GB2240708A

GB2240708A - Dishwashing or laundry washing; pump with flow regulator

Info

Publication number: GB2240708A
Application number: GB9100563A
Authority: GB
Inventors: Ugo Favret
Original assignee: Industrie Zanussi SpA
Current assignee: Industrie Zanussi SpA
Priority date: 1990-02-09
Filing date: 1991-01-10
Publication date: 1991-08-14
Anticipated expiration: 2011-01-10
Also published as: ES1016267Y; GB9100563D0; FR2658067A1; ES1016267U; FR2658067B3; GB2240708B; IT223506Z2; SE9100203L; IT9034011V0; SE504116C2; DE9101453U1; SE9100203D0; IT9034011U1

Abstract

A dishwashing or a laundry washing machine comprises a centrifugal watercirculating pump including a volute in which the pressure of the water flow increases from the intake of the pump towards its outlet, and in which means are provided for regulating the water-flow, characterised in that the regulating means comprise a baffle 15 (or 17. Figs 4-6) disposed in the volute 13 and manually movable between a rest position and an operative position in which the flow cross- section for the water in the volute is greatest and is reduced, respectively. <IMAGE>

Description

Dishwashing or laundry washlnc;PumP with flow regulator.

The present invention relates to a washing machine, particularly a dishwashing machine, including a pump for circulating water to a washing tub.

As is known, in dishwashers in particular, the circulating pump is preferably of the centrifugal type and draws water from a collecting tank in order to supply one or more swivelling spray heads which spray the dishes in the washing tub. The water then collects in the tank again, completing a closed hydraulic circuit.

In a modern dishwasher, for example, of the type described in EP-B-0152893, the dimensioning of the hydraulic circuit is generally critical to an overall saving in energy; in particular, substantially less water is used to carry out a washing cycle and the capacity of the collecting tank is therefore small.

In most European dishwashers, the entire hydraulic circuit is dimensioned for a circulating pump supplied with alternating current at 50 Hz; if the machine were installed in a country with a different standard electrical supply (60 Hz in the United States and in some regions of Japan, for example) its general malfunctioning could result. In particular, because of the critical dimensions of the hydraulic circuit of the dishwasher, if the circulating pump is supplied at 60 Hz, its hydraulic impeller will rotate too fast and the pump will be primed intermittently in use, which will adversely affect the overall operation of the dishwasher.

Naturally, this phenomenon could be minimised by the use of known flow regulators which, for a centrifugal pump, may consist of a regulator at the outlet of the pump (where the hydraulic pressure is greatest} or of a device for adjusting the inclinations of the vanes of the pump impeller. Both solutions are undesirably complex and expensive, however, and are thus impractical for use in a domestic washing machine; in fact, they are only used with high-performance pumps and for relatively complicated equipment.

The main object of the present invention is to provide a washing machine with a centrifugal circulating pump which can operate in an optimum manner regardless of the frequency of the supply voltage.

More particularly, the object of the present invention is to provide a washing machine which has a centrifugal circulating pump with flow-regulating means which are particularly simple, effective and convenient in use.

According to the invention, these objects are achieved in a washing machine with a centrifugal circulating pump which incorporates the characteristics of the appe#nded claims.

The characteristics and advantages of the invention will become clearer from the following description provided purely by way of non-limiting example with reference to the appended drawings, in which: Fig. 1 shows schematically the main components of a first embodiment of the washing machine according to the invention, Figs. 2 and 3 are cross-sections showing, on an enlarged scale, a detail of the washing machine of Fig.

1 in respective operative conditions, Fig. 4 shows a variant of the washing machine of Fig.

1, Figs. 5 and 6 are cross-sections showing, on an enlarged scale, a detail of the washing machine of Fig.

4 in respective operative conditions.

With reference to Figs. 1, 2 and 3, the washing machine according to the invention is preferably a domestic dishwasher and includes essentially a washing tub 7 (shown only partially) with a tank 8 at the bottom for collecting the washing and rinsing water. The bottom of the tank 8 communicates with the intake of a centrifugal circulating pump 9 driven by an electric motor 20. The outlet 10 of the circulating pump 9 is adapted to supply at least one rotary head 11 for spraying the dishes to be washed in known manner. The circulating pump 9 (together with its drive motor and the entire hydraulic circuit associated therewith) is preferably dimensioned so as to operate with a 220V, 50 Hz supply voltage. In conventional manner, it includes a hydraulic impeller 12 housed in a spiral pressure chamber or volute 13.In particular, as shown in Fig. 1, the radius of the cross-section of the volute 13 increases progressively from a starting point where the volute forms a so-called "tooth" 14 with the outlet 10 so as to define a so-called Archimedean spiral. As is known, when the centrifugal pump 9 is in operation, the hydraulic pressure in the volute 13 increases progressively from the "tooth" 14 to the outlet 10.

According to one aspect of the invention, the pump 9 includes flow-regulating means in the volute 13, the means being -movable between a -rest position- and--an operating position in which the flow cross-section for the water, defined by the inner walls of the volute 13 and by the impeller 12, is greatest and is substantially reduced, respectively. Preferably, the regulating means are arranged in the region of the volute 13 where the hydraulic pressure is lowest.

With reference to Figs. 1, 2 and 3, in the simplest embodiment, the regulating means may comprise a baffle or gate 15 slidable sealingly in an opening 16 in the volute 13. The baffle 15 can be moved, preferably manually, between a normal rest position (Fig. 2) in which it is substantially outside the volute 13 and an operative position (Fig. 3) in which it is substantially inside the volute 13, reducing the flow cross-section for the water.

Preferably, the two positions are defined by respective stops of known type, not shown.

With reference now to Figs. 4, 5 and 6, in a variant which is more convenient in use, the flow-regulating means comprise a baffle 17 fixed to a pin 18 by means of which the baffle is hinged to the wall of the volute 13. The baffle 17 extends, for example, substantially radially in the volute 13 and the pin 18 extends sealingly through the wall of the volute. A knob 19 or the like is keyed to the pin 18 outside the volute so that the baffle 17 can be pivoted manually between a rest position (Fig. 5) and an operative position (Fig.

6), in which it is arranged parallel to and transverse the flow of water in the volute 13 respectively. In practice, the baffle 17 has no effect on the flow of water over it in the rest position whilst, in the operative position, it substantially reduces the flow cross-section for the water. The two positions of the baffle 17 in this embodiment are also preferably defined by respective stops of known type, not shown.

The water-collecting tank 8 and the circulating pump 9 are preferably formed substantially as described, for example, in GB-B-2049406, that is to say, the pump 9 is arranged with its axis horizontal and the portion of the volute 13 adjacent the "tooth" 14 (where the hydraulic pressure is lowest) is accessible directly from inside the washing tub 7. The baffle 15 or the knob 19 are thus also conveniently accessible.

In either case, when the washing machine is installed in an area with a 50 Hz electricity supply, the flow-regulating means 15 or 17 are arranged in the rest position, allowing the circulating pump 9 to operate wholly conventionally at the nominal flow-rate for which it is designed.

With a 60 Hz supply, however, the flow-rate of the same circulating pump 9 would increase by about 15%-20%.

In order to compensate for this undesired change in the flow-rate, the baffle 15 or 17 is disposed in its operative position so that the flow cross-section for the water in the volute 13 is reduced appropriately. An expert in the art can easily calculate the size of the baffle 15 or 17 in dependence on the technical characteristics of the centrifugal pump 9 so that the flow-rate can also be kept at its nominal value in these circumstances.

The structural and functional simplicity of the washing machine according to the invention is clear from the description and, moreover, its flow-regulating means are particularly reliable since they are situated in a region of the volute 13 where the hydraulic pressure is lowest and are thus subject to little mechanical stress.

Naturally, the washing machine described may be modified in many ways without thereby departing from the scope of the invention.

For example, the washing machine may be a laundry-washing machine of the type described in EP-B-0146719, in which the centrifugal pump circulates water from a collecting tank to a washing drum connected together in a closed hydraulic circuit.

Moreover, the baffle 15 or 17 can be be adjusted, even in a linear manner, to at least one position intermediate its rest position and its operative position so that the performance of the pump can be adapted to particular operating conditions.

Claims

1. A washing machine with a centrifugal water-circulating pump including a volute in which the pressure of the water flow increases from the intake of the pump towards its outlet, and in which means are provided for regulating the water-flow, characterised in that the regulating means comprise a baffle (15; 17) disposed in the volute (13) and movable between a rest position and an operative position in which the flow cross-section for the water in the volute is greatest and is reduced, respectively.

2. A washing machine according to Claim 1, characterised in that the baffle (15; 17) is located in the region of the volute (13) where the pressure of the water-flow is lowest.

3. A washing machine according to Claim 1, characterised in that the baffle (15) is of the gate type and slides sealingly between its rest position and its operative position in an opening (16) in the wall of the volute (13).

4. A washing machine according to Claim 1, characterised in that the baffle (17) is fixed to a pin (18) by means of which it is hinged to the wall of the volute (13), within the latter, so that it can be pivoted between its rest position and its operative position.

5. A washing machine according to Claim 4, characterised in that the pin (18) extends sealingly through the wall of the volute (13) and is fixed for rotation to a manually-operable knob (19) outside the volute.

6. A washing machine according to Claim 1, characterised in that the baffle (15; 17) can be adjusted to at least one position intermediate its rest position and its operative position.