ES2654604T3 - Engine and saddle type vehicle that includes the same - Google Patents

Abstract

A single-cylinder or two-cylinder V-shaped engine, comprising: a cylinder head (46; 46a; 46b) that includes a head main body (65) and an protruding portion (66; 66a) protruding outward from the head main body (65), in which, when viewed on an axis of the engine cylinder (A), the protruding portion (66; 66a) extends outwardly beyond the circumference of a mounted cylinder head cover (48) in the stock (46; 46a; 46b); a combustion recess (70) formed in the main body of the head (65); an exhaust gas passage (80; 80a) of the combustion recess (70) through the protruding portion (66; 66a) to evacuate the exhaust gas from the combustion recess (70); and an oxygen concentration sensor (50; 50a) that includes a main body portion (118; 118a) and a detection portion (120) provided in the main body portion (118; 118a), to detect a concentration of oxygen in the exhaust gases; wherein the oxygen concentration sensor (50; 50a) is mounted on the protruding portion (66; 66a), with the main body portion (118; 118a) and the detection portion (120) that overlap with the protruding portion (66; 66a) as seen in a direction of the cylinder axis, at least a portion of the detection portion (120) being located inside the exhaust gas passage (80; 80a), in which neither the main body portion (118; 118a) nor the detection portion (120) leave the contour of the protruding portion (66; 66a) when viewed in the direction of the cylinder axis (A), and in that the oxygen concentration sensor (50; 50a) does not protrude beyond the main head body (65) in a left-right direction when viewed in the direction of the cylinder axis (A).

Description

DESCRIPTION

Engine and saddle type vehicle that includes the same 5 [FIELD OF THE INVENTION]

[0001] The present invention relates to an engine and a saddle type vehicle that includes the engine. More specifically, the present invention relates to an engine having an oxygen concentration sensor for the detection of an oxygen concentration in the exhaust gases; and to a chair type vehicle

10 to mount that includes the engine.

[BACKGROUND OF THE TECHNIQUE]

[0002] As a conventional technique of this category, a single cylinder engine is proposed, for example, in patent document 1.

[0003] Referring to Fig. 19 (a) and Fig. 19 (b), the single cylinder engine described in patent document 1 has a cylinder head 1a, which has a raised portion 2a on its outer circumferential surface. An exhaust gas passage 3a is formed that penetrates the raised portion 2a. With this arrangement, a sensor

Oxygen concentration 4a for the detection of an oxygen concentration in the exhaust gases is mounted on the raised portion 2a, between a mounting flange of the cylinder head cover 5a of the cylinder head 1a and the raised portion 2a of the cylinder head 1a , obliquely to an axis of the engine cylinder. Also, the oxygen concentration sensor 4a mounted on the raised portion 2a has its detection portion located inside the exhaust passage 3a. The oxygen concentration sensor 4a, like the aforementioned, is heated by high temperature exhaust gas in the exhaust gas passage 3a, and is rapidly heated to a sensor activation temperature. Therefore, it is possible to implement an oxygen concentration sensor without a heater.

[0004] Another conventional example is described in patent document 2.

[0005] Referring to Fig. 20, patent document 2 describes a single cylinder engine that

It has a space 2b for a distribution chain to drive a distribution shaft on a left side of a cylinder head 1 b as seen in the front on an axis of the cylinder. The cylinder head 1 b has a lower portion formed with an exhaust gas port inclined to the right 3b. With this arrangement, an oxygen concentration sensor 4b for the detection of an oxygen concentration in the exhaust gases is mounted on the cylinder head 1b 35 so that the detection portion of the concentration sensor 4b is located inside the port of exhaust gas 3b. In this single-cylinder engine, in addition, the oxygen concentration sensor 4b, is heated by high temperature exhaust gas passing through the exhaust gas port 3b, and is quickly heated to a sensor activation temperature. Therefore, it is possible to implement an oxygen concentration sensor without a heater.

40

[0006] It should be noted in this case that, in Fig. 19 and in Fig. 20, a crankshaft direction is defined as

a left-right direction, a direction of the cylinder axis is defined as an antero-posterior direction, and a direction perpendicular to the direction of the crankshaft and the direction of the cylinder axis is defined as an up-down direction.

Four. Five

[DOCUMENTS IN THE CONVENTIONAL TECHNIQUE]

[Patent Document]

50 [0007]

[Patent document 1] Japanese patent No. 4152796

[Patent document 2] Japanese patent open for public inspection No. 2006-183489 55 [SUMMARY OF THE INVENTION]

[Problems to be solved by the invention]

[0008] A main object of the present invention is to provide an engine in which a motor can be prevented.

outgoing element of the oxygen concentration sensor towards the outside of the cylinder head and reduce the increase in engine size, even if the oxygen concentration sensor is provided in a position where the exhaust gases have a high temperature in the cylinder head . Another object of the present invention is to provide a saddle type vehicle that includes the engine.

5

[Means to solve the problems]

[0009] According to one aspect of the present invention, a single cylinder engine or a V-twin engine is provided, which includes: a cylinder head having a head head body and an overhanging portion that

10 protrudes outward from the main head body; a combustion recess formed in the main body of the head; a passage of exhaust gases from the combustion recess through the protruding portion to evacuate the exhaust gases from the combustion recess; and an oxygen concentration sensor having a main body portion and a detection portion provided in the main body portion, to detect an oxygen concentration in the exhaust gas. With this arrangement, the oxygen concentration sensor is mounted on the protruding portion, the main body portion and the detection portion superimposed with the protruding portion as seen in a direction of the cylinder axis. In addition, at least a part of the detection portion is located inside the exhaust gas passage.

[0010] In the present invention, the cylinder head has a main body of the head and a portion protruding outwardly from the main body of the head. The exhaust gas passage is formed to penetrate the portion

that stands out. With this arrangement, the oxygen concentration sensor is mounted on the protruding portion. The main body portion and the detection portion overlap with the protruding portion when viewed in the direction of the cylinder axis. In addition, at least a part of the detection portion is located inside the exhaust gas passage. The arrangement prevents the oxygen concentration sensor from protruding outwardly beyond the cylinder head even if the oxygen concentration sensor is mounted in a position where the exhaust gas temperature is high. Therefore, the arrangement makes it possible to reduce the increase in size in the single-cylinder engine or in the V-twin engine without sacrificing its traditional feature that is compact in the left-right direction. It should be noted in this case that, although the cylinder head protrudes outwards as much as the protruding portion, the arrangement allows the exhaust apparatus that is mounted on the cylinder head to be shortened, so that an increase in size does not occur in the external structure of the engine.

[0011] Preferably, the oxygen concentration sensor as it is mounted on the protruding portion has the main body portion located in a position more advanced than the detection portion. In this case, it is possible to prevent the main body portion from interfering with the air cooling fins of the

35 cylinder body and / or a crankcase, and easily mount the oxygen concentration sensor in the cylinder head without protruding in the left-right direction.

[0012] In addition, preferably, the oxygen concentration sensor as it is mounted on the protruding portion has a central axis parallel to the axis of the cylinder. In this case, it is easy to prevent the sensor from

40 concentration of oxygen protrudes out of the cylinder head.

[0013] In addition, preferably, the protruding portion protrudes from the main body of the head at least in a downward direction. In this case, the arrangement allows efficient use of the space below the main body of the head, for the protruding portion.

Four. Five

[0014] Preferably, the protruding portion protrudes from the main body of the head in an oblique direction downward when viewed in the direction of the axis of the cylinder. In this case, the arrangement makes it possible to form the cylinder head compactly while ensuring a sufficient length of the protruding portion.

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[0015] In addition, preferably, the oxygen concentration sensor does not protrude beyond the main head body in a left-right direction when viewed in the direction of the cylinder axis. In this case, the arrangement avoids more reliably that the oxygen concentration sensor protrudes outward from the cylinder head, creating the possibility of further reducing the increase in engine size.

55

[0016] In addition, preferably, the protruding portion has an opening portion as the downstream end of the exhaust gas passage, and a center of the opening portion is not located on a side more outside than the main head body in a left-right direction when viewed in the direction of the cylinder axis. In this case, the arrangement reduces the protruding element of the portion that protrudes outwards from

the cylinder head, creating the possibility of further reducing the increase in engine size.

[0017] Preferably, the main body of the head has an outer circumferential surface with a

recess that is lowered into the head main body as seen in the direction of the cylinder axis, and the protruding portion is formed in the recess. In this case, the arrangement allows the mounting of the oxygen concentration sensor in the portion that protrudes closely with the recess, creating the possibility of reducing the protruding element of the portion that protrudes outwards from the cylinder head. Therefore, the stock is manufactured compactly.

[0018] In addition, preferably, the recess is lowered upwards. In this case, the provision makes it

It is possible to form the cylinder head compactly while ensuring a sufficient length of the protruding portion provided in the recess.

[0019] In addition, preferably, the recess is lowered laterally. In this case, the arrangement makes it possible to form the cylinder head compactly while ensuring a sufficient length of the portion that

It stands out that it is provided in the recess.

[0020] Preferably, the recess is formed as a recessed corner portion of the main body of the head. In this case, the arrangement makes it possible to form the cylinder head compactly while

20 guarantees a sufficient length of the protruding portion that is provided in the recess.

[0021] In addition, preferably, the engine further includes a cylinder head cover provided in front of the cylinder head; and a sensor cover portion provided in the cylinder head cover to cover at least a front portion of the main body portion. In this case, it is possible to cover the front and back of the

25 oxygen concentration sensor with the protruding portion and the sensor cover portion. Therefore, a saddle-type vehicle mounted with the engine can protect the oxygen concentration sensor from bouncing stones, etc. of the road surface properly. Since the oxygen concentration sensor mounted on the protruding portion overlaps the protruding portion when viewed in the direction of the cylinder axis, and is located close to the cylinder head, the sensor cover portion does not increase in size . 30

[0022] In addition, preferably, the engine further includes a cylinder head cover provided in front of the cylinder head; the cylinder head has a cover mounting surface for mounting the cylinder head cover; the protruding portion has a sensor mounting surface for mounting the oxygen concentration sensor; and the mounting surface of the cover and the mounting surface of the sensor are parallel to each other. In

In this case, the arrangement makes it easy to form the mounting surface of the cover and the mounting surface of the sensor by machining.

[0023] Preferably, the engine further includes a cylinder head cover provided in front of the cylinder head; the cylinder head has a cover mounting surface for mounting the cylinder head cover; the portion that

40 protrudes has a sensor mounting surface for mounting the oxygen concentration sensor; and the mounting surface of the cover and the mounting surface of the sensor are in the same plane. In this case, the arrangement allows simultaneous machining of the mounting surface of the cover and the mounting surface of the sensor, making it even easier to obtain the cylinder head.

[0024] In addition, preferably, the engine further includes a cylinder head cover provided in front of

the stock; and an electric cable connected to the main body portion and oriented along the head cover. In this case, the arrangement makes it possible to orient the electric cable away from the exhaust gas line formed in the cylinder head. Therefore, the damaging effect of exhaust gas heat from the passage of exhaust gas to the electric cable is reduced. The arrangement reduces the deterioration of the electric cable. Also, orienting the electric cable along the cylinder head cover provides an advantage of a reduced space necessary for the electric cable to extend into the engine.

[0025] In addition, preferably, the motor includes a clamping portion provided in the head cover to hold the electric cable. In this case, the arrangement causes the cable to be oriented easily, since the

The clamping portion makes it easy to orient the power cable along the head cover.

[0026] According to the engine offered by the present invention, it is possible to prevent the oxygen concentration sensor from protruding outward from the cylinder head, and therefore reduce the increase in engine size. Thus, the application of the engine according to the present invention corresponding to a saddle type vehicle, such

like a motorcycle, it helps reduce the increase in the size of the saddle type vehicle.

[0027] Preferably, the cylinder axis is inclined in an oblique direction forward and upward. In this case, the arrangement reduces the projecting element of the motor in a downward direction. Therefore a

Such a configuration can be suitably used for a saddle-type vehicle that includes a single-cylinder or V-twin engine.

[0028] In the present invention, the expression "outwardly", used with respect to the cylinder head, refers to all radial directions that are perpendicular to the axis of the cylinder, including not only the lateral directions.

10 outward (left-right), but also external directions up / down.

[0029] In addition, the expression that the "main body portion and the detection portion overlap with the protruding part as seen in a direction of the cylinder axis" means that neither the main body portion nor the portion of detection leave the contour of the protruding portion when viewed in one direction

15 of the cylinder shaft.

[0030] The object described above and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention with reference to the accompanying drawings.

twenty

[Advantages of the invention]

[0031] According to the present invention, an outgoing element of the oxygen concentration sensor towards the outside of the cylinder head can be prevented and the increase in engine size can be reduced even if the sensor

The oxygen concentration is arranged in a position in which the exhaust gas has a high temperature in the cylinder head.

[0032] Thus, problems associated with conventional techniques can be avoided. To be more specific, the oxygen concentration sensor 4a in patent document 1 does not interfere with a portion

30 of bulge 6a which is used to connect the cylinder head 1a with the cylinder body, nor with a cylinder head cover that is arranged in front of the cylinder head 1a. However, as shown in Fig. 19 (b), although the oxygen concentration sensor 4a does not interfere with the flange 5a, the oxygen concentration sensor 4a has its end portion protruding to the left of the cylinder head. 1st.

[0033] In patent document 2, the oxygen concentration sensor 4b extends to the right

of a portion of the right side of the exhaust gas port 3b, and does not interfere with a portion of the left side of the cylinder head 1b or the cylinder head cover. However, when the cylinder head 1b is seen in the direction of the cylinder axis, the oxygen concentration sensor 4b has its end portion (a right end portion in Fig. 20) that protrudes largely to the right of cylinder head 1b.

40

[0034] As described, in any of the engines offered in patent documents 1 and 2, the oxygen concentration sensor protrudes to the left or right of the cylinder head, adding extra dimensions to the engine. This is especially unfavorable in single-cylinder and V-twin-cylinder engines because their traditional advantage is lost that they can be compact in a left direction.

45 right.

[BRIEF DESCRIPTION OF THE DRAWINGS]

[0035]

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Fig. 1 is a left side view of a motorcycle according to an embodiment of the present invention.

Fig. 2 is a left side view of a power unit, a rear wheel and its adjacent region.

Fig. 3 is a drawing when a motorcycle frame, power unit, rear wheel and its adjacent region are seen in the front, on an axis of the cylinder.

Fig. 4 is a drawing when an engine according to an embodiment of the present invention is seen on the front, on an axis of the cylinder.

Fig. 5 is a right side view of a main portion of the engine.

Fig. 6 is a perspective view of a main portion of the engine.

Fig. 7 is a drawing of a partial section taken on lines I-I in Fig. 4.

Fig. 8 is a sectional view taken on lines II-II of Fig. 5.

Fig. 9 is a drawing when an engine according to another embodiment of the present invention is seen in the front, on an axis of the cylinder.

Fig. 10 is a right side view partially not illustrated, showing an example of an engine mounted with an air jacket.

Fig. 11 (a) is a drawing of a main portion and an adjacent region of an example of a cylinder head cover, formed with a sensor cover portion as seen in the front, on a cylinder axis; and Fig. 11 (b) is a perspective view thereof.

Fig. 12 (a) is a drawing of a main portion and an adjacent region of another example of cylinder head cover 10 formed with a sensor cover portion as seen in the front, on a cylinder axis; and Fig. 12 (b) is a perspective view thereof.

Fig. 13 is a drawing with a partial section, showing a motor according to another embodiment of the present invention.

Fig. 14 is a drawing when an engine according to another embodiment of the present invention is seen at the front, 15 on an axis of the cylinder.

Fig. 15 is a drawing of a main portion, showing an oxygen concentration sensor mounted on a portion that projects at an inclination.

Fig. 16 is a drawing of a section taken on lines III-III of Fig. 15.

Fig. 17 (a) is a drawing when a V-twin engine according to an embodiment of the present invention is seen on one side; and Fig. 17 (b) is a drawing when the engine is viewed from above.

Fig. 18 is a left side view of a motorcycle according to another embodiment of the present invention.

Fig. 19 (a) and Fig. 19 (b) are perspective views of a stock according to patent document 1.

Fig. 20 is a sectional view of a cylinder head according to patent document 2.

25 [MODES OF CARRYING OUT THE INVENTION]

[0036] Hereinafter, the embodiments of the present invention will be described with reference to the drawings.

[0037] It should be noted in this case, that when the engines according to the present invention are described, a crankshaft direction is defined as a left-right direction, a cylinder axis direction is defined

as an antero-posterior direction, and a direction perpendicular to the direction of the crankshaft and the direction of the cylinder axis is defined as an up-down direction. When describing motorcycles according to the embodiments of the present invention, a left-right direction, an antero-rear direction, and an up-down direction are defined from the position of the motorcyclist on the motorcycle in a motorcycle seat. , the motorcyclist being oriented towards a handlebar. In the figures, a cross-shaped arrow mark indicates directions: an arrow "F" indicates forward, "Rr" indicates backward, "U" indicates upward, "Lo" indicates downward, "R" indicates a on the right, and "L" indicates on the left.

[0038] Fig. 1 is a left side view of a so-called scooter type motorcycle 10 that includes a motor 36 according to an embodiment of the present invention.

[0039] Referring to Fig. 1, the motorcycle 10 includes a motorcycle frame 12. In a front portion of the motorcycle frame 12, a handlebar 14 is disposed in an upper position, and there is a front wheel 16 arranged in a lower position. In a rear position above the frame of the

45 motorcycle 12, a seat 18 for the motorcycle rider is arranged. Between the handlebar 14 and the seat, along the frame of the motorcycle 12, a footrest 20 is arranged for the motorcyclist to rest his feet. The footrest 20 has a portion for the right foot and a portion for the left foot for the biker in the seat 18, and these two portions are continuous at the same level. This arrangement provides a large available space above the footrest 20, between the handlebar 14 and the seat 18. The motorcycle frame 12 is arranged so that it passes under the footrest 20.

[0040] The motorcycle frame 12 includes a pair of frames 22 arranged in a left-right direction in a space between them, (see Fig. 3). The frames 22 are separated by a predetermined distance in the left-right direction, which extends in an oblique direction back and forth.

55 above. The pair of frames 22 supports a power unit 26 pivotally in an up-down direction through a connection mechanism 24.

[0041] The connection mechanism 24 has an oscillating shaft 28 that connects the pair of frames 22, and a connection member 30 that connects the oscillating shaft 28 and the power unit 26 to each other and is pivotable in the

up-down direction around the oscillating axis 28.

[0042] Power unit 26 is located under the seat. The power unit 26 has its rear portion connected to the frames 22 by a rear damping unit 32. The power unit 26 has

5 a rear end portion provided with a rear wheel 34.

[0043] Fig. 2 is a left side view of the power unit 26, the rear wheel 34 and its adjacent region. Fig. 3 is a drawing when the motorcycle frame 12, the power unit 26, the rear wheel 34 and its adjacent region are seen at the front, on an axis of the cylinder A.

10

[0044] The power unit 26 includes a motor 36 that is of a single-cylinder type air-cooled, for example; and a transmission case 38 incorporating the power transmission equipment (not shown) that includes a transmission, a speed reducer, etc.

15 [0045] In a side view of the motorcycle 10, the engine 36 36 crosses the frame 22. The engine 36 has a

crankshaft 40, a crankcase 42, a cylinder body 44, a cylinder head 46 and a cylinder head cover 48. The crankcase 42, the cylinder body 44, the cylinder head 46 and the cylinder head cover 48 are on a cylinder axis A of the engine 36, in this order from back to front, in the front-rear direction of the motorcycle. The crankcase 42, the cylinder body 44, the cylinder head 46 and the cylinder head cover 48 are connected with their adjacent members. As shown in Fig. 1 and in Fig. 2, the axis of the cylinder A is inclined in an oblique direction forward and upward with respect to the front-rear direction of the motorcycle. In this embodiment, the A axis is tilted slightly.

[0046] The crankcase 42 rotatably supports the crankshaft 40 which extends in the left-right direction. As shown in Fig. 3, the crankcase 42 has its right portion located behind the frames 22. Also, the

25 cylinder body 44, the cylinder head 46 and the cylinder head cover 48 are located between the left and right pair of frames 22 when viewed in the direction of the axis of the cylinder A so that the power unit 26 is pivotable in the direction from top to bottom without interfering with the racks 22.

[0047] The transmission box 38 is behind the frames 22, to the left of the crankcase 42. The transmission box 38 has a rear end portion, in which a rear wheel 34 is mounted so

swivel The rear wheel 34 is behind the engine 36, arranged side by side of the transmission case 38 in the direction of the width of the motorcycle. The power of the engine 36 is transmitted to the rear wheel 34 through the power transmission equipment.

[0048] As will be described later, the cylinder head 46 is provided with an oxygen concentration sensor 50

for the detection of an oxygen concentration in the exhaust gas evacuated from a combustion chamber 90 (a combustion recess 70 in the cylinder head 46) of the engine 36; and an oil temperature sensor 52 for detecting a temperature of the engine oil flowing in the engine 36. In addition, the cylinder head 46 has an upper surface connected with an air intake apparatus 54 for supplying air to the combustion chamber 90 through an air intake passage 74 of the engine 36. The cylinder head 46 has a lower portion connected with an exhaust apparatus 56 to evacuate the exhaust gas from the combustion chamber 90 of the engine 36 through an air passage exhaust gas 80.

[0049] Referring from Fig. 4 to Fig. 8, the engine 36 will be detailed.

Four. Five

[0050] Fig. 4 is a drawing of the engine 36 as seen in the front, on the axis of the cylinder A. Fig. 5 is a right side view of a main portion of the engine 36. Fig. 6 is a perspective view of a main portion of the engine 36. Fig. 7 is a drawing of a partial section taken on lines II in Fig. 4. Fig. 8 is a sectional view taken on lines II-II of Fig. 5.

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[0051] The cylinder body 44 has air cooling fins 58 on its outer side surfaces, and has a cylindrical cylinder bore 60 that extends in the direction of the axis of the cylinder A inside. Inside the bore of the cylinder 60, a piston 62 is oscillating. The piston 62 is connected to the crankshaft 40 by a connecting rod 64. It should be noted in this invention that the axis of the cylinder A is a longitudinal center axis of the bore

55 cylinder 60.

[0052] The cylinder head 46 has a main body of the head 65 and an overhang portion 66. The protruding portion 66 is on an outer circumferential surface of the main body of the head 65, which projects outwardly from the head of the main body 65 With reference to Fig. 4 and Fig. 6, the surface

The outer circumferential of the main body of the head 65 has a curved recess 68 that is lowered into the main body of the head 65 as seen in the direction of the axis of the cylinder A. Specifically, the recess 68 is lowered upwards, to a level higher than a lower surface 65a of the main body of the head 65. In addition, the recess 68 is lowered laterally (to a position more to the left than a surface to the right 65b of the 5 main body of the head 65, in the present embodiment ). In addition, the recess 68 is formed as a portion of the recessed corner of the main body of the head 65. In other words, the recess 68 extends in the direction of the axis of the cylinder A on the outer circumferential surface of the main body of the head 65.

[0053] The protruding portion 66 is disposed in recess 68 when viewed at the front in the

10 direction of the axis of the cylinder A. When viewed at the front in the direction of the axis of the cylinder A, the protruding portion 66 protrudes from the main body of the head 65 in an oblique direction to the right and down. It should be noted in this case that the oxygen concentration sensor 50 does not protrude in the left-right direction beyond the main head body 65 when viewed in the direction of the axis of the cylinder A.

[0054] As shown in Fig. 7, the main body of the head 65, which is included in the stock 46, has

a rear end portion formed with the combustion recess 70. The combustion recess 70 and the opening portion 72 on the upper surface of the cylinder head 46 communicate with each other through the air intake passage 74. An opening of the passage air intake 74 on a surface of the combustion recess 70 represents an air intake port 76. The air intake apparatus 54 is connected to the opening portion 72. The combustion recess 70 communicates with a portion of opening 78 of the protruding portion 66 through the exhaust gas passage 80. An opening of the exhaust gas passage 80 on a surface of the combustion recess 70 represents an exhaust gas port 82. The opening portion 78 in the protruding portion 66 is connected to the exhaust apparatus 56. The exhaust apparatus 56 has a flange portion 84 at its end portion, and the flange portion 84 is mounted on the protruding portion 66 with pe threaded rims 86 and nuts 88.

25

[0055] Referring to Fig. 4, when the engine 36 is seen at the front, in the direction of the axis of the cylinder A, the exhaust gas passage 80 in the cylinder head 46 extends at a downward inclination with with respect to the up-down direction (a direction perpendicular to both the crankshaft 40 and the axis of the cylinder A). More specifically, when the engine 36 is seen in the front, in the direction of the axis of the cylinder A, the gas passage

Exhaust 30 80, which is formed in the cylinder head 46, extends in an oblique direction to the right and down of the combustion chamber 90 (the combustion recess 70) and the exhaust gas port 82. In addition, the opening portion 78 of the protruding portion 66, which represents the downstream end of the exhaust gas passage 80, is inclined with respect to the up-down direction. More specifically, the opening portion 78 of the protruding portion 66, which represents the downstream end of the exhaust gas passage 80, is oriented in a direction to the right and downward obliquely. In addition, the opening portion 78 has a center 79, it is not located on one side more to the outside than the main body of the head 65 in the left-right direction when viewed in the direction of the axis of the cylinder A. As described , the exhaust gas passage 80 is also formed in the protruding portion 66. The exhaust gas passage 80 extends away from a transmission member 98 and a rotation member 100 (which will be described later) which are arranged on the left side 40 of the engine 36. It should be noted in this case that the combustion chamber 90 is a space provided by the bore of the cylinder 60, the piston 62 and the combustion recess 70.

[0056] In the engine 36, the air passes through the air intake apparatus 54 and the air intake passage 74, and reaches the combustion chamber 90. The exhaust gas of the combustion chamber 90 passes through the passage of gas

45 exhaust 80 and the exhaust apparatus 56 and then goes outside.

[0057] Referring to Fig. 7, the engine 36 further includes a valve actuator 92, an air intake valve 94 and an exhaust valve 96.

[0058] The valve actuator 92 includes the transmission member 98, the member of

rotation 100, a distribution shaft 102, a cam 104 and arm members 106, 108. The transmission member 98 includes a metal chain, for example, and is connected to the crankshaft 40 and the rotation member 100 to each other to transmit the rotation of the crankshaft 40 to the rotation member 100. The rotation member 100 is provided by a chain sprocket for example, and rotates by the transmission member 98. The rotation member 100 rotates the distribution shaft 102. The shaft Distribution 102 is provided with cam 104, which pivots arm members 106, 108. Arm member 106 drives air intake valve 94, which opens and closes air intake port 76 while member of arm 108 operates the exhaust valve 96, which opens and closes the exhaust gas port 82.

[0059] The cylinder head 46 has a mounting surface of the cover 110, on which the cover of the

cylinder head 48. As shown in Fig. 4 through Fig. 6, a plurality (two in the present embodiment) of fasteners 111, such as bolts, is inserted from a front surface of the cylinder head cover 48 to secure the cylinder head cover 48 to the cylinder head 46. With the mounting of the cylinder head cover 48 to the mounting surface of the cover 110 as described above, the arrangement eliminates the need for a flange that is necessary to mount the cylinder head. cylinder head cover on the cylinder head 46. Therefore, the oxygen concentration sensor 50 can be

extend in the direction of the axis of the cylinder A. The fasteners 111 can be provided by

ordinary fasteners such as threaded bolts and nuts, rivets, etc.

[0060] The protruding portion 66 has a mounting surface of the sensor 112, and the sensor of

Oxygen concentration 50 is mounted on the mounting surface of the sensor 112.

[0061] The mounting surface of the cover 110 and the mounting surface of the sensor 112 are parallel to each other.

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[0062] Now, attention should be paid in this case to an arrangement whose concentration sensor of

oxygen 50, which serves to detect an oxygen concentration in the exhaust gas passing through the exhaust gas passage 80 and is mounted on the mounting surface of the sensor 112 of the protruding portion 66, overlaps

with the protruding portion 66 of the cylinder head 46 when viewed in the direction of the axis of the cylinder A. The expression

20 "oxygen concentration sensor 50 that overlaps the protruding portion 66 when viewed in the direction of the axis of the cylinder A" means that the oxygen concentration sensor 50 does not exit the contour of the protruding portion 66 when it is seen in the direction of the axis of the cylinder A. As will be described later, a central axis B of the oxygen concentration sensor 50 may be parallel to the axis of the cylinder A, or it may be inclined to the axis of the cylinder A.

25

[0063] The mounting surface of the sensor 112 is formed with a mounting hole 114, which communicates with the exhaust passage 80 and is parallel to the axis of the cylinder A. The mounting hole 114 has a female threaded portion 116 .

[0064] The oxygen concentration sensor 50 includes a columnar main body portion 118 and a

round columnar detection portion 120 coaxially provided with the main body portion 114 at one end of the main body portion 114. The oxygen concentration sensor 50 is columnar, and its axial length is greater than its radius. The main body portion 118 has a male threaded portion 122. In the present embodiment, the main body portion 118 has different diameters depending on their positions.

35 axial

[0065] When the oxygen concentration sensor 50 is mounted on the protruding portion 66 by screwing the male threaded portion 122 into the female threaded portion 116, the detection portion 120 is inserted into the mounting hole 114 and exposed in the exhaust gas passage 80. As the concentration sensor

Oxygen 40 is mounted on the protruding portion 66, the main body portion 118 and the detection portion 120 overlap with the protruding portion 66 of the cylinder head 46 when viewed in the direction of the axis of the cylinder A. Also , as mounted on the protruding portion 66, the oxygen concentration sensor 50 is disposed along the recess 68. In other words, the columnar oxygen concentration sensor 50 is arranged in the direction in which the recess 68 extends. Once the oxygen concentration sensor 50

45 is mounted, the central axis B of the oxygen concentration sensor 50 and the axis of the cylinder A are parallel to each other, and at least a part of the detection portion 120 is located inside the exhaust gas passage 80.

[0066] The main body portion 118 has another end portion connected to a connector 125 of an electrical cable 124. In the present embodiment, the electrical cable 124 is removable and fixed to the body portion.

Main 50 118. The detection portion 120 of the oxygen concentration sensor 50 contains stabilized zirconium for example, and is ready for precise detection at a temperature not lower than the activation temperature of the predetermined sensor. Since at least a portion of the detection portion 120 is located within the exhaust gas passage 80 where the exhaust gas passes at a high temperature, the detection portion 120 is heated by the exhaust gas. In this way, the oxygen concentration sensor 50 quickly reaches its temperature of

55 sensor activation. Therefore, the oxygen concentration sensor 50 is provided by a sensor without a heater that does not need any heating means to heat the detection portion 120, so that the oxygen concentration sensor 50 is small and inexpensive.

[0067] The detection signals from the oxygen concentration sensor 50 are sent to the motor controller 126 via the electrical cable 124. Based on the detection of the received signals, the

Engine controller 126 controls the air-fuel ratio of the fuel supplied to the combustion chamber 90 at an optimum level. Specifically, the engine controller 126 operates a fuel injection valve 128 disposed in the air intake apparatus 54, whereby fuel is injected into the air supplied to the combustion chamber 90.

5

[0068] Also, as shown in Fig. 4, Fig. 6 and Fig. 8, the stock 46 has a protruding portion 130

for mounting the oil temperature sensor on a lateral surface of the cylinder head 46. The protruding portion 130 is formed in an upper region on a right lateral surface of the cylinder head 46. The protruding portion 130 has a protruding hole 132, which is communicates with an oil passage 134 formed inside the cylinder head 46. The oil passage 134 is parallel to the axis of the cylinder A. Also, within the cylinder head 46, a bearing 136 is formed by the distribution shaft 102. The bearing 136 and the outgoing hole 132 communicate with each other through the oil passage 138. The oil temperature sensor 52 is mounted on the outgoing portion 130 which has an arrangement as described.

[0069] As the crankshaft 40 is supported by the rotating crankcase 42, an oil pump is driven to

through an intermediate wheel inside the crankcase 42. It supplies oil from the oil pump, through an oil passage formed in the crankcase 42, an oil passage formed on a contact surface between the crankcase 42 and the body of the cylinder 44, an oil passage formed in the cylinder body 44 and the oil passage 134 formed in the cylinder head 46, and the distribution shaft 102 and the valve actuator 92. The oil of the oil pump 20 is It also supplies the crankshaft 40 and an oil cooler. As described, the oil is constantly and strongly supplied from the oil pump to the lines connected directly to it, as long as the crankshaft 40 is rotating.

[0070] The oil temperature sensor 52 is placed near the combustion chamber 90, where there is a

25 constant flow of oil while crankshaft 40 is rotating. Therefore, it is possible to detect a temperature of the combustion chamber 90, that is, a temperature of the engine 36, precisely with the oil temperature sensor 52, while the crankshaft 40 is rotating. The values detected by the oil temperature sensor 52 are used in setting and correcting the fuel injection amount.

[0071] According to the motorcycle 10 which includes the engine 36 described, the cylinder head 46 has its portion which

protrudes 66 on an oblique surface to the right and down an outer circumferential surface of the main body of the head 65, and the passage of exhaust gases 80 extends from the combustion chamber 90 in an oblique direction to the right and down to penetrate the protruding portion 66. The opening portion 78 at the downstream end of the protruding portion 66 is oriented in an oblique direction to the right and down. With this arrangement, the main body portion 118 and the detection portion 120 of the oxygen concentration sensor 50 overlap with the protruding portion 66 when viewed in the direction of the axis of the cylinder A, and at least a portion of the Detection portion 120 is located within the exhaust passage 80, once the oxygen concentration sensor 50 is mounted on the protruding portion 66.

[0072] These arrangements prevent the oxygen concentration sensor 50 from protruding to a position

farther outward (especially in the left-right direction) than the cylinder head 46, even if the oxygen concentration sensor 50 is mounted on the protruding portion 66 of the cylinder head 46 where the exhaust gas temperature is high. Therefore, the single cylinder engine 36 does not lose its compactness characteristic in the left-right direction. The arrangements make it possible to reduce the increase in size in the single cylinder engine 45. The oxygen concentration sensor 50 does not protrude beyond the cylinder head cover 48 in the forward direction. The arrangements, therefore, also prevent the oxygen concentration sensor 50 from protruding in the front-rear directions of the engine 36. In addition, in the engine 36, the valve actuating device 92 has its front end portion located more ahead of the exhaust gas passage 80. As a result, there is a sufficiently long distance from the sensor mounting surface 112 50 of the protruding portion 66 to the front surface of the cylinder head cover 48 in the direction of the cylinder axis A. More specifically, the distance from the sensor mounting surface 112 of the protruding portion 66 to the front surface of the cylinder head cover 48 in the direction of the axis of the cylinder A is longer than a portion of the concentration sensor of oxygen 50 exposed from the mounting surface of the sensor 112. Therefore, the electrical cable 124 connected to the oxygen concentration sensor 50 does not overhang In front of the motor 36. The arrangement can reduce the space necessary to orient the electric cable 124. It should be noted in this case that, although the cylinder head 46 protrudes outwards as much as the protruding portion 66, the arrangement allows the apparatus Exhaust 56 that is mounted on the cylinder head 46 is shortened a maximum, so there is no increase in size in the outer structure of the engine.

[0073] Especially, in the engine 36 according to the present embodiment, the distance from the sensor mounting surface 112 of the protruding portion 66 to the front surface of the cylinder head cover 48 in the direction of the axis of the cylinder A is long enough, and the oxygen concentration sensor 50 is columnar, its axial length being greater than its radius. In such an arrangement, it is easy to arrange the concentration sensor of

Oxygen 50 in the cylinder head 46 so that it overlaps the protruding portion 66 when viewed in the direction of the axis of the cylinder A, and the present invention is particularly advantageous.

[0074] Once the oxygen concentration sensor 50 is mounted on the protruding portion 66, the main body portion 118 is positioned further forward than the detection portion 120. By

10 therefore, it is possible to prevent the main body portion 118 from interfering with the air cooling fins 58 of the cylinder body 44 and / or the crankcase 42, creating the possibility of mounting the oxygen concentration sensor 50 with ease in cylinder head 46 without protruding in the left-right direction.

[0075] As it is mounted on the cylinder head 46, the central axis B of the oxygen concentration sensor 50 is parallel to the axis of the cylinder A. The arrangement makes it easy to prevent the oxygen concentration sensor 50

it stands out in the left-right direction and in the downward direction.

[0076] The protruding portion 66 protrudes from the main body of the head 65 at least in a downward direction. The arrangement allows efficient use of the space under the main body of the head 65, for the portion

20 protruding 66.

[0077] The protruding portion 66 protrudes in an oblique downward direction of the main body of the head 65 when viewed in the direction of the axis of the cylinder A. The arrangement creates the possibility of forming the cylinder head 46 in a compact manner while ensuring a sufficient length of the protruding portion 66.

25

[0078] The oxygen concentration sensor 50 does not protrude in the left-right direction beyond the main body of the head 65 when viewed in the direction of the axis of the cylinder A. The arrangement avoids more reliably than the concentration sensor of oxygen 50, protrudes outwardly from the cylinder head 46, so it is possible to further reduce the increase in size in the engine 36.

30

[0079] The protruding portion 66 has the opening portion 78, which represents the downstream end of the exhaust gas passage 80, and the opening portion 78 has its center 79, which is not located on an outermost side. that the main body of the head 65 in the left-right direction when viewed in the direction of the axis of the cylinder A. The arrangement reduces the protrusion of the protruding portion 66 towards the outside of the cylinder head.

35 46, creating the possibility of further reducing the dimensional increase in the engine 36.

