Title of Invention

EXHAUST EMISSION CONTROL SYSTEM FOR MOTORCYCLE

Abstract

The present invention provides an exhaust emission control system including an exhaust gas passage of an internal combustion engine in a power unit that is integrally composed of the internal combustion engine and a transmission; an upstream catalyst arranged at the upstream side of the exhaust gas passage; a downstream catalyst arranged at the downstream side of the exhaust gas passage; and a secondary air inlet pipe coupled to the exhaust gas passage between the upstream catalyst and the downstream catalyst, wherein a muffler is not increased in size so as to prevent an application of an excessive load to the rear of a motorcycle in order to achieve an excellent ride comfort. [Solution] The upstream catalyst is arranged in the exhaust gas passage between the power unit and the rear wheel when the motorcycle is viewed from the side. [Selected Drawings] Fig. 2

Full Text

[Document Name] Specification [Title of the Invention] EXHAUST EMISSION CONTROL SYSTEM FOR MOTORCYCLE [Technical Field] [0001] The present invention relates to an exhaust emission control system for a motorcycle, and more particularly to a catalyst provided in an exhaust gas passage. [Background Art] [0002] An exhaust emission control system has been known in which two catalysts such as an upstream catalyst and a downstream catalyst are arranged in an exhaust gas passage formed in a muffler, and a secondary air inlet pipe is provided in the exhaust gas passage (see, for example. Patent Document 1). In this structure, the muffler tends to have a large size and increased weight, because the catalysts and the secondary air inlet pipe are arranged in the muffler, and further, since the muffler arranged at the rear of the motorcycle becomes heavy, a divided load to the rear wheel increases, thereby entailing a problem that the longitudinal load should be balanced. [0003] [Patent Document 1] JP-A No. 2006-291950 [Disclosure of the Invention] [Means for Solving the Problem] [0004] The present invention aims to provide an exhaust emission control system having an excellent ride comfort by the structure in which a muffler is not increased in size so as to prevent an application of an excessive load to the rear of a motorcycle. [Problems to be Solved by the Invention] [0005] In order to solve the aforesaid problem, the invention described in Claim 1 is an exhaust emission control system for a motorcycle, including; an exhaust gas passage of an internal combustion engine in a power unit that is integrally composed of the internal combustion engine and a transmission; an upstream catalyst arranged at the upstream side of the exhaust gas passage; a downstream catalyst arranged at the downstream side of the exhaust gas passage; and a secondary air inlet pipe coupled to the exhaust gas passage between the upstream catalyst and the downstream catalyst, wherein the upstream catalyst is arranged between the power unit and a rear wheel in the exhaust gas passage when the motorcycle is viewed from the side. [0006] The invention described in Claim 2 is the exhaust emission control system of the motorcycle according to Claim 1, wherein the connection portion of rhe secondary air inlet pipe and the exhaust gas passage is arranged between the power unit and the rear wheel in the motorcycle as viewed from the side. [0007] The invention described in Claim 3 is the exhaust emission control system of the motorcycle according to Claim 1 or Claim 2, wherein a portion of the secondary air inlet pipe that extends through a wall of the muffler, which portion is in the vicinity of the connection portion between the secondary air inlet pipe and the exhaust gas passage, is formed at the inside of a muffler stay in the lateral direction of the motorcycle. [0008] The invention described in Claim 3 is the exhaust emission control system of the motorcycle according to any One of Claims 1 to 3, wherein a second secondary air inlet pipe, which is separate from the secondary air inlet pipe, is connected to the upstream side of the upstream catalyst. [0009] The invention described in Claim 5 is the exhaust emission control system of the motorcycle according to Claim 4, wherein each of the secondary air inlet pipes is an independent pipe provided with a different secondary air supply control valve. [Effect of the Invention] [0010] In the invention disclosed in Claim 1, the muffler is not