oil in the oil reservoir 67 is hardly replaced, the average value of the oil temperature can be detected without being affected by the fluctuation of the oil temperature due to the combustion cycle.
Since the oil reservoir 67 is provided integrally with the cylinder head 38 constituting the combustion chamber 43, the oil in the oil reservoir 67 fluctuates following the temperature of the combustion chamber 43, and the temperature can be detected with higher accuracy.
Further, since the oil reservoir 67 and the oil temperature sensor 70 are provided at positions away from the exhaust port 45, they are less affected by the exhaust heat and can detect the oil temperature with high accuracy.

  Since the oil temperature sensor 70 is attached together with the knock sensor 80 to the sensor mounting boss 68 formed by cutting out the cooling fin 38f on the outer wall of the cylinder head 38, as described above, the oil temperature sensor 70 The sensor mounting boss portion 68 can be formed by selecting the rear side wall 38r of the cam chain chamber 59 of the cylinder head 38 suitable for detection by the knock sensor 80 and the cooling notched for the sensor mounting boss portion 68. The fin is a part, and the cooling effect of the internal combustion engine E can be substantially maintained by most of the other cooling fins 38f.

  The sensor mounting boss portion 68 is formed on the rear side wall 38r near the cylinder bore 37b in the outer wall forming the cam chain chamber 59 of the engine body Em, and the male screw portion 70b of the oil temperature sensor 70 in the sensor mounting boss portion 68 is screwed. The screw hole 68h to be joined is formed with the central axis C inclined so that the outer opening is closer to the cylinder bore (37b) than the inner opening, so that the oil temperature protruding from the rear side wall 38r of the cam chain chamber 59 is increased. A sensor 70 and a knock sensor 80 are provided to be inclined toward the engine main body Em side (right side) along the central axis C.

That is, the oil temperature sensor 70 and the knock sensor 80 protrude to the rear of the left side portion where the cam chain chamber 59 of the cylinder head 37 is located, and protrude to the right so as not to protrude from the left side surface of the cylinder head 37. Therefore, it is possible to prevent the entire internal combustion engine from becoming large.
Further, since the oil temperature sensor 70 and the knock sensor 80 are provided so as to be hidden behind the cylinder head 37, they are protected from flying stones and the like.

  A sensor mounting boss 68 to which the oil temperature sensor 70 and the knock sensor 80 are mounted is formed on the rear side wall 38r of the cam chain chamber 59 on the left side portion of the cylinder head, and a tensioner mounting boss 37t to which the cam chain tensioner 65 is mounted. Formed on the rear side wall of the cam chain chamber 59 on the left side of the cylinder block 37, and the sensor mounting boss 68 and the tensioner mounting boss 37t are formed at positions close to each other, so that the oil temperature sensor 70 and the cam chain tensioner 65 are Protruding in the vicinity of each other, the space around the engine body Em can be used efficiently, and the mounting portion 70d of the oil temperature sensor 70 is separated rearward (outward) from the mounting surface 37tm of the tensioner mounting boss portion 37t. Therefore, the operation of rotating the mounting portion 70d of the oil temperature sensor 70 is performed without being interrupted by the cam chain tensioner 65, and the oil temperature sensor 70 is turned off. Kusensa can be easily be mounted together with 80, workability is good.

Since the tensioner mounting boss 37t is formed in the cylinder block 37, the tensioner mounting boss 37t presses the cam chain 62 inserted into the cam chain chamber 59 formed in the engine main body Em to apply tension. It is the optimum position for attaching the chain tensioner 65 and the installation space can be easily secured.
Since the sensor mounting boss portion 68 is formed on the cylinder head 38, the oil temperature sensor 70 and the knock sensor 80 can be easily mounted while avoiding interference with the cam chain tensioner 65, and lubrication within the cylinder head 38 is possible. The oil temperature can be easily collected and the oil temperature sensor 70 can detect the oil temperature.

