DK148218B - CONTROL DEVICE FOR A CLIMATE - Google Patents

Description

148218

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a regulator for an air conditioner in which the room temperature is regulated by heating or cooling the air, with a room temperature measuring bridge, an overlay joint influenced by the differential signal and a temperature controller with a common input for a continuous heat and continuous cooling setting range. , whereby the input of the temperature controller is derived from the output of the overlay link.

With a control device of this kind known from DE-AS 25 40 169, the operating direction of the temperature controller input signal can be repolished by means of a switch, so that the control device is optionally suitable for heating and cooling operation of the air conditioner. However, in case of strong temperature fluctuations in the room to be air-conditioned, this requires a manual intervention. In an automatic operation of the switch depending on the temperature, there is a danger that the heating and cooling unit, after a switch from heating to cooling operation (and vice versa) due to inevitable delay times, will counteract each other. This is uneconomical.

20 German DE-AS 20 56 208 shows a control device from one of at least two separate units consisting of heating and / or cooling systems with a room temperature measuring bridge. Connected to the bridge are two due to a co-feedback (positive feedback) as Smith-triggering operating amplifiers whose output signal can only assume two different values, and at which time only one of the two heat and / or the cooling unit forming units switches on or off. The Smith triggers are bistable tilted joints and not overlay joints. The tilt joints only tilt when the temperature-instant flash value constituting a bridge signal exceeds or falls below a threshold value. However, the threshold values for the two tilt links are differently chosen and are both influenced by it by an adjustable resistance in the bridge adjustable setpoint. The choice of different threshold values for the two tilt joints gives a dead zone in which neither the cooling system nor the heating system is switched on. Aside from the fact that this dead zone changes depending on the setpoint setting, it is all about a two-point regulator which constantly performs permanent oscillations. That is, the temperature is alternating above or below the setpoint, which often feels uncomfortable. In addition, the frequent switch-on and shut-offs cause an early wear of the cooling or heating units or valves apart from the associated noise.

The invention has for its object to provide a control device of the aforementioned kind, in which security is not only achieved against an overlap of cooling or heating operation in a wide temperature range, but also where shuttles are avoided, and in which a rapid intervention is nevertheless ensured. of the control device for controlling deviations in room temperature and from the desired value.

According to the invention, this task is solved by the fact that the temperature controller contains, in a manner known per se, a continuous heat setting means and a continuous cooling setting means, between whose setting areas there is a dead zone, that the temperature controller input signal derived from the overlay link output signal is supplied. an overlay link affecting the decoupling step, the output of which, in the event of a change in the temperature controller's zone, changes its input signal changes from a lower limit value to a higher limit value and whose influence on the overlay link output signal can be set.

In this embodiment of the control device, the heating and cooling setting means of the adjusting means do not immediately close to each other due to the dead zone, so that the danger of heating and cooling counteracting each other is degraded. As the input regulator signal of the temperature controller and thus the input signal of the countercoupling stage increases within the dead zone, the resulting decrease of the output signal of the countercoupling step causes a corresponding decrease in the input signal of the temperature controller. Therefore, in the range between the limit values of the counter-coupling stage, a greater change in the temperature of the room to be air-conditioned is required to change the input signal of the temperature controller to a predetermined extent than outside this range.

As a result, the countercoupling step results in an enlargement of the dead zone between the heating and cooling adjusting means of the adjustment areas. By adjusting the influence of the decoupling step on the output of the overlay link, the total dead zone between the temperature of the room to be air-conditioned and the output temperature of the temperature controller can be adjusted accordingly to the data of the setting means and the regulation stretch (of the room to be air-conditioned) given that there is no excessively long interruption of the regulation process in the area of the death zone, and the temperature fluctuations are nevertheless quickly adjusted.

Thus, it can be ensured that the countercoupling step has a very large gain differential amplifier whose output over a counterclockwise resistor with parallel-coupled reverse diode is connected to its inverting input and over a 4AA1818 voltage divider resistor with its non-inverting input and one, at a reference potential. the output signal of the temperature controller is applied to the inverting input of the differential amplifier over an input resistor 5 whose resistance value is less than the resistor resistor value and the output of the counterclocking step is subtracted from an adjustable output of the voltage divider resistor.

By such a coupling of the differential amplifier, a retroactive non-coupling step is obtained, in which a setting 10 of the output of the voltage divider resistor enables the setting of the lower limit value of the output signal of the coupling stage output and of the equipment area so that the voltage divider resistance has a dual function. The reverse diode, on the other hand, causes a limitation of the upper limit value of the output signal of the switching step to the value of the reference potential.

Also, it is advantageous when the overlay link has a high gain differential amplifier coupled to a resistor with a first, its inverting input having the 20 one bridge output connecting input resistor and with a second, its inverting input having the output of the counter coupling stage connecting input resistor -inverting input of this differential amplifier is connected to the other output of the bridge. Hereby, by means of the two input resistors on the inverting input of the differential amplifier, the superimposing of the reference signal of the counter-coupling stage and the output signal is effected, whereby the relationships between the resistor value of the counter-coupling resistor and the input resistors determine the influence of the output signal of the counter-coupling signal output signal of the counter-coupling stage. This, in turn, affects the extent of the death zone change in dependence on the difference of the limit values of the counter-coupling step output signal. Therefore, to set this influence, one input resistor 35 may also be adjustable.

5 148218

Furthermore, it can be ensured that the cooling and heating setting means are each coupled to a high gain differential coupler whose non-inverting inputs are both supplied with the input signal derived from the overlay link 5 and each of the inverting inputs is connected to an input an upper and a lower outlet of a voltage divider, and the outlet of the voltage divider and the equipment ranges of these differential amplifiers are selected such that the equipment area of the one adjusting member is in the equipment area of one differential amplifier and the equipment area of the other adjusting member is in the equipment area of the other differential amplifier. In this way, the heating and cooling setting means are operated one after the other in the control range of the temperature regulator input signal, even though their equipment limits are at equal values of their input signals. This has the advantage that the heating and cooling adjusting means have exactly the same characteristics if, for example, they control the flow of a heating medium and, on the other hand, the flow of a cooling medium, for example.

Furthermore, there may be a PI link between the overlay link and the temperature controller. The ΡΙ-link, on the one hand, enables accurate control of control deviations and, on the other hand, attenuates oscillations of the temperature setting input signal outside the dead zone.

A PI joint can be designed in a simple way by having an over-series ohmic resistor coupler and a high-amplifier differential amplifier coupled with an input resistor in front of its inverting input connected to the overlay link output.

Thus, it can be ensured that the inputs of the ΡΙ-joint differential amplifier are connected to the outputs of another bridge, which measures the air temperature in a duct / over which cooled or heated air is fed into the room from the cooling or heating setting means. which is to be air-conditioned and which processes the output signal 5 of the overlay link as the setpoint for this channel temperature. In this way, an auxiliary control circuit is obtained, which enables an even faster and more accurate regulation of control deviations.

The invention and its further embodiments are explained in more detail below by means of the drawing of a preferred embodiment illustrated in FIG. 1 is a block diagram of a room air conditioning device according to the invention; FIG. 2 is a more detailed diagram of a portion of the block diagram of FIG. 1 and 15 FIG. 3 is a diagram for explaining the operation of the temperature controller of the control device in FIG. 1 and 2.

In FIG. 1, the control device for controlling the temperature in a room 3 has a bridge 5, the difference signal of which is caused by a bridge signal in 20 depending on the room temperature over a conduit 7, one input of an overlay link 9, which is designed as a P-joint. The output signal of the overlay link 9 is applied to an input of a PI link 13 over a line 11. This output signal V-j is fed on one side over a line 15 to a temperature set 17 and on the other hand over a line 19 a counter-coupling step 21 is applied as an input signal. The upper limit value of the output signal of the step 21 is equal to the reference signal supplied by a line 23 from the bridge 5, relative to which the bridge tuning and the difference signal, respectively, are measured. The output signal of countercoupling step 21 which retains the upper limit value as long as signal V-j is below the linear equipment range of step 21, and assumes a lower limit value as soon as signal V- | exceeding the equipment area, the second input of the overlay link 9 is applied over a line 5 25.

The temperature controller 17 has two parallel signal channels which alternately act in dependence on the size of the signal supplied to the two signal channels simultaneously. The lower signal channel has a power setting means 27 with reverse heating adjusting means 29, while the upper signal channel also has a power setting means 31, however with after-cooling cooling setting means 33.

The heating setting means 29 is only operable below a value V ·] = V- | -j and causes a heating of the space 3 15 over a supply channel 35 to supply air with decreasing heat effect at increasing value of V ·), so that the temperature Ti of the supply air decreases with Vj to the value Vi 1. If the signal Vj further rises above the value V ^, at the beginning, neither the heating setting means 29 20 nor the cooling setting means 33 are operative, so that the temperature T of the supply air remains essentially unchanged at a value Tø · Only when the signal V, after passing through a dead zone 4.V, rises above the value V1, the cooling setting means 33 becomes active, while the heating setting means 29 remains inactive. The dead zone 4 V between the adjustment ranges of the two adjusting means 29 and 33 ensures that the adjusting means 29 and 33 respectively of the adjusting means do not work against each other. Therefore, the adjusting ranges of the pre-engaged power adjusting means 27 and 31 are displaced so much in relation to each other that the adjusting ranges of the adjusting means 29 and 33 are within the setting range of the pre-switched power adjusting means.

In the supply air duct 35 there is an additional bridge 37 which measures the supply air temperature T and, in relation to this temperature and the same reference signal as the bridge 5, measured the difference signal to a further input of the 5 Pi link 13 over a line 39, whereby PI The link 13 acts as a PI controller which compares the output signal of the overlay link 9 as a setpoint signal with the differential signal of the bridge 37 and, in response to a deviation between the two signals, regulates the temperature regulator 17 so that the deviation in 10 disappears. This internal auxiliary control circuit has a shorter delay time than the outer main control circuit in which the space 3 with a relatively long delay time lies.

The operation of the main control circuit in connection with the counterconnection step 21, the upper limit of which corresponds to the mean value of V-1 and V-2, is described below under the assumption that, for example, line 39 is disconnected, ie. the auxiliary control circuit is idle.

The steady state of the control course is entered at a value of the signal Vi, which is within the setting range of the heating setting means 29, that is, below the upper limit value corresponding to the dead zone center 21 of the counterclocking step 21. The output signal of the switching stage 21 is therefore at the upper limit value corresponding to 25. on line 23, while the bridge differential signal on line 7 is practically zero. Therefore, a signal corresponding to the reference signal on line 23 and the upper limit value is also passed over line 7. To facilitate understanding, the reference signal in the block diagram corresponds to the value of zero, so that the output of the overlay link 9 and also the deviation of the signals at the inputs of the Pi link 13 are zero. Therefore, the integration of the Pi joint 13 is at a value of the signal V- | come to a standstill which corresponds to the heating effect required by the room temperature to maintain the heating setting means 29.

As the room temperature drops due to external influences, a positive difference signal appears on line 7, so that the output signal of the overlay link 9 rises and the signal 5 We decreases due to the inverting function of the upper input of the PI line 13. Accordingly, the heating power of heating element 29 increases and the supply air temperature Ti increases further until the difference signal of bridge 5 has finally again become zero. The output 10 of the countercoupling step 21 hereby still remains at the upper limit value and equal to the reference signal respectively.

As the temperature in the room 3 rises from a stationary value in the heating setting range of the signal Vi less than Y1, the difference signal on the conduit 7 decreases; the output signal of the overlay link 9 also decreases and the signal We increases. The heat output of the setting means 29 decreases and a new stationary state is set, at which We are still less than Vn · As long as We are less than the mean of Vi 1 and V12, the output signal of the switch 20 stage 21 remains at the upper limit value.

However, if the room temperature due to external influences increases so much that Vj exceeds the mean value of Vn and V12, ie. the dead zone center, then the output signal of the counter-coupling step 25 is degraded. This, due to the sign change at the lower input of the overlay link 9 and at the upper input of the Pi link 13, immediately leads to a decrease of the signal Vi to near the dead zone center, so that the output of the counterclocking step 21 rises again to the upper 30 limit value. Therefore, to increase the signal We further, a greater increase in room temperature is now necessary. Only when the room temperature, by means of external nuisance influences, has risen so much that We have passed through the equipment range of the decoupling stage 21 to the lower threshold, does the signal v- | further, with the same rate of change depending on the room temperature, as under the equipment area of the step 21, until it has finally passed through the dead zone Λ V and exceeded the upper value V-j2f ° 9 5, respectively, the cooling setting means 33 reacts again to reduce the room temperature.

Exactly the same thing happens at a decrease in room temperature, just the working direction of all signals is reversed.

