GB2138451A - Distributor and safety valve assembly for washing machines - Google Patents

Abstract

A solenoid inlet valve 8 is connected to a manifold 6 by way of an inlet port 19 controlled by a valve 17 actuated by expansion of wax 13 when heated by a heating element 14 connected in parallel with the main inlet valve 8. Both inlet valves are connected to the pressure switch 21 of the washing machine so that if this switch remains closed or the main inlet valve 8 remains open for any reason, water inflow is cut off by the valve 17 which closes with a delay due to the thermal inertia of its operating mechanism. The manifold has multiple outlets 10 leading to respective washing additive reservoirs or to the washing receptacle and controlled by further wax-operated valves 17a. The embodiment of Figs. 3, 4 has no single electrothermal valve able to stop all inlet of water. <IMAGE>

Description

SPECIFICATION Distributor and safety valve assembly for washing machines This invention relates to a valve assembly for the distribution of water and anti-flooding, for washing machines.

In washing machines, the feeding water, before entering the washing receptacle, passes, sequentially, according to the washing cycle, through a certain number of reservoirs containing e.g.: detergent for prewashing; detergent for washing; a bleaching or whitening compound; a finishing compound. The number of said reservoirs and the contents of same, vary with the type of washing machine.

The sequence of the drawing of the various compounds from the respective reservoirs is established by the programming or timing device of the machine, while the water pipes leading to the various reservoirs may be fed by various systems.

The simplest system, which is relatively expensive, is to use a common manifold for the inflowing water, and as many solenoid valves as the number of reservoirs for the different compounds used in the cycle, each reservoir being connected to an out-flow duct connected to one of the solenoid valves, which are separately and sequentially excited through the programming device.

A second known system provides a single solenoid valve whose output enters a distribution slide valve whose movement is mechanically controlled by a cam connected to the programming device; the movement of said slide valve directs the water into a selected duct and each duct is connected to one of the reservoirs containing the different compounds used in the washing cycle.

This second system, while cheaper than the first is mechanically complex and therefore subject to trouble.

Electromagnetic valves, and level sensors, may not operate correctly, leading to flooding.

A first object of the invention is to provide a water distributing device, in keeping with the requirements of a washing machine with a washing cycle comprising sequential phases, which is reliable in operation and is cheap and easy to make.

Another object of the invention is to provide a water distributor device which is provided with a single solenoid valve and two security grades of anti-flooding which, as is known, can be caused by locking of the main solenoid inlet valve or of the level or pressure sensor provided for the control of the level of the water in the washing receptacle.

The device according to the invention is mainly characterized in that it associates a known electrical inlet valve for washing machines with an electrothermal valve which can intervene and close the water inlet to the machine, whether in the case of locking of the main inlet electromagnetic valve or in the case of failure of the level or pressure sensor to limit the level of the water.

By "an electrothermal valve" herein we mean a valve which is actuated by the thermal effects of an electric current. A particularly suitable form of electrothermal valve comprises a body of wax mechanically coupled to a valve member, and an electrical heating element, e.g. a heating resistor, embedded in or thermally coupled to the wax; when current is passed through the heating element it heats the wax which is thus made to expand and to move the valve member.

Such valves are described in our Italian patent application 67078-A/82. They are cheap, compact, quiet and reliable, and their thermal inertia can provide time-controlled operation.

Another particular feature of the device according to the invention derives from the fact that it comprises a water inflow chamber provided with as many outflow connectors as the number of reservoirs for the different compounds used in the washing cycle; each out-flow connector being controlled by a valve with electrothermal control of the aforesaid type.

The detailed particular features of embodiments of the invention device are described below with reference to the accompanying schematic drawings, by way of example only; in the drawings: Figure 1 illustrates a first embodiment of the device in partial longitudinal section, together with the electrical circuit for the connection to the water level sensor of a washing machine; Figure 2, on a larger scale, illustrates details of the end of an electrothermal valve; Figures 3 and 4 illustrate one of the intuitive structural variants of the device.

Fig. 1 shows a distributor and anti-flooding valve assembly 5 which comprises a hollow body 6 which is connected at 7 to a solenoid valve 8 connected at 9 to a water supply pipe. The body 6, defining a manifold chamber D, is provided with radial lateral branches 10, 1 ova, lOb... equal in number to the different reservoirs for the compounds which must be sequentially fed to complete the washing cyclce. An appendix 11 of the body 6 is provided with a cap 12 which forms a chamber containing wax 13 within which a thermistor 14 (PTC) is embedded and its electrical terminals 1 4a protrude outside the cap 12.

In the appendix 11 a bore contains a small hard rubber piston which acts as a seal for the wax 13 and as a thrust member for the stem 16 of a normally open inlet valve 17 which, against the reaction of a spring 18, can close the inlet port or seat 19 for the water entering chamber D, through the main inlet valve 8.

Each of the branches 10, 1 0a etc. contains a normally closed valve 1 7a, able to open a respective water passage 6a, 6b which feeds the respective connector; 14a, 14b indicate internal or external thermistors for heating the wax masses contained in the respective chambers forming part of the outlet valves 17a.

20 indicates schematically the water pressure or level sensor of the washing machine and 21 is the electrical switch of the said sensor, which is normally closed and is opened by the water pressure when the water level C in the washing receptacle reaches a pre-established limit.

A and B indicate the electrical mains terminals and 22 indicates the electrical switches (transistors or mechanical switches) actuated by the programming or "timer" device of the machine.

The operation of valves 17, 17a is effected by passing current through their heating resistors 14, 14a .... thereby expanding the wax and causing it to move the valve members; when the current is cut off the wax contracts and the valve springs 18 move the valve members in the opposite direction With the washing machine operating, the programming device closes the switches 23, 24....less one and thereby energises the respective thermistors 14a, 14b....which causes the heating and the expansion of the wax and thereby the opening of valve 17a or 1 7b. . . so that the corresponding branch 10, 1 Oa....

communicates with the reservoir for the compound which has to be mixed with the water in that cycle phase.

From Fig. 1 it can be seen that the solenoid valve 8 and the thermistor 14 of valve 17 (with the switch closed) are fed in parallel.

The wax 13 has a melting point and an expansion coefficient so selected that the time needed to close the valve 17 onto the seat 19 is a little greater than the time required to fill the washing receptacle, in the worst conditions of the pressure and the delivery capacity of the water supply network.

In the normal operating condition, before the closure of seat 19 by the valve 17, the water level C causes the opening of the switch 21 and the consequent interruption of the electrical supply to valve 8 which closes and stops the inflowing water.

The opening of switch 21 also cuts off the thermistors 14 wherefore the wax cools and the valve 17, due to the reaction of spring 18, returns to its fully open position.

If, for any cause, the switch contacts 21 remain stuck or the sensor 20 does not operate, the thermistor 14 remains energised and, consequently, the expansion of the wax 13 causes the closing of seat 19 by the valve 17 and the cessation of the water inflow into the manifold and hence into the washing receptacle. Similarly, the valve 17 cuts off the water in the case of locking of the sensor 20-21 and/or of the valve 8.

As shown in Fig. 2 the valve stem 16 is inserted within a hollow seat 26 in valve 17.

with the intermediary of a resilient member 27, in order to increase the longitudinal stroke of stem 16, with the valve closed, without any excessive thrust of the valve member against the valve seat.

In the structural variant represented in Fig.

3, the valve group 13,14,15, 16 and 17 represented on Fig. 1 is omitted, as it has been experimentally proved that all the valves 10, 1 Oa, 1 Ob, 1 Oc....are perfectly capable to control the water flow within the pressure operating values expected for washing machines.

In Fig. 3, the various outlet valve units are joined to body 6 by welds 28, preferably ultrasonic welds. In the variant represented in Fig. 4 the valve units are radially inserted and fixed to the body 6 by means of screws 19.

The outlet valve units have locating skirts, and are alsigned along the manifold on its underside.

The various water passageways, including those controlled by the electrothermal valves 17, 17a....should have a large cross-section so as to cause minimal pressure losses.

Details of the illustrated electrothermal valves are shown in Figs. 5 and 6 in which the reference numerals have the following meanings: 10, 11-valve body; 1-valve seat; 2-screw connector for water supply; 3-outlet union; Y-water flow; 4-filter; 12-cap; 13-wax-filled chamber; 14-heating thermistor (PTC); 14a-electrical terminals; 15-piston; 16-valve stem; 17-valve member; 18-valve return spring; 30-valve washer.

Since the heating resistors or thermistors have positive temperature coefficients, in operation they heat up to a stable characteristic temperature at which they heat the wax safely.

The valve assembly is preferably made of plastics, e.g. injection or pressure moulded plastics.

Any structure and shape of the device according to the invention offers in its use the following advantages: - a compact assembly contained within limited dimensions because the valves 10, 1 Oa. . . providing the water flow distribution are arranged radially with respect to body 6, opportunely angled to one another, occupying therefore a limited space; ~the reliable operation of the device by the time deriving from the valve type used with electrothermal control; the total absence of vibrations and noise deriving from the non-use of magnetic members; ~the low cost of the device, remarkably reduced (- 30% less) with respect to the cost of analogous conventional devices.

Claims (7)

1. t. A distributor and safety valve assembly for a washing machine comprising an electrically operated main inlet valve and a water manifold downstream thereof, characterised in that the manifold has a water entry port and a normally open inlet valve is provided for closing the entry part when energised, the latter valve being an electrothermal valve (as herein defined) connected in parallel with the water inlet valve and having a closing time longer than the normal filling time of the washing machine, and in that the manifold is provided with a plurality of lateral outlets and normally closed electrothermal outlet valves controlling these outlets for operation by a programming device of the washing machine.
2. 2. A valve assembly as claimed in claim 1 in which the outlet valves are disposed radially relative to the manifold.
3. 3. A valve assembly as claimed in claim 2 in which the outlet valves are longitudinally aligned along the manifold.
4. 4. A valve assembly according to Claim 1 wherein the outlet valves are anyhow oriented with respect to the skirt of same.
5. 5. A valve assembly according to Claim 1, modified in that one electrically operated pressure unbalance valve admits directly into a manifold provided with a plurality of normally closed radial outlet valves which can be controlled for opening by the electrical energisation of a thermistor embedded in a wax chamber, for each outlet valve.
6. 6. A valve assembly according to any of the preceding claims, characterized in that the water passageways, controlled by the electrothermal valves have a large cross section allowing a minimum of pressure losses.
7. 7. A valve assembly according to any of the preceding Claims, pressed with a suitable plastic material, wherein the valve bodies corresponding to as many downflow connectors, are attached to the manifold by embedding and ultrasonic welding.