GB2269395A

GB2269395A - Overload detection in a laundry treatment machine

Info

Publication number: GB2269395A
Application number: GB9315255A
Authority: GB
Inventors: Siegmar Schwarz
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-04
Filing date: 1993-07-23
Publication date: 1994-02-09
Anticipated expiration: 2013-07-23
Also published as: GB9315255D0; DE4225769A1; DE4225769C2; SE9302493D0; NL9301023A; SE509056C2; NL194336B; GB2269395B; SE9302493L; NL194336C

Abstract

An automatic laundry treatment machine comprises a laundry drum (1) with loading opening (6) and with a detector (8) for detecting the weight of the laden drum. The detector is connected to an evaluating circuit which, on detection of a weight that is unacceptably high for the operational state of the machine, delivers a blocking signal to prevent the start of a program of the machine. <IMAGE>

Description

2269395 OVERLOAD DETECTION IN A LAUNDRY TREATMENT MACHINE The present

invention relates to an automatic laundry treatment machine, especially a household machine with measures for-,the detection of the weight of a drum of the machine.

A laundry treatment machine with such a measure is known from German published specification 30 25 088. By means of fully automatic detection and evaluation of the increase in weight caused by laundry in the drum it is able to precisely match important parameters of the subsequent laundry treatment process to the laundry load that is present. The aim of such measures is an as complete as possible detection of weight and consideration of all parameters required for the laundry treatment process so that the treatment process after the loading in of - the laundry and the starting of the machine can be matched fully automatically to the load.

This very worthwhile objective, however, tonceals dangers which result from the operator no longer having to exert any particular mental effort for the operation of the machine. Consequently, children are in a position to set such a machine into action. This could lead to children starting the machine after one has climbed into. the laundry drum.

It would thus be desirable to provide a measure by which the laundry treatment process cannot be set into operation when a child with a weight of, for example, more than 5 kilograms is in the drum.

According to the present invention there is provided an automatic laundry. _ treatment machine comprising a laundry drum with a loading opening, detecting means to detect the weight of the loaded drum, and evaluating means to evaluate the value of the detected weight and to issue a signal for blocking start of a program or part of a program of the machine if the detected weight value exceeds a laden weight value predetermined to be excessive for the operational state of the machine.

The threshold value for the weight at which the blocking signal shall be delivered can be fixed or variable.

Preferably, the evaluating means comprises comparison means and storage means for several threshold values of load weights, which values can be individually called up according to the state of the program and fed, together with the actual detected value of the load weight, to the comparison means. For example, the probable loaded weight for a washing machine before the start of the laundry treatment process may be equal to or smaller than 4.5 kilograms. The threshold value could thus be adjusted to 4.5 kilograms. Through this measure, the advantage results that a washing program cannot be started when the drum is overloaded. In this connection, an optical or other signal at an operating panel of the machine can also be helpful.

In further program sections, the laden weight of the drum may be appreciably higher due to the take-up of water by the laundry, so that it may be of advantage to adjust the threshold value to be correspondingly higher for those sections. This can also be of significance in a combined washing and drying machine in which, for example, a laundry loading of only 3.5 kilograms of dry laundry is permissible for the drying program following on the washing program.

In a drying machine, the threshold value can be set to, for example, 8 kilograms according to a loading weight of 4.5 kilograms of dry laundry plus the moisture taken up in the laundry after a spinning run following a preceding washing and spinning program. The threshold value can be selected so that a laundry charge with too great a component of water cannot be dried automatically in order that there is not undue wastage of thermal energy. Such a laundry charge should first be spun dry to such an extent that only a minimum amount of thermal energy is required for the expulsion of the residual moisture.

Thus, a dripping wet laundry charge can be excluded from drying in the machine.

An embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic vertical sectional view of part of a drier embodying the invention, along the centre line of a drum of the drier; and Fig. 2 is a block circuit diagram of detecting,evaluating and control means of the drier.

Referring now to the drawings there is shown in Fig. 1 part of a laundry drier comprising a laundry drum 1 which carries at its rear wall 2, which is perforated in the middle region, a bearing shaft 3 rotatably mounted in a drum bearing 4. In addition, in the region of a loading opening 6, the drum has a flange 27 for a further bearing, a front drum bearing 7. The bearing 7 comprises a seal 9, which is fastened on a frame part 12 around the opening 6 and in which slide members are embedded. The seal 9 can comprise felt strips and prevents the compressed air fed into the drum interior from escaping through bearing gaps. Instead, the air passes through a perforated laundry deflector 10 in the loading door and into a channel (not illustrated) which leads the air back to the drum interior after renewed heating by way of a heater 11. Rear sealing rings 13 of a similar kind seal off the drum 1 against the outside at the air protection channel 14.

A measurement pick-up 8, which,r4cts to pressure or movement and which in response to pressure or movement by articles placed in the drum 1 delivers a signal, is arranged at the front drum bearing 7. When the drum i s loaded, the drum axis lowers by a minimum angular amount.

In place of a weight-detecting pick-up 8 arranged in the front bearing 7, a weight pick-up, which, for example, signals stress arising in the bearing 4 or at the rear wall 15 of the drum, can be arranged at the rear bearing 4. In addition, the bearing can be arranged between springs to be vertically movable and the deflection of the bearing can represent a measure of the load weight of the drum.

Fig. 2 shows, in the form of a schematic block diagram, a circuit by which signals indicative of the load weight of the drum can be processed. The pick-up 8 delivers weight signals to a comparator 16, which compares these signals with a threshold value signal delivered by a threshold value signal..generator 17. As soon as the weight signals from the pick-up 8 indicate a greater quantity of loading than that determined by the threshold value signal, a negative output signal of the comparator 16 changes into a positive output signal. This positive signal is applied to the inverting input of a coincidence stage 18, which issues at its output a blocking signal which is applied to a program control device 19. Normally, i.e. in the case of normal loading of the drum 1, the output line of the comparator 16 carries a negative potential which is converted by the inversion at the stage 18 into a positive potential. When, on actuation of a start button 20 of the laundry drier, a positive potential is applied to the other input of the stage 18, the output of the stage 18 then carries a start signal for the program control device 19. It is ensured that the drier cannot be put into operation when the loading of the drum has a weight exceeding the normal amount.

The threshold value signal generator 17 can include a storage device for several different threshold values, which can be read out by a signal of the device 19 in dependence on the state of the program. In that case different threshold values for the load can be preset for the comparator 16 so that different maximum load values for different states of the program can be taken into consideration.

1

Claims

1 An automatic laundry treatment machine comprising a laundry drum with a loading opening, detecting means to detect the weight of the loaded drum, and evaluating means to evaluate the value of the detected weight and to issue a signal for blocking start of a program or part of a program of the machine if the detected weight value exceeds a laden weight value predetermined to be excessive for the operational state of the machine.

2. A machine as claimed in claim 1, the evaluating means comprising means for storing a plurality of such predetermined laden weight values each associated with a respective section of the program, means for reading out the stored weight values in dependence on the program phase, and means for comparing read-out weight values with detected weight values.

3. A machine as claimed in claim 1 or claim 2, comprising indicating means responsive to the signal to provide an opticalindication.

4. A machine as claimed in any one of the preceding claims, the machine being a household laundry washing or drying machine.

5. A machine substantially as hereinbefore described with reference to the accompanying drawings.