GB2251460A

GB2251460A - Pumping assembly with a reversible motor for a dishwasher.

Info

Publication number: GB2251460A
Application number: GB9123225A
Authority: GB
Inventors: Ugo Favret; Gianni Santarossa
Original assignee: Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1990-11-15
Filing date: 1991-11-01
Publication date: 1992-07-08
Anticipated expiration: 2011-11-01
Also published as: DE9114272U1; FR2669208B3; IT9034086V0; IT222242Z2; GB2251460B; GB9123225D0; FR2669208A1; IT9034086U1

Abstract

The invention relates to a dishwasher provided with a circulation pump and an emptying pump (10), the rotors of which are connected to a reversible drive shaft (13) of a motor to pump a fluid in alternate directions towards a corresponding outlet, when said shaft is rotating in one direction of rotation or in the other. The rotor (12) of the emptying pump is of the radial-blade type (14) and is housed in a chamber (17) provided with a circular sector (18) of its peripheral surface comprising a tooth (19) situated between the adjacent intake (9) and delivery (15) ports and having a reduced [small] internal diameter. The tooth (19) extends from said delivery port (15) towards said intake port (9) and the angle it subtends is smaller than the angle between said ports and greater than the angle between the blades (14) of the rotor (12). Applications: electrical household appliances. <IMAGE>

Description

DISHWASHER WITH A PUMPING ASSEMBLY WITH A REVERSIBLE MOTOR The present invention relates to a pumping assembly for an automatic dishwasher provided with a single reversible drive motor.

Dishwashers are known which are fitted with a pumping assembly designed for example as described in EP-A0268835, that is to say with a single reversible electric motor, on the drive shaft of which are keyed the rotors of a circulating pump and a discharge pump. The two pumps are actuated alternately in accordance with the direction of rotation of the shaft of the motor.

The circulating pump is preferably of the centrifugal type while the discharge pump is of the peripheral discharge flow type. In particular the rotor of the discharge pump is housed in a pumping chamber of substantially circular transverse cross-section, which is provided on its lateral wall surface with an intake port and a delivery port. The intake and delivery ports, which are respectively connected to the washing tub of the machine and to an external discharge conduit, are substantially mutually adjacent and are angularly separated by a portion of the lateral surface of the chamber which is of a reduced internal diameter and which is normally referred to as the "tooth" of the pump.

During the washing phases the discharge pump is actuated in its reverse direction of rotation whereby it produces a hydraulic pressure at its intake port, although that pressure is limited. During such phases, in particular at a position corresponding to the edge of the abovementioned "tooth" which is adjacent to the intake port of the discharge pump, the arrangement produces a vortical motion of fluid which undesirably involves the discharge circuit of the dishwasher. That vortex motion is in fact transmitted by way of the intake port of the discharge pump to the discharge circuit of the machine, causing the particles of dirt which are deposited there to be stirred up, so that they are then caused to re-circulate in the washing liquid. Consequently the level of washing efficiency of the machine can be substantially reduced.

The object of the present invention is to provide a dishwasher having a simple pumping assembly with a reversible motor which permits optimum operation substantially free from the above-mentioned problems.

More particularly it is an object of the invention to provide a dishwasher of the specified type in which, during the washing phases, the discharge pump does not cause the dirt deposited in the discharge circuit of the machine to be stirred up to any substantial degree.

In accordance with the invention there is provided a dishwasher pumping assembly comprising a circulating pump and a discharge pump, the rotors of which are connected to a reversible drive shaft of a motor for alternately pumping to the respective delivery port liquid which is respectively drawn in from a hydraulic washing circuit and a hydraulic discharge circuit of the dishwasher depending on the direction of rotation of said shaft, wherein the rotor of the discharge pump is of the peripheral discharge flow type and is accommodated in a pumping chamber of substantially circular transverse cross-section and comprising a tooth formed by an angular portion of the lateral surface of said chamber which is disposed between mutually adjacent intake and delivery ports and is of a reduced spacing from the rotor, and wherein said tooth extends from said delivery port towards said intake port with an angular extent which is less than the angular distance between said ports.

These and other features and advantages of the invention will be clearly apparent from the following description, given solely by way of non-limiting example, with reference to the accompanying drawings in which: FIGURE 1 diagrammatically shows the main components of the dishwasher according to the invention; and FIGURE 2 is a diagrammatic view in cross-section, on an enlarged scale, of a detail of the dishwasher shown in Figure 1, in a preferred embodiment.

Referring to Figure 1, the dishwasher mainly comprises a washing tub 4 (of which only part is shown) which is provided in its lower part with a filter arrangement generally indicated at 6, and a bowl 5 for collecting the washing water. Communicating with the bottom of the bowl 5 is the intake section of a circulating pump 7, preferably of centrifugal type. The pump 7 is capable of feeding at least one rotary spray arm assembly 8 for spraying the crockery to be washed, in known manner.

Further in per se known manner the bottom of the washing tub 4, which forms part of a discharge circuit of the dishwasher, also communicates with the intake port 9 of a discharge pump 10 whose delivery port 15 is connected to a hydraulic discharge conduit (not shown), preferably by way of a non-return valve 3.

The respective rotors 11 and 12 of the pumps 7 and 10 are for example designed as described in above-mentioned EP-A-0268835, and are keyed on a common drive shaft 13 of a reversible electric motor 16. The rotors 11 and 12 are capable of alternately pumping, to the delivery of the associated pump 7 or 10, the water which is drawn in at the respective intake zone.

In particular the circulating pump 7 or the discharge pump 10 is alternately operable during a washing phase or a discharge phase respectively when the drive shaft 13 is actuated in a first or a second direction of rotation.

Referring also to Figure 2, the rotor 12 of the discharge pump 10 is of the peripheral discharge flow type provided with radial vanes 14, and is accommodated in a pumping chamber 17 of substantially circular transverse cross-section. The intake port 9 and the delivery port 15 extend tangentially from respective zones of the lateral wall surface of the chamber 17. In particular the intake port 9 and the delivery port 15 are adjacent to each other and define between them an angular sector 18 of the pumping chamber 17, at which the chamber is internally provided with a portion 19 (referred to herein as the "tooth" of the pump) in the form of a segment of a circular ring. In per se known manner the tooth 19 is of a reduced internal diameter which is only slightly larger than that of the rotor 12, and it is preferably formed integrally with the chamber 17.

The tooth 19 extends from the delivery port 15 towards the intake port 9 with an angular extent which is less than that of the sector 18 of the chamber 17. In that way the edge 20 of the tooth 19 which is towards the intake port 9 of the pump is relatively spaced from the intake port. Therefore when, during the washing phases, the discharge pump 10 is actuated in its reverse direction of rotation (that is to say in the clockwise direction in the construction shown in Figure 2), the vortical motion of liquid (shown by arrows in Figure 2) which inevitably occurs in the chamber 17 upstream of the edge 20 is "trapped" in the zone, adjacent to the sector 18, which is between the tooth 19 and the intake port 9. Advantageously therefore that vortical movement does not substantially affect the intake port 9 of the pump 10, and the discharge circuit of the dishwasher which is connected thereto continues to be in a calm condition which ensures temporary stagnation of the particles of dirt. In a conventional manner the dirt is passed to the discharge conduit by way of the valve 3 during a subsequent discharge phase in which the pump 10 is actuated in the intended direction of rotation (anticlockwise), with levels of performance which are not substantially altered by the above-indicated characteristics of the tooth 19.

The effect of "trapping" the vortical fluid motion will be increased in proportion to a decreasing angular extent of the tooth 19; the angle subtended by the tooth 19 will preferably be greater than the angular distance between the adjacent vanes 14 of the rotor 12 (to avoid substantially direct communication between the intake and the delivery of the pump).

The above-mentioned "trapping" effect can also be increased by providing in the chamber 17 a deflector 21 which extends in register with the intake port 9 tangentially from the edge of the angular sector 18 which is contiguous with the intake itself. Preferably the deflector 21 is substantially rectilinear and integral with the chamber 17. At any event it increases the degree of separation of the discharge circuit of the machine from the above-mentioned vortical motion which occurs during the washing phases.

The manner in which the aims of the invention are achieved in a particularly simple fashion will be apparent from the foregoing description.

It will be appreciated that the dishwasher described may be the subject of numerous modifications which fall within the scope of the invention, subject to the following claims.

Claims

1. A dishwasher pumping assembly comprising a circulating pump and a discharge pump, the rotors of which are connected to a reversible drive shaft of a motor for alternately pumping to the respective delivery port liquid which is respectively drawn in from a hydraulic washing circuit and a hydraulic discharge circuit of the dishwasher depending on the direction of rotation of said shaft, wherein the rotor of the discharge pump is of the peripheral discharge flow type and is accommodated in a pumping chamber of substantially circular transverse cross-section and comprising a tooth formed by an angular portion of the lateral surface of said chamber which is disposed between mutually adjacent intake and delivery ports and is of a reduced spacing from the rotor, and wherein said tooth extends from said delivery port towards said intake port with an angular extent which is less than the angular distance between said ports.

2. A dishwasher pumping assembly according to claim 1, wherein the rotor of the discharge pump is of the radial vane type and said tooth subtends an angle which is greater than the angular distance between adjacent vanes of said peripheral discharge flow rotor.

3. A dishwasher pumping assembly according to claim 1, wherein said intake and delivery ports define between them an angular sector of said chamber comprising said tooth, and wherein said chamber is provided with a deflector extending in register with the intake port tangentially from the edge of said angular sector which is contiguous to said intake port.

4. A dishwasher pumping assembly constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.

5. A dishwasher including a pumping assembly according to any one of the preceding claims.