Title:
Toilet system with reduced or eliminated flushing requirement, especially for transportation vehicles
Kind Code:
A1


Abstract:
A toilet system, especially for passenger transport vehicles, includes a toilet bowl connected via a suction valve and a waste collection pipe to a waste collection tank. Waste-contacting surfaces of the toilet system that come into contact with urine and fecal waste are coated with an adhesion-inhibiting or adhesion-reducing nanocoating. Thereby, the adhesion of waste to the toilet bowl and other components is significantly reduced, and the total flushing water demand can be substantially reduced or, preferably completely eliminated. An airflow flowing into the toilet bowl, induced by the vacuum suction through the suction valve, is sufficient to “flush” the waste material from the nanocoated waste-contacting surfaces. The toilet system provides a substantial reduction in the total system weight and in the required quantity of flushing water that must be carried in the vehicle, and thus makes the toilet system particularly applicable for passenger transport vehicles such as aircraft.



Inventors:
Erdmann, Wolfgang (Buxtehude, DE)
Gienke, Torsten (Pinneberg, DE)
Heinrich, Hans-juergen (Hamburg, DE)
Application Number:
10/017491
Publication Date:
08/22/2002
Filing Date:
10/22/2001
Assignee:
ERDMANN WOLFGANG
GIENKE TORSTEN
HEINRICH HANS-JUERGEN
Primary Class:
International Classes:
B64D11/02; E03D11/02; E03F1/00; (IPC1-7): E03D1/00
View Patent Images:
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Primary Examiner:
FETSUGA, ROBERT M
Attorney, Agent or Firm:
FASSE PATENT ATTORNEYS, P.A. (HAMPDEN, ME, US)
Claims:

What is claimed is:



1. A toilet system for collecting waste material including at least one of urine and feces, said system comprising: a toilet bowl with a bowl outlet and a first waste-contacting surface adapted to come into contact with the waste material; a waste discharge arrangement that is adapted to convey the waste material from said toilet bowl, and that includes a waste pipe connected to said bowl outlet and adapted to convey the waste material therethrough, a waste collection tank connected to said bowl outlet by said waste pipe and adapted to receive and collect the waste material therein, and a waste suction valve connected and interposed in said waste pipe between said bowl outlet and said waste collection tank, wherein at least one of said waste pipe, said waste collection tank and said waste suction valve has a second waste-contacting surface adapted to come into contact with the waste material; and a suction source connected to said waste discharge arrangement and adapted to provide a suction airflow that flows into said toilet bowl from an outside environment outside of said toilet bowl, flows along said first waste-contacting surface, and flows out of said toilet bowl through said suction valve when said suction valve is open, such that said suction airflow assists in removing the waste material from said toilet bowl; and wherein at least one of said toilet bowl and said waste discharge arrangement comprises a structural substrate and a nanocoating disposed directly or indirectly on said structural substrate so that said nanocoating forms at least one of said first waste-contacting surface and said second waste-contacting surface.

2. The toilet system according to claim 1, further comprising an air jet arrangement that communicates from the outside environment outside of said toilet bowl into said toilet bowl and that is arranged and adapted to direct an air stream along said first waste-contacting surface.

3. The toilet system according to claim 2, further comprising a toilet lid adapted to selectively close and open a top opening of said toilet bowl, wherein said air jet arrangement includes at least one air nozzle oriented to direct the air stream along said first waste-contacting surface.

4. The toilet system according to claim 2, arranged and adapted so that the suction airflow through said suction valve drives the air stream from the outside environment through said air jet arrangement into said toilet bowl as at least a part of a totality of said airflow.

5. The toilet system according to claim 1, wherein at least one of said waste pipe, said waste valve and said waste collection tank comprises said structural substrate and said nanocoating.

6. The toilet system according to claim 1, wherein said toilet bowl comprises said structural substrate and said nanocoating, and wherein said first waste-contacting surface is at least a portion of an inner bowl surface of said toilet bowl.

7. The toilet system according to claim 6, wherein said nanocoating is a thin film having a thickness in a nanometer range, and wherein said thin film has been formed by a nanotechnology process.

8. The toilet system according to claim 1, expressly excluding all means of supplying a flushing liquid into said toilet bowl.

9. The toilet system according to claim 1, further comprising a base layer arranged between said nanocoating and said structural substrate, so that said nanocoating is disposed indirectly on said structural substrate with said base layer therebetween.

10. The toilet system according to claim 1, wherein said nanocoating is disposed directly on and in contact with said structural substrate.

11. The toilet system according to claim 1, wherein said nanocoating consists essentially of a metal.

12. The toilet system according to claim 1, wherein said nanocoating consists essentially of a polymer.

13. The toilet system according to claim 1, wherein said nanocoating consists essentially of an element of the fourth group of the periodic table.

14. The toilet system according to claim 1, wherein said nanocoating consists essentially of at least one element selected from the group consisting of Cr, Ti, Mn, Ni, Ta, Al, V, W, Co, Be, Zr, Hf, Nb, Mo, C, Si, Ge and Sn.

15. The toilet system according to claim 1, wherein said nanocoating consists essentially of at least one metal carbide.

16. The toilet system according to claim 1, wherein said nanocoating consists essentially of at least one of a metal nitride and a metal boride.

17. The toilet system according to claim 1, wherein said nanocoating consists essentially of at least one compound having a covalent bonding property.

18. The toilet system according to claim 1, wherein said nanocoating consists essentially of at least one compound having an ionic bonding property.

19. The toilet system according to claim 1, wherein said nanocoating consists essentially of a sialon compound.

20. The toilet system according to claim 1, wherein said nanocoating consists essentially of a nanocomposition of organic and inorganic components, and wherein said nanocomposition has a low surface energy.

21. The toilet system according to claim 1, wherein said nanocoating has such a character that it provides a wetting angle of 0° to 10° with respect to a droplet of the waste material.

22. The toilet system according to claim 1, wherein said structural substrate on which said nanocoating is disposed has a maximum substrate surface roughness of less than 100 nm and a mean substrate surface roughness of less than 10 nm.

23. A toilet system for collecting waste material including at least one of feces and urine, comprising: a toilet bowl comprising a bowl structure substrate, a bowl outlet, and a nanocoating that is provided on at least a portion of an inner bowl surface of said bowl structure substrate and that forms a first waste-contacting surface adapted to come into contact with the waste material; a waste discharge arrangement that is adapted to convey the waste material from said toilet bowl, and that includes a waste pipe connected to said bowl outlet and adapted to convey the waste material therethrough, a waste collection tank connected to said bowl outlet by said waste pipe and adapted to receive and collect the waste material therein, and a waste suction valve connected and interposed in said waste pipe between said bowl outlet and said waste collection tank, wherein at least one of said waste pipe, said waste collection tank and said waste suction valve has a second waste-contacting surface adapted to come into contact with the waste material; a suction source connected to said waste discharge arrangement and adapted to provide a suction airflow from said toilet bowl through said suction valve when said suction valve is open, such that said suction airflow assists in removing the waste material from said toilet bowl; and air directing means that direct at least a portion of said airflow along said first waste-contacting surface downwardly toward said bowl outlet; and expressly excluding all means of supplying a flushing liquid into said toilet bowl.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a Continuation-in-Part under 35 U.S.C. §120 of our prior co-pending U.S. patent application Ser. No. 09/603,854, filed on Jun. 26, 2000.

PRIORITY CLAIM

[0002] This application claims the priority under 35 U.S.C. §119 of German Patent Application 199 28 894.1, filed on Jun. 24, 1999.

FIELD OF THE INVENTION

[0003] The invention relates to a toilet system, especially for transportation vehicles, including at least one toilet bowl connected to a waste collection tank by a suction valve.

BACKGROUND INFORMATION

[0004] Transportation vehicles, particularly aircraft, have only a limited capacity for carrying flushing liquid for rinsing or flushing toilets and waste water. For this reason, transportation vehicles often use toilet systems in which the toilet bowl is connected to a waste collection tank by a suction valve, and particularly toilet systems that are constructed as vacuum systems. Conventional toilet systems use a flushing liquid to flush the toilet bowl, whereby the flushing liquid can be fresh water or can be in part so-called gray water, i.e., fresh water that has already been used for hand washing or the like and may be supplemented by deodorizers, disinfectants, etc. The flushing liquid is sometimes referred to as “flush water” herein for simplicity.

[0005] German Patent 42 01 986 and corresponding U.S. Pat. No. 5,317,763 (Frank et al.), issued June 1994, disclose a vacuum toilet that is essentially equipped with a trigger device, a flush water valve, and a suction valve that is arranged in a connecting conduit between the toilet bowl and the waste collection tank. After the trigger is actuated, the flushing liquid is delivered to the toilet bowl by means of control devices. Subsequently, the suction valve opens and the waste contained in the toilet bowl is flushed together with the flushing liquid into the waste collection tank.

[0006] A brochure titled “Das Zentrale Vakuum Toiletten-System für die Schiffsausrüstung” (“The Central Vacuum Toilet System for the Outfitting of Ships”) from the company sanivac Vakuumtechnik GmbH of Wedel, Germany (1997) discloses a vacuum toilet system that is used for marine vessels. This system, too, requires less flushing water than the conventional gravity flush toilet systems because of the use of vacuum technology that reduces the demand for flushing liquid to approximately 1 liter per flush. This reference also discloses that the waste pipe of the system may be a steel pipe with an inner surface coating of plastic.

[0007] German Utility Model Publication DE 92 01 684 U1 discloses a toilet arrangement in which an odor-binding agent or cleaning agent is added to the flushing liquid in the flushing circuit. This increases the effectiveness of the toilet flushing and reduces the formation of odor. This reference further suggested coating the toilet bowl with a layer of polytetrafluoroethylene (PTFE), to facilitate the cleansing or flushing of fecal residue from the toilet bowl.

[0008] European Patent Publications EP 0,295,508 and EP 0,363,012 disclose vacuum toilet systems that use “gray water”, at least in part, for rinsing or flushing the toilet bowl. In these cases, it is necessary that the water previously used in the wash basins be processed with a suitable filter technology in order to prevent blockage of the flush water line. Thus, in addition to the necessary controls for the flushing process, it is also necessary with such systems to provide a water treatment process. Various attempts have been made to provide waterless toilet systems, i.e. toilet systems that do not require a flushing liquid for flushing the urine and fecal waste from the toilet bowl, e.g. U.S. Pat. No. 3,457,567 (Criss) and U.S. Pat. No. 4,346,002 (Petzinger). These are generally composting toilet systems that use a cone or wrapper of paper or plastic for encapsulating the fecal waste in the toilet bowl and then transporting the resulting encapsulated package by vacuum suction through a waste line to a holding/composting tank. The encapsulating wrapper aims to prevent direct contact of the fecal waste with the inner surfaces of the toilet bowl, which of course avoids the need of cleaning or removing the fecal waste from the inner surfaces of the toilet bowl. In other words, such systems do not have any waste-contacting surfaces in the toilet bowl or waste lines, because the waste is fully encapsulated in a wrapper. Such systems are not well suited to applications in commercial passenger transport vehicles, because they are not sufficiently robust and reliable. For example, experience has shown that passengers often try to dispose of various items in addition to feces and urine in the toilets, including feminine hygiene products, bottle caps, razor blades, wrappers and packaging of various products, etc. Such items will inevitably puncture the waste-encapsulating wrapper, causing feces to directly contact, soil and adhere to the inner surfaces of the toilet bowl and waste line. Also in such systems, the wrapper-providing arrangement is very subject to failure, and/or requires proper operating efforts and procedures by the toilet user.

[0009] Reducing the amount of water or liquid required for flushing the toilets is of great importance, particularly on board an aircraft. On large capacity aircraft, for example that can carry up to 500 passengers, sufficient water for flushing the toilets (fresh water or “gray water”) must be provided for each passenger to use the toilet, with further consideration of the duration of the flight. Although a number of toilet systems that require a reduced volume of flushing liquid are already known, it is still important and necessary, particularly for large capacity aircraft, to reduce to a minimum (or entirely eliminate) the water demand for flushing and rinsing purposes. This is particularly true for large capacity aircraft that fly long distances (i.e. long flight durations) and, accordingly, must otherwise carry an enormous amount of water. The toilet system for an aircraft must also have a high reliability, ease of use, and low maintenance requirement.

SUMMARY OF THE INVENTION

[0010] For the above reasons it is an object of the invention to provide a toilet system that provides a further weight reduction compared to the conventional systems. It is a further object to minimize or completely eliminate the necessity for flush water and thereby to simplify the system and provide a toilet system that is particularly suitable for use in large capacity aircraft. Another object is to provide a method of manufacturing such an improved toilet bowl for a toilet system. The invention further aims to avoid or overcome the disadvantages of the prior art and to achieve additional advantages, as are apparent from the present specification.

[0011] The above objects have been achieved in a toilet system according to the invention in which the toilet bowl is connected by a suction valve to a waste collection tank, and in which at least some of the system components that come into contact with waste material are provided with a nanocoating. Particularly at least a portion of the inner bowl surface of the toilet bowl itself is provided with a thin film coating deposited by nanotechnology processes. The nanocoating is provided at least on the entirety of the waste-contacting inner surface area of the toilet bowl, preferably the nanocoating may cover a whole inner surface of the toilet bowl. Such a nanocoating significantly reduces or eliminates the adhesion of fecal residue and other wastes on the waste-contacting surfaces of the toilet bowl, the waste line, the flush valve, and/or the waste tank, and therefore reduces or eliminates the demand for flushing liquid. The nanocoating also avoids the need to provide wrappers or the like for encapsulating the fecal waste in the toilet bowl, as in some prior art systems. These features in turn simplify and reduce the weight of the overall toilet system.

[0012] The toilet system according to the invention is particularly advantageous because it provides a substantial reduction in weight relative to the conventional systems. This is especially important for the use of such toilet systems in aircraft. The overall amount of flush water or liquid required for rinsing or flushing the toilet can be substantially reduced or can even be completely eliminated. The weight that is saved due to the elimination or reduction of flush water can be used, for example, to allow increasing the seating capacity in the transportation vehicle.

[0013] The invention further provides a method for manufacturing a toilet system according to the invention. The surface of the toilet bowl to be coated with the nanocoating can be pretreated with grinding, polishing and surface cleaning operations. The nanocoating can be applied by means of cathodic sputtering or gas phase deposition processes such as chemical vapor deposition or physical vapor deposition processes. Waste contamination and adhesion of particles can be avoided particularly by applying the nanocoating to the waste-contacting surface portion of the toilet bowl that comes into contact with waste materials or is exposed to a passenger.

[0014] In a further embodiment of the toilet system according to the invention, the flush water and, consequently, the flush water circuit, can be completely eliminated. This simplifies the system by reducing the number of its components, and reduces the maintenance and repair effort. By applying suction through the toilet bowl outlet during the toilet bowl emptying process, an airflow is sucked from the surrounding environment into the bowl and downwardly to the bowl outlet, which assists in sweeping and removing the fecal and urine waste from the nano-coated waste-contacting surfaces of the bowl downwardly to the bowl outlet. Optionally, the airflow can be enhanced or especially directed along the waste-contacting surfaces by airflow directing means such as an air jet arrangement (passive or active) or simple airflow openings that direct the airflow toward and along the waste-contacting surfaces. By means of this airflow, it is possible to achieve good cleansing of the nano-coated waste-contacting surfaces of the toilet bowl, with or without a minimum of flush water, or simply with a very small amount of a deodorizer and disinfectant.

[0015] According to the invention there are several alternatives for forming the adhesion-inhibiting, or at least adhesion-reducing, coatings. The nanocoating is preferably made of a metal, or an element of the fourth major group of the periodic system, or of a composition with a covalent bonding character or an ionic bonding character. Alternatively, the nanocoating can consist of a sialon composition, that is, an alloy of silicon nitride and aluminum oxide, or a polymer. The nanocoating is preferably applied to surfaces of the system components that are within the toilet bowl area and/or come into contact with waste material. A base layer may be applied to the area of the toilet bowl to which the nanocoating will subsequently be applied to improve the retention of the adhesion-inhibiting or at least adhesion-reducing coating.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order that the invention may be clearly understood, it will now be described in connection with example embodiments, with reference to the accompanying drawings, wherein:

[0017] FIG. 1 is a schematic diagram of a first embodiment of a vacuum toilet system with a toilet bowl according to the invention using a reduced amount of flushing liquid;

[0018] FIG. 2 is a schematic diagram of a second embodiment of a vacuum toilet system with a toilet bowl according to the invention entirely omitting the use of a flushing liquid;

[0019] FIG. 2A is a schematic diagram of a variation of the toilet bowl of the second embodiment of FIG. 2;

[0020] FIG. 3 represents a wetting angle of a conventional surface without coating;

[0021] FIG. 4 represents a wetting angle of a surface coated with a nanocoating according to the invention;

[0022] FIG. 5 schematically shows a toilet bowl according to the invention; and

[0023] FIG. 5A shows the detail area 5A of the coating on the toilet bowl of FIG. 5.

DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BEST MODE OF THE INVENTION

[0024] FIG. 1 is a schematic representation of a toilet system 1 such as can be used in an aircraft A. The toilet system 1 comprises essentially at least one toilet bowl 2 that is connected via a waste water valve 3 to a waste collection pipe 4. It is possible to connect a plurality of toilets located at various locations to the waste collection pipe 4. The waste collection pipe 4 includes pipes, conduits, hoses, or lines that are used to convey waste material. The waste collection pipe 4 leads to a waste collection tank 5 in which the waste material and waste water are collected. A pressure differential between the toilet bowl 2, which contains waste, and the waste collection tank 5 facilitates or effectuates the waste transport operation. The toilet system 1 is constructed therefor as a vacuum toilet system. A vacuum generator 6 generates the necessary negative pressure. When used in an aircraft, the vacuum toilet system 1 can also or alternatively take advantage of the predominating reduced external atmospheric pressure during flight to provide the pressure differential required for proper functioning of the vacuum toilet system 1.

[0025] The waste collection tank 5 is further connected to a tank drain valve 7 by means of which the collected waste water can be discharged as needed. A flushing liquid dispenser, which is a rinse or flush ring 8 in the example embodiments but may have any conventionally known arrangement of a flushing liquid dispenser, is provided on the toilet bowl 2. Instead of the flush ring 8, it is possible to use other liquid dispensing means, such as one or more individual water jets or nozzles arranged in the toilet bowl 2. The flush liquid or water is guided from the flush ring 8 into the toilet bowl 2 and cleanses the toilet bowl 2 during a flushing operation. The flush water is drawn from a flush water tank 9 that is connected by a feed line 10 and a flush water valve 11 to the toilet bowl 2 (and particularly the flush ring 8) to be flushed or cleaned. A control unit 12 controls the actions of the waste water valve 3 and the flush water valve 11, responsive to the actuation of a flush control button 12A that can be depressed by a passenger who has used the toilet.

[0026] After the toilet has been used, the flushing operation is initiated by the passenger by actuating the flush control button 12A or other trigger device to convey the fecal materials or other waste material from the toilet into the waste collection tank 5. The control unit 12 opens the flush water valve 11 and flush water is sprayed or guided into the toilet bowl 2 from the flush ring 8 (for example, by means of spray jets, which will keep the amount of flush water required for flushing as low as possible). The waste water, i.e., fecal material and flush water, collects by the force of gravity in a toilet drain 2B of the toilet bowl 2. The waste water valve 3 then opens for a brief time and the waste material that is collected in the toilet bowl 2 is conveyed out of the toilet bowl through the bowl outlet or drain 2B, through the valve 3 and into the waste collection pipe 4, and from there into the waste collection tank 5 by means of the pressure differential. An airflow A that flows into the toilet bowl, being induced by the just-mentioned pressure differential and suction out of the bowl through the drain 2B, additionally “flushes” or “sweeps” the waste material out of the bowl 2 through the drain 2B, as will be further described below.

[0027] Flush water is necessary in conventional toilet systems in order to clean the toilet bowl 2 of any waste material that remains adhered to the inner surfaces of the toilet bowl 2. In order to remove such waste or contamination with only a very small amount of flush water or even without flush water, a relevant surface area of the toilet bowl 2 according to the invention is coated with a special nanocoating 15. The nanocoating 15 is applied to the complete inside surface of the toilet bowl 2 or at least in a waste-contacting surface area 2A that comes into contact with the waste material, as indicated in FIGS. 1, 2, and 5. The structure and the mode of manufacturing the nanocoating 15 is shown in more detail in the FIGS. 3 to 5 and described in more detail below. The nanocoating 15 has adhesion-inhibiting or at least adhesion-reducing properties.

[0028] The first example embodiment of the toilet system 1, shown in FIG. 1, uses a nano-coated toilet bowl 2 that requires a greatly reduced amount of water for cleaning or flushing, relative to conventional toilet bowls. This is achieved because the nanocoating 15 minimizes or prevents the adhesion of urine and fecal waste material onto the inner surfaces of the toilet bowl 2, so that the above mentioned airflow A together with a minimal amount of flushing liquid and the effect of gravity are sufficient to remove the waste material from the bowl 2 out through the drain 2B during a flushing operation. Thus, particularly for large capacity aircraft that fly long distances, the amount of water required for flushing toilets is substantially reduced. As a result, additional weight capacity is now available for additional passenger seats or for other measures that will increase the comfort of the passengers. Also, the waste collection tank 5 and the flush water tank 11 that are required can be made smaller, as they are now required to hold a lesser volume. This also results in a further reduction of weight.

[0029] FIG. 2 shows a toilet system 20 according to a second example embodiment of the invention. In this embodiment, the toilet system 20 comprises a nano-coated toilet bowl 2 to which essentially no waste material at all can adhere. Thus, with the toilet bowl 2 according to this embodiment, rinsing or flushing liquid to flush or clean the surface of the toilet bowl 2 is completely unnecessary. Consequently, system components such as the flush ring 8, the flush water tank 9 (or the fresh water feed line), the feed line 10 and the flush water valve 11 become superfluous and are thus not provided in the toilet system 20. This is a substantial simplification of the overall toilet system 20, which not only reduces the weight of the toilet system 20, but also reduces the cost and effort of maintenance and repair.

[0030] The toilet bowl 2 of the toilet system 20 is provided with a nanocoating 15 at least in the waste-contacting area 2A shown in FIG. 5. This is the area where waste material comes into contact with the surface of the toilet bowl 2. Due to the elimination of the flush water valve 11, maintenance measures for cleaning, decalcifying and replacing the seal elements of this valve 11 are also eliminated and the overall reliability of the system increases since leakages in the flush water circuit are also eliminated. Moreover, the advantages mentioned in connection with the toilet system 1 also apply to the toilet system 20.

[0031] The remaining system components of the toilet system 20 are identical with those of the toilet system 1 shown in FIG. 1. The elimination of the flush water feed simplifies the system control and therefore the control unit 12 can also be simplified. With the elimination of the flush water circuit, only the opening and closing of the waste valve 3 is necessary to remove the collected waste material from the toilet bowl 2. In other words, it is no longer necessary to actuate a flush water valve in proper coordination with the waste valve 3. Instead, the waste material easily “slides” down from the nanocoated waste-contacting surfaces 2A, so that the waste material is completely removed from the toilet bowl 2 by the combined effects of gravity and the induced airflow A, without needing any flushing liquid. Namely, the waste material is conveyed out of the toilet bowl 2 primarily by means of the suction created by the vacuum that exists within the toilet system, which in turn induces the airflow A into the toilet bowl as described above, when the suction waste valve 3 is opened. The airflow A is thereby caused to flow from the surrounding environment outside of the toilet bowl 2, into the bowl 2, and particularly directed downwardly along the nanocoated waste-contacting surfaces 2A toward the outlet 2B. Moreover, the downward force of gravity acts advantageously on the waste that falls onto the surface of the toilet bowl 2 because of the minimal adhesion properties of the nanocoating 15 provided on the waste-contacting surfaces 2A of the toilet bowl 2. After the waste material has been removed, the toilet bowl 2 is left in a clean condition without having to be flushed with liquid.

[0032] As a further auxiliary alternative exemplified in FIG. 2A, the toilet bowl 2 may be additionally equipped with airflow directing means to passively or actively direct an airflow forcefully along the waste-contacting surfaces 2A of the toilet bowl 2. In the example of FIG. 2A, an air jet arrangement with air jets 27 is provided instead of the water spraying flush ring 8 of FIG. 1, so that one or more directed air jets blow downward along the inner surfaces of the bowl to assist in moving any remaining waste material down into the toilet drain 2B. For example, such air jets 27 may be driven actively by a source of pressurized air, or passively from the room air outside of the toilet bowl due to the airflow induced into the bowl upon opening the suction waste valve 3. The air jets 27 may optionally be formed by air-directing configurations on the bottom of a toilet seat provided on the toilet bowl. As a further optional component, the toilet may be equipped with a cover or lid 28, which selectively covers the bowl 2 in the usual fashion and/or also enhances the passive flow of outside air through the air jets. For this purpose, the cover 28 may optionally be adapted to close the top opening of the bowl sufficiently tightly to cause at least most of the induced airflow A to enter the bowl through the air jets 27, if the cover 28 is closed before actuating the suction waste valve 3.

[0033] FIGS. 3 and 4 illustrate to what extent a nanocoating will reduce the wetting angle of a liquid or waste droplet 13 on the surface 14 of a toilet bowl 2. FIG. 3 shows a conventional surface 14′ without a coating or, for example, with a PTFE-coated toilet bowl. A droplet 13 of water or urine or feces is located on the surface 14 of the toilet bowl 2. The wetting angle 13A is relatively large (e.g. 65°) in the conventional toilet bowl 2 and thus the droplet 13 can adhere to the surface 14′.

[0034] FIG. 4 illustrates a wetting angle 13B of a droplet 13 on the surface 14 of a toilet bowl 2 that is coated with a nanocoating 15 according to the invention. As can be seen, the wetting angle 13B on the nano-coated toilet bowl 2 is much smaller than that of the uncoated toilet bowl shown in FIG. 3, and, as a result, the droplet 13 will have a significantly reduced wetting adhesion on the surface and will glide or roll over the surface of the nano-coated toilet bowl 2 much more easily, simply under the force of gravity. For example the wetting angle 13B may be in a range from 0° to 25°, or preferably 0° to 10°.

[0035] The nanocoating 15 is produced by means of nano-technology and is applied to the surface 14. The nanocoating 15 has a coating thickness in the nanometer range, e.g. less than 10 nanometers, or preferably less than 5 nanometers. Nanotechnology provides ordered surfaces with a low surface energy, such that when such a surface is wetted by a droplet, the wetting angle 13B approaches 0°, thereby providing a best possible achievable anti-adhesion coating. This anti-adhesion nanocoating 15 inhibits or at least substantially reduces the adhesion of the droplet 13 of water or urine or particles of fecal matter to the surfaces of the toilet bowl 2 and/or other components of the toilet systems shown in FIGS. 1 and 2 that are coated with the nanocoating 15. The droplets 13 fall under the force of gravity into the drain 2B of the toilet bowl 2, which is also preferably coated, and are then suctioned off by the effect of the vacuum via the waste collection pipe 4 into the waste collection tank 5.

[0036] FIG. 5 shows a detail of the toilet bowl 2 according to the invention and FIG. 5A shows a much enlarged sectional view of the nanocoating 15 on the surface of the toilet bowl 2. Preferably, the base material or structural substrate 2′ of the toilet bowl 2 is made of stainless steel, in view of its corrosion-inhibiting properties, and its ductility or lack of brittleness. Synthetic materials, e.g. plastics, however, may also be used for the toilet bowl 2 and for other components of the toilet system.

[0037] In the embodiment shown in FIGS. 5 and 5A, the substrate 2′ of the toilet bowl 2 is first coated with a base coating 16. The base coating 16 may be necessary in some cases, for example, when it is difficult to apply the nanocoating 15 directly to the base material or substrate of the toilet bowl for lack of adequate adhesion or because the roughness is too great. In such cases the nanocoating 15 can be produced with better results when applied to the intermediate base coating 16.

[0038] In a preferred embodiment, the surface of the toilet bowl to be coated is first pretreated before the base coating 16 or the nanocoating 15 is applied. The surface is first subjected to a grinding and polishing process in order to obtain a surface roughness in the range of less than 100 nm and a mean roughness in the range of less than 10 nm. Subsequently, the surface is cleaned with an organic solvent and/or by an ultrasound cleaning process.

[0039] The application of the nanocoating 15 to the toilet bowl 2 will now be described in greater detail. Preferably, metals or elements of the fourth major group of the periodic system, or alternatively and more particularly Cr, Ti, Mn, Ni, Ta, Al, V, W, Co, Be, Zr, Hf, Nb, Mo, C, Si, Ge or Sn, or compounds with these elements are used to make the nanocoating 15. It is possible to use compounds with a metallic bonding property, in particular carbides such as MC as well as secondary carbides M2C, M3C, M6C, M7C, M23C6, whereby M designates a metal or an intermetallic metal group. It is furthermore possible to use nitrides of the structure MN or borides of the structure MB, whereby, again, the M stands for a metal.

[0040] Alternatively, it is possible to produce the nanocoating 15 from a compound having a covalent bonding property such as, for example B4C, SiC, BN, Si3N4 or MOS2.

[0041] In a further alternative, the nanocoating 15 can be made from a composition having an ionic bonding property, such as, for example Al2O3 or ZrO2 or BeO. In a further embodiment the nanocoating 15 can be made from a sialon composition, i.e., an alloy of silicon nitride and aluminum oxide, or from polymers.

[0042] The nanocoating, also referred to as “thin films” or “ultra thin films”, can be produced by classic cathodic, or vapor deposition or sputtering methods, or by means of resistance heating through vacuum assisted processes. The demands on the production of a coating by means of nanotechnology are characterized by atomically precise boundaries and by controlling the deposition of layers that are each only one atom thick. For the most part, applied vacuum methods are based either on molecular beam epitaxy (MBE) or deposition from a gas phase.

[0043] Possible methods of production are, for example: cathodic sputtering; ionic implantation; sputter techniques (plasma beam source, magnetron sputtering, radio frequency diode sputtering); gas phase deposition (chemical vapor deposition—CVD, atomic layer epitaxy—ALE, and chemical beam epitaxy—CBE); plasma assisted chemical vapor deposition—PACVD; and physical vapor deposition—PVD.

[0044] As a further alternative, an anti-adhesion coating can be formed on the basis of inorganic-organic nanocompositions with a low surface energy. Such a coating can be formed by generally known coating techniques, such as dipping immersion, spray coating, or centrifugal spin coating or the like, followed by curing or hardening of the coating layer by UV-radiation and/or thermal heating, whereby the resulting nanoparticles of the coating achieve the desired anti-adhesion properties.

[0045] When producing the nanocoating 15 according to the possible methods, it is essential that the nanocoating is formed rather soft and non-brittle, as this will prevent parts of the nanocoating 15 from peeling from the toilet bowl 2.

[0046] The magnetron sputter technique is the preferred method of producing the nanocoating 15. This technique, which is generally known to the person of ordinary skill in the art, belongs to the group of methods referred to as cathodic sputtering. According to this method, the coating is applied in a vacuum and a solid base is coated with metallic or non-metallic layers. The coating material on the cathodes is atomized or sputtered by bombardment of the material with gas ions in a gas atmosphere. The material is then deposited on the toilet bowl substrate surface as a coating. The ions ensure that the upper atomic layers from the coating material are converted by impulse exchange into the gaseous state. The coating material, now in a gaseous state, is then deposited on the surface to be coated. The thermal stress on the toilet bowl substrate to be coated is relatively low when this magnetron sputtering technique is used. It is currently possible to attain a coating diameter of up to 150 mm, with a coating rate of 0.1 to 1 mm/min when using a double ring magnetron source. According to the invention, the nanocoating 15 is to be applied to rather large surface areas of the toilet bowl, and optionally other portions of the toilet system. Preferably, the whole inner surface of the toilet bowl 2 is to be coated.

[0047] Application of the nanocoating 15 to the toilet bowl 2 has been described in greater detail above. It is possible, of course, to apply the nanocoating 15 using suitable application methods to other components of the toilet system that come into contact with fecal material or other waste material. It is within the scope of the invention, for example, to coat the interior of the waste collection pipe 4, or at least portions of the waste collection pipe 4 such as branching areas, in order to reduce as much as possible the effort involved with cleaning and maintaining the toilet system.

[0048] Although the invention has been described with reference to specific example embodiments, it will be appreciated that it is intended to cover all modifications and equivalents within the scope of the appended claims. It should also be understood that the present disclosure includes all possible combinations of any individual features recited in any of the appended claims. The term toilet bowl herein includes all possible types and configurations of toilets including sit-down toilets, crouching-type toilets, urinals, etc.