US3898614A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Engine overheat sensor
Assignee: Motors Liquidation Co
•
Filing: 1974-09-16
•
Granted: 1975-08-05
•
Expires: 1994-09-16
Abstract
Abstract The invention relates to a pressure and temperatureresponsive switch particularly adapted for monitoring the condition of an automobile engine cooling system. The switch includes a housing having a cylinder bore in which two free-floating pistons are disposed. The innermost piston adjacent the cooling system of the automobile engages the midpoint of a normally arcuate metal diaphragm member which separates the piston from the cooling system. Above the inner or first piston is an outer or second piston which supports a contact member thereon. The outer end of the housing is closed by a cover member which supports a terminal adapted to be engaged by the contact member to energize a warning signal during periods of engine overheat which will cause the second piston to move towards the cover member. The space between the first and second pistons is filled with a refrigerant such as Freon-22 having a predetermined coefficient of expansion per degree of temperature increase. The space between the second piston and the cover member is filled with a refrigerant such as Freon-12 having a lesser coefficient of expansion than the refrigerant between the pistons. A significant decrease of coolant pressure in the engine will cause the arcuate diaphragm to relax and flatten. Resultantly the innermost piston moves downward against the flattened diaphragm which greatly increases the area of contact therebetween and the rate of heat transfer therebetween. This increase in heat causes the refrigerant between the pistons to expand, thereby forcing the outer piston to move in the housing and to engage the contact and terminal thereby energizing a warning signal indicating an overheat condition of the engine.
Inventors
- 👤 Roy E Watt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:18
CPC Classifications
F; F01; F01P; F01P11/00; F01P11/14; B; B60; B60K; B60K11/00; B60K11/02
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
335 words
A fluid pressure and temperature responsive sensor for use in an engine overheat indicating circuit and including a housing; said housing having a cylinder bore therein between inner and outer ends designated with respect to the fluid whose temperature and pressure are to be sensed; the inner end of said housing covered by a flexible metal diaphragm attached thereto along its peripheral edge, one side of said diaphragm being exposed to the fluid whereby fluid pressure causes the diaphragm to curve outward toward the outer end of the housing; a first piston member reciprocably supported in said cylinder bore of said housing adjacent the midpoint of said curved diaphragm thereby providing only limited contact and a resultantly low heat transfer rate between the diaphragm and the first piston; a second piston reciprocably supported in said cylinder bore and positioned outwardly from said first piston; an outer end member overlying and being sealingly attached to the said housing; terminal means supported by said end member and insulated therefrom for connection to an overheat indicating circuit; contact means on said second piston adapted to engage said terminal means when said second piston moves a predetermined distance towards said cover member in response to temperature and pressure changes of the fluid; a first fluid in the space between said first and second pistons which has a predetermined thermal coefficient of expansion; a second fluid between said second piston and said end member which has a lesser coefficient of thermal expansion than said first fluid whereby in response to a decrease in fluid pressure said curved diaphragm moves inward to a more flattened configuration thereby increasing the area of contact between said diaphragm and said first piston and also the heat transfer rate between the fluid and the first thermally expansive fluid to cause the second piston to move upward in a controlled manner against the opposing expansive force of the second fluid thereby eventually causing engagement between the contact and the terminal to complete the overheat indicating circuit.
Claim 2
Dependent Claim
335 words
A fluid pressure and temperature responsive sensor for use in an engine overheat indicating circuit and including a housing; said housing having a cylinder bore therein between inner and outer ends designated with respect to the fluid whose temperature and pressure are to be sensed; the inner end of said housing covered by a flexible metal diaphragm attached thereto along its peripheral edge, one side of said diaphragm being exposed to the fluid whereby fluid pressure causes the diaphragm to curve outward toward the outer end of the housing; a first piston member reciprocably supported in said cylinder bore of said housing adjacent the midpoint of said curved diaphragm thereby providing only limited contact and a resultantly low heat transfer rate between the diaphragm and the first piston; a second piston reciprocably supported in said cylinder bore and positioned outwardly from said first piston; an outer end member overlying and being sealingly attached to the said housing; terminal means supported by said end member and insulated therefrom for connection to an overheat indicating circuit; contact means on said second piston adapted to engage said terminal means when said second piston moves a predetermined distance towards said cover member in response to temperature and pressure changes of the fluid; a first fluid in the space between said first and second pistons which has a predetermined thermal coefficient of expansion; a second fluid between said second piston and said end member which has a lesser coefficient of thermal expansion than said first fluid whereby in response to a decrease in fluid pressure said curved diaphragm moves inward to a more flattened configuration thereby increasing the area of contact between said diaphragm and said first piston and also the heat transfer rate between the fluid and the first thermally expansive fluid to cause the second piston to move upward in a controlled manner against the opposing expansive force of the second fluid thereby eventually causing engagement between the contact and the terminal to complete the overheat indicating circuit.
Claim 3
Dependent Claim
340 words
A fluid pressure and temperature responsive sensor for use in an engine overheat indicating circuit and including a housing; said housing having a cylinder bore therein between inner and outer ends designated with respect to the fluid whose temperature and pressure are to be sensed; the inner end of said housing covered by a flexible metal diaphragm attached thereto along its peripheral edge, one side of said diaphragm being exposed to the fluid whereby fluid pressure causes the diaphragm to curve outward toward the outer end of the housing; a first piston member reciprocably supported in said cylinder bore of said housing adjacent the midpoint of said curved diaphragm thereby providing only limited contact and a resultantly low heat transfer rate between the diaphragm and the first piston; a second piston reciprocably supported in said cylinder bore and positioned outwardly from said first piston; an outer end member overlying and being sealingly attached to said housing; terminal means supported by said end member and insulated therefrom for connection to an overheat indicating circuit; contact means on said second piston adapted to eNgage said terminal means when said second piston moves a predetermined distance towards said cover member in response to temperature and pressure changes of the fluid; a quantity of organic refrigerant such as compounds of carbon and fluorine in the space between said first and second pistons which has a predetermined thermal coefficient of expansion; a second fluid between said second piston and said end member which has a lesser coefficient of thermal expansion than said first fluid whereby in response to a decrease in fluid pressure said curved diaphragm moves inward to a more flattened configuration thereby increasing the area of contact between said diaphragm and said first piston and also the heat transfer rate between the fluid and said refrigerant to cause the second piston to move upward in a controlled manner against the opposing expansive force of the second fluid thereby eventually causing engagement between the contact and the terminal to complete the overheat indicating circuit.
Claim 4
Dependent Claim
340 words
A fluid pressure and temperature responsive sensor for use in an engine overheat indicating circuit and including a housing; said housing having a cylinder bore therein between inner and outer ends designated with respect to the fluid whose temperature and pressure are to be sensed; the inner end of said housing covered by a flexible metal diaphragm attached thereto along its peripheral edge, one side of said diaphragm being exposed to the fluid whereby fluid pressure causes the diaphragm to curve outward toward the outer end of the housing; a first piston member reciprocably supported in said cylinder bore of said housing adjacent the midpoint of said curved diaphragm thereby providing only limited contact and a resultantly low heat transfer rate between the diaphragm and the first piston; a second piston reciprocably supported in said cylinder bore and positioned outwardly from said first piston; an outer end member overlying and being sealingly attached to said housing; terminal means supported by said end member and insulated therefrom for connection to an overheat indicating circuit; contact means on said second piston adapted to eNgage said terminal means when said second piston moves a predetermined distance towards said cover member in response to temperature and pressure changes of the fluid; a quantity of organic refrigerant such as compounds of carbon and fluorine in the space between said first and second pistons which has a predetermined thermal coefficient of expansion; a second fluid between said second piston and said end member which has a lesser coefficient of thermal expansion than said first fluid whereby in response to a decrease in fluid pressure said curved diaphragm moves inward to a more flattened configuration thereby increasing the area of contact between said diaphragm and said first piston and also the heat transfer rate between the fluid and said refrigerant to cause the second piston to move upward in a controlled manner against the opposing expansive force of the second fluid thereby eventually causing engagement between the contact and the terminal to complete the overheat indicating circuit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |