DEVICE FOR INTERRUPTING LOWERING MOVEMENTS OF MOTOR-DRIVEN HOISTING GEARS AT PATIENT-LIFTING UNITS

Abstract: The present invention relates to a device for interrupting lowering movements of motor-driven hoisting gears at patient-lifting units, whereby the hoisting gear (5) comprises an anchoring member (7) through which the hoisting gear is fixed onto a frame (3) or similar, and a displacement member (9) which is connected to the anchoring member and raisable and lowerable in relation thereto by means of a motor (17), whereby sitting and/or lying means (6) for patients is mounted on the displacement member through a bracket (21). In order to eliminate the risk of patients being caught between the sitting and/or lying means and an obstacle, e.g. a bed, and prevent the patient-lifting unit from being lifted from the floor and/or tipping because the sitting and/or lying means proceeds downwards after bumping into the ob­ stacle, e.g. the bed, the bracket (21) is journalled on the displacement member (9) through a device (30, 32) permit­ ting relative movements between said bracket and displace­ ment member such that the displacement member, during lowering thereof by means of the motor (17) may proceed some distance further downwards after the sitting and/or lying means (6) has run into an obstacle (2), whereby sensing and control means (33) is provided to sense the change of position occuring between the displacement member and bracket when the displacement member proceeds further downwards while the bracket is prevented therefrom by the sitting and/or lying means bumping into said obstacle and whereby the sensing and control means is provided to control the motor to stop in dependence of said change of position and thereby interrupt continued downward move­ ment of the displacement member.

Description: DEVICE FOR INTERRUPTING LOWERING MOVEMENTS OF MOTOR-DRIVEN HOISTING GEARS AT PATIENT-LIFTING UNITS. The present invention relates to a device for interrupting lowering movements of motor-driven hoisting gears at patient -lifting units, whereby the hoisting gear comprises an anchoring member through which the hoisting gear is fixed onto a frame or similar, and a displacement member which is connected to the anchoring member and raisable and lowerable in relation thereto by means of a motor, whereby sitting and/or lying means for patients is mounted on the displacement member through a bracket. At patient-lifting units of the above type, there is a risk that the lowering movement of the sitting and/or lying means because of lack of attention or for other reasons are not interrupted before said sitting and/or lying means runs into an obstacle, e.g. a bed. This may cause that the patient or someone else is caught between the sitting and/or lying means and the bed or the patient-lifting unit may be more orlesslifted from the ground or even tip with a patient sitting or lying thereon. The object of the present invention is to eliminate this problem by means of a simple and reliable device. This is arrived at by providing the device with the characterizing features of claim 1. The device according to the invention provides an automatic lowering stop by sensing the change of position occuring when the sitting and/or lying means runs into an obstacle while the displacement member of the hoisting gear proceeds further downwards. Thus, the lowering movement is automatically interrupted before any serious risks of squeezing or of instability and tipping occur. The invention will be further described below with reference to the accompanying drawings, in which fig. 1 is a side view of a patient-transporting waggon at which a patient-lifting unit has a device according to the invention; fig. 2 is a side view of the patient-transporting waggon standing beside a bed, whereby a sitting and lying means is shown with solid lines before it is lowered to the bed and with dashed and dotted lines after lowering to the bed; fig. 3 is a side view of the hoisting gear, whereby members forming part thereof are shown in their drawn-apart positions because of the sitting and/or lying means engaging the bed; and fig. 4 finally, is a switch diagram forming part of the device of the invention. The patient-transporting waggon 1 illustrated in the drawings is adapted for transporting patients between various locations, e.g. to or from a bed 2. The patient-transporting waggon 1 has a transportable frame 3 with four wheels 4. A hoisting gear 5 (a so called hoisting column) is mounted on the frame 3 and a seat 6 for the patient is provided on top of the hoisting gear. The hoisting gear 5 is adapted to raisethe seat 6 to such a level that it may be located above the bed 2 and lowered thereto for transferring a patient from or to the seat. The hoisting gear 5 comprises an anchoring member 7 which is fixed onto the frame 3 by means of a screw joint 8. The hoisting gear 5 also comprises a displacement member 9 which by cooperation with the anchoring member 7 is movable in vertical direction. In order to carry out this movement, the anchoring member 7 comprises a sleeve 10 with an inner threaded portion 11 and the displacement member 9 comprises a threaded bar 12 projecting downwards into the sleeve. Between the threads of the sleeve 10 and the bar 12 respectively, balls 13 are provided in such a way that the sleeve 10, bar 12 and balls 13 together define a so called ball screw 14. The upper end portion of the threaded bar 12 projects upwardly into a gearbox 15 forming part of the displacement member 9 and is provided with a pinion 16. The gearbox 15 is assembled with an electric motor 17, the driveshaft 18 of which is provided with a pinion 19 meshing with the pinion 16 of the gear box. The pinions 16, 19 are adapted to, during shifting, transfer the driving movement of the motor 17 to the threaded bar 12 for rotation thereof, i.e. to drive the ball screw 14. Since the motor 17 rotates the bar 12 in one direction relative to the sleeve 10, the displacement member 9 is moved upwards, and by rotating the bar in the opposite direction, the displacement member is moved downwards. A downward sleeve 20 mounted on the gearbox 15 surrounds the ball screw 14. A bracket 21 for the seat 6 and the arm and back support 22 of the patient-lifting unit is mounted on the displacement member 9. The bracket 21 consists of a box-like upper portion 21a and a cylindrical sleeve 21b projecting downward therefrom. A yoke 27 (only schematically shown in the drawings) is provided on the cylindrical sleeve 21b for mounting the seat 6 and arm and/or back support 22. The box-like part 21a of the bracket 21 is adapted to provide a hood for the electric motor 17 and a battery box 23 with a battery is mounted thereon, said battery being connected to the motor for driving thereof. The frame 3 is provided with an upwardly directed cylindrical guide sleeve 25 with a laterally-extending guiding arm 26 on top thereof. The sleeve 21b of the bracket 21 surrounds the guide sleeve 25 and provides a lateral passage 28 for the guiding arm 26. While the guiding arm 26 projects into the passage 28, it prevents the sleeve 21b and thus, the bracket 21 from rotating relative to the frame 3 during raising and lowering. For retaining the bracket 21 on the displacement member 9, the gearbox 15 forming part of the displacement member is on top provided with an upwardly directed fork 29 with a shaft journal 30 extending horizontally between two shanks defining the fork. The box-like part 21a of the bracket 21 has a horizontally directed arm 31 with a long-hole 32 for the shaft journal 30. The arm 31 projects in between the shanks of the fork 29 such that the shaft journal 30 extends through the long-hole 32 in the arm, whereby the arm and the bracket 21 with their various parts will hang on the displacement member 9 through the shaft journal. The long-hole 32 is vertically directed and the length thereof about twice the diameter of the shaft journal 30. Normally, the upper edge of the long-hole will engage the shaft journal 30 (see fig. 1), but the long-hole permits the shaft journal to move downwards in the hole until it engages the lower edge of the long-hole (see fig. 3). Thus, the displacement member 9 is movable relative to the bracket 21 or vice versa and changes of position between said members 9, 21 are sensed by sensing and control means 33 forming part of the electric circuit 34 (see fig. 4) of the motor 17 and adapted to disconnect the circuit for automatically interrupting the lowering movement of the hoisting gear 5 when the seat 6 bumps into the bed 2 or any other obstruction. The sensing and control means 33 is mounted on the bracket 21 above the gearbox 15 and it has a protruding contact relay 35. The sensing and control means 33 is located on the bracket 21 relative to the long-hole 32 in the arm 31 such that the contact realy 35 thereof is depressed by the gearbox 15 when the upper edge of the long-hole engages the shaft journal 30, i.e. when the bracket is located in the normal position relative to the displacement member 9 indicated in fig. 1. In this position (solid -line position S in fig. 4) the contact relay 35 closes its portion 36 of the circuit 34 of the motor 17 such that the bracket 21 with associated seat 6 is lowered by pressing the operating unit 37 located on the bracket from neutral position 0 to position N (shown with solid lines in fig. 4) or raised by pressing the operating unit from neutral position 0 to position U (shown with dashed and dotted lines in fig. 4). If however, the seat 6 is lowered so far that it hits the bed 2, the sensing and control means 33 controls the motor 17 to stop automatically. When the seat 6 reaches the bed 2 and is prevented from prodeecing downwards, the motor 17 will drive the displacement memeber 9 a distance further downwards, because the long-hole 32 in the arm 31 will allow it until the shaft journal 30 reaches the lower edge of the hole (see fig. 3). This means that also the gearbox 15 will be lowered relative to the sensing and control means 33 such that spring means (not shown) may press out the contact relay 35 to a position (position B in fig. 4 shown with dashed and dotted lines ) at which it disconnects its portion 36 of the circuit 34 to the motor 17, whereby the motor stops and the lowering movement is automatically interrupted. A further lowering of the displacement member 9 and thus the seat 6, is not possible thereafter. By thereafter moving the operating unit 37 to position U, the portion 38 of the circuit 34 is connected, which means that the motor 17 is operated to rotate for raising the displacement member 9. Elevation of the displacement member 9 causes the shaft journal 30 to move upwards in the long-hole 32 until it engages the upper edge of said hole and brings along the bracket 21 and thereby, the seat 6. Hereby, the contact realy 35 of the sensing and control means 33 is once again depressed by the gearbox 15 to position S shown with solid lines in fig. 4, at which position it conntectsits portion 36 of the circuit 34 such that the displacement member 9 may once again be lowered by moving the operating unit 37 to position N. Means 39 is provided between the displacement member 9 and the bracket 21 and adapted to apply an upwardly directed force to the bracket for reducing the pressure with which the seat 6, because of the weight of the seat and bracket, loads the bed 2 when the seat reaches it during lowering. Hereby, eventual squeezing forces are reduced and automa tic disconnection of the lowering movement of the electric motor 17 occurs quicker even if the seat 6 reaches a relatively resilient or vielding part of the bed 2. The power generating means 39 preferably comprises a compression spring 40 which is located between the gearbox 15 and the arm 31 and this spring, or similar, affects the arm 31 with such an upwardly directed force which equalizes at least the major part, preferably about 90% of the force with which the bracket 21 and the members mounted thereon, because of their weight, load the compression spring 40 in downwards direction. The upwardly directed force of the compression spring 40 however, may not exceed the downward force of the bracket 21 and associated members on said spring, since the spring otherwise will move the bracket upwards to its upper position (see fig. 3) relative to the displacement member 9, whereby the sensing and controlling means 33 disconnects its portion 36 of the circuit 34 and render it impossible to lower the bracket 21 with its seat 6. The device illustrated in the drawings and described above, may vary within the scope of the following claims without departing from the essential function thereof, i.e. to sense, by means of a simple sensing and control device, those changes of position permitted by a simple movement permitting device and in dependence thereon control the motor to automatically inerrupt lowering of the seat when said seat during lowering bumps into an obstacle of any kind, e.g. a bed. As an alternative (not shown), the movement permitting device may be designed in a totally different manner than as shown (e.g. a long-hole may instead be provided in the displacement member and a shaft journal extending therethrough may form a part of the bracket). The sensing and control means may also be designed in quite a different way and located in another position. The hoisting gear of the patient-lifting unit may also vary in its design within certain limits and if a ball screw device is used, said device may be provided with a brake device preventing the seat from being lowered during overload conditions. The bracket for the seat may also vary in its shape and location and the seat may be either simple sitting means or sitting and/or lying means for the patient. The means affecting the bracket in upwards direction may consist of one or more springs or other types of power generating means. Eventually, such means may be adjustable with regard to the rating of the force generated thereby. The power generating means may also be located in another position than indicated above and in the drawings. It is preferable but not absolutely necessary to design the bracket with a box-like part and provide various devices such as the relative movements permitting device and/or the sensing and control means and/or the motor inside said box-like part in a protective manner. Finally, it may be noticed that the patient-lifting unit with the device according to the invention may be used in other applications than for patient-transporting waggons of the described and illustrated type.

Claims: Claims 1. Device for interrupting lowering movements of motor-driven hoisting gears at patient-lifting units, whereby the hois ting gear (5) comprises an anchoring member (7) through which the hoisting gear is fixed onto a frame (3) or simi lar, and a displacement member (9) which is connected to the anchoring member and raisable and lowerable in rela tion thereto by means of a motor (17), whereby sitting and/or lying means (6) for patients is mounted on the displacement member through a bracket (21), c h a r a c t e r i z e d i n that the bracket (21) is journalled on the displacement member (9) through a device (30, 32) permitting relative movements between said bracket and displacement member such that the displacement member, during lowering thereof by means of the motor (17) may proceed some distance further downwards after the sitting and/or lying means (6) has run into an obstacle (2), whereby sensing and control means (33) is provided to sense the change of position occuring between the displace ment member and bracket when the displacement member proceeds further downwards while the bracket is preven ted therefrom by the sitting and/or lying means bumping into said obstacle and whereby the sensing and control means is provided to control the motor to stop in depen dence of said change of position and thereby interrupt continued downward movement of the displacement member. 2. Device according to claim 1, c h a r a c t e r i z e d b y means (39) affecting the bracket (21) relative to the displacement member (9) with an upwardly directed force in order to reduce the pressure otherwise applied onto the obstacle (2) by the bracket and associated mem bers because of the weight thereof when the sitting and/or lying means (6) during lowering has bumped into the obstacle. 3. Device according to claim 2, c h a r a c t e r i z e d i n that said means (39) for applying an upwards force onto the bracket (21), generates an upwardly directed force which corresponds to the major part, preferably about 90%,of a downward force applied onto said means by the bracket and associated members because of their weight. 4. Device according to claim 2 or 3, d h a r a c t e r i z e d- i n that said means (39) for applying an upwards torce onto the bracket (21) is a compression spring (40). 5. Device according to any preceding claim, c h a r a c t e r i z e d i n that the device permitting relative movements between the bracket (21) and displacement mem ber (9) comprises a long-hole (32) provided in one of the movable members (21 or 9) and a shaft journal (30), extending through the long-hole and movable therein in vertical direction, on the other of the movable members (9 or 21). 6. Device according to any preceding claim, c h a r a c t e r i z e d i n that the sensing and control means (33) is mounted on the bracket (21) and provided with a contact realy (35) which is held in a connecting position (S) by the displacement member (9) wherein it connects a lowering portion (36) of an electric circuit (34) to the motor (17) of tne hoisting gear (b) and wnicn is automatically switcned to a position (B) dis connecting the lowering portion (36) or the circuit (34) for interrupting the lowering movement ot the motor when the displacement members is moved further down wards relative to the bracket as the sitting and/or lying means (6) bumps into the obstacle. 7. Device according to any preceding claim1 c h a r a c t e r i z e d i n that the bracket (21) comprises a box-like part (21a) housing the device (30, 32) permitting relative movements between the bracket and the displacement member (9) as well as the sensing and control means (33). 8. Device according to any preceding claim, c h a r a c t e r i z e d i n that the bracket (21) comprises a box-like part (21a) provided on top of the hoisting gear (5) and including the motor (17) for operating said hoisting gear and those parts (15) of the displace ment member (9) cooperating with the sensing and control means (33).

Inventors: SANDELL, ANDERS LENNART, SONESSON, LEIF BERTIL
Applicants: ARJO HOSPITAL EQUIPMENT AB
Application year: 1985
Main classification: A61G7
IPC codes: B66F17, A61G7