DESC:FIELD OF THE INVENTION
[0001] The present invention relates generally to an internal combustion engine. More particularly, but not exclusively, to a clutch actuation measurement for a vehicle provided with an engine having automatic transmission.
BACKGROUND OF THE INVENTION
[0002] Generally, most of the two-wheeled vehicles have a manual transmission system to carry the power generated by an internal combustion (IC) engine, in a controllable way, to a wheel of the vehicle. The manual transmission system comprises a system of interlocking gears such that by operating a gearshift lever manually, the driver can choose one of the several ratios of speed between the input shaft and the output shaft. To allow smooth and gradual shifting of gears, a clutch is provided to isolate the engine from the transmission momentarily. When the driver releases the clutch lever manually, the discs in the clutch assembly are squeezed with each other and thus the transmission is engaged with the engine.
[0003] Off lately, automated manual transmission (AMT) systems have come into use for ease of operation of clutch actuation and gearshift. The ride on such vehicle is less tiring for the vehicle rider. Conventionally, a vehicle fitted with an AMT engine has electrically controlled clutch operation and gearshift operation powered by a battery and controlled by a controller.

BRIEF DESCRIPTION OF DRAWINGS
[0004] 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:
[0005] FIG. 1 illustrates a side view of an IC engine with an automatic clutch according to the present invention.
[0006] FIG. 2 shows an exploded view of an embodiment of the clutch disposed internal to a clutch cover according to the present invention.
[0007] FIG. 3 shows a rear perspective view of a clutch position sensor functionally engaged with a clutch.
[0008] FIG. 4 shows a sectional view of the clutch position sensor functionally engaged with a clutch.
[0009] Fig. 5 illustrates a detailed view of a sectional view of the clutch actuation sensor connected to the actuator plunger.
DETAILED DESCRIPTION OF THE INVENTION
[00010] Typically, an internal combustion engine in a two-wheeled vehicle includes a crankcase assembly divided into two crankcase halves, a crank chamber being defined and formed by the crankcase halves, a crankshaft housed in the crank chamber and a cylinder block connected to the crankcase. A clutch cover is arranged towards the right so that it is adjacent to the crankcase in the vehicle width direction. A counter shaft is arranged in the crankcase halves flanked by transmission cover, the rotation of the crankshaft being transmitted to the counter shaft. A drive shaft is arranged rearward or upward of the counter shaft in the crankcase halves, the driving wheel being attached to the drive shaft through chain and sprocket means. The counter shaft is connected to the drive shaft through a gearbox. The gears in the gearbox are shifted by a gearshift actuator selecting the desired gear ratio to be given to the drive shaft by actuating the clutch by a clutch actuation system.
[00011] According to an embodiment of the present invention, the clutch actuation system is positioned laterally to the engine towards the clutch side substantially inside a clutch cover. The clutch cover is adjacent to the crankcase along the lateral axis of the engine. The clutch actuation system according to the present invention includes a clutch actuation motor, a plurality of reduction gears attached to the actuation motor, a power transmission mechanism which transmits the rotational driving force of the actuation motor, and a clutch actuation sensor which detects the actuation of the clutch, a thrust bearing, and a washer.
[00012] The power transmission mechanism comprises of a worm wheel, an actuator plunger having a raised lug provided with an extended shaft, a set of caged ramp balls and a return spring. The power transmission mechanism transmits rotational driving force of the said motor to a clutch release pin through the worm wheel arrangement thereby engaging and disengaging the clutch without any manual intervention.
[00013] The reduction gearbox includes a worm gear driven by a motor shaft projecting out from the actuation motor and the worm wheel is mated with the worm gear. The worm wheel includes multiple segmented and ramped circumferential grooves provided on one of its surfaces. Each groove varies in depth along its length. The worm wheel is coaxially held with the actuator plunger, the actuator plunger also has similar grooves on one of its surfaces facing the worm wheel. The worm gear is supported interior to the clutch cover in worm gear housing.
