Lubrication system for two wheeler engines

Field of the invention

The present invention relates to a "Lubricating system for two wheeler engines", and more particularly to a new type of improved lubrication system which is accommodated on the right hand side of the engine crankcase, for providing effective lubrication through shortest possible circuits and thereby minimizing the complexity in crankcase Left hand side and transmission covers, as well as eliminating the joint leakages at crankcases and transmission covers.

Background of the invention

Internal combustion engines requires a lubricating system for providing lubrication to various relatively moving parts of engine in order to provide smooth running and for avoiding any wear and tear damage to the engine. The lubricating system must be operated efficiently to increase the life of the engine and its components.

In known type of lubrication system arrangements, the lubricating pump and the filter are positioned at a great distance apart from one another. For example, the oil pump may be positioned in the crankcase of the engine at one side thereof, while the sump is positioned at a distance off the pump. As a result relatively longer lubrication circuit is present through the engine right from the pump to the filter. Providing this circuit complicates the construction of the engine. In addition, the length of the passages or channels contributes to oil pressure losses. Moreover, this type of construction always gives a probability of oil leakage through joint between the components. Accordingly the first objective of the invention is to provide an improved lubricating system for an engine having effective lubrication through shortest possible circuits and thereby minimizing the complexity in crankcase and transmission covers.

Another objective of the present invention is to provide a lubrication circuit wherein the oil pressure loss is minimal.

Another objective of the present invention is to simplify the construction and manufacturing the transmission covers and lubrication circuit.

Summary of the invention

The present invention provides an improved lubrication structure for an engine, in which the improved lubrication structure is provided to solve the foregoing problems. The engine, which utilizes the improved lubrication, includes a crankcase having an oil pan at its lower position, a crankshaft which is rotatable supported in the crankcase, and a rotating oil pump member which rotates in conjunction with the crankshaft and which pumps oil in the oil pan located at the lower position of the crankcase. The engine further includes an oil receiver for receiving oil that has been pumped up via the rotary member, and an oil path for circulating oil from the oil receiver to selected portions of the crankcase for lubrication. This lubrication system is located on the right hand side of the crankcase and thereby facilitating the assembling and maintenance of the lubrication system. In other words, the present invention relates to an improved lubrication system for a vehicle engine comprising an oil circuit having oil supply passages and branch passages formed integrally in the wall surface of a crankcase to supply oil to various engine parts, an oil pump housed in the crankcase discharging the oil in response to the rotation of a crankshaft of the said engine, wherein the oil circuit is housed at the right hand side of the crankcase of the engine. Moreover, the oil pump comprises a rotor, an oil inlet tube and an oil outlet tube that are assembled on the right-hand side of the crankcase. The pressurised oil is directly fed from the sump to circuit, all located in the right hand side, by the pump, and therefore forming an essential shortest lubricating circuit or path for oil pump outlet to piston lubrication and crankshaft lubrication. This effectively reduces the dead volumes involved in the crankcase cover that are present for facilitating the oil transfer from right side crankcase to left side crankcase and thus could transfer the oil from the sump to the crankshaft in much smaller time when compared with others.

Brief description of the drawings

Figure 1 shows a representative view of a scooter type motorcycle according to the present invention.

Figure 2 shows the cross sectional view of the engine assembly having embodiments according to the present invention.

Figure 3 shows the sectional view of the lubrication assembly 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.

Figure 1 is a side plan view of a scooter type motorcycle provided with an engine 102. This engine is provided with an Improved lubrication structure according to an embodiment of the present invention. Any known scooter type motorcycle, as illustrated in Figure 1, can be divided into three major portions, the front portion, the middle portion and the rear/tail portion.

The front portion comprises of the head tube, the handle bar 105, the front suspension 103, the front wheel with necessary brakes and the body panels 109;

the middle portion comprises of the floor board, the seat support 106, the fuel tank, the battery, the utility box etc;

and the rear/tail portion comprises of the engine support, the riders seat 106, the rear shock absorber 104, rear fender and the back wheel with suspensions.

In assembling such a vehicle, especially the body covers 109, there are many sub assemblies and these are independently mounted onto the frame 101 at different locations. The body covers 109 are mounted to the frame 101 using brackets.

Scooter-type vehicles, or scooters, include a frame assembly 101, which usually supports the body of a scooter, along with front and rear wheels. A frame assembly for a scooter-type vehicle comprises of at least one front wheel, at least one rear wheel and a vehicle body.

Typically, a frame structure 101 for a scooter type motorcycle comprises a main frame and may also have a sub-frame. The sub-frame is attached to the main frame using appropriate fastening members. All the other components such as the body panels 109, the engine 102, the electrical units are mounted on the main frame and the sub frame either directly or by means of brackets and fastening members.

The frame assembly includes a head tube, which supports a front wheel suspension assembly 103 of the vehicle. An upper frame extends from the head tube to a rearward end of the vehicle body. A swing arm 104 is pivotally supported by the upper frame and supports a rear wheel of the vehicle. The frame assembly may include a lower frame removeably coupled to the upper frame and defining a space 107 there between.

The sub-frame preferably supports at least one component of the scooter-type vehicle in the space, such as a fuel tank, for example.

Typically, front 103 and rear 104 suspension assemblies are operatively positioned between the front and rear wheels and the frame assembly. The front suspension assembly 103 commonly is a telescopic fork arrangement, while the rear suspension assembly 104 is a swing type arrangement. In a scooter, the rear suspension swing arm typically supports a power unit 102, which is configured to drive the rear wheel of the scooter.

The power unit 102, is coupled along with a transmission assembly 108, such as a drive shaft, drive belt, or chain and sprocket assembly.

The frame assembly 101 of a scooter-type vehicle is an elongated structure, which typically extends from a forward end to a rearward end of the scooter, A scooter frame assembly generally is convex in shape, as viewed from a side elevational view. 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.

In Figure 2, the principal portion of the engine of the present invention is shown in cross-sectional view. As shown in this figure, the engine includes a crankcase 201, a cylinder block 202 connected to the crankcase 201, a cylinder head 203 to be connected to the cylinder block 202 and a cylinder head cover. These are clamped and fixed together via stud bolts and the like, thereby constituting the main structure of the engine 102.

The crankcase has a structure in which the half cases 204 & 205 are integrally connected to each other. The halves cases and are formed by dividing the crankcase into right 205 and left portions 204. In the crankcase, formed of the combined half cases and, a crankshaft is rotatable bearing 206 supported. A connecting rod 207 is rotatable attached to a crankpin of the crankshaft 208 via a bearing located at the large-end thereof. A piston 209 is pivotally attached to the small-end of the connecting rod 207 via a piston pin. In this embodiment, there is provided one piston and the engine of the present invention is a single cylinder 4-cycle engine.

In the transmission portion of the power unit, a variable speed ratio V-belt drive 210 extends rearward from about the crankshaft 208. A driving pulley 211 is fixed to the crankshaft. The driving pulley includes a fixed pulley half 212 which is caused to rotate with the output shaft. The fixed pulley half is disk shaped with a conical pulley surface. On the outer side of the pulley half is a fan 213 to cool the system with air drawn in through a passageway formed in the case 201. To provide lubrication to the engine assembly 102, which must cycle back and forth under load during driving of the vehicle, a sump 7 for lubrication oil is provided.

The engine of this embodiment generally includes the structure described above. However, the engine further includes an inventive lubrication structure. Hereinafter, this lubrication structure will be described with respect to Figure 3.

Figure 3 describes the sectional view of the present invention. The present invention relates to an engine-lubricating device including an oil pump 303 that is housed in crankcase 201 and pump oil in response to the rotation of a crankshaft 208. The invention provides an engine lubricating system in which the oil pump 303 is assembled on the right side of the crankcase 205, and thereby facilitating easy assembling and maintenance of the lubricating system.

The crankcase 201 constitutes crankcase body 205 on the right hand side and crankcase cover that is provided on the right side of the crankcase body. The crankcase right hand side has a lubricating oil sump 307 incorporative formed at the bottom of the crankcase for collecting the lubricating oil. The oil sump 307 is formed just below the pump 303 in the cover side, such a way that the oil suction is directly from it.

When assembling the oil pump 303 into an engine, components constituting the oil pump 303, such as a oil inlet tube 304, oil outlet tube 301 also have to be incorporated in the right hand side of the crankcase 205. The oil sump 307 and the oil drain are provided in the bottom of the crankcase of the engine along with an oil drain cap 306.

The lubricating oil in the oil sump 307 is sucked up by the pump 303 and led out to an oil passage 308 for feeding pressurized oil formed within the wall of the right side of the casing and leading to various parts such as for piston lubrication 309. The lubricating oil is delivered from the oil pump 303 to cylinder block 202 through passages in right hand side of the crankcase 205-wall surface. An oil filter 305 is formed within the right side of the casing. This new type of lubrication system that is accommodated on the right hand side of the engine crankcase 205 provides effective lubrication through shortest possible circuits 308. This helps in effective lubrication through shortest possible circuits 308 for pump outlet to piston lubrication and crankshaft lubrication and thereby minimizing the complexity in crankcase 201 and transmission covers. Also joint leakages at crankcase and transmission covers of the engine are eliminated. This also minimizes the dead volumes involved in the crankcase cover that are present for facilitating the oil transfer from right side crankcase to left side crankcase and thus could transfer the oil from the sump to the crankshaft in much smaller time when compared with others.

Figure numbers associated with the invention
101. Frame assembly 108. Transmission assembly
102. Engine/ Power unit 109. Body panels\covers
103. Front wheel suspension 201. Crankcase
104. Swing arm 202. Cylinder block
105. Handle bar assembly 203. Cylinder head
106. Seat 204. Left hand side crankcase
107. Space 205. Right hand side crankcase
206. Crankshaft bearing 302. Oil level gauge
207. Connecting rod 303. Oil pump
208. Crankshaft 304. Oil pump inlet tube
209. Piston 305. Oil filter
210. V- belt 306. Oil drain cap
211. Drive pulley 307. Oil sump
114. Fixed pulley 308. Oil circuit for crankshaft
213. Fan 309. Oil jet for piston lubrication 301 .Oil pump outlet tube

1. A lubrication system for a vehicle engine comprising:

an oil circuit 308 having oil supply passages and branch passages formed integrally in the wall surface of right hand side crankcase 205 to supply oil to various engine parts;

an oil pump 303 housed in the right hand side crankcase 205 discharging the oil in response to the rotation of a crankshaft 208 of the said engine 102;

an oil sump 307 located below the oil pump 303 in the crankcase 201;

wherein the oil pump transfers the oil directly from oil sump to oil circuit forming a shortest possible path for lubricating oil to transfer and thus effectively reduce the dead volumes involved in transfer of oil from one side to other side of the crankcase.

2. The oil pump as claimed in claim 1, wherein the said oil pump 303 comprising a rotor, an oil inlet tube 304, an oil outlet tube 301 are assembled on the right hand side of the crankcase 205.