Clutch force equaliser

Field of the invention

The present invention relates generally to a clutch and more particularly to a clutch force equaliser mechanism for reducing the force needed to operate a manually operated clutch lever of a motor vehicle.

Background of the invention

A motor vehicle typically includes an internal combustion engine which imparts power to a transmission for driving the vehicle. The transmission has several gear ratios which an operator of the vehicle may put to use depending on the driving conditions. The engine power is transferred to the transmission through a clutch. The clutch typically provides a mechanical coupling between the engine and transmission, and aids transfer of power and torque from the engine to the transmission by helping in shifting among various gear ratios. It coordinates smooth engagement of the spinning engine to the non-spinning transmission by controlling the slippage between them and hence allows the vehicle to stop without killing the engine.

A clutch can either be in engaged position or in disengaged position. When the clutch is engaged i.e. connected to the engine crankshaft, the transmission transfers torque from the engine crankshaft to one or more wheels of the vehicle. When the clutch is disengaged i.e. disconnected to the engine crankshaft the transmission is decoupled from the engine and do not transfer a driving torque to the wheel(s).

Conventional clutches include a friction type clutch that is normally held in engaged mode by a clutch spring. It is actuated through a manually operated clutch actuation lever, usually operated by left hand thereof. The clutch actuation lever is pivotally mounted to a handle bar of the vehicle adjacent to a hand grip on the handle bar and is connected to clutch by means of a clutch wire (or clutch cable). The manual operation requires an operator to grip the clutch lever and pull it back towards him. The pullback operation actuates the clutch to a disengaged position. After selecting a desired gear ratio, the operator releases his grip upon the clutch lever and the clutch gets engaged again. This manual operation provides a sense of controlling the operation of the vehicle to the operator and hence forms a necessary part of a majority of vehicles.

In developing countries, motor vehicles specially three wheeled vehicles are a significant mode of public transportation in rural and urban areas. If the vehicle stops at a traffic signal, the operator may shift the transmission into neutral and leave the clutch disengaged. But this is hardly practiced.

Generally hand operated clutch levers in these vehicles are put to heavy use owing to various road as well as traffic conditions. The operator keeps the clutch disengaged so that he may shift the vehicle to a suitable gear as the traffic signal turns green to enjoy a swift acceleration from a stop condition. However in order to keep the clutch disengaged, the operator has to keep the clutch lever retracted which corresponds to a continuous manually applied force. Repetitive retraction and release of clutch lever to disengage and engage the clutch leads to severe hand fatigue to the operator. More such actions subsequently result in an uncomfortable and painful riding experience.

To reduce the operator fatigue, an ergonomic clutch actuator has been previously proposed to reduce the force necessary to actuate the clutch lever in the U.S Pat. No. 7,150,348. It discloses a clutch actuator assembly having a clutch actuator mechanism, including a cam and a lever arm, driven by the clutch cable so that when the cable is drawn, the clutch actuator mechanism biases the clutch shaft and disengages the clutch and when the cable is released, the clutch shaft returns to engaged position. The input force by the operator increases and subsequently decreases as the clutch is disengaged. However this mechanism is housed inside the crankcase thereby consuming unnecessary space and is complex.

A need therefore exist for a simple yet user friendly mechanism that assists the force to be applied by the operator upon the clutch lever and which can be easily mounted on the vehicle.

Summary of the invention

The present invention is directed to overcoming one or more problems as set forth above. It is an objective of the present invention to provide an improved clutch force equaliser mechanism that can be employed by an operator of a motorized vehicle effortlessly and conveniently. The mechanism caters to a two wheeler as well as a three wheeler and in accordance with one embodiment thereof, includes a clutch operating means including a clutch actuation lever pivotally mounted on a handle bar of the said motor vehicle; a connecting arm connecting the clutch operating means to the rest of the said clutch force equaliser mechanism through a clutch cable located inside the said connecting arm such that retraction of the clutch operating means pulls up the clutch cable and actuates the clutch force equaliser mechanism so as to disengages a clutch located inside a crankcase of an internal combustion engine. and release of the clutch operating means releases the clutch cable so as to engage the said clutch; a plurality of mounting brackets for holding the said clutch actuation mechanism; and a spring assembly for operating the said clutch equaliser mechanism, wherein the spring assembly is operably connected to the said connecting arm through a clutch arm and the said spring assembly, when actuated by the clutch operating means, provides mechanical advantage by producing an assisting force which aids an operator of the said vehicle applying the force on the clutch operator means.

Another objective of the present invention Is to provide a clutch actuation mechanism that Is not limited with respect to In which vehicle it can be fitted and which can be mounted on the existing vehicles without major vehicle configuration modifications.

Yet another objective of the present Invention Is to disclose a clutch actuation mechanism where the Input force applied upon clutch actuation lever is reduced thereby reducing the operator fatigue during long drives and providing better driving comfort.

The foregoing objectives and summary provide only a brief Introduction to the present Invention. To fully appreciate these and other objects of the present invention as well as the Invention itself, all of which will become apparent to those skilled In the art, the ensuing detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the Invention will become apparent those skilled in the art from this detailed description.

Brief Description of the Drawings

Figure 1 is a perspective view of a vehicle, particularly a three wheeled passenger carrier vehicle, illustrating the application of clutch force equaliser mechanism according to the present invention thereto.

Figure 2 is a front view of the three wheeled vehicle with coverings and panels removed.

Figure 3 is a rear view of the three wheeled vehicle showing the internal combustion engine mounted on the posterior side of the three wheeled vehicle.

Figure 4 illustrates a side perspective view of a typical internal combustion engine assembly along with the clutch force equaliser mechanism according to an embodiment of the present invention.

Figure 5 shows the top view of the internal combustion engine along with the embodied clutch force equaliser mechanism of Figure 4.

Figure 6 is an enlarged top view of the embodied clutch force equaliser mechanism of Figure 4.

Figure 7 is the schematic view of the clutch force equaliser mechanism mounted on the internal combustion engine.

Figure 8 is elevational view of the mounted clutch force equaliser mechanism of Figure 4.

Figure 9 is another view of the mounted clutch force equaliser mechanism of Figure 4.

Figure 10 is a table showing the effectiveness of the embodied clutch force equaliser mechanism compared to the existing mechanism.

Figure 11 illustrates a side perspective view of a typical internal combustion engine assembly along with the clutch force equaliser mechanism according to a second embodiment of the present invention.

Figure 12 shows a schematic view of the second embodiment of the clutch force equaliser mechanism of Figure 11.

Figure 13 is a table showing the effectiveness of the second embodiment of the clutch force equaliser mechanism compared to the existing mechanism.

Detailed description of the invention

In the ensuing exemplary embodiments, the vehicle is a three wheeled vehicle. However it is contemplated that the concepts of the present invention may be applied to any motorized vehicle with a manual clutch operation including a motorcycle without defeating the spirit of the invention.

Further "front" and "rear", and "left" and "right" referred to in the ensuing description of the illustrated embodiment refer to front and rear, and left and right directions as seen in a state of being seated on a seat of the vehicle and looking forward. 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.

The present invention is now described briefly in connection with the rendered drawings. It should be noted that like elements are denoted by the same reference numerals throughout the description. The detailed explanation of the constitution of parts other than the clutch force equaliser mechanism which constitutes an essential part is omitted at opportune places.

Figure 1 describes a schematic view of a typical three wheeled vehicle, referenced by the numeral 100, driven by an internal combustion engine (not shown). It is commonly used as a passenger carrier. It has a front panel 101 along with a windscreen 102. The lower portion of the front panel is connected to a front wheel 104 with a wheel cover 103 stationed in between. A handle bar assembly 109 is present behind the front panel 101 which is used to operate the said three wheeled vehicle 100. The vehicle is laterally divided into two halves, along the line A-A, the first half having the driver's seat 107 while the second half has a long passenger seat 108 with a seating capacity of minimum three passengers. The rear panel 106 along with the second half of the vehicle containing the passenger seat 108 is supported on a pair of rear wheels 105 located on either side of the longitudinal axis of the vehicle 100. In this view, a steering tube assembly is not visible to an onlooker of the vehicle. Below the passenger seat, an internal combustion engine 300 is located used to power the vehicle.

Figure 2 illustrates the front view of the three wheeled vehicle with the panels and styling parts removed. The said three wheeled vehicle 100 is supported on a frame structure spanning from the first half to the second half of the vehicle. A front fork steering column assembly is connected to the front wheel 104 and comprises a steering column assembly, front suspension 203 and a trailing arm 204. The steering column assembly comprises of a steering column tube 202, rotatably supporting the front wheel 104 and acting as a mechanical link between a handle bar 109 and the front wheel 104. The steering column tube 202 is engulfed by a head pipe 205 on all sides and welded or secured to the head pipe. The head pipe usually houses bearings that allow the steering tube to turn freely. A clutch actuation lever 111 is pivotally mounted at a distal end of the handle bar 109 preferably on the left side thereof, such that the user may grip the handle bar and concurrently operate the clutch actuation mechanism (clutch force equaliser mechanism) by retracting and releasing the clutch actuation lever 111.

