GB2275992A - Controlling tumble dryers - Google Patents

Controlling tumble dryers Download PDF

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Publication number
GB2275992A
GB2275992A GB9304652A GB9304652A GB2275992A GB 2275992 A GB2275992 A GB 2275992A GB 9304652 A GB9304652 A GB 9304652A GB 9304652 A GB9304652 A GB 9304652A GB 2275992 A GB2275992 A GB 2275992A
Authority
GB
United Kingdom
Prior art keywords
relative humidity
process according
change
rate
drying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9304652A
Other versions
GB9304652D0 (en
GB2275992B (en
Inventor
Jane Anita Price
Geoffrey John Williams
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alstom Power UK Holdings Ltd
Original Assignee
Alstom Power UK Holdings Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alstom Power UK Holdings Ltd filed Critical Alstom Power UK Holdings Ltd
Priority to GB9304652A priority Critical patent/GB2275992B/en
Publication of GB9304652D0 publication Critical patent/GB9304652D0/en
Publication of GB2275992A publication Critical patent/GB2275992A/en
Application granted granted Critical
Publication of GB2275992B publication Critical patent/GB2275992B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F58/00—Domestic laundry dryers
    • D06F58/32—Control of operations performed in domestic laundry dryers 
    • D06F58/34—Control of operations performed in domestic laundry dryers  characterised by the purpose or target of the control
    • D06F58/36—Control of operational steps, e.g. for optimisation or improvement of operational steps depending on the condition of the laundry
    • D06F58/38—Control of operational steps, e.g. for optimisation or improvement of operational steps depending on the condition of the laundry of drying, e.g. to achieve the target humidity
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
    • D06F2103/02—Characteristics of laundry or load
    • D06F2103/08—Humidity
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
    • D06F2103/28—Air properties
    • D06F2103/34—Humidity
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
    • D06F2105/28—Electric heating
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
    • D06F2105/62—Stopping or disabling machine operation

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Control Of Washing Machine And Dryer (AREA)

Abstract

A drying process for use particularly in commercial laundry batch tumble driers. Exhaust air is sampled isokinetically and its relative humidity measured. The machine is then switched off, to terminate the drying process, when the rate of change of relative humidity falls to a predetermined reference value. By operating in dependence on the rate of change of humidity, errors due to inaccuracy and drift in measurements are avoided.

Description

Process and Apparatus for Drying Articles or Material This invention relates to a drying process and apparatus for performing a drying process.
Drying equipment, for example in laundries, comnonly uses heated air and tumbling of the article or material. Relatively dry air is blown in and moist air is exhausted. By measuring the relative humidity of the exhaust air an indication can be obtained of the dryness of the article/material and the equipment switched off accordingly. However, a problem arises in the operation of comnercial laundry batch tumble dryers in that the humidity measuring apparatus is subject to inaccuracy and drift problems.
An object of the invention is therefore to provide a drying process which is not subject to the above accuracy and drift problems or at least not to the same extent as known processes.
According to the present invention, in a drying process in which the article or material to be dried is subjected to heat and the passage of air, the exhaust air being sampled and the relative humidity of the sample measured, the rate of change of relative humidity is determined and the drying process modified in dependence upon the rate of change so determined.
The modification may consist in partially or completely reducing the supply of heat to the article or material being dried, and may entail switching off the drying equipment.
The modification may be effected when the determined rate of change of relative humidity reaches a predetermined value or has followed a predetermined series of values over a predetermined time.
The exhaust air is preferably sampled isokinetically.
According to another aspect the invention consists in drying equipment operable in accordance with a process as aforesaid.
A drying process in accordance with the invention will now be described by way of example.
The process is used to control a laundry batch tumble drier in which in known manner damp laundry articles are placed in a rotatable drum through which warm air is circulated typically by an electric fan. As the clothes are tumbled moisture is taken up by the warm air and the moisture-laden air exhausted through an exhaust duct.
An isokinetic sampling rake is fitted to the exhaust duct to divert a small sample of exhaust air to a sampling chamber. The isokinetic sampling ensures no disturbance to the exhaust air sample in the sampling process thus ensuring that the sample is not subject to any temperature change such as to affect its relative humidity.
The relative humidity of the sample is measured in the sampling chamber on a continuous basis throughout the drying process by known measuring apparatus. The measured value is then sampled at intervals of, say, 20 seconds, digitally coded and stored. The stored values are subtracted, each from the last, and the difference compared against a predetermined reference value. As the drying process progresses, this difference will decrease until it is exceeded by the reference value. At this point a control signal is produced to switch off the drier.
In a modification of this process, the difference values referred to above are compared by a curve-fitting process to a succession of predetermined difference values. The control (switch-off) signal is then produced only when the measured curve of relative humidity against time coincides, over a number of intervals, and within predetermined limits, with the reference curve.
In a further modification the control signal may modify the operation in a manner other than simply to switch it off. For example, the heating alone might be switched off, leaving the airflow to continue for some fixed time; again, the heating might be reduced to a lower value. In any event the control signal modifies the operation to a greater or lesser extent.
Another aspect of the invention consists in equipment adapted to operate the inventive process.
While the invention is particularly suitable for use in the drying of clothing etc in a laundry, it will also find application in drying processes generally - for particulate/granular material for example, whether in batch or continuous form.

