The invention in the field of volume pumps relates to a rotary pump for liquid transportation and pressure generation.

A similar pump is known from e.g. the Author's Certificate No. SU 1320510 Al. The housing of the gear pump comprises a driving gear and a driven gear with corrected gearing in cylindrical hollows whereas the correction of teeth varies being cyclically repetitive, forming convex and concave zones on the radial surfaces of the gears. Unfortunately the productivity increase achieved by this method is not adequate and manufacturing such corrected gears proves to be complicated.

Also a hydromachine from the Author's Certificate No. SU 732574 is known, comprising a housing, suction and pressure apertures and two chambers separated by a partition and turned at the angle of 180° of each other. In the chambers of the hydromachine toothed blades comprising two parallel racks bound at the ends by half circles are located, whereas the diameter of the half circles equals to the diameter of the driving gear. Thereby the middle opening between the two parallel racks is of oblong shape. To maintain constant contact between the driving gear and the toothed blade an stationary shaft penetrates the middle openings of the toothed blades located in different chambers. Such technical solution facilitates carrying out additional movement. Thereby the pressure generated by the hydromachine is pulsating. Unfortunately such hydromachine is suitable only for fluids with good lubricating properties i.e. oils. Thereby the range of utilisation of the provided device is very limited. The rotary chambers create sealing problems and do not facilitate application of high pressures. Also manufacturing of such hydromachine proves to be complicated.

In practice also the pump (Utility Model No. EE 95 00034) is in use comprising housing with suction and outlet nozzles and rotors located on shafts mounted into the housing engaged by toothed belt. Such construction facilitates taking advantage of all the merits of classical gear pumps and to relevantly increase the productivity of the pump. The drawback of such solution is the rigid connection of one rotor of the pair of

oval rotors with the power source. In the given situation one of the rotors has to rotate at an unchanging angular velocity causing loss of balance between the rotors. While one of the rotors rotates at constant angular velocity the other is subjected to rhythmic changes of angular velocity. At the moments of angular velocity increase additional energy is required from the power source. This is followed by angular velocity decrease of the same rotor. As these movements are not simultaneous the energy released by decelerating movement creates vibration. Long period testing in actual working environment indicated that up to 50% of the energy necessary for utilising the pump was transferred into vibration processes.

The aim of the present invention is to design a pump in a manner providing widest possible range of utilisation, abolishment of vibration caused by the changing curve of the rotor surface and increase of productivity and efficiency of the pump.

The aim is achieved by locating at least two pairs of rotors in the pump housing separated by a partition and by turning the rotors in different chambers of the driving shaft by a certain angle from each other. By dividing the pump working chamber with a partition it is achieved that the pump shaft has in essence several rotors shifted at the angle of 180°/n of each other whereas n is the number of rotor pairs. By shifting the rotors by a certain angle a situation is created where the energy released by the rotor moving at decreasing angular velocity is used in the exact same amount and the exact same moment for the accelerating movement of the second rotor. Thereby balancing of the oval rotors is restored and the work of the pump becomes more uniform and economical.

In a utilised embodiment the rotors on the driven shaft may freely rotate regarding each other. As the angular velocities of rotors on the same shaft differ from each other such connection of rotors facilitates their unhindered rotation.

An example of the embodiment of the invention is provided on Figure 1 and is hereby described in more detail.

The rotary pump comprises the housing 1 with suction and outlet nozzles, oval rotors 3 located on shafts 2 engaged by toothed belt, and partition 4.

During work constant rotation of rotors 3 on shafts 2 takes place. The fluid between rotor 3 with oval toothed belt and pump housing 1 wall is alternatively pressed by the driving and driven rotors from suction side to outlet side. The partition 4 blocks the fluid pressing from between one rotor pair in between the other and thereby creates a separate chamber for each rotor pair. The rotors 3 remaining in such separate chambers are on the driving shaft turned by a certain angle from each other. In Figure 1 in the embodiment with one partition 4 the two rotors 3 on the driving shaft are shifted by 90° of each other. The energy released by the driven oval rotors decreasing angular velocity in one chamber is used simultaneously for the second rotors accelerating movement.

The necessary pressure and productivity are achieved by adding a suitable number of working chambers and utilising selected connection type (parallel or series). The described pump type does not need a bottom valve.