HYDRO-LOCK

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to United States Patent Application

Serial Number 61/683, 062, filed August 14, 2012 in the name of Griffin et al, and entitled RADIAL ENGINE WITH PISTON CONFIGURATION TO PREVENT HYDRO-LOCK, the entire contents of which are incorporated herein by reference for all purposes.

FIELD

[0002] The present disclosure relates generally to a radial engine. More particularly, the present disclosure relates generally to an improved radial engine capable of use as a power source for a highly efficient and capable relatively very long-running electric generator.

BACKGROUND

[0003] Wet or dry sump oil scavenging in a radial engine is an incomplete process after the engine is shutdown. After shutdown of the engine for a period of time, an undesired quantity of oil will be left over in the bottom of a crankcase of the engine. Conventional radial engines are prone to oil migration into the lowest oriented combustion chambers (i.e., those combustion chambers located closest to the 6 o'clock position) as a result of movement of the oil, due to gravitational forces, past seals or compression rings located on a piston. The oil migration into the cylinder may be problematic because oil is a relatively incompressive liquid and when located in a combustion chamber where the fluids of combustion (air and fuel vapor) is normally compressed leads to a problem commonly known as "liquid lock" or "hydrolock". This is a shorthand reference for hydrostatic lock which occurs when a volume of liquid greater than the volume of the cylinder at its minimum (i.e., at the end of the piston's stroke) enters the cylinder. Since most common liquids (including oil) are incompressible, the piston cannot complete its travel and either the engine must stop rotating or a mechanical failure must occur ultimately resulting in engine damage upon starting of the engine during a hydrolock condition. It is known to slowly hand crank the engine prior to start up to purge the liquid form the cylinder and thereby eliminate the hydrolock condition and avoid damage to the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 illustrates a cross-section of a radial engine.

[0005] FIG. 2 is a side-view of the radial engine of FIG. 1.

[0006] FIG. 3 is a side view of a piston of the radial engine of Figure 1.

[0007] FIG. 4 is a further side-view of a portion of the piston of FIG. 3.

[0008] FIG. 5 is another side-view of a portion of the piston of FIG. 4.

[0009] FIG. 6 is a different orientation side-view of a portion of the piston of FIG. 4.

[0010] FIG. 7 is another side-view of a portion of the piston of FIG. 5.

[0011] FIG. 8 is a cross-section of a radial engine according to an exemplary embodiment of the present disclosure.

[0012] FIG. 9 is a side-view of the radial engine of FIG. 8.

[0013] FIG. 10 is a side view of a piston of the radial engine of Figure 8.

[0014] FIG. 11 is a side-view of the piston of FIG. 10.

[0015] FIG. 12 is a side-view of a portion of the piston of FIG. 11.

[0016] FIG. 13 is another side-view of a portion of the piston of FIG. 10. [0017] FIG. 14 is a different orientation side-view of a portion of the piston of FIG 12.

DETAILED DESCRIPTION

[0018] With particular reference to Figures 1 and 2, an exemplary radial engine 10 is shown similar to the radial engine disclosed in United States patent application number 12/503,066, filed July 4, 2009, in the name of Kealy et al. and entitled PORTABLE ENERGY GENERATION SYSTEMS, the entire contents of which are incorporated herein by reference. The radial engine 10 may be a reciprocating internal combustion engine that may include a connecting rod 20 and a crank pin 30. The crank pin 30 may be mechanically attached to the center of the connecting rod 20 and may be aligned parallel to a main crankshaft (not shown). The radial engine may further include a plurality of cylinders 40 located and extending radially outward from the connecting rod 20 and wherein the cylinders 40 are generally coplanar. While the radial engine 10 may include between three (3) and nine (9) cylinders 40; in the exemplary embodiment of the present disclosure the radial engine 10 includes nine (9) cylinders 40 as best shown in Figure 1 as a non-limiting example.

[0019] A piston 90 may be associated with each cylinder 40 to form a piston-cylinder pair. Accordingly, the radial engine 10 includes nine (9) piston- cylinder pairs. Each piston 90 may include a pin 120 as an attachment mechanism for securing the piston 90 to the connecting rod 20. Particularly, the pin 120 may secure the piston 90 to a respective piston rod (not shown). The piston rod may be attached directly to a connecting rod 20, and the connecting rod 20 may be attached to the crankshaft (not shown). When piston 90 moves downward in response to a combustion event, the connecting rod 20 also moves because each piston 90 drives its associated connecting rod 20. Each piston 90 may include a top portion or crown 100 and a bottom portion or skirt 105. Further included with each piston 90 and cylinder 40 are an intake valve 60 and an exhaust valve 70. The intake valve 60 is where an air and fuel vapor mixture are taken into and fill the cylinder 40 and, conversely, the exhaust valve 70 is where the results of the combustion (i.e., exhaust) departs the cylinder 40. Each piston 90 may further include a sealing ring 130 that may be situated near the crown 100 of the piston 90. Cylinder 40 and each associated piston 90 define a combustion chamber 135 which expands and contracts as the piston 90 operates via upward and downward movements in the cylinder 40.

[0020] Each Piston 90 may be attached to the connecting rod 20 by a piston rod (not shown). As connecting rod 20 revolves, the piston 90 starts at the top of cylinder 40 and the combustion chamber is its smallest, the intake valve 60 opens, and the piston 90 moves down to draw in air and fuel vapor mixture into the cylinder 40 to fill the combustion chamber 135. This is understood as the intake stroke. Next, piston 90 moves back upward in the cylinder 40 to compress the mixture of air and fuel vapor. This is understood as the compression stroke. As the piston 90 is near the top of its stroke, a spark may occur which results in ignition of the fuel-air mixture. Alternatively, the mixture may be ignited via compression ignition wherein the fuel vapor will automatically ignite without a spark. Regardless, the mixture in the combustion chamber 135 in cylinder 40 combusts and the result is that piston 90 is driven downward in the cylinder 40 as the combustion chamber 135 expands due to the energy of combustion. Once piston 90 reaches the bottom of its stroke, exhaust valve 70 opens and the exhaust may leave cylinder 40.

[0021] Upon shut down of engine 10, oil accumulation may occur. For example, residual oil may flow into the cylinders 40. Additionally, oil may migrate into the combustion chamber 135 of the lowest oriented cylinder piston pairs as a result of gravitational forces causing movement of the oil past sealing ring 130 of piston 90.

[0022] Referring now in particular to Figure 3, the crown 100 of the piston 90 of the engine of Figure 1 is illustrated in further detail. Operationally, oil may be pumped into connecting rod 20 to lubricate the connecting rods 20 and their bearings and other components of the engine 10. During shutdown of the engine 10, oil may flow in a downward direction along the inner walls of the cylinder 40. As oil travels due to gravity, it may migrate via bores 160 situated in crown 100 through the piston 90, and it may then migrate around sealing ring 130 resulting in some oil being captured and retained in the back of the crown 100. The captured oil volume is identified and labeled with V. Oil not retained in retention chamber 140 may continue to flow or migrate onward and out of piston 90 into the bottom of the combustion chamber 135, where it will accumulate if the valves are closed.

[0023] This issue may be problematic because oil inside combustion chamber 135 may lead to the hydrolock condition, which ultimately may result in very serious damage to the engine 10 upon starting. Another potential problem may also occur upon startup. Even if there is not sufficient oil in the cylinder 40 to cause a hydrolock condition, with even a relatively small but still excess quantity of oil present in the combustion chamber 135, it may result in unacceptable levels of hydrocarbon emissions during startup. Such excess oil condition may even be manifested as oil droplets expelled in the exhaust from the chamber 135 which may be conveyed downstream to other components such as exhaust gas recirculation valves, turbochargers and exhaust silencers (not shown) and cause fouling and damage therein. Additionally, spark plugs may become contaminated and misfire. A weak spark cannot properly ignite the fuel and air mixture, causing the mixture to be incompletely burned or not ignited at all.

[0024] Referring now to Figures 8 through 14, a radial engine 200 according to an exemplary embodiment of the present disclosure may include an oil retention feature for mitigating hydrolock in the radial engine 200. Radial engine 200 may include a crank pin 205 mechanically attached to the center of a connecting rod 220, and aligned parallel to a main crankshaft (not shown). The radial engine 200 may include a plurality of cylinders 210 that extend radially outward from the connecting rod 220. Each cylinder 210 includes an axis that is aligned coplanar in a radial configuration. The exemplary radial engine 200 may include nine (9) cylinders and is not meant to be limiting in any way. [0025] The radial engine 200 may further include a plurality of pistons 230 (nine (9) in the present exemplary embodiment) wherein each piston 230 may include a pin 240 that is an attachment or coupling mechanism for securing each piston 230 to a respective connecting rod 220. Each pin 240 of each piston 230 may secure the respective piston 90 to a piston rod (not shown). Each piston rod is attached directly to the connecting rod 220, and supports and governs the movement of its respective piston 230. Each piston 230 may include a crown 250 and a skirt 260. Each piston 230 and cylinder 210 combination may further include an intake and exhaust valve, 270 and 280, respectively. Each piston 230 may also include a sealing ring 290 oriented toward crown 250, on each inner side of piston 230. Each piston 230 and cylinder 210 combination may define a combustion chamber 215.

[0026] Upon shut down of radial engine 200, oil may accumulate due to oil flow or migration due to gravity. Oil flows in a downward direction (toward the bottom of Figure 8) along the inner walls of each cylinder 210. As oil travels it may migrate to the piston 230 via a cavity 310 situated in crown 250, and may navigate and migrate around sealing ring 290 while continuously flowing, resulting in excess oil, and possibly substantially all of the oil, being captured and retained within cavity 310 and oil retention wells, chambers or cavities 300. The captured oil volume is identified and labeled with V as best shown in Figure 10. The cavity 300 of the piston 230 differs from retention chamber 140 as shown in Figure 3 in that cavity 300 is geometrically and structurally configured to acquire and capture a materially larger volume of oil than retention well 140. Retention wells 300 advantageously provide acquisition compartments located within crown 250 of piston 230. The combination of cavity 310 and oil retention well 300 result in little or substantially no oil flowing onward and out of piston 230 into the bottom of combustion chamber 135 where it would otherwise accumulate and cause hydrolock during shutdown of the radial engine 200.

[0027] Each cavity 310 provides additional capacity to capture and store oil and generally works in conjunction with a respective oil retention cavity 300.

Cavities 310 and oil retention wells 300 work to greatly reduce or substantially eliminate the problem of oil being left over in the bottom of the crankcase as well as in a combustion chamber 215. The result is that the issue of hydrolock is substantially eliminated and the risk of damage to radial engine 200 is thereby substantially eliminated. In one exemplary embodiment, each piston 230 may be configured to hold approximately 80-90% of the internal oil volume from the crankshaft (not shown) and rod 220. With particular reference to Figures 10 and 14, each cavity 310 and oil retention well 300 provide a larger voluminous area to capture and retain flowing oil as compared to retention chamber 140 of the engine 10 of Figure 3.

[0028] It will be appreciated that the aforementioned process and devices may be modified to have some steps removed, or may have additional steps added, all of which are deemed to be within the spirit of the present disclosure. Even though the present disclosure has been described in detail with reference to specific embodiments, it will be appreciated that various modifications and changes can be made to these embodiments without departing from the scope of the present invention as set forth in the claims. Accordingly, the specification and the drawings are to be regarded as an illustrative instead of merely restrictive thought of the scope of the present disclosure.

[0029] WE CLAIM: