Abstract:
A sick-bed includes a bedstead and a bed frame with an adjustable mattress support. The bed frame can be mounted cardanically on the bedstead for the decubitus prophylaxis and can be precessed by means of a drive unit. The bed frame is cardanically suspended on at least three, preferably four lifting drives, which are separate from each other and continuously height-adjustable. The lifting drives are controllable in such a manner that the central normal of the bed frame running through the center of gravity for the bed frame is allowed to carry out a continuous, damped and slow precession movement. Universal joints connecting the lifting drives to the bed frame can allow limited sliding movement therebetween in longitudinal and/or transverse directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of U.S. Ser. No. 10/169,674, filed Jul. 8, 2002, now abandoned, by Albrecht Hörlin for a Sick-Bed. 

   SPECIFICATION 
   The invention relates to a sick-bed, wherein, for the decubitus prophylaxis, a dimensionally stable bed frame as the mattress support, is cardan-mounted on a bedstead, and can be precessed by means of a drive unit. 
   A sick-bed of this kind is known from European Patent Specification EP 799 010 B1. This sick-bed mounts the bed frame centrally on the bedstead in the gravity center of the bed frame by means of an axial ball bearing, the bearing shells of which receive the roller bodies, being precessable relative to each other. This is caused by a wedge disk arranged between the bearing shells and mechanically actuated through a pinion gear. 
   While the decubitus prophylaxis with the known bed leads to extremely satisfying results, the bearing application and the conception of the precession drive of the bed frame on the bedstead have turned out to be problematic. Problems arose, for one, in the nursing sector, where many manipulations and aid to be stored temporarily require a sufficiently free space below the gravity center zone of the bedstead, and for another, are due to the scope of mechanical experiences with said known drive. Thus, said known drive is relatively expensive and heavy, necessitates a comparably complex installation, and requires, and this in turn also with respect to the nursing situation, an arrangement of the mechanical drive directly on the sick-bed. This is often regarded as being disturbing, and namely even then when the drive is not fixed on the bed frame but on the bedstead. 
   SUMMARY OF THE INVENTION 
   Starting from this prior art, the invention is based on the technical problem of further developing the known medical sick-bed for the decubitus prophylaxis in such a manner that the bed center remains unobstructed, that the precession drive is allowed to be configured noiseless, and namely also noiseless over the long term, and is allowed to be configured of a mechanically higher resistance than the strongly loaded bearing shells and the bearing drive known from prior art. 
   The invention solves this problem by means of a sick-bed, the bed frame of which is not mounted on roller bearings but on at least three lifting drives height-adjustable in a continuous and arbitrarily reversible manner, the operation thereof being arranged coordinate in such a way that the initially mentioned precession data are allowed to be set without problems and, above all, without noise. With this configuration of the bearing and the precession drive, a change of the precession frequency, as well as of the precession amplitude can in particular be achieved in a considerably simpler manner than it is possible with the mechanical roller bearing according to the prior art. According to the invention, it is moreover possible to mount the bed frame height-adjustable and inclination-adjustable with respect to its stationary position. 
   Preferably, four continuously height-adjustable lifting drives vertically fixed to the bedstead are used, each carrying the bed frame in the zone of its four corners. This articulation to the bed frame is thereby configured cardanically, for example by means of a ball-and-socket joint or a cardanic joint. 
   For achieving a highest possible mobility of the sick bed intended for the decubitus prophylaxis, the continuously height-adjustable lifting drives according to an embodiment of the invention are configured as an adjustable electromotive telescopic lifting column. 
   For creating the desired position of the bed frame, e.g., for the simple static height adjustment or the inclination angle adjustment or even for the dynamically oscillating or precessional motion, threaded spindles are provided for each telescopic lifting column. 
   The number and height of the telescoping spindles thereby corresponds to the amount of the maximally required height adjustment or, with respect to the mobility of the bed, to the amount of the maximally required amplitude. 
   The telescopic lifting column is realized in such a manner that within a cylindrical outer sleeve, a working rod is disposed, within which, for example, two threaded spindles with the corresponding spindle nuts are provided intended for a two-fold height adjustment of the lifting columns. 
   The height adjustment itself ensues by coupling said spindles to an electronically driven electric motor via a gear, for example a planetary gear, and via corresponding toothed wheels. In particular, each lifting spindle is thereby assigned an electric motor of its own. 
   For the height adjustment furthermore, either the electric motor is configured as a reversing motor or the gear is configured as a reversing gear. Thereby, the drive unit for the telescopic lifting column is in particular conceived in such a manner that it allows for a mobile energy supply. Moreover, said drive unit should feature dimensions as small as possible relative to the size of the telescopic lifting column itself. 
   With respect to the use in a sick-room, moreover, only electric motors as silent as possible should be used as drive units. Also, a particularly effective acoustic decoupling, at least a sound absorption has in addition to be provided for, preventing a transmission of structure-borne noise from the drive unit into the bedstead and the bed frame, as well as an emission of airborne noise from the drive unit into the sick-room. 
   The working rod of the telescopic lifting column, which rod is guided within the cylindrical sleeve, comprises on its end an articulation ball head forming a cardanic ball-and-socket joint with a corresponding ball socket of the bed frame, or is articulated to the bed frame via a cardanic universal joint. In these bearing locations, the means for the absorption of the structure-borne noise or for the decoupling of the structure-borne noise are in particular arranged. 
   If the telescopic lifting column is supposed to create movements with a high precession frequency and maximum amplitude, then the cardanic suspension has to be realized preferably via universal joints. 
   According to a second embodiment of the invention, the height-adjustable lifting drives are configured as a hydraulically integrated constructional unit with a hydraulic working cylinder, and namely preferably so that each of the working cylinders is equipped with a pump of its own and with a central control valve of its own having a closed hydraulic circuit. The hydraulic compressors used thereby are preferably acted upon electrically and are controlled electronically. With the use and installation of electric energy storage in the bedstead, such a prophylaxis bed is mobile even for a longer period of time and can be used independent of an external supply. 
   If, however, an absolute silence of the precession drive has to be set, and the capacity of a mobile displacement of the prophylaxis bed is of secondary importance, then the hydraulic working cylinders are configured without an integrated compressor and without an integrated valve, instead, all hydraulic working cylinders are connected to a central hydraulic multiple valve which can be controlled in a programmed manner, which multiple valve is connected to a common external pressure supply, for example, to a hydraulic compressor standing isolated in the next room, or to an already existing central hydraulic pressure supply line. The hydraulic working cylinders themselves, which cause the precession of the bed frame, work without any noise development, and thereby work continuously and vibrationless to the highest degree. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many objects and advantages of this invention will be apparent to those skilled in the art when this specification is read in conjunction with the attached drawings wherein like reference numerals are applied to like elements and wherein: 
       FIG. 1  is a schematic perspective representation of a sick-bed exhibiting features of the invention; 
       FIG. 2  is schematic illustration of the precession movement according to the present invention; 
       FIG. 3  is a schematic illustration of an adjustable support surface according to the present invention; 
       FIG. 4  is a plan view of a longitudinally adjustable universal joint according to the present invention; 
       FIG. 5  is a plan view of a universal joint according to the present invention; 
       FIG. 6  is a plan view of a bi-axially adjustable universal joint according to the present invention; 
       FIG. 7  is a plan view of a transversely adjustable universal joint according to the present invention; 
       FIG. 8  is a partial cross-sectional view taken along the line  8 - 8  of  FIG. 4 ; and 
       FIG. 9  is a top view of the universal joint of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The sick-bed shown in  FIG. 1  is comprised of a bedstead I and a rigid and dimensionally stable bed frame  2 . For convenience, it will be useful to refer to longitudinal and transverse directions on the bed frame  2 . The bed frame  2  will be considered to have a longitudinal direction extending between a first end  41  and a second end  43  of the bed frame  2  and being generally parallel to side rails  40  of the bed frame. In addition, a transverse direction extends between the side rails  40  of the bed frame  2  generally perpendicularly to the longitudinal direction. 
   The bedstead  1  is configured substantially rectangular, and is so dimensioned that it remains just slightly within the outer dimensions of bed frame  2 . By means of four wheels  3  articulated to cantilevers  4  of bedstead  1 , the sick-bed is designed to be movable. A line  9  normal to a plane of the bed frame  2  also passes through the center of gravity for the bed frame  2 . 
   The bed frame  2  is constructed and arranged relative to the bedstead  1  so that a plane  10  (see  FIG. 2 ) fixed to the bed frame  2  having the normal line  9  (i.e., perpendicular to the plane  10 ) moves in a manner that is best described as precession. That movement is effected by controlled movement of the corners of the plane  10  upwardly and downwardly as indicated by the arrows  12 ,  14 , and  16 . The fourth corner also can move vertically but the movement arrows under the plane  10  at that corner would be obscured by the plane  10 . Movement of the plane  10  as well as the bed frame  2  relative to the bedstead  1  may be accomplished by a plurality of hydraulic working cylinders  5  (see  FIG. 1 ) each of which is positioned in the region around a corner of the bed frame  2 . 
   The concerted action of the working cylinders  5  is such that the normal line  9  (see  FIG. 2 ) moves along an imaginary conical surface  22 . Depending upon the particular location of the center of movement, the conical surface  22  could be a frustoconical surface. In any event, as the bed frame  2  moves, the normal line  9  moves in the direction of the arrow  20  and sweeps along the imaginary conical surface  22 . Stated differently, the normal line  9  functions as the generatrix of the conical surface  22 . 
   For achieving an optimum decubitus prophylaxis, a precession frequency for the plane  10  is preferably in the range of between 6 and 36°/min, with a maximum amplitude in the range of between 3 and 10 cm. The maximum amplitude is measured relative to the maximum vertical excursion from the horizontal of a patient of average size laid on the bed. Amplitude adjustments are contemplated to accommodate the actual size of any patient, but the preferred maximum amplitude range is as indicated. For convenience, the amplitude measurement may be taken at the corners of the bed frame  2 . For purposes of this invention, precession frequency refers to the angular movement per unit time of the normal line  9  along the conical surface  22  in the direction of the arrow  22  around the axis of that conical surface  22 . These ranges of precession frequency and precession amplitude have been found to be suitable to accomplish optimal decubitus prophylaxis. 
   It is also within the contemplation of this invention that the bed frame  2  have an adjustable mechanism  30  (see  FIG. 3 ) operable to raise and lower a portion of a mattress supporting the region of a patient&#39;s upper body, and operable to raise and lower another portion of a mattress typically supporting the region of a patient&#39;s upper and lower legs and feet. For example, an upper body panel  32  may be hingedly connected to the bed frame  2  so as to be movable between a first flat position  32 ′ which is generally coplanar with the top of the bed frame  2  and a second elevated position where one end of the upper body panel  32  is elevated above the bed frame. In addition, an upper leg panel  36  can be hingedly connected to the bed frame  2  and to a lower leg panel  38 . An edge of the lower leg panel  38  can be arranged to slide along the bed frame  2  when the hinged edged is elevated. At the same time, the upper leg panel  36  is elevated so that the panels  36 ,  38  support a patient&#39;s legs in a flexed position. If desired, side panels (not shown) extending vertically along the side edges of one or more of the panels  32 ,  34 ,  26 ,  28  may be provided to help prevent a patient from inadvertently moving beyond the peripheral edge of the bed frame  2 . To articulate the upper body panel  32  and the upper and lower leg panels  36 ,  38 , suitable conventional power mechanisms may be provided. Typically, such mechanisms may be hydraulically, pneumatically, or electrically driven. Furthermore, suitable conventional operational controls may be provided that are patient accessible. 
   Turning now to the system for operating the precession of the bed frame  2  relative to the bedstead  1 , a continuously height-adjustable telescopic lifting columns  5  is fixed In the zone or region of each of the four outer corners of the bedstead  1 . All of the four telescopic lifting columns are realized identical. Each of the height-adjustable columns  5  is vertically fixed to the bed frame in a rigid and stationary manner, hence, for example, welded or screwed with same. On the head of each working rod of each telescopic lifting column  5 , an articulation ball head may be provided which forms a cardanic ball-and-socket joint, a corresponding ball socket being attached to the bed frame  2 . The lifting columns are the sole support for the bed frame so that the region under the bed frame  2  is open and essentially unobstructed. 
   The cardanic joint  6  may also be configured as a universal joint. In any event, the cardanic joints  6  are constructed and arranged so as to be releasable from the head of the working rod of the telescopic lifting column  5 . In this manner, the bed frame  2  can be moved after an adjusting manipulation even without the bedstead and its lifting drives. Thus, the bed frame  2  can be transferred, for example during emergency cases or situations, onto a secondary undercarriage. 
   Depending upon the dimensions of the bed frame  2  and the precession amplitude ranges being provided, it may be desirable to arrange the cardanic connection between the lifting columns  5  and the bed frame  2  so that lateral movement of the bed frame  2  can occur relative to at least some of the lifting columns  5 . This connection arrangement may, for example, be desired when a full size patient bed is to be mounted and where the upper end of the precession amplitude range is to be accommodated. 
   In such situations, a universal joint arrangement may be provided for each of the lifting cylinders  5  (see  FIG. 1 ). One of the universal joints  6   a  may be constructed and arranged so that the bed frame  2  is not permitted to move in either the longitudinal or transverse direction relative to the corresponding lifting cylinder. A second universal joint  6   b  at one corner of the bed frame adjacent to the first universal joint  6   a  may be constructed and arranged to accommodate longitudinal movement of the bed frame  2  relative to the corresponding lifting cylinder to accommodate longitudinal sliding associated with different elevations of the lifting cylinders corresponding to the universal joints  6   a  and  6   b . A third universal joint  6   d  at another corner of the bed frame  2  adjacent to the first universal joint  6   a  may be constructed and arranged to accommodate transverse movement of the bed frame  2  relative to the corresponding lifting cylinder to accommodate transverse sliding associated with different elevations of the lifting cylinders corresponding to the universal joints  6   a  and  6   d . A fourth universal joint  6   c  at an opposite corner of the bed frame  2  may be constructed and arranged to accommodate both longitudinal and transverse movement of the bed frame  2  relative to its corresponding lifting cylinder to accommodate both transverse and longitudinal sliding associated with different elevations between the lifting cylinders corresponding to the universal joints  6   a  and  6   c.    
   Turning now to  FIG. 4 , details of a preferred embodiment of the longitudinally slidable universal joint  6   b  are shown. The universal joint  6   b  includes cap  44  adapted to be attached to the upper end of the corresponding lifting cylinder by one or more suitable conventional threaded fasteners  46 . A pair of generally parallel arms  48 ,  50  extends from the side rail  40  in the transverse direction toward the central region of the bed frame  2 . Each arm  48 ,  50  carries a corresponding generally cylindrical axle pin  52 ,  54 . The axle pins  52 ,  54  are coaxially aligned and generally parallel to the side rail  40 . The axle pins  52 ,  54  may be threadably connected to the corresponding arms so as to be removable. In addition, the axle pins  52 ,  54  connect with a generally rectangular collar  70  such that the collar can rotate about the aligned axle pins  52 ,  54  relative to the arms  48 ,  50  and can slide longitudinally along the axle pins  52 ,  54  between those arms. Thus, the collar  70  is spaced from the arms  48 ,  50 , at the gaps  56 ,  58 , but the relative size of the gaps  56 ,  58  is selected to accommodate any longitudinal movement that may be needed as the bed frame  2  precesses. 
   The cap  44  includes a pair of axle pins  60 ,  62  which are coaxially aligned and extend on opposite sides of the cap  44  to connect the cap  44  with the collar  70 . The axle pins  60 ,  62  are coaxially aligned and extend in the transverse direction of the bed frame. Each axle pin  60 ,  62  includes a bushing or radial step  64 ,  66  having a larger lateral dimension than the end of the pin so that the collar  70  can rotate about the pins  60 ,  62  but is constrained from substantial sliding movement along the axle pins  60 ,  62 . The universal joint  6   b  thus permits sliding movement in the direction of arrow  72  while otherwise permitting angular movement between the corresponding lifting cylinder  5  and the bed frame  2  (see  FIGS. 8 and 9 ). 
   Turning now to  FIG. 5 , details of a preferred embodiment of the universal joint  6   a  are shown. The universal joint  6   a  includes cap  80  adapted to be attached to the upper end of the corresponding lifting cylinder by one or more suitable conventional threaded fasteners  46 . A pair of generally parallel arms  84 ,  86  extend from the side rail  40  in the transverse direction toward the central region of the bed frame  2 . Each arm  84 ,  86  carries a corresponding generally cylindrical axle pin  94 ,  96 . The axle pins  92 ,  94  are coaxially aligned and generally parallel to the side rail  40  and are preferably parallel to the axle pins  52 ,  54  of universal joint  6   b . The axle pins  92 ,  94  may be threadably connected to the corresponding arms so as to be removable. In addition, the axle pins  92 ,  94  connect with a generally rectangular collar  82  such that the collar  82  can rotate about the aligned axle pins  92 ,  94  relative to the arms  48 ,  50  but cannot slide longitudinally along the axle pins  92 ,  94  between those arms. Thus, the collar  70  and the arms  48 ,  50  do not accommodate any substantial longitudinal movement when the bed frame  2  precesses. 
   The cap  80  includes a pair of axle pins  88 ,  90  which are coaxially aligned and extend on opposite sides of the cap  80  to connect the cap  80  with the collar  82 . The axle pins  88 ,  90  are coaxially aligned and extend in the transverse direction of the bed frame. Each axle pin  88 ,  90  includes a bushing or radial step  96 ,  98  having a larger lateral dimension larger than the end of the pin so that the collar  82  can rotate about the pins  88 ,  90  but is constrained from substantial sliding movement along the axle pins  88 ,  90 . The universal joint  6   a  thus does not permit substantial sliding movement in either the longitudinal direction or the transverse direction. 
   Turning now to  FIG. 6 , details are shown of a preferred embodiment for the universal joint  6   c  which accommodates both longitudinal and transverse sliding of the bed frame  2  relative to the corresponding lifting cylinder. The universal joint  6   c  includes cap  100  adapted to be attached to the upper end of the corresponding lifting cylinder by one or more suitable conventional threaded fasteners. A pair of generally parallel arms  102 ,  104  extends from the side rail  40  in the transverse direction toward the central region of the bed frame  2 . Each arm  102 ,  104  carries a corresponding generally cylindrical axle pin  112 ,  114 . The axle pins  112 , 114  are coaxially aligned and generally parallel to the side rail  40 . The axle pins  112 ,  114  may be threadably connected to the corresponding arms so as to be removable. In addition, the axle pins  112 ,  114  connect with a generally rectangular collar  106  such that the collar can rotate about the aligned axle pins  112 ,  114  relative to the arms  102 ,  104  and can slide longitudinally along the axle pins  112 , 114  between those arms. Thus, the collar  106  is spaced from the arms  102 ,  104  at the gaps  116 ,  118 , but the relative size of the gaps  116 ,  118  is selected to accommodate any longitudinal movement that may be needed as the bed frame  2  precesses. 
   The cap  100  includes a pair of axle pins  108 ,  110  which are coaxially aligned and extend on opposite sides of the cap  100  to connect the cap  100  with the collar  106 . The axle pins  108 ,  110  are coaxially aligned and extend in the transverse direction of the bed frame  2  and are generally parallel to the axle pins  88 ,  90  of universal joint  6   a . The collar  70  can rotate about the pins  108 ,  110  but is not constrained from substantial sliding movement along the axle pins  60 ,  62 . The universal joint  6   c  thus permits sliding movement in the direction of arrow  124  while otherwise permitting angular movement between the corresponding lifting cylinder  5  and the bed frame  2 . 
   Details of the universal joint  6   d , which accommodates transverse sliding, are shown in  FIG. 7 . The universal joint  6   d  includes a cap  130  adapted to be attached to the upper end of the corresponding lifting cylinder by one or more suitable conventional threaded fasteners. A pair of generally parallel arms  132 ,  144  extends from the side rail  40  in the transverse direction toward the central region of the bed frame  2 . Each arm  132 ,  134  carries a corresponding generally cylindrical axle pin  138 ,  140 . The axle pins  138 ,  140  are coaxially aligned and generally parallel to the side rail  40 . The axle pins  138 ,  140  may be threadably connected to the corresponding arms so as to be removable. In addition, the axle pins  138 ,  140  connect with a generally rectangular collar  136  such that the collar can rotate about the aligned axle pins  138 ,  140  relative to the arms  132 ,  134  but such that the collar  136  cannot slide longitudinally along the axle pins  138 , 140  between those arms. 
   The cap  130  includes a pair of axle pins  142 ,  144  which are coaxially aligned and extend on opposite sides of the cap  130  to connect the cap  130  with the collar  136 . The axle pins  142 ,  144  are coaxially aligned and extend in the transverse direction of the bed frame. The collar  136  can rotate about the pins  142 ,  144  and can slide along the axle pins  142 ,  144 . The universal joint  6   d  thus permits sliding movement in the direction of arrow  150  while otherwise permitting angular movement between the corresponding lifting cylinder and the bed frame. 
   If desired, the universal joint  6   c , which accommodates both longitudinal and transverse movement, can be substituted for universal joint  6   b  (accommodating longitudinal movement) and/or universal joint  6   d  (accommodating transverse movement). Such substitutions might be preferred for example to reduce the number of parts for the sick bed. 
   The adjustable lifting column  5  ( FIG. 1 ) is comprised of a number of telescoping spindles, which are movable through a motor and a corresponding gear, either the motor being configured as a reversing motor or, alternatively, the gear being configured as a reversing gear. 
   For the operation of the telescoping spindles, only the driving current for the motor and the voltage for the electronic signal unit are still required. Thereby, these elements could be designed so far miniaturized, due to the little power necessary, that in the way outlined in  FIG. 1 , an electric storage  7  and an electronic processor  8  are integrated in the bedstead  1  for all four of the telescopic columns in common. 
   The sick-bed for the decubitus prophylaxis described here, is characterized by an immediately responding spindle drive and a simple mobile energy supply, whereby a large number of accessories can be dispensed with, which in turn signifies a weight saving. 
   In operation, the telescopic lifting columns are controllable in such a manner that the central normal  9  of the bed frame running through the gravity center of the bed frame  2 , carries out a continuous and slow precession movement without perceptible increments. 
   It will now be apparent to those skilled in the art that a new and improved sick-bed for avoiding and/or treating decubitis has been described. It will also be apparent to those skilled in the art that numerous modifications, variations, substitutions, and equivalents exist for features of the invention. Accordingly, it is expressly intended that all such modifications, variations, substitutions, and equivalents that fall within the spirit and scope of the claims should be encompassed by those claims.