Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Waste water lifting system

Waste water lifting system description/claims

This application is a continuation of international patent application no. PCT/EP2006/011966, filed Dec. 13, 2006, designating the United States of America, and published in German on Jun. 21, 2007 as WO 2007/068455, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application no. DE 10 2005 060 556.7, filed Dec. 17, 2005.

The present invention relates to a waste water lifting system comprising a collecting tank for liquids, in particular sewage, excrement or the like, and comprising a device for emptying the tank, in particular a pump which is connected to a motor and which is arranged as a motor pump unit wholly or partially lowered in the tank, the tank has at least one inlet and outlet pipe, respectively, for the liquids, and the waste water lifting system is provided with a device for switching the pump as a function of a liquid level within the tank.

Waste water lifting systems of this kind are frequently used as excrement lifting systems and are employed in buildings and plants when waste water to be conveyed accrues beneath a so-called backwash level. The backwash level is usually a height level of an external waste water system, which is disposed outside a building under a road. For a proper operation of such a waste water lifting system, devices for monitoring the liquid level within the tank are necessary in order to be able to ensure that the pump is switched on and off on time.

A waste water lifting system of this type for the collection and pumping-off of sewage water is known from published German patent application no. DE 33 11 980. To this end, the waste water lifting system has a collecting tank and a motor pump unit located therein, which receives its switching signals through a pneumatic control bell. This is constituted by a Pitot tube, the air volume of which, when a tank content is raised, is enclosed and thus generates a static pressure in the Pitot tube. This pressure is registered by a pressure sensor and its value converted into a fill level height of the respective tank. However, such dynamic pressure systems, which exist in a wide variety of forms, are susceptible to the sewage water, and its constituent parts, present within the tank. Since a failure of a relevant component of this kind is of fundamental significance for the entire system and the building whose waste it disposes, considerable servicing and maintenance works are necessary to ensure the functionality thereof. In order to prevent leaks or deposits within such a Pitot tube system, the tube must constantly be cleared in a complex manner by separate control elements or the above drawbacks can be prevented by the introduction of air bubbles.

Alternatively thereto, float switches, as are known, for example, from published German patent application no. DE 3,430,527, have gained market acceptance for controlling the pump. Depending on the liquid level within the tank, a float-actuated switch triggers the necessary switch-on and switch-off motions of a pump. These float switches also, however, are restricted or jeopardized in terms of their function by deposits or solid constituents in the liquid.

Against this background, it is an object of the present invention to provide a level registration system by which the fill level in the tank can be reliably registered without difficulty.

A further object of the invention is to provide a level registrations system which does not require use of complex, additional protective devices exposed to the liquid.

These and other objects have been achieved in accordance with the present invention by providing a waste water lifting system comprising a collecting tank for a liquid, the tank having at least one inlet and an outlet for the liquid; a device for emptying the tank; and a device for switching the tank emptying device on or off as a function of a liquid level within the tank; in which the tank comprises at least a partial area which is elastically resiliently deformable as a function of the liquid level in said tank, and at least one sensor is disposed on the outside of the tank for measuring deformation of the deformable tank area, the at least one sensor being operatively connected to the switching device for transmitting a measured deformation of the deformable tank area to the switching device as an indication of the liquid level in said tank.

Thus, in accordance with the present invention, the tank floor, or at least a part-area of the tank floor, may be configured such that it is elastically resilient as a function of the tank fill level, and one or more sensors are disposed on the outer side of the elastically resilient tank floor area and measure the deformation thereof.

With this arrangement, the problem of fill level sensors becoming contaminated is avoided. Since the sensors which register the degree of deformation of a tank floor part are fitted on the outer side of the tank, they are fully removed from the harmful influences of the waste water. As a result of the arrangement of the tank floor part at a distance from an installation area for the waste water lifting system, a cavity is formed therebetween. This cavity is simultaneously a protective space for the external sensors against external mechanical influences and prevents damage to the elastically resilient tank floor part.

The tank floor or a part-area thereof is designed such that at least one sensor is disposed at a tank floor measuring point at which an evaluable deformation occurs when the tank is maximally filled. Similarly, it is provided that at least one sensor is disposed at a tank floor measuring point at which an evaluable deformation occurs when the tank is minimally filled. The generation of sensor signals, with which the necessary switch-on, switch-off or alarm points of a waste water lifting system, or of the pump connected thereto, and the dependence on the respective fill level in the tank, can be reliably registered, is thus ensured. The deformation of load-imposing tank, which deformation here maximally occurs at a measuring point, lies within the respectively permitted material values. This is achieved by an appropriate shaping of the tank floor or of a part thereof.

It is likewise possible to arrange an elastically resilient element in a leaktight and flexibly held manner in the tank floor and to connect it to at least one sensor. A sensor signal above a respective fill level is processed by the evaluation units (known per se) of such waste water lifting systems for a pump control system.

According to another embodiment, one or more sensors are exchangeably fastened. This can be effected by simple snap-fastening or by using clamping connections and simplifies manufacture, while at the same time making a sensor easy to exchange in a possible service.

The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawing figures, in which:

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws