Title of Invention

MOUNTING STRUCTURE OF OXYGEN SENSOR

Abstract To provide a mounting structure of an oxygen sensor which can reduce a cost while enhancing the layout property. [Means for Resolution] In arranging an oxygen sensor 150 without a heater for detecting oxygen density in an exhaust gas from an engine 110 on the engine 110 which includes a combustion chamber and an intake passage and an exhaust passage which are communicated with the combustion chamber, the oxygen sensor 150 is mounted on a straight portion 51A of an exhaust manifold 51C mounted on an exhaust opening 110A which is communicably connected with an exhaust port of the engine 110 in a state that the oxygen sensor 150 is mounted obliquely toward a downstream side from an upstream side of the an exhaust gas.
Full Text

[Designation of Document] Specification
[Title of the Invention] MOUNTING STRUCTURE OF OXYGEN SENSOR
[Technical Field]
[0001]
The present invention relates to the mounting structure of an oxygen sensor, and more particularly to the mounting structure of an oxygen sensor for detecting the oxygen density in the inside of an engine exhaust gas of a motorcycle. [Background Art] [0002]
In general, in a vehicle-use engine, from a viewpoint of enhancing the accuracy of fuel control, for purifying an exhaust gas or for achieving low fuel economy or the like, as a fuel supply device, there has been proposed a fuel supply device which adopts a fuel injection device in place of a carburetor (for example, see patent literature 1). Further, recently, there has been proposed a fuel supply device which adopts a fuel injection device in place of a carburetor also in a motorcycle.
The vehicle-use engine is expected to be designed and controlled such that the combustion of fuel can be performed as efficiently as possible. However, when an ideal combustion state is no more achieved due to fluctuation conditions such as an ambient temperature, an air-fuel mixture ratio or the like, an exhaust gas contains harmful carbon monoxide (CO) , nitrogen oxide (NOx) and unburnt hydrocarbon (HC).

Accordingly, with respect to the conventional vehicle-use engine, not to mention an accurate control of a ratio between air and fuel (an air-fuel mixture ratio; A/F) which uses an oxygen sensor made of stabilized zirconia, there has been proposed a vehicle-use engine which can reduce the carbon monoxide (CO), nitrogen oxide (NOx) or unburnt hydrocarbon (HC) in the inside of an exhaust gas by performing a control of an air inflow passage and mixing, an ignition timing control based of an electronic control or the like. [Patent Literature 1] JP-A-6-323187 [Disclosure of the Invention] [Problems that the Invention is to Solve] [0004]
Here, the oxygen sensor which uses the stabilized zirconia performs a detecting operation as follows. Oxygen contained in the exhaust gas receives electrons at an electrode and becomes oxygen ions. The oxygen ions pass through a zirconia layer and discharge the electrons and hence, the oxygen ions stay in the zirconia layer in a form of oxygen. The oxygen sensor detects a quantity of an electric current which is generated between electrodes in proportion to an oxidation/reduction reaction of oxygen as a quantity of an electric current which is proportional to the oxygen density.
The oxygen sensor which uses the stabilized zirconia

exhibits the extremely large inner resistance at a low temperature and hence, there has been a drawback that the movement of the oxygen ions is obstructed and the quantity of electric current becomes small. [0005]
Accordingly, conventionally, as the oxygen sensor, a heater-equipped oxygen sensor which includes a heater for heating an oxygen sensor body having a stabilized zirconia layer has been used.
However, the heater-equipped oxygen sensor becomes large-sized in shape thus giving rise to a drawback that the layout property is worsened and a cost is pushed up in mounting the oxygen sensor on a motorcycle.
Accordingly, it is an object of the present invention to provide the mounting structure of an oxygen sensor which can reduce a cost while ensuring high layout property. [Means for Solving the Problem] [0006]
To overcome the above-mentioned drawback, in a mounting structure of an oxygen sensor which arranges the oxygen sensor for detecting oxygen density in an exhaust gas from an engine on the engine, the present invention is characterized in that the oxygen sensor is arranged on an exhaust manifold which is mounted on an exhaust opening of the engine in the vicinity of the exhaust opening.

