Protective tray for washing machine

Abstract

 The invention relates to a protective tray (2) for a washing machine, which is suitable for post-installing under the washing machine (1). The protective tray has a plastic bottom (11) and plastic sidewalls (12) and an internal water alarm (3) having at least a power supply, a sensor for detecting the presence of water and an audible signal device which is connected to give an audible alarm when said sensor is in contact with water.

Description

[0001] The invention relates to a protective tray for a washing machine which is suitable for post-installing under the washing machine and which comprises a bottom and sidewalls and inside the tray a water alarm having at least a power supply, a sensor for detecting the presence of water and an audible signal device and/or discharge pump connected to the drain, which is/are connected to act when said sensor is in contact with water.

[0002] Washing machines in general, but particularly dish washing machines, which are normally located in kitchen spaces without floor drains, nowadays cause a considerable part of the water damage occurring in dwellings. Laundry washing machines also cause this damage, albeit somewhat less, since they are normally located in spaces with floor drains, such as bathrooms or utility rooms. Water damage can be sudden and severe, if the inlet water hose of the washing machine becomes detached or ruptures or if for any reason the solenoid valve of the washing machine itself does not close properly. Water damage can also arise gradually in the course of time if the hoses or valves leak. In all these cases the water damage and costs associated therewith can be at least substantially reduced if the occupant closes the manually operated shut-off valve, which is obligatory in the pressure water line, immediately the aforesaid sudden, severe leakage starts as well as always when the washing machine is not in use.

[0003] Publication US 4,814,752 describes a tray on top of which the washing machine is situated and which is capable of collecting and holding overflow water. Additionally in the tray is a float, which upon a rise in the water level cuts the power to the washing machine by an electrical switch. The device further has an audible signal device to alert personnel. The problem of this construction is firstly that it is slow acting because the action of the float, i.e. cutting the electrical power, can occur only after a considerable rise in the water level has occurred, which in many cases is too late. A second problem is that the construction is not capable of providing any protection against water leakage in cases where overflow is caused by a faulty solenoid valve, i.e. failure of the solenoid valve to close, or by rupture of the inlet water hose.

[0004] Publication US 4,903,723 describes a tray for location under a washing machine to collect leakage water, the base of which tray is formed of an inclined major part leading to a minor horizontal section at the rear of the tray where is arranged either a downward oriented drain assembly or the inlet tube of a drainage pump. The drainage pump is also connected by conductors to a moisture sensor as well as a power conductor to start the pump and possible audible alarm. The tray is glued to the floor before installation of the washing machine and thereafter the washing machine is pushed into place over flanges extending outwardly from the sides of the tray. This installation work is very inconvenient and requires a professional. Additionally the tray is smaller than the washing machine and thus leakage water can run down the sides of the body of the washing machine outside the tray, so that the security and benefits of the solution described are questionable.

[0005] An object of the invention is to achieve a device by which water damage arising in connection with dish washing machines, laundry washing machines and other similar water-using appliances which at times operate automatically, i.e. without the occupant, and which have standard external dimensions can be minimized or at least said water damage can be limited so as to be as little as possible and moderate in respect of repair costs. A second object of the invention is a version of such a device that can be installed if necessary by a layperson as well as a version that operates automatically, i.e. independently, to minimize possible water damage. A third object of the invention is such a device which is reliable in operation and durable, but at the same time of a price so low as to be inconsequential for the occupant or user of the washing machine in relation to the reduced risk of damage.

[0006] The problems described above are diminished and the objects defined above are accomplished by a protective tray according to the invention, which is characterized by that which is defined in the characterization section of Claim 1.

[0007] The principal advantage of the invention is that the protective tray of the invention provides an alarm both for minor leakages, giving the occupant the opportunity to repair the washing machine or have it repaired or correct its settings in time before the building structure has suffered major damp damage, and also for sudden major leakages, informing the occupant of the leakage immediately it occurs so that the occupant can quickly close the obligatory stop valve and/or undertake other steps to limit the extent of water damage. A second advantage of the invention is that the protective tray of the invention is in its simplest form an insignificant price compared with that of a washing machine and does not require the employment of an outside installer. An additional advantage, however, is that the protective efficacy of the protective tray can be further considerably enhanced, although then in most cases it is necessary to use a professional installation firm and the price too is somewhat higher. Thus various levels of security are offered for the user.

[0008] In the following the invention is explained with reference to the accompanying drawing.

[0009] Fig. 1 represents a protective tray for post-fitting according to the invention located under a washing machine, as seen from outside in an axonometric view. The water alarm is shown in the Figure together with various possible implementations of its power supply.

[0010] Fig. 2 shows a more versatile embodiment of the water alarm of the protective tray according to the invention, comprising both a magnetically operated closing valve and a drainage pump for the protective tray.

[0011] Fig. 3 shows a simple embodiment of the water alarm of the protective tray according to the invention and its mechanical construction in a cross-section along the vertical place I-I of Fig. 1.

[0012] Figs. 4A - 4D show sensors of various types which react to the presence of water for use in the water alarm of the protective tray according to the invention.

[0013] The invention thus relates to a protective tray or protective tray assembly for a washing machine, such as in particular a dish washing machine, but also a laundry washing machine or other similar appliance. The protective tray 2 according to the invention is preferably a single piece and typically consists of plastics. Naturally nothing prevents the manufacture of the protective tray from other material, such as metal, or from plastic by other manufacturing technique, such as from sheet plastics by welding or gluing. The protective tray 2 has a bottom 11 and sidewalls 12 forming a sealed, continuous construction, which is so dimensioned that the protective tray is suitable to be post-installed under a washing machine 1, i.e. after the initial installation of the washing machine. For this purpose the horizontal dimensions W2, D2 of the protective tray correspond to the horizontal dimensions W1, D1 of the washing machine. Explicitly, the horizontal dimensions W2 and D2 of the tray are as close as possible, for example, to the horizontal dimensions of the space reserved for a dish washing machine in a row of cupboards. In this case the dimensions W1 and D1 of the washing machine fit within the external dimensions of the protective tray or at most the external dimensions of the washing machine are equal to the external dimensions of the tray. The height H of the sidewalls 12 of the protective tray 2 is dimensioned to correspond to the water volume of at least one load of the washing machine or preferably the water volume of two loads of the washing machine or even more if space allows. The occupant then has some time margin in which to react to the alarm given by the device of the invention. The bottom 11 of the protective tray is essentially flat or planar at least for its lower surface 27a, so that said bottom 11 rests firmly upon the floor surface, whereon the weight G of the washing machine is transmitted through the bottom 11 to the floor surface 30. Preferably also the upper surface 27b of the bottom 11 is at least mainly flat or planar, so that the supporting legs 31 of the washing machine are well supported on it. In the above flat is to be understood as meaning that the bottom has a lower surface 27a and/or an upper surface 27b that acts as a flat surface, but that the actual lower surface and upper surface may consist, for example, of stiffening ribbing which effectively forms a plane even though the bottom part which achieves watertightness may deviate even considerably from a plane.

[0014] In particular inside the protective tray 2 of the invention is a water alarm 3, comprising at least a power supply 7, a sensor 6 for detecting the presence of water and an audible signal device 8. The audible signal device 8 is connected to the sensor 6 and the power supply 7 in such a manner that the assembly gives an audible alarm when said sensor is in contact with water V. A simple water alarm of this type is represented in Fig. 3 and in this case the water alarm 3 is a separate component 3a for placement on the bottom 11 of the protective tray 2. The said water alarm 3 has a body preferably having a downwards convex uninterrupted cover 9, without openings like an inverted cup, comprising of an upper part 25a and downwards oriented edges 25b, which design protects the electrical components from possible leakage water running down on top of them. The audible alarm device 8, power supply 7 and possible other electronics 4 of the water alarm 3, which can be connected to a circuit board 26 or alternatively directly to the lower surface of the cover 9 e.g. in depressions cast into the plastic part, are arranged in the upper part of the inside of the cover, for example against said upper part 25a, so that they remain operational for as long as possible when the protective tray fills with water V. Because the height of the space under different makes of washing machine 1 may vary, it is preferable to make the cover 9 moveable or adjustable in the vertical direction P, so that the audible signal device 8, power supply 7 and possible other electronics 4 can in each individual application be set as high as the space permits, so that they become immersed in water as late as possible. The sensor 6, on the other hand, is arranged in the lower part of said water alarm so as to be placed at a point approaching the upper surface 27b of the bottom 11 inside the tray. As can be seen from Fig. 3, the sensor can be located for example on the surface of the base flange 22 which forms the lowest point of the body of the water alarm 3, in which case it can detect water V coming into the protective tray as soon as the water has risen above the thickness of said base flange, i.e. when the depth of water is 3 mm - 10 mm.

[0015] The water alarm 3 may alternative be a component 3b integrated into the protective tray 2, as is shown by broken lines in Fig. 1. In this case the water alarm 3 preferably has all the same features as the water alarm 3a, which forms a separate component. In other words, the water alarm has the features presented in this description regardless of whether it is a separate component 3a or an integrated component 3b. The body of the separate water alarm 3 represented in Fig. 3 also includes a lower part which comprises a relative wide base flange 22, upon which the water alarm stands freely, upwardly oriented edges 23, over which the downwards oriented edges 25b of cover 9 extend. Additionally in the edges 23 of said lower part are holes or slits 24 rising upwards from the base flange 22, which allow water V that has run into the tray on its bottom 11 to flow into the water alarm and further to the sensor 6.

[0016] The power supply 7 may be either a battery or a safety-insulated power supply for insertion into a mains socket outlet 5. A battery can be located on the front sidewall 12 of the protective tray and connected by a conductor to other parts of the water alarm, as shown by a broken line in Fig. 1, or can be located in the water alarm 3 itself, as shown in Fig. 3. The purpose is to make replacement of the battery as easy and rapid an operation as possible. If desired the water alarm can be arranged with an additional alarm to alert the occupant to the need to replace the battery. A safety-insulated mains power supply is always used when the water alarm according to the invention comprises a solenoid-operated closing valve 13 and/or discharge pump 10, as described below, since they require so much electrical power that for operational reliability it would perhaps not be possible to rely entirely on a battery or it would be necessary to use several large-size batteries.

[0017] The audible signal device 8 is advantageously a piezoelectric buzzer, because it is advantageous in price and using it a loud sound is obtained easily and with relatively low current. By suitably shaping and dimensioning the previously described cover 9 it can be made to resonate at the frequency of the piezoelectric element, which reinforces the audible signal. It is also possible to arrange suitable electronics 4 in the water alarm and to connect it to the occupant's telephone line, so that the device calls and sends an alarm to the occupant's mobile telephone. Such sending of an alarm to the occupant's mobile telephone can also be arranged using so-called Blue Tooth technology, which is known per se.

[0018] The sensor 6 of the water alarm 3 is advantageously of a type, which detects water either by a change of capacitance ΔL between electrodes 19 or by a change of electrical resistance ΔR. The principle of a sensor detecting change of capacity ΔL is shown in Fig. 4b, in which a capacitance L is formed by electrodes 19 which are inside insulating plastics with a gap 18 between them, whereon the capacitance changes when water V enters said gap 18 and replaces air. The change of electrical resistance ΔR in sensor 6 may be caused firstly by a change from air to water V in a gap 18 between bare metal electrodes 17 in the sensor of Fig. 4A, because the electrical conductivity of both pure tap water and of used washing water is considerably greater than that of air. The water thus "short circuits" electrodes 17. Secondly, the change of electrical resistance ΔR in sensor 6 may be caused by the greater thermal conductivity of water compared to that of air surrounding a resistive element 20; a solution of this type is represented in Fig. 4C, in which a so called NTC (Negative Temperature Coefficient) or PTC (Positive Temperature Coefficient) resistor 20 is used as the sensor 6. A continuous electrical current passes through a sensor of this type keeping its internal temperature at a certain value and its ohmic resistance R at a certain value while it is surrounded by air, but when the surrounding medium changes to water, which conducts heat away from the resistor 20, the internal temperature of said resistor changes and thus also its ohmic resistance. Thirdly, the change of electrical resistance ΔR in sensor 6 may be caused by contact occurring between electrodes 21 upon water eliminating a material 16 holding said electrodes apart. A sensor of this type is shown in Fig. 4D, in which the electrodes 21 are formed as springs, the force of which attempts to bring said electrodes into mutual contact, but while dry this is prevented by a piece 16 which is electrically insulating but water soluble. When water V comes between electrodes 21, piece 16 is dissolved away, whereupon under influence of their spring force said electrodes press against each other creating a short circuit between them. By suitable dimensioning all embodiments of sensor 6 other than that based on change of capacitance ΔL can be made to function without additional electronics 4 as a sufficiently good switch to produce a short circuit between the power supply 7 and the audible signal device 8. The additional electronics 4, however, are very simple and known per se, and so will not be explained in more detail here.

[0019] The protective tray 2 may additionally comprise a discharge pump 10 connected to a drain and/or a solenoid-operated closing valve 13 arranged in the inlet water hose 14 of the washing machine. The discharge pump 10, which is started by the water alarm 3 when the water alarm has come into contact with water V in the manner described, is located on the bottom 11 of the tray and its outlet tube 15 is connected in some usual manner to a drain. The solenoid-operated closing valve 13, which is closed by the water alarm 3 when the water alarm has come into contact with water V in the manner described, is preferably fitted between the fixed water supply pipe 28 and the inlet water hose 14 of the washing machine 1. The protective tray 2 may additionally comprise a flexible protective hose 29 surrounding the inlet water hose 14 of the washing machine, the lower end of which protective hose is open to the bottom 11 of the protective tray thereby conducting water leaking from a ruptured inlet water hose into the protective tray to give an alarm.

Claims

1. A protective tray for a washing machine, which is suitable for post-installing under the washing machine (1) and which comprises a bottom (11) and sidewalls (12) and inside said tray a water alarm (3) having at least a power supply (7), a sensor (6) for detecting the presence of water and an audible signal device (8) and/or a discharge pump (10) connected to a drain, which is/are connected to act when said sensor is in contact with water (V), characterized in that said bottom (11) comprises at least a lower surface (27a) providing an essentially flat support surface, whereupon the weight (G) of the washing machine is transmitted through the bottom to a floor surface (30); that said sidewalls have a height (H) dimensioned to correspond to the water volume of at least one load of the washing machine; and that said protective tray (2) further comprises a protective hose (29) surrounding the inlet water hose (14) of the washing machine, the lower end of which protective hose is open onto the bottom (11) of the protective tray.

2. A protective tray according to Claim 1, characterized in that said protective tray has horizontal dimensions (W2, D2) corresponding to horizontal dimensions (W1, D1) of the washing machine; and that the bottom (11) and sidewalls (12) of said tray are plastic.

3. A protective tray according to Claim 1, characterized in that the water alarm (3) is a separate component (3a) for placement on the bottom of the protective tray (2) or alternatively a component (3b) integrated into said tray.

4. A protective tray according to Claim 1, characterized in that the power supply (7) is either a battery or a safety-insulated power supply for insertion into a mains socket outlet (5).

5. A protective tray according to Claim 1, characterized in that the audible signal device (8) is a piezoelectric buzzer; and that said sensor (6) is a type, which detects water either by a change of capacitance (ΔL) between electrodes (19) or by a change of electrical resistance (ΔR).

6. A protective tray according to Claim 5, characterized in that the sensor (6) is a type in which the change of electrical resistance (ΔR) is caused by:

- a changing of air to water between electrodes (17); or

- a greater thermal conductivity of water compared to that of air surrounding a resistive element (20); or

- a contact occurring between electrodes (21) upon water eliminating a material (16) holding said electrodes apart.

7. A protective tray according to any of the preceding Claims, characterized in that said water alarm (3) has a downwards convex uninterrupted cover (9), inside the upper part of which said audible signal device (8), said power supply (7) and possible further electronics (4) are arranged; that said sensor (6) is arranged in the lower part of said water alarm so as to be placed at a point approaching an upper surface (27b) of the bottom (11) inside the tray; and that the cover is adjustable in a vertical direction (P).

8. A protective tray according to any of the preceding Claims, characterized in that it further comprises a solenoid-operated closing valve (13) arranged in the inlet water hose (14) of the washing machine.

Drawing