The present invention relates to a water closet (WC) having an odour extraction unit.

WCs having a flushing water connection are known for a long time and are common. The flushing water flows via the flushing water connection through a flushing channel and through a flushing water outlet into a so called WC bowl for flushing the latter. Then, the used flushing water flows together with the contents of the WC bowl flushed away into a drain line, wherein a so-called siphon is usually provided as an odour trap.

Further, it is basically known to provide such a WC with an odour extraction unit which sucks in air from the WC bowl. Therein, suck-off openings above, but close to, the WC bowl are known as well as suck-off openings within the actual WC bowl. In particular, it is known to use the flushing channel of the flushing water for sucking of the air and to connect the odour extraction unit to the flushing channel. Then, the odour extraction unit can, as far as the flushing channel is not used for flushing, suck- in air and odours therewith from the WC bowl through the flushing water outlet via the suck-off connection, namely the connection of the odour extraction unit to the flushing channel. The air sucked in can for instance be supplied to a filter, for instance an activated carbon filter, and can then be led to the room again. It can also be vented outside or be supplied to an exhausted air unit.

The technical problem this invention is to solve is to provide a WC having an odour extraction unit which is connected in a simple way to the flushing channel and protected against an entry of flushing water and, therein, allows an advantageous course of the flushing water channel.

The problem is solved by arranging the suck-off connection at a location of the flushing channel which has, due to dynamic flow effects occurring in an ideal fluid, a reduced or vanishing static pressure. This shall not imply an ideal, frictionless flow behaviour of the water, but shall only mean that the concept of the invention results in a reduced pressure at the connection location of the suck-off connection independently of frictional losses in the water flow; thus, the inventive concept does necessitate undesirably large frictional losses caused by the shape of the flushing channel.

Therein, there are two possibilities, namely a deflection of the flow by a bend and the arrangement of the suck-off connection at the inside of the bend on the one hand. Due to the centrifugal force of the water, the static pressure is reduced on the inside of the bend, namely on the suction side, and is increased on the outside of the bend, the pressure side. The other possibility is to provide a narrowing of the cross section of flow to accelerate the flow and respectively reduce the static pressure, which can also be illustrated by the Bernoulli equation. In both cases, it is desirable to design the suck-off connection in such a way that the water has a minor or no dynamic pressure in the suck-off connection. The two cases do not exclude each other, but are preferably combined.

In the first case, the suck-off connection is preferably arranged at the "innermost" position of the flushing channel (of the perimeter thereof). However, this does not apply necessarily. The suck-off connection does not have to be provided at or symmetrically to the innermost position, but can also be arranged asymmetrically. Preferably, the cross section of the suck-off connection is provided on the inside in so far as lines of the flushing channel wall can be defined, which lie on the perimeter of the flushing channel as a border between the outside and the inside of the (local) plane of the bend. With this in mind, the larger part of the cross section of the suck-off connection shall be located on the inside.

As regards the second case, the narrowing occurs, in the most general sense, locally and the term does not relate to a comparison with the flushing channel as a whole. However, preferably, the cross-section of flow is, for at least 10 cm downstream of said suck-off connection and preferably up to the flushing water outlet, constantly larger than in the narrowing. Preferably, the same applies, alternatively or additionally, for the upstream direction, namely preferably up to a flushing water connection. Therein, the flushing water connection of the WC body is meant, not further flushing water supply parts for instance inside an installation wall. Openings "provided in parallel", for instance openings pointing downwards along a ring-shaped flushing channel of a classical WC, shall therein be considered with the sum of their cross sections of flow.

In comparison to a cross-section at a location at the flushing water connection upstream of the narrowing, the cross section of the narrowing should have a quantitative ratio of 1 :1 ,1 to 1 :2, wherein, respectively in this order increasingly preferred, lower limits of 1 :1 ,2; 1 :1 ,3 and 1 :1 ,4 and upper limits of 1 :1 ,9; 1 :1 ,8; 1 :1 ,7 and 1 :1,6 are further preferred. Further, the minimal cross section of flow of the suck-off connection is preferably equal to or smaller than the cross section of flow of the narrowing (within the flushing channel itself), preferably in a ratio between 1 :1 and 1 :3, wherein lower limits of 1 ,2; 1 ,4; 1 ,6; 1 ,8 and, for the second number, upper limits of 2,8; 2,6; 2,4; 2,2 are in this order increasingly preferred. The exemplary embodiment illustrates these ratios with a ratio of the cross sections of 1 :2.

Further, the bend of the flushing channel in the region of the suck-off connection can be preferably also provided within certain quantitative limits, namely, considering a mean value over an angular range of 40°, between the one-fold and the ten-fold typical inner radius (square root out of (cross sectional area divided by π)) of the flushing channel there. Therein, the two-fold and the three-fold are further preferred lower limits, and the eight-fold, six-fold and four-an-a-half-fold are further preferred upper limits.

A further embodiment of the invention relates to a water separator. This is a container or at least a widening of the cross section by a factor of 2 on the suck-off side of the suck-off connection (and relatively to the narrowest location of the latter), namely outside the flushing-channel, but preferably close thereto. The odour extraction unit can be connected to this water separator, preferably in an upper region of the water separator. Therewith, water which entered through the suck-off connection despite the measures of this invention can be trapped in the lower region on the bottom of the water separator and does not or only in a minimal amount enter into the connection of the odour extraction unit. Thus, the water separator works due to the gravity of the water. The water separated therein can be collected and drained elsewhere. In a preferred embodiment, it is led back to the flushing channel by a slope of the bottom of the water separator.

Preferably, the odour extraction unit is connected in an upper region of the water separator, particularly preferred in an upper region oriented opposite the direction flow of the flushing water. This means that remaining flushing water having entered with the flushing water flow is flown with a certain flow direction in the flushing channel and therefrom into the water separator; thus, it preferably hits a respective side of the water separator. The preferred position for the connection of the odour extraction unit is opposite thereto, as illustrated by the exemplary embodiment.

In combination with a washlet, namely a shower unit of the WC, the water separator can be further used for connecting a water overflow of a shower tank of the shower unit thereto, preferably in an upper region of the water separator. The shower unit is not necessarily integrated into the WC; it can also be an attachment or an upgraded or a structurally separated part in general.

The measures according to the invention can, individually and particularly when combined, reduce or hinder the entry of flushing water into the odour extraction unit, because only little or no water passes through the suck-off connection due to the flow effects mentioned. This is an elegant and simple solution. It can further prevent problems in terms of the technical effort, the volume required for components, the cost, the level and intensity of maintenance and so on, which can occur when preventing the entry of flushing water into an odour extraction unit by conventional valves or flaps. Preferably, the invention is applied to provide a supply line of the odour extraction unit from the suck-off connection on including the latter without such flaps or valves, mainly to keep the supply line free.

It has been mentioned already that making use of the flow effects of an ideal fluid being independent of inner friction, allows an advantageous arrangement of the suck- off connection in terms of flow and pressure, wherein the overall flow resistance can be kept small at the same time. This is of a particular interest in case of a gravimetric flow, namely a flow being driven only by the gravity of the flushing water without a flushing water supply pump internally the WC. A commonly known example is a WC having a cistern which is located higher than the WC bowl. In this context, a design of the flushing channel, being advantageous in terms of flow, is of a particular interest when a reduced amount of flushing water shall be used for ecological or economical reasons. Therein, a concealed cistern is preferred, particularly a concealed cistern mounted in a mounting frame inside the wall.

By assuring an effective flow of the flushing water through the flushing channel, not only the flushing effect of a comparably small amount of flushing water in the bowl is improved, but also the kinetic energy of the flushing water when passing through the drain, namely in particular through a siphon, is increased. Insofar, the invention can advantageously be applied in case of a WC having a static siphon. This relates to a siphon which works without an additional mechanical actuation by for instance a flap or the like. Further, the invention is advantageous in case of a WC having, for a reduction of the flushing water required, also no separate exit nozzle for the flushing water slightly above the siphon. Such exit nozzles are known as such and are applied for accelerating the flushing water in the region of the siphon. In combination with a comparably fast flushing water flow, they can advantageously be omitted.

Finally, the kinetic energy of the flushing water can be used or even increased by letting the flushing water enter the WC bowl with as little disruption as possible and by letting it flow into the WC bowl with a preponderant tangential velocity component to reach the siphon in a manner rotating through the bowl.

In the following, the invention is further explained by means of an exemplary embodiment, wherein the individual features can also be of relevance for the invention in a different combination.

Fig. 1 shows a top view on a WC according to the invention.

Fig. 2 basically corresponds to Fig. 1 , but shows a top view partly in section, wherein the horizontal sectional plane is located slightly below the upper edge of the WC.

Figs. 3A, 3B and 3C show a perspective view, a top view and a section along a

C-C plane of a part of the flushing channel shown in Fig.

2. Fig. 4 shows a perspective view of a rear side of a part of the

WC as shown in Figs. 1 and 2.

Fig. 1 shows a top view of a WC according to an invention. The reference numeral 1 refers to a central WC bowl, the reference numeral 2 to a toilet seat. The reference numeral 3 relates to a conventional flushing water drain which is connected to the water level within the WC bowl 1 via a siphon; the reference numeral 4 relates to a flushing water connection. To this extent, the WC shown in Fig. 1 is conventional (apart from the design of the flushing water exit in the bowl 1 , explained below).

From the flushing water connection 4, a bended pipe 5 leads to the right upper side of the bowl 1 in Fig. 1. Fig. 2 shows a sectional view through a plane located slightly below and particularly shows the pipe 5 more in detail, which is referred to as flushing channel part here. It leads into a flushing water nozzle 6 which functions as a flushing water outlet at the right side of the flushing bowl 1 in Figs. 1 and 2. The nozzle 6 leads the flushing water with a tangential velocity direction into the WC bowl 1 , in an upper region thereof, so that a rotating and, particularly in comparison to a conventional flushing rim having a plurality of small outlet openings, fast flushing water flow in the WC bowl 1 results. The flushing nozzle 6 as the flushing water outlet and the pipe 5 together are the flushing channel.

Fig. 2 further illustrates two through-passages in a rearward region of the WC bowl 1 , formed into the ceramic material and provided for a shower arm (centrical) and a hot air blower arm at the left thereof. A washlet is shown.

The flushing channel part 5 is shown in Figs. 3A, 3B and 3C in further detail, wherein the dot-dashed line C-C in Fig. 3B illustrates the sectional plane of the sectional view in Fig. 3C. It can be seen that the cross-section of the flushing channel part 5 reduces from a larger circular cross-section subsequent to the flushing water connection 4 at a step 7 to a circular cross-section reduced by a factor of 1 ,5 (referring to the area). This reduced cross-section is kept in the region downstream of the step 7, which region is rather strongly bended. This region is referred to as narrowing 8 here. Upstream of the step, the cross-section of flow is about 15 cm ² , and downstream thereof, within the narrowing 8, it is about 10 cm ² (wherein the distance between the sectional plane C-C in Fig. 3B and the part of the flushing channel part 5 corresponding the step 7 is, with respect to the direction of flow, about 4 cm). Upstream, the cross-sectional flow of the flushing water connection does not change significantly; downstream, it widens slightly after the bend and narrowing 8 in terms of area, basically by an increasing height. This can be seen in Fig. 3 to some extent and in Fig. 4 as described below. Apart from that, the course of the flushing channel part 5 is straighter downstream, and the shape of the cross-section adapts to the vertical shape of the flushing nozzle 6, as can be seen in Fig. 3A in comparison to Fig. 2.

In the narrowing 8, two fluid dynamic effects occur at the same time, namely the generation of a static under-pressure at the inner side of the bend due to centrifugal forces on the one hand and a Venturi effect due to the step 7 by increasing the flow velocity within the narrowing 8 on the other hand. Combining these effects helps keeping the odour extraction unit free of water without additional measures such as valves or flaps.

In the region of the narrowing 8, a suck-off connection 9 is provided at the inside of the bend, the smallest cross-section of which is about 5 cm ² and about half as large as the cross-section of flow of the flushing channel in the narrowing 8, thus (therein, only the circular portion is considered and not the portion of the connection 9); it amounts to about 1/3 of the cross-section upstream thereof.

A pot-like water separator 10 follows on the correspondingly narrowed passage of this suck-off connection 9. Fig. 3C shows the flushing channel 5 within the narrowing 8 and the transition through the suck-off connection 9 to the water separator 10. A significantly enlarged cross-section of the water separator 10 in comparison to the suck-off connection upstream thereof can be seen as well as a bottom of the water separator 10 sloping slightly towards the flushing channel 5. Thus, the water, even when entering the water separator, flows back finally.

Particularly in Figs. 3A and 3B, two connecting pieces can be seen at the upper side of the water separator 10. A first one is referenced with 11 and is provided at a side of the water separator 10, being opposite to the flow direction of the water, and in an upper region thereof. It can be also seen in Fig. 3C. Thereto, the actual odour extraction unit 13 is connected, which is symbolically shown in Figs. 1 and 2 and is further explained by means of Fig. 4 (Figs. 1 and 2 show a suck-off channel 12 which is connected to the connecting piece 1 and leads to a fan 13 shown symbolically, which comprises an odour filter which is not shown).

The second connecting piece is referenced with 12 and is also explained by means of Fig. 4.

In particular, the water separator 10 ensures that, even though the odour extraction unit is in use, no water is sucked in during the end of the flushing process when the water velocity in the flushing channel part 5 and, thus, the centrifugal forces in the aforementioned bend decrease. When the static negative pressure generated by the velocity can no longer compensate the negative pressure of the fan, a water droplet can enter through the suck-off connection 9. However, the air is significantly slowed down in the water separator due to the widening of the cross-section so that the water remains in the lower part of the water separator 10.

Fig. 4 shows a perspective view of a part of the WC according to this embodiment, which is partly not shown in Figs. 1 and 2. The viewing direction is from the back obliquely to the front. The relation to Figs. 1 and 2 is easily derivable from the course of the flushing channel part 5 with the step 7 and the narrowing 8 and the flushing water connection 4 on the right in Fig. 4. Approximately above the middle of the flushing channel part 5, the water separator 10 is visible in Fig. 4; the connecting piece 11 for the odour extraction unit and the respective suck-off channel 12 can be seen pointing to the front and to the right from the water separator 10 on (in Fig. 4). The channel 12 leads to a filter box 13 in the front on the left, which comprises a fan for suction. The small quadratic connecting piece pointing to the front and to the right in Fig. 4 carries the filter, while the larger rectangular opening to the top is provided for provision purposes. Apart from that, it can be seen that the actual geometric arrangement of the line 12 and the filter box 13 differs slightly from Figs. 1 and 2 and that the WC bowl 1 is not shown in Fig. 4. From the water separator 10, a further channel line 13 leads backward to the left via the connecting piece 12 downward and is connected to a water tank 14 of a shower unit as an overflow. The water tank 14 has approximately the shape of a horseshoe, namely for an adaption to the bend of the siphon of the WC pointing upwards. The water tank 14 contains the shower water for the shower arm shown in Fig. 4 on the top right; in use, the shower arm can be pulled in and out through the passage through in the WC bowl 1, which is drawn in Fig. 2. The water tank 14 comprises a heating means and is a boiler for warm shower water, thus. The structure drawn on the right in front of the shower arm 15 is the electric drive for pulling out and in the shower arm.

If an overflow of the water tank 14 occurs for instance due to a fault, the water drains safely through the channel 13 and the water separator 10 and finally through the flushing channel into the WC bowl 1 , namely through the drain thereof. Therein, the odour extraction unit is not affected, because the channel 12 reaches a sufficient height. Apart from that, there is no risk of unintendedly sucking in false air through the channel 13, because the water tank 14 is filled with water when in operating condition.