GB2170858A - Door lock for an autoclave - Google Patents

Abstract

A door lock for an autoclave comprises a handle 7 pivotable on an axle 8 journalled in bearing 9 and which engages with racks 12 on slide plates 11 via pinions 13. Slide plates 11 have apertures 16 and recesses 15 to engage behind the heads of bolts (not shown) provided adjacent a chamber opening, to lock the door shut at a plurality of positions with a single pivoting movement of handle 7. Latch 16 engages behind a plate when the handle 7 is closed and can be held there to prevent opening of the handle when the temperature or pressure in the chamber exceeds certain limits. An inner handle 29 behind handle 7 forms an over-centre toggle mechanism with a latch 27, the handle 29 and latch 27 respectively pivoting about axles 26, 28 in the door 1 and handle 29. Handle 29 moves from a closed position (Fig. 2) to a partially open position to allow the door to open, latch member 27 engaging a stop 32 to force the door to open if necessary. Further movement of the handle urges latch 27 against a spring 33 and releases it from a catch 31 to allow the door to be fully opened. <IMAGE>

Description

SPECIFICATION Door lock The present invention relates to door locks, in particular the invention relates to door locks for pressurised vessels such as autoclaves.

In autoclaves which are fed with pressurised steam, the closed vessel is required to withstand a high internal pressure and temperature, typically a test pressure of 60 p.s.i. and a working pressure of 32 p.s.i.. The door locking mechanism incorporates safety devices to prevent opening of the door whilst any substantial residual pressure remains in the autoclave chamber, and also whilst the temperature of any liquid load in the chamber exceeds 80"C. Also the door lock must allow an initial opening of the door, to release any residual pressure and break the seal between the door and chamber, whilst restraining the door from opening completely due to some internal force, for example in the event that there is a high pressure remaining in the chamber.

To meet the pressure requirements an autoclave door is typically locked shut against the autoclave chamber at a plurality of points.

Prior art devices include the use of a plurality of bolts which are mounted to turn freely in the door and which engage in threaded holes provided adjacent the chamber opening. Typically four such bolts are provided, each being turned manually. Another arrangement uses a central wheel which is spun to drive home or release a plurality of locking members. These prior art methods suffer the drawback of requiring a considerable iength of time and force to operate, which may lead to misuse of the apparatus when the operative is in a hurry.

A first aspect of the present invention provides a lock for a door, comprising a plurality of engagement means provided adjacent an opening to be closed by the door, slide plate means slidably mounted on the door and adapted for form-locking connection with the engagement means, and a handle pivotably mounted on the door, the handle being connected to the slide plate means so that, when the door is closed, the handle is pivotable between closed and open positions to slide the plate into and out of form-locking connection with the engagement means to prevent and allow opening of the door.

Preferably, the handle is provided with a latch which is pivotably mounted thereon.

With the handle in the closed position the latch engages behind a catch plate projection, preferably provided on the door. A pin member is preferably arranged to hold the latch against the projection whilst the internal pressure or temperature of the chamber exceeds a predetermined limit.

A second aspect of the invention provides a door lock for locking a container door, comprising a handle mounted on the door to pivot about a first axis, a latch member mounted on the handle to pivot about a second axis spaced from the first axis, a latch plate provided on the container and engageable by the latch member, the latch member and handle forming an over-centre toggle mechanism whereby the handle is movable from a first to a second position to partially open the door with the latch member remaining in engagement with the catch plate, and from the second to a third position to disengage the latch member from the catch plate.

The latch member is preferably biassed against the catch plate. Preferably, stop means are provided on the container, the latch member being urged against the stop means as the handle is moved from the first to the second position, to lever open the door, breaking the seal between door and the container.

It will be appreciated that the door locks defined above may be arranged with the handle and slide plate or latch member mounted on the container, the engagement member or catch being mounted on the door.

The door locks defined above are particularly suitable for use with autoclaves, and very preferably are used in combination to provide a safe and efficient locking mechanism.

The invention further provides a door lock for an autoclave, compri sing first locking means for holding the door closed against an internal pressure and second locking means for holding the door closed as said first locking means is released, wherein a handle for operating the first locking means overlays a handle for operating the second locking means.

With this arrangement it can be made clear to a user that when opening the door, the first locking means must be released before the second locking means, and when closing the door, the second locking means must be activated berfore ths first locking means.

Preferably the handles each comprise a lever. Preferably the handle of the first locking means substantially covers the handle of the second locking means.

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a perpective view of a door including door locks according to the invention; Figure 2 is a cross-section along the line ll-ll of Fig 1, with the door in a closed and locked position against an autoclave chamber; and Figure 3 illustrates a modification of the door shown in Fig. 1.

A door 1 is hinge mounted on a front wall flange 2 of an autoclave chamber 3 by hinges 4.

The door is of stainless steel, as are a chamber wall 5 and the flange 2. An '0' ring 34 forms a leak-tight seal between the door 1 and flange 2. The door 1 has an inner skin 6 secured thereto.

An outer handle 7 is mounted fast on an axle 8 which is journalled in bearings 9 provided on the outer skin 10 of the door. Slide plates 11 are slidably mounted on the door, sliding towards and away from the hinges 4, in collars 24. The slide plates 11 carry racks 12 which are engaged by pinions 13 mounted fast on the axle 8. By pivoting the handle 7 about the axis of the axle 8, the slide plates are slid to the left and right as seen in Figs 2 and 3.

The door 1 has a plurality of holes 14. A plurality of bolt shaped members (not shown) are mounted on the flange 2, and positioned so that the bolt heads project through the openings 14 when the door 1 is closed against the flange 2. The slide plates 11 have recesses 15, 16 which mate against the shanks of the bolts as the slide plates are slid to the right, as viewed in the drawings, the slide plates engaging behind the bolt heads to lock the door against the flange 2 at four positons, in the Fig 1 embodiment, or eight positions, in the figure 3 embodiment. One or a plurality of slide plates may be provided.

Each slide plate may co-operate with one or a plurality of bolts heads.

The outer handle 7 has pivotably mounted thereon a latch member 16 having a tongue 17 which engages behind a catch plate 18 as the handle 7 is swung to the closed position.

The latch is biassed to the position seen in Fig 2 by a light spring (not shown). To release the handle 7, the latch is pressed by finger pressure, at A, to pivot about pivot 19. Two pins 20,21 are arranged on the door 1 and are each slidable into a locking position behind the latch tongue 17 to hold the latch in engagement with the catch plate 18. The pins 20,21 are slid into the locking position by a thermal lock actuator 22 and a pressure lock actuator 23, respectively, when the temperature or pressure in the chamber exceeds a predetermined limit. The pins 21,22 are withdrawn automatically as the temperature and pressure both fall to a safe level.

A catch, not shown, is provided to prevent sliding of the plates 11 to the closed position when the door is open. The catch may be arranged to be released by a bolt head as it enters a hole 14.

An inner handle 25, is pivotally mounted on the door 1 to pivot about a first axis 26. A latch 27 is pivotally mounted on the handle 25, pivoting about a second axis 28.

Handle 25 has a gripping portion 29 formed of thermally insulating or low heat capacity material, such as foamed resin.

Latch 27 has a tongue 30 which engages behind a catch plate 31 provided adjacent the flange 2. Catch plate 31 may be formed in the flange 2. A stop 32 is provided proximal of the end of the tongue 30. A spring 33 biasses the 1 atch plate 27 into engagement with the catch plate 31.

Fig. 2 shows the handle 25 and latch member 27 with the door 1 in the fully closed position.

To open the door 1 the lever 16 is pressed to release the outer handle 7, pins 21,21 being retracted. Handle 7 is swung open to slide the plates 11 away from the bolt heads, the door is thus held closed only by the latch member 27..Handle 25 and latch member 27 form an over-centre lock or toggle mechanism.

The handle 25 is urged to its closed position as seen in Fig. 2 by the resilience of the '0' ring 34 tending to open the door, the couple formed between the pivot axes 26, 28 causing the latch member 27 to urge the handle 25 against the door 1. In another arrangement the couple may be provided by a spring or the like.

As the handle 25 is swung out from the door the pivot 28 swings about the pivot 26, to go over centre, to allow the door to open slightly. The spring 33 keeps the tongue 30 in engagement with the catch 31. If the door does not spring away from the flange 2, then the tongue 30 will be urged against the stop 32, allowing the handle 25 and latch member 27 to be used as a lever to lever the door open a few millimetres.

To release the tongue 30 from the catch plate 31, by urging the latch member 27 against the spring 33, the handle 25 has a step 35 which engages against a wall 36 on the latch member 27 as the handle 25 is swung through approximately 90 degrees, the latch member being caused to pivot about axis 26.

The outer handle covers the inner handle, 1 atch 16 extending through a hole in the inner handle 25, and triggers a microswitch as it is closed to indicate that the door is fully closed and locked, to allow activation of the autoclave.

In the embodiment illustrated in Fig 3, four slide plates 11 are provided and two latch members 27.

Various modifications will be apparent to those skilled in the art. For example, the slide plates 11 may be provided with dogs which project through slots in the door 1 and engage in recesses provided in the flange 2 as the slide plates 11 are slid home.

Claims (14)

1. A door lock for an autoclave, comprising first locking means for holding the door closed against an internal presure and second locking means for holding the door closed as said first locking means is released, wherein a handle for operating the first locking means overlays a handle for operating the second locking means.

2. A door lock as claimed in claim 1, wherein at least one of the handles comprises a lever.

3. A door lock as claimed in claim 2, wherein the handle of the first locking means substantially covers the handle of the second locking means.

4. A lock for a door, comprising a plurality of engagement means provided adjacent an opening of a chamber to be closed by the door, slide plate means slidably mounted on the door and adapted for form-locking connection with the engagement means, and a handle pivotably mounted on the door, the handle being operatively connected to the slide plate means so that when the door is closed the handle is pivotable between closed and open positions to slide the plate means into and out of form-locking connection with the engagement means respectively to prevent and allow opening of the door.

5. A lock as claimed in claim 4, wherein a latch is pivotably mounted on the handle to engage with a catch plate provided on the door when the handle is in the closed position, and a pin member is provided to hold the latch in engagement with the catch plate to prevent movement of the handle to the open position whilst temperature or pressure inside the chamber exceeds a predetermined limit.

6. A lock as claimed in claim 4 or 5, further comprising a second handle mounted on the door to pivot about a first axis, a latch member mounted on the second handle and pivotable about a second axis spaced form the first axis, a latch plate provided on the chamber and engageable by the latch member, the catch member and second handle forming an over-centre toggle mechanism whereby the second handle is movable from a first to a second position to partially open the door with the latch member remaining in engagement with the latch plate, and from the second to a third position to disengage the latch member from the catch plate.

7. A lock as claimed in claim 6, wherein the latch member is biassed against the catch plate.

8. A lock as claimed in claim 6 or 7, wherein stop means is provided on the container and the latch member is urged against the stop means as the handle is moved from the first to the second position, to lever open the door.

9. A lock as claimed in claim 6, 7 or 8, wherein the first said handle when in the closed position covers the second handle.

10. A lock as claimed in any one of claims 4 to 9, wherein means operatively connecting the first said handle and the slide plate means comprises a rack and pinion.

11. A lock as claimed in any one of claims 4 to 10, wherein a catch is provided to prevent movement of the first said handle to the closed position when the door is open, said catch being released as the door is closed.

12. A door lock for locking a chamber door, comprising a handle mounted on the door to pivot about a first axis, a latch member mounted on the handle to pivot about a second axis spaced from the first axis, a catch plate provided on the container and engaged by the latch member, the latch member and handle forming an over centre toggle mechanism whereby the handle is movable from a first to a second position to partially open the door with the latch member remaining in engagement with the catch plate, and from the second to a third position to disengage the latch member from the catch plate.

13. A door lock substantially as herein before described with reference to the accompanying drawings.

14. An autoclave having a chamber, a door and a door lock as defined in any one of the preceding claims.