E ... Internal combustion engine, Em ... Engine body, 25 ... Transmission, 26L, 26R ... Crankcase, 37 ... Cylinder block, 37b ... Cylinder bore, 37t ... Tensioner mounting boss, 37f ... Cooling fin, 38 ... Cylinder head, 38r ... rear side wall, 38f ... cooling fin, 39 ... cylinder head cover, 48 ... valve operating mechanism, 49 ... camshaft, 59 ... cam chain chamber, 62 ... cam chain, 63 ... front cam chain guide, 64 ... rear cam chain guide , 65 ... Cam chain tensioner, 67 ... Oil reservoir, 68 ... Sensor mounting boss,
70 ... Oil temperature sensor, 70a ... Temperature detection part, 70b ... Male screw part, 70c ... Shaft stop part, 70d ... Installation work part, 70e ... Connector part, 75 ... Washer,
80 ... knock sensor, 81 ... cylindrical shaft part, 82 ... resin case, 83 ... piezoelectric element, 85 ... signal line, 86 ... weight.

Claims (7)

A cylinder block (37) having a cylinder bore (37b) that slidably guides a piston (42) to a crankcase (26) that supports the crankshaft (28), and the piston in the cylinder bore (37b) ( 42) and the top surface of the combustion chamber (43) and the cylinder head (38) in which the intake / exhaust ports (44, 45) are formed are overlapped in sequence with the engine main body (Em) In the knock sensor mounting structure of the internal combustion engine (E) that constitutes
A temperature sensor (70) in which a male screw part (70b), a shaft stopper part (70c), and a mounting work part (70d) are sequentially formed from the temperature detection part (70a) at the tip is arranged around the cylindrical shaft part (81). The engine body portion is rotated by rotating the mounting work portion (70d) through the cylindrical shaft portion (81) of a knock sensor (80) configured by fitting an annular sensor element (83). The male threaded portion (70b) is screwed into the outer wall (38r) of (Em), the cylindrical shaft portion (81) is axially fixed by the axial stop portion (70c), and the knock sensor (80) is fastened together. A knock sensor mounting structure for an internal combustion engine. The internal combustion engine (E) is an air-cooled internal combustion engine in which cooling fins (37f, 38f) are provided around the engine body (Em),
A sensor mounting boss (68) is formed by cutting out the cooling fins (37f, 38f) in a required portion of the outer wall of the engine body (Em),
The temperature sensor (70) is an oil temperature sensor (70) for detecting the temperature of the lubricating oil, and the male screw part (70b) is screwed into the sensor mounting boss part (68) to thereby knock the knock sensor (80). The knock sensor mounting structure for an internal combustion engine according to claim 1, wherein the two are fastened together. The internal combustion engine (E) has a cam chain chamber (59) formed on the side of the cylinder bore (37b) of the engine body (Em),
The knock sensor for an internal combustion engine according to claim 2, wherein the sensor mounting boss (68) is formed on a side wall (38r) forming the cam chain chamber (59) of the engine body (Em). Mounting structure. The sensor mounting boss (68) is formed on the side wall (38r) near the cylinder bore (37b) of the outer wall forming the cam chain chamber (59) of the engine body (Em),
The screw hole (68h) into which the male screw part (70b) of the temperature sensor (70) of the sensor mounting boss part (68) is screwed is a central axis in a direction in which the outer opening is closer to the cylinder bore (37b) side than the inner opening. 4. The knock sensor mounting structure for an internal combustion engine according to claim 3, wherein (C) is inclined. An oil sump (67) is formed in the cam chain chamber (59) along the inner surface of the side wall (38r) where the sensor mounting boss (68) is formed,
The internal combustion engine according to claim 4, wherein the temperature detection part (70a) of the temperature sensor (70) attached to the sensor attachment boss part (68) is inserted into the oil reservoir (67). Knock sensor mounting structure. The sensor mounting boss part (68) is formed in the vicinity of the tensioner mounting boss part (37t) of the cam chain tensioner (65) attached to the engine body part (Em),
The attachment work part (70d) of the temperature sensor (70) is located at a position away from the attachment surface (37tm) of the tensioner attachment boss part (37t). 5. A knock sensor mounting structure for an internal combustion engine according to claim 5. The tensioner mounting boss (37t) is formed on the cylinder block (37),
The knock sensor mounting structure for an internal combustion engine according to claim 6, wherein the sensor mounting boss (68) is formed in the cylinder head (38).

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