Motorcycle Engine

Abstract

A motorcycle engine comprises an oil pump and a cam chest cover. The cam chest cover comprises a crankshaft pinion bearing and a camshaft bearing. The engine is configured and adapted such that the oil pump supplies pressurized oil to the crankshaft pinion bearing and the camshaft bearing. The engine is also adapted to receive both a crankshaft position sensor and, alternatively, a camshaft position sensor. The cam chest cover also comprises a pressure relief valve that diverts excess oil into a scavenge oil passageway that leads out of the engine. Still further, the engine comprises at least one check valve that allows air to pass from the wheel chest to the cam chest, but not the reverse.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to motorcycle engines. More particularly, one aspect of the invention pertains to a system for lubricating a motorcycle engine during operation. Another aspect of the invention pertains to a cam cover that is configured to allow a cam position sensor to be mounted to the exterior side of the cam cover. The engine preferably comprises only one camshaft, which is preferably driven directly via intermeshed gears.

2. General Background

There are two main types of motorcycle lubrication systems, namely, wet sump and dry sump lubrication systems. In a wet sump lubrication system, the oil reservoir is contained within the engine case. In contrast, in a dry sump lubrication system, an external oil reservoir is provided and excess oil is scavenged from the engine case. An example of a dry sump motorcycle engine lubrication system is disclosed in U.S. Pat. No. 6,116,205, issued on Sep. 12, 2000. In that lubrication system, a scavenge pump and a supply pressure pump are located within the cam chest of the engine. The single scavenge pump is configured to scavenge oil from the cam chest and from the crank/wheel chest independently of each other such that when one runs dry, oil continues to be scavenged from the other. The scavenge pump pumps the scavenged oil to an external reservoir tank. The supply pressure pump draws oil in from the reservoir tank and delivers pressurized oil to the crank pin and lifters. Additional oil passages allow the pressurized oil to pass from the lifters up to the upper end of the engine and through the crankshaft to the piston rod and piston/wrist pin. A pressure relief valve diverts oil from the high pressure side of the supply pressure pump to the low pressure side of the supply pressure pump when the oil pressure exceeds a particular pressure. The camshaft bearings are not pressure lubricated and instead are splash lubricated.

SUMMARY OF THE INVENTION

In one aspect of the invention, a motorcycle engine comprises a crankshaft pinion bearing, a camshaft bearing, and an oil pump. The engine is configured and adapted such that the oil pump supplies pressurized oil to the crankshaft pinion bearing and the camshaft bearing.

In another aspect of the invention, a motorcycle engine comprises a cam chest cover. The cam chest cover comprises an oil passageway and a pressure relief valve. The pressure relief valve is configured and adapted to regulate oil pressure within the oil passageway.

In yet another aspect of the invention, a motorcycle engine comprises a camshaft and a cam chest cover. The cam chest cover comprises a camshaft bearing and a crankshaft pinion bearing. The camshaft is supported by the camshaft bearing for rotation relative to the cam chest cover. The crankshaft pinion is supported by the crankshaft pinion bearing for rotation relative to the cam chest cover. The cam chest cover comprises an opening that is configured such that an ignition timing unit can be operatively attached to the camshaft from the exterior side of the cam chest cover.

In still another aspect of the invention, a motorcycle engine comprises a pressurized oil passageway, a scavenged oil passageway, and a pressure relief valve. The scavenged oil passageway is configured to route oil out of the engine. The pressure relief valve is configured and adapted to regulate oil pressure within the pressurized oil passageway and to divert oil from the pressurized oil passageway to the scavenged oil passageway.

Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawing, which is incorporated in and forms a part of the specification, illustrate the preferred embodiment of the present invention and together with the description, serves to explain the principles of the invention.

The FIGURE depicts a motorcycle engine schematically.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A lubrication system in accordance with the present invention is shown schematically in the attached FIGURE. The lubrication comprises two separate scavenge pumps and a pressure pump. The pumps are preferably each a gear pump and are preferably attached to the exterior of the engine case beneath the cam chest. Each of the pumps draws oil in and out through openings provided in the bottom wall of the cam chest. As illustrated in the drawing, oil scavenged from the cam chest passes through the cam chest wall to the cam chest scavenge pump 20. The cam chest scavenge pump 20 then forces the scavenged oil through a scavenged oil passageway 22 that extends through the cam chest wall, and then through the cam chest cover. The scavenged oil passageway 22 leads to a fitting and then to an external line that is operatively connected to an external oil reservoir. In a similar manner, oil scavenged from the wheel chest passes through the bottom wall of the cam chest to the wheel chest scavenge pump 24 where it is thereafter forced back through the cam chest wall and into the scavenged oil passageway 22.

Oil from the external oil reservoir is sucked into the engine through a separate external line that attaches to a fitting on the cam chest cover. A separate passageway 26 in the cam chest cover then delivers that oil to the pressure pump 28 through the bottom wall of the cam chest. The pressure pump 28 then forces oil into a passageway 30 that extends through the cam chest bottom wall, then through a fitting that that is operatively connected to another external line, which routes the pressurized oil to the external oil filter. From the oil filter, oil passes along another passageway 32 that extends through yet another external line and is operatively connected to the cam chest cover. That passageway 32 leads to a pressure regulator that is formed in the cam chest cover. The pressure regulator is configured to divert oil to the scavenged oil passageway 22 to maintain the oil pressure at particular pressure. Oil that is not diverted then passes through another passageway 34 formed in the cam chest cover that delivers the pressurized oil to a crankshaft pinion bearing, and then to a camshaft bearing, and ultimately to the top end of the engine through the lifter block. Some of the pressurized oil is diverted from the crankshaft pinion bearing through a passageway in the crankshaft that extends to the piston rod bearings. Most of that oil then passes up through passageways formed in the piston rods that lead to the piston wrist pins.

Gravity carries oil down from the upper end of the engine to the cam chest, where it once again is scavenged by the cam chest scavenge pump 20. Likewise, oil dripping from the piston pins and piston rods is scavenged by the wheel chest scavenge pump 24 as discussed above. By positioning the various oil pumps on the exterior of the engine case, the oil pumps can be serviced without removing the cam chest cover. It should also be appreciated that because the pressure regulator bleeds excess oil directly into the scavenge passageway 22, the pressure pump is always supplied with only cool oil from the oil reservoir, and the flow rate of oil through the oil filter is maximized. In other words, unlike the lubrication system disclosed in the patent discussed above, oil will not circulate within the pressure pump when the pressure pump is operating faster than needed. Additionally, the excess oil is ported directly back to the external reservoir, which maximizes oil cooling.

As depicted in the drawing FIGURE, the cam chest cover comprises the camshaft bearing and the crankshaft pinion bearing. The cam chest cover also comprises an opening that is configured such that an ignition timing unit can be operatively attached to the camshaft from the exterior side of the cam chest cover. The opening preferably has a recess that is configured to at least partially receive the ignition timing unit. If such an ignition timing unit is not needed, a cover plate can instead be mounted to the cam chest cover to thereby cover the opening. The engine further comprises an externally accessible fitting that is adapted to receive a crankshaft position sensor for an ignition timing unit that is adapted to operate off of a crankshaft position sensor rather than a camshaft position sensor. Thus, the engine can easily be adapted to operate via different alternative styles of ignition timing systems, without removal of the cam chest cover.

The engine also preferably comprises a pair of check valves that allow air to pass from the crank/wheel chest into the cam chest, but not the reverse. The check valves are preferably reed valves and act to reduce the pressure in the crank/wheel chest. The reduce pressure in the crank/wheel chest facilitates proper piston ring sealing.

In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained.

The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.

As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.

Claims

1. A motorcycle engine comprising a crankshaft pinion bearing, a camshaft bearing, and an oil pump, the engine being configured and adapted such that the oil pump supplies pressurized oil to the crankshaft pinion bearing and the camshaft bearing.

2. A motorcycle engine in accordance with claim 1 wherein the engine comprises a cam chest cover and the cam chest cover comprises the camshaft bearing and the crankshaft pinion bearing.

3. A motorcycle engine in accordance with claim 1 wherein the engine comprises a pressure relief valve that diverts oil from a pressurized oil passageway to a scavenged oil passageway, the scavenged oil passageway leading out of the engine and being downstream of any scavenge pump.

4. A motorcycle engine in accordance with claim 3 wherein the engine is configured and adapted to divert oil from through a filter located downstream of the pressure pump and upstream of the pressure relief valve.

5. A motorcycle engine in accordance with claim 1 wherein the engine comprises a wheel chest, a cam chest, and two scavenge pumps, one of the scavenge pumps is operatively connected to the wheel chest to scavenge oil therefrom, and the other of the scavenge pumps is operatively connected to the cam chest to scavenge oil therefrom.

6. A motorcycle engine comprising a cam chest cover, the cam chest cover comprising an oil passageway and a pressure relief valve, the pressure relief valve being configured and adapted to regulate oil pressure within the oil passageway.

7. A motorcycle engine in accordance with claim 6 wherein the cam chest cover comprises a camshaft bearing and crankshaft pinion bearing, and the oil passageway is configured to supply pressurized oil the camshaft bearing and to the crankshaft pinion bearing.

8. A motorcycle engine comprising a camshaft and a cam chest cover, the cam chest cover comprising a camshaft bearing and a crankshaft pinion bearing, the camshaft being supported by the camshaft bearing for rotation relative to the cam chest cover, the crankshaft pinion being supported by the crankshaft pinion bearing for rotation relative to the cam chest cover, the cam chest cover comprising an opening configured such that an ignition timing unit can be operatively attached to the camshaft from the exterior side of the cam chest cover.

9. A motorcycle engine in accordance with claim 7 wherein the engine comprises an externally accessible fitting that is adapted and configured to receive a crankshaft position sensor.

10. A motorcycle engine comprising a pressurized oil passageway, a scavenged oil passageway, and a pressure relief valve, the scavenged oil passageway being configured to route oil out of the engine, the pressure relief valve being configured and adapted to regulate oil pressure within the pressurized oil passageway and to divert oil from the pressurized oil passageway to the scavenged oil passageway.

11. A motorcycle engine in accordance with claim 10 wherein the engine comprises at least one scavenge pump, the scavenge pump being adapted and configured to deliver oil to the scavenged oil passageway.

12. A motorcycle engine in accordance with claim 11 wherein the engine comprises a wheel chest, a cam chest, and at least one check valve, the check valve being adapted and configured to allow air to pass from the wheel chest to the cam chest and to prevent air from passing from the cam chest to the wheel chest.