Liquid level indicator

#Adequate lubrication of the operating components of a reciprocating piston internal combustion engine is essential since relative motion between unlubricated contacting surfaces will cause excessive wear, overheating, and seizure of the components. The energy loss associated with engine wear and overheating will also result in reduced engine power and efficiency.

#A typical reciprocating piston internal combustion engine is equipped with a crankcase oil pan or reservoir for storing the lubricant necessary for normal engine lubrication. An oil pump transports the lubricant to the operating components of the engine. In order to provide sufficient oil pressure at the operating components for adequate lubrication, the oil pump inlet is generally submerged in the reservoir below the surface of the oil, which must be maintained above some minimum level in order to provide sufficient head over the pump inlet and to enable any necessary splash lubrication.

#At present, a dipstick is commonly used to determine the level of oil in the crankcase reservoir. The oil level is read by removing the dipstick from the reservoir and comparing the location of the residual oil on the dipstick to lines scribed thereon. The use of a dipstick is inconvenient in a motor vehicle, since the operator must stop the vehicle, and preferably the engine, and dismount to read the dipstick. Nonetheless, dashboard indicators for the level of oil in a motor vehicle oil reservoir are not used. Instead, motor vehicles are equipped with indicators that measure the oil pressure delivered by the oil pump, which is only indicative of inadequate oil in the oil reservoir when there is no longer sufficient oil in the reservoir to keep the pump adequately supplied.

#For a better understanding of the invention, reference may be made to the following description of an exemplary embodiment, taken in conjunction with the figures of the accompanying drawings, in which:

#FIG. 1 is a partial sectional view of a crankcase oil reservoir for a reciprocating piston engine equipped with a liquid level indicator according to the present ivention;

#FIG. 2 is a partial sectional view of an automatic oil refill system for the crankcase oil reservoir of a reciprocating piston engine, which system incorporates the liquid level indicator of the present invention; and

#FIG. 1 of the drawings illustrates the lower portion of the crankcase 10 of a reciprocating piston engine in a motor vehicle and an associated oil pan or reservoir 12 attached to the bottom of the crankcase. The oil pan 12 contains a lubricant 14, such as lubricating oil, which fills the pan to a desired predetermined level 16. A conventional oil pump (not shown) pumps oil from the reservoir 12 and circulates the oil under pressure to the operating components of the engine.

#Within the oil pan 12 is a float 18 which is coupled by a metal clip 20 to a downwardly projecting tubular fitting 22. As illustrated, the float has a tubular projection 24 extending from the top surface thereof which slides over the end of the fitting 22. The clip 20 extends through the tubular projection 24 at two diametrically opposed locations and has lugs that extend radially inwardly of the projection 24 into an annular groove 26 in the outer surface of the fitting 22. The axial width of the annular groove 26 is greater than the thickness of the clip lugs so that the clip 20 and thus the float 18 to which the clip is secured can move vertically for a limited distance along the length of the fitting 22. Engagement between the lugs of the clip 20 and the lower edge of the groove 26 retains the float 18 on the fitting 22 when the oil 14 is drained from the reservoir 12, for example.

#The fitting 22 has a central passageway 27 that is outwardly flared at its lower end. The interior surface of the fitting 22 defining the flared end of the passageway 27 is threaded and threadedly receives a tubular valve seat 28. An outlet orifice 30 in the valve seat 28 communicates with the passageway 27 in the fitting 22 through a passageway 31 in the valve seat. A valve body 32, in the form of a ball, is received in the orifice 30 and is supported by the upper surface of the float 18 forming the closed end of the tubular projection 24. Thus, the axial position of the float 18 relative to the valve seat 28 determines the relative spacing between the sealing surfaces of the valve body 32 and the valve seat 28, and therefore determines the effective crosssectional flow area of the orifice 30.