EP0512937A1

EP0512937A1 - Improvements to pressurestats

Info

Publication number: EP0512937A1
Application number: EP92500048A
Authority: EP
Inventors: Jose Ignacio Bilbao Mancisidor
Original assignee: Fagor Electrodomesticos SCL
Current assignee: Fagor Electrodomesticos SCL
Priority date: 1991-05-07
Filing date: 1992-04-29
Publication date: 1992-11-11

Abstract

One of the improvements comprises providing two ducts (16-17/21-22) communicating the drum whose water level is to be controlled and the pressure chamber (4) in the pressurestat, the said ducts having respective nozzles or restrictors (18/23) in order to minimise the risk of the intercommunication between the pressure chamber (4) and the washing drum from being blocked.

The second improvement, namely preventing the operation of the machine in the event of a given default, comprises providing a safety pressurestat in which the release spring (14) opposed by the membrane (3) is scaled such that its tension is not enough to reset the pressurestat when the latter is triggered due to abnormal excessive pressure in its chamber (4) caused by the said breakdown, which release spring (14) is supported by a push-button (24) which must be manually pressed in order for the machine to recover the operating position, which will only be done by the servicing expert once the fault is put right.

Description

OBJECT OF THE INVENTION

The present invention relates to a number of improvements to pressurestats, namely pressurestats used in household appliances such as clothes and dish washing machines, and which are in actual fact pressure driven electric switches, such improvements being designed to enhance the operation of this kind of machines thereby to avoid certain defaults therein and preventing that when confronted with other breakdowns as we shall see hereinafter the machines will continue to function nonstop throughout unoperative or unnecessary cycles, which only lead to a useless consumption of power and water.

BACKGROUND OF THE INVENTION

In machines of the above kind, that is clothes and dish washing machines, besides the provision of timer-switches which determine specific working cycles, there are a number of functions that cannot be time-controlled, given the involvement of factors external to the machine, for instance filling of the washing drum which shall be more or less time consuming depending on the mains pressure, the cleanliness of the filters and so forth, and hence naturally for these purposes means controlling the water level in the drum are resorted to.
The use of pressurestats to such end has long since been known, for instance as described in utility model 196,844, where the pressurestat itself defines two chambers divided by an elastic membrane, one being a pressure chamber and the other an electrical switching chamber, the pressure chamber being in this case located above the filling level within the drum and related to the latter by means of a system of comunicating vessels, such that as the level in the washing drum rises, the elastic membrane is gradually stretched, and a pusher attached thereto acts upon the switch mechanism.
This switch device is fitted with an elastic sheet, one of the latter's ends being attached to one of the connecting terminals and provided at the opposite end with a double position connection, one in which it closes the circuit supplying the drum's electric filling valve and another in which whilst cutting out the supply to the electric valve it brings about the closure of the circuit feeding the water heater resistors, switching suddenly from one position to the other, to minimise breaking currents, because the said elastic sheet is provided with a die-cut tab upon which the electric valve pusher acts, the free end of which communicates with the actual elastic sheet through a trigger spring which defines two stable end positions for the repeatedly mentioned elastic sheet, corresponding with the aforesaid connections, and an unstable middle position of equilibrium at which the elastic sheet and the connection tab are coplanar.
With this basic construction and in order for the pressurestat not to be affected by the air pressure fluctuations caused by stirring and turbulence produced within the drum when at work, the air duct into the pressurestat's pressure chamber is provided with a nozzle of small diameter which in practice poses problems arising from the contingent blockage of such nozzle by left-over detergent accumulating from the washing drum, left-over talcum from stripping the plastic joining pipe, by loose threads detached from the clothes or otherwise.
Furthermore, in this kind of pressurestats, such as the aforesaid utility model 196,844, the said connection tab is fitted with a spring acting against the membrane so that when the pressure exerted by the said membrane drops, due to a lower water level in the washing drum, the pressurestat resets automatically going back to the starting position where the supply to the heater resistors is cut off and the electric valve is again supplied for the drum to be filled once again.
This means that in the event of the washing machine breaking down, for instance due to defaults in the supply of water or level control, the washing machine can work endlessly or incorrectly, taking in water, heating and expelling the same, refilling the drum and endlessly repeating this cycle until the user realises that a problem exists and turns off the machine by means of the general switch, which can be after a considerable space of time has elapsed and hence after power has been used up to no avail and the machine has been worn out.
The above problem is in both respects applicable to both simple pressurestats, as in utility model 196,844 and multiple pressurestats, as described in utility model 194,050, and in those with independent pressure chambers, thereby allowing different machine pressures or different functions thereof to be controlled.

DESCRIPTION OF THE INVENTION

The improvements subject of the invention fully solve the above problems in any kind of pressurestats.
More specifically and in order to achieve the above, one of the improvements set forth comprises providing two independent inlets to the pressurestat's pressure chamber, which can in turn be done in two different ways, either modifying the actual pressurestat's body, providing the aforesaid two inlets directly in the same, or retaining the structural characteristics of the pressurestat's body, with the sole exception that the nozzle or restrictor in the sole duct entering the same is enlarged until the risk of obstructions at that point is entirely eliminated, an adopted item being attached to the said duct carrying the aforesaid two ducts and wherein the relevant nozzles are provided, such that a possible blockage would affect only one of them, the other one remaining operative.
The other improvement subject of the invention comprises providing the pressurestat membrane release spring at one of the chambers thereof, which could be called safety chamber or pressurestat, with scaling control means such that when the working pressure matches the faulty working pressure, which is usually excessive, this safety chamber or pressurestat will send out a cut-off signal causing the machine to stop without being able to continue working, inasmuch as the pressure in the said spring will not be sufficient to reset the same.
More specifically, this release spring rests upon a push-button such that when the assembly is at rest, the said spring is unable to casue the pressurestat to be reset, whereas when the said push-button is manually pressed, which the expert servicing the machine can do, the said spring is loaded and causes the required resetting, which will naturally be once the fault causing the said safety pressurestat to work has been put right.

DESCRIPTION OF THE DRAWINGS

In order to provide a fuller description and contribute to the complete understanding of the characteristics of this invention, a set of drawings is attached to the specification which, while purely illustrative and not fully comprehensive, shows the following:
Figure 1.- Is a diagrammatic side elevation and part sectional view of a multiple pressurestat provided with the first of the improvements subject of the invention.
Figure 2.- Is a view similar to figure one, but of a simple pressurestat.
Figure 3.- Is a more detailed view of a pressurestat as in figure 2, similarly constructed in accordance with the first improvement subject of the invention, but with respect to a practical embodiment of the said improvement, and in which the second improvement is also provided, regarding the pressurestat reset button, which is also shown in detail to a larger scale and as a cross-section.
Figure 4.- Is a side elevation and quarter-sectional view of an adopted item for the provision of two independent ducts, replacing that of figure 3 and designed to be attached to the edge or periphery of the pressurestat.
Figure 5.- Is the item of the above figure, at 90° and also as a quarter-sectional view.
Figure 6.- Is a view similar to that of figure 4 of another adopted item designed in this case for pressurestats provided with a pressure inlet at their base.
Figure 7.- Is, finally, the adopted item of figure 6 at 90° and also shown as a quarter-section.

PREFERRED EMBODIMENT OF THE INVENTION

In light of these figures and more specifically figure 3, it can be seen that the improvements subject hereof are applicable to pressurestats in which a base body (1) and a cover (2) are defined, duly clamped by fitting a membrane (3) between their mouthpieces defining therein a pressure chamber (4) and a mechanisms chamber (5), which mechanisms are actually an elastic sheet (6) attached through one of its ends to the input terminals (7) and provided at its free end with a terminal (8) which can alternately close the circuit with two connections (9) and (10), the first of which is provided for the pump supplying water to the washing drum and the second for the heater electric resistors thereof, the membrane (3) indirectly acting upon this elastic sheet (6) specifically with the assistance of a pusher (11) which acts upon a tab (12) defined within the actual sheet (6) and the free end of which is connected to the latter by means of a trigger spring (13) which assures a sudden positional change of the elastic sheet (6) and hence minimum wear of connections (8), (9) and (10) by reason of the breaking currents. The structure is finally provided with a release spring (14) opposed by the chamber (4) pressure and which in turn acts as element resetting the pressurestat, which pressure reaches the chamber (4) from the washing drum through a duct (15) connected to the said drum by the system of communicating vessels.
Now then, from this basic and conventional construction, whether in a simple pressurestat, as in figures 2 and 3, or a multiple pressurestat as in figure 1, the first of the improvements subject hereof lies in that communication between the washing drum and the pressure chamber (4) is through two independent ducts. These independent ducts may be optionally provided directly in the pressurestat body (1), as shown in figures 1 and 2 and numbered (16) and (17), having respective nozzles (23), in which case the conventional nozzle at the duct (15) disappears, as shown in figure 3.
In either case it is achieved that the connection through communicating vessels between the washing drum and the pressure chamber (4) takes place through two nozzles (18) or (23), whence it is almost impossible for both to be simultaneously blocked, which naturally means that the risk of a blockage in time is also largely minimised.
Furthermore, and in accordance with another improvement subject of the invention, either using to such end a special single pressurestat as shown in figure 3, or in a module such as the one marked S in figure 1 when a multiple pressurestat, the release spring (14), against which the membrane (3) causes the connection tab (13) to trip, the latter doing so with the elastic sheet (16), is seated upon a push-button (24) and scaled in such a way that the said spring (14) cannot cause the pressurestat to be automatically reset, which latter will on the other hand only have been triggered when the working pressure exceeds a preset value and hence reaches an abnormal value, the pressurestat or pressurestat module's switch mechanism acting upon the washing machine's general supply circuit, causing the machine to stop and preventing the latter from carrying on working altogether, under any circumstance, until the said pressurestat is manually reset, specifically pressing the button (24), which will as aforesaid be done by a servicing expert after repairing the fault causing the said safety pressurestat to be activated.
The adopted item (19) carrying both ducts (21) and (22) leading into the washing drum shown in figure 3 can optionally be replaced by the item (25) which is in turn shown in figures 4 and 5 and which is also provided with both ducts (21) and (22) leading into the drum, having the same nozzles (23) but with the proviso that the said item (25) has pawls (26) allowing the same to be quickly attached to the edge or periphery of the pressurestat.
The adopted item (19) can also be replaced by that shown in figures 6 and 7 and numbered (27), above all when dealing with pressurestats having the inlet duct (15) located at the base, as in the case of the said figure 3, which item (27) is soldered ultrasonically to the pressurestat base (1).
Both when using the adopted item (25) and the adopted item (27), they are fitted with a seal such as in the case shown in figure 3, where the said seal is numbered (20).
We feel that the device has now been sufficiently described for any expert in the art to have grasped the full scope of the invention and the advantages it offers.
The materials, shape, size and layout of the elements may be altered provided that this entails no modification of the essential features of the invention.
The terms used to describe the invention herein should be taken to have a broad rather than a restrictive meaning.

Claims

1. Improvements to pressurestats, specifically pressurestats used in household appliances such as washing machines, wherein two chambers are defined, one being a pressure chamber and the other a mechanisms chamber, rendered independent through a membrane, the pressure chamber being related by a system of vessels leading to the machine's washing drum, such that the pressure within the same increases as the water level rises in such drum, which membrane acts through a pusher upon an elastic sheet and against a release spring, which elastic sheet is joined at one of Its ends to an electrical supply terminal, whereas the other end is provided with a terminal which can close two independent circuits, such as for instance that of the electric valve filling the drum and that of the water heater resistor, essentially characterised in that one of such improvements comprises providing two ducts leading into the pressure chamber, fitted with respective nozzles or restrictors, in order to reduce the risk of the communication with such pressure chamber being blocked.

2.- Improvements to pressurestats, as in claim 1, characterised in that both ducts into the pressure chamber are directly provided in the pressurestat body.

3.- Improvements to pressurestats, as in claim 1, characterised in that the pressurestat body retains the conventional and single inlet duct, lacking a nozzle or restrictor, and such single duct is tightly fitted with an adopted item, by means of fast coupling pawls to the edge or periphery of the pressurestat, by ultrasonic soldering or other means, which adopted item is in turn provided with two inlet ducts, communicating with the former, the latter having respective nozzles or restrictors.

4.- Improvements to pressurestats, as in claim 1, characterised in that the second of such improvements comprises providing a simple safety pressurestat or a safety module in a multiple pressurestat with a push-button supporting the contactor membrane's release spring, the said spring being appropriately scaled such that it is unable to cause the safety pressurestat to be reset, in the event of the latter being triggered by reason of an abnormal over-pressure in its pressure chamber due to a breakdown, the said pressurestat acting upon the machine's general supply circuit and the said push-button supporting the release spring having to be manually reset.