Due to such a constitution, the oxygen sensor speedily arrives at an optimum temperature to perform the detection of the oxygen density using a high-temperature exhaust gas and can perform an accurate measurement of the oxygen density speedily and optimumly. [0007]
In this case, the oxygen sensor may have an oxygen detecting side and a wiring side and may allow the wiring side to be arranged on a head side of the engine*
Further, the exhaust manifold may have a bent portion at an intermediate portion thereof, and the oxygen sensor may be arranged in the inside of the bent portion.
Still further, the oxygen sensor may be constituted as an oxygen sensor without a heater. [Advantage of the Invention] [0008]
According to the present invention, an oxygen sensor is arranged on the exhaust manifold which is mounted on the exhaust port of the engine in the vicinity of the exhaust port where a temperature of the exhaust gas is relatively high and hence, the oxygen sensor speedily arrives at an activation temperature region at the time of driving the engine whereby it is possible to detect oxygen density in the exhaust gas speedily and accurately. [Best Mode for Carrying Out the Invention]

Next, preferred embodiments of the present invention are explained in conjunction with the drawings.
In the following explanation, "front", "rear", "left", "right", "up", "down" are determined in accordance with directions as viewed from a rider and Fr indicates a front side, Rr indicates a rear side, L indicates a left side, andR indicates a right side. [0010]
Fig. 1 is a left side view of a motorcycle of an embodiment of the present invention.
A motorcycle 10 is a scooter-type vehicle. The motorcycle 10 includes a vehicle body frame 11, a front fork 13 which is mounted on a head pipe 12 of the vehicle body frame 11, a front wheel 14 which is mounted on the front fork 13, a handle 15 which is connected to the front fork 13, a swing-type power unit 16 which is mounted on a rear upper portion of the vehicle body frame 11, a rear wheel 17 which is mounted on a rear portion of the power unit 16, a rear suspension 18 which suspends the power unit 16 on the rear upper portion of the vehicle body frame 11, a storing portion 21 which is mounted on the rear upper portion of the vehicle body frame 11, a seat 22 which is mounted on an upper portion of the storing portion 21, a fuel tank 23 which is arranged behind the storing portion 21 and is mounted on the rear upper portion of the vehicle body

frame 11, and a body cover 30 which covers the vehicle body frame 11.
The storing portion 21 is formed as a storing box which stores various articles P such as a helmet or the like. [0011]
The body cover 30 includes a front cover 31 which covers a front portion of the head pipe 12, a leg shield 32 which covers a leg portion of a rider, a step floor 33 which allows the rider to place his feet thereon, an under cover 34 which is arranged below the step floor 33 and covers a lower portion of the vehicle body frame 11, and a rear side cover 35 which covers a rear half portion of the vehicle body frame 11.
Further, the motorcycle 10 includes a front suspension 41, a head lamp 42, a meter 43, a front fender 44, a handle cover 45, a main stand 46 and a rear fender 47. [0012]
Fig. 2 is a side view of a rear portion of a motorcycle of this embodiment in an enlarged manner.
The vehicle body frame 11 is constituted as a two-split frame which is divided in two in the fore/and/aft direction into a front frame 60 which forms a front portion of the vehicle body frame 11 and a rear frame 70 which forms a rear portion of the vehicle body frame 11 below the step floor 33. A sub frame 80 is fixed to a rear end portion of the rear frame 70 using bolts.
The power unit 16 is arranged below the storing portion

21 and the seat 22. The power unit 16 includes an engine 110 which is arranged at a front portion thereof and a continuously variable transmission 171 which is arranged at a rear portion thereof. The engine (internal combustion engine) 110 is constituted of a four-cycle single-cylinder water-cooled type engine in which cylinders are arranged substantially horizontally in the frontward direction of the vehicle body, while the continuously variable transmission 171 is constituted as a belt-type transmission. [0013]
In Fig.2, an air cleaner 131 is mounted on a left side of the rear wheel 17 and on a rear upper portion of the power unit 16.
Further, an exhaust pipe 51 for engine and a muffler 52 are connected to an exhaust opening 110A which is communicably mounted to an exhaust port of the engine 110.
The exhaust pipe 51 for engine includes a straight pipe portion 51A and bent portion 51B. The engine-use exhaust pipe 51 also includes an exhaust manifold 51C which is connected to the exhaust opening 110A communicably connected to the exhaust port and an exhaust pipe 51D which is connected to the exhaust manifold 51C. [0014]
Fig. 3 is a plan view of a rear portion of a motorcycle of this embodiment in an enlarged manner.

In Fig. 3, a radiator 53 for engine is integrally mounted on a right side of the power unit 16.
Further, the sub frame 80 includes left and right erected accommodating posts 81, 81 and a connecting stay 82 which connects the accommodating posts 81, 81, while a spark plug 54 is arranged on a left side of the cylinder head 115. [0015]
Fig. 4 is a side view showing a periphery of the power unit.
In the engine 110, the cylinder block 112 and the cylinder (not shown in the drawing) arranged in the inside of the cylinder block 112 extend substantially horizontally toward a front portion of the vehicle body from the crankcase 111, wherein a cylinder head 115 is fixedly joined to a front end of the cylinder block 112 using bolts. Further, in the engine 110, a head cover 117 is fixedly joined to a front end of the cylinder head 115 using bolts. [0016]
An air intake system 130 of the engine 110 includes, as shown in Fig. 4, an air cleaner 131, a connecting pipe 132 (connection pipe) which is connected to an outlet of the air cleaner 131, a throttle body 133 which is connected to a downstream end of the connecting pipe 132, an inlet pipe 134 which is connected to a downstream end of the throttle body 133, and an air intake passage 122 which is connected to a downstream

end of the inlet pipe 134,
In the air intake system 130, the air cleaner 131, the connecting pipe 132, the throttle body 133 and the inlet pipe 134 are arranged above the engine 110 in a substantially horizontal state from the rear portion to the front portion of the vehicle body. Further, a downstream end of the inlet pipe 134 is connected to the air intake passage 122 of the engine 110. [0017]
The throttle body 133 is connected to the upstream end of the inlet pipe 134 and, at the same time, is arranged substantially above the crankcase 111. Further, the throttle body 133 incorporates a throttle valve 135 therein. The throttle valve 135 is arranged on an upstream side of the intake passage 122 and controls a cross-sectional area of a flow passage of the intake passage 122.
A fuel injection device 140 is arranged above the cylinder head 115. The fuel injection device 140 is an injector which injects fuel in response to an injection signal which is obtained by the calculation of an electronic control unit not shown in the drawings. The fuel injection device 140 includes, for example, a solenoid—actuated-valve nozzle. A feed pipe 142 is mounted by fitting engagement on a fuel inlet portion of an upper end of the fuel injection device 140. A fuel hose 146 is connected to the fuel injection device 140 through the feed

pipe 142. [0018]
The exhaust opening 110A which is communicably connected to the above-mentioned exhaust port is arranged below the cylinder head 115. On a bent portion 51Aof the exhaust manifold 51C which is connected to the exhaust opening 110A communicably connected to the exhaust port, an oxygen sensor 150 is mounted, wherein the oxygen sensor 150 detects an oxygen density in the exhaust gas from the engine 110 and allows an optimum air-fuel ratio control in an electronic control unit not shown in the drawing. [0019]
Here, the structure of the oxygen sensor 140 is explained.
Fig. 5 is a cross-sectional view of the oxygen sensor, while Fig. 6 is a view as a viewed in an arrow direction from a cross-sectional end surface taken along a line A-A in Fig. 5.
An oxygen sensor 150 is constituted as a oxygen sensor without a heater. The oxygen sensor 150 includes a holder 151 for supporting the whole of the oxygen sensor 150 at the time of mounting the oxygen sensor 150 on the exhaust manifold 51C.
A flange portion 151A is mounted on an intermediate portion of an outer periphery of the holder 151 and a threaded portion 151B for mounting is formed on a distal end portion of the holder 151.

On a distal end side of the inside of the holder 151, a zirconia pipe 152 is held/ wherein platinum which constitutes an electrode is applied to portions of inner and outer surfaces of the zirconia pipe 152 . Here, the zirconia pipe 152 is formed using, for example, zirconium oxide (Zr02) as a main component. A periphery of the zirconia pipe 152 is covered with a protector 153 which has a plurality of holes 154A. The protector 153 has the duplicate structure composed of an outer cylinder 154 and an inner cylinder 155, wherein a filter 156 for catching harmful articles is arranged between the outer cylinder 154 and the inner cylinder 155. Ametallic contact plate 157 is mounted on a proximal end portion of the zirconia pipe 152. [0021]
A surface side (left side, in Fig. 5) of the contact plate 157 is electrically connected to the zirconia pipe 152 in a state that a distal end portion of a ceramic insulation bush 158 which is fixed in the proximal end portion of the holder 151 is brought into contact with a surface side of the contact plate 157.
On the other hand, a lead line portion 159 is electrically connected to a back surface side (right side, in Fig. 5) of the contact plate 157. The insulation bush 158 and the lead line portion 159 are covered with a casing 160 which is fitted on the holder 151. Further, an output signal line 161 is led out from one end of the casing 160.

In the oxygen sensor 150, the atmospheric air is introduced as a reference gas to an inner surface 152A side of the zirconia pipe 152 and an exhaust gas which constitutes an object to be detected is introduced to an outer surface 152B side. As a result, an electromotive force corresponding to a ratio between the oxygen density in the atmospheric air and the oxygen density in the exhaust gas is generated between platinum coated electrodes.
To be more specific, the oxygen ions move from the atmospheric air side which exhibits high oxygen partial voltage to the exhaust gas side thus generating an electromotive force. This electromotive force is increased along with the increase of the concentration difference. [0023]
Accordingly, an air-fuel ratio is controlled in an optimum manner corresponding to the oxygen density in the exhaust gas which is detected by an electric control unit not shown in the drawing in response to a detection signal which is outputted to an output signal line 161 based on the electromotive force.
Further, the zirconia pipe 152 which constitutes the oxygen sensor 150 exhibits an extremely large inner resistance at a low temperature and hence, the movement of oxygen ions is interrupted and the electromotive force is decreased whereby

the measurement error is increased, or it is impossible to
perform the measurement per se.
[0024]
Next, the mounting structure of the oxygen sensor is explained.
Fig. 7 is an explanatory view showing a mounting state of the oxygen sensor.
As shown in Fig. 7, the oxygen sensor 150 is threaded into a mounting portion 51E which is formed on the straight pipe portion 51A of the exhaust manifold 51C. Here, the flange portion 151A of the holder 151 of the oxygen sensor 150 is brought into contact with an end surface of the mounting portion 51E. [0025]
Accordingly, the oxygen sensor 150 is mounted on the exhaust manifold 51C in the vicinity of the exhaust opening 110A which is communicably connected to the exhaust port and hence, in spite of the fact that the oxygen sensor without a heater is used as the oxygen sensor 150, it is possible to speedily heat the zirconia pipe 152 using a high-temperature exhaust gas and to quickly perform the accurate measurement. [0026]
Further, the oxygen sensor 150 uses the sensor without a heater and hence, it is possible to reduce a cost and, at the same time, a size of the oxygen sensor can be miniaturized by an amount corresponding to the non-presence of the heater in

