Filter device, particularly for aquariums

The filter device comprises a filter chamber, a water supply chamber associated with the filter chamber and an aspiration tube, having a first and inserted in the water supply chamber and a second end which is immersable in an aquarium. The device also comprises a centrifugal pump adapted for feeding water to the filter chamber, and an impeller housed in an impeller chamber having an aspiration port, whereon the first end of the aspiration tube is selectively positionable. The impeller is associated with a permanent magnet rotor contained in a watertight cylindrical body, externally embraced by a cluster of stator windings. The filter chamber has a water outlet and houses a container adapted for accommodating filter elements.

BACKGROUND OF THE INVENTION 
The present invention relates to a filter device, particularly for 
aquariums. 
More in particular, the object of the invention is a filter device of the 
type which is hooked onto the upper edge of an aquarium so as to draw, 
with the aspiration tube, inside the tank and so as to also have the 
discharge outlet in the tank. 
The filter body instead remains outside the tank so that the electric parts 
are not wet by the water. 
Usually, filter of this type are rather complicated and expensive, since 
they are composed of many parts. 
Moreover, in the case of filters with variable flow rate, this variation is 
achieved simply by reducing, by means of a cutoff means, the cross section 
of the aspiration tube. 
SUMMARY OF THE INVENTION 
Accordingly, the main aim of the invention is to provide a filter for 
aquariums with variable flow rate, which overcomes all of the 
inconveniences encountered in the known types of filters for aquariums. 
Within the above-cited aim, an object of the present invention is to devise 
a filter for aquariums with adjustment of the flow rate, which is composed 
of a reduced number of parts which can be easily assembled. 
A further object is to provide a filter in which the adjustment of the flow 
rate is particularly simple, and achieved without flow cut-off devices in 
the aspiration tube. 
Still another object is to provide a filter wherein it is simple, by virtue 
of its structure, to replace the filter means. 
This aim, as well as this and other objects which will become apparent 
hereinafter, are achieved by a filter device, particularly for aquariums, 
characterized in that it comprises a filter chamber associated with a 
water supply chamber, a first end of an aspiration tube being inserted in 
said water supply chamber, a second end of said aspiration tube being 
immersable in an aquarium, said first end being positionable over the 
aspiration port of a chamber of an impeller of a centrifugal pump, adapted 
for feeding said filter chamber, said impeller being associated with a 
permanent-magnet rotor contained in a watertight body, externally embraced 
by a cluster of stator windings, in said filter chamber there being 
provided at least one water outlet, there being inserted a bored container 
adapted for accommodating filtering means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the above described figures, the filter device according 
to the invention is composed of a filter chamber 1, substantially in the 
shape of a parallelepiped, to the side whereof is arranged a second, 
smaller, water supply chamber 2 which is downwardly provided with a 
cylindrical connection 3 which advantageously has a wide-pitch thread 4 in 
its interior which in practice extends through approximately 90.degree., 
on which, after a sealing ring 5 has been inserted, a sealed or watertight 
cylindrical body 6 is screwed, on said body there being mounted, 
externally and by simple interference, the cluster of the stator windings 
7. 
Inside said cylindrical watertight body 6, and arranged substantially 
axially with respect thereto, is a shaft 8, which is expediently made of 
metal and downwardly fixed by being force-fitted into a recess 9 provided 
in a projection 10 of the same body 6. 
On said shaft 8, is fitted the permanent magnet rotor 11 which, in its 
upper part, has a cylindrical region 12, having a reduced diameter, which, 
proximate to its end, is provided with a toroidal projection 13 which, as 
will be explained hereinafter, is adapted for preventing axial movement of 
the impeller 14 with respect to the rotor 11. 
Said impeller 14 has a plurality of radial blades 15 associated with a 
hollow cylindrical body 16, which is internally provided with a toroidal 
recess 17, adapted for engagement with said toroidal projection 13 so that 
the impeller is retained axially while being freely rotatable with respect 
to the body of the rotor 11. 
Said impeller 14 is furthermore provided with a small tab 18, arranged 
along an outer generatrix of the cylindrical body 16, extending beyond the 
length of the body 16 on the opposite side with respect to the blades 15, 
and adapted for interacting with a lug 19 rigidly associated with the 
cylindrical region 12 of the rotor 11 and arranged along an external 
generatrix thereof. 
In practice, upon starting the rotor 11, the lug 19 engages with the tab 18 
of the impeller 14, thus entraining and imparting motion to the impeller 
14. 
Said impeller 14 is contained within a chamber 20 which is obtained by 
interposing in the supply chamber 2 a sector 21, having formed therein a 
circular hole or port 22, the center of which is coincident with the 
geometric axis of the impeller 14. 
To supply this region with water, an aspiration tube 23 is provided, which 
is advantageously shaped like an upturned U, a first end 24 whereof, has a 
cross section substantially corresponding to the hole 22, and is 
positioned in front of the same hole 22, while the second end 25, provided 
with first filtering means 26, is arranged for drawing water from the 
aquarium or tank. 
The tube 23 is connected to the filter chamber 1 by means of elastic 
engagement means 27, adapted for allowing rotation of the tube itself 
about a geometric axis 28 which is coincident with the longitudinal axis 
of the portion of tube which draws or aspirates water from the aquarium. 
In this manner it is possible to rotate the tube 23 by an angle 29, so that 
the position of the first end 24 of the tube 23 can be varied with respect 
to the hole 22 formed in the sector 21 of the impeller chamber 20. 
Thus, if the end 24 of the tube 23 is positioned such that it exactly 
overlaps the hole 22, the maximum flow rate of water will be achieved, 
since there will be a complete aspiration only through the tube 23. 
If instead, as indicated in FIG. 4, the tube is moved by a desired angle, 
only part of it will be facing the hole 22, thus reducing the amount of 
water which is aspirated from the aquarium or tank, and taking in more 
water instead, from the supply chamber 2, as indicated by the arrows 30 
(FIG. 4). 
The impeller 14, which is of the centrifugal type, pushes the aspirated 
water into an outer annular chamber 31, which is completely open and in 
communication with the lower part 32 of said filter chamber 1. 
Within said filter chamber 1, a container 33 is provided which has bored 
lateral walls 34 and 35, and a bored bottom 36. 
Within said container 33, filtering masses 37 are contained which have the 
purpose of retaining the impurities carried by the water. 
Said container is upwardly provided with two tabs 38 which have holes 39 to 
allow their easy grip during extraction. 
The filter is completed by an upper closure or lid 40, wherein a slot 41 is 
formed, through which a control dowel 42 projects which is rigidly 
associated with the tube 23, the setting of the position of the tube with 
respect to the inlet of the impeller chamber 20 being possible by acting 
on said dowel, thus determining the flow rate of the pump. 
It should be noted that the two chambers, i.e.; the filtering chamber 1 and 
the supply chamber 2, are hydraulically connected not only through the 
discharge path of the pump but also through the holes in the wall 35 of 
the container 33. 
In this manner, when the inlet of the water which originates directly from 
the tank of the aquarium is partially cut-off or throttled, there is a 
continuous recirculation of the water contained in the filter, which is 
thus filtered many times before it is returned into the tank of the 
aquarium. 
In the upper part, said filtering chamber 1 is provided with a discharge 
outlet 43 which projects with respect to the body of the filtering chamber 
1 so as to be located, after assembly, inside the aquarium. 
The entire assembly, composed of the two chambers, is advantageously 
provided monolithically by injection of plastic material in a die. 
Among the advantages of the structure thus composed, there is the 
simplicity of manufacture of the motor-pump assembly, as well as the 
reliable watertightness achieved, which is of a static type, since no 
rotatable seal is provided, it being thus impossible for the water to be 
able to affect the electrically powered parts of the stator winding 
cluster. 
The assembly is effected by simply inserting and rotating the cylindrical 
body 6 within the cylindrical connection 3. 
A second advantage is the constructive simplicity with which a flow rate 
adjustment has been achieved which, though it partially cuts off or 
throttles the incoming water, does not throttle the pump, which keeps on 
recycling and therefore filtering the water contained in the filter 
chamber and in the supply chamber. 
A further factor of simplicity derives from the container, which allows an 
easy extraction of the filtering masses which can thus be either cleaned 
or replaced. 
The structure of the filter which derives therefrom is expediently composed 
of a small number of parts assembled to one another in a non-critical 
manner without chemical or mechanical fixing means. 
The entire assembly is thus particularly advantageous both from the point 
of view of construction and from the point of view of use. 
Naturally, the materials employed and the dimensions may be any according 
to the amount of water to be treated and therefore according to the 
capacity of the aquarium for which the filter is intended.