GB2214732A

GB2214732A - Backup power supply for invalid hoist

Info

Publication number: GB2214732A
Application number: GB8801174A
Authority: GB
Inventors: Mark Rawlinson Bailey
Original assignee: CHILTERN MEDICAL DEVELOPMENTS
Current assignee: CHILTERN MEDICAL DEVELOPMENTS
Priority date: 1988-01-20
Filing date: 1988-01-20
Publication date: 1989-09-06
Also published as: GB8801174D0

Abstract

An invalid hoist can be raised and lowered by an electric motor 10, and a backup power supply 20 may be selectively connected to the motor 10 to enable at least the lowering of the hoist if the normal supply 11, 12 fails. The backup supply may be an alkaline battery having a connector 21, or a constantly charged rechargeable battery may be permanently fitted inside a case of the hoist. <IMAGE>

Description

Improvements in or Relating to Hoists for Invalids.

l This invention relates to hoists for use by invalid or disabled persons. In particular the invention relates to driving means for providing motive power to such a hoist. Hoists for the disabled are usually suspended from a rail which is itself attached securely to a ceiling or similar structure. The hoist can be operated by a person sitting in it so that it can be raised and then moved along a path permitted by the rail. Motive power for the hoist is usually provided from an electric motor. A problem with such arrangements is that the hoist can be left suspended in the air if there is a power failure, or if there is a problem with the power supply. The present invention is designed to overcome or alleviate this problem.

According to the present invention there is provided a drive means for providing motive power to an electrically driven hoist for disabled persons comprising a motive power unit, a source of primary electrical energy for energising the power unit to cause raising or lowering of the hoist, and a secondary source of electrical energy selectively connectable to the motive power unit in the event of a failure of the primary source to enable at least the lowering of the hoist.

The motive power unit may be a d.c. motor. The primary source of electrical energy may be a d.c.

voltage derived by transforming and rectifying the a.c. mains supply. The secondary source of electrical energy may be a long life alkaline battery.

Alternatively the secondary source of electrical energy may be a rechargeable battery.

The secondary source of electrical energy, which can take the form of 9 volt dry cell battery, provide the user of a hoist with an emergency lowering facility in the event of a problem with the primary source.

The invention will be described now by way of example only, with particular reference to the accompanying drawing, which is a circuit diagram illustrating an electrical drive circuit for operating a hoist for disabled persons.

The drive circuit shown in the drawing is for operating an electric hoist which is manufactured by Chiltern Medical Developments Ltd. under the name WISPA. A detailed description of the hoist will not be provided since they are not necessary for an understanding of the invention. Briefly such hoists are suspended from a rail mounted typically on a ceiling support. The hoist can be raised and lowered relative to the rail by means of an electric motor. A sling for a disabled person or invalid is attached to the hoist. When in its raised position the hoist can be driven along the rail to allow the disabled person to move from one position to another whilst sitting in the sling. Referring to Figure 1, the hoist can be raised and lowered by operation of an electric motor which is shown at 10 in the drawing. The hoist is used to raise and lower a sling in which a disabled person can sit.

The motor shown at 10 in the drawing is a 24 volt d.c.

motor which is energised from a 24 volt d.c. supply having terminals 11 and 12. The motor can be driven in one of two directions to either raise or lower the hoist and the direction of drive is determined by the position of contacts 14, 15. These contacts can be reversed by operation of a switch disclosed at a suitable location for actuation by the user of the hoist. The 24 volt d.c. supply can be derived from the a.c. mains by means of a transformer and a rectifier. It will be seen that the circuit includes a light emitting diode 16 which is simply an indicator lamp to indicate that the device is operational.

The present drive circuit is provided with an auxiliary or secondary power source shown at 20. This is a 9 volt dry cell battery which is connected via an external plug and socket shown at 21 to the normal 24 volt d.c. supply for the motor 10. If the usual 24 volt d.c. supply fail, when the hoist is in a raised position it is possible to carry out emergency lowering of the hoist using the secondary power supply 20. When this battery is plugged in and control switch is pressed the motor 10 will turn slowly enabling the disabled person or patient to be lowered safely to ground level. To save battery power when operating in this emergency lowering mode the light emitting diode 16 can be switched off automatically in that mode. It is anticipated that up to thirty operations can be made using one long life alkaline battery.

It should be noted that in normal operation of the motor 10 the armature connections are shorted out (close), which gives resistance to the motor armature turning thereby forming an electrical break. As with all d.c. permanent magnet motors, when they are back driven it produces a voltage output. The greater the load across the output the greater the effort which is required to turn the armature.

As shown in the Figure the auxiliary or secondary power supply is a dry cell battery. An alternative form of supply to enable emergency lowering could be provided by a constantly charged rechargeable battery permanently fitted inside the hoist case. In this situation all that the patient requires to do is to press down a button on the control box of the hoist.

Claims

CLAIMS:

1. A drive means for providing motive power to an electrically driven hoist for disabled persons comprising a motive power unit, a source of primary electrical energy for energising the power unit to cause raising or lowering of the hoist, and a secondary source of electrical energy selectively connectable to the motive power unit in the event of a failure of the primary source to enable at least the lowering of the hoist.

2. A drive means as claimed in claim 1, wherein the motive power unit is a d.c. motor.

3. A drive means according to claim 1 or claim 2, wherein the primary source of electrical energy is a d.c. voltage derived by transforming and rectifying the a.c. mains supply.

4. A drive means according to any preceding claim, wherein the secondary source of electrical energy is a long life alkaline battery.

5. A drive means according to any one of claims 1 to 3, wherein the secondary source of electrical energy is a rechargeable battery.

6. A drive means according to any preceding claim, wherein the secondary source of energy its permanently mounted on the hoist.

7. A drive means substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

8. An electrically driven hoist for a disabled person incorporating a drive means according to any preceding claim.