EP3488042B1 - Door monitoring circuit for a domestic appliance - Google Patents

Description

The invention relates to a door monitoring circuit for a household appliance with a transmitter input and a status transmitter which is connected to the transmitter input and represents the state of a loading door of the household appliance. The invention also relates to a household appliance with such a door monitoring circuit and a microprocessor.

To avoid risks, for household appliances with a loading door that allows access to moving parts, precautions must be taken to prevent units from being switched on, which could potentially cause damage. In washing machines and dryers, for example, this includes the drive motor for the drum, but also pumps, heating and others.

A known possibility of such precautions is to lead the operating voltage of these units via a door switch, which interrupts the power supply to the units mentioned when the door is open. The switch must accordingly be able to switch the corresponding load. In addition, in this case the necessary supply voltage may have to be routed over relatively long and sufficiently dimensioned lines.

Such a door monitoring circuit is for example in the EP 2 290 147 A1 disclosed.

The use of microprocessors to control household appliances offers the possibility of implementing extensive security functions. However, such circuits are intrinsically safe, i.e. It must be ensured that basic safety functions are available even if the microprocessor malfunctions.

The invention creates a solution with which the risks mentioned can be avoided reliably but inexpensively.

This is achieved by a door monitoring circuit for a household appliance with the features of claim 1 and a household appliance with such a door monitoring circuit.

Accordingly, in a door monitoring circuit for a household appliance, a transmitter input, a status transmitter that is connected to the transmitter input and the State of a loading door of the household appliance, a HV relay input for controlling the door monitoring circuit with an HV relay control signal, a relay control output for controlling a network switching relay of the household appliance, and a monitoring unit that is connected to the relay control output, the Encoder input, the HV relay input and the door monitoring output is connected, the pole of the encoder input forming an input node which is connected to the monitoring unit and the monitoring unit is set up to provide the relay control output as a function of the HV relay control signal only to be controlled when the status transmitter indicates that the loading door of the household appliance is closed.

This means that the mains switching relay, which switches on the energy supply for critical loads such as heating, drive, fan, etc., can only be switched when the loading door is closed, regardless of whether the HV relay input is activated by a control of the household appliance . The direct hardware link between the status transmitter and the mains switching relay via the monitoring unit ensures intrinsically safe operation regardless of the function of the home appliance control.

According to a further advantageous embodiment of the invention, the status transmitter is connected between a supply voltage and ground via a pull-up resistor and a pull-down resistor. The status transmitter is thus integrated into a voltage divider, on the basis of which not only the status of the status transmitter, which represents the states of the loading door, can be determined, but also errors in the status sensor and its supply lines, e.g. Have a short circuit or interruption detected.

According to a further advantageous embodiment of the invention, the door monitoring circuit is equipped with a trigger input for controlling the door monitoring circuit by a microprocessor with a trigger signal which can change the state of the input node. This can be used to check whether the status sensor or the door monitoring circuit has hardware errors.

According to a further advantageous embodiment of the invention, a door signal output is provided which provides a signal depending on the state of the input node. The door monitoring circuit thus offers a switching point at which the state of the loading door can be queried by the control of the household appliance or by other units.

According to another aspect, the invention creates a household appliance with a door monitoring circuit and a microprocessor for controlling the HV relay input and for monitoring the door monitoring output.

According to a further advantageous embodiment of the invention, the microprocessor of the household appliance is also provided for controlling the trigger input.

Fig. 1.

ein schematisches Blockschaltbild einer Türüberwachungsschaltung gemäß einer ersten Ausführungsform der Erfindung,

Fig. 2.

ein schematisches Ablaufdiagramm für das erfindungsgemäße Verfahren; und

Fig. 3.

ein schematisches Ablaufdiagram für ein Verfahren gemäß einer Weiterbildung der Erfindung.

Further advantages and features of the invention emerge from the following description with reference to the accompanying drawings. In the drawings shows:

Fig. 1.

a schematic block diagram of a door monitoring circuit according to a first embodiment of the invention,

Fig. 2.

a schematic flow diagram for the method according to the invention; and

Fig. 3.

a schematic flow diagram for a method according to a development of the invention.

In Fig. 1 a first embodiment of a door monitoring circuit 10 according to the invention for a household appliance is shown schematically. The door monitoring circuit has a transmitter input 12, a trigger input 14 and an HV relay input 16. The door monitoring circuit also has a door signal output 20 and a door monitoring output 22.

A status transmitter 30 is connected to the transmitter input 12. The state transmitter 30 can be designed in different ways; for example as a simple door switch in the form of a closing contact 30a (in Figure 1 in solid lines) or as a Hall sensor 30b (in Figure 1 alternatively shown in dotted lines). The state transmitter 30 indicates the state of a loading door of the household appliance, that is, whether the door is open or closed. In the embodiment shown, the closing contact 30a of the status transmitter is closed when the loading door of the household appliance is closed.

The door monitoring circuit 10 also has a trigger processing unit 40 with a trigger input 42 and a trigger output 44, a monitoring unit 50 with a relay control input 52, a monitoring input 54, a relay control output 56 and a relay status output 58, and a door signal processing unit 60 with a door signal input 62 and a door signal output 54 on.

The status transmitter 30 is connected between a first pole 12a and a second pole 12b of the transmitter input 12. The first pole 12a is connected to a supply or reference voltage V _{SS of} the door monitoring circuit 10 via a pull-up resistor 32. The second pole 12b is connected to an input node 36 which is connected to the ground GND of the door monitoring circuit 10 via a pull-down resistor 34.

The trigger input 42 of the trigger processing unit 40 forms the trigger input 14 of the door monitoring circuit 10. The trigger output 44 of the trigger processing unit 40 is connected to the input node 36.

The door signal input 62 of the door signal processing unit 60 is also connected to the input node 36, and the door signal output 64 of the door signal processing unit 60 forms the door signal output 20 of the door monitoring circuit 10.

Finally, the monitoring input 54 of the monitoring unit 50 is also connected to the input node 36. The relay control input 52 of the monitoring unit 50 forms the HV relay input 16 of the door monitoring circuit 10 and the relay status output 58 of the monitoring unit 50 forms the door monitoring output 22 of the door monitoring circuit 10. The relay control output 56 of the monitoring unit 50 controls a network switching relay 70. The mains switching relay 70 is connected to a phase P of a mains supply voltage in order to switch a switched mains supply voltage P1 for consumers with mains voltage requirements in the household appliance, e.g. Switch the heating, drive motor etc. on and off.

The core of the door monitoring circuit 10 is the input node 36 and its electrical level. This level and its dependency on the state of the loading door of the household appliance should initially be considered without taking into account the function of the trigger processing unit 40.

If the closing contact 30a of the status transmitter is open, which corresponds to an open loading door in the embodiment shown, the level of the input node 36 is approximately at ground potential GND because of the connection via the pull-down resistor 34. In the same way, the state of the input node 36 would be coupled to the state of the loading door if a Hall sensor 30b was used as an alternative.

When the loading door is closed, however, the closing contact 30a of the status transmitter is closed. As a result, the level at the input node 36 is pulled up to the value of the supply voltage V _SS via the pull-down resistor 34, the actual level being essentially dependent on the ratio of the resistance values of the pull-up resistor 32 and the pull-down resistor 34 that form a voltage divider.

The level at the input node 36 also depends on the status of a trigger signal MAIN_TRIGGER at the trigger input 14 when the household appliance is in operation. In the simplest case, the trigger signal is provided by the microprocessor 80 at the trigger input 14. The trigger signal is preferably processed in the trigger processing unit 40, for example in the form of a level adjustment, an inversion, a D / A conversion or a combination thereof. The trigger processing unit 40 can also be designed to generate the trigger signal itself, controlled by a digital or analog control signal at the trigger input 14.

In the embodiment shown, the trigger input 14 is activated with the clock rate of the main routine of the microprocessor 80 and can assume the status MAIN_TRIGGER_ON or MAIN_TRIGGER_OFF . The electrical level of the input node 36 can thus be influenced via the trigger input 14 in such a way that the level depends both on the status of the trigger signal MAIN_TRIGGER and on the status of the status transmitter 30 and thus, in the embodiment shown, the status of the loading door.

The state of the input node 36 is queried by the microprocessor 80 at the door signal output 20. The signal at the door signal output 20 is processed by the door signal processing unit 60 so that it can be evaluated by an analog input of the microprocessor 80. The preparation can alternatively also for a different way a detection or control device connected to the door signal output 20, and contain, for example, a level adjustment, an inversion, an A / D conversion or a combination thereof. The preparation can also be implemented in whole or in part in the microprocessor 80.

By interrogating the door signal output 20, the microprocessor 80 can determine both the status of the status transmitter 30, which represents the status of the loading door, and also read back the status of the trigger signal MAIN_TRIGGER .

The monitoring unit 50 controls the mains switching relay 70, which can switch on and off a voltage supply for consumers with a mains voltage requirement in the household appliance, such as heating, drive motor, etc. The network switching relay 70 is activated by the monitoring unit 50 with a relay supply voltage V _HVR at the relay control output 56. The relay supply voltage V _HVR , which is made available to the monitoring unit 50, can advantageously be a PWM-modulated voltage in order to keep the power loss in the mains switching relay 70 low, especially if the mains switching relay 70 is only a lower one after switching Holding current required.

