HK1146381B - Lifting column for treatment tables, hospital-and care beds - Google Patents

Description

Lifting column for treatment tables, hospitals and nursing beds

Technical Field

The present invention relates to lifting columns for treatment tables, hospitals and nursing.

Background

Hospital beds comprise an upper frame connected to a support for a mattress and a lower frame equipped with drive wheels. Just as the upper frame may be tilted about a lateral axis (Trendelenburg position), the upper frame may be raised and lowered in its entirety to be set at a desired height above the ground. The lifting and lowering of the upper frame may be achieved in various ways, for example the upper frame is connected to the lower frame by a linear actuator driven scissor mechanism, as described in EP 498111B 2 j. Another way is to equip the bed with 4 telescopic legs, e.g. DE 29800015U 1 john. More specifically, the invention departs from the type of bed in which the upper frame is supported by a single telescopic column at each end and these columns are fixed to the longitudinal central axis of the lower frame. A construction of this type is shown, for example, in EP 984018A 2 Linet Spol SRO and DE 29804283 Dewert Antriebs-und Systemtechnik GmbH & Co.

The strength and stiffness requirements of these columns are very high. In addition to the effect of axial forces, the lifting column must also be able to withstand large torque loads, typically because one or more persons sit on the edge of the bed. Furthermore, this has the consequence that torque loads also occur on the column which is located in the longitudinal direction of the bed. As the upper frame tilts, the head-foot height adjustment (Trendelenburg-adjustment) also generates a torque, which also results in a force on the column located in the longitudinal direction of the bed. Horizontal forces also occur on the column when the bed is moved by manually pushing/pulling the head and/or foot pedals of the bed.

WO 01/74198 Al Linak discloses a lifting column that is able to withstand the different considerable forces and torques that occur on such a bed structure. The lifting column includes a surrounding telescoping housing having three members with a three member telescoping guide received in either side, each having a lower member, a middle member and an outermost member. The two intermediate members and the two outermost members are interconnected by a yoke. The intermediate member is extended by a linear actuator located between the two guides and is connected to the bottom plate and to the yoke between the two intermediate members. In order to extend the outermost member, each side is equipped with a chain drive, wherein a chain is arranged around two pulleys. One of the chain lengths is connected to the lower member, while the other chain length has a bar connected to the yoke for the two outermost members. The top sprockets are interconnected and fixed to the two intermediate members. This causes the outermost member to project in synchronism with the projection of the intermediate member. As can be appreciated, the above-described structure is bulky and complex, and therefore relatively expensive to manufacture.

Disclosure of Invention

The object of the invention is to simplify the construction of such a column.

According to the invention, the above object is achieved by a construction in which the three members of the housing are configured as telescopic guides, i.e. a single body element comprising one chain with a plurality of chain wheels, both chain lengths with a drive rod, a spindle positioned in the cross section of the body element, and a spindle nut fixed to the body element. A compact construction is thereby achieved, since there is only one guide which at the same time also functions as a housing. Furthermore, just as the actuator is integrated with the body element, there is only one chain. It is also easy to produce, as only some of the parts form part of the column.

In one embodiment, the body member has at least one separate end piece to which one of the sprockets is mounted. In a preferred embodiment, the body element has a separate end piece at each end, and the sprockets are mounted on the end pieces. This eases the assembly process and provides the possibility for various configurations. The end pieces may be identical, so that only one mold is required to manufacture the end pieces.

In one embodiment, an adjustment element is disposed between the end piece and the body element for adjusting the length between the two sprockets. It facilitates the assembly process and at the same time provides the possibility of tightening the sprocket. The adjusting element is preferably configured as a wedge element.

The spindle nut may be formed directly on the body element, but it has proved advantageous to use a separate spindle nut, preferably embedded in one of the end pieces. In this way, a spindle nut known per se can be used, while the manufacture of the body element is simplified.

When the main shaft and the chain are laterally separated from each other, a torque is generated on the main shaft which can break the main shaft. In an embodiment, this is avoided in that one of the end pieces is connected to the body element via a tilting shaft, by which means torque forces are not transmitted to the main shaft.

In order to guide the body element in the lateral direction, in one embodiment the body element rests on the inner side of the intermediate telescopic member. Conveniently, the body element is supported by a recess in a longitudinal rib in the intermediate telescopic member.

It has proven to be suitable to use motors having a length/width ratio of less than 1. This makes it possible to provide an elongated lifting column.

In one embodiment, the housing for the drive (gear) and bearings of the spindle is fixed to the front end of the motor so that it is mounted directly in the column as a unit.

The length/width ratio of the motor described above makes it possible to use a worm drive and still achieve a slim column. The worm drive is attractive due to the high gear ratio (gearing) and quiet nature. A worm wheel is mounted on one end of the main shaft, and a worm is configured as an extension of the motor shaft. The motor is then positioned perpendicular to the spindle. When using the usual motor types, it is necessary to place the motor parallel to the main shaft, which results in a more complex transmission structure.

In one embodiment, the housing has a holder in the form of a pocket in which an elongated printed circuit having at least one end stop switch can be secured. Thus, the printed circuit is parallel to the spindle and at the same time easy to assemble, since it can be fixed to the motor unit before insertion into the post.

The free ends of the elongated printed circuit are conveniently equipped with controls for vertical rods on the lower end of the intermediate member, the rods having at each end a protuberance (bulging) for activating the end stop switch in the end position of the rod. This ensures easy control of the position of the end of the lifting column. Furthermore, the motor unit can naturally be equipped with an encoder, such as an optical encoder or a magnetic encoder, for determining the current length of the lifting column from the reading (registration) of the spindle rotation.

Drawings

Further features of the invention will be described more fully hereinafter with reference to the accompanying drawings, in which:

figure 1 shows a schematic view of a hospital bed,

figure 2 shows the lifting column directly from the side in its fully retracted position,

figure 3 shows the lifting column directly shown from the side in its fully extended position,

figure 4 shows an exploded view of the lifting column,

figure 5 shows an exploded view of the chain unit,

figure 6 shows the chain unit seen from the side,

figure 7 shows a longitudinal section through a chain unit,

figure 8 shows the end piece seen from the side,

figure 9 shows a cross-section along the line a-a in figure 8,

figure 10 shows a cross-section along the line B-B in figure 9,

figure 11 shows a perspective view of a slightly different configuration of the end piece,

fig. 12 shows a cross-section through an intermediate member in a lifting column.

Detailed Description

In figure 1 of the drawings the outline of a hospital bed with an upper frame (not shown) and a lower frame 1 equipped with drive wheels is shown. The upper frame is connected to the lower frame 1 by means of telescopic lifting columns 2, 3, wherein the telescopic lifting columns 2, 3 are provided on each end of the bed, which is located on the longitudinal centre axis of the bed. An adjustable base for carrying a mattress is embedded in the upper frame. The base has a backrest portion 4 which can be rotated about a transverse axis to a raised position by a linear actuator 5, such as model LA31 from Linak a/S, denmark. Furthermore, an articulated legrest section 6 is provided, which legrest section 6 is likewise adjustable by means of a linear actuator 7. Between the two parts 4, 6a fixed intermediate part 8 is arranged. The lifting columns 2, 3 and the two actuators 5, 7 are connected by wires to a control box 9, wherein said control box 9 comprises a power supply and a control unit. To control the bed, some hand controls 10 are connected by wires to the control box 9, while foot controls may be provided on each side, and controls for staff (ACP) may also be provided at the leg ends of the bed.

In fig. 2 and 3 of the drawings, the lifting column is shown directly from the side in the fully retracted and fully extended positions, respectively. As shown, the lifting column comprises: a lower member 11 for mounting on the lower frame 1; an intermediate member 12 telescopically extending from the lower member 11; and outermost members 13, the outermost members 13 protruding the intermediate member 12 in synchronization with the protruding of the intermediate member 12 from the lower member 11. Each member is an extruded aluminium tube having a square cross-section which itself acts to prevent rotation of the lifting column. Between the various members there is provided a slide of plastic which, when selected to have a current gap fitting between the tubes, partly provides low friction and partly balances manufacturing tolerances in the aluminium tubes. As can be seen from the exploded view in fig. 4, the lower member 11 is closed at the base by a plate-shaped bottom plate 14. Extruded screw slots are provided in the aluminium tube so that the base plate 14 can be screwed directly onto the end. On the upper ends of the lower 11 and intermediate 12 members a top frame is fixed, which serves first of all to close the gap between the two members, but which also holds the brick slides in place. A flat plate-shaped top plate 17 is fixed to the top of the outermost side member 13, and the flat plate-shaped top plate 17 is similarly fixed by screwing.

As can be further seen from fig. 4, the lifting column comprises a linear actuator 18, said linear actuator 18 having a low voltage reversible dc motor 19, said dc motor 19 having a transmission 20, said transmission 20 driving a spindle 21. This is constructed as a unit which is fixedly mounted to the bottom surface of the top plate 17 with screws. An end-stop circuit (end-stop circuit) is mounted on the same unit.

Furthermore, the lifting column comprises a chain unit, an exploded view of which is shown in detail in fig. 5 of the drawings, and a view from the side and a longitudinal section through the chain unit, respectively, in fig. 6 and 7 of the drawings. The chain unit comprises a body element 22, said body element 22 having a separate upper end piece 23, said upper end piece 23 having a hollow 24, so that said upper end piece 23 can be placed loosely on the end of the long trunk 22a of the body element 22. The sprocket 25 with the shaft 26 can be inserted into a pocket 27 in the end piece, as the shaft 26 is received in a slot 26a for this purpose. A spindle nut 28 can be inserted into the end piece 23, said spindle nut 28 having a collar 29, said collar 29 having a first part of a splined connection, while on the top of the end piece a well 30 is provided for receiving the spindle nut, as the well 30 has another part of the splined connection, so that the spindle nut 28 is fixed in the end piece 23, so that the spindle nut 28 cannot rotate. A tubular passage 31 for the spindle 21 and for receiving the spindle nut 28 passes axially through the body element 22, so that the spindle nut with the collar 29 rests on an extension of the tubular passage 31. The spindle nut 28 is thus secured in the axial direction between the top of the end piece 23 and the upper edge of the tubular channel 31.

A separate lower end piece 32 having a hollow is provided on the lower end of the body element 22 so that the lower end piece 32 can be loosely placed on the end of the trunk 22a of the body element. The sprocket 33 with the shaft 34 can be inserted into the pockets 35 of the end piece, while the shaft 34 is received in the slot 36 for this purpose. The upper and lower end pieces 23, 32 are identical.

The lower end 37 of the body element 22 is convexly curved. An adjustment element 39 can be inserted through an opening 38 in the side of the lower end piece 32, one side 40 of said adjustment element 39 having a concave curved shape corresponding to the curved shape of the body 22a of the body element. Since the trunk 22a of the body member is supported in the hinge joint (hinge), the torque is not transmitted to the main shaft 21, which may otherwise cause the main shaft to break. The main reason for the torque production is, among other things, that the main shaft and the chain (see below) are moved sideways in relation to each other. The other side of the adjustment element 39 is configured as a wedge surface 41, said wedge surface 41 cooperating with a corresponding wedge surface 42 in the top of the hollow of the lower end piece 22. A projection 43 with a threaded hole 44 is provided on the wedge surface 41 of the adjusting element 39. A screw 46 can be inserted through a hole 45 in the side of the end piece 32 so that the adjustment element 39 can be pulled more or less through the opening 38, thereby adjusting the distance between the two end pieces 23, 32, i.e. between the two sprockets, because the two wedge surfaces 41, 42 slide on each other.

An endless chain (end chain)47 runs over the two chain wheels 25, 33, so that a first chain strand 48 and a second chain strand 49 are present between the two chain wheels, wherein a drive rod 50 with a U-shaped cross section is fastened to the first chain strand 48, so that the hollow of said drive rod is placed on the chain. The drive rod 50 is fixed at its free end to the outermost member 13. For this purpose, the housing is inserted into the end of the drive rod so that it can be fixed to the top plate 17 with screws. On the other chain strand, a drive rod 51 with a U-shaped cross section is likewise fixed, and said drive rod 51 is fixed at its free end to the lower member 11. The adjustment element 39 is also advantageous from an assembly point of view. First, the two end pieces 23, 32 are pushed together around the body element 22, after which the chain 47 is placed over the two sprockets, after which the adjusting element 39 is inserted and adjusted for adjusting the tightening length of the chain.

Since the trunk 22a of the main body element having the lower end portion is supported in the hinge, it can be laterally inclined. To avoid this, the end pieces 23, 32 have on each side a lug 52, said lug 52 engaging with a pair of axial tracks 53, wherein said pair of axial tracks 53 are arranged opposite each other on the inner side of the intermediate member 12.

When the lifting column is activated from its fully retracted position, the spindle 21 screws itself out of the spindle nut 28 and the outermost member 13 will start to be driven out of the intermediate member 12 because the spindle is fixed to the top plate 17 on the outermost member 13 by means of a transmission and a motor. Since the chain 47 with the drive lever 50 is fixed to the outermost member 13, the drive lever 50 will be pulled out upward and thereby move the chain 47. However, because the chain 47 with the other drive rod 51 is fixed to the lower member 11, the body element 22 will be pulled upwards, causing the intermediate member 12 to start being driven out of the lower member 11 in synchronism with the outermost member 13.

With regard to the electric motor, it should be noted that it is of the type known colloquially as an "ABS motor", i.e. a short, compact motor developed for ABS braking in automobiles. Current motors have a length of only 55mm and a length/width ratio of 0.78. At the front end of the motor is fixed a mainly cylindrical housing (console)59, said housing 59 having an annular collar 54, said annular collar 54 having a screw tower (tower) for fixing to the top plate 17 with screws.

The front gear 20 is a worm drive in which a worm wheel is fixed to the end of a main shaft 21 just as a bearing is fixed. A ring magnet having four magnetic poles is provided on one side of the worm wheel. A printed circuit with Hall elements (Hall elements) is inserted in the opening of the base 59, which cooperates with the ring magnet for determining the length of the lifting column in accordance with the number of revolutions of the spindle. On the other side of the worm wheel facing the bearing on the end of the spindle, a cylindrical part is provided on which a breaker spring (break spring) of the type described in EP 0662573B 1 link a/S is arranged, which achieves a self-locking function of the spindle. The worm is configured as an extension of the motor shaft, the free end of the worm being pivotally mounted (journal) in a bearing in the wall of the housing.

Extending from the lower end of the housing is a bowl-shaped flange 55 for the motor. On this flange a pocket 56 is provided for fixing an elongated printed circuit 57, the upper end of said printed circuit 57 reaching into said pocket and being fixed by screws. On the lower end of the printed circuit 57a guide 57a for a strip-shaped bar 58 is fixed, said strip-shaped bar 58 being fixed on the base plate 15 in the intermediate member 12 in such a way that it stands vertically from said guide 57a and is guided in an opening in the guide 57a on said printed circuit board. The printed circuit is equipped with two end stop switches located in the guide 57 a. The end stop switch is activated by a bump at each end of the ribbon bar 58 for interrupting the motor at the outermost position of the lifter bar.

The stand 53 is equipped with a bottom having a hole for the spindle 21. The position of the turbine and thus the spindle is determined by a housing located between the bottom of the housing and the housing on the side of the worm wheel. Thereby, the mutual position of the worm wheel and the worm is also determined.

As appears, the lifting rod is structurally simple and consists of only a few parts, and it is also easy to assemble. In particular, the lifting columns exhibit a slim design.

Claims (15)

1. Lifting column for treatment tables, hospitals and nursing beds, with a housing consisting of three telescopic members (11, 12, 13), wherein a drive unit is located in the hollow of the housing, the drive unit comprising two chain wheels (25, 33) on which a chain (47) runs, the chain having a first and a second chain section (48, 49) between the two chain wheels (25, 33), the drive unit further comprising a linear actuator (18) with an electric motor (19), which drives a spindle (21) through a transmission system (20), the spindle (21) having a spindle nut (28) such that the telescopic members (11, 12, 13) extend out of or retract into each other depending on the direction of rotation of the electric motor, characterized in that the three telescopic members of the housing are configured as telescopic guides, the lifting column comprises a body element (22) with the chain (47) and the chain wheels (25, 33), each of the first and second chain strand (48, 49) being provided with a drive rod (50, 51) connected thereto, the spindle (21) being arranged in a cross section of the body element (22), and the spindle nut (28) being located in the body element (22), the spindle nut (28) being fixed against rotation for longitudinal movement of the body element (22) and the chain wheels (25, 33).

2. Lifting column according to claim 1, characterized in that the body element (22) has at least one separate end piece (23, 32) on which one of the sprockets (25, 33) is mounted.

3. Lifting column according to claim 2, characterized in that the body element (22) has a separate end piece (23, 32) on each end, on which end pieces the sprockets (25, 33) are mounted.

4. Lifting column according to claim 2 or 3, characterized in that an adjusting element (39) is provided between an end piece (23, 32) and the body element (22), which adjusting element (39) is used to adjust the distance between the two sprockets (25, 33) in order to tension the chain (47).

5. Lifting column according to claim 4, characterized in that the adjusting element (39) is a wedge-shaped element.

6. Lifting column according to claim 2 or 3, characterized in that the spindle nut is a separate spindle nut (28) embedded on one of the end pieces (23, 32).

7. Lifting column according to claim 2 or 3, characterized in that one of the end pieces (23, 32) is connected to the body element (22) on a tilting axis such that they can be tilted with respect to each other.

8. Lifting column according to claim 7, characterized in that the body element (22) with opposite ends rests on the inner side of the intermediate telescopic member (12).

9. Lifting column according to claim 8, characterized in that the body element (22) with the recess is guided on a longitudinal groove of the telescoping member (12) in the middle.

10. Lifting column according to claim 8, characterized in that the body element (22) with two projections located opposite each other is guided in a pair of longitudinal slits in the intermediate telescopic member (12).

11. Lifting column according to claim 1, characterized in that the electric motor (19) has a length/width ratio of less than 1.

12. Lifting column according to claim 11, characterized in that the front of the electric motor (19) is equipped with a stand for the transmission and bearings of the main shaft (21).

13. Lifting column according to claim 1, characterized in that the drive unit is a worm drive, wherein a worm wheel is mounted on the end of the main shaft and a worm is configured as an extension of the shaft of the electric motor.

14. Lifting column according to claim 12, characterized in that the machine base has a holder in the form of a pocket in which an elongated printed circuit with at least one end stop switch can be fixed.

15. Lifting column according to claim 14, characterized in that a guide is provided on the free end of the elongated printed circuit for a rod standing vertically from the lower end of the middle telescopic member (12), which rod standing vertically from the lower end of the middle telescopic member (12) has a bulge at each end for activating the end stop switch in the end position of the lifting column.