Title of Invention	"INTERNAL COMBUSTION ENGINE WITH SENSOR FOR DETECTING OPERATING CONDITIONS"
Abstract	To provide an internal combustion engine mounted on a small-sized vehicle which can protect a sensor mounted on a cylinder in a projecting manner from a flying pebbles or the like without requiring a particular member and a particular mounting operation. [Means for Resolution] An internal combustion engine 20 mounted on a small-sized vehicle 1 mounts a sensor 50 for detecting a driving state on a cylinder 22 which is substantially horizontally arranged in a state that the cylinder is directed frontwardly. Here, the sensor 50 is mounted on a side of the cylinder 22 in a projecting manner, and a vehicle body part 34 is arranged below the sensor 50. [Selected drawing] Fig. 1

Title of Invention

"INTERNAL COMBUSTION ENGINE WITH SENSOR FOR DETECTING OPERATING CONDITIONS"

Abstract

To provide an internal combustion engine mounted on a small-sized vehicle which can protect a sensor mounted on a cylinder in a projecting manner from a flying pebbles or the like without requiring a particular member and a particular mounting operation. [Means for Resolution] An internal combustion engine 20 mounted on a small-sized vehicle 1 mounts a sensor 50 for detecting a driving state on a cylinder 22 which is substantially horizontally arranged in a state that the cylinder is directed frontwardly. Here, the sensor 50 is mounted on a side of the cylinder 22 in a projecting manner, and a vehicle body part 34 is arranged below the sensor 50. [Selected drawing] Fig. 1

