EP0118167A2

EP0118167A2 - Improvements in or relating to washing machines

Info

Publication number: EP0118167A2
Application number: EP84300231A
Authority: EP
Inventors: Stewart Christie
Original assignee: Thorn EMI Domestic Appliances Ltd
Current assignee: Thorn EMI Domestic Appliances Ltd
Priority date: 1983-02-24
Filing date: 1984-01-16
Publication date: 1984-09-12
Also published as: EP0118167A3; GB8305194D0

Abstract

A washing machine 1 contains water level sensors 3, in a drum 2, which has a water inlet 10. A hot water supply 6 and a cold water supply 7 are connected respectively to the inlet 10. The operation of valves 11, 12 for disconnecting and connecting the supplies 6, 7 to the inlet 10 is governed by a processor 14, in accordance with the water temperature at the inlet 10, which is sensed by temperature sensor 13.

In another aspect of the invention, the processor 14 renders a door catch inoperable when the drum 2 is full of water, provides an indication to the user that the door catch has been rendered inoperable, and initiates a draining cycle to drain the water from the drum 2 before automatically opening the door.

Description

This, invention relates to washing machines.
Washing machines, having various user-selective wash programs for different types of fabrics, different colours, etc. of the items to be washed, are well known. It is also generally known that a maximum temperature of the water for each particular type of program has been standardised by certain regulations to ensure that the items being washed are not damaged by over-hot water.
The usual procedure for maintaining these regulated standards for the temperature of the water is by filling the washing machine with cold water, for low temperature wash programs, and then heating it in the machine to,the required temperature, or by filling the machine with relatively hot water,,for high temperature wash programs (ie. greater than approximately 60°C), and then further heating the water in the machine to the required temperature.
Although this procedure does normally ensure that the maximum temperature for the particular wash program is not exceeded, it does however require a substantial amount of energy to heat the water to the required temperature within the washing machine.
Problems may also arise in known washing machines when the door of the machine is required to be opened during the cycle of a wash program. Usually the door is provided with a safety lock to prevent it from being opened mid-cycle when the machine is filled with water, so that it is necessary to wait until the complete cycle has finished before the door can be opened.
It is therefore an object of the present invention to provide a substantially improved washing machine to those that have been provided heretofore.
According to one aspect of the present invention there is provided a washing machine having a water inlet connected to a supply of hot water and a supply of cold water, temperature sensing means for sensing the temperature of water substantially at the water inlet, and processor means for causing connection and disconnection of said supplies to the water inlet, in dependence on the temperature of the water sensed by the temperature sensing means, thereby providing regulation of the temperature of the water entering the washing machine.
The machine preferably includes water level sensing means, the processor means being arranged to disconnect both supplies to the water inlet when the water level sensing means indicates that the machine contains a desired amount of water.
According to another aspect of the invention there is provided a washing machine including water level sensing means, user-operable means for opening a door of the machine, and processor means for controlling operation of said user-operable means in accordance with an output from said water level sensing means, so as to render said user-operable means inoperable when the output indicates a relatively high water level, to initiate draining of the water from the machine, and to provide an indication to the user that said user-operable means are operable when said output indicates that the machine is substantially empty of water.
There is preferably provided a further indication to the user when the user-operable means is rendered inoperable.
It is also preferable that the first-mentioned indication. comprises automatic opening of the door, provided by the processor means, when said output indicates that the machine is substantially empty of water.
The invention will now be further described by way of example only with reference to the accompanying drawings, wherein:

Figure 1 shows a schematic view of an embediment in accordance with one aspect of the invention.
Figure 2 shows a flow-chart of a sequence of operations thereof.
Figure 3 shows a schematic view of an embodiment in accordance with a second aspect of the invention,
Figure 4 shows a flow-chart of a sequence of operations thereof, and
Figures 5 to 7 show a flow-chart of a typical complete wash program suitable for a washing machine, in accordance with the present invention.

Referring to figures 1 and 2, a washing machine is shown generally at 1, including a drum 2 into which items (not shown) to be washed are placed. Water level sensors 3 and 4 consist of switches which are tripped by water level 5 within the drum 2.
A hot water supply 6 and a cold water supply 7 are connected respectively by pipes 8 and 9 to a water inlet 10 to the drum 2. Hot water supply 6 and cold water supply 7 can be disconnected or connected to the water inlet 10 by operation of valves 11 and 12, respectively.
A temperature sensor 13, which is preferably a thermister, is situated in the region of the water inlet 10, so that it senses the temperature of water entering the inlet 10 and generates an analogue output indicative thereof.
The sequence of operations is governed by a processor 14, so that, at the beginning of a particular wash program when the drum 2 is required to be filled with water at a particular temperature, processor 14 firstly opens valve 11 to connect the hot water supply 6 to the water inlet 10.
If level switch 4 has tripped, then this is an indication that the drum 2 is already full of water and consequently the processor 14 closes valve 11 again. However, if the level switch 4 has not tripped, then the analogue output from the temperature sensor 13 is fed to the processor 14, to indicate thereto the temperature of the water at the inlet 10. If the water level is not too hot for the particular wash program required, then level switch 4 is checked again to ascertain whether it has tripped.
If, however, the water is too hot, then processor 14 closes hot water valve 11 and opens cold water valve 12. Level switch 4 is again checked, and if it has tripped, cold water valve 12 is closed again. If it has not tripped, cold water valve 12 is left open for a period of four seconds, after which time it is closed again and hot water valve 11 is re-opened. This complete sequence of operations can then be repeated, until level switch 4 is eventually tripped, thereby indicating that the drum 2 is full of water, when both valves 11 and 12 are closed.
It can thus be envisaged that, by repetition of this sequence of operations, the temperature of the water at inlet 10 can be regulated in accordance with the required temperature for that particular wash program, so that, as soon as the water approaches a temperature determined by the selected programme, the hot water supply 6 is disconnected and the cold water supply 7 is connected for a period of four seconds, so as to prevent excessive use of relays.
This aspect of the invention therefore provides optimum use of available hot water, thereby saving energy by obviating or at least reducing the need to heat the water once it is actually in the drum 2.
Referring now to figures 3 and 4, in which like parts in figure 3 are labelled with like reference numerals with respect to figure 1, a door catch 16 for a door (not shown) of the machine 1 is operated by a button 15, which is pressed by a user of the machine to open the door.
When the user presses button 15, the processor 14 checks whether level switch 3 has tripped. If it has not tripped, this means that the drum 2 is substantially empty of water, and consequently the door catch 16 may be opened.
If, however, level switch 3 has tripped, the processor 14 renders the door catch 16 inoperable, so that it cannot be opened when button 15 is pressed by the user. The processor 14 then provides an audible indication, such as a bleeping sound, to the user to indicate that the door catch 16 cannot be opened, and also illuminates an LED 17 to indicate that the processor 14 has registered the fact that the user wishes to open the door catch 16.
The processor 14 then initiates a draining cycle to drain the water from the drum 2 through outlet 18 by opening valve 19, level switch 3 being continuously checked to ascertain whether it has tripped, thereby indicating that the drum 2 is substantially empty of water. Once level switch 3 has tripped, the door catch 16 is opened automatically by the processor 14.
It can therefore be seen that the present invention also provides means whereby a wash program can be interrupted and the water drained, so that the door can be opened any time during a wash program without any risk of flooding.
Instead of using switches for the water level sensors, a capacitive presure sensor may be utilised, which provides an analogue output in dependence on the rate of change of water level.
A typical complete wash program suitable for a washing machine, in accordance with the present invention, is shown in Figures 5 to 7, wherein T represents the temperature of the water in the washing machine drum and T_set represents the set required temperature of the water for the particular wash program selected by a user of the machine.
Alternative sequences of operation in accordance with the invention will, of course, be envisaged by persons of ordinary skill in the art.

Claims

1. A washing machine (1) having a water inlet (10) connected to a supply (6) of hot water and a supply (7) of cold water, characterised in that said machine (1) includes temperature sensing means (13) for sensing the temperature of water substantially at the water inlet (10), and processor means (14) for causing connection and disconnection of said supplies (6, 7) to the water inlet (10), in dependence on the temperature of the water sensed by the temperature sensing means (13), thereby providing regulation of the temperature of the water entering the washing machine.

2. A washing machine as claimed in claim 1 and including water level sensing means (3, 4).

3. A washing machine as claimed in claim 2 wherein the processor means (14) is arranged to disconnect both supplies (6, 7) to the water inlet (10) when the water level sensing means (3, 4) indicates that the machine (1) contains a desired amount of water.

4. A washing machine as claimed in claim 2 or 3 wherein said water level sensing means (3, 4) consists of a switching device.

5. A washing machine as claimed in claim 2 or 3 wherein said water level sensing means (3, 4) consists of a capacitive pressure sensor.

6. A washing machine (1) including water level sensing means (3, 4), user-operable means (15) for opening a door of the machine (1), and processor means (14) for controlling operation of said user-operable means (15) in accordance with an output from said water level sensing means (3, 4), characterised in that said processing means (14) is arranged to render said user-operable means (15) inoperable when the output indicates a relatively high water level, to initiate draining of the water from the machine (1), and to provide an indication to the user that said user-operable means (15) is operable when said output indicates that the machine (1) is substantially empty of water.

7. A washing machine as claimed in claim 6 wherein a further indication to the user is provided by the processor means (14) when the user-operable means (15) is rendered inoperable.

8. A washing machine as claimed in claim 6 or 7 wherein the first-mentioned indication comprises automatic opening of the door, provided by the processing means (14), when said output indicates that the machine (1) is substantially empty of water.

9. A washing machine as claimed in claim 7 or 8 wherein said further indication is audible to the user.

10. A washing machine as claimed in claim 7 or 8 wherein said further indication consists of illumination of a light emitting diode (17) provided on the machine (1).