Fire protection is a very important issue in all compartments, in particular in compartments where people cannot escape from a fire, such as in transport compartments. For example, in train compartments fireproof walls are required to protect the passengers or the driver of the train from a fire in another compartment. Such fireproof walls are not only required to be fire-resistant; they also have to prevent leakage of smoke into the other compartments. Smoke poses a risk because it can spread the fire to the other compartments but, more importantly, smoke is dangerous because inhalation can lead to poisoning, suffocation and death. It is particularly difficult to make walls fireproof at the wall edges where a sliding door is provided.

In EP 0534932 B1, a fireproof wall is described, wherein the gaps between the various structural components, in particular also between the sliding door and bushing at the receiving edge of the wall, are provided with an intumescent sealing material. An intumescent material is a material that expands when exposed to a temperature above the expansion temperature of the material.

The problem of the described sliding door assembly is it does not sufficiently protect against leakage of smoke on exposure to a fire. It was found that, on exposure to fire, the entire fire protection wall significantly deforms, mainly by bulging out towards the fire.

This deformation creates and enlarges gaps making the provided sealing ineffective,

especially in those places where connections are made between different materials, in particular between the sliding door and the wall. There is, therefore, a need for an improved fireproof sliding door assembly for a fire protection wall.

According to the invention, there is provided a fireproof sliding door assembly for a fire protection wall, comprising a wall part and a sliding door wherein the wall part has a receiving edge for receiving the sliding door in an open position of the door, wherein the door is positioned at a front side of the wall part where fire is expected, overlapping the receiving edge of the wall part forming a gap, which gap has, in a closed-door position, a sealing along the length of the gap which on exposure to fire seals the gap and which door comprises a door locking element that, at least in a closed-door position, locks to a wall part locking element on the wall part limiting the gap width to a maximum width.

It was found that the fire protection wall comprising the sliding door assembly according to the invention provides better protection against leakage of smoke through the gaps between the sliding door and the wall part. "Better protection"means protection at higher temperature and/or longer exposure times.

The physical interlocking of the door locking element and the wall locking element ensures that, during deformation of the fire protection wall on exposure to fire at the front side, the wall part coherently deforms with the deformation of the sliding door, such that the interlocking door and wall locking elements form a rigid block fixing the gap to a width less than or equal to the maximum width. The maximum gap width can be chosen in view of the particular sealing used and in general is below the maximum width of the sealing. The sealing can be intumescent material or elastic material, preferably compressible elastic material. The maximum width of the sealing then is, respectively, the maximum expansion width of the intumescent sealing when exposed to elevated temperatures or, in the case of compressible elastic sealing, the maximum width in an uncompressed state.

The interlocking of the door locking element and the wall locking element must take place at least in the closed-door position. Preferably, the interlocking takes place only in the closed-door position, but alternative embodiments are conceivable where the sliding door is interlocked with the wall element also in the open position of the door even though, evidently, in case of a fire the door must always be closed.

The interlocking of the door locking element and the wall locking element must be sufficiently strong to be able to coherently deform the wall part. In order to make the coherent deformation easier it is preferred that in the fireproof sliding door according to the invention at least a portion of the wall part near the receiving edge has a stiffness sufficiently low to follow deformation of the sliding door on exposure to fire at the front side.

The wall part can be a complete wall having an opening in which the sliding door assembly is provided or just part of a wall or a frame that is to be mounted in the opening of a wall. In the latter case, the wall part must have sufficient length to be able to accommodate the deformation of the sliding door and the wall on exposure to heat.

In a preferred embodiment of the invention, the wall part is a hollow double wall part further comprising a front wall part positioned at the front side of the door and overlapping with the door forming a front gap between the door and the front wall part. The advantage of a double wall is that the components of the fireproof sliding door assembly are protected from the fire at the front side by the front wall part making it easier to secure the fire resistance of the assembly. Preferably, the back wall part and the front wall part are made of fire-resistant material. Preferably also, a sealing is provided for closing the front gap at least in a closed-door position.

"At least in a closed-door position"means that the sealing is present in the front gap when the sliding door is in a closed-door position. The sealing can be provided in the gap on the wall part or the sealing can be provided on the door edge, or near the door edge, engaging the wall part only in closed-door position.

The embodiments hereabove described, the sliding door assembly and the fire protection wall comprising the sliding door assembly are construed to protect against exposure to a fire on one side only. In a preferred embodiment of the fireproof sliding door assembly according to the invention, the door has a further second door locking element that, at least in a closed-door position, locks to a second wall part locking element at the front wall part limiting the front gap width to a maximum gap width. The advantage of this embodiment is that it protects against fire on both sides of the sliding door assembly.

Preferably, the sealing comprises two different materials, the first sealing material sealing the gap in a first temperature range, and the second sealing material sealing the gap in a second higher temperature range and wherein the second temperature range partly overlaps the first temperature range. The advantage of this is that the gap is protected against leakage of smoke over a wide temperature range from room temperature up to the high temperature of a full-blown fire.

A suitable example thereof is a sealing comprising intumescent material and, adjacent thereto, an elastic material.

In the low-temperature range, the gap is sufficiently sealed and protected by the elastic material and, if the fire is not too destructive, the sliding door assembly does not need to be replaced. In case of a severe fire involving temperatures where the elastic material will deform, the intumescent material takes over the function of sealing material by expanding and filling the gap.

The intumescent material starts to expand at an elevated temperature but below the heat deformation temperature of the elastic material.

The intumescent material is preferably positioned near the front side where fire is expected and adjacent thereto an elastic material at a position further removed from the front side. In this way, the intumescent material reaches a higher temperature earlier than

the elastic material, which ensures that it starts to expand before the elastic material is deformed by the heat and, as such, also protects the elastic material from further deformation by the heat.

Alternatively, a heat bridge is provided to the intumescent material to ensure that on exposure to fire the intumescent material reaches the expansion temperature before the heat deformation temperature of the elastic material.

A suitable material for the elastic material is a heat-resistant elastic material, preferably a silicon rubber elastic material.

In the sliding door assembly, one or preferably both gaps can suitably be sealed, in closed position only, by a, preferably elastic, strip connected to a side face of the door near the receiving end of the wall part, wherein the strip extends beyond the edge of the side face of the door contacting the wall part and covering and sealing the gap. This sealing is preferably used only in a double wall construction and with intumescent material in the gap on both sides of the door nearer to the expected fire.

The door locking element can, for example, be a hook, a plurality of hooks, or an elongate angle profile having one side attached to the door and the other side extending from the door to engage the wall part locking element. The wall part locking element can, for example, be a simple ridge provided on the wall part, behind which the hook or the angle profile is hooked. Interlocking can also be achieved by providing a rail or plurality of rails parallel to the sliding direction of the door, in which an anchor attached to the door is guided.

In the fireproof sliding door assembly according to the invention, preferably also the closing edge opposite the receiving edge is protected against fire. Preferably, the wall part has a closing edge opposite to the receiving edge having a side face provided with a recess for engaging the sliding door in closed-door position, which recess has at the front

side or on both sides of the door a blocking surface for blocking heat deformation movement of the door and wherein a gap between said surface and the door comprises along the length of the gap, at least in a closed-door position, a sealing which on exposure to fire seals the gap against leakage of smoke.

Similar to the receiving edge of the wall part, preferably also at least a portion of the wall part at the closing edge has a stiffness sufficiently low to follow deformation of the fire protection wall on exposure to fire at the front side.

Although the fireproof sliding door assembly according to the invention relates specifically to the fire and smoke protection of the gaps at the receiving and the closing edges of the wall, it is clear that the openings and connections on other edges of the wall must be made fire and smoke proof as well. The sliding door is provided with sliding guidance elements, normally horizontally, at the top and bottom of the sliding door.

Preferably also, the gaps between these sliding guidance elements and the sliding door are provided with a sealing, preferably a combination of intumescent and elastic material as described above, to seal the gap in case of a fire. Preferably, all materials used in manufacturing the fire protection wall are fire-resistant.

The invention also relates to a fireproof wall comprising a fireproof sliding door assembly according to the invention and to a rail vehicle comprising such a fireproof wall.

The fire protection wall of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a sliding door assembly showing a sliding door in closed position at the receiving end of the wall part, interlocking with the back wall part.

Figure 2 is a cross-sectional view as in Fig. 1 but showing the interlocking on both the front and the back wall part.

Figure 3 is a cross sectional view of a sliding door assembly showing the sliding door in closed position at the closing end of the wall part.

Detailed Description of the Drawings Figure 1 shows a cross-sectional view showing a sliding door (1) in closed-door position, partly overlapping the receiving end (9) of the wall part (10) forming a gap (11), which gap (11) has a sealing along the length of the gap, which sealing is formed by a strip of intumescent material (4) and an elastic material (5). Attached to the door (1) at a side face engaging the receiving end of the wall part is a door-locking element (2) locking to a wall part locking element (3) on the wall part, limiting the gap width of gap (11) to a maximum width. The wall part locking element (3) is a simple ridge attached to the wall part (10), which allows the hook to move in one direction but not in the other direction, hence limiting the gap width at the back side to a maximum gap width. The wall is provided with a front wall part (13) to make a hollow double wall, creating a front gap (12), which is also sealed by an intumescent strip and elastic strip (5). A frame (6) is provided to abut the elastic sealing strip (5). The embodiment shown in Figure 1 provides protection only from one side (indicated by an X). Figure 1 further shows provisions (8) to seal the connections between separate parts. Such connections, in case of a fire, tend to open and leak smoke. The sealing means (8) provide a sealing to prevent passage of smoke through the opened connections.

Figure 2 shows a cross-sectional view similar to Figure 1, with the different that, in Figure 2, the door is provided with a second door locking element, engaging and interlocking with a second wall part locking element (14) at a front wall part. In this particular embodiment, the first and second door locking elements are simply combined into one part and extending on both sides of the door.

Figure 3 shows a cross-sectional view of a door assembly showing the sliding door (1) in closed position at the closing end (15) of the wall part. The side face of the closing edge is provided with a recess (16) for engaging the sliding door. In the recess, there is provided at the front side of the sliding door (indicated by an X) a blocking surface (17) for blocking heat deformation movement of the sliding door. At the closing edge, fire protection is afforded at low temperature by the contact between the closing edge of the wall part and an elastic material (18) provided at the side face of the sliding door. For protection at high temperature, there is provided in the gap between the blocking surface at the front and the back side of the sliding door an intumescent layer (4) along the length of the gap.