increased in size in order to prevent the application Qf weight to the rear side of the motorcycle, whereby the exhaust emission control system having an excellent ride comfort can be provided. Since the upstream catalyst is arranged apart from a cylinder head of the internal combustion engine, the output of the internal combustion engine is enhanced. A space between the power unit and the rear wheel, which space is relatively free, can effectively be utilized, so that the upstream catalyst and the secondary air inlet pipe can be arranged with allowance. Since the upstream catalyst and the downstream catalyst are arranged so as to be close to each other, the exhaust gas, which is heated by the activation of the upstream catalyst, is in contact with the downstream catalyst without being cooled. Therefore, the downstream catalyst is easy to be activated. [0011] In the invention described in Claim 2, the connection portion is formed by utilizing a relatively wide space that is between the power unit and the rear wheel, whereby the degree of freedom of layout can be increased. Since the upstream catalyst and the connection portion of the secondary air inlet pipe can be made relatively close to each other, the connection portion and the downstream catalyst can be separated, with the result that a secondary air is well mixed with the exhaust gas until it reaches the downstream catalyst. Accordingly, an exhaust emission control action can be enhanced. [0012] In the invention described in Claim 3, the portion where the secondary air inlet pipe extends through a wall of the muffler, which portion is formed in the vicinity of the connection portion of the secondary air inlet pipe and the exhaust gas passage, is arranged at the inside of the muffler stay, so that the portion where the secondary air inlet pipe extends through the wall of the muffler can be hidden by the muffler stay. Therefore the appearance is improved. [0013] In the invention described in Claim 4, the second secondary air inlet pipe is provided, so that the exhaust emission control action is further enhanced. [0014] In the invention described in Claim 5, each of two secondary air inlet pipes is an independent pipe, and is provided with a different secondary air supply control valve, whereby the interference caused by the pulsation of the air in each of the secondary air inlet pipes can be avoided. Therefore, the flow rate of the secondary air can be increased to efficiently enhance the exhaust emission control performance. [Best Mode for Carrying Out the Invention] [0015] FIG. 1 is a side view of a motorcycle 1 according to an embodiment of the present invention. A body frame 2 of the motorcycle 1 includes a main frame 4, which extends rearward from a head pipe 3 mounted at the front of the body frame 2 so as to be inclined downwardly, and a pair of rignt ana iett seat rails 5 and 5 respectively extending rearward from the middle portion of the main frame 4 so as to be inclined upward to reach the trailing end. Middle frames 5 and 6 are provided between the lower end of the main frame 4 and the rear sides of the seat rails 5 and 5. [0016] A storage box or the like (not shown) is provided between the pair of right and left seat rails 5 and 5 of the body frame 2, and a seat 7 covers the storage box or the like so as to be openable and closable. A handle 8 that is j ournaled to the head pipe 3 is provided at the upper front portion of the body frame, a front fork 9 extends at the lower portion, and front wheel 10 is journaled to the lower end of the front fork 9. A pair of right and left pivot brackets 11 and 11 extends downward from a connection portion of the main frame 4 and the middle frame 6, and is fixed. A rear fork 13 extends rearward, as its leading end is journalled to the pivot brackets 11 and 11 by a pivot shaft 12. A rear wheel 14 is journaled to the trailing end of the rear fork 13. Rear cushions 15 and 15 are disposed between the rear side of the rear fork 13, which swings in the vertical direction about the pivot shaft 12, and the middle frames 6 and 6. [0017] The Dower unit 16 mounted to the motorcycle 1 is integrally composed of an internal comibustion engine 17 at its front portion and a transmission 18 at its rear portion. The internal combustion engine 17 is a single cylinder 4- cycle internal combustion engine, and includes a cylinder block 20, a cylinder head 21 and a cylinder head cover 22, those of which are