As a result, the basic dead zone Av conditional on the selection of the adjustment means 29 of the adjustment means 29 and 33 is therefore enlarged to an extent corresponding respectively to the gain and difference of the limit values for the output signal of the decoupling step 21 in its equipment range, taking into account the transfer coefficients of the transfer 15. therefore, by altering the equipment range and the difference of the limit values for the output signal of the decoupling stage 21 and / or for the said transfer coefficients, the effective width of the dead zone which lies 20 between the adjusting means 29 and 33 setting ranges, and the dependence between the temperature T in the channel 35 and the temperature in the room 3, according to the present conditions, such as the size of the room 3, the maximum heat and cooling power respectively of the available heating and cooling units and other influences are selected. in a simple way.

When the auxiliary control circuit with the bridge 37 is closed and operative, respectively, it supports the regulation process of the main control circuit in the direction of an acceleration.

30 Pig. 2 shows a detailed diagram of part of the control device of FIG. First

U8218 11

The bridge 5 consists of two resistors 41 and 43 in series equal to the operating DC voltage VB, resistances 41, 43 and three further in series of the DC resistor VB resistors 45, 47 and 49. The resistor 49 is an NTC resistor and serves to measure the 5 room temperature. The resistor 47 has an adjustable outlet and serves as a room temperature setpoint sensor.

The overlay link 9 consists of four resistors 51-57 and an amplifier A1 with very large gain. The outlet on the resistor 47 of the bridge 5 is connected over the line 7 and the resistor 51 to the non-inverting input of the differential amplifier A1. At the junction point of the bridge resistors 41, 43 which form one output of the bridge, the reference signal is taken and passed across the resistor 53 to the inverting input of the differential amplifier A1. The line 25 is also connected to the inverting input of the differential amplifier A1 over the resistor 55 and 15 and the output of the differential amplifier A1 over the adjustable counterconnection resistor 57.

The switching stage consists of resistors 59-65, a diode 67 and a differential amplifier A2 with very large gain. Furthermore, the connecting point of the bridges 41 and 43 is connected above the resistor 59 to the non-inverting input and over the resistor 61 to the output of the differential amplifier A2. The resistor 61, in comparison with the resistor 43, is high ohmic so that it does not act as a coupling resistor. Furthermore, the output of the differential amplifier A2 is connected above the resistor 63 to the inverting input of the differential amplifier A2, so that the resistor 63 acts as a countercurrent resistor. Then the wire 19 is above the resistance. 65 connected to the inverting input of the differential amplifier 30 A2. Parallel to the resistor 63 is a diode.

67 with its anode at the output and with its cathode at the inverting input of the differential amplifier A2. Resistor 61 has an adjustable outlet connected to line 25 and acts as a voltage divider resistor.

148218 12

The bridge 37 consists of two in series above the operating DC voltage Vg equal resistors 69 and 71 and two further in series resistors 73 and 75. The resistor 73 is also an NTC resistor and serves to measure the temperature of the supply duct 35.

The Pi joint 13 consists of three resistors 77, 79, 81, a capacitor 83 and a differential amplifier A3 with very large gain. The resistor 77 connects the junction points of the bridge resistors 73 and 75 with the non-inverting input of the differential amplifier A3. The resistor 79 connects the inverting input of the differential amplifier A3 with the connecting point of the bridge resistors 69 and 71 and with the output of the differential amplifier A1. The resistor 81 and capacitor 83 are in series between the output and the inverting input of the differential amplifier A3. Furthermore, the output of the differential amplifier A3 is connected to the line 19 and the resistor 65 is connected to the inverting input of the differential amplifier A2.

The power adjusting means 31 has a differential amplifier A4 with very large gain and resistors 85-89. The resistor 20 89 connects the output to the inverting input of the diffuser amplifier A4.

The power adjusting means 27 also has a differential amplifier A5 with very large gain and resistors 91-95, of which resistor 95 connects the output to the inverting input of differential amplifier A5.

Both power adjusting means 27 and 31 have a joint of three series resistors 97, 99 and 101 formed in voltage portions, which lies on the operating DC voltage Vg. Thereby, the connecting point of resistors 99 and 101 above resistor 30 87 is connected to the inverting input of differential amplifier A4, and the connecting point of resistors 97 and 99 is connected to resistor 93 to inverting input of differential amplifier A5. Furthermore, the output of the differential amplifier A3 over the line 15 and the resistor 85 and the resistor 91 respectively are connected to the non-inverting input of the differential amplifier A4 and A5 respectively.

5 The following table contains the data of the components in the circuit of FIG. 2, where the size indications correspond to the value of the components indicated by reference number.

r41 = r43 = r69 = r71 = R75 = 113 ° hm R45 = 110 ohms 10 R47 = 16 ohms r49 = R73 = 100 ohms / ° C (NTC) R51 = R53 = R59 = r65 = 22 kilograms R55 = 100 kilograms R57 = 500 kilohm 15 Rgi = 10 kilohm Rg3 = 484 kilohm r87 = r93 = 9 kilohm Rgi = 10 megaohm r89 = r95 = 11 kilohm 20 R97 = R101 “3 kilohm R99 = 5 kilohm C83 = 4.7 microfarad A1 = A2 = A3 = A4 = A5 = type LM201A; idle gain approx. 120,000 25 VB = 22 volts

The operation of the circuit in FIG. 2 with reference to FIG. Third

Since the resistors 41 and 43 are equal, the potential of the points of contact of the resistors 41 and 43 to the frame (-) is equal to 30 the half operating DC voltage Vg, ie. 11 volts. This value corresponds to the value of the said reference signal in relation to the frame and the potential of the operating voltage voltage negative current source, respectively.

When the inverting input of the differential amplifier A2 and the resistor 65 applied to the output signal V-j of the differential amplifier A3 exceeds the non-inverting input 5 of the differential amplifier A2 above the resistor 59 applied to the reference voltage of 11 volts, the difference amplifier A2 of the output amplifier 11 drops. The output voltage of the differential amplifier A2 decreases until the voltage Vj reaches the value Vi * 11.5 volts, ie. has passed 0.5 volts. The output voltage of the differential amplifier A2 then lies at the lower equipment limit of approximately zero volts of the differential amplifier A2. on the resistor 61 is then a voltage of approx. 11 volts.

On the other hand, when the output signal V-j falls below the non-invertebrate input of the differential amplifier A2 supplied reference voltage of 11 volts, the output voltage of the differential amplifier A2 tends to rise above this value of 11 volts. Therein, however, it is obstructed by the diode 67, which now becomes conductive, so that at both inputs of the differential amplifier A2 there is approximately the same voltage of 11 volts.

Therefore, the output voltage of the differential amplifier A2 is limited and thus the voltage at the output of the resistor 61 of the diode 67 upwards to the reference potential of 11 volts. Therefore, the reference potential of 11 volts independently of the setting of the output of resistor 61 forms the upper limit of the output of counterclocking step 21, while the lower limit value of this output is determined by the setting of the output of resistor 61, but cannot fall below the lower limit of amplifier A2. zero volts.

The voltage removed at the resistor 61 is superimposed by the resistor 55, with the inverting input of the differential amplifier A1 supplied from the resistors 41 and 43 above the resistor 53 by reference potentials. Therefore, at balanced bridge 5 and the upper limit value of the output signal of the counter-coupling stage 21, the output voltage of the differential amplifier A1 also equals 11 volts. On the other hand, if the output signal of the countercoupling step 21 is controlled from the upper to the lower limit value, the output voltage of the differential amplifier A1 increases to a value greater than 11 volts due to the inverting effect of the upper input of the differential amplifier A1.

Assuming that bridge 37 is also in balance, and both resistors 73 and 75 are equal, respectively, the output amplifier A3 output signal V- | below 11 volts at over 11 volts output voltage of the differential amplifier A1.

FIG. 3 shows the dependence of the output voltage Vgi and Vq2 measured in volts of the power setting means 27 and 31 and the temperature T in the supply air duct 35 of the value of the signal V- | in volts. The output voltages Vgi and Vq2 increase to the same degree linearly with ν ·, but are offset to a degree corresponding to the linear equipment range of the heating setting means 29 and the dead zone AV together. This offset is caused by the voltage divider 97-101 and here is equal to the difference between V12 = 11/5 volts and 6 volts, ie 5.5 volts, with AV = V- | 2 - V · 1 = 1 volts.

For the output voltage Vgi you get the relation 25 V01 = V! + (Vi - V97). £ || (1) whereby V97 is the voltage drop on resistor 97. With the specified resistance values, therefore,

Vqi = V] + (V! - 6V). (2) 148218 16

At V- | = 6 volts is therefore Vø-j = 6 volts »and at V- | = 10.5 volts is Vöi = 16 volts.

Similarly, V02 = Vt + (V! - (V97 + V99)). ||| (3) 5 and with the specified resistance values V02 = Vt + (V- | - 16V). . IJ. (4) i.e. at V | = 11p5 volts is Vø2 = 6 volts and at V-j = 16 volts Vø2 = 16 volts.

The linear setting range of the heating setting means 29 which determines the temperature Tj and is controlled by the output setting means 27 and the differential amplifier A5 output voltage V1, respectively, is now chosen such that it lies between V1 = 6 volts and V1 = 16 volts. and therefore between Vi —6 volts and Vi = 10.5 volts. Correspondingly, the linear setting range of the switching adjustment means 33, which determines the temperature T2 and is controlled by the output voltage V02 of the power setting means 31 and the differential amplifier A4, respectively, is chosen so that it lies between V02 = 6 volts and V02 = 16 volts and therefore also between Vi = 11.5 volts 20 and Vi = 16 volts. As a result, between the linear setting ranges and the equipment ranges of the setting means 29 and 33, respectively, a dead zone of 1 volt is obtained in relation to a change of Vi, which in its effect on the total output temperature T of the temperature controller 17 in dependence 25 on the temperature in the room 3 can is affected by the magnitude of the degree of change adjustable on the resistor 61 by the output voltage of the counterclocking step 21 and, if so, by the setting of the resistor 55. That is, the value by which the temp 148 must be changed to pass through the dead zone of 1 volts and switched from heating to cooling or from cooling to heating is easily adjustable by the resistor 61 and / or the resistor 55, if any.

Claims (5)

148218 1. A regulator for an air conditioner, at which the room temperature is controlled by heating or cooling the air, with a room temperature measuring bridge, an overlay link influenced by the differential signal and a temperature controller with a common input for a continuous heat and continuous cooling setting area , wherein the input of the temperature controller is derived from the output of the overlay link, characterized in that the temperature controller (17) 10 contains in a known manner a continuous heat setting means (29) and a continuous cooling setting means between whose setting areas there is a dead zone (V). the input signal (V ·) of the temperature regulator (17) derived from the output signal of the superconductor (9) is applied to an overlay link (9) influencing the decoupling step (21), the output of which changes its input signal at a temperature zone within the dead zone of the temperature controller. (Vj) changes from a lower limit value to a higher limit value and whose 20 influence on the overlay link output can be set. Control device according to claim 1, characterized in that the counter-coupling step (21) has a very large amplifier differential amplifier (A2) whose output over a counter-coupling resistor (63) with parallel coupled reverse diode (67) is connected to its inverting input (-) and across a voltage divider resistor (61) with its non-inverting input (+) and the one, which bears on a reference potential (23), that the input signal (Vi) of the temperature controller (17) is applied to the inverting of the differential amplifier (A2) input (-) over an input resistor (65) whose resistance value (Rgs) is less than the resistive value (Rg3) of the interconnection resistor (63) and the output signal of the decoupling step (21) is subtracted from an adjustable output of the voltage divider resistor (61). Control device according to one of claims 1-2, characterized in that the overlay link (9) has a high gain differential amplifier (Al) coupled to a resistor (57) with a first, its inverting input (-) with the one bridge output (23) connecting input resistor (53) and with another, its inverting input (-) with the output (25) of the counter-coupling step (21) connecting input resistor (55), and the non-inverting input (+) of this differential amplifier (A1) is connected to the second output (7) 15 of the bridge (5). Control device according to one of Claims 1 to 3, characterized in that the cooling and heating setting means (33, 29) are each coupled to a countercoupled differential amplifier (A4, A5) with high amplification, if non-inverting inputs ( +) both are applied to the input signal (Vi) derived from the output signal (9) of the overlay link (9), and whose inverting inputs (-) each over an input resistor (87, 93) are connected to an upper and a lower outlet of a voltage divider ( 97, 99, 101) and that the voltage divider's outlets and the equipment ranges of these differential amplifiers (A4, A5) are selected such that the equipment area of one adjusting member (27) lies in the equipment region of one differential amplifier (A5) and the equipment region 30 of the other adjusting means (33) is located in the output region of the second differential amplifier (A4). Control device according to any one of claims 1-4, characterized in that between