Abstract:
An exhaust gas recirculation device for reducing nitrogen oxide in exhausting gas of a motorcycle engine includes an exhaust gas recirculation pipe between an exhausting end and a negative pressure air inlet end of the engine; at least one check valve installed in the exhaust recirculation pipe. A negative pressure control valve is installed between the check valve and the inlet end of the engine. Thereby the negative pressure of the engine is used as a power source so as to guide unidirectionally exhaust gas containing carbon dioxide at the exhausting end to the inlet end of the engine through the check valve and the negative pressure control valve so as to decrease operation temperatures of the engine and as a result, nitrogen oxide in the exhaust gas of the engine is reduced.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to exhaust gas recirculation devices for reducing the nitrogen oxide from the motorcycle engine, and particularly to an exhaust gas recirculation device which can introduce the exhaust gas from the engine into the air inlet end of the engine. Since the exhausting gas contains a large amount of carbon dioxide so as to reduce the operation temperature of the engine. Thereby it is difficult to generate nitrogen oxide in the exhaust gas of the engine.  
       BACKGROUND OF THE INVENTION  
       [0002]     Conventionally, catalytic converter is installed in the exhausting pipe of the engine for reducing the nitrogen oxide in the exhaust gas. The catalytic converter with precious metal rhodium (Rh) can reduce the harmful nitrogen oxide in the exhaust gas to harmless nitrogen (N 2 ) and oxygen (O 2 ).  
         [0003]     Moreover, platinum (Pt) and palladium (Pd) are also contained in the catalytic converter for oxidizing the carbon monoxide (CO) and hydro- carbon (HC) into harmless carbon dioxide and water. However in the oxidation of CO and HC, the increment of temperature of the exhaust gas will decrease the nitrogen oxide reduction efficiency of rhodium. Especially, the secondary air is generally introduced into exhausting pipe installed at least one catalytic converter having platinum, palladium and rhodium. The prior art only increases the purifying of the CO and HC, but not beneficial to the purifying of NOx. As a result, more nitrogen oxide is exhausted so as to induce acid rain or to destroy the ozone layer in the atmosphere.  
         [0004]     Furthermore, the NOx containing NO, NO 2  and N 2 O are generated when the spark plug is exploded, especially in an environment with nitrogen (N 2 ) and oxygen (O 2 ). If the ignition of the spark plug is fired to explode the fuse, the temperature of the engine can be reduced properly under consideration of the efficiency of the operation of the engine. Then the combination efficiency of the nitrogen and oxygen as the spark plug ignites the fuse will be reduced. However no prior art has this effect. Thus, the harmful nitrogen oxide as the engine operates is still a problem to be overcome.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is to provide an exhaust gas recirculation device for reducing nitrogen oxide in exhausting gas of a motorcycle engine, wherein part of exhaust gas from the exhausting end of the engine is guided into the air inlet end so that the negative pressure of the engine to is provided to the mixer of air and fuel so as to have a predetermined air to fuel ratio. Then the mixer is supplied to the cylinder of the engine. Since the exhaust gas has a large amount of carbon dioxide, the carbon dioxide in the mixer having the predetermined air to fuel ratio is increased. Thereby the operation of the engine is reduced so as to prevent the ignition of the spark plug from generating harmful nitrogen oxide (NOx).  
         [0006]     Another, the present invention is to provide an exhaust gas recirculation device, wherein the use of expensive rhodium is reduced in the catalytic converter since the carbon dioxide is added to the mixer of air and fuel so as to reduce the operation temperature.  
         [0007]     Further, the present invention is to provide an exhaust gas recirculation device which can be used to the air inlet system of a conventional motorcycle engine with a carburetor or with an electronic fuel injection system and the nitrogen oxide in the exhaust gas of the engine is sufficiently reduced.  
         [0008]     Accordingly, the present invention provides an exhaust gas recirculation device for reducing nitrogen oxide in exhausting gas of a motorcycle engine. The device comprises an exhaust gas recirculation pipe between an exhausting end and a negative pressure air inlet end of the engine. The exhausting end is a branch tube at a front section of an exhausting tube of the engine. The front section is positioned at an exhausting tube between the exhausting opening and a position assembled the catalytic converter.  
         [0009]     The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a system block diagram, where it is illustrated that an exhaust gas recirculation path is formed between the exhausting end and the air inlet end of a motorcycle engine and a check valve and a negative pressure control valve are installed in the exhaust gas recirculation pipe.  
         [0011]      FIG. 2  shows the arrangement of the exhausting end of the present invention, wherein a branch tube is installed at a front section of the exhausting tube of an engine, which is further connected to the exhaust gas recirculation pipe.  
         [0012]      FIG. 3  is a cross sectional view of another exhausting end of the present invention, where the branch tube on the exhausting channel of the engine cylinder as an exhausting end.  
         [0013]      FIG. 4  shows a block diagram of the air inlet end of the present invention, wherein a flow adjustor is installed to a carburetor (or an electronic fuel injection system).  
         [0014]      FIG. 5  is a cross sectional view showing the flow adjustor of the present invention, where a flow adjustor with a neck-like hole is installed at the air inlet end and is connected between the air inlet channel and the exhaust gas recirculation pipe.  
         [0015]      FIG. 6  is a cross sectional view showing the check valve of the present invention, wherein the unidirectional valve gate and a stopper for confining the opening of the valve gate are installed in the valve.  
         [0016]      FIG. 7  is a cross sectional view showing the arrangement between the throttle valve and the negative pressure control valve, wherein it is illustrated that negative pressure control valve has a tube which is connected to the air inlet end of the throttle valve for opening and closing the exhaust gas recirculation pipe by the negative pressure. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     In order that those skilled in the art can further understand the present invention, a description will be described in the following in details. However, these descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims.  
         [0018]     With reference to  FIG. 1 , the exhaust gas recirculation device of the present invention is illustrated. It is illustrated that the exhaust gas recirculation device is installed on a conventional carburetor  14 . The components of the present invention will be described herein.  
         [0019]     In an exhausting end of an motorcycle engine  1 , referring to  FIG. 1 , a branch tube  23  (see  FIG. 2 ) is installed at a front section  21  of an engine exhausting tube  20  which is then connected to an exhaust gas recirculation pipe  4  for collecting part of exhausting gas. The front section  21  is positioned in an exhausting pipe  22  from the exhausting opening  10  of the engine  1  to the position assembling a catalytic converter  11 . Furthermore, in the embodiment, the exhausting end  2  may be connected to the branch tube  24 , see  FIG. 3 , on an exhausting channel  13  capable of being connected the exhaust gas recirculation pipe  4  for collecting part of exhausting gas.  
         [0020]     A motorcycle air inlet end  3  is included, see  FIG. 3 . For a motorcycle engine  1  with a carburetor  14 , the air inlet end  3  is positioned in air inlet channel  30  between the carburetor  14  and the air inlet branch tube  15  of the engine, see  FIG. 1 . A flow adjustor  16  can be installed at the air inlet end  3 , as shown in  FIG. 4 . In the embodiment, the flow adjustor  16  may be made as a flow channel with a neck-like hole  16 , see  FIG. 5 . One end thereof is inserted into the air inlet channel  30  and another thereof is connected to the exhaust gas recirculation pipe  4 . The flow rate of the carbon dioxide flowing into the air inlet channel  30  from the exhaust gas recirculation pipe  4  can be controlled by the size of the neck-like hole  161 .  
         [0021]     The exhaust gas recirculation pipe  4  has a soft tube, thereby, the exhaust gas recirculation pipe  4  being connected between the exhausting end  2  and the air inlet end  3  of the engine  1 , see  FIG. 1 . A check valve  5  is installed adjacent the exhaust gas recirculation pipe  4  of the exhausting end  2 . A negative pressure control valve  6  is installed on the exhaust gas recirculation pipe  4  between the check valve  5  and the air inlet end  3  of the engine  1 . The check valve  5  has a reed  51  for opening or closing the valve at one side of a valve due to action of airflow and a stop plate  52  (referring to  FIG. 6 ) for confining the opening of the valve and for avoiding the elastic fatigue of the reed  51 . The reed  51  of the check valve  5  is opened unidirectionally in the exhaust gas recirculation pipe  4  along a direction from the exhausting end  2  to the air inlet end  3 . In other words, by the control of the check valve  5 , the exhausting gas at the exhausting end  2  can be guided to the air inlet end  3  unidirectionally. The exhausting gas cannot flow from the air inlet end  3  to the exhausting end  2  so as to prevent fuel from draining out.  
