DESC:FIELD OF INVENTION

The invention relates generally to a secondary air injection system for an internal combustion engine. More particularly, the invention relate to arrangement and positioning of a secondary air injection device of the secondary air injection system in saddle type vehicles.

BACKGROUND

Over the past century, pollution has grown enormously which has led to problem of global warming. Automobile emissions are one of the pollutants. Automobile emissions contain hydrocarbon (HC) and carbon monoxide (CO). To keep the pollution under check, it is essential to reduce level of hydrocarbon (HC) and carbon monoxide (CO) in the exhaust gas of the automobiles.

Various ways are adopted to reduce the amount of pollutants in the exhaust gas for e.g. catalytic reduction. One such method of reducing to reduce concentrations of HC and CO in exhaust gas from an internal combustion engine, is to provide an exhaust gas purifier of the type that oxidizes exhaust gases using secondary air provided through a secondary air injection system. The secondary air injection system includes a secondary air control device which controls the flow of a secondary air into the exhaust gas. The secondary air supply may be provided to through an air cleaner using an air pump or air injection can also be controlled by taking input from the negative pressure pulses in the intake manifold. The secondary air injection system also helps in keeping tailpipe emission under control under various altitudes.

In case of saddle type vehicle, use of a secondary air injection system using secondary air injection is common to reduce the pollutant level in exhaust gas. Usually a saddle type vehicle includes a frame on which various vehicle components such as engine, fuel tank, air cleaner, etc. are mounted. Accommodating various additional components of secondary air injection system such as secondary air control device, associated tubing, etc. is challenging as limited space is available within a frame structure of saddle type of vehicle.

One of the common frame structure that is being used in the saddle type vehicle is a double cradle frame. Double cradle frame include a head pipe, a rearward extending main spine, a seat frame extending rearward from main spine and a pair of rearward extending down tubes from the head pipe. These type of frames offer rigidity, strength and better handling.

In a saddle type of vehicle with a double cradles type of frame, space formed within the double cradles and main spine accommodates an engine, a transmission and their associated components such as an air cleaner, an air intake system, a carburetor, etc. In such vehicles, mounting of the additional components such as air purifying system with a secondary air control device is difficult due to space constraint. Positioning of the secondary air control device in this space may lead to compromising and re-positioning of the components in current layout. Further, to achieve desired noise, vibration, and harshness (NVH) performance, it is desirable that the secondary air injection device is mounted on the frame.

One of the probable location for mounting of secondary air injection device could be on the rear side of the frame. However, such mounting arrangement will lead to increase in length of tubing associated with secondary air control device. This increase is material required and cost involved. Further, this will also increase complexity of layout. As the length of the tubing increases, the pressure drop also increase which may affect the performance of the secondary air control device. When the secondary air control device is mounted on the rear side of the frame, it may remain exposed to hot air coming from engine. This can further affect the performance of the secondary air control device negatively.

Other probable location for mounting of the secondary air control device could be on main spine under the fuel tank. However, this position may not be available always as some other larger size vehicle components such as anti-lock braking system (ABS) may be mounted there. Further, at this position the secondary air control device and its tubing lie directly above the engine and may get affected due to engine heat.

Mounting of the secondary air control device at any other location on the frame may disturb the layout of other components of the vehicle. It may also cause obstruction during assembly of other vehicle components and accessing of the vehicle components during their repair and maintenance. Further, the conventional mounting arrangement and position of the secondary air control device does not allow formation of secondary air control device and its mounting arrangement as a separate subassembly. This lead to increase in time and effort in assembly of the secondary air control device on the main assembly line.

As an alternate solution, the secondary air control device may be mounted on the one of the cradles of the frame in the front. However, when the secondary air control device is mounted on only single down tube, there remains a substantial overhang. This may affect the NVH performance negatively. Further, due to overhang, chances of failure of attachment structure of the secondary air control device for e.g. bracket increase to great extent. When the secondary air control device is mounted on a single down tube, it is difficult to get the desired orientation of the secondary air control device so that tubing arrangement can be made conveniently.

In light of foregoing discussion, there is a need to provide an improved secondary air injection system for saddle type vehicle which can overcome the limitations stated above.

OBJECTIVES OF THE INVENTION

It is an object of the present invention is to provide a secondary air injection system with a secondary air control device which can be mounted at an appropriate location and attached to the frame firmly to prevent NVH issues.

Yet another object of the present invention is to provide an improved secondary air injection system wherein the secondary air control device is protected from the engine heat and has optimum tubing length.

Yet another object of the present invention is to provide a secondary air injection system with a secondary air control device which is easy to assemble, easy to service and cost effective.

Yet another object of the present invention is to provide a secondary air injection system with a secondary air control device which does not affect position of other components and does not affect assembly and maintenance of other components such as engine.

Yet another object of the present invention is to provide a secondary air injection system with a secondary air control device wherein position of the secondary air control device does not affect the ram air coming to the engine for cooling of the engine.

Yet another object of the present invention is to provide a secondary air injection system with a secondary air control device wherein the secondary air control device along with its mounting arrangement such as bracket can be formed as subassembly to reduce assembly time and effort.

Yet another object of the present invention is to provide a secondary air injection system with a secondary air control device which is protected from exposure to dust, dirt and water.

Yet another object of the present invention is to provide a secondary air injection system which does not affect the vehicle aesthetics.

SUMMARY OF THE INVENTION

With such objects in view, the present invention provides a saddle type vehicle comprising
a frame having a head pipe, a main spine extending rearward from the head pipe and a plurality of downward and rearward extending down tubes;
an engine positioned within the space formed between the main spine and the plurality of down tubes; and
a secondary air injection system comprising a secondary air control device to control supply of a secondary air within a secondary air supply path;
wherein the secondary air control device is supported on at least two down tubes of the frame.
Preferably,
- the secondary air control device is at least partially ahead of an engine cylinder
- the secondary air control device is at least partially behind the down tubes and at least partially under the main spine
- the secondary air control device is at least partially under the headlight

The frame used in the saddle type vehicle is a double cradle type frame.

A suitable mounting arrangement for e.g. bracket may be provided to mount the secondary air control device on the down tubes of the frame. The mounting arrangement such as bracket is attached to the down tubes of the frame directly by welded joint or through bolted arrangement or any other suitable joining method/means. The secondary air control device is attached to the mounting bracket using suitable attaching means such as bolt, adhesive, etc. In another aspect of invention, the secondary air control device and the mounting bracket may be formed as integral assembly.

Orientation of the mounting bracket is suitably kept to achieve desired orientation of the secondary air control device so as allow easier routing of associated tubing. As the mounting bracket takes the support from multiple down tubes, the secondary air control device attached to the bracket does not have any overhang. This ensures a stiffer mounting of the secondary air control device on the frame which is less susceptible to mechanical failures. This also improves overall NVH performance of the assembly.

While packaging of the secondary air control device on down tubes of the frame with the help of the mounting bracket, design of span between down tubes, design of the mounting bracket and design of tube routing from the secondary air control device is kept such that, packaging of the secondary air control device does not affect assembly and maintenance engine and other vehicle components for e.g. while engine maintenance if tappet cover is to be removed, packaging of the secondary air control device does not pose incontinence due to appropriate designing of span between down tubes of frame, mounting bracket and tube routing,

Preferably, the location and orientation of secondary air control device is such that it does not affect the flow of the ram air coming to the engine. Further, the span between the down tubes of the frame is designed such that secondary air control device can be accommodated without affecting ram air and vehicle aesthetics. Thus, the engine cooling and the vehicle aesthetics are not affected due to position of the secondary air control device.

While packaging of the secondary air control device on down tubes of the frame, limited space is available for packaging of the associating routing tubes. The bends of the routing tubes are designed such that they do not foul with the other vehicle components or cause inconvenience during assembly and maintenance of the vehicle components. Further, as the routing tubes from the secondary air control device goes towards rear side of the vehicle for connecting to engine and air cleaner, they have to pass through high heat region. In order to protect routing tubes from high heat, routing tubes are passed along the main spine of the frame and supported by main spine to keep them out of hot zone. This arrangement also keeps routing tubes concealed and vehicle aesthetics is preserved. Further, routing tube connection with the air cleaner is designed such that it won’t foul with fuel tank and get damaged. To avoid damage to the routing tube due to rubbing with fuel tank edge, the fuel tank edge can be provided with rubber beading.

In the proposed invention, the secondary air control device and the mounting bracket may be formed as a separate subassembly and mounted on the frame directly. This may help to reduce assembly time. Further, the proposed position of the secondary air control device is easily accessible which allows easy repair and maintenance.

Arrangement of the secondary air control device according to proposed invention is not visible directly as the secondary air control device is positioned remains behind the front wheel mudguard. Due to which there is no effect on vehicle aesthetics. Further, as the secondary air control device remain within the frame structure and behind the front wheel guard, it remains protected from external adverse weather conditions such as dust, debris, dirt, water, etc. This also prevents any direct mechanical impact on the secondary air control device.

Arrangement proposed as per invention does not obstruct positioning of any other vehicle components such as engine, air cleaner, carburetor, etc. Further, position of the secondary air control device does not affect the access to engine. This helps in easy assembly and maintenance of engine.

In one of the embodiments of the invention, the secondary air injection system may take clean air to be injected in an exhaust gas through the exhaust gas control device from the main air cleaner that supplies air to the engine as well. The main air cleaner may be mounted at a conventional location on the frame for e.g. on the rear side of the frame.

In yet another aspect of the invention, a saddle type vehicle comprising
a frame having a head pipe, a main spine extending rearward from the head pipe and a plurality of downward and rearward extending down tubes;
an engine positioned within the space formed between the main spine and the plurality of down tubes; and
a secondary air injection system comprising a secondary air control device to control supply of secondary air within a secondary air supply path and a secondary air cleaner mounted on the frame, which supplies clean air to the secondary air control device;
wherein the secondary air control device is supported on at least two down tubes of the frame.
In another aspect of the invention, where the secondary air cleaner is provided for clean air supply to the secondary air injection system. The secondary air cleaner is mounted on rear side of the frame for e.g. on the seat frame.

In yet another aspect of the invention, the secondary air cleaner may mounted on the same mounting arrangement as that of the secondary air control device. In one such embodiment the secondary air cleaner is mounted on the same bracket on which the secondary air control device is mounted. The mounting bracket is suitably redesigned to enable mounting of both the secondary air control device and the secondary air cleaner. This eliminates the need of the additional bracket. Thus reducing the cost and material required. This also makes overall assembly more compact. Assembly of the secondary air cleaner and the secondary air control device can be formed as a separate subassembly which can be directly mounted on the frame. This also reduces time and effort involved in the assembly process.

In yet another aspect of the invention, where the secondary air cleaner is integrated with the main air cleaner and provided within the volume of the main air cleaner. In such arrangement the main air cleaner and the secondary air cleaner have common dirty side and separate volume for clean side.

The secondary air injection system described above allows improved packaging and performance of the exhaust gas control device. At the same time, the secondary air injection system described herein provides other benefits such as protection of the secondary air control device from dust, dirt, debris and water, preservation of vehicle aesthetics and ease of assembly and maintenance. Further, all the benefits are achieved without affecting position, function or performance of other vehicle components.

BRIEF DESCRIPTION OF DRAWINGS
In the drawings:

Figure 1 is a side view of a motorcycle including the secondary air injection system according to one embodiment of the present invention.

Figure 2 is an orthogonal view of a double cradle frame structure of the motorcycle in figure 1.

Figure 3 is a side view of the frame along with the components accommodated within frame of the motorcycle of the figure 1.

Figure 4 is an orthogonal view of the frame along with a mounting bracket for the secondary air control device.

Figure 5A is a front orthogonal view of the frame along with the bracket mounted with the secondary air control device.

Figure 5B is a front view of the frame along with the bracket mounted with the secondary air control device.

Figure 5C is a rear orthogonal view of the frame along with the bracket mounted with the secondary air control device.

Figure 6 is a schematic of the secondary air injection system along with secondary air control device and its associated tubing connections.

Figure 7 is a side view of the schematic of the secondary air injection system along with secondary air control device and its associated tubing connections.

