JP2009013835A - Air-cooled engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air-cooled engine capable of improving detecting accuracy of an oil temperature inside a cylinder head by suppressing the effect of circulation of engine oil. <P>SOLUTION: The air-cooled engine is equipped with an oil jacket 47 that is a flow passage of the engine oil to a valve train mechanism 30 in the cylinder head 27. An oil reservoir 51 is formed to be recessed for retaining the engine oil in a wall part of the oil jacket 47, and an oil temperature sensor 55 is mounted on the cylinder head 27 for detecting the oil temperature inside the oil reservoir 51. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air-cooled engine suitable for adopting an electronically controlled fuel injection device.

Conventionally, in the above-described air-cooled engine, the cylinder part is projected substantially horizontally from the crankcase, and an oil temperature sensor is attached to the lower part of the cylinder head to detect the oil temperature in the cylinder head of the cylinder part. (For example, refer to Patent Document 1).
JP 2006-257929 A

By the way, since the engine oil constantly circulates inside the engine including the inside of the cylinder head during engine operation, in the above-described conventional configuration, the oil temperature on the flow path when the engine oil in the cylinder head returns into the crankcase. Therefore, the flow of the engine oil may affect the detection accuracy of the oil temperature sensor.
Therefore, the present invention provides an air-cooled engine that can suppress the influence of engine oil circulation and improve the detection accuracy of the oil temperature in the cylinder head.

  As a means for solving the above-mentioned problems, the invention described in claim 1 includes a crankcase (for example, the crankcase 21 of the embodiment) for rotatably supporting a crankshaft (for example, the crankshaft 22 of the embodiment), and the crankshaft. A cylinder portion (for example, the embodiment) having a cylinder bore (for example, the cylinder bore 26a of the embodiment) for slidably fitting a connected piston (for example, the piston 26b of the embodiment) and forming a fuel chamber for facing the top of the piston. Cylinder portions 23, 123), and the cylinder portion is coupled to the cylinder body (for example, the cylinder body 26 of the embodiment) that forms the cylinder bore, and the valve mechanism (for example, the embodiment of the embodiment). Cylinder head (for example, the cylinder head of the embodiment) that supports the valve operating mechanisms 30 and 130) 7, 127) an air-cooled engine (for example, the engine 20 or 120 of the embodiment), and an oil jacket (for example, the oil jacket of the embodiment) serving as a flow path for engine oil to the valve mechanism in the cylinder head. 47, 147), an oil sump (for example, oil sump 51, 151 of the embodiment) for retaining the engine oil is provided in a part of the oil jacket, and the oil temperature in the oil sump is detected to detect the oil temperature in the oil sump. An oil temperature sensor (for example, the oil temperature sensor 55 of the embodiment) is attached to the cylinder head.

  The invention described in claim 2 includes a fuel injection valve (for example, the injector 24c of the embodiment) whose fuel injection amount is controlled based on a detection value of the oil temperature sensor.

  According to a third aspect of the present invention, the oil temperature sensor is adjacent to an intake system component (for example, the throttle body 24 of the embodiment) connected to an intake port (for example, the intake ports 35 and 135 of the embodiment) of the cylinder head. It is characterized by being arranged.

  According to a fourth aspect of the present invention, the cylinder head covers a wall portion (for example, the rib 53 of the embodiment) that covers the operated portion (for example, the main body portion 56 of the embodiment) of the oil temperature sensor from the side opposite to the intake system component. ), And the wall portion is disposed adjacent to the mounting portion of the oil temperature sensor (for example, the mounting boss 52 of the embodiment).

  According to a fifth aspect of the present invention, the cylinder portion is provided to be inclined with respect to the vertical direction, and a transmission mechanism (for example, the transmission mechanism 40 of the embodiment) that transmits the power of the crankshaft to the valve mechanism. A transmission mechanism accommodating chamber (for example, the transmission mechanism accommodating chamber 41 of the embodiment) that communicates between the inside of the crankcase and the cylinder head to accommodate the oil reservoir, and the oil reservoir is a cylinder axis (for example, the embodiment) in the oil jacket. The cylinder axis C2) is arranged on the side opposite to the transmission mechanism accommodation chamber.

  According to the invention described in claim 1, by detecting the oil temperature in the oil reservoir in the oil jacket in the cylinder head, the influence of the circulation of the engine oil on the oil temperature detection is suppressed, and the oil temperature in the cylinder head The detection accuracy of the engine temperature of the air-cooled engine can be improved.

  According to the second aspect of the present invention, the fuel injection amount from the fuel injection valve can be more accurately controlled, and the fuel efficiency and exhaust gas performance of the air-cooled engine can be improved.

  According to the third aspect of the invention, one side of the oil temperature sensor is covered with the intake system components, and the influence of the engine exhaust heat on the detection value of the oil temperature sensor can be suppressed.

  According to the invention described in claim 4, after the oil temperature sensor and the intake system parts are assembled to the cylinder head, it becomes difficult to access the oil temperature sensor, and erroneous operation such as removing the oil temperature sensor and mischief are prevented. it can.

  According to the fifth aspect of the present invention, the engine oil in the cylinder head is difficult to collect, and the oil is disposed in a portion that is also separated from the transmission mechanism housing chamber that serves as a return path for the engine oil from the cylinder head to the crankcase. Since the reservoir is disposed, it is possible to further improve the oil temperature detection accuracy by suppressing the entry and exit of the engine oil in the oil reservoir.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the directions such as front, rear, left and right in the following description are the same as those in the vehicle unless otherwise specified. In the figure, the arrow FR indicates the front of the vehicle, the arrow LH indicates the left side of the vehicle, and the arrow UP indicates the upper side of the vehicle.

In the motorcycle (saddle-type vehicle) 1 shown in FIG. 1, the front wheel 2 is pivotally supported by the lower ends of the left and right front forks 3, and the upper portions of the left and right front forks 3 are connected to the head pipe of the vehicle body frame 5 via the steering stem 4. 6 is pivotally supported to be steerable.
The vehicle body frame 5 includes a main frame portion 7 that extends rearward from the upper portion of the head pipe 6 and then bends downward, and a down frame portion 8 that extends downward from the lower portion of the head pipe 6 and bends rearward. It is set as the cradle type | mold connected with the pivot part 9.

A pivot 9 pivotally supports the front end of a swing arm 11 so that it can swing up and down. A rear wheel 12 of the motorcycle 1 is pivotally supported at the rear end of the swing arm 11. A rear cushion unit 13 is disposed between the front part of the swing arm 11 and the rear part of the vehicle body frame 5.
An engine (internal combustion engine) 20 that is a prime mover of the motorcycle 1 is mounted inside the body frame 5.

  In the figure, reference numeral 14 denotes a steering handle attached to the steering stem 4, reference numeral 15 denotes a fuel tank disposed on the main frame portion 7, and reference numeral 16 denotes a saddle riding disposed behind the fuel tank 15. Reference numeral 17 denotes a seat frame continuously provided behind the vehicle body frame 5 to support the saddle riding seat 16, reference numeral 18 denotes a step holder attached to the rear of the pivot portion 9, and reference numeral 19 denotes an exhaust pipe 25. Each silencer to which the rear end is connected is shown.

  The engine 20 is an air-cooled single-cylinder engine. A crankshaft 22 having a rotation center axis (crank axis) C1 in the left-right direction (vehicle width direction) is disposed in the crankcase 21. The cylinder portion 23 is erected substantially vertically (specifically, in a slightly forward tilted posture). An axis line (cylinder axis line, that is, the central axis line of the cylinder bore 26a) C2 along the standing direction of the cylinder part 23 is inclined with respect to the vertical direction so that the upper part thereof is located on the front side. A throttle body 24 that is an engine intake system component is connected to the rear side of the cylinder portion 23, and the exhaust pipe 25 that is an engine exhaust system component is connected to the front side of the cylinder portion 23.

  The motorcycle 1 employs an electronically controlled fuel injection device for the fuel supply system of the engine 20. That is, the electronic control unit (not shown) that controls the operation of the engine 20 receives various information related to the opening degree of the throttle valve and the operating state of the engine 20, and the electronic control unit controls ignition of the engine 20 and the fuel. Injection control or the like is performed. Detection information from an oil temperature sensor 55 described later is input to the electronic control unit as engine temperature information.

  The cylinder part 23 mainly includes a cylinder main body 26 provided integrally with the crankcase 21, a cylinder head 27 attached on the cylinder main body 26, and a head cover 28 attached on the cylinder head 27. A piston 26 b is slidably fitted in the cylinder bore 26 a of the cylinder body 26, and a combustion chamber is formed between the top of the piston 26 b and the cylinder head 27. Due to the combustion of the mixture of fuel and outside air in the combustion chamber, the piston 26b reciprocates in the cylinder bore 26a, and the reciprocation is converted into rotational movement of the crankshaft 22 via the connecting rod.

