Processing

Please wait...

Settings

Settings

Goto Application

1. WO2009007380 - SYSTEM AND ELECTRONIC CIRCUIT USED TO PROTECT THE DOOR OF WASHING MACHINES OR WASHER-DRIERS

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

Description

SYSTEM AND ELECTRONIC CIRCUIT USED TO PROTECT THE DOOR OF WASHING MACHINES OR WASHER-DRIERS

The present patent application relates to a system and an electronic circuit to protect the door of washers or washer-driers, able to prevent the door from opening when the drum with laundry is still in rotation.
The system of the invention and relevant actuation circuit have been 5 expressly devised for installation with doors used to access the drum with the laundry equipped with a closing device with thermal actuator to activate the door lock mechanism after closing.
In order to understand the drawbacks remedied by the present invention, reference must be made to the configuration and operation of the io electrical system and electronic control unit used to programme, manage and check the ordinary safe operation of the said appliances.
For clarity purposes, this invention continues with reference to figure 1 that is a block diagram of the electrical power supply circuit of all actuators installed in an ordinary washer or washer-drier, in particular showing the

15 electrical motor and the door-lock device with the aforementioned thermal actuator.
With reference to the said figure, the door lock (1 ) is powered directly by a microcontroller (2) that also power the motor (3) and all the other actuators (4) of the appliance.
20 When you close the door and press the start button of the appliance, the microcontroller (2) instantaneously activates the power supply of the door lock (1 ), and the thermal actuator expands in a very few seconds generating two types of effect; the first effect is a merely mechanical effect and consists in the activation of the temporary lock mechanism of the door lock; the 25 second effect is of electrical type and consists in the switching off of a switch that give permission for the start of the electrical motor (3).
The presence of the said switch inside the door lock (1 ) directly actuated by the thermal actuator prevents the risk that the motor is started when the door is not closed, and the presence of the said thermal actuator prevents the door from being accidentally opened when the motor in is operation.
The latter protection feature remains in operation for a few tens of seconds after the interruption of the electrical power supply of the motor (3) by the door lock (1 ) that automatically interrupts the power supply of all actuators as son as the selected washing programme is completed.
In fact, the door cannot be opened before the time necessary to cool the thermal actuator down has passed, which typically takes almost one minute to minimise its extension.
In practical terms, the door can be opened approximately one minute after disconnecting the motor power supply.
The aforementioned safety system is not effective if a failure occurs upstream the door-lock (1 ) after the motor (3) is started, causing the interruption of power supply of the thermal actuator, such as the failure of the relevant PIN in the microcontroller (2) or the failure of the TRIAC that powers the said actuator and of the electrical heating downstream the TRIAC.
In such a case, the motor (3) would continue on rotating until the thermal actuator has cooled down completely, thus determining the deactivation of the stop mechanism of the door, which can be opened when the motor (3) is no longer powered.
This type of failure may cause a dangerous situation during the laundry spinning cycle, after which the drum continues to rotate for several seconds by inertia, although the motor is not longer powered.
In such a case, the cooling of the thermal actuator may be completed when the spinning cycle is still in progress, in such a way that the door can be opened when - in spite of the motor being not powered - the drum has just started or has not in any case completed the inertial deceleration phase.
The purpose of the present invention is to devise a system and a safety circuit that are effective also in the aforementioned case of failure.
To that end, the system of the invention provides for the actuation of an auxiliary electrical connection between the motor and the door lock in such a way that the thermal actuator of the door lock is powered when the motor is in operation, regardless of any failure that may occur upstream the door lock along the electrical connection line between the door lock and the microcontroller.
In this way, the cooling down of the thermal actuator cannot start while the electrical power is powered; this condition guarantees safety since the cooling time of the electrical actuator is certainly longer than the inertial deceleration phase of the drum after-spinning.
This and other characteristics of the system and safety circuit of the invention will become clear after the following description, which refers to the enclosed figures, which are intended for purposes of illustration only, and not in a limiting sense, wherein:
- fig. 2 is a block diagram that shows the position of the safety circuit of the invention in the electrical power supply circuit of all the actuators installed in an ordinary washer or washer-drier;
- fig. 3 is the electrical actuation diagram of the safety circuit of the invention.

With reference to fig. 2, the safety system of the invention provides for a safety circuit (5) positioned between the motor (3) and the door-lock (1 ) in such a way that the thermal actuator installed in the door-lock (1 ) is powered when the motor (3) is in operation.
The following numerals are used in the electrical diagram of fig. 3 to identify the following blocks:
- microcontroller: block (2)
- motor control circuit: block (6)
- door-lock safety circuit: block (5)
- power supply unit: block (7).
In the electrical diagram of fig. 3 the connection port of the door-lock (1 ) is marked with numeral (1 a), while the connection port of the motor (3) is marked with numeral (3a).
The safety circuit (5) comprise an electrical connection line (5a) between the control circuit (6) of the motor (3) and the door-lock (1 ) in order - A - to power the door-lock (1 ) when the motor (3) is in operation.
A pair of diodes (D2) and (D3) is provided along the connection line (5a) in parallel.
The presence of two diodes (D2 and D3) instead of only one diode is explained with the need to ensure the efficacy of the safety circuit (5) also in case of failure of one diode.
The presence of the safety circuit (5) of the invention provides for the introduction of a diode (D1 ) positioned between the circuit (5) and the triac (TR2) that powers the connection port (1 a) of the door-lock (1 ) in order to avoid the recirculation of negative current through the triac (TR2).
As mentioned above, the presence of the safety circuit (5) between the motor (3) and the door-lock (1 ) ensures powering the door-lock (1 ) through the motor control circuit (6) also in case of accidental failure of the triac (TR2) or heating element (R9) associated with the triac (TR2) situated along the electrical connection line between the microcontroller (2) and the door-lock

(1 )-