superimposed with one another and project from a front surface of a crankcase 19 as greatly tilted forward to become approximately horizontal. A throttle body (not shown) is connected to an intake pipe 23 extending above the cylinder head 21. An exhaust pipe 24 extending downward of the cylinder head 21 and bent rearward extends rearward so as to be connected to a right muffler 25 of the rear wheel 14. [0018] A support bracket 26 is vertically provided at the center of the main frame 4 of the motorcycle. The power unit 16 is hung to be installed to the support bracket 26 through a support shaft 27. The rear portion of the crankcase 19 is connected to the pivot bracket 11 by the support shaft 28. By virtue of this support, the power unit 16 is fixed to the body frame 2 below the main frame 4 and in front of the pivot bracket 11. The body frame 2 is covered by a cover member 29 that is made of a synthetic resin, and is divided into the corresponding parts. [0019] In the figure, a position of a crankshaft 30 of the internal combustion engine 17 is illustrated at the front portion of the crankcase 19. Further, a position of an output shaft 31 of the power unit 16 is illustrated at the rear portion of the crankcase 19 in the figure. A power transmission chain 34 is locoed between a power transmission chain driving sprocket 32, which is fitted to the output shaft 31 of the power unit, and a power transmission chain driven sprocket 33, which is integrally formed with the rear wheel 14, whereby the rotational driving force of the power unit 16 is transmitted to the rear wheel 14. [0020] FIG. 2 is an enlarged view showing the power unit 16 and an exhaust system 37 thereof. The exhaust pipe 24 extending rearward and downward is connected to an exhaust port 38 of the cylinder head 21, and the trailing end of the exhaust pipe 24 is open into the muffler 25. The front portion of the muffler 25 is hung down from a muffler stay 39 that is jointly fastened to the pivot shaft 12 supporting the rear fork 13. The lower edge of the muffler stay 39 is welded to the muffler 25. [0021] The lower half part of the exhaust pipe 24 is provided with an upstream catalyst storing section 40 and a downstream catalyst storing section 41. The upstream catalyst storing section 40 is disposed between the power unit 16 and the rear wheel 14 when the motorcycle 1 is viewed from the side, while the downstream catalyst storing section 41 is disposed at the downstream side of the upstream catalyst storing section 40 with a space. An upstream catalyst 42 and a downstream catalyst 4 3 are filled respectively in the catalyst storing sections 4 0 and 41 disposed in an exhaust gas passage 5 3 in the exhaust pipe Z4. [0022] Two secondary air supply devices are connected to the exhaust pipe 24. A first secondary air supply device 44 is connected to the rear part of the exhaust pipe 24, i.e., connected between the upstream catalyst storing section 40 and the downstream catalyst storing section 41, while a second secondary air supply device 45 is connected to the front part of the exhaust pipe 24, i.e., connected at the position at the upstream side of the exhaust pipe 24 and close to the exhaust port 38. [0023] The fist secondary air supply device 44 includes a resonator 46, a sub-air cleaner 47, and a secondary air supply control valve 4 8, which are mounted to the lower half part of the seat rail 5 through the corresponding bracket, and a reed valve 49 mounted to the middle frame 6. The resonator 46 is connected to an air passage in the sub-air cleaner 47. The sub-air cleaner 47, the secondary air supply control valve 48, and the reed valve 49 are connected by a connection pipe 50 so as to communicate with one another. An secondary air inlet pipe 51 coupled to the reed valve 49 extends through the wall of the muffler 25 so as to be connected to a secondary air inlet pipe connection portion 52 formed at the wall of the exhaust pipe 24, which is arranged in the muffler 25, between the upstream catalyst storing section 40 and the downstream catalyst storing section 41, whereby the secondary air passing L.iij.uuyji Liiid components is supplied to an exhaust gas passage 53a between the upstream catalyst 42 and the downstream catalyst 43. The secondary air inlet pipe connection portion 52 is arranged between the power unit 16 and the rear wheel 1-^ when the motorcycle 1 is viewed from the side. A portion 54 where the secondary air inlet pipe 