Patent ID: 7611001

Claim:
A plugged filter detection system comprising: a valve housed within a cavity, said cavity defining an initial inlet for receiving fluid at an inlet pressure before said fluid enters a filter, a final inlet for receiving fluid at an outlet pressure after said fluid exits said filter; wherein said valve includes a pair of larger diameter portions and a smaller diameter portion extending between said larger diameter portions to define a secondary cavity between said larger diameter portions such that said fluid is prevented from flowing around said larger diameter portions between said cavity and said secondary cavity; an activation inlet, wherein fluid enters said secondary cavity through said activation inlet at a control pressure; a switch port for directing fluid in said secondary cavity to a switch thereby activating said switch; wherein said inlet pressure biases said valve in a first direction and said outlet pressure biases said valve in a second direction substantially opposing said first direction; said valve being movable from a first position, wherein said activation inlet is blocked, to a second position, wherein said activation inlet is unblocked, thereby allowing said switch to be activated when said inlet pressure is greater than said outlet pressure; and wherein said final inlet is coupled to a vehicle lockup clutch such that said fluid only enters said cavity through said final inlet when said lockup clutch is engaged; wherein failure of said valve to move from said first position to said second position upon disengagement of said lockup clutch indicates that at least one of said valve and said switch are not working properly.