EP1531486A1

EP1531486A1 - On/off device particularly for submersible pumps

Info

Publication number: EP1531486A1
Application number: EP04026149A
Authority: EP
Inventors: Rubi Cegalin; Piero Zen
Original assignee: DAB Pumps SpA
Current assignee: DAB Pumps SpA
Priority date: 2003-11-14
Filing date: 2004-11-04
Publication date: 2005-05-18
Also published as: ITPD20030273A1; CN1616829A

Abstract

An on/off device particularly for submersible pumps, comprising, inside a dome (11), a microswitch (12) that is operated by way of a switching lever (13) arranged between the ends (14a, 14b) of a fork (14) that rotates rigidly with a rotation shaft (15) that is moved by a supporting rod (16), arranged externally to the dome (11), for a float (17), the on/off device further comprising, inside a containment shell (18), a monostable microswitch (12), in which the switching button (19) is available to the action of a cam-like lug (20) of the switching lever (13), the lever (13) being pivoted to a fulcrum (21) that is arranged inside the shell (18).

Description

The present invention relates to an on/off device particularly for submersible pumps.

Currently known submersible pumps have, inside a dome that closes them in an upper region, a bistable microswitch operated by means of a switching lever.

Said lever is arranged between the ends of a fork that is rotated rigidly together with a shaft that in turn is moved by a supporting rod, arranged externally with respect to the dome, for a float.

The lifting of the float, caused by the rise in the level of the liquid, generally domestic and industrial waste water, in which the pump is at least partially immersed, turns the shaft and the fork with it.

Such fork, by rotating, acts with a first end on the switching lever of the bistable switch, accordingly activating the pump.

As the liquid flows out due to the action of the pump, the float moves downward and the fork rotates in the opposite direction, until the second end of the fork acts on the lever, again switching the bistable microswitch so as to deactivate the pump.

An on/off device such as the one described, although being used extensively, has aspects that can be improved.

The bistable microswitch is generally fixed to the dome by means of two threaded elements, and its two contacts are tin-soldered to the electric power supply cables.

If, in an alternative setup of a similar pump, the float is arranged in a mirror-symmetrical position on the opposite side of the shaft around which it rotates with respect to the position of the basic setup, such alternative setup is very inconvenient to achieve.

It is in fact necessary to unsolder the soldered electric cables, unscrew the bistable microswitch from the dome, turn it over, screw back on the threaded fixing elements for fixing to the dome, and solder the electric cables again.

Moreover, the pump motor is usually at least partially resin-cast.

Due to overheating of the motor, the resin casting generates vapors that rise to the dome and deposit, by cooling, both on the contacts and on a spring steel bow that functionally connects the switching lever to the internal circuit of the bistable microswitch.

This deposit insulates the contacts at least partially and causes the microswitch to malfunction, hindering the correct snap motion of the spring steel bow.

The incorrect snap action of the bow can lead to early or late switching of the microswitch, with consequent malfunction of the pump and of the discharge system to which the pump belongs.

Moreover, the bistable microswitches used in known on/off devices are very expensive and are generally custom-made for the type of pump.

The aim of the present invention is to provide an on/off device particularly for submersible pumps that is capable of solving the drawbacks noted in known types.

Within this aim, an object of the present invention is to provide an on/off device particularly for submersible pumps that can be installed quickly and easily both in a pump in which the float is on one side of the rotating shaft and in a pump in which the float is arranged mirror-symmetrically on the opposite side.

Another object of the present invention is to provide an on/off device in which the contacts of the microswitch are well-protected against the vapors of the resin casting of the motor.

Another object of the present invention is to provide an on/off device that can be manufactured at low cost by also using standard components that are easily commercially available.

A further object of the present invention is to provide an on/off device whose performance is not lower, and whose reliability is higher, than known types.

A still further object of the present invention is to provide an on/off device particularly for submersible pumps that can be manufactured with known systems and technologies.

This aim and these and other objects that will become better apparent hereinafter are achieved by an on/off device particularly for submersible pumps, of the type that comprises, inside a dome, a microswitch that is operated by means of a switching lever arranged between the ends of a fork that rotates rigidly with a rotation shaft that is moved by a supporting rod, arranged externally to said dome, for a float, said device being characterized in that it comprises, inside a containment shell, a monostable microswitch in which the switching button is available to the action of a cam-like lug of said switching lever, said lever being pivoted to a fulcrum that is arranged inside said shell.

Advantageously, said lever has, proximate to said fulcrum and symmetrically with respect to the axis of said fulcrum, two protrusions with a cam-like profile for reversible snap engagement between two retention elements that are adapted to stabilize the configuration assumed by said cam-like lug.

Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a partially sectional side view of a pump equipped with an on/off device according to the invention;

Figure 2 is a front view of part of a device according to the invention in a first configuration;

Figure 3 is a front view of the same part as in Figure 2 of a device according to the invention in a second configuration;

Figure 4 is a view of another part of a device according to the invention;

Figure 5 is a perspective view of a device according to the invention.

With reference to the figures, an on/off device particularly for submersible pumps according to the invention is generally designated by the reference numeral 10.

The device 10 comprises, inside a dome 11 that constitutes the upper part of a submersible pump 60, a microswitch 12, which is operated by means of a switching lever 13 arranged between the ends, designated by the

reference numerals

14a and 14b respectively, of a fork 14.

The fork 14 rotates rigidly with a shaft 15, which is moved by a rod 16 that is arranged externally to the dome 11 and is designed to support a float 17.

The device 10 comprises, inside a containment shell 18, a microswitch 12 of the monostable type.

The switching button 19 is available to the action of a cam-like lug 20 of the switching lever 13.

The lever 13 is pivoted to a fulcrum 21 arranged inside the shell 18.

The lever 13 has two

protrusions

22a and 22b with a cam-like profile that are arranged proximate to the fulcrum 21 symmetrically with respect to the axis of the fulcrum.

The

protrusions

22a and 22b allow reversible snap engagement between two retention elements 23, which are adapted to stabilize the configuration assumed by the cam-like lug 20.

The retention elements 23 are formed by two bars, designated respectively by the

reference numerals

24a and 24b, which are elastically deformable and mutually opposite; their

free ends

25a and 25b each have a raised

portion

26a and 26b, which is shaped so as to engage reversibly the

corresponding protrusion

22a or 22b having a cam-like profile.

The containment shell 18 is constituted by two half-

shells

27a and 27b.

The two half-

shells

27a and 27b, as well as the lever 13, are conveniently obtained by molding plastic material.

The

bars

24a and 24b are monolithic with the first half-shell 27a and the fulcrum 21 is monolithic with the second half-shell 27b.

The shell 18 also has a stroke limiting abutment 28 for the lever 13 and two

openings

30a and 30b for accessing contacts 31 of the monostable microswitch 12.

The contacts 31 are of the type known commercially as Faston.

The monostable microswitch 12 has three male Faston contacts, designated by the

reference numerals

31a, 31b and 31c in the figures.

The monostable microswitch 12, of a standard and easily commercially available type, has intrinsic characteristics of waterproofness, compactness and low cost.

The monostable microswitch 12, of a commercially known type, and the shell 18 whose components are obtained by molding plastic material, allow the overall cost of the device 10 according to the invention to be far lower than the cost of conventional bistable microswitches.

Among the three male Faston contacts, there is an input contact 31a, a first output contact 31b, and a second output contact 31c.

Only one of the

output contacts

31b and 31c, in addition to the input contact 31a, is connected to a female Faston contact 80 so as to close the electric circuit, not shown for the sake of convenience, for activating the motor of the pump 60.

The lever 13, actuated by the

ends

14a and 14b of the fork 14, switches the circuit, closing it onto the output contact, for example 31b, that is connected to the female Faston contact 80, or opening it on the other output contact, for example 31c, that is free from the female Faston contact 80.

In the exemplified case, the lever 13 closes the circuit on the first contact 31b, releasing the switching button 19, as shown in Figure 2.

The pump 60 therefore is on when the button 19 is released and is off when the button 19 is pressed by the cam-like lug 20, as shown in Figures 1 and 3.

This solution allows to install the float 17 on the opposite side of the rotation shaft 15 with respect to the example of application described here, without having to remove and invert the device 10, as occurs in known devices, but simply by shifting the female Faston contact 80 from the first output contact 31b to the second free output contact 31c.

Installing the float 17 on the opposite side of the rotation shaft 15 with respect to the described example of application entails that the fork 14, when the float 17 rises, rotates in the opposite direction with respect to the described setup.

The pump 60, accordingly, must be on when the switching button 19 is pressed by the cam-like lug 20 and no longer when it is released as in the example described above.

This can be achieved easily, as mentioned, simply by moving the female Faston contact 80 from the first output contact 31b to the second free output contact 31c.

In view of the characteristics of the monostable microswitch 12 that is used, pressing the button 19 in fact connects the input contact 31a to the second output contact 31c, while releasing the button 19 connects the input contact 31a to the first output contact 31b.

The shell 18 is accommodated in a compartment 33 provided inside the dome 11.

The shell 18 is locked in the compartment 33 by an extraction-preventing cover 34.

The cover 34 is fixed to the dome by means of a threaded coupling that is not shown for the sake of simplicity.

The rotation shaft 15 is inserted in a through opening 35 that is provided with sealing gaskets 36 on a wall 37 of the dome 11.

The fork 14 is reversibly keyed on the shaft 15, on a first portion 15a thereof that is arranged inside the dome 11.

The rod 16 that supports the float 17 is instead keyed reversibly on a second portion 15b that is arranged outside the dome 11.

The internal end 15c of the shaft 15 is inserted in a hole 39 provided on a supporting plate 40 that is rigidly coupled to the dome 11, while the outer end 15d is accommodated in a recess 41 that is obtained on an extraction-preventing plate 42 for the rod 16.

The plate 42 is connected externally to the plate 11 by way of reversible fixing means 43.

The reversible fixing means 43 are constituted by two

plugs

43a and 43b, which are arranged symmetrically with respect to the axis of the shaft 15 and are forced reversibly into complementarily-

shaped pockets

44a and 44b that protrude from the dome 11 around the through opening 35.

Removal of the plate 42, which is also possible manually, allows a user to extract the rod 16 from its keying with the shaft 15 and to arrange it in a configuration at 180° with respect to the original described configuration.

In practice it has been found that the invention thus described solves the problems noted in conventional on/off devices particularly for submersible pumps.

In particular, the present invention provides an on/off device that can be manufactured at low cost also by using standard components that are easily commercially available.

Moreover, the present invention provides an on/off device particularly for submersible pumps in which a commercial-type monostable microswitch is integrated in a shell that is obtained at an extremely low cost by molding plastic material and is provided with simple mechanisms that make the device according to the invention operate like a bistable microswitch.

Moreover, the present invention provides an on/off device in which the contacts of the microswitch are well-protected against the vapors of the resin casting of the motor.

Moreover, the present invention provides an on/off device particularly for submersible pumps that can be installed quickly and easily both on a pump in which the float is on one side of the rotation shaft and on a pump in which the float is arranged mirror-symmetrically on the opposite side.

Moreover, the present invention provides an on/off device whose performance is not lower, and whose reliability is greater, than known types.

Moreover, the present invention provides an on/off device particularly for submersible pumps that can be manufactured with known systems and technologies.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

All the details may further be replaced with other technically equivalent elements.

In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art.

The disclosures in Italian Patent Application No. PD2003A000273 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

An on/off device particularly for submersible pumps, of the type that comprises, inside a dome (11), a microswitch (12) that is operated by means of a switching lever (13) arranged between the ends (14a, 14b) of a fork (14) that rotates rigidly with a rotation shaft (15) that is moved by a supporting rod (16), arranged externally to said dome (11), for a float (17), said device (10) being characterized in that it comprises, inside a containment shell (18), a monostable microswitch (12) in which the switching button (19) is available to the action of a cam-like lug (20) of said switching lever (13), said lever (13) being pivoted to a fulcrum (21) that is arranged inside said shell (18).
The device according to claim 1, characterized in that said lever (13) has two protrusions (22a, 22b) with a cam-like profile arranged proximate to said fulcrum (21) and symmetrically with respect to the axis of said fulcrum, for reversible snap engagement between two retention elements (23) that are adapted to stabilize the configuration assumed by said lug (20).
The device according to claim 2, characterized in that said retention elements (23) are provided by two mutually opposite elastically deformable bars (24a, 24b), the free ends (25a, 25b) of which each have a raised portion (26a, 26b) that is shaped so as to engage reversibly the corresponding protrusion of said two protrusions (22a, 22b) having a cam-like profile.
The device according to one or more of the preceding claims, characterized in that said containment shell (18) is constituted by two half-shells (27a, 27b), said bars (24a, 24b) and said fulcrum (21) being monolithic respectively with a first one (27b) and a second one (27a) of said two half-shells.
The device according to one or more of the preceding claims, characterized in that said shell (18) has a stroke limiting abutment (28) for said lever (13).
The device according to one or more of the preceding claims, characterized in that said shell (18) is provided with openings (30a, 30b) for accessing the contacts (31, 31a, 31b, 31c) of said monostable microswitch (12a).
The device according to claim 6, characterized in that said contacts (31, 31a, 31b, 31c) are of the type known commercially as Fasten.
The device according to one or more of the preceding claims, characterized in that said shell (18) is accommodated in a compartment (33) that is provided within said dome (11), and is locked in said compartment (33) by an extraction-preventing cover (34).
The device according to one or more of the preceding claims, characterized in that said rotation shaft (15) is inserted in a through opening (35) provided with sealing gaskets (36), on the wall (37) of said dome (11), said shaft (15) supporting said fork (14) and said rod (16) so that they are reversibly keyed respectively on a first portion (15a) thereof that is arranged inside said dome (11) and on a second portion (15b) thereof that is external to said dome (11).
The device according to claim 9, characterized in that the internal end (15c) of said shaft (15) is inserted in a hole (39) provided in a supporting plate (40) that is rigidly coupled to said dome (11), while the outer end (15d) is accommodated in a recess (41) provided in an extraction-preventing plate (42) for said rod (16), said plate (42) being connected externally to said dome (11) by way of reversible fixing means (43).
The device according to claim 10, characterized in that said reversible fixing means (43) are constituted by two plugs (43a, 43b), which are symmetrical and reversibly forced within complementarily shaped pockets (44a, 44b) that protrude from said dome (11) around said through opening (35).