US 5,343,581 A · Housing and drive mechanism for screw lift of hospital bed

Abstract

A drive mechanism for a hospital bed effects relative vertical movement of a base and a patient litter. The drive mechanism includes spaced, telescoping threaded screw assemblies, which are driven by a single electric motor through a train of gears having helical teeth oriented to offset inherent frictional forces of the screw assemblies. A support for the motor and a component of the drive train are made of electrically nonconductive materials to electrically isolate the motor, and are arranged to damp vibrations produced by the motor. Two coiled electrical cords extend between the base and patient litter, and are each received in a recess in the patient litter when the patient litter is adjacent the base. A sensor arrangement provides an electrical signal indicative of the relative vertical positions of the patient litter and base, and a manual drive arrangement is provided to permit the gear train to be manually driven.

Claims25

Dependent claims

An apparatus comprising:

first and second members and lift means cooperable with said first and second members for effecting relative vertical movement thereof, said lift means including a vertically extending threaded member, a motor, and drive train means for effecting vertical movement of said threaded member in response to operation of said motor, said drive train means including noise reducing means for reducing noise generated by said drive train means, said noise reducing means including first and second gears having engaging helical teeth;
wherein said drive train means includes a further vertically extending threaded member, a drive gear rotatably driven by said motor, two idler gears each rotatably driven by said drive gear, and two output gears each driven by a respective said idler gear and drivingly engaged with a respective said threaded member, each of said drive gear, said idler gears and said output gears having helical teeth, one of said idler gears and the output gear engaged therewith being said first and second gears.

An apparatus comprising:

first and second members and lift means for effecting relative vertical movement of said first and second members, said lift means including a vertically extending threaded member, a rotatably supported output member, and means for effecting axial movement of said threaded member in response to rotation of said output member, said output member being urged in a first axial direction in response to axial movement of said member, and including drive means for effecting rotation of said output member and for simultaneously urging said output member in a second axial direction opposite said first axial direction.

An apparatus comprising:

first and second members and lift means for effecting relative vertical movement of said first and second members, said lift means including an elongate cylindrical member having external threads thereon and including a tubular nut member disposed in an opening in a further member and having internal threads which engage said external threads of said cylindrical member, said opening in said further member having at an upper end thereof an enlarged portion and said nut member having adjacent an upper end thereof a collar portion which is disposed in said enlarged portion of said opening, said collar portion and said enlarged portion having means for preventing rotation of said nut member relative to said further member, and including means for effecting relative rotation between said cylindrical member and said further member to thereby effect vertical movement of said cylindrical member relative to said nut member and said further member.

An apparatus comprising:

first and second members and lift means for effecting relative vertical movement of said first and second members, said lift means including a housing provided on said first member and having a threaded part thereon, a vertically extending cylindrical member coupled to said second member and having external threads which engage said threaded part, a selectively actuable motor, and drive train means for effecting relative rotation between said cylindrical member and said threaded part in response to operation of said motor and a motor support part supported on said housing and made of an electrically nonconductive material, said motor being supported on said motor support part, and said drive train means including an electrically nonconductive coupling part which electrically isolates said motor from said drive train means, wherein said motor support part is a horizontally extending plate which is coupled to said housing at spaced predetermined locations, said motor being supported on said plate at a further location thereon spaced from said predetermined locations and being oriented so that a rotatably supported output shaft thereof extends approximately perpendicular to said plate, and wherein said drive train means includes a driver mounted on said shaft of said motor and a further part cooperating with said driver so as to be held against rotation with respect thereto but so as to be capable of limited axial movement with respect thereto.

Dependencies are inferred from the claim text.

Housing and drive mechanism for screw lift of hospital bed

Life of this patent

Housing and drive mechanism for screw lift of hospital bed

Life of this patent

Abstract

Claims25