EP0776496B1 - Circuit for the drive of at least one electrically actuated magnet - Google Patents

Description

The invention relates to a circuit arrangement for control at least one electrically controllable magnet with a targeted drive performance, by which the magnet is a switching element in a desired Switching position switches in which the switching element is held is.

Document FR-A-2 600 150 describes the structure and the control of a bistable solenoid valve with one valve actuator, with the help of two Valve positions are adjustable.

Circuit arrangements according to the preamble of the claim 1 are for the control of multi-temperature refrigerators known bistable solenoid valves, which to control the flow of refrigerant to the arranged in compartments of different temperatures Serve evaporators. Such, used in cooling devices upcoming circuit arrangements have on the input side one for evaluating control parameters, such as temperature controller signals serving logic part, with its Help a triac or two on the circuit output side anti-parallel thyristors for loading of the bistable solenoid valve with the corresponding one Control power are controlled. With these Semiconductor components can result from mains voltage peaks a so-called in its supply voltage "Overhead ignition" occur, through which an unwanted Control pulse generated on the solenoid valve is, which then this from a desired, by the temperature controller signals dependent valve position in its opposite switching position has been transferred. Such one Occurrence can result in the temperature in a freezer of a two-temperature refrigerator rises above the permitted value, so that the stored therein Good, at least in appearance and taste is impaired while on the other hand a temperature drop in the refrigerator compartment of the device can cause this can that with chilled liquid containers be destroyed.

The invention has for its object a circuit arrangement according to the preamble of claim 1 to improve that in a simple way inadvertently caused a change of position Switching position of the electrically controllable as required Magnet is avoided.

According to the invention, this object is achieved by that the magnet after switching the switching element in the desired switching position at predetermined time intervals repeated with this switch position Corresponding drive performance at least in the short term is acted upon.

The solution according to the invention ensures that the electrically controllable magnet without additional Monitoring and related evaluation measures always held securely in its required switching position is so that unwanted, possibly to damage leading misalignments of the electrically controllable magnet are reliably prevented.

According to a further preferred embodiment of the object whose invention is intended to act upon of the magnet with drive power semiconductor components are provided, which after switching of the switching element in the desired switching position in predetermined time intervals repeated with a Provision of the control signal serving the control power are acted upon.

With a solution of this kind, it is possible in particular inexpensive and simple way to control an electromagnet, the control elements in the event of damage quickly are interchangeable.

A particularly simple concept for a logic circuit, with which at the same time the possibility of occurrence a malposition of the electrically controllable Magnet is minimized, if after a another advantageous embodiment of the object the invention provides that the time intervals are of the same length between the control signals.

According to a further preferred embodiment the subject matter of the invention provides that the Driving power through the half-waves of an AC voltage is formed, of which a plurality of each directly are generated in succession as a signal sequence, where two consecutive signals are followed by one long time compared to the cycle time of the half-waves are spaced from each other.

With a solution of this kind, the solution is as required Switch position of one actuated by the electromagnet Switching element ensured in a sufficient manner, at the same time the energy consumption by the circuit arrangement and their stress is minimized.

Particularly precisely due to the relevant influencing factors A circuit arrangement is driven as required, if according to a last advantageous embodiment of the The object of the invention is that the generation the control signals automatically by a control unit depending on at least one control parameter are generated.

Fig. 1

ein Zweitemperaturen-Kühlgerät bei geöffneten Türen mit einem Kühlfach und einem Gefrierfach, deren Temperaturen durch eine elektronische Regeleinrichtung gesteuert sind,

Fig. 2

einen Ausschnitt der elektronischen Regeleinrichtung mit einer elektronischen Schaltungsanordnung zur Erzeugung von Ansteuersignalen zur Sicherung der bedarfsmäßigen Schaltposition eines bistabilen, den Kältemittelfluß zu den Kältefächern steuernden Magnetventiles,

Fig. 3

die zu den beiden Schaltpositionen des bistabilen Magnetventiles korrespondierenden Ansteuersignale, jeweils schematisch aufgetragen auf einer Zeitachse.

The invention is explained in the following description using the example of a two-temperature cooling device shown in simplified form in the accompanying drawing. Show it:

Fig. 1

a two-temperature refrigerator with open doors with a refrigerator compartment and a freezer compartment, the temperatures of which are controlled by an electronic control device,

Fig. 2

1 shows a section of the electronic control device with an electronic circuit arrangement for generating control signals to secure the required switching position of a bistable solenoid valve that controls the flow of refrigerant to the cold compartments,

Fig. 3

the control signals corresponding to the two switching positions of the bistable solenoid valve, each schematically plotted on a time axis.

1 is a refrigerator and freezer combination 10 shown, the heat insulating housing 11 two through a heat-insulating partition 12 thermally separate, vertically one above the other and lockable storage compartments with separate doors 13 and 14 having. The higher one is with the Door 13 lockable storage compartment designed as a cooling compartment 15, which with one another in vertical intervals arranged, for serving refrigerated shelves 16 is equipped. The other below the refrigerator compartment 15 arranged through the heat-insulating partition 12 of them separate and lockable with the door 14 Storage compartment 13 designed as a freezer compartment 17, which is used to hold frozen food with drawer-like extendable freezer containers 18 is equipped.

Both the refrigerator compartment 15 and the freezer compartment 17 are to maintain its intended storage room temperature equipped with evaporators, not shown, which in a refrigeration circuit, also not shown are included, within which the evaporator compressor supplying liquid refrigerant is arranged, which operates intermittently is, the on and off phases of the compressor from the temperatures prevailing in the storage compartments are dependent. These are from temperature sensors, not shown recorded and in one to an electronic Evaluation logic 19 belonging to the control device on the one hand to displayable in temperature display elements Values prepared and on the other hand in a circuit arrangement 30 further processable digital signals "A" and "B" processed (see Fig. 2).

As can be seen in particular from FIG. 2, they represent the output side digital signals present at the evaluation logic 19 "A" and "B" input signals for the circuit arrangement 30, with a positive output signal "A" signals a refrigeration request for the refrigerator compartment 15, while a positive output signal "B" is a refrigeration request means for the freezer compartment 17. That at the Evaluation logic 19 output signal "A" is closed its further processing via a current limiting resistor 30.1 fed to an input of a NAND gate 31, its second input with an input signal "C" is applied. This can affect both the voltage level logic "1" as well as the voltage level logic Accept "0", each by one on its two Inputs merged NAND-Schmitt trigger 32 are generated, the duration of the respective signal state is of different lengths. This period of time in the case of logical level "1" by the charging time by an ohmic resistor 33 and one with its cathode at ground potential connected capacitor 34, the RC element for Determining the direction of the charging current with its cathode connection coupled to ohmic resistor 33 Diode 35 is connected upstream. The duration of the logical Level "0" for the input signal "C" is through an RC element determines which of the capacitor 34 and one Ohmic resistor 36 is formed, the resistance value to generate a longer period of time for the logical level 0 clearly above that of Ohm's Resistor 33 lies.

Furthermore, the evaluation logic 19 is connected with its output providing the digital signal "A" via a diode 37 coupled with its anode connection to this output to a circuit section belonging to the circuit arrangement 30, which serves to evaluate the AC voltage usually required for the operation of household appliances, which is generated by a with "L" designated line pole of the AC voltage network is coupled to a resistor 38 serving for current limitation for the operation of logic modules. This is connected to two diodes 39 and 40 arranged in series, the diode 39 being connected with its cathode connection to the positive pole of a direct voltage source U _B , while the other diode 40 is connected with its anode connection to ground potential, which at the same time has the zero pole "N" of AC voltage. The potential which arises at the junction between the diodes 39 and 40 arranged in series is fed on the input side to a NAND-Schmitt trigger 41, the two inputs of which are connected to one another. The output of the NAND-Schmitt trigger 41 is connected to the cathode connection of a diode 41.1, which is connected on the anode side to an input of a NAND-Schmitt trigger 42, which at the same time is also supplied with the output signal "B" of the evaluation logic 19. The signal "C" is present at the other input of the NAND-Schmitt trigger 42. The output of the NAND-Schmitt trigger 42, like that of the NAND-Schmitt trigger 31, is connected to the base of a pnp transistor 43, the emitter connection of which is connected to a direct voltage supply U _B , while its collector connection is connected via an ohmic resistor which limits the collector current Resistor 44 is connected to ground potential. Between the collector connection of the pnp transistor 43 and the ohmic resistor 44, the gate connection connected to a current-limiting series resistor 44.1 for tapping the ignition current of a triac 45 is arranged, with its second main electrode connection one to the line pole "L" one 230 volt AC voltage coupled bistable, two flow paths switching electrically controllable solenoid valve 46 is connected. The other main electrode of the triac 45 is connected to the zero pole "N" of the AC voltage supply.

In the event that for the refrigerator compartment 15 due to the therein increased temperature, there is a need for cooling by a cooling air temperature already mentioned at the beginning monitoring sensor detected and then signal generated by the temperature sensor from the Evaluation logic 19 to a logic "1" at its output "A" implemented. This level, which corresponds to the corresponding Input of the NAND-Schmitt trigger 31 is supplied, causes along with a like, through the signal "C" generated level at the output of the NAND-Schmitt trigger 31 one based on the serving as switch 43 pnp transistor 43 acting low level (logic "0"), which puts it in a conductive state.

The input signal "C" at the input of the NAND-Schmitt trigger 31, which is due to the wiring of the NAND-Schmitt trigger 32 is generated in an automatic manner only during the charging time of the capacitor 34 above that Resistor 33 as high level (logic "1") while it for the discharge time of the capacitor 34 via the resistor 36 has low level, both level states by exceeding or falling below a predetermined Switching threshold at the NAND-Schmitt trigger linked at the beginning 32 are effected.

The output signal of the NAND-Schmitt trigger 31 also becomes still by evaluating the AC line voltage to operate the fridge-freezer combination (e.g. 230 Volts) influenced by the negative half-wave this sinusoidal AC voltage, both diode 40 as well as the diode 37 in the conductive state is, so that on the signal "A" acted upon Input of the NAND-Schmitt trigger 31 for about the duration this half wave is low, causing the output of the NAND-Schmitt trigger 31 goes to high level and thus pnp transistor 43 blocks. In contrast, the positive Half wave of the sinusoidal AC voltage the one originally at the exit of the NAND-Schmitt trigger 31 set low level have no influence, so that the pnp transistor 43 thus switched through and the thereby ignition of the Triacs 45 caused a current supply to the bistable solenoid valve 46 causes where by the desired change in position of the valve actuator to redirect the refrigerant to the evaporator of the Cooling compartment 15 takes place.

The influence is through the wiring of the output "A" of the evaluation logic 19 and the input of the NAND-Schmitt trigger 41 with the diode 37, which prevents arranged in the reverse direction with respect to the exit "A" is because there is one that does not require cooling Low level at output "A" due to the positive half wave no high level at the sinusoidal AC voltage Input of the NAND-Schmitt trigger 31 can be pending uncontrolled turning on of the transistor 43 would cause.

For the period of time for which the signal "C" has a high level and the cooling compartment 15 is requesting cold, the solenoid valve 46 is corresponding to the positive, at equal intervals successive half-waves of the sinusoidal AC voltage, as shown in FIG. 3 under position "1 "are applied, whereby the valve actuator of the solenoid valve 46, which serves as an armature for the electro-magnets, is held in the desired switching position as required. Corresponding to the length of time, which is denoted in FIG. 3 under position "1" by t _P (= duration of the drive pause) and essentially corresponds to the discharge time of the capacitor 34, the signal "C" has a low level, which results in the output of the NAND-Schmitt trigger 31 sets a high level, which puts the pnp transistor 43 in the off state, so that the solenoid valve 46 is not acted upon for this time. After this period of time t _P , the signal "C" again has a high level, as a result of which the solenoid valve 46 is again subjected to drive power in the form of the positive half-waves of the mains AC voltage supply, in order to ensure that the valve switching element of the solenoid valve 46 is returned to the required switching position is if this had been removed from the triac 45, for example as a result of so-called "overhead ignition". In this case, a time of 30 s has already been found to be a usable variable for the control pause t _p , while a time of 70 ms for the duration of the signal "C" has proven to be favorable.

Should there be 17 refrigeration requirements for the freezer compartment, see above this is done by a at the output "B" of the evaluation logic 19 applied high level signals, which via a current limiting resistor 30.2 on the input side, as well as the signal "C" at the NAND-Schmitt trigger 42, which when there is a cold request for the freezer compartment 17 to control the pnp transistor 43 and thus also for targeted control of the solenoid valve 46 via the triac 45. Whose drive power is in the case of cold demand for the freezer compartment 17 due to the negative Half waves of a sinusoidal AC voltage, such as 3 under position "0", educated. The course of the sinusoidal AC voltage through the series connection of the diodes 39 and 40 rated, by switching the NAND-Schmitt trigger 41 only in connection with the diode 41.1 the negative half wave at a corresponding level of signal "C" at the output of NAND-Schmitt trigger 42 a low level and thus switching the pnp transistor through 43 is able to effect, while the positive Half wave of sinusoidal AC voltage no control of the transistor serving as an electronic switch 43 can cause. Through the wiring on the output side of the NAND-Schmitt trigger 41 with the diode 41.1 is the evaluation logic when output "B" is high 19 causes the corresponding input signal at the NAND-Schmitt trigger 42 the output signal of the NAND-Schmitt triggers 41 follows while at a low level at output "B" it is ensured that this is independent from the output signal of the NAND-Schmitt trigger 41 at the input of the NAND-Schmitt trigger 42 is retained. Analog to the control of the solenoid valve 46 with the positive half waves according to the position shown in FIG. 3 "1", the negative half-waves (Fig. 3 position "0") as control power only for the duration of one High level at the output of the NAND-Schmitt trigger 32 supplied to the solenoid valve 46.

In order to be able to ensure that the valve switching element of the solenoid valve 46 is in the desired position after switching the valve switching element serving as the armature into the appropriate switching position determined for the freezer compartment 17, this is from time to time in the form of a signal sequence serving as control power of the negative half-waves of the sinusoidal AC voltage, the length of the signal sequence being determined by the duration of the high level for the signal “C” and the period t _P between the signal sequences being determined by the duration of the low level for the signal “C”.

Claims (5)

1. Circuit arrangement for the drive control of at least one magnet, which is electrically controllable in drive, by a target-oriented drive control power, by which the magnet switches a switching member into a desired switch position, in which the switching member is retained, characterised thereby, that the magnet (46) after its switching of the switching member over into the desired switch position (15, 17) is repeatedly acted on at least briefly at predetermined time intervals by a drive control power corresponding with this switch position.
2. Circuit arrangement according to claim 1, characterised thereby, that for action on the magnet (46) by the drive control power, semiconductor components (45) are provided, which after the switching-over of the switching member into the desired switch position (15, 17) are acted on repeatedly at predetermined time intervals by a drive control signal serving to prepare the drive control power.
3. Circuit arrangement according to claim 2, characterised thereby, that the time intervals between the drive control signals are dimensioned to be equally long.
4. Circuit arrangement according to claim 1 or 2, characterised thereby, that the drive control power is formed by the half-waves of an alternating voltage, from which half-waves a plurality one immediately after the other is produced each time as signal sequence, wherein two successive signal sequences are spaced one from the other by a time duration which is long by comparison with the cycle time of the half waves.
5. Circuit arrangement according to claim 4, characterised thereby, that the drive control signals are produced automatically by a drive control unit (32, 33, 34, 35, 36) in dependence on at least one drive control parameter.

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