CROSS REFERENCE TO RELATED APPLICATION

This application is a US 371 application from PCT/EP2019/066003 entitled “Washing Machine and Method of Operation” filed on Jun. 18, 2019 and published as WO 2020/253945 A1 on Dec. 24, 2020. The technical disclosures of every application and publication listed in this paragraph are hereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a washing machine and a method of operating a washing machine.

BACKGROUND

Washing machines are used for washing laundry items, including for example clothing, bedding, towels, etc. Some washing machines also provide a tumble dryer function, and are often referred to as combined washing-drying machines or washer-dryers or the like. As used herein, the term “washing machine” shall be understood to include machines that only provide a washing function and combined washing-drying machines which provide a washing function and a tumble drying function, unless the context requires otherwise.

A washing machine typically has a spin cycle which takes place after the washing cycle. During a spin cycle, the drum of the washing machine is rotated at a relatively high rate of rotation to cause excess water in the laundry to be spun out (through “centrifugal” force). This reduces the water content of the laundry before the laundry is removed from the washing machine to be dried (in a separate tumble dryer or on a washing line or the like) or before a tumble dryer function is implemented to dry the laundry in the case of a combined washer-dryer.

SUMMARY

According to a first aspect disclosed herein, there is provided a washing machine, the washing machine comprising:

a rotatable drum for receiving items to be washed;

a tub in which the drum is mounted for rotation;

a motor for driving rotation of the drum in the tub;

at least a first water sensor and a second water sensor;

the first water sensor being located at or towards the bottom of the tub and arranged to measure the level of water collected at the bottom of the tub;

the second water sensor being located at a part of the tub away from the first water sensor and arranged to measure the amount of water being thrown out of the drum as the drum rotates; and

a controller for receiving outputs from the sensors and for controlling the motor to rotate the drum, wherein the controller is configured to control the motor to rotate the drum in accordance with a difference of the outputs of the sensors.

The use of (at least) two sensors enables a more accurate and more representative measurement of the amount of water remaining in the items in the drum to be obtained, in a way that is relatively simple and inexpensive to implement. The first waster sensor, located at or towards the bottom of the tub, effectively provides a baseline for the measurements by the second water sensor.

In an example, the controller is configured to control the motor to rotate the drum in accordance with a difference of the outputs of the sensors during a spin cycle such that the controller causes the spin cycle to cease when the magnitude of the difference of the outputs of the sensors exceeds a threshold.

In an example, the controller is configured such that the difference of the outputs of the sensors that is used by the controller to control the motor is an averaged difference.

This use of an averaged or “smoothed” difference helps to avoid “spikes” in the outputs of the sensors being acted upon incorrectly by the controller, given that spikes in the water that is collecting at the bottom of the tub and in the amount of water being thrown out of the drum as the drum rotates can occur in practice. The controller may carry out the averaging or smoothing.

In an example, at least one of the water sensors is a capacitive sensor.

In an example, each water sensor is a capacitive sensor.

According to a second aspect disclosed herein, there is provided a method of operating a washing machine having a rotatable drum containing items to be washed, the drum being mounted for rotation in a fixed tub of the washing machine, the method comprising:

rotating the drum;

measuring the level of water collected at the bottom of the tub;

measuring, at a part of the tub away from the bottom of the tub, the amount of water being thrown out of the drum as the drum rotates; and

controlling rotation of the drum in accordance with a difference of the measurements.

In an example, the rotation of the drum is controlled in accordance with a difference of the measurements during a spin cycle such that the spin cycle is ceased when the magnitude of the difference of the measurements exceeds a threshold.

In an example, the method comprises averaging the difference of the measurements and controlling rotation of the drum in accordance with the averaged difference of the measurements.

In an example, at least one of the water sensors is a capacitive sensor.