Figure 8 is an orthogonal view of the secondary air control device showing tubing position relative to secondary air control device.

Figure 9 is a schematic of the secondary air injection system according to one of the embodiments of the invention where main air cleaner is used to provide clean air to secondary air control device.

Figure 10 is a schematic of the secondary air injection system according to one of the embodiments of the invention where secondary air cleaner is used to provide clean air to secondary air control device.

Figure 11 an orthogonal view of the assembly of the secondary air control device and its supporting bracket.

Figure 12 an exploded view of the assembly of the secondary air control device and its supporting bracket.

Figure 13 a sectional view of the secondary air control device.

DETAILED DESCRIPTION

Description of preferred but non-limiting embodiments of the secondary air injection system of the present invention will now follow with reference to the above drawings.

Referring first to Figures 1 to 3, there is shown a motorcycle 100 having a frame 110 and front forks 105. Front wheel 70 is connected to front forks 105 in conventional manner. The frame 110 of the motorcycle 100 comprises a head pipe 115, a main spine 120 extends rearward from the head pipe 115, a seat frame 130 connected to the main spine 120 and extending rearward and pair of down tubes 125 extending downward and rearward from the head pipe 115. The down tubes 125 are connected to the seat frame 130 on the rear side forming a hollow space 135 within the head pipe 115, the main spine 120 and the down tubes 125 for accommodating other vehicle components such as engine, air cleaner, etc. The down tubes 125 may be connected to each other using cross bars 127 at one or more locations which imparts strength.

A fuel tank 60 is mounted on the main spine 120 and a seat 90 is mounted on the seat frame 130 in a conventional manner. An engine 50 along with the transmission 160 is mounted on the down tubes 125 of the frame 110. Rear wheel 80 is connected to the frame 110 through a swing arm 52 and a rear suspension 54. An air cleaner 150 is mounted on rear side of the main spine 120 with the help suitable mounting arrangement for e.g. bolting arrangement. A carburetor 152 is provided which is connected to the air cleaner 150 to provide air fuel mixture to an engine intake manifold 51. A sleeve 154 connects the engine intake manifold 51 and the carburetor 152. The sleeve 154 acts as insulation and protects the carburetor 152 from heat of the engine intake manifold 51.

In order to reduce concentrations of HC and CO in exhaust gas from the engine 50, a secondary air injection system is provided which oxidizes exhaust gases using secondary air provided through the system. The secondary air injection system includes a secondary air control device 200 and its associated tubing which connects it with the air cleaner 150, the intake manifold 51 and an engine head 49.

Referring to Figures 4 to 5C, a mounting bracket 190 is provided to mount the secondary air control device 200. The mounting bracket 190 in mounted on the down tubes 125 of the frame 110. The mounting bracket takes the support of both the down tubes 125 and mounted across the down tubes 125. The mounting bracket 190 may be attached to the down tubes 125 by various attaching methods for e.g. welding, bolting, etc. While positioning the secondary air control device 200 on the frame 110, the secondary air control device 200 is attached to the mounting bracket through suitable attaching arrangement such as bolting, gluing, welding, etc. In another aspect of invention, the secondary air control device 200 and the mounting bracket 190 may be formed as integral assembly.

The mounting bracket 190 is arranged such that the secondary air control device 200 can be provided desired orientation so that various connection nozzles of the secondary air control device 200 are in positions which allows easier routing of tubes connecting the secondary air control device 200 with the air cleaner 150, the intake manifold 51 and an engine head 49

As the mounting bracket 190 is attached to both the down tubes 125, it does not get affected by the vehicle vibrations and provides a firm support to the secondary air control device 200. Further, due to such arrangement the secondary air control device does not have any overhang. This ensures a stiffer mounting of the secondary air control device 200, reduced chances of mechanical failures and improved NVH performance of the assembly.

The location and orientation of secondary air control device 200 is such that it does not affect the flow of the ram air coming to the engine 50. Further, the span between the down tubes 125 of the frame 110 is designed such that secondary air control device 200 can be accommodated without affecting ram air and vehicle aesthetics. Thus, cooling of the engine 50 and vehicle aesthetics are not affected due to position of the secondary air control device 200. Further, the position of secondary air control device 200 is such that it allows easy assembly, repair and maintenance of engine 50 and other vehicle components. This is achieved by carefully designing span between down tubes 125, the mounting bracket 190 and design of tube routing from the secondary air control device 200.

