Safety device for doors of pressurised containers

Agent (s): Cabinet Aimengaud Jeune. Casanova and Lepeudry.

S4) Safety device for pressure contai ner doors.

FR 2 SS4 699 - A3 t The invention relates to the safety of the use of pressure vessels.

A lock 16 engages in a keeper 25 and is controlled by a crank 14 secured to a rotating handle 13 and a connecting rod 15. A piston 23 pushed by the internal vapor pressure, initially blocks the crank 14. After the fall of the pressure, the handle is turned in the direction of the arrow to partially release the lock 16 with conical end and let the residual steam escape around the periphery of the door. A claw 19 'retains the crank 14 by its tooth 17. A reverse movement of the handle allows the spring 20 to release the crank 14 from the claw 19 and a new rotation of the handle in the first direction fully releases the lock.

Main application: pressure cookers for communities.

<img file="FR2554699A3_D0001.tif" />

D

Sale of booklets at IMPRIMERIE NATIONALE, 27, nie de la Convention - 75732 PARIS CEDEX 15

The present invention relates to a security devi ce for doors of pressure receptacles which open towards the outside, in particular for steam cooking ovens for communities. As is known, there are specific standards which make it necessary to protect the user against the risks which may result from the opening of devices of this type when the vapor which is contained therein has a pressure greater than a determined limit. On the basis of these standards, two different types of safety devices can be produced.

A first type, called multiple operation, normally provides for the use of at least two lever mechanisms and pressure control by the user by means of a pressure gauge. It appears obvious that, in this case, safety is above all entrusted to the attention and diligence of the user, who must activate the opening devices without losing sight of the pressure gauge. Indeed, in the event of a false operation, the opening of the door could occur quickly under the effect of the residual pressure of the vapor contained in the container, causing serious dangers for the user, who would be subjected to the action of a steam jet.

A second type of security provides for the use of a closing and opening device known as a single operation. In this case, the pressure gauge has purely an indication function, while the lever device must be controlled by an automatic device which prevents it from being actuated before the steam pressure inside the device has fallen to sufficiently reduced values.

Various solutions are known for this second type of security, which is certainly more advantageous than the first.

One solution includes the use of a hook located on the outside of the door and an elastic lip seal placed between the edge of the door and the edge of the appliance opening. The internal pressure of the container expands the packing, preventing actuation of the hook, which, on the contrary, is only authorized when the pressure is very low and the packing can be compressed. This solution has drawbacks and difficulties resulting from the fact that the lining can be compressed, even if the relative pressure inside the appliance is not entirely brought back to zero; in addition, the trim can retain in its lower zone solid and liquid substances which must be removed periodically so as not to jeopardize subsequent closings of the door.

Another solution provides for the production of a double-walled door, the external wall being rigid and the internal wall being floating and capable of being deformed under the action of the internal pressure of the vapor. Between the two walls, the release mechanism of the external opening lever is placed while a lining is mounted along the periphery of the door and forms a tight seal against the edge of the container opening. This solution also has drawbacks due to the fact that the interior wall of the door is necessarily large and that its progressive displacement can attack the opening lever before the relative pressure inside the device has reaches a zero value, thus allowing opening with steam outlet.

The object of the invention is to provide a closing and safety device for doors of pressure receptacles opening towards the outside which guarantees the absolute safety of the user by not allowing the complete opening of the door. only when the relative pressure inside the device has effectively been canceled.

This object is achieved by a safety device consisting of a mechanism controlled by a single lever but which is adapted to be actuated by maneuvers controlled in sequence.

The safety device according to the invention comprises a handle articulated on the container door and secured to a crank, which is controlled by a blocking element and is connected by means of a connecting rod to a lock for closing the door, device characterized in that a claw cooperating with said crank is biased by a spring to take two different end positions which correspond respectively to the open and closed positions of said latch, said claw being adapted to engage with a tooth formed on said crank to assume an intermediate position between the two end-of-travel positions.

The device according to the invention requires for the opening of the door a first rotation of the crank in one direction, so as to hook the claw by the crank and partially release the lock, a second rotation of the crank in the opposite direction , so as to unhook the claw from the crank and a third rotation in the same direction as the first to complete the release of the lock.

The figures of the appended drawing, given solely by way of example, will make it clear how the invention can be implemented. In this drawing, Figures 1 to 3 show by partial schematic views the door of the pressure receptacle equipped with the device according to the invention in the different working positions;

4 shows in section the door in the position of FIG. 3.

In the figures there 3, there is shown a pressure container 10 equipped with a door 11 adapted to open towards the outside, by turning around a hinge 12, under the action of an external handle with lever. 13 which is mounted to rotate substantially in the center of the door.

The closing safety device is mounted in the interior volume of the door 11. This device comprises a crank 14 which rotates integrally with the lever 13 and is connected by a connecting rod 15 to the latch 16 of the door. The latter engages in a housing 25 provided on the front side of the device 10 and cooperates with a switch (not shown) which controls the introduction of steam into the container.

The crank 14 is provided at one end with a tooth 17 intended to cooperate with a finger 18 which projects on an arm of a claw 19, which is articulated in the door and urged by a spring 20 hooked in the interior volume of this door. The claw 19 can oscillate between two end-of-travel positions determined by two stops which are constituted respectively by a fixed finger 21 and by the body of a cylinder 22 in which a piston 23 slides. One end of the piston 23 projects into the interior volume of the door 11 to constitute a blocking element for the crank 14 while the other end, directed towards the interior of the container 10, is in contact with an elastic membrane 24 ( figure 4). This membrane closes the cylinder 22 with a seal and transmits the pressure of the vapor to the piston 23 when the container 10 is in service.

The device described operates as follows. In the closed position (Figure 1), the lever handle 13 is in the vertical position, with the crank 14 released from the claw 19, which is turned into the position in which it abuts with its finger 18 against the cylinder 22. The lock 16 is engaged in its housing 25 at the front of the container 10. The piston 23 exits from the cylinder 22, pushed by the pressure of the steam acting on the membrane 24, and it blocks the crank 14.

These conditions remain maintained throughout the period of operation of the apparatus, during which there is pressurized steam inside the container 10.

When the working cycle of the appliance is finished, a normal timer (not shown) allows the steam to discharge from the interior of the container. The piston 23 can therefore enter the cylinder 22, by unlocking the crank 14. At this time, the door opening operation can be triggered. The handle 13 is turned clockwise (according to the arrow in FIG. 1), thus causing the rotation of the crank 14 which, via the connecting rod 15, only partially releases the lock 16. Thanks to its conical end, the latter allows a limited opening of the door 11 and the escape of residual steam in a peripheral and lateral direction relative to the door, therefore without any risk for the user.

This partial opening situation under safety conditions is ensured by the connection between the tooth 17 of the crank 14 and the finger 18 of the claw 19 (FIG. 2). This grip is caused by the rotation of the crank 14 together with the lever 13, rotation which pushes the finger 18 along the edge of the crank, by rotating the claw 19 anticlockwise. .

To fully open the door 11, when the pressure relative to the interior of the container has effectively been canceled, the handle 13 must be turned anticlockwise (according to the arrow in FIG. 2) so as to cause a similar rotation of the crank 14, until releasing the finger 18 from the tooth 17. Consequently, the claw 19 is returned by the spring 20 to its second end-of-travel position in which it abuts against the finger 21. At this stage, the handle 13 is again made to rotate clockwise, and the crank 14, being free to rotate, controls the unlocking of the lock 16 (FIG. 3), thereby authorizing the opening of the door.

To conclude, the device according to the invention 5 realizes the opening of the door in two distinct phases using a lever handle actuated by maneuvers controlled in a sequence, by authorizing total opening only when the pressure inside the container has actually dropped to zero. This device therefore prevents the user from having to pay particular attention. It is simpler in construction and operates both safely and conveniently.

It goes without saying that modifications may be made to the embodiment which has just been described, in particular by substitution by equivalent technical means, without thereby departing from the scope of the invention.