Fail-safe thermostat for vehicular cooling systems

A vehicular thermostat for controlling flow of coolant in a passageway between a coolant pump and a radiator comprising:

• cylindrical means defining a central interior chamber having an open end;
• central rod means extending into the interior chamber through the open end and having a free end adjacent the passageway;
• seal means within the cylindrical means slidably engaged to the central rod means and closing the open end of the interior chamber;
• a temperature responsive medium filling the interior chamber, said medium volumetrically changing with temperature to act against the central rod means and exert force on the cylinder means to displace the same axially in a first direction;
• valve means coupled to the cylindrical means and movable therewith, the coupling including a temperature responsive alloy material;
• thermostat housing means mountable in fixed relation to the passageway and coupled to the free end of the central rod to hold the central rod in fixed relation;
• and
• means including a spring means disposed between the valve means and the thermostat housing means for (1) opposing movement of the valve means in the first direction and (2) shifting the position of the valve means if the coolant exceeds a predetermined temperature and melts the temperature responsive alloy material.

A fail-safe thermostat for automotive vehicles comprising:

• a cylindrical body having an interior chamber;
• flow valve means coupled to the cylindrical body, the flow valve means including a fixed ring outer portion and a movable disk central portion;
• central rod means coupled to the fixed outer portion and extending into the interior chamber;
• temperature responsive wax means within the interior chamber and expanding under normal temperature conditions to urge the cylindrical body in a first direction by exerting force against the central rod means;
• means including fusible alloy means coupling the movable disk central portion of the flow valve means to the cylindrical body to move the cylindrical body and the movable disk portion in a first direction in response to increasing temperature, the fusible alloy being positioned to release the movable disk from force exerted against the central rod means by the wax means upon melting when a predetermined temperature above the normal operating temperature is reached;
• and
• spring means coupled between the fixed outer portion and the movable disk portion to resiliently oppose movement in the first direction and to force the movable disk in a second direction to open the valve when the fusible alloy means melts.

A fail-safe thermostat for coolant flow control in the flow control junction of a vehicular cooling system having a radiator passageway leading to at least one engine block coolant passageway transverse thereto and an aligned bypass passageway, comprising:

• cylindrical sleeve means defining a central chamber, the cylindrical sleeve means being positioned in the flow control junction and having a first end extending toward the bypass junction;
• an outer ring valve member mounted in the flow control junction to partially block flow between the radiator passageway and engine block passageway;
• first support means at the bypass side coupling the outer ring valve member to the cylindrical sleeve means at an intermediate region thereon;
• an inner disk valve member coupled to the cylindrical sleeve means and positioned within the outer ring valve member to block flow between the radiator passageway and engine block passageway;
• a central rod extending into the central chamber of the cylindrical sleeve means from a second end adjacent the radiator passageway;
• second support means on the radiator passageway side coupling the central rod to the outer ring valve member;
• means slidably sealing the central rod within the cylindrical sleeve means to define a closed central chamber;
• thermally responsive means filling the closed central chamber about the central rod to exert axial force thereon in response to coolant temperature such as to slide the cylindrical sleeve means and the inner disk valve member in the direction toward the bypass passageway;
• first compression spring means disposed between the inner disk valve member and the first support means to resiliently oppose motion of the inner disk valve member toward the bypass passageway;
• thermally responsive fusible alloy means coupled between the inner disk valve member and the cylindrical sleeve means to release the inner disk valve means from the central rod at a predetermined temperature above normal operating temperature such that the inner disk valve means is urged away from the bypass passageway by the first compression spring means, to open the valve;
• bypass valve means slidably positioned on the first end of the cylindrical sleeve means for selectively closing the bypass passageway;
• and
• second compression spring means coupled between the first support means and the bypass valve means for resiliently urging the bypass valve means toward the bypass passageway.