초록 ▼

A simple, inexpensive and reliable screw type linear actuator includes a drive screw, a nut disposed thereon, and a reciprocating drive tube radially disposed over at least a portion of the drive screw. A first clutch member has a first clutch surface bearing upon a complimentary clutch surface whic

A simple, inexpensive and reliable screw type linear actuator includes a drive screw, a nut disposed thereon, and a reciprocating drive tube radially disposed over at least a portion of the drive screw. A first clutch member has a first clutch surface bearing upon a complimentary clutch surface which is operatively connected to the drive tube, whereby outboard movement of the nut upon rotation of the drive screw causes the first clutch surface on the first clutch member to bear upon the complimentary clutch surface and urge the drive tube in a direction toward the outboard end of the drive screw. A compression member urges the first clutch member axially away from the nut, and a retainer allows only limited axial movement of the nut with respect to the drive screw, whereby the nut and the first clutch member are always maintained in splined engagement. The resulting arrangement provides an overunning nut which relies on a clutch mechanism, and a compression member which exerts a separating force between the clutch mechanism and the nut to ensure that the amount of torque needed to cause the nut to overrun always exceeds the frictional torque between the drive screw and the nut, irrespective of the axial load or force which is applied to the linear actuator.

대표청구항 ▼

A linear actuator for articulated beds, comprising: a drive screw having an inboard end, an outboard end, and external threads; a nut disposed on and threadingly engaging the external threads of said drive screw; a reciprocating drive tube radially disposed over at least a portion of said drive scre

A linear actuator for articulated beds, comprising: a drive screw having an inboard end, an outboard end, and external threads; a nut disposed on and threadingly engaging the external threads of said drive screw; a reciprocating drive tube radially disposed over at least a portion of said drive screw; a first clutch member disposed operably between said nut and said drive tube, and being splined with said nut, whereby rotation of said nut causes rotation of said first clutch member while allowing axial movement therebetween; said first clutch member including a first clutch surface which faces toward the outboard end of said drive screw; a second clutch member disposed operably between said first clutch member and said drive tube, and being connected with said drive tube for rotation therewith; said second clutch member including a second clutch surface which faces towards the inboard end of drive screw, and engages the first clutch surface of said first clutch member, whereby outboard movement of said nut upon rotation of said drive screw urges said drive tube in a direction toward the outboard end of said drive screw; a compression member urging the first clutch surface of said first clutch member into frictional engagement with the second clutch surface of said second clutch member; a first stop generally disposed near the outboard end of said drive screw which limits outboard movement of said nut, and said drive tube; and a second stop generally disposed near the inboard end of said drive screw which limits inboard movement of said nut, and said drive tube.