Figure 3 shows the rear view of the said three wheeled vehicle 100 with the rear panel removed and hence showing the otherwise invisible internal combustion engine 300 mounted on the posterior side of the vehicle frame below the passenger seat 108. The internal combustion engine 300 produces the necessary power which is then transferred to the transmission through a clutch (not shown). Since the basic construction of a clutch is known to those versed in the art, the details have been omitted.

Figure 4 shows an enlarged view of the said internal combustion engine 300 of the said three wheeled vehicle 100. It comprises a cylinder head 311, a cylinder block 312, a crank case assembly 313, the muffler 320 and the intake system 310. The said engine 300 has an intake system 310 including an air filter through which the air is sucked in. The air is mixed with the fuel and the air-fuel mixture is then ignited in the combustion chamber of the engine 300 thereby producing motive power. This motive power rotates the crankshaft (not shown) and is transferred to the wheel(s) through transmission. The transfer of this power from crankshaft to transmission is aided by the clutch positioned inside the crankcase opposite to flywheel (not shown). Further the exhaust gases move out of the combustion chamber during the exhaust stroke by the exhaust system which includes a muffler 320.

A clutch force equaliser mechanism 400 according to the present invention is now described in detail with the help of the Figures 4 to 13. An embodiment of the clutch force equaliser mechanism 400 is mounted at an appropriate location outside of the crankcase 313 of the said engine 300 as shown in Figure 4. It is operably connected to the clutch cable. The clutch actuation lever 111 is connected to the clutch by a clutch cable (not shown) through an intermediate clutch arm 406 located outside of the crankcase. Ordinarily when the clutch actuation lever 111 is in a. released state, the clutch wire is at rest and the clutch inside the crankcase is engaged by clutch springs (not shown) to transmit motive power to the transmission. In the usual case, the clutch springs would be contained within the clutch housing inside the crankcase, but the details have been omitted as clutch construction is not an essential part of this invention. When the clutch actuation lever 111 is gripped and pivoted towards the handle bar 109, the clutch wire is drawn, the clutch ami rotates about a revolute joint provided with a separate spring and hence the clutch is disengaged. In this disengaged position, no torque may be transmitted from the engine to the transmission through the clutch thus allowing the operator to select a desired gear of the transmission.

A clutch is biased to remain in engaged position through clutch springs. An operator of the said vehicle thus has to apply sufficient manual force upon the clutch actuation lever 111 to overcome the clutch spring force in order to disengage the clutch. Such repetitive action in heavy traffic conditions leads to operator fatigue and finger pain. It is also known that the clutch cable is a mechanical cable having a fixed distal end connected to the pivotal portion of the clutch actuation lever 111 and opposed distal end being fixed to the clutch arm 406. The external surface area of the clutch cable may be in contact with a clutch sheathing, thus creating cable friction when drawn which must also be overcome by the operator in order to actuate the clutch. The present invention reduces the force applied upon the clutch actuation lever 111 by the vehicle operator.

An enlarged view of a first embodiment of the clutch force equaliser mechanism is shown in Figure 6. It includes in addition to the aforementioned clutch actuation lever 111, a connecting arm 404 and a spring assembly. The components of clutch force equaliser mechanism 400 are held over the crankcase 313 with the help of a plurality of mounting brackets 411, 412 mounted at separate locations over the crankcase. The said brackets themselves are disposed over the crankcase through fasteners 414, 415 respectively. As shown by the arrow A, the connecting arm 404 connects the clutch actuation lever 111 to the rest of the clutch force equaliser mechanism 400. The connecting arm 404 functions as clutch cable housing and the clutch cable is contained inside it.

The spring assembly further comprises a floating pin, a fixed link, a link mechanism, a spring mechanism 405 and a spring lock mechanism 413. The link mechanism comprises of three amis namely first arm 401, second arm 402 and a third arm 403. The three arms are angularly disposed to each other when the operator pulls the clutch actuation lever. All these arms are pivoted with the help of a plurality of pivot points, referenced as PI, P2, P3, P4 and P5 and capable of rotation. All these pivot points are revolute joints and provide single axis rotation function. The spring assembly is connected with the clutch actuation lever at clutch actuation pivot point PI.

The spring mechanism 405 comprises of a tension spring 405 in the first embodiment. One end of the spring is held on the mounting bracket 412 and the other end is held by movable end of the third arm 403. The tension spring is preloaded so that it always tries to come back to its natural position. A spring pre load adjuster 416 is provided to adjust the preload of the spring 405. The preloaded spring can be locked into the selected preload through spring locking mechanism 413 using a hexnut by which the spring is held in its extended position.

The working of the said clutch force equaliser mechanism 400 is now explained with the help of Figures 6 - 9. Initially when the clutch actuation lever 111 is at rest, the first arm 401, second arm 402, third arm 403 and their pivots P3, P4 and P5 are in a straight line along their long axis. This alignment is important during the initial condition shown in Figure 7 as C1 when the clutch arm 406 is at its natural position. The preloaded spring 405 is retained in its position by the locking mechanism 413. The pulling force is balanced by a second tension spring 407 as shown in Figure 8.

When the operator of the three wheeled vehicle 100 pulls the clutch actuation lever 111 towards himself for disengaging the clutch in order to change the gear, the connecting arm 404 pulls clutch arm 406 towards itself. The clutch amri 406 then rotates about the pivot P5. As the clutch arm 406 rotates, it causes the first ami 401 to break out of the straight line and rotate along with the pivot P5. The resultant motion of the first arm 401 pulls the pivot P4 downwards as indicated by the arrow. In this way the second arm 402 and the first arm 401 become angularly disposed to each other as shown in Figure 7. The fixed end of the third arm 403 rotates around the pivot P2 due to the force exerted by revolute joint P3. The spring end of the third arm 403 is pushed towards the clutch arm direction as shown by the arrow. It further brings the preloaded tension spring 405 back to its natural position. This condition is shown in Figure 7 as C2. The clutch spring force tries to keep the clutch in the engaged position. The tension spring force and the force generated when the third arm 403 moves towards the clutch arm direction act opposite to the clutch spring force thereby assisting the operator and hence called assisting force. Due to the additional assisting force, the force required to squeeze the clutch actuation lever Ill reduces so that the operator may operate the disengagement of the clutch with reduced effort while obtaining the same result. Summarily the clutch spring force is equalised and overcome by a combination of the assisting force and manual force applied upon the clutch actuation lever. Moving forward, any increase in the preloading of the spring will further smoothen the operability of the clutch actuation lever. Figure 8 and 9 further provide additional views of this embodiment of the clutch force equaliser mechanism.

Figure 10 is a table showing the effectiveness of the first embodiment of the clutch force equaliser mechanism with tension spring compared to the existing clutch without the clutch force equaliser mechanism. When the clutch arm 406 rotates about the pivot P5 from its initial position (i.e. engaged position), it makes an angle relative to the pivot joint P5. The torque acting on the clutch shaft was calculated at different clutch arm angles. This torque is an indicator of the force that needs to be applied on the clutch actuation lever 111. The table shows that the torque at the clutch arm is less with the proposed mechanism after the clutch arm rotates 5 degrees compared to that without the proposed mechanism. While the total force required to disengage the clutch remains same, the assisting force generated aids the force applied by the operator and the required force is achieved by less applied force.

A second embodiment of the clutch force equaliser mechanism is further described below. Figure 11 shows a second embodiment of the same invention with a compression spring. The clutch force equaliser mechanism 500 with the compression spring is held onto the crankcase 313 of the internal combustion engine by a mounting bracket 412.

Figure 12 shows the detailed view of the second embodiment. The said mechanism is connected to the clutch actuation lever by a connecting arm (not shown) through a clutch arm (not shown) which is operated by a separate spring. A spring assembly is connected to this clutch arm, the said spring assembly comprising a floating pin 505, a fixed link 501, a link mechanism comprising a plurality of link arms namely a first link arm 504, a second link arm 506 pivoted by a pivot point 503, a spring mechanism comprising a preloaded compression spring 502 and a known spring lock mechanism to lock the said spring in the selected preload condition.

The said spring assembly is connected to the clutch arm through the second link arm 504 which is spin riveted around a floating pin 505. Initially both the link arms are in co-axially aligned when the clutch actuation lever is in released condition and the clutch is engaged. When the operator applies force on the clutch actuation lever, the clutch ann rotates as the clutch cable is drawn. The rotating clutch arm proportionately rotates the floating pin 505. In this way the second link ami 506 breaks away from coaxial state and now the two link arms are angularly disposed and capable of rotation around the pivot point 503. The second arm 506 pulls up the first arm due to which the preloaded compression spring 502 is released. It provides assisting force to the clutch arm rotation and hence aids the operator in holding the clutch actuation lever 111 in the disengaged condition for long.

Figure 13 provides a table where the torque at clutch shaft is measured alongside the clutch arm rotation angle. The table shows that the torque in the clutch force equaliser mechanism with compression spring decreases after 5 degrees rotation of the clutch arm compared to the existing without mechanism. Thus the effort by the operator on the clutch actuation lever is reduced and hence leads to better operator comfort.

From the forgoing description, it will be appreciated that the present invention offers many advantages. The invention reduces the force applied upon the clutch actuation lever by the operator of the vehicle which leads to easy gear shifting i.e. the force needed to operate a clutch can be reduced by the assistance provided by the present mechanism. The invention significantly improves the operator driving comfort by reducing the operator fatigue and finger pain. If the operator has to withhold the clutch actuation lever in squeezed condition for a fairly long time, for e.g., during traffic signal halts, or during heavy traffic, then the force applied by the operator is aided by the proposed clutch force equaliser mechanism thereby assisting him. Furthermore the said mechanism is easy to manufacture and since less machining operations are required, the cost incurred is less. While the invention can be fitted in the course of vehicle production, existing vehicles can also be readily retrofitted with the present invention. The invention is applicable to all motor vehicles comprising a clutch actuation lever, including a two wheeled and a three wheeled vehicle.

The terms and expressions in this specification are of description and not of limitation and do not exclude any equivalents of the features illustrated and described, but it is understood that various other embodiments are also possible without departing from the scope and ambit of this Invention which will become apparent to those skilled in the art from this detailed description. Accordingly, the description is to be understood as an exemplary embodiment and reading of the invention is not intended to be taken restrictively.

We claim:

1. An easy clutch force equaliser mechanism for a motor vehicle, the clutch force equaliser mechanism comprising:

a clutch operating means including a clutch actuation lever pivotally mounted on a handle bar of the said motor vehicle;

a connecting arm connecting the clutch operating means to the rest of the said clutch force equaliser mechanism through a clutch cable located inside the said connecting arm such that retraction of the clutch operating means pulls up the clutch cable and actuates the clutch force equaliser mechanism so as to disengages a clutch located inside a crankcase of an internal combustion engine, and release of the clutch operating means releases the clutch cable so as to engage the said clutch;

a plurality of mounting brackets for holding the said clutch actuation mechanism; and

a spring assembly for operating the said clutch equaliser mechanism, wherein the spring assembly is operably connected to the said connecting arm through a clutch arm and the said spring assembly, when actuated by the clutch operating means, provides mechanical advantage by producing an assisting force which aids an operator of the said vehicle applying the force on the clutch operator means.

2. The easy clutch force equaliser mechanism as claimed in claim 1, wherein the said spring assembly further comprises a floating pin, a fixed link, a link mechanism comprising a plurality of link amis pivoted by a plurality of pivot points, a spring mechanism comprising a preloaded spring and a spring lock mechanism to lock the said spring in the selected preload condition.

3. The easy clutch force equaliser mechanism as claimed in claim 1, wherein when the said clutch operating means is squeezed by an operator of the said vehicle, the link arms not directly connected with the spring mechanism are angularly disposed to each other thereby releasing the preloaded spring in the spring mechanism which in turn further moves one of the link arm directly connected with the spring mechanism, the force generated by said link arm directly connected with the spring mechanism overcoming the clutch spring force and thus providing mechanical advantage to the force applied by the operator upon the clutch operating means.

4. The easy clutch force equaliser mechanism as claimed in claim 1, wherein the said motor vehicle may be any vehicle comprising a clutch operating means, including a two wheeled vehicle or a three wheeled vehicle.

5. A clutch force equaliser mechanism for a motor vehicle which assists the force applied by an operator of the said vehicle on a clutch .actuation lever to disengage or engage a clutch with the help of a spring assembly, thereby reducing the operator fatigue, the said clutch force equaliser mechanism mounted on an internal combustion engine with the help of a mounting bracket.

6. A clutch force equaliser mechanism as claimed in claim 5, wherein the said spring assembly is operably connected to a connecting arm through a clutch arm, the said spring assembly comprising of a floating pin, a fixed link, a link mechanism comprising a at least two link arms pivoted by a pivot point, a spring mechanism comprising a preloaded compression spring and a spring lock mechanism to lock the said spring in the selected preload condition such that the rotation of clutch arm due to manual force on the clutch actuation lever generates an assisting force which counters the clutch spring force by angular disposition of the two link arms with respect to each other at a connecting pivot point and subsequent release of preloaded compression spring. 7. A clutch force equaliser mechanism substantially as claimed in any of the preceding claims and illustrated with reference to the accompanying drawings.