In addition, the monitoring unit 50 also detects the state of the input node 36 with its monitoring input 54.

With a signal at the HV relay input 16 of the door monitoring circuit 10, i.e. At the relay control input 52 of the monitoring unit 50, the microprocessor 80 basically controls the switching on and off of the mains switching relay 70 and thus the mains voltage supply for the said consumers. The monitoring unit 50 also links the release of the network switching relay 70 to the state of the input node 36, in such a way that the network switching relay 70 can not be switched when the loading door of the household appliance is open and thus also prevents the Mains voltage for the operation of critical consumers such as heating, drive, fan, etc. is available.

This hardware monitoring function thus represents an additional safeguard that none of the critical consumers can be in operation when the door is open.

Furthermore, with the aid of this monitoring function, in the embodiment shown, an optional test of the function of the microprocessor is also implemented, which is described below.

The microprocessor 80 can, as already described above, provide the trigger signal MAIN_TRIGGER at the trigger input 14.

If the trigger signal is missing, for example because the microprocessor 80 fails, then the monitoring unit 50 blocks the control of the mains switching relay 70, so that the mains voltage is prevented from being available for operating critical loads. A failure of the microprocessor 80 that is detected may consist of a physical error or that the software is no longer running correctly in terms of time and / or logic, for example because of a ROM error or incorrect timing.

This also ensures that if the microprocessor 80 functions incorrectly, none of the critical consumers can be in operation.

Since the microprocessor 80 also queries the status of the status node 36 at the door signal output 20, the microprocessor 80 can also use the trigger signal MAIN_TRIGGER to determine whether the signal chain from the status transmitter 30 to the input node 36 has certain errors, for example an interruption or a short circuit. If the microprocessor 80 provides a trigger signal MAIN_TRIGGER at the trigger input 14, then the state of the input node 36 also changes as a function of this trigger signal MAIN_TRIGGER. In the case of one of the errors mentioned, the state of the input node 36 does not correspond to one of the expected values that are to be expected based on the state of the state transmitter, the wiring through the pull-up resistor 32 and the pull-down resistor 34 and the state of the trigger signal MAIN_TRIGGER would be. The microprocessor 80 can thus determine whether an error is present by comparing the ADC_DOOR signal at the door signal output 20 with predetermined limit values.

Finally, the monitoring unit 50 provides an analog signal for the microprocessor 80 at the relay status output 58, which signal depends on the status of the input node 36 and the presence of a HV relay control signal HVR_ON at the HV relay input 16 and the relay supply voltage V _HVR and which the Microprocessor 80 is used to monitor the proper control of the network switching relay 70.

The signal for the microprocessor 80 at the relay status output 58 is processed, for example with a low-pass filter, so that it is a static signal even when the relay supply voltage V _{HVR is} a PWM-modulated voltage.

The signal ADC_9V_DOOR at the relay status output 58 indicates to the microprocessor 80 whether the mains switching relay 70 is switched or not.

The function of the door monitoring circuit 10 is illustrated below in connection with the description of a method of a door test routine that can be carried out with the aid of the door monitoring circuit 10 and that is based on the schematic flow diagram in FIG Figure 2 is described below. The operation of the door monitoring circuit is controlled by the microprocessor of the household appliance.

After being switched on, the microprocessor 80 can start 102 the door test routine at a defined point in time, when it is ensured that the necessary supply voltages are provided for the door monitoring circuit 10.

For this purpose, the microprocessor 80 reads out a configuration stored in the device in an initialization step 104. The configuration contains information about the door monitoring circuit 10, which is necessary to carry out the door test routine. This can be information about which door status transmitter 30 is installed in the device, for example a simple door switch 30a or a Hall sensor 30b. In addition, information on limit values for the status signals to be queried can be stored.

In a first step 110, the microprocessor switches off the MAIN_TRIGGER trigger signal for a time T _troff .

In a second step 112, the microprocessor checks whether the analog signal ADC_DOOR applied to the door signal output 20 lies between a lower limit value open_low_level_Toff and an upper limit value open_high_level_Toff for an open door.

If this is not the case, the microprocessor jumps to a fifth step 118. If this is the case, however, then the microprocessor checks in a third step 114 whether the analog signal ADC_9V_DOOR present at the door monitoring output 22 is less than the maximum limit value adc_max_door_opened for an open door Door.

If this is not the case, the microprocessor ends the door monitoring and outputs an error in a final step 128. If this is the case, however, then the microprocessor determines in a fourth step 116 that the door is open by setting the monitoring value DOOR_OPENED to 1 and continues the door monitoring with an eighth step 124.

In the fifth step 118, which the microprocessor starts when the condition of the second step 112 does not apply, the microprocessor checks whether the analog signal ADC_DOOR present at the door signal output 20 is between a lower limit value closed_low_level_Toff and an upper limit value closed_high_level_Toff for a closed door .

If this is not the case, the microprocessor ends the door monitoring and outputs an error in a final step 128. If this is the case, however, the microprocessor checks in a sixth step 120 whether the analog signal ADC_9V_DOOR applied to the door monitoring output 22 is between a lower limit value adc_min_door_closed and an upper limit value adc_max_door_closed for a closed door.

If this is not the case, the microprocessor ends the door monitoring and outputs an error in a final step 128. If this is the case, however, then the microprocessor determines in a seventh step 122 that the door is closed by setting the monitoring value DOOR_OPENED to 0, and the door monitoring continues with an eighth step 124.

In the eighth step 124, the microprocessor switches on the trigger signal for a time T _tron and continues with a ninth step 126.

In the ninth step 126, the microprocessor checks whether the analog signal ADC_DOOR applied to the door signal output 20 is either between a lower limit value open_low_level_Ton and an upper limit value open_high_level_Ton for an open one Door or between a lower limit value closed_low_level_Ton and an upper limit value closed_high_level_Ton for a closed door.

If neither one nor the other condition applies, this indicates that the signal chain from the state transmitter 30 to the input node 36, as described above, has an error. The microprocessor therefore ends the door monitoring and outputs an error in a final step 128. If, however, one of the two conditions applies, the microprocessor starts the door monitoring cycle again with the first step 110.

In an advantageous development of the inventors, the microprocessor 80 checks the door monitoring circuit 10 once for hardware errors before executing the routine described above, preferably after the device has been switched on. This function is explained below using the flow chart in Figure 3 describe.

As in Figure 3 shown, preferably between the initialization step 104 and the first step 110 of the door test routine Figure 2 , in a step 144 the trigger signal MAIN_TRIGGER is switched off and it is checked in a loop 148 during a period T whether the analog signal ADC_9V_DOOR present at the door monitoring output 22 is less than a limit value ADOR_max_startup . Once this is the case, the microprocessor 80 continues the door test routine with the first step 110.

If the signal ADC_9V_DOOR is not less than a limit value ADOR_max_startup " during the time period T. This indicates that a hardware error is present. The microprocessor 80 therefore terminates the door test routine and outputs an error in a final step 150.

The time T is chosen to ensure that all the necessary supply voltages for the door monitoring circuit 10 are available, but on the other hand the execution of the door test routine is not unnecessarily delayed. In the embodiment shown, the time T is set to 500 ms.

Are preferred for the limits ADOR_max_startup, open_low_level_Toff, open_high_level_Toff, closed_low_level_Toff, closed_high_level_Toff, open_low_level_Ton, open_high_level_Ton, closed_low_level_Ton, closed_high_level_Ton, adc_max_door_opened, adc_min_door_closed and adc_max_door_closed for different Types of state transmitters 30a, 30b store different values that can be read out when the device is started and stored in the microprocessor register for the execution of the door monitoring function.

Claims (5)

1. Household appliance with a microprocessor (80) and with a door monitoring circuit (10) with

   - an encoder input (12),

   - a state encoder (30), which is connected to the encoder input (12) and represents the state of a loading door of the household appliance,

   - an HV relay input (16),

   - a relay control output (56) for activating a mains switching relay (70) of the household appliance,

   - a monitoring unit (50), which is connected with the relay control output (56), the encoder input (12), the HV relay input (16) and the door monitoring output (22),

   wherein a pole of the encoder input (12) forms an input node (36) which is connected to the monitoring unit (50),
   wherein the microprocessor is embodied

   - to monitor the door monitoring output (22), and

   - to switch on the mains switching relay (70), to activate the HV relay input (16) of the door monitoring circuit (10) with an HV relay control signal (HVR_ON), and

   wherein the monitoring unit (50) is designed to activate the relay control output (56) as a function of the HV relay control signal (HVR_ON) on the HV relay input (16) only when the state encoder (30) indicates that the loading door of the household appliance is closed.
2. Household appliance according to claim 1, in which the state encoder (30) of the door monitoring circuit (10) is connected via a pull-up resistor (34) and a pull-down resistor (34) between a supply voltage (Vss) and ground (GND).
3. Household appliance according to claim 1 or 2, in which the microprocessor (80) is embodied to activate a trigger input (14) of the door monitoring circuit (10) with a trigger signal (MAIN_TRIGGER) which can change the state of the input node (36).
4. Household appliance according to one of claims 1 to 3, in which the door monitoring circuit (10) has a door signal output (20), which provides a signal as a function of the state of the input node (36).
5. Household appliance according to one of the preceding claims, wherein the household appliance is a washing machine, a tumble dryer or a washer-dryer.

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