FR2509946A1 - ELECTRONIC CONTROL CIRCUIT FOR DEVICE FOR DEFROSTING DOOR LOCKS, IN PARTICULAR FOR AUTOMOTIVE VEHICLES - Google Patents

Abstract

THE INVENTION CONCERNS AN ELECTRONIC CONTROL CIRCUIT FOR A DOOR LOCK DEFROSTING DEVICE, ESPECIALLY FOR MOTOR VEHICLES. IN THIS CIRCUIT, A CONTACT 1 OF THE LOCK OF THE CONTROL DOOR, JOINTLY WITH A THERMOMETRIC SENSOR R, TIMING COMPONENTS 20, 21 WHICH ENGAGE THE DEVICE R FOR HEATING THE LOCK FOR A DETERMINED DURATION DURING THE REPEATED ACTION OF THE DOOR HANDLE WITHIN THE LIMITS OF A PREDETERMINED TIME INTERVAL AND IN THE PRESENCE OF TEMPERATURES BELOW OR NEAR THE FREEZING POINT. APPLICATION TO THE DEFROST OF AUTOMOTIVE DOOR LOCK.

Description

The present invention relates to an electronic control circuit

an electrical device

  heating or de-icing of door locks, in particular

  motor vehicle, by means of a lock contact that can be actuated by the handle. When moisture gets into the lock of a car door because of rain or fog, this lock is seized in winter as a result of the frost that enters and it can not be opened by a key until the ice it contains has melted The defrosting of the lock can be carried out by means of an electric heating device, which is powered by the battery of the automobile and which is switched on when the button is pressed. handle To prevent overheating of this lock and battery discharge, some preventive measures should be taken for the heater to recover.

  by itself after a certain period of time.

  It is therefore an object of the present invention to provide a control circuit having electronic switchgear which engages the heater of the lock when the door handle is operated repeatedly within a time interval. predetermined; who

  triggers this device again after a period of

  complete; and which prevents deterioration of the lock of the door, the heating body and the battery of the automobile as a result of overheating and mishandling by unauthorized persons Advantageously, according to

  the essential characteristics of the circuit of the invention

  the contact of the lock controls, together with a temperature sensor, timing devices which engage the heater for a specified period of time when the door handle is actuated several times within a predetermined time interval and in the presence of lower temperatures

  or substantially equal to the freezing point.

  The circuit of the invention has the advantage of being easily manufactured and inexpensively,

  therefore to allow an economical production in series.

  During a normal opening of the door by an action-

  only in the case of temperatures above the freezing point, the heating device of the lock is not engaged. It is only after repeated actuations of said handle,

  closer to one another within the limits of a

  determined time, that the current coming from the

  of the automobile passes through the heating device

  when the temperature is below or close to

  freezing point To avoid a battery discharge

  frequently repeated actuation of this

  heating by non * authorized persons (eg

  example of children who play) is prevented by the

  Likewise, overheating the lock of the door

  the result of a false move is impossible.

  A rebound in the contact of the lock of the door

  does not exert any influence on this circuit, so

  that it is not essential to take measures

  particulars of switching to remove impulse

  delivered by the rebound of the contact.

  According to other advantageous improvements of the circuit of the invention this circuit may comprise two monostable timing devices, the first of which is biased during the first actuation of the contact of the lock, then releasing with a time delay and for a certain duration a second delay member monostable which is solicited by another impulse of the contact of the lock during the duration of excitation of the first delay member, in order to switch on the electric heating device, for a corresponding external temperature, so as to defrost the lock of the door ; to suppress twists in the contact of the lock, the two delay members can

  be connected to each other by a circuit of temporisa-

  comprising a voltage divider and a capacitor, said voltage divider being connected to the output of the first delay member as well as to the ground and its central area capable of receiving the ground potential through said lock contact and a diode, while the capacitor is at the tripping input of the second timer and receives the supply voltage through a resistor; said voltage divider can be designed to

  react to the temperature and for this purpose one of the

  or both may consist of a temperature-dependent resistor (hot or cold conductor or thermistor); and

  the resistance of the RC circuit

  capacitance) connected upstream of the second delay

  may be a temperature sensor for controlling the switch-on time of the

  lock heating according to the temperature.

  The invention will now be described in more detail by way of non-limiting example with reference to the accompanying drawing in which: Figure 1 is a diagram of an assembly providing control of the heating device of the lock; FIG. 2 illustrates by a diagram an exemplary embodiment of an uncomplicated and inexpensive circuit and

  FIG. 3 is a group of diagrams of im-

pulses of the circuit of Figure 2.

  FIG. 1 represents a door lock contact 1, a monostable multivibrator 2, an organ

  time delay 3, an AND gate 4, a thermometer probe

  5, a second monostable multivibrator 6, a tran-

  switching sistor 7 and a heating resistor RH

  of the heating device of the lock.

  The AND gate does not pass a trigger pulse of the resistor RH until

  its three input wires 15, 16 and 17 allow the

  In FIG. 2, the two delay devices 20 and 21 consist of monostable multivibrators timers, they are connected to each other.

  the other by a capacitor C 3 and they consist

  respectively two comparators 22, 23 and 24, 25 which are each connected to a respective rocker 26 and 27 of type SR The duration of the pulse generated by each

  flip-flop is regulated by means of RC circuits

  capacity) R 1, C 1 and R 2, C 2 At the output of the first

  20, are connected a diode 30

  and a resistance R 5, which, together with a resistance

  The load resistance of this capacitor C bears the reference R. At the output of the second delay element 21, the switching transiter 7 and

  heating resistor R of the heating device.

  The pulse diagrams in FIG. 3 represent the shape of the voltage at points a, b, c,

  d and e of the circuit of Figure 2 in the presence of

  below and close to the freezing point, and

  temperatures above this freezing point.

  The pulse durations at the output of the first member 20 (point b) and the output of the second member 21 (point c) are respectively about 2 seconds and about

  seconds The operation of the circuit according to the invention

  It will now be explained with regard to the pulse diagrams of FIG. 3. When the door lock contact 1 is open, a positive potential

  is applied to point a through a resistance

  A diode 32 is in a blocking direction with respect to this potential and no current flows through the resistor R 6 When the contact 1 is closed for a short time, the point a is connected to the ground via This contact causes the timer 20 to trip, hence the generation

  a rectangular pulse lasting about 2 seconds

  condes at its output b The duration of this pulse is de-

  terminated by the circuit RC R 1, C% * Concomitant with the

  closing the contact 1 of the lock, the point c is connected

  grounded via the diode 32 and a resistor R 4 A positive potential is applied at the point d via the resistor R 3,

  so that the capacitor C 3 is charged by the resistors

  R 3 and R 4 to the totality of the potential difference

between the most and the mass.

  When the contact 1 of the lock is triggered, that is to say open again, the connection to the ground of the point c by the resistor R 4 disappears.

  positive voltage is applied at point c through

  the output of the first delay element 20, the diode 30 and a resistor R, the amplitude of this positive voltage is determined by the divider of

  voltage comprising the resistor R 5 and the resistor RT de-

  during the weather For the most part, the duration

  of the capacitor C 3 is determined by the

  of time R 5 and C 3 and preferably it reaches about 30 ms This duration of about 30 ms is necessary

  to suppress negative effects due to bouncing

Contact 1.

  If the contact 1 of the lock is closed a second time during the determined pulse duration

  by the timer 20, the point c is again

  veal connected to the ground via the resistor

  R 4 and diode 32 This results in the application of a negative voltage at point d via the

  capacitor C 3 When this drop in voltage is suf-

  important to reach below the triggering level of the second timing member 21, the latter is triggered and there occurs at its output e a pulse of about 60 seconds which, determined by the circuit R 2, C 2, solicits the heating resistor RH via the switching transistor 7 to defrost the lock With respect to the resistor RT, the resistor R 5 is dimensioned such that, in the presence of temperatures below and close to the point of

  freezing point, the voltage drop at point d exceeds nega-

  the triggering threshold of the second delaying member 21, which corresponds substantially to the third

of the supply voltage.

  At temperatures above the point of

  freezing, the resistance RT (hot conductor) pre-

  feels a lower value, so point c can only absorb a lower positive voltage after

  the first actuation of the contact t and the fall of

  sion at point d is no longer sufficient, in the new action

  said contact 1, to reach the trigger threshold

  the delay element 21, so that no pulse is generated at the point e and that the resistance RH is also not solicited, as is apparent from the

  right side of the diagrams in Figure 3.

  Preferably, the hot conductor is incor-

  pored in thermal contact in the lock of the door.

  This prevents the lock from overheating because the

  The hot-plugger only allows a reclosing of the lock heating device

  cooling down to the freezing range

  tion, and the voltage drop at point d can again exceed negatively the trip threshold If this proved impossible for reasons of space, it is also possible to individually heat resistance RT (hot conductor) at the same time as the heating device, so that a new reclosing of the heater of the lock

  only after a certain period of cooling

dissement.

  In the context of the invention, it is also possible to control the duration of the heating pulse at point e as a function of the temperature In this case,

  the resistance R 2 of the circuit RC of the second time

  porization is carried out in the form of a resistance

depending on the temperature.

  The circuit described above is only one embodiment of the invention, which is not limited to this example On the contrary, many modifications can be made to the realization of this circuit and the choice and arrangement of its elements

  switching, without departing from the scope of the invention.

Claims (1)

1 circuit for controlling an electric device for heating door locks, particularly for motor vehicles, by means of a lock contact actuated by the handle, circuit characterized in that said contact (1) of the lock of the control door, together with a temperature sensor (RT), of the delay elements (20, 21) which engage said heating device (RH) for a predetermined period of time during the repeated actuation of said handle within the limits of a predetermined time interval and in the presence of temperatures below or close to the freezing point. 2 circuit according to claim 1, characterized in that it comprises two monostable timing devices (20, 21), the first (20) is biased during the first actuation of the contact (1) of the lock of the door and releases then with a time delay and for a certain duration a second single-stage delay member (21) which is biased by a new impulse of the contact of the lock during the duration of excitation of said first member (20), in order to switch on said provision - Electric heating system (RH) in the presence of a corresponding external temperature, in order to defrost the lock of the door. Circuit according to one of Claims 1 and 2, characterized in that the two delay elements (20, 21) are connected to one another to remove the re-bursts from the contact (1). other by a delay circuit comprising a voltage divider (R 5, RT) and a capacitor (C 3), said voltage divider (R 5, RT) being connected to the output of the first delay member (20) as well as to ground and its central area receiving the ground potential via said contact (1) and a diode (32), while said capacitor (C 3) is at the trip input of second delay member (21) and receives the supply voltage via a resistor (R 3). 4 Circuit according to any one of Claims 1 to 3, characterized in that the voltage divider (R 5, RT) is designed to depend on the temperature, one or both of the resistors being this effect of the temperature-dependent resistors' conductors hot or cold). Circuit according to any one of the claims   1 to 3, characterized in that the resistance (R 2) of the RC circuit (R 2, C 2) connected upstream of the second delay element (21) consists of a thermometric probe,   in order to control the switching-on time of the dis-   positive (RH) lock heating according to temperature.