51 extends through the wall of the muffler, which portion is formed in the vicinity of the secondary air inlet pipe connection portion 52, is arranged at the inside of the muffler stay 39 in the lateral direction of the motorcycle. By virtue of this structure, the portion 54 where the secondary air inlet pipe 51 extends through the wall of the muffler is hidden by the muffler stay 39, whereby the appearance is improved. [0024] The second secondary air supply device 45 includes a secondary air supply control valve 55 mounted to the main frame 4 through the bracket, and a secondary air inlet pipe 56 communicating with the control valve 55. The end portion of the secondary air inlet pipe 56 at the side of the exhaust pipe 24 is coupled to a secondary air inlet pipe connection portion 57 formed at the wall of the exhaust pipe 24 below the cylinder block 20, whereby the air passing through the secondary air supply control valve 55 is supplied to an exhaust gas passage 53b between the exhaust port 38 and the upstream catalyst 42. Although not shown, a sub-air cleaner and a reed valve are integrally incorcorated into the secondary air supply control valve 55. It is to be noted that the end portion of the secondary air inlet pipe 56 may be connected to the exhaust port 38. [0025] The above-mentioned two secondary air supply devices 44 and 45 aim to send the air passing through the sub-air cleaner, the secondary air supply control valve and the reed valve to the exhaust gas passages 53a and 53b so as to burn unburned gas, whereby most of hydrocarbons and carbon monoxides are converted into harmless water and carbon dioxide. The sub-air cleaner purifies the supplied air. The secondary air supply control valve has a structure of closing a diaphragm to stop the supply of the secondary air by utilizing the negative pressure caused in the inlet pipe when the internal combustion engine is decelerated. The reed valve prevents the exhaust gas from the exhaust pipe from inversely flowing into the control valve or the sub-air cleaner. In the first secondary air supply contJrol device 44, the resonator 46 is connected to the inlet passage in the sub-air cleaner 47 in order to absorb the vibration of the supplied secondary air for reducing the intake noise. [0026] The effects described below are provided in the embodiment described above in detail. (1) The muffler 25 is not increased in size in order to prevent the application of weight to the rear side of the motorcycle, whereby the exhaust emission control system having an excellent ride comfort can be provided. Since the upstream catalyst is arranged apart from the cylinder head 21 of the internal combustion engine 17, the output of the internal combustion engine 17 is enhanced. A space between the power unit 16 and the rear wheel 14, which space is relatively free, can effectively be utilized, so that the upstream catalyst ^2 and the secondary air inlet pipe 51 or other components can be arranged with allowance. Since the upstream catalyst 4 2 and the downstream catalyst 43 are arranged so as to be close to each other, the exhaust gas, which is heated by the activation of the upstream catalyst 42, is in contact with the downstream catalyst 43 without being cooled. Therefore, the downstream catalyst 43 is easy to be activated. (2) The secondary air inlet pipe connection portion 52 is formed to the exhaust gas passage 53 by utilizing a relatively wide space that is between the power unit 16 and the rear wheel 14, "whereby the degree of freedom of layout can be increased. Since the upstream catalyst 42 and the secondary air inlet pipe connection portion 52 can be made relatively close to each other, the secondary air inlet pipe connection portion 52 and the downstream catalyst 43 can be separated, with the result that a secondary air is well mixed with the exhaust gas until it reaches the downstream catalyst 43- Accordingly, an exhaust emission control action can be enhanced. (3) The portion 54 where the secondary air inlet pipe 51 extends through the wall of the muffler, which portion is formed in the vicinity of the secondary air inlet pipe connection portion 52, is arranged at the inside of the muffler stay 39, so that the portion 54 where the secondary air inlet pipe 51 extends through the wall of the muffler can be hidden by the muffler stay 39. Therefore the appearance is improved- (4) Only the first secondary air supply device 44 of two secondary air supply devices can provide an exhaust emission control action. However, the second secondary air supply device 45 is provided, so that the exhaust emission control action is further enhanced. (5) Each of the secondary air inlet pipes 51 and 56 of two devices is an independent pipe, and they are respectively provided with the secondary air supply control valves 48 and 55, whereby the interference caused by the pulsation of the air in each of the secondary air inlet pipes can be avoided. Therefore, the flow rate of the secondary air can be increased to efficiently enhance the exhaust emission control performance. [Brief Description of the Drawings] [0027] [Fia. 1] Fig. 1 is a side view of a motorcycle 1 according to an embodiment of the present invention. [Fig. 2j Fig. 2 is an enlarged view showing a power unit 16 and an exhaust system 37 thereof in the embodiment. [Description of Reference Numerals] [0028] 14... Rear wheel 16... Power unit 17... Internal combustion engine 21... Cylinder head 24 . . . Exhaust pipe 25... Muffler 37. . . Exhaust system 38... Exhaust port 39... Muffler stay 40... Upstream catalyst storing section 41... Downstream catalyst storing section 42... Upstream catalyst 43... Downstream catalyst 44.,. First secondary air supply device 45.,, Second secondary air supply device 4 6... Resonator 47... Sub-air cleaner 48... Secondary air supply control valve 4 9... Reed valve 50... Connection pipe 51... Secondary air inlet pipe 52... Secondary air inlet pipe connection portion 53... Exhaust gas passage 53a... Exhaust gas passage between upstream catalyst 42 and downstream catalyst 43 53b... Exhaust gas passage between exhaust port 38 and upstream catalyst 42 54... Portion where secondary air inlet pipe extends through wall of muffler 55... Secondary air supply control valve 56... Secondary air inlet pipe 57... Secondary air inlet pipe connection portion [Document Name] Scope of Claims [Claim 1] An exhaust emission control system for a motorcycle, comprising: an exhaust gas passage of an internal combustion engine in a power unit that is integrally composed of the internal combustion engine and a transmission; an upstream catalyst arranged at the upstream side of the exhaust gas passage; a downstream catalyst arranged at the downstream side of the exhaust gas passage; and a secondary air inlet pipe coupled to the exhaust gas passage between the upstream catalyst and the downstream catalyst, wherein the upstream catalyst is arranged between the power unit and a rear wheel in the exhaust gas passage when the motorcycle is viewed from the side. [Claim 2] The exhaust emission control system of the motorcycle according to Claim 1, wherein the connection portion of the secondary air inlet pipe and the exhaust gas passage is arranged between the power unit and the rear wheel in the motorcycle as viewed from the side. [Claim 3] The exhaust emission control system of the motorcycle according to Claim 1 or Claim 2, wherein a portion where the secondary air inlet pipe extends through a wall of a muffler, which portion is in the vicinity of the connection portion between the secondary air inlet pipe and the exhaust gas passage, is formed at the inside of a muffler stay in the lateral direction of the motorcycle. [Claim 4] The exhaust emission control system of the motorcycle according to any one of Claims 1 to 3, wherein a second secondary air inlet pipe, which is separate from the secondary air inlet pipe, is connected to the upstream side of the upstream catalyst. [Claim 5] The exhaust emission control system of the motorcycle according to Claim A, wherein each of the secondary air inlet pipes is an independent pipe provided with a different secondary air supply control valve.

Documents:

0301--che--2009 abstract.pdf

0301--che--2009 claims.pdf

0301--che--2009 correspondence-others.pdf

0301--che--2009 description (complete).pdf

0301--che--2009 drawings.pdf

0301--che--2009 form-1.pdf

0301--che--2009 form-18.pdf

0301--che--2009 form-26.pdf

0301--che--2009 form-3.pdf

0301--che--2009 form-5.pdf

0301--che--2009 others.pdf

301-CHE-2009 AMENDED CLAIMS 30-09-2014.pdf

301-CHE-2009 FORM-1 30-09-2014.pdf

301-CHE-2009 FORM-3 30-09-2014.pdf

301-CHE-2009 AMENDED PAGES OF SPECIFICATION 30-09-2014.pdf

301-CHE-2009 EXAMINATION REPORT REPLY RECIEVED 30-09-2014.pdf

301-CHE-2009 - Petiton 137 - POR.pdf

301-CHE-2009 CORRESPONDENCE OTHERS 24-10-2014.pdf

301-che-2009 form-3 10-08-2009.pdf