  As shown in FIG. 2, in the cylinder head 27, a valve mechanism 30 mainly including intake and exhaust camshafts 31 and 32 and intake and exhaust valves 33 and 34 parallel to the crank axis C1 is disposed. The camshafts 31 and 32 are linked and driven with the crankshaft 22 via a chain type or gear train type transmission mechanism 40 (see FIG. 3). In addition, the code | symbol C3, C4 in a figure shows the rotation center axis line of each camshaft 31 and 32, respectively.

Intake and exhaust ports 35 and 36 are formed in the rear part and the front part of the cylinder head 27, and the combustion chamber side openings of these ports 35 and 36 are opened and closed by the intake and exhaust valves 33 and 34, respectively.
Referring also to FIG. 1, an intake passage 24a connected to the intake port 35 is formed in the throttle body 24, and the intake passage 24a is opened and closed by a butterfly throttle valve. The throttle body 24 is attached with an injector 24c that injects fuel into the intake passage 24a under the control of the electronic control unit.

  Engine oil is stored in the lower part of the crankcase 21 (in the oil pan), and the engine oil is pumped to each part of the engine by the operation of an oil pump (not shown) that is driven in linkage with the crankcase 21. Thereby, the engine oil is used for lubrication of each part in the engine, and also acts on airtightness, cooling, buffering, and the like.

The engine oil supplied to the valve operating mechanism 30 is supplied from the oil pump to the cylinder head 27, and the engine oil is supplied to the sliding portions through the hollow portions in the camshafts 31 and 32. Is done.
Referring also to FIG. 3, the engine oil supplied to the valve mechanism 30 is returned to the crankcase 21 through a transmission mechanism housing chamber 41 that houses the transmission mechanism 40 on the right side of the cylinder portion 23. The engine oil returned into the crankcase 21 is appropriately circulated in the engine by the operation of the oil pump.

  A valve chamber 42 formed with the head cover 28 in the upper part of the cylinder head 27 is an oil chamber that communicates with the inside of the crankcase 21 via a transmission mechanism accommodating chamber 41. A pair of left and right intake side bolt insertion holes 43 and a bolt seat surface 43a for fixing bolts for fixing the cylinder head 27 and the cylinder body 26 to the crankcase 21 are formed below the intake side camshaft 31 in the cylinder head 27. Below the exhaust side camshaft 32 in the cylinder head 27, a pair of left and right exhaust side bolt insertion holes 44 and a bolt seat surface 44a for the fixing bolt are formed. 2 and 3, reference numeral 28a denotes an attachment boss for attaching the head cover 28 to the cylinder head 27, and reference numeral 28b denotes a bolt hole formed in the attachment boss 28a along the cylinder axis C2.

  Between the left and right intake-side bolt seat surfaces 43a, the upper ends of a pair of left and right intake-side valve guides 45 that pass through the stem of the intake valve 33 are located, and between the left and right exhaust-side bolt seat surfaces 44a, the exhaust The upper ends of a pair of left and right exhaust side valve guides 46 that pass through the stem of the valve 34 are located. That is, the engine 20 is a four-valve type.

  Here, a portion of the valve operating chamber 42 located below the camshafts 31 and 32 is recessed downward (in the crankcase 21 side) with respect to the periphery of the bearing portion of the camshafts 31 and 32 (the depth is increased). ) Intake and exhaust side oil jackets 47 and 48 are provided.

  The bolt seat surfaces 43a and 44a are formed on the bottom wall portions of the oil jackets 47 and 48, and the upper end portions of the valve guides 45 and 46 are disposed in the vicinity of the bolt seat surfaces 43a and 44a. . The right end portions of the oil jackets 47 and 48 are opened in the transmission mechanism accommodating chamber 41, and the engine oil supplied to the valve operating mechanism 30 is dropped into the oil jackets 47 and 48, and then the transmission mechanism from the right end portion. It reaches into the storage chamber 41 and is returned into the crankcase 21.

  The front wall portion of the intake side oil jacket 47 and the rear wall portion of the exhaust side oil jacket 48 are separated from each other with the cylinder axis C2 therebetween. The space between the oil jackets 47 and 48 is a plug hole 49b for attaching / detaching the spark plug (see FIG. 2). The plug hole 49b opens to the left of the cylinder portion 23 (on the side opposite to the transmission mechanism accommodating chamber 41). It is also a jacket. In FIG. 3, reference numerals 49 and 49a denote a plug mounting hole and a plug seat surface that are substantially coaxial with the cylinder axis C2.

  An oil sump 51 that is recessed downward along the cylinder axis C2 is located at a portion immediately behind the bolt seat surface 43a on the left side (opposite to the transmission mechanism accommodation chamber 41) of the bottom wall portion of the intake side oil jacket 47. Is formed. The oil sump 51 has a rectangular parallelepiped shape with a narrow front-rear width, and the oil temperature sensor 55 that detects the temperature of the engine oil in the cylinder head 27 is provided so that the detection unit 57 faces the oil sump 51. .

  An attachment boss 28a for attaching the head cover 28 to the cylinder head 27 is positioned above the oil sump 51 (see FIG. 3), and the attachment boss 28a is in the direction of the arrow along the cylinder axis 23 and It is provided so as to overlap a part (so as to cover a part of the oil reservoir 51 from above).

  The oil temperature sensor 55 has a configuration in which a rod-shaped detection portion 57 protrudes coaxially from the lower neck end of the bolt-shaped main body portion 56 and a wiring connection coupler 58 protrudes from the head portion of the main body portion 56. The central axis (sensor axis) C5 is arranged to be orthogonal to the cylinder axis C2 and the left-right direction. The oil temperature sensor 55 is attached to and detached from the cylinder head 27 by attaching a tool to the head of the main body 56 and rotating it around the axis C5.

  Referring also to FIG. 4, a mounting boss 52 for the oil temperature sensor 55 projects rearward at a portion on the left side of the cylinder outer opening of the intake port 35 in the rear wall portion (intake side wall portion) of the cylinder head 27. To be formed. The mounting boss 52 is located immediately behind the oil sump 51, and the detecting portion 57 of the oil temperature sensor 55 and the neck of the main body portion 56 are inserted into the mounting boss 52 from behind, and the detecting portion 57 of the oil temperature sensor 55 is inserted into the oil boss 52. The oil temperature sensor 55 is fixed to the cylinder head 27 by being inserted into the reservoir 51 and screwing the bottom of the main body 56 to the inner periphery of the mounting boss 52.

  In the portion of the cylinder head 27 on the left side of the mounting boss 52 (the portion on the side opposite to the intake port 35 and the throttle body 24), the head of the body portion 56 that is the operated portion of the oil temperature sensor 55 is viewed from the left. A covering rib 53 is provided. The rib 53 has an arc shape centered on the axis C5 as viewed along the sensor axis C5, and is provided adjacent to the left side of the mounting boss 52.

  Here, in the forward tilted cylinder portion 23 (cylinder head 27), the portion on the upper side (intake side) of the cylinder axis C2 is lower than the portion on the lower side (exhaust side) of the cylinder axis C2. The engine oil circulating inside is difficult to collect and its flow rate is low. That is, by providing the oil reservoir 51 on the intake side, which is the upper side of the cylinder portion 23 in the forward inclined posture, the engine oil in and out of the oil reservoir 51 can be relatively reduced. By detecting the oil temperature in the oil reservoir 51 with the oil temperature sensor 55, it is possible to detect the oil temperature with high accuracy while suppressing the fluctuation of the oil temperature due to the circulation of the engine oil.

  Further, since the oil temperature sensor 55 is disposed adjacent to the left side of the cylinder outside opening of the intake port 35, the influence of the engine exhaust heat on the oil temperature sensor 55 is suppressed, and the oil temperature detection accuracy is further enhanced, and the oil temperature sensor 55 is further improved. The temperature sensor 55 is adjacent to the throttle body 24 (overlaps when viewed from the side of the engine), so that parts such as a cover for the oil temperature sensor 55 can be simplified.

  As described above, the air-cooled engine 20 in the above embodiment includes the crankcase 21 that rotatably supports the crankshaft 22 and the cylinder bore 26a that slidably fits the piston 26b connected to the crankshaft 22. And a cylinder part 23 that forms a fuel chamber that faces the top of the piston 26b. The cylinder part 23 is coupled to the cylinder body 26 and the valve body 26. The cylinder body 26 forms the cylinder bore 26a. A cylinder head 27 that supports the mechanism 30 is provided with an oil jacket 47 serving as a flow path of engine oil for the valve mechanism 30 in the cylinder head 27, and a wall portion of the oil jacket 47 is provided. When the oil reservoir 51 for retaining the engine oil is recessed The one in which the oil temperature sensor 55 is attached to the cylinder head 27 so as to detect the oil temperature in the oil reservoir 51.

  According to this configuration, by detecting the oil temperature in the oil reservoir 51 in the oil jacket 47 in the cylinder head 27, the influence of the circulation of the engine oil on the oil temperature detection is suppressed, and the oil temperature in the cylinder head 27 The detection accuracy of the engine temperature of the air-cooled engine 20 can be improved.

  Further, the air-cooled engine 20 includes the injector 24c whose fuel injection amount is controlled based on the detection value of the oil temperature sensor 55, so that the fuel injection amount from the injector 24c can be controlled more accurately, and the air-cooled engine 20 fuel consumption and exhaust gas performance can be improved.

  Further, in the air-cooled engine 20, the oil temperature sensor 55 is disposed adjacent to the throttle body 24 connected to the intake port 35 of the cylinder head 27, so that one side of the oil temperature sensor 55 is connected to the throttle body. 24 and the influence of the engine exhaust heat on the detection value of the oil temperature sensor 55 can be suppressed.

  In the air-cooled engine 20, the cylinder head 27 has a rib 53 that covers the main body 56 of the oil temperature sensor 55 from the side opposite to the throttle body 24, and the rib 53 is attached to the oil temperature sensor 55. Since the oil temperature sensor 55 and the throttle body 24 are assembled to the cylinder head 27 by being arranged adjacent to the boss 52, it becomes difficult to access the oil temperature sensor 55, and the oil temperature sensor 55 is removed. Misoperation and mischief can be prevented.

  Furthermore, in the air-cooled engine 20, the cylinder portion 23 is provided so as to be inclined with respect to the vertical direction, and the transmission mechanism 40 for transmitting the power of the crankshaft 22 to the valve mechanism 30 is accommodated. A transmission mechanism accommodating chamber 41 that communicates the inside of the crankcase 21 and the cylinder head 27 is provided, and the oil reservoir 51 is located above the cylinder axis C2 in the oil jacket 47 and opposite to the transmission mechanism accommodating chamber 41. Therefore, the engine oil in the cylinder head 27 is difficult to collect, and the oil is located in a part away from the transmission mechanism housing chamber 41 that serves as a return path for the engine oil from the cylinder head 27 to the crankcase 21. The reservoir 51 is arranged, and the oil temperature is detected by suppressing the engine oil in and out of the reservoir 51. Degree can be further improved.

Next, a second embodiment of the present invention will be described with reference to FIGS.
The air-cooled engine 120 of this embodiment has an OHC two-valve type valve mechanism 130 with respect to that of the first embodiment, and a cam chain chamber (transmission mechanism accommodation chamber) 141 on the left side of the cylinder portion 123. However, the main difference is that an oil reservoir 151 is provided on the upper side (intake side) and the left side (cam chain chamber 141 side) of the cylinder axis C2 of the cylinder portion 123 in the forward inclined posture. Are denoted by the same reference numerals, and the description thereof is omitted.

The engine 120 shown in FIG. 5 is an air-cooled single-cylinder engine, and is arranged with the crank axis C1 along the left-right direction of the vehicle (vehicle width direction), and the cylinder portion 123 is substantially vertical (slightly forward tilted) on the crankcase 21. The cylinder axis C2 is inclined with respect to the vertical direction so that its upper part is located on the front side.
The fuel supply system of the engine 120 employs an electronically controlled fuel injection device, and detection information from the oil temperature sensor 55 is input as engine temperature information to an electronic control unit (not shown) that controls the operation thereof. .

The cylinder portion 123 differs from the cylinder portion 23 only in the cylinder head 127.
That is, in the cylinder head 127, a single camshaft 131 parallel to the crank axis C1 and a valve operating mechanism 130 mainly including intake and exhaust valves 133 and 134 are disposed. The camshaft 131 is linked to and driven by the crankshaft 22 via the chain transmission mechanism 140. In the drawing, the symbol C3 ′ indicates the rotation center axis of the camshaft 131.

  Intake and exhaust ports 135 and 136 are formed in the rear portion and the front portion of the cylinder head 127, and the combustion chamber side openings of these ports 135 and 136 are opened and closed by the intake and exhaust valves 133 and 134, respectively. An intake passage 24a connected to the intake port 135 is formed in the throttle body 24, and the intake passage 24a is opened and closed by a butterfly throttle valve 24b. An injector 24c for injecting fuel into the intake passage 24a is attached to the throttle body 24 under the control of the electronic control unit.

  The engine oil supplied to the valve mechanism 130 is returned to the crankcase 21 through the cam chain chamber 141 that houses the chain transmission mechanism 140 on the left side of the cylinder portion 123. That is, the valve operating chamber 142 in the upper part of the cylinder head 127 is an oil chamber that communicates with the crankcase 21 via the cam chain chamber 141.

  The chain transmission mechanism 140 is hung over a cam drive sprocket 140a provided on the left side of the crankshaft 22, a cam driven sprocket 140b fixed to the left end of the camshaft 131, and the sprockets 140a and 140b. And an endless cam chain 140c.

  Referring also to FIG. 6, a pair of left and right intake side bolt insertion holes for fixing bolts for fixing the cylinder head 127 and the cylinder body 26 to the crankcase 21 are provided before and after the bearing portion 133 a of the camshaft 131 in the cylinder head 127. 143, bolt seat surface 143a, exhaust side bolt insertion hole 144, and bolt seat surface 144a are formed.

  Here, the front and rear portions of the valve operating chamber 142 are recessed (increase in depth) (increase in depth) with respect to the periphery of the bearing portion 133a and the bolt seat surfaces 143a and 144a (increase in depth) and exhaust side. Oil jackets 147 and 148 are provided. The upper end of a single intake side valve guide 45a is provided at a portion between the left and right intake side bolt seat surfaces 143a in the bottom wall portion of each oil jacket 147, 148, and the left and right exhaust side bolt seat surfaces 144a An upper end portion of a single exhaust-side valve guide 46a is provided at an intermediate portion.

  The left end portions of the oil jackets 147 and 148 are opened in the cam chain chamber 141, and the engine oil supplied to the valve operating mechanism 130 drops into the oil jackets 147 and 148, and then the cam chain chambers from the left end portions. 141 is returned to the crankcase 21.

  An oil sump 151 that is recessed downward along the cylinder axis C2 is formed in a portion of the bottom wall portion of the intake side oil jacket 147 that is behind the bolt seat surface 143a on the left side (cam chain chamber 141 side). . The oil sump 151 has a substantially cubic shape, and the oil temperature sensor 55 is attached to the cylinder head 127 so that the detection unit 57 faces the oil sump 151. The oil temperature sensor 55 is disposed so that the sensor axis C5 is orthogonal to the cylinder axis C2 and the left-right direction.

  Referring also to FIG. 7, a mounting boss 152 for the oil temperature sensor 55 is formed on the left side of the cylinder outer opening of the intake port 135 in the rear wall portion (intake side wall portion) of the cylinder head 127. . The mounting boss 152 is located immediately behind the oil reservoir 151, and the detection portion 57 of the oil temperature sensor 55 and the bottom of the main body portion 56 are inserted into the mounting boss 152 from the rear, and the detection portion 57 of the oil temperature sensor 55 is inserted into the oil boss 152. The oil temperature sensor 55 is fixed to the cylinder head 127 by being inserted into the reservoir 151 and screwing the neck of the main body 56 to the inner periphery of the mounting boss 152.

As shown in FIGS. 5 and 6, a pivot portion 153 that supports the tensioner arm 161 of the cam chain tensioner 160 located on the rear side of the cam chain chamber 141 is located immediately in front of the oil sump 151.
Here, the arrow F1 in FIG. 5 indicates the rotation direction of the cam drive sprocket 140a (crankshaft 22) during engine operation, and the arrow F2 indicates the rotation direction of the cam driven sprocket 140b (camshaft 131).

  A portion of the cam chain 140c located on the front side of the cam chain chamber 141 is a drawing side (tight side) by the cam drive sprocket 140a, and a portion located on the rear side of the cam chain chamber 141 is a feeding side (from the cam drive sprocket 140a). The slack side). The cam chain 140c is wound around the outer periphery of each sprocket 140a, 140b along a plane orthogonal to the left-right direction.

  A chain guide 160a is fixedly provided on the front side of the cam chain chamber 141 so as to slidably come into contact with the tension side of the cam chain 140c from the outside of the winding region of the cam chain 140c and guide its traveling direction. On the other hand, on the rear side of the cam chain chamber 141, the cam chain 140c is slid on the slack side of the cam chain 140c from the outside of the winding region to guide the traveling direction and an appropriate tension is applied (slack is removed). A cam chain tensioner 160 having a tensioner arm 161 is provided.

  The tensioner arm 161 extends along the longitudinal direction (traveling direction) of the cam chain 140c, and can be elastically bent so as to protrude toward the inside of the winding region of the cam chain 140c in a side view of the engine. The upper end of the tensioner arm 161 extends obliquely forward and upward of the oil reservoir 151, and the lower end of the tensioner arm 161 extends to the rear of the cam drive sprocket 140a. On the right side of the upper end portion of the tensioner arm 161, the pivot portion 153 that protrudes upward from the bottom wall portion of the intake-side oil jacket 147 along the cylinder axis C2 is disposed adjacently.

  A tensioner adjuster 162 having a rotation center axis C6 along the left-right direction passes through the upper end portion of the tensioner arm 161, and the upper end portion of the tensioner arm 161 is connected to the pivot portion 153 and the cam chain chamber 141 via the tensioner adjuster 162. The left side wall (outer wall) is rotatably supported.

  The tensioner adjuster 162 has a cylindrical portion coaxial with the axis C6 and is inserted into and supported by the support hole in the left wall of the cam chain chamber 141, and a columnar eccentric projecting rightward from the right end of the base portion 162a. The shaft 162b has a shaft that is coaxial with the axis C6 and has a support pin 162c that protrudes rightward from the right end of the eccentric shaft 162b and is inserted into and supported by the support hole of the pivot portion 153.

  The left end portion of the base portion 162a of the tensioner adjuster 162 is exposed to the outside of the cylinder portion 123, and the tensioner adjuster 162 can be rotated about the axis C6 by engaging a tool with the left end portion. The eccentric shaft 162b of the tensioner adjuster 162 rotatably supports the upper end portion of the tensioner arm 161, and the tensioner adjuster 162 is rotated about the axis C6 so that the upper end portion of the tensioner arm 161 is positioned about the axis C6. A quantitative displacement is possible. The tensioner adjuster 162 can be fixed at an arbitrary rotational position by a fixing means (not shown).

  On the other hand, the lower end portion of the tensioner arm 161 is rotatably supported by a support bracket 163a below the tensioner bar 163 via a support shaft extending in the left-right direction. The tensioner bar 163 extends up and down along the cylinder axis C2 immediately behind the tensioner arm 161, and an upper portion thereof is inserted and supported in a support hole formed in the rear wall portion of the cam chain chamber 141 so as to be vertically movable. . The tensioner bar 163 is biased upward by the spring force of the tension coil spring 164 that passes through the tensioner bar 163, and the lower end portion of the tensioner arm 161 is biased upward.

  The tensioner arm 161 is bent so as to be pushed forward (on the cam chain 140c side) by the spring force of the tension coil spring 164, and slidably comes into contact with the cam chain 140c from the outside of the winding region to apply a predetermined tension. . At this time, the forward pressing force of the tensioner arm 161 and the tension of the cam chain 140c can be adjusted by the rotation of the tensioner adjuster 162.

  That is, as described above, the tensioner adjuster 162 is rotated to move the upper end of the tensioner arm 161 up and down, thereby changing the curvature of the tensioner arm 161 and changing the amount of the tensioner arm 161 pushed forward. The tension applied to the cam chain 140c is changed. A fixing bolt 165 is attached to the rear wall of the cam chain chamber 141 to fix the tension of the tensioner bar 163 after adjusting the tension of the cam chain 140c.

  As described above, the air-cooled engine 120 in the above embodiment also includes the oil jacket 147 serving as the engine oil flow path for the valve operating mechanism 130 in the cylinder head 127, and the engine oil is provided on the wall of the oil jacket 147. In the same manner as in the first embodiment, an oil temperature sensor 55 is attached to the cylinder head 127 so as to detect an oil temperature in the oil sump 151. The detection accuracy of the air temperature and thus the engine temperature of the air-cooled engine 120 can be improved, the fuel consumption and exhaust gas performance of the air-cooled engine 120 can be improved, and the detection value of the oil temperature sensor 55 due to engine exhaust heat can be improved. The influence of can be suppressed.

  In the air-cooled engine 120, the oil reservoir 151 is disposed above the cylinder axis C2 in the oil jacket 147 and on the cam chain chamber 141 side, and supports the tensioner arm 161 of the cam chain tensioner 160. A pivot portion 153 projects from the wall portion of the oil jacket 147, and the oil reservoir 151 is disposed between the pivot portion 153 and the wall portion of the cylinder head 127, so that engine oil enters and exits the oil reservoir 151. The oil temperature detection accuracy can be further improved by further suppressing the oil pressure.

  The present invention is not limited to the above-described embodiment. For example, the oil temperature sensor 55 may be arranged with a predetermined angle in a side view of the cylinder without being orthogonal to the cylinder axis C2. Similarly, the hydraulic sensor 55 may be configured to be arranged at a predetermined angle when viewed from the top of the cylinder without being orthogonal to the left-right direction.

Further, the present invention is not limited to a single-cylinder engine, and may be applied to a multi-cylinder engine of various types such as a parallel type and a V-type, and may be applied to a vertically placed engine having a crank axis line along the vehicle longitudinal direction. Furthermore, you may apply to the engine which drives a cam shaft using the transmission mechanism using a gear and a shaft instead of a chain type.
And the structure in the said Example is an example of this invention, It can apply not only to a two-wheeled motor vehicle but to a three-wheeled or four-wheeled vehicle, Of course, a various change is possible in the range which does not deviate from the summary of the said invention. Needless to say.

1 is a left side view of a motorcycle according to an embodiment of the present invention. It is sectional drawing orthogonal to the left-right direction of the cylinder head of the engine of the said motorcycle. It is AA sectional drawing of FIG. FIG. 3 is a view taken in the direction of arrow B in FIG. It is sectional drawing orthogonal to the left-right direction around the cylinder part of the engine in 2nd Example of this invention. It is a top view of the cylinder head of the engine shown in FIG. It is C arrow line view of FIG.

Explanation of symbols

20,120 Air-cooled engine 21 Crankcase 22 Crankshaft 23,123 Cylinder part C2 Cylinder axis 24 Throttle body (intake system parts)
24c Injector (fuel injection valve)
26 Cylinder body 26a Cylinder bore 26b Piston 27, 127 Cylinder head 30, 130 Valve mechanism 35, 135 Intake port 40 Transmission mechanism 41 Transmission mechanism accommodation chamber 47, 147 Intake side oil jacket (oil jacket)
48,148 Exhaust side oil jacket (oil jacket)
15,151 Oil sump 52 Mounting boss (mounting part)
53 Ribs (Wall)
55 Oil temperature sensor 56 Main body (operated part)

Claims (5)

A crankcase that rotatably supports the crankshaft, and a cylinder portion that has a cylinder bore that slidably fits a piston coupled to the crankshaft and that forms a fuel chamber that faces the top of the piston, In the air-cooled engine in which the cylinder portion includes a cylinder body that forms the cylinder bore, and a cylinder head that is coupled to the cylinder body and supports a valve mechanism.
The cylinder head is provided with an oil jacket serving as an engine oil flow path for the valve mechanism, and an oil reservoir for retaining the engine oil is provided in a part of the oil jacket, and the oil temperature in the oil reservoir is reduced. An air-cooled engine, wherein an oil temperature sensor is attached to the cylinder head for detection.   The air-cooled engine according to claim 1, further comprising a fuel injection valve that controls a fuel injection amount based on a detection value of the oil temperature sensor.   The air-cooled engine according to claim 1 or 2, wherein the oil temperature sensor is disposed adjacent to an intake system component connected to an intake port of the cylinder head.   The cylinder head has a wall portion that covers an operated portion of the oil temperature sensor from a side opposite to the intake system component, and the wall portion is disposed adjacent to an attachment portion of the oil temperature sensor. The air-cooled engine according to claim 3.   The cylinder portion is provided to be inclined with respect to the vertical direction, and a transmission mechanism that communicates the inside of the crankcase with the inside of the cylinder head to accommodate a transmission mechanism that transmits the power of the crankshaft to the valve mechanism. 5. The fuel tank according to claim 1, further comprising a storage chamber, wherein the oil reservoir is disposed above a cylinder axis of the oil jacket and opposite to the transmission mechanism storage chamber. Air-cooled engine.

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