Patent 8074673 Issued on December 13, 2011. Estimated Expiration Date: June 16, 2029. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
A freeze-resistant metering valve is provided that comprises a magnetic part and a hydraulic part. The magnetic part has an armature biased by a spring. The hydraulic part has an annular space for receiving and conveying a liquid as well as a tappet facing a valve seat. The valve seat comprises a nozzle opening on the side facing away from the tappet. In a currentless state, the tappet blocks the annular space in the direction of an opening (nozzle opening) until a freezing pressure exerted onto the armature generates a sufficient force by virtue of the solidifying liquid. This force is used to counteract the spring force until a freeze expansion space is created by way of a relieving motion.
Burkert Fluid Control Systems, “Solenoid Valves with Piston, Servo-Assisted”, archived Jan. 10, 2005.