Baths – closets – sinks – and spittoons – Flush closet – Bowl
Reexamination Certificate
1999-12-23
2001-04-17
Huson, Gregory L. (Department: 3751)
Baths, closets, sinks, and spittoons
Flush closet
Bowl
C004S321000, C004S323000, C004S434000
Reexamination Certificate
active
06216285
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a vacuum sewer system for transporting waste to a collecting container, municipal sewer, or the like.
BACKGROUND OF THE INVENTION
One basic problem with vacuum sewer systems relates to the high noise they produce. The noise occurs when the sewer valve opens and closes and when air is drawn into the open sewer. The vacuum sewer technique requires a relatively great volume of air to rapidly flow into the sewer immediately following the material to be transported. Further, the sewer valve must open and close rapidly. These functions cause considerable noise reducing pressure variations.
Reducing the noise level in a large vacuum sewer system is particularly difficult, because a large system has a greater total volume. As a result, large vacuum sewer systems typically require an intake of large amounts of air.
SUMMARY OF THE INVENTION
An object of the present invention is to create a sewer arrangement that is entirely based on the vacuum sewer technique and is adapted for use in a large vacuum sewer system, in which arrangement the noise level is low and in which the function control is easy to perform. The characteristic features of the invention are stated in the claims. A vacuum sewer system of this kind combines the advantages of the vacuum sewer technique with a low noise level in spite of a large sewer volume.
The invention is based on two observations. First, less noise is produced if lesser amounts of air have to be let into the sewer through a sanitary unit, e.g. a toilet. Secondly, the noise level is reduced, if the average speed of the air stream in question can be lowered during the emptying of a sanitary unit.
According to the invention, the emptying of and the waste transport from a sanitary unit, e.g. a toilet, is made in two stages, both of which take part in a sewer under vacuum. In the first stage, waste transport is performed, as known per se, through a first sewer portion into an intermediate container under vacuum. This makes it possible to keep the transport distance short and the applied volume under vacuum relatively small. Irrespective of the total size of the vacuum sewer system, the first stage of waste transport can be carried out in a system of standard design, which improves functional reliability because a standard system can be trimmed to optimize its functionality. Small-size vacuum sewer devices having this type of initial function are known from U.S. Pat. No. 5,133,853. Their primary weakness lies in the fact that the vacuum induced waste transport ends in the intermediate container. From there on the waste must be transported by pressurized air or by another pressure agent, which would be really troublesome in a large system. According to the invention, the entire waste transport mechanism is based on vacuum sewer technique, and no pressure agent other than ambient air is needed in any transport stage. Consequently, a system according to the invention can be used in large vacuum sewer networks, such as in passenger vessels or hotels. Because of the specific characteristics of the invention, the size of the vacuum network has no negative influence on the noise level.
It is of advantage that a system according to the invention includes means for controlling the first stage of waste transport so that the air flowing into the intermediate container via the sanitary unit raises the pressure in the intermediate container to at least close to the pressure of the ambient air. This reduces the average speed of the air flow, which reduces the noise level. On the other hand, it is suitable to dimension the intermediate container so that, after the first transport stage, it contains a sufficient volume of air to allow the second waste transport stage to be carried out without feeding external air to the intermediate container or to the sewer portion downstream thereof. If no external air feed is needed, the system structure remains fairly uncomplicated and the number of possible leak points is reduced. If the sanitary unit is a toilet, it is recommended that the volume of the intermediate container be at least 4 liters. It should preferably be considerably greater, for instance 10 to 15 liters.
In a preferred embodiment, the downstream end of the first sewer portion is formed in an inverted U-shape which empties into the upper portion of the intermediate container. The downstream end of the first sewer portion should be at a clearly higher level than the surface of the sewage collected in the intermediate container. Thereby, the air volume contained in the intermediate container as well as in the first sewer portion is available in a technically advantageous manner for the second stage of waste transport.
If the first sewer portion is kept fairly short, the waste transport taking part therein causes as little noise as possible. Generally, it is of advantage, that the first sewer portion has a total length, from its sewer valve to its downstream end in the intermediate container, of at the most 3 m, preferably at the most 2 m.
In a vacuum sewer, the transport of material, in particular closely downstream of a sanitary unit, is generally performed most securely in a direction upwards. Hence it is of advantage, if the downstream end of the first sewer portion is at a considerably higher level than its upstream end.
It is of advantage to use the same vacuum level, the so-called “system vacuum” maintained by means of the vacuum generating means of the system, in the first as well as in the second stage of waste transport. This vacuum level preferably sets the absolute pressure in the sewer to about 75 to 30% of the pressure of the ambient air. The best operational reliability is generally achieved if the absolute pressure in the sewer is about 65 to 40% of the pressure of the ambient air.
The efficiency of the first stage of waste transport is improved, if the volume of the intermediate container is made variable and controllable by means of a movable means, for instance a membrane, a piston or the like. The idea is to keep the volume of the intermediate container small at the beginning of the first stage of waste transport and enlarge it at the end of the same stage. This enhances the efficiency of the first stage of waste transport. In an advantageous embodiment, the means controlling the volume of the intermediate container is pressure operated, preferably operated by means of the “system vacuum”. Thus, a change of the volume of the intermediate container can be adapted to the first stage of waste transport, so that the volume of the intermediate container is automatically considerably smaller at the beginning of the first stage of transport than at the end of the same stage. It is of advantage to have a time related interconnection between the function of volume control means and the function of the sewer valve. This can be obtained if the volume change is pneumatically controlled through the operational means of the sewer valve. Such a system gives the best prospects for controlling the volume of the intermediate container in a manner best serving the function of the system. At the same time the structure of the control means remains fairly uncomplicated and is based on a control technique already previously used in vacuum sewer systems.
The structure of a system according to the invention can be simplified by arranging the connection of the intermediate container to a second sewer portion through a second sewer valve, having its opening and closing movement functionally connected to the function of the sewer valve of the sanitary unit connected to the first sewer portion. The basic idea is that when one sewer valve opens the other closes and vice versa. Such a functional connection can be easily obtained by arranging the sewer pipes so that both sewer valves are close to one another so that their operating mechanisms can be mechanically interconnected. Alternatively, both sewer portions may be connected to the same disc valve, so that a through-flow opening in the valve disc can take a posi
Evac International Oy
Huson Gregory L.
Marshall O'Toole Gerstein Murray & Borun
Nguyen Tuan
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