Self-priming pumping device for hydraulic circuits

The pumping device comprises a pump driven by a motor having a stator and a permanent-magnet rotor located between polar expansions and connected to an impeller. A liquid suction duct and a liquid delivery duct are connected to the pump to define a hydraulic circuit. A reciprocating vacuum pump, for creating a negative pressure at the suction duct of the pump, has a resilient cylindrical element connected to a rigid cylindrical box-like element and defines therewith a chamber. The chamber has inlet and outlet valves connected to the hydraulic circuit through a poppet valve, and an arm-like member connected to the resilient element. An opposite end of the arm-like member supports a magnet located between poles of the stator of the motor, whereby to cause movement of the arm-like member and the resilient element for circulating fluid through the chamber via the inlet and outlet valves for priming the pump upon actuating the poppet valve.

BACKGROUND OF THE INVENTION 
The present invention relates to a pumping device for hydraulic circuits. 
The pumping device can be used particularly but not exclusively in external 
filters for aquariums. 
It is known that external filters for aquariums are constituted by a casing 
that contains filtering material, which retains the products that are 
suspended in the water of the aquarium. 
In order to filter the water, it is circulated in a closed circuit, to 
which the filter is connected in series under a water head. 
The head required for water circulation is provided by a pump accommodated 
in the lid of the filter. 
In order to prime the pump for the first time or after an operation for 
cleaning or replacing the filtering material, it is necessary to fill the 
body of the filter with water, so that the impeller is completely 
submerged. 
This is not a particularly easy or quick operation and also entails the 
danger of accidentally spilling water. 
Filters provided with self-priming devices, which allow to perform this 
operation directly, have recently been marketed. 
Although these filters avoid the usual awkward operations for filling the 
body of the filter with water drawn, from basins or other makeshift 
containers, by suction through the filter-tank return tube, they 
nonetheless have some limitations. 
A first embodiment provides a filter with a prechamber. The filter impeller 
is located in the prechamber, that is provided with a spillway or overflow 
system. 
The prechamber is filled by the user at pump startup with a cup of water, 
so as to completely submerge the impeller, which can thus be actuated and 
can produce a negative pressure inside the filter, whereby to draw water 
from the aquarium tank into the filter. 
The main limitation of this device is that after the first stages of the 
operation of the pump, the level of the water in the prechamber decreases, 
so that the impeller operates while it is only partially submerged and 
achieves full-section flow in the aquarium-filter tube only after a few 
minutes. 
For this reason, the operation of the pump is highly irregular during the 
first 10-15 minutes; in particular, there is a high noise level caused by 
the entrainment of air inside the pump delivery duct. 
A second solution provides a filter that has, at the delivery tube, an 
auxiliary membrane pump (rubber pear-shaped bulb), which when compressed 
manually by the user allows to produce a negative pressure that causes 
part of the water contained in the aquarium to flow into the filter. 
Although this system is rather effective, it is relatively awkward: in 
order to connect the auxiliary pump to the delivery tube it is necessary 
to lift the delivery tube from the tank, connect the suction of the 
auxiliary pump to said delivery tube, compress the auxiliary pump until 
priming is achieved, and then disconnect the auxiliary pump from the tube 
and immerse the end of said tube in the tank before the water reaches said 
end. 
SUMMARY OF THE INVENTION 
The aim of the present invention is to provide a self-priming, 
non-submersed hydraulic pumping device that eliminates the drawbacks 
mentioned above in known types. 
Within the scope of this aim, a consequent primary object is to provide a 
device in which self-priming is particularly quick. 
Another important object is to provide a hydraulic pumping device in which 
the pump operates in a regular fashion from the very beginning of its 
startup. 
Another important object is to provide a hydraulic pumping device in which 
priming can be activated in a particularly simple manner. 
Another object is to provide a device that is constructively simple and 
compact. 
Another object is to provide a device that prevents water loss. 
Another object is to provide a device that can be manufactured with 
conventional equipment and facilities. 
With this aim, these and other objects in view, there is provided a 
self-priming pumping device for hydraulic circuits, characterized in that 
it comprises a pump whose power plant is at least partially not submersed 
and a volumetric suction machine that is associated therewith and produces 
a negative pressure at the suction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the above figures, an external filter for aquariums is 
generally designated by the reference numeral 10 and comprises a hermetic 
container 11 that accommodates filtering masses 12 and is placed under a 
water head with respect to an aquarium 13; the inside of said container is 
connected to said aquarium respectively with a suction duct 14 and a 
delivery duct 15, thus forming a hydraulic circuit. 
A centrifugal pump 17 is accommodated inside the lid 16 of the container 11 
and has a synchronous motor 18 with permanent magnets; said motor 18 is 
constituted by a stator 19 with a metal lamination pack, with a winding 
that is not shown in the figures, and with polar expansions 21, between 
which there is a permanent-magnet rotor 22 that is connected to the 
impeller 23. 
A cylindrical body 24 is applied to the lid 16 for example by means of a 
bayonet coupling, not shown in the figures; a volumetric suction machine, 
generally designated by the reference numeral 25 and adapted to create a 
negative pressure at the suction of the pump 17, is fixed on the outer 
surface of said cylindrical body 24. 
