Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
  • A61G7/00—Beds specially adapted for nursing; Devices for lifting patients or disabled persons
  • A61G7/002—Beds specially adapted for nursing; Devices for lifting patients or disabled persons having adjustable mattress frame
  • A61G7/018—Control or drive mechanisms
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
  • A61G7/00—Beds specially adapted for nursing; Devices for lifting patients or disabled persons
  • A61G7/002—Beds specially adapted for nursing; Devices for lifting patients or disabled persons having adjustable mattress frame
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
  • H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
  • H02H7/0851—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load for motors actuating a movable member between two end positions, e.g. detecting an end position or obstruction by overload signal

Definitions

• the present invention relates to a device in a drive arrangement for adjustable articles of furniture, said arrangement comprising at least an electrical drive unit intended for mounting in the article of furniture to adjust a movable part thereof, a control box containing a mains-based power supply as well as control electronics, a mains cable for connecting the control box to a plug, a wire for each drive unit for connecting it to the control box, and a manual control and/or operating panel for activating the drive unit(s).
• WO 93/11593 to Okin relates to an off-mains switching device for such a drive arrangement, but this does not protect completely against the above- mentioned conditions.
• a not very great, but nevertheless real risk is in- volved by the mains voltage on the manual control if, the mains cable is damaged, since, in practice, this contains conductors for the mains voltage as well conductors for the cut-off relay. If a separate cable is run to the plug and a separate wire is run to the disconnection relay, the relay may be activated even though the cable has been torn completely apart, since the relay is activated by an auxiliary voltage source. Further, the mains disconnection device does not take any overloading of the drive arrangement into account.
• the invention focuses on the above-mentioned problems in order to provide a solution intended to diminish and preferably entirely avoid these.
• the invention provides a solution which is characterised in that the device comprises a circuit for monitoring the power consumption, and a relay connected to the device and arranged in the connection to the mains to interrupt the mains voltage if a power consumption outside a predetermined permissible level is detected. It is ensured hereby with almost absolute certainty that the current to the drive arrangement is interrupted if damage or a defect occurs in the drive arrangement that might cause a fire or result in personal injury because of an electric shock.
• the device may be incorporated in the plug on the mains cable, or be constructed as a separate unit to be arranged between a plug and the mains cable, whereby the device may be made universally useful and be used in connection with existing drive arrangements.
• the level within which the power is to be kept is divided into three levels, which may be called a start phase, an operating phase and a standby phase.
• a great current is allowed quite briefly to obviate drop-out because of an instantaneous, great draw of power at the start of the drive arrangement.
• the standby phase a quite small draw of power is required and allowed to cover no-load losses in the system, which are essentially constituted by no-load losses in the transformer. If such a small draw of power is not observed, this is indicative of an unauthorised interruption, e.g. a mains cable rupture, a blown fuse, etc.
• the operating phase may be graduated according to the current loading conditions of the drive arrangement, e.g.
• a great draw of power may be allowed for a short period corresponding to a severe load of the drive arrangement, and a smaller draw of power for an extended period of time corresponding to a normal load.
• Heat is generated in the drive arrangement during operation, and the generation of heat is particularly great at extreme loads.
• the drive arrangement cools during standstill.
• the periods of a high and a smaller draw of power are expediently determined as an integration over a certain period of time in view of the thermal conditions in the drive arrangement.
• Fig. 1 shows a hospital bed
• fig. 2 shows a schematic diagram of the drive arrangement for adjustment of the bed
• fig. 3 shows a curve of energy consumption
• fig. 4 shows a block diagram of the device according to the invention.
• the bed shown in fig. 1 is a typical hospital bed, but the drive arrangement in a sickbed and a domestic bed is basically the same, except that a domestic bed is usually not adjustable in the height.
• the bed comprises a frame 1 which accommodates a support for a mat- tress, said support consisting of a pivotable back section 2, a fixed central section 3 and a pivotable leg section 4 which is articulated.
• the back and leg sections 2, 4 may be adjusted by means of their respective linear actuators 5, 6.
• the support as a whole is adjustable in the height, just as it may be tilted about its transverse axis with two linear actuators 7, 8.
• control box 9 (not shown in fig. 1) which accommodates a 24V power supply based on a transformer, and which also contains control electronics and a battery pack.
• the control box is connected by a cable 10 to the mains voltage.
• Each actuator 5-8 is also connected to the control box by a multi-membered wire, in which supply voltage as well as control signals are conveyed.
• a manual control 11 is pro- vided for the control of the actuators and is connected to the control box by a wire.
• the bed may be equipped with an additional control panel 12, which may exclusively be operated by authorised hospital staff.
• the plug 13 of the mains cable 10 is provided with a circuit which monitors the power consumption of the control box.
• the monitoring circuit is connected to a switch relay likewise disposed in the plug 13 for interruption of the mains voltage if a power consumption outside a predetermined level is detected.
• the last stage on the curve is a small permanent consumption, which, with a certain small overmargin, covers a standby consumption, which is essentially constituted by the no-load consumption of the transformer. If this small permanent consumption is not detected, the relay interrupts the mains connection, since this is indicative of a defect in the connection to the primary side of the transformer.
• 14A, 14B indicates the switch relay in the mains connection.
• the relay is coupled so that in a position of rest it interrupts the mains voltage, while in an excited state it connects the mains voltage, which protects against defects.
• the necessary voltage is supplied by an internal power supply 15 based on the mains voltage.
• the relay is activated by a single FET transistor 16.
• a first measuring circuit 19A for measuring the power consumption is inserted into one conductor in the mains connection.
• the measuring circuit is connected to the FET 16 via a recording unit 17, which is in turn connected to a starter logic 18. If no power in the mains connection is detected, the relay is deactivated and the mains connection is interrupted.
• This measuring circuit 19A is based on diodes, since the power at idle load is very small.
• a second measuring circuit 19B is likewise connected to the FET via the starter logic 18, but this is made via four integrators 20-23 which control the relay in accordance with what has been described previously, e.g. a power equivalent to a consumption of 350W for more than 47 ms will turn off the FET via the starter logic and thereby deactivate the relay, and the mains connection will be interrupted.
• the measuring circuit 19 is based on a measurement resistance, since the power consumption in the situations concerned is considerably greater than at standby.
• the invention thus provides a simple and reliable protection against damage resulting from electrical defects in the drive arrangement and moreover allows for blockages of it.

Landscapes

• Health & Medical Sciences (AREA)
• Nursing (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Invalid Beds And Related Equipment (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=26069009

Family Applications (1)

Country Status (2)

Cited By (1)

Families Citing this family (4)

Family Cites Families (4)

• 2002
  • 2002-04-24 WO PCT/DK2002/000265 patent/WO2002091539A1/en not_active Application Discontinuation
  • 2002-04-24 EP EP02735088A patent/EP1389355A1/de not_active Withdrawn

Non-Patent Citations (1)

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