Claims (8)

1. A drying process in which the article or material to be dried is subjected to heat and the passage of air, wherein the exhaust air is sampled and the relative humidity of the sample measured, the rate of change of relative humidity is determined and the drying process modified in dependence upon the rate of change so determined.
2. A process according to Claim 1, wherein the modification comprises reducing the supply of heat to the article or material being dried.
3. A process according to Claim 2, wherein the modification comprises reducing to zero the supply of heat to the article or material being dried.
4. A process according to Claim 1, wherein the modification comprises switching off the drying equipment.
5. A process according to any preceding claim, wherein the modification is effected when the determined rate of change of relative humidity reaches a predetermined value.
6. A process according to any of Claims 1-4, wherein the modification is effected when the measured relative humidity has followed a predetermined series of values over a predetermined time.
7. A process according to any preceding claim, wherein the exhaust air is sampled isokinetically.
8. Drying equipment operable in accordance with a process according to any preceding claim.
GB9304652A 1993-03-08 1993-03-08 Process and apparatus for drying articles or materials Expired - Fee Related GB2275992B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9304652A GB2275992B (en) 1993-03-08 1993-03-08 Process and apparatus for drying articles or materials

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9304652A GB2275992B (en) 1993-03-08 1993-03-08 Process and apparatus for drying articles or materials

Publications (3)

Publication Number Publication Date
GB9304652D0 GB9304652D0 (en) 1993-04-28
GB2275992A true GB2275992A (en) 1994-09-14
GB2275992B GB2275992B (en) 1997-01-08

Family

ID=10731635

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9304652A Expired - Fee Related GB2275992B (en) 1993-03-08 1993-03-08 Process and apparatus for drying articles or materials

Country Status (1)

Country Link
GB (1) GB2275992B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2772898A1 (en) * 1997-12-19 1999-06-25 Esswein Sa METHOD FOR DETERMINING THE DEVELOPMENT OF DRYING IN A DRYING PROCESS, AND IMPLEMENTING MACHINE
WO2011074840A2 (en) * 2009-12-15 2011-06-23 엘지전자 주식회사 Method for controlling a laundry treatment apparatus
CN114606745A (en) * 2022-03-09 2022-06-10 创维电器股份有限公司 Trunk judging method of clothes dryer

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4356641A (en) * 1980-12-15 1982-11-02 Armstrong World Industries Kiln control system
US4580354A (en) * 1983-05-18 1986-04-08 Stora Kopparbergs Bergslags Ab Method and device for measuring humidity
US4644665A (en) * 1982-11-10 1987-02-24 Firma Glatt Gmbh Process for supervising and/or controlling of physical treatment processes and bioreactions in ventilation systems as well as device for executing the process
US4704805A (en) * 1986-10-20 1987-11-10 The Babcock & Wilcox Company Supervisory control system for continuous drying
US4795871A (en) * 1986-10-20 1989-01-03 Micro Dry, Inc. Method and apparatus for heating and drying fabrics in a drying chamber having dryness sensing devices
EP0428846A1 (en) * 1989-09-22 1991-05-29 Asko Cylinda Ab Tumble drier

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4356641A (en) * 1980-12-15 1982-11-02 Armstrong World Industries Kiln control system
US4644665A (en) * 1982-11-10 1987-02-24 Firma Glatt Gmbh Process for supervising and/or controlling of physical treatment processes and bioreactions in ventilation systems as well as device for executing the process
US4580354A (en) * 1983-05-18 1986-04-08 Stora Kopparbergs Bergslags Ab Method and device for measuring humidity
US4704805A (en) * 1986-10-20 1987-11-10 The Babcock & Wilcox Company Supervisory control system for continuous drying
US4795871A (en) * 1986-10-20 1989-01-03 Micro Dry, Inc. Method and apparatus for heating and drying fabrics in a drying chamber having dryness sensing devices
EP0428846A1 (en) * 1989-09-22 1991-05-29 Asko Cylinda Ab Tumble drier

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2772898A1 (en) * 1997-12-19 1999-06-25 Esswein Sa METHOD FOR DETERMINING THE DEVELOPMENT OF DRYING IN A DRYING PROCESS, AND IMPLEMENTING MACHINE
EP0926292A1 (en) * 1997-12-19 1999-06-30 Esswein S.A. Method for determining the drying progression in a drying phase and machine using such method
WO2011074840A2 (en) * 2009-12-15 2011-06-23 엘지전자 주식회사 Method for controlling a laundry treatment apparatus
WO2011074840A3 (en) * 2009-12-15 2011-12-22 엘지전자 주식회사 Method for controlling a laundry treatment apparatus according to target relative humidity
CN102656315A (en) * 2009-12-15 2012-09-05 Lg电子株式会社 Method for controlling a laundry treatment apparatus according to target relative humidity
US8966785B2 (en) 2009-12-15 2015-03-03 Lg Electronics Inc. Method for controlling a laundry treatment apparatus according to target relative humidity
CN102656315B (en) * 2009-12-15 2015-08-19 Lg电子株式会社 For controlling the method for clothes treatment device according to target relative humidity
CN114606745A (en) * 2022-03-09 2022-06-10 创维电器股份有限公司 Trunk judging method of clothes dryer

Also Published As

Publication number Publication date
GB9304652D0 (en) 1993-04-28
GB2275992B (en) 1997-01-08

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PCNP Patent ceased through non-payment of renewal fee