The present invention refers to an improved laundry washing machine.
It is known how electric appliance manufacturers have made efforts to make laundry washing machines that afford a modest consumption of energy, water and detergents.
As far as the containment of detergent consumption is concerned, a source of waste of the same is to be attributed to the fact that, at the moment of loading the detergent, a part of it, not dissolved, deposits in the discharge tube or in the filter of the washing machine; in this zone the detergent cannot be utilized, hence it is wasted.
There are know on the market washing machines designed to reduce the consumption of detergents, exploiting systems that can be substantially broken down into three categories.
A first category of said systems includes a pump for the forced recirculation of the washing liquid during the operative cycle of the washing machine.
A second category provides for the addition of a shut-off valve on the discharge tube of the wash tank.
A third category provides for the addition of a supplementary tube for the recirculation of the washing liquid, recirculation that is determined by the movement of the basket during washing.
As can be inferred, all the know systems for saving detergent require an addition of components besides the ones normally provided.
From GB-A-1 020.085 a laundry washing machine is also known, having the features listed in the preamble of annexed claim 1; in this known machine, a water supply pipe to a detergent container is provided with a change-over valve, adapted to by-pass water for the washing process through a feed pipe into the washing tank, said pipe being preferably arranged for leading directly into the outlet of the tank itself. In this way, detergent being subsequently conveyed with water from the container to the tank cannot enter the drain outlet of the latter, which results in being already filled with water.
In view of the state of the technique described, the object of the present invention is to provide a laundry washing machines that permits to keep down the consumption of detergents without requiring the installation of further components in the machine.
In accordance with the present invention, such an object has been achieved by a laundry washing machine having the characterizing features of the annexed claim 1.
Thanks to the present invention a detergent savings is achieved, due to the fact that in the pre-filling step of (clean) water only the discharge tube is filled, and during the successive water and detergent loading step - given that the basket is kept in rotation, preferably in one direction - the detergent is kept as far away from the discharge tube as possible, so as to present the detergent itself, not yet dissolved in the water, from precipitating into the discharge tube.
These and other features of the present invention will be rendered more evident by the following detailed description of an embodiment thereof, illustrated as a non-limiting example in the attached drawings, in which:
In Figure 1 a washing machine is schematically shown in section view according to a vertical plane. The washing machine comprises a washing tank 1, inside which a rotatable basket 2 is lodged, rotated by a motor 3. Tank 1 has an inlet tube 4 with an upper part connected to a detergent dispenser 5, and an outlet tube 6 connected, at one end, with the bottom of the tank 1 and, at the other end, to a discharge pump 7.
The inside of the detergent dispenser comprises a number of compartments 8A, 8B, 8C separated from each other. To each compartment is associated a respective derivation 9A, 9B, 9C of a clean water supply duct 9. Between each of the derivations 9A, 9B, 9C and the duct 9 is interposed a respective intercepting valve 10A, 10B, 10C individually controlled by a control unit 11, for example composed of a timer normally included in the known washing machines. Timer 11 also controls the activation of motor 3.
As is visible in the Figures, the first compartment 8A of the detergent dispenser 5 is empty, while in the second compartment 8B the detergent (typically in powder form) is loaded. The third compartment 8C can, for example, contain a softener to be employed during the rinsing step.
The washing process carried out by the laundry machine according to the present invention comprises a first step during which valve 10A associated with the first compartment 8A of the detergent dispenser (the empty one) is opened so as to load a pre-established quantity of clean water, which determines a pre-filling of the discharge duct 6 and also, partially, of tank 1. In this first step, the basket can be left still. The duration of this step depends on the quantity of water that one may want to pre-load into the washing tank.
In the second step of the washing cycle, valve 10A is shut off and valve 10B associated with the second compartment 8B of dispenser 5 (the one containing powdered detergent) is opened. Moreover, in this step, timer 11 commands the activation of motor 3 to bring about the rotation of the basket 2 (in the example, clockwise). The water coming from derivation 9B of the duct 9 passes into compartment 8B, draws out the detergent and carries it into tank 1 where the water with the detergent can pass into basket 2 through holes normally provided in the walls of the same. In this step, the detergent is not completely dissolved yet. Nevertheless, thanks to the fact that the discharge tube 6 was pre-filled before and that the basket rotates, it is possible to avoid that the particles of detergent still in a solid state can precipitate into the discharge tube 6, where it would remain useless and wasted.
It is to be pointed out that the quantity of water that is loaded in the pre-filling step of the tank, the position of inlet tube 4, the position of discharge tube 6, and the direction of rotation of the basket during the water loading step (with detergent added) must be determined in such a way that the solid detergent which descends into the tank together with the water remains substantially all inside the tank itself and is not allowed to descend into the dead zones (discharge tube) connected to the tank.