EP1233188A1

EP1233188A1 - Level-dependent pump control

Info

Publication number: EP1233188A1
Application number: EP01830104A
Authority: EP
Inventors: Massimo Landini
Original assignee: Starite SpA
Current assignee: Starite SpA
Priority date: 2001-02-16
Filing date: 2001-02-16
Publication date: 2002-08-21

Abstract

A floating control device present in a pump suitable for being immersed in a reservoir wherein a liquid<is present comprising: a float (14) oscillating between a first and a second position; a switch (10) of an electrical circuit associated to the float (14), suitable for opening the circuit when the float (14) is in the first position and to closing it when the float (14) is in the second position; a chamber (15) containing the float (14) suitable for being flooded from liquid; an inlet mouth (19) and an outlet mouth (18) for the liquid into and from the chamber (15); means for setting in the chamber (15) a flow of liquid between the inlet mouth (19) and the outlet mouth (18) that keeps the float (14) in the second position when the liquid decreases below a surface level lower than the float (14) up to a minimum surface level in the reservoir. The device has the advantages of allowing a reduction of the reservoir containing the liquid with respect to other pumps with float inside, since the level gap between the top zone where the float is present and the base of the pump is about the same height as the pump. Furthermore, simple installation, reduction of the assembling costs with respect to systems with float both inner that outer, protection against possible jamming of the float are possible.

Description

Field of the invention

The present invention relates to a float control device for drainage electropumps and similar apparatus.
Furthermore the invention relates to drainage electropumps that use such a device.

Background of the invention

For emptying a drain well or a reservoir, normally an electropump is used controlled by a floating switch, located outside the same.
In a first type of pumps the float is connected to the pump by means of a stiff arm. When the surface level of the liquid of the drain well rises over the maximum height of the pump, the rise of the float causes the arm to rotate turning on an inner switch that starts the pump. The pump then empties the well and the float, when lowering, opens the inner switch stopping it.
This solution needs a usable space remarkably higher than the encumbrance of the pump, owing to the swinging movement of the float. The encumbrance of the pump has the drawback that when drowning the pump the float may hit against the walls of the well, as well as against ducts or other devices. Furthermore the movement of the float can get jammed owing to dirt, leaves, debris, vegetation. This requires frequent inspections and a risk in any case of a faulty dryout pump operation or a missed start when the surface level of the water rises is always present.
For certain types of pumps, an electrical flexible insulated cable connects the float to the pump and in the float there is a gravity switch. This allows much more agility to the float and a slightly minor encumbrance, but it does not eliminate the other problems above described. The float with the switch and the cable, furthermore requires a full insulation from humidity and involves a higher cost of the pump.
Furthermore pumps exist with float arranged inside connected by means of an arm switch or a flexible cable switch. They, however, involve a remarkably higher encumbrance of the body containing the pump, a rather complex mechanics and a differential level between the minimum surface level and the maximum quite less than the height of the pump. A low differential causes the need of drain wells of wide diameter, for avoiding too short operation cycles.

Summary of the invention

It is an object of the present invention to provide a float control device, for example, even if not exclusively, for drainage electropumps, which is in the body of the pump but that has a differential of minimum/maximum surface level about the same height as the pump.
It is also object of the present invention to provide a pump with inner float control device that allows a simple installation, a reduction of the assembling costs and a protection against possible jamming of the float.
These objects are reached by the float control device according to the present invention, the device being inserted in a pump suitable for being immersed in a reservoir wherein liquid is present, whose characteristic is that it comprises:

a float oscillating between a first and a second position;
a switch of an electrical circuit associated to the float, suitable for opening the circuit when it is in the first position and for closing it when it is in the second position;
a chamber containing the float suitable for being flooded from liquid;
an inlet mouth and an outlet mouth for the liquid into and from the chamber;
means for setting a flow of liquid in the chamber between the inlet mouth and the outlet mouth that keeps the float in the second position when the liquid decreases below a surface level lower than the float up to a minimum surface level in the reservoir.

According to another aspect of the invention, a submersed pump has the characteristic that it comprises:

a float oscillating between a first and a second position;
a switch of an electrical circuit associated to the float, suitable for opening the circuit when it is in the first position and to closing it when it is in the second position;
a chamber containing the float suitable for being flooded from liquid;
an inlet mouth and an outlet mouth for the liquid into and from the chamber;
means for setting a flow of liquid in the chamber between the inlet mouth and the outlet mouth that keeps the float in the second position when the liquid passes a minimum surface level in the reservoir.

The pump comprises a delivery section of the liquid, the chamber with the float being preferably located near the delivery section, the inlet mouth bringing into communication the delivery section with the chamber.

Brief description of the drawings

Further characteristics and the advantages of the method according to the present invention will be made clearer with the following description of an embodiment thereof, exemplifying but not limitative, with reference to the attached drawings, wherein:

figure 1 shows a diagrammatical cross sectional view according to a vertical plane of a pump in which a float control device is mounted according to the invention;
figure 2 shows a cross sectional view according to a vertical plane of a pump in which a float control device according to the invention is provided;
figures 2A-2C show three different steps of operation of the pump of figure 2 according to the surface level of the liquid;
figures 3A-3C show a cross sectional view according to a vertical plane of a different embodiment of the pump of figure 2 in three different steps of operation according to the surface level of the liquid.

Description of a preferred embodiment

With reference to figure 1, a submersed pump 1 for liquids comprises a body 2 suitable for resting on a surface 3, for example the bottom of a sink or a drain well, with vertical axis 4.
The body 2 has at the base a suction section 5 for the water, that an impeller 7 sucks through a diffuser 6 and primes to a delivery section 8. Impeller 7 is operated by a electric motor 9.
The pump is therefore operated by impeller 7, which has helical blades priming centrifugally the liquid towards delivery section 8 and sucking in the meantime other liquid that passes through suction section 5 and diffuser 6.
According to the present invention, a switch 10 is provided that turns off or on an electrical circuit that operates motor 9. When impeller 7 is still, the liquid can enter freely in the body 2 of the pump and rise, flooding it, except from room 11 wherein the motor 9 and the switch 10 are housed. Room 11 is a dry zone not reached by the water, which instead floods wet spaces 12, from the edge of delivery section 8, and 13, in communication with suction section 5.
In the upper zone of wet space 13 a small float 14 is located suitable for measuring the surface level of the liquid that floods the pump, corresponding for example to the surface level in the drain well. Float 14 is housed in a chamber 15 made in the top part of the pump body 2 and located between the suction section 5 and the delivery sections 6 and 8 of the same.
To float 14 a small magnet 16 is associated located close to the wall between wet chamber 15 and dry motor room 11, where microswitch 10 is located for operating the motor 9. Microswitch 10 has an actuating lever 17 in which a magnet is located that follows for magnet coupling the movement of magnet 16 of float 14 when the latter moves.
Chamber 15, as above said, is separated from the suction section 6 and from delivery section 8, even if it communicates with them. More precisely, chamber 15 is in communication with the suction section 6 of the pump by means of a small outlet hole 18. The delivery section of the pump is also communicating with chamber 15 through a inlet hole 19 of diameter higher than hole 18.
When the surface level of the liquid rises, flowing through the opening at base 5, the liquid floods chamber 15 causing float 14 to rise. This movement, through the coupling of permanent magnets 16-17, operates microswitch 10 causing the pump to run.
A small amount of the liquid flowing in delivery section 8 recirculates through holes 18 and 19, into chamber 15 with float 14, keeping float 14 up as long as there is liquid to prime, even if the surface level 20 of the liquid outside the pump is lower than the float .
Float 14 comes back to the original position only when the pump delivery flow stops about completely, for absence of liquid.
With reference also to figures 2A-2C, which relate to a pump substantially similar to that of figure 1, the operative steps of the device according to the invention are the following (figure 2A-2C):

liquid 20 reaches the hole of communication of chamber 15 in which float 14 is present;
float 14, rising, starts motor 9 of the pump that primes liquid to delivery section 8;
through hole 18 a part of the liquid primed to the delivery section flows continuously into chamber 15 with float 14 and exits from hole 19, through a duct 21 that is in communication with the suction section;
The surface level 20 of the liquid decreases under float 14, the recirculation flow rate is in any case sufficient to keep float 14 up;
the surface level of the liquid reaches the base 5 of the pump and the recirculation flow rate is not sufficient any more to keep up the float 14 that while lowering stops the pump;
chamber 15 is emptied and the pump starts again only after that the surface level 20 of the liquid reaches again float 14 (figure 2B).

The advantages of the device according to the invention are the following:

reduction of the reservoir containing the liquid with respect to other pumps having a float inside, since the level gap between the top zone wherein the float is arranged and the base of the pump is about the same height as the pump;
simple installation;
reduction of the assembling costs, with respect to systems with both float inside and outside;
protection against possible jamming of the float.

With reference to figures 3A-3C, a possible different embodiment of the device according to the invention provides a controlled minimum emptying system (Figure 3A-3C).
The outlet hole 18 of chamber 15 with float 14 is enlarged in order to have the same dimensions of inlet hole 19, and in duct 21 a small floating valve 23 is inserted at a height predetermined according to the minimum surface level 20 of liquid that has to be guaranteed.
In a way similar to the case previously described, when, starting from the position of figure 3A, the surface level 20 of the liquid reaches and passes float 14 (figure 3B), the pump starts. The liquid floods chamber 15 also when the surface level 20 decreases under the float (figure 3C), owing to the recirculation flow of liquid that valve 23, even if closed, does not block. When, however, the surface level 20 of the liquid decreases under valve 23 (figure 3A), opening it, the recirculation flow is not sufficient any more to keep up the float 14 that while lowering stops the pump. Chamber 15 is emptied. The pump starts again only after that the surface level 20 of the liquid reaches float 14 (figure 3B).
The recirculation flow is in any case necessary because the floating valve would affect the surface level control, owing to leaks of water that would slowly empty the chamber.
The foregoing description of a specific embodiment will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

A float control device present in a pump suitable for being immersed in a reservoir wherein liquid is present, characterised in that it comprises:

a float (14) oscillating between a first and a second position;

a switch (10) of an electrical circuit associated to said float (14), suitable for opening said circuit when said float (14) is in said first position and for closing it when said float (14) is in said second position;

a chamber (15) containing said float (14) suitable for being flooded from liquid;

an inlet mouth (19) and an outlet mouth (18) of liquid from said chamber (15);

means for setting in said chamber (15) a flow of liquid between said inlet mouth (19) and said outlet mouth (18) that keeps said float (14) in said second position when said liquid decreases below a surface level lower than said float (14) up to a minimum surface level in said reservoir.
Device according to claim 1, wherein the outlet mouth (18) of said chamber (15) has a cross section smaller than said inlet mouth (19).
Device according to claim 1, wherein the outlet mouth (18) of said chamber (15) is connected to a duct (21) which, at a surface level below said float (14), has a floating valve.
A submersed pump characterised in that it comprises the device according to the previous claims.
Pump according to claim 4, comprising a suction section and a delivery section, wherein the inlet mouth (19) of said chamber (15) is in communication with said delivery section and the outlet mouth (18) of said chamber (15) is in communication with said suction section, said outlet mouth (18) being of cross section smaller than said inlet mouth (19).
Pump according to claim 4, comprising a suction section and a delivery section, wherein the inlet mouth (19) of said chamber (15) is in communication with said delivery section and the outlet mouth (18) of said chamber (15) is in communication with said suction section, said outlet mouth (18) being provided with a floating valve.