Hospital bed

Abstract: Hospital bed comprising a wheeled base frame (1) and a (patient) support frame (2) carried thereby through the intermediary of a height adjustment mechanism (3), said height adjustment mechanism (3) comprising a λ-shaped linkage that has the lower end of its short leg (20) pivotally connected to the base frame (1) and has the upper end (26) of its longer leg (22) pivotally connected to the support frame (2) at a first location, whereas the lower end (24) of said longer leg (22) is horizontally slidably mounted to the base frame (1), said linkage cooperating with an auxiliary support means that is connected to the support frame (2) at a second location (25), a power source of the expansion and retraction type being provided to operate the height adjustment mechanism, said power source having one end (5) pivotally connected to the base frame (1) and having its other end pivotally connected to the linkage adjacent the central pivot (23) thereof. In accordance with the invention the auxiliary support means is constituted by a link that extends adjacent and parallel to the longer leg (22) of the λ-shaped linkage and forms, together with said longer leg (22), a parallelogram linkage, whereby the lower end (25) of the auxiliary link and that of the longer leg (22) are mounted for a joint sliding movement relative to the base frame (1), and wherein the power source is connected with its lower end (5) to a point of the base frame (1) that is located adjacent and below the location where the lower ends of the longer leg (22) and of the auxiliary link are guided in the base frame (1).

Description: The invention relates to a hospital bed comprising a wheeled base frame and a (patient) support frame carried thereby through the intermediary of a height adjustment mechanism, said height adjustment mechanism being formed by a λ-shaped linkage that has the lower end of its short leg pivotally connected to the base frame and has the upper end of its longer leg pivotally connected to the support frame at a first location, whereas the lower end of said longer leg is horizontally slidably mounted to the base frame, said linkage cooperating with an auxiliary support means that is connected to the support frame at a second location, a power source of the expansion and retraction type being provided to operate the height adjustment mechanism, said power source having one end pivotally connected to the base frame and having its other end pivotally connected to the linkage adjacent the central pivot thereof. Such a hospital bed is known from GB-1,319,593 and GB-1,552,596. The advantage of a λ-shaped linkage is to seen in the relative simple construction as compared with other linkages, which are more complex. In the well-known embodiments according to the above cited references, wherein the lower end of the longer leg is mounted for a horizontal sliding movement relative to the base frame, there is the additional advantage that a height adjustment of the support frame does not involve undesired displacements of the support frame in the horizontal direction. However, the hospital beds according to the above references have a number of disadvantages, which make the advantages of the λ-shaped linkage come out less prominent. For instance in the well-known hospital bed embodiments the power source - which has its upper end pivotally connected to the short leg at an intermediate location-is taking a substantially vertical position. Due to this it is very difficult to combine a relatively wide height adjustment range with a very small minimum height of the support frame and an obstacle-free space under the base frame. For the wider the height adjustment range, the larger the legs of the power source have to be and the larger the minimum height that is taken by the power source in the lowermost position of the support frame. Another disadvantage of the well-known hospital beds concerns the structure of the auxiliary support means. With the hospital bed according to GB-1,319,593 the auxiliary support means is formed by a link which is pivotally connected to the short leg of the λ-shaped linkage and which is normally - i.e. when the support frame is taking a horizontal position - forming an extension of the short leg so that in fact a cross-linkage is formed. The second location at the support frame, where the auxiliary link connects to the support frame, is slidable in the longitudinal direction of the support frame, so that the cross-linkage may vertically extend and retract while the support frame is kept horizontally oriented. In this case, however, the auxiliary link is affecting the compactness of a λ-shaped linkage, because it extends through the space between the support frame and the longer leg of the λ-linkage. With the embodiment according to GB-1,552,596 the auxiliary support means is formed by a piston-cylinder device, which has its upper end pivotally connected at the fixed second location of the support frame and has its lower end pivotally connected to the longer leg of the linkage. This embodiment has also the disadvantage of that according to GB-1,319,593, i.e. that the piston-cylinder device is affecting the compactness of a λ-shaped linkage. Moreover, with each adjustment of the height of the support frame it will also be necessary to adjust the piston-cylinder device (acting as the auxiliary support means in this embodiment) in order to keep the support frame horizontally oriented. Furthermore, this piston-cylinder device is forming another limiting factor in the pursuit of a slightest possible support frame height in the lowermost position. It is an object of the invention to remove the disadvantages of the well-known hospital beds above referred to. According to the invention this aim is achieved in that the auxiliary support means is constituted by a link that extends adjacent and parallel to the longer leg of the λ-shaped linkage and forms, together with said longer leg, a parallelogram linkage, whereby the lower end of the auxiliary link and that of the longer leg are mounted for a joint sliding movement relative to the base frame, and wherein the power source is connected with its lower end to a lower point of the base frame adjacent and below the location where the lower ends of the longer leg and of the auxiliary link are guided in the base frame. By positioning the power source in the manner proposed according to the invention, it may have a relative long length and may thus cover a wide height adjustment range, whereas the power source is taking only a slight height in its retracted position, so that in the lowermost position of the base frame the height of said frame above ground level may be relatively small. Furthermore the power source will - not withstanding its connecting point to the base frame being positioned at a rather low level, no obstacle in the space under the base frame between the wheel pairs. Moreover the dihedral angle between the support frame and the longle λ-leg is substantially free from (auxiliary) links. It is to be noted that EP-A-0341358 discloses a hospital bed, wherein a lifting arm, constituted by a parallelogram linkage, connects the support frame to a base frame. In this case the lifting arm has both of its two lower ends pivotally connected at fixed locations to the base frame. This however has the disadvantage (which does not exist with a λ-linkage) that an adjustment of the height of the support frame will cause the support frame to displace in the horizontal direction as well. Furthermore this well-known construction has the disadvantages which are connected with the use of a substantially vertical position of the power source. The two upper pivot points may be fixed points of the support frame when the hospital bed is desired to be adjustable in the vertical direction only. By using one of the two pivot points (e.g. the uppermost pivot point) has a tilting point for the support frame and connecting the second pivot point through an auxiliary link, e.g. a connecting link having an adjustable length, to the support frame, it would also be possible to place the support frame into an inclined position, the so called Trendelenburg position. The invention will be hereinafter further described by way of example with reference to the accompanying drawing in which: Fig. 1 is a diagrammatic side view of a hospital bed according to the present invention, showing the support frame in its upper and lower horizontal positions and illustrating also the possibility to place the (patient) support frame in an inclined position and fig. 2 is a diagrammatic side view of the bed of fig. 1 in various inclined positions, while the support frame is raised to its uppermost level. In the drawing 1 designates a wheeled base frame, 2 indicates a (patient) support frame and a height adjustment mechanism therebetween is indicated at 3. The power source to be used for operating the height adjustment mechanism 3 is indicated by a dash-dotted line. This power source may be of the expansion-retraction type, such as a hydraulic piston-cylinder device or other telescoping device, which has one end pivotally connected to a low lying point 5 of the base frame adjacent the front or rear pair of castors. The height adjustment mechanism 3 is constituted by a λ-shaped linkage, the short leg 20 of which has its lower end pivotally connected to the base frame 1 about a transverse pivot axis 21. The pivot axis is located adjacent the pair of castors that is located remotely from the pivot point 5. The longer λ-leg of the linkage is a double one and consists of two parallel links 22 of equal length, one of which is pivotally connected with the short leg in an intermediate point 23. The lower ends 24, 25 and the upper ends 26, 27 of the links 22 constitute the angular points of a parallelogram linkage. The lower ends 24 and 25 are mounted in the base frame 1 to perform a joint horizontal sliding movement in the arrow direction. The upper ends 26 and 27 of the links 22 are connected by a coupling plate 16, which is pivotally connected to the support frame 2 about the upper end 26. As is shown in fig. 1 a third pivot 28 of the coupling plate 16 is pivotally connected - through a connecting rod 29 - to a guide piece 30 that is mounted for a sliding movement in the arrow direction along the lower side of the support frame 2. A sliding movement of the guide piece 30 allows the support frame 2 to be placed from the horizontal position into an inclined position, the so-called (anti-) Trendelenburg position. The pivots 27 and 28 may coincide, if desired. In fig. 2 the support frame 2 is shown in three different inclined positions, while it is raised to its highest level. It will be appreciated that the connecting rod-guide piece assembly 29, 30 might be substituted by a connecting rod having an adjustable length, for example of the gas spring type, in which case a fixed pivot could take the place of the slidable guide piece 30. Fig. 1 also illustrates that the height adjustment linkage may be folded up to a link passage that hardly extends beyond the upper side of the base frame 1.

Claims: Hospital bed comprising a wheeled base frame (1) and a (patient) support frame (2) carried thereby through the intermediary of a height adjustment mechanism (3), said height adjustment mechanism (3) comprising a λ-shaped linkage (20,22) that has the lower end of its short leg (20) pivotally connected (21) to the base frame (1) and has the upper end of its longer leg (22) pivotally connected to the support frame (2) at a first location (26), whereas the lower end of said longer leg (22) is horizontally slidably mounted (24) to the base frame (1), said linkage (20,22) cooperating with an auxiliary support means (22) that is connected to the support frame (2) at a second location (27), a power source of the expansion and retraction type being provided to operate the height adjustment mechanism (3), said power source having one end pivotally connected (5) to the base frame (1) and having its other end pivotally connected to the linkage (20,22) adjacent the central pivot (23) thereof, characterized in that the auxiliary support means (22) is constituted by a link (22) that extends adjacent and parallel to the longer leg (22) of the λ-shaped linkage (20,22) and forms, together with said longer leg (22), a parallelogram linkage, whereby the lower end (25) of the auxiliary link (22) and that of the longer leg (22) are mounted (24,25) for a joint sliding movement relative to the base frame (1), and wherein the power source is connected with its lower end to a point (5) of the base frame (1) that is located adjacent and below the location where the lower ends of the longer leg (22) and of the auxiliary link (22) are guided in the base frame (1). A hospital bed according to claim 1, characterized in that the power source has its upper end connected to the upper link (22) of the parallelogram linkage (22) forming the longer λ-leg. A hospital bed according to claims 1-2, characterized in that one of the two upper pivots (26,27) of the parallelogram linkage (22) is acting as a tilting pivot for the support frame (2), whereas the second pivot (27) is connected with a second point of the support frame (2) through a connecting rod (29) of an adjustable length. A hospital bed according to claims 1-2, characterized in that one of the two upper pivots (26,27) of the parallelogram linkage (22) is functioning as a tilting pivot for the support frame (2), whereas the second pivot (27) is connected to a second point of the support frame (2) through a connecting rod (29) of a constant length, said second point (27) being displaceable in the longitudinal direction of the support frame (2).

Inventors: PETERS WOLFRAM JULIUS PAUL, VAN DULLEMEN MARLIES, PETERS, WOLFRAM JULIUS PAUL, VAN DULLEMEN, MARLIES
Applicants: ETESMI J W KOCH B V, ETESMI/J.W. KOCH B.V.
Application year: 1992
Main classification: A61G7
IPC codes: A61G7