EP1725204A1

EP1725204A1 - A hoist

Info

Publication number: EP1725204A1
Application number: EP05708441A
Authority: EP
Inventors: James Davison; Thomas May
Original assignee: CHILTERN INVADEX Ltd
Current assignee: CHILTERN INVADEX Ltd
Priority date: 2004-03-03
Filing date: 2005-02-23
Publication date: 2006-11-29
Also published as: WO2005084602A1; GB0404803D0

Abstract

A hoist for lifting a patient, the hoist having a housing with a winding mechanism (30) therein arranged to receive a first end of an elongate flexible tensile member (70) and to wind up that member from that end, wherein the hoist includes a magnetic member (92) positioned adjacent and fixed relative to the member and arranged to emit a signal, and a magnetic sensor (90) positioned adjacent the housing (20) and operable to sense a signal emitted by the magnetic member when the magnetic member is adjacent the magnetic sensor, the hoist being operable to cease winding the member in response to the magnetic sensor sensing that the magnetic member is adjacent thereto.

Description

A HOIST

This invention relates to a hoist for lifting a patient.

Motorised hoists are sometimes used for lifting patients who are unable to raise themselves due to old age, injury or some other cause of infirmity. An example of such a hoist has a housing with a winding mechanism mounted therein and arranged to wind up a length of tape around a spool of the mechanism when a motor associated with the winding mechanism is operated by an operator. The hoist is suspended from the tape by attaching its free end, which is that end remote from the hoist, from the ceiling or from structure attached to the ceiling. The housing of the hoist is provided with patient supporting apparatus such as fixed arms projecting therefrom and arranged to bear the weight of a patient.

It is an object of this invention to provide an improved hoist.

According to one aspect of this invention, there is provided a hoist for lifting a patient, the hoist having a housing with a winding mechanism therein arranged to receive a first end of an elongate flexible tensile member and to wind up that member from that end, wherein the hoist includes emitting means positioned adjacent and fixed relative to the member and arranged to emit a signal, and sensing means positioned adjacent the housing and operable to sense the signal emitted by the emitting means when the emitting means is adjacent the sensing means, the hoist being operable to cease winding the member in response to the sensing means sensing that the emitting means is adjacent thereto.

By ceasing winding of the hoist in this way, it is possible to automatically prevent over-winding of the hoist, where such over-winding may cause damage to components of the hoist or cause a patient to be brought dangerously close to the winding mechanism. A hoist that relies on the emission and sensing of a signal, such as a magnetic or electromagnetic signal, rather than on a mechanical switch being triggered, tends to operate more reliably and repeatedly.

The winding mechanism may include a rotatable shaft member to which the first end of the elongate member can be releasably anchored.

According to another aspect of this invention, there is provided a hoist for lifting a patient, the hoist having a housing with a winding mechanism therein arranged to receive a first end of an elongate flexible tensile member and to wind up that member from that end, wherein the winding mechanism includes a rotatable shaft member to which that end can be releasably anchored. A shaft, being of smaller external diameter than a spool or mandrel fitted onto that shaft, can more compactly receive a length of the elongate member wound thereon. Thus, the size of the housing need not be as large as would be necessary were a spool or mandrel used and the elongate flexible member wound thereon.

The hoist of the other aspect may further include emitting means positioned on and fixed relative to the member and arranged to emit a signal, and sensing means positioned adjacent the housing and operable to sense the signal emitted by the emitting means when the emitting means is adjacent the sensing means, the hoist being operable to cease winding the member in response to the sensing means sensing that the emitting means is adjacent thereto.

The emitting means may be arranged to emit a magnetic and/or an electromagnetic signal. The emitting means may be a magnet, such as a permanent magnet. The emitting means may be secured to the elongate member by, for example, an adhesive or by placing the emitting means in a pocket at least partly defined by material of the elongate member. The emitting means may be sewn into a pocket at least partly defined by material of the elongate member. The elongate may be a web of material and preferably is a web of woven material such as, for example, polyester or polypropylene. Preferably the emitting means is positioned adjacent the other end of the elongate member and may be positioned on that other end.

The sensing means may include means for sensing a magnetic field. The sensing means may be a magnetic proximity switch, such as a reed switch. Preferably, the sensing means is positioned on the housing, and may be positioned adjacent to an aperture in the housing through which the elongate member passes.

The shaft may include an aperture therethrough and the elongate member may be anchored to the shaft such that it passes through the aperture. The first end of the elongate member may be arranged to prevent it from passing through the aperture. The first end of the elongate member may have fixed thereto structure that is dimensioned so as not to be able to fit through the aperture. The first end of the elongate member may pass around pin structure that is dimensioned so as not to be able to fit through the aperture. The first end of the member may pass around the pin structure in a loop. The loop may be formed by the first end of member being fixed to material of the member adjacent the first end. The aperture may be arranged such that the pin structure, with the first end of the elongate member therearound, can pass at least partly into the aperture. This may be by one opening of the aperture being larger than the other opening thereof. The aperture may be arranged such that the pin structure is located in the aperture when the flexible member is under tension. The location may include axial location with respect to the axis of the pin, which may also be axial location with respect to the axis of the shaft. The location may include radial location with respect to the shaft. One or both openings of the aperture may be substantially rectangular, one being of greater length and/or width than the other. The larger rectangle may be sized to accept therethrough the looped end of the flexible member with the pin therethrough.

The hoist may include arms for bearing the weight of the patient. The arms may have patient-supporting slings suspended therefrom. The arms may be pivotable relative to the housing between a projecting position in which they project from the housing for bearing the weight of the patient and a stored position in which they lie adjacent the housing.

A specific hoist in which the invention is now embodied is described by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of the hoist from above; Figure 2 is a perspective view of the hoist from below;

Figure 3 is an end elevation view of the hoist;

Figure 4 is a sectional view of a shaft of the hoist; and

Figure 5 is a perspective view of the shaft with tape therethrough.

With reference to Figure 1, the hoist 10 includes a mild steel, box section, housing 20. The housing 20 is arranged such that it has two open and laterally projecting ends 22. All the other faces of the housing 20 are closed. The underside face of the housing 20 has a motor drive assembly 30 fitted thereto. The motor drive assembly 30 includes an electric motor 32 coupled to a reduction worm-gear assembly 34. This is also shown on Figure 2. Batteries are provided in banks 25 running along the outside of the housing 20. An output shaft (not shown) from the centre of the output gear of the worm gear assembly 34 is rotatably mounted in the housing 20 so as to extend from the worm gear assembly 34, through the underside face of the housing 20 and up through the interior of the housing 20. The portion of the output shaft that passes through the interior of the housing 20 has another worm gear (not shown) formed therearound. This worm gear is for driving a winding mechanism 40 of the hoist 10, that winding mechanism 40 being mounted within the housing and arranged as follows.

With reference to Figure 3, the winding mechanism 40 is comprised of two main components. The first of these components is a shaft 50 that is rotatably and transversely mounted in the housing 20. The shaft 50 is fashioned from mild steel and has a larger diameter portion 52 and a smaller diameter portion 54, the two portions 52,54 being axially juxtaposed. The second main component of the winding mechanism 40 is a gear wheel 60. The gear wheel 60 is fixedly mounted on the larger diameter portion of the shaft 50. This mounting is by way of a securing pin (not shown) being placed through the gear wheel 60 and through an aperture in the shaft 50, the aperture being shown at 53 in Figure 4 only.

With reference to Figure 3, whereas the larger diameter portion 52 of the shaft is for receiving the gear wheel 60, the smaller diameter portion 54 of the shaft 50 is for receiving supporting fabric tape 70 by which the hoist 10 is suspended. In order to receive the tape 70, the smaller diameter portion 54 of the shaft 50 has an aperture 56 formed radially therethrough. As can be seen from Figures 4 and 5, the aperture 54 is shaped to allow the tape 70, which is generally flat and wide, to pass radially therethrough. Thus, the aperture 56 has a generally rectangular cross section that extends sideways, in the direction of the axis of the shaft 50. However, and as can be seen in Figure 4, the aperture 56 is not of constant cross section. Instead, a shoulder 58 is provided half way through the aperture 56 such that one entrance 56a to the aperture 56 is of greater width and height than the other entrance 56b. With reference to Figure 5, an end 72 of the tape 70 that is for securing to the shaft 50 is folded over and attached to material of the tape 70 adjacent that end 72 to form a loop. It is envisaged that the attachment of the end 72 of the tape 70 is by sewing. The looped end 72 of the tape extends through the aperture 56 in the shaft 50 from the smaller entrance 56b thereof to emerge from the larger entrance 56a. A securing pin 80 is positioned in the looped end 72 of the tape so that ends of the pin 80 project slightly to each side of the looped end 72. In Figure 5, for clarity of illustration, the tape 70 is show to be slack and not to pull on the shaft 50. However, as the hoist 10 is suspended by the tape 70, the tape 70 is under tension and pulls on the shaft 50. In so doing, the tape 70 tries to pull its looped end 72, with the pin 80 therethrough, through the aperture 56 from the larger entrance 56a towards the smaller entrance 56b. However, the pin 80 and the aperture 56 of the shaft 50 are dimensioned such that the pin is too large to pass through the smaller entrance 56b. Instead, the pin 90 abuts on the shoulder 58 of the aperture 56. Thus, the looped end 72 of the tape 70 is anchored to the shaft 50 by the pin 80 when the tape 70 is under tension. As shown in Figures 1 and 3, the remainder of the tape 70 extends from the shaft 50, over one or more transversely-extending guide bars 24 to emerge from the housing 20 of the hoist through a slot 26 formed in upper face of the housing 20. The slot 26 is shown in Figure 1, with the tape 70 emerging therefrom.

With continued reference to Figure 1, a magnetic proximity sensor in the form of a reed switch 90 is positioned on the upper surface of the housing 20, next to the slot 26 formed therein. The reed switch 90 is electrically connected to circuitry that is operable to suspend operation of the electric motor 32 when the reed switch 90 is operated by the effect of an adjacent magnetic field. The end portion 74 of the tape 70 that is remote from the housing 20 of the hoist 10 is attached to a ceiling-mounted trolley (not shown) arranged to run in tracks across a ceiling. This remote end 74 of the tape 70 has a permanent magnet 92 attached to it. The permanent magnet 92 is sewn into a pocket 94 created by looping over the remote end portion 74 of the tape 70.

In use, a patient (not shown) to be lifted by the hoist 10 is suspended from the housing 20 by any means suitable for such a purpose. Although not shown, it is envisaged, for example, that housing 20 be provided with a pair of projecting arms from which slings depend that are arranged to be passed around the body of the patient for taking that patient's weight. The hoist 10 is then operated by supplying electrical power to the electric motor 32 from the banks of batteries 25. The motor 32 drives the reduction worm gear assembly 34, which in turn drives the winding mechanism 40 by rotating the gear wheel 60 thereof. The gear wheel 60, being mounted about the shaft 50, then causes that shaft 50 to rotate. Rotation of the shaft 50 winds up the tape 70 from the looped end 72 and causes the housing 20 to rise up the suspended tape 70.

This can continue until the magnet 92 fixed at the remote end 74 of the tape 70 relatively approaches the reed switch 90 on the housing 20. When the magnet 92 is near the reed switch 90, that switch 90 is operated by the magnetic field associated with the magnet 92, and operation of the electric motor 32 is thereby suspended. Thus, the housing 20 of the hoist 10 proceeds no further up the tape 70 towards the remote end 74 thereof.

Claims

CLAIMS:

1. A hoist for lifting a patient, the hoist having a housing with a winding mechanism therein arranged to receive a first end of an elongate flexible tensile member and to wind up that member from that end, wherein the hoist includes emitting means positioned adjacent and fixed relative to the member and arranged to emit a signal, and sensing means positioned adjacent the housing and operable to sense the signal emitted by the emitting means when the emitting means is adjacent the sensing means, the hoist being operable to cease winding the member in response to the sensing means sensing that the emitting means is adjacent thereto.

2. A hoist according to claim 1 in which the winding mechanism includes a rotatable shaft member to which the first end of the elongate member can be releasably anchored.

3. A hoist according to claim 1 or claim 2 in which the emitting means is arranged to emit a magnetic and/or an electromagnetic signal.

4. A hoist according to any preceding claim in which the emitting means is a magnet, such as a permanent magnet.

5. A hoist according to any preceding claim in which the emitting means is secured to the elongate member by an adhesive.

6. A hoist according to any preceding claim in which the emitting means is secured to the elongate member by placing the emitting means in a pocket at least partly defined by material of the elongate member.

7. A hoist according to claim 6 in which the emitting means is sewn into the pocket.

8. A hoist according to any preceding claim in which the elongate member comprises a web of material and preferably is a web of woven material such as, for example, polyester or polypropylene.

9. A hoist according to any preceding claim in which the emitting means is positioned adjacent an end of the elongate member opposite said first end.

10. A hoist according to any preceding claim in which the sensing means includes means for sensing a magnetic field.

11. A hoist according to claim 10 in which the sensing means comprises a magnetic proximity switch, such as a reed switch.

12. A hoist according to any preceding claim in which the sensing means is positioned adjacent to an aperture in the housing through which the elongate member passes.

13. A hoist according to any preceding claim when dependent on claim 2 in which the shaft includes an aperture therethrough and the elongate member is anchored to the shaft such that it passes through the aperture.

14. A hoist according to claim 13 in which the first end of the elongate member is arranged to prevent it from passing through the aperture.

15. A hoist according to claim 13 or claim 14 in which the first end of the elongate member has fixed thereto structure that is dimensioned so as not to be able to fit through the aperture.

16. A hoist according to claim 15 in which the first end of the elongate member passes around a pin structure that is dimensioned so as not to be able to fit through the aperture.

17. A hoist according to claim 16 in which the first end of the member passes around the pin structure in a loop.

18. A hoist according to claim 17 in which the aperture is arranged such that the pin structure, with the first end of the elongate member therearound, can pass at least partly into the aperture.

19. A hoist according to claim 18 in which one opening of the aperture is larger than the other opening thereof.

20. A hoist according to claim 19 in which the aperture is arranged such that the pin structure is located in the aperture when the flexible member is under tension.

21. A hoist according to any preceding claim in which the hoist includes arms for bearing the weight of the patient.

22. A hoist according to claim 21 in which the arms have patient-supporting slings suspended therefrom.

23. A hoist according to claim 21 or claim 22 in which the arms are pivotable relative to the housing between a projecting position in which they project from the housing for bearing the weight of the patient and a stored position in which they lie adjacent the housing.

24. A hoist for lifting a patient, the hoist having a housing with a winding mechanism therein arranged to receive a first end of an elongate flexible tensile member and to wind up that member from that end, wherein the winding mechanism includes a rotatable shaft member to which that end can be releasably anchored.

25. A hoist according to claim 24 further including emitting means positioned on and fixed relative to the member and arranged to emit a signal, and sensing means positioned adjacent the housing and operable to sense the signal emitted by the emitting means when the emitting means is adjacent the sensing means, the hoist being operable to cease winding the member in response to the sensing means sensing that the emitting means is adjacent thereto.

26. A hoist for lifting a patient, the hoist having a housing with a winding mechanism therein arranged to receive a first end of an elongate flexible tensile member and to wind up that member from that end, wherein the hoist includes a magnetic member positioned adjacent and fixed relative to the member and arranged to emit a signal, and a magnetic sensor positioned adjacent the housing and operable to sense a signal emitted by the magnetic member when the magnetic member is adjacent the magnetic sensor, the hoist being operable to cease winding the member in response to the magnetic sensor sensing that the magnetic member is adjacent thereto.