EP0596302A1

EP0596302A1 - Washing machine with improved temperature regulation

Info

Publication number: EP0596302A1
Application number: EP93116725A
Authority: EP
Inventors: Maurizio Mori
Original assignee: Electrolux Zanussi Elettrodomestici SpA; Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1992-10-29
Filing date: 1993-10-15
Publication date: 1994-05-11
Also published as: ITPN920081A0; ITPN920081A1; IT1259233B

Abstract

A laundering or dishwashing machine, comprising a washing tub, a program control unit, electric circuitry connecting said program control unit to the various functional components of the machine, and a heater element for heating the washing liquid, and provided with means adapted to control the operation of the machine in cycles of different duration and at different operating temperatures, said cycle durations and operating temperatures being selectively and independently adjustable.

The different operating cycles include a long operating cycle, a regular operating cycle, and a short operating cycle.

Description

The invention relates to an improved type, particularly for domestic use, of a laundering or dishwashing machine provided with particular electric circuitry which, in association with timer of a specific type, permits various temperatures and various durations to be selected for individual operating phases without necessitating respective thermostats.
As the present description proceeds, specific reference will be made to a domestic laundry washer, it being understood, however, that the present invention is identically applicable also to a dishwashing machine.
Known laundry washers, particularly of the domestic type, make use of program control units in the form of electromechanic devices operable to control the functional components of the machine for the execution of all the required functions with the proper timing and in the correct sequence.
Known in particular are laundry washers provided with a so-called "thermogradual" system for regulating the temperature of the laundering liquid bath, and operable to attain one or several temperatures by energizing the heater element over one or several defined periods of time, by a suitable construction and arrangement of the electric circuitry and the program control unit.
As known, this solution does not permit to accurately attain the optimum temperatures for a determined cycle, inasmuch as the final temperature of the bath depends not only on the time the heater element is energized and the rated output of the heater element, but also on the initial temperature of the laundering liquid, which is unknown and may vary within rather wide limits.
This solution has nevertheless found wide-spread use in view of its functional simplicity, reliability and economy.
The actual tendency in the market towards the reduction of energy consumption, together with ongoing research aimed at always better satisfying the user's requirements, have directed attention to the desirability of making the laundering cycles more readily controllable and regulatable by the user, and have in particular shown up the desirability of disposing of laundering cycles permitting not only the laundering temperaturee to be selected from a number of predetermined tempertures, but also the individual duration of certain phases of the laundering cycle, including the individual heating phases.
It would therefore be desirable, and is in fact the object of the present invention, to provide a washing machine in which the advantages of the thermogradual operation are enhanced by the possibility of selecting, amongst a number of predetermined durations, the desired duration of certain phases of the cycle, and amongst a number of predetermined temperatures, the optimum temperature for any particular type of laundry.
In addition, this object should be attained without the necessity of a nearly totally new construction of the machine, so as to keep the production cost low and to not aggravate the complexity of the circuitry of the laundry washer as a whole.
This object is attained in a washing machine provided with circuitry of a particular construction and associated to a program control unit of a particular type as described in the appended claims.
The invention will be more fully understood from the following description, given by way of example with reference to the accompanying drawings, wherein:

fig. 1 is a diagrammatic illustration of the external controls of a machine according to the invention,
fig. 2 is a top plan view of control components of the machine of fig. 1 according to the invention, and
fig. 3 shows a diagram of the selected temperatures of the water in the tub of a machine according to the invention.

The solution devised by the invention basically consists in the combined use of:

a) a particular type of a program control unit provided with a first control component comprising a conventional program selector disc, and a second control component operable to select the speed of the cam disc stack amongst a discrete number of speeds, this second control component being preferably in the form of a second manually rotatable disc mechanically connected to a particular mechanical system of cams, lever transmissions, grear transmissions, reduction gears and other components integrated with the cam disc stack of the program control unit, and
b) electrical circuitry of the thermogradual type for the selection of the temperature of the laundering bath and associated to conventional circuitry for the control of the other components of the machine.

It is known that program control units of the type specified above have already been used for some time, for instance in certain types of combined domestic appliances for laundering and drying fabrics. Appliances of this kind employ a single program control unit provided with two selector controls in the form of rotatable discs, a first disc acting directly on the control unit for the selection in the conventional manner of the desired laundering cycle, and a second disc acting on determined mechanic components contained in the program control unit and operable to vary in a continuous manner the rotary speed of the cam disc stack during certain phases of the operating cycle.
When a laundry washer-dryer combination employing a program control unit of this type operates in the laundry drying mode, the control unit uses the same cams as employed for controlling the various phases of the laundering cycle, with the difference that these same cams now control the opening and closing of associated contacts at a different and regul-atable rhythm, permitting them to be employed for controlling the phases of the drying cycle known to require a different timing.
The invention is thus characterized by the use of these types of program control units provided with two selector controls, with the difference that the second selector control, rather than being employed for selecting the functions of the drying cycle, is used in the laundering mode, specifically for the purpose of varying in a discrete manner, i.e. in determined steps, the rotary speed of the cam disc stack for certain phases of the cycle, and thus the duration of the respective phases.
From what has just been explained, there appears a slight difference between the two types of program control units described; while in the case of the program control unit described in the first place, the second selector control is operable to vary the speed of the cam disc stack in a continuous manner, the program control unit described in second place permits the speed of the cam disc stack to be varied only in discrete steps.
This difference is irrelevant for the purposes of the present invention, inasmuch as the realization of a control unit of the second type, proceeding from a unit of the first typed lies within the facilities of one skilled in the art.
With reference to the figures of the drawings, there is shown the disc 1 of the main selector control 2 of the program control unit, and the disc 3 of the auxiliary selector control 4 operable to vary the duration of the various phases of the selected program.
The selector controls each comprise a rotatable shaft acting on a respective gear 5, 6, the two gears being interconnected by a third gear 7 meshing with both of them.
As shown in fig. 1, the temperature of 90° may be assigned to a so-called "regular" cycle, to a "long" cycle, or to a "short" cycle.
With reference to fig. 3, the temperature T₂ may assume different values, for instance the value of 60° or 90°, depending on the position to which the auxiliary temperature selector control 4 has been brought, the temperture T in specie indicating the temperature of the liquid in the tub during the various phases. In the example shown in fig. 3, the complete laundering cycle is composed of four distinct phases designated by A, B, C and D on the time scale, the phase A representing the interval during which a detergent is mixed with cold water, B representing the phase during which the laundering bath is heated, C representing the laundering phase at substantially constant temperature, and the phase D representing a succession of rinsing steps.
It is also noted that the individual phases are each composed of a number of time elements corresponding to the intervals during which the cam disc stack dwells at corresponding incremental positions.
A shown in fig. 3, phase A comprises only one time increment 1, phase B is composed of increments 2 to 7, and phase C is composed of increments 8 to 10. The rinsing phase D is not illustrated in detail, since it is not relevant in the context of the present invention.
Depending on the length of time and the temperature of the selected cycle, the invention provides that the various time increments are of variable duration, the attached Table A showing the complete succession of time increments for each cycle of a selected length, for each temperature, and for each phase.
In the case of a cycle at a selected temperature of 90°,Table B shows the overall duration of the individual phases A, B and C as determined from Table A in accordance with the type (length) of the selected cycle. The corresponding time intervals for a cycle at a selected temperature of 60° may be similarly derived from Table A.
From the above description there appears a further advantage of the invention, in that the laundry washing machine has been considerably simplified in the sense that the selector control of the program control unit is operable to solely select the type of the cycle in accordance with the type of fabrics to be treated, while the remaining variables (times and temperatures) can be directly selected by the user with a single separate selector control.
Any laundry washing machine or dishwasher may of course be designed with circuitry outlays and arrangements different from what has been described without thereby going beyond the scope of protection of the present invention.

Claims

1. A laundry washer or dishwashing machine comprising a washing tub, a program control unit, electric circuitry connecting said program control unit to the various functional components of the machine, and a heater element for heating the liquid of the washing bath,
characterized by being provided with means operable to cause the machine to operate with cycles of variable length and at variable operating temperatures, said cycle lengths and said temperatures being selectively and independently pre-adjustable.

2. A washing machine according to claim 1, characterized in that said variable-length cycles include a long-duration cycle, a regular-duration cycle, and a short-duration cycle.

3. A washing machine according to claim 2, characterized in that said variable operating temperatures are selectively pre-adjustable to each of said cycles and are defined by discrete values to be attained by energizing said heater element for determined periods of time.

4. A washing machine according to any of the preceding claims, characterized in that said means comprise a selector control operable to vary the speed of the cam disc stack of said program control unit during determined time increments.

5. A washing machine according to claim 4, characterized in that said selector control for varying the speed of the cam disc stack comprise an incrementally rotatable disc (4) projecting from the casing of the machine and associated to a reference scale (3) on the face of said casing, said rotatable disc being adjustable to a number of distinct positions each of which determines a unique and determined combination of cycle lengths and operating temperatures.

6. A washing machine according to claim 5, characterized in that said rotatable disc is connected to a specific cam of said program control unit (8) by one or more mutually meshing rotary elements (5, 6, 7).