[00014] The rack and pinion arrangement is provided to substantially restrict the rotational movement of the actuator plunger. It is secured to the inner surface of the clutch cover and is constructed in such a way that it restricts the rotational movement of the actuator plunger while allowing the linear movement of the raised lug of the actuator plunger.
[00015] The controller is programmed to drive the actuation motor to the riding conditions (e.g. engine r.p.m, throttle position etc.). The reduction gears including the actuator plunger and the worm wheel reduces the output of the actuation motor to optimally rotate the motor shaft. The motor shaft in turn rotates the worm gear, which subsequently rotates the worm wheel. When the motor shaft of the actuation motor rotates through a desired number of complete revolutions, it results in a certain angular displacement in the worm wheel. The resulting angular displacement can be classified into several quadrants. As the worm wheel advances towards the actuator plunger, the resultant force on the worm wheel drives the ball and ramp mechanism to convert the rotary movement into a linear displacement on the clutch assembly. The actuator plunger is rotationally held static in relation to the worm wheel and the ramped circumferential grooves present in worm wheel as well those in actuator are rotated relative to each other through the caged balls. In other words, the caged balls running in the segmented and ramped circumferential grooves cause two opposite components to separate as the balls advance on the grooves as a result of any imposed angular displacement. The rotating balls traverse from high depth to low depth in the circumferential grooves. This mechanism provides the conversion from rotary to linear displacement.
[00016] The extent of angular movement of the worm wheel is detected by the clutch actuation sensor and is fed into the controller, which then signals the clutch engagement after gearshift operation. The clutch actuation sensor is connected to the actuator plunger. Hence, the angular movement of the worm wheel is indirectly sensed through actuator plunger.
[00017] At certain situations, whenever failure occurs in working of the parts disposed in between the sensor and the worm wheel, the angular movement sensor may provide wrong inputs to the controller. The angular movement sensor malfunctions whenever there occurs slipping of the caged ramp balls, which in turn affects the functioning of the plunger actuator and the worm wheel. Resulting in providing poor ride quality to the user. These are the drawbacks involved in the conventional type angular movement sensor connected to the actuator plunger to sense the movement of the worm wheel.
[00018] Hence, it is an objective of the present invention to provide more accurate inputs from the worm wheel to the controller through a movement sensor. The more accurate inputs to the controller from the movement sensor results in appropriate automatic shift of the gears thereby providing good quality ride feel to the user.
[00019] The previously mentioned drawbacks can be overcome by the proposed invention. According to an embodiment of the present invention, the angular movement sensor is replaced by a linear movement sensor. Detecting the position of the clutch is critical to detect the gearshift in the vehicle. The position of the clutch is known by detecting the position of the actuator plunger. The linear movement sensor directly measures the movement of the actuator plunger. Any interfering parts that lie in between the sensor and the actuator plunger are avoided. Hence, the sensor is directly connected to the actuator plunger and the liner movement is directly measure. Hence, avoiding errors occurring from the interfering parts including worm gear, worm wheel, and slipping of the caged ramp balls.
[00020] The present invention disclosed herein is usable with an engine with an automatic, electrically operated clutch. It is to be noted that “front” and “rear”, unless mentioned otherwise, refer to front and rear directions as seen in a state of being seated on a seat of the vehicle carrying the present invention and looking forward. Such vehicle is installed with the engine with its cylinder head facing towards the front. Further, “left” and “right”, unless mentioned otherwise, refer to left and right directions of an onlooker standing in front of the vehicle and looking towards it. A lateral axis refers generally to a side-to-side, or left to right axis relative to the vehicle. Various other features of the present subject matter here will be discernible from the following further description thereof, set out hereunder.
[00021] FIG. 1 and FIG. 2 respectively illustrates a side view and exploded view of an IC engine 100 having a cylinder head 101 and a transmission system disposed internal to a clutch cover 102. The transmission system has an automatic clutch 139 connected to the engine and covered by the clutch cover 102. The clutch cover 102 has an inner surface 104 facing towards the clutch 139 and an outer surface 103 opposed to the inner surface 104. The clutch actuation system for automatically actuating the operation of clutch engagement and disengagement includes a clutch actuation motor 105, a reduction gear box comprising of a plurality of reduction gears attached to the clutch actuation motor 105, a power transmission mechanism which transmits the rotational driving force of the clutch actuation motor 105, a clutch position sensor 111 which detects the actuation of the clutch, a thrust bearing 106, a ball bearing 107 and a washer. The clutch actuation motor 105 is mounted and secured to an outer surface of the clutch cover 102 and sealed against ingress of oil. The clutch actuation motor 105 is electrically connected to a controller (not shown) which may be programmed to control the direction of rotation of the clutch actuation motor 105 as well as the time duration of its operation.
[00022] As shown in FIG. 2, the automatic clutch 139 is electrically operated through the clutch actuation motor 105 via the power transmission mechanism which comprises of a worm gear 108 operatively meshed with a worm wheel 110. The worm wheel 110 in turn is functionally connected to an actuator plunger 115. In a preferred embodiment, the actuator plunger 115 is a circular plate structure engaged on its one side with the worm wheel 110 through a ramped ball mechanism. A plurality of ramped balls 114 are caged in a ball holding member 113 disposed between the actuator plunger 115 and the worm wheel 110. In this way, the actuator plunger 115 takes rotational driving force from the worm wheel 110 through the ramped ball mechanism and operates a clutch release pin thereby engaging and disengaging the clutch 139 without any manual intervention. The clutch 139 works with the help of a clutch plate assembly 138 through which it is engaged to and disengaged from a primary driven gear 140 taking its drive from a crankshaft of the engine.
[00023] Fig. 3 and Fig. 4 illustrate a rear perspective view and a sectional view of a clutch position sensor functionally engaged with a clutch. The section is taken along ab plane as illustrated in Fig. 3. The clutch actuation system according to the present invention includes a clutch actuation motor 105, a reduction gear box comprising of a plurality of reduction gears attached to the actuation motor 105, a power transmission mechanism which transmits the rotational driving force of the actuation motor 105, and a clutch actuation sensor 111 which detects the actuation of the clutch 139, a thrust bearing, and a washer.
[00024] The power transmission mechanism comprises of a worm wheel 110, an actuator plunger 115, a set of caged ramp balls and a return spring 124. The power transmission mechanism transmits rotational driving force of the actuation motor 105 to a clutch release pin 137 through the rack and pinion arrangement thereby engaging and disengaging the clutch 139 without any manual intervention.
[00025] A controller is programmed to drive the actuation motor 105 to the riding conditions (e.g. engine r.p.m, throttle position etc.). The reduction gearbox reduces the output of the actuation motor 105 to optimally rotate the motor shaft. The motor shaft in turn rotates the worm gear 108, which subsequently rotates the worm wheel 110. When the motor shaft of the actuation motor rotates through a desired number of complete revolutions, it results in a certain angular displacement in the worm wheel 110. As the worm wheel 110 advances towards the actuator plunger 115, the resultant force on the worm wheel 110 drives the ball caged in the ball holding member 113 and ramp mechanism to convert the rotary movement into a linear displacement on the clutch 139. The actuator plunger 115 is rotationally held static in relation to the worm wheel 110 and the ramped circumferential grooves present in worm wheel 110 as well those in actuator plunger 115 are rotated relative to each other through the caged balls. In other words, the caged balls running in the segmented and ramped circumferential grooves cause two opposite components to separate as the balls advance on the grooves because of any imposed angular displacement. The rotating balls traverse from high depth to low depth in the circumferential grooves. This mechanism provides the conversion from rotary to linear displacement. The linear displacement of the actuator plunger 115 occurs. Further, the linear displacement is transferred to the clutch release pin 137 through an extended portion 116.
[00026] The extent of linear motion of the actuator plunger 115 is an important factor for gear shifting operation to be carried out by the controller. Hence, the linear motion being a critical input to the controller, an appropriate and accurate input from the actuator plunger 115 has to be fed to the controller.
[00027] Therefore, according to an embodiment of the present invention, the extent of linear movement of the actuator plunger 115 is directly detected by the clutch actuation sensor 111 and is fed into the controller, which then signals the clutch engagement after gearshift operation.
[00028] Fig. 5 illustrates a sectional view of the clutch actuation sensor connected to the actuator plunger. The clutch actuation sensor 111 is directly connected to the actuator plunger 115 including an extended portion 116. The clutch actuation sensor 111 according to an embodiment is a linear movement sensor that detects any linear movement of the part attached therewith. Further, according to an embodiment of the present invention, the clutch actuation sensor 111 includes a connecting member 111a at one end. The connecting member 111a enables connecting between the clutch actuation sensor 111 and the actuator plunger 115. The other end 111b of the clutch actuation sensor 111 is configured to get connected to the controller.
[00029] Furthermore, according to an embodiment of the present invention, the connecting member 111a is a retractable structure. For example, the connecting member 111a includes a preloaded elastic member installed within the connecting member 111a.
[00030] Hence, according to an embodiment, the clutch actuation sensor 111 directly senses the linear movement of the actuator plunger 115. The clutch actuation sensor 111 according to an embodiment does not include any connection either directly or indirectly with the caged ball-holding member 113 and the worm wheel 110. Hence, the clutch actuation sensor 111 is independent of any other parts present around. The elastic member situated inside the connecting member enables linear motion of the connecting member with respect to the linear motion of the actuator plunger 115.
[00031] Therefore, any error occurring in the functionality of the worm wheel 110 or the holding member 113 does not affect the working of the clutch actuation sensor 111. Therefore, the clutch actuation sensor 111 carries out more accurate detection of the linear movement of the actuator plunger 115. Hence, a more accurate input is given to the controller, which in turn decides accurate time to shift gears automatically. Thereby, resulting in improved drive feel at the user end.
[00032] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein.
,CLAIMS:I/We claim:
1. An internal combustion engine assembly (100) comprising:
an electrically operated clutch (139) including a clutch actuation motor (105) mounted on an external surface of a clutch cover (102); and
a power transmission mechanism (200) for converting rotational driving force of said clutch actuation motor (105) into linear motion, said power transmission mechanism (200) comprises of a worm wheel (110), an actuator plunger (115), a set of caged ramp balls (114) capable of rotating between said worm wheel (110) and said actuator plunger (115) to transfer said rotational driving force from said worm wheel (110) into said linear motion of said actuator plunger (115),
wherein, a clutch actuation sensor (111) for detecting actuation of the clutch (139) is provided, said clutch actuation sensor (111) is directly connected to at least a portion of said actuator plunger (115) for detecting linear movement of the actuator plunger (115).
2. The internal combustion engine assembly (100) as claimed in claim 1, wherein said actuator plunger (115) includes an extended portion (116) capable of receiving said clutch actuation sensor (111).
3. The internal combustion engine assembly (100) as claimed in claim 1, wherein said clutch actuation sensor (111) includes a connecting member (111a) at one end (111aa), said connecting member (111a) enables connection between said clutch actuation sensor (111) and said actuator plunger (115).
4. The internal combustion engine assembly (100) as claimed in claim 1, wherein said clutch actuation sensor (111) includes other end (111b) configured to be connected to a controller.
5. The internal combustion engine assembly (100) as claimed in claim 1, wherein said clutch actuation sensor (111) is a linear movement sensor capable of detecting any linear movement.
6. The internal combustion engine assembly (100) as claimed in claim 1, wherein said actuator plunger (115) and a return spring (124) are housed within a clutch cover (102) covering said engine (100).
7. The internal combustion engine assembly (100) as claimed in claim 1 or claim 6, wherein said actuator plunger (115) and said return spring (124) are operatively engaged through a rack and pinion arrangement.
8. The internal combustion engine assembly (100) as claimed in claim 1 or claim 6, wherein said return spring (124) comprises a clutch release shaft (125) to bring the return spring (124) to its original position after the withdrawal of manual force.