SECONDARY AIR INTAKE SYSTEM FOR A SADDLE TYPE VEHICLE

FIELD OF THE INVENTION

[0001] The present subject matter relates generally to a secondary air intake system, and more particularly, to the intake of air in a secondary air intake system for a saddle type vehicle with a swinging power unit.

BACKGROUND OF THE INVENTION

[0002] Generally, a secondary air intake system is disposed on a vehicle frame above a swinging power unit with the help of a bracket along with a separate air filter and it is co-fastened along with the air filter. The secondary air intake system is connected to a cylinder head assembly through a conduit and provides fresh air (or secondary air) into the conduit to allow fuller combustion of exhaust gases. In a saddle type vehicle, the entire system is positioned underneath a side panel of the vehicle and hence concealed from an onlooker. Through the oxidation of outgoing exhaust gases, the emission of harmful exhaust gases containing carbon monoxide and urburnt hydrocarbons into the environment can be reduced, more particularly during cold start conditions.

[0003] Previously, the effectiveness of this system depended on the method of injection and the point at which the secondary air enters the exhaust system. But with the advancement of emission control strategies and introduction of catalytic converters, the function of secondary air intake system has shifted from a typical primary emission control device to a device which also supports the efficient function of the catalytic converter.

[0004] The air intake by the secondary air intake system is routed through a conduit open on one side. This air is fed into the air filter which filters the air and the filtered air is fed into the cylinder head assembly of the engine. The Japanese patent application No. 02-218067 explains another attempt to supply the air into the said air filter through a cooling fan used for forced air cooling of the cylinder head of a swinging power unit. The cooling fan is generally centrifugal and a part of the air which has cooled the cylinder head within a cooling cowl is put into the secondary air intake port.

[0005] However, this construction uses the cooling fan primarily used to cool the engine and makes the intake of secondary air dependent on the outgoing air from the cooling cowl. It is worth mentioning that the cooling fan itself is dependent on the crankshaft. The forced air increases the efficiency of the secondary air intake system but with a cost impact. This construction though being efficient increases the cost of the complete secondary air intake system due to involvement of the cooling fan and at the same time also creates layout problem due to limited available space in the vehicle to accommodate the engine and other functioning units. Further, the outgoing air which has been in contact with the cylinder head is very hot and may not be feasible as secondary air. Furthermore, the construction also leads to pressure drop at the air outlet in the cooling cowl as the secondary air intake port opens within the cylinder head cooling cowl. The pressure drop may reduce cooling efficiency which may lead to undesirable ramifications as engine cylinder head is a critical component.

[0006] Hence, the present subject matter is directed to overcome all or any of the problems as set forth above and obviate the lacunae in the prior art. There is a possible a construction which allows the secondary air to be routed in through other locations rather than the critical cooling cowl for the engine. It is therefore an object of the present invention to disclose a secondary air intake system for an internal combustion engine with a continuously variable transmission unit where the air intake for the secondary air intake system is facilitated through the continuously variable transmission unit. Another object of the present invention is that of providing a secondary air intake system, which is inexpensive to make and simple to assemble. It is yet another object of the present invention to provide a secondary air intake conduit for a secondary air system for reducing pollution to the environment where the secondary air intake conduit is connected to the continously variable transmission unit.

SUMMARY OF THE INVENTION

[0007] To this end, the present invention discloses a secondary air intake system for a saddle type vehicle wherein the secondary air intake system is assisted for secondary air intake by a cooling system of a continuously variable transmission unit comprising an inlet, an outlet and plurality of fan blades mounted on one of the pulleys therein, and wherein the secondary air to the secondary air intake system is facilitated through the outlet of the continuously variable transmission unit.

[0008] According to an aspect of the present invention, a secondary air intake conduit connects the secondary air intake system to the outlet of the continuously variable transmission unit. Additionally, the secondary air intake system comprises a secondary air injection valve, a reed valve and an air filter such that the incoming secondary air enters from the outlet of the continuously variable transmission unit into the secondary air intake conduit from where it is directed towards the air filter. The secondary air is filtered by the said air filter and delivered to the said secondary air injection valve.

[0009] According to a further aspect of the present invention, the secondary air intake system further comprises a cylinder head inlet tube extending from the reed valve to an exhaust port in a cylinder head of the engine for delivering secondary air to the said exhaust port.

[00010] The foregoing objectives and summary provide only a brief introduction to the present subject matter. To fully appreciate these and other objects of the present subject matter as well as the subject matter itself, all of which will become apparent to those skilled in the art, the ensuing detailed description of the subject matter and the claims should be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[00011] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description, appended claims and accompanying drawings where:

FIG. 1 shows a typical saddle type vehicle with a swinging power unit.

FIG. 2 shows a left side view of the secondary air intake system according to the present invention.

FIG. 3 illustrates a perspective view of the present invention.

FIG. 4 depicts the front view of the secondary air intake system according to the present invention.

FIG. 5 depicts a right side view of the present invention.

FIG. 6 shows the secondary air intake system mounted on the saddle type vehicle.

DETAILED DESCRIPTION OF THE INVENTION

[00012] The subject matter described herein relates to the secondary air intake system in a saddle type vehicle. The invention provides a low cost standalone mechanism for achieving high flow rate based secondary air injection which uses air from the variable cooling air system of a saddle type vehicle. In the ensuing exemplary embodiments, the vehicle is a saddle type vehicle with a swinging power unit. However it is imperative that the concepts of the present invention may be applied to other types of vehicles within the spirit and scope of this invention such as a scooter, motorcycle or moped.

[00013] Further "front" and "rear", and "left" and "right" wherever referred to in the ensuing description, refer to front and rear, and left and right directions as seen in a state of being seated on a seat of the saddle type vehicle. Furthermore, a longitudinal axis refers to a front to rear axis relative to the vehicle, while a lateral axis refers generally to a side to side, or left to right axis relative to the vehicle. Various other features and embodiments of the secondary air intake system according to the present subject matter here will be discernible from the following further description thereof, set out hereunder.

[00014] FIG. 1 illustrates the side view of a concerned saddle ride type vehicle with a swinging power unit. Typically such a vehicle includes a body frame assembly made up of several tubes welded together which usually supports the body of the said vehicle. The vehicle has a steerable front wheel 110 and a driven rear wheel 111 driven by driving force generated by an engine 102. The frame assembly 101 of the saddle ride type vehicle with the swinging power unit is an elongated structure, which typically extends from a forward end to a rearward end of the vehicle. It is generally convex in shape, as viewed from a side elevational view. The said frame assembly 101 includes a main frame and may also have a sub-frame. The sub-frame is attached to the main frame using appropriate joining mechanism. The frame assembly 101 includes a head tube (not shown) and a down tube that extends downward from head tube. The frame assembly is covered by a plurality of vehicle body covers including a front panel 115, a leg shield 116, an under seat cover 117 and a side panel 112.

[00015] A handlebar assembly 105 and a seat assembly 106 are supported at opposing ends of the frame assembly and a generally open area is defined there between known as floorboard 107 which functions as a step through space. The seat for a driver and a pillion is placed forward to the fuel tank (not shown) and rearwardly of the floorboard 107. A fuel tank that stores fuel that is supplied to the engine is disposed at the rear end of the vehicle above the rear wheel. It is present on the upper side of the power unit along with a fuel tank cap. A side stand provided to the rear of the engine and fixed to the left side of the body frame supports the vehicle such that vehicle inclines to the left side.

[00016] A front fender 113 is provided above the front wheel 110 to avoid the said vehicle and its occupants from being splashed with mud. Likewise a rear fender 109 is placed between fuel tank and rear wheel 111, and to the outer side in the radial direction of rear wheel. Rear fender 109 inhibits rain water or the like from being thrown up by rear wheel 111.

[00017] Typically, front 103 and rear 114 suspension assemblies are operatively positioned between the front 110 and rear 111 wheels and the frame assembly. The front suspension assembly 103 commonly is a telescopic fork arrangement while the rear suspension assembly 114 is a hydraulic damped arrangement.

[00018] In the said vehicle, the rear suspension swing arm typically supports a power unit which is configured to drive the rear wheel 111 of the vehicle. The power unit is structured such that an engine 102 and a swing case 108, which are well known for this form of saddle type vehicle, are integrally constructed. For example, the engine is a four stroke single cylinder engine and a swing case is connected to a left side surface of a crankcase of the engine so as to extend forward.

[00019] It is disposed on the vehicle frame with one end of the swing case 108 attached to the rear wheel hub in such a way that the power unit is substantially angularly disposed to the ground. The engine 102 is arranged horizontally, that is, its crankshaft is placed at right angles to the longitudinal direction of the vehicle body. The said power unit is surrounded by a shroud (not shown) or a covering with a fan to enhance forced cooling of the power unit. This covering present over the power unit is known as cooling cowl and may be made of plastic resin or the likes. A continuously variable transmission has a transmission case assembled in the swing case 108. The rear portion of the vehicle is generally covered on both sides by side panels 112. They improve the aesthetic look of the vehicle. A muffler is provided to the right side of the rear wheel, and connects to the engine. The exhaust gases entering the muffler from the engine are further oxidized by the secondary air injected through the secondary air intake system to reduce harmful pollutants. The secondary air intake system, indicated generally by the reference numeral 200, is not visible to an onlooker as it is positioned in the space between the side panels 112.

[00020] The concept of a typical secondary air intake system is now briefly described for lucid understanding. The secondary air intake system is a mechanism to control the emissions produced from a vehicle by injecting additional air near to the exhaust port. Usually the exhaust gases contain large quantities of unburnt gases including carbon monoxide and other hydrocarbons. If the secondary air abundant in oxygen is added at a place close enough to the exhaust port and where exhaust gases still have a high temperature, the added air can complete the combustion of any unburned hydrocarbons by oxidising them (known as afterburning) and also convert carbon monoxide into carbon dioxide.

Thus the addition of a supply of secondary air to the exhaust system can be helpful in reducing the emissions of unwanted gas constituents.

[00021] The secondary air intake system usually consists of a reed valve, an air-cut valve, an air filter and conduits for connecting the said valves to other elements. The reed valve is a one way check valve which is opened by a negative pressure of a pressure wave of the exhaust gas. It permits the air to flow into the exhaust system but does not permit the exhaust gases to escape into the atmosphere. The air-cut valve restricts the flow of the secondary air so as to prevent excessive air from entering into the exhaust gas passage such as under power unit idle or high load, high speed conditions. The system draws air from clean side of the air filter.

[00022] The secondary air intake system according to the present invention is now described according to the FIGS 2-6. The secondary air intake system in the present invention consists of a secondary air injection valve 201 and an air filter 202 both of which are mounted on the rear body frame of the vehicle with the help of a holder or bracket. According to a preferred embodiment, the air filter 202 is a cylindrical foam filter. In the secondary air intake system according to an embodiment thereof, the air intake is routed through the outlet 211 of the continously variable transmission unit by a secondary air intake conduit 203, unlike the prior art where it was generally routed through the air filter from the environment. The secondary air intake conduit 203 is a cylindrical tube like structure made of plastic resin or sheet metal and connects the secondary air intake system to the continously variable transmission unit.

[00023] The belt driven continously variable transmission has a primary pulley 206 provided on an input shaft 207 (connected to the engine), and a secondary pulley 209 provided on an output shaft 212. A drive belt 208 connects both the pulleys. By changing the contact diameter of the drive belt, the rotation speed transmitted from the input shaft 207 to the output shaft 212 is changed continously and helps maintain variable gear ratios. The continously variable transmission unit has fan blades 213 on the primary pulley extending radially outwards. These fan blades 213 suck the cooling air from the inlet 210 into the continously variable tranmsision case which cool the belt, pulley and clutch of the said transmission system. The now warm air leaves the said system from the outlet 211. The warm air is redirected by the secondary air intake conduit 203 to the air filter 202. The secondary air injection valve 201 injects this filtered air into the cyliner head exhaust port via a cylinder head inlet tube 205. The flow of air from the transmission unit to the air filter and subsequently to the cylinder head 204 is shown in FIG. 3 by arrows. The addition of secondary air to the exhaust system is helpful in reducing the emissions of unwanted gas constituents. When the exhaust pressure is higher than the atmospheric pressure, the reed valve in the secondary air intake system closes and reverse flow of the exhaust air is precluded. FIG. 6 shows the secondary air intake system mounted on the saddle type vehicle.

[00024] The present subject matter and its equivalent thereof offer many advantages, including those which have been described henceforth. The present invention ensures sufficient supply of secondary air for exhaust gas purification.

The flow rate of air decides the conversion efficiency of the secondary air injection and the catalytic converter system. Due to space and cost constraints, the use of a separate fan to increase the flow rate is not possible in two wheeled saddle type vehicles. This constraint is overcome by using the fan blades of the continuously variable transmission unit. The arrangement helps the secondary air intake system to get the secondary air at higher temperature and at higher pressure which is desirable for better efficiency. This air is at a lower temperature than the air procured from the cooling cowl in the prior art which is at a much higher temperature. Thus, the present invention increases the efficiency of the secondary air intake system without any significant cost impact. Moreover the present system does not use the cooling centrifugal fan, usually mounted on the crankshaft for forced cooling, for secondary air intake which makes it a standalone system without being dependent on the cooling fan. Hence, the present invention is optimized to work in the vehicles not having the said centrifugal cooling fan.

[00025] Even if the engine is equipped with a centrifugal cooling fan, the secondary air can be obtained through the fan blades of the continuously variable transmission unit 108 by the secondary air intake conduit. Thus the use of the present invention is restricted to the engine having a continuously variable transmission unit.

[00026] The present subject matter is thus described. The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore the forgoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the appended claims.

We claim:

1. A secondary air intake system for a saddle type vehicle, the said secondary air intake system assisted for the secondary air intake by a cooling system of a continuously variable transmission unit comprising an inlet, an outlet and plurality of fan blades mounted on one of the pulleys therein, and wherein the secondary air to the secondary air intake system is facilitated through the outlet of the continuously variable transmission unit.

2. The secondary air intake system as claimed in claim 1, wherein the said continuously variable transmission unit is connected to an internal combustion engine.

3. The secondary air intake system as claimed in claim 1, wherein a secondary air intake conduit connects the secondary air intake system to the outlet of the continuously variable transmission unit.

4. The secondary air intake system as claimed in claim 1 or claim 3, wherein the secondary air intake system comprises a secondary air injection valve, a reed valve and an air filter such that the incoming secondary air enters from the outlet of the continuously variable transmission unit into the secondary air intake conduit from where it is directed towards the air filter, the secondary air filtered by the said air filter and delivered to the said secondary air injection valve.

5. The secondary air intake system as claimed in claim 1 or claim 4, wherein the said system further comprises a cylinder head inlet tube extending from the reed valve to an exhaust port in a cylinder head of the engine for delivering secondary air to the said exhaust port.

6. The secondary air intake system as claimed in claim 1 or claim 3 or claim 4, wherein the said secondary air intake conduit is made of any material including a plastic resin or sheet metal.

7. A secondary air intake system substantially as herein described and illustrated with reference to the accompanying drawings.