[0080] The outer circumferential surface of the main body of the head 65 has the recess 68 that is lowered into the main body of the head 65 as seen in the direction of the axis of the cylinder A, and the protruding portion 66 is formed in the recess 68. Such an arrangement as the one above allows the assembly

40 of the oxygen concentration sensor 50 in the protruding portion 66 near the recess 68, creating the possibility of reducing the protruding element of the protruding portion 66 outwardly of the cylinder head 46. Therefore, the cylinder head 46 can be do compactly.

[0081] The recess 68 is lowered upwards and laterally. In addition, the recess 68 is formed as a portion of the recessed corner of the main body of the head 65. The arrangement makes it possible to form the cylinder head

46 in a compact manner while ensuring a sufficient length for the protruding portion 66 that is formed in the recess 68.

[0082] The mounting surface of the cover 110 and the mounting surface of the sensor 112 are parallel to each other. The arrangement makes it easy to form the mounting surface of the cover 110 and the surface of

112 sensor assembly by machining.

[0083] The axis of the cylinder A is inclined in an oblique direction forward and upward. This makes it possible to reduce the protruding element downward of the motor 36. Therefore, such a configuration can

55 suitably used for a saddle-type vehicle that includes a single-cylinder or V-twin engine.

[0084] It should be noted in this case that, although the embodiment described above uses a connection mechanism 24, the power unit 26 may be mounted directly on the motorcycle frame 12, of

pivoting way in the up-down direction without using the connection mechanism 24.

[0085] The transmission member 98 may be provided by a rubber strap for example. In this case, the rotation member 90 will be provided by a pulley.

5

[0086] Fig. 9 is a drawing when an engine 36a according to another embodiment of the present invention is seen in the front, on an axis of the cylinder A.

[0087] In the engine 36a, the oxygen concentration sensor 50 is replaced with an oxygen concentration sensor 50a having an electric cable 124a; the electric cable 124 is replaced with a cable

electric 124b; and the clamping portions 140 are formed in the cylinder head cover 48. Other configurations are identical to the engine 36 of Fig. 4 to Fig. 7, so that in this case a repetitive description will not be given.

[0088] The oxygen concentration sensor 50a has a main body portion 118a. One end 15 of the electrical cable 124a is connected to an interior of the main body portion 118a, and the electrical cable 124a

it extends in the main body portion 118a. The other end of the electrical cable 124a is connected to the motor controller 126 through the electrical cable 124b. It should be noted in this case that electrical wires 124a and 124b have connectors 125a and 125b, respectively. The connection of connectors 125a and 125b to each other establishes a connection between electrical wires 124a and 124b.

twenty

[0089] The cylinder head cover 48 has its front surface provided with a plurality (four in the present embodiment) of clamping portions 140. These clamping portions 140 hold the electric cable 124a which is connected to the main body portion 118 of the 50a oxygen concentration sensor. The clamping portions 140 can be formed integrally with the cylinder head cover 48 or separately as parts

25 singles In addition, the clamping portions 140 may be provided by an adhesive or an adhesive tape that presses the electrical cable 124a on the cylinder head cover 48. In addition, the clamping portions 140 may be provided by generally C-shaped or shaped structures. of U through which the electrical cable 124a is inserted and maintained in that way. Also, as indicated by alternate long and short dashed lines in Fig. 9, the clamping portions 140 may be formed on the right side surface of the cylinder head cover 48. In addition, the clamping portions 140 may be formed on any of the left side surface, an upper surface and a lower surface of the cylinder head cover 48.

[0090] The clamping portions 140 that hold the electric cable 124a along the head cover 48, as described, make it possible to guide the electric cable 124a away from the passage of exhaust gas 80 that forms

35 in the cylinder head 46. Therefore, the detrimental effect of the exhaust gas heat from the exhaust gas passage 80 to the electric cable 124a is now reduced. The arrangement reduces the deterioration of the electric cable 124a. By guiding the electric cable 124a along the cylinder head cover 48 there is also a space reduction advantage for the electric cable 124a outside the engine 36a. In addition, the use of the clamping portions 140 makes guiding the electric cable 124a easy.

40

[0091] It should be noted in this case that the clamping portions 140 can be used in the previous embodiment. In this case, the clamping portions 140 maintain the electrical cable 124 that is connected to the oxygen concentration sensor 50.

[0092] Fig. 10 is a right side view partially not illustrated, showing the engine 36 mounted

with an air jacket 142.

[0093] As exemplified in Fig. 10, the motor 36 shown in Fig. 4 through Fig. 7 may be provided with an air jacket 142; the air jacket 142 may have its surface formed with clamping portions 140; and the

50 electric cable 124 connected to the oxygen concentration sensor 50 may be held by the clamping portions 140. In addition, the clamping portions 140 may be provided in the cylinder head 46.

[0094] Fig. 11 (a) is a drawing of a main portion and an adjacent region of the cylinder head cover 48 formed with a sensor cover portion 144 as seen in the front part on the axis of the cylinder A. Fig.

55 11 (b) is a perspective view of it.

[0095] As shown in Fig. 11 (a) and Fig. 11 (b), the sensor cover portion 144 may be formed integrally with the cylinder head cover 48, in a corner portion of the cylinder head cover 48 near the oxygen concentration sensor 50.

[0096] The cover portion of the sensor 144 has a front cover portion 146 that covers a front portion of the main body portion 118 of the oxygen concentration sensor 50; and a lateral cover portion 148 partially covering an external surface of the main body portion 118. Note

5 that the expression "outward" of the main body portion 118 refers to all radial directions that are perpendicular to the central axis B of the oxygen concentration sensor 50 and that extend radially outward from the central axis B .

[0097] A motorcycle 10 mounted with an engine 36 having a cylinder head cover 48 formed with the sensor cover portion 144 can properly protect the oxygen concentration sensor 50, from

bouncing stones, etc. coming from the road surface. The oxygen concentration sensor 50 mounted on the cylinder head 66 overlaps the protruding portion 66 as seen in the direction of the axis of the cylinder A, and is in proximity to the cylinder head 46. Therefore, the cover portion of the Sensor 144 does not increase in size.

[0098] Fig. 12 (a) is a drawing of a primary portion and an adjacent region of the cylinder head cover 48

formed with a cover portion of the sensor 144a as seen in the front part on the axis of the cylinder A. Fig. 12 (b) is a perspective view thereof.

[0099] As shown in Fig. 12 (a) and Fig. 12 (b), the covered portion of the sensor 144a, which is a separate part, can be mounted with fasteners 150, such as bolts, to a corner portion of the

cylinder head cover 48 near the oxygen concentration sensor 50. The sensor cover portion 144a has a front cover portion 146a that covers a front portion of the main body portion 118 of the oxygen concentration sensor 50; and a lateral cover portion 148a partially covering an external surface of the main body portion 118.

25

[0100] Again, in this case, the arrangement provides the same advantages as the case in which the engine 36 has the cylinder head cover 48 formed with the sensor cover portion 144.

[0101] It should be noted in this case that the fasteners 150 are not limited to screws, but any fastener that is capable of providing proper fastening can be 30. Cylinder head cover 48

it may be provided with a rotation stop (not illustrated), formed as a projecting element for example, in order to prevent the rotation of the cover portion of the sensor 144a that is mounted on the head cover 48.

[0102] In cases where the oxygen concentration sensor is provided by the oxygen concentration sensor 50a in Fig. 9, the sensor covers 144, 144a may be formed in the cover

of cylinder head 48.

[0103] In addition, the cover portions of the sensor 144, 144a may have only the front cover portions 146, 146a respectively, to cover at least a front portion of the main body portion 118

40 of the oxygen concentration sensor 50.

