EP0962182A1 - Device for the liquid supply and dosage in a domestic washing machine tub, in particular a dishwashing machine - Google Patents

Device for the liquid supply and dosage in a domestic washing machine tub, in particular a dishwashing machine Download PDF

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Publication number
EP0962182A1
EP0962182A1 EP99110526A EP99110526A EP0962182A1 EP 0962182 A1 EP0962182 A1 EP 0962182A1 EP 99110526 A EP99110526 A EP 99110526A EP 99110526 A EP99110526 A EP 99110526A EP 0962182 A1 EP0962182 A1 EP 0962182A1
Authority
EP
European Patent Office
Prior art keywords
tub
liquid
detection means
float
conduit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99110526A
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German (de)
English (en)
French (fr)
Inventor
Giuseppe Borroni
Carlo Carli
Emilio Cazzini
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
T&P SpA
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T&P SpA
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Filing date
Publication date
Application filed by T&P SpA filed Critical T&P SpA
Publication of EP0962182A1 publication Critical patent/EP0962182A1/en
Withdrawn legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47L—DOMESTIC WASHING OR CLEANING; SUCTION CLEANERS IN GENERAL
    • A47L15/00—Washing or rinsing machines for crockery or tableware
    • A47L15/42—Details
    • A47L15/4244—Water-level measuring or regulating arrangements

Definitions

  • the present invention refers to a device for the liquid supply and dosage in the tub of a domestic washing machine, in particular a dishwasher.
  • dishwashers it is known for dishwashers to comprise a washing tub, on whose bottom water from the mains is collected as required for the washing of the crockery; to this purpose, the machine has a washing or re-circulating pump to supply said water collected on the tub bottom to one or more spraying elements.
  • Water dosage as required for the washing can be performed in several ways.
  • the simplest solution is to provide a time-operated opening of a solenoid valve for water intake in the washing tub; however, such a method, practically given up by now, may prove poorly accurate as it does not consider the pressure changes that may always occur in the water supply mains and consequent changes in the flow-rate of the solenoid valve.
  • the most spread solution is to realize the washing water dosage through an electro-pneumatic pressure switch, which through an air trap is apt to detect the water level directly inside the wash-tub, so as to ensure a control principle of the intake solenoid valve from the mains.
  • the fact that the air trap required for the pressure-switch operation is located practically inside the wash-tub, may determine a malfunction of the system, due to soil particles depositing right in the air trap.
  • the water level to be reached inside the washing tub is predetermined through a proper height location of a siphon, so that as soon as a tiny amount of water exceeds the siphon bend, a detection device will immediately stop the electric supply of the solenoid valve.
  • the shape of the floats employed in such solutions may also lead to a lack of detection accuracy, as they are subject to frictions.
  • Such floats in fact, tend to adhere to or possibly become embedded in the walls of the relevant housing chamber, as well as collect soil particles.
  • the dishwashing machine comprises a metering tank branched off the water supply pipeline to the wash-tub, so that an amount of water from the mains will reach the tub directly and another portion said tank.
  • the metering tank has a reduced water capacity compared to the amount of water required for washing and contains a float level sensor, which therefore operates on a small amount of water, which is proportional to the amount supplied to the tub; upon reaching the predetermined level in the tank, it will cause the water intake solenoid-valve to close.
  • the level sensor operates on a fraction of the water supplied to the tub, filling a small tank to minimize detection faults.
  • water intake and dosage systems which provide a repeated water intake to one or more tanks, whose capacity equals a fraction of the capacity required for washing; also in this instance, at least one tank has a cylindrical or parallelepiped float level sensor, to control a standard intake solenoid-valve; water supply to the wash-tub occurs by subsequent transfers from the tank to the tub itself.
  • dosage solutions as presently known and employed can be classified in two categories according to their detection system:
  • a further aim of the present invention is to provide a device as described above, which has an improved reliability, by virtue of appropriate means to hinder the back-flow of soil residuals, possibly retained in the washing tub, to the liquid dosage means.
  • Fig. 1 shows schematically a portion of the hydraulic circuit of a washing machine according to the features of the present invention; in the example represented in the figure the invention is applied on a dishwashing machine.
  • reference 1 indicates a connection to the water mains (such as a tap) being connected to a conduit 2 for supplying the water from the mains to the dishwasher; on this conduit 2 a solenoid valve 3 controls the supply of the mains water to the dishwasher; on the conduit 2, downstream of the solenoid valve 3, a non-return device 4 generally known as air-breaker and a softening device 5 are arranged in series.
  • the softening device 5 may not be absolutely required for a dishwasher, provided water hardness in the area where the latter is installed has a low degree.
  • a dosage device 6 is provided for the washing liquid, manufactured according to the features of the present invention; a T-tube connects the device 6 to a washing tub 7 of the machine, which has a drain conduit 8 being connected to a suitable discharge pump 9.
  • the device 6 is housed outside the washing tub 7, in a position away from it; moreover, according to the given example, the device 6 is placed slightly higher than the bottom of the tub 7.
  • the tub 7 is also in communication with a proper washing or re-circulating pump P, which supplies one or more spraying elements I with the liquid collected from the bottom of the tub 7; also the above spraying elements and the washing pump are per-se known for their manufacture and operation, so they will not be further described here in detail.
  • Fig. 2 shows schematically a possible embodiment of the dosage device 6; in this figure the portion of the conduit 2 from the softening device 5 has a different shape compared to the one illustrated in Fig. 1; however, the operation of the device 6 is substantially similar in both embodiments.
  • the device 6 comprises a body 11 made of plastic material, for example consisting of two hot blade welded polypropylene shells, wherein a connector is defined, being indicated with R as a whole.
  • the connector R has a first connection 12 to the conduit 2 and a second connection 13 to the tube T; as it can be seen, the connection 12 and the tube 2 have a smaller section compared to the connection 13 and the tube T.
  • the two chambers 16A and 16B communicate in their lower part with the duct C2 and are open upwards (i.e. in communication with the atmosphere); also the chamber 16C is open upwards, but isolated with respect to the chambers 16A and 16B.
  • Fig. 3 shows schematically a front view of the connector R, where ducts C1, C2 and C3 can be seen; in this figure a seat indicated with S is provided, for fastening a non-return valve, indicated with V in Fig. 2, which is assembled on the connection 13.
  • the valve V shown as a side and front view in Fig. 4, essentially consists of a rubber element or analogous material with a peripheral ring V1, which is apt for elastic coupling with the seat S of the connector R, and a central part V2, which in its rest position is at least apt to close ducts C1 and C2 with respect to the connector 13;
  • V3 indicates spaced edges connecting the central portion V2 to the peripheral ring V1;
  • V4 indicates openings being present on the peripheral ring V1; the duct C3 will never be completely closed by the central portion V2, due to the dimensions of the central section V2 and the presence of the spaced edges V3 and the openings V4.
  • references 17A and 17B indicate two floats, made from a polymer, which are inserted in chambers 165A and 16B, respectively and are apt to slide within them; according to an important aspect of the present invention, the floats 17A and 17B have a ball or spherical shape, made for instance of polypropylene or blown and tumbled polystyrene.
  • References 18A and 18B indicate two electric micro-switches, whose type and operation are commonly known, fastened in the upper section of the body 11.
  • the micro-switches 18A and 18B have respective control rods 19A and 19B, which are apt to be moved by the balls 17A and 17B, and tend to raise up in the chambers 16A and 16B during the water filling steps of the washing tub 6, as further detailed.
  • the ball 17A and the micro-switch 18A are provided for the level control of the liquid supplied to the tub 7, whereas the ball 17B and the micro-switch 18B are provided for safety purposes, should the first micro-switch 18A fail to operate.
  • the rod 19B of the micro-switch 18B is arranged for switching at a higher limit, i.e. a safety limit, which is higher compared to the position and threshold of the micro-switch 18A and its relevant rod 19A.
  • a programmer device or timer (not represented for simplicity's sake) actuates the opening of the solenoid valve 3.
  • Water can then pass in the connector 13 and further along the tube T, so reaching the washing tub 7, which is gradually filled with water.
  • the water supply to the tub 7 continues until the ball 17A shifts the rod 19A of a preset angle, causing the micro-switch 18A to switch.
  • This switching constitutes a control signal for stopping the electric supply of the solenoid valve 3, and therefore make it to close. Therefore, under this condition, the tub results in being filled up to a predetermined water level, depending on the operation threshold determined by the work position of the micro-switch 18A.
  • control signal is also to let the electric motor of the machine programmer or timer to start again (during the water supply from the mains, said motor is typically at standstill), for enabling the execution of the subsequent phases being provided by the washing cycle.
  • valve V goes back to its initial rest position, so closing the connector 13 as illustrated in Fig. 5.
  • the valve V is maintained in its closed position not only by the elastic force of the edges V3, but also and above all by the water pressure tending to raise up in the tube T, in the direction of the arrow F.
  • the micro-switch 18B operates to hinder the water Level in the tub 7 from exceeding a predetermined safety limit, being defined by the operation threshold of the micro-switch 18B itself, to avoid a possible flooding.
  • Said "resetting" of the micro-switches which follows a water discharge is not necessarily such to automatically enable a new opening of the solenoid valve 3, since the latter is anyway also subject to the control of the dishwasher programmer.
  • the chamber 16C and its relevant duct C3 are advantageously employed in washing machines, in particular dishwashing machines provided with the so-called “dynamic” water supply or water dosage systems, i.e. such systems where the washing pump is activated before the water supply from the mains has ended.
  • the preset level detected on the tub bottom for closing the supply solenoid valve equals a water volume actually smaller than the one being present in the hydraulic circuit of the dishwasher; under this condition, in fact, some liquid is circulating through the washing pump and the relevant spraying elements.
  • washing pump would stop and the water within the spraying circuit fall down to the tub bottom, with its consequent level increase.
  • the liquid in the spraying circuit falling down will surely determine a water back-flow along the tube T, which fact is possible due to the presence of duct C3.
  • valve V is designed to close ducts C1 and C2 but not duct C3, not even under the condition represented in Fig. 5.
  • the dishwasher hydraulic circuit may possibly be so designed that when the washing cycle is interrupted as mentioned above, a portion of the liquid raising up along the tube T can reach the chamber 16C; it should be appreciated that no particular problems exist if such a liquid contains some dirt rests, as the chamber 16C is not used for dosage purposes and contains no means for this purpose, such as floats and micro-switches.
  • the washing pump operates again sucking the water collected on the tub bottom and recalling also the water possibly in excess within the tube T and in the chamber 16C.
  • the operating point of micro-switches 18A and 18B, as well as the micro-switches themselves (but not the control rods end), are placed at a higher level compared to the water overflow height (N - Fig. 1), i.e. the highest level over which water can flow out from the tub 7 in case of a event of failure of the supply and dosage system, or of the solenoid valve 3.
  • micro-switches 18A and 18B are placed on a high position, the use of balls 17A and 17B with big dimensions (preferably a diameter in the order of 18-30 mm) and selection of rods 19A and 19B of a certain length, will let the live parts (i.e. the micro-switches themselves) to be spaced from the water supplied to the device 6, thus avoiding a likely contact of the overflow water from the tub 7 with them.
  • the operation point of the micro-switches may be advantageously raised further up, simply providing more than one ball inside each chamber 16A and/or 16B.
  • frictions determined by the ball configuration of both floats 17A and 17B in the respective flowing chambers 16A and 16B will be much smaller than that determined by substantially cylindrical or parallelepiped floats, used so far in known dosage devices, as explained initially; in this way, fault or jam-up risks are reduced; for the same reasons, the ball or spherical configuration of the floats according to the present invention ensures a consistent thrust on the micro-switch actuation rods.
  • the spherical structure also avoids possible alterations of the float external shape (the so-called "warping"), which may occur in the known devices due to their extended use.
  • a substantial advantage of a spherical configuration for the floats is their "self-cleaning" capability; in other words, during their motional steps, the ball floats tend naturally to rotate around their geometrical center and become free from likely soil deposits on them.
  • duct C3 and chamber 16C proves particularly advantageous for washing machines fitted with dynamic water intake systems.
  • the present invention can also be advantageously applied to machines fitted with a static intake system, i.e. where the washing pump starts operating only at the end of the liquid dosage step.
  • both the duct C3 and chamber 16C may not be strictly required, since there is no risk of a liquid level increase in the tub caused by any interruptions of the washing cycle.
  • a device for the liquid supply and dosage into the tub of a domestic washing-machine, particularly a dishwasher, where the liquid dosage is obtained through the detection of the level of the liquid being present within the tub; the device comprises detection means located outside the tub 7, which operate on the basis of the quantity of liquid supplied to the tub, a conduit being provided to let such detection means communicate with the tub.
  • closure means are provided to shut said conduit following the intervention of the detection means, or at the end of a liquid supply step to the tub, in order to prevent the substantial liquid back-flow from the tub to the detection means.
  • the detection means may comprise floats, which are apt to switch electric contacts for stopping the liquid supply to the tub, said floats being housed in respective chambers delimited in the body of the device; such a body is hydraulically connected to the tub, so that the gradual raising of the liquid level in the tub determines a consequent raising of a float in the respective chamber, which occurs gradually until producing the switching of a contact, the switching threshold of the contact corresponding to the achievement of a predetermined level of the liquid within the tub.
  • the float or floats used to this purpose preferably have a ball or spherical configuration.
  • the closure means comprise a non-return valve, particularly made of elastic material and/or actuated by the liquid itself.
  • vent means are provided which, also after the intervention of the detection means, are apt to allow the liquid return from the tub to said conduit, specifically in the instance of dynamic liquid supply systems.
  • vent means comprise at least a duct for constant connection of said conduit with the atmosphere, independently from the operating condition of said closure means, and a chamber delimited in the device body.

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  • Detail Structures Of Washing Machines And Dryers (AREA)
  • Main Body Construction Of Washing Machines And Laundry Dryers (AREA)
EP99110526A 1998-06-02 1999-06-01 Device for the liquid supply and dosage in a domestic washing machine tub, in particular a dishwashing machine Withdrawn EP0962182A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO980482 ITTO980482A1 (it) 1998-06-02 1998-06-02 Dispositivo per il caricamento ed il dosaggio di liquido nella vasca d i una macchina di lavaggio di uso domestico, in particolare una lavast
ITTO980482 1998-06-02

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EP0962182A1 true EP0962182A1 (en) 1999-12-08

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EP99110526A Withdrawn EP0962182A1 (en) 1998-06-02 1999-06-01 Device for the liquid supply and dosage in a domestic washing machine tub, in particular a dishwashing machine

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1059057A1 (en) * 1999-05-21 2000-12-13 SMEG S.p.A. Unidirectional shutter for level control systems in dishwasher machines

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH315864A (de) * 1954-07-31 1956-09-15 Verzinkerei Zug Ag Wasserstandüberwachungseinrichtung an Waschmaschine
US2882366A (en) * 1956-12-03 1959-04-14 Waste King Corp Dishwasher with float switch
GB2144031A (en) * 1983-07-27 1985-02-27 Bosch Siemens Hausgeraete Dishwashing machine
DE8512957U1 (de) * 1985-05-02 1985-06-13 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Geschirrspülmaschine mit einer Einrichtung zur Niveauregelung

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH315864A (de) * 1954-07-31 1956-09-15 Verzinkerei Zug Ag Wasserstandüberwachungseinrichtung an Waschmaschine
US2882366A (en) * 1956-12-03 1959-04-14 Waste King Corp Dishwasher with float switch
GB2144031A (en) * 1983-07-27 1985-02-27 Bosch Siemens Hausgeraete Dishwashing machine
DE8512957U1 (de) * 1985-05-02 1985-06-13 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Geschirrspülmaschine mit einer Einrichtung zur Niveauregelung

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1059057A1 (en) * 1999-05-21 2000-12-13 SMEG S.p.A. Unidirectional shutter for level control systems in dishwasher machines

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