As the secondary air control device 200 remain behind the mudguard 102 and within the down tubes 125 of the frame 110, it remains protected from external adverse weather conditions such as dust, debris, dirt, water, etc. This also prevents any direct mechanical impact on the secondary air control device 200. As the secondary air control device 200 remains behind the mudguard 102 and within the down tubes 125, it is barely visible. Thus, it does not affect the overall aesthetics of the motorcycle 100.

Referring to Figures 6 to 9 and Figures 11 to 13, now the schematic of the secondary air injection system and its working are explained. The secondary air control device 200 is in the form of a one way valve which allows the flow of the secondary air only in one direction. In one of the embodiments, the secondary air control device includes a hollow body 205 within which a spring loaded diaphragm 206 is placed to allow one way flow of the secondary air. The secondary air control device has three nozzles namely an air filter connection nozzle 225, an intake manifold nozzle 235 and an exhaust nozzle 215. All the nozzles are in fluid communication with the hollow body 205 of the secondary air control device 200.

The air filter connection nozzle 225 is connected to a clean side of the air cleaner 150 through a tube 220 which carries a clean air from the air cleaner 150 to be injected in exhaust gas of the vehicle. The intake manifold nozzle 235 is connected to the intake manifold 51 of the engine 50 through a tube 230. This connection communicates pressure drop in the intake manifold 51 to the diaphragm 206 in the body 205 of secondary air control device 200 based on which the diaphragm 206 remain opens or close to allow or stop the flow of the secondary air.

The exhaust nozzle 215 of the secondary air control device 200 is connected to the engine head 49 through tube 210. A hole is provided in the engine head such that the secondary air carried by the tube 210 is released just outside the exhaust gas in order to oxidize the unburnt fuel residues in the exhaust gas to reduce the amount of pollutant in the exhaust. The tube 210 can be connected to exhaust pipe, however temperature in the exhaust pipe is lower than in engine head. Due to which the oxidation of unburnt fuel may not happen and desired effect of reducing pollutant in the exhaust in may not be achieved.

The bends of the tubes 210, 220 and 230 are designed such that they do not foul with the other vehicle components or cause inconvenience during assembly and maintenance of the vehicle components. Further, as the tubes 220 and 230 from the secondary air control device 200 which goes towards rear side of the vehicle have to pass through high heat region. To protect tubes 220, 230 from high heat, tubes 220, 230 are passed along the main spine 120 of the frame 110 and supported by main spine 120 to keep them out of hot zone. This arrangement also keeps tubes 220, 230 concealed and vehicle aesthetics is preserved. Further, routing tube 220 connection with the air cleaner 150 is designed such that it won’t foul with fuel tank 60 and get damaged. The damage to the routing tube 220 due to rubbing with fuel tank edge can be avoided by provided with rubber beading (not shown) to the fuel tank edge.

During the working of the secondary air injection system when the engine 50 is operating at lower rpm for e.g. 200 rpm, the speed of air in the intake manifold 51 is low and pressure is high. Due to which the diaphragm 206 under pressure from the intake manifold and the tension of spring 207 remains open and secondary air from the air cleaner 150 travel through the secondary air control device 200 in to the engine exhaust. However, when the engine speed increases, the velocity of air in the intake manifold 51 increases and pressure reduces. This lead to pressure drop in the body 205 of the secondary air control device 200 and diaphragm 206 closes and stops the flow of the secondary air.

In one of the embodiments of the invention for mounting of the secondary air control device 200 on the mounting bracket 190, bolting arrangement is provided. The mounting bracket 190 has two holes 191 and the body 205 of secondary air control device 200 is also provide with the matching holes 251 through which bolts 250 pass. For the firm mounting and prevent effect of vibration, the holes 191 of the mounting bracket 190 are provided with rubber grommets 270. The rubber grommets are covered with metallic bushes 260 from both sides to distribute the force on the rubber grommets 270 uniformly. Finally assembly is secured with nuts 280 on the other end of the bolts 250.

In an another embodiment of the invention, referring to Figure 10, the secondary air to the secondary air control device 200 is provided from the secondary air cleaner 300. The secondary air cleaner is attached to the rear side of the frame 110 at a suitable location for e.g. on the seat frame 130 using a suitable mounting arrangement such as bracket and bolts. In this case the air filter connection nozzle 225 is connected to a clean side of the secondary air cleaner 300 through a tube 220 which carries a clean air from the secondary air cleaner 300 to be injected in exhaust gas of the vehicle. Rest of the assembly works in the same way. Provision of secondary air cleaner 300 provides the liberty to accommodate the secondary air cleaner 300 anywhere on the frame where free space is available. Further, this arrangement also helps in cases where increasing the capacity of main air cleaner is not possible.

In yet another embodiment the secondary air cleaner 300 can be mounted on the same mounting bracket 190, as that of the secondary air control device 200. The design of the mounting bracket 190 is suitably modified for mounting of the secondary air cleaner 300 and the secondary air control device 200. Thus reducing the cost and material required. This also makes overall assembly more compact. Assembly of the secondary air cleaner and the secondary air control device can be formed as a separate subassembly which can be directly mounted on the frame. This also reduces time and effort involved in the assembly process.

The secondary air injection system described above has number of advantages such as it allows improved packaging and performance of the exhaust gas control device, protection of the secondary air control device from dust, dirt, debris and water, preservation of vehicle aesthetics and ease of assembly and maintenance. Further, all the benefits are achieved without affecting position, function or performance of other vehicle components.

Modifications and variations to the secondary air injection system described may be apparent to the skilled reader of this specification. Such modifications and variations are deemed within the scope of the present invention. The applicant intends to rely on the provisional specification and drawings annexed to the provisional specification.
,CLAIMS:WE CLAIM:
1. A secondary air injection system for a saddle type vehicle:

the saddle type vehicle comprising a frame having a head pipe, a main spine extending rearward from the head pipe and a plurality of downward and rearward extending down tubes; an engine positioned within the space formed between the main spine and the plurality of down tubes; and
the secondary air injection system comprising a secondary air control device to control supply of a secondary air within a secondary air supply path;
wherein the secondary air control device is supported on at least two down tubes of the frame.

2. The secondary air injection system for the saddle type vehicle according to claim 1 wherein the secondary air control device is at least partially ahead of an engine cylinder.

3. The secondary air injection system for the saddle type vehicle according to claim 1 wherein the secondary air control device is at least partially behind the down tubes and at least partially under the main spine.

4. The secondary air injection system for the saddle type vehicle according to claim 1 wherein the secondary air control device is at least partially under the headlight.

5. The secondary air injection system for the saddle type vehicle according to claim 1 wherein the frame is a double cradle type frame.

6. The secondary air injection system for the saddle type vehicle according to claim 1 wherein the secondary air control device is mounted on the down tubes of the frame using a mounting bracket.

7. The secondary air injection system for the saddle type vehicle according to claim 6 wherein the secondary air control device is attached to the mounting bracket using bolt or adhesive or welding or any combination thereof.

8. The secondary air injection system for the saddle type vehicle according to claim 6 wherein the secondary air control device and the mounting bracket are formed integrally.

9. The secondary air injection system for the saddle type vehicle according to claim 1 wherein clean air to the secondary air control device is provided by a main air cleaner that supplies air to the engine as well.

10. The secondary air injection system for the saddle type vehicle according to claim 1 wherein clean air to the secondary air control device is provided by a secondary air cleaner.

11. The secondary air injection system for the saddle type vehicle according to claim 10 wherein the secondary air cleaner is mounted on rear side of the frame.

12. The secondary air injection system for the saddle type vehicle according to claim 10 or 11 wherein the secondary air cleaner is integrated with a main air cleaner and provided within the volume of the main air cleaner such that the main air cleaner and the secondary air cleaner have a common dirty side and separate volumes for clean sides.

13. The secondary air injection system for the saddle type vehicle according to claim 6 and 10 wherein the secondary air cleaner is mounted on the same mounting bracket on which the secondary air control device is mounted.