US3782121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Actuator apparatus
Assignee: Texas Instruments Inc
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Filing: 1972-05-01
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Granted: 1974-01-01
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Expires: 1992-05-01
Abstract
Abstract An actuator for converting electrical energy into linear mechanical movement comprises a chamber containing an expandable material and a positive temperature coefficient (PTC) of resistance heater located in thermal communication with the chamber. A first piston transmits force from the expandable material to an external load against the force of a first return spring. The first piston moves out of a casing from a retracted position at a first stop to a protracted position at a second stop at which point continued expansion of the expandable material in one embodiment causes a second piston to separate the chamber from the heat source against the bias of a second return spring. As the chamber separates the thermal resistance between the heat source and the chamber greatly increases until equilibrium is obtained between heat input to the expandable medium and pressure exerted by the medium. Another embodiment particularly useful for high ambient temperatures and for a longer time period before the actuator returns to its at rest position after deenergization of the heat source employs a chamber fixed in the casing but having a secondary piston which moves to expand the chamber volume to match the volume increase of the expandable material. Several variations are shown for mounting the actuator to a support.
Inventors
- 👤 L Marcoux
- 👤 P Berg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 06:19
CPC Classifications
G; G12; G12B; G12B1/00
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
145 words
Actuator apparatus comprising a hollow casing defining a cavity therein; a chamber having first and second force output means received in the cavity, a thermally expandable medium contained in the chamber, energizable heat source means mounted in thermal communication with the thermally expandable medium, a first piston member slidably mounted in the casing and movable relative to the cAsing from a retracted position to a protracted position, means coupling the first piston member to the first force output means of the chamber to cause movement of the first piston member from the retracted position to the protracted position upon sufficient expansion of the medium, a second piston member mounted in the casing for movement relative to the chamber, and means coupling the second piston member to the second force output means of the chamber to cause movement of the second piston relative to the chamber.
Claim 2
Dependent Claim
145 words
Actuator apparatus comprising a hollow casing defining a cavity therein; a chamber having first and second force output means received in the cavity, a thermally expandable medium contained in the chamber, energizable heat source means mounted in thermal communication with the thermally expandable medium, a first piston member slidably mounted in the casing and movable relative to the cAsing from a retracted position to a protracted position, means coupling the first piston member to the first force output means of the chamber to cause movement of the first piston member from the retracted position to the protracted position upon sufficient expansion of the medium, a second piston member mounted in the casing for movement relative to the chamber, and means coupling the second piston member to the second force output means of the chamber to cause movement of the second piston relative to the chamber.
Claim 3
Dependent Claim
113 words
An actuator according to claim 1 in which the second force output means of the chamber is formed by means defining a bore, the second piston member slidably mounted in the bore, and means biasing the piston member toward the expandable medium, the biasing means placing a given force on the second piston member which force is greater than that required to move the first piston member from the retracted to the protracted position whereby continued expansion of the medium after the first piston has moved to the protracted position will cause the second piston member to move in a direction away from the medium to increase the effective volume of the chamber.
Claim 4
Dependent Claim
121 words
An actuator according to claim 1 in which the second force output means of the chamber is formed by means defining a bore, the second piston member mounted within the bore, means limiting movement of the second piston member away from the medium, the chamber slidably mounted within the cavity, means biasing the chamber in a direction generally parallel to the axis of the bore, the biasing means placing a given force on the chamber in excess of a predetermined force used for moving the first piston member from the retracted to the protracted position whereby continued expansion of the medium after the first piston has moved to the protracted position will cause the chamber to move relative to the casing.
Claim 5
Dependent Claim
89 words
An actuator according to claim 3 in which the heat source is mounted in the casing and the biasing means places a force on the chamber tending to maintain the chamber in close thermal communication with the heat source, movement of the chamber caused by continued expansion of the medium after the first piston member has moved to the protracted position will reduce heat received by the medium within the chamber and an equilibrium will be effected between heat input to the medium and pressure exerted by the medium.
Claim 6
Dependent Claim
23 words
An actuator according to claim 4 in which the heat source comprises a wafer of material having a positive temperature coefficient of resistance.
Claim 7
Dependent Claim
60 words
An actuator according to claim 5 in which the expandable medium has a solid to liquid phase change temperature range and the heat source wafer has a anomaly temperature above which the wafer has a steeply sloped positive temperature coefficient of resistance, the anomaly temperature being higher than the solid to liquid phase change temperature range of the expandable medium.
Claim 8
Dependent Claim
229 words
An actuator comprising a casing defining a cavity therein, electrical energizing means mounted in the casing, a chamber having first and second force output means mounted in the cavity in energy receiving relationship with the electrical energy means, an expandable medium contained in the chamber, a first piston member slidingly mounted in the casing between a retracted and a protracted position, the piston member having a force receiving surface located in force receiving relation with the first force output means of the chamber, a second piston means mounted in the casing, the second piston means having a force receiving surface located in force receiving relation with the second force output means of the chamber, the second force receiving surface larger than the first force receiving surface, and means biasing the second piston means in a direction opposed to the force exerted by the expandable medium, the biasing means exerting a given force on the second piston means in excess of a predetermined force used for moving the first piston member from thE retracted to the protracted position whereby the expandable medium expands upon electrical energization causing the first piston member to move from the retracted position to the protracted position, continued expansion of the expandable medium causes relative movement of the second piston means until an equilibrium is reached between power input and pressure exerted by the expandable medium.
Claim 9
Dependent Claim
229 words
An actuator comprising a casing defining a cavity therein, electrical energizing means mounted in the casing, a chamber having first and second force output means mounted in the cavity in energy receiving relationship with the electrical energy means, an expandable medium contained in the chamber, a first piston member slidingly mounted in the casing between a retracted and a protracted position, the piston member having a force receiving surface located in force receiving relation with the first force output means of the chamber, a second piston means mounted in the casing, the second piston means having a force receiving surface located in force receiving relation with the second force output means of the chamber, the second force receiving surface larger than the first force receiving surface, and means biasing the second piston means in a direction opposed to the force exerted by the expandable medium, the biasing means exerting a given force on the second piston means in excess of a predetermined force used for moving the first piston member from thE retracted to the protracted position whereby the expandable medium expands upon electrical energization causing the first piston member to move from the retracted position to the protracted position, continued expansion of the expandable medium causes relative movement of the second piston means until an equilibrium is reached between power input and pressure exerted by the expandable medium.
Claim 10
Dependent Claim
196 words
Actuator apparatus for translating electrical energy into linear mechanical movement comprising: a casing defining a cavity therein, the casing having a top wall with an aperture extending therethrough into the cavity, a chamber formed of thermally conductive material having first and second bores communicating with the chamber, the chamber received in the casing, a thermally expandable medium contained in the chamber, an electrical resistance heater received in the casing in thermal communication with the chamber, a first piston member slidably received in the casing cavity movable between a retracted position and a protracted position, the piston member having a first force receiving surface positioned within the first bore of the chamber, first return spring means positioned in the casing cavity and biasing the first piston member toward its retracted position, means to electrically energize the electrical resistance heater, second piston means including a member having a second force receiving surface received in the second bore of the chamber, the second force receiving surface movable relative to the chamber, and second return spring means preventing relative movement of the second force receiving surface and the chamber until a predetermined force is exerted on the first piston member.
Claim 11
Dependent Claim
196 words
Actuator apparatus for translating electrical energy into linear mechanical movement comprising: a casing defining a cavity therein, the casing having a top wall with an aperture extending therethrough into the cavity, a chamber formed of thermally conductive material having first and second bores communicating with the chamber, the chamber received in the casing, a thermally expandable medium contained in the chamber, an electrical resistance heater received in the casing in thermal communication with the chamber, a first piston member slidably received in the casing cavity movable between a retracted position and a protracted position, the piston member having a first force receiving surface positioned within the first bore of the chamber, first return spring means positioned in the casing cavity and biasing the first piston member toward its retracted position, means to electrically energize the electrical resistance heater, second piston means including a member having a second force receiving surface received in the second bore of the chamber, the second force receiving surface movable relative to the chamber, and second return spring means preventing relative movement of the second force receiving surface and the chamber until a predetermined force is exerted on the first piston member.
Claim 12
Dependent Claim
51 words
An actuator according to claim 8 in which the location of the chamber is fixed within the casing cavity, the second return spring biasing the member of the second piston means inwardly toward the interior of the chamber, and means limiting inward movement of the member of the second piston means.
Claim 13
Dependent Claim
103 words
An actuator according to claim 8 in which the chamber has a generally cylindrical body portion having two opposite ends, a first elongated sleeve portion of reduced diameter and an intermediate truncated portion joining one end of the body portion with the first sleeve portion, and a bottom wall having an aperture therein located at the second end of the body portion, the bottom wall formed with a second elongated sleeve in communication with the aperture in the bottom wall and extending into the interior of the chamber, the first sleeve defining the first bore and the second sleeve defining the second bore.
Claim 14
Dependent Claim
62 words
An actuator according to claim 10 in which a first floating piston member is received in the first bore, a second floating piston member is received in the second bore, the floating piston members each having a groove formed therein and elastomeric sealing means received in each respective groove tightly fitting between the piston members and the surfaces defining the respective bores.
Claim 15
Dependent Claim
68 words
An actuator according to claim 10 in which the chamber is movably received in the casing cavity and is formed with an outwardly extending radial flange, a shelf is formed in the casing, the second return spring is a helical spring extending between the radial flange of the chamber and the shelf of the casing, and means is provided to limit outward movement of the second piston member.
Claim 16
Dependent Claim
29 words
An actuator according to claim 12 in which the first and second bores are circular and the diameter of the second bore exceeds the diameter of the first bore.
Claim 17
Dependent Claim
24 words
An actuator according to claim 8 in which the electrical resistance heater comprises a wafer of material having a positive temperature coefficient of resistance.
Claim 18
Dependent Claim
27 words
An actuator according to claim 14 in which the wafer is comprised of barium titanate doped with a rare earth, the wafer having two metallized opposite faces.
Claim 19
Dependent Claim
81 words
An actuator according to claim 15 including first and second termiNal means extending from without the casing into the casing cavity, the first terminal having a surface extending laterally across the cavity, the second terminal having a laterally extending platform within the cavity, one face of the wafer bonded to the laterally extending surface of the first terminal and an electrically conductive spring biased into electrical contact between the other face of the wafer and the platform of the second terminal.
Claim 20
Dependent Claim
32 words
An actuator according to claim 16 in which the chamber is formed with a bottom wall which is located adjacent the laterally extending surface of the first terminal in thermal communication therewith.
Claim 21
Dependent Claim
32 words
An actuator according to claim 17 in which a heat conductive force distributing plate is placed between the laterally extending surface of the first terminal and the bottom wall of the chamber.
Claim 22
Dependent Claim
105 words
An actuator according to claim 8 in which the first piston member is formed with a rod portion which extends through the aperture formed in the top wall of the casing, a projecting surface is formed on the piston member and is adapted to abut an interior stop surface of the top wall to limit outward movement of the piston member, a stop shelf is formed in the casing cavity, the piston is formed with a surface adapted to abut the stop shelf to limit inward movement of the piston member whereby the piston movement is accurately determined by the distance between the two stops.
Claim 23
Dependent Claim
24 words
An actuator according to claim 19 including a spacer mounted on the rod portion of the first piston member to shorten the piston movement.
Claim 24
Dependent Claim
39 words
An actuator according to claim 8 in which the casing is generally cylindrical and is formed with a plurality of lands and grooves, the grooves adapted to receive snap rings for mounting of the actuator in desired adjusted position.
Claim 25
Dependent Claim
124 words
Actuator apparatus comprising a hollow casing defining a cavity therein; a chamber having a force output means received in the cavity, a thermally expandable medium contained in the chamber, energizable heat source means mounted in thermal communication with the thermally expandable medium, a piston member slidably mounted in the casing and movable relative to the casing from a retracted position to a protracted position, means coupling the piston member to the force output means of the chamber to cause movement of the piston member from the retracted position to the protracted position upon sufficient expansion of the medium, and means for moving the chamber relative the heat source means to decrease heat input to the medium when the piston moves to the protracted position.
Claim 26
Dependent Claim
124 words
Actuator apparatus comprising a hollow casing defining a cavity therein; a chamber having a force output means received in the cavity, a thermally expandable medium contained in the chamber, energizable heat source means mounted in thermal communication with the thermally expandable medium, a piston member slidably mounted in the casing and movable relative to the casing from a retracted position to a protracted position, means coupling the piston member to the force output means of the chamber to cause movement of the piston member from the retracted position to the protracted position upon sufficient expansion of the medium, and means for moving the chamber relative the heat source means to decrease heat input to the medium when the piston moves to the protracted position.
References Cited (Backward Citations)
US3431726A
Cited
US3430440A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |