| Title of Invention | EXHAUST GAS SENSOR MOUNT STRUCTURE FOR MOTORCYCLE |
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| Abstract | To provide an exhaust gas sensor mount structure which prevents interference between the down frame to the front of the cylinder and the exhaust gas sensor for a motorcycle provided with a body frame including a main frame extending rearward from the head pipe and the down frame extending downward from the head pipe, the engine supported below the main frame and to the rear of the down frame, the cylinder of the engine extending in substantially the upward direction, and the exhaust pipe connected to the exhaust port disposed on the front surface of the cylinder head. [Solution] The exhaust port extends in one of left and right directions of the vehicle body, and in the lower front direction of the vehicle body. The exhaust gas sensor is attached to the cylinder head to the rear of the down frame having the axis extending in the upper front direction from the exhaust port in the other of the left and the right directions with respect to the exhaust port. [Selected Drawing] Fig. 4 |
| Full Text | [Document Name] Specification [Title of the Invention] EXHAUST GAS SENSOR MOUNT STRUCTURE FOR MOTORCYCLE [Technical Field] [0001] The present invention relates to an exhaust gas sensor mount structure of an internal combustion engine for a motorcycle. [Background Art] [0002] The structure having an exhaust gas sensor disposed in a cylinder head of a horizontal opposed engine supported with a body frame of a scooter type vehicle has been disclosed (for example, see Patent Document 1). The sensor may be installed in the scooter type vehicle with no problem. However, in the case where the exhaust gas sensor is installed in the frame of the two-wheeled vehicle having the down frame to the front of the cylinder, the exhaust gas sensor becomes so close to the down frame that it is difficult to dispose the exhaust gas sensor. [0003] [Patent Document 1] JP-A No. 2004-316430 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0004] It is an object of the present invention to provide a structure which allows the exhaust gas sensor to be mounted in a vehicle provided with the down frame to the front of the cylinder even if the down frame is disposed adjacent to the exhaust gas sensor. [Means for Solving the Problem] [0005] The present invention has been made to solve the aforementioned problems. The present invention according to Claim 1 provides an exhaust gas sensor mount structure for a motorcycle which includes a body frame including a main frame extending rearward from a head pipe, and a down frame extending downward from the head pipe, an engine supported below the main frame and to the rear of the down frame, a cylinder of the engine extending in substantially an upward direction, and an exhaust pipe connected to an exhaust port disposed on a front surface of the cylinder head. The exhaust port extends in one of left and right directions of the vehicle body to a lower front of the vehicle body. The exhaust gas sensor is attached to the cylinder head to the rear of the down frame, having an axis extending in an upper front direction from the exhaust port in the other direction of the left and the right with respect to the exhaust port. [0006] In the exhaust gas sensor mount structure for a motorcycle of Claim 2 according to Claim 1, the exhaust gas sensor is a sensor for detecting O2. Air-cooled fins orthogonally protruding in an axial direction of the cylinder head are formed on an outer circumference of the cylinder head to define a non-fin portion as a ^3 discontinuous part of the air-cooled fins, and the O2 sensor is at least partially disposed in the non-fin portion. [0007] In the exhaust gas sensor mount structure for a motorcycle of Claim 3 according to Claim 1 or 2, an inner diameter defined by an outlet of the exhaust port and an exhaust gas sensor mount through hole for mounting the exhaust gas sensor is formed as a true circle. [0008] In the exhaust gas sensor mount structure for a motorcycle of Claim 4 according to Claims 1 to 3, a guard which covers a front portion of the exhaust gas sensor mount portion is provided integrally with the cylinder head. [0009] In the exhaust gas sensor mount structure for a motorcycle of Claim 5 according to Claims 2 to 4, the O2 sensor is exposed in the exhaust port outside a bent portion of the exhaust port. [Effect of the Invention] [0010] In the invention according to Claim 1, the exhaust gas sensor is tilted to the left or the right to be directed to the upper front so as to reduce the protruding amount of the exhaust gas sensor from the cylinder head. This makes it possible to dispose the exhaust gas sensor between the down frame and the cylinder while bringing the down frame to be close to the cylinder. [0011] In the invention according to Claim 2, an O2 sensor is disposed in the non-fin portion as the discontinuous part of the air-cooled fins to further reduce the protruding amount of the O2 sensor. The fin which exhibits the cooling function is removed to rapidly raise the temperature around the O2 sensor. As a result, the time for starting the O2 sensor provided with no heater until it is heated to the applied temperature may be shortened. The dew is hardly formed by the use of the O2 sensor with no heater, thus preventing dew formation around the exhaust port. [0012] In the invention according to Claim 3, in the case where the exhaust port is formed using the sand mold, the amount of change in the exposure length of the exhaust gas sensor owing to mismatch of the mold may be suppressed as least as possible. [0013] In the invention according to Claim 4, the exhaust gas sensor mount portion may be prevented from being hit with the stone without increasing the number of components for preventing vandalizing by covering the fastened portion of the exhaust gas sensor. [0014] In the invention according to Claim 5, as the exhaust gas at the high flow rate impinges against the O2 sensor, the high temperature exhaust gas may serve to activate the O2 sensor, thus improving the detection accuracy. [0015] Fig, 1 is a side view of a motorcycle 2 having an engine 1 according to an embodiment of the present invention mounted thereon. A body frame of the motorcycle 2 includes a head pipe 3, a main frame 4 which extends diagonally rearward from the head pipe 3, a center frame 5 which extends downward from the rear end of the main frame 4, a down frame 6 which extends downward from the head pipe 3, a seat stay 7 which extends rearward from the main frame 4, and a mid-frame 8 which connects the lower end of the center frame 5 to the center of the seat stay 7. A front fork 10 for supporting a front wheel 9 is steerably supported with the head pipe 3. A steering handlebar 11 is connected to the front fork 10. A rear fork 13 for supporting a rear wheel 12 is swingably supported in the vertical direction with the rear portion of the center frame 5. A cushion unit 14 is interposed between the seat stay 7 and the rear fork 13. The engine 1 is supported with the down frame 6, the main frame 4, and the center frame 5. The power of the engine 1 is transmitted to the rear wheel 12 via a rear wheel drive chain 15, The main frame 4 is provided with a fuel tank 16 above the engine 1. A tandem seat 17 for the rider and the pillion passenger is attached onto the seat stay 7. An air-cooled oil cooler 18 is disposed to the left front of the engine 1. An exhaust pipe 19 extends from the engine to be bent downward, and further extends rearward to be connected to a muffler 20 at the rear portion. [0016] Fig. 2 is a side view showing the cross-section of the center of the engine 1 in the lateral direction. The engine 1 is formed by integrally assembling an internal combustion engine 21 with a transmission 22. The engine 1 includes left and right half-body type crankcases 23L and 23R, and left and right crankcase covers 24L and 24R outside those crankcases. The drawing shows the left crankcase 23L and the abutment surface 23a while removing the right crankcase 23R. The drawing further shows a crankshaft 25, a main shaft 26 of the transmission, a countershaft 27 of the transmission, cross-sections of a shift rod 28 and a shift drum 29, and a shift fork 30. [0017] A cylinder block 33, a cylinder head 34, and a cylinder head cover 35 are connected to the upper surface of the crankcase 23. The drawing shows the inside of those components. A piston 38 is connected to a crank pin 36 communicated with the crankshaft 25 via a connecting rod 37 A combustion chamber 60 is formed on the lower surface of the cylinder head 34 opposite the upper surface of the piston 38. The leading end of an externally installed spark plug 61 (Fig. 5) is in the combustion chamber 60. The cylinder head 34 contains an intake port 39, an exhaust port 40, an intake valve 41 and an exhaust valve 42. A valve train 43 is provided at a boundary between the cylinder head 34 and the cylinder head cover 35. The valve train 43 includes a camshaft 44, an intake rocker shaft 45, an exhaust rocker shaft 46, an intake rocker arm 47, and an exhaust rocker arm 48. An O2 sensor mount through screw hole 54b is shown inside the exhaust port 40. [0018] Fig. 3 is a top view of the cylinder head 34 having the cylinder head cover 3 5 and the valve train 4 3 removed. The arrow F represents the forward direction. The drawing shows four stud bolt insertion holes 49 for connecting the crankcase 23, the cylinder block 33 and the cylinder head 34, the head of a valve stem 41a of the intake valve, the head of a valve stem 42a of the exhaust valve, and the upper opening of a cam chain chamber 50. An exhaust pipe mount portion 51 is disposed to the front of the cylinder head 34. An exhaust pipe mount axis 51a is tilted to the right with respect to the forward direction. An O2 sensor mount portion 54 is disposed on the upper outer surface of the exhaust pipe mount portion 51. The O2 sensor mount through screw hole 54b which penetrates from the O2 sensor mount portion 54 to reach the inside of the exhaust port 40 is formed. The O2 sensor mount axis 54a is tilted upward to the left with respect to the forward direction. A guard 55 for covering the front of the O2 sensor mount portion 54 is integrally provided with the cylinder head (see Fig. 2). The O2 sensor mount portion 54 defines a non-fin portion 34a as a discontinuous part of the air-cooled fins 56 to be disposed therein. An O2 sensor an oxygen detection sensor 53 is further disposed in the non-fin portion 34a of the air-cooled fins 56. Fig. 4 is a front view of the cylinder head 34 showing the state where the O2 sensor 53 is mounted. The O2 sensor mount portion 54 is formed on the outer surface of the exhaust pipe mount portion 51, having the exhaust pipe mount axis 51a directed to the right. Meanwhile, an O2 sensor mount axis 54a is directed diagonally upward to the left. The guard 55 for protecting the O2 sensor mount portion 54 is disposed to the front thereof. The O2 sensor mount portion 54 and the O2 sensor 53 define the non-fin portion 34a as the discontinuous part of the air-cooled fins 56 to be disposed therein. [0020] Fig. 5 is a perspective view of the O2 sensor mount portion 54. The cylinder block 33, the cylinder head 34, and the cylinder head cover 3 5 are connected to the upper portion of the crankcase 23. The down frame 6 supports the front of the engine 1. The air-cooled oil cooler 18 is disposed to the left front of the cylinder head 34. A cooling system forward oil passage 58 and a cooling system return oil passage 59 are connected between the right crankcase cover 24R and the oil cooler 18. The exhaust pipe 19 is attached to the right front surface of the cylinder head 34, which is bent downward. The O2 sensor mount portion 54 is provided at the upper left of the exhaust pipe mount portion 51 on which the O2 sensor 53 is mounted. The guard 55 for protecting the O2 sensor mount portion 54 is disposed to the front of the components. The O2 sensor mount axis 54a extends to the left as the 3P^ different direction from that of the exhaust pipe mount axis 51a, and further extends outward directed upper front of the vehicle body. As a result, the adjacent down frame 6 does not interfere with the axis. The O2 sensor 53 positioned right behind the down frame 6 is protected thereby. The O2 sensor mount portion 54 and the O2 sensor 53 define the non-fin portion 34a as the discontinuous part of the air-cooled fins 56 so as to be disposed therein. The spark plug is hinged to the right side of the cylinder head 34. [0021] The structure for mounting the O2 sensor 53 of a motorcycle according to the embodiment provides the following effects. (1) As the O2 sensor 53 is tilted to the left and directed to the upper front to reduce the protruding amount of the O2 sensor 53 from the cylinder head 34, the interference between the down frame 6 and the O2 sensor 53 may be avoided even if the down frame 6 is brought to be close to the•cylinder. (2) As the air-cooled fins 56 are partially removed to accommodate the O2 sensor mount portion 54, the protruding amount of the O2 sensor may be decreased. As the air-cooled fins 56 with the cooling function are partially removed, the temperature around the O2 sensor 53 may be rapidly increased to reduce the time for starting the O2 sensor 53 with no heater until it is heated to the applied temperature. When the O2 sensor 53 with no heater is employed, the dew is hardly formed, and accordingly, the dew formation around the exhaust port may be prevented. (3) The inner diameter defined by the outlet of the exhaust port 40 and the O2 sensor mount through screw hole 54b is formed as a true circle to suppress the change in the exposure length of the O2 sensor 53 caused by the mismatch of the sand mold for forming the exhaust port as least as possible. (4) As the guard 55 for covering the front of the O2 sensor mount portion 54 is integrally formed with the cylinder head 34, the O2 sensor mount portion 54 may be protected from being hit with the stone without increasing the number of components. The O2 sensor 53 is structured not to be easily removed unless the screw wrench is used, thus preventing vandalizing. (5) As the O2 sensor 53 is disposed to be exposed outside the bent portion of the exhaust port 40, the exhaust gas at high rates impinges against the O2 sensor 53 so as to be activated with the high temperature exhaust gas, thus improving the detection accuracy. (6) In the embodiment, the mount structure of the O2 sensor 53 has been described as an example of the mount structure of the exhaust gas sensor. However, other type of the mount structure of the exhaust gas sensor may provide the similar effects. [Brief Description of the Drawings] [0045] [Fig. 1] Fig. 1 is a side view of a motorcycle provided with an engine according to an embodiment of the present invention. [Fig. 2] Fig. 2 is a side view showing the cross-section of the center of the engine in the lateral direction. [Fig. 3] Fig. 3 is a top view of the cylinder head of the engine having the cylinder head cover and the valve train of the engine removed. [Fig. 4] Fig. 4 is a front view of the cylinder head showing the state where the O2 sensor is mounted. [Fig. 5] Fig. 5 is a perspective view of the O2 sensor mount structure. [0034] 1... Engine 2... Motorcycle 3... Head pipe 4... Main frame 5... Center frame 6... Down frame 1... Seat stay 8... Mid-frame 19... Exhaust pipe 23... Crankcase 24... Crankcase cover 33... Cylinder block 34... Cylinder head 34a... Non-fin portion 35... Cylinder head cover 3 9... Intake port 40... Exhaust port 41... Intake valve 42... Exhaust valve 43... Valve train 51... Exhaust pipe mount portion 51a... Exhaust pipe mount axis 53... O2 sensor 54... O2 sensor mount portion 54a... O2 sensor mount axis 54b.,. O2 sensor mount through screw hole 55... Guard 56... Air-cooled fin [Document Name] Scope of Claim [Claim 1] An exhaust gas sensor mount structure for a motorcycle, comprising: a body frame including a main frame extending rearward from a head pipe, and a down frame extending downward from the head pipe; an engine supported below the main frame and to the rear of the down frame; a cylinder of the engine extending in substantially an upward direction; and an exhaust pipe connected to an exhaust port disposed on a front surface of the cylinder head, wherein: the exhaust port extends in one of left and right directions of the vehicle body to a lower front of the vehicle body; and the exhaust gas sensor is attached to the cylinder head to the rear of the down frame, having an axis extending in an upper front direction from the exhaust port in the other direction of the left and the right with respect to the exhaust port. [Claim 2] The exhaust gas sensor mount structure for a motorcycle according to Claim 1, wherein:the exhaust gas sensor is a sensor for detecting O2; and air-cooled fins orthogonally protruding in an axial direction of the cylinder head are formed on an outer circumference of the cylinder head to define a non-fin portion as a discontinuous part of the air-cooled fins, and the O2 sensor is at least partially disposed in the non-fin portion. [Claim 3] The exhaust gas sensor mount structure for a motorcycle according to Claim 1 or 2, wherein an inner diameter defined by an outlet of the exhaust port and an exhaust gas sensor mount through hole for mounting the exhaust gas sensor is formed as a true circle. [Claim 4] The exhaust gas sensor mount structure for a motorcycle according to Claims 1 to 3, wherein a guard which covers a front portion of the exhaust gas sensor mount portion is provided integrally with the cylinder head. [Claim 5] The exhaust gas sensor mount structure for a motorcycle according to Claims 2 to 4, wherein the O2 sensor is exposed in the exhaust port outside a bent portion of the exhaust port. |
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| Patent Number | 271994 | ||||||||
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| Indian Patent Application Number | 1511/CHE/2009 | ||||||||
| PG Journal Number | 12/2016 | ||||||||
| Publication Date | 18-Mar-2016 | ||||||||
| Grant Date | 14-Mar-2016 | ||||||||
| Date of Filing | 26-Jun-2009 | ||||||||
| Name of Patentee | HONDA MOTOR CO., LTD. | ||||||||
| Applicant Address | 1-1, MINAMI-AOYAMA 2-CHOME, MINATO-KU, TOKYO 107-8556 | ||||||||
Inventors:
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| PCT International Classification Number | B60N 2/00 | ||||||||
| PCT International Application Number | N/A | ||||||||
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