GB2288456A

GB2288456A - Method of controlling the thermal energy consuption of a washer-drier

Info

Publication number: GB2288456A
Application number: GB9505633A
Authority: GB
Inventors: Peter Zinkann; Wolfhard Jording; Gerhard Rodefeld
Original assignee: Miele und Cie KG
Current assignee: Miele und Cie KG
Priority date: 1994-03-26
Filing date: 1995-03-21
Publication date: 1995-10-18
Anticipated expiration: 2015-03-21
Also published as: FR2717832B1; ITMI950552A0; DE19504249C2; DE19504249A1; IT1275943B1; FR2717832A1; GB2288456B; ITMI950552A1; GB9505633D0

Abstract

The invention relates to a method of controlling the thermal energy consumption of a washer-drier, more especially a waste air drier, having a drying chamber with an air inlet and an air outlet, a heating means disposed in front of the air inlet and a program control means mu c for actuating the heating means which comprises two heating resistors R1, R2 connected to the mains voltage supply of the drier via switches of two relays S1, S2. With washer-driers, it is known to control the thermal energy in dependence on a temperature value measured during the drying process. In order to reduce the consumption of electrical energy of a drier, more especially a waste air drier, by intensive utilisation of the environmental (solar) energy on warm days, an ambient air temperature value TR is measured via at least one temperature sensor (via signal input 4) prior to the heating device being set in operation, and the heating means is actuated by the program control means mu c in dependence on the ambient air temperature value TR. <IMAGE>

Description

METHOD OF CONTROLLING THE THERMAL ENERGY CONSUMPTION OP A WA8HER-DRIER The invention relates to a method of controlling the thermal energy of a washer-drier, more especially a waste air drier, having a drying chamber with an air inlet and an air outlet, a heating means disposed in front of the air inlet and a program control means for actuating the heating means.

With washer-driers, it is known (DE 33 36 633 Al) to control the thermal energy in dependence on a temperature value measured during the drying process.

Such an arrangement permits the thermal energy to be adapted to the air temperature, which increases when the residual moisture content drops. With such a method, however, it is not possible to react to the temperature conditions prevailing in the surrounding region of the drier.

It is also known (DE 30 30 864 Al) to measure the surrounding temperature of the drier prior to the commencement of a program for a drying process.

However, this is only effected so as to form a differential value between the surrounding temperature and the internal temperature of the drier, in order to shorten the drying process if there is any heat remaining from an earlier drying program. There is also no direct reaction here to changed surrounding temperature conditions.

The present invention seeks to solve the problem of reducing the consumption of electrical energy of a drier, more especially a waste air drier, by intensive utilisation of the environmental (solar) energy on warm days.

According to the present invention there is provided a method of controlling the thermal energy consumption of a washer-drier, more especially a waste air drier, having a drying chamber with an air inlet and an air outlet, a heating means disposed in front of the air inlet and a program control means for actuating the heating means, wherein an ambient air temperature value TR is measured via at least one temperature sensor prior to the heating means being set in operation, and wherein the heating means is actuated by the program control means in dependence on the ambient air temperature value TR. Advantageous embodiments are found in the following sub-claims.

The advantages which can be achieved with the arrangement according to the invention reside in the fact that, when there is a high ambient air temperature in the surrounding region, a reduction in the thermal energy and, in consequence, a saving of energy are possible.

One embodiment of the invention is illustrated purely schematically in the drawing and explained more fully hereinafter: The Figure is a block circuit diagram of the heating means for a condensing washer-drier configured in accordance with the invention and illustrates the actuation of said heating means by the program control means (pC). The heating means comprises two heating resistors (R1, R2), which are connected to the mains voltage supply of the drier via the switches of two relays (S1, S2)'.

These relays (S1, S2)' are actuated via two control lines (1, 2), which are switchable by the program control means (C). The program control means (?c) additionally has a first signal input (3), via which said control means receives a voltage signal Xw, dependent on the moisture content in the washing, from a device for measuring the residual moisture content in the washing, such measuring device not being illustrated in the drawing. The program control means (yC) receives a temperature-dependent voltage signal T from a temperature sensor, which is likewise not illustrated in the drawing, via a second signal input (4). A NTC resistor (R1, R2) is preferably used as the temperature sensor. Said resistor is disposed in the process air duct of the drier in front of the drum and serves to measure the temperature of the drying air during the drying process. The washing can hereby be protected from overheating in known manner. Furthermore, a time measuring arrangement is incorporated in the program control means (pC).

At the beginning of the drying process, only the process air fan is set in operation prior to the heating means being switched-on, and ambient air is thus drawn-in by suction from the surrounding area of the drier. The first measured temperature values then correspond to the ambient air temperature value TR. In this manner two variable parameters for controlling the heating means can advantageously be measured with the same temperature sensor.

The determined ambient air temperature value TR is processed by the program control means (pC) and used as the control criterion for the switching of the two heating resistors (R1, R2). One example of the operating sequence for a drying program is described hereinafter: After the ambient air temperature TR has been measured, both heating resistors (R1, R2) are switchedon. This program step, with maximum thermal energy, continues in a purely time-controlled manner until a first switching time ti is reached. A rapid heating-up of the drying air is hereby achieved, and the program duration is thus shortened.

In a simple embodiment of the waste air drier according to the invention, the thermal energy is reduced if there is a minimum ambient air temperature value TR1 once the first switching time t1 has been reached. Such reduction may be effected by setting one or both of the heating resistors (R1, R2) or by switching-off one or both of the heating resistors (R1, R2).

In an alternative embodiment of the invention, a second control criterion, namely the moisture content Xw in the washing, is used to actuate the heating means in addition to the ambient air temperature value. This actuation is effected in such a manner that the thermal energy is reduced once a prescribed changeover moisture value Xwl has been reached, on condition that there is a minimum ambient air temperature value TRi.

In a second embodiment of the waste air drier according to the invention, the heating means can be actuated in such a manner that a plurality of changeover moisture values Xwi are inputted in a memory of the program control means (C) and recalled in dependence on the measured ambient air temperature value T, the thermal energy being reduced when the respectively recalled changeover moisture value Xwi is reached. In this case, rising changeover moisture values Xwi are advantageously recalled when the ambient air temperature rises, since an earlier changeover process and a greater saving of energy are thereby effected at a relatively high ambient air temperature TR.

R If the drying program has still not terminated when a second switching time t2 is reached, the full thermal energy is switched-on, i.e. the reduction is cancelled. Such an arrangement ensures that the drying program terminates within a prescribable time limit.

The above-mentioned method of actuating the thermal energy may automatically be effected in a waste air drier. In this case, it is advantageous to provide the user with the possibility of selecting a standard drying program by means of a cancellation button.

Another possibility is for methods to be started by the user, only if desired, by a so-called economy button.

Claims

1. A method of controlling the thermal energy consumption of a washer-drier, more especially a waste air drier, having a drying chamber with an air inlet and an air outlet, a heating means disposed in front of the air inlet and a program control means for actuating the heating means, wherein an ambient air temperature value TR is measured via at least one temperature sensor prior to the heating means being set in operation, and wherein the heating means is actuated by the program control means in dependence on the ambient air temperature value TR.

2. A method as claimed in claim 1, wherein a temperature-dependent resistor, preferably a NTC resistor, which is disposed in the process air duct of the drier, is used as the temperature sensor for measuring the ambient air temperature value TR, and wherein the ambient air temperature TR is measured when the process air fan is switched-on.

3. A method as claimed in claim 1 or 2, wherein the heating means comprises at least two heating resistors and wherein the thermal energy can be changed by permanently and/or cyclically switching -on or -off at least one heating resistor via relays, which are switched by the program control means.

4. A method as claimed in any of claims 1 to 3, wherein the thermal energy is reduced in dependence on the measured ambient air temperature value TR when a changeover moisture value Xwi is reached, said changeover moisture value being measured with a device for measuring the residual moisture content Xw in the washing.

5. A method as claimed in claim 4, wherein the changeover moisture value Xwi, at which the thermal energy is reduced, increases with a rising ambient air temperature value TR.

6. A method as claimed in any of claims 1 to 5, wherein the thermal energy is switched-off when an ambient air temperature limit value TR1 is measured.

7. A method as claimed in any of claims 1 to 6, wherein the maximum thermal energy is switched-on until a first switching time tl is reached, such time being measured with a time measuring arrangement.

8. A method as claimed in any of claims 4 to 7, wherein the reduction of the thermal energy is cancelled if a second switching time t2 is exceeded, such time being measured with a time measuring arrangement.

9. A method as claimed in any of claims 1 to 8, wherein the change in the thermal energy can be introduced or cancelled by a manually operable switch.

10. A method of controlling the thermal energy consumption of a washer drier, more especially a waste air drier, substantially as hereinbefore described with reference to the accompanying drawing.