Laundry appliance with capacitive laundry drying degree sensing function

Patent metadata

Field	Value
Publication number	US-11248334-B2
Application number	US-202016860488-A
Country	US
Kind code	B2
Filing date	Apr 28, 2020
Priority date	Oct 26, 2015
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

A method for measuring the humidity of a laundry mass contained in a laundry treatment chamber of a laundry appliance. The method includes: providing a capacitor in the laundry appliance, the capacitor having, as part of the capacitor dielectric, the laundry mass; measuring a capacitance of the capacitor by means of an electronic circuitry electrically supplied by a supply voltage and a reference voltage. Providing a capacitor comprises: providing in the laundry appliance at least one conductive plate which forms a plate of the capacitor, and exploiting, as a second plate of the capacitor, routing lines distributing inside the laundry drying appliance the reference voltage.

First claim

The invention claimed is:

1. A method for operating a laundry appliance having a laundry treatment chamber and a capacitor comprising at least one conductive plate which forms a first plate of the capacitor, a supply line configured to carry a supply voltage to a controller of the laundry appliance, routing lines configured to carry a reference voltage to the controller of the laundry appliance, the routing lines configured as a second plate of the capacitor, the controller connected to a supply voltage via a supply line and connected to the reference voltage via at least one of the routing lines, and a dielectric including a content of the laundry treatment chamber separating the first plate from the second plate, the method comprising:
generating the reference voltage on the routing lines and generating the supply voltage on the supply line;
measuring, by the controller, a capacitance between the at least one conductive plate and the routing lines of the capacitor; and
estimating, by the controller, a humidity of the content of the laundry treatment chamber based on the measured capacitance of the capacitor.

2. The method of claim 1 , wherein measuring a capacitance of the capacitor comprises:
coupling the capacitor to a feedback loop of a sigma-delta modulator comprising a reference capacitor;
switching the capacitor between a voltage source and a first node of the reference capacitor to provide a charge current to the reference capacitor using a plurality of switches, wherein a first of the plurality of switches is coupled between the voltage source and a first node of the capacitor and a second of the plurality of switches is coupled between the first node of the capacitor and the first node of the reference capacitor; and
converting the capacitance measured on a sensor element to a digital code proportional to the measured capacitance.

3. The method of claim 2 , further comprising:
alternately coupling the capacitor and a discharge circuit to the first node of the reference capacitor; and,
when the discharge circuit is coupled to the first node of the reference capacitor, discharging the reference capacitor.

4. The method of claim 3 , further comprising:
coupling the discharge circuit to the first node of the reference capacitor and discharging the reference capacitor when the voltage on the reference capacitor reaches a threshold reference voltage.

5. The method of claim 1 , wherein the content of the laundry treatment chamber comprises a laundry mass, and the method further comprising controlling a laundry mass drying operation of the laundry appliance based on the estimated humidity of the laundry mass.

6. The method of claim 5 , wherein controlling the laundry mass drying operation comprises one or more of:
controlling a power supplied to a drying air heating device for heating drying air which is caused to pass through the laundry treatment chamber;
controlling a drum rotational speed;
controlling a drum clockwise/counterclockwise rotation duty ratio;
controlling a drying process time duration; and
controlling a rotational speed of a drying air fan for propelling drying air.

7. The method of claim 5 , wherein controlling the laundry mass drying operation comprises:
determining control parameters; and
starting a drying process using the control parameters.

8. A laundry appliance comprising:
a laundry treatment chamber;
a controller connected to a supply line configured to carry a supply voltage to a controller and connected to at least one routing line of a plurality of routing lines configured to carry a reference voltage to the controller; and
a capacitor having:
a first plate comprising at least one conductive plate located inside the laundry appliance;
a second plate comprising the routing lines located inside the laundry appliance; and
a dielectric located between the first plate and the second plate and comprising a content of the laundry treatment chamber; and

wherein the controller is configured to determine a capacitance between the at least one conductive plate and the routing lines of the capacitor, and estimate a humidity of the contents of the laundry treatment chamber based on the capacitance of the capacitor.

9. The laundry appliance of claim 8 , wherein the controller is configured to control a drying operation of the laundry appliance responsive to the estimated humidity.

10. The laundry appliance of claim 9 , wherein the controller is configured to determine one or more drying process control parameters, the drying process control parameters including one or more of:
a power to be supplied to a drying air heating device;
a drum rotational speed and/or a drum clockwise/counterclockwise rotation duty ratio;
a drying process time duration; and
drying air fan rotational speed.

11. The laundry appliance of claim 8 , wherein the content of the laundry treatment chamber comprises a laundry mass, and the controller is configured to control a drying operation of the laundry drying appliance based on an estimated humidity of the laundry mass.

Assignees

• Electrolux Appliances AB

Inventors

• Vitali Fabio
• Romeo Vincenzo

Classifications

• D06F58/38 Primary

  of drying, e.g. to achieve the target humidity · CPC title

• D06F2103/10

  expressed as capacitance or resistance · CPC title

• D06F34/18

  Condition of the laundry, e.g. nature or weight · CPC title

• D06F2103/24

  Spin speed; Drum movements · CPC title

• D06F25/00

  Washing machines with receptacles, e.g. perforated, having a rotary movement, e.g. oscillatory movement, the receptacle serving both for washing and for centrifugally separating water from the laundry and having further drying means, e.g. using hot air  (control of washing or of washing and drying D06F33/00, D06F34/00; domestic laundry dryers D06F58/00) · CPC title