Full Text	SPECIFICATION Internal Combustion Engine The present invention relates to an internal combustion engine mounted on a small-sized vehicle such as a motorcycle or a three-wheeled vehicle, and more particularly to an internal combustion engine having a sensor for detecting operating conditions of the engine, on an engine cylinder arranged substantially horizontally. In an internal combustion engine mounted on a motorcycle and having a horizontally oriented cylinder, there has been known an engine in which a lubricant oil temperature sensor is provided at a lower portion of the cylinder (see JP-A-2004-293348). The oil temperature sensor disclosed in JP-A-2004-293348 is mounted on a lower portion of the cylinder obliquely upwardly from the left side to the right side, and a portion of the oil temperature sensor projects obliquely downwardly. Therefore, there exists a possibility that mud water, flying pebbles and the like splashed by the front wheel of the vehicle hit on the oil temperature sensor, and hence the oil temperature sensor is smeared or damaged. To cope with such a situation, a front portion of the oil temperature sensor had to be covered with a special sensor cover. By mounting such special dedicated sensor cover on the internal combustion engine, the oil temperature sensor could be protected from the flying pebbles and the like. Accordingly, it was necessary to manufacture the dedicated sensor cover and to mount the sensor cover on the internal combustion engine, and hence the number of parts was increased and a forming operation and a mounting operation for mounting the sensor cover on the internal combustion engine were required, thus pushing up the manufacturing costs. The present invention has been made under such circumferences and it is an object of the present invention to provide an internal combustion engine mounted on a small-sized vehicle, which can protect the sensor mounted on the cylinder in a projecting manner from flying pebbles and the like without requiring a particular member and a particular mounting operation. To achieve the above-mentioned object, the present invention provides an internal combustion engine mounted on a small-sized vehicle, having a cylinder which is substantially horizontally arranged so as to be directed forwardly of the vehicle, and a sensor provided on the engine to detect operating conditions of the engine: wherein the sensor is mounted on a side of the cylinder in a projecting manner; and a component part of the vehicle is arranged below the sensor. According to the invention, the component part receives flying pebbles and the like which jump up from the ground during travel of the vehicle, thus protecting the sensor. Accordingly, a special protection member for protecting the sensor from the flying pebbles and the like is not required, and the mounting operation for the special protection member becomes unnecessary, whereby it is possible to realize a reduction of the manufacturing costs. The component part of vehicle may be an exhaust pipe of the engine, extending below the sensor. In this case, the exhaust pipe receives pebbles and the like which jump up from the ground during travel of the vehicle, thus protecting the sensor. Preferably, a catalyst device constituting a portion of the exhaust pipe is arranged below the sensor. In this case, the catalyst device having a largest width in the region of the exhaust pipes can surely protect the sensor from the flying pebbles and the like. The component part may be a frame part of the vehicle. In this case, the vehicle body frame part receives the flying pebbles and the like which jump up from the ground during travel of the vehicle, thus protecting the sensor. The frame part may be one of a down frame and a cross member extended between a pair of left and right down frames. In this case, the down frame or the cross member can protect the sensor from the flying pebbles and the like without using a special protection member. A cooling fin constituting a portion of the cylinder may be formed at a position in front of the sensor. In this case, even when oncoming flying pebbles and the like are present, the cooling fin of the cylinder receives the oncoming flying pebbles and so on without using a special protection member.thus protecting the sensor. The cooling fin may be formed in an L-shape extending from a side surface to a lower surface of the cylinder. In this case, it is possible to surely protect the sensor from oncoming flying pebbles and the like by maintaining high strength of the cooling fin. The sensor may be mounted on the side of the cylinder so as to project from the side of the cylinder substantially horizontally in parallel to the ground. In this case, the sensor can be easily mounted on the cylinder. The sensor may be mounted on a lower portion of the cylinder in a manner accessible from below. In this case, the sensor can be easily mounted from below on the lower portion of the cylinder. The present invention will now be described in detail with reference to the accompanying drawings, in which: Fig. 1 is a side view of a motorcycle which mounts an internal combustion engine according to an embodiment of the present invention; Fig. 2 is a partial plan view of the motorcycle; Fig. 3 is a side view of an essential part of the internal combustion engine with a part omitted; Fig. 4 is a front view of a cylinder block as viewed from a joining surface with a cylinder head; Fig. 5 is a side view of a motorcycle according to another embodiment; and Fig. 6 is a bottom surface view of an essential part of the motorcycle according to another embodiment as viewed from below. A first embodiment of the invention will be described with reference to Figs. 1 to 4. Fig. 1 shows, in side view, a motorcycle 1 on which is mounted an internal combustion engine 20 of the present invention. The motorcycle 1 has a vehicle body frame which is constituted as follows. A main frame 3 extends in the rearward and obliquely downward direction from a head pipe 2, a pair of left and right pivot plates 4 extend vertically downwardly and is mounted on a rear end portion of the main frame 3, a pair of left and right rear frames 5 extends in the rearward and obliquely upward direction from a rear portion of the main frame 3, and sub-frames 6 are extended between the pivot plates 4 and the rear frames 5, respectively. A front wheel 9 is rotatably supported on the lower end of a front fork 8 which is mounted on the head pipe 2 in a state that the front fork 8 is steerable by a steering handle bar 7. On the other hand, swing arms 11 are connected to the pivot plates 4, respectively, in a vertically swingable manner in such a state that each swing arm 11 has a front end thereof pivotally supported on a pivot shaft 10, and a rear wheel 12 is rotatably supported on the rear end of the swing arm 11. A rear cushion 13 is interposed between each swing arm 11 and each upper rear frame 5. A fuel tank 14 is mounted on front portions of the pair of left and right rear frames 5, a container box 15 is supported on parts in the range from the fuel tank 14 to rear portions of the rear frames 5, and a seat 16 is mounted on the container box 15. The seat 16 can be opened and closed. An internal combustion engine 20 is supported in a suspended manner on the pivot plates 4 and on a downwardly projecting engine hanger 17 which is mounted on the main frame 3 at a position slightly behind the center of the main frame 3. The internal combustion engine 20 is a four-stroke-cycle single-cylinder internal combustion engine. The internal combustion engine 20 is mounted on the vehicle body frame in a state that the cylinder of the internal combustion engine 20 is substantially horizontally directed in the frontward direction. That is, a cylinder block 22, a cylinder head 23 and a cylinder head cover 24 are arranged in this order frontwardly from a crank case 21. An output shaft 25 extends leftwardly with respect to the motor cycle from a transmission chamber at a rear portion of the crank case 21, a drive sprocket wheel 26 is secured to an end portion of the output shaft 25, a drive chain 28 is extended between the drive sprocket wheel 26 and a driven sprocket wheel 27 which is fitted on an axle of the rear wheel 12, so that the drive power of the internal combustion engine 20 is transmitted to the rear wheel 12. An air intake pipe 30 extends upwardly from the upper surface of the cylinder head 23 which is arranged forwardly and substantially horizontally, and the intake pipe 30 is connected to an air cleaner 32 which is mounted on the main frame 3 by way of a throttle body 31 incorporating an injector therein. As shown in Fig. 1 and Fig.2 which shows in plan view an essential part of the internal combustion engine 20, an exhaust pipe 33 extends downwardly from the lower surface of the cylinder head 23, is bent forwardly, and thereafter is curved leftwardly by 180 degrees, then extending rearwardly. The exhaust pipe 33 extends rearwardly along the lower surface of the crank case 21. A catalyst device 34 is connected to the exhaust pipe 33 at an obliquely leftward and downward position of the cylinder head 23 and the cylinder block 22 and in front of the crank case 21. The exhaust pipe 33 is connected to a muffler 35 which is arranged behind the crank case 21. The muffler 35 is constituted of a enlarged-width front portion 35a arranged between the crank case 21 and the rear wheel 12 and a reduced-width rear portion 35b extending rearwardly along the right side of the rear wheel 12 from the enlarged-width front portion 35a (see Fig. 2). The muffler 35 is supported on the pivot plates 4. and the exhaust pipe 33 is connected to a left-side portion of the front-surface of the enlarged-width front portion 35a. The handle bar 7 is covered with a handle cover 60, the front portion of the head pipe 2 is covered with a front cover 61, the portion of the main frame 3 and both the left and right side portions thereof are covered with a leg shield 62, and peripheral and lower portions of the container box 15 are covered with a body cover 63 . Further, a front fender 64 extends from the upper portion to the rear portion of the front wheel 9 to cover the front wheel 9, while a rear fender 65 covers the rear wheel 12 from obliquely above. Referring to Fig.3, the internal combustion engine 20 of the present invention adopts an OHC chain valve actuating mechanism driving system, and a cam chain 42 is used to transmit the rotation of an engine crank shaft 40 to a cam shaft 41 which is mounted on the cylinder head 23. A power transmission mechanism to the valve actuating mechanism using the cam chain 42 is provided on a left side portion of the internal combustion engine 20. Fig. 4 shows a front view of the cylinder block 22 as viewed from the side thereof at which the cylinder head 23 is attached to the cylinder block 22. Here, in the left side (in Fig. 4, right side) of a cylinder bore 22a, a cam chain chamber 43 is formed in a vertically-elongated, substantially rectangular shape . Here, the cam chain chamber 43 is also formed continuously in the cylinder head cover 24. The cam chain 42 which passes through the cam chain chamber 43 is extended between a drive sprocket wheel 40a fitted on the crank shaft 40 and a driven sprocket wheel 4la fitted on the cam shaft 41. Along the cam chain 42 on the side (lower side) pulled by the drive sprocket 40a, a fixed chain guide 45 is provided which supports from below the lower extension of the cam chain 42 and guides the lower extension, while to the upper extension of the cam chain 42 on the side (upper side) pushed out by the drive sprocket 40a, a cam chain tensioner 46 is provided which gives tension to the cam chain 42 from above. Below the chain guide 45 of the cam chain chamber 43, an oil return channel or groove 43a is formed. As shown in Fig.3, a mounting boss 22b having a through hole is formed on a lower rear portion of the left side surface of the cylinder block 22 , and a lubricant oil temperature sensor 50 is substantially horizontally inserted into the through hole of the mounting boss 22b from the left side thereof. The oil temperature sensor 50 (a sensor for detecting the operating condition of the engine) has a right half portion (left half inner portion as viewed in Fig.4) thereof inserted into the through hole. The oil temperature sensor 50 has a temperature detecting portion 50a formed on the inner distal end thereof projecting into the oil returning channel 43a. The oil temperature sensor 50 has a left half portion (right half outer portion as viewed in Fig.4) thereof mounted in a left side wall of the cylinder block 22 in a state in which the left half portion projects leftwardly substantially horizontally in parallel to the ground. Therefore, in the internal combustion engine 20 in which the cylinder block 22 is substantially horizontally arranged, the oil temperature sensor 50 used in the present invention can detect oil temperature in the oil return channel 43a through which all return oil flows . This arrangement makes it possible to measure the oil temperature accurately. On surfaces of the cylinder block 22, a plurality of projecting cooling fins 22f are formed, the cooling fins 22F being also formed on an exposed front part of the left half portion of the oil temperature sensor 50. The cooling fins 22F are formed in an L-shape from the left side surface to the lower surface of the cylinder block 22 and hence, the strength of the cooling fins 22F is increased (see Fig. 4). It is possible to protect the oil temperature sensor 50 from oncoming flying pebbles, foreign substances and the like, by the cooling fins 22F which are formed on the portion right in front of the oil temperature sensor 50. Below the oil temperature sensor 50 is arranged the catalyst device 34 which constitutes a portion of the exhaust pipe 33.The catalyst device 34 is provided in a portion of the exhaust pipe 33 where the diameter of the exhaust pipe 33 is largely increased, and the oil temperature sensor 50 is disposed above the catalyst device 34, which has an enlarged lateral width and a large longitudinal length. Due to such a configuration, the catalyst device 34 protects the oil temperature sensor 50 by receiving the flying pebbles and the like which come jumpingly from the ground particularly due to the rotation of the front wheel 9 during travel of the motorcycle. Thus, it is possible to protect the oil temperature sensor 50. For this reason, particular protection measure for protecting the oil temperature sensor 50 from the flying pebbles and the like are unnecessary, and the mounting operation of protection parts also becomes unnecessary, whereby production costs are reduced. The leg shield 62 is disposed at a position on a lef twardly and oblique front side of the oil temperature sensor 50 which projects leftwardly from the cylinder head 23 (see Figs. 1 and 2), and hence it is possible to protect the oil temperature sensor 50 from obliquely oncoming flying pebbles and the like, by the leg shield 62. Next, a second embodiment in which the same internal combustion engine 20 is mounted on a motorcycle 80 having the vehicle body structure different from the vehicle body structure of the motorcycle 1 will be described in conjunction with Figs. 5 and 6. The motorcycle 80 is a saddle-riding type vehicle, wherein a main frame 82 extends rearwardly from a head pipe 81 and, at the same time, a pair of down frames 83 extend obliquely downwardly with a structure divided into the left and right portions. The down frames 83 are bent at lower ends thereof and extend rearwardly, rear ends of the down frames 83 are connected to rearwardly-curved lower ends of a pair of left and right center frames 84 which extend obliquely downward from a middle portion of the main frame 82. A pair of left and right seat rails 85 extends rearward from the main frame 82, and side frames 86 are extended between curved portions of the center frames 84 and the seat rails 85. A front wheel 88 is rotatably supported on the lower end of a front fork 87 which is steerablly supported on the head pipe 81, swing arms 90 are mounted on pivot plates 89 which are mounted on the curved portion of the center frame 84 in a rockable manner. Each of the swing arms 90 has a front end thereof pivotally supported on the pivot plate 89, and a rear wheel 91 is rot at ably supported on the rear ends of the swing arms 90. A rear cushion 92 is interposed between the rear portion of each swing arm 90 and the upper seat rail 85. A fuel tank 93 is supported on the main frame 82, and a seat 94 is mounted on the seat rails 85 which are arranged behind the fuel tank 93. The internal combustion engine 20 (indicated by the same numeral as in the first embodiment) which has the same construction as that in the first embodiment is supported on an engine hanger 93 and the pivot plate 89 which are mounted on the center frame 84 in a projecting manner. An air intake pipe 95 extends upwardly from the cylinder head 23 of the internal combustion engine 20 and extends further rearwardly by way of a throttle body 96. The intake pipe 95 is connected to an air cleaner 97 which is mounted below front portions of the seat rails 85. An exhaust pipe 98 extends downwardly from the cylinder head 23 on the right side of the motorcycle and then is bent, extending further rearwardly along the lower surface of the crank case 21. The exhaust pipe 98 is connected to a longitudinally elongated muffler 99 which is mounted on the right side of the rear wheel 91. On the internal combustion engine 20 which is mounted on the motorcycle 80 described above, an oil temperature sensor 50 is mounted in a projecting manner on a lower portion of the cylinder block 22 along the left side surface of the cylinder block 22, in such a state that the oil temperature sensor 50 is directed in the leftward and obliquely downward direction. Since the oil temperature sensor 50 is mounted from the oblique lower side, the oil temperature sensor 50 is accessible from below and can be easily assembled and mounted in position. Here, the oil temperature sensor 50 may be mounted in a state in which the oil temperature sensor 50 projects substantially horizontally in parallel to the ground. Cooling fins 22F are arranged at a position right in front of the oil temperature sensor 50, and hence the cooling fins F22 can protect the oil temperature sensor 50 from oncoming flying pebbles, foreign substances and the like. At an obliquely frontward position below the oil temperature sensor 50, a cross pipe 100 are extended between the pair of left and right down frames 83, and a cross plate 101 is extended between the pair of left and right down frames 83 behind the cross pipe 100. The cross plate 101 has a front end thereof connected to the cross pipe 100. With such a configuration, the cross plate 101 covers the oil temperature sensor 50 from below, the cross plate 101 and the cross pipe 100 receive the flying pebbles and the like which are jumped from the ground particularly due to the rotation of the front wheel 9 during travel of the motor cycle, whereby it is possible to protect the oil temperature sensor 50. For this reason, particular protection measures for protecting the oil temperature sensor 50 from the flying pebbles and the like are unnecessary, and the mounting operation of protection parts also becomes unnecessary, so that it is possible to realize the reduction of manufacturing costs . As described above, the oil temperature sensor 50 can be protected from the flying pebbles and the like by the cross plate 101, the cross pipe 100 and the cooling fins 22F. However, to achieve the complete protection, a guard member 110 shown in Figs. 5 and 6 may be preliminarily provided for preventing the flying pebbles and the like from jumping into the space between the cylinder block 22 and the cross pipe 100. The guard member 110 has a proximal end thereof fixedly secured to the lower surface of the cylinder block 22 using a bolt 111. The guard member 110 extends rearwardly and obliquely downwardly from the proximal end and projects into the space defined between the oil temperature sensor 50 and the cross pipe 100. Accordingly, the guard member 110 receives the oncoming flying pebbles and the like which jump into the space between the cylinder block 22 and the cross pipe 100, thus preventing the oncoming flying pebbles and the like from intruding into further rear portion of the space, and hence it is possible to reliably protect the oil temperature sensor 50. The guard member 110 is a small member, and hence a mounting of the guard member 110 is easy. CLAIMS: 1. An internal combustion engine mounted on a small-sized vehicle, having a cylinder which is substantially horizontally arranged so as to be directed forwardly of the vehicle, and a sensor provided on the engine to detect operating conditions of the engine: wherein the sensor is mounted on a side of the cylinder in a projecting manner; and a component part of the vehicle is arranged below the sensor. 2. The internal combustion engine as claimed in claim 1, wherein the component part of vehicle is an exhaust pipe of the engine, extending below the sensor. 3. The internal combustion engine as claimed in claim 2, wherein a catalyst device constituting a portion of the exhaust pipe is arranged below the sensor. 4. The internal combustion engine as claimed in claim I, wherein the component part is a frame part of the vehicle. 5. The internal combustion engine as claimed in claim 4, wherein the frame part is one of a down frame and a cross member extended between a pair of left and right down frames. 6. The internal combustion engine as claimed in any one of claims 1 to 5, wherein a cooling fin constituting a portion of the cylinder is formed at a position in front of the sensor. 7. The internal combustion engine as claimed in claim 6, wherein the cooling fin is formed in an L-shape extending from a side surface to a lower surface of the cylinder. 8. The internal combustion engine as claimed in claim 1, wherein the sensor is mounted on the side of the cylinder so as to project from the side of the cylinder substantially horizontally in parallel to the ground. 9. The internal combustion engine as claimed in claim 1, wherein the sensor is mounted on a lower portion of the cylinder in a manner accessible from below.

Full Text

SPECIFICATION
Internal Combustion Engine
The present invention relates to an internal combustion engine mounted on a small-sized vehicle such as a motorcycle or a three-wheeled vehicle, and more particularly to an internal combustion engine having a sensor for detecting operating conditions of the engine, on an engine cylinder arranged substantially horizontally.
In an internal combustion engine mounted on a motorcycle and having a horizontally oriented cylinder, there has been known an engine in which a lubricant oil temperature sensor is provided at a lower portion of the cylinder (see JP-A-2004-293348).
The oil temperature sensor disclosed in JP-A-2004-293348 is mounted on a lower portion of the cylinder obliquely upwardly from the left side to the right side, and a portion of the oil temperature sensor projects obliquely downwardly. Therefore, there exists a possibility that mud water, flying pebbles and the like splashed by the front wheel of the vehicle hit on the oil temperature sensor, and hence the oil temperature sensor is smeared or damaged.
To cope with such a situation, a front portion of the oil temperature sensor had to be covered with a special sensor

cover. By mounting such special dedicated sensor cover on the internal combustion engine, the oil temperature sensor could be protected from the flying pebbles and the like.
Accordingly, it was necessary to manufacture the dedicated sensor cover and to mount the sensor cover on the internal combustion engine, and hence the number of parts was increased and a forming operation and a mounting operation for mounting the sensor cover on the internal combustion engine were required, thus pushing up the manufacturing costs.
The present invention has been made under such circumferences and it is an object of the present invention to provide an internal combustion engine mounted on a small-sized vehicle, which can protect the sensor mounted on the cylinder in a projecting manner from flying pebbles and the like without requiring a particular member and a particular mounting operation.
To achieve the above-mentioned object, the present invention provides an internal combustion engine mounted on a small-sized vehicle, having a cylinder which is substantially horizontally arranged so as to be directed forwardly of the vehicle, and a sensor provided on the engine to detect operating conditions of the engine: wherein the sensor is mounted on a side of the cylinder in a projecting manner; and a component part of the vehicle is arranged below the sensor.
According to the invention, the component part receives

flying pebbles and the like which jump up from the ground during travel of the vehicle, thus protecting the sensor. Accordingly, a special protection member for protecting the sensor from the flying pebbles and the like is not required, and the mounting operation for the special protection member becomes unnecessary, whereby it is possible to realize a reduction of the manufacturing costs.
The component part of vehicle may be an exhaust pipe of the engine, extending below the sensor. In this case, the exhaust pipe receives pebbles and the like which jump up from the ground during travel of the vehicle, thus protecting the sensor.
Preferably, a catalyst device constituting a portion of the exhaust pipe is arranged below the sensor. In this case, the catalyst device having a largest width in the region of the exhaust pipes can surely protect the sensor from the flying pebbles and the like.
The component part may be a frame part of the vehicle. In this case, the vehicle body frame part receives the flying pebbles and the like which jump up from the ground during travel of the vehicle, thus protecting the sensor.
The frame part may be one of a down frame and a cross member extended between a pair of left and right down frames. In this case, the down frame or the cross member can protect the sensor from the flying pebbles and the like without using

a special protection member.
A cooling fin constituting a portion of the cylinder may be formed at a position in front of the sensor. In this case, even when oncoming flying pebbles and the like are present, the cooling fin of the cylinder receives the oncoming flying pebbles and so on without using a special protection member.thus protecting the sensor.
The cooling fin may be formed in an L-shape extending from a side surface to a lower surface of the cylinder. In this case, it is possible to surely protect the sensor from oncoming flying pebbles and the like by maintaining high strength of the cooling fin.
The sensor may be mounted on the side of the cylinder so as to project from the side of the cylinder substantially horizontally in parallel to the ground. In this case, the sensor can be easily mounted on the cylinder.
The sensor may be mounted on a lower portion of the cylinder in a manner accessible from below. In this case, the sensor can be easily mounted from below on the lower portion of the cylinder.
The present invention will now be described in detail with reference to the accompanying drawings, in which:
Fig. 1 is a side view of a motorcycle which mounts an internal combustion engine according to an embodiment of the present invention;

Fig. 2 is a partial plan view of the motorcycle;
Fig. 3 is a side view of an essential part of the internal combustion engine with a part omitted;
Fig. 4 is a front view of a cylinder block as viewed from a joining surface with a cylinder head;
Fig. 5 is a side view of a motorcycle according to another embodiment; and
Fig. 6 is a bottom surface view of an essential part of the motorcycle according to another embodiment as viewed from below.
A first embodiment of the invention will be described with reference to Figs. 1 to 4.
Fig. 1 shows, in side view, a motorcycle 1 on which is mounted an internal combustion engine 20 of the present invention.
The motorcycle 1 has a vehicle body frame which is constituted as follows. A main frame 3 extends in the rearward and obliquely downward direction from a head pipe 2, a pair of left and right pivot plates 4 extend vertically downwardly and is mounted on a rear end portion of the main frame 3, a pair of left and right rear frames 5 extends in the rearward and obliquely upward direction from a rear portion of the main frame 3, and sub-frames 6 are extended between the pivot plates 4 and the rear frames 5, respectively.
A front wheel 9 is rotatably supported on the lower end

of a front fork 8 which is mounted on the head pipe 2 in a state that the front fork 8 is steerable by a steering handle bar 7.
On the other hand, swing arms 11 are connected to the pivot plates 4, respectively, in a vertically swingable manner in such a state that each swing arm 11 has a front end thereof pivotally supported on a pivot shaft 10, and a rear wheel 12 is rotatably supported on the rear end of the swing arm 11. A rear cushion 13 is interposed between each swing arm 11 and each upper rear frame 5.
A fuel tank 14 is mounted on front portions of the pair of left and right rear frames 5, a container box 15 is supported on parts in the range from the fuel tank 14 to rear portions of the rear frames 5, and a seat 16 is mounted on the container box 15. The seat 16 can be opened and closed.
An internal combustion engine 20 is supported in a suspended manner on the pivot plates 4 and on a downwardly projecting engine hanger 17 which is mounted on the main frame 3 at a position slightly behind the center of the main frame 3. The internal combustion engine 20 is a four-stroke-cycle single-cylinder internal combustion engine.
The internal combustion engine 20 is mounted on the vehicle body frame in a state that the cylinder of the internal combustion engine 20 is substantially horizontally directed in the frontward direction. That is, a cylinder block 22, a

cylinder head 23 and a cylinder head cover 24 are arranged in this order frontwardly from a crank case 21.
An output shaft 25 extends leftwardly with respect to the motor cycle from a transmission chamber at a rear portion of the crank case 21, a drive sprocket wheel 26 is secured to an end portion of the output shaft 25, a drive chain 28 is extended between the drive sprocket wheel 26 and a driven sprocket wheel 27 which is fitted on an axle of the rear wheel 12, so that the drive power of the internal combustion engine 20 is transmitted to the rear wheel 12.
An air intake pipe 30 extends upwardly from the upper surface of the cylinder head 23 which is arranged forwardly and substantially horizontally, and the intake pipe 30 is connected to an air cleaner 32 which is mounted on the main frame 3 by way of a throttle body 31 incorporating an injector therein.
As shown in Fig. 1 and Fig.2 which shows in plan view an essential part of the internal combustion engine 20, an exhaust pipe 33 extends downwardly from the lower surface of the cylinder head 23, is bent forwardly, and thereafter is curved leftwardly by 180 degrees, then extending rearwardly. The exhaust pipe 33 extends rearwardly along the lower surface of the crank case 21. A catalyst device 34 is connected to the exhaust pipe 33 at an obliquely leftward and downward position of the cylinder head 23 and the cylinder block 22 and in front

of the crank case 21. The exhaust pipe 33 is connected to a muffler 35 which is arranged behind the crank case 21.
The muffler 35 is constituted of a enlarged-width front portion 35a arranged between the crank case 21 and the rear wheel 12 and a reduced-width rear portion 35b extending rearwardly along the right side of the rear wheel 12 from the enlarged-width front portion 35a (see Fig. 2). The muffler 35 is supported on the pivot plates 4. and the exhaust pipe 33 is connected to a left-side portion of the front-surface of the enlarged-width front portion 35a.
The handle bar 7 is covered with a handle cover 60, the front portion of the head pipe 2 is covered with a front cover 61, the portion of the main frame 3 and both the left and right side portions thereof are covered with a leg shield 62, and peripheral and lower portions of the container box 15 are covered with a body cover 63 . Further, a front fender 64 extends from the upper portion to the rear portion of the front wheel 9 to cover the front wheel 9, while a rear fender 65 covers the rear wheel 12 from obliquely above.
Referring to Fig.3, the internal combustion engine 20 of the present invention adopts an OHC chain valve actuating mechanism driving system, and a cam chain 42 is used to transmit the rotation of an engine crank shaft 40 to a cam shaft 41 which is mounted on the cylinder head 23. A power transmission mechanism to the valve actuating mechanism using the cam chain

42 is provided on a left side portion of the internal combustion
engine 20.
Fig. 4 shows a front view of the cylinder block 22 as viewed from the side thereof at which the cylinder head 23 is attached to the cylinder block 22. Here, in the left side (in Fig. 4, right side) of a cylinder bore 22a, a cam chain chamber
43 is formed in a vertically-elongated, substantially
rectangular shape . Here, the cam chain chamber 43 is also formed
continuously in the cylinder head cover 24.
The cam chain 42 which passes through the cam chain chamber 43 is extended between a drive sprocket wheel 40a fitted on the crank shaft 40 and a driven sprocket wheel 4la fitted on the cam shaft 41.
Along the cam chain 42 on the side (lower side) pulled by the drive sprocket 40a, a fixed chain guide 45 is provided which supports from below the lower extension of the cam chain 42 and guides the lower extension, while to the upper extension of the cam chain 42 on the side (upper side) pushed out by the drive sprocket 40a, a cam chain tensioner 46 is provided which gives tension to the cam chain 42 from above. Below the chain guide 45 of the cam chain chamber 43, an oil return channel or groove 43a is formed.
As shown in Fig.3, a mounting boss 22b having a through hole is formed on a lower rear portion of the left side surface of the cylinder block 22 , and a lubricant oil temperature sensor

50 is substantially horizontally inserted into the through hole of the mounting boss 22b from the left side thereof.
The oil temperature sensor 50 (a sensor for detecting the operating condition of the engine) has a right half portion (left half inner portion as viewed in Fig.4) thereof inserted into the through hole. The oil temperature sensor 50 has a temperature detecting portion 50a formed on the inner distal end thereof projecting into the oil returning channel 43a. The oil temperature sensor 50 has a left half portion (right half outer portion as viewed in Fig.4) thereof mounted in a left side wall of the cylinder block 22 in a state in which the left half portion projects leftwardly substantially horizontally in parallel to the ground.
Therefore, in the internal combustion engine 20 in which the cylinder block 22 is substantially horizontally arranged, the oil temperature sensor 50 used in the present invention can detect oil temperature in the oil return channel 43a through which all return oil flows . This arrangement makes it possible to measure the oil temperature accurately.
On surfaces of the cylinder block 22, a plurality of projecting cooling fins 22f are formed, the cooling fins 22F being also formed on an exposed front part of the left half portion of the oil temperature sensor 50. The cooling fins 22F are formed in an L-shape from the left side surface to the lower surface of the cylinder block 22 and hence, the strength of

the cooling fins 22F is increased (see Fig. 4).
It is possible to protect the oil temperature sensor 50 from oncoming flying pebbles, foreign substances and the like, by the cooling fins 22F which are formed on the portion right in front of the oil temperature sensor 50.
Below the oil temperature sensor 50 is arranged the catalyst device 34 which constitutes a portion of the exhaust pipe 33.The catalyst device 34 is provided in a portion of the exhaust pipe 33 where the diameter of the exhaust pipe 33 is largely increased, and the oil temperature sensor 50 is disposed above the catalyst device 34, which has an enlarged lateral width and a large longitudinal length.
Due to such a configuration, the catalyst device 34 protects the oil temperature sensor 50 by receiving the flying pebbles and the like which come jumpingly from the ground particularly due to the rotation of the front wheel 9 during travel of the motorcycle. Thus, it is possible to protect the oil temperature sensor 50.
For this reason, particular protection measure for protecting the oil temperature sensor 50 from the flying pebbles and the like are unnecessary, and the mounting operation of protection parts also becomes unnecessary, whereby production costs are reduced.
The leg shield 62 is disposed at a position on a lef twardly and oblique front side of the oil temperature sensor 50 which

projects leftwardly from the cylinder head 23 (see Figs. 1 and 2), and hence it is possible to protect the oil temperature sensor 50 from obliquely oncoming flying pebbles and the like, by the leg shield 62.
Next, a second embodiment in which the same internal combustion engine 20 is mounted on a motorcycle 80 having the vehicle body structure different from the vehicle body structure of the motorcycle 1 will be described in conjunction with Figs. 5 and 6.
The motorcycle 80 is a saddle-riding type vehicle, wherein a main frame 82 extends rearwardly from a head pipe 81 and, at the same time, a pair of down frames 83 extend obliquely downwardly with a structure divided into the left and right portions.
The down frames 83 are bent at lower ends thereof and extend rearwardly, rear ends of the down frames 83 are connected to rearwardly-curved lower ends of a pair of left and right center frames 84 which extend obliquely downward from a middle portion of the main frame 82.
A pair of left and right seat rails 85 extends rearward from the main frame 82, and side frames 86 are extended between curved portions of the center frames 84 and the seat rails 85.
A front wheel 88 is rotatably supported on the lower end of a front fork 87 which is steerablly supported on the head pipe 81, swing arms 90 are mounted on pivot plates 89 which

are mounted on the curved portion of the center frame 84 in a rockable manner. Each of the swing arms 90 has a front end thereof pivotally supported on the pivot plate 89, and a rear wheel 91 is rot at ably supported on the rear ends of the swing arms 90.
A rear cushion 92 is interposed between the rear portion of each swing arm 90 and the upper seat rail 85.
A fuel tank 93 is supported on the main frame 82, and a seat 94 is mounted on the seat rails 85 which are arranged behind the fuel tank 93.
The internal combustion engine 20 (indicated by the same numeral as in the first embodiment) which has the same construction as that in the first embodiment is supported on an engine hanger 93 and the pivot plate 89 which are mounted on the center frame 84 in a projecting manner.
An air intake pipe 95 extends upwardly from the cylinder head 23 of the internal combustion engine 20 and extends further rearwardly by way of a throttle body 96. The intake pipe 95 is connected to an air cleaner 97 which is mounted below front portions of the seat rails 85.
An exhaust pipe 98 extends downwardly from the cylinder head 23 on the right side of the motorcycle and then is bent, extending further rearwardly along the lower surface of the crank case 21. The exhaust pipe 98 is connected to a longitudinally elongated muffler 99 which is mounted on the

right side of the rear wheel 91.
On the internal combustion engine 20 which is mounted on the motorcycle 80 described above, an oil temperature sensor 50 is mounted in a projecting manner on a lower portion of the cylinder block 22 along the left side surface of the cylinder block 22, in such a state that the oil temperature sensor 50 is directed in the leftward and obliquely downward direction.
Since the oil temperature sensor 50 is mounted from the oblique lower side, the oil temperature sensor 50 is accessible from below and can be easily assembled and mounted in position.
Here, the oil temperature sensor 50 may be mounted in a state in which the oil temperature sensor 50 projects substantially horizontally in parallel to the ground.
Cooling fins 22F are arranged at a position right in front of the oil temperature sensor 50, and hence the cooling fins F22 can protect the oil temperature sensor 50 from oncoming flying pebbles, foreign substances and the like.
At an obliquely frontward position below the oil temperature sensor 50, a cross pipe 100 are extended between the pair of left and right down frames 83, and a cross plate 101 is extended between the pair of left and right down frames 83 behind the cross pipe 100. The cross plate 101 has a front end thereof connected to the cross pipe 100.
With such a configuration, the cross plate 101 covers the oil temperature sensor 50 from below, the cross plate 101

and the cross pipe 100 receive the flying pebbles and the like which are jumped from the ground particularly due to the rotation of the front wheel 9 during travel of the motor cycle, whereby it is possible to protect the oil temperature sensor 50.
For this reason, particular protection measures for protecting the oil temperature sensor 50 from the flying pebbles and the like are unnecessary, and the mounting operation of protection parts also becomes unnecessary, so that it is possible to realize the reduction of manufacturing costs .
As described above, the oil temperature sensor 50 can be protected from the flying pebbles and the like by the cross plate 101, the cross pipe 100 and the cooling fins 22F. However, to achieve the complete protection, a guard member 110 shown in Figs. 5 and 6 may be preliminarily provided for preventing the flying pebbles and the like from jumping into the space between the cylinder block 22 and the cross pipe 100.
The guard member 110 has a proximal end thereof fixedly secured to the lower surface of the cylinder block 22 using a bolt 111. The guard member 110 extends rearwardly and obliquely downwardly from the proximal end and projects into the space defined between the oil temperature sensor 50 and the cross pipe 100.
Accordingly, the guard member 110 receives the oncoming flying pebbles and the like which jump into the space between

the cylinder block 22 and the cross pipe 100, thus preventing the oncoming flying pebbles and the like from intruding into further rear portion of the space, and hence it is possible to reliably protect the oil temperature sensor 50.
The guard member 110 is a small member, and hence a mounting of the guard member 110 is easy.

CLAIMS:
1. An internal combustion engine mounted on a small-sized
vehicle, having a cylinder which is substantially horizontally
arranged so as to be directed forwardly of the vehicle, and
a sensor provided on the engine to detect operating conditions
of the engine:
wherein the sensor is mounted on a side of the cylinder in a projecting manner; and
a component part of the vehicle is arranged below the sensor.
2. The internal combustion engine as claimed in claim
1, wherein the component part of vehicle is an exhaust pipe
of the engine, extending below the sensor.
3. The internal combustion engine as claimed in claim
2, wherein a catalyst device constituting a portion of the
exhaust pipe is arranged below the sensor.
4. The internal combustion engine as claimed in claim
I, wherein the component part is a frame part of the vehicle.
5. The internal combustion engine as claimed in claim
4, wherein the frame part is one of a down frame and a cross
member extended between a pair of left and right down frames.
6. The internal combustion engine as claimed in any one
of claims 1 to 5, wherein a cooling fin constituting a portion
of the cylinder is formed at a position in front of the sensor.
7. The internal combustion engine as claimed in claim

6, wherein the cooling fin is formed in an L-shape extending from a side surface to a lower surface of the cylinder.
8. The internal combustion engine as claimed in claim
1, wherein the sensor is mounted on the side of the cylinder
so as to project from the side of the cylinder substantially
horizontally in parallel to the ground.
9. The internal combustion engine as claimed in claim
1, wherein the sensor is mounted on a lower portion of the
cylinder in a manner accessible from below.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=ilA+uOV31pjq6aw4R1ZdOw==&loc=+mN2fYxnTC4l0fUd8W4CAA==

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Patent Number

268324

Indian Patent Application Number

2325/DEL/2006

PG Journal Number

35/2015

Publication Date

28-Aug-2015

Grant Date

26-Aug-2015

Date of Filing

25-Oct-2006

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMI-AOYAMA 2-CHOME, MINATO-KU, TOKYO 107-8556, JAPAN

Inventors:

#	Inventor's Name	Inventor's Address
1	RYO KUBOTA	C/O HONDA R&D CO. LTD., 4-1, CHUO 1-CHOME, WAKOSHI, SAITAMA, 351-0193, JAPAN,
2	YUJI TANAKA	C/O HONDA R&D CO. LTD., 4-1, CHUO 1-CHOME, WAKOSHI, SAITAMA, 351-0193, JAPAN
3	MASAKI FUJIWARA	C/O HONDA R&D CO. LTD., 4-1, CHUO 1-CHOME, WAKOSHI, SAITAMA, 351-0193, JAPAN

PCT International Classification Number

F02G5/02; F02B37/10

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2005-320171	2005-11-02	Japan