Mechanical positioner for reclining seat assembly
View Patent ↗A mechanical linear actuator having a tubular member that is defined by a housing for rotatably and axially supporting a circular nut, a lead screw is mated to the circular nut so that it can move axially in and out of the tubular member. A torsion spring clutch brake is wound about the circular nut to normally brake the nut and thus prevent the lead screw from moving into or out of the tubular member. An unlocking mechanism can remotely unwind the torsion spring clutch brake to sufficiently release the circular nut and thus allow the lead screw to pass in and out of the tubular member. An adjustable stop is provided for adjusting the stroke of the actuator.
1. A mechanical linear actuator that includes:
a housing having an opening that extends axially through said housing:
an elongated lead screw that is slidably contained within said opening, said lead screw having a male threaded section upon the outer surface thereof;
a cylindrical drive nut mounted for rotation within said housing, said cylindrical nut having an axial outer diameter and a female thread that mates with said male thread on said lead screw so that said lead screw can move axially within said opening as said cylindrical nut rotates within said housing;
a spring clutch brake for engaging said axial outer diameter of said cylindrical drive nut when said spring clutch brake is in a first position to restrain said drive nut from rotating and for releasing said cylindrical drive nut when in a second release position wherein said cylindrical drive nut can freely rotate within said housing; and
said spring clutch brake being manually movable between said first and second positions.
2. The actuator of claim 1 that includes a stroke limiting device.
3. The actuator of claim 2 that includes an adjustable stroke limiting device.
4. The actuator of claim 2 that includes a lockable stroke limiting device.
5. The actuator of claim 1 that further includes a first coupler located at a free end of said housing and a second coupler located at a free end of said lead screw.
6. The actuator of claim 5 wherein one of said couplers rotatably connects one end of said actuator to the stationary seat of a chair having a reclining back rest and the other of said couplers connect the other end of said actuator to linkage for reclining said back rest so that said back rest moves from a fully upright position to a reclined position as the length of the actuator is compressed.
7. The actuator of claim 1 that further includes a spring for urging said spring clutch brake into said first position.
8. The actuator of claim 1 which includes a tubular member on the end of the housing which includes at least one slotted opening that extends axially along a length of said tubular member and a guide pin secured in said lead screw that passes outwardly through said at least one slotted opening whereby said guide pin rides in said at least one slotted opening when the lead screw moves within said tubular member.
9. The actuator of claim 8 wherein said tubular member contains a threaded section upon its outer surface which is substantially coextensive in length with said at least one slotted opening.
10. The actuator of claim 9 that further includes a stop nut threadably mounted upon said threaded section of said tubular member which intercepts the progress of said guide pin as said lead screw advances into said tubular member thus limiting the axial travel of said lead screw.
11. The actuator of claim 10 that further includes at least one set screw that is threaded radially into said stop nut to contact said outer surface of said tubular member and secure said stop nut in a desired location.
12. The actuator of claim 11 wherein said tubular member contains a pair of parallelly aligned slotted openings and said guide pin passes outwardly through each of said openings to intercept said stop nut.
13. The actuator of claim 1 wherein said spring brake clutch includes a torsional spring that is wound about the outer diameter of said cylindrical nut.
14. The actuator of claim 13 wherein said torsional spring includes an axially disposed first tab at one end of said torsional spring and a second radially disposed tab at the other end of said torsional spring.
15. The actuator of claim 14 wherein said first tab is contained within an axially aligned cutout in said housing so as to prevent said first tab from moving circumferentially within said housing and said second tab passes through a circumferential opening in said housing to permit the second tab to rotate between a first position wherein the spring clutch brake locks said drive nut against further rotation and a second position wherein said spring clutch brake unlocks said drive nut for free rotation within said housing.
16. The actuator of claim 15 that further includes a lever arm that acts against said second tab to urge said second tab into said second position when manually moving spring clutch brake between said first and second positions.
17. The actuator of claim 16 that further includes a control means for remotely moving said second tab from said first position into said second position.
18. The actuator of claim 1 wherein said spring clutch brake includes a torsional spring that is wound about said drive nut in a direction such that the holding force of said spring clutch brake increases its hold on said drive nut as the actuator is loaded in one direction, and decreases its holding force on said drive nut as the actuator is loaded in the other direction; said holding force on drive nut can be overridden by manually forcing said actuator in said other direction.
19. The actuator of claim 1 that includes a compression spring that extends the actuator when said spring clutch brake is in the second release position.
20. A mechanical linear actuator comprising:
a housing having an opening that extends axially through said housing:
an elongated lead screw that is slidably contained within said opening, said lead screw having a male threaded section upon the outer surface thereof;
a cylindrical drive nut mounted for rotation within said housing, said cylindrical nut having an axial outer diameter and a female thread that mates with said male thread on said lead screw so that said lead screw can move axially within said opening as said cylindrical nut rotates within said housing;
a spring clutch brake for engaging said axial outer diameter of said cylindrical drive nut when said spring clutch brake is in a first position to restrain said drive nut from rotating and for releasing said cylindrical drive nut when in a second release position wherein said cylindrical drive nut can freely rotate within said housing, said spring clutch brake being manually movable between said first and second positions, said spring brake clutch including a torsional spring that is wound about an axial portion of the outer diameter of said cylindrical nut wherein said torsional spring further includes an axially disposed first tab at one end of said torsional spring and a second radially disposed tab at the other end of said torsional spring, said first tab being contained within an axially aligned cutout in said housing so as to prevent said first tab from moving circumferentially within said housing and said second tab passes through a circumferential opening in said housing to permit the second tab to rotate between a first position, wherein the spring clutch brake locks said drive nut against further rotation and a second position wherein said spring clutch brake unlocks said drive nut for free rotation within said housing.