The seat 26 of a poppet valve 27 is formed in the lower part of said 
cylindrical body 24; said valve is opened during priming to connect the 
suction duct 28 of the machine 25 to the inside of the filter 10 and is 
instead closed during the normal operation of said filter 10, to prevent 
water contained therein from rising back toward the volumetric machine 25. 
A pushbutton 29 is arranged on the upper part of the cylindrical body 24 
and is adapted to operate the priming system by pressing on the poppet 
valve 27. 
Indeed, by pressing said pushbutton 29, the locking system of the 
volumetric machine 25 is disengaged, as better explained hereinafter, and 
the poppet valve 27 is opened, whereas by releasing the pushbutton 29 
locking is engaged and the poppet valve 27 is closed. 
The pushbutton 29 can also be provided with a device for locking it in the 
inactive condition, constituted for example by a retractable pin, not 
shown in the figures, slideably connected to the cylindrical body 24 and 
releasably engageable in a seat formed in the pushbutton 29. 
The pushbutton 29 and the poppet valve 27 are provided with separate 
springs, respectively 30 and 31, which are accommodated in the cylindrical 
body 24 and are adapted to produce an elastic return of the pushbutton 29 
and the poppet valve 27. 
The poppet valve 27 is also equipped with a sealing ring of the O-ring type 
32a, which is associated with the shutter 27a, and is also equipped with a 
similar ring 32b on the body. 
Said volumetric suction machine 25 includes a resilient member, such as a 
cylindrical rubber element 33a that forms a chamber 33 and defines an open 
end at one of its flat faces; the open end of said cylindrical element 33a 
is inserted on a rigid cylindrical box-like element 34 so that a wall 35 
that lies inside the element 34 constitutes the lower flat face of said 
chamber 33 (which thus acts alternatively as a suction chamber and as a 
delivery chamber). 
A suction port 36 and a delivery port 37 are formed in the wall 35, and 
each port is provided with a one-way or non-return membrane valve, 
respectively 38 and 39. 
The valves 38 and 39 are connected to the wall of the rigid box-like 
element 34. 
The suction port 36 is connected, by means of the duct 28, to the seat of 
the spring 31 of the poppet valve 27. 
The opening of the poppet valve 27 therefore connects the inside of the 
filter 10 to the suction of the volumetric machine 25. 
The operation of the volumetric machine 25 arises from the variation in the 
volume of the rubber chamber 33 that is generated by the oscillation of a 
lamina or arm-like member 41, rigidly coupled in a cantilevered fashion 
over the center of said chamber. 
The lamina 41 is made to oscillate by the action of the magnetic flux that 
is produced by the motor 18 on a magnet 42 fixed to the free end of the 
lamina 41 and arranged between the poles 21 of the stator 19. 
When the chamber 33 is extended, the air is drawn in through the suction 
duct and enters said chamber (the intake valve allows the air to enter but 
not to exit from said duct); when the chamber 33 is compressed, the air is 
pushed through the discharge valve into the delivery duct and is 
discharged outside the filter, thus defining a reciprocating vacuum pump. 
A hook 29a is fixed to the button 29 and, when inactive, partially 
surrounds the lamina 41 and locks it; when the hook 29a is moved by 
pressing on the pushbutton 29, it allows said lamina to move freely. 
Therefore, when the motor 18 and accordingly the pump 17 are switched on, 
after the release of the hook 29a connected to the pushbutton 29, the 
magnet 42 starts to vibrate, activating the volumetric machine 25 as well. 
By pressing the pushbutton 29 further, the machine 25 is connected to the 
suction inlet of the pump 17, which is placed under a negative pressure, 
drawing water from the aquarium 13 and performing priming. 
In practice it has been observed that the intended aim and objects of the 
present invention have been achieved, providing a self-priming 
non-submersed hydraulic pumping device that permits particularly easy pump 
priming achieved by means of the simple pressing of a pushbutton. 
Priming is also particularly quick, since in less than ten seconds a 
full-section flow is produced in the suction duct of the pump, allowing to 
fill the filter quickly. 
The pump therefore operates in a regular fashion from the very beginning. 
The fact that the volumetric machine associated with the pump is not 
actuated by a specifically provided motor, but by the same motor as the 
pump, thus allowing the device to be particularly simple from a 
constructive point of view. 
The compact size of the device and the fact that all components thereof are 
contained inside the lid of the filter should also be stressed. 
One should also note its extreme safety in operation, since the two 
automatic return springs 30 and 31 ensure the disengagement of the machine 
25 and the closure of the poppet valve 27 once priming has occurred. 
Finally, the fact that the safety device prevents water losses from the 
filter 10 caused by accidental pressing of the pushbutton 29 should also 
be noted. 
The invention thus conceived is susceptible of numerous modifications and 
variations, all of which are within the scope of the inventive concept. 
All the details may furthermore be replaced with other technically 
equivalent elements. 
The device may of course also be provided for use in pumping operations 
different from those in aquariums, in any application in which a 
non-submersed pump is present. 
In practice, the materials employed, so long as they are compatible with 
the contingent use, as well as the dimensions, may be any according to the 
requirements.