GB1580050A

GB1580050A - Ventilators

Info

Publication number: GB1580050A
Application number: GB20611/76A
Authority: GB
Original assignee: Colt International Ltd
Current assignee: Colt International Ltd
Priority date: 1976-05-19
Filing date: 1976-05-19
Publication date: 1980-11-26
Also published as: NL7705484A; AU2523677A

Description

(54) IMPROVEMENTS RELATING TO VENTILATORS (71) We, COLT INTERNATIONAL LIMITED, a British Company of New Lane, Havant, Hampshire PO9 2LY 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: The present invention relates to ventilators and concerns ventilators of the kind comprising hinged flaps movable between open and closed positions.

Roof mounted fire ventilators are known comprising a flap or a pair of hinged flaps which control ventilation opening, the flap or flaps being arranged to be opened automatically in the event of a fire, to exhaust smoke and hot gases. The flap or flaps may also be arranged to be opened under manual control to provide normal, clear opening, day-to-day ventilation.

In order that the flap or flaps shall open automatically, it is preferred that each flap be urged to its open position by a spring force sufficient to open the flap under the most adverse snow load conditions likely to be encountered.

The flap or flaps are restrained by holding means against opening under normal conditions and released by the holding means for automatic opening upon the onset of a fire condition.

It is also preferred to provide pneumatic actuator means which is operable by means of a selective control to open and close the flap or flaps to provide for normal, clear opening, day-to-day ventilation, and such means may restrain the flap or flaps against automatic opening in the absence of a fire condition.

The ventilator control system which has been adopted for hinged flap ventilators comprises flap opening and closing springs and a pneumatic actuator operable to assist the flap opening springs to overcome the flap closing springs and move the flaps to their open position for normal, clear opening, day-to-day ventilation, the flaps being released by their holding means for automatic opening by the opening springs in the event of a fire being detected.

A problem which arises with hinged flap ventilators is the problem of maintaining the flaps in a tight closed position where, under conditions of use of the ventilator, wind blowing over the ventilator, or over the roof structure on which the ventilator is mounted, gives rise to a pressure differential or suction effect tending to open the ventilator flaps.

There is additionally, a security problem when hinged ventilator flaps of roof mounted ventilators are easy to force open from the outside of the roof structure.

The present invention provides a ventilator comprising a frame, at least one flap hinged to the frame for opening and closing movement, and, for the or each flap, an opening spring connected between the frame and the flap and urging the flap to an open position and mechanism for locking the flap in its closed position, said opening spring being connected between said frame and said flap by means including a lost motion connection, the operation of the opening spring to take up lost motion in said lost motion connection, prior to said opening spring opening said flap, being used to unlock the locking mechanism.

Preferably, the ventilator further includes a closing spring connected between the frame and the flap and urging the flap to its closed position, a pneumatic actuator selectively operable to assist the flap opening spring to overcome the flap closing spring and move the flap to an open position, and release means responsive to a fire condition for releasing the flap from the closing spring and the actuator for automatic opening movement by the opening spring.

Further optional features of the present invention will become clear from a consideration of the following description of one spccific embodiment thereof, given by way of example and not by way of limitation with reference to the accompanying drawings in which: Fig. 1 is a cross-sectional view of a ventilator in accordance with the present invention, Fig. 1A is part of Fig. 1 to a larger size, Fig. 2 is a cross-section of the ventilator, and Fig. 3 shows a detail of the ventilator in the direction of arrow 3 in Fig. 2.

With reference to the accompanying drawings, the ventilator comprises a frame 10 defining a pair of ventilation openings 12, extending over the full length of the ventilator, as seen in Fig. 2. and separated at the centre by a longitudinally extending rain channel 14 forming part of the frame 10. The frame of the ventilator is of double skinned, sheet metal construction and the skins encase foamed insulating material.

Each opening 12 is controlled by a hinged flap or lid 20, hinged as at 21, along the adjacent longitudinal side edge of the frame 10. The flap is of transversely curved shape and. in its closed position, as shown in Fig. 1, it covers over and closes the opening 12 so as to render the ventilator waterproof.

A torsion spring A is anchored at one end in a fitting 24 attached to the adjacent side wall of the frame 10.

The spring extends from the fitting 24.

longitudinally in the opening 12. to a journal bearing 25 in a bracket 26 mounted on a chassis bar 27 disposed transversely of, and spanning the frame 10 intermediate its length. the chassis bar 27 supporting the rain channel 14 and one end of a straight line pneumatic actuator C hereinafter described in detail. The free end portion of the torsion bar spring A is cranked so as to extend normal to, and away from the adjacent flap hinge 21, towards the rain channel 14, and the cranked free end portion of the spring is the spring portion shown in Fig. 1. This crank portion acts simply as an operating arm and not as a spring. the spring force being derived from twisting in the longitudinally extending portion of the spring.

A channel sectioned lever arm G is pivoted as at 30 to a flap frame member 29 spanning the underside of the flap 20. the arm G extending from its pivot. in a plane normal to, and away from. the flap hinge axis in the same general plane as the plane of the spring operating arm portion of the spring A. The arm G is free to pivot to and fro through a small angle between first and second angular positions. to carry a stop pin 35 mounted transversely at the free end of the arm bctween stops formed by the respective ends of a pair of slots 36 in the flap frame member 29, one of which is shown in Fig. 1. The spring operating arm portion of the spring A engages the arm G towards its free end to urge the pin 35 to the upper ends of the slots 36 and therefore the lever arm G from its first position to its second position.In this second position of the pin, the force of the spring A is transmitted to the flap frame, and therefore to the flap 20, to open the flap. The pin-and-slots connection 35, 36 is a lost motion connection between the spring A and the flap.

A spring pressed detent D is urged by a detent pressing spring E anti-clockwise about a pivotal connection, as at 40, with the flap frame member 29 to engage a hook shaped lever arm portion of the detent under a bar F carried by a bracket 41 mounted in the opening 12 on the side of the rain channel 14. The mechanism D, E, F is a locking mechanism which acts to lock the flap 20 in its closed position, and the flap 20 is shown locked in Fig. 1. The detent D is in the form of a bell crank lever and its other lever arm portion is engaged by the pin 35. Movement of the pin 35 to the upper end of the slots 36 operates the bell crank lever against the action of the spring E to withdraw the hook shaped lever arm portion from under the bar F, thereby unlocking the locking, mechanism D, E, F.

The actuator C is mounted longitudinally beneath the rain channel 14 between the chassis bar 27 and a bracket 50 attached to the underside of the rain channel. The piston rod 51 of the actuator carries a cross-head 52 to which is attached the corresponding ends of four coiled tension springs B disposed, in two pairs, one pair on each side of the actuator C. The springs B extend with their longitudinal axes parallel with the line of the actuator C and their opposite ends arc anchored to a bracket 55 attached to a transverse side wall of the frame 10.

The actuator C is a single acting piston and cylinder. Air under pressure is supplied to the cylinder to extend the piston rod out of the cylinder upon the selective operation of a manual control (not shown). The extension of the piston rod 51 out of the cylinder stretches the springs B. Upon release of the air under pressure in the cylinder. the spring B return the piston to the cylinder inner end.

Alternatively, the actuator C may incorporate its own return spring.

The cross head 52 is further connected by means of a fusible link 60 with a pair of stainless steel cables, one of which is illustrated at 61 in Figs. 1A and 2, one cable being associated with each of the flaps 20.

Thus. the cable end is anchored as at 63 to a transverse pin 64 mounted on the arm G.

associated with the flap. the cable being led around pullcys 65 and 66 in sheaves 67 and 68 carried from the ventilator frame.

In the unactuated condition of the actuator C, as shown in the drawings, the cables are held under tension by the springs B and maintain the lever arms G in their first position with the pins 35 at the lower end of the slots 36. Upon extension of the actuator C, the springs A take up the lost motion in the lost motion connections 35, 36, unlocking the locking mechanisms D, E, F and then the springs A open the flaps.

When the compressed air in the actuator C is exhausted, upon switching the manual control of the actuator to exhaust, the flaps are re-closed by the springs B. A camming face 70 on each hook shaped lever arm portion of each detent D strikes the associated bar F and the detents are rotated, in the case of Fig.

1 clockwise, against the action of the springs E. Thereafter, the springs E rotate the detents to re-engage the hook shaped lever arm portions under the bars F to lock the flaps in their closed position.

If the fusible link 60 parts due to the onset of a fire, the tension in the cables 61 is released thus releasing the flaps from the closing springs B and the actuator C for opening movement by the springs A.

The sheaves 68 are mounted on a rocking lever H pivoted to a bracket 79 mounted on the transverse side wall of the frame 10 opposite that mounting the bracket 55. The rocking lever H equalises the load in the two cables 61 and also compensates automatically for possible stretch in the cables.

WHAT WE CLAIM IS: 1. A ventilator comprising a frame, at least one flap hinged to the frame for opening and closing movement, and, for the or each flap, an opening spring connected between the frame and the flap and urging the flap to an open position and mechanism for locking the flap in its closed position, said opening spring being connected between said frame and said flap by means including a lost motion connection, the operation of the opening spring to take up lost motion in said lost motion connection, prior to said opening spring opening said flap, being used to unlock the locking mechanism.

2. A ventilator as claimed in claim 1 further including a closing spring connected between the frame and the flap and urging the flap to its closed position, a pneumatic actuator selectively operable to assist the flap opening spring to overcome the flap closing spring and move the flap to an open position, and release means responsive to a fire condition for releasing the flap from the closing spring and the actuator for automatic opening movement by the opening spring.

3. A ventilator as claimed in claim 1 or 2 wherein the connecting means comprises a lever arm pivoted to the flap. the lever arm being free to pivot between a first angular position relative to the flap and a second angular position relative to the flap in which a stop on the lever arm engages a stop on the flap, and the flap opening spring acts on the lever arm in the sense to pivot the lever arm from its first position to its second position, the lever arm, in so moving, acting to unlock the locking mechanisms.

4. A ventilator as claimed in claim 3 wherein the stop on the lever arm is a pin carried by the lever arm, the pin moving between the opposite ends of a slot in a frame member forming part of the flap and engaging the frame member in each of said angular positions of the lever arm.

5. A ventilator as claimed in claim 3 or 4 wherein the locking mechanism comprises a pivoted detent carried by the flap, the detent engaging under a bar carried by said frame to lock the flap in its closed position and movement of said lever arm from its first position to its second position pivots said detent in one direction to disengage the detent from the bar.

6. A ventilator as claimed in claim 5 wherein a detent pressing spring urges the detent to pivot in the opposite direction to engage the detent under the bar when the flap is moved from an open to its closed position and the detent has a camming surface which engages the bar as the flap is moved to its closed position, the bar then acting to pivot the detent against the action of its pressing spring.

7. A ventilator as claimed in claims 4 and 5 or claims 4, 5 and 6 wherein said pin engages said detent to pivot the detent in said one direction to disengage the detent from the bar.

8. A ventilator as claimed in any one of claims 3 to 7 wherein the lever arm extends from its pivot in a plane normal to, and away from, the flap hinge axis.

9. A ventilator as claimed in any one of claims 3 to 8 wherein the opening spring is a torsion spring anchored to said frame, the spring having a crank which engages said lever arm.

10. A ventilator as claimed in claim 9 including a bearing carried on a support bar connected to the frame, the bearing journalling the torsion spring.

11. A ventilator as claimed in claim 2 and any one of claims 3 to 10 wherein the closing spring acts on the lever arm in the sense to pivot the lever arm from its second position to its first position.

12. A ventilator as claimed in claim 11 wherein the closing spring is connected to the lever arm by a cable and said release means is a fusible link.

13. A ventilator as claimed in claim 12 wherein there are two of said flaps each having an operating cable, said flaps being hinged respectively along opposite sides of said frame. and the pneumatic actuator is

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. In the unactuated condition of the actuator C, as shown in the drawings, the cables are held under tension by the springs B and maintain the lever arms G in their first position with the pins 35 at the lower end of the slots 36. Upon extension of the actuator C, the springs A take up the lost motion in the lost motion connections 35, 36, unlocking the locking mechanisms D, E, F and then the springs A open the flaps. When the compressed air in the actuator C is exhausted, upon switching the manual control of the actuator to exhaust, the flaps are re-closed by the springs B. A camming face 70 on each hook shaped lever arm portion of each detent D strikes the associated bar F and the detents are rotated, in the case of Fig.

carried by the frame and has a cross-head connected to operate said cables.

14. A ventilator as claimed in claim 13 wherein the cables pass around pulleys in sheaves mounted on a rocking lever carried by the frame which lever acts to equalise the load in the cables and to compensate for any stretch therein.

15. A ventilator substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.