GB1559148A

GB1559148A - Sliding doors

Info

Publication number: GB1559148A
Application number: GB5310777A
Authority: GB
Original assignee: Hunt & Baird Pty Ltd
Current assignee: Hunt & Baird Pty Ltd
Priority date: 1977-12-21
Filing date: 1977-12-21
Publication date: 1980-01-16

Description

(54) SLIDING DOOR (71) We, HUNT & BAIRD PTY. LTD., of 260 Musgrave Road, Coopers Plains, Queensland 4108, Australia, a Company incorporated under the Laws of the State of Queensland, Australia, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an electricallyoperated sliding door mechanism.

Previous doors of this kind have attached the door to a top wire or chain driven by a motor via a pulley round which the top drive member is looped.

Such a door is not easily moved manually with motor unenergized owing to resistance to movement of the top drive member on the pulley.

In one prior door, the top drive member is provided with extension springs so that on manual operation a spring will be extended and loosen the drive wire on the pulley. Such an arrangement still resists manual operation to an undesirable extent and tends to be unreliable.

An object of this invention is to provide an electrically-operated door which is entirely free to be moved manually when the motor is inoperative.

Further objects of the invention are to enable reversing of door movement at any position of the door and to provide auto matic stopping of movement if the door encounters an obstacle.

The invention in one aspect comprises a sliding door mechanism including a flexible drive member to which the door is attached, an electrical motor, driving means driven by said motor and driving said member, an electrically-operated clutch between said motor and said driving means, and an electrical supply for activating said motor and engaging said clutch simultaneously.

With this arrangement the clutch is engaged whenever the motor is activated, and is disengaged when the motor supply is cut off, so that the door can be freely moved manually.

The clutch may have switching means to disengage it, but not the motor, when the door encounters an obstacle.

In order that the invention may be better understood, a specific arrangement will now be described with reference to the accompanying drawings, in which: FIG. 1 is a front view of the door and frame (the door being in the closed position), FIG. 2 is an enlarged detail front view of the door operating mechanism: and FIG. 3 is a side elevation of Fig. 2.

Door 1 is slidably mounted on runners 2 fixed to frame 3 of a coolroom by grooved rollers 4 in the standard manner.

An electric motor 5 is mounted on the top of the coolroom frame 3. An electrical clutch 6 having a driven hub 7 and a driving pulley 8 is fitted to the motor via hub 7 being drivingly secured to shaft 9 of the motor. Driven hub 7 and driving pulley 8 are freely rotatable relative to each other when clutch 6 is unenergised, but are connected to common rotation when energised.

A pair of idler pulleys 10 are rotatably mounted on the frame 3. The idler pulleys 10 are horizontally and vertically aligned with each other, and are vertically aligned but spaced from the electrical clutch 6.

The door 1 is fitted with a pair of horizontal extension assemblies 11, each secured to a top corner of the door. Both assemblies 11 are provided with a belt securing clamp 12 to secure one of the free ends of a transmission V-belt 13 to an assembly 11. The V-belt 13 is looped around the idler pulleys 10 and driving pulley 8 of the electrical clutch 6, the belt being in the form of a Greek "omega".

The electrical control circuit of the electrical clutch 6 is wired so that clutch 6 is engaged only when electricity is supplied to the motor 5, allowing the motor 5 to be reversed at any position of the door 1 without disengaging the clutch 6.

A switch is included in the latch control circuit only, operable when the door encounters an obstacle during its travel to disengage the clutch and thus stop movement of the door. This switch may be automatically opened by an increase in motor current due to increased motor load and may have a time delay in it to prevent false operation.

Limit switches 14 are fitted to the coolroom frame 3 to disconnect the electrical supply to the motor 5 and the clutch 6 when the door 1 is at the end of its allowable travel along runners 2.

The operation of the sliding door will now be described.

Figure 1 shows the door in the closed position. To open the door 1, the electrical supply to the motor 5 is switched on and clutch 6 is energised. Clockwise rotation of motor shaft 9 is transmitted to driving pulley 8 as the clutch is engaged, and the V-belt 13 is drawn from left to right around the idler pulleys 10 and driving pulley 8, thereby opening the door. When the door 1 reaches the limit of its travel on the runners 2, a limit switch 14 is engaged which switches off the electrical supply to the motor, simultaneously disengaging the clutch 6. To close the door, the procedure described is followed but the motor 5 is operated to rotate the clutch 6 in an anticlockwise direction.

If the door 1 is to be moved manually while the motor 5 is switched off or inoperative, the door can be easily pushed or pulled in the desired direction as the clutch 6 is now disengaged. The motor 5 does not offer any resistance to movement of the door as driving pulley 8 is now freely rotatable relative to driven hub 7 on the motor shaft 9 while clutch 6 is disengaged.

The safety switch in the clutch control circuit cuts off the electrical supply to the clutch 6 when the door encounters an obstacle, disenergising and so disengaging the clutch to prevent damage to the door and the drive mechanism.

In an alternative form of safety switch, the door 1 is fitted with a safety strip on the leading edge of the door. If on closure, the door's leading edge encounters an obstacle, the door will on contact automatically stop and/or change direction.

Various changes and modifications may be made in the arrangement described and claimed without departing from the invention.

WHAT WE CLAIM IS: 1. A sliding door mechanism including a flexible drive member to which the door is attached, an electrical motor, driving means driven by said motor and driving said member, an electrically-operated clutch between said motor and said driving means, and an electrical supply for activating said motor and engaging said clutch simultaneously.

2. A sliding door mechanism as claimed in Claim 1 wherein said driving means and said clutch include a driven hub fixed on a shaft of the motor, and a driving pulley driving the flexible drive member, the hub and the pulley being freely relatively rotatable when the clutch is unenergised, but which are connected for common rotation when the clutch is energised.

3. A sliding door mechanism as claimed in Claim 2 wherein the flexible drive member is a transmission V-belt.

4. A sliding door mechanism as claimed in Claim 3 wherein the free ends of the belt are fixed to the door and the belt is looped round two free pulleys and over the driving pulley, the belt being in the form of a Greek "omega".

5. A sliding door mechanism as claimed in any one of the preceding claims including switching means to disengage the clutch, but not the motor, when the door encounters an obstacle.

6. A sliding door mechanism as claimed in Claim 5 wherein the switching means is operated by an increase in motor current due to increased motor load.

7. A sliding door mechanism as claimed in any one of Claims 1 to 4 wherein a leading edge of the door is provided with a safety strip, the safety strip operating switching means to disengage the clutch when the leading edge of the door encounters an obstacle.

8. A sliding door mechanism substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The electrical control circuit of the electrical clutch 6 is wired so that clutch 6 is engaged only when electricity is supplied to the motor 5, allowing the motor 5 to be reversed at any position of the door 1 without disengaging the clutch 6. A switch is included in the latch control circuit only, operable when the door encounters an obstacle during its travel to disengage the clutch and thus stop movement of the door. This switch may be automatically opened by an increase in motor current due to increased motor load and may have a time delay in it to prevent false operation. Limit switches 14 are fitted to the coolroom frame 3 to disconnect the electrical supply to the motor 5 and the clutch 6 when the door 1 is at the end of its allowable travel along runners 2. The operation of the sliding door will now be described. Figure 1 shows the door in the closed position. To open the door 1, the electrical supply to the motor 5 is switched on and clutch 6 is energised. Clockwise rotation of motor shaft 9 is transmitted to driving pulley 8 as the clutch is engaged, and the V-belt 13 is drawn from left to right around the idler pulleys 10 and driving pulley 8, thereby opening the door. When the door 1 reaches the limit of its travel on the runners 2, a limit switch 14 is engaged which switches off the electrical supply to the motor, simultaneously disengaging the clutch 6. To close the door, the procedure described is followed but the motor 5 is operated to rotate the clutch 6 in an anticlockwise direction. If the door 1 is to be moved manually while the motor 5 is switched off or inoperative, the door can be easily pushed or pulled in the desired direction as the clutch 6 is now disengaged. The motor 5 does not offer any resistance to movement of the door as driving pulley 8 is now freely rotatable relative to driven hub 7 on the motor shaft 9 while clutch 6 is disengaged. The safety switch in the clutch control circuit cuts off the electrical supply to the clutch 6 when the door encounters an obstacle, disenergising and so disengaging the clutch to prevent damage to the door and the drive mechanism. In an alternative form of safety switch, the door 1 is fitted with a safety strip on the leading edge of the door. If on closure, the door's leading edge encounters an obstacle, the door will on contact automatically stop and/or change direction. Various changes and modifications may be made in the arrangement described and claimed without departing from the invention. WHAT WE CLAIM IS:

1. A sliding door mechanism including a flexible drive member to which the door is attached, an electrical motor, driving means driven by said motor and driving said member, an electrically-operated clutch between said motor and said driving means, and an electrical supply for activating said motor and engaging said clutch simultaneously.