GB2121873A - Actuating systems for operating doors - Google Patents

Abstract

The present invention relates to actuating systems using a sealed liquified gas container 1 in which the gas is typically carbon dioxide. Means are provided for releasing the gas in response to an electrical signal derived from various sources to close doors, to move loads or to open or close valves in emergency situations. The liquified gas container 1, a piercing member 2, a spring 3 and a spring retaining piston 34 are contained in a replaceable cartridge 5. Situated around an anchor ring 6 is a low power fast response heater 8 which melts a low melting point alloy soldered joint 7 which joins a piston 4 to an anchor ring 6. In operation, pressure from the liquified gas container is released as follows: a signal from a smoke detector or alternative source allows current to flow to the heater to melt the soldered joint 7, allowing pressure from the liquified gas container to move a piston 15 to rotate a lever 30 to close a door. Within the piston 15 is contained a ball 22 and detent arrangement 23 and 26 controlling the position of a valve arrangement comprising a seal 27 and an annulus 25 causing the pressure on either side of the piston 15 to be balanced following the first stroke, thus providing a lower level of resisting and operating forces for subsequent operations. <IMAGE>

Description

SPECIFICATION Improvements in actuating systems The present invention relates to systems which use liquified gas, typically carbon dioxide, stored in a sealed cylindrical gas container, whereby means are provided for piercing the cylinder in response to a signal such as a smoke detector to release gas to an actuating cylinder to cause opening or closing of a door, window or valve. Embodiments of the present invention are particularly suitable for use in emergency and safety systems.

Emergency systems by their nature are required to be inoperative for a long period of time but must have a high probability of working when called upon. In emergency systems such as automatically closing fire doors, the doors are arranged to be latched into an open position normally by means of electro magnetic latches which allow the door to be closed when the circuit is de-energised in response to an electrical signal typically derived from a smoke sensor. The force to close the door is normally provided by means of springs or weights. Such systems are limited by the level of force which can be made available to close the door and also use continuously energised electrical systems which are therefore prone to failure.The present system seeks to provide a door closer capable of providing large closing forces and which is entirely passive until it receives an electrical signal from a smoke sensor.

After initial operation to close the door the force provided by the door closer is greatly reduced enabling easy opening.

In the present invention the door closer is situated adjacent to the door but not attached to it such that it is entirely passive until activated by a signal derived typically from a smoke sensor. The door may be open or latched with a simple spring loaded ball catch or magnetic catch, or remain unlatched and free to move until a pre-determined signal derived from the smoke sensor causes release of the stored energy from a liquified gas container which then, via an actuating device, applies the force to the door to cause it to close.

The gas pressure developed in the actuating cylinder will then continue to apply a force to hold the door closed.

According to one aspect of the invention the liquified gas container, together with a member for piercing the container, are situated in a replaceable cartridge which also contains a spring held in its compressed position by a member reacting the load back to the replaceable cartridge housing by means of a soldered joint. The soldered joint is made using a low melting point alloy.

Situated in the immediate vicinity of the low melting point alloy joint and around the circumference of the replaceable cartridge is a low power heating element. Upon energising the heating element from an electrical supply, activated by a smoke sensor, the low melting point alloy melts causing the spring to apply an impact load to a piercing member causing the liquified gas container to be pierced. The gas from the liquified gas container is transferred to a piston type actuator to which means are attached for transmitting the force applied by the gas pressure to cause the door to close. The use of the soldered joint provides a high reliability retaining element for the gas pressure release mechanism and the use of the low melting point alloy as the solder enables the use of a low power fast response heating element to melt the joint.

Because of its low power, the heating element can be allowed to operate continuously without causing damage and with an acceptable low power drain, which is important when operated from battery systems, without the need to switch off the power. The cylindrical gas container, piercing member, release spring piston and its associated soldered joint are contained within a replaceable cartridge which is used once only, thus eliminating the unreliability due to wear etc, whilst enabling a rapid return to normal operational capability foliowing inadvertent operation due to false alarms.

In one embodiment of the present invention, when the door has reached its near closed position, pressure is connected by means of a valve either formed in the actuating piston or as a separate item, to the rod end side of the piston to reduce the force necessary to open the door. For subsequent opening and closing operations the force will remain at this reduced level. With this arrangement a very large force is provided for the first closing action in order to overcome any resistance to closing which may occur due to the door having been heid open by some form of weight, ball catch or other means. This arrangement provides two different levels of force from the door closer without resort to continuously bleeding gas.

In another embodiment of the present invention the output from the piston is caused to open or close a valve in response to some external signal.

In this case a two-stage force system will not normally be required and a conventional piston is used.

Embodiments of the present invention will be more particularly described by way of example with reference to the accompanying drawings in which Figure 1 shows the construction of a passive door closer, Figure 2 shows a passive door closer in relation to a typical door installation, Figure 3 shows a fast response heater and joint assembly, and Figure 4 shows a construction of a valve actuator.

Figure 1 shows a construction of a passive door closer which is arranged as shown in Figure 2 to close the door in the presence of a fire. Referring to Figure 1, a liquified gas container 1, piercing member 2, spring 3 and spring retaining piston 3L are contained in a replaceable cartridge 5. Spring retaining piston 34 is connected to anchor ring 6 via piston rod 4 and soldered joint 7. Situated around anchor ring 6 is a low power heater 8 which is electrically powered in response to a signal from a smoke detector 37 (Figure 2) via plug and socket 9 and terminal block 10.

In operation, pressure from the liquified gas container is released as follows: a signal from a smoke detector 37 (Figure 2) allows current from a battery, or transformed main current, to flow to the heater 8 which will rapidly melt the soldered joint 7, allowing spring 3 to accelerate piston 34 causing piston rod 4 to strike piercing member 2 to pierce sealed liquified gas container 1. Gas is released into chamber 11 via sealed connector 12 and transfer hole 1 3. The pressure acting on piston 1 5 and piston rod 1 6 rotates pinion 1 7 via rack 1 8 thereby causing rotation of shaft 1 9 and lever 30 which closes the door via roller 44 (Figure 2).

When the door has reached some point in its travel approaching the fully closed condition, movement of piston 1 5 is arrested by face 20.

Prior to this time a very large force was provided by pressure acting on both piston 1 5 and piston rod 1 6, via face 21, enabling the door to move weights or any other objects which may have been used to hold it open in a partiai or fully open position. When piston 1 5 engages with face 20 pressure acting on the end of piston rod 1 6 ioads ball 22 seated in detent 23, causing the ball to move outwards against spring 24 thus allowing piston rod 1 6 to move relative to piston 1 5 until ball 22 engages with detent 25.As piston rod 1 6 reaches the position where ball 22 is engaging into detent 25, annulus 26 passes over seal 27 allowing pressure to be connected from chamber 11 to chamber 28 via slot 38, annulus 26 and transfer hole 29. The pressure forces on piston 1 5 are now balanced and the force finally latching the door is provided by the pressure acting on the area of piston rod 1 6. Therefore for subsequent opening of the door, i.e. to enable occupants of a room to exit through the door without difficulty, a very much reduced force is provided.

As piston rod 1 6 and rack 1 8 are separate components inadvertent movement of lever 30 cannot be transmitted to cause movement of piston 1 5 with the door closer in its normal passive state. The lever 30 can therefore take up any angle without movement of piston 1 5. Doors situated close to walls at right angles can be accommodated without special measures.

There is some variation in the pressure in cylinder chamber 28 as a function of door displacement, both during initial door closing (pressure increasing from atmospheric on rod side of piston) and when the door is subsequently opened (piston rod 1 6 entering chamber 28), but the proportions of the relevant components limit these pressures to small and acceptable vaiues.

When replaceable cartridge 5 is changed piston 1 5 is reset by simply rotating lever 30 to its fullest extent thereby forcing piston 1 5 against face 31 via rack 18 and piston rod 1 t3 causing ball 22 to be re-engaged with detent 23.

Particular features of the fast response heater and joint assembly are shown on Figure 3. A high thermal conductivity heat path having low thermal mass is provided by a thin film 32 of high thermal conductivity material, such as copper, plated onto or bonded onto anchor ring 6 (around the diameter in the vicinity of heater 8 [Figure 1] and at end face 33) which is manufactured from a relatively low thermal conductivity material such as steel or stainless steel. The low melting point alloy joint 7 is therefore made between film 32 and piston retainer 4 which is also manufactured in a low thermal conductivity material. Heater 8 (Figure 1) consisting of a thin foil or wound wire electrical element 35 wrapped round the diameter of the thin film 32 is separated from film 32 by a thin electrical insulating medium 36. Around heater element 35 is wrapped a thermal insulating ring 37. This arrangement provides sufficient surface area to permit the use of relatively low heater element temperatures together with an efficient heat transmission path and a soldered joint of minimum surface area due to the joint being loaded in pure tension. The result is a fast response time for breaking the joint with low heat power.

A further embodiment of the present invention is shown on Figure 4 in which the pressure from liquified gas container 1 is released in a manner similar to that previously described, via the low power fast response heater 8 responding to a signal derived from an external source such as a smoke sensor, temperature measurement device, pressure sensor, gas detector or process controller. The rack 39, to which is attached piston 40, drives shaft 41 via pinion 42 to operate valve 43.

Claims (1)

1. An actuating system comprising a sealed liquified gas container containing high vapour pressure gas such as carbon dioxide, a piercing member incorporating a small thin-walled tube or spike together with a piston and spring retained by a low melting point alloy soldered joint in which a low power fast response heater is provided to melt the said joint in response to an external signal, typically from a smoke sensor, causing electric current to flow to the heater thereby melting the joint and releasing the energy of the spring to cause the liquified gas container to be pierced allowing pressure to a piston in a cylinder which, operating via a transmission mechanism, is caused to close a door.

2. An actuating system, as claimed in claim 1, wherein a valve and positioning mechanism is arranged to cause a balance of pressure across the actuating piston to reduce the actuator output force when the actuating piston has been activated and is approaching completion of its first stroke, thus maintaining lower output and resisting forces for subsequent operations without a continuous bleed of gas.

3. An actuating system as claimed in claims 1 or 2, wherein heat from a low power foil or wire wound electrical heater is conducted to the face of a low melting point alloy joint via a thin high thermal conductivity film situated around the diameter of a reaction member, around which is wrapped the heater element, and leading to one side of a low melting point alloy soldered joint; the thermally conductive film being permanently joined to the reaction member by plating, bonding or similar means.

4. An actuating system as claimed in claims 1, 2 or 3, wherein the transmission between the actuating piston and output member is split to prevent movement of the output member causing movement of the actuating piston in its inoperative state but allowing the valve assembly, which permits a reduced output force to prevail after the first operation, to be reset by moving the output member to the extent of or near to its full travel.

5. An actuating system as claimed in claim 1, wherein the said actuator is caused to open or close a valve, vent, door or window in response to an external signal causing current to flow to the said low power fast response heater.

6. An actuating system substantially as described herein with reference to Figures 1-4 of the accompanying drawings.

New claims or amendments to claims filed on 16th September 1983.

Superseded claims 1.

New or amended claims:

1. An actuating system comprising a sealed liquified gas container containing high vapour pressure gas such as carbon dioxide, a piercing member incorporating a small thin-walled tube or spike together with a piston and spring retained by a low melting point alloy soldered joint in which a low power fast response heater is provided to melt the said joint in response to an external signal, typically from a smoke sensor, causing electric current to flow to the heater thereby melting the joint and releasing the energy of the spring to cause the liquified gas container to be pierced allowing pressure to a piston in a cylinder which, operating via a transmission mechanism, is caused to close a door and in which the gas remains trapped in the cylinder acting as a spring to allow the door to be re-opened and causing it to reclose.