| 摘要 |
A pivoting permanent-magnet armature of an electromagnet forming part of a controller to limit the flow of an intravenous solution through a casette to a patient. The electromagnet may have an E-frame with the permanent magnet pivoting between two positions about a point lying on the extension of the electromagnet's middle leg. In one position, one pole of the permanent magent contacts one side leg of the E-frame to open the casette inlet and maintain the outlet in a closed configuration. In the other position, the permanent magnet's other pole contacts the other side of the E-frame to close the inlet, open the outlet, and allow fluid to flow to the patient. A gap should remain between the permanent magnet and the E-frame's middle leg to avoid their grinding together and a concomitant increase of friction due to the presence of resulting particles. Preventing contact between the permanent magnet and the electromagnet's middle leg also avoids the formation of the magnetic shunt between the two at that point. This has particular importance when the armature assumes the form of a rocker arm with two separate permanent magnets attached at its ends. A strip of plastic attached to either the middle leg of the E-frame or to the rocker-arm armature achieves the magnetic separation of the components but then allows mechanical contact to statilize their operation.
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