Transmission system for an internal combustion engine

Field of the invention

The subject matter described herein in general relates to an automatic manual transmission system, and in particular relates to an automatic manual transmission system for a four stroke internal combustion engine.

Description of the prior art

Straddle type vehicles such as motorcycles have a transmission system to transmit power generated from engine to the wheel. The transmission system includes a shift mechanism having a main shaft, a drive shaft, and multiple step speed change gear and a clutch mechanism that interrupts the transmission while operating the speed change gear. More broadly, the manual transmissions comprises a system of interlocking gears, such that by operating a gear shift 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 from lower to higher or vice versa, 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. However, this manual transmission requires additional movement and continuous attention by the user regarding the speed of the motorcycle. Consequently semi-automatic and automatic transmission systems came into the art for ease of operation of gearshift and clutch actuation. In automatic transmission system (AMT) two actuating motors are used for actuating gearshift and clutch operation. However, heavy system alterations are required for adopting the motors into the vehicle, most notably crankcase alterations, etc. Hence, for same engine design and capacity, a totally new engine crankcase construction is required. This in effect increases variation and complicates overall design standardsation of concerned components to accommodate the motors. Hence there needs to be design change that accommodates both the manual transmission system as well as AMT without any major variation in engine assembly configuration in terms size and weight Hence the main objective of the present invention is to provide an arrangement for AMT system that accommodates the two actuating motors in the vehicle system with minimum engine assembly design alterations.

Brief description of the invention

Accordingly one embodiment of the present invention provides a transmission system operating between the engine and a driven shaft, the transmission includes a multi-step shift mechanism wherein a gear shift actuator is mounted on the inner portion of the clutch cover and is perpendicular to the crankcase as viewed from the side. A clutch mechanism operates between the engine and the transmission wherein a clutch actuator is mounted on the inner portion of clutch cover that is orthogonal to the said gearshift actuator. Thus, both the actuators are located on the inner portion of the clutch cover and are perpendicular to each other.

Brief description of the drawings

Figure 1 illustrates a typical four stroke internal combustion engine.

Figure 2 illustrates the clutch and gear actuation mounting according to the present invention.

Figure 3 illustrates the gear actuation mounting and mechanism according to the present invention.

Figure 4 illustrates the clutch actuation mounting and mechanism according to the present invention.

Detailed description of the invention

A selected illustrative embodiment of the present invention will be now described with respect to the accompanying figures 1,2,3 and 4. The core part of a normal four stroke engine 200 is illustrated in figure 1. It is characterized by a cylinder 201 with the piston 202 moving up and down inside the cylinder 201. Some of the key engine parts along with their functions are spark plug (nor shown in the figure) which supplies the spark which ignites the air/fuel mixture so that combustion could occur; valves 203 wherein the intake and exhaust valves open at the proper time to let in air and fuel to let out exhaust; a piston 202 which is a cylindrical piece of metal that moves up and down inside the cylinder 201; piston rings 204 that provide a sliding seal between the outer edge of the piston 202 and the inner edge of the cylinder 201; connecting rod 205 which connects the piston 202 to the crankshaft 206; crankshaft 206 which turns the piston's up and down motion into circular motion; a sump 207 which surrounds the crankshaft 206 and contains oil which collects in the bottom of the sump 207; etc. The crankcase 300 has a structure in which the half cases are integrally connected to each other. The halves cases are formed by dividing the crankcase 300 into right and left portions. A crankshaft 206 is rotatable bearing supported on both the said halves. A connecting rod 205 is rotatably attached to a crankpin of the crankshaft 206 via a bearing located at the large-end thereof. A piston 202 is pivotally attached to the small-end of the connecting rod 205 via a piston pin. In this embodiment, there is provided one piston 202 and the engine 200 of the present invention is a single cylinder 4-cycle engine. Transmission system comprises a clutch 301, a drive shaft, a driven shaft; multi-step gear housed on one half of the crankcase and is covered by a clutch cover (not shown in figure).

Accordingly one embodiment of the present invention provides a transmission system operating between the engine 200 and a driven shaft, the transmission includes a multi-step shift mechanism wherein a gear shift actuator 305 is mounted on the inner portion of the clutch cover and is perpendicular to the crankcase 300 as viewed from the side. A clutch mechanism operates between the engine 200 and the transmission wherein a clutch actuator 306 is mounted on the inner portion of clutch cover that is orthogonal to the said gearshift actuator 305. Thus, both the actuators 305,306 are located on the inner portion of the clutch cover and are perpendicular to each other. The gear shift actuator 305 includes a gear shift motor 307, a shift control unit, a plurality of reduction gears 308 which reduces the rotation of the shift motor 307, a power transmission mechanism 309 which transmits the rotation driving force of the shift motor 307 and a shift position detector which detects the position of the gear. The clutch actuator mechanism includes an actuator motor 310, a plurality of reduction gears 311 that reduces the rotation of the clutch actuator motor 310, a power transmission mechanism 312 that transmits the rotation driving force of the clutch actuator motor 310 and a clutch actuation detector 313 that detects the actuation of the clutch.

In the present embodiment, an automatic transmission control unit is configured so as to operate the clutch mechanism and the gearshift mechanism in a synchronized manner.

The power transmission 309 that transmits the rotation driving force of the shift motor to gear shift is performed by ratchet and pawl gear mechanism through a set of reduction gears 308 and the power transmission that transmits the rotation driving force of the clutch actuator motor 310 on the clutch actuator is performed by a worm gear mechanism 312.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Claims We claim:

1. A motorcycle comprising

a head pipe;

a body frame including a main frame extending rearward from the head pipe;

an engine along with crankcase supported on the body frame;

a transmission operating; between the engine and a driven shaft, the transmission including a multi-step shift mechanism wherein a gear shift actuator is mounted on the crankcase and crosses the engine crankcase as viewed from the side;

a clutch mechanism operating between the engine and the transmission

wherein a clutch actuator is mounted on the clutch cover which is orthogonal to the said gear shift actuator.

2. The motorcycle as claimed in claim 1, wherein the gear shift actuator includes a gear shift motor, a shift control unit, a plurality of reduction gears which reduces the rotation of the shift motor, a power transmission mechanism which transmits the rotation driving force of the shift motor and a shift position detector which detects the position of the gear.

3. The motorcycle as claimed in claim 1, wherein the clutch actuator mechanism includes an actuator motor, a plurality of reduction gears which reduces the rotation of the clutch actuator motor, a power transmission mechanism which transmits the rotation driving force of the clutch actuator motor and a clutch actuation detector which detects the actuation of the clutch.

4. The motorcycle as claimed in claim 1, wherein the clutch mechanism includes a plurality of hydraulically actuated friction clutch plates.

5. The motorcycle a claimed in claim 1, wherein the gear shift mechanism includes a multi-step gear mechanism.

6. The motorcycle as claimed in claim 2, wherein an automatic transmission control unit is configured so as to operate the clutch mechanism and the gearshift mechanism in a synchronized manner.

7. The motorcycle as claimed in claim 2, power transmission that transmits the rotation driving force of the shift motor to gear shift is performed by ratchet and pawl gear mechanism through a set of reduction gears.

8. The motorcycle as claimed in claim 3, wherein the power transmission that transmits the rotation driving force of the clutch actuator motor on the clutch actuator is performed by a worm gear mechanism.