GB2357069A

GB2357069A - Unwind motor limit switch

Info

Publication number: GB2357069A
Application number: GB9924349A
Authority: GB
Inventors: William David Steadman
Original assignee: SILVER CROWN ASSOCIATES Ltd
Current assignee: SILVER CROWN ASSOCIATES Ltd
Priority date: 1999-10-15
Filing date: 1999-10-15
Publication date: 2001-06-13
Anticipated expiration: 2019-10-15
Also published as: EP1092409A3; GB2357069B; EP1092409A2; GB9924349D0

Abstract

A limit switch assembly is provided which prevent the fill unwinding and hence potential reverse winding of a band 14 of a bath lift. The assembly 10 comprises an elongate member 18 that rotates as the band is unwound, and an engagement member 20, that may be in the form of a nut, moves transversely along the elongate member. Rotation of the nut is prevented by an abutment member 22, which may be in the form of a pivotable plate which can be moved away from the nut to allow it to be adjusted. The nut operates a microswitch 24, which may be further adjusted so that it stops rotation of the elongate member at a predetermined position. In an alternative embodiment, the nut can be replaced by a profiled engagement member (32, figure 3) which has an adjustable screw (42, figure 3) to operate the microswitch, and the screw may be locked in place by a lock screw (44, figure 3).

Description

2357069 ANTI-UNWIND ASSEMBLY This invention concerns an anti-unwind

assembly, and particularly but not exclusively to such an assembly to prevent full unwinding of a band on a bath lift.

One type of bath lift comprises a band which selectively extends across the bath and can be sat on when taut. The band is then unwound for a housing to lower a person into the bath, and can be rewound to raise the person out of the bath. When the band is being unwound it is important for the band noot to become fully unwound. If the band becomes fully unwound then there is a danger that it will rewind onto the shaft the opposite way round.

According to the present invention there is provided an anti-unwind assembly, the assembly comprises a threaded elongate member rotatable with a winding member, a threaded engagement member mounted on the elongate member, means for preventing rotation of the engagement member such that rotation of the elongate member causes movement of the engagement member therealong, and means for detecting when the engagement member reaches a predetermined position at which position rotation of the winding member ceases.

The apparatus is preferably arranged such that the predetermined position may be adjusted.

The rotation preventing means may comprise an abutment member against which the engagement member is slidably movable, and the abutment member may be in the form of a plate. The abutment member may be selectively movable away from the elongate member to permit the engagement member to be threadably moved along the elongate member to adjust the predetermined position. The abutment member may be pivotally movable.

2 The engagement member may comprise a nut, which nut may be square.

Alternatively, the engagement member may be profiled to accept the abutment member in a recess in the engagement member. The engagement member may be shaped to extend on either side of the plate.

The detecting means may be arranged to engage with the engagement member when in the predetermined position, and the detecting means may comprise a microswitch. The detecting means is preferably arranged to automatically stop rotation of the winding member upon the engagement member reaching the predetermined position.

The detecting means may have an inclined part with which a contact part of the engagement member is engageable, and the relative height of the contact part may be varied such that the predetermined position can be adjusted. The contact part may comprise a screw, and means may be provided for locking the screw in a required position.

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:Fig. 1 is a diagrammatic perspective view of a first assembly according to the invention; Fig. 2 is a diagrammatic side view of the assembly of Fig. 1; Fig. 3 is a diagrammatic opposite perspective view of a second assembly according to the invention; and Fig. 4 is a diagrammatic end view of the assembly of Fig. 3.

Figs. 1 and 2 of the drawings show a first anti-unwind assembly 10 on a bath lift 12 (only part shown). The lift 12 comprises a band 14 of material extendable over a bath and selectively windable onto or off a shaft 16. The assembly 10 is arranged to prevent full unwinding and hence potential rewinding the other way round, of the band 14 on the shaft 16.

3 The assembly 10 comprises a threaded bar 18 which coaxially extends from the shaft 16. An engagement member in the form of a square nylon nut is threadably mounted on the shaft 16. An upstanding abutment plate 22 is provided adjacent the bar 18, and against which the nut 20 is engageable to prevent rotation thereof. A microswitch 24 is mounted on the plate 22 below the bar 18, and is connected to the motor control (not shown) of the lift 12.

In use, as the shaft 16 is rotated to unwind the band 14, rotation of the bar 18 will cause the non-rotating nut 20 to move to the left as shown in the drawings until the nut 20 engages the inclined strip 26 of the microswitch 24.

At this point the lift motor will automatically switch off to prevent full unwinding and potential rewinding of the band 14.

The plate 22 may be pivotally or otherwise movably mounted so as to selectively permit rotation of the nut 20 when the plate 22 is clear thereof, such that the position of the nut 22 on the threaded bar 18 can be varied to adjust the point at which the motor will be switched off.

Figs. 3 and 4 show a second anti-unwind assembly 30 which operates in a generally similar manner, and only the differences will be highlighted. In this instance the engagement member is in the form of a profiled member 32. The member 32 has a top cross part with a downwardly facing slot 34 which slidably mounts a similar plate 36. On the right hand side of the plate 36 as shown in Fig. 4, a downwardly extending finger 38 of the member 32 has a threaded hole through which the bar 18 extends. The member 32 on the left hand side of the plate 36 extends below the finger 38 and includes a recess 40 which accepts the microswitch 24 which is on the opposite side of the plate 22 relative to the assembly 10. A screw 42 extends into the recess 40 from the top of the plate 36 selectively to be engageable with the strip 26 (omitted from Fig.

4 for clarity) of the microswitch 24.

The assembly 30 operates in a similar manner with the profiled member 32 moving outwardly as the band 14 is unwound from the shaft 16. Eventually 4 the screw 42 will come into contact with the strip 26 to actuate the microswitch 24 and hence turn off the lift motor.

The precise position at which the motor is switched off can be varied by adjusting the height of the screw 42 such that it contacts the inclined strip 26 at a different point. A further screw (not shown) may be provided engageable through a lateral hole 44 towards the top of the member 32 on the left hand side as shown in Fig. 4, to engage with the screw 42 to prevent accidental movement thereof.

Various other modifications may be made without departing from the scope of the invention. For example, other means may be provided to prevent rotation of the nut or other engagement member.

The assemblies thus described provide simple yet effective and reliable arrangements to prevent full unwinding of the band, and which arrangements can be readily adjusted as conditions dictate.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

7

Claims

1. An anti-unwind assembly, the assembly comprising a threaded elongate member rotatable with a winding member, a threaded engagement member mounted on the elongate member, means for preventing rotation of the engagement member, such that rotation of the elongate member causes movement of the engagement member therealong, and means for detecting when the engagement member reaches a predetermined position at which position rotation of the winding member ceases.

2. An assembly according to claim 1, wherein the apparatus is arranged such that the predetermined position can be adjusted.

3. An assembly according to claims 1 or 2, wherein the rotation preventing means comprises an abutment member against which the engagement member is slidably movable.

4. An assembly according to claim 3, wherein the abutment member is in the form of a plate.

5. An assembly according to claims 3 or 4, wherein the abutment member is selectively movable away from the elongate member to permit the engagement member to be threadably moved along the elongate member to adjust the predetermined position.

6. An assembly according to claim 5, wherein the abutment member is pivotally movable.

7. An assembly according to any of the preceding claims, wherein the engagement member comprises a nut, which may be square.

8 An assembly according to any of claims 1 to 4, wherein the engagement member is profiled to accept the abutment member in a recess in the 6 engagement member.

9. An assembly according to claim 8, wherein the engagement member is shaped to extend on either side of the plate.

10. An assembly according to any of the preceding claims, wherein the detecting means is arranged to engage with the engagement member when in the predetermined position.

11. An assembly according to claim 10, wherein the detecting means comprises a microswitch.

12. An assembly according to claims 10 or 11, wherein the detecting means is arranged to automatically stop rotation of the winding member upon the engagement member reaching the predetermined position.

13. An assembly according to any of claims 10 to 12, wherein the detecting means has an inclined part with which a contact part of the engagement member is engageable.

14. An assembly according to claim 13, wherein the relative height of the contact part may be varied such that the predetermined position can be adjusted.

15. An assembly according to claim 14, wherein the contact part comprises a screw, and means may be provided for locking the screw in a required position.

16. An anti-unwind assembly, the assembly being substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

17. An anti-unwind assembly, the assembly being substantially as hereinbefore described with reference to Figs. 3 and 4 of the accompanying 7 drawings.

18. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.