Patent Description:
Railway vehicles for public mass transport are equipped with facilities such as toilets to improve passengers' comfort. The space in a railway vehicle is often limited so that the facilities are configured so as to use the available space most efficiently. For that reason, toilet compartments are designed to have, at least partially, walls with a curved or arc-shaped (shape of circular segment) outer contour. To take most advantage of this outer contour of the walls, the door leaf of a curved sliding door used to close the toilet compartment has also a curved or arc-shape so that the door can be moved along a circular path following the curved contour of the toilet compartment.

Modern railway vehicles are often equipped with fully automatic doors which can be operated by pressing a button by which an opening and closing mechanism is actuated. While those automatic doors are very convenient, they require extra equipment such as an electrical motor or other suitable electromechanical components which not only contribute to the total weight of the railway vehicle but may be prone to failure and require additional maintenance.

Sliding doors with different closing mechanisms are known. For example, <CIT> and <CIT> describe a self-closing structure of an elevator landing door. <CIT> describes a door assembly of a toilet compartment for handicapped persons using electromechanical components. <CIT> describes an electromagnetic type landing door self-closing system. <CIT> discloses a double linkage sliding door device for a toilet compartment of a railway vehicle. <CIT> describes another self-closing mechanism for railway vehicles. <CIT> describes a cabin with a rotatable cabin door for a vehicle. <CIT> describes a self-closing door assembly for an elevator. <CIT> describes an automatically closing sliding door. <CIT> discloses a device for automatically opening and closing a cabin door. <CIT> discloses a closing sequence control device for a self-closing door. <CIT> discloses a self-closing device for a door or window. <CIT> is related to a door device of a toilet. <CIT> is related to a suspension type door device. <CIT> is related to a semiautomatic opening/closing sliding door and its semiautomatic opening/closing device.

However, these mechanisms are often complicated and not suited for the limited space available in a railway vehicle.

In view of the above, there is need for improvement.

The above problem is solved by a self-closing door assembly for a sliding door according to claim <NUM>, a toilet cabin for a railway vehicle according to claim <NUM>, and a self-closing door assembly kit according to claim <NUM>. Further embodiments, modifications, aspects and advantages are disclosed in the dependent claims and the following description.

According to an embodiment, which can be combined with any other embodiment described herein, a self-closing door assembly of a curved sliding door includes a curved sliding door movable along a predefined curved path between an open position and a closed position, and a closing mechanism. The closing mechanism includes a spring device to move the sliding door into the closed position; a connecting element having a first end connected to the spring device and a second end connected to the sliding door; a plurality of diverter elements arranged along the curved path of the sliding door for guiding the connecting element along the curved path; and a damping element in engagement with the connecting element to limit movement of the connecting element when the connecting element is pulled by the spring device for moving the sliding door into the closed position. The spring device is tensioned, through transmission by the connecting element, when the sliding door towards the open position.

The self-closing door assembly is composed of few reliable mechanical elements and allows retrofitting of existing manual curved sliding doors. A challenge for curved sliding doors moving along a predefined curved path is that the door leaf of the sliding door rotates about a vertical axis which is off-set to the door leaf. Thus, a simple push-pull mechanism would not be a suitable choice for curved sliding doors. The present invention overcomes these drawbacks by using a connecting element which connects the spring device with the sliding door. The diverter elements are arranged along the moving path of the curved sliding door and guide the connecting element so that the connecting element can follow the predefined curved path along which the sliding door moves. The connecting element can therefore always pull the sliding door tangentially along the predefined curved path maximising the force transmitted from the spring device on the sliding door when closing the sliding door.

As a connecting element and diverter elements are used, the directional operation of the spring device does not need to be aligned with any tangential direction of the predefined curved path. This provides more freedom for arranging the spring device. The connecting element is typically bendable so that, when it moves together with the door leaf, it is bent to follow the curved path.

The diverter elements of the plurality of diverter elements can be arranged separately along the curved path. Along the curved path, a diverter element of the plurality of diverter elements can be arranged distant to another diverter element of the plurality of diverter elements, in particular distant to each other diverter element of the plurality of diverter elements. According to an embodiment, all diverter elements are arranged spaced from each other. In an embodiment, along the path, a gap is arranged between a diverter element and another diverter element, particularly a consecutive diverter element of the plurality of diverter elements. A length of the gap along the direction of the curved path can be larger than an extension of a diverter element along the curved path. Particularly, the length of the gap can be larger than a diameter of the diverter element of the plurality of diverter elements. Along the curved path, the plurality of diverter elements can be arranged equally distributed.

When referring to a curved path and a curved sliding door, basically any shape of a curve is meant. The curved path and the curved sliding door are specifically arc-shaped (circularly arc-shaped), i.e. they correspond to a segment of a circle. In typical embodiments, the segment is not more than a <NUM>-degree circular arc.

The driving element for closing the sliding door is provided by the spring device which is tensioned when the sliding door is manually opened by user. As the sliding door advances into its open position by action of the user, the connecting element pulls on the spring device and tensions a spring arranged within the spring device. If the user does not actively keep the sliding door open or block the sliding door, or if the door is not blocked by other means, the energy stored in the spring device results in a retracting force pulling the sliding door back into its closed position. Thus, the spring device acts as a mechanical energy storage means which stores tension energy supplied to the spring device, particularly to a spring of the spring device, when the sliding door is manually opened. The stored tension energy is used to close the sliding door.

The damping element limits the movement of the door, particularly the maximum speed at which the sliding doors closes. This is for the users' comfort and safety. The damping element can limit the movement of the door with respect to the speed at which the sliding door can move, particularly the speed at which the sliding door opens and/or closes.

The damping element can be arranged and configured to restrict the speed at which the sliding door closes. The damping element can decelerate the closing of the sliding door. The damping element can be arranged and configured for a smooth closing of the sliding door. The damping element can be arranged and configured to limit the speed of the sliding door during the movement of the door from its open position to its closed position.

The damping element can limit the maximum speed at which the sliding doors opens. Preferably, a damping element with asymmetric action is used. For example, the damping element may damp the closing movement of the sliding door more than the opening movement to allow the user to open the door more quickly. The maximum speed at which the sliding door can be opened may also be limited for safety reasons. The damping element can be arranged and configured to restrict the speed at which the sliding door opens. The damping element can decelerate the opening of the sliding door. The damping element can be arranged and configured for a smooth opening of the sliding door. The damping element can be arranged and configured to limit the speed of the sliding door during the movement of the door from its closed position to its open position. According to an embodiment, the damping element can be arranged and configured to restrict the speed at which the sliding door opens less than the speed at which the sliding door closes.

The self-closing door assembly described herein is particularly suitable for manually operated doors, i.e. for non-automatic doors which are not driven, or not partly driven, by electromechanical drive units. Moreover, the self-closing door assembly is easy to install, allows great flexibility for adapting to local geometries and designs, and is a cost-efficient solution. Specifically, for opening of the sliding door, manual operation, i.e. manual moving of the door by a user or passenger, is needed. The closing of the sliding door occurs automatically in the sense that the spring device brings the sliding door back into its closed position. The sliding door can also be closed manually. The self-closing door assembly is therefore autonomous as it does not require supply of electrical energy. It is semi-automatic (as it closes the sliding door automatically but requires manual work to open it) and fully mechanical as the closing can occur by action of the closing mechanism without requiring any electromechanical component and supply of electrical energy.

In addition to that, the self-closing door assembly described herein is particularly of advantage for curved sliding doors such as arc-shaped doors as diverter elements are used to guide the connecting element virtually along any curved path.

The spring device may include a housing for accommodating a spring arranged within the housing. The housing may include fastening means for attaching the spring device to structural elements such as a ceiling or a wall.

According to an embodiment, which can be combined with any other embodiment described herein, the spring device includes a spiral spring (torsion spring) for winding up the connecting element, which may be bendable or flexible but inelastic. For example, the spring device may be a spring rope pulley. A spiral spring allows for a compact design of the spring device. Furthermore, the spring force can be easily adjusted by the number of windings of the spiral spring. For example, if the spiral spring is provided with a higher number of windings and is pretensioned, the spring force can be kept in a linear range of the spring regardless of whether the door is fully opened or closed. In fact, when using a higher number of windings, the spring force can be kept approximately constant over the operating range defined by the maximum opening range of the sliding door.

According to an embodiment, which can be combined with any other embodiment described herein, the spring device includes an outer tube accommodating a helical spring (helical tension spring - linear tension spring) which is expanded along a longitudinal extension of the outer tube when moving the sliding door towards the open position. Instead of a spiral spring that winds up the connecting element, a helical spring can be used which linearly expands when the sliding door is opened. The spring device may have an elongated shape such as a shape of a tube. Specifically, an outer tube can accommodate the helical spring so that the helical spring is protected and guided at its outer side. The helical spring expands within and along the longitudinal extension of the outer tube. The outer tube may be provided with the fastening means for attaching the spring device to structural elements such as the ceiling of a cabin.

According to an embodiment, which can be combined with any other embodiment described herein, the spring device further includes an inner guiding element arranged in and extending along the outer tube, wherein the helical spring is wound around the inner guiding element and between the inner guiding element and the outer tube. Inner and outer tube cooperate together for guiding the helical spring and to prevent the helical spring from disengaging or deforming when expanding or contracting. The inner and outer tubes may be arranged coaxially relative to each other.

According to an embodiment, which can be combined with any other embodiment described herein, the inner guiding element includes an inner tube for guiding the connecting member therein. The inner tube may have a longitudinal slit through which a forward end of the helical spring connected with the connecting element extends into an interior of the inner tube. The connecting element is drawn into the inner tube when the helical spring contracts. The connection between the forward end of the helical spring and the connecting element is established through the longitudinal slit. For example, a fastener may be provided at the forward end of the helical spring which establishes the connection with the connecting element. The fastener may be guided along the slit to facilitate linear movement of the forward end of the helical spring and the connecting element.

According to an embodiment, which can be combined with any other embodiment described herein, the connecting element is flexible and inelastic. For example, the connecting element may be an inelastic rope, a chain, a cable, or a belt. The connecting element is preferably not elastic so that the connecting element can immediately transmit the force exerted from the spring device, i.e. from the spring of the spring device, to the sliding door or, when the sliding door is manually opened, from the sliding door to the spring device. The connecting element is thus, unlike the spring device, not an energy storage means. The connecting element can also be described as being limp. The flexibility the connecting element is provided with allows the connecting element to follow the curved path defined by the diverter elements without requiring application of a force, or only of a marginal force, for bending the connecting element.

According to an embodiment, which can be combined with any other embodiment described herein, the damping element is a radial damper, particularly a radial damper with adjustable predefined damping force. The predefined damping force may define the maximum speed for the closing movement of the sliding door. The predefined damping force is adjustable to allow adaptation to different scenarios and door constructions. Furthermore, the damping force may need to be adjusted after some time of operation, such as at regular maintenance intervals.

According to an embodiment, which can be combined with any other embodiment described herein, the closing mechanism further includes a timer element adapted to keep the sliding door in the open position for a predetermined delay time and to release the sliding door after lapse of the predetermined delay time. Keeping the sliding door in its open position for a predetermined time provides more comfort for the user as he passes the door. There is no need for the user to manually keep the door open. This is of particular importance for elderly people or differently abled persons, for example a person needing a wheelchair.

According to an embodiment, which can be combined with any other embodiment described herein, the timer element is a mechanical timer, particularly a mechanical timer with adjustable delay time, preferably without electromechanical components.

According to an embodiment, which can be combined with any other embodiment described herein, the closing mechanism further comprises a safety element for stopping the sliding door from reaching the closed position. The safety element is particularly an end position stopper decelerating movement of the door. The safety element prevents trapping of fingers or other body parts by the closing door.

According to an embodiment, which can be combined with any other embodiment described herein, a toilet cabin for a railway vehicle is provided. The toilet cabin includes a bottom, a ceiling assembly, at least two sidewalls extending between the bottom and the ceiling assembly, and a self-closing door assembly according to any of the embodiments described herein. The spring device, the plurality of diverter elements and the damping element of the self-closing door assembly are attached to the ceiling assembly. The connecting element is attached to an upper end of the sliding door. The self-closing door assembly as described herein is particularly useful for toilet cabins of railway vehicles. However, the invention is not limited thereto and can also be applied to other cabins having a manually operated curved sliding door, for example for any cabin in a railway vehicle, in any other vehicle such as vessels, or in buildings.

According to an embodiment, which can be combined with any other embodiment described herein, the spring device, the plurality of diverter elements and the damping element of the self-closing door assembly are arranged in a common level plane extending parallel to the bottom of the cabin. Preferably, all elements of the self-closing assembly are attached or fastened on the ceiling of the cabin. The working operation of all moving and movable parts of the self-closing assembly are preferably within a common level plane.

According to an embodiment, which can be combined with any other embodiment described herein, the toilet cabin further includes a bottom guiding rail in engagement with a lower end of the sliding door to guide the sliding door at its lower end. This bottom guiding rail stabilizes the door leaf of the sliding door at its lower end. Alternatively or in addition to the bottom guiding rail, a top guiding rail may also be provided which is in engagement with an upper end of the sliding door.

According to an embodiment, which can be combined with any other embodiment described herein, a self-closing door assembly kit for a curved sliding door, which is movable along a predefined curved path between an open position and a closed position, is provided. The kit includes a spring device; a connecting element having a first end for connecting to the spring device and a second end for connecting to the sliding door; a plurality of diverter elements for arranging along the curved path of the sliding door for guiding the connecting element; and a damping element for engagement with the connecting element to limit movement of the connecting element. The self-closing door assembly kit can further optionally include a timer element adapted to keep the sliding door in the open position for a predetermined delay time and to release the sliding door after the elapsing of the predetermined delay time; and a safety element for stopping movement of the sliding door.

The assembly kit may be used to retrofit an existing manual sliding door, for example in railway vehicles.

The invention will now be described with reference to embodiments without limiting the scope as defined by the claims.

The appended drawings illustrate embodiments and serve in combination with the description for explaining the principles of the invention. Elements in the drawings are relative to each other and are not necessarily to scale unless otherwise stated.

<FIG> illustrates a toilet cabin <NUM> for a railway vehicle. The toilet cabin <NUM> includes a ceiling assembly <NUM>, at least two sidewalls 120a, 120b extending between the bottom <NUM> and the ceiling assembly <NUM>, and a curved sliding door <NUM>. A door opening <NUM> is arranged between and defined by opposite side edges of the at least two sidewalls <NUM>. At least one of the sidewalls 120a can be at least partially curved to form, together with the curved sliding door <NUM>, a partially curved outer shape of the toilet cabin. The toilet cabin <NUM> may include a substantially flat sidewall 120b, such as shown to the right of the door opening <NUM>, and an at least partially curved sidewall 120a, such as shown to the left of the door opening. The sliding door <NUM> closes the door opening <NUM> when moving towards the substantially flat sidewall 120b. A closing mechanism for the sliding door <NUM> is attached above the top side of the ceiling assembly <NUM>.

When opening the sliding door <NUM>, the door leaf of the sliding door <NUM> moves behind the partially curved sidewall 120a at the inner side of the curved sidewall <NUM>.

The toilet cabin <NUM> may be a self-supporting toilet cabin where the bottom <NUM>, the at least two sidewalls 120a, 120b, and the ceiling assembly <NUM> form a self-supporting structure. Alternatively, the bottom <NUM> may be formed by the inner floor of the railway vehicle and the at least two sidewalls 120a, 120b are fixed to the floor or to a supporting structure attached to the floor.

The specific arrangement of the toilet cabin <NUM> is not limited as the closing mechanism can be used for any type of toilet cabins <NUM>.

Embodiments of the self-closing door assembly comprising a curved sliding door <NUM> and a closing mechanism are described with reference to <FIG>, <FIG>, <FIG> and <FIG>. <FIG> shows a spring device with a spiral spring which may be used in the embodiment shown in <FIG> and <FIG>. <FIG> shows a spring device with a helical spring which may be used in the embodiment shown in <FIG> and <FIG>.

Turning first to <FIG> and <FIG>, a self-closing door assembly having a spring device <NUM> with a spiral spring for winding up a connecting element <NUM> according to an embodiment is described. In the following, the connecting element <NUM> is referred to as flexible connecting element as it is preferably flexible and inelastic. The sliding door <NUM> is shown in a closed position in <FIG> and in an open position in <FIG>.

The flexible connecting element <NUM> connects a leading edge <NUM> of the door leaf of the sliding door <NUM> with the spiral spring of the spring device <NUM>. The spiral spring <NUM>, see <FIG>, is accommodated within a housing <NUM> of the spring device <NUM>. The spring device <NUM> may be a spring rope pulley. The spring device <NUM> may further include a roll <NUM> that is connected with the spiral spring <NUM> which is arranged within the roll <NUM>. The flexible connecting element <NUM> is wound up on the outer circumference of the roll <NUM>. The flexible connecting element <NUM> may be a rope which is a simple and cost-efficient, yet a reliable, flexible but inelastic connecting element. Another preferred embodiment includes a cable. Further embodiments include a chain or a belt. The spiral spring <NUM> engages with the roll to drive the roll <NUM> for winding up the flexible connecting element <NUM>. On the other hand, when the sliding door <NUM> is manually opened by a passenger the flexible connecting element <NUM> is unwound by the action of the sliding door <NUM> moving towards its open position and causes the roll <NUM> to tension the spiral spring <NUM>.

While the present embodiments show that the flexible connecting elements <NUM> is connected to the leading edge <NUM> of the door leaf, the flexible connecting element <NUM> can also be connected with other portions of the door leaf such as at a position spaced by a given distance from the leading edge <NUM>.

Turning back to <FIG> and <FIG>, the flexible connecting element <NUM> engages with a damping element <NUM> which is arranged between the spring device <NUM> and the leading edge <NUM> of the closed sliding door <NUM>. The damping element <NUM> may also divert the flexible connecting element <NUM> to increase engagement between the flexible connecting element <NUM> and the damping element <NUM>.

The damping element <NUM> may be a radial damper that damps rotation of a roll or wheel which engages with the flexible connecting element <NUM>. If a chain or a belt is used as the flexible connecting element <NUM>, the roll of the damping element <NUM> may include teeth to improve engagement with the chain. A belt may also be used in combination with a cylindrical roll. Alternatively, the flexible connecting element <NUM> may be wound around the roll which also increases the engagement.

If the damping element <NUM> does not divert the flexible connecting element <NUM>, additional auxiliary pulleys can be used to locally divert the flexible connecting element <NUM> partially around the roll of the damping element <NUM>. For example, by means of cooperation of one or two auxiliary pulleys with the roll of the damping element <NUM>, the flexible connecting element <NUM> may be locally forced to follow an S-shaped or U-shaped path to increase engagement with the roll or wheel of the damping element <NUM>.

The damping force of the damping element <NUM> may be adjustable.

According to an embodiment, the damping element <NUM> may not even decelerate movement of the sliding door <NUM> but also actively draws the sliding door <NUM> into its final closed position.

As illustrated in <FIG> and <FIG>, a plurality of diverter elements <NUM>, 240a are arranged approximately along the curved path of the sliding door <NUM>. For example, five diverter elements <NUM>, 240a can be used without being limited thereto. Typically, at least three, particularly at least four diverter elements <NUM>, 240a are used.

The diverter elements <NUM>, 240a cooperate with and guides the flexible connecting element <NUM> so that the flexible connecting element <NUM> approximately follows the course of the sliding door <NUM>. This results in a mutual action between the sliding door <NUM> and the flexible connecting element <NUM> to be always tangential relative to the predefined curved path of the sliding door <NUM>. Forces acting radially on the sliding door <NUM> are thus avoided which prevents impairing movement of the sliding door <NUM>.

The sliding door <NUM> is shown in its closed position in <FIG>. To prevent the passenger's finger becoming trapped when the sliding door <NUM> closes, a safety element <NUM> is provided which damps movement of the sliding door <NUM> immediately before the sliding door <NUM> is fully closed. The safety element <NUM> may be an end position damper which may be fastened to that sidewall 120b towards which the sliding door <NUM> moves when closing. For example, the safety element <NUM> may be a hydraulic element including a piston that displaces oil in a cylinder and thus absorbs the kinetic energy of the moving sliding door <NUM>. The safety element <NUM> may have different damping characteristics such as uniform damping over the whole stroke of the piston or progressive characteristic with initial gentle start and progressive damping as the piston is moving. To return the piston into its initial position when the sliding door <NUM> is opened, the safety element <NUM> may include an internal spring which pushes the piston back. The hydraulic damping also provides for a controlled and reliably, particularly gently, damping irrespective of the size and weight of the sliding door <NUM>. Furthermore, impact on the movement of the sliding door <NUM> by vehicle movement can be absorbed by the safety element <NUM>.

Turing to <FIG> the sliding door <NUM> is shown in its open position with the flexible connecting element <NUM> pulled out from the spring device <NUM> to is maximum extension. As shown in <FIG>, the flexible connecting element <NUM> follows the predefined curved path of the sliding door <NUM> because of the diverter elements <NUM>, 240a arranged along the curved path.

When the sliding door <NUM> is moved towards its open position, the spring device <NUM> becomes increasingly tensioned. It is not required to always open the sliding door <NUM> to its maximum open position as the spring device <NUM> will be sufficiently tensioned even when the sliding door <NUM> is opened to any intermediate position. Preferably, the spring device <NUM> is already tensioned when the sliding door <NUM> is in its closed position. The "pre-tension" of the spring device <NUM> ensures that the sliding door <NUM> can reliably be closed and is kept closed even when the railway vehicle moves.

When the passenger opens the sliding door <NUM>, it comes in engagement with a timer element <NUM> which keeps the sliding door <NUM> open for a predetermined delay time. The predetermined delay time can be adjusted and may be about few seconds. After lapse of the predetermined delay time the timer element <NUM> releases the sliding door <NUM> which then closes by action of the spring device <NUM>. The timer element <NUM> is preferably a mechanical timer, particularly a mechanical timer with adjustable delay time, preferably without electromechanical components. For example, a lever of the timer element <NUM> may be in engagement with a counterpart attached to the sliding door <NUM>. The lever is movable and is pushed into engagement when the sliding door <NUM> is opened and thus blocks the counterpart. Releasing the counterpart by the lever being in engagement with the counterpart is hydraulically damped using an oil piston. The hydraulic damping can be adjusted, for example by controlling the opening size of a value that limits flow of a hydraulic fluid within a piston that acts on the lever.

With reference to <FIG> and <FIG> another embodiment of the self-closing door assembly is described. Unlike the embodiment of <FIG> and <FIG>, the embodiment of <FIG> and <FIG> employs a spring device <NUM> with a helical spring that is expanded, and which contracts, along a straight line. <FIG> illustrates a spring device <NUM> which may be used in combination with the embodiment of <FIG> and <FIG>. The remaining parts may be the same as in the embodiment shown in <FIG> and <FIG>.

The spring device <NUM> may include an outer tube <NUM>, an inner tube <NUM>, and a helical spring <NUM> which is wound around the inner tube <NUM>. The outer tube <NUM> and the inner tube <NUM> define together a space between the inner tube <NUM> and the outer tube <NUM> along which the helical spring <NUM> can be linearly expanded and contracted. Thus, inner tube <NUM> and outer tube <NUM> guides movement of the helical spring <NUM>.

The outer tube <NUM> may be provided with fastening means to attach the spring device <NUM> at the ceiling of the toilet cabin <NUM>.

A forward end of the helical spring <NUM> is connected with the flexible connecting element <NUM>. For example, a fastener <NUM> connects the forward end of the helical spring <NUM> with the flexible connecting element <NUM>.

For guiding the flexible connecting element <NUM> within the spring device <NUM>, the inner tube <NUM> may be provided with a slit <NUM> extending along the longitudinal extension of the inner tube <NUM>. The fastener <NUM> extends through the slit <NUM>. When the helical spring <NUM> contracts, the fastener <NUM> draws the flexible connecting element <NUM> into the inner tube <NUM> so that the flexible connecting element <NUM> and the helical spring <NUM> do not accommodate the same space.

Similar to <FIG> and <FIG>, <FIG> shows the sliding door <NUM> in its closed position while <FIG> shows the sliding door <NUM> in its open position. The opening and closing sequence are the same so that a repetition of the detailed explanation is omitted.

In all embodiments shown herein, the spring device <NUM>, <NUM> can be arranged at virtually any position when additional diverter elements are used to divert the flexible connecting element <NUM> towards the spring device <NUM>, <NUM>. A diverter element 240a may be arranged where the leading edge <NUM> of the sliding door <NUM> comes to rest when the sliding door <NUM> is in the closed position. In the embodiments shown in <FIG>, <FIG>, <FIG> and <FIG>, no additional diverter element is arranged between the diverter element 240a and the respective spring device <NUM>, <NUM>. However, an additional diverter element may be positioned such that the spring device <NUM>, <NUM> can be arranged at a location other than that shown in the drawings.

The self-closing door assembly kit can be used with advantage to retrofit manual curved sliding doors, not only in railway vehicles but also in buildings. Only few components are needed which can be arranged in a flexible manner to take account of the specific design and the available installation space.

Claim 1:
Self-closing door assembly of a curved sliding door, comprising:
a curved sliding door (<NUM>) movable along a predefined curved path between an open position and a closed position; and
a closing mechanism comprising:
a spring device (<NUM>, <NUM>) to move the sliding door (<NUM>) into the closed position;
a connecting element (<NUM>) having a first end connected to the spring device (<NUM>) and a second end connected to the sliding door (<NUM>), the spring device (<NUM>, <NUM>) being tensioned when moving the sliding door (<NUM>) towards the open position;
a plurality of diverter elements (<NUM>, 240a) arranged along the curved path of the sliding door (<NUM>) for guiding the connecting element (<NUM>) along the curved path; and
a damping element (<NUM>) in engagement with the connecting element (<NUM>) to limit movement of the connecting element (<NUM>) when the connecting element (<NUM>) is pulled by the spring device (<NUM>, <NUM>) for moving the sliding door (<NUM>) into the closed position.