Prior art Small whirlpools and massage tubs achieve massaging effects either with warm water streams injected through jets arranged under the water level or by air bubbles pressed by a blower through holes in the bottom, or by a combination of both means, when the air is sucked by the ejection effect into a stream of warm water prior to its being introduced into the jet. Due to economic considerations the water in massage tubs is not always changed after each use, which requires rather intensive disinfection, the more so due to the threat of microbes proliferating in the piping that forms the technological part of a massage tub. During the recent years chemical disinfection has been partially or thoroughly replaced with the disinfecting effect of ozone that is created by an ozone generator within the stream of inlet air. The advantage of ozone consists in that it does not burden the bath water by disinfectants, while its adjusted presence in the water contributes to the therapeutical effect, especially in the case of varices and some skin diseases. Large numbers of whirlpools and massage tubs delivered without ozone generator are in operation.

The US patent 6,331, 279 B1 describes an apparatus for ozone generation whose enclosure accommodates an electrode and a high voltage transformer with means connecting the transformer with the electrode. Through an opening in the enclosure the air enters a separated part of the enclosure comprising the electrode and the ionised air leaves through the outlet into an air pipe wherefrom it is sucked into the water stream by the ejector in the water pipe. The US 6, 317, 903 B1 shows in Fig. 4 the electric wiring of the ozone generator, and namely of a similar type as described in US 6,331, 279, in the air branch of a therapeutic tub serving for the massage by bubbles of air enriched by ozone. Here the ozone generator is connected with the ejector in a bypass piping withdrawing air behind the blower and feeding the air enriched by ozone before the blower. The disadvantage of this described ozone generators resides in that they require rather complex connection with the air system of the massage tub. For ensuring the air stream passing through the generator they shall be either connected before the ejector or the blower should be before them. If a user of a current tub with bubble massage wishes to complement the air system by ozonisation using a subsequent installation of some known ozone generator, this entails rather excessive cost.

It is an aim of the present invention to substantially reduce the described drawbacks of known ozone generators and of their connection with the air duct.

Summary of the invention The above task is solved by an ozone generator, in particular for massage tubs consisting of a case with power supply accommodating a high voltage transformer coupled by means of cables with an ozone producing element-a discharge electrode or a UV discharge lamp-located in air stream, wherein the ozone producing element is accommodated in an air duct passing outside the case, the internal space of the duct being separated from the internal space of the case by a water-proof partition wall.

In a preferable embodiment allowing easy connection to the air system the case carries a T-shaped pipe fixed to it by its central branch that serves for the coupling to the air duct accommodating the ozone generator, the cables passing through the central branch of the form pipe provided with a waterproof partition wall.

The ozone generating element can be preferably a flat discharge electrode requiring minimum space and offering minimum resistance to streaming air.

The electrode can be created by a ceramic plate orientated in the sense of air stream and bearing metal plates of opposite poles on its opposite sides, the whole electrode being covered by a layer of silicate glass. This expands the electrode life substantially.

For improving the safety of users the generator can be provided with low voltage power supply.

Brief description of the drawings The invention will be further clarified by way of a drawing where Fig. 1 shows a preferable embodiment of the ozone generator in front view and Fig. 2 the same embodiment in lateral view.

Detailed description of the preferred embodiment The ozone generator according to Fig. 1 and 2 consists of case 1 provided with electric supply 2 with 12 V ac. The case accommodates a high voltage transformer coupled with cables and connectors with discharge electrode 3. The electrode 3 is located in a T-shaped pipe 4 connected with case 1, or it protrudes into the direct part of form pipe 4 intended for coupling to the air duct. A waterproof partition wall separates the interior of case 1 from the interior of form pipe 4. The electrode 3 consists of a ceramic plate orientated in the direction of air flow carrying metal plates of different polarity on its opposite sides, the whole electrode 3 being covered with a layer of silicate glass.

It is obvious that the principle of ozone generator according to the present invention will be applied also if the case will be replaced by moulding the transformer and the connecting cables to form a dielectric block attached to form pipe 4.

The benefits of the ozone generator according to the present invention will become apparent especially during additional installation on conventional technological equipment of a current massage tub: After having cut the existing air duct, both free ends will be glued into form pipe 4. If necessary, case 1 can be attached elsewhere, e. g. at the wall of the tub.