Oil filter apparatus

Claim 1

In an oil filter system, wherein system oil is pumped in a generally closed loop within a machine to be lubricated, an oil filter releasably mounted upon the machine said oil filter comprising a generally closed oil cannister having at least one oil inlet port fashioned through one end thereof and at least one oil outlet port fashioned through the same end thereof and an oil filter media mounted within the cannister such that system oil may be pumped from a first oil passage within the machine to be lubricated into the cannister via the at least one oil inlet port, through the oil filter media to filter the oil, out of the oil cannister and back into the machine via the at least one oil outlet port in the oil cannister and a second oil passage within the machine to be lubricated downstream of the first oil passage, the improvement comprising: a disc element operable to be releasably mounted between the oil filter and the machine to be lubricated, said disc element having generally mutually parallel and opposing end surfaces and being operable to abut against and sealingly engage with compatible surfaces on the machine to be lubricated and the one end of the oil cannister respectively; first disc passage means extending through said disc element from one of said opposing end surfaces to the other and in fluid communication at one end with said at least one oil inlet port into the oil cannister and in fluid communication at the other end with the oil passage within the machine to be lubricated; second disc passage means extending through said disc element from one of said opposing end surfaces to the other and in fluid communication at one end with said at least one oil outlet port from the oil cannister and in fluid communication at the other end with the second oil passage downstream of the first oil passage, within the machine to be lubricated; bypass passage means fashioned within said disc element and communicating said first disc passage means and said second disc passage means for permitting oil to bypass the oil filter element through the disc element; a normally closed check valve positioned within said bypass passage means and having an upstream side in fluid communication with said first disc passage means and a downstream side in fluid communication with said second disc passage means, said check valve being operative to open in response to a predetermined pressure buildup within said first disc passage means; means for detecting the opening of said check valve such as when a clogged filter element produces a predetermined pressure buildup upstream of said check valve; warning signal means operably connected to said means for detecting the opening of said check valve; and an electrical circuit including a transistor switch including a common ground transistor wherein the base of said transistor is connected to a ground potential through said check valve means.