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US 4,090,589 AGranted
Fail safe valve actuator
OwnerJohn Herman Fitzwaterinventor
Life of this patent
Estimating the term…
Abstract
A valve actuator employs a torsion spring type clutch to engage and disengage a drive motor and an output shaft. The torsion spring normally engages and is connected to a gear which may be engaged by a dog to cause disengagement of the clutch. The output shaft carries a pinion which is engaged with a rack carried on a piston which is slidable in a closed fluid containing cylinder. The piston includes an axial passageway with a metering orifice therein which smoothes the operation of the actuator and provides positive stops for the output shaft with a minimization of impact between the piston and the ends of the cylinder.
Claims15
A clutch mechanism for a valve actuator, said clutch mechanism comprising:
- first and second axially aligned and rotatably mounted shafts having adjacent end portions of the same diameter;
- a first shoulder on said first shaft;
- a second shoulder on said second shaft;
- a gear having a central bore receiving said second shaft therethrough, said gear abutting said second shoulder and rotatable about said second shaft;
- a torsion spring about said end portions of said first and second shafts and having a normal diameter that is less than the diameter of said end portions of said first and second shafts, said spring having one end bearing against said first shoulder and a second end connected to said gear, said torsion spring operable to tighten upon and couple said shafts for mutual rotation in response to rotation of said first shaft in a first direction;
- and
- clutch disengagement means including gear engagement means for engaging the teeth of said gear to prevent rotation with said second shaft so that rotation of said second shaft in the opposite direction causes an expansion of the diameter of said spring and disengagement of said shafts.
4 more elements
A fail-safe valve actuator comprising:
- a rotatably mounted output shaft for connection to a valve;
- a drive motor operable in a first direction;
- a gear train connected to said drive motor;
- an intermediate shaft connected to said gear train, said intermediate shaft rotatably mounted adjacent and in axial alignment with said output shaft,
- said output and intermediate shafts having adjacent end portions of the same diameter and respective shoulders spaced from the adjacent ends;
- a clutch gear mounted and rotatable about said adjacent end portion of said output shaft bearing against the respective shoulder;
- a first torsion spring about said end portions connected to said gear and bearing against the shoulder of said intermediate shaft, said first torsion spring having a normal diameter that is less than the diameter of said end portions of said shafts and responsive to rotation of said intermediate shaft in the first direction to couple said shafts for mutual rotation;
- a second torsion spring including a fixed end and an end connected to said output shaft to store energy as said output shaft is rotated in the first direction and serving as a second motor to drive said output shaft in a second direction;
- a brake connected to and operated upon deenergization of said drive motor to hold the above components and the valve in steady state and deenergizable to permit said second torsion spring to release its energy and rotate the output shaft in the second direction;
- and
- gear engaging means operable upon deenergization of said brake to engage said gear and prevent rotation thereof to cause expansion of the diameter of said first torsion spring and uncoupling of said shafts so that said drive motor is disconnected during operation in the second direction.
8 more elements
A mechanism for a valve actuator, said mechanism comprising:
- first and second axially aligned and rotatably mounted shafts having adjacent end portions of the same diameter;
- a first shoulder on said first shaft;
- a second shoulder on said second shaft;
- a gear having a central bore receiving said second shaft therethrough, said gear abutting said second shoulder and rotatable about said second shaft;
- a torsion spring about said end portions of said first and second shafts and having a normal diameter that is less than the diameter of said end portions of said first and second shafts, said spring having one end bearing against said first shoulder and a second end connected to said gear, said torsion spring operable to tighten upon and couple said shafts for mutual rotation in response to rotation of said first shaft in a first direction;
- clutch disengagement means including gear engagement means for engaging the teeth of said gear to prevent rotation with said second shaft so that rotation of said second shaft in the opposite direction causes an expansion of the diameter of said spring and disengagement of said shafts;
- and
- damping means connected to said second shaft, said damping means including means for controlling the speed of rotation of said second shaft.
5 more elements
Dependencies are inferred from the claim text.