Patent ID: 7951291

Claim:
An automatic fluid channel screen lock-unlock system, for installation on an apparatus having a rotatable screen, wherein the system as installed on the apparatus comprises: a. an actuator comprising a flapper and a trigger, wherein the flapper is rotatably connected to the screen for allowing the flapper to rotate about a flapper axis, wherein the flapper axis is oriented generally parallel to a screen axis, the screen being supported at least in part by a screen support structure and the screen axis being an axis about which the screen is rotatable relative to the support structure, and wherein the flapper is connected to the trigger for moving the trigger in response to rotation of the flapper; b. a lock bar wherein the lock bar is rotatably attached to the support support structure, the lock bar being rotatable in response to movement of the trigger, wherein the screen includes a blockable part and the lock bar includes a bar front portion and a bar back portion, the bar front portion being located for intercepting a rearward path of the blockable part while the lock bar is in a locked position, for preventing the screen from opening; wherein, c. the flapper is located and oriented with respect to the screen, at least while the flapper is in an at-rest position, for at least part of the flapper to be rotatable rearward in response to pressure from impact fluid; wherein, d. the trigger is located sufficiently close to the lock bar for rotation of the trigger to move the lock bar in a direction and amount needed for at least part of the bar front portion to clear the reward path of the blockable part, thereby permitting the screen to rotate open in response to pressure against the front of the screen, and wherein the screen is rotatable toward a closed position in response to diminishment of the pressure against the front of the screen; wherein, e. the lock bar is biased in a counter-rotation direction by the bar back portion or another biasing device for at least helping hold the lock bar in or returning it to the locked position.