Laundry appliance and operating method

Patent metadata

Field	Value
Publication number	US-10907291-B2
Application number	US-201816163001-A
Country	US
Kind code	B2
Filing date	Oct 17, 2018
Priority date	Oct 17, 2017
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A method of operating a laundry washing (or washing and drying) machine, and a machine so operated, for determining whether an undetached laundry ring is present within the drum at the end of a washing cycle. The method includes rotating the drum at first and second rotational speeds, respectively below and above the threshold speed at which the load is centrifugally held against the drum's surface, measuring motor current/torque at each speed and comparing the measured values. Optionally, a percentage change in current/torque can be calculated and the existence of the ring detected if the percentage change is above/below a predetermined threshold value. Optionally, speed variation of the drum at each threshold speed can be determined and this information also used in the determination of whether the ring exists.

First claim

The invention claimed is:

1. A laundry washing or washing and drying machine comprising:
a cabinet,
a water container mounted within the cabinet,
a drum supported within the water container and rotatable relative thereto, the drum adapted to hold a laundry load,
an electric motor having a rotor connected for rotating the drum when energised to do so,
a current sensor to provide an indication of the motor current, and
a controller operable to energise the rotor to rotate the drum at selected rotational speeds and to receive the motor current indication from the current sensor, the controller configured to:
energise the motor to rotate the drum at a first rotational speed,
determine the magnitude of the motor current indication at the first rotational speed,
energise the motor to rotate the drum at a second rotational speed, different to the first rotational speed,
determine the magnitude of the motor current indication at the second rotational speed, and
decide whether undetached laundry is present on the drum by comparing the motor current magnitude indication at the first rotational speed to the motor current magnitude indication at the second rotational speed.

2. The laundry washing or washing and drying machine according to claim 1 , wherein the second rotational speed is greater than the first rotational speed, and wherein
the controller is further configured to decide that undetached laundry is not present on the drum if the motor current magnitude indication at the first rotational speed is greater than the motor current magnitude indication at the second rotational speed, or
the controller is further configured to decide that undetached laundry is present on the drum if the motor current magnitude indication at the first rotational speed is less than the motor current magnitude indication at the second rotational speed.

3. The laundry washing or washing and drying machine according to claim 1 , wherein the second rotational speed is greater than the first rotational speed, the controller further configured to:
calculate a value indicative of a percentage change in motor current magnitude between the first and second rotational speeds, and
decide that undetached laundry is not present on the drum if the calculated value indicates a percentage change in motor current magnitude from the first rotational speed to the second rotational speed which is greater than a predetermined percentage value, or
decide that undetached laundry is present on the drum if the calculated value indicates a percentage change in motor current magnitude from the first rotational speed to the second rotational speed which is less than a predetermined percentage value.

4. The laundry washing or washing and drying machine according to claim 1 , the controller further configured to energise the motor to rotate the drum at the first or second rotational speed for a predetermined period of time and the motor current magnitude indication for a particular rotational speed is determined by averaging a plurality of detected motor current magnitude indication values at that particular rotational speed during the predetermined period of time.

5. The laundry washing or washing and drying machine according to claim 1 , wherein the controller is configured to set the first rotational speed below the speed required to centrifugally hold the laundry load against the surface of the drum for a complete drum rotation and to set the second rotational speed sufficiently high to hold the laundry load against the surface of the drum for a complete drum rotation.

6. The laundry washing or washing and drying machine according to claim 1 , further comprising a speed detector for determining the rotational speed of the rotor or drum, wherein the controller is further configured to:
determine a first value indicative of the variation in speed of the motor or drum while the motor is energised to rotate the drum at a predetermined rotational speed,
determine a second value indicative of the variation in speed of the motor or drum while the motor is energised to rotate the drum at a further predetermined rotational speed, different to the predetermined rotational speed, and
decide whether undetached laundry is present on the drum by comparing the motor current magnitude indication at the first rotational speed to the motor current magnitude indication at the second rotational speed, and by comparing the first value to the second value.

7. The laundry washing or washing and drying machine according to claim 6 , wherein the further predetermined rotational speed is greater than the predetermined rotational speed, and the second rotational speed is greater than the first rotational speed, and wherein
the controller is further configured to decide that undetached laundry is not present on the drum if the motor current magnitude indication at the first rotational speed is less than the motor current magnitude indication at the second rotational speed, and the first value is less than the second value, or
the controller is further configured to decide that undetached laundry is present on the drum if the motor current magnitude indication at the first rotational speed is less than the motor current magnitude indication at the second rotational speed, and the first value is greater than the second value.

8. The laundry washing or washing and drying machine according to claim 6 , wherein the controller is further configured to energise the motor to rotate the drum at the predetermined rotational speed or the further predetermined rotational speed for a predetermined period of time and each value indicative of a variation in speed for a particular rotational speed is determined by averaging a plurality of detected speed variation values at that particular rotational speed during the predetermined period of time.

9. The laundry washing or washing and drying machine according to claim 6 , wherein the controller is further configured to set the first rotational speed equal to the predetermined rotational speed and to set the second rotational speed equal to the further predetermined rotational speed.

10. The laundry washing or washing and drying machine according to claim 2 , wherein the controller is configured to set the first rotational speed below the speed required to centrifugally hold the laundry load against the surface of the drum for a complete drum rotation and to set the second rotational speed sufficiently high to hold the laundry load against the surface of the drum for a complete drum rotation.

11. The laundry washing or washing and drying machine according to claim 3 , wherein the controller is configured to set the first rotational speed below the speed required to centrifugally hold the laundry load against the surface of the drum for a complete drum rotation and to set the second rotational speed sufficiently high to hold the laundry load against the surface of the drum for a complete drum rotation.

12. The laundry washing or washing and drying machine according to claim 4 , wherein the controller is configured to set the first rotational speed below the speed required to centrifugally hold the laundry load against the surface of the drum for a complete drum rotation and to set the second rotational speed sufficiently high to hold the laundry load against the surface of the drum for a complete drum rotation.

13. The laundry washing or washing and drying machine according to claim 2 , further comprising a speed detector for determining the rotational speed of the rotor or drum, wherein the controller is further configured to:
determine a first value indicative of the variation in spee

Assignees

• Fisher & Paykel Appliances Ltd

Inventors

• Chai Shan

Classifications

• D06F35/007

  for spin-drying only · CPC title

• D06F34/20

  Parameters relating to constructional components, e.g. door sensors · CPC title

• D06F33/48

  Preventing or reducing imbalance or noise · CPC title

• D06F2105/60

  Audible signals · CPC title

• D06F34/16 Primary

  Imbalance · CPC title