GB2247046A

GB2247046A - A load operating mechanism

Info

Publication number: GB2247046A
Application number: GB9018180A
Authority: GB
Inventors: John Willmott; Michael John Spencer
Original assignee: Nuaire Ltd
Current assignee: Nuaire Ltd
Priority date: 1990-08-18
Filing date: 1990-08-18
Publication date: 1992-02-19
Also published as: GB9018180D0

Abstract

A load operating mechanism, for a load (2) pivotted about a horizontal line, comprises a pivoted wedge (3) having an operative end 5 engageable with the load 2 and a profiled edge (6) extending between its axis of pivot 4 and its operative end 5, a first linear actuator (8) having a wheel 7 which acts against the profiled edge (6) so that activation of the actuator (8) urges the operative end 5 of The wedge (3) against the load (2) and a cable (11) which is attached to the load (2), extends around a fixed pulley (13) and wheel (7) and is attached to a second linear actuator (12). Activation of actuator (12) serves to urge the load (2) in the direction opposite to that in which it is urged by activation of actuator (8) and serves to retract actuator (8). The actuators are pneumatic or hydraulic. Actuator 8 may be a sealed gas spring. Actuator 12 may be a pneumatic cylinder controlled by a smoke detector, fire alarm or manual switch. The load operating mechanism may be a window, shutter or hatch opening mechanism. The cable may include rope, wire, string or twine or belting. <IMAGE>

Description

A LOAD OPERATING MECHANISM This invention relates to a load operating mechanism, e.g. a window, shutter or hatch opening mechanism.

According to this invention there is provided a load operating mechanism, the load being pivotted about a horizontal line, the mechanism comprising a wedge pivotted about an axis parallel to said horizontal line, the wedge having an operative end engageable with the load and having a profiled edge extending between its axis of pivot and its operative end, a first linear actuator which acts against the profiled edge to urge the operative end of the wedge against the load, the first actuator including a wheel which engages said edge, a fixed pulley, a cable which is attached to the load, extends around the pulley and the wheel and is attached to a second linear actuator, activation of the second linear actuator serving to urge the load in the direction opposite to that in which it is urged by the first actuator and serving to retract the first actuator.

The term "cable" is to be understood to include any rope, wire, string or twine or belting.

The first and second linear actuators, which may be considered as the opening and closing actuators, preferably act in parallel but opposite directions.

The load may be horizontal or close to horizontal (either above or below) when the operating mechanism is not operated, but might well be at a relatively small angle to the vertical. The force required to be exerted by the wedge against the load to operate that load may largely occur during the first part of the movement of the load. The profiled edge can be arranged to be such as to ensure that the mechanical advantage is very great during the first part of the movement of the load. This is advantageous if the load is a shutter to be opened from an approximately horizontal position.

The actuators are preferably pneumatic or hydraulic.

The first linear actuator may be a sealed gas spring.

Preferably the axis of the wedge is below the pivot line of the load and is laterally spaced from said pivot line on the same side as the load. Depending on the load the axis of the wedge could be on the side of the pivot line of the load opposite that of the load or directly below the said pivot line.

A load operating mechanism in accordance with this invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a side view of the operating mechanism; and Figure 2 is a more detailed side view of a wedge forming part of the operating mechanism of Figure 1.

Referring to the drawings, the load operating mechanism is designed to open a smoke ventilator for a building e.g. a factory.

The operating mechanism comprises a horizontal, open and rectangular base 1 to which there is pivotted at one end, one end of a rectangular load 2 in the form of a flap or shutter. The operating mechanism is intended to be operated in the event of fire to release smoke from a portion of a factory, warehouse or other building to atmosphere. The operating mechanism comprises a wedge 3 at its lower end pivotted about a pivot 4, the pivot 4 being horizontal and supported by the base 1 below the pivotted end of the load 2 and to one side of the pivotted end of the load 2. At its upper, free, end the wedge 3 carries a roller 5 which engages the lower surface of the load 2. Between its pivotted and free ends, the wedge 3 is formed with a profiled edge 6 engaged by a roller 7 carried by an opening actuator 8 shown only schematically in Figure 1.The wedge 3 is shown in more detail in Figure 2 and the shape of the profiled edge 6 can be seen clearly there. In Figure 2, the pivotted and free ends of the wedge 3 are denoted at 9 and 10. One end of a flexible cable 11 extends around a fixed pulley 13, carried by the base 1 and around the roller 7 and is attached to a closing linear actuator 12. Both the opening actuator 8 and the closing actuator 12 operate in the horizontal direction are carried by the base 1. The actuators 8 and 12, do of course, act in opposite directions.

The actuator 8 is a compressed gas-type spring; the actuator 12 is a pneumatic cylinder controlled by a smoke detector, fire alarm or manual switch. On enabling of the opening actuator 8 by de-energising the actuator 12, the roller 7 is pushed against the profiled edge 6 rotating the wedge 3 so that the wheel 5 pushes against the load 2 and rotates it about its end pivot at its edge.

The actuator 8 pushes against the profiled edge 6 to the extent that the load 2 is fully opened. The load 2 is such that much more force is required during the initial angular movement of the load and the profiled edge 6 is such as to create the required mechanical advantage for the initial movement of the load. When the load 2 is to be closed, the actuator 12 is operated pulling on the flexible cable 11 compressing the actuator 8 which is a compressed gas-type spring. When actuator 12 is operated, the cable 11 directly pulls the load 2 to its horizontal position, pushing directly against the roller 5, thereby bringing the wedge 3 back to its original position.

Because the cable 11 passes over the roller 7 it acts directly on the piston of the gas opening actuator 8 thereby bringing it to its closed position directly and not indirectly.

Although the load i.e. shutter 2 is shown horizontal in its closed position, many shutters are not in fact horizontal in their closed positions but may be at an angle to the horizontal. In this case, the initial force required to operate the load 2 is changed and the differential between the initial force required to the force required in the latter part of the movement is not so great and the profiled edge 6 can be changed to accommodate this. Moreover, the position of the pivot 4 can be changed also changing the mechanical advantage and, of course, the relationship of the position of the pivot 4 to the pivotted edge of the load 2 has an affect on the initial force required and therefore on the required shape of the profiled edge 6.

Claims

1. A load operating mechanism, the load being pivotted about a horizontal line, the mechanism comprising a wedge pivotted about an axis parallel to said horizontal line, the wedge having an operative end engageable with the load and having a profiled edge extending between its axis of pivot and its operative end, a first linear actuator which acts against the profiled edge to urge the operative end of the wedge against the load, the first actuator including a wheel which engages said edge, a fixed pulley, a cable which is attached to the load, extends around the pulley and the wheel and is attached to a second linear actuator, activation of the second linear actuator serving to urge the load in the direction opposite to that in'which it is urged by the first actuator and serving to retract the first actuator.

2. A load operating mechanism according to claim 1 wherein the first and second liner actuators act in parallel but opposite directions.

3. A load operating mechanism according to claim 1 or claim 2 wherein the actuators are pneumatic or hydraulic.

4. A load operating mechanism according to claim 3 wherein the first linear actuator is a sealed gas spring.

5. A load operating mechanism according to any of claim 1 to 4, wherein the wedge carries at its operative end a roller which engages the load.

6. A load operating mechanism according to any of claims 1 to 5 wherein the axis of the wedge is below the pivot line of the load and is laterally spaced from said pivot line on the same side as the load.

7. A load operating mechanism substantially as hereinbefore described with reference to the accompanying drawings.