the sensor whereby the oxygen sensor is applicable to a motorcycle or the like which is required to satisfy a demand for further compactness and receives the restriction on a layout thereof. Further, it is also unnecessary to provide a control circuit for controlling a heater and hence, a control can be simplified and a cost can be also reduced. [0027]
Fig. 8 is an explanatory cross-sectional view showing a mounting state of the oxygen sensor.
As shown in Fig. 8, a mounting portion 51E is formed on a straight pipe portion 51A of an exhaust manifold 51C by welding, and on an inner peripheral surface of the mounting portion 51E, a threaded portion 51F (female threads) which corresponds to a threaded portion 151B (male threads) of the oxygen sensor 150 is formed.
Here, the mounting portion 51E is obliquely welded to the straight pipe portion 51A of the exhaust manifold 51C, and the oxygen sensor 150 has, in a mounted state, a protector 153 side (oxygen detection side) obliquely inserted in the inside of the exhaust manifold 51C in a state that the protector 153 side (oxygen detection side) is directed toward a downstream side from an upstream side of the exhaust gas (the direction of an arrow X in Fig. 8) . That is, an output signal line 161 side (wiring side) of the oxygen sensor 150 is positioned on the cylinder head 115 side of the engine 110.

Accordingly, the oxygen sensor 150 can be mounted in the straight pipe portion 51 of the manifold 51C where the flow of the exhaust gas has the little turbulence and, at the same time, the oxygen sensor 150 has, in a mounted state, the protector 153 side (oxygen detection side) obliquely inserted in the inside of the exhaust manifold 51C in a state that the protector 153 side is directed toward a downstream side from an upstream side of the exhaust gas (the direction of the arrow X in Fig. 8) and hence, the flow passage resistance of the exhaust gas in the inside of the exhaust manifold 51C can be reduced whereby the flow of the exhaust gas is not interrupted and the accurate measurement of the oxygen density can be performed, [0029]
Further, to compare a case that the oxygen sensor 150 is mounted on the outer peripheral surface of the exhaust manifold 51C in a vertical manner, it is possible to reduce an amount of a projection of the oxygen sensor 150 in the sideward direction of the motorcycle 10. Accordingly, wiring of an output signal line 161 is facilitated and, at the same time, a mounting space can be reduced. Particularly, it is possible to obtain these advantageous effects in vehicles which can not ensure a large mounting space as a motorcycle (including a three-wheeled vehicle).

As has been explained above, according to this embodiment, even when the oxygen sensor without a heater is adopted as the oxygen sensor, it is possible to allow the zirconia pipe to arrive at the optimum given temperature for measurement using the exhaust gas. Accordingly, in spite of the fact that the oxygen sensor without a heater is adopted, it is possible to quickly start the detection of the oxygen density. [0031]
Further, by adopting the oxygen sensor 150 without the heater, it is possible to reduce the cost and, at the same time, a size of the oxygen sensor can be miniaturized by an amount corresponding to the non-presence of the heater in the sensor whereby the oxygen sensor is also applicable to a motorcycle or the like which is required to satisfy a demand for further compactness and receives the restriction on a layout thereof compared with a four-wheeled vehicle. Further, it is also unnecessary to provide a control circuit for controlling a heater and hence, a control can be simplified and a cost can be also reduced. [0032]
In the explanation described above, the oxygen sensor 150 is mounted on the straight pipe portion 51A of the exhaust manifold 51C connected to the exhaust opening 110A which is communicably connected to the exhaust port. However, it is possible to allow the oxygen sensor 150 to be mounted on the

exhaust opening 110A which is communicably connected to the
exhaust port.
[Brief Description of the Drawings]
[0033]
[Fig. 1]
A left side view of a motorcycle of the embodiment. [Fig. 2]
A side view of a rear portion of a motorcycle of this embodiment in an enlarged manner. [Fig. 3]
A plan view of a rear portion of a motorcycle of this embodiment in an enlarged manner. [Fig. 4]
A side view showing a periphery of the power unit. [Fig. 5]
A cross-sectional view of the oxygen sensor. [Fig. 6]
A view as viewed in an arrow direction from a cross-sectional end surface taken along a line A-A in Fig. 5. [Fig. 7]
An explanatory view showing a mounting state of the oxygen sensor. [Fig. 8]
An explanatory view showing a mounting state of the oxygen sensor in a cross-sectional manner.

[Description of Reference Numerals and Signs]
[0034]
10: motorcycle
11: vehicle body frame
16: swing-type power unit
21: storing portion
22: seat
51A: straight pipe portion
51B: bent portion
51C: exhaust manifold
51D: exhaust pipe
51E: mounting portion
110: engine
110A: exhaust opening
111: crankcase
112: cylinder block
113: cylinder
115: cylinder head
116: combustion chamber
121: intake valve
122: intake passage
122a: upstream end of intake passage
128: coolant passage
130: intake system
131: air cleaner

132: connecting pipe
133: throttle body
134: inlet pipe
135: throttle valve
140: fuel injection device
150: oxygen sensor
151: holder
151A: flange portion
152: zirconia pipe
153: protector
154: outer cylinder
155: inner cylinder
156: filter
157: contact plate
158: insulation bushing
159: lead line portion
160: casing
161: output signal line
171: belt-type continuously variable transmission


[Designation of Document] Claims [Claim 1]
A mounting structure of an oxygen sensor which arranges the oxygen sensor for detecting oxygen density in an exhaust gas from an engine on the engine, wherein
the oxygen sensor is arranged on an exhaust manifold which is mounted on an exhaust opening of the engine in the vicinity of the exhaust opening. [Claim 2]
A mounting structure of an oxygen sensor according to claim 1, wherein
the oxygen sensor includes an oxygen detection side, and the oxygen detection side is inserted in the inside of the exhaust manifold obliquely from an upstream side to a downstream side of the exhaust opening. [Claim 3]
A mounting structure of an oxygen sensor according to claim 1 or claim 2, wherein
the exhaust manifold has a straight pipe portion which is positioned on the exhaust opening side and a bent portion which is continuously connected with the straight pipe portion, and
the oxygen sensor is arranged on the straight pipe portion. [Claim 4]

Amounting structure of an oxygen sensor according to any of claim 1 to claim 3, wherein
the oxygen sensor is constituted of an oxygen sensor without a heater.


Documents:

1857-CHE-2005 AMENDED PAGES OF SPECIFICATION 14-10-2011.pdf

1857-CHE-2005 AMENDED CLAIMS 14-10-2011.pdf

1857-CHE-2005 EXAMINATION REPORT REPLY RECEIVED 14-10-2011.pdf

1857-CHE-2005 POWER OF ATTORNEY 14-10-2011.pdf

1857-CHE-2005 CORRESPONDENCE PO.pdf

1857-CHE-2005 FORM-18.pdf

1857-CHE-2005 FORM-3.pdf

1857-che-2005-abstract.pdf

1857-che-2005-claims.pdf

1857-che-2005-correspondnece-others.pdf

1857-che-2005-description(complete).pdf

1857-che-2005-drawings.pdf

1857-che-2005-form 1.pdf

1857-che-2005-form 3.pdf

1857-che-2005-form 5.pdf

1857-che-2005-other-documents.pdf


Patent Number 249771
Indian Patent Application Number 1857/CHE/2005
PG Journal Number 45/2011
Publication Date 11-Nov-2011
Grant Date 09-Nov-2011
Date of Filing 19-Dec-2005
Name of Patentee HONDA MOTOR CO., LTD.
Applicant Address 1-1 MINAMIAOYAMA 2-CHOME, MINATO-KU, TOKYO, JAPAN
Inventors:
# Inventor's Name Inventor's Address
1 KONO, TOMOYA C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN
2 YAMAZAKI, RYUTARO C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN
3 URAKI, MAMORU, C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN
4 HAYASHI, TATSUO C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN
5 TAKEDA, TORU C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN
6 ABE, TAKERU C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN
7 . .
PCT International Classification Number B60R11/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2004-367474 2004-12-20 Japan