A pressure cap structure for a cooling system having variable opening pressure, which is applied to a cooling system for circulating cooling water to radiate heat generated by an engine of a vehicle, and maintains the inside pressure of the cooling system in a predetermined range, the pressure cap may include a positive pressure spring mounted in a valve body, and operated to connect the cooling system to the outside when the pressure of the cooling system rises, and a shape memory member restored to the initial shape when reaching a predetermined temperature, and mounted between the positive pressure spring and a spring guard supporting the positive pressure spring.

A dual chamber coolant reservoir having a single vent neck. The coolant reservoir is for an internal combustion engine cooling system wherein the reservoir housing includes a first chamber and a second chamber formed integral thereto. A vent neck includes an aperture for accessing the first chamber with either a two or three o-ring cap to maintain pressure within the first chamber. Means for venting the second chamber when coolant exceeds a predetermined pressure level and a means for venting the first and second chamber when said cap is moved from a closed position to an open position. An inline pressure relief valve and check valve providing pressure relief and air displacement.

The present invention provides a pressure-release sealing cap for a reservoir including a rotatable platform with a ramp connected to a rotatable enclosure. A movable plunger with connected to a movable pressure-release member with a guide stud and a valve means. The guide stud disposed on said ramp between said first and second reference portions, while said sealing cap is installed on said reservoir and the guide stud disposed to rotate on the ramp on rotation of the enclosure to lift the valve means, to release the excess pressure while concurrently removing the sealing cap from the reservoir. The pressure-releasing member is actuated indirectly to release excess pressure from the reservoir, in a controlled and gradual manner.

A safety cap device for controlling a pressure in a radiator includes a valve seat provided with a valve receiving space in which a first communicating hole is formed. A negative pressure valve is provided movably in the first communicating hole. A seal is disposed on a receiving surface of the valve seat and disposed movably with the negative pressure valve. The seal has a second communicating hole formed at a central portion thereof. A positive pressure valve is disposed on the seal and has a third communicating hole formed at a central portion thereof. A cap covers an upper portion of the valve seat. A spring is interposed between the positive pressure valve and the cap. A fluid receiving part is in the valve seat to prevent cavitation caused when an internal fluid expands.

A non-negative pressure radiator cap is provided and includes a pressure valve having a pressure member, disposed inside a body while having an aperture formed therein. The pressure member is pressed based on an increase in pressure of coolant to move coolant toward a reservoir tank. Additionally, a vacuum valve that includes a head part and a neck part moves vertically based on the pressure of the coolant to open or close the aperture. The neck part passes through the aperture from bottom to top. A sealing member is disposed between the pressure valve and the vacuum valve and has an insertion aperture that is formed at a position corresponding to the aperture of the pressure valve. A retainer is further inserted into the aperture and the insertion hole and a guide directs the vacuum valve to move vertically when the vacuum valve is opened or closed.

A radiator cap includes a top cover unit, an intermediate seat unit, an output valve unit, and an input valve unit. The top cover unit includes cover body, a stem, and a plurality of positioning member to be fastened to a radiator opening. A washer surrounds the stem. The intermediate seat unit includes a connecting tube and a connecting seat connected to each other. The output valve unit includes a valve seat connected to the connecting seat. The valve seat has hook portions engaged with guiding recesses of the connecting seat. A valve disc is connected to the valve seat. A first spring is disposed between the valve seat and the connecting seat. The input valve unit includes a pin rod, and a second spring to bias the pin rod to thereby abut against the valve disc so as to close a valve hole.