DE2756722C2 - Control circuit for an electric motor fed from a voltage source - Google Patents

Description

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gnal directly to the control input of the switching element (34, 33) or to the supply input (31) of the assembly (30).

8. Control circuit according to claim 2, characterized in that the switching element (34, 33) through a control signal is controlled, which is based on the The invention is based on a control circuit for an electric motor according to the features of the preamble of claim I.

In such known from DE-OS 24 07 812 The control circuit is a wiper motor in a first operating mode, namely the normal wiping mode, alone via the operating switch, in the second operating mode, namely intermittent operation, on the other hand via a switching element controlled by a wiper pulse generator. The parking position switch is a changeover switch in this version formed, which in normal wiping operation when entering the parking position of the motor operating circuit switches to engine braking circuit. The park-

jibuungüoviiuitX '] uiiiviunviu aiou z.uiiav, iiai ui.ii ινιυιυι * operating current and briefly later switches the armature winding of the motor short. In the second operating mode, namely intermittent operation, the switching element, namely a transistor-controlled relay, is reset via the park position switch in the park position, which then switches from molar operating current to motor

braking current switches while in the first operating mode The operating current and the motor short-circuit current flows via the park position switch Interval operation of the parking position switch only as a signal switch. This finish was chosen so not the contacts of the parking position switch in intermittent operation, but that of the relay.

It has now been shown that due to this circuitry different shutdown of the wiper motor s the wiper blades different parking positions take in. This is perceived as annoying by the driver and the object of the invention is therefore based on a control circuit of the type mentioned by simple circuitry measures to improve so that after switching off the electric motor regardless of the previously set operating mode the same parking position is always taken without affecting operational safety will.

This is achieved according to the invention by the features in the characterizing part of claim 1

The invention is based on the idea that the circuitry is the same in both operating modes Way to realize the parking position. In principle, there would have been a possibility, including the second operating mode the electric motor via the parking position switch switch off, but this would reduce the service life of the parking position switch out which is not designed for frequent switching, as occurs in interval operation.

A very simple embodiment is characterized by claim 2. The principle could also be formulated in this way be that when switching off the electric motor by a control signal, a memory is set, which is in the Park position of the electric motor is reset, this memory the second power supply circuit maintains.

This also makes the difference to the circuit according to DE-AS 24 36 302 clear, in which also in both operating modes from a relay to be assumed as a switching element from operating current to braking current is switched, so that the aforementioned problem with regard to the exact parking position is not given is. In this version, however, the switching element is always switched through even in normal wiping operation, which is connected in series with the operating switch This circuit has the serious disadvantage, that in the event of a relay defect wiping operation is no longer possible at all, while in the case of the invention Switching at least the wiping operation can be maintained via the operating switch can, however, the wipers are no longer automatically stored in the parking position.

In addition, the wiring effort in this circuit is considerable. The wiring effort leaves be reduced considerably by the measures according to claims 2 to 6, because then individual lines can be used as operating current or braking current lines as well as control signal lines

In a first embodiment, the control signal is derived from the counter electromotive force and tapped on the first power supply circuit. A line thus fulfills two functions. The reset signal the parking position switch is also connected to the switching element via a reset line supplied, whereby the brake circuit is also closed via this reset line. These too Line is therefore used several times

In a particularly preferred embodiment, the control signal is transmitted via the series connection of a resistor and a switch diode from the output of the switching element, which is connected to the electric motor is, connected to its control input resistor and switch diode act as a self-holding circuit. The switching element remains activated even if the electric motor is connected to the operating voltage source again is connected and the control signal is omitted. The switch diode is blocked and thus the self-holding circuit deleted as soon as a reset signal of the parking position switch via a diode on the common Connection point between resistor and switch diode is fed.

Comparing the circuit according to the invention with the embodiment according to DE-OS 24 07 812, it results that the solution of the problem can be achieved with a resistor and two diodes without am Other changes are required on the operating switch or the pulse pulse generator. You can even do that there is no need for a line from the parking position switch to the positive connection of the supply voltage source. as Parking position switch is a simple closer instead of a changeover switch, it is also essential that if the parking position switch is designed as a switching disk with a contact spring, only one contact segment with a circumferential angle of about 15 ° is necessary, while in the execution according to the DE-AS 24 36 302 a contact segment with a circumferential angle of almost 360 ° is required.

An even simpler embodiment is given if the control signal for the switching element is from the operating switch is triggered. No changes need to be made to the operating switch if it is already the switching sequence has parking position-interval operation-normal wiping operation. It is with the known Execution according to DE-OS 24 07 812 only as a coupling element, a resistor or a diode to switch between the output of the switching element and the input of the pulse generator, so that again a self-holding circle is formed. With a single additional component, the initially mentioned object can be achieved, in turn, the parking position switch can be constructed more simply and there is no line to the parking position switch.

So far, the invention based on DE-OS 24 07 812 using the example of a control circuit for a wiper motor with a wiper pulse generator explained.

However, the invention can also be used sensibly with other actuators. For this reason, the claims generally speak of two operating modes and the wiping pulse generator is referred to as an assembly which determines the second operating mode. In the following, however, the invention is again explained on the basis of a wiper motor circuit.
In the F i g. 1 to 4 four different circuit variants are shown.

In Fig. 1, 10 denotes the wiper motor of the two control inputs 11 and 12 for different ones Has wiping speeds, during which one connection 13 is connected to ground. From the electric motor 10, a switching disk 14 is driven with a contact segment 15, which with a contact spring 16 cooperates. In the parking position shown, the contact spring 16 is with the contact segment 15

Ground connected. The contact spring and contact segment form the parking position switch.

The operating switch 20 has two movable, mechanically coupled switching bridges 21 and 22. One switching bridge 21 connects the positive Po in switching positions I, II and III! the voltage source Via corresponding control lines with the control input 31 of a pulse generator 30 or the control inputs 11 and 12 of the electric motor. The other switching bridge 22 connects in the switching positions 0 and I the output 32 of the pulse generator 30 with the control input 12 of the electric motor.

The overall designated 30 wiper pulse generator has a switching element, which consists of a relay 33 and a this relay controlling transistor 34 consists. The relay 33 actuates a changeover switch 35, one of which Fixed contact 36 is connected to the positive pole of the voltage source, while the other fixed contact 37 is connected to the contact spring 16 of the parking position switch via a reset signal line 39 movable contact 38 is to be regarded as output 32 of the switching element.

The wiping pulse generator 30 has a first timing element 40 with the resistors 41, 42, the capacitors 43, 44, the diode 45 and the resistors 46 and 47 leading to ground. The electric motor can can be controlled in interval operation.

At the common connection point of resistor 41, capacitor 43 and capacitor 44 are several diodes 48 connected to the one fixed contact 37 of the switch 35 or the reset line 39 are connected to the parking position switch. The structure of this pulse generator is known as soon as the supply voltage is fed to the timing element 40 via the control input 31, the transistor is energized 34 the relay 33, so that from the positive pole of the voltage source via the contacts 36, 38, the output 32, the Sehalibrücke 22 operating current through the electric motor The electric motor 10 runs and the contact spring 16 lifts off the contact segment 15. Of the Capacitor 43 charges up via resistor 41, diode 45 and resistors 46, 47. If now after a wiping cycle via the contact spring 16 and the contact segment 15, the reset line 39 in the in F i g. 1 is reconnected to ground, this negative voltage jump is over The capacitor 43 and the diode 45 are transferred to the base of the transistor 34, which thus blocks the relay 33 switches the changeover switch 35 so that now the electric motor 10 via the parking position switch, reset signal line 39, contacts 37,38, output 32, jumper 22, control input 12 is short-circuited The changeover switch thus switches from the operating circuit to the braking circuit. To control the Transistor 34, the capacitor 43 must recharge again.

In the embodiment according to FIG. 1 is a second timing element 50 with resistors 51 and 52 as well as the Diode 53 and the capacitor 54 are provided, which via a second control input 55 from a button 29 can be triggered in the operating switch. This timing element is used to delay control of the electric motor 10 in the washing operation, after the pump 60 conveys washing liquid Also the structure and the mode of operation this delay time element is known. The function of resistor 70 is now essential, which could possibly also be replaced by a diode. This resistance is between the output 32 and the input 31 of the wiping pulse generator and serves as a coupling element for the formation a self-holding circle. This resistor 70 ensures that the relay 33 remains energized, too if only a short control pulse can be measured at control input 31.

The overall circuit according to FIG. 1 shows that the electric motor 10 can be controlled via two power supply circuits is. In one operating mode, namely the normal wiping operation, the control input 11 of the electric motor is 10 in the switch position II of the operating switch via the contact bridge 21 directly to the positive pole connected to the voltage source. In the other operating mode, intermittent operation, control input is 11 on the other hand, in the switching position I via the contact bridge 22 and the changeover switch 35 of the switching element to the Voltage source connected. It is now essential that the electric motor is only used to move into the parking position is generally fed via the second power supply circuit. This is done as follows:

If the operating switch is reset from switch position II to switch position 0, will be briefly positive potential is applied to the control input 31 Normal wiping operation, intermittent operation, parking position used to trigger a control signal. This control signal makes the transistor 34 conductive. The relay 35 switches over. There is now positive potential at output 32, once via the contact bridge 22 in the operating switch is fed to the control input 12 of the electric motor, via the resistor 70 but is also fed back to the control input 31. The transistor 34 remains conductive and the relay 35 energized until a reset signal is triggered by the parking position switch in the position shown, which via the Reset signal line 39 and the diodes 48 as well as the capacitor 43 and the diode 45 to the control input of transistor 34 is supplied. The electric motor is braked immediately by a short circuit. Outgoing from normal wiping operation, the pulse generator is definitely triggered when it is switched off or that Switching element controlled by the contradiction 70, a self-holding circuit is formed, which is only via the parking position switch can be deleted. Since the same process is also carried out in the other operating mode, intermittent operation, expires it is therefore ensured that the wipers have an identical parking control regardless of the operating mode take in. It should also be added that of course also when switching position II or III the wiping pulse generator is triggered for one wiping cycle. But this has no effect, because the Circuit across the switching bridge 22 is interrupted.

In the control circuit according to FIG. 2, the effect is used that the running electric motor 10 after Switching off the voltage source generates a counter-electromotive force which is used as a control signal for the Switching element is used. It is true that the operating switch according to FIG. 2 when switching off briefly the Switch position for intermittent operation passed through, but this signal is no longer used. When executing according to FIG. 2 thus plays the switching sequence of the operating switch not matter. In contrast, the output 32 of the switching element via the switching bridge 22 Counter-electromotive force supplied in the pulse generator when the operating switch is in the zero position fed directly to the base of the transistor via the series connection of the resistor 80 and the switching diode 81 so that this becomes conductive. The relay 33 becomes

7th

again energized and the switch 35 switches positive plus potential only at the operating switch, but not vcs potential on output 32nd resistor 80 and on the motor or the wiping pulse generator, so that none Switch diode 81 thus again form a self-holding corrosion problem. After all, it is a circle of a while. This self-retention can be of some advantage via the diode 83 in that known circuits be deleted, which are very easily modified between the common scarf 5 within the meaning of the invention point of resistor 80 and switch diode 81 can without significant changes to the wiping and the reset signal line 39 is connected. As soon as the pulse generator switch and motor are made namely, the contact spring 16 must be in the park position.

rests on the contact segment, the potential is applied to the- Finally, it should be noted that with

sem circuit point on the threshold voltage of the di- io of the concrete wiring in the motor vehicle the Veröde 83 reduced, so that the transistor 34 immediately supply voltage both after the ignition switch as locks. can also be tapped directly from the battery.

Between the circuit according to FIG. 1 and the execution but preferred is an execution in the entsprerung According to Figure 2 there are the following essential accordingly Figure 4 of the operating switch and thus the first Differences: 15 power supply circuit behind the ignition switch 92, the

In one case, the control signal in the operating switch, relay 33, and the fixed contact 36, so the second when another case triggered by the electric motor. In the case of the drive circuit, however, it is directly connected to the battery Execution according to FIG. 1 affects the control signal are closed. This prevents the wiper the timer 40, in the embodiment according to FIG. 2 takes effect when the ignition is switched off in one of the parkes directly to the transistor 34. The circuit 20 remains in a different position.

according to FIG. 2 is therefore completely independent of the state

this timing element, in particular the state of charge of the 4 sheets of drawings

Capacitor 43.

The circuit according to FIG. 3 shows a variant of the circuit according to FIG. 2 because the diode 83 through one of the Diodes 48 is replaced. The cost of components is now reduced further, but with this circuit variant the timing element 40 is also influenced, which may have to be re-dimensioned.

The circuit according to FIG. 1 shows an embodiment variant in which both a control signal of the operating sounder as well as the counter-electromotive force is used to switch the switching element through, because the counter-electromotive force is also transmitted to the control input 31 via the resistor 70 switched through. This could also apply to the specified switching sequence of the operating switch in this embodiment be waived. However, in the case of the pulse generator circuit shown, there is in particular a Through control of the switching element is not guaranteed when the counter electromotive force is a certain Falls below threshold. In order to remedy this disadvantage, an embodiment according to FIG. 4 elected are, in which the necessary high-ohmic resistance 42 is bypassed for reasons of time, in which the counter electromotive force directly via a resistor 90 and possibly a diode 91 in series to the connection point between resistor 42 and diode 45 or between diode 45 and resistor 46 is fed. Compared to the embodiment according to FIG. 2, the diode 83 can then be omitted.

In the embodiments according to the invention, the electric motor is operated in an identical manner in both operating modes braked This improvement over known circuits also brings considerable benefits Advantages with regard to the wiring effort, because individual lines both supply the operating current and Conduct braking current as well as control signals. The operating switch and the parking position switch can also be very simple, which results in further cost advantages. The advantages are all the more larger, the more operating modes are provided. So is - as shown - also for a two-stage operable Electric motor no third switching bridge required in the operating switch because all control inputs of the mo- tors and the wiping pulse generator are individually controlled with the same potential, namely the plus potential will. So this is in the switched-off state

Claims (12)

Patent claims: 1. Control circuit for an electric motor fed from a voltage source, in particular for one Wiper motor in motor vehicles, with a parking position switch and a multi-stage operating switch for setting several operating modes, with the electric motor in a first operating mode in a first power supply circuit via the operating switch, in a second operating mode in contrast, in a second power supply circuit via a switching element that is independent of the operating switch is connected to the voltage source, characterized in that the electric motor (10) after switching off via the operating switch (20) to move into the parking position is generally fed via the second power supply circuit. 2. Control circuit according to claim 1, characterized in that for moving into the parking position the switching element (34,33) is controlled through and a self-holding circuit via the switching element (34,33; 36,37,38) is closed, which can be resolved via the parking position switch (15, 16) 3. Control circuit according to claim 2, characterized in that the switching element (34, 33) through a control signal is controlled, which is derived from the counter electromotive force of the electric motor is derived. 4. Control circuit according to claim 3, characterized in that the control signal at the first Power supply circuit is tapped and via a switching bridge (22) of the operating switch (20) the switching element (33,34) is supplied. 5. Control circuit according to claim 2, 3 or 4, characterized characterized in that the self-holding circuit by the series connection of a resistor (80) and a switch diode (81) is implemented between the output (32) of the switching element (34,33) and whose control input are switched, the reset signal of the parking position switch (15, 16) via a diode (83, 48) to the common connection point between resistor (80) and switch diode (81) is fed in and the self-holding circuit is released by blocking the switch diode (81) will. 6. Control circuit according to at least one of the preceding claims, characterized in that that the parking position switch (15, 16) is connected to a switching path (37, 38) via a reset line (39) of the switching element (33, 34) is connected and via the parking position switch (15, 16), the reset line (39), a switching path (37, 38) of the switching element (33,34) and the switching bridge (22) of the operating switch (20) a braking circuit is closed. 7. Control circuit according to one of the preceding claims, characterized in that the Switching element (34, 33) part of an assembly determining the second operating mode, for example Operating switch (20) is switched through. 9. Control circuit according to claim 8, characterized in that the switching element (34, 33) is a component an assembly determining the second operating mode, for example a wiper pulse generator (30) and that via the operating switch (20) with the switching sequence Park position - second operating mode - the first operating mode, the operating voltage is connected to the input (31) of this module, ίο being between the output (32) of the switching element (34,33) and the input (31) of the assembly (30) a resistor (70) or a diode are connected as a coupling element, and that by the reset signal of the parking position switch (15, 16) the switching element (34,33) is reset. 10. Control circuit according to at least one of the preceding claims, characterized in that that the parking switch (15,16) is a normally open contact, which is connected to in the parking position the earthed motor connection (13) 11. Control circuit according to at least one of the preceding claims, characterized in that that the switching element has a relay (33) with a changeover switch, the movable contact of which (33) cooperates with two fixed contacts (36,37), of which one (36) to the positive pole of the supply voltage source and the other to the reset line (39) is connected, the movable contact (38) further via a switching bridge (22) of the operating switch (20) is connected to a control input (12) of the electric motor (10) and wherein all control inputs (11, 12) of the electric motor Another switching bridge (21) of the operating switch with the positive pole of the supply voltage source can be individually connected and, if necessary, the assembly determining the second operating mode via this further switching bridge (21) can be controlled. 12. Control circuit according to at least one of the preceding claims, characterized in that that the first operating circuit in series with the ignition switch (92), the second operating circuit on the other hand is connected directly to the battery.