         [0022]     The negative pressure control valve  6  has two end tubes  61 ,  62  which are connected to the exhaust gas recirculation pipe  4 , see  FIG. 7 . Moreover, the negative pressure control valve  6  has a negative pressure tube  63  which is connected to a negative pressure soft tube  60  so as to be further connected to an air inlet of a throttle valve  141 . The end tubes  61 ,  62  are formed with valves  64 ,  65 . The closing and opening of the valves  64 ,  65  are controlled by a soft valve gate  66 . A press reed  67  is installed on the valve gate  66 . Referring to  FIG. 7 , it is illustrated that the exhausting end connected to the carburetor  14  is further connected with the air inlet channel  30  for supplying fuel. The air inlet end  3  is connected to the air inlet tube  30 .  
         [0023]     The check valve  5  and the negative pressure control valve  6  may be integrally formed and are assembled to the exhaust gas recirculation pipe  4 .  
         [0024]     By above mentioned structure, when an engine  1  with the conventional carburetor  14  is actuated, the valve opening of the throttle valve  141  of the carburetor  14  is controlled by the fuel flow, see  FIG. 7  so as to adjust the mixing ratio of fuel and air to be supplied to the engine  1 . Meanwhile, an air inlet end of the throttle valve  141  in the carburetor  14  (or electronic fuel injection system) has negative pressure. The negative pressure dynamic power is captured through the negative pressure soft tube. The pressure is transferred by the negative pressure tube  63  to such the valve gate  66  to open the valve. Thus, the valve  64  and valve  65  are communicated to one another so as to open the path in the exhaust gas recirculation pipe  4  between the air inlet end  3  and exhausting end  2 . Then, the negative pressure in the air inlet channel  30  will guide part of exhausting gas to flow through the exhaust gas recirculation pipe  4  to actuate the check valve  5  to open the valve unidirectionally. Thereby the circulation exhausting gas is guided to the air inlet end  3  of the engine  1  so as to induce the check valve  5  to open unidirectionally. Thereby the circulation exhausting gas can be guided to the air inlet end  3  of the engine  1  and then is guided to the air inlet channel  30  to mix with fuel to has a predetermined air to fuel ratio. Then the mixer is supplied to the cylinder of the engine. Since a large amount of carbon dioxide is in the exhausting gas, the content of the carbon dioxide in the mixer of fuel and air is increased to reduce the operation temperature of the engine. Thereby the harmful nitrogen oxide (Nox) generated as the spark plug is reduced. Thus, the exhausting amount of NOx from the motorcycle engine  1  with the carburetor  14  is reduced.  
         [0025]     In the embodiment of the present invention, the returned exhausting gas from the exhausting end  2  of the engine  1  is based on the moving frequency of the negative pressure suction force in the air inlet channel  30 . The relation of returned exhausting gas, fuel supplies in high and low rotation speeds and exhausting gas amount of the engine is a geometric series. The higher the rotation speed of the engine, the more the returned exhausting gas flowing into the cylinder of the engine. The high temperature in high operation speed can be reduced by the carbon dioxide in the exhausting gas so that in ignition, it is difficult to generate NOx so as to reduce the contents of NOx in the exhausting gas to enhance the equality of exhausting gas. Moreover, the rhodium (Rh) in the reduced type catalyst in the exhausting tube can be reduced.  
         [0026]     Furthermore, it is allowable in the present invention that no negative pressure control valve  6  is installed in the exhaust gas recirculation pipe  4 . Only the negative pressure in the air inlet channel  30  serves to suck the recirculated exhausting gas in the exhausting end  2 . Therefore, although no negative pressure control valve  6  is used to control the opening timing of the exhaust gas recirculation pipe  4 , the check valve  5  can be used to prevent the fuel to drain to the exhausting end  2 . However all these are within the scope of the present invention.  
         [0027]     Besides, the exhaust gas recirculation device of the present invention can be used to a motorcycle engine with electronic fuel injection system. The difference of this embodiment from above mentioned embodiment having engine with a carburetor is that the carburetor  14  is replaced by an electronic fuel injection system. Other components are identical to the previous system. The negative pressure in the air inlet channel  30  serves to suck part of exhausting gas which then flows into the cylinder of the engine. The carbon dioxide in the exhausting gas serves to reduce the operation temperature of the engine. Thereby the exhausting NOx in the engine with electronic fuel injection system is reduced.  
         [0028]     The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.