The present invention relates to a device for cleaning by suction especially suitable for internal cleaning of public transportation vehicles as buses, trains, ships and aero¬ planes or of large premises as schools, offices and hotels. It is previously known to use central suction devices for creating a suction effect at a number of working spots for connecting suction tools, but these have not been sufficient in view ot the difficult contamination to which public trans portation means and public premises are subjected. A special problem has been the removal of dirt which has got stuck by drying or has been tramped into mats and can not be removed by suction only.

A purpose of the invention is to improve a suction device of this type by a combination of steps for dissolving the dirt and increasing the suction force. This is schieved by spray¬ ing a liquid onto the suction spot, using a pump with a high vacuum as suction source and to provide the system with a tank for separating the suction air from dirt and liquid.

Closer features of the invention appear from the following specification which shows an embodiment of the invention illustrated in the annexed drawings showing:

Fig. 1 , a view of a suction device according to the inven¬ tion.

Fig. 2, detail picture on a larger scale of a suction head seen from below.

Figs. 3 - 5, details of the suction head seen along the arrows 3 - 3, 4.- 4 and 5 - 5 in Fig. 2.

The device shown in Fig. 1 comprises a suction system where the low pressure is generated by a vacuum pump 10, to which an inlet pipe 11 and an outlet pipe 12 are connected. The inlet pipe 11 is connected at its other end to a tank 13 via a separator 14 which prevents water and dirt from following with the air flow from the tank to the vacuum pump. The direction of the air flow is shown by the arrows 1 and 16.

Both the separator 14 and the tank 13 are provided with not illustrated level controls. The supply pipe to the tank ex¬ tends below the surface of the water 19 present in the tank. At the bottom of the tank dirt 20 gathers which has been brought along by the suction air. The water which also has been conveyed by the suction air mixes with the water in the tank. In this way the water which is added at the suction spot is prevented from reaching the vacuum pump 10. The tank 13 and the separator 14 cooperating therewith thus perform a separating function which is necessary for the use of a vacuum pump.

The pipe 18 is provided with an arbitrary number of connec¬ tion studs 21, of which one is shown in Fig. 1, each stud leading via a valve device 22 to a joining duct 23 to a con- nection for a hose 24, which leads to a suction tool 25 having a suction head 32. The arrow 26 shows the direction of the air current.

For the supply of water to the suction spot there is provi¬ ded a pipe 27 which suitably can be connected to an existing water supply system. It is suitable to use hot water. The water flows along the arrow 28 and continues in the pipe 29 via the valve device 22 parallel with the hose 23,24 to the suction head 32, where the water is sprinkled out through one or more spray nozzles. There can also be a not illust- rated dosing pump for a cleaning agent.

The hoses 24 and 29 are hung in a balance block 42 which holds the hoses weightlessly hung up in a curved loop, so that they can be pulled apart or pushed together, so that the hand tool 25 can be moved. At the upper end of the hand tool there is an operating lever 30 for opening or closing the air flow and another operating lever 31 for controlling the water flow. These levers act via the valve aggregate 22.

Fig. 2 is a view from below of a auction head 32. This con¬ sists of a frame 33 with an elongated hole 34 for the suc- tion air connected to the tubular hand tool 25 by a funnel 36 (Figs. 3 - 5). Along each long side of the frame 33 a

rubber strip 44 and 45 respectively is attached, which is formed with vertical ribs and is held by a clamping iron 46 and 47 respectively which is fastened to the frame 33 with screws 48. In order to prevent the rubber strips 44 and 45 from being compressed by the suction effect there are two sliding pins 52 arranged ^' , which have a rounded lower end surface in order to slide more easily on the floor. The rounded surface lies somewhat higher than the lower edge of the rubber strips 44 and 45. In order to prevent the head from getting stuck by the suction the strips 44 and 45 are separated from each other at their ends by openings 49.

The water is sprayed by a pipe 50 which is coupled to the hose 29 which is attached along the suction tool 25. The pip 50 is mounted on the suction head along one long side thereo and is provided with two spray nozzles 51, which sprinkle the water on the floor for instance in the form of a thin fan-shaped curtain from each nozzle.

The pump 10 shall be of a type which gives a substantial low pressure, for instance a vacuum pump which gives 80 % vacuum. A prerequisite for the use of such a pump is that the suction air is cleaned both from dirt and- from water, and this is achieved by means of the sludge tank 13 which is supported by the separator 14. Also other pumps giving a sub stantial low pressure are possible, for instance a turbine which gives about 60 # vacuum. The low pressure (vacuum) delivered by the pump should preferably be of the size 50 % vacuum or more.

The sprinkling of water does not only serve the purpose of dissolving the dirt, so that the dirt easier follows with the suction air. The water sprinkling in connection with the sludge tank has the advantage that ^' burning cigarrette stubs a?e • effectively extinguished and can be sucked into the system without danger of fire. This is not possible with dry suction systems where the risk of fire has been found so serious that the ash trays have to be emptied separately. Moreover the water serves to bind the dust.