GB2107098A

GB2107098A - Household appliance with pump operation monitoring means

Info

Publication number: GB2107098A
Application number: GB08220013A
Authority: GB
Inventors: Rudolf Grunwald
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-09-16
Filing date: 1982-07-09
Publication date: 1983-04-20
Also published as: IT1152554B; DE3136769A1; GB2107098B; FR2512853B1; FR2512853A1; IT8223232A0; DE3136769C2

Abstract

A water-conducting household appliance comprises an electrically operated pump (13), air-cooled by its own fan (3), for supplying cleaning and rinsing liquid. Disposed in the air stream (2) generated by the fan (3) is a signal device, the influencing of which caused by the air stream can be converted into a signal. The signal device can comprise a vane (15, 16) mounted in the air stream created by the fan and deflectable thereby across a viewing opening (9) to provide a visual indication that the fan, and hence the pump, is in operation. <IMAGE>

Description

SPECIFICATION Household appliance with pump operation monitoring means The present invention relates to a household appliance, especially a water-conducting household appliance with an electrically driven pump, air-cooied by its own fan, for delivering cleaning and rinsing liquid.

It is generally known to monitor an electrical consumer by connecting an indicator lamp or the like in parallel therewith. If this indicator lamp indicates its operating state, then the electrical consumer is connected to voltage. In general it is concluded therefrom that the electrical consumer is correctly operating.

The motor of an electrically driven pump can indeed be correctly switched on, i.e. be connected to operating voltage, but nevertheless the pump might not be running correctly. If, for example, the pump impeller is obstructed by bulky objects, its rotation may be prevented, with the consequence that on the one hand its task is not fulfilled and on the other hand the drive motor thereof can suffer damage. This faul cannot, however, be recognized by the above-described monitoring device.

There is accordingly a need for a means of singalling to the operator of a household appliance if a pump is not correctly operating. Due to the large number of components for such household appliances it is desirable for the cost of the signalling means not to substantially exceed twothousandths of the total price of the appliance.

According to the present invention there is provided a household appliance comprising an electrically driven pump for pumping liquid, the pump being provided with a fan for generating an air current to cool the pump, and a signal device arranged in the flow path of the fan to be so influenced by the current as to provide a signal.

In a preferred embodiment, the signal device is disposed in the air stream or current generated by the moving fan, the influencing of the device caused by the air stream being converted into a signal. Such a construction is capable of monitoring the pump operation according to whether the cooling fan for the pump drive motor is running at a rotational speed which results in a sufficient air stream for influencing the signal device. The assembly can be so designed that this rotational speed corresponds to a minimum rotational speed for correct operation of the pump.

This arrangement permits forms of construction which minimise costs.

In one of the simplest and least expensive embodiments of the invention, the signal device includes a vane which can be deflected by the air stream.

This vane can itself serve as a visible signal when in the deflected state. Thus, any further expenditure on the assembly of the signal device is dispensed with.

Alternatively, the vane can be mounted in an articulated manner such that in the deflected state it closes a viewing opening in the external casing of the appliance. The provision of a viewing opening for monitoring the position of the vane involves only the additional cost for a closure glass to prevent access to the interior of the appliance that might be undesirable for safety reasons.

If the vane has the same colour, in the region of the viewing opening, as the casing, then the signalling of a non-running pump is achieved by the fact that the absence of the vane at the viewing opening makes the latter appear dark. In the case of the correct operation of the pump, the viewing opening will appear to be of the same colour as the casing and will not be noticeable.

According to another embodiment, the vane has an aperture which, when there is no influence from the air stream, lies in the path of a beam from a light source to the viewing opening in the appliance housing. This does result in a small increase in the cost of the signal device, although still within acceptable limits. With this embodiment, however, the ease of recognition of a "pump stopped" signal is considerably improved.

Since the pump and associated signal device are usually disposed, for example in a washing machine, near to the floor, in a further embodiment of the invention the viewing opening in the housing is equipped with a light diffusing lens. This diffusing lens can be so constructed that the light rays are deflected from the beam to the eye of the operator when standing in front of the appliance.

In an embodiment of a different type, the signal device is a temperature-dependent resistor. If, when the pump is operating, the air stream passes over this temperature-dependent resistor, then the resistor cools down and changes its electrical resistance in a manner which can be converted to a signal.

Such an arrangement has the advantage that the signalling of a pump which is not operating correctly takes place only in a phase during the operation of the appliance in which the pump should be running. An especially inexpensive and advantageous embodiment comprises a circuit assembly in which the temperature-dependent resistor is an NTC resistor and is connected in series with an electrical indicator light source, this series circuit being directly connected in parallel to the wining of the pump motor. The indicator light source can only light up if the pump motor winding is connected to voltage, that is to say has been switched on by a switch internal to the device, for example a programme switch.The mean electrical reistance of the uncooled and deenergized NTC resistor is still so high that the indicator light source cannot light up at the instant of switching on of the pump motor. It is only when the non-running pump cannot cool the NTC resistor, that the temperature of the NTC resistor rises by resistance heating and thereby reduces its electrical resistance. The light source can then receive sufficient voltage and current to light up. If, however, the NTC resistor is cooled by an air stream generated through correct operation of the pump, then its temperature will fall and its electrical resistance will increase. Thus, switching on of the light source is prevented. A switched-on light source can therefore indicate a fault at the pump with reliability.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings in which: Fig. 1 is a schematic view of a pump fan and a signal device with a pivotal vane in the lower part of a household appliance according to a first embodiment of the invention; Fig. 2 is a schematic view of a simplified form of signal device in an appliance according to a second embodiment of the invention; Fig. 3 is a schematic plan view of a signal device in an appliance according to a third embodiment of the invention; Fig. 4 is a plan view of the signal device of Fig. 3 Fig. 5 is a schematic view of a fan with a temperature-dependent resistor as a signal device in an appliance according to a fourth embodiment of the invention; and Fig. 6 is an electrical circuit diagram for a signal device such as that of Fig. 5, the device including a glow discharge lamp.

Referring now to the drawings, in each of Figs.

1 to 5 there is shown a portion of a household appliance having an external housing with a front wall 1. In Fig. 1, an air stream 2 from a fan 3 is directed onto a pivotal vane 4, which is pivotally mounted in a bearing block 5. In order that the vane can adopt the rest position illustrated in Fig.

1, it carries a weight 6 on a load arm thereof.

Mounted on the bearing block 5 is a light source 7, the rays of which pass through an aperture 8 in the vane 4 towards a viewing opening 9 in the front wall 1. The opening 9 is, for safety reasons, protected by a closure glass 10 against manual penetration by operating persons. To improve recognition of the light signal, the surface of the closure glass 10 is broken up in such a manner that the rays impinging internally from the light source 7 are deflected upwards to the eye of the operator.

As soon as the air stream 2 strikes the vane with sufficient force, the vane is pivoted into the position illustrated in dashed lines, so that an unperforated surface portion thereof comes to bear against the inside of the glass 10 and screens the rays from the light source 7. The glass 10 therefore remains dark. The light source 7 can advantageously be so connected that it always lights up only when the motor of the pump which drives the fan 3 (neither motor nor pump are illustrated in Figs. 1 and 2) is connected to voltage.

A simplified design corresponding to the principle illustrated in Fig. 1 is shown in Fig. 2.

Here the vane consists of a foil 1 1 glued inside the appliance onto, for example, the front wall 1. In the rest state, i.e. when uninfluenced by the air stream 2, the foil adopts the position shown in solid lines. For this purpose it is folded as illustrated. In this condition the viewer sees a dark space in a noticeable manner behind the viewing opening 9. It is therefore immediately evident that the pump is not running. As soon as the air stream 2 develops sufficient force, it presses the foil 11 over the viewing opening 9. In an advantageous manner the external surface of the foil 1 1 can have the same colour as the external surface of the front wall 1. Then, when the pump is operating, a consistent external image is obtained; no irregularity is evident to the viewer on the surface of the front wall and there is thus no indication of pump stoppage.

In Fig. 3 there is shown a wash liquor pump which is driven by an electric motor 13, the rear end of the output shaft of which carries the fan 3.

On the inner side of the front wall 1, a vane 15 is mounted by means of a bearing block 14 suspended perpendicularly to the front wall 1, and is equipped with a light stop 16 disposed parallel to the front wall 1 behind the viewing opening 9.

In Fig. 4 the vane with light stop is shown in front view. From this it can be seen that the light stop 1 6 possesses two zones of different colour, of which the zone 17 has the same colour as the front wall 1 and the zone 18 has, for example, a red colour. Thus, with the usual white front wall 1 of household appliances, the colour zone 17 is likewise white. In the rest position of the vane 15.

unfluenced by the air stream 2 and illustrated here, the light stop 16 adopts a position behind the viewing opening 9 which renders the red colour zone 1 8 visible. As soon as the pump 12 and the fan 3 run, the air stream 2 pivots the vane 1 5 as far as the stop 19, so that the white colour zone 17 of the light stop 16 appears of uniform colour, so that no indication is given to the operator that the pump may not be running. It is only when the air stream 2 is lacking or its force is not sufficient for deflecting the vane 15 that the red colour zone 18 is situated behind the viewing opening 9 and thereby signals to the operator in a readily visible manner that the pump is not running.

