NON ELECTRICAL CHOKE

FIELD OF THE INVENTION

[0001] The present subject matter relates generally to a carburettor connected to an internal combustion engine, and more particularly, to a non-electrical choke valve operating mechanism for use in an automotive vehicle.

BACKGROUND OF THE INVENTION

[0002] Traditionally, a carburettor in an automotive vehicle comprises of a choke valve which controls the air flow into the carburettor and provides enriched combustible mixture to an internal combustion engine for powering the vehicle. The choke valve is of special significance when the vehicle is to be started during cold start conditions because the normal air fuel mixture is too lean for powering the cold engine.

[0003] Depending on the engine design and application, the choke valve can be operated either manually or automatically. However, both types of choke valve operating mechanisms have the same objective of providing rich mixture during cold start of the engine. A manually operated choke valve is controlled by an operator of the vehicle by pulling or pushing a choke operating lever connected to the choke valve through a cable. The said choke operating lever may be mounted on a handlebar of a motorcycle or lateral surface of the leg shield in a scooter type motorcycle. On the other hand, an electrically operated choke (also known as autochoke) works without manual intervention with the help of a temperature sensitive mechanism.

[0004] Both the choke valve operating mechanisms have their limitations. The electrically operated choke valve is critically dependent on electrical power source (battery) thereby making it less reliable in case of battery failure whereas manually operated choke valve requires the choke valve to be closed during vehicle running condition which makes it risky as the same is prone to operator's memory. In a scenario where the operator forgets to put the choke operator lever in its default position, it may lead to engine stalling and other ramifications as the choke operating lever doesnot have a fail safe mechanism. Furthermore for optimum efficiency, the choke operating lever needs to be held for some time before returning to its default position. Instant reversal to its default position will not allow sufficient time for the engine to warm up.

[0005] The present invention is directed to overcoming one or more problems as set forth above and obviate the lacunae in the prior art. It is therefore an object of the present invention to disclose a non-electrical, manually operated, time dependent choke valve operating mechanism for a naturally aspirated internal combustion engine. It is another object of the present invention to provide a low cost, easily operable, self retracting, stand alone mechanism for achieving the function of choke operation without being dependent on any electrical system or electrical power source. Yet another object of the present invention is to provide a choke operating lever assembly for a two wheeled vehicle that is efficient, cost effective, easy to operate and mounted on an automotive vehicle, preferably a scooter type automotive vehicle.

SUMMARY OF THE INVENTION

[0006] To this end, the present invention discloses a non-electric choke valve operating mechanism for controlling a choke valve of a carburettor annexed to a naturally aspirated internal combustion engine, the said choke valve operating mechanism comprising: a manually operable choke operating lever operable between a default position and a pulled position, a choke operating unit partially housing the choke operating lever, a partition wall partitioning the choke operating unit into at least two oil filled chambers, a first chamber and a second chamber, a helical spring attached to the choke operating lever at one end and to the partition wall at the other end, a plurality of oil seals to seal the oil filled chambers, a cable connecting the choke operating lever to the choke valve; wherein when the choke operating lever is manually operated from the default position to the pulled position, the helical spring is compressed and the oil flows from the first chamber to the second chamber through a one way valve and a metering channel, and wherein, the choke operating lever self-retracts to its default position through the helical spring and the oil flows from the second chamber to the first chamber through the metering channel.

[0007] According to an aspect of the present invention, the time taken by the choke operating lever to retract to its default position is dependent on the cross sectional area of the metering channel, volume of the oil passing through the metering channel and the compression of the helical spring.

[0008] According to another aspect of the present invention, the volume of oil passing through the metering channel during the retraction of the choke operating lever is controllable through a load adjusting screw threaded with the inner body of the choke operating lever.

[0009] 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

[00010] 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 straddle type vehicle with a swinging power unit according to the present invention.

FIG. 2 depicts a non-electrical choke operating mechanism according to the present invention, illustrating a state where a choke operating lever is in default position.

FIG. 3 shows a non-electrical choke operating mechanism according to the present invention, illustrating a state where the choke operating lever is in pulled position.

DETAILED DESCRIPTION OF THE INVENTION

[00011] In order that those skilled in the art can understand the present invention, the invention is further described below so that various features of the non electric choke operating mechanism thereof proposed here are discernible from the description thereof set out hereunder. However these descriptions and the appended drawings are only used for those skilled in the art to understand the objects, features, and characteristics of the present invention and not to be used to confine the scope and spirit of the present invention. In the supporting FIGs, the same reference numerals are given to members and parts having the same functions. In the ensuing exemplary embodiments, the vehicle is a straddle ride type vehicle like a scooter type motorcycle. However, it is contemplated that the concepts of the present invention may be applied to other types of vehicles within the spirit and scope of this invention like a motorcycle or a moped.

[00012] Further "front" and "rear", and "left" and "right" referred to in the ensuing description of the illustrated embodiment, except stated otherwise, refer to front and rear, and left and right directions as seen in a state of being seated on a seat of the vehicle. Furthermore, a longitudinal axis, except stated otherwise, refers to a front to rear axis relative to the vehicle, while a lateral axis, except stated otherwise, refers generally to a side to side, or left to right axis relative to the vehicle.

[00013] The present invention is now explained with the help of rendered FIGS. 1 to 3. FIG. 1 illustrates the side view of a concerned straddle ride type vehicle. 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 (power unit) 102. The frame assembly 101 of the straddle 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.

[00014] 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 106 for seating a driver and a pillion is placed forward to the fuel tank (not shown) and rearwardly of the floorboard 107. A fuel tank, for storing the fuel supplied to the engine, is disposed at the rear end of the vehicle above the rear wheel and the engine. A side stand, attached to the left side of the frame, is provided to the rear of the engine and supports the vehicle such that vehicle inclines to the left side.

[00015] 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.

[00016] 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.

[00017] In the said vehicle, the rear suspension swing arm typically supports the engine (power unit) 102 and a swing case 108. The engine and the swing case are integrally constructed for the embodied vehicle. In an embodiment of the present invention, the engine is a four stroke single cylinder engine and the swing case 108 is connected to a left side surface of a crankcase of the engine 102 so as to extend forward. 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. Since the basic construction of an engine is known to those versed in the art, the details have been omitted.

[00018] Usually during cold start conditions or during the first start of the. day, the engine is usually cranked by using a choke valve operating mechanism in order to provide a rich combustible mixture to the engine. In the scooter type vehicle, the choke valve operating mechanism is present laterally to the leg shield 116 towards the rider and is connected to the choke valve of a carburettor annexed to the internal combustion engine. The present invention focusses on a non electric, self-retracting choke operating mechanism present at the same location.

[00019] FIG. 2 describes a non-electric choke valve operating mechanism 200 according to the present invention. The said choke valve operating mechanism comprises of a manually operable choke operating lever 201 operable between a default position and a pulled position, a choke operating unit 210 partially housing the choke operating lever 201 having at least two oil filled chambers namely a first chamber CI and a second chamber C2 separated by a movable partition wall 211, a helical spring 204 attached to the choke operating lever 201 at one end and to the partition wall 211 at the other end, a plurality of oil seals 203a, 203b to avoid oil leak from the respective oil chambers and a cable 208 connecting the choke operating lever 201 to the choke valve. Further a metering channel 205, a one way valve 206 and a load adjusting screw 207 are also part of the present invention. The choke operating lever 201 is connected to and partially housed in the choke operating unit 210. The metering channel 205 and one way valve 206 are provided in the partition wall 211. According to a preferred embodiment, the cross sectional area of the one way valve 206 is more than the cross sectional area of the metering channel 205. The partition wall 211 is movable during operation and retraction of the choke operating lever. When the choke operating lever is manually operated from the default position to the pulled position, the helical spring is compressed and the oil flows from the first chamber CI to the second chamber C2 through the one way valve 206 and the metering channel 205. The choke operating lever 201 is capable to self-retract to its default position through the helical spring and the oil flows from the second chamber C2 to the first chamber CI through the metering channel 205 during the retraction. The time taken by the choke operating lever to self-retract to its default position is dependent on the cross sectional area of the metering channel 205, volume of the oil passing through the metering channel 205 and the compression of the helical spring 204.

[00020] The operation of the choke operating mechanism 200 according to the present invention is now described. Initially in its default position, the choke _ - • operating lever 201 is substantially inside the choke operating unit 210. According to an embodiment, the choke operating lever 201 is partially housed in the first chamber CI of the choke operating unit 210. FIG. 2 shows the choke operating lever 201 in default position or unpulled position where the choke valve is not operable. To bring the choke valve into operation, the choke operating lever 201 is manually pulled out by the rider of the vehicle using his fingers and thumb. FIG. 3 shows the choke operating lever 201 in pulled position. The outward movement of the choke operating lever 201 leads to compression of the helical spring 204 and subsequent movement of partition wall 211. This also causes the oil to flow from first chamber CI to second chamber C2, through the one way valve 206 and metering channel 205 simultaneously. Two different passages for oil flow through the one way valve 206 and metering channel 205 ensure smooth and instant opening of the choke valve when the pulling load is applied on the choke operating lever 201. The cable 208 connecting the choke operating lever 201 to the choke valve is compressed and choke valve is put to operation.

[00021] The choke operating lever 201 is self retracting. Once the choke operating lever 201 is pulled and then released by the rider, it starts retracting gradually to its default position due to the return force from helical spring 204. During the return operation, oil flows from second chamber C2 to first chamber CI through metering channel 205 alone as the one way valve 206 is closed during this movement of the choke operating lever 201. As the cross sectional area of the metering channel 205 is only a fraction of one way valve cross sectional area, the return flow of oil from chamber C2 to chamber CI is slow and hence the metering channel 205 acts to dampen the motion of the choke operating lever 201.

[00022] The time taken by the choke operating lever 201 to retract to its default position is dependent on the cross sectional area of the metering channel, volume of the oil passing through the metering channel and the compression of the spring. The time taken by choke operating lever 201 to return to its default position can be controlled and set by the load adjusting screw 207 by changing the metering channel's cross sectional area. The load adjusting screw 207 spans along the length of the choke operating lever and is threaded with the inner body of the choke operating lever 201 and can be moved in or out by rotating the head of load adjusting screw 207. The tightening and loosening of the load adjusting screw can open or close the metering channel and hence the volume of oil passing through the metering channel during the retraction of the choke operating lever is controllable through the load adjusting screw. When the choke operating lever 201 retracts completely, the choke stops functioning.

[00023] The non-electric choke operating mechanism 200 according to the present invention can be manually adjusted depending upon the environmental and vehicle conditions. It controls the time for which choke valve remains in operation. Further even if the vehicle operator forgets to revert the choke operating lever to its default position, the choke operating lever automatically retracts as it is spring loaded. Furthermore, since no electrical parts are required, the present invention offers incidental advantage of less cost. The present invention thus allows all the advantages of an auto choke system at a lower cost and to design a choke operating system independent of electrical energy.

[00024] 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 non-electric choke valve operating mechanism for controlling a choke valve of a carburettor annexed to a naturally aspirated internal combustion engine, the said choke valve operating mechanism comprising:

a manually operable choke operating lever operable between a default position and a pulled position,

a choke operating unit partially housing the choke operating lever,

a partition wall partitioning the choke operating unit into at least two oil filled chambers,

a first chamber and a second chamber,

a helical spring attached to the choke operating lever at one end and to the partition wall at the other end,

a plurality of oil seals to seal the oil filled chambers,

a cable connecting the choke operating lever to the choke valve,

wherein when the choke operating lever is manually operated from the default position to the pulled position, the helical spring is compressed and the oil flows from the first chamber to the second chamber through a one way valve and a metering channel,
and wherein, the choke operating lever self-retracts to its default position through the helical spring and the oil flows from the second chamber to the first chamber through the metering channel, and wherein further, the time taken by the choke operating lever to self-retract to its default position is dependent on the cross sectional area of the metering channel, volume of the oil passing through the metering channel and the compression of the spring.

2. The non-electric choke valve operating mechanism as claimed in claim 1, wherein the volume of oil passing through the metering channel during the retraction of the choke operating lever is controllable through a load adjusting screw.

3. The non-electric choke valve operating mechanism as claimed in claim 2, wherein the load adjusting screw spans along the length of the choke operating lever and is threaded with the inner body of the choke operating lever.

4. The non-electric choke valve operating mechanism as claimed in claim 1, wherein the choke operating lever is partially housed in the first chamber of the choke operating unit.

5. The non-electric choke valve operating mechanism as claimed in claim 1, wherein the partition wall is movable during operation and retraction of the choke operating lever.

6. The non-electric choke valve operating mechanism as claimed in any of the preceding claims, wherein the metering channel and the one way valve are connected to the partition wall.

7. The non-electric choke valve operating mechanism as claimed in claim 1, wherein the cross sectional area of the one way valve is more than cross sectional area of the metering channel.

8. A straddle type vehicle comprising the non-electric choke valve operating mechanism as claimed in any of the preceding claims.