JP2006183489A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine wherein a cooling water delivery hole formed on a cylinder head in order to delivery cooling water and a sensor attachment hole formed on the cylinder head in order to attach a water temperature sensor and an exhaust gas sensor are arranged so that the axes are almost in parallel. <P>SOLUTION: The engine 50 is provided with a cylinder head 52 equipped with an exhaust port 61 for delivering the exhaust gas to the outside, a water jacket 122 to which the cooling water is supplied, a cooling water lead-out passage 121a for delivering the cooling water from the water jacket 122, O<SB>2</SB>sensor attachment hole 116a communicating with the exhaust port 61 so that O<SB>2</SB>sensor 116 detecting oxygen concentration of the exhaust gas in the exhaust port 61 is attached thereto, and a water temperature sensor attachment hole 119a communicating with the water jacket 122 so that the water temperature sensor 119 detecting the water temperature of the cooling water is attached thereto. The axes of the cooling water lead-out passage 121a, the O<SB>2</SB>sensor attachment hole 116a and the water temperature sensor attachment hole 119a are almost in parallel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine that is mounted on a scooter type vehicle or the like and runs the vehicle, and in particular, the efficiency of processing by arranging the axes of sensor mounting holes and the like formed in a cylinder head so as to be substantially parallel. It is related with the engine which improved.

  In order to reduce the harmful substances contained in the exhaust gas, it is necessary to keep the ratio of air and fuel optimal according to the state of the engine, so a water temperature sensor that measures the temperature of the cooling water that cools the cylinder head, An exhaust gas sensor for measuring the amount of oxygen contained in the exhaust gas is attached to the cylinder head, and is controlled by these detected values (see, for example, Patent Document 1).

JP-A-11-200903

  However, since the axial directions of the sensor mounting holes for mounting these sensors on the cylinder head and the cooling water discharge holes for discharging cooling water to the outside do not match, the angle of the processing axis when drilling the holes There is a problem in that conversion is necessary, processing time is extended, and cost is increased.

  This invention is made | formed in view of such a subject, and is formed in a cylinder head in order to attach a cooling water discharge hole formed in a cylinder head for discharging cooling water, a water temperature sensor, and an exhaust gas sensor. An object of the present invention is to provide an engine that is arranged so that the axes of sensor mounting holes are substantially parallel.

  In order to solve the above-described problems, an engine according to the present invention includes an exhaust port for discharging exhaust gas to the outside, a water jacket to which cooling water is supplied, and a cooling water discharge hole for discharging cooling water from the water jacket (for example, The exhaust gas sensor mounting hole (for example, the O 2 sensor 116 in the embodiment) that is connected to the cooling water outlet passage 121a) in the embodiment and communicates with the exhaust port and detects the oxygen concentration of the exhaust gas in the exhaust port (for example, the O 2 sensor 116 in the embodiment). For example, it has a cylinder head in which an O2 sensor mounting hole 116a) in the embodiment and a water temperature sensor mounting hole that communicates with the water jacket and in which a water temperature sensor that detects the temperature of cooling water in the water jacket is mounted are formed. The axes of the cooling water discharge hole, exhaust gas sensor mounting hole, and water temperature sensor mounting hole are substantially flat. It is arranged to be.

  When the engine according to the present invention is attached to the vehicle body (for example, the vehicle body frame 2 in the embodiment), the cooling water discharge hole and the exhaust gas sensor are attached so that the axis extends laterally and upward of the vehicle body. It is preferable that a hole and a water temperature sensor mounting hole are disposed.

  Further, the engine according to the present invention has a radiator for radiating the cooling water discharged from the water jacket, and the cooling water discharge hole is arranged so that the axis of the cooling water discharge hole extends toward the radiator. Preferably it is.

  Furthermore, it is preferable that the seat surface on which the cooling water discharge hole is formed and the seat surface on which the water temperature sensor mounting hole is formed are located on the same plane.

  When the engine according to the present invention is configured as described above, when the cooling water discharge hole, the exhaust gas sensor mounting hole, and the water temperature sensor mounting hole are processed into the cylinder head, it is not necessary to convert the angle of the processing axis, and processing is easy. Therefore, processing time can be shortened. In addition, it is easy to attach the cooling water pipe to the cooling water discharge hole and to attach the exhaust gas sensor and the water temperature sensor to the sensor mounting hole, and the assembly work time can be shortened.

  At this time, when the engine according to the present invention is attached to the vehicle body, the axial line extends from the side of the vehicle body and upwards, so that when the engine is assembled, Can be easily performed.

  Further, by arranging the cooling water discharge hole so as to extend toward the radiator, the length of the cooling water pipe connecting the cooling water discharge hole and the radiator can be shortened.

  Furthermore, since the seating surfaces on which the cooling water discharge holes and the water temperature sensor mounting holes are formed are positioned on substantially the same plane, the respective seating surfaces can be processed simultaneously, so that the processing cost can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, a scooter type vehicle 1 on which an engine according to the present invention is mounted will be described with reference to FIG. The scooter-type vehicle 1 has a body frame 2, which is positioned at the front portion thereof, and has a head pipe 3 extending in the vertical direction, a down frame 4 extending downward from the head pipe 3, and a down frame. The frame 4 includes a pair of left and right side frames 5 extending downward and rearward and further rearward and obliquely upward from a substantially central portion of the frame 4, and an arcuate curved frame 7 attached to the side frames 5 via side plates 6. .

  A steering shaft (not shown) is rotatably attached to the head pipe 3, and a front fork 8 is attached to the lower end of the steering shaft. A front wheel 9 is supported at the lower end of the front fork 8. On the other hand, a handle post 10 is attached to the upper end of the steering shaft. Further, a handle 11 is attached to the upper end of the handle post 10, and the front wheel 9 can be steered by operating the handle 11. An upper stay 12 and a lower stay 13 are attached to extend forward from the head pipe 3, and a front car 14 is attached to the front ends of these upper and lower stays 12, 13.

  A fuel tank 15 is attached between the pair of side frames 5 below the pair of side frames 5. A link attachment portion 48 formed at the front end of the power unit 16 is attached to the rear end of the curved frame 7 located behind the fuel tank 15 so as to be swingable up and down, and at the rear end of one of the side frames 5 The rear end of the power unit 16 is attached via the cushion unit 17. Here, the fuel tank 15 is provided with a fuel pump 18 having an overturn sensor inside, and is configured to be able to supply fuel from a fuel filler port (cap) 19 provided at the top. The power unit 16 includes an engine 50, a transmission 90, a throttle body 21, an air cleaner 22, an exhaust pipe 23 extending rearward from the engine 50, and a muffler 24 connected to the rear end of the exhaust pipe 23. Is done. A rear wheel 25 is attached to the rear end of the power unit 16, and the rear wheel 25 is driven by the power unit 16 so that the scooter type vehicle 1 can travel with power.

  A luggage box 26 and a grab rail 20 are attached to the rear portion of the side frame 5. The luggage box 26 is supported at the front by a front cross pipe 27 attached to the side frame 5 via the front plate 28, and supported at the rear by a portal frame 29 attached to the side frame 5. The grab rail 20 is supported by a rear stay 30 extending upward from the side frame 5. The helmets 31 and 32 represent a state of being stored in the luggage box 26. A rear storage box 33 is attached to the rear part of the grab rail 20.

  In the scooter type vehicle 1 configured as described above, the front upper portion of the vehicle body is covered with the front cover 34, and the left and right front side covers 35 are attached to the lower side of the front cover 34. A turn signal lamp (not shown) is attached to the front side cover 35. A front inner cover 36 is attached to the rear portion of the front cover 34, and a side portion of the step floor 37 on which the driver and the passenger rest his / her feet is covered with a side cover and an under cover 38. Further, a seat 39 is attached to the upper portion of the luggage box 26, and the lower periphery of the seat 39 is covered with the body cover and the body side cover 40. Further, a handle cover 42 that covers the handle 11 is attached to the upper portion of the front cover 34, and a head lamp 43 is attached to the handle cover 42. A front fender 44 is attached so as to cover the upper part of the front wheel 9, and a rear fender 45 is attached so as to cover the upper part of the rear wheel 25.

  A tail lamp 46 is disposed below the grab rail 20, and a battery 41 is stored between the front cover 34 and the front inner cover 36.

  Next, details of the power unit 16 will be described with reference to FIGS. In the present embodiment, the direction of the arrow F in FIG. 2 is the front, and the direction of the arrow U in FIG. The engine 50 configuring the power unit 16 includes a cylinder head cover 51, a cylinder head 52, a cylinder block 53, and a crankcase 54. In a cylinder chamber 55a formed by being surrounded by a cylinder sleeve 55 fitted in the cylinder block 53, a piston 56 is disposed so as to be slidable in the vertical direction. The piston 56 is connected to a crankcase via a connecting rod 57. It is connected to a crankshaft 58 that is rotatably held in 54. An intake port 60 and an exhaust port 61 communicate with the combustion chamber 59 formed by the cylinder block 53 (cylinder sleeve 55), the cylinder head 52, and the piston 56 via an intake port and an exhaust port, respectively. The saddle-shaped intake valve 62 and the saddle-shaped exhaust valve 63 are each provided with an intake port by valve springs 64 and 65, one end of which is attached to the valve shaft and supported by the retainer, and the other end is supported by the cylinder head 52. And the exhaust port is normally biased in the direction of closing.

  Further, a camshaft 66 for opening and closing the intake valve 62 and the exhaust valve 63 is rotatably disposed in the cylinder head 52. The camshaft 66 is arranged on a cam driven sprocket 67 and a crankshaft 58. A timing chain 69 is wound around the cam drive sprocket 68 provided. Therefore, the camshaft 66 rotates in accordance with the rotation of the crankshaft 58, and the cams 70 and 71 formed on the camshaft 66 push down the intake valve 62 and the exhaust valve 63 via the rocker arms 72 and 73. Open and close intake and exhaust ports. The intake port 60 is provided with an injector 74, and fuel is atomized into the intake port 60 and injected by the injector 74. Further, a spark plug 75 is attached to the cylinder head 52.

  A cam chain tensioner 84 for adjusting the timing of opening and closing the intake valve 62 and the exhaust valve 63 by the cams 70 and 71 by adjusting the tension of the timing chain 69 is attached to the side of the cylinder block 53. .

  In the engine 50 configured as described above, a mixture of the air cleaned by the air cleaner 22 and the fuel injected by the injector 74 is supplied from the intake port 60 to the combustion chamber 59 and compressed by the piston 56 and then ignited. It is ignited by the plug 75 and combusted to become energy for rotating the crankshaft 58 through the piston 56, and then exhausted as exhaust gas from the exhaust port 61 to the outside.

  The crankshaft 58 includes a right crankshaft half body 58a and a left crankshaft half body 58b, and a connecting rod 57 is connected to the crankshaft 57 via a crank pin 76 that is connected to both the crankshaft half bodies 58a and 58b. It is connected. The crankcase 54 that houses the crankshaft 58 includes a right case half 54a and a left case half 54b, and one end of the crankshaft 58 (the journal portion of the right crankshaft half 58a) is provided with a bearing 77. The other end (the journal portion of the left crankshaft half 58b) is supported by the left case half 54b via a bearing 78. Further, an ACG 79 and a radiator fan 85 are disposed at the tip of the journal portion of the right crankshaft half 58a.

  A left side portion of the left case half 54b extends rearward to form a part of the transmission case 80, and a transmission chamber 82 surrounded by a transmission cover 81 attached to the left side surface of the left case half 54b. A transmission 90 is stored. The transmission 90 is attached to the front end of the journal portion of the left crankshaft half 58b extending into the transmission chamber 82 and rotates integrally with the drive pulley 91. The transmission 90 is positioned behind the transmission chamber 80 and the crankshaft 58. A countershaft 92 that extends in parallel and is rotatably mounted, a driven pulley 93 that is mounted so as to be relatively rotatable with respect to the countershaft 92 at a substantially central portion of the countershaft 92, and is mounted and driven at the left end of the countershaft 92. A clutch 94 that engages and disengages the pulley 93 and the counter shaft 92 and a transmission belt (not shown) that is wound around the drive pulley 91 and the driven pulley 93 and transmits the rotation of the drive pulley 91 to the driven pulley 93.

  The drive pulley 91 is fixedly attached to the crankshaft 58 so as to be integrally rotatable. The drive pulley 91 is relatively movable in the axial direction with respect to the fixed pulley half 91a and rotates integrally with the crankshaft 58. The transmission belt is sandwiched between the fixed pulley half 91a and the movable pulley half 91b. On the other hand, the driven pulley 93 is fixed to the countershaft 92 so as to be rotatable relative to the countershaft 92. The driven pulley 93 can move relative to the stationary pulley half 93a in the axial direction and can rotate relative to the countershaft 92. The movable pulley half 93b, and the transmission belt is sandwiched between the fixed pulley half 93a and the movable pulley half 93b. Therefore, by variably setting the pulley widths of the drive pulley 91 and the driven pulley 93, the wrapping radius of the transmission belt around the pulleys 91 and 93 is continuously changed, so that the gear ratio is continuously variable (continuously). Can be controlled.

  In parallel with the counter shaft 92, a rear wheel shaft 96 to which the idle shaft 95 and the rear wheel 25 are attached is rotatably attached, and a gear train attached to the counter shaft 92, the idle shaft 95 and the rear wheel shaft 96 is arranged. The rotational driving force of the countershaft 92 is transmitted to the rear wheel 25 via this. As described above, the output of the engine 50 is transmitted to the crankshaft 58, and after being shifted by the transmission 90, is transmitted to the rear wheel 25.

  In addition, when such a power unit 16 is operated, since it generates heat | fever, it is necessary to cool each part. Therefore, a water jacket 122 that cools the cylinder head 52 by flowing cooling water therein is formed and cooled by the cooling water. The cylinder block 53 protrudes outward at the side. A plurality of cooling fins 86 are formed to release heat generated in the cylinder block 53 from the cooling fins 86, and the transmission case 80 extends forward at the front portion of the transmission case 80. A cooling air introduction passage 83 for taking outside air into the transmission chamber 82 is provided for cooling.

  Next, a cooling water supply device 120 that supplies cooling water into a water jacket 122 formed in the cylinder head 52 to cool the cylinder head 52 will be described with reference to FIGS. The cooling water supply device 120 includes a cooling water pump 125 that pressurizes and discharges the cooling water, a radiator 129 that collects and discharges the cooling water used for cooling by the water jacket 122, and a temperature of the cooling water is a predetermined value. The thermostat 130 is returned to the water jacket 122 without being dissipated by the radiator 129 when the value is less than the value.

  The cooling water pump 125 is attached to one end of a pump shaft 132 that extends substantially parallel to the right crankshaft half 58a, and has an impeller 131 that pressurizes cooling water by being rotated by the pump shaft 132. A pump driven sprocket 133 is attached to the other end of the pump shaft 132. In addition, a pump idle shaft 134 is provided between the pump shaft 132 and the right crankshaft half 58a and extends substantially parallel to the shafts 58a and 132. A pump driven gear 136 that meshes with a pump drive gear 135 coupled to the right crankshaft half 58a is attached to the pump idle shaft 134, and a pump drive sprocket 137 is attached to the pump idler shaft 134 along with the pump drive gear 135. A pump chain 138 is wound around the pump drive sprocket 137 and the pump driven sprocket 133. Thereby, the rotation of the right crankshaft half 58a due to the driving of the engine 50 is transmitted to the pump idle shaft 134 via the pump drive gear 135 and the pump driven gear 136, and the rotation is transmitted from the pump drive sprocket 137 to the pump chain. The pump shaft 132 rotates by being transmitted to the pump driven sprocket 133 via 138, and the cooling water is pressurized and discharged from the discharge port 126 of the cooling water pump 125.

  A water jacket 122 that is a space formed so as to cover the combustion chamber 59 is provided in front of the combustion chamber 59 formed in the cylinder head 52. In addition, the cylinder head 52 has a cooling water outlet portion 121 in which an upper side portion of the water jacket 122 is formed with a cooling water outlet passage 121a communicating with the outside and the water jacket 122 to discharge the cooling water to the outside. ing. In addition, the cylinder head 52 has a cooling water introduction space 123 formed adjacent to the lower rear of the water jacket 122, and the cooling water introduction space 123 is opened on the rear side surface below the cylinder head 52. And communicates with the water jacket 122.

  On the other hand, a cooling water introduction portion 128 that protrudes laterally is formed on the lower side surface of the front portion of the cylinder block 53, and this cooling water introduction portion 128 has an inlet 128a that opens downward. A first passage 140a extending in the direction and a second passage 140b communicating with the first passage 140a and extending forward (hereinafter referred to as “cooling water introduction” together with the first and second passages 140a and 140b). Called passage 140 "). The second passage 140b has a lead-out port 128b opened at the front end surface of the cylinder block 53. When the cylinder head 52 is attached to the cylinder block 53, the second passage 140b has an opening (lead-out port 128b). ) Communicates with the opening of the cooling water introduction space 123 of the cylinder head 52, and the cooling water introduction passage 140 communicates with the water jacket 122. Further, the discharge port 126 of the cooling water pump 125 and the cooling water introduction part 128 formed in the cylinder block 53 are disposed close to each other, and these are connected by a cooling water supply pipe 127.

The thermostat 130 has a first introduction part 141 and a second introduction part 142, and when the temperature of the cooling water flowing from the first and second introduction parts 141 and 142 is below a predetermined temperature, The second introduction unit 142 is closed and the cooling water is discharged from the first introduction unit 141 to the outlet unit 143. When the temperature is higher than a predetermined temperature, the first introduction unit 141 is closed and the second introduction unit 142 is closed. The cooling water is discharged to the derivation unit 143. Further, the thermostat 130 is provided with a valve body 154 whose axis is inclined forward in a side view, and the thermostat 130 has a first thermostat chamber S ₁ communicated with the first introduction part 141 by the valve body 154. And a second thermostat chamber S ₂ communicating with the second introduction part 142.

  A first cooling water pipe 144 is connected to the cooling water outlet portion 121 formed in the cylinder head 52, and the first cooling water pipe 144 is connected to the second cooling water pipe 146 a and the third cooling water at the branch portion 145. Branches to the water pipe 146b. The second cooling water pipe 146 a is connected to the suction hole 147 of the radiator 129, and the third cooling water pipe 146 b is connected to the first introduction part 141 of the thermostat 130. On the other hand, the second introduction portion 142 of the thermostat 130 is connected to a discharge hole 148 of a radiator 129 disposed in the vicinity via a rigid connection pipe 149. The branch portion 145 is formed with a positioning portion 145a for positioning when the first to third cooling water pipes 144, 146a, 146b are attached.

  The housing (thermostat cover 130a) for storing the thermostat 130 is integrally formed with the housing for storing the cooling water pump 125, and the lead-out portion 143 of the thermostat 130 and the inlet 150 of the cooling water pump 125 are directly connected. Has been. Therefore, the thermostat 130 constitutes a part of the cooling water flow path that sends the cooling water to the suction port 150 of the cooling water pump 125, and the flow path through which the cooling water flows can be shortened, and the overall size can be reduced. Moreover, the assembly property of the power unit 16 can be improved by connecting the radiator 129 and the thermostat 130 with the connecting pipe 149.

  According to the cooling water supply device 120 configured as described above, the cooling water discharged from the cooling water pump 125 passes through the cooling water introduction passage 140 of the cooling water introduction portion 128 formed in the cylinder block 53 and is water. It flows into the jacket 122. Then, the cylinder head 52 is cooled and discharged from the cooling water outlet 121 to the outside. The discharged cooling water flows into the suction hole 147 of the radiator 129 or the first introduction part 141 of the thermostat 130. When the temperature of the cooling water is equal to or lower than a predetermined value, the thermostat 130 causes the second introduction part 142 to flow. Therefore, when the temperature of the cooling water is higher than a predetermined value, the first introduction part 141 is closed by the thermostat 130 and the heat is radiated through the radiator 129. After that, the second introduction unit 142 returns to the cooling water pump 125 to circulate.

  As described above, the cooling water intake (cooling water introduction portion 128) for cooling the cylinder head 52 is not formed in the cylinder head 52 but in the cylinder block 53. While improving the design freedom around, the dead space around the cylinder block 53 can be used effectively. As is apparent from FIG. 4 and the like, the cooling water introduction portion 128 is provided in the front end portion of the cylinder block 53, that is, in the vicinity of the cylinder head 52. Therefore, the weight can be reduced and the manufacturing cost can be reduced. Further, the processing of the cooling water introduction passage 140 in the cylinder block 53 is facilitated.

  The cooling water supply device 120 is concentrated on the right side of the power unit 16, and the radiator 129 includes a radiator cover 152 and a radiator outer cover 153 attached to the right end of the right crankcase half 54a. Stored in At this time, the cooling water lead-out portion 121 is formed so as to extend from the cylinder head 52 toward the suction hole 147 of the radiator 129, and therefore, the cooling water pipe (the first water pipe connecting the cooling water lead-out portion 121 and the suction hole 147) The lengths of the cooling water pipe 144 and the second cooling water pipe 146a) can be shortened, and the handling of these cooling water pipes is facilitated.

In addition, by disposing the thermostat 130 below the radiator 129, it is possible to make it difficult for air (bubbles) to stay in the thermostat 130. Furthermore, since the second thermostat chamber S ₂ than the line L ₁ which extends horizontally from an upper end in communication with the first inlet portion 142 below the outlet 148 is disposed, the second thermostat chamber S ₂ in air ( Bubbles) can be made difficult to stay. At this time, by tilting the axis L ₂ of the thermostat 130 with respect to the vertical direction, the height of the thermostat 130 can be shortened, and the position where the air stays in the thermostat 130 can be arbitrarily determined. It is possible to vent the air efficiently by providing a passage for removing air.

  By the way, in the power unit 16 according to the present embodiment, in order to reduce harmful substances contained in the exhaust gas discharged from the engine 50, it is necessary to keep the ratio of air and fuel optimal in accordance with the state of the engine 50. is there. Therefore, an engine control unit (not shown) realizes an optimal air-fuel ratio by controlling the injector 74 and the like from the coolant temperature, the oxygen concentration contained in the exhaust gas, the opening of the throttle, and the like. A water temperature sensor 119 that measures the temperature of the cooling water is formed in the cylinder head 52 and attached to a water temperature sensor mounting hole 119a that communicates with the water jacket 122. The temperature of the cooling water to be discharged from the cooling water outlet 121 is Measured. On the other hand, the O 2 sensor 116 for measuring the oxygen concentration of the exhaust gas is formed in the cylinder head 52 and attached to the O 2 sensor attachment hole 116 a communicating with the exhaust port 61. Therefore, the O2 sensor 116 can reach the activation temperature promptly by the high-temperature exhaust gas, so that it is not necessary to provide a special heater structure and can be made inexpensive.

  The water temperature sensor mounting hole 119a and the O2 sensor mounting hole 116a are concentrated on the same side as the cooling water supply device 120, that is, on the right side of the power unit 16. Further, the axis of the water temperature sensor mounting hole 119a and the O2 sensor mounting hole 116a are formed so as to be substantially parallel to the axis of the cooling water outlet passage 121a. Therefore, when machining the cooling water outlet passage 121a, the water temperature sensor attachment hole 119a, and the O2 sensor attachment hole 116a with respect to the cylinder head 52, there is no need to change the angle of the machining axis, and the machining operation is facilitated. Become. Also, the first cooling water pipe 144, the water temperature sensor 119, and the O2 sensor 116 can be attached in a concentrated manner from one side (right side) of the power unit 16, so that the assembly is facilitated.

  Further, as is clear from FIG. 8 and the like, in the power unit 16 according to the present embodiment, the radiator 129 is disposed so as to be located behind and above the engine 50. Therefore, the axes of the cooling water outlet passage 121a and the like are arranged to extend upward. At this time, since the exhaust port 61 is opened on the lower surface of the cylinder head 52 and the exhaust pipe 23 is disposed below the engine 50, the first cooling water pipe 14, the water temperature sensor 119, and the O2 sensor 116 are connected. Since it can be attached from above, the assembly work can be further facilitated.

  Furthermore, since the seat surface on which the cooling water outlet 121 is formed and the seat surface on which the water temperature sensor mounting hole 119a is formed are on the same plane in the cylinder head 52, the respective seat surfaces can be processed simultaneously. , Processing costs can be reduced.

1 is a side view of a scooter type vehicle to which an engine according to the present invention is attached. It is a top view of a power unit. It is a left view of a power unit. It is a right view of a power unit. It is sectional drawing of a cylinder head. It is a sectional side view of the principal part containing a cooling water supply apparatus. It is a plane sectional view of the important section containing a cooling water supply device. It is sectional drawing of the principal part of the power unit containing a cooling water supply apparatus. It is sectional drawing of the principal part of a cylinder block. It is a front view of a power unit. It is the perspective view which looked at the power unit from the upper part.

Explanation of symbols

2 Body frame (body)
50 Engine 52 Cylinder head 61 Exhaust port 121a Cooling water outlet passage (cooling water discharge hole)
122 Water jacket 116 O2 sensor (exhaust gas sensor)
116a O2 sensor mounting hole (exhaust gas sensor mounting hole)
119 Water temperature sensor 119a Water temperature sensor mounting hole 129 Radiator

Claims (4)

An exhaust port for discharging exhaust gas to the outside, a water jacket to which cooling water is supplied, a cooling water discharge hole for discharging the cooling water from the water jacket, and the exhaust port, the exhaust port in the exhaust port An exhaust gas sensor mounting hole to which an exhaust gas sensor for detecting the oxygen concentration of the exhaust gas is mounted, and a water temperature sensor mounting hole to be connected to the water jacket and to which a water temperature sensor for detecting the temperature of the cooling water in the water jacket is mounted. Having a formed cylinder head,
An engine characterized in that the cooling water discharge hole, the exhaust gas sensor mounting hole, and the water temperature sensor mounting hole are arranged so that axes thereof are substantially parallel to each other.   The cooling water discharge hole, the exhaust gas sensor mounting hole, and the water temperature sensor mounting hole are arranged so that the axis extends laterally and upward when mounted on the vehicle body. The engine according to claim 1. Having a radiator that radiates heat of the cooling water discharged from the water jacket;
The engine according to claim 1, wherein the cooling water discharge hole is arranged so that the axis of the cooling water discharge hole extends toward the radiator. The engine according to claim 1, wherein the seat surface on which the cooling water discharge hole is formed and the seat surface on which the water temperature sensor mounting hole is formed are located on the same plane.

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