[0104] Fig. 13 is a drawing, with a partial section, of a motor 36b according to another embodiment of the present invention.

[0105] Referring to Fig. 13, the engine 36b includes a cylinder head 46a, where a surface of

cover assembly 110 for mounting the cylinder head cover 48 and a sensor mounting surface 112a for mounting the oxygen concentration sensor 50 are in the same plane. Specifically, the mounting surface of the cover 110 and the mounting surface of the sensor 112a are level with each other. Other configurations are identical to the motor 36 in Fig. 7, so that in this case a repetitive description will not be given.

fifty

[0106] In this case, the arrangement allows simultaneous machining of the mounting surface of the cover 110 and the mounting surface of the sensor 112a, which makes it even easier to obtain the stock 46a.

[0107] Fig. 14 is a drawing when an engine 36c according to another embodiment of the present invention is seen in front, on an axis of the cylinder A.

[0108] In the engine 36c shown in Fig. 14, the cylinder head 46 having the protruding portion 66 is replaced with a cylinder head 46b having an protruding portion 66a.

[0109] When the engine 36c is seen at the front in the axis of the cylinder A, the protruding portion 66a protrudes downward from the cylinder head 46b, and the downstream end of the exhaust gas passage 80a represented by a portion of opening 78a is oriented in an oblique direction to the left and down. In addition, the cylinder head 46b is formed with an exhaust gas passage 80a, which extends downwards from a chamber of

5 combustion 90 and an exhaust gas port 82. Other configurations are identical to the engine 36 in Fig. 4, so that in this case a repetitive description will not be given.

[0110] Engine 36c provides the same advantages as engine 36.

[0111] Fig. 15 is a drawing of a main portion, showing an oxygen concentration sensor

50 mounted on a portion that projects 66 on an inclination. Fig. 16 is a drawing of a section taken on the MI-MI lines of Fig. 15.

[0112] As shown in Fig. 15 and Fig. 16, the oxygen concentration sensor 50 may be inclined so that its central axis B is offset with respect to the axis of the cylinder A. For a comparative purpose, the

Alternate long and short dashed lines show the oxygen concentration sensor 50 which is arranged so that its central axis B is parallel to the axis of the cylinder A.

[0113] The angle of the central axis B with respect to the axis of the cylinder A is discretionary, provided that the main body portion 118 and the detection portion 120 of the oxygen concentration sensor 50 overlaps with the

protruding portion 66 of the cylinder head 46 when viewed in the direction of the axis of the cylinder A. In other words, with reference to Fig. 16, the oxygen concentration sensor 50 may be inclined on the axis of the cylinder A, inside of an interval in which the main body portion 118 and the detection portion 120 are not outside a range defined by a line C and a line D. Line C contacts an end of the portion that protrudes 66 , and is parallel to the axis of the cylinder A while the line D is brought into contact with the other end of the protruding portion 66, and is parallel to the axis of the cylinder A.

[0114] It should be noted in this case that the requirement is only that the main body part 118 be between the line C and the line D when viewed in the direction of the axis of the cylinder A. The electric cable 124 (124a)

30 connected to the main body portion 118 does not have to be between line C and line D.

[0115] Fig. 17 (a) is a drawing when a twin-cylinder engine in V 36d according to another embodiment of the present

invention is seen laterally. Fig. 17 (b) is a drawing when the engine 36d is viewed from above.

35 [0116] In the engine 36d, each of the two cylinder heads 46 is provided with the oxygen concentration sensor

50. The oxygen concentration sensor 50 may be mounted on only one of the cylinder heads 46 in the two cylinders, to control the engine 36d.

[0117] As described, the present invention is applicable not only to single-cylinder engines, but also to V-twin-cylinder engines in which a plurality of cylinders do not align in the left direction.

right.

[0118] Fig. 18 is a left side view of a motorcycle 10a according to another embodiment of the present invention.

Four. Five

[0119] The motorcycle 10a is a so-called underbone motorcycle in which an engine 36e is arranged under a motorcycle frame 152.

[0120] Referring to Fig. 18, the motorcycle 10a includes a motorcycle frame 152. The motorcycle frame 152 includes a collecting tube 154, a main frame 156 and a seat frame 158. The

manifold tube 154 is located in a front end portion of the motorcycle frame 152, in a lateral center thereof. The main frame 156 extends from the collecting tube 154 in an oblique direction back and down in a lateral central plane. The seat frame 158 extends from the main frame 156 in an oblique direction back and up.

55

[0121] The collecting tube 154 supports a front shroud 160 orientable in the left-right direction, and the front shroud 160 rotatably supports a front wheel 162 in its lower end portion. The front cover 160 has its upper end portion provided with a steering handlebar 164.

[0122] The engine 36e is an air-cooled single-cylinder engine, supported by the main frame 156 from above, with its crankshaft 166 oriented in the lateral direction of the motorcycle. The engine 36e is fixed to the motorcycle frame 152 and does not rotate therein. The engine 36e has a rear end portion, which supports a rear arm 168 pivotally in an up-down direction, and the rear arm 168 has a portion of

5 rear end, which supports a rear wheel 170. A seat 172 is disposed above the seat frame 158. The motorcycle frame 152 and the engine 36e have their left and right sides covered by a body cover 174.

[0123] Engine 36e includes a crankcase 176 incorporating a crankshaft 166 and a transmission (not illustrated); a cylinder body 44; a cylinder head 46 and a cylinder head cover 48. The cylinder body 44, the cylinder head 46 and the cover

of cylinder head 48 are identical to those included in engine 36.

[0124] The crankcase 176, the cylinder body 44, the cylinder head 46 and the cylinder head cover 48 are on a cylinder axis A of the engine 36e, in this order, from back to front, in the front-back direction of the motorcycle.

15 The crankcase 176, the cylinder body 44, the cylinder head 46 and the cylinder head cover 48 are connected to their adjacent members. The axis of the cylinder A is inclined in an oblique direction forward and upward with respect to the front-rear direction of the motorcycle. In this embodiment, the A axis is tilted slightly. In the motorcycle 10a, the rear wheel 170 is driven by a chain.

[0125] The cylinder head 46 has an upper surface connected to an air intake apparatus 178, which is

communicates with an air intake passage 74. In addition, like the engine 36 in Fig. 4, the cylinder head 46 has an overhanging portion 66 connected to an exhaust apparatus 56, which communicates with a gas passage of escape 80.

[0126] The motorcycle 10a that includes the engine 36e also provides the same advantages as the

provided by motorcycle 10.

[0127] It should be noted in this case that an engine such as engines 36a to 36d; a cylinder head cover

provided with a sensor cover as shown in Fig. 11 and Fig. 12; and a concentration sensor of

30 inclined oxygen with respect to the axis of the cylinder A, as shown in Fig. 15 and Fig. 16, can also be

apply to motorcycle 10a.

[0128] In the embodiments described above, there is no specific limitation for the angle formed by the axis of the cylinder A and the front-rear direction of the motorcycle. The angle can be a zero degree.

Specifically, the A-axis cylinder may be identical to the front-rear direction of the motorcycle. The present invention is applicable to a motor whose cylinder axis A is in the vertical or also essentially vertical direction. In addition, the engine according to the present invention can be of a liquid-cooled type.

[0129] The oxygen concentration sensor 50 may be mounted on the protruding portion 66 in such a way that the main body portion 118 is in a more rearward position than the portion of

detection 120. In this case, a front portion and a rear portion of the main body portion 118 are covered by the cylinder head 46 and the crankcase 42, respectively. A motorcycle mounted with an engine that has the oxygen concentration sensor 50 can protect the oxygen concentration sensor 50 properly, from bouncing stones, etc. coming from the road surface. The main body portion 118 included in the oxygen concentration sensor 50 may have a generally constant diameter. The diameter of the detection portion 120 may be different depending on its axial positions. This also applies to the oxygen concentration sensor 50a.

[0130] The oxygen concentration sensor employed in the present invention can be any of 50 type without heater and type equipped with heater. Even if the oxygen concentration sensor is

provided by a type equipped with a heater, the energy consumption by the oxygen concentration sensor can be reduced.

[0131] The recess formed along the oxygen concentration sensor on the outer circumferential surface 55 of the cylinder head is not limited to having a curved shape. For example, the recess may have a V-shaped form

by cutting the corner portion of the outer circumferential surface of the cylinder head in the direction of the cylinder axis.

[0132] The position of the exhaust gas passage formed in the cylinder head can be properly determined according to the design requirement for the saddle type vehicle in which the engine is mounted.

[0133] The protruding portion preferably protrudes at least in a downward direction, from the main head body. For example, when viewed in the direction of the cylinder axis, the protruding portion can protrude from the main body of the head in any oblique direction to the right and down; a

5 direction down; and an oblique direction to the left and down.

[0134] In the embodiments described above, the description was made for cases where the engines according to the present invention are applied to a scooter type motorcycle shown in Fig. 1, and to an underbone type motorcycle (a type of horizontal cylinder) shown in Fig. 18. However, the present invention is not limited to

10 these. The engine according to the present invention is applicable to motorcycles of other types, such as motorcycle type in which the engine is not of the horizontal cylinder type. In addition, the engine according to the present invention is applicable to any other saddle type vehicles including snowmobiles, all terrain vehicles, etc.

[0135] The application of the engine according to the present invention to a saddle-type vehicle makes it possible to reduce the increase in engine size and reduce the increase in the size of the saddle-type vehicle.

mount, even if the oxygen concentration sensor is provided in a position where the exhaust gas has a high temperature in the cylinder head.

[0136] The present invention is described to date in terms of preferred embodiments, it is obvious that these may vary in many ways within the scope and spirit of the present invention. The scope of the

The present invention is limited only by the appended claims.

25

30

35

40

Four. Five

 [LEGEND]

 [0137]

 10, 10a

 motorcycles

 36, 36a, 36b, 36c, 36d, 36e

 engines

 40

 crankshaft

 42

 sump

 44

 cylinder body

 46, 46a, 46b

 stock

 48

 cylinder head cover

 50, 50a

 oxygen concentration sensors

 65

 head head body

 66, 66

 protruding portions

 68

 recess

 70

 combustion recess

 72, 78, 78a

 opening portions

 79

 center of the opening portion

 80, 80a

 exhaust gas passages

 110

 cover mounting surface

 112, 112a

 sensor mounting surfaces

 118,118a

 main body portions

 120

 detection portion

 124, 124a, 124b

 electric cables

 140

 clamping portion

 144, 144a

 sensor cover portions

 TO

 cylinder shaft

 B

 central axis

Claims (14)

I. A single-cylinder or two-cylinder V engine, comprising: 5 a cylinder head (46; 46a; 46b) that includes a head main body (65) and an overhanging portion (66; 66a) protruding outward from the head head body (65), in which, when seen on an axis of the engine cylinder (A), the protruding portion (66; 66a) extends outwardly beyond the circumference of a cylinder head cover (48) mounted on the cylinder head (46; 46a; 46b) ; a combustion recess (70) formed in the main body of the head (65); 10 an exhaust gas passage (80; 80a) of the combustion recess (70) through the protruding portion (66; 66a) to evacuate the exhaust gas from the combustion recess (70); Y an oxygen concentration sensor (50; 50a) that includes a main body portion (118; 118a) and a detection portion (120) provided in the main body portion (118; 118a), to detect an oxygen concentration in the exhaust gases; fifteen wherein the oxygen concentration sensor (50; 50a) is mounted on the protruding portion (66; 66a), with the main body portion (118; 118a) and the detection portion (120) that overlap with the protruding portion (66; 66a) as seen in a direction of the cylinder axis, at least a portion of the detection portion (120) being located inside the exhaust gas passage (80; 80a), 20 in which neither the main body portion (118; 118a) nor the detection portion (120) leave the contour of the protruding portion (66; 66a) when viewed in the direction of the cylinder axis (A), and in which the oxygen concentration sensor (50; 50a) does not protrude beyond the main head body (65) in a left-right direction when viewed in the direction of the cylinder axis (A). 2. The engine according to claim 1, wherein the oxygen concentration sensor (50; 50a) as mounted on the protruding portion (66; 66a) has the main body portion (118; 118a) located in a more forward position than the detection portion (120). 3. The engine according to claim 1, wherein the oxygen concentration sensor (50; 50a) 30 as mounted on the protruding portion (66; 66a) has a central axis parallel to the axis of the cylinder (A). 4. The motor according to claim 1, wherein the protruding portion (66; 66a) protrudes from the main head body (65) at least in a downward direction. The motor according to claim 4, wherein the protruding portion (66; 66a) protrudes from the head head body (65) in an oblique direction downward when viewed in the direction of the cylinder axis (A). 6. The engine according to claim 1, wherein the protruding portion (66; 66a) has a 40 opening portion (78; 78a) as the downstream end of the exhaust gas passage (80; 80a), and a center of the opening portion (78, 78a) is not located on one side more to the outside than the main head body (65) in a left-right direction when viewed in the direction of the cylinder axis (A). 7. The motor according to claim 1, wherein the main head body (65) has a 45 outer circumferential surface with a recess (68) that is lowered into the main head body (65) as seen in the direction of the cylinder shaft (A), being the protruding portion (66; 66a) formed in the recess (68). 8. The motor according to claim 7, wherein the recess (68) is lowered upwards. fifty 9. The motor according to claim 7, wherein the recess (68) is lowered laterally. 10. The motor according to claim 7, wherein the recess (68) is formed as a recessed corner portion of the main head body (65). 55 II. The engine according to claim 1, wherein the cylinder head cover (48) is provided in front of the cylinder head (46; 46a; 46b); Y The engine further comprises a sensor cover portion (144; 144a) provided in the cylinder head cover (48) to cover at least a front portion of the main body portion (118; 118a). 5 10 fifteen twenty 25 30 12. The engine according to claim 1, wherein a cylinder head cover (48) is provided in front of the cylinder head (46; 46a; 46b), the cylinder head (46; 46a; 46b) has a cover mounting surface (110) for mounting the cylinder head cover (48), the protruding portion (66; 66a) has a sensor mounting surface (112; 112a) to mount the oxygen concentration sensor (50; 50a), The mounting surface of the cover (110) and the mounting surface of the sensor (112; 112a) are parallel to each other. 13. The engine according to claim 1, wherein a cylinder head cover (48) is provided in front of the cylinder head (46; 46a; 46b), the cylinder head (46; 46a; 46b) has a cover mounting surface (110) for mounting the cylinder head cover (48), the protruding portion (66; 66a) has a sensor mounting surface (112; 112a) to mount the oxygen concentration sensor (50; 50a), The mounting surface of the cover (110) and the mounting surface of the sensor (112; 112a) are in the same plane. 14. The engine according to claim 1, wherein the cylinder head cover (48) is provided in front of the cylinder head (46; 46a; 46b); Y The engine further comprises an electric cable (124; 124a; 124b) connected to the main body portion (118; 118a) and oriented along the head cover (48). 15. The motor according to claim 14, further comprising a clamping portion (140) provided in the head cover (48) for holding the electric cable (124; 124a; 124b). 16. A saddle type vehicle (10, 10a) comprising the engine according to one of claims 1 to 15. 17. The saddle type vehicle (10, 10a) according to claim 16, wherein the axis of the cylinder (A) is inclined in an oblique direction forward and upward.