Patients residing in long-term care facilities such as nursing homes and rehabilitation facilities usually require beds that include movable head end and foot end sections of the sleep surface. The sleep surface and related components are attached to a frame which provides a rigid supporting structure. Also attached to the frame are the components for elevating or tilting the bed frame relative to the support surface. These beds typically utilize multiple manual crank devices or electric actuators to provide separate elevating movement of the head end and foot end sections of the sleep surface and also to raise, lower or tilt the entire frame and sleep surface relative to the support surface.
The present invention relates to a bed incorporating a leg assembly coupled to a support link assembly by a joint, the joint comprised of a slot having at least two paths. Another aspect of the present invention relates to a length that automatically varies as the support link assembly moves relative to the leg assembly.
A long-term care bed 10 as illustrated in
The elevation of the frame 40 above a support surface can be adjusted or readjusted by means of two leg assemblies 30. Caster assemblies 20 are attached for pivotal movement to the lower outside ends of each leg assembly 30. Alternatively, wheels or fixed ground engaging elements can be used in place of caster assemblies 20. As will be described, the two leg assemblies 30 work in conjunction with other bed lift mechanism components to achieve zero or substantially zero horizontal or lateral movement of the caster assemblies 20 relative to the support surface when changing the elevation of the frame 40 above the support surface. It should be noted that the frame 40 can be tilted relative to the support surface to achieve a therapeutically desired Trendelenburg position.
Referring to
In the present embodiment as shown in
The main portion of leg assembly 30 is comprised of caster tube 32 and legs 34. Legs 34 are positioned laterally apart and substantially parallel to each other and joined at their lower ends to cross tube 32 to form a substantially “U-shaped” structure. Caster assemblies 20 are pivotally attached to the outer ends of cross tube 32 and allow leg assembly 30 to rotate about the longitudinal axis of cross tube 32 designated as pivot axis D. Legs 34 are metal tubing with any of a variety of cross-sectional shapes such as round, square, rectangular or the like and can be straight as shown or incorporate curved regions.
Referring to
Pins 70 and 72 are preferably metal and cylindrical in shape and are joined to leg 34 so that their longitudinal axes project substantially perpendicular to the inside surface of leg 34. The longitudinal axes of pins 70 on opposing legs 34 are aligned so as to be substantially coaxial. So constructed, the axes of pins 70 forms or approximates a pivot axis spanning laterally across leg assembly 30 and is designated as pivot axis C. Likewise, the longitudinal axes of pins 72 on opposing legs 34 are aligned so as to be substantially coaxial. Although it is shown that pins 70 and 72 project inwardly toward the longitudinal center line of bed 10, the mechanism can be rearranged so that pins 70 and 72 project perpendicularly outward from leg 34. Low friction rollers 74 and 76 are installed on pins 70 and 72 respectively for engaging with and following the contour of a slot 66 described later in more detail. Rollers 74 and 76 can be a conventional bushing, bearing or similar device and be constructed of various metal and plastic materials. Rollers 74 and 76 are retained on pins 70 and 72 respectively by any conventional retaining means such as a screw, nut, clip or the like.
Support link 60 is comprised of two links 62, cross member 64 and bracket 68. Links 62 are positioned laterally apart and substantially parallel to each other and are joined at their lower ends to cross member 64 to form a substantially “U-shaped” structure. The upper end of each link 62 contains a through hole for pivotal attachment to brackets 54 by means of a bolt, pin or the like. Brackets 54 are formed from metal as one piece or by combining two pieces and are mounted by any conventional means to rails 42 and/or cross rails 44. The through holes in brackets 54 at each end of bed frame 40 are aligned so as to be coaxial and thus create pivot axis A. These pivoting joints may also employ conventional bushings or bearings in the link 62 holes and/or the bracket 54 holes to reduce friction and/or noise.
Cross member 64 enables both links 62 to move in unison and also allow for one actuator 90 to be used for each end of bed 10. Cross member 64 is made from metal and can have a cross-sectional shape such as circular, square, rectangular, etc. Bracket 68 is formed or cast from metal as a separate component or can be integrated with cross member 64 into one larger casting. Bracket 68 is centrally located on cross member 64 and projects towards the center of bed 10.
Links 62 are mirror images of each other about the bed 10 longitudinal centerline. Each link 62 can be one piece or a multi-piece assembly made from metal and formed by any conventional fabrication process such as machining, stamping, laser cutting, welding, etc. or cast and machined by any well-known conventional processes. At the lower end of link 62 is slot 66 depicted in
The behavior of the bed lift mechanism is dependent on the shape of slot 66 and can be configured such that the caster assemblies 20 are motionless relative to support surface 5 during raising or lowering of the frame 40 above support surface 5, or in specific situations where movement of the caster assemblies 20 is desired, the slot 66 shape can be tailored to achieve the desired movement. It is understood that alternate arrangements of the slot 66 shape may cause various desired forms of frame 40 movement. For example, alternate slot 66 shapes may include causing frame 40 to initially rise slowly away from the support surface 5 to minimize loading on the actuator 90 or to minimize any jolting movement to the occupant. Yet another alternate slot 66 shape may cause the frame 40 to translate horizontally a short distance away from an adjacent object such as a wall or furniture before rising vertically. Other movements are also possible including combinations of the preceding.
Referring back to
Actuator 90 positions support link 60 which in turn determines the position and motion of leg assembly 30. The extension in length of actuator 90 rotates support link 60 counterclockwise about pivot axis A as viewed in
Leg assembly 30 is pivotally and slideably coupled to support link 60 at pivot axis C by the arrangement of the roller 74 in the lower path of slot 66 and roller 76 in the upper path of slot 66. Roller 74 contacts the left side surface of the lower path of slot 66 while roller 76 contacts the upper surface of the upper path of slot 66. The upper path is configured in such a manner that the distance from any point along the upper surface to pivot axis C could vary from any other point. Dimension L defines the variable radial distance between pivot axis C and pivot axis A. While roller 74 at pivot axis C provides a sliding pivotal connection between leg assembly 30 and support link 60, roller 76 bearing against the upper surface of the upper path of slot 66 controls the variable length L. The rotation of leg assembly 30 relative to support link 60 causes roller 76 to follow the upper path of slot 66, which because of its shape, automatically changes the distance from pivot axis A to the contact point between roller 76 and the upper surface of the upper path. This varying distance causes roller 74 to translate longitudinally in the lower path of slot 66 and, in effect, constantly change the length L thereby providing a variable length connection between pivot axis A and pivot axis C. In one embodiment, length L changes by approximately one inch as frame 40 is elevated from its lowest position relative to the support surface to its fully elevated position.
To illustrate how frame 40 is raised relative to support surface 5, it will be assumed that frame 40 is being raised substantially horizontal and both leg assemblies 30 perform in the identical manner, therefore only the operation of one combination of leg assembly 30 and support link 60 will be described.
Lowering of frame 40 is accomplished by commanding the actuator to contract in length. This reverses the motion of all related components such that they follow the same path in moving to a lower vertical position. It is understood that frame 40 can be vertically positioned at any level within the range from its lowest position relative to support surface 5 to its highest position and can be subsequently repositioned in either direction as desired.
AB1>AB2>AB3
AC1<AC2>AC3
In an alternate embodiment, the bed lift mechanism can be configured such that support link 60 has only one link 62 to support the leg assembly 30. A single link 62 with slot 66 is positioned approximately at the longitudinal center line of bed 10. This single link 62 would be coupled to a single arrangement of rollers 74 and 76 located on a cross tube spanning between legs 34 of the leg assembly 30. The actuator 90 is pivotally coupled to either the support link 60 or the cross tube on leg assembly 30. The single link 62 would provide the identical lifting function as the two link 62 arrangement described previously, but may require other modifications or additional elements to keep the mechanism aligned and functioning properly. For instance, rollers 74 and 76 may need to be specified with a higher load rating to accommodate the increased loading that a single support link would carry. Also, rollers 74 and 76 may require some alignment features to mate consistently with slot 66 in link 62.
In another alternate embodiment, it may be desirable to raise and lower the frame 40 using only one actuator 90. In such a case, actuator 90 is connected to both leg assemblies 30 or to both support links 60 by appropriate cables, levers, rack and pinion gearing, or any other well known linkage mechanism. Actuator 90 is then able to reposition both ends of the bed lift mechanism simultaneously.
While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the specification to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, individual components can be combined, assemblies can be divided into separate components or components can be rearranged without affecting the operation. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.
This application claims the benefit of U.S. provisional patent application Ser. No. 60/998,287 for BED LIFT MECHANISM filed Oct. 10, 2007, the entire disclosure of which is fully incorporated herein by reference.
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Number | Date | Country | |
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20090094747 A1 | Apr 2009 | US |
Number | Date | Country | |
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60998287 | Oct 2007 | US |