In the embodiment illustrated in Fig. 5, the air stream 2 from the fan 3 is directed onto a temperature-dependent resistor RT, the connecting wires of which are soldered into a circuit board 20. The circuit board is connected, by means of an edge plug connector 22 mounted on a bearing block 21, via an electrical conductor 23 with the remaining electrical equipment of the appliance.

The electrical equipment of the household appliance includes a circuit assembly according to Fig. 6, in which the motor M of the liquor pump is connected via a programme switching contact PK to mains conductors R and MP. Directly in parallel with the winding of the motor M, the temperature dependent resistor RT is connected in series with a parallel circuit. The parallel circuit here consists of a series resistor RS and a glow discharge lamp GL with a compensating resistor RV. The fan coupled to the motor acts by means of its cooling air stream directly on the temperature-dependent resistor RT.

For explaining the functioning of the circuit, it may be assumed that the temperature-dependent resistor RT is an NTC resistor, i.e. its electrical resistance decreases with increasing temperature.

The individual elements of the circuit are so designed that the resistor RT has a mean resistance value when the contact PK makes the connection. The voltage drop across the resistor RT is then still so large that the ignition voltage of the lamp GL is not yet reached. If the motor M remains stopped, in spite of the electrical connections having been made via the contact PK, then the cooling of the resistor RT fails. The resistance heat now converted in it raises its temperature to such an extent that with decreasing resistance value there is a continuously decreasing voltage at the NTC resistor. Thus the voltage across the series resistor RS rises, until finally the ignition voltage of the lamp GL is reached and the lamp lights up. This is the signal for the operator that the pump has stopped and is out of order, for example is blocked by a solid object in the pump casing.The operator can be told, for example from the operating instructions, to inspect the pump in such a case.

If, by contrast, the motor M starts up immediately the electrical connection has been made by the contact PK, then cooling of the resistor RT immediately commences, the temperature of which thereby sinks and the electrical resistance of which increases. The voltage at this resistor then, however, increases, so that the ignition voltage for the lamp cannot be reached and the lamp remains unlit.

The illustrated circuit is self-evidently only one possibility of construction for the arrangement of a temperature-dependent resistor as signal device.

Where the electrical resistance values are sufficiently small, a PTC resistor can instead be connected in series with the motor winding, and an indicator light source connected in parallel with the PTC resistor. This arrangement would indeed have the advantage that, with electrical resistance increasing with increasing temperature, the current in the circuit of the pump motor would fall and thereby protect the winding of the pump motor. As indicator light source, a glow discharge lamp as illustrated or a conventional incandescent lamp may be provided. The provision of a luminous diode is, however, also possible.

Claims

1. A household appliance comprising an electrically driven pump for pumping liquid, the pump being provided with a fan for generating an air current to cool the pump, and a signal device arranged in the flow path of the fan to be so influenced by the current as to provide a signal.

2. An appliance as claimed in claim 1, wherein the signal device comprises a vane mounted to be deflectable by the current.

3. An appliance as claimed in claim 2, wherein the vane is so arranged in the housing as to provide a visual signal in its deflected position.

4. An appliance as claimed in claim 3, comprising an external housing provided with a viewing opening, the vane being so mounted as to close the opening with its deflected position.

5. An appliance as claimed in claim 4, wherein the vane is adapted to close the opening by a portion having the same colour as that of the housing.

6. An appliance as claimed in claim 2, comprising an external housing provided with a viewing opening, the signal device further comprising a light source arranged to emit a beam of light towards the viewing opening and the vane being provided with an aperture to permit passage of the beam to the viewing opening when the vane is not deflected by the current.

7. An appliance as claimed in claim 6, comprising a light-diffusing lens arranged at the viewing opening.

8. An appliance as claimed in claim 1 , wherein the signal device comprises a temperaturedependent resistor.

9. An appliance as claimed in claim 8, wherein the resistor is a negative temperature coefficient connected in series with an electrical light source, the resistor and light source being connected in parallel with the winding of an electric motor of the pump.

10. An appliance as claimed in any one of the preceding claims, the appliance being waterconducting apparatus and the pump being arranged to convey cleaning and rinsing liquid.

11. A household appliance substantially as herinbefore described with reference to Fig. 1 of the accompanying drawings.

12. A household appliance substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

13. A household appliance substantially as hereinbefore described with reference to Figs. 3 and 4 of the accompanying drawings.

14. A household appliance substantially as hereinbefore described with reference to Figs. 5 and 6 of the accompanying drawings.