JPWO2018180383A1 - Internal combustion engine for straddle-type vehicles - Google Patents

Abstract

Provided is an internal combustion engine for a straddle-type vehicle having a pressure sensor arrangement structure that does not interfere with surrounding engine-related members even when a single cylinder engine is provided with a pressure sensor, thereby improving the efficiency of the manufacturing process. An intake port 95 and an exhaust port 101 are provided on upper and lower surfaces of a cylinder head 35b, and an engine-related member 70 is disposed on one side surface 35b0 of the cylinder head 35b. On the other side surface 35b1, a spark plug 133 and a pressure sensor 144 for detecting the pressure in the combustion chamber 92 are arranged. The ignition plug 133 and the hole 142 in which the pressure sensor 144 is arranged are in the same axial direction. Provided above.

Description

  The present invention relates to an internal combustion engine for a straddle-type vehicle.

  Patent Document 1 discloses an arrangement structure in which a pressure sensor for detecting an in-cylinder pressure is disposed in a water jacket around a combustion chamber of a cylinder head.

JP-A-5-312093

However, since engine-related members such as an oil pump, an intake / exhaust pipe, and a cam chain tensioner are concentrated around the combustion chamber of the engine, the layout of the pressure sensors is limited. Further, when the pressure sensor is disposed on the cylinder head, it is necessary to form a hole in the cylinder head for detecting the pressure in the combustion chamber, which increases the number of processing steps.
The present invention has been made in view of the above-described circumstances, and even when a pressure sensor is provided in an engine, a straddle structure of a pressure sensor arrangement structure that does not interfere with surrounding engine-related members and streamlines the manufacturing process. It is intended to provide an internal combustion engine of a type vehicle.

This specification includes the entire contents of Japanese Patent Application No. 2017-061765 filed on March 27, 2017.
According to the present invention, an intake port (95) and an exhaust port (101) are provided on the upper and lower surfaces of a cylinder head (35b), and an engine-related member (70) is provided on one side surface (35b0) of the cylinder head (35b). In the internal combustion engine of a straddle-type vehicle, a pressure sensor (144) for detecting the pressure of a spark plug (133) and a pressure in a combustion chamber (92) is disposed on the other side surface (35b1) of the cylinder head (35b). The ignition plug (133) and the holes (142, 241) in which the detection part (144b) of the pressure sensor (144) is arranged are provided on the same axial direction.

  In the above invention, the pedestal surface (131) of the ignition plug (133) and the pressure sensor (144) are provided within a vertical range of a stud bolt (81) connecting the cylinder head (35b) and the cylinder block (35a). The pressure sensor (144) and the ignition plug are provided such that the pedestal surface (131) of the spark plug (133) and the pedestal surface (141) of the pressure sensor (144) are continuous. (133) may be disposed, and the cap (151) of the ignition plug (133) and the pressure sensor (144) may be disposed at a predetermined interval.

  Further, in the above invention, the internal combustion engine (30) is swingably attached to the vehicle body (1) via a link mechanism (38) provided on an upper portion of the crankcase (34), and the pressure sensor (144) May be arranged in a direction along the swing direction of the internal combustion engine (30).

  In the above invention, the harness (161) of the oxygen sensor (150) and the harness (163) of the pressure sensor (144) may be bundled and attached to the internal combustion engine (30).

  In the above invention, the hole (142) is a support hole (142) for the pressure sensor (144), and includes a support hole (132) for the ignition plug (133) and a support hole for the pressure sensor (144). (142) may be provided in parallel, and the ignition plug (133) and the pressure sensor (144) may be arranged in parallel.

  In the above invention, the support hole (242) of the pressure sensor (144) is formed continuously with the hole (241), and the support hole (132) of the ignition plug (133) and the pressure sensor (142) are formed. The support hole (142) of (144) may be provided to be inclined, and the pressure sensor (144) may be arranged to be inclined with respect to the ignition plug (133).

  An internal combustion engine of a straddle-type vehicle according to the present invention is provided with intake ports and exhaust ports on upper and lower surfaces of a cylinder head, an engine-related member disposed on one side surface of the cylinder head, and the other side of the cylinder head. A spark plug and a pressure sensor for detecting the pressure in the combustion chamber are arranged on the side surface of the fuel cell, and the spark plug and a hole in which the detection unit of the pressure sensor is arranged are provided in the same axial direction. According to this configuration, the pressure sensor is arranged in a small space around the cylinder head, and the ignition plug and the hole in which the detection unit of the pressure sensor is arranged are arranged in the same axial direction, so that the ignition is performed. The sensor hole in the same direction as the plug hole can be processed at the same time, and the manufacturing process can be simplified.

  In the above invention, a pedestal surface of the spark plug and a pedestal surface of the pressure sensor are provided within a vertical range of a stud bolt connecting the cylinder head and the cylinder block, and a pedestal surface of the ignition plug and a pedestal surface of the pressure sensor are provided. The pressure sensor and the spark plug may be arranged such that the pedestal surface is continuous, and the cap of the spark plug and the pressure sensor may be arranged at a predetermined interval. According to this configuration, the ignition plug and the pressure sensor can be arranged in a small space on the side of the cylinder head. In addition, the pressure sensor can be arranged at a position where the noise of the ignition plug is not easily received.

Further, in the above invention, the internal combustion engine is swingably attached to a vehicle body via a link mechanism provided at an upper part of a crankcase, and the pressure sensor is disposed in a direction along a swing direction of the internal combustion engine. May be. According to this configuration, the pressure sensor can be arranged so as not to be easily affected by the swing of the engine.
In the above invention, the harness of the oxygen sensor and the harness of the pressure sensor may be bundled and attached to the internal combustion engine. According to this configuration, the harness can be simplified.

  Further, in the above invention, the hole is a support hole of the pressure sensor, a support hole of the ignition plug and a support hole of the pressure sensor are provided in parallel, and the ignition plug and the pressure sensor are parallel. They may be arranged side by side. According to this configuration, the hole in which the detection unit of the pressure sensor is arranged can be used as a support hole for the pressure sensor, and a space for disposing the pressure sensor can be reduced as compared with a case where holes are separately provided. The manufacturing process can be simplified. Further, the pressure sensor and the spark plug can be adjacent to each other in parallel.

  Further, in the above invention, a support hole of the pressure sensor is formed continuously with the hole, a support hole of the ignition plug and a support hole of the pressure sensor are provided at an angle, and the pressure sensor includes: The spark plug may be arranged obliquely with respect to the spark plug. According to this configuration, when the support hole of the spark plug and the hole in which the detection unit of the pressure sensor is disposed are provided side by side in the same axial direction, the pressure sensor is disposed obliquely with respect to the spark plug. Thereby, the pressure sensor and the ignition plug can be arranged adjacent to each other, and the degree of freedom of arrangement of the pressure sensor can be improved.

FIG. 1 is a left side view of the saddle-ride type vehicle according to the first embodiment of the present invention. FIG. 2 is a right side view of the unit swing engine of the straddle-type vehicle. FIG. 3 is a left side view of the cylinder head of the unit swing engine. FIG. 4 is a perspective view of the cylinder head viewed from the axial direction of the spark plug. FIG. 5 is a sectional view taken along line VV of FIG. FIG. 6 is a sectional view of the engine according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, directions such as front and rear, left and right, and up and down are the same as directions with respect to the vehicle body unless otherwise specified. In addition, reference numeral FR shown in each drawing indicates the front of the vehicle body, reference numeral UP indicates the upper part of the vehicle body, and reference numeral LH indicates the left side of the vehicle body.

<First embodiment>
FIG. 1 is a left side view of the saddle-ride type vehicle according to the first embodiment of the present invention. In FIG. 1, only the left side is provided as a pair provided on the left and right sides.
The straddle-type vehicle 1 is a scooter-type motorcycle having a low-floor step floor 11 on which an occupant sitting on a seat 10 places his / her feet.
A front wheel 2 is provided in front of the vehicle body frame 12, and a rear wheel 3, which is a driving wheel, is supported by a unit swing engine 13 arranged at the rear of the vehicle.

  The straddle-type vehicle 1 includes a front fork 14 pivotally supported by a front end of a body frame 12, and the front wheel 2 is pivotally supported by a lower end of the front fork 14. A handle 15 steered by an occupant is attached to an upper end of the front fork 14. The saddle-ride type vehicle 1 includes a vehicle body cover 16 that covers the vehicle body such as the vehicle body frame 12.

  The body frame 12 includes a head pipe 17 provided at a front end, a main frame 18 extending rearward and downward from the head pipe 17, a rear side connected to a lower side surface of the main frame 18, and extending rearward and upward from a lower end. The vehicle includes a pair of left and right side frames 19, 19, and a pair of left and right seat frames 20, 20 connected to upper ends of the side frames 19, 19 and extending upward and rearward.

  The side frames 19, 19 and the seat frames 20, 20 are formed in a pipe shape extending in the front-rear direction. The side frames 19, 19 include horizontal portions 21, 21 extending rearward from the main frame 18, and inclined portions 22, 22 extending rearward upward from rear ends of the horizontal portions 21, 21. Each of the side frames 19, 19 and the seat frames 20, 20 is connected in the vehicle width direction by a cross frame (not shown).

FIG. 2 shows a support structure of the unit swing engine 13.
The unit swing engine 13 is configured such that a single-cylinder engine 30 that is an internal combustion engine and an arm 31 that supports the rear wheel 3 are integrated. The engine 30 includes a crankcase 34 that accommodates a crankshaft 33 (see FIG. 1) extending in the vehicle width direction, and a cylinder 35 that extends forward from a front portion of the crankcase 34.
The cylinder 35 includes a cylinder block 35a, a cylinder head 35b, and a head cover 35c in order from the crankcase 34 side. The axis 35d of the cylinder bore of the cylinder 35 extends substantially horizontally in a slightly upward posture.

  The arm 31 that supports the rear wheel 3 has a hollow case shape, and a belt-type continuously variable transmission (not shown) that transmits the output of the engine 30 to the rear wheel 3 is housed inside the arm 31. . The rear wheel 3 is supported on the right side of the arm 31. The lower end of a rear suspension 42 is supported by the arm 31, and the upper end of the rear suspension 42 is connected to the seat frame 20 (not shown in FIG. 2). The rear suspension 42 attenuates the swing of the unit swing engine 13.

A pair of left and right engine brackets 28 are provided so as to protrude rearward from the inclined portions 22, 22 from the rear surfaces of the inclined portions 22, 22 of the side frames 19, 19. The engine brackets 28, 28 are provided with a pivot shaft 39 that connects the engine brackets 28, 28 in the vehicle width direction.
The pivot shaft 39 supports the front ends of the connecting pieces 38b, 38b of the link mechanism 38, and the rear ends of the connecting pieces 38b, 38b support a rod-shaped link stay 38a extending in the vehicle width direction. Have been. The link stay portion 38a is fixed to an upper portion of the crankcase 34 of the unit swing engine 13. The link stay 38a and the connecting pieces 38b, 38b constitute a link mechanism 38.

  According to the above configuration, the unit swing engine 13 has the upper part swingably connected to the inclined parts 22, 22 by the pivot shaft 39 (upper link connection), and the rear part of the unit swing engine 13 through the rear suspension 42. , 20 are connected. The unit swing engine 13 is disposed behind the inclined portions 22, 22 and is supported via a link mechanism 38 so as to be suspended from the inclined portions 22, 22 of the side frame 19. The unit swing engine 13 is easy to swing back and forth.

  As shown in FIG. 1, the vehicle body cover 16 has a front cover 43 that covers an upper front part of the vehicle body. A pair of left and right front side covers 44, 44 each having an L-shape in a side view are connected to the side of the front cover 43, and the front side of the vehicle body is covered with the front side covers 44, 44. The rear of the front side covers 44, 44 is covered by an upper inner cover 45 and a lower inner cover 46, and the front forks 14, the head pipe 17, and the like are covered by the front side covers 44, 44, the upper inner cover 45, and the lower inner cover 46. Have been done. Below the front side covers 44, a pair of left and right lower covers 47, 47 constituting the step floor 11, 11 are connected, and the lower cover 47 extends above the unit swing engine 13.

  The lower part of the lower covers 47, 47 is covered by a pair of left and right under cowls 48, 48. The space between the lower covers 47, 47 and the seat 10 is covered by a pair of left and right rear side covers 49, 49 extending rearward with the front end connected to the rear end of the front side covers 44, 44. At the rear of the rear side covers 49, a grab rail 50, a combination lamp 51, and a rear fender 52 that are held by a passenger are attached in order from the top. The saddle-ride type vehicle 1 includes a front fender 9 that covers the front wheel 2 from above.

  As shown in FIG. 2, the exhaust pipe 36 of the engine 30 has a front end connected to the cylinder head 35b and extends rearward, and a rear end connected to the muffler 37. The muffler 37 is disposed on the right side (one side) of the rear wheel 3. The exhaust pipe 36 includes a catalyst device 60 for purifying exhaust gas in the middle of the exhaust passage. The exhaust pipe 36 including the catalyst device 60 is disposed using a space below the cylinder 35 and the crankcase 34. Since the exhaust pipe 36 including the catalyst device 60 and the muffler 37 are fixed to the unit swing engine 13, the exhaust pipe 36 swings around the pivot shaft 39 integrally with the unit swing engine 13. An exhaust port 101 is formed below the cylinder head 35b, and an upstream end of the exhaust pipe 36 is connected to a downstream end 102 of the exhaust port 101.

  The arm portion 31 extends rearward from the left rear portion of the crankcase 34 and is located on the left side (on the other side) of the rear wheel 3. The rear wheel 3 is pivotally supported by a rear wheel axle 31 a at the rear end of the arm 31, and is supported by the arm 31 in a cantilever manner.

The intake device of the engine 30 includes an air cleaner box 40 (see FIG. 1) and a throttle body (not shown) connected downstream of the air cleaner box 40.
The air cleaner box 40 is supported by the arm 31 and is located above the arm 31. The throttle body (not shown) is disposed in front of the air cleaner box 40 and above the unit swing engine 13, and a downstream end thereof is connected to an intake port 95 at an upper portion of the cylinder head 35b.

The unit swing engine 13 includes a cooling device 70. The cooling device 70 (engine-related member) is arranged on one side in the vehicle width direction. The cooling device 70 includes a water pump 71 provided on the right side surface (one side surface) 35b0 of the cylinder head 35b, a radiator 72 provided on one side of the crankcase 34, a lower portion of the water pump 71 and the engine 30. A first hose 73 connecting the lower part, a second hose 74 connecting the upper part of the engine 30 and the upper part of the radiator 72, a third hose 75 connecting the lower part of the radiator 72 and the water pump 71, A bypass hose 76 for connecting between the hose 74 and the radiator 72;
In the water pump 71, the cooling water is pumped by rotating an impeller (not shown) supported by the cam shaft 63. The cooling water circulates between the radiator 72 and the engine 30 via the hoses 73 to 76.

FIG. 3 is a left side view showing the cylinder head 35b.
As described above, the cooling device 70 including the water pump 71 is arranged on the right side surface (not shown in FIG. 3) of the cylinder head 35b, whereas the small space S is formed on the left side surface of the cylinder head 35b. Is provided. In the present embodiment, the ignition plug 133 and the pressure sensor 144 are attached to the left side surface of the cylinder head 35b exposed in the space S. As shown in FIG. 4, the spark plug 133 and the pressure sensor 144 are arranged so that their respective axial directions are parallel to each other, and are arranged on the same axial direction.

FIG. 5 is a sectional view taken along line VV of FIG.
The cylinder block 35a and the cylinder head 35b are fixed to the crankcase 34 via stud bolts 81 extending in the front-rear direction. The head cover 35c is fixed to the cylinder head 35b with bolts 82. A valve operating chamber (not shown) is provided between the head cover 35c and the cylinder head 35b, and a camshaft 63, an intake valve (not shown), an exhaust valve (not shown), and the like are arranged.
A cylinder bore 90 is formed in the cylinder block 35a, and a combustion chamber 92 is formed in front of the cylinder bore 90.

  An intake valve hole 93 and an exhaust valve hole 94 are formed in the cylinder head 35b, and the intake valve hole 93 is formed at a downstream end of an intake port 95 extending from an upper portion of the cylinder head 35b. An intake pipe 97 is connected to an upstream end 96 of the intake port 95, and a mixture of air supplied from the air cleaner box 40 and fuel injected by a fuel injection device (not shown) is supplied to the combustion chamber 92. You.

  The exhaust valve hole 94 is formed at an upstream end of an exhaust port 101 formed below the cylinder head 35b. The downstream end 102 of the exhaust port 101 is connected to the upstream end of the exhaust pipe 36. On the right side (one side) of the cylinder head 35b and the cylinder block 35a, a housing 108 for a transmission member is formed. A cam chain 84 that transmits the power from the crankshaft 33 to the camshaft 63 is disposed in the housing 108 of the transmission member. The camshaft 63 rotated by the cam chain 84 connects an intake valve (not shown) and an exhaust valve (not shown) via a pair of rocker arms (not shown) between the head cover 35c and the cylinder head 35b. Drive. Thus, the intake valve hole 93 and the exhaust valve hole 94 are opened and closed at a predetermined timing.

  A water jacket 110 through which cooling water flows is formed in the cylinder block 35a and the cylinder head 35b. The water jacket 110 is formed around the cylinder bore 90. The water jacket 110 has a first hose 73 connected to a lower portion of the cylinder head 35b, and a second hose 74 connected to an upper portion of the cylinder head 35b. In the water jacket 110, the cooling water pumped by the water pump 71 passes and cools the engine 30.

In the present embodiment, the ignition plug 133 and the pressure sensor 144 are arranged in the space S between the upper and lower stud bolts 81.
A plug seat surface 131 is provided in the space S, and the plug seat surface 131 is formed in a circular recess on the side surface 35b1 of the cylinder head 35b. At the center of the plug pedestal surface 131, a shaft-shaped plug support hole 132 penetrating from the plug pedestal surface 131 to the combustion chamber 92 is formed. The plug support hole 132 is slightly inclined with respect to the front-rear direction, and extends along the front-rear direction. A shaft-shaped spark plug 133 is fixedly supported in the plug support hole 132. The gasket 133b of the ignition plug 133 comes into contact with the plug pedestal surface 131 to seal the plug support hole 132.

Above the plug pedestal surface 131, a sensor pedestal surface 141 is formed. The sensor pedestal surface 141 is formed as a circular recess on the side surface 35b1 of the cylinder head 35b. The sensor pedestal surface 141 partially overlaps with the plug pedestal surface 131 and forms a recessed shape that is continuous with the plug pedestal surface 131. At the center of the sensor pedestal surface 141, a sensor support hole 142 penetrating in the same direction as the plug support hole 132 is formed. The sensor support hole 142 is formed substantially parallel to the plug support hole 132. Therefore, the sensor support hole 142 and the plug support hole 132 can be processed simultaneously, and the manufacturing process can be simplified.
The sensor support hole 142 has an outer large-diameter hole 142a and a small-diameter hole 142b inside the large-diameter hole 142a. The pressure sensor 144 is inserted and arranged in the sensor support hole 142. The pressure sensor 144 is constituted by a piezoelectric sensor.

The pressure sensor 144 is formed in a shaft shape, and has a cylindrical main body 144a, a detection section 144b having a smaller diameter than the main body 144a, and provided at a distal end of the main body 144a, and formed at a base end of the main body 144a. Terminal portion 144c.
The pressure sensor 144 has the detection unit 144b disposed inside the small-diameter hole 142b, and is disposed so as not to reach the combustion chamber 92. The main body 144a is fixed to the inner wall surface of the large-diameter hole 142a with a gap. The pressure sensor 144 is fixed to the sensor support hole 142 by a screw portion 144d provided on the outer periphery of the pressure sensor 144. The pressure detected by the detection unit 144b is converted into an electric signal by the circuit unit of the main body unit 144a, and is output to the engine 30 or the control unit of the vehicle via the terminal unit 144c.
The sensor support hole 142 is formed adjacent to the water jacket 110, and the thickness of the wall 146 between the sensor support hole 142 and the plug support hole 132 is smaller than the thickness of the wall 146 between the water jacket 110 and the sensor support hole 142. 147 is thinner. The pressure sensor 144 is easily cooled by the cooling water.

As shown in FIGS. 3 and 4, a plug cap 151 is connected to the terminal portion 133 c of the ignition plug 133. The plug cap 151 is spaced apart from the adjacent pressure sensor 144. The plug cap 151 is held at a predetermined interval so as not to be easily affected by the noise of the ignition plug 133 with respect to the pressure sensor 144. The predetermined interval can be set by experiments.
The plug cap 151 is formed in an L shape, and has a cap body 151a connected to the ignition plug 133 and an extension 151b. A high tension cable 154 is connected to the extension 151b. The high tension cable 154 extends to the side opposite to the pressure sensor 144, is fixed to a clamp member 156 extending forward and downward from the stay 155, and is connected to the ignition coil 157 so as to bypass the lower part of the cylinder head 35b. .
The ignition coil 157 is fixed to the stay 155. The high tension cable 154 extends to the side opposite to the pressure sensor 144 and is wired around the pressure sensor 144. Therefore, the pressure sensor 144 is unlikely to be affected by noise due to the high tension cable 154.

An oxygen sensor 150 is arranged at the downstream end 102 of the exhaust port 101 (see FIG. 5). The oxygen sensor 150 detects the oxygen concentration at the exhaust port 101.
An oxygen sensor harness 161 is connected to the oxygen sensor 150. The harness 161 of the oxygen sensor is fixed to the clamp 162 of the stay 155, is arranged in an S shape as shown in FIG. 3, and is connected to the connector 171 of the harness 170. The connector part 171 is fixed to the fixing part 164 of the stay 155, and the harness 161 of the oxygen sensor extends rearward from the connector part 171 as a harness 170 further bundled along the cylinder block 35a. The harness 170 is connected to a control unit (not shown) of the vehicle. The upper portion 161a of the oxygen sensor harness 161 on the connector 171 side is fixed along the front-rear direction.
In the present embodiment, the oxygen sensor 150 is attached to the exhaust port 101 of the cylinder head 35b. However, the oxygen sensor 150 may be provided in the exhaust pipe 36 downstream of the exhaust port 101.

The pressure sensor 144 extends along the front-back direction. A sensor harness 163 is connected to the terminal 144c of the pressure sensor 144. After extending in the front-rear direction, the sensor harness 163 is bent in a U-shape and bound by an upper portion 161a of the harness 161 of the oxygen sensor by a binding member 165. On the rear side of the binding member 165, the sensor harness 163 is bundled with the harness 170 and connected to a control unit (not shown) of the vehicle.
One end of the sensor harness 163 is fixed to the pressure sensor 144 along the front-rear direction, and the other end is fixed together with the harness 161 of the oxygen sensor along the front-rear direction. Therefore, the sensor harness 163 is arranged along the front-rear direction. You.
In the present embodiment, since the sensor harness 163 connected to the pressure sensor 144 extends in the front-back direction, when the unit swing engine 13 swings in the front-back direction, the sensor harness 163 swings in the same direction. In addition, poor contact and poor mounting between the pressure sensor 144 and the sensor harness 163 are suppressed. Therefore, the swing of the unit swing engine 13 hardly affects the sensor harness 163, and the pressure sensor 144 can be arranged so as not to be easily affected by the swing of the unit swing engine 13.
Since the harness 161 of the oxygen sensor and the sensor harness 163 are bound, the harness can be simplified as compared with a case where the harnesses 161 and 163 are not bound.

In the present embodiment, the pressure sensor 144 detects the pressure in the sensor support hole 142 connected to the combustion chamber 92, and is arranged so as not to reach the combustion chamber 92. The pressure in the combustion chamber 92 can be accurately detected. By adjusting the ratio of fuel and air in the air-fuel mixture based on the detection result of the pressure sensor 144, abnormal combustion of the air-fuel mixture in the combustion chamber 92, that is, knocking can be prevented.
In the present embodiment, in the engine 30, the ignition plug 133 and the pressure sensor 144 for detecting the pressure in the combustion chamber 92 are provided on the other side surface 35b1 of the cylinder head 35b in the vehicle width direction in the same axial direction. Is placed on top.
By arranging the pressure sensor 144 in the small space S around the cylinder head 35b and arranging the ignition plug 133 and the pressure sensor 144 in the same axial direction, the plug support hole 132 of the ignition plug 133 and the sensor support hole 142 can be processed at the same time, and the processing steps can be simplified.
Even when the pressure sensor 144 is provided in the single-cylinder engine 30, the processing process can be made more efficient without interfering with the surrounding engine-related members 70.

In the present embodiment, a plug pedestal surface 131 and a sensor pedestal surface 141 are provided adjacent to each other between the stud bolts 81 and 81 in the up-down direction so as to be continuous, and a spark plug is provided on each of the pedestal surfaces 131 and 141. 133 and a pressure sensor 144 are provided adjacent to each other.
Therefore, in the present embodiment, the ignition plug 133 and the pressure sensor 144 can be arranged in the small space S avoiding the stud bolt 81 with respect to the side surface 35b1 of the cylinder head 35b.
In the present embodiment, the plug cap 151 of the ignition plug 133 and the pressure sensor 144 are arranged at a predetermined interval, and are located at a position where the noise of the ignition plug 133 is less susceptible to noise than when the interval is smaller than the predetermined interval. A pressure sensor 144 can be provided. In particular, since the plug cap 151 is L-shaped and the high tension cable 154 extends on the opposite side to the pressure sensor 144, the pressure sensor 144 can be arranged at a position where the noise of the ignition plug 133 is not easily received.

In the present embodiment, the sensor harness 163 connected to the pressure sensor 144 extends in a direction along the swing direction of the engine 30. One end of the sensor harness 163 is fixed to the pressure sensor 144, and the other end is fixed to the fixing portion 164 together with the harness 161 of the oxygen sensor. When the unit swing engine 13 swings in the front-rear direction, the sensor harness 163 is less likely to swing relatively to the pressure sensor 144, so that the occurrence of a poor contact between the pressure sensor 144 and the sensor harness 163 and a mounting failure are suppressed. You. Therefore, the pressure sensor 144 can be arranged so as not to be easily affected by the swing of the unit swing engine 13.
In the present embodiment, the harness 161 and the sensor harness 163 of the oxygen sensor are bundled, so that the harness 170 is simplified.

  In the present embodiment, the hole 142 where the detection unit 144b of the pressure sensor 144 is disposed is the sensor support hole 142 where the pressure sensor 144 is supported, and the plug support hole 132 and the sensor support hole 142 are provided in parallel. , The ignition plug 133 and the pressure sensor 144 are arranged side by side in parallel. Therefore, as compared with the case where the detection unit 144b of the pressure sensor 144 is disposed, the hole for detecting the pressure by the pressure sensor 144 is shared with the sensor support hole 142 on which the pressure sensor 144 is supported, and the holes are separately provided. The space for disposing the pressure sensor 144 can be reduced, and the manufacturing process can be simplified. Further, the pressure sensor 144 and the spark plug 133 can be adjacent to each other in parallel.

<Second embodiment>
FIG. 6 is an explanatory diagram of the second embodiment.
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
In the second embodiment, the configuration in which the pressure sensor 144 is arranged is different from the first embodiment. A through hole 241 is formed at an upper portion of the plug support hole 132 substantially in parallel with the plug support hole 132. The through hole 241 extends from the side surface 35b1 of the cylinder head 35b to the combustion chamber 92. In the through hole 241, a sensor support hole 242 branches obliquely outward from the side and is formed continuously. The sensor support hole 242 is the same as the sensor support hole 142 of the first embodiment except that the formation position is different, and has a large-diameter hole 142a and a small-diameter hole 142b. The pressure sensor 144 is inserted and fixedly supported in the sensor support hole 242. The pressure sensor 144 is arranged such that the detection part 144b is arranged in the through hole 241 and does not reach the combustion chamber 92. The through hole 241 is sealed by a gasket 133d provided on the ignition plug 133.

  In the second embodiment, the through hole 241 is connected to the combustion chamber 92, and the pressure inside the through hole 241 is detected by the pressure sensor 144, so that the pressure in the combustion chamber 92 can be detected. Can be prevented. Also in the second embodiment, the through hole 241 which is a space in which the detection unit 144b is disposed and in which pressure is detected is formed in the same direction as the plug support hole 132, thereby facilitating the processing.

  In the second embodiment, the sensor support hole 242 is formed continuously with the hole 241 where the detection unit 144b of the pressure sensor 144 is disposed, and the plug support hole 132 and the sensor support hole 242 are provided at an angle, The sensor 144 is arranged to be inclined with respect to the ignition plug 133. Therefore, when the plug support hole 132 and the hole 241 in which the detection unit 144b of the pressure sensor 144 are arranged are provided side by side in the same axial direction, the pressure sensor 144 is arranged to be inclined with respect to the ignition plug 133. Thus, the pressure sensor 144 and the ignition plug 133 can be arranged adjacent to each other, and the degree of freedom of arrangement of the pressure sensor 144 arranged in the small space S can be improved.

The above-described embodiments merely show one aspect of the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention.
Although the pressure sensor 144 has been described as being fixed with screws by the screw portion 144d, the pressure sensor 144 may be fixed with another member such as a plug.
Although the configuration of the piezoelectric sensor has been described as the pressure sensor 144, any pressure sensor can be used as long as the pressure can be detected.
In the embodiment described above, the configuration of the unit swing engine 13 having the upper link has been described. However, the present invention can be applied to the configuration of the lower link.
The present invention is particularly effective in an engine configuration in which a cooling device is arranged on the side of a cylinder head, such as a single-cylinder engine of a water-cooled engine, but is not limited to the number of cylinders of the engine or the vehicle configuration. The present invention is applicable to various types of engines and vehicles.

DESCRIPTION OF SYMBOLS 1 Body 35b Cylinder head 35b0 One side surface 35b1 The other side surface 30 Internal combustion engine 34 Crankcase 38 Link mechanism 70 Engine related member 81 Stud bolt 92 Combustion chamber 94, 101 Intake / exhaust port 131 Base surface 133 Spark plug 141 Base surface 144 Pressure sensor 150 Oxygen sensor 151 Cap 161 Harness 163 Harness

Claims (6)

A saddle in which an intake port (95) and an exhaust port (101) are provided on the upper and lower surfaces of a cylinder head (35b), and an engine-related member (70) is arranged on one side surface (35b0) of the cylinder head (35b). In an internal combustion engine of a riding type vehicle,
A pressure sensor (144) for detecting the pressure of the ignition plug (133) and the pressure in the combustion chamber (92) is disposed on the other side surface (35b1) of the cylinder head (35b). An internal combustion engine for a straddle-type vehicle, wherein the holes (142, 241) in which the detecting portions (144b) of the sensors (144) are arranged are provided in the same axial direction. The pedestal surface (131) of the ignition plug (133) and the pedestal surface (131) of the pressure sensor (144) are located within the vertical range of the stud bolt (81) connecting the cylinder head (35b) and the cylinder block (35a). 141) is provided,
The pressure sensor (144) and the spark plug (133) are arranged so that the seat surface (131) of the spark plug (133) and the seat surface (141) of the pressure sensor (144) are continuous. The internal combustion engine of a straddle-type vehicle according to claim 1, wherein the cap (151) of (133) and the pressure sensor (144) are arranged at a predetermined interval. The internal combustion engine (30) is swingably attached to the vehicle body (1) via a link mechanism (38) provided on the upper part of the crankcase (34),
The internal combustion engine of a straddle-type vehicle according to claim 1, wherein the pressure sensor (144) is arranged in a direction along a swing direction of the internal combustion engine (30).   The harness (161) of the oxygen sensor (150) and the harness (163) of the pressure sensor (144) are bundled and attached to the internal combustion engine (30). An internal combustion engine for a straddle-type vehicle according to claim 1. The hole (142) is a support hole (142) for the pressure sensor (144),
The support hole (132) of the ignition plug (133) and the support hole (142) of the pressure sensor (144) are provided in parallel,
The internal combustion engine of a straddle-type vehicle according to any one of claims 1 to 4, wherein the ignition plug (133) and the pressure sensor (144) are arranged side by side in parallel. A support hole (242) of the pressure sensor (144) is formed continuously with the hole (241),
A support hole (132) of the ignition plug (133) and a support hole (142) of the pressure sensor (144) are provided to be inclined.
The internal combustion engine of a straddle-type vehicle according to any one of claims 1 to 4, wherein the pressure sensor (144) is arranged to